Simulation of temperature and air flow distribution in coffee drying chamber using low enthalpy geothermal energy resource with thermosiphon technology

Utilization of geothermal energy is still dominated by indirect use for electricity generation, beside geothermal energy can also be used for direct application. Direct use is mostly using a low enthalpy geothermal resources (<150°C), one of the applications of low enthalpy geothermal energy is for drying process. Drying is a post-harvest method that aims to improve the quality of agricultural products by removing some of the water to an agreed an d safe limit, while microorganisms unable to grow and multiply. Coffee is one of the important commodity which has an important role in economic sector in Indonesia. In this study, the Computational Fluid Dynamics (CFD) method is used to determine and predict the drying chamber's temperature and air flow distribution patterns. The simulation process is carried out by varying the thermosiphon heat temperature (50, 60, and 70 °C) and the air inlet velocity (0.2, 0.4, and 0.6 m/s). The simulation results show the uniformity of temperature in the drying chamber, with the highest drying air temperature is 57.72°C, where the air temperature is influenced by the thermal temperature of the thermosiphon and the large air flow velocity. Based on the simulation conditions, the highest amount of heat needed in the drying process is 118.79 kJ/kg at temperature condition of 50°C with velocity 0.6 m/s and the lowest is 117.41 kJ/kg.