Effects of driving conditions on secondary aerosol formation from a GDI vehicle using an oxidation flow reactor

A comprehensive study on the effects of photochemical aging on exhaust emissions from a vehicle equipped with a gasoline direct injection engine when operated over seven different driving cycles was assessed using an oxidation flow reactor. Both primary emissions and secondary aerosol production were measured over the Federal Test Procedure (FTP), LA92, New European Driving Cycle (NEDC), US06, and the Highway Fuel Economy Test (HWFET), as well as over two real-world cycles developed by the California Department of Transportation (Caltrans) mimicking typical highway driving conditions. We showed that the emissions of primary particles were largely depended on cold-start conditions and acceleration events. Secondary organic aerosol (SOA) formation also exhibited strong dependence on the cold-start cycles and correlated well with SOA precursor emissions (i.e., non-methane hydrocarbons, NMHC) during both cold-start and hot-start cycles (correlation coefficients 0.95–0.99), with overall emissions of ∼68–94 mg SOA per g NMHC. SOA formation significantly dropped during the hot-running phases of the cycles, with simultaneous increases in nitrate and ammonium formation as a result of the higher nitrogen oxide (NOx) and ammonia emissions. Our findings suggest that more SOA will be produced during congested, slow speed, and braking events in highways.acceptedVersionPeer reviewe

Impact of Emission Control Systems and Alternative Fuels on Off-Road and On-Road Internal Combustion Engines

Internal combustion engines (ICEs) represent one of the largest sources of emissions leading to air pollution in the united states. Emissions from ICEs pose a large issue due to human health and environmental effects, but they can be controlled. This dissertation is an investigation into the pollutants emitted from ICEs for a range of applications and the usefulness of available emission control strategies different fuel sources. The range of ICEs includes small off-road diesel engines, light duty gasoline and diesel engines, heavy duty diesel and alternative fuel engines, and large marine engines. The control technologies included gasoline particulate filters (GPFs), selective catalytic reduction (SCR), and diesel particulate filters (DPFs), and the alternative fuels included hydrogenated vegetable oil (HVO), biodiesel HVO fuel blends, natural gas (NG), liquefied petroleum gas (LPG), diesel-electric hybrids, marine gas oil (MGO) and ultra-low sulfur heavy fuel oil (ULSHFO). As renewable fuel sources gain more attention for their ability to reduce the overall greenhouse gas impacts of ICEs, it is important to fully understand the emissions of new renewable fuel sources. This dissertation provides an investigation into the fuel impacts and engine impacts of a second-generation biofuel, HVO, and fuel blends of HVO and biodiesel in light duty and heavy-duty diesel engines. This dissertation also investigates the toxicity of pollutants from heavy duty diesel engines utilizing HVO and HVO biodiesel fuel blends. Laboratory testing follows standardized and repeatable procedures that allow emissions of different models of vehicles to be compared to each other. In real-world driving however, there are many variables that can affect emissions which cannot be reproduced in a laboratory, so it is important to investigate and understand the emissions during real world driving. This dissertation provides an investigation into emissions formations of light duty gasoline direct injection (GDI) engines and heavy-duty vehicles during real world driving Off-road engines represent one of the largest sources of PM and NOx in California and nationwide. This dissertation investigated large ocean-going vessels (OGVs) utilizing two fuels and the feasibility of applying new stringent standards to small off-road diesel engines (SORDEs). The results of the SORDE study suggest that it is now feasible to apply more stringent emissions controls for the SORDE category of mobile sources

Impact of Emission Control Systems and Alternative Fuels on Off-Road and On-Road Internal Combustion Engines

Internal combustion engines (ICEs) represent one of the largest sources of emissions leading to air pollution in the united states. Emissions from ICEs pose a large issue due to human health and environmental effects, but they can be controlled. This dissertation is an investigation into the pollutants emitted from ICEs for a range of applications and the usefulness of available emission control strategies different fuel sources. The range of ICEs includes small off-road diesel engines, light duty gasoline and diesel engines, heavy duty diesel and alternative fuel engines, and large marine engines. The control technologies included gasoline particulate filters (GPFs), selective catalytic reduction (SCR), and diesel particulate filters (DPFs), and the alternative fuels included hydrogenated vegetable oil (HVO), biodiesel HVO fuel blends, natural gas (NG), liquefied petroleum gas (LPG), diesel-electric hybrids, marine gas oil (MGO) and ultra-low sulfur heavy fuel oil (ULSHFO). As renewable fuel sources gain more attention for their ability to reduce the overall greenhouse gas impacts of ICEs, it is important to fully understand the emissions of new renewable fuel sources. This dissertation provides an investigation into the fuel impacts and engine impacts of a second-generation biofuel, HVO, and fuel blends of HVO and biodiesel in light duty and heavy-duty diesel engines. This dissertation also investigates the toxicity of pollutants from heavy duty diesel engines utilizing HVO and HVO biodiesel fuel blends. Laboratory testing follows standardized and repeatable procedures that allow emissions of different models of vehicles to be compared to each other. In real-world driving however, there are many variables that can affect emissions which cannot be reproduced in a laboratory, so it is important to investigate and understand the emissions during real world driving. This dissertation provides an investigation into emissions formations of light duty gasoline direct injection (GDI) engines and heavy-duty vehicles during real world driving Off-road engines represent one of the largest sources of PM and NOx in California and nationwide. This dissertation investigated large ocean-going vessels (OGVs) utilizing two fuels and the feasibility of applying new stringent standards to small off-road diesel engines (SORDEs). The results of the SORDE study suggest that it is now feasible to apply more stringent emissions controls for the SORDE category of mobile sources

Secondary Organic and Inorganic Aerosol Formation from a GDI Vehicle under Different Driving Conditions

This study investigated the primary emissions and secondary aerosol formation from a gasoline direct injection (GDI) passenger car when operated over different legislative and real-world driving cycles on a chassis dynamometer. Diluted vehicle exhaust was photooxidized in a 30 m3 environmental chamber. Results showed elevated gaseous and particulate emissions for the cold-start cycles and higher secondary organic aerosol (SOA) formation, suggesting that cold-start condition will generate higher concentrations of SOA precursors. Total secondary aerosol mass exceeded primary PM emissions and was dominated by inorganic aerosol (ammonium and nitrate) for all driving cycles. Further chamber experiments in high temperature conditions verified that more ammonium nitrate nucleates to form new particles, forming a secondary peak in particle size distribution instead of condensing to black carbon particles. The results of this study revealed that the absorption of radiation by black carbon particles can lead to changes in secondary ammonium nitrate formation. Our work indicates the potential formation of new ammonium nitrate particles during low temperature conditions favored by the tailpipe ammonia and nitrogen oxide emissions from gasoline vehicles.publishedVersionPeer reviewe

Using an oxidation flow reactor to understand the effects of gasoline aromatics and ethanol levels on secondary aerosol formation

Fuel type and composition affect tailpipe emissions and secondary aerosol production from mobile sources. This study assessed the influence of gasoline fuels with varying levels of aromatics and ethanol on the primary emissions and secondary aerosol formation from a flexible fuel vehicle equipped with a port fuel injection engine. The vehicle was exercised over the LA92 and US06 driving cycles using a chassis dynamometer. Secondary aerosol formation potential was measured using a fast oxidation flow reactor. Results showed that the high aromatics fuels led to higher gaseous regulated emissions, as well as particulate matter (PM), black carbon, and total and solid particle number. The high ethanol content fuel (E78) resulted in reductions for the gaseous regulated pollutants and particulate emissions, with some exceptions where elevated emissions were seen for this fuel compared to both E10 fuels, depending on the driving cycle. Secondary aerosol formation potential was dominated by the cold-start phase and increased for the high aromatics fuel. Secondary aerosol formation was seen in lower levels for E78 due to the lower formation of precursor emissions using this fuel. In addition, operating driving conditions and aftertreatment efficiency played a major role on secondary organic and inorganic aerosol formation, indicating that fuel properties, driving conditions, and exhaust aftertreatment should be considered when evaluating the emissions of secondary aerosol precursors from mobile sources.Peer reviewe

Using an oxidation flow reactor to understand the effects of gasoline aromatics and ethanol levels on secondary aerosol formation

Fuel type and composition affect tailpipe emissions and secondary aerosol production from mobile sources. This study assessed the influence of gasoline fuels with varying levels of aromatics and ethanol on the primary emissions and secondary aerosol formation from a flexible fuel vehicle equipped with a port fuel injection engine. The vehicle was exercised over the LA92 and US06 driving cycles using a chassis dynamometer. Secondary aerosol formation potential was measured using a fast oxidation flow reactor. Results showed that the high aromatics fuels led to higher gaseous regulated emissions, as well as particulate matter (PM), black carbon, and total and solid particle number. The high ethanol content fuel (E78) resulted in reductions for the gaseous regulated pollutants and particulate emissions, with some exceptions where elevated emissions were seen for this fuel compared to both E10 fuels, depending on the driving cycle. Secondary aerosol formation potential was dominated by the cold-start phase and increased for the high aromatics fuel. Secondary aerosol formation was seen in lower levels for E78 due to the lower formation of precursor emissions using this fuel. In addition, operating driving conditions and aftertreatment efficiency played a major role on secondary organic and inorganic aerosol formation, indicating that fuel properties, driving conditions, and exhaust aftertreatment should be considered when evaluating the emissions of secondary aerosol precursors from mobile sources.</p

Effects of driving conditions on secondary aerosol formation from a GDI vehicle using an oxidation flow reactor

A comprehensive study on the effects of photochemical aging on exhaust emissions from a vehicle equipped with a gasoline direct injection engine when operated over seven different driving cycles was assessed using an oxidation flow reactor. Both primary emissions and secondary aerosol production were measured over the Federal Test Procedure (FTP), LA92, New European Driving Cycle (NEDC), US06, and the Highway Fuel Economy Test (HWFET), as well as over two real-world cycles developed by the California Department of Transportation (Caltrans) mimicking typical highway driving conditions. We showed that the emissions of primary particles were largely depended on cold-start conditions and acceleration events. Secondary organic aerosol (SOA) formation also exhibited strong dependence on the cold-start cycles and correlated well with SOA precursor emissions (i.e., non-methane hydrocarbons, NMHC) during both cold-start and hot-start cycles (correlation coefficients 0.95–0.99), with overall emissions of ∼68–94 mg SOA per g NMHC. SOA formation significantly dropped during the hot-running phases of the cycles, with simultaneous increases in nitrate and ammonium formation as a result of the higher nitrogen oxide (NOx) and ammonia emissions. Our findings suggest that more SOA will be produced during congested, slow speed, and braking events in highways.</p