title: Computational analysis of fluid dynamics in pharmaceutical freeze-drying.
abstract: Analysis of water vapor flows encountered in pharmaceutical freeze-drying systems, laboratory-scale and industrial, is presented based on the computational fluid dynamics (CFD) techniques. The flows under continuum gas conditions are analyzed using the solution of the Navier-Stokes equations whereas the rarefied flow solutions are obtained by the direct simulation Monte Carlo (DSMC) method for the Boltzmann equation. Examples of application of CFD techniques to laboratory-scale and industrial scale freeze-drying processes are discussed with an emphasis on the utility of CFD for improvement of design and experimental characterization of pharmaceutical freeze-drying hardware and processes. The current article presents a two-dimensional simulation of a laboratory scale dryer with an emphasis on the importance of drying conditions and hardware design on process control and a three-dimensional simulation of an industrial dryer containing a comparison of the obtained results with analytical viscous flow solutions. It was found that the presence of clean in place (CIP)/sterilize in place (SIP) piping in the duct lead to significant changes in the flow field characteristics. The simulation results for vapor flow rates in an industrial freeze-dryer have been compared to tunable diode laser absorption spectroscopy (TDLAS) and gravimetric measurements.
authors: School of Aeronautics and Astronautics, Purdue University, West Lafayette, Indiana 47907, USA. alexeenk@purdue.edu
authors: Alina A
authors: AA
authors: Alexeenko
authors: Arnab
authors: A
authors: Ganguly
authors: Steven L
authors: SL
authors: Nail
mesh_terms: D003198:Computer Simulation; D004867:Equipment Design; D005612:Freeze Drying / Q000295:instrumentation* / Q000379:methods*; D008956:Models, Chemical; D014618:Vacuum; D014835:Volatilization; D014867:Water / Q000737:chemistry
chemical_list: D014867:Water