ANALYSIS OF ENERGY-CONSUMPTION IN HEAT-PUMP AND CONVENTIONAL DRIERS

This paper compares energy consumption in heat pump driers and recircu lating driers. The purpose of the analysis is to establish more genera l guidelines than those currently available in order to determine whic h drier configuration is a better choice at any given operating condit ions. The comparison is based on computer models of the heat pump and recirculating driers. The models predict energy consumption figures fo r both driers operating at identical conditions (therefore extracting the same amount of water from the drying material). The results are sh own as the mass of water evaporated per unit of energy input (the spec ific moisture extraction rate (SMER)) for both drier configurations. T hese values, as well as the ratio between these, are plotted in charts that show all the possible operating conditions, to enable easy compa rison. The comparison presented here is based on energy consumption fi gures only, and therefore has the advantage of being independent of lo cal conditions (such as economics, electricity generating efficiencies or relative values of different fuels) that are subjected to change. On the other hand, the SMER values presented can be easily modified to include the effect of local conditions in the drier selection process .