Condensation heat transfer and pressure drop characteristics of R-290 (propane), R-600 (butane), and a mixture of R-290/R-600 in the serpentine small-tube bank

This paper reports an experimental investigation of heat transfer and pressure drop behavior during condensation of R-600, R-600/R-290 (50 wt.%/50 wt.%) and R-290 in the three-line serpentine small-diameter (2.46 mm) tube bank. Heat transfer coefficients and pressure drop characteristics are measured at a constant heat flux of 5.2 kW/m2, mass flux (205–510 kg/m2 s) and refrigerant quality (0.15–0.84). The heat transfer coefficients for R-600, R-290/R-600 and R-290 are about 155%, 124% and 89% larger as compared with that for R-134a at the same conditions. The condensation flow frictional pressure drop for R-600, R-600/R-290 and R-290 in the present refrigerant mass fluxes are about 69%, 58% and 36% larger as compared with that for R-134a. In addition, the Dobson and Chato correlation provided the best prediction of the average heat transfer coefficients for the present refrigerants with experimental data with an average standard deviation of 12.8%. The pressure drop result shows a satisfactory agreement between the Friedel correlation and the experimental data, with a mean deviation of 15.3%.