Numerical Simulation of a Wavy Fin-and-Tube Heat Exchanger Under Wet Conditions

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In order to analyze the influence of condensation behavior on the heat transfer process of large heat exchangers under wet conditions, a three-dimensional numerical model of condensation heat transfer of twelve-row wavy fin-and-tube heat exchangers under wet conditions was established. The effects of inlet velocity and relative humidity on heat and mass transfer characteristics were investigated. Through the analysis of the field synergy principle, it is found that the wavy fin can effectively improve the synergy between the velocity field with the temperature field and the concentration field. The wavy fin not only increased the disturbance of fluid but also continuously disrupted the developments of thermal and mass concentration boundary layers, thereby greatly enhancing the heat and mass transfer. The condensation mainly occurs on the first six pipe rows, and the increase of inlet velocity makes the condensation area obviously larger. The inlet relative humidity has little effect on the temperature distribution and sensible heat transfer under wet conditions but has a significant effect on the latent heat transfer and total heat transfer. Finally, the relationship for convective heat transfer coefficients under wet and dry conditions is obtained by multivariate fitting.