为了探究运行参数对分散相液滴的运动、聚并过程的影响,采用VOF(volume of fluid)方法捕捉分散相与连续相的流体间界面,利用漏电介质模型模拟均匀静电场,研究了电场强度、液滴粒径、液滴表面间距和液滴相对位置(液滴中心连线与电场强度...为了探究运行参数对分散相液滴的运动、聚并过程的影响,采用VOF(volume of fluid)方法捕捉分散相与连续相的流体间界面,利用漏电介质模型模拟均匀静电场,研究了电场强度、液滴粒径、液滴表面间距和液滴相对位置(液滴中心连线与电场强度方向夹角)对处于均匀电场中离散相多液滴聚并行为的影响,通过理论分析了液滴聚并过程影响因素,并与数值计算结论进行了对比.结果表明:分散相液滴聚并效率与电场强度、液滴粒径比、液滴表面间距以及液滴的相对位置有关;随着电场强度的增加,液滴的聚并效率显著增强;随着液滴表面间距以及液滴相对角度的增大,聚并效率有所降低;液滴粒径比对聚并效率亦产生影响,当液滴粒径差距较大时,液滴的聚并效率有所降低;电场强度对聚并过程的影响较为复杂,当外加电场强度持续增大时,液滴难以发生聚并,液滴被拉长后产生破碎或者弹开现象,存在阻碍液滴聚并的临界场强.展开更多
A resident time model is proposed to evaluate the performance of agitated extraction columns. In this model, the resident time of dispersed drops is simulated with the discrete phase modeling, where the continuous pha...A resident time model is proposed to evaluate the performance of agitated extraction columns. In this model, the resident time of dispersed drops is simulated with the discrete phase modeling, where the continuous phase and the dispersed phase （drops） are described by the single-phase Navier-Stokes （turbulence） model and Lagrangian model, respectively. The interaction of dispersed phase and continuous phase is neglected for the low concentration of drop in the cases studied. The statistical parameters of drops （the average resident time and standard deviation） under different operation conditions are computed for four columns. The relation of the above statistical parameters with the performance of columns is discussed and the criterions for an optimal compartment are outlined. Our results indicate that the resident time model is useful to evaluate the performance and optimize the design of extraction columns.展开更多
In this paper,shorter residence time（a few minutes）with high yield in the trickle bed process for per- acetic acid synthesis by acetaldehyde liquid phase oxidation can be realized on the selected packing material SA...In this paper,shorter residence time（a few minutes）with high yield in the trickle bed process for per- acetic acid synthesis by acetaldehyde liquid phase oxidation can be realized on the selected packing material SA-5118.For acetaldehyde in acetone with ferric ion as catalyst,the optimized process conditions were presented. The main factors influencing the yield,selectivity and conversion are residence time,temperature and acetaldehyde concentration,respectively.The temperature range checked is from 30 to 65℃.High yield of 81.53%with high se- lectivity of 91.84%can be obtained at higher temperature of 55℃when the residence time is 5.5min and the acet- aldehyde concentration is 9.85%（by mass）.And there is a critical acetaldehyde concentration point（Cccp）between 18%and 19.5%（by mass）.At temperature less than 55℃,the highest yield to peracetic acid at each temperature level increases with temperature when the acetaldehyde concentration is below Cccp and decreases with temperature when the acetaldehyde concentration is above Cccp.展开更多
Modelling and simulations are conducted on velocity slip and interfacial momentum transfer for supersonic two-pha.se (gas-droplet) flow in the transient section inside and outside a Laval jet(LJ). The initial velocity...Modelling and simulations are conducted on velocity slip and interfacial momentum transfer for supersonic two-pha.se (gas-droplet) flow in the transient section inside and outside a Laval jet(LJ). The initial velocity slip between gas and droplets causes an interfacial momentum transfer flux as high as (2.0-5.0) x 104 Pa. The relaxation time corresponding to this transient process is in the range of 0.015-0.090ms for the two-phase flow formed inside the LJ and less than 0.5ms outside the LJ. It demonstrates the unique performance of this system for application to fast chemical reactions using electrically active media with a lifetime in the order of 1 ms. Through the simulations of the transient processes with initial Mach number Mg from 2.783 to 4.194 at different axial positions inside the LJ, it is found that Mg has the strongest effect on the process. The momentum flux increases as the Mach number decreases. Due to compression by the shock wave at the end of the LJ, the flow pattern becomes two dimensional and viscous outside the LJ. Laser Doppler velocirneter (LDV) measurements of droplet velocities outside the LJ are in reasonably good agreement with the results of the simulation.展开更多
The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in t...The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model （FRDM）. The single-particle spectra of nuclei in ^295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square （rms） radii of proton, neutron and matter distributions change slowly from ^283112 to ^295118 but dramatically from ^279110 to ^283112, which may be due to the subshell closure at Z = 110 in ^279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model （GLDM）, and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z=118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.展开更多
Numerical simulation of transient mass transfer to a single dropcontrolled by the internal resistance or by the resistance in bothphases was mathematically formulated and simulated in aboundary-fitted orthogonal coord...Numerical simulation of transient mass transfer to a single dropcontrolled by the internal resistance or by the resistance in bothphases was mathematically formulated and simulated in aboundary-fitted orthogonal coordinate system. The simulated resultson the transient mass transfer dominated by the internal resistanceare in good agreement with the Newman and Kronig-Brink models fordrops with low Reynolds number. When the drop Reynolds number is upto 200, the mass transfer coefficient from numerical simulation isvery low as compared with The Handlos-Baron model.展开更多
The process in the countercurrent humidifier of HAT cycle involves the evaporation of atomized liquids in a turbulent environment. To allow an optimization of such process and provide data for the validation of numeri...The process in the countercurrent humidifier of HAT cycle involves the evaporation of atomized liquids in a turbulent environment. To allow an optimization of such process and provide data for the validation of numerical calculation, the spray evaporation in a countercurrent air stream was studied experimentally. Measurements were taken for different flow parameters, such as airflow rate and liquid flow rate in order to provide reliable data. Phase-Doppler anemometry (PDA) was applied to obtain the spatial change of the droplet size spectrum in the flow field and to measure droplet size-velocity correlations. These local measured profiles of droplet mean velocities, velocity fluctuations and droplet mean diameters were obtained by averaging over all droplet size classes. Moreover, DualPDA signal processing allows accurate determination of the droplet mass flux and local concentration, from which the global evaporation rates could also be determined. These local temperature profiles were measured using the thermocouple and acquired by data acquisition system based on virtual instrument (VI) technology.展开更多
Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） ...Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.展开更多
The rebound behaviors of droplets impacting on a self-fabricated superhydrophobic brass surface （WCA=I64.5°） were ob- served and studied by using high-speed-camera. In accordance with energy conversion, theoret...The rebound behaviors of droplets impacting on a self-fabricated superhydrophobic brass surface （WCA=I64.5°） were ob- served and studied by using high-speed-camera. In accordance with energy conversion, theoretical analysis of different behav- iors and rebound mechanism were given. At lower velocities, three behaviors in different velocity ranges were observed： par- tial rebounding, entire rebounding and ejecting during rebounding. At higher velocities, such two behaviors as rebound after splashing and rebound, ejecting after splashing, occurred alternately and exhibited certain periodicity. A function to predict the critical impact velocity is derived from energy conservation condition, and the prediction values tally with the experimental values, with the maximum relative error about 14%.展开更多
文摘为了探究运行参数对分散相液滴的运动、聚并过程的影响,采用VOF(volume of fluid)方法捕捉分散相与连续相的流体间界面,利用漏电介质模型模拟均匀静电场,研究了电场强度、液滴粒径、液滴表面间距和液滴相对位置(液滴中心连线与电场强度方向夹角)对处于均匀电场中离散相多液滴聚并行为的影响,通过理论分析了液滴聚并过程影响因素,并与数值计算结论进行了对比.结果表明:分散相液滴聚并效率与电场强度、液滴粒径比、液滴表面间距以及液滴的相对位置有关;随着电场强度的增加,液滴的聚并效率显著增强;随着液滴表面间距以及液滴相对角度的增大,聚并效率有所降低;液滴粒径比对聚并效率亦产生影响,当液滴粒径差距较大时,液滴的聚并效率有所降低;电场强度对聚并过程的影响较为复杂,当外加电场强度持续增大时,液滴难以发生聚并,液滴被拉长后产生破碎或者弹开现象,存在阻碍液滴聚并的临界场强.
基金Supported by the National Natural Science Foundation of China (No. 20376053).
文摘A resident time model is proposed to evaluate the performance of agitated extraction columns. In this model, the resident time of dispersed drops is simulated with the discrete phase modeling, where the continuous phase and the dispersed phase （drops） are described by the single-phase Navier-Stokes （turbulence） model and Lagrangian model, respectively. The interaction of dispersed phase and continuous phase is neglected for the low concentration of drop in the cases studied. The statistical parameters of drops （the average resident time and standard deviation） under different operation conditions are computed for four columns. The relation of the above statistical parameters with the performance of columns is discussed and the criterions for an optimal compartment are outlined. Our results indicate that the resident time model is useful to evaluate the performance and optimize the design of extraction columns.
文摘In this paper,shorter residence time（a few minutes）with high yield in the trickle bed process for per- acetic acid synthesis by acetaldehyde liquid phase oxidation can be realized on the selected packing material SA-5118.For acetaldehyde in acetone with ferric ion as catalyst,the optimized process conditions were presented. The main factors influencing the yield,selectivity and conversion are residence time,temperature and acetaldehyde concentration,respectively.The temperature range checked is from 30 to 65℃.High yield of 81.53%with high se- lectivity of 91.84%can be obtained at higher temperature of 55℃when the residence time is 5.5min and the acet- aldehyde concentration is 9.85%（by mass）.And there is a critical acetaldehyde concentration point（Cccp）between 18%and 19.5%（by mass）.At temperature less than 55℃,the highest yield to peracetic acid at each temperature level increases with temperature when the acetaldehyde concentration is below Cccp and decreases with temperature when the acetaldehyde concentration is above Cccp.
基金Supported by the National Natural Science Foundation of China (No. 29876022) and Grant of State Key Laboratory of High Speed Hydrodynamics (No. 2007).
文摘Modelling and simulations are conducted on velocity slip and interfacial momentum transfer for supersonic two-pha.se (gas-droplet) flow in the transient section inside and outside a Laval jet(LJ). The initial velocity slip between gas and droplets causes an interfacial momentum transfer flux as high as (2.0-5.0) x 104 Pa. The relaxation time corresponding to this transient process is in the range of 0.015-0.090ms for the two-phase flow formed inside the LJ and less than 0.5ms outside the LJ. It demonstrates the unique performance of this system for application to fast chemical reactions using electrically active media with a lifetime in the order of 1 ms. Through the simulations of the transient processes with initial Mach number Mg from 2.783 to 4.194 at different axial positions inside the LJ, it is found that Mg has the strongest effect on the process. The momentum flux increases as the Mach number decreases. Due to compression by the shock wave at the end of the LJ, the flow pattern becomes two dimensional and viscous outside the LJ. Laser Doppler velocirneter (LDV) measurements of droplet velocities outside the LJ are in reasonably good agreement with the results of the simulation.
基金Supported by the Natural Science Foundation of China under Grant Nos.10775061,10505016,10575119,and 10805016the CAS Knowledge Innovation Project under Grant No.KJCX-SYW-N02the Major State Basic Research Developing Program of China under Grant No.2007CB815004
文摘The properties of nuclei belonging to the α-decay chain of superheavy element ^295118 have been studied in the framework of axially deformed relativistic mean field （RMF） theory with the parameter set of NL-Z2 in the blocked BCS approximation. Some ground state properties such as binding energies, deformations, and α-decay energies Qα have been obtained and agree well with those from finite-range droplet model （FRDM）. The single-particle spectra of nuclei in ^295118 α-decay chain show that the shell gaps present obviously nucleon number dependence. The root-mean-square （rms） radii of proton, neutron and matter distributions change slowly from ^283112 to ^295118 but dramatically from ^279110 to ^283112, which may be due to the subshell closure at Z = 110 in ^279110. The α-decay half-lives in 295118 decay chain are evaluated by employing the cluster model and the generalized liquid drop model （GLDM）, and the overall agreement is found when they are compared with the known experimental data. The α-decay lifetimes obtained from the cluster model are slightly larger than those of GLDM ones. Finally, we predict the α-decay half-lives of Z=118, 116, 114, 112 isotopes using the cluster model and GLDM, which also indicate these two models can corroborate each other in studies on superheavy nuclei. The results from GLDM are always lower than those obtained from the cluster model.
基金Supported by the National Natural Science Foundation of China (No. 29792074, No. 29836130} and SINOPEC.
文摘Numerical simulation of transient mass transfer to a single dropcontrolled by the internal resistance or by the resistance in bothphases was mathematically formulated and simulated in aboundary-fitted orthogonal coordinate system. The simulated resultson the transient mass transfer dominated by the internal resistanceare in good agreement with the Newman and Kronig-Brink models fordrops with low Reynolds number. When the drop Reynolds number is upto 200, the mass transfer coefficient from numerical simulation isvery low as compared with The Handlos-Baron model.
基金973 Key Develop Projectof the Ministry ofScience and Technology of China (No.G19990 2 2 3 0 3 )
文摘The process in the countercurrent humidifier of HAT cycle involves the evaporation of atomized liquids in a turbulent environment. To allow an optimization of such process and provide data for the validation of numerical calculation, the spray evaporation in a countercurrent air stream was studied experimentally. Measurements were taken for different flow parameters, such as airflow rate and liquid flow rate in order to provide reliable data. Phase-Doppler anemometry (PDA) was applied to obtain the spatial change of the droplet size spectrum in the flow field and to measure droplet size-velocity correlations. These local measured profiles of droplet mean velocities, velocity fluctuations and droplet mean diameters were obtained by averaging over all droplet size classes. Moreover, DualPDA signal processing allows accurate determination of the droplet mass flux and local concentration, from which the global evaporation rates could also be determined. These local temperature profiles were measured using the thermocouple and acquired by data acquisition system based on virtual instrument (VI) technology.
文摘Characteristics of thermal-hydraulic interaction of LBE （45w%Pb-55w%Bi） and lead with subcooled water in pool water were investigated experimentally. Two kinds of interaction zones （deformation and fragmentation） and three kinds of interaction zones （solidification, deformation and fragmentation） were observed during LBE droplet/water interaction and lead droplet/water interaction, respectively. The fragmentation zone （FZ） could be identified exactly by two border lines： spontaneous nucleation temperature and minimum film boiling temperature. Within fragmentation zone, 10% to 35% tiny debris （diameter 〈 1 mm） of LBE and 5 to 8 kPa peak pressure generated with increasing the LBE temperature and no effect with increasing the subcooling of water. Only 2%-4% tiny debris （diameter 〈 1 mm） of lead and 2 kPa peak pressure generated regardless of lead and water temperature.
基金supported by The National Natural Science Foundation of China (Grant No.51109178)Science and Technology Innovation Foundation of NWPU (Grant No.JC20120218)
文摘The rebound behaviors of droplets impacting on a self-fabricated superhydrophobic brass surface （WCA=I64.5°） were ob- served and studied by using high-speed-camera. In accordance with energy conversion, theoretical analysis of different behav- iors and rebound mechanism were given. At lower velocities, three behaviors in different velocity ranges were observed： par- tial rebounding, entire rebounding and ejecting during rebounding. At higher velocities, such two behaviors as rebound after splashing and rebound, ejecting after splashing, occurred alternately and exhibited certain periodicity. A function to predict the critical impact velocity is derived from energy conservation condition, and the prediction values tally with the experimental values, with the maximum relative error about 14%.
