摘要:

A thermal extinction model of two reactant, curved flames is presented using an asymptotic expansion with the reasonable condition of a large activation energy or the reaction rate. The preferential diffusions of the two reactants in the curved flames modify the thermal extinction condition of the flames. The thermal extinction model was found to explain the characteristics in quenching of cellular flames observed in H2-O2-N2flames

ISSN:0010-2202    

DOI:10.1080/00102208008952399

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Magnesia powder injected into the flue gas airheater inlet (or outlet) on oil-fired power plant is being evaluated as a possible palliative to H2SO4deposition and acid smut emission problems. This paper considers laboratory scale and theoretical work aimed at quantifying one of the mechanisms influencing additive performance, namely the reaction between sulphuric acid vapour and magnesia particles suspended in the flue gas. The model derived lo describe the sulphation kinetics has been usedto estimate the amount of acid vapour likely to be neutralized by commercial additives. The results have been compared with measurements of H2SO4vapour depletion between the airheater and stack of a 500 MW(e) unit. This work provides guidelines for estimating the extent of the reduction in sulphuric acid vapour concentrations which may be attained provided that the additive powder residence times and size spectrum are well established

ISSN:0010-2202    

DOI:10.1080/00102208008952400

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A streamwise laminar diffusion flame in a boundary layer flow is modelled for a hydrogen-oxygen system with six step reaction kinetics. The method of matched asymptotic expansions, based on the existence of a large value of the Damkohler number, provides first order inner and outer temperature and concentration solutions from which composite series are constructed for a range of fresstream reactant concentrations, some of which are chosen to coincide with experimental situations. In these cases comparisons between theoretical and experimental results are made

ISSN:0010-2202    

DOI:10.1080/00102208008952401

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Lawrence Livermore Laboratory has completed an exploratory drilling program at the site of the Hoe Creek II Field Experiment on in situ coal gasification. We have used the results to further define the boundaries of the gasification zone. The gasification zone was 12 to 16 m wide and extended at least 7.6 m behind the injection well and 18 m toward the production well. All the coal within 2.9 m of the injection well was gasified despite an override condition that existed almost from the start of forward-combustion gasification. Cavity-spreading mechanisms that do not depend on the product flow paths being at the bottom of the seam are suggested. Natural convection may drive these mechanisms. For these mechanisms to function the injection point must be at the bottom of the coal seam

ISSN:0010-2202    

DOI:10.1080/00102208008952402

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

An experimental measurement and a model calculation were performed to study the effects of probing conditions on NO2/NOxratios obtained by a probe sampling from flames. Four quartz probes, which were different in the sample pressure, the cooling rate of the sample and the surface to volume ratio, were used to sample the combustion gas of a premixed CH4-air flame. The effects of probing conditions were evaluated by the model calculation based on the concept that NO2was primarily formed by the NO-NO2reactions in the probe. The NO2/NOxratios obtained by the probe measurement were compared with those by the model calculation, and reasonable agreement was found between them under the fuel-lean conditions

ISSN:0010-2202    

DOI:10.1080/00102208008952403

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

A new formulation of the spectral interpretation of turbulent burning velocities is proposed. The correlation formula based on this interpretation is tested against existing experimental data on turbulent burning velocities

ISSN:0010-2202    

DOI:10.1080/00102208008952404

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The paper reports recent results on the burning of parallel combustible walls. Tests are discussed which were carried out with walls made of wicks ˜1 m high soaked with methanol and toluene-methanol mixtures. A maximum increase in burning rate of about 40 percent over the single wall case is calculated from a view-factor analysis of the radiative heat exchange between the wails: this is consistent with the experimental measurements. The predicted maximum in burning rate occurs at a wall spacing of about 20 percent of the wall height. The analysis, which is based on a careful examination of the contribution by radiation to the energy budget for the burning of single walls, should not be regarded as a theory for parallel burning. There is indication, however, that the view-factor analysis may be reasonably accurate thanks to some cancellation among the phenomena which are not considered by the theory

ISSN:0010-2202    

DOI:10.1080/00102208008952405

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

Rigorous bounds on temperature and concentration are obtained for a model reacting system incorporating spatial variation, reactant consumption, and Arrhenius kinetics. Similar bounds are obtained for the Semenov (spatially uniform) approximation. Temperatures predicted by the Frank-Kamenetskii (stationary) approximation are shown to be upper bounds on the temperature of the complete time-dependent system. The latter supports numerical and approximate analytic arguments that the critical value of the Frank-Kamenetskii heat generation parameter in the stationary approximation is a lower bound on analogously defined critical parameter values in the complete system. The fundamental mathematical tool is a comparison result for systems of parabolic partial differential equations

ISSN:0010-2202    

DOI:10.1080/00102208008952406

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

This paper describes a finite difference experiment to simulate the transient development of the convection column above a strip of uniform high temperature source in a stratified uniform cross flow atmosphere. The κ-ϵ model of turbulence is used and an upstream weighted scheme for this vorticity-stream function formulation is employed. Some computation results for a 195 m wide source are presented. The immediate goal of the undertaking was to devise a scheme which could yield realistic flow “boundary conditions” in the immediate vicinity of a fire to enable one to model the detailed structure of the fire region. The predictions arc quite consistent with observations and this provides the link between the heat source and environmental parameters. This scheme, together with a refined near zone fire model, can be used to describe the interplay between the heat source (fire) component and the environmental components of a mass fire system

ISSN:0010-2202    

DOI:10.1080/00102208008952407

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor

摘要:

The oxidation of cyanogen was studied in the temperature range of 950-1050°C using a flow system and Vycor stirred-flow reactor. The rate was found to be first-order in cyanogen and zero-order in oxygen. The activation energy and log frequency factor are 56.3 (kcal/mole) and 9.2 (using sec−1) respectively. The oxidation products were CO, CO2and N2O, no other oxides of nitrogen were found. The implications of these observations on the mechanism of NO formation from fuel nitrogen are discussed

ISSN:0010-2202    

DOI:10.1080/00102208008952408

出版商:Taylor & Francis Group    

年代:1980

数据来源: Taylor