Quote:
Originally Posted by me and my metro
The way I understand it is: it is all about controlling NOx emissions. There are two schools of thought, the first is lots of egr to cool the charge. The problem with lots of egr is lots of soot, so you have to trap it and burn it with the cat and extra fuel. The second is not so much egr which makes more NOx but less soot, then kill the NOx with urea. I know International is having trouble meeting the new standards even with urea. I was told our new Internationals will come with Cummins engines because they can meet smog.
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Water + alcohol injection, or eventually CNG fumigation, might make more sense. BTW most of the urea used for DEF production is made out of natural gas, so why not to use CNG directly instead? Either as the primary fuel or integrated with Diesel. A trucking company from Brazil has tested an Euro-3 rated Mercedes-Benz Atego with a dual-fuel setup that could operate with up to 95% CNG, and its emissions were comparable to an Euro-5 rated truck even though it didn't have SCR and DPF.