Precision determination of film condensation row effect of R134a condensation on an array of horizontal plain tubes

Abstract The effect of condensate inundation on the film condensation heat transfer of R134a on an array of 15 horizontal plain tubes was experimentally investigated with a new experimental method. This method could accurately determine the row effect. A test facility, which has a test section and contains two arrays of 17 horizontal plain tubes, was constructed to realize the new experimental method. The outer diameter of the plain tube was 19.05 mm, and the tube length in the test section was 500 mm. The test condition was conducted at saturation temperatures of 38.7 °C, 40.6 °C, and 43.5 °C and heat flux of 14.8, 18.0, and 21.6 kW/m2. The experimental error of the determined row effect factor was within ±2.0%, which was only 14.0% of that of the common experimental method (±14.5%). Experimental results revealed that the film condensation row effect factor for the plain tube initially decreased rapidly and then increased gradually with the number of tube rows. In comparison with the saturated temperature, the row effect was more sensitive to heat flux condition for n range from 8 to 15. The precision row effect can be used as benchmark data to perfect and develop the film condensation theory.