During microencapsulation, agitation is typically required to achieve the homogeneous dispersion of the reaction mixture, with the mixing and dispersion efficiency within the reactor being predominantly determined by the rotational speed. However, when the agitation speed exceeds a certain threshold, cavitation occurs during the stirring process. This cavitation phenomenon can significantly influence the properties of the resulting microcapsules. Therefore, this study combines the CFD simulation method with microcapsule preparation experiments, focusing on the occurrence of cavitation during the stirring process and its effect on the particle size of the prepared microcapsules. The CFD simulations analyzed flow field characteristics under different agitation speeds within the beaker, including phase distribution contours, streamline patterns, turbulent kinetic energy fields, and shear stress distributions. Different fluid flows were established by changing the rotating speed of the paddle, and the influence of each fluid flow on the particle size and distribution of the prepared microcapsules was determined. Particular emphasis was placed on examining the influence of rotational speeds ranging from 550 to 850 rpm on microcapsule particle size. Experimental validation confirmed that the impeller speed of 650 rpm provided superior flow field control, yielding microcapsules with the narrowest particle size distribution. This study elucidates the mechanism through which cavitation influences the microencapsulation process, thereby providing both theoretical insights and experimental support for the optimization of microcapsule preparation techniques.
tian et al. (Tue,) studied this question.