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CFD and experimental investigations on the micromixing performance of single countercurrent-flow microchannel reactor

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Chinese Journal of Chemical Engineering 2019年第5期27卷 1079-1088页

作者： Kunpeng Cheng Chunyu Liu Tianyu Guo lixiong wen State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

Microchannel reactors are widely used in different fields due to their intensive micromixing and, thus, high masstransfer efficiency. In this work, a single countercurrent-flow microchannel reactor(S-CFMCR) at the size of ~1 mm was developed by steel micro-capillary and laser drilling technology. Utilizing the Villermaux/Dushman parallel competing reaction, numerical and experimental studies were carried out to investigate the micromixing performance(expressed as the segregation index XS) of liquids inside S-CFMCR at the low flow velocity *** effects of various operating conditions and design parameters of S-CFMCR, e.g., inlet Reynolds number(Re),volumetric flow ratio(R), inlet diameter(d) and outlet length(L), on the quality of micromixing were studied qualitatively. It was found that the micromixing efficiency was enhanced with increasing Re, but weakened with the increase of R. Moreover, d and L also have a significant influence on micromixing. CFD results were in good agreement with experimental data. In addition, the visualization of velocity magnitude, turbulent kinetic energy and concentration distributions of various ions inside S-CFMCR was illustrated as well. Based on the incorporation model, the estimated minimum micromixing time tmof S-CFMCR is ~2 × 10-4s.

关键词： Single countercurrent-flow microchannel reactor Micromixing performance CFD Villermaux/Dushman reaction

Preparation of mesoporous silica microspheres with multi-hollow cores and their application in sustained drug release

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Particuology 2010年第5期8卷 447-452页

作者： Chen Zhang Tian Hou Jianfeng Chen lixiong wen Key Lab for Nanomaterials Ministry of Education Beijing University of Chemical Technology Beijing 100029 China Research Center of the Ministry of Education for High Gravity Engineering & Technology Beijing University of Chemical Technology Beijing 100029 China

Mesoporous silica microspheres with multi-hollow cores （MSMMCs） were prepared by an O1/W/O2 double emulsion technique. When tetraethyl orthosilicate （TEOS） was hydrolyzed in the O1/W/O2 double emulsion with P123 （a triblock copolymer with a formula of HO（CH2CH20）20（CH2CH（CH3）O）70（CH2CH2O）20H） dissolved in the aqueous phase, the internal oil droplets would serve as templates for the empty hollow cores, P123 function as templates for the mesopores in the shell, and the aqueous phase act as space-limiting micro-reactors for the hydrolysis process, thus forming MSMMCs with controllable size and hollow cores. After further modification by a high-temperature aging process, the prepared MSMMCs had a diameter of 2-10 μm, with macromulti-hollow cores with a size of 100-1000 nm, mesopores in the shell with a size of 3.8-4.4 nm, and a surface area of 383-735 m2/g. In addition, MSMMCs were used as carriers to load avermectin through an immersing and evaporating process, and the loaded avermectin showed a well sustained release behavior from the MSMMCs matrix. This study demonstrated a promising and simple method for preparing silica micro-particles with porous multi-hollow core structure for sustained release applications.

关键词： SilicaPreparationHollow structureSustained release

Experimental investigation of nanoparticles precipitation in a rotating packed bed

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Particuology 2010年第4期8卷 372-378页

作者： Yang Xiang Guangwen Chu lixiong wen Kuang Yang Guangting Xiao Jianfeng Chen Key Laboratory for Nanomateriais Ministry of Education and Research Center of the Ministry of Education for High Gravity Engineering and Technology.Beijing University of Chemical Technology. Beijing 100029 China

Precipitation of BaSO4 nanoparticles was studied for the first time in a specially designed rotating packed bed （RPB）, which allowed sampling at different radial positions to provide better insight of the mechanism of precipitation in RPB. Particle size and morphology were characterized by TEM, while the quality of synthesized BaSO4 powders was analyzed by XRD and BET, and compared with those prepared in a stirred-tank reactor. The important role of the inlet region of the RPB in the whole precipitation process was experimentally confirmed, as a significant essence for the design of industrial RPB for the precipitation of sparingly soluble materials. The effects of different operating conditions on particle size were also investigated, showing that particle size decreases with increasing rotational speed and liquid flow rate, due to the enhancement of micromixing in the RPB.

关键词： Rotating packing bed BaSO4 Nanoparticle Precipitation Mixing

Controllable precipitation of naproxen micro-particles with different morphologies

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Particuology 2012年第5期10卷 634-643页

作者： Peng Cheng KangkangJin Jing Cheng Fang Yang Zhigang Shen Jianfeng Chen lixiong wen State Key Laboratory of Organic-lnorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering&Technology Beijing University of Chemical TechnologyBeijing 100029China

A simple precipitation method was proposed to prepare naproxen micro-particles with different controllable morphologies, using capillary video microscopy to study the precipitation process. Different particle shapes were obtained including spherical, platelet-like, stick-like, needle-like, and butterfly-like, all in the micro-size range. It was found that the sizes and morphologies of the formed naproxen particles were sensitive to the nature and concentration of the added surfactant, and depended significantly on processing conditions such as temperature, stirring speed, and initial drug concentration. In addition, pre- cipitation with different surfactant types and concentrations would not affect the crystal microstructure of the formed nanroxen oarticles.

关键词： PrecipitationCrystal growthNaproxenSurfactants

Numerical and experimental investigations of liquid mixing in two-stage micro-impinging stream reactors

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Chinese Journal of Chemical Engineering 2017年第4期25卷 391-400页

作者： Tianyu Guo Bin Ruan Zhiwei Liu Muhammad Ali Jamal lixiong wen Jianfeng Chen State Key Laboratory of Organic-Inorganic Composites Beijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

A two-stage micro-impinging stream reactor(TS-MISR) that combined a first pre-mixing stage with a second micro-impinging stream reacting stage for continuous multi-component reacting systems has been built from commercial T-junctions and steel micro-capillaries. Both of operating parameters and reactor configurations,such as jet Reynolds number(Rej), volumetric flow ratio(R), the first-stage junction angle(φ), the connecting capillary length(Lc) and connecting capillary diameter(dc), had significant effects on the micromixing efficiency of the reactor. Such effects were investigated for both of the two stage structures, respectively, by experimental and CFD methods and were optimized for the best micromixing performance. Intensified micromixing among at least three reacting components can be achieved in a continuous mode by using TS-MISR; therefore, it is expected that the TS-MISR will produce products of higher quality with more uniform and stable element distribution.

关键词： mixing junction volumetric connecting reacting capillary length turbulence viscosity outlet

POROUS SILICA NANO-TUBE AS HOST FOR ENZYME IMMOBILIZATION

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China Particuology 2004年第6期2卷 270-273页

作者： Haomin Ding lixiong wen Jianfeng Chen Key Lab for Nanomaterials Ministry of EducationResearch Center of the Ministry of Education for High Gravity Engineering&TechnologyBeijing University of Chemical TechnologyBeijing 100029P.R.China

With their hollow morphology and large openings, the as-synthesized porous silica nano-tubes (NTPS), prepared through a sol-gel routine by using nano-sized needle-shaped CaCO3 particles as templates, were used as host for enzyme immobilization. Bioimmobilization study showed that enzyme molecules could not only be adsorbed on the external surface of NTPS but also entrapped in their inner hollow cores, leading to higher enzyme loading capacities of NTPS (more than 350 mg/g silica) in a shorter time, as compared to common porous silica (less than 50 mg/g) and most conventional mesoporous silica materials (less than 100 mg/g).

关键词： porous silica nano-tube nanosized CaCO_(3) lysozyme enzyme immobilization

Effects of polyethylenimine on the dispersibility of hollow silica nanoparticles

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Frontiers of Chemical Science and Engineering 2007年第3期1卷 277-282页

作者： wen lixiong WANG Qing ZHENG Tianyuan CHEN Jianfeng Key Lab for Nanomaterials Ministry of EducationBeijing University of Chemical TechnologyBeijing 100029China Research Center of the Ministry of Education for High Gravity Engineering and Technology Beijing University of Chemical TechnologyBeijing 100029China

In this study,two different methods were applied to disperse hollow silica nanoparticles(HSNP);one employed polyethylenimine(PEI)as the dispersant during the synthesis processes for preparing HSNP,while the other added PEI into suspensions of the prepared HSNP and used milling treatment to achieve the desired *** was found that adding PEI during the synthesis process of HSNP had no noticeable improvement in the dispersion,while adding PEI into suspen-sions of the prepared HSNP and utilizing milling treatment resulted in remarkable dispersion ***,the latter was chosen as the method in dispersing HSNP *** adsorption of PEI on the surface of HSNP and the stability of the aqueous suspensions was *** results indicated that the adsorption of PEI on the surface of HSNP would increase the repulsive energy among particles,hence reducing the agglomeration of HSNP and improving the stability of the aqueous *** change of HSNP’s ■ potential after adding PEI and the rela-tionship between the adsorbed amount of PEI and pH were also investigated.

关键词： hollow silica nano-particles(HSNP),disper-sion polyethylenimine(PEI),■potential,adsorption

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蓄盐缓释融雪抑冰材料的制备及性能研究

北京化工大学学报（自然科学版） 2020年第2期47卷 44-50页

作者：赵晔文利雄北京化工大学教育部超重力工程研究中心北京100029

通过表面改性试验、溶出试验和溶液电导率测定试验,筛选出可用于蓄盐缓释融雪抑冰材料的载体(载体A)和表面改性剂(表面改性剂J),通过优化制备方法和成分配比,开发出具有降低溶液冰点功能和缓释功能的蓄盐缓释融雪抑冰材料。吸附试验和... 详细信息

通过表面改性试验、溶出试验和溶液电导率测定试验,筛选出可用于蓄盐缓释融雪抑冰材料的载体(载体A)和表面改性剂(表面改性剂J),通过优化制备方法和成分配比,开发出具有降低溶液冰点功能和缓释功能的蓄盐缓释融雪抑冰材料。吸附试验和电导率测定试验的结果表明:载体A能够吸附的氯化钠含量较高,适合作为材料的载体;采用湿法吸附制备的融雪抑冰材料的缓释性能优于干法吸附制备的材料;随着表面改性剂J添加量的增大,融雪抑冰材料的缓释性增强。自制的蓄盐缓释融雪抑冰材料的组成为氯化钠、载体A、表面改性剂J,三者的质量分数分别为57.91%、38.60%、3.49%。溶出试验和溶液冰点测试试验表明自制的蓄盐缓释融雪抑冰材料具有良好的缓释性和降低溶液冰点能力。

关键词：蓄盐缓释融雪抑冰材料缓释性冰点溶出性试验

对流微通道反应器制备Ni2P材料及Co掺杂改性

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北京化工大学学报（自然科学版） 2020年第3期47卷 1-11页

作者：杨越文利雄北京化工大学教育部超重力工程研究中心北京100029

使用NiCl2·6H2O、KOH、NaH2PO2·2H2O和CoCl2·6H2O等为反应物,在对流微通道反应器(CFMCR)中制备了Ni(OH)2前驱体,然后在PH 3气氛中将其还原,最后经酸洗得到目标产物Ni2P。探讨了CFMCR反应工艺条件(包括体积流量、pH和陈化时间)和磷化... 详细信息

使用NiCl2·6H2O、KOH、NaH2PO2·2H2O和CoCl2·6H2O等为反应物,在对流微通道反应器(CFMCR)中制备了Ni(OH)2前驱体,然后在PH 3气氛中将其还原,最后经酸洗得到目标产物Ni2P。探讨了CFMCR反应工艺条件(包括体积流量、pH和陈化时间)和磷化反应温度等对制备的Ni(OH)2前驱体及最终的Ni2P材料性能的影响,确定了制备Ni2P材料的最佳工艺条件,并利用CFMCR对制备的Ni2P材料进行了Co掺杂改性,提高了材料的充放电循环性能以及比电容。结果表明,利用CFMCR制备的Ni2P材料最高比电容可达到1200F/g,500次恒流充放电循环后比电容保有率约为65%;掺杂Co元素制备的Ni-Co-P复合材料最高比电容为1475F/g,500次恒流充放电循环后比电容保有率约为84%。

关键词：微反应器磷化镍超级电容器材料比电容