超滤对血液透析传质性能的影响

本文对空心纤维型血液透析器中的传质过程进行了研究,提出了伴有超滤的血液透析过程中血液一侧传质的数学模型,并用分离变量法获得了该模型的分析解.实验数据表明,用该模型能较好地描述具有超滤的血液透析过程的传质机理.     

中空纤维膜低压超滤处理含油废水的数学模拟

提出一个不可忽略轴向压力降和膜渗透速率轴向变化的中空纤维膜低压超滤处理含油废水的传质模型 ,采用正交配点法并结合MATLAB软件进行模拟 ,解出速度分布和浓度分布 ,得到超滤速率的变化规律 ,与实验数据吻合很好 .用模拟结果讨论Peclet数对超滤的影响 ,并分析中空纤维丝内径向速度分布 ,为超滤膜及工艺条件的选择提供了重要依据 .     

表面活性剂在废水处理中的应用

综述了表面活性剂在废水处理中的应用技术--胶束增强超滤法和乳状液膜分离法.重点介绍了胶束增强超滤法和乳状液膜法的基本概念、传质机理和表面活性剂选取原则,总结了近年来胶团增强超滤和乳状液膜法在废水处理中应用的最新研究成果.胶束增强超滤法适用于单独或同时从废水中去除多价金属离子和带电荷的有机物,具有工艺简单,易于工业化的特点.乳状液膜分离技术综合了固体膜分离法和溶剂萃取法的特点,是一种新兴的节能型分离手段.     

环柱状催化剂内强放热复合反应──传质──传热耦合过程研究(Ⅲ)数学模型的求解及实验验证

采用有限元上的正交配置法对环柱状催化剂内强放热复合反应-传质-传热耦合过程二维数学模型进行了求解，计算结果与实验值十分吻合。     

环柱状催化剂内强放热复合反应──传质──传热耦合过程研究(Ⅲ)数学模型的求解及实验验证

采用有限元上的正交配置法对环柱状催化剂内强放热复合反应-传质-传热耦合过程二维数学模型进行了求解，计算结果与实验值十分吻合。     

柑桔汁超滤传质过程的研究

以"凝胶层阻力"及"渗透压阻力"理论为基础,根据柑桔汁在超滤过程中的通量变化规律,求出柑桔汁超滤过程的传质方程式,同时研究了操作压力对膜通量的影响,分析了造成传质阻力的主要因素,探讨了柑桔汁超滤过程的传质机理。     

血液透析、血液过滤与血液透析过滤传质动力学的通用模型

建立了中空纤维透析器中同时进行血液透析过滤时的简化二维传质模型,并进行了解析求解。该模型可以容易地扩展到血液透析和血液过滤。文中首次求出了血液过滤时的特征值。实验数据表明,该模型能较好地描述血液透析过滤过程的传质动力学。     

萃取柱内液-液两相流CFD-PBM模拟研究进展

对萃取柱内CFD-PBM模拟研究进行了较详细的综述,包括其基本理论、不同的求解方法及模拟研究现状等. CFD-PBM模拟的基本方程包括流动方程和群体平衡方程,其相互耦合,群体平衡方程涉及破碎与聚并2个关键模型. 群体平衡模型的求解方法包括直接离散化方法、矩量法、正交矩量法、直接正交矩量法、分段正交矩量法等,对这些方法的原理、优点和缺点进行了综述. 目前国际上关于萃取柱内CFD模拟采用较多的是简单的欧拉-欧拉两相流模拟,考虑液滴尺寸分布和进一步的浓度分布的群体平衡模型应用较少. 完善伴随传质的液-液分散体系的群体平衡模型,并将其应用于不同类型的萃取柱中,是萃取分离学科的重要任务.     

运动颗粒对传质过程影响的格子Boltzmann模拟

颗粒的主动运动对传质过程有重要影响.以表面恒浓度的二维球形颗粒为研究对象,采用耦合传质的格子Boltzmann方法(LBM)模拟了颗粒在自旋和振动两种情况下的相间传质过程.选择浸入运动边界法和非平衡态外推法处理运动颗粒边界,研究了颗粒自旋速度、颗粒振幅及振动频率对传质过程的影响.结果表明,中等雷诺数的自旋颗粒绕流中,随...     

大豆肽溶液超滤传质过程的研究

通过研究不同浓度的大豆肽溶液在超滤过程中的通量变化规律 ,根据凝胶层理论和渗透压理论 ,求出大豆肽溶液超滤过程的传质方程式 ,分析造成传质阻力的主要因素 ,并对大豆肽溶液在全回流超滤过程的透过机理进行描述。为超滤系统在大豆肽分离纯化过程中的膜通量计算提供一种有效的方法。     

Generalized linear driving force approximation for adsorption of multicomponent mixtures

This work deals with the development of efficient numerical tools for the solution of diffusion dominated parabolic partial differential equations. This study finds its application in the modeling of the intraparticle mass balance necessary for describing dynamic adsorption processes.The orthogonal collocation method is proposed as the basis for developing generalized linear driving force approximations for adsorption and desorption of multicomponent mixtures in a single particle, independently of the mass transport model adopted. Based on this approach, it was possible to derive some approximations previously obtained from the analytical series of the homogeneous diffusion equation.Orthogonal collocation is also compared to other numerical methods found in the literature, using both the homogeneous diffusion and the dusty-gas mass transport models. The results show that orthogonal collocation is the more consistent approach.     

Solving partial differential equations of gas–solid reactions by orthogonal collocation

In this work the solution of the coupled partial differential equations for noncatalytic gas–solid reactions has been considered by orthogonal collocation. First of all, by an integral transformation and then by applying the orthogonal collocation method, these partial differential equations are converted to the ordinary differential equations. Then the equations are solved and the conversion–time profiles are obtained. The solution of the equations for volume reaction model, grain model and grain model with product layer resistance, modified grain model, random pore model, nucleation model and reaction of two gas with one solid has been presented in this work. The orthogonal collocation is a rapid method for solving of these equations and shows a good accuracy with respect to other solution techniques in the literature.     

Simulation of packed-bed separation processes using orthogonal collocation

The two-point boundary value problem resulting from the heat and material balance equations of a packed separation column are solved using polynomial approximation techniques. The model equations are based on the two-film theory of mass transfer. The resulting partial differential equations are first reduced to ordinary differential equations and then integrated using semi-implicit Runge-Kutta method of integration. Application of orthogonal collocation simplifies the solution of the two-point boundary value problem. For the examples studied, the algorithm is found to converge rapidly with respect to the number of collocation points used in the polynomial approximation.     

Mathematical modeling of turbulent heat and mass transfer with chemical conversions

A transient model of heat and mass transfer with nonlinear sources (sinks) caused by first-and second-order chemical reactions is developed. The model uses a matching condition (equal temperature and local flux values) at the reaction zone-coolant interface. A finite-difference numerical solution to the problem is obtained using the alternating direction method. The model is tested by application to fast polymerization processes. The effect of the coolant velocity, reactor radius, and coolant temperature at the reactor inlet on the polymerization efficiency is studied.     

间歇反应器内固定化酶催化反应过程的模拟

<正>多孔载体固定化酶催化反应技术具有许多优点,在工业生产中的应用日益增多。大多数酶在固定化后,由于酶构象改变、分配效应和扩散限制等的影响,反应速率有所下降,其稳定性等亦发生变化。如何测定和定量表征这些性态,对酶催化反应器的设计和操作十分重要。     

POLARIZATION BEHAVIOR OF PACKED-BED ELECTRODES: A COMPARATIVE STUDY OF EXPERIMENTAL AND MODELING RESULTS

The current distribution and overall polarization behavior of electrodeposition at a flow-through (packed bed or fluidized bed) electrode are modeled by means of a one-dimensional model involving a primary reacting species and a simultaneous side reaction. The model equations are solved by orthogonal collocation; the time and storage requirements compare favorably to those of finite-difference methods. Experimental data obtained using a packed-bed electrode are compared with the model predictions and various methods of fitting the data are compared.     

POLARIZATION BEHAVIOR OF PACKED-BED ELECTRODES: A COMPARATIVE STUDY OF EXPERIMENTAL AND MODELING RESULTS

The current distribution and overall polarization behavior of electrodeposition at a flow-through (packed bed or fluidized bed) electrode are modeled by means of a one-dimensional model involving a primary reacting species and a simultaneous side reaction. The model equations are solved by orthogonal collocation; the time and storage requirements compare favorably to those of finite-difference methods. Experimental data obtained using a packed-bed electrode are compared with the model predictions and various methods of fitting the data are compared.     

活性炭纤维填充床内多组分竞争吸附

建立了活性炭纤维填充床内多组分竞争吸附传质动力学模型 ,采用正交配置方法求解数学模型以预测突破曲线 ,从理论上探讨了竞争吸附平衡及吸附质在填充床内的轴向弥散、纤维内扩散和纤维外对流传质等因素对强、弱吸附组分突破曲线的影响。在间歇和填充床吸附器内进行了脱除水溶液中酚类化合物的实验 ,测定了活性炭纤维吸附水溶液中苯酚和氯代苯酚的吸附等温线 (间歇吸附 )以及苯酚和氯代苯酚在活性炭纤维填充床内竞争吸附时的突破曲线 ,并与模型计算值进行了比较。结果表明 ,吸附质在活性炭纤维内扩散和纤维外对流传质阻力不是填充床内吸附过程的控制步骤 ,而轴向弥散影响显著 ,不可忽略     

Film‐surface diffusion during the adsorption of acid dyes onto activated carbon

A mass transport model has been developed and applied to the adsorption of three acid dyes onto activated carbon in three single component systems. The mass transfer model is based on two rate controlling mass transfer steps, namely external film mass transfer and homogeneous solid‐phase surface diffusion (HSD). Almost all previous film‐HSD models have been based on numerical solutions to the diffusion equation using orthogonal collocation or Crank–Nicolson finite difference solutions. However, in the present model a semi‐analytical solution to the solid surface diffusion equation is presented, yielding a sophisticated solution of the differential equations. The solutions provide a good correlation between the experimental concentration–time decay curves by incorporating the Langmuir equilibrium isotherm to describe the solid phase surface dye concentrations. However, the surface diffusivities show a dependence on the carbon particle surface coverage and these diffusivities have been correlated using a Darken relationship. Copyright © 2004 Society of Chemical Industry     

Drying of soybean seeds in a crossflow moving bed

The aim of this work was to investigate simultaneous heat and mass transfer between air and soybean seeds in a crossflow moving bed dryer. A model was developed from mass and energy conservation applied to the fluid and particulate phases. The equilibrium, heat transfer and mass transfer equations were taken from studies published earlier. Equations for drying kinetics were obtained from a thin layer study, and the equilibrium equation was chosen from rival model discrimination based on nonlinearity measures. The experimental part of this work involved the determination of air temperature distribution, grain moisture through the bed and air humidity at the bed outlet. The model equations were discretized by orthogonal collocation in the air flow direction. The resulting differential-algebraic equations were solved using a method based on backward differential formulas. Simulation results showed good agreement with experimental data.