Eugeniusz Kurgan

Analysis of coupled electric and thermal field problems by boundary-element method

This paper presents a new application of the boundary-element method to analysis of coupled electric and thermal field problems in conducting bodies. A nonlinear dependence of electrical and thermal conductivities on temperature and potential is taken into account. This approach is based on Kirchhoffs transformation and numerical integration of domain terms.

Simulation of the electromagnetic field and temperature distribution in magnetic nanoparticles hyperthermia

In this article hyperthermia therapy of tumors by electromagnetic field in radio-frequency range is described. Electromagnetic fields are used to generate temperature distribution inside the tumor and in surrounding tissues. First equations allowing calculation of the magnetic field within human body in terms of magnetic vector potential A and under sinusoidal steady state are derived. Next Pennes bioheat equation in a human tissue under uniform material properties with respect to temperature T is solved. Heat generation is caused by Brown and Neel relaxation processes. Also power loss formula in ferrofluid is presented. At the and some numerical example is solved and influence of various particle parameters on generation power and temperature is discussed.

Distribution of the potential and current density in the electrode of the PEM fuel cell

Purpose – Distribution of the electric potential and current density in the electrode of the proton exchange membrane fuel cell.Design/methodology/approach – Multicomponent model based on Maxwell‐Stefan equations is used to formulate generalized Ficks law. Next, mass conservation laws for gas components and equation of continuity for current density vector are formulated.Findings – The problem is expressed by three non‐linear partial differential equations in total molar contraction of the gas mixture, oxygen and water vapor concentration describing multicomponent Maxwell‐Stefan mass transport and fourth equation for electric potential distribution. The final system of partial differential equations describing the problem is highly non‐linear and mutually coupled not only directly but also through the non‐linear boundary condition and is solved by finite element method.Research limitations/implications – There are some convergence problems for some sets of the material parameters. Only one part of the fu...

Mathematical Model of Gas Transport in Anisotropic Porous Electrode of the PEM Fuel Cell

In this paper a gas mixture model is developed to study anisotropic hydrogen and water vapour flow in anode of the PEM fuel cell. Dependence of the distribution of concentrations and fluxes of the of gas components in anisotropic porous layer is investigated. First full partial differential equations describing mass transport for permeability and diffusivity tensors based on Darcy’s and Fick’s laws are developed. Next this set of nonlinear equations together with appropriate nonlinear boundary conditions using finite element method was solved. At the end an illustrative example is given.

Mutual Forces Acting on Chains of Particles

This paper describes a method to determine mutual forces acting between dielectric particles, which form chains. The Maxwell stress tensor method together with finite element method are used. It is shown that particles placed in inhomogeneous field, because of dielectrophoretic forces acting between them, have a tendency to collect one by one giving in effect even long particles chains. In this article, Maxwell stress tensors are integrated over particle surfaces to give total mutual forces interacting between molecules.

Magnetophoretic placement of ferromagnetic nanoparticles in RF hyperthermia

This article presents a method of permanently placing ferromagnetic particles in the tumor region for the duration of the treatment. It is based on the phenomenon of magnetophoresis, that is, the influence of a magnetic field with a strongly variable gradient on magnetically induced magnetic moment of particle. The presented approach has a great importance in particle separation industry as well as in nanoparticle tumor targeting.

Cooling effects inside water-cooled inductors for magnetic fluid hyperthermia

The paper lists several well-known formulas for on-axis magnetic field inside ideal solenoid and compares them with the values obtained from the computer simulation of the actual water-cooled coil for magnetic fluid hyperthermia (MFH) purpose. Performed analysis of coupled electro-thermal problem using finite element method (FEM) may led to the estimation of impact of heat losses due to water cooling on temperature within a region of interest (ROI) for some important model parameters. It is shown that cold water circulating inside the copper windings cause significant cooling of such inductors. What is important, it enables convenient conditions for ferrofluid testing and reliable operation of temperature sensors placed inside helical coils.

Distribution of the protons flow in electrolyte of the PEM fuel cell

In this paper water management in proton exchange membrane (PEM) fuel cell is considered. First mass conservation law for water is applied. Next proton transport is described by the Nernst-Planck equation and liquid water convection velocity is eliminated by the Schlögl equation. Electro-osmotic drag coefficient is related to hydrogen index and experimentally determined swelling coefficient.

Comparative analysis between the 2D and 3D models of interstitial microwave hyperthermia

The aim of this study is the comparison of the 2D and 3D finite element time-dependent analysis for interstitial microwave hyperthermia treatment. The described method is based on microwave heating of pathologic human tissue using a thin coaxial-slot antenna placed invasively in the diseased tissue. The shown problem relies on the solving of coupled electromagnetic and thermal fields under the assumption of an axial symmetrical model. The wave equation in a sinusoidal steady state and the bioheat equation under a transient state condition are considered. The numerical calculations for the 2D and 3D models give consistent results with an acceptable level of relative error. Increasing the finite element mesh density for the refined 2D* model leads to a more accurate evaluation of the tissue temperature while reducing computation time.

Numerical analysis on cathodic protection of underground structures

The presented paper describes the principles of cathodic protection (CP) of underground tanks using the sacrificial anode as well as method of calculation of the potential, current density and polarization distribution on all sides metallic tanks buried underground. Differential equations with boundary conditions are developed and next solved by FEM in 2D and 3D cases. The main goal of this publication is the computation of such distribution of the external protecting electrodes where protected structure will not corrode and next the calculations in 2D and 3D were compared. The article shows that it is sufficient to use 2D analysis for which the speed of equations solution is significantly larger than in 3D space.