Mixture formation of OME3−5 and 1-Octanol in comparison with diesel-like Dodecane under ECN Spray A conditions

Strauß, Lukas; Riess, Sebastian; Wensing, Michael

doi:10.3389/fmech.2023.1083658

Cited by 2 publications

(2 citation statements)

References 20 publications

(28 reference statements)

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“…The macroscopic characteristics of the OME 3−5 fuel mix compared to OME 1 , n-dodecane, and hydrotreated vegetable oil (HVO) were reported in [15] showing a longer liquid length and shorter ignition delay for OME 3−5 compared to n-dodecane, despite its lower cetane number. The mixing process of OME 3−5 was analyzed in comparison to n-dodecane and 1-octanol [16]. All fuels proved to have very similar mass distributions, and the differences in equivalence ratio distributions were solely a consequence of the different air requirements for stoichiometric mixing of the oxygenated fuels.…”

Section: Introductionmentioning

confidence: 99%

LES and RANS Spray Combustion Analysis of OME3-5 and n-Dodecane

Wiesmann,

Nguyen,

Manin

et al. 2024

Energies

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Clean-burning oxygenated and synthetic fuels derived from renewable power, so-called e-fuels, are a promising pathway to decarbonize compression–ignition engines. Polyoxymethylene dimethyl ethers (PODEs or OMEs) are one candidate of such fuels with good prospects. Their lack of carbon-to-carbon bonds and high concentration of chemically bound oxygen effectively negate the emergence of polycyclic aromatic hydrocarbons (PAHs) and even their precursors like acetylene (C2H2), enabling soot-free combustion without the soot-NOx trade-off common for diesel engines. The differences in the spray combustion process for OMEs and diesel-like reference fuels like n-dodecane and their potential implications on engine applications include discrepancies in the observed ignition delay, the stabilized flame lift-off location, and significant deviations in high-temperature flame morphology. For CFD simulations, the accurate modeling and prediction of these differences between OMEs and n-dodecane proved challenging. This study investigates the spray combustion process of an OME3 − 5 mixture and n-dodecane with advanced optical diagnostics, Reynolds-Averaged Navier–Stokes (RANS), and Large-Eddy Simulations (LESs) within a constant-volume vessel. Cool-flame and high-temperature combustion were measured simultaneously via high-speed (50 kHz) imaging with formaldehyde (CH2O) planar laser-induced fluorescence (PLIF) representing the former and line-of-sight OH* chemiluminescence the latter. Both RANS and LES simulations accurately describe the cool-flame development process with the formation of CH2O. However, CH2O consumption and the onset of high-temperature reactions, signaled by the rise of OH* levels, show significant deviations between RANS, LES, and experiments as well as between n-dodecane and OME. A focus is set on the quality of the simulated results compared to the experimentally observed spatial distribution of OH*, especially in OME fuel-rich regions. The influence of the turbulence modeling is investigated for the two distinct ambient temperatures of 900 K and 1200 K within the Engine Combustion Network Spray A setup. The capabilities and limitations of the RANS simulations are demonstrated with the initial cool-flame propagation and periodic oscillations of CH2O formation/consumption during the quasi-steady combustion period captured by the LES.

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Section: Introductionmentioning

confidence: 99%

LES and RANS Spray Combustion Analysis of OME3-5 and n-Dodecane

Wiesmann,

Nguyen,

Manin

et al. 2024

Energies

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“…The measured particle number emissions were found to be smaller than for diesel. A detailed analysis of the influence of OME chain length on NO x emissions was given by Dworschak et al [10] on a single-cylinder diesel engine. A higher chain length was found to be beneficial in terms of NO x emissions with only little drawbacks on thermal efficiency.…”

Section: Introductionmentioning

confidence: 99%

Numerical study of novel OME1−6 combustion mechanism and spray combustion at changed ambient environments

Wiesmann,

Qiu,

Han

et al. 2024

Front. Energy

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For a climate-neutral future mobility, the so-called e-fuels can play an essential part. Especially, oxygenated e-fuels containing oxygen in their chemical formula have the additional potential to burn with significantly lower soot levels. In particular, polyoxymethylene dimethyl ethers or oxymethylene ethers (PODEs or OMEs) do not contain carbon-carbon bonds, prohibiting the production of soot precursors like acetylene (C2H2). These properties make OMEs a highly interesting candidate for future climate-neutral compression-ignition engines. However, to fully leverage their potential, the auto-ignition process, flame propagation, and mixing regimes of the combustion need to be understood. To achieve this, efficient oxidation mechanisms suitable for computational fluid dynamics (CFD) calculations must be developed and validated. The present work aims to highlight the improvements made by developing an adapted oxidation mechanism for OME1−6 and introducing it into a validated spray combustion CFD model for OMEs. The simulations were conducted for single- and multi-injection patterns, changing ambient temperatures, and oxygen contents. The results were validated against high-pressure and high-temperature constant-pressure chamber experiments. OH*-chemiluminescence measurements accomplished the characterization of the auto-ignition process. Both experiments and simulations were conducted for two different injectors. Significant improvements concerning the prediction of the ignition delay time were accomplished while also retaining an excellent agreement for the flame lift-off length. The spatial zones of high-temperature reaction activity were also affected by the adaption of the reaction kinetics. They showed a greater tendency to form OH* radicals within the center of the spray in accordance with the experiments.

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Mixture formation of OME3−5 and 1-Octanol in comparison with diesel-like Dodecane under ECN Spray A conditions

Cited by 2 publications

References 20 publications

LES and RANS Spray Combustion Analysis of OME3-5 and n-Dodecane

LES and RANS Spray Combustion Analysis of OME3-5 and n-Dodecane

Numerical study of novel OME1−6 combustion mechanism and spray combustion at changed ambient environments

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