Temperature runaway of microwave heated materials: Study and Control

AbstractThe behaviour of a material in a microwave field is di-rectly related to the temperature dependence of the imaginary part of the permittivity of a material. According to the conditions of thermal evacuation chosen, for example convection, its heating is either stable or unstable. For some materials, a critical temperature can be defined which represents an upper limit beyond which the heating is unstable whatever the convective heat transfers. The optimal conditions which can be obtained through the use of an automatic regulation of the heating are, as a consequence, determined. The microwave heating of EPDM rubber is treated as an example.