Effect of lubricant on spray evaporation heat transfer performance of R-134a and R-22 in tube bundles

This study evaluates the effects of lubricant on spray evaporation heat transfer performance. Tests were conducted with refrigerant R-134a and triangular-pitch tube bundles made from enhanced-condensation, enhanced-boiling, low-finned, and plain-surface tubes. A 340-SUS polyol-ester oil was used for the R-134a testing because this lubricant is being integrated into industry for use with this refrigerant. Spray evaporation heat transfer tests were performed at oil concentrations of 1.0% and 2.5% by mass fraction of the total refrigerant/lubricant mixture. Two refrigerant supply rates were used for the R-134a testing so that the effects of film-feed supply rate could be interpreted from the data. Limited testing was also conducted on R-22 with an enhanced boiling surface and a plain-surface bundle. A 300-SUS alkyl-benzene oil was used for the R-22 refrigerant/lubricant mixture tests.

Effect of lubricant on spray evaporation heat transfer performance of R-134a and R-22 in tube bundles Academic Article