Thermal performance and entropy generation analyses of nanofluid flow in a trapezoidal heat sink with different arrangements

In this three dimensional study heat transfer characteristics and entropy generation of Alumina-water nanofluid laminar flow in a trapezoidal microchannel heat sink have been investigated numerically for a constant heat flux of 200 kW/m2 entering from the substrate and by considering conduction in solid parts. The main scope of this study has been investigating the effects of four horizontal inlet/outlets configurations, from different parts of the inlet and outlet chambers, on heat transfer characteristics and entropy generation, whereas the effects of the Brownian motion of nanoparticles and temperature-dependent properties of the nanofluid are considered. The results show that for a constant pressure drop increasing the nanoparticles volume fraction increases the Nusselt number and total entropy generation, while does not have impressive effect on thermal resistance and tetta (temperture uniformity of substrate). Also for a constant volume fraction increasing pressure drop increases Nusselt number, but decreases thermal resistance, tetta and total entropy generation. According to thermal idicators the A-type arrangment performs better. However, in terms of total entropy generation the B-type arrangement has a slightly better performance. In overall due to importance of tetta the A-type arrangement is the optimum arrangement.