Diesel Particulate Filter

How The Diesel Particulate Filter (DPF) Works? Explained

 | 5 minutes read

 What is Diesel Particulate Filter (DPF)?

The NOx & particulate emission from diesel engines is a greater threat to the environment. To reduce its impact, automotive engineers developed DPF to conform to the stricter Euro-6 emission standard. The term DPF stands for Diesel Particulate Filter. It is used in the diesel engine that is Euro-6 emission compliant. The manufacturers use the Diesel Particulate Filter to filter, store and burn the soot particles which are emitted as a result of the combustion process of the diesel.

Diesel Particulate Filter construction
Diesel Particulate Filter construction

Generally, the oxidation catalytic converter and Diesel Particulate Filter come in a common cylindrical unit. Diesel Particulate Filter consists of silicon carbide. It can filter about 99% of solid particulate matter from the exhaust of a diesel engine. The soot particles or the carbon particles deposited on the filter channels are oxidized into carbon dioxide (CO2) at exhaust temperatures above 600oC. The basic Diesel Particulate Filters are the single-use type. You need to dispose and replace them when they get full after accumulating the ash. More advanced design can also burn off the accumulated soot by using a catalyst.

What are Particulates?

Particulates are the form of carbon that accumulates in the exhaust system of a car’s engine. The particulates originate from various leftovers which depend upon what type they are. In the terms of vehicles, the particulates are the minute solid particles of exhaust gases which an engine emits. The engine emits these particulates mainly in the form of carbon or soot.

You can find this type of carbon particulates mostly in the vehicles that operate on diesel engines. Because of the high compression ratio of the diesel engine, the exhaust coming out from the diesel engines contains the carbon particulates with high density and of bigger size.

Thus, the particulate matter forms a layer of the carbon inside the exhaust system of the engine. This is the main reason why taking care of the exhaust system of the engine is very important. So, it is necessary to limit the quality of carbon particulates emitting to prevent the problems of the environment. Some of the countries have very strict rules about the emission of the engine smoke that can cause the problem to the environment as well as people living in that countries. It is the Environment Protection Agency (EPA) which governs the emission rules in the USA.

How does a Diesel Particulate Filter work?

The unfiltered exhaust flows thru’ the DPF’s channels that are open at the inlet end. The Diesel Particulate Filter core contains porous walls of a ceramic honeycomb structure made of silicon carbide. The exhaust gases then enter into the channels that are open at the outlet end. Furthermore, the exhaust systems take away the exhaust gases. The DPF core retains the soot particles physically. It later burns them off during the regeneration phase. The CDI control unit computes the amount of soot and ash accumulation in the Diesel Particulate Filter with the help of DPF differential pressure sensor.

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