Enhancement of Thermal Conductivity of Engine Coolant(HP Kool Gard )

Enhancement of Thermal Conductivity of Engine Coolant(HP Kool Gard) by use of

TiO2 Nanoparticles

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CONTENTS

• Introduction

• Properties of Coolant

• Methods of preparation of TiO2 nanofluid

• Procedure for preparation

• Evaluation of nanofluid properties

• Discussion

Introduction

• Thermo-physical properties of nanofluid are essential for the evaluation of heat transfer coefficient.

• These properties vary with concentration and temperature.

• The effect of variation of these parameters on thermo physical properties has been dealt by Masuda et al. (1993), Murshed et al. (2005), Zhang et al. (2007), Wang et al. (2002) and Dungthongsuk et al. (2009).

Properties of Coolant

• HP Kool Gard is a composition of ethylene glycol containing anti-corrosive and anti-freeze additives• The properties given in the specifications are :

Property Value

Density 1053.4 kg/m3

Boiling point 150 C

Freezing point(30 vol% water)

-14.5 C

pH(30 vol% water)

7 – 9

Methods for preparing TiO2 nanofluid

• TiO2 nanoparticles with an average size of 21nm, supplied by Sigma-Aldrich Chemicals Ltd, Germany has been used to prepare the nanofluid with water as the base fluid.

• Presently three methods are available for nanofluid preparation:

1. Direct mixing of nanoparticles to the base fluid

2. Mixing nanoparticles to base fluid in the acidic range

3. Use of surfactants to the base liquid.

Titanium-di-oxide nanoparticles

Procedure for preparation • The surfacant used here is CTAB(Cetyl

Trimethyl Ammonium Bromide)

• Nanofluid at different volume concentration in the range of 0.2% - 1.0% is prepared for property evaluation.

• To prepare TiO2 nanofluid of 0.2% concentration, for every 100 grams of coolant, 0.8104 grams of nanoparticles is to be mixed.

• Samples are first prepared by adding CTAB(0.1 times the weight of TiO2 nano particles) in different proportions to coolant and the mixtures stirred for 10 minutes.

• The nanoparticles are then added and stirred

continuously for 10 hours and the samples observed for dispersion and stability.

Preparation of nano fluid using surfacant

Evaluation of nanofluid properties

1. Density :• The density of nanofluid at different volume concentrations at room

temperature are calculated with

Where

Density of titanium di oxide, 4260 kg/m3

Density of coolant, 1053.4 kg/m3

Weight of sample coolant, 100 grams

wpnf 1

p

w

wW

2. Absolute viscosity :• Viscosity of nanofluid is estimated using

Redwood-1 viscometer at different volume concentrations and temperatures.

• The actual value absolute viscosity othe nanofluid is found from the equation

where µ in c.Poise, ρ in kg/m3, t in 0C • Wang et al. (1999) proposed a model for

calculating the viscosity of nanofluids theoretically which is defined as:

t

BAt

wfn 2.. 1233.71

Photograph of viscosity measuring instrument

3. Specific heat :• The specific heat of nanofluid at any concentration can be

estimated from the relation valid for homogeneous mixtures given by

• The specific heat calculated using the above equation is compared to the values obtained from the Pak and Cho equation given by

pw

ppwp

nfp

CCC

1

1

wpnfp CCC 1

4. Thermal Conductivity :• The effective thermal conductivity of

nanofluid at different volume concentrations is estimated using the thermal conductivity apparatus supplied by P.A. Hilton, U.K.

• The value of thermal conductivity of the nano fluid can be calculated from the equation :

Q = dT/dr

where Q is the electrical energy supplied is face area of fluid lamina dr is the thickness from the plug to the jacket

fluidk

Photograph of Thermal conductivity measuring instrument

Ldmfluidk

Ldm

• The value of thermal conductivity so obtained is then compared with the values of different researchers model. Few recent ones are shown :

1. Timofeeva et al. (2007) suggested the effective medium theory to calculate thermal conductivity of nanofluids, which is expressed as follows:

2. Murshed et al. (2006) developed a model for the effective thermal conductivity of nanofluids which shows a nonlinear nature.

31.. wfn kk

27.027.0

1

52.01

11

52.01127.01

3/13/1

3/4

3/13/4

.

w

p

w

p

w

p

wfn

k

k

k

k

k

k

kk

Discussion

• After finding the properties of the nanofluid we hope to

1. check wether the addition of nanoparticles increased the thermal conductivity of the base fluid.

2. check wether the results obtained are in good agreement with the measured data of the researchers.

3. find a new relation for calculating the properties of nanofluids.