Thermohydraulics of square-section microchannels following a serpentine path

Abstract

Fully developed laminar flow and heat transfer behaviour in serpentine channels with a square cross-section has been studied using computational fluid dynamics. Studies were performed up to Re=200, beyond which the flow became unsteady. The effect of geometric configuration was examined in detail for Re=110, 0.525<Rc/d<2 and 3.6<L/d<12 (where d is the side length of the square section, Rc is radius of curvature of the serpentine bends, and L is the half-wavelength of the serpentine path). Simulations were carried out at (Pr=0.7, 6.13 and 100) constant wall heat flux (H2 boundary condition) and constant wall temperature (T boundary condition). Dean vortices formed at the bends promote fluid mixing transverse to the main flow direction. This leads to significant heat transfer enhancement (up to a factor of 8 at high Pr and Re) with relatively small pressure-drop penalty (factor of 1.8 at high Re). Increasing Rc/d mitigates these effects while the effect of increasing L/d decreases the frictional penalty without greatly affecting the heat transfer enhancement.