The Compressed Air Vehicles
This type of vehicle unlike many others runs not on fuel but on a working fluid, which is air. It is powered by an air engine using compressed air stored in a pressurized tank. No combustion takes place in its operation; the expansion of compressed air is what drives its piston. Its engine could produce a high efficiency with almost zero exhaust and no fuel hazard.
Engine Operation and Mechanism
Although compressible as a fluid, air could exert tremendous force, as what is shown when it is applied in pneumatic cylinders. In the case of automobile applications, the principle is the same as in pneumatics; work is created by the expansion of compressed air. This is accomplished by first storing air in tanks at high pressure such as 30 Mpa (4500 psi or 300 bar). Tanks are constructed with light weight materials such as carbon fibers. The vehicle utilizes no fuel and air is used as a working substance instead with no combustion taking place. It should be noted that compressed air engines are already in used in tools, torpedoes and railways. In automobiles, the expanding air released from tanks then moves the pistons which the drives engine. Typical air engines use one or more expander pistons. This makes the compressed air engines literally a pneumatic actuator that drives a vehicle.
At present there are several variations in air engine design. Some uses an alternator to improve the running time of the engine. There are also those that use rotary engine designs. And to make the engine more efficient, air is then heated; one manufacturer even claims achieving ninety percent efficiency.
The vehicle produces very little exhaust with impurities coming mostly form residues of the engine lubricants. And emission source is displaced from the vehicles tail pipe to the central electrical generating plant; the engine itself runs on its exhaust. Air used in the engine is filtered from dust to protect the compressor machinery. The air discharged has less dust suspended in it.
Advantages and Disadvantages over other Vehicles
This is in the case of automobile applications only and not in other compressed air vehicles. Where since the need for a combustion system and cooling system is eliminated, vehicle cost is cut by 20%. And air is non flammable, eliminating fire hazard on vehicles. Air could also produce a very high torque for minimum volume and design for the engine is simple and robust. The manufacturing cost is low and the vehicle is easy to maintain and used tanks could be recycled with less pollution unlike batteries. Compressed air tanks also won’t degrade, a problem with battery use, easy to refill with air and the vehicle itself is a lot lighter. Fueling price is also cheaper.
Compressed air technology also shows weaknesses in some areas. Although engines are simple and robust, it is still not robust enough unlike many vehicles. And problems could occur when it is used in cold weathers.