空气源热泵系统湿压缩与电子膨胀阀调控方式的研究

Study on wet compression and control mode of electronic expansion valve of air source heat pump system

针对空气源热泵吸气带液问题,通过调节电子膨胀阀开度改变压缩机吸气口制冷剂状态,研究了四种不同调控工况对系统性能和参数的影响,分析不同调控工况下系统性能的变化。实验结果表明:较大的电子膨胀阀开度可提高蒸发压力和制冷剂质量流量,从而改善系统性能,但这不是湿压缩所产生的影响,相反后期大量的吸气带液会导致系统性能降低;吸气带液可以有效降低压缩机排气温度,同时也会使单位制热量和比功降低;在实际运行过程中,应采取定过热度控制方法,且过热度应尽量小,但要避免压缩机吸气带液。

Regarding the problem of inhalation with droplets in air source heat pump system,the state of refrigerant at compressor inlet was changed by adjusting the opening of the electronic expansion valve.Influences of four different control modes on system performance and parameters wereanalyzed.Experimental results showed that increasing electronic expansion valve opening was favorable to lifting evaporation pressure and increasing refrigerant mass flow,and furthermore improving the system performance.However,a large amount of liquid refrigerant inhalation in the later stage will lead to system performance degradation.In addition,inhalation with droplets can effectively reduce the compressor discharge temperature,and also heating capacity and specific work.In practical operation process,the degree of superheat should be controlled as small as possible,while the compression with liquid must be avoided.