scholarly journals Hierarchical Auto-Ignition and Structure-Reactivity Trends of C2–C4 1-Alkenes

Energies ◽  
2021 ◽  
Vol 14 (18) ◽  
pp. 5797
Author(s):  
Wuchuan Sun ◽  
Yingjia Zhang ◽  
Yang Li ◽  
Zuohua Huang
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Chemical Reactivity ◽  
Reaction Pathways ◽  
Propene Oxidation ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Wide Range ◽  
Delay Times

Ignition delay times of small alkenes are a valuable constraint for the refinement of the core kinetic mechanism of hydrocarbons used in representing combustion properties of real fuels. Moreover, the chemical reactivity comparison of those small alkenes provides a reference in object-oriented fuel design and logical combustion utilization. In this study, the ignition delay times of C2–C4 alkenes (ethylene, propene and 1-butene) were measured behind reflected shock waves first, with a fixed oxygen concentration (XO2 = 6%) and equivalence ratio (φ = 1.0) at various pressures of 1.2, 4.0 and 16.0 atm, in order to facilitate the comparison. Three chemical-based-Arrhenius-type correlations covering a wide range of temperature, pressure, equivalence ratio, and dilution were proposed. The simplified reaction network for pyrolysis and oxidation of 1-alkenes was depicted relying on the reaction classes of alkenes. Nine generally accepted mechanisms were used to simulate the ignition delay times measured by this study as well as literature. All the kinetic models show reasonable structure-reactivity trends for all of the three alkenes, but only NUIGMech 1.1 is capable of representing quantificationally the chemical reactivity at all tested conditions. Generally, ethylene exhibits the highest reactivity while propene presents the lowest at high temperatures. Analyses of sensitivity and flux indicate that the main oxidation pathway of ethylene is chain-branching, which accelerates the accumulation of free radical pools, especially for the Ḣ atom, Ȯ atom and ȮH radical, which results in the highest reactivity of ethylene. For propene and 1-butene, due to the presence of the allylic site, consumption of allylic radicals becomes the decisive step of oxidation and allylic radicals are mostly consumed by the HȮ2 radical. However, there are no such efficient reaction pathways for the formation of HȮ2 radicals during the propene oxidation process, while reaction pathways for HȮ2 formation in 1-butene are efficient. Thus, 1-butene presents higher reactivity compared to propene.

scholarly journals Investigation of glycerol doping on ignition delay times and laminar burning velocities of gasoline and diesel fuel

2017 ◽  
Vol 169 (2) ◽  
pp. 167-175
Author(s):  
Agnieszka JACH ◽  
Ilona CIEŚLAK ◽  
Andrzej TEODORCZYK
Keyword(s):  
Diesel Engine ◽  
Diesel Fuel ◽  
Ignition Delay ◽  
Equivalence Ratio ◽  
Molar Fraction ◽  
Cetane Number ◽  
Biodiesel Production ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Delay Times

Glycerol is a major by-product of biodiesel production. Per one tone of produced biodiesel, one hundred kilograms of glycerol is produced. Production of glycerol is increasing due to increase of demand for biodiesel. One of methods of glycerol utilization is combustion. Recent experimental studies with use of a diesel engine and a constant volume combustion chamber show that utilization of glycerol as a fuel results in lower NOx emissions in exhaust gases. It combusts slower than light fuel oil, what is explained by higher viscosity and density of glycerol. Glycerol has low cetane number, so to make combustion in a diesel engine possible at least one of the following conditions need to be fulfilled: a pilot injection, high temperature or high compression ratio. The aim of the paper is to compare glycerol to diesel and to assess influence of glycerol doping on gasoline and diesel fuel in dependence of pressure, temperature and equivalence ratio. The subject of this study is analysis of basic properties of flammable mixtures, such as ignition delay times and laminar burning velocities of primary reference fuels (diesel: n-heptane and gasoline: iso-octane). Calculations are performed with use of Cantera tool in Matlab and Python environments. Analyses of influence of glycerol on ignition delay times of n-heptane/air and iso-octane/air mixtures covered wide range of conditions: temperatures from 600 to 1600 K, pressure 10-200 bar, equivalence ratio 0.3 to 14, molar fraction of glycerol in fuel 0-1 in air. Simulations of LBV in air cover temperatures: 300 K and 500 K, pressures: 10, 40, 100, 200 bar and equivalence ratio from 0.3 to 1.9. Physicochemical properties of gasoline, diesel and glycerol are compared.

scholarly journals PENENTUAN ANGKA OKTANA BAHAN BAKAR KOMERSIAL DENGAN MENGGUNAKAN MODEL KINETIKA OKSIDASI DAN PEMBAKARAN HIDROKARBON MULTIKOMPONEN

REAKTOR ◽  
2012 ◽  
Vol 14 (2) ◽  
pp. 109 ◽  
Author(s):  
Yuswan Muharam ◽  
Chandra Hadiwijaya ◽  
Jacquin Suryadi
Keyword(s):  
Old Age ◽  
Ignition Delay ◽  
Equivalence Ratio ◽  
Initial Pressure ◽  
Volume Percentage ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Commercial Fuel ◽  
Good Agreement

One of the characteristics of gasoline fuel is anti-knock property represented by its octanenumber. The determination of octane numbers in Indonesia is by using cooperative fuel researchengines. The usage of cooperative fuel research engines in Indonesia has constraints, i.e. the limitednumber of the units and the old age. This study aims to obtain the octane numbers of commercialfuels by using kinetic models. The kinetics models of the oxidation and combustion of primaryreference fuel and multi component hydrocarbons are used to calculate the ignition delay times ofprimary reference fuel and commercial fuels, respectively. The ignition delay times of primaryreference fuel and commercial fuels are calculated at the same initial pressure and temperature, aswell as the same equivalence ratio. The octane number of a commercial fuel is known if its ignitiondelay time agrees with that of PFR possessing a certain volume percentage of isooctane. The modelgenerates the octane numbers of commercial fuels BB-A being 92.5, BB-B being 94.5, BB-C being89, BB-D being 90.5 and BB-E being 91.5 with the good agreement with those claimed by the fuelproducers. Salah satu karakteristik bahan bakar bensin adalah sifat anti ketukan yang dinyatakan dengan angkaoktana. Penentuan angka oktana di Indonesia menggunakan mesin CFR (cooperative fuel research).Pemakaian mesin CFR di Indonesia memiliki kendala, yaitu jumlah unit terbatas dan usia tua.Penelitian ini bertujuan mendapatkan angka oktana bahan bakar komersial dengan menggunakanmodel kinetika. Model kinetika oksidasi dan pembakaran bahan bakar rujukan utama dan modelhidrokarbon multikomponen yang telah divalidasi masing-masing digunakan untuk menghitungwaktu tunda ignisi bahan bakar rujukan utama dan bahan bakar komersial. Waktu tunda ignisibahan bakar rujukan utama dan bahan bakar komersial dihitung pada tekanan dan temperatur awal,serta rasio ekuivalensi yang sama. Angka oktana suatu bahan bakar komersial diketahui apabilawaktu tunda ignisinya cocok dengan waktu tunda ignisi bahan bakar rujukan utama yang memilikipersen volume isooktana tertentu. Model menghasilkan angka oktana bahan bakar komersial BB-Asebesar 92,5, BB-B 94,5, BB-C 89, BB-D 90,5 dan BB-E 91,5 yang memiliki ketepatan yang tinggiterhadap klaim produser bahan bakar komersial.

Low hydrocarbon mixtures ignition delay times investigation behind reflected shock waves

Shock Waves ◽  
2002 ◽  
Vol 11 (4) ◽  
pp. 309-322 ◽  
Author(s):  
N. Lamoureux ◽  
C.-E. Paillard ◽  
V. Vaslier
Keyword(s):  
Shock Waves ◽  
Ignition Delay ◽  
Hydrocarbon Mixtures ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times

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.

scholarly journals Alternative Fuels Based on Biomass: An Experimental and Modeling Study of Ethanol Cofiring to Natural Gas

2015 ◽  
Vol 137 (9) ◽  
Author(s):  
Marina Braun-Unkhoff ◽  
Jens Dembowski ◽  
Jürgen Herzler ◽  
Jürgen Karle ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Power Generation ◽  
Natural Gas ◽  
Gas Turbine ◽  
Kinetic Modeling ◽  
Ignition Delay ◽  
Chemical Kinetic ◽  
Parameter Range ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times

In response to the limited resources of fossil fuels as well as to their combustion contributing to global warming through CO2 emissions, it is currently discussed to which extent future energy demands can be satisfied by using biomass and biogenic by-products, e.g., by cofiring. However, new concepts and new unconventional fuels for electric power generation require a re-investigation of at least the gas turbine burner if not the gas turbine itself to ensure a safe operation and a maximum range in tolerating fuel variations and combustion conditions. Within this context, alcohols, in particular, ethanol, are of high interest as alternative fuel. Presently, the use of ethanol for power generation—in decentralized (microgas turbines) or centralized gas turbine units, neat, or cofired with gaseous fuels like natural gas (NG) and biogas—is discussed. Chemical kinetic modeling has become an important tool for interpreting and understanding the combustion phenomena observed, for example, focusing on heat release (burning velocities) and reactivity (ignition delay times). Furthermore, a chemical kinetic reaction model validated by relevant experiments performed within a large parameter range allows a more sophisticated computer assisted design of burners as well as of combustion chambers, when used within computational fluid dynamics (CFD) codes. Therefore, a detailed experimental and modeling study of ethanol cofiring to NG will be presented focusing on two major combustion properties within a relevant parameter range: (i) ignition delay times measured in a shock tube device, at ambient (p = 1 bar) and elevated (p = 4 bar) pressures, for lean (φ = 0.5) and stoichiometric fuel–air mixtures, and (ii) laminar flame speed data at several preheat temperatures, also for ambient and elevated pressure, gathered from literature. Chemical kinetic modeling will be used for an in-depth characterization of ignition delays and flame speeds at technical relevant conditions. An extensive database will be presented identifying the characteristic differences of the combustion properties of NG, ethanol, and ethanol cofired to NG.

Ignition Delay Times of Syngas and Methane in sCO2 Diluted Mixtures for Direct-Fired Cycles

2019 ◽  
Author(s):  
Samuel Barak ◽  
Owen Pryor ◽  
Erik Ninnemann ◽  
Sneha Neupane ◽  
Xijia Lu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ignition Delay ◽  
High Pressures ◽  
Chemical Kinetic ◽  
Time Data ◽  
Fuel Loading ◽  
Supercritical Regime ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times

Abstract In this study, a shock tube is used to investigate combustion tendencies of several fuel mixtures under high carbon dioxide dilution and high fuel loading. Individual mixtures of oxy-syngas and oxy-methane fuels were added to CO2 bath gas environments and ignition delay time data was recorded. Reflected shock pressures maxed around 100 atm, which is above the critical pressure of carbon dioxide in to the supercritical regime. In total, five mixtures were investigated within a temperature range of 1050–1350K. Ignition delay times of all mixtures were compared with predictions of two leading chemical kinetic computer mechanisms for accuracy. The mixtures included four oxy-syngas and one oxy-methane combinations. The experimental data tended to show good agreement with the predictions of literature models for the methane mixture. For all syngas mixtures though the models performed reasonably well at some conditions, predictions were not able to accurately capture the overall behavior. For this reason, there is a need to further investigate the discrepancies in predictions. Additionally, more data must be collected at high pressures to fully understand the chemical kinetic behavior of these mixtures to enable the supercritical CO2 power cycle development.

High Pressure Ignition Delay Times Measurements and Comparison of the Performance of Several Oxy-Syngas Mechanisms Under High CO2 Dilution

2018 ◽  
Author(s):  
Samuel Barak ◽  
Erik Ninnemann ◽  
Sneha Neupane ◽  
Frank Barnes ◽  
Jayanta Kapat ◽  
...  
Keyword(s):  
Experimental Data ◽  
High Pressure ◽  
Ignition Delay ◽  
Current Data ◽  
High Co2 ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Syngas Combustion ◽  
Data Points

In this study, syngas combustion was investigated behind reflected shock waves in CO2 bath gas to measure ignition delay times and to probe the effects of CO2 dilution. New syngas data were taken between pressures of 34.58–45.50 atm and temperatures of 1113–1275K. This study provides experimental data for syngas combustion in CO2 diluted environments: ignition studies in a shock tube (59 data points in 10 datasets). In total, these mixtures covered a range of temperatures T, pressures P, equivalence ratios φ, H2/CO ratio θ, and CO2 diluent concentrations. Multiple syngas combustion mechanisms exist in the literature for modelling ignition delay times and their performance can be assessed against data collected here. In total, twelve mechanisms were tested and presented in this work. All mechanisms need improvements at higher pressures for accurately predicting the measured ignition delay times. At lower pressures, some of the models agreed relatively well with the data. Some mechanisms predicted ignition delay times which were 2 orders of magnitudes different from the measurements. This suggests there is behavior that has not been fully understood on the kinetic models and are inaccurate in predicting CO2 diluted environments for syngas combustion. To the best of our knowledge, current data are the first syngas ignition delay times measurements close to 50 atm under highly CO2 diluted (85% per vol.) conditions.

Investigating Trends in Simulated Ignition Timing Across a Wide Range of Conditions Including Fuel Reactivity

2012 ◽  
Author(s):  
Michael V. Johnson ◽  
S. Scott Goldsborough ◽  
Timothy A. Smith ◽  
Steven S. McConnell
Keyword(s):  
Ignition Delay ◽  
Equivalence Ratio ◽  
Computational Cost ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Ignition Timing ◽  
Ignition Delay Times ◽  
Wide Range ◽  
Initial Work ◽  
Ci Engines

Continued interest in kinetically-modulated combustion regimes, such as HCCI and PCCI, poses a significant challenge in controlling the ignition timing due to the lack of direct control of combustion phasing hardware available in traditional SI and CI engines. Chemical kinetic mechanisms, validated based on fundamental data from experiments like rapid compression machines and shock tubes, offer reasonably accurate predictions of ignition timing; however utilizing these requires high computational cost making them impractical for use in engine control schemes. Empirically-derived correlations offer faster control, but are generally not valid beyond the narrow range of conditions over which they were derived. This study discusses initial work in the development of an ignition correlation based on a detailed chemical kinetic mechanism for three component gasoline surrogate, composed of n-heptane, iso-octane and toluene, or toluene reference fuel (TRF). Simulations are conducted over a wide range of conditions including temperature, pressure, equivalence ratio and dilution for a range of tri-component blends in order to produce ignition delay time and investigate trends in ignition as pressure, equivalence ratio, temperature and fuel reactivity are varied. A modified, Arrhenius-based power law formulation will be used in a future study to fit the computed ignition delay times.

An Investigation of Combustion Properties of Butanol and its Potential for Power Generation

2017 ◽  
Author(s):  
Torsten Methling ◽  
Sandra Richter ◽  
Trupti Kathrotia ◽  
Marina Braun-Unkhoff ◽  
Clemens Naumann ◽  
...  
Keyword(s):  
Ignition Delay ◽  
Laminar Flame ◽  
Cone Angle ◽  
Transformation Method ◽  
Chemical Kinetic ◽  
Reaction Model ◽  
Ignition Delay Times ◽  
Combustion Properties ◽  
Delay Times ◽  
Reaction Models

Over the last years, global concerns about energy security and climate change have resulted in many efforts focusing on the potential utilization of non-petroleum-based, i.e. bio-derived, fuels. In this context, n-butanol has recently received high attention because it can be produced sustainably. A comprehensive knowledge about its combustion properties is inevitable to ensure an efficient and smart use of n-butanol if selected as a future energy carrier. In the present work, two major combustion characteristics, here laminar flame speeds applying the cone-angle method and ignition delay times applying the shock tube technique, have been studied, experimentally and by modeling exploiting detailed chemical kinetic reaction models, at ambient and elevated pressures. The in-house reaction model was constructed applying the RMG-method. A linear transformation method recently developed, linTM, was exploited to generate a reduced reaction model needed for an efficient, comprehensive parametric study of the combustion behavior of n-butanol/hydrocarbon mixtures. All experimental data were found to agree with the model predictions of the in-house reaction model, for all temperatures, pressures, and fuel-air ratios. On the other hand, calculations using reaction models from the open literature mostly overpredict the measured ignition delay times by about a factor of two. The results are compared to those of ethanol, with ignition delay times very similar and laminar flame speeds of n-butanol slightly lower, at atmospheric pressure.

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