[Stoves] Natural draft TLUD turn-down

Tue May 20 13:38:15 CDT 2014

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 
  To: Stoves Bioenergylist 
  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

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  Date: Tue, 20 May 2014 08:38:41 +0900
  From: crispinpigott at outlook.com
  To: 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
        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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