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Dual-fuel engines are recognized as a short-medium term solution to reduce fuel consumption and pollutant emissions of CI engines, while maintaining high energy efficiency. Methane (CH4) was chosen as it offers the best compromise between its heating value and H/C ratio. The high auto-ignition temperature of CH4 requires auto-igniting a small quantity of liquid diesel before it initiates the combustion of the mixture. Therefore, new engine operations need to be specifically developed. This investigation explores the impact of time sequences of injection of the liquid fuel on the ignition of homogenous methane/air mixture. Experiments were performed on a Rapid Compression Expansion Machine (RCEM), to reproduce the operating and dynamic conditions encountered in a diesel engine cycle, allowing visualizations of fuel injection and combustion processes through a transparent piston.

One 4-stroke scooter and two 2-stroke scooters (50 cc bore) were run on dynamic test benches according to the EC47 driving cycle. Emissions from these scooters were continuously monitored, sampled and hot- diluted prior being driven to continuous flow through chambers containing organotypic cultures of lung tissue under bi-phasic Air/liquid culture conditions for three hours. Lung tissue was evaluated for viability (ATP), anti-oxidant defenses (intracellular GSH, Catalase, superoxide-dismutases, glutathione-S-Transferase, glutathione peroxidase, glutathione-reductase activity levels) and inflammatory reaction through the measurement of TNFalpha secretion in the culture medium. 4-stroke engine emissions had a moderate impact on lung tissue viability but induced a marked GSH depletion concomitant of increased GPx activity. 2-strokes engine emissions had variable impacts according to after-treatment technology and lube oil quality.

European regulations have made the use of diesel particulate filter (DPF) unavoidable because all future diesel vehicles have to comply with the Euro 5 regulation regarding particulate matter emissions. Indeed, DPF has an overall excellent filtering efficiency but should be periodically regenerated. We propose here an in vitro comparative toxicological study of diluted sampled exhaust, emitted during legislative NEDC (New European Driving Cycle) cycles with or without a DPF regeneration phase. Pollutants, particle sizing, ESR (Electron Spin Resonance) measurement and post-exposure biological evaluation were monitored. Only TNFα (Tumor Necrosis Factor alpha), a biological molecule produced during inflammatory processes, was slightly induced for the highest exhaust concentration including regeneration phase. In conclusion, it appears that regeneration process does not induce an acute toxicity.

Future engine control systems need suitable and accurate models for combustion. For this purpose, this paper presents a practical application of nonlinear autoregressive moving average polynomial models with exogenous inputs (NARMAX) technique to model pressure dynamics inside the cylinder of a direct injection compression ignition engine. Two models have been investigated taking two different sets of input variables. The first model only includes basic injection settings available from the electronic control unit. The second model uses the instantaneous crankshaft revolution speed as a main model input. Model parameter identification and validation are performed with experimental data obtained from a test engine equipped with a piezoelectric pressure sensor and with data computed from a thermodynamic-based engine cycle simulation code.

At the end of four years Research & Development programme, the bench test results for the MCE-5 VCR engine are presented. Downsized supercharged Variable Compression Ratio engines allow for a 30% fuel consumption reduction while providing high power and torque and opening the way to numerous pollutants emissions reduction strategies. In this context, piston to crankshaft transmission by means of gears gives new opportunities for future mass production of rigid and robust low friction engines that conform to VCR requirements while improving piston and rings operation. Through development programmes, the MCE-5 gear-based compression ratio control device proved its robustness and reliability, as well as its ability to allow the design of compact and efficient VCR engines which are easy to integrate into all vehicles.

To provide fuel/air ratio quantitative measurements in an S.I engines, a transparent cylinder engine is investigated with the Fuel-Air Ratio Laser Induced Fluorescence (FARLIF) technique. In a homogeneous mixture, the two dimensional distribution for the fuel/air ratio is calibrated and measured during the compression stroke for different equivalence ratios. After spark ignition, the combustion zone and the flame front are visualized by laser sheet LIF. The direct-injection stratified-charge, new concept for gasoline engines is investigated with FARLIF. In the direct injection gasoline engine where the fuel is directly injected into a cylinder and the flow is highly turbulent, two injection timings are used: -early injection (i.e. during the intake stroke) to promote a homogeneous distribution; -late injection during the compression stroke, to generate a ultra-lean stratified charge.

The reduction of Particulate emission from diesel engines is one of the most important diesel exhaust emission problems and the use of Diesel Particulate Filter (DPF) appears essential for meeting future legislation. The Direct Injection turbo-charged diesel engine is characterized by low exhaust gas temperature and requires the use of an additive catalyst to allow soot combustion in the DPF. Diesel particulate filter combined with additive are now commonly studied by car manufacturers. Presently suppliers propose different additives which are not easy to evaluate. The aim of this work is to propose a new evaluation method of the capability of different additives. Usually the additive performance for trap regeneration is assessed through the measurement of a single criterion: ignition temperature. This temperature depends on different parameters linked to exhaust gas and particulate filter properties.

Precision-cut rat lung slices in organotypic culture, placed in a biphasic air/liquid system, are used for this study. This model allows to realize pathological and histochemical studies as well as cell and molecular biology investigations. Slices are exposed to a continuous flow of diluted diesel exhausts, with a pO2 regulated at 20% in order to avoid hypoxia-induced effects. The exposure system allows to study concomitantly five exhaust concentrations coming from the same diesel engine, and also to evaluate the impact of particulate matter using a filter placed on the exposition vials. Precision lung slices are exposed for three or six hours to a whole or filtered diesel engine exhaust.

Organotypic cultures of precision-cut rat lung slices are exposed three hours to 5 dilutions of a continuous exhaust flow. The exhausts from three fuelings are tested (filtered and not): gazole, gazole/RME mixture (70 % / 30%) and RME. Different parameters are assessed: ATP and GSH (cell viability), TNFα production (proinflammatory response) and nucleosomes (apoptosis). After exposure, the ATP level is only modified by the highest concentrations of gazole/RME or RME exhausts (filtered and not); the GSH level is decreased for each of the concentrated filtered exhausts. Moreover, only the whole gazole exhaust leads to a modification of TNFα production. At last, the whole gazole exhaust leads to an increase of slice nucleosome level in a dose-dependent way; RME supplementation or filtration significantly attenuates this effect.