多联式热泵空调用电子膨胀阀进出口流向控制对节流噪声影响的实验研究

Experimental Study on the Effects of Refrigerant Inlet and Outlet Flow Directions on the Throttling Noise of Electronic Expansion Valve in Multi-split Heat Pump Air Conditioners

多联机热泵空调用电子膨胀阀因具有进出口管相互垂直的结构特性,使制冷剂具有以垂直阀针轴线方向和以平行阀针轴线方向进入电子膨胀阀两种流向形式,制冷剂在这两种流向型式下节流时产生的节流噪声具有明显差异,需要明确进出口流向控制对节流噪声的影响。设计并搭建了可对流经电子膨胀阀的制冷剂进行状态调控和流型观测且可对节流噪声的声压级进行测量的实验装置,获得了不同制冷剂流量和干度工况下制冷剂流向对节流噪声的影响规律。研究表明:制冷剂从与阀针轴线方向垂直的进口管流入时,节流噪声主要表现为制冷剂节流空化时产生的空泡溃灭噪声,声压级范围较低;制冷剂从与阀针轴线方向平行的进口管流入时,节流噪声表现为空泡溃灭与阀针振动相互耦合的噪声,声压级范围较高;在实验中这两种流向下节流噪声的声压级范围分别为47.1~57.1 dB及61.9~67.7 dB。通过对空调系统的制冷剂流向进行优化设计,保证制冷剂始终从与阀针轴线方向平行的进口管流入电子膨胀阀,可降低多联机热泵空调系统在运行过程中的噪声水平。

The electronic expansion valve(EEV)used in multisplit heat pump air conditioners has the structural characteristics of import and export tubes perpendicular to each other,such that the refrigerant has two forms of flow into the EEV,that is,in the direction perpendicular to the valve needle axis and the direction parallel to the valve needle axis.The sound pressure level of the throttling noise exhibits evident differences in these two directions,and it is necessary to clarify the impact of the flow direction on the throttling noise.The purpose of this study is to design and build an experimental rig that can regulate the refrigerant state flowing into and out of the valve,observe the refrigerant flow pattern,and measure the sound pressure level of the throttling noise,thus obtaining the effects of the refrigerant flow directions on the throttling noise under different refrigerant flow rates and vapor qualities.The results show that when the refrigerant flows from the inlet pipe perpendicular to the direction of the valve needle axis,the throttling noise is mainly the collapse noise of vapor bubbles generated by the refrigerant throttling cavitation,and the overall noise sound pressure level is low.When the refrigerant flows from the inlet pipe parallel to the direction of the valve needle axis,the throttling noise is a combination of the noise due to bubble collapse and the noise due to vibrations of the valve needle,and the overall noise sound pressure level is high.In this experiment,the sound pressure levels of the throttling noise in these two flow directions range from 47.1 dB to 57.1 dB and 61.9 dB to 67.7 dB,respectively.The throttling noise in the air-conditioning system can be effectively reduced by optimizing the design of the refrigerant flow direction of the air-conditioning system and ensuring that the refrigerant always flows into the EEV from the inlet pipe parallel to the direction of the valve needle axis.