Numerical simulation of heat and mass transfer during heating and cooling parts of canned‐green‐olive pasteurization

Abstract

AbstractSimultaneous modeling of heat and mass transfer was applied in a cylindrical geometry through computational fluid dynamic (CFD). Two‐dimensional equations of mass, momentum and energy conservation were solved using finite elements method. The meshes were 7,882 triangular elements where 1,056 of them were in boundaries. The simulation was solved for a metal can filled with olives (Conservolea CV) and a 6% acid‐brine. Constant thermophysical properties of fluid remained static over the processing period except for the viscosity (temperature dependent) and density (in buoyancy term). The comparison criteria, between the predicted and experimental figures, using to evaluate goodness of fit, namely the coefficient of correlation (r = .9933) and the root mean square error (RMSE = 3.6555) indicated that the model was valid. The warm‐low‐density fluid ascended through a thin boundary layer and exchanging the heat, at the top of the can, where it flowed downward through the pores between the olives. This natural convection displaced the Slowest Heating Zone (SHZ) towards the bottom of the can, and eventually stayed in a region that was about 10 ± 15% of the can height from the bottom. The inactivation time for the most‐heat‐resistant fungus (Monascus rubber) during the thermal processing of green olives at 100°C was 600 s based on SHZ. A comparison between heat transfer by conduction and conduction–convection showed that the rate of heat transfer in conduction–convection was much more than conduction, also the SHZ in conduction was displaced towards the top of the can.Practical ApplicationsComsol Multiphysic, was used in this research in order to predict temperature profile in olive pasteurized in a metal can so that the accurate location of cold point was evaluated and the process time can then be controlled to reduce overheating and nutritional reduction or under heating and safety problems. As the model was validated, all the model results would be accurate to use so that velocity pattern of the fluid was extracted and different assumptions of heat conduction also were considered. The importance of pasteurization in different industries and the significance of reducing energy consumption, reveal our research importance because the calculated‐process time was much lower than what is currently used in industry.