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GTL (Gas-To-Liquid) fuel is well known to improve tailpipe emissions when fuelling a conventional diesel vehicle, that is, one optimized to conventional fuel. This investigation assesses the additional potential for GTL fuel in a GTL-dedicated vehicle. This potential for GTL fuel was quantified in an EU 4 6-cylinder serial production engine. In the first stage, a comparison of engine performance was made of GTL fuel against conventional diesel, using identical engine calibrations. Next, adaptations enabled the full potential of GTL fuel within a dedicated calibration to be assessed. For this stage, two optimization goals were investigated: - Minimization of NOx emissions and - Minimization of fuel consumption. For each optimization the boundary condition was that emissions should be within the EU5 level. An additional constraint on the latter strategy required noise levels to remain within the baseline reference.

The growing availability of different biofuels and synthetic fuels is leading to increased diversity of automotive fuels. Understanding how fuel properties affect combustion and how engine calibration strategies can compensate for variations in fuel composition is crucial for ensuring proper engine operation in this world of increased fuel diversity. This study looks at the ability to compensate for wide changes in cetane quality. Four different fuels with variations in cetane number, volatility and composition have been tested in a single cylinder engine and compared to diesel fuel. The selected operating conditions represent the entire engine map of a passenger car diesel engine. In part load the effects were investigated for conventional and premixed Diesel combustion. The results show that part load operation is especially relevant for the detection and compensation of varying fuel properties and that, depending on engine load, different control strategies have to be applied.

Partly competing objectives, as low fuel consumption, low friction, long oil maintenance rate, and at the same time lowest exhaust emissions have to be fulfilled. Diminishing resources, continuously reduced development periods, and shortened product cycles yield detailed knowledge about oil consumption mechanisms in combustion engines to be essential. There are different ways for the lubricating oil to enter the combustion chamber: for example as blow-by gas, leakage past valve stem seals, piston rings (reverse blow-by) and evaporation from the cylinder liner wall and the combustion chamber. For a further reduction of oil consumption the investigation of these mechanisms has become more and more important. In this paper the influence of the mixture formation and the resulting fuel content in the cylinder liner wall film on the lubricant oil emission was examined.

The steady increase of engine power and the demand of lightweight design along with enhanced reliability require an optimized dimensioning process, especially in cylinder head valve bridge, which is progressively prone to cracking. The problems leading to valve bridge cracking are high temperatures and temperature gradients on one hand and high mechanical restraining on the other hand. The accurate temperature estimation at the valve bridge center has significant outcomes for valve bridge thickness and width optimization. This paper presents a 1D heat transfer model, which is constructed through the cross section of the valve bridge center by the use of well known quasi-stationary heat convection and conduction equations and reduced from 3D to 1D via regression and empirical weighting coefficients. Several diesel engine cylinder heads with different application types and materials are used for model setup and verification.

Fatty Acid Methyl Ester (FAME) products derived from vegetable oils and animal fats are now widely used in European diesel fuels and their use will increase in order to meet mandated targets for the use of renewable products in road fuels. As more FAME enters the diesel pool, understanding the impact of higher FAME levels on the performance and emissions of modern light-duty diesel vehicles is increasingly important. Of special significance to Well-to-Wheels (WTW) calculations is the potential impact that higher FAME levels may have on the vehicle's volumetric fuel consumption. The primary objective of this study was to generate statistically robust fuel consumption data on three light-duty diesel vehicles complying with Euro 4 emissions regulations. These vehicles were evaluated on a chassis dynamometer using four fuels: a hydrocarbon-only diesel fuel and three FAME/diesel fuel blends containing up to 50% v/v FAME. One FAME type, a Rapeseed Methyl Ester (RME), was used throughout.

With the start of Euro 6d regulations, gasoline particulate filters (GPF) have become standard equipment in European vehicles with gasoline-direct-injection engines. GPFs will also be broadly applied to meet the upcoming China 6 regulations. An existing challenge with GPFs is accurate soot load detection to manage the pressure loss across the exhaust system and to protect the GPFs from soot overload, which could potentially cause damage as result of uncontrolled soot oxidations. Systems with the GPF located in the under-floor position have a higher potential risk of soot overload due to lower temperatures, which can result in higher soot accumulation rates. The accuracy of existing soot estimation methods such as evaluation of the pressure drop of the soot-loaded GPF or model-based balancing of soot accumulation versus soot oxidation rates are sensitive to transient operating condition of a vehicle.

The share of gasoline engines based on direct injection (DI) technology is rapidly growing, to a large extend driven by their improved efficiency and potential to lower CO2 emissions. One downside of these advanced engines are their significantly higher particulate emissions compared to engines based on port fuel injection technologies [1]. Gasoline particulate filters (GPF) are one potential technology path to address the EU6 particulate number regulation for vehicles powered by gasoline DI engines. For the robust design and operation of GPFs it is essential to understand the mechanisms of soot accumulation and oxidation under typical operating conditions. In this paper we will first discuss the use of detailed numerical simulation to describe the soot oxidation in particulate filters under typical gasoline engine operating conditions. Laboratory experiments are used to establish a robust set of soot oxidation kinetics.

Regulated emissions, CO2-values, comfort, good driveability, high reliability and costs, this is the main frame for all future powertrain developments. In this frame, the diesel powertrain, not only for passenger cars, but also for commercial vehicle applications, faces some challenges in order to fulfil the future European and current US emission legislations while keeping the fuel consumption benefit, good driveability and an acceptable cost frame. One of these challenges is the varying fuel qualities of diesel fuel in different countries including different cetane number, volatility, sulphur content and different molecular composition. In addition to that in the future, more and more alternative fuels with various fuel qualities and properties will be launched into the market for economical and environmental reasons. At present, the control algorithms of the injection system applied in most diesel engines is open loop control.

Diesel particulate filters are expected to be used on most passenger car applications designed to meet coming European emission standards, EU5 and EU6. Similar expectations hold for systems designed to meet US Tier 2 Bin 5 standards. Among the various products oxide filter materials, such as cordierite and aluminum titanate, are gaining growing interest due to their unique properties. Besides the intrinsic robustness of the filter products a well designed operating strategy is required for the successful use of filters. The operating strategy is comprised of two elements: the soot estimation and the regeneration strategy. In this paper the second element is discussed in detail by means of theoretical considerations as well as dedicated engine bench experiments. The impact the key operating variables, soot load, exhaust mass flow, oxygen content and temperature, have on the conditions inside the filter are discussed.

Torque and performance requirements of Diesel engines are continually increasing while lower emissions and fuel consumption are demanded, thus increasing thermal and mechanical loads of the main components. The level of peak firing pressure is approaching 200 bar (even higher in Heavy Duty Diesel engines), consequently, a structural optimization of crankcase, crank train components and in particular of the cylinder head is required to cope with the increasing demands. This report discusses design features of cylinder head concepts which have the capability for increasing thermal and mechanical loads in modern Diesel engines

Diesel particulate filters are becoming a standard for most light duty diesel applications designed for European EU5 and EU6 regulations. Oxide based filter materials are continuing to gain significant interest and have been in high volume serial application since 2005. Compared to carbide materials they show some unique properties. With respect to the design, the length of a filter is a key variable. Usually the prime design consideration is the desired filter volume. The diameter or frontal area is then usually defined by packaging constraints. Finally, the length is adapted. The paper provides experimental data on the impact this key design parameter has on the pressure drop and the thermal behavior under “worst case” regeneration conditions. A wide range of soot loads (from 4 g/dm3 to 9 g/dm3) as well as filter lengths from 6″ to 12″ is considered and evaluated under comparable experimental conditions.

Within a public founded project test cell investigations were undertaken to identify parameters which predominantly influence the development of critical deposits in injection nozzles. A medium-duty diesel engine was operated in two different coking cycles with a zinc-free lubricant. One of the cycles is dominated by rated power, while the second includes a wide area of the operation range. During the experiments the temperatures at the nozzle tip, the geometries of the nozzle orifice and fuel properties were varied. For a detailed analysis of the deposits methods of electron microscopy were deployed. In the course of the project optical access to all areas in the nozzle was achieved. The experiments were evaluated by means of the monitoring of power output and fuel flow at rated power. The usage of a SEM (scanning electron microscope) and a TEM (transmission electron microscope) revealed images of the deposits with a magnification of up to 160 000.

Current progress in the development of diesel engines substantially contributes to the reduction of NOx and Particulate Matter (PM) emissions but will not succeed to eliminate the application of Diesel Particulate Filters (DPFs) in the future. In the past we have introduced a Multi-Functional Reactor (MFR) prototype, suitable for the abatement of the gaseous and PM emissions of the Low Temperature Combustion (LTC) engine operation. In this work the performance of MFR prototypes under both conventional and advanced combustion engine operating conditions is presented. The effect of the MFR on the fuel penalty associated to the filter regeneration is assessed via simulation. Special focus is placed on presenting the performance assessment in combination with the existing differences in the morphology and reactivity of the soot particles between the different modes of diesel engine operation (conventional and advanced). The effect of aging on the MFR performance is also presented.

It is the objective of this work to characterize mixture formation in the sprays emanating from Multi-Layer (ML) nozzles under approximately engine-like conditions by quantitative, spatially, and temporally resolved fuel-air ratio and temperature measurements. ML nozzles are cluster nozzles which have more than one circle of orifices. They were introduced previously, in order to overcome the limitations of conventional nozzles. In particular, the ML design yields the potential of variable spray interaction, so that mixture formation could be controlled according to the operating condition. In general, it was also a primary aim of the cluster-nozzle concepts to combine the enhanced atomization and pre-mixing of small nozzle holes with the longer spray penetration lengths of large holes. The applied diagnostic, which is based on 1d spontaneous Raman scattering, yields the quantitative stoichiometric ratio and the temperature in the vapor phase.

Improved fuel economy is a key measure of performance in the automotive industry, driven both by market demand and increasingly stringent government emissions regulations. In this climate, targeting even small benefits to fuel consumption (FC) can have a large impact when considering fleet average CO2 emissions. Lubricant properties over the course of an oil drain interval (ODI) directly influence long-term fuel consumption. Furthermore, viscosity control gasoline additives have been shown to provide FC benefit via fuel-to-lubricant transfer. This study investigated whether consistently fueling with gasoline containing friction modifier (FM) additives could provide a long-term fuel consumption benefit via a lubricant transfer mechanism. A robust fleet trial method was employed to quantify fuel consumption benefits of two friction modifier additive packages relative to a baseline deposit control additive (DCA) package in a 95 RON, E5 fuel.

It is expected that the world's energy demand will double by 2050, which requires energy-efficient technologies to be readily available. With the increasing number of vehicles on our roads the demand for energy is increasing rapidly, and with this there is an associated increase in CO₂ emissions. Through the careful use of optimized lubricants it is possible to significantly reduce vehicle fuel consumption and hence CO₂. This paper evaluates the effects on fuel economy of high quality, low viscosity heavy-duty diesel engine type lubricants against mainstream type products for all elements of the vehicle driveline. Testing was performed on Shell's driveline test facility for the evaluation of fuel consumption effects due to engine, gearbox and axle oils and the variation with engine operating conditions.

Previous work has shown that it may be advantageous to use gasoline type fuels with long ignition delays compared to today's diesel fuels in compression ignition engines. In the present work we investigate if high volatility is also needed along with low cetane (high octane) to get more premixed combustion leading to low NO and smoke. A single-cylinder light-duty compression ignition engine is run on four fuels in the diesel boiling range and three fuels in the gasoline boiling range. The lowest cetane diesel boiling range fuel (DCN = 22) also has very high aromatic content (75%vol) but the engine can be run on this to give very low NO (≺ 0.4 g/kWh) and smoke (FSN ≺ 0.1), e.g,. at 4 bar and 10 bar IMEP at 2000 RPM like the gasoline fuels but unlike the diesel fuels with DCNs of 40 and 56. If the combustion phasing and delay are matched for any two fuels at a given operating condition, their emissions behavior is also matched regardless of the differences in volatility and composition.

Controlled Auto Ignition combustion systems have a high potential for fuel consumption and emissions reduction for gasoline engines in part load operation. Controlled auto ignition is initiated by reaching thermal ignition conditions at the end of compression. Combustion of the CAI process is controlled essentially by chemical kinetics, and thus differs significantly from conventional premixed combustion. Consequently, the CAI combustion process is determined by the thermodynamic state, and can be controlled by a high amount of residual gas and stratification of air, residual gas and fuel. In this paper both fundamental and application relevant aspects are investigated in a combined approach. Fundamental knowledge about the auto-ignition process and its dependency on engine operating conditions are required to efficiently develop an application strategy for CAI combustion.

In this study the fuel influence of several bio-fuel candidates on homogeneous engine combustion systems with direct injection is investigated. The results reveal Ethanol and 2-Butanol as the two most knock-resistant fuels. Hence these two fuels enable the highest efficiency improvements versus RON95 fuel ranging from 3.6% - 12.7% for Ethanol as a result of a compression ratio increase of 5 units. Tetrahydro-2-methylfuran has a worse knock resistance and a decreased thermal efficiency due to the required reduction in compression ratio by 1.5 units. The enleanment capability is similar among all fuels thus they pose no improvements for homogeneous lean burn combustion systems despite a significant reduction in NOX emissions for the alcohol fuels as a consequence of lower combustion temperatures.

Catalytic converter substrates for automobile emission control have to operate under the hostile conditions of the automotive exhaust. This paper will first discuss the mechanical and physical properties to ensure durable mechanical function of the catalytic substrate and converter system. High temperature mechanical and thermal shock substrate requirements and properties will be discussed. The functionality of a catalytic converter is significantly influenced by the catalytic coating. At the same time, substrate characteristics as will be shown, also effect converter functional parameters like back pressure, light-off and conversion efficiency. The importance of the substrate parameters cell shape, cell density and substrate mass and their effect on thermohydraulic parameters like heat- and mass transfer factors for various cell structures and substrates will be presented.