Mathematic Model of Unsteady Penetration Mass Transfer in Randomly Packed Hollow Fiber Membrane Module

Based on the membrane-based absorption experiment of CO2 into water, shell-side flow distribution and mass transfer in a randomly packed hollow fiber module have been analyzed using subchannel model and unsteady penetration mass transfer theory. The cross section of module is subdivided into many small cells which contains only one hollow-fiber. The cross sectional area distribution of these cells is presented by the normal probability density distribution function. It has been obtained that there was a most serious non-ideal flow in shell side at moderate mean packing density, and the large amount of fluid flowed and transferred mass through a small number of large voids. Thus mass transfer process is dominated by the fluid through the larger void area. The mass transfer process in each cell is described by the unsteady penetration theory. The overall mass transfer coefficient equals to the probability addition of the mean mass transfer coefficient in each cell. The comparisons of the values calculated by the model established with the empirical correlations and the experimental data of this work have been done.The predicted overall mass transfer coefficients are in good agreement with experimental data.

CFD simulation of flow field and resistance in a 19-core tandem ceramic membrane module

CFD simulation of the permeation process of a 19-core tandem ceramic membrane module was established to investigate flow field and resistance and its change in permeate flux to the membrane element position and the channel of each membrane element.The results show that when the volume flow rate changes from26 m3·h-1 to 89 m3·h-1,the resistance of each part of the membrane module increases gradually.The increase in resistance loss in the membrane element is faster than the plates and the bell mouths.In a single ceramic membrane module,the maximum difference in flow rate of each membrane tube is 7.23%.In a single membrane tube,the outer ring channels 3–5,3–6,3–7,3–8 are relatively slow.The maximum mass flow deviation from the mean is 2.7%.This work helps to clarify the flow mechanism within the modules,optimize the structure of the equipment and provide a reliable basis for the improvement of industrial ceramic membrane modules.

Evaluation of hollow fiber T-type zeolite membrane modules for ethanol dehydration

This work presents the design of hollow fiber T-type zeolite membrane modules with different geometric configurations. The module performances were evaluated by pervaporation dehydration of ethanol/water mixtures. Strong concentration polarization was found for the modules with big membrane bundles. The concentration polarization was enhanced at high temperature due to the higher water permeation flux. The increase of feed flow could improve water permeation flux for the membrane modules with small membrane bundle.Computational fluid dynamics was used to visualize the flow field distribution inside of the modules with different configurations. The membrane module with seven bundles exhibited highest separation efficiency due to the uniform distribution of flow rate. The packing density could be 10 times higher than that of the tubular membrane module. The hollow fiber membrane module exhibited good stability for ethanol dehydration.

Modeling of Mass Transfer in Cavity Limited by a Semi Permeable Membrane （Simulation of Spiral Wound Module）

The reverse osmosis process has been applied in large industrial fields （water treatment, food industry, biotechnology, and ect.）. Despite, this progress more investigation are required to optimize the reverse osmosis process. The present paper deals the modeling of mass transfer in a cavity limited by a semi-permeable membrane. Mass conservation and momentum balances are developed, dimensionless and control volume method has been applied. The velocity and concentration profiles versus the Reynolds number and Sherwood are studied. The results show that the permeability of the membrane decreases as function of the transversal （radial） component of the velocity. The axial （tangential） component of the velocity presents a good stability along the thickness of the cavity; this phenomenon can be attributed to the zero gradient of the tangential velocity. These preliminary results show that the phenomenon of the concentration polarization affects the mass transfer coefficient in a channel. Current study has considered the cavity without a promoter of the turbulence; whereas, the design of the spacer has an important role on mass transfer coefficient in the reverse osmosis module. Our next interest is the integration of the spacer in the cavity, and the study of the effect of its design on the concentration and velocity profiles and the mass transfer coefficient through the reverse osmosis membrane.

Energy Absorption by the Membrane Rafts in the Modulated Electro-Hyperthermia (mEHT)

Aim: Heating by nanoparticles, which are located in the tissue to be treated, is a well-recognized method in hyperthermic oncology. Our objective is to investigate selective, nanoscopic heating without concentrating extra artificial nanoparticles. We have in silico calculation to study the heating of the transmembrane protein clusters (rafts) on cell-membrane. The transmembrane protein domains have significantly higher dielectric constant than their lipid neighborhood in the membrane. This difference causes a local gradient in the Specific Absorption Rate (SAR), which could be a factor of heating of the membranes locally, as well as exciting the receptors for various signal transduction in the cells. We suppose that this process determines the observed cellular effects of modulated electro-hyperthermia (mEHT, trade-name: oncothermia). Materials and Methods: In silico models with highly specialized software (Computer Simulation Technology (CST), Darmstadt, Germany) were performed visualizing the selectivity for the membrane domains. Local raft models were created to simulate the electromagnetic (EM) effect of a 13.56 MHz excitation between two perfect electrical conductor plates, simulating the equipotential conditions of the sides of the membrane in the vicinity of the raft. The simulations were performed with near-field (EQS) solver of CST. The electric field, current density, and electric loss density were monitored by the simulations. The applied material properties and parameters refer to the recent literature. Results: In silico models show ten times higher energy-absorption of the transmembrane domains than that of its lipid-membrane surrounding, and intra- and extracellular neighborhood. Depending on the size, orientation, and location of the membrane rafts, the value of SAR varies, but we use only two simplified models to see the absorption properties. Taking into account the characteristics of the EM field effects we showed that the selective energy-absorption increased further by the cell-cell interactions. The model-calculation could confirm the opportunity of the local membrane heating. Conclusion: Our results indicate the heating in nanoscopic range with energy-absorption by the transmembrane proteins. The heated protein-clusters (membrane rafts) are used the same way as the artificial nanoparticles, while these absorbers are natural parts of the biological system.

Cell Membrane Coating Technology:A Promising Strategy for Biomedical Applications

Cell membrane coating technology is an approach to the biomimetic replication of cell membrane properties,and is an active area of ongoing research readily applicable to nanoscale biomedicine.Nanoparticles(NPs)coated with cell membranes offer an opportunity to unite natural cell membrane properties with those of the artificial inner core material.The coated NPs not only increase their biocompatibility but also achieve effective and extended circulation in vivo,allowing for the execution of targeted functions.Although cell membrane-coated NPs offer clear advantages,much work remains before they can be applied in clinical practice.In this review,we first provide a comprehensive overview of the theory of cell membrane coating technology,followed by a summary of the existing preparation and characterization techniques.Next,we focus on the functions and applications of various cell membrane types.In addition,we collate model drugs used in cell membrane coating technology,and review the patent applications related to this technology from the past 10 years.Finally,we survey future challenges and trends pertaining to this technology in an effort to provide a comprehensive overview of the future development of cell membrane coating technology.

Development of CO2 Selective Poly（Ethylene Oxide）-Based Membranes： From Laboratory to Pilot Plant Scale

Membrane gas separation is one of the most promising technologies for the separation of carbon dioxide （CO2） from various gas streams. One application of this technology is the treatment of flue gases from combustion processes for the purpose of carbon capture and storage. For this application, poly（ethylene oxide）-containing block copolymers such as Pebax or PolyActiveTM polymer are well suited. The thin-film composite membrane that is considered in this overview employs PolyActiveTM polymer as a selective layer material. The membrane shows excellent CO2 permeances of up to 4 m^3（STP）.（m^2·h·bar）^-1 （1 bar = 105 Pa） at a carbon dioxide/nitrogen （CO2/N2） selectivity exceeding 55 at ambient temperature. The membrane can be manufactured reproducibly on a pilot scale and mounted into fiat-sheet membrane modules of different designs. The operating performance of these modules can be accurately predicted by specifically developed simulation tools, which employ single-gas permeation data as the only experimental input. The performance of membranes and modules was investigated in different pilot plant studies, in which flue gas and biogas were used as the feed gas streams. The investigated processes showed a stable separation performance, indicating the applicability of PolyActiveTM polymer as a membrane material for industrialscale gas processing.

Separation performance of horizontal and vertical polyethersulfone hollow fiber UF modules

The effect of hollow fiber module positions （ horizontal and vertical） on separation performance for PVA solution by using polyethersulfone （PES） hollow fiber ultrafiltration （UF） membrane with the molecular weight cut-off （MWCO） 30 000 has been discussed. Experimental results illustrated that the suitable operation conditions for PVA solution were as follows： trans-membrane pressure 2.1 bar, solution temperature 75℃ and feed velocity 0.32 m/s. Under these suitable operation conditions, the permeate flux is from 36.8 L/（m^2 ·h·bar） to 42.9 L/（m^2 ·h·bar） for the horizontal module and from 39.8 L/（m^2 ·h·bar） to 66.6 L/（m^2 ·h·bar） for the vertical module. Besides, the Separation performance of PES hollow fiber UF membrane was better by using vertical hollow fiber module than by using horizontal hollow fiber module. When the trans-membrane pressure increased from 1 bar to 2.1 bar, solution temperature from 50 ℃ to 75 ℃, feed solution velocity from 0.16 m/s to 0.32 m/s, the PVA rejection would increase from 95.8% to 99.7%, 95.4 96 to 98.6 %, 95.8 96 to 99.2 96 for horizontal module respectively, and from 98.8 96 to 99.8 %, 98.6 96 to 99.4 96, 98.5 96 to 99.4 96 for vertical module respectively. Therefore, PVA rejection in PES hollow fiber UF process was more than 98.5 96 for vertical module, and it is suitable for PVA recovery from wastewater.

MATHEMATICAL AND EXPERIMENTAL ANALYSIS OF AIR SEPARATION BY HOLLOW FIBER MEMBRANES

Approximate solutions for gas separation by hollow fiber membranes have been developedby several investigators.However,there are few reports of experimental verification of the models forhigh stage cut separations.In this work,an approximate mathematical model was developed and wasexperimentally verified for high stage cut air separation.Both countercurrent and cocurrent now pat-terns were used.In addition,the applicability of feed-inside mode for low stage cut air separation byhollow fiber membrane was examined.It was found that feed-inside mods was more advantageousthan feed-outside mode when used for the generation of oxygen-enriched air.

Parameters optimization for direct contact membrane distillation based on orthogonal experiment

Parameter optimization integrating operation parameters and structure parameters for the purpose of high permeate flux,high productivity and low exergy consumption of direct contact membrane distillation (DCMD) process was conducted based on Taguchi experimental design. L16(45) orthogonal experiments were carried out with feed inlet temperature,permeate stream inlet temperature,flow rate,module packing density and length-diameter ratio as optimization parameters and with permeate flux,water productivity per unit volume of module and water production per unit exergy loss separately as optimization objectives. By using range analysis method,the dominance degree of the various influencing factors for the three objectives was analyzed and the optimum condition was obtained for the three objectives separately. Furthermore,the multi-objectives optimization was performed based on a weight grade method. The combined optimum conditions are feed inlet temperature 75℃,packing density 30% ,length-diameter ratio 10,permeate stream inlet temperature 30 ℃ and flow rate 25 L/h,which is in order of their dominance degree,and the validity of the optimization scheme was confirmed.

Introducing 3D-potting:a novel production process for artificial membrane lungs with superior blood flow design

Currently,artificial-membrane lungs consist of thousands of hollow fiber membranes where blood flows around the fibers and gas flows inside the fibers,achieving diffusive gas exchange.At both ends of the fibers,the interspaces between the hollow fiber membranes and the plastic housing are filled with glue to separate the gas from the blood phase.During a uniaxial centrifugation process,the glue forms the“potting.”The shape of the cured potting is then determined by the centrifugation process,limiting design possibilities and leading to unfavorable stagnation zones associated with blood clotting.In this study,a new multiaxial centrifugation process was developed,expanding the possible shapes of the potting and allowing for completely new module designs with potentially superior blood flow guidance within the potting margins.Two-phase simulations of the process in conceptual artificial lungs were performed to explore the possibilities of a biaxial centrifugation process and determine suitable parameter sets.A corresponding biaxial centrifugation setup was built to prove feasibility and experimentally validate four conceptual designs,resulting in good agreement with the simulations.In summary,this study shows the feasibility of a multiaxial centrifugation process allowing greater variety in potting shapes,eliminating inefficient stagnation zones and more favorable blood flow conditions in artificial lungs.

基于中空纤维的灌流培养细胞截留技术的研究

近年来由于生物制药行业对于蛋白产品需求的日益增加,连续型细胞培养工艺的灌流培养模式越来越受到重视.为了维持生物反应器中较高的细胞数量和生产力,收获纯度较高的蛋白产品,需要一种良好的分离装置来保留生物反应器中的细胞.本文在比较不同类型的细胞截留技术的基础上,总结了中空纤维过滤技术操作条件温和、通量大、过滤精度高且应用广泛的优势.为了缓解中空纤维过滤过程中存在的膜污染问题,延长膜组件寿命,本文还分析了灌流培养常用的中空纤维膜材质、孔径大小、组件内径、长度及填充密度等设计因素,讨论了不同的切向流过滤操作参数对膜组件的影响,以期为灌流培养工艺领域中细胞分离用中空纤维膜组件的设计与优化提供理论依据.

滑液囊支原体GA组件蛋白的原核表达及间接ELISA方法的建立

【目的】体外表达滑液囊支原体(Mycoplasma synoviae,MS)的GA组件蛋白(GA module-containing protein),建立一种MS抗体检测方法,用于血清学检测及MS抗体水平监测。【方法】分析、筛选MS的GA组件蛋白长链保守结构域,合成重组质粒pET30a-ΔGA-L,转化大肠杆菌BL21(DE3)感受态细胞进行诱导表达,并优化表达条件;通过SDS-PAGE检测重组蛋白的表达,纯化重组蛋白ΔGA-L并进行Western blotting鉴定;以纯化后的重组蛋白ΔGA-L作为包被抗原,建立MS抗体的间接ELISA检测方法,优化反应条件,确定临界值,对其特异性、敏感性、重复性进行检验,并进行临床样品检测。【结果】重组蛋白ΔGA-L的分子质量大小为45.7 ku,最佳表达条件为25℃、0.2 mmol/L IPTG诱导表达5 h,以包涵体形式表达。Western blotting结果表明,重组蛋白ΔGA-L能与MS抗体发生特异性反应。以ΔGA-L抗原包被浓度为0.5μg/mL,一抗稀释度为1∶400,二抗稀释度为1∶12 000为最佳条件,建立了MS抗体间接ELISA检测方法,其阴阳性临界值为0.283;所建立方法特异性强、灵敏度高,有较高稳定性;与商品化MS抗体检测试剂盒总符合率为96%。【结论】本研究成功表达了MS重组蛋白ΔGA-L,所建立的MS抗体间接ELISA检测方法具有良好的特异性、敏感性、重复性,为MS抗体检测提供了有效快捷的方法。

气隙式膜蒸馏技术研究现状和应用

在低碳经济的发展背景下,膜蒸馏技术作为一种兼具优异分离性能和节能潜力的新型分离技术而备受重视。气隙式膜蒸馏作为一种高热效率的膜蒸馏形式,其节能优势更为显著。本文总结了国内外与气隙式膜蒸馏技术相关的研究进展,从传质传热模型、数值模拟和膜组件结构几个方面指出了膜蒸馏技术的主要研究方向。重点介绍了膜蒸馏过程优化的研究和技术应用现状。膜蒸馏过程优化包括通过膜组件结构设计优化、使用改性膜、外加物理场等方式以提高膜通量或减小膜污染。在应用方面,气隙式膜蒸馏技术主要应用于海水淡化、高浓度工业废水处理和浓缩加工等领域。

不同载体对DMBR处理模拟生活污水的影响研究

为探究不同载体对DMBR处理模拟生活污水的影响,以150目尼龙网、200目尼龙网、活性炭海绵作为动态膜载体,测定了DMBR运行过程中DOC、NH3-N、PO43-等污染物质的变化情况;通过出水浊度和TMP等参数判断动态膜层形成时间;提取了动态膜层中EPS并进行定量分析。结果表明,使用尼龙网和活性炭海绵作载体均可以提高出水效果,DOC和NH3-N平均去除率均大于97%,PO43-去除率大于90%,出水平均浊度降低至1.87 NTU以下;浊度等数据表明尼龙网作载体时动态膜可以在24 h内形成,活性炭海绵作载体时动态膜形成时间小于90 min,表现出更好的截留效果;EPS测定结果表明PS为形成膜污染的主要物质。

自清洗聚乙烯亚胺改性纳米平板陶瓷膜MBR在老龄垃圾渗滤液处理中应用实例

针对老龄垃圾渗滤液可生化性低,成分复杂,重金属含量高等特点,采用气浮+厌氧+缺氧+一体式浸没MBR+纳滤+反渗透组合处理工艺。厌氧反应器采用搪瓷材质的UASB。MBR膜采用新型亲水性更强的聚乙烯亚胺改性纳米平板陶瓷膜,同时配套自清洗膜组件,膜组件安装有能对膜片表面进行清洗的毛刷,进一步减轻膜污染,从而提高膜通量。工程调试运行8个月,产水水质标准高于≤生活垃圾卫生填埋场污染控制标准≥(GB16889-2008)表3中的标准,即COD≤60 mg/L,BOD5≤20 mg/L,ρ(氨氮)≤8 mg/L,ρ(总氮)≤20 mg/L,ρ(SS)≤2.0 mg/L等。水处理运行费用为24.0元/m^(3)。

背光模组膜材折边的关键工艺

随着液晶显示技术(LCD)的快速发展,背光模组的组装精度是提升显示效果和产品可靠性的关键因素。针对背光模组组装中膜材折边的技术难点进行了深入研究,提出了一种创新的三次折边技术,以解决膜材折边过程中的角度控制和回弹量管理问题。通过对材料折边回弹量与折边压力、折压时间、过折角度等因素的关系进行力学仿真计算和试验验证,开发了一种膜材仿形折边机构,实现了折边过程的精确控制。该技术通过预折、初压和复压三个阶段,有效控制了折边角度偏差,可保持在±1.5°,显著提高了背光模组的组装精度。试验结果表明,该技术不仅提升了生产效率,降低了物料损耗和返修率,还确保了背光模组的光学性能,为液晶显示器的高性能和可靠性提供了坚实的基础。

基于参数自调节的电氢耦合系统调频控制策略研究

针对含质子交换膜燃料电池(proton exchange membrane fuel cell,PEMFC)的氢储能系统频率控制问题,为提高氢储能系统的频率稳定性,提出了一种基于虚拟参数自调节的系统频率控制策略。其中,电氢耦合系统以PEMFC为依托,光伏、储能电池为辅助,通过PEMFC、光伏、储能电池三者混合向系统综合负荷供电。通过数学模型构建,观察出系统内发生微小扰动后,PEMFC及储能电池的动态响应变化,改变虚拟控制参数,调整系统内的功率分配。由于PEMFC和储能电池动态响应时间不同,对于PEMFC和储能电池采取不同的控制策略,具体体现为对PEMFC采取下垂控制,而对储能电池采取惯量控制,来达到维持系统内频率在正常范围内微小波动并趋于稳定的目的。最后,通过MATLAB/Simulink仿真平台搭建模型验证了所提策略的有效性和优越性。

DMTO碱洗废水的碱回收技术

提出一种以特种膜组件为核心的碱回收技术,用以回收DMTO碱洗废水中的Na_(2)CO_(3)和NaOH。以内蒙古某甲醇制烯烃企业为例,通过中试装置探究并验证了碱回收效果。研究结果表明,气浮与陶瓷膜的预处理组合工艺对水中油状物去除率达到99.8%,有效保障碱回收膜组件的稳定运行。通过两级碱回收技术,每吨废水可回收获得19.12 kg的Na_(2)CO_(3)和1.77 kg的NaOH,碱回收率达到73.4%。本技术可实现废碱的循环利用,为企业节省大量药剂费用,创造良好的经济效益。

Mathematical model analysis on the enhancement of aeration efficiency using ladder-type flat membrane module forms in the Submerged Membrane Bio-reactor(SMBR)

The cross-flow shearing action produced from the inferior aeration in the Submerged Membrane Bio-reactor(SMBR) is an effective way to further improve anti-fouling effects of membrane modules.Based on the widely-applied vertical structure of flat membrane modules,improvements are made that ladder-type flat membrane structure is designed with a certain inclined angle θ so that the cross-flow velocity of bubble near the membrane surface can be held,and the intensity and times of elastic colli-sion between bubbles and membrane surface can be increased.This can improve scouring action of membrane surface on aeration and reduce energy consumption of strong aeration in SMBR.By de-ducing and improving the mathematics model of collision between bubble and vertical flat put forward by Vries,the relatively suitable incline angle θ under certain aeration place and in certain size rang of bubble can be obtained with the computer iterative calculation technology.Finally,for many groups of ladder-type flat membrane in parallel placement in the practical application of SMBR,some sugges-tions are offered:the interval distance of membrane modules is 8―15 mm,and aeration should be op-erated at 5―7 mm among membrane modules,and the optimal design angle of trapeziform membrane is 1.7°―2.5°.