| Project/Area Number |
61550152
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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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 Professor, Dept. of Mat. Sci. & Chem. Engng., 工学部, 教授 (90005299)
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| Project Period (FY) |
1986 – 1987
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| Project Status |
Completed (Fiscal Year 1987)
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| Budget Amount *help |
¥1,800,000 (Direct Cost: ¥1,800,000)
Fiscal Year 1987: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1986: ¥1,300,000 (Direct Cost: ¥1,300,000)
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| Keywords | Thermal Engineering / Heat Transfer Augmentation / Boiling Heat Transfer / Fluid Vibration / Ultrasonic Wave / 膜沸騰伝熱 |
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| Research Abstract |
The effect of ultrasonic wave application on boiling heat transfer is investigated. A series of heat transfer experiments are carried out using a fine heater of a 0.20mm-dia. horizontal platinum wire, which is immersed in saturated ethylalxohol and exposed to a 28kHz ultrasonic wave. Little effect is obtained forrelatively high-heat-flux nucleate boiling heat transfer and the maximum heat flux point. The heat transfer coefficient of film boiling, on the contrary, increases with the increase of the power supplied to a ferrite type vibrator and it is doubled for the maximum in this experimental condition. The minimum heat flux point is also improved. At a lower superheat than the MHF line, nucleate boiling and film boiling coexist separately along the wire. Under a high power of the input, many bubbles begin to generate.
Interrelation between the ultrasonic wave intensity and the augmentation effect of film boiling heat transfer is studied.The intensity profile, which is measured by a ultrasonic wave probe with a piezo-type sensor, is proved to be like a sine wave function with half wave length of the ultrasonic wave. The maximum augmentation ratio is obtained at the position of the maximum intensity and a strong interrelation between them is proved. However, the experimental results also show that another cause to augment film boiling heat transfer will exist in addition to the ultrasonic wave intensity itself.
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