室外换热器可变流路设计及试验分析

The design and experimental analyses on variable refrigerant flow path of outdoor unit

为了确定制冷与制热模式下换热器的最优流路,建立了空调室外机的蒸发器/冷凝器仿真模型,并将换热器仿真模型耦合入系统仿真中,分析了不同流路对系统换热量及系统性能的影响,以确定换热器在制冷与制热模式下所对应的最优流路。结果表明,当分路数在5~20范围内变化时,在制冷模式下整机能力及性能随着分路数增大而减小,在制热模式下整机能力及性能随着分路数增大呈现先增加后减小的趋势;制冷模式下的优选分路数为5~7路,制热模式下的优选分路数为14~16路。在此基础上,通过单向阀与电磁阀设计了制冷/制热模式下室外机运行分路数为7路/14路的可变流路方案,试验测试结果表明,各测试工况下能效均有提升且全年能源消耗能效(APF)提高5.4%,超低温为-15℃时制热量提升6.0%,性能提升2.8%。本文研究结果可为换热器设计优化领域的研究人员提供参考。

In order to determine the optimal flow path of the heat exchanger in the refrigeration and heating modes,a simulation model of the evaporator/condenser of the outdoor unit of the air conditioner was established,and the heat exchanger simulation model was coupled into the system simulation to analyze the impact of different flow paths on the heat transfer and system performance so as to determine the optimal flow path of the heat exchanger corresponding to the refrigeration and heating modes.The results show that the capacity and performance of the entire system decreases as the number of paths varies in the range of 5 to 20 in cooling mode,while in heating mode,the capacity and performance shows an increasing trend at first and then a decreasing trend as the number of paths increases.The optimal number of paths in cooling mode was 5~7,and in heating mode is 14~16.Based on this,a variable flow path scheme with 7/14 flow paths for outdoor unit operation in cooling/heating mode through check valves and solenoid valves.Experimental results show that the system performance is improved and the annual performance factor(APF)is increased by 5.4%under various test conditions,and the heating capacity is increased by 6.0%at an ultra-low temperature of-15℃and the system performance is increased by 2.8%.The research results can provide reference for researchers in the field of heat exchanger design optimization.