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Horizontal Flow Boiling of Single Component and Binary Refrigerant Mixtures.


pdf icon Horizontal Flow Boiling of Single Component and Binary Refrigerant Mixtures. (14984 K)
Kedzierski, M. A.; Didion, D. A.

ER-8006-2; Research Project 2792-09; 106 p. 1993.

Sponsor:

Electrical Power Research Inst., Palo Alto, CA

Available from:

Electrical Power Research Inst. (EPRI), Palo Alto, CA

Keywords:

refrigerants; heat transfer; degradation; nucleation; ozone; evaporation; flow boiling; visualization

Abstract:

This report contains three studies on refrigerant mixture heat transfer funded by NIST and EPRI (RP 80006-21). The first study, Visualization of Nucleate Flow for an R22/R114 Mixture and Its Components, is presented in section 1. It investigates the phenomena of the suppression of nucleation due to increased mass flow while all other conditions are fixed. This study also compares the nucleate activity of the binary mixture to the nucleate activity of the pure components. The fluids investigated are a 37.7% mole R114 binary mixture and the individual components R22 and R114. The second study, Causes of the Apparent Heat Transfer Degradation for Refrigerant Mixtures, is presented in section 2. It investigates the causes of the apparent heat transfer degradation associated with horizontal - annular flow evaporation of refrigerant mixtures. For horizontal-annular flow evaporation, most of the heat transfer degradation is a consequence of the use of the locally uniform equilibrium temperature in the measurements and calculation of the heat transfer coefficient. The remainder of the heat transfer degradation is due to nonlinear mixture property effects. The focus of the study was to determine the magnitude and the cause of the individual components of the heat transfer degradation of the studied mixtures. The third study, A Comparison of Experimental Measurements of Local flow Boiling Heat Transfer Coefficients for R11 and R123, is presented in section 3 and presents a comprison of the measured horizontal, smooth-tube, flow boiling heat transfer coefficient of R11 to that of its proposed near ozone safe replacement, R123. The fluid properties of R11 and R123 are similar. The flow boiling data for the two fluids are similar for the convective region. However, the heat transfer coefficient for R11 in the nucleate flow boiling region was consistently observed to be, on average, 8.5% to 33% larger than that for R123. For the convenience of the reader, both the R123 and R11 property data used in this study are presented.