16th International Conference
on Microwave and High Frequency Heating

18-21 September 2017, Delft, The Netherlands
13:30   Microwave and high frequency material interaction (2)
Chair: Guido Sturm
13:30
15 mins
NONLINEAR DIELECTRIC BEHAVIOR STUDY OF CHEMICAL REACTIONS IN STRONG TIME HARMONIC ELECTRIC FILEDS
Tao Hong, Zhengming Tang, Huacheng Zhu, Kama Huang
Abstract: In the presence of a strong electric field, novel phenomena always happen in chemical reactions. However, the mechanism is still unknown. This paper studies the interactions between chemical reaction systems and strong time harmonic electric fields. Based on the theory of molecule reorientation, the modified Smoluchowski-Debye equation is expanded by the Legendre polynomials [1]. The general expression of polarization is derived by Picard’s method [2]. The nonlinear variation is also discussed through a simple isomerization reaction. The results show that the polarization process is similar to the process of damped oscillation. Meanwhile, the condition for which the result applies is also discussed.
13:45
15 mins
POLYMER-CERAMIC COMPOSITES AS MATERIALS WITH REQUIRED COMPLEX PERMITTIVITY
Sebastien Vaucher, Vadim Yakovlev, Hannah Yeung
Abstract: Many applications in microelectronics and microwave power engineering rely on dielectrics with particular dielectric properties [1-3]. This paper outlines an original approach to production of materials with required complex permittivity. The technique is based on an inverted power-law mixing rule model computing volume fractions in which three or more prime materials should be taken to get in the resulting homogeneous mixture the required dielectric properties. Functionality of the approach is demonstrated by production of composites from a polymer matrix (polymethyl methacrylate) and two inorganic fillers (silicon and alumina). The composites are made by mechanically mixing the powders and axially hot-pressing and cooling the mixture. Complex permittivity of the samples is measured by a split-post resonator method. Experimental data on dielectric properties of the samples help calibrate the technique; for the used powders, the Looyenga power-law model is found to be most adequate. In the produced samples, the target values of dielectric constant are reached with a higher precision than the ones of the loss factor; however, analysis of the production process and error propagation in the computations suggest that deviations of the resultant complex permittivity fall in the anticipated ranges. Features and issues of both computational and production parts of the technique are finally discussed.
14:00
15 mins
TEMPERATURE OF A DROP OF ELECTRICAL DIPOLES
Serge Lefeuvre, Olga Gomonova
Abstract: The underlying question of microwave heating is to physically understand why and how electrical energy is transformed into thermal energy. It is known that electrical charges, in a closed chamber, are in permanent movement said thermal agitation. A model has been settled in order to affect, by comparison with experimental result, a temperature value linked to the mean kinetic energy of the dipoles and to see this kinetic energy increasing under the action of an applied electric field.