Jälkipuhdistus

Jälkipuhdistus, also known as aftertreatment, is a process used in internal combustion engines to reduce the emissions of harmful pollutants. It typically involves the use of catalytic converters, which convert toxic gases such as carbon monoxide, nitrogen oxides, and hydrocarbons into less harmful substances like carbon dioxide, nitrogen, and water vapor. This process is crucial in meeting environmental regulations and improving air quality.

The most common type of aftertreatment system is the three-way catalytic converter, which is used in gasoline engines. This system operates most efficiently when the engine is running at a stoichiometric air-fuel ratio, meaning the air and fuel are mixed in the exact proportions required for complete combustion. However, modern engines often use lean-burn technology, which runs the engine with excess air to improve fuel efficiency. In such cases, a different type of aftertreatment system, such as a selective catalytic reduction (SCR) system, may be used to reduce nitrogen oxide emissions.

Aftertreatment systems can also include other components such as particulate filters to capture and trap soot particles from diesel engines. These filters require periodic regeneration to burn off the accumulated soot, which can be done by increasing the engine's exhaust temperature or using a fuel-based regeneration system.

The effectiveness of aftertreatment systems can be influenced by various factors, including the engine's operating conditions, the quality of the fuel, and the maintenance of the aftertreatment components. Regular maintenance and proper use of the engine are essential to ensure that the aftertreatment system operates at its best and contributes to reducing harmful emissions.