A comparison of experimental measurements of local flow boiling heat transfer coefficients for R11 and R123

This paper presents a comparison of the measured horizontal, smooth-tube, flow boiling heat transfer coefficient of R11 to that of its proposed 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. The influence of Reynolds number and heat flux on the heat transfer-thermodynamic quality relationship is also presented. Predictions of the heat transfer coefficient with two open literature flow boiling correlations were compared to the measured data. The heat transfer coefficients predicted with the correlations were, on average from 13% to 57% greater than the measured heat transfer coefficients. Not until recently has there been sufficient thermodynamic or transport data for R123 to perform an accurate heat transfer analysis for that fluid. Great care was taken to ensure that the most carefully measured property data were used for this analysis. For the convenience of the reader, both the R123 and R11 property data used in this study are presented