Exhaust gases released from the engine following combustion of fuel inside the engine chamber are known as emissions. The Environmental Protection Agency (EPA) regulates these emissions from mobile sources by setting standards for the specific pollutants emitted. The EPA has established increasingly stringent emission standards for carbon monoxide, hydrocarbons, nitrogen oxides and particulate matter, beginning in the mid-1970s for road vehicles and in the early 1990s for non-road engines and equipment. These standards set limits on the amount of pollution a vehicle or engine can emit.It is important to note that the goal of engine optimization is not to minimize pollutant emissions from the combustion system or to maximize pollutant reduction in the aftertreatment system (ATS).
Rather, the aim is to achieve a target level of system-wide emissions that is generally sufficiently below the regulatory limit to allow for production variability. This may require an increase in the emission of some pollutants from the combustion system if the performance of the ATS is high enough to meet the design objective.For example, NOx emissions from engines equipped with a urea selective catalytic reduction (SCR) catalyst can be allowed to increase to minimize greenhouse gas (GHG) emissions (due to NOx-brake specific fuel consumption compensation) if high NOx conversion is achieved in the SCR catalyst.Engine emissions are gases and particulates that are expelled by an engine or other mechanical device. Internal combustion engines, such as those used in vehicles, emit emissions from the engine exhaust, fuel tank and the engine itself. Car exhaust gases are composed of carbon dioxide, carbon monoxide, methane and formaldehyde.
The exhaust also contains particles and water vapor. Aircraft engines produce emissions that are similar to other emissions resulting from the combustion of fossil fuels. However, aircraft emissions are unusual, as a significant proportion is emitted at altitude. These emissions give rise to significant environmental concerns regarding their overall impact and their effect on local air quality at ground level.It is an important component of emissions from motor vehicles (and stationary internal combustion engines), which can also include crankcase exhaust and evaporation of unused gasoline.
In the past, International Civil Aviation Organization (ICAO) policy-making to address the environmental impact of aircraft engine emissions focused primarily on ground-level effects. Low emissions over the life of the engine would not be possible unless fuel pollutants, such as sulfur and some inorganic minerals, are controlled at very low levels. Technological advances in vehicle and engine design, along with cleaner, higher-quality fuels, have reduced emissions so much that the EPA expects progress to continue, even as people drive more miles and use more energy equipment each year.This section explains the four main pollutant emissions (CO, HC, PM and NOx) from diesel engines. These systems are especially in-demand for heavy-duty diesel engines, and a combination of diesel oxidation catalyst (DOC), diesel particulate filter (DPF) and SCR has generally been used for simultaneous removal of major pollutant emissions from diesel engine exhaust.
Global emission control legislation is clarified and trends in emission control systems are explained, especially for vehicles with service diesel engines. In-use tests are performed after vehicles or engines have been certified, usually on private-use vehicles or engines.The certificate is a license to produce and sell the vehicle and covers only those vehicles or engines specifically described in the application. Zheng M., Mulenga M. C., Reader G.
T., Wang M., Ting D. S., Tjong J. (200 Biodiesel Engine Performance and Low-Temperature Combustion Emissions). It is vested with the authority to regulate engine emissions, as well as to monitor air quality in general.
In recent years, its scope has been expanded to include global impact of aircraft engine emissions.Particulate matter emissions from diesel engines are significantly higher (six to ten times) than gasoline engines.