The influence of lubricant viscosity on the wear of hermetic compressor components in HFC-134a environments

Hydrofluorocarbons (HFCs) are transitional refrigerants being used in the wake of international agreements aimed at developing more environmentally acceptable refrigerants. An evaluation of the tribological characteristics relating to the conforming contact between the die-cast aluminium alloy connecting rod and the: hardened steel gudgeon pin of a reciprocating compressor is presented. An experimental investigation was carried out on liquid/vapour refrigeration systems. Hermetic refrigerating compressors, working in an HFC-134a environment and at high compression ratios, were adopted. Three synthetic lubricants, characterised by viscosity, were used. Results indicated extensive surface damage, observed at the interfaces, depending on the viscosity of the lubricant/refrigerant combination used. Wear mechanisms were studied using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and light microscopy analysis. Evidence of adhesive wear and lubricant decomposition were observed. The significance of this study is to assist industry and related research work in the optimal design and selection of working fluid viscosities to be used in domestic refrigerating systems working in an HFC-134a environment. (C) 1999 Elsevier Science S.A. All rights reserved.