Evaluation of thermal storage materials for solar cooker

Abstract

The performance of a solar thermal energy storage system using Lapland granite rock fragments 2-4 cm in diameter were assessed using a scaled-down model. The thesis deals with a selected medium that absorbs and stores solar heat during the day time and releases it when the sun was not shining. A storage rock bed of 5.89 kg with 30 cm x 30 cm base area and 6 cm thickness was placed at the bottom of a solar cooker and painted with black color to increase thermal absorption. The overall performance of a solar cooker i.e. the temperature with and without thermal energy storage (TES) materials was moni-tored for 20 hours. Solar energy is collected for 4 hours and the solar cooker temperature change was studied while solar radiation was zero. When TES materials were used the temperature was above 40°C for 3 hours and 30 minutes; however, without TES materials the solar cooker retain the heat for only 45 minutes. The average of solar radiation re-ceived over a specified period of time during 13:00 to 17:00 was estimated 798KJ. The average heat gained by TES material was 7.67W.The efficiency of the solar cooker with a storage system made of is about 14%.