Measurement of Temperature Dependent Permittivity for Thin Material during Microwave Heating

The use of microwave heating to initiate combustion synthesis has been increasingly investigated in recent years because of its advantages over traditional methods. A simple mathematical model is used to model these experiments. The microwave power absorption term is modelled as the product of an Arrhenius reaction term with a function that decays exponentially with distance. The former represents the temperature-dependent absorption of the microwaves whereas the latter describes the penetration of the material by the microwaves. Combustion kinetics are modelled as a first-order Arrhenius reaction.

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Receding horizon H∞ guaranteed cost tracking control for microwave heating medium with temperature-dependent permittivity

ISA Transactions ◽

10.1016/j.isatra.2018.01.001 ◽

2018 ◽

Vol 73 ◽

pp. 249-256 ◽

Cited By ~ 4

Author(s):

Jiaqi Zhong ◽

Shan Liang ◽

Qingyu Xiong

Keyword(s):

Microwave Heating ◽

Tracking Control ◽

Temperature Dependent ◽

Receding Horizon ◽

Guaranteed Cost ◽

Heating Medium

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Coupled thermal-electromagnetic model for microwave heating of temperature-dependent dielectric media

IEEE Transactions on Plasma Science ◽

10.1109/27.772285 ◽

1999 ◽

Vol 27 (2) ◽

pp. 555-562 ◽

Cited By ~ 36

Author(s):

Y. Alpert ◽

E. Jerby

Keyword(s):

Microwave Heating ◽

Temperature Dependent ◽

Electromagnetic Model ◽

Dielectric Media

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Effects of Sample Shapes and Thickness on Distribution of Temperature inside the Mineral Ilmenite Due to Microwave Heating

Minerals ◽

10.3390/min10040382 ◽

2020 ◽

Vol 10 (4) ◽

pp. 382

Author(s):

Mas Irfan P. Hidayat ◽

Dian M. Felicia ◽

Ferdiansyah I. Rafandi ◽

Affiani Machmudah

Keyword(s):

Microwave Heating ◽

Maximum Temperature ◽

Thickness Variation ◽

Temperature Dependent ◽

Fe Method ◽

Slab Geometry ◽

Conservation Of Energy ◽

Good Trade ◽

Poynting Theorem ◽

Innovative Techniques

The study of interaction between microwave radiation and minerals is gaining increasing interest in the field of minerals and material processing. Further studies are, however, still required to deepen the understanding of such microwave heating mechanisms in order to develop innovative techniques for mineral treatment using microwave heating. In this paper, effects of sample shapes and thickness on the distribution of temperature inside the mineral ilmenite (FeTiO3) due to microwave heating were numerically studied using the finite element (FE) method. The analysis was carried out in such a way that the flux of microwave energy was converted into an equivalent amount of heat generation in the mineral through the Poynting theorem of conservation of energy for the electromagnetic field. In this study, as a first attempt, the cylinder and slab of ilmenite were modeled to be irradiated from top and bottom surfaces with the variation of cylinder and slab thicknesses. Temperature-dependent material properties of ilmenite were taken into account in the FE simulation. Corresponding boundary conditions were then applied accordingly to the cylinder and slab of ilmenite with comparable characteristic length. Numerical results showed that, in terms of temperature differences between locations having maximum and minimum temperatures, slab geometries tended to produce higher values in comparison to those of cylinder geometries with the thickness variation, while the profiles of temperature inside the ilmenite samples were similar for both geometries. For the same duration of microwave heating, the slab geometry, hence, induced greater non-uniformity of temperature inside the ilmenite. It was also observed that, for the ilmenite samples with thickness value greater than 1.5 cm, the hotspot locations were not in the center of the sample, but on the surface of sample. Moreover, from several thickness values considered in this study, the ilmenite sample with thickness value of 3 cm gave a good trade-off between the maximum temperature value attained and temperature differences inside the sample, for both geometries. Thus, the shape and thickness of ilmenite samples affect the effectiveness of microwave heating of ilmenite, in terms of maximum temperature attained, temperature differences, and uniformity of temperature.

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