结霜工况下空气源热泵-冷柜双联机性能实验研究

Experimental Study on Performance of Combined Air-source Heat Pump and Freezer under Frosting Condition

空气源热泵-冷柜双联机将热泵系统部分制冷剂用于对冷柜制冷系统进行机械过冷,可提高系统整体性能。本文将空气源热泵室外机与冷柜冷凝器设计成一体式换热器,在冬季工况下可利用冷柜制冷系统的冷凝热延缓空气源热泵室外机结霜。实验研究了结霜工况下空气源热泵-冷柜双联机性能,将热泵-冷柜联合运行工况下的性能与热泵单独运行工况下的性能进行了对比,并分析了不同冷流比条件下热泵系统、冷柜系统性能及热泵室外换热器表面结霜性能。实验结果表明:在室外换热器严重结霜工况下,相比于空气源热泵单独运行,双联机联合运行使结霜周期延长为原来的2.17倍,热泵系统平均制热量及平均COP分别提高了约5%及4.8%。随着冷流比增大,冷柜系统平均制冷量和平均COP均增大。而空气源热泵在冷流比为0~12%范围内,结霜周期、平均制热量及平均COP均变化较小,当冷流比大于12%时,随着冷流比增大,结霜周期缩短,平均制热量及平均COP呈下降趋势。

A part of the refrigerant of the air-source heat pump(ASHP)system is used for mechanical subcooling of the freezer in the combined air-source heat pump and freezer system.This can improve the performance of the system.In this paper,the outdoor heat exchanger of the ASHP system and condenser of the freezer was designed as an integrated heat exchanger,which can retard the frost formation and growth in winter.The performance of the combined ASHP-freezer under frosting condition was studied experimentally,and the performance of ASHP system and freezer under combined operating conditions was compared with that under separated operating conditions.The performance of the combined system and the frosting characteristics on the outdoor heat exchanger were analyzed under different cooling mass flow ratios.The experimental results indicated that the frosting period of the integrated outdoor heat exchanger under combined working conditions of ASHP-freezer is prolonged as 2.17 times as that under separated operating conditions,when the outdoor heat exchanger is severely frosted.The average heating capacity and average COP of the ASHP system under combined working condition were increased by approximately 5%and 4.8%,respectively,when compared with that under separated operating conditions.The average refrigerating capacity and average COP of the freezer increased as the cooling mass flow ratio increased.With respect to the cooling mass flow ratio in the range of 0-12%,the frosting period,average heating capacity,and average COP of the ASHP system slightly changed as the cooling mass flow ratio increased.Conversely,in range exceeding 12%of cooling mass flow ratio,the frosting period was reduced as the cooling mass flow ratio increased,and the average heating capacity and average COP exhibited a downward trend.