Fast Diesel Aftertreatment Heat-up Using CDA and an Electrical Heater

Commercial vehicles require fast aftertreatment heat-up in order to move the SCR catalyst into the most efficient temperature range to meet upcoming NO_X regulations. Today’s diesel aftertreatment systems require on the order of 10 minutes to heat up during a cold FTP cycle. The focus of this paper is to heat up the aftertreatment system as quickly as possible during cold starts and maintain a high temperature during low load, while minimizing fuel consumption. A system solution is demonstrated using a heavy-duty diesel engine with an end-of-life aged aftertreatment system targeted for 2027 emission levels using various levels of controls. The baseline layer of controls includes cylinder deactivation to raise the exhaust temperature more than 100° C in combination with elevated idle speed to increase the mass flowrate through the aftertreatment system. The combination yields higher exhaust enthalpy through the aftertreatment system. The added layer of controls is an electric heater (EH) upstream of the SCR catalyst. The engine load is adjusted to compensate for generating the electrical power on the engine. The combination of electrical heat, added load, cylinder deactivation and elevated idle speed allows the aftertreatment system to heat up in a small fraction of the time required by today’s systems. This work was quantified over the cold FTP, hot FTP, low load cycle (LLC) and the U.S. beverage cycle showing improved NO_X and CO₂ emissions. The improvement in NO_X reduction and the CO₂ savings over these cycles are highlighted.