The influence of POE and PVE lubricant blends within hermetic refrigerating compressors operating with HFC-134a refrigerant

Hydrofluorocarbons are alternative refrigerants receiving attention for use in domestic refrigerating systems. New synthetic lubricants are required with these working fluids to ensure lubricant suitability. The objective of this experimental investigation is to compare the tribological performance of the newly developed polyvinylether (PVE) synthetic lubricant to its polyol ester (POE) counter-part. Experimental setups were varied using actual hermetically sealed refrigerating compressors. This investigation included an evaluation of the conforming contact between the small end of the connecting rod and the gudgeon pin. This was done in conjunction with observations of the large end of the connecting rod as well as the compressor valve plates. Observations were carried out using light microscopy, scanning electron microscopy (SEM), energy dispersive X-ray (EDX) micro-analysis and X-ray photoelectron spectroscopy (XPS) analysis. The extent of the surface damage observed varied with the type of lubricant and the operating pressures.