Impact of Choice of Spray Inputs on Simulations of Urea-Based Selective Catalytic Reduction Systems

Numerical and Experimental Investigation of Ammonia Uniformity in a Compact Selective Catalytic Reduction System

“…UWS spray was injected using a pressure swirl atomizer, which had been experimentally characterized in our previous work. 15 A summary of the key characteristics of the injector used is reported in Table 2. UWS dosing was triggered externally so that the laser could be synchronized with the injection event.…”

“…32 The meshing strategy was based on findings from our previous work. 15 A predominantly hexahedral mesh was generated with a base mesh size of 5 mm with local refinements on the swirl mixer, the perforated plate and in the spray core region. The total number of cells were ∼2.8 million with 4000 cells on the catalyst inlet face.…”

“…More details on the specifications for spray inputs can be found in our previous work. 15 The SCR-thermolysis model of AVL FIRE 32 was used to model the two-step process of water evaporation and urea thermolysis. In the first step, water evaporation is first considered using the multicomponent version of the Abramzon−Sirignano evaporation model.…”

“…The engine was operated at each desired speed and load point until the system reached stability with regard to coolant, oil, and DPF outlet temperatures. UWS spray was injected using a pressure swirl atomizer, which had been experimentally characterized in our previous work . A summary of the key characteristics of the injector used is reported in Table .…”

“…These simulations are typically based on the Eulerian–Lagrangian framework where exhaust gas is modeled as the continuum phase and spray droplets are modeled as discrete particles. There are numerous studies available in the literature focused on modeling of the relevant physical processes such as UWS spray injection, − spray decomposition, , spray-wall impingement, − heat transfer, , and film formation. , However, there are only a limited number of studies comparing CFD predictions of ammonia uniformity against physical measurements. Fischer et al investigated the impact of the turbulence model and differencing scheme on ammonia uniformity prediction.…”