1994 Fiscal Year Final Research Report Summary
Fundamental Study of the Enhancement of Flash Evaporation in a Steam Accumulator by Means of the Injection of Artificial Bubble Nuclei
| Project/Area Number |
05650752
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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 |
化学工学一般
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| Research Institution | KYUSHU UNIVERSITY |
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Principal Investigator |
MIYATAKE Osamu Kyushu Univ., Faculty of Engng., Professor, 工学部, 教授 (70038579)
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| Co-Investigator(Kenkyū-buntansha) |
OMORI Hiromi Kyushu Univ., Faculty of Engng., Technical Official, 工学部, 教務員 (10260712)
NODA Hidehiko Kyushu Univ., Faculty of Engng., Research Associate, 工学部, 助手 (00112409)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Evaporation / Steam Accumulator / Evaporation Efficiency / Flash Evaporation / Enhancement / Bubble Growth / Artificial Nucleation / Electrolysis |
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| Research Abstract |
As an attempt to develop an efficient steam accumulator, an experimental investigation has been made of the effect injection of bubble nuclei generated by electrolysis on the flash evaporation of warm water exposed to a sudden pressure drop in a container.
From the results, it is realizad that artificial nucleation enhances the flash evaporation of pool water thereby increasing the flash evaporation efficiency in the late evaporaion period, especially for the cases of lower liquid temperature, higher liquid level and smaller superheat regions. Semi-empirical equations are deduced for predicting the practical evaporation efficiency when the mass velocity of vapor declined to any given values, from the dimensionless depth of the superheated zone ane the mass velocity of electrolytic gases.
Because bubble growth in a superheated liquid domains the flash evaporation process, a numerical analysis has been carried out to examine the effect of the initial bubble radius on the bubble growth rate in an uniformly superheated liquid. The results show that the effect of interfacial surface tension on the bubble growth rate can be neglected when the initial bubble radius is greater than two times of the critical radius. A dimensionless equation for predicting the bubble growth rate in uniformly superheated pure liquids is deduced from the theoretical solutions.
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