Minimum Viscosity for Bearing Reliability in R290 Rotary Compressors

摘要

R290 which has been considered for use in room air conditioning systems as low global warming potential (GWP)rnrefrigerant has attracted great attention. This refrigerant is determined the lubrication performance of the slidingrnparts (especially the bearings) in rotary compressor. It is important to prevent the sliding parts from seizure and wear.rnTo ensure the bearing reliability, it is traditional for R290 compressor manufacturer to specify a minimum oil sumprntemperature difference above the saturated discharge temperature. It is a surrogate measure of minimum viscosityrnrequired to ensure adequate lubricant film thickness in bearings under the system flooding conditions. The minimumrnviscosity depends on the bearing geometry, the load and the speed. This paper describes a method for specifying thernminimum safe viscosity of the high-side R290 rotary compressors based on lubricant film thickness calculations.