Chapter 6: Thermal Conductivity of Nanofluids – Experiments, Models, and their Advancements

In this chapter, the main scientific activities and findings in connection with experiments and models for the determination of the thermal conductivity of nanofluids and their advancements are reviewed. The experimental investigation of nanofluids includes their preparation and characterization as well as the accurate measurement of their thermal conductivity. For the latter task, particular attention is paid to methods that are favorable for their application to nanofluids. In connection with the modeling of the thermal conductivity of nanofluids, the focus lies on theoretical approaches for the prediction of this property. Experimental and modeling results for the thermal conductivity of selected nanofluid types are analyzed as a function of influencing parameters and mechanisms, and are discussed in the context of the new advancements in the field. Here, the probably biggest advancement, which seems to be propagating steadily throughout the scientific community and has been pointed out in this chapter, is the finding that there is no anomalous or significant change in the thermal conductivity of fluids upon the addition of nanoparticles. This conclusion can be drawn from the application of suitable experimental techniques and models, which are often lacking in the literature.