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Combustion Temperature (combustion + temperature)

Distribution by Scientific Domains

Chemistry	72%

Selected Abstracts

Ways to Create New CHNO-Oxidizers for Stoichiometric Gas-Generating Compositions with Low Combustion Temperature

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 5 2007
David
Abstract The investigation is aimed to study the possibility of creation of new CHNO-oxidizers for smokeless gas-generating compositions for airbag inflators. For ensuring low amount of CO and nitrogen oxides in combustion products it is necessary to create stoichiometric compositions with a relatively low combustion temperature. Ways to create new oxidizers acceptable to this requirement are examined, mainly by introducing low-enthalpy oxygen-containing groups into the oxidizer molecule. Standard enthalpy of formation (,fH°) has been calculated for substances with unknown ,fH°, thermal stability has been qualitatively estimated, and combustion temperatures of stoichiometric compositions have been calculated. [source]

The effects of solid absorbents on the emission of trace elements, SO2, and NOx during coal combustion

INTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 12 2001
J. F. Cheng
Abstract The emission of toxic metals from the combustion of fossil fuels is an important global environmental issue. Solid absorbents can be used to control the emission of toxic trace elements from coal combustion. In this paper, limestone, CaSO4, bauxite, kaolinite and CaO are employed for this purpose and experiments are carried out in an electrically heated drop-tube furnace. The trace elements investigated are Pb, Cd, Cr and As. It is observed that the absorptive capacity is related to the qualities of the absorbents (type, amount and particle size) and the combustion temperature. The results also show that some absorbents can reduce SO2 emission simultaneously, but no influence on NOx emission. Copyright © 2001 John Wiley & Sons, Ltd. [source]

Anthropological and physicochemical investigation of the burnt remains of Tomb IX in the ,Sa Figu' hypogeal necropolis (Sassari, Italy) , Early Bronze Age

INTERNATIONAL JOURNAL OF OSTEOARCHAEOLOGY, Issue 2 2008
G. Piga
Abstract Excavations carried out in Tomb IX of the hypogeic necropolis of ,Sa Figu', near the village of Ittiri (Sassari, Italy), supplied burnt human bone remains and pottery unambiguously referred to the Early Bronze Age (characterised by the local culture of ,Bonnannaro'). Besides the anthropological study, we have investigated and evaluated the possibility of a funerary cremation practice in Sardinian pre-history, a subject that has previously not been considered from a scientific point of view. Making use of a calibration procedure based on X-ray diffraction (XRD) line-broadening analysis, related to the microstructural properties, it was possible to estimate the combustion temperature to which the fragmented bones were subjected. It was found that the studied bones reached temperatures varying from 400°C up to a maximum of 850°C. This spread of values suggested inhomogeneous combustion of the bones, which seems compatible with funerary cremation practices. Copyright © 2007 John Wiley & Sons, Ltd. [source]

A numerical study of combustion stability in emergency oxygen generators

AICHE JOURNAL, Issue 4 2006
Victor Diakov
Abstract Combustion in sodium chlorate based emergency oxygen generators is accompanied by significant oscillations of the product oxygen flow rate, which decrease the efficiency of these devices. Reactant melting and convective heat transfer from the generated gas are key steps in the process. In this work, the effect of reactant melting on filtration combustion front propagation stability in gas generating mixtures is investigated numerically. The formation of melting regions is demonstrated in cases with significant convective gas-to-core heat transfer. Numerical simulations exhibit the oscillatory behavior of oxygen generation. By decreasing the effective heat of reaction, reactant melting is detrimental to combustion front stability. The simulations show growth of pulsations with increasing reaction activation energy and decreasing convective heat transfer. A strong stabilization of front propagation is observed when combustion temperature reaches the melting point of reaction product. These results identify the important factors responsible for pulsating behavior of chemical oxygen generators. © 2005 American Institute of Chemical Engineers AIChE J, 2006 [source]

Synthesis of Ternary Titanium Aluminum Carbides Using Self-Propagating High-Temperature Synthesis Technique

JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2001
Micha, opaci
Different ternary carbide phases, namely Ti3AlC2, Ti3AlC, and Ti2AlC, were successfully synthesized in a self-sustaining regime. Direct reactions among elemental powders of titanium, aluminum, and carbon are strongly exothermic, and the resulting reaction products consist of binary carbides and they are partially molten. The use of TiAl, instead of elemental titanium and aluminum, significantly reduces the combustion temperature. As a result, ternary titanium aluminum carbide phases are formed. In addition, the combustion-synthesized products are not sintered and easy to deagglomerate. Reaction conditions and X-ray diffraction patterns of different ternary phases formed in a self-sustaining regime are presented. [source]

Ways to Create New CHNO-Oxidizers for Stoichiometric Gas-Generating Compositions with Low Combustion Temperature

Kinetic Regularities of the Heat Release for the Interaction of Some Organic Compounds with Ammonium Nitrate

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 6 2006

Abstract Ammonium nitrate (AN) is used as an oxidant in a series of systems with a wide spectrum of applications, from explosive compositions up to smokeless stoichiometric self-burning compositions with low combustion temperature. The knowledge of the thermal stability of such compositions is of great importance in using them in practice. In this work the research of kinetics of heat release in the interaction of AN with different organic compounds has been performed using the automatic differential calorimeter. [source]

Analysis of aromatic amines in cigarette smoke,

RAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 18 2003
Regina Stabbert
A method for the analysis of o -toluidine, o -anisidine, 2-naphthylamine, and 4-aminobiphenyl in cigarette mainstream smoke has been developed, which combines the sensitivity of their pentafluoropropionyl (PFP) derivatives in negative ion chemical ionization (NICI) mode with the selectivity of the gas chromatography/tandem mass spectrometry (GC/MS/MS) technique. The use of four deuterated analogues as internal standards along with the application of the standard addition method results in accurate and precise results; the interday precision for the aromatic amines was 3,10% and the accuracy ranged from 97,100%. This method was applied to two American-blend University of Kentucky reference cigarettes, eight American-blend market cigarettes, a bright (flue-cured) tobacco cigarette, and an electrically heated cigarette smoking system (EHCSS). For the American-blend cigarettes there was a linear correlation between aromatic amine yields and mainstream smoke ,tar' (,tar',=,total particulate matter , (nicotine,+,water)), whereas the bright tobacco cigarette and the EHCSS demonstrated significantly lower aromatic amine yields on an equal ,tar' basis. The results support the hypothesis that the nitrogen content of the tobacco, and above all the cigarette combustion temperature, are determining factors for the yields of aromatic amines in smoke. Copyright © 2003 John Wiley & Sons, Ltd. [source]

Catalytic Effects on Thermal Oxidation of Single-Walled Carbon Nanotubes by Alkali Metal Chlorides

CHEMCATCHEM, Issue 4 2010
Yuki Kobayashi
The walled is not enough: Alkali metal chlorides lower the combustion temperature of single-walled carbon nanotubes by more than 100,K. Unlike ordinary reactions of nanotubes, the oxidation reaction in the presence of these salts is independent of the tube diameter, defects, and the degree of bundling. Furthermore, they produce no additional soot upon combustion. [source]

Combustion Measurements of Fuel-Rich Aluminum and Molybdenum Oxide Nano-Composite Mixtures

PROPELLANTS, EXPLOSIVES, PYROTECHNICS, Issue 2 2010
Tim Bazyn
Abstract Fuel rich nano-composite powders of aluminum and molybdenum oxide were tested for ignition and combustion behind the incident and reflected shock waves in a shock tube. The powders consisted of approximately 10,,m particles, each of which contained Al and MoO3 mixed by mechanical alloying on the nano-scale. These powders were aluminum rich with composition ratios of 4,:,1, 8,:,1, and 16,:,1 Al,:,MoO3 by mass. Ignition tests were performed behind incident shocks for temperatures in the range of 900 to 1500,K. From these tests, ignition delay times were obtained, and some information on combustion duration was also derived. Samples were tested in air at 0.2,MPa, and compared against nano-Al, 2.7,,m Al, and 10,,m Al baselines. Ignition results for the baseline Al cases were as expected: 10,,m Al not igniting until 2000,K, 2,,m Al igniting down to ,1400,K, and n-Al igniting as low as 1150,K. The thermite samples showed considerable improvement in ignition characteristics. At the lowest temperature tested (900,K), both the 8,:,1 and 4,:,1 samples ignited within 250,,s. The 16,:,1 sample (94% Al) ignited down to 1050,K , which represents an improvement of roughly 1000,K over baseline Al with only a small energetic penalty. In all cases, the ignition delay increased as the amount of MoO3 in the composite was reduced. The 4,:,1 nano-composite material ignited as fast or faster than the n-Al samples. Ignition delay increased with decreasing temperature, as expected. Emission spectra and temperature data were also taken for all samples using high-speed pyrometry and time-integrated spectroscopy. In these cases, measurements were made behind the reflected shock using end-wall loading, though the conditions (temperature, pressure, and gas composition) were identical to the incident shock tests. Spectroscopy showed strong AlO features in all the samples, and the spectra fit well to an equilibrium temperature. Broadband, low resolution spectra were also fit to continuum, gray body temperatures. In general, the observed temperatures were reasonably close to 3500,K, which is similar to the combustion temperatures of pure aluminum under these conditions. [source]