Performance Of MHD Generator Research Articles

Numerical Study on the Effect of Anode Position on the Performance of Disk MHD Generator

The unsteady-state quasi-one-dimensional numerical simulations of the disk MHD generator have been conducted for various anode position. The results indicate that the non-equilibrium ionization instability of the plasma can be effectively suppressed by the appropriate anode position, and thus, the performance of the non-equilibrium disk MHD generator can be improved. Moreover, when the geometry and boundary conditions of disk MHD generator are determined, the optimal position of the anode is predicted to maximize the enthalpy extraction rate of the generator.

Influence of Inlet Ionization Degree on Performance of Seed-free MHD Generator

Influence of Inlet Ionization Degree on Performance of Seed-free MHD Generator

Analyse the disk closed cycle MHD generator performance with the influence of channel characteristics

The enthalpy extraction ratio is one of the most significant parameter of a disk closed cycle MHD generator. There are two methods to improve the enthalpy extraction, those are the increase of channel cross-sectional area ratio and the implementation of inlet swirl. In this study, the mechanism of enthalpy extraction improvement has been confirmed by the two-dimensional numerical calculation. As a result, by increasing the channel cross-sectional area ratio of the disk MHD generator, the increase of static pressure and the velocity deceleration can be suppressed due to the Lorentz force, and it is possible to maintain a high flow velocity inside the channel and a high Hall parameter. The implemention of inlet swirl is possible to maintain a low static pressure inside the channel and the enthalpy extraction ratio rises due to the increase of Hall parameter. In addition, the channel cross-sectional area ratio increases due to the swirl implementation, the static pressure is kept low, and the channel inlet flow velocity increases. This also leads to the increase of enthalpy extraction ratio, that is the increase of output power.

Fundamental Studies On Development Of MHD (Magnetohydrodynamic) Generator Implement On Wave Energy Harvesting

As increasing of agricultural and industrial activities each year has led to an increasing in demand for energy. Possibility in the future, the country was not able to offer a lot of energy and power demand. This means that we need to focus on renewable energy to supply the demand for energy. Energy harvesting is among a method that can contribute on the renewable energy. MHD power generator is a new way to harvest the energy especially Ocean wave energy. An experimental investigation was conducted to explore performance of MHD generator. The effect of intensity of NaCl Solution (Sea Water), flow rate of NaCl solution, magnetic strength and magnet position to the current produce was analyzed. The result shows that each factor is give a significant effect to the current produce, because of that each factor need to consider on develop of MHD generator to harvest the wave energy as an alternative way to support the demand for energy.

Comparison of Generator Performance of Small-Scale MHD Generators with Different Electrode Dispositions and Load Connection Systems

AbstractThe performances of experimental and small scale DCW, DIW, HCW, HIW and Faraday MHD generators driven by a scramjet engine are compared by three-dimensional numerical simulation. Numerical results show that the maximum power output is obtained in the DCW generator. The electrodes on the side walls in the DCW and the HCW generator suppress the loss of electrode voltage drop compared with the DIW and the HIW generator. Since the volume-averaged Hall parameter of plasma is less than unity for all the generators, the HCW and the HIW generator have less electric power output than other generators. The power output extracted by the Faraday generator is comparable to that extracted by the DCW generator. The Faraday generator, however, requires the load and the inverter to each number of electrode pairs, so that the complication of external circuits and the increase in cost may be apprehended. The authors conclude that the DCW generator is suitable for the experiment of scramjet engine driven MHD generators.

Influence of Asymmetric Placement of Radio-Frequency Induction Coil on Performance of Nonequilibrium MHD Generator

Influence of Asymmetric Placement of Radio-Frequency Induction Coil on Performance of Nonequilibrium MHD Generator

Numerical Study of an AC MHD Generation with Double-side Exciting Winding

This paper studies physical phenomena, performance and optimal operating point of an AC MHD generator under the slip value by using a numerical simulation. The double-side exciting winding of the generator is considered. Its structure consists of a channel, an insulator and stators. Channel type is a flat rectangular and the liquid flows along the channel as a conductor. Channel wall acted as an insulator separates metal fluid and stator coils. The top and bottom stator winding of the generator is connected to polyphase system. Under this condition, it can produce a magnetic field by means of time harmonic function in the same direction of the metal fluid. An interaction between traveling wave and metal fluid is explained by finite element method under Maxwell's equation and Ohm law. The distribution of magnetic vector potential and magnetic flux density throughout channel is evidently shown in xy-plane. Power flow in AC MHD generator is evaluated by slip value. The optimal operating point of an AC MHD generator performance is reported by active power 0.99kW, reactive power 50kVAR, mechanical power 1.58kW, power dissipation 0.59kW and electrical efficiency 62.5%.

Characterization of the three-dimensional supersonic flow for the MHD generator

A numerical procedure based on a five-wave MHD model associated with non-ideal, low magnetic Reynolds number MHD flows was developed in the present study for analyzing the flow fields in the MHD generator of a MHD bypass scramjet. The numerical procedure is composed of an entropy conditioned scheme for solving the non-homogeneous Navier-Stokes equations, in conjunction with an SOR method for solving the elliptic equation governing the electrical potential. It was found that a separation would take place near the downstream edge of the second electrode, where the local adverse pressure gradient is large, and the core of the flow field is characterized as a 2-D flow due to the Hartmann effects along the direction of the magnetic field. The electric current lines would be increasingly distorted as the magnetic interactive parameter increases, and even induce an eddy current. Induced eddy current was also found in the different cross-sections along the axial direction, all of these would definitely deteriorate the performance of the MHD generator. The cross-sectional M-shape velocity profile found along the axial direction between the insulating walls is responsible for the formation of the vortex flow at the corner of the insulator cross-section, which, in turn, induces the corner eddy current at the corner. A numerical parametric study was also performed, and the computed performance parameters for the MHD generator suggest that, in order to enhance the performance of MHD generator, the magnetic interaction parameter should be elevated.

Two-dimensional numerical simulation on performance of liquid metal MHD generator

The performance of a liquid metal MHD generator is investigated with a two-dimensional numerical simulation. The effects of the electrode length, the position of current lead connection, and the insertion of an insulator on the performance are examined taking account of the current flow in the electrode. There exists an optimal electrode length for a given distribution of applied magnetic flux density. For a short electrode, the efficiency decreases because the power output becomes small. For a long electrode, on the other hand, the efficiency also decreases owing to the leakage current from the upstream and downstream edges of the electrode. An optimal current lead position was revealed. This fact is ascribed to the distributions of induced magnetic field and the current flow in the electrode. It was found that insertion of the insulator is effective for improving the performance, by which the eddy current can be reduced. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(1): 25–32, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ eej.20165

MHD Flow Behavior and Performance of Middle Scale Nonequilibrium Subsonic Disk MHD Generator

MHD flow behavior and the performance of a middle scale nonequilibrium subsonic disk MHD generator have been examined with time-dependent r-z two- and r-θ-z three-dimensional numerical simulations. The generator performance, such as the enthalpy extraction ratio and the isentropic efficiency, can be varied time-dependently because the boundary layer separation occurs and the fluid flow fluctuates in the diffuser. However a mean enthalpy extraction ratio of 23% and a mean isentropic efficiency of 83% are achieved for the optimal load resistance under the inlet stagnation pressure of 0.75atm. This performance is almost high enough for the commercial generator. When the low electron temperature plasma flows into the generator channel, the ionization instability occurs and the discharge structure becomes nonumiform in θ-direction, which deteriorates the generator performance considerably. This fact indicates the importance to produce the proper plasma for the power generation by optimizing the generator channel or utilizing the preionization.

Improvement of performance of disk MHD generator with argon by introduction of swirl

AbstractAn experimental study of performance of the disk MHD generator with argon was carried out using a shock‐tube driven facility. An inlet swirl was introduced in the MHD channel in order to improve the enthalpy extraction and the isentropic efficiency. The experimental results were compared with those of the disk MHD generator without the inlet swirl. A high enthalpy extraction of 25.7% was obtained and the highest isentropic efficiency for argon was achieved at the same time in the present experiment. The measured static pressure in the MHD channel was kept lower than that without the inlet swirl. This has suggested that the introduction of the inlet swirl reduces the retarding force for the flow and that the increase of the enthalpy extraction is ascribed to the increase of the flow velocity and of the electrical efficiency. Furthermore, the flow without shock wave was observed at low seed fractions and low load resistances. At the same time, it was found for the first time that when there was no shock wave, the isentropic efficiency became higher than that with the shock wave. © 2002 Wiley Periodicals, Inc. Electr Eng Jpn, 141(1): 18–25, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.10045

Performance of disk MHD generator with high magnetic flux density

Performance of disk MHD generator with high magnetic flux density

非平衡MHD発電プラズマの状態と発電性能に関する解析的検討

非平衡MHD発電プラズマの状態と発電性能に関する解析的検討

The effect of nozzle load resistance and stagnation gas pressure on the performance of a disk MHD generator with small area ratio

The effect of nozzle load resistance and stagnation gas pressure on the performance of a disk MHD generator with small area ratio

Performance of disk MHD generator with high magnetic flux density

The advantages of implementing high magnetic flux density up to 10 T for a commercial size closed cycle disk MHD generator with supersonic flow are discussed, and the technical feasibility of its superconducting magnet is studied. The present study suggests a high performance of the generator with high magnetic flux density. A possible construction of the magnet, in which a special structure is arranged to sustain a large electromagnetic force induced between the coils, is shown.

MHD Flow Behavior and Performance of Subsonic Non-equilibrium Disk MHD Generator Driven by Shock-tube Facility.

MHD flow behavior and the performance of an experimental nonequilibrium subsonic disk MHD generator driven by a shock-tube facility have been examined with time-dependent γ-z two-dimensional and γ-θ-z three-dimensional numerical simulations. In the subsonic MHD generator with two throats, the choking position is found to depend on the strength of MHD interaction. For optimal or high load operations, the flow chokes at the downstream throat and the subsonic flow is maintained in the generator channel. For low load operations, on the other hand, the flow chokes at the upstream throat and the flow becomes supersonic. In the generator under the subsonic flow condition, the relation between enthalpy extraction ratio and isentropic efficiency can be described as a function of Mach number at the anode for a fixed Mach number at the cathode. When the magnetic flux density is low, the inlet stagnation pressure should be decreased to achieve high enthaply extraction ratio and isentropic efficiency. The proper fluid flow and discharge structure can be realized under the optimal load resistance. Under the low resistance, however, shock-waves and ionization instability can occur and the generator performance can be deteriolated.

ディスク形MHD発電機の性能に与える高周波電磁界印加の効果

ディスク形MHD発電機の性能に与える高周波電磁界印加の効果

片側アノード電極ディスク形MHD発電機の性能

片側アノード電極ディスク形MHD発電機の性能

Effects of diffuser shape and back pressure on the performance of disk MHD generators

The effects of diffuser shape and back pressure on the performance of closed-cycle disk MHD generators are investigated with two-dimensional numerical simulations taking account of the boundary layer. The enthalpy extraction ratio decreases and fluctuates periodically with increase in the back pressure. The amplitude of power output fluctuation and the period depend on the volume of the inverse flow region. For the reduced height diffuser, the inverse flow region is suppressed and the fluctuation becomes smaller than that for the constant height diffuser. When operated with a back pressure lower than an optimum value, the diffuser does not work because of reacceleration in the diffuser. For the higher back pressure, on the contrary, the inverse flow region propagates into the MHD channel, then the enthalpy extraction ratio is reduced and the Mach number at the exit of the MHD channel becomes lower than unity. For the optimum back pressure, high enthalpy extraction ratio is achieved and the adiabatic efficiency at the diffuser exit is decreased by several percent from that evaluated at the MHD channel exit. © 2000 Scripta Technica, Electr Eng Jpn, 133(2): 11–19, 2000

ブローダウン方式MHD発電機壁面のシード付着軽減による発電性能の改善

ブローダウン方式MHD発電機壁面のシード付着軽減による発電性能の改善