3699 -- Heat Transfer and Pressure Drop Characteristics of R-134a, R-32, and a Mixture of R-32/R-134a Inside a Horizontal Tube PDF

The heat transfer and pressure drop characteristics for R134a and R32 (both HFCs) and a mixture of R134a/R32 in a horizontal smooth tube during evaporation and condensation have been investigated experimentally. The mass flux of the refrigerants was varied during the course of the experiments. For the pure refrigerants, R134a and R32, the results obtained in this study showed that the evaporative heat transfer coefficients for R134a and R32 became, respectively, larger and smaller than those for R22 (an HCFC). Furthermore, the condensational heat transfer coefficients for R134a and R32 were larger than those for R22. For the mixture of R32/R134a (30%/70%) it was found that the evaporative and condensational heat transfer coefficients fell below the results for R22.

KEYWORDS: Heat flow, pressure drop, R134a, R32, mixtures, refrigerants, tubes, horizontal, fluorocarbons, experiment, evaporation, heat transfer coefficient, R22, condensation.