超临界流体快速膨胀过程的建模和模拟

Modeling and simulation on rapid expansion process of supercritical solutions

超临界流体的快速膨胀(RESS)是一种很有前途的微粒制备技术,RESS技术可以应用于陶瓷、聚合物、生物聚合物、药剂学和有机化合物等材料的加工过程。为了充分了解RESS过程的特点,有必要对该过程的流体动力学,以及微粒形成过程进行建模和模拟研究。这项工作重点分析了超临界二氧化碳的RESS过程在毛细管喷嘴附近流体力学和粒子流的建模和过程模拟。结果表明:在纯流体流场模拟中,工艺参数(温度、速度、密度和马赫数)在流场中具有明显的变化,且在毛细管出口处变化最为显著;在粒子流流场模拟中,实验追踪的最大粒子数为26553,最小微粒的直径为8μm,其细小微粒占比达43.39%。

The rapid expansion of supercritical solution(RESS)is a promising technique for microparticle preparation.RESS technique can be applied to process a wide range of materials including ceramics,polymers,biopolymers,pharmaceuticals,and organic compounds.In order to achieve an adequate understanding of the RESS process,it is necessary to conduct more comprehensive studies involving the hydrodynamic modeling of the fluid flow through the capillary,the phase behavior of a expanding mixture,and also with regard to the microparticle formation mechanism.It is necessary to conduct modeling and simulation for the fluid dynamics and the particles formation of the process.In the work,the modeling and simulation of hydrodynamics and particle flow near capillary nozzles for RESS processes of supercritical carbon dioxide were investigated.The results show that the process parameters(temperature,velocity,density and mach number)have the obvious changes in the simulation of the pure fluid flow field,and the changes are most significant at the capillary outlet.In the particle flow field simulation,the maximum particle number tracked by the experiments is 26553,the diameter of the minimum particles is 8μm,and the proportion of the fine particles is 43.39%.