Undulatory theory of phonons on the nanofluid thermal conduction

The present paper proposes a theoretical model for the prediction of the specific heat capacity and conductivity of nanofluids. The main control parameters of the model are sound velocity and thermal expansion coefficient of liquid and solid phases. The model also includes the thickness of the liquid wrapping the particles, in which it is relevant the thermal diffusion. Theoretical predictions were tested against the experimental data about the heat transfer in a nanofluid made by aluminum oxide nanoparticles, stably suspended in tap water. Thermal conductivity and heat capacity linearly change as function of the nanoparticle concentration. The molecular boundary layer develops towards the nanoparticle with the thermal expansion coefficient that changes linearly from zero at the particle surface up to the bulk value. The specific heat capacity does not have relevant effects due to the temperature variations. The temperature increasing induces a slight enhancement of the thermal conductivity because of the base fluid contribution.