1998 Fiscal Year Final Research Report Summary
Thermal Analysis and Evaluation of Absorption Enhancement of Falling Film Type Absorber by Using a Multi-pulsed Laser Holography
| Project/Area Number |
09650251
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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 |
Thermal engineering
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| Research Institution | Osaka City University |
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Principal Investigator |
NISHIMURA Nobuya Osaka City Univ., Faculty of Eng., Associate Professor, 工学部, 助教授 (30189310)
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| Co-Investigator(Kenkyū-buntansha) |
KASHIWAGI Takao Tokyo Univ.of Agriculture & Technology, Faculty of Eng., Professor, 工学部, 教授 (10092545)
IYOTA Hiroyuki Osaka City Univ., Faculty of Eng., Research Associate, 工学部, 助手 (10264798)
NOMURA Tomohiro Osaka City Univ., Faculty of Eng., Professor, 工学部, 教授 (50164736)
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| Project Period (FY) |
1997 – 1998
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| Keywords | Absorption Refrigerator / Absorber / Plate Type Heat Exchanger / Absorption Enhancement / Surfactant / Marangoni Convection / Laser Holography / Multi-pulsed Laser |
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| Research Abstract |
Absorption enhancement technologies by using a surface active agent were developed, involving both statical and dynamical experiments on absorption enhancement mechanisms, as well as the establishment of guidelines for the development of high-performance absorbers.
A first effort was made to visualize a Marangoni convection behavior with addition of n-octanol of LiBr aqueous solution in absorbers by a color high speed video camera (lOOOfps). Flow patterns of solution along the vertical direction were significantly different with and without n-octanol addition. When the surfactant was added, the film flow at the upper part of the absorber shows fully unconstructured chaotic behavior.
A further effort was made to clarify the basic mechanism for the inducement of Marangoni convection in the process of steam absorption into the pooled absorption solution of LiBr with addition of n-octanol as surface active agent. Real time type laser holographic interferometry was used to visualize the trans
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ient phenomena occurred at/beneath the LiBr aqueous solution's surface in the very beginning(O-20msec) of steam absorption under vacuum condition(O.7kPa). Experiments were performed varying the initial surfactant concentration from 0 to 200ppm and the liquid layer thickness of 3*5mm. Without n-octanol addition, interference fringes were scarcely seen. When n-octanol was added, complicated shapes of interference fringes were seen in the entire surface. Pentagonal or hexagonal cell's patterns were observed at the surface clearly. And those cells evolved from small to large size instantly. Thereafter large scale chaotic eddies were induced at the surface.
The results of this research indicated the following ; Addition of surfactant improves the refrigerating capacity about two times. Also the refrigerating capacity increases linearly with increasing of surfactant's concentration until its solubiity limit Vapor absorption from the absorbent surface is enhanced due to the occurrence of Marangoni convection in the thin falling film. Less
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Research Products
(12 results)
