BioEnergy Lists: Improved Biomass Cooking Stoves

From mheat at mha-net.org Fri Nov 1 07:48:47 1996
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:35:02 2004
Subject: Introduction
Message-ID: <199611011246.HAA10337@nic.ott.hookup.net>

At 07:36 PM 31/10/96 -0700, you wrote:

 

 

From mheat at mha-net.org Fri Nov 1 15:09:53 1996
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:35:02 2004
Subject: Introduction (Repost)
Message-ID: <199611012007.PAA22740@nic.ott.hookup.net>

At 07:36 PM 31/10/96 -0700, you wrote:

 

 

From mheat at mha-net.org Fri Nov 1 17:45:14 1996
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:35:02 2004
Subject: Introduction (Second Repost)
Message-ID: <327A7CC3.6692@mha-net.org>

At 07:36 PM 31/10/96 -0700, you wrote:

 

 

From mheat at mha-net.org Sat Nov 2 07:38:07 1996
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:35:02 2004
Subject: Try this again
Message-ID: <327B4002.6130@mha-net.org>

Not sure what is going on here, but here's a third repost:

>Could you describe what the loading pattern is to achieve low emissions
>(and alternatively high emissions).
>
>Ron Larson
>

All loads are in the range of 20 kg., so we are trying to ignite a large
pile of fuel from a cold start. 75% of the emissions occur during the
cold start phase.

The first important item is the location of the air supply. We are still
playing with that, but we know where it should NOT go. If the combustion
air comes up through a grate in the floor of the firebox (underfire
air), there is too much initial release of volatiles, which then get
quenched by the cold fuel pile sitting on top. In addition, we've
measured excess air levels as high as 1200% and overall efficiency
(stack loss method) as low as 40% with underfire air.

Just to put some numbers on the emissions: we are measuring particulates
(smoke, i.e. microscopic tar droplets, some soot particles, a small
amount of flyash) According to US-EPA audited in-home field test data, a
conventional open fireplace emits about 20 grams of PM per kilo of fuel,
a conventional stove about 15 g/kg, an EPA certified stove about 7 g/kg,
an underfire air masonry heater is 5 g/kg and an overfire air masonry
heater is 1.2 g/kg.

The problem with conventional (airtight, heating) stoves, of course, is
that you are attempting to control the burn rate with the combustion air
supply. You can only turn the air down so much before you switch from a
flaming to a smoldering fire. The emissions ratio between these two burn
phases can be 100:1.

Back to masonry heaters, where we avoid the bulk of these problems by
using an optimized burn rate combined with heat storage: Our concern
here is the startup. With large North American fuel loads, we got the
best numbers with larger wood (6" diameter). We stack it log cabin style
inside the firebox. The trick is to get a good hot fire going fast, but
to ignite the pile in a controlled way. We do this by bringing air in at
the front, and placing the kindling in front of the pile. The front of
the pile ignites first, and soon there is a large flame ball in the
space above the pile (you need a tall firebox to avoid quenching). If
the whole pile catches at once, there are just too many volatiles at
first, due to surface drying of the fuel and the lack of a char or ash
layer on the surface of the fresh fuel. Right now we are providing extra
air at startup by cracking the loading door open about 1 -2 cm for 15
min. There is a real clear indicator when you are burning rich during
startup because you will get a very large CO spike. Normally, CO is
around 0.1%, except during the charcoal phase (tailout) when there is a
characteristic peak.

These considerations would be different for a continuous burn stove, or
a stove with a smaller firebox (our firebox is about 50cm x 50cm). With
the new EPA stoves, they have done some impressive things in reducing
the critical burn rate (point where burn switches from flaming to
smoldering), using refractory insulation to keep temperatures up and
finely tuned secondary air systems.

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

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

 

From larcon at csn.net Sat Nov 2 12:06:31 1996
From: larcon at csn.net (Ronal Larson)
Date: Tue Aug 31 21:35:02 2004
Subject: Try this again
In-Reply-To: <327B4002.6130@mha-net.org>
Message-ID: <Pine.3.89.9611021046.A2677-0100000@teal.csn.net>

 

Norbert: Third time's a charm! Thanks for your useful description. Just a
few more questions for clarification - because I have only been
experimenting with cook stoves and I hope that your type of company can
increase the use of wood stoves for space heating here in the US.
What is the third dimension (height) of your firebox?
What is the burn time?
If an hour, would you say this is a 100 kW heater?
How much storage (tons of brick?)? Is there then only radiated
energy to the household - or is there some passive or forced air
retrieval of energy from storage?
What height of chimney - and is the path artificially lengthened
to achieve greater storage?
Do you sell only one size of stove?
Should one strive for one firing per day?
If you had a mild day, should you fire with 5-10 kg?
Is this like the traditional Scandinavian household systems?
Given a worst case stove efficiency of 40% - what is the best
and/or typical?
What is the first cost and relative economics of your stove VS.
gas and electricity?
Do you have to build each unit separately or do you sell a
packaged unit of some type?
Do you have only a single air supply?
What size air port and at what height above the firebed?
How often does the homeowner have to adjust this air supply
opening - should it be closed after the fuel is gone?
Can you compare your 1.2 g/kg PM with other polluting sources -
such as coal fired electric power plants? What is the current
legislation on using wood burning stoves relative to this parameter?
Do you only see smoke during start up? - how long does start-up last?
Where does one find literature on the "EPA stove"?
What did you mean by "finely tuned secondary air systems."? It
doesn't seem that secondary air should be able to reduce the critical
burn rate. Can you state anything quantitative about this critical burn
rate (I guess in kg/hr or kW - or maybe this should be normalized by the
firebed area.)
Where does this EPA in-home testing occur? How does it get
reported? Is it considered well done?

This list got out of control - sorry!. But it seems that you are doing
very well in reducing pollution and this topic is certainly of interest
in this group. I don't see a way that a charcoal-making stove will work
for space heating - but I will start thinking about it. Thanks in
advance for anything you can add.

Ron Larson

 

From mheat at mha-net.org Sat Nov 2 14:33:07 1996
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:35:02 2004
Subject: Try this again
Message-ID: <199611021930.OAA17900@nic.ott.hookup.net>

At 10:04 AM 02/11/96 -0700, you wrote:
>
>Norbert: Third time's a charm! Thanks for your useful description. Just a
>few more questions for clarification - because I have only been
>experimenting with cook stoves and I hope that your type of company can
>increase the use of wood stoves for space heating here in the US.
> What is the third dimension (height) of your firebox?

20" high, with a 3" throat at the back into an upper chamber. The basic
design is known as a contraflow heater or a Finnish heater.

> What is the burn time?

2 hrs.

> If an hour, would you say this is a 100 kW heater?

Yes, I ballpark it at around 50 KW.

> How much storage (tons of brick?)? Is there then only radiated
>energy to the household - or is there some passive or forced air
>retrieval of energy from storage?

Approx 3 tons of storage. All the heat is radiated (at a surface temperature
of about 60 Centigrade, with some accompanying low grade convection, about
50%). Location is therefore important.

> What height of chimney - and is the path artificially lengthened
>to achieve greater storage?

Chimney height depends on the house, typically 20 - 30 ft. Path is
artificially lengthened inside the heater itself by two parallel 3.5" x 24"
x 72" downdraft channels, so that the exit into the chimney is at floor level.

> Do you sell only one size of stove?

Standard firebox is 18" wide, which used to be the largest size you could
build that could endure thousands of firing cycles. We now build a 22"
firebox, because we've been able to reduce the burn rate a bit.

> Should one strive for one firing per day?

One firing is typical. For a 50 lb load this results in a 2 - 3 kW output
over 24 hours. Firing on a 12 hour cycle doubles this to 5 - 6 kW maximum
output.

> If you had a mild day, should you fire with 5-10 kg?

You could, but typically we would just fire every other day. It depends on
the house. Ours has a lot of thermal mass, so cools very slowly.

> Is this like the traditional Scandinavian household systems?

Yes, this system is traditional in Finland, and is all they build (about
30,000 units per year for a population of 4 million)

> Given a worst case stove efficiency of 40% - what is the best
>and/or typical?

We're getting 70 to 75%. Theoretical maximum, using American definition of
efficiency, is about 80%. There's about a 13% unavoidable latent heat loss
with 20% moisture wood. (Latent heat loss is not counted in the European
definition of efficiency, so you have to subtract about 13% from a European
number).

> What is the first cost and relative economics of your stove VS.
>gas and electricity?

We sell a heater core, delivered and installed for about $4,000. It does not
include a foundation, a 4" masonry facing, or a chimney. You could build
your own and save some money, although the hardware is expensive. It is
uncompetitive with natural gas in urban areas of Canada, which is extremely
cheap. Most of our clients live outside of metropolitan areas and have ready
access to cordwood. I pay about $0.02 per kWh of delivered heat for cordwood
and $0.09 for electricity.

> Do you have to build each unit separately or do you sell a
>packaged unit of some type?

We precast refractory components that we combine on-site with locally
obtained standard firebricks. It takes about a day to construct a core this
way, versus about 40 hours to handbuild one from firebricks (lots of cuts on
the diamond saw).

> Do you have only a single air supply?

Yes.

> What size air port and at what height above the firebed?

3/4" x 16" airport aimed horizontally at the floor of the firebed. I don't
believe that this is the ultimate location, but so far nothing else has
performed any better.

> How often does the homeowner have to adjust this air supply
>opening - should it be closed after the fuel is gone?

Yes. There is also a sliding plate shutoff damper in the chimney flue that
gets closed after the fire is completely out.

> Can you compare your 1.2 g/kg PM with other polluting sources -
>such as coal fired electric power plants?

It's a lot more than a coal fired electric power plant. On the other hand,
there is no sulfur and no net CO2.

What is the current
>legislation on using wood burning stoves relative to this parameter?

In the United State, woodstove must be EPA certified (since 1992). For
non-catalytic stoves the limit is 7.5 grams of PM per hour.

> Do you only see smoke during start up? - how long does start-up last?

Yes, for about 5 minutes. You also see a lot of steam because flue
temperatures are very low.

> Where does one find literature on the "EPA stove"?

Go to a stove store in the US or Canada. Ask for literature on "Quadrafire"
stoves, for example which are one of the better brands. We have a number of
technical papers on our website. A good one is

Design and Operating Factors Which Affect Emissions
from Residential Wood-Fired Heaters: Review and Update
Paul Tiegs
OMNI Environmental Services
PO Box 743
Beaverton, Oregon 97075 ,

located at http://mha-net.org/html/papers.htm

> What did you mean by "finely tuned secondary air systems."? It
>doesn't seem that secondary air should be able to reduce the critical
>burn rate. Can you state anything quantitative about this critical burn
>rate (I guess in kg/hr or kW - or maybe this should be normalized by the
>firebed area.)

Airtight stoves are not my area of expertise. I've seen a Quadrafire stove
burn at a very low rate and was quite amazed by what I saw.

> Where does this EPA in-home testing occur? How does it get
>reported? Is it considered well done?

The bulk of it has been done under contract by OMNI (see above). Some has
also been done by Dr. Dennis Jaasma's combustion lab at Virginia Tech in
Blacksburg, VA. Yes, it is considered well done and is the definitive work
in this area until somebody else decides to get involved. The issue here is
to mimic the actual pollution in the local airshed. Since PM is a complex
and variable mixture of chemicals which condense at various rates upon
mixing with atmosheric air and cooling, you either have to go out into the
field or use a dilution tunnel in the lab. The Europeans define particulates
differently ("staub" in German). In North America, a particulate is an
aerosol. If you sample it hot from the stack the way the Europeans do, it
won't be a particulate yet.
>

>This list got out of control - sorry!. But it seems that you are doing
>very well in reducing pollution and this topic is certainly of interest
>in this group. I don't see a way that a charcoal-making stove will work
>for space heating - but I will start thinking about it. Thanks in
>advance for anything you can add.
>

My only experience with charcoal stoves is with my hibachi, and from reading
books such as Samuel Baldwin's. Seems a shame to waste all those volatiles
when you make the charcoal - I guess transport costs are the big issue with
cordwood in the third world. I always like to see the highest entropy form
of energy used that will do the job - I need electricity to run my computer,
but not to heat my house. Charcoal is nice for cooking, but seems wasteful
for mass space heating, where you only need low grade heat. We've been using
a North American cordwood cookstove for about 23 years - it makes sense
here, but probably not where fuelwood is at a premium.

Best........Norbert Senf

----------------------------------------------------------
Norbert Senf email: mheat@mha-net.org
Masonry Stove Builders website: www.mha-net.org
RR 5 Shawville fax: 819.647.5092
Quebec J0X 2Y0

 

 

From 73002.1213 at compuserve.com Mon Nov 4 11:07:05 1996
From: 73002.1213 at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:35:02 2004
Subject: End of Gasification/Stove Odyssey
Message-ID: <961104160235_73002.1213_FHM76-3@CompuServe.COM>

Dear Netpals: (Apologies to anyone who gets multiple copies - overlapping
lists.)

I am finally heading home, finishing my "gasification/stove odyssey". I arrived
here in Tokyo at 7:30 AM, & I don't fly to LA until 4:30 - but don't worry, I
won't bend your ear that long.

When I was a little boy my mother took care of me. In the army Uncle Sam took
care of me. Then I got married and Vivian has taken great care of me. However,
for the last six weeks the whole world has taken care of me, and my special
thanks go to those of you on this list who met me, wined and dined me, informed
me, helped me plan or kept me in their thoughts. (And thanks to United,
Lufthansa and Thai airlines for safe, on time flights and for not loosing my
baggage - and for this nice lounge to wait in.)

I believe I mentioned before my famous fortune cookie -

YOU WILL BE PAID TO GO AROUND THE WORLD, WITH YOUR LOVER

and Vivian's explanation that "lover" meant "laptop lover". In Bombay I asked
Mrs. Parikh if she could think of a better name for her than "TOSHIBA". She
thought a moment and came up with SARAKAWI, the Godess of Knowledge. So thanks
to SARA (and TOSHIBA) and her two batteries for "no headaches, no shopping
sprees".

My last stop was in Bangkok to see Bhatacharya at the Aisian Institute of
technology and Woraphat Arthayukti at UNOCAL Thailand. When I tried to visit
AIT travel was not possible because the Queen of England was going to the
airport. So we settled for a long phone call. Woraphat was a Royal Host,
arranging a lecture for me at the Petroleum Thai Institute, then loaning me his
office and finally entertaining me for dinner with his lovely wife, Chelermporn
and sending me to the airport in the UNOCAL car. A wonderful end to the trip.

My mother would be proud of my balanced diet: In Europe I ate mostly meat and
cheese; in Asia I ate vegetarian. My plumbing performed without need of
attention. I sent several LARGE packages home; I had laundry done in Stockholm
($120), Bangalore ($4) and Bombay ($1); I was just able to carry:

My LL Bean backpack/briefcase
My Banff courtesy satchel (home of Sara)
My Chinese rolling suitcase

My impression from talking to all my Internet friends is that most people in the
world speak some English. Not so! Scientists and professional people mostly
are fluent in English. However, many times, even in hotels catering to
foreigners I had trouble finding any Basic English speakers.

The purpose of the trip was to gather information for a "Survey of Biomass
Gasification" and it was very well served. Several major themes emerged:

Interest in renewable energy crashed in the mid-1980s following the discovery
that the "energy crisis" was largely perceptual, created by political forces.
There is now a renaissance of gasification technology for environmental/CO2
reasons and for supplying energy to off-grid locations.

There is great concern in Europe about the tars generated during gasification;
in Asia we think that this problem is greatly overrated for downdraft gasifiers,
and I personally believe that some new gasifiers being developed can be used
with NO tar cleaning (but requires cooling and some particulate removal).

Diesel engines converted to spark ignition gas engines are being tested as
replacements for the dual-fuel diesel engines thatwere used for power generation
during the 80s. It is surprising that this is being discovered so late in the
game.

There is an upsurge of interest in stove research and stove testing. There are
still 2-3 billion people burning too much wood to poorly cook their dinners.

There is still generous support of research and commercialization by US AID and
the European equivalents.

It has been a wonderful adventure - and now I have to "pay the piper", ie write
the book, probably not as much fun as the trip. So, if most of you don't hear
from me for a while you'll know I'm in my cave with SARA.

Love to all, TOM REED

PS I was met at customs in LA at 9 AM by my family including Vivian who flew out
here. So, after spending most of Saturday in Tokyo, I also spent another
Saturday in Long Beach. I believe that I am one day older than I would have
been if I hadn't travelled around the world. (Phineas Fogg in "Around the World
in 80 Days" noted the same effect.)

 

 

From gayathri at aero.iisc.ernet.in Tue Nov 5 10:27:47 1996
From: gayathri at aero.iisc.ernet.in (Gayathri)
Date: Tue Aug 31 21:35:02 2004
Subject: End of Gasification/Stove Odyssey
Message-ID: <9611060153.AA11873@aero.iisc.ernet.in>

 

 

From prasad at tn7.phys.tue.nl Wed Nov 6 05:44:24 1996
From: prasad at tn7.phys.tue.nl (prasad)
Date: Tue Aug 31 21:35:02 2004
Subject: On efficiency and co-production of charcoal
In-Reply-To: <Pine.3.89.9610310818.A11425-0100000@teal.csn.net>
Message-ID: <9611061032.AA15477@tn7.phys.tue.nl>

A non-text attachment was scrubbed...
Name: not available
Type: text
Size: 471 bytes
Desc: not available
Url : http://listserv.repp.org/pipermail/stoves/attachments/19961106/5176af44/attachment.cc
From larcon at csn.net Wed Nov 6 14:33:06 1996
From: larcon at csn.net (Ronal Larson)
Date: Tue Aug 31 21:35:02 2004
Subject: On efficiency and co-production of charcoal
In-Reply-To: <9611061032.AA15477@tn7.phys.tue.nl>
Message-ID: <Pine.3.89.9611061255.A12055-0100000@teal.csn.net>

 

Prasad:
My concern is that all stove efficiency formulas that I have seen
subtract the value of the energy remaining in the charcoal from the
initial energy content in the wood when determining the efficiency. I
don't believe this is justified - although it makes little difference
when the amount is small.

Ron

On Wed, 6 Nov 1996, prasad wrote:

> Dear Ron
> Our definition of efficiency is based on a stoves that uses all the fuel
> with no special provisions for charcoal recovery. Since your design is meant
> to recover charcoal, our definition requires modification.
>
> One problem you will face is that the calorific value of charcoal. I am
> assuming that it will not be pure carbon. That means that you will have to
> determine the heating value of the recovered charcoal.
>
> I hope this clarifies my note.
> Yours
> Prasad
>

 

From tmiles at teleport.com Fri Nov 8 19:48:19 1996
From: tmiles at teleport.com (Tom Miles)
Date: Tue Aug 31 21:35:02 2004
Subject: Bioenergy Email Lists and Commands
Message-ID: <3.0.32.19961108164518.00d45300@mail.teleport.com>

BIOENERGY EMAIL LISTS

The bioenergy mailing lists are hosted by the Center for Renewable Energy &
Sustainable Technologies(CREST) for industry, academia and government to
discuss biomass production and conversion to energy. There are four lists
at CREST.

o Bioenergy (bioenergy@crest.org)
Moderator: Tom Miles (tmiles@teleport.com)
(Other Volunteers are Welcome!)
Archive: http://solstice.crest.org/renewables/bioenergy-list-archive/
Digest: bioenergy-digest@crest.org

o Gasification (gasification@crest.org)
Moderators: Tom Reed (73002.1213@CompuServe.COM)
Estoban Chornet (Chornete@tcplink.nrel.gov)
Archive: http://www.crest.org/renewables/gasification-list-archive
Digest: gasification-digest@crest.org

o Anaerobic Digestion (digestion@crest.org)
Moderators: Phil Lusk (plusk@usa.pipeline.com)
Richard Nelson
Dave Stephenson
Archive:http://www.crest.org/renewables/digestion-list-archive
Digest: digestion-digest@crest.org

o Stoves (stoves@crest.org)
Moderators: Ronal Larson(larcon@csn.net),
Etienne Moerman (E.Moerman@stud.tue.nl)
Archive:http://www.crest.org/renewables/stoves-list-archive/
Digest: stoves-digest@crest.org

Current subscribers to the lists are engaged in the research and commercial
production of biomass crops and fuels, the conversion of biomass power in
commercial operating plants, the construction and testing of commercial
scale pilot facilities for combustion, gasification and anaerobic
digestion, testing and analysis of environmental impacts for bioenergy, and
promotion and planning of future bioenergy resources.

This is a cooperative, volunteer effort that is now in it's third year. The
lists are moderated and managed by volunteers. We appreciate the support of
the Center for Renewable Energy and Sustainable Technologies and the
National Bioenergy Industries Association for hosting the lists at their
site.

CONTRIBUTIONS

While there is no fee to subscribe to the list contributions are welcome
and will be necessary to sustain the lists. Please contact Tom Miles
(tmiles@teleport.com).

COMMANDS

To subscribe to the BIOENERGY Lists from any internet email address, please
send email to MAJORDOMO@CREST.ORG with the message

SUBSCRIBE list-name YOUR EMAIL ADDRESS <=three word command
(Example: subscribe bioenergy tmiles@teleport.com)

To post a message to all members on the list, please address it to
list-name@CREST.ORG
(Example: bioenergy@crest.org)

UNSUBSCRIBE list-name YOUR EMAIL ADDRESS <=three word command
(Example: unsubscribe bioenergy tmiles@teleport.com)

Note: If you send a subscribe/unsubscribe command for an email address that
is different from the one known to the list server - for example, you may
send a subscribe command on behalf of someone else - then your message will
go to the list moderator for approval.

OTHER COMMANDS - Send email to MAJORDOMO@crest.org with the command 'help'.

MESSAGE ARCHIVE
Messages are archived at CREST using hypermail. The archives can be viewed
and sorted by date, subject or thread using a WWW browser at URL
http://solstice.crest.org/renewables/bioenergy-list-archive/index.html (or
as indicated above). CREST (Solstice) also supports WWW, gopher and ftp
for renewable energy at Solstice@crest.org.

MESSAGE DIGEST
Each list also has a digest, a collection of messages that is issued
periodically. This may be useful if you want to receive messages in a batch.
Subscribe to the list-name-digest@crest.org as indicated above.
(Example: subscribe gasification-digest@crest.org)

World Wide Web
~~~~~ ~~~~ ~~~
http://solstice.crest.org/

Gopher
~~~~~~
gopher.crest.org

Anonymous FTP
~~~~~~~~~ ~~~
solstice.crest.org

You can contact CREST at +1 202 289-5370,
or by sending email to info@crest.org.

LISTS ADMINISTRATORS
Please direct questions to the bioenergy list administrators:
Tom Miles, Jr. tmiles@teleport.com,
Zach Nobel zach@crest.org
Andrew Waegel asw@crest.org

----------------------------------------------------------------------------
-------
Tom Miles, Jr. Thomas R. Miles
tmiles@teleport.com, tmiles@ortel.org Consulting Design Engineer
http://www.teleport.com/~tmiles/ 5475 SW Arrowwood Lane
Tel (503) 591-1947 Fax (503) 292-2919 Portland, Oregon, USA 97225-1353

 

From larcon at csn.net Sat Nov 9 16:45:47 1996
From: larcon at csn.net (Ronal Larson)
Date: Tue Aug 31 21:35:02 2004
Subject: Per Nielsen work
Message-ID: <Pine.3.89.9611091438.A19614-0100000@teal.csn.net>

 

Re - Per Nielsen's web site

I think that Per S. Nielsen mentioned his work on a controllable
stove some weeks ago. Yesterday, I was finally able to get to his web
site (http://www.ibe.dtu.dk/medarbej/psn/psn.htm).

Per is a doctoral student at the Danish Technical University.
The first article there shows a "pyrolysis gasifier". Per credits
Norwegian Paal Wendelbo for this design which has been tested at DTU and
apparently is being manufactured by Paal in Ghana. After a few pages on
3-stone (and small modifications) stoves, this article describes a
pyrolysis gasifier that is very close in design to that which Tom Reed
and I have been describing. He then describes efficiencies, CO and
particulate measurements, and tests in Ghana. I consider PerÕs work very
important and recommend this article to others on this list.

Despite the many apparent similarities in design, there seems to
these differences (Per - I apologize if I missed anything and hope that
you will clarify):
a. There seems to be no effort to intentionally generate
charcoal. All char generated is consumed after pyrolysis has ceased.
b. There seems to be no primary (or secondary) air control.
c. The primary motivation seems to be to pyrolyze grasses and
then combust the remaining char.
d. The grasses are loaded to the top of the pyrolysis/combustion
chamber - not halfway.

Specific questions:
a. I don't understand your boiling time differences in Table
1. I expect boiling to start as soon as you reach 100 degrees - you show
it doing so earlier by one minute once (Test 8) but almost nine minutes
later in another (Test 3) case. Can this be attributed to differences in
location of the thermometer? ShouldnÕt one time increment be enough?
b. Why did the efficiency drop by 10 points between Tables 1 and
2? Can you estimate efficiencies during different parts of the run?
c. You indicate you measured air flow in the tests of Table 2 -
but no air flow data is shown. Are any numbers available? Can you
estimate your excess air factor? And how it changes during a run.
d. Could you provide more detail on the instruments used to
measure CO and particulates. Have you any data taken on the 3-stone or
other stoves? (Per or Paal measured CO from .02% to .26% concentration)
Are these long term averages?
e. In connection with your Figure 2, you imply that these are
spot average temperatures with an instantaneous range that is similar
(400 600 C) but much more rapidly changing. Could you describe what you
see visually? Was this particular data taken indoors or outdoors and
could these variations be mostly due to the wind? Is this data typical or
unusual? We usually see a much more uniform temperature -unless there is
a wind.
f. You indicate that the stove is relatively cheap to produce -
what is that cost? ($ equivalent preferred)
g. What has been the acceptance of the users? How many?
h. You indicate a need for precision in construction - and more
so when you strive for full combustion. Do you think such precision
could be relaxed if you controlled the primary air flow?
i. You indicated a substantial performance benefit of using
grass over woodchips. Do you think this could be primarily due to the
shorter distance to the grass?
j. You indicated a preference for dry fuel - which I also have
found. Could you expand on why you made this point?
k. You are using 8 mm holes. How many in the three levels of holes?
l. You seem not to be using a grate at that bottom. Have you
tried it with a grate?
m. What is the meaning of the stove name - Peko Pe?

Thanks for informing us of your web site and your work - I think this is
a major contribution.

Ron Larson

 

From larcon at csn.net Sat Nov 9 17:39:10 1996
From: larcon at csn.net (Ronal Larson)
Date: Tue Aug 31 21:35:02 2004
Subject: Paul Hait stoves
Message-ID: <Pine.3.89.9611091519.A22239-0100000@teal.csn.net>

 

 

Notes on Pyromid:

Stovers: Yesterday, I saw another stove web site that I
recommend you look at (http://www.estore.com/pyromid/pyromid.htm). The
company president Paul Hait has recently joined our group. His set of
products have been primarily developed (over fifteen years) for the US
camping market; they are sold only through the Internet or by mail - not
through stores.

I have not yet seen or tested this stove, but I like the features
that he has emphasized:

High efficiency (claimed 75% fuel use reduction)
Multiple fuel capability (mostly charcoal)
High reflectivity materials with geometric (pyramid) focusing
Light weight, foldable (maybe low cost?)
Potential long life (stainless steel)
Careful fuel placement and spacing
Controllable air flow - from one side
An interior hot surface to encourage full combustion
Numerous attachments to add range of cooking capabilities

Paul has not yet contributed to our group, but IÕm sure he will.
I urge others to visit his Web site - to see if you think that this
(patented) design might have capabilities in the developing countries
many of you represent.

I have talked with Paul off line a little - but still haven't
gotten enough time to talk about this stove list previous dialog about
our many differing views of how to promote improved stoves - Imports vs.
Local industry manufacture vs. Local artisans, etc.. Paul's approach may
not be the eventual winner - but it certainly is different from anything
I've read.

Any questions for Paul? I hope Paul will comment on whether I
have caught his basic concepts and products - and his commercial interest
in expanding to developing country usage of his product line.

Ron Larson

 

From verhaarp at janus.cqu.edu.au Mon Nov 11 17:15:39 1996
From: verhaarp at janus.cqu.edu.au (Peter Verhaart)
Date: Tue Aug 31 21:35:02 2004
Subject: Efficiency and fuel comsumption
Message-ID: <9611112213.AA01641@janus.cqu.edu.au>

>From Piet Verhaart

To Grant

At 15:04 31/10/96 +0100, you wrote:
>In my view we are in danger of getting our aims confused (loosing the wood
>for the trees, perhaps) when we talk about efficiency.
Is efficiency thebest tool to achieve this aim? I believe not.
>
snip,snip
>

Yes, of course the performance of a stove, bicycle, automobile will depend
on the way it is operated. However, when a sufficient number of sensible
operators (assuming these exist in sufficient numbers) apply themselves to
obtain the highest (or the lowest) output for a given input, they will come
up with a figure that cannot be surpassed. That figure is likely to be
typical for the appliance tested. This is an accepted and, I think,
sensible practice.

Is heat transfer efficiency the alpha and omega of cookstoves?
NO, as is spelled out in many Eindhoven reports, even in my time,
efficiency is only part of the solution. The other property is the turn
down ratio, which in all woodburning cookstoves I know, is dismal.
In a stove used for deep frying potato chips, a turndown ration is probably
of minor importance and in this case should be designed to supply the
almost constant heat output rate needed at its highest efficiency.
For boiling the turndown ration is crucial to achieve a low specific fuel
consumption, if the cook refuses to use a haybox.

Cheers,
Piet Verhaart

 

From verhaarp at cqu.edu.au Wed Nov 13 00:38:34 1996
From: verhaarp at cqu.edu.au (Peter Verhaart)
Date: Tue Aug 31 21:35:02 2004
Subject: On efficiency...
Message-ID: <1.5.4.32.19961113043601.0067090c@cqu.edu.au>

>From Piet Verhaart

To Grant

At 15:04 31/10/96 +0100, you wrote:
>In my view we are in danger of getting our aims confused (loosing the wood
>for the trees, perhaps) when we talk about efficiency.
Is efficiency thebest tool to achieve this aim? I believe not.
>
snip,snip
>

Yes, of course the performance of a stove, bicycle, automobile will depend
on the way it is operated. However, when a sufficient number of sensible
operators (assuming these exist in sufficient numbers) apply themselves to
obtain the highest (or the lowest) output for a given input, they will come
up with a figure that cannot be surpassed. That figure is likely to be
typical for the appliance tested.

Is heat transfer efficiency the alpha and omega of cookstoves?
NO, as is spelled out in many Eindhoven reports, even in my time, efficiency
is only part of the solution. The other property is the turn down ratio,
which in all woodburning cookstoves I know, is dismal.
In a stove used for deep frying potato chips, a turndown ration is probably
of minor importance and in this case should be designed to supply the almost
constant heat output rate needed at its highest efficiency.
For boiling the turndown ration is crucial to achieve a low specific fuel
consumption, if the cook refuses to use a haybox.

Peter Verhaart 6 McDonald St Gracemere Q 4702 Australia
Phone: +61 79 331761 Fax: +61 79 331761 or 332112
E-mail: verhaarp@janus.cqu.edu.au

 

 

From 73002.1213 at compuserve.com Wed Nov 13 10:31:50 1996
From: 73002.1213 at compuserve.com (Thomas Reed)
Date: Tue Aug 31 21:35:02 2004
Subject: Copy of: Wendelbro stove
Message-ID: <961113152808_73002.1213_FHM66-2@CompuServe.COM>

I meant to send this to "STOVES" initially - sorry if you have seen it before.
RE: Copy of: Wendelbro stove

Ron et al:

I saw the Wenderbro stove operate while I was in Denmark - very similar to what
we have been doing for 10 years. I have a few pictures, and I talked to Per
Nielson. I tried to call Wendelbro in Norway without success. It would be
good to establish a dialogue with him.

Lunch? TOM REED

 

 

From BRAUNBECK at 495-simon.agrartech.uni-hohenheim.de Mon Nov 25 03:23:10 1996
From: BRAUNBECK at 495-simon.agrartech.uni-hohenheim.de (Claus Martin Braunbeck)
Date: Tue Aug 31 21:35:02 2004
Subject: plant oil as stove fuel
Message-ID: <70AECDC62C5@495-simon.agrartech.uni-hohenheim.de>

I learned from Ron Larson that you discussed about kerosene burner as
replacement for wood stoves. Actually, we are thinking to start a
project about using plant oil for stoves. The idear is to develop a
burner which uses the plant oil without any additive and to replace
charcoal, wood stoves or kerosene burners for cooking. Is there any
expiriences so far on what oil to use or is there already a burner
developed ? Thank you for your comments and information.

Claus Braunbeck

_______________________________________________________________________________
Claus Martin Braunbeck

Institute for Agriculture Engineering in the Tropics and Subtropics

Hohenheim University Garbenstr. 9 70593 Stuttgart Germany
Phone: 0711 / 459 2840 Fax: 0711 / 459 3298

E-mail: BRAUNBECK@495-simon.agrartech.uni-hohenheim.de
*******************************************************************************

 

From 73002.1213 at compuserve.com Tue Nov 26 07:11:51 1996
From: 73002.1213 at compuserve.com (Tom Reed)
Date: Tue Aug 31 21:35:02 2004
Subject: plant oil as stove fuel
Message-ID: <961126120811_73002.1213_FHM49-4@CompuServe.COM>

Dear Claus:

Every olive oil lamp for the last 10,000 years has been related to what you
describe. However, as the required flame gets larger it is more difficult to
vaporize the fuel and kerosene burners are very carefully designed to bring heat
to the circular wicks. Vegetable oils have a MUCH higher boiling point, so it
is VERY difficult to burn them in a controlled manner, though every deep fry
cook has accidentally had oil fires.

I tried burning biodiesel (Methyl esters, not glycerol esters) and even that is
difficult in a conventional lamp.

Be more specific in your question and I'll be more specific in my answer.

Yours truly, TOM REED

 

 

From mheat at mha-net.org Fri Nov 29 14:09:59 1996
From: mheat at mha-net.org (Norbert Senf)
Date: Tue Aug 31 21:35:02 2004
Subject: Masonry cookstove
Message-ID: <199611291907.OAA01179@nic.ott.hookup.net>

 

The following correspondence was received from Jorg Ostrowski, an architect
in Alberta who specializes in sustainable construction. I thought that it
might be of interest to the list. "Cookstoves", in this context, refers to
the typical North American or European kitchen range, with a cast iron or
steel cooking surface. "Heat transfer efficiency" refers to heat transfer to
the house, not necessarily the cooking pot.

Best........Norbert Senf
--------------------------------------------------------
>
>Date: Fri, 29 Nov 1996 10:26:04 -0400
>>To: Jorg Ostrowski <ash@freenet.calgary.ab.ca>
>>From: Norbert Senf <mheat@mha-net.org>
>>Subject: Re: masonry cookstove
>>
>>At 07:38 PM 28/11/96 -0700, you wrote:
>>>
>>>Norbert: Have you build the above with a water jacket? Even without that,
>>>what combustion and thermal efficiency could be expected? Thank you for
>>>your response. Have a warm day. Jorg Ostrowski
>>>
>>
>>Hello Jorg:
>>
>>Adding a water jacket to a cookstove is fairly simple. We had one hooked
up to our own cookstove (until we changed tank locations), and it easily
generated 60 gal of boiling water/day due to the fact that our cookstove is
on all day.
>>
>>We've never done efficiency testing on cookstoves, and I don't know of
anybody who has. I would expect overall efficiency to be in the 65% range -
you might be able to stretch this to 70-75% with an optimized system. I
wouldn't expect much effect from a water jacket, although I would steer away
from airtight cookstoves.
>>
>>A fellow near Kingston (Ontario) buys up old Findlay Oval cookstoves and
rebuilds them - he has a whole barn full of them, and you can get one with
new nickel in the 1500 - 2000 range.
>>
>>Building a masonry cookstove is expensive due to the cost of the imported
European hardware.
>>
>>We're building a custom system north of Toronto next week in a house
designed by Greg Allen that includes a Wamsler woodburning cookstove that we
imported from Germany - it is a compact one (24 x 24" cooktop) designed as
an insert into a masonry surround and cost a little over $2000 by the time
it got here. We used one a few years ago and the client is extremely happy
with it. The company also makes several other, larger models including
models with water jackets. You can get their catalogue from:
>>
>>Hannes Langeder, dir. Export
>>Wamsler Haus und Kuechentecknik (Munich)
>>Fax (49)89/5896-238
>>
>>Finnish hardware for masonry cookstoves can be obtained from:
>>
>>Maine Wood Heat Co.
>>RFD 1, Box 640
>>Norridgewock
>>ME 04957
>>207-696-5442
>>FAX 207 696-5856
>>
>>Best............Norbert
>>
>------------------------------------------------
>At 07:51 AM 29/11/96 -0700, Jorg Ostrowski wrote:
>>
>>Thank you for your response. We left room in our demo project for Larry
>>Dobson's cook stove. He claimed a 99.9% combustion efficiency on some of
>>his 3-stage gasifier combustor prototypes! An EPA report is available on
>>his work. I think you would find it of interest, if you are not familiar
>>with his work. Have a wonderful day. Jorg
>>
>
>Would love to get a copy of any test data that Larry Dobson has to back up
his claim. Items of most interest would be: either O2 or CO2 content of flue
gas, and flue gas temperature. Also moisture content of wood. CO content of
flue gas would be the indicator for combustion efficiency. Also - is this
real-world or lab data, and what is the fueling protocol?
>
>Typical combustion efficiencies that we've seen on masonry heater testing
are in the 97 - 98% range. Overall efficiency, which is (combustion
efficiency) X (heat transfer efficiency) is of more interest, as are
particulate emissions. If you burn 20% moisture wood, you lose about 13% in
latent heat loss (turning water into steam). You can't recover that unless
you go to a condensing flue. In addition, you need to run some excess air
(about 100%) and you need some stack temperature, unless you have mechanical
draft. This puts the maximum theoretical overall efficiency that you can get
in the 80% range. We've seen about 76% - 77% with masonry heaters.
>
>Best........Norbert
>
----------------------------------------------------------
Norbert Senf email: mheat@mha-net.org
Masonry Stove Builders website: www.mha-net.org
RR 5 Shawville fax: 819.647.5092
Quebec J0X 2Y0