Development and Optimization of Simulation and Testing Methods for the Rating of Compact Urea Processing Units for Serial Applications for Lean Combustion Engines

Future legislations such as EPA27 [1] and EURO VII [2] are further reducing NO_x emission limits. At the same time, the focus of emission compliance over a broad range of operation conditions is becoming more stringent; with a specific focus onto the cold start. The reduction of NO_x is reached over a Selective Catalytic Reduction (SCR) system, with NH₃ as a reductant. NH₃ is derived over the processing of Urea Water Solution (UWS) to NH₃. The conversion of UWS to NH₃ is a highly complex process, with the danger of deposit formation, which is especially challenging in Compact Urea Processing Units (CUPU). One of the key factors for the successful development of Compact Urea Processing Units is the precise application of simulation and testing methods. Therefore, existing testing methods e.g. for the determination of the urea processing capability or the deposit formation were optimized, new testing methods are being introduced and the parameters evaluated are being broadened. For the simulation it is mandatory to use validated models to ensure a good correlation between simulation and testing. For this reason, the simulation tools, e.g. for the determination of the NH₃ distribution, were evaluated and adjusted to deliver reliable results. The results gained in testing and simulations are not only evaluated individually, but in combination amongst each other. This leads to a full picture and an in-depth understanding of the UWS processing in a CUPU. Moreover, it leads to a fuller understanding of the impacting parameters of NH₃ distribution, NH₃ yield and deposit formation, which can afterwards be used for an optimal application of the unit within the required boundary conditions in customer projects.