[Stoves] Ph.D. Thesis on TLUD Stoves.

Sat Jun 29 14:18:21 CDT 2013

Ron and Paul O

Into the advertising leaflet of the Oorja stove is written “at end of flame very little aches is left” and I have tested the stove and can confirm it is right. I could see sparks up in the air above stove. The grid of cast iron 10 mm thick was white yellow about 900-1000˚C and quite dangerous to handle to take out some few char left.

With regards Paal W

From: rongretlarson at comcast.net 
Sent: Thursday, June 27, 2013 10:51 PM
To: Discussion of biomass cooking stoves 
Subject: Re: [Stoves] Ph.D. Thesis on TLUD Stoves.

Paul etal:

    I should have added there are some good discussions of the same stove/cylinder (glass) with numerous types of fuels.  And he shows they obey the same laws - can predict performance (front velocity, power level (?)  - given the superficial velocty.)

Ron

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From: rongretlarson at comcast.net
To: "Paul Anderson" <psanders at ilstu.edu>
Cc: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>
Sent: Thursday, June 27, 2013 2:44:07 PM
Subject: Re: [Stoves] Ph.D. Thesis on TLUD Stoves.

Paul:

     I know very little on the Oorja stove.  But the thesis is mostly (entirely?) on a packed bed, top lit.  It is on the migratory pyrolytic front (MPF) - so should be applicable to all TLUDs.   I would like to hear from any/all on whether I am getting the right reading about NOT consuming the char.

Ron

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From: "Paul Anderson" <psanders at ilstu.edu>
To: "Discussion of biomass cooking stoves" <stoves at lists.bioenergylists.org>
Cc: rongretlarson at comcast.net
Sent: Thursday, June 27, 2013 2:12:57 PM
Subject: Re: [Stoves] Ph.D. Thesis on TLUD Stoves.

Ron,

I am in Uganda now and have not had a chance to see the thesis.   Thank you for the comments.

About #3, the Oorja stove is rather heavy for turning over, has a smallish fuel chamber meaning not much char and only short TLUD burns, and has a loose cast iron cup in the bottom that would fall out if the unit is tipped over to remove the char.   It is designed to NOT be tipped over for saving char.   

It is intentionally designed to have continuous burning with the fire in the bottom consuming char.   And when doing that, the Oorja is NOT operating in the TLUD mode which is specifically characterized by the migratory pyrolytic front (MPF), but the Oorja is not with MPF after the rather small initial load of fuel has been pyrolyzed.   

Therefore, the Oorja (and most others with forced air FA) essentially is NOT a TLUD because it is operated without the MPF except for the initial batch of fuel.

I will be addressing this topic more at the Stove Camp at Aprovecho on 22 - 26 July.

Paul

Paul S. Anderson, PhD  aka "Dr TLUD"
Email:  psanders at ilstu.edu   Skype: paultlud  Phone: +1-309-452-7072
Website:  www.drtlud.comOn 6/27/2013 2:43 PM, rongretlarson at comcast.net wrote:

  Julien  and list

  1.  Thanks very much for providing this cite.   I have read most and find it to be a well done thesis.   I wish we had more like it.

  2.  The concepts of char and TLUDs are in here thoroughly.  But nothing on the idea of a stove designed to make char.  All char is presumed and desired to be consumed.  

  3.   My conclusion (would like to hear more) is that a good case is made (not intentionally) for NOT consuming the produced char in a TLUD  (this one fan-powered and widely sold in India as the "Oorja"  (started by BP)).  Very little gain in overall efficiency as the char is consumed.

  4.  A major advance was his study of the importance of ash in this "char" period as a poor radiator - thereby responsible for (undesired) high char temperatures.

  5.   Most everything shown as a function of superficial velocity (Vs) - with 16-17 cm/sec shown as key dividing point in stove behavior..  Above which velocity one swtches from char production to char consumption.   I have not seen this before.

      For his highly automated fan system, measuring Vs was apparently not so difficult.  Anyone able to give a way to get an easy estimate of Vs, when there is only natural draft?

  6.  Quite a bit on the importance of low emissions of CO.

  7.   Good information on both the experimental and computational side of top-lit (packed bed) stoves.  Not much here for rocket stoves.

  Have I got #3 right?

  Ron

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