Deciphering the heat and mass transfer behaviors of staggered tube bundles in a closed wet cooling tower using a 3-D VOF model

Abstract

This article presents a three-dimensional CFD model to describe the counter-current air-water flow across the staggered tube bundles in a bench-scale closed wet cooling tower by combining VOF multiphase method and SST k-ω turbulence model. The proposed model can investigate the interfacial heat-mass transfer and complex interaction mechanisms among multiple tubes. Through adding the shear force term and water evaporation in the model, the circumferential distribution of the falling film and air humidity fields are obtained, and the effects of the spray density and the air velocity on the falling film flow mode, air humidity, and transfer process are studied. The results show that, the thinnest water film and maximum evaporation rate are obtained when the circumferential angle is 75° and the spray density is 0.048 kg m−1 s−1, respectively; the air Reynolds number has a greater influence on multiphase heat and mass transfers than that of the spray water Reynolds number.