ADVANCE COOLING OF RADIATORS BY

USING COPPER-OXIDE NANOFLUIDS P.Suganya,

Assistant Professor, Department of Aeronautical Engineering,

Hindusthan College of Engineering and Technology,

Coimbatore, India.

G.Subburaj, S.Ragupathy, T.Ajith, K.Vinothkambly,

Student,Department of Aeronautical Engineering,

Hindusthan College of Engineering and Technology,

Coimbatore, India.

subburaj5975@gmail.com

Abstract - Current radiator designs are limited by

requiring a large frontal area to meet cooling needs.

Nowadays water and ethylene glycol have been used as

a conventional coolants in an automobile radiator for

many years. These heat transfer fluids offer low

thermal conductivity and poor heat transfer

characteristics. The development of advanced

nanofluids, which have better conduction and

convection thermal properties has a new opportunity to

design a high energy efficient, light-weight radiator.

This project will explore concepts of next-generation

radiators that can adopt the high performance

nanofluids.

Keywords: Nanofluids, Radiator, Cooling, Thermal

Conductivity, Efficiency

I. INTRODUCTION

The automotive industry is continuously

involved in a strong competitive career to obtain the

best automobile design in multiple aspects

(performance, fuel consumption, safety, etc.). The air-

cooled heat exchangers found in a vehicle (radiator,

AC condenser and evaporator, etc.) have an important

role in its weight and also in the design of its frontal

area. The use of nanofluids as coolants would allow for

smaller size and better weight reduction of the

radiators[1]. The use of high-thermal conductive

nanofluids in radiators can lead to a reduction in the

frontal area of the radiator up to 10%. The fuel saving

is up to 5% due to the reduction in aerodynamic drag.

Nanofluids have great potentials to improve

automotive and heavy-duty engine cooling rates by

increasing the efficiency, lowering the weight and

reducing the complexity of thermal management

systems. The improved cooling rates for automotive

and truck engines can be used to remove more heat

from higher horsepower engines with the same size of

cooling system. Alternatively, it is beneficial to design

more compact cooling system with smaller and lighter

radiators. It is in turn benefit the high performance and

high fuel economy of car and truck. Ethylene glycol or

water based nanofluids have attracted much attention

in the application as engine coolant, due to the low-

pressure operation compared with a 50/50 mixture of

ethylene glycol and water, which is universally used

automotive coolant.

The nanofluids has a high boiling point, and it

can be used to increase the normal coolant operating

temperature and then reject more heat through the

existing coolant system. These novel and advanced

concepts of coolants offer better heat transfer

characteristics compared to conventional coolants.

Eastman et al [4], Liu et al.[5], Hwang et al.[6], Yu et

al[7]. And Mintsa et al.[8] , observed great

enhancement of nanofluids, thermal conductivity

compared to conventional coolants. Enhancement of

convective heat transfer was reported by Zeinali Heris

et al.[9] , Kim et al., Jung et al.[10] and Sharma et

al.[11] . This paper review application of Copper-

Oxide Nanofluids as coolant in Automobile radiator.

II. RADIATOR

Radiators are Heat exchangers used to

transfer thermal energy from one to another medium

for the purpose of cooling or heating. A fluid flowing

through array of pipe where heat is transferred from

one fluid to another. The proper design, operation and

maintenance of heat exchangers will make the process

energy efficient and minimize energy losses [23].

Coolant path and Components of an Automobile Engine Cooling System

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There are three basic modes of heat transfer

occurring in radiator which are conduction,

convection, radiation. Conduction takes places

between radiator tubes and fins. Most of the convection

because of air flowing around the radiator fin and tube

assembly and remaining due to the coolant flowing

through the radiator tubes. Radiation occurs

everywhere so we only focused about conduction and

convection heat transfer.

III. NANOFLUID

Nano fluid is a fluid containing nanometer-

sized particles, called nanoparticles. These fluids are

engineered colloidal suspensions of nanoparticles in a

base fluid.

Nanofluid = Basefluid + Nanoparticle

Nanoparticle is defined as a small object that behaves

as a whole unit with respect to its transport and

properties. Particles are further classified according to

diameter.

Coarse particles (10,000 to 2,500 nm)

Fine particles (2,500 to 100 nm)

Ultrafine particles (1 to 100 nm)

The nanoparticles used in Nano fluids are typically

made of metals, oxides, carbides

Common base fluids include water, ethylene glycol

and oil.

A. PREPARATION OF NANOFLUIDS

There are two fundamental methods to obtain

Nanofluids[3]:

1. Single-step direct evaporation method: In this

method, the direct evaporation and condensation of the

nanoparticulate materials in the base liquid are

obtained to produce stable nanofluids.

2. Two-step method: In this method, first the

nanoparticles are obtained by different methods and

then are dispersed into the base liquid.

B. OVERVIEW OF NANOFLUIDS

In automotive systems where improved heat

transfer could lead to smaller heat exchangers for

cooling resulting in reduced weight and size of the

vehicle. Many methods are available to improve heat

transfer in processes. The flow of heat in a process can

be calculated based on [14]

Q = hAT

Where,

Q is the heat flow,

h is the heat transfer coefficient,

A is the heat transfer area, and

T is the temperature difference in heat flow

It can be stated from this equation that increased heat

transfer can be achieved by:

i) Increasing T,

ii) Increasing A,

iii) Increasing h

A greater temperature difference T can lead

to increase the heat flow, but T is often limited by

process or materials constraints. Therefore, T

increased can only be achieved by decreasing the

temperature of the coolant[14].

Maximizing the heat transfer area A is a

common strategy to improve heat transfer, and many

heat exchangers such as radiators and plate-and-frame

heat exchangers are designed to maximize the heat

transfer area. In aerospace and automotive systems,

increasing the heat transfer area can only be achieved

by increasing the size of the heat exchanger which can

lead to unwanted increases in weight[14].

Heat transfer improvements can also be

achieved by increasing the heat transfer coefficient h

either by using more efficient heat transfer methods, or

by improving the transport properties of the heat

transfer material. For example, heat transfer systems

which employ forced convection of a gas exhibit a

greater heat transfer coefficient than systems which

employ free convection of a gas. Alternatively, the heat

transfer coefficient can be increased by enhancing the

properties of the coolant for a given method of heat

transfer. Additives are often added to liquid coolants to

improve specific properties. For example, glycols are

added to water to depress its freezing point and to

increase its boiling point. The heat transfer coefficient

can be improved via the addition of solid particles to

the liquid coolant (i.e. nanofluids).[14-22]

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Thermal conductivity of various Materials (at

300K) [13]

C. WHY WE USE NANO FLUID?

The main goal or idea of using nano fluids is

to attain highest possible thermal properties at the

smallest possible concentrations (preferably

Properties of air at 35C, HMT data book p.no:34

Density () = 1.1465kg/m3

Kinematic viscosity (v) = 16.48X10-6m2/s

Prandtl number (p r) = 0.7

Thermal conductivity(k) = 0.027155w/mk

Reynolds number ( Re) = (UD)/v

= (21.98X0.3)/(16.48X10-6)

Re = 4.001X105

Nusselt Number (Nu) = c(Re)m(Pr)0.333

From HMT data book page No 1.116 for Re value is

4.001X105, corresponding C value is 0.911 and m

value is 0.385

Nusselt Number

Nu = (0.911)X(4.001X105)0.385X(0.7)0.333

Nu = 116.08

Nu = (hD)/k

116.08 = (h*0.3)/0.027155

h = 1282.41 w/m2k

Heat Transfer (Q) = hA(Tw-T)

= (1282.41)X(3.14X0.006X1.5)X(50-20)

Q = 1087.78w

V. PROCEDURE

A. SCHEMATIC OF EXPERIMENTAL SETUP

First the pure water is heated in the tank by

using the water heater. Then the heated water is sent in

to the radiator for cooling. The inlet and outlet

temperature was measured in the digital thermometer

for calculations. Then the procedure was repeated for

the CuO Nano fluid.

B. EFFICIENCY

Efficiency = (Twi-Two)/( Twi-Twba)

Where,

Twi = Temperature of Inlet,

Two = Temperature of outlet,

Twba = Temperature of atmosphere.

C.OBSERVATION

For Pure water Inlet temp: 500c

Outlet temp: 430c

Efficiency = (50-43)/(50-27) * 100

= 30.43%

For Nano fluid(CuO) Inlet temp: 500c

Outlet temp: 33.50c

Efficiency = (50-33.5)/(50-27) * 100

= 71.73%

TABLE1. COMPARISON

PROPERTIES PUREWATER NANOFLUID

Thermal conductivity

Low high

Viscosity Low High

Density Low High

Efficiency 30% 70%

Stability Low High

Preparation Does not requires

Requires

ADVANTAGES

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1. High specific surface area and therefore

more heat transfer surface between particles and fluids.

2. Reduced pumping power as compared to

pure liquid to achieve equivalent heat transfer

intensification.

3. Reduced particle clogging as compared to

conventional slurries, thus promoting system

miniaturization.

4. Adjustable properties, including thermal

conductivity and surface wet ability, by varying

particle concentrations to suit different applications.

5. Heat transfer efficiency up to 45% in

comparison with pure water.

6. Overall heat transfer coefficient and heat

transfer rate in engine cooling system increased with

the usage of Nano fluids.

APPLICATION

Some of the main cooling applications by

using Nanofluids[2]

Space and defense

Heat transfer intensification Transportation

Electronic applications

Nuclear systems cooling

Industrial cooling

Conclusion

In this project Nanofluids are used as a

coolant in Radiators because it has a high thermal

conductivity due to its surface area compare to other

Coolants such as water and Ethylene Glycol.It has been

conclude that nanofluids have ability of high thermal

conductivity so it can be proposed to use in various

application. As heat transfer can be improved by

nanofluids, it reduce size and weight of the automobile

radiator, may results in increase the fuel economy.

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