Derv car also need not add urea.
Above all in engine flaming process, the grain that the platoon gives off (for instance PM2.5) with NOx (azotic oxygen compound) can cause very big pollution to the environment, so these a few years discharge code to these (still have a hydrocarbon) the requirement is stricter and stricter.
And theoretic grain content follows NO is contradiction, you want me to exert all one's strength combustion does not discharge grain, next high temperature oxygen boosting produces NO easily; Drop in temperature step-down falls NO, grain is discharged tall, and this kind of phenomenon is particularly apparent on diesel engine.
Have two solutions so:
It is to pass EGR (exhaust recycle) drop combustion temperature, reduce NO to discharge, use DPF next (grain is caught implement) the grain thing that purify adds, this kind does not need to add urea.
The foreign matter of benzine combustion eduction is less than diesel engine, can use 3 yuan of catalysis implement, diesel engine uses 3 yuan of catalysis implement block up easily.
2 it is to optimize combustion efficiency (raise temperature, pressure boost for instance) will burn grain content, use SCR next (alternative catalysis is reductive technology) reduce NO to discharge, optimize combustion efficiency to mean more the province is oily, so domestic cart uses the technology from the back for the most part, this needs to add urea regularly.
