The formation and distribution of condensed vapor during the freeze drying of porous polymer hydrogels are numerically evaluated. The sublimation-condensation model is developed by CFD simulation to investigate phase change in the freeze drying process. Scanning electron microscopy (SEM) was used to investigate the structure of cross-linked gelatine and an idealized geometry model was applied to determine interconnected pore structure. The simulation explores the influence of various parameters on condensation and drying rate, including temperature, pressure, pore diameter, liquid volume fraction, and porosity. The optimum temperature is estimated to enhance drying rate and decrease condensation in the freeze drying process. The results show that condensation in porous materials depends on capillary forces and cause invasion percolation patterns.