Parametric study on heat transfer and pressure drop of twisted oval tube bundle with in line layout

Abstract

A numerical research is conducted to investigate air side heat transfer and pressure drop performance of twisted oval tube bundles with in line layout in cross flow. The effects of five geometric parameters (the ratio of outer major axis to outer minor axis (A/B), twist pitch length (S), transverse tube pitch (St), longitudinal tube pitch (Sl) and number of longitudinal tube rows (Z)) on the air side heat transfer and pressure drop performance are examined in the range of Reynolds number (Re) from 500 to 23,000. The velocity field and temperature field are repeated periodically every S/2 along the length of the twisted oval tube, which reveals that the twisted oval tube is a streamlined tube that is independent of the angle of attack. Twisted oval tube bundles perform excellent heat transfer performance compared with other tube bundles (circular tube bundle with the same tube layout as the twisted oval tube bundle, elliptic tube bundle with staggered manner, spirally corrugated tube bundle with in line layout) in cross flow. And the staggered tube layout is beneficial to enhance heat transfer performance compared with in line tube layout. Correlations for Nusselt number (Nu) and Euler number (Eu) from this paper are presented.