An experimental and modeling study on auto-ignition kinetics of ammonia/methanol mixtures at intermediate temperature and high pressure

Li, Mengdi; He, Xiaoyu; Hashemi, Hamid; Glarborg, Peter; Lowe, Vincent M.; Marshall, Paul; Fernandes, Ravi X.; Shu, Bo

doi:10.1016/j.combustflame.2022.112160

Cited by 42 publications

(44 citation statements)

References 51 publications

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“…Temperature dependence of the high-pressure limiting rate coefficients for the NH 2 + CH 3 OH → products reaction. The rate coefficients are also compared with NH 2 + CH 3 OH (Li et al 19 ) and NH 2 + CH 4 (Siddique et al 21 ) reactions.…”

Section: F I G U R Ementioning

confidence: 99%

“…43 Based on the PES computed at the CCSD(T)/CBS//M06-2X/aug-cc-pVTZ level of theory, high-pressure limit rate coefficients, k ∞ (T), were computed using the conventional TST theory with explicit corrections of tunneling and HIRs. For various channels, Table 1 19 ) and CH 4 (Siddique et al 21 ). In addition, the results are compiled in Table S3 of SI for the temperature range of 300-2000 K. As seen in Figure 2, our calculated rate coefficients are faster by an average factor of 5 than those predicted by Li et al 19 Note that our barrier heights for both channels occurring via TS1 and TS2 are nearly identical to that reported by Li et al, 19 who also used CCSD(T) electronic structure calculations with aug-cc-pVTZ and aug-cc-pVQZ basis sets to obtain the extrapolated energies at the infinite basis set limit.…”

Section: F I G U R Ementioning

confidence: 99%

“…For various channels, Table 1 19 ) and CH 4 (Siddique et al 21 ). In addition, the results are compiled in Table S3 of SI for the temperature range of 300-2000 K. As seen in Figure 2, our calculated rate coefficients are faster by an average factor of 5 than those predicted by Li et al 19 Note that our barrier heights for both channels occurring via TS1 and TS2 are nearly identical to that reported by Li et al, 19 who also used CCSD(T) electronic structure calculations with aug-cc-pVTZ and aug-cc-pVQZ basis sets to obtain the extrapolated energies at the infinite basis set limit. Therefore, the discrepancy must have stemmed from the pre-exponential factor (see Figure 2).…”

Section: F I G U R Ementioning

confidence: 99%

“…There is a large number of studies rendered aiming to characterize the combustion behavior of ammonia-duel fuel systems. [6][7][8][9]12,13,18,19 As discussed above, NH 2 radicals reactions with fuels/intermediate species are crucial for combustion modeling. Surprisingly, there are limited kinetic data in the literature for the reactions of NH 2 radicals when compared to the isoelectronic OH and CH 3 radicals.…”

Section: Introductionmentioning

confidence: 99%

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A theoretical kinetic study of the reactions of NH₂ radicals with methanol and ethanol and their implications in kinetic modeling

Giri

Shrestha

V.‐T.

et al. 2022

Int J of Chemical Kinetics

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Amino (NH2) radicals play a central role in the pyrolysis and oxidation of ammonia. Several reports in the literature highlight the importance of the reactions of NH2 radicals with fuel in NH3‐dual‐fuel combustion. Therefore, we investigated the reactions of NH2 radicals with methanol (CH3OH) and ethanol (C2H5OH) theoretically. We explored the various reaction pathways by exploiting CCSD(T)/cc‐pV(T, Q)Z//M06‐2X/aug‐cc‐pVTZ level of theory. The reaction proceeds via complex formation at the entrance and exit channels in an overall exothermic process. We used canonical transition state theory to obtain the high‐pressure limiting rate coefficients for various channels over the temperature range of 300–2000 K. We discerned the role of various channels in the potential energy surface (PES) of NH2 + CH3OH/C2H5OH reactions. For both reactions, the hydrogen abstraction pathway at the OH‐site of alcohols plays a minor role in the entire T‐range investigated. By including the title reactions into an extensive kinetic model, we demonstrated that the reaction of NH2 radicals with alcohols plays a paramount role in accurately predicting the low‐temperature oxidation kinetics of NH3‐alcohols dual fuel systems (e.g., shortening the ignition delay time). On the contrary, these reactions have negligible importance for high‐temperature oxidation kinetics of NH3‐alcohol blends (e.g., not affecting the laminar flame speed). In addition, we calculated the rate coefficients for NH2 + CH4 = CH3 + NH3 reaction that are in excellent agreement with the experimental data.

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Section: F I G U R Ementioning

confidence: 99%

Section: F I G U R Ementioning

confidence: 99%

Section: F I G U R Ementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

A theoretical kinetic study of the reactions of NH₂ radicals with methanol and ethanol and their implications in kinetic modeling

Giri

Shrestha

V.‐T.

et al. 2022

Int J of Chemical Kinetics

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“…As a liquid hydrogen carrier, methanol (CH 3 OH) has been one of the most attractive renewable alternative fuels due to its acceptable price, wide-range source feedstock, and high LBV. − Thus, blending NH 3 with CH 3 OH as an additive is a promising choice for developing a carbon-neutral energy system. Li et al measured the ignition delay times of NH 3 /CH 3 OH/air mixtures at intermediate temperature and high pressure. The results showed that the NH 3 /CH 3 OH/air mixtures become more reactive with increasing CH 3 OH addition, and auto-ignition is promoted through different reaction pathways.…”

Section: Introductionmentioning

confidence: 99%

Explosion Characteristics of NH₃/CH₃OH/Air Mixtures

et al. 2022

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In this work, the explosive combustion of NH3/CH3OH/air mixtures covering wide ranges of equivalence ratios (0.7–1.7) and CH3OH mole fractions (0.2–1.0) was investigated experimentally and theoretically at ambient temperature and pressure. Results showed that the addition of CH3OH increases the maximum explosion pressure and maximum pressure rise rate. The empirical correlations for the maximum explosion pressure and maximum pressure rise rate are proposed, respectively. Furthermore, the heat loss of the explosion decreases significantly with the increasing CH3OH mole fraction. According to the instability analysis, the tendency of flame instability is enhanced with the enrichment of CH3OH due to the promoted hydrodynamic instability. Besides, the maximum pressure rise rate is augmented by flame instability. Kinetic analysis indicates that the CH3OH addition enhances the net heat release rate and active radicals. The total heat release of the NH3/CH3OH/air explosion is mainly attributed to the reactions R3: OH + H2 ⇔ H + H2O, R11: HO2 + H ⇔ 2OH, R24: CO + OH ⇔ CO2 + H, and R284: NH3 + H = NH2 + H2, while the predominant endothermal reaction is R1: H + O2 ⇔ O + OH. With the addition of CH3OH, the chemical effect has the largest contributions to the accelerated flame propagation on the lean and stoichiometric side, while the contributions of thermal and transport effects are dominant on the rich side.

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Laminar flame speed measurement and combustion mechanism optimization of methanol–air mixtures

Wang,

Zhang,

Zhong

2024

Int J of Chemical Kinetics

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Laminar flame speeds of methanol/air mixtures at 338–398 K are measured by the heat flux method, extending the range of equivalence ratio up to 2.1. And a new optimized methanol mechanism with 94 reactions is proposed by using the particle swarm algorithm, adjusting 20 Arrhenius pre‐exponential factors in their uncertainty domains. The optimized model is compared with eight methanol combustion mechanisms and experimental data published in recent years, covering a wide range of initial temperatures (298–1537 K), pressures (0.04–50 atm) and equivalence ratios (0.5–2.1). The results show that the optimized mechanism not only improves the accuracy of ignition delay time with rapid compression machine at low temperature but also moderately improve the description of laminar flame speed in lean and stoichiometric conditions. Meanwhile, the optimized model significantly enhances the prediction accuracy of CH3 and CH2O radical, and perfectly captures the evolution trend of HCO radical in laminar flat flame. Overall, the optimized mechanism provides the best overall description of the currently available measurements, leading to more accurate and comprehensive prediction of ignition delay time, laminar flame speed and species concentration.

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An experimental and modeling study on auto-ignition kinetics of ammonia/methanol mixtures at intermediate temperature and high pressure

Cited by 42 publications

References 51 publications

A theoretical kinetic study of the reactions of NH₂ radicals with methanol and ethanol and their implications in kinetic modeling

A theoretical kinetic study of the reactions of NH₂ radicals with methanol and ethanol and their implications in kinetic modeling

Explosion Characteristics of NH₃/CH₃OH/Air Mixtures

Laminar flame speed measurement and combustion mechanism optimization of methanol–air mixtures

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An experimental and modeling study on auto-ignition kinetics of ammonia/methanol mixtures at intermediate temperature and high pressure

Cited by 42 publications

References 51 publications

A theoretical kinetic study of the reactions of NH2 radicals with methanol and ethanol and their implications in kinetic modeling

A theoretical kinetic study of the reactions of NH2 radicals with methanol and ethanol and their implications in kinetic modeling

Explosion Characteristics of NH3/CH3OH/Air Mixtures

Laminar flame speed measurement and combustion mechanism optimization of methanol–air mixtures

Contact Info

Product

Resources

About

A theoretical kinetic study of the reactions of NH₂ radicals with methanol and ethanol and their implications in kinetic modeling

A theoretical kinetic study of the reactions of NH₂ radicals with methanol and ethanol and their implications in kinetic modeling

Explosion Characteristics of NH₃/CH₃OH/Air Mixtures