1997 Fiscal Year Final Research Report Summary
Fundamental Study on Micro-Actuator Utilizing Rapid Boiling
| Project/Area Number |
08455104
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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 | 一般 |
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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., Faculty of Engineering, Professor, 工学部, 教授 (90005299)
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| Co-Investigator(Kenkyū-buntansha) |
TAKASHIMA Takeo Yokohama National Univ., Faculty of Engineering, Asistant, 工学部, 助手 (40197091)
OKUYAMA Kunito Yokohama National Univ., Graduate school of Engineering, Ass.Professor, 工学研究科, 助教授 (60204153)
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| Project Period (FY) |
1996 – 1997
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| Keywords | Micro Actuator / Boiling Heat Transfer / Rapid Boiling / Spontaneous Nucleation / Small Film Heater / Unsteady State Boiling / Bubble Behavior / Evaporation |
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| Research Abstract |
The objective of this study is to reveal the boiling bubble behavior generated on a very small film heater or a fine wire immersed in pure liquids by heating them rapidly, since the behaviors are necessary for understanding and designing the micro-actuator which utilizes the liquid-gas phase change resulted from rapid boiling on the heater. A film heater whose dimensions were 0.1mm in width and 0.25mm in length was heated pulsewise by a direct current with a heating rate up to about 10^9K/s at the maximum and the temperature at the inception of boiling, the variation of nucleated bubble numbers, the aggragation process of tiny bubbles, the growth process and the collapse process of a bubble were measured and analyzed as well as the heat transfer behavior. Those succeeding the spontaneous nucleation were also examined. Thus, the bubble dynamics and the heat transfer characteristics when a very small film heater was heated rapidly were wholy revealed.
Further, with the aid of the above experimental results, the superheated liquid layr evaporation model was presented to explain theoretically the heat transfer and bubble behavior preceded by the rapid bubble nucleation on a heater. Experimental results as well as theoreticals showed that the maximum bubble volume decrased with the increase of the heating rate.
A series of observation experiments were carried out with a fine wire of 0.05mm in diameter for a very wide range of heating rate and it was shown that the bubble generation and collapse behaviors were divided roughly into 3 types in accordance with heating rate. Applicability of each type for a micro-actuator was discussed. Bubble nucleation in binary liquid mixtures was studied experimentally, since liquid mixtures was used instead of pure liquid in real micro-actuator.
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