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The benefits associated with the use of oxygen-containing diesel fuels in passenger cars are quite well described in the literature. This work describes the results of an 18-meter EEV city bus fueled with diesel fuel with the addition of 10% v/v of triethylene glycol dimethyl ether. This compound was chosen because it was effective in reducing exhaust emissions from light duty diesel vehicles. Emission tests (CO, HC, NOx and PM) of the city bus were performed over SORT (Standardized On-Road Tests) cycles using portable exhaust gas analyzers - PEMS. Significant differences in the emission of exhaust components were observed in individual SORT cycles. The level of road emissions reduced as the traffic smoothness increased, i.e. from the SORT 1 to SORT 3 cycle. The largest reduction in bus emissions associated with the use of the oxygenated additive (triethylene glycol dimethyl ether) applies to carbon monoxide and ranges from 50% for the SORT 3 cycle up to 90% for the SORT 1.

The paper presents an analysis of the emission level from a heavy-duty truck of the GVW of 12,000 kg. The exhaust emission tests were performed under actual traffic conditions in the area of Poznań. For the tests portable exhaust emission analyzers SEMTECH DS and AVL Micro Soot Sensor were used. The characteristics of the exhaust emission components have been determined in relation to the engine speed and load as well as vehicle parameters (speed and acceleration). The paper includes an analysis of the engine operating conditions as well as the range of engine speeds and engine loads. The vehicle fuel consumption was also determined through the carbon balance method. Based on the obtained values of the emission of CO, NOx and PM, the emission indexes were determined that provided information on the relation of the measured emissions to the levels specified in the EEV standard. The emissions of all the exhaust components, except NOx were lower than the EEV limits.

Research on the influence of oxygenated diesel fuels on the PM/NOx emission trade-off was carried out with use of 11 different synthetic oxygenated compounds, representing 3 chemical groups (glycol ethers, maleates, carbonates). Each of oxygenates were evaluated as a fuel additive at a concentration of 5% v/v in the same base diesel fuel. The tests were conducted on a passenger car equipped with a common rail turbocharged diesel engine over the European cycle NEDC and US FTP-75 cycle. All the tested oxygenates caused a reduction in PM emissions and most of them caused a certain increase in NOx emissions. The changes in emissions depended on the oxygenate type and cycle. In general, the favorable and unfavorable influence of oxygenated compounds was more intensive during the NEDC, which is a softer and less transient cycle than the FTP-75. The most favorable changes in the PM/NOx emission trade-off were obtained for maleates and carbonates.

The paper presents the test results relating to the influence of carbonate oxygenated additives to diesel fuel on exhaust emissions. Following the previous tests of glycol ethers (SAE Paper 2007-01-0069) and maleates (SAE Paper 2008-01-1813), the authors decided to use carbonates to obtain an even greater reduction in PM emissions. The significant effectiveness of carbonates on PM emission reduction was confirmed in tests performed by the authors. Diethyl carbonate was the most effective oxygenated compound with regard to PM emission reduction among all the 11 oxygenates which have been tested so far. Moreover, it is important to note that diethyl carbonate caused only a small increase in NOx emissions, thus it allowed for an essential improvement in the PM/NOx trade-off. A significant increase in the CO and HC emissions was, however, a negative effect of the use of carbonates.

The paper presents the test results of the influence of maleate oxygenated additives to diesel fuel on exhaust emissions. Following the previous tests of glycol ethers (SAE Paper 2007-01-0069), the authors decided to use maleates as oxygenates to obtain greater changes in PM/NOx trade-off than the changes obtained as a result of the use of glycol ethers. It was found that in the NEDC maleates at the same concentration as in the case of glycol ethers ensure more favourable changes of PM/NOx trade-off and, as a matter of fact, caused greater reduction in PM emissions without the growth of NOx emissions, however, at the cost of CO and HC emissions. The tests performed in the FTP-75 confirmed a significantly weaker influence of maleates, both positive (PM) and negative (CO, HC) than in the NEDC. They did not find in both cycles any influence of maleates at the tested concentration upon fuel consumption and CO2 emissions.

In the year 2005, the EURO IV fuel specification came into effect and the requirements for diesel fuel properties have become even more stringent. In this way, the potential of diesel fuel for emissions reduction has already been to a large extent exploited and the most emissions-sensitive fuel parameters can now be changed in a narrow range only. The shortfall in NOx and PM emissions control in diesel engines is, however, so great that more drastic fuel changes will be needed. One of the most promising fuel modifications for exhaust emissions control seems to be oxygenated additives. The objective of the study described in this paper was to analyze under transient conditions the influence of synthetic oxygenated fuel additives on exhaust emissions. The tests were conducted on a Euro IV passenger car. Six oxygenated additives were tested over the New European Driving Cycle (NEDC).

The motor vehicle is one of the main sources of pollutant emissions, especially in urban areas. Environmentally friendly fuels are regarded as very effective means to decrease emissions. With regard to diesel engines, the reduction in nitrogen oxides and particulates are major problem areas. Although the fuel influence on NOx is comparatively low, the composition and parameters of diesel fuel have a big influence on particulate emissions and composition. Sulphur content is one of fuel proprieties, which has the most considerable influence on particulates. This paper describes results of the research on particulate emissions from diesel engines fuelled with research fuels of differing sulphur content. The sulphur content of the research fuels varied from 2000 ppm through 350 ppm (EURO III) and 50 ppm (EURO IV limit, which will be in force in the European Community from 1 January 2005) up to less than 5 ppm.