Effect of wind speed on the spatial distribution of liquid film thickness outside the horizontal falling-film tube

Abstract

Wind speed has a significant impact on the flow behavior and distribution of falling-film in an evaporative condenser. This study aimed to investigate the effect of wind speed on the spatial distribution of falling-film outside a circular tube. Three liquids of different Reynolds numbers (368, 476, and 574) and three tube diameters (14, 19, and 25.4 mm) were investigated in this regard to assess the effect of wind with Reynolds numbers ranging from 0 to 2502 on averting the dry-spot. The model and numerical methods used were validated by comparing with experiments in existing literature without wind; then, the simulation results with the wind were further compared with our experimental results. The results showed that the wind blew the liquid film upwards, which led to an increase in the film thickness in the upper part of the tube and a decrease in the lower part. The variation in the magnitude of the liquid film thickness increases with an increase in wind speed. In the upper part of the tube, the wind prompts the location of the minimum film thickness close to the inlet liquid column, but it moves away from the inlet column in the lower part. The large liquid Reynolds number and small diameter weaken the effect of wind speed on the film thickness when the wind speed is constant. The results present a guiding significance for further research on evaporative condensers.