- March 18, 2013
- Posted by: essay
- Category: Term paper writing
Car exhaust fumes present a major cause of the air pollution, especially this environmental problem is acute in large cities, where there are millions of cars. Consequently, an important task in modern automotive engines is the control of combustion of gasoline. To solve these problems each country has its own laws, which limit the possible level of pollution. Since that time, automakers have made many improvements in the design of automotive engine and fuel systems to meet these requirements. One of the significant changes happened in 1975, when was made a new device called a catalytic converter, or simply a catalyst. The purpose of the catalytic converter is to convert harmful exhaust gases into less harmful before they go from the exhaust system of the car into the atmosphere. (www.epa.gov.)
In order to reduce emissions in modern car engines is carefully controled the amount of fuel burned. The main pollutants produced by the engine are:
– Nitrogen gas (N2): their consists of the nitrogen gas on 78 per cent, and most of it passes through the car engine.
– Carbon dioxide (CO2) which is one of the products of combustion, when carbon from the fuel combines with oxygen of air.
– Water vapor (H2O) – another product of combustion. Hydrogen from the fuel combines with oxygen of air. (Miller et al., 2008)
Basically, these products of combustion are not dangerous, but it is known that the problem of global warming associated with increased production of carbon dioxide in the atmosphere. But since the combustion process is never perfect, the engine car produces a small amount of much more harmful exhaust gases; and to decrease their number was made a simple device that has great significance for ensuring clean air – the catalytic converter. It is aimed at reducing:
– Carbon monoxide (CO) – a poisonous gas without color and odor;
– hydrocarbons (also known as volatile organic compounds) which are the main components of smog;
– nitrogen oxides (NO and NO2, which are often combined under the designation NOx) which are also a component of smog and acid rain, and have an effect on human mucous membranes. (Forman 2003)
Catalytic converter is one of the main elements of the exhaust system of modern vehicles, which provides cleaning of the emission and lowers their noise. Three-way catalytic converters are known from the 80th years of XX century, and provide neutralization of the three main components of emissions: carbon monoxide CO, hydrocarbons HCs, nitrogen oxides NOx. (www.sciencedaily.com)
Modern three-way catalytic converters has a monolithic ceramic or metal (typically, Al2O3) support, coated with catalytically active layer. Thus, the catalytic converter significantly reduces the level of pollution from vehicles, since the machine exhaust gases are converted into less harmful gases in it. (Forman 2003)
In conclusion it is necessary to note that air pollution is one of the hot problems of nowadays, as a part of global ecological problems. Many countries nowadays take efforts to fight with air pollution and have introduced environmental laws that require the use of catalytic converters to reduce smog and other forms of vehicular pollution. Their value can not be large enough to completely solve modern ecological problem, but still it is a step towards solving the problem of air pollution.
“Catalytic converter”. www.sciencedaily.com. Web. 9 May 2011
Forman Richard T. Road ecology: science and solutions. Island Press, 2003
Sun N. “The Catalytic Converter”. scienceray.com. Web. 9 May 2011
Tao Huai, Thomas D. Durbin, J. Wayne Miller, John T. Pisano, Claudia G. Sauer, Sam H. Rhee, and Joseph M. Norbeck. Investigation of the formation of NH3 emissions as a function of vehicle load and operating condition. www.epa.gov. Web. 9 May 2011
Miller George T., Spoolman Scott E. Essentials of Ecology. Cengage Learning, 2008