Combustion Kinetic Modeling

Abstract

Combustion is a complex phenomenon characterized by the interaction and competition of various physical and chemical processes. The correct description of chemical changes requires the application of reaction mechanisms that consist of several hundreds or thousands of elementary reactions. This creates an opportunity for kinetic modeling to play important role in understanding the combustion phenomenon. This chapter provides an overview of combustion modeling, the main aim being to present a comprehensive knowledge base for combustion kinetic modeling. The coupling of fluid dynamics and chemical kinetics using commercial software such as CHEMKIN and FLUENT is also discussed. Moreover, an exemplary approach for reducing complex chemical reaction mechanisms is illustrated with reference to an H 2 + O 2 mixture in an adiabatic system. This approach involves the identification of redundant species via rate sensitivity analysis, and of redundant reactions, by principal component analysis of the rate sensitivity matrix. An eigenvalue–eigenvector analysis is used to extract meaningful kinetic information from linear sensitivity coefficients computed for all species of chemical mechanism at several time points. The main advantage of this method lies in its ability to reveal those parts of the mechanism, which consist of strongly interacting reactions, and to indicate their importance within the mechanism. By using the above procedures, reduced reaction mechanisms could be developed at different chosen conditions and employed in CFD codes in place of detailed mechanisms, giving due consideration to flow fields.

Experimental Investigation of Water Droplet Phase Change in Humidi-fied Air Flow

“…Further experiments had shown that, for water [10,[17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] et. all., for fuels and other liquids [34][35][36][37][38][39][40][41][42][43][44][45][46][47] the evaporation of a droplets takes place in a wide range of boundary conditions when taking into account the influence of environmental characteristics and the heat transfer boundary conditions of the droplets. Pure fuel [39], diesel and biodiesel [42,43], kerosene [44][45][46], various oils [37,38], fuel mixtures [35,41], and other multi-component fuel droplets [34,47] are popular subjects of experimental and theoretical studies of the fuel droplets.…”

Modeling of heat and mass transfer processes in phase transformation cycle of sprayed water into gas: 3. Energy and thermal states analysis of slipping droplet in a humid air flow

“…Many thermal technologies are based on by droplets heat transfer and phase transformations. Therefore, researchers' attention for water heat transfer processes and for heat exchange and phase transformations of hydrocarbon and other liquids dispersed into droplets do not decrease [1][2][3][4][5][6]. A liquid droplets phase transformation cycle combines condensing, unsteady and equilibrium evaporation modes τ ≡ 0 ÷ τ co ÷ τ nf ÷ τ f .…”

Large Scale Chemical Kinetic Models of Fossil Fuel Combustion: Adequate as Engineering Models—No More, No Less

“…The issue is not raised even in the latest review of combustion kinetic modeling. 3 As a result, a further aspect addressed herein concerns the nature of the potential value of these models. Are they already more than adequate as engineering tools, and can they convey any insight into the chemistry of combustion, which seems to be a growing interpretive temptation?…”

“…The fact that this is never generally commented upon, especially when it is clearly apparent that many of these models are chemically flawed, forms the basis of this paper. The issue is not raised even in the latest review of combustion kinetic modeling . As a result, a further aspect addressed herein concerns the nature of the potential value of these models.…”