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Tighter emission norms and fuel economy demands have prompted diesel engine manufacturers to implement Aftertreatment systems for both light-duty and heavy-duty diesel applications. After implementing Diesel Particulate Filter (DPF) technology to comply with 2007 Environmental Protection Agency (EPA) emissions regulations, OEMs have turned their attention towards NOx reductions with SCR technology. Current SCR technologies include liquid based Urea injection into the exhaust stream for NOx reductions and Solid Ammonia Storage and Delivery System (ASDS) which involves dosing gaseous Ammonia. Irrespective of the technology in use, the estimation of engine-out NOx emissions plays a vital role in reductant (Urea/Ammonia) dosing estimation via feed-back controls. The general method for determination of the engine-out NOx emissions is to use commonly available NOx emission sensors (NOx Sensors). However, NOx sensors have their own drawbacks.

An integrated system model containing sub-models for a multi-cylinder diesel engine, NOx and soot(PM) emissions, diesel oxidation catalyst (DOC) and diesel particulate filter (DPF) has been developed to simulate the engine and aftertreatment systems at transient engine operating conditions. The objective of this work is two-fold; ensure correct implementation of the integrated system level model and apply the integrated model to understand the fuel economy trade-off for various DPF regeneration strategies. The current study focuses on a 1.9L turbocharged diesel engine and its exhaust system. The engine model was built in GT-Power and validated against experimental data at full-load conditions. The DPF model is calibrated for the current engine application by matching the clean DPF pressure drop for different mass flow rates. Load, boost pressure, speed and EGR controllers are tuned and linked with the current engine model.