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S. Fischer, T. Lauer:
"Urea‐injection and ‐preparation in Diesel applications, Multiphase multicomponent modeling using Star‐CD";
Talk: STAR European Conference 2010, London (invited); 2010-03-23 - 2010-03-24; in: "STAR European Conference 2010", STAR European (ed.); (2010), 15 pages.

The most promising approach to fulfill the Diesel engine´s future NOx‐emission limits is exhaust gas aftertreatment with the Selective Catalytic Reduction (SCR). The state‐of‐the‐art approach in automotive technology is the supply of a chemical reductant (ammonia) which is prepared from a Urea‐Water‐solution spray inserted into the exhaust gas upstream of an SCR‐catalyst.
At the Institute For Powertrains And Automotive Technology Star‐ CD was used to understand the complex process of ammonia preparation. The code has to deal with multiphase fluid dynamics in combination with multicomponent thermodynamics. We present the analysis of available submodels for the impingement of the multicomponent urea‐water‐spray on the hot walls of the exhaust pipes, focusing on liquid film formation and -dynamics. This includes the presentation of a solving strategy in Star‐CD to overcome the gap in timesteps of fast droplet dynamics and relatively slow liquid film dynamics. Moreover Star‐CD`s multicomponent droplet‐ and film‐evaporation capabilities to simulate the formation of vaporised ammonia from the urea‐water‐solution have been examined. The submodel for the complex phenomenon of liquid‐film‐boiling has been studied and evaluated in detail. In this context the role of modelling the thermal wall boundary condition via Conjugate Heat Transfer will be pointed out. The necessity of complex physical theories