Diffusion of Overheated and Overcooled Particles as a Mechanism of Thermal Conductivity in Nanofluids

A new mechanism of heat transfer in nanofluids is proposed on the basis of two physical principles: Brownian motion of particles in a fluid and thermal resistance of a particle—fluid interface. Owing to the thermal resistance of interfaces, the temperature of particles may differ from the temperature of the surrounding fluid; i.e., the particles may be superheated or supercooled. The diffusion of superheated or supercooled particles makes an additional contribution to the heat flux. It turns out that this contribution is negligible for the fluid with the inclusion of nanoparticles. At the same time, the contribution to the heat transfer by this mechanism is large and may be dominant for a gas with the inclusion of nanoparticles.