<div class="section abstract"><div class="htmlview paragraph">With the introduction of the emission legislation Euro VI for commercial vehicles
(CVs), selective catalytic reduction (SCR) with urea water solution (UWS) as the
reducing agent has become a standard to minimize the nitrogen oxides
(NO<sub>x</sub>) emissions from internal combustion engines. The urea
processing and mixing unit has been developed and optimized in order to avoid
deposit formation and ensure a high level of urea processing over the whole
operation range, especially at lower temperatures. However, there are physical
limits to the conversion of urea in conventional processing units during very
low engine operating conditions. With the EHC Fractal Heater, Purem by
Eberspächer has developed a heating measure that, in addition to its main
function of accelerating the light-off of catalytic converters, also comes with
the possibility of improving the UWS processing, especially under these low-load
conditions.</div></div>
<div class="section abstract"><div class="htmlview paragraph">Future legislations such as EPA27 [<span class="xref">1</span>] and EURO VII [<span class="xref">2</span>] are further reducing NO<sub>x</sub> 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<sub>x</sub> is reached over a Selective Catalytic Reduction (SCR) system, with NH<sub>3</sub> as a reductant. NH<sub>3</sub> is derived over the processing of Urea Water Solution (UWS) to NH<sub>3</sub>. The conversion of UWS to NH<sub>3</sub> 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 NH<sub>3</sub> 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 NH<sub>3</sub> distribution, NH<sub>3</sub> yield and deposit formation, which can afterwards be used for an optimal application of the unit within the required boundary conditions in customer projects.</div></div>
<div class="section abstract"><div class="htmlview paragraph">With the announcement of the Euro 7 proposal, it is now clear that nitrous oxide
(laughing gas, N<sub>2</sub>O) emissions must be considered and complied with
the certification of exhaust aftertreatment systems (EATS) of commercial
vehicles (CV). This paper describes the possible formation pathways for
N<sub>2</sub>O in the EATS for different drives and uses measurement results
to show the boundary condition and the magnitude of formation as well as the
possibilities for influencing or preventing its formation.</div></div>
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