An efficient empirical model for microwave-induced average temperature of liquid cylindrical reactants.

Microwave-assisted chemical reactions have become very popular in preparative chemistry due to many advantages such as accelerated reaction rate, higher chemical yield and lower energy use. In dedicated equipment, however, the microwave units operate as "black boxes" keeping the role of the thermal effects in microwave-assisted chemical processes somewhat obscure. To address this issue, in this paper, we propose a simple mathematical model for computing microwave-induced temperature in a three-media cylindrical structure representing a core element of a typical microwave reactor with the reactant assumed to be stirred by convection flows.

Applicability study of classical and contemporary models for effective complex permittivity of metal powders.

Microwave thermal processing of metal powders has recently been a topic of a substantial interest; however, experimental data on the physical properties of mixtures involving metal particles are often unavailable. In this paper, we perform a systematic analysis of classical and contemporary models of complex permittivity of mixtures and discuss the use of these models for determining effective permittivity of dielectric matrices with metal inclusions. Results from various mixture and core-shell mixture models are compared to experimental data for a titanium/stearic acid mixture and a boron nitride/graphite mixture (both obtained through the original measurements), and for a tungsten/Teflon mixture (from literature).

Practical aspects of complex permittivity reconstruction with neural-network-controlled FDTD modeling of a two-port fixture.

The paper discusses characteristics of a new modeling-based technique for determining dielectric properties of materials. Complex permittivity is found with an optimization algorithm designed to match complex S-parameters obtained from measurements and from 3D FDTD simulation. The method is developed on a two-port (waveguide-type) fixture and deals with complex reflection and transmission characteristics at the frequency of interest.

CAD of efficient TMmn0 single-mode elliptical applicators with coaxial excitation.

This paper suggests computational and engineering approaches to designing single-mode elliptical applicators for thermal processing of cylindrical samples of relatively small diameters. Through a systematic computational experimentation employing a 3D conformal FDTD model, we show that stable and efficient excitation of even and odd TMo modes of elliptical waveguides can be achieved by appropriate placing of two (one active and one passive) coaxial probes extended in the longitudinal direction of the cavity of relatively small height and by choosing the dimensions of the cavity. Effects produced by cylindrical loads inserted in the electric field maxima of the applicators featuring even TM010, TM110, and TM210 modes are studied for materials with different dielectric constants and the loss factors.