Evaporation heat transfer of R-32, R-134a, R-32/134a, and R-32/125/134a inside a horizontal smooth tube

Evaporative heat transfer coefficients of R-32, R-134a, R-32/134a, and R-40 7C (R-32/125/134a: 23/25/52 wt%) have been measured in a horizontal smooth tube. Experiments were conducted for test section average temperatures of - 12.0-17.0 degrees C, with a mass flux of 240-1060 kg m(-2) s(-1), and a hea t flux of 4.1-28.6 kW m(-2). Evaporative heat transfer characteristics of R -407C as a possible alternative to R-22 have been compared with those of R- 22. A new correlation based on superposition model for pure refrigerants an d refrigerant mixtures was presented. Experimental results were compared wi th several correlations which predict evaporative heat transfer characteris tics. Comparison with the experimental data in the open literature showed t hat our correlation gave a satisfactory result. (C) 2000 Elsevier Science L td. All rights reserved.