The year 2020 marked the 50th anniversary of the passage of the Clean Air Act in the United States. The subsequent creation of the Environmental Protection Agency (EPA) and establishment of national ambient air quality standards (NAAQS) for criteria air pollutants paved the way for increasingly stringent tailpipe emission limits for passenger cars and trucks. These limits have been met through significant advances in both engine hardware and controls, and after-treatment systems, the latter of which will be the focus of this chapter. Modern powertrains using advanced after-treatment systems can practically eliminate the harmful gases and particulates from entering the atmosphere. Three-way catalysts (TWC) can address NOx, CO and hydrocarbons (HC) emissions from stoichiometric gasoline vehicles with near 100% efficiency when operating above the light-off temperatures. Diesel vehicles, despite the bad press in recent years, can be emitting well below the regulated limits with the adoption of the latest technologies such as selective catalytic reduction of NOx (SCR). The key challenge in both technologies is addressing the “cold-start” emissions, which is the combination of high emissions following an engine start and after-treatment temperatures below light-off. We will review the latest options that are being pursued to address this challenge and lead to “zero-impact” emitting vehicles. Particulate filters are ubiquitous on diesel vehicles and are also making their way on to gasoline vehicles with the recent particle number regulations in Europe and China. Filtration efficiency is very high and only improves with vehicle age due to the accumulated ash layer. There is evidence that in highly polluted urban environments, the tailpipe particulate emissions can in fact be lower than the ambient concentrations. Emissions control technology is mature but still there is much more work to be done. New regulations such as Euro 7, LEV 4 and the heavy-duty low NOx regulations in US and Europe are looking for further deep cuts in pollutant limits, regulating new species and particulates down to 10 nm, and extending the testing to include “all” driving conditions. We will review the new component technologies and the after-treatment system layouts being developed to address these upcoming regulations.


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    Titel :

    A Review of Emissions Control Technologies for On-Road Vehicles


    Weitere Titelangaben:

    Energy, Environment, and Sustainability


    Beteiligte:
    Kalghatgi, Gautam (Herausgeber:in) / Agarwal, Avinash Kumar (Herausgeber:in) / Leach, Felix (Herausgeber:in) / Senecal, Kelly (Herausgeber:in) / Joshi, Ameya (Autor:in)


    Erscheinungsdatum :

    2021-12-14


    Format / Umfang :

    18 pages





    Medientyp :

    Aufsatz/Kapitel (Buch)


    Format :

    Elektronische Ressource


    Sprache :

    Englisch




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