高黏度液体错流旋转微滤实验研究

Experimental investigation of the microfiltration （MF） using a revolving cross-flow membrane filter was performed under the condition of constant pressure difference, and different flat membranes made of polyvinylidene fluoride （PVDF, 0.1 μm）, cellulose acetate （CA, 0.22 μm）, sulfonated polyethersulfone （SPES, 0.22 μm） and polyamide （PA, 0.45 μm）, respectively, were used in filtration experiments. The dependence of the filtrate mass of the cross-flow MF on time was measured on-line. The experimental results showed that the effect of the cross-flow on high viscosity medium was more significant than that on the low viscosity one.     

Removal of sodium dodecyl benzene sulfonate and phenol from water by a combined PAC adsorption and cross‐flow microfiltration process

The removal of sodium dodecyl benzene sulfonate (SDBS) and phenol from water by a combined process of PAC (powdered activated carbon) adsorption and cross‐flow microfiltration (PAC–MF) was investigated. Batch PAC adsorption studies were made to obtain the isotherm data. The PAC–MF experiments were performed as a function of PAC dose (0.2–1.0 g dm^?3), solution pH (2.5–11.2), transmembrane pressure (10–30 psi), and cross‐flow velocity (4.7–8.3 mm s^?1). A compromise between removal efficiency of the organics and the permeate flux in the PAC–MF process was needed to select a suitable PAC dose. The role of pH in the PAC–MF process mainly depended on the acid–base nature of the organics being removed. A comparison of PAC–MF and fixed bed processes was also made, and the application potential of this PAC–MF process for continuous removal of relatively high‐molar‐mass organics such as SDBS from waste effluents was demonstrated. Copyright © 2004 Society of Chemical Industry     

Effect of flocculation and/or adsorption as pretreatment on thecritical flux of crossflow microfiltration

This study aims at identifying the effect of pretreatment such as flocculation and/or adsorption on the performance of crossflow microfiltration (CFMF). CFMF performance was studied in terms of critical flux. The results indicated that: (1) flocculation alone as a pretreatment could effectively remove the large molecular weight organic matter from 30,000 to 60,000 Daltons; (2) flocculation, together with adsorption as a pretreatment to CFMF, could remove both large and small molecular weight organics; (3) flocculation as a pretreatment was significantly better than adsorption in improving the critical flux; (4) critical flux increased from 100 L/m².h to 520 L/m².h when flocculation-adsorption was applied. The critical flux in long-term experiments was the same as that of the short-term experiments. However, the critical flux slightly decreased (5%) in long-term experiments compared to short-term operation with flocculation and adsorption as a pretreatment.     

Threshold flux in fouling of OF membranes by colloidal iron

Fouling of 50 kDa MWCO OF membranes by iron colloid solutions was studied under constant pressure conditions and constant flux conditions at pH 5 and 7 and at various iron concentrations. By using measurements of both deposit density and changes in the transmembrane zeta potential, threshold fluxes were found that were significantly lower than the critical flux based on the increase in membrane resistance. Results are consistent with the initial phase of fouling involving pore blockage followed by cake filtration-like behavior. The dependence of fouling rate on iron colloid concentration can best be understood by realizing that only a small fraction of the iron colloid is of a size that contributes to fouling.     

假塑性高粘流体垂直管内流动沸腾CHF

以ＣＭＣ水溶液为介质，对高粘幂律流体进行了垂直管内流动沸腾超临界热流的研究。测定了３１组临界热流数据，建立了临界热流关联式。计算值与实验值的偏差为１７．７％。     

Investigation of reacting flow fields in miscible viscous fingering by a novel experimental method

The reacting flow fields in reactive miscible viscous fingering in a Hele‐Shaw cell studied by Nagatsu and Ueda had not been completely elucidated, mainly because one cannot exactly recognize where and when the reaction takes place in the reactive fingering pattern. We developed a novel experimental method that allowed us to identify the reaction region in the fingering pattern employed in the previous studies. The novel method involves switching of the less‐viscous liquid injected in both the nonreactive and reactive experiments. By using the novel method, we succeeded in showing how the reaction region in the fingering pattern was affected by the initial reactant concentrations, the Péclet number, and time. We propose physical models of the reacting flow field in the cell's gap direction that can explain the obtained experimental results. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

The effects of capillary forces on the flow properties of glass particle suspensions in mineral oil

The effect of water on the flow behavior of glass microspheres dispersed in mineral oil was investigated for various levels of water, particle volume fractions, and particle sizes. The addition of small amounts of water leads to large increases in viscosity due to the formation of water bridges between particles that give rise to capillary forces between the particles. The capillary forces between the particles also make the flow profile highly shear‐thinning across the range of particle volume fractions that were studied (0.10 to 0.25). The presence of water leads to a significant effect of particle size, and the viscosity of dispersion goes through a maximum as the amount of water is increased. Two hydrophobic surfactants, Span 80 and Arquad 2HT, were found to reduce the viscosity of the dispersions with added water, but the mechanism and extent of viscosity reduction differed. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

旋转管式微滤器中流体流动对过滤通量的影响

为讨论膜器环隙内流体流动对过滤通量的影响,运用了纳维—斯托克斯方程、连续性方程、达西定律等,并结合稳定性理论,分别对主流体为去离子水和悬浮液的情况下环隙内流体的运动规律进行了分析。对于主流体为去离子水的情况,建立了过滤通量与膜器进出口压力降的关系,并与Belfort的实验数据进行了比较。结果证明当主流体为去离子水时(即无滤饼生成的理想情况下),流体旋转所产生的离心力对微滤推动力有削弱作用,当内膜管转速较小时,流体流动方式对过滤通量几乎无影响。对于悬浮液,由内膜管旋转所形成的剪切力对减少滤饼形成的作用甚微,而Taylor涡的形成是强化微滤的主要原因。最后提出了内膜管旋转管式膜器优化设计的新思想。     

Uniform flux heat transfer in concentric laminar flow of two immiscible liquids

The energy equation was solved exactly for fully developed steady laminar flow in a circular pipe of two immncible Newton liquids with a concentric cylindrical interface between them, assuming invariant physical properties of the liquids, uniform heat flux at the wall and fully developed temperature profiles. It is shown that, even if the viscosity of the annular liquid is orders of magnitude smaller than that of the core liquid, the improvement in heat transfer to the core liquid by infection of the annular liquid cannot exceed a factor of 1 8     

Characterization of liquid‐liquid flows in horizontal pipes

Diverse flow regimes have been encountered in liquid‐liquid flows. Some degree of consistency in the observed flow patterns is shown in reported studies, while inconsistency exits when physical properties of the two phases concerned are wide enough. An attempt was made in this study to investigate the mechanisms behind flow patterns of liquid‐liquid flows in horizontal pipes. A literature review on flow patterns of liquid‐liquid flows in horizontal pipes was conducted. The ratio of the gravitational force to viscous force was proposed to characterize liquid‐liquid flows in horizontal pipes into gravitational force dominant, viscous force dominant, and gravitational force and viscous force comparable flow featured with different basic flow regimes. Comparisons of the proposed characterization criterion with the literature data show good agreement. © 2016 American Institute of Chemical Engineers AIChE J, 63: 1132–1143, 2017     

Drag on chains and agglomerates of spheres in viscous newtonian and power law fluids

New experimental data on the free settling velocity of straight chains (up to twenty spheres) and planar clusters of touching spheres in Newionian and power law media are reported. The results embrace the following ranges of conditions: 0.65 ≤ n ≤ 1; Re < - 2.5 and 1.22 < m < 48.87 Pa·sⁿ. The straight chain drag measurements are in line with theoretical predictions for Newtonian fluids. The present results in power law fluids seem to suggest that it is possible to express the drag on a straight chain of spheres in terms of that on a single sphere of equal volume. Limited results with planar clusters are satisfactorily correlated using a volume equivalent sphere diameter.     

A model of steady viscous flow of a micropolar fluid driven by injection or suction between a porous disk and a non‐porous disk using a novel numerical technique

In this study, we solve the problem of steady viscous flow of a micropolar fluid driven by injection between two porous disks using novel spectral modification of the homotopy analysis method (SHAM). The effects of Reynold's number (Re), and the micropolar parameters (c₁, c₂, c₃) on the velocity profiles and microrotation are shown through tables and graphed and then discussed.     

高颗粒通量循环流化床的构型作用

In order to achieve high solids circulation rate (G_s),an idea of coupling a moving bed to the bottom section of the riser of a circulating fluidized bed (CFB) was proposed and tested.The results from the preliminary study demonstrated that the solids circulation rate in the new-structure bed approached 370 kg·m^-2·s^-1 at superficial gas velocities around 10.5 m·s^-1 for sand particles with an average Sauter mean size of 378 μm.This study was devoted to further justifying the effects of the coupled moving bed by performing comparative studies in two CFBs with conventional configurations.It was shown that the pressure at the riser bottom and the realized solid circulation rate were only about 15 kPa and 230 kg·m^-2·s^-1 in the two conventionally configured CFBs,obviously lower than 25 kPa and 370 kg·m^-2·s^-1 in the moving bed coupled CFB.These verified that the coupled moving bed increased the force driving particles form the particle recycling side into the riser.The study further tested the effect of a few specially designed riser exit configurations,revealing that a smooth riser exit could facilitate solids circulation to increase the solids circulation rate.     

低雷诺数下气固两相中浓稀相界面对微尺度曳力的影响及建模

采用具有二阶精度的浸没边界-格子玻尔兹曼法对低雷诺数下流体流经不同颗粒聚团结构的过程进行了解析到颗粒表面的直接数值模拟(PR-DNS)。结果显示在颗粒聚团表面的浓稀相界面处,传统的微观均匀BVK曳力模型[AIChE Journal, 2007, 53(2): 489-501]的预测结果与PR-DNS结果有明显的差别;同时文献中所构建的考虑界面影响的微观曳力模型(Int. J. Multiphase Flow, 2020, 128: 103266)也无法准确预测稀相固含率不为0的情况。因此,本工作提出了一种将界面附近网格分解求取曳力的方法。通过与不同颗粒聚团结构的PR-DNS结果及其他曳力模型预测结果对比发现,新模型不但在稀相固含率趋近于0时与文献中模型具有相近的预测能力,且在稀相固含率不为0时,具有明显优于文献模型的相关系数及拟合优度。