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Flammability conditions for ultra-lean hydrogen premixed combustion based on flame-ball analyses

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dc.affiliation.dptoUC3M. Departamento de Ingeniería Térmica y de Fluidoses
dc.affiliation.grupoinvUC3M. Grupo de Investigación: Mecánica de Fluidoses
dc.contributor.authorFernández Tarrazo, Eduardo Antonio
dc.contributor.authorSánchez Pérez, Antonio Luis
dc.contributor.authorWilliams, Forman A.
dc.contributor.authorLiñán Martínez, Amable
dc.date.accessioned2014-02-04T15:12:38Z
dc.date.available2014-02-04T15:12:38Z
dc.date.issued2012-01
dc.descriptionProceeding of: 10th International Conference on Clean Energy 2010, 15-17 September 2010, Famagusta, North Cyprusen
dc.description.abstractIt has been reasoned that the structures of strongly cellular flames in very lean mixtures approach an array of flame balls, each burning as if it were isolated, thereby indicating a connection between the critical conditions required for existence of steady flame balls and those necessary for occurrence of self-sustained premixed combustion. This is the starting assumption of the present study, in which structures of near-limit steady sphericosymmetrical flame balls are investigated with the objective of providing analytic expressions for critical combustion conditions in ultra-lean hydrogen-oxygen mixtures diluted with N2 and water vapor. If attention were restricted to planar premixed flames, then the lean-limit mole fraction of H2 would be found to be roughly ten percent, more than twice the observed flammability limits, thereby emphasizing the relevance of the flame-ball phenomena. Numerical integrations using detailed models for chemistry and radiation show that a onestep chemical-kinetic reduced mechanism based on steady-state assumptions for all chemical intermediates, together with a simple, optically thin approximation for water-vapor radiation, can be used to compute near-limit fuel-lean flame balls with excellent accuracy. The previously developed one-step reaction rate includes a crossover temperature that determines in the first approximation a chemical-kinetic lean limit below which combustion cannot occur, with critical conditions achieved when the diffusion-controlled radiation-free peak temperature, computed with account taken of hydrogen Soret diffusion, is equal to the crossover temperature. First-order corrections are found by activation-energy asymptotics in a solution that involves a near-field radiation-free zone surrounding a spherical flame sheet, together with a far-field radiation-conduction balance for the temperature profile. Different scalings are found depending on whether or not the surrounding atmosphere contains water vapor, leading to different analytic expressions for the critical conditions for flame-ball existence, which give results in very good agreement with those obtained by detailed numerical computations. The one-step chemistry employed in the present work, which involves a non-Arrhenius rate having a cutoff at the crossover temperature, applies with excellent accuracy to the description of lean premixed hydrogen-air combustion, i.e, for f(0:5 at atmospheric pressure, and could be used for instance in the numerical simulation of the propagation of curved or cellularflames in ultra-lean reactive atmospheres, of interest for safety analyses related to the storage, transport, and handling of hydrogen.en
dc.description.sponsorshipThis work was supported by the Comunidad de Madrid through project #P2009/ENE-1597. The first three authors also acknowledge support from the Spanish MCINN through projects # ENE2008-06515 and CSD2010-00011.en
dc.format.extent13es
dc.format.mimetypeapplication/pdf
dc.identifier.bibliographicCitationInternational Journal of Hydrogen Energy, Vol. 37, nº 2, pp. 1813- 1825en
dc.identifier.doi10.1016/j.ijhydene.2011.10.037
dc.identifier.issn0360-3199
dc.identifier.publicationfirstpage1813es
dc.identifier.publicationissue2es
dc.identifier.publicationlastpage1825es
dc.identifier.publicationtitleInternational Journal of Hydrogen Energyen
dc.identifier.publicationvolume37es
dc.identifier.urihttps://hdl.handle.net/10016/18203
dc.identifier.uxxiAR/0000009812
dc.language.isoenges
dc.publisherElsevieres
dc.relation.eventdate15-17 September 2010en
dc.relation.eventplaceFamagusta, North Cyprusen
dc.relation.eventtitle10th International Conference on Clean Energy 2010en
dc.relation.projectIDComunidad de Madrid. S2009/ENE-1597/HYSYCOMB
dc.relation.publisherversionhttp://dx.doi.org/10.1016/j.ijhydene.2011.10.037
dc.rights© 2011, Hydrogen Energy Publicationsen
dc.rights.accessRightsopen accessen
dc.subject.ecienciaEnergías Renovableses
dc.subject.otherHydrogenen
dc.subject.otherFlammability limiten
dc.subject.otherUltra-lean combustionen
dc.subject.otherReduced chemistryen
dc.subject.otherFlame ballsen
dc.titleFlammability conditions for ultra-lean hydrogen premixed combustion based on flame-ball analysesen
dc.typeconference proceedings*
dc.type.hasVersionAM*
dspace.entity.typePublication
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