A Numerical and Experimental Study of the No-Emission of Ceramic Foam Surface Burners

The NO-emission or flat premixed methane-air flames on a ceramic foam surface burner has been studied. This burner is developed for domestic heating systems, drying equipment and small industrial furnaces. A skeletal mechanism for lean-methane oxidation is used to compute the temperature and concentration fields of the major combustion species. The NO-emission is computed with a NO postprocessor using the output of the flame calculation as input The nitrogen chemistry computation is based on the reaction mechanism of Glarborg et al. (1992). Steady-state relations are introduced for most of the intermediates. In this way convection-diffusion-reaction equations for NO and HCN have to be solved only. The computation time is reduced significantly by using these post-calculations instead of solving the complete complex reaction scheme in one computational step. The computed flame temperature, surface temperature and NO-emission is compared with experimental results. The NO-emission is measured at several distances above the burner surface for several thermal loads and air ratios. The agreement with the numerical results shows that the proposed model is valid for predicting the flame temperature, surface temperature and NO-emission of radiant surface burners.