Effect of Lubricant on R410A Horizontal Flow Boiling

摘要

This paper experimentally determines the effect of lubricant on R410A horizontal flow boiling. A baseline was established by measuring the convective boiling heat transfer performance of pure R410A. In addition, the heat transfer performance of an R410A/lubricant (99.6/0.4) mixture was measured and compared to that of the lubricantfree refrigerant. The measured convective boiling Nusselt numbers for the lubricant-free R410A and R410A/lubricant mixture were compared to an existing correlation. The correlation was shown to predict 71 percent and 83 percent of the lubricant-free R410A and the R410A/lubricant Nusselt numbers to within - 20 percent, respectively. The mean degradation in the heat transfer performance with the addition of lubricant was approximately 6.7 percent. A measurement technique for observing the fluorescence of the lubricant in the annular flow was developed. Further improvements in the technique are necessary before it can be used to visualize the distribution of lubricant within the flow.