This chapter presents general aspects regarding the electromagnetic fieldElectromagnetic field in radio frequency and microwaves, the thermal field, mass problems in radio frequency drying, and the authors’ contributions to the numerical analysis of high frequency drying. The material used in numerical simulationsNumerical Simulation is wood. Wood temperatureTemperature control is very important due to cracks and loss of mechanical properties during drying. The properties of dielectric materials are very important when studying the interaction that takes place between the electromagnetic field energy and the material. The need to process and obtain products that meet market demands has led to the development of process modeling software that are aimed at simulating processes and physical phenomena as precisely and realistically as possible. In the research center (Center for Research and Technological Engineering in Electromagnetic Energy Conversion—CCITCEE) a Fortran software complex that couples electric, thermal, and mass and motion problems called FEM-BEM.3D-RF was developed. In the present study the drying processDrying process of wood was numerical simulated using FEM-BEM.3D-RF in radio frequency field and Comsol Multiphysics in microwave field.

In this study, a neural network model was developed and tested to predict the characteristics of a possible industrial wood processing based on electromagnetic technologies. The application presented in this paper is a drying process for a half-finished oak blanks exposed in a radiofrequency electromagnetic field. To develop the model of this process, MATLAB's Neural network toolbox was used. The drying process was simulated with the help of FEM-BEM.3D-RFmove _term_masa software and the simulation results were used then for the training of the proposed neural network. The trained neural network is effective to provide the process characteristics with good accuracy.

This paper presents a modeling process, using the 2D Flux software and an optimization process, based on the Response Surface Method, Central Composite Design, from the Minitab Statistical Software. In this paper, the induction heating in volume of a semi-finished product has been modeled, neglecting the end effect.

This paper addresses the concrete mode of using the energy of the microwave field in the drying process of wooden sticks used in the food industry. For the numerical analysis of the microwave field we used the COMSOL Multiphysics numerical modelling programme. The experimental measurements were performed using a multimode applicator. The aim of this paper is to present a study on the microwave field (MW) drying of wooden sticks. This method ensures significant reduction of drying times, obtaining quality products, preserving the original geometry and structure of the sticks.

This paper presents some aspects concerning the modeling of heating some moving oak blanks in a radiofrequency electromagnetic field, which has been coupled with an optimization method based on a statistical model. The Response Surface Method and Central Composite Design type of experiment have been employed.

The purpose of this optimization is the identification of optimal parameters for processing the workpiece (the OLC45 steel bar), using inductive heating in volume. Flux 9.3.2 software, in 2D plan, has been employed in order to perform numerical simulations, while Minitab software has been used to determine optimal parameters.

In this work, Flux 2D software has been used. It has been coupled with an experimental design method, in order to model the induction heating in volume of a half-finished product, neglecting end effects.

The paper approaches the problem of modeling the microwave heating process using Neural Networks. The Neural Network was trained using Matlab and Comsol Multiphysics software. Numerical simulations were made in Comsol Multiphysics, obtaining the necessary input and output data to train the Neural Network. The training was made using Adaptive Neural Network tool from Matlab software.

The main purpose of the study presented in the paper is to follow the evolution in time of the temperature computed in the dielectric material in the process of heating oak wood using radio frequency. Depending on different values of time and anode voltage the evolution in time of the temperature computed in the absorbent charge is being studied using Comsol Multiphysics software.

This paper describes some aspects concerning the analysis of the electromagnetic and the thermal field in a microwave field using Comsol Multiphysics. A dielectric piece of oak wood heated/dried in a multimode-type applicator, at the frequency of 2450 MHz is used as model for numerical application.

In the present study a design of experiments method was used to obtain the most suitable responses. The variables that occur in the optimization are the movement of a dielectric material on Oy and Oz axis of a waveguide and the microwave power. The responses refer to the thermal field distribution, the reflected power, dielectric's temperature and the absorbed power.

The main objective of our research was to develop a model using the numerical simulation software - Comsol Multiphysics for the drying process of wheat seeds. A number of simulations were made in order to analyze the increase of temperature calculated in the dielectric material, the electric field intensity and total absorbed power.

The present paper describes the optimization process of heating a dielectric material, inside a microwave applicator, using design of experiments. Based on the results achieved through optimization, experimental data were done using a microwave installation. The dielectric material used within the optimization process and experimental data is Fir wood, with initial humidity of 62%.

Microwave power of 0.4 W/g and 0.6 W/g was used to dry samples of Barley seeds. The samples were divided as follows: using the energy power with hot, cold or no air stream. The temperature in the mass of the seeds was noted every 30 seconds, during the period of drying (600 seconds. The succeed of the experiment was reflected through the germination rate.

The objective of this study is to analyze the heating/drying characteristics of oak planks in a microwave field. In order to be able to control the maximum temperature values during the experimentaldeterminations and to assess the time necessary for the heating/drying of oak planks, numerical modeling has been performed, using the commercial software Comsol Multiphysics. The experimental results were obtained at a frequency of 2.45 GHz in a multimode microwaveapplicator.

The paper presents the optimization of the dielectric position inside a microwave installation created for processing dielectric materials - seeds/granular products - using design of experiments (DOE) with the main purpose of making the power transfer towards the dielectric more effective. Running simulations for various input data with the commercial Comsol Multiphysics software and using the experimental methods available in the statistical and data analysis software Minitab, we intend to obtain the optimal position of the dielectric inside the applicator for certain specified conditions.

The aim of the present study was the optimization of the factors that interfere in the heating process of a dielectric material inside a microwave applicator. Because in the process of optimization choosing the factors and responses is very important, in order to make the best decision when establishing the input data, Analysis of Variance was used. The article includes design of experiments using Design Expertsoftware and numerical modeling made with Comsol Multiphysics software.

The paper presents a design of experiments technique for the optimization of a waveguide position. General full factorial design with 2 factors and 3 levels was used during the process of optimization, results of the numerical simulations made with ComsolMultiphysics being the input data for the experimental design. The results obtained revealed a uniform distribution of the thermal and electrical field, in conditions of imposed temperature values.

A full factorial design was coupled with numerical simulation in order to find the best position of the dielectric material inside the applicator. The considerate dielectric material processed in this study is leather. The design performed using Minitab software, took into account 3 factors with 3 different levels. In order to point out the thermal and electrical field values during the process were performednumerical computations using the Comsol Multiphysics software.

This paper presents the variation of lime essence wood humidity depending to the microwave generator power and also the importance of using the high frequencies techniques combined with the conventional technologies of electrical installations that are used for mixed drying microwave – air stream.