1. R. HEYD CRMD/UMR 6619 – ORLÉANS/France LPN/ENS – Marrakech/Maroc FFSM/Cadi Ayyad University – Marrakech/Maroc ICNMRE SAFI/MOROCCO July 5-8 2010

2. The problem Liquids are used as heat carriers in: Solar hot water panelsDiesel engine

3. The problem Fourier’s law: How to combine: -flow properties of liquids & -high thermal conductivity of solid metals. Using a new class of nanocomposites: liquid/solid? LiquidsGlycerolWater (W/mK)0.300.58 MetalsIronCopperSilverCNT (W/mK)804004302500 Thermal conductivities, (λ) at RT.

4. Cuprite Nanoparticles/Nanofluid Cu 2 O nanoparticles: -Two extreme diameters were used: synthesized by reverse micelles at CRMD/Orléans (see poster for more details) purchased from Sigma-Aldrich

5. Cuprite Nanoparticles/Nanofluid Nanofluid synthesis: = Objectives: Test the influence of Cu 2 O NP on Glycerol’s transport properties, as a function of: -NP size -NP concentration Glycerol (biocompatible and anti-freezing liquid) + Cu 2 O nanoparticles in stable suspension

6. Rheological properties Experimental/Results – Kinexus rotational Rheometer – General Arrhenius Law:

7. Rheological properties Experimental/Results – Variations of relative viscosity with NP volume fraction at RT

8. Rheological properties Summary: -The addition of NP slightly increases the viscosity, -NP size has little influence, -The studied nanofluids tested exhibit the same general Arrhenius law as glycerol,  Viscosity increases with the NP volume fraction ϕ.

9. Thermal properties Experimental: technique Ref : Development of absolute hot-wire anemometry by the 3ω method, R. Heyd et al, 044901. In Review of Scientific Instruments 81 (4), 2010.

10. Thermal properties Results: Investigations of thermal conductivity and viscosity of nanofluids, S.M.S. Murshed, K.C. Leong, C. Yang, International Journal of Thermal Sciences 47 (2008) 560–568.

11. Thermal properties Results:

12. Thermal properties Summary: – Linear variation of the effective thermal conductivity of nanofluids with temperature, – Significant enhancement of the thermal conductivity with volume fraction and with NP size.

13. Conclusion & Perspectives The influence of increasing temperature on NP Brownian motion is: – Decreasing the viscosity of glycerol and consequently that of the nanofluid – Increasing the micro-convective contribution of the NP and consequently the thermal conductivity increases Influence of NP shape, size and interfacial layer on transport coefficients has to be taken into account. Investigation of electrical properties of nanofluids as a function of NP. Development of a microscopic model to better describe transport phenomena in nanofluids.