期刊名称：Association for Computing Machinery New Zealand Bulletin
印刷版ISSN：1176-9998
出版年度：2005
卷号：1
期号：2
出版社：New Zealand Chapter
摘要：Although CFD models have been applied since long time ago to different processing industries, it is only in recent years that they have been applied to food processing applications. A number of commercial software packages of practical use to the food industry have now become available, such as PHOENICS used in our simulations. CFD models can be of great use in a variety of food engineering applications. It can be used for predicting convection patterns in chillers or ovens, or determining the flow patterns of airborne microorganisms in a clean-room factory environment.The objective of this work is to analyze the process of thermal sterilization of liquid food in a three-dimensional pouch and to predict transient temperature, and concentrations of bacteria and vitamins profiles as heating progresses. The migration of the slowest heating zone during natural convection heating in a pouch heated from all sides was simulated and presented. The model liquid (carrot-orange soup) was assumed to have constant properties except for the viscosity (temperature dependent) and density (Boussinesq approximation). The governing equations of continuity, momentum and energy equations were solved numerically, together with that of bacteria and vitamins concentration, as expressed by a reaction kinetics model. A computational fluid dynamics (CFD) code PHOENICS was used, which is based on finite volume method of solution. The results of the simulations showed that, natural convection plays an important role in the heat transfer within the liquid food in pouch. The SHZ was found to migrate toward the bottom of the pouch into a region within 30-40% of the pouch height, closest to its deepest end. The profiles of the relative bacteria and different vitamin concentrations were also found from the simulation, which maybe used to optimize the industrial sterilization process with respect to sterilization temperature and time.
关键词：Temperature distribution ; Bacteria deactivation ; Vitamin destruction
