Development of a gas phase combustion model suitable for low and high turbulence conditions

A novel hybrid gas phase combustion model suitable for low as well as high turbulent combustion conditions is proposed. In particular, in the region above the fuel bed of small-scale biomass combustion plants, gas phase mixing is highly influenced by laminar and low turbulence zones. Here, the eddy break-up combustion models are not valid because they were originally developed for highly turbulent flows. Therefore, a CFD gas phase reaction model applicable over the whole Reynolds range from laminar to turbulent flows is developed. It is a hybrid Eddy Dissipation Concept/finite rate kinetics model which calculates the effective reaction rate from laminar finite rate kinetics and the turbulent reaction rate and weights them depending on the local turbulent Reynolds number of the flow. To validate the proposed model, comparisons are made with experimental data for a series of jet flames covering laminar, transitional, and turbulent flow conditions. The simulation results show that the prediction of flame can be improved with the proposed hybrid combustion model.

[1]  R. Barlow,et al.  Piloted methane/air jet flames: Transport effects and aspects of scalar structure , 2005 .

[2]  Bassam B. Dally,et al.  Modeling turbulent reacting jets issuing into a hot and diluted coflow , 2005 .

[3]  Siegmar Wirtz,et al.  A CFD model for thermal conversion of thermally thick biomass particles , 2012 .

[4]  J. Janicka,et al.  Flow field measurements of stable and locally extinguishing hydrocarbon-fuelled jet flames , 2003 .

[5]  R. Barlow,et al.  Effects of turbulence on species mass fractions in methane/air jet flames , 1998 .

[6]  Song Fu,et al.  A Comparison of Algebraic and Differential Second-Moment Closures for Axisymmetric Turbulent Shear Flows With and Without Swirl , 1988 .

[7]  R. Graham,et al.  Fast pyrolysis of biomass , 1984 .

[8]  D. Spalding.  Mixing and chemical reaction in steady confined turbulent flames , 1971 .

[9]  Leonardo Tognotti,et al.  Key modeling issues in prediction of minor species in diluted-preheated combustion conditions , 2011 .

[10]  P. Coelho,et al.  Numerical simulation of a reversed flow small-scale combustor , 2013 .

[11]  Bjørn F. Magnussen,et al.  A Numerical Study of a Bluff-Body Stabilized Diffusion Flame. Part 2. Influence of Combustion Modeling And Finite-Rate Chemistry , 1996 .

[12]  Thomas Fleckl,et al.  Modification of a Magnussen Constant of the Eddy Dissipation Model for biomass grate furnaces by means of hot gas in-situ FT-IR absorption spectroscopy , 2003 .

[13]  Uwe Schnell,et al.  Simulation of detailed chemistry in a turbulent combustor flow , 1996 .

[14]  Stephen B. Pope,et al.  An explanation of the turbulent round-jet/plane-jet anomaly , 1978 .

[15]  A. Peters,et al.  Mathematical Modeling of a 2. 25 MWt Swirling Natural Gas Flame. Part 1: Eddy Break-up Concept for Turbulent Combustion; Probability Density Function Approach for Nitric Oxide Formation , 1995 .

[16]  C. Galletti,et al.  Numerical Investigation of a MILD Combustion Burner: Analysis of Mixing Field, Chemical Kinetics and Turbulence-Chemistry Interaction , 2012 .

[17]  I. Obernberger,et al.  Validation of flow simulation and gas combustion sub-models for the CFD-based prediction of NOx formation in biomass grate furnaces , 2010 .

[18]  NILS KRUSE,et al.  Wavy wall effects on turbulence production and large-scale modes , 2006 .

[19]  Bernd Meyer,et al.  Theoretical and numerical investigation on the EDC-model for turbulence-chemistry interaction at gasification conditions , 2009, Comput. Chem. Eng..

[20]  J. C. Ho,et al.  Comparison of different combustion models in enclosure fire simulation , 2001 .

[21]  I. Obernberger,et al.  A kinetic study on the potential of a hybrid reaction mechanism for prediction of NOx formation in biomass grate furnaces , 2011 .

[22]  Stephen B. Pope,et al.  Computationally efficient implementation of combustion chemistry using in situ adaptive tabulation , 1997 .

[23]  J. B. Perot,et al.  Modeling turbulent dissipation at low and moderate Reynolds numbers , 2006 .

[24]  B. Magnussen.  On the structure of turbulence and a generalized eddy dissipation concept for chemical reaction in turbulent flow , 1981 .

[25]  W. Peters,et al.  Product yields and kinetics from the vapor phase cracking of wood pyrolysis tars , 1989 .

[26]  Pratap Sathiah,et al.  Numerical Simulation of Delft-Jet-in-Hot-Coflow (DJHC) Flames Using the Eddy Dissipation Concept Model for Turbulence–Chemistry Interaction , 2011, 2101.08764.

[27]  A. Gómez-Barea,et al.  Characterization and prediction of biomass pyrolysis products , 2011 .

[28]  M. Mancini,et al.  Predicting NOx emissions of a burner operated in flameless oxidation mode , 2002 .

[29]  Masoud Rahimi,et al.  Kinetic and fluid dynamic modeling of ethylene jet flames in diluted and heated oxidant stream combustion conditions , 2013 .

[30]  Jan Vierendeels,et al.  Application of a New Cubic Turbulence Model to Piloted and Bluff-Body Diffusion Flames , 2001 .

[31]  Influence of computational aspects on simulations of a turbulent jet diffusion flame , 2003 .

[32]  I. S. Ertesvåg,et al.  The Eddy Dissipation Turbulence Energy Cascade Model , 2000 .

[33]  T. F. Smith,et al.  Evaluation of Coefficients for the Weighted Sum of Gray Gases Model , 1982 .

[34]  R. W. Bilger,et al.  On reduced mechanisms for methane-air combustion , 1991 .

[35]  B. Hjertager,et al.  On mathematical modeling of turbulent combustion with special emphasis on soot formation and combustion , 1977 .

[36]  J. Lumley,et al.  A First Course in Turbulence , 1972 .

[37]  Yaxin Su,et al.  Simulation of High Temperature Air Combustion with modified Eddy-Break-Up combustion model , 2012 .