[Stoves] Remarkable stove

[Crispin Pemberton-Pigott]

Dear Julien

Tank you for your analysis.  You mentioned the cooking efficiency with two stoves .  Do you know how that was calculated?

Thanks
Crispin


From: Stoves <stoves-bounces at lists.bioenergylists.org> On Behalf Of Julien Winter
Sent: Tuesday, June 15, 2021 9:36
To: Discussion of biomass cooking stoves <stoves at lists.bioenergylists.org>
Subject: [Stoves] Remarkable stove

Hi All;

Here are a couple of comments on the "remarkable stove"

1]  It would be a good idea to line the inside of the clay to give the stone some protection from heat.  Initially, the stove is run at low temperature to harden the clay, then later as the size of the fire is increased, the clay is 'fired in place'.  This lining would be easy to maintain.

2]  I like to think of designing a TLUD insert for this kind of stove as 'stove nesting' (as opposed to 'stove stacking').   If the user wanted to make char for charcoal or biochar, then the TLUD insert would be used given also the right circumstances where the user had good TLUD fuel, and a desire to run a stove unattended at a fairly constant temperature for 30-45 min.

This stove nesting may be the main role for a TLUD where wood or compressed fuel is not available all the time, or when agricultural residues are abundant.  TLUDs don't work well, or not at all, with leaves and agricultural residues.  For example, in rural Bangladesh, people tend to burn rice straw and leaves in their traditional and improved combustion stoves during the dry season, and conserve wood fuel for the wet humid season when burning wet loose fuel would be a smoky mess.

We can get high firepower out of a TLUD when burning small chunks of wood that form a fuel bed with an open pore-space giving low resistance to air flow.  I have achieved pore space temperature in a fuel bed of over 1100 °C in those conditions.  The fire power of the TLUD depends on its diameter, and the "remarkable stove" seems to be quite large.  If I burn vertical sticks of spruce lumber with open primary air flow, then stand back!  "Flash-fired goat."  One caveat to creating these kinds of conditions is that the metal cylinder will degrade faster than with cooler fires.

A TLUD nested in the "remarkable stove" could increase fuel efficiency, even when char is conserved, because the heat is focused on the bottom of the wok, and less heat is lost to warming up the mass of rock.   In Bangladesh, a  concentrator-ring TLUD conserving char had the same (or better) cooking efficiency (30%) as an 'improved' concrete stove burning all the fuel to ash.

Cheers,
Julien



--
Julien Winter
Cobourg, ON, CANADA
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