The thermofluid dynamic effects of ion injection from sharp metallic points added perpendicularly to the inner wire of a short horizontal annulus were experimentally investigated. A dielectric liquid (FC-72 by 3M) was weakly forced to flow in the duct, which was uniformly heated on the outer wall. A d.c. voltage as high as 22 kV was applied to the inner electrode, while the heated wall was grounded. Both the laminar and the turbulent mixed convection regimes were obtained, varying the imposed flow rate. Once an electric field is applied, the flow is dramatically modified by the jets of charged particles, which transfer their momentum to the neutral adjacent ones. Different injection strengths were obtained on the emitters, because the shape of the point tips was not controlled at the micro-scale. Nusselt number distributions were obtained azimuthally and longitudinally, monitoring the wall temperatures. In all cases, heat transfer turned out greatly enhanced in the proximity of the emitters, without a significant increase in pressure drop through the test section and with a negligible Joule heating, making this technique very attractive for application in compact heat exchangers.
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ASME 2004 Heat Transfer/Fluids Engineering Summer Conference
July 11–15, 2004
Charlotte, North Carolina, USA
Conference Sponsors:
- Heat Transfer Division and Fluids Engineering Division
ISBN:
0-7918-4692-X
PROCEEDINGS PAPER
Heat Transfer Augmentation by Ion Injection in an Annular Duct
Walter Grassi,
Walter Grassi
University of Pisa, Pisa, Italy
Search for other works by this author on:
Daniele Testi
Daniele Testi
University of Pisa, Pisa, Italy
Search for other works by this author on:
Walter Grassi
University of Pisa, Pisa, Italy
Daniele Testi
University of Pisa, Pisa, Italy
Paper No:
HT-FED2004-56625, pp. 261-268; 8 pages
Published Online:
February 24, 2009
Citation
Grassi, W, & Testi, D. "Heat Transfer Augmentation by Ion Injection in an Annular Duct." Proceedings of the ASME 2004 Heat Transfer/Fluids Engineering Summer Conference. Volume 3. Charlotte, North Carolina, USA. July 11–15, 2004. pp. 261-268. ASME. https://doi.org/10.1115/HT-FED2004-56625
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