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An experimental and modeling study of n-hexadecane autoignition under low-to-intermediate temperatures

Science China(Technological Sciences) 2020年第5期63卷 719-730页

作者： YU Liang WANG WenYu WANG SiXu FENG Yuan QIAN Yong LU XingCai Key Laboratory for Power Machinery and Engineering of M.O.E. Shanghai Jiao Tong UniversityShanghai 200240China

N-hexadecane is a potential candidate of diesel surrogate fuels and is also the largest linear alkane(n-alkanes)with known chemical kinetic *** objective of this study is to investigate the autoignition characteristics of n-hexadecane in the lowto-intermediate temperature region and to validate the existing kinetic *** this study,the ignition delay times(IDTs)of nhexadecane were measured using a heated rapid compression machine(RCM)at two pressures of 7 and 10 bar,and over equivalence ratios ranging from 0.5 to ***-stage ignition characteristic and the negative temperature coefficient(NTC)behavior of total ignition delay time were experimentally *** study paid special attention to the influence of pressure,equivalence ratio,and oxygen content on the IDTs of *** is observed that both the total IDTs and the first-stage IDTs decrease with the rise of those *** is worth noting that the first-stage IDT is found to show a greater dependence on temperature but a weaker dependence on other parameters compared to the total *** observed IDT dependence in the lowtemperature region(LTR)were quantitatively described by ignition delay time *** newly measured IDTs were then validated against two kinetic models(LLNL and CRECK).Simulation results show that both models underpredict the first-stage IDT but generally capture the temperature *** CRECK model well predicts the total IDTs of n-hexadecane while the LLNL model significantly underpredicts the total IDTs at most investigated *** the best of our knowledge,this study is the first investigation on n-hexadecane autoignition under low-to-intermediate temperatures,which deepens the understanding of large n-alkane oxidation and contributes to the improvement of the existing kinetic models.

关键词： n-hexadecane autoignition rapid compression machine low-temperature reactivity ignition delay time kinetic model

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Characteristic time scale as optimal input in Machine Learning algorithms:Homogeneous autoignition

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Energy and AI 2023年第4期14卷 238-252页

作者： Mohammed I.Radaideh Stelios Rigopoulos Dimitris A.Goussis Department of Mechanical Engineering Khalifa University of Science and TechnologyAbu Dhabi 127788United Arab Emirates Imperial College London Mechanical Engineering South Kensington Campus London SW72AZUnited Kingdom Research and Innovation Center on CO_(2)and H_(2) Khalifa University of Science and TechnologyAbu Dhabip127788United Arab Emirates

Considering temporally evolving processes,the search for optimal input selection in Machine Learning(ML)algorithms is extended here beyond(i)the readily available independent variables defining the process and(ii)the dependent variables suggested by feature extraction methods,by considering the time scale that characterizes the *** analysis is based on the process of homogeneous autoignition,which is fully determined by the initial temperature T(0)and pressure p(0)of the mixture and the equivalence ratio𝜙that specifies the initial mixture *** aim is to seek the optimal input for the prediction of the time at which the mixture *** Multilayer Perceptron(MLP)and Principal Component Analysis(PCA)algorithms are employed for prediction and feature extraction,*** is demonstrated that the time scale that characterizes the initiation of the process𝜐𝑓(0),provides much better accuracy as input to MLP than any pair of the three independent parameters T(0),p(0)and𝜙or their two principal ***,it is shown that using𝜐𝑓(0)as input results in a coefficient of determination R 2 in the range of 0.953 to 0.982,while the maximum value of R 2 when using the independent parameters or principal components is *** physical grounds,on which the success of𝜐𝑓(0)is based,are *** results suggest the need for further research in order to develop selection methodologies of optimal inputs among those that characterize the process.

关键词： Machine Learning Feature selection autoignition

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Measuring the Adiabatic Ignition Delay of n-Pentane Mixture using Rapid Compression Machine

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Journal of Thermal Science 2022年第2期31卷 552-560页

作者： J.A.Piehl O.Samimi-Abianeh Mechanical Engineering Department of Wayne State University DetroitMIUnited States of America

Recent combustion research has focused on low temperature combustion to meet engine emission regulations and to advance the development of low temperature homogenous compression ignition *** studies in this temperature regime are primarily performed by Rapid Compression Machines(RCMs)which are sensitive to the heat transfer characteristics of the experimental *** are widely used to measure autoignition data such as ignition delay and species *** ignition delays from RCMs are typically reported at an adiabatic condition;however,this assumption may produce a systematic error in ignition delay measurement as heat transfer is observed to reduce the pressure and temperature during the autoignition process,e.g.,a longer ignition delay has a greater pressure and temperature *** are custom built and have unique design characteristics that affect the heat transfer during the autoignition *** addition,depending on the diluent composition(e.g.,helium versus nitrogen or argon),different heat transfer characteristics are *** a result,autoignition results at similar conditions may vary from facility to facility or depending on the used *** dependency of the measured data on the used facility or diluent may produce uncertainty in the data which impact the development of high-fidelity combustion *** this work,a new method is developed and utilized to eliminate heat transfer from the ignition delay *** evaluate the new method,the autoignition of n-pentane mixtures in the low temperature regime were investigated using an *** vary the heat transfer,the compression ratio of the RCM was changed and the ignition delays were measured at similar pressure and temperature *** tests were performed at an equivalence ratio of approximately one and nitrogen and argon as *** applying the new method,the effect of heat transfer on the ignition delays were eliminated successfully and ignitio

关键词： heat transfer Rapid Compression Machine(RCM) n-pentane autoignition ignition delay

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Numerical study of methane/air jet flame in vitiated co-flow using tabulated detailed chemistry

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Science China(Technological Sciences) 2014年第9期57卷 1750-1760页

作者： HAN Chao ZHANG Pei YE TaoHong CHEN YiLiang Department of Thermal Science and Energy Engineering University of Science and Technology of China

Two different combustion models,the autoignition(AI)model and flamelet/progress variable(FPV)model,have been applied to study the auto-ignition process of methane/air jet flame in vitiated co-flow.A priori study was conducted to test the validity of the two *** show that the different range of predicted reaction rates is mainly responsible for their different performances in large eddy simulation(LES)*** this paper,beta PDF was used to model the mixture fraction distribution,while two different shapes of PDF,delta function and beta function,were applied for the reaction *** to the FPV model,the AI model combined with beta function for reaction progress could capture the auto-ignition process and predict the exact lifted *** the results indicate that the variance of reaction progress plays an important role in predicting the flame lifted height.

关键词： large eddy simulation flamelet/progress variables autoignition vitiated co-flow flame

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Effects of CO_2 Dilution on Methane Ignition in Moderate or Intense Low-oxygen Dilution(MILD) Combustion:A Numerical Study

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Chinese Journal of Chemical Engineering 2012年第4期20卷 701-709页

作者：曹甄俊朱彤 College of Mechanical Engineering Tongji University Shanghai DFYH Tech Services Co. Ltd.

Homogeneous mixtures of CH4/air under moderate or intense low-oxygen dilution（MILD） combustion conditions were numerically studied to clarify the fundamental effects of exhaust gas recirculation（EGR）,espe-cially CO2 in EGR gases,on ignition ***,effects of CO2 addition on autoignition delay time were emphasized at temperature between 1200 K and 1600 K for a wide range of the lean-to-rich equivalence ratio（0.2~2）.The results showed that the ignition delay time increased with equivalence ratio or CO2 dilution ***-thermore,ignition delay time was seen to be exponentially related with the reciprocal of initial *** concern was given to the chemical effects of CO2 on the ignition delay *** enhancement of ignition delay time with CO2 addition can be mainly ascribed to the decrease of H,O and OH *** predictions of tem-perature profiles and mole fractions of CO and CO2 were strongly related to the chemical effects of CO2.A single ignition time correlation was obtained in form of Arrhenius-type for the entire range of conditions as a function of temperature,CH4 mole fraction and O2 mole *** correlation could successfully capture the complex be-haviors of ignition of CH4/air/CO2 *** results can be applied to MILD combustion as ＂reference time＂,for example,to predict ignition delay time in turbulent reacting flow.

关键词： moderate or intense low-oxygen dilution combustion ignition delay time autoignition methane

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Stabilization mechanisms of lifted flames in a supersonic stepped-wall jet combustor

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2021年第4期22卷 314-330页

作者： Jin-cheng ZHANG Ming-bo SUN Zhen-guo WANG Hong-bo WANG Chao-yang LIU Science and Technology on Scramjet Laboratory National University of Defense TechnologyChangsha 410073China

Flame stabilization is the key to extending scramjets to hypersonic speeds;accordingly,this topic has attracted much attention in theoretical research and engineering *** study performed large eddy simulations(LESs)of lifted hydrogen jet combustion in a stepped-wall combustor,focusing on the flame stabilization mechanisms,especially for the autoignition *** assumed probability density function(PDF)approach was used to close the subgrid chemical reaction *** reliability of the solver was confirmed by comparing the LES results with experimental data and published simulated *** hydrogen jet and the incoming stream were first mixed by entraining large-scale vortices in the shear layer,and stable combustion in the near-wall region was achieved downstream of the flame induction *** autoignition cascade is a transition of fuel-rich flame to stoichiometric ratio flame that plays a role in forming the flame base,which subsequently causes downstream flame *** cases with different jet total temperatures are compared,and the results show that the increase in the total temperature reduces the lift-off distance of the *** the highest total temperature case,an excessively large scalar dissipation rate inhibits the autoignition cascade,resulting in a fuel-rich low-temperature flame.

关键词： Large eddy simulation(LES) autoignition Lifted flame Flame stabilization Assumed probability density function(PDF)

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Evaporation and Ignition of the Leaked Fuel by A Hot Plate

Evaporation and Ignition of the Leaked Fuel by A Hot Plate

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2002年安全与科学技术国际会议

作者： LI Yuanlong & LU Shouxiang (The State Key Laboratory of Fire Science University of Science&Technology of China Hefei 230026 China)

＜正＞ The evaporation and spontaneous ignition of a liquid fuel leaked on the hot plate has been studied experimentally and numerically. The leaked fuel evaporates on the hot plate and the yielding fuel vapor moves into the oxygen-containing atmosphere, and autoignites somewhere above the plate. The model describing the movement and reaction of the fuel vapor has been made and solved. The results showed some prospective autoignition area of the vapor. The maximum of the reaction rate was chosen as the ignition indicator. So the concluded autoignition place is very close to the experimental result.

关键词： hot plate leakage autoignition

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