液-液喷射混合装置微观混合特性的研究进展

液-液喷射混合装置具有优异的微观混合特性,特别适用于液-液快反应体系。在研究不同液-液喷射混合装置的微观混合特性时,选取合适的研究方法和定量指标非常关键。本文对比分析了液-液喷射混合装置中常用的微观混合特性研究方法（化学探针法、激光诱导荧光技术和计算流体力学方法）,包括其优缺点、适用范围、选用原则和应用要点,并总结了表征微观混合特性的定量指标。其次,对液-液喷射混合装置进行了系统性的分类,分别介绍了不同液-液喷射混合装置中微观混合特性的影响因素和研究进展,后者主要包括3种研究方法在研究微观混合机理、微观混合特性时间、微观混合过程强化和装置结构优化等方面的进展。最后总结了罐中喷射混合装置和管状喷射混合装置微观混合特性研究存在的不足和后续研究方向。     

稀释合成气微混合燃料喷射燃烧火焰特性研究

研究了耦合CO2稀释和微混合燃料喷射燃烧的火焰特性.结果表明:耦合CO2稀释和微混合燃料喷射燃烧是一种降低合成气扩散火焰NOx生成量的有效途径;实验范围内排放的NOx质量浓度一般低于2mg/m3,排放的CO质量浓度低于10mg/m3,排放的CO质量浓度随火焰热功率的增大而降低;燃烧器出口温度、壁面温度和喷嘴出口温度等均随火焰热功率的增大而升高.     

团聚模型在连续体系中的应用

The micro-mixing time in a continuous system is studied with the incorporation model, in which the direct and indirect solutions are compared and the assumptions and parameters are modified to suit for the continuous system. Results showed that the direct solution is more close to the real mixing state, which is strongly affected by the change of the concentrations in the surroundings caused by the ratio of the continuous flows. While, the real concentrations in the aggregate have significant effect on both the solutions, even more than ten times, especially c_H⁺ in the aggregate. By fitting, the relationships of X_s and t_m resulted from both solutions are similar,lgX_s is linear to lgt_m when t_m <0.01 s, and is quadratic when t_m is larger.     

旋转填充床内微观混合化学反应计算数学模型

在层状扩散模型的基础上, 以1-萘酚与对氨基苯磺酸重氮盐在旋转填充床内发生的竞争串联偶氮化合反应为例，探讨了填充床内的微观混合情况.引进了两个调整反应物与生成物关系的参数，对整个反应过程建立了一个计算数学模型;并进行了计算，计算预测的结果与实验数据在规律上和数值上都较好符合.     

搅拌槽内微观混合研究的回顾与展望(英文)

Mixing problems are most likely encountered and sometimes can be severe in scaling-up projects.Micro-mixing is an important aspect for fast or quasi-instantaneous reactions.Poor micro-mixing might produce more undesired by-products,leading to higher purification costs.This paper gives an extensive review and analysis of micro-mixing studies in single-and multiphase stirred tanks.The relevant experiment techniques,micro-mixing models and numerical approaches are critically reviewed and analyzed with remarks and perspectives.The reported studies on two-phase micro-mixing experiments and on the impact of the presence of the dispersed phases on turbu-lence have been limited to a narrow range of conditions.More importantly,disparities widely exist among different reports.Both Lagrangian and Eulerian models are based on oversimplified assumptions,which may lead to uncer-tainties or even unrealistic results.A heuristic model,which is from the perspective of CFD(computational fluid dynamics) and can cover the whole spectrum of scales and also focus on every sub-process,is desired in the future.     

Interaction between micro- and macro-mixing during reactions in agitated tanks

The present investigation focusses on the interactions between micro-and macro-mixing in a stirred tank reactor, operated in the semi-batch mode. With long feed times only micromixing controls reaction, but below a critical feed time macroscopic gradients also become important. Experiments generated a coherent data set which can be used as a design guide and also for model validation. A competitive, consecutive azocoupling reaction was carried out, whereby imperfect mixing produces finite values of X_S (yield of secondary product) which can be conveniently used as a mixing index. The influences of feed location, feed rate, stirrer speed, concentrations and vessel size on selectivity were studied. The micromixing model of Baldyga and Bourne (1989) was extended to include interactions between macro-and micro-mixing and should be valid for feed times below the critical value, although not so short as the macromixing time in the vessel. Model predictions were compared with the experimental results.     

叠氮化银起爆药连续化合成芯片的设计与应用研究

针对叠氮化银（AgN_3,简写为SA）起爆药合成过程对于反应溶液快速混合的要求,设计制作了连续反向旋T形微混合芯片,并采用Ansys Fluent仿真模拟软件对芯片结构及反应物流速等因素对混合效率的影响规律进行了研究,优化获得了高效微混合芯片结构。使用该芯片进行了纳米SA起爆药的连续化合成,通过扫描电子显微镜（SEM）、X射线衍射（XRD）、傅里叶变换红外光谱（FTIR）、差示扫描量热（DSC）研究了SA起爆药的形貌、成分结构与热性能。结果表明：当微混合芯片的通道尺寸为1 mm,对撞角度180°,反应物流速4 mL·min^-1以上时,可获得接近100%的混合效率。通过调节反应物流速、浓度和添加表面活性剂,可有效调控产物粒径及其分布,且反应产物主要成分为正交晶系的AgN₃晶体。相较常规方法,使用微流控方法制备的SA起爆药放热峰温度由365.2 ℃提前到358.2 ℃（降低7 ℃）,且放热量由851.6 kJ·kg^-1升高到976.7 kJ·kg^-1（升高14.7%）,表明微流控方法制备的SA起爆药具有更高的反应活性和能量。     

喷射反应器内液-液湍流微观混合的研究

通过定义局部分离度,来定量表征喷射器内液-液湍流微观混合规律。其定义式为:(实验所得H~+浓度-模拟所得H~+浓度)/模拟所得H~+浓度。选用酸碱反应体系,利用PLIF技术得到沿喷射器轴线的H~+浓度;采用Fluent软件,利用Standard k-ε模型,模拟获得相同操作条件下的H~+浓度变化趋势。得到不同操作条件下,分离度沿喷射器轴线的变化,结果表明:(1)引流速度不变,喷嘴速度越大,两流体越容易达到微观尺度的均匀混合;(2)喷嘴速度不变,引流速度越大,两流体反而不容易达到微观尺度上的均匀混合;(3)速度比一定的情况下,喷嘴速度越大,越有利于流体的微观混合。     

Functional properties of two low-molecular-weight glutenin subunits carrying additional cysteine residues from hybrid introgression line II-12 derived from Triticum aestivum and Agropyron elongatum

The functional properties of the various alleles of the low-molecular-weight glutenin subunits (LMW-GS) have not been widely addressed, even though they are important in the context of wheat end-use quality improvement. Two LMW-GS alleles introgressed into bread wheat from tall wheatgrass via asymmetric somatic hybridization differ from the norm by encoding either two or three additional cysteine residues. These genes were isolated and expressed heterologously in Escherichia coli to obtain sufficient product amounts for incorporation into the flour of a poor quality cultivar for the purpose of a micro-mixing test. Their effect was to decrease both the time to peak dough resistance and the peak width, while having no effect on either the 8 min curve width or the right of peak slope. Several effects on wheat dough properties were discussed in this paper.     

Mixing Characteristics and Bubble Behavior in an Airlift Internal Loop Reactor with Low Aspect Ratio

The present study summarizes the results of macro-and micro-mixing characteristics in an airlift inter-nal loop reactor with low aspect ratio （H/D≤5） using the electrolytic tracer response technique and the method of parallel competing reactions respectively. The micro-mixing has never been investigated in airlift loop reactors. The dual-tip electrical conductivity probe technique is used for measurement of local bubble behavior in the reactor. The effects of several operating parameters and geometric variables are investigated. It is found that the increase in su-perficial gas velocity corresponds to the increase in energy input, liquid circulation velocity and shear rate, decreas-ing the macro-mixing time and segregation index. Moreover, it is shown that top clearance and draft diameter affect flow resistance. However, the bubble redistribution with a screen mesh on the perforated plate distributor for macro-mixing is insignificant. The top region with a high energy dissipation rate is a suitable location for feeding reactants. The analysis of present experimental data provides a valuable insight into the interaction between gas and liquid phases for mixing and improves the understanding of intrinsic roles of hydrodynamics upon the reactor de-sign and operating parameter selection.