Development of a thermal energy storage system Integrated with a cooking unit.

Abstract

The application of thermal energy storage technology in domestic cooking is a modern clean method where heat energy is stored in sensible or latent form. To extract the stored heat energy, specialized heat transfer surfaces should be provided to increase the cooking efficiency of the system. However, literature on how to extract the stored heat energy revealed that substantial amount of heat energy is lost either in pipes that transport the heat transfer fluid to the cooking unit or in the storage tank. In this study, a thermal energy storage system integrated with a cooking unit was developed, and its thermal and cooking performance experimentally investigated. Three sensible heat storage materials namely; water, oil and oil-rock pebbles were used as storage media and their thermal performances compared. An electric heater mounted inside a charging unit was used to simulate solar radiation and the system charged by thermosyphon principle. The thermal performance of the TES system was investigated interms of its effectiveness to store and retain heat energy for longer period. Cooking performance was tested during charging, after charging and after 14 hours of cool down period using parameters like efficiency of heat extraction and time to cook common foods like rice, macrons and beans. Results of the heat retention test indicated that oil and oil-rock pebbles TES systems retained more heat than water TES system. Based on this, rice and macrons were cooked after 14 hours of cool down period. High heat extraction efficiencies of 60.3 % and 64.9% obtained from the oil and oil-rock pebbles TES systems were comparable with those of the conventional cooking means. In conclusion, the results of this study show that integration of the cooking unit in thermal energy storage systems can greatly improve their cooking performance since heat losses are reduced.