To determine and calculate the stable fluidization zone in a magnetically fluidized bed, the fluidization characteristics of magnetic particles are investigated. Four kinds of magnetic particles with different average...To determine and calculate the stable fluidization zone in a magnetically fluidized bed, the fluidization characteristics of magnetic particles are investigated. Four kinds of magnetic particles with different average diameters, ranging from 231 to 512 μm, are fluidized in the presence of magnetic fields with specified values of the intensity in the range of zero to 7330 A/m, and the particle fluidization curves are plotted. For marking the stable fluidization zone in the curves, the minimum bubbling velocities of particles are measured by the pressure-drop fluctuation. Based on the fluidization curves, the influences of the average particle diameter and magnetic field intensity on the zone are analyzed and discussed. A correlation to determine the stable fluidization zone is derived from the experimental data, using three dimensionless numbers, i. e., the ratio of magnetic potential to gravity potential, the Reynolds number and the Archimedes number. Compared with available data reported, it is shown that the correlation is more simplified to predict relative parameters for the bed operating in the state of stable fluidization under reasonable conditions.展开更多
As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating...As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating discs,forming zigzag channels for liquid-gas flow and mass transfer.As in RPBs,some hydrodynamic behavior in RZB is interesting but no satisfactory explanation.In this study,the experiments were carried on in a RZB unit with a rotor of 600 mm in diameter using air-water system.The gas pressure drop and power consumption were measured with two types of rotating baffle for RZB rotors,one with perforations and another with shutter openings. The circumferential velocities of gas were measured with a five-hole Pitot probe.The pressure drop decreased rapidly when the liquid was introduced to the rotor,because the circumferential velocity of the liquid droplets was lower than that of the gas,reducing the circumferential velocity of gas and the centrifugal pressure drop.The power consumption decreased first when the gas entered the RZB rotor,because the gas with higher circumferential velocity facilitates the rotation of baffles.展开更多
Alumina （MMAD： 32.45μm） was used to study dust cake formation in fiber filter at steady-state operation. Cake vertical profile along filter medium versus filtration velocity （ranging from 3 to 7cm/s）, particle c...Alumina （MMAD： 32.45μm） was used to study dust cake formation in fiber filter at steady-state operation. Cake vertical profile along filter medium versus filtration velocity （ranging from 3 to 7cm/s）, particle concentration （ranging from 40 to 120g/m^3） and particle areal mass to filter （ranging from 0.57 to 2.86 kg/m^2）, was researched by experiments and modeling. The filtration was carried through by a plane filter media （Material： Terylene felt, Thickness： 1.8mm） covered on a framework which was fixed in a filter. During filtration, the cake thickness was measured up and down by a mobile microscope and a camera controlled by a PC. The results showed that the cake vertical profile accord with a peak function. The peak amplitude A, center displacement xc, the shape parameters W of the peak function was greatly depended on filtration velocity and particle areal mass to filter, whereas slightly on particle concentration. The relationships between the three coefficients （peak amplitude A, center displacement xc, the shape parameters W） and filtration velocity, areal mass to filter, particle concentration were associated as equations, based on which pressure drop model was deduced. The peak function and pressure drop model were verified with experimental data.展开更多
Vortex flow is applied to a cyclone dust collector, a vortex combustion chamber, and a vortex diode for vortex control. In order to apply the vortex flow to the industries, it is necessary to keep the stable flow cond...Vortex flow is applied to a cyclone dust collector, a vortex combustion chamber, and a vortex diode for vortex control. In order to apply the vortex flow to the industries, it is necessary to keep the stable flow condition and to estimate the response time of the transient flow process and also the intensity of the vortex flow. For control vortex flow, two types of vortex chamber with two inlet pipes were designed. One of them is to promote the vortex flow named as Co-Rotating Flow System and another one is to hinder the vortex flow named as Counter-Rotating Flow System. The pressure drops and the velocity distributions were measured for these vortex chambers. The estimation of the tangential velocity by the application of the angular momentum flux is compared with the measured velocity by a cylindrical Pitot-tube. The characteristics of the total pressure drop could be explained by introducing the circulation.展开更多
基金The National Natural Science Foundation of China(No50576013)
文摘To determine and calculate the stable fluidization zone in a magnetically fluidized bed, the fluidization characteristics of magnetic particles are investigated. Four kinds of magnetic particles with different average diameters, ranging from 231 to 512 μm, are fluidized in the presence of magnetic fields with specified values of the intensity in the range of zero to 7330 A/m, and the particle fluidization curves are plotted. For marking the stable fluidization zone in the curves, the minimum bubbling velocities of particles are measured by the pressure-drop fluctuation. Based on the fluidization curves, the influences of the average particle diameter and magnetic field intensity on the zone are analyzed and discussed. A correlation to determine the stable fluidization zone is derived from the experimental data, using three dimensionless numbers, i. e., the ratio of magnetic potential to gravity potential, the Reynolds number and the Archimedes number. Compared with available data reported, it is shown that the correlation is more simplified to predict relative parameters for the bed operating in the state of stable fluidization under reasonable conditions.
基金Supported by the Natural Science Foundation of Zhejiang Province（Y406239）
文摘As a high gravity(HIGEE)unit,the rotating packed bed(RPB)uses centrifugal force to intensify mass transfer.Zigzag rotating bed(RZB)is a new type of HIGEE unit.The rotor of RZB consists of stationary discs and rotating discs,forming zigzag channels for liquid-gas flow and mass transfer.As in RPBs,some hydrodynamic behavior in RZB is interesting but no satisfactory explanation.In this study,the experiments were carried on in a RZB unit with a rotor of 600 mm in diameter using air-water system.The gas pressure drop and power consumption were measured with two types of rotating baffle for RZB rotors,one with perforations and another with shutter openings. The circumferential velocities of gas were measured with a five-hole Pitot probe.The pressure drop decreased rapidly when the liquid was introduced to the rotor,because the circumferential velocity of the liquid droplets was lower than that of the gas,reducing the circumferential velocity of gas and the centrifugal pressure drop.The power consumption decreased first when the gas entered the RZB rotor,because the gas with higher circumferential velocity facilitates the rotation of baffles.
文摘Alumina （MMAD： 32.45μm） was used to study dust cake formation in fiber filter at steady-state operation. Cake vertical profile along filter medium versus filtration velocity （ranging from 3 to 7cm/s）, particle concentration （ranging from 40 to 120g/m^3） and particle areal mass to filter （ranging from 0.57 to 2.86 kg/m^2）, was researched by experiments and modeling. The filtration was carried through by a plane filter media （Material： Terylene felt, Thickness： 1.8mm） covered on a framework which was fixed in a filter. During filtration, the cake thickness was measured up and down by a mobile microscope and a camera controlled by a PC. The results showed that the cake vertical profile accord with a peak function. The peak amplitude A, center displacement xc, the shape parameters W of the peak function was greatly depended on filtration velocity and particle areal mass to filter, whereas slightly on particle concentration. The relationships between the three coefficients （peak amplitude A, center displacement xc, the shape parameters W） and filtration velocity, areal mass to filter, particle concentration were associated as equations, based on which pressure drop model was deduced. The peak function and pressure drop model were verified with experimental data.
文摘Vortex flow is applied to a cyclone dust collector, a vortex combustion chamber, and a vortex diode for vortex control. In order to apply the vortex flow to the industries, it is necessary to keep the stable flow condition and to estimate the response time of the transient flow process and also the intensity of the vortex flow. For control vortex flow, two types of vortex chamber with two inlet pipes were designed. One of them is to promote the vortex flow named as Co-Rotating Flow System and another one is to hinder the vortex flow named as Counter-Rotating Flow System. The pressure drops and the velocity distributions were measured for these vortex chambers. The estimation of the tangential velocity by the application of the angular momentum flux is compared with the measured velocity by a cylindrical Pitot-tube. The characteristics of the total pressure drop could be explained by introducing the circulation.
