A comparative study on the performance of three treatment chamber designs for radio frequency electric field processing

- Three treatment chamber designs for radio frequency electric field process were assessed by Multiphysics modelling.
- Parallel-plate chamber resulted as the most energy-efficient design compared to Steinmetz and co-linear.
- Co-linear and Steinmetz designs have pronounced flow recirculation-stagnation areas promoting the formation of hot spots.
- Excellent agreement between predicted results from Multiphysics model and experimental measurements.
- Microbial inactivation is independent of chamber geometry.

The performance of three different chamber designs: co-linear, Steinmetz and parallel-plate, for radio frequency electric field (RFEF) processing of liquid foods was evaluated and compared. The study was conducted via a computational model that predicted the electric field, flow, and temperature distribution in those three chambers. The parallel-plate, in spite of having the highest electric field peaks, exhibited not only the most uniform electric field distribution inside the treatment zone but also the most homogenously distributed velocity profile along with the lowest temperature increase and energy consumption. The model was validated by comparing the predicted and experimentally measured outlet temperatures. Experiments of E. coli inactivation were performed in all three chambers at a volumetrically averaged electric field strength of 13.2 kV cm−1, a treatment time of 500 μs and outlet temperatures in the range of 20-50 °C showing equal inactivation given the uncertainties of microbial population quantification methodology.

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