Friday, 5 July 2013

aircar by moses dhilipkumar





·         ABSTRACT
·         P-V DIAGRAM
·         AIR TANKS
·         BODY OF  THE CAR
·         CONCLUSION


Considering that we live in a very mobile society, it's probably safe to assume that you have. While pumping gas, you've undoubtedly noticed how much the price of gas has soared in recent years. Gasoline, which has been the main source of fuel for the history of cars, is becoming more and more expensive and impractical (especially from an environmental standpoint). But cost is not the only problem with using gasoline as our primary fuel. It is also damaging to the environment, and since it is not a renewable resource, it will eventually run out. These factors are leading car manufacturers to develop cars fueled by alternative energies. One possible alternative is the air-powered car. There are at least two ongoing projects that are developing a new type of car that will run on compressed air. One among them is the e.Volution Cars.
                After more than thirty years experience with combustion engines, the French engineer Guy Negre has developed a concept of a totally non-polluting engine for use in urban areas. This invention, which uses high pressure (300 bar) compressed air to store the energy needed for running the engine. When the air is injected into the cylinder chamber, it expands to provide motive power.  Oddly, the problem with a conventional four-stroke engine is that compression, combustion and expansion all take place in a single cylinder.  But here the engine divides these functions into a three-chamber system, with one cylinder for compression, a small chamber for combustion and a much larger cylinder for expansion.
                    Zero Pollution Motors is also working on a hybrid version of their engine that can run on traditional fuel in combination with air. Mono-energy engine have demonstrated the viability of the new concept, the air and fuel, bi-energy, engine will be introduced to major car manufacturers in order to study its adaptation for their common models.

                   The e.Volution is powered by a two-cylinder, compressed-air engine.  The basic concept behind the engine is unique; it can run either on compressed air alone or act as an internal combustion engine. Compressed air is stored in carbon or glass fiber tanks at a pressure of 4,351 pounds per square inch (psi). This air is fed through an air injector to the engine and flows into a small chamber, which expands the air. The air pushing down on the pistons moves the crankshaft, which gives the vehicle power. A compressor driven by an electric motor connected to a standard electric outlet does the recharge of the compressed air tanks. A rapid recharge, using a high-pressure air pump, is also possible. The change of energy source is controlled electronically. When the car is moving at speeds below 60 kmph, it runs on air. At higher speeds, it runs on a fuel, such as gasoline, diesel or natural gas.
Guy Negre’s engine is, in fact, a radically new internal combustion engine. Two chambers, one for intake and compression and one for expansion and exhaust, are separated from a spherically shaped combustion chamber. The retention time in the combustion chamber is 30% to 100 % longer than in comparable conventional engines, thus giving rise to a more complete combustion at constant volume, while the spherical shape helps eliminate knock (which as been unknown in this engine).
At the heart of the engine is a small combustion chamber. A piston in a compression cylinder outside this chamber forces air through a valve; getting compressed and thus heating a mixture of air and petrol in the process. With all valves to the chamber closed the hot mixture is ignited. In the final part of the cycle the hot gas escapes through a valve into a separate expansion cylinder where it drives a piston cooling in the process.
v  One of the benefits of having separate compression and expansion cylinders is that the expansion cylinder can be made several times larger than the compression cylinder. This takes maximum advantage of the stroke that provides the engine's power.
v  Another benefit is that at the end of this expansion the gas is at atmospheric pressure and a temperature of only 100 degrees C. The output of conventional engines by contrast is usually at a pressure of several atmospheres and a temperature of 500 degrees C which means that lots of potentially useful energy is being thrown away and demands a complicated exhaust system to cool and depressurize the gases. As a result of these advantages, the engine is some 50% more efficient than the four-stroke variety.
v  The benefits of the design do not stop there. Because the expansion piston provides power at every second stroke rather than every fourth. The Engine provides the increased mechanical efficiency of the two-stroke engines common on motorcycles.
v  The design of the engine allows the fuel to burn over a period up to four times longer than in a four-stroke engine. The longer burn time means that the fuel is consumed far more completely leading to less in the way of unwanted by-products such as carbon monoxide and nitrogen oxides.
v  The pollution is much less and quieter because the explosion of the fuel happens in the small combustion chamber rather than being allowed to propagate through the cylinder as in conventional motors. The design also allows the engine to be light: fully functioning test versions weigh only  34kg. 
Intake and compression cylinder
230 cm³
Expansion and exhaust cylinder
500 cm³
Power max. HP-Cyl (kW-Cyl)
25 (18.3) at 3000 rpm
Torque max. Kgm-Cyl (Nm-Cyl)
6.3 (61.7) at 500 – 2500 rpm
Power source
Electronically injected compressed air

In principle the technology is very similar to the internal combustion system in that compressed air is used to drive a piston in a barrel. The secret of the engine lies in the way it efficiently converts the energy stored in the tanks of compressed air. By way of explanation, it has long been known that to compress air to high pressures a staged process should be used, compressing air to first 50 bars, then to 150 bars then three hundred and so on.
 This technique, commonly employed by the air and gas liquefaction industries, uses a fraction of the energy used to compress the gas in one operation. The secret of the compressed air motor is simply to reverse the process - decompress the air in stages and in so doing efficiently release energy at each point in the chain. To compensate for the cooling effect that takes place, a thermal exchanger heats the compressed air using the warmth of external air. This process is repeated as many times as possible to extract the maximum energy efficiency from the compressed air.
                                                                 For the somewhat technically minded, the following drawing illustrates the theoretical explanation for this process.
                                              PV DIAGRAM
The Isotherm, the green line, represents the ideal transformation of the compressed air: in effect, the air temperature is the same coming in and going out of the cylinder, and power is maximized.
On the contrary, the worst transformation is the adiabatic transformation, represented by the red line. The derived power is minimal, and the air leaves the system at a very low temperature indeed.
The blue line, or polytropic curve, represents the transformation that actually takes place, and the individual stages outlined above can be seen. The transformation going through the first cylinder is represented by the polytropic line (somewhere between our ideal isotherm and the adiabatic curve). The following temperature rise brings the line closer to the isotherm, and allows the second and subsequent stages to produce more power.
In other words, if we realize an adiabatic transformation no heat is exchanged between the external air and the compressed air meaning that the power produced is minimal. On the contrary, following the isotherm means a maximum exchange and the power so produced is optimized.

An alternate version of the MDI engine can function as a duel-fuel engine, using both air and a traditional fuel, such as gasoline, diesel fuel or natural gas, at very low consumption levels. In this engine type, the engine runs on air at speeds below 37 mph (60 kmph) and electronically switches to the traditional fuel at higher speeds.
In practical terms compressed air at 300 bars is stored in the carbon fibre tanks A. The air is released through the main line firstly to an alternator B where the first stage of decompression takes place. The now cold air passes through a heat exchanger C which adds thermal energy to the air and provides a convenient opportunity for air conditioning D. The warmed compressed air now passes to the engine E. where a two more stages of decompression and re-heating take place. The motor drives the rear axle G through the transmission F. Control of engine speed is through a conventional accelerator pedal H controlling a valve within the motor.
An energy recycler J is under tests which uses engine braking K to recompress air during braking into a secondary storage facility, providing additional energy for re-start and acceleration. Conventional hydraulic braking L is supplied. The vehicle can be refilled by using the onboard compressor M or by refilling the tank at an air station at N.
One of the most frequently asked questions regards the safety of the air tanks, which store 90m3 of air at 300 bars of pressure. Many people ask whether this system is dangerous in case of an accident, and whether there is an explosion risk involved. The answer is NO. Because the tanks are the ones already used to carry liquefied gases on some urban buses, and therefore make use of the technology that is already used to move buses on natural gas. That means that the tanks are prepared and homologated to carry an explosive product: methane gas. In the case of an accident, with air tank breakage, there would be no explosion or shattering, now that the tanks are not metallic. Due to the fact that they are made of glass fibre the tanks would crack longitudinally, and the air would escape, causing a strong buzzing sound with no dangerous factor. It is clear that if this technology has been tested and prepared to carry an inflammable and explosive gas, it can also be used to carry air.
A final matter with reference to the air tanks is the improvement that MDI contributed to the original structure. In order to avoid the so-called 'rocket effect', this means to avoid the air escaping through one of the tank's extremities causing a pressure leak that could move the car, MDI made a small but important change in the design. The valve on the buses’ tanks is placed on one of the extremities. MDI has placed the valve in the middle of the tank reducing the 'rocket effect' to a minimum. It takes about four hours for the motor-driven compressor to recharge the compressed air tanks. A rapid three-minute recharge is also possible, using a high-pressure air pump in any bunks.
Close up on refilling tanks with compressed air.
The car bodies of the MDI vehicles are made of glass fibre with injected foam, such as many other cars that are on the market nowadays. This technology brings in two main advantages: lower cost and less weight. These cars are provided with pneumatic suspension at the rear for more comfort .since the engine is mounted on rear ,front end of car is aesthetically  designed.

Maximum speed                                 60mph
Acceleration                                      0-30 mph: 7 seconds
Range                                                120 miles or 10 hours

Torque in kgm

In hp

Engine speed (rpm)

e.Volution CARS:
Engine mount
Automatic, continuous variation.Rear wheel drive
Front coil spring, rear pneumatic
Rack and pinion
Length 384 cm, width 172 cm, height 175 cm
Wheel base
292 cm
Weight: unloaded
About 700 kg
Chassis and body materials
Steel bars/ honeycomb plastic and fiber glass
Tanks for compressed air
Thermoplastic lining and carbon fiber
        Within the next two years, you could see the first air-powered vehicle motoring through your town. Most likely, it will be the evolution car that is being built by Zero Pollution Motors, in Brignoles, France. The cars have generated a lot of interest in recent years, and the Mexican government has already signed a deal to buy 40,000 e.Volutions to replace gasoline- and diesel-powered taxis in the heavily polluted Mexico , as  it has outstanding  advantages including  much fuel economy, eco-friendly, electronically controlled automatic transmission  and so on . As air is the only working medium upto 60 kmph, periodical cleaning of valves, tanks, injectors are necessary.   However proper maintenance helps us to keep the vehicle running smoothly.

2. JOURNAL OF ENGINES – SAE Transactions.
6. THE DYNAMICS AND THERMODYNAMICS OF COMPRESSIBLE FLUID by                                .   A.H.Shapiro.

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