Numerical prediction of temperature distribution and measurement of temperature in a high hydrostatic pressure food processor

Numerical simulation of temperature distribution in the pressurizing medium (water) during high hydrostatic pressure processing was carried out at different initial temperatures. Numerically predicted variations of temperature with time within the pressurizing medium were compared with the experimental results. The experimental data were corrected for the lag between the true temperature and the temperature measured by the thermocouples. A good agreement between numerically predicted and corrected experimental data was obtained when pressurization was started at initial temperature of 298.15 K, whereas some disagreement was observed at higher initial temperatures. The disagreement was attributed to the water addition to the vessel during pressurization which was not included in numerical simulation. A simple enthalpy balance was used to correct the numerically predicted temperatures, which led to better agreement. The numerical simulation enabled us to evaluate the process in terms of temperature uniformity inside the vessel. The results showed that the conjugate conduction and the natural convection heat transfer at the vessel wall affected the temperature distribution. The temperature non-uniformity increased with increasing initial temperature. The understanding of temperature uniformity during the high pressure process is important for uniform inactivation of microorganisms, enzymes, and particularly spores for which high pressure-high temperature combination is needed.