Numerical and experimental study on cavitation and noise characteristics of electronic expansion valve

This paper systematically elaborates on the turbulence model, multiphase-flow model, and noise model. The turbulence model is adept at accurately characterizing the flow behavior of complex fluids. In contrast, the multiphase - flow model, in conjunction with the noise model, can precisely depict the phase-change phenomena and the noise generated as a consequence of pressure fluctuations during the fluid-flow process. An electronic expansion valve, functioning as a pivotal control valve in an air-conditioning system, assumes the critical responsibilities of regulating the flow rate and effectuating throttling expansion. Nevertheless, when the refrigerant within the electronic expansion valve traverses the vicinity of the valve needle, a prevalent phenomenon transpires: the abrupt alteration in the cross-sectional area of the flow passage engenders a change in fluid pressure, thereby giving rise to cavitation. This cavitation phenomenon represents the primary causative factor for noise generation in this type of valve. In this study, a comprehensive investigation into the flow of refrigerant within the electronic expansion valve is conducted by means of both numerical simulation and experimental approaches. For the first time, the combined effect of the spring force exerted by the valve needle of the electronic expansion valve and the fluid force of the refrigerant is meticulously considered. During the numerical-simulation process, the user-defined function (UDF) is skillfully employed to precisely describe this combined force. To mitigate the cavitation-induced noise of the electronic expansion valve, a novel seated-dune-guide-vane structure design is implemented for the valve. Under identical operating conditions, the maximum noise level of the valve incorporating the seated-dune-guide-vane structure is reduced by 10 dB in comparison to that of the original valve structure. These research findings unequivocally demonstrate that optimizing the valve-structure design through the utilization of a numerical-simulation method integrated with multiphase-flow and noise models can effectively abate the noise generated by the electronic expansion valve. This optimization not only significantly enhances the operating efficiency of the air-conditioning system but also substantially improves the user experience.