RUN SI ENGINE BY USING COMPRESSED AIR

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1.1 INTRODUCTION
At first glance idea of running an engine on air seems to be too good to be true. Actually if we
can make use of air as an aid for running an engine it is a fantastic idea. As we all know, air is all
around us, it never runs out, it is non-polluting and free.
A Compressed-air engine is a pneumatic actuator that creates useful work by compressed air. A
Compressed-air vehicle is powered by an air engine, using compressed air, which is stored in a tank.
Instead of mixing fuel with air and burning it in the engine to drive piston with hot expanding gases,
compressed air engine (CAE) use the expansion of compressed air to drive their pistons.
They have existed in many forms over the past two centuries, ranging in size from hand hed
turbines up to several hundred horsepower. For example, the first mechanically powered submarine,
the 1863 Plongeur, used a compressed air engine.
The laws of physics dictate that uncontained gasses will fill any given space. The easiest way to
see this in action is to inflate a balloon. The elastic skin of the balloon holds the air tightly inside, but
the moment you use a pin to create a hole in the balloon’s surface, the air expands outward with so
much energy that the balloon explodes. Compressing a gas into a small space is a way to store
energy. When the gas expands again, that energy is released to do work. That’s the basic principle
behind what makes an air cargo.
Some types rely on pistons and cylinders, others use turbines. Many compressed air engines
improve their performance by heating the incoming air, or the engine itself. Some took this a stage
further and burned fuel in the cylinder or turbine, forming a type of internal combustion engine.
One manufacturer claims to have designed an engine that is 90% efficient. Compressed air
propulsion may also be incorporated in hybrid system, e.g., battery electric propulsion and fuel tanks
to recharge the batteries. This kind of system is called hybrid-pneumatic electric propulsion.
Additionally, regenerative braking can also be used in conjunction with this system.

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Fig: 1.1
1.2 LITERATURE REVIEW
HISTORY
(A) The first compressed-air vehicle was devised by Bompas, a patent for a locomotive being taken
out in England in 1828. There were two storage tanks between the frames, with conventional
cylinders and cranks. It is not clear if it was actually built. (Knight, 1880)
(B) The first recorded compressed-air vehicle in France was built by the Frenchmen Andraud and
Tessie of Motay in 1838. A car ran on a test track at chaillot on the 9th July 1840, and worked
well, but the idea was not pursued further.
Fig: 1.2

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(C) In 1848 Barin von Rathlen constructed a vehicle which was reported to have been driven from
Putney to Wandsworth (London) at an average speed of 10 to 12 mph.
(D) At the end of 1855, a constructor called julienne ran some sort of vehicle at Saint- Denis in
France, driven by air at 25 atmosphere (350 psi), for it to be used in coal mines.
(E) Compressed air locomotive were use of haulage in 1874 while the Simplon tunnel was being
dug. An advantage was that the cold exhaust air aided the ventilation of the tunnel.
(F) Louis Mékarski built a standard gauge self-contained tramcar which was tested in February
1876 on the Courbevoie-Etoile Line of the Paris Tramways Nord (TN), where it much
impressed the current president and minister of transport Maréchal de McMahon. The tramcar
was also shown at the exhibition of 1878 as it seemed to be an idle transport method, quiet,
smooth, without smoke, fire or the possibility of boiler explosion.
(G) The compressed air locos were soon withdrawn due to a number of accidents possibly caused by
licking in the pipes of the brakes, which were also worked by compressed air.
COMPRESSED AIR TECHNOLOGY
Air can be compressed into small volumes and can be stored in suitable containers at high pressure.
Such air compressed into containers is associated with an amount of energy. When the stored
compressed air is released freely it expands thereby releasing the energy associated with it. This
energy released can be utilized to provide useful work. The compression, storage and release of the
air together are termed as the compressed air technology. This technology has been utilized in
different pneumatic systems. This technology has been undergoing several years of research to
improve its applications.

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components
COMPONENTS USED
2.1 COMPRESSOR
It is a device which converts mechanical energy into fluid energy. The compressor increases the air
pressure by reducing its volume which also increases the temperature of the compressed air. The
compressor is selected based on the pressure it needs to operate and the delivery volume.
 Air compressor governor: Controls the cut-in and cut-out point of the air compressor to
maintain a set amount of air in tank or tanks.
 Air reservoir tanks: Hold compressed or pressurized air to be use to run SI engine.

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Fig: 2.1
 Drain valves: Release valve in the air tanks used to drain the air moisture.
 Solenoid valve: It is an electromechanically operated valve, the valve is controlled by an
electric current through a solenoid, in the case of a two port valve the flow is switched on or
off. Solenoid valves are the most frequently used control elements in fluid, it energized with
electromagnetic coils.
Specification:
Made : ISO 9001 company
kPa : 1-11 Bar
Lb/in2
: 0-180 PSI
2.2 DESCRIPTION OF MECHANICAL COMPONENTS
 Description of Components of Compressed Air Engine:
Various Mechanical parts used in engine are:
1. Crank shaft
2. CAM shaft
3. Piston cylinder
4. Valves

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5. Connecting rod
6. Roller bearing
7. Timing gear
8. Nozzle
Description of Mechanical Parts:
CRANK SHAFT
The crankshaft, sometimes casually abbreviated to crank, is the part of an engine which
translates reciprocating motion into rotary motion or vice versa. Crank shaft consists of the shafts
part which revolve in the main bearing, the crank pins to which the big ends of the connecting rod
are connected, the crank webs or cheeks which connect the crank pins and the shaft parts.

9
Fig: 2.2-1
Crank shaft can be divided into two types:
1. Crank shaft with side crank or overhung crank
2. Crank shaft with a centre crank
A crank shaft can be made with two side cranks on each end or with two or more centre cranks. A
crank shaft with only one side crank is called a single throw crank shaft and the one with two side
cranks or two centre cranks as a multi throw crank shaft.
The overhung crank shaft is used for medium size and large horizontal engines. Its main advantage
is that only two bearing are needed, in either the single crank or two crank, crank shafts.
Misalignment causes most crank shaft failures and this danger is less in shafts with two bearing than
with three or more supports. Hence, the number of bearing is very important factor in design. To
make the engine lighter and shorter, the number of bearings in automobiles should be reduced.
For the proper functioning, the crank shaft should fulfill the following condition:
1. Enough strength to withstand the forces to which it is subjected i.e. the bending and twisting
moments.
2. Enough rigidity to keep the distortion a minimum.
3. Stiffness to minimize and strength to resist, the stress due to torsional vibrations of the shaft.
4. Sufficient mass properly distributed to see that it does not vibrate certainly at the speeds at
which it is operated.

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5. Sufficient projected areas of crank pins and journals to keep down the bearing pressure to a
value dependent on the lubrication available.
6. Minimum weight, especially in aero engines.
The crank shafts are made much heavier and stronger than necessary form the strength point of
view so as to meet the requirements of rigidity and vibrations. Therefore, the weight cannot be
reduced appreciably by using a material with a very high strength. The material to be selected will
always depend upon the method of manufacture i.e. cast, forged or built up. Built up crank shafts
are something used in aero engines where light weight is very important.
In Industrial engines, 0.35 carbon steel of ultimate tensile strength 500 to 525 MPa and 0.45 carbon
steel of ultimate tensile strength of about 627 to 780 MPa are commonly used. In transport engines,
alloy steel e.g. manganese steel having ultimate strength of about 784 to 940 MPa is generally used.
In aero engines, nickel chromium steel having ultimate tensile strength of about 940 to 1100 MPa is
generally used.
Failure of crank shaft may occur at the position of maximum bending; this may be at the centre of
the crank or at either end. In such a condition the failure is due to bending and the pressure in the
cylinder is maximal. Second, the crank may fail due to twisting, so the connecting rod needs to be
checked for shear at the position of maximal twisting. The pressure at this position is the maximal
pressure, but only a fraction of maximal pressure.
CAMSHAFT
A camshaft is a shaft to which a cam is fastened or of which a cam forms an integral part.
The relationship between the rotation of the camshaft and the rotation of the crankshaft is of critical
importance. Since the valves control the flow of the air/fuel mixture intake and exhaust gases, they
must be opened and closed at the appropriate time during the stroke of the piston. For this reason,
the camshaft is connected to the crankshaft either directly, via a gear mechanism, or indirectly via a
belt or chain called a timing belt or timing chain.

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The cam shaft not only opens and closes your valves to let air in and out, but determines when and
for how long the valves remain open. With this in mind, let’s talk about what happens as the engine
spins. What follows next in a basic explanation for four-cycle engine operation, described in
relation to the four valve events? For each rotation of the cam, we have four valve events. The crank
shaft rotates twice for each revolution of the cam shaft, so four valve events happen for every two
revolution of the engine in four stroke engine.
 Stroke 1 – Intake Valves Opening
The cam shaft opens the intake valve, and the piston moves down the cylinder. As the
pressure drops in the cylinder, the air starts moving past the intake valve to fill the culinder.
This period of the engine cycle is known as the intake stroke.
 Stroke 2 – Intake Valves Closing
At some point, usually after the piston reaches the bottom of the intake stroke, the intake
valve closes. The piston moves up the cylinder, beginning the compression stroke and
compressing the fuel/air mixture within. At some point, usually before the piston reaches the
top of the compression stroke, the spark plug ignites the mixture, causing it to burn and
expand rapidly. The crankshaft has rotated once at this point.
 Stroke 3 – Exhaust Valves Opening
After the piston reaches the top of the compression stroke, pressure from the burning,
expanding mixture pushes the piston back down the cylinder. The exhaust valve starts to
open, usually before the piston is all the way down, allowing some of the burnt gasses to
exit the cylinder. This is commonly referred to as the blow down phase. The piston begins to
move back up, forcing the rest of the hot gas out of the cylinder.
 Stroke 4 – Exhaust valve closing
As the piston moves back up the cylinder, the exhaust valve remains open , usually until
slightly after the piston reaches the top of the cylinder we refer to this as the exhaust stroke.
As the piston reaches the top again, intake valve begins to open again, the intake valve
begins to open, often before the exhaust valve is fully closed, and the whole cycle begins
anew. The period when both valves are open simultaneously is referred to as “overlap”. The
crank shaft has now gone around twice.
CAM NOMENCLATURE

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Fig: 2.2-2
 Trace point: A theoretical point on the follower, corresponding to the point of a fictitious
knife-edge follower. It is used to generate the pitch curve. In the case of a roller follower, the
trace point is at the centre of the roller.
 Pitch curve: The path generated by the trace point at the follower is rotated about a stationary
cam.
 Working curve: The working surface of a cam is in contact with the follower. For the knife-
edge follower of the plate cam, the pitch curve and the working curves coincide. In a close or
grooved cam there is an inner profile and an outer working curve.
 Pitch circle: A circle from the cam centre through the pitch point. The pitch circle radius is
used to calculate a cam of minimum size for a given pressure angle.
 Prime circle (reference circle): The smallest circle from the cam centre through the pitch
curve.
 Base circle: The smallest circle from the cam centre through the cam profile curve.
 Stroke or throw: The greatest distance or angle through which the follower moves o rotates.
 Follower displacement: The position of the follower from a specific zero or rest position
(usually it’s the position when the follower contacts with the base circle of the cam) in relation
to time or the rotary angle of the cam.
 Pressure angle: The angle at any point between the normal to the pitch curve and the
instantaneous direction of the follower motion. This angle is important in cam design because
its represents the steepness of the cam profile.

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CAMSHAFT TERMINOLOGY:
Camshaft terminology can sometimes between very confusing. The diagram below should
help to explain some of the terms used in the design and section of camshaft.
Fig: 2.2-5
1. Max Lift or Nose
2. Flank
3. Opening Clearance Ramp
4. Closing Clearance Ramp
5. Base Circle
6. Exhaust Opening Timing Figure
7. Exhaust Closing Timing Figure
8. Intake Opening Timing Figure
9. Intake Closing Timing Figure
10. Intake to Exhaust Lobe Separation

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PISTON
A piston is a component of reciprocating engines among other similar mechanisms. It is the
moving component that is contained by a cylinder and is made gas-tight by piston rings. In an
engine, its purpose is to transfer force from expanding gas in the cylinder to the crankshaft via
a piston rod and/or connecting rod.
The piston of an air compressed is acted upon by the pressure of the expanding combustion gases in
the combustion chamber space at the top of the cylinder. This force then acts downwards through
the connecting rod and onto the crankshaft. The connecting rod is attached to the piston by a
swiveling gudgeon pin. This pin is mounted within the piston: unlike the steam engine, there is no
piston rod or crosshead.
The pin itself is of hardened steel and is fixed in the piston, but free to move in the connecting rod.
A few designs use a 'fully floating' design that is loose in both components. All pins must be
prevented from moving sideways and the ends of the pin digging into the cylinder wall.
Fig: 2.2-6
Gas sealing is achieved by the use of piston rings. These are a number of narrow iron rings, fitted
loosely into grooves in the piston, just below the crown. The rings are split at a point in the rim,
allowing them to press against the cylinder with a light spring pressure. Two types of ring are used:
the upper rings have solid faces and provide gas sealing; lower rings have narrow edges and a U-
shaped profile, to act as oil scrapers. There are many proprietary and detail design features
associated with piston rings.

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CYLINDER
A cylinder is the central working part of a reciprocating engine, the space in which
a piston travels. A cylinder's displacement, or swept volume, can be calculated by multiplying its
cross-sectional area (the square of half the bore by pi) by the distance the piston travels within the
cylinder (the stroke). The engine displacement can be calculated by multiplying the swept volume
of one cylinder by the number of cylinders.
Fig: 2.2-7

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BEARING
The concept behind a bearing is very simple: Things roll better than they slide. The
wheels on your car are like big bearings. If you had something like skis instead of wheels, your
car would be a lot more difficult to push down the road. That is because when things slide, the
friction between them causes a force that tends to slow them down. But if the two surfaces can
roll over each other, the friction is greatly reduced.
Bearings reduce friction by providing smooth metal balls or rollers, and a smooth inner
and outer metal surface for the balls to roll against. These balls or rollers "bear" the load,
allowing the device to spin smoothly.
 Working of a Bearing
As one of the bearing races rotates it causes the balls to rotate as well. Because the balls
are rolling they have a much lower coefficient of friction than if two flat surfaces were
rotating on each other.
Ball bearings tend to have lower load capacity for their size than other kinds of rolling-
element bearings due to the smaller contact area between the balls and races. However,
they can tolerate some misalignment of the inner and outer races.
Compared to other rolling-element bearings, the ball bearing is the least expensive,
primarily because of the low cost of producing the balls used in the bearing.
Types of Bearings

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Cut away view of a ball bearing Cut away view of a roller bearing
There are many types of bearings, each used for different purposes. These include ball bearings,
roller bearings, ball thrust bearings, roller thrust bearings and tapered roller thrust bearings.
Ball thrust bearing Roller thrust bearing
Cutaway view of (left) a spherical roller thrust bearing and (right) a radial tapered roller bearing
Fig: 2.2-8

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Bearing Loads
Bearings typically have to deal with two kinds of loading, radial and thrust. Depending on where
the bearing is being used, it may see all radial loading, all thrust loading or a combination of
both.
Fig: 2.2-9
The bearing that supports the shafts of motors and pulleys are subjected to a radial load.
BEARING USED

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Fig: 2.2-10
A ball bearing is a type of rolling-element bearing which uses balls to maintain the separation
between the moving parts of the bearing. The purpose of a ball bearing is to reduce rotational
friction and support radial and axial loads. It achieves this by using at least two races to contain
the balls and transmit the loads through the balls. Usually one of the races is held fixed.
CONNECTING ROD
Connecting rod is a part of the engine which is used to transmit the push and pull from
the piston pin to the crank pin. In many cases, its secondary function is to convey the lubricating
oil from the bottom end to the top end i.e. from the crank pin to the piston pin and then for the
splash of jet cooling of piston crown. The usual form of connecting rod used in engines has an
eye at the small end for the piston pin bearing, a long shank, and a big end opening which is
usually split to take the crankpin bearing shells.
The connecting rods of internal combustion engine are mostly manufactured by drop forging.
The connecting rod should have adequate strength and stiffness with minimum weight. The
materials for connecting rod range from mild or medium carbon steel to alloy steels. In industrial
engines, carbon steel with ultimate tensile strength ranging from 550 to 670 MPa is used. In
transport engines, alloy steel having a strength of about 780 to 940 MPa is used e.g., manganese
steel. In aero engines, nickel chrome steel having ultimate tensile strength of about 940 to 1350
MPa is most commonly used.
For connecting rod of low speed horizontal engines, the material may be sometimes steel
castings. For high speed engines, connecting rod may also be made up of duralumin and
aluminum alloys.
The usual shape of connecting rod is:
• Rectangular
• Circular
• Tubular
• I section
• H section
In low speed engines, the section is usually circular with flattened sides, or rectangular, the larger

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dimension being in the plane of rotation. In high speed engines, lightness of connecting rod is a
major factor. Therefore tubular, I- section or H-section rods are used.
Fig: 2.2-11
The length of the connecting rod depends upon the ratio of connecting rod length and stroke i.e.
l/r ratio; on l/r ratio depends the angularity of the connecting rod with respect to the cylinder
centre line. The shorter the length of the connecting rod l in respect to the crank radius r, the
smaller the ratio l/r, and greater the angularity. This angularity also produces a side thrust of the
piston against the liner. The side thrust and the resulting wear of the liner decreases with a
decrease in the angularity. However, an increase of l/r ratio increases the overall height of the
engine. Due to these factors, the common values of l/r ratio are 4 to 5.
The stresses in the connecting rod are set up by a combination of forces. The various forces
acting on the connecting rod are:
1. The combined effect of gas pressure on the piston and the inertia of the reciprocating
parts.
2. Friction of the piston rings and of the piston.
3. Inertia of the connecting rod.

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4. The friction of the two end bearings i.e. of the piston pin bearing and the crank pin
bearing.
VALVES
In four stroke the “Poppet Valve” performed the opening of the cylinder to inlet or
exhaust manifold at the correct moment. Generally the face of valves is ground at 45 degree but
in some cases it is ground at 30 degree also. It is not important to have a same angle of face in
inlet and exhaust valve of same engines. To make it in right order, the valve may be reground
after some use. There is some margin provided to avoid sharp edges. The groove, retain the value
spring which aids in keeping the valve pressed against the seat when closed and thus seal the
combustion space tightly. In close position, the valve face fits the accurately matched ground
seat in the cylinder block. Generally replaceable ring inserts are used for exhaust valve seat.
The inlet valves are made from plain nickel, nickel chrome or chrome molybdenum.
Whereas exhaust valves are made from nickel chrome, silicon chrome steel, high speed steel,
stainless steel, high nickel chrome, tungsten steel and cobalt chrome steel.
A poppet valve (also called mushroom valve) is a valve typically used to control the
timing and quantity of gas or vapor flow into an engine. It consists of a hole, usually round or
oval, and a tapered plug, usually a disk shape on the end of a shaft also called a valve stem. The
portion of the hole where the plug meets with it is referred to as the 'seat' or 'valve seat'. The
shaft guides the plug portion by sliding through a valve guide.
Fig: 2.2-12

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The poppet valve is fundamentally different from slide and oscillating valves; instead of
sliding or rocking over a seat to uncover a port, the poppet valve lifts from the seat with a
movement perpendicular to the plane of the port. The main advantage of the poppet valve is that
it has no movement on the seat, thus requiring no lubrication.
Poppet valves are used in most piston engines to open and close the intake and
exhaust ports in the cylinder head. The valve is usually a flat disk of metal with a long rod
known as the 'valve stem' attached to one side.
The stem is used to push down on the valve and open it, with a spring generally being
used to return the valve to the closed position. At high revolutions per minute (RPM),
the inertia of the spring means it cannot respond quickly enough to return the valve to its seat
between cycles, leading to 'valve float' also known as 'valve bounce'. In this
situation desmodromic valves can be used which, being closed by a positive mechanical action
instead of by a spring, are able to cycle at the high speeds required in, for
instance, motorcycle and auto racing engines.

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TIMING GEAR
Timing Gear is a component of an internal combustion engine which is connected
by a chain, gears, or a belt to the crankshaft on one end and the camshaft on the other. It is
marked with tiny increments all around its perimeter which correspond to degrees of timing from
the straight-up timing position of the camshaft and crankshaft. These marks assist the individual
who is tuning up the engine to set the timing to the determined optimal timing degrees of the
camshaft and engine designers.
In order to set an engine's timing gear to the correct inclination, the mechanic must confer
with the engine manufacturer as well as the camshaft manufacturer. The purpose of timing an
engine with the timing gear is to ensure that the valve open and close at the correct time to best
fill the cylinder with an air/fuel mixture as well as to release all fumes from the exhaust cycle of
the cylinder. A mere few degrees off can be the difference between an engine that performs
perfectly and one that will not run correctly. A poor running engine will make less power and use
more fuel than a properly-timed engine.
Fig: 2.2-13

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While the timing gears rotates a full 360 degrees, the timing marks are concerned with
just a few degrees before and after top dead centre of the piston’s rotation. Top dead center is
when the piston is at its absolute highest point of travel within the cylinder or at the top of the
stroke at the dead centre of when the crankshaft is neither travelling up nor down in the cylinder.
The timing gear is used to measure the amount of rotation in degrees in relation to when the
valves begin to open and close.
NOZZLE
A nozzle is a device designed to control the direction or characteristics of a fluid flow
(especially to increase velocity) as it exits (or enters) an enclosed chamber or pipe via an orifice.
A nozzle is often a pipe or tube of varying cross sectional area and it can be used to direct
or modify the flow of a fluid (liquid or gas). Nozzles are frequently used to control the rate of
flow, speed, direction, mass, shape, and/or the pressure of the stream that emerges from them.
Frequently, the goal of a nozzle is to increase the kinetic energy of the flowing medium at
the expense of its pressure and internal energy.
Fig: 2.2-14
Nozzles can be described as convergent (narrowing down from a wide diameter to a smaller
diameter in the direction of the flow) or divergent (expanding from a smaller diameter to a larger
one).

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Compressed Air Engine and its Working:
The laws of physics dictate that uncontained gases will fill any given space. The easiest
way to see this in action is to inflate a balloon. The elastic skin of the balloon holds the air tightly
inside, but the moment you use a pin to create a hole in the balloon's surface, the air expands
outward with so much energy that the balloon explodes. Compressing a gas into a small space is
a way to store energy. When the gas expands again, that energy is released to do work. That's the
basic principle behind what makes an air car go.
The first air cars will have air compressors built into them. After a brisk drive, you'll be
able to take the car home, put it into the garage and plug in the compressor. The compressor will
use air from around the car to refill the compressed air tank. Unfortunately, this is a rather slow
method of refueling and will probably take up to two hours for a complete refill. If the idea of an
air car catches on, air refueling stations will become available at ordinary gas stations, where the
tank can be refilled much more rapidly with air that's already been compressed. Filling your tank
at the pump will probably take about three minutes.
The first air cars will almost certainly use the Compressed Air Engine (CAE) developed
by the French company, Motor Development International (MDI). Air cars using this engine will
have tanks that will probably hold about 3,200 cubic feet (90.6 kiloliters) of compressed air. The
vehicle's accelerator operates a valve on its tank that allows air to be released into a pipe and then
into the engine, where the pressure of the air's expansion will push against the pistons and turn
the crankshaft. This will produce enough power for speeds of about 35 miles (56 kilometers) per
hour. When the air car surpasses that speed, a motor will kick in to operate the in-car air
compressor so it can compress more air on the fly and provide extra power to the engine. The air
is also heated as it hits the engine, increasing its volume to allow the car to move faster.
India's Tata Motors will likely produce the first air car in the marketplace in the next few
years. Tata Motors' air car will also use the CAE engine. Although Tata announced in August
2008 that they aren't quite ready to roll out their air cars for mass production, Zero Pollution
Motors still plans to produce a similar vehicle in the United States. Known collectively as the
FlowAIR, these cars will cost about $17,800. The company, based in New Paltz, N.Y., says that
it will start taking reservations in mid-2009 for vehicle deliveries in 2010. The company plans to
roll out 10,000 air cars in the first year of production. MDI also recently unveiled the joystick-
driven AirPod, the newest addition to its air car arsenal. Although the AirPod generates a top
speed of only 43 mph, it's also extremely light and generates zero emissions.

29
Major automobile makers are watching the air car market with interest. If the first models catch
on with consumers, they'll likely develop their own air car models. At present, a few smaller
companies are planning to bring air cars to the market in the wake of the MDI-based vehicles.
These include:
• K’Airmobiles -- French company K'Air Energy has built prototypes of an air-fuelled
bicycle and light road vehicle based on the K'air air compression engine
• Air Car Factories SA -- This Spanish company has an air car engine currently in
development. The company’s owner is currently involved in a dispute with former
employer MDI over the rights to the technology.
Fig: 3.1 Fig:3.2
Fig: 3.3

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CHAPTER – 4
DESIgn of components

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DESIGN OF MECHANICAL COMPONENTS
4.1 Design of CAM Shaft:
Initially, we are having 4-stroke camshaft which do not works for our purpose (i.e.
Compressed Air Engine). Thus we converting 4-stroke into 2-stroke and made slight modification
in cam shaft. Previously it vas V-shaped for 4-stroke, now we converting this to I-shaped i.e. the
inlet and exhaust at 180°. Also for continuous supply of air, to generate more torque we shaped
OVAL-CAM to the individual side through 180° (i.e. in both inlet & exhaust-cams).
Fig: 4.1
4.2 Design of Timing Gear:
You take a 4-stroke engine, and make the following changes.

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Change crank and cam gear ratio to 1:1 instead of 2:1, so for every revolution of the crank, the cams
also turn once. Cams profiles have to be changed (new cams ofcourse).
Fig: 4.2 (Camshaft gear)
Fig: 4.3 (Valve Timing Diagram)
Valve timing as follows:
Inlet Valve Open – 10° before T.D.C
Exhaust Valve Open – 20° before B.D.C

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Inlet Valve Close – 10° after B.D.C
Exhaust Valve Close – 5° after T.D.C
Pressure of Compressed Air – 25 PSI
R.P.M of Crankshaft – `650-700 R.P.M
CHAPTER – 5
Advantages

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ADVANTAGES
The advantages are well publicized since the developers need to make their machines attractive to
investors. Compressed-air vehicles are comparable in many ways to electric vehicles, but use
compressed air to store the energy instead of batteries. Their potential advantages over other
vehicles include:
1. Much like electrical vehicles, air powered vehicles would ultimately be powered through
the electrical grid, which makes it easier to focus on reducing pollution from one source,
as opposed to the millions of vehicles on the road.
2. Transportation of the fuel would not be required due to drawing power off the electrical
grid. This presents significant cost benefits. Pollution created during fuel transportation
would be eliminated.
3. Compressed air technology reduces the cost of vehicle production by about 20%,
because there is no need to build a cooling system, fuel tank, Ignition Systems or
silencers.
4. Air, on its own, is non-flammable.
5. High torque for minimum volume.
6. The mechanical design of the engine is simple and robust.
7. Low manufacture and maintenance costs as well as easy maintenance.
8. Compressed-air tanks can be disposed of or recycled with less pollution than batteries.
9. Compressed-air vehicles are unconstrained by the degradation problems associated with
current battery systems.
10. The tank may be able to be refilled more often and in less time than batteries can be
recharged, with re-fuelling rates comparable to liquid fuels.
11. Lighter vehicles would mean less abuse on roads. Resulting in longer lasting roads.

36
12. The price of fuelling air-powered vehicles will be significantly cheaper than current
fuels.
CHAPTER – 6
Problems
&
Technological

37
Trends
6.1 PROBLEMS FACED DURING DESIGNING:
1. Availability of component of desired specification in market as per the design.
2. To vary the output speed.
3. To prevent the air leakage.
SOLUTION ADAPTED
1. As per market survey conducted by us we have selected the component with nearest possible
specification as per our design to get the desired output.
2. With the use of air tight joint formed by the connectors we prevent the leakage of air.
6.2 TECHNOLOGICAL TRENDS
In Europe inventors have made the simple air engine, thus opening the new field for compressed
air car technology. These engines allow the car to run compressed air instead of fuel. The super
compressed and powerful, pumps the pistons in the car instead of small gas explosions. Pumping
air instead of exploding gasoline means these car have zero emission motors –no pollution, no
oil. In addition, current average of family fuel is 60 dollars and half that for a hybrid car the new
air engine will give a whole week of diving for a few dollars. The company, MDI plans to sell
this clean fuel vehicle and a compressed air hybrid in Europe for less than 1500 dollars in near
future.
 To refit scoter with air compressor motor that is about three quarters of a foot in
diameter. In the engine schematics, a tank of compressed air fires into the chambers of a
turbine whose axis is set off centre from its housing. The vanes of turbine extends as they
rotate, allowing the chamber to accommodate the volume of air as it is expands and
contributes to drive. Unlike the air car, the retrofitted scooter would run off the pressure it
takes to fill a tire at a gas station. Although they are hoping to eventually solve
engineering problems related to torque and range for the scooter (which currently only

38
hold enough air to travel 18 miles), it might be while until they can really solve the
emission problem.
 An inventor in California (USA) has made a car running on compressed air, stored in
scuba diving tanks. He modified an engine used on Honda RC51998cc super bike. He
blocked off one of the cylinder of the engine and used the spark plug hole on the other
cylinder to feed the compressed air. The compressed air drives the piston down as the
power stroke. At the end of power stroke, the compressed air is released through the
exhaust valve and the exhaust is only air. The Piston was connected to the wheels through
the Honda bike’s six-speed transmission. This Modified engine was mounted on a
tubular frame and a body that looked like a curious crossbreed of a motorbike with a
racing car. A bank of the scuba tanks was used to store compressed air at3500 psi and
throttled it to 250 psi at the engine inlet with a self designed throttle valve, linked to the
accelerator pedal. The three tanks were sufficient for the test run over the 2 mile, where
an average speed of 46.723 mph was achieved with a top speed of 54.058 mph. Further a
speed to the level of 300 mph is expected with compressed air. However, several issues
like large size and heavy model due to the use of a number of tanks still remain before
this concept can translate into a usable idea.

39
6.3 DEVELOPERS AND MANUFACTURERS
Various companies are investing in the research, development and deployment of air cars. Most
of the cars under development also rely on using similar technology to low energy vehicles in
order to increase the range and performance of their cars. Here is a brief list of few leading
manufacturing who are putting their concerted efforts towards making compressed air vehicle a
reality of public use.
 APUQ (Association de Promotion des Usages de la Quasiturbine) has made the APUQ
Air Car, a car powered by a quasiturbine.
 MDI (Motor Development International)France has proposed a range of vehicles made
up of Air pod, One Floe Air, Mini Flow Air. One of the main innovation of this company
is its implementation of its “active chamber”, which is a compartment which heats air
(through the use of a fuel) in order to double the energy output.
 Tata Motors announced in may 2012 that they have assessed the design passing phase-1,
the “Proof Of Technical Concept” towards full production for the Indian market. Tata has
moved on to phase-2, “completing detailed development of the compressed air engine
into specific vehicle and stationary application”.
 Air car factories South Africa is proposing to develop and build compressed air engine.
 A similar concept using a pneumatic accumulator in a largely hydraulic system has been
developed by U.S government research laboratory and industry. It uses only compressed
air only for recovery of braking energy, and in 2007 was introduced for certain heavy
vehicle application such as refuse trucks.
 K’Airmobiles vehicle were intended to be commercialized from a project developed in
France in 2006-2007 be a small group of researchers.

40
6.4 PROBLEMS WITH COMPRESSED AIR
A compressed air vehicle is a type of alternative fuel vehicle which uses a motor powered by
compressed air. Compressed air cars are not yet available in most places but the Technology
behind them is being perfected so that they can be introduced in the market. These cars can be
powered solely by air or by a combination of air and fuel, such as diesel, ethanol, r gasoline
which is how a hybrid electric vehicle runs. Compressed air cars engine are fueled by a tank of
compressed air, instead of an engine that runs with piston and an ignited fuel air mixture.
Basically, compressed air cars are powered by the expansion of compressed air. Vehicles that run
on compressed air sound like a fantastic idea on paper, but brining this technology to be masses
have proven, well a difficult road to travel because of some inherited technical problems with
compressed air [2-4, 14, 18] the present articles give a brief report to highlight such problems so
that some method can be designed to counter to improve the efficiency of compressed air
vehicle.
 ENGINE TECHNOLOGY
The air power cars runs on a pneumatic motor that is powered by compressed stored on
board the vehicle. Once compressed air is transferred into the onboard storage tank, it is
slowly released to power the car’s piston. The motor then convert the air power into
mechanical power. That power is then transferred to the wheel and become the source of
power for the car. The engine that is installed in a compressed air car uses compressed
which s stored in the car’s tank at a pressure as a high as 4500 psi. The technology used
by air car engine is totally different from the technology that is used conventional fuel
cars. They used the pressure generated by the expansion of compressed air to run their
pistons.
 ENGINE STOREAGE & REFULING

41
The cars are designed to be filled up at a high pressure pump and thus the pump must be
designed to safety standards appropriate for a pressure vessel. The storage tank may be
made of metal or composite material. The fiber material are considerably lighter than
metal but generally more expansive. Metal tanks can withstands a large number of
pressure cycles, but must be checked for corrosion periodically. It may be possible to
store compressed air at lower pressure using an absorption material within the tank.
Absorption material such as activated carbon, or a metal organic frame work is used to
store compressed natural gas at 500 psi instead of4500 psi, which amount to a large
energy saving. One company stores air in tanks at 4,500 pounds per square inch (about30
Mpa) and hold nearly 3,200 cubic feet (around 90 cubic meters0. The tank may be filled
at a service station equipped with heat exchangers, or in a few hours at home or in a
parking lot, plugging the car in to the electrical grid via an on board compressor. The
Tata/MDI air ca version had 4,350 psi in its tank, which would require stations to install
new high-tech air pump, a difficult investment on station owner. As through by engineers
and designers, the storage tank may be made up of carbon fiber to reduce the car’s weight
and prevent an explosion in case of a direct collision. Carbon –fiber tanks are capable of
containing air pressure up to 4500 psi, something the something the steel tanks are not
capable for fueling the car tank with air, the compressor needs to be plugged into the car,
which would use the air that is around to fill the compressed air tank.
 TEMPRETURS CONTROL
In adiabatic process of compression of air, the heat of compression is retained, that mean
there is not heat exchange resulting in zero entropy change, so the compressed air
becomes very hot. Compressed air would experience a temperature rise due to the energy
that has been added to the gas by the compressor which can be controlled with isothermal
and adiabatic compression process. In an isothermal compression process, the gas in the
system is kept at a constant temperature throughout. This necessarily requires removal of
heat from the gas this heat removal can be achieved by heat exchangers (inter cooling)
between subsequent stages in the compressor. To avoid wasted energy, the intercooler
must be optimised for high heat transfer and low pressure drop. Naturally this is only an
approximation to a isothermal compression, since the heating and compression occurs in
discrete phase. Some smaller compressor can approximate isothermal compression even
without inter cooling, due to relatively ratio of surface area to volume and the resulting
improvement in heat dissipation from the compressor body itself. An adiabatic process is

42
one where there is no heat transfer between the fluid and the surroundings. The system is
insulated against the heat transfer. If the process is furthermore internally reversible
(smooth, slow and frictionless, to the ideal limit) then it will additionally be isentropic.
An adiabatic storage system does away with the intercooling during the compression
process, and similarly allows the gas to heat up during compression, and likewise to cool
down during expansion.
 POLLUTANT EMISSION
Like other non-combustion engine storage technology, an air vehicle displaces the
emission source from the vehicles tail pipe to the central electrical generating plant.
Where low emission source are available, net production of pollutants can be reduced.
Emission control measure at a central generating plant may be most effective and less
costly than treating the emission of widely dispersed vehicle. Since the compressed air is
filtered to protect the compressor machinery, the air discharge has less suspended dust in
it; through there may be carrying Over of lubricants used in the engine. The air powered
car would normally emit air, as it’s what it would solely use. But it would totally depend
on the purity of air that is put into the air tank as well as the temperature maintained
inside the storage tank during the process of compression. The rise in temperature of the
compressed air as a function of compressed pressure is shown in figure. As can be seen
from the figure, temperature rise significantly if the air is compressed single stage
without providing any facility in the tank to absorb the heat produced. This increase in
temperature can lead to the dissociation of air nitrogen part an its chemical reaction with
oxygen to produce unwanted gaseous compounds like NO, N2O, and NO3 in significant
concentrations. This type of emission can increase if impurity air is filled in.

43
Mathematical Calculations of Certain Parameters:
We know that the engine ‘indicated horse power’ (IHP) can be calculated as following,
1 HP = PmLAnk/60000
Where,
Pm = Mean Effective Pressure
L = Length of Stroke
A = Piston Cross Section Area
n = RPM of Crankshaft
k = Number of Cylinders
For our case,
Pm = Pressure at which the air is compressed
k = 1 (As there is only one cylinder present) “n” can be found using the Tachometer when
engine is running
“L” and “A” are specific for a given engine.
When we have the engine’s parameters (bore and stroke) and rpm, we can simply calculate the
engines I.H.P using the above mentioned formula.
Then we find the B.H.P using the dynamometer Torque.
Then the ratio of this I.H.P to B.H.P will give us the efficiency of our Engines as:

44
ɳ = B.H.P / I.H.P
The friction horse power will simply be the difference of B.H.P and I.H.P. To calculate the work
done we make use of formula:
Work done = m.e.p * Vd
Where, Vd is displacement volume of engine given by the following relation:
Vd = A*L (π/4*D2)
Now to calculate the engine torque we use the following relation: T= P/2nπ
CHAPTER – 7
CONclusion

45
CONCLUSION
This is a revolutionary engine design which is eco friendly, pollution free, but also very
economical. This redresses both the problems of fuel crises and pollution. However excessive
research is needed to completely prove the technology for both its commercial and technical
viability. It can be seen that the indicated power is increasing for increase of load. As load is
increased, the speed falls down, to maintain it constant injection pressure has to be increased. As
the injection pressure has to be increased, the indicated means effective pressure gets increased;
hence the indicated power is increased upon the application of the load. Though the applied load
was small, however, the developed power was in proportion to the applied load. As load was
applied the speed was reduced, to maintain it constant, the inlet air pressure has to be increased.
As shown injection pressure is increased. In the present case the speed was maintained constant
as 600 rpm. As the output speed was less the brake power was significantly lower. The
mechanical efficiency is increasing with the increase of output power. At lower output it was
very low.

46
WORK SCHEDULE
Sep-2017 In this month we planned for the project based on mechanical Non-
conventional m machining with some Automation to reduce human effort. All
the group members were involved in collecting ideas to make it from faculty
members of mechanical department as well as from internet.
Oct-2017 We collected many ideas but we selected the “Run SI Engine through
Compress Air”.
Nov-2017 We learned about the various types of material that are to be used.
Dec-2017 We started collecting the materials with required specification.
Jan-2018 During this month we designed a fabricated our materials for operation.
Feb-2018 We assemble the project completely.
Mar-2018 Tested it. As well as resolved all the technical problems during testing.
Apr-2018 The final experiment was conducted.

47
COST ESTIMATION
SI NO Name of Component Price
1. Engine 7,000
2. Air Compressor 6,000
3. CAM 1,500
4. Fly Wheel 500
5. Pinion (25 teeth) 300
6. Gear (25 teeth) 400
7. Frame 1,200
8. Miscellaneous 1,000
Total 17,900

RUN SI ENGINE BY USING COMPRESSED AIR

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