2006 Fiscal Year Final Research Report Summary
Enhancement of Convective Heat Transfer in Porous Media due to Joule-Thomson's effect and its Applications to Cooling of LSI Chips
| Project/Area Number |
17560190
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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 | Oita University |
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Principal Investigator |
KAMIUTO Koichi Oita University, Faculty of Engineering Department of Molecular Pathology, Professor, 工学部, 教授 (20038029)
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| Co-Investigator(Kenkyū-buntansha) |
SAITOU Shinichi Oita University, Faculty of Engineering, Research Associate, 工学部, 助手 (70253771)
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| Project Period (FY) |
2005 – 2006
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| Keywords | Thermal Engineering / Fluid Engineering / Joule-Thomson's Effect / Porous Media / Impinging Jet / Throttle / Cooling / CO_2 |
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| Research Abstract |
The results obtained in the present research project can be summarized as follows:
1. An analytical model of forced-convection heat transfer in packed beds taking into account the Joule-Thomson effect was presented and numerical analyses based on this model were performed to show that heat transfer enhancement occurs in a flowing medium having a positive Joule-Thomson's coefficient, whereas heat transfer deterioration occurs in a flowing medium having a negative Joule-Thomson's coefficient. It is also shown that these effects become appreciable with an increase in a ratio of pipe radius to mean particle diameter and/or Reynolds number.
2. CO_2 gas flow in an adiabatic packed bed results in cooling of the gas along the flow direction due to the Joule-Thomson effect. Since the pressure drop increase with a decrease in particle diameter and/or with an increase in Reynolds number, the temperature drop of CO_2 gas becomes appreciable in accord with a degree of the pressure drop. Moreover, one
… More
-dimensional packed-bed heat and fluid flow model derived from the above-mentioned theoretical model well reproduces the present experimental results of pressure and temperature gradients along the flow direction.
3. An analytical model describing temperature changes in a nonisoenthalpic throttling process was proposed and tested by experiments using CO_2, N_2 and H_2 gases. It is shown that the proposed model well predicts the experimental results.
4. To enhance cooling performance of electronic equipments such as LSI chips and thyristons, open-cellular porous materials are considered to utilize as a heat sink and are cooled by a circular nozzle with a flange. Ag, Cu, Ni and Ni-Cr porous plates having porosity from 0.86 to 0.96 and PPI from 7.4 to 111 and thickness ranging from 0.5 to mm were tested and N_2 and CO_2 gases were used as a coolant. Moreover, when CO_2 gas was tested, a nozzle settled a throttle upstream the exit was also used. We found that heat transfer enhancement is achieved for both N_2 and CO_2 gases as long as the thickness of a porous plate is less than 5mm and that, when a throttle was settled, about 60% heat transfer enhancement is obtained in comparison with no-throttle case. Less
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