A small rectangular channel was designed and fabricated. The convective heat transfer properties of water-based graphene nanofluids in the channel were experimentally investigated by using it as the heat transfer medium under different experimental conditions [different mass concentrations, Reynolds numbers (Re) and heating powers], and some thermal properties of water-based graphene nanofluids were tested. The experimental results showed that the temperature along the wall of rectangular channel decreased with the increase of Re and increased with the increase of heating power under laminar flow (Re=500~1000). This change regulation was consistent with the heat transfer characteristics of conventional fluids, however, with the increase of mass concentration of nanofluids at same Re and heating power, the wall temperature decreased gradually because of the Brownian motion of graphene nanoparticles, the enhancement of scrambling by mixing of particles and the enhancement of thermal properties of nanofluids. The heat transfer intensity of water-based graphene nanofluid was higher than that of deionized water. When Re was 2000 and heating power was 210 W, the average Nusselt number (Nu) of water-based graphene nanofluids with 0.03wt% concentration was 9.3, which was 48.8% higher than that of the based water under the same conditions. Under the influence of inlet effect, the local convective heat transfer coefficient along the channel length decreased gradually, and the maximum local heat transfer coefficient of nanofluid increased by 39.1% compared with the deionized water. The flow heat transfer intensity of graphene nanofluids was obviously enhanced by the Brownian motion of graphene particles at certain Re (500~1400). In order to describe the heat transfer characteristics of water-based graphene nanofluids more clearly, a heat transfer relation was fitted by combining experimental data and theoretical models. Compared with the experimental results, the maximum relative error (MRE) was less than 25%, and the mean relative error was only 4.8%.
Dong LIU Yu SHU Anjie HU
. Fluid flow and heat transfer characteristics of water-based graphene nanofluids in small rectangular channels[J]. The Chinese Journal of Process Engineering, 2019
, 19(2)
: 289
-296
.
DOI: 10.12034/j.issn.1009-606X.218300
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