非牛顿流体薄膜流中传质和传热的理论研究

本文从分析服从幂律的非牛顿流体薄膜流中速度分布入手,将其与扩散（导热）微分方程相结合,对不同的气液接触时间或距离进行了理论计算。 本文对方程给出了当流体的流变指数n取任意正有理数值时无穷级数解的求法。在此基础上,我们利用四阶Runge-Kutta法与Wegstien迭代法,求出了流变指数n为1/4,1/3,1/2,1/1.4,1/1.2,1,1.25,2.5,∞等一系列局部Sh数值与平均数值;当n=1即变为牛顿型流体时,与文献的结果十分吻合。

A Theoretical Study of Mass and Heat Transfer in Film Flow of Non-Newtonian Power Law Fluids

The exact expressions of concentration and local or average Sherwood number, Sh or Sh for non-Newtonian power law fluids when the flow index n takes any positive rational value, have been obtained by solving the differential equation of diffusion together with the velocity distribution in the falling film. The use of Fourth-order Runge-Kutta method and Wegstiens iteration method in the computer yields results which are a series of values of dimen-sionless concentration 0 local and average Sherwood number for n equal to 1/4, 1/3, 1/2, 1/1.4, 1/1.2, 1, 1.25, 2.5, and GO. When the flow index n=1, i. e. for Newtonian fluids, the result agrees well with the data from the literature. In the above equations, if we substitute thermal diffusivity a for the diffusivity D, local and average Nusselt number Nu, Nu for Sh, Sh, dimens-ionless temperature T=(Ts-T)/(Ts-T1) for , then, they may be used to evaluate the problem of heat transfer in film flow. All the results of calculation may be used for engineering design, but they must be applied within the limits of laminar flow or non-wavy film flow.