微通道内乙醇胺吸收CO2的过程特征（英文）

Process characteristics of CO2 absorption using aqueous monoethanolamine(MEA) in a microchannel reactor were investigated experimentally in this work.A T-type rectangular microchannel with a hydraulic diameter of 408 μm was used.Operating parameters,i.e.temperature,pressure and molar ratio of MEA to CO2 were studied.Under 3 MPa pressure,the mole fraction of CO2 in gas phase could decrease from 32.3% to 300×10?6 at least when gas hourly space velocity ranged from 14400 to 68600 h?1 and molar ratio of MEA to CO2 was kept at 2.2.In particular,the effects of temperature on CO2 absorption flux,mass transfer driving force,gas-liquid contact time and en-hancement factor were analyzed in detail and found that mass transfer enhancement by chemical reaction was a crucial factor for the process of CO2 absorption.     

快速检测病原菌含量的简易微流控系统

针对现有水产养殖病原菌检测时效性差、自动化程度低的缺点,提出了一种快速检测水产养殖病原菌含量的简易微流控系统研究方法。该系统将微电极构造于微流控芯片通道底部并与数字阻抗测量电路连接,通过在磁珠表面包被水产病原菌抗体,利用外部高斯磁场控制诱导磁珠捕获水产病原菌,并将水产病原菌与磁珠结合体带至微电极阵列,通过在电极端构建基于阻抗测量的计数电路,从而有效检测水产病原菌含量。研究结果表明该系统能够有效测量水产病原菌的含量,检测时间由传统的平板计数法48 h减少至30 min,检测效率提高为原来的60多倍,检出限相比现有的微流控阻抗法缩小100倍。     

Static mixers for laminar flow reactors with low aspect ratios

Conventional static mixers typically require high length to diameter ratios to be effective. This paper considers static mixers design to increase first appearance times in short, fat reactors. Three types are considered: conical baffles and annular baffles for tubular reactors and axial baffles for reactors with a rectangular cross-section. Relatively simple designs allow production increases (or reactor volume decreases) on the order of 20–50%.     

Performance of Kenics static mixer over a wide range of Reynolds number

The present study deals with the numerical simulation of flow patterns and mixing behaviour in Kenics static mixer over a wide range of Reynolds number. Three different sets of Kenics mixer (aspect ratio = 1.5) comprised of 3, 9 and 25 elements each have been characterized. The Reynolds number was varied in the range of 1 to 25,000 (i.e., from laminar to turbulent flow regime). The numerical approach takes into account the aspects of the fluid flow at higher Reynolds number values including circumferential velocity profiles at different cross-sections within the Kenics mixer, which were neglected in previous studies. It was observed that cross-sectional mixing in the turbulent flow regime takes place up to 30% of each element length at element-to-element transition; beyond that velocity profiles were uniform. The experiments were also carried out to measure the circumferential and axial velocity profiles and pressure drop in three different Kenics Mixers using air as fluid. The pressure drop per unit element (ΔP/η) was found to be independent of the number of Kenics mixing elements used in the system. The total pressure drop across Kenics mixer obtained by CFD simulations were compared with the experimental pressure drop values and correlations available in the literature. The numerical results were found in good agreement with the experimental as well as the results reported in the literature. A new pressure drop correlation in the Kenics static mixer has been developed.     

Computational modelling of industrial pulp stock chests

Agitated pulp stock chests are the most widely used mixers in pulp and paper manufacture. Stock chests are used for a number of purposes, including attenuation of high‐frequency disturbances in pulp properties (such as mixture composition, fibre mass concentration, and suspension freeness) and are designed using semi‐empirical rules based largely on previous experience. Tests made on both laboratory and industrial‐scale pulp chests indicate that they are subject to non‐ideal flows, including channelling and creation of dead zones. In the present work, a commercial computational fluid dynamic (CFD) software (Fluent) is used to model two industrial pulp stock chests. The first chest is rectangular, agitated using a single side‐entering impeller, and feeds a mixture of chemical pulps at 3.5% mass concentration (C_m) to a papermachine. The second chest has rectangular geometry, with a mid‐feather wall used to direct suspension flow through a U‐shaped trajectory past four side‐entering impellers. This chest is used to remove latency from a C_m = 3.5% thermomechanical pulp suspension ahead of stock screening. For CFD computations, pulp rheology was described using a modified Hershel–Buckley model. Steady‐state simulations were made corresponding to process conditions during mill tests. The calculated steady‐state flows were then used to determine the dynamic response of the virtual chests and then compared with experimental measurements and found to agree reasonably well. The computed flow fields provided insight into mixing processes occurring within the chests, showing cavern formation around the impellers (which reduced the agitated volume available for mixing). Mass‐less particle tracking, using the steady‐state flow field, gave insight into the stagnant regions and bypassing zones created in the vessels. This paper discusses difficulties encountered in characterising the mixing (both experimentally and computationally) and the limitations of the industrial data.     

One-step creation of hierarchical fractal structures

Relatively recently, we advanced a route to create, in a controlled fashion, combined horizontal and vertical stratified structures by simple and energy-efficient processing operations employing static mixing elements. While in state-of-the-art static mixing the focus is on layer multiplication, here the aim is to create hierarchical fractal structures. Therefore, the main question addressed in this article is how structures, rather than layers, can be multiplied. The key aspect is the addition of layers on the sides or in the midplane of the flow during the process; every addition step increases the hierarchy by one level. This article derives the general formalism for forming fractal structures with controlled hierarchy, and we develop the language required to design and construct the dies. The main part of the article addresses this main topic and is based on the splitting serpentine static mixer geometry that can be easily made on the parting surfaces of a mold on both the micro- and the macroscale. The second part of the article addresses the strategy to minimize the number of mirroring steps, eventually avoiding mirroring completely, and is based on the rotation-free multiflux static mixer geometry. With the design language derived, complex hierarchical fractal structures can be generated simply by changing the number and sequence of operators within extrusion dies or molds, providing a one-step solution to produce material structures for potential use in diverse applications ranging from advanced mechanical systems to photovoltaic devices, where controlled assembly of dissimilar materials, and the realization of huge interfaces and genuine cocontinuity throughout the cross section, is critical.     

Microfluidic Templated Multicompartment Microgels for 3D Encapsulation and Pairing of Single Cells

Controlled encapsulation and pairing of single cells within a confined 3D matrix can enable the replication of the highly ordered cellular structure of human tissues. Microgels with independently controlled compartments that can encapsulate cells within separately confined hydrogel matrices would provide precise control over the route of pairing single cells. Here, a one‐step microfluidic method is presented to generate monodisperse multicompartment microgels that can be used as a 3D matrix to pair single cells in a highly biocompatible manner. A method is presented to induce microgels formation on chip, followed by direct extraction of the microgels from oil phase, thereby avoiding prolonged exposure of the microgels to the oil. It is further demonstrated that by entrapping stem cells with niche cells within separate but adjacent compartments of the microgels, it can create complex stem cell niche microenvironments in a controlled manner, which can serve as a useful tool for the study of cell–cell interactions. This microfluidic technique represents a significant step toward high‐throughput single cells encapsulation and pairing for the study of intercellular communications at single cell level, which is of significant importance for cell biology, stem cell therapy, and tissue engineering.     

整合纸基微流控检测芯片的食药纸包装

目的探索纸质食品、药品包装与纸基微流控检测芯片的整合方法与规律。方法在传统纸质食品或药品包装的内表面,通过喷蜡打印的方法,整合具有特定生物化学检测作用的纸基微流控芯片,并探索微流体在包装内表面构成的纸基微流控芯片中的运用规律。结果通过喷蜡打印,成功地将纸基微流控芯片整合在了传统纸质食药包装的内表面,经过测试可以完成液体pH检测等基础生物化学检测应用。结论将纸基微流控芯片与食药纸质包装相结合,为食品、药品的实时和现场自我检测提供了新的思路和手段,该方法不仅成本低廉、易于操作,且检测精度高。