[Stoves] Natural draft TLUD turn-down

Thu May 22 17:38:51 CDT 2014

Dear Kirk

I have looked through the messages below and did not find what you are
calling ‘methods 1-4’.

Can you please copy to me whatever it was that is the source of the
comments? I would like to understand what you are referring to with these
different methods.

The layout and function as you describe do not apply to the Vesto so I was
wondering what you mean by a ‘pilot flame’.  The Vesto dies have a pilot
flame with air provided by three 8mm holes quite low in the chamber, well
below the secondary air inlets. This is relevant when the bottom of the
combustion chamber is blocked in order to run in a TLUD gasification mode.
Normally that is blocked with a circle of newspaper with a few knife slits
in it.

The pilot flame ensures that wood can be charcoaled and burned controllably,
or pellets (packed bed function) can be pyrolysed and then the char burned.
This function enables the user to load quite a lot of fuel into the stove
but burn it slowly – far slower than an ‘open fire’ would be able to. 

Thanks
Crispin

Otto,

Thank you for your lead on the Prime Stove, Dr. Nurhuda, and the Differ
group.

The Prime stove is an excellent stove and they are doing wonderful things in
Indonesia.  This is the type of activity that I would like my work to
support.

The Prime stove is however not a Method 2 stove.  It more resembles a Vesto
or Peco Pe.  The early secondary air inlets are too low to provide an
efficient pilot flame.  They were clearly designed to direct air at the char
and show no knowledge of the interaction of Method 2 type pilot flames with
the secondary flame.  If the lower holes were eliminated and replaced with
holes directly below (2 to 2.5 cm) the secondary inlets, then it would be a
Method 2 stove.  Possibly the stove would then get a 3.1 turn down ratio
instead of a 2.1 turn down ratio.  Please examine my document again to see
the difference.

The Prime stove is also not a Method 1 or 4 stove.  The secondary air is
directed straight in, not down the inner wall of the reactor.

Thank you for bringing up the topic of patents.  I have designated the
methods of turn down with numbers rather than names to avoid any implied
thoughts or feelings of ownership on my part.  This is partly in case a
conflict comes up with a patent at some point.  I have no desire or intent
to violate any patents, and if such a conflict comes up I will stop any
actions which might violate a patent or do any harm to any business, group,
or individual.  My intentions are to improve turn-down capability in TLUD
cook stoves and all are welcome to use or not use anything I come up with.

I can name my test stoves as I please and need not your permission or
approval.  Wonderwerk is a name not a nick name.

Respectfully,

Kirk Harris

Santa Rosa, CA. USA

----- Original Message ----- 

From: Otto Formo <mailto:terra-matricula at hotmail.com>  

To: Stoves Bioenergylist <mailto:stoves at lists.bioenergylists.org>  

Sent: Wednesday, May 21, 2014 2:01 AM

Subject: Re: [Stoves] Natural draft TLUD turn-down

Kirk Harris, Paul A and Ron L,

I am not assuming that the Peko Pe, will pass the ISO IWA low power test as
a tier 4 stove, but I find it a bit odd that your method 2, is describing
very much how the Peko Pe used to operate and now operates, including an
adjustable primary air intake.

Robert, saw the similarity for the lower secondary air inlet in the
combustion chamber, just like the old type of Peko Pe from Uganda in the
1990`s and I noticed the adjustable inlet for primary air, like in the
newest model.

In a micro gasifier unit, like the Peko Pe, you can also easily “adjust” the
amount of fuel to be used for each cooking.

Just add fuel to a bit above the bottom plate and your flame will reach the
pot, any how, due to the secondary inlet and the gasification process. 

 A “Rocket” stove will produce more or less the same thermal efficiency, but
with a higher PM.

These types of stoves are of course more efficient than a three stone fire,
but the PM is very much the same as any open fire, apart from emissions from
a micro gasifier unit.

It would help, if a Rocket” stove was lit from the top, but still the strong
draft in that narrow chimney, will create toxic emissions and PM to flow
into the (air) room.  

I think you should also look into the Prime cookstoves, invented and
patented by Dr. M. Nurhuda, Professor of Physics, Brawijaya University,
Malang, Indonesia, when it comes to lower and power down the flame.

I guess he would not be “too happy” to find out that you are calling his
PrimeStove – Wonderwerk…………?

“Your method” 3, by lifting the char in the combustion chamber, has been
declined some time back, considered to be too complicated. 

We just put the remaining char into a standard charcoal stove, which you
will find all over the African continent, for further simmering. 

Good luck with your efforts and tests.

It is very much needed, but correct and proper references, should be
mentioned and not “nick named”, that`s all.

Otto 

  _____  

From: kgharris at sonic.net <mailto:kgharris at sonic.net> 
To: stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>

Date: Tue, 20 May 2014 11:38:15 -0700
Subject: Re: [Stoves] Natural draft TLUD turn-down

Otto and all,

The Peko Pe is an incredible stove and the man who created it is even more
incredible. I wish I had met Paal Wendelbo, but I missed out on that
privilege. I have met lots of other really incredible people though.

If the Peko Pe can pass the ISO IWA low power tests as a tier 4 stove then I
will agree with you. If not then I will continue my struggles with the
Wonderwerk test stoves in that direction. When I go to Stove Camp at
Aprovecho this summer, I want to see a TLUD with low power tier 4
capabilities, be it a Wonderwerk stove or someone else’s stove. Come on TLUD
folks, we're getting our butts kicked by the rocket people here.

Kirk Harris

Santa Rosa, CA. USA

----- Original Message ----- 

From: Otto Formo <mailto:terra-matricula at hotmail.com>  

To: Stoves Bioenergylist <mailto:stoves at lists.bioenergylists.org>  

Sent: Monday, May 19, 2014 11:56 PM

Subject: Re: [Stoves] Natural draft TLUD turn-down

Dear Roberto,

I very much agree with you.

The Kirk Harris "stove", looks very much familiar and alike the way the Peko
Pe has solved this issues and to me it is a REAL wonderwerk, so why call it
with a nick name: 
Wonderwerk TLUD ??

This issues can be and are partly solved by the Peko Pe consept - "Problem
no", Acoli tribe, Northern Uganda 1994 -95.

Otto

  _____  

Date: Tue, 20 May 2014 08:38:41 +0900
From: crispinpigott at outlook.com <mailto:crispinpigott at outlook.com> 
To: stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>

Subject: Re: [Stoves] Natural draft TLUD turn-down

Dear Roberto

I agree with your analysis. There is a lot of merit in keeping the secondary
flame in close proximity to the top of the fuel bed. The most important is
that the secondary flame is harder to put out with a slight breeze (because
it relights). The second is that when the primary air is turned down to
control the power, the secondary flame is able to remain hot enough to stay
alight. Combined with external, down-drafting secondary air preheating (not
like the Peko Pe) one can maintain the secondary air feed ration under
different primary air conditions. 

Read and heed! TLUD's are not succeeding in meeting the turndown ratios
required by ordinary cooking. To burn clean at different burn rates,
whatever the fuel, you have to control both the primary and secondary air
flows. 

While a 'double controller' can work, turning the secondary air down at
exactly the same time as the primary leads to a 2-3 minute period of very
high PM and or CO and VOC's because of the retained heat in the fuel bed and
stove body. This is worse if the combustion chamber is ceramic or cast iron.

If the secondary air feed it an automatic, buoyancy-driven ‎supply, it will
draw in additional air as required during the cooling-off period. This
explains the strange layout of the air supply in a Vesto Stove which tried
to address the problems inherent in David Hancock's (very advanced at the
time) 1984 Tsotso Stove (which is still in production). 

Regards 

Crispin in Seoul enjoying spring 

BBM 2B567C3

From: Roberto Poehlmann

Sent: Tuesday, May 20, 2014 02:28

To: stoves at lists.bioenergylists.org <mailto:stoves at lists.bioenergylists.org>

Reply To: Discussion of biomass cooking stoves

Subject: Re: [Stoves] Natural draft TLUD turn-down

Kirk,

this is a very interesting document, thanks to share it.

The method 2 is like the 12 holes configuration of the Peko Pe design in
page 9 of the following document:

http://www.adansonia-consulting.ch/document/Grass%20Cooker%20handbook_print.
pdf?PHPSESSID=3d064accc3efbdafd3b1133a13129f9a

Maybe this is the reason that the Peko Pe stove don't need an internal
chimney to operate. This 12 holes function also like 12 pilot flames,
maintaining the secondary flame hot.

I have replicated this design of the Peko Pe, and in operation, you can see
the pilot flames attached to the 12 holes.

Maybe the 4 holes concept in the middle of the combustion chamber can also
helps to maintain a slow power consumption. When the pyrolysis front reach
the middle of the combustion chamber, this "primary air" start to combust
the charcoal, adding heat to also support the flame.

Roberto Poehlmann

Valdivia Chile.

"

All,

Dr. Ron Larson, Dr. Paul Anderson and I have been working on the problem of
lack of turn-down in natural draft TLUD cook stoves.  We have found
considerable success.  Attached is a document introducing the results of our
labors.  All information is in the public domain.

K Harris
Santa Rosa, CA. USA

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