液-液分散模型及滴内传质

研究了湍流场中液－液分散和滴内传质的非稳态过程。结果表明，Ｓａｎｔｅｒ平均滴 径随时间的变化可以用滴群平衡方程和简化的液滴破碎函数和聚合函数描述．分散初 始阶段并且分散相存留量较低时，可以略去聚合项，液滴破碎过程可以简化为等体积的 二分裂过程。滴内传质可以用Ｄａｎｃｋｗｅｒｔｓ表面更新理论描述，界面更新速率在数值上 相当于单位时间滴群比表面的更新分数。

Model of Liquid- Liquid Dispersion and Mass Transfer in Drops

The unsteady-state liquid-liquid dispersion and diffusional mass transfer in drops in turbulent fields were studied. It was found that the relation between the Sauter mean diameter and time could be predicted by the drop population balance equation (PBE) with negligible coalescence terms during the initial dispersion at low holdup and the behavior of drop breakage could be simplified as the binary equal volume breakage. The results at higher holdup should be corrected for the coalescence terms. The simplified drop breakage or coalescence frequency function was given. The transient mass transfer in drops was estimated by using Danckwerts' surface renewal theory. The fraction of surface variation of drops per unit time was numerically taken as the fractional rate of surface renewal.