Challenge
An industrial engine manufacturer needed to validate its SCR aftertreatment system against tightening emission standards. Key risks were elevated exhaust backpressure — penalising engine efficiency — and poor DEF/AdBlue distribution causing uneven NOx conversion and urea crystallisation.
Scope of Work
- ● CAD geometry import, cleanup & mesh generation
- ● Exhaust gas flow simulation through mixer, diffuser, catalyst & outlet
- ● Pressure drop breakdown by component
- ● DEF spray injection, droplet evaporation & Uniformity Index analysis
- ● Wall wetting, crystallisation & deposit risk assessment
System Architecture
Backpressure Analysis
Results & Outcomes
Backpressure Reduced
Flow restrictions located and quantified per component. Mixer geometry redesigned to lower total system pressure drop.
Flow Uniformity Improved
Exhaust distribution at catalyst face made uniform, ensuring consistent washcoat utilisation across the full cross-section.
DEF Mixing Enhanced
Ammonia Uniformity Index at SCR inlet improved through injector placement refinement, reducing ammonia slip and catalyst deactivation risk.
Deposit Risk Mitigated
Wall impingement analysis identified crystallisation zones. Design modifications eliminated liquid film formation and hot-spot conditions.
Key Deliverables
- ● Backpressure assessment report
- ● Pressure drop breakdown by component
- ● Flow uniformity analysis
- ● Urea spray distribution evaluation
- ● Ammonia uniformity at SCR inlet
- ● Design improvement recommendations
Value Delivered
APA Engineering’s CFD-led approach resolved system-level flow and spray issues in simulation before physical build — avoiding costly prototype cycles, compressing the development timeline, and delivering an emissions-compliant SCR design with a validated performance baseline
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