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In this study, the criteria pollutant emissions from a light duty vehicle equipped with Dedicated EGR® technology were compared with emissions from an identical production GDI vehicle without externally cooled EGR. In addition to the comparison of criteria pollutant mass emissions, an analysis of the gaseous and particulate chemistry was conducted to understand how the change in combustion system affects the optimal aftertreatment control system. Hydrocarbon emissions from the vehicle were analyzed usin g a variety of methods to quantify over 200 compounds ranging in HC chain length from C1 to C12. The particulate emissions were also characterized to quantify particulate mass and number. Gaseous and particulate emissions were sampled and analyzed from both vehicles operating on the FTP-75, HWFET, US06, and WLTP drive cycles at the engine outlet location.

The size and distribution of a vehicle’s tailpipe particulate emissions can have a strong impact on human health, especially if the particles are small enough to enter the human respiratory system. Gasoline direct injection (GDI) has been adopted widely to meet stringent fuel economy and CO2 regulations across the globe for recent engine architectures. However, the introduction of GDI has led to challenges concerning the particulate matter (PM) and particle number (PN) emissions from such engines. This study aimed to compare the particulate emissions of three SI combustion strategies: conventional SI, conventional stoichiometric low-pressure exhaust gas recirculation (LP-EGR), and Dedicated-EGR (D-EGR) at four specific test conditions. It was shown that the engine-out PM/PN for both the EGR strategies was lower than the conventional SI combustion under normal operating conditions. The test conditions were chosen to represent the WLTC test conditions.

Detailed characterization of particle emissions from three different engine technologies were performed, two of which were advanced technology engines. One of the engines was a nonroad Tier 4 Final emission regulation compliant 6.8L John Deere PSS 6068 diesel engine operated with its production calibration strategy. The other two engine platforms were advanced engine technologies whose controllers were developed by Southwest Research Institute (SwRI). These included a dual fuel Navistar MaxxForce 13L natural gas-diesel engine and a Cummins ISX 15L diesel engine. The dual fuel engine was operated in two distinct modes, conventional dual fuel (CDF) mode and low temperature reactivity controlled compression ignition (RCCI) mode. The Cummins ISX engine was operated using a “hot” or low EGR combustion strategy. For each engine technology, the test campaign involved steady-state test modes ranging from low speed low load to high speed high load conditions.

As an alternative fuel, renewable diesel (RD) could improve the performance of conventional internal combustion engines (ICE) because of its difference in fuel properties. With almost no aromatic content in the fuel, RD produces less soot emissions than diesel. The higher cetane number (CN) of RD also promotes ignition of the fuel, which is critical, especially under low load, and low reactivity conditions. This study tested RD fuel in a heavy-duty single-cylinder engine (SCE) under compression-ignition (CI) operation. Test condition includes low and high load points with change in exhaust gas recirculation (EGR) and start of injection (SOI). Measurements and analysis are provided to study combustion and emissions, including particulate matters (PM) mass and particle number (PN). It was found that while the combustion of RD and diesel are very similar, PM and PN emissions of RD were reduced substantially compared to diesel.