Influence of chimneys on combustion characteristics of buoyantly driven biomass stoves

This work examines whether a chimney has influence over the combustion characteristics of biomass within a stove. Experimental work as well as a simplified chemical kinetic model suggests that a chimney plays an active role in the performance of a stove by influencing the overall air-to-fuel ratio and subsequently the production of carbon monoxide. Two different stoves, operated at multiple wood consumption rates, were shown to run with steady state excess air of 300 % - 1250 %. The wood consumption rate was found to be independent of the chimney draft for both stoves. Increasing draft was shown to increase excess air. Draft served to cool combustion gases through dilution with makeup air. Increasing excess air decreased modified combustion efficiency in experiments and kinetic modeling. Increasing the frictional loss coefficient of a chimney by decreasing the diameter was shown to reduce CO production through a reduction of excess air.