An Introduction to the NanoFluid...Nanofluids are a relatively new class of fluids which consist of a base fluid with nano-sized particles (1–100 nm) suspended within them. It is

An Introduction to the

NanoFluid

By

Amin Behzadmehr

Hassan Azarkish

Introduction

Nanofluids are a relatively new class of fluids which consist of abase fluid with nano-sized particles (1–100 nm) suspended withinthem. It is introduced by choi on Argonne National Laboratory at1995.

-Heat Transfer Enhancement-Heat Transfer Enhancement

Comparison of the thermal conductivity of common liquids, polymers and solids.

(D. Wen et al. Particuology 7 (2009) 141–150)

Compared to conventional solid-liquid suspensions for heat transfer

intensifications, properly engineered thermal nanofluids possess the

following advantages:

1. High specific surface area and therefore more heat transfersurface between particles and fluids.

2. High dispersion stability with predominant Brownian motion of

Advantages of nanofluids

2. High dispersion stability with predominant Brownian motion ofparticles.

3. Reduced pumping power as compared to pure liquid to achieveequivalent heat transfer intensification.

4. Reduced particle clogging as compared to conventionalslurries, thus promoting system miniaturization.

5. Adjustable properties, including thermal conductivity andsurface wettability, by varying particle concentrations to suitdifferent applications.

Applications of nanofluids

•Transportation (Engine cooling/vehicle thermal management)

•Electronics cooling

•Defense

•Space

•Nuclear systems cooling•Nuclear systems cooling

•Heat exchanger

•Biomedicine

•Other applications (heat pipes, fuel cell, Solar water heating,

chillers, domestic refrigerator, Diesel combustion, Drilling,

Lubrications, Thermal storage,…)

Production of nanoparticles and nanofluids

NanoparticlesPhysical methods (Grinding methods, Inert Gas Condensation, …)Chemical methods (Chemical precipitation, Chemical Vapor Deposition,

Micro-emulsions, spray pyrolysis, thermal spraying,…)

NanofluidsNanofluidsThe one-step methodsimultaneously makes and disperse the nanoparticles directly into a base fluid

prevent oxidation of pure metal particles

non commercial

The two-step methodproduced the nanoparticles and dispersed them into a base fluid

Research and industrial applications

Researches

Experimental ResearchesThermal properties

Heat transfer correlations

Analytical ModelsAnalytical ModelsThermal properties

Similarity solutions

Numerical ResearchesSingle-phase

Two-phaseGrowth of publications by the nanofluids

community.

(D. Wen et al. Particuology 7 (2009) 141–150)

Convective heat transfer correlations for nanofluids.

Sampels of theoretical investigations in convective heat transfer of nanofluids.

Experimental research on nanofluid thermal conductivityEffect of particle volume concentration

W. Yu, D.M. France, S.U.S. Choi, and J.L. Routbort

Energy Systems Division, Argonne National Laboratory

Experimental research on nanofluid thermal conductivityEffect of particle material



Experimental research on nanofluid thermal conductivityEffect of particle size



Experimental research on nanofluid thermal conductivityEffect of particle shape



Experimental research on nanofluid thermal conductivityEffect of base fluid



Experimental research on nanofluid thermal conductivityEffect of temperature



Experimental research on nanofluid thermal conductivityEffect of PH



Nanofluids reported in literature

Experimental researches on heat transfer

Laminar flow




Turbulent flow




Natural convection

(N. Putra et al. Heat and Mass Transfer 39 (2003) 775–784)

Challenges of nanofluids

•lack of agreement of results obtained by different researchers

•lack of theoretical understanding of the mechanisms

responsible for changes in properties

•poor characterization of suspensions

•stability of nanoparticles dispersion•stability of nanoparticles dispersion

•Increased pressure drop and pumping power

•Nanofluids thermal performance in turbulent flow and fully

developed region

•Higher viscosity, Lower specific heat

•High cost of nanofluids

•Difficulties in production process

Stability of nanoparticles dispersion

Samples of Al2O3 nanofluids (without any stabilizer)

stability change with time

(R. Saidura et al. Renewable and Sustainable Energy Reviews 15 (2011) 1646–1668)

Stability of nanoparticles dispersion

The sedimentation of diamond nanoparticles at settling times of

(a) 0 min, (b) 1min, (c) 2min, (d) 3min, (e) 4min, (f) 5min, and (g) 6min

(R. Saidura et al. Renewable and Sustainable Energy Reviews 15 (2011) 1646–1668)

Nanoparticle agglomerates

(N. Putra et al. Heat and Mass Transfer 39 (2003) 775–784)

Part ‖

Research activities in nanofluidlaboratory

in Mechanical Engineering Department ofin Mechanical Engineering Department of

University of Sistan and Baluchestan

Researches

Numerical Works

Analytical Models

Experimental InvestigationsExperimental Investigations

Numerical Researches

� Single Phase approach

� Two-Phase approach

Single Phase approach

Two-Phase approach

� Mixture model

� Eulerian – Eulerian

� Eulerian-Lagrangian

Mixture model

Continuity

Momentum

Energy

Volume fraction

Eulerian – Eulerian

Continuity

Momentum Eq. in x directionMomentum Eq. in x direction


Momentum Eq. in y direction


Energy Equation

Eulerian-Lagrangian

Continuity

Momentum

Energy

Lagrangian for the particles

Some of the Numerical Results

Comparison of measured and calculated Nusselt numbers for a nanofluid flow.

Behzadmehr et al. 2007, International Journal of Heat & Fluid Flow, Vol.28, pp. 211-219

Some of the Numerical Results

Axial evolution of the centerline turbulent kinetic energy

Behzadmehr et al. 2007, International Journal of Heat & Fluid Flow, Vol.28, pp. 211-219

Fully developed peripheral average Nusselt number at different Grashof numbers: (a) Re = 300

(De = 83), (b) Re = 900 (De = 249).

Fully developed peripheral average skin friction coefficient at different Grashof numbers: (a) Re = 300

(De = 83), (b) Re = 900 (De = 249).

A. Akbarinia, A. Behzadmehr, 2007, Applied Thermal Engineering, Vol. 27, pp. 1327-1337

S. Mirmasoumi , A. Behzadmehr, 2008, International Journal of Heat & Fluid Flow, Vol. 29, pp.557-566

O. Gaffari, A. Behzadmehr, H. Ajam, 2010, International Communications in Heat and Mass Transfer 37 1551–1558

A new model for calculating the effective viscosity of nanofluids

Brownian motion, velocity between the base fluid and nanoparticles

Temperature, Mean nanoparticle diameter, Nanoparticle volume fraction,

Nanoparticle density and base fluid physical properties.

Analytical Models

N. Masoumi, N. Sohrabi, A. Behzadmehr, 2009, JOURNAL OF PHYSICS D: APPLIED PHYSICS 42

Comparison of the predicted relative

viscosity with the experimental and

other available models in the literature

for the Al2O3–H2O nanofluid at

(a) dp = 36 nm,

(b) dp = 28 nm

(c) dp = 13 nm.

Comparison of the predicted effective

viscosity with the experimental and

other available models in the literature

for the CuO–H2O nanofluid.

A Simple Analytical Model for Calculating the Effective ThermalConductivity of Nanofluids

•Conduction heat transfer caused by a solid-like nanolayer that covers

the nanoparticle.

•A convective heat transfer caused by the relative motion between the

Analytical Models

•A convective heat transfer caused by the relative motion between the

nanoparticle and the surrounding base fluid.

This equation presents the effective thermal conductivity as a function

of the thermal conductivity of nanoparticles, base fluid, nanoparticle

mean diameter, temperature, and solid-like nanolayer

N. Sohrabi, N. Masoumi, A. Behzadmehr, S.M.H. Sarvari, 2010, Heat Transfer - Asian Research Vol. 10, pp 141-150

Nanoparticle, nanolayer, and

surrounding base fluid arrangement.

Variations of the effective thermal conductivity with temperature:

(a) Al2O3–EG, (b) CuO–water

Experimental Investigations

� Single phase heat exchanger

� Boiling

� Stability

Thanks

Documents

An Introduction to the NanoFluid...Nanofluids are a relatively new class of fluids which consist of a base fluid with nano-sized particles (1–100 nm) suspended within them. It is