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Combustion and Flame
Volume 55, Issue 2,
, Pages 213-224
A detailed chemical kinetic reaction mechanism for the combustion of propane is presented and discussed. The mechanism consists of 27 chemical species and 83 elementary chemical reactions. Ignition and combustion data as determined in shock tube studies were used to evaluate the mechanism. Numerical simulation of the shock tube experiments showed that the kinetic behavior predicted by the mechanism for stoichiometric mixtures is in good agreement with the experimental results over the entire temperature range examined (1150–2600K). Sensitivity and theoretical studies carried out using the mechanism revealed that hydrocarbon reactions which are involved in the formation of the HO2 radical and the H2O2 molecule are very important in the mechanism and that the observed nonlinear behavior of ignition delay time with decreasing temperature can be interpreted in terms of the increased importance of the HO2 and H2O2 reactions at the lower temperatures.
- M.W. Slack
- W.C. Gardiner et al.
- G.L. Schott
- C.J. Jachimowski
- A.M. Dean et al.
- W.G. Browne et al.
- D.B. Olson et al.
- T.A. Brabbs et al.
- K. Tabayashi et al.
- R. Hartig et al.
NASA Technical Note D-8501
NASA Technical Paper 1794
J. Combust. Sci. Tech.
Ing. J. Chem. Kin.
J. Phys. Chem.
- Review of propane-air chemical kinetic mechanisms for a unique jet propulsion application
2020, Journal of the Energy Institute
Overall, this effort endeavored to determine one appropriate option for each of these three types of mechanisms. The same year Jachimowski published a mechanism for propane combustion intended for scramjet engines . The mechanism covered 83 chemical reactions involving 27 independent species and was validated with data on ignition and combustion of propane in shock tube studies from Burcat  and McLain  for temperatures between 1150 K and 2600 K.
A review of available propane-air chemical kinetic mechanisms was undertaken to determine how best to computationally model the combustion of propane and air at standard sea level conditions inside a unique ramjet engine. The included review comprises a set of 35 distinct mechanisms covering more than 30 years of work intended to model different aspects of propane-air chemistry. A selection of the available mechanisms was compared using a calibrated and validated zero-dimensional constant volume simulation with mixture ignition delay as the primary metric. The most accurate version across a range of equivalence ratios and temperatures was the San Diego mechanism due to its continual evolution through the adjustment of the reactions forming hydroxyl radicals to match ignition data. Subsequently, a reduced form of this mechanism was generated for three-dimensional Computational Fluid Dynamics (CFD) simulations by removing reactions that did not affect the ignition delay at the 1ms level. A one-dimensional variable property reacting flow shock tube simulation illustrated that this reduced mechanism did lose some accuracy in predicting the ignition delay for a unique set of data. However, it worked effectively in conjunction with the CFD model to predict the unique operational characteristics of the acoustically-pressurized ramjet engine.
- Lift-off flames of propane under a variety of co-flow conditions
2019, Chemical Engineering and Processing - Process Intensification
This study aimed at understanding the effects of co-flow condition on lift-off characteristics of the propane jet flame. A co-flow burner system was used to provide free jet condition, air co-flow condition and vitiated co-flow condition. In vitiated co-flow, methane was the co-flow fuel, and the co-flow equivalence ratios of methane/air mixtures changed from 0.5 to 0.7. On the basis of the results, the flame issuing into air-co-flow showed a higher lift-off height compared to the flame not issuing into a co-flow (i.e. free jet condition), with a faster increment rate simultaneously. In the vitiated co-flow condition, a conversion of lift-off height changing tendency was observed with the increment of flow rate and equivalence ratio of the co-flow. As the cases remained the same equivalence ratio, the cases with lower co-flow rates showed higher lift-off heights in the early combustion period. The lift-off height increased with the equivalence ratio in the cases with low co-flow rate, however, it decreased at high co-flow rate. It could be observed in the captured images that the ignition process was accelerated with the increment of equivalence ratio and co-flow rate.
- High-pressure oxidation of propane
2019, Proceedings of the Combustion Institute
Several detailed chemical kinetic models have been developed and evaluated for propane oxidation, e.g., [17–21]. The models developed by Jachimowski , Frenklach and Bornside , Dagaut et al. , and Koert et al.  were evaluated at a maximum pressure of 15 atm. Qin et al.  optimized a detailed chemical kinetic model against ignition delays at P < 5 atm and flame data at atmospheric pressure.
The oxidation properties of propane have been investigated by conducting experiments in a laminar flow reactor at a pressure of 100 bar and temperatures of 500–900K. The onset temperature for reaction increased from 625K under oxidizing conditions to 725K under reducing conditions. A chemical kinetic model for high pressure propane oxidation was established, with particular emphasis on the peroxide chemistry. The rate constant for the important abstraction reaction C3H8 + HO2 was calculated theoretically. Modeling predictions were in satisfactory agreement with the present data as well as shock tube data (6–61bar) and flame speeds (1–5bar) from literature.
- Thermodynamic equilibrium analysis of combined dry and steam reforming of propane for thermochemical waste-heat recuperation
2017, International Journal of Hydrogen Energy
The thermochemical waste-heat recuperation is one for perspective way of increasing the energy efficiency of the fuel-consuming equipment. In this paper, the thermochemical waste-heat recuperation (TCR) by combined steam-dry propane reforming is described. To understand the influence of technological parameter such as temperature and composition of inlet gas mixture on TCR efficiency, thermodynamic equilibrium analysis of combined steam-dry propane reforming was investigated by Gibbs free energy minimization method upon a wide range of temperature (600–1200K) and different feed compositions at atmospheric pressure. The carbon and methane formation was also calculated and shown. From a thermodynamic perspective, the TCR can be used for increasing energy efficiency at temperatures above 950K because in this range the maximum conversion rate is reached (from 1.22 to 1.30 for the different feed composition). Approximately 10mol of synthesis gas can be generated per mole of propane at the temperatures greater than 1000K. Furthermore, the propane conversion rate and yield of hydrogen are increased with the addition of extra steam to the feed stock. Also, undesirable carbon formation can be eliminated by adding steam to the feed. The thermodynamic equilibrium analysis was accomplished by IVTANTHERMO which is a process simulator for thermodynamic modeling of complex chemically reacting systems and several results were checked by Aspen-HYSYS.
- A compact skeletal mechanism of propane towards applications from NTC-affected ignition predictions to CFD-modeled diffusion flames: Comparisons with experiments
The study aims at proposing a skeletal mechanism of propane oxidation that describes low-temperature combustion and predicts major hydrocarbon product formation in nonpremixed flames. Utilizing a combination of a sensitivity analysis and path flux analysis, we refine and minimize a recently proposed detailed mechanism of UC San Diego (Prince et al., 2017) without empirical adjustments of rate constants for elementary reactions. The skeletal mechanism with 33 species and 122 reactions improves accuracy for autoignition calculations in the negative temperature coefficient region and its size is commensurate to numerical grids used in solutions of computational fluid dynamics with detailed kinetics. For the first time, the previously measured temperature, major products and non-fuel hydrocarbons in diffusion flames of propane associated with counterflow and coflow configurations are, respectively, verified by means of 1-D kinetic modeling and 2-D computational fluid dynamics. A comprehensive analysis of decomposition pathways connected with preserved and removed reactions provides a clear foundation for mechanism developers to build mechanisms of other alkane fuel oxidation. The rate of production analysis interprets how the experimentally measured propene and 1-butene are formed earlier than acetylene and propyne in the coflow flame. Moreover, the present skeletal mechanism, compared with published detailed mechanisms, features a significant reduction in computational cost.(Video) Chemical Kinetic Modeling for Combustion, Curran, Day 3, Part 1
- Mechanical behavior of a notched oxide/oxide ceramic matrix composite in combustion environment: Experiments and simulations
2015, Composite Structures
This combustion is complex and is not yet fully characterized . Propane (C3H8) has very similar combustion characteristics to JP-8 and has been used to simulate the combustion of aviation fuel [22,23]. The chemical byproducts of propane combustion, such as free radicals, are similar to those found in JP-8 combustion.
This paper is focused on understanding the role of combustive environment on thermal fatigue of Nextel™ 720/alumina CMCs. The role of pre-existing flaws in thermal monotonic and fatigue failure of the CMCs is also computationally and experimentally investigated. A notch (hole) was fabricated on the samples to study the effect of defects on the mechanical behavior of CMCs in combustion environment. Fatigue life in the combustion condition for notched samples was lower by an order of magnitude in comparison to the unnotched samples in combustion environment and notched samples in isothermal furnace results across the range of applied stress. The different fatigue performance is attributed to the thermal gradient stresses and increased rate of oxidation due to a high moisture level in the combustion rig test condition. The former will be further verified using finite element analysis and the latter from finite element analysis and microscopic analysis of the fracture surfaces.
Research articleCombustion characteristics of premixed propane/hydrogen/air in the micro-planar combustor with different channel-heights
Applied Energy, Volume 203, 2017, pp. 635-642
In order to improve the working performance and fuel adaptability of the micro-combustor, micro-planar combustors with different channel-heights are fabricated, and the three-dimensional calculation model is also built so as to study the basic characteristics of the blended propane/hydrogen combustion process. It is found that the hydrogen-addition method can overcome the shortcomings of propane flame instability under micro-scale conditions. When a small amount of hydrogen is added, the flame location could be fixed due to the stimulation of the important free radical like OH, thus obviously bringing the increase of mixture flammability range. The hydrogen-enriched fuel can further reduce the minimum flammable channel-height of propane. When the hydrogen addition ratio reaches 20%, a stable combustion will be achieved even in 1.5mm channel-height micro-combustor. Regardless of the 2.0mm or 2.5mm channel-height combustor, the effect of hydrogen addition will be better, and the flame location moves upstream gradually with the increase of hydrogen fraction. From the view of chemical energy utilization, the 2.0mm height combustor will be more suitable in the blended-fuel combustion mode, which is owing to the significant growth of the radiant energy output from the external wall.
Research articleAnalysis on discharge coefficients in FEM modeling of hybrid air journal bearings and experimental validation
Tribology International, Volume 119, 2018, pp. 549-558
Solving the Reynolds equation is an efficient method to simulate the performance of the hybrid air journal bearings, and the accuracy of the method is determined by discharge coefficients (Cd). The discharge coefficients in hybrid air journal bearings are different with those in flat and static air bearings due to the varied film thickness in the circumference and working condition in high speeds. Taking account of these effects, a new formulation on computing discharge coefficients is proposed on the basis of the previous research. Furthermore, the variations in the bearing load performance are investigated using the modified Cd and the associated FEM method, supported by well-designed experiments.
Research articleSimulation of Producer Gas Combustion in a Premixed Burner for Ceramic Firing Process(Video) Advances in Theoretical Chemical Kinetics for Combustion, Speaker: Stephen Klippenstein
Energy Procedia, Volume 138, 2017, pp. 622-627
Producer gas from biomass may be used to substitute liquefied petroleum gas in ceramic firing process. Numerical simulation offers a powerful tool that can assist in ceramic kiln design, optimization and scale up of the process, saving expensive pilot works. This study aims to simulate combustion of producer gas in a premixed burner in ceramic kiln based on computational fluid dynamics. The steady-state governing equations were solved using the SIMPLE algorithm and the effect of turbulence on the mean flow field was accounted for using the RANS k–ω model. The reaction mechanism was used for combustion of producer gas as the intermediate species. For geometrical model, a 3D model for the burner was developed while an axis-symmetric model for a combustion chamber was implemented to reduce computational costs. The present model was validated and refined using results from experiments. It was found that simulated results of flow and temperature patterns were qualitatively in similar agreement to experiments. For temperature profiles, mean differences between experiments and simulation were within 1.0-7.4%.
Research articleExperimental and numerical study of premixed propane/air combustion in the micro-planar combustor with a cross-plate insert
Applied Thermal Engineering, Volume 136, 2018, pp. 177-184
Over the past decade, the micro-thermophotovoltaic (MTPV) system has aroused widely public attention. Micro-combustor is an important part, which can determine the working performance of this micro-power generator. In this paper, experimental investigations as well as a three-dimensional CFD simulation have been carried out to study the performance of propane/air premixed combustion in a new kind of cross-plate micro-planar combustor. Benefited from the heat transfer enhancement by the setting up of cross-plate, the average wall temperature of the new combustor is increased by more than 90 K, which results in the growth of radiation efficiency. Besides, the blowout limit is apparently extended in the cross-plate combustor. Compared to the single-channel combustor, the blowout limit of propane/air in the cross-plate combustor can be raised by 0.4 m/s at equivalence ratio 0.7. It is also found that the cross-plate length can significantly affect the flame shape in the micro-channel and temperature distribution of the external wall. In contrast, the dimensionless plate length of 5/9 is suggested as the optimal structure parameter for the micro-combustor, which is due to the highest radiation efficiency.
Research articleExperimental study of the effect of CO2 on propane oxidation in a Jet Stirred Flow Reactor
Fuel, Volume 184, 2016, pp. 876-888
The use of advanced combustion technologies (MILD, oxy-fuel combustion) is among the most promising methods to reduce emission of pollutants, as the system working temperatures are enough low to boost the formation of several classes of pollutants. To access this temperature range, a significant dilution of reactants is required. At the same time, reactants have to be preheated to sustain the oxidation process. Such conditions are achieved by a strong recirculation of exhausted gases. Such a strategy implies that high contents of CO2 and/or H2O interact with the reactants oxidation chemistry. In order to characterize this aspect of the combustion processes under diluted conditions, experimental tests were carried out for propane/oxygen/nitrogen mixtures in presence of variable amounts of CO2 in a quartz Jet Stirred Flow Reactor (JSFR). Experiments were realized at atmospheric pressure, over the temperature range 720–1100K, from fuel lean to rich conditions and at a residence time of 0.5s. Temperature and species concentration measurements suggest that the oxidation of propane is significantly altered by CO2 in dependence of mixture inlet temperatures and equivalence ratios.
Numerical simulations pointed out that kinetic models are not able to correctly reproduce the experimental results. Further numerical analyses were performed to explore the interaction of CO2 with the oxidation chemistry of propane. Results suggested that such a species alters the main radical branching mechanisms, i.e. in termolecular reactions as a third body species with high collisional efficiency or directly participating in bimolecular reactions.
Research articleYet another kinetic mechanism for hydrogen combustion
Combustion and Flame, Volume 203, 2019, pp. 14-22
Recent suggestion by Burke and Klippenstein (2017) that chemically termolecular reactions H + O2 + R may significantly affect kinetic pathways under common combustion situations requires careful analysis, since, if included in contemporary kinetic mechanisms, these reactions affect global reactivity and calculated burning velocities of laminar premixed flames. In the view of their impact, a detailed kinetic scheme for hydrogen combustion was revisited to elucidate how to counterbalance enhanced chain termination caused by chemically termolecular reactions in attempt to keep or improve model performance. First, recent experimental and theoretical kinetic studies of hydrogen reactions were analyzed. In the new mechanism four reactions were introduced and three rate constants were updated. These changes, however, significantly reduce calculated burning velocities of H2 + air flames as compared to experimental data and earlier model predictions with the major impact from chemically termolecular reactions. It was then found that implementation of the new theoretical transport database developed by Jasper et al. (2014) significantly improves the performance of the updated kinetic model. The new kinetic mechanism for hydrogen combustion which includes updated kinetics and new transport properties was found in good agreement with the consistent dataset of the burning velocity measurements for hydrogen flames obtained using the heat flux method at atmospheric pressure for which the behavior of the previous model of the author was not satisfactory.
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