Modeling of Methane Slip in Two-Stroke Dual-Fuel Marine Engines

Κωστούλας, Βασίλειος; Kostoulas, Vasileios

dc.contributor.author	Κωστούλας, Βασίλειος	el
dc.contributor.author	Kostoulas, Vasileios	en
dc.date.accessioned	2023-04-06T07:20:14Z
dc.date.available	2023-04-06T07:20:14Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/57488
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.25185
dc.rights	Αναφορά Δημιουργού 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by/3.0/gr/	*
dc.subject	Methane Slip	en
dc.subject	Decarbonization	en
dc.subject	Thermodynamic Modeling	en
dc.subject	Dual-Fuel Engines	en
dc.subject	Alternative Fuels	en
dc.subject	Ναυτικοί Κινητήρες	el
dc.subject	Ρύποι	el
dc.subject	Μεθάνιο	el
dc.title	Modeling of Methane Slip in Two-Stroke Dual-Fuel Marine Engines	en
dc.contributor.department	Division of Marine Engineering	el
heal.type	bachelorThesis
heal.classification	Marine Engineering	en
heal.language	en
heal.access	campus
heal.recordProvider	ntua	el
heal.publicationDate	2023-03-06
heal.abstract	Decarbonization is currently a central focus of the maritime sector, with the necessary actions regulated by the International Maritime Organization (IMO). On the road to decarbonization, Natural Gas (NG), consisting mainly of methane, is an intermediate fuel contributing the the reduction of greenhouse gas (GHG) emissions, until carbon-neutral fuel technology is developed and tested. Nonetheless, methane, whose presence in the exhaust emissions cannot be fully eliminated ("methane slip"), has a global warming potential (GWP) of about 30, i.e., it is more harmful, in terms of the greenhouse effect, than carbon dioxide (CO2), by a factor of 30. Dual-fuel marine engines, which can operate both in the diesel and in the gas mode, are acquiring an increasing share of marine propulsion. Among them, engines using the low pressure gas admission principle are characterized by important advantages, such as the substantial decrease of nitrogen oxides (NOx) and particulate matter (PM) emissions. The main goal of the present thesis is to develop and test a model for predicting methane emissions from low-pressure dual-fuel engines, and test it for the case of large two-stroke marine engines. In particular, a phenomenological model for predicting methane slip is developed in the frame of the GT-Suite 0D/1D-CFD simulation tool, and is coupled with a double Wiebe function combustion model. The present methane slip model accounts for: (i) near-wall flame quenching, and (ii) trapping of unburned mixture in the crevices volume. Here, quenching of the premixed flame utilizes Peclet number considerations, while modeling of unburned mixture flow into/from crevices is based on an adaptation of the equation of state. To calibrate the model, experimental pressure data has been used from a large two-stroke dual-fuel test engine of Winterthur Gas & Diesel (WinGD). The cases considered correspond to operation at about 75% of the maximum load, and different experimental engine tunings. For those cases, computational results for methane exhaust concentration were in qualitatively good agreement with experiments. Deviations between experimental and model results could possibly be attributed to the fact that the present modeling does not account for the direct slip during scavenging. The present computational results demonstrate that near-wall flame quenching and the crevices volume have a nearly equal contribution to methane slip for all the experimental cases considered here. Overall, the present work is an important first step for accurate prediction of methane slip in low-pressure dual-fuel marine engines by means of thermodynamic modeling.	en
heal.advisorName	Καϊκτσής, Λάμπρος	el
heal.advisorName	Kaiktsis, Lambros	en
heal.committeeMemberName	Belibassakis, Konstantinos	en
heal.committeeMemberName	Papadopoulos, Christos	en
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Μηχανολόγων Μηχανικών	el
heal.academicPublisherID	ntua
heal.numberOfPages	70 p.	en
heal.fullTextAvailability	false