Drying is a common unit operation in food processing facilities to lower the moisture content of foods in order to reduce water activity and prevent spoilage to improve shelf life.
Foods like fruits and vegetables are especially high in carbohydrate, vitamins and water. These compounds are easily altered in high temperature drying condition and result in food quality degradation.
In the conventional hot air dryer, air is heated up to the drying temperature using electrical heaters. In addition, the humid air leaving in the drying chamber is expelled to the ambient air, which result in the loss of both sensible and latent heat of the humid air. The relative humidity of the process air is dependent on the ambient conditions.
The use of a heat pump dehumidifier dryer enables control over the moisture content and the temperature of the process air as well as the recovery of the latent heat of vaporization of water from the exhaust stream that is otherwise lost as waste heat. Moreover, the ability of the heat pump to convert the latent heat of vapour condensation at the evaporator coil, and delivers the recovered energy as sensible heat to the drying air stream passing through the condenser coil makes them attractive.
