Ignition delay time and H2O measurements during methanol oxidation behind reflected shock waves

Abstract New ignition delay time (IDT) data for stoichiometric natural gas (NG) blends composed of C1 – C5 n-alkanes with methane as the major component were recorded using a high pressure shock tube (ST) at reflected shock pressures (p5) and temperatures (T5) in the range 20–30 bar and 1000–1500 K, respectively. The good agreement of the new IDT experimental data with literature data shows the reliability of the new data at the conditions investigated. Comparisons of simulations using the NUI Galway mechanism (NUIGMech1.0) show very good agreement with the new experimental results and with the existing data available in the literature. Empirical IDT correlation equations have been developed through multiple linear regression analyses for these C1 – C5 n-alkane/air mixtures using constant volume IDT simulations in the pressure range pC = 10–50 bar, at temperatures TC = 950–2000 K and in the equivalence ratio (φ) range 0.3–3.0. Moreover, a global correlation equation is developed using NUIGMech1.0, to predict the IDTs for these NG mixtures and other relevant data available in the literature. The correlation expression utilized in this study employs a traditional Arrhenius rate form including dependencies on the individual fuel fraction, TC, φ and pC.

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

Volume 3: Coal, Biomass, Hydrogen, and Alternative Fuels; Cycle Innovations; Electric Power; Industrial and Cogeneration; Organic Rankine Cycle Power Systems ◽

10.1115/gt2019-90270 ◽

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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Auto-Ignition of Gas Turbine Lubricating Oils in a Shock Tube Using Spray Injection

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4049484 ◽

2021 ◽

Author(s):

Sean P. Cooper ◽

Zachary K. Browne ◽

Sulaiman A. Alturaifi ◽

Olivier E. Mathieu ◽

Eric Petersen

Keyword(s):

Shock Tube ◽

Gas Turbine ◽

Ignition Delay ◽

Delay Time ◽

Ignition Delay Time ◽

Lubricating Oil ◽

Fuel Injector ◽

Lubricating Oils ◽

Reflected Shock ◽

Auto Ignition

Abstract In choosing the lubricating oil for a gas turbine system, properties such as viscosity, viscosity index, corrosion prevention, and thermal stability are chosen to optimize turbine longevity and efficiency. Another property that needs to be considered is the lubricant's reactivity, as the lubricant's ability to resist combustion during turbine operation is highly desirable. In evaluating a method to define reactivity, the extremely low vapor pressure of these lubricants makes conventional vaporization by heating impractical. To this end, a new experiment was designed and tested to evaluate the reactivity of lubricating oils using an existing shock-tube facility at Texas A&M University equipped with an automotive fuel injector. This experiment disperses a pre-measured amount of lubricant into a region of high-temperature air to study auto-ignition. To ensure proper dispersal, a laser extinction diagnostic was used to detect the lubricant particles behind the reflected shock as they are dispersed and vaporized. An OH* chemiluminescence diagnostic was used to determine ignition delay time. Using this method, various 32-, 36-, and 46-weight lubricants identified as widely used in the gas turbine industry were tested. Experiments were conducted in post-reflected shock conditions around 1370 K (2006 ºF) and 1.2 atm, where ignition delay time, peak OH* emission, and time-to-peak values were recorded and compared. Ignition was observed for all but one of the lubricants at these conditions, and mild to strong ignition was observed for the other lubricants with varying ignition delay times.

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Ignition of Lean Methane-Based Fuel Blends at Gas Turbine Pressures

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2720543 ◽

2007 ◽

Vol 129 (4) ◽

pp. 937-944 ◽

Cited By ~ 65

Author(s):

Eric L. Petersen ◽

Joel M. Hall ◽

Schuyler D. Smith ◽

Jaap de Vries ◽

Anthony R. Amadio ◽

...

Keyword(s):

Activation Energy ◽

Temperature Dependence ◽

Gas Turbine ◽

Chemical Kinetics ◽

Ignition Delay ◽

Delay Time ◽

Ignition Delay Time ◽

Ignition Time ◽

Fuel Blends ◽

Reflected Shock

Shock-tube experiments and chemical kinetics modeling were performed to further understand the ignition and oxidation kinetics of lean methane-based fuel blends at gas turbine pressures. Such data are required because the likelihood of gas turbine engines operating on CH4-based fuel blends with significant (>10%) amounts of hydrogen, ethane, and other hydrocarbons is very high. Ignition delay times were obtained behind reflected shock waves for fuel mixtures consisting of CH4, CH4∕H2, CH4∕C2H6, and CH4∕C3H8 in ratios ranging from 90/10% to 60/40%. Lean fuel/air equivalence ratios (ϕ=0.5) were utilized, and the test pressures ranged from 0.54 to 30.0atm. The test temperatures were from 1090K to 2001K. Significant reductions in ignition delay time were seen with the fuel blends relative to the CH4-only mixtures at all conditions. However, the temperature dependence (i.e., activation energy) of the ignition times was little affected by the additives for the range of mixtures and temperatures of this study. In general, the activation energy of ignition for all mixtures except the CH4∕C3H8 one was smaller at temperatures below approximately1300K(∼27kcal∕mol) than at temperatures above this value (∼41kcal∕mol). A methane/hydrocarbon–oxidation chemical kinetics mechanism developed in a recent study was able to reproduce the high-pressure, fuel-lean data for the fuel/air mixtures. The results herein extend the ignition delay time database for lean methane blends to higher pressures (30atm) and lower temperatures (1100K) than considered previously and represent a major step toward understanding the oxidation chemistry of such mixtures at gas turbine pressures. Extrapolation of the results to gas turbine premixer conditions at temperatures less than 800K should be avoided however because the temperature dependence of the ignition time may change dramatically from that obtained herein.

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Auto-Ignition of Gas Turbine Lubricating Oils in a Shock Tube Using Spray Injection

Volume 4A: Combustion, Fuels, and Emissions ◽

10.1115/gt2020-14987 ◽

2020 ◽

Author(s):

Sean P. Cooper ◽

Zachary K. Browne ◽

Sulaiman A. Alturaifi ◽

Olivier Mathieu ◽

Eric L. Petersen

Keyword(s):

Shock Tube ◽

Gas Turbine ◽

Ignition Delay ◽

Delay Time ◽

Ignition Delay Time ◽

Lubricating Oil ◽

Fuel Injector ◽

Lubricating Oils ◽

Reflected Shock ◽

Auto Ignition

Abstract In choosing the lubricating oil for a gas turbine system, properties such as viscosity, viscosity index, corrosion prevention, and thermal stability are chosen to optimize turbine longevity and efficiency. Another property that needs to be considered is the lubricant’s reactivity, as the lubricant’s ability to resist combustion during turbine operation is highly desirable. In evaluating a method to define reactivity, the extremely low vapor pressure of these lubricants makes conventional vaporization by heating impractical due to the high temperatures and fuel cracking as well as issues with preferential vaporization. To this end, a new experiment was designed and tested to evaluate the reactivity of lubricating oils using an existing shock-tube facility at Texas A&M University equipped with an automotive fuel injector. This experiment disperses a pre-measured amount of lubricant into a region of high-temperature air to study auto-ignition. To ensure proper dispersal, a laser extinction diagnostic was used to measure the lubricant particles behind the reflected shock as they are dispersed and vaporized. An OH* chemiluminescence diagnostic measuring light emitted during combustion at around 306 nm was used to determine ignition delay time. Pressure was also measured at the sidewall and endwall positions for test repeatability and exothermicity of the experiments. The methods were validated by conducting experiments with ethanol and comparing the results to previous heated shock-tube experiments conducted in the same facility. Using this method, various 32-, 36-, and 46-weight lubricants identified as widely used in the gas turbine industry were tested. Experiments were conducted in post-reflected shock conditions around 1370K (2006 °F) and 1.2 atm, where ignition delay time, peak OH* emission and time-to-peak values were recorded and compared. Ignition was observed for all but one of the lubricants at these conditions, and mild to strong ignition was observed for the other lubricants with varying ignition delay times.

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Ignition Delay Time Correlation of C1 - C5 Natural Gas Blends for Intermediate and High Temperature Regime

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.4051908 ◽

2021 ◽

Author(s):

A.A.E.S Mohamed ◽

Amrit Sahu ◽

Snehashish Panigrahy ◽

Gilles Bourque ◽

Henry Curran

Keyword(s):

Natural Gas ◽

Ignition Delay ◽

Delay Time ◽

Ignition Delay Time ◽

Correlation Equation ◽

Time Correlation ◽

Reflected Shock ◽

Global Correlation ◽

Rate Form ◽

Good Agreement

Abstract New ignition delay time (IDT) data for stoichiometric natural gas (NG) blends composed of C1 – C5 n-alkanes with methane as the major component were recorded using a high pressure shock tube (ST) at reflected shock pressures (p5) and temperatures (T5) in the range 20 – 30 bar and 1000 – 1500 K, respectively. The good agreement of the new IDT experimental data with literature data shows the reliability of the new data at the conditions investigated. Comparisons of simulations using the NUI Galway mechanism (NUIGMech1.0) show very good agreement with the new experimental results and with the existing data available in the literature. Empirical IDT correlation equations have been developed through multiple linear regression analyses for these C1 – C5 n-alkane/air mixtures using constant volume IDT simulations in the pressure range pC = 10 – 50 bar, at temperatures TC = 950 – 2000 K and in the equivalence ratio (f) range 0.3 – 3.0. Moreover, a global correlation equation is developed using NUIGMech1.0, to predict the IDTs for these NG mixtures and other relevant data available in the literature. The correlation expression utilized in this study employs a traditional Arrhenius rate form including dependencies on the individual fuel fraction, TC, f and pc.

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