Contribution to the understanding of filtration and pressure drop phenomena in wall-flow DPFs

From the last decades of the 20th century, internal combustion engines have undergone a continuous improvement process aimed to the increase of their efficiency and decrease of the pollutants emissions. The reduction of the availability of fossil fuel and the increase of human-made pollution observed in the last decades is leading worldwide to more stringent emission standards that make the engine manufacturers to constantly look for fuel consumption and emission reductions while keeping engine performance. To comply with current and incoming emission regulations, the exhaust line of internal combustion engines has been gradually complicated by the presence of aftertreatment systems. Among them, the particulate filter is the device in charge of abating the emission of soot in the atmosphere. Concerning compression ignition engines, diesel particulate filters (DPF) were first commercially utilized in significant numbers in passenger car and heavy-duty engines since the beginning of the 21st century. Euro 6 emission standards limits the emitted particulate matter from direct injection engines, thus extending the use of particulate filters also to direct injection gasoline engines. A deep knowledge of the phenomena happening inside the DPF is required for the correct understanding of the behaviour of this system and its interaction with the engine. The precise knowledge of the filtration and pressure drop processes is mandatory for the design of the particulate filter and is also essential to wisely think up and analyse solutions aimed to limit the negative impact of the filter on the fuel consumption maintaining its capability of retaining soot particles. Thus, the present work pretends to provide a contribution to the understanding of these phenomena in wall-flow DPFs. The problem has been faced on a computational and experimental basis. A notable part of the work was dedicated to the development and validation of a one-dimensional DPF filtration model to be coupled with the existing pressure drop model. The model was implemented in OpenWAM¿, the open-source gas dynamics software for internal combustion engines and components computation developed at CMT - Motores Térmicos. The developed computational tool was applied to the assessment of the aftertreatment (DOC&DPF) volume downsizing potential in post- and pre-turbo aftertreatment configuration. The study is completed with experimental analysis to support theoretical insights discussing how the soot deposition profile and the particulate layer properties impact on the DPF pressure drop.Desde las últimas décadas del siglo XX, se ha producido un proceso de mejora continua de los motores de combustión interna alternativos con el fin de aumentar su eficiencia y reducir las emisiones contaminantes. La reducción de la disponibilidad de combustibles fósiles y el incremento de la polución de origen antropogénico observados en las ultimas décadas ha provocado el progresivo endurecimiento de las normativas anticontaminación a nivel mundial obligando a los fabricantes de motores a buscar la reducción continua del consumo de combustible y emisiones, manteniendo las prestaciones del motor. El cumplimiento de las actuales y futuras normativas anticontaminación requiere de la instalación de diversos sistemas de postratamiento de gases en la línea de escape de los motores de combustión interna alternativos, aumentando su complejidad. Entre estos sistemas, el filtro de partículas es el equipo encargado de la reducción de la emisión de hollín a la atmósfera. Con respeto a los motores de encendido por compresión, los filtros de partículas diésel se implementaron por primera vez de forma masiva en vehículos de pasajeros y vehículos pesados a principio del siglo XXI. La normativa anti contaminación Euro 6 limita las emisiones de partículas de los motores de inyección directa, extendiendo el uso de filtros de partículas a los motores de inyección directa de gasolina. Es necesario tener un conocimiento profundo de los fenómenos que tienen lugar en el DPF para comprender el comportamiento de este sistema y su interacción con el motor. El conocimiento de los procesos de filtrado y perdida de presión es vital para el diseño del filtro de partículas y resulta esencial para encontrar y analizar soluciones que ayuden a limitar el impacto negativo del DPF sobre el consumo de combustible sin perder la capacidad de retener partículas de hollín. En este contexto, este trabajo pretende aportar una contribucción a la comprensión de estos fenómenos en filtros de partículas de flujo de pared. Esta tarea se ha planteado desde un punto de vista computacional y experimental. Parte importante de este trabajo ha consistido en el desarrollo y validación de un modelo de filtrado unidimensional de DPF que se ha acoplado con el modelo de caida de presión ya existente. El modelo se ha implementado en OpenWAM¿, el software de libre acceso para el cálculo fluidodinámico de motores de combustión interna y sus componentes desarrollado en CMT - Motores Térmicos. La herramienta computacional desarrollada se ha aplicado a la evaluación del potencial de reducción de volumen de sistemas de postratamiento (DOC&DPF) en configuraciones post- y pre-turbo. Este estudio se ha completado con un análisis experimental para dar respaldo a los conceptos teóricos empleados discutiendo como el perfil de deposición del hollín y las propiedades de la capa de partículas afectan a la perdida de presión del DPF.Des les últimes dècades del segle XX, s'ha produït un procés de millora contínua dels motors de combustió interna alternatius amb l'objectiu d'augmentar la seua eficiència i reduir les emissions contaminants. La reducció de la disponibilitat de combustibles fòssils i l'increment de la polució d'origen antropòlogic observats en les últimes dècades ha provocat que les normatives anticontaminació s'han fet més rígides a nivell mundial, obligant als fabricants de motors a buscar la reducció contínua del consum de combustibles i emissions, mantenint les prestacions dels motors. El cumpliment de les normes anticontaminació actuals i futures, requereixen de l'instalació de diversos sistemes de post-tractament de gasos a l'eixida dels motors de combustió interna alternatius, llavors augmentant la complexitat. Entre aquestos sistemes, el filtre de partícules es l'equip encarregat de la reducció de les partícules de sutge a l'atmosfera. Respecte als motors d'encès per compressió, els filtres de partícules van instalar-se de manera massiva als vehicles de passatgers i vehicles pesats al principi del segle XXI. La normativa anti contaminació Euro 6 limita les emissions de partícules dels motors d'inyecció directa, estenent l'ús del filtre de partícules als motors d'injecció directa de gasolina. És necessari tindre un coneixement dels fenòmens que tenen lloc al DPF per a comprendre el comportament del sistema i la seua interacció amb el motor. El coneixement dels processos de filtrat i la pèrdua de pressió és vital per al diseny del filtre de partícules i resulta essencial per a trobar i analitzar les solucions que ajuden a limitar l'impacte negatiu del DPF sobre el consum de combustible sense perdre la capacitat de retenir partícules de sutge. En aquest context, el projecte pretén aportar una contribució a la comprensió d'aquestos fenòmens en els filtres de partícules de flux de paret. Aquesta feina s'ha plantejat des d'un punt de vista computacional i experimental. Part important d'aquest treball ha consistit en el desenvolupament i validació d'un model de filtrat unidimensional de DPF que s'ha acoplat a un model de pèrdua de pressió existent. El model s'ha implementat en OpenWAM¿, el software de lliure accés per al cálcul fluidodinámic de motors de combustió interna i els seus components desenvolupats al CMT - Motores Térmicos. La ferramenta computacional desenvolupada s'ha aplicat a la evaluació del potencial de reducció del volum de sistemes de post tractament (DOC&DPF) en les configuracions post- i pre-turbo. Aquest estudi s'ha completat amb una anàlisi experimental per a donar suport als concepts teòrics emprats discutint com el perfil de la disposició de sutge i les propietats de la capa de partícules que afecten a la pèrdua de pressió del DPF.Angiolini, E. (2017). Contribution to the understanding of filtration and pressure drop phenomena in wall-flow DPFs [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/86157TESI

The plant communities of Tuscan rice fields

Vascular plants colonizing rice fields are highly specialized to grow in such a peculiar habitat, which is at a crossroad between wetlands and arable land. Italy is one of the main rice producers in the World, and most of its rice production is concentrated in northern regions. A few descriptive studies are available about the plant communities colonizing rice fields in the area. On the contrary, nothing is known about such communities in central Italy (Tuscany), where rice cultivation has a long tradition as well. With this study, we provide the first knowledge about the plant communities growing in the rice fields of southern Tuscany, where we carried out 40 square vegetation plots of 4 m2 size in early September 2021 and 2022. The surveyed plant communities were characterized by a high presence of alien species, such as Cyperus difformis, Heteranthera reniformis, and Lindernia dubia, and were classifiable in the class Oryzetea sativae Miyawaki 1960. However, based on preliminary floristic observations and on distributional data from literature, most of such alien species seemed unable to spread outside rice fields and their immediate channels, except for the invasive plant of European concern Hydrocotyle ranunculoides. Among native species, the most frequent were Alisma plantago-aquatica, Bolboschoenus maritimus, and Cyperus fuscus. An abundant presence of Characeae algae was often recorded. The channels surrounding rice fields host natural aquatic communities with Potamogeton spp., Utricularia spp., and Najas spp., classifiable in the class Potamogetonetea Klika in Klika et Novák 1941 and representing the Natura 2000 Habitat 3260 “Water courses of plain to montane levels with the Ranunculion fluitantis and Callitricho-Batrachion vegetation”

Dose-Dependent and Species-Specific Effects of Wood Distillate Addition on the Germination Performance of Threatened Arable Plants

Wood distillate (WD) is a bio-based product applied to crop plants for its known action in terms of growth promotion and yield enhancement, but studies are lacking on its effects on the germination of arable plants. To test such effects, we applied WD at six different concentrations on the diaspores of three threatened arable plants: Bromus secalinus, Centaurea cyanus, and Legousia speculum-veneris. For all the studied species, the effect of WD was dose-dependent and species-specific. In B. secalinus, the germination percentage (GP) decreased at 0.125% WD but then remained stable at higher concentrations up to 1%. At 2% WD, almost no germination was observed. Mean germination time (MGT) was not influenced up to 1% WD but significantly increased at 2% WD. The germination rate index (GRI) and germination energy (GE) remained unaffected up to 1% WD but decreased at 2% WD. In C. cyanus, WD had no effects on GP and GE at any concentration. MGT showed no difference with the control up to 1% WD, but significantly increased at 2% WD. GRI increased only at low concentrations (0.125% and 0.25%). The germination performance of L. speculum-veneris was unaffected up to 0.25% WD for all the tested parameters. From 0.5% WD, a reduction in GP, GRI, and GE and an increase in MGT were observed. At 2% WD, germination was totally blocked. Our results suggest that using WD at low concentrations (<0.5%), those commonly used in arable crops, does not affect the germination of the three investigated plant species

Summer roadside vegetation dominated by Sorghum halepense in peninsular Italy: survey and classification

Sorghum halepense is a synanthropic tall grass distributed worldwide from tropical to temperate zones, and it is often considered an invasive alien. It is a perennial, rhizomatous plant that tends to form dense stands derived from vegetative and sexual propagation. Despite roadside plant communities dominated by Sorghum halepense are very common in southern Europe, their phytosociological aspects are scarcely studied. In this work, we present the results of a vegetation survey in peninsular Italy, carried out by means of the phytosociological method. In total, we carried out 73 releves in Liguria, Tuscany, Latium, Campania, Basilicata, and Apulia. We statistically compared our releves to those from the Balkans classified in the Cynodonto-Sorghetum halepensis, an association of agricultural annual weed vegetation of the class Stellarietea mediae s.l. used in the past as a reference for Italian S. halepense-dominated communities. Our results show that the Italian communities are different from the Cynodonto-Sorghetum halepensis communities, since the latter are rich in annual species, while the former are rich in perennial species. From the syntaxonomic point of view, the Italian communities are better classified in the class Artemisietea vulgaris. We describe the new (sub-)ruderal association Potentillo reptantis-Sorghetum halepensis, including a meso-hygrophilous variant with Urtica dioica and an agricultural variant with Elymus repens. We have evidence that the Potentillo-Sorghetum occurs in Italy, Kosovo and Slovenia, but its distribution is possibly wider due to conspicuous presence of cosmopolitan species characterizing the association. Our work provides a baseline for the knowledge of an alien-dominated plant community that can invade habitats with high conservation value

Cupressus forests (Acero-Cupression; Habitat code 9290): A New EU Habitat in Italy?

In the European Union, the habitat type 9290 “Cupressus forests (Acero-Cupression)” is reported in more than 20 Natura 2000 sites of Greece and Cyprus. Scientific literature on the habitat 9290 is quite limited and the knowledge on its distribution needs more in-depth analyses and detailed studies. The Nature Reserve “Bosco di S. Agnese” (Siena, central Italy) hosts a large Cupressus sempervirens old-established forest (271 ha) originating from an ancient plantation (dated back to the Etruscan-ancient Roman times). Cupressus sempervirens seems to have found a precise ecological niche thus forming communities where the species is dominant. The aim of this study is to assess whether Cupressus sempervirens forest of Sant’Agnese can be considered as the first example of habitat 9290 in Italy. We compared it with the Cupressus sempervirens forests of the eastern Mediterranean area attributed to the habitat 9290. In June 2022, we collected original vegetation data in our study area. Moreover, additional data from the literature were retrieved for the eastern Mediterranean. A dataset of 217 vegetation relevés from Italy, Greece, Turkey, and Cyprus was obtained. Multivariate analyses (modified TWINSPAN and NMDS ordination) highlighted how the Cupressus sempervirens forest in S. Agnese has remarkable floristic affinities with the ones from Crete and other Aegean islands. Italian and Greek Cupressus sempervirens forests were distinguished in species composition from those in Turkey and Cyprus due to the presence of several species with a western Mediterranean distribution, such as Arbutus unedo, Pistacia lentiscus, and Quercus ilex, and to the absence (in Italy) or poorness (in Crete) of many eastern species, e.g., Acer sempervirens. These preliminary results, as well as the naturalness of the understorey and the potential distribution of habitat 9290 that includes the western Mediterranean basin, support the hypothesis that the EU habitat 9290 is also present in Sant’Agnese Nature Reserve and in Italy. Our study also showed that more extensive and in-depth studies on the typical species and on the distribution of the habitat 9290 in Europe are needed

Low Concentrations of Biochar Improve Germination and Seedling Development in the Threatened Arable Weed Centaurea cyanus

In the context of sustainable agriculture, the search for soil improvers that boost crop growth without harming biodiversity is gaining much attention. Biochar, the solid residue resulting from the pyrolysis of organic material, has recently emerged as a promising bioproduct in enhancing crop yield, but there is a lack of information regarding its effects on arable biodiversity. Thus, in this study, we tested the effect of biochar application on the germination and seedling growth of cornflower (Centaurea cyanus L., Asteraceae), a threatened arable weed, under laboratory conditions. We investigated various parameters, including germination percentage (GP%), mean germination time (MGT), germination rate index (GRI), germination energy (GE%), fresh and dry weight (mg) of seedlings, and radicle length (mm) under biochar treatments at different concentrations: 0% (control), 0.1%, 0.2%, 0.5%, 1%, and 2%. Our findings revealed a significant increase in GP, GE, and GRI at biochar concentrations of 0.5% and 1%. MGT slightly increased at 0.1% biochar. Seedling fresh weight was unaffected by biochar application, whereas seedling dry weight exhibited a significant increase at 0.5% biochar. Radicle length showed a substantial increase under 0.1% biochar on day one and was significantly higher at 0.2% and 1% biochar on day two. However, by day three, no more statistically significant differences in radicle length were observed between biochar-treated diaspores and controls (i.e., biochar had positive effects only in the first stages). These results suggest that the application of biochar at intermediate concentrations (0.5% and 1%) overall provide the most benefit to germination and seedling growth of C. cyanus

Differential effects of increasing temperature on the germination of five wild species with varying range sizes in a Carrara marble quarry

Assessing the performance of spontaneous plants in abandoned quarries under future environmental scenarios is important for successful restoration practices. Air warming is one of the most relevant ongoing climatic changes in the Mediterranean. We tested the effects of increasing temperature on the germination of five species spontaneously colonising the abandoned sectors of a Carrara marble quarry (Tuscany, central Italy). We selected five plant species with different widths of their distribution range, from local endemic to invasive alien: Santolina pinnata, Globularia incanescens, Hypericum coris, Helichrysum italicum, and Buddleja davidii. Seeds were collected in situ and their germination was tested in laboratory conditions at 10, 15, 20, 25, and 30°C. The effects of temperature and species on germination percentage (GP) and mean germination time (MGT) were tested through two-way ANOVA. Increasing temperatures negatively affected the GP of S. pinnata and H. coris. G. incanescens performed better at intermediate temperatures, while H. italicum benefited from increasing temperatures. B. davidii showed a similar high GP under all the treatments. MGT decreased with increasing temperature for all the species, except for S. pinnata, which showed an increase of MGT with increasing temperature. We highlighted that, under future warmer climatic conditions, the two endemic species will be disadvantaged with respect to the species with a wider distribution range and the non-native species in the studied quarry. This evidence is relevant for restoration planning since seeding the two endemic species could be unsuccessful under future environmental scenarios, when H. italicum and B. davidii will be more competitive in the colonisation of the quarry

Drivers of diversity of arable plant communities in one of their european conservation hotspots

The changes of agriculture led to deep transformations of arable plant diversity. The features of arable plant communities are determined by many anthropic, environmental, and geographic drivers. Understanding the relative importance of such drivers is essential for conservation and restoration purposes. In this work, we assessed the effects of agronomic, climatic, geographic, and landscape features on α-diversity, β-diversity, and composition of winter arable plant communities across continental Italy, a European hotspot of arable plant diversity. Using redundancy analysis and variation partitioning, we observe that the selected groups of variables explained a restrained to moderate proportion of the variation in diversity and composition, depending on the response (5.5–23.5%). We confirm previous evidence that climate and geographic location stand out in determining the features of arable plant communities in the country, followed by the type of rural area. The surrounding landscape has a subordinate influence but affects both α and β-diversity. The α-diversity is higher in traditional agricultural areas and in landscapes rich in woody vegetation, while it is lower in warmer areas. Species composition is determined by climate, latitude, and the type of rural area, but not by landscape. Total β-diversity is mainly explained by climate and latitude, and subordinately by the agricultural context and landscape. Its components are explained by latitude and climate (replacement) and agricultural context and climate (richness difference). The local contribution to β-diversity of single sites suggested a good conservation status of the studied communities. We discuss the implications of our findings in the light of conservation and restoration of vanishing arable plant communities

Effects of Wood Distillate on Seedling Emergence and First-Stage Growth in Five Threatened Arable Plants

Wood distillate (WD) is an environmentally safe bio-based product stimulating plant growth and yield and allowed in Italy in organic farming. To the best of our knowledge, there are no studies on the effects of WD on spontaneous plants growing among crops, including their functional traits such as biomass. To test such effects, we carried out a lab experiment on artificially reconstructed arable plant communities composed of five species of conservation interest, which are specialist winter cereal crops: Bromus secalinus L., Centaurea cyanus L., Lathyrus aphaca L., Legousia speculum-veneris (L.) Chaix, and Scandix pecten-veneris L. After sowing 45 pots under controlled conditions, we applied WD at three concentrations (0%, 0.2%, and 0.5%) six times over 7 weeks. The number of emerged plants in each pot was counted every two weeks. Finally, we harvested all plants and measured the fresh and dry above-ground weight of each species in each pot. The resulting data were analyzed by Permutational Analysis of Variance. The application of 0.2% and 0.5% WD modified the community composition after two weeks, but such differences later disappeared. Both 0.2% and 0.5% WD had a positive effect on the dry weight of S. pecten-veneris and a negative effect on that of L. speculum-veneris. Moreover, 0.2% and 0.5% WD increased seedling emergence in L. aphaca, and 0.5% WD increased seedling emergence in S. pecten-veneris. Both 0.2% and 0.5% WD enhanced seedling emergence in the entire community. We suggest that the use of WD at low concentrations in winter cereals may be a sustainable agricultural practice that benefits crops without harming the associated plant diversity

Robotic monitoring of forests: a dataset from the EU habitat 9210* in the Tuscan Apennines (central Italy)

Effective monitoring of habitats is crucial for their preservation. As the impact of anthropic activities on natural habitats increases, accurate and up-to-date information on the state of ecosystems has become imperative. This paper presents a new dataset collected from the forests located in the Tuscan Apennines (Italy) using the ANYmal robot. The dataset provides information regarding the structure and composition of the EU priority habitat 9210*. The dataset, which is publicly available through a Zenodo repository, includes photos, videos, and point clouds of the environment. This dataset is a valuable resource for the scientific community working in the field of forest ecology and conservation and has the potential to inform future research and conservation efforts on habitat 9210*. the collaboration between robotic engineers and plant scientists provides a unique perspective on the forest ecosystem and underscores the potential for interdisciplinary work in this field. This dataset constitutes an important contribution to the ongoing effort to monitor and conserve habitats globally, particularly in light of the challenges posed by global changes