垂直管内高粘假塑性流体流沸腾传热

用高粘流体了垂直管内流动沸腾传热实验研究，建立了流动沸腾传热给热系数关联式。     

双行星动力混合机搅拌桨受力分析

通过对双行星动力混合机搅拌桨的力学分析,并对搅拌过程中所受应力应变和变形规律进行研究分析,得出在搅拌过程中,越靠近搅拌桶底部,桨叶所受的压力越大,变形也越大;而最大应力与最大应变出现在搅拌方轴和换接器相连处。为以后的研究提供了理论参考依据。     

高粘变物性流体垂直管内流动传热

对高粘变物性流体管内传热进行了计算机仿真计算.结果表明,高粘流体传热时径向温差很大,采用较小的加热管径可以有效地减小径向温差.     

高粘流体换热器的设计特点

用计算机仿真研究了高粘流体流动传热,分析了高粘假塑性变物性流体流动特点和压力降,设计高粘流体换热器时,应考虑变物性及加热管壁温对压力降的影响;分析了高粘流体换热器的管程径向温差及影响因素.     

高粘假塑性流体流动沸腾传热研究

用高粘假塑性流体进行了垂直管内流动沸腾传热实验研究，建立了流动沸腾传热给热系数关联式。     

高粘流体换热器加热管的径向温差

该文将用计算机对高粘流体流动传热进行计算机仿真,研究高粘流体换热器的设计特点.文章以用SIMPLER方法,以聚苯乙烯一苯乙烯高粘聚合流体为例,对高粘流体管内传热进行仿真计算.经计算机仿真表明,高粘流体换热器加热管的径向温差远较低粘流体大,这在换热器设计中应予充分注意.     

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％。     

高粘流体传热的仿真计算及换热器设计

用计算机仿真分析了高粘流体流动传热的径向温差,并指出了在高粘流体换热器设计时,应采用较小管径以减小径向温差。     

高粘变物性流体换热器管程压力降及流动的计算机仿真研究

高粘假塑性变物性流体换热器的管程压力降受壁温影响较大，对此本文用计算机仿真进行研究。     

组合桨搅拌槽内高黏流体混合特性的数值模拟

利用计算流体力学数值模拟方法,对直段桨为双螺带式和Paravisc式以及底桨为锚式和变径双螺带式的组合桨功率和混合时间进行了研究,并对其中最优桨型进行了放大规律的探索。通过数值模拟得到了4种组合桨中各单桨及组合桨的功率准数关联式,提出组合桨中各桨之间功率上的反作用关系。在10种组合桨中,Paravisc-锚式组合桨达到完全混合时所转圈数最少,且在相同转速下量纲一剪切量较大,混合特性最优,将其从体积为100 L的搅拌槽内放大至200 L和500 L搅拌槽中,发现其符合桨端线速度的放大准则。文中对各桨型的功率特性、混合特性和放大规律的分析,可为工业设计和优化高黏度流体组合桨参数提供重要参考。     

Experimental study of reactive mixing in a mini-scale mixer by laser-induced fluorescence technique

The liquid–liquid mixing process coupled with chemical reactions in a mini-scale jet mixer was visualized by reactive laser-induced fluorescence (reactive-LIF) technique for a deep understanding of the interplay between the mixing and the simultaneous reactions. A novel approach for implementing the reactive-LIF measurements was advanced in this work, where the principle was based on the quenching of the fluorescence signal emitted from the Rhodamine-B dye using the mechanism of Fenton reaction. The purely physical mixing and the reactive mixing processes were investigated extensively by comparing the concentration fields under different operating conditions, i.e. the different momentum ratios between the jet and the bulk flows, and the different Reynolds numbers in the mixing channel of a mini-scale mixer. The results revealed that the transient dynamics in the reactive mixing process cannot be precisely understood based on the time-averaged concentration fields from either the physical or the reactive mixing measurements. The coupled mixing and the reaction processes occurred simultaneously, unless the rapid mixing was achieved by tuning the operating conditions so that the processes can be decoupled into two isolated ones.     

拉伸流动静态混合器混合性能的实验研究

设计了1种能够增强聚合物混合效果的拉伸流动静态混合器（EFM）,以高密度聚乙烯/聚苯乙烯（PE⁃HD/PS）作为混合体系,根据共混体系扫描电子显微镜（SEM）照片及分散相的平均粒径,研究了不同盘形结构和不同盘棱间隙（δ）（0.125~2.0 mm）下EFM的混合性能。结果表明,EFM的盘形入口结构对其混合性能影响较小,混合能力随盘棱顶端圆角半径的增大而有所提升,随δ的增大出现先降低再升高又降低的变化趋势。     

Experimental evaluation of gas mixing with a static microstructure mixer

Mixing plays an important role in chemical reaction engineering. In the last years several types of static microstructure mixers have been developed. The characterization of microstructure mixing is difficult to perform as the dimensions are too small for conventional methods. Therefore, we report a method to characterize the mixing of two gases directly by measuring the concentration of the gases at the outlet of the mixer. The experiments have been carried out up to gas flows of 5000 ml/min STP per passage. The mixing degree and mixing length were determined as well as the mixing time was calculated. These values depend on the properties of the gases and other parameters as temperature and gas velocity. Thus complete mixing is achieved after a mixing length, i.e., the distance to the microchannel outlet, of only 300-800 μm. Corresponding mixing times are just 100-600 μs. Furthermore, discontinuities in the mixing characteristic can be explained with the results obtained. Also design parameters for a further improvement of the mixer geometry individually for various applications could be set up.     

Experimental study of the mixing kinetics of binary pharmaceutical powder mixtures in a laboratory hoop mixer

As increasingly commented by the literature during the last 5 years, estimating the homogeneity of a powder mixture and following powder mixing processes is not a simple task. In this paper, we present the development and statistical validation of a sampling methodology for defining the number of samples required to provide a reasonable estimation of the homogeneity attained in a laboratory scale tumbler mixer. This method is then used to follow the mixing kinetics of a dilute binary powder mixture in a hoop mixer. Special attention is paid to the statistical meaning of the values obtained and the influence of the physical characteristics such as particle size and shape. The role of the particle shape of the majority powder is particularly emphasised and it is quantitatively demonstrated that spherical particles are harder to mix and more ready to segregate than particles with irregular shapes. The different mixing mechanisms at play are identified; the practical limits of use of such tumbler mixers with pharmaceutical powders are discussed.     

Axial mixing in a ploughshare mixer

Motion is studied within a bladed 5 l ploughshare mixer for granular solids at two rotor frequencies, 2 Hz and 4 Hz, for fill levels between 12.5% and 70%. Positron emission particle tracking is used to follow the motion of a single radioactive tracer. Particles circulate around the bed in the transaxial plane in the direction of blade rotation. Axial motion perpendicular to this plane is significantly less and is largely contained in the region between the planes of rotation of adjacent blades. Axial mixing between these inter-plough regions is determined by calculating the transport rate across these planes. Transport is greater at 4 Hz than at 2 Hz, but decreases as fill level increases. Axial transport is further studied by recording the location of the tracer as it crosses each plane of blade rotation. These passages can be described as occurring either; (i), in defined regions of the bed; or (ii), by leading or lagging the blades by a constant angle. A transition from (i) to (ii) occurs as fill level increases. At 4 Hz or with oily rice, the transition occurs at lower fill levels.     

Computational study of convective–diffusive mixing in a microchannel mixer

Scalar mixing due to convection and diffusion in a microchannel mixer is studied using CFD. A method is developed to quantitatively measure the effect of false diffusion on scalar decay rate. This method computes an average false diffusivity from a given numerical solution and it is not limited to any particular numerical scheme. It is found that a range of molecular diffusivity exist in which average false diffusion is smaller than molecular diffusion and scalar decay rates can be computed accurately with CFD in the mixer. This range of molecular diffusivity covers most of the liquid solutions encountered in chemical and biochemical engineering. When effective diffusivity is used, this range can be further expanded. The predicted mixing structures agree well with experimental results in literature. The classical lamellar structures of the baker's transformation are strongly affected by diffusion. The striation doubling process is destroyed by diffusion broadening at very early stage in the mixer. The optimal mixing is achieved at low Re when the mixing mechanism in the mixer is the baker's transformation. At higher Re, secondary flow is generated and the mixing mechanism is the competition of the kinematics of the baker's transformation and the dynamics of the cross sectional flow. Results show that the secondary flow hinders mixing and the scalar decays at lower exponential rates than when the mixing is due to the baker's transformation alone.     

Powder mixing in a horizontal batch mixer

The mixing process in a horizontal batch mixer with a twin spiral rotor has been investigated.A mixture of crushed wheat and sodium chloride was mixed in a model mixer. The concentration of sodium chloride in mixture samples was checked as a function of the mixing time and sampling place for various degrees of mixer filling. The sample composition was determined by conductometric determination of sodium chloride in water extracts of the sample. From the values obtained, the mixing degree was calculated as defined by the variation coefficient along the whole mixer, as a function of the mixing time.In analysing the data and empirical correlation between the concentration of component under study and the place and time of mixing, C/C? = f(x, t) was obtained and compared with industrial experiments using radionuclides as tracers.     

0.3L密炼机混炼工艺的实验研究

为了研究0.3L密炼机的混炼工艺参数对混炼胶性能的影响,本文采用半钢子午胎配方0°转子相位和90°转子相位下分别设置不同的工艺参数进行混炼.由混炼胶的流动性能和硫化胶的机械性能确定最佳工艺参数为:填充系数0.65、混炼时长300 s、转子转速80 r/min.     

Electromagnetically induced chaotic mixing in a pipe mixer

A numerical investigation is carried out to study the mixing by chaotic advection in an electromagnetically driven pipe mixer. It consists of a pipe with two inner electrodes which are energized alternatively. An externally applied magnetic field along the flow direction interacts with the local electric currents inducing a spatially varying electromagnetic body force in the model fluid. The system is an extension of Aref's blinking vortex model to three dimensions. The Lagrangian motion of passive tracer particles is numerically simulated to quantify the degree of stirring. The model predictions indicate that the chaotic mixing is strongly dependent on the modified Hartmann number, the electrode switching frequency and the electrode separation distance. A comparison with numerical simulation results obtained using a dimensional model with glass melt shows that the chaotic mixing behavior of the glass melt is very close to the non-dimensional model predictions. The computational results presented here will be useful for developing efficient glass melt homogenisation systems.     

高黏度流体混合研究进展

综述了近20年来高黏度流体混合领域的研究进展,阐述了文献中常用实验物系的选择、流变特性的描述及混合性能的研究评价方法等;介绍了高黏度物系搅拌混合设备的主要类型:立式、卧式及单轴、双轴等,以及各种形式搅拌混合设备的研究成果。指出今后仍需进行深入研究的领域:同轴异速、双轴异速、立式搅拌设备及卧式搅拌装置中的桨型优化及混合性能评价;CFD在高黏度混合领域的研究仍有待深入。