ABSTRACT

 The design, development and comparative performance evaluation of an integrated passive indirect solar drying system with different heat storage material was undertaken. Brick, mixture of brick and palm kernel shell, palm kernel shell (PKS), and aluminum sheet with pebbles which are commonly available materials were used as heat storage materials respectively. Sliced tomato samples were used as product to be dried, although the drying was preliminarily done to test the performance of the dryers. The dryer was evaluated based on improvement of the ambient condition with the dryer condition which include relative humidity and temperature ofthe collector and drying chamber. Results of the performance evaluation showed that the average collector, chamber and ambient temperatures for brick, mixture of brick and palm kernel shell, palm kernel shell (PKS) and aluminum sheet with pebbles was 37.8°C, 36.3°C and 28.8°C ; 37°C, 35°C and 28.8°C; 35°C, 34.5°C and 28.8°C; 37.5°C, 35.5°C and 28.8°C respectively. Average solar insolation during this period was 139W/m2. Result ofthe Analysis ofthese dryers revealed that the solar dryer improved the minimum ambient temperature by 1.5°C compared to brick, 1°C compared to mixture of brick and PKS, 0°C compared to PKS and 0°C compared to Al. Additionally the solar dryer reduces the average ambient relative humidity by 10.76% compared to brick, 8.7% compared to mixture ofbrick and PKS, 3.7% compared to PKS and 8.4% compared to Al. Based on performance evaluation brick was identified as a good thermal storage material compared to other materials considered.