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Many researchers have reported the measurement of high numbers of emitted particles from gasoline vehicles operating at high speed. To date, in the absence of standard test protocols or analytical techniques, these measurements have all been made from a dilution tunnel set up according to regulatory procedures. Currently, there is great uncertainty relating to the use of the dilution tunnel as a suitable tool for the measurement of automotive particle size and number distribution and also the relevance of the procedure to ambient measurement of the same parameters. Gasoline particle number emissions, as measured on a dilution tunnel, are low at speeds under 120km/h. Beyond this speed, high numbers of very small particles have been measured. There is some evidence to show that these particles may be formed as an artefact within the sampling system, either from the desorption of deposited material or from the pyrolysis of other material in the sampling system itself.

The effect of fuel sulphur on emissions from a lean-burn G-DI passenger car homologated according to German D3 specifications was investigated over the European drive cycles. In addition some tests over US Federal cycles were conducted. No statistically significant deterioration in tailpipe emissions was detected with the leanburn G-DI technology using a selective reduction type de-NOx catalyst at fuel sulphur levels from 30 to 300 mg/kg. The emission response to fuel sulphur level was essentially flat, and the sulphur effect was less than that seen in the EPEFE fleet. Tests were conducted applying a rigorous test protocol including four repeats with each fuel and a desulphation procedure between fuel changes. Approximately 15-20% improvement in fuel economy over comparable MPI cars was predicted based on the CO2 results from the current programme and German type approval data. Increased particulate mass emissions were observed, compared with typical MPI cars.

An emissions programme has been undertaken to gain information on the effect of selected fuel parameters on gasoline direct injection (G-DI) vehicle technology(1) with respect to exhaust emissions. Seven fuel parameters, namely aromatic, methyl-tertiary-butyl ether (MTBE), sulphur and olefin content as well as 3 distillation parameters covering the whole boiling range, were independently investigated. It was found that, overall, the fuel effects on regulated (THC, CO, NOx), particulate (Pm), and CO2 emissions were relatively small.

From 1995 to 1997, the Coordinating Research Council (CRC) conducted a cold-start driveability program to evaluate the behavior of lower volatility fuels at cold, intermediate, and warm ambient temperatures. The program used 135 vehicles to evaluate 87 hydrocarbon, MTBE blended, and ethanol blended fuels. Evaporative driveability index equations (EDIs) were developed using the test design fuel variables (E158°F, E200°F, E300°F), and three other variable sets: (E158°F, E250°F, E330°F), (T10, T50, T90), and (E70°C, E100°C, E140°C). The models that best fit the data contained oxygenate offsets. Overall, the best indices are the E70°C, E100°C, E140°C equation and the DI equation with offsets.

“Gas-to-liquids” catalytic conversion technologies show promise for liberating stranded natural gas reserves and for achieving energy diversity worldwide. Some gas-to-liquids products are used as transportation fuels and as blendstocks for upgrading crude-derived fuels. Methylal (CH3-O-CH2-O-CH3), also known as dimethoxymethane or DMM, is a gas-to-liquid chemical that has been evaluated for use as a diesel fuel component. Methylal contains 42% oxygen by weight and is soluble in diesel fuel. The physical and chemical properties of neat methylal and for blends of methylal in conventional diesel fuel are presented. Methylal was found to be more volatile than diesel fuel, and special precautions for distribution and fuel tank storage are discussed. Steady state engine tests were also performed using an unmodified Cummins B5.9 turbocharged diesel engine to examine the effect of methylal blend concentration on performance and emissions.

Previous studies have shown that regenerating particulate filters are very effective at reducing particulate matter emissions from diesel engines. Some particulate filters are passive devices that can be installed in place of the muffler on both new and older model diesel engines. These passive devices could potentially be used to retrofit large numbers of trucks and buses already in service, to substantially reduce particulate matter emissions. Catalyst-type particulate filters must be used with diesel fuels having low sulfur content to avoid poisoning the catalyst. A project has been launched to evaluate a truck fleet retrofitted with two types of passive particulate filter systems and operating on diesel fuel having ultra-low sulfur content. The objective of this project is to evaluate new particulate filter and fuel technology in service, using a fleet of twenty Class 8 grocery store trucks. This paper summarizes the truck fleet start-up experience.