Advanced Dual Dosing DeNOx System for Optimized NOx Reduction Under Future Emission Regulations

The evolution of global emission standards has imposed increasingly stringent limits on nitrogen oxide (NOx) emissions, particularly under Real Driving Emissions (RDE) testing protocols. These requirements demand effective NOx control across a wide range of operating conditions, posing a challenge for conventional single-injector Selective Catalytic Reduction (SCR) systems. This paper briefs about Dual Dosing SCR System designed to enhance NOx reduction performance by employing two Diesel Exhaust Fluid (DEF) injectors integrated within an advanced exhaust after-treatment system (EATS) configuration. The system features a close-coupled SCR on DPF (SDPF) followed by an underfloor SCR (UFSCR), enabling staged ammonia dosing. This layout promotes improved ammonia distribution and catalytic performance across both low-load and high-speed driving conditions. An Electronic Control Unit (ECU) governs the DEF injection using predefined dosing maps, with reference to real-time data from three NOx sensors placed at strategic locations: upstream of the SDPF, between the SDPF and UFSCR, and downstream of the UFSCR. The dual stage dosing strategy is calibrated to maintain optimal ammonia storage on the catalyst surfaces, while minimizing ammonia slip events through precise flow rate control and system monitoring. Attention to DEF injector thermal management and catalyst aging behavior ensures system robustness over extended operating lifetimes and diverse driving profiles. Although closed-loop control is not yet implemented, the sensor data provides valuable insight for monitoring system performance, tuning the dosing strategy, and evaluating NOx conversion effectiveness. Simulation results and preliminary prototype testing indicate that this dual dosing configuration can achieve up to 95% NOx conversion efficiency under selected conditions, offering significant improvements over conventional single-injector systems, particularly during transient operations. This approach offers a practical foundation for meeting evolving emissions regulations while preserving engine performance and fuel economy, with the potential for future enhancement through closed-loop optimization.