HIGH-TEMPERATURE HEAT PUMP-ASSISTED SOFTWOOD DRYER: SIZING AND CONTROL REQUIREMENTS & ENERGY PERFORMANCE

摘要

Drying of solid, porous and hygroscopic materials is a complex and energy intensive process. About 85%of existing industrial dryers are convective dryers using hot air as a drying medium; they may consume upto 25% of the national industrial energy used in most of developed countries. Among other methods forreducing global energy consumption (electrical and fossil) in the drying industry there are heat pumpdryers. First, this paper succinctly describes a high-temperature heat pump-assisted industrial-scalesoftwood dryer located in the Canadian cold climate, as well as the drying process, heat pump sizingprinciples and dryer energy estimation. Second, some control requirements aimed at matching the thermalcapacities of the dryer-heat pump coupled system are proposed in order to improve system reliability andhelp increase the number of successful industrial implementations. Finally, several improvedthermodynamic parameters and drying energy performance results obtained after implementation of theproposed control measures are provided.