Condensation heat transfer for downward flows of superheated steam-air mixture in a circular pipe

We measured the radial and axial temperature distributions of a saturated steam-air mixture in a vertical circular pipe (diameter, 49.5 mm; cooling height, 610 mm) in our previous study. Those of a superheated steam-air mixture in the same experimental setup were measured in this study. The condensation heat flux qc and heat transfer coefficient hc for the superheated mixture were evaluated, and they were compared with those for the saturated mixture. There was no large difference in qc between the saturated and superheated mixtures. The heat transfer coefficient hc (which was evaluated for the saturation temperature) for the superheated mixture agreed with that for the saturated mixture. hc computed with the diffusion layer model for saturated temperature agreed well with the hc measured for the superheated mixture.