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With a tighter regulatory environment, reduction of hydrocarbon (HC) and NOx emissions during cold-start has emerged as a major challenge for diesel engines. In the complex diesel aftertreatment system, more than 90% of engine-out NOx is removed in the underfloor SCR. However, the combination of low temperature exhaust and heat sink over DOC delays the SCR light-off during the cold start. In fact, the first 350 seconds during the cold light-duty FTP75 cycle contribute more than 50% of the total NOx tailpipe emission due to the low SCR temperature. For a fast SCR light-off, electrically heated catalyst (EHC) technology has been suggested to be an effective solution as a rapid warm-up strategy. In this work, the EHC, placed in front of DOC, utilizes both electrical power and hydrocarbon fuel. The smart energy management during the cold-start was crucial to optimize the EHC integrated aftertreatment system.

Increasingly stringent CO2 emission standards have been legislated; in part to encourage OEM's to develop more efficient propulsion systems. These development efforts have typically focused on improving steady state operation, but recently there has been increased interest on the improvement potential during dynamic behavior. In particular the warm-up behavior of combustion engines is a field of increasing investigation. This warm-up behavior is especially pertinent in Europe, where customers tend to drive shorter distances, and the New European Driving Cycle (NEDC) reflects this driving pattern. The desire to influence this warm-up behavior is typically referred to as thermal management. Thermal management may be considered as “heat brokering” where the optimum flow of heat is to be decided, e.g. take heat from exhaust or coolant and feed it to coolant or oil. The goal is to reduce fuel consumption by achieving the most efficient warm-up of the powertrain.