Experimental study on flow and heat transfer characteristics of SiC-water nanofluids in micro-cylinder-groups.

• Thermal conductivity of SiC-water nanofluids is measured by a 3ω method. • Flow and heat transfer characteristics in micro-cylinder-groups are investigated using SiC-water nanofluids. • Viscosity of nanofluid dominates heat transfer characteristics. • Flow and heat transfer characteristics are evaluated by thermal enhancement factor. With the rapid development of electronic industry, more attention has been paid to the structure of micro-cylinder-groups and nanofluids in recent years. The flow and heat transfer characteristics of SiC-water nanofluids at different volume fractions in micro-cylinder-group have been investigated experimentally. SiC-water nanofluids without dispersant at different volume fractions of 0.02%, 0.05%, 0.08%, 0.11% and 0.14% are prepared by a two-step method. The thermal conductivity is measured accurately by the 3ω method and the viscosity is measured by the rheometer. It is found that the friction factor decreases with the increasing Reynolds number due to the endwall effect and flow boundary layer, and the friction factor and the pressure drop increase with the increase of the volume fraction because of the interaction between nanoparticles and the wall. The results also confirm that the Nusselt number decreases as the volume fraction increases due to the increasing viscosity of SiC-water nanofluids. The Nusselt number increases with the increasing Reynolds number and the trend is generally consistent with the experimental results in the reference. It is also found that the thermal enhancement factor exceeds 1 when the volume fractions are 0.02% and 0.05% while it falls below 1 when the volume fraction increases to 0.08%, 0.11% and 0.14%. What's more, the thermal enhancement factor decreases with the increasing volume fraction, and the heat transfer performance is better at the volume fraction of 0.02%. [ABSTRACT FROM AUTHOR]