HOW TO MAKE COMPRESSED ENGINE FROM TWO STROKE PETROL ENGINE

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.

The turm “Air Engine” disappeared from engineering textbooks after the 1930s and the Second World War. Gas engines had been perfected, the oil industry was established, and gas was cheap.

Serious interest in air cars was rekindled by the energy glitches of the 1970s. Dozens of inventors have patented design for hybrid, closed cycle, and self fueling air cars, as well as conversions for existing engines and designs for air cars meant to stop at air station for refueling.

Now, the various survey on compressed air engine is following:

Oskar H.W. Coester et al ^[1] has presented the model of an Areomovel global corp. In the modern electric subway trains the power supply was provided continuously by a pipeline laid along the truck. This concept was not practical at the n time it was invented (1820s), because the material were not available to make it work reliably. So the modern version appeared in Brazil in the 1980s, invented by Oskar H.W. Coester, and developed by Aeromovel Global Corp.

Fig 2.1Locomotive of Oskar H. W. Coester

Mekarski et al ^[2] has presented the model of Compressed air locomotive in 1886-1890. It was used for street transit. It was a single-stage engine (Air expanded in one piston then exhausted) and represented an advance in air engine technology that made air cars feasible: the air was reheated after leaving the tank and before entering the engine. The re heater was a hot water tank through which the compressed air bubbled in direct contact with water, picking up hot water vapour which improved the engine`s range between fill-ups. 

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.

German Diesel et al ^[7] has present the model of the Pneumatic Hybrid Locomotives in 1930. Just before technical journals stopped reporting on compressed air locomotives, they carried stories on a 1200 horsepower full size above ground locomotives that had been developed in Germany. An on board compressor was run by a diesel engine, and the air engine drove the locomotives wheels. Waste heat from the diesel engine was transferred to the air engine were it became fuel again. By conserving the heat in this way, the train`s range between fill-ups was increased 26%. A modern train engineer tells me that all train engines these days are hybrid: Diesel-electric. And we are supposed to consider the Toyota Prius a miracle of modern invention?

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.

Tsu-Chin Tsao et al ^[11] has presented the model of the hybrid air engines of Car. Tsu-Chin Tsao is a distinguished professor of mechanical and aerospace engineering at UCLA. He has invented a cam less gasoline engine that does not idle; it uses compressed air to start the car, and when the air is gone the engine runs on gasoline. During Deceleration, breaking energy operates a compressor to fill the air tank for the next start. This brings to mind Buckminster Fuller`s reminder in his magnum opus Critical Path, wherein he tell us how many horsed (as in horsepower) could be jumping up and down going nowhere for all the gasoline being pointlessly burns by a cars sitting at a red lights at any given time. We have nothing but admiration and respect for professor Tsao`s serious step in a perfectly good direction and apparently Ford Motor Company is an agreement: they are working with Tsao`s team to look into the viability of putting a pneumatic hybrid on the road compete with Toyota Prius and other electric hybrids. The pneumatic hybrid is expected to save 64% in city driving and 12% on highway.

Angelo Di Pietro et al ^[12] has presented the concept of rotary positive displacement Air Engine. He gave The space between the stator and rotor is divided in six expansion chambers by pivoting dividers. These dividers followed the motion of the shaft driver as it rolls around the stator wall. The motor shown is effectively a six cylinder expansion motor. Variation of performance parameters of the motor is easily achieved by varying the time during which the air is allowed to enter the chamber. A longer air inlet period allows more air to flow in to the chamber and there for result in more torque. A shorter inlet period will limit the air supply and allow the air in the chamber to perform the expansion work at the much higher efficiency. In this way compressed air(Energy) consumption can be exchange for higher torque and power outputs depending upon the requirement of the application. Motor Speed and torque ars simply controlled by throttling the amount or pressure of air into the motor. The Di Pietro motor give instant torque at Zero RPM and can be precisely controlled to give soft start and acceleration control.

Armando Regusci et al ^[13] have presented the model of Air cycle. His invention does away with the crankshaft using sprocket and chains and freewheeling clutches to turn a shaft. He has built a bike and small air car of various descriptions and is vary devoted to the cause.

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

The description of various parts are given below.

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.

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.

1. .      Dynamometer
2. .      Tachometer
3. .      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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