CFD Based Correlation for Effective Vapor Diffusivity of Porous Gelatin in Freeze Drying Process

Ascertainment of effective diffusion coefficient in porous solids is difficult and will determine empirically. A model to assess the relationship between the effective vapor diffusivity and porosity has been developed by computational fluid dynamic techniques and experimental data of freeze dryer set up. Continuity, momentum and energy equations with heat and mass transfer models solved for idealized geometry of porous hydro gel and diffusion mechanism duo to pressure gradient in freeze drying porous media was studied for two phase liquid-vapor as mixture model multiphase flow. The effective vapor diffusivity at freeze drying has been determined as a function of porosity and water volume fraction at vapor diffusion and condensation process in freeze dryer. The simulation results are in a quite fair agreement with empirical models to predict effective vapor diffusivity.