Comparative study of characteristics of water-ethanol binary mixture nanofluids for heat pipe efficiency enhancement

A nanofluid is a fluid containing suspended solid particles, with sizes on the order of nanometers. Normally, nanofluids have higher thermal conductivities than their base fluids. Therefore, we manufactured binary nanofluids by adding multi-walled carbon nanotubes to water-ethanol (ethanol concentration is 0.2) binary mixture nanofluids for efficiency improvement of a heat pipe. And we measured the thermal conductivity and viscosity of water-ethanol binary mixture nanofluids. The thermal conductivity and viscosity of binary nanofluids were measured by using transient hot-wire method and rotational digital viscometer, respectively. As a result, at the same volumetric ratio and temperature, the water-ethanol binary mixture nanofluids offer a lower rate of viscosity increase and a higher rate of thermal conductivity increase than distilled-water-based nanofluids. Therefore, nanofluids, formulated based on binary fluids mixed to the proper ratio, offer excellent performance that is clearly superior to that of single-component-based nanofluids. (C) 2014 AIP Publishing LLC.