A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based co...A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code,Young's technique was employed to track the interface between the explosion products and air,and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct,for point initiation,the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall,multi-peak values appear on pressure-time curve,and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct,explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products,and indicate that the ignition model and multi-material interface treatment method are feasible.展开更多
Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagati...Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.展开更多
Biomass has a tendency to adsorb mercury from the flue gas emissions from fossil fuel combustion. In this paper, we have established an experimental table of the adsorption of mercury vapor by rice husk ash according ...Biomass has a tendency to adsorb mercury from the flue gas emissions from fossil fuel combustion. In this paper, we have established an experimental table of the adsorption of mercury vapor by rice husk ash according to the method described in the Chinese national standard GB/T 5009.17-1996. The experimental stud）＇ was made using rice husk ash samples of different types and at different temperatures. The results show that the carbon content of the rice husk ash was 3.81% after treatment for 1 h at 600℃, the mercury removal rate was above 95%, but the adsorption efficiency was below 20% after incineration for 4 h. The adsorption efficiency of rice husk ash treated by H202 or HCI was very low, while the adsorption efficiency was very high when rice husk ash was pyrolytically carbonized or basified by NaOH; the adsorption efficiency ofbasified rice husk ash sample was up to 98.5%. The carbon content of rice husk ash could affect the adsorption of mercury to some degree, but the internal structure of the rice husk ash samples was a more important factor for adsorption.展开更多
基金Project(10572026) supported by the National Natural Science Foundation of China
文摘A two-dimensional multi-material code was indigenously developed to investigate the effects of duct boundary conditions and ignition positions on the propagation law of explosion wave for hydrogen and methane-based combustible mixture gas. In the code,Young's technique was employed to track the interface between the explosion products and air,and combustible function model was adopted to simulate ignition process. The code was employed to study explosion flow field inside and outside the duct and to obtain peak pressures in different boundary conditions and ignition positions. Numerical results suggest that during the propagation in a duct,for point initiation,the curvature of spherical wave front gradually decreases and evolves into plane wave. Due to the multiple reflections on the duct wall,multi-peak values appear on pressure-time curve,and peak pressure strongly relies on the duct boundary conditions and ignition position. When explosive wave reaches the exit of the duct,explosion products expand outward and forms shock wave in air. Multiple rarefaction waves also occur and propagate upstream along the duct to decrease the pressure in the duct. The results are in agreement with one-dimensional isentropic gas flow theory of the explosion products,and indicate that the ignition model and multi-material interface treatment method are feasible.
文摘Organic dust flames deal with a field of science in which many complicated phenomena like pyrolysis or devolatization of solid particles and combustion of volatile particles take place. One-dimensional flame propagation in cloud of fuel mixture is analyzed in which flame structure is divided into three zones. The first zone is preheat zone in which rate of the chemical reaction is small and transfer phenomena play significant role in temperature and mass distributions. In this model, it is assumed that particles pyrolyze first to yield a gaseous fuel mixture. The second zone is reaction zone where convection and vaporization rates of the particles are small. The third zone is convection zone where diffusive terms are negligible in comparison of other terms. Non-zero Biot number is used in order to study effect of particles thermal resistance on flame characteristics. Also, effect of particle size on combustion of micro organic dust is investigated. According to obtained results, it is understood that both flame temperature and burning velocity decrease with rise in the Biot number and particle size.
文摘Biomass has a tendency to adsorb mercury from the flue gas emissions from fossil fuel combustion. In this paper, we have established an experimental table of the adsorption of mercury vapor by rice husk ash according to the method described in the Chinese national standard GB/T 5009.17-1996. The experimental stud）＇ was made using rice husk ash samples of different types and at different temperatures. The results show that the carbon content of the rice husk ash was 3.81% after treatment for 1 h at 600℃, the mercury removal rate was above 95%, but the adsorption efficiency was below 20% after incineration for 4 h. The adsorption efficiency of rice husk ash treated by H202 or HCI was very low, while the adsorption efficiency was very high when rice husk ash was pyrolytically carbonized or basified by NaOH; the adsorption efficiency ofbasified rice husk ash sample was up to 98.5%. The carbon content of rice husk ash could affect the adsorption of mercury to some degree, but the internal structure of the rice husk ash samples was a more important factor for adsorption.
