Mathematical modelling of freezing of vacuum-packed beef with irregular geometries and structures

This study focuses on simulating the freezing process of meat with irregular geometries and variable composition. A conjugated heat transfer two-dimensional model was implemented to predict the product's temperature, air velocity and temperature over time. The model considered convective and conductive heat transfer, using apparent specific heat for the phase change. Different domains of muscle and fat tissues were modelled from image capture and computer-aided design (CAD) digitalisation to calculate thermophysical properties of meat slices. The convective coefficients were calculated from dimensionless numbers. The model was solved using COMSOL® Multiphysics v.5.6 and validated by freezing the samples of packaged bovine top-round beef in a freezing tunnel at air temperatures from −18°C to −40°C and air velocities from 1 to 5 m/s. Internal temperature and air velocities, as well as products, were measured. Results showed that the model accurately predicted the product's temperature at several air temperatures and velocities. The experimental error varied between 5.23% and 12.90%. The air temperature had more influence on freezing time than velocity. The results revealed the convenience of using images and CAD digitalization to represent irregular geometries and variable composition of each meat tissue for accurate freezing process prediction. The model can predict freezing times in the future control of freezing chambers and equipment.