Impact of aircraft fuel chemical composition on the physicochemical properties of primary and secondary particulate matter emissions

International audienc

The UNREAL (Unveiling nucleation mechanism in aircraft engine exhaust and its link with fuel composition) project: Results from simulation chamber and reactor experiments

International audienceAviation emissions are not limited to greenhouse gases like CO2 but include other gases as well, such as nitrogen oxides (NOx) or sulfur oxides (SOx) and volatile and non-volatile particulate matter (vPM and nvPM respectively). Sulfuric acid formed in the engine exhaust seems to be linked to the formation of vPM. However, the amount of sulfur present in the fuel converted to sulfuric acid in the exhaust is too small to explain the amount of vPM observed and organic species seem to play a key role in their formation. The UNREAL project aims at studying at the molecular level the different mechanisms of new particle formation from the exhausts of aircraft engines fed by different fuels. We used a Combustion Aerosol STandard (CAST) generator especially designed to work with liquid fuel to generate the emissions from different fuels (from the standard Jet A-1 to 100% Sustainable Aviation Fuel (SAF). Total, or only gas-phase, emissions were injected in both, an atmospheric simulation chamber (CESAM) and a Potential Aerosol Mass Oxidation Flow Reactor (PAM-OFR) for aging. Both systems used in parallel provide a point of comparison between in near-real time and hours-long time chamber aging approaches. The chemical and physical evolution of primary and secondary CAST emissions, were monitored by different instruments to measure particle number, mass concentrations as well their size distribution, and the chemical composition of both, the particulate and gas phases. In addition to online techniques, samples were collected to study off line, the gas and aerosol chemical composition at molecular level by mass spectrometry

Impact of fuel composition on primary and secondary aeronautic emissions: gaseous and particulate chemical characterization at molecular level

International audienceOne of the actual concerns of aviation industry is to reduce its impact on climate and air quality using for example Sustainable Aviation Fuels (SAF, [1]). As part of the UNREAL Project [2], the objective of this work was to study and compare chemically, at a molecular level, gaseous and particulate phases of primary and secondary emissions from various aircraft fuels, from the standard Jet A-1 to 100 % SAF (Alcohol to Jet). Related emissions from a liquid CAST burner [3] were injected into an atmospheric chamber (CESAM), and in parallel, into a Potential Aerosol Mass Oxidation Flow Reactor (PAM-OFR) to age the emissions (OH reactivity in both cases). To collect these fresh and aged particles, a system with two quartz fiber filters was used: the Front Filter (FF) traps the particulate phase while the Back Filter (BF) is coated with activated carbon to retain the gas phase [4]. Samples were analyzed with a Two-Step Laser Mass Spectrometry (L2MS) technique to study the chemical composition of emissions, in particular Polycyclic Aromatic Compounds (PAC) and sulfur such as SO2, SO3 or H2SO4. The chemical composition of the filter-deposited samples is compared to on-line measurements performed by an Aerosol Mass Spectrometer and an Aerosol Chemical Speciation Monitor for particles, and a Proton Transfer Reaction Mass Spectrometer (PTRMS) for gaseous species. A comparison of the primary and aged emission molecular chemical fingerprints obtained, as well as between both atmospheric reactors (CESAM vs PAM-OFR), will be proposed. This work benefited from the support of the project UNREAL ANR-18-CE22-0019 of the French National Research Agency (ANR)

Development of coupled optical techniques for the measurements of soot and precursors in laboratory flame and aero-engine technical combustors

International audienceThis work is focused on the development of planar in-situ laser-based methods serving for the mapping of soot precursors and soot particles in hash combustion conditions. We target the soot molecular precursors and particulates because there are still unanswered questions related to the mechanisms leading to the formation of soot particles and their quantification in harsh combustion conditions. Laser-induced incandescence (LII) at 1064 nm is coupled with laserinduced fluorescence (LIF) at 532 nm to monitor soot and its precursors, respectively, on the MICADO test rig. A progressive approach is followed to implement the optical techniques, where LII/LIF is first tested and evaluated in a laminar diffusion flame, stabilized on a coflow burner at atmospheric pressure. Measurements of soot volume fraction and soot precursors are reported in combustion conditions similar to the cruise cycle in terms of total mass flow rate and pressure into the combustor

Laser-induced incandescence and fluorescence for in-situ characterization of soot particles and precursors in semi-technical aeronautic combustors

National audiencePhysical and chemical properties of soot emitted from airplanes are still poorly known due to the difficult access at the core of these systems, as well as the stringent conditions into or at the exhaust of the engines. It is challenging to directly measure soot particles inside aeronautic combustors due to the high pressure and limited optical access. Under these harsh combustion conditions, we try to identify the mechanisms participating in the formation of soot particles. These mechanisms are still subject to numerous questions due to the lack of experimental evidence and high demand for processing power requested by theoretical models. The solution to this problem relies on the coordinated efforts of researchers for the implementation of experimental and theoretical tools. To overcome the experimental challenges, this work focuses on the development and implementation of laser induced incandescence (LII), a technique used for the detection of soot volume fraction, as well as laser induced fluorescence (LIF), a technique used for the characterization of soot precursors

Liquid Combustion Aerosol Standard Generator (CAST): a low-cost alternative combustion emission source for aeronautical fuel evaluation

International audienceEmissions from aircraft engines impact climate and air quality in and around airports (Airbus GMF 2018, Vorster et al. 2013). There are different options available to reduce aircraft emissions, based notably on the development of sustainable fuels. The evaluation of the physicochemical characteristics of the particulate emissions from such fuels in real conditions is difficult to achieve and very expensive. The mini-CAST burner, suitable for the combustion of liquid fuel (Jing 2003), is an interesting alternative to obtain soot emissions comparable to those from aircraft engine. The design of the liquid CAST is based on the conventional propane model but here, the propane flame is used to vaporize the fuel in the combustion chamber to further generate a flame. A quenching flow of nitrogen stops the combustion reactions and a flow of dilution air accelerates emissions in the measurement line and avoids soot agglomeration. This work aimed to characterize CAST emissions for aircraft fuels of different chemical compositions and to study their stability and reproducibility

Liquid Combustion Aerosol Standard Generator (CAST): a low-cost alternative combustion emission source for aeronautical fuel evaluation

International audienceEmissions from aircraft engines impact climate and air quality in and around airports (Airbus GMF 2018, Vorster et al. 2013). There are different options available to reduce aircraft emissions, based notably on the development of sustainable fuels. The evaluation of the physicochemical characteristics of the particulate emissions from such fuels in real conditions is difficult to achieve and very expensive. The mini-CAST burner, suitable for the combustion of liquid fuel (Jing 2003), is an interesting alternative to obtain soot emissions comparable to those from aircraft engine. The design of the liquid CAST is based on the conventional propane model but here, the propane flame is used to vaporize the fuel in the combustion chamber to further generate a flame. A quenching flow of nitrogen stops the combustion reactions and a flow of dilution air accelerates emissions in the measurement line and avoids soot agglomeration. This work aimed to characterize CAST emissions for aircraft fuels of different chemical compositions and to study their stability and reproducibility

Liquid Combustion Aerosol Standard Generator (CAST): a low-cost alternative combustion emission source for aeronautical fuel evaluation

International audienceEmissions from aircraft engines impact climate and air quality in and around airports (Airbus GMF 2018, Vorster et al. 2013). There are different options available to reduce aircraft emissions, based notably on the development of sustainable fuels. The evaluation of the physicochemical characteristics of the particulate emissions from such fuels in real conditions is difficult to achieve and very expensive. The mini-CAST burner, suitable for the combustion of liquid fuel (Jing 2003), is an interesting alternative to obtain soot emissions comparable to those from aircraft engine. The design of the liquid CAST is based on the conventional propane model but here, the propane flame is used to vaporize the fuel in the combustion chamber to further generate a flame. A quenching flow of nitrogen stops the combustion reactions and a flow of dilution air accelerates emissions in the measurement line and avoids soot agglomeration. This work aimed to characterize CAST emissions for aircraft fuels of different chemical compositions and to study their stability and reproducibility

Liquid Combustion Aerosol Standard Generator (CAST): a low-cost alternative combustion emission source for aeronautical fuel evaluation

International audienceEmissions from aircraft engines impact climate and air quality in and around airports (Airbus GMF 2018, Vorster et al. 2013). There are different options available to reduce aircraft emissions, based notably on the development of sustainable fuels. The evaluation of the physicochemical characteristics of the particulate emissions from such fuels in real conditions is difficult to achieve and very expensive. The mini-CAST burner, suitable for the combustion of liquid fuel (Jing 2003), is an interesting alternative to obtain soot emissions comparable to those from aircraft engine. The design of the liquid CAST is based on the conventional propane model but here, the propane flame is used to vaporize the fuel in the combustion chamber to further generate a flame. A quenching flow of nitrogen stops the combustion reactions and a flow of dilution air accelerates emissions in the measurement line and avoids soot agglomeration. This work aimed to characterize CAST emissions for aircraft fuels of different chemical compositions and to study their stability and reproducibility