Studies On The Flame Characteristics Of Diffusion Combustion For Gas In Porous Media

Combustion in porous media as a new way of combustion has many advantages such as high combustion efficiency, low lean combustible limits and low emissions, etc., in comparison with the combustion in free space. During the last decade, most researches about combustion in porous media are premixed gas combustion, little about diffusion combustion. The thesis introduces the studies on the flame characteristics of combustion for diffused gas in porous media by experimental measurements and numerical simulation. The main research contents are as follows:(1) The experimental studies. The experimental facility was proposed, which consists of a combustor (quartz glass tube filled with packing particles), a gas flow system, a measurement system and so on, for the combustion of diffused gases in porous media. The flame characteristics and pollutant emissions of CH4/oxygen combustion in porous media are studied. The flame characteristics and pollutant emissions are observed and recorded for different experimental conditions, such as mass fraction of methane, inlet velocities, packed particle diameters. The influences on the flame characteristics and pollutant emissions by the mass fraction of methane, the inlet velocity and the packed particle diameters have been obtained.(2) The numerical simulations of the height of the diffusion combustion. The model, which is validated by comparing with experiments conducted by scholars, of CH4/oxygen combustion in porous media is carried out. The two-dimensional, two-temperature model is used to simulate the combustion fluid flow and heat transfer of the combustion by the software Fluent. The gas and porous medium temperature and different components distributions are obtained. The flame heights are observed and recorded by different parameters, such as mass fraction of methane, inlet velocities, packed particle diameters, solid thermal conductivities, molecular diffusion coefficients, mass dispersion coefficients, convective heat transfer coefficients and radiative heat transfer coefficients. The influences on the flame heights by these parameters have been reported. Further numerical simulation has been conducted. The accuracy of the numerical simulation has been proved by comparing with our own experimental values.(3) The numerical simulations of diffusion filtration radiative combustor. The model of CH4/oxygen radiative combustor in porous media is proposed. The efficiency of radiative combustor, the wall and center temperature of the combustor, the distribution of methane component are observed and recorded by different parameters, such as equivalence ratios, inlet velocities and packed particle diameters. The influences on the efficiency of radiative combustor by these parameters have been obtained.