[Shelbi S]

https://www.youtube.com/watch?v=LnlHJ26ucHw

This video shows a simulation of urea deposit formation on a clamshell mixer. In a urea/SCR aftertreatment system, the clamshell mixer enhances the mixing of ammonia with the incoming exhaust gasses. A more uniform distribution of ammonia at the SCR inlet will result in better NOx reduction. However, in adverse flow conditions (e.g., low temperatures and high flow rates), undecomposed urea can form solid deposits on the mixer walls, which degrades the performance of the system. The first view shows the deposit formation with the mixer colored by temperature. In the second view, the film parcels are hidden to show how the spray cools the surface of the mixer. The final view shows the film thickness over time. A 12-step detailed urea decomposition mechanism was used in conjunction with conjugate heat transfer modeling, super-cycling, and fixed flow to predict the urea deposits.