扰动元件强化粘稠液体传热的研究

针对粘稠液体传热系数很低这一现象,开发了MC新型强化传热扰动元件。该元件以圆环作为基本扰动部件,在一个横截面上将若干个小圆环以不同方式组合成一个单元,形成圆弧网格型或球网格型.圆环与管子内壁紧密接触,单元节距可以改变构成不同线密度。以1％CMC水溶液作为粘性介质对节距为24、40、60、80、160及400～40 mm变密度六种元件进行实验研究。在Ae<100,Pr数为5～1300m范围内,管内传热膜系数较光管增加4～6倍,摩擦因子为光管的10～20倍。因此可以认为MC型元件是一种低阻高效的传热强化元件。并从流体力学基本原理对强化机理进行了分析。     

Prediction of Power Consumption in a Mechanically Agitated Gassed Reactor in Viscous Batches

Volumetric mass transfer coefficient, power input, and gas holdup are key parameters in the design of mechanically agitated gas‐liquid contactors. Although the majority of industrial batches are of higher viscosity, reliable transport characteristics correlations for viscous batches are lacking in literature. These correlations are often based on the power input as the scale of energy dissipation. In order to develop reliable power input correlations, its measurements were carried out in a pilot‐plant vessel using multiple impellers of various types and diameters. Power input correlation shapes providing the best match with the comprehensive database are also expected to predict most precisely the impeller power in industrial‐scale vessels.     

Control of viscous fingering and mixing in miscible displacements with time-dependent rates

In miscible displacements encountered in enhanced oil recovery processes, the unfavorable viscosity contrast between injected solvent and oil usually leads to viscous fingering (VF), a hydrodynamic instability which may result in a lower sweep efficiency and oil recovery. This phenomenon can be observed in a wide range of flows in subsurface porous media. This study examined a simple cyclic time-dependent displacement rate and its effects on the onset and longer development of VF. It is found that such varying displacement rate can either stabilize or destabilize VF, depending on the cycle period, amplitude, and displacement scenarios. The most important mechanism is that such time-dependent rate can effectively change the competition between convection (destabilizing effect) and dispersion (stabilizing effect). This is different from the widely used constant injection rate where the flow instability is actually determined by the Peclet number and mobility contrast for a given scenario. This study therefore provided a new aspect to control VF, either enhance or reduce, with low additional costs. It is therefore both scientifically and practically important for a wide range of flows in subsurface porous media. © 2017 American Institute of Chemical Engineers AIChE J, 65: 360–371, 2019     

Finite difference analysis for entropy optimized flow of Casson fluid with thermo diffusion and diffusion-thermo effects

Heat transportation is a novel prospective in many thermal processes and presents dynamic applications in industrial and thermal polymer processing optimization. The importance of heat transportation is noted in heat exchangers, production of crude oils, combustion, petroleum reservoirs turbine systems, thermal systems, porous media, modeling of resin transfer nuclear reactions etc. In view of such thermal applications the main objective here is to examine entropy in unsteady magnetohydrodynamic of Casson fluid flow. Radiation in addition to dissipation and ohmic heating are analyzed. Entropy is scrutinized employing thermodynamic second law. Characteristics of Soret and Dufour are also examined. Main objective here is to examine irreversibility. Dimensionless version of differential system is obtained through suitable variables. The obtained partial differential system is solved through numerical scheme (Finite difference method). Physical features of fluid flow, temperature, entropy optimization and concentration have been explained. Variations of parameters on drag force, Nusselt number and solutal transfer rate are graphically discussed. Higher fluid parameter leads to improve in velocity and entropy rate. Larger values of radiation parameter boost up thermal field. Entropy rate and velocity have reverse trend for magnetic field. An intensification for concentration is found through Soret number. Higher approximation of Reynold number enhances skin friction and velocity. Thermal transfer rate is augmented versus radiation and magnetic variables.     

Performance Evaluation of Two High‐Shear Impellers in an Unbaffled Stirred Tank

High‐shear impellers (HSIs) are mixers used in industrial stirred tanks to incorporate powders into liquids and break down particle agglomerates. A detailed numerical study of two commercial ring‐style HSIs of laboratory scale was carried out and their performance was compared with the Rushton turbine (RT). It was found that power and pumping numbers or their ratio cannot be simply connected for properly selecting an impeller in applications where highly localized viscous dissipation is desirable. The ratio of the average viscous dissipation in the impeller swept volume to the mean in the entire volume at two constant values of power input turned out to be lower for HSIs compared to that evaluated for RT. However, at higher power input, the dimensionless average viscous dissipation in the blade swept volume was found to be similar for the HSI of two rings and the RT, corroborating the high local viscous dissipation of this HSI when operated at higher speeds.     

JYX高浓度黏稠物料加压旋转流变仪的研制

鉴于高浓度黏稠物料(如原生煤泥、城市污泥、造纸污泥等一类工业副产品或固体废弃物)若无添加剂作用在常压下是一种分散结团物质，流变参数测定过程中常出现被测介质“打滑”和容易“离析”等问题，研制出一种加压旋转流变仪(压力最高可达30MPa)，测量时将物料封闭加压，从而达到此类介质加压测量流变特性的目的。     

Oscillation of a tilted circular pad on a droplet for the self-alignment process

The seesaw-oscillation of a small circular pad on a single droplet was studied both numerically and experimentally. The circular pad with a diameter of 2.0–3.8 mm onto a water or glycerol droplet with a volume of 1–10 μL, and a bottom substrate with a smaller diameter than that of the pad were used in the experiment. The pad was then tilted and then the tilting fixture was quickly removed. The pad alternately oscillated and then finally stabilized in a horizontal position. The numerical model considering the surface tension and the viscous force of the droplet was developed and calculated using the same configurations as those in the experiment. The experimental and numerical data showed good agreement not only in terms of the oscillating frequency and damping ratio but the transient motion of the circular pad and instantaneous droplet surface shape.     

Wind-Induced Vibration Control for Substation Frame on Viscous Damper

In order to study the wind-induced vibration control effect of the viscous damper on the large-scale substation frame, this paper takes the large-scale 1000 kV substation frame of western Inner Mongolia as an example. The time-history sample of pulsating wind load is simulated by harmonic superposition method based on Matlab software. 6 kinds of viscous damper arrangement schemes have been designed, and SAP2000 finite element software is used for fine modeling and input wind speed time history load for nonlinear time history analysis. The displacement and acceleration of a typical node are the indicators of wind vibration control. The wind-induced vibration control effects of different schemes under different damping parameters have compared, and the damping parameters are analyzed for the optimal layout scheme. The results show that a viscous damper has installed in the lower layers of the substation; a viscous damper is placed between the ground column and the lattice beam. It is an integrated optimal solution. The wind-induced vibration control effect of the optimal scheme is sensitive to the viscous damper parameters, and the control effect does not increase linearly with the increase of the damping index and the damping coefficient. Corresponding to different damping indexes, the damping coefficient has a better range of values.     

Exact Analysis of Non-Linear Fractionalized Jeffrey Fluid. A Novel Approach of Atangana-Baleanu Fractional Model

It is a very difficult task for the researchers to find the exact solutions to mathematical problems that contain non-linear terms in the equation. Therefore, this article aims to investigate the viscous dissipation (VD) effect on the fractional model of Jeffrey fluid over a heated vertical flat plate that suddenly moves in its own plane. Based on the Atangana-Baleanu operator, the fractional model is developed from the fractional constitutive equations. VD is responsible for the non-linear behavior in the problem. Upon taking the Laplace and Fourier sine transforms, exact expressions have been obtained for momentum and energy equations. The influence of relative parameters on fluid flow and temperature distribution is shown graphically. As special cases, and for the sake of correctness, the corresponding results for second-grade fluid and Newtonian viscous fluid are also obtained. It is interesting to note that fractional parameter α provides more than one line as compared to the classical model. This effect represents the memory effect in the fluid which is not possible to elaborate by the classical model. It is also worth noting that the temperature profile of the generalized Jeffrey fluid rises for higher values of Eckert number which is due to the enthalpy difference of the boundary layer.     

中原油田原油复配破乳剂的研制

实验测定了南京金陵石化二厂等厂生产的8种破乳剂及复配破乳剂对中原油田卫城油矿稠油的脱水效果。这6种复配破乳剂脱水率高，脱水速度快，油水界面齐，与卫城油矿的缓蚀剂配伍性好。