将HPGeγ谱仪应用于评估放射性管道内过滤器滞留量,需要知道探测器对过滤器内 γ辐射的绝对效率。根据 Monte Carlo 模拟光子输运过程的理论,对过滤器内 γ辐射的自吸收因子、路径上物质吸收因子、几何因子和晶体中的能量沉积等进行了...将HPGeγ谱仪应用于评估放射性管道内过滤器滞留量,需要知道探测器对过滤器内 γ辐射的绝对效率。根据 Monte Carlo 模拟光子输运过程的理论,对过滤器内 γ辐射的自吸收因子、路径上物质吸收因子、几何因子和晶体中的能量沉积等进行了描述。研究表明,实验检验模拟结果不确定度小于 10%。展开更多
In this work, the overall gas hold-up in the riser and down-comer of three internal airlift reactors with a working volume of 10.5, 32 and 200 l at the range of temperatures 18℃ - 21℃, under atmospheric pressure was...In this work, the overall gas hold-up in the riser and down-comer of three internal airlift reactors with a working volume of 10.5, 32 and 200 l at the range of temperatures 18℃ - 21℃, under atmospheric pressure was simulated using Com-putational Fluid Dynamics (CFD). The range of superficial gas velocity was 0.5 - 3 cm/s. The three reactors geometrically were similar to each other. CFD simulation and experimental data showed that the gas hold-up in the riser and down-comer increased by increasing the reactor scale. It was concluded that the simulated data were in good agreement with the experimental ones obtained from the literature.展开更多
The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Selection and design is one of them in parameter in the performance of three phase system....The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Selection and design is one of them in parameter in the performance of three phase system. This paper focuses on volume fraction and density effect on the phases hold-up in a 3 phase fluidize bed column containing liquid phase with 100 cm height and 20 cm diameter, in this case the solid phase with 0.15, 0.25, 0.35 volume fraction and density 2470, 3000, 4000, 5000 m3 dispersion into liquid phase and the gas phase enter the column through a sparger of 2 cm diameter with 0.02 m/s velocities. The results show as the solid phase volume fraction increases from 0.02 to 0.08 m/s. The gas hold-up decreases and solid hold-up increases. Solid phase density increases, so solid phase hold-up decreases and gas hold-up decreases.展开更多
This paper describes three-dimensional computational fluid dynamics(CFD) simulations of gas–liquid flow in a novel laboratory-scale bioreactor contained dual ventilation-pipe and double sieve-plate bioreactor(DVDSB)u...This paper describes three-dimensional computational fluid dynamics(CFD) simulations of gas–liquid flow in a novel laboratory-scale bioreactor contained dual ventilation-pipe and double sieve-plate bioreactor(DVDSB)used for sophorolipid(SL) production. To evaluate the role of hydrodynamics in reactor design, the comparisons between conventional fed-batch fermenter and DVDSB on the hydrodynamic behavior are predicted by the CFD methods. Important hydrodynamic parameters of the gas–liquid two-phase system such as the liquid phase velocity field, turbulent kinetic energy and volume-averaged overall and time-averaged local gas holdups were simulated and analyzed in detail. The numerical results were also validated by experimental measurements of overall gas holdups. The yield of sophorolipids was significantly improved to 484 g·L^(-1)with a 320 h fermentation period in the new reactor.展开更多
文摘In this work, the overall gas hold-up in the riser and down-comer of three internal airlift reactors with a working volume of 10.5, 32 and 200 l at the range of temperatures 18℃ - 21℃, under atmospheric pressure was simulated using Com-putational Fluid Dynamics (CFD). The range of superficial gas velocity was 0.5 - 3 cm/s. The three reactors geometrically were similar to each other. CFD simulation and experimental data showed that the gas hold-up in the riser and down-comer increased by increasing the reactor scale. It was concluded that the simulated data were in good agreement with the experimental ones obtained from the literature.
文摘The gas-liquid-solid fluidized bed has emerged in recent years as one of the most promising devices for three-phase operation. Selection and design is one of them in parameter in the performance of three phase system. This paper focuses on volume fraction and density effect on the phases hold-up in a 3 phase fluidize bed column containing liquid phase with 100 cm height and 20 cm diameter, in this case the solid phase with 0.15, 0.25, 0.35 volume fraction and density 2470, 3000, 4000, 5000 m3 dispersion into liquid phase and the gas phase enter the column through a sparger of 2 cm diameter with 0.02 m/s velocities. The results show as the solid phase volume fraction increases from 0.02 to 0.08 m/s. The gas hold-up decreases and solid hold-up increases. Solid phase density increases, so solid phase hold-up decreases and gas hold-up decreases.
基金Supported by the National Key Basic Research Program of China(No.2014CB745100)National Natural Science Foundation of China(No.21576197)+1 种基金Tianjin Research Program of Application Foundation and Advanced Technology(No.14JCQNJC06700)Technological Research and Development Programs of the China Offshore Environmental Services Ltd.(CY-HB-10-ZC-055)
文摘This paper describes three-dimensional computational fluid dynamics(CFD) simulations of gas–liquid flow in a novel laboratory-scale bioreactor contained dual ventilation-pipe and double sieve-plate bioreactor(DVDSB)used for sophorolipid(SL) production. To evaluate the role of hydrodynamics in reactor design, the comparisons between conventional fed-batch fermenter and DVDSB on the hydrodynamic behavior are predicted by the CFD methods. Important hydrodynamic parameters of the gas–liquid two-phase system such as the liquid phase velocity field, turbulent kinetic energy and volume-averaged overall and time-averaged local gas holdups were simulated and analyzed in detail. The numerical results were also validated by experimental measurements of overall gas holdups. The yield of sophorolipids was significantly improved to 484 g·L^(-1)with a 320 h fermentation period in the new reactor.
