NB. This is a draft and is not complete.
CHAPTER 1: INTRODUCTION
1.1 INTRODUCTION AND PROBLEM SUMMERY
Today, the world is facing from various types of pollution due to which environment is harmed and people is facing from various types of disease. Apart from various types of pollution one of them is an air pollution which is caused due to burning of fossil fuels, agricultural activities, exhaust from factories and industries and mining operation etc. Rather than other causes the major one is burning of fossil fuel. Fossil fuel like petrol, diesel, coal and natural gas causing air pollution by emitting sulphur dioxide. Carbon monoxide is released from automobile vehicle like trucks, cars, motorcycle, rickshaw and bus etc. occurs due to incomplete combustion of fossil fuel i.e. petrol and diesel. We depend on fossil fuels to fulfil our daily basic need of transportation. But its overuse is killing our environment as dangerous gases polluting an environment. Along with these due to rapid increase in population of the world, demand of fossil fuel increases results in shortage of fossil fuel and price rise. As to protect our environment and to find alternate fuel for near future one of the alternate fuel is compressed air. Compressed air is used in place of fossil fuel. As, we know that air is freely available in nature and it is eco-friendly. We can use compressed air as a fuel in automobile vehicles rather than burning petrol or diesel inside the engine cylinder, as the exhaust coming from compressed air engine doesn’t harm the environment. By running the vehicle by a renewable energy like compressed air saves lots of money of people as well as saves the environment.
Depletion of these fuels has led researchers to anticipate the need to search the alternative way to drive the vehicles. Present work utilizes the air as a alternative of petrol or diesel. As we know that air is non-polluting and freely available in nature. The utilization of this freely available air is the good idea for automobile sector. Compressed air technology attracts the researchers and several industries world widely. Compressed air engine operates with the compressed air and is very simple in construction and operation. Here, compressed air from the air cylinder pushes the piston giving the power stroke. In the next stroke piston escape the expanded air from the cylinder. Thus, the cycle is completed in two strokes. Therefore, uniform turning effort is obtained unlike four stroke engine.
Fuel tank and spark plug is eliminated from the conventional four stroke engine. In the case of a compressed air Engine, there is no combustion taking place within the engine. So, it is less dangerous and non-polluting. It requires lighter metal only since it does not have to withstand elevated temperatures. As there is no combustion taking place and carburetor is eliminated because carburetor is used for mixing of fuel and air purpose. There is no need for mixing fuel and air, here compressed air is the fuel and it is directly fed into the piston cylinder arrangement. It simply expands inside the cylinder and does useful work on the piston. This work done on the piston provides sufficient power to the crankshaft.
1.1. OBJECTIVE OF THE PROJECT
The primary objective of our project is to develop an engine which uses compressed air as a fuel instead of fossil fuel. By doing so, it will probably sort out the matter of fuel crisis which our generation are facing. And to stop reckless use of fossil fuel as well as to avoid its harmful effect.
1.2. PROBLEM SPECIFICATION
Although, there are many types of engines are available to get transformed into compressed air engine but we choose only two amongst them, the 2-stroke engine and 4-stroke engine. We did not go after the rest because of many factors like their availability, cost, design, valve timing assemblies.
First, we select 2-stroke engine for our project to get converted into compressed air engine. But, we cannot stick on it due to its certain limitations. In this considered design there is a hurdle which makes it difficult to work on compressed air. In order to run 2-stroke engine we have to a mean effective pressure on the piston. But, by doing so the intake and power stroke gets overlap. Also, the exhaust stroke was rather difficult as there is no fuel to push out the exhaust gases out of the cylinder. Apart from this, lubrication factor also affecting the moving parts of an engine. As we already know that in 2-stroke engine only engine oil is not enough for lubrication of internally moving parts. It requires pre-mixing of petrol and engine oil for lubricating internally moving parts of an engine. Also, the crankcase of a 2-stroke engine is being used to pump fuel air mixture into the engine cylinder. All this factor may damage internal parts of an engine. So, we decided to reject the 2-stroke engine.
Then, we go after 4- stroke engine. After doing certain analysis we concluded that this engine can be converted into compressed air engine as the power stroke and intake stroke can be combined together and also, we can pump the compressed air in, directly on piston head which is full of flat surface in this case. Also, this engine easily available and economic. Apart from this we get rid of the factors like overlapping and lubrication issue which happens in case of 2-stroke engine. After selecting 4-stroke engine for our project, we need to select a particular 4-stroke engine.
CHAPTER 2: LITERATURE REVIEW
A literature review for the present work was carried out. Various research paper web articles were studied relevant to the topic of work.
Swadhin Patnaik[1]“Compressed Air Engine’’. This paper work deals with the Compressed-air engine as a pneumatic actuator that converts one form of energy into another. An Air Driven Engine is a pneumatic actuator that creates useful work by expanding compressed air. If we compress normal air into a cylinder the air would hold some energy within it. This energy can be utilized for useful purposes.
JP Yadav and Bharat Raj Singh[2]“Study and Fabrication of Compressed Air Engine’’
This paper shows the experimental analysis were carried out on this modified engine to find out its performance characteristics like brake power, mechanical efficiency, overall efficiency, air to Air ratio, volumetric efficiency, cost analysis etc. Though the efficiencies were low as the frictional forces were high for the proto designed engine, however the concept can be applied on a professionally designed engine to improve its performance.
Franco Antony, P J Albert, Rimin P R , Rino Disney, Sooraj M S , Sreevalsan S Menon[3]“Design and Development of Pneumatic Hybrid Vehicle (PHV)’’ In this paper they represent pneumatic hybrid vehicle in which the vehicle is being powered up by an internal combustion engine and an air engine; output is being taken up as desired. The air hybrid engine absorbs a part of vehicle’s kinetic energy, stores it in an air tank in the form of compressed air, and reuses it to propel a vehicle during cruising and acceleration. Capturing, storing and reusing the energy to give additional power can therefore improve fuel economy, particularly in cities and urban areas where the traffic conditions involve many stop sand starts.
Mistry Manish K, Dr.PravinP.Rathod, Prof.Sorathiya Arvind S[4]“Study And Development Of Compressed Air Engine Single Cylinder’’ This paper is reports on the review of compressed air engine for the design and development of single cylinder engine which can be run by the compressed air. Current four strokes single cylinder engine (bikes/moped) can be run on the compressed air with a few modifications that are the main objective of the study. Compressed air filled by electricity using a compressor. The electricity requirement for compressing air has to be considered while computing overall efficiency.
Brett A. Musselman And Curtis G. Kuder[5]“Vehicle mounted compressed air distribution system’’A pressurized gas system controls a gas flow from one or more gas pressure storage vessels by means of an electronically controlled electro-mechanical shut-off valve located in close proximity to each of the vessels. The shut-off valves are electrically wired to actuation switches on the control panel. Pressure transducers mounted on each vessel provide a signal output which is electrically connected to a digital numeric display located on the control panel so that the pressure of each vessel can be monitored. Gas flow from the vessels is controlled by means of the electric shut-off valves operated from the control panel. A pressure regulator at the air access station controls the final output pressure delivered to the tool or personnel air bottle.
Cheol-seung Cho And Kwang-soo Han[6]“Engine Using Compressed Air’’An engine driven by compressed air, including an electric motor driven by a battery , a compressor for generating the compressed air by use of a drive power of the electric motor , an intake manifold connected with an outlet of the compressor with the intake manifold , a crank shaft having four separate crank pins being connected to a piston in the cylinder by a connecting rod, and a cam shaft connected with the crank shaft by a belt or chain.
John R. Murphy[7]“Compressed air operated motor employing dual lobe cams’’An air-operated engine system usable for driving a vehicle by means of compressed air from a rechargeable storage tank. The engine of the system has cylinders containing driving pistons connected to a crankshaft. Compressed air from the storage tank is supplied at regulated pressure to the cylinders for power strokes by means of intake valves and the air is exhausted from the cylinders at the ends of the power strokes by means of exhaust valves. The intake and exhaust valves are operated by dual lobe cams on a camshaft driven from the crankshaft.
CHAPTER 3: METHODOLOGY
3.1. WORKING OF FOUR STROKE SI ENGINE
A cycle is a sequence of operations constantly repeated, and ‘four-stroke’ refers to the number of strokes of the piston required to complete one cycle. Refer Fig. 3.1. for the arrangement of different parts of four stroke cycle system. The reciprocating piston is present inside a cylinder, which is connected to the crankshaft through connecting rod and the crank. The inlet (suction) and outlet (exhaust) valves are housed in the cylinder head. The cylinder is also provided with an electric spark plug. The important parts of the engine are the connecting rod, piston, crankshaft and the cylinder block which including the cylinder head. The cylinder head comprises of the rocker arm and spring mechanism. Cam controls the opening and closing of the inlet valve and exhaust valve. The cylinder block is surrounded by cooling water jackets to cool the engine block.
In Four stroke – cycle engine, the cycle of operation is completed in four-strokes of the piston or can say in two revolutions of crankshaft. It means 720 degrees (Crank angle) for complete cycle.Fig. 3.1., showing the position and movement of piston.
Fig 3.1. Components of 4 stroke S.I. engine
I. Intake Camshaft R. Connecting rod
E. Exhaust Camshaft C. Crankshaft
S. Spark Plug V. Valves
P. Piston W. Water jacket
3.1. Components of 4-Stroke SI Engine
The four strokes of SI engine are as follow:
1. Suction
2. Compression stroke
3. Expansion stroke
4. Exhaust stroke
Fig.3.1.1. Top Dead Centre, Before Cycle Begins
Intake stroke:
The Intake Stroke is also known as Suction or Induction stroke. This stroke begins at T.D.C. (Top Dead Center) and ends at B.D.C. (Bottom Dead Center). The Intake valve must be in open position during the stroke while piston pulls an air-fuel mixture into the cylinder by creating vacuum pressure into the cylinder by moving in downward direction.
Fig.3.1.2. Intake Stroke
Compression stroke:
The second stroke is the compression stroke in which the piston moves from BDC to TDC. This stroke begins at the end of intake stroke. During this stroke both the inlet and exhaust valve are closed. Piston travels from B.D.C. to T.D.C. and compresses an air-fuel mixture into the cylinder.
Fig.3.1.3. Compression stroke
Expansion stroke:
This stroke is also known as power stroke, ignition Stroke or combustion Stroke. During this stroke both the valves remain closed. A crankshaft has already completed its one revolution. Currently, a piston is at T.D.C. the compressed air-fuel mixture is ignited by the spark plug which pushes the piston towards B.D.C.
Fig.3.1.4. Fuel Ignites
Fig.3.1.5. Power Stroke
Exhaust stroke:
This stroke is also known as outlet stroke. Commencement of this stroke begins at B.D.C. and ends at T.D.C. During which the exhaust valve opens and inlet valve are closed. The piston travels towards T.D.C. and pushes all exhaust gases through the exhaust valve.
Fig.3.1.5. Exhaust Stroke
3.2. BASIC FUNCTION OF C.A.E.
In C.A.E. there will be only two working strokes. Compressed air is supplied to the engine which will push the piston in downward direction hence giving piston a power to drive the engine. But as the piston comes up, the exhaust valve should be to open, so that the compressed air should get outside. Now to minimize forces on the piston head the intake valve will also have to be closed while piston is coming up.
3.3. WORKING OF COMPRESSED AIR ENGINE
As the engine is supplied with the compressed air so compression stroke will not be required because when the compressed air will again be compressed the power output would not be sufficient. So, the remaining strokes that we are left with are 3. If we study these remaining strokes, then it is obvious that the intake stroke and the power stroke are same which leaves us with two strokes only. Now it is required to convert the selected 4-stroke engine to 2-strokeengine. Before going any further let us define these two strokes which will act in the compressed air engine.
Stroke 1:
In this stroke, the intake valve will open and exhaust valve is closed. The commencement of stroke is from top dead center and ends at bottom dead center.
Fig.3.3.1 Intake Stroke
Now the compressed air will make impact on the piston. As a result, the piston will travel from the top dead centre to the bottom dead centre. Hence this stroke itself acts as power stroke as well. Therefore, there will be no need of extra power stroke.
Stroke 2:
In this stroke inlet or intake valve are closed and exhaust valve opens. The piston once again travel towards top dead centre from bottom dead center and compressed air are pushed out from the cylinder into the atmosphere due to the upward movement of piston through exhaust valve.
Fig.3.3.2 Exhaust Stroke
3.4. VALVE TIMING
The Compressed Air Engine consists of two stroke in order to achieve these strokes it is necessary to change the valve timing of an engine. The timing of the engine should be adjusted in such way that the inlet and exhaust valve opens once during every one revolution of crankshaft. In other words, it can be said that both the valves open twice during two revolution of crankshaft. Valve timing of an engine can be achieved by changing the design of camshaft.
3.5. MODIFICATION OF CAMSHAFT
Camshaft is the mechanical part of the engine. Camshaft controlling the movements of valves and if the profile of the camshaft will be changed then the valve moment is changed as well. Fig. 3.5.1 shows the camshaft of a 4-stroke S.I. engine.
3.5.1. Camshaft of a 4-Stroke S.I. engine
Currently, a camshaft profile is such that it can open inlet and exhaust valve once during two revolution of a crankshaft. But we need to open both the valves twice for two revolution of crankshaft it can only be possible by employing two more lobs at 180 degree. Fig. 3.5.2. shows the modified camshaft of a 4-stroke S.I. engine.
3.5.2. Modified Camshaft of 4-Stroke S.I. engine
Camshaft shown in fig. 3.5.2 will be employed in a compressed air engine. It will open the valve twice during 720-degree rotation of a crankshaft.
3.6. BLOCK DIAGRAM
Fig.3.6 Block diagram
3.7 FUNCTION OF PARTS
3.7.1. COMPRESSOR
Fig 3.7.1. Single Stage Compressor 2 Horse Power
The function of air compressor is to increase the pressure of air at desire level by using electric power. This is a picture of single stage air compressor. Specification of compressor is:-
Voltage 415 v
Current 3 A
R.P.M. 1440
Horsepower 2 H.P
Frequency 50 Hz
Table 3.7.1. Specifacation Of Compressor
3.7.2. STORAGE TANK
Fig 3.7.2. Air storage tank
The function of storage tank is to store high pressure compressed air.
Dimensions 1555*620*1300 mm
Tank Capacity 240 L
Pressure Capacity 15 Bar
Table 3.7.2. Air Storage Tank Specification
3.7.3. NOZZLE
The function is to connect and supply from tank to hose pipe.We can controll the flow of air by regulating by black wheel handle.
Fig.3.7.3. Nozzle
Outside Diameter 6mm
Inside Diameter 4mm
Table 3.7.3. Nozzle
3.7.4. HOSE PIPE
Fig.3.7.4. Hose Pipe
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The function of hose pipe is to convey a compressed from tank to inlet manifold. Specification of hose pipe is
Outside diamter of large pipe 8 mm
Inside diamter of large pipe 6 mm
Length of large pipe 1 m
Outside diamter of small pipe 6 mm
Inside diamter of small pipe 4 mm
Length of small pipe 1 m
Table 3.7.4. Hose Pipe
3.7.5. CONNECTOR
The function of connector is to connect 8 mm diameter hose pipe to 6 mm hose pipe.
3.7.5. Connector
3.7.6. CONNECTING PLATE
The function of connecting plate is to connect intake manifold and hosepipe
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Fig.3.7.6. Connecting plate
3.7.7. PRESSURE GAUGE
The function of pressure gauge is to indicate the pressure of air.
Fig.3.7.7. Pressure Gauge
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3.7.8 TACHOMETER
Fig.3.7.8 Tachometer
3.7.8. COMPRESSED AIR ENGINE
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Fig.3.7.8. Compressed air engine
CHAPTER 4: DESIGN
4.1. DESIGN OF ENGINE PARTS
4.1.1. PISTON
Material Aluminum alloy
Diameter 50mm
Total Height 39.2mm
Pin Hole 13mm
4.1.1. Piston
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4.1.1. Piston
4.1.2. CYLINDER BLOCK
Material Aluminium alloy
Height 96mm
Width 68mm
Depth 96mm
4.1.2. Cylinder block
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4.1.2 Cylinder Block
4.1.3. CONNECTING ROD
Material Low carbon steel 30C8
Outer diameter of big end 38.84mm
Inner diameter of big end 30.1mm
Thickness of big end 5mm
Depth of big end 14mm
Total length of connecting rod 120mm
Outer diameter of small end 16.5mm
Inner diameter of small end 13.04mm
Depth of small end 14mm
Thickness of small end 2.1mm
4.1.3. Connecting rod
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4.1.3. Connecting rod
4.1.4. CAMSHAFT
Diameter of small bearing 28mm
Diameter of big bearing 42mm
Thickness of small bearing 7mm
Thickness of big bearing 9mm
Shaft diameter 20mm
Camshaft length 70mm
Cam height 5mm
Cam thickness 10mm
4.1.4. Camshaft
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4.1.4.1. Camshaft
4.1.4.2. Modified Camshaft
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4.1.5. CRANKSHAFT
Small bearing diamter 51.8mm
Big bearing diameter 91.2mm
4.1.5. Crankshaft
4.1.5. Crankshaft
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4.1.6. COMPRESSED AIR ENGINE ASSEMBLY
4.1.6. Compressed Air Engine Assembly
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