A Multiphysics Modelling Approach for Improving Treatment

8 An important component of the Pulsed Electric Field (PEF) technology is the 9 treatment chamber in which the food is exposed to high electric field pulses. A 10 detailed knowledge of the electric field strength and the induced temperature 11 distribution in the chamber is essential to achieve efficient and gentle pasteurisation. 12 Experimental determination of such distributions is extremely difficult. However, 13 numerical simulation of the fluid dynamics coupled with the electric and thermal fields 14 inside the treatment chamber can provide this information at high spatial resolution. 15 A previously developed and validated full 3D Multiphysics model, describing the flow 16 pattern, the electric field, and the temperature distributions in a pilot-scale PEF 17 treatment chamber with co-linear electrode configuration, was simplified to a 2D axis18 symmetrical model. This approximation allowed for a significant decrease in 19 computational demand and, therefore, to an increase in the rate of model solving. An 20 iterative algorithm was developed, which allows automatic modification of the electric 21 insulator geometry (i.e. the treatment zone), and solves and evaluates the models 22 with respect to electric field uniformity and treatment volume. As the pressure drop in 23 continuously operated flow through systems is highly relevant, this parameter was 24 also taken into consideration for the treatment chamber redesign. Thus, the 25 developed algorithm was capable of identifying insulator geometries that were 26 superior in electric field distribution to the current experimental system, while keeping 27 Draft manuscript: PEF treatment chamber optimisation Page 2 the pressure drop caused by decreasing insulator diameters low. A 3D Multiphysics 28 model of the improved PEF treatment chamber, incorporating the equations for 29 mass, momentum, energy and charge conservation was developed and validated by 30 means of fibre optic temperature measurements in the redesigned system. 31 32