Electric Field Strength

The effects of both the electric and flow parameters on the lethality and energy efficiency of a pulsed electric fields (PEF) treatment were studied. An experimental plan was designed in order to study the microbial inactivation of Saccharomyces cerevisiae and Escherichia coli cells inoculated in a buffer solution. The following process parameters were taken into consideration: electric field strength (13-30 kV/cm), total specific energy input (20-110 J/mL), flow rate of the processed stream (1-4 L/h) and number of passes through the chamber (up to 5).

This paper discusses the applicability of a hybrid method which combines the Method of Moments (MOM) and the multiconductor transmission line (MTL) equations on modern day PCB-layout. A necessary component of the developed hybrid method is the distinction of the layout structures into structures which can be handled by MTL, structures which must be calculated by MOM and the detection of coupling paths. The developed distinction algorithm is based on appropriate rules and the estimation of computation error due to ignoring coupling paths. The coupling between structures described by the two methods is taken into account by an iterative algorithm and the help of an integral equation for the electrical field strength. The comparison of measurements with results of the hybrid method exposes the applicability of the developed hybrid method.

An important component of the pulsed electric field (PEF) technology is the treatment chamber in which the food is exposed to high voltage pulses. Non-uniformity of the treatment, particularly with respect to the electric field distribution, is a common problem in continuous PEF treatment chambers. A previously developed and validated Multiphysics model of a pilot-scale PEF system with co-linear electrode configuration was simplified and embedded into an iterative algorithm, automatically modifying the model's treatment chamber geometry and dimensions, and evaluating the simulated process with respect to a set of performance indicators. The algorithm was capable of identifying configurations that were superior to the standard co-linear treatment chamber configuration. A 3D Multiphysics model with the identified geometrical properties was developed and a corresponding treatment chamber manufactured. The Multiphysics model was validated by comparing measured and predicted temperatures at various process conditions induced in NaCl solution and apple juice.