确定对流传质系数的膜渗模型

Film-Penetration Method to Determining the Convective Mass Transfer Coefficient

针对对流传质过程研究中两个具有代表性的模型理论——薄膜模型理论和渗透模型理论确定的对流传质系数与实验结果存在一定不一致的问题，在分析薄膜模型理论和渗透模型理论特点的基础上，基于边界层理论，提出了确定对流传质系数的膜渗模型．讨论了该模型理论的原理、对流传质系数的确定方法及系数的正确性、优越性，获得了利用膜渗模型确定的对流传质系数表达式，并与遵循薄膜模型理论、渗透模型理论及Frossling经验公式的对流传质系数进行了比较．结果表明：膜渗模型更符合边界层理论，能更合理的解释流动边界上的对流传质过程；对流传质系数与扩散系数的关系为D^n（n=0．5—1．0），符合经验公式及实际中大量实验结果．

In order to study the process of the convective mass transfer, many kinds of methods and models had been presented in the past. The FILM theory and the Penetration theory are the two representative theories. But there are some differences between the mass transfer coefficients form the two theories and the actual experimental result. Based on the boundary layer theory and the analysis of the characters of the FILM theory and the Penetration theory, the Film-Penetration model is presented. The principle of the model is discussed. With the model, the formulation for the mass transfer coefficient is deduced in details. The advantage and the correctness of the formulation are proved. The result shows that the Film-Penetration model is much fit for the boundary layer theory and is more reasonable to explain the process of the convective mass transfer, and the expression, to describe the relation between the mass transfer coefficient and the diffusion coefficient, is D^n （ n = 0. 5 - 1.0） and is much fit for the actual experimental result.