RP-469 -- Effect of Oil on Heat Transfer and Pressure Drop Inside Augmented Tubes During Condensation and Evaporation of Refrigerants PDF

Although the refrigerant in vapor compression refrigeration systems always contains some lubricating oil, and the refrigeration industry shows a growing interest in the use ofin-tube heat transfer augmentation, there has been no research into the effects of oil on the two-phase heat transfer and pressure drop inside augmented tubes. This lack of knowledge has led to the current research.A review of the literature emphasized the effects of oil on evaporation and condensation inside smooth tubes and pure refrigerant evaporation and condensation inside augmented tubes. Also reviewed were papers dealing with properties of refrigerant-oil mixtures; pool boiling, vapor space condensation, and adiabatic transport of refrigerant-oil mixtures; and past correlations for heat transfer and pressure drop of pure refrigerant and refrigerant-oil mixtures in smooth and augmented tubes.