Ανάπτυξη ημι-εμπειρικού μοντέλου καύσης για δίχρονο, ναυτικό κινητήρα διπλού καυσίμου, χαμηλής πίεσης

Κλάγκου, Μαργαρίτα; Klagkou, Margarita

dc.contributor.author	Κλάγκου, Μαργαρίτα	el
dc.contributor.author	Klagkou, Margarita	en
dc.date.accessioned	2020-05-18T13:13:59Z
dc.date.available	2020-05-18T13:13:59Z
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/50614
dc.identifier.uri	http://dx.doi.org/10.26240/heal.ntua.18312
dc.rights	Αναφορά Δημιουργού-Μη Εμπορική Χρήση-Όχι Παράγωγα Έργα 3.0 Ελλάδα	*
dc.rights.uri	http://creativecommons.org/licenses/by-nc-nd/3.0/gr/	*
dc.subject	Κινητήρας διπλού καυσίμου	el
dc.subject	Μοντέλο καύσης	el
dc.subject	Ημι-εμπειρικό μοντέλο	el
dc.subject	Φυσικό αέριο	el
dc.subject	Συνάρτηση "Βίμπε"	el
dc.subject	Dual fuel marine engine	en
dc.subject	Combustion model	en
dc.subject	Semi-empirical model	en
dc.subject	Natural Gas	en
dc.subject	Wiebe function	en
dc.title	Ανάπτυξη ημι-εμπειρικού μοντέλου καύσης για δίχρονο, ναυτικό κινητήρα διπλού καυσίμου, χαμηλής πίεσης	el
dc.title	Development of a semi-empirical combustion model for a dual fuel two-stroke low-pressure marine engine	en
heal.type	bachelorThesis
heal.classification	Ναυτική μηχανολογία	el
heal.language	en
heal.access	free
heal.recordProvider	ntua	el
heal.publicationDate	2019-12-19
heal.abstract	The “Dual-Fuel Engine” (DF) concept has gained grown popularity during the last years among both researchers and shipping companies as it provides a realistic way to meet the demands set by the recent and the upcoming emission regulations. In this scope, the marine engine manufacturing companies have developed several dual-fuel solutions of different types. In particular, firstly, there are the four-stroke, dual-fuel engines that operate as conventional four-stroke, diesel engines except that when in “dual-fuel mode” natural gas is used as main fuel and also the air-fuel mixture is ignited by a small amount of pilot, diesel fuel that is injected at the end of the compression stroke. As for the two stroke applications of this technology they are encountered in two types, the “high pressure” and the “low pressure”. In “high pressure”, two-stroke, DF engines, gas is injected into the compressed air at high pressure leading to a diffusion combustion that follows the “Diesel” cycle. On the other hand, in the “low pressure” version of the two-stroke DF engine the main fuel is injected earlier, at low pressures, leading to a lean burn, “Otto” combustion. In both cases, the start of the combustion is supported by diesel, pilot fuel injection at the Top Dead Center. The combustion process in dual-fuel engines is a phenomenon of high complexity that requires further research to be conducted to be better understood. So, in order to study such a phenomenon, a combustion model needs to be developed. In the present work, the produced model corresponds to the DF combustion of a two-stroke, low pressure, marine engine. In terms of modelling types, a zero-dimensional, semi-empirical approach was selected that represents the combustion as a heat release phenomenon with the use of a mathematical function whose parameters are calibrated by heat release data. In this work, a double-“Wiebe” function was utilized to describe the heat release process by dividing it into two separate parts, the main and the pilot fuel combustion. Wiebe function was selected as it is an analytical tool of high computational efficiency that is widely used in terms of performance prediction of internal combustion engines. As for the calibration of the model, it was based on validation data provided by the available literature (1). By evaluating the model using proper mathematical criteria and comparing its results to the validation data, it was found that it is able to make accurate predictions within its calibration range. The model fitting outcome led to conclusions that seem to be in good agreement with the recent results found in literature. In terms of “Ignition Delay” of the pilot fuel, it was found that it is reduced in cases of high engine loads and low overall equivalence ratios. Also, the “pre-ignition” phenomenon of the main fuel, meaning the spontaneous ignition of gas prior Page \| 3 to pilot flame front arrival, became more pronounced at high overall equivalence ratio and engine speed values and also at late pilot injection timing and early exhaust valve closing. Moreover, the combustion of both fuels is accelerated when load, equivalence ratio, engine speed and pilot injection angle are increased. In addition to the above conclusions, the present work indicates that the complex dual fuel combustion can be accurately represented by the relatively simple analytical Wiebe function and produce reliable outcomes. In fact, the program codes that have been created in the scope of developing the combustion model make up a useful and computational effective tool for the production of a combustion model for any DF engine even in high pressure or four stroke concepts provided that an adequate amount of trustworthy calibration data is available	en
heal.advisorName	Κυρτάτος, Νικόλαος	el
heal.committeeMemberName	Καϊκτσής, Λάμπρος	el
heal.committeeMemberName	Φούντη, Μαρία	el
heal.academicPublisher	Εθνικό Μετσόβιο Πολυτεχνείο. Σχολή Ναυπηγών Μηχανολόγων Μηχανικών. Τομέας Ναυτικής Μηχανολογίας. Εργαστήριο Ναυτικής Μηχανολογίας	el
heal.academicPublisherID	ntua
heal.numberOfPages	92 σ.
heal.fullTextAvailability	false