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Burn rate (chemistry)

About: Burn rate (chemistry) is a research topic. Over the lifetime, 847 publications have been published within this topic receiving 8908 citations. The topic is also known as: Burning rate.


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Journal ArticleDOI
TL;DR: In this paper, the surface heterogeneity of a composite propellant is incorporated in a model of the propellant combustion process, explicitly including the oxidizer particle size distribution, and expressions for the mean, one-dimensional, propellant surface and flame temperatures are derived assuming planar regions of heat generation.
Abstract: The surface heterogeneity of a composite propellant is incorporated in a model of the propellant combustion process. This process is pictured as the sum of fuel pyrolysis, oxidizer decomposition, heterogeneous chemical reaction between the fuel and decomposed oxidizer in small fissures surrounding individual oxidizer particles, and gas phase combustion of all final decomposition products. Expressions for the burning rate and the rate of heat generation at the propellant surface and in the gas phase flame are formulated, explicitly including the oxidizer particle size distribution. Expressions for the mean, one-dimensional, propellant surface and flame temperatures are derived assuming planar regions of heat generation. A collected set of implicit, algebraic equations is solved numerically for the propellant burning rate, surface (and flame) temperatures for a variety of physical parameters. The burning rate is found to depend strongly on the oxidizer particle ignition delay at low pressures, and upon the position of the external flame at high pressures. The effect of the heterogeneous reaction on the burning rate is strongest at intermediate pressures. The results agree quite well with experimental data on the effect of pressure and oxidizer particle size on composite propellant burning rates, surface temperatures, and surface structure.

134 citations

Journal ArticleDOI
01 Jan 2005
TL;DR: In this paper, a detailed experimental study of the nine isomers of heptane has been performed in a rapid compression machine, where the role of molecular structure of the C 7 H 16 hydrocarbons on the rate of combustion of the various isomers has been determined.
Abstract: A detailed experimental study of the nine isomers of heptane has been performed in a rapid compression machine Our interest lies in determining the role of molecular structure of the C 7 H 16 hydrocarbons on the rate of combustion of the various isomers Ignition delay times were measured, and their dependence on the reaction conditions of temperature and pressure was studied, and in this way comparative reactivity profiles of the different isomers were obtained Stoichiometric fuel and ‘air’ mixtures were studied in each case, at compressed gas pressure of 10, 15, and 20 atm for the n -heptane study, and at 15 atm for all other isomers, in the compressed gas temperature range of 640–960 K Characteristic negative temperature coefficient behaviour was observed for each of the isomers The more branched isomeric forms of heptane exhibited reduced reactivity, which correlated with the research octane number In addition, the influence of fuel structure on burn rate was also studied It was found that, similar to overall reactivity, the burn rate decreased with increasing octane number

131 citations

Journal ArticleDOI
TL;DR: The results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.
Abstract: The aim was to identify relationships between combustion conditions, particle characteristics, and optical properties of fresh and photochemically processed emissions from biomass combustion. The combustion conditions included nominal and high burn rate operation and individual combustion phases from a conventional wood stove. Low temperature pyrolysis upon fuel addition resulted in "tar-ball" type particles dominated by organic aerosol with an absorption Angstro exponent (AAE) of 2.5−2.7 and estimated Brown Carbon contributions of 50−70% to absorption at the climate relevant aethalometer-wavelength (520 nm). High temper- ature combustion during the intermediate (flaming) phase was dominated by soot agglomerates with AAE 1.0−1.2 and 85− 100% of absorption at 520 nm attributed to Black Carbon. Intense photochemical processing of high burn rate flaming combustion emissions in an oxidation flow reactor led to strong formation of Secondary Organic Aerosol, with no or weak absorption. PM1 mass emission factors (mg/kg) of fresh emissions were about an order of magnitude higher for low temperature pyrolysis compared to high temperature combustion. However, emission factors describing the absorption cross section emitted per kg of fuel consumed (m 2 /kg) were of similar magnitude at 520 nm for the diverse combustion conditions investigated in this study. These results provide a link between biomass combustion conditions, emitted particle types, and their optical properties in fresh and processed plumes which can be of value for source apportionment and balanced mitigation of biomass combustion emissions from a climate and health perspective.

123 citations

Journal ArticleDOI
TL;DR: In this article, the effects of inert binder properties on composite solid propellant burning rate were investigated and defined for many binders of practical interest over a wide range of heating rates and pressures, in several environmental gases, with and without 10 percent ammonium perchlorate (AP) contained in the sample, and in some cases with catalysts.
Abstract: : The objective of this program was to investigate and define the effects of inert binder properties on composite solid propellant burning rate. Experimental pyrolysis data were obtained for many binders of practical interest over a wide range of heating rates and pressures, in several environmental gases, with and without 10-percent ammonium perchlorate (AP) contained in the sample, and in some cases with catalysts. These data were used to extract kinetics constants from Arrhenius plots, and heat of decomposition. In addition, motion pictures were taken of the pyrolyzing surface and gas samples were extracted for analysis. Pyrolysis kinetics varied between binders, but were found to be independent of pressure, the presence of AP, and the presence of burn rate catalysts; however, a chlorine gas environment had a material effect upon the results. All of the binders exhibited molten, boiling surfaces mingled with char, to varying degrees; the amount of char increased with AP present, and in chlorine. Relevant data were input to the Derr-Beckstead-Price combustion model in order to associate binder properties with known binder effects on burning rate. Although the effects were predictable, they stemmed from properties other than pyrolysis kinetics; however, the binder data as applied to the model revealed possible deficiencies in the model, which are discussed. It appears that the approach of combustion tailoring by binder modification would have to involve the gas phase combustion processes rather than surface pyrolysis. Therefore, future work concerning the role of binder should be directed toward the gas phase.

118 citations

Journal ArticleDOI
TL;DR: In this paper, a number of experimental techniques were developed for describing the characteristics of the CCPs as a function of the oxidizer particle size and pressure. But the results of these experiments were limited to the case of aluminized solid propellants.
Abstract: Experimental results are presented on the formation of condensed combustion products (CCPs) at the burning surface of aluminized solid propellants. A number of experimental techniques were developed for describing the characteristics of the CCPs as a function of the oxidizer particle size and pressure. The results of this investigation provide qualitative descriptions of the CCPs formed at the propellant burning surface as functions of oxidizer particle size and pressure. Nomenclature ak = oxidizing potential of gas mixture (mole share of oxidizing components in the mixture) D = diameter of agglomerate D43 = mass-medium diameter of agglomerates D AP = mass-medium diameter of ammonium perchlorate particles d = diameter of e ne oxide particle d HDO 43 = mass-medium diameter of e ne oxide particles Fm.D/ = mass function of agglomerate size distribution fm.D/ = mass function of agglomerate size distribution density fm.d/ = mass function of e ne oxide particle size distribution density P = pressure r = propellant burn rate T = temperature Zm = share of unburned metal in the agglomerates relative to the initial aluminum in the propellant Z a = share of initial metal in the propellant used to form the agglomerates as a whole Z HDO = share of initial metal in the propellant used to form the e ne oxide particles Z ox = share of initial metal in the propellant used to form oxide in the agglomerates ° = edge angle of wetting ´ = mass share of oxide in agglomerates

101 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202310
202220
202116
202015
201918
201811