A numerical analysis of thermofluiddynamics in a high pressure processing unit using computational fluid dynamics
Natural convection heating within a three-dimensional cylinder filled with liquid in the first case and liquid-solid in the second case during sterilization is simulated. The computations domain was performed for a cylinder with a diameter of 37 mm and height of 300 mm, which is the same as those used in the high pressure unit “FOOD-LAB model S-FL-850-9-W” available at the Department of Chemical and Materials Engineering at the University of Auckland. Direct treatment of water at pressure level of 500 MPa and within a pressure holding phase of 600 s is considered. Pressure is assumed to rise from atmospheric pressure to the treatment pressure of 500 MPa. The governing equations for continuity, momentum and energy conservation are solved using a commercial Computational Fluid Dynamics (CFD) package (PHOENICS), version 3.5, which is based on a finite volume method of solution. Temperature and pressure profiles within the model liquid are predicted. The simulations show that the heat transfer process after completion of the compression process is mostly controlled by conduction, which is due to the small effect of natural convection.
Keywords: High pressure processing, CFD, Temperature distribution.