Abstract:
The cost of conventional fuels used for cooking and boiling water is becoming more expensive and scarce, thus researchers are prompted to look into existing stoves utilizing agricultural wastes as fuels. Studies relating to heat losses through conduction, convection and radiation have been carried out in the past but it is necessary to study more and deeper into above areas to attain better understanding of the problem. Therefore the purpose of study for this research is to minimize heat losses from existing stoves through new developments for improving the stove efficiency. An attempt to arrive at standard method for measuring efficiency of stove has also been made. For this testing, initial efficiency measurement involved wood as fuel and water as material to absorb heat. The weight of wood was kept at i kilogram whereas weight of water was 2 kilograms and 0.8 kilogram for large pot and small pot respectively. The measured efficiencies are: average pot efficiency 84.1%, average stove efficiency 11.3%, and average overall efficiency 9.48% Developments performed on existing stove included 1. Increasing outside thickness of front stove wall from 5 centimetres to 7.5 centimetres and middle stove wall from 10 centimetres to.12.5 centimetres respectively. 2. A grate in combustion chamber was incoperated. 3. Reducing the diameter of port connecting the front and back stove from 11 centimetres to 8 centimetres and chimney from 9.5 centimetres to 7 centimetres respectively. 4. A damper at lower part of chimney was incoporated. 5. Redesigning the internal flue passage by placing a stone block made of cement, having length 11.5 centimetres, height centimetres, at the back stove. The results of° testing for the modified stove at 70 degree of damper, were found to be ; average overall efficiency 18.5%, average pot efficiency 93.0%, average stove efficiency 19.9%. These values were considerably higher than the previous ones measured from the original stove version, and highest attainment from various degrees of damper opening.