Laboratory study of the effects of moisture content on heat transfer and combustion efficiency of three biomass cook stoves

The effect of wood moisture content on the performance and emissions of biomass-fired stoves was assessed using the laboratory-based water boiling test. This test yielded a number of performance indicators (time to boil water, specific fuel consumption and energy efficiency) when the stove was operated at both high and low power. When combined with emission measurements, combustion efficiency was investigated as well. This paper presents an integrated efficiency evaluation of the traditional open fire, an Aprovecho rocket stove from China and a “skirt” stove which were all tested each at 5%, 15% and 30% moisture content (wet basis) of wood. Results showed that an increase in moisture content increased efficiency up to a point. Extremely dry or over-wet fuel inhibited combustion efficiency. Overall, the type of stove exhibited a stronger effect on the total emissions than did the moisture level in the fuel.