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Energies 2018, 11(6), 1550; https://doi.org/10.3390/en11061550

Flow Structure and Heat Transfer of Jet Impingement on a Rib-Roughened Flat Plate

1
Mechanical Power and Refrigeration Technology Department, College of Technological Studies, Shuwaikh Educational, P. O. Box 23167, Safat, Al-Asamah 13092, Kuwait
2
Advanced Centre for Technology, Tripoli, Libya
3
Department of Power and Propulsion, Cranfield University, Cranfield, Bedfordshire MK43 0AL, UK
*
Author to whom correspondence should be addressed.
Received: 5 May 2018 / Revised: 27 May 2018 / Accepted: 10 June 2018 / Published: 13 June 2018
(This article belongs to the Special Issue Fluid Flow and Heat Transfer)
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Abstract

The jet impingement technique is an effective method to achieve a high heat transfer rate and is widely used in industry. Enhancing the heat transfer rate even minimally will improve the performance of many engineering systems and applications. In this numerical study, the convective heat transfer process between orthogonal air jet impingement on a smooth, horizontal surface and a roughened uniformly heated flat plate is studied. The roughness element takes the form of a circular rib of square cross-section positioned at different radii around the stagnation point. At each location, the effect of the roughness element on heat transfer rate was simulated for six different heights and the optimum rib location and rib dimension determined. The average Nusselt number has been evaluated within and beyond the stagnation region to better quantify the heat transfer advantages of ribbed surfaces over smooth surfaces. The results showed both flow and heat transfer features vary significantly with rib dimension and location on the heated surface. This variation in the streamwise direction included both augmentation and decrease in heat transfer rate when compared to the baseline no-rib case. The enhancement in normalized averaged Nusselt number obtained by placing the rib at the most optimum radial location R/D = 2 was 15.6% compared to the baseline case. It was also found that the maximum average Nusselt number for each location was achieved when the rib height was close to the corresponding boundary layer thickness of the smooth surface at the same rib position. View Full-Text
Keywords: impingement heat transfer enhancement; orthogonal jet; turbulence; flat plate impingement heat transfer enhancement; orthogonal jet; turbulence; flat plate
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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).
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Alenezi, A.H.; Almutairi, A.; Alhajeri, H.M.; Addali, A.; Gamil, A.A.A. Flow Structure and Heat Transfer of Jet Impingement on a Rib-Roughened Flat Plate. Energies 2018, 11, 1550.

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