Article
Thermodynamics
Marco Lubrano Lavadera, Matteo Pelucchi, Alexander A. Konnov
Summary: Blending ammonia with methylcyclohexane and toluene results in a non-proportional decrease in laminar burning velocity, with a slightly larger impact on toluene. A detailed kinetic model accurately predicts the experimental measurements after minor modifications to the chemistry and shows good agreement with the effect of equivalence ratio and ammonia fraction ranges investigated.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Xinlu Han, Marco Lubrano Lavadera, Christian Brackmann, Zhihua Wang, Yong He, Alexander A. Konnov
Summary: The formation of nitric oxide (NO) in methane (CH4) flames has been extensively studied, but discrepancies between simulations using different kinetic mechanisms and experimental results persist. Experimental data was collected for NO formation in post-flame zones of CH4+O2+N2 flames with varying oxygen ratios. Analysis showed that thermal-NO production plays a key role in the increase of NO mole fraction in stoichiometric and fuel-lean flames as oxygen ratio increases.
COMBUSTION AND FLAME
(2021)
Article
Energy & Fuels
Runfan Zhu, Xinlu Han, Ziyue Zhang, Yong He, Zhihua Wang
Summary: This study investigates the laminar burning velocities of NH3/CH4/H2S/air flames and explores the effect of H2S addition on flame propagation. The experimental results show that H2S addition decreases the flame speed, and the kinetic analysis reveals that the elevated H2S content significantly impacts the radicals pool in the flame. Reactions involving S-containing species become important for flame speed determination under high H2S content.
Article
Thermodynamics
Qianjin Lin, Xianzhong Hu, Jundie Chen, Alexander A. Konnov
Summary: In this study, laminar burning velocities of MIPK + air flames were measured, and it was found that existing kinetic models for MIPK combustion deviate from the measured data. The MIPK model was updated and a new di-methyl ketene sub-model was integrated, improving predictions of burning velocities and ignition delay times. Underestimation of the rate constants of the MIPK decomposition reaction in the previous model was identified, leading to underestimation of the measured burning velocities and significant overprediction of the ignition delay times.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Xinlu Han, Zhihua Wang, Yong He, Yanqun Zhu, Alexander A. Konnov
Summary: This study investigated the laminar burning velocities of CH4 + H2S + air flames and highlighted the importance of interactions between C and S-containing species, proposing solutions for handling hydrogen sulfide.
COMBUSTION AND FLAME
(2022)
Article
Energy & Fuels
Marco Lubrano Lavadera, Christian Brackmann, Gianluca Capriolo, Torsten Methling, Alexander A. Konnov
Summary: Experimental results on the adiabatic laminar burning velocities and post-flame NO mole fractions of neat and blended ethanol and n-heptane premixed flames demonstrate that the addition of ethanol increases the burning velocity and reduces NO formation. These findings are crucial for the development and optimization of chemical kinetic models.
Article
Thermodynamics
Marco Lubrano Lavadera, Jundie Chen, Alexander A. Konnov
Summary: This study experimentally determined the adiabatic laminar burning velocities for pyrrole/air flames and conducted a comparison between experimental and computational results. The model performance was improved by modifying a reaction rate constant, and the discrepancies among different models were observed.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
M. B. Raida, G. J. Hoetmer, A. . A. . Konnov, J. A. van Oijen, L. P. H. de Goey
Summary: A new setup for burning velocity measurements using the Heat Flux method has been constructed, with improved burner design. The experimental results have high accuracy and good agreement with literature data.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Donald R. Burgess, Robert R. Burrell, Valeri Babushok, Jeffrey A. Manion, Michael J. Hegetschweiler, Gregory T. Linteris
Summary: This work characterizes the flammability of refrigerant R-32 through experimental measurements and modeling, showing that burning velocities are controlled by key reactions and can be adjusted in the kinetic model to fit experimental data. The study found systematic uncertainties in measurements and differences between adiabatic and optically-thin limits, with burning velocities transitioning between these limits depending on various conditions. The validated detailed model accurately predicts burning velocities for R-32 mixtures under different conditions, providing a reliable basis for extrapolation.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Xinlu Han, Marco Lubrano Lavadera, Alexander A. Konnov
Summary: In this study, the laminar burning velocities of NH3+N2O+air flames were measured experimentally, showing a linear relationship with the fraction of nitrous oxide in the oxidizer mixture. Comparison with recent NH3 mechanisms revealed that the models of Nakamura et al. and Stagni et al. performed the best. The authors' H/N/O kinetic mechanism was updated and showed improved agreement with experimental data and literature.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Chenlin Chen, Zhihua Wang, Zuochao Yu, Xinlu Han, Yong He, Yanqun Zhu, Alexander A. Konnov
Summary: This study investigates the potential flame enhancement method in plasma-assisted combustion using ozone as an additive. The results show that ozone addition significantly affects the burning velocity of premixed ammonia gases, especially under fuel-rich conditions. The effects of ozone addition on the laminar burning velocity were experimentally and numerically investigated under various equivalence ratios.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Zhihua Wang, Xinlu Han, Yong He, Runfan Zhu, Yanqun Zhu, Zhijun Zhou, Kefa Cen
Summary: The laminar burning velocities of ammonia blended with methanol/air and ethanol/air flames were studied, a new kinetic mechanism was proposed and validated, and it was found that interactions between C- and N-containing species are insignificant for the laminar burning velocities of various ammonia blending mixtures.
COMBUSTION AND FLAME
(2021)
Article
Thermodynamics
Jundie Chen, Marco Lubrano Lavadera, Alexander A. Konnov
Summary: In this study, new measurements of the laminar burning velocity of ammonia + oxygen + argon mixtures were performed and validated against nine kinetic models. It was found that the models by Han et al., Shrestha et al., and Okafor et al. provided the best predictions. The model of Han et al. was modified to better reproduce the experimental data.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Shixing Wang, Zhihua Wang, Chenlin Chen, Ayman M. Elbaz, Zhiwei Sun, William L. Roberts
Summary: This study focuses on the combustion of NH3 blended fuels under elevated pressure conditions and proposes a new kinetic mechanism (CEU-NH3-Mech-1.1) based on experimental results. The new mechanism shows good predictability for laminar flame speed, ignition delay time, and species concentration in ammonia oxidation at high temperatures. Additionally, the study reveals the variation of pressure exponent with ammonia content and its role in validating kinetic mechanisms.
COMBUSTION AND FLAME
(2022)
Article
Energy & Fuels
Ziyue Zhang, Runfan Zhu, Yanqun Zhu, Wubin Weng, Yong He, Zhihua Wang
Summary: In 2020, energy-related CO2 emissions reached a record high of 31.5 Gt, resulting in an unprecedented atmospheric CO2 level of 412.5 ppm. Hydrogen blending in natural gas is a solution for maximizing clean energy utilization and enabling long-distance H-2 transport. However, there is still insufficient understanding of the combustion characteristics of natural gas blended with a high proportion of hydrogen, especially with minority species. Experimental and simulated results indicate that there is no difference between CH4 and NG with a large proportion of H-2 in terms of laminar burning velocity and kinetic analysis.
Article
Thermodynamics
Nitin Lokachari, Goutham Kukkadapu, Hwasup Song, Guillaume Vanhove, Maxence Lailliau, Guillaume Dayma, Zeynep Serinyel, Kuiwen Zhang, Roland Dauphin, Brian Etz, Seonah Kim, Mathias Steglich, Andras Bodi, Gina Fioroni, Patrick Hemberger, Sergey S. Matveev, Alexander A. Konnov, Philippe Dagaut, Scott W. Wagnon, William J. Pitz, Henry J. Curran
Summary: This study aims to develop and validate a detailed kinetic model for di-isobutylene to capture more new experimental data. Part 1 focuses on the low-to intermediate temperature kinetics of di-isobutylene. Measurements of ignition delay times and species identified during the oxidation process were performed to evaluate the most sensitive reactions controlling the ignition delay times of the DIB isomers under the pressure and temperature conditions necessary for autoignition in engines.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Jingwu Sun, Yuxiang Zhu, Jin-Tao Chen, Alexander A. Konnov, Ting Li, Lijun Yang, Chong-Wen Zhou
Summary: In this study, the reaction system of acrolein + H O2 was theoretically studied, and a detailed chemical kinetic sub-mechanism was developed to describe the combustion reactions of acrolein. The updated model was validated against experimental data to accurately predict the ignition delay times, burning velocity, and species profiles of acrolein.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Chenlin Chen, Zhihua Wang, Zuochao Yu, Xinlu Han, Yong He, Yanqun Zhu, Alexander A. Konnov
Summary: This study investigates the potential flame enhancement method in plasma-assisted combustion using ozone as an additive. The results show that ozone addition significantly affects the burning velocity of premixed ammonia gases, especially under fuel-rich conditions. The effects of ozone addition on the laminar burning velocity were experimentally and numerically investigated under various equivalence ratios.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Nitin Lokachari, Goutham Kukkadapu, Brian D. Etz, Gina M. Fioroni, Seonah Kim, Mathias Steglich, Andras Bodi, Patrick Hemberger, Sergey S. Matveev, Anna Thomas, Hwasup Song, Guillaume Vanhove, Kuiwen Zhang, Guillaume Dayma, Maxence Lailliau, Zeynep Serinyel, Alexander A. Konnov, Philippe Dagaut, William J. Pitz, Henry J. Curran
Summary: A wide range of high temperature experimental data was obtained to complement the oxidation data of the two di-isobutylene isomers presented in Part I, providing a basis for validating the developed kinetic model. Utilizing a pyrolysis microflow reactor, radical intermediates and stable products were detected for the di-isobutylene isomers in high dilution. Additional speciation data under oxidative conditions were recorded using a plug flow reactor, and combustion products were analyzed using GC and MS. Ignition delay time measurements, laminar burning velocities, and electronic structure calculations were also performed, and the predictions of the present mechanism were found to be in good agreement with the experimental measurements.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
A. S. Savchenkova, A. S. Semenikhin, I. V. Chechet, S. G. Matveev, A. A. Konnov, A. M. Mebel
Summary: Researchers have mainly focused on the formation of ortho-pyridyl in the pyridine structure, while the formation of meta- and para-pyridyls has received less attention. The rate constants of three pyridyl radicals formed from pyridine by hydrogen atom abstraction have been compared. The geometry of the reactants was optimized using density functional theory, followed by refinement of single-point energies using the ab initio G3(MP2,CC) hybrid method. The calculations indicate that the formation of ortho-pyridyl is more favorable, but all three radicals should be considered for a detailed description of coal combustion.
COMBUSTION EXPLOSION AND SHOCK WAVES
(2023)
Article
Energy & Fuels
Xinlu Han, Zhihua Wang, Riyi Lin, Alexander A. Konnov
Summary: This study investigates the phenomenon of SAFT in the CH4 + O2 + N2 and NH3 + O2 + N2 flames and examines the relationship between SAFT and laminar burning velocities. Experimental measurements and simulations reveal different SAFT regimes for CH4 and NH3 flames, and demonstrate the connection between SAFT extent and laminar burning velocity.
Article
Optics
Maria Ruchkina, Meena Raveesh, Armand Dominguez, Joakim Bood, Christian Brackmann
Summary: A method based on femtosecond two-photon excitation has been developed for simultaneous visualization of interference-free fluorescence of H and O atoms in turbulent flames. This work shows pioneering results on single-shot simultaneous imaging of these radicals under non-stationary flame conditions. The fluorescence signal, showing the distribution of H and O radicals in premixed CH4/O2 flames was investigated for equivalence ratios ranging from 0 = 0.8 to 0 = 1.3. The images have been quantified through calibration measurements and indicate single-shot detection limits on the order of a few percent. Experimental profiles have also been compared with profiles from flame simulations, showing similar trends.
Article
Thermodynamics
Alexander A. Konnov
Summary: The present study aims to model the chemiluminescence signature of NH3 + H2 + air flames. The author extended the detailed kinetic mechanism by incorporating reactions describing the formation and consumption of excited NO2*, NO(A), NH*, and NH2* based on previous analyses. The model was compared with experimental data, showing good agreement for NO(A), OH*, and NH*.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Jundie Chen, Marco Lubrano Lavadera, Alexander A. Konnov
Summary: In this study, new measurements of the laminar burning velocity of ammonia + oxygen + argon mixtures were performed and validated against nine kinetic models. It was found that the models by Han et al., Shrestha et al., and Okafor et al. provided the best predictions. The model of Han et al. was modified to better reproduce the experimental data.
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Alexander A. Konnov
Summary: The extended kinetic mechanism for NH3 + CH4 + air flames includes various excited species and is compared with experimental data. While the overall agreement between measurements and calculations is not as good as in NH3 + H2 + air flames, the predicted trends and chemiluminescence intensities of certain excited species are qualitatively in agreement with the measurements. The most important inconsistency is found for NO(A), suggesting potential inaccuracies in the formation of N2(A) precursors or incomplete reactive quenching of N2(A).
COMBUSTION AND FLAME
(2023)
Article
Thermodynamics
Alexander A. Konnov, Jundie Chen, Marco Lubrano Lavadera
Summary: This study reviews the laminar burning velocity of small alkyl esters and presents new data for methyl propionate + air flames. It compares the burning velocity of different esters and assesses structure-reactivity trends. Furthermore, it expands the authors' detailed kinetic mechanism and discusses the reactions controlling flame propagation.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Mohammad Shahsavari, Alexander A. Konnov, Xue-Song Bai, Agustin Valera-Medina, Tie Li, Mehdi Jangi
Summary: This study investigates the synergistic effects of nanosecond plasma discharge and hydrogen on the combustion characteristics of ammonia/air. The results show that increasing the plasma contribution decreases NOX emissions by up to 27% compared to flames assisted by hydrogen. Plasma reduces the strain rate sensitivity of reactant consumption, and discharging plasma with a pulse energy density of 9 mJ/cm3 alongside using 12% hydrogen by volume increases the flame speed of ammonia/air to that of conventional fossil fuels. Furthermore, the simultaneous utilization of high-energy plasma and hydrogen reduces NOX emissions by activating the DeNOX mechanisms.
Article
Optics
Maria Ruchkina, Meena Raveesh, Armand Dominguez, Joakim Bood, Christian Rackmann
Summary: A method based on femtosecond two-photon excitation has been developed for simultaneous visualization of interference-free fluorescence of H and O atoms in turbulent flames. This work shows pioneering results on single-shot simultaneous imaging of these radicals under non-stationary flame conditions. The fluorescence signal, showing the distribution of H and O radicals in premixed CH4/O2 flames was investigated for equivalence ratios ranging from 0 = 0.8 to 0 = 1.3. The images have been quantified through calibration measurements and indicate single-shot detection limits on the order of a few percent. Experimental profiles have also been compared with profiles from flame simulations, showing similar trends.
Article
Thermodynamics
Qianjin Lin, Xianzhong Hu, Jundie Chen, Alexander A. Konnov
Summary: In this study, laminar burning velocities of MIPK + air flames were measured, and it was found that existing kinetic models for MIPK combustion deviate from the measured data. The MIPK model was updated and a new di-methyl ketene sub-model was integrated, improving predictions of burning velocities and ignition delay times. Underestimation of the rate constants of the MIPK decomposition reaction in the previous model was identified, leading to underestimation of the measured burning velocities and significant overprediction of the ignition delay times.
COMBUSTION AND FLAME
(2023)
