Prediction of the electric discharge occurrence under repetitive bipolar rectangular pulsed electric field <20 kV/cm

摘要

Pulsed Electric Field (PEF) is a newly developed food sterilization technology applying repetitive electric pulses to inactivate microorganisms and enzymes in liquid food. The evolution of bubbles and consequent electrical breakdown of the liquid treatment chamber have been a bottleneck of its industrial applications. Traditional theory of impulse breakdown cannot be applied to the PEF treatment since its discharge is greatly determined by the size of bubbles. The aim of this study is to clarify the bubbles' evolution characteristics under different pulse parameters and their impact on discharges. A high-precision bubble monitoring system, including a high speed camera was developed to study the behavior of micron-scale bubbles in treated liquids. Quantitative formulas between the bubble cross-sectional area with electric field intensity, pulse duration, and pulse repetition rate were obtained, and the dependence of discharge probability on the bubble area was proposed. Prediction formulas were developed to predict the average discharge time, which makes it possible to find the proper PEF processing time without discharges under given parameters and offer theoretical support to optimize pulse parameters in the PEF food treatment process. Published by AIP Publishing.