Effects of Area Ratio on Performances of Dish MHD Generator with Argon

Yamasaki

2006

Self Cite

SUMMARYThe present experiment has aimed at the improvement in the performance of a shock-tube-driven disk CCMHD generator. For that purpose, an experimental setup was arranged as follows: (1) An inlet swirl was introduced.(2) The area ratio of the disk generator was small. (3) A cesium-seeded helium gas was used as a working medium. Not only these factors but also the production of a homogeneous plasma contributed to outstanding performance characterized by an isentropic efficiency of 63% and an enthalpy extraction ratio of 30.8% at a stagnation temperature of 2250 K and stagnation pressure of 0.14 MPa. Furthermore, a maximum electrical power output of 1.23 MW and a maximum power density of 297 MW/m 3 were obtained.

Section: Progress Of Experimental Research At Tokyo Institute Of Techmentioning

confidence: 99%

Experiments of the improvement in the performance of a disk CCMHD generator

Murakami

Yamasaki

2006

Self Cite

“…The disk itself in the Disk-PIA is made of acrylic, and the circuit path has the same shape as the Disk-RLN2 [7], which has been quite successful thus far. The Disk-PIA has three copper induction coils with different central diameters (diameters: 95.5, 119.5, 132.5 mm) for use in supplying high-frequency power embedded in the opposing disk.…”

Section: Structure Of the Disk-pia In The Disk Mhd Generatormentioning

confidence: 99%

The effect of an externally applied radio‐frequency electromagnetic field on the performance of a disk MHD generator

Fujino

Watanabe

et al. 2002

Self Cite

SUMMARYThe effects of an externally applied radio-frequency (rf) electromagnetic field on the nonequilibrium performance of a disk MHD generator were examined experimentally. As a preliminary experiment, plasma production by the applied rf electromagnetic field was attempted in the disk generator (Disk-PIA), in which rf induction coils were embedded in the one-side disk wall, under the conditions of no seeding, no flow, and no magnetic field. From the results of the preliminary experiment, it was confirmed that the argon plasma (~110 Torr) was produced uniformly in the azimuthal direction by the rf electromagnetic field even in the presence of exposed anodes in the faced disk wall and metallic support at the disk center. In MHD power generation experiments with the Disk-PIA installed in the shocktube facility, the increase in the electrical output and more indiscrete discharge attributed to the rf electromagnetic field were verified with good reproducibility for the first time.

“…Previous work has suggested that a disk MHD generator with a small cross-sectional area ratio (outlet cross section/inlet cross section of the MHD generator) makes it possible to obtain the high isentropic efficiency [1]. It has been stated that the relationship between the enthalpy extraction ratio and isentropic efficiency depends on the cross-sectional area ratio and the Mach number at the exit of the generator.…”

Section: Introductionmentioning

confidence: 99%

“…Since the electron energy gain by Joule heating [Eq. (1)] and the energy loss by collisions [Eq. (2)] are in balance, electron energy equation (1) or (2) can be solved analytically for the electron temperature.…”

Section: Introductionmentioning

confidence: 99%

“…It is well known that ionization instability results in nonuniformity of the plasma, thus degrading power generation performance. Although fluid-dynamical investigation of the performance has been conducted, the effect of the behavior of the nonequilibrium MHD seed plasma has never been considered in previous investigations [1,2]. The present study is based on a simple analytical calculation rather than a numerical simulation, solving differential equations to improve the analytical study.…”

mentioning

confidence: 99%

See 1 more Smart Citation

An analytical study of the plasma conditions and performance of an MHD generator

Murakami

Nakata

et al. 2003

Self Cite

SUMMARYIn order to investigate the effects of plasma conditions on fluid-dynamical prediction of the performance of an MHD generator, local steady-state calculations are employed. The effective Hall parameter and effective electrical conductivity are estimated by taking the linear theory of ionization instability into account. The results of analytical calculations are compared with experimental ones. Although a fully ionized seed condition, which suppresses instability, provides the highest power generation performance, the condition could be realized only at a high seed fraction in the experiments. It is suggested by the analysis that the fully ionized seed plasma produced at a low seed fraction is desirable in order to achieve high performance. The analysis implies that instability due to insufficient or excessive electron temperatures is a performance-limiting factor. The effects of plasma conditions on performance are clearly explained by the present simple analysis. Key words: MHD generator; ionization instability; fully ionized seed condition; generator performance. IntroductionIn recent researches on nonequilibrium closed-cycle MHD generation, most attention has been paid to the improvement of isentropic efficiency, where h I and h f denote the initial and final total enthalpy, respectively), as well as the enthalpy extraction ratio (= electrical output power/thermal input). Previous work has suggested that a disk MHD generator with a small cross-sectional area ratio (outlet cross section/inlet cross section of the MHD generator) makes it possible to obtain the high isentropic efficiency [1]. It has been stated that the relationship between the enthalpy extraction ratio and isentropic efficiency depends on the cross-sectional area ratio and the Mach number at the exit of the generator. The effects of stagnation pressure on the performance have also been examined in order to elucidate the fluid-dynamical features of the disk MHD generator [2].In the present work, local steady-state analytical calculations are conducted to investigate the effect of plasma conditions on the performance of the MHD generator, taking the linear theory of ionization instability into account. It is well known that ionization instability results in nonuniformity of the plasma, thus degrading power generation performance. Although fluid-dynamical investigation of the performance has been conducted, the effect of the behavior of the nonequilibrium MHD seed plasma has never been considered in previous investigations [1,2]. The present study is based on a simple analytical calculation rather than a numerical simulation, solving differential equations to improve the analytical study. The results of the analytical calculation are compared with experimental results. Procedure of Analysis Exchange of electron energyCesium-seeded argon gas is used as a working medium for the MHD generator. The nonequilibrium seeded plasma consists of argon atoms, argon ions, cesium atoms, cesium ions, and electrons. In the present analysis, a twotemperatur...