Condensation Heat Transfer in a Horizontal Rotating Cylinder

对绕水平轴旋转圆柱内表面层流膜状凝结换热进行了实验研究和理论分析，获得了内径为294 mm的丙烯酸圆柱和内径为310 mm的不锈钢圆柱，凝结流体为R113的实验数据。冷凝液由安装在旋转圆筒顶部内表面的板式刮板清除，使圆筒内表面形成极薄的冷凝液膜。实验结果表明，壁面与冷凝液膜的导热阻力比和转速对冷凝水蒸气与壁面之间的总传热系数有影响，并基于极薄液膜的假设，用数值方法进行了理论研究。在低转速下，冷凝的液体回到圆筒的底部。液体背面的旋转速率极限（临界旋转弗劳德数）被示出为敏感热和潜热的比率以及普朗特数的函数。用这两个参数计算了基于总传热系数的努塞尔数和阻力系数，与实验结果吻合较好，在临界转速弗劳德数附近，刮板角位置对阻力系数的影响显著，并给出了最佳刮板角。

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.