支路数对热泵空调中冷凝和蒸发两用换热器性能的影响

Effect of Circuit Number on the Indoor Coil Serving as Both Condenser and Evaporator in Heat Pump

在空气的进口状态和流量、换热器的几何结构尺寸、管路排布方式等相同时,研究了支路数对蒸发和冷凝两用换热器流动与传热性能的影响规律．结果表明:随支路数增多,空气与制冷剂间的传热温差会增大,但总传热系数却会变小;室内换热器作蒸发器时,换热量先升后降,最小值比最大值小23.2%,存在使换热量最大的最佳支路数,在支路数小于或大于最佳支路数时,换热量的主导因素分别为传热温差与总传热系数;室内换热器作冷凝器时,换热量随支路数增多单调递减,最小值比最大值小40.55%,总传热系数始终是制约换热量的主导因素．因此,为协调并同时提高制冷、制热循环的效率,需要优化热泵系统中换热器的支路数．

The effect of the circuit number on the indoor coil in a split-type air-source heat pump is investigated numerically by EVAP-COND 2. 0 version simulation package of American NIST. The indoor coil serves as an evaporator in a cooling cycle and as a condenser in a heating cycle. The simulation demonstrates that the air-and-refrigerant temperature difference increases with the circuit number, but the overall heat transfer coefficient drops. The evaporator capacity rises firstly, and then drops with the circuit number and achieves the maximum in the optimum circuit number. The minimum evaporator capacity gets less than the maximum by 23. 2%. The air-and-refrigerant temperature difference and the overall heat transfer coefficient become the dominant factor governing the evaporator capacity, respectively behind and beyond the optimum circuit number. The condenser capacity always decreases with the circuit number and the overall heat transfer coefficient acts as the dominant factor. The minimum condenser capacity is less than the maximum by 40.5 %. These results demonstrate that the indoor coil in a heat pump is endowed with an optimal circuit number to heighten the efficiencies and capacity in heating and cooling cycles simultaneously.