Article
Thermodynamics
Pavan Prakash Duvvuri, Hernando Maldonado Colman, Michael E. Mueller
Summary: The oxidation of soot is crucial for understanding its behavior in turbulent reacting flows. The kinetic rates of soot oxidation and the role of turbulent transport are both important factors in determining the evolution of soot. This study investigates the relative importance of small-scale turbulent transport and oxidation kinetics on predicting soot evolution in turbulent nonpremixed flames.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Chemistry, Physical
Jiseop Lee, Nam Il Kim
Summary: Adding hydrogen to methane can reduce CO2 emissions from combustion systems, but it also presents challenges. This study investigated the combustion characteristics of a turbulent fuel jet with coaxial air under elevated pressures. The results identified three clear flame stabilization modes, with the inner-lifted mode demonstrating the best combustion performance.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Thermodynamics
Abhijit Kalbhor, Jeroen van Oijen
Summary: This study numerically investigates the influence of flame curvature on soot formation in laminar non-premixed flames. The results reveal that the response of soot in curved flames is governed by the intricate coupling between flow convection, soot kinetics, and differential transport of soot. The dynamic response of soot formation to unsteady curvature and strain rate oscillations is also analyzed.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Agnes Jocher, Michael J. Evans, Paul R. Medwell, Bassam B. Dally, Heinz Pitsch, Graham J. Nathan
Summary: This study aims to evaluate the potential of the HMOM soot model in turbulent flames and identifies limitations in predicting soot behavior, suggesting areas for improvement in soot nucleation, condensation, and oxidation formulations.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Energy & Fuels
Liubin Hu, Hao Zhou
Summary: This study examines the influence of renewable energy biogas addition on methane self-excited thermoacoustic oscillation and pollutant NOx emission. It also explores the effects of swirl intensity and methane enrichment on biogas combustion. The results show that biogas addition effectively suppresses methane premixed self-excited oscillation swirling flames and promotes high-frequency self-excited oscillation and swirl stable combustion. Overall flame temperature and NOx emissions are reduced, indicating that biogas introduction effectively restrains thermoacoustic oscillation and limits NOx emissions. However, enriching biogas with more methane leads to better biogas/methane flame dynamics but higher NOx generation.
JOURNAL OF THE ENERGY INSTITUTE
(2023)
Article
Thermodynamics
Kanghwan Kim, Yong Jea Kim, A. J. Aspden, Dong-hyuk Shin
Summary: Direct numerical simulation was used to study the kinematics of ensemble-averaged flame position in harmonically oscillating turbulent premixed flames. The study investigated the effects of turbulence intensity, flame curvature, and distance from flame holder on turbulent flame speed and Markstein length. The results showed a strong linear correlation between turbulent flame speed and ensemble-averaged flame curvature, with the turbulent flame speed increasing with turbulence intensity. The turbulent Markstein length was found to be independent of turbulence intensity.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Zhang Chen, Tianwei Yang, Shanshan Zhang, Shan Li, Zhuyin Ren
Summary: This study systematically investigates the efficient modeling of NOx and CO formation characteristics, demonstrating the successful application in a full-scale methane gas turbine combustor. The results show that the predicted NOx and CO emissions agree with experimental measurements, with discrepancies in NOx emission attributed to fuel/air unmixedness and the sensitivity of CO emission prediction to combustion/kinetics model parameters.
Article
Thermodynamics
Yang Hua, Yejian Qian, Shun Meng
Summary: Bio-butanol mixed with gasoline is a potential decarbonization method in the transportation field. The addition of n-butanol to gasoline can decrease the formation of PAH and soot. The effects of n-butanol addition include the decrease of flame lift-off height, flame height, and OH/CH chemiluminescence intensity.
Article
Thermodynamics
Francisco Cepeda, Rodrigo Demarco, Felipe Escudero, Juan Jose Cruz Villanueva, Gonzalo Carvajal, Andres Fuentes
Summary: This study investigated the relationship between soot concentration and temperature, and provided new data for time-dependent numerical simulations by measuring local radiative heat flux on transient laminar flames. Results showed that forced condition significantly changed soot production, temperature distribution, and radiative properties, enhancing flame radiation.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Gulcan Ozel-Erol, Umair Ahmed, Nilanjan Chakraborty
Summary: The study investigated the distribution of flame topologies associated with flame self-interaction events in statistically spherical flames propagating into mono-sized droplet-laden mixtures. The analysis found that flame self-interaction events predominantly occur close to the burned gas side of the flame front, and are influenced by turbulence intensity and droplet diameter. Additionally, differences in the nature and distributions of flame self-interaction events between turbulent premixed flames and droplet cases may have implications for flame surface based modeling methodologies in simulating turbulent combustion in droplet-laden mixtures.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2021)
Article
Energy & Fuels
Tao Chen, Suyuan Yu, Yu Cheng Liu
Summary: The study investigates the effects of Soret diffusion on hydrogen-air edge flame propagation and diffusion-chemistry interaction through simulation. It demonstrates that Soret diffusion significantly influences the relationships between flame displacement speed and flame curvature, stretch rate, and scalar dissipation rate. Additionally, Soret diffusion weakens the chemical reaction component in edge flame propagation and affects the diffusion of hydrogen and hydrogen-2 in opposite ways.
Article
Thermodynamics
Shu Zheng, Yu Yang, Ran Sui, Qiang Lu
Summary: The numerical simulations in literature have not taken into account the effects of hydrocarbons like C2H4 and its combustion intermediate species C2H2 on thermal radiation, which may lead to errors in estimating the soot formation processes. Experimental results show that the radiation absorption and emission of C2H4 and C2H2 have an impact on the position of soot formation.
APPLIED THERMAL ENGINEERING
(2021)
Article
Engineering, Electrical & Electronic
Zhicong Li, Ludong Zhang, Chun Lou
Summary: The study introduces a new inversion algorithm for in-situ measurements of soot volume fraction (SVF) and temperature in axisymmetric soot-laden flames, showing that the TR-GSVD algorithm can provide more accurate results in investigating soot formation and oxidation mechanisms in combustion processes. Different types of flames are influenced by factors such as temperature, fuel flow, and oxidant flow, leading to varying effects on the combustion process of soot formation and oxidation.
IEEE TRANSACTIONS ON INSTRUMENTATION AND MEASUREMENT
(2021)
Article
Energy & Fuels
Wen Lu, Qian Mao, Feng-Ming Chu, Dan Yu, Jiu-Jie Kuang, Du Wang, Zhi-Hao Zheng, Zhen-Yu Tian
Summary: This study examines the relationship between temperature and soot formation in C2H2 laminar flames. The effects of flow rates and equivalence ratios on flame temperatures and structures were investigated. The length of the flame increased with higher equivalence ratios. The color of the flame changed from pale blue to bright green to bright yellow as the conditions shifted from fuel-lean to stoichiometric to ultra-rich. The formation mechanisms of soot particles were analyzed through sampling and observing the morphology of soot at different heights of the flame.
Article
Thermodynamics
Hope A. Michelsen, Emeric Boigne, Paul E. Schrader, K. Olof Johansson, Matthew F. Campbell, Ray P. Bambha, Matthias Ihme
Summary: We have developed a new method for extracting particulates and gas-phase species from flames by directing a small jet of inert gas through the flame to collect the sample. This approach allows for quenching and diluting the sample during extraction while minimizing the perturbations to the flame. Experimental results, TEM analysis, and numerical simulations demonstrate the significant advantages of this jet-entrainment sampling technique.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Hernando Maldonado Colman, Alberto Cuoci, Nasser Darabiha, Benoit Fiorina
Summary: Modeling soot formation is a challenging task, and the innovative virtual chemistry approach provides a new optimized global method for simulating turbulent sooting flames. This approach optimizes thermochemical parameters to describe combustion systems, trains thermochemical properties using genetic algorithms, reduces computational costs, and effectively predicts combustion system characteristics.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Alessandro Stagni, Steffen Schmitt, Matteo Pelucchi, Alessio Frassoldati, Katharina Kohse-Hoeinghaus, Tiziano Faravelli
Summary: This study experimentally investigated the oxidation behavior of DME in a flow reactor, considering both kinetics and fluid dynamics effects. The results showed that the standard PFR model had substantial deviations in predicting the reactivity and species profiles, especially for lean conditions at low flow rates and intermediate temperatures. The two-dimensional reactive flow model provided better agreement with the experimental data and improved the predictive modeling capability.
COMBUSTION AND FLAME
(2022)
Article
Thermodynamics
Sirio Brunialti, Xiaoyuan Zhang, Tiziano Faravelli, Alessio Frassoldati, S. Mani Sarathy
Summary: This work presents a methodology for automatically generating predictive lumped sub-mechanisms for normal and branched alkanes. Detailed sub-mechanisms for alkanes are generated using an updated version of the MAMOX ++ software, incorporating recent progress in low-temperature reaction classes and rate rules. The methodology proposes a new approach to generate lumped sub-mechanisms for fuel molecules by fitting stoichiometric parameters and reaction rates to match those in the detailed model. Validations show that the detailed models capture experimental targets well, while the lumped models perform similarly for normal alkanes but have slightly greater deviations for branched alkanes.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Songtao Guo, Alberto Cuoci, Yujie Wang, Liang Ji, C. Thomas Avedisian, Kalyanasundaram Seshadri, Dario Lopez-Pintor, John E. Dec, Nicholas DiReda, Alessio Frassoldati
Summary: An experimental and numerical study was conducted to investigate the combustion of a gasoline certification fuel and its surrogates in different combustion configurations. The study compared the performance of the surrogates and assessed the applicability of the kinetic mechanism and property database for simulations. The results showed that the S5 surrogate had a higher burning rate and good agreement was observed between the simulations and experimental measurements. The initial droplet diameter significantly influenced the droplet burning, with larger diameters resulting in decreased burning rates due to increased radiation losses.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Liang Ji, Alberto Cuoci, Alessio Frassoldati, Marco Mehl, Thomas Avedisian, Kalyanasundaram Seshadri
Summary: An experimental and computational investigation revealed the influence of iso-butanol on the critical conditions of autoignition of n-decane and n-heptane. The results showed that the addition of small amounts of iso-butanol strongly inhibited the low-temperature chemistry of n-decane and n-heptane, leading to an increase in the autoignition temperature.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Matteo Pelucchi, Steffen Schmitt, Nina Gaiser, Alberto Cuoci, Alessio Frassoldati, Hao Zhang, Alessandro Stagni, Patrick Osswald, Katharina Kohse-Hoeinghaus, Tiziano Faravelli
Summary: This study focuses on the interaction chemistry of DME-O2-NO mixtures in the low- to intermediate-temperature regime, investigating the oxidation behavior of DME in the presence of NO. The research combines experimental data with modeling analysis to study the kinetics of DME/NOx interactions, and assesses the uncertainty of key reactions using a polynomial chaos expansion analysis.
COMBUSTION AND FLAME
(2023)
Article
Chemistry, Physical
Vittoria Troisi, Veronica Piazza, Alessandro Stagni, Alessio Frassoldati, Gianpiero Groppi, Alessandra Beretta
Summary: Investigating bioethanol as a renewable energy source is crucial in the context of H2-based economy. A combined homo-heterogeneous kinetic scheme was developed and validated against experimental data to capture the relevant features of the bioethanol partial oxidation and steam reforming processes. The study developed a 36-species reduced homogeneous scheme and a macro-kinetic heterogeneous scheme with six molecular reactions to accurately describe the reacting systems.
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
(2023)
Article
Materials Science, Multidisciplinary
Francesco Serse, Zhaobin Ding, Mauro Bracconi, Matteo Maestrib, Andrea Nobili, Clarissa Giudici, Alessio Frassoldati, Tiziano Faravelli, Alberto Cuoci, Matteo Pelucchi
Summary: Thermal pyrolysis of hydrocarbons has potential for industrial production of hydrogen and valuable carbon materials. Predictive chemical kinetic models are essential for designing and scaling up pyrolysis reactors. This work proposes a methodology for determining rate constants of heterogeneous growth of pyrocarbon deposit using theory-based corrections of gas phase reactions. The methodology is applied to H-abstraction reactions, and a revised pyrocarbon deposition model is coupled to a state-of-the-art model describing gas phase dynamics and molecular growth of PAHs and soot. The comprehensive kinetic framework is validated with experimental data and can accurately simulate deposition rates and amount of deposited carbon under different operating conditions.
Article
Thermodynamics
Andrea Nobili, Dongsheng Zheng, Matteo Pelucchi, Alberto Cuoci, Alessio Frassoldati, Xin Hui, Tiziano Faravelli
Summary: This study investigates the effects of hydrogen and helium addition on soot formation in low strain rate counterflow diffusion flames. The results show that both hydrogen and helium addition can linearly decrease soot formation, with hydrogen having a larger effect due to its chemical properties. Increasing the oxygen concentration in the oxidizer stream also increases soot formation.
COMBUSTION AND FLAME
(2023)
Article
Energy & Fuels
Matteo Savarese, Alberto Cuoci, Ward De Paepe, Alessandro Parente
Summary: In this study, a novel methodology for the design of CRN models was proposed, which involves the post-processing of CFD data using unsupervised clustering and graph scanning algorithms. The methodology was tested on a semi-industrial furnace and showed promising predictive performances.
Article
Chemistry, Analytical
Elia Colleoni, Vasilios G. Samaras, Paolo Guida, Alessio Frassoldati, Tiziano Faravelli, William L. Roberts
Summary: Residual fuels, also known as 'bottom-of-the-barrel', are expected to play a crucial role in the transition towards renewable energy. Comprehensive two-dimensional gas chromatography (GCxGC) is used to characterize the volatile compounds released during the pyrolysis of these fuels. The study presents an algorithm for peak screening and post-processing, confirming its suitability for understanding the complex nature of the released mixtures. The methodology can be applied to other complex mixtures, such as bio-oils, plastics, and biomasses.
JOURNAL OF ANALYTICAL AND APPLIED PYROLYSIS
(2023)
Article
Thermodynamics
Yujie Wang, Alberto Cuoci, Songtao Guo, Liang Ji, C. Thomas Avedisian, Kalyanasundaram Seshadri, Alessio Frassoldati
Summary: This paper presents an experimental and numerical study on the combustion of isolated n-butyl acetate droplets in the standard atmosphere. Numerical simulations with a model incorporating unsteady gas and liquid transport, variable properties, and radiation were conducted. The influence of different kinetic mechanisms on burning was evaluated. The numerical predictions were validated by experimental measurements, and the effects of initial droplet diameter on the maximum gas temperature and peak mole fractions of CO2 and CO were examined.
PROCEEDINGS OF THE COMBUSTION INSTITUTE
(2023)
Article
Thermodynamics
Yifan Yang, Haodong Zhang, Linye Li, Mingming Gu, Xi Xia, Fei Qi
Summary: This paper investigates the formation of a blue whirl by controlling tangential and radial airflows. By using a unique fire whirl apparatus, the blue whirl can be formed directly upon ignition without going through the transient phase. The study also discovers new flame regimes and explores the mechanism behind the formation and transition of the blue whirl.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Xiaobin Qi, Songyan Gao, Zhiping Zhu, Qinggang Lyu, Haixia Zhang
Summary: This study experimentally investigated the propagation characteristics of reverse combustion under oxygen-limited and enriched conditions. The contribution of volatiles gas-phase oxidation and char surface oxidation to reverse combustion was evaluated. The results showed that oxygen enrichment expanded the operating range of oxygen flow rate for reverse combustion and enhanced the low-temperature oxidation of the solid fuel. The findings provide a better understanding of the driving mechanism of reverse combustion and have important implications for efficient thermal conversion of solid fuels.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Bingjie Chen, Peng Liu, Bingzhi Liu, Zhandong Wang, Xiang Gao, William L. Roberts
Summary: In this study, the low temperature oxidation of 1,2,4-trimethylbenzene was investigated using experiments and numerical simulations. The results showed the presence of toxic oxygenated aromatic compounds and proposed potential formation pathways. The numerical simulations accurately predicted the mole fractions of most compounds, but some compounds were missing.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Meng Sui, Zhiheng Zhu, Fashe Li, Hua Wang
Summary: The effect of adding ferrocene as a combustion catalyst to Jatropha biodiesel on its pyrolysis and combustion performance is investigated. The results show that adding ferrocene reduces activation energy and harmful emissions while improving combustion efficiency.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Manaf Sheyyab, Mohammed Abdulrahman, Subharaj Hossain, Patrick T. Lynch, Eric K. Mayhew, Kenneth Brezinsky
Summary: Fuel surrogates, simplified representations of complex fuels, accurately model speciation results and reaction kinetics, reproduce the ignition quality and chemical functional group compositions of their parent fuels.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Yan Wang, Shumeng Xie, Hannes Bottler, Yiqing Wang, Xinyi Chen, Arne Scholtissek, Christian Hasse, Zheng Chen
Summary: This study investigates how flow affects the ignition and transition process of a cool flame. The results show that the ignition energy determines the highest temperature and the strain rate influences the flame propagation and the transition from cool flame to hot flame.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Tanusree Chatterjee, Mengyuan Wang, Goutham Kukkadapu, Chih-Jen Sung, William J. Pitz
Summary: Cycloalkanes, including cyclohexane, are important hydrocarbons in transportation fuels. However, limited oxidation data at low-to-intermediate temperatures and inadequate predictive ability of kinetic models have hindered the understanding and improvement of cyclohexane oxidation. This study provides experimental and modeling results to develop a more accurate kinetic model for cyclohexane oxidation.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Tao Wu, Erik Hagen, Haiyang Wang, Dylan J. Kline, Michael R. Zachariah, Carole Rossi
Summary: It was found that incorporating CuO into Al/I2O5 can significantly reduce the ignition time and enhance the combustion performance. The optimum composition of 80/20 wt% of I2O5/CuO shows a 30 times shorter ignition time and produces a peak pressure and pressurization rate 4 and 26 times greater than traditional Al/I2O5. A series of characterizations helped unravel the cause of improvement and propose a reaction mechanism for this ternary Al/I2O5/CuO system. This study proposes a facile, inexpensive, and efficient way to enhance the combustion performance of Al/I2O5 biocidal nanoenergetic materials.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Mahmoud Gadalla, Shervin Karimkashi, Islam Kabil, Ossi Kaario, Tianfeng Lu, Ville Vuorinen
Summary: In this study, the flame initiation process in dual-fuel spray assisted combustion is explored through scale-resolved simulations, providing numerical evidence on the initiation of premixed flames. It is found that there is a transient mixed-mode combustion phase after ignition, followed by a primarily deflagrative combustion mode. The interactions between turbulence and premixed flame front are characterized in the corrugated regime.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Neeraj Kumar Pradhan, Arindrajit Chowdhury, Debasis Chakraborty, Neeraj Kumbhakarna
Summary: In this study, a modified model for predicting the burn rate of composite solid propellants is proposed. The model has been validated against experimental and theoretical results, and it outperforms existing models in all cases considered. The model is highly robust and provides results quickly, making it highly efficient in terms of time, effort, and computational resources.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Lili Ye, Zhihe Zhang, Fan Wang, Xiaodong Wang, Yiming Lu, Lei Zhang
Summary: This study investigated the pyrolysis mechanism of octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX) explosive using ab initio and kinetic modeling simulations. The results showed that N-NO2 bond fission and C-H beta-scission are important channels in the decomposition of HMX.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Andrei N. Lipatnikov, Hsuchew Lee, Peng Dai, Minping Wan, Vladimir A. Sabelnikov
Summary: This study investigates the importance of thermodiffusive and hydrodynamic instabilities of laminar flames in turbulent flows through numerical simulations. The analysis suggests that laminar flame instabilities play a minor role at sufficiently high Karlovitz numbers.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Shijie Xu, Yue Qiu, Leilei Xu, Jianqing Huang, Shen Li, Elna J. K. Nilsson, Zhongshan Li, Weiwei Cai, Marcus Alden, Xue-Song Bai
Summary: Metal powder is a promising carbon-free and recyclable energy carrier. In this study, a computational model for the combustion and phase change of micron-sized iron particles was proposed and validated. The model successfully captures the melting, surface reactions, cooling, and solidification processes. The study also reveals a two-stage solidification phenomenon and identifies a diffusion-controlled mechanism during the melting process. The reaction between iron and CH4/O2/N2 flame products is found to play a significant role in the iron combustion process.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Khalid Aljohani, Abd El-Sabor Mohamed, Haitao Lu, Henry J. Curran, S. Mani Sarathy, Aamir Farooq
Summary: This study investigates the impact of exhaust gas recirculation (EGR) and NOx on the ignition delay time of oxygenated gasoline. A gasoline surrogate model is developed and the experimental data are useful for predicting fuel ignition behavior in internal combustion engines. The results show that EGR inhibits gasoline reactivity, while NOx has a promoting effect at high temperatures. This research is important for understanding the combustion behavior of gasoline in engines.
COMBUSTION AND FLAME
(2024)
Article
Thermodynamics
Chengcheng Ao, Jia Yan, Tong Yan, Lidong Zhang, Pan Wang
Summary: This study investigates the inhibitory effect of ammonia blended with hydrocarbon fuels on soot formation. The results show that there is a chemical interaction between ammonia and polycyclic aromatic hydrocarbons (PAHs), blocking the formation of larger PAHs.
COMBUSTION AND FLAME
(2024)