Experimental and Numerical Investigation of the Porous-free Flame Combustion
To broaden the lean combustion limit of the conventional porous burner(CPB)and further reduce the pollutants,a foam nickel metal porous-free flame burner(PFFB)is designed and experimentally studied for the combustion characteristics and the pollutant emissions.A same-size two-dimensional model is developed to numerically investigate the effects of the fractional hole area,relative height,and specific porosity on the flame,the temperature profile and the pollutant emissions.The results indicate that compared with CPB,PFFB performs a broader flame stability limit,with the stable combustion equivalence ratio of 0.50～0.67 for 1%of the fractional hole area,and the lean limit combustion equivalence ratio extends to 0.45.The fractional hole area has a relatively minor impact on the CO emission,reaching a minimum of 19.2 mg/m3.For NOx emission,the best denitrification effect is obtained at 4%of the fractional hole area(PFFB).Compared with CPB at φ=0.59,the NOx emission is reduced by 9.3%.The relative height of porous media significantly influences the pollutant emissions on PFFB.Under the experimental conditions,the relative height of 2/3 PFFB presents a reduction in CO emission by 5.2～140 mg/m3 compared with the relative height of 1/3,while NOx emission increases by 4.3～9.2 mg/m3.For PFFB at 4%of the fractional hole area,with the increase of specific porosity and porosity and the decrease of the pore diameter,an immersed and free flame is detected with the decrease of CO emission and the increase of NOx emission.Therefore,under specific pore characteristics,PFFB preserves the combustion performance of CPB while performing a broader flame stability limit,lower lean limit,and reducing the pollutant emissions.
porous media combustionporous-free flame burnerlow NOx combustion technologystate of flamenumerical simulation
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维普
