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Friday, June 20, 2008

What is NGV ?

NGV stands for Natural Gas Vehicle. They operate similarly to traditional vehicles, but they use natural gas as fuel. Natural gas can power existing cars and trucks by converting the engines to a bi-fuel capability. To convert vehicles to natural gas requires installing a tank, fuel pressure regulators, and fuel lines. Most systems incorporate an electronic module which adjusts the engine to maintain comparable performance levels with either fuel. Limited production of dedicated natural gas engines and vehicles is under way at motor vehicle manufacturers. Refueling stations use the same natural gas as commercial facilities and residences. These stations now provide compressed natural gas for quick-fill.

How a Natural Gas Vehicle Work ?

1. Natural gas is compressed and enters the vehicle through the natural gas fill valve (receptacle).
2. It flows into high-pressure cylinders located in or under the vehicle.
3. In a bi-fuel NGV, a fuel selector on the dashboard permits selection of natural gas or gasoline to act as the fuel for the vehicle. A dedicated NGV operates solely on natural gas.
4. When natural gas is needed by the engine, it leaves the cylinders and passes through the master manual shut-off valve.
5. The gas goes through the high-pressure fuel line and enters the engine compartment.
6. Gas enters the regulator, which reduces pressure from up to 3,600 psi to near atmospheric pressure.
7. The natural gas solenoid valve allows natural gas to pass from the regulator into the gas mixer or natural gas fuel injectors. (Or, it shuts off the natural gas when the engine is not running or when, in the case of a bi-fuel vehicle, gasoline is selected).
8. In a bi-fuel NGV, natural gas mixed with air flows down through the gasoline carburetor or fuel injection system and enters the engine's combustion chambers. In a dedicated NGV, natural gas is injected into the engine's combustion chamber via specially designed natural gas fuel injectors.
9. In a bi-fuel NGV, when the driver selects gasoline, the conventional gasoline system is activated and the natural gas system is automatically shut off.

Why NGV?

Presented below is an outline of the benefits that CNG offers:

Green fuel - Commonly referred to as the green fuel because of its lead and sulphur free character, CNG reduces harmful emissions. Being non-corrosive, it enhances the longevity of spark plugs. Due to the absence of any lead or benzene content in CNG, the lead fouling of spark plugs, and lead or benzene pollution are eliminated.
Increased life of oils - Another practical advantage observed is the increased life of lubricating oils, as CNG does not contaminate and dilute the crankcase oil.
Mixes evenly in air - Being a gaseous fuel CNG mixes in the air easily and evenly.

Safety - CNG is less likely to auto-ignite on hot surfaces, since it has a high auto-ignition temperature (540 degrees entigrade) and a narrow range (5%-15%) of inflammability. It means that if CNG concentration in the air is below 5% or above 15%, it will not burn. This high ignition temperature and limited flammability range makes accidental ignition or combustion very unlikely.
Low operational cost - The operational cost of vehicles running on CNG, as compared to those running on other fuels, is significantly low.At the prevailing price of fuel ,operational cost of CNG vehicles is 68% lower than petrol and 36% lower than diesel.

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