Academic literature on the topic 'Hydrogen-hydrocarbon blended fuels'
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Journal articles on the topic "Hydrogen-hydrocarbon blended fuels"
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TAKITA, Ken'ichi, Tatsuro TSUKAMOTO, Susumu HASEGAWA, and Takashi NIIOKA. "Detonation of Hydrogen/Hydrocarbon Blended Fuels." Transactions of the Japan Society of Mechanical Engineers Series B 58, no. 554 (1992): 3195–200. http://dx.doi.org/10.1299/kikaib.58.3195.
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Mosisa Wako, Fekadu, Gianmaria Pio, and Ernesto Salzano. "The Effect of Hydrogen Addition on Low-Temperature Combustion of Light Hydrocarbons and Alcohols." Energies 13, no. 15 (July 25, 2020): 3808. http://dx.doi.org/10.3390/en13153808.
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Hydrogen is largely considered as an attractive additive fuel for hydrocarbons and alcohol-fueled engines. Nevertheless, a complete understanding of the interactions between blended fuel mechanisms under oxidative conditions at low initial temperature is still lacking. This study is devoted to the numerical investigation of the laminar burning velocity of hydrogen–hydrocarbon and hydrogen–alcohol fuels under several compositions. Estimations were compared with experimental data reported in the current literature. Additionally, the effects of hydrogen addition on engine performance, NOX, and other pollutant emissions of the mentioned fuels have been thermodynamically analyzed. From the study, it has been observed that the laminar burning velocity of the fuel mixtures increased with increasing hydrogen fractions and the peak value shifted to richer conditions. Besides, hydrogen fraction was found to increase the adiabatic flame temperatures eventually favoring the NOX formation for all fuel blends except the acetylene–hydrogen–air mixture where hydrogen showed a reverse effect. Besides, hydrogen is also found to improve the engine performances and helps to surge thermal efficiency, improve the combustion rate, and lessen other pollutant emissions such as CO, CO2, and unburned hydrocarbons. The model predicted well and in good agreement with the experimental data reported in the recent literature.
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Shamshin, Igor O., Maxim V. Kazachenko, Sergey M. Frolov, and Valentin Y. Basevich. "Deflagration-to-Detonation Transition in Stochiometric Propane–Hydrogen–Air Mixtures." Fuels 3, no. 4 (November 14, 2022): 667–81. http://dx.doi.org/10.3390/fuels3040040.
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Hydrocarbon–hydrogen blends are often considered as perspective environmentally friendly fuels for power plants, piston engines, heating appliances, home stoves, etc. However, the addition of hydrogen to a hydrocarbon fuel poses a potential risk of accidental explosion due to the high reactivity of hydrogen. In this manuscript, the detonability of stoichiometric C3H8–H2–air mixtures is studied experimentally in terms of the run-up time and distance of deflagration to detonation transition (DDT). The hydrogen volume fraction in the mixtures varied from 0 to 1. Three different configurations of detonation tubes were used to ensure the DDT in the mixtures of the various compositions. The measured dependences of the DDT run-up time and distance on the hydrogen volume fraction were found to be nonlinear and, in some cases, nonmonotonic with local maxima. Blended fuel detonability is shown to increase sharply only at a relatively large hydrogen volume fraction (above 70%), i.e., the addition of hydrogen to propane in amounts less than 70% vol. does not affect the detonability of the blended fuel significantly. The observed nonlinear/nonmonotonic dependences are shown to be the manifestation of the physicochemical properties of hydrogen-containing mixtures. An increase in the hydrogen volume fraction is accompanied by effects leading to both an increase and a decrease in mixture sensitivity to the DDT. Thus, on the one hand, the increase in the hydrogen volume fraction increases the mixture sensitivity to DDT due to an increase in the laminar flame velocity and a decrease in the self-ignition delay at isotherms above 1000 K and pressures relevant to DDT. On the other hand, the mixture sensitivity to DDT decreases due to the increase in the speed of sound in the hydrogen-containing mixture, thus leading to a decrease in the Mach number of the lead shock wave propagating ahead of the flame, and to a corresponding increase in the self-ignition delay. Moreover, for C3H8–H2–air mixtures at isotherms below 1000 K and pressures relevant to DDT, the self-ignition delay increases with hydrogen volume fraction.
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Dong, Xue, Graham J. Nathan, Saleh Mahmoud, Peter J. Ashman, Dahe Gu, and Bassam B. Dally. "Global characteristics of non-premixed jet flames of hydrogen–hydrocarbon blended fuels." Combustion and Flame 162, no. 4 (April 2015): 1326–35. http://dx.doi.org/10.1016/j.combustflame.2014.11.001.
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Choudhuri, Ahsan R., and S. R. Gollahalli. "Stability of Hydrogen/Hydrocarbon Blended Fuel Flames." Journal of Propulsion and Power 19, no. 2 (March 2003): 220–25. http://dx.doi.org/10.2514/2.6121.
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Gu¨lder, O¨ L., B. Glavincˇevski, and M. F. Baksh. "Fuel Molecular Structure and Flame Temperature Effects on Soot Formation in Gas Turbine Combustors." Journal of Engineering for Gas Turbines and Power 112, no. 1 (January 1, 1990): 52–59. http://dx.doi.org/10.1115/1.2906477.
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A systematic study of soot formation along the centerlines of axisymmetric laminar diffusion flames of a large number of liquid hydrocarbons, hydrocarbon blends, and aviation turbine and diesel fuels was made. Measurements of the attenuation of a laser beam across the flame diameter were used to obtain the soot volume fraction, assuming Rayleigh extinction. Two sets of hydrocarbon blends were designed such that the molecular fuel composition varied considerably but the temperature fields in the flames were kept practically constant. Thus it was possible to separate the effects of molecular structure and the flame temperature on soot formation. It was quantitatively shown that the smoke point height is a lumped measure of fuel molecular constitution. The developed empirical relationship between soot volume fractions and fuel smoke point and hydrogen-to-carbon ratio was applied to five different combustor radiation data, and good agreement was obtained.
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Razali, Halim, Kamaruzzaman Sopian, Baharuddin Ali, and Ali Sohif Mat. "Hydrogen Blended with Gasoline, Diesel, Natural Gas (NGV) as an Alternative Fuel for ICE in Malaysia." Applied Mechanics and Materials 165 (April 2012): 1–5. http://dx.doi.org/10.4028/www.scientific.net/amm.165.1.
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The instability of petroleum prices in the world market has caused the price of fuel in Malaysia to increase, especially in the transportation sector. As an alternative, the transition to use hydrogen as fuel was already in the study and research on the ability of hydrogen profit for internal combustion engine in the technical aspect. The governments involvement in the research as source of energy has been undertaken by several government agencies such as MOSTI, universities and automotive manufacturing industries. These agencies are responsible for developing activities, mainly for commercialization. The development of hydrogen energy in this country focuses on the role of hydrogen that includes methods of generating, transporting, storage, production, and long-term planning. Diversity in the use of hydrogen for Internal Combustion Engine (ICE) can be applied through many ways; hydrogen as the primary fuel, hydrogen mixed with gasoline, hydrogen mixed with diesel, and hydrogen mixed with NGV. Compatibility acceptance of ICE with hydrogen as an alternative energy can solve many technical problems such as backfire, knocking, and the reduction of hydrocarbon, carbon monoxide and smoke contaminants during engine ignition delay.
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Petersen, Eric L., Joel M. Hall, Schuyler D. Smith, Jaap de Vries, Anthony R. Amadio, and Mark W. Crofton. "Ignition of Lean Methane-Based Fuel Blends at Gas Turbine Pressures." Journal of Engineering for Gas Turbines and Power 129, no. 4 (January 2, 2007): 937–44. http://dx.doi.org/10.1115/1.2720543.
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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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Rakopoulos, C. D., C. N. Michos, and E. G. Giakoumis. "Studying the effects of hydrogen addition on the second-law balance of a biogas-fuelled spark ignition engine by use of a quasi-dimensional multi-zone combustion model." Proceedings of the Institution of Mechanical Engineers, Part D: Journal of Automobile Engineering 222, no. 11 (November 1, 2008): 2249–68. http://dx.doi.org/10.1243/09544070jauto947.
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Although a first-law analysis can show the improvement that hydrogen addition impacts on the performance of a biogas-fuelled spark-ignition (SI) engine, additional benefits can be revealed when the second law of thermodynamics is brought into perspective. It is theoretically expected that hydrogen enrichment in biogas can increase the second-law efficiency of engine operation by reducing the combustion-generated irreversibilities, because of the fundamental differences in the mechanism of entropy generation between hydrogen and traditional hydrocarbon combustion. In this study, an experimentally validated closed-cycle simulation code, incorporating a quasi-dimensional multi-zone combustion model that is based on the combination of turbulent entrainment theory and flame stretch concepts for the prediction of burning rates, is further extended to include second-law analysis for the purpose of quantifying the respective improvements. The analysis is applied for a single-cylinder homogeneous charge SI engine, fuelled with biogas—hydrogen blends, with up to 15 vol% hydrogen in the fuel mixture, when operated at 1500r/min, wide-open throttle, fuel-to-air equivalence ratio of 0.9, and ignition timing of 20° crank angle before top dead centre. Among the major findings derived from the second-law balance during the closed part of the engine cycle is the increase in the second-law efficiency from 40.85 per cent to 42.41 per cent with hydrogen addition, accompanied by a simultaneous decrease in the combustion irreversibilities from 18.25 per cent to 17.18 per cent of the total availability of the charge at inlet valve closing. It is also illustrated how both the increase in the combustion temperatures and the decrease in the combustion duration with increasing hydrogen content result in a reduction in the combustion irreversibilities. The degree of thermodynamic perfection of the combustion process from the second-law point of view is quantified by using two (differently defined) combustion exergetic efficiencies, whose maximum values during the combustion process increase with hydrogen enrichment from 49.70 per cent to 53.45 per cent and from 86.01 per cent to 87.33 per cent, respectively.
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Kumar, M. Senthil, A. Ramesh, and B. Nagalingam. "A Comparison of the Different Methods of Using Jatropha Oil as Fuel in a Compression Ignition Engine." Journal of Engineering for Gas Turbines and Power 132, no. 3 (November 24, 2009). http://dx.doi.org/10.1115/1.3155400.
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Different methods to improve the performance of a jatropha oil based compression ignition engine were tried and compared. A single cylinder water-cooled, direct injection diesel engine was used. Base data were generated with diesel and neat jatropha oil. Subsequently, jatropha oil was converted into its methyl ester by transesterification. Jatropha oil was also blended with methanol and orange oil in different proportions and tested. Further, the engine was modified to work in the dual fuel mode with methanol, orange oil, and hydrogen being used as the inducted fuels and the jatropha oil being used as the pilot fuel. Finally, experiments were conducted using additives containing oxygen, like dimethyl carbonate and diethyl ether. Neat jatropha oil resulted in slightly reduced thermal efficiency and higher emissions. Brake thermal efficiency was 27.3% with neat jatropha oil and 30.3% with diesel. Performance and emissions were considerably improved with the methyl ester of jatropha oil. Dual fuel operation with methanol, orange oil, and hydrogen induction and jatropha oil injection also showed higher brake thermal efficiency. Smoke was significantly reduced from 4.4 BSU with neat jatropha oil to 2.6 BSU with methanol induction. Methanol and orange oil induction reduced the NO emission and increased HC and CO emissions. With hydrogen induction, hydrocarbon and carbon monoxide emissions were significantly reduced. The heat release curve showed higher premixed rate of combustion with all the inducted fuels mainly at high power outputs. Addition of oxygenates like diethyl ether and dimethyl carbonate in different proportions to jatropha oil also improved the performance of the engine. It is concluded that dual fuel operation with jatropha oil as the main injected fuel and methanol, orange oil, and hydrogen as inducted fuels can be a good method to use jatropha oil efficiently in an engine that normally operates at high power outputs. Methyl ester of jatropha oil can lead to good performance at part loads with acceptable levels of performance at high loads also. Orange oil and methanol can be also blended with jatropha oil to improve viscosity of jatropha oil. These produce acceptable levels of performance at all outputs. Blending small quantity of diethyl ether and dimethyl carbonate with jatropha oil will enhance the performance. Diethyl ether seems to be the better of the two.
Dissertations / Theses on the topic "Hydrogen-hydrocarbon blended fuels"
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Dong, Xue. "Simulating high flux solar radiation and assessing its influence on a sooty flame." Thesis, 2016. http://hdl.handle.net/2440/112471.
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Integrating concentrated solar thermal energy into fossil-fuels for the production of power/clean fuels is receiving growing attention as the combination of the two energy sources can provide lower emissions of carbon and other pollutants, lower cost, and continuous supply. Various types of hybrid concepts have been proposed. However, all of these concepts employ stand-alone solar receivers and standalone combustors. The University of Adelaide has developed an alternative approach with which to fully integrate a combustor into a solar cavity receiver. This offers the potential for significant savings from reduced infrastructure investment and reduced start-up and shut-down losses. In addition, this hybrid also results in the direct interaction between concentrated solar radiation and a flame, which is theoretically known to be coupled. However, the influence of concentrated solar radiation (CSR) on the flame has not been experimentally investigated. Hence this thesis aims at filling this gap.
High flux solar simulators, comprising an array of high-intensity-discharge lamps coupled with elliptical reflectors, have been widely employed to study concentrated solar thermal energy systems. The use of electrical solar simulators holds the advantage over natural solar radiation in providing repeatable performance without the variability of the solar resource. Reliable models which predict the heat flux generated by a solar simulator are desirable because they enable efficient and systematic optimization of the system to meet the required trade-off between cost and performance. To this end, a concentric multilayer model of the light source is developed in this study to accurately predict the spatial distribution of the heat flux at the focus using a commercial Monte Carlo ray-tracing code. These simulations were validated with measurements of both the radiant intensity of the light source and the distribution of the concentrated heat flux. Further to that, on the experimentally validated ray tracing model, the geometry and surface reflectance of the additional concentrators were also assessed of two high flux solar simulators: one employs a single lamp, the other uses a seven-lamp array. In addition, the time-resolved spectra of solar simulators employing a metal halide and a xenon arc lamp are also measured, which provides the first experimental results of this kind that acquired from the same spectrometer to allow for direct comparison.
This thesis also reports the first set of measurements of the influence of concentrated solar radiation on the soot volume fraction and temperature in a laminar sooty flame. Detailed laser diagnostics was performed on a laminar sooty flame with and without the irradiance of CSR, because laser diagnostics are demonstrated to hold the advantages of being non-intrusive, lower interferences and of being applicable to environments with high flux radiation. The current measurement using laser induced incandescence shows that the soot volume within the laminar flame was increased by 55% by CSR. In addition, the measurement of temperature using two-line atomic fluorescence shows that the flame temperature was increased by around 8% under CSR.
In addition to the detailed laser diagnostics, an assessment of the influence of soot volume fraction on the global performance of the flames was also performed through a systematic study of flames using fuels of different soot propensities, which is achieved by blending hydrogen into hydrocarbon fuels, with hydrogen volume fraction ranging from 0 to 100%. Results show that flames with higher soot volume fraction have higher radiant fraction and lower NOx emissions.
The principle contribution of the thesis is that the first measurement of the influence of concentrated solar radiation on the soot volume fraction and temperature of a flame was performed, which pushed forward the existing understanding of the interaction between broadband solar radiation and combustion. Its second major contribution is establishing an experimentally validated ray-tracing model that accurately predicts the concentrated heat flux from the solar simulator, and on this model, new design and optimization of solar simulators were performed. While this ray-tracing model is developed for metal halide lamps, the methodology is applicable more generally to solar simulators employing other types of discharge arc lamps.Thesis (Ph.D.) (Research by Publication) -- University of Adelaide, School of Chemical Engineering, 2016
Conference papers on the topic "Hydrogen-hydrocarbon blended fuels"
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Anand, G., M. R. Ravi, and J. P. Subrahmanyam. "Performance and Emissions of Natural Gas and Hydrogen/Natural Gas Blended Fuels in Spark Ignition Engine." In ASME 2005 Internal Combustion Engine Division Spring Technical Conference. ASMEDC, 2005. http://dx.doi.org/10.1115/ices2005-1098.
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The basic intent of the present work is to evaluate the potential of using alternative gaseous fuels like compressed natural gas (CNG) and H2/CNG as a spark ignition (SI) engine (lean burn engines) fuel. Computer modeling of internal combustion engine is useful in understanding the complex processes that occur in the combustion chamber. This research deals with quasi-dimensional, two-zone thermodynamic simulation of four-stroke SI engine fueled with CNG and H2/CNG. The fraction of hydrogen in the H2/CNG blend, for simulation was varied from 0–60% by volume. The developed computer model has been used for the prediction of the combustion and emission characteristics of H2/CNG blended fuel in SI engines, which includes the power, thermal efficiency, cylinder pressure-crank angle history, exhaust emissions (NOx and CO), fuel consumption, combustion duration, ignition delay, etc. Predicted results indicate that the presence of hydrogen in H2/CNG blend can improve combustion duration as it has a higher flame speed. There are increases in oxides of nitrogen emissions, but decrease in carbon monoxide and hydrocarbon emissions, when comparing H2/CNG blended fuel to neat CNG. The validity of the model has been carried out by comparing the computed results with experimental data obtained under same engine setup and operating conditions. The results obtained from the theoretical model when compared with those from experimental ones show a good agreement. Also, the effects of the many operating parameters such as equivalence ratio, engine speed, and spark timing have been studied.
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Shrivastava, Sourabh, Ishan Verma, Rakesh Yadav, Pravin Nakod, and Stefano Orsino. "Comparison of Performance of Flamelet Generated Manifold Model With That of Finite Rate Combustion Model for Hydrogen Blended Flames." In ASME Turbo Expo 2021: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2021. http://dx.doi.org/10.1115/gt2021-60232.
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Abstract International Air Transport Association (IATA) sets a 50% reduction in 2005 CO2 emissions levels by 2050, with no increase in net emissions after 2020 [1]. The association also expects the global aviation demand to double to 8.2 billion passengers per year by 2037. These issues have prompted the aviation industry to focus intensely on adopting sustainable aviation fuels (SAF). Further, reduction in CO2 emission is also an active area of research for land-based power generation gas turbine engines. And fuels with high hydrogen content or hydrogen blends are regarded as an essential part of future power plants. Therefore, clean hydrogen and other hydrogen-based fuels are expected to play a critical role in reducing greenhouse gas emissions in the future. However, the massive difference in hydrogen’s physical properties compared to hydrocarbon fuels, ignition, and flashback issues are some of the major concerns, and a detailed understanding of hydrogen combustion characteristics for the conditions at which gas turbines operate is needed. Numerical combustion analyses can play an essential role in exploring the combustion performance of hydrogen as an alternative gas turbine engine fuel. While several combustion models are available in the literature, two of the most preferred models in recent times are the flamelet generated manifold (FGM) model and finite-rate (FR) combustion model. FGM combustion model is computationally economical compared to the detailed/reduced chemistry modeling using a finite-rate combustion model. Therefore, this paper aims to understand the performance of the FGM model compared to detailed chemistry modeling of turbulent flames with different levels of hydrogen blended fuels. In this paper, a detailed comparison of different combustion characteristics like temperature, species, flow, and NOx distribution using FGM and finite rate combustion models is presented for three flame configurations, including the DLR Stuttgart jet flame [2], Bluff body stabilized Sydney HM1 flame [3] and dry-low-NOx hydrogen micro-mix combustion chamber [4]. One of the FGM model’s essential parameters is to select a suitable definition of the reaction progress variable. The reaction progress variable should monotonically increase from the unburnt region to the burnt region. The definition is first studied using a 1D premixed flame with different blend ratios and then used for the actual cases. 2D/3D simulations for the identified flames are performed using FGM and finite rate combustion models. Numerical results from both these models are compared with the available experimental data to understand FGM’s applicability. The results show that the FGM model performs reasonably well for pure hydrogen and hydrogen blended flames.
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Pachidas, Vassilios A., and Riti Singh. "Investigation of a Fuel Cell-Powered Blended Wing Body Airliner With Boundary Layer Re-Energization." In ASME Turbo Expo 2002: Power for Land, Sea, and Air. ASMEDC, 2002. http://dx.doi.org/10.1115/gt2002-30647.
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The following study was undertaken on the assumption that hydrocarbon-based fuels may not be acceptable in the very long term, because of environmental concerns. A possible future fuel is hydrogen, and this study explores a novel proposition for a civil airliner using hydrogen fuel. The technical challenges of this preliminary investigation were: a) the integration of an electric power plant (Fuel Cell) into a Blended Wing Body (BWB) aircraft, and b) to investigate the possibility of reducing the aircraft’s profile drag by boundary layer re-energization. For the re-energization of the boundary layer and for propulsion during cruise, the study considered High-Speed/High Specific Power (HS/HSP) motors, situated at the trailing edge (TE) of the center body, driving fans. Re-energizing the boundary layer of the center body, would reduce the profile drag of the aircraft and hence, the total fuel burn. The take-off requirements of the aircraft were met, by high by-pass ratio (BPR) turbofan lift engines, operating on hydrogen, for a V/STOL (Pachidis, 2000b).
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Won, Sang Hee, Dalton Carpenter, Stuart Nates, and Frederick L. Dryer. "Derived Cetane Number As Chemical Potential Indicator for Near-Limit Combustion Behaviors in Gas Turbine Applications." In ASME 2018 Power Conference collocated with the ASME 2018 12th International Conference on Energy Sustainability and the ASME 2018 Nuclear Forum. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/power2018-7414.
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The objective of this paper is to elucidate the recently observed strong correlation between derived cetane number (DCN) and lean blow out (LBO) characteristics for both petroleum-derived and alternative jet fuels, as well as their blends. In order to evaluate the variability of fuel physical and chemical properties for petroleum-derived jet fuels, the fuel property database appearing in the DSIC-PQIS 2013 report are rigorously analyzed and compared against fuel-specific data for 17 petroleum-derived and alternative jet fuels and their blends obtained previously in our works. The global combustion characteristics of each fuel for fuel/air mixture were characterized experimentally by determining their combustion property targets (CPTs) — the hydrogen to carbon molar ratio (H/C ratio), the derived cetane number (DCN), the average molecular weight (MW), and surrogate fuel mixtures and threshold sooting index (TSI). Surrogate mixtures of known hydrocarbon species were blended to match the CPTs of target real fuel. The known chemical functional group distributions of the surrogate mixtures for each fuel or fuel blend were then used to predict well-known fundamental combustion behaviors — reflected shock ignition delay times and laminar flame speeds — through quantitative structure-property relationship (QSPR) regression analyses developed from a validation base of single component, binary and ternary mixture database. The results show that the DCN is capable of representing ignition propensity and flame propagating characteristics for both petroleum-derived and alternative jet fuels as well as their mixtures with high fidelity. Finally, the chemical functional group distributions of the real fuels themselves were directly measured using 1H nuclear magnetic resonance (NMR) spectra results. QSPR predictions based upon the experimental NMR functional group measurements are shown to provide a rapid, small sample, characterization tool for predicting the above global combustion behaviors of petroleum derived and alternative jet fuel candidates as well as their blends. Through combustor as well as stirred reactor experiments, fuel DCN has been identified as having major influence on LBO in devices that are sensitive to fuel chemical properties.
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Sullivan-Lewis, Elliot, and Vincent McDonell. "Flameholding Tendencies of Natural Gas and Hydrogen Flames at Gas Turbine Premixer Conditions." In ASME Turbo Expo 2014: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/gt2014-25477.
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Ground based gas turbines are responsible for generating a significant amount of electric power as well as providing mechanical power for a variety of applications. This is due to their high efficiency, high power density, high reliability, and ability to operate on a wide range of fuels. Due to increasingly stringent air quality requirements, stationary power gas turbines have moved to lean-premixed operation. Lean-premixed operation maintains low combustion temperatures for a given turbine inlet temperature, resulting in low NOx emissions while minimizing emissions of CO and hydrocarbons. In addition, to increase overall cycle efficiency, engines are being operated at higher pressure ratios and/or higher combustor inlet temperatures. Increasing combustor inlet temperatures and pressures in combination with lean-premixed operation leads to increased reactivity of the fuel/air mixture, leading to increased risk of potentially damaging flashback. Curtailing flashback on engines operated on hydrocarbon fuels requires care in design of the premixer. Curtailing flashback becomes more challenging when fuels with reactive components such as hydrogen are considered. Such fuels are gaining interest because they can be generated from both conventional and renewable sources and can be blended with natural gas as a means for storage of renewably generated hydrogen. The two main approaches for coping with flashback are either to design a combustor that is resistant to flashback, or to design one that will not anchor a flame if a flashback occurs. An experiment was constructed to determine the flameholding tendencies of various fuels on typical features found in premixer passage ways (spokes, steps, etc.) at conditions representative of a gas turbine premixer passage way. In the present work tests were conducted for natural gas and hydrogen between 3 and 9 atm, between 530 K and 650K, and free stream velocities from 40 to 100 m/s. Features considered in the present study include a spoke in the center of the channel and a step at the wall. The results are used in conjunction with existing blowoff correlations to evaluate flameholding propensity of these physical features over the range of conditions studied. The results illustrate that correlations that collapse data obtained at atmospheric pressure do not capture trends observed for spoke and wall step features at elevated pressure conditions. Also, a notable fuel compositional effect is observed.
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Denman, Bradley M., Jeffrey D. Munzar, and Jeffrey M. Bergthorson. "An Experimental and Numerical Study of the Laminar Flame Speed of Jet Fuel Surrogate Blends." In ASME Turbo Expo 2012: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/gt2012-69917.
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Kerosene-type fuels are the most common aviation fuel, and an understanding of their combustion properties is essential for achieving optimized gas turbine operation. Presently, however, there is lack of experimental flame speed data available by which to validate the chemical kinetic mechanisms necessary for effective computational studies. In this study, premixed jet fuel surrogate blends and commercial kerosene are studied using particle image velocimetry in a stagnation flame geometry. Numerical simulations of each experiment are obtained using the CHEMKIN-PRO software package and the JetSurF 2.0 mechanism. The neat hydrocarbon surrogates investigated include n-decane, methylcyclohexane, and toluene, which represent the alkane, cycloalkane, and aromatic components of conventional aviation fuel, respectively. Two blends are studied in this paper. The first is a binary blend formulated to reproduce the laminar flame speed of aviation fuel using a mixing rule based on the laminar flame speed and adiabatic flame temperature of the hydrocarbon components, weighted by their respective mixture mole fractions. The second blend is a tertiary blend formulated to emulate the hydrogen to carbon ratio of the kerosene studied. All of the considered fuels and blends are studied at three equivalence ratios, corresponding to lean, stoichiometric, and rich conditions, and at several stretch rates. The centreline axial velocity profiles from numerical simulations are directly compared to the measured velocity profiles to validate the mechanism at each condition. The difference between the experimental and simulated reference flame speed is used to infer the true unstretched laminar flame speed of the mixture. These results allow the effectiveness of the different blending methodologies to be assessed.
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Douglas, Christopher M., Stephanie L. Shaw, Thomas D. Martz, Robert C. Steele, David R. Noble, Benjamin L. Emerson, and Timothy C. Lieuwen. "Pollutant Emissions Reporting and Performance Considerations for Hydrogen-Hydrocarbon Fuels in Gas Turbines." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-80971.
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Abstract Hydrogen (H2) fuel for gas turbines is a promising approach for long duration storage and dispatchable utilization of intermittent renewable power. A major global discussion point, however, is the potential air quality impact of hydrogen combustion associated with nitrogen oxide (NOx) emissions. Indeed, several studies in the combustion literature have reported elevated NOx concentrations in terms of dry ppmv NOx at 15% oxygen (O2) as a fuel’s H2 fraction is increased. Yet, as emphasized in this work, this practice of directly comparing emissions on the basis of dry ppmv at a reference O2 concentration (ppmvdr) is inappropriate across hydrogen and hydrocarbon fuel blends due to differing concentration changes induced by drying and referencing the corresponding exhaust gasses. This paper addresses three distinct approaches for comparing emissions consistently across fuel blends. Furthermore, it presents examples that quantify the differences in the apparent pollutant emissions between each approach and the usual ppmvdr reporting practice across the full range of hydrogen-methane mixture ratios. In the first approach, ppmvdr emissions values are related to their actual volume concentration. Here, our calculations demonstrate that hydrogen and methane flames producing the same true pollutant concentration exhibit a 40% relative difference in ppmvdr values, resulting in a significant potential exaggeration of NOx emissions for high %H2 fuels. However, this concentration-based approach does not account for changes in the volumetric flow rate of exhaust gasses or the slightly different amounts of heat release required to achieve the same flame temperature across fuels. These effects are captured naturally in the second approach, where the emissions are quantified in terms of the emitted mass per unit of heat release. With this cycle-independent approach, our comparative calculations at equal mass-per-heat emission rates reveal 36% higher ppmvdr values for hydrogen flames than methane flames. Finally, the third approach accounts not only for the thermodynamic properties of the mixture, but also for the system’s overall cycle efficiency, which is shown to depend weakly upon the fuel composition. This method quantifies emissions in terms of the emitted mass per unit of useful shaft work output, a metric also used by environmental regulators. Illustrative results within a simulated F-class gas turbine cycle are presented, indicating 39% higher ppmvdr values for hydrogen flames at equal mass-per-work emission rates. Hence, in all of the considered approaches, ppmvdr emissions values are inflated for H2 fuel blends relative to hydrocarbon fuels, making them unsuitable for direct comparisons of emissions among conventional and alternative fuels.
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Verma, Ishan, Rakesh Yadav, Sourabh Shrivastava, and Pravin Nakod. "Turbulent Combustion Modeling of Swirl Stabilized Blended CH4/H2 Flames by Using Flamelet Generated Manifold." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-82583.
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Abstract Hydrogen has been identified as one of the key elements of the decarbonization initiatives. The level of maturity with different original equipment manufacturers (OEMs) varies significantly for a 100% H2 gas turbine combustor. The typical standard short-term goal is to blend hydrogen with existing fuel as a promising alternative to meet regulatory standards for emission. A typical Dry Low NOx (DLN) combustion system can handle a certain level of hydrogen blending. However, due to fundamental differences between the properties of hydrogen and methane, existing designs of combustion systems are not capable of handling moderate to high levels of hydrogen blending. Therefore, prior knowledge of blend ratios that a given combustion system can handle is essential for the system’s stable operation. Computational Fluid Dynamic (CFD) simulation can help study the effect of different blend ratios on flame stability, peak temperature, pollutants, etc., without affecting the hardware. Thus, helping in reducing the overall cost and time spent deciding the allowable blend ratios. In this work, the accuracy and consistency of Flamelet Generated Manifold (FGM) with Large Eddy Simulation (LES) have been assessed to model swirling turbulent combustion of CH4/H2 blends for gas turbine engine combustors. FGM characterizes the extent of reaction using a reaction progress variable typically defined as a weighted sum of some representative product species of hydrocarbon combustion like CO and CO2. With H2 blending, the mixture now has multiple heat release time scales, and the prevailing choices of reaction progress definition are not optimal. Therefore, the first and foremost task is to correctly describe the reaction rate by choosing a reaction progress variable with validity over a range of H2 blending ratios and equivalence ratios. Additionally, the variation in the laminar properties of the blended mixture, e.g., thermal conductivity and viscosity, is enhanced when H2 is added to the fuel. In this work, we have used kinetic theory to compute these properties accurately as a function of temperature and composition. The flame configurations used to validate FGM in this work are CH4/H2 swirl flame (SMH1) and HM3e. The burner designs belong to a detailed and widely simulated database from Sydney Swirl Burner, with a CH4/H2 blend ratio of 1:1 (by volume). The FGM generates flamelets from opposed flow diffusion flames and freely propagates premix flame configuration. The solution of both the FGM approaches is compared with Finite Rate detailed chemistry solution, and definitive advantages/disadvantages of each approach are identified based on computational speed and accuracy. The results are then compared with experimental data for velocity, temperature, major and minor species distribution to establish the computational accuracy of each approach. Together with the inclusion of modifications in the modeling framework and usage of detailed chemistry with FGM-LES, these results provide important insights into the simulation of hydrogen-blended methane flames.
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Mohamed, A. Abd El-Sabor, Amrit Bikram Sahu, Snehasish Panigrahy, Gilles Bourque, and Henry Curran. "The Ignition of C1–C7 Natural Gas Blends and the Effect of Hydrogen Addition in the Low and High Temperature Regimes." In ASME Turbo Expo 2022: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/gt2022-82305.
Full textAbstract:
Abstract New ignition delay time (IDT) measurements for two natural gas (NG) blends composed of C1 – C7 n-alkanes, NG6 (C1:60.625%, C2:20%, C3:10%, C4:5%, nC5:2.5%, nC6:1.25%, nC7:0.625%) and NG7 (C1:72.635%, C2:10%, C3:6.667%, C4:4.444%, nC5:2.965%, nC6:1.976%, nC7:1.317%) by volume with methane as the major component are presented. The measurements were recorded using a high-pressure shock tube (HPST) for stoichiometric fuel in air mixtures at reflected shock pressures (p5) of 20–30 bar and at temperatures (T5) of 987–1420 K. The current results together with rapid compression machine (RCM) measurements in the literature show that higher concentrations of the higher n-alkanes (C4 – C7) ∼1.327% in the NG7 blend compared to the NG6 blend result in the ignition for NG7 being almost a factor of two faster than NG6 at compressed temperatures of (TC) ≤ 1000 K. This is due to the low temperature chain branching reactions that occur for higher alkane oxidation kinetics in this temperature range. On the contrary, at TC > 1000 K, NG6 exhibits ∼20% faster ignition than NG7 primarily because about 12% of the methane in the NG7 blend is primarily replaced by ethane (∼10%) in NG6, which is significantly more reactive than methane at these higher temperatures. The performance of NUIGMech1.2 in simulating these data is assessed and it can reproduce the experiments within 20% for all the conditions considered in the study. We also investigate the effect of hydrogen addition to the auto-ignition of these NG blends using NUIGMech1.2 which has been validated against the existing literature for natural gas/hydrogen blends. The results demonstrate that hydrogen addition has both an inhibiting and promoting effect in the low- and high-temperatures regime, respectively. Sensitivity analyses of the hydrogen/NG mixtures are performed to understand the underlying kinetics controlling these opposite ignition effects. At low temperatures, H-atom abstraction by ȮH radicals from C3 and larger fuels are the key chain-branching reactions consuming the fuel and providing the necessary fuel radicals which undergo low temperature chemistry (LTC) leading to ignition. However, with the addition of hydrogen to the fuel mixture, the competition for ȮH radicals by H2 via the reaction H2+ȮH↔Ḣ+H2O reduces the progress of the LTC of the higher hydrocarbon fuels thereby inhibiting ignition. At higher temperatures, since Ḣ+O2↔Ö+ȮH is the most sensitive reaction promoting reactivity, the higher concentrations of H2 in the fuel mixture leads to higher Ḣ atom concentrations leading to faster ignition due to an enhanced rate of the Ḣ+O2↔Ö+ȮH reaction.
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Gülder, Ö. L., B. Glavinčevski, and M. F. Baksh. "Fuel Molecular Structure and Flame Temperature Effects on Soot Formation in Gas Turbine Combustors." In ASME 1989 International Gas Turbine and Aeroengine Congress and Exposition. American Society of Mechanical Engineers, 1989. http://dx.doi.org/10.1115/89-gt-288.
Full textAbstract:
A systematic study of soot formation along the centerlines of axisymmetric laminar diffusion flames of a large number of liquid hydrocarbons, hydrocarbon blends, and aviation turbine and diesel fuels were made. Measurements of the attenuation of a laser beam across the flame diameter were used to obtain the soot volume fraction, assuming Rayleigh extinction. Two sets of hydrocarbon blends were designed such that the molecular fuel composition varied considerably but the temperature fields in the flames were kept practically constant. Thus it was possible to separate the effects of molecular structure and the flame temperature on soot formation. It was quantitatively shown that the smoke point height is a lumped measure of fuel molecular constitution. The developed empirical relationship between soot volume fractions and fuel smoke point and hydrogen to carbon ratio was applied to five different combustor radiation data, and good agreement was obtained.