Kinetic approach to modeling the freezing porous media: Application to the food freezing

• A new kinetic approach and general model for the freezing porous media is presented.
• It is assumed that the phase transition process occurs according to non-instantaneous kinetics.
• For meat freezing the technological parameters are obtained.
• It is shown that the thermal and moisture fields’ structure is homogeneous.
• The results of modeling are in a good agreement with experimental investigations.

A new kinetic approach and general model for the processes of heat and mass (moisture) transfer in porous media under phase transition conditions is developed. It is assumed that the water crystallization process occurs according to non-instantaneous kinetics. As is shown in the study, this approach gives a possibility to describe the real process more completely and to reflect the main regularities of the phenomenon.Since the problem is significantly nonlinear the numerical method for the solution is applied. For the technological process of meat freezing, the phase front propagation and also temperature, moisture and ice distributions are obtained. It is shown that the thermal and moisture fields are homogeneous and therefore for considered initial data the freezing process is optimal from the view point of minimization of the energy consumption. The results of modeling are in a good agreement with experimental investigations, the discrepancy between them does not exceed 4.5%. The analysis indicates that simulation of the phase transition zone as an infinitely thin front in freezing process, which is an approach incorporated in most theoretical models, is not suitable for the non-equilibrium water crystallization processes and, thereby, conforms the validity of the kinetic approach.