[Stoves] Low tech, high performance dung and wood burning stove, Muminabad, Tajikistan

[Crispin Pemberton-Pigott]

Dear Dung Burners

 

It is not often we hear about high performance dung burning stoves. This is
your chance to participate.

 



This prototype is a two-hole heating and cooking stove with a drop on water
heating attachment in place. The water heater is an option. The system holds
41 litres including the heat exchanger. The temperature coming out rose to
90 C after cycling once through the pipes. 

 

The cooking power was measured at 2.65 kW which translates into a 10 minute
5-litre boil. The water heating power is 3.5 kW. The energy efficiency of
the package is 75%. It can cook with dung, though most people here co-fire
it with wood as they have access to both.

 

The dung only burning requires (or should have) a grate. There is no opening
downwards in the stove, no ash drawer. The grate is elevated at the back and
lies flat on the floor at the front. The CO/CO2 ratio is about 3% and the
stove cost is in the region of $35. 

 

The interior is lined with standard (local) bricks which are optional, in
order to reduce the initial acquisition price.  Options include the bricks,
the grate, the water heater, the tank with hoses and extended chimneys in
order to push heat into other rooms. 

 

Today we tested a coal stove that is less than half the size of this one and
demonstrated that we can get an effective delivery of heat into an adjacent
room without a pump (using thermosiphon only). 

 

An alternative model has a gas-to-air heat exchanger giving 75% efficiency
without the water heater in place. Other options include getting it without
the cooking holes - just water heating by placing containers on top of the
flat surface. After running for several hours the main body temperature on
the outside is 88 degrees C so it is much safer for children than a lot of
other stoves. The top is very hot, >300 C in places so cooking efficiency is
pretty good.

 

The new coal stove which can burn both terrible stony coal and good imported
coal almost entirely without visible smoke for a number of hours is an
immediate hit. With the Kyrgyzstani coal we saw today a CO/CO2 ratio of
0.06% with an excess air level of 35%. It was stable for extended periods at
0.15% at 45% EA. It will also be in the region of $35. It is a TLUD with
fixed secondary air and controllable primary air. It can cook one pot. 

 

Regards

Crispin in Muminabad

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