Influence of dimethyl ether and diethyl ether addition on the flame structure and pollutant formation in premixed iso-octane flames

Zeng, Meirong; Wullenkord, Julia; Graf, Isabelle; Kohse‐Höinghaus, Katharina

doi:10.1016/j.combustflame.2017.05.028

Cited by 31 publications

(31 citation statements)

References 62 publications

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“…Additionally, DME can be produced from diverse sources such as natural gas, coal gasification, oil residues, and biomass [20]. The possibility of reduction of harmful emissions with DME addition was investigated in various laboratory scale flames and engine studies [27][28][29][30]. The flame structure and species composition with DME blending in iso-octane fuel was investigated experimentally and numerically in premixed low-pressure flames, and they revealed that the addition of DME decreased the formation of soot precursors while enhanced the production of formaldehyde [29].…”

Section: Introductionmentioning

confidence: 99%

“…The possibility of reduction of harmful emissions with DME addition was investigated in various laboratory scale flames and engine studies [27][28][29][30]. The flame structure and species composition with DME blending in iso-octane fuel was investigated experimentally and numerically in premixed low-pressure flames, and they revealed that the addition of DME decreased the formation of soot precursors while enhanced the production of formaldehyde [29]. However, in counterflow diffusion flames, a small amount of DME addition to ethylene fuel enhances the formation of small aromatic precursors and soot particles in the pyrolysis region based on laserinduced fluorescence and incandescence techniques [22,24].…”

Section: Introductionmentioning

confidence: 99%

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Effect of dimethyl ether (DME) addition on sooting limits in counterflow diffusion flames of ethylene at elevated pressures

Amin

Liu

et al. 2018

Combustion and Flame

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The effects of dimethyl ether (DME) addition to ethylene fuel on sooting tendencies with varying pressure were investigated in counterflow diffusion flames by using a laser scattering technique. Sooting limit maps were determined in the fuel (XF) and oxygen (XO) mole fraction plane, separating sooting and non-sooting regions. The results showed that when DME is mixed to ethylene, the sooting region was appreciably shrank, especially in the cases of soot formation/oxidation (SFO) flames as compared with the cases of soot formation (SF) flames. This indicated an inhibiting role of DME on sooting. An interesting observation was that the critical XO required for sooting initially decreased and then increased with the DME mixing ratio to ethylene β for the cases of SF flames, exhibiting a non-monotonic behavior. This implied a promoting role of DME on sooting when small amount of DME is mixed to ethylene. As the pressure increased, the sooting region generally expanded. Specifically, the range of β in promoting soot formation extended with pressure. This implies that a strategy in reducing soot by adding DME to ethylene at high pressures required a large amount of DME addition. To interpret the observed phenomena, kinetic simulations including reaction pathway and sensitivity analyses were conducted with the opposed-flow flames model using the KAUST-Aramco PAH Mech. The results showed that the thermal effect of DME addition on sooting tendency monotonically decreases with . The chemical effect was found to be the main contributor to the DME addition effect on sooting tendency, resulting in the non-monotonic sooting limt behavior. The pathway analysis showed the role of methyl radicals generated from DME promoted incipient benzene ring formtion when small amount of DME was added, which can be attributed to the soot promoting role of DME addition for small β.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of dimethyl ether (DME) addition on sooting limits in counterflow diffusion flames of ethylene at elevated pressures

Amin

Liu

et al. 2018

Combustion and Flame

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“…A major disadvantage of this technique is the difficulty to distinguish between the different isomer with the results from the EI‐MBMS experiment. For the qualitative interpretation of EI‐MBMS data, some previous researchers 30,33,34 took indications for the prevalence of respective isomers from the literature, which made some achievements in non‐PAC cases. As mentioned in Section 1, by comparison between PAC cases and non‐PAC cases for n ‐heptane, Vanhove et al 25 .…”

Section: Resultsmentioning

confidence: 99%

MBMS study on plasma‐assisted low‐temperature oxidation of n‐heptane and iso‐octane in a flow reactor

Liao

Chen

Liu

et al. 2020

Int J of Chemical Kinetics

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Nonequilibrium plasma has a great potential in the lean combustion of gasoline engines. However, fundamental studies on plasma‐assisted combustion on gasoline components are limited. In the present study, Low‐temperature oxidation behaviors for n‐heptane and iso‐octane in a plasma flow reactor were investigated. Species measurements were performed at room temperature and low pressure of 40 mbar using the electron ionization molecular‐beam mass spectrometry (EI‐MBMS). A total of 72 and 57 species were quantified in n‐heptane and iso‐octane oxidation, respectively. Based on measured species data, reaction networks of n‐heptane and iso‐octane in the plasma system were discussed. Particularly, some typical low‐temperature intermediates, such as cyclic ethers, diones, and ketohydroperoxides, were observed, suggesting the applicability of the classical low‐temperature reaction scheme in the plasma system of large hydrocarbons. The results indicate that the major role of plasma discharge on the low‐temperature oxidation of large hydrocarbons is either to breakdown large fuel molecules or to accelerate the chain initiation reactions. We also investigated the parametric effects of voltage, frequency, and residence time on the species pools, and found that the increase of these parameters leads to higher production of intermediates. The whole system reactivity was most sensitive to the plasma voltage. The difference between plasma frequency and residence time on the species formation was found. Moreover, some highly temperature‐sensitive reactions, such as the RO2 → QOOH, proceed at very low temperatures (around 340 K) in the plasma system, which was potentially attributed to the additional energy from plasma‐generated species.

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“…Particularly valuable results can be obtained from the systematic variation of the fuel structure motives (e.g. saturation and branching degree) in studies of hydrocarbon-oxygenate fuel mixtures, as reported for the oxidation of hydrocarbon base fuels of different chain length, blended with ethers, alcohols, or esters [50][51][52][53]114]. Interactive effects have been observed in particular in the low-temperature reactivity for mixtures of n-pentane with DME or ethanol as reported by Jin et al [51].…”

Section: Hydrocarbon-oxygenate Fuel Blendsmentioning

confidence: 97%

“…While chemical reaction mechanisms predicting combustion behavior and exhaust composition, especially regarding non-regulated species-specific contributions to the HC fraction, are in a reasonable state of development for conventional petroleum-based hydrocarbon fuels [28][29][30][31][32] and their application in conventional engines, advanced engine concepts using low-temperature reactions [44][45][46][47] and biofuels or biofuel-hydrocarbon mixtures [38,40,[48][49][50][51][52][53] add chemical complexity. Further chemical problems related to the respective fuel-engine system can be mentioned only in passing here, namely concepts for highly efficient exhaust gas after treatment [54][55][56].…”

Section: Fuel-specific Reactivity Combustion Models and Validationmentioning

confidence: 99%

A new era for combustion research

Kohse‐Höinghaus

2019

Pure and Applied Chemistry

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Current topics in combustion chemistry include aspects of a changing fuel spectrum with a focus on reducing emissions and increasing efficiency. This article is intended to provide an overview of selected recent work in combustion chemistry, especially addressing reaction pathways from fuel decomposition to emissions. The role of the molecular fuel structure will be emphasized for the formation of certain regulated and unregulated species from individual fuels and their mixtures, exemplarily including fuel compounds such as alkanes, alkenes, ethers, alcohols, ketones, esters, and furan derivatives. Depending on the combustion conditions, different temperature regimes are important and can lead to different reaction classes. Laboratory reactors and flames are prime sources and targets from which such detailed chemical information can be obtained and verified with a number of advanced diagnostic techniques, often supported by theoretical work and simulation with combustion models developed to transfer relevant details of chemical mechanisms into practical applications. Regarding the need for cleaner combustion processes, some related background and perspectives will be provided regarding the context for future chemistry research in combustion energy science.

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Influence of dimethyl ether and diethyl ether addition on the flame structure and pollutant formation in premixed iso-octane flames

Cited by 31 publications

References 62 publications

Effect of dimethyl ether (DME) addition on sooting limits in counterflow diffusion flames of ethylene at elevated pressures

Effect of dimethyl ether (DME) addition on sooting limits in counterflow diffusion flames of ethylene at elevated pressures

MBMS study on plasma‐assisted low‐temperature oxidation of n‐heptane and iso‐octane in a flow reactor

A new era for combustion research

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