Paper presented to the 10th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Florida, 14-16 July 2014.
Nanofluids which are suspension of nanoparticles in conventional heat transfer fluids attracted researches on different heat transfer applications while they enhance thermal transport properties in comparison with conventional base fluids. Recently, utilizing these new fluids is growing increasingly, but the ambiguities of their thermal-physical properties cause to do not involve efficiently in the industrial design to date. The recognized important parameters effecting on properties of nanofluids include the volume fraction of the nanoparticles, temperature, nanoparticle size, nanolayer (thickness and properties), thermal conductivity of the base fluid, PH of the nanofluid, and the thermal conductivity of the nanoparticles. However, there is a distinct lack of enough investigation and reported research on the nanolayer thickness and its properties. In this work, the effect of uncertainty of the nanolayer thickness and properties on effective thermal conductivity and effective viscosity of nanofluids and as a result on heat transfer is discussed in details. The results show that the uncertainties can cause 20% error in calculation of Nusselts number and 24% for Reynolds number. Therefore, more investigation needs to be done into properties of nanolayer in order to identify them accurately.