使用电子膨胀阀的空气源热泵热水器的实验研究与优化

Optimization and Experimental Study on Air Source Heat Pump Water Heater with Electronic Expansion Valve

为充分利用电子膨胀阀调节灵活的特性,对空气源热泵热水器在定阀开度和定过热度下的系统性能进行对比实验,并提出了电子膨胀阀的排气温度控制法。实验结果表明：定阀开度下运行易发生吸气带液现象,吸气带液量的大小对系统性能的影响较大,但可由排气温度加以判断,适当增大阀开度可提升平均制热效率（COPa）并降低排气温度;与定阀开度相比,定过热度下运行时COPa普遍较高,排气温度高,但改变定过热度对COPa的影响较小,这为过热度的简单控制提供了依据;提出的排气温度控制法以排气温度判断吸气带液量大小,对过热度进行简单控制,满足了大制冷剂流量和小过热度的制热要求,试验测试中COPa提升8.24%,排气温度降低7.16%,系统性能达到了预期的优化效果。

In order to make full use of EEV flexible characteristic, the performance of air source heat pump water heater under fixed valve opening and fixed superheat is studied and an exhaust temperature control method of EEV is proposed. The results show that compressor is easy to suck air with liquid when system is running with fixed valve opening. The amount of liquid suction has a great effect on system performance. The liquid volume can be determined by exhaust temperature. Increasing the valve opening properly can increase COPa and reduce exhaust temperature. Moreover, compared with fixed valve open- ing, COPa at fixed superheat is generally higher, with high exhaust temperature, but the impact on COPa is smaller as the fixed sumperheat is changed, supporting the concept of a simple control for superheat. Finally, the exhaust temperature control method of EEV can be used to determine the volume of liquid and simply control superheat, to meeting the requirements of large refrigerant flow rate and small superheat for the system. Experimental tests show that COPa is increased by 8.24%. and exhaust temperature is decreased by 7.16%. The system performance has achieved the expected optimization effect.