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Faire son stage de Master au laboratoire

To reduce fuel consumption, Greenhouse Gases, NOx and soot particles emissions,recent developments in engine technology have focused on operating internal combustionengines at lower temperatures and fuel concentrations. These constraints have motivatedthe apparition of Exhaust Gas Recirculation (EGR) technology, and triggered interest in Low-Temperature Combustion (LTC) engines. In these conditions, combustion chemistry is more complex as it relies on the formation of peroxides. Chemical branching is degenerate and highlyfuel-specific. To accommodate the use of modern fuels such as biodiesels or fuels produced from biomass, predictive models of this combustion chemistry must be constructed and validated.

Recently, the interest has grown on the use of liquid fuels produced from lignocellulosic biomass.Because of the presence of heteroatoms (O, N) in their chemical structure, specific reaction pathways can be observed, rendering the utilization of typical rate rules for the prediction of rate coefficients difficult. However, dedicated tools for the exploration of potential energy surfaces, such as Kinbot, have been developed. This tool allows the automation of the calculation of the transition states and products for a given reactive system. The purpose of thiswork will be the implementation of the Kinbot code on the University’s HPC cluster, and its use toinvestigate the complex reactive systems relative to novel biofuels. Specifically identified rate constants will be determined with help from quantum chemistry calculations at a high levelof theory.

Keywords: Pollutant reduction, combustion, kinetic modeling, ab initio

Laboratory: PC2A

Supervisor: FENARD Yann

Tél : 03.20.43.48.04, E-mail: yann.fenard[chez]univ-lille[point]fr

Co-supervisors:                VANHOVE Guillaume, LOUIS Florent

CaPPA Work Package:     WP-1 From gas phase to aerosols

Considering the environmental costs of manufacturing, running and disposing of electric vehicles, the opportunity to use internal combustion engines fueled with hydrogen is much more realistic than expecting a nearly immediate global uptake of electric vehicles. Governments are putting strategic plans in motion to decrease primary energy use, take carbon out of fuels and facilitate modal shifts. Taking a prominent place in these strategic plans is hydrogen as a future energy carrier. A number of manufacturers are now leasing demonstration vehicles to consumers using hydrogen-fueled internal combustion engines. This dual-fuel application shows a decrease of NOx, smoke, CO and unburnt hydrocarbons emissions.
However, fundamental studies on the hydrogen process affecting the low temperature combustion kinetics of carbon fuels are scarce, especially with oxygenated fuels produced from biomass. Low temperature combustion kinetics are initiated by the interaction of fuel-originated primary radicals and molecular oxygen, leading to an increase of the reactivity in the temperature range 650-800 K. It affects the operation of internal combustion engines, and ultimately their efficiency and pollutant emissions.
A global parameter is widely used for the characterization of a fuel: the ignition delay time (IDT). It describes the time required for a fuel/air mixture to ignite under known conditions of temperature and pressure. The study of the IDT allows the formulation of fuels and the optimization of fuel/air equivalence ratio required for an optimal performance of an engine.
During this internship, we propose the measurement of the IDT of different fuels mixed with H2 depending on the chemical nature of the fuel – alkane, alkene, alcohol or ketone – to cover the potential chemicals that could be found in fossil fuels or biofuels. The facility used at PC2A is a rapid compression machine. This facility compresses the fuel / air mixture within 45 ms to pressures up to 25 bar heating the mixture to temperatures of 600 and 900 K. It is a temperature range allowing the study of the low-temperature kinetics of combustion. The analysis of results will make it possible to draw a trend in the interaction of chemical functions with H2.
Keywords: Hydrogen, biofuels, ignition delay times, pollutants, combustion

Laboratory: PC2A

Supervisor: FENARD Yann

Tél : 03.20.43.48.04, E-mail: yann.fenard[chez]univ-lille[point]fr

Co-supervisor:                VANHOVE Guillaume

CaPPA Work Package:     WP-1 From gas phase to aerosols

The future of combustion engines is dependent on significant reduction in pollutant emissions, as well as improvement in fuel efficiency and substantial reduction in fuel consumption. Controlled initiation of the combustion is a crucial step towards these goals, with wide ranges of application including piston engines, constant volume combustors, gas turbines and aeronautic engines. In all these cases, reproducible initiation of the combustion phase is sought, multipoint or volumetric ignition being preferred. However, fuel ignition is highly dependent on the chemical kinetics associated with Low Temperature Combustion (LTC).

The chemical mechanisms relevant to LTC include the formation of unstable peroxides, the structure of which reflects the initial fuel. The reactivity of a fuel in this temperature regime is therefore highly constrained by its structure. This is also true for next generation biofuels, whose oxidation pathways can be strongly different from “traditional” fossil fuels. To facilitate ignition of such fuels, ozone-seeding has been suggested as a practical and easy solution.

To investigate the potential of this technology, a burner dedicated to the study of stabilized cool flames has been designed and validated. The potential to perform detailed kinetic studies through a number of optical and analytical diagnostics has been demonstrated, including Planar Laser Induced Fluorescence (PLIF), chemiluminescence and gas chromatographic techniques. These data can be used to validate kinetic models of the LTC chemistry under these rarely investigated conditions.

As part of this work, the panel of diagnostics associated to the burner will be extended to flow-field characterization optical techniques, as well as techniques dedicated to the detection of unstable species, such as VUV photoionization mass spectrometry.

Laboratory: PC2A

Supervisor: VANHOVE Guillaume

Tél : 03.20.43.44.85, E-mail: guillaume.vanhove[chez]univ-lille[point]fr

Co-supervisor:                PILLIER Laure

CaPPA Work Package:     WP-1 From gas phase to aerosols

Les Masters en cours