[Stoves] Natural draft TLUD turn-down

Thu May 22 16:47:31 CDT 2014

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 
  To: Stoves Bioenergylist 
  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
  To: 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 
    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

----------------------------------------------------------------------------
    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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