1995 Fiscal Year Final Research Report Summary
Control of Heat Transfer and Defrostings with Fluidized Beds
| Project/Area Number |
06044018
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| Research Category |
Grant-in-Aid for international Scientific Research
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| Allocation Type | Single-year Grants |
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| Section | Joint Research |
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| Research Institution | TOHOKU UNIVERSITY |
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Principal Investigator |
AIHARA Toshio Institute of Fluid Science, Tohoku University, Professor, 流体科学研究所, 教授 (90006172)
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| Co-Investigator(Kenkyū-buntansha) |
UWE Schaflin ウィーン工科大学, 流体力学熱伝達研究所, 助教授
WILHELM Schn ウィーン工科大学, 流体力学熱伝達研究所, 教授
INNAMI Yukio Institute of Fluid Science, Tohoku University, Associate, 流体科学研究所, 助手 (50271987)
OHARA Taku Institute of Fluid Science, Tohoku University, Associate Professor, 流体科学研究所, 助教授 (40211833)
YAMADA Masahiko Dept. of Mechanical Eng., Hokkaido University, Associate Professor, 工学部, 助教授 (70230480)
FUKUSAKO Shoichiro Dept. of Mechanical Eng., Hokkaido University, Professor, 工学部, 教授 (00001785)
SCHAFLINGER Uwe Institute of Fluid Dynamics and Heat Transfer, Technical University, Vienna, Ass
SCHNEIDER Wilhelm Institute of Fluid Dynamics and Heat Transfer, Technical University, Vienna, Pro
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| Project Period (FY) |
1994 – 1995
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| Keywords | Fluidized bed / Impinging jet / Heat-transfer control / Frosting control / Cooled tube array |
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| Research Abstract |
In the cases where conventional finned-tube heat exchangers are used as evaporators in heat pump systems and LNG-gasification systems, moisture in humid air freezes and forms a thick frost layr on the fin surfaces, which reduces the heat transfer, increases the pressure loss, and finally results in choking of the evaporatores. Thus development of frost-free evaporators is an important and urgent research subject. The present research project has been performed to study heat and mass transfer characteristics of impinging jet-type fluidized bed and its defrosting characteristics. The obtained results are useful to establish a fluidized-bed heat exchanger which is effective for defrosting.
Results of the Joint Research
In Tohoku University, the following experimental studies were performed :
(1) Study on local heat transfer and frosting characteristics of cold tubes in single-phase impinging jets.
(2) Study on defrosting mechanism of a very shallow fluidized bed, measurement of particle's con
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tact frequency onto the tube surface, and observation of the behavior of particles on the tube surface.
(3) Study on heat transfer characteristics of cold tubes under defrosting by particle impingement.
In Hokkaido University the following experimental studies were performed :
(1) Study on heat transfer charactersistics of impinging-jet type fluidized ged. Especially the effect of fluidizing particles on heat transfer in a powder-mixed fluidized bed.
(2) Study on freezing and continuous production characteristics of liquid ice by use of the fluidized bed.
(3) Study on frosting characteristics of a vertical cooled plate and a horizontal cooled tube array immersed in a fluidized bed.
(4) Study on melting heat transfer characteristics of a horizontal cooled tube array immersed in liquid ice.
In Technical University, Vienna, theoretical study on formation process of particle-gas jets and their impingement onto tube surface was performed especially for the cornice-type distributor, utilized in Tohoku University.
By joining these results of the above-mentioned studies, an potimum design method for impinging-jet type fluidized bed has been established. Also the heat-transfer and defrosting characteristics and the control theory for them were clarified, which is useful for practical applicatios. Less
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