A predictive method to describe the boiling behavior of refrigerant-oil mixtures

Abstract

The need for efficient and environmentally safe refrigerants is of great concern to the Navy, and is driving them to explore the performance of alternate refrigerants for use in shipboard evaporators. Each time a new refrigerant is considered, one must also consider how oil contamination will affect its performance. The present study surveys the literature for a predictive technique to calculate the nucleate boiling heat transfer behavior of refrigerant-oil mixtures that is fundamental to the operation of refrigerant systems. There were three expressions found that could be considered for use. These expressions for the nucleate boiling heat transfer were empirically based formulations, which means that a new series of experiments must be conducted every time a different refrigerant-oil combination is considered for use. An expression that is currently under development for mixtures in general was found that is based only upon the thermophysical properties of the fluids and their mixtures. No empirical constants are necessary. The mass diffusion coefficient of the oil in the refrigerant is found to be the key property to be measured in order to evaluate the predictive capability of this expression. Experiments are proposed to obtain this key property and then to this expression will be developed as the experiments indicate are necessary