Uncertainties in Model-Based Diesel Particulate Filter Diagnostics Using a Soot Sensor.

Monitoring the filtration efficiency of the diesel particulate filter (DPF), is a legislative requirement for minimizing particulate matter (PM) emissions from diesel engines of passenger cars and heavy-duty vehicles. To reach this target, on-board diagnostics (OBD) in real-time operation are required. Such systems in passenger cars are often utilizing a soot sensor, models for PM emissions simulation and algorithms for diagnosis. Their performance is associated with a series of challenges related to the accuracy and effectiveness of involved models, algorithms and hardware. This paper analyzes the main influencing factors and their impact on the effectiveness of the OBD system. The followed method comprised an error propagation analysis to quantify the error of detection during a New European Driving Cycle (NEDC). The results of the study regarding the performance of the OBD model showed that the total error of diagnosis is ±28%. This performance can be improved by increasing the sensor accuracy and the soot model, which can make the model appropriate for even tighter legislation limits and other approaches such as on-board monitoring (OBM).

Accuracy of exhaust emission factor measurements on chassis dynamometer.

To improve the accuracy, reliability, and representativeness of emission factors, 10 European laboratories worked together to study the influence of 20 parameters on the measurement of light-vehicle emission factors on chassis dynamometer of 4 main categories: driving patterns, vehicle-related parameters, vehicle sampling, and laboratory-related parameters. The results are based on (1) literature synthesis, (2) approximately 2700 specific tests with 183 vehicles, and (3) the reprocessing of more than 900 tests. These tests concern the regulated atmospheric pollutants and pre-Euro to Euro 4 vehicles. Of the 20 parameters analyzed, 7 seemed to have no effect, 7 were qualitatively influential, and 6 were highly influential (gearshift strategy, vehicle mileage, ambient temperature, humidity, dilution ratio, and driving cycle). The first four of the six were able to have correction factors developed for them. The results allow for the design of recommendations or guidelines for the emission factor measurement method.

Effect on exhaust emissions by the use of methylcyclopentadienyl manganese tricarbonyl (MMT) fuel additive and other lead replacement gasolines.

This paper examines the potential effects on car exhaust emissions of a range of alternative lead replacement gasolines in the context of south European countries such as Greece. The main objective of this study was to assess the effects on emissions from non-catalyst passenger vehicles by the substitution of leaded ('super') gasoline with Euro95 unleaded enriched with the additive MMT or other alternative to leaded gasoline fuels. Regulated emissions, two non-regulated pollutants and vehicle performance were measured on two catalyst-equipped and two conventional, non-catalyst vehicles. It was found that there was no measurable effect on regulated emissions (CO, HC and NO(x)) and on fuel consumption by the introduction of the lead replacement fuels for both catalyst and non-catalyst cars. In the case of the non-catalyst car, the shift from leaded to unleaded gasoline was associated with an increase in benzene and formaldehyde emissions, a trend probably attributable to the increased aromatics content of the lead replacement fuels.