著者

奥野 喜裕 村上 朝之

出版者

東京工業大学

雑誌

基盤研究(B)

巻号頁・発行日

2007

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本研究では、クローズドサイクルMHD発電の実用化に向けて、「MHD発電機の実用高度化」研究を戦略的に推進した。衝撃波管駆動MHD発電実験装置、および高精度電磁流体数値シミュレーションを駆使して、類似の発電システムの中では世界最高の発電出力密度を達成するとともに、発電機形状の改良による発電性能の向上を実証し、理論的裏付けとともに,更なる性能向上に向けての確度の高いロードマップを提示することができた。

著者

野田 英樹 奥野 喜裕 伊坪 徳宏

出版者

日本LCA学会

雑誌

日本LCA学会誌 (ISSN:18802761)

巻号頁・発行日

vol.11, no.2, pp.172-188, 2015 (Released:2015-11-09)

参考文献数

25

被引用文献数

1 1

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Objective. Photovoltaic (PV) power systems are considered an essential component of environmental friendly society. However, the land area required for generating unit amount of power by PV system is larger than that for an equivalent coal-fired power system. In Japan there has been some instances of PV power systems being installed in forest areas. Therefore, the purpose of this study is to explore the impact of PV power systems on Japanese forests. Forest vegetation is classified into the 13 types used in the “Life cycle Impact assessment Method based on Endpoint modeling 2 (LIME2)” methodology. This will allow us to establish the relationship between the reduced CO2 emissions of a PV power system and the system’s impact on forest by way of land use, compared with those of coal-fired power system.Results and Discussion. The environmental impact of a PV power system installed on a roof was calculated as 6.3% of the impact of a coal-fired power system. In contrast, placing the PV power system in oak or pine forest had a substantially greater environmental impacts, of 76.7% and 99.9% respectively. Following sensitivity analysis, it became apparent that the area required by a PV power system per generated unit of power is the most important factor. For example, with regard to the oak forest, the environmental impact of the PV power system can be reduced from 99.9% to 74.2% by decreasing the area required per generated unit of power from 15,200m2/MW to 11,000m2/MW. A further improvement of 5.8% can be achieved by planting grass under PV panels.Conclusions. LIME2 damage factors were used to classify land use impact for 13 vegetational types of Japanese forest. From the calculated results, it is clear that the environmental impact of PV power system land use on a forest should not be disregarded; however, the level of that impact will depend on the vegetational classification. Furthermore, reducing the utilization rate of the PV power system is an effective way to lessen the impact of land use.

著者

鶴岡 美緒 田中 学 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.138, no.3, pp.236-241, 2018-03-01 (Released:2018-03-01)

参考文献数

28

被引用文献数

1 1

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Power generating characteristics of seed-free linear shaped Faraday type and disk shaped Hall type MHD generators are examined by two-dimensional numerical simulation with changing the inlet ionization degree. A liner shaped Faraday type generator can get stable and high power output at high inlet ionization degree. The net enthalpy extraction ratio, however, is reduced owing to the increase in the required preionization power. At low inlet ionization degree, on the other hand, ionization instability occurs and the enthalpy extraction ratio decreases. A disk shaped Hall type generator can get high net enthalpy extraction ratio even at low inlet ionization degree under a low preionization power. The net enthalpy extraction ratio decreases for an excessive inlet ionization degree because of a strong MHD interaction.

著者

卓 新民 田中 学 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.136, no.10, pp.779-784, 2016-10-01 (Released:2016-10-01)

参考文献数

17

被引用文献数

2 2

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The performance and plasma stability in a high-temperature inert gas plasma MHD generator with a high enthalpy extraction ratio have been simulated numerically. To achieve a high enthalpy extraction ratio, various generator channel lengths and magnetic flux density distributions are examined so as to improve the MHD interaction strength and effective electrical conductivity. It is found that an enthalpy extraction ratio of 30% is reachable for high-temperature inert gas plasma MHD generator, and as being similar to an experimental small-scale generator, steady and homogeneous plasma can be realized at a high inlet total temperature even for a high enthalpy extraction generator with long channel length and shaped magnetic flux density distribution.

著者

田中 学 泉 裕一朗 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.136, no.2, pp.205-210, 2016-02-01 (Released:2016-02-01)

参考文献数

22

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MHD (magnetohydrodynamic) electrical power generation experiments have been conducted with a seed-free high temperature inert gas plasma in a disk-shaped Hall-type generator driven by a single-pulsed shock tunnel. Xenon is used as a working gas to archive a high performance at a low inlet total temperature, where the total gas temperature is varied in the range of 4600-10000K at the generator inlet. An enthalpy extraction ratio of 4.8% is obtained at the inlet total temperature of 7000K, and this value is much higher than that for argon at the same inlet total temperature. The unstable and non-uniform plasma attributed to ionization instability is observed at a high magnetic flux density and a high load resistance.

著者

田中 学 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.135, no.8, pp.527-532, 2015-08-01 (Released:2015-08-01)

参考文献数

22

被引用文献数

5 3

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R-θ two dimensional numerical simulations have been carried out to clarify the plasma behavior in a high-temperature inert gas plasma disk-shaped MHD generator. At low inlet total temperature and high load resistance, the plasma has spiral structure which is similar to the non-uniform structure under the weak noble gas ionization condition in a seed-plasma MHD generator. As seen in a linear-shaped faraday-type MHD generator, the plasma becomes stable with increase in the inlet total temperature because the coulomb collision of electrons becomes dominant. Even at low inlet total temperature, the ionization instability can be suppressed for low load resistance, because the relatively low electron temperature due to less Joule heating makes the ionization relaxation time longer than plasma residential time.

著者

小松 文彦 田中 学 村上 朝之 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.134, no.7, pp.620-625, 2014 (Released:2014-07-01)

参考文献数

9

被引用文献数

5 5

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High temperature inert gas (argon) plasma MHD electrical power generation using a linear shaped channel with Hall and diagonal connections has been conducted. It is revealed from the observation by using a high-speed camera that the MHD power-generating plasma is almost stable regardless of the connection type. Enthalpy extraction ratios of 5.6% for the Hall connection, 6.7% for the diagonal connection (diagonal angle 53∼66 degree), and 10.1% for the diagonal connection (diagonal angle 36∼48 degree) have been achieved under the operating conditions of an inlet total temperature of 9000K, an inlet total pressure of 0.105MPa, and a magnetic flux density of 4.0T. The output power can suffer from a low electric field in the upstream region in a Hall connection, and is improved for no Hall current condition in a diagonal connection.

著者

田中 学 村上 朝之 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.134, no.7, pp.614-619, 2014 (Released:2014-07-01)

参考文献数

13

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MHD power generation experiments have been conducted by using a single-pulsed shock-tunnel facility, where the high temperature inert gas (pure argon) at a fixed total temperature of 9000K is introduced into a linear shaped Faraday type generator without any seeding. The fluctuations in the output power and the light emission from the plasma are found to be small, and the pure inert gas plasma seems to be rather stable free from the ionization instability. The output power is improved with increasing the magnetic flux density in almost quadric way and the enthalpy extraction ratio does not depend on the inlet total pressure (11.2%-12.9% for 0.063MPa-0.105MPa). The generator performance obtained here is surely competitive or superior to that of conventional seed plasma MHD generators in the past.

著者

田中 学 村上 朝之 奥野 喜裕

出版者

一般社団法人 電気学会

雑誌

電気学会論文誌B(電力・エネルギー部門誌) (ISSN:03854213)

巻号頁・発行日

vol.134, no.5, pp.464-469, 2014 (Released:2014-05-01)

参考文献数

16

被引用文献数

3 3

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The plasma fluid flow behavior and power generation characteristics in a Faraday-type magnetohydrodynamics (MHD) generator using high temperature inert gas (argon) plasma has been examined by a time-dependent two-dimensional numerical simulation. The inhomogeneous and unstable plasma at an inlet total temperature of 7000K results in the reduction and fluctuation of the output power. The plasma changes to homogeneous and stable one with the increase in the inlet total temperature to 9000K. One of the reasons of the suppression of the ionization instability can be due to the weakness of the dependency of the electrical conductivity on the electron number density because the coulomb collision of electrons becomes dominant under the departure from Saha equilibrium.