Generation of MV impulses
Improving the efficiency of pre-packed food processing using non-invasive systems will drastically reduce energy consumption, a game changer for the food industry.
Although effective, the present invasive PEF system used in food processing has a number of drawbacks. Heating of the processed liquid by internal currents is one such drawback and requires cooling resulting in a massive energy consumption. Additionally, existence of the metallic electrodes in contact with the liquid cause issues including hydrolysis, clogging of chunks, regular cleaning and replacement.
When a non-invasive technology is used, the problems mentioned above are eliminated. As a result, greater volumes can be processed with less energy consumption, about 1% of that required by the present invasive systems. The most important advantage of this non-invasive method is its application to other processes, not just liquid foods.
A 1 MV Tesla transformer has been designed, manufactured and assembled. The transformer powers a large water capacitor with almost 1 litre of water being stressed with an intense pulsed electric field between 100 kV/cm and 300 kV/cm. A 1 MV closing switch, operated with SF6 at a pressure above 10 bar is used as a crowbar, separating the water capacitor from the transformer. When the switch closes, the water capacitor, together with a 1 MV inductor, forms a high-frequency oscillating LC circuit greatly improving the efficiency of pulsed electric field processing. Laser based electro-optic Kerr effect diagnostic is used to measure the electric field generated inside the water capacitor.
In the home, the analogy between non-invasive PEF systems and the nowadays very popular microwave oven could be relevant. Before the introduction of the microwave oven, only radar technology used powerful microwave sources. Apart from the fact that such equipment was extremely costly, experts were extremely sceptical of home usage, especially by untrained people, of formidable powerful (about 1 kW) microwave equipment. The introduction of non-invasive PEF equipment in houses will certainly not happen overnight, but when it does it will reduce the amount of food thrown away and will perhaps be included in a complex refrigerating system with computers running the PEF from time to time to prolong the life of the product.
Bucur Novac - Professor of Pulsed Power
“This is a novel concept and, if successful, could be extremely important to the food and drink industry. It is high-risk research with spectacular potential. We look forward to the first experimental results.”