A theoretical model for thermal conductivity of nanofluids

Nanofluid is modeled as a three-dimensional lattice structure. The model extends the use of Bridgman theoretical equation for the thermal conductivity of pure liquids, in addition to the concept of thermal resistances in parallel and series in heat transfer. The model does not include the thermal conductivity of the nanoparticle material and any fitting parameter; it requires the volume fraction of the nanoparticles and the fluid thermal conductivity in addition to the bulk modulus and density of the nanoparticles material. The results are compared with experimental data for eight different nanoparticle-fluid systems and found to compare favorably in most cases. The model results are also compared with Maxwell model, showing three fourths of the cases in which the present model is in agreement with experimental data versus one half of the cases for Maxwell model. The results seem to support the enhancement ratio mechanism by transfer of energy at the speed of sound of the nanomaterial through consecutive collisions between nanoparticles.