Experimental study of falling film flow characteristics outside shaped tubes related to a spiral-wound heat exchanger

In this paper, the falling film flow and the effects of the marine inclination on the shell-side flow pattern outside the sinusoidal corrugated tube and the square-corrugated tube related to a spiral-wound heat exchanger are experimentally studied using n-pentane as the testing fluid. The flow field phenomenon and the film thickness are investigated with the utilization of high-speed camera technology. The results show that the critical Re of the flow regime transition of the falling film outside the square-corrugated and sinusoidal corrugated tubes is quite different from the critical Re of the flow regime transition of the falling film outside the horizontal circular tube. The tube shape has a certain impact on the falling film flow characteristics. Moreover, under the inclination conditions, the liquid column and liquid film will move toward the inclined side. The resistance ability of the inclination of the square-corrugated tube is better than the resistance ability of the sinusoidal corrugated tube due to the dragging effect.