Thermal characteristics of heat pump dryer for ginger drying

We discuss the drying performance and energy consumption of a closed system heat pump dryer for ginger drying at 50 °C within 200 minutes using air and nitrogen as the drying medium. The fresh ginger at moisture content of 777 was dried by air and nitrogen down to 132 and 89% dry basis. The gained heat at the internal condenser was 15.4 and 20.5 MJ, and rejected heat at evaporator was 18.6 and 22.9 MJ for air and nitrogen cycles, respectively. Heater provided 62.93 and 65.60% total input energy of refrigerant cycle while heat gained at external condenser were 37.92 and 28.79% output for air and nitrogen drying respectively. Air drying required total input energy of 11.6 compared to nitrogen of 12.5 MJ. Specific moisture extraction rate of ginger drying in air was 0.06, while nitrogen was 0.07 kg water/MJ. Specific energy consumption of air drying was 16.67 while nitrogen was 14.29 MJ/kg water.