title: Will Aerosol Hygroscopicity Change with Biodiesel, Renewable Diesel Fuels and Emission Control Technologies?
abstract: The use of biodiesel and renewable diesel fuels in compression ignition engines and aftertreatment technologies may affect vehicle exhaust emissions. In this study two 2012 light-duty vehicles equipped with direct injection diesel engines, diesel oxidation catalyst (DOC), diesel particulate filter (DPF), and selective catalytic reduction (SCR) were tested on a chassis dynamometer. One vehicle was tested over the Federal Test Procedure (FTP) cycle on seven biodiesel and renewable diesel fuel blends. Both vehicles were exercised over double Environmental Protection Agency (EPA) Highway fuel economy test (HWFET) cycles on ultralow sulfur diesel (ULSD) and a soy-based biodiesel blend to investigate the aerosol hygroscopicity during the regeneration of the DPF. Overall, the apparent hygroscopicity of emissions during nonregeneration events is consistently low (κ < 0.1) for all fuels over the FTP cycle. Aerosol emitted during filter regeneration is significantly more CCN active and hygroscopic; average κ values range from 0.242 to 0.439 and are as high as 0.843. Regardless of fuel, the current classification of "fresh" tailpipe emissions as nonhygroscopic remains true during nonregeneration operation. However, aftertreatment technologies such as DPF, will produce significantly more hygroscopic particles during regeneration. To our knowledge, this is the first study to show a significant enhancement of hygroscopic materials emitted during DPF regeneration of on-road diesel vehicles. As such, the contribution of regeneration emissions from a growing fleet of diesel vehicles will be important.
authors.affiliation: Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California , Riverside, California 92521, United States.|Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT) , Riverside, California 92507, United States.
authors.forename: Diep
authors.initials: D
authors.lastname: Vu
authors.affiliation: Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California , Riverside, California 92521, United States.|Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT) , Riverside, California 92507, United States.
authors.forename: Daniel
authors.initials: D
authors.lastname: Short
authors.affiliation: Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California , Riverside, California 92521, United States.|Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT) , Riverside, California 92507, United States.
authors.forename: Georgios
authors.initials: G
authors.lastname: Karavalakis
authors.affiliation: Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California , Riverside, California 92521, United States.|Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT) , Riverside, California 92507, United States.
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Durbin
authors.affiliation: Department of Chemical and Environmental Engineering, Bourns College of Engineering, University of California , Riverside, California 92521, United States.|Bourns College of Engineering, Center for Environmental Research and Technology (CE-CERT) , Riverside, California 92507, United States.
authors.forename: Akua
authors.identifier: 0000-0002-0354-8368
authors.initials: A
authors.lastname: Asa-Awuku
mesh_terms: D000336:Aerosols; D000393:Air Pollutants; D056804:Biofuels; D005742:Gasoline; D001335:Vehicle Emissions; D017155:Wettability
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D056804:Biofuels; D005742:Gasoline; D001335:Vehicle Emissions