| Boiling Point No. 10 - August 1986 |
Extracts from article (1986) by: Rahul Parikh of the Agricultural Research Centre, Bardoli, India
In the state of Gujarat only, there are hundreds of central and state government run hostels of residential schools. The kitchens of these hostels use thousands of tonnes of fuelwood for cooking. Our estimate shows that more than 6,000 tonnes of fuelwood can -be saved by introducing improved 'Community Cookstoves' in about 360 central and state government run residential schools in Gujarat.
Two types of community cookstoves have been designed and developed at the Centre. On`? for the big pots to boil foods (figure 1) and one for hot plates for roasting unleavened bread (chapatis) (figure 2). Each hostel kitchen needs at least two fuelwood stoves - one for different sizes of pots and one for a hot plate.
The Community Chulha is also made from bricks, sand and clay as the conventional ones. They can be constructed by a semi-skilled rural mason. Dimensions of the cookstove are decided with the general understanding that one cookstove will be used for one of the three pots of slightly varying sizes (plus or minus two inches). For the hot plate the design of the cookstove is the same. In that case the plate rests at the level of the pot bottom and the shield of the pot is eliminated. For square, round or rectangular hot plates the stove can be tailor made.
Main features of the community cookstove are:
1. grate for burning the fuelwood
2. fuel window for fuel charging and ash-pit window for air intake and ash removal. Both the windows have hinged dampers;
3. two or more layers of bricks as a shield to the cooking pots.
For the Community Chulha, length of the fuelwood has to be short enough to permit closing of the fuel window, which is to be opened only while charging the fuel. Air for combustion is sucked in through the ash-pit window below the level of the grate. Rate of fuelwood burning can be controlled by closing the hinged damper of the ash-pit window. Technically, the turn down ratio, which is reported to be not more than 2 in open fires, can be at least 3 with the shielded fuel and ash pit windows. The grate combined with a suitable shield can produce considerable improvements in fuel economy in the cookstoves. In addition, smoke is almost eliminated in the Community Chulha.
Testing and Field Studies
Both the cookstoves have been tested by the "Provisional International Standards" set up by a group of stove experts in December 1982. Water Boiling Test efficiencies of the Community Stoves are found to be 28% on average.
The Community Chulha has been adopted by about two hundred residential schools and some other institutions in Gujarat by end of March 1986. These Community-Chulhas have been constructed under the supervision of trained field workers.