Experimental Study on Film Condensation of R1234yf Outside Finned Tubes
Rand A. AL-Taee*, Alaa R. Al-Badri
Mechanical Engineering Department/ Engineering College/ Wasit University / Wasit, Iraq.
This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
The global warming problem motivated researchers to find alternatives to substances that contribute in this problem. The refrigerant R134a (HFC134a) was classified as one of unfriendly gases to the environment. Therefore, the refrigerant R1234yf has been used as an alternative to refrigerant R134a refrigeration in air conditioning systems. In this paper, the condensation heat transfer coefficient (HTC) of refrigerants R1234yf & R134a were measured on plain & two low-fin tubes. The finned tubes have fins per inch (FPI) equals to 25 & fin heights of 1 & 1.4 mm. The condensation process was investigated at condensing pressures 7.5, 8, 8.5, & 9 bar with water inlet temperature between 19 & 21°C. The findings indicated that condensation HTCs on the plain tubes are well predicted by the Nusselt theory within MAPD 2% for R134a & 2.7% for R1234yf. The condensation HTC decrease in proportion to the rise in the heat flux. Overall HTCs increase with the increase in LMTD. The refrigerant R134a resulted in higher HTC than R1234yf for finned tube with fin height 1.4mm. An enhancement factors of 10 times was gained by the finned tube with 1.4 mm fin & R1234yf compared to plain tube & 9 times with refrigerant R134a. The MAPD of predicted HTC results is 65 % for Briggs & Rose  & 30 % for Murata & Hashizume  when compared to the experimental values for low- fin tubes.