Reduction of diesel emissions
EGR Exhaust gas recirculation
The EGR valve helps your car more efficiently and completely burn fuel by recirculating a portion of your exhaust and running it through the combustion process again. This results in a cooler, more complete burn of the fuel which decreases you car's noxious emissions by prohibiting the formation of some harmful gases.
The EGR valve will not always operate. It will only operate when cruising and at a constant speed not when accelerating
Pros
The EGR valve is vital to your car's emission controls. Exhaust gas recirculation helps to keep huge amounts of unburned fuel from being released into the atmosphere. This unburned fuel is thought to be a huge contributor to greenhouse gas build-up. That's why an EGR system became mandatory on all new vehicles some time ago.
Cons
When the EGR valve goes bad, it must be replaced. Unlike some emissions control devices that can go bad without affecting the drivability of the car or truck, a bad EGR valve can really affect the engine's performance, or even cause it to stop running altogether. The good news is you can clean it.
Catalytic converter ďƒ˜ The core is usually made for a ceramic monolith with a honeycomb structure. Metallic monolith made of kanthal are used in cases where high heat resistance is required. ďƒ˜ There are two different types of cats two ways and three way. A two way converter reduces the amount of carbon dioxide and carbon monoxide, whereas a three way will also reduce the amount of oxides of nitrate.
DPF (diesel particulate filter) ď ľ
Diesel particulate filters are used to reduce the amount of particulates that come out of the exhaust and these can only be found on diesel engines. Particulates can cause smog in the air witch can harm the ozone layer. So if your ever sat behind a diesel engine and you see that typical black smoke come out the back then this is what that normally is, well that and some unburnt fuel.
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These are usually found before the catalytic converter as otherwise it will destroy the cat quicker
Regeneration ď ľ
Regeneration is the process of removing the accumulated soot from the filter. This is done either passively from the engine's exhaust heat in normal operation or by adding a catalyst to the filter or actively introducing very high heat into the exhaust system. On-board active filter management can use a variety of strategies.
Glow plugs Starting When a pre-set time has elapsed, the glow plug relay switches off the "wait-to-start" light. A pre-heating cycle usually lasts for 2 to 5 seconds. The operator then proceeds to turn the key to the "start" position. The relay switches off the glow plugs after the engine is running (or, in older cars, at the same time the "wait to start" light goes out). In some cars, glow plugs continue to operate for up to 180 seconds after engine start to keep the engine within emissions regulations, as combustion efficiency is greatly reduced when the engine is very cold. ď ľ
The high pressure and spray pattern of the diesel ensures a controlled, complete burn. The piston rises, compressing the air in the cylinder; this causes the air's temperature to rise. By the time the piston reaches the top of its travel path, the temperature in the cylinder is very high. The fuel mist is then sprayed into the cylinder; it instantly combusts, forcing the piston downwards, thus generating power. The pressure required to heat the air to that temperature, however, necessitates the use of a large and very strong engine block.