Experimental Assessment of the Thermal Efficiency of an Improved Biomass Cookstove Fueled by Charcoal and Wood: Influence of Cooking Pot Size under Water Boiling Test conditions

Traditional biomass cookstoves widely used in developing regions exhibit low efficiency and high emissions, and although improved designs show potential, their thermal performance remains insufficiently studied, particularly regarding stove geometry, pot design, and key operational parameters. This study presents an experimental evaluation of the thermal performance of an improved biomass cookstove fueled with charcoal and wood, considering the influence of cooking pot size under standardized Water Boiling Test (WBT) conditions. Two pot sizes (No. 2 and No. 3) were tested during the three conventional WBT phases : cold start, hot start, and simmering. The performance indicators investigated included thermal efficiency, specific fuel consumption, specific boiling time, and fire power. Results obtained with charcoal showed that pot No. 2 provided lower specific fuel consumption, indicating better fuel economy, whereas pot No. 3 exhibited shorter boiling times and higher thermal efficiencies, particularly during hot start and simmering. For wood fuel, pot No. 3 demonstrated the best overall performance, reaching a maximum thermal efficiency of 27.42% compared with 19.29% for pot No. 2. The results further reveal that excessive fire power does not necessarily improve efficiency because high-power phases are associated with significant convective, radiative, and conductive losses. The novelty of this work lies in the combined analysis of fuel type and pot geometry under West African operating conditions. These findings provide useful design guidelines for optimizing improved cookstoves adapted to local domestic cooking practices.