FILM CONDENSATION OF STEAM ON HORIZONTAL FINNED TUBES: EFFECT OF FIN SPACING.

The film condensation heat transfer performance of six externally finned copper tubes has been evaluated. All tubes had rectangular-shaped fins with a height and thickness of 1 mm. The spacing between fins was 0. 5, 1. 0, 1. 5, 2. 0, 4. 0, and 9. 0 mm. Data were also obtained for a smooth tube whose outside diameter of 19. 0 mm was equal to the diameter at the base of the fins for all of the finned tubes. Tests were performed both at atmospheric pressure and under vacuum (approximately 11. 3 kPa). Steam flowed vertically downward with a velocity of approximately 1 and m/s at atmospheric pressure and under vacuum, respectively. The smooth tube was fitted with wall thermocouples for the evaluation of the water-side heat transfer coefficient.