上汽菲亚特红岩欧四发动机排放系统介绍.ppt

* The PM catalyst system itself consists of platinum oxidation catalyst and metallic catalyst substrates with open cells especially designed for a temporary storage and oxidation of soot. The metallic substrates are made from corrugated foils with small blades and flat foils through which exhaust gas have to pass. So the material inside the PM Cat is thin-walled foil of metal. During the cold start, the catalyst is therefore heated up to the operating temperature correspondingly more quickly so that the conversion begins at an earlier stage of time. The internal structure is designed for a 3D gas mixing process. So it can be described as open structure. So the flow of the exhaust gas is not blocked, but guided. (See graphic). Note. No maintenance is needed, but also a control of the exhaust gas quality (PM) is difficult. No sensor is asked by legislation acts. Note: PM-Kat is the MAN D20 engine solution. * Comparison PM Trap vs. PM Cat The remarkable advantage of a PM Cat compared to a standard PM Trap is caused by the open cell structure and the relatively low level of flow resistance, a selective removal of soot and the effect that ashes from engine lubrication oil are passing. The loss of fuel efficiency compare to a PM Trap seems to be almost avoided. * SCR is an after treatment system that requires Urea as additive, named AdBlue (AdBlue = ammonia plus water). SCR creates a chemical reaction that renders nitrous oxide gases (NOx) harmless. AdBlue is injected into the exhaust. When the mixture passes through the catalytic converter the nitrogen atoms from the NOx bind with those from the ammonia to produce harmless nitrogen gas molecules. The oxygen in the NOx reacts with the hydrogen and produces water. * In the SCR system AdBlue is stored in a specific tank, and injected in a very precise quantity in the exhaust before the catalyst. The injection is made by a dosing module and a metering device under the direct control of the SCR control unit. The qua