Preliminary study on the utilization of geothermal energy for drying of agricultural product

Abstract

Indonesia is highly rich in natural resources. Volcanoes are spread over the Sumatra, Java, Bali and Nusa Tenggara islands in connection with a Mediterranean circumferential. The rest are volcanoes in Sulawesi, the Maluku archipelago and Northern Papua in connection with a Pacific circumferential. Volcanic activities create a potential source of geothermal energy. One of the famous geothermal energy centres in Indonesia is the Dieng plateau. It is also well known for tobacco and mushroom plantations. However, due to the heavy rainfall and drying problems the quality of the tobacco produced here is somehow still below the international standard. Therefore, a research into the utilization of geothermal energy for tobacco drying becomes very important. The research into the drying of tobacco leaves was conducted using an indirect heating system. The heat source for the dryer was geothermal steam. A certain amount of sliced tobacco leaves was placed into a tray dryer. Then the steam was kept flowing at a selected velocity. The moisture loss of the tobacco leaves was indicated by direct balancing of the sample and was then recorded at five-minute intervals. The experiment was stopped after one hour since the steam started to leak into the system. Using the moisture loss and time data, a drying rate curve was obtained. The effects of the steam flow rates and the sliced tobacco leaves layer thickness on the drying performance were investigated in this research. Experimental works showed that the increase of steam flow rate can enhance the drying performance, while increasing the layer thickness reduced the drying performance. However the high sulphur content in the steam caused rusting of the tray material and an unpleasant odour was produced.