Piston ring–cylinder liner lubrication analysis in a CO₂ refrigeration reciprocating compressor

摘要

A simulation model is developed for the piston ring–cylinder liner lubrication problem in a CO₂ refrigeration reciprocating compressor. Patir and Cheng’s modified Reynolds equation including pressure flow factors, shear flow factors, and shear stress factors is used to consider the effect of surface roughness on lubrication. The piston ring is assumed to be fully flooded at the leading edge, and both the cavitation case and fully flooded case are considered at the trailing edge. Modified Reynolds boundary condition is employed. The simulation results show that, the minimum oil film thickness has a maximum magnitude in the middle stroke region for downward stroke and upward stroke. In the vicinity of the dead centres, the magnitude of the friction force is much higher than that in the middle stroke region. The oil film pressure distribution along the piston ring thickness at different specified crank angles is indicated. The effects of ring thickness, crown height on minimum oil film thickness, and friction force are also investigated.