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| 1.
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Amagai, Kenji ; Hashimoto, Hiroyuki
概要:
application/pdf<br />Journal Article<br />Constitutive equations regarding the drift flux model for a multiphase flow consisting of molten material and its solidified particles were thermodynamically derived under a condition of local
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quasiequilibrium. The basic equations, including the conservation equations and the constitutive equations for the multiphase flow, were expressed in dimensionless forms. The theory developed here confirmed that the temperature fields closely depended on the Lagrangian derivative of the solid fraction accompanying the latent heat effect, and was characterized by the Stefan number. It was also suggested that the simplified basic equations corresponding to the phase equilibrium diagram were useful in the analysis of multiphase flow with solid-liquid phase change.
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| 2.
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Hashimoto, Hiroyuki ; Amagai, Kenji
概要:
application/pdf<br />Journal Article<br />The conservation equations of mass, momentum and energy for a molten liquid flow of two chemical constituents with their solidified particles were derived by means of the averaging method. The
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drift flux model equations for the fine particles were also derived under a locally homogeneous approximation. The present model suggests that the energy equation should have energy transport terms corresponding to the heat conduction, the migration of particles and the diffusion of chemical constituents. As representative examples, these energy transports were evaluated quantitatively for binary molten salt and liquid alloy under the assumption of a locally thermal equilibrium. The results show that the energy conservation equation for solidified particles and melt flow should include an energy transport term due to particle migration.
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| 3.
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稲田, 茂昭 ; 西田, 浩二 ; 鳥羽, 正幸 ; 内田, 憲之
概要:
application/pdf<br />Journal Article<br />The heat transfar of a drop impinging on a heated surface is influenced consid
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erably by liquid-solid contact and the accompanying formation of a vapor film. The aim of this study was to grasp the liquid-solid contact state more quantitatively by informations based on the temperature fluctuation of the heated surface during the impingement and the behavior of the drop on the heated surface. Experiments were conducted using two different drop diameters (2.3 and 4.0 mm), drop subcooling of 88 K, impinging Weber numbers of 12-98, and an initial temperature for the heated surface of 160-420℃. The unique miniaturization behavior of the drop was illustrated schematically by the imageprocessing method. The existence of four drop-boiling heat-transfer modes which clearly could be classified according to the initial temperatureof the heated surface was proved.
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| 4.
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稲田, 茂昭 ; 宮阪, 芳喜 ; 佐久本, 政和 ; 茂木, 郁男
概要:
application/pdf<br />Journal Article<br />The present report aims at presenting basic data to prove the wetability of a
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heated surface contaminated by scale adherence by comparing the behaviors of a water droplet on a contaminated surface and a glossy surface polished by emery paper. A water droplet (2.3 mm in dia. ) of about 18℃ is dropped from a height of 20 mm above the heated surface and the evaporation behavior on the heated surface is photographed by a high speed camera. The initial temperatures of the heated surface are in the range of 140-220℃. At temperatures of the heated surface above 200℃, in the case of a fresh surface, the residence time of a drop on the heated surface is about 13 ms. While in the case of a contaminated surface, even if the drop is about to rebound from the heated surface, its root is so firmly contacted with the heated surface through the thin liquid film that the residence time is longer than that of the fresh surface. This fact proves that the surface with scale has a high wetability.
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| 5.
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INADA, Shigeaki ; MIYASAKA, Yoshiki ; SAKUMOTO, Masakazu
概要:
application/pdf<br />Journal Article<br />This report describes liquid-solid contact behavior in the subcooled pool transition-type boiling regime and the minute bubble emission boiling regime, detected by a void probe that uses a
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series-resonance circuit. This probe can approach the heated surface within two to three micrometers. The liquid-solid contact state discussed in this report means the nucleate boiling state caused by liquid invasion or Leidenfrost state caused by liquid rush onto the dry part on the heated surface. The dried area on the heated surface was estimated on the basis of the void signal, and the relation between the dried area on the heated surface and the measured heat flux was clarified by introducing a nucleate boiling model.
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| 6.
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INADA, Shigeaki ; MIYASAKA, Yoshiki ; SAKAMOTO, Kenji
概要:
application/pdf<br />Journal Article<br />The heat flux was measured at the second burnout point of pool boiling over the range of high subcooling of 30 K to 88 K, under atmospheric pressure. The relation between the heat flux and
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subcooling was obtained by a mathematical model based on the mass-transfer mechanism of evaporation and condensation through a coalescent vapor bubble, and by a kinetic theory of molecules. The relationship equation gave fairly good agreement with the experimental results and showed that the second burnout heat flux did not increase unlimitedly with subcooling, but that it had a maximum value at a certain subcooling.
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| 7.
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稲田, 茂昭 ; 宮阪, 芳喜 ; 泉, 亮太郎
概要:
application/pdf<br />Journal Article<br />Experiments on pool transition boiling of water under atmospheric pressure on a heated surface 10mm in diameter were conducted for subcooling 15-50K. The mass flux of condensation of a detached
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coalescent vapor bubble was experimentally estimated by a mathematical model based on the mass transfer mechanism of condensation. As a result, it is clarified that the mass flux of condensation of the detached bubble was influenced by the initial growing velocity of a vapor bubble immediately following the detached bubble. The disappearance velocity of the detached bubble defined as a ratio of the bubble diameter at the departure to the time required until the disappearance, is in the range 0.2 to 2.0m/sec. The disappearance velocity is proportional to the initial growing velocity of the bubble, to the square of the heat flux of the heated surface and to the cube of the wall superheat, separately.
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| 8.
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稲田, 茂昭 ; 宮阪, 芳喜 ; 西田, 浩二
概要:
application/pdf<br />Journal Article<br />This paper deals with transient heat transfer for a water drop impinging on a heated surface in the surface temperature range from maximum boiling rate point to the non-wetting region. The
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boiling curves were obtained by analyzing the transient temperature variation inside the heated surface taking account of the time variation of the area covered by the drop. By comparing the boiling curves obtained in this way with that for pool boiling, the heat flux in both cases increases with increasing subcooling, while the maximum heat flux point of the boiling curve was located on an extension of the nucleate pool boiling curve and that the boiling heat transfer for a drop on the heated surface was classified into four types according to the degree of subcooling and to the heated surface temperature.
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| 9.
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稲田, 茂昭 ; 宮阪, 芳喜 ; 泉, 亮太郎 ; 小林, 盛一
概要:
application/pdf<br />Journal Article<br />本報は伝熱面直径10mm, サブクール度15～50Kの範囲で水のプール沸騰実験をおこない, 遷移沸騰的領域の伝熱機構を蒸発と凝縮が同時におこる質量輸送機構に
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もとづいて考察したものである. この領域の沸騰特性に対して影響をおよぼす重要な因子である凝縮質量流束と伝熱面の乾燥部面積の時間変化を見積り, さらに伝熱面局所の温度変動との対応からサブクール遷移沸騰の液侵入機構に対する一つの解釈を与えることを試みた.
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