In the present study, a bubble generator and a bubble separator were designed and evaluated for an independent off-gas removal system of a small thorium molten salt reactor(TMSR) with reference to the design of the Oa...In the present study, a bubble generator and a bubble separator were designed and evaluated for an independent off-gas removal system of a small thorium molten salt reactor(TMSR) with reference to the design of the Oak Ridge National Laboratory(ONRL). The bubble generator employed a Venturi tube as its main body owing to its simplicity and highly reliable structure. A centrifugal separator was used as the bubble separator, taking advantage of the kinetic energy of fluid to create a centrifugal force to separate gas bubbles from the mixture flow. Both the bubble generator and the separator were demonstrated to have good potential to meet the performance requirements of an off-gas removal system for a small TMSR. With water and air as the working fluids, for the final designs of the two key pieces of equipment, a liquid flow rate exceeding 15 m3·h-1 can essentially make their performance meet the requirements of the off-gas removal system in terms of the average size of the generated bubbles and gas separation efficiency.展开更多
This paper introduces a new idea of controlling cavitation around a hydrofoil through a passive cavitation controller called artificial cavitation bubble generator （ACG）. Cyclic processes, namely, growth and implosi...This paper introduces a new idea of controlling cavitation around a hydrofoil through a passive cavitation controller called artificial cavitation bubble generator （ACG）. Cyclic processes, namely, growth and implosion of bubbles around an immersed body, are the main reasons for the destruction and erosion of the said body. This paper aims to create a condition in which the cavitation bubbles reach a steady-state situation and prevent the occurrence of the cyclic processes. For this purpose, the ACG is placed on the surface of an immersed body, in particular, the suction surface of a 2D hydrofoil. A simulation was performed with an implicit finite volume scheme based on a SIMPLE algorithm associated with the multiphase and cavitation model. The modified k-ε RNG turbulence model equipped with a modification of the turbulent viscosity was applied to overcome the turbulence closure problem. Numerical simulation of water flow over the hydrofoil equipped with the ACG shows that a low-pressure recirculation area is produced behind the ACG and artificially generates stationary cavitation bubbles. The location, shape, and size of this ACG are the crucial parameters in creating a proper control. Results show that the cavitation bubble is controlled well with a well-designed ACG.展开更多
A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and co...A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and column flotation. The dissolved air release occurred within the column separation system. As a potential application the column was investigated for its performance in separating emulsified oil droplets in oily wastewater. A high separation efficiency was obtained in a series of tests. The aeration performance of the bubble generator used in the dissolved-air flotation column was also studied in particular.展开更多
Aspiration spiral flow type centrifugal flotation machine takes full advantage of centrifugal force field and gravitational field, and strengthens flotation of coal slurry. As a new-type flotation machine of high effi...Aspiration spiral flow type centrifugal flotation machine takes full advantage of centrifugal force field and gravitational field, and strengthens flotation of coal slurry. As a new-type flotation machine of high efficiency, its key component is bubble generator. Which completes the process of ore pulp inflation and liberalization. The design, parameters and working principle of bubble generator provide the design of the same device in similar equipment with reference. The result of industrial operation shows that this machine is of such features as small occupational area, greater concentration ratio, high processing capacity, high efficiency and lower investment etc.展开更多
Widely used bioaerosol generators like Collison nebulizer probably produce electrostatically charged par- ticles, but the electrical charges carried by laboratory-generated airborne microorganisms using bubbling aeros...Widely used bioaerosol generators like Collison nebulizer probably produce electrostatically charged par- ticles, but the electrical charges carried by laboratory-generated airborne microorganisms using bubbling aerosolizers are poorly understood. In this study, we measured the fraction of neutral particles and num- ber of elementary charges per particle as a function of the aerodynamic diameter of airborne bacteria （Escherichia coli and Enterococcus hirae）. Bioaerosols were produced by a liquid sparging aerosolizer-type bubbling generator, with particle sizes ranging from roughly 0.6 to 2 p^m. The experimental setup included an electrostatic precipitator and real-time devices including an electrometer, aerodynamic particle sizer, and electrical low-pressure impactor. Experimental results obtained for various operating conditions showed that aerosols produced with a higher bubbling airflow contained a larger proportion of neutral particles （from around 30% to 50%） and that bacteria carried a greater average absolute number of elementary charges （from around -10 to -60 elementary units） than those under lower airflow. Under the investigated conditions, a neutralization step is unnecessary because it may have a negative effect on the viability of sensitive microorganisms. Our results suggest that the neutral fraction can be used down- stream of an electrostatic precipitator, and that this setup may have advantages over bipolar neutralizers.展开更多
基金financial support from the National Natural Science Foundation of China (51706149, 51709191, 51606130)the China Postdoctoral Science Foundation (2018M643474)。
文摘In the present study, a bubble generator and a bubble separator were designed and evaluated for an independent off-gas removal system of a small thorium molten salt reactor(TMSR) with reference to the design of the Oak Ridge National Laboratory(ONRL). The bubble generator employed a Venturi tube as its main body owing to its simplicity and highly reliable structure. A centrifugal separator was used as the bubble separator, taking advantage of the kinetic energy of fluid to create a centrifugal force to separate gas bubbles from the mixture flow. Both the bubble generator and the separator were demonstrated to have good potential to meet the performance requirements of an off-gas removal system for a small TMSR. With water and air as the working fluids, for the final designs of the two key pieces of equipment, a liquid flow rate exceeding 15 m3·h-1 can essentially make their performance meet the requirements of the off-gas removal system in terms of the average size of the generated bubbles and gas separation efficiency.
文摘This paper introduces a new idea of controlling cavitation around a hydrofoil through a passive cavitation controller called artificial cavitation bubble generator （ACG）. Cyclic processes, namely, growth and implosion of bubbles around an immersed body, are the main reasons for the destruction and erosion of the said body. This paper aims to create a condition in which the cavitation bubbles reach a steady-state situation and prevent the occurrence of the cyclic processes. For this purpose, the ACG is placed on the surface of an immersed body, in particular, the suction surface of a 2D hydrofoil. A simulation was performed with an implicit finite volume scheme based on a SIMPLE algorithm associated with the multiphase and cavitation model. The modified k-ε RNG turbulence model equipped with a modification of the turbulent viscosity was applied to overcome the turbulence closure problem. Numerical simulation of water flow over the hydrofoil equipped with the ACG shows that a low-pressure recirculation area is produced behind the ACG and artificially generates stationary cavitation bubbles. The location, shape, and size of this ACG are the crucial parameters in creating a proper control. Results show that the cavitation bubble is controlled well with a well-designed ACG.
基金Projects 50425414 supported by thte National Fund for Distinguished Young Scholars2006A019 by the Science and Technology Fund of China University of Mining &Technology
文摘A new type of device,a dissolved-air flotation column,was developed for separation of oily wastewater. The unique design idea of the dissolved-air flotation column is the combined use of dissolved-air flotation and column flotation. The dissolved air release occurred within the column separation system. As a potential application the column was investigated for its performance in separating emulsified oil droplets in oily wastewater. A high separation efficiency was obtained in a series of tests. The aeration performance of the bubble generator used in the dissolved-air flotation column was also studied in particular.
文摘Aspiration spiral flow type centrifugal flotation machine takes full advantage of centrifugal force field and gravitational field, and strengthens flotation of coal slurry. As a new-type flotation machine of high efficiency, its key component is bubble generator. Which completes the process of ore pulp inflation and liberalization. The design, parameters and working principle of bubble generator provide the design of the same device in similar equipment with reference. The result of industrial operation shows that this machine is of such features as small occupational area, greater concentration ratio, high processing capacity, high efficiency and lower investment etc.
文摘Widely used bioaerosol generators like Collison nebulizer probably produce electrostatically charged par- ticles, but the electrical charges carried by laboratory-generated airborne microorganisms using bubbling aerosolizers are poorly understood. In this study, we measured the fraction of neutral particles and num- ber of elementary charges per particle as a function of the aerodynamic diameter of airborne bacteria （Escherichia coli and Enterococcus hirae）. Bioaerosols were produced by a liquid sparging aerosolizer-type bubbling generator, with particle sizes ranging from roughly 0.6 to 2 p^m. The experimental setup included an electrostatic precipitator and real-time devices including an electrometer, aerodynamic particle sizer, and electrical low-pressure impactor. Experimental results obtained for various operating conditions showed that aerosols produced with a higher bubbling airflow contained a larger proportion of neutral particles （from around 30% to 50%） and that bacteria carried a greater average absolute number of elementary charges （from around -10 to -60 elementary units） than those under lower airflow. Under the investigated conditions, a neutralization step is unnecessary because it may have a negative effect on the viability of sensitive microorganisms. Our results suggest that the neutral fraction can be used down- stream of an electrostatic precipitator, and that this setup may have advantages over bipolar neutralizers.
