1994 Fiscal Year Final Research Report Summary
Enhancement of Mass Transfer into a Falling Liquid Film by Two-Dimensional Waves
| Project/Area Number |
05650201
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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 | UNIVERSITY OF RYUKYUS |
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Principal Investigator |
NAGATA Takashi University of the Ryukyus, Dept. of Mechanical Systems Engineering, 工学部, 教授 (70045186)
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| Co-Investigator(Kenkyū-buntansha) |
NOSOKO Takehiro University of the Ryukyus, Dept of Mechanical Systems Engineering, 工学部, 助教授 (80183903)
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| Project Period (FY) |
1993 – 1994
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| Keywords | Liquid Film / Surface Wave / Gas Absorption / Mass Transfer / Liquid Film Type Absorber / 液膜式吸収器 |
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| Research Abstract |
Two-dimensional waves are excited on a falling laminar water film with input of controlled disturbances. and the augmentation in absorption rate of the film from the surrouding gas by the waves are experimentally determined at the room temperature. Two-dimensional waves appear on the whole surface of the film in the range of wave frequencies 10-30Hz, and otherwise waves coalesce with each other to become three dimensional. The augmentation decreases momotonecally with wave frequency at low Reynolds numbers Re<20. while increases at high Reynolds numbers Re>20. Two-dimensional waves increase in absorption rate with Reynolds number. and the rate becomes 2.5 times larger than the values for flat surface films at Reynolds numbers Re>50.
Taking account of these results and the numerical observations by Nagasaki and Hijikata (1990) and others, the double boundary layr model is built up, inwhich the mass transfer coefficient alpha is expressed as alpha=xiROO<3.46Dlpif_w>, where D and f_w are diffusivity and wave frequency, introducing the parameter for sweeping motion of high concentration layr near the surface by the waves xi. It is found that the parameter is a function only of wave velocity at the given physical properties of the liquid and increases monotonically with wave velocity.
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Research Products
(3 results)
