Influence of geometric parameters on ejector acoustics and efficiency in ejector refrigeration system

Abstract

Ejectors are extensively utilized in Ejector Refrigeration System (ERS), serving as essential elements for process propulsion and vapor recirculation. However, their operation produces substantial aerodynamic noise, which adversely affects the surrounding environment and human health. Consequently, an investigation was conducted into the correlation between aerodynamic noise and the ejector's performance, based on the geometric configuration of the ejector. Additionally, the flow field of the ejector was analyzed. Nine types of ejectors with different area ratios (AR) and nozzle exit positions (NXP) were established, and the simulation results showed that the aerodynamic noise was positively correlated with the turbulence intensity. The higher the turbulence intensity, the higher the sound power level of the noise. As the AR increased from 5.8 to 11.4, turbulence intensity gradually decreased. An increase in AR by 1.4 resulted in a reduction of aerodynamic noise by 2–3 dB, while the entrainment ratio (ER) initially increased and then decreased. With an increase in the primary flow pressure, the optimal AR moves backward. The change in NXP has a negligible effect on turbulence intensity and ejector noise but significantly impacts ER. Overall, 9 different AR and NXP ejectors were 3D-printed and tested. The far-field noise data of the experimental ejector exhibited the same trend as the simulated noise data, which verified the simulation results. The ejector's optimal structure was discussed based on its ability to maintain relatively higher ER and lower noise levels amid pressure fluctuations.