Luminescence properties and scintillation mechanisms of Ce3+Ce^ {3+} - , Pr3+Pr^ {3+} - and Nd3+Nd^ {3+} - doped lutetium pyrosilicate

International audienc

High Efficiency of Lutetium Silicate Scintillators, Ce-Doped LPS and LYSO Crystals for Medical Applications

International audienc

Use of Ethanol/Diesel Blend and Advanced Calibration Methods to Satisfy Euro 5 Emission Standards without DPF

The use of biofuels has been extensively developed in the last years to diversify energy resources and to participate to the transportation greenhouse gas emissions reduction effort. One of the most promising renewable fuels for large scale production is the ethanol which is nowadays mainly used for spark-ignited engines; nonetheless the European market share of Diesel vehicles is around 60%. These issues lead us to propose an innovative fuel formulation using ethanol for Diesel engine applications. The key issues to deal with the use of ethanol in a Diesel blend are the miscibility, the flashpoint, the lubricity and the cetane number. An intensive work has been done to optimise the formulation coupling the use of ethanol, with first and second generations of Diesel biofuels. The application on a Euro 4-compliant Diesel turbocharged engine with high pressure exhaust gas recirculation shows an outstanding decrease of particulate matter emissions thanks to this oxygenated fuel. Nevertheless unburned hydrocarbons and carbon monoxide emissions could be an issue as well as NOx emissions if the engine control settings are not updated. Combustion analysis helps understanding the fuel effect on the resulting auto-ignition delay and the pilot injection combustion behaviour, which leads to modified engine output compared to Diesel fuel. Therefore, the optimisation of the fuel/engine matching is performed using advanced calibration methodologies combined with design of experiments at the engine test bed. First of all, global and mixed approaches are proposed and compared in warm operating conditions. Finally it permits to simultaneously drop nitrogen oxides emissions and particulate matter emissions. Global CO2 emissions reduction and noise decrease are also expected. To further investigate engine emissions potential reduction, the engine is set up on a dynamic test bed facility, allowing to reproduce cold New European Driving Cycle (NEDC). Several innovative calibration methods, based on the simultaneous optimisation of engine basic settings and cold correction maps, are introduced in order to better suit to the new formulation impact on combustion and catalyst light-off and to drop off engine-out unburned hydrocarbons and carbon monoxide emissions. This stage allows pushing forward the work on test bed facilities in order to reduce the amount of vehicle tests. Tests on a chassis dynamometer are only used to validate the engine test bed results and to perform final tuning of cold correction maps. This alternative blend shows potential to achieve Euro 5 standard with Euro 4 Diesel vehicle configuration, without any hardware modification and without a Diesel particulate filter in the exhaust line. Such an innovative fuel formulation seems to be an interesting answer to the trade-off in the forthcoming years between cost and emissions reduction to achieve sustainable mobility. The presented calibration methods and tools allow to fully take advantage of this alternative fuel in a reduced time scale

Optical properties and energy levels of Ce3+Ce^ {3+} in lutetium pyrosilicate scintillator crystal

International audienceCerium doped lutetium pyro-silicate Ce3+:Lu2Si2O7 (LPS) is an inorganic scintillator that displays particularly promising performance. The spectroscopic properties of pure and Ce3+-doped Lu2Si2O7 are investigated. X-ray-excited luminescence, time-resolved excitation and emission spectroscopy, as well as decay time spectra are presented. For better understanding of the scintillation mechanism, several approaches were undertaken to locate the Ce3+ energy levels relative to levels of LPS host. To estimate the energy position of Ce3+ 4f levels with respect to the valence band, x-ray photoemission spectroscopy (XPS) was used. Scintillation properties of LPS: Ce are explained in terms of the relative positions of Ce3+-5d levels and the conduction band

Experimental and Numerical Study of F-T/Biodiesel/Bioethanol Surrogate Fuel Oxidation in Jet-Stirred Reactor

International audienc