Analysis of Brownian motion and particle size effects on the thermal behavior and cooling performance of microchannel heat sinks

In the present paper the thermal performance of nanofluid flow in microchannel heat sinks (MCHSs) was analyzed using three different nanofluids. The fluid flow and heat transfer in the MCHS are modeled using the Darcy–Brinkman–Forchheimer and two-equation model, respectively. In order to check the validity of the results, they were compared with available experimental and numerical data in the literature and excellent agreement was found between them. The key novelties of present work are (i) using a novel and complex temperature dependent thermal conductivity model for nanofluids, based on Brownian motion induced micro mixing, (ii) using new nanofluids with three types of nanoparticle materials i.e. aluminum oxide (Al2O3), zinc oxide (ZnO) and copper oxide (CuO) and 60:40 (by mass) EG–water for the base fluid, (iii) investigating the effect of nanoparticles size and Brownian motion of particles on thermal performance of MCHS.

► Performance of MCHS with 60:40 EG/W NFs was analyzed using a new thermal conductivity model. ► Effect of type of nanoparticles, volume fraction, particle size and Brownian motion were studied. ► CuO–H2O and Al2O3–H2O NFs lead to highest and lowest thermal performances, respectively. ► With decreasing particle sizes the thermal resistance of MCHS increases. ► The Brownian motion has significant effect on cooling performance of MCHS.