Chapter 15: Development of Combined NSR DeNO_x and DeSO_x Model and Application for Control Strategy Pre-calibration of a Modern Diesel Engine

NSR systems represent a cost-efficient aftertreatment system for NO_x reduction of diesel engines in small passenger cars. Sulfur poisoning is one of the major challenges of NSR catalysts, since it reduces NO_x storage and conversion efficiency. To release the sulfur from NSR, a desulfation strategy is applied to the catalyst by increasing catalyst temperature and oscillating between lean and rich engine operating condition. In the present work, a commercial NSR catalyst is studied. First a small-scale catalyst is investigated in synthetic gas bench and chemical mechanisms are proposed accordingly to explain NO_x storage and reduction as well as sulfur storage and release in NSR. The developed mechanisms are implemented in a physico-chemical model and the reactions are calibrated according to the observed behaviour. Later the model is verified by correct prediction of a full-scale NSR performance in an engine bench with real exhaust line and under transient operation of engine. Finally, the NSR model is coupled with a virtual diesel engine platform and a real driving condition is simulated to estimate engine out emission and predict NSR efficiency to reduce tail NO_x concentration. The developed modelling capability will be used to support NSR catalyst design and engine calibration optimization in model based development environment.