Analysis of spray dynamics of urea–water-solution jets in a SCR-DeNOx system: An LES based study

Highlights: • An LES-based investigation of UWS injection into SCR like system for the first time. • A first time consideration of complete atomization process in such in-vestigations. • Integration of an advanced droplet collision–coalescence model. • Detailed validation of UWS spray dynamics with recently available experimental data. • Analysis of the interaction evaporating spray/hot gas cross flow. - Abstract: Among various advanced emission control technologies used to reduce NOx emission from diesel engines, the selective catalytic reduction (SCR) technique has proven to be more efficient. However, it is still facing the improvement of low temperature performance and the avoidance of urea deposit formation due to complex spray–wall interaction process. To gain more deep understanding of these processes, a spray module is developed for the first time within a full LES framework based on an Eulerian–Lagrangian approach. It includes especially (1) a primary and a secondary breakup model along with an advanced collision model, both to account for the atomization generated close to the nozzle exit by the multi-hole circular orifice injector used and (2) a multi-component droplet evaporation model along with a two-way coupling between the carrier gaseous phase and the droplet liquid phase throughout the dilute spray region. The suggested model is applied to evaluate the dynamics of the multi-component droplets spray resulting from an adBlue injection into a hot gas cross flow inside a channel mimicking a SCR-DeNOx flow system. First, an assessment of the multi-component droplet evaporation under hot stagnant gas environment is made. Second, the results of the adBlue spray/gas phase cross flow interaction are reported in terms of comparison between experimental data (spray structure, spray angle and penetration depth, droplet size distribution and velocity) with numerical simulations. It turns out that the model designed is able to capture in a satisfactory way the spray properties in a SCR like system.