R. HEYDCRMD/UMR 6619 – ORLÉANS/France

LPN/ENS – Marrakech/MarocFFSM/Cadi Ayyad University – Marrakech/Maroc

ICNMRE SAFI/MOROCCO

July 5-8 2010

The problemThe problem

• Liquids are used as heat carriers in:

Solar hot water panelsDiesel engine

The problemThe 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?

Liquids Glycerol Water

(W/mK) 0.30 0.58

Metals Iron Copper Silver CNT

(W/mK) 80 400 430 2500

Thermal conductivities, (λ) at RT.

Cuprite Nanoparticles/NanofluidCuprite Nanoparticles/Nanofluid

• Cu2O nanoparticles:- Two extreme diameters were used:

synthesized by reverse micelles at CRMD/Orléans (see poster for more

details)

purchased from Sigma-Aldrich

Cuprite Nanoparticles/NanofluidCuprite Nanoparticles/Nanofluid

• Nanofluid synthesis:

=

• Objectives: Test the influence of Cu2O NP on Glycerol’s transport properties, as a function of:

- NP size- NP concentration

Glycerol (biocompatible and anti-freezing liquid)

+Cu2O nanoparticles in stable suspension

Rheological propertiesRheological properties• Experimental/Results– Kinexus rotational Rheometer– General Arrhenius Law:

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

Rheological propertiesRheological 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.

Thermal propertiesThermal 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.

Thermal propertiesThermal 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.

Thermal propertiesThermal properties• Results:

Thermal propertiesThermal 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.

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.