FILM –WISE CONDENSATION OF R1234yf AND R134a REFRIGERANTS ON FINNED TUBE WITH 32 FINS PER INCH

Abstract

Researchers have been motivating by the global warming challenge to develop alternatives substances to compounds that contribute to this problem. The refrigerant R134a (HFC134a) has been identified as one of the most environmentally damaging gases. As a result, the refrigerant R1234yf has been employed in air conditioning systems as a substitute to the refrigerant R134a. The condensation heat transfer coefficient (HTC) of the refrigerants R1234yf and R134a was measured on smooth and standard finned tubes in this study. The finned tube is characterized by 32 Fins per inch (FPI) and 1 mm fin height. The condensation process was investigated at 37°C and 40°C condensing temperatures and 16°C to 28°C water inlet temperatures. The Nusselt theory accurately predicted the condensation HTCs on the smooth tube within mean absolute percentage deviation (MAPD) of 5.3% for R134a and 4.7% for R1234yf. As the wall sub-cooling increases, the condensation HTC decreases. With a drop in LMTD, the overall heat transfer coefficient (HTC) rises. For finned tube, the refrigerant R134a showed a greater HTC than R1234yf. In comparison to smooth tube, the enhancement ratio in HTC was 78% at 37 and 82% at 40°C for R134a. The enhancement ratio with R1234yf was 65% and 81% at 37 and 40 ° C, respectively. The experimental data was compared with predictions of two previous analytical models for film condensation on finned tubes.