切应力作用下降膜吸收过程特性研究

Research on effect of shear stress on performance of falling film absorption process

利用CFD软件Fluent,通过数值模拟方法研究了溴化锂溶液降膜吸收过程.模型中考虑了界面切应力对于降膜吸收特性的影响,给出了不同界面切应力下主体温度、浓度随着下降距离的变化及热量、质量通量随着下降距离的变化.模拟结果表明:切应力对降膜吸收过程有一定的影响.与无切应力相比,正向切应力对降膜吸收过程不利,而逆向切应力对降膜吸收过程有利.这主要是由于切应力的存在改变了液膜内的速度分布及液膜在吸收器内的停留时间.

Using CFD （computational fluid dynamics）software Fluent,numerical simulation of aqueous lithium bromide falling film absorption is conducted. In the present model, effect of interfacial shear stress on the performance of falling film absorption is considered.Profiles of bulk temperature and concentration against downstream position are presented.So are heat flux and mass flux.The experimental results indicate that shear stress has some effects on absorption process. Compared to that without shear stress,positive shear stress deteriorates the absorption process while negative shear stress enhances the absorption process,which can be explained that shear stress changes the velocity profiles in the falling film and resident time of liquid film in the absorber.