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Zuohua Huang - One of the best experts on this subject based on the ideXlab platform.
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Shock Tube Measurements and Kinetic Investigation on the Ignition Delay Times of Methane/Dimethyl Ether Mixtures
Energy & Fuels, 2020Co-Authors: Chenglong Tang, Jiaxiang Zhang, Zuohua HuangAbstract:In this work, the Ignition Delay times of stoichiometric methane/dimethyl ether (DME) were measured behind the reflected shock waves over a wide range of conditions: temperatures between 1134 and 2105 K, pressures of 1, 5, and 10 bar, a DME blending ratio from 0 to 100% (M100 to M0), and an argon concentration of 95%. The present shock tube facility was validated by comparing the measured Ignition Delay times of DME with literature values and was used for measurement of the subsequent methane/DME Ignition Delay times. The Ignition Delay times of all mixtures exhibit a negative pressure dependence. For a given temperature, the Ignition Delay time of methane/DME decreases remarkably with the presence of only 1% DME. As the DME blending ratio increases, the Ignition Delay times are correspondingly decreased; however, the Ignition promotion effect of DME is decreased. The calculated Ignition Delay times of methane/DME mixtures using two recently developed kinetic mechanisms are compared with those of measurem...
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high temperature Ignition Delay time of dme n pentane mixture under fuel lean condition
Fuel, 2017Co-Authors: Xue Jiang, Feiyu Yang, Yingjia Zhang, Fuquan Deng, Zuohua HuangAbstract:Abstract Ignition Delay times were measured behind reflect shock waves for the lean DME/ n -pentane fuel blends with DME blending ratios from 0% to 100% over a wide range of conditions: pressures from 2 to 20 atm, temperatures from 1100 to 1600 K and equivalence ratio of 0.5. Correlations of Ignition Delay times of DME/ n -pentane were deduced from the experimental data using multiple linear regression. Comparison between measured Ignition Delay times and numerical predictions by five available kinetic mechanisms, namely NUI Galway pentane isomer model, JetSurF2.0 model, LLNL n -alkanes Model, NUI Galway Mech_56.54 Model and Wang’s DME model, were conducted. NUI Galway pentane isomer model shows good predictions for Ignition Delay times of DME, n -pentane and their blends which was conducted in this study to interpret the effect of DME addition on the Ignition chemistry of n -pentane.
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experimental and kinetic study on Ignition Delay times of dme h2 o2 ar mixtures
Combustion and Flame, 2014Co-Authors: Erjiang Hu, Jiaxiang Zhang, Zihang Zhang, Zuohua HuangAbstract:Abstract Ignition Delay times of dimethyl ether (DME)/hydrogen/oxygen/argon mixtures (hydrogen blending ratio ranging from 0% to 100%) were measured behind reflected shock waves at pressures of 1.2–10 atm, temperature range of 900–1700 K, and for the lean ( ϕ = 0.5), stoichiometric ( ϕ = 1.0) and rich ( ϕ = 2.0) mixtures. For more understanding the effect of initial parameters, correlations of Ignition Delay times for the lean mixtures were obtained on the basis of the measured data ( X H2 ⩽ 95%) through multiple linear regression. Ignition Delay times of the DME/H 2 mixtures demonstrate three Ignition regimes. For X H2 ⩽ 80%, the Ignition is dominated by the DME chemistry and Ignition Delay times show a typical Arrhenius dependence on temperature and pressure. For 80% ⩽ X H2 ⩽ 98%, the Ignition is dominated by the combined chemistries of DME and hydrogen, and Ignition Delay times at higher pressures give higher Ignition activation energy. However, for X H2 ⩾ 98%, the transition in activation energy for the mixture was found as decreasing the temperature, indicating that the Ignition is dominated by the hydrogen chemistry. Simulations were made using two available models and different results were presented. Thus, sensitivity analysis was performed to illustrate the causes of different simulation results of the two models. Subsequently, chemically interpreting on the effect of hydrogen blending ratio on Ignition Delay times was made using small radical mole fraction and reaction pathway analysis. Finally, high-pressure simulations were performed, serving as a starting point for the future work.
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Experimental and Kinetic Study on Ignition Delay Times of iso- Butanol
Energy & Fuels, 2014Co-Authors: Yingjia Zhang, Zemin Tian, Feiyu Yang, Zuohua HuangAbstract:Ignition Delay times of iso-butanol with fuel concentration of 0.5–1.0% were measured behind reflected shock waves. The experiments were conducted in the temperature range of 900–1700 K, at pressures of 1.2–10.0 atm and equivalence ratios of 0.5–2.0. The measured Ignition Delay times were compared with previous data under the same conditions and were correlated through multiple linear regression. Using the correlation, the Ignition Delay times of iso-butanol were compared to those of n-butanol. It was found that iso-butanol presented longer Ignition Delay time than that of n-butanol. Three available models were used to simulate the Ignition Delay times. Results showed that Sarathy model exhibited the best predictions at high temperature, but none of these models could well reproduce the measured Ignition Delay times at intermediate–low temperature. Reaction pathway analysis was performed to chemically interpret the observed difference in Ignition Delay times of n-butanol and iso-butanol. In addition, sens...
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further study on the Ignition Delay times of propane hydrogen oxygen argon mixtures effect of equivalence ratio
Combustion and Flame, 2013Co-Authors: Chenglong Tang, Zuohua HuangAbstract:Using a shock tube facility, measurements on Ignition Delay times of propane/hydrogen mixtures (hydrogen fraction XH2 is from 0% to 100%) were conducted at equivalence ratios of 0.5, 1.0 and 2.0. Results show that when XH2 is less than 70%, Ignition Delay time shows a strong Arrhenius temperature dependence, and the Ignition Delay time increases with the increase of equivalence ratio. When XH2 is larger than 95%, the Ignition Delay times do not retain an Arrhenius-like temperature dependence, and the effect of equivalence ratio is very weak when the hydrogen fraction is further increased. Numerical studies were made using two selected kinetic mechanisms and the results show that the predicted Ignition Delay times give a reasonable agreement with the measurements under all test conditions. Both measurements and predictions show that for mixtures with XH2 less than 70%, the Ignition Delay time is only moderately decreased with the increase of XH2, indicating that hydrogen addition has a weak effect on the Ignition enhancement. Sensitivity analysis reveals the key reactions that control the simulation of Ignition Delay time. Further investigation of the H-atom consumption is made to interpret the Ignition Delay time dependence on equivalence ratio and XH2.
Ronald K. Hanson - One of the best experts on this subject based on the ideXlab platform.
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Ignition Delay time correlations for distillate fuels
Fuel, 2017Co-Authors: David F Davidson, Jiankun Shao, Ronald K. HansonAbstract:Abstract Ignition Delay times were measured behind reflected shock waves in a shock tube for a wide variety of distillate fuels over a range of temperatures, pressures and mixtures. The fuels studied include: jet fuels (JP-5, JP-8, and Jet A), rocket propellants (RP-2), diesel fuels (F-76 and DF-2) and gasoline. A simple correlation was found to describe the Ignition Delay times for all these fuel/air experiments for equivalence ratios near unity, temperatures from 1000 to 1400 K, and pressures from 6 to 60 atm. A simple correlation was also found for low-fuel-concentration experiments diluted in argon. Previously published Ignition Delay time data were found to be in good agreement with these correlations. Finally, for several fuels studied, systematic variations were seen in the activation energy for Ignition Delay time measurements with varying equivalence ratio and oxygen concentration.
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Ignition Delay times of conventional and alternative fuels behind reflected shock waves
Proceedings of the Combustion Institute, 2015Co-Authors: Sijie Li, David F Davidson, Ronald K. HansonAbstract:Abstract The auto-Ignition characteristics of two distillate jet fuels and fifteen alternative fuels (including fuel blends) were investigated using shock-tube/laser-absorption methods. Ignition Delay times were measured behind reflected shock waves over a range of temperatures, 1047–1520 K, and equivalence ratios, 0.25–2.2, in two pressure and mixture regimes: for fuel/air mixtures at 2.07–8.27 atm, and for fuel/4%oxygen(O 2 )/argon(Ar) mixtures at 15.9–44.0 atm. In both pressure ranges, the Ignition Delay times of the alternative fuels and the blends with conventional fuels were found to be similar to those of conventional fuels but with some small systematic differences manifesting the different fuel types. In particular, for alternative aviation fuels, alcohol-to-jet fuels were found to be generally less reactive than Fischer–Tropsch paraffinic kerosenes or hydro-processed renewable jet fuels. Comparisons were also made of the Ignition Delay time data with detailed kinetic modeling for selected fuels. These comparisons show that existing multi-component surrogate/mechanism combinations can successfully predict the behavior of these fuels over the conditions studied. For those fuels lacking kinetic models, the current Ignition Delay time measurements provide useful target data for development and validation of relevant surrogate mixtures and reaction mechanisms.
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shock tube measurements of branched alkane Ignition Delay times
Fuel, 2014Co-Authors: Sijie Li, David F Davidson, Ashley Campos, Ronald K. HansonAbstract:Abstract Ignition Delay times for three branched alkanes: 2,4-dimethylpentane, 2,5-dimethylhexane and iso-octane, were measured behind reflected shock waves. The Ignition Delay time measurements cover the temperature range of 1313–1554 K, with pressures near 1.5 and 3 atm, equivalence ratios of 0.5 and 1 in 4% oxygen/argon. Regression analyses of the data over the limited range of conditions studied yield the following correlations for Ignition Delay time as a function of temperature (K), pressure (atm), and equivalence ratio: 2,4-DMP: τ ign [s] = 8.4 × 10 −11 P −0.61 Φ 1.03 exp(46.6[kcal/mol]/RT) 2,5-DMH: τ ign [s] = 2.1 × 10 −10 P −0.60 Φ 0.99 exp(43.4[kcal/mol]/RT) Iso-octane: τ ign [s] = 1.1 × 10 −10 P −0.47 Φ 0.86 exp(45.7[kcal/mol]/RT) Comparing the current Ignition Delay time data of branched alkanes with published values for their normal alkane isomers, it was confirmed that increasing the degree of carbon chain branching lowers the reactivity of the fuel and increases the Ignition Delay time. In addition, longer Ignition Delay times were observed for 2,4-dimethylpentane than 2,5-dimethylhexane, confirming the influence on reactivity by changing the straight carbon chain by one carbon for symmetric branched hydrocarbon fuels. The low reactivity and long Ignition Delay times for branched alkanes were attributed to the high concentrations of propene and iso-butene formed when branched alkanes decompose, as propene and iso-butene reduce the radical pool by consuming OH, O and H to form less-reactive species like allyl radical and allene. The Ignition Delay times of the fuels studied were also seen to increase monotonically with octane number under the current test conditions.
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Ignition Delay times of methyl oleate and methyl linoleate behind reflected shock waves
Proceedings of the Combustion Institute, 2013Co-Authors: M F Campbell, Ronald K. Hanson, David F Davidson, C K WestbrookAbstract:Abstract Ignition Delay times for methyl oleate (C 19 H 36 O 2 , CAS: 112-62-9) and methyl linoleate (C 19 H 34 O 2 , CAS: 112-63-0) were measured for the first time behind reflected shock waves, using an aerosol shock tube. The aerosol shock tube enabled study of these very-low-vapor-pressure fuels by introducing a spatially-uniform fuel aerosol/4% oxygen/argon mixture into the shock tube and employing the incident shock wave to produce complete fuel evaporation, diffusion, and mixing. Reflected shock conditions covered temperatures from 1100 to 1400 K, pressures of 3.5 and 7.0 atm, and equivalence ratios from 0.6 to 2.4. Ignition Delay times for both fuels were found to be similar over a wide range of conditions. The most notable trend in the observed Ignition Delay times was that the pressure and equivalence ratio scaling were a strong function of temperature, and exhibited cross-over temperatures at which there was no sensitivity to either parameter. Data were also compared to the biodiesel kinetic mechanism of Westbrook et al. (2011) [10] , which underpredicts Ignition Delay times by about 50%. Differences between experimental and computed Ignition Delay times were strongly related to existing errors and uncertainties in the thermochemistry of the large methyl ester species, and when these were corrected, the kinetic simulations agreed significantly better with the experimental measurements.
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shock tube measurements of Ignition Delay times for the butanol isomers
Combustion and Flame, 2012Co-Authors: Ivo Stranic, David F Davidson, Deanna P Chase, Joseph T Harmon, Sheng Yang, Ronald K. HansonAbstract:Abstract Ignition Delay times of the four isomers of butanol were measured behind reflected shock waves over a range of experimental conditions: 1050–1600 K, 1.5–43 atm, and equivalence ratios of 1.0 and 0.5 in mixtures containing 4% O2 diluted in argon. Additional data were also collected at 1.0–1.5 atm in order to replicate conditions used by previous researchers. Good agreement is seen with past work for 1-butanol Ignition Delay times, though our measured data for the other isomers were shorter than those found in some previous studies, especially at high temperatures. At most conditions, the Ignition Delay time increases for each isomer in the following order: 1-butanol, 2-butanol and i-butanol nearly equal, and t-butanol. In addition, t-butanol has a higher activation energy than the other three isomers. In a separate series of high-pressure experiments, Ignition Delay times of 1-butanol in stoichiometric air were measured at temperatures as low as 800 K. At temperatures below 1000 K, pre-Ignition pressure rises as well as significant rollover of Ignition Delay times were observed. Modeling of all collected data using several different chemical kinetic mechanisms shows partial agreement with the experimental data depending on the mechanism, isomer, and conditions. Only the mechanism developed by Vranckx et al. [1] partially explains the rollover and pre-Ignition observed in stoichiometric experiments in air.
Chenglong Tang - One of the best experts on this subject based on the ideXlab platform.
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Shock Tube Measurements and Kinetic Investigation on the Ignition Delay Times of Methane/Dimethyl Ether Mixtures
Energy & Fuels, 2020Co-Authors: Chenglong Tang, Jiaxiang Zhang, Zuohua HuangAbstract:In this work, the Ignition Delay times of stoichiometric methane/dimethyl ether (DME) were measured behind the reflected shock waves over a wide range of conditions: temperatures between 1134 and 2105 K, pressures of 1, 5, and 10 bar, a DME blending ratio from 0 to 100% (M100 to M0), and an argon concentration of 95%. The present shock tube facility was validated by comparing the measured Ignition Delay times of DME with literature values and was used for measurement of the subsequent methane/DME Ignition Delay times. The Ignition Delay times of all mixtures exhibit a negative pressure dependence. For a given temperature, the Ignition Delay time of methane/DME decreases remarkably with the presence of only 1% DME. As the DME blending ratio increases, the Ignition Delay times are correspondingly decreased; however, the Ignition promotion effect of DME is decreased. The calculated Ignition Delay times of methane/DME mixtures using two recently developed kinetic mechanisms are compared with those of measurem...
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further study on the Ignition Delay times of propane hydrogen oxygen argon mixtures effect of equivalence ratio
Combustion and Flame, 2013Co-Authors: Chenglong Tang, Zuohua HuangAbstract:Using a shock tube facility, measurements on Ignition Delay times of propane/hydrogen mixtures (hydrogen fraction XH2 is from 0% to 100%) were conducted at equivalence ratios of 0.5, 1.0 and 2.0. Results show that when XH2 is less than 70%, Ignition Delay time shows a strong Arrhenius temperature dependence, and the Ignition Delay time increases with the increase of equivalence ratio. When XH2 is larger than 95%, the Ignition Delay times do not retain an Arrhenius-like temperature dependence, and the effect of equivalence ratio is very weak when the hydrogen fraction is further increased. Numerical studies were made using two selected kinetic mechanisms and the results show that the predicted Ignition Delay times give a reasonable agreement with the measurements under all test conditions. Both measurements and predictions show that for mixtures with XH2 less than 70%, the Ignition Delay time is only moderately decreased with the increase of XH2, indicating that hydrogen addition has a weak effect on the Ignition enhancement. Sensitivity analysis reveals the key reactions that control the simulation of Ignition Delay time. Further investigation of the H-atom consumption is made to interpret the Ignition Delay time dependence on equivalence ratio and XH2.
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high temperature Ignition Delay times of c5 primary alcohols
Combustion and Flame, 2013Co-Authors: Chenglong Tang, Jiaxiang Zhang, Zuohua HuangAbstract:Abstract Ignition Delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-methyl-1-butanol) were measured behind reflected shock waves. Experiments were conducted in the temperature range of 1100–1500 K, pressures of 1.0 and 2.6 atm, equivalence ratios of 0.25, 0.5 and 1.0, and O2 concentration in the fuel/O2/Ar mixtures varying from 3.75% to 15%. Measurements show that the Ignition Delay time and the global activation energy of the three isomers both decrease in the order of iso-pentanol, 2-methyl-1-butanol, and n-pentanol. Chemical kinetic mechanisms for n-pentanol (Mech NP) and iso-pentanol (Mech IP), recently developed by Dagaut and co-workers, were used to model the respective Ignition Delay times. Results show that Mech NP yields close agreement at the equivalence ratio of 0.25, but the agreement is moderated with increasing equivalence ratio. Mech IP yields fairly close agreements at relatively higher temperatures but over-predicts the measurements by 50% at relatively lower temperatures for the three equivalence ratios studied. A new 2-methyl-1-butanol high temperature mechanism was proposed and validated against the Ignition Delay data. Sensitivity analysis for both n-pentanol and iso-pentanol showed the dominance of small radical reactions. Reaction pathway analysis aided further scrutiny of the fuel-specific reactions in Mech NP, leading to refinement of the kinetic model, and improved agreement between the predicted and measured Ignition Delay times as well as the jet-stirred reactor results.
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Measurements and kinetic study on Ignition Delay times of propane/hydrogen in argon diluted oxygen
International Journal of Hydrogen Energy, 2013Co-Authors: Chenglong Tang, Zuohua HuangAbstract:Abstract Measurements on Ignition Delay times of propane/hydrogen mixtures in argon diluted oxygen were conducted for hydrogen fractions in the fuel mixtures ( X H 2 ) from 0 to 100%, pressures of 1.2, 4.0 and 10 atm, and temperatures from 1000 to 1600 K using the shock-tube. Results show that for X H 2 less than 70%, Ignition Delay time shows a strong Arrhenius temperature dependence and it decreases with the increase of pressure, while for X H 2 larger than 90%, there is a crossover pressure dependence of the Ignition Delay time with increasing temperature. Numerical studies were made using the selected kinetic mechanisms and results show that the predicted Ignition Delay time gives a reasonable agreement with the measurements. Both measurements and predictions show that for X H 2 less than 70%, the Ignition Delay time is only moderately decreased with the increase of X H 2 , indicating that hydrogen addition has weak effect on Ignition enhancement. Sensitivity analysis reveals the key reactions that control the simulation of Ignition Delay time. Kinetic study is made to interpret the Ignition Delay time dependence on pressure and X H 2 .
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High temperature Ignition Delay times of C5 primary alcohols
Combustion and Flame, 2013Co-Authors: Chenglong Tang, Liangjie Wei, Xingjia Man, Jiaxiang Zhang, Zuohua Huang, Chung K. LawAbstract:Ignition Delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-methyl-1-butanol) were measured behind reflected shock waves. Experiments were conducted in the temperature range of 1100-1500K, pressures of 1.0 and 2.6atm, equivalence ratios of 0.25, 0.5 and 1.0, and O2concentration in the fuel/O2/Ar mixtures varying from 3.75% to 15%. Measurements show that the Ignition Delay time and the global activation energy of the three isomers both decrease in the order of iso-pentanol, 2-methyl-1-butanol, and n-pentanol. Chemical kinetic mechanisms for n-pentanol (Mech NP) and iso-pentanol (Mech IP), recently developed by Dagaut and co-workers, were used to model the respective Ignition Delay times. Results show that Mech NP yields close agreement at the equivalence ratio of 0.25, but the agreement is moderated with increasing equivalence ratio. Mech IP yields fairly close agreements at relatively higher temperatures but over-predicts the measurements by 50% at relatively lower temperatures for the three equivalence ratios studied. A new 2-methyl-1-butanol high temperature mechanism was proposed and validated against the Ignition Delay data. Sensitivity analysis for both n-pentanol and iso-pentanol showed the dominance of small radical reactions. Reaction pathway analysis aided further scrutiny of the fuel-specific reactions in Mech NP, leading to refinement of the kinetic model, and improved agreement between the predicted and measured Ignition Delay times as well as the jet-stirred reactor results. © 2012 The Combustion Institute.
Jiaxiang Zhang - One of the best experts on this subject based on the ideXlab platform.
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Shock Tube Measurements and Kinetic Investigation on the Ignition Delay Times of Methane/Dimethyl Ether Mixtures
Energy & Fuels, 2020Co-Authors: Chenglong Tang, Jiaxiang Zhang, Zuohua HuangAbstract:In this work, the Ignition Delay times of stoichiometric methane/dimethyl ether (DME) were measured behind the reflected shock waves over a wide range of conditions: temperatures between 1134 and 2105 K, pressures of 1, 5, and 10 bar, a DME blending ratio from 0 to 100% (M100 to M0), and an argon concentration of 95%. The present shock tube facility was validated by comparing the measured Ignition Delay times of DME with literature values and was used for measurement of the subsequent methane/DME Ignition Delay times. The Ignition Delay times of all mixtures exhibit a negative pressure dependence. For a given temperature, the Ignition Delay time of methane/DME decreases remarkably with the presence of only 1% DME. As the DME blending ratio increases, the Ignition Delay times are correspondingly decreased; however, the Ignition promotion effect of DME is decreased. The calculated Ignition Delay times of methane/DME mixtures using two recently developed kinetic mechanisms are compared with those of measurem...
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experimental and kinetic study on Ignition Delay times of dme h2 o2 ar mixtures
Combustion and Flame, 2014Co-Authors: Erjiang Hu, Jiaxiang Zhang, Zihang Zhang, Zuohua HuangAbstract:Abstract Ignition Delay times of dimethyl ether (DME)/hydrogen/oxygen/argon mixtures (hydrogen blending ratio ranging from 0% to 100%) were measured behind reflected shock waves at pressures of 1.2–10 atm, temperature range of 900–1700 K, and for the lean ( ϕ = 0.5), stoichiometric ( ϕ = 1.0) and rich ( ϕ = 2.0) mixtures. For more understanding the effect of initial parameters, correlations of Ignition Delay times for the lean mixtures were obtained on the basis of the measured data ( X H2 ⩽ 95%) through multiple linear regression. Ignition Delay times of the DME/H 2 mixtures demonstrate three Ignition regimes. For X H2 ⩽ 80%, the Ignition is dominated by the DME chemistry and Ignition Delay times show a typical Arrhenius dependence on temperature and pressure. For 80% ⩽ X H2 ⩽ 98%, the Ignition is dominated by the combined chemistries of DME and hydrogen, and Ignition Delay times at higher pressures give higher Ignition activation energy. However, for X H2 ⩾ 98%, the transition in activation energy for the mixture was found as decreasing the temperature, indicating that the Ignition is dominated by the hydrogen chemistry. Simulations were made using two available models and different results were presented. Thus, sensitivity analysis was performed to illustrate the causes of different simulation results of the two models. Subsequently, chemically interpreting on the effect of hydrogen blending ratio on Ignition Delay times was made using small radical mole fraction and reaction pathway analysis. Finally, high-pressure simulations were performed, serving as a starting point for the future work.
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high temperature Ignition Delay times of c5 primary alcohols
Combustion and Flame, 2013Co-Authors: Chenglong Tang, Jiaxiang Zhang, Zuohua HuangAbstract:Abstract Ignition Delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-methyl-1-butanol) were measured behind reflected shock waves. Experiments were conducted in the temperature range of 1100–1500 K, pressures of 1.0 and 2.6 atm, equivalence ratios of 0.25, 0.5 and 1.0, and O2 concentration in the fuel/O2/Ar mixtures varying from 3.75% to 15%. Measurements show that the Ignition Delay time and the global activation energy of the three isomers both decrease in the order of iso-pentanol, 2-methyl-1-butanol, and n-pentanol. Chemical kinetic mechanisms for n-pentanol (Mech NP) and iso-pentanol (Mech IP), recently developed by Dagaut and co-workers, were used to model the respective Ignition Delay times. Results show that Mech NP yields close agreement at the equivalence ratio of 0.25, but the agreement is moderated with increasing equivalence ratio. Mech IP yields fairly close agreements at relatively higher temperatures but over-predicts the measurements by 50% at relatively lower temperatures for the three equivalence ratios studied. A new 2-methyl-1-butanol high temperature mechanism was proposed and validated against the Ignition Delay data. Sensitivity analysis for both n-pentanol and iso-pentanol showed the dominance of small radical reactions. Reaction pathway analysis aided further scrutiny of the fuel-specific reactions in Mech NP, leading to refinement of the kinetic model, and improved agreement between the predicted and measured Ignition Delay times as well as the jet-stirred reactor results.
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experimental and kinetic studies on Ignition Delay times of dimethyl ether n butane o2 ar mixtures
Energy & Fuels, 2013Co-Authors: Erjiang Hu, Jiaxiang Zhang, Zuohua Huang, Xue Jiang, Zihang ZhangAbstract:Ignition Delay times of stoichiometric dimethyl ether (DME) and n-butane blends were measured using shock tube at varied DME blending ratios (0, 30, 70, and 100%), temperatures (1200–1600 K), and pressures (1.2–5.3 atm). Simulation work was conducted using the Chemkin code with a NUI C4_47 mechanism. Correlations of Ignition Delay times were obtained on the basis of the measured data through multiple linear regressions. Results show that the Ignition Delay times increase linearly with the increase of 1000/T, and this indicates that the overall activation energy is kept unchanged at the conditions in the study. Increasing pressure decreases the Ignition Delay time. Ignition Delay time decreases with the increase of the DME blending ratio. The peak mole fractions of H and OH radicals increase, and the timing at the peak value of H and OH radicals advances as DME increases. Analysis on the reaction pathway shows that, at high temperatures, hydrogen-abstraction reactions play a dominant role in the consumptio...
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High temperature Ignition Delay times of C5 primary alcohols
Combustion and Flame, 2013Co-Authors: Chenglong Tang, Liangjie Wei, Xingjia Man, Jiaxiang Zhang, Zuohua Huang, Chung K. LawAbstract:Ignition Delay times of the three C5 primary alcohol isomers (n-pentanol, iso-pentanol and 2-methyl-1-butanol) were measured behind reflected shock waves. Experiments were conducted in the temperature range of 1100-1500K, pressures of 1.0 and 2.6atm, equivalence ratios of 0.25, 0.5 and 1.0, and O2concentration in the fuel/O2/Ar mixtures varying from 3.75% to 15%. Measurements show that the Ignition Delay time and the global activation energy of the three isomers both decrease in the order of iso-pentanol, 2-methyl-1-butanol, and n-pentanol. Chemical kinetic mechanisms for n-pentanol (Mech NP) and iso-pentanol (Mech IP), recently developed by Dagaut and co-workers, were used to model the respective Ignition Delay times. Results show that Mech NP yields close agreement at the equivalence ratio of 0.25, but the agreement is moderated with increasing equivalence ratio. Mech IP yields fairly close agreements at relatively higher temperatures but over-predicts the measurements by 50% at relatively lower temperatures for the three equivalence ratios studied. A new 2-methyl-1-butanol high temperature mechanism was proposed and validated against the Ignition Delay data. Sensitivity analysis for both n-pentanol and iso-pentanol showed the dominance of small radical reactions. Reaction pathway analysis aided further scrutiny of the fuel-specific reactions in Mech NP, leading to refinement of the kinetic model, and improved agreement between the predicted and measured Ignition Delay times as well as the jet-stirred reactor results. © 2012 The Combustion Institute.
David F Davidson - One of the best experts on this subject based on the ideXlab platform.
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Ignition Delay time correlations for distillate fuels
Fuel, 2017Co-Authors: David F Davidson, Jiankun Shao, Ronald K. HansonAbstract:Abstract Ignition Delay times were measured behind reflected shock waves in a shock tube for a wide variety of distillate fuels over a range of temperatures, pressures and mixtures. The fuels studied include: jet fuels (JP-5, JP-8, and Jet A), rocket propellants (RP-2), diesel fuels (F-76 and DF-2) and gasoline. A simple correlation was found to describe the Ignition Delay times for all these fuel/air experiments for equivalence ratios near unity, temperatures from 1000 to 1400 K, and pressures from 6 to 60 atm. A simple correlation was also found for low-fuel-concentration experiments diluted in argon. Previously published Ignition Delay time data were found to be in good agreement with these correlations. Finally, for several fuels studied, systematic variations were seen in the activation energy for Ignition Delay time measurements with varying equivalence ratio and oxygen concentration.
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Ignition Delay times of conventional and alternative fuels behind reflected shock waves
Proceedings of the Combustion Institute, 2015Co-Authors: Sijie Li, David F Davidson, Ronald K. HansonAbstract:Abstract The auto-Ignition characteristics of two distillate jet fuels and fifteen alternative fuels (including fuel blends) were investigated using shock-tube/laser-absorption methods. Ignition Delay times were measured behind reflected shock waves over a range of temperatures, 1047–1520 K, and equivalence ratios, 0.25–2.2, in two pressure and mixture regimes: for fuel/air mixtures at 2.07–8.27 atm, and for fuel/4%oxygen(O 2 )/argon(Ar) mixtures at 15.9–44.0 atm. In both pressure ranges, the Ignition Delay times of the alternative fuels and the blends with conventional fuels were found to be similar to those of conventional fuels but with some small systematic differences manifesting the different fuel types. In particular, for alternative aviation fuels, alcohol-to-jet fuels were found to be generally less reactive than Fischer–Tropsch paraffinic kerosenes or hydro-processed renewable jet fuels. Comparisons were also made of the Ignition Delay time data with detailed kinetic modeling for selected fuels. These comparisons show that existing multi-component surrogate/mechanism combinations can successfully predict the behavior of these fuels over the conditions studied. For those fuels lacking kinetic models, the current Ignition Delay time measurements provide useful target data for development and validation of relevant surrogate mixtures and reaction mechanisms.
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shock tube measurements of branched alkane Ignition Delay times
Fuel, 2014Co-Authors: Sijie Li, David F Davidson, Ashley Campos, Ronald K. HansonAbstract:Abstract Ignition Delay times for three branched alkanes: 2,4-dimethylpentane, 2,5-dimethylhexane and iso-octane, were measured behind reflected shock waves. The Ignition Delay time measurements cover the temperature range of 1313–1554 K, with pressures near 1.5 and 3 atm, equivalence ratios of 0.5 and 1 in 4% oxygen/argon. Regression analyses of the data over the limited range of conditions studied yield the following correlations for Ignition Delay time as a function of temperature (K), pressure (atm), and equivalence ratio: 2,4-DMP: τ ign [s] = 8.4 × 10 −11 P −0.61 Φ 1.03 exp(46.6[kcal/mol]/RT) 2,5-DMH: τ ign [s] = 2.1 × 10 −10 P −0.60 Φ 0.99 exp(43.4[kcal/mol]/RT) Iso-octane: τ ign [s] = 1.1 × 10 −10 P −0.47 Φ 0.86 exp(45.7[kcal/mol]/RT) Comparing the current Ignition Delay time data of branched alkanes with published values for their normal alkane isomers, it was confirmed that increasing the degree of carbon chain branching lowers the reactivity of the fuel and increases the Ignition Delay time. In addition, longer Ignition Delay times were observed for 2,4-dimethylpentane than 2,5-dimethylhexane, confirming the influence on reactivity by changing the straight carbon chain by one carbon for symmetric branched hydrocarbon fuels. The low reactivity and long Ignition Delay times for branched alkanes were attributed to the high concentrations of propene and iso-butene formed when branched alkanes decompose, as propene and iso-butene reduce the radical pool by consuming OH, O and H to form less-reactive species like allyl radical and allene. The Ignition Delay times of the fuels studied were also seen to increase monotonically with octane number under the current test conditions.
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Ignition Delay times of methyl oleate and methyl linoleate behind reflected shock waves
Proceedings of the Combustion Institute, 2013Co-Authors: M F Campbell, Ronald K. Hanson, David F Davidson, C K WestbrookAbstract:Abstract Ignition Delay times for methyl oleate (C 19 H 36 O 2 , CAS: 112-62-9) and methyl linoleate (C 19 H 34 O 2 , CAS: 112-63-0) were measured for the first time behind reflected shock waves, using an aerosol shock tube. The aerosol shock tube enabled study of these very-low-vapor-pressure fuels by introducing a spatially-uniform fuel aerosol/4% oxygen/argon mixture into the shock tube and employing the incident shock wave to produce complete fuel evaporation, diffusion, and mixing. Reflected shock conditions covered temperatures from 1100 to 1400 K, pressures of 3.5 and 7.0 atm, and equivalence ratios from 0.6 to 2.4. Ignition Delay times for both fuels were found to be similar over a wide range of conditions. The most notable trend in the observed Ignition Delay times was that the pressure and equivalence ratio scaling were a strong function of temperature, and exhibited cross-over temperatures at which there was no sensitivity to either parameter. Data were also compared to the biodiesel kinetic mechanism of Westbrook et al. (2011) [10] , which underpredicts Ignition Delay times by about 50%. Differences between experimental and computed Ignition Delay times were strongly related to existing errors and uncertainties in the thermochemistry of the large methyl ester species, and when these were corrected, the kinetic simulations agreed significantly better with the experimental measurements.
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shock tube measurements of Ignition Delay times for the butanol isomers
Combustion and Flame, 2012Co-Authors: Ivo Stranic, David F Davidson, Deanna P Chase, Joseph T Harmon, Sheng Yang, Ronald K. HansonAbstract:Abstract Ignition Delay times of the four isomers of butanol were measured behind reflected shock waves over a range of experimental conditions: 1050–1600 K, 1.5–43 atm, and equivalence ratios of 1.0 and 0.5 in mixtures containing 4% O2 diluted in argon. Additional data were also collected at 1.0–1.5 atm in order to replicate conditions used by previous researchers. Good agreement is seen with past work for 1-butanol Ignition Delay times, though our measured data for the other isomers were shorter than those found in some previous studies, especially at high temperatures. At most conditions, the Ignition Delay time increases for each isomer in the following order: 1-butanol, 2-butanol and i-butanol nearly equal, and t-butanol. In addition, t-butanol has a higher activation energy than the other three isomers. In a separate series of high-pressure experiments, Ignition Delay times of 1-butanol in stoichiometric air were measured at temperatures as low as 800 K. At temperatures below 1000 K, pre-Ignition pressure rises as well as significant rollover of Ignition Delay times were observed. Modeling of all collected data using several different chemical kinetic mechanisms shows partial agreement with the experimental data depending on the mechanism, isomer, and conditions. Only the mechanism developed by Vranckx et al. [1] partially explains the rollover and pre-Ignition observed in stoichiometric experiments in air.
