Heat transfer and pressure loss characteristics of an offset fin with oblique waves

Abstract

An offset fin with oblique waves (OFOW) which is a combination of offset fin (OSF) and V-shaped oblique wavy fin (OWF) has been proposed to further enhance heat transfer in single phase laminar flows. The heat transfer and pressure loss characteristics of different configurations of the OFOW are investigated numerically. The 3D unsteady periodic model with the H1 thermal boundary condition is adopted to explore the effects of V wave pointing direction, phase angle and wave amplitude. The local distributions of velocity, secondary flow, wall shear stress and heat flux as well as friction factor f and Colburn factor j are presented and compared with those of the plain channel, OSF and OWF with the same aspect ratio and hydraulic diameter. It is found that the OFOW can further enhance heat transfer than the OSF and OWFs, i.e., at Re ≈ 400 with wave amplitude of A = 0.3, the Colburn factor j is around 4.2 times of that of the plain channel. It is shown that opposite V wave pointing directions in the successive offset plates cannot induce long-range counter-rotating vortices, and V wave amplitude A is the most dominant parameter, where wave pointing direction and phase angle in the successive offset plates have minor effects.