It gives the brief introduction and working of an air powered vehicles with some images and vehicle models.

1. COMPRESSED AIR VEHICLES
THE FUTURE HYBRIDS
Submitted By
Maley Vamshi Kiran
AM.EN.U4ME11037
S6 ME-A

2. PAGE 1
Introduction:
In the present world every one is aware of the fact of diminishing amounts of fossil fuels (Petroleum Products). From the past 10 years it has been happening very rapidly. The global warming phenomenon also made us aware of the fossil fuel’s negative effect. What causes global warming? The gases exhausted by the automobiles contains CO, CO2, Nitrogen Oxides and unburned hydrocarbons etc., These gases causes pollution in the atmosphere also contributing in the depletion of ozone layer. In addition to this there are other factors causes global warming. These are the reasons which made our automobile manufacturers to think about the alternatives. This gave birth to Electric cars, Hybrid cars (which uses two type’s energy sources), Fuel cell powered vehicle, and Hydrogen fueled cars. The other possibility may be the vehicles which run by compressed air (since we are having plenty of air in our atmosphere) and it results in zero pollution. This cars run with compressed air (high pressure air) which is available at low cost. The usage of compressed air in pneumatic actuators, air motors has been known to everyone. Even in present Fuel Engines to enhance the power Turbocharging is done which works only on air. The research on usage of compressed air in engines is done a long back ago. In 1863 a submarine named Plongeur used a compressed air engine. Also, in 1879 airplane named The Victor Tatin used a compressed air engine for propulsion. Compressed air is gas which is treated under high pressure than the atmospheric air pressure.
How Compressed Air Fuel a Car:
When a gas is compressed to a small volume the energy is stored, when it expands the work is done by releasing the energy stored. In the same manner, the air is compressed and stored in a tank called as storage tank and when the air is released into an engine, it expands and pushes the piston and turn the crankshaft. This was first developed by a French company, Motor Development International (MDI). This vehicles are also called as Compressed Air Vehicles (CAV).
Compressed Air Vehicles:
The vehicles which runs on compressed air as energy source instead of using fossil fuels. Here in the place of burning the air fuel mixture to push the pistons by the action of hot gases, this vehicles uses the expansion of the compressed air to push the pistons. The compressed air is stored in storage tanks. In addition to compressed air if any other power source (petrol, diesel, electric system with regenerative braking) is used those are known as hybrids.

3. PAGE 2
Main Parts:
 Air Storage Tank
 Air Engine
 Compressed Air
Air Storage Tank:
The tanks should satisfy the safety standards of a pressure vessel, ISO 11439. It can be made of metals or any other materials. The metal tanks suits good but should be checked for corrosion. The tanks can be filled at the stations as well as at home. It takes nearly 4 hours to fill the tank at home using ordinary equipment. But, can be filled in less than 4 minutes at air filling stations. The one drawback in filling the air in less time is there are chances for the tank to get melted off. Normally, the temperature of the compressed air will be high. So, filling the tank with gradual cooling is required. There are tanks that stores the air at 30 MPa. The tanks must be non-flammable, free of high-impact crashes. For this Carbon-Fiber tanks suits best. But economically expensive. The air tanks in air powered cars are composed of an interior thermoplastic container which ensures it is airtight

4. PAGE 3
METAL TANK CARBON FIBER TANK
Air Engine Technology:
Here in Compressed Air Vehicles, air engine which uses compressed air as fuel is used. Most of these engines uses one or more expander pistons or rotary expanders. It is necessary to heat the air or the engine during expansion. Once compressed air is slowly released, it powers the piston. The engine converts this air power to mechanical power and rotates the wheels. Pneumatic cylinders and pneumatic solenoid valves are used in this engines. Pneumatic cylinders produce a force when powered with compressed air. They converts the potential energy of compressed air into the kinetic energy by expanding the compressed air. Pneumatic solenoid, here it is used to convert energy to motion. It is an electric device which acts as a switch in controlling the flow of air or water. Just like normal switches it also stays open when current passes and stays closed when current is blocked. It refers to change of state. Pneumatic solenoids contains an internally driven pilot valve with two inputs as compressed air, two inputs to actuate the pilot (electric), and one exit. Generally 5/2 & 5/3 valves are used in operating double acting cylinders. Similar to the diesel engine it also works under constant volume cycle. The only difference is at the end of compression stroke, high pressure air at ambient temperature is injected into the cylinder. It is done by electro mechanical injection system. When the compressed air (hot) mixes with the injected high pressure cool air, the mixture tries to attain equilibrium temperature, expansion takes place. The high pressure inside the cylinder will impart high force on the piston head. This runs the engine. Hence it is an expansion process and no combustion takes place in this process. This results in zero emissions. The cost of engine is low. Since, no need of designing the cooling system, sparkplugs etc., for compressed air engine (CAE). It is a low weight engine.

5. PAGE 4
Compressed Air:
The air which is treated with high pressures than the atmospheric air pressure is known as compressed air. Energy density of compressed air is low when compared to lead-acid battery, lithium-ion battery, gasoline. But the compressed air can gain more than double the energy density when air is heated followed by expansion. Usage of gases which can be liquefied can increase the energy density.
Energy Source
Energy Density
Compressed Air
50 Wh/Ltr
Lead-acid Battery
60-75 Wh/ltr
Lithium-Ion battery
250-620 Wh/ltr
Gasoline
9411 Wh/ltr
Emissions:
Unlike combustion engine vehicles, air powered vehicles exhausts the air. No pollutants will be present in the exhausted air. The air gets filtered before entering the cylinder. So, less chances of presence of dust in the exhaust air. Hence air powered vehicles can also be called as zero emission vehicles. These vehicles can helps us in reducing pollution in the atmosphere.

6. PAGE 5
How CAV’s are developing:
 First air car made its entry in to public was made by Motor Development International (MDI) in the year of 2002. But, the cars never undergone production as per January 2009. The best innovation of MDI was the active chamber where the air is heated in order to double the power output.
 Association of Promotion of Usages of Quasiturbine (APUQ), a French Company made an air car powered by a Quasiturbine.
 Tata Motors of India in collaboration with MDI planned to launch an air powered car in 2011. But due to low engine temperature problems research is still going on.
 An Australian company, Engineair builds small vehicles which uses air engine of their own design.
 Honda exhibited its air concept car at the LA Auto Show in the year of 2010.
 Peugeot announced that they are building an air powered hybrid car that uses compressed air and gasoline (it runs car over 70 km/h) as energy source. The new 2008 model has a capability of running solely on air, gasoline or both.
 In 2011, Toyota developed an air powered three-wheeler named as “Ku:Rin”. It registered a top speed of 129.2 kmph even when runs by compressed air only. Peugeot Hybrid Car and its system at Geneva Motor Show 2013

7. PAGE 6
V
MDI Air Car The Victor Tatin
Advantages:
 Unlike gasoline engines, it uses compressed air as fuel (air is natural and cheaply available).
 Refuelling can be done at home. It takes 4 hours at home. But with special equipment it can be done in 3 minutes at filling stations.
 Cost of production is relatively low because we need not to use engine cooling system, sparkplug, and starter motor.
 Air powered cars are less in weight.
 Reduction or elimination in harmful chemicals in exhaust gases.
 Another interesting feature is the pneumatic system. When the car brakes, the kinetic energy from braking is used to drive a pump that helps to restore some of the lost pressure.
 As compressed air is not combustible as the other fuels, so it’s safe to carry a compressed air tank.
Disadvantages:
 Low power is produced.
 High speeds are not possible.
 The temperature of air increases when it is compressed to high pressures. This heats the tanks. So the air is to be cooled while filling the tank or the tank has to be provided with a heat exchanger.

8. PAGE 7
Image showing the MDI Air Pod refuelling at a fuelling station.
Image showing the MDI Air Pod refuelling at home.

9. PAGE 8
Tata-MDI joint project
Future Possible Improvements:
At present research is going on the air powered cylindered engines. A French company, APUQ has already developed an air car using Quasiturbine. In the same manner, CAV’s can make use of “TESLA TURBINE”. Tesla designed and manufactured his first bladeless turbine in the year of 1913. It runs on any viscous fluid. It also runs on Compressed Air. Tesla designed his turbine to replace the combustion engines. But by the time he developed this engine, the piston technology had taken the lead in the automobile industry and Parsons and Curtis turbines in steam power plants. His model did not fit into profit plans of that day. But in the last1960’s to early 1970’s Tesla Turbine got researchers eye on it. In the present world it can contribute to reduce pollution.

10. PAGE 9
Working of Tesla Turbine:
It is a bladeless turbine which uses rotary discs for the shaft rotation. It is also known as “Boundary Layer”. Unlike conventional turbines, Tesla turbine consists of a set of discs separated by washers mounted on a shaft. A jet of compressed air is injected into the turbine using a nozzle. The fluid uses its viscous properties which are more dominant in the boundary layer region and rotates the discs. The fluid takes spiral path over the disc surface and leaves the turbine axially through the holes provided around the shaft. The discs rotate the shaft and hence the energy is generated. The drawback of this turbine is that it is a low torque and high rpm turbine. If the shaft is connected to a special equipment which increases the output torque of the turbine, it can be used as an engine in automobiles. Till date all engines used piston technology. If proper research is done it can be installed as engine in locomotives.
Conclusion:
Compressed Air Vehicles are comparatively light weight, low cost, and zero emission vehicles. So automobile manufacturers are showing interest in CAV’s. The concept is not new it’s been lasting from years. By using CAV’s we can reduce the pollution in atmosphere. These cars very helpful in the future for the means of transportation.
References:
 Wikipedia- Compressed Air Vehicle & Compressed Air Car.
 Study and Fabrication of Compressed Air Engine, Paper by JP Yadav and Bharat Raj Singh.
 Images from google images.
 A Compressed Air Vehicle, PPT by Manish Kumar.
 AIR POWERED VEHICLES, PPT by anonymous.