The Thermo-Egg: A Combined Novel Engineering and Reverse Logic Approach for Determining Temperatures at High Pressure

Abstract

High-pressure thermal (HPT) processing is a novel form of thermal processing targeted at achieving commercial sterilisation of foods. During HPT processing, the final heating is generated volumetrically within the food as a result of rapid compression to pressures usually at or above 600 MPa. While the pressure within the process vessel is uniformly distributed, non-uniform temperature distributions can develop as a result of differences in the temperatures of vessel components and incoming fluids, and compression heating properties of the materials involved in the process. Therefore, a reliable system for recording temperature profiles in different locations of the high-pressure vessel is needed to determine process performance. In this work, a purpose-designed pressure-resistant shell was engineered to protect a miniature temperature logger. The impact of the shell’s thermal mass was analysed, and a numerical software routine developed, accounting for the delay in temperature readings. The reverse logic software algorithm was able to predict temperatures outside the shell with high accuracy from the temperatures measured by the logger inside the shell. This system is expected to contribute to the development and commercialisation of HPT processing by providing the reliable temperature measurement data required for thermal process validation.