This content is not included in your SAE MOBILUS subscription, or you are not logged in.
Automobile Exhaust Emmision Control- A review
ISSN: 0148-7191, e-ISSN: 2688-3627
To be published on November 21, 2019 by SAE International in United States
Event: NuGen Summit
Since the 20th century increase in the number of cars in the major cities is been a point of concern because of the toxic gasses being emitted from the engine of an automobile. These gasses are polluting the atmosphere and degrading the air to breathe. The main gasses responsible for the degradation of air quality are carbon monoxide, hydrocarbon and oxides of nitrogen. There is a necessity to find ways to reduce the pollution emitted into the atmosphere from the automobile. The source of emission is either evaporation from fuel tank or carburetor which is easy to be dealt with or harmful gasses due to improper combustion which is a concern for the environment. The two ways to reduce these emissions are, modification in the engine to minimize the production of harmful gases and to treat the harmful gasses emitted from the engine before blowing it into the atmosphere from the exhaust. Catalysts help to break harmful gasses into smaller compounds that are environment-friendly. The catalysts used are Rhodium Palladium and platinum, these make a unit called catalytic converter. The catalytic converter reduces the oxides of nitrogen into N2 and O2 and converts HC + CO into H2, H2O and CO2. Now conversion of all the catalyst can be done over a single three-way catalyst, which is possible when the composition of the exhaust is close to stoichiometric. Fuel efficiency was being compromised in the three-way catalyst converter and to get diesel engines with better fuel efficiency and lean burnt mixture there was a rise in interest. Reduction of HC and CO is still the same but reducing oxides of nitrogen is practically not possible under lean condition. Now different new approaches are being researched for lean oxides of nitrogen that are lean oxides of nitrogen trapping catalysts and Selective catalytic reduction these areas still have some loopholes which are being discussed in the study and various ideas for solving the problems regarding lean NOx.