Advanced Diesel Combustion and Aftertreatment

The development of low-temperature premixedcompression ignition (PCI) combustion strategies andthe performance of diesel oxidation catalysts (DOC)are presented in this work. At moderate loads,low-temperature PCI combustion is shown tosignificantly reduce engine-out oxides of nitrogen(NOX) and soot emissions compared to a conventionaldiesel combustion strategy. The PCI load-range islimited by soot emissions at high engine loads andexcessive carbon monoxide (CO), hydrocarbon (HC)emissions and low exhaust gas temperatures low engineloads. DOC formulations are investigated on a gasbench reactor using surrogate exhaust gas mixturescontaining CO, O2, H2O, C11H24, C2H4 and N2.Light-off tests show delayed catalyst light-off inthe presence of PCI exhaust. CO and HC are convertedto 100% and 98% respectively under fully litconditions. Engine experiments agree well withreactor experiments. DOC formulations containingzeolites adsorb HC at low temperatures. HC speciationshows that HCs of carbon number five and higher aretrapped on zeolite at low temperatures. CO conversionis 100% through the fully active catalyst; HCconversion is lower compared to the reactor experiments.