Rotary compressor, Oil droplet, Shadowgraphy
The lubricant oil is used to lubricate the bearings and seal the clearance between the sliding parts in the rotary compressor equipped in an air conditioning system. However, a portion of the oil is atomized and exhausted with the refrigerant flow, which reduces the system’s efficiency and reliability. In this study, a highresolution shadowgraph system is applied to a modified rotary compressor to visualize the oil droplets in its upper cavity. The oil droplet size distribution is studied statistically at different radial locations and different crankshaft’s frequencies. It is observed that more oil droplets with larger D10 and D32 are generated as the rotating frequency increases. There are fewer droplets moving toward the center of the compressor. More oil droplets in the upper cavity at higher frequency might increase the Oil Discharge Rate (ODR) if these droplets are carried into the downstream discharge tube. On the other hand, larger droplets at a higher frequency may reduce ODR since the appropriate aerodynamic design may retain these droplets in the upper cavity without moving into the discharge tube. The result can assist designers in improving the CFD analysis of compressors and ultimately reducing ODR.