Study of Kaffir Lime Leaves Drying by Using the Heat Pump

Abstract

This research aimed to study the drying of kaffir lime leaves using a heat pump. The heat pump dryer was a vapor compression type using R-134a refrigerant as the working fluid. The drying chamber had a volume of 0.12 m3 and 7 trays, capacity 7 kg. of fresh kaffir lime leaves at a time. The average speed of the vapor compressor was 894 rpm. The initial average moisture content of the kaffir lime leaves was 62.28% (wet basis), and the final drying resulted in a moisture content of no more than 10% (wet basis). Drying tests of kaffir lime leaves at temperatures of 40, 45, 50, and 550 C, showed that 550 C for 6 hours was the most suitable temperature and drying time, as it resulted in the shortest drying time and the desired color and aroma of the dried product. The average hot air velocity was controlled at 1.28 m/s. The coefficient of performance of the heat pump system (COP) was 3.89, payback period of 21 drying cycles.