Modeling of Aqueous Urea Solution Injection with Characterization of Spray-wall Cooling Effect and Risk of Onset of Wall Wetting

AbstractThe definition of a sufficiently resolved heat transfer model with spray cooling effect as a function of each droplet kinetic and thermal parameters is a key factor in the numerical simulation of aqueous urea (AUS) based Selective Catalytic Reduction (SCR) exhaust after-treatment systems.A consolidated spray-wall interaction model [1] has been implemented on the open source 3D finite volume software OpenFOAM and a critical investigation of its behaviour in engine representative conditions is reported.A simplified test case is used to highlight the influence of the chosen model on the numerical simulation of the system, reducing the importance of the other spray sub-models in the Lagrangian-Eulerian computational framework. The coupling between the droplet evaporation heat flux and the gas-solid interface thermal boundary condition has been studied, pointing out the significance of each contribution.The main focus of this work is to present reference conditions to simulate the spray-dry wall spray impingement behavior to determine the ‘onset of wall wetting’ thermal conditions