Migration of lubricating oil from the compressor crankcase into other components of a vapor compression refrigerating system, such as a condenser, is a common occurrence. The presence of oil during the condensation of a refrigerant vapor will in general have some effects on the rate of heat transfer.

The objective of the ASHRAE RP-378 research project is to experimentally investigate the effects of selected refrigerant-oil mixtures on condensation. Vapor condenses on the external surface of single and multiple, horizontal plain and finned tubes. The refrigerants used in this study are R-12 and R-22, while the oil is alkylbenzene-based.