Chilli and Garlic Drying by Using Waste Heat Recovery from Geothermal Power Plant

Abstract

The objective of this research is to design a dryer that uses waste heat from geothermal power plant. The dryer was built at the geothermal power plant in Fang district, Chiang-Mai province, Thailand. The geothermal hot water, about 80?, circulates through a cross-flow heat exchanger of 100 mm width, 500 mm length and 300 mm height. A 2 hp (1420 rpm) motor is used for driving the dryer blower. The outgoing air from heat exchanger with constant flow rate (1 kg/s) is introduced into the drying chamber of 10.5 m³ volume. The experiments were made for chilli (450 kg) and garlic (220 kg).

            For Chilli (75% wb to13% wb) the required air temperature is about 70? whereas for garlic (75% wb to 55 wb), 50? is needed. The corresponding drying time and mass flow rate of hot water are about 46 hours/1 kg.s¹ for chilli and 94 hours/0.04 kg.s¹ for garlic.

            Thus, two sources of energy which are thermal energy from geothermal power plant and electricity from blower were used. The total energy consumed was 13.3 MJ or 40.94 MJ/kg H₂O evap. for chilli 1.5 MJ or 15.71 MJ/kg H₂O evap. for garlic. The corresponding part of energy consumed from waste heat geothermal plant is 96.5% for chilli and 38.0% for garlic drying. Assessment of economic feasibility is also presented.