Automation of Vapour Pressure Osmometry measurements

A program has been developed for the control of Vapour Pressure Osmometry (VPO) measurements. The output signal of a Vapour Pressure Osmometer is read by an A/D converter card installed in one of the expansion slots of a PC microcomputer. The stability of the measurements is checked by analysing the first derivative of the smoothed signals, which is calculated in real time. Sets of repeated measurements are carried out under the supervision of a computer program as a check for their reproducibility. When the set is ended the program calculates the average and its standard deviation.The program is particularly valuable for evaluating VPO measurements for solution equilibria studies. This interfacing strategy may be applied to any kind of technique in which the time stability of the signals is the basis for defining measurement stability. The automated VPO has other advantages, including low cost and time saving.     

喷雾场多参数层析算法的仿真效验与实验测量

根据层析技术原理,对喷雾雾滴粒径和浓度的空间分布开展了研究,并编制了喷雾粒径和浓度层析计算程序.对给定粒径和浓度空间分布的喷雾场,根据脉动法测量原理在计算机上仿真了雾滴粒径和浓度的线投影值,根据仿真的投影值重建了雾滴粒径和浓度的空间分布,重建结果与给定的分布结果完全吻合.在喷雾实验台上用光脉动法装置测量了喷雾雾滴粒径和浓度的线投影值,并用编制的程序对喷雾雾滴粒径和浓度的空间分布进行了层析计算.     

管壳式换热器及其强化传热的(火用)经济评价和优化

本文以管壳式换热器的第二定律分析和(?)经济评价为基础,提出了换热器费用方程。以此方程为目标函数,解出了管壳侧同时优化的参数,并开发了相应的可用于设计的优化选型程序,进而导出了最优传热温差关系式。     

An Accurate Numerical Solution of Biospecific Adsorption in a Stirred Bath

Abstract

A mathematical model describing the kinetics of a biospecific adsorption process (affinity chromatography) in a stirred finite bath has been numerically solved by an efficient computer program. The radial adsorption distribution of β-galactosidase onto immobilized anti-β-galactosidase for different times obtained from the present solution has been satisfactorily compared with previously published experimental data, as well as with the theoretical predictions of Chase's and Arve's models. It is also shown that the present solution is more accurate than the one obtained by Chase. The computer program used in this study is a general one that can be used for any number of solutes and for equilibrium and nonequilibrium conditions.     

Reactive Extraction of Levulinic Acid Using TPA in Toluene Solution: LSER Modeling,Kinetic and Equilibrium Studies

Abstract

Levulinic acid, a carboxylic acid containing ketone structure, is a clear to brownish semi‐solid melting at 37°C; soluble in alcohol, ether, and chloroform, levulinic acid can be used as an acidulant in foods and beverages. Organic solutions of amines are being used increasingly to separate organic acids from aqueous mixture solutions by reactive extraction. The design of an amine extraction process requires kinetic data for the acid–amine+solvent system used. Kinetic studies for the extraction of levulinic acid from aqueous solution with tripropylamine (TPA) diluted in toluene were carried out using a stirred cell for kinetic studies. Equilibria for levulinic acid extraction by TPA in toluene as a diluent have been determined. All measurements were carried out at 298.15 K. The equilibrium data were also interpreted by a proposed mechanism of complexation by which (1∶1) and (2∶1) acid‐amine complexes are formed. Kinetics of extraction of levulinic acid by TPA in toluene has also been determined. The results of the liquid‐liquid equilibrium measurements were correlated by a linear solvation energy relationship (LSER).     

Chemical absorption of mercaptan in an aerosol operated loop reactor

A mechanistic mathematical model for the chemical absorption of mercaptan in sodium hypochlorite solution has been derived. In order to describe the process adequately, a semi-verified complex scheme of the involved kinetic reactions based on stopped-flow measurements with UV-detection has been implemented. The overall system of differential equations has been solved numerically. For some asymptotic cases, approximation formulae are given. The process has been carried out in an aerosol operated jet loop reactor which is characterized by high interfacial areas at low liquid flow rates. Fitting the model solution to the experimentally obtained conversion data enabled determination of the unknown hydrodynamic parameters. By means of a sensitivity analysis, the influences of the different parameters are discussed.     

Analysis of oilfield waters by ion chromatography to determine the composition of scale deposition

Large amounts of water are produced during the production of crude oil and natural gas. This water has to be analyzed to realize the correct geological formation. In this work, an extensive analysis of oil field water delivered from Gulf of Suez was carried out to determine the composition of the precipitate formed before starting waterflood operation. Cation and anions are the main interest of this analysis and are carried out using ion chromatography (IC). The data of water analysis have been used as an input data for computer software program. The scale precipitation processes in the bulk solution as well as the tendency rate and inhibitor effectiveness have been determined using jar test methods. The data arising from jar test are compared with the output of the software program to evaluate and quantify the scale precipitation. Also, the mixing waters are analyzed after precipitation to determine the consumed calcium and sulfate ions in presence and absence of inhibitor. It was found that mixing of the injection water and formation water leads to calcium carbonate and barium sulfate scaling at 60% formation water in absence of scale inhibitor.     

挥发性弱电解质水溶液三元系的汽液平衡——NH_3-CO_2-H_2O,NH_3-H_2S-H_2O,NH_3-SO_2-H_2O体系

在Edwards通用性分子热力学模型中增加了三元相互作用项,应用优化若干可调参数的方法研究了弱电解质水溶液三元系的汽液平衡.编制了通用性FORTRAN计算程序PARA_9,在TQ-16机上实施.该程序具有弹性功能:可以直接计算,亦可优化参数.对NH_3-CO_2-H_2O、NH_3-H_2S-H_2O、NH_3-SO_2-H_2O三个体系进行处理获得满意结果,平均相对误差5—10%.同时给出了几组可调参数数值,并得到了溶液中离子和分子的活度系数,平衡浓度等有价值的信息.     

Statistical Investigation on the Quantitative Determination of Enzymes in Detergent Powders by Automatic Analysis

A statistical investigation has been carried out on the accuracy and precision of the analytical method of automatic determination of enzymes in detergent powders. The statistical design may be applied to any investigation in which the optimizing of the number of trials is required as a function of the wanted precision and supportable costs. A table, that reports the half-range, as a percentage, of the 95% confidence interval on the base of the concentration values of the enzyme and carried out samplings, has been obtained. By means of this table and with suitable interpolations, every operator may fix beforehand the number of samples to examine, if a certain precision must be obtained, or conversely the range of the confidence interval got on the base of the number of samplings. The experimental data have been elaborated by a desk computer, introducing in the machine the resulting absorbance values.     

Analysis of EXAFS data on bimetallic clusters

In previous studies of the structures of bimetallic clusters using extended X-ray absorption fine structure (EXAFS), structural parameters were determined by fitting the single scattering expression for EXAFS to experimental data associated with an absorption edge of each component. The data for the two edges were fitted separately. Recently, with an extensive modification of the computer program for the analysis of EXAFS data, it has been possible to fit the EXAFS data for the two edges simultaneously. This improved method of analysis has the feature thatall of the EXAFS data are used in the determination ofall of the structural parameters, and permits one to impose in a direct manner certain necessary physical conditions regarding the system. Consequently, one has greater confidence in the values obtained for the parameters. The present paper first summarizes published results obtained by the previous method of analysis on a number of systems. For comparison, a summary is then given of results obtained from the same data on these systems with the new method of analysis.     

Electrical characterization of NF membranes. A modified model with charge variation along the pores

Nanofiltration rejection measurements have been performed for KCl solutions to characterize a non-commercial NF membrane. Membrane Potential (MP) and Tangential Streaming Potential (TSP) measurements have also been carried out for a wide range of concentrations. The charge of the membrane and the pore dielectric constant has been obtained as functions of the salt concentration from these three ensembles of experiments, showing a fair agreement.For the data treatment, two modifications of the Steric Electric and Dielectric Exclusion (SEDE) model have been proposed to allow the electrical characterization of the NF membrane: (1) the volumetric charge density is considered to change along the pores by means of the inclusion of a charge isotherm (which correlates the membrane charge with the ion concentration) in the transport equations, and (2) the porous support is considered by the inclusion of the adequate transport equations similarly to how the active layer is considered.     

The compatibility of the polystyrene/acrylonitrile-butadiene-styrene grafted copolymer system

Summary The study of polystyrene (PS)/acrylonitrile-butadiene-styrene (ABS) grafted copolymer/cyclohexanone or methylene chloride system compatibility both in concentrated solutions and solid state has been carried out by phase separation, viscosimetrical measurements and thermal behaviour.Having in view the obtained data it has been ascertained that the systems present different degrees of compatibility depending on the mixtures composition. At higher temperatures, the compatibility of the components is changed.     

A numerical model for single screw extrusion with poly(vinyl chloride) (PVC) resins

A computer model has been developed to simulate the behavior of molten polymer in the melt conveying zone of extruders. This model, based on a hybrid finite difference/finite element resolution of the equations of change governing momentum and heat transfer, allows the prediction of the pressure profile while accounting for wall end effects as well as the solid bed velocity. Simulation results are compared with analytical and finite difference method results found in the literature. A fairly good agreement is obtained in the case of low density polyethylene. Numerical tests are also carried out with rigid poly(vinyl chloride) compound used for window profile extrusion. The good agreement found between the predictions and experimental measurements obtained on an industrial extruder confirms the performance of the proposed model.     

Membrane inflation of polymeric materials: Experiments and finite element simulations

A high‐speed optical measurement system, which is capable of measuring transient surface shape, is used in the polymer membrane inflation experiments. The accurate measurement data, which is an array of points, with known Cartesian coordinates and with respect to a fixed coordinate system, provides a source for further bubble shape analysis. Inflation pressure is correlated with each bubble shape measurement. The measured results reveal the importance of the thermal warpage and temperature gradient in the bubble inflation tests. Potential errors in the material parameter calculation, which are caused by assuming uniform temperature and zero thermal warpage, are pointed out. Consequently, a finite element analysis has been carried out to simulate the membrane inflation with/without thermal warpage and the temperature gradient. The material parameters obtained considering the thermal warpage and temperature gradient yield improved agreement with the experimental data. Although in this paper the measurement data is mainly used for the determination of the material parameters in the bubble inflation tests, they are also a source of validating other computer‐aided simulations as well as in the study of the thermal shrinkage of polymer products.     

Numerical simulation of turbulent batch mixing in a vessel agitated by a Rushton turbine

In this study, computational fluid dynamics (CFD) modelling of turbulent batch mixing of an inert tracer in a baffled vessel agitated by a six-bladed Rushton turbine has been carried out using the proprietary code FLUENT. The study is intended to evaluate the CFD predictions of key properties related to the mixing against measurements and to provide a detailed insight into the process. Three-dimensional, time-dependent flow and mixing calculations have been performed using the fully predictive sliding-mesh technique for the impeller/tank geometry employed by Distelhoff et al. [M.F.W. Distelhoff, A.J. Marquis, J.M. Nouri, J.H. Whitelaw, Scalar mixing measurements in batch operated stirred tanks, Can. J. Chem. Eng. 75 (1997) 641–652] for mixing studies using a laser induced fluorescence technique. Complementary validation of hydrodynamic predictions in a geometrically similar tank was carried out against the experimental data obtained by Hockey [R.M. Hockey, Turbulent Newtonian and non-Newtonian flows in a stirred reactor, Ph.D. Thesis, Imperial College, London, 1990]. The predicted mean velocity components in the bulk regions of the tank above and below the impeller compare well with the experimental data. However, the turbulent kinetic energy is significantly underestimated in these areas. The predicted tracer concentration variations with time at different locations in the tank, in common with measurements, show initial fluctuations, which eventually approach the fully mixed concentration. However, the time required for the appearance of first peak in the concentration–time plot, peak value of the tracer concentration and the time required for the local tracer concentration to attain the final value depend on the position in the tank. The CFD predicted mixing times at different locations in the tank as well as the overall mixing time show reasonably good agreement with the measured data and with those calculated from published experimental correlations.     

Coflotation Separation for the Determination of Heavy Metals in Water Using Colloidal Gas Aphrons Systems

Abstract

The separation and preconcentration of metal traces using CGA in connection with coflotation processes is described. A 4:1 mixture of anionic surfactants consisting of sodium dodecylsulfate and potassium oleate has been used to generate the CGA system, and Fe(OH)₃ has been used as a collector. The separation process has been optimized using the Simplex Method (COFLOT computer program) complemented with a factorial design to investigate the influence of the different parameters in the investigated process. The results obtained evidenced recovery yields over 90% for the elements investigated (Cu, Co, Cd, and Ni), implying flotation times under 5 minutes as applied to samples of varying salinity, concentration, and volume.     

A model for the thermal and chemorheological behavior of thermosets. I: Processing of epoxy-based composites

The rheological and thermokinetic aspects of the cure of epoxy based composite laminates are analyzed by means of a computer program developed using the heat transfer and heat generating characteristics of a polymerizable system. In particular, the temperature and degree of cure influence on the resin viscosity have been first considered, then the temperature profiles, calculated according to an appropriate kinetic and heat transfer modeling, have been used to predict the corresponding viscosity profiles. Molecular and thermocalorimetric parameters are used for the prediction of the theoretical chemorheological behavior. Commercial epoxy systems commonly used in the preparation of carbon fiber laminates have been characterized by Differential Scanning Calorimetry (DSC) and dynamic viscosity measurements and the results are compared with the theoretically predicted values.     

Means of escape - 1988. How close are we to modelling egress from buildings in fire?

During the last twenty years a number design methods for calculating the movement of people in buildings have been developed. This presentation briefly reviews some of these modelling efforts. Furthermore, it discusses some aspects of the pedestrian movement and addresses an egress model based on the data provided by Predtechenskii and Milinski. This model is applicable to the evacuation of multi-storey buildings via staircases and predicts the flow movement in terms of time with regard to the building's layout and the interdependencies between adjacent egress way on this model, written in GWBasic language for any IBM-compatible personal computer. The program is built up as a dialogue between the user and the computer, where the escape route configurations (the width and the length of each section) as well as the number of the persons are put gradually during the course of the computation. The program enables the user to change the dimensions of the building's means of escape and the occupant load easily and work out the influence of the variation on the complete circulation system. Recently, the program also calculates the flow movement under decreased visibility conditions on smoke filled escape routes based on japanese measurements about the walking speed of pedestrians in fire smoke.     

脉冲筛板萃取柱中传质过程的研究

在内径40mm实验脉冲筛板柱中,用30%磷酸三丁酯-硝酸-水体系测定了各种操作条件下两相稳态传质浓度剖面、液滴直径分布和分散相体积分数.根据多级返流模型拟合实际浓度剖面推算得到真实的体积传质系数K_(oDa)和两相返混参数,并进而计算出相际传质系数K_(oD).对标准板和分散-聚合型板两种柱结构内的传质过程进行了分析和讨论.研究结果表明,在本实验范围内,脉冲筛板柱内相际传质系数可按单液滴湍流内循环传质模型来预测.     

V-L EQUILIBRIUM OF WEAK ELECTROLYTE SOLUTION OF THE NH_3-CO2-H_2O,NH_3-H_2S-H_2O AND NH_3-SO_2-H_2O SYSTEM

In this paper we have systematically studied V-L equilibrium in ternary aqueous solutions containingvolatile electrolytes by introducing a ternary interaction term into Edwards generalized molecular thermody-namic model and optimizing several adjustable parameters.The program PARA9 with flexible functions ofdoing a series of calculations has been developed and carried out on a TQ-16 computer.It can be usedeither for directly calculating the V-L equilibrium or for optimizing the adjustable parameters.For the sys-toms(NH_3-CO_3-H_2O_3,NH_3-H_2S-H_2O and NH_3-SO_2-H_2O)satisfactory results have been obtained withrelative mean deviation of 5-10%.Besides,several sets of adjustable parameters and valuable information ofactivity coefficients,equilibrium concentrations of ions and molecules in solutions are obtained.