Exhaust gas after treatment
A DPF captures and removes exhaust soot (also known as particulate matter or pm) from diesel exhaust emissions. Pm is made up of tiny particles of soot Carbon, and other materials that can cause health problems and air pollution. The DPF works by trapping the PM in its honeycomb filter, which is made up of a porous material that allows exhaust gases to pass through but traps the PM. The DPF periodically needs to be cleaned to remove the accumulated PM this is done either through a certain driving style mainly driving the vehicle for a long distance at high revs per minute or a process called forced regeneration or by replacing the filter.
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Selective Catalytic Reduction (SCR) System: The SCR system is designed to reduce nitrogen oxides (NOx) and is considered active emission control technology. It reduces the NOx by injecting a 32% solution of synthetically manufactured urea and demineralized water called Ad Blue into the exhaust stream and this causes a chemical reaction. The SCR system consists of a catalyst, a dosing system like the Ad-blue tank, pipes, an injector, and a control unit. The catalyst is typically made up of a ceramic material that is coated with a layer of catalytic material, such as platinum, that helps convert NOx into nitrogen (N2) and water vapor (H2O). The dosing system injects Ad Blue into the exhaust stream onto a mixer plate, and the control unit monitors the system's performance.
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Diesel Oxidation Catalyst (DOC): A DOC is used to oxidize carbon monoxide (CO) and hydrocarbons (HC) to convert them into carbon dioxide (CO2) and water (H2O). The DOC is typically made up of a ceramic or metallic substrate that is coated with a layer of catalytic material, such as platinum, that helps convert the CO and HC. The DOC does not reduce NOx emissions.
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Exhaust Gas Recirculation (EGR) System: An EGR system recirculates a portion of exhaust gases back into the engine's combustion chamber to reduce NOx emissions. The EGR system works by diverting some of the exhaust gases from the exhaust manifold back into the engine's intake manifold. The recirculated exhaust gases displace some of the oxygen in the combustion chamber, which lowers the combustion temperature and reduces NOx emissions.
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Diesel Exhaust Fluid (DEF): DEF is a urea-based solution that is used in the SCR system to help reduce NOx emissions. DEF is injected into the exhaust stream, where it reacts with the SCR catalyst to convert NOx into nitrogen (N2) and water vapor (H2O). DEF is stored in a separate tank on the vehicle and needs to be periodically refilled.
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Exhaust Gas Recirculation (EGR) System: An EGR system recirculates a portion of exhaust gases back into the engine's combustion The EGR system works by diverting some of the exhaust gases from the exhaust manifold back into the engine's intake manifold. The recirculated exhaust gases displace some of the oxygen in the combustion chamber, which lowers the combustion temperature and reduces NOx emissions.
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Diesel Exhaust Fluid (DEF): DEF is a urea-based solution that is used in the SCR system to help reduce NOx emissions. DEF is injected into the exhaust stream, where it reacts with the SCR catalyst to convert NOx into nitrogen (N2) and water vapor (H2O). DEF is stored in a separate tank on the vehicle and needs to be periodically refilled.
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Catalytic Converter: A catalytic converter is a device that converts toxic gases and pollutants in the exhaust gas stream into less harmful substances. The catalytic converter typically consists of a ceramic or metallic substrate that is coated with a layer of catalytic material, such as platinum, that helps convert the pollutants. The catalytic converter can help reduce emissions of CO, HC, and NOx.
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Exhaust Gas Temperature (EGT) Sensor: An EGT sensor measures the temperature of exhaust gases to ensure that the after-treatment system is functioning properly. The EGT sensor can detect if the system is overheating, which can damage the after-treatment components and lead to increased emissions.
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Exhaust Gas Pressure (EGP) Sensor: An EGP sensor measures the pressure of exhaust gases to ensure that the after-treatment system is functioning properly. The EGP sensor can detect if there is a blockage in the exhaust system, which can lead to increased emissions and decreased engine performance.
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