[Stoves] Cost of stoves

[Crispin Pemberton-Pigott]

Dear Paal and All

This idea of making a replaceable combustor has additional benefits. The idea is already in use though it may not at first be obvious to a casual observer. 

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Dean and Paul are right if they also adopt the original idea with the TLUD-ND from the 1980ties and see the TLUD as a kind of a wrapping for the fuel; a unit loaded with energy to be put into a stove. Then you will have a lot of more possibilities. 

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I will post a photo of a stove I have recently seen in Cambodia which has a very substantial built-in brick and cement three-pot layout. There is a single chimney against the wall and three pot-holes. There is a wood fire space under or in front of each pot with a horizontal channel to the chimney behind it. 

This theme is used in Indonesia as well. I saw the exact same system used in urban Jogjakarta and a multi-pot single-fire version in rural Java. 

In all cases the hole is shaped so that it can take large woks and flat bottomed pots of different sizes from about 230mm to 900mm in diameter. The smaller pots are accommodated using reduction rings that fit the open hole and the pots. 

The point is the holes are substantial and the fires variable. When there is a desire to cook for a long time the ring(s) are removed and a taper-bodied stove that looks a lot like a tall JIKO is placed into the hole. This is a 'burner insert' or 'combustor' just as described by Paal. 

I have a photo of such a stove in operation. It has a charcoal burning stove dropped into the larger stove body. This can be done with all three holes if desired depending on what is cooking. 

As the concept is already well established, all that remains is to create other combustors that will either fit into the existing holes or stove body-combustor combinations that will accept appropriate pots. 

Further in our favour is that there is in Indonesia a (regionally?) established precedent for having an ash cleaning hole that is built into the floor below a clay grate. This satisfies the requirement to have a low overall height (about 300 mm) for the stove body. It means the combustor can be taller than 300 mm and still fit into the stove body. 
All the drop-in burners (which are stand-alone stoves if you take them out) can be improved as they stand so the new system performance should be much better than the baseline. 

Paal, in order to be able to get the PP or similar burners accepted in the same communities they will have to be 1) power controllable and 2) refuellable or the equivalent of refuellable such as a convenient swappable insert that can be managed easily. 

There is a stove in Mongolia that is copied from a Japanese brand 'Royal' which has two TLUD combustors connected by a Y-shaped channel to a common chimney. It is able toi cook constantly while swapping back and forth between two fires which can be run sequentially or in parallel. If one is started say, 1 hour before the other, the heat is continuous and the cook can re-charge the used one while the second burns. 

The big mis-match at the moment is the almost unchanging power output of the simple TLUD and the need for long term variable cooking for various foods, tea, palm sugar making, sea salt making, boiling chips and sterilising or heating water. People exercise quite a bit of control over the firepower during a burn cycle. 

For everyone's interest the most /hated/ aspect we could determine about stoves was the time interval between needing attention. At present it is about 5 minutes for domestic stoves. Although this will be investigated in the near future in detail, the people I interviewed rated a longer time away from the stove (perhaps 10-20 minutes) more valuable than fuel saving, smoke, ignition time, cost or fuel preparation (though objection to preparation of fuel was strong). 

The biggest opportunity I see at the moment with basically no change for the TLUD's is the load, fire and forget water steriliser. Lanny, don't forget. It can be a stand alone or a drop-in unit. 

Regards
Crispin in Carrying Place, Ontario (is there really such a place??)