Combustion, computational fluid dynamics

Computational fluid dynamics (CFD) is the analysis of systems involving fluid flow, energy transfer, and associated phenomena such as combustion and chemical reactions by means of computer-based simulation. CFD codes numerically solve the mass-continuity equation over a specific domain set by the user. The technique is very powerful and covers a wide range of industrial applications. Examples in the field of chemical engineering are ... 

Arvind Varma, Alexander S. Rogachev, Alexandra S. Mukasyan, and Stephen Hwang, Combustion Synthesis of Advanced Materials Principles and Applications J. A. M. Kuipers and W. P. M. van Swaaij, Computional Fluid Dynamics Applied to Chemical Reaction Engineering... 

A popular small-scale thermal biomass conversion method is combustion in grate furnaces. To meet the emission regulations for such a furnace, the operating conditions and design of the furnace have to be chosen carefully. Numerical models, known as computational fluid dynamics (CFD), can support the making of these choices, provided that accurate sub-models for the phenomena occurring in the oven are available. 

Appendix B consists of a systematic classification and review of conceptual models (physical models) in the context of PBC technology and the three-step model. The overall aim is to present a systematic overview of the complex and the interdisciplinary physical models in the field of PBC. A second objective is to point out the practicability of developing an all-round bed model or CFSD (computational fluid-solid dynamics) code that can simulate thermochemical conversion process of an arbitrary conversion system. The idea of a CFSD code is analogue to the user-friendly CFD (computational fluid dynamics) codes on the market, which are very all-round and successful in simulating different kinds of fluid mechanic processes. A third objective of this appendix is to present interesting research topics in the field of packed-bed combustion in general and thermochemical conversion of biofuels in particular. 

Saastamoinen J.J., Huttunen M., and Kjaldman L., Modelling of Pyrolysis and Combustion of Biomass Particles , the fourth European Computational Fluid Dynamics Conference, 7-11 Sept, Athens, Greece, (1998)... 

Using these methods, the elementary reaction steps that define a fuel s overall combustion can be compiled, generating an overall combustion mechanism. Combustion simulation software, like CHEMKIN, takes as input a fuel s combustion mechanism and other system parameters, along with a reactor model, and simulates a complex combustion environment (Fig. 4). For instance, one of CHEMKIN s applications can simulate the behavior of a flame in a given fuel, providing a wealth of information about flame speed, key intermediates, and dominant reactions. Computational fluid dynamics can be combined with detailed chemical kinetic models to also be able to simulate turbulent flames and macroscopic combustion environments. 

In practical combustion systems, such as CO boilers, the flue gas experiences spatial and temporal variations. Constituent concentration, streamline residence time, and temperature are critical to determining an efficient process design. Computational fluid dynamics (CFD) modeling and chemical kinetic modeling are used to achieve accurate design assessments and NO, reduction predictions based on these parameters. The critical parameters affecting SNCR and eSNCR design are listed in Table 17.4. 

Bnukal. C.E.. V.Y. Gershtein, and X. Li Computational fluid Dynamics in industrial Combustion, CRC Press. LLC.. Boca Raton. FL. 2000. 

Anderson Computational Fluid Dynamics The Basics with Applications Anderson Modem Compressible Flow With Historical Perspective Arora Introduction to Optimum Design Borman and Ragland Combustion Engineering Burton Introduction to Dynamic Systems Analysis Culp Principles of Energy Conversion... 

The following chapters present an overview of combustion and of CFD (Computational Fluid Dynamics) for combustion. The objective is not to repeat classical textbooks on these topics [379 306 288 334 340] but to focus on the place of instabilities in reacting flows and in CFD for reacting flows. These instabilities are found at many levels ... 

Griffin, M. E., Diwaker, R., Anderson, J. D., and Jones, E., Computational fluid dynamics applied to flows in an internal combustion engine. AIAA 16th Aerospace Sciences Meet., paper 78-57, January 1978. 

In most, but not all circumstances, the core gas temperature, T, is the natural reference temperature for the compressed gas because the highest temperature at the end of compression is responsible for the development of spontaneous ignition in the shortest time [88, 95]. Exceptionally, when the compression heats the reactants to temperatures that correspond to the region of ntc for that particular mixture, combustion may be initiated in the cooler boundary layer region. That is, gases which, at the end of compression, are colder than those in the adiabatic core control the duration of the ignition delay. This was demonstrated by Schreiber and coworkers by the simulation of alkane combustion, using various reduced kinetic schemes, in computational fluid dynamic calculations [102-104]. 

With increasing computer power, numerical methods, such as Computational Fluid Dynamics (CFD) became a useful tool for the optimisation of combustion processes in conjunction with experiments. 

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