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Internal short circuits in lithium-ion batteries; origins, detection, and experimental reproduction: A review
No full textInternational audienceInternal short circuits constitute a significant risk to the safety and performance of lithium-ion batteries (LiBs). Internal short circuits are among the most problematic failure mechanisms in LiBs because of their ability to cause thermal runaway and catastrophic failure and inherent difficulty of detection. This review provides a comprehensive overview of the types of internal short circuits, their origins, and the experimental methods used to reproduce them. Firstly, the definition and classification of internal short circuits, as well as their associated consequences from minor performance loss to thermal runaway, are described. Secondly, the root causes of internal short circuits are investigated, including a thorough examination of each manufacturing stage where defects can appear, focusing on preventive measures. Finally, the review details experimental approaches to reproduce internal short circuits mentioning their respective advantages and drawbacks with a focus on mechanical internal short circuit reproduction devices, such as nail/needle penetration techniques. These techniques are the easiest to implement but have an important number of variable parameters that can influence the test outcome
Exploitation des six premières années de données automatiques du programme CARA (Composition chimique des PM, 2015-2021)
No full textThis report summarizes the results obtained from the study of the chemical composition of fine particulate matter (PM) and organic aerosol (OA) sources at 13 French urban sites in the CARA Program of the Laboratoire Central de Surveillance de la Qualité de l'Air (LCSQA) for the period 2015-2021. This work was carried out as part of a PhD thesis funded by the LCSQA.Over this period, mean annual PM1 concentrations ranged from 7 (in Rennes) to 16 µg m-3 (in Paris-Boulevard Périphérique Est; BPEst), with a mean level of around 10 (± 8) µg m-3 for the 14 sites studied. The results obtained clearly indicate the dominance of OA (40-60 %) within this size class, particularly for the highest PM1 concentration levels, underlining the influence of biomass combustion during winter pollution episodes, but also the impact of secondary organic aerosol (SOA) formation in summer, especially for sites in central and southern France (Marseille, Poitiers, Talence and Lyon) under the effect of more intense photochemical processes. Conversely, the relative contributions of nitrate (NO3, 25-30 %) are more pronounced at sites in the northern half of France (ATOLL, Creil, Gennevilliers, etc.), due to meteorological conditions more favorable to the maintenance of ammonium nitrate in the particulate phase, which plays an important role during springtime pollution episodes.The analysis of OA sources showed the existence of common factors between the different measurement sites (stations), including primary factors, linked mainly to emissions from traffic and biomass combustion, and secondary oxygenated factors. Other specific factors (e.g. cooking activities, emissions linked to industrial activities and/or shipping) were also identified at certain sites. Generally, oxygenated factors dominate the OA (66 %), confirming the importance of ageing and secondary formation processes. Nevertheless, an increase in the contribution of the factor directly linked to biomass combustion (BBOA) was observed for the highest winter concentrations of OA, also confirming the major role played by this source on PM levels in the urban background.These results can help guide policies aimed at improving air quality, contribute to improving model accuracy, and feed into future epidemiological studies. While automobile exhaust emissions are set to continue falling over the coming years, wood heating is likely to remain a major source of carbonaceous aerosols in France/Europe. The continuation of automatic observations within the CARA program will also provide input for studies aimed at gaining a better understanding of the impacts of climate change on the formation conditions of secondary aerosols (organic and inorganic).Finally, the various French datasets resulting from this work are of great importance to different partner scientific communities sharing the objective of improving air quality and reducing pollutant emissions. In addition to their use in measurement-model comparison exercises, it could be interesting to consider epidemiological studies aimed at quantifying the effects of aerosols on health, also in connection with current work on the oxidizing potential of particulate matter (Daellenbach et al., 2020; Weber et al., 2021). Depending on the size of the agglomerations studied and the nature of the health data that can be compared with atmospheric measurements, time series of the order of 3 years may be sufficient for this type of analysis. In this respect, these data are already being shared and used as part of the European RI-URBANS project (2021-2025), which aims to address the challenges and societal needs associated with air quality in European cities, with a view to reducing air pollution through new strategies for assessing the impact of air pollution on citizens' health (https://riurbans.eu/).Le présent rapport synthétise les résultats obtenus lors de l’étude de la composition chimique des particules fines (PM) et des sources d’aérosol organique (AO) sur 13 sites urbains français du Programme CARA du dispositif national du Laboratoire Central de Surveillance de la Qualité de l’Air (LCSQA) pour la période 2015-2021. Ce travail a été réalisé dans le cadre d’une thèse de doctorat financée par le LCSQA.Sur cette période, les concentrations annuelles moyennes de PM1 varient globalement entre 7 (à Rennes) et 16 µg m-3 (à Paris-Boulevard Périphérique Est ; BPEst), avec un niveau moyen de l’ordre de 10 (± 8) µg m-3 pour les 14 sites étudiés. Les résultats obtenus indiquent clairement la domination de l’AO (40 à 60 %) au sein de cette classe de taille, en particulier pour les niveaux de concentrations de PM1 les plus élevés, soulignant l’influence de la combustion de la biomasse lors des épisodes de pollution en hiver, mais aussi l’impact de la formation d’aérosols organiques secondaire (AOS) en été, en particulier pour les sites du centre et du sud de la France (Marseille, Poitiers, Talence et Lyon) sous l’effet de processus photochimiques plus intenses. À l’inverse, les contributions relatives de nitrate (NO3, 25-30 %) sont plus prononcées sur les sites de la moitié nord (ATOLL, Creil, Gennevilliers, …), en raison de conditions météorologiques plus favorables au maintien du nitrate d’ammonium en phase particulaire, jouant un rôle important lors des épisodes de pollution printaniers.L'analyse des sources d’AO a montré l'existence de facteurs communs entre les différents sites de mesure (stations), comprenant les facteurs primaires, liés principalement aux émissions du trafic et de la combustion de biomasse, et les facteurs oxygénés secondaires. D’autres facteurs spécifiques (e.g., activités de cuisson, émissions liées aux activités industrielles et/ou au transport maritime) ont pu également être mis en évidence sur certains sites. D’une manière générale, les facteurs oxygénés dominent l’AO (66 %), confirmant l’importance des processus de vieillissement et de formation secondaire. Néanmoins, on observe une augmentation de la contribution du facteur directement lié à la combustion de biomasse (BBOA) pour les plus fortes concentrations hivernales d’AO, confirmant également le rôle majeur joué par cette source sur les niveaux de PM en fond urbain.L’ensemble de ces résultats peut aider à orienter les politiques visant à améliorer la qualité de l'air, contribuer à améliorer la précision des modèles, et alimenter de futures études d’expologie. Alors que la baisse des émissions à l’échappement automobile devrait se poursuivre dans les années à venir, le chauffage au bois restera probablement une source importante d'aérosols carbonés en France/Europe. La poursuite des observations automatiques au sein du programme CARA permettra également d’alimenter les études visant à mieux appréhender les impacts du dérèglement climatique sur les conditions de formation des aérosols secondaires (organiques et inorganiques).Enfin, les différents jeux de données français issus de ce travail revêtent une grande importance pour différentes communautés scientifiques partenaires partageant l'objectif d'améliorer la qualité de l'air et de réduire les émissions de polluants. Outre leur utilisation dans des exercices de comparaison mesures-modèles, il pourrait être intéressant d’envisager la réalisation d’études d’expologie pour quantifier l’exposition des populations aux particules et à leur composition chimique, ce qui permettrait d’alimenter des études épidémiologiques visant à évaluer leurs effets sur la santé, en lien également avec les travaux actuels sur le potentiel oxydant des particules (Daellenbach et al., 2020 ; Weber et al., 2021). Selon la taille des agglomérations étudiées et la nature des données sanitaires pouvant être mises en regard des mesures atmosphériques, des séries temporelles de l’ordre de 3 ans peuvent en effet s’avérer suffisantes à la réalisation de ce genre d’analyse. A ce titre, ces données sont d’ores et déjà partagées et utilisées dans le cadre du projet européen RI-URBANS (2021-2025), qui vise à relever les défis et les besoins sociétaux liés à la qualité de l'air dans les villes européennes afin d’y réduire la pollution de l'air à l’aide de nouvelles stratégies d'évaluation des impacts de la pollution de l'air sur la santé des populations (https://riurbans.eu/)
Evaluating Ammonia's Flammability and Explosion Hazards in Air and Oxygen at Elevated Conditions: Data Generation and Review According to the New European Standard
No full textInternational audienceMany industrial processes operate under non-atmospheric conditions, involving high pressure and temperaturein a variety of oxidising media. It is therefore essential to assess the potential for explosive atmospheres of(vapour)/oxidising gases under these conditions. Explosive limits depend on pressure, temperature and theoxidising environment, and are determined using a variety of methods. To standardise these practices, theEuropean standardisation committee CEN TC 305 has introduced a new method in 2022. The candidate for thisstudy was ammonia, a promising carbon-free energy carrier (green ammonia) with a low environmental impactbut which also presents challenges related to its manufacture and use. However, data on the flammability andexplosibility of ammonia is limited, particularly under non-atmospheric conditions. A review of these data ispresented in this document. The experimental part of this work aims to produce new data on the explosive limitsof ammonia and the explosion severity according to this new standard in oxygen at an initial pressure of 0.5MPa and at 200 °C. The main conclusions are as follows (1) the lower explosive limit remains around 10%vol,as proposed by Doring (1931), (2) the upper explosive limit reaches 93%vol under the conditions tested, (3) themaximum explosion pressure measured is 42 MPa (explosion ratio of 8.3), and (4) the maximum rate of pressurerise is 920 MPa.s-1. The application of the EN 17624 standardised method makes it possible to generate new,up-to-date data to improve our understanding of the safety limits of ammonia
Air cyclone samplers for assessing the toxicological potential of particulate matter: A case study in railway environments
No full textInternational audienceEvaluating the toxicological impact of atmospheric particulate pollution (aerosols) is challenging. Several parameters of sampling need to be controlled to provide reliable evaluations. Notably collecting sufficient sample mass and preserving sample properties from collection to testing (cells for in vitro tests, lung fluid for reactive oxygen species (ROS) activity) is key. Sampling on a filter is the most widely used approach, but it has a major limitation. The extraction of aerosols trapped in the filter still requires the use of solvent and/or sonication, that may modify the size and/or the composition of the sampled aerosols. Here we explore alternative methodologies with cyclone air samplers to minimize alterations to the properties of the sample by collecting aerosols in a cone. The results show that the use of sonication remains necessary with a dry cyclone (no liquid of collection), whereas the use of a liquid with a surfactant avoids this. The associated toxicological tests show that 10 min of sampling in a moving train is sufficient to discriminate stations based on aerosols-induced effects. Higher oxidative stress levels are observed in underground stations than in overground stations for the intracellular Reactive Oxygen Species (1.87 vs 1.31 exposed cells/control), dithiothreitol activity (0.12 vs 0.09 nmol min−1) and ascorbic acid activity (0.52 vs 0.03 nmol min−1). Cyclone sampling thus represents a promising method for collecting a sufficient mass of aerosols in a short duration and limiting the modification of their properties for direct toxicological evaluation
Biodegradability of commercially available cellulose-PLA based compostable food trays – Influence of usage and UV aging
No full textInternational audienceThis study aimed to assess the biodegradability and behavior of cellulose trays coated with PLA-based liners, marketed as compostable alternatives to non-biodegradable polyolefin trays. Three commercial trays were analyzed by NMR, FTIR and SEC, revealing that their liners contained two to four polymers. Furthermore, the time and temperature conditions to which the material is exposed prior to consumption may influence certain properties of these innovative cellulose-based trays, ultimately affecting their biodegradability. A usage protocol simulating real-life conditions was developed. Post-usage analysis revealed structural failures in the trays, while the relative polymer composition of the liners remained almost unchanged. In addition, the question of whether solar irradiation during time spent in the sun on the surface of various ecosystems, in the case of unintentional release, could also affect biodegradability was examined. Simulated environmental exposure by UV irradiation led to changes in the composition of some liners. Both aging processes appear to have a non significant effect on biodegradation. Interestingly, biodegradation studies indicated varying degradation level among the trays, despite their similar cellulose content. Trays biodegradation percentages ranged from 70 to just 40 % after 60 days. The biodegradation of the liners themselves was lower, ranging from 30 % to 0 %. 1H NMR analysis revealed that the biodegradation level can be correlated with the presence of specific polymers. These findings highlight concerns about the environmental impact of combined materials when one fraction, here the liner, that fails to biodegrade, even if the trays themselves pass biodegradation tests. The study underlines the importance of assessing the biodegradation of the final packaging as a whole, rather than evaluating only the raw materials
Évaluer l'écotoxicité terrestre des mélanges de contaminants apportés par les produits organiques en analyse du cycle de vie (Pro en ACV)
No full textSource Agritrop Cirad (https://agritrop.cirad.fr/616017/)National audienceUSEtox est le modèle de référence en analyse du cycle de vie (ACV) pour évaluer les impacts toxicologiques et écotoxicologiques des contaminants émis dans l'environnement. Appliqué à l'évaluation environnementale de scénarios de valorisation agricole de produits organiques, plusieurs études basées sur USEtox ont suggéré que les impacts en termes de toxicité humaine et d'écotoxicité aquatique étaient très majoritairement dominés par les éléments traces, avec un impact négligeable des contaminants traces organiques (hors pesticides). Ce constat reste pourtant questionnable du fait d'une absence de prise en compte de la biodisponibilité des contaminants chimiques au niveau du sol, alors même qu'il constitue le premier réceptacle de ces contaminants dans l'environnement lors de l'épandage de produits organiques. Cette déficience de USEtox se traduit d'ailleurs par l'absence actuelle de méthode permettant d'évaluer l'impact des contaminants chimiques en termes d'écotoxicité terrestre. Les travaux menés dans le cadre du projet ACV-Ecoto(Mi)x (2022-2025, Ademe) ont donc eu pour objectif de proposer une méthode basée sur USEtox permettant l'évaluation en ACV de l'impact sur les organismes du sol des mélanges de contaminants apportés lors de la valorisation agricole des produits organiques. Concernant les éléments traces, la méthode initialement proposée dans la littérature pour prendre en compte leur biodisponibilité a été révisée afin d'intégrer l'évolution des propriétés physico-chimiques du sol suite à l'apport de produits organiques. Pour les contaminants traces organiques, une analyse de la littérature complétée par des expérimentations de sorption au laboratoire et le recours à l'outil de classification TyPol ont permis de proposer des équations pour estimer le coefficient de partage solide- solution de plusieurs dizaines de molécules en fonction des propriétés physico- chimiques du sol. Cela a permis de calculer l'impact de ces contaminants en termes d'écotoxicité terrestre. L'établissement au laboratoire de courbes de réponse d'organismes modèles du sol à deux éléments traces (cuivre et zinc) et deux contaminants traces organiques (diclofenac et ofloxacine) a permis d'évaluer les effets de mélange (synergique ou antagoniste) de contaminants. Ces résultats ont enfin été appliqués à l'évaluation de l'impact écotoxicologique sur les organismes du sol de scénarios agronomiquement réalistes d'apport de 12 produits organiques (d'origine agricole, urbaine ou agro-industrielle, transformés ou non) sur 5 sols (dont 4 issus des essais du réseau Soere Pro). Ce travail a permis de hiérarchiser les contaminants et les produits organiques les plus préoccupants en termes d'écotoxicité terrestre, ainsi que les propriétés de sol susceptibles d'influencer cet impact
Towards a new standard: Procedure proposal for the determination of mist explosion characteristics
No full textInternational audienceDespite the occurrence of numerous accidental mist explosions, standards for the determination of liquid aerosols explosivity are still not available. This is mainly due to the lack of means of characterization, available data, and scientific knowledge in such a matter. This article proposes a complete procedure allowing the evaluation of the ignition sensitivity and explosion severity of fuel mist clouds. Specific test procedures were recommended based on a classification system dividing liquids into four quadrants according to their flash point and droplet stability during secondary atomization (i.e. the Weber ratio). The dedicated test equipment is based on a 20L explosion sphere modified to generate a hydrocarbon mist with controlled characteristics (diameter, concentration, etc.). The proposed procedures were successfully applied to seven fuels (e.g. kerosene and lube oil) and could then serve as the basis for a new standard. This article also put forward the application of such procedures in industrial cases to illustrate the importance of considering scenarios involving the generation of fuel mists, particularly those with high flashpoints, and the need to assess the safety parameters of mists through experimental means for standardization. Suitable prevention, protection and mitigation measures can then be implemented in a harmonized and systematic way
Optimizing computation time in 3D air quality models by using aerosol superbins within a sectional size distribution approach: Application to the CHIMERE model
No full textInternational audienceOne limitation of the operational application of air-quality models at high resolution for forecasting or for the evaluation of emission mitigation scenario is the computational cost. It may also be an important limitation to the use of more complex (but more realistic) secondary organic aerosol (SOA) schemes. While the size distribution may be accurately described with a sectional approach to resolve processes involved in aerosol dynamics, it also leads to large CPU time due to the number of size bins that need to be used.In this study, we developed a “superbin” approach consisting in lumping for a given species several size bins into a single size superbin and to use a specified size distribution to distribute the superbin concentration into the different bins of CHIMERE when needed.Together with the revision of the numerical resolution algorithm, the ”superbin” approach was implemented into a new version of CHIMERE (based on v2020r1) in order to optimize the CPU time performance. The computation time was reduced by 60% with induced errors on PM10 concentrations around 3% to 7% over most of Europe. The use of the “superbin” approach proved to be much more efficient in terms of computational time and errors compared to simply reducing the number of bins
Characterization of brown carbon absorption in different European environments through source contribution analysis
No full textInternational audienceBrown carbon (BrC) is a fraction of organic aerosol (OA) that absorbs radiation in the ultraviolet and short visible wavelengths. Its contribution to radiative forcing is uncertain due to limited knowledge of its imaginary refractive index (k). This study investigates the variability of k for OA from wildfires, residential, shipping, and traffic emission sources over Europe. The Multiscale Online Nonhydrostatic Atmosphere Chemistry (MONARCH) model simulated OA concentrations and source contributions, feeding an offline optical tool to constrain k values at 370 nm. The model was evaluated against OA mass concentrations from aerosol chemical speciation monitors (ACSMs) and filter sample measurements, as well as aerosol light absorption measurements at 370 nm derived from an Aethalometer™ from 12 sites across Europe. Results show that MONARCH captures the OA temporal variability across environments (regional, suburban, and urban background). Residential emissions are a major OA source in colder months, while secondary organic aerosol (SOA) dominates in warmer periods. Traffic is a minor primary OA contributor. Biomass and coal combustion significantly influence OA absorption, with shipping emissions also notable near harbors. Optimizing k values at 370 nm revealed significant variability in OA light absorption, influenced by emission sources and environmental conditions. Derived k values for biomass burning (0.03 to 0.13), residential (0.008 to 0.13), shipping (0.005 to 0.08), and traffic (0.005 to 0.07) sources improved model representation of OA absorption compared to a constant k. Introducing such emission source-specific constraints is an innovative approach to enhance OA absorption in atmospheric models
User guide for ACSM data processing and PMF application using SoFi Pro
No full textThis document is intended for everyone who wants to investigate source apportionment using the PMF method on SoFi Pro software. This version is specifically designed for the analysis of ACSM data. It details all the steps for the preparation of data in Igor within the ACSM data acquisition software (ACSM Local, Aerodyne Research Inc.) and then the steps to perform PMF using SoFi (Source Finder Datalystica Ltd., Villigen, Switzerland)