Thermal Performance Evaluation of Box Type Solar Cooker using Stone Pebbles for Thermal Energy Storage

Abstract

A thermal performance of box type solar cooker with stone pebbles inside the cooker was tested with methodology described in ASAE international test standard. For the comparison, the cooker was put to test without stone pebbles, with un-coated stone pebbles and with black coated stone pebbles. The first figure of merit was found to increase with stone pebbles whereas the second figure of merit was found to decrease. However, the temperature profile of water and stone pebbles indicated that the cooked food can be kept warm for long time with stone pebbles inside the cooker. The test conducted with loading of rice resulted higher temperature around 65^oC in presence of black coated stone pebbles and less than 45^oC in case of test without stone pebbles. Further, rice loaded late afternoon at 3:00 pm was also cooked when black coated stone pebbles were inside the cooker.