Analysis of energy consumption in heat pump and conventional driers

This paper compares energy consumptions in ehat pump driers and recirculating driers. The purpose of the analysis is to establish more general guidelines than those available in order to determine which drier configuration is a better choice at any given operating conditions. The comparison is based on computer models of the heat pump and recirculating driers. The models predict energy consumption figures for both driers operating at identical conditions (therefore extracting the same amount of water from the drying material). The results are shown as the mass of water evaporated per unit of energy input (the specific moisture extraction rate (SMER)) for both drier configurations. These values, as well as the ratio between these, are plotted in charts that show all the possible operating conditions, to enable easy comparison. The comparison presented here is based on energy consumption figures only, and therefore has the advantage of being independent of local 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.