Heat transfer and flow pattern during sterilization of liquid food packaged in glass jars

A.R. LESPINARD; P.R. SALGADO; R.H. MASCHERONI

Foz de Iguazú

Conferencia; International Conference of Agricultural Engineering; 2008

CIGR

ABSTRACT: In this work, transient temperature and fluid flow during natural convection heating of a cylindrical glass jar containing tomato puree is simulated. The equations for continuity, momentum and energy conservation for an axisymmetric case are solved numerically using the finite element method. In the model constant properties were assumed except for viscosity (temperature dependent), density and time-dependent external temperature (characteristic to low-capacity retorts). The simulation shows that the action of natural convection forces the slowest heating zone (SHZ) to migrate towards the bottom. Axial velocity, thickness of the ascending liquid zone and the height of the SHZ were lower than those previously found for canned foods and constant external temperature. Predicted temperatures calculated using the convective model were not validated satisfactorily by experimental results, but the conductive model provided accurate predictions. These results suggest that the conductive mode is the preponderant heat transfer mechanism in heating tomato puree. Predicted temperatures calculated using the convective model were not validated satisfactorily by experimental results, but the conductive model provided accurate predictions. These results suggest that the conductive mode is the preponderant heat transfer mechanism in heating tomato puree. Predicted temperatures calculated using the convective model were not validated satisfactorily by experimental results, but the conductive model provided accurate predictions. These results suggest that the conductive mode is the preponderant heat transfer mechanism in heating tomato puree. : In this work, transient temperature and fluid flow during natural convection heating of a cylindrical glass jar containing tomato puree is simulated. The equations for continuity, momentum and energy conservation for an axisymmetric case are solved numerically using the finite element method. In the model constant properties were assumed except for viscosity (temperature dependent), density and time-dependent external temperature (characteristic to low-capacity retorts). The simulation shows that the action of natural convection forces the slowest heating zone (SHZ) to migrate towards the bottom. Axial velocity, thickness of the ascending liquid zone and the height of the SHZ were lower than those previously found for canned foods and constant external temperature. Predicted temperatures calculated using the convective model were not validated satisfactorily by experimental results, but the conductive model provided accurate predictions. These results suggest that the conductive mode is the preponderant heat transfer mechanism in heating tomato puree. KEYWORDS: Heat Transfer, Flow Pattern, Computational Fluid Dynamics (CFD), Tomato Puree: Heat Transfer, Flow Pattern, Computational Fluid Dynamics (CFD), Tomato Puree