Numerical investigation of heat transfer and pressure drop for cooling of microchannel heat sink using MWCNT-CuO-Water hybrid nanofluid with different mixture ratio

Abstract

Micro-channel heat sinks are gaining prominent importance in cooling of micro-electronic devices due to their high rate of heat dissipation and very high surface area. Also during the recent times, hybrid nanofluids have appeared as a innovative group of working fluids for many heat transfer applications owing to special heat carrying characteristics. In view of the importance, a numerical study is carried out to examine the heat transfer and pressure drop characteristics for laminar flow of hybrid nanofluid as a coolant in a circular micro-channel heat sink (MCHS) under forced convection conditions in the present work. The performance of heat sink is evaluated using Multi-Walled Carbon Nano Tubes (MWCNT)-CuO/water based hybrid nanofluid for different mass flow rates, with the volume fractions ranging from 1% to 3%. The law of mixtures and correlations existing in the literature are used to find the properties of hybrid nanofluids. The influence of Reynolds number on pumping power and the heat transport rate is studied for different mixture ratios of MWCNT-CuO/water based hybrid nanofluids and similar studies were carried out for MWCNT-water and CuO-water mono fluids. The results show a step up in heat transfer with hybrid nanofluids over mono nanofluids and the enhancement of heat transfer is observed with raise in volume fraction. The maximum enhancement in Nusselt number was found at 3% of hybrid MWCNT-CuO/water nanofluid. An enhancement of 4.68% and 12.64% was found, when compared with CuO/water and MWCNT/water mono nonofluids respectively. The pressure drop results indicate that hybrid MWCNT-CuO/water nanofluid possess less pressure drop when compared to CuO/water nanofluids and when compared to water an increase of pressure drop of 300 Pa was found. This indicates that there is no significant increase in pumping power with hybrid nanofluids compared to mono-nanofluids and water. The present model is validated by comparing the numerical results got for mono nanofluid with the data available in literature.