Theoretical Analysis And Experimental Study Of Two-Stage Evaporation Two-Stage Compression Heat Pump Drying System

Heat pump is defined as the energy-saving device which can make the quantity of heat flow from low temperature heat source to high temperature heat source by the high-potential. The organic combination of the heat pump and the dryer compose the heat pump drying system. Compared with the conventional drying device, the heat pump drying system has a broad application prospect that depend on outstanding advantages with low energy consumption, good quality of dry products, recycled solvent, safety and environmental protection, ect. In this paper, the idea of two-stage evaporation two-stage compression heat pump drying system was proposed in order to improve the drying rate during late drying stage and reduce energy consumption. Morever, the simulation analysis and experimental research ware carried out.Chosen the R123as the heat pump working refrigerant in the simulation analysis stage, analyze the influence on the heating coefficient COPH and specific moisture extraction rate when the te1and te2for working refrigerant evaporation temperature in evaporator1and2, condensing temperature tc and two air mass flow rate ratio r(q1/q2) changing in theoretical cycle. The results showed that:when r=1,tc1=75℃,te2=20℃,te1changes from20℃to28℃, the COPH increase from3.82to4.05, the SMER increases from2.22kg/(kW-h) to2.61kg/(kW·h); when tc1=75℃, te1=30℃,te2=25℃, the value of r increases from1.5to3.5, the COPH increases from3.86to4.02, the SMER increases from2.3kg/(kW-h) to3.42kg/(kW-h), within the scope of simulation condition, the values of COPH ranges from2.40to3.01, the values of SMER ranges from0.89kg/(kW-h) to1.96kg/(kW-h).In the experiment stage, the R123was chosen as the working refrigerant, the amount of water spray equivalent to the amount of water which was removed in the drying stage, by changing the opening of the throttle valve, the electric heating power, get the corresponding experimental conditions, the law of the evaporating temperature, condensing temperature and wind speed influence the COPH and SMER studied. The results showed that:within the scope of the experimental conditions, the value of COPH changes from1.36to2.92, the value of SMER changes from1.40kg/(kW-h) to2.21kg/(kW-h), and the value of ER changes from0.45to0.59. Within the scope of the whole experimental conditions, but the actual efficiency is only40%to60%on the same conditions. However, the experimental values should be further improved.The idea of two-stage evaporation two-stage compression heat pump drying system was proposed in this paper, the results of the simulation analysis and experimental study of heat pump drying device can contribute to the further research and industrial applications, and further reduce the energy consumption.