Dynamic Solidification of Binary Aqueous Solution
| Project/Area Number |
14550174
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Kanazawa University |
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Principal Investigator |
KIMURA Shigeo Kanazawa University, Inst.of Nature and Environmental Technology, Professor, 自然計測応用研究センター, 教授 (70272953)
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| Co-Investigator(Kenkyū-buntansha) |
OKAJIMA Atsushi Kanazawa University, Graduate School of Natural Science, Professor, 自然科学研究科, 教授 (80013689)
KIWATA Takahiro Kanazawa University, Graduate School of Natural Science, Associate Professor, 自然科学研究科, 助教授 (40225107)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥4,000,000 (Direct Cost: ¥4,000,000)
Fiscal Year 2004: ¥800,000 (Direct Cost: ¥800,000)
Fiscal Year 2003: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2002: ¥1,800,000 (Direct Cost: ¥1,800,000)
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| Keywords | Phase Change / Solidification / Natural Convection / Convection Heat transfer / Mushy Layer / Double Diffusion / Numerical Analysis / Porous Medium / 連成熱伝達 / 対流熱伝達 / レイリー数 / ヌッセルト数 |
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| Research Abstract |
In this study solidification process of binary aqueous solution is investigated. Main goal of the present work is to develop a one-dimensional approximate model to predict the time-dependent behavior of the solid layer growth and decay. Since the solid layer formed in the aqueous solution becomes mushy (a porous layer), we first study the solidification in the water-saturated porous medium. Particularly the solid layer response when the cooling temperature varies with time is our major interest. One-dimensional model is developed in order to predict the temporal solid layer thickness. Experiments using a cubic container filled with water-saturated glass beads are carried out for testing the validity of the proposed one-dimensional model. Two-dimensional numerical analysis is also performed for the same purpose. It is found that the proposed one-dimensional model accurately predicts the both experimental and numerical results. Next we extend our one-dimensional model to solidification o
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f binary aqueous solution. Assuming the constant solid fraction in the mushy layer and the specified heat flux at the solid-fluid interface, which is effectively simulating the convective heat flux at the interface, the time-dependent heat conduction equation in the solid layer (mushy layer) and the thermal energy balance at the interface are combined to yield the transcendental equation for the unknown thickness of the mushy layer. Experiments are also carried out using the cubic container filled with aqueous sodium nitrate. Two different thermal boundary conditions are employed ; one is cooled from above, and the other is cooled from below. The former is characterized by the presence of vigorous convection in the liquid region, while the latter is dominated by diffusion. The solid-layer thickness and the solid fraction in the mush predicted by one-dimensional model again agree well with the experimental results, for the both thermal boundary conditions. It is found that the solid fraction in the mush formed by cooling from above has greater values than those by cooling from below. This is due to the different concentration of the interstitial solution in the mush. Since the mass diffusion is very small relative to thermal diffusion, the concentration in the interstice tends to accumulate when the system is cooled from below. We also investigate mixed convection heat transfer from a vertical cooled or heated cylinder. This has an important application for evaluating heat transfer rate of geothermal heat exchangers. Less
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Research Products
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