By suspending nanophase particles in heating or cooling fluids, the heat transfer performance of the fluid can be significantly improved. The main reasons may be listed as follows:
1.
The suspended nanoparticles increase the surface area and the heat capacity of the fluid.
2.
The suspended nanoparticles increase the effective (or apparent) thermal conductivity of the fluid.
3.
The interaction and collision among particles, fluid and the flow passage surface are intensified.
4.
The mixing fluctuation and turbulence of the fluid are intensified.
5.
The dispersion of nanoparticles flattens the transverse temperature gradient of the fluid.