Emission of NO_x in Flame Impingement Heat Transfer

ABSTRACT

A theoretical model of both premixed and diffusion turbulent flames impinging normally on a plane circular target plate has been developed to predict the influences of jet Reynolds number, ratio of plate separation distance to nozzle diameter, and equivalence ratio on NO_x emission in flame impingement heat transfer. The model is based on the numerical solution of equations for conservation of mass, momentum and energy. Methane and air have been considered as fuel and oxidizer respectively. Global two-step irreversible reaction kinetics has been employed for the oxidization of methane. The RNG k-ε model has been used to compute the turbulence, and the Discrete Ordinate model has been used for radiative transfer in the flame. The computation for the formation of NO_x has been made following Zeldovich mechanism. It is revealed that formation of NO_x is significant in a fuel rich mixture of ER = 2 and is formed at a location adjacent to the plate surface. The formation of NO_x is less in a diffusion flame as compared to that in a premixed flame. In case of both premixed and diffusion flames of stoichiometric mixture, an increase in plate separation distance (H/d) decreases the exit bulk NO_x concentration, while the trend is reversed in case of a fuel rich mixtures (ER = 2).

---

Full Text (PDF)

© 2010 Research Publishing Services