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In view of tight emission standards, injection strategies to reduce raw HC-emissions during the cold starting of port fuel injected engines are evaluated in this study. The relevance of spray targeting and atomization is outlined in the first part of this paper. The foundation and performance of different injector concepts with respect to spray characteristics are discussed. Laboratory experiments demonstrate that concepts relying on auxiliary energy, such as air-assistance, fuel heating and injection at elevated system pressures, are capable of producing spray droplet sizes in the SMD-range of 25μm. For future injection strategies aimed at the compliance of SULEV emission levels, this target value is considered to be essential. In the second part of this paper, emission tests of selected injector concepts are carried out using a V6-3.2I ULEV engine operated both in a vehicle and on a test bench.

The results of a comprehensive experimental investigation into the exhaust emission performance and combustion properties of neat and blended Gas-To-Liquids (GTL) diesel fuel are presented. A sulphur-free European diesel fuel was used as the reference fuel, and two blends of the GTL diesel fuel with the reference fuel, containing 20% and 50% GTL diesel fuel respectively, were investigated. The study was based on a Mercedes Benz 2.2 liter passenger car diesel engine and presents emission data for both the standard engine calibration settings, as well as settings which were optimized to match the characteristics of each fuel. Vehicle emission tests showed that the GTL diesel fuel results in reductions in HC and CO emissions of greater than 90%, while PM is reduced by 30%, and NOx remains approximately unchanged. Engine bench dynamometer tests showed reductions in soot of between 30% and 60%, and NOx reductions of up to 10% with the GTL diesel fuel, depending on the operating point.

This paper addresses the use of neat, indigenous biodiesel in advanced Mercedes-Benz passenger cars. Modern, unmodified EU3 Common-Rail diesel engines with second generation common rail technology were used to determine the effects of neat biodiesel on performance and emission characteristics. The biodiesel was made from the seeds of the Jatropha Curcas plant and sourced from the Central Salt and Marine Chemicals Research Institute in Bhavnagar, India. The production of biodiesel and the vehicle tests are part of a PPP project, funded jointly by the DaimlerChrysler AG and the German DEG. The project aims at providing additional jobs and income in rural Indian areas along with reclaiming unused wasteland. The test vehicles were operated for a cumulative 8000 kilometers with an intention to expose the vehicle and fuel to diverse climatic conditions.

In a subproject of the aim to develop a worldwide certification procedure for heavy-duty on-highway engines (WHDC), the measuring technique for future low emitting engines was evaluated. One aspect is the introduction of partial flow dilution systems for the particulates measurement during transient test cycles instead of the currently required full flow dilution systems. This paper presents an investigation about the influence of sensitive sampling parameters on particulate mass and composition under steady state and transient engine operating conditions, and their effect on the correlation between partial flow and full flow dilution systems. The study has shown that the sampling parameters investigated have no or only minor influence on particulate mass and composition. Both partial flow dilution systems proved their transient capability by tracking the exhaust flow signal very well.

For the measurement of exhaust emissions, Constant Volume Sampling (CVS) technology is recommended by legislation and has proven its practical capability in the past. However, the introduction of new low emission standards has raised questions regarding the accuracy and variability of the CVS system when measuring very low emission levels. This paper will show that CVS has the potential to achieve sufficient precision for certification of SULEV concepts. Thus, there is no need for the introduction of new test methods involving high cost. An analysis of the CVS basic equations indicates the importance of the Dilution Factor (DF) for calculating true mass emissions. A test series will demonstrate that, by adjusting the dilution and using state of the art analyzers, the consistency of exhaust results is comparable with those of LEV concepts, measured with conventional CVS systems and former standard analyzers.