scholarly journals Establishment and Validation of a Two-Component Surrogate Fuel Chemical Kinetic Skeletal Model for Fischer–Tropsch Fuel Synthesized from Coal

Energies ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1168
Author(s):  
Ruiqing Liu ◽  
Ruiliang Zhang ◽  
Yizhuo Feng ◽  
Tiantian Yang
Keyword(s):  
Laminar Flame ◽  
Cetane Number ◽  
Component Composition ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Fischer Tropsch ◽  
Index Method ◽  
Premixed Laminar ◽  
Surrogate Fuel ◽  
Skeletal Mechanism

Fischer–Tropsch (F–T) fuel, synthesized from coal-to-liquid (CTL), is an alternative fuel with clean and efficient characteristics. In this study, a surrogate fuel model was developed, including n-dodecane (n-C12H26) and iso-octane (i-C8H18), which represents the n-alkane and iso-alkane in F–T fuel synthesized from CTL, respectively. The proportions of the components in the surrogate fuel are determined by the characteristics of the practical fuel, including cetane number (CN), C/H ration and component composition. For the establishment of the skeletal mechanism model, firstly, based on a two-step direct relationship graph (DRG) and the computational singular perturbation (CSP) importance index method, a reduced model of n-dodecane was developed involving 159 species and 399 reactions, while the detailed n-dodecane mechanism consists of 1279 species and 5056 reactions. Then, the n-dodecane skeletal mechanism was constructed based on a decoupling methodology, involving the skeletal C12 mechanism from the reduced mechanism, a C2-C3 sub mechanism and a detailed H2/CO/C1 sub mechanism. Finally, the skeletal mechanism for the F–T surrogate fuel was developed, including the n-dodecane skeletal mechanism and an iso-octane macromolecular skeletal mechanism. The final mechanism for the F–T diesel surrogate fuel consists of 169 species and 406 reactions. The n-dodecane skeletal mechanism and iso-octane skeletal mechanism were validated on various fundamental experiments, including the ignition delay in shock tubes, the primary species concentrations in jet-stirred reactors and the premixed laminar flame over wide operating conditions, which show great agreement between the predictions and measurements. Moreover, an F–T surrogate fuel mechanism was employed to simulate the combustion characteristics of an engine using computational fluid dynamics (CFD). The results show that the mechanism can predict the performance of F–T fuel combustion in engine accurately.

Validated F-T Fuel Surrogate Model for Simulation of Jet-Engine Combustion

2010 ◽  
Author(s):  
Chitralkumar V. Naik ◽  
Karthik V. Puduppakkam ◽  
Abhijit Modak ◽  
Cheng Wang ◽  
Ellen Meeks
Keyword(s):  
Laminar Flame ◽  
Laboratory Data ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Reduction Techniques ◽  
Auto Ignition ◽  
Wide Range ◽  
Fuel Behavior ◽  
Detailed Kinetics ◽  
Surrogate Fuel

Validated surrogate models have been developed for two Fisher-Tropsch (F-T) fuels. The models started with a systematic approach to determine an appropriate surrogate fuel composition specifically tailored for the two alternative jet-fuel samples. A detailed chemical kinetic mechanism has been assembled for these model surrogates starting from literature sources, and then improved to ensure self-consistency of the kinetics and thermodynamic data. This mechanism has been tested against fundamental laboratory data on auto-ignition times, laminar flame-speeds, extinction strain rates, and NOx emissions. Literature data used to validate the mechanism include both the individual surrogate-fuel components and actual F-T fuel samples where available. As part of the validation, simulations were performed for a wide variety of experimental configurations, as well as a wide range of temperatures and equivalence ratios for fuel/air mixtures. Comparison of predicted surrogate-fuel behavior against data on real F-T fuel behavior also show the effectiveness of the surrogate-matching approach and the accuracy of the detailed-kinetics mechanisms. The resulting validated mechanism has been also reduced through application of automated mechanism reduction techniques to provide progressively smaller mechanisms, with different degrees of accuracy, that are reasonable for use in CFD simulations employing detailed kinetics.

Influence of Radiation Reabsorption on Laminar Burning Velocity of Methane Premixed Flame Composed With Steam and Carbon Dioxide

2005 ◽  
Author(s):  
Takumi Ebara ◽  
Norihiko Iki ◽  
Sanyo Takahashi ◽  
Won-Hee Park
Keyword(s):  
Carbon Dioxide ◽  
Gas Turbine ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Chemical Kinetic ◽  
Laminar Burning Velocity ◽  
Premixed Laminar ◽  
Kinetic Calculations ◽  
Reforming Gas ◽  
Radiation Reabsorption

Replacing the Nitrogen with another kind of inert gas such as steam and Carbon dioxide is effective for both reducing NOx and enhancing system efficiency in gas turbine combustor. But the flame properties of such radiative mixture are complicated because of the third body effect and radiation reabsorption. So, we made detailed chemical kinetic calculations including the effect of radiation reabsorption to clarify the premixed laminar flame speed of such mixture as one of the most important properties for controlling the combustion. The concentrations of mixture are varied, and addition of other species such as Carbon monoxide and Hydrogen are also calculated to simulate the utilization of reforming gas and partially oxidized gas. And the pressure was varied up to 5.0 MPa to simulate the 1700 °C class combined gas turbine system. The results show remarkable incensement of laminar burning velocity by considering the radiation reabsorption. Laminar burning velocities were accelerated up to 150% in cases of Methane–Oxygen and steam or Carbon dioxide mixture. It was found that preheating of upstream-unburned mixture caused this acceleration. And the influence of radiation reabsorption was much larger in case of lower pressure.

Toward Machine Learned Highly Reduced Kinetic Models for Methane/Air Combustion

2021 ◽  
Author(s):  
Mark Kelly ◽  
Stephen Dooley ◽  
Gilles Bourque
Keyword(s):  
Fluid Dynamics ◽  
Computational Fluid Dynamics ◽  
Kinetic Models ◽  
Laminar Flame ◽  
Error Function ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Flux Analysis ◽  
Detailed Model ◽  
Computational Fluid Dynamics Cfd

Abstract Accurate low dimension chemical kinetic models for methane are an essential component in the design of efficient gas turbine combustors. Kinetic models coupled to computational fluid dynamics (CFD) and chemical reactor networks (CRN) provide quick and efficient ways to test the effect of operating conditions, fuel composition and combustor design compared to physical experiments. However, detailed chemical kinetic models are too computationally expensive for use in computational fluid dynamics (CFD). We propose a novel data orientated three-step methodology to produce compact kinetic models that replicate a target set of detailed model properties to a high fidelity. In the first step, a reduced kinetic model is obtained by removing all non-essential species from the NUIG18_17_C3 detailed model containing 118 species using path flux analysis (PFA). This reduced model is so small that it does not retain fidelity in calculations to the detailed model. Thus, it is numerically optimised to replicate the detailed model’s prediction in two rounds; First, to selected species (OH,H,CO and CH4) profiles in perfectly stirred reactor (PSR) simulations and then re-optimised to the detailed model’s prediction of the laminar flame speed. This is implemented by a purposely developed Machine Learned Optimisation of Chemical Kinetics (MLOCK) algorithm. The MLOCK algorithm systematically perturbs all three Arrhenius parameters for selected reactions and assesses the suitability of the new parameters through an objective error function which quantifies the error in the compact model’s calculation of the optimisation target. This strategy is demonstrated through the production of a 19 species and a 15 species compact model for methane/air combustion. Both compact models are validated across a range of 0D and 1D calculations across both lean and rich conditions and shows good agreement to the parent detailed mechanism. The 15 species model is shown to outperform the current state-of-art models in both accuracy and range of conditions the model is valid over.

Prediction of Premixed Laminar Flame Structure and Burning Velocity of Aviation Fuel-Air Mixtures

2001 ◽  
Author(s):  
A. G. Kyne ◽  
P. M. Patterson ◽  
M. Pourkashanian ◽  
C. W. Wilson ◽  
A. Williams
Keyword(s):  
Reaction Mechanism ◽  
Laminar Flame ◽  
Burning Velocity ◽  
Flame Structure ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Aviation Fuel ◽  
Measured Temperature ◽  
Premixed Laminar ◽  
Increasing Temperature

The structure of a rich burner stabilised kerosene/O2/N2 flame is predicted using a detailed chemical kinetic mechanism where the kerosene is represented by a mixture of n-decane and toluene. The chemical reaction mechanism, consisting of 440 reactions between 84 species, is capable of predicting the experimentally determined flame structure of Douté et al. (1995) with good success using the measured temperature profile as input. Sensitivity and reaction rate analyses are carried out to identify the most significant reactions and based on this the reaction mechanism was reduced to one with only 165 reactions without any loss of accuracy. Burning velocities of kerosene-air mixtures were also determined over an extensive range of equivalence ratios at atmospheric pressure. The initial temperature of the mixture was also varied and burning velocities were found to increase with increasing temperature. Burning velocities calculated using both the detailed and reduced mechanisms were essentially identical.

Development of a skeletal oxidation mechanism for Fischer–Tropsch diesel surrogate based on decoupling method and particle swarm optimization

2020 ◽  
Vol 234 (8) ◽  
pp. 1147-1160
Author(s):  
Wenkai Chen ◽  
Xiaoyuan Fang ◽  
Cheng Zhu ◽  
Xinqi Qiao ◽  
Dehao Ju
Keyword(s):  
Particle Swarm Optimization ◽  
High Efficiency ◽  
Laminar Flame ◽  
Particle Swarm ◽  
Oxidation Mechanism ◽  
Fischer Tropsch ◽  
Swarm Optimization ◽  
Decoupling Method ◽  
Cracking Process ◽  
Surrogate Fuel

As an alternative liquid fuel, Fischer–Tropsch (FT) diesel has received significant attentions due to its characteristics of high efficiency and low emission. In this study, a surrogate fuel containing iso-hexadecane and n-dodecane with a mole ratio of 0.16:0.84 is formulated for real FT diesel by mimicking its combustion-related physicochemical properties. Mechanisms of these two components are developed based on decoupling methodology: skeletal sub-mechanisms describing iso-hexadecane and n-dodecane cracking process are constructed and combined with a reduced C0–C4 core mechanism, and then the Arrhenius parameters of certain reactions are tuned by particle swarm optimization algorithm to improve prediction accuracy. The optimized mechanisms are validated against experimental results of ignition delays, species concentrations and laminar flame speeds for iso-hexadecane and n-dodecane, respectively. Finally, by merging all the sub-mechanisms mentioned above, a skeletal oxidation model for FT diesel surrogate including 73 species and 324 reactions is obtained and employed in 3D CFD simulations to validate the ignition behavior of FT diesel sprays in a constant-volume combustion vessel; the simulation results show good agreement with experimental data.

Chemical Reactor Network Application to Emissions Prediction for Industial DLE Gas Turbine

2006 ◽  
Author(s):  
I. V. Novosselov ◽  
P. C. Malte ◽  
S. Yuan ◽  
R. Srinivasan ◽  
J. C. Y. Lee
Keyword(s):  
Gas Turbine ◽  
Chemical Reactor ◽  
Kinetic Mechanism ◽  
Chemical Kinetic ◽  
Operating Conditions ◽  
Reacting Flow ◽  
Ongoing Research ◽  
Chemical Reactor Network ◽  
Reaction Zones ◽  
Reactor Network

A chemical reactor network (CRN) is developed and applied to a dry low emissions (DLE) industrial gas turbine combustor with the purpose of predicting exhaust emissions. The development of the CRN model is guided by reacting flow computational fluid dynamics (CFD) using the University of Washington (UW) eight-step global mechanism. The network consists of 31 chemical reactor elements representing the different flow and reaction zones of the combustor. The CRN is exercised for full load operating conditions with variable pilot flows ranging from 35% to 200% of the neutral pilot. The NOpilot. The NOx and the CO emissions are predicted using the full GRI 3.0 chemical kinetic mechanism in the CRN. The CRN results closely match the actual engine test rig emissions output. Additional work is ongoing and the results from this ongoing research will be presented in future publications.

Laminar flame speed correlations for methane, ethane, propane and their mixtures, and natural gas and gasoline for spark-ignition engine simulations

2017 ◽  
Vol 18 (9) ◽  
pp. 951-970 ◽  
Author(s):  
Riccardo Amirante ◽  
Elia Distaso ◽  
Paolo Tamburrano ◽  
Rolf D Reitz
Keyword(s):  
Natural Gas ◽  
Laminar Flame ◽  
Spark Ignition ◽  
Flame Speed ◽  
Operating Conditions ◽  
Spark Ignition Engine ◽  
Computational Time ◽  
Laminar Flame Speed ◽  
Spark Ignition Engines ◽  
Empirical Correlations

The laminar flame speed plays an important role in spark-ignition engines, as well as in many other combustion applications, such as in designing burners and predicting explosions. For this reason, it has been object of extensive research. Analytical correlations that allow it to be calculated have been developed and are used in engine simulations. They are usually preferred to detailed chemical kinetic models for saving computational time. Therefore, an accurate as possible formulation for such expressions is needed for successful simulations. However, many previous empirical correlations have been based on a limited set of experimental measurements, which have been often carried out over a limited range of operating conditions. Thus, it can result in low accuracy and usability. In this study, measurements of laminar flame speeds obtained by several workers are collected, compared and critically analyzed with the aim to develop more accurate empirical correlations for laminar flame speeds as a function of equivalence ratio and unburned mixture temperature and pressure over a wide range of operating conditions, namely [Formula: see text], [Formula: see text] and [Formula: see text]. The purpose is to provide simple and workable expressions for modeling the laminar flame speed of practical fuels used in spark-ignition engines. Pure compounds, such as methane and propane and binary mixtures of methane/ethane and methane/propane, as well as more complex fuels including natural gas and gasoline, are considered. A comparison with available empirical correlations in the literature is also provided.

scholarly journals Emissions and In-Cylinder Combustion Characteristics of Fischer-Tropsch and Conventional Diesel Fuels in a Modern CI Engine

2005 ◽  
Author(s):  
Alexander G. Sappok ◽  
Jeremy T. Llaniguez ◽  
Joseph Acar ◽  
Victor W. Wong
Keyword(s):  
Combustion Characteristics ◽  
Operating Conditions ◽  
Fuel Properties ◽  
Emissions Reduction ◽  
Cylinder Pressure ◽  
Fischer Tropsch ◽  
Diesel Fuels ◽  
Ultra Low Sulfur Diesel ◽  
Low Sulfur ◽  
Detailed Chemical

Derived from natural gas, coal, and even biomass Fischer-Tropsch (F-T) diesel fuels have a number of very desirable properties. The potential for emissions reduction with F-T diesel fuels in laboratory engine tests and on-road vehicle tests is well documented. While a number of chemical and physical characteristics of F-T fuels have been attributed to the observed reduction in emissions, the actual effects of both the fuel properties and in-cylinder combustion characteristics in modern diesel engines are still not well understood. In this study a 2002, six-cylinder, 5.9 liter, Cummins ISB 300 diesel engine, outfitted with an in-cylinder pressure transducer. was subjected to a subset of the Euro III 13-mode test cycle under steady-state operating conditions. Emissions and in-cylinder pressure measurements were conducted for neat F-T diesel, low sulfur diesel (LSD), ultra-low sulfur diesel (ULSD), and a blend of FT/LSD. In addition, a detailed chemical analysis of the fuels was carried out. The differences in the measured combustion characteristics and fuel properties were compared to the emissions variations between the fuels studied, and an explanation for the observed emissions behavior of the fuels was developed.

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