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PSE: a Fortran program for modeling well-stirred reactors
Abstract
In this report the set of algebraic equations describing the perfectly stirred reactor is described first. Then the time-dependent equations are presented; unlike the algebraic equations the transient equations can be solved without such a good initial estimate. A method to calculate the first-order sensitivity coefficients of the mass fractions and temperature with respect to the rate constants is also given. The PSR code is not a stand-alone program; it is designed to be run in conjunction with the CHEMKIN program, which handles the chemical reaction mechanism and the thermodynamic properties. In addition, it uses a modified version of the STANJAN program to provide the possibility of using equilibrium compositions as initial solution estimates. The structure of the code is described in this report, and instructions for setting up and using the code are given. Finally, an example problem is presented. 18 refs., 2 figs.
... The kinetic model tends to represent the GC data fairly well, whereas those from Orbitrap analyses were scaled to the GC mole fraction at the lowest oxidation temperature common to the two types of experiments (480 K), i.e., GC, FTIR, and HPLC-MS. The normalized rate of consumption analysis was performed with PSR [20] at 540 K and 660 K. It indicated that DBE is essentially consumed by H-atom abstraction by hydroxyl radicals at both temperatures. ...
... The present experiments were simulated using the PSR computer code [20]. The detailed kinetic reaction mechanism of Thion et al. [14] was used. ...
In the present study, we investigated the oxidation of 2500 ppm of di-n-butyl ether under fuel-rich conditions (φ = 2) at low temperatures (460–780 K), a residence time of 1 s, and 10 atm. The experiments were carried out in a fused silica jet-stirred reactor. Oxidation products were identified and quantified in gas samples by gas chromatography and Fourier transform infrared spectrometry. Samples were also trapped through bubbling in cool acetonitrile for high-pressure liquid chromatography (HPLC) analyses. 2,4-dinitro-phenylhydrazine was used to derivatize carbonyl products and distinguish them from other isomers. HPLC coupled to high resolution mass spectrometry (Orbitrap Q-Exactive®) allowed for the detection of oxygenated species never observed before, i.e., low-temperature oxidation products (C8H12O4,6, C8H16O3,5,7, and C8H18O2,5) and species that are more specific products of atmospheric oxidation, i.e., C16H34O4, C11H24O3, C11H22O3, and C10H22O3. Flow injection analyses indicated the presence of high molecular weight oxygenated products (m/z > 550). These results highlight the strong similitude in terms of classes of oxidation products of combustion and atmospheric oxidation, and through autoxidation processes. A kinetic modeling of the present experiments indicated some discrepancies with the present data
... Relatively few studies have reported 41 the formation of elusive low-temperature oxidation products, 42 e.g., fuel's hydroperoxides (ROOH), keto-hydroperoxides (KHPs) 43 [16-24] , and highly oxygenated molecules (HOMs). Such species 44 were recently observed in oxidation experiments involving a JSR 45 and Molecular beam-synchrotron-vacuum UV-Photoionization-TOF 46 MS and/or HESI-or APCI-Orbitrap® (heated electrospray ioniza- 47 tion, atmospheric pressure chemical ionization), conducted for 48 a range of fuels [15 , 25-34] . Beside the autoxidation route con- 49 sidered in combustion yielding ketohydroperoxides, i.e., fuel Table 1 gives the experimental conditions. ...
... Simulations were conducted using PSR [46] from the Chemkin 149 II package [47] . Third O 2 addition reactions were presented in the 150 recent kinetic reaction mechanism proposed by Wang and Sarathy 151 [14] . ...
This study concerns the oxidation of n-hexane. It was conducted in continuous flow fused-silica jet-stirred reactor (JSR) at 10 atm and an equivalence ratio of 0.5. n-Hexane initial concentrations were (i) 2500 ppm with a mean residence time of 1.5 s and (ii) 1000 ppm with a mean residence time of 0.7 s; we operated in the cool-flame regime for temperatures ranging from 540 to 720 K and 530 to 800 K, respectively. Products were analyzed and quantified in the gas phase using gas chromatography (with flame ionization, thermal conductivity, and quadrupole mass spectrometry) and Fourier transform infrared spectrometry. Products of low-temperature oxidation were sampled in the JSR and trapped in acetonitrile for characterization using an Orbitrap Q-Exactive®. Flow injection analyses (FIA) and ultra-high pressure liquid chromatography (UHPLC) coupled with atmospheric pressure chemical ionization (APCI +/- modes)- high resolution mass spectrometry (HRMS) analyses were used to characterize hydroperoxides (C6H14O2), keto-hydroperoxides (C6H12O3, C3H6O3, C4H8O3, and C5H10O3), cyclic ethers (C6H12O), carboxylic acids (C2 to C6), ketones (C3 to C6), diones (C6H10O2), unsaturated ketones (C6H10O and C6H8O), unsaturated diones (C6H8O2), and highly oxygenated molecules (C6H12O4-8) produced by addition of three and four oxygen molecules on fuel's radicals. To confirm the presence of hydroxyl or hydroperoxyl groups in the oxidation products we used H/D exchange with D2O. 2,4-Dinitrophenylhydrazine (2,4-DNPH) derivatization was used to characterize and confirm the presence of different carbonyls which can be formed during the low temperature oxidation of n-hexane. An available kinetic reaction mechanism including 3rd O2 addition on fuel's radicals was used to simulate the formation of the presently detected keto-hydroperoxides (KHP) and highly oxygenated molecules (HOMs).
... The limitations of treating the recirculation zone as a continuously stirred tank reactor (CSTR) were tested by using available numerical combustion models (Glarborg et al., 1986) which examine the key parameters that control flame stability such as temperature, pressure, characteristic mixing (or residence time), and equivalence ratio, in addition to detailed inhibition chemistry. Attempts to model the extinction results using detailed kinetics in a CSTR code for stoichiometric methane/air mixtures plus inhibitor (1 9ioto 6 % agent by volume) yielded calculated residence times at extinction that were approximately two orders of magnitude smaller than the residence times (~) measured in the spray burner at extinction (Babushok et al., 1995b). ...
The engine nacelle in an aircraft encases the jet engine compressor, combustors, and turbine. A nacelle fire is typically a turbulent diffusion flame stabilized behind an obstruction in a moderately high speed air flow. The fuel source for a fire in the nacelle are leaking pipes carrying jet fuel or hydraulic fluid that can feed the fire either as a spray or in the form of a puddle or pool. Extinguishment occurs when a critical amount of agent is transported to the fire. After suppression of the fire, re-ignition can occur as fuel vapor makes contact with a hot metal surface or an electrical spark due to shorted wires. Because of its many positive attributes, halon 1301, or trifluorobromomethane (CF3Br), has been used as a fire extinguishing agent for protecting aircraft engine nacelles. As halon 1301 is replaced with possibly less effective suppressant, continued effective aircraft protection becomes a challenge. For this reason, organized guidance in the determination of the amount of replacement agent required for protection of engine nacelles over a range of operating conditions is needed. In this study, a series of experimental measurements were conducted and simple models were developed in an effort to provide an improved understanding of the
influence of various parameters on the processes controlling flame stability in engine nacelles. The knowledge gained is compiled into usable tools which may assist suppression system designers determine the mass and rate of agent injection required for engine nacelle fire suppression.
... The perfectly stirred reactor code [53] is applied for the chemical kinetics analysis and the transient solver is applied for all the experimental conditions. Simulations are performed isothermal conditions. ...
The NO-reburning by syngas is investigated by the jet-stirred reactor (JSR) experiments and kinetic modeling. The effects of CO 2 and methane are studied systematically under different reaction temperatures (T), equivalence ratios (Φ) and initial ratios of hydrogen to carbon monoxide (α). The kinetic modeling is carried out by the present modified detailed mechanism consisting of 151 species and 1408 reactions. The modeling results obtained using the present modified mechanism demonstrate the good consistency with experiments under most of the conditions. The CO 2 has significant inhibitory effect on the NO-reburning by syngas independent of variations in T, Φ and α. The maximum NO reduction efficiency is remarkably reduced than that under N 2 condition by at least 76%. The addition of 1000 ppm methane has been found to increase the NO-reburning by the syngas for CO 2 conditions by at least 243%. The effects of CO 2 and CH 4 must be considered for NO-reburning by syngas as the actual syngas contains CO 2 and methane. Considering the presence of CO 2 and CH 4 , the optimal condition to maximize the NO reduction efficiency is T ≈ 1150 K, Φ ≈ 1.67 and α ≈ 1. The mechanism under this optimal condition is determinate by pathway and sensitivity analyses. The critical reactions for NO-reburning by syngas in the presence of CO 2 and CH 4 are identified, which are important for future mechanism development and application of NO-reburning by syngas.
... Typical perfectly stirred reactor (PSR) calculations solve the following ordinary differential equations (ODEs) for species (Glarborg et al., 1986): ...
Bioethanol has been considered as a more sustainable alternative for fossil fuels, and it has been used as a drop-in fuel mixture. In this paper, the autoxidation properties of real kerosene as well as single, binary and ternary surrogates with the presence of ethanol are investigated for the first time. A simplified python code is proposed to predict the pressure drop of the PetroOXY method that was used for assessing the fuel autoxidation properties. The experimental results show that the addition of an ethanol concentration reduces the induction period of real kerosene while increasing that of surrogate mixtures. Also, the maximum pressure during the PetroOXY test increases with the increase of ethanol concentration. The model is able to predict the induction period of ethanol accurately by employing an automated reaction mechanism generator. A strategy to increase the autoxidation stability of ethanol by adding 1 g/L antioxidant has been evaluated. The efficiency of the antioxidants for ethanol is in the following order: PY > Decalin > DTBP > Tetralin > BHT > MTBP > BHA > TBHQ > PG.
... In our study, pre-exponential factor of elementary steps are calculated by methods derivate from Benson's techniques [46] whereas activation energies are chosen in first approximation by analogy with reactions in gas phase. Simulations were performed using the Chemkin® and Surface Chem-kin® software packages in a CSTR reactor [47,48]. The simulations were performed by simultaneously compiling the homogeneous and the heterogeneous sub-mechanisms so that the possible coupling could be taken into account. ...
The oxidative coupling (OCM) and the partial catalytic oxidation (POM) of methane as well as the homogeneous oxidation of methane (HOM) differ only in the ratio CH4/O2 used and of course in the use of a catalyst. It can therefore be considered that their overall reaction mechanism should be the same with elementary reactions of varying importance depending on the type of oxidation reaction studied. We have therefore tried to represent the results obtained during the experimental study of OCM and POM over La2O3 and that of the oxidation of methane in gas phase from a single mechanism. At high temperature, OCM and POM are catalytic reactions but their reaction mechanisms are very complex because the surface reactions are coupled to reactions in gas phase by the intermediary of radicals, so both homogeneous and heterogeneous mechanisms occur at the same time. In this work, the development and the validation of a hetero-homogeneous mechanism is proposed for the three reactions. This mechanism is based on elementary steps at the catalyst surface and elementary steps in gas phase for a large range of temperature (973 K–1173 K) and residence time (0.7 s–5.5 s).
The thermo- or thermo-catalytic decomposition of methane, resulting in the concomitant production of CO2-neutral turquoise hydrogen and solid carbon is gaining importance as a technology capable of fostering the decarbonization of the chemical and energy industries. Methane pyrolysis is an intrinsically multiscale and multiphase process where the gas phase cracking is accompanied by the interactions with the carbon fragments and/or the catalyst surface. To achieve a fundamental understanding, it is required to develop modeling techniques capable of accounting for the complex fluid dynamics behavior and the mass/heat transfer along with the description of the homogeneous and heterogeneous chemistry. Such modeling approaches contribute to the interpretation of the experiments and provide in-depth insights into the reactor behavior, resulting in the rational design of the reactors during process development. This chapter provides an in-depth and up-to-date review of the different modeling approaches that have been adopted to couple the transport phenomena with reaction kinetics in the methane cracking reactors for the production of turquoise hydrogen. Different modeling strategies with growing levels of complexity (1D, 2D, homogeneous, heterogeneous, multiphase, CFD) are analyzed in the context of non-catalytic (tubular, stirred, plasma, molten media) and catalytic (chemical vapor deposition, fluidized bed, catalytic molten media) reactor configurations. The key features of the modeling approaches together with their assumptions, prediction capabilities and possible disadvantages are critically discussed.
The development of clean, sustainable energy systems is one of the pre-eminent issues of our time. Most projections indicate that combustion-based energy conversion systems will continue to be the predominant approach for the majority of our energy usage, and gas turbines will continue to be important combustion-based energy conversion devices for many decades to come, used for aircraft propulsion, ground-based power generation, and mechanical-drive applications. This book compiles the key scientific and technological knowledge associated with gas turbine emissions into a single authoritative source. The book has three sections: the first section reviews major issues with gas turbine combustion, including design approaches and constraints, within the context of emissions. The second section addresses fundamental issues associated with pollutant formation, modeling, and prediction. The third section features case studies from manufacturers and technology developers, emphasizing the system-level and practical issues that must be addressed in developing different types of gas turbines that emit pollutants at acceptable levels.
Detonation properties of methane and natural gas were studied using ZND simulations and detonation limit experiments. The experiments were performed in two tube sizes, 32 mm and 6.4 mm in inner diameter over a range of initial pressures (between 3.4 kPa and 35 kPa) and with stoichiometric fuel-oxygen compositions. The fuels considered are high purity methane, high purity methane with dopant ozone, a real natural gas, and a family of natural gas surrogates. The natural gas surrogates were developed based on North American natural gas composition variations and designed to capture the expected mean and variance of fundamental combustion properties of natural gases. All natural gases tested in this work show a substantially smaller detonation induction length (about 40%) and lower detonation pressure limit (30% in terms of limiting pressure) than high purity methane. The ozonated methane at 3000 PPMv of ozone doping performed similarly to the natural gases. Overall, the results suggest that in methane-based mixtures, a smaller induction length correlates with a more predictable detonation behavior as evidenced by a lower detonation pressure limit. As such, natural gases are expected to have a wider operating range when used as a fuel for detonation-based engines. As importantly, induction length calculation results reveal that the variability in detonation and combustion behaviors resultant from composition variability is expected to be similar between natural gases and commercial methane. Finally, the results suggest that for safety-related studies, neat methane is a poor surrogate for studying natural gas explosions.
Global warming caused by the use of fossil fuels is a common concern of the world today. It is of practical importance to conduct in-depth fundamental research and optimal design for modern engine combustors through high-fidelity computational fluid dynamics (CFD), so as to achieve energy conservation and emission reduction. However, complex hydrocarbon chemistry, an indispensable component for predictive modeling, is computationally demanding. Its application in simulation-based design optimization, although desirable, is quite limited. To address this challenge, we propose a methodology for representing complex chemistry with artificial neural networks (ANNs), which are trained with a comprehensive sample dataset generated by the Latin hypercube sampling (LHS) method. With a given chemical kinetic mechanism, the thermochemical sample data is able to cover the whole accessible pressure/temperature/species space in various turbulent flames. The ANN-based model consists of two different layers: the self-organizing map (SOM) and the back-propagation neural network (BPNN). The methodology is demonstrated to represent a 30-species methane chemical mechanism. The obtained ANN model is applied to simulate both a non-premixed turbulent flame (DLR_A) and a partially premixed turbulent flame (Flame D) to validate its applicability for different flames. Results show that the ANN-based chemical kinetics can reduce the computational cost by about two orders of magnitude without loss of accuracy. The proposed methodology can successfully construct an ANN-based chemical mechanism with significant efficiency gain and a broad scope of applicability, and thus holds a great potential for complex hydrocarbon fuels.
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