Comparative experimental investigations on a low-cost solar cooker with energy storage materials for sustainable development

Solar energy has been the focus of attention in recent decades due to its abundance, inexhaustibility, and cost-effectiveness. To promote solar cooking, a cooking pot integrated with energy storage is developed and studied. It features a concentric cylindrical arrangement, with the inner cylinder used for cooking and the outer cylinder used for energy storage. Solar energy was concentrated using a parabolic dish, with water serving as the load. The thermal performance during non-sunshine hours was analyzed using energy storage media.Initially, four cases were considered. In case 1, no energy storage medium was used, while in cases 2, 3 and 4, pebbles, stearic acid and erythritol were used as the storage medium, respectively. Water was heated to nearly 100 degrees C, and the results were analyzed for heat retention and temperature variations. The cooking pot using erythritol recorded a maximum instantaneous energy efficiency of 52 % and exergy efficiency of 37 %. In all four cases, the water was maintained at higher temperatures than the surroundings until the next morning, a maximum temperature difference of around 27-28 degrees C between the load and surroundings was reported during case 3. For high temperature cooking, sunflower oil was used as heating load with erythritol in case 5. A temperature difference of 8-9 degrees C higher than the case 3 was observed in case 5. Heat loss coefficient for case 4 was lowest i.e., 2.75 W/m2K. The payback period for the cooking unit was around 10 months considering the cost of energy saved and CO2 mitigation.