Degenerate regimes of heterogeneous ignition and extinction of a particle in a gaseous oxidant

1983 ◽  
Vol 19 (3) ◽  
pp. 253-259
Author(s):  
A. G. Makarenko ◽  
B. I. Khaikin ◽  
S. I. Khudyaev
Keyword(s):  
Heterogeneous Ignition ◽  
Gaseous Oxidant

scholarly journals Abrupt but smaller than expected changes in surface air quality attributable to COVID-19 lockdowns

2021 ◽  
Vol 7 (3) ◽  
pp. eabd6696
Author(s):  
Zongbo Shi ◽  
Congbo Song ◽  
Bowen Liu ◽  
Gongda Lu ◽  
Jingsha Xu ◽  
...  
Keyword(s):  
Air Quality ◽  
Air Pollutant ◽  
Pollutant Emissions ◽  
Quality Improvements ◽  
Learning Technique ◽  
Emission Changes ◽  
Almost All ◽  
Gaseous Oxidant ◽  
Sophisticated Analysis ◽  
Limited Change

The COVID-19 lockdowns led to major reductions in air pollutant emissions. Here, we quantitatively evaluate changes in ambient NO2, O3, and PM2.5 concentrations arising from these emission changes in 11 cities globally by applying a deweathering machine learning technique. Sudden decreases in deweathered NO2 concentrations and increases in O3 were observed in almost all cities. However, the decline in NO2 concentrations attributable to the lockdowns was not as large as expected, at reductions of 10 to 50%. Accordingly, O3 increased by 2 to 30% (except for London), the total gaseous oxidant (Ox = NO2 + O3) showed limited change, and PM2.5 concentrations decreased in most cities studied but increased in London and Paris. Our results demonstrate the need for a sophisticated analysis to quantify air quality impacts of interventions and indicate that true air quality improvements were notably more limited than some earlier reports or observational data suggested.

An Asymptotic, Thermo-Diffusive Ignition Theory of Porous Solid Fuels

1976 ◽  
Vol 98 (2) ◽  
pp. 269-275 ◽  
Author(s):  
Choong Se Kim ◽  
Paul M. Chung
Keyword(s):  
Nonlinear Partial Differential Equations ◽  
Porous Solid ◽  
Solid Fuels ◽  
Thermal Ignition ◽  
Mass Balances ◽  
Governing Equations ◽  
Order Ordinary Differential Equation ◽  
First Order ◽  
Time Space ◽  
Gaseous Oxidant

The governing equations of thermal ignition are analyzed for porous solid fuel, such as coal, of various two-dimensional and axisymmetric geometries by the Laplace asymptotic method. Mass diffusion of the gaseous oxidant through the porous fuel is included. The nonlinear partial differential equations of energy and mass balances in time-space coordinates containing the Arrhenius volumic chemical reaction terms are analyzed. By employing the Laplace asymptotic technique and by invoking a certain limit theorem, the governing equations are reduced to a first order ordinary differential equation governing the fuel surface temperature, which is readily solved numerically. Detailed discussion of the effects of the various governing parameters on ignition is presented. Because of the basically closed-form nature of the solutions obtained, many general and fundamental aspects of the ignition criteria hitherto unknown are found.

Heterogeneous ignition modes for polymethyl methacrylate in a gaseous oxidizer stream

1976 ◽  
Vol 12 (3) ◽  
pp. 325-332 ◽  
Author(s):  
A. M. Grishin ◽  
G. N. Isakov
Keyword(s):  
Polymethyl Methacrylate ◽  
Heterogeneous Ignition ◽  
Gaseous Oxidizer

A strength model of heterogeneous ignition of metal particles

1992 ◽  
Vol 28 (1) ◽  
pp. 1-7 ◽  
Author(s):  
V. I. Rozenband ◽  
N. I. Vaganova
Keyword(s):  
Metal Particles ◽  
Strength Model ◽  
Heterogeneous Ignition

Effects of evaporation in the ignition of damp wood in a flowing gaseous oxidant

1986 ◽  
Vol 22 (2) ◽  
pp. 142-148
Author(s):  
G. N. Isakov ◽  
G. S. Kas'yanov
Keyword(s):  
Gaseous Oxidant

scholarly journals Gasification effects in the heterogeneous ignition of a condensed fuel by a hot gas

1978 ◽  
Vol 5 (11-12) ◽  
pp. 1199-1211 ◽  
Author(s):  
M. Kindelán ◽  
A. Liñán
Keyword(s):  
Heterogeneous Ignition ◽  
Hot Gas

scholarly journals Modeling of Effects of Volatile Matter Cloud on Heterogeneous Ignition of Single Coal Particles.

2000 ◽  
Vol 33 (1) ◽  
pp. 49-56 ◽  
Author(s):  
Hassan Katalambula ◽  
Jun-ichiro Hayashi ◽  
Kunihiro Kitano ◽  
Tadatoshi Chiba
Keyword(s):  
Volatile Matter ◽  
Heterogeneous Ignition ◽  
Coal Particles

A Method for Analyzing the Heterogeneous Ignition of Carbon/Char Particles

1992 ◽  
Vol 81 (4-6) ◽  
pp. 301-312 ◽  
Author(s):  
WEI BIAO FU ◽  
HONG FEI YAN
Keyword(s):  
Heterogeneous Ignition

The Effect of Potassium Carbonate on the Catalytic Properties for Methane Conversion with Ceria

2012 ◽  
Vol 161 ◽  
pp. 194-199
Author(s):  
Yue Juan Duan ◽  
Hua Wang ◽  
Yong Gang Wei ◽  
Kong Zhai Li ◽  
Xing Zhu ◽  
...  
Keyword(s):  
Solid Solution ◽  
Storage Capacity ◽  
Catalytic Properties ◽  
Fixed Bed ◽  
Oxygen Storage Capacity ◽  
Fixed Bed Reactor ◽  
Oxygen Storage ◽  
Incipient Wetness Impregnation ◽  
Solid Reaction ◽  
Gaseous Oxidant

Pure CeO2and a series of (x %) K-CeO2(x=1, 2, 3, 4) catalysts were respectively prepared by the precipitation and incipient wetness impregnation methods, and characterized by means of XRD, BET and H2-TPR techniques. The catalytic activity was investigated by the gas-solid reaction with methane in the absence of gaseous oxidant in a fixed bed reactor at 800 °C. The XRD measurement showed that doping of K2CO3did not change the structure of CeO2with the addition of K2CO3 without formation of Ce-K-O solid solution in these materials. Surface area of catalysts wasSubscript textdecreased with the impregnation amount of K2CO3. Reducibility of catalysts was obviously enhanced by the addition of K2CO3as shown in H2-TPR tests. The catalysts activity tests indicated that adding K2CO3to CeO2could promote the oxygen storage capacity of catalysts. K species in CeO2could affect the CO formation in methane oxidation.

Heterogeneous ignition of an aluminum particle in oxygen and water vapor

1970 ◽  
Vol 6 (3) ◽  
pp. 291-297 ◽  
Author(s):  
M. A. Gurevich ◽  
G. E. Ozerova ◽  
A. M. Stepanov
Keyword(s):  
Water Vapor ◽  
Aluminum Particle ◽  
Heterogeneous Ignition
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