1. Αποθετήριο Παραδοτέων Υποτρόφων Δράσεων ΕΣΠΑ Τριτοβάθμιας Εκπαίδευσης 2017-2023
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3. Υποψήφιοι διδάκτορες

Τύπος:	Διδακτορική διατριβή
Τίτλος:	Methods and techniques for the assessment of vehicular exhaust particulate emissions using alternative fuels and advanced emission control systems
Εναλλακτικός τίτλος:	Μέθοδοι και τεχνικές για την αξιολόγηση σωματιδιακών εκπομπών οχημάτων με χρήση εναλλακτικών καυσίμων και εξελιγμένων συστημάτων αντιρρύπανσης
Συγγραφέας:	[EL] Κόντσες, Αναστάσιος[EN] Kontses, Anastasios
Επιβλέπων διατριβής:	[EL] Ντζιαχρήστος, Λεωνίδας[EN] Ntziachristos, Leonidas
Συμβουλευτική επιτροπή:	[EL] Σαμαράς, Ζήσης[EN] Samaras, Zissis [EL] Σιούτας, Κωνσταντίνος[EN] Sioutas, Constantinos
Μέλος εξεταστικής επιτροπής:	[EL] Κολτσάκης, Γρηγόριος[EN] Koltsakis, Grigorios [EN] Hausberger, Stefan [EL] Καραβαλάκης, Γεώργιος[EN] Karavalakis, Georgios [EN] Giechaskiel, Barouch
Ημερομηνία:	Ιου-2019
Περίληψη:	Executive Summary Particulate matter is a major concern for air quality nowadays, being associated with increased mortality and morbidity, with relevant diseases including stroke, heart failure, lung cancer and respiratory disorders (WHO, 2016). It also degrades the environment, mainly due to haze formation and alteration of ecosystem diversity (EPA, 2018). Among the main anthropogenic particulate matter sources, road transport sector has been a major contributor over the last decades (EEA, 2018). The introduction of strict regulation limits has brought significant particulate emissions reductions, but road vehicles are still responsible for 11% of fine particulate mass (PM2.5) (EEA, 2018) and up to 90% of particle number emissions in highly trafficked urban roads (Kumar et al., 2014). Since the early ’90s, the European regulatory framework on vehicular exhaust particulate emissions has focused on diesel vehicles, and this has been also extended to gasoline direct injection (GDI) engines since 2009. This has been based on a solid body of evidence showing that these two powertrain types can produce significant particulate emissions when no PM-specific aftertreatment is used. With specific emissions control introduced for these technologies, it has to be investigated if other fuel and powertrain technologies now emerge as candidates for regulatory control. The current study investigates this dimension, focusing on light-duty and L-category (i.e. 2-, 3- and light 4-wheeler) vehicles. With regard to L-category vehicle family, the current (Euro 4) regulatory framework prescribes a lenient PM limit (80 mg/km) for diesel vehicles (not in all sub-categories), while a more stringent limit (4.5 mg/km) will be applied for all diesel and GDI L-category vehicles in Euro 5 step, from 2020 onwards. The objective of the current study was to evaluate particulate emissions from a wide range of L-category vehicles, covering different sub-categories (i.e. mopeds, motorcycles, quads and minicars) and engine types (i.e. two-stroke (2S) and four-Stroke (4S) gasoline and 4S diesel), and to assess if these need to be specifically addressed under the upcoming Euro 5 regulation, further to diesel and GDI. Tests were performed on a chassis dynamometer with 30 L-category vehicles, covering all relevant sub-categories and engine technologies. The design of these tests was performed in collaboration with the JRC colleagues, while I was also actively involved in the measurement campaign, which was performed at JRC. Results showed that 2S mopeds and diesel minicars comprised the highest PM and solid particle number (above 23 nm, SPN23) emitters (up to 64 mg/km and 450×1011 p/km, respectively), reaching emission levels of older-technology diesel cars without diesel particulate filter (DPF). SPN23 emissions from diesel minicars were found on average equivalent to 200 DPF-equipped passenger cars. The Euro 5 PM limit (4.5 mg/km) will be applicable to L-category minicars with a 2-year extra lead time, in 2022; hence, significant emissions reductions are expected from this sub-category. However, it is uncertain whether diesel minicars at Euro 5 can afford a DPF. Two-stroke mopeds with current emission abatement technologies are not expected in large numbers at Euro 5 due to their inability to comply with the future stringent hydrocarbon (HC) limit that will require costly engine and aftertreatment emission control measures. Emissions of 4S mopeds, motorcycles, and quads, were found to be one order of magnitude lower than 2S and, already below the Euro 5 limit. On the other hand, SPN23 emissions from these sub-categories were up to 5 times higher than the Euro 6 passenger car limit (6×1011 p/km). Even latest Euro 4 motorcycles exceeded that limit by up to 3 times. Moreover, the current study showed that when SPN in the range 10-23 nm is considered, SPN emissions above 10 nm (SPN10) are 2.4 times higher than SPN23, while the number of volatile and semi-volatile particles is also significant. Finally, cold engine operation was shown to increase SPN23 by up to 17 times over hot operation, especially in the case of low emitters. These results indicate that emissions from several sub-categories of L-vehicles of current technology are above PM and SPN23 limits. Future legislation may have to consider these vehicle types as well, such as for example the extension of the PM limit to 2S mopeds. Consideration to also develop a specific SPN limit, in analogy to passenger cars, may be also required if the PM limit alone is not shown to considerably decrease the number of particles. In such a case, one will have to address sampling implications of the high semi-volatile material content in the exhaust of L-category vehicles. In the case of passenger cars, a PM limit of 4.5 mg/km and a SPN23 limit of 6×1011 p/km are currently applied to Euro 6 vehicles equipped with diesel or GDI engines. The objective of the current study for light-duty vehicles was to evaluate particulate emissions from different fuel and powertrain technologies (diesel, gasoline, LPG, CNG and electro-hybrid vehicles) in order to determine the real-world environmental effect of each one. Based on these results it can be determined if engine and fuel types other than diesel and GDI, should be addressed by particulate emissions regulations. The method followed comprised measurements under real-world driving conditions on-road, over two different test routes (“RDE-compliant” and “RDE-dynamic”) covering a wide range of driving conditions (high and frequent acceleration and deceleration events) and road characteristics (steep road gradient with high positive elevation gain). This measurement campaign was designed and performed (I was actively involved in the on-road tests) in the framework of the scholarship I received from the State Scholarships Foundation. The highest SPN23 emissions (over cold-start RDE-compliant route) were observed in a Euro 6b gasoline vehicle equipped with PFI engine, while similar emission levels were detected in the older-technology (Euro 3 and 4) gasoline and (retrofitted) LPG PFI vehicles (up to 4.5 times higher than the Euro 6 limit of 6×1011 p/km). An interesting finding was that SPN23 emissions from the Euro 6b hybrid-electric (with PFI engine) vehicle also exceeded (by 10%) the Euro 6 limit. High variation was observed in Euro 6b GDI vehicles (without particulate filter), with one vehicle being above (1.7 times) and the other below (4 times) the Euro 6 limit. The lowest emissions were detected in DPF-diesel and CNG (without particulate filter) vehicles (up to 77 and 25 times lower than the Euro 6 limit respectively). Euro 6b LPG vehicle appeared also to be a low emitter (3.3 times lower than the Euro 6 limit). LPG and CNG were found to significantly reduce SPN23 emissions compared to gasoline (up to 93% and 90% respectively), although the opposite trend was observed in an old-technology retrofitted LPG vehicle. In almost all cases, dynamic driving conditions and high elevation gain (i.e. over RDE-dynamic route) resulted in a significant increase of SPN23 emissions. Finally, among the different driving sections (urban, rural, motorway) of the cold-start RDE-compliant route, urban and especially the cold phase had the highest contribution in most cases. These results indicate that close attention should be focused on other engine and fuel types, further to diesel and GDI. Regulatory initiatives towards air pollution reduction shall include measures for the reduction of old-technology gasoline and LPG vehicles fleet, while attention is also needed in modern gasoline PFI engines. As a last step, the potential to further reduce particulate emissions of diesel vehicles through fuel refinement was investigated, with a focus on latest-technology DPF-equipped vehicles. More specifically, the effect of fuel density, cetane number (CN), polycyclic aromatic hydrocarbons (PAH) and Fatty Acid Methyl Ester (FAME, 1st generation biodiesel) content on particulate emissions, size distribution and chemical composition (ions, soluble organic fraction – SOF and elemental carbon) was evaluated. Tests were conducted on a chassis dynamometer (in which I was also actively involved in) with two DPF-equipped (Euro 5 and 6) and one non-DPF (Euro 4) vehicle fueled by 13 different test fuels and one reference (as a market fuel representative). Statistically significant differences in PM and SPN23 emissions were observed among the studied vehicles, even between the DPF-equipped ones. PM and SPN23 emissions of the Euro 5 car were up to 3 and 14 times higher than the Euro 6 one respectively. Fuel type was found to significantly affect PM and SPN23 emissions. Differences of up to ±50% from reference fuel were observed in PM, while SPN23 emissions were found to be 3-6 times higher than reference fuel in some cases of Euro 5 car. From a statistical point of view, fuel properties significantly affected particulate emissions and size distribution in almost all cases of Euro 4 car, while some statistically significant trends were also observed in Euro 5 and 6 vehicles. More specifically, high fuel density was found to decrease SPN23 emissions under Cold NEDC, while FAME resulted in a SPN23 increase (only in Euro 6) over the same cycle. These effects can be attributed to the impact of density and FAME on engine-out emissions and the respective acceleration and deceleration of DPF soot loading after regeneration. Finally, particulate matter chemical composition was found to be insensitive to fuel properties variations in all vehicles. These results indicate that the use of DPF has, to a large extent, masked the role of fuel properties on particulate emissions, but there is still some room for optimisation, especially in SPN23 emissions after DPF regeneration. Thus, a revision of regulation limits on fuel properties should be further investigated. However, the secondary impact of fuel properties on DPF regeneration frequency should also be carefully assessed. Η παρούσα διδακτορική διατριβή εστιάζει στην αξιολόγηση των σωματιδιακών εκπομπών οχημάτων, καλύπτοντας ένα ευρύ φάσμα διαφορετικών τύπων οχημάτων (επιβατικά και οχήματα της κατηγορίας «L», δηλαδή δίτροχα, τρίτροχα και ελαφρά τετράτροχα), καυσίμων (πετρέλαιο, βενζίνη, υγραέριο, φυσικό αέριο και ηλεκτρο-υβριδικά οχήματα), τεχνολογιών κινητήρα και συστημάτων αντιρρύπανσης. Η μελέτη βασίζεται σε μετρήσεις ρύπων σε εργαστηριακό περιβάλλον (πέδη οχημάτων) και σε πραγματικές συνθήκες στο δρόμο. Ο κύριος στόχος της διατριβής ήταν να προσδιοριστούν οι τεχνολογίες κινητήρα και τα είδη καυσίμου, στα οποία θα πρέπει να επεκταθεί η υπάρχουσα νομοθεσία, η οποία επικεντρώνεται προς το παρόν μόνο στις σωματιδιακές εκπομπές από πετρελαιοκίνητα οχήματα και από οχήματα με κινητήρα άμεσης έγχυσης καυσίμου. Επιπλέον, αξιολογήθηκε το περιθώριο περαιτέρω μείωσης των σωματιδιακών εκπομπών των σύγχρονων πετρελαιοκίνητων οχημάτων μέσω της αλλαγής των ιδιοτήτων του καυσίμου. Εστιάζοντας αρχικά στα οχήματα της κατηγορίας «L» (η υπάρχουσα και η προσεχής νομοθεσία προβλέπουν όριο εκπομπών μόνο για την μάζα των σωματιδίων), τα αποτελέσματα της έρευνας φανέρωσαν ότι εκτός από τα πετρελαιοκίνητα οχήματα, υψηλές σωματιδιακές εκπομπές (μάζας και αριθμού σωματιδίων) παρατηρούνται και σε άλλες τεχνολογίες κινητήρα. Πιο συγκεκριμένα, οχήματα εφοδιασμένα με δίχρονους βενζινοκινητήρες παρουσίασαν υψηλές εκπομπές μάζας και αριθμού σωματιδίων, κοντά στα επίπεδα των πετρελαιοκίνητων οχημάτων (χωρίς φίλτρο κατακράτησης σωματιδίων), ενώ υψηλές εκπομπές αριθμού σωματιδίων παρατηρήθηκαν και στις υπόλοιπες υποκατηγορίες που μελετήθηκαν, παρόλο που η εκπεμπόμενη μάζα σωματιδίων ήταν σε επίπεδα κάτω από τα νομοθετημένα όρια. Όσον αφορά τα επιβατικά οχήματα, οι υψηλότερες εκπομπές αριθμού σωματιδίων (υπό πραγματικές συνθήκες οδήγησης) παρατηρήθηκαν στα οχήματα βενζίνης (έμμεσης έγχυσης καυσίμου) και υγραερίου, ιδιαίτερα στα παλαιότερης τεχνολογίας, ξεπερνώντας κατά πολύ το όριο της νομοθεσίας (παρόλο που αυτό δεν ισχύει για αυτές τις τεχνολογίες κινητήρα). Πολύ χαμηλές ήταν οι εκπομπές των πετρελαιοκίνητων οχημάτων (χάρη στην τοποθέτηση φίλτρου σωματιδίων) και του οχήματος φυσικού αερίου που μελετήθηκε. Αξιοσημείωτο είναι το γεγονός ότι οι εκπομπές του ηλεκτρο-υβριδικού οχήματος ήταν σχετικά υψηλές συγκριτικά με συμβατικά οχήματα με κινητήρα έμμεσης έγχυσης καυσίμου, ξεπερνώντας μάλιστα το όριο της νομοθεσίας (το οποίο δεν ισχύει ούτε σε αυτή την τεχνολογία κινητήρα). Όσον αφορά την μελέτη των ιδιοτήτων του καυσίμου, προέκυψε ότι αυτές μπορούν να επηρεάσουν σημαντικά τις σωματιδιακές εκπομπές ακόμα και των σύγχρονων πετρελαιοκίνητων οχημάτων που είναι εφοδιασμένα με φίλτρο κατακράτησης σωματιδίων. Το συμπέρασμα που προκύπτει, λοιπόν, από την παρούσα διδακτορική έρευνα είναι ότι τόσο στα οχήματα της κατηγορίας «L», όσο και στα επιβατικά οχήματα, το ενδιαφέρον της νομοθεσίας θα πρέπει να στραφεί και προς άλλες τεχνολογίες, οι οποίες παρουσίασαν υψηλές σωματιδιακές εκπομπές. Στην περίπτωση των οχημάτων της κατηγορίας «L» το όριο εκπομπών μάζας σωματιδίων θα πρέπει να επεκταθεί και στους δίχρονους κινητήρες, ενώ για τις υπόλοιπες υποκατηγορίες η υιοθέτηση ενός ορίου για τις εκπομπές αριθμού σωματιδίων ίσως είναι απαραίτητη. Στα επιβατικά οχήματα, προσοχή θα πρέπει να δοθεί στα παλαιότερης τεχνολογίας οχήματα βενζίνης και υγραερίου, ενώ στο μικροσκόπιο θα πρέπει επίσης να βρεθούν τα βενζινοκίνητα (έμμεσης έγχυσης καυσίμου) και τα ηλεκτρο-υβριδικά οχήματα τελευταίας τεχνολογίας. Τέλος, όσον αφορά την βελτίωση των ιδιοτήτων του καυσίμου, προτείνεται η αναθεώρηση των ορίων της νομοθεσίας ώστε να ληφθεί υπόψη και η επίδρασή τους στις σωματιδιακές εκπομπές των οχημάτων τελευταίας τεχνολογίας.
Γλώσσα:	Αγγλικά
Τόπος δημοσίευσης:	Thessaloniki, Greece
Σελίδες:	146
Θεματική κατηγορία:	[EL] Μηχανολογία[EN] Mechanics
Λέξεις-κλειδιά:	Σωματιδιακές εκπομπές οχημάτων; Εναλλακτικά καύσιμα; Πραγματικές συνθήκες οδήγησης; Νομοθεσία εκπομπών ρύπων οχημάτων
Κάτοχος πνευματικών δικαιωμάτων:	© Anastasios Kontses
Διατίθεται ανοιχτά στην τοποθεσία:	https://www.didaktorika.gr/eadd/handle/10442/45960
Σημειώσεις:	“This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Scholarships programme for post-graduate studies - 2 nd Study Cycle” (MIS-5003404), implemented by the State Scholarships Foundation (ΙΚΥ).”
Εμφανίζεται στις συλλογές:	Υποψήφιοι διδάκτορες