Importance of Exhaust System
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Importance of the Exhaust System in the Auto
Exhaust system of an automobile is an essential system, incorporated to remove exhaust gases from the engine in a manner to reduces the exhaust emissions in the environment. Before studying about the exhaust system components, it is important to learn about the engine scavenging process, which is used to remove the gases from the cylinder.
Scavenging is a process of forcing the exhaust gases to flow out of the engine through the exhaust valves with the help of fresh air that enters during the overlapping period of the valves i.e. period, when both the valves remain partly opened for a short duration. Two-stroke engines and four-stroke engines have different approach to scavenge the exhaust gases. For a four-stroke engine the scavenging air enters at the end of the exhaust stroke and beginning of the intake stroke; whereas for a two-stroke engine, the air is entered during the end of the expansion stroke and during the start of the compression stroke.
We know that the engine produces power by burning the fuel in presence of oxygen. However, while doing the same, the engine also produces some exhaust emissions, such as Carbon Dioxide (CO2), Nitrogen (N2) and Water (H2O). But these less emissions are possible only when a correct amount of fuel mixture is sent to the engine. Theoretically the most correct air fuel ratio is 14.5:1 also known as stoichiometric ratio but in practical, this ratio is hard to achieve due to various factors, like driving habits, engine load, and speed; which causes the engine not to burn the fuel mixture completely and thus developes some unwanted harmful gases in the exhaust. Most common exhaust products include Carbon Monoxide (CO), Hydrocarbons (HC) and Oxides of Nitrogen (NOX). These products are harmful for human beings and give rise to smog and acid rains. The problem of automotive exhaust was realized in early 50s. Different laws were established by the governments of different countries to control the emissions of automotive.Automakers were made to develop a separate exhaust system to save the environment.
Learn How Car Exhaust System Works