Experimental study on preparation and base liquid effect on thermo-physical and heat transport characteristics of α-SiC nanofluids

Nanostructured solid particles dispersed in a base liquid are a new class of nano-engineered colloidal solutions, defined with a coined name of nanofluids (NFs). These fluids have shown potential to enhance heat transfer characteristics of conventional base liquids utilized in heat transfer application. We recently reported on the fabrication and thermo-physical property evaluation of SiC NF systems, containing SiC particles with different crystal structure. In this study, our aim is to investigate the heat transfer characteristics of a particular alpha-SiC NF with respect to the effect of alpha-SiC particle concentration and different base liquids on the thermo-physical properties of NFs. For this purpose, a series of NFs with various alpha-SiC NPs concentration of 3, 6 and 9 wt.% were prepared in different base liquids of distilled water (DW) and distilled water/ethylene glycol mixture (DW/EG). Their thermal conductivity (TC) and viscosity were evaluated at 20 degrees C. NF with DW/EG base liquid and 9 wt.% SiC NP loading exhibited the best combination of thermo-physical properties, which was therefore selected for heat transfer coefficient (HTC) evaluation. Finally, HTC tests were performed and compared in different criteria, including equal Reynolds number, equal mass flow rate and equal pumping power for a laminar flow regime. The results showed HTC enhancement of NF over the base liquid for all evaluation criteria; 13% at equal Reynolds number, 8.5% at equal volume flow and 5.5% at equal pumping power. Our findings are among the few studies in the literature where the heat transfer enhancement for the NFs over its base liquid is noticeable and based on a realistic situation. (C) 2014 Published by Elsevier Ltd.