Specific energy consumption in microwave drying of garlic cloves

Abstract

The convective and microwave-convective drying of garlic cloves was carried out in a laboratory scale microwave dryer, which was developed for this purpose. The specific energy consumption involved in the two drying processes was estimated from the energy supplied to the various components of the dryer during the drying period. The specific energy consumption was computed by dividing the total energy supplied by amount of water removed during the drying process. The specific energy consumption in convective drying of garlic cloves at 70 °C temperature and 1.0 m/s air velocity was estimated as 85.45 MJ/kg of water evaporated. The increase in air velocity increased the energy consumption. The specific energy consumption at 40 W of microwave power output, 70 °C air temperature and 1.0 m/s air velocity was 26.32 MJ/kg of water removed, resulting in about a 70% energy saving as compared to convective drying processes. The drying time increased with increase in air velocity in microwave-convective drying process; a trend reverse to what was observed in convective drying process of garlic cloves.