DESIGN AND FABRICATION OF CIRCULAR DIMPLED RADIATORA PROJECT REPORTSubmitted by ARVIND KUMAR.G 711711114009 ATHI NARAYANAN.M 711711114010 CHRISTOPHER CHARLES 71171111401

DEEPAK.D 711711114012in partial fulfillment for the award of the degreeofBACHELOR OF ENGINEERINGIN

MECHANICAL ENGINEERINGKGiSL INSTITUTE OF TECHNOLOGYANNA UNIVERSITY::CHENNAI 600 025

APRIL 2014

ANNA UNIVERSITY : CHENNAI 600 025BONAFIDE CERTIFICATECertified that this project report ....DESIGN AND FABRICATION OF CIRCULAR DIMPLED RADIATOR..

is the bonafide work of ARVIND KUMAR.G 711711114009 ATHI NARAYANAN.M 711711114010 CHRISTOPHER CHARLES 71171111401

DEEPAK.D 711711114012who carried out the project work under my supervision.SIGNATUREMr. Venkataraman.,M.E (Ph.D)

HEAD OF THE DEPARTMENT (i/c)Associate Professor

Department of Mechanical Engineering

KGiSL INSTITUTE OF TECHNOLOGY COIMBATORE-641035

Internal ExaminerSIGNATUREJUDSON JOSHUARAJ B.E. MBA.,SUPERVISOR

Assistant Professor

Department of Mechanical Engineering

KGiSL INSTITUTE OF TECHNOLOGY COIMBATORE-641035

External Examiner

ACKNOWLEDGMENTWe express our deepest gratitude to our CHAIRMAN AND MANAGING DIRECTOR for providing us with an environment to complete our project successfully.

We are very grateful to our Dr.R.Ravichandran Ph.D.,Director and Dr.M.Rajendran., Ph.D., Principal for their valuable guidance and blessings.

We would like to thank Mr.K.Venkataraman.M.E (Ph.D) .,Head of the Dept(i/c) for his unwavering support during the entire course of this project first phase work and who modeled us both technically and morally for achieving greater success in this project work.

We express our sincere thanks to our guide Mr.Judson Joshuva raj B.E,MBA for his constant encouragement and support throughout our course, especially for the useful suggestions given during the course of the project period and being instrumental in the completion of our project with his complete guidance.

We also thank all the Non teaching staff members of our college for their help in making this project a successful one.

Finally, we take this opportunity to extend our deep appreciation to our family and friends, for all that they meant to us during the crucial times of the completion of our project.ABSTRACT Our Project FABRICATION OF CIRCULAR DIMPLE RADIATOR [Radiator as heat exchanger] mainly focuses on the thermal design and analysis of radiator as heat exchanger The project contains the design and material selection of the radiator for different type of vehicles also. For better efficiency, improvement of heat transfer rate is important phenomenon Radiators are heat exchangers used for cooling internal combustion engines mainly in

automobiles. The main objective of the project is to increase the heat transfer rate by modifying the rectangular shape radiator into circular shape radiator. The object of work is to have a circular radiator which is compact made with minimum. Material-less costly more efficient-that will work with minimum power consumption of fan and maximum utilization of air flow.

INDEX Acknowledgement

Abstract

Contents

List of figures

List of tables

List of symbols, abbreviations and Nomenclature

INTRODUCTION1.1 Introduction of heat exchanger The present manufacturing of heat exchangers commonly used in practice in Automobiles, Internal Combustion (IC) engines, Refrigeration systems, and Power plants emphasizes on production process, materials and spacing of fins. The heat transfer rate is increased from the fined surface to the surroundingflowing fluid by creating a dimpled surfaces and pinfins. Both the combinations of circular shape radiator and dimple surface on the pinfin which increases the heat transfer rate.

1.2 Types of heat exchanger and flow configurations

One of the simplest designs for a heat exchanger is the double pipe heat exchanger which is schematically illustrated in Fig. It consists of two concentric tubes, where fluid 1 flows through the inner pipe and fluid 2 flows in the annular space between the two tubes. Two different flow regimes are possible, either countercurrent where the two fluids flow in opposite directions, or concurrent as in Fig.

Figure1.1: Fluid temperatures 1 and 2 in a double-pipe heat exchanger. a countercurrent flow, b concurrent flowIn practical applications the shell-and-tube heat exchanger, as shown in Fig. is the most commonly used design. One of the fluids flows in the many parallel tubes which make up a tube bundle. The tube bundle is surrounded by a shell. The second fluid flows around the outside of the tubes within this shell. Countercurrent flow can be realized here except at the ends at of the heat exchanger where the shell side fluid enters or leaves the exchanger. The addition of baffles, as in Fig., forces the shell side fluid to flow perpendicular to the tube bundle, which leads to higher heat transfer coefficients than those found in flow along the tubes. In the sections between the baffles the fluid is neither in counter or concurrent flow but in cross flow.

Figure1.2: Shell-and-tube heat exchanger (schematic)These above all are main classification of the heat exchanger but these heat exchangers are also classified according to many ways some of them are shown as below.

2.1 Introduction of Radiators Radiators are heat exchangers used for cooling internal combustions, mainly in automobiles but also in piston engine aircraft, railway locomotives, motor cycles, stationary generating plantor any similar use of an engine. It is designed to transfer heat from the hot coolant that flows through it to the air blown through it by the fan .Mostly modern car use aluminium radiators.These radiators are made by brazing thin aluminium fins to flattened aluminium

tubes. The fins conduct the heat from the tubes and transfer it to the air flowing

through the radiator.

2.2 Auto Radiators and Car Parts Cooling System Glossary

Belt: Your cooling system uses an engine belt to drive the blower fan. Some cars have an additional electric motor to force air over the auto radiators cores.

Blower/Blower Motor: the fan assembly that pushes air across the cooling cores of your car radiator.

Coolant: The standard mix of anti-freeze and water used for cooling automobile engines.

Coolant Overflow Tank: When your car gets hot, the coolant expands and partially fills the coolant overflow tank. This is normal.

Fan: See Blower.

Heater Core: The opposite of the auto radiator's cooling core. It uses hot coolant coming from the engine to heat air for your car's heater.

Hoses: All car radiators use several hoses to pass the coolant to and from the engine. They are affixed to the auto radiator and engine with hose clamps.Oil Cooler: It is a secondary cooling system used in cars with automatic transmissions. It cools the oil from the automatic transmission.

Auto Radiators: The grid of specially shaped metal tubes behind the grill of your car. Hot coolant passes through these cores and is cooled by the air passing over them. This is the principal method of cooling an internal combustion engine and the car parts involved.

Radiator Cap: The pressure sensitive radiator cap on the top of your radiator. It increases the pressure in your cooling system, allowing more efficient cooling. The radiator cap is also designed to expel excess pressure caused from the coolant becoming too hot or boiling. This prevents damage to the cooling system.

Thermostat: This regulates the flow of coolant through the engine. It only opens when the engine gets hot enough, allowing your engine to heat up quickly (good in the winter!).

Transmission Oil Cooler: See Oil Cooler.

Water Pump: This pump forces the coolant through the cooling system.

Figure:2.1 Coolant path and Components of an Automobile Engine Cooling System2.3 FUNCTIONS OF RADIATOR A radiator is a type of heat exchangers.It is designed to transfer heat from the hot coolant that flows through to the air blow through it by the fan. The fin conduct the heat from the tubes and transfer it to the air flowing the radiator. The radiator cools the water that flows around the engine.it helps to cool liquids that exist in engine. Radiators also holds coolant to speed cooling process of liquids. Car radiators made by aluminium. Because aluminum does not rust.

2.4 CIRCULAR SHAPE RADIATOR

Normally radiators are in rectangular or in square in shape, therefore in this

case heat transfer rate does not takes place uniformly. In order improve the heat transfer rate in

car radiators the shape of a radiators are modified into circular shape. Due to this circular shape

uniform heat transfer rate takes place.

FIGURE: 2.2 Proposed Heat Exchanger (Radiator)

2.5 ADVANTAGES OF CIRCULAR SHAPE RADIATORS OVER RECTANGULAR SHAPE RADIATORS Compact in shape

Made with minimum material

Low cost

More efficient

Minimum power consumption

Maximum utilization of air flow

3.PIN FIN

3.1 Introduction of PIN FIN

Afinis a surface that extends from an object to increase the rate of heat transfer to or from the environment by increasingconvection. The amount ofconduction,convection, orradiation of an object determines the amount of heat it transfers. Increasing the temperaturedifference between the object and theenvironment, increasing the convectionheat transfer coefficient, or increasing the surface areaof the object increases the heat transfer. Sometimes it is not economicalor it is not feasible to change the first two options. Adding a fin to an object, however, increases the surface area and can sometimes be an economical solution to heat transfer problems. FIGURE 3.1 3.2 LONGITUDINAL FIN

Rectangular TrapezoidalTriangular Concave parabolicConvex parabolic3.3 FUNCTIONS OF FINS To increase the surface area of the metal body which provides cooling. It increases the efficiency to the maximum cooling effect To speed up the transfer of heat energy3.4 Dimpled surface pinfin

A tremendous amount of effort has been devoted to developing new methods to increase heat transfer from fined surface to the surrounding flowing fluid. Rib turbulators, an array of pin fins, and dimples have been employed for this purpose. There are two different types of dimples: 1) circular (spherical) dimples, and 2) oval (elliptical) dimples. Dimples were placed on both sides of a copper plate with a relative pitch of S/D=1.20 and relative depth of /D=0.2 (e.g., circular dimples). For oval dimples, similar ratios with the same total depth and circular-edge-to-edge distance as the circular dimples were used.

Fig.. Experimental Set-up

Fig.. Schematic drawings, (a) the entire test surface of the flat copper plate; (b) the entire test surface of the circular type copper plate with dimple dimensions ; (c) the entire test surface of the oval (elliptical) type copper plate with dimple dimensions. All dimensions are given in mm.

The dimpled surface on the pinfin will increase the heat transfer rate in the car radiators by

means of giving a high efficiency cooling effect.

CALCULATION4.1 INPUT:Mass flow rate through water jacket(kg/sec)(mc) = 0.35

Mass flow rate through air (kg/sec)(ma) = 10.66

Coolant temperature at radiator inlet (Tci) = 383k

Coolant temperature at radiator outlet (Tco) = 316k

Ambient inlet air temperature (Tai )= 298K

Specific capacity of air (cpa) = 1005J/Kgk

Specific capacity of coolant (Cpc) = 3621.582J/Kgk

4.2 Solution:

Mass flow rate through water jacket (mc)=1250Kg/hr =1250/3600

=0.35Kg/sec

Mass flow rate through air (ma) = PV/RT =1.013*10^5*9/287*298

=10.66 Kg/sec

Specific heat capacity of coolant (Cpc) = 0.865 (Btu/lbf)At equilibrium condition and assuming the cooling air accurate for all heat loss from the Radiator , it is to be expressed

Qa = QcQa=heat carried by the air from the radiator

Qa = macpa ( Ta0-Tai )

Qc = heat carried by the coolant radiator

Qc = mccpc ( Tci-Tco )Hence

Qa=Qc

Mccpc (Tci-Tc0) = macpa (Ta0-Tai)

7.927 = Ta0-298

Ta0=7.927+298

=305.927K

Where Ta0= outlet air temperature

4.3 ENGINE POWER INPUT

Qengine= 327.34KwHeat loss in engine:

Total quantity of heat converted in engine that is lost to cooling water

Qengine= mCPT

Qengine= Qradiator

Cooling surface heat transfer area (As) = Qradiator / hc (Tf-Ts)

Coolant side temperature (Ts) or Average wall surface temperature of radiator (k) = 310k

Mean fluid temperature between coolant inlet and outlet temperature (Tf) (k) = 363k

4.4 NUSSELT NUMBER

hc = 1.155 ( 1 + 1.24 Cm ) ( p2 T )^0.67

Cm = mean piston speed = 10 m/s

P = 1 atm

T = 365 K

T = Tavg hc = 803.20 w/m2 k

As = Qradiator / hc ( Tc Ts )

= 327.34*10^3 / 803.20 ( 363-310 )

As = 7.690 m2

/4 d2 = 7.690

d2 = 9.796

d = 3.130 m

4.5 FIN DETAILED CALCULATION: From various journals the following readings are taken: Fin area (A)

= 30*300.

Thermal conductivity of aluminium (K)

= 227 W/Mk. Surface temperature of fin (Ts)

= 373K.

Ambient temperature (T)

= 300K.

Convective heat transfer co-efficient for air (h)

= 20 W/M2k.

Thermal design power (Q)

= 327.34 KW.

FORMULA FROM HMT DATA BOOK:

Qfin = (hpkA)0.5(TB-T)tanh(ml).

Qwithout fin = hA (TB-T).

= tanh (ml)/ml.

Fin effectiveness (E) = Qfin/ Qwithout fin . Various fin calculation are shown below:

Space between two radiator tubes = 10mm.

Length of the fin = 10 mm.

Width of the fin = 30mm.

Thickness of the fin = 1mm .

Space between the two fins = 1mm.

Height of the radiator = 380mm.

Number of tube used = 30.

Number of fin = 185

One end of fins touched to tube To = 90oc.

One end of fin with ambient air Ta = 54oc.

Heat lost by fins Q = 1106.35 KW.

Fin efficiency = 94%.5. LIST OF FIGURES

S.NOFIGURE NO DESCRIPTIONPAGE NO.

1.1.1:Fluid temperatures 1 and 2 in a double-pipe heat exchanger

2. 1.2Shell-and-tube heat exchanger (schematic)

3. 2.1Coolant path and Components of an Automobile Engine Cooling System

4. 2.2Proposed Heat Exchanger (Radiator)

5.

6.

7.

8.

9.

10.

6. LIST OF SYMBOLS & NOMENCLATURE

S.NO SYMBOL USED PAGE NO

2.RADIATOR

1. INTRODUCTION AND LITERATURE REVIEW

vii

4. DESIGN CALCULATION