对流边界条件下竖板降膜除湿过程中传热传质的数值模拟

针对竖板降膜(层流)溶液除湿空调系统,建立了溶液降膜过程传热传质的数学模型,给出了对流换热边界条件下过程的数值解.模拟了三种不同冷却条件下的降膜除湿过程.结果表明,当对流换热系数较小时,与绝热边界有相似的发展趋势;而当对流换热系数较大时,则接近于等温条件下的规律.同时,模拟结果还给出了不同的无量纲吸收热λv和刘易斯Le对降膜内Nusselt数和Sherwood数的影响,表明无量纲吸收热的改变不影响Nu数和Sh数在流动方向上的最终渐近值.

NUMERICAL SIMULATION OF HEAT AND MASS TRANSFER FOR DESICCATING PROCESS IN FALLING LIQUID FILM UNDER CONVECTIVE BOUNDARY CONDITIONS

A heat and mass transfer model for falling liquid film of laminar flow in liquid desiccant air- conditioning system was prerented. Numerical simulation was conducted under three different convective boundary conditions. The results show that heat and mass transfer process at small convective hear transfer coefficient is clost to that of adiabatic boumdary condition, while the heat and mass transfer behavior at larger convective hear transfer coefficient is similar with constant temperature boundary condition. In addition, the numerical results gave out the influence of dimensionless absorption heat and Lewis number on the variation of Nusselt and Sherwood number and the saymptotic values of Nusselt and Sherwood number along the flow direction do not depend on the dimensionless heat of absorption.