Numerical Analysis of Heat Transfer and Fluid Flow through Twisted Hexagonal and Square Duct and their Comparisons

Abstract

The purpose of this study was to investigate the heat transfer and friction factor characteristics for hexagonal twisted duct. Numerical simulations were used to study the swirling flow inside a twisted duct of hexagonal cross section cooled by using counter flow in a shell and tube arrangement. Nusselt number and friction factor was calculated for a wide range of Reynolds number (Re) ranging from 1,000-1, 00,000. Laminar to turbulent transition point was identified. The results of twisted hexagonal duct were compared to that of twisted square duct. Results revealed that in the laminar regime, Nusselt number (NU) for hexagonal twisted duct is greater than that of square twisted duct, whereas in the turbulent region the corresponding Nusselt number for square twisted duct was greater than its hexagonal counterpart. However, in case of friction factor, a regular decrease in friction factor observed with increasing Reynolds number. The survey concluded that hexagonal ducts can be used in laminar flow regime and square ducts for turbulent flow regime. The impacts of the obtained results are practically applicable in power plant, aerospace, biomedical purposes.