Specific Energy Consumption of Heat Pump Drying System
The study developed a heat pump dehumidifier (HPD) dryer prototype incorporating an external condenser. The main feature of the HDP dryer prototype is its capability to adjust the drying air temperature and moisture content depending on the drying requirements of a particular product. It consisted of 90cm x 56cm x 61cm (length, width & height respectively) drying chamber and 4 layers of tray system and each layer has 1 tray. The tray has a dimension of 46cm length and 37cm width respectively. A 1.5 hp (1.12kW) piston compressor. Mango was used in the experiment as a test sample product. Three test sample loads were experimented, namely: 170g, 340g and 510g which were dried in the HPD dryer system for a drying air temperature of 40 oC and drying air velocity of 0.7 m/s. The specific moisture evaporation rate (SMER); and the specific energy consumption (Ekg) for both wet and dry products were calculated using the measured data. The amount of moisture evaporated to reach the final moisture content of 15% wet basis was calculated and the energy consumed was determined in kilowatt-hour meter from the measured value. The results revealed that there is reduction of energy consumption as product load is increased.