Performance of a heat-pump assisted dryer

Abstract

We present a simple mathematical model of a heat-pump-assisted dryer developed from psychrometric processes. A term 'contact factor' is used in the theoretical model to characterize the drying chamber. The experimental data of the drying rates of different types of products are used to predict the values of the contact factor of the dryers. We examine the effect of various parameters such as the contact factor, air inlet conditions, and the moisture removal rate on the performance of the heat-pump-assisted dryer. It has been shown that the non dimensional contact factor of a dryer is insensitive to dryer air inlet temperature. Finally, a performance chart to guide the selection of the heat-pump dryer components is proposed.