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Verification of diesel spray ignition phenomenon in dual-fuel diesel-piloted premixed natural gas engine

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Verification of diesel spray ignition phenomenon in dual-fuel diesel-piloted premixed natural gas engine

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dc.contributor.author Niki, Yoichi es_ES
dc.contributor.author Rajasegar, Rajavasanth es_ES
dc.contributor.author Li, Zheming es_ES
dc.contributor.author Musculus, Mark P.B. es_ES
dc.contributor.author García-Oliver, José M es_ES
dc.contributor.author Takasaki, Koji es_ES
dc.date.accessioned 2022-11-24T19:03:43Z
dc.date.available 2022-11-24T19:03:43Z
dc.date.issued 2022-02 es_ES
dc.identifier.issn 1468-0874 es_ES
dc.identifier.uri http://hdl.handle.net/10251/190184
dc.description.abstract [EN] Dual-fuel (DF) engines, in which premixed natural gas and air in an open-type combustion chamber is ignited by diesel-fuel pilot sprays, have been more popular for marine use than pre-chamber spark ignition (PCSI) engines because of their superior durability. However, control of ignition and combustion in DF engines is more difficult than in PCSI engines. In this context, this study focuses on the ignition stability of n-heptane pilot-fuel jets injected into a compressed premixed charge of natural gas and air at low-load conditions. To aid understanding of the experimental data, chemical-kinetics simulations were carried out in a simplified engine-environment that provided insight into the chemical effects of methane (CH4) on pilot-fuel ignition. The simulations reveal that CH4 has an effect on both stages of n-heptane autoignition: the small, first-stage, cool-flame-type, low-temperature ignition (LTI) and the larger, second-stage, high-temperature ignition (HTI). As the ratio of pilot-fuel to CH4 entrained into the spray decreases, the initial oxidization of CH4 consumes the OH radicals produced by pilot-fuel decomposition during LTI, thereby inhibiting its progression to HTI. Using imaging diagnostics, the spatial and temporal progression of LTI and HTI in DF combustion are measured in a heavy-duty optical engine, and the imaging data are analyzed to understand the cause of severe fluctuations in ignition timing and combustion completeness at low-load conditions. Images of cool-flame and hydroxyl radical (OH*) chemiluminescence serve as indicators of LTI and HTI, respectively. The cycle-to-cycle and spatial variation in ignition extracted from the imaging data are used as key metrics of comparison. The imaging data indicate that the local concentration of the pilot-fuel and the richness of the surrounding natural-gas air mixture are important for LTI and HTI, but in different ways. In particular, higher injection pressures and shorter injection durations increase the mixing rate, leading to lower concentrations of pilot-fuel more quickly, which can inhibit HTI even as LTI remains relatively robust. Decreasing the injection pressure from 80 MPa to 40 MPa and increasing the injection duration from 500 mu s to 760 mu s maintained constant pilot-fuel mass, while promoting robust transition from LTI to HTI by effectively slowing the mixing rate. This allows enough residence time for the OH radicals, produced by the two-stage ignition chemistry of the pilot-fuel, to accelerate the transition from LTI to HTI before being consumed by CH4 oxidation. Thus from a practical perspective, for a premixed natural gas fuel-air equivalence-ratio, it is possible to improve the "stability" of the combustion process by solely manipulating the pilot-fuel injection parameters while maintaining constant mass of injected pilot-fuel. This allows for tailoring mixing trajectories to offset changes in fuel ignition chemistry, so as to promote a robust transition from LTI to HTI by changing the balance between the local concentration of the pilot-fuel and richness of the premixed natural gas and air. This could prove to be a valuable tool for combustion design to improve fuel efficiency or reduce noise or perhaps even reduce heat-transfer losses by locating early combustion away from in-cylinder walls. es_ES
dc.description.sponsorship This research was sponsored in part by the U.S. Department of Energy (DOE) Office of Energy Efficiency and Renewable Energy (EERE). Optical engine experiments were conducted at the Combustion Research Facility of Sandia National Laboratories in Livermore, CA. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy's National Nuclear Security Administration (NNSA) under contract DE-NA0003525. es_ES
dc.language Inglés es_ES
dc.publisher SAGE Publications es_ES
dc.relation.ispartof International Journal of Engine Research es_ES
dc.rights Reserva de todos los derechos es_ES
dc.subject Dual-fuel engines es_ES
dc.subject Lean-premixed natural gas combustion es_ES
dc.subject Diesel es_ES
dc.subject Two-stage autoignition es_ES
dc.subject Cool-flame chemiluminescence es_ES
dc.subject OH* chemiluminescence es_ES
dc.subject Ignition delay es_ES
dc.subject Chemical kinetics es_ES
dc.subject.classification MAQUINAS Y MOTORES TERMICOS es_ES
dc.title Verification of diesel spray ignition phenomenon in dual-fuel diesel-piloted premixed natural gas engine es_ES
dc.type Artículo es_ES
dc.identifier.doi 10.1177/1468087420983060 es_ES
dc.relation.projectID info:eu-repo/grantAgreement/DOE//DE-NA0003525/ es_ES
dc.rights.accessRights Abierto es_ES
dc.contributor.affiliation Universitat Politècnica de València. Escuela Técnica Superior de Ingeniería del Diseño - Escola Tècnica Superior d'Enginyeria del Disseny es_ES
dc.description.bibliographicCitation Niki, Y.; Rajasegar, R.; Li, Z.; Musculus, MP.; García-Oliver, JM.; Takasaki, K. (2022). Verification of diesel spray ignition phenomenon in dual-fuel diesel-piloted premixed natural gas engine. International Journal of Engine Research. 23(2):180-197. https://doi.org/10.1177/1468087420983060 es_ES
dc.description.accrualMethod S es_ES
dc.relation.publisherversion https://doi.org/10.1177/1468087420983060 es_ES
dc.description.upvformatpinicio 180 es_ES
dc.description.upvformatpfin 197 es_ES
dc.type.version info:eu-repo/semantics/publishedVersion es_ES
dc.description.volume 23 es_ES
dc.description.issue 2 es_ES
dc.relation.pasarela S\435462 es_ES
dc.contributor.funder U.S. Department of Energy es_ES
dc.contributor.funder Office of Energy Efficiency and Renewable Energy, EEUU es_ES


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