Intriguingly high thermal conductivity increment for CuO nanowires contained nanofluids with low viscosity

Abstract

Nanofluids offer the exciting new possibilities to enhance heat transfer performance. In this paper, experimental and theoretical investigations have been conducted to determine the effect of CuO nanowires on the thermal conductivity and viscosity of dimethicone based nanofluids. The CuO nanowires were prepared through a thermal oxidation method, and the analysis indicated that the as-prepared CuO nanowires had high purity, monocrystalline with a monoclinic structure and large aspect ratio compared to CuO nanospheres. The experimental data show that the thermal conductivity of the nanofluids increases with the volume fraction of CuO nanowires or nanospheres, with a nearly linear relationship. For the nanofluid with the addition of 0.75 vol.% CuO nanowires, the thermal conductivity enhancement is up to 60.78%, which is much higher than that with spherical CuO nanoparticles. The nanofluids exhibit typical Newtonian behavior, and the measured viscosity of CuO nanowires contained nanofluids were found only 6.41% increment at the volume fraction of 0.75%. It is attractive in enhanced heat transfer for application. The thermal conductivity and viscosity of CuO nanofluids were further calculated and discussed by comparing our experimental results with the classic theoretical models. The mechanisms of thermal conductivity and viscosity about nanofluids were also discussed in detail.

Silver Nanowires Contained Nanofluids with Enhanced Optical Absorption and Thermal Transportation Properties

“…In our previous work, we studied the effect of temperature on viscosity, the experimental findings exhibited that viscosity of 0.75% CuO nanofluids reduces with the increase of temperature. At the temperature of 65 °C, viscosity of the CuO nanowires contained nanofluids decreases by 40% . In fact, for Newtonian nanofluid, all the research results show that viscosity will decrease with increasing temperature for the same nanofluid.…”

A Comparative Evaluation of Physicochemical Properties and Photocatalytic Efficiencies of Cerium Oxide and Copper Oxide Nanofluids

“…where k is thermal conductivity, N is Avogadro's number and V is ultrasonic velocity. The thermal conductivity of the two studied NFs increases with the respective NP concentration [34]. Brownian motion of suspended nanoparticles is considered as the major key factor for the noticeable enhancement of thermal conductivity with the nanoparticle addition.…”

“…The enhancement in the thermal conductivity has been investigated for CuO-ethylene glycol NFs [33]. CuO/dimethicone NFs were prepared with CuO nanowires and spherical NPs and thermal conductivity increments were critically evaluated based on the influence of nanomorphology [34]. With respect to CuO NFs, there are limited reports available based on NFs prepared in a range of conditions [10,[35][36][37][38][39].…”

Influence of polymer washing on thermal conductivity enhancement of Cu nanofluids

“…Moreover, the shape of nanostructures is also an important parameter in enhancing thermal properties of base fluid. Recently, Zhu et al claimed that CuO nanofluids prepared by dispersing nanowires in base fluid are exhibiting higher thermal conductivity (~60%) compared with nanofluid synthesized using nanospheres 16 . An extensive work has been conducted on preparation of alumina (Al 2 O 3 ), 17 copper oxide (CuO), 18 titanium dioxide (TiO 2 ), 19 silver (Ag), 20 gold (Au), 21 iron oxide (Fe), 22 and carbon nanotube‐based nanofluids 23 for its application in the enhancement of thermal and rheological properties of base fluids.…”