Numerical Simulation of Natural Convection Heating of Canned Thick Viscous Liquid Food Products

Sterilization of a thick viscous liquid food in a metal can sitting in an upright position and heated from the side wall (T_w= 394 K) only in a still retort was simulated. The liquid had temperature dependent viscosity but constant specific heat and thermal conductivity. Equations of mass, motion and energy conservation for an axisymmetric case were solved and plots of temperature, velocity and streamlines were provided for natural convection heating and isotherms compared with pure conduction contour plots. Results indicated that the natural convection moved the slowest heating point to the bottom center. The bottom of the can heated up slower than predicted by pure conduction heating. The magnitude of the axial velocity was found to be of the order of 10⁻⁵ m/sec which varied with time and position in the can.