Theoretical Prediction of Laminar Burning Speed and Ignition Delay Time of Gas-to-Liquid Fuel

2016 ◽  
Vol 139 (2) ◽  
Author(s):  
Guangying Yu ◽  
Omid Askari ◽  
Fatemeh Hadi ◽  
Ziyu Wang ◽  
Hameed Metghalchi ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Synthetic Jet ◽  
Operating Conditions ◽  
Chemical Mechanism ◽  
Chemical Mechanisms ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times ◽  
Gas To Liquid ◽  
Laminar Burning Speed

Gas-to-liquid (GTL), an alternative synthetic jet fuel derived from natural gas through Fischer–Tropsch (F–T) process, has gained significant attention due to its cleaner combustion characteristics when compared to conventional counterparts. The effect of chemical composition on key performance aspects such as ignition delay, laminar burning speed, and emission characteristics has been experimentally studied. However, the development of chemical mechanism to predict those parameters for GTL fuel is still in its early stage. The GTL aviation fuel from Syntroleum Corporation, S-8, is used in this study. For theoretical predictions, a mixture of 32% iso-octane, 25% n-decane, and 43% n-dodecane by volume is considered as the surrogate for S-8 fuel. In this work, a detailed kinetics model (DKM) has been developed based on the chemical mechanisms reported for the GTL fuel. The DKM is employed in a constant internal energy and constant volume reactor to predict the ignition delay times for GTL over a wide range of temperatures, pressures, and equivalence ratios. The ignition delay times predicted using DKM are validated with those reported in the literature. Furthermore, the steady one-dimensional premixed flame code from CANTERA is used in conjunction with the chemical mechanisms to predict the laminar burning speeds for GTL fuel over a wide range of operating conditions. Comparison of ignition delay and laminar burning speed shows that the Ranzi et al. mechanism has a better agreement with the available experimental data, and therefore is used for further evaluation in this study.

Theoretical Prediction of Laminar Burning Speed and Ignition Delay of Gas to Liquid Fuel

2016 ◽  
Author(s):  
Guangying Yu ◽  
Omid Askari ◽  
Fatemeh Hadi ◽  
Ziyu Wang ◽  
Hameed Metghalchi ◽  
...  
Keyword(s):  
Chemical Kinetics ◽  
Ignition Delay ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times ◽  
Chemical Kinetic Mechanism ◽  
Gas To Liquid ◽  
Laminar Burning Speed

Gas to Liquid (GTL), an alternative synthetic jet fuel derived from natural gas has gained significant attention recently due to its cleaner combustion characteristics when compared to conventional counterparts. The effect of chemical composition on key performance aspects such as ignition delay time, laminar burning speed, and emission characteristics have been experimentally studied. However, the development of chemical kinetics mechanism to predict those parameters for GTL fuel is still in its early stage. In this work, a detailed kinetics model (DKM) has been developed based on the chemical kinetics reported for GTL surrogate fuels. The DKM is applied to the chemical kinetic mechanism of 597 species and 3853 reactions. The DKM is employed in a constant internal energy and constant volume reactor to predict the ignition delay times for GTL and its three surrogates over a wide range of initial temperature, pressure and equivalence ratio. The ignition delay times predicted using DKM are validated with those reported in the literature. Furthermore, the CANTERA freely propagating 1D flame code is used in conjunction with the chemical kinetic mechanism to predict the laminar burning speeds for GTL fuel over a wide range of operating conditions.

scholarly journals Detailed kinetic model of oxidation and combustion of n-heptane using an automatic generation of mechanisms

2018 ◽  
Vol 5 (1) ◽  
pp. 392
Author(s):  
Yuswan Muharam
Keyword(s):  
Kinetic Model ◽  
Shock Tube ◽  
Ignition Delay ◽  
Operating Conditions ◽  
Pollutant Emission ◽  
Reflected Shock Wave ◽  
Shock Tubes ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times

There is continued interest in developing a better understanding of the oxidation and combustion of large hydrocarbons, which are good representative for practical fuels used in automotive engines for a wide range of operating conditions. This interest is motivated by the need to improve the efficiency and performance of currently operating combustion systems, the fuel economy, and the need to reduce pollutant emission. Normal-heptane is one of these hydrocarbons.  In this work a detailed chemical kinetic model for the oxidation and combustion of n-heptane has been automatically developed using a computer code called MOLEC. The model consisting of 486 species taking part in 2008 elementary reactions was used to reproduce experimental results of n-heptane oxidation in shock tubes. The experimental study of the ignition delay times of n-heptane/O2/Ar behind a reflected shock wave for equivalence ratios of 0.5-4.0 in a temperature range of 1300 K- 2000 K can be reproduced well by the model. Experimentally derived and numerically predicted ignition delays of n-heptane/air mixtures in a high-pressure shock tube in a wide range of temperatures, pressures, and equivalence ratios agree very well. Sensitivity analyses were performed for shock tube environment in an attempt to identify the most important reactions under the relevant conditions of study.Keywords: Modelling, Oxidation, Combustion, Kinetics, Fuels AbstrakDewasa ini di dunia muncul minat yang berkelanjutan dalam mengembangkan proses oksidasi dan pembakaran hidrokarbon panjang, yang merupakan representatif yang meyakinkan bagi  bahan bakar praktis yang digunakan di dalam mesin kendaraan bermotor dalam rentang kondisi operasi yang Iebar. Keminatan ini dipicu oleh keinginan untuk meningkatkan efisiensi dan kinerja sistem pembakaran yang digunakan saat ini, ekonomi bahan bakar serta kebutuhan untuk mengurangi emisi polutan. Normal-heptane merupakan salah satu hidrokarbon ini. Di dalam riset ini sebuah model kinetika kimia detail untuk oksidasi dan pembakaran n-heptana dikembangkan secara otomatis dengan menggunakan sebuah kode komputer yang disebut MOLEC. Model yang terdiri dari 486 spesies yang berperan serta di dalam 2008 reaksi elementer digunakan untuk mereproduksi hasil­ hasil eksperimen oksidasi n-heptana di dalam shock tubes. Has il eksperimen ignition delay times n­ heptana/ O2/Ar di dalam shock tube untuk rasio ekuivalensi 0,5-4,0 pada rentang temperatur 1300 K- 2000 K dapat direproduksi dengan baik oleh model. Ignition delay campuran n-heptanal udara hasil eksperimen dan hasil perhitungan numeris di dalam shock tube bertekanan tinggi dalam rentang temperatur, tekanan, dan rasio ekuivalensi yang luas sangat bersesuaian satu sama lain. Analisis sensitivitas dilakukan dalam upaya mengidentifkasi reaksi-reaksi yang paling penting di dalam kondisi kajian yang relevan.Kata Kunci: Modeling, Oksidasi. Pembakaran, Kinetika, Bahan Bakar

Ignition Characteristics of a Fischer-Tropsch Synthetic Jet Fuel

2008 ◽  
Author(s):  
P. Gokulakrishnan ◽  
M. S. Klassen ◽  
R. J. Roby
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Flow Reactor ◽  
Kinetic Mechanism ◽  
Jet Fuel ◽  
Synthetic Jet ◽  
Jet Fuels ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Ignition Characteristics

Ignition delay times of a “real” synthetic jet fuel (S8) were measured using an atmospheric pressure flow reactor facility. Experiments were performed between 900 K and 1200 K at equivalence ratios from 0.5 to 1.5. Ignition delay time measurements were also performed with JP8 fuel for comparison. Liquid fuel was prevaporized to gaseous form in a preheated nitrogen environment before mixing with air in the premixing section, located at the entrance to the test section of the flow reactor. The experimental data show shorter ignition delay times for S8 fuel than for JP8 due to the absence of aromatic components in S8 fuel. However, the ignition delay time measurements indicate higher overall activation energy for S8 fuel than for JP8. A detailed surrogate kinetic model for S8 was developed by validating against the ignition delay times obtained in the present work. The chemical composition of S8 used in the experiments consisted of 99.7 vol% paraffins of which approximately 80 vol% was iso-paraffins and 20% n-paraffins. The detailed kinetic mechanism developed in the current work included n-decane and iso-octane as the surrogate components to model ignition characteristics of synthetic jet fuels. The detailed surrogate kinetic model has approximately 700 species and 2000 reactions. This kinetic mechanism represents a five-component surrogate mixture to model generic kerosene-type jets fuels, namely, n-decane (for n-paraffins), iso-octane (for iso-paraffins), n-propylcyclohexane (for naphthenes), n-propylbenzene (for aromatics) and decene (for olefins). The sensitivity of iso-paraffins on jet fuel ignition delay times was investigated using the detailed kinetic model. The amount of iso-paraffins present in the jet fuel has little effect on the ignition delay times in the high temperature oxidation regime. However, the presence of iso-paraffins in synthetic jet fuels can increase the ignition delay times by two orders of magnitude in the negative temperature (NTC) region between 700 K and 900 K, typical gas turbine conditions. This feature can have a favorable impact on preventing flashback caused by the premature autoignition of liquid fuels in lean premixed prevaporized (LPP) combustion systems.

Laminar Flame Speed and Ignition Delay Time Data for the Kinetic Modeling of Hydrogen and Syngas Fuel Blends

2013 ◽  
Vol 135 (2) ◽  
Author(s):  
Michael C. Krejci ◽  
Olivier Mathieu ◽  
Andrew J. Vissotski ◽  
Sankaranarayanan Ravi ◽  
Travis G. Sikes ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Chemical Kinetics ◽  
Ignition Delay ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Elevated Pressures ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times

Laminar flame speeds and ignition delay times have been measured for hydrogen and various compositions of H2/CO (syngas) at elevated pressures and elevated temperatures. Two constant-volume cylindrical vessels were used to visualize the spherical growth of the flame through the use of a schlieren optical setup to measure the laminar flame speed of the mixture. Hydrogen experiments were performed at initial pressures up to 10 atm and initial temperatures up to 443 K. A syngas composition of 50/50 by volume was chosen to demonstrate the effect of carbon monoxide on H2-O2 chemical kinetics at standard temperature and pressures up to 10 atm. All atmospheric mixtures were diluted with standard air, while all elevated-pressure experiments were diluted with a He:O2 ratio of 7:1 to minimize instabilities. The laminar flame speed measurements of hydrogen and syngas are compared to available literature data over a wide range of equivalence ratios, where good agreement can be seen with several data sets. Additionally, an improved chemical kinetics model is shown for all conditions within the current study. The model and the data presented herein agree well, which demonstrates the continual, improved accuracy of the chemical kinetics model. A high-pressure shock tube was used to measure ignition delay times for several baseline compositions of syngas at three pressures across a wide range of temperatures. The compositions of syngas (H2/CO) by volume presented in this study included 80/20, 50/50, 40/60, 20/80, and 10/90, all of which are compared to previously published ignition delay times from a hydrogen-oxygen mixture to demonstrate the effect of carbon monoxide addition. Generally, an increase in carbon monoxide increases the ignition delay time, but there does seem to be a pressure dependency. At low temperatures and pressures higher than about 12 atm, the ignition delay times appear to be indistinguishable with an increase in carbon monoxide. However, at high temperatures the relative composition of H2 and CO has a strong influence on ignition delay times. Model agreement is good across the range of the study, particularly at the elevated pressures.

Investigation of Chemical Kinetic Model for Hypergolic Propellant of Monomethylhydrazine and Nitrogen Tetroxide

2020 ◽  
Vol 143 (6) ◽  
Author(s):  
Hu Hong-bo ◽  
Chen Hong-yu ◽  
Yan Yu ◽  
Zhang Feng ◽  
Yin Ji-Hui ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Flame Temperature ◽  
Chemical Kinetic ◽  
Chemical Mechanism ◽  
Chamber Pressure ◽  
Nitrogen Tetroxide ◽  
Combustion Flame ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Calculation Results

Abstract Hypergolic bipropellant of monomethylhydrazine (MMH) and nitrogen tetroxide (NTO) is extensively used in spacecraft propulsion applications and rocket engines. But studies on the chemical kinetic mechanism of MMH/NTO are limited. So, in this study by integrating the submechanisms of MMH decomposition, NTO thermal decomposition, MMH/NTO and intermediates, and small hydrocarbons, the comprehensive chemical mechanism of MMH/NTO bipropellant is proposed. The present chemical mechanism consists of 72 species and 406 elementary reactions. In two respects of ignition delay times and combustion flame temperatures, the present model has been validated against the theoretical calculation results and also compared with other kinetic models in the literature. The validations show that the predicted ignition delay times by the present kinetic model are highly consistent with the theoretical data and well describe the pressure-dependent characteristic. For combustion flame temperature, the present model also exhibits better predictions to the theoretical calculation results, which are also the same as the predictions by the MMH-RFNA model. Furthermore, the influences of initial temperature, chamber pressure, and NTO/HHM mass ratio (O/F) on the ignition delay time and combustion flame temperature are investigated. The auto-ignition behavior of MMH/NTO propellant is sensitive to initial temperature and chamber pressure, and the combustion flame temperature is more sensitive to the O/F. This study provides a detail chemical kinetics model for further mechanism simplification and combustion numerical simulation.

Constrained-Equilibrium Modeling of Methane Oxidation in Air

2014 ◽  
Vol 136 (3) ◽  
Author(s):  
Ghassan Nicolas ◽  
Mohammad Janbozorgi ◽  
Hameed Metghalchi
Keyword(s):  
Kinetic Model ◽  
Ignition Delay ◽  
Combustion Process ◽  
Rate Equations ◽  
Time Step ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times ◽  
Constrained Equilibrium ◽  
Detailed Kinetic Model

Rate-controlled constrained-equilibrium method has been further developed to model methane/air combustion. A set of constraints has been identified to predict the nonequilibrium evolution of the combustion process. The set predicts the ignition delay times of the corresponding detailed kinetic model to within 10% of accuracy over a wide range of initial temperatures (900 K–1200 K), initial pressures (1 atm–50 atm) and equivalence ratios (0.6–1.2). It also predicts the experimental shock tube ignition delay times favorably well. Direct integration of the rate equations for the constraint potentials has been employed. Once the values of the potentials are obtained, the concentration of all species can be calculated. The underlying detailed kinetic model involves 352 reactions among 60 H/O/N/C1-2 species, hence 60 rate equations, while the RCCE calculations involve 16 total constraints, thus 16 total rate equations. Nonetheless, the constrained-equilibrium concentrations of all 60 species are calculated at any time step subject to the 16 constraints.

Autoignition Study of “Gas-to-Liquid” Fischer-Tropsch Jet Fuels

2019 ◽  
Author(s):  
Sulaiman A. Alturaifi ◽  
Tatyana Atherley ◽  
Olivier Mathieu ◽  
Bing Guo ◽  
Eric L. Petersen
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Ignition Delay Time ◽  
Jet Fuel ◽  
Jet Fuels ◽  
Fischer Tropsch ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Gas To Liquid

Abstract In recent years, there has been an interest in finding a jet fuel alternative to the crude oil-based kerosene. Gas-to-liquid (GtL) fuel is being derived via Fischer-Tropsch synthesis processes by converting natural gas to longer-chain hydrocarbons which form the basis for jet fuel. In this study, new experimental ignition delay time measurements of GtL jet fuels have been determined at elevated pressures and temperatures. The measurements were conducted in a heated, high-pressure shock-tube facility capable of initial temperatures up to 200°C. Two GtL jet fuels were investigated, Shell GTL and Syntroleum S-8, which can be used in aviation applications at concentrations up to 50% blended with conventional oil-based kerosene. The ignition delay time measurements were conducted behind reflected shock waves for gaseous-phase fuel in air at a pressure around 10 atm and over a temperature range of 966 to 1266 K for two equivalence ratios, fuel lean (ϕ = 0.5) and stoichiometric (ϕ = 1.0). Ignition delay time was determined by observing the pressure and electronically excited OH chemiluminescence around 307 nm at the endwall location. Similar ignition delay times were observed for the two fuels at the fuel lean condition, while Syntroleum S-8 showed shorter ignition delay times at the stoichiometric condition. Comparisons are made with ignition delay time measurements for Jet-A previously conducted in the same facility and showed reasonable agreement over the tested conditions. The predictions from the available literature for GtL fuel surrogate kinetics models were obtained and compared with the experimental measurements.

Detailed Chemical Mechanism Generation for Combustion of Ethanol-Air Mixture

2019 ◽  
Author(s):  
Shrabanti Roy ◽  
Fatemeh Hadi ◽  
Omid Askari
Keyword(s):  
High Pressure ◽  
Low Temperature ◽  
Flame Structure ◽  
Operating Conditions ◽  
Chemical Mechanism ◽  
Good Prediction ◽  
Alternative Source ◽  
Chemical Mechanisms ◽  
Wide Range ◽  
Temperature Operating

Abstract Significance of ethanol as an alternative source of renewable energy is increasing every day. In this study a chemical mechanism has been developed to predict the characteristic of ethanol oxidation in a wide range of temperature and pressure of 300–2500 K and 1–50 atm, respectively. The mechanism is generated using reaction mechanism generator (RMG). Sensitivity analysis on the mechanism is done to find the reactions responsible in the deviation of numerical results with experimental data. Rate coefficient of important reactions is corrected with well-accepted data from literature which helps to improve the mechanism against experiment. The validation is done with laminar burning speed and ignition delay time results at various operating conditions. The results show a reasonable agreement in both high pressure and low temperature cases. A good prediction of major species concentration is found in flame structure measurement. A comparison of the current mechanism with other available chemical mechanisms is also presented at different operating conditions. Compared to other mechanisms, this improved mechanism has an advantage of handling the high pressure and low temperature operating conditions within a reasonable time and accuracy.

Numerical Study on the Effect of Real Syngas Compositions on Ignition Delay Times and Laminar Flame Speeds at Gas Turbine Conditions

2013 ◽  
Vol 136 (1) ◽  
Author(s):  
Olivier Mathieu ◽  
Eric L. Petersen ◽  
Alexander Heufer ◽  
Nicola Donohoe ◽  
Wayne Metcalfe ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Delay Time ◽  
Gas Turbines ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Flame Speed ◽  
Operating Conditions ◽  
Laminar Flame Speed ◽  
Ignition Delay Times ◽  
Delay Times

Depending on the feedstock and the production method, the composition of syngas can include (in addition to H2 and CO) small hydrocarbons, diluents (CO2, water, and N2), and impurities (H2S, NH3, NOx, etc.). Despite this fact, most of the studies on syngas combustion do not include hydrocarbons or impurities and in some cases not even diluents in the fuel mixture composition. Hence, studies with realistic syngas composition are necessary to help in designing gas turbines. The aim of this work was to investigate numerically the effect of the variation in the syngas composition on some fundamental combustion properties of premixed systems such as laminar flame speed and ignition delay time at realistic engine operating conditions. Several pressures, temperatures, and equivalence ratios were investigated for the ignition delay times, namely 1, 10, and 35 atm, 900–1400 K, and ϕ = 0.5 and 1.0. For laminar flame speed, temperatures of 300 and 500 K were studied at pressures of 1 atm and 15 atm. Results showed that the addition of hydrocarbons generally reduces the reactivity of the mixture (longer ignition delay time, slower flame speed) due to chemical kinetic effects. The amplitude of this effect is, however, dependent on the nature and concentration of the hydrocarbon as well as the initial condition (pressure, temperature, and equivalence ratio).

Laminar Flame Speed and Ignition Delay Time Data for the Kinetic Modeling of Hydrogen and Syngas Fuel Blends

2012 ◽  
Author(s):  
M. C. Krejci ◽  
O. Mathieu ◽  
A. J. Vissotski ◽  
S. Ravi ◽  
T. G. Sikes ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Ignition Delay ◽  
Ignition Delay Time ◽  
Laminar Flame ◽  
Flame Speed ◽  
Laminar Flame Speed ◽  
Elevated Pressures ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times

Laminar flame speeds and ignition delay times have been measured for hydrogen and various compositions of H2/CO (syngas) at elevated pressures and elevated temperatures. Two constant-volume cylindrical vessels were used to visualize the spherical growth of the flame through the use of a schlieren optical setup to measure the laminar flame speed of the mixture. Hydrogen experiments were performed at initial pressures up to 10 atm and initial temperatures up to 443 K. A syngas composition of 50/50 by volume was chosen to demonstrate the effect of carbon monoxide on H2−O2 chemical kinetics at standard temperature and pressures up to 10 atm. All atmospheric mixtures were diluted with standard air, while all elevated-pressure experiments were diluted with a He:O2 of 7:1 to minimize instabilities. The laminar flame speed measurements of hydrogen and syngas are compared to available literature data over a wide range of equivalence ratios where good agreement can be seen with several data sets. Additionally, an improved chemical kinetics model is shown for all conditions within the current study. The model and the data presented herein agree well, which demonstrates the continual, improved accuracy of the chemical kinetic model. A high-pressure shock tube was used to measure ignition delay times for several baseline compositions of syngas at three pressures across a wide range of temperatures. The compositions of syngas (H2/CO) by volume presented in this study included 80/20, 50/50, 40/60, 20/80, and 10/90, all of which are compared to previously published ignition delay times from a hydrogen-oxygen mixture to demonstrate the effect of carbon monoxide addition. Generally, an increase in carbon monoxide increases the ignition delay time, but there does seem to be a pressure dependency. At low temperatures and pressures higher than about 12 atm, the ignition delay times appear to be indistinguishable with an increase in carbon monoxide. However, at high temperatures the relative composition of H2 and CO has a strong influence on ignition delay times. Model agreement is good across the range of the study, particularly at the elevated pressures. Also, an increase in carbon monoxide causes the activation energy of the mixture to decrease.

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