Toward a steady-state theory of heterogeneous ignition and extinction of a particle in a heated gaseous oxidizer

Калінчак, В. В.; Orlovskaya, S. G.

doi:10.1007/bf00870734

Cited by 2 publications

(1 citation statement)

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“…In our previous works [2,6], thermophysical proper ties were associated with a temperature of 450 K. How ever, further studies [10] demonstrated that these prop erties should be associated with the arithmetic mean temperature of the catalyst and gas medium. Because the parameter examined here is the effective gas tem perature, the temperature dependences of thermophys ical properties will be analyzed using the characteristic temperature of the gas medium ( = 450 K): …”

Section: Problem Formulationmentioning

confidence: 85%

High-temperature ammonia oxidation over a platinum catalyst under conditions of the parallel formation of nitrogen-containing products

2015

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Experimental data on the effect of the temperature of air containing low ammonia concentrations on the temperature and rate of catalytic ammonia combustion over a platinum catalyst as a function of the NH 3 concentration and catalyst particle diameter are analyzed with account taken of thermal radiation under the assumption that nitrogen and nitric oxide form in parallel. At relatively low air temperatures (near the combustion extinction point), the ammonia combustion temperature is determined by the nitrogen forma tion reaction (which releases a larger amount of heat and is characterized by a lower activation energy). At higher air temperatures and ammonia concentrations, the combustion temperature is determined by the nitric oxide formation reaction (which releases a smaller amount of heat and is characterized by a higher acti vation energy). The dependence of the critical temperature of the gas mixture on the catalyst particle diam eter under conditions of the catalytic autoignition of the combustible gas and combustion extinction (at low ammonia concentrations) has been determined and analyzed for the case in which there is radiative heat transfer between the gas and the cold walls of the reactor.

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Section: Problem Formulationmentioning

confidence: 85%

High-temperature ammonia oxidation over a platinum catalyst under conditions of the parallel formation of nitrogen-containing products

2015

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Processes defining smouldering combustion: Integrated review and synthesis

Torero

Gerhard

Martins

et al. 2020

Progress in Energy and Combustion Science

116

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Smouldering combustion is an important and complex phenomenon that is central to a wide range of problems (hazards) and solutions (applications). A rich history of research in the context of fire safety has yet to be integrated with the more recent, rapidly growing body of work in engineered smouldering solutions. The variety of disciplines, materials involved, and perspectives on smouldering has resulted in a lack of unity in the expression of key concepts, terminology used, interpretation of results, and conclusions extracted. This review brings together theoretical, experimental, and modelling studies across both fire safety and applied smouldering research to produce a unified conceptual understanding of smouldering combustion. The review includes (i) a synthesis of nomenclature to generate a consistent set of terms for the underlying processes, (ii) an overview of smouldering emissions and emission treatment systems, (iii) a distillation of ignition and extinction research, including the role of heat losses and factors underpinning smouldering robustness, (iv) a review of the temporal and spatial distribution of heat and mass transfer processes as well as their solution using analytical and numerical methods, (v) a summary of smouldering chemical kinetics, and (vi) a summary of key gaps and opportunities for future research. Beyond merely review, a new conceptual model is provided that articulates similarities and critical differences between the two main smouldering systems: porous solid fuels and condensed fuels in inert porous media. A quantitative analysis of this conceptual model reveals that the evolution of a smouldering front, while a local process, is determined by a global energy balance that is cumulative in time and has to be integrated in space. As such, the fate of a smouldering reaction can be predicted before the effects of global heat exchange have affected the reaction. This approach is relevant to all forms of smouldering propagation (including fire safety), but it is particularly important when using smouldering as an engineered process that results in the positive use of the energy released by the smouldering reaction (applied smouldering). In applied smouldering, predicting the fate of a reaction ahead of time allows operators to modify the conditions of the process to maintain self-sustained smouldering propagation and thus fully harness the benefits of the reaction.

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Toward a steady-state theory of heterogeneous ignition and extinction of a particle in a heated gaseous oxidizer

Cited by 2 publications

References 0 publications

High-temperature ammonia oxidation over a platinum catalyst under conditions of the parallel formation of nitrogen-containing products

High-temperature ammonia oxidation over a platinum catalyst under conditions of the parallel formation of nitrogen-containing products

Processes defining smouldering combustion: Integrated review and synthesis

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