Diesel emission control system are engineered to reduce harmful pollutants such NoX Nitrous Oxide and Diesel Particulate Matter from exhaust gas which is harmful to the environment.
This emission control system work using the EGR,DPF,DPF Re-Gen, DEF and SCR.
Lets take look at this one by one.
01. EGR(Exhaust Gas Recirculation) – The exhaust gas is re-circulated in to the engine air intake to reduce the Nox emission. The exhaust gas is sent to the EGR cooler where the temperature is reduced and travels through the EGR valve and passes into intake manifold which reduces the formation of nitrogen oxides (NOx).
Limitations:
This process consumes more fuel, decreases the engine power and increases DPM emission.
The DPM(soot) gets into the engine oil and turns it into harsh which increases the wear and tear of the engine components which leads to reduced engine life time.
02. DPF(Diesel Partculate Filter) – Diesel Partculate Filter is used which reduces the DPM(soot). The exhaust gas is re-circulated in to the engine air intake via DPF filter which reduce the Nox emission and DPM(soot). Then exhaust gas is sent to the EGR cooler where the temperature is reduced and travels through the EGR valve and passes into intake manifold which reduces the formation of nitrogen oxides (NOx).
Limitations:
This process consumes more fuel, decreases the engine power and increases DPM emission.
The DPM(soot) gets into the engine oil and turns it into harsh which increases the wear and tear of the engine components which leads to reduced engine life time.
03.DPF – Re-Gen(Regeneration) – This process is used to burns the accumulated soot by raisingtemperature to 1100’C inside the DPF filter. The manufacturer design the periodic re-generation cycle process for the DPF filter and it gets activated based on the engine operational mode.
Example: if the DPF regeneration process happens at or above 80KMPH, the user should maintain the same speed for certain duration(mentioned by the manufacturer) inorder to complete the DPF regeneration process.
DPF – Re-Gen(Regeneration) can be made in two ways,
Passive Regeneration – Happens naturally when driving at highway speeds.
Active Regeneration – Initiated by the engine control unit (ECU) by injecting extra fuel to raise exhaust temp.
Limitations:
01. Irregular DPF regeneration process leads to clogging the DPF filter that is if the driving mode is changed intermediately during the burning cycle then it leads to DPF filter clogging.
02. Decreased engine efficiency.
04. DEF & SCR – DEF Diesel exhaust fluid is a liquid(urea) consists of ammonia and SCR Selective Catalytic Reduction works together to reduce the NoX emission.
When engine reaches certain operational condition the ECU send the signal to inject the DEF fluid into catalytic chamber, during the process ammonia mixes with NOx and it is converted into water & nitrogen(H2o & N2).
Limitations:
01. If the DEF fluid is in-sufficient, then the engine goes to emergency mode(ECO) and speed is dropped based on the manufacturer setting. The DEF fluid need to be added to resolve the issue.
02. If the DEF fluid is not re-filled in a timely manner/temperature drops, the remaining urea may get frozen, in this case the engine will not start untill the problem is fixed.