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Clean Air: International Journal on Energy for a Clean Environment

ISSN for PRINT: 1561-4417

Institutional price:	$451.00
Issues per year:	4

Best Paper Award Selection - Editorial Board Site

2006, Volume7

99 pages

DOI: 10.1615/InterJEnerCleanEnv.v7.i2

Issue price - $128.00

PREDICTION OF NO_x FORMATION IN A PRACTICAL-SCALE, NONPREMIXED TURBULENT FLAME USING EDDY DISSIPATION AND RADIATIVE FLAMELET COMBUSTION MODELS

S. K. Sangha
School of Process, Environmental and Materials Engineering, The University of Leeds, Leeds LS2 9JT, UK

T. Mahmud
School of Process, Environmental and Materials Engineering, The University of Leeds, Leeds LS2 9JT, UK

C. Y. Ma
School of Process, Environmental and Materials Engineering, The University of Leeds, Leeds LS2 9JT, UK

ABSTRACT

A CFD-based combustion model coupled with a NOx postprocessing model has been applied to simulate a practical-scale, turbulent nonpremixed natural gas flame studied experimentally in a 3 MW furnace at the International Flame Research Foundation (Michelfelder and Lowes, 1974). The combustion is modeled using a radiative flamelet combustion (RFC) model (Ma et al., 2002), which is an extension of the mixedness-reactedness flamelet combustion model of Bradley et al, (1990) and the eddy-dissipation combustion (EDC) model of Magnussen and Hjertager (1976). To account for the radiation heat transfer, a comprehensive radiation model, namely, the discrete transfer method of Lockwood and Shah (1980), has been introduced into the combustion code. The turbulence is represented by the k-ε; model with the standard values of the constants and variants of C_ε1. The predicted velocity, temperature, and major species concentration fields obtained from both combustion models have been used to calculate nitric oxide (NO) formation in the furnace. The computational results are compared with experimental data for gas temperature, oxygen, and NO concentrations. The EDC model is unable to capture the effects of finite-rate reactions and hence fails to predict the flame structure in the near burner region causing the overpredictions of NO concentrations in this region. The RFC model reproduces the overall structure of the flame reasonably well and shows better agreement of the predicted NO concentrations with measurements.