Solving Two-scale Transport Laws During Frying of Foods Using COMSOL Multiphysics
Microscale comprised of the scale of food biopolymers at which biochemical reactions and textural changes take place, and the macroscale was the scale of interaction of polymers with surrounding water, vapor and oil phases. Numerous novel equations such as generalized Darcy’s law based fluid transport equations for various phases; near-equilibrium equation governing phase change from liquid water to vapor or vice versa; and generalized Laplace law of heat transfer were obtained and implemented in COMSOL Multiphysics, using the general PDE option. The model could predict the experimental moisture and oil content data with reasonable accuracy. Simulations indicated that most physical processes attain a steady state in the first 20 sec. Thus, in the industry, energy can be saved by reducing frying time from 60 sec to 20 sec. The rate of moisture loss and oil uptake was found to be directly related to the pressure development, evaporation rate and frying temperature. Using fluid distribution, pressure development, temperature distribution and mechanical changes, physical insights about the transport mechanisms during frying were obtained.