August 1998 Gasification Archive

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From english at adan.kingston.net Mon Aug 3 22:35:49 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney Flue Optimisaion
In-Reply-To: <v01520d02b1e76129f602@[199.2.222.130]>
Message-ID: <199808040245.WAA17877@adan.kingston.net>

Deer Elk, and other undulates( I couldn't resist)
Hi Kevin,
It's great to have another activist on the list.
I hope you guys aren't making all the progress 'off list'.

> Dear Elk
> You indeed have a fascinating project!!

I agree. I am especially fascinated by the vagaries of chimney draft
in this and other applications. So I would like to add some draft of
my own.

> You ask how to optomise flue velocity....may I suggest that this
> is the wrong question: What you need is the stack diameter and
> stack system design which will optimise the static pressure developed
> at the base of your carbonizing chamber, just below the grates. It
> is the static pressure developed below the grates that draws air down
> through the sawdust bed.

> The first step is to install a static pressure gage which reads the
> negative static pressure developed below your grates.. This will give
> you insights on how to operate your present system in a manner to get
> maximum static pressure development.
>
> This can be done with a piece of 1/2" steel tubing or pipe, inserted
> into the chamber below the grate and sealed with an appropriate
> packing. Clay packed in place with appropriate support is quite
> adequate. Run this pipe up vertically about 5 ' above ground level,
> and then add a piece of clear plastic tubing, formed into a "U"
> shape. Add water to the tube. Read the difference in water height in
> each leg, as the static pressure developed. I would guess you would
> develop in the range of 1" static pressure development.

I think you may be optimistic by a factor of 5, give or take. Check
out the table at http://www.ikweb.com/enuff/public_html/Chimdr.jpg

To measure variations of less than 0.1"WC will require at least, some
form of inclined manometer made of clear plastic tubing, at best
something much more expensive.

Another issue is the static pressure loss from the air intake of the
firebox at the base of the chimney. The movement of the additional
air, required for complete combustion, into the firebox comes at the
expense of at least some of the chimney's total draft.
>
> This will be a powerful tool, to aid you in determining the
> importance of the many variables associated with the operation of
> your system.
>
> 1: You can determine the optimum positioning of the firebox cover,
> which lets air into the stack for ignition and on-going combustion of
> flare gas.
>
> 2: You can check for leakage in the system, once you have a general
> procedure and empirical data developed.
>
> 3: You can develop optimal standards for the rate of charging of new
> sawdust
>
> 4: You can determine the maximum desirable height of charcoal in your
> system, before you stop charging fresh sawdust. (For example, once
> the system is up to temperature, I would guess that you will find
> that you get excellent carbonization rates until you reach a height
> of say 2', and thereafter, the gas flow rates drop significantly
> because of flow resistance through the deeper bed. Expressed in
> different terms, you may very well be able to get 300 kG/day out of a
> given system, if you charge to only 2' height, but if you charge to
> 3' height, your daily production drops to only 150 kG/Day
>
> The key thing, I would guess, is operation of the inlet air control
> at teh base of the stack, for combustion of flare gases. Too much
> air, and you have excessive pressure loss because of greater gas
> flow, and you lower the temperature of teh products of combustion,
> which reduces the draft developed. Too little air, and you don't
> combust all the flare gas, and don't develop maximum stack
> temperature. Basically, restrict the air supply progressively, until
> smoke is visible at the stack outlet, then open it progressively,
> until the smoke is almost gone. Watch the Manometer, to determine
> conditions yielding maximum pressure differential.
>
> This then tells you how to operate your air inlets to get maximum
> stack temperature.
>
> Then, with flare gas combustion conditions optimal, you experiment
> with other conditions. My initial guess is that you should try to
> maintain maximum suction under the grate, and that when your bed
> height is too high, you will probably see a drop in the draft,
> because the reduced gas flow results in lowering stack temperatures,
> and consequently, lower draft.

The theory certainly suggests that lower temperatures reduce draft.
However my interpretation of Jay Shelton's book on Solid Fuels is
that in practice, with chimney diameters in this range 20cm +/-,
average flue gas temperatures over 600F(333C) actually slightly reduce
the chimney capacity, due the higher friction losses associated with
the higher velocities of the hotter, less dense, flue gasses. A drop
to 400F and you loose a few percent also.

>
> Optimal design of the stack is not simple. You need to know the
> approximate stack gas composition, its flow rate, and temperature.
> The two resulting dimensions are stack diameter and stack height.
> Sometimes there are external considerations, which change things
> markedly. Perhaps the optimal stack was 1' diameter, and 40' tall,
> but you have cheap access to a 2' diameter culvert, 20' long. Perhaps
> there are height restriction constraints.. A good starting point
> would be a velocity of about 300 feet per minute.

Lets consider a minimum instead of an optimum.
I figure that Elsen's goal of around 30kg/hr of sawdust converting
to 7kg/hr of charcoal would yield a producer gas combustion rate that
would require a safe minimum chimney diameter of 20cm when 6 m tall.
A larger size might let you speed up the process. My hunch is that
between 18cm and 30cm dia. there lies an optimum that will not be
worth pursuing. It would result in only a slight improvement. Pick a
size in that range that is available. What ever is cheapest. After
all Elsen, your experience will soon be worth more than my words, and
next month, you'll be wanting a bigger system.

> Stacks should, in theory, be insulated to maximize average stack
> temperature. However, you have to be very careful here.... if you
> insulate at the base, the stack gets too hot, and the steel
> scales. Scaling gets bad above about 800 degrees F. If the steel
> stack does not glow in the dark, then you are below 800 F. Ideally,
> what you should have is insulation on the inside of the stack, up far
> enough to prevent scaling temperatures, and then insulation on the
> outside, to reduce heat loss from there on, to maximize average stack
> temperature.
>
> Hopes this helps you get a bit further with your operation. Once you
> get some of the above implemented, perhaps there are some other
> things that can be done for increase performance even further.
>
> Please keep me posted on your results.
>
> Kevin Chisholm

I would certainly agree with Kevin, that having some way to measure
the draft at various points in the system would be ideal for
developing an understanding of the system, and what various changes
actually mean.

Alex
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Webpage

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From kchishol at fox.nstn.ca Tue Aug 4 02:36:32 1998
From: kchishol at fox.nstn.ca (kchishol)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney Flue Optimisaion
In-Reply-To: <v01520d02b1e76129f602@[199.2.222.130]>
Message-ID: <35C6AD69.E1738379@fox.nstn.ca>

*.English wrote:

> Deer Elk, and other undulates( I couldn't resist)
> Hi Kevin,
> It's great to have another activist on the list.
> I hope you guys aren't making all the progress 'off list'.

Not at all!!! I am sure we all want helpful information disseminated.
...del...

> > The first step is to install a static pressure gage which reads the
> > negative static pressure developed below your grates.. This will give
> > you insights on how to operate your present system in a manner to get
> > maximum static pressure development.
> >
> > This can be done with a piece of 1/2" steel tubing or pipe, inserted
> > into the chamber below the grate and sealed with an appropriate
> > packing. Clay packed in place with appropriate support is quite
> > adequate. Run this pipe up vertically about 5 ' above ground level,
> > and then add a piece of clear plastic tubing, formed into a "U"
> > shape. Add water to the tube. Read the difference in water height in
> > each leg, as the static pressure developed. I would guess you would
> > develop in the range of 1" static pressure development.
>
> I think you may be optimistic by a factor of 5, give or take. Check
> out the table at http://www.ikweb.com/enuff/public_html/Chimdr.jpg

I stand corrected, and apologize for the error; for one thing, I misread
the stack height as 15 meters, rather than 5 meters ~15'. Your ungulate
designation was indeed appropriate: I feel sheepish!! :-)

The 1/2" steel entry pipe is necessary, to avoid plugging by condensible
tars, and to provide heat loss, so that the plastic or rubber tubing is not
burned.

> To measure variations of less than 0.1"WC will require at least, some
> form of inclined manometer made of clear plastic tubing, at best
> something much more expensive.

This is easily done with a simple glass tube, on a 1:10 slope, partially
filled colored water; cooking oil would be better, to dampen fluctuations.
If you don't know the density of the oil, you still get a good relative
reading. To get an absolute reading, you simply correct for oil density.

> Another issue is the static pressure loss from the air intake of the
> firebox at the base of the chimney. The movement of the additional
> air, required for complete combustion, into the firebox comes at the
> expense of at least some of the chimney's total draft.

Good point!!
....del...

> The theory certainly suggests that lower temperatures reduce draft.
> However my interpretation of Jay Shelton's book on Solid Fuels is
> that in practice, with chimney diameters in this range 20cm +/-,
> average flue gas temperatures over 600F(333C) actually slightly reduce
> the chimney capacity, due the higher friction losses associated with
> the higher velocities of the hotter, less dense, flue gasses. A drop
> to 400F and you loose a few percent also.

I'll have to check this one. As I recall, the lower viscosity of the heated
products of combustion basically offsets what would otherwise be greater
flow losses because of increased volume at higher temperatures.

> >
> > Optimal design of the stack is not simple. You need to know the
> > approximate stack gas composition, its flow rate, and temperature.
> > The two resulting dimensions are stack diameter and stack height.
> > Sometimes there are external considerations, which change things
> > markedly. Perhaps the optimal stack was 1' diameter, and 40' tall,
> > but you have cheap access to a 2' diameter culvert, 20' long. Perhaps
> > there are height restriction constraints.. A good starting point
> > would be a velocity of about 300 feet per minute.
>
> Lets consider a minimum instead of an optimum.
> I figure that Elsen's goal of around 30kg/hr of sawdust converting
> to 7kg/hr of charcoal would yield a producer gas combustion rate that
> would require a safe minimum chimney diameter of 20cm when 6 m tall.
> A larger size might let you speed up the process. My hunch is that
> between 18cm and 30cm dia. there lies an optimum that will not be
> worth pursuing. It would result in only a slight improvement. Pick a
> size in that range that is available. What ever is cheapest. After
> all Elsen, your experience will soon be worth more than my words, and
> next month, you'll be wanting a bigger system.

I feel you are right in the right ballpark. I would guess 6" stovepipe
would be about it. However, a bigger diameter and a bigger height would
allow you to run at a lower temperture to get the same draft, but with a
longer chimney life. If Elk has access to fire clay, he could line the
inside of a 8" or 10" sheet metal chimney with 1" or 2" of clay, to build
an insulation effect, permitting higher temperatures with longer life. Heat
slowly the first time, until the clay dries, to avoid spalling. Then make a
very hot "first fire" to "fire" the clay into brick.

...del...

I would certainly agree with Kevin, that having some way to measure

> the draft at various points in the system would be ideal for
> developing an understanding of the system, and what various changes
> actually mean.

Looks like we are in violent agreement!! :-)

Elk, I hope you keep us all posted with your results!!

Kevin Chisholm

From REEDTB at compuserve.com Tue Aug 4 07:20:09 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:36:01 2004
Subject: Not goodbye, Doug Williams, I hope
Message-ID: <199808040729_MC2-5517-BB1@compuserve.com>

Dear Doug:

I am so sorry to hear that Fluidyne Gasification is closing shop. It must
be a great personal disappointment to you and will be a loss to your
country and the world.

I hope that you will continue to be a member of the gasification community
here at CREST and that you will continue to offer advice from your vast
storehouse of experience. (What is Humphries doing now?)

Personally I have been working on gasification since 1974, but it was my
prime source of income only from 1980-86 when we built the SERI/NREL oxygen
gasifier. My deceased friend Harry LaFontaine said that no one ever made
money selling gasifiers, but they have made lots of money doing projects in
gasification. Still too true.

I believe gasification is one of the last holdouts of the physical world
against science. We understand the atom and DNA, but there are still many
things to learn about pyrolysis and gasification. It is an endlessly
fascinating field, mixing science, engineering and invention, so I guess
I'll hang in here until I'm hung out.

We are working on tar free gas generation and gasifiers for agricultural
residues. I am investigating new areas of pyrolysis and the full spectrum
of downdraft gasification.

Yours truly, TOM
REED
CREST,
GASIFICATION
~~~~~

Tom, Dick and Harry et al . . .

When I read your contributions this morning the motivation to comment
became stronger than my desire to plod down the farm and prune my poor
neglected Lime orchard.

Since 1976 I have personally been involved with a research development
manufacture and market development of gasifiers for engine powered
electricity production. Along the way I have accumulated "a little bit of
knowledge" spoken to Presidents and Prime Ministers, Ministers of Energy,
key Ministers of State and possibly a few hundred thousand really committed
people pledging support for renewable energies and biomass in particular.
I have lost count of how many times I have picked up touring academics from
the airport and spent days assisting them with their studies and surveys.

We have attended numerous conferences, mounted working displays at trade
exhibitions, been listed on untold numbers of renewable directories,
responded to consultants "latest" government resource papers etc. In fact
its hard not to believe our company hasn't financed the whole pseudo
activity that has developed around the technology we have endeavoured to
implement.

In order to keep the checks and balances in order mentally I can walk under
mill timber, cut firewood and enjoy the protection of eucalyptus and pine
plantations planted by ourselves. We are also custodians of a small block
of native bush with trees and plants you can find fossils of dating back 80
million years. Indeed biomass can be sustainable but unfortunately people
and money are not.

We closed our workshop dedicated to biomass gasification at the end of June
and Fluidyne becomes just an office full of files of other peoples
unfulfilled dreams. Unfortunately the cost of providing answers to these
dreams has to come from somewhere and Fluidyne has always financed its own
activities not having access to the public purse. You might suggest we
should have developed the gasification processes for RDF and other abundant
biomass wastes which others so flippantly discuss on this network.
Fluidyne has always had parallel R and D for these fuels with one critical
requirement in mind, that of a tar free gas. It is possible and you can
quote me with making that statement. Having said that no doubt the well
informed will add me to the list of purveyors of snake oil when I ask you
to put up your money to make it happen!

Our closure is no admission on my part that we failed to meet our
objectives on our part as a manufacturer, or that our market assessments
were incorrect. The rural world is still without electricity and the cost
of fossil fuel or distance to transport it will continue to be an inhibitor
for power generation in those places. Like everything it is 'horses for
courses' but there are exceptions for every rule in the book - except your
bank book.

So my friends if dedication, enthusiasm, environmental concerns, knowledge,
market surveys, international market opportunities are part of your
vocabulary . . . make sure you pay for these ideals from your own pocket.
It is a good measure for yourself to evaluate if you have it right, and
protection for others if you have not. None of us have the right to
ridicule the aspirations of others, but we do have a responsibility to
identify the snake oil when our experiences tell us that it should exist.

Signing off . . . still dedicated, but for my own good . . .

DOUG WILLIAMS
Fluidyne Gasification (now closed)

<
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From REEDTB at compuserve.com Tue Aug 4 19:26:34 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney Flue Optimisaion, Dwyer guage
Message-ID: <199808041935_MC2-5529-F3EE@compuserve.com>

Dear Stove optimizers:

Great discussion on the importance of draft and one way to measure it.

The Dwyer Company makes a "draft guage" for about $30 that beats a plastic
U tube all hollow. I have one in my lab and use it all the time. It is
effectively a sealed tube with red oil calibrated for inches of water. The
lower half of the tube is on a slope, so that it can resolve as little at
0.01 inches of water; the upper part rises steeply to the closed end and
can measure 30 inches of water max. So it is pseudologarithmic in action.

Go for it, Alex............. TOM REED
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From elk at arcc.or.ke Wed Aug 5 12:08:05 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:36:01 2004
Subject: sawdust carbonisation
Message-ID: <199808051617.TAA26903@arcc.or.ke>

I'm still at it.

Currently building a 6 m tall by 15 cm dia. stack for the larger kiln.

All going according to plan, I should see a three-fold increase in the rate
of carbonisation per m2 of sadust surface area within the kiln......

Thats interpolative gut-feel top-of-the head non-scientific guesswork. Lets
see how close I come.

The kiln should be ready in under a week. I'm making the chimney out of
scrap steel salvaged from 44 gal oil drums to keep costs down and local
applicability up.

Thanks for the advice on chimney dynamics!

elk
----------------------------------------------------------------------------
-----------------------------------------
Elsen L. Karstad P.O. Box 24371 Nairobi Kenya. Fax (+254 2) 884437 Tel
884436, 882375
----------------------------------------------------------------------------
-----------------------------------------

From elk at arcc.or.ke Wed Aug 5 12:22:16 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:36:01 2004
Subject: easy lite kilns
Message-ID: <199808051631.TAA27247@arcc.or.ke>

I've just rec'd a requets for the address of easy-lite kilns (a Montreal
based Co.) from somebody in Chile.

If anyone has this at hand, could they please reply to:

ghp-sk@entelchile.net

Many thanks;

From REEDTB at compuserve.com Mon Aug 10 17:42:44 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:36:01 2004
Subject: GAS-L: Not goodbye, Doug Williams, I hope
Message-ID: <199808101752_MC2-55B4-89F8@compuserve.com>

Dear Doug:

We would love to see your best gasifier system photos on the WED from
Graeme and we can copy them elsewhere if they threaten to disappear.

While you were dismantling your workshop I spent a solid week readying my
lab for future projects, throwing out 8 years of accumulated stuff, and
making the survivors much more useful since I will be able to find them!

Leg Health you say? Believing that the legs are a solid foundation for a
long life, I play racketball and tennis several times a week. I
occasionally get leg cramps and the other night I got LEGS cramps - both at
once, more excruciating than I have ever had. I looked on the WWW for
wisdom on leg cramps and only found quinine dubiously recommended. Any
wisdom?

Your netpal, TOM REED
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From REEDTB at compuserve.com Mon Aug 10 17:42:46 1998
From: REEDTB at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:36:01 2004
Subject: 'Draft Gauge' from Dwyer Company General Info
Message-ID: <199808101752_MC2-55B4-89F2@compuserve.com>

Dear Huynh:

The Dwyer Instrument Co. is located at Box 373, Michigan City, IN 46361;
phone 219 879 8000.

I found the low pressure gauge on p. 856 of the Grainger catalogue, $20.96.

I am enclosing a list of our books on gasificaiton. That's all I know ....
: )

TOM REED

Message text written by "Huynh, Danh"
>Dear Tom,

I have just got an email message passed to me from a colleague (Tony
Campisi
who is on the mailing list of BioGasification Group) regarding the above
pressure drop measurement. It sounds interesting. I would appreciate if
you could pass on to me a contact address of Dwyer Company so that I may
decide to purchase one.

Also, if you have any interesting information/development on gasification
of
biomass, coal, etc. I would like to know and learn. I do not know much
about SERI/NREL oxygen gasifier as mentioned in your note to Doug Williams.
Can it be used with air ? and would greatly appreciate to receive some
info.
We have been working on mainly on fluidised-bed
gasification of low-rank coal for some years.

My email address is: huynd@hrl.com.au

Regards,

Danh
<

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From LannyH at aol.com Tue Aug 11 19:57:07 1998
From: LannyH at aol.com (LannyH@aol.com)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney design (minimizing the vena contracta)
Message-ID: <1e24ad93.35d0dc35@aol.com>

I was able to reduce the chimney size on a cooker that I am designing and
prototyping by minimize the vena contracta effect. With a plain duct opening
an energy loss occurs in the conversion of static pressure to velocity
pressure. There is an uncontrolled slow down of the air in a vena contracta to
the downstream velocity that results in a loss.
To minimize this loss use a transition piece at the base of the chimney where
it attaches to the unit to help get the gasses all going in the right
direction. The optimum size duct transition (also called a reducer or in this
case an increaser) is 3 diameters high and aprox 3 dia. wide at the base (or
22.5 deg slope shoulders). A 4-inch stack would need a transition 12-inch
high and 12-inch diameter at the base.
I welded a female collar to my transition so I can just slide a stack pipe in
or out. I am testing with conductor pipe also known as gutter down spout. It
is cheep and easy to work with.
Lanny
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
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For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From english at adan.kingston.net Wed Aug 12 23:14:51 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney design (minimizing the vena contracta)
In-Reply-To: <1e24ad93.35d0dc35@aol.com>
Message-ID: <199808130324.XAA00508@adan.kingston.net>

Dear Lanny, Kevin and stovers all,
Glad to hear of your work Lanny. Could you share any more numbers
with us? Are you measuring static pressure and/or velocity?
Have you thought about reducing the enlargement or exit losses at the
top of the chimney? I suppose that the chimney would start to look
like a miniature, slender version of a power plant cooling tower.

> I was able to reduce the chimney size on a cooker that I am designing and
> prototyping by minimize the vena contracta effect.

Can you give us the dimensions, before, and after?

> With a plain duct opening
> an energy loss occurs in the conversion of static pressure to velocity
> pressure. There is an uncontrolled slow down of the air in a vena contracta to
> the downstream velocity that results in a loss.
> To minimize this loss use a transition piece at the base of the chimney where
> it attaches to the unit to help get the gasses all going in the right
> direction. The optimum size duct transition (also called a reducer or in this
> case an increaser) is 3 diameters high and aprox 3 dia. wide at the base (or
> 22.5 deg slope shoulders). A 4-inch stack would need a transition 12-inch
> high and 12-inch diameter at the base.

I don't know what your prototype is designed to do, but in terms of
developing a wood fuelled cooking stove with lower emissions, a short
chimney can add some much needed static pressure to the system.

The recent discussions, in response to Elsen Karstad's chimney
requirements, have caused me to have a second look at some of my
reference books. I pulled them out to show Ronal Larson during his
recent visit. Unfortunately there wasn't enough time to explore the
formulas then, although I treasure the image of Ronal, following me
around while I fed some sheep, all the time trying to read the
section on chimneys in the rather large: Steam, Its Generation
and Use. Since then I have been plugging numbers into some of the
formula it contains. I need some help establishing a reasonable
friction factor for small chimneys, as opposed to power plant stacks.
I have found no evidence to support the statement that I found in
another reference, that chimneys have a peak capacity at an average
temperature of around 600F. It wouldn't be the first time for me
that the formulas failed to follow the facts.

Yours, in-Venting, Alex

> I welded a female collar to my transition so I can just slide a stack pipe in
> or out. I am testing with conductor pipe also known as gutter down spout. It
> is cheep and easy to work with.
> Lanny
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Webpage

From mheat at mha-net.org Thu Aug 13 05:47:09 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney design (minimizing the vena contracta)
In-Reply-To: <1e24ad93.35d0dc35@aol.com>
Message-ID: <199808130956.FAA15947@tor-smtp2.netcom.ca>

Hello Alex and other stovers:

Canada Mortgage and Housing Corp (CMHC) did a lot of work modelling
residential chimneys in the 1980's. The Canadian Housing Information Centre
http://www.cmhc-schl.gc.ca/cgi-cmhc/enfrmsite.pl?target=/PAC/Press/96-10-02.
html

Should be able to provide a list of research reports that were published on
venting. Two of the most interesting efforts were FLUESIM and WOODSIM,
computer models that include things like house envelope leakage, wind
effects, chimney materials, chimney cross section and height, etc. FLUESIM
can simulate gas and oil furnaces, and WOODSIM can simulate wooedburning
fireplaces and stoves. We have them available on our website at:
http://mha-net.org/html/software.htm

Best.............Norbert Senf

At 11:22 PM 12/08/98 -0500, you wrote:
>Dear Lanny, Kevin and stovers all,
>Glad to hear of your work Lanny. Could you share any more numbers
>with us? Are you measuring static pressure and/or velocity?
>Have you thought about reducing the enlargement or exit losses at the
>top of the chimney? I suppose that the chimney would start to look
>like a miniature, slender version of a power plant cooling tower.
>
>> I was able to reduce the chimney size on a cooker that I am designing and
>> prototyping by minimize the vena contracta effect.
>
>Can you give us the dimensions, before, and after?
>
>> With a plain duct opening
>> an energy loss occurs in the conversion of static pressure to velocity
>> pressure. There is an uncontrolled slow down of the air in a vena
contracta to
>> the downstream velocity that results in a loss.
>> To minimize this loss use a transition piece at the base of the chimney
where
>> it attaches to the unit to help get the gasses all going in the right
>> direction. The optimum size duct transition (also called a reducer or in
this
>> case an increaser) is 3 diameters high and aprox 3 dia. wide at the base
(or
>> 22.5 deg slope shoulders). A 4-inch stack would need a transition 12-inch
>> high and 12-inch diameter at the base.
>
>
>I don't know what your prototype is designed to do, but in terms of
>developing a wood fuelled cooking stove with lower emissions, a short
>chimney can add some much needed static pressure to the system.
>
>The recent discussions, in response to Elsen Karstad's chimney
>requirements, have caused me to have a second look at some of my
>reference books. I pulled them out to show Ronal Larson during his
>recent visit. Unfortunately there wasn't enough time to explore the
>formulas then, although I treasure the image of Ronal, following me
>around while I fed some sheep, all the time trying to read the
>section on chimneys in the rather large: Steam, Its Generation
>and Use. Since then I have been plugging numbers into some of the
>formula it contains. I need some help establishing a reasonable
>friction factor for small chimneys, as opposed to power plant stacks.
>I have found no evidence to support the statement that I found in
>another reference, that chimneys have a peak capacity at an average
>temperature of around 600F. It wouldn't be the first time for me
>that the formulas failed to follow the facts.
>
>Yours, in-Venting, Alex
>
>
>> I welded a female collar to my transition so I can just slide a stack
pipe in
>> or out. I am testing with conductor pipe also known as gutter down
spout. It
>> is cheep and easy to work with.
>> Lanny
>> Stoves List SPONSORS and ARCHIVES:
>> http://solstice.crest.org/renewables/stoves-list-archive/
>> Stoves Webpage
>> http://www.ikweb.com/enuff/public_html/Stoves.html
>> For information about CHAMBERS STOVES
>> http://www.ikweb.com/enuff/public_html/Chamber.htm
>>
>>
>Alex English
>RR 2 Odessa Ontario
>Canada K0H 2H0
>Tel 1-613-386-1927
>Fax 1-613-386-1211
>Stoves Webpage
>
>Stoves List SPONSORS and ARCHIVES:
>http://solstice.crest.org/renewables/stoves-list-archive/

>Stoves Webpage
>http://www.ikweb.com/enuff/public_html/Stoves.html
>For information about CHAMBERS STOVES
>http://www.ikweb.com/enuff/public_html/Chamber.htm
>
----------------------------------------
Norbert Senf---------- mheat@mha-net.org
Masonry Stove Builders
RR 5, Shawville------- www.mha-net.org/msb
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092

From english at adan.kingston.net Thu Aug 13 18:01:55 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:01 2004
Subject: (Fwd) BOUNCE stoves@crest.org: Non-member submission from [
Message-ID: <199808132211.SAA04164@adan.kingston.net>

Dear Jonathan,
I took the liberty of subscribing you to the list, and forwarding
this message. A few comments of my own are added below.

From: JOnathan Otto, Village Energy Solutions

As I am new to the Stoves list, this will serve as a brief introduction
and initial request for assistance. I am part of a group of African,
European and North American development workers (engineers, project
managers, agroforesters, extensionists, etc.) working on domestic energy
issues for low- wealth users. Our current focus: use of plant oils
(initially oil of Jatropha curcas) in low-tech cooking devises, with
secondary interests in fertilizer (seed cake), lighting (we've developed
and are now testing a very cheap and apparently effective
Jatropha-fueled lamp), and other ancillary applications of oil-rich
plants and their products. Aspects of our overall approach that may
interst Stove list readers in general: we are an integrated group --
with direct connections from research to field testing and
dissemination, and we are 'technologically neutral', i.e., ready to work
on and promote whatever biomass (or solar!) technologies work best in a
given situation.

The immediate question: what is the state-of-the art in low-cost stoves
fueled by Jatropha or other plant oils? Who is working on this issue
and how can we collaborate?

Alex writes :
Although I can't answer your question, I hope that other list members
will. I would like to point out that I can post pictures, drawings
and such, on a web page (check "stoves webpage" URL at the bottom of
this message) to facilitate communications on this list.

I like the phrase 'technologically neutral'. That sounds a bit like
'solution oriented'.

Alex English
PS. I think I have heard of your work from a fellow Vermonter. Are
you also involved with chip fired boilers?

From greensue at hotmail.com Thu Aug 13 22:53:38 1998
From: greensue at hotmail.com (Susanne Machler)
Date: Tue Aug 31 21:36:01 2004
Subject: ACTIVATED Charcoal
Message-ID: <19980814030311.15141.qmail@hotmail.com>

Hi there stovers.

I am a silent listener on your group and operate a 7 acre renewable
homestead in the Caribbean. I am presently having problems keeping up
with the prices of things imported from the States. One such item that I
need often but have raw materials for in abundance is the activated
carbon filters made from coconut shells.

Can you charcoal and stovers help me to set up a rig to make my own
activated charcoal?? I need it especially in my self made high volume
water distiller, as well as hydroponics setup in the purifying water
that we treat ourselves.

I would be foever indebted.

Sue Maechler.

______________________________________________________
Get Your Private, Free Email at http://www.hotmail.com
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For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From larcon at sni.net Fri Aug 14 01:50:34 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:01 2004
Subject: australian outback coffee maker
Message-ID: <v01540b09b1f969edae46@[204.133.28.8]>

Stovers:

The following came in on July 30 - shortly after I started my vacation
which ended today. Anyone able to help Tim? Ron

>Hello,
>
>I am trying to source this out. A friend of mine was down there and
>they had this cone shaped coffee maker. One would grab some small
>sticks, put them under it, light it and within a minute or so, coffee.
>Do you know of this or where else I might go to track this item down.
>
>Thanks ahead for any direction.
>
>Tim Janosik

janosik@spectrumevents.com

From english at adan.kingston.net Fri Aug 14 07:27:39 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:01 2004
Subject: E-Z-est WAY 831G ?
Message-ID: <199808141137.HAA13726@adan.kingston.net>

A non list member sent the following message.Alex

From: theresa <theresag@mail.quik.com>

where can I find information on a stove named E-Z-est WAY 831G ?
I cna't seem to find anything on the web. Wondered if you could help?
Thanks,

From elk at arcc.or.ke Fri Aug 14 08:19:03 1998
From: elk at arcc.or.ke (E. L. Karstad)
Date: Tue Aug 31 21:36:01 2004
Subject: Australian Outback Coffee Maker
Message-ID: <v01520d01b1f9f282faa6@[199.2.222.134]>

In response to Tim Janosik's query about an Australian Outback Coffee Maker;

I used one of these daily during a brief 2 year stint of camping in the
Masai Mara here in Kenya.

A verbal desciption should suffice, as it's pretty simple.

Externally it's a cylinder approx 30 cm high by 17 cm in diameter. A spout
runs at a slight angle off to one side- connected all the way from the base
to the top (though variations are possible I'm sure). This spout should
connect through the wall of the cylinder at at least two points- the very
bottom, for efficient pouring, and the very top, for steam venting and
pressure release during filling. On the opposite side of the spout is a
handle- designed with consideration for heat transfer and balance.

Internally, an open ended cone runs from the very bottom of the cylinder
where it is at it's largest- the inside diameter of the cylinder- and
tapers to about 5 cm diameter at the top where it exits centrally from the
top of the (otherwise sealed) cylinder. To further clarify this- the bottom
of the cylinder is open. That's where the fire is. The top of the cylinder
is sealed except for the 5 cm. diam. hole which is the top opening of the
internal cone- the chimney.

Now, to add the water, you can either pour it down the spout or have a hole
through the top cap of the cylinder between the handle and the chilmney
hole- on the opposite side of the spout. Mine had this, with a small
permanent funnel attached.

The bottom of the kettle can have a ring extension of about 5 cm with about
6 holes cut through of about 2 cm diameter. This allows the kettle to be
set on bare dirt and still 'breathe', as well as providing a solid base.

The kettle is efficient due to a high contact are between the inner cone
where the fire is set, and the water within the space between cone and
cylinder. When full, the kettle is somewhat top-heavy, as most of the water
is in the upper half. I can't tell you off-hand how much water it carries-
a bit less than half of the simple cylinder's volume.

I used sticks and twigs and cheated- fired it up every morning with a small
dollop of kerosene. I didn't boil up my coffee in it- it's not possible to
clean well inside- but used the boiling water and a filter drip straight
into my mug. I'd say it was at least as fast to the boil as a regular
electric kettle. That's not bad by bush standards!

Let me know if you make one.

regards;

elk

_____________________________
Elsen Karstad
P.O Box 24371 Nairobi, Kenya
Tel/Fax:254 2 884437
E-mail: elk@arcc.or.ke
_____________________________

From LannyH at aol.com Fri Aug 14 09:07:17 1998
From: LannyH at aol.com (LannyH@aol.com)
Date: Tue Aug 31 21:36:01 2004
Subject: Introduction
Message-ID: <1f9bb1f4.35d438b2@aol.com>

Hello all,
My name is Lanny Henson
I am in NW Georgia
My use of computers, mail list ,e-mail, the Internet and my writing skills are
limited. I apologize in advance.
I am a sheet metal contractor and fabricator, 25 years experience, some
college. I have a well-equipped shop but no computerized plasma table, can
shear 10 ga and form 16-14 ga
I do mostly industrial ventilation work, commercial kitchen exhaust systems
and specialty fabrications.
As a hobby I am designing and prototyping a BBQ cooker that is energy
efficient and thanks to this list will be clean burning. I started,
prototyping fireboxes in Nov 97, then began working on the cooking chamber
soon after. I call my current prototype #6. One of the unique features of my
design is a self-feeding firebox that will burn wood and or charcoal. My
current prototype has a 35 cu. Ft. cooking chamber. It takes about 1 pound of
charcoal per hour to hold 225 deg. F. I want my next prototype to also
function as an oven that could be used as survival cooker or maybe a community
oven for a small village.
The discussed of gas flaring and secondary combustion on this list has struck
my interest. I may be willing to prototype some of your devices. I am doing
some secondary combustion experiments this weekend.
In my next note I will tell you about my charcoal making experiences, and
describe my cooker, and talk about my source. " Industrial Ventilation" for
the vena contracta losses that I talked about in my earlier note
> Alex said, "I need some help establishing a reasonable friction factor for
small chimneys, as opposed to power plant stacks"
"Industrial Ventilation" also has a friction loss chart for small round duct.
I am very pleased to find to find this list.
Lanny
Stoves List SPONSORS and ARCHIVES:
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From larcon at sni.net Sat Aug 15 09:18:06 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:01 2004
Subject: Cynthia Knowles responding to Jonathon Otto on Jatropha
Message-ID: <v01540b00b1fa91066457@[204.133.28.47]>

Stovers: Today, (presently) non-list-member Cynthia Knowles passed this
information on to Jonahton Otto's message of yesterday in a bounced
message:

>
>Dear Jonathon,
>
>I posted your letter to the bioenergy list because they may have some
>suggestions regarding biofuels also. Although I do not have information on
>cooking stoves fueled by Jatropha oil, we would like to learn more about
>those oils/fuels derived crops that may be appropriate for pressurized
>stoves in developing countries. Are you working with wick stoves? We have
>just completed a cooking needs and stove and fuel use assessment in the
>Dominican Republic to determine the feasibility of alternatives to fuelwood.
>We are currently looking into liquid kerosene but have not entered into a
>pilot stage as of yet. We believe that those who are able to make the
>switch to a liquid fuel may one day also make a smooth transition to a
>liquid biofuel, provided that fuel costs are competitive and equipment
>investment within their means.
>
>Do you know of ANY low-cost stoves currently powered by a liquid biofuel?
>Looking forward to hearing more about your work,
> Cynthia L. Knowles
> Enersol Associates, Inc.
> A Member of
> The Global Transition Group
> 55 Middlesex Street, Suite 221
> North Chelmsford, MA 01863 USA
> Tel: (978)251-1828/29; Fax: (978)251-5291
> E-mail: cknowles@igc.apc.org

From larcon at sni.net Sat Aug 15 23:18:35 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:01 2004
Subject: Tim Janosik request on small coffee heater
Message-ID: <v01540b04b1fa97c5fa03@[204.133.28.47]>

Tim and Stovers:

1. Thanks to Peter Verhaart and Elsen Karstad for their responses
to Tim. I also received a reminder from list reader Andrew Heggie of his
reporting more than a year ago about a similar UK product called the
"Kelly Kettle". Andrew says it and price can be seen at:

http://www.hawkin.co.uk/curio.htm

2. The concept of an interior fuel chamber and chimney is inherent
in the Russian Samovar that has been mentioned several times on this list.
I would appreciate hearing from Dr. Yury or others of any studies of the
efficiency of the samovar. I would guess that Samovars may have been used
for centuries - and that their efficiency may be very high.

3. Can anyone can tell me how the bottom of a samovar (or the
Kelly Kettle or the Australian heater or any unit with an inner
combustion/pyrolysis zone and an outer water jacket) is sealed? Can this
sealing be done by traditional metal workers in remote villages?

Regards Ron

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From dstill at epud.org Sun Aug 16 01:05:52 1998
From: dstill at epud.org (Dean Still)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney height, insulation and the pot as heat exchanger
Message-ID: <199808160521.WAA00390@epud.org>

This semester, Summer 1998, the students at Aprovecho and I sought to
investigate what part of the Rocket stove was most responsible for fuel
efficiency. We used a water boil test in which 400 grams of oven dried,
uniform wood was burned at a constant rate. The same type of pot was used
in all tests. It contained 1,000 grams of water.

First, we tested a three stone fire. The average result was 699 grams of
water remaining in the pot after burning all the wood.

Next we tested a simple 4" in diameter 10" tall clay chimney. The wood was
fed into the bottom of the chimney through a 4" in diameter hole cut into
the base of the chimney. This simple stove performed a bit better than the
three stone fire: an average of 520 grams of water remained after the
tests.

Two inches of pumice rock insulation were then placed around the chimney
inside a shiny galvanized sheet metal form that created the outermost body
of the stove. Tests of this stove showed surprisingly little effect due to
the pumice insulation. The average water remaining was 485 grams.

To this stove we then added a metal skirt that surrounded the pot leaving
an approximate gap of ¼ inch between the pot and the skirt. The skirt
resulted in a very considerable improvement. An average of 364 grams of
water was left after the tests.

Finally, three inches of pumice/concrete mixture was added to the original
clay chimney replacing the pumice insulation and sheet metal body. The
mixture was ten parts pumice to one part concrete. When fully dried after a
couple of weeks, we tested this high mass model. 598 grams of water was the
average remaining after the tests.

Then the class tested chimneys of different heights. Although more smoky, a
seven inch high chimney was shown to be the most fuel efficient. Every
added inch of height above 7" resulted in more water remaining. Losses due
to added stove height leveled off at 16". Adding chimney height up to 20"
did not seem to further decrease efficiency.

Conclusions

1.) Chimney height seems to be a very important variable involved in fuel
efficiency. 2.) Insulating around the clay chimney helps a bit but did not
result in great differences. 3.) Instead, a skirt that improves heat
transfer to the pot was shown to make a very great difference. 4.) Even
adding a relatively light weight pumice/concrete three inch thick shell
around the chimney significantly decreased the efficiency of the stove.
Heat was lost into the mass of the shell, making this stove only marginally
more efficient than a three stone fire.

Of course, these results are all from short term tests that reflect most
accurately on short term cooking tasks.

Dean Still
Aprovecho Research Center

From english at adan.kingston.net Sun Aug 16 09:00:22 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:01 2004
Subject: australian outback coffee maker
In-Reply-To: <v01540b09b1f969edae46@[204.133.28.8]>
Message-ID: <199808161310.JAA19798@adan.kingston.net>

Dear Stovers,
Peter Verhart has sent a photo of an "australian outback coffee
maker" which is now displayed at the stoves web site.
Alex

From CKEZAR34 at aol.com Sun Aug 16 13:03:53 1998
From: CKEZAR34 at aol.com (CKEZAR34@aol.com)
Date: Tue Aug 31 21:36:01 2004
Subject: VP and Heat
Message-ID: <61dae181.35d7132b@aol.com>

Researcher Finds Ancient Heat Wave

.c The Associated Press

WASHINGTON (AP) -- A heat wave suddenly moved across Africa some 2,000 years
ago and lasted for centuries before relenting, according to a study of ancient
sediments dredged from the bottom of a mountain lake in Kenya.

Weizman Institute researchers who did the study said their findings show the
global climate naturally goes through cycles of warming and cooling. A current
warming trend has been blamed on greenhouse gasses dumped into the atmosphere
by industry and transportation.

``Our findings show that the climate can warm up suddenly without any
connection to human activity,'' said Aldo Shemesh, head of environmental
sciences at the Weizman Institute in Rehovot, Israel.

A report on the study will be published Friday in the journal Science.

Shemesh said that documenting ancient, natural climate changes will help
modern science more accurately determine the manmade effects on the future
climate.

He and his colleagues gathered sediment cores from the bottom of Hausberg
Tarn, a small lake 14,000 up the side of Mount Kenya. They used a carbon-14
dating technique to determine that some of the bottom material was more than
3,000 years old.

>From the corings, the scientists then extracted fossils of algae that lived
during those ancient times. By analyzing the ratio of two isotopes of oxygen,
they could determine the temperature of the water when the algae lived.

For instance, oxygen-16 is the most common form of oxygen, but the amount of
oxygen-18 in the fossils increases when the water cools and decreases when it
warms.

The researchers found that the waters in Hausberg Tarn suddenly warmed about
seven degrees F between 350 BC and 450 AD. The warming indicates a fundamental
shift in the climate of equatorial East Africa occurred during the period, the
scientists said.

A number of studies in different parts of the world have found evidence of
sudden warming or cooling trends, but the Hausberg Tarn findings are the first
from a high altitude, equatorial location.

AP-NY-08-13-98 1938EDT

Copyright 1998 The Associated Press. The information contained in the AP news
report may not be published, broadcast, rewritten or otherwise distributed
without the prior written authority of The Associated Press. All active
hyperlinks have been inserted by AOL.
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From dstill at epud.org Sun Aug 16 15:15:44 1998
From: dstill at epud.org (Dean Still)
Date: Tue Aug 31 21:36:01 2004
Subject: Reply to Dan Kammen Chimney Height, Insulation, Etc.
Message-ID: <199808161931.MAA01555@epud.org>

Hi Dan,

Well, over the years we have tested a lot of stoves, many brought back by
Aprovecho consultants from around the world. Do you favor a "best stove"
shown to outperform others? Shall I send you a Rocket stove to try or do
you have the one made in Kenya? ( We would love to hear your evaluation.)
If you'd like to send a model we would certainly appreciate it and try to
incorporate parts into our current "bests".

As far as the tests go, the students wanted to try to isolate some of the
variables that make up a good stove. So they chose a simple clay chimney
and built from there. We knew from long and painful experience with the
Lorena (which Aprovecho helped to design and disseminate) that added mass
in the stove body negatively effects fuel efficiency. But, I had taken for
granted that added insulation, like pumice rock, would assist more complete
combustion and boost efficiency. In this case it wasn't shown to be very
valuable. The next semester will test wood ash in the same manner which is
lighter and has a higher R value.

Our thinking constantly constellates around mass and insulation and the
differences between the two. The big advantage of the three stone fire is
that it is very low mass, no stove body diverts heat from the pot. The
chimney stove, however, seems to increase efficiency because 1.) it directs
flame at the pot and 2.) the draft created helps a small fire sustain
itself. The temptation with an open fire is to make a big fire that won't
go out. These two factors seem to overwhelm the disadvantage of the mass of
the light clay chimney.

The good old skirt around the pot has again shown its importance, using
only half the wood as compared to the three stone fire. I always liked the
VITA design that was a skirt around an open fire. The problem was that
without a chimney there was a lot of smoke and not much draft, etc. The 10"
chimney is great because it reduces smoke and helps with complete(r)
combustion. But our experience points out again and again: FUEL EFFICIENCY
IS MUCH MORE DEPENDENT ON IMPROVING HEAT EXCHANGE TO THE POT THAN
INCREASING COMBUSTION EFFICIENCY.

Combustion efficiency is pretty high even in a smokey fire. But a pot by
itself is very bad at getting and holding heat. Increasing the low end of
the equation helps more to raise the overall system efficiency. 70%
combustion efficiency times 10% heat exchanger efficiency equals overall
efficiency of 7%. 90% times 10% equals 9%. But 70% times 30% equals 21%, a
big increase! 90% times 30% equals 27%, etc. Obvious, but I do think that
stove designers tend to think too much about the naturally high end of the
equation...

The variables that the students didn't get to are: the importance of a
shelf to assist creating a grate out of the sticks, making the right shape
on top of the chimney so that a constant cross sectional area is
maintained, adding a feed tube for the wood (should assist preheating),
etc. But most importantly, next semester we will test an open fire where
there is a skirt around the pot which I imagine will show again the
importance of the skirt.

It was the outstanding performance of the skirt that directed our thinking
and led us to acknowledge the ability of a hay box or fireless cooker to be
of the utmost importance for saving fuel and, of course, reducing smoke as
the stove is used for such a short period. We use the hay box every day at
the research center and promote it with confidence.

Thanks,

Dean

From otto at vermontel.com Sun Aug 16 20:03:38 1998
From: otto at vermontel.com (The Otto's)
Date: Tue Aug 31 21:36:01 2004
Subject: Jonathan Otto responding to Cynthia Knowles
In-Reply-To: <v01540b00b1fa91066457@[204.133.28.47]>
Message-ID: <35D79B2A.5AD8@vermontel.com>

Ronal W. Larson wrote:
>
> Stovers: Today, (presently) non-list-member Cynthia Knowles passed this
> information on to Jonahton Otto's message of yesterday in a bounced
> message:
>
> >
> >Dear Jonathon,
> >
> >I posted your letter to the bioenergy list because they may have some
> >suggestions regarding biofuels also. Although I do not have information on
> >cooking stoves fueled by Jatropha oil, we would like to learn more about
> >those oils/fuels derived crops that may be appropriate for pressurized
> >stoves in developing countries. Are you working with wick stoves? We have
> >just completed a cooking needs and stove and fuel use assessment in the
> >Dominican Republic to determine the feasibility of alternatives to fuelwood.
> >We are currently looking into liquid kerosene but have not entered into a
> >pilot stage as of yet. We believe that those who are able to make the
> >switch to a liquid fuel may one day also make a smooth transition to a
> >liquid biofuel, provided that fuel costs are competitive and equipment
> >investment within their means.
> >
> >Do you know of ANY low-cost stoves currently powered by a liquid biofuel?
> >Looking forward to hearing more about your work,
> > Cynthia L. Knowles
> > Enersol Associates, Inc.
> > A Member of
> > The Global Transition Group
> > 55 Middlesex Street, Suite 221
> > North Chelmsford, MA 01863 USA
> > Tel: (978)251-1828/29; Fax: (978)251-5291
> > E-mail: cknowles@igc.apc.org
>
16 August 98

Cynthia and other Stovers,

I'm still getting the hang of this 'list' based communications, so bear
with me if the protocols ain't right. I would love to see your DR
study, and am willing to bet it parallels findings in some African
countries and other areas of biomass shortage. Plant oils will not
solve all domestic energy problems, but it could well be another arrow
in our quiver.

No, I do not know of ANY functioning, low-cost cookstove fueled by
liquid biodiesel. I do have the professional opinion of several
thoughtful engineers that it is certainly possible, but alas, no proof.
The Village Energy Solutions group, working essentially as volunteers
(hope springs eternal in the bleak area of R&D fundraising), has done
most of its experimentation to date with ready-made kerosene wick
stovese, facing predictable problems of limited wicking capacity of more
viscous fuels such as the oils of Jatropha, sunflowerseed, wild borage,
etc. Yes we did modify one inexpensive Chinese kerosene stove to boil
water in a reasonable timespan using Jatropha oil (that stuff burns
clean and hot), but carbon build-up on the wick and other technical
factors convinced us that a purpose-designed plant oil burner is
necessary.

Clearly, pressure or other ways to atomize fuel particles (we had good
success with a more expensive idea that drips a water/oil mix on a
preheated plate) is well worth exploring. In fact a Geneva-based outfit
is currently testing a litre of Jatropha oil that I brought to
Switzerland in a prototype pressure stove that uses height and
manipultion of inlet tube diameter to create pressure. Stay tuned for
results. On another track, a friend of mine at BP in the UK may try to
interest their techies in this problem, but that bureaucracy is
understandably thick. Listen, for all we know, the Coleman Stove
Company solved the problems of low-cost high-viscosity fuel stoves in
the 1930s and shelved the findings for lack of commercial application!
This is why I've fumbled my way onto the internet -- somebody has
probably developed the technology and we might best search before
reinventing it at considerable time and expense.

Thanks for your interest and let's stay in touch,
Jonathan Otto
Village Energy Solutions

From kammen at Princeton.EDU Sun Aug 16 21:20:54 1998
From: kammen at Princeton.EDU (Daniel M. Kammen)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney Height, Insulation, Etc.
Message-ID: <v01530503b1fd43801458@[128.112.71.1]>

Hi Dean,
No, I do not have a 'best stove' favorite -- in Kenya and Uganda we find
too many different fuel/indoor environment/food requirement combinations
to promote a single winner. We do have some of the Rocket-type stoves sold
in Kenya, but your model may be superior.

Of greatest concern in many of the long-term test we have done is the
very significant degradation of some stoves under conditions of real,
and not even 'in house test' usage. I've been looking at a number of
definitions of 'robust efficiency' that try to take the combustion, heat
exchange, and smoke-venting characteristics into account. As part of a
project to test the health and ecological impacts of improved stoves we are
currently
conducting a study with 80 households (~450 people) and a five different
improved wood and charcoal stoves.

It would be very interesting to conduct the series of test you and the Aprovecho
students did over an extended period of usage.

You are also right about the issues of over-loading a stove and thus
reducing the efficiency -- we've seen a number of examples of this in not
only 3-stone fires, but also improved wood and charcoal stove models as
well.

If you are writing up a summary of the student's results, please do send me
a copy.

- Best regards,
Dan

__________________________________________________________________
Daniel M. Kammen
Assistant Professor of Public and International Affairs
Chair, Science, Technology and Environmental Policy (STEP) Program
Woodrow Wilson School of Public and International Affairs
Princeton University
Princeton, NJ 08544-1013
Tel: 609-258-2758
Fax: 609-258-6082
Email: kammen@princeton.edu
WWW: http://www.wws.princeton.edu/~kammen/
Secretary Jackie Schatz:
Tel: 609-258-4821; Email: jackie@wws.princeton.edu
__________________________________________________________________

From btremeer at dds.nl Mon Aug 17 13:12:25 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:01 2004
Subject: Reply to Dan Kammen Chimney Height, Insulation, Etc.
In-Reply-To: <199808161931.MAA01555@epud.org>
Message-ID: <000001bdca03$7c82c720$2f0deed4@blackthorn>

Hi Dean, Dan and stovers

Dean wrote:

>...But our experience points out again and again: FUEL EFFICIENCY
>IS MUCH MORE DEPENDENT ON IMPROVING HEAT EXCHANGE TO THE POT THAN
>INCREASING COMBUSTION EFFICIENCY.

Without a doubt. But it is of utmost importance in my opinion to improve
'heat exchange to the pot' without decreasing combustion efficiency (and
hence increasing emissions). If one 'forces' the flames onto the bottom of
the pot the cold surface seems to 'freeze' the combustion reactions in
half-burned states: the result - noxious fumes.

>The variables that the students didn't get to are: the importance of a
>shelf to assist creating a grate out of the sticks, making the right shape
>on top of the chimney so that a constant cross sectional area is
>maintained, adding a feed tube for the wood (should assist preheating),
>etc. But most importantly, next semester we will test an open fire where
>there is a skirt around the pot which I imagine will show again the
>importance of the skirt.

In a comparison I've made of an open fire, an enclosed insulated single pot
stove, and an open fire built on a grate, I measured efficiencies of 14, 20
and 21 % respectively. Emissions were 15, 43 and 12 grams CO per test
respectively. The efficiency improvement of the enclosed stove I believe was
a result of (much) improved thermal contact combined with a significantly
reduced combustion efficiency. The efficiency improvement for the open fire
built on a grate was a result of improved combustion as well as reduced
losses to the ground. You can find more details of these tests on my
homepage at http://www.energy.demon.nl. Maybe, as well as testing the use of
a skirt you should also try tests of a grate. Naturally, both combined
should give the best of both worlds.

Regards,
Grant

-------------------
Grant Ballard-Tremeer
btremeer@dds.nl; http://www.energy.demon.nl
-------------------

From elk at arcc.or.ke Mon Aug 17 13:53:27 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:36:01 2004
Subject: Oz Kettle
Message-ID: <199808171801.VAA29367@arcc.or.ke>

Ronal asks;

Yes- local artisans can do it. The bottom is easier than the top I'd say-
its a single seam- soldered as in my first galvanised sheet iron kettle, or
electric welded as in my latest stainless steel kettle. Both were made by
'informal' artisans... though the second was an impoerted artisan. He was
Italian.

From btremeer at dds.nl Tue Aug 18 13:58:15 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:01 2004
Subject: Chimney Height, Insulation, Etc.
In-Reply-To: <v01530503b1fd43801458@[128.112.71.1]>
Message-ID: <000401bdcad3$0a42c4a0$2f0deed4@blackthorn>

Greetings
I should have said that the data to which I was referring (as quoted below)
is summarised in appendix E of my thesis. The direct link there is
http://www.energy.demon.nl/AppdxE.htm.
Grant

....quoted from my email of 17/08/98....
>In a comparison I've made of an open fire, an enclosed insulated single pot
stove, and an open fire built on a grate, I >measured efficiencies of 14, 20
and 21 % respectively. Emissions were 15, 43 and 12 grams CO per test
>respectively. The efficiency improvement of the enclosed stove I believe
was a result of (much) improved thermal >contact combined with a
significantly reduced combustion efficiency. The efficiency improvement for
the open fire >built on a grate was a result of improved combustion as well
as reduced losses to the ground. You can find more >details of these tests
on my homepage at http://www.energy.demon.nl.

From english at adan.kingston.net Tue Aug 18 19:12:41 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:01 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <v01530503b1fd43801458@[128.112.71.1]>
Message-ID: <199808182322.TAA18109@adan.kingston.net>

> Greetings
> I should have said that the data to which I was referring (as quoted below)
> is summarized in appendix E of my thesis. The direct link there is
> http://www.energy.demon.nl/AppdxE.htm.

Grant,
Thanks, it is helpful to have the direct link.

In a note from Kirk Smith to Ronal Larson which was forwarded to the
list a few weeks ago, he made the following statement

Kirk Smith wrote on July 11/98. (The full message can be found in the
archives)
> In the full report, I was able to do some calculations that show
> that a stove that truly reduced exposures by 90%, had a lifetime of
> 15 years, and cost $50 (including all the costs of the program such
> as marketing, maintenance, pro-rating over the remaining stoves
> those that failed or did not last the full lifetime, etc.) could
> extend life at a cost of about $30 per life-year extended. This is
> in the range of a number of other health measures now undertaken in
> developing countries (nutrition supplements, tobacco education,
> etc.) although not as cheap as some (vaccinations, AIDS education,
> etc.).

The data in appendix E of your Thesis shows an emission rate for open
fires of 19 g CO per Kg of wood burned and for the shielded one pot
stove, 66 g CO per Kg of wood burned.

Would it follow, that to meet the first of Kirk Smith's criteria, a
stove would have to have an emissions rate of approximately 2 g CO per
Kg of wood burned? ( Assuming an efficiency of at least 20%)

On the same basis, Total Suspended Particulate emissions would have
to be below .08 g per kg of wood burned. That seems like a greater
challenge.

Kirk uses the word "exposure". So I suppose the cooking method
proposed by Dean Still, (start cooking on a stove and finish cooking
in an insulated box, would allow, for example, a stove with twice
the target emissions rate, but burns half as much wood per cooking
task) would also meet the exposure target.

One reason that this approach might have added merit is that it is,
in my opinion, easier to design a "cleaner" combustion dynamic for a
single high (boiling) burn rate than for a variable, max- min,
(boil-simmer) range.

Comments everyone?

Alex

> Grant
>
> ....quoted from my email of 17/08/98....
> >In a comparison I've made of an open fire, an enclosed insulated single pot
> stove, and an open fire built on a grate, I >measured efficiencies of 14, 20
> and 21 % respectively. Emissions were 15, 43 and 12 grams CO per test
> >respectively. The efficiency improvement of the enclosed stove I believe
> was a result of (much) improved thermal >contact combined with a
> significantly reduced combustion efficiency. The efficiency improvement for
> the open fire >built on a grate was a result of improved combustion as well
> as reduced losses to the ground. You can find more >details of these tests
> on my homepage at http://www.energy.demon.nl.
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>

From dstill at epud.org Tue Aug 18 20:03:40 1998
From: dstill at epud.org (Dean Still)
Date: Tue Aug 31 21:36:01 2004
Subject: Reply to Grant Ballard-Tremeer Chimney Height, Insulation, Etc.
Message-ID: <199808190020.RAA10520@epud.org>

Dear Grant,

I read and very much enjoyed your dissertation. Congratulations on a fine
piece of work.

In your experience, is it possible to obtain very clean burning in the
combustion chamber before the flame contacts the pot. Is it possible that
the stove you tested did not achieve very complete combustion? Or does all
flame, dirty or clean, equally freeze and create pollutants?

I am hoping that really clean initial combustion will allow for more
contact between hot flue gases and the pot, better heat exchange, without
increasing harmful emmisions too much, or at all. We've finished two stoves
to be tested so will know more soon. What do you think?

A good sugesstion to test the grate... it is a part of the Rocket stove and
with the other parts previously mentioned I will have the students
separately test each for their importance in efficiency.

Thanks,

Dean

://www.ikweb.com/enuff/public_html/Chamber.htm
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From elk at arcc.or.ke Wed Aug 19 00:34:27 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:36:01 2004
Subject: No Subject
Message-ID: <199808190444.HAA08933@arcc.or.ke>

Alex states;

>... it is,
>in my opinion, easier to design a "cleaner" combustion dynamic for a
>single high (boiling) burn rate than for a variable, max- min,
>(boil-simmer) range.

I agree Alex. Like the choice of carburetors for the same engine- large or
small throat diameter- high rpm power or low rpm torque. I sure that with
simplicity in mind, efficiency is downgraded by flexibility.

But hey, it's great to have goals, no?

From elk at arcc.or.ke Wed Aug 19 01:11:13 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:36:02 2004
Subject: Carbonising Sawdust: Downdraft Kiln Trials
Message-ID: <199808190521.IAA10231@arcc.or.ke>

Stovers;

With reference to my ongoing downdraft sawdust carbonising trials:

Well, the Sawdust carboniser in the first three configurations hasn't
exceeded expectations. A bit below, really, but no surprises. I'm doing the
logical thing considering the data collected, and up-sizing. I'll try
increasing the surface area of the burning beds (m2 of sawdust) while
maintaining the single big chimney (6m X 0.2m). I tried reducing the size of
the bed- this increases the flow of air down through the carbonising
sawdust, but there wasn't a great catalysed leap in burn rate. It's kinda
like potting the optimum on an XYZ graph- where the lines cross is the 'best
fit'. I'm currently collecting little dots and placing them on that chart-
not enough dots to join the lines, step back and see the picture yet........
soon!

I'm up to an air-dried sawdust input rate of 25 kg/hr with a conversion of
24%. This is using a single kiln with a bed of 2.3m diameter. Gasses are
flared, though there is often a bit of light blue smoke indicating
incomplete combustion of volatiles in the burning chamber (photos and
drawings are on the web page).

The sawdust I'm currently using may be too fine- it's from urban woodworking
shops. I'm collecting the large particle size sawdust today- some 7 tons-
from a rural sawmill that 'squares off' logs using a large toothed band saw.
Larger particle size should increase airflow, though the decreased total
surface area attributable to the increased particle size may reduce burn rate.

I'll keep you posted. This work doesn't produce results as quickly at
stove-work!

From larcon at sni.net Wed Aug 19 01:21:04 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:02 2004
Subject: Forwarded: New in Charcoal field - need information on difference !
Message-ID: <v01540b02b1ff58f2f9cc@[204.133.28.45]>

Ramzi: I have signed you up for our "stoves" list. I think your question
is interesting even though very basic. We have concentrated in this list
on manufacture, but your questions on utilization need some discussion as
well. I hope that someone on the list can recommend a few useful
references.
As a brief personal initial response. It seems that there is a
considerable consumer preference for the more dense and larger pieces of
charcoal - that are still able to be lit moderately easily, but do not not
burn out too quickly. I would guess that compressed "briquettes" come
close to optimally meeting consumer preferences - and the amount of added
clay is based on meeting that preference. But I presume such data is
closely held by the briquette manufacturers. Has anyone seen a
"scientific" study on this? Ron

Stovers: Anyone? (Hopefully responding to the full list.)

The rest from "Ramzi Khouri" <ramzikhouri@hotmail.com>

Dear Everybody..

I am very new in the charcoal field and would like to know where to start.

I would like your advice on the availability of web page/ documents /
articles / encyclopedias / etc. on charcoal selection. (Why some crack and
who some do not.. which is better? Why do some light easier than others
and some do not? which is better? What has the type and origin of wood got
to do with quality? etc.)

Well as you can see the type of information needed at this moment is kind
of basic.. I would very much appreciate it if some one can point me in the
right direction.

Thanks and regards

Ramzi Khouri
P. O. Box 1225
Postal Code 112
Sultanate of Oman
Tel +968 932 9647
Fax: +968 794178
"Ramzi Khouri" <ramzikhouri@hotmail.com>

From larcon at sni.net Wed Aug 19 01:21:09 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:02 2004
Subject: Forwarded: Verhaart on Stoves burning vegetable oil
Message-ID: <v01540b03b1ff5e583e49@[204.133.28.45]>

Stovers - I am forwarding the following useful information from list member
Piet Verhaart in reponse to non-list member Cynthia Knowles's message of
the 15th. I hope anyone knowing how to atomise will jump in. I also hope
that Jonathon and others will address Piet's question of why one should
cook with Jatropha or other oils. Would Piet also find fault with using
the oil for lighting and are the combustion issues all the same? The rest
in Piet's words Ron

Both pressurised and wick stoves burning kerosene make use of the fact that
kerosene evaporates completely without decomposing, even under higher than
atmospheric pressure.
Diesel and, more so, vegetable oils decompose on heating before they
evaporate, producing solid and gaseous substances. It follows that when
attempting to use any vegetable oil in a Primus-type burner, it will get
blocked by the carbon deposits. The same applies to wicks, these will have
to have their ends clipped every now and then when their hot ends get
fouled up by carbon deposits.
The way to burn diesel and vegetable oil (though I wonder why anyone should
wish to burn the latter) is to create a jet of finely dispersed oil in
steam or compressed air. It will be a problem to create an atomiser
capable of delivering the minute mass flow of fuel needed for a domestic
size burner.

Piet Verhaart

Peter Verhaart, 6 McDonald St. Gracemere Q 4702 Australia
Phone: +61 7 4933 1761; fax: +61 7 4933 1761 or
+61 7 4933 2112 (when computer is on); mobile: 0412 457239
E-mail p.verhaart@cqu.edu.au

From kchishol at fox.nstn.ca Wed Aug 19 02:19:13 1998
From: kchishol at fox.nstn.ca (Kevin Chisholm)
Date: Tue Aug 31 21:36:02 2004
Subject: Carbonising Sawdust: Downdraft Kiln Trials
In-Reply-To: <199808190521.IAA10231@arcc.or.ke>
Message-ID: <E0z91jC-0007PL-00@mail1.halifax.istar.net>

> Date: Wed, 19 Aug 1998 08:21:01 +0300
> To: stoves@crest.org
> From: elk@arcc.or.ke (E.L.Karstad)
> Subject: Carbonising Sawdust: Downdraft Kiln Trials

Dear Elk

1: Have you measured draft, to confirm whether or not you are getting
more? have you evaluated the benefit of the new stack?

2: Your disappointment may be unjustified; I guess you may have
plugged off your system with the fine sawdust. In general, I feel you may
be choking your system with too deep a bed of fine sawdust

3: Increasing bed area per se will not likely result in improved
performance. HOWEVER, if you go with teh increased area, try a
shallow bed depth. In general, bed depth requirement is proportional
to particle diameter.
4: Your blue smoke condition suggests that you have too much stack
air; it is quenching combustion. Try restricting air to improve
combustion, to raise sytack temp, and to get greater draft.

I think your observations on sawdust particle size are very
important, and that you are likely "more right" by going to a coarser
sawdust, if possible. In general, draft requirements are inversely
proportional to the square of typical particle diameter.

> Stovers;
>
> With reference to my ongoing downdraft sawdust carbonising trials:
>
> Well, the Sawdust carboniser in the first three configurations hasn't
> exceeded expectations. A bit below, really, but no surprises. I'm doing the
> logical thing considering the data collected, and up-sizing. I'll try
> increasing the surface area of the burning beds (m2 of sawdust) while
> maintaining the single big chimney (6m X 0.2m). I tried reducing the size of
> the bed- this increases the flow of air down through the carbonising
> sawdust, but there wasn't a great catalysed leap in burn rate. It's kinda
> like potting the optimum on an XYZ graph- where the lines cross is the 'best
> fit'. I'm currently collecting little dots and placing them on that chart-
> not enough dots to join the lines, step back and see the picture yet........
> soon!
>
> I'm up to an air-dried sawdust input rate of 25 kg/hr with a conversion of
> 24%. This is using a single kiln with a bed of 2.3m diameter. Gasses are
> flared, though there is often a bit of light blue smoke indicating
> incomplete combustion of volatiles in the burning chamber (photos and
> drawings are on the web page).
>
> The sawdust I'm currently using may be too fine- it's from urban woodworking
> shops. I'm collecting the large particle size sawdust today- some 7 tons-
> from a rural sawmill that 'squares off' logs using a large toothed band saw.
> Larger particle size should increase airflow, though the decreased total
> surface area attributable to the increased particle size may reduce burn rate.
>
> I'll keep you posted. This work doesn't produce results as quickly at
> stove-work!
>
>
> elk
> ----------------------------------------------------------------------------
> -----------------------------------------
> Elsen L. Karstad P.O. Box 24371 Nairobi Kenya. Fax (+254 2) 884437 Tel
> 884436, 882375
> ----------------------------------------------------------------------------
> -----------------------------------------
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>
>
>
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From REEDTB at compuserve.com Wed Aug 19 10:25:40 1998
From: REEDTB at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:36:02 2004
Subject: Stove Insulation, Etc.
Message-ID: <199808191035_MC2-5690-74E4@compuserve.com>

Dear Dean:

I am glad to hear that you are conducting research with students on your
Rocket Stove. There are so many possible configurations to test and the
subject is so basic, that it is an ideal subject for student projects. We
may be using testing of our "Turbo Stove" in a similar project here at the
Colorado School of Mines.

I'm also glad to see that you have used a quantitative test to determine
the effect of each change. So much of what we all do is only
semi-quantitattive, giving good impressions, but not measurements.

~~~~~
I was particularly glad to see your use of insulation. I have been beating
on the drum of insulation here at STOVES.CREST for several years with only
minor success. Insulation is always important in high temperature
processes, but particularly if you want to do them small scale like stoves.

In particular I have used RISER sleeves, vacuum formed from
alumina-silicate fibers and resistant to 1500 C heat. You can fire a blow
torch at one side for five minutes and hold your finger on the otherside,
1/2 inch away.

I am curious about your use of PUMICE. Pumice is a volcanic glass and it
is not apparent to me why it should be a good insulator.

I have been experimenting with VERMICULITE. Vermiculite is very low
density steam exploded mica (alumina silicate) and is commonly used as
cheap packing material, for filling plaster, etc. However, yellow heat
(900C) from a torch doesn't cause it to melt and the very low density is
due to trapped air and multiple layers, all important for good insulation.

I have graded the vermiculite with a screen. (How many of you have made
sizing screens from 1 16, 1/8, 1/4, 1/2 inch screens?) I mixed +1/8 -1/4
vermiculite with sodium silicate (water glass) to make a very light weight
insulation that I can trowel on the inside of my cans. So far it seems to
work quite well. I'll report further. I would be interested in any other
experience with vermiculite in this group.

Keep chuggin!

Your stovepal, TOM REED

First, we tested a three stone fire. The average result was 699 grams of
water remaining in the pot after burning all the wood.

Conclusions

1.) Chimney height seems to be a very important variable involved in
fuel
efficiency. 2.) Insulating around the clay chimney helps a bit but did not
result in great differences. 3.) Instead, a skirt that improves heat
transfer to the pot was shown to make a very great difference. 4.) Even
adding a relatively light weight pumice/concrete three inch thick shell
around the chimney significantly decreased the efficiency of the stove.
Heat was lost into the mass of the shell, making this stove only marginally
more efficient than a three stone fire.

Of course, these results are all from short term tests that reflect most
accurately on short term cooking tasks.

Dean Still
Aprovecho Research Center
Message text written by "Dean Still"
>
Dear Grant,

I read and very much enjoyed your dissertation. Congratulations on a fine
piece of work.

A good sugesstion to test the grate... it is a part of the Rocket stove and
with the other parts previously mentioned I will have the students
separately test each for their importance in efficiency.

Thanks,

Dean
<

From REEDTB at compuserve.com Wed Aug 19 10:25:46 1998
From: REEDTB at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:36:02 2004
Subject: Carbonising Sawdust: Downdraft Kiln Trials
Message-ID: <199808191035_MC2-5690-74D7@compuserve.com>

Dear ELK:

Our sympathies for your erratic progress in sawdust charcoal making.

Once you accept that fact that for every two steps forward, you may make
one step back, life goes a lot more smoothly.

I hope you are characterizing the the sawdust properties in your XYZ data
gathering. Moisture content and size are the two most important variables.

We use sawdust to make our product SEA SWEEP, a hydrophobic, oleophilic oil
absorbent, so I have handled many tons of good and bad sawdust and we go
the distance to find a suitable sawdust.

For your purposes and our purposes the best sawdust is rather coarse,
larger than 1 mm max dimension, so that air can pass through for drying and
gasifying/pyrolysing. Unfortunately most of that size sawdust tends to be
50% moisture, first cut sawdust when the trees are still full of water.
Later, after kiln drying, most ofthe sawdust is produced from finer saws
and is dry but small.

Ah me, there is no promise that life will be simpe, but at least we can be
aware of the problems.

Your stovepal, TOM REED

Message text written by E.L.Karstad
>
The sawdust I'm currently using may be too fine- it's from urban
woodworking
shops. I'm collecting the large particle size sawdust today- some 7 tons-
from a rural sawmill that 'squares off' logs using a large toothed band
saw.
Larger particle size should increase airflow, though the decreased total
surface area attributable to the increased particle size may reduce burn
rate.

I'll keep you posted. This work doesn't produce results as quickly at
stove-work!

elk
<

From otto at vermontel.com Wed Aug 19 12:19:34 1998
From: otto at vermontel.com (The Otto's)
Date: Tue Aug 31 21:36:02 2004
Subject: Jatropha oils
Message-ID: <35DB2197.1795@vermontel.com>

Stovers - I am forwarding the following useful information from list
member
Piet Verhaart in reponse to non-list member Cynthia Knowles's message of
the 15th. I hope anyone knowing how to atomise will jump in. I also
hope
that Jonathon and others will address Piet's question of why one should
cook with Jatropha or other oils. Would Piet also find fault with using
the oil for lighting and are the combustion issues all the same? The
rest
in Piet's words Ron

Both pressurised and wick stoves burning kerosene make use of the fact
that
kerosene evaporates completely without decomposing, even under higher
than
atmospheric pressure.
Diesel and, more so, vegetable oils decompose on heating before they
evaporate, producing solid and gaseous substances. It follows that when
attempting to use any vegetable oil in a Primus-type burner, it will get
blocked by the carbon deposits. The same applies to wicks, these will
have
to have their ends clipped every now and then when their hot ends get
fouled up by carbon deposits.
The way to burn diesel and vegetable oil (though I wonder why anyone
should
wish to burn the latter) is to create a jet of finely dispersed oil in
steam or compressed air. It will be a problem to create an atomiser
capable of delivering the minute mass flow of fuel needed for a domestic
size burner.

Piet Verhaart

FROM: Jonathan Otto
Many thanks to Piet Verhaart for his interesting contribution to our
discussion on burning plant oils! I'm not sure he has grasped all the
issues involved (or perhaps I have not grasped his brief comments), so
let me try to further the dialogue a bit. I am certainly NOT an engineer
or technician, but, as they say: this ain't rocket science.

If I understand his point of vegetable oil decomposition during
pre-combusiont heating, my non-technician's question is: so, how can we
aviod preheating the oil to the point at which this happens? Not in a
wick stove perhaps, but I don't see why the pressurizing process would
have to produce such heat levels. As an aside, Jatropha oil has been
used successfully as 'biodiesel' in stationary internal combustion
engines -- the kind that power grinding mills or irrigation systems --
without build-up of excessive deposits inside the engine, and a
colleague of mine adapted his VW Rabbit to use Jatropha oil as fuel,
driving it from Vermont to Michigan and back at better than 50 mpg! Why
would a Primus pressure stove cause carbon deposits if such an engine
doesn't (although finding solution in the stoves case must also meet the
added requirements of extreme economy.)

As to WHY burn vegetable or plant oil, the most obvious need is
environemtal: some 2 billion people still cook with traditional fuels at
great cost in trees and other biomass sources. In may areas, especially
teh semi-arid/sub-tropical zones of Africa, domestic energy development
(firewood, charcoal production) is a leading cause of deforestation.
Kerosene and other petroleum based fuels are simply too expensive for
the vast majority of low-income households, even if they could afford
the stoves required for these fuels. While cooking fuel is the largest
need, kerosene for lighting is also too expensive for millions of
households, although darkness limits many evening activities (homework,
adult education classes), and contributes to the troublesome rural
exodus towards 'city lights' of urban ghettos.

Use of plant oils such as Jatropha as fuel for domestic energy holds out
the promise of locally grown energy that could slow or reverse
environmental degradation. It would also lessen the effort required to
procure fuel which in some areas has become an enormous burden, mainly
on women, and reduces the consumption of cooked meals, boiled drinking
water, and fuel-demanding foods (certain pulses and grains).

In the case of Jatropha curcas, this plant (unpalatable to animals) is
commonly used as a dense hedge to protect and demarcate fields and
farmsteads (preventing animal incursions, reducing wind and run-off
water erosion). It also grows wild on degraded lands, thus taking
little space from cultivation of crops or other uses. While
sunflowerseed oil, groundnut oil, palm oil and other edible oils may
also work in some lighting and heating applications, their caloric value
to humans might best be used for 'internal combusion' of the culinary
variety; hence our emphasis on non-edible, multipurpose perennial
species. May I suggest we use the term 'plant oils' to avoid confusion
with the subset of edible oils often connoted by 'vegetable oils'.
Plesae let me know if this line of thinking is not clear, as it is the
very basis for the entire effort!

Otto

From mheat at mha-net.org Wed Aug 19 16:02:35 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:02 2004
Subject: Stove Insulation, Etc.
In-Reply-To: <199808191035_MC2-5690-74E4@compuserve.com>
Message-ID: <199808192011.QAA23347@tor-smtp1.netcom.ca>

At 10:35 AM 19/08/98 -0400, Tom Reed wrote:
(snip) I would be interested in any other
>experience with vermiculite in this group.
>
Hello everyone:

We have used vermiculite for many years as an aggregate for insulating
castable refractory mixes, using calcium-aluminate cement as a binder. We
can get vermiculite here from our masonry supply yard in various grades -
we use "plaster aggregate" which is fairly fine sized (1/8"). There is also
"concrete aggregate", which is about 1/4". "Block-Fill" or "Zonolite" is
treated with a water repellant, and we avoid those.

We use it in direct contact with flame downstream of the firebox in masonry
heaters, without problems. It softens a bit with use, because calcium
aluminate cement has a temperature "twilight zone", where it loses
strength. We never get it hot enough to get past the twilight zone, where
it strengthens again.

Clay would also make a good binder. A portland cement binder would probably
be good to around 600 F or so.

Best.......Norbert Senf
----------------------------------------
Norbert Senf---------- mheat@mha-net.org
Masonry Stove Builders
RR 5, Shawville------- www.mha-net.org/msb
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092

From english at adan.kingston.net Wed Aug 19 17:29:24 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Carbonising Sawdust: Downdraft Kiln Trials
In-Reply-To: <199808190521.IAA10231@arcc.or.ke>
Message-ID: <199808192139.RAA09873@adan.kingston.net>

>
> Dear Elk
>
> 1: Have you measured draft, to confirm whether or not you are getting
> more? have you evaluated the benefit of the new stack?

Kevin, I guess Elsen just isn't a numbers guy! He probably wets his
finger, holds it up in to the wind, squints at the sun and
decides if its a good day to carbonize.

Alex

From btremeer at dds.nl Wed Aug 19 18:07:55 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808182322.TAA18109@adan.kingston.net>
Message-ID: <000301bdcbbf$18328cc0$2f0deed4@blackthorn>

Dear all

Alex has done some interesting calculations here:
>Kirk Smith wrote on July 11/98. (The full message can be found in the
>archives)
>> In the full report, I was able to do some calculations that show
>> that a stove that truly reduced exposures by 90%, had a lifetime of
>> 15 years, and cost $50 (including all the costs of the program such
>> as marketing, maintenance, pro-rating over the remaining stoves
>> those that failed or did not last the full lifetime, etc.) could
>> extend life at a cost of about $30 per life-year extended. This is
>> in the range of a number of other health measures now undertaken in
>> developing countries (nutrition supplements, tobacco education,
>> etc.) although not as cheap as some (vaccinations, AIDS education,
>> etc.).
>
>The data in appendix E of your Thesis shows an emission rate for open
>fires of 19 g CO per Kg of wood burned and for the shielded one pot
>stove, 66 g CO per Kg of wood burned.
>
>Would it follow, that to meet the first of Kirk Smith's criteria, a
>stove would have to have an emissions rate of approximately 2 g CO per
>Kg of wood burned? ( Assuming an efficiency of at least 20%)
Since Kirk's criteria are exposures, as you point out Alex, the use of a
chimney could also help to achieve the required target. Also proper
ventilation could make a significant contribution to an exposure reduction
of 90%. Often fires are built on the ground which requires the cook to bend
over them... designing a stove at waist level could thus also reduce
exposure. Nonetheless, I think 2g/kg is a pretty useful target to keep in
mind.

>On the same basis, Total Suspended Particulate emissions would have
>to be below .08 g per kg of wood burned. That seems like a greater
>challenge.
There is a little bit of grace here. The value for Total Suspended
Particulates in my thesis is given as grams per test. As an emission factor
(g/kg) it would be 1.1, thus giving a target of 0.11 g per kg of wood
burned. Still a challenge though!

I have done rough calculations (simulations) of CO concentrations in a room
(see http://www.energy.demon.nl/BPCold.htm) which showed that even for the
(relatively) low-emitting open fire, room concentrations after 40 minutes
would be 8 times that recommended as a 15 minute exposure level by the WHO.
This indicates the need for roughly a 90% reduction. I know Kirk Smith has
done proper and thorough exposure measurements which would give a more
reliable indication.

>Kirk uses the word "exposure". So I suppose the cooking method
>proposed by Dean Still, (start cooking on a stove and finish cooking
>in an insulated box, would allow, for example, a stove with twice
>the target emissions rate, but burns half as much wood per cooking
>task) would also meet the exposure target.
The insulated box is great... but requires a new cooking philosophy in my
opinion. I could reduce my gas bill by about 50% if I used it here, but I
don't. If I think about it, most things I cook would need to be adapted to
suit slow cooking. In Southern Africa, the corn (maize) porridge that is the
staple diet for most people is traditionally prepared quickly at a high
temperature with lots of vigorous stirring (after pre-soaking the night
before). In fact, if the bottom of the porridge isn't burnt it is not
considered to be completely cooked... I guess it adds to the flavour. Even
though corn porridge is ideally suited to cooking in a hay box, the
tradition is likely to be long-lasting.

>One reason that this approach might have added merit is that it is,
>in my opinion, easier to design a "cleaner" combustion dynamic for a
>single high (boiling) burn rate than for a variable, max- min,
>(boil-simmer) range.
Yes. The main problem I think is that power is frequently controlled by
varying primary and secondary air inlets rather than fuel feed rate (as is
the practice in my gas stove).

>Comments everyone?
Ditto

Best wishes
Grant

From btremeer at dds.nl Wed Aug 19 18:07:57 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:02 2004
Subject: Reply to Grant Ballard-Tremeer Chimney Height, Insulation, Etc.
In-Reply-To: <199808190020.RAA10520@epud.org>
Message-ID: <000401bdcbbf$19ab7120$2f0deed4@blackthorn>

Dean still wrote:
>In your experience, is it possible to obtain very clean burning in the
>combustion chamber before the flame contacts the pot. Is it possible that
>the stove you tested did not achieve very complete combustion? Or does all
>flame, dirty or clean, equally freeze and create pollutants?

Good questions, and I'm not too sure of the answers. Without a pot the stove
burned fairly cleanly but this is definitely a result of at least three
interacting effects:
1. more time for the reactions to occur
2. no cold surface quenching the flames
3. more secondary air.

If I do a little experiment with a candle (the biggest fire I'm allowed to
light where I'm living), an otherwise clean burning flame goes immediately
smoky when I put a spoon (!) above it but just in contact with the flame.

The flame indicates the burning of volatiles and that means "contact = more
emissions". But I'm open to correction... I know there are many others on
this list more qualified to comment than me...

>I am hoping that really clean initial combustion will allow for more
>contact between hot flue gases and the pot, better heat exchange, without
>increasing harmful emmisions too much, or at all. We've finished two stoves
>to be tested so will know more soon. What do you think?
Yes. I think one wants to get the combustion zone to be as turbulent as
possible, and the should be time for the reactions to occur. It's a good
idea to angle primary and secondary air inlets to create swirl in the
combustion zone.

>A good sugesstion to test the grate... it is a part of the Rocket stove and
>with the other parts previously mentioned I will have the students
>separately test each for their importance in efficiency.
I look forward to hearing the results.

Happy testing
Grant

From dstill at epud.org Wed Aug 19 18:57:44 1998
From: dstill at epud.org (Dean Still)
Date: Tue Aug 31 21:36:02 2004
Subject: Stove Insulation, reply to Tom Reed
Message-ID: <199808192315.QAA15099@epud.org>

Dear Tom:

We have tried light weight pumice rock as insulation, also vermiculite,
perlite, coral rock, rock wool, but the hands down winners are wood ash or
aluminum foil. Wood ash is light, doesn't burn and seems to be highly
insulative creating separate small pockets of air. Much better than pumice
but that's what the Kenyan Rocket is using since it doesn't settle as much.
I'll look for a Riser sleeve, sounds great!! Thanks!

I agree that insulation is very important for creating hot fires and
cutting down on emmissions, also improves draft when used around the
chimney and should help the possibility of secondary combustion. My task in
life seems to be always reminding students of the difference between mass
and insulation.

Keep on stovin',

Dean

From larcon at sni.net Wed Aug 19 23:08:36 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:02 2004
Subject: Forwarding: Peter Verhaart on plant oils
Message-ID: <v01540b05b201448d4c31@[204.133.28.40]>

Stovers: Because of changing addresses, this was bounced to me.

(Piet - I have added your address above, so you will receive two messages;
shall I delete the other given at the end of your message or is the two
address situation temporary?) Ron

Piet said:
>
>Dear Jonathan,
>
> In reply to your comments, I can say the following.
>
>>
>>FROM: Jonathan Otto
>>Many thanks to Piet Verhaart for his interesting contribution to our
>>discussion on burning plant oils! I'm not sure he has grasped all the
>>issues involved (or perhaps I have not grasped his brief comments), so
>>let me try to further the dialogue a bit. I am certainly NOT an engineer
>>or technician, but, as they say: this ain't rocket science.
>>
>>If I understand his point of vegetable oil decomposition during
>>pre-combusiont heating, my non-technician's question is: so, how can we
>>aviod preheating the oil to the point at which this happens? Not in a
>>wick stove perhaps, but I don't see why the pressurizing process would
>>have to produce such heat levels.
>
>Piet
>The pressurising gives the vapour the pressure to flow out of the nozzle
>with sufficient velocity to entrain enough air to give the characteristic
>blue flame of pressurised kerosene burners. If the fuel did not vaporise
>completely, the burner would spit liquid fuel and you get the typical flare
>ups of an insufficiently preheated pressurised burner. It is not the
>pressurising but the essential preheating that produces the temperature
>necessary for evaporation.
>
>>As an aside, Jatropha oil has been used successfully as 'biodiesel' in
>stationary >internal combustion engines -- the kind that power grinding
>mills or irrigation >systems -- without build-up of excessive deposits
>inside the engine, and a
>>colleague of mine adapted his VW Rabbit to use Jatropha oil as fuel,
>>driving it from Vermont to Michigan and back at better than 50 mpg! Why
>>would a Primus pressure stove cause carbon deposits if such an engine
>>doesn't (although finding solution in the stoves case must also meet the
>>added requirements of extreme economy.)
>
>Piet
>As I mentioned, regular diesel fuel also decomposes when heated at
>atmospheric pressure. That is the reason it is injected into the combustion
>space of the engine in the form of finely divided LIQUID droplets. To this
>end the liquid is brought to a very high pressure and escapes through a
>thin circular slit or through a series of very small holes.
>
>You make a point for burning non edible plant oils. Still I think the oil
>could be kept for lighting. Commonly the amount of waste plant mass is a
>multiple of the mass of oil produced, so some thought might be given to
>find efficient ways to burn it in cookstoves.
>
>>As to WHY burn vegetable or plant oil, the most obvious need is
>>environemtal: some 2 billion people still cook with traditional fuels at
>>great cost in trees and other biomass sources. In may areas, especially
>>teh semi-arid/sub-tropical zones of Africa, domestic energy development
>>(firewood, charcoal production) is a leading cause of deforestation.
>>Kerosene and other petroleum based fuels are simply too expensive for
>>the vast majority of low-income households, even if they could afford
>
>>the stoves required for these fuels. While cooking fuel is the largest
>>need, kerosene for lighting is also too expensive for millions of
>>households, although darkness limits many evening activities (homework,
>>adult education classes), and contributes to the troublesome rural
>>exodus towards 'city lights' of urban ghettos.
>>
>>Use of plant oils such as Jatropha as fuel for domestic energy holds out
>>the promise of locally grown energy that could slow or reverse
>>environmental degradation. It would also lessen the effort required to
>>procure fuel which in some areas has become an enormous burden, mainly
>>on women, and reduces the consumption of cooked meals, boiled drinking
>>water, and fuel-demanding foods (certain pulses and grains).
>>
>>In the case of Jatropha curcas, this plant (unpalatable to animals) is
>>commonly used as a dense hedge to protect and demarcate fields and
>>farmsteads (preventing animal incursions, reducing wind and run-off
>>water erosion). It also grows wild on degraded lands, thus taking
>>little space from cultivation of crops or other uses. While
>>sunflowerseed oil, groundnut oil, palm oil and other edible oils may
>>also work in some lighting and heating applications, their caloric value
>>to humans might best be used for 'internal combusion' of the culinary
>>variety; hence our emphasis on non-edible, multipurpose perennial
>>species. May I suggest we use the term 'plant oils' to avoid confusion
>>with the subset of edible oils often connoted by 'vegetable oils'.
>>Plesae let me know if this line of thinking is not clear, as it is the
>>very basis for the entire effort!
>>
>>Otto
>
>Hope this makes things somewhat clearer.
>Regards,
>
>Piet
>
>>
>>
>>Stoves List SPONSORS and ARCHIVES:
>>http://solstice.crest.org/renewables/stoves-list-archive/
>>Stoves Webpage
>>http://www.ikweb.com/enuff/public_html/Stoves.html
>>For information about CHAMBERS STOVES
>>http://www.ikweb.com/enuff/public_html/Chamber.htm
>>
>Peter Verhaart, 6 McDonald St. Gracemere Q 4702 Australia
>Phone: +61 7 4933 1761; fax: +61 7 4933 1761 or
>+61 7 4933 2112 (when computer is on); mobile: 0412 457239
>E-mail p.verhaart@cqu.edu.au
>

From elk at arcc.or.ke Thu Aug 20 00:49:39 1998
From: elk at arcc.or.ke (E.L.Karstad)
Date: Tue Aug 31 21:36:02 2004
Subject: Carbonising Sawdust- Downdraft Kiln Stack
Message-ID: <199808200459.HAA03668@arcc.or.ke>

>> 1: Have you measured draft, to confirm whether or not you are getting
>> more? have you evaluated the benefit of the new stack?
>
>Kevin, I guess Elsen just isn't a numbers guy! He probably wets his
>finger, holds it up in to the wind, squints at the sun and
>decides if its a good day to carbonize.
>
>Alex
-------------------------------

Alex is right- I'm not using tools to measure the specific parameters of my
apparatus. This may come in handy further down the road for fine tuning, but
at the moment I find a weigh scale is all I need in addition to my angle
grinder and electric welder, not to mention my team of enthusiastic artisans.

The new chimney certainly has helped- doubling diameter and adding a third
to height has nearly doubled the rate of carbonisation keeping the kiln size
constant.

The stack diameter of 20 cm and height of 6 m. is a manageable size now.
Much larger and materials and manuf. cost will become impractical, so I'll
work with this as long as I can dream up permutations to try.......

Next trials are on larger particle sized sawdust. All sawdust is air dried
completely- to between 10 & 15% moisture.

Following this, I'm doubling kilns to 2 kilns of 2m diam. Both will be
connected to the same single chimney.

Sqinting in the wind............

From mheat at mha-net.org Thu Aug 20 05:43:13 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808182322.TAA18109@adan.kingston.net>
Message-ID: <Version.32.19980820034959.00f0c100@mha-net.org>

At 12:17 AM 20/08/98 +0200, Grant Ballard-Tremeer wrote:
(snip)
>Particulates in my thesis is given as grams per test. As an emission factor
>(g/kg) it would be 1.1, thus giving a target of 0.11 g per kg of wood
>burned. Still a challenge though!
>

Using EPA (US Environmental Protection Agency) Method 5 for wood space
heaters, 1.1 g/kg would be a very low number. The EPA PM-10 standard is 7.5
g/hr, which would translate to 7.5 g/kg at a 1 kg/hr burn rate. By
comparison, old technology woodstoves, where the critical burn rate (the
point at which smoldering combustion happens) is higher, have emissions
roughly in the 15 g/hr range.

We did extensive particulate emissions testing on high mass heaters
(masonry heaters), and got emissions down to the 1 g/kg range when
everything was working well. I would consider 0.1 g/kg to be unobtainable
without, at minimum, resorting to things like microprocessor controlled
air supplies and forced draft.

ONe of the problems with particulate measurements is their unstable and
variable nature. If you extract hot gas and filter it, for example,
uncondensed volatiles will blow right through the filter, thus giving you
an artificially low number. I believe that opacity measurements would have
the same problem. There are a number of ways around this - the easiest
being to dilute the exhaust with air, thereby cooling it and condensing the
tars, and then collecting the condensed particulates on a filter. We use a
simple device known as a Condar dilution tunnel, which is quite portable
and fairly low tech. The required high tech components are an O2 or CO2
analyzer and a laboratory balance with a resolution of .0001 gram for
weighing the filters.

In the German masonry heater literature, I have seen references to "staub",
literally "dust", which may be confused with particulates. I believe that
they filter the hot gases, and from the typical numbers quoted for masonry
heaters, I am reasonably sure that they are measuring soot only, not
condensible volatiles.

The EPA standard is the only one that I have seen to date that gives a
reference method for wood smoke particulates. The other interesting aspect
that we have noted, at the low end of the emissions scale, is a very low
correlation between PM and CO. When burning in batch mode in a masonry
heater, there is a characteristic CO spike during the cold start, that can
be mitigated in various ways. There is another, unavoidable, spike at the
end during the charcoal phase, when particulates are non-existent. Hence,
the CO-PM relationship is tenuous at best. An interesting aspect is that
European emissions regulations for woodstove are based on CO and NOX,
whereas North American standards are based on PM, thus guaranteeing
incompatibility. A "clean burning" stove in Europe is not necessarily
clean-burning in North America, and vice-versa.

Best.......Norbert Senf

----------------------------------------
Norbert Senf---------- mheat@mha-net.org
Masonry Stove Builders
RR 5, Shawville------- www.mha-net.org/msb
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092

From english at adan.kingston.net Thu Aug 20 08:07:58 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Reply to Grant Ballard-Tremeer Chimney Height, Insulation, E
In-Reply-To: <199808190020.RAA10520@epud.org>
Message-ID: <199808201208.IAA00034@adan.kingston.net>

Dear Dean, Grant and all,

> Yes. I think one wants to get the combustion zone to be as turbulent as
> possible, and the should be time for the reactions to occur. It's a good
> idea to angle primary and secondary air inlets to create swirl in the
> combustion zone.

An example of this would be the Swosthee Stove developed in India.
I think there are a few variations of it. Unfortunately I have not
seen any of them. Last year Piet Verhart sent me some sectional
drawings of one of them, which I have just renewed on the stoves
webpage. Check it out under the NEW.

It would be interesting to know how much swirl it is able to generate
by having all its air introduced tangentially with only 18cm of
chimney height.

The role of ' swirl' overlaps that of insulation. It
can speed up, compact, stabilize flames, and ultimately raise the
temperature of the combustion zone. Of equal importance would be
minimizing the of amount of excess air diluting the mix. Excess air
which reduces residence time, absorbs heat and lowers peak combustion
chamber temperatures.

That's all easier said than done while burning solid fuel. While
burning the pyrolysis gasses from 'top down' charcoal making it is
possible to do this with a few feet of chimney as a minimum. The
pyrolysis gasses represent 20 -40% of the mass flowing through the
stove at low velocity, resulting in low vertical momentum. The
majority of the total mass flow is introduced as secondary air at
higher velocity, horizontally, with much higher momentum, to drive
the swirl.

It would make for interesting modeling to find the optimum
configuration.

Even without insulation, the burner I have been using is able to
operate with very clean combustion. An insulated low mass combustion
chamber would help the most during start up.

As I back up from what works, to what is practical, I can see the
insulation being a bigger issue.

Spinning in circle, Alex

> Happy testing
> Grant

From english at adan.kingston.net Thu Aug 20 11:32:00 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Chimney height, insulation and the pot as heat exchanger
In-Reply-To: <199808160521.WAA00390@epud.org>
Message-ID: <199808201541.LAA18523@adan.kingston.net>

Dean,
With regards to your reported test burns:
Could you tell me about how long these individual test took? And what
were the dimensions of the "uniform" pieces of wood?
Thanks, Alex

> This semester, Summer 1998, the students at Aprovecho and I sought to
> investigate what part of the Rocket stove was most responsible for fuel
> efficiency. We used a water boil test in which 400 grams of oven dried,
> uniform wood was burned at a constant rate. The same type of pot was used
> in all tests. It contained 1,000 grams of water.
>
> First, we tested a three stone fire. The average result was 699 grams of
> water remaining in the pot after burning all the wood.
>
> Next we tested a simple 4" in diameter 10" tall clay chimney. The wood was
> fed into the bottom of the chimney through a 4" in diameter hole cut into
> the base of the chimney. This simple stove performed a bit better than the
> three stone fire: an average of 520 grams of water remained after the
> tests.
>
> Two inches of pumice rock insulation were then placed around the chimney
> inside a shiny galvanized sheet metal form that created the outermost body
> of the stove. Tests of this stove showed surprisingly little effect due to
> the pumice insulation. The average water remaining was 485 grams.
>
> To this stove we then added a metal skirt that surrounded the pot leaving
> an approximate gap of ¼ inch between the pot and the skirt. The skirt
> resulted in a very considerable improvement. An average of 364 grams of
> water was left after the tests.
>
> Finally, three inches of pumice/concrete mixture was added to the original
> clay chimney replacing the pumice insulation and sheet metal body. The
> mixture was ten parts pumice to one part concrete. When fully dried after a
> couple of weeks, we tested this high mass model. 598 grams of water was the
> average remaining after the tests.
>
> Then the class tested chimneys of different heights. Although more smoky, a
> seven inch high chimney was shown to be the most fuel efficient. Every
> added inch of height above 7" resulted in more water remaining. Losses due
> to added stove height leveled off at 16". Adding chimney height up to 20"
> did not seem to further decrease efficiency.
>
> Conclusions
>
> 1.) Chimney height seems to be a very important variable involved in fuel
> efficiency. 2.) Insulating around the clay chimney helps a bit but did not
> result in great differences. 3.) Instead, a skirt that improves heat
> transfer to the pot was shown to make a very great difference. 4.) Even
> adding a relatively light weight pumice/concrete three inch thick shell
> around the chimney significantly decreased the efficiency of the stove.
> Heat was lost into the mass of the shell, making this stove only marginally
> more efficient than a three stone fire.
>
> Of course, these results are all from short term tests that reflect most
> accurately on short term cooking tasks.
>
> Dean Still
> Aprovecho Research Center
>
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>

From english at adan.kingston.net Thu Aug 20 23:01:35 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <000301bdcbbf$18328cc0$2f0deed4@blackthorn>
Message-ID: <199808210311.XAA13332@adan.kingston.net>

Hi Norbert,
I fear that Grant has travelled off, unable to defend his protocol
just now.
So forgive me while I beat a familiar drum in the context of some of
your comments.

> Using EPA (US Environmental Protection Agency) Method 5 for wood space
> heaters, 1.1 g/kg would be a very low number. The EPA PM-10 standard is 7.5
> g/hr, which would translate to 7.5 g/kg at a 1 kg/hr burn rate. By
> comparison, old technology woodstoves, where the critical burn rate (the
> point at which smoldering combustion happens) is higher, have emissions
> roughly in the 15 g/hr range.

In that context, it sounds like an impossible challenge.
The chunk or block wood burners like EPA stove and your masonry
heaters have similar fuel type limitations in common. What is most
appropriate for the people who use wood heat in wealthy countries is
perhaps least appropriate for cooking a meal in materially
poor regions of the world. The twigs and branches that are left in
the forests of the North resemble the first choice fuel for cooking
in the South. This difference in fuel may be the key to developing a
successful low emissions stove. The top down pyrolyser arrangement
offers the potential for a completely different, low emission,
paradyme for burning wood. One who's only application may in fact be
cooking in developing countries. Instead of constant burn rate change
typical of manually stoked chunk wood fires, this method approaches
the" burn" rate continuity of mechanically stoked pellet or chip
burners, albeit over a shorter total span consistent with the batch
load of fuel. With a steady fuel supply in the form of combustible
pyrolysis gasses and suspended liquid droplets, the approach to
combustion can be more precise than that of chunk burners. More
similar to an oil burner.

> We did extensive particulate emissions testing on high mass heaters
> (masonry heaters), and got emissions down to the 1 g/kg range when
> everything was working well. I would consider 0.1 g/kg to be unobtainable
> without, at minimum, resorting to things like microprocessor controlled
> air supplies and forced draft.

While experiencing some variability due to rough prototype and
process irregularities, I have seen ample evidence that air supplies
can be maintained in a satisfactory range without much difficulty.
Only three feet of chimney draft is required to enhance mixing to
the point of yielding a CO/CO2 ratio that, not to infrequently,
drops to 0.0002. I have even seen the burner, with no enhanced
swirl, due to limited total chimney height, maintain a ratio of
.0025 while boiling a pot full of water.

>
> The other interesting aspect
> that we have noted, at the low end of the emissions scale, is a very low
> correlation between PM and CO. When burning in batch mode in a masonry
> heater, there is a characteristic CO spike during the cold start, that can
> be mitigated in various ways. There is another, unavoidable, spike at the
> end during the charcoal phase, when particulates are non-existent. Hence,
> the CO-PM relationship is tenuous at best.

I would like to know more about this. Perhaps I need one of these
Condar dilution tunnels to do my own experiments. I feel that this
example that you give is not very transferable to the circumstances I
discribe. CO-PM are both products of incomplete combustion. The same
parameters are juggled to reduce both in oil burners. (Someone
correct me if I am wrong) I would be interested if someone can give
an example of a combustion dynamic which has extremely low CO and high
PM10. Especially an example which has some relation to this
circumstance.
It is for these reasons that I hold out hope for an acceptably low
emissions cooking stove.

There are lots of other pluses and minuses to this approach which
I'll hold back on. I feel the potential is there, what is needed is
more development. A concerted effort could produce some exciting
results.

Ron would be upset if I didn't mention the best part of all.
The cook can produce a saleable product, charcoal.

And by the way Norbert. I appreciate your willingness to share your
considerable knowledge and experience.

On my learning way, Alex

>
> Best.......Norbert Senf
>
> ----------------------------------------
> Norbert Senf---------- mheat@mha-net.org
> Masonry Stove Builders
> RR 5, Shawville------- www.mha-net.org/msb
> Quebec J0X 2Y0-------- fax:-----819.647.6082
> ---------------------- voice:---819.647.5092
>
>
>
>
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>
Alex English
RR 2 Odessa Ontario
Canada K0H 2H0
Tel 1-613-386-1927
Fax 1-613-386-1211
Stoves Webpage

From mheat at mha-net.org Fri Aug 21 07:08:33 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <Version.32.19980820034959.00f0c100@mha-net.org>
Message-ID: <199808211118.HAA10783@tor-smtp2.netcom.ca>

At 11:09 PM 20/08/98 -0500, Alex English wrote:
(snip) With a steady fuel supply in the form of combustible
>pyrolysis gasses and suspended liquid droplets, the approach to
>combustion can be more precise than that of chunk burners. More
>similar to an oil burner.

Hi Alex:
Thank you for enlightening me. I've followed the rural cooking stove scene
on and off over the years, but was in the dark as far as their emissions
performance. I did have the opportunity of downloading Grant's excellent
thesis (after making my comments, of course), and note that one of his
reference fires is an open fire - in my mind I picture this as smokey,
certainly nothing in the 1 g/kg PM range.

>> We did extensive particulate emissions testing on high mass heaters
>> (masonry heaters), and got emissions down to the 1 g/kg range when
>> everything was working well. I would consider 0.1 g/kg to be unobtainable
>> without, at minimum, resorting to things like microprocessor controlled
>> air supplies and forced draft.
>
>While experiencing some variability due to rough prototype and
>process irregularities, I have seen ample evidence that air supplies
>can be maintained in a satisfactory range without much difficulty.
>Only three feet of chimney draft is required to enhance mixing to
>the point of yielding a CO/CO2 ratio that, not to infrequently,
>drops to 0.0002. I have even seen the burner, with no enhanced
>swirl, due to limited total chimney height, maintain a ratio of
>.0025 while boiling a pot full of water.

That's pretty good, compared to chunk burners. For a masonry heater, really
clean would be .001, but that would be over the whole burn cycle, including
cold start and charcoal phase.

>>
>> The other interesting aspect
>> that we have noted, at the low end of the emissions scale, is a very low
>> correlation between PM and CO. When burning in batch mode in a masonry
>> heater, there is a characteristic CO spike during the cold start, that can
>> be mitigated in various ways. There is another, unavoidable, spike at the
>> end during the charcoal phase, when particulates are non-existent. Hence,

>> the CO-PM relationship is tenuous at best.
>
>I would like to know more about this. Perhaps I need one of these
>Condar dilution tunnels to do my own experiments. I feel that this
>example that you give is not very transferable to the circumstances I
>discribe.

Probably not - the burn regimes seem to be quite different. We have so much
wood in the firebox (20 kg) that we need big pieces to keep the surface to
volume ratio in a region where we can get enough air to the fire,
particularly at the beginning before a char layer has developed on the
chunks to help slow things down. With softwoods, 3 meter long flames are
not uncommon. 50% of the PM emissions are during the 5 -10 minute cold
start (the EPA protocol for continuous-burn stoves ignores this aspect by
using a hot-to-hot burn cycle).

CO-PM are both products of incomplete combustion. The same
>parameters are juggled to reduce both in oil burners. (Someone
>correct me if I am wrong) I would be interested if someone can give
>an example of a combustion dynamic which has extremely low CO and high
>PM10. Especially an example which has some relation to this
>circumstance.

This is an argument that we have with the Europeans regarding emissions
regs. They don't have any problem with CO as an indicator of PM. Here in
North America (for better or worse) the argument is that PM (smoke) is the
problem, from a public health standpoint, so that is what you have to
measure, even though it is a lot more difficult. While CO and PM are indeed
both indicators of incomplete combustion, no one to my knowledge has ever
established a convincing correlation.

When the first batch of EPA-certified stoves came out, it turned out that
they were tuned to the laboratory fueling protocol, and their field
performance was disappointing. As a result, a number of in-home studies
were funded, using portable field samplers developed at OMNI Environmental
(the late Dr. Skip Barnett) in Oregon and at Virginia Polytechnic (Dr.
Dennis Jaasma)

>It is for these reasons that I hold out hope for an acceptably low
>emissions cooking stove.

That sounds very exciting. I would love to know how Grant's opacity
measurements for PM correlate with EPA M-5, since my first question is
whether the two methods are even in the same ballpark or not (I have no
idea at this point). I have no doubt that the opacity method would be valid
in a relative sense (comparing one stove with another using the same
protocol). It certainly seems to be a lot easier. The most feasible
approach would probably be to run a Condar in parallel with an opacity
meter. The downside of the Condar is that it samples off a flue pipe, ie.,
before there is any dilution.

The Condar itself is quite simple and elegant. It was developed by Skip
Barnett, and was almost accepted as an EPA method except for some politics.
It is an official method in Oregon (Oregon Method 41). A calibrated 3/8"
nozzle draws effluent from the stack. An arrangement of holes mixes in air
at 10:1. A vaccum cleaner motor on a rheostat provides constant suction to
draw a fixed flow through a 6" fiberglass filter. A manometer measures the
vacuum in the chamber, and the motor speed is adjusted from time to time
to keep the vacuum constant as the filter is loaded. Filters can be changed
frequently for semi real-time measurements.

If anyone is able to burn fuelwood reliably at below 1 g/kg, in a
cold-to-cold test, that would be news, in my opinion. There is no way to
know, however, unless a test method is referenced to EPA M-5. PM is a very
slippery measurement, and some standard has to be agreed on.

Best.......Norbert
----------------------------------------
Norbert Senf---------- mheat@mha-net.org
Masonry Stove Builders
RR 5, Shawville------- www.mha-net.org/msb
Quebec J0X 2Y0-------- fax:-----819.647.6082
---------------------- voice:---819.647.5092

From english at adan.kingston.net Fri Aug 21 07:18:01 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Pictures of Swosthee Stoves
Message-ID: <199808211128.HAA04239@adan.kingston.net>

Dear Stovers,
Auke Koopmans has sent a few pictures of the Swosthee Stove, which
are now added to the web page.

I understand that this is a highly engineered stove. There must be
additional information available related to it's function,
efficiency and emissions, that would be useful to list members.

Alex

From english at adan.kingston.net Fri Aug 21 22:57:02 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808210311.XAA13332@adan.kingston.net>
Message-ID: <199808220307.XAA07719@adan.kingston.net>

Norbert,
Thanks for all the information on PM measurement. If you are ever
testing and could tolerate an observer, I would drive up.

> For a masonry heater, really clean would be .001, but that would
> be over the whole burn cycle, including
> cold start and charcoal phase.

I would like to see the real, and semi real time, data for your
burns.

I have been pondering some simple experiments which could test PM
and CO correlation for fairly "clean" and controlled combustion. I
took a kerosene lamp (which I have found to be a reliable producer
of CO for an instrument check) and monitored its performance at two
distinct settings. CO/CO2 at low light (.5" tall flame) was .003.
At high light, ( 1.25") .001. There was no visible smoke at either
setting. If PM could be measured, (not that easy?) it might provide
some perspective on the question. A better test might involve
manipulating a few parameters on a good pellet burner.

Just a thought, Alex

> Best.......Norbert
> ----------------------------------------
> Norbert Senf---------- mheat@mha-net.org
> Masonry Stove Builders
> RR 5, Shawville------- www.mha-net.org/msb
> Quebec J0X 2Y0-------- fax:-----819.647.6082
> ---------------------- voice:---819.647.5092
>
>
>
>
>
> Stoves List SPONSORS and ARCHIVES:
> http://solstice.crest.org/renewables/stoves-list-archive/
> Stoves Webpage
> http://www.ikweb.com/enuff/public_html/Stoves.html
> For information about CHAMBERS STOVES
> http://www.ikweb.com/enuff/public_html/Chamber.htm
>
>

From mheat at mha-net.org Sat Aug 22 07:33:38 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808211118.HAA10783@tor-smtp2.netcom.ca>
Message-ID: <Version.32.19980822052726.00f09490@mha-net.org>

At 11:05 PM 21/08/98 -0500, you wrote:
>Norbert,
>Thanks for all the information on PM measurement. If you are ever
>testing and could tolerate an observer, I would drive up.

Hi Alex:

Unfortunately, we aren't set up here for PM testing. We have a sister test
facility in Seattle, at Jerry Frisch's shop, and Jerry has the Condar
setup. Neither of us has done any testing for awhile. We have an annual
Masonry Heater Association meeting in North Carolina in April, and I might
try to set something up for there, since the Condar and my gas analyzer are
portable -- filters could simply be weighed at the lab, to avoid having to
transport the balance. It seems to me that it would be very worthwhile to
find out if there is a correlation between Oregon M-41 and opacity. If
there is, we could all be saving ourselves a lot of trouble.

>> For a masonry heater, really clean would be .001, but that would
>> be over the whole burn cycle, including
>> cold start and charcoal phase.
>
>I would like to see the real, and semi real time, data for your
>burns.

We have a lot of it online. The data is in Excel spreadsheets, at the
following location:

http://mha-net.org/msb/html/lop-arc.htm#Data

Let me know if you are successful in loading it, and I can explain it a
little further.

>I have been pondering some simple experiments which could test PM
>and CO correlation for fairly "clean" and controlled combustion. I
>took a kerosene lamp (which I have found to be a reliable producer
>of CO for an instrument check) and monitored its performance at two
>distinct settings. CO/CO2 at low light (.5" tall flame) was .003.
> At high light, ( 1.25") .001. There was no visible smoke at either
>setting. If PM could be measured, (not that easy?) it might provide
>some perspective on the question. A better test might involve
>manipulating a few parameters on a good pellet burner.

My gut feeling is that the correlation simply isn't there, except perhaps
for a few very controlled scenarios (advanced cooking stoves just might be
one of them, however). Although I'm very far from being an expert, my
browsing of the literature on pyrolysis etc., tells me that wood combustion
chemistry is extremely complicated, compared to fossil fuel combustion.
There are so many interactions and possible chemical pathways that it makes
the mind spin. From my observations with cordwood, there seem to be two
main CO sources: fuel-rich, unmixed, cold conditions at startup, when
volatiles predominate, and charcoal burning at the end.

The first phenomenon is quite variable, and almost identical initial
conditions (in a masonry heater) can bifurcate into either a big CO spike
or not. The Austrian stovebuilders call this "umkippen der Verbrennung",
literally, the burn "tips over".

The charcoal phase is quite different, and CO simply is a characteristic,
whereas PM is absent - there is your high CO/low PM scenario.

So, burning large (150 mm dia) cordwood in batch mode, we have a kind of
two part burn - lots of volatiles, followed by a charcoal fire. The CO/PM
relationships are quite different for the two parts, so adding them
together and trying to draw correlations probably won't get you very far -
you'd probably at least have to separate out the two parts of the burn.

One of the things that has impressed me is how much this whole scenario is
dominated by geometry - fuel shape, relationship of pieces in the stack,
kindling progression, etc. In an oil burner, by contrast, you have a steady
state, much simplified condition. A pellet stove seems closer to an oil
burner than a cordwood fire. Not sure where your cookstoves would be on
this scale.

After testing for awhile, we noticed a few things. If we saw smoke from
the chimney, this was a pretty good indicator that we'd get higher PM, so
I'm hopeful for being able to use opacity. When we checked the filters we
made the following observations: The smell of the filter could be
categorized into 3 distinct types: "none", "campfire", and "creosote".
"None" indicated soot and the filter would be very black and lightweight.
"Creosote" indicated tars, and the filter would be yellow and heavy.
"Campfire" was an intermediate state. Similarly, black smoke (as you would
get from a dirty oilburner) indicates soot, and blue smoke indicates tar. I
believe the blue color is due to light refraction and the small size of the
tar droplets (in the 1 micron range). With a masonry heater, we also have
to differentiate white smoke, which is condensed water vapour.

The other interesting result came from field studies conducted by OMNI.
When the PM from a masonry heater burning in the 1 g/kg range was analyzed,
60% of it was non-soluble (ie., soot and a little fly ash), indicating that
as the PM number gets lower, the fraction of VOC's probably gets lower too,
which is good news from a health standpoint. This is confirmed by some
earlier test results from Austria, where a detailed PAH analysis was done
on two types of heater (clean and dirty).

Best..........Norbert

From larcon at sni.net Sat Aug 22 09:24:11 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:02 2004
Subject: Forwarding from ITDG on Past Stoves Conferences
Message-ID: <v01540b01b203b63b5da2@[204.133.28.39]>

Stovers: The following message just in from list member Smail Khennas from
ITDG in response to a message some weeks ago trying to find past stoves
conferences. This conference information (and this is the first I am aware
of) can be very helpful to Ms. Priyadarshini Karve as she strives to find
support for the January 2000 stoves conference to be held in Pune, India.

Does anyone else have anything similar to report?

Smail: Thank you very much for this forwarding, I shall try to locate
copies at our National Renewable Energy Laboratory (NREL). Do you (or
anyone on the list) have copies of their final reports?

A few more questions on each below:

>Dear stover,
>I am not a technical person, it is why I don't interfere in your
>discussions related to these aspects. However I am quite interested
>in some results.
>With respect to past stoves conferences, I would like to mention a
>couple of interesting fora:
>
>1- Stoves for people, International workshop,
>Guatemala 4-10 October 87 ( more than 30 presentations about 30 % in
>French). Interesting papers addressing both technical and socio
>economic aspects FWD ( 2 volumes)

Smail: I gather that FWD was the sponsor? Does ITDG have a copy?
Presumably many articles also in Spanish? The number in English? Might
you or anyone now at ITDG have gone? Possibly still available from FWD?

Others: Anyone on the list go to this conference? The list of
authors and their affiliations could be very helpful in getting experienced
persons to come to Pune (with travel support being hoped for and maybe even
likely). Anyone have a good tie now to FWD?

>
>2- First International Symposium on fuel efficient stoves
>9-12 October 86 Beijing China, China Machine press publisher. Only
>technical papers. ( 155 pages) Certainly very useful for you.

Smail or others: What language for this volume? Do you think this
might still be available? Do you have a copy?

>
>Some conferences were organized more recently particularly in West
>Africa but I don't have the references.
>
>Hope this information is useful.
>
(Larson): Yes indeed. Thanks for passing this on. I hope others
will help if they can, similarly
.
>
>Dr Smail Khennas
>Senior Energy Specialist
>Intermediate Technology
>The Schumacher Centre for Technology and Development
>Bourton Hall
>Bourton on Dunsmore, Rugby
>Warwickshire
>CV23 9QZ
>Tel +44-1788-661 100
>Fax: +44 -1788 44-(0)1788-661 101
>Email: smailk@itdg.org.uk
>Url: http://www.oneworld.org/itdg
>Url:http://www.itdg.org.pe
>Company Reg No 871954, England
>Charity No 247257
>

From dstill at epud.org Sun Aug 23 18:06:51 1998
From: dstill at epud.org (Dean Still)
Date: Tue Aug 31 21:36:02 2004
Subject: Pictures of Swosthee Stoves
Message-ID: <199808232226.PAA27873@epud.org>

Dear Alex,

I sure would like to hear from the designers of the Swosthee Stove. We had
built a stove along the same lines for testing, trying to mix up preheated
air entering the combustion chamber and the flames did swirl around.

This design seems to create a lot of preheating and I wonder: How hot is
the air? Where does the air enter the combustion chamber and does the
conical chimney improve "secondary combustion" or draft? Do all models have
such a small opening for fuel forcing efficiency?

This seems like such a great stove! Great to see the tapered top that keeps
the right cross sectional area under the pot!

What do people think: Is a conical chimney an improvement over a
cylindrical one? Does the smaller opening near the top of the chimney force
flame together and lessen smoke and harmful emissions?

Great Stuff,

Dean Still

From english at adan.kingston.net Mon Aug 24 23:11:40 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:02 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808220307.XAA07719@adan.kingston.net>
Message-ID: <199808250321.XAA07048@adan.kingston.net>

Dear Norbert and all,

I have been looking at the data files of the test burns for
Masonry Heater, which were archived at
http://mha-net.org/msb/html/lop-arc.htm#Data

When looking at this data I feel it is justified to ignore the
predictable rise in CO emissions during the charcoal phase at the end
of the batch burn cycle. Regardless, I agree with Norbert,
there seems to be ample evidence of a lack of correlation between
carbon monoxide emissions and particulate matter emissions over a the
fairly wide range of the CO/CO2 ratios and excess air factors,
typical of these tests. Only in a few cases related to start up,
where emissions for CO and Particulates were very high, was there a
clear positive correlation between the two. The CO and CO2 levels
were similar to measurements I have taken during unbridled batch
burns in box stoves.

I should point out that in the majority of cases, the masonry heater
tests showed that their particulate matter emissions were lower than
the current best values for EPA approved wood stoves, on a grams per
kilograms basis. Bravo!

> My gut feeling is that the correlation simply isn't there, except
> perhaps for a few very controlled scenarios (advanced cooking stoves
> just might be one of them, however). Although I'm very far from
> being an expert, my browsing of the literature on pyrolysis etc.,
> tells me that wood combustion chemistry is extremely complicated,
> compared to fossil fuel combustion. There are so many interactions
> and possible chemical pathways that it makes the mind spin. From my
> observations with cordwood, there seem to be two main CO sources:
> fuel-rich, unmixed, cold conditions at startup, when volatiles
> predominate, and charcoal burning at the end.

For me, the question remains, is there an emissions correlation for
more "controlled" wood combustion operating at lower CO/CO2 ratios.
perhaps with less excess air? Can that added control be low tech?

Surely greater "control" is the only possible route to cleaner
combustion. The masonry heaters tests were conducted with some
control over fuel characteristics and arrangement. Air was limited
somewhat, and the design minimizes cold surfaces where flames would
quench. Correct me if I am wrong Norbert, but these masonry heaters
don't have features which attempt to "control" or improve upon the
random turbulence which occurs naturally in the flame path which
flows upward from the fuel.

It appears from the data in D-hk94c.xls that some operational
'control' resulted in a significant reduction of PM emissions
for the later runs 7 to 16, as compared with 1 to 6. ?

> For a masonry heater, really clean would be .001, but that would
> be over the whole burn cycle, including cold start and charcoal
> phase.

Please check this again, I think this is an error. The single point
best CO/CO2 that I found in the data was closer to .003, with the
average, during the 'stable' middle portion of the burn, being closer
to .01. A target standard for 'clean' combustion in steady state chip
burners, for example, would be .00125 or less. Seemingly small
decimal differences, being ratios, mean more than they may appear to.
These lower numbers represent conditions like higher
temperatures and better mixing which are necessary for the more
complete conversion of CO and presumably many of the compounds which
would ultimately end up as particulate emissions.

Some additional data would be helpful for this exploration. If some
of the best EPA stoves are operating with better CO/CO2 ratios
while achieving no better PM results, then I don't have a point. If
the 'clean' chip burners are no better on PM, then I don't have a
point. It could be that other factors are key.
There are a number of possibilities, perhaps none of them are
relevant to masonry heaters.

Given the nature of cooking stoves, cold start, small scale and
fuel variability, it wouldn't be hard to be a skeptic.

For now I shall remain a naivic. Alex

PS. There are folks on this list who could shed light on this topic.

From mheat at mha-net.org Tue Aug 25 06:27:24 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:03 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <Version.32.19980822052726.00f09490@mha-net.org>
Message-ID: <Version.32.19980825042713.00dd2780@mha-net.org>

At 11:19 PM 24/08/98 -0500, Alex English wrote:

>
>Surely greater "control" is the only possible route to cleaner
>combustion. The masonry heaters tests were conducted with some
>control over fuel characteristics and arrangement. Air was limited
>somewhat, and the design minimizes cold surfaces where flames would
>quench. Correct me if I am wrong Norbert, but these masonry heaters
>don't have features which attempt to "control" or improve upon the
>random turbulence which occurs naturally in the flame path which
>flows upward from the fuel.

Some may have features that are claimed to do this or that, but the
interesting thing is that none of it has survived the scrutiny of testing.
We are using a dead simple air supply - not because it is the best, (I'm
sure that it isn't, actually), but because nothing that we've tried so far
had much effect. The wood sizing and stacking effects far outweighed
anything we did with air configuration. As far as I can tell, the most
significant parameter is the kindling progression. One of our problems is
the fact that, to simulate real world conditions, we can only fire each
heater once a day. We were most interested in getting a good baseline, and
had to do many repeat runs to get a handle on what I would simply term
chaos. I read with interest Grant's appendix on factorial experiment
design, and am interested to learn what the applications might be with such
clearly non-linear systems.

As a side note, we were also testing fireplaces with airtight glass doors,
and did, literally, stumble upon a new air supply that made a dramatic
difference in PM emissions (compared to a conventional air supply),
although not so much with CO. It consists of a 1" dia tube on each
sidewall, aimed at the fire. With an airtight door, all of the chimney
draft is thus available at the air tubes to create velocity and hence
turbulence. The fire has a "blowtorch" effect, and stack temperatures get
into the 750 F range.

>It appears from the data in D-hk94c.xls that some operational
>'control' resulted in a significant reduction of PM emissions
>for the later runs 7 to 16, as compared with 1 to 6. ?
>

Yes. We were playing around with the air supply during this series.
Ironically, the improvement came from deleting any of the things that we
thought might work. In subsequent tests, we kept the air supply constant,
and were later able to extract some statistical effects by aggregating a
large number of tests. The best decision we made was to keep very detailed
fuelling records - we weighed each piece of fuel, measured its moisture,
length and cirumference (perimeter). We had a specific stacking order, and
numbered each piece in the stack. We laid the pieces out in order on the
floor and photographed them, then stacked them and photographed them again.
This only adds about 10 minutes of work per test.

When we looked at the data later, there was a clearly defined effect on PM
from fuel surface-to-volume ratio. Conventional masonry heater wisdom from
Europe had been to burn small wood, and burn it fast. We got better numbers
by burning large wood (to a point), and slowing the burn down a bit. This
may have to do with the fact that European masonry heaters were tradionally
room heaters, and had fuel loads of 5 to 10 kg. Rich North Americans of
course want to heat whole houses with them, so we've got the fuel loads
bumped up to 20 - 30 kg.

For the testing that we did here in Shawville 2 years ago, I got a digital
camera and we replaced the loading doors with a single piece of ceramic
glass and photographed the burns at 5 minute intervals for the first 30
minutes and at 10 minute intervals for the remaining 90 minutes (a number
of these sequences are posted on our website as animated gifs)

The most recent air supply that we were experimenting with is based on the
old one, which simply consists of a 1" x 14" slot at the front of the
firebox, at floor level. With the new air supply, we have a moving plate
that is lowered as the burn progresses, reducing the air and at the same
time creating more jetting. It seems to give about 2 to 3 % added overall
efficiency. I didn't spring for the $750 replacement CO cartridge on my
analyzer, and we don't have the Condar sampler here, so we didn't get any
emissions data from the '96 test series.

>> For a masonry heater, really clean would be .001, but that would
>> be over the whole burn cycle, including cold start and charcoal
>> phase.
>
>Please check this again, I think this is an error. The single point
>best CO/CO2 that I found in the data was closer to .003, with the
>average, during the 'stable' middle portion of the burn, being closer
>to .01. (snip)

Yes, you are right. I should have said .01 - its been about 3 years since
we actually did CO testing. That's my excuse for slipping the decimal
point, and I'm sticking to it :-)

Best..........Norbert

From gottlieb at cbl.umces.edu Tue Aug 25 11:32:05 1998
From: gottlieb at cbl.umces.edu (Sara J. Gottlieb)
Date: Tue Aug 31 21:36:03 2004
Subject: introduction and pellet stove question
Message-ID: <Pine.GSO.3.96.980825113646.22606A-100000@cbl.umces.edu>

Hi,

I am a new member of this list. The reason I subscribed is to get more
information about pellet stoves. My husband and I recently moved to the
Sandia Mountains outside of Albuquerque, NM. Our house has in-floor
radiant heat, powered by butane. Our gas bill last winter was
astronomical, and I'd like to do something about it. The house was meant
to have a wood or pellet stove (we have the chimney in the roof!) but the
previous owners never put it in.

We are now comparison-shopping for such stoves, and have come down to a
Reliant model with a battery backup (we lose power frequently enough that
we worry about heat) and a Jamestown model without battery backup. One
salesperson told us we would spend $175 for a ton of pellets that would
last the whole winter, and another told us it would cost $275 for the
whole winter. Considering that the pellet stoves are a pretty big
investment to start up, I'd like to reap the savings as quickly as
possible.

If any of you have experience using pellet stoves for heat, please contact
me to discuss. I'd appreciate it!

Thanks,
Sara Gottlieb

--------------------------------------------------------------------------
Sara J. Gottlieb gottlieb@cbl.umces.edu

WWW:http://cbl.umces.edu/~gottlieb

"To be yourself, in a world that tries, night and day, to make you just
like everybody else - is to fight the greatest battle there ever is to
fight, and never stop fighting."
-e.e. cummings

From fbouvet at icrc.org Wed Aug 26 07:12:04 1998
From: fbouvet at icrc.org (Franck Bouvet)
Date: Tue Aug 31 21:36:03 2004
Subject: improved stoves for public kitchens
Message-ID: <4125666C.00431DA3.00@gvalnmta.icrc.org>

Franck Bouvet@ICRC_GVA
08/26/98 01:14 PM

Dear all ,

The International Committee of the Red Cross is involved in the improvement
of the living conditions in the prisons all around the world. The ICRC
Environmental Health Unit tries to improve the cooking technics by
installing mainly Bellerive 200, 100 and 50 liters SMP stoves. These stoves
are fuelwood based and the saving rate of wood is quiet good comparatively
to open fire cooking.

We would like to test Kerosene or/and Petrol Stoves for both purposes :
community kitchens in the prisons (big capacity stoves necessary), and
emergency feeding programs where finding wood is a problem (like in South
Sudan now).

I would like to know :

1. Concerning fuelwood stoves : is there any other stoves (except the one
developped by REDI) useful for high population community cooking (over than
1000 persons, 3 meals a day) ? Have these stoves been tested and in which
condidtions ?

2. Concerning kerosen / petrol stoves : is there any stove currently
existing on the market ? Have they been tested ? What are their efficiency
and their consumption ?

3. Where can I get relevant information on these two subjects ?

I would very much appreciate any kind of help

Kind regards.

Franck Bouvet
ICRC
OP SAN UNIT
12 av. de la paix
CH 1202 Geneva

--------------------------------------------------------
* Personal e-mail - not an official ICRC communication *
--------------------------------------------------------

From kammen at princeton.edu Wed Aug 26 11:20:14 1998
From: kammen at princeton.edu (Daniel Kammen)
Date: Tue Aug 31 21:36:03 2004
Subject: request for information on larger stoves for public kitchens
Message-ID: <l03110712b209a21f9cbf@[128.112.47.34]>

I recieved the following request from the Red Cross, and thought that the
people on this list would
have a range of stoves to suggest for testing and application here. please
be sure to provide
details on where to obtain information or to order any stove you suggest --
from the message
you can see that they would like to evaluate or to begin testing directly.

if anyone has suggestions, could they either post them or email them to me
and i'll forward the
bunch on to the Red Cross.

thanks,

dan

***********

I would like to know :

2. Concerning kerosen / petrol stoves : is there any stove currently
existing on the market ? Have they been tested ? What are their efficiency
and their consumption ?

_________________________________________________________________

Daniel M. Kammen
Assistant Professor of Public and International Affairs
Chair, Science, Technology & Environmental Policy (STEP) Program
201 Five Ivy Lane
Woodrow Wilson School of Public and International Affairs
Princeton University
Princeton, NJ 08544-1013

Tel: 609-258-2758 Fax: 609-258-6082, or 2394
Email: kammen@princeton.edu
WWW: http://www.wws.princeton.edu/~kammen/
Secretary Jackie Schatz: Tel: 609-258-4821
Email: jackie@wws.princeton.edu
__________________________________________________________________

From john at gulland.ca Wed Aug 26 11:42:11 1998
From: john at gulland.ca (John Gulland)
Date: Tue Aug 31 21:36:03 2004
Subject: introduction and pellet stove question
In-Reply-To: <Pine.GSO.3.96.980825113646.22606A-100000@cbl.umces.edu>
Message-ID: <000d01bdd109$761c02e0$2236f8ce@jgulland.igs.net>

Sara J. Gottlieb wrote:
>
> If any of you have experience using pellet stoves for heat, please contact
> me to discuss. I'd appreciate it!
>

HearthNet is a commercial site better suited to homeowner questions about
products and their performance. The home page is here: http://hearth.com/
You might try the fuel cost calculator on HearthNet found here:
http://chi.hearth.com/addcalc.html And you can also post a question to the
webmaster. He is a good source of reliable advice.

Regards,
John
This is for business: http://www.gulland.ca/
This is for pleasure: http://www.wood-heat.com/

From larcon at sni.net Wed Aug 26 12:16:19 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:03 2004
Subject: Alex Mulet-Hernandis - New member introduction -
Message-ID: <v01540b01b209b5df1746@[204.133.28.24]>

Stovers - In response to my usual request for new list members to provide
an introduction when ready, Alex has replied:

>Allright Mr Larson,
>My name is Alex Mulet, and I am a multidisciplinar Engenier. Nowdays I
>am working on increasing eficiency on energy use, specially on a
>medium scale implementations, and therefore, most interested on items
>such as the discussed in your list.
>I expect to participate the best I am able to.
>By the way I live in Europe, by the Mediterranean, with the
>implications it carries on energy use.
>Best Regards
>Alex

<alexmulet@yahoo.com>

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From larcon at sni.net Wed Aug 26 12:16:31 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:03 2004
Subject: improved stoves for public kitchens
Message-ID: <v01540b03b209cad503db@[204.133.28.24]>

Franck: you asked these questions:

>1. Concerning fuelwood stoves : is there any other stoves (except the one
>developped by REDI) useful for high population community cooking (over than
>1000 persons, 3 meals a day) ? Have these stoves been tested and in which
>condidtions ?
>
I hope that Elsen Karstad or someone else in Nairobi will supply
the names, addresses, and phone numbers of the several developers of large
institutional wood stoves that we saw in June. Nairobi should be one of
the best places to explore this topic - but I am sure there are others that
our list can supply products or ideas also.

>2. Concerning kerosen / petrol stoves : is there any stove currently
>existing on the market ? Have they been tested ? What are their efficiency
>and their consumption ?

I would guess that many of the Nairobi stoves could be readily
converted to alternative, maybe even mixed, fuel use. Again I believe that
Elsen can help find a way to get to those builders, some (but not all) of
whom are on the list.

I also strongly urge your consideration of a wonderful solar
institutional cook stove that I saw operating in Khartoum. Remarkably,
this is a large tracking concentrator which can operate every day at a 15
degree/hour constant (falling weight clock) tracking speed. Many solar
experts will tell you this is impossible - but it is done by weekly changes
in the shape of the reflector surface. The developer is Dr. Salih Hamadto
- a very bright person. I hope that list member Dr. El Fadil (a Sudanese
now in Germany) will chime in on how to reach someone in Khartoum who can
tell Franck how to reach Dr. Hamadto. The basic idea came from someone in
Switzerland, but Dr. Salih made it practical. I think there are maybe ten
of these in operation.

>
>3. Where can I get relevant information on these two subjects ?

I hope others will chime in to help on these two.

I would also like to offer that many of us on the list believe that
one can meet this type of cooking need most cheaply by simultaneously
making charcoal. Franck - please look back in our archives (www.crest.org)
and look up our photo archives with Alex English at
http://www.ikweb.com/enuff/public_html/Stoves.html.

There will need to be some development effort, but it should not be
difficult. I believe we have already demonstrated that we can do this at
the required power and energy levels needed for institutional cooking. In
large refugee camps (and prisons) there should be adequate metal working
and construction skills to assist greatly in that development. Many on
this list will help supply the ideas once we better understand your
particular locations you have in mind.

You may not be able to implement this where there absolutely no
trees, but Southern Sudan should not be one of those places, given its
abundant rainfall. There may be a need for a year or so of growth
following planting, but an immediate reforestation effort should be
something people are doing anyway. When I say a year, I am thinking of
rootfuel crops. I am hopeful that the Red Cross will not turn to expensive
non-renewable fuels in the circumstances that you are describing.

Best of luck in your efforts.

>
>I would very much appreciate any kind of help
>
>Kind regards.
>
>Franck Bouvet
>ICRC
>OP SAN UNIT
>12 av. de la paix
>CH 1202 Geneva
>
>
>
>--------------------------------------------------------
>* Personal e-mail - not an official ICRC communication *
>--------------------------------------------------------
>

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From cetep at reacciun.ve Wed Aug 26 16:48:15 1998
From: cetep at reacciun.ve (CETEP)
Date: Tue Aug 31 21:36:03 2004
Subject: Stovers Conference
Message-ID: <35E46928.32E25A46@reacciun.ve>

Rogerio Miranda
Ron Larson
Estimados amigos:
escribi una pequeña nota a la señora Priyadarshini Karve mencionandole
nuestro interes en la conferencia de la India del año 2000. Le
mencionaba yo a ella que preferiria establecer la relacion en español.
Su contesta fue muy amable y rapida, pero lo del idioma no se puede
resolver. Asi que me sugirio que la informacion solicitada por ellos la
envie a ustedes en español y probablemente ustedes podran ayudar en su
traduccion.
Desearia que me confirmen este asunto para hacerles llegar dicha
informacion. Al mismo tiempo les consulto si el idioma sera una
limitacion para participar en la conferencia o si se resolveria a traves
de la traduccion simultanea.
Esperando su contesta les desea el mayor de los exitos y les agradece
por apoyar este tipo de iniciativas en favor de la poblacion rural del
mundo.
Nacho Alzuru

From larcon at sni.net Thu Aug 27 15:29:55 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:03 2004
Subject: Tim Janosik request on small coffee heater
Message-ID: <v01540b00b20a9a00594e@[204.133.28.32]>

Stovers: The following in today from Dr. Yury (who I thank), on issues
related to the construction and operation of a samovar. I am interested in
the samovar (and what is probably a similar device - the Kelly Kettle)
primarily because the design seems so perfect for high efficiency. The idea
of a water jacket seems also quite well suited to charcoal-making stoves -
whenever hot (and healthier) water would be another useful co-product.

I had not expected that you (and now I'm sure many other Russians)
would be so fond of this device. I agree with you on the samovar's beauty
(and because of that I bought one of my own several years ago).

Unfortunately I am like many others and don't take the time to use
it. But perhaps some of its design principles have a place in other
countries where cooking must be done with wood.

Two more questions:

1. Do you think it might be possible to do both water heating and
cooking effectively in one design?

2. Are your aware of any efficiency measurements on samovars?

Thanks again. From here on is Dr. Yury's response to my earlier message:

Dear Ron,
Samovar represents two cylinders inserted one in another. The outside
cylinder in 5... 6 times more internal. The bottom of the external cylinder
is soldered both to it and to internal on perimeter. A cover have an
aperture in the middle for the internal cylinder and board on perimeter.
Usually it has two handles for removal of a cover. The central cylinder
serves by pipe, and its bottom part leaves below bottom and comes to an
end by the small chamber for charcoal or fine wood. On perimeter of this
chamber there are apertures for receipt of air and ignition of fuel, which
can be closed by the mobile outside small cylinder partially or completely
for adjustment of burning. From above on the internal cylinder the
additional pipe for improvement draught is put on. Is much variants in the
form of a cone, sphere and more complex. There are many additional devices
facilitating usage and regulation. S happens is very beautiful and
decorates a table. Modern Russian prefer unfortunately electrical
imitation. Culture ancient to drink of tea is forgotten, and it was the
special ceremony, absolutely another than at Japanese. It was feature of
life of the lowest classes, but also the aristocrats used it, when lived in
the rural houses. If you when will arrive to St. Petersburg, and I it want
very much , I shall carry you in the rural house and we shall drink tea
from mine samovar.

----------
> Ronal W. Larson <larcon@sni.net>
> stoves@crest.org
> janosik@spectrumevents.com
> re: Tim Janosik request on small coffee heater
> 08.16.1998
.................>
> 2. The concept of an interior fuel chamber and chimney is
inherent
> in the Russian Samovar that has been mentioned several times on this
list.
> I would appreciate hearing from Dr. Yury or others of any studies of the
> efficiency of the samovar. I would guess that Samovars may have been used
> for centuries - and that their efficiency may be very high.

This very simple device. It is easy for making. It is economic, a smoke the
pipe passes inside and warmly is not lost. But it is necessary to be able
to light and to add fuel.
Yury

> 3. Can anyone can tell me how the bottom of a samovar (or the
> Kelly Kettle or the Australian heater or any unit with an inner
> combustion/pyrolysis zone and an outer water jacket) is sealed? Can this
> sealing be done by traditional metal workers in remote villages?
>
> Regards Ron
...............

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From fbouvet at icrc.org Fri Aug 28 04:58:51 1998
From: fbouvet at icrc.org (Franck Bouvet)
Date: Tue Aug 31 21:36:03 2004
Subject: report on the kerosene presurized stoves tested at Eindhoven by a student from ecuador
Message-ID: <4125666E.00369DF3.00@gvalnmta.icrc.org>

Franck Bouvet@ICRC_GVA
08/28/98 11:01 AM

Dear Etienne, Dear All

If you or anyone would have a copy of this report mentioned in the msg01551
from Etienne toElisabeth, I would be very interested in having a copy of
it.

Thks

Franck Bouvet
ICRC
12 av. de la paix
1202 Geneva
Switzerland

--------------------------------------------------------
* Personal e-mail - not an official ICRC communication *
--------------------------------------------------------

From REEDTB at compuserve.com Fri Aug 28 19:32:46 1998
From: REEDTB at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:36:03 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
Message-ID: <199808281942_MC2-57B3-966C@compuserve.com>

Dear Alex et al:

We all share concerns in the measurement of emissions, particularly from
cooking stoves which are likely to be used indoors with the cook very close
to whatever escapes combustion.

A MAJOR reason for our interest here in WOOD-GAS stoves (as opposed to WOOD
STOVES) is that gasification permits (but does not mandate) clean
combustion by control of air fuel ratios during combustion of volatiles and
charcoal.

It is important to realize that the gases generated in flaming combustion
are very different from those arising from the charcoal, though both
contain high levels of CO.

I have a (Morningstar?) simple CO meter that I have been using to monitor
my current TURBO wood-gas stove. The stove provides adequate (but not too
much) air for secondary combustion of the gas in a well insulated chamber,
and I don't measure any CO, though I would like a better tester.

I recently placed the CO meter directly over my stove after I had
"extinguished" the stove by placing a ceramic lid over the flame holder. I
was surprised to see on checking 4 hours later that the stove was still
hot, presumably due to a small leak of primary air. 8 hours later, at 2 AM
my wife shook me awake to fix the alarm on the meter that emitted a
piercing shriek and registerd 150 ppm CO (our in my lab). Wow! A
thermocouple in the charcoal bed registered only 150 C.

>From this I learned how difficult it is to extinguish the charcoal and how
little air it takes to continue CO generation, even at very low
temperature. Frankly I am puzzled, because, while charcoal burns primarily
to CO
above 700C, equilibrium calculations show that it makes primarily CO2 at
lower temperatures, and I should have thought very little at 150C. So,
I'll run some more tests and calculations. Meanwhile, BE CAREFUL about
"nascent" charcoal (freshly formed and very pyrophoric!).

Your netpal, TOM
REED

It is incredibly difficult to

Dear Norbert and all,

It appears from the data in D-hk94c.xls that some operational
'control' resulted in a significant reduction of PM emissions
for the later runs 7 to 16, as compared with 1 to 6. ?

> For a masonry heater, really clean would be .001, but that would
> be over the whole burn cycle, including cold start and charcoal
> phase.

Given the nature of cooking stoves, cold start, small scale and
fuel variability, it wouldn't be hard to be a skeptic.

For now I shall remain a naivic. Alex

PS. There are folks on this list who could shed light on this topic.
Stoves List SPONSORS and ARCHIVES:
http://solstice.crest.org/renewables/stoves-list-archive/
Stoves Webpage
http://www.ikweb.com/enuff/public_html/Stoves.html
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http://www.ikweb.com/enuff/public_html/Chamber.htm

From REEDTB at compuserve.com Fri Aug 28 19:32:54 1998
From: REEDTB at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:36:03 2004
Subject: GAS-L: tar analysis
Message-ID: <199808281942_MC2-57B3-966D@compuserve.com>

Dear Hans Jurgen Koele et al:

>What methods are common to analysis tar?

Try http://btg.ct.utwente.nl/Projects/558

Hans Jurgen Koele.
>

HJK asks about the measurement of "tar".

The measurement and reporting of "tar" is in a state of flux these days, so
it is hard to give a solid answer..

1) The pejorative word "tar" has many different compositions, depending on
the method of gasification

2) The European Energy Commision is spending a great deal of time and
money trying to define "tars" and specify measurement methods

3) Tar may actually be beneficial in heating applications where it adds to
fuel value of producer gas - possibly making a 5 MJ/m3 gas actually 10 or
20 MJ/m3

4) Tars should not be confused with particulates, typically char-ash or
soot

I heard the other day that the EEC had reached a tentative agreement that
"tar" was that fraction of condensibles boiling above 80 C. (This has the
advantage of excluding benzene from being called tar.) This means that
diesel fuel is a "tar". Also water. I hope this isn't a final decree.

>From my viewpoint, only condensible materials that cause a problem for a
PARTICULAR application should be called a TAR for that application. So,
creosotes that stick to engine parts at 100C would be a tar for engines,
but would be burned in turbines, so would not be a tar there.

A monograph on tar is being prepared by folks at NREL. I hope they get
this all sorted out. Meanwhile, Agua Das and I are re-editing his 1988
CONTAMINENT TESTING FOR GASIFIER ENGINE SYSTEMS at the BEF Press. This
specifies methods for measuring "tar" for operation of IC engines.

COMMENTS???

Yours truly, TOM REED

~~~~~

CONTAMINANT TESTING FOR GASIFIER ENGINE SYSTEMS - A. Das Long engine life
and reliable operation requires a gas with less than 10 mg of tar and
particulates per cubic meter (10 ppm). The simplified test methods
described here are adapted from standard ASTM and EPA test procedures for
sampling and analyzing char, tar and ash in the gas.
32pp.................................. ..$15.00

>What methods are common to analysis tar?

Try http://btg.ct.utwente.nl/Projects/558

Hans Jurgen Koele.

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From REEDTB at compuserve.com Fri Aug 28 19:33:02 1998
From: REEDTB at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:36:03 2004
Subject: introduction and pellet stove question
Message-ID: <199808281942_MC2-57B3-9670@compuserve.com>

Dear Sara and STOVES:

Our group, STOVES, here at CREST, should more properly be called "COOKING
STOVES FOR DEVELOPING COUNTRIES" - at least that is how it started.
However, we have also become a main source of information on charcoal
making.

Your question about pellet stoves doesn't fit either category, but I hope
you will get some answers to your question here.

I have long believed that DENSIFIED BIOMASS (pellets, cubes, logs, ....)
are an important aspect of a world where biomass is a major energy source.
Typical biomass has a density from 0.05 (straw) to 1 (coconut shell) g/cm3,
while any good pellet/cube/log has a density > 1.

Densification of thousands of kinds of biomass waste can create a uniform
fuel, easily shipped, stored and used - a FUNGIBLE BIOMASS FUEL. There are
many problems between this ideal and the present, but things are moving
nicely. If all biomass occured in DENSIFIED form I am sure it would be a
major energy source already.

So, the same pellets that will fuel Sara's Heating Stove can also be an
excellent fuel for cooking stoves for developing countries. I am currently
testing a stove: Cooking time with wood chips - 12 minutes; Cookig time
with peanut shell pellets - 1 hour.

Pellet Heating Stoves are a major invention of the last decade. They burn
so clean they can be burned indoors without a flue - for short periods.

Unfortunately, I don't have any information about the relative merits of
various commercial brands, but I hope such info will show up here. Maybe
there is a web page.

Your STOVEpal, TOM REED
Stoves List SPONSORS and ARCHIVES:
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Stoves Webpage
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For information about CHAMBERS STOVES
http://www.ikweb.com/enuff/public_html/Chamber.htm

From larcon at sni.net Fri Aug 28 22:59:58 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:03 2004
Subject: Peter Verhaart on "Emission targets for Wood Fueled Cooking Stove"
Message-ID: <v01540b01b20d1ad4d71e@[204.133.28.32]>

Stovers - Piet's message again got bumped to me because he has two e-mail
addresses (Piet-please remind me if I should have made a change that I
didn't - Ron)

Dear Alex, Norbert and other Stovers,

On 24/8 you mentioned an increase in CO emissions during charcoal
burning.
We observed a similar rise in the Downdraft burner. This occurred after all
the wood had turned into charcoal and no more fresh wood was fed. At this
point temperature would also drop but not very much, and there is plenty
oxygen around. The only possible explanation we could think of was absence
of water vapour (is supposed to catalyse the CO - CO2 reaction) after
volatiles have burned up.
As we have often mentioned, the DD burner burned extermely clean, no
smell. The venom resided in the tail.

Norbert (I think) mentioned fitting two 1" dia tubes on eacht sidewall of a
fireplace with airtight glass doors, which improved emissions.
In May 1995, during a trip to Tasmania, we saw many wood burning space
heaters at work. One that particularly impressed me had an airtight glass
door and through a slit at the front, just above the grate a jet of air was
directed at the fuel. The flames etc turned away from the fuel to leave
the combustion space at the top front of the heater to circulate through a
heat exchanging circuit before leaving through the chimney.
The clean combustion was achieved by guiding the hot combustion products
away from the bulk of the wood. A similar result is achieved by top-down
burning. Both methods prevent (to some extent) hot gases coming into
contact with fuel outside the actual combustion zone. I think that is the
way to go.

Best regards,

Piet
Peter Verhaart, 6 McDonald St. Gracemere Q 4702 Australia
Phone: +61 7 4933 1761; fax: +61 7 4933 1761 or
+61 7 4933 2112 (when computer is on); mobile: 0412 457239
E-mail p.verhaart@cqu.edu.au

From mheat at mha-net.org Sat Aug 29 10:16:34 1998
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:36:03 2004
Subject: Peter Verhaart on "Emission targets for Wood Fueled Cooking Stove"
In-Reply-To: <v01540b01b20d1ad4d71e@[204.133.28.32]>
Message-ID: <Version.32.19980829082347.00f26340@mha-net.org>

At 09:11 PM 28/08/98 -0600, Peter Verhaart wrote:

(snip) One that particularly impressed me had an airtight glass
>door and through a slit at the front, just above the grate a jet of air was
>directed at the fuel. The flames etc turned away from the fuel to leave
>the combustion space at the top front of the heater to circulate through a
>heat exchanging circuit before leaving through the chimney.
>The clean combustion was achieved by guiding the hot combustion products
>away from the bulk of the wood. A similar result is achieved by top-down
>burning. Both methods prevent (to some extent) hot gases coming into
>contact with fuel outside the actual combustion zone. I think that is the
>way to go.
>
Hello Piet and other stovers:

Very interesting that you should say this. When we did the masonry heater
testing, the absolutely cleanest burns where achieved using our standard
air supply, which is similar to the one you describe, and a kindling
progression where a fast start at the front bottom of the fuel pile (aided
by the immediately adjacent air slot) climbed up the front of the pile, and
within 60 seconds resulted in a ball of flame above the pile, while only
the front of the pile was yet burning.

The result was perhaps 50% lower PM emissions that a standard clean burn,
due probably to the particular kindling progression, with a "sensitive
dependence on initial conditions". I believe that fuel pile geometry is the
most significant variable in this instance (cold start emissions from a 30
kg cordwood fuel pile), and that time-lapse photographic data and detailed
fuelling data are important.

Best........Norbert

From btremeer at dds.nl Sun Aug 30 09:09:43 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:03 2004
Subject: CO formation, was RE: Tom Reed on Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808281942_MC2-57B3-966C@compuserve.com>
Message-ID: <000101bdd418$a4a321e0$2f0deed4@blackthorn>

Dear Tom

As far as I understand it CO2 is formed preferentially at lower temperatures
(below 400C) only in the presence of sufficient oxygen. When inlet air is
restricted, temperatures are too low, or where there is insufficient oxygen
for complete combustion smouldering occurs. The lower temperatures of the
smouldering stage results in a lower oxygen supply from diffusion into the
fuel bed - gases in this phase which leave the fuel bed are not oxidised
further, and relatively high levels of CO are produced. I'd thus expect high
CO levels at both low and high temperatures, and low levels in between.

I'm by no means an authority on this very complicated subject, but I think
this may explain your 2am wake up...

Regards
Grant

-------------------
Grant Ballard-Tremeer
btremeer@dds.nl; http://www.energy.demon.nl
-------------------

-----Original Message-----
From: owner-stoves@crest.org [mailto:owner-stoves@crest.org] On Behalf Of
Tom Reed
Sent: 29 August 1998 01:42
To: INTERNET:english@adan.kingston.net
Cc: GASIFICATION; STOVES
Subject: RE: Emissions Target for Wood Fueled Cooking Stove

Dear Alex et al:

We all share concerns in the measurement of emissions, particularly from
cooking stoves which are likely to be used indoors with the cook very close
to whatever escapes combustion.

It is important to realize that the gases generated in flaming combustion
are very different from those arising from the charcoal, though both
contain high levels of CO.

Your netpal, TOM
REED

It is incredibly difficult to

Dear Norbert and all,

I have been looking at the data files of the test burns for
Masonry Heater, which were archived at
http://mha-net.org/msb/html/lop-arc.htm#Data

When looking at this data I feel it is justified to ignore the
predictable rise in CO emissions during the charcoal phase at the end
of the batch burn cycle. Regardless, I agree with Norbert,
there seems to be ample evidence of a lack of correlation between
carbon monoxide emissions and particulate matter emissions over a the
fairly wide range of the CO/CO2 ratios and excess air factors,
typical of these tests. Only in a few cases related to start up,
where emissions for CO and Particulates were very high, was there a
clear positive correlation between the two. The CO and CO2 levels
were similar to measurements I have taken during unbridled batch
burns in box stoves.

It appears from the data in D-hk94c.xls that some operational
'control' resulted in a significant reduction of PM emissions
for the later runs 7 to 16, as compared with 1 to 6. ?

> For a masonry heater, really clean would be .001, but that would
> be over the whole burn cycle, including cold start and charcoal
> phase.

Given the nature of cooking stoves, cold start, small scale and
fuel variability, it wouldn't be hard to be a skeptic.

For now I shall remain a naivic. Alex

From btremeer at dds.nl Sun Aug 30 09:09:48 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:03 2004
Subject: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808250321.XAA07048@adan.kingston.net>
Message-ID: <000201bdd418$a731bc00$2f0deed4@blackthorn>

Dear Norbert, Alex and all

>> My gut feeling is that the correlation simply isn't there, except
>> perhaps for a few very controlled scenarios (advanced cooking stoves
>> just might be one of them, however). Although I'm very far from
>> being an expert, my browsing of the literature on pyrolysis etc.,
>> tells me that wood combustion chemistry is extremely complicated,
>> compared to fossil fuel combustion. There are so many interactions
>> and possible chemical pathways that it makes the mind spin. From my
>> observations with cordwood, there seem to be two main CO sources:
>> fuel-rich, unmixed, cold conditions at startup, when volatiles
>> predominate, and charcoal burning at the end.

>For me, the question remains, is there an emissions correlation for
>more "controlled" wood combustion operating at lower CO/CO2 ratios.
>perhaps with less excess air? Can that added control be low tech?

I considered the correlation of CO and particulates for cooking stoves in
some detail in my thesis in order to find out if measuring CO was a
sufficient indicator of particulates. For some stoves (typically enclosed
with restricted air inlet) there was a fairly good correlation (correlation
co-efficient roughly 0.8), for others (typically open) almost no correlation
could be found (correlation 0.02). The emissions of the enclosed stoves are
dominated by the fuel ignition peaks (bear in mind that the whole test is
over in roughly 40 minutes and two charges of fuel were used during this
time) whereas the open fires do not have the same start-up behaviour (new
wood starts to burn throughout the test as the fire is tended). Stove
geometry therefore seems to have a significant impact on correlation. My
feeling is that the emission pattern of the enclosed stoves was dominated by
large variations in burn rate whereas for open fires, that have steadier
burn rates, the combustion characteristics dominate. I imagine Norbert's
masonry heaters have a fairly steady burn rate soon after ignition and I'd
thus expect to find a poor CO/particulate correlation.

My overall conclusion was the same as Norbert's: that the correlation just
isn't there and both CO and particulates need to be measured. Unfortunately.
I did however find that, on a total emission per test basis, it was roughly
valid to say that high total CO indicated high particulates. This conclusion
is not based on comparisons within a test on one stove, but comparisons
between stoves.

Details of my comparisons can be found in my thesis at
http://www.energy.demon.nl/PhDch5.htm.

All the best
Grant

-------------------
Grant Ballard-Tremeer
btremeer@dds.nl; http://www.energy.demon.nl
-------------------

From btremeer at dds.nl Sun Aug 30 09:09:47 1998
From: btremeer at dds.nl (Grant Ballard-Tremeer)
Date: Tue Aug 31 21:36:03 2004
Subject: Opacity measurements RE: Emissions Target for Wood Fueled Cooking Stove
In-Reply-To: <199808211118.HAA10783@tor-smtp2.netcom.ca>
Message-ID: <000301bdd418$a8923660$2f0deed4@blackthorn>

Dear Norbert and Alex

You will probably have seen from my thesis (chapter 2) that my light
obscuration smoke meters were based on a British Standard for smoke density
indicators. In the standard (BS 2811: 1969) it is claimed that there is a
valid linear correlation (better than 97%) between the optical density and
mass concentration, and light obscuration equipment can therefore be
calibrated in terms of mass concentration. I did not have access to
resources to be able to assess the validity of this claim, beyond verifying
the respirable size range and 11 particulate samples to create a rough
calibration curve.

I will have a look round for some other particulate measurements from small
cooking stoves... I unfortunately don't have any data available with which
to compare my measurements, with the exception of a Food and Agriculture
Organisation report which mentions a suspended particulate concentration of
1.3 mg/m3 from an improved stove. Unfortunately, without information about
dilution levels I can't relate this to my own work. Perhaps someone else on
the list can shed some light on the subject? In the light of Norbert's
figures for masonry heaters perhaps my figures are much too low... I don't
know what the reason for that could be.

Regards,
Grant

-------------------
Grant Ballard-Tremeer
btremeer@dds.nl; http://www.energy.demon.nl
-------------------

From fbouvet at icrc.org Mon Aug 31 03:39:23 1998
From: fbouvet at icrc.org (Franck Bouvet)
Date: Tue Aug 31 21:36:03 2004
Subject: BOUNCE stoves@crest.org: Message too long (>40000 chars)
Message-ID: <41256671.002DBBD5.00@gvalnmta.icrc.org>

I just wanted to transmit a bibliography which could be helpful for all of
us.

If you contact Mrs Silvia N'Diaye, at SKAT, you can get it

email adress : Silvia.ndiaye@skat.ch

Rgds

Franck

From K.K.Prasad at phys.tue.nl Mon Aug 31 08:20:44 1998
From: K.K.Prasad at phys.tue.nl (K. K. Prasad)
Date: Tue Aug 31 21:36:03 2004
Subject: (Fwd) RE: Emissions Target for Wood Fueled Cooking Stove
Message-ID: <199808311231.OAA18084@silicon.tue.nl>

------- Forwarded Message Follows -------
From: Self <Single-user mode>
To: "Grant Ballard-Tremeer" <btremeer@dds.nl>
Subject: RE: Emissions Target for Wood Fueled Cooking Stove
Reply-to: K. K. Prasad@phys.tue.nl
Date: Mon, 31 Aug 1998 13:27:43

Dear Stovers

Here is a short comment on Grant's comments on emissions target from
cookstoves.

> From: "Grant Ballard-Tremeer" <btremeer@dds.nl>
> To: <stoves@crest.org>
> Subject: RE: Emissions Target for Wood Fueled Cooking Stove
> Date: Thu, 20 Aug 1998 00:17:04 +0200

> Dear all
>
> Yes. The main problem I think is that power is frequently controlled by
> varying primary and secondary air inlets rather than fuel feed rate (as is
> the practice in my gas stove).
>
> >Comments everyone?
> Ditto
>
> Best wishes
> Grant
>
>
>I agree with Grant. In order to change the power output it is
necessary to control the fuel feed rate. This is easily said than
done. In our lab we have tried to do experiments with different
charge sizes - that means adding a given quantity of fuel at fixed
intervals. To make things a little clearer power output in this type
of operation at least theoretically can be varied either by varying
the quantity of wood charged holding the time interval between
charges constant or varying the time interval holding the charge size
constant. Per definition both modes of operation should produce the
same result. Unfortunately real life produces a much different result.

The following is a brief description of some experiments we carried
out on a down-draft burner. We varied the charge size as well as
charging interval but held the ratio constant thus giving a constant
theoretical rate of charging. In the experiments we were able to
monitor the weight loss at intervals of the order of 10 seconds. With
the aid of this we were able to construct a graph showing the
"instantaneous" mass loss rate as a function of time. We used
120g/240s, 180g/360s, 240g/480s. In these experiments there was no
provision for air control and there was no secondary air either. The
mass-loss rate curve is almost bell-shaped with a flat top
representing the maximum mass-loss rate ( for a first approximation
maximum power). For the lowest charge size used the flat top lasted
about a minute and a half and for the highest charge it was just
under a minute corresponding to about 0.68g/s and o.92g/s. But the CO
content varied more dramatically - for the lowest charge size it was
about 0.2% while for the largest charge it was over 4%! What is more
this maximum lasted for a little over 2 minutes ( more than 25% of
the charge interval). What is more during this period the oxygen in
the flue gases was ZERO!!!

We have more experiments to show the difficulty of operating a
woodburning device at large charge sizes. In general larger the
charge size, poorer the quality of combustion. Of course secondary
air does help. We have some results demonstrating this.

One caveat, I would like to add. We have to do many more experiments
to assert the quantitative reliability of these results. However I
have little doubt about the qualitative correctness of the results we
have.

Should anybody be interested I can (snail)mail the relevant papers
that give more details and more results.

Prasad

From kchishol at fox.nstn.ca Mon Aug 31 14:05:09 1998
From: kchishol at fox.nstn.ca (Kevin Chisholm)
Date: Tue Aug 31 21:36:03 2004
Subject: Elementary Wood Combustion
In-Reply-To: <199808311231.OAA18084@silicon.tue.nl>
Message-ID: <E0zDYUF-0004LO-00@mail1.halifax.istar.net>

There are lots of extremely competent ppl on this list, who know
far more about the wonders of wood combustion than I do, and my
apologies to them if I am "teaching my Grandmother how to suck eggs."
However, there may be some newer students to the fine art who will
find the following to be helpful.

Energy Content:

Dry hardwoods with no resins has about 8,500 BTU/pound, while
resinous woods, like pitch pine, run as high as about 10,000 BTU/lb.

Air Requirements:

With perfect combustion, 1 cubic foot of air is required to release
about 105 BTU. Allowing for say 20% excess air means that 1 cubic
foot of air will liberate about 85 BTU Thus, 1 pound of wood burned
per hour requires 100 cubic feet of air per hour for efficient
combustion.

Primary and Secondary Air:

Any air contacting the fuel will promote gasification of the wood,
and the production of a very high percentage of combustibles and CO
in the stack gas. This is Primary Air. Secondary Air is air
introduced in a manner that it contacts the products of gasification
only, and burns it to completion.So-called "secondary air" that has
an opportunity to contact the fuel is really "more primary air" and
will result in low efficiency of combustion.

Heat Release:

Assuming only carbon is present, the reaction C===>CO liberates about
4,000 BTU/Lb Carbon, and the reaction CO====>CO2 liberates about
10,000 BTU/Lb. It is very important NOT to lose heat from primary
combustion, otherwise there is a "cold fire" which may not permit
ignition of the combustibles. The stove should be designed with a
relatively insulated "firebox" where the primary combustion occurs,
and the heat should be extracted only in the zone where secondary
combustion is designed to occur.

Particulates:

There are basically two kinds of particulates: Ash, which is a result
of turbulence and carry-over, and insufficient settlement space, and
Soots, as a result of poor combustion, and the carry-over of tars and
incompleted combustion. Soots can result from premature extraction of
heat from the primary combustion zone, cold combustion, and either
too little secondary air, OR too much secondary air, which also leads
to a "cold combustion" condition.

Hope this is helpful. :-)

Kevin Chisholm
Stoves List SPONSORS and ARCHIVES:
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From larcon at sni.net Mon Aug 31 21:26:34 1998
From: larcon at sni.net (Ronal W. Larson)
Date: Tue Aug 31 21:36:03 2004
Subject: Forwarding Tom Reed on Dr. Yury and Samovars
Message-ID: <v01540b00b20ec191e6b3@[204.133.28.34]>

Stovers:

This message came in

>Ron, Yury et al:
>
>I presume that the classical Samovar uses charcoal. If one wanted a
>biomass version, the gas would have to be completely burned before entering
>the chimney heat exchanger, or incomplete combustion products would coat
>the chimnney pipe and reduce heat transfer.
>
>TOM REED

The ones I saw in use were along the road in Kyrgyzstan, being used
by roadside vendors to heat water for tea for travelers. They were top fed
every five or ten minutes (I think - I didn't time it) by a one or a few
small slivers of wood (maybe several times the size of a pencil). There
certainly would be a good bit of continuing charcoal at the bottom, but
there also was certainly flame periodically.

Tom may be right about the chimney heat exchanger clogging up - but
Dr. Yury is presumably our best expert on this. Or perhaps the periodic
flame up works in some way to self-clean. They certainly were not smoking
badly; it seemed like a clean burn (but this was about five years ago and I
could not be a close observer). I'll bet there are many millions in use.

Dr. Yury? (and please note my request for more information on
samovar efficiency)

Ronal W. Larson, PhD
21547 Mountsfield Dr.
Golden, CO 80401, USA
303/526-9629; FAX same with warning
larcon@sni.net

From english at adan.kingston.net Mon Aug 31 21:42:22 1998
From: english at adan.kingston.net (*.English)
Date: Tue Aug 31 21:36:03 2004
Subject: Thermette Kettle
Message-ID: <199809010152.VAA25533@adan.kingston.net>

Dear Stovers,
Auke Koopmans has sent along some information on the Thermette, a
water heater similar to the Oz Kettle which was mentioned earlier.
Check it out on the Stoves Webpage.

Alex

BioEnergy Lists: Improved Biomass Cooking Stoves

August 1998 Biomass Cooking Stoves Archive