Showing papers on "Combustion published in 1990"
TL;DR: A new combustion synthesis method, the glycine-nitrate process, has been used to prepare oxide ceramic powders, including substituted chromite and manganite powders of high quality.
992 citations
TL;DR: In this article, a four-step mechanism for the combustion of methane in air in non-premixed flames is obtained by making steady-state and partial equilibrium approximations for minor species.
754 citations
01 Jan 1990
TL;DR: In this paper, the authors present a survey of combustion and plasmas synthesis of high-temperature materials, including self-propagation hightemperature synthesis, modeling and numerical computation of a nonsteady SHS process, new modes of quasi-periodic burning in combustion synthesis, synthesis of intermetallic compounds, combustion synthesis of nickel aluminides, advanced ceramics via SHS, simultaneous combustion synthesis and densification of AlN, and oxide-carbide composites.
Abstract: Various papers on combustion and plasmas synthesis of high-temperature materials are presented. Individual topics addressed include: self-propagation high-temperature synthesis, modeling and numerical computation of a nonsteady SHS process, new modes of quasi-periodic burning in combustion synthesis, combustion synthesis of intermetallic compounds, combustion synthesis of nickel aluminides, advanced ceramics via SHS, simultaneous combustion synthesis and densification of AlN, combustion synthesis of oxide-carbide composites. Also discussed are: combustion synthesis in the Ti-C-Ni-Al systems, combustion synthesis dynamics modeling, shock-induced reaction synthesis-assisted processing of ceramics, shock consolidation of combustion-synthesized ceramics, thermal plasma synthesis ceramic powders and coatings, formation of refractory aerosol particles, silica particle formation using the counterflow diffusion flame burner, synthesis of Si, SiC, and Si3N4 powders under high number density conditions.
415 citations
TL;DR: The planar laser-induced fluorescence (PLIF) method as discussed by the authors allows simultaneous combustion measurements at more than 105 flowfield points, including high signal strength, ease of interpretation, and applicability for determining several flowfield variables (including concentration, temperature, velocity, pressure and density).
Abstract: An overview is provided of the planar laser-induced fluorescence (PLIF) method, which currently allows simultaneous combustion measurements at more than 105 flowfield points Important advantages of the method include its relatively high signal strength, ease of interpretation, and applicability for determining several flowfield variables (including concentration, temperature, velocity, pressure and density) Example results are shown for a turbulent non-premixed flame, a spray flame, a rod-stabilized premixed flame, and a diffusion flame from a fuel jet in cross-flow
307 citations
Patent•
04 May 1990
TL;DR: In this paper, a skin effect heater is added to a heat exchanger and combustion device for upgrading viscous crude oil feeds, which can be used to treat heavy crudes within a producing well.
Abstract: A separate heat source, such an a skin effect heater, is added to a subterranean heat exchanger and oxygen combustion device for upgrading viscous crude oil feeds. An insulated wire is integrated with combustion oxygen supply piping to form the skin effect heater operating in conjunction with the heat exchanger. The separately controlled heater output allows a reduction of the heat from the combustion device reduced quantities of combustion products. The improvement down-sizes or eliminates excess combustion product removal facilitates and also preheats the oxygen supply. The skin-effect heater and heat exchanger combination adds heat gradually and increases feed residence time at the desired upgrading temperature and pressure conditions. Alternative embodiments can be used to treat heavy crudes within a producing well.
256 citations
TL;DR: In this paper, the authors used a steam-cooled tube at the exit of a pilot scale furnace during combustion of bituminous coal to identify coal properties and combustion conditions with which one may anticipate fouling and slagging of superheaters in electric utility boilers.
208 citations
TL;DR: In this article, a char morphology system based on the physical and optical characteristics known to influence the burning of pulverized coal is outlined, and the proportions of different pyrolysis char types produced by any coal are shown to depend on coal rank, petrographic composition, maceral fusibility, and possibly ash content and composition.
207 citations
TL;DR: An overview on the development of hydrogen fueled internal combustion engines and ties together the recent efforts with the past achievements in this field is presented in this paper, where the causes of various undesirable combustion phenomena such as backfire, pre-ignition, knocking and rapid rate of pressure rise are discussed.
198 citations
Patent•
21 Mar 1990
TL;DR: In this article, the authors present methods of recovering energy materials, such as oil, shale oil or hydrocarbon gas, by providing limited combustion of these energy materials within an underground energy material reservoir and, consequently, thinning and mobilizing the energy materials such that their recovery is increased.
Abstract: The present invention relates to methods of recovering energy materials, such as oil, shale oil or hydrocarbon gas, by providing limited combustion of these energy materials within an underground energy material reservoir and, consequently, thinning and mobilizing the energy materials such that their recovery is increased. The methods involve the injection into a borehole of an water/oxygen slurry which releases oxygen gas as it flows into the reservoir and recovering, at a later time following in-situ combustion and/or reaction, an improved energy material yield from said borehole or adjacent borehole.
185 citations
TL;DR: In this article, the authors synthesize together the available information on both of these fronts to facilitate understanding of those coal conversion technologies where either or both of the phenomena may play an important role.
168 citations
TL;DR: In this paper, a low-frequency combustion instability of a flame burning in a duct has been successfully controlled by the unsteady addition of extra fuel, which reduced the peak in the pressure spectrum due to the combustion instability by some 12 dB.
Abstract: A low-frequency combustion instability of a flame burning in a duct has been successfully controlled by the unsteady addition of extra fuel. A suitably phased addition of only 3% more fuel reduces the peak in the pressure spectrum due to the combustion instability by some 12 dB. The acoustic energy in the 0-400 Hz bandwidth is reduced to 18% of its uncontrolled value. Since relatively little unsteady fuel is necessary, the mechanical power requirements of the controller are modest and the system is easy to implement.
TL;DR: In this article, the nitrogen isotope ratios of several organic and inorganic materials have been analyzed by a sealed-tube combustion method requiring on-line cryogenic purification and by a new sealed tube combustion technique using CaO for the quantitative removal of CO{sub 2} and water.
Abstract: The nitrogen isotope ratios of several organic and inorganic materials have been analyzed by a sealed-tube combustion method requiring on-line cryogenic purification and by a new sealed-tube combustion technique using CaO for the quantitative removal of CO{sub 2} and water. Samples purified cryogenically are enriched in {sup 15}N by an average of 0.11{per thousand} relative to samples prepared with CaO. The enriched values of samples purified cryogenically probably result from the larger amounts of residual contaminants in samples prepared without CaO. Because samples prepared with the CaO technique require no additional purification, the technique is ideal for use with multisample mass spectrometer inlet systems.
Book•
11 Feb 1990
TL;DR: In this article, the authors present a comprehensive overview of the history of combustion for gas turbines, including a discussion of recent developments in the literature. Each chapter includes references to relevant references.
Abstract: Introduction to Combustion for Gas Turbines. Gas Turbine Fuels (Includes Tables). Fuel Injectors. Combustion System Design. Recent Developments. Each Chapter Includes References. Index.
TL;DR: In this article, a fuel spray planar counterflow flame was modeled by means of a low-Mach-number boundary layer approach, and conditions for similarity in such a two-phase, particle-laden reacting boundary layer have been determined.
01 Jan 1990
TL;DR: The state-of-the-art results on combustion theory can be found in this article, where the authors present a review of combustion chemistry and measurement techniques, and discuss heterogeneous combustion and homogeneous combustion.
Abstract: This book presents recent research results on combustion theory. Contributors present the state of knowledge on flame properties. Includes a review of combustion chemistry and measurement techniques, and discusses heterogeneous combustion and homogeneous combustion.
TL;DR: In this paper, the chemical kinetic basis for the formation and destruction of by-products during the incineration of hazardous wastes was studied and the authors focused on the chlorinated organics since certain classes of such compounds are frequently detected in incinerator effluents.
Abstract: This paper is concerned with the chemical kinetic basis for the formation and destruction of by-products during the incineration of hazardous wastes. Special attention is focussed on the chlorinated organics since certain classes of such compounds are frequently detected in incinerator effluents. Our approach is to concentrate on single step elementary processes and to use the existing chemical kinetic data base for hydrocarbon combustion as a starting point. We begin by listing available thermodynamic and kinetic data bearing on the processes of importance during incineration. This information is then used to examine the possible reaction pathways. Although definitive results can only be obtained from detailed modeling, our analysis demonstrates the importance of the nature of the reaction mixture. An important variable is the ratio of hydrogen to chlorine and when this ratio is low, chlorination of unburnt hydrocarbons may be an important source of undesirable side products. It is expected that...
TL;DR: In this paper, high quality diamond with good crystallinity has been successfully synthesized on a substrate using an oxy-acetylene combustion flame in the atmosphere, and the deposition rate of transparent diamond depended strongly on substrate temperatures and the O2/C2H2 ratio.
Abstract: High‐quality diamond with good crystallinity has been successfully synthesized on a substrate using an oxy‐acetylene combustion flame in the atmosphere. The crystal grains under some conditions have good optical transparency. The deposition rate of transparent diamond depended strongly on substrate temperatures and the O2/C2H2 ratio and averaged ∼30 μm/h. The substrate temperature for the growth of optically transparent crystals was 500–750 °C, which is relatively low compared with other chemical vapor deposition methods. The optical transparency is attributed to the low defect densities in the crystals, as determined by transmission electron microscope, which results from the low substrate temperatures and moderate growth rates. Raman spectroscopy and x‐ray diffraction data on the synthesized crystals were comparable with that of natural diamond. The synthesis conditions and corresponding diamond quality as well as emission spectrum analysis of the combustion flame during diamond synthesis are described.
TL;DR: In this article, a numerical study of combustion and multimode heat transfer in porous radiant burners is performed using a one-dimensional conduction, convection, radiation, and premixed flame model.
TL;DR: In this article, a survey has shown that catalytic combustion can be successfully applied to various domestic and industrial fuel-burning devices for improving combustion efficiency and thermal NO x control, and that the fuel NO x yield can be decreased by the use of oxide catalysts rather than platinum ones, by low excess air operation, and by decreasing the combustion of fuels in a fluidized catalyst bed in catalytic heat generators.
Abstract: The present survey has shown that catalytic combustion can be successfully applied to various domestic and industrial fuel-burning devices for improving combustion efficiency and thermal NO x control. The investigation of kinetics of oxidation of nitrogen-containing compounds on solid catalysts has shown that the fuel NO x yield can be decreased by the use of oxide catalysts rather than platinum ones, by low excess air operation, and by decreasing the combustion of fuels in a fluidized catalyst bed in catalytic heat generators makes it possible to conduct technological processes at high fuel loads on a catalyst and at rather low temperatures in the combustion zone (770-1070 K) owing to the combination of heat evolution and heat removal in the same catalyst bed
TL;DR: In this paper, a second-law analysis of the combustion process in a diesel engine is presented for a single-zone model and expressions for availability and the availability balance are developed in detail from the energy and entropy balances and applied in a manner that allows the irreversibility due to combustion to be separated from that associated with heat transfer to the walls.
Abstract: A second-law analysis of the combustion process in a diesel engine is presented for a single-zone model. Expressions for availability and the availability balance are developed in detail from the energy and entropy balances and applied in a manner that allows the irreversibility due to combustion to be separated from that associated with heat transfer to the walls. Availability is divided into two components: thermomechanical and chemical availability. For the first time, chemical availability of the cylinder contents is dealt with rigorously, which allows for a correct determination of combustion irreversibilities. The analysis is applied in a parametric study of the effects of combustion timing, mass burning rate, and heat transfer rate on the irreversibility and system availability.
TL;DR: In this paper, eleven selected coals were burned under controlled conditions in a laboratory combustion furnace to determine the effect of coal type on the amount and composition of combustion generated inorganic submicron particles.
Abstract: Eleven selected coals were burned under controlled conditions in a laboratory combustion furnace to determine the effect of coal type on the amount and composition of combustion generated inorganic submicron particles. Significant differences in both the amount and composition of submicron particles were found between coals and particularly between rank of coals. In most cases, however, the extent to which an element appeared in the submicron fume could be correlated on the basis of its occurrence and distribution in the coals.
TL;DR: In this paper, a laminar diffusion flame has been studied experimentally by examining the characteristics of soot particles using laser light scattering, and the kinetics mechanisms of oxidation by O2 and OH have been analyzed.
TL;DR: In this paper, a mixture of soot and catalyst was placed in a flow reactor and a gas mixture containing 6% oxygen, 7% water and balance of nitrogen was led through it at a flow-rate of 90 l/h.
TL;DR: In this paper, the authors used the spark plug to detect the passage of flame 'front' in an internal combustion engine, where hot sport in the combustion chamber can cause fuel to ignite either before or after the normal spark ignition.
Abstract: Surface ignition in internal combustion engines – where hot sport in the combustion chamber can cause fuel to ignite either before or after the normal spark ignition – is both inefficient and harmful to the engine. Detection usually involves the engine being modified in some way, but a promising noninvasive technique is to use the spark plug to detect the passage of flame 'front'. This novel technique has been demonstrated recently in several research laboratories including that of M swain and colleagues at the University of Miami 1989 J. Phys. E: Sci. Instrum. 22 838).
TL;DR: In this article, the role of exothermic centers in the end-gas in initiating knocking combustion and subsequent knock damage to the combustion chamber walls is investigated experimentally and theoretically in an optical engine by high speed direct light photography and laser Schlieren filming.
Abstract: In this paper the nature of autoignition and knocking is investigated experimentally and theoretically in an optical engine by high speed direct light photography and laser Schlieren filming. Special emphasis is devoted experimentally and theoretically to the role of exothermic centers in the end-gas in initiating knocking combustion and subsequent knock damage to the combustion chamber walls. The optical engine is a modified single cylinder ported two stroke engine equipped with a large head window for unlimited access to both the entire combustion chamber and the ring crevice region. In some experiments the formation of exothermic centers was stimulated by microscopic aluminum particles that deposited on the mirrored piston surface. The data are analyzed by numerically modelling the transition from normal combustion to autoignition with a simplified 2D-code. This code models the interactions between exothermic centers, normal combustion and the resulting time dependent fields of pressure, temperature and gas velocities. The chemico-hydrodynamic coupling is especially strong near walls where compression heating by reflected pressure waves is most effective. Thus knocking combustion is preferentially stimulated near cylinder walls. The predominant occurrence of knock damage is in the ring crevice region where knocking combustion is associated with soot formation both in themore » crevice and the endgas region.« less
TL;DR: In this paper, the principal current and new thermal spray coating processes used for compressor, combustion chamber and turbine applications in aero engines are described with particular reference to high velocity combustion and plasma spraying techniques.
Abstract: The principal current and new thermal spray coating processes used for compressor, combustion chamber and turbine applications in aero engines are described with particular reference to high velocity combustion and plasma spraying techniques. The uses of coatings for wear and erosion resistance, oxidation and corrosion control, thermal barrier applications and gas path sealing (clearance control) are discussed.
TL;DR: In this article, a numerical analysis of combustion and multimode heat transfer in inert porous media is presented, where the influence of the flame location, the radiative properties of the porous material, the solid thermal conductivity, and stoichiometry on the flame speed and stability are determined using a one-dimensional conduction, convection, radiation and combustion model.
Abstract: This paper presents a numerical analysis of combustion and multimode heat transfer in inert porous media. The work is directly relevant to the understanding of premixed flame stabilization in porous radiant burners. The influence of the flame location, the radiative properties of the porous material, the solid thermal conductivity, and stoichiometry on the flame speed and stability are determined using a one-dimensional conduction, convection, radiation, and combustion model. The porous medium is allowed to emit, absorb, and scatter radiant energy, Non-local thermal equilibrium between the solid and gas is accounted for by introducing separate energy equations for the two phases. Heat release is described by a single-step, global reaction. The results indicate that stable combustion at elevated flame speeds can be maintained in two different spatial domains. Flame propagation near the edge of the porous layer is controlled mostly by solid-phase conduction; whereas, in the interior both solid cond...
TL;DR: The combustion synthesis of titanium silicide (Ti5Si3) was investigated in this paper, where the main combustion reaction (thermal explosion) occurs in the presence of a liquid phase and is usually preceded by a relatively small reaction in the solid state.
Abstract: The combustion synthesis (SHS) of titanium silicide (Ti5Si3) was investigated. The main combustion reaction (thermal explosion) occurs in the presence of a liquid phase and is usually preceded by a relatively small reaction in the solid state. The influence of Ti particle size on the dominance of each of these types of reactions was investigated. SEM observations and X-ray diffraction analyses indicate that the combustion synthesis of Ti5Si3 proceeds according to the following sequence: TiSi2→ TiSi → Ti5Si4→ Ti5Si3.
TL;DR: In this article, the effects of gas pressure and diluent content on the combustion synthesis of titanium nitride was investigated and an activation energy of 342 + plus minus 50 kJ {circle dot}mol{sup {minus}1}, which is in good agreement with reported values for the diffusion of nitrogen in Titanium nitride.
Abstract: This paper reports the effects of gas pressure and diluent content on the combustion synthesis of titanium nitride was investigated. Combustion of titanium powder samples containing TiN as a diluent in the concentration range 0 to 60 wt% was carried out in a nitrogen atmosphere at pressures in the range 0.1 to 1.4 MPA. Analysis of the dependence of combustion wave velocity on temperature gave an activation energy of 342 {plus minus} 50 kJ {circle dot}mol{sup {minus}1}, which is in good agreement with reported values for the diffusion of nitrogen in titanium nitride.