Effect of dimensions and geometry of co-field and co-linear pulsed electric field treatment chambers on electric field strength and energy utilisation

Approximations of the electric field strength and specific energy input of continuous pulsed electric field (PEF) systems often assume parallel plate configurations. However, it is known that actual electric field strengths and specific energy inputs can be significantly different from this simplistic approach. A systematic study of more than 150 dimensions and various insulator geometries of pilot-scale PEF treatment chambers with co-linear electrode configuration was performed. A reduction of the inner diameter of the insulator and its shape changes the distribution and (average) intensity of the electric field. Both, the average electric field strength of the PEF treatment zone and the actual specific energy input, were significantly lower than the expected values derived from dividing the applied voltage by the electrode gap. The difference between theoretical and actual values generally increased with increasing electrode radius and decreasing electrode gap. The relative ratios of theoretical electric field strength or specific energy input to actual (average) electric field strength or specific energy input showed a linear dependency on the ratio of electrode radius and gap. The determined relationships of specific energy input and treatment chamber dimensions and geometry were experimentally validated in four different PEF treatment chambers.