Flow condensation heat transfer performance of natural and emerging synthetic refrigerants

Abstract

There is great interest in predicting flow condensation heat transfer for lower global warming potential (GWP) fluids. This paper analyzes the efficacy of common flow condensation correlations developed for particular fluids in order to identify their suitability to predict heat transfer performance of low GWP fluids. Condensation heat transfer data were extracted from the literature, including 19 papers and 1,473 data points for natural refrigerants [i.e., ammonia (R717), CO2 (R744), propane (R290), isobutane (R600a)] and 35 papers and 5,030 data points for synthetic refrigerants [i.e., R12, R1234yf, R1234ze(E), R1234ze(Z), R22, R32, R41, R123, R125, R134a, R142b, R152a, R161, R404A, R410A, R448A, R449A, R450A, R452B, R454C, R455A, R513A] encompassing tube diameters of 0.1–11.5 mm, mass fluxes of 55–1200 kg/m2s, and saturation temperatures of -25 °C–65 °C. Correlations analyzed included (Akers et al., 1959; Cavallini et al., 2006; 2011; Kim and Mudawar, 2013; Macdonald and Garimella, 2016; Shah, 1979, 2009, 2013, 2016) and (Traviss et al., 1973) for smooth tubes and (Chamra et al., 2005) and (Kedzierski and Goncalves, 1999) for enhanced tubes. Since most studies did not report wall temperature, correlations which relied on wall temperature directly or indirectly were excluded from the analysis. For synthetic refrigerants, mean average error (MAE) ranged from 6% to 257%, and (Cavallini et al., 2011) and (Kim and Mudawar, 2013) were the best predictors for emerging synthetic refrigerants. The (Kim and Mudawar, 2013) correlation was found to best predict the heat transfer performance for propane and R600a data, but most correlations did not accurately predict ammonia and CO2 flow condensation.