The Effect of Different Air Path Based ATS Thermal Management Strategy on a Non- EGR Medium Duty Diesel Engine’s Performance and Emissions 2024-26-0038

The major objective of this paper is to develop thermal management strategy targeting optimum performance of Selective Catalytic Reduction (SCR) catalyst in a Medium Duty Diesel Engine performing in BS6 emission cycles.

In the current scenario, the Emissions Norms are becoming more stringent and with the introduction of Real Drive Emission Test (RDE) and WHTC test comprising of both cold and hot phase, there is a need to develop techniques and strategies which are quick to respond in real time to cope with emission limit especially NOx. SCR seems to be suitable solution in reducing NOx in real time. However, there are limitations to SCR operating conditions, the major being the dosing release conditions which defines the gas temperature at which DEF (Diesel Exhaust Fluid) can be injected as DEF injection at lower gas temperatures than dosing release will lead to Urea deposit formation and will significantly hamper the SCR performance. The second factor for optimum SCR operation is to maintain the catalyst temperature where high NOx conversion efficiency is obtained.

Dosing release temperature plays an important role to achieve high NOx conversion efficiency, specifically when the aftertreatment system is at ambient temperature. Therefore, thermal management strategy is employed to ensure quick heating of ATS to achieve the Dosing release temperature in the shortest possible time duration. Thermal management involves air path control where actuators are used to alter the exhaust temperature, and also the injection strategies that favors higher exhaust enthalpy at the cost of BSFC. Thermal Management is active until the ATS will reach the certain temperature threshold beyond which the thermal management will be deactivated as prolong activation of thermal management may result in fuel penalty. From the airpath point of view the focus of this paper is towards the utilization of intake throttling, engine brake and variable exhaust flap. Along with the airpath, the impact of combustion retardation is also covered.