节流元件中电子膨胀阀控制制冷剂流量最为精准。对热泵热水器中电子膨胀阀的节流特性进行试验研究，结果表明：系统制热性能随阀开度的增大而先增大后减小，电子膨胀阀有最佳调节区间；制冷剂充注量和水流量均影响电子膨胀阀节流特性，使最佳调节区间发生偏离，充注量增大将降低电子膨胀阀调节精度，水流量增大需增大制冷剂流量与之匹配；当充注量在最佳值附近发生偏离时，可调节阀开度和水流量等条件进行修正，以使充注量返回最佳值。

In throttling elements,the electronic expansion valve is the most accurate in controlling refrigerant flow.In this paper,the throttling characteristic of electronic expansion valve in heat pump water heater is studied.The results show that heating performance of system increases first and then decreases with the increase in the valve opening,and electronic expansion valve has best regulation interval.Moreover,due to the influence of refrigerant charge and water flow rate on throttling characteristic of electronic expansion valve,the best regulation interval will deviate.The increase of charge will decrease regulating accuracy of electronic expansion valve.Large water flow rate requires large refrigerant flow rate.Furthermore,when charge deviates from optimum value,valve opening and water flow rate can be adjusted to ensure the charge returns back to the optimum.

TK124

上海市动力工程多相流动与传热重点实验室(1N-15-301-101)；2015年住房和城乡建设部科学技术计划项目(2015-K7-026)；2016嘉兴市科技计划项目(2016AY13019)