Influence of Thermodynamic Process Parameters on the Acoustic Properties of Electric Refrigerant Scroll Compressors

Abstract

With the ongoing electrification of vehicles, the acoustic properties of the vehicle's interior are increasingly affected by auxiliary units. In electric vehicles, the battery and the electric motors must be cooled in addition to the passenger cell. Therefore, larger A/C compressors are needed, which increase sound radiation and vibration excitation. The compressor is the central sound source in the refrigeration circuit, on the one hand through direct airborne sound radiation, on the other hand it causes acoustic excitation of other refrigeration circuit components via pressure pulsations and vibration transmission. To characterize the acoustic properties of refrigerant scroll compressors, a test rig was developed that allows an isolated observation of the acoustic properties of refrigerant compressors in an anechoic chamber. This paper investigates the influence of thermodynamic process variables on compressor acoustics and shows that increasing speed and compression ratio lead to greater sound radiation. The sound spectra of fluid, structure and airborne noise are dominated by speed-dependent, tonal components. The findings provide insights into the physical relationship between thermodynamic and acoustic parameters and enable the identification of a low noise operating range.