Oil sump temperature in hermetic compressors for heat pump applications

The oil temperature in the compressor sump is an important parameter describing the performance of a refrigeration compressor. Its estimation is necessary for evaluation of the lubricant-refrigerant mixture composition and its properties. In contrast, this temperature is not normally measured in compressor performance tests and is unlikely reported by the manufacturers or in the technical literature. s paper, a set of tests measuring the oil sump temperature for hermetic reciprocating and scroll compressors in a wide range of working conditions is presented. From these results and after a theoretical analysis of the factors having influence on this parameter, a correlation for the oil temperature as a function of compressor inlet and outlet conditions is presented. This correlation allows to estimate the oil sump temperature for scroll and hermetic reciprocating compressors as a function of operation conditions with an error lower than 4 K degree for most of the cases.