摘要:

Abstract—In this paper ignition and extinction processes of catalytic reactions in a flat plate boundary layer flow are analyzed. The catalytic plate has finite thickness and thermal conductivity. It is assumed a global one-step and irreversible chemical reaction with Arrhenius kinetics and large activation energy. It is further assumed adiabatic boundary conditions for the lower surface and in both edges of the plate. For this case, the critical Damköhler number for ignition is not strongly affected by the axial heat conduction through the plate. On the other hand, the finite thermal conductivity has a big influence on the extinction process. An analytical expression for the critical Damköhler number for extinction is obtained.

ISSN:0010-2202    

DOI:10.1080/00102208408923767

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The conservation equations were solved numerically for the burned gas of methane-air and hydrogen-air to study the mechanism of NO2formation in the mixing region of hot burned gases with surrounding cool air. The spatial distributions of temperature and species concentrations in the gas mixture were predicted in a laminar flow field at atmospheric pressure. In the mixing region, NO2, is shown to be produced through the reaction NO+HO2→NO2+OH and consumed through the reactions NO2+H→NO+OH and NO2+OH→NO+HO2, depending on the temperature and composition of burned gas. The NO2/NOxratio in the mixing region decreases with a decrease in the burned gas temperature, and the NO2/NOxratio for the burned gas of hydrogen-air is lower than that for the burned gas of methane-air at the same burned gas temperature. The NO2formation in the mixing region also is shown to be affected by the temperature gradient in the mixing region and the concentration of active species such as H, OH and O as well as NO in the burned gas.

ISSN:0010-2202    

DOI:10.1080/00102208408923768

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The pyrolysis of n-tetradecane in free droplet vaporization was studied in a laminar flow furnace. Furnace exhaust products were sampled as a function of furnace temperature, process gas flow rate, and droplet spacing. The principal pyrolysis products in a helium environment were C1-C4hydrocarbons, polycyclic aromatic hydrocarbons (PAH) and soot. The light products were methane, ethane, ethylene, propylene, and acetylene, primarily. PAH were identified using high resolution, quartz capillary gas chromatography and high pressure liquid chromatography. A wide distribution of PAH was found, but most of the PAH contained four fused rings or less. At 600°C the droplets vaporized completely without pyrolysis. At 800°C, all the tetradecane is converted to light gases and PAH are first detected. PAH attain a maximum level near 1100°C before appreciable soot production commences. Pyrolysis product levels are also a strong function of residence time and droplet spacing; maximum PAH levels shift to higher temperature at reduced residence time, and PAH levels are increased substantially at reduced droplet spacing. A rough estimate of the overall activation energy for soot production in the range 1000-1400°C is 35 kcal/mole.

ISSN:0010-2202    

DOI:10.1080/00102208408923769

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The stability of burner flames for arbitrary Lewis number is considered on the basis of large activation energy modelling. Previous leading-order-only approaches are now extended to second order in Math (the inverse activation energy). The assumption that the unsteady perturbations are small (order ε) means that one must discuss the distinguished limit implicit in the product Math. lt is demonstrated here that different governing equations (and in particular the inner zone equation) are obtained in the two cases, θ1ε → 0 and θ1ε → ∞.

ISSN:0010-2202    

DOI:10.1080/00102208408923770

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

The intermediate zone of the two-stage trichloroethylene-oxygen-nitrogen flames is examined using a plug-flow model combined with the detailed chemical kinetics for the hydrogencatalyzed oxidation of CO and the elementary reactions involving chlorine and chlorinated species. The model predictions appear to be in reasonable agreement with the available experimental data.

ISSN:0010-2202    

DOI:10.1080/00102208408923771

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

An optical study of tbe interaction of a laminar, premixed, rod stabilized flame and a Karman vortex street has been performed. The technique used was laser tomography, in which the unburned gases are seeded with a silicone oil spray and then illuminated with a sheet of laser light. The oil spray evaporates and disappears in passing through the flame, making possible the high speed cinematography of the structure of the flame sheet.

ISSN:0010-2202    

DOI:10.1080/00102208408923772

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor

摘要:

In a previous paper the generation of a highly turbulent "puff" of combustion gas and its ignition characteristics in a quiescent combustion bomb were discussed. The present paper studies this puff-jet as an ignition source for a single cylinder, methane fueled, internal combustion test engine. The results indicate ignition characteristics comparable with those created by plasma jet ignition. Specifically,ignition delay and combustion times are reduced for both in comparison with a conventional spark ignition system.

ISSN:0010-2202    

DOI:10.1080/00102208408923773

出版商:Taylor & Francis Group    

年代:1984

数据来源: Taylor