CNG VEHICLE: ENVIRONMENT AS WELL AS WALLET FRIENDLY
CNG is an acronym used for COMPRESSED NATURAL GAS. It is one of the most practical as well as viable alternative to fossil fuels. Although CNG powered vehicles emits greenhouse gases, it is more environmental friendly and safe than the traditional sources of power generation.
BASIC CONSTITUENTS OF CNG KIT
CNG kit fitted in automobiles consists of following parts:
CYLINDER: Its primary purpose is to store CNG. The working pressure is maintained at 200 bars. The cylinder is fitted with shut-off valve & safety burst disc.
VAPOUR BAG: It is mounted on the cylinder & used to connect the cylinder valves & interconnected pipes.
HIGH PRESSURE PIPE: The function of the pipe is to connect refueling valve to the CNG cylinder & pressure regulator.
REFUELLING VALVE: As name suggests, it is used for refueling the CNG.
PRESSURE REGULATOR: It contains the solenoid valve that shuts off the supply to the engine. Pressure regulator reduces the pressure of the CNG just below the atmospheric pressure. This also ensures that the gas does not enter when the engine is in shut off mode.
GAS-AIR MIXER: The work of this component is to meter the amount off gas fed into the engine. It is designed depending upon the capacity of individual engines.
PETROL-SOLENOID VALVE: When the engine is running on gas, this valve cuts-off the supply of petrol to the engine.
SELECTOR SWITCH: It enables the driver to select the mode of operation. Driver can switch between CNG or Petrol mode depending upon the situation.
WORKING OF A CNG VEHICLE
CNG powered vehicle run on the same principle as of the gasoline powered engine. Fuel is mixed with air in the cylinder & ignited to move the piston in order to achieve the useful work. The only difference is in the intrinsic properties of fuel i.e. CNG & Gasoline. The flammability as well as ignition temperature are the key differentiating factors between the two fuels.
Compression ratio difference between two vehicles is another important factor which differentiates the fuel types. In case of gasoline engine, pressure of fuel-air mixture is highest at end of compression stroke. Thus when ignited, it burns rapidly & performance is more than adequate thanks to high calorific value of the fuel. Whilst, in case of a CNG powered engine fuel being in gaseous state, this requires a certain temperature build-up inside the cylinder to create a high pressure situation inside the engine. This is the reason why warming up is required in case of a CNG run vehicles therefore all CNG based engines are first started with gasoline/petrol.
ADVANTAGES OF CNG VEHICLE
Reduced pollution. CNG vehicle can reduce as much as up to 93% reduction in the emission of carbon monoxide, 33% reduction in harmful nitrogen oxides & 50 % reduction in reactive hydrocarbons
CNG costs as less as about 1/3rd of the petrol.
CNG prices are relatively stable when compared to the gasoline prices.
Lower maintenance cost, as the wear & tear of the engine is less as compared to gasoline engines.
CNG tanks are thicker than the petrol or diesel storage tanks, thereby increasing safety proposition.
DISADVANTAGES OF CNG VEHICLE
CNG vehicles are not as roomy as the gasoline engine. The cylinder kit, especially, eats out all the space in the boot. Situation is worse in case of small hatchbacks. Fit CNG and you literally have no boot space left.
Range of CNG powered vehicle is limited. This is the reason why DUAL-POWERED vehicle are more popular rather than only having CNG option.
CNG vehicles are less practical with limited number of refueling stations.
Despite obvious demerits of a CNG vehicle, they are being preferred by most new car buyers in metros where availability is a non-issue thanks to its low running cost.