Journal
INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
Volume 151, Issue -, Pages -Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijheatmasstransfer.2020.119473
Keywords
Twisted elliptical tube heat exchangers; Coupling-vortex; Parallel-vortex; Helical pitch; Chessboard square tube layout
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Funding
- National Science Foundation of China [51776035, 51976033]
- China Scholarship Council (CSC)
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The twisted elliptical tube heat exchangers with the novel coupling-vortex chessboard tube layout (TETHXs-CV) were simulated with the RNG kappa-epsilon model in software Fluent 15.0. The shell-side flow pattern at the tangential points between adjacent tubes in traditional TETHX is countercurrent while that in TETHX-CV is concurrent, which helps enhance heat transfer capability without any extra manufacturing cost. The impacts of the ratio A/B of the major axis to the minor axis and the twist pitch S were also investigated. The results indicate that with the increase of and the decrease of S, the secondary flow behaves more intensely, the Nusselt number Nu and the friction factor f increase, while with the increase of A/B and S, the comprehensive evaluation index Nu.f(-1/3) increases. The Nu, f and Nu.f(-1/3) of all twisted tube schemes are higher than those of the smooth round tube schemes R10.8. Compared with corresponding parallel-vortex schemes, the coupling-vortex schemes possess more uniform temperature fields, and the average Nu, f and Nu.f(-1/3) of the coupling-vortex schemes C12.3S50/C12.3S100 increase by 12.8%/9.9%, 15.2%/10.5% and 7.6%/6.3%, respectively; the smaller S or the closer A/B is to 1, the more advantageous the TETHX-CV. (C) 2020 Elsevier Ltd. All rights reserved.
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