Auto-ignition of oxymethylene ethers (OMEn, n = 2–4) as promising synthetic e-fuels from renewable electricity: shock tube experiments and automatic mechanism generation

Cai, Liming; Jacobs, Sascha; Langer, Raymond; Lehn, Florian vom; Heufer, Karl Alexander; Pitsch, Heinz

doi:10.1016/j.fuel.2019.116711

Cited by 77 publications

(111 citation statements)

References 45 publications

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“…The favored oxidation pathway at the intermediate temperature starts with H-atom abstraction from the primary ("1") fuel site. 13 The chemical potentials of the subsequently formed R1OȮ radicals are presently larger than previously predicted and therefore shift theṘ1 + O 2 to R1OȮ equilibrium toward theṘ1 + O 2 side. In addition, the chemical potentials of the correspondingQOOH radicals were increased more than that of R1OȮ, which shifts the equilibria of the internal hydrogen shift reactions toward R1OȮ.…”

Section: Ignition Delay Timesmentioning

confidence: 88%

“…At these low F I G U R E 2 Ignition delay times for OME2 and OME3. Experimental data and chemical kinetic model from Cai et al 13 temperatures, there are essentially no reactions competing to the low-temperature chain branching channels and the reactivity-governing reactions remain the same. In the midtemperature regime (650 K < T <1100 K), the updated thermochemistry has a major reactivity inhibiting effect.…”

Section: Ignition Delay Timesmentioning

confidence: 97%

“…47 The recent OME2-OME4 chemical kinetic model of Cai et al 13 is used, with the thermochemistry of all OME2-and OME3-specific species being recalculated with the present groups. Note that in the original model, 13 fuelspecific thermochemistry data were determined based on the GA values implemented in RMG. 24 Figure 2 shows the resulting model predictions with (w/) and without (w/o) the present thermochemistry in comparison to the shock tube data provided by Cai et al 13 In the low-temperature regime (T < 650 K), the updated thermochemistry has a marginal effect.…”

Section: Ignition Delay Timesmentioning

confidence: 99%

“…Note that in the original model, 13 fuelspecific thermochemistry data were determined based on the GA values implemented in RMG. 24 Figure 2 shows the resulting model predictions with (w/) and without (w/o) the present thermochemistry in comparison to the shock tube data provided by Cai et al 13 In the low-temperature regime (T < 650 K), the updated thermochemistry has a marginal effect. At these low F I G U R E 2 Ignition delay times for OME2 and OME3.…”

Section: Ignition Delay Timesmentioning

confidence: 99%

“…For OMEs, such detailed chemical kinetic models have been developed for DMM [8][9][10][11] and larger OMEs. 12,13 These models were partly based on ab initio kinetics and thermochemistry for some fuel-related reactions and species of the DMM combustion system. Kopp et al 14 computed DMM H-atom abstraction and unimolecular radical reaction rate coefficients and calculated the thermochemistry of DMM, the primary fuel radicals, the peroxy species (ROȮ), the respective parent hydroperoxide species (ROOH), and the products of the internal hydrogen abstraction of ROȮ (QOOH).…”

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confidence: 99%

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Updated thermochemistry for renewable transportation fuels: New groups and group values for acetals and ethers, their radicals, and peroxy species

Döntgen

Kopp

Lehn

et al. 2020

Int J of Chemical Kinetics

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We present new groups and group values for the gas-phase thermochemistry of ethers, polyethers, and acetals suited for combustion modeling. Our investigation comprises fuel species, their primary radicals, peroxy radicals, and hydroperoxide species. In total, 45 species are used for the parameterization of 14 groups, six of which are newly introduced here. Presently, calculated thermochemistry at the DLPNO-CCSD(T)/CBS(cc-pVTZ, cc-PVQZ) // B3LYP-D3BJ/def2-TZVP level of theory is combined with thermochemistry from the literature. Validation of the new group values against the quantum mechanical results gives deviations of 1.22 kcal/mol, 2.36 cal/(mol⋅K), and 1.20 cal/(mol⋅K) for heats of formation, standard entropies, and heat capacities, respectively. The new thermochemistry is tested with a recent OME2 and OME3 chemical kinetic model, which shows large sensitivities to the updated values in the intermediate temperature regime. This highlights the importance of using updated thermochemistry in future chemical kinetic modeling studies of oxygenated methyl ethers (OMEs) and OMErelated structures. K E Y W O R D S ab initio thermochemistry, group additivity theory, oxymethylene ethers 1 INTRODUCTION Oxygenated methyl ethers (OMEs) are interesting fuel candidates for several reasons. OMEs improve the soot-NO trade-off 1 when being used as diesel fuel additives and the smallest OME, dimethoxy methane (DMM), has already been tested as pure fuel. 2 In addition, it was found that carbon monoxide 3 and noise emissions 4 are reduced when blending diesel with DMM. Furthermore, This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

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Section: Ignition Delay Timesmentioning

confidence: 88%

Section: Ignition Delay Timesmentioning

confidence: 97%

Section: Ignition Delay Timesmentioning

confidence: 99%

Section: Ignition Delay Timesmentioning

confidence: 99%

mentioning

confidence: 99%

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Updated thermochemistry for renewable transportation fuels: New groups and group values for acetals and ethers, their radicals, and peroxy species

Döntgen

Kopp

Lehn

et al. 2020

Int J of Chemical Kinetics

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Numerical assessment of polyoxymethylene dimethyl ether (OME3) injection timing in compression ignition engine

Marković,

Jurić,

Šošić

et al. 2023

Clean Techn Environ Policy

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

Wiesmann,

Han,

Qiu

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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Auto-ignition of oxymethylene ethers (OMEn, n = 2–4) as promising synthetic e-fuels from renewable electricity: shock tube experiments and automatic mechanism generation

Cited by 77 publications

References 45 publications

Updated thermochemistry for renewable transportation fuels: New groups and group values for acetals and ethers, their radicals, and peroxy species

Updated thermochemistry for renewable transportation fuels: New groups and group values for acetals and ethers, their radicals, and peroxy species

Numerical assessment of polyoxymethylene dimethyl ether (OME3) injection timing in compression ignition engine

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

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