Influence of alternating V-rows tube layout on thermal-hydraulic characteristics of twisted elliptical tube heat exchangers.

• Coupling-vortex triangular tube layout is proposed without extra manufacturing cost. • Concurrent flow, larger A / B and smaller S cause stronger secondary flow. • The Nu and Nu · f −1/3 of C14.2S50 is 132.8% and 47.1% higher than R10.8. • Smaller S and smaller A / B lead to greater advantage of TETHXs-AVRCV. • The averaged Nu / Nu · f −1/3 of C12.3S50 are 7.8%/4.9% higher than those of P12.3S50. An innovative alternating V-rows triangular tube layout was devised for the twisted elliptical tube heat exchangers to enhance heat transfer between adjacent tubes. Under the same tube circumference, altogether eleven twisted elliptical tube heat exchangers with two tube layouts, diverse aspect ratios of twisted elliptical tubes and different twisted pitches were constructed and simulated, including five coupling-vortex schemes, five parallel-vortex schemes and a smooth round tube scheme R10.8. Water with constant physical properties was adopted as the working fluid. Shell-side Reynolds number varies from 2000 to 10,000. The results show that the concurrent flow and the irregular channel in coupling-vortex schemes, and the larger aspect ratio and the smaller twisted pitch of twisted elliptical tubes help intensify turbulence and secondary flow. Compared with R10.8, the averaged Nu and Nu · f −1/3 of coupling-vortex scheme C14.2S50 are improved by 132.8% and 47.1%, respectively. Under shorter twisted pitch, smaller aspect ratio and lower Reynolds number, coupling-vortex schemes can acquire superior heat transfer capability than corresponding parallel-vortex schemes but will not increase manufacturing cost. Compared with P12.3S50, the maximum and averaged Nu of C12.3S50 are increased by 9.5% and 7.8% while the maximum and averaged Nu · f −1/3 are increased by 6.4% and 4.9%. [ABSTRACT FROM AUTHOR]