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Quarterly published in print and online "Inventi Impact: Combustion" publishes high quality unpublished as well as high impact pre-published research and reviews catering to the needs of researchers and professional engineers. The journal deals with multiple aspects of combustion including flame and fire research, flame radiation, chemical fuels and propellants, thermochemistry, atmospheric chemistry and combustion phenomena related to aircraft gas turbines, chemical rockets, ramjets, automotive engines and furnaces.
Two solid pyrolysis models are employed in a concurrent-flow flame spread model to compare the flame structure and spreading characteristics. The first is a zeroth-order surface pyrolysis, and the second is a first-order in-depth pyrolysis. Comparisons are made for samples when the spread rate reaches a steady value and the flame reaches a constant length. The computed results show (1) the mass burning rate distributions at the solid surface are qualitatively different near the flame (pyrolysis base region), (2) the first-order pyrolysis model shows that the propagating flame leaves unburnt solid fuel, and (3) the flame length and spread rate dependence on sample thickness are different for the two cases....
The work presents comparisons of the flame stabilization characteristics of axisymmetric disk and 2D slender bluff-body burner\r\nconfigurations, operating with inlet mixture stratification, under ultralean conditions.Adouble cavity propane air premixer formed\r\nalong three concentric disks, supplied with a radial equivalence ratio gradient the afterbody disk recirculation, where the first flame\r\nconfiguration is stabilized. Planar fuel injection along the center plane of the leading face of a slender square cylinder against the\r\napproach cross-flow results in a stratified flame configuration stabilized alongside the wake formation region in the second setup.\r\nMeasurements of velocities, temperatures, OH* and CH* chemiluminescence, local extinction criteria, and large-eddy simulations\r\nare employed to examine a range of ultralean and close to extinction flameconditions.Thevariations of the reacting front disposition\r\nwithin these diverse reacting wake topologies, the effect of the successive suppression of heat release on the near flame region\r\ncharacteristics, and the reemergence of large-scale vortical activity on approach to lean blowoff (LBO) are investigated. The crosscorrelation\r\nof the performance of these two popular flame holders that are at the opposite ends of current applications might\r\noffer helpful insights into more effective control measures for expanding the operational margin of a wider range of stabilization\r\nconfigurations....
Lignocellulosic biomass is a vital resource for providing clean future energy with a sustainable environment. Besides lignocellulosic\nresidues, nonlignocellulosic residues such as sewage sludge from industrial and municipal wastes are gained much\nattention due to its large quantities and ability to produce cheap and clean energy to potentially replace fossil fuels. These cheap\nand abundantly resources can reduce global warming owing to their less polluting nature. The low-quality biomass and high ash\ncontent of sewage sludge-based thermal conversion processes face several disadvantages towards its commercialization. Therefore,\nit is necessary to utilize these residues in combination with coal for improvement in energy conversion processes. As per author\ninformation, no concrete study is available to discuss the synergy and decomposition mechanism of residues blending. The\nobjective of this study is to present the state-of-the-art review based on the thermal coconversion of biomass/sewage sludge, coal/\nbiomass, and coal/sewage sludge blends through thermogravimetric analysis (TGA) to explore the synergistic effects of the\ncomposition, thermal conversion, and blending for bioenergy production. This paper will also contribute to detailing the\noperating conditions (heating rate, temperature, and residence time) of copyrolysis and cocombustion processes, properties, and\nchemical composition that may affect these processes and will provide a basis to improve the yield of biofuels from biomass/\nsewage sludge, coal/sewage sludge, and coal/biomass blends in thermal coconversion through thermogravimetric technique.\nFurthermore, the influencing factors and the possible decomposition mechanism are elaborated and discussed in detail. This study\nwill provide recent development and future prospects for cothermal conversion of biomass, sewage, coal, and their blends....
Dilution combustion has been widely utilized due to various merits, such as enhanced efficiency, fewer pollutants emissions, and
even a promising future in alleviating global warming. Diluents can be introduced through the oxidizer or fuel side to achieve the
desired combustion properties, and H2O and CO2 are the most common ones. A comprehensive comparison between the
different dilution methods still lacks understanding and optimizes the dilution combustion technologies. +is study numerically
compared the effects of H2O and CO2 dilution in the oxidizer or fuel stream on counterflow methane diffusion flames, emphasizing
NO formation kinetics. Results showed that the impact of different radiation heat transfer models on NO emissions
diminishes with increasing the dilution ratio. +e calculations of radiation heat transfer were treated in three ways: radiationneglected,
optically thin, and using a nongrey radiation model. When keeping the oxygen content and methane fraction constant,
CO2 dilution in the air-side has the most profound influence on NOreduction, and CO2 dilution in the fuel-side has the least.H2O
dilution showed a medium impact with a larger degree on air-side than that on fuel-side. To gain a deeper understanding of this
effect order, the contributions of different NO formation routes were quantified, and analyses were made based on the diluents’
chemical and thermal effects. It was found that the oxidizer-side dilution and fuel-side dilution affect the NO formation pathway
similarly. Still, the influence of H2O dilution on the NO formation pathway differs from that of CO2 dilution....
Ni catalysts supported on SiO2 are prepared via a facile combustion method. Both glycine\nfuel and ammonium nitrate combustion improver facilitate the formation of much smaller Ni\nnanoparticles, which give excellent activity and stability, as well as a syngas with a molar ratio\nof H2/CO of about 1:1 due to the minimal side reaction toward revserse water gas shift (RWGS) in\nCH4 dry reforming....
CO2 emissions from fossil fuel combustion have been considered as the most important driving factor of global climate change. A\ncomplete understanding of the rules of CO2 emissions is warranted inmodifying the climate change mitigation policy. The current\npaper advanced a new algorithm of parameter estimation for the logistic equation, which was used to simulate the trend of CO2\nemissions from fossil fuel combustion. The differential equation of the transformed logistic equation was used as the beginning\nof the parameter estimation. A discretization method was then designed to input the observed samples. After minimizing the\nresidual sum of squares and letting the summation of the residual be equal to 0, the estimated parameters were obtained. Finally,\nthis parameter estimation algorithm was applied to the carbon emissions in China to examine the simulation precision. The\nerror analysis indicators mean absolute percentage error (MAPE), median absolute percentage error (MdAPE), maximal absolute\npercentage error (MaxAPE), and geometric mean relative absolute error (GMRAE) all showed that the new algorithm was better\nthan the previous ones....
Erosive burning refers to the augmentation of propellant burning rate appears when the velocity of combustion gas flowing parallel to
the propellant surface is relatively high. Erosive burning can influence the total burning rate of propellant and performance of solid
rocket motors dramatically. There have been many different models to evaluate erosive burning rate for now. Yet, due to the
complication processes involving in propellant and solid rocket motor combustion, unknown constants often exist in these models.
To use these models, trial-and-error procedure must be implemented to determine the unknown constants firstly. This makes
many models difficult to estimate erosive burning before plenty of experiments. In this paper, a new erosive burning rate model is
proposed based on the assumption that the erosive burning rate is proportional to the heat flux at the propellant surface. With
entrance effect, roughness, and transpiration considered, convective heat transfer coefficient correlation proposed in recent years is
used to compute the heat flux. This allows the release of unknown constants, making the model universal and easy to implement.
The computational data of the model are compared with different experimental and computational data from different models.
Results show that good accuracy (10%) with experiments can be achieved by this model. It is concluded that the present model
could be used universally for erosive burning rate evaluation of propellant and performance prediction of solid rocket motor as well....
The performance of algebraic flame surface density (FSD) models has been assessed for flames with nonunity Lewis number (Le)\r\nin the thin reaction zones regime, using a direct numerical simulation (DNS) database of freely propagating turbulent premixed\r\nflames with Le ranging from 0.34 to 1.2. The focus is on algebraic FSD models based on a power-law approach, and the effects\r\nof Lewis number on the fractal dimension D and inner cut-off scale ?i have been studied in detail. It has been found that D is\r\nstrongly affected by Lewis number and increases significantly with decreasing Le. By contrast, ?i remains close to the laminar flame\r\nthermal thickness for all values of Le considered here. A parameterisation of D is proposed such that the effects of Lewis number\r\nare explicitly accounted for. The new parameterisation is used to propose a new algebraic model for FSD. The performance of the\r\nnew model is assessed with respect to results for the generalised FSD obtained from explicitly LES-filtered DNS data. It has been\r\nfound that the performance of the most existing models deteriorates with decreasing Lewis number, while the newly proposed\r\nmodel is found to perform as well or better than the most existing algebraic models for FSD....
Oxy-coal combustion is one of the more promising technologies currently under development for addressing the issues associated\nwith greenhouse gas emissions from coal-fired power plants. Oxy-coal combustion involves combusting the coal fuel in mixtures\nof pure oxygen and recycled flue gas (RFG) consisting of mainly carbon dioxide (CO2). As a consequence, many researchers and\npower plant designers have turned to CFD simulations for the study and design of new oxy-coal combustion power plants, as\nwell as refitting existing air-coal combustion facilities to oxy-coal combustion operations. While CFD is a powerful tool that can\nprovide a vast amount of information, the simulations themselves can be quite expensive in terms of computational resources and\ntime investment. As a remedy, a reduced order model (ROM) for oxy-coal combustion has been developed to supplement the CFD\nsimulations. With this model, it is possible to quickly estimate the average outlet temperature of combustion flue gases given a\nknown set of mass flow rates of fuel and oxidant entering the power plant boiler as well as determine the required reactor inlet mass\nflow rates for a desired outlet temperature. Several cases have been examined with this model.The results compare quite favorably\nto full CFD simulation results....
A robust fiber Bragg grating (FBG) hydrogen gas sensor for reliable multipoint-leakage monitoring has been developed. The\nsensing mechanism is based on shifts of center wavelength of the reflection spectra due to temperature change caused by\ncatalytic combustion heat. The sensitive film which consists of platinum-supported silica (Pt/SiO2) catalyst film was obtained\nusing sol-gel method. The precursor solution was composed of hexachloroplatinic acid and commercially available silica\nprecursor solution. The atom ratio of Si : Pt was fixed at 13 : 1. A small amount of this solution was dropped on the substrate\nand dried at room temperature. After that, the film was calcined at 500Ã?Â°C in air. These procedures were repeated and therefore\nthick hydrogen-sensitive films were obtained. The catalytic film obtained by 20-time coating on quartz glass substrate showed a\ntemperature change 75 K upon exposure to 3 vol.% H2. For realizing robust sensor device, this catalytic film was deposited and\nFBG portion was directly fixed on titanium substrate. The sensor device showed good performances enough to detect hydrogen\ngas in the concentration range below lower explosion limit at room temperature. The enhancement of the sensitivity was\nattributed to not only catalytic combustion heat but also related thermal strain....
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