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 w ake of international agreements aimed at developing more environmentally ac ceptable refrigerants. An evaluation of the tribological characteristics re lating to the conforming contact between the die-cast aluminium alloy conne cting rod and the: hardened steel gudgeon pin of a reciprocating compressor is presented. An experimental investigation was carried out on liquid/vapo ur refrigeration systems. Hermetic refrigerating compressors, working in an HFC-134a environment and at high compression ratios, were adopted. Three s ynthetic lubricants, characterised by viscosity, were used. Results indicat ed extensive surface damage, observed at the interfaces, depending on the v iscosity of the lubricant/refrigerant combination used. Wear mechanisms wer e studied using scanning electron microscopy (SEM), energy dispersive X-ray (EDX) analysis and light microscopy analysis. Evidence of adhesive wear an d lubricant decomposition were observed. The significance of this study is to assist industry and related research work in the optimal design and sele ction of working fluid viscosities to be used in domestic refrigerating sys tems working in an HFC-134a environment. (C) 1999 Elsevier Science S.A. All rights reserved.