| Project/Area Number |
59420024
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| Research Category |
Grant-in-Aid for General Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Research Field |
Thermal engineering
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| Research Institution | SCIENCE UNIVERSITY OF TOKYO |
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Principal Investigator |
TORIKAI KINICHI PROFESSOR, FACULTY OF SCI.&TECH., SCIENCE UNIV. OF TOKYO, 理工学部, 教授 (30164073)
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| Co-Investigator(Kenkyū-buntansha) |
SUZUKI KOHOICHI RESEARCH ASSOCIATE, FACULTY OF SCI.&TECH., SCI.UNIV.OF TOKYO, 理工学部, 助手 (10089378)
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| Project Period (FY) |
1984 – 1986
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| Project Status |
Completed (Fiscal Year 1986)
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| Budget Amount *help |
¥24,200,000 (Direct Cost: ¥24,200,000)
Fiscal Year 1986: ¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 1985: ¥8,000,000 (Direct Cost: ¥8,000,000)
Fiscal Year 1984: ¥8,200,000 (Direct Cost: ¥8,200,000)
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| Keywords | Boiling heat transfer / Transition boiling / Boiling bubble / Detachment of bubbles / Contact Area of Bubbles / 限界熱流束 / 熱工学 / 熱伝達 / 沸騰 / プール沸騰 / フレオンの沸騰 |
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| Research Abstract |
Heat transfer in transition boiling is much unstable and the details on mechanism of heat transfer are still one of the pending problems.
In the present study, the experimental research was performed for effects of roughiss of heating surface and fluid flow near the heating surface and a behavior of boiling bubbles on the heating surface to reveal an aspect of transition boiling. A large copper block was employed as thermal conductive body for the experiments of effects of surface roughness and fluid flow on water pool boiling. The copper block was heated by silicon carbide electric heater. A water jet was issued parallel to the heating surface from a flat nozzle located at one side of the surface. For observation of boiling bubbles, a thin transparent glass plate was employed as heating surface and was heated by high temperature heated liquid, silicon oil or fused salt, and freon R-11 was used for biling liquid. As results of experiment, the following interesting facts were found.
Compared with water pool boiling with smooth heating surface, heat flux in rough heating surface was higher and the characteristics was more stable. These facts were observed remarkably in high subcooling. In city water boiling, scale grown on the heating surface acted as a rough heating surface.
The fluid jet on the heating surface had a strong effect on bubble relases from heating surface, and coefficient of heat transfer decreased in nucleate boiling but increased in transition boiling and critical heat flux increased more than that of natural convective pool boiling.
According to the photographic observation of boiling bubbles, the ratio of bubble contacting area to total area of the heating surface was a little lower than that in water pool boiling for the same ratio of heat flux to critical heat flux.
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