Research on the characteristics of two-phase flow-induced noise in the cavitation dynamics of electronic expansion valves

Abstract

Electronic expansion valves are widely used in refrigeration systems. However, the two-phase flow-induced noise is often produced during operation. In this paper, the two-phase flow-induced noise characteristics of electronic expansion valves are investigated by means of a combination of numerical calculations and experimental studies. The numerical results show that the noise distribution in the flow field is closely related to the valve opening. As the valve opening increases, the noise in the flow field begins to develop in the downstream region. The experimental results showed a gradual increase in the refrigerant flow rate of the experimental system as the valve opening was increased from 60 to 200 pulses (tested at 10-pulse intervals). The flow-induced noise increases first and then decreases and then increases. With the increase in valve opening, the cavitation phenomenon after valve throttling becomes more and more serious. By processing the noise signal, it is found that the flow-induced noise is distributed in wide frequency. When the valve opening is 60–100 pulse, the noise is mainly concentrated in 10–20 kHz. When the valve opening is 110–150 pulses, the noise concentrated in the high band gradually spreads to the low band. When the valve opening is 160–200 pulses, the noise at low frequency and high frequency increases significantly with the increase in valve opening. After adding a groove structure on the valve core, the noise of the electronic expansion valve decreased by 1.75 dB.