Impact of branched structures on cycloalkane ignition in a motored engine: Detailed product and conformational analyses

Kang, Dongil; Lilik, Gregory K.; Dillstrom, V.T.; Agudelo, John R.; Lapuerta, Magı́n; Al-Qurashi, Khalid; Boehman, André L.

doi:10.1016/j.combustflame.2014.09.009

Cited by 30 publications

(22 citation statements)

References 33 publications

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“…Their results showed that increasing branching decreases ignition reactivity of cycloparaffins. They [26] also performed a similar study on diisobutylene addition to n-heptane/iso-octane mixtures, demonstrating the combined effects of branching and unsaturation on reducing ignition reactivity.…”

Section: Introductionmentioning

confidence: 90%

Effects of methyl substitution on the auto-ignition of C16 alkanes

Lapuerta

Hernández

Sarathy

2016

Combustion and Flame

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The autoignition quality of diesel fuels, quantified by their Cetane Number or Derived Cetane Number (DCN), is a critical design property to consider when producing and upgrading synthetic paraffinic fuels. It is well known that autoignition characteristics of paraffinic fuels depend on their degree of methyl substitution. However, there remains a need to study the governing chemical functionalities contributing to such ignition characteristics, especially in the case of partially branched ones, which have not been studied in detail. In this work, the autoignition of 2,6,10-trimethyltridecane has been compared with the reference hydrocarbons used for cetane number determination, i.e. n-hexadecane and heptamethylnonane, all of them being C16 isomers. Results from a constant-volume combustion chamber under different pressure and temperature initial conditions showed that the ignition delay time for both cool flame and main combustion events increased less from n-hexadecane to trimethyltridecane than from trimethyltridecane to heptamethylnonane. Additional experimental results from blends of these hydrocarbons, together with kinetic modelling, showed that autoignition times and combustion rates were correlated to the concentration of the functional groups indicative of methyl substitution, although not in a linear manner. When the concentration of these functional groups decreased, the first stage OH radical concentration increased and ignition delay times decreased, whereas when their concentration increased, H 2 O 2 production was slower and ignition was retarded. Contrary to the ignition delay times, DCN was correlated linearly with functional groups, thus homogenizing the range of values and clarifying the differences between fuels.

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Section: Introductionmentioning

confidence: 90%

Effects of methyl substitution on the auto-ignition of C16 alkanes

Lapuerta

Hernández

Sarathy

2016

Combustion and Flame

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“…Recent efforts have also targeted jet fuels. Chemical kinetic models are typically formulated based on data from a variety of sources, including rapid compression machines (RCMs) [39], motored or skip-fired engines [40], flow/jet reactors [41,42], and shock tubes [43].…”

Section: Autoignition Chemistrymentioning

confidence: 99%

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Goldsborough

Hochgreb

Vanhove

et al. 2017

Progress in Energy and Combustion Science

206

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Rapid compression machines (RCMs) are widely-used to acquire experimental insights into fuel autoignition and pollutant formation chemistry, especially at conditions relevant to current and future combustion technologies. RCM studies emphasize important experimental regimes, characterized by lowto intermediate-temperatures (600-1200 K) and moderate to high pressures (5-80 bar). At these conditions, which are directly relevant to modern combustion schemes including low temperature combustion (LTC) for internal combustion engines and dry low emissions (DLE) for gas turbine engines, combustion chemistry exhibits complex and experimentally challenging behaviors such as the chemistry attributed to cool flame behavior and the negative temperature coefficient regime. Challenges for studying this regime include that experimental observations can be more sensitive to coupled physicalchemical processes leading to phenomena such as mixed deflagrative/autoignitive combustion. Experimental strategies which leverage the strengths of RCMs have been developed in recent years to make RCMs particularly well suited for elucidating LTC and DLE chemistry, as well as convolved physicalchemical processes. Specifically, this work presents a review of experimental and computational efforts applying RCMs to study autoignition phenomena, and the insights gained through these efforts. A brief history of RCM development is presented towards the steady improvement in design, characterization, instrumentation and data analysis. Novel experimental approaches and measurement techniques, coordinated with computational methods are described which have expanded the utility of RCMs beyond empirical studies of explosion limits to increasingly detailed understanding of autoignition chemistry and the role of physical-chemical interactions. Fundamental insight into the autoignition chemistry of specific fuels is described, demonstrating the extent of knowledge of low-temperature chemistry derived from RCM studies, from simple hydrocarbons to multi-component blends and full-boiling range fuels. Emerging needs and further opportunities are suggested, including investigations of under-explored fuels and the implementation of increasingly higher fidelity diagnostics.

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“…As the study of cycloalkanes, focusing on their molecular preferences, conformational behaviors, and relative energies, has long been a topic of interest for chemistry and some interrelated application, they have been investigated by theoretical calculations and experimental measurement [1‐11]. The adopted experimental methods briefly include X‐ray diffraction, Raman, infrared, and NMR spectrum detection, [9, 11‐14] and theoretical approaches contain ab initio, molecular force field, and dynamical density functional theory [7, 8, 10, 15].…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, one thing should be emphasized that the explorations of distinguishable geometric structures and interconversion mechanisms for substituted cycloalkanes are of great importance in organic and combustion chemistries demonstrated by the proceeding studies [2, 3, 18, 26, 27]. Supported by conformational analysis, Yang et al [3, 26] gained insight into the role of steric structures for several cycloalkanes in their low temperature oxidation chemistry by ab initio calculations and ignition experiment in a motored engine.…”

Section: Introductionmentioning

confidence: 99%

“…They proposed that the important 1,4 and 1,5 H‐migrations show strong structure dependence on such distinct conformers by inhibiting or triggering chain branching. Furthermore, Kang et al [2] revealed that the reactivity of ethylcyclohexane is higher than its isomers 1,2‐DMCH and 1,3‐DMCH, resulting from its conformational structures are more viable for 1,5 H‐migration in a modified CFR engine. Davis et al [27] computed kinetic parameters for 1,2 to 1,6 H‐migrations originated from various conformers of methyl‐ and ethylcyclohexyl radicals.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Computational study of inversion‐topomerization pathways in 1,3‐dimethylcyclohexane and 1,4‐dimethylcyclohexane: Ab initio conformational analysis

Bian

Zhang

Wang

et al. 2021

Int J of Quantum Chemistry

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This work concerns the special conformational behaviors for di‐substituted cyclohexanes that inherently depend on spatial orientations of side chains in flexible cyclic ring. The 1,3‐dimethylcyclohexane and 1,4‐dimethylcyclohexane in both cis‐ and trans‐configurations were focused here to unravel their inversion‐topomerization mechanisms. Full geometry optimizations were separately performed at B3LYP/6‐311++G(d,p) and MP2/6‐311++G(d,p) levels to explicitly identify all distinguishable molecular structures, and thereby the complete interconversion routes were carefully explored. Additional quantum calculations were carried out by G4 and CCSD(T)/6‐311++G(d,p) methods to acquire high‐level single point energies. With respect to quantum results, conformational analysis was conducted to study determinations, thermodynamic stabilities, and relative energies of distinct conformers. Temperature‐dependent populations of local minima for each dimethylcyclohexane were computed by Boltzmann distribution within 300–2500 K. Moreover, their unique inversion and topomerization processes were fully investigated, and potential energy surfaces were illustrated with the rigorous descriptions in two or three‐dimensional schemes for clarify.

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Impact of branched structures on cycloalkane ignition in a motored engine: Detailed product and conformational analyses

Cited by 30 publications

References 33 publications

Effects of methyl substitution on the auto-ignition of C16 alkanes

Effects of methyl substitution on the auto-ignition of C16 alkanes

Advances in rapid compression machine studies of low- and intermediate-temperature autoignition phenomena

Computational study of inversion‐topomerization pathways in 1,3‐dimethylcyclohexane and 1,4‐dimethylcyclohexane: Ab initio conformational analysis

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