Magnetohydrodynamic Electrical Power Research Articles

Fundamental Study of Radio-Frequency Preionization for Seed-Free Magnetohydrodynamic Electrical Power Generation

A fundamental study of radio-frequency preionization has been conducted as a preliminary step toward the application in a seed-free magnetohydrodynamic electrical power generator. Argon gas heated and pressured in a shock tunnel facility is accelerated to supersonic speeds in a straight cylindrical duct without applied magnetic field and is ionized by a radio-frequency electromagnetic field with an induction coil. The experimental results show that the discharge changes from E-mode to H-mode via unstable discharge with the increase in radio-frequency input power. This H-mode discharge generates a stable plasma in the supersonic flow. Two-dimensional numerical simulations show that the calculated static pressure and coil current agree with the experimental results. In the supersonic flow, the maximum Joule heating and ionization occur close to the duct wall because of the effect of the velocity boundary layer, and the plasma is almost attached to the wall. Conversely, in the subsonic flow, maximum Joule heating and ionization occur away from the duct wall. The power factor of discharge in the supersonic flow is higher than that of the discharge in the subsonic flow under the same input power conditions.

Magnetohydrodynamic electrical power generation using convexly divergent channel: I. Experimental demonstration

We describe shock-tunnel-based experiments carried out to evaluate a magnetohydrodynamic electrical power generator equipped with a convexly divergent supersonic channel. Two-dimensional structure of the streaming MHD plasma and the temporal behaviour of electron temperature are examined. The spatial profile of MHD power-generating plasma and the energy-conversion efficiency in the convexly divergent channel are compared with those from a linearly divergent channel. For an understanding of the basic scaling of the channel geometry modification effect, a convexity parameter is proposed. With this simple and fundamental scaling parameter, the dependence of plasma–fluid properties and energy-conversion efficiency on the channel convexity is quantitatively examined. The quality of MHD plasma and the generator performance are improved at the convexity parameter of 0.35 (a slight enhancement of the channel convexity) rather than at the convexity parameter of zero (no convexity or concavity). This paper is the first part of a duology.

Experiments and numerical simulations on high-density magnetohydrodynamic electrical power generation

We describe experiments and numerical simulations on high-density energy conversion using a compact closed-cycle magnetohydrodynamic electrical power generator, where shock-tube-based experiments and quasi-three-dimensional numerical simulations are fully coupled. The temporal plasma-fluid behavior, the one- and two-dimensional plasma-fluid structures, the enthalpy-entropy diagram, the Hall voltage-Hall current characteristics, and the quality of the energy conversion efficiency are investigated. The slightly divergent channel configuration, the application of high- and uniform-density magnetic flux to the entire generator, the high electrical conductivity, the symmetric plasma structure and stable plasma behavior, and the sufficient pressure gradient used to drive the fluid overcome the disadvantages of the generator due to its compactness, and markedly improve its energy conversion performance, namely, a power density of 0.76GW∕m3, an isentropic efficiency of 51%, and an enthalpy extraction ratio of 17.0%.

Radio-frequency power assistance on a compact magnetohydrodynamic electrical power generator under high-density magnetic flux

We describe the effect of radio-frequency (rf) electromagnetic field application on a compact magnetohydrodynamic (MHD) electrical power generator under high-density magnetic flux. The rf-power assistance improves the Hall potential profile and fluid flow structure, and rectifies large-scale plasma instability. These effects are vital for the compact MHD generator. With the aid of rf power, the power generation performance is significantly improved even under the low-plasma-stability condition for high-density magnetic flux.

High-density energy conversion using compact magnetohydrodynamic electrical power generator

We describe high-density energy conversion using a compact closed-cycle magnetohydrodynamic electrical power generator. The slightly divergent disk-shaped generator exhibits improved energy-conversion performance, in particular, a high power density of 0.76GW∕m3. The application of high- and uniform-density magnetic flux to the entire generator, the high electrical conductivity, the symmetric plasma structure and stable plasma behavior, and the sufficient pressure gradient used to drive the fluid contribute to the outstanding performance of the generator.

Pulse Detonation Magnetohydrodynamic Power

A series of laboratory-scale experiments were conducted to investigate the basic engineering performance characteristics of a pulse detonation-driven magnetohydrodynamic electric power generator. In these experiments, stoichiometric oxy-acetylene mixtures seeded with a cesium ‐hydroxide/methanol spray were detonated at atmospheric pressure in a 1-m-long tube having an i.d. of 2.54 cm. Experiments with a plasma diagnostic channel attached to the end of the tube cone rmed the attainment of detonation conditions (p2/p1 » 34 and D» 2400 m/s) and enabled the measurement of current density (» 2 A/cm 2) and electrical conductivity (» 6 mho/m) behind the detonation wave front. In a second set of experiments, a 30-cm-long continuous electrode Faraday channel, having a height of 2.54 cm and a width of 2.0 cm, was attached to the end of the tube using an area transition duct. The Faraday channel was placed inside a permanent magnet assembly having a nominal magnetic induction of 0.6 T, and the electrodes were connected to an active loading circuit to characterize power-extraction dependence on load impedance while also simulating higher effective magnetic induction. The experiments indicated peak power extraction at a load impedance between 5 and 10 X . The measured peak electrical energy density ranged from 10 to 10 3 J/m 3 when the effective magnetic induction was varied from 0.6 to 4.2 T. These results were in reasonable agreement with a simple electrodynamic model incorporating a correction for near-electrode potential losses. By scaling-up to a practical-size device, limiting the near-electrode potential drop to 10% of the induced potential, and optimizing seed-atomization characteristics, we anticipate a e ve- to tenfold increase in attainable electrical energy density.

Fuel Conservation and Applied Research

This article discusses the importance of generic applied research with the aim of encouraging both the technical and political support of a program that would be appropriate and useful for the common good. A number of past, present, and future examples of applied research efforts related to fuel conservation are described, and an institutionalization of the means by which such efforts can be organized and utilized for an effective long-term fuel conservation program are suggested. The role of applied research in conservation is described and used as an example to show what a well-organized applied research program can produce. The same approach can also contribute to the attainment of such national goals as reducing atmospheric pollution, increasing industrial productivity, conserving scarce materials and developing renewable sources of energy. The development and improvement of electrical power generation as an example of the past role of applied research is described. Current efforts in applied research such as ceramic gas-turbine components, magnetohydrodynamic electric power generation, fluidezied bed combustion, and supercritical airfoil are also described. The most significant opportunities for future successes appear to be in automotive technologies, specifically aerodynamic drag and tribology (the science of friction, lubrication and wear). The institutionalization of applied research is examined and it is noted that what is needed primarily is a mechanism for generating appropriate applied research topics. The classical function of federally supported R&D is to develop technologies whose eventual payoff is potentially high but which entails too much risk for prudent private sector investment. The chief mechanism for ensuring that the responsibilities of a national program for applied research are properly discharged is a national forum for program planning and review. Engineering societies it is noted can provide the effective institutional umbrellas for such a national forum.

Magnetohydrodynamic Electrical Power Generation (Report on the Fifth International Conference, Munich, Federal Republic of Germany 19-23 April 1971)

In the three years that have elapsed since the last Symposium on Magnetohydrodynamic (MHD) Electrical Power Generation, held in Warsaw, substantial progress has been made in the research and development of plasma and liquid-metal closed-cycle MHD systems. Both of these systems have relevance to the potential application of advanced, high-temperature nuclear power reactors as heat sources for MHD energy conversion. For fossil-fuelled open-cycle systems, engineering development has advanced to the prototype stage. Such were the conclusions made at the Fifth International MHD Conference, which was held in Munich from 19 to 23 April 1971 and attended by over 250 participants from 25 countries. At this conference, which brought together experts from all the major MHD development programs in the world, notably those in the USSR, USA, F.R. of Germany and Japan, 115 papers were presented.

A Critique of MHD Power Generation

Magnetohydrodynamic electrical power generation is a promising new technique for upgrading the efficiency of converting heat into electricity. The concept has been explored intensively but on a small scale during the past ten years, and the initial enthusiasm in it has been confirmed. Its utilization in base-load plants, in addition to increasing overall efficiency, can also lead to important reductions in the adverse environmental effects of thermal and air pollution. The projected efficiencies of large dual cycle systems are initially in the range of 47–50 percent, and improvements in technology could later increase this to 60 percent. In an MHD system, energy is extracted from a flowing electrically conducting fluid. The fluid may be either a seeded plasma or a liquid metal. Various MHD power cycles and systems are therefore under consideration. The status of these systems will be reviewed with emphasis on their application to large central-station commercial systems. The major technological problems and progress in the three major cycles (open cycle, closed-cycle plasma, and closed-cycle liquid metal) will be discussed in depth. In the open-cycle system, the engineering solutions that have been proposed for the major problems in the generator and auxiliary equipment will be detailed. In addition, the experience gained from the operation of a succession of generators will be summarized. In the case of the closed-cycle plasma system, the progress that has been made toward developing a generator with the requisite conversion efficiency will be cited. Recent cycle analyses that have established the conditions for matching these systems to current heat sources will also be reviewed and their implications noted. The potential of developing liquid-metal MHD systems for commercial application will be explored in the light of recently obtained experimental and analytical performance information. In particular, promising new techniques that can lead to improved efficiencies will be detailed.