Simultaneous effect of staggered baffles and dispersed nanoparticles on thermal performance of a cooling channel

Abstract

This paper deals with laminar forced convection of Al2O3-water nanofluid in developing region of a channel with staggered baffles considering thermophoresis and Brownian motion. An extra scalar equation is considered along with other conservation equations to determine the dispersed nanoparticles distribution throughout the channel. The effect of nanoparticle concentration, Reynolds number and baffle height on the velocity and temperature fields, heat transfer rate, pressure drop and hydrothermal performance of the baffled channel is numerically investigated and the contours of nanoparticle distribution provided. The presence of nanoparticles results in a significant reduction in wall temperature, especially in dead regions in which hot spots are generated. Nanoparticle concentration decreases in recirculation regions and a wavy layer of the agglomerated nanoparticle is shaped exactly over the baffles. With decreasing Reynolds number, more non-uniform nanoparticle distribution is observed in baffled channel and the effect of nanofluid on temperature reduction becomes more pronounced. By addition nanoparticle into basefluid, the length and strength of recirculation flow decreases. Nanoparticles are of more significant effect on heat transfer enhancement and pressure drop increment when nanoparticle concentration and Reynolds number, respectively, rises and declines. The baffled channel presents a better hydrothermal performance for lower nanoparticle concentration and Reynolds number. As the baffle height is raised, more uniformity of nanoparticle distribution is observed in baffled channel and the influence of nanofluid on the wall temperature reduction in recirculation regions and reattachment points, respectively, increases and decreases. The computational results reveal that the impact of nanofluid on heat transfer and pressure drop augmentation depends on baffle height and an optimum value exists providing the best hydrothermal performance for baffled channel.