Search results

The purpose of the research was to develop a method for the determination of temperature characteristics of thermal diffusivity and specific heat on a single and the same stand, powered from an inverter for induction heating. Determination of the thermal diffusivity has been based on the idea of the pulse method. Searched solutions allowed to reduce inaccuracy of the pulse method when such an unusual source of pulse of energy is used.

Coupled electromagnetic and thermal calculations were carried out to verify proposed methods for estimating thermal properties of an induction heated charge. Presented methods were applied into a real laboratory stand and they were examined experimentally.

Achieved results of calculations allow to estimate thermal properties of the induction heated charge with 2 and 5 per cent of uncertainty, respectively, for heat capacity and thermal diffusivity. It gives possibility to use results as an input for further proceedings connected with estimation of electrical parameters in a more complex system.

Presented methods of estimating thermal properties of the induction heated charge were verified experimentally on a dedicated laboratory stand. It gives a practical possibility to implement previously established assumptions and examine them. This is a significant step toward the construction of an easy-to-use device for a comprehensive determination of material parameters of metals directly in the heat treatment plant.

This study presents a trial of implementation of induction heating as a source of energy in the impulse method for estimation of thermal properties of the material. Additionally, it presents a process of improving results achieved with the flash methods which were presented in previous papers. The method of estimation of specific heat which uses induction heating as the heat source was presented too.

The purpose of this paper is to investigate the efficiency of indirect determining of the thermal and electrical material characteristics of induction heated charges.

In the paper, the indirect method based on comparing the experimental and simulation results of temperature distribution has been considered. An influence of the type of the optimization techniques and the objective function form on its effectiveness was analysed. The experimental stand used in the described method was presented too.

The method of indirect determining of material characteristics can contribute to correcting the accuracy of the simulation of the induction heating systems. Its main problem is however the explicitness of determination of the material properties. It can be reduced by initial estimation of material characteristics, which can be made on the same experimental stand.

The paper describes how the response surface methodology was tested in indirect method of determining the thermal and electrical material characteristics.

The paper presents the results of computer simulation of the process of induction heating with series transistor inverter. In the simulation of induction heating system the coupled harmonic electromagnetic and transient thermal fields were combined with the simulated real energy source. As a source, the transistor bridge inverter with series resonant circuit was applied. The source parameters (inductor voltage and frequency) depend on the load parameters obtained by numerical calculations of the coupled fields. As the examples, the induction heating before hardening of stationary cylindrical workpiece and of the moving flat workpiece were considered. The simulation results were compared with these obtained in the simulation at constant inductor voltage and frequency.

The investigation of the efficiency of optimisation technique based on approximation of objective function by multiquadric (MQ) function, used for induction heating devices was the aim of the paper.

The optimisation package based on Matlab language and using Flux2D commercial program for calculation of electromagnetic and thermal fields was built. It allows the use of different optimisation techniques for induction heating devices, e.g. based on MQ function approximation. In the paper two algorithms of approximated points generating have been tested.

The efficiency of MQ optimisation method strongly depends on the applied algorithm of approximated point generating. To ensure high efficiency of MQ optimisation method, the stochastic element of the algorithm of approximated point generating should have a significant role.

The efficiency of elaborated algorithms of MQ function approximated point generating should be proved in other applications.

The efficient optimisation technique of induction heating devices has been proposed.

The two new algorithms for generation of MQ function approximated points have been proposed. The paper could be useful for designers of induction heating devices.