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Finite fossil energy sources and carbon dioxide as a main cause for climate changes are still under critical discussion. Therefore, scientists work on the replacement of fossil by alternative diesel fuels from biomass. Hence, in this study the in-cylinder combustion and particle number emissions of di-n-butyl ether (DNBE), as a representative of second generation biofuels, and of reference diesel fuel (B0) for comparison were analyzed by several measurement techniques at different injection and boost pressures. The heat release rate and thus the ignition delay as well as the center of combustion were analyzed by monitoring the global in-cylinder pressure signal using a pressure sensor. The combustion process was also visualized by simultaneous imaging of the hydroxyl radical and a spectral range of soot luminescence. This allows the analysis of the in-cylinder soot formation and oxidation process.

In recent years, there has been rapid progress in characterizing the detailed chemical kinetics associated with the oxidation of liquid hydrocarbons and their blends. However adding these fuel models to the industrial engineer's toolkit has proven a major challenge due to issues associated with high CPU cost and the poor suitability of many of the most promising and well known fuel models to IC engine applications. This paper demonstrates the state-of-the-art in the analysis and modelling of current and future transportation fuels or fuel blends for internal combustion engine applications. First-of-all, a benchmarking of eleven representative fuel models (39 to 1034 species in size) is carried out at engine/engine-like operating conditions by adopting the standard Research Octane and Cetane Number test data for comparison. Next, methods to construct a fuel model for a commercial fuel are outlined using a simple, yet robust surrogate mapping technique.

This paper describes the influence of diesel engine operating parameters not only on the properties of the emitted soot particles but also on the whole engine chain of events, which was visualized by optical measurement techniques. The vapor and liquid phase of the injected diesel spray was observed simultaneously by laser-induced exciplex florescence (LIEF) to analyze mixture formation up to the visible start of combustion. The soot formation and oxidation process was evaluated by detecting a spectral range of the soot luminescence and the OH radical. The electrical mobility particle diameter as well as the primary particle size of the emitted soot particles were analyzed by a Scanning Mobility Particle Sizer (SMPS) and by High-Resolution Transmission Electron Microscopy (HR-TEM).

This work capitalizes on the investigation of the effect of injection pressure and timing on the in-cylinder soot formation performance of low CR GTL-fueled DI diesel engine. An optically-accessed Rapid Compression Machine capable of simulating compression and expansion strokes of diesel engine was deployed allowing the application of optical diagnostics. For the detection of flame zones aiming mainly at determining the Lift-Off-Length, imaging of flame self-luminescence technique was used, while for the assessment of in-cylinder soot formation the photodiode-based non-imaging soot incandescence acquisition optical technique has been applied. Through in-cylinder installed pressure transducer and piston position sensor, the rate of heat release was calculated for the analysis of the combustion development. It was found that soot formation rate and peak decrease with increasing injection pressure. The former decreases, however, non-linearly, while the later decreases linearly.