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

The fluid flow and heat transfer behaviors in the novel sinusoidal micro-channels with secondary branches were examined both numerically and experimentally. Secondary branches, inspired by the oblique fin design were added in an alternating fashion (45) to the peaks and the troughs of the wavy micro-channel configuration to enable cross-channel mixing. Two designs with different amplitude of waviness were benchmarked against the optimal wavy channel configuration from the Reynolds number range of 50-200. An increase in heat transfer performance (when compared to the reference conventional wavy design) was observed when secondary branches were added, albeit with a pressure drop penalty. However, when another design with lower amplitude of waviness was introduced and compared to the reference geometry, superior heat transfer performance was observed without pressure drop tradeoff. The velocity and temperature profiles from the simulations were obtained to explain the hydrodynamic and heat transfer behaviors. The combination of Dean's vortices induced by the wavy channel design and the cross-channel mixing enabled by the secondary branches showed potential to further enhance convective heat transfer (at reasonable pressure drop penalties) due to the increased intensity of span-wise fluid mixing and also boundary layer disruptions. The attractiveness of the introduction of secondary branches lies in the potential to further enhance the heat transfer performance of the already established wavy channel configuration with minimal pressure drop penalty. (C) 2016 Elsevier Ltd. All rights reserved.