Thermal performance of a central annular cavity vessel with fins of a box-type solar cooker

Abstract

Solar cooker is an alternate device used for reducing the problems of energy supply for cooking needs, especially in rural households. Though solar cookers have been commercialised in rural and other domestic areas, further research is still required to enhance the efficiency of the solar cooker. Previous studies have helped to ascertain that the central annular cylindrical hole in the cooking vessel reduces the length of the heat-transfer path and provides higher heat-transfer rate to the water kept in the vessel. Convective heat transfer can be further increased by providing additional surface area in the cylindrical hole. This study proposes a new cooking vessel with central annular cavity and fins attachment that will help in increasing the heat-transfer rate to the cooking vessel. Experiments are conducted with three types of vessels, i.e. conventional cooking vessel, cooking vessel with central annular cavity and cooking vessel with rectangular fins in the central annular cavity. For the annular cavity with fins vessel, a peak temperature of 98°C is observed. The maximum temperature difference of 30°C has been observed between annular cavity vessel with fins and conventional vessel. As the height of the lug is also expected to play an important role, experiments are conducted to determine the effect of lug height on the heat transfer to the cooking vessel. This study indicates that a lug height of 9 mm is optimum for maximum heat transfer to the cooking vessel.