University of Sistan and Baluchestan, Iranian Society Of Mechanical Engineers Challenges in Nano and Micro Scale Science and Technology 2821-000X 6 2 2018 07 03 Three dimensional numerical study on a trapezoidal microchannel heat sink with different inlet/outlet arrangements utilizing variable properties nanofluid 133 151 4043 10.22111/tpnms.2018.16509.1100 EN Hossien Khorasanizadeh University of Kashan Mojtaba Seperhnia Uni. of Kashan Journal Article 2016 09 23 Nowadays, microchannels as closed circuits channels for fluid flow and heat removal are an integral part of the silicon-based electronic microsystems. Most of previous numerical studies on microchannel heat sinks (MCHS) have been performed for a two-dimensional domain using constant properties of the working fluid. In this study, laminar fluid flow and heat transfer of variable properties Al2O3-water nanofluid in a trapezoidal MCHS, consisted of five trapezoidal microchannels have been studied. The three dimensional solution domains include the whole flow field and the complete MCHS solid parts. Four inlet/outlet arrangements, three pressure drops of 5, 10 and 15 kPa and nanoparticles volume fractions between 0 and 4% are assumed and the effects of these arrangements, properties variations and the Brownian motion on the heat sink performance quantified. The results indicate that the A-type heat sink, for which the inlet and outlet are placed horizontally at the center of the north and the south walls, has a better heat transfer performance, smaller thermal resistance and provides more uniform substrate temperature distribution. Temperature-dependent properties increases the heat transfer between 2.7% and 3.39%, decreases the thermal resistance between 3.49% and 6.29 % and decreases the ratio of difference between the maximum and minimum substrate temperatures to the heat flux between 3.3% and 7.19%. Presence of the Brownian motion showed a similar trend but with a slighter importance. https://chal.usb.ac.ir/article_4043_edf83b95f7ca85c16a294f27eb802a36.pdf