Study on the oil supply characteristics of R290 rotary compressors under high-speed conditions.

To minimize the charge of flammable refrigerants in air conditioning systems, there is an increasing trend towards the miniaturization and high-speed operation of rotary compressors. However, the oil supply behavior of rotary compressors under high-speed conditions remains unclear. This study conducts a numerical investigation into the oil supply characteristics of high back-pressure R290 rotary compressors at elevated rotational speeds. A comprehensive simulation model of the oil supply system was developed, integrating both stationary and rotating regions and employing the volume of fluid (VOF) method. Experimental validation confirmed a deviation of less than 4 % between the simulated and measured results. The study systematically examines the effects of factors such as rotational speed, refrigerant type, and gas hole direction on the oil supply performance under high-speed conditions. Results revealed that with increasing rotational speed, the oil supply through the spiral groove increased linearly, and the oil film in the central hole of the crankshaft became thinner. Additionally, compressors using R290 exhibited a lower oil supply rate compared with those utilizing R134a, primarily due to the lower gas density of R290. Crankshafts featuring radial gas holes demonstrated superior oil supply efficiency compared with those with axial outlets. This study offers valuable theoretical insights for optimizing oil supply systems in high-speed rotary compressors, contributing to the advancement of their design and performance.