| Project/Area Number |
10650193
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Fluid engineering
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| Research Institution | Kagoshima National College of Technology |
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Principal Investigator |
ESAKI Shuji Kagoshima Nat. Col. Tech., Dept. mech. Eng. Professor., 機械工学科, 教授 (40185111)
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| Co-Investigator(Kenkyū-buntansha) |
SHII Yasuyuki Kagoshima Nat. Col. Tech., Dept. mech. Eng., 機械工学科, 講師 (30270391)
NAKASHIMA Masahiro Kagoshima Nat. Col. Tech., Dept. mech. Eng. Professor., 機械工学科, 教授 (70124170)
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| Project Period (FY) |
1998 – 2001
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| Project Status |
Completed (Fiscal Year 2001)
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| Budget Amount *help |
¥1,700,000 (Direct Cost: ¥1,700,000)
Fiscal Year 2001: ¥700,000 (Direct Cost: ¥700,000)
Fiscal Year 2000: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 1999: ¥500,000 (Direct Cost: ¥500,000)
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| Keywords | Heat Exchanger / Heat Transfer Tube / Bubble / Falling Film / Gas Entrainment |
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| Research Abstract |
An experimental study was made to prevent the breakout of the heat exchanger tubes caused by the condensation of the steam bubbles which are entrained by the falling liquid film. Experiments were carried out in air-water system under the condition of atmospheric pressure. Experimental parameters considered were the flow rate of the falling liquid film on the inside of the tube, the distance "L" between the inlet of the falling liquid film and the liquid surface level in a test pipe where the falling liquid film flow into and the diameter of the test pipe. In this experiment, the length containing the gas entrainment under the liquid surface in the test pipe and the flow rate of the gas entrainment were measured. The axial distributions of the liquid film hold-up were also measured to clarify the relationship between the gas entrainment and the characteristics of the falling liquid film by using the constant current method. As the result, the following conclusions were obtained.
(1) Both the length containing the gas entrainment under the liquid surface where the falling liquid film flows into and the flow rate of the gas eatrainment increases with increasing the liquid film flow rate.
(2) Both the length containing the gas entrainment and the flow rate of the gas entrainment
depends on the distance "L" between the inlet of the liquid film and the liquid.surface where the liquid film flows into and increase with increased "L". However, these values begin to decrease at a certain value of "L" and then tend to increase again at the further value of "L".
(3) From the experimental results of the axial liquid film hold-up distributions, it is clear
that the interesting characteristics of the gas entrainment described above are occurred by two different factors, i.e., the average velocity of the falling film and the height of the natural
wave formed on the falling film.
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