2004 年 70 巻 693 号 p. 1279-1284
In the previous paper, numerical model for absorption within vertical pipes was proposed and compared with the experiments. Agreements were good for pipes with OD 28-15 mm but at 10 mm pipe experiments fell bellow the predicted values. For smaller diameters, the difference between the surface area of the falling liquid film and that of the outer surface of the pipe is not negligible and the thickness of the liquid film is neither negligible. In this paper new model is formulated in cylindrical coordinates and experiments using pipes with 9.52 mm and 7 mm OD are done. Smooth pipes and two kinds of internally finned pipes, which are originally developed and used to enhance the heat transfer characteristics of evaporator and condenser of refrigerator using HFC as refrigerant, are tested in the experiments. The absorption performance is enhanced by 30% compared to the smooth pipes, but the difference between the finned pipes are small.