As you rightly say, in bulk a metals electron transport can be very important, however the heat transfer in a nano-fluid will be limited primarily by the Kapitza resistance associated to the surface between the nano-particle and the fluid it is contained in.

As for publications, computer studies have mainly been of model classical systems and focus on the effects of the acoustic mismatch between the phonon modes in the nano-particle and fluid.

Theoretically, there are four modes of heat transport in nanofluids: collision between base fluid molecules, collision between nanoparticles due to brownian motion, interactions between particles and base fluid(nanolayer), and thermal transport in nanoparticles. Although electronic contribution is important in thermal transport of metallic nanoparticles, i think there is a little effect on thermal conductivity of nanofluids.

I agree with the above. Experiments show that metallic nanoparticles do not enhance heat conduction in nanofluids any better than metal oxide particles (insulators) in the limit of small volume fractions, where the heat transport (not conductivity) may be anomalous.

Thank you all guys

As i know, besides size, shape and concentration of nanoparticles (NPs), the interaction between NPs and base fluid is very important parameter.

What kind of interactions between base fluid and NPs in a typical nanofluid lead to a good enhancement in thermal conductivity of base fluid?

Generally one would expect the heat transfer to be most efficient in cases in which the wetting is strong, as in such cases the modes of collision in the nano-particle and fluid may more successfully couple.

Here is a paper which talks about the same type of concepts for a liquid solid intereface. The principles should be very similar for the case of a nano-fluid.

https://www.researchgate.net/publication/220042289_Kapitza_resistance_at_the_liquid---solid_interface

Article Kapitza resistance at the liquid---solid interface

Thank you so much Jeff