High-performance nonequilibrium-plasma magnetohydrodynamic electrical power generator using slightly divergent channel configuration: II. Experiment

Murakami, Tomoyuki; Okuno, Yoshihiro

doi:10.1088/0022-3727/41/12/125212

Cited by 15 publications

(6 citation statements)

References 31 publications

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“…During the MHD interaction, the electron temperature differs from the heavyparticle temperature so that the plasma is in a nonequilibrium state. The electron temperature is elevated above the heavyparticle temperature by Joule heating; also, the recombination rate for "hotter" electrons and "cooler" heavy particles is low compared with the rate for equal temperatures of electrons and ions [1], [2]. The present experimental result, 2-D (r − θ) plasma images, is obtained by using a disk-shaped convexly divergent MHD generator under a seed fraction of 10 × 10 −4 , a load resistance of 0.15 Ω, and an applied magnetic flux density of 4.0 T [3], [4].…”

Section: Index Terms-magnetohydrodynamic Power Generation Plasma Wavesmentioning

confidence: 99%

Transient Behavior of Magnetohydrodynamic Power-Generating Plasma

Murakami

Okuno

2011

IEEE Trans. Plasma Sci.

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We present the structure of a nonequilibrium cesium-seeded argon (Ar-Cs) plasma in a closed-cycle magnetohydrodynamic (MHD) electrical power generator driven by a shock-tunnel facility. The transitional behavior from an inflow phase to an MHD phase is visualized. In the inflow phase, the high-temperature Ar-Cs gas produced by shock-wave heating flows in a supersonic channel. In the MHD phase, the plasma is self-organized by MHD effects. At the same time, the enthalpy of a flow is extracted in the form of electricity via the MHD effects. Index Terms-Magnetohydrodynamic power generation, plasma waves.(CCMHD) electrical power generator, which is one of the most efficient energy-conversion devices, directly converts the enthalpy of a flow into electrical energy using a nonequilibrium plasma without rotating high-temperature parts. Therefore, the CCMHD generator has several advantages, namely, high upper limits to the temperature it can tolerate, a rapid response, and the ability to achieve high thermal efficiency and high power density.A shock tunnel supplies a high-enthalpy gas flow to a diskshaped supersonic MHD channel with a total gas temperature of 2200 K and a total gas pressure of 0.2 MPa. An inert gas, argon, seeded with a small amount of alkali-metal vapor, cesium (10-1000 ppm), is used as the working medium (a cesium-seeded argon (Ar-Cs) plasma). The Ar-Cs gas expands from a highly pressurized stagnation state to a supersonic state through the MHD channel (the gas flows in the radial (r) direction in a narrow gap between parallel disks), where an external magnet applies a steady magnetic flux in the height (z) direction. The motion of the conducting gas through the magnetic field gives rise to an electromotive force and a flow of current in accordance with the Faraday law of induction. An electromotive force of u × B induces a Faraday current in the azimuthal (θ) direction, and a radial Hall electric field is induced by the Hall effect (u is the flow velocity vector, and B is the magnetic flux density vector). During the MHD interaction, the electron temperature differs from the heavyparticle temperature so that the plasma is in a nonequilibrium Manuscript

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Section: Index Terms-magnetohydrodynamic Power Generation Plasma Wavesmentioning

confidence: 99%

Transient Behavior of Magnetohydrodynamic Power-Generating Plasma

Murakami

Okuno

2011

IEEE Trans. Plasma Sci.

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“…Figures 3(a) and (b) show schematic front (r-θ plane) and cross-sectional (r-z plane) views of the slightly divergent generator, respectively. The slightly divergent generator is used in the experiments (part II of this duology [7]). The upstream part of the generator serves as a supersonic nozzle.…”

Section: Numerical Modelling and Proceduresmentioning

confidence: 99%

“…where U e is the energy of electrons, u e is the velocity vector of electrons, p e is the pressure of electrons, T g is the static gas (heavy particles) temperature, m h is the mass of heavy particles and i is the ionization energy of inert gas atoms and seed atoms. In (7), the two-temperature model is adopted, and the radiation loss is neglected, since it is 2-3 orders of magnitude smaller than the loss due to collisions.…”

Section: Basic Equations and Operating Conditionsmentioning

confidence: 99%

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High-performance nonequilibrium-plasma magnetohydrodynamic electrical power generator using slightly divergent channel configuration: I. Calculation

Murakami¹,

Okuno²

2008

J. Phys. D: Appl. Phys.

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We describe quasi-three-dimensional numerical simulations of a high-performance nonequilibrium-plasma magnetohydrodynamic (MHD) electrical power generator using a slightly divergent configuration. The slightly divergent generator provides greater isentropic efficiency (IE) than a highly divergent generator when an identical enthalpy extraction ratio (EER) is obtained. The inherent feature of a small divergent geometry is clarified; MHD energy conversion is accompanied by less entropy production as well as less gas expansion. The orientation of the performance improvement on an IE–EER map is consistent with the theoretically predicted orientation, which is formulated using an algebraic method based on classical thermodynamic results for supersonic compressible fluid dynamics. The power-generating performance indicators, IE and EER, are clearly determined by modified magnetic flux density, that is, the square of magnetic flux density divided by total inflow pressure. A virtual operating condition for a practical closed-cycle MHD system is proposed considering the relationships between the applied magnetic flux density, the total inflow pressure and the total pressure gradient throughout the generator. This paper is the first part of a duology.

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“…Smith et al summarized more than 30 studies on magnetic nanoparticles in the past five years and believed that the field is trying to minimize the side effects of lubrication on healthy cells [4]. Murakami and Okuno heat the tubular metal implants in the magnetic fluid through the magnetic fluid, but only when the magnetic fluid tissue of the lesion is relatively regular [5]. Su et al confirmed that the warm moistening method above 42 °C had an obvious killing effect on human MHD cells (QBC939).…”

Section: Introductionmentioning

confidence: 99%

Device for Simulating Fluid Microgravity Environment Based on Magnetic Compensation Method and Research on Magnetic Fluid Lubrication Performance of Oil Film Bearing

Peng

Shangguan

Zhang

2022

Advances in Materials Science and Engineering

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At present, with the rapid development of the material market, the requirements of high performance and high precision of materials are increasingly exposed. Nanomagnetic fluid materials are more and more widely used in oil film bearings, but their compressive strength and performance are insufficient, which is difficult to meet the current requirements of material chemical properties. First of all, a device for simulating a microgravity environment with magnetic compensation is fabricated. Then, in the microgravity environment, according to the different proportions of magnetic solid particles, the base carrier liquid and the surfactant are mixed to produce nanomagnetic fluid and the nanomagnetic fluid with different composition proportions is prepared by adjusting the proportion of ferrous and ferric ions. Finally, the lubrication performance of oil film-bearing magnetic fluid with different composition ratios was tested. The results show that when the ratio of Fe2+ to Fe3+ is between 11 : 20 and 13 : 20, the MHD (magnetohydrodynamics) lubrication performance of oil film bearing is in the peak region. When the ratio is 3 : 5, the best lubrication performance can be achieved. When it is slightly higher than this ratio, the oxidation rate is accelerated due to more ferrous ions. Although it can have a good lubrication effect, it is easy to cause the overall fluidity of oil film-bearing magnetic fluid to deteriorate. Therefore, the oil film bearing nano-MHD with the ratio of 3 : 5 ferrous to ferric has the best lubrication performance in the microgravity environment simulated by magnetic compensation. Experiments have shown that when the magnetic fluid is heated in a magnetic field, the temperature gradient will cause the magnetization to change, which makes the magnetic force experienced by the liquid in each part different, causing convection. Therefore, by selecting the direction of the magnetic field and the heating surface, by applying an external magnetic field or promoting convection, or suppressing convection, convection in the opposite direction to the natural convection of gravity can also be realized. Moreover, magnetism can immediately promote high-temperature boiling, generate bubbles, and eliminate the generation of bubbles to promote heat transfer. With the above effects, the heat conduction between the heating wall and the liquid can be controlled, and its practical and potential application fields are very wide.

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High-performance nonequilibrium-plasma magnetohydrodynamic electrical power generator using slightly divergent channel configuration: II. Experiment

Cited by 15 publications

References 31 publications

Transient Behavior of Magnetohydrodynamic Power-Generating Plasma

Transient Behavior of Magnetohydrodynamic Power-Generating Plasma

High-performance nonequilibrium-plasma magnetohydrodynamic electrical power generator using slightly divergent channel configuration: I. Calculation

Device for Simulating Fluid Microgravity Environment Based on Magnetic Compensation Method and Research on Magnetic Fluid Lubrication Performance of Oil Film Bearing

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