著者

新井 崇洋 古谷 正裕

出版者

社団法人 日本伝熱学会

雑誌

日本伝熱学会論文集 (ISSN:09189963)

巻号頁・発行日

vol.15, no.3, pp.91-100, 2007 (Released:2008-02-25)

参考文献数

10

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We proposed ultra rapid solidification and atomization technique, CANOPUS (Cooling and Atomizing based on NOble Process Utilizing Steam explosion), using small-scale vapor explosions to make an amorphous metal. The CANOPUS method is suitable for rapid cooling and atomization process, which utilizing sustainable small-scale vapor explosions. In order to apply the CANOPUS method to a high melting point metal, it is necessary to make a small-scale vapor explosion occur at a high temperature of the molten metal. Small-scale experiment is conducted to develop the vapor explosion promotor in which spontaneous vapor explosion can occur at a high temperature of a molten metal. Spontaneous vapor explosion do not occur when water at 80°C is used as a coolant. However, spontaneous vapor explosion occurs when water at 80°C with salt additives is used as a coolant. Specifically, lithium chloride solution generates spontaneous vapor explosions at the highest temperature of the molten tin in the experiment. In order to clarify the triggering mechanism of the spontaneous vapor explosion when the promotor is used as a coolant, a high-temperature solid stainless steel sphere is immersed into a coolant. The interfacial temperature of the stainless steel sphere is measured, and the behavior of a vapor film around the stainless steel sphere is observed with a digital video camera. As a result, salt additives resulted in an increase of quench temperature in all salt solutions. The quenching curves of each coolant indicate that the salt additives improve the film boiling heat transfer. The improvement of the film boiling heat transfer causes an unstable formation of the vapor film and a rise of the quench temperature. It is clarified that the salt additives to water promotes a vapor film collapse. Comparing two experiments, the quench temperature of each solution is in close agreement with the upper limit of the molten tin temperature that causes spontaneous vapor explosion. This result suggests that the vapor film collapse triggers spontaneous vapor explosion.

著者

福田 哲士 増田 幸男 福江 高志 畠山 友行 石塚 勝 小泉 雄大

出版者

社団法人 日本伝熱学会

雑誌

日本伝熱学会論文集 (ISSN:09189963)

巻号頁・発行日

vol.30, no.1, pp.1-12, 2022 (Released:2022-02-22)

参考文献数

21

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This study describes the 40 mm scale small axial fan P - Q curves mounted in high-density packaging electronic equipment. An accurate prediction of supply flow rate by fans strongly affects the reliability of the cooling design. However, in high-density packaging electronic equipment, the fan performance is affected by the mounting components around the fans, and the accurate prediction of the supply flow rate becomes difficult. In this paper, by a CFD analysis, visualization around the fan impellers with the obstructions was conducted. By comparing the predicted result of the P- Q curves by the proposed analytical method and experiment, the proposed analysis's effectiveness was evaluated.

著者

福江 高志 義基 貴史 石塚 勝 中川 慎二

出版者

社団法人 日本伝熱学会

雑誌

日本伝熱学会論文集 (ISSN:09189963)

巻号頁・発行日

vol.16, no.4, pp.147-156, 2008 (Released:2009-04-23)

参考文献数

14

被引用文献数

2

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This paper describes the effects of frame and inlet sizes of an electronic casing on the cooling fan performance. The performance of air-cooling fans is defined by their P-Q characteristics. Recent studies report that P-Q curves of cooling fans depend considerably on their operational environments. It is impossible for accurate CFD (Computational Fluid Dynamics) analyses to be performed on the thermal design of electronic equipments, including fans. In this study, we measured a fan performance in some frames and explored effects of environment for their P-Q characteristics, especially effects from area of frame and cooling air inlet sizes. From experimental results, it was found that the fan P-Q characteristics, especially flow rate were affected strongly by inlet sizes.

著者

村上 陽一

出版者

社団法人 日本伝熱学会

雑誌

日本伝熱学会論文集 (ISSN:09189963)

巻号頁・発行日

vol.20, no.2, pp.15-26, 2012 (Released:2012-08-10)

参考文献数

46

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Photon upconversion based on triplet-triplet annihilation (TTA) of excited triplet molecules is drawing attention due to its applicability for weak incident light, possessing a potential for improving efficiencies of solar energy conversion devices. Since energy transfer between triplet levels of different molecules and TTA are based on the Dexter mechanism, inter-molecular collision is necessary and hence the majority of previous studies have been done with organic solvents, which are volatile and flammable. This paper presents the development and characterization of phase-stable photon upconverters fabricated with ionic liquids, which are room temperature molten salts with negligible vapor pressure and high thermal stability. The employed aromatic molecules, which are carrier of photo-created energies and are non-polar (or weakly polar) molecules, are found to be stable in the polar environment of ionic liquids, contrary to expectation. The mechanism of the stable solvation is proposed. The upconversion quantum yields are found to rapidly saturate as the excitation light power increases. An analytical model was developed and compared with the experimental data. It is shown that ionic liquids are not viscous media for the purpose of TTA-based upconversion.

著者

松本 充弘 中澤 伸之

出版者

社団法人 日本伝熱学会

雑誌

日本伝熱学会論文集 (ISSN:09189963)

巻号頁・発行日

vol.15, no.2, pp.55-61, 2007 (Released:2008-01-01)

参考文献数

7

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Impingement process of a small droplet on solid wall was investigated with molecular dynamics simulation technique. A liquid droplet consisting of about 14,000 Lennard-Jones particles was thrown with a given speed onto a smooth wall, and the change of its size and shape was analyzed. After the collision, the droplet spreads on a “hydrophilic,” or strongly interacting, wall, but bounces on a “hydrophobic” wall. The spreading behavior is suppressed by surrounding gas.