The nano-fluids are a uniform, stable and new type heat transfer working fluids prepared by adding metal or non-metallic nano-particles into liquid in some ways. This concept was first proposed in 1995 by Choi et al, in the U.S. Argonne National Laboratory. Comparied with the traditional heat transfer medium, nano-fluids have excellent features at the aspect of enhancing heat transfer. The nano-fluids with good stability and high heat transfer characteristics used in the energy, chemical engineering, metall...