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Vehicles that meet the Federal Tier II and the California LEV II Vehicle Standards (e.g. ULEV and SULEV) are a rapidly growing percentage of the fleet. Sales weighted fleet average emissions of new vehicles are already below the LEV certification levels and should be below ULEV certification levels within two years. ULEV and SULEV vehicles represent the “typical” vehicle future for the next decade or two. Data on particulate emissions from these vehicles are currently very limited. In this study, emission tests using the standard Federal Test Procedure (FTP) were conducted on a small in-use vehicle fleet of ULEV and SULEV vehicles to determine their particulate matter mass emission rates, chemical compositions, particle numbers, and particle size distributions. Particulate sampling utilized Teflon filters for mass determination and quartz filters + PUF-XAD cartridges for chemical speciation. Each bag of the test was sampled separately.

Although studies have shown benefits in both emissions and fuel renewability for hydrogen fuelled vehicles, implementation of such a vehicle has been slow due, in part, to a limited hydrogen infrastructure. This situation, along with the proven benefits associated with natural gas and natural gas/hydrogen fuelled vehicles resulted in the need to develop a vehicle capable of operating on any blend of natural gas/hydrogen, at anytime. Such a vehicle dubbed; Variable Gaseous Fuel (VGF) vehicle, in principle, could use a thermal conductivity sensing device developed at the University of California, Riverside, College of Engineering - Center for Environmental Research and Technology (CE-CERT) to directly measure the composition of a natural gas/hydrogen blend. The resulting electrical signal from this device can, in turn, be used as an input to “multiple map” engine control module to control fuel injection and ignition timing.

FTP-UDDS (urban dynamometer driving schedule) exhaust particulate matter (PM) emission rates were determined for 361 light-duty gasoline (LDGV) and 49 diesel passenger vehicles ranging in model year (MY) from 1965 to 1997. LDGVs were recruited into four MY categories. In addition, special effort was made to recruit LDGVs with visible smoke emissions, since these vehicles may be significant contributors to the mobile source PM emission inventory. Both light and heavy-duty diesels where included in the passenger diesel test fleet, which was insufficient in size to separate into the same MY categories as the LDGVs. Vehicles were tested as-received in three areas: Denver, Colorado; San Antonio, Texas; and the South Coast Air Quality Management District, California. The average PM emission rates were 3.3, 79.9, 384 and 558 mg/mi for 1991-97 MY LDGVs, pre-1981 LDGVs, smoking LDGVs and the diesel vehicles, respectively.