Vane detachment in rotary compressors under low-speed conditions: Mechanisms based on mixed lubrication analysis

To ensure comfort and save energy, room air conditioners need to operate under low-temperature cooling and high-temperature heating conditions, under which the rotary compressor often runs at low rotational speeds (below approximately 20 Hz for cooling and 30 Hz for heating). This low-speed operation results in critical performance and reliability problems in practice, such as chattering noise with performance decline. A commercially available R32 rotary compressor was selected to understand and address this issue, and a mathematical model for the compressor vane was developed based on mixed lubrication. An experiment was conducted to test compressor performance in a room air conditioner and obtain the dissolution viscosity of oil sump near the vane. This experiment also enabled clarifying the impact of increasing the electronic expansion valve opening on characteristics like volumetric efficiencies and the chattering noise. Subsequently, the dynamic characteristics of the vane were analyzed, and the vane detachment mechanisms were identified by analyzing the mixed lubrication characteristics of the vane flank. Moreover, a criterion for vane detachment was proposed using a simplified model. This criterion indicates directions for further research on vane detachment and chattering noise under low-speed conditions.