The influence of surface roughness on the hydrodynamics of the falling water film in cooling towers

Igor Kuzmenko, Alexandre Gourjii

Abstract


This paper sets out the results of experiments for falling film at Rew = 70 ... 340 in the vertical channel of two coaxial tubes, ∅\varnothing∅ 37/17 mm, 1 m high, for a countercurrent air flow with Reair = 2200 ... 104. Subject to investigation was falling film on smooth and capillary-porous wall surfaces at constant film thickness greater than the height of the capillary-porous coating (0.3 mm). It was established that film thickness is weakly dependent on the velocity of the countercurrent airflow at w\ w w air = 1.7…7.3 m/s. The water concentration on a smooth surface is 2 times higher at the same film thickness. The results of flooding in a channel with a smooth wall surface confirm the validity of the Wallis equation with deviation up to 20%.

Keywords


falling film, countercurrent flow, capillary-porous wall surface, film thickness

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