| Project/Area Number |
09555072
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 展開研究 |
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| Research Field |
Thermal engineering
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| Research Institution | Yokohama National University |
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Principal Investigator |
IIDA Yoshihiro Yokohama National Univ., Fuculty of Engng., Professor, 工学部, 教授 (90005299)
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| Co-Investigator(Kenkyū-buntansha) |
TSUYUKI Toshikatsu Tokyo Womens Med. College, School of Nursing, Ass. Professor, 看護短大, 助教授 (90155440)
TAKASHIMA Takeo Yokohama National Univ., Fuculty of Engng., Research Ass., 工学部, 助手 (40197091)
OKUYAMA Kunito Yokohama National Univ., Graduate School of Engng., Ass. Professor, 工学研究科, 助教授 (60204153)
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| Project Period (FY) |
1997 – 1998
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| Project Status |
Completed (Fiscal Year 1998)
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| Budget Amount *help |
¥5,500,000 (Direct Cost: ¥5,500,000)
Fiscal Year 1998: ¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 1997: ¥3,800,000 (Direct Cost: ¥3,800,000)
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| Keywords | Boiling Heat Transfer / Heat Transfer Augmentation / Free Particles Bed / Enhancement of Heat Transfer / Passive Method / Augmentation Mechanism / Nucleate Boiling / Fouling |
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| Research Abstract |
A passive technique to augment boiling heat transfer characteristics by freely movable solid particles preset around the heating surface is proposed and studied experimentally. The particles are fluidized by vapor bubbles generated on the surface and act to augment heat transfer. Further, they act to remove the fouling layer which may be formed on the surface.
A cylindrical heater of 0.88mm in diameter is set in a bed whose particles are freely movable in test liquid and nucleate boiling heat transfer characteristics are measured. Materials used for particles are cubic alumina, glass and porous alumina and the diameter ranges from 0.3mm to 2.5mm. Liquids tested are water and ethanol. Augmentation ratio of heat transfer becomes large with the increase of heat flux and reaches the maximum at a medium heat flux condition. The maximum augmentation ratio obtained was about 10 times of those in liquid. The maximum heat flux is also measured versus the depth of heater under the surface of particles bed.
Another series of experiments is made for boiling heat transfer on a flat heating surface. Metal particles such as aluminium are examined as well as alumina and glass particles. Effect of particles geometry is also examined. Much effect is obtained in experiments with a finite cylindrical particles.
The Maximum augmentation ratio obtained in this case reaches about 7 times of those in liquid. Cleaning effect of the fouling layer on the heating surface is recognized in experiments using NaCl solution.
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