超临界流体快速膨胀过程的建模和模拟

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 26 553, the diameter of the minimum particles is 8 μm, and the proportion of the fine particles is 43.39%.