Studying the effects of hydrogen addition on the second-law balance of a biogas-fuelled spark ignition engine by use of a quasi-dimensional multi-zone combustion model

Kakopoulos, CD; Michos, CN; Giakoumis, EG

dc.contributor.author	Kakopoulos, CD	en
dc.contributor.author	Michos, CN	en
dc.contributor.author	Giakoumis, EG	en
dc.date.accessioned	2014-03-01T01:29:16Z
dc.date.available	2014-03-01T01:29:16Z
dc.date.issued	2008	en
dc.identifier.issn	0954-4070	en
dc.identifier.uri	https://dspace.lib.ntua.gr/xmlui/handle/123456789/19189
dc.subject	Biogas	en
dc.subject	Hydrogen enrichment	en
dc.subject	Irreversibilities	en
dc.subject	Quasi-dimensional multi-zone combustion model	en
dc.subject	Second-law analysis	en
dc.subject	Spark ignition engine	en
dc.subject.classification	Engineering, Mechanical	en
dc.subject.classification	Transportation Science & Technology	en
dc.subject.other	Biogas	en
dc.subject.other	Combustion	en
dc.subject.other	Computational fluid dynamics	en
dc.subject.other	Electric sparks	en
dc.subject.other	Engine cylinders	en
dc.subject.other	Engines	en
dc.subject.other	Hydrocarbons	en
dc.subject.other	Hydrogen	en
dc.subject.other	Laws and legislation	en
dc.subject.other	Loudspeakers	en
dc.subject.other	Modal analysis	en
dc.subject.other	Nonmetals	en
dc.subject.other	Nuclear fuel reprocessing	en
dc.subject.other	Smoke	en
dc.subject.other	Thermochemistry	en
dc.subject.other	Thermodynamics	en
dc.subject.other	Hydrogen enrichment	en
dc.subject.other	Irreversibilities	en
dc.subject.other	Quasi-dimensional multi-zone combustion model	en
dc.subject.other	Second-law analysis	en
dc.subject.other	Spark ignition engine	en
dc.subject.other	Ignition	en
dc.title	Studying the effects of hydrogen addition on the second-law balance of a biogas-fuelled spark ignition engine by use of a quasi-dimensional multi-zone combustion model	en
heal.type	journalArticle	en
heal.identifier.primary	10.1243/09544070JAUTO947	en
heal.identifier.secondary	http://dx.doi.org/10.1243/09544070JAUTO947	en
heal.language	English	en
heal.publicationDate	2008	en
heal.abstract	Although a first-law analysis can show the improvement that hydrogen addition impacts on the performance of a biogas-fuelled spark-ignition (SI) engine, additional benefits can be revealed when the second law of thermodynamics is brought into perspective. It is theoretically expected that hydrogen enrichment in biogas can increase the second-law efficiency of engine operation by reducing the combustion-generated irreversibilities, because of the fundamental differences in the mechanism of entropy generation between hydrogen and traditional hydrocarbon combustion. In this study, an experimentally validated closed-cycle simulation code, incorporating a quasi-dimensional multi-zone combustion model that is based on the combination of turbulent entrainment theory and flame stretch concepts for the prediction of burning rates, is further extended to include second-law analysis for the purpose of quantifying the respective improvements. The analysis is applied for a single-cylinder homogeneous charge SI engine, fuelled with biogas-hydrogen blends, with up to 15 vol% hydrogen in the fuel mixture, when operated at 1500r/min, wide-open throttle, fuel-to-air equivalence ratio of 0.9, and ignition timing of 20° crank angle before top dead centre. Among the major findings derived from the second-law balance during the closed part of the engine cycle is the increase in the second-law efficiency from 40.85 per cent to 42.41 per cent with hydrogen addition, accompanied by a simultaneous decrease in the combustion irreversibilities from 18.25 per cent to 17.18 per cent of the total availability of the charge at inlet valve closing. It is also illustrated how both the increase in the combustion temperatures and the decrease in the combustion duration with increasing hydrogen content result in a reduction in the combustion irreversibilities. The degree of thermodynamic perfection of the combustion process from the second-law point of view is quantified by using two (differently defined) combustion exergetic efficiencies, whose maximum values during the combustion process increase with hydrogen enrichment from 49.70 per cent to 53.45 per cent and from 86.01 per cent to 87.33 per cent, respectively. © IMechE 2008.	en
heal.publisher	PROFESSIONAL ENGINEERING PUBLISHING LTD	en
heal.journalName	Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering	en
dc.identifier.doi	10.1243/09544070JAUTO947	en
dc.identifier.isi	ISI:000262096500023	en
dc.identifier.volume	222	en
dc.identifier.issue	11	en
dc.identifier.spage	2065	en
dc.identifier.epage	2084	en