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 is studied using a comprehensive numerical model. A multi-slot burner with five fuel slots and six air slots arranged in an alternate manner has been analyzed. The power rating of the burner is kept as 10 kW and the air flow rate is fixed at 400% of stoichiometric air required for the net fuel flow rate. The numerical model incorporates a short chemical kinetic mechanism, variable thermo-physical properties, full multi-component 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 neighbouring 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 burner exit. Mass fraction of CO is affected by heating height and partial premixing. It remains almost constant for varying temperature of the impinging surfaces. Primary aeration of 20% is found to be optimum for higher net heat flux and lower CO emissions.