AIR CAR
PRESENTED BY
MOSES DHILIP KUMAR
9791301321
INDEX
·
ABSTRACT
·
WORKING PRINCIPLE
·
NEW ENGINE DESIGN
·
BENEFITS OF THE NEW DESIGN
ENGINE
·
THEORY BEHIND THESE CARS
·
P-V DIAGRAM
·
CHASSIS OF THE CAR
·
AIR TANKS
·
BODY OF THE CAR
·
PERFORMANCE
·
VEHICLE SPECIFICATION
·
CONCLUSION
ABSTRACT:
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.
WORKING PRINCIPLE:
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.
NEW ENGINE
DESIGN:
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.
BENEFITS
OF THE NEW DESIGN ENGINE:
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
|
THEORY
BEHIND THESE CARS:
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.
CHASSIS OF
THE CAR:
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.
AIR
TANKS:
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. 
BODY OF THE CAR:
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.
PERFORMANCE
OF AIR POWERED CARS:
Maximum
speed
60mph
Acceleration
0-30 mph: 7 seconds
Range
120 miles or 10 hours
|
Engine speed (rpm)
e.Volution
CARS:
|
Engine mount
|
Rear
|
|
Transmission
|
Automatic,
continuous variation.Rear wheel drive
|
|
Suspension
|
Front
coil spring, rear pneumatic
|
|
Steering
|
Rack
and pinion
|
|
Dimensions
|
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
|
CONCLUSION:
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.
REFERENCES:
1. MODERN COMPRESSIBLE FLOW by
J.D. Anderson.
2. JOURNAL OF ENGINES – SAE
Transactions.
3. AUTOMATIC TRANSIMISSION by P.M.
Heldt.
4. HIGH SPEED COMBUSTION ENGINES
by Newton and Steeds.
5. MODERN COMPRESSIBLE FLOW by
J.D. Anderson.
6. THE DYNAMICS AND THERMODYNAMICS
OF COMPRESSIBLE FLUID by . A.H.Shapiro.
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