Numerical Study of Heat Transfer Characteristics of Impinging Syngas Flames From Multi-Slot Burner

Abstract

Characteristics of impinging flames from a multi-slot burner fueled by synthetic gas are studied using a comprehensive numerical model. A multi-slot burner with five fuel slots and six air slots arranged in an alternately has been analyzed. The power rating of the burner is kept at 10 kW, and the air flowrate is fixed at 400% of the stoichiometric air required for the net fuel flowrate. The numerical model incorporates a short chemical kinetic mechanism, variable thermophysical properties, full multicomponent diffusion, thermal diffusion and a radiation sub-model. The location of the solid surface from the burner exit, primary air in fuel stream, dimensions of solid surfaces, and their temperatures have been varied to study the heat flux distributions from impinging flames. Results show that the location of the solid surface from the burner ports and partial premixing affect the heat transfer characteristics. The heat fluxes received by the side and top surfaces depend on the characteristics of neighboring flames located around the central flame. The heat flux distribution and the net heat flux received by the surface are found to be uniform and optimum at a height of 90 mm from the burner exit. Increasing the length of the impinging surface has negligible influence on average heat flux and CO production. The mass fraction of CO is affected by heating height and partial premixing. It remains almost constant for varying temperatures of the impinging surfaces. Primary aeration of 20% is found to be optimum for higher net heat flux and lower CO emissions.