0
Research Papers: Jets, Wakes, and Impingment Cooling

Influence of Microscale Surface Modification on Impinging Flow Heat Transfer Performance

[+] Author and Article Information
T. J. Taha

Thermal Engineering laboratory,
Faculty of Engineering and Technology,
University of Twente,
P.O. Box 217,
7500 AE Enschede,
Netherlands
e-mails: t.j.taha@utwente.nl;
taha.jibril.taha@gmail.com

L. Lefferts

Catalytic Processes and Materials,
Faculty of Science and Technology,
University of Twente,
P.O. Box 217,
7500 AE Enschede, The Netherlands

T. H. Van der Meer

Thermal Engineering Laboratory,
Faculty of Engineering and Technology,
University of Twente,
P.O. Box 217,
7500 AE Enschede, The Netherlands

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF HEAT TRANSFER. Manuscript received May 21, 2015; final manuscript received November 13, 2015; published online February 3, 2016. Assoc. Editor: Wilson K. S. Chiu.

J. Heat Transfer 138(5), 052201 (Feb 03, 2016) (10 pages) Paper No: HT-15-1351; doi: 10.1115/1.4032311 History: Received May 21, 2015; Revised November 13, 2015

An experimental approach has been used to investigate the influence of a thin layer of carbon nanotubes (CNTs) on the convective heat transfer performance under impinging flow conditions. A successful synthesis of CNT layers was achieved using a thermal catalytic vapor deposition process (TCVD) on silicon sample substrates. Three different structural arrangements, with fully covered, inline, and staggered patterned layers of CNTs, were used to evaluate their heat transfer potential. Systematic surface characterizations were made using scanning electron microscope (SEM) and confocal microscopy. The external surface area ratio of fully covered, staggered, and inline arrangement was obtained to be 4.57, 2.80, and 2.89, respectively. The surface roughness of the fully covered, staggered, and inline arrangement was measured to be (Sa = 0.365 μm, Sq = 0.48 μm), (Sa = 0.969 μm, Sq = 1.291 μm), and (Sa = 1.668 μm, Sq = 1.957 μm), respectively. On average, heat transfer enhancements of 1.4% and − 2.1% were obtained for staggered and inline arrangement of the CNTs layer. This is attributed to the negligible improvement on the effective thermal resistance due to the small area coverage of the CNT layer. In contrast, the fully covered samples enhanced the heat transfer up to 20%. The deposited CNT layer plays a significant role in reducing the effective thermal resistance of the sample, which contributes to the enhancement of heat transfer.

FIGURES IN THIS ARTICLE
<>
Copyright © 2016 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Structural arrangement of the deposited layer of CNT layer, with (a) fully covered, (b) inline arrangement, and (c) staggered arrangement. The area coverage of the CNT layer is represented by black color while the white portion represents the bare silicon. Each square represents an area of 100 μm2.

Grahic Jump Location
Fig. 2

Schematic flow diagram of impinging flow setup

Grahic Jump Location
Fig. 9

Effective thermal resistance analysis of the nanostructured surface compared to the bare sample

Grahic Jump Location
Fig. 3

SEM images of the different CNTs layer (a) fully covered surface, (b) Fe particles can be seen on the top of the fibers using energy selective backscatter electron detector, (c) staggered arrangement and (d) inline arrangement of CNTs

Grahic Jump Location
Fig. 4

Confocal microscopy of the nanostructured CNT layers with (a) fully covered, (b) inline arrangement, and (c) staggered arrangement of CNT layers. (d) Surface characterization results for the three different surface morphologies of the samples used.

Grahic Jump Location
Fig. 5

Contour plots of nozzle jet flow characteristics from the nozzle exit. ((a) and (c)) represents the normalized average velocity ( u¯/umax ) of the jet for the minimum and maximum jet flow rate used and ((b) and (d)) represents the turbulence intensity of the jet for the minimum and maximum jet flow rate used.

Grahic Jump Location
Fig. 6

Literature comparison of bare test samples with Huang and El-Genk [5], Huang [35], and Beitelmal et al. [36]

Grahic Jump Location
Fig. 7

Heat transfer enhancement results for the CNT samples with nozzle to plate spacing of (a) H/D = 1, (b) H/D = 2, (c) H/D = 4, and (d) H/D = 6

Grahic Jump Location
Fig. 8

Schematic diagrams for theoretical analysis of the effective thermal resistance of the sample

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In