Electrothermics

I.1. Principle

Induction heating is a technique that can heat a material without direct contact with the electrical energy source. It consists of placing the object to be heated in a time-varying electromagnetic field and dissipating the energy induced inside the object as heat [DEV 00] (Figure I.1). It is appropriate for materials that are electrical conductors or semiconductors. It is used for many thermal processes, especially for the fusion or thermal treatment of metals [DEV 00].

Induction heating is based on four physical phenomena:

– creating an electromagnetic field using a solenoid with an electric field as described by Ampère’s law;

– electromagnetic induction, as expressed by the Faraday–Lenz law;

– heat production by Joule effect; and

– heat diffusion by conduction, as expressed by Fourier’s law.

In their differential form, these laws are expressed by the Maxwell equations and the heat transfer equation.

Figure I.1. Induction installation schematic