CFD Study on Effects of Unilateral Axial Clearance on Inner Pressure Distribution and Performance of a CO2 Scroll Compressor

Abstract As the core component of CO2 heat pump air conditioning systems for electric vehicles, the performance of scroll compressors directly affects system energy efficiency and vehicle driving range. This study, for the first time, combines computational fluid dynamics (CFD) simulations with a one-dimensional dynamic model to systematically analyze the impact of unilateral axial clearance on the pressure characteristics of working chambers and the tangential gas force in CO2 scroll compressors. The research reveals that inter-stage leakage induced by unilateral axial clearance disrupts pressure uniformity in symmetrical working chambers, resulting in a maximum pressure difference exceeding 2 MPa. Dynamic simulations further demonstrate that positioning the unilateral axial clearance at the top of the orbiting scroll significantly improves compressor performance: the peak pressure difference in symmetrical working chambers is reduced by 8.09%, the maximum tangential gas force decreases by 818.29 N, and average power consumption drops by 30.43%. Additionally, when the unilateral axial clearance is located at the top of the orbiting scroll, it facilitates early leakage of high-pressure gas from the middle discharge ports through indirect flow paths, effectively suppressing pressure fluctuations. Therefore, optimizing the manufacturing tolerance matching between the orbiting and fixed scrolls to ensure the unilateral axial clearance is positioned at the top of the orbiting scroll represents a critical approach for enhancing the performance of CO2 scroll compressors.