Numerical simulation of transient temperature and velocity pro®les in a horizontal can during sterilization using computational ¯uid dynamics A.G. Abdul Ghani, M.M. Farid * , X.D. Chen Food Science and Process Engineering Group, Department of Chemical and Materials Engineering, The University of Auckland, Private Bag 92019, Auckland, New Zealand Received 29 September 2000; accepted 23 January 2001 Abstract In this work, sterilization of a canned liquid food carrot±orange soup) in a metal can lying horizontally and heated at 121°C from all sides is simulated for a 3-D geometry. Transient temperature, ¯ow pattern, and shapes of the slowest heating zone SHZ) during natural convection heating of canned liquid foods are predicted. The partial dierential equations describing the conser- vation of mass, momentum and energy conservation are solved numerically using a commercial computational ¯uid dynamics CFD)softwarePHOENICS),whichisbasedona®nite-volumemethodofanalysis.Thesimulationshowsthein¯uenceofnatural convectionontheliquid-¯owpatternandonthemovementoftheSHZ.TheactionofnaturalconvectionforcestheSHZtomigrate towards the bottom of the can as expected. The SHZ eventually stays in a region that is about 20±25% of the can height from the bottom.Thesecondary¯owformationanditseectontheshapeoftheSHZareevident.Theresultsofthisworkarecomparedwith those for vertical can. It shows faster heating in the vertical can, which is expected due to the enhancement of natural convection caused by its longer height. Ó 2001 Elsevier Science Ltd. All rights reserved. Keywords: CFD; Horizontal can 3-D); Temperature distribution; Velocity pro®le; Carrot±orange soup 1. Introduction Thermalprocessingoffoodshasbeenoneofthemost widely used methods for food preservation during the twentieth century and has contributed signi®cantly to the nutritional well-being of much of the world's pop- ulation Teixeira & Tucker, 1997). Two dierent meth- ods of conventional thermal processing are known, the asepticprocessinginwhichthefoodproductissterilized priortopackaging,andcanninginwhichtheproductis packed and then sterilized Barbosa-Canovas, Ma, & Barletta, 1997). The sterilization process not only extends the shelf- life of the food but also aects its nutritional quality such as vitamin content. One of the challenges to the food canning industry is to minimize these quality los- ses,meanwhileprovidinganadequateprocesstoachieve thedesireddegreeofsterility.Theoptimizationofsucha process is possible because of the strong temperature dependence of bacteria inactivation as compared to the rate of quality destruction due to the dierences in the value of the activation energy Lund, 1977). In the design of thermal sterilization process opera- tions,thetemperatureintheslowestheatingzoneSHZ) during the process must be known. Traditionally this temperature is measured using thermocouples. The placementofthermocouplestorecordthetemperatureat various positions in a container during heating disturbs the ¯ow patterns. Errors may occur by the presence of thermocouplewiresrestrictingthefreemovementofthe liquid Stoforos & Merson, 1990). Also, it is dicult to measure the temperature at the SHZ because this is a region,whichkeepsmovingduringtheheatingprogress. For this reason, there is a growing interest towards the use of mathematical models to predict the food temper- ature during the thermal treatment Teixeira, Dixon, Zahradnik, & Zinsmeister, 1969; Naveh, Kopelman, & P¯ug, 1983; Datta & Teixeira, 1987, 1988; Nicolai, Ver- boven,Scheerlinck,&DeBaerdemaeker,1998). There has been several studies on mathematical modeling and numerical simulation of can sterilization Journal of Food Engineering 51 2002) 77±83 www.elsevier.com/locate/jfoodeng * Corresponding author. Fax: +649-373-7463. E-mail address: m.farid@auckland.ac.nz M.M. Farid). 0260-8774/01/$ - see front matter Ó 2001 Elsevier Science Ltd. All rights reserved. PII:S0260-877401)00039-5