MHD Generator Research Articles

A novel thermoacoustically-driven liquid metal magnetohydrodynamic generator for future space power applications

The generation of electricity in space is a major issue for space exploration, and among the viable alternatives, nuclear power systems appear to present a particularly suitable solution, especially for deep space exploration. Recent developments in thermoacoustic engine and liquid metal magnetohydrodynamic (LMMHD) generator technologies have shown that thermoacoustically-driven LMMHD generators are a promising thermal-to-electrical converter option for space nuclear reactors. In order to improve the power density and capacity of current thermoacoustically-driven LMMHD generators, a novel three-stage looped thermoacoustically-driven LMMHD generator is proposed and investigated in this work. A numerical model of the integrated system including a lumped parameter sub-model for the LMMHD generator is developed and validated. Using this model, the effect of key geometric and operating parameters on the operation and performance of the proposed system are investigated numerically, and acoustic field distributions are presented. The results indicate that when the heat source and sink temperatures are 900 K and 300 K, respectively, a thermal-to-electric efficiency of 27.7% with a total electric power of 4750 W can be obtained at a load factor of 0.92. This work provides guidance for the design of similar systems and contributes to the development of a new thermal-to-electrical conversion technology for space applications.

Importance of induced magnetic field and exponential heat source on convective flow of Casson fluid in a micro-channel via AGM

The study of the natural convective flow of a fluid in the presence of an induced magnetic field has always been of considerable importance due to its many applications in various areas of science, technology, and industry, such as the operation of magnetohydrodynamic generators. This study addresses an analysis of exponential heat source and induced magnetic field on the second-class convection of Casson fluid in a microchannel. The flow is in a vertical microchannel organized by two vertical plates. The answer to governing equations has been grabbed for temperature field, induced magnetic field, and velocity via Akbari-Ganji's method (AGM). Nusselt number, skin friction coefficient, and current density are approximated. Graphs that describe the conclusion of influential physical variables on velocity, temperature, current density, induced magnetic field, and skin friction coefficient distributions are shown. Comparison of results with numerical method (Runge-Kutta-Fehlberg, RKF-45), homotopy perturbation method (HPM), and AGM confirms the accuracy of answers obtained with AGM.

Hall and Rotation Effects on Radiating and Reacting MHD Flow past an Accelerated Permeable Plate with Soret and Dufour Effects

This article investigates numerically the effects of Hall current and rotation effects on radiating and chemically reacting unsteady MHD natural convection flow past an accelerated infinite vertical permeable plate in the presence of Soret and Dufour effects. The dimensionless coupled non-linear governing partial differential equations of the problem are solved numerically by employing finite element method. The influence of various physical parameters influencing the flow on the primary velocity, secondary velocity, temperature and the species concentration are displayed graphically whilst the numerical results of the primary skin friction, secondary skin-friction, Nusselt number and the Sherwood number are presented in tabular form. Results reveals that magnetic parameter, radiation parameter and chemical reaction rate tends to depreciate both primary and secondary velocity components whilst Hall, Soret and Dufour effects have reverse trend. Rotation parameter tends to retard fluid flow in the primary flow direction and accelerate fluid flow in the secondary flow direction. Thermal boundary layer thickness decreases with increasing radiation parameter whilst the reverse trend is noticed with increasing Dufour effect. Thermal diffusion effect causes to improve concentration boundary layer thickness whilst chemical reaction rate has reverse impact. These parameters have similar effect on the primary and secondary skin-frictions whilst opposite effect was noticed on the Nusselt and Sherwood numbers. This model problem finds an important in engineering and industrial application such as MHD generators, food processing, heat exchangers devices and internal rotation rate of the sun.
 HIGHLIGHTS
 
 The problem investigate the effects of Hall current and rotation effects on radiating and reacting on unsteady magnetohydrodynamics (MHD) natural convection heat and mass transfer flow over an infinite vertical porous plate embedded in a uniform porous medium taking Soret and Dufour effects into account
 The resulting partial differential equations governing the fluid flow are solved numerically using the finite element method. In order to determine the effects of various pertinent parameters and to investigate the important flow features, the numerical calculations for fluid velocity, temperature and species concentration are computed and shown graphically whereas skin friction, Nusselt number and Sherwood number at the plate are evaluated and depicted in tabular form
 The model problem finds an important in engineering and industrial application
 
 GRAPHICAL ABSTRACT

Theoretical modeling of a vortex-type liquid metal MHD generator for energy harvesting applications

The use of liquid metals (LM) in energy harvesting is gaining attention due to their unique properties. The DC vortex magnetohydrodynamic (MHD) generator is a suitable and robust option among the different approaches in which LM can be used for energy scavenging. In this device, the LM is driven in a cylindrical chamber to produce a swirling flow, which interacts with an external magnetic field, inducing electric currents that can be extracted to power an external electric system. In turn, the electrical resistance of this system highly affects the dynamics of the flow and the electric variables. In this work, two analytical models for the total voltage, electric current, electric and fluid power are developed. One model considers an inviscid fluid performing a rigid solid rotation. The second model considers a real fluid, for which the velocity distribution is also determined. For this latter case, MHD induced effects are modeled. These solutions are also obtained in dimensionless form in terms of the interaction parameter, Reynolds number and Hartmann number. In addition, 2D and 3D numerical models were implemented. These models are compared with reported experimental results, obtaining a good qualitative and quantitative agreement (differences ⩽13.5%) with numerical and analytical results.

Effect of Xenon Seed on Performance of Pre-Ionized Inert Gas Plasma MHD Power Generator

Effect of Xenon Seed on Performance of Pre-Ionized Inert Gas Plasma MHD Power Generator

Three-Dimensional Analysis of the Influence of the Magnetic Flux Density on Minimum PR in a Faraday-Type MHD Channel

The magnetohydrodynamic (MHD) behavior and performance characteristic have been revealed by 3-D numerical simulation of the Faraday-type MHD generator. Numerical results show that the generator inlet–outlet pressure ratio (PR) will affect the plasma behaviors and generator performance in the channel. At high PR, the plasma flows at supersonic, and higher electric power [enthalpy extraction rate (EE)] can be obtained. However, at low PR, boundary layer separation occurs with deflected flow of velocity streamlines and vortex in the separated flow region, owing to the oblique shock wave. Therefore, there exists a minimum PR to maximize power generation performance. Under the strong MHD interaction, the Lorentz force causes the loss of Mach number and the increase of static pressure, but it can alleviate the effect of oblique shock for a lower PR. Furthermore, suppressing the boundary layer separation effect gradually evolves into a normal shock wave. When PR is higher, the thermoelectric conversion efficiency increases, and then a weak shock wave will be generated in the channel, which will propagate upstream and evolve into a normal shock wave. Consequently, under a higher magnetic flux density, the minimum PR can be effectively reduced, and the best generator performance can be obtained. In addition, an “ <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$M$ </tex-math></inline-formula> ”-shaped velocity profile will be generated due to the significantly increased MHD interaction. The results calculated in the present simulation are valuable and important for setting working gas conditions and evaluating generator performance.

High Temperature Corrosion Stability of Ceramic Materials for Magnetohydrodynamic Generators

Abstract Corrosion by alkali metals and their compounds poses a significant challenge to the long-term material stability and service life for both metal alloys and ceramics at high operating temperatures. Chemical reactivity between alkali metals and materials underlie numerous industry challenges ranging from fireside corrosion in biomass-fired boilers to reaction with silica-based refractory ceramics in glass furnaces. The problem is particularly significant in magnetohydrodynamic (MHD) generators, where potassium or cesium compounds are introduced to improve the electrical conductivity of the working fluid. Thus, resistance to attack by alkali metal vapor is an important consideration in the selection and fabrication of ceramic electrodes and insulators for MHD generators. We evaluated several refractory ceramics to assess phase stability and known reactions with potassium and its compounds at high temperatures (T &amp;gt; 1,200 °C). Refractory ceramics were tested for potassium vapor corrosion using a modified ASTM standard test method with in situ monitoring of gas composition. Unlike other materials, the magnesia (MgO) and ceria (CeO2) samples did not exhibit corrosion, and no phase or mass changes were observed. This indicates that CeO2 and MgO could exhibit long lifetimes as plasma facing components in MHD generators. Ultimately, this development provides valuable data in evaluating critical materials performance issues that can attest to the viability of high temperature direct fired MHD generator applications.

Heat transfer analysis and entropy generation in the nanofluids composed by Aluminum and [formula omitted] Aluminum oxides nanoparticles

A porous rotating disk is used to study the second law of thermodynamics in relation to an electrically conducting, incompressible γ− alumina nanofluid. An external uniform vertical magnetic field. Base fluids are ethylene glycol and water. Alumina nanofluids make use of the experimentally derived viscosity and thermal conductivity models, as well as Brinkman viscosity and Maxwell's thermal conductivity models. Nuclear propulsion space vehicles can use the results of this research in rotating magnetohydrodynamic (MHD) energy generators and also thermal conversion processes. With shooting approach, fourth order Runge–Kutta method is used to solve the governing boundary layer equations numerically. The entropy generation equation can be obtained from the velocity and temperature gradients, respectively. There is a high level of agreement between the current study's findings and those of previously published studies. Using geometric and physical flow field-dependent parameters, this equation is nondimensional. Researchers have discovered that there are three types of velocity profiles that can be obtained: radial (or circumferential) velocity profiles, and tangential velocity profiles (radial velocity profiles). The influence of nanofluid type on fluid velocity, temperature, entropy generation, Bejan number, skin friction coefficient, and Nusselt number has been investigated. The same nanoparticles are expected to behave differently in temperature profiles with water and ethylene glycol. As well as demonstrating the potential of using magnetic rotating disk motors in revolutionary nuclear space propulsion engines, this model is valuable for increasing heat transfer in renewable energy systems and industrial thermal management.

Integration of MHD System to The Gas Turbine and The Steam Turbine Power Plant: A Brief Review

Electrical energy generation is essential for the survival of the modern society. Fossil fuels are limited and create pollution. Also the conventional power generation systems using fossil fuel have lesser efficiency due to higher amount of losses in different sections of the plants. The Magnetohydrodynamic (MHD) is found as a nonconventional energy generation system which has the capability to enhance the thermal power plant efficiency significantly. The MHD is a direct energy conversion system that describes the interactions of a magnetic field and an electrically conductive fluid to produce electrical power. The system is simple and it avoids the difficulty of choosing a rotating turbine or engine and massive number of complex calculations. The high temperature tolerable materials can be used in the system due to the exponential development of material science. In MHD system, energy of plasma or ionized gas is directly converted into electric power. The conversion process of the system is based on the principle of Faraday’s Laws of electromagnetic induction and fluid dynamics. The MHD generator uses hot conductive ionized gas or plasma as the moving conductor whereas in the mechanical dynamo, in contrast, uses the motion of mechanical devices to accomplish this. Seeding materials such as potassium carbonate, potassium sulphates are used to enhance the conductivity of the ionized gas. The focus of the present study is to investigate alternative methods through which an MHD power generator can be coupled to the existing gas turbine and steam plants. In doing so, the thermal cycle efficiency of these conventional plants can be improved. A case study is also presented to calculate the power output and efficiency in a simple way.

Исследование процессов в генераторе плазмы импульсного МГД-генератора на комбинированном пиротехническом топливе

This paper presents the results of numerical simulation of the processes in a two-chamber plasma generator of the pulsed MHD generator running on combustion products of a combined pyrotechnic fuel with afterburning in air oxygen. A mixture of Mg powder (a fuel) and KNO3 powder (an oxidizer and a source of the easily ionized additive) is chosen as a pyrotechnic fuel. The considered plasma generator includes a gas generator and an afterburner. Multicomponent combustion products of the selected pyrotechnic fuel contain solid particles of MgO and gaseous Mg. Within the afterburner, the unburnt Mg is burned up in the presence of air oxygen, forming MgO liquid particles. The proposed mathematical model allows one to numerically investigate all the processes occurring in a plasma generator of an MHD generator with an afterburner and to obtain the required data for determining the shape of the accelerating nozzle and the relevant parameters for calculations in the MHD channel.

Thermoelectrokinetic phenomena in the convective plasma zone of the Sun and stars

The study shows that electromagnetic phenomena in the convective plasma zone of the Sun and stars and the local magnetic field near the Sun’s surface are caused not only by the magnetohydrodynamic dynamo mechanism (Krause, Rädler 1980; Moffatt 1978; Morozov 2006), but also by the phenomena that have relatively recently become the focus of research, i. e., thermoelectrokinetic phenomena in the viscous electrically conductive medium in the presence of a temperature gradient (Grabov 2003; 2005a; 2005b; Prigogine, Nicolis 1977). The results of physical modelling and quantitative estimates show that thermoelectrokinetic currents can create primary magnetic fields of approximately B ≅ 103 Gs in the convective plasma zone of the Sun and stars.

A Novel Stochastic Framework for the MHD Generator in Ocean

This work aims to study the nonlinear ordinary differential equations (ODEs) system of magnetohydrodynamic (MHD) past over an inclined plate using Levenberg-Marquardt backpropagation neural networks (LMBNNs). The stochastic procedures LMBNNs are provided with three categories of sample statistics, testing, training, and verification. The nonlinear MHD system past over an inclined plate is divided into three profiles, dimensionless momentum, species (salinity), and energy (heat) conservations. The data is applied 15%, 10%, and 75% for validation, testing, and training to solve the nonlinear system of MHD past over an inclined plate. A reference data set is designed to compare the obtained and proposed solutions for the MHD system. The plots of the absolute error (AE) are provided to check the accuracy and precision of the considered nonlinear system of MHD. The obtained numerical solutions of the nonlinear magnetohydrodynamic system have been considered to reduce the mean square error (MSE). For the capability, dependability, and aptitude of the stochastic LMBNNs procedure, the numerical performances are provided to authenticate the relative arrangements of MSE, error histograms (EHs), state transitions (STs), correlation, and regression.

Performance analysis of an inert gas plasma Faraday-type MHD generator by coupling thermodynamic equilibrium ionization model with UDF functions of Fluent

Performance analysis of an inert gas plasma Faraday-type MHD generator by coupling thermodynamic equilibrium ionization model with UDF functions of Fluent

A liquid metal MHD vortex generator for energy harvesting applications

Liquid metal (LM) technologies for energy harvesting are gaining attention due to their unique properties. An LM vortex magnetohydrodynamic generator is a suitable and robust option among different approaches used for energy harvesting. In this device, LM is driven into a cylindrical cavity to produce a swirling flow, interacting with an imposed axial magnetic field and inducing electric currents that can be extracted to power an external electrical system. However, to maximize the power output, the effect of the electrical resistance on the flow dynamics and electrical parameters must be evaluated. Here, an evaluation is carried out with both the commercial software COMSOL Multiphysics and a theoretical model, whose results are partially validated with the experimental data obtained from a device built for this purpose. In addition, the effect of the electrode size on the global electrical variables, such as voltage, current and electrical power, is investigated numerically. Figs 5, Refs 9.

Design optimization of a disk magnetohydrodynamic generator based on the genetic algorithm

Design optimization of a disk magnetohydrodynamic generator based on the genetic algorithm

Numerical study of hybrid nanofluid flow and heat transfer on a stretching sheet with MHD and heat generation effects

AbstractThe key goals of this manuscript are (i) to investigate the heat transfer and unsteady flow properties of a viscous hybrid nanofluid on a stretching sheet having nonzero slot velocity, and (ii) to examine the impacts of magnetic field parameter, stretching parameter, nanoparticle volume fraction, and heat generation parameter on the Nusselt number and skin friction coefficient numerically. The Tiwari‐Das nanofluid model is used. The mathematical (PDEs) equations controlling border layer flow and heat transfer are resolved by applying a numerical finite‐difference technique in the Crank Nicolson style. For the validation process, the analytical solution is established using the Laplace transform technique and is compared with the numerical solution for a particular case and found to be in superb agreement.

Space Thermoacoustic Radioisotopic Power System, SpaceTRIPS: The Magnetohydrodynamic Generator

Electricity production is a major problem for deep space exploration. The possibility of using radioisotope elements with a very long life as an energy source was investigated in the framework of an EU project “SpaceTRIPS”. For this, a two-stage system was tested, the first in which thermal energy is converted into mechanical energy by means of a thermoacoustic process, and the second where mechanical energy is converted into electrical energy by means of a magnetohydrodynamic generator (MHD). The aim of the present study is to develop an analytical model of the MHD generator. A one-dimensional model is developed and presented that allows us to evaluate the behavior of the device as regards both electromagnetic and fluid-dynamic aspects, and consequently to determine the characteristic values of efficiency and power.

Parallel finite volume simulation of the spherical shell dynamo with pseudo-vacuum magnetic boundary conditions

In this paper, we study the parallel simulation of the magnetohydrodynamic (MHD) dynamo in a rapidly rotating spherical shell with pseudo-vacuum magnetic boundary conditions. A second-order finite volume scheme based on a collocated quasi-uniform cubed-sphere grid is applied to the spatial discretization of the MHD dynamo equations. To ensure the solenoidal condition of the magnetic field, we adopt a widely-used approach whereby a pseudo-pressure is introduced into the induction equation. The temporal integration is split by a second-order approximate factorization approach, resulting in two linear algebraic systems both solved by a preconditioned Krylov subspace iterative method. A multi-level restricted additive Schwarz preconditioner based on domain decomposition and multigrid method is then designed to improve the efficiency and scalability. Accurate numerical solutions of two benchmark cases are obtained with our code, comparable to the existing local method results. Several large-scale tests performed on the Sunway TaihuLight supercomputer show good strong and weak scalabilities and a noticeable improvement from the multi-level preconditioner with up to 10368 processor cores.

Multiparameter approach in the deep geoelectrics

The main provisions of geoelectrics are described, the importance of taking into account the ambiguity of its inverse problem is emphasized. Three main methods of deep geoelectrics which use natural fields of ionospheric-magnetospheric origin are considered: geomagnetic deep sounding (GDS), magnetotelluric sounding (MTS), and magnetovariational profiling (MVP). The response functions of each method are described. Each response function carries its own specific information about some parameters of the studied object and is characterized by the degree of reliability of the information about the object extracted from it. For example, the most reliable information about electrical conductivity anomalies (if any in the study area) is contained in the MVP response functions. The horizontal tensor of the anomalous field contains information about the electrical conductivity under the observation point, and the tipper (induction vector) contains information from the surrounding areas. In general, MVP information is less susceptible to distortions than MTS information and deserves more trust. Artificial field sources in deep geoelectrics are rarely used due to their high cost. Since 1970, two powerful sources created for other purposes arised on the Kola Peninsula and were used for deep sounding. In the center of these studies found themself young talented geologist-geophysicist and organizer of major projects AbdulkhaiAzimovichZhamaletdinov. The «Khibiny» project with an MHD generator and an ultra-deep well as one of the objects of the study, the «Zeus» low-frequency emitter, the signals of which were recorded in China at a distance of 7000 km, and a number of projects conceived and organized by Zhamaletdinov and executed under his leadership: «Volgograd-Donbass» (1979, 1986), experiments «PHOENIX» (2007, 2009, 2014, 2019) and others. At the same time, methods of interpretation were developed for sounding with artificial EM sources and new response functions were obtained which make it possible to «see» the object of research in a new way. This experience must be preserved, generalized, improved and used, for example as follows. In the area of modern synchronous multipoint MTS-MVP survey, a controlled source composed of two grounded lines emits strong current (harmonics at fixed frequencies and/or pulses) which signal will be recorded by survey instruments during night-time sessions.

To on-board MHD power generation

The electric power generation in on-board MHD generator is considered under conditions of vehicle’s flight in Earth atmosphere. The physical and computational model of on-board MHD power generation is presented. It is shown that electric power of order of 18 – 20 MW (or ∼ 100 W/cm3) can be extracted in ordinary Faraday-type segmented MHD generator. This high level of electric power is achieved at magnetic field about 0.3 – 0.4 tesla and constitutes nearly 9.5% of total enthalpy flux. The main factor limiting the rise of extracted power is a stall of flow due to MHD deceleration.