Performance investigation on twisted elliptical tube heat exchangers with coupling-vortex square tube layout

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TY - JOUR

T1 - Performance investigation on twisted elliptical tube heat exchangers with coupling-vortex square tube layout

AU - Gu, Huaduo

AU - Chen, Yaping

AU - Wu, Jiafeng

AU - Sunden, Bengt

PY - 2020

Y1 - 2020

N2 - The twisted elliptical tube heat exchangers with the novel coupling-vortex chessboard tube layout (TETHXs-CV) were simulated with the RNG k-ε 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 A/B 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.

AB - The twisted elliptical tube heat exchangers with the novel coupling-vortex chessboard tube layout (TETHXs-CV) were simulated with the RNG k-ε 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 A/B 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.

KW - Chessboard square tube layout

KW - Coupling-vortex

KW - Helical pitch

KW - Parallel-vortex

KW - Twisted elliptical tube heat exchangers

U2 - 10.1016/j.ijheatmasstransfer.2020.119473

DO - 10.1016/j.ijheatmasstransfer.2020.119473

M3 - Article

VL - 151

JO - International Journal of Heat and Mass Transfer

JF - International Journal of Heat and Mass Transfer

SN - 0017-9310

M1 - 119473

ER -