(606e) Development of Pilot Scale Fluid Handling System with Energy Recovery for Pulsed Electric Field Processing

Previous pilot scale studies showed that pulsed electric field (PEF) combined with mild heating enhances the effectiveness of microbial inactivation and extends shelf life of foods. Particularly, the process sequence of PEF-PEF-Heating-Holding-Cooling-Filling provided longer shelf life than that of Heating-Holding-Cooling- PEF-Cooling-PEF- Cooling-Filling. Therefore, a new fluid handling system needs to be developed and evaluated. The objectives of this project were to (1) develop a fluid handling system with an energy recovery heat exchanger to accomplish the process sequence, and (2) investigate the energy efficiency of this system. The pilot scale fluid handling system built with a feed pump, PEF treatment chambers, a backpressure control regulator, holding tubes, an energy recovery heat exchanger, and a supplementary heat exchanger. The energy recovery heat exchanger was used to heat foods before PEF treatment and cool foods after the holding tubes. The OSU-5C pilot scale pulse generator provided high voltage pulses. Apple ciders were used for this study. Eight points of temperatures were recorded during the operation. Test conditions for this study: PEF field strength: 32, 26, 20 kV/cm; total treatment time: 44 ms; holding temperature: dependent on PEF field strength; holding time: 15 s; flow rate: 125 l/h; backpressure: 40 psi. The energy recovery heat exchanger efficiently heat the apple ciders before the PEF treatment and cool the apple cider after holding without external heat or cool supply source. In comparison to previous fluid handling system, the new system saved 1500 L city water for cooling, and 28 kW electricity for heating per one-hour operation. Enclosed figures and tables illustrated details of system confutations, temperature profiles, and calculations of energy consumption and efficiency. The fluid handling system significantly increased energy efficiency thus reduced the operational cost. This system also provided easier operation and better temperature control than old systems.