44 research outputs found
On the response of semitransparent nanoparticulated films of LuPO4:Eu in poly-energetic X-ray imaging applications
Luminescence properties and scintillation mechanisms of - , - and - 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 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