[Stoves] ***SPAM*** RE: ***SPAM*** Re: Crude brick TLUD for developing countries

[Crispin Pemberton-Pigott]

Dear Kevin

Very nice.  In terms of function, lighting, and body shape, it is identical to the Basenjengo Magogo which is a method of burning coal, popularized several times in South Africa, notably in the 70’s and in the 90’s.  Basenjengo Magogo means, “make it like grandmother does”.   It is also known as “the Scotch method” from at least 125 years ago.

I have some suggestions:


  1.  Make the pot rests shorter, meaning the clearance between the pot bottom and the stove top.  You suggest plastering it with mud which would reduce of from the recommended 30mm, so measure.  A stove if that size and power requires between 8 and 10mm of pot-stove clearance.  It acts as a choke on the total gas flow which in many cases is far too high.  High air flow means cooler exhaust which is a heat loss.
  2.  At the bottom, make two holes half the size, opposite each other.  I realise this makes it more difficult to construct because removing one brick is very simple.  However once the fuel is falling and the space in the chamber is more open, having all the air enter from one side is a clear disadvantage for two reasons: the flames run to one side, and it tends to cook “off-centre”.
  3.  In the same regard, you could make the two half-brick sized hole on opposite corners, not in the centre of the side.  This will at some point tend to rotate the flames which lengthens the flame path (free) which improves the chances that the smoke will burn.  This can be checked very easily. See if there is a visible improvement, side by side.  If there is, the improvement is a lot more than 15% because visual change has to be about that big to appear definite.
  4.  If you can, place two ¼ holes in the centre of two opposite sides in layer 4, out of 6, or 3 out of 5.  This will introduce a portion of secondary air.  This will not be needed it you have too much air already, however there is a principle at stake.  With that fuel loading method and top lighting, towards the end there will be a large increase in the heat output as the last ¼ or 1/5th of the fuel burns.  If there is no break in the draft it will tend to smoke much more because all the air is going to gas creation and none (save by chance) to gas burning.  When turning down the fire using a brick or partial brick in the hole(s) the secondary air will continue to flow and the smoke produced will the reduced (quite a bit probably).
  5.  If you were to place one of your rock beds at the bottom and have a removable brick at later 2 through one of the sides, you could push in some stick fuel later and continue cooking indefinitely.  Because it would be loose some air would leak in but this is trivial.

Thanks for your continuing innovation.

For those wanting to build a more permanent version of this please check out the Esperandza Stove from Malawi which is public domain and similarly inexpensive.  Tens of thousands have been built.

Best regards
Crispin


From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of K McLean
Sent: Thursday, November 2, 2023 7:58 AM
To: Stoves and Biofuels Network <stoves at lists.bioenergylists.org>
Subject: [Stoves] ***SPAM*** Re: Crude brick TLUD for developing countries

Here is a link to the video.  I gave a bad link above.
https://drive.google.com/file/d/1LzxhdfqVVmxUILnlajR3znF8CaauhbOu/view?usp=sharing

On Thu, Nov 2, 2023 at 8:53 AM K McLean <kmclean56 at gmail.com<mailto:kmclean56 at gmail.com>> wrote:
Here is a video<mailto:stoves at lists.bioenergylists.org> demonstrating how to make and use a brick TLUD.  It works great, women love it.
1. It uses almost any fuel:  maize stalks and cobs, rice straw, dung, elephant grass stalks, sticks and twigs, etc..  So it allows women and girls to stop collecting firewood from forests and use renewable fuel that is nearby.
2. It is cheap to make and easy to use.  36 bricks usually cost under USD 1.
3. It is batch fed so cooks can light the top and leave the kitchen to do other things.  It will burn untended for 15-40 minutes, depending on the fuel.
4. There is much less visible smoke than from wood in three stone cookstoves.
5. It makes char that can be used as biochar or to make briquettes.

Has this been done before?  I'm presenting on it next week at the IBI biochar conference.  I don't want to present it as novel if it is not.

Thanks,
Kevin McLean
Sun24
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