Film-wise condensation of R-134a, R-1234ze(E) and R-1233zd(E) outside the finned tubes with different fin thickness

Abstract

Film-wise condensation of R-134a, R-1234ze(E) and R-1233zd(E) outside two enhanced tubes was experimentally investigated. The two tubes have the same fin density and similar fin height while the fin thickness is different. In the experiment, the saturation temperature was 36 °C. Heat flux was in the range of 20–90 kW·m−2. It was found that R-134a was more efficient than other refrigerants and gave the highest heat transfer performance outside the two tubes. R-1233zd(E) was the lowest. Condensing heat transfer coefficient of R-134a was approximately 2 times higher than R-1233zd(E). As heat flux was higher than 20 kW·m−2, condensing heat transfer coefficient of R-134a and R-1234ze(E) all decreased as the increasing of heat flux. While for R-1233zd(E), up to the heat flux of 90 kW/m2, the condensing heat transfer coefficient is ever-increasing as the increasing of heat flux. The condensing heat transfer of R-134a was 10–20% higher than R-1234ze(E). The trend of variations for the heat transfer performance of R-134a and R-1234ze(E) was similar. The present work examined the heat transfer characteristics of finned tubes with different fin thickness. It is helpful for the designers to summarize the heat transfer performance of some new HFOs refrigerants having the potential to be used in the water cooled chillers or heat pumps.