Improvement in thermal efficiency and emission control of domestic cook stoves (MS)

Abstract

Biomass holds substantial importance to cater day to day energy demands of people worldwide. Around three billion people globally rely on biomass viz. wood, crop residue, etc. to meet their energy requirements. Utilization of biomass as a source of energy started a long back when our ancestors learned the secret of fire. They started it with open fires and three-stone methods of cooking. These conventional methods were poor in terms of thermal efficiency and pollutants' emission. Pollutants emitted from these cook stoves pose serious threats to the health of people working nearby. However, as the time progressed subsequent modifications kept on taking place and various cook stove designs have evolved since their inception in domestic use. After mid of the twentieth century, intensive research has been carried out to improve the performance of cook stoves. The new concepts like provision of primary and secondary air, natural and forced draft establishment in the chimney, etc. sprung up. Significant improvements in thermal efficiency and pollutants emissions have been recorded in these cook stoves. Presented work in this thesis is an extension of these advancements. A design of cook stove wellequipped with the provision of primary and secondary air has been proposed. Multiple cook stove prototypes based on this design have been fabricated and an experimental test facility as per Bureau of Indian Standards has been set up. These prototypes have been tested in this test facility for thermal efficiency emissions measurement. A comparison has been made on the performance parameters of these prototypes. Furthermore, these prototypes have been compared with the existing cook stoves in literature. Results have shown good performance parameters for thermal efficiency and pollutants' emission in fabricated cook stoves. The highest thermal efficiency of 32.04% has been achieved, which falls in reasonably impressive range among existing cook stoves. Simulation techniques have been used to optimize certain parameters, whose analysis through experiments was challenging. Cook stove combustion chamber has been simulated for varying air supplies distributed between primary and secondary air inlets. The thesis concludes with the optimization of air supplies and primary to secondary air ratio of 50:50 has yielded best results for the proposed design.