Pollution controlling devices in Automobiles
Automobiles emit more than half of all carbon monoxide and hydrocarbons in the environment. These emissions include microscopic particles that might cause breathing trouble and heart problems. That is what makes it imperative to have an emission control system in automobiles that can at least reduce the emission of toxic gases from combustion engines and other components of a vehicle.
According to the Environmental Protection Agency report, vehicles are responsible for causing 75% of carbon monoxide pollution. The on-road vehicles cause one-third of the air pollution that converts into smog.
Some of the major pollutants emitting from the cars are:
● Carbon monoxide: Vehicles emit carbon monoxide if the carbon in fuel is partially burned.
● Hydrocarbons: The exhaust of vehicles emits a toxic compound, hydrocarbons.
● Nitrogen oxides: Nitrogen and oxygen react with each other when the fuel is burned and forms Nitrogen oxides.
● Particulate matter: This is one of the major pollutants that cause respiratory troubles in living beings. These are the small particles in the air that causes the atmospheric haze and reduces visibility.
Apart from all these pollutants, it is a well-known fact that vehicular emission increases carbon dioxide and greenhouse gas levels.
The emission takes place from namely three sources:
● The engine exhaust: Exhaust pipe emits completely or partially burned carbon monoxide, hydrocarbons, oxides of sulfur and nitrogen, traces of alcohols, phenols, and acids.
● The crankcase: It is a source of unburned hydrocarbons and a little amount of carbon monoxide too.
● The fuel tank and carburetor: It constantly evaporates hydrocarbons from gasoline in a small but significant quantity.
But gone are days to fret over these issues as technological advancement has brought about a number of systems for controlling emissions from various sources.
Positive crankcase ventilation valve (PCP): Leaked combustion gases in the crankshaft are added with ventilating air and brought back to the intake manifold to burn again in the combustion chamber.
Exhaust gas recirculation system (EGR): Exhaust emissions are responsible for about two-thirds of the total pollutant coming out of the engine. In the EGR system, exhaust gases are directed towards the cylinder head to combine them with the fuel-air mixture before entering the combustion chamber. This recirculated gas favors the slower production of nitrogen oxides as the product of combustion.
Air-injection system: In this system, the air is injected into the exhaust by an engine-driven pump from where it combines with partially burned hydrocarbons and carbon monoxide. The temperature is kept high in order to continue the combustion process. This burns a significant amount of pollutants discharged through the exhaust system.
Catalytic converter: This performs combustion in an insulated chamber consisting of ceramic pellets or a ceramic honeycomb structure. It is coated with a thin layer of platinum and palladium. When the exhaust fumes are passed via honeycomb, the platinum and palladium metal act as catalysts to convert the hydrocarbons, carbon monoxide, and nitrogen oxides to water vapor, carbon dioxide, and nitrogen, respectively.
Evaporative control system: Earlier gasoline fumes were evaporated into the atmosphere, but now the emissions are reduced to a large extent by sealed fuel tank caps called evaporative control systems. It has a vacuum separator that draws the vapors to the canister via a filter and finally to the combustion chamber, where it is completely burned.
Conclusion
The world is in dire need of more such technological advancements that can reduce the extent of vehicular pollution. Since automobiles are becoming an indispensable need of humankind, it becomes our responsibility to let the emission control systems go hand in hand with the increasing pollution in order to maintain a balance in the environment.
Meta Description
Automobile emission is not new. What is new is the various emission controlling systems like catalytic converters & PCP valves that you must be well -aware of.
References
https://www.britannica.com/technology/emission-control-system
https://auto.howstuffworks.com/air-pollution-from-cars.htm
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