Experimental Condensation Characteristics, Using HFC Refrigerants in Micro-fin Tubes

Micro-fin (MF) tubes, which are utilized in condensers and evaporators in heating and cooling systems, are employed in these components. In the current work, experimental investigations are made of the frictional pressure drop (PD) and heat transfer coefficients (HTC) while the condensation of hydro-fluoro-carbon (HFC) refrigerants. Horizontal smooth tube (ST) and micro-fin (MF, 15˚ and 18˚ helix angles, 9.52 mm OD) tubes vapour quality of 0.1 to 0.9 are used in experiments, respectively. The computed local condensation HTCs for HFC refrigerants inside of the MF tube are 1.21–1.82 and 1.18–1.54 times as large as the smooth tube (ST). Refrigerant R-134a has higher HTCs and frictional PDs than R-404A both in smooth tubes as well as micro-fin tubes. A new correlation has been proposed for calculating HTCs in micro-fin tubes by using experimental data of this study. Comparison of experimental data has been made with predicted values obtained from correlations proposed by other similar research studies. For refrigerants R-134a and R-404A, oil concentrations ranged between 1.31 and 1.55%, respectively.