Drying of turmeric (Curcuma longa) using heat pump dryer under different media

The objective of this research was to investigate the drying of turmeric (Curcuma longa) by heat pump dryer (HPD) under a closed loop system using air, nitrogen and carbon dioxide gas as drying media. The drying temperatures of 45, 50 and 55°C were applied. The velocity of drying media in the drying chamber was 0.5 m s^-1. The initial moisture content of 81% wet basis was dried down to 10% wet basis within 3, 2 and 1.5 h at drying temperatures of 45, 50 and 55°C, respectively. The drying rate was increased with drying temperatures. The drying under different media had similar drying rate at a given temperature. The coefficient of performance of the heat pump was in the range of 2.149-2.919.