Thermal conductivity variation for. methanol based nanofluids

Nanofluids refer to mixtures of solid nanoparticles suspended in base fluids. Nanofluids have gained popularity in heat transfer applications due to its attractive thermal characteristics. Thermal conductivity is one of the main parameters to which the applicability of nanofluids is attributed, as it affects the heat transfer coefficient. Three types of nanoparticles, namely Al2O3, SiO2 and TiO2 were suspended in methanol solution at five volume fractions (0.005%, 0.01%, 0.05%, 0.1% and 0.15%) in this work. Thermal conductivity was measured at five different temperatures (1, 5, 10, 15 and 20 degrees C) using a KD2 pro thermal conductivity meter. Thermal conductivity increases with the increase of volume fraction of nanoparticles for all types of nanoparticles investigated in this work. Enhancements between 1-8% occurred in thermal conductivities for every 0.05 vol% increase in nanoparticle volume fraction with Al2O3 having the highest enhancement. Thermal conductivity also increased between 0.5-3.9% for every 5 degrees C increment in temperature with SiO2 showing the least change. This study demonstrates that favorable thermal conductivity values and can be obtained for a specific type of nanoparticle at a specific temperature and volume fraction. Finally, a new correlation has been proposed for thermal conductivity of methanol based nanofluids in terms of volume concentration based on the experimental data. (C) 2014 Elsevier Ltd. All rights reserved.