Modeling and simulation of rapid expansion of supercritical solutions

Abstract

-Rapid expansion of supercritical solution (RESS) is a promising technique for microparticle production. The literature points out that the RESS technique can be applied to process a wide range of materials including ceramics, polymers, biopolymers, pharmaceutics, 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. In this context, this work is focused on the analysis of process hydrodynamic modeling and on phase equilibrium modeling (thermodynamic modeling of supersaturation), with a phase stability test coupled. The Gibbs tangent plane distance for the phase stability test was minimized using the simulated annealing algorithm. The results showed that the thermodynamic variables exert a remarkable effect simulated variables (temperature, velocity, density and degree of supersaturation) for the profile.

Particles Formation Using Supercritical Fluids

“…Supersaturation values were very high in the free-jet expansion region, but depending on the preexpansion conditions, the supersaturation profile in the free jet region was quite different. These observations suggest that pre and post expansion conditions can have a remarkable effect on the characteristics of precipitated particles (Corazza et al, 2006). The results presented in this work indicate that the fluid residence time in the capillary region was very low, and thus the mechanism for microparticle formation could also be affected by mass transfer phenomena in addition to thermodynamic equilibrium.…”

Mean Aspects Controlling Supercritical CO2 Precipitation Processes

“…Corazza et al pointed out that the supersaturation profile in the free jet region depends on the pre-expansion conditions that could have a remarkable effect on the characteristics of precipitated particles [17]. Higher pre-expansion pressure and lower temperatures are recommended to obtain smaller particle size of benzoic acid, cholesterol, and aspirin precipitated by RESS process [16].…”

“…Numerous investigations in particle formation with supercritical fluids have been carried out to shed light the parameter to govern the crystallization mechanism using CO 2 as antisolvent (SAS) [2][3][4][5][6][7][8][9][10][11][12][13][14][15] or as solvent (RESS) [16][17][18][19][20][21][22][23][24][25][26][27][28].…”

Particle Formation and Product Formulation Using Supercritical Fluids

“…It is generally possible to model the formation of particles with the RESS process by simultaneously resolving the mass, momentum, and energy balances in combination with the proper EoS and general dynamic equation. The most developed models are onedimensional flow models (69)(70)(71)(72)(73)(74)(75)(76)(77)(78); only few well-developed works consider two-dimensional flow (79,80). The particle formation process was also considered at the molecular level, and molecular simulation methods (81)(82)(83) have been employed beside macroscopic fluid dynamics simulations.…”