Performance Evaluation and Heat transfer studies on Biomass Gasifier cook-stove

ABSTRACT Emissions from solid fuel combustion to indoor, regional and global air emission inventory largely depend on fuel types, combustion devices and other factors. The use of biomass cook stove is widespread in the domestic sector of developing countries, but these stoves are not efficient and generate high amount of air emissions. Approximately half of the world population and up to 90% of rural households in developing countries still rely on biomass fuels and use conventional three stone chulha to prepare their meals. Due to improper design of combustion zone and low thermal efficiency, it emits gaseous pollutants like CO, particulate matter, etc. In the present work, detailed experimental heat transfer studies have been conducted on commercial gasifier cook-stove and different designs of conventional stoves (chulha). Modifications in the existing designs of combustion chamber of commercial gasifier stove were also proposed to enhance the stove indicator parameters. From performance test results, it was found that gasifier cook-stove shows higher heat transfer efficiency and effective power delivery. This indicates a better performance when compared to the average thermal efficiency value of traditional stove. A complete energy balance for both the cook stoves has been worked out to assess the causes of heat losses and the reasons for the observed reduced thermal efficiencies. Heat transfer experimental results reveal that energy losses due to flue gasses, losses due to thermal inertia and heat losses due to radiation was fond to be lower for gasifier cook stoves when compared with conventional stove . We found that by optimizing thermal inertia of the stove and opening width of the combustion chamber (updraft type), which reduces radiation losses through fuel opening in case of gasifier cook stove, results in improvement of thermal efficiency by around 6-8 %. From emission test results, we inferred that average in-house PM and CO emissions were lower than that of conventional cook stove. It is therefore, necessary to design and develop techno-economically feasible biomass gasifier cook-stove and improving the energy efficiency of biomass clean burning cook stoves, which potentially offers a highly cost-effective alternative for easing the burden of buying fuel by urban poor as well as rural population.