Numerical Simulation And Performance Study Of Heat Pump Dryers With Heat Recovery Exchanger

In the1970s later and1980s early, heat pump technique that is high efficient and energysaving had been gradually used in the drying filed. Thus the heat pump drying techniquecame into being, now it is increasingly attached importance to because of its individualdrying theory, high efficient and energy saving, high thermal efficiency, rapiddehumidification and good drying quality.According to the theory of heat pump drying, an air source heat pump dryer (HPD) withheat recovery exchanger for drying the air-condition unit of train is given and designed,especially the drying room is designed and researched in detail. First, in the drying room, airsupply is60℃/27%, air return is48℃/55%, air rate is1500m3/h, the moisture extraction rate(MER) is10kg/h. Second, axial fan used in the surface drying and inductive fan used in thepartial drying are planned, which impose the air circular convection and improve the dryingrate. Additionally, utilizing the software FLUENT simulates the air circular flow of dryingroom, the simulation result is that the surface velocity of air-condition unit is greater than5m/s, which has already fulfilled the design request.Making use of the meteorological database METEONORM generates and analyzes thetypical meteorological year (TMY2) of Wuhan, the result is: the maximum temperature is37.1℃(July), the minimum temperature is-3.8℃(January),the annual average is17.6℃; thehighest relative humidity is100%and the lowest is32%,the annual mean is72%. ThereforeWuhan belongs to the typical climatic area where winter is cold and summer is hot.The mathematical models of main components are set up, with the platform ofTRNSYS, method and process how the simulation modeling of air source HPD with heatrecovery exchanger is found are analyzed in detail, and applying the modeling analyses andstudies HPD. In the yearly simulation, the change of the operation parameters, the moistureextraction rate (MER), energy consumption of heat pump, COP and the specific moisture extraction rate (SMER) of HPD with heat recovery exchanger is analyzed, and system withreheater and without reheater is provided a contrast: when having a heat recovery exchanger,energy consumption of heat pump, total heating rate and heat transfer rate of reheater arehigh in the summer, low in the winter, and auxiliary heating rate is little in the summer, toomuch in the winter. Comparing with no reheater, the HPD with reheater has a little higherenergy consumption, but its auxiliary heating rate decreases on average by73.8%, COPincreases by6%, the specific moisture extraction rate (SMER) has a average increase by79.2%, accordingly energy saving is very much in evidence.In conclusion, the air source heat pump dryer with reheater is fit for drying ofair-condition unit, which is high efficient and evident energy saving, especially is betterpopularized in the south areas of Changkiang.