Numerical simulations are performed both for the single airflow and air-PMtwo-phase flow in wall flow diesel participate filters (DPF) for the first time. The calculationdomain is divided into two regions. In. the inl...Numerical simulations are performed both for the single airflow and air-PMtwo-phase flow in wall flow diesel participate filters (DPF) for the first time. The calculationdomain is divided into two regions. In. the inlet and outlet flow channels, the simulations areperformed for the steady and laminar flow; In the porous filtration walls, the calculation model forflow in porous media is used. The Lagrange two-phase flow model is used to calculate the air-PMflow in DPF, for the dispersed phase (PM), its flow tracks are obtained by the integrating of theLagrange kinetic equation. The calculated velocity, pressure distribution and PM flow tracks in DPFare obtained, which exhibits the main flow characteristics in wall flow DPF and will be help for theoptimal design and performance prediction of wall flow DPF.展开更多
In this paper, a new method-Distributed La-grange Multiplier/fictitiousdomain (DLM) method for partic-ulate flows was improved. A rectangular mesh was introduced todiscretize the domain, and the buoyant force was cons...In this paper, a new method-Distributed La-grange Multiplier/fictitiousdomain (DLM) method for partic-ulate flows was improved. A rectangular mesh was introduced todiscretize the domain, and the buoyant force was considered for predicting the positions ofparticles. In order to validate the presented algorithm, the sedimentation of a single circularparticle was simulated using different mesh sizes and time steps firstly. The results show that thesimulation is independent of the mesh size as well as the time step. And then, the interactionsbetween two falling particles, including drafting, kissing and tumbling, and the sedimentation of 18particles also have been simulated with the code.展开更多
Some of the heavy metals in coal and wastes vaporize during combustion, concentrate in fine particulates, and emit with the flue gas into the atmosphere, to produce adverse effect on environment and health. This study...Some of the heavy metals in coal and wastes vaporize during combustion, concentrate in fine particulates, and emit with the flue gas into the atmosphere, to produce adverse effect on environment and health. This study first investigates the fate of the heavy metal species, especially Pb, Cd and Cr, known as semi-volatile, in various flue gases, especially in the presence of HCI and SO2, by chemical equilibrium calculation, in which, Si and Ca were proposed as base sorbent materials to capture Pb, Cd and Cr. Then Si- and Ca-based compounds as well as waste materials used as sorbents were optimized to capture the heavy metals. Finally, the optimal sorbent was tested in actual burning of dried sewage sludge as solid fuel, to evaluate the effectiveness of the sorbent. Calculated results show that Cl increases the volatility of most heavy metals, while SO2 enhances formation of condensed phases. Among the sorbents tested, kaolin appears most efficient to capture Pb and Cd. For sludge combustion with kaolin addition, both Pb and Cd were shifted from sub-micron to macro-sized particles, and accompanied by considerable decrease of 0.1 μm particles.展开更多
In the non-spherical particulate turbulent flows, a set of new fluidfluctuating velocity equations with the non-spherical particle source term were derived, then a newmethod, which treats the slowly varying functions ...In the non-spherical particulate turbulent flows, a set of new fluidfluctuating velocity equations with the non-spherical particle source term were derived, then a newmethod, which treats the slowly varying functions and rapidly varying functions separately, wasproposed to solve the equations, and finally the turbulent intensity and the Reynolds stress of theflu-id were obtained by calculating the fluctuating velocity statlsti-cally. The equations andmethod were used to a paniculate tur-bulent pipe flow. The results show that the turbulent intensityand the Reynolds stress are decreased almost inverse proportion-ally to the fluctuating velocityratio of particle to fluid. Non-spherical particles have a greater suppressing effect on thetur-bulence than the spherical particles. The particles with short re-laxation time reduce theturbulence intensity of fluid, while the particles with long relaxation time increase the turbulenceinten-sity of fluid. For fixed particle and fluid, the small particles sup-press the turbulence andthe large particles increase the turbu-ience.展开更多
SINKING particulate organic matter of the sea plays an important role in marine environment. Itnot only provides food for marine organisms and takes part in chemical cycling, but also pro-vides sedimentary organic mat...SINKING particulate organic matter of the sea plays an important role in marine environment. Itnot only provides food for marine organisms and takes part in chemical cycling, but also pro-vides sedimentary organic matter for marine sediments. Therefore, researchers always payclose attention to the source and processes of transport and transformation of marine sinkingparticulate organic matter. Its transport process can be understood by measuring the展开更多
Phytoremediation as a sustainable and inexpensive technology based on the removal of pollutants from the environment by plants is becoming an increasingly important objective in plant research. In this study, biologic...Phytoremediation as a sustainable and inexpensive technology based on the removal of pollutants from the environment by plants is becoming an increasingly important objective in plant research. In this study, biological cycles of five nutrient elements （N, P, K, Ca, and Mg） and eight heavy metal elements （Fe, Cu, Zn, Mn, Cd, Ni, Pb and Co） were examined in young paniculed goldraintree （Koelreuteria paniculata Laxm） and common elaeocarpus （Elaeocarpus decipens） mixed stands in an abandoned mining area. We found that after vegetation restoration in abandoned mining areas, the organic matter and concentrations of nutrient elements were significantly increased and the heavy metal elements were significantly decreased, the annual retention, uptake and return were 75.0, 115.4, and 40.3 kg/hm^2 for nutrient elements, and 1 878.0, 3 231.0 and 1 353.0 g/hm^2 for heavy metal elements, respectively, with the utilization coefficient, cycling coefficient and turnover rate of 0.92, 0.35 and 0.32 for nutrient elements, and 1.24, 0.42 and 1.92 for heavy metal elements, respectively. Our results suggested that the vegetation restoration in abandoned mining areas had significant effects in improving environmental conditions, enhancing soil available nutrients, and ensuring human health.展开更多
文摘Numerical simulations are performed both for the single airflow and air-PMtwo-phase flow in wall flow diesel participate filters (DPF) for the first time. The calculationdomain is divided into two regions. In. the inlet and outlet flow channels, the simulations areperformed for the steady and laminar flow; In the porous filtration walls, the calculation model forflow in porous media is used. The Lagrange two-phase flow model is used to calculate the air-PMflow in DPF, for the dispersed phase (PM), its flow tracks are obtained by the integrating of theLagrange kinetic equation. The calculated velocity, pressure distribution and PM flow tracks in DPFare obtained, which exhibits the main flow characteristics in wall flow DPF and will be help for theoptimal design and performance prediction of wall flow DPF.
文摘In this paper, a new method-Distributed La-grange Multiplier/fictitiousdomain (DLM) method for partic-ulate flows was improved. A rectangular mesh was introduced todiscretize the domain, and the buoyant force was considered for predicting the positions ofparticles. In order to validate the presented algorithm, the sedimentation of a single circularparticle was simulated using different mesh sizes and time steps firstly. The results show that thesimulation is independent of the mesh size as well as the time step. And then, the interactionsbetween two falling particles, including drafting, kissing and tumbling, and the sedimentation of 18particles also have been simulated with the code.
基金supported by the National Natural Science Foundation of China (Grants 50721140649,50776038 and 50721005)The Programme of Introducing Talents of Discipline to Universities("111" Project,No.B06019)Program for New Century Excellent Talents in University (No.NCET-08-0227)
文摘Some of the heavy metals in coal and wastes vaporize during combustion, concentrate in fine particulates, and emit with the flue gas into the atmosphere, to produce adverse effect on environment and health. This study first investigates the fate of the heavy metal species, especially Pb, Cd and Cr, known as semi-volatile, in various flue gases, especially in the presence of HCI and SO2, by chemical equilibrium calculation, in which, Si and Ca were proposed as base sorbent materials to capture Pb, Cd and Cr. Then Si- and Ca-based compounds as well as waste materials used as sorbents were optimized to capture the heavy metals. Finally, the optimal sorbent was tested in actual burning of dried sewage sludge as solid fuel, to evaluate the effectiveness of the sorbent. Calculated results show that Cl increases the volatility of most heavy metals, while SO2 enhances formation of condensed phases. Among the sorbents tested, kaolin appears most efficient to capture Pb and Cd. For sludge combustion with kaolin addition, both Pb and Cd were shifted from sub-micron to macro-sized particles, and accompanied by considerable decrease of 0.1 μm particles.
文摘In the non-spherical particulate turbulent flows, a set of new fluidfluctuating velocity equations with the non-spherical particle source term were derived, then a newmethod, which treats the slowly varying functions and rapidly varying functions separately, wasproposed to solve the equations, and finally the turbulent intensity and the Reynolds stress of theflu-id were obtained by calculating the fluctuating velocity statlsti-cally. The equations andmethod were used to a paniculate tur-bulent pipe flow. The results show that the turbulent intensityand the Reynolds stress are decreased almost inverse proportion-ally to the fluctuating velocityratio of particle to fluid. Non-spherical particles have a greater suppressing effect on thetur-bulence than the spherical particles. The particles with short re-laxation time reduce theturbulence intensity of fluid, while the particles with long relaxation time increase the turbulenceinten-sity of fluid. For fixed particle and fluid, the small particles sup-press the turbulence andthe large particles increase the turbu-ience.
文摘SINKING particulate organic matter of the sea plays an important role in marine environment. Itnot only provides food for marine organisms and takes part in chemical cycling, but also pro-vides sedimentary organic matter for marine sediments. Therefore, researchers always payclose attention to the source and processes of transport and transformation of marine sinkingparticulate organic matter. Its transport process can be understood by measuring the
基金Supported by the National Natural Science Foundation of China （No. 30571487the Key project of State Forestry Administration（2006-11, 2006-17）+1 种基金the Urban Forest Ecological Key Laboratory of Hunan Province（No. 06FJ3083）and the Platform Construction Project of the Ministry of Science and Technology of China（No. 20021220）.
文摘Phytoremediation as a sustainable and inexpensive technology based on the removal of pollutants from the environment by plants is becoming an increasingly important objective in plant research. In this study, biological cycles of five nutrient elements （N, P, K, Ca, and Mg） and eight heavy metal elements （Fe, Cu, Zn, Mn, Cd, Ni, Pb and Co） were examined in young paniculed goldraintree （Koelreuteria paniculata Laxm） and common elaeocarpus （Elaeocarpus decipens） mixed stands in an abandoned mining area. We found that after vegetation restoration in abandoned mining areas, the organic matter and concentrations of nutrient elements were significantly increased and the heavy metal elements were significantly decreased, the annual retention, uptake and return were 75.0, 115.4, and 40.3 kg/hm^2 for nutrient elements, and 1 878.0, 3 231.0 and 1 353.0 g/hm^2 for heavy metal elements, respectively, with the utilization coefficient, cycling coefficient and turnover rate of 0.92, 0.35 and 0.32 for nutrient elements, and 1.24, 0.42 and 1.92 for heavy metal elements, respectively. Our results suggested that the vegetation restoration in abandoned mining areas had significant effects in improving environmental conditions, enhancing soil available nutrients, and ensuring human health.
