Letteratura scientifica selezionata sul tema "Volatile (vPM) and non-Volatile (nvPM) Particulate Matter"

The contribution of aircraft operations to ambient ultrafine particle (UFP) concentration at and around airports can be significant. This review article considers the volatile and non-volatile elements of particulate matter emissions from aircraft engines, their characteristics and quantification and identifies gaps in knowledge. The current state of the art emission inventory methods and dispersion modelling approaches are reviewed and areas for improvement and research needs are identified. Quantification of engine non-volatile particulate matter (nvPM) is improving as measured certification data for the landing and take-off cycle are becoming available. Further work is needed: to better estimate nvPM emissions during the full-flight; to estimate non-regulated (smaller) engines; and to better estimate the emissions and evolution of volatile particles (vPM) in the aircraft exhaust plume. Dispersion modelling improvements are also needed to better address vPM. As the emissions inventory data for both vPM and nvPM from aircraft sources improve, better estimates of the contribution of aircraft engine emissions to ambient particulate concentrations will be possible.

The aviation sector, like most other sectors, is moving towards becoming net zero. In the medium to long term, this will mean an increase in the use of sustainable aviation fuels. Research exists on the impact of fuel composition on non-volatile particulate matter (nvPM) emissions. However, there is more sparsity when considering the impact on volatile particulate matter (vPM) emissions. Here, nine different fuels were tested using an open-source design combustor rig. An aerosol mass spectrometer (AMS) was used to examine the mass-loading and composition of vPM, with a simple linear regression algorithm used to compare relative mass spectrum similarity. The diaromatic, cycloalkane and aromatic contents of the fuels were observed to correlate with the measured total number concentration and nvPM mass concentrations, resulting in an inverse correlation with increasing hydrogen content. The impacts of fuel properties on other physical properties within the combustion process and how they might impact the particulate matter (PM) are considered for future research. Unlike previous studies, fuel had a very limited impact on the organic aerosol’s composition at the combustor exit measurement location. Using a novel combination of Positive Matrix Factorization (PMF) and high-resolution AMS analysis, new insight has been provided into the organic composition. Both the alkane organic aerosol (AlkOA) and quenched organic aerosol (QOA) factors contained CnH2n+1, CnH2n−1 and CnH2n ion series, implying alkanes and alkenes in both, and approximately 12% oxygenated species in the QOA factor. These results highlight the emerging differences in the vPM compositional data observed between combustor rigs and full engines.

Abstract. Sustainable aviation fuels (SAFs) have different compositions compared to conventional petroleum jet fuels, particularly in terms of fuel sulfur and hydrocarbon content. These differences may change the amount and physicochemical properties of volatile and non-volatile particulate matter (nvPM) emitted by aircraft engines. In this study, we evaluate whether comparable nvPM measurement techniques respond similarly to nvPM produced by three blends of SAFs compared to three conventional fuels. Multiple SAF blends and conventional (Jet A-1) jet fuels were combusted in a V2527-A5 engine, while an additional conventional fuel (JP-8) was combusted in a CFM56-2C1 engine. We evaluated nvPM mass concentration measured by three real-time measurement techniques: photoacoustic spectroscopy, laser-induced incandescence, and the extinction-minus-scattering technique. Various commercial instruments were tested, including three laser-induced incandescence (LII) 300s, one photoacoustic extinctiometer (PAX), one micro soot sensor (MSS+), and two cavity-attenuated phase shift PMSSA (CAPS PMSSA) instruments. Mass-based emission indices (EIm) reported by these techniques were similar, falling within 30 % of their geometric mean for EIm above 100 mg per kg fuel (approximately 10 µg PM m−3 at the instrument); this geometric mean was therefore used as a reference value. Additionally, two integrative measurement techniques were evaluated: filter photometry and particle size distribution (PSD) integration. The commercial instruments used were one tricolor absorption photometer (TAP), one particle soot absorption photometer (PSAP), and two scanning mobility particle sizers (SMPSs). The TAP and PSAP were operated at 5 % and 10 % of their nominal flow rates, respectively, to extend the life of their filters. These techniques are used in specific applications, such as on board research aircraft to determine particulate matter (PM) emissions at cruise. EIm reported by the alternative techniques fell within approximately 50 % of the mean aerosol-phase EIm. In addition, we measured PM-number-based emission indices using PSDs and condensation particle counters (CPCs). The commercial instruments used included TSI SMPSs, a Cambustion differential mobility spectrometer (DMS500), and an AVL particle counter (APC), and the data also fell within approximately 50 % of their geometric mean. The number-based emission indices were highly sensitive to the accuracy of the sampling-line penetration functions applied as corrections. In contrast, the EIm data were less sensitive to those corrections since a smaller volume fraction fell within the size range where corrections were substantial. A separate, dedicated experiment also showed that the operating laser fluence used in the LII 300 laser-induced incandescence instrument for aircraft-engine nvPM measurement is adequate for a range of SAF blends investigated in this study. Overall, we conclude that all tested instruments are suitable for the measurement of nvPM emissions from the combustion of SAF blends in aircraft engines.

Abstract. A new regulatory standard for non-volatile particulate matter (nvPM) mass-based emissions from aircraft engines has been adopted by the International Civil Aviation Organisation. One of the instruments used for the regulatory nvPM mass emissions measurements in aircraft engine certification tests is the Artium Technologies LII 300, which is based on laser-induced incandescence. The LII 300 response has been shown in some cases to vary with the type of black carbon particle measured. Hence it is important to identify a suitable black carbon emission source for instrument calibration. In this study, the relationship between the nvPM emissions produced by different engine sources and the response of the LII 300 instrument utilising the auto-compensating laser-induced incandescence (AC-LII) method was investigated. Six different sources were used, including a turboshaft helicopter engine, a diesel generator, an intermediate pressure test rig of a single-sector combustor, an auxiliary power unit gas turbine engine, a medium-sized diesel engine, and a downsized turbocharged direct-injection gasoline engine. Optimum LII 300 laser fluence levels were determined for each source and operating condition evaluated. It was found that an optimised laser fluence can be valid for real-time measurements from a variety of sources, where the mass concentration was independent of laser fluence levels covering the typical operating ranges for the various sources. However, it is important to perform laser fluence sweeps to determine the optimum fluence range as differences were observed in the laser fluence required between sources and fuels. We discuss the measurement merits, variability, and best practices in the real-time quantification of nvPM mass concentration using the LII 300 instrument and compare that with other diagnostic techniques, namely absorption-based methods such as photoacoustic spectroscopy (using a photoacoustic extinctiometer, PAX, and a micro soot sensor, MSS) and thermal-optical analysis (TOA). Particle size distributions were also measured using a scanning mobility particle sizer (SMPS). Overall, the LII 300 provides robust and consistent results when compared with the other diagnostic techniques across multiple engine sources and fuels. The results from this study will inform the development of updated calibration protocols to ensure repeatable and reproducible measurements of nvPM mass emissions from aircraft engines using the LII 300.

Abstract. Around 5 % of anthropogenic radiative forcing (RF) is attributed to aviation CO2 and non-CO2 impacts. This paper quantifies aviation emissions and contrail climate forcing in the North Atlantic, one of the world's busiest air traffic corridors, over 5 years. Between 2016 and 2019, growth in CO2 (+3.13 % yr−1) and nitrogen oxide emissions (+4.5 % yr−1) outpaced increases in flight distance (+3.05 % yr−1). Over the same period, the annual mean contrail cirrus net RF (204–280 mW m−2) showed significant inter-annual variability caused by variations in meteorology. Responses to COVID-19 caused significant reductions in flight distance travelled (−66 %), CO2 emissions (−71 %) and the contrail net RF (−66 %) compared with the prior 1-year period. Around 12 % of all flights in this region cause 80 % of the annual contrail energy forcing, and the factors associated with strongly warming/cooling contrails include seasonal changes in meteorology and radiation, time of day, background cloud fields, and engine-specific non-volatile particulate matter (nvPM) emissions. Strongly warming contrails in this region are generally formed in wintertime, close to the tropopause, between 15:00 and 04:00 UTC, and above low-level clouds. The most strongly cooling contrails occur in the spring, in the upper troposphere, between 06:00 and 15:00 UTC, and without lower-level clouds. Uncertainty in the contrail cirrus net RF (216–238 mW m−2) arising from meteorology in 2019 is smaller than the inter-annual variability. The contrail RF estimates are most sensitive to the humidity fields, followed by nvPM emissions and aircraft mass assumptions. This longitudinal evaluation of aviation contrail impacts contributes a quantified understanding of inter-annual variability and informs strategies for contrail mitigation.

Abstract. Aviation emissions that are dispersed into the Earth's atmosphere affect the climate and air pollution, with significant spatiotemporal variation owing to heterogeneous aircraft activity. In this paper, we use historical flight trajectories derived from Automatic Dependent Surveillance–Broadcast (ADS-B) telemetry and reanalysis weather data for 2019–2021 to develop the Global Aviation emissions Inventory based on ADS-B (GAIA). In 2019, 40.2 million flights collectively travelled 61 billion kilometres using 283 Tg of fuel, leading to CO2, NOX and non-volatile particulate matter (nvPM) mass and number emissions of 893 Tg, 4.49 Tg, 21.4 Gg and 2.8 × 1026 respectively. Global responses to COVID-19 led to reductions in the annual flight distance flown and CO2 and NOX emissions in 2020 (−43 %, −48 % and −50 % respectively relative to 2019) and 2021 (−31 %, −41 % and −43 % respectively), with significant regional variability. Short-haul flights with durations < 3 h accounted for 83 % of all flights but only for 35 % of the 2019 CO2 emissions, while long-haul flights with durations > 6 h (5 % of all flights) were responsible for 43 % of CO2 and 49 % of NOX emissions. Globally, the actual flight trajectories flown are, on average, ∼ 5 % greater than the great circle path between the origin and destination airports, but this varies by region and flight distance. An evaluation of 8705 unique flights between London and Singapore showed large variabilities in the flight trajectory profile, fuel consumption and emission indices. GAIA captures the spatiotemporal distribution of aviation activity and emissions and is provided for use in future studies to evaluate the negative externalities arising from global aviation.

Abstract Estimating non-volatile Particulate Matter (nvPM) - or black carbon - emissions during an aircraft mission is extremely challenging, because of the lack of reliable data in flight. For this reason, a detailed study has been undertaken to estimate in-flight emissions from data measured on the ground during engine certification. Aircraft engine emissions certification is based on the "Landing and Take-Off" (LTO) cycle. The aim of this regulation is to control emissions in the vicinity of the airport (below 3000ft). New certification standards on nvPM have been introduced recently. With these regulations, manufacturers are now reporting nvPM emissions data publicly. All emissions data of in-production engines are available in the engine emissions data bank (EEDB), downloadable from the European Union Aviation Safety Agency (EASA) website. Methodologies have been proposed to estimate emissions at altitude and calculate total mission emissions for NOx, which are only relying on these publicly available data from the EEDB. In the following, a new methodology for estimating nvPM emissions at altitude is proposed. The methodology was developed and validated in the framework of the CAEP technical working groups. It comprises four dedicated steps. In the present article, the different steps are explained and validation data is provided as applicable. Examples of in-production engines are analyzed, discussed, and compared against the full methodology using proprietary engine performance and emissions certification data. Following the proposed methodology, total nvPM mass and number mission emissions can be estimated and used for emissions inventories and evaluation of climate impacts.

L'une des préoccupations actuelles de l'industrie aéronautique est la diminution de la consommation de carburant et de l'empreinte environnementale. En effet, les émissions aéronautiques ont un impact sur la qualité de l'air et notamment au niveau des zones aéroportuaires. Comme d'autres secteurs du transport, le trafic aérien génère des gaz à effet de serre (2 % du total dans le monde), des traînées de condensation ainsi que des particules volatiles et non volatiles (vPM et nvPM).Pour réduire ces émissions, différentes approches ont été pensées avec en particulier l'usage de carburants aéronautiques durables (SAF - Sustainable Aviation Fuels). L'objectif des SAF est de réduire les émissions nettes de CO2 et de nvPM. Cependant, la combustion de ces carburants peut entraîner la formation de nouveaux polluants qui réagissent avec l'atmosphère en formant des aérosols secondaires (SA). Dans le cadre du projet UNREAL (Unveiling Nucleation mechanism in aiRcraft Engine exhAust and its Link with fuel composition), l'objectif de ce travail était d'étudier les différents mécanismes au niveau moléculaire à l'origine de la formation de nouvelles particules à partir des rejets moteurs alimentés par des carburants de compositions différentes, allant du Jet A-1 standard à du carburant 100 % SAF.La caractérisation physico-chimique des émissions en conditions réelles en sortie moteur est un défi à la fois d'un point de vue technique et économique. Pour pallier à cela un brûleur mini-CAST, adapté à la combustion de carburants liquides aéronautiques, a été utilisé comme alternative pour obtenir des émissions comparables, dans une certaine mesure, à celles des moteurs aéronautiques. Une diminution des émissions de nvPM (concentration en nombre, concentration en masse et distribution de tailles) peut être observée en corrélation avec la quantité de composés aromatiques présents dans le carburant. De plus, l'analyse par spectrométrie de masse a révélé une diminution de l'intensité relative des HAP lors de l'emploi de carburants alternatifs. Les émissions du brûleur ont été injectées, avec ou sans filtration des suies, dans une chambre atmosphérique de vieillissement (chambre CESAM reproduisant les conditions atmosphériques au niveau du sol - LISA). Pour tous les carburants testés, la formation de vPM par nucléation homogène a été observée dans la chambre atmosphérique en l'absence de nvPM. Ce phénomène est particulièrement prononcé pour les carburants comprenant de grandes quantités de soufre dans leur composition. Cependant, dans les cas réels (présence de suies), la formation de vPM n'est observée que pour les carburants contenant de fortes quantités de soufre. La concentration de précurseurs gazeux formés pour les autres carburants n'est pas suffisante pour produire des vPM, notamment avec l'adsorption des gaz à la surface des particules de suies (nucléation hétérogène). Les techniques de caractérisation en ligne ont été complétées par des prélèvements sur filtre et une analyse par spectrométrie de masse, mettant en évidence la présence de HAP, d'hydrocarbures oxygénés, de composés soufrés et azotés. En utilisant des méthodes semi-quantitatives, il a été possible de mettre en relation la composition chimique (intensité relative de soufre et de HAP) avec la formation de vPM et leur répartition dans les phases particulaires et gazeuses des émissions
One of the actual concerns of the aviation industry is to reduce fuel consumption and environmental footprint. Indeed, aviation emissions impact air quality in and around airports. As other transport sectors, aviation effluents need to be addressed to reduce greenhouse gases contribution (2% of these emissions are related to air transport worldwide), volatile and non-volatile Particulate Matter (vPM and nvPM) and indirect impact as condensation trails.To reduce these emissions, different approaches have been investigated, in particular the use of Sustainable Aviation Fuels (SAF). Aims of SAF are to decrease the net CO2 emissions and nvPM. However, combustion of these fuels may lead to new pollutants that can react with atmosphere by formation of secondary aerosols. As part of the UNREAL project (Unveiling Nucleation mechanism in aiRcraft Engine exhAust and its Link with fuel composition), the objective of this work was to study the different molecular mechanisms of new particle formation from the exhausts of aircraft engines fed by fuels with different composition, from the standard Jet A-1 to 100 % SAF fuel.The physicochemical characterisation of the particulate emissions from aircraft engines in real conditions is challenging both from the technical and economical point of view. Thus, a mini-CAST burner, suitable for the combustion of aeronautic liquid fuels, has been used as an alternative to obtain emissions comparable to some extent to those from aircraft engines. A decrease in nvPM emissions (number concentration, mass concentration and size distribution) can be observed in correlation with the quantity of aromatic compounds in the fuel. Moreover, the analysis by mass spectrometry revealed a decrease in the relative intensity of PAHs when alternative fuels were employed . Emissions from the burner have been injected, with and without soot filtration, into an atmospheric chamber for ageing (CESAM chamber reproducing atmospheric conditions at ground level - LISA). For all fuels tested formation of vPM by homogeneous nucleation has been observed in the atmospheric chamber in absence of nvPM. This phenomenon is particularly highlighted for fuels with high amounts of sulphur in their compositions. However, in real cases (presence of soot), the formation of vPM is only observed for the fuels containing high amounts of sulphur. The concentration of gaseous precursors formed for other fuels was not enough to produce vPM after being adsorbed on soot surface (heterogeneous nucleation). On-line characterisation techniques were completed by filter sampling and off-line mass spectrometry analysis, highlighting the presence of PAHs, oxygenated hydrocarbons, sulphur and nitrogen compounds. By employing semi-quantitative methods, it was possible to link the relative chemical composition (sulphur and PAH relative intensity) with vPM formation and their repartitions in particulate and gaseous phases

Aircraft engines are a source of harmful non-volatile Particulate Matter (nvPM) emissions, negatively affecting human health and the global environment. To mitigate this, new sources of fuel are being assessed for the commercial aviation sector. Sustainable Aviation Fuels (SAF) show significant promise as replacements to conventional aviation fuels, with the potential to reduce lifecycle CO2 and nvPM emissions because of lower aromatic contents and higher hydrogen content. Towards better understanding of the nvPM emissions from aircraft combustors operating with SAF, this work outlines results from the RAPTOR experimental test campaigns performed at Cardiff University’s Gas Turbine Research Centre (GTRC). Several aviation fuels of varying physiochemical properties were burned in a non-proprietary Rich-Quench-Lean (RQL) combustor rig. The nvPM emissions were measured using the European nvPM reference system, with data corrected for particle loss in the sampling and measurement system using additional particle size measurement. nvPM emission reductions were achieved for fuels of higher hydrogen content, and system loss correction was required to accurately quantify those reductions. Additionally, independent control of the air supply to the combustor rig allowed the impact of fuel spray quality to be decoupled from AFR, demonstrating that small improvements in spray droplet atomisation predicted from benchmarking fuel spray experiments (~5% reduction in SMD) consistently yielded significant reductions in nvPM emissions, ranging from 5-72% for nvPM EImass, 11-89% for nvPM EInumber, and 1-7% for GMD.

Abstract To address the known Local Air Quality impacts of ultrafine combustion derived soot, the International Civil Aviation Organisation (ICAO) have recently adopted a non-volatile Particulate Matter (nvPM) regulation in addition to those of NOx, UHC’s and CO for civil aviation gas turbines. Increased water humidity is known to reduce the formation of NOx in flames through localised temperature reduction, however its impact on emitted nvPM is to date not clearly understood. To address this knowledge gap, nvPM formation mechanisms were assessed empirically at increasing water loadings both at atmospheric pressure — in a RQL representative optical combustor fuelled with Jet A and alternative fuel blends — and during a full-scale Rolls-Royce aero-derivative Gas Turbine test fuelled on Diesel. In line with previous studies, in the RQL combustor rig it was observed that increased hydrogen content in the test fuel — associated with a 100% Gas-To-Liquid (GTL) derived aviation kerosene with low aromatic content (0.05%) — reduced nvPM number concentrations by an order of magnitude compared to a baseline Jet A-1 fuel with representative aromatic content (24.24%). For all fuels tested it was also observed that an elevated water loading in the primary combustion zone (≤ 0.05 kg /kg of dry air), representative of maximum global humidity levels, resulted in reductions of both nvPM number and mass concentrations of 40% and 60% respectively. During a full-scale Rolls-Royce gas turbine study similar trends were observed, with an 85% reduction in measured nvPM mass whilst water was injected into the combustor at flow rates 25% higher than the diesel fuel flow. The nvPM reductions in both experiments are significantly larger than can be explained by water dilution effects alone, with less impact noted for fuels with higher hydrogen content. This suggests the reduction may be in part due to chemistry. Preliminary chemical kinetic investigations were undertaken using CHEMKIN-PRO and suggest that the soot reduction mechanism is potentially via a reduction in PAH formation within the flame zone. However, further analysis is required to validate if this mechanism is dominated by in-flame OH reduction mechanisms or influenced significantly by other factors associated with water dilution and reduced flame temperatures.

Abstract Estimating non-volatile Particulate Matter (nvPM) — or black carbon — emissions during an aircraft mission is extremely challenging because of the lack of reliable data in flight. For this reason, a detailed study has been undertaken to estimate in-flight emissions from data measured on the ground during engine certification. Aircraft engine emissions certification is based on the “Landing and Take-Off” (LTO) cycle developed by the Committee on Aviation Environmental Protection (CAEP) of the International Civil Aviation Organization (ICAO). It represents operations below 3000ft. The aim of this regulation is to control and reduce pollutant emissions in the vicinity of the airport. Carbon monoxide (CO), unburnt hydrocarbon (UHC), and Nitrogen oxides (NOx) have been regulated using the LTO cycle by different international standards for four decades. New certification standards on nvPM have been introduced recently. The first one, put in place in CAEP10, regulates the peak nvPM mass concentration. It has been in effect since 2020. The second set established in CAEP11 regulates the nvPM mass and number emissions on the LTO cycle and it becomes effective in 2023. With these regulations, manufacturers are now reporting nvPM emissions data publicly. All emissions data of in-production engines, and some legacy engines, are available in the engine emissions data bank (EEDB), downloadable from the European Union Aviation Safety Agency (EASA) website [1]. Methodologies have been proposed to estimate emissions at altitude and calculate total mission emissions for NOx, i.e. the “Boeing Fuel Flow Method” [2] or the “DLR Döpelheuer and Lecht” [3–5] methodology, which are only relying on these publicly available data from the EEDB. In the following, a new methodology for estimating nvPM emissions at altitude is proposed. The methodology was developed and validated in the framework of the CAEP technical working groups. It comprises four dedicated steps. In the present article, the different steps are explained and validation data is provided as applicable. Examples of in-production engines are analyzed, discussed, and compared against the full methodology using proprietary engine performance and emissions certification data. Following the proposed methodology, total nvPM mass and number mission emissions can be estimated and used for emissions inventories and evaluation of climate impacts.

Abstract The measurement and reporting of non-volatile Particulate Matter (nvPM) emissions is now integral to aircraft engine emission certification. Akin to other gaseous emissions, CAEP11 sets a new LTO based standard. So far, the question how nvPM emission can be corrected for ambient conditions has to remain open. Addressing this, combustor rig tests may be consulted, where performance parameter such as Air-to-fuel ratio, pressure and temperature can be varied independently. However, results from selected tests may be misleading as nvPM emissions may show measurement uncertainties within actual sensitivities. The paper provides a novel approach utilising experimental data to investigate the prevailing sensitivities at different operation conditions and derive applicable correction factors. This methodology makes use of the fundamental assumption that each change measured in nvPM emissions is explainable with the relative change in combustor AFR, the combustion chamber inlet pressure P3, and combustor inlet temperature T3, for a given combustor design running on the same fuel. Computing the relative changes between all measurements of the same test for all performance and emission parameters enables the fitting of a nonlinear regression model to the experimental data. The fitted function consists of the product of the relative change of the performance parameters to the power of polynomial exponents. The methodology has the potential to be applied to a wide variation of emissions data obtained from different sources as combustor rig tests as well as from engine emission tests. The paper concludes with a first application of the methodology to experimental engine emissions data and a short discussion on AFR sensitivity. In order to set-up a more broadly applicable model nvPM pathways and mechanisms and their dependencies must be better understood helping to identify relevant parameters, e.g. characteristic AFR in the nearfield of the fuel spray nozzle.