The Effect Of Hole Plate On Automotive Waste Heat Extraction.
APPROVAL OF SUPERVISOR
“I hearby declared that I have read through this report and I found that it has comply the partial fulfilment for awarding the degree in Bachelor of Mechanical Engineering
(Thermal Fluid)”
Signature : ………... Supervisor 1: Mr. Mohammad Firdaus B. Sukri Date : ...
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THE EFFECT OF HOLE PLATE ON AUTOMOTIVE WASTE HEAT EXTRACTION
MOHD NAWAWI BIN MUSTAFA
This dissertation is submitted as partial fulfillment of the requirement for the degree of Bachelor of Mechanical Engineering (Thermal Fluid)
Fakulty of Mechanical Engineering Universiti Teknikal Malaysia Melaka
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DECLARATION
“I declare that this report is done by my own exclude citation with the mentioned references for each.”
Signature :……….. Author : MOHD NAWAWI B. MUSTAFA Date :………..
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ACKNOWLEDGEMENT
First of all, I would like to give my appreciation to gratefulness, Allah SWT in order to complete my final project. This text could not have been written and produced without the help of many lecturer and colleagues. Appreciation is express to those who have viewed and made contributions so much in order to completion of the project, especially for Mr. Mohammad Firdaus b. Sukri for his idea, commitment, support, advised, time shared and guidance. Also a lot of appreciation and thankful to Mr. Nasir for his supervision during working on this project.
I would like to thankful to my parent Mr Zulkifly b. Abd Ghani and Mujiharti Bte. Hj. Abu Salim for their endless support and encourage to all of my work.
Lastly, special thank to my entire helpful friend for their support and useful information and idea.
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ABSTRACT
Exhaust system is one of the important parts in the engine system. Exhaust system causes huge impact on the performance of the engine. When vehicle start, exhaust system will warm up caused by combustion inside the cylinder. The exhaust gasses from the combustion will be issued through exhaust system. Sometimes the temperature of the exhaust system increase and at the same time the heat is dissipated to the environment air. According to Dr Harald Bottner the temperature difference between the exhaust pipe and a pipe carrying engine cooling fluid can thus be several hundred degrees Celsius. Therefore, the heat dissipated can be converted to electricity by using thermoelectric materials. In this project, the front pipe is modified by installing hole plate inside it. By using front pipe that has hole plate, it is predicted, that the wall temperature of this front pipe will rise up. Thus, much more heat can be dissipated and converted to electricity. The 1.3L Proton Satria engine is used and the result indicated that the new design of front pipe with hole plate can increase the wall temperature of the front pipe more than 200 degree Celsius. Furture step is by conceptual design and fabrication to make front pipe that have hole plate inside the front pipe to boost pipe wall temperatures of the front pipe. Painting by sketches and three dimensional designs must be carried out to make sure this project going well. The 3D design can be made using the software as Solidwork and Catia to make sure the design strong and no leakage problem before started the fabrication step. In the fabrication, welding, cutting and drilling will be used to make the front pipe. There were three design of front pipe that need to be made to find out the effect of hole plate at the exhaust system. The analysis will be carried out after finish the fabrication.
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ABSTRAK
Ekzos sistem adalah salah satu komponen yang penting dalam sesebuah enjin. Ekzos sistem memberi impak yang amat besar pada prestasi enjin kenderaan sama ada kereta mahupun motosikal. Apabila kenderaan dihidupkan sistem ekzos akan memanas disebabkan pembakaran di dalam enjin berkenaan. Pembakaran yang berlaku di dalam enjin akan dikeluarkan melalui sistem ekzos. Ada kalanya suhu sistem ekzos meningkat dan di masa yang sama haba terlepas ke persekitaran. Berdasarkan Dr. Harald Bottner (2004), perbezaan suhu di antara paip ekzos dan paip pembawa penyejukan enjin dijangkakan boleh melebihi ratusan darjah Celsius. Oleh itu, tenaga haba yang terhasil boleh diubah kepadatenaga elektrik menggunakan bahan thermoelektrik. Di dalam projek ini, paip hadapan diubahsuai dengan menambahkan kepingan besi berlubang di dalamnya. Dengan menggunakan rekabentuk yang terbaru, ia membayangkan bahawa suhu dinding paip hadapan akan meningkat. Oleh itu, lebih banyak tenaga haba akan dibebaskan dan diubah kepada tenaga elektrik. Enjin Proton Satria 1.3L digunakan di dalam kajian ini dan keputusan menunjukkan bahawa rekabentuk paip hadapan yang baru akan meningkatkan suhu dinding paip hadapan lebih daripada 200 darjah Celsius. Langkah seterusnya adalah dengan melukis dan membuat paip hadapan yang mempunyai kepingan besi berlubang didalamnye bagi meningkatkan suhu dinding paip hadapan. Lukisan secara lakaran dan tiga dimensi perlu bagi memastikan projek ini berjalan dengan lancar. Rekabentuk menggunakan perisian seperti Solidwork dan Catia perlu bagi membuktikan reka bentuk yang kukuh dan tiada sebarang masalah kebocoran pada paip hadapan. Proses pembuatan perlulah dijalankan bagi menghasilkan reka bentuk yang dikehendaki. Analisis daripada reka bentuk yang telah dihasilkan akan dijalankan apabila selesai proses pembuatan.
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CONTENTS
CHAPTER TITLE PAGE
ACKNOWLEDGEMENT iii
ABSTRACT v
ABSTRAK vi
CONTENT vii
LIST OF FIGURES x
CHAPTER 1 INTRODUCTION 1
1.1 Introduction 1
1.1.1 Overview of automotive
exhaust system 1 1.1.2 Overview of Electricity from
Exhaust Pipe 2
1.2 Problem Statement 4
1.3 Objective 4
1.4 Scopes 4
CHAPTER 2 LITERATURE REVIEW 5
2.1 Manifold of the exhaust system 5 2.2 Exhaust system installation 7 2.3 Heat transfer of the hole plate 7 2.5 Automobile exhaust system 8 2.5 Fourier’s Law of heat conduction 11 2.6 Conduction Heat Transfer 13
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CHAPTER TITLE PAGE
2.7 Convection Heat Transfer 14 2.8 Convection Energy Balance on a
Flow Channel 16
2.9 Heat Energy Converting to Electrical
Energy 17
CHAPTER 3 METHODOLOGY 19
3.1 Introduction 19
3.2 Flow charts 20
3.3 Conceptual sketching 21 3.3.1 Conceptual roughly sketching 21 3.4 Model design using Solidwork
software 21
3.4.1 Model 3 (Front pipe without
the hole plate) 22
3.4.2 Model 1 (Front pipe with 19 hole
and 7 plate in the same hole position) 24 3.4.3 Model 2 (Front pipe with 19 hole
and 7 plate at different hole position) 25
3.5 Fabrication and Manufacturing Process 26 3.5.1 Process of fabricating 26 3.5.2 Process of Cutting Cylinder Pipes 27 3.5.3 Process to merge all the part 28 3.6 Conduct Experiment in the
Automotive Laboratory 30 3.6.1 Conduct the laboratory testing
and analysis 32
3.7 Conduct the simulation of flow through the model using
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CHAPTER TITLE PAGE
CHAPTER 4 RESULT AND ANALYSIS 38
4.1 Introduction 38
4.2 Experiment 1: Determination
of location to place the model 39 4.3 Experiment 2: Determination the
effect of hole plate to the wall
temperature at the Model 1, 2 and 3. 41
4.3.1 Model 1 41
4.3.2 Model 2 47
4.3.3 Model 3 52
4.4 Simulation of Flow using
COSMOSFlow Work 56
CHAPTER 5 DISCUSSION 58
CHAPTER 6 CONCLUSION AND RECOMMENDATION 60
6.1 Conclusion 60
6.2 Recommendation and future work 61
REFERENCES 62
BIBLIOGRAFI 64
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LIST OF FIGURES
NO TITLE PAGE
1. Illustrated of Thermoelectric module 3
2. Exhaust manifold or header 5
3. Exhaust system used in automobile 8
4. Catalytic Converters 9
5. Exhaust manifold Gasket 9
6. Exhaust clamps 10
7. Exhaust flange 10
8. Headers 11
9. Thermal conductivity with different material
and different temperature 13
10. Convection heat transfer from plate 14 11. Approximate values of convection
heat-transfer coefficients 15
12. Convection in a channel 16
13. Thermoelectric generators convert heat directly
into electric energy 17
14. Position where the front pipe to be placed 22 15. 3D design of front pipe without hole plate 23
16. Orthographic drawing 23
17. Front pipe with same position of hole plate 24 18. 3D design using Solidwork software 24 19. 3D design using Solidwork software 25
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NO TITLE PAGE
20. Front pipe with different hole position 25
21. The hole plate for the model 26
22. The cylinder pipes after cutting process 27 23. Flange or bracket after Laser Cutting process 28 24. Model of hole plate from left Model 2,
Model 1 and Model 3 29
25. Proton Satria will be hanging to measure the
temperature of exhaust system 30 26. The meter speed to maintain the fuel pedal 31 27. The model of hole plate at the Proton Satria
exhaust system 33
28. Illustrated of placing the Thermocouple at
the model 33
29. Position to be placed after the catalytic converter 35 30. The flow of gas when go through the sample
model from Solidworks Corporation 37
31. Graph of Temperature vs Speed 39
32. Exhaust system for Proton Satria Hatchback 40 33. Conduction through the pipe wall 43 34. Boundary layer of convection heat-transfer 44 35. Graph of Temperature vs. Speed for Model 1 44 36. Graph of Heat-Transfer Energy, Qwallvs.
Speed (rpm) for Model 1 45
37. Model 1 46
38. Graph Temperature vs. Speed for Model 2 50 39. Graph of Heat-Transfer Energy (kW) vs. Speed (rpm) 50
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NO TITLE PAGE
40. Model 2 51
41. Graph of Temperature vs. Speed 55
42. Graph of Heat-Transfer Energy (kW) vs. Speed (rpm) 55 43. The flow of the gases when pass the inlet of the
Model 1 56
44. The flow of the gases when pass the inlet of Model 2 56 45. The flow of the gases when pass the inlet of Model 3 57
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LIST OF TABLE
NO TITLE PAGE
1.1 Temperature reading of exhaust system at motorcar 32 2.1 Temperature Gain at model 1 or 2 or 3 36 3.1 Temperature reading of exhaust system at motorcar
(PROTON SATRIA) 39
4.1 Temperature gain at Model 1 41
5.1 Temperature gain at Model 2 47
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CHAPTER 1
INTRODUCTION
The purpose of this chapter is to provide overview information on automotive exhaust system, heat transfer during experiment and the objective of the project and scope that will be conducted in this thesis. The overview of automotive waste heat extraction also will be explained in this chapter. Mainly this chapter will briefly explain about what will be discuss on other chapter.
1.1 Overview of Automotive Exhaust System
An exhaust system based on Tsuruta Yuuichirou (2004), is used to guide the waste gases away from combustion inside the engine. The system conveys burnt gases from the engine and includes one or more exhaust pipes. Depending on the overall exhaust system, the exhaust gas may flow through one or more of:
Cylinder head and exhaust manifold. A turbocharger to increase engine power. A catalytic converter to reduce air pollution. A muffler or silencer to reduce noise.
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In most production engines, the manifold is an assembly designed to collect the exhaust gas from two or more cylinders into one pipe. These design restrictions often result in a design that is cost effective but that does not do the most efficient job of venting the gases from the engine. Since cylinders fire at different times, exhaust leaves them at different times, and pressure waves from the gas emerging from one cylinder exactly might not be completely vacated through the exhaust system when another comes.
This creates a back pressure and restriction in the engine's exhaust system that can restrict the engine's true performance possibilities. The high pressure and high temperature that arrived through the pipe easily can be absorbed to change the energy to energy. From that, the energy goes out from the combustion inside the engine can perform a better energy and restore the energy for using to make another work.
1.2 Overview of Electricity from Exhaust Pipe
In an age of dwindling natural resources, energy savings is the order of the day. However, technical processes use less than one-third of the energy they employ. This is particularly true of automobiles, where two-thirds of the fuel remains unused in the form of heat. About 30% is lost through the engine block and a further 30 to 35% as exhaust fumes. Dr Harald Bottner (2004) stated that the temperatures in the exhaust pipe can reach 700 degrees Celsius or more. The heat energy from the exhaust system then converts the heat energy to the electrical energy using thermoelectric generators (TEGs). These devices convert heat into electrical energy by making use of a temperature gradient. The greater the temperature difference, the more current TEGs can produce. The temperature difference between the exhaust pipe and a pipe carrying engine cooling fluid can thus be several hundred degrees Celsius.
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Researchers at the Fraunhofer Institute for Physical Measurement Techniques IPM in Erlangen, Germany, are developing thermoelectric materials, modules and systems to harness the residual heat in automobiles.
Figure 1: Illustrated of Thermoelectric module (Source: Thomas Johann Seebeck, (1821))
The thermoelectric converter makes use of this huge differential and driven by the flow of heat between the hot exhaust fumes and the cold side of a coolant pipe. The charge carriers pass through special semiconductors, thus producing an electric current similar to a battery. According to Jihui Yang (2008), the thermoelectric generator works when one side of its metallic material is heated, and excited electrons move to the cold side. The movement creates a current, which electrodes collect and convert to electricity. Dr Harald Bottner (2004) stated that TEGs could cover a significant proportion of a car’s power requirements and it possible to cut gas consumption by between 5 and 7%.
Dr Harald Bottner (2004), stated that there are about 50 million licensed motor vehicles in Germany, each of which is on the road for an average of 200 hours a year. If their waste heat were utilized by TEGs during that time, with an output of one kilowatt sufficient to power parts of vehicle electronics, this would add up to ten terawatt hours of energy per annum. The researchers are still in the experimentation phase at present, but they plan to build the first prototypes very soon.
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1.3 Problem statement
The study of effect of hole plate on the automotive waste heat extraction. In this project, the effect of the gasses flow through the hole plate will be discovered whether the temperature increasing or decreasing at the exhaust system. The performance of the engine and the temperature different at the exhaust system will be discovered. The flow of the exhaust combustion through the model will be showed using COSMOSFlowwork software.
1.4 Research Objective
The objective of this project is to increase the wall temperature of front pipe by using hole plate for automotive waste heat recovery.
1.5 Scope of the Project
I. Conduct literature review on automotive exhaust systems and heat transfer.
II. Conceptual design using software Solidwork of the front pipe of hole plate.
III. Fabrication of the front pipe.
IV. Perform experiment to investigate the effect of hole plate on the model.
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CHAPTER 2
LITERATURE REVIEW
2.1 Manifold or Header of the Automotive Exhaust System
In most production engines, the manifold is an assembly designed to collect the exhaust gas from two or more cylinders into one pipe. Manifolds are often made of cast iron in stock production cars, and may have material-saving design features such as to use the least metal, to occupy the least space necessary, or have the lowest production cost. These design restrictions often result in a design that is cost effective but that does not do the most efficient job of venting the gases from the engine. Inefficiencies generally occur due to the nature of the combustion engine and its cylinders.
Since cylinders fire at different times, exhaust leaves them at different times, and pressure waves from gas emerging from one cylinder might not be completely vacated through the exhaust system when another comes. This creates a back pressure and restriction in the engine's exhaust system that can restrict the engine's true performance possibilities.
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A header (sometimes called extractor in Australia) is a manifold specifically designed for performance. During design, engineers create a manifold without regard to weight or cost but instead for optimal flow of the exhaust gases. This design results in a header that is more efficient at scavenging the exhaust from the cylinders. Headers are generally circular steel tubing with bends and folds calculated to make the paths from each cylinder's exhaust port to the common outlet all equal length, and joined at narrow angles to encourage pressure waves to flow through the outlet, and not back towards other cylinders. In a set of tuned headers the pipe lengths are carefully calculated to enhance exhaust flow in a particular engine revolutions per minute range (Source: www.Wikipedia, October (2007)).
Headers are generally made by aftermarket automotive companies, but sometimes can be bought from the high-performance parts department at car dealerships. Generally, most car performance enthusiasts buy aftermarket headers made by companies solely focused on producing reliable, cost-effective well-designed headers specifically for their car.
Headers can also be custom designed by a custom shop. Due to the advanced materials that some aftermarket headers are made of, this can be expensive. Luckily, an exhaust system can be custom built for any car, and generally is not specific to the car's motor or design except for needing to properly connect solidly to the engine. This is usually accomplished by correct sizing in the design stage, and selecting a proper gasket type and size for the engine (Source: www.Wikipedia, October (2007)).
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2.2 Exhaust System Installation
According to Christopher Shortt and Elizabeth Hough (2004), the exhaust systems are designed for the vehicle they are in and the engine that is in the vehicle. In-line engines have a simple design that runs down one side of the engine. Called a single exhaust system, there is only one pipe to the rear of the car.
Single exhausts can be found on all engine sizes. A single exhaust system has one path for exhaust flow through the system. Typically, it has only one header pipe, a main catalytic converter, a muffler, and a tailpipe. This is the most common type of exhaust system.
V-type engines with dual exhaust have two pipes, two mufflers, and two catalytic converters. A dual exhaust allows better breathing when the engine is under load. A dual exhaust system has two separate exhaust paths to reduce the back pressure. A crossover pipe joins the two manifolds into one pipe as they leave the engine on a V-type engine’s single exhaust system. A crossover pipe normally connects the right and left header pipes to equalize back pressure in a dual system. This also increases engine power slightly.
Through most cars and light trucks have exhaust systems with only a single catalytic converter, there are some with dual converters or piggyback converters. Service and repair procedures are pretty much the same on the dual-converter systems as those with only a single converter.
2.3 Heat Transfer of the Hole Plate
In the simplest of terms, the discipline of heat transfer is concerned with only two things such as temperature and the flow of heat. Temperature represents the amount of thermal energy available, whereas heat flow represents the movement of thermal energy from place to place. According to Richard Hedrick (2005), on a microscopic scale, thermal energy is related to the kinetic energy of molecules.
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The greater a material's temperature, the greater the thermal agitation of its constituent molecules (manifested both in linear motion and vibration modes). It is natural for regions containing greater molecular kinetic energy to pass this energy to regions with less kinetic energy. In thermal physics, heat transfer is the passage of thermal energy from a hot to a colder body. When a physical body, e.g. an object or fluid, is at a different temperature than its surroundings or another body, transfer of thermal energy, also known as heat transfer, or heat exchange, occurs in such a way that the body and the surroundings reach thermal equilibrium. Heat transfer always occurs from a hot body to a cold one, a result of the second law of thermodynamics. Where there is a temperature difference between objects in proximity, heat transfer between them can never be stopped; it can only be slowed down (Source: www.wikipedia.org).
2.4 Automobile Exhaust System
According to Ryznic and John (1997), an automobile exhaust system comprises of various devices or parts of an automotive engine, which are used for discharging burned gases or steam. Exhaust systems consists of tubing, which are usually used for emitting out waste exhaust gases with the help of a controlled combustion taking place inside an automobile engine. All the burnt gases are exhaled from an engine using one or more exhaust pipes. These gases are expelled out through several devices like cylinder head, exhaust manifold, turbocharger, catalytic converter, muffler and silencer.
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According to (Usui et al, (1985)), the major components used in a typical automobile exhaust system are exhaust manifold, resonator, catalytic converter, exhaust pipe, muffler, tail pipe, ‘Y’ pipe, ball flanges. All of these components are especially designed for providing suitable and effective exhaust flow, silencing, and emission levels. Exhaust Pipes are explicitly engineered to carry or transmit various toxic and noxious gases away from the users of the machine. Usually, exhaust gases are very hot, that is why exhaust pipes must be durable and heat resistant so that it does not get spoiled by heat. These double walled pipes are manufactured using different types of metals namely aluminized steel, stainless steel or zinc plated heavy-gauge steel. The exhaust pipes joins exhaust manifold, muffler and catalytic converters together.
Figure 4: Catalytic Converters (Source: John, (1997))
Catalytic Converters are the devices used for converting toxic and harmful hydrocarbons, carbon monoxide, and nitrogen oxides into harmless compounds. Converters transform hydrocarbons and carbon monoxide into carbon dioxide and water while separate nitrogen oxide into nitrogen and oxygen respectively. Catalytic converter is positioned underneath the passenger seat in most of the vehicles. The converter make use of various catalysts like platinum, palladium, and rhodium coated on a ceramic honeycomb structure which turns the dangerous gases into non toxic gases.
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Exhaust Manifold Gaskets consists of strong network of pipes that are used for collecting gases from cylinders and passes them directly to the exhaust pipe. Manifold gaskets are mostly made of cast or nodular iron, embossed steel, high temperature fiber material, graphite and other ceramic composites. The main function of exhaust manifold gasket is to seal the connection between the manifold and cylinder head. The design of exhaust gasket usually depends on the type of engine used and number of cylinders it has. It helps to prevent the leakage and allows exhaust gas to flow through catalytic converter easily and comfortably.
Figure 6: Exhaust clamps (Source: John, (1997))
Exhaust clamps are the components used for providing a strong connection between various pipe sections and other engine components. Mostly, steel is used for manufacturing exhaust clamps. It comes in wide array of sizes and can accommodate different sizes of exhaust pipes and connections. Exhaust brackets are a type of fastener generally made of steel and is used for providing support to different components used in an automobile exhaust system.
Figure 7: Exhaust flange (Source: John, (1997))
Exhaust Flange is a type of projecting rim used for attaching, joining or fastening tightly various exhaust pipes with the help of nuts and bolts. These flanges are mostly made of stainless steel, iron, aluminum, steel, carbon steel, alloy steel, and hardened steel.
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CHAPTER 2
LITERATURE REVIEW
2.1 Manifold or Header of the Automotive Exhaust System
In most production engines, the manifold is an assembly designed to collect the exhaust gas from two or more cylinders into one pipe. Manifolds are often made of cast iron in stock production cars, and may have material-saving design features such as to use the least metal, to occupy the least space necessary, or have the lowest production cost. These design restrictions often result in a design that is cost effective but that does not do the most efficient job of venting the gases from the engine. Inefficiencies generally occur due to the nature of the combustion engine and its cylinders.
Since cylinders fire at different times, exhaust leaves them at different times, and pressure waves from gas emerging from one cylinder might not be completely vacated through the exhaust system when another comes. This creates a back pressure and restriction in the engine's exhaust system that can restrict the engine's true performance possibilities.
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A header (sometimes called extractor in Australia) is a manifold specifically designed for performance. During design, engineers create a manifold without regard to weight or cost but instead for optimal flow of the exhaust gases. This design results in a header that is more efficient at scavenging the exhaust from the cylinders. Headers are generally circular steel tubing with bends and folds calculated to make the paths from each cylinder's exhaust port to the common outlet all equal length, and joined at narrow angles to encourage pressure waves to flow through the outlet, and not back towards other cylinders. In a set of tuned headers the pipe lengths are carefully calculated to enhance exhaust flow in a particular engine revolutions per minute range (Source: www.Wikipedia, October (2007)).
Headers are generally made by aftermarket automotive companies, but sometimes can be bought from the high-performance parts department at car dealerships. Generally, most car performance enthusiasts buy aftermarket headers made by companies solely focused on producing reliable, cost-effective well-designed headers specifically for their car.
Headers can also be custom designed by a custom shop. Due to the advanced materials that some aftermarket headers are made of, this can be expensive. Luckily, an exhaust system can be custom built for any car, and generally is not specific to the car's motor or design except for needing to properly connect solidly to the engine. This is usually accomplished by correct sizing in the design stage, and selecting a proper gasket type and size for the engine (Source: www.Wikipedia, October (2007)).
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2.2 Exhaust System Installation
According to Christopher Shortt and Elizabeth Hough (2004), the exhaust systems are designed for the vehicle they are in and the engine that is in the vehicle. In-line engines have a simple design that runs down one side of the engine. Called a single exhaust system, there is only one pipe to the rear of the car.
Single exhausts can be found on all engine sizes. A single exhaust system has one path for exhaust flow through the system. Typically, it has only one header pipe, a main catalytic converter, a muffler, and a tailpipe. This is the most common type of exhaust system.
V-type engines with dual exhaust have two pipes, two mufflers, and two catalytic converters. A dual exhaust allows better breathing when the engine is under load. A dual exhaust system has two separate exhaust paths to reduce the back pressure. A crossover pipe joins the two manifolds into one pipe as they leave the engine on a V-type engine’s single exhaust system. A crossover pipe normally connects the right and left header pipes to equalize back pressure in a dual system. This also increases engine power slightly.
Through most cars and light trucks have exhaust systems with only a single catalytic converter, there are some with dual converters or piggyback converters. Service and repair procedures are pretty much the same on the dual-converter systems as those with only a single converter.
2.3 Heat Transfer of the Hole Plate
In the simplest of terms, the discipline of heat transfer is concerned with only two things such as temperature and the flow of heat. Temperature represents the amount of thermal energy available, whereas heat flow represents the movement of thermal energy from place to place. According to Richard Hedrick (2005), on a microscopic scale, thermal energy is related to the kinetic energy of molecules.
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The greater a material's temperature, the greater the thermal agitation of its constituent molecules (manifested both in linear motion and vibration modes). It is natural for regions containing greater molecular kinetic energy to pass this energy to regions with less kinetic energy. In thermal physics, heat transfer is the passage of thermal energy from a hot to a colder body. When a physical body, e.g. an object or fluid, is at a different temperature than its surroundings or another body, transfer of thermal energy, also known as heat transfer, or heat exchange, occurs in such a way that the body and the surroundings reach thermal equilibrium. Heat transfer always occurs from a hot body to a cold one, a result of the second law of thermodynamics. Where there is a temperature difference between objects in proximity, heat transfer between them can never be stopped; it can only be slowed down (Source: www.wikipedia.org).
2.4 Automobile Exhaust System
According to Ryznic and John (1997), an automobile exhaust system comprises of various devices or parts of an automotive engine, which are used for discharging burned gases or steam. Exhaust systems consists of tubing, which are usually used for emitting out waste exhaust gases with the help of a controlled combustion taking place inside an automobile engine. All the burnt gases are exhaled from an engine using one or more exhaust pipes. These gases are expelled out through several devices like cylinder head, exhaust manifold, turbocharger, catalytic converter, muffler and silencer.
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According to (Usui et al, (1985)), the major components used in a typical automobile exhaust system are exhaust manifold, resonator, catalytic converter, exhaust pipe, muffler, tail pipe, ‘Y’ pipe, ball flanges. All of these components are especially designed for providing suitable and effective exhaust flow, silencing, and emission levels. Exhaust Pipes are explicitly engineered to carry or transmit various toxic and noxious gases away from the users of the machine. Usually, exhaust gases are very hot, that is why exhaust pipes must be durable and heat resistant so that it does not get spoiled by heat. These double walled pipes are manufactured using different types of metals namely aluminized steel, stainless steel or zinc plated heavy-gauge steel. The exhaust pipes joins exhaust manifold, muffler and catalytic converters together.
Figure 4: Catalytic Converters (Source: John, (1997))
Catalytic Converters are the devices used for converting toxic and harmful hydrocarbons, carbon monoxide, and nitrogen oxides into harmless compounds. Converters transform hydrocarbons and carbon monoxide into carbon dioxide and water while separate nitrogen oxide into nitrogen and oxygen respectively. Catalytic converter is positioned underneath the passenger seat in most of the vehicles. The converter make use of various catalysts like platinum, palladium, and rhodium coated on a ceramic honeycomb structure which turns the dangerous gases into non toxic gases.
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Exhaust Manifold Gaskets consists of strong network of pipes that are used for collecting gases from cylinders and passes them directly to the exhaust pipe. Manifold gaskets are mostly made of cast or nodular iron, embossed steel, high temperature fiber material, graphite and other ceramic composites. The main function of exhaust manifold gasket is to seal the connection between the manifold and cylinder head. The design of exhaust gasket usually depends on the type of engine used and number of cylinders it has. It helps to prevent the leakage and allows exhaust gas to flow through catalytic converter easily and comfortably.
Figure 6: Exhaust clamps (Source: John, (1997))
Exhaust clamps are the components used for providing a strong connection between various pipe sections and other engine components. Mostly, steel is used for manufacturing exhaust clamps. It comes in wide array of sizes and can accommodate different sizes of exhaust pipes and connections. Exhaust brackets are a type of fastener generally made of steel and is used for providing support to different components used in an automobile exhaust system.
Figure 7: Exhaust flange (Source: John, (1997))
Exhaust Flange is a type of projecting rim used for attaching, joining or fastening tightly various exhaust pipes with the help of nuts and bolts. These flanges are mostly made of stainless steel, iron, aluminum, steel, carbon steel, alloy steel, and hardened steel.