1. Diesel Particulate Filter (DPF):
- Diesel engines primarily emit soot particles or particulate matter (PM). A DPF is a ceramic filter installed in the exhaust system that captures and traps these PM emissions. As the exhaust gases pass through the filter, the particulate matter is trapped and gradually accumulates in the DPF.
- When the DPF becomes loaded with soot, a process called regeneration occurs to remove the accumulated particles and clean the filter. Regeneration typically takes place by actively increasing the exhaust temperature, either through fuel injection methods or an additional oxidation catalyst, burning off the trapped PM.
2. Selective Catalytic Reduction (SCR) System:
- SCR is a technology used to further reduce nitrogen oxide (NOx) emissions in diesel engines. An SCR system consists of a catalyst and an aqueous urea solution (urea injection) that is sprayed into the exhaust stream upstream of the catalyst.
- The urea decomposes into ammonia (NH3) when it comes into contact with the high-temperature exhaust gases. The ammonia then reacts with NOx in the presence of the SCR catalyst, converting them into harmless nitrogen (N2) and water (H2O).
Unlike catalytic converters used in gasoline vehicles, diesel particulate filters and selective catalytic reduction systems focus specifically on reducing soot and nitrogen oxides from diesel engine emissions, meeting stringent emission standards and regulations for diesel vehicles.
