Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
Addition of nanoparticles is a known way to modify the behavior of a fluid in terms of heat transfer. This fact reaches its limits when it comes to natural convection. The aim of this paper is to show that the conventional characteristics to look at to choose a particle are no more the same for a phenomenon such as thermosyphon. Thus, the famous Alumina, compared thanks to tests and modeling, finds itself inferior to the low conductive Lithium Hydroxide in this configuration. Another aim of this article is to discuss the possibility to model nanofluids using single fluid approach and to show the limitations for long terms uses.