Condensation Heat Transfer in a Horizontal Rotating Cylinder

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Heat transfer in laminar film condensation on the inner surface of a cylinder rotating about its horizontal axis are investigated experimentally and theoretically.The experimental data are obtained with the acrylic cylinder of 294 mm ID and the stainless steel cylinder of 310 mm ID, and R113 as condensation fluid. Condensed liquid are removed by the plate type scraper, installed on the inner surface at the top of the rotating cylinder, so that very thin film of condensed liquid are formed on the inner surface of cylinder. As the experimental results, over-all coefficient of heat transfer between condensing vapor and the outer surface of the cylinder wall are shown to be affected by the heat conduction resistance ratio of the wall and the condensed film, and rotation rates.Theoretical studies are performed by means of numerical method, based on the assumption of very thin film. At low rotation rates, the condensed liquid backs to the bottom of the cylinder. This rotation rates limit for the back of liquid (critical rotation Froud number) is shown as a function of the ratio of sensitive and latent heat, and Prandtl number. Nusselt number based on over-all heat transfer coefficient,Num are shown by the two parameter and to be good agreement with the experiments.At region near the critical rotation Froud number, effects of the angle position of the scraper on Num become notable, this optimum angle is shown also.