振荡流反应器内液-液两相流的数值模拟

Numerical simulation of liquid-liquid two-phase flow in an oscillatory baffled reactor

运用计算流体动力学和群体平衡模型相结合(CFD-PBM)的方法对振荡流反应器内液-液两相流进行CFD模拟。模拟结果表明,反应器内平均流速随振荡雷诺数的增大而增加,而且是最大振荡速度的(1.1～1.2)倍;分散相的体积分率随振荡雷诺数的增大基本不变。利用群体平衡模型得到了分散相液滴的粒径分布及其平均粒径,随着振荡雷诺数的增大,粒径小的液滴在分散相中所占的体积分率越来越大,液滴的平均粒径逐渐减小;在相同的振荡雷诺数下,振幅比频率对液滴粒径的影响更大,更有利于液滴间的破碎。通过得到的流场信息和液滴平均粒径可以预测两相间的传质特性,为反应器的设计、结构改进和优化提供理论依据。

A combination of Computational Fluid Dynamics and population balance model（CFD-PBM） is applied to simulate the drop size distributions and flow fields in a liquid-liquid oscillatory baffled reactor. Simulation results show that the average velocity of the reactor increases with the increase of oscillatory Reynolds number, and the velocity is （1.1-1.2） times to the maximum oscillatory velocityi volume fraction of dispersed phase remain basically unchanged with the increase of oscillatory Reynolds number. The size distribution and Santer mean diameter of dispersed phase have been calculated by population balance model, and the results show that the volume fraction of small size droplets increase with the increase of oscillatory Reynolds number, but the Sauter mean diameter of dispersed phase decrease with the increase of oscillatory Reynolds numbers; amplititude is more conducive to the droplets breakage which greater impact on the droplets distribution than the frequency at the same oscillatory Reynolds number. We can predict the mass transfer characteristics between two phases by the information of flow field and Sauter mean diameter which can provide a theoretical basis for the design of the reactor, structures improvements and optimization.