Thermohydraulics of square-section microchannels following a serpentine path

Abstract

Fully developed laminar flow and heat transfer behaviour in serpentine channels with a square crosssection 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<R c /d<2 and 3.6<L/d<12 (where d is the side length of the square section, R c is radius of curvature of the serpentine bends, and L is the halfwavelength 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 R c /d mitigates these effects while the effect of increasing L/d decreases the frictional penalty without greatly affecting the heat transfer enhancement.

Investigation of fluid flow and heat transfer in wavy micro-channels with alternating secondary branches

“…This mechanism has been utilized by researchers for to boost heat transfer [10][11][12][13][14][15]. Numerical simulations conducted in the laminar flow regime show that Dean's vortices and more complex vertical flow profiles emerge when the working fluid negotiates through the curvature of the channel geometry [16][17][18][19][20][21]. The heat transfer capabilities could be greatly augmented; the ratio of the augmented heat transfer capability to pressure drop penalty incurred associated with the wavy channel design is superior to the conventional straight channel [16][17][18][19][20].…”

Fluid flow and heat transfer in wavy microchannels

“…This mechanism has been employed by many researchers for heat transfer enhancement [9][10][11][12]. Recently, Fletcher and co-authors [13][14][15][16][17] have numerically studied fully developed laminar flow and heat transfer in periodic serpentine channels with various cross-section shapes. It has been found that Dean vortices and more complex vertical flow patterns emerge when the liquid coolant is flowing through the bends.…”

Chaotic advection in steady laminar heat transfer simulations: Periodic zigzag channels with square cross-sections

“…There is no doubt that spatially periodic solutions exist for the flow at very low Reynolds numbers as demonstrated using the ''wrapping'' method in previous studies [13][14][15][16][17][18][19]. However, these showed that reverse-flow regions associated with sharp direction changes grew with increasing Reynolds number, to a point where there was backflow at the exit and the wrapping method could no longer be used.…”

“…We have recently examined fully-developed laminar flow and heat transfer in a variety of channel structures suitable for the application of plate-type heat exchangers, including serpentine [13][14][15][16], trapezoidal [17,18] and sinusoidal [19] channels of various geometrical configurations and cross-sections. High rates of heat transfer with comparatively low friction factors were largely attributed to the establishment of secondary flows in the form of Dean Re = 200).…”