Mathematical Modelling of Thermal NOX Emissions in Combustion Chambers

  • K. A. Pericleous
  • I. W. Clark
  • N. C. Markatos
Conference paper
Part of the EUROTHERM Seminars book series (EUROTHERM, volume 17)


A mathematical model of combustion in typical burners is presented. The model differs from other similar ones presented by other investigators, in that it features a two-step approach, which allows the calculation of the main exothermic reactions of fuel in air, and of those responsible for the formation of pollutants, specifically nitrogen oxides (NOx) to be performed in tandem. The model uses CFD techniques to compute the flowfield in the burner and transport equations are solved for all relevant reacting species. To ensure industrial relevance all factors affecting combustion performance and heat transfer have been included, i.e. three- dimensionality, an exact representation of geometry, the air swirler, turbulence and radiation.

In the first step, the calculation deals with the combustion of methane in air for which a global, single step reaction is assumed. The limiting effect of turbulence on reaction rate is taken into account using an eddy-break-up model. Radiation between the burner walls, the flame and intervening gas is accounted for using a flux model.

In the second step, the product stream resulting from the first step calculation is analysed to determine the concentrations of O, OH and H radicals, subsequently used in a Zeldovich type scheme to form oxides of nitrogen. The convective and diffusive transport terms of the first step are used to solve conservation equations for N and NO.

The paper illustrates the technique in an application to an axial recirculating burner.


Flame Structure Furnace Wall Burner Design Turbulent Exchange Coefficient Furnace Size 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.




Empirical expression in combustion model


Species concentration


Turbulent kinetic energy per unit mass, J/kg


Mole fraction


Mass fraction


Ideal gas constant


Reaction rate per unit volume, kgs/m3


Stoichiometric oxidant to fuel ratio


Source term in finite difference equations


Temperature, K


Activation temperature, K

\(\vec v\)

Velocity vector

Greek Symbols


Turbulent exchange coefficient for variable ϕ


Turbulence energy dissipation rate per unit mass, W/kg


Dynamic viscosity, Ns/m2


Density, kg/m3


General dependant variable





Nitrogen oxides










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Copyright information

© Springer-Verlag Berlin, Heidelberg 1991

Authors and Affiliations

  • K. A. Pericleous
    • 1
  • I. W. Clark
    • 2
  • N. C. Markatos
    • 3
  1. 1.Centre for Numerical Modelling and Process AnalysisThames PolytechnicLondonUK
  2. 2.Flomerics Inc.USA
  3. 3.National Technical UniversityAthensGreece

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