Final Report [electronic resource] : Use of Graphite Foam as a Thermal Performance Enhancement of Heavy Hybrid Propulsion Systems

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Tác giả:

Ngôn ngữ: eng

Ký hiệu phân loại: 629.89 Computer control

Thông tin xuất bản: Washington, DC : Oak Ridge, Tenn. : United States. Department of Energy Work for Others Program ; Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy, 2011

Mô tả vật lý: Medium: ED : , digital, PDF file.

Bộ sưu tập: Metadata

ID: 267529

Oak Ridge National Laboratory's graphite foam has the potential to be used as a heat exchanger for the Army's Future Combat System Manned Ground Vehicle and thus has the potential to improve its thermal performance. The computational fluid dynamics (CFD) program FLOW3D was used to develop a new CFD model for the graphite foam to be used in the development of a proper heat exchanger. The program was calibrated by first measuring the properties of the solid foams and determining the parameters to be used in the CFD model. Then the model was used to predict within 5% error the performance of finned foam heat sinks. In addition, the f factors and j factors commonly used to predict pressure drop and heat transfer were calculated for both the solid and finned structures. There was some evidence that corrugating the foams would yield higher j/f ratios than state of the art heat exchangers, confirming previously measured data. Because the results show that the CFD model was validated, it is recommended that the funding for Phases 2 through 5 be approved for the design of both the finned heat exchanger using tubes and round fin structures and the solid foam design using corrugated foams. It was found that the new CFD model using FLOW3D can predict both solid foam heat transfer and finned foam heat transfer with the validated model parameters. In addition, it was found that the finned foam structures exhibited j/f ratios that indicate that significant heat transfer is occurring within the fin structures due to aerodynamically induced flow, which is not present in solid aluminum fin structures. It is possible that the foam surfaces can act as turbulators that increase heat transfer without affecting pressure drop, like the vortex generators seen in state of the art heat exchangers. These numbers indicate that the foam can be engineered into an excellent heat exchanger. It was also found that corrugating the solid foams would increase the j/f ratio dramatically, allowing the solid foams to compete directly with standard heat exchangers. Although corrugated L1 foam samples have not been produced (attempts are under way), it is possible that their j/f ratio can be even higher than those of the finned structures.
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