Energy efficiency of an Ohmic heating technology by fluid jet in food industrial process

Sami Ghnimi and Nicolas Flach-Malaspina, EDF-R&D, Department of Energy Efficiency and Industrial Processes, France
Jean-François Maingonnat, INRA-Laboratory of Food Process Engineering and Technology, France
Marlene Dresch, ADEME, Agency for Environment and Energy Management, France

Keywords

Ohmic heating, power supply, delay time, process control, energy efficiency measurement, system analysis

Abstract

Ohmic heating is a food processing operation in which heat is internally generated within foods by the passage of alternating electric current. The electrical power supplied to the Ohmic cell is critically dependant on the electrical conductivities of the foods being processed. A lot of information about this project is available. There is no information about the effect of power supply pulse parameters on the energy efficiency of the Ohmic heating process.

This paper reports experiments on the effect of duty cycle changes in power supply energy efficiency. The voltage and current measurements at high frequency were performed.

The results suggest that duty cycle (D) reduce energy efficiency of the Ohmic heating process, which varied from 65 % to 90 %. The energy efficiency of the power supply up to 90 % was obtained when the duty cycle exceed 0.8. A predictive model of the energetic efficiency of the power supply according to the duty cycle is given. Based on thermal balance, the energy efficiency of the Ohmic cell is close to 96 % and independent of pulse parameters, flowrate or fluid level inside the receptacle.