Calculation Of Current Density Distribution Research Articles

Advanced parametric model for analysis of the influence of channel cross section dimensions and clamping pressure on current density distribution in PEMFC

The design of the flow field and the channel cross section of a bipolar plate as well as the intrusion effect of gas diffusion layers due to clamping pressure can significantly influence the performance of a fuel cell. The land and channel areas at a channel cross section can have different boundary conditions due to compression, intrusion of gas diffusion layers and transport phenomena. Todayapplication engineers are faced with the challenge of finding advantageous overall solutions from this plurality of multi-criteria parameters. In this thesis, a model approach is presented which combines a fully parametric analytical-empirical intrusion model with a 1D fuel cell model. This allows the calculation of current density distributions at the channel cross section, taking into account clamping pressure, channel parameters and operating conditions. Depending on the operating points considered, the results show that the maximum current densities occur in different areas of the channel cross section. In addition, with regard to the clamping pressure current density optima can be determined. Using this model approach, in an early development process application engineers will be able to compare hundreds of variants in a reasonable short time and thus determine advantageous fuel cell designs.

INFLUENCE OF SKIN EFFECT ON THE CALCULATION OF BUSBAR SYSTEMS HAVING RECTANGULAR CROSS SECTION

One method for the calculation of current density distribution in a finite number of long parallel conductors, having rectangular cross section, is proposed in this paper. Numerical results aim to highlight the importance of the skin effect, which can be combined with the proximity effect. The method of superposition of these two effects was applied to the calculation of the electromagnetic field in electric power busbars systems. It has been shown that the skin effect has a much greater impact, especially when the conductors are thin and strong electric currents flow through them, so special attention is paid to its calculation. For numerical solution the integral equations are used. The function of current density is approximated by the finite functional series. This way leads to a very accurate solution with only two terms. Differential evolution method is applied for minimization of error function. To demonstrate the application of the proposed approach, numerical values for busbars are presented and compared with values obtained by using the finite elements method.

МОДЕЛЮВАННЯ ВПЛИВУ АМПЛІТУДНО-ЧАСОВИХ ПАРАМЕТРІВ ЕЛЕКТРИЧНИХ ІМПУЛЬСІВ НА ПРОЦЕСИ АНОДНОГО РОЗЧИНЕННЯ ПРИ ЕЛЕКТРОХІМІЧНІЙ ОБРОБЦІ ДРОТЯНИМ ЕЛЕКТРОДОМ

Combined technology of sequential use of electroerosive and electrochemical machining with wire electrode allows to obtain highquality surface and to form metal components with high accuracy, regardless of material strength and hardness. Pulsed current in electrochemical machining greatly increases process controllability. The paper provides mathematical model of mass transfer in nearanode diffusion layer. This, together with calculation of current density distribution for a scheme with cylindrical cathode and flat anode, gives reasonable choice of amplitude-time parameters of electrical impulses. Such approach provides maximal current efficiency and precise prediction of removed layer thickness of surface obtained by a moving wire electrode. Conducted experimental researches on approbation of calculated method have shown that theoretical calculations are well consistent with experimental data. Proposed method allows to increase efficiency of electrochemical surface finishingafter electroerosive cutting.

Optimization of Resistance Spot Welding Transformer Windings Using Analytical Successive Approximation and Differential Evolution

A welding transformer represents a vital part of a resistance spot welding (RSW) system. Therefore, it is essential to ensure minimum copper loss in the windings. This paper describes a single-objective optimization procedure, which includes searching for the minimum copper loss in RSW transformer windings in regard to the dimensions of the primary and secondary windings. Copper loss in windings is obtained using an improved analytical method of successive approximation, which enables the calculation of current density distribution in coils with rectangular conductors. Finally, the calculated optimum windings' dimensions are further used in a parametric numerical model with the finite element method to confirm the reduction of copper loss.

Magnetic resonance current density imaging using one component of magnetic flux density

Current density distribution generated inside a volume conductor by externally applied currents can be calculated by using spatial distribution of its magnetic flux density, . The imaging modality used to reconstruct images of the current density distribution is known as magnetic resonance current density imaging (MRCDI). In MRCDI, spatial distribution of the current‐induced magnetic flux density is measured on a magnetic resonance imaging (MRI) platform. Calculation of current density distribution from magnetic flux density measurements requires all three components of . As only the component of which is in parallel with the main field of the MRI system can be measured, rotation of the subject is necessary to be able to acquire all three components of for a given current injection pattern. Rotating the subject inside the magnet is not trivial even for small‐sized objects and remains as a strong limitation to clinical applicability of the technique. In this study, a novel MRCDI reconstruction algorithm using only one component of is proposed to eliminate the need for subject rotation. Reconstruction performance of the proposed algorithm is evaluated on numerical and experimental models. Images obtained by the proposed and the conventional MRCDI algorithms, which utilizes three components of , are compared.

Analysis Method for Magnetostatic Field Without Region Integration in the Electrostatic Field Domain

The magnetostatic analysis is important on the corrosion detection problems and the nondestructive inspection of the structures. Boundary element method is often used to the magnetostatic analysis conventionally because boundary element method does not require the discretization of the magnetostatic field domain and has an advantage for open domain problems. However, in case of the current density should be considered as the source of the magnetostatic field, the conventional method requires not only numerical calculation of current density distribution, but requires numerical region integration of this current distribution which has been calculated at discrete sample points. These two steps of discrete numerical calculation of 3D space increases computational time and loses the accuracy. In this paper, a new boundary integral method for analyzing magnetostatic field without the calculation and the integration of current density distribution in the electrostatic field domain which obeys Laplace equation is developed. The region integration of current density distribution is reduced to the infinite region integration of the fundamental solution using the derivative of the boundary integral equation for electrical potential field. Since the analytical calculation of the infinite region integration could be achieved, the accuracy and computational time are improved. In order to demonstrate the accuracy and efficiency of the present method, some example problems are solved, and compared with the conventional method. Present method is also applied to the practical electro-plating problem.

Current distribution in a chlor-alkali membrane cell: experimental study and modeling

Observations via a video camera of the behavior of the bubbles produced in a chlor-alkali membrane cell with parallel-plate electrodes during sodium chloride electrolysis allowed us to justify the use of 1D model for the calculation of current density distribution. Experimental current density measurements were determined using segmented electrode method. The modeling was done in the case of secondary distribution. It takes into account the effective conductivity of gas-liquid mixture. Solving the modified Laplace equation was undertaken using commercial finite element method software. The numerically computed curves and the experimental measurements are in a good agreement.

Numerical calculation of current density distributions in high temperature superconducting tapes with finite thickness in self field and external field

The current density distribution of high temperature superconducting (HTS) tapes is modeled for the combined case of an alternating self and applied magnetic field. This numerical analysis is based on the two-dimensional Poisson equation for the vector potential. A one-dimensional current ( z-direction) and a one-dimensional applied field ( y-direction) are assumed. The vector potential is rewritten into an equation of motion for the current density J( x,y,t). The model covers the finite thickness of the conductor and an n-power E–J relation. The magnetic field dependence of J c is also included in this E–J relation. A time-dependent two-dimensional current distribution that is influenced by the aspect ratio of the conductor and the material properties in E= f( J, B) is calculated numerically. The numerical results are compared with the experimental results for the AC loss of a tape driven by a transport current. Finally, a total AC loss factor is given for two cases in magnetic field direction, perpendicular and parallel to the conductor broad side.

Application of the boundary matching method to elliptic conductors

A boundary matching method for the calculation of current density distribution in a long conductor with arbitrary cross section is presented in another paper. An example is given here treating an elliptical cross section. Explicit expressions for the current density distribution and conductor internal impedance are obtained. The current density and impedance are evaluated for elliptic conductors with different ellipticity. Experimental and published data confirm the analysis.

Calculation of Current Density Distribution and Terminal Voltage for Bipolar Electrolyzers; Application to Chlorate Cells

Criterion equations are derived to enable the calculation of voltage and local current densities in one cell of a bipolar chlorate electrolyzer. For the cell system, expressions for current losses due to parasitic currents are derived for two models (with common bubble separator channel or with bubble separator channels for each cell). The calculation includes also the determination of the circulation rate of electrolyte in the cell system. Finally, the influence of specific parameters on the terminal voltage, parasitic currents, and circulation rate of electrolyte is discussed.

Flow electrolyzers. III. Calculation of current density distribution and of terminal voltage for nonisothermal flow electrolyzers

Flow electrolyzers. III. Calculation of current density distribution and of terminal voltage for nonisothermal flow electrolyzers