Autoignition Variation of Biodiesel Surrogates: Influence of Saturation

2013 ◽  
Author(s):  
Weijing Wang ◽  
Sandeep Gowdagiri ◽  
Matthew A. Oehlschlaeger
Keyword(s):  
Low Temperature ◽  
High Temperatures ◽  
Ignition Delay ◽  
Acid Methyl Ester ◽  
Negative Temperature ◽  
Carbon Chain ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Temperature Regimes ◽  
Delay Times

The autoignition of three biodiesel surrogates (methyl decanoate, methyl 9-decenoate, and a mixture of methyl 5-decenoate and methyl 6-decenoate), representative of the organic structures found in fatty-acid methyl ester (FAME) biodiesels, has been studied using the reflected shock technique. Measurements of ignition delay times were carried out at 20 atm for temperatures ranging from 700 to 1300 K, spanning all three regimes of reactivity of interest to diesel engines. At high temperatures (> 900 K) the three surrogate components have indistinguishable ignition delay. While in the negative-temperature-coefficient (NTC) and low-temperature regimes (< 900 K) the deviation in ignition delay based on the location of the double bond with the methyl decenoate carbon chain is around a factor of two. The results show that location of double bonds within FAME biodiesel components will have an important role in governing the NTC and low-temperature reactivity for FAME biodiesels but is unimportant at high-temperatures, of significance for the development of biodiesel surrogates and modeling strategies for diesel engine simulations.

The Shock Tube Autoignition of Biodiesels and Biodiesel Components

2013 ◽  
Author(s):  
Weijing Wang ◽  
Matthew A. Oehlschlaeger
Keyword(s):  
High Temperature ◽  
Methyl Ester ◽  
Shock Tube ◽  
Ignition Delay ◽  
Methyl Esters ◽  
Acid Methyl Ester ◽  
Oh Radicals ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times

The autoignition of fatty-acid methyl ester biodiesels and methyl ester biodiesel components was studied in gas-phase shock tube experiments. Ignition delay times for two reference methyl ester biodiesel fuels, derived from methanol-based transesterification of soybean oil and animal fats, and four primary constituents of all methyl ester biodiesels, methyl palmitate, methyl stearate, methyl oleate, and methyl linoleate, were measured behind reflected shock waves for fuel/air mixtures at temperatures ranging from 900 to 1350 K and at pressures around 10 and 20 atm. Ignition delay times were determined by monitoring pressure and chemiluminescence from electronically-excited OH radicals around 310 nm. The results show similarity in ignition delay times for all methyl ester fuels considered, irrespective of the variations in organic structure, at the high-temperature conditions studied and also similarity in high-temperature ignition delay times for methyl esters and n-alkanes.

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

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.

Effect of 2,5-dimethylfuran addition on ignition delay times of n-heptane at high temperatures

2019 ◽  
Vol 13 (3) ◽  
pp. 464-473 ◽  
Author(s):  
Zhenhua Gao ◽  
Erjiang Hu ◽  
Zhaohua Xu ◽  
Geyuan Yin ◽  
Zuohua Huang
Keyword(s):  
High Temperatures ◽  
Ignition Delay ◽  
Ignition Delay Times ◽  
Delay Times

High Pressure Ignition of Boron in Reduced Oxygen Atmospheres

1995 ◽  
Vol 418 ◽  
Author(s):  
R. O. Foelsche ◽  
M. J. Spalding ◽  
R. L. Burton ◽  
H. Krier
Keyword(s):  
High Pressure ◽  
Water Vapor ◽  
Shock Tube ◽  
Ignition Delay ◽  
Peak Pressure ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Fluorine Compounds ◽  
Delay Times ◽  
Tube Study

AbstractBoron ignition delay times for 24 μm diameter particles have been measured behind the reflected shock at a shock tube endwall in reduced oxygen atmospheres and in a combustion bomb at higher pressures in the products of a hydrogen/oxygen/nitrogen reaction. The shock tube study independently varies temperature (1400 – 3200 K), pressure (8.5, 34 atm), and ignition-enhancer additives (water vapor, fluorine compounds). A combustion chamber is used at a peak pressure of 157 atm and temperature in excess of 2800 K to study ignition delays at higher pressures than are possible in the shock tube.

Ignition Delay Time Measurements of C2HX Fuels and Comparison to Several Detailed Kinetics Mechanisms

2004 ◽  
Author(s):  
Eric L. Petersen ◽  
Joel M. Hall ◽  
Danielle M. Kalitan ◽  
Matthew J. A. Rickard
Keyword(s):  
Ignition Delay ◽  
Conclusive Evidence ◽  
Detailed Chemical Kinetics ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times ◽  
Electronically Excited ◽  
Detailed Kinetics ◽  
Detailed Chemical ◽  
Good Agreement

Recent results from experiments and modeling by the authors are reviewed for the ignition of acetylene, ethylene, and ethane in oxygen/argon mixtures at temperatures between 1000 and 2300 K and pressures near 1 atm. The ignition measurements were obtained behind reflected shock waves using emission from electronically excited OH and CH radicals to monitor the reaction progress. While many discrepancies exist amongst previous studies for these lower-order hydrocarbons, the accuracy afforded by the present experiments provides conclusive evidence verifying the trends seen in certain studies from the literature. Several modern, detailed chemical kinetics mechanisms were compared to the new results with some models showing quite good agreement with both ignition delay times and species profiles, particularly for stoichiometric mixtures. However, improvement is still required to match the entire range of fuel concentrations, temperatures, and mixture ratios, particularly for fuel-rich mixtures.

Ignition Delay Times of Oxy-Syngas and Oxy-Methane in Supercritical CO2 Mixtures for Direct-Fired Cycles

2020 ◽  
Vol 142 (2) ◽  
Author(s):  
Samuel Barak ◽  
Owen Pryor ◽  
Erik Ninnemann ◽  
Sneha Neupane ◽  
Subith Vasu ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ignition Delay ◽  
Supercritical Co2 ◽  
High Pressures ◽  
High Efficiency ◽  
Predictive Accuracy ◽  
Chemical Kinetic ◽  
Reflected Shock ◽  
Ignition Delay Times ◽  
Delay Times

Abstract The direct-fired supercritical CO2 (sCO2) cycles promise high efficiency and reduced emissions while enabling complete carbon capture. However, there is a severe lack of fundamental combustion kinetics knowledge required for the development and operation of these cycles, which operate at high pressures and with high CO2 dilution. Experiments at these conditions are very challenging and costly. In this study, a shock tube was used to investigate the auto-ignition tendencies of several 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 were recorded. Reflected shock pressures neared 100 atm, above the critical pressure of carbon dioxide into the supercritical regime. In total, five mixtures were investigated with a pressure range of 70–100 atm and a temperature range of 1050–1350 K. Measured ignition delay times of all mixtures were compared with two leading chemical kinetic mechanisms for their predictive accuracy. The mixtures included four oxy-syngas and one oxy-methane compositions. The literature mechanisms tended to show good agreement with the data for the methane mixture, while these models were not able to accurately capture all behavior for syngas mixtures tested in this study. For this reason, there is a need to further investigate the discrepancies. To the best of our knowledge, we report the first ignition data for the selected mixtures at these conditions. Current work also highlights the need for further work at high pressures to fully understand the chemical kinetic behavior of these mixtures to enable the sCO2 power cycle development.

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.

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