Andreas Kolbeck

Dedicated GTL Vehicle: A Calibration Optimization Study

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 • Minimization of fuel consumption

Advanced diesel combustion

Future emission norms will further reduce the vehicle emissions of diesel engines. To meet the goal of achieving these stringent limits while maintaining attractive attributes of marketability, the combustion system needs also to be revised or redesigned in order to achieve the CO2 limits that will be demanded in the future, while simultaneously producing significantly reduced untreated NO2 emissions. In the scope of this article, the basic conditions for the design of future combustion systems shall be discussed. As a possible solution, we will introduce the FEV combustion system HECS (High Efficiency Combustion System), with which very low fuel consumption can be obtained even at high part loads, while producing minimal nitrogen oxides.

Glow-plug Ignition of Ethanol Fuels under Diesel Engine Relevant Thermodynamic Conditions

The requirement of reducing worldwide CO 2 emissions and engine pollutants are demanding an increased use of bio-fuels. Ethanol with its established production technology can contribute to this goal. However, due to its resistive auto-ignition behavior the use of ethanol based fuels is limited to the spark ignited gasoline combustion process. For application to the compression ignited Diesel combustion process advanced ignition systems are required. In general, ethanol offers a significant potential to improve the soot emission behavior of the Diesel engine due to its oxygen content and its enhanced evaporation behavior. In this contribution the ignition behavior of ethanol and mixtures with high ethanol content is investigated in combination with advanced ignition systems with ceramic glow-plugs under Diesel engine relevant thermodynamic conditions in a high pressure and temperature vessel. The investigation focuses on optimizing the injection conditions, especially injection pressure and rate. Optical measurements are performed by high speed imaging of the fuel injection and ignition, and evaluated in terms of ignition and flame propagation. The high speed imaging technology furthermore enables to gain information on the statistical behavior of the ignition process and thus provides a direct assessment of the repeatability of the ignition and combustion process. The results of the ignition investigation aim at improving the understanding of the glow-plug induced ignition process in order to provide a reliable ignition strategy for the Diesel engine operation with fuel with high ethanol content. The results show that the favorable spray targeting relative to the glow-plug depends on the glow-plug design. Furthermore a moderate injection pressure improves the ignition reliability of the ethanol fuels. The latter leads to the hypothesis that reduced injection induced shear rates improve the ignition behavior by diminishing shear induced quenching in the ignition zone in the direct vicinity of the hot glow-plug surface.

Tailor Made Biofuels: Effect of Fuel Properties on the Soot Microstructure and Consequences on Particle Filter Regeneration

In recent years a lot of effort has been made to understand the phenomena of Diesel Particulate Filter (DPF) regeneration processes but less attention has been paid to understand the influence of fuel properties on soot reactivity and its consequence on the DPF regeneration behavior.Within the Cluster of Excellence “Tailor-Made Fuels from Biomass (TMFB)” at RWTH Aachen University, the Institute for Combustion Engines carried out a detailed investigation program to explore the potential of future biofuel candidates for optimized combustion systems. These new biofuels are being developed to realize partially homogeneous low-temperature combustion, in order to reduce the emission and fuel consumption to meet future requirements. The chemical structure of these new fuels may impact the thermal decomposition chemistry and hence the in-cylinder particulate formation conditions. This work fundamentally focusses the influence of fuel properties on particulate matter reactivity and, thereby, the regeneration behavior of the diesel particulate filters (DPF).The experiments for particulate measurements and analysis were conducted, under constant engine operating conditions, on a EURO 6 compliant High Efficiency Combustion System (HECS) fuelled with petroleum based diesel fuel as baseline and today’s biofuels like FAME and Fischer Tropsch fuels as well as potential biomass derived fuel candidates being researched in TMFB.Several different methods were used for analysis of mass, composition, structure and spectroscopic parameters of the soot. The graphitic microstructure visible with high resolution transmission electron microscopy (HRTEM) was compared to the results of X-Ray diffraction (XRD), optical light absorption measurement and elementary analysis of samples.The results indicate that combustion with increasing fuel oxygenation produces decreasing engine-out particulate emissions. The ranking of activation energies of soot oxidation analysis from LGB experiments correspond well with the ranking of the soot physico-chemical properties. In comparison to petroleum based diesel fuel, the reduction of engine out soot emission by a factor of five with the use of the future biomass derived fuel candidate was accompanied by ten times reduction of the soot volume based absorption coefficient and two times reduction of carbon to hydrogen ratio. As a result of it, the activation energy of soot oxidation in DPF reduced by ∼ 10 KJ/mol. The reduced engine out soot emission and increased reactivity of the soot from the future biomass derived fuel candidate could cause a significant reduction of thermal DPF regenerations.Copyright

Biodiesel Effects on Engine and Emission Control Systems

Raising interest in Diesel powered passenger cars in the USA in combination with the government mandated policy to reduce dependency of foreign oil, leads to the desire of operating Diesel vehicles with biodiesel fuel blends. There is only limited information related to the impact of biodiesel fuels on the performance of advanced emission control systems. In this project the implementation of a NOx storage and an SCR emission control system and the development for optimal performance were evaluated by FEV.