Selective Catalyst Reduction (SCR) systems rely on injecting a Urea–Water Solution (UWS) to neutralize NOx emissions. The critical challenge is ensuring the resulting ammonia NH3 is mixed perfectly—a process controlled by the static mixer.
The study, “Multiphase Modelling of SCR Systems: Using the Taguchi Method for Mixer Optimisation,” used CFD simulation and the Taguchi Method to find the ideal mixer design, balancing NH3 uniformity, low pressure drop, and prevention of wall film.
What makes a great mixer?
The researchers tested three key geometric factors: blade angle, number of blades, and distance from the injector.
| Factor | Key finding |
| Blade angle | Major impact on NH3 distribution (Uniformity Index). This is the most effective design lever. |
| Number of blades | Impact is dependent on the blade angle, suggesting a fine-tuning role. |
| Distance from injector | Minimal effect on uniformity, but moving the mixer closer to the injector helps reduce pressure drop (improving engine efficiency). |
This article was written based on the research articles presented by active and former Katcon Global members.
Multiphase modelling of SCR systems: using the Taguchi method for mixer optimisation AJ Capetillo, F Ibarra, D Stepniewski, J Vankan – SAE International Journal of Engines, 2017