Objectives: In a domestic biomass cook stove, the air supply plays a significant role in improving the overall combustion characteristics. The present research aims to numerically investigate the effect of air supply, division of air intake into primary and secondary air, and its optimization. > In a domestic biomass cook stove, the air supply plays a significant role in improving the overall combustion characteristics. The present research aims to numerically investigate the effect of air supply, division of air intake into primary and secondary air, and its optimization. Methods: The geometries of cook stove combustion chamber were prepared and simulated using species transport model with eddy-dissipation turbulent mixing. The stoichiometric amount of air was split into different ratios varying from 50:50 to 10:90 and simulations were carried out for each case. The computational model was validated and the concentration of CO2, H2O, O2, wood volatile and resultant temperature were compared and analyzed. Results: Species transport in the form of conservation of mass along with momentum conservation and energy conservation gave the spatial distribution of resultant species and spatial temperature distribution. The computational domain with feedstock inlet corresponding to the pyrolysis regime has yielded good results compared to that in the front. In this domain, the primary to secondary air ratio of 50:50 showed the best results due to the dominance of primary air utilization and, thus, less secondary air use even at higher elevations. With the maximum temperature near 1300 K, maximum relative CO2 production, and maximum feedstock utilization, the primary to secondary air ratio of 50:50 observed to be optimum. Conclusions: Due to the adequate intermixing of reactant species and uniform diffusion of product species along the combustion chamber's height, the computational domain with feedstock inlet corresponding to the pyrolysis regime has shown realistic conditions. The temperature profile and mole fraction of various species, thus obtained, can be used to design an efficient cook stove as the cross-section and dimensions of the combustion chamber and chimney relates to approach the desired division of air.
Keywords: Cook stove; Primary air; gasification; pyrolysis; secondary air; species transport; wood volatiles.