An effective thermal conductivity model of nanofluids with a cubical arrangement of spherical particles.
The theoretical investigation of the effective thermal conductivities of nanofluids, a new class of solid-liquid suspensions, is important in both predicting and designing nanofluids with effective thermal conductivities. We have developed a new thermal conductivity model for nanofluids that is based on the assumption that monosized spherical particles are uniformly dispersed in the liquid and are located at the vertexes of a simple cubic lattice, with each particle surrounded by a liquid layer having a thermal conductivity that differs from that of the bulk liquid. This model nanofluid with a cubical arrangement of nanoparticles gives a more practical upper limit of thermal conduction than a model nanofluid with a parallel arrangement of nanoparticles. The new model unexpectedly shows a nonlinear relationship of thermal conductivity with particle concentration, whereas the conductivity-concentration curve changes from convex upward to concave upward with increasing volume concentration. The effects of particle and layer parameters on the effective thermal conductivities are also analyzed. A comparison of predicted thermal conductivity values and experimental data shows that the predicted values are much higher than the experimental data, a finding that indicates that there is a potential to further improve the effective thermal conductivities of nanofluids with more uniformly dispersed particles.
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Argonne National Laboratory, Energy Technology Division, 9700 S. Cass Avenue, Building 335, Argonne, Illinois 60439, USA.
Choi
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D006358:Hot Temperature; D015233:Models, Statistical; D008962:Models, Theoretical; D036103:Nanotechnology / Q000379:methods*; D013696:Temperature; D013814:Thermal Conductivity; D013817:Thermography