1.0 INTRODUCTION
1.1 Basics of Energy:
As
we know that there are two types of energy sources;
1. Renewable
Energy Sources (Non-Conventional Energy Sources)
2. Non-Renewable
Energy sources (Conventional Energy Sources)
Renewable
Energy is energy which comes from natural resources and quantity is unlimited
such as sunlight, rain, tides, and geothermal heat, which are in-exhaustible in
nature. It is gave the free of cost in the nature.
Non-Renewable
Energy resources is natural resources which cannot be reproduced, grown,
generated, or used on a scale which can sustain its consumption rate, once
depleted there is no more available for future needs. Ex. Fossils fuels such as
petrol, diesel, kerosene, natural gas, petroleum gas, coal, coke etc.
Nowadays
in all over the world the transportation is mainly depends on fuels mainly like
petrol, diesel, LPG, CNG etc., which are Non-Renewable Energy Sources. These
sources are limited and decreasing day by day. The more demand and shortage
make it costly. It is remaining for few years. And it`s also harmful for
environment and human health.
Due
to these disadvantages in future use of Renewable resources are increase.
Renewable energy resources in are large availability and it is obtained free of
cost. Renewable energy resources are eco-friendly. For this advantages but it
contained certain disadvantages regarding to transportation purpose. It is very
difficult to implement the renewable sources for transportation purpose. Use of
these resources makes vehicle design complicated.
Due to the shortage of
Non-Renewable sources so, we are decided to develop an application which is
based on the Renewable resources. So we arte decided to use compressed air
instead of fossils fuel in our project. So, we are decided to making an application
which is based on concept name “COMPRESSED AIR ENGINE “.
1.2 Basics of Compressed Air Engine:
A
Compressed Air Engine is a pneumatic actuator that crates useful work by
expanding compressed air. A compressed air vehicle (CAV) is powered by an air
engine, using compressed air, which is stored in tank. Instead of mixing fuel
with air and burning in the engine to drive the piston with hot expanding
gases, compressed air vehicle (CAV) use the expansion of compressed air to
drive their piston.
They
have existed in many forms over the past two centuries, ranging in size from
hand held turbines up to several hundred horse power. For example, the first
mechanical powered submarine, the 1863 plongeur, used a compressed air engine.
The
laws of physics dedicate that uncontained gases with 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 tight inside, but the moment you use the pin to
create the hole in the balloon surface, the air expands outward with so much
energy that the balloon explodes. Compressing the gas into small space is way
to stored energy. When the gas expands again, that the energy is released to do
work. That is the basic principle behind what makes an air cargo.
Some
types rely on piston 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
Manufacture claims to have designed an engine that is 90 percent efficient.
Compressed air propulsion may also be incorporated in hybrid system, e.g.,
battery electric propulsion and fuel tank to recharge the batteries. This kind
of system is called hybrid pneumatic electric propulsion. Additionally,
regenerative braking can also be used in conjunction with the system.
Pneumatic
air engine have existed in many forms over the past two centuries, ranging in
size from hand held turbines to engine of up to several hundred horsepower.
Some type rely on pistons and cylinders, others use turbines. Many compressed
air engine improve their performance by heating the incoming air, or engine
itself. Pneumatic engine have found success in hand held tool industry and use
the transportation industry. However, pneumatic motors must overcome
inefficiency before being seen as a viable option in the transportation
industries.
A
compressed air engine is the type of motor which does mechanical work by
expanding compressed air. Pneumatic motors generally convert the compressed air
to mechanical work through the following types:
- Linear Motion
- Rotary Motion
2.0 LITERATURE SURVEY
For
half a century the air-powered locomotives was a serious contender for the top
spot in transportation, because it`s advantages, simplicity, safety, economy
and cleanliness. Air engine were commercially available and used routinely,
first as Metropolitan steer transit and later for haulage in mines.
Fig 2.1Locomotive of Oskar
H. W. Coester
Fig 2.2 Locomotive of Merarski
Robert Hardie And General Herman
Haupt et al [3] has
presented the model of compressed air locomotive in 1892-1900. Robert Hardie`s
air engine was going concern in street transits in New York City. Air car
advocate General Herman Haupt, a civil engineer, wrote extensively about the
advantages of air cars, using the Hardie engine as his source material and
proving much of the impetus for the New York experiment to gain support and
succeed. The engine was one-stage expansion engine using a more advanced type
of re heating then the Mekarski engine. One of its new feature was regenerative
braking. By using the engine as a compressor during the deceleration, air and
heat were added to the tank, increasing the range between fill-ups. A 1500
horsepower steam powered air compressor station was built in New York City to
supply the Hardie compressed air locomotives and the Hoadley-Knight pneumatic
locomotives.
Fig 2.3 Locomotive of Robert Hardie And General Herman
Haupt
Hoadley And Knight et al [4] has
presented the model of two stage Compressed Air Locomotives in 1896-1900. The
Hoadley And Knight system was the first air powered transits locomotive that
incorporated a two-stage engine. It was beginning to be recognized that the
longer you keep the air in the engine, the more time it has to absorb the heat
that increase its range between fill-ups. Hoadley and Knight were also
supporters of Nikola Tesla`s disc turbine, for which they formed a propulsion
company that did not get off the ground.
Fig 2.4 Locomotive of Hoadley and Knight
H.K. Porter et al [5] has presented the model
of compound air locomotives in 1896-1930. The inventor Charles B. Hodges became
the first and only air car inventor in history to see his invention become a
lasting commercial success. His engine was two-stage and employed an inter heater
between the two piston stages to warm
the partially expanded compressed air with the surrounding atmosphere. A
substantial gain in rage between fill-ups was thus proven attainable with no
cost for the extra fuel, which was provided by the sun. The H.K. Porter in
Pittsburg sold hundreds of these locomotives to coal mining companies in the
eastern U.S. with the hopeful days of air powered street transits over, The
compressed air locomotives became a standard fixture in coal mines around the
world, because it created no heat or spark and was therefore invaluable in
gassy mines where explosions were always a danger with electric or gas
engines.
Fig 2.5 Locomotive of H.K. Porter
Hodges Patents et al [6] has presents the model
of three stage Air Locomotives in 1912-1930. Hodges` patents were improved upon
by European engineers who increased the number of expansion stages to three and
used inter heaters before all three stages. The coal mines of France and
Germany and other Countries such as Belgium were swarming with these
locomotives, which increased their range-between fill-ups 60% by the addition
of ambient heat. It might have become obvious to the powers that be that these
upstarts were a threat to the petroleum takeover that was well under way in the
transportation industry; after world war two the terms “Air Engine” was never
used in compressed air textbooks and air powered locomotives, if used at all,
were usually equipped with standard, inefficient air motors.
Fig 2.6 Pneumatic Diesel Hybrid Locomotive
Terry Miller et al [8] has represent the
various improvement of design in Air Car. He was also knoen as a “The Father Of
The Modern Air Car Movement”. In 1979, Terry Miller set out to design a spring
powered car and determined that compressed air, being a spring that does not
break or wear out, was the perfect energy-stored in medium. From these
developed is air car one, which he built for $1500 and patented. He showed his
air car from coast and then went on to other thing. In 1993 he picked up his
car project again with help of Toby Butterfield of Joplin, Missouri. They
developed the spirit of Joplin air car with parts mostly donated with the
manufacturers. Terry`s air engine demonstrated the feasibility of building air
engine with off-the-shelf parts on a smaller budget. His engines used up to
four consecutive stages to expand the same air over and over. They ran at allow
speed so there was plenty of time for ambient heat to enter the system and the
possibility of low-tech developers to build engines cheaply at home. Terry was
instrumental in educating the founder of pneumatic Options on air car
fundamentals. Terry`s Greatest contribution and what make him an air car
advocate, not just another inventor- Was that he published and made easily
available the complete detail on how to build an engine like his. No other
inventor has done this. Shortly before his death in 1997, Terry Miller gave all
right to his invention to his daughter and Mr. Toby Butterfield died in 2002.
Fig 2.7 Compressed Air car of Terry Miller
Guy Negre and Moteur Development
International et al [9] has
represented the modern air car design. Currently a French inventor named Guy
Negre is building an organization to market his car design in several
countries. A web search for air cars will turn up hundreds of references to his
company, Moteur Development International (MDI). His website is www.mdi.lu. Mr.
Negreholds patents on his unique air engine in several countries. Plans are
underway to build the air car factory in Mexico, South Africa, Spain, and other
countries. We wish him success and encourage you to visit the website (or one
of his licensees in Spain, Portugal, and Great Britain) and supported his good
work. Plans are underway to build air car factories in Mexico, South Africa,
Spain and other countries.
C.J. Marquand et al [10] have presented the
improvement in the design of the Air car. Dr. Marquand has taken the highly
commendable step into incorporating heat pipes into his air engine design for
the recovery of compression heat. He also plans to use regenerative braking. It
is not clear that his engine has been tested in a car yet. Professor Marquand
is a scientist with a number of
published research articles to his credit. For further information contact:
C.J. Marquand or H.R. Ditmore, Department of Technology & Design,
University of Westminster.
Fig 2.8 Compressed air bicycle of Armando Regusci
3.0 DESCRIPTION OF COMPONENTS
Following are the various parts used in the project.
- . Solenoid Valve
- . Two stroke petrol engine
- . Air compressor
- . Supporting structure or Frame
- . Bearing
- . Shaft
- . Piping for compressed air
- . Measuring instruments
- . Drum
3.1 Solenoid Valve:
1. Valve Body 4.
Coil / Solenoid 7. Plunger
2. Inlet Port 5. Coil Windings 8. Spring
3. Outlet Port 6. Lead Wires 9. Orifice
The solenoid valve mechanism
shown in figure 3.3. It can be use to supplied compressed air in engine at
regular interval. In figure when the solenoid valve is connected to the battery
by cam mechanism the magnet can be excited and generate the electromagnet force
so plunger can be move upward direction and compressed air is passed left to
right. And battery is disconnected the plunger moves
downward Direction so path of air is closed.
3.2 Two stroke petrol engine:
Two stroke engine of BAJAJ CHETAK of around 150 cc. is used.
Fig 3.4 Schematic diagram of 2 stroke engine
We
are using the two stroke engine instead of four stroke engine because the all
stroke is completed in one crank revolution so the output speed is more. Here,
we are first discussing about the working of the compressed air engine.
Stages of two stroke
engine:-
Stage
1:
When
the piston is at Top dead center (T.D.C.) at this time an air is injected
in
cylinder through the intake port.
Stage
2:
When
the piston start the movement T.D.C. to bottom dead centre (B.D.C.) the intake
valve is closed and compression of an air is begins.
Stage
3:
When
the piston is arrive at the B.D.C. the compressed air is moved upward through
the transfer port.
Stage
4:
When
the piston is moved B.D.C. to T.D.C. the exhaust port is open and air is moved
outside.
Fig 3.4 Working diagram of 2 stroke engine
3.3 Air Compressor:
Fig 3.5 Reciprocating compressor
An air compressor is as device that can convers power (usuallly from and electric motor, a diesel engine or a gasoline engine) into kinetic energy by compressing and pressurizing air, which on command, can be released in quick burst. There are numerous methods of air compression, devided into either positive displacement or negative displacement typs.
The image of the air compressor is shown in figure. The Air compressor can be use to the increase the pressure of the air. The generally in market the air compressor is available in two types-Reciprocating and rotary air compressors. We are use the reciprocating type air compressor which can generate 10 to 12 bar pressure for running the engine successfully.
There are basic three types of air compressor.
The image of the air compressor is shown in figure. The Air compressor can be use to the increase the pressure of the air. The generally in market the air compressor is available in two types-Reciprocating and rotary air compressors. We are use the reciprocating type air compressor which can generate 10 to 12 bar pressure for running the engine successfully.
There are basic three types of air compressor.
Reciprocating
Air Compressors
Reciprocating air
compressors are positive
displacement machines,
meaning that they increase the pressure of the air by reducing its volume. This
means they are taking in successive volumes of air which is confined within a
closed space and elevating this air to a higher pressure. The reciprocating air
compressor accomplishes this by a piston within a cylinder as the compressing
and displacing element. Single-stage (70 psig to 100 psig.)
and two-stage (100 psig to
250 psig.) reciprocating compressors are commercially available.
Rotary
Screw Compressors
Rotary air compressors
are positive displacement compressors. The most common rotary
air compressor is the single stage helical or spiral lobe oil flooded screw air
compressor. These compressors consist of two rotors within a casing where the
rotors compress the air internally. There are no valves. These units are
basically oil cooled (with air cooled or water cooled oil coolers) where the
oil seals the internal clearances.
Rotary screw air
compressors are easy to maintain and operate. Capacity control for these compressors
is accomplished by variable speed and variable compressor displacement. Advantages of the rotary screw
compressor include smooth, pulse-free air output in a compact size with high
output volume over a long life.
Centrifugal Compressors
The
centrifugal air compressor is a dynamic compressor which depends on transfer
of energy from a rotating
impeller to the air.
Centrifugal compressors produce high-pressure discharge by converting angular
momentum imparted by the rotating impeller (dynamic displacement). In order to
do this efficiently, centrifugal compressors rotate at higher speeds than the
other types of compressors.
These
types of compressors are also designed for higher capacity because flow through
the compressor is continuous. The centrifugal air compressor is an oil free
compressor by design. The oil lubricated running gear is separated from the air
by shaft seals and atmospheric vents.
3.4 Supporting Structure:
The
supporting frame is required to hold the overall system .The all parts of
compressed air engine should be mounted on the frame. The supporting frame should minimize the vibration
of the system and improve the system life. In market the generally frame is
available in two types.
-Wooden
frame
-Metal frame
The wooden frame is use in our
project because the cost is low, No corrosion problem is occurred, noise less,
less weight compared to the metal frame.
3.5 Bearings:
Bearing is provided to support the rotating member
of the system.
Bearing also provides the frictionless rotation of
the shaft.
Following are various types of bearings available.
- . Ball Bearing
- . Pedestal Bearing
- . Collar Bearing
- . Pivot Bearing
- . Roller Bearing etc.
A proper bearing is selected according to properties
desired.
Various bearings mentioned above are shown in figure
below.
Fig 3.7 Ball bearing Fig 3.8 Pedestal bearing
Fig
3.9 Collar Bearing Fig. 3.10 Pivot bearing
Fig 3.11 Roller bearing
The type of bearing is selected according to its
suitability of features in the work desired.
In our project it also works as support to the
rotating shaft. The selection of bearing is generally based on the following
parameters.
- According to Allowable bearing space
- According to Load capacity and bearing type
- According to Permissible speed and bearing type
- According to Misalignment of inner and outer rings
- According to Rigidity and bearing types
- According to torque and noise
- According to running accuracy
- According to mounting and dismounting of bearing.
3.6 Shafting:
Shaft is used to transmit power as well as torque.
Various types of shafts are available.
Generally shafts are made from metals like cast
iron, aluminum alloy, steel are used.
The shaft can be made of solid cross-section as well
as hollow cross-sections.
Generally the hollow cross-section of shaft has more
strength compared to solid shaft of same diameter.
The cross-section area of the shaft and material of
the shaft is selected according to the static and dynamic load on the shaft.
Following are various materials used for shaft.
1. Alloy
steel
2. Plain
Carbon Steel
·
Hot rolled plain carbon steel
·
Cold drawn plain carbon steel
If there is a need of more hardened shaft then the
case hardening, carburizing, nitriding etc processes are used.
Fig 3.12 Solid shaft Fig
3.13 Hollow shaft
3.7 Piping for compressed air:
Various types of piping are used for compressed air.
- . Plastic pipe
- . Metal pipe
·
Aluminum pipe
·
Copper pipe
·
Steel pipe
·
Stainless steel pipe
·
Galvanized pipe
·
Extruded aluminum pipe
- Thermoplastic pipe
Thermoplastic pipe is
used because of its light weight, non corrosiveness and flexibility.
3.8 Measuring Equipments:
Various instruments required to measure various
parameters of the system are as given below.
- . Dynamometer
- . Tachometer
- . Pressure Gauge
3.8.1 Dynamometer:
Dynamometer is used to measure the brake power of
the engine by measuring the torque of the system.
Various types of dynamometers are used for measuring
the torque.
Following are various types of dynamometers.
- . Dry friction dynamometers
- . Hydraulic dynamometers
- . Eddy current type dynamometers
- . Engine dynamometers
- . Chassis dynamometers
A dynamometer is an instrument used for measuring
the power exerted by a source or the amount ofpower consumed by load.
The following two types of dynamometers are considered.
1)
Absorption
type
This type of
dynamometer measures torque and power by dissipating mechanical energy and are
suitable for power measurement of engines (such as internal combustion and gas
turbine engines) and electrical motors (ac and dc).
It includes Prony
brake, water brake, cradled electric motor dynamometers.
2) Driving type
This type of
dynamometer measures torque and power and supply energy to operate the device
being tested. This is convenient for testing such devices as pumps and
compressors, which require a driving source. A rotating electric machine can be
used as a driving dynamometer.
3.8.2 Techometer:
Tachometer is used to measure the rotational speed
of the shaft.
Fig 3.14 Revolution
counter Fig. 3.15 Digital
tachometer
Tachometer can be classified on the basis of data acquisition – contact or noncontact types
They can also be classified on the basis of the measurement technique – time based or frequency based technique
They can be also be classified as analog of digital type.
Analog Tachometer
· Has a needle and dial type of interface
· No provision for storage of readings
· Cannot compute average, deviation etc
.
Digital Tachometer
· Has a LCD or LED readout.
· Memory is provided for storage.
· Can perform statistical functions like averaging.
Contact type
· The Tachometer has to be in physical contact with the rotating shaft.
· Preferred where the tachometer is generally fixed to the machine.
· Generally, optical coder, magnetic sensor is attached to shaft of tachometer.
Noncontact type
· The Tachometer does not need to be in physical contact with the rotating shaft.
· Preferred where the tachometer needs to be mobile.
· Generally, laser is used or an optical disk is attached to rotating shaft and read by a IR beam or laser.
Tme Based
· The tachometer calculates speed by measuring the time interval between pulses.
· More accurate for low speed measurement.
· Time to take a reading is dependant on the speed and increases with decrease in speed.
· The resolution of the tachometer is independent of the speed of the measurement.
3.8.3 Pressure Gauge:
Pressure gauges are used to measure the pressure.
Fig 3.16 Pressure gauge
4.0 PART SPECIFICATIONS
4.1 Two stroke petrol engine:
We purchased a Bajaj Chetak scooter and disassembled
the engine. An engine has capacity of 150 cc.
We remove the unnecessary components from engine to
reduce its weight.
We disassembled the following components.
· Carburetor
· Gearbox
· Kick gear
· Fly wheel
· Magnets and coils
4.2 Solenoid Valve:
We have used a one way solenoid valve with following
specifications.
•
Type :
One Way
•
Orifice Diameter :
8 mm
•
Operating Voltage : 24
V (DC)
•
Pressure Range :
0 to 10.6 bar
•
Input / Output Hole Diameter :
1/8”
Operating
Mechanism for solenoid valve:-
The operating mechanism for solenoid valve can be of
two types.
1. Contact
type
2. Noncontact
type
In contact type mechanism the cam and follower
mechanism for connecting and disconnecting the valve from circuit is used.
For noncontact type mechanism the infrared receiver
and photo diode is used to connect and disconnect the circuit form solenoid
valve.
Following are the description of the circuit used
for connecting and disconnecting the solenoid valve from voltage supply with
the help of infrared receiver and photo diode.
Circuit
Component And Working:-
Circuit
is the very crucial part in our system. The circuit can be use to operate the
24 volt DC solenoid valve for the supply of air in the regular intervals in Two
stroke reciprocating cylinder. In our project “Emitter – Receiver circuit” can
be use to operate the solenoid valve at regular intervals. This circuit is
operated at 230 volt AC supply. In the circuit the 230 volt DC supply is
converted into 24 volt DC supply. The circuit is work in the principle of the
sense the signal between two diode namely, Emitter diode and receiver diode. So
the transducer Receiver circuit can be operated solenoid valve at 24V DC.
The
various component can be use to make the transducer receiver circuit to
operating the effective manner. So the following type of various element can be
use in the circuit.
1. Printed
Circuit Board (PCB board)
2. 18v
Transformer
3. Photo
diode
4. Transistor
5. Main
cord
6. Heat
sink
7. 6
V relay
8. Rectifier
9. Capacitor
10. Resistor
So this component can be use in the circuit. The Description of each component can be
discussed below.
1.
Printed circuit board (PCB Board):-
Figure
4.1 - Printed circuit board (PCB)
A
circuit board is a card made especially for attaching electronic components.
The board is made of a material that does not conduct electricity, like fiber
glass or plastic. Parts are then attached to this base using a conductive
bonding material. This allow to electricity travel from one part to another,
which is essential for the board to work. Inside the board the various
component can be attached like the transformer, heat sink, transistor,
capacitor, resister.
So
the PCB (Printed circuit board) is used to mechanical supports of the
electrical components. So now the all electronic equipment use the printed
circuit board (PCB) For attaching and supporting the various component of the
electrical system. Simple PCB board as shown in figure.
2.
18 volt Transformer:-
Figure4.2
- Transformer
A Transformer is a static electrical device that
transfer energy by the inductive coupling between the winding circuit. A
varying current in the primary winding
creates a varying magnetic flux in the transformers core and thus a varying
magnetic flux through the secondary winding. This varying magnetic flux induces
a varying electromotive force or voltage on secondary winding. The principle of
transformer as shown in figure.
Figure4.3
- Working Principle of transformer
The figure shows the basic working principle of
transformer and cross sectional view of transformer. The primary and secondary
winding is winded around the transformer core. When the current passed the
primary coil the EMF can be generated and magnetic effect can be generated so
the voltage can be induced in the secondary coil.
This voltage can be used in operating of solenoid
valve. So the solenoid valve is essential element of the system.
3.
Photo Diode:-
Figure
4.4 - Photo Diode
A
photodiode is a type of photo detector capable of converting light into either
current or voltage, depending upon the mode of operation. Photodiodes are
similar to regular semiconductor diodes except that they may be either exposed
or packaged with a window or optical fiber connection to allow a light to reach
the sensitive part of device.
Principle
of operation:-
Figure
4.5– Principle of operation of photo diode
A photodiode is p-n junction or PIN junction. When a
photon of sufficient energy strikes the diode, it excites an electron, thereby
creating a free electron. This mechanism is also known as inner photo electric
effect. If the absorption occur in the junctions depletion region. Thus holes
move toward the anode, and electrons towards the cathode, and photocurrent is
produced.
In our project the emitter diode and transmitter
diode can be use. The emitter is emit the electron, where receiver receive the
electrone.
Figure
4.6 – Emitter Receiver diode
4.
Transistor:-
Figure
4.7- Transistor
A Transistor is a semiconductor device used to
amplify and switch electronic signals and electric power. It is compressed of
semiconductor material with the least three terminals for connection to an
external circuit. A voltage or current applied to one pair of the transistor`s
terminals change the current through another pair of terminals. Because of the
controlled power can be higher than the controlling the power, a transistor can
amplify the signal.
Figure
4.8– Construction of transistor
The
essential usefulness of a transistor comes from its ability to use a small
signal applied between one pair of its terminals to control a much larger
signal at another pair of terminals. This property is called gain. A transistor
can control its output in proportion to the input signal. It`s consist the
Emitter, Base and Collector as shown in figure.
5.
Main cord:-
Figure
4.9 – Main cord
The
figure shows the main cord can be use in the circuit to supply the input AC
230V power to transformer. The two pin power cord can be use in our project to
supply the electric alternative current (AC current) to the transformer. The
main cord should be with stand the chemical action, safety core of fiber to
prevent the electric shock, etc.
6.
Heat sink:-
Figure
4.10– Heat sink
The
electronic system, a heat sink is a passive heat exchanger component that cools
a device by dissipating heat into the surrounding air. In computers, heat sink
are used to cool central processing unit or graphic processor. Heat sinks are
used with high-power semiconductor devices such as power transistor and photo
electronic device such as lasers and Light emitting diode (LEDs), where the
heat dissipation ability of the basic device is sufficient to control its
temperature.
A
heat sink design to increase the surface area in contact with cooling medium
surrounding it, such as the air. Approach of air velocity, choice of material,
fin design and area of contact.
A
heat sink transfer thermal energy from a higher temperature to a lower
temperature fluid medium. The fluid medium is frequently air, water,
refrigerants and oil. Heat sink of the electronic device must have a
temperature higher than the surrounding to transfer the heat by conduction,
convection and radiation.
7.
Six Volt relay:-
Figure
4.11– 6V relay
A
Relay is electrically operated switch. Many use in electromagnet to operate a
switching mechanism mechanically, but other operating principles are used.
Relay are used where it is necessary to control a circuit by a low-power
signal, or where several circuit must be controlled a circuit by a low-power
signal or where several circuits must controlled one signal. The first relay
were used in long distance telegraph circuit, repeating the signal coming in
from one circuit and re-transmitting it to another.
A
type of relay that can handle the high power required to directly control an
electric motor or other is called contactor. The following type of main relay
is available:
- Latching
Relay
- Reed Relay
- Mercury
wetted relay
- Polarized
relay
- Coaxial
relay
- Solid state
relay
- Overload
protection relay
In our project the solid state relay can be use . A
solid state relay including the heat sink used where frequent on/off cycles are
required. There are no moving part to wear out and there is no vibration.
8.
Rectifier:-
Figure
4.12- Rectifier
A
rectifier is an electric device that converts alternating current (AC) to the
direct current (DC). So the rectifier converts the reverse direction polarity
into the single direction or one direction polarity.
9.
Capacitor:-
Figure
4.13 - Capacitor
A
capacitor is a passive two terminal electrical component used to store energy
in an electric fluid. The forms of practical capacitor are widely used, but all
contain at least two electrical conductor separate by a dielectric.
When
the potential difference across the conductor, a static electrical field
develop across a dielectric, causing positive charge to collect on one plate
and negative charge on the other plate. Energy stored in the electrostatic
fluid.
10.
Resistor:-
A
resistor is a passive two terminal electrical component that implements
electrical resistance as a circuit element. The current through a resistor is
in direct proportion to the voltage across the resistor terminals. The
relationship of Ohm`s law is :
I = (V/R)
Where;
I = Current through a conductor (Amperes);
V = Potential difference measured across the
conductor (Volts);
R= Resistance of conductor (Ohms)
Figure
4.14-Resistor
The ratio of the voltage applied across the
resistor`s terminals to the intensity of current in the circuit is called its
resistance, and this can be assumed to be a constant for ordinary resistors
working within their ratings.
Working
Of Circuit:-
When there is an obstruction between the emitter and
receiver, the circuit is not connected to the solenoid valve so the voltage is
not supplied to the solenoid valve so the valve does not operate so the air
cannot pass through it.
When there is no obstruction between the emitter and
receiver, the circuit is connected to solenoid valve and voltage is supplied to
the solenoid valve so the solenoid valve opens and the air can passed through
it.
These two conditions are shown in the fig. below in
which the two cases discussed above is shown practically.
(a)
(b)
Figure
4.15 -operating circuit diagram for solenoid valve
4.3 Shafting:
Shaft
is used to transmit rotation or power produced in the engine. We are going to
use shaft has one end is attached to the engine crank shaft and another end is
kept open for any further use.
In market there are many options
according to material to choose shaft. There are mainly two possibilities,
either mild steel shaft or cast iron shaft. We are preferred the mild steel
shaft. Following image shows the actual arrangement of shaft connection.
Fig.4.16
Coupling of shaft to engine crank shaft
The
above image shows the arrangement of one end of shaft with the engine shaft.
The further extension of the shaft is supported by the bearings. There are two
pedestal bearing is used in our project to give support to the shaft. It is
also possible to use only one shaft for supporting purpose, but actually there
is lot of vibration is occur in the running of the engine which causes the
unbalancing of bending of the shafting to some degree, which causes the error
in the operation.
·
Dimensions
of the shaft
Length = 580mm
Diameter
= 24mm
Fig.4.17 Length of shaft carries
different another components
As
per shown in the above figure 580mm shaft is carrying two pedestal bearing
which have centre distance is about 310mm. The first bearing is at the distance
of 140mm from the engine shaft connection. There is a pulley is placed in
between the centre of the two bearing. Measurement of Brake Power is carried
out by using this pulley. A leather belt is rolled over this pulley for finding
the B.P. by using the dynamometer. This figure shows the how much load is to be
put on the shaft. So it is very necessary to use two pedestal bearings to
overcome the thrust produced by the system.
Diameter
of the engine crank shaft is tapered, so we have to go make attachment by doing
taping in the one end of the shaft. The following figure shows the end of the
shaft which carried to make operations regarding to the sensors and circuit.
There is some provision is needed to fit cut section of disc, which is working
for the receiving or transmitting sensing radiations for open and close the
solenoid valve. This arrangement of circuit is explain in detailed in the
separate sections related to their working.
Fig.4.18 Other end of the shaft used for circuit arrangement
Above
figure shows the cutting section of the disc. This portion of the shaft is also used to attach
tachometer to measure the speed for carried out some calculations.
There are various operations carried out on the shaft. Like,
- Turning
- Tapping
- Cutting
- Facing
- Drilling
and punching
Above operations are performed on the
shaft to make fit it on the diameter of the engine crank shaft and on the
bearing. So, it is very necessary to choose the material which can give good
machining ability.
Facing is the first operations making on
the shaft. We are buy shaft having around more length than usage. So it is very
necessary to cut the shaft to reduce its weight. Almost 3.5kg weight is exists
now in the operation of the engine. Very less weight is not able to storing the
energy like flywheel, which is very necessary to keep moving after each stroke.
The engine crank shaft have tapered
diameter with starting from 8mm section. So, it’s necessary to make the one end
of the shaft with reducing diameter from 24mm to suitable diameter which can
fit the shaft on the engine shaft. So, we can make the attachment by following
these methods
·
By welding
·
By tapping operation
First we are going to try the connections
by welding. We are carried out welding operation in our college workshop by
taking help of our guide and workshop incharge. But by welding, perfect centre
is not possible causes eccentricity the shaft. This makes uneven rotation of
the shaft. Due to this high degree of vibration are occurring in the system
makes the frames weak. So, after testing we are remove the welding and once
again turning and facing is make on the shaft. So, we finally drop the idea of
the welding of two shafts.
Another idea is by create the tapping
operations on the shafts. To make this action possible we are use pap of size
3/8. In this operation there is no worry about centre of the shaft and
eccentricity. We are going to take help of fabricator outside the college.
To fit the
bearings on the shaft drilling is carried out on the proper distance of the shaft. There are very
problems are faced in operations related to shafts which are described below in
detailed.
- Problem
related to the matching centre of the shaft
- Problem
related to design frame on the basis of create proper shaft height
- Problem
related to the decide place of the bearing to make optimum use of shaft
length
- Problem
related to weight and friction
As discussed above that it is very tough
to make zero eccentricity attachment when matching the centre of the shafts.
Selection of proper size is also a issue, because it create improper rotation
of the shaft. So shaft assembly should provide with proper height on the frame.
In our project we have to make number of operations on the shaft. So, it must
be design the frame structure and place of support bearings in the way of long
life use without any failure. Another thing is that we have to make optimum use
of the length of the shaft which is possible by put the bearings on proper
distance. Weight and friction has noticeable effect on the efficiency of the
shaft. So it is compulsory reduce the weight and friction on the every
attachments on the shaft. Following are the characteristics should fulfill by
shafting in our project, because any error in this component should directly affect
the performance of the system.
·
It should have less weight.
·
There should be minimum friction
at bearing and pulley.
·
Centre of the two shafts should
correctly match
·
It should posse’s good machine
ability.
4.4 Bearing:
We use two pedestal
bearing to support the shafting.
The bearing has
diameter 25 mm.
Fig.4.19
pedestal bearing
4.5 Drum:
- CONSTRUCTION
- SIZE
- MODIFICATION
- OPERATION
Fig:4.20 drum
1.
CONSTRUCTION
·
We had buy drum
of mild steel.
·
It was generated
through casting process.
2.
SIZE
·
The diameter of
drum is 200 mm.
·
The width of
drum is 110 mm.
·
The drum has hub
for shaft mounting is 25mm.
·
The drum has
weight of 6 kg.
3.
MODIFICATION
·
We have reduced
the width of drum through up to 50 mm.
·
We have reduced its
weight up to 2.5 kg.
4.
OPERATION
· We have
performed milling operation to decrease
of width up to 50 mm.
· We have
performed drilling operation on the periphery of drum for the weight reduction.
· We have
performed turning operation for the further removal of weight of drum.
· By above
processes we have reduced weight of drum up to 2.5 kg.
4.6 Frame:
·
Frame is
supporting structure to held different components like engine, shaft, bearing
etc.
·
The frame should
be designed that less vibration and shock occurred in the structure.
DETAILS OF FRAME.
- Details of frame consist following data.
- Material
- Size of frame
- Dimension of frame
- Operation
1.
MATERIAL
·
The frame is
made of mild steel channels.
2.
SIZE OF FRAME
·
The frame is
made of channel of mild steel as explained above.
·
The dimension of
channel is 5 x 5 mm.
·
The thickness of
channel is 2.5 mm.
Fig 4.21 : Frame
3.
DIMENSION OF FRAME
·
Length of
Frame - 850 mm.
·
Width of
Frame - 400 mm.
·
Height of Frame
Ø For bearing support - 260 mm.
Ø For dynamometer
- 850 mm.
4.
OPERTATION.
·
First of all we
have buy the channel of 25 ft length.
·
Then we have cut
it into different size according to frame design.
·
The cutting
operation done on power hack saw
machining.
·
Done drilling
operation on frame for the fastening.
·
The cutting
section welded through electric arc welding according to frame design.
·
Different parts
were mounted on the frame through fastening.
4.7 Connectors:
Following are
the details of connector used.
Fig 4.22 connectors
Connector
Details :
• Compressor Outlet : ½
“
• Solenoid Valve Input : ¼
“
• Solenoid Valve Output : ¼
“
• Engine Input :
¼
“
5.0 EXPERIMENTAL SETUP
- The engine is mounted on the frame with the help of bolts and nuts.
- Connectors are connected to the compressor outlet, solenoid valve inlet and outlet and inlet of engine.
- A pipe is connected from the compressor outlet to the solenoid valve inlet.
- Another pipe is connected from solenoid valve outlet to engine inlet.
- The dynamometer is mounted on the frame near the free end of shaft.
- The disc is cut to 900 to 1300 recess and mounted on the free end of shaft.
- The emitter and receiver are mounted at the suitable position at the disc.
- The circuit is connected to power supply.
- Disc is set to the desire position according to the T.D.C. and B.D.C. of the piston.
5.0 EXPERIMENTAL PROCEDURE
- First of all set up the equipment as mentioned above.
- Now switch on the compressor.
- Wait until the compressor pressure reaches up to 10.5 bar.
- Switch off the compressor.
- Now open the outlet valve of the compressor.
- Arrange the sensors at initial position such that the circuit is disconnected or the solenoid alve remains close.
- Now give initial start to the engine with the help of drum.
- The engine starts running.
- Now measure the r.p.m. of the engine at various pressures from 10.5 bar to 6 bar with the help of tachometer.
- Now again charge the compressor up to desired pressure at 10.5 bar.
- Now take readings of weight W1 and W2 of dynamometer at corresponding pressure and rpm.
- Calculate the torque from the data obtained.
- Calculate the Brake Power (B.P.) from the value of torque.
6.0 CALCULATIONS
6.1 Inspection Tables:
For crank angle =1350
Pressure
(bar)
|
Speed
(RPM)
|
Weight(W1)
kg
|
Weight(W2)
kg
|
10.50
|
560
|
3
|
3.5
|
10.00
|
520
|
2.5
|
3
|
9.50
|
460
|
2
|
3
|
9.00
|
440
|
1.5
|
2.5
|
8.50
|
410
|
1.5
|
2.5
|
8.00
|
380
|
1.5
|
2.5
|
7.50
|
370
|
1.5
|
2
|
7.00
|
350
|
1
|
2
|
6.50
|
330
|
1
|
1.7
|
6.00
|
315
|
1
|
1.5
|
5.50
|
292
|
0.5
|
1.5
|
Table 7.1 Inspection table for
crank angle 1350
For
Crank Angle = 900
Pressure
(bar)
|
Speed
(RPM)
|
Weight(W1)
kg
|
Weight(W2)
kg
|
10.50
|
520
|
2
|
3.5
|
10.00
|
490
|
2
|
3
|
9.50
|
470
|
1.5
|
3
|
9.00
|
450
|
1.5
|
3
|
8.50
|
430
|
1.5
|
3
|
8.00
|
410
|
1.5
|
3
|
7.50
|
400
|
1.5
|
2.8
|
7.00
|
360
|
1.5
|
2.8
|
6.50
|
330
|
1.5
|
2
|
6.00
|
300
|
1.5
|
2
|
5.50
|
280
|
2
|
3.5
|
Table 7.2 Inspection table for
crank angle 900
SAMPLE CALCULATIONS:
For 1350
angle
Pressure ‘P’ =
10.5 bar
Speed ‘N’ = 560 rpm
W1 = weight
reading on first indicator of dynamometer = 3 kg
W2 = weight
reading on second indicator of dynamometer = 3.5 kg
So,
W = W1 + W2
= 3 + 3.5
= 6.5 kg
Now,
Diameter of the
drum = 200 mm = 0.2 m
Now the torque,
T = W * D/2
= 6.5 * 0.2/2
= 6.5 * 0.1
= 0.65 Nm
Now, Brake Power
at this torque,
B.P. = (2*3.14*N*T)/60
= (2*3.14*560*0.65)/60
= 2285.92/60
= 38.11 W
This calculation
is done at every reading obtained.
The data
obtained through the calculations are summarized in the Result Table.
7.0 RESULTS
For crank angle =1350
Pressure
(bar)
|
Speed
(RPM)
|
Torque
(Nm)
|
Brake Power
(Watt)
|
10.50
|
560
|
0.65
|
38.11
|
10.00
|
520
|
0.55
|
32.25
|
9.50
|
460
|
0.50
|
27.02
|
9.00
|
440
|
0.40
|
23.03
|
8.50
|
410
|
0.40
|
18.61
|
8.00
|
380
|
0.40
|
15.91
|
7.50
|
370
|
0.35
|
13.56
|
7.00
|
350
|
0.30
|
10.99
|
6.50
|
330
|
0.27
|
9.33
|
6.00
|
315
|
0.25
|
8.24
|
5.50
|
292
|
0.20
|
6.11
|
Table 7.3 Result table for crank
angle 1350
For
Crank Angle = 900
Pressure
(bar)
|
Speed
(RPM)
|
Torque
(Nm)
|
Brake Power
(Watt)
|
10.50
|
520
|
0.55
|
29.95
|
10.00
|
490
|
0.50
|
25.66
|
9.50
|
470
|
0.45
|
22.14
|
9.00
|
450
|
0.45
|
21.20
|
8.50
|
430
|
0.45
|
20.26
|
8.00
|
410
|
0.45
|
19.32
|
7.50
|
400
|
0.43
|
18.01
|
7.00
|
360
|
0.43
|
16.21
|
6.50
|
330
|
0.35
|
12.09
|
6.00
|
300
|
0.35
|
10.90
|
5.50
|
280
|
0.35
|
10.26
|
Table 7.4 Result table for crank
angle 900
For
Crank Angle=135
Speed
VS Pressure
Speed
|
560
|
520
|
460
|
440
|
410
|
380
|
370
|
350
|
330
|
315
|
292
|
Pressure
|
10.5
|
10.0
|
9.5
|
9
|
8.5
|
8.0
|
7.5
|
7.0
|
6.5
|
6.0
|
5.5
|
Torque Vs Speed
Brake
Power Vs Pressure:-
For crank Angle =135
Brake
Power
|
38.11
|
32.25
|
27.02
|
23.03
|
18.61
|
15.91
|
13.56
|
10.99
|
9.33
|
8.24
|
6.11
|
Pressure
|
10.5
|
10.0
|
9.5
|
9.0
|
8.5
|
8.0
|
7.5
|
7.0
|
6.5
|
6.0
|
5.5
|
For
crank Angle =90
Speed
Vs Pressure:-
Torque
Vs Speed:-
Brake
power Vs Pressure:-
Brake
power
|
29.95
|
25.66
|
22.14
|
21.20
|
20.26
|
19.32
|
18.01
|
16.21
|
12.09
|
10.90
|
10.26
|
Pressure
|
10.5
|
10.0
|
9.5
|
9.0
|
8.5
|
8.0
|
7.5
|
7.0
|
6.5
|
6.0
|
5.5
|
8.0 CONCLUSION
Brake Power
(B.P.) and R.P.M. of a “Compressed Air Engine” is greatly depend upon the
following reasons.
·
Orifice diameter of Solenoid valve
·
Pressure of inlet air of engine
So compressed
air engine produces adequate R.P.M. but the load carrying capacity of engine is
very poor.
The load
carrying capacity of the engine can be increased by using high pressurized air
or by increasing the orifice diameter of the solenoid valve.
The Brake Power
(B.P.) of the engine is also considerably low.
So, by using
smaller orifice diameter of solenoid valve, adequate speed is achieved but the
torque generation, Load carrying capacity and Brake Power of engine is
considerably lower than the I.C. engine.
9.0 FUTURE SCOPE
As we know that
the “Compressed Air Engine” not required any conventional fuel and it is pollution
free engine, so future scope of this concept is bright same as the other
nonconventional systems.
By increasing
the storing capacity of compressed air in the system the automobiles run for
larger distance may be practically possible.
The successful
automobile system may be organized if proper refueling stations for compressed
air are made and high efficient automobiles can be made.
The compressed
air concept can be also used by driving automobile with rotary systems like
turbine.
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