Research And Simulation Of High Voltage Pulsed Electric Field Sterilization System

Pulsed electric field (PEF) sterilization technology with its good effect, short time, low temperature, low energy consumption, no pollution and other advantages, has attracted more and more attention of researchers. PEF sterilization process is that the pulse voltage is applied to the treatment chamber, generating electric fields on food product for sterilization. In the whole process, the pulse waveform generated by a pulse generator, the electric field strength and the temperature distribution in the treatment chamber are the three key factors affecting the system sterilization efficacy and food quality. Therefore, this paper mainly aimed at the three factors, simulates the pulse generator and the processing chamber and researches the method to enhance the sterilization efficacy. It provides important theoretical basis for building PEF system by ourselves.For pulse waveform, according to the forming mechanism of square wave pulse, this paper uses"Simulink"to the modeling and simulation of main circuit of OSU-4L system, and analyzes the wiring inductance, leakage inductance of the transformer and a treatment chamber load on the effect of the waveform. The simulation and analysis results show that the main circuit of low inductance and the treatment chamber of low capacitance can produce better square waveform.In the PEF system working process, there are three physical fields in the treatment chamber, electric field, flow field and temperature field. This paper first builds a 3D model of the co-field treatment chamber, based on which develops a mathematical model of the three coupled fields according to the theory of the electric field, flow field and temperature field, and simulates the flow properties, temperature distribution of the liquid (0.2%Nacl solution) and electric field distribution in the treatment chamber under the conditions of pulse voltage V, pulse lengthτ, frequency f, flow rateμand temperature T. According to the results of simulation and analysis, this paper proposes parametric modeling method of optimization treatment chamber structure as the index to the electric field and the temperature field uniformity, and a tentative idea by increasing the flow velocity fluid to state that turbulence, to increase the temperature distribution uniformity.In order to optimize the treatment chamber structure, this paper uses" COMSOL With MATLAB" secondary development environment to design a 2D co-field treatment chamber simulation analysis software, which can carry on the simulation analysis of the co-field treatment chamber in the different structures and different system parameters. Through the comparative analysis of different structures by using the software, this paper gives the optimal treatment chamber structure and presents that the temperature uniformity is the first standard to optimize the structure of the treatment chamber. This paper also analyzes the laminar and turbulent flow temperature distribution in the same structure, and demonstrates that the turbulent flow temperature distribution is more uniform than the laminar flow temperature distribution.At last, according to the pilot scale PEF system design requirements (field intensity, treatment capacity, conductivity range), this paper gives the optimal parameters of the co-field treatment chamber by the simulation analysis and provides a theoretical basis for the treatment chamber design.