In summary, we derive an expression for the effective
thermal conductivity of nano fluids with interfacial shells.
Comparing with conventional models, the new expression is
not only depended on the thermal conductivity of the solid
and liquid and their relative volume fraction, but also depended
on the particle size and interfacial properties. Using
the model, we can easily understand the mechanism of
the particle size dependence of the thermal conductivity of
nano fluids. The theoretical results on the effective thermal
conductivity of CuO/water and CuO/EG nano fluids with interfacial
shells are in good agreement with the experimental
data.