Chemical Engineering Commons^™

Mathematical Modeling For Fabricating A Microstructure With A Pre-Specified Geometry Using Laser -Induced Chemical Vapor Deposition, Chaoyang Zhang

Doctoral Dissertations

Laser-induced chemical vapor deposition (LCVD) is an emerging new technique with many practical applications. To optimize the system for fabricating a microstructure with a pre-specified geometry in pyrolytic LCVD, a three-dimensional mathematical model is developed for predicting temperature distributions and laser dwell times across the substrate scanned by the laser beam. A microstructure is fabricated layer by layer, and for each layer the laser beam moves from one pixel to the next. The complicated correlations among temperature distribution, deposit growth rate, and laser dwell time are investigated. A purely heterogeneous reaction is assumed and any gas-phase transport is ignored.

A …

Gas-Viscous Liquid Behavior And Its Implications For Pressure-Relief Design, Ahmad H. Alramadneh

Doctoral Dissertations

The two-phase flow system is a multifaceted engineering task with many industrial applications. The accurate prediction of the behavior of such systems is of special importance.

This study is directed toward improving and integrating what is known about the gas-viscous liquid flow behavior during vessel depressurization, specifically, visually characterizing the top venting of saturated-viscous fluids. The experimental results are needed to improve the design methodologies for pressure-relief systems.

Lab-scale vessel depressurization experiments with initially saturated fluids were performed. In particular, a problem arose when sodium tetraborate decahydrate solution (model fluid) saturated with carbon dioxide gas is vented from a 5.3-liter …

Experimental Vapor-Liquid Equilibria Of Propyne With Propane, Propene And Propadiene, Edward Allen Kyser

Doctoral Dissertations

"Vapor pressures for pure propane, pure propene, impure propadiene and pure propyne and 19 binary mixtures of propane, propene, and propadiene with propyne are reported at -20, 5, 30, 55 and 80° C. An equation of state utilizing pure component saturated vapor and liquid densities is used to correlate all the data and the effect of the propadiene impurities was theoretically removed. The data of Burcham (1981) are recorrelated using new information about the impurities, and different results are obtained. Calculated relative volatilities and saturated densities are reported for the systems propane-propyne, propene-propyne, propadiene-propyne and propane-propadiene"-- Abstract, p. ii

Phase Equilibria From Pvt Measurements For Carbon Dioxide, Water And N-Decane, Michael Nduka Okafor

Doctoral Dissertations

"Phase equilibrium properties for the carbon dioxide - water - n-decane system were determined from pressure-temperature-volume (PVT) measurements. PVT properties were also obtained for pure carbon dioxide and water, and the binary mixtures of carbon dioxide - water and carbon dioxide - n-decane. The experiments were conducted at temperatures of 313.17, 353.15 and 393.15 Kelvin, and at pressures from 37 to 416 bar. Measurements for the mixtures were terminated when complete miscibility was observed.

The Perturbed-Hard-Chain (PHC) equation of state developed by Gmehling et al. (1979) was chosen to correlate the measured data because of its ability to handle the …

The Modeling And Analysis Of Multi-Component, Multivalent Biospecific Adsorption, Bo Henrik Arve

Doctoral Dissertations

"A general model is presented and used to predict the dynamic behavior of the adsorption, wash, and elution stages of biospecific adsorption (affinity chromatography) in finite bath and column operations. The model accounts for film and pore diffusional mass transfer resistances and the rates of interaction between adsorbates and ligands. For column operations the effect of axial dispersion in the flowing fluid stream is included. The model is applicable to single and multi-component biospecific as well as non-specific adsorption, and the adsorbates may be monovalent or multivalent. In the elution stage both non-selective and selective elution of monovalent adsorbates is …

Kinetics And Reactor Design In The Pyrolysis Of Tar Sands, Charles Arthur Lechner

Doctoral Dissertations

"Data from the thermal decomposition of bitumen from Utah tar sands was obtained and analysed with both isothermal and non-isothermal chemical reaction models. The use of a power rate law to describe the complex kinetics of pyrolysis gave agreement with the experimental data that was approximate, but adequate for design purposes. The results indicated a reaction rate that was second order in bitumen content, with an activation energy of about 17 to 20 kcal/gmol.

Data for the boiling point distribution of the products was consistent with a change of mechanism from vaporization to pyrolysis as the samples are heated. Higher …

The Modeling And Control Of Freeze Dryers, Martin James Millman

Doctoral Dissertations

"Two models of the freeze drying process were constructed and used to study various operational policies in order to determine the policy that would provide the shortest drying times.

The sublimation model which accounts only for the removal of frozen water, is found to predict shorter times for the free water removal phase than the sorption-sublimation model which properly accounts for the removal of frozen and bound water.

This study shows that the policy which produces the shortest free water removal phase, also produces the shortest overall drying time. This policy, predicted by both models, holds the chamber pressure at …

Fixed Bed Sorption With Recycle, John Thomas Casey

Doctoral Dissertations

"A mathematical model that describes single and multicomponent recycle-sorption systems is constructed. The model accounts for the generation of species by chemical reactions occurring in a single perfectly mixed tank, in the bulk fluid of the sorbent bed, and in the pores of the adsorbent particles.

Results are shown for single zeroth, first and second order reversible reactions as well as a network consisting of two first or second order reactions which may occur in series or parallel. For systems in which a single reaction occurs, both linear and non-linear equilibrium adsorption isotherms are considered. If multiple reactions occur, then …

Unsteady-State Cylindrical, Spherical And Linear Flow In Porous Media, Allan Jeffrey Anthony Joseph

Doctoral Dissertations

"The general problem of unsteady flow phenomena in porous media as considered in this investigation. Emphasis was placed upon the short-term flow characteristics within cylindrical, spherical and linear reservoir geometries, and practical analysis methods were developed for each problem. Additionally, nonlinear unsteady flow behavior in infinite reservoirs was considered. Each solution obtained could optionally be implemented by hand or computer, and several FORTRAN subprograms were also presented.

At present, the only way to analyze pressure transient data prior to the development of the "semi log straight line" is by type curve matching techniques. However, this study indicated that a reliable …

Gaseous Reactions In Heteroporous Media, Elmer Anthony Klavetter

Doctoral Dissertations

"A modified dusty-gas model which accounts for the effects the pore-size and tortuosity distributions have on the mass fluxes in heteroporous media is presented. The behavior of the dusty-gas model (homoporous model) can be obtained from the modified model when the pressure is either very low or very high as well as for intermediate pressures when the characteristic parameter of the introduced tortuosity function has a very small value. When the pressure is very high or very low, all pores in the porous medium are almost in a single transport regime of either molecular or Knudsen diffusion.

Comparisons of the …

A Development Of Regression Models For Predicting Two-Phase Relative Permeability In Consolidated Rock, Mehdi Honarpour

Doctoral Dissertations

"The primary objective of this study was the development of prediction equations for the water-oil imbibition relative permeability and gas-oil drainage relative permeability from experimental data.

Laboratory relative permeability data along with the corresponding rock and fluid properties were collected, and stepwise linear regression analysis was applied. Relative permeability models were developed in terms of rock and fluid properties.

The prediction models were tested against laboratory values and previously published correlations. It was found that the models developed in this study yield results that are generally in better agreement with experimental values than the previously published correlations"--Abstract p. ii

Cellulase Production By Fermentation With Trichoderma Viride On Cellulose And Wood Wastes, Nguyen Huu Kho

Doctoral Dissertations

"Cellulase production by the fungus Trichoderma viride QM 6a and the use of this cellulase for cellulose hydrolysis were studied using Solka Floc cellulose and waste wood (oak) as substrates. The fermentation produced higher enzyme concentration solutions with media containing additional amounts of soy peptone and KH₂PO₄.

The kinetics of fermentation in fermentors and shake flasks of Solka Floc and sawdust were investigated, and equations were selected to express the relationship of the rates of growth and enzyme production with cell mass, enzyme concentration and substrate remaining in the media.

Agitation and aeration decrease the enzyme …

Theoretical And Experimental Investigation Of Oil Recovery By The Electrothermic Technique, Samy Abdel-Hakeem El-Feky

Doctoral Dissertations

"This work investigates the feasibility of increasing oil recovery from petroleum reservoirs by the electrothermic technique. A mathematical model was developed for the prediction of reservoir response to heating by alternating electric current flow through the oil-bearing formations. The mathematical model was programmed in FORTRAN for solution on the IBM 370/168. The model used the finite difference technique to represent the differential equations that describe the system, and the sets of difference equations were solved by the Strongly Implicit Procedure (SIP) and Successive Overrelaxation (SOR).

In order to verify the mathematical model, a set of experiments was conducted to determine …

Optimal Process Overdesign With A Flowsheet Simulator, Frank Joseph Doering

Doctoral Dissertations

"Overdesign is applied to chemical processes to include additional equipment for improved process reliability or to account for deviations from average conditions. An efficient method to optimize the overdesign of a complex chemical process is developed for use on a flowsheet simulation program. The effectiveness of the method is demonstrated by simulating the sulfuric acid process with metallurgical feed gas on the flowsheet program PROPS. The process is optimized for reliable and variable performance by the adaptive random search algorithm"-- Abstract, p. xi

Simulation Of Nonisothermal Absorber-Reactors For Multicomponent Systems, Robert E. Schwab

Doctoral Dissertations

"There are various models available for calculations involving one transferring component with chemical reaction for isothermal conditions using linear equilibrium data. However, the differential equations for multicomponent mass and energy transfer with chemical reaction have not been developed or implemented. This work demonstrates the development of a reliable model describing multicomponent mass and energy transfer in a continuous two-phase absorber-reactor for Non isothermal conditions and demonstrates the feasibility of solving the differential equations numerically. The numerical solution, using nonlinear equilibrium data, is used to obtain the absorber-reactor column specifications"-- Abstract, p. 2

Split-Film Anemometry In A Drag-Reducing Solution, Jack Chosnek

Doctoral Dissertations

"Turbulence measurements were made in the tube flow of mineral oil and a 0.2% solution of polyisobutylene in the same oil. Velocity profiles, axial and radial turbulence intensities, and axial and radial energy spectra were obtained in both fluids using a split-film anemometer probe. In addition, velocity profiles and axial turbulence intensities were obtained in oil using a 0.001-in. cylinder probe, a cone probe and a parabolic-wedge probe. The measurements were made in a one-inch tube at a constant fluid temperature of 30.0°C, in the Reynolds-number range of 4,800 to 50,000.

Four factors influenced the results in a greater manner …

Process Optimization By Flow Sheet Simulation, Larry Dale Gaines

Doctoral Dissertations

"PROPS, (Process Optimization System), has been used to simulate and optimize the Universal Oil Products solid phosphoric acid catalyst process for producing gasoline. PROPS, a modified version of CHESS (Chemical Engineering Simulation System), performs a complete design and economic evaluation of the process for each set of independent variables. The computational time during optimization was reduced by the use of a regression equation to determine K-values as a function of temperature and pressure. K-value data used for the regression was generated from the Chao-Seader correlation using mixtures of the gasoline components to be encountered during optimization. The regression equation produces …

Anionic Polymerization Of A Series Of Cyclocarbosiloxanes, William W. Knickmeyer

Doctoral Dissertations

"A study has been made on the anionic polymerization of a series of cyclocarbosiloxanes of the type: [IMAGE] where n was varied from 2 to 8. The polymerization reaction in benzene, was initiated using cesium trihexyl silanolate, a unique organic soluble liquid catalysts. Benzene served as both a solvent and to shift the position of the NMR SiCH₃ polymer peak away from the monomer peak making it feasible to follow the kinetics on a Varian EM-360 Nuclear Magnetic Resonance Spectrometer. Hexamethylphosphoramide (HMPA) was used as a promoter to solvate the initiator ions and thus increasing the polymerization rate. It …

In Vitro Studies Of Lipid Uptake By Medical Grade Silicone Rubbers Used For Heart Valve Balls, Shu Hua Wu

Doctoral Dissertations

"Various chemical and physical aspects of high lipid absorption by medical grade silicone rubber and the dynamic mechanical properties of lipid-rubber systems were studied in order to provide an insight into the problem of 'variance' of these materials when subjected to 'in vitro' and 'in vivo' environments. Wide variations of post cure procedures of the silicone rubber were studied. Different post cures did not appreciably affect the mechanical properties of the silicone rubber. Mass transfer studies demonstrated that the diffusion of linolenic acid into a silicone rubber slab is a purely physical diffusion process (D = 3.2 x 10^{-3 …}

Transition Boiling Of Normal Pentane From A Horizontal Flat Gold Surface, Ronald M. Canon

Doctoral Dissertations

"The characteristic boiling curve for Normal Pentane was determined at 1 atmosphere pressure with particular attention devoted to the transition boiling region. The heat transfer surface was a horizontal, gold-plated, copper disc.

Stability analysis was employed to demonstrate why previous investigators have had only limited success in collecting data in the transition region and to provide a valid basis for equipment designed to operate in this region.

A method of predicting the transition region boiling curve from the nucleate curve and the Liedenfrost point is presented. The method was found to predict the transition boiling of Normal Pentane, Freon 12, …

Mathematical Simulation Of Gas And Water Coning In Petroleum Reservoirs By The Dynamic Material Balance Technique, Visheshwar Nath Simlote

Doctoral Dissertations

"The prediction of coning behavior at a producing oil well is one of the most difficult numerical simulation problems. Because of the convergent flow patterns and small sizes of the inner grid blocks, the radial coordinate models used to study the problem have a tendency to become unstable. Since several hundred pore volumes may flow through the inner grid blocks during a rather small time interval, instabilities are likely to occur in the saturation calculations for these grid blocks. The dynamic approach to saturation calculations is a method which first computes the correct material balance and then calculates the saturation …

Nucleate Boiling Of N-Pentane, N-Hexane And Several Mixtures Of The Two From Various Tube Arrays, Kenneth Wayne Wall

Doctoral Dissertations

"An investigation of nucleate boiling heat transfer in saturated pools of Normal Pentane, Normal Hexane and several mixtures of the two was conducted. The fluids were boiled from gold-plated, copper, cylindrical heat transfer surfaces, 4.96 inches long, and 1.048 inch in diameter. The heat transfer elements were boiled in varying vertical tube arrays at a pressure of 14.70 psia.

It was found that the mixtures boiled with a lower heat transfer coefficient than that for either pure component when boiled alone. When boiling in any of the tube bundle arrangements, the heat transfer coefficients for the upper tubes in the …

Hydrodynamic Mixing Model Applied To A Continuous Stirred-Tank Reactor With And Without Second-Order Reaction, Leon L. Otte

Doctoral Dissertations

Paper 1: "A hydrodynamic mixing (HDM) model, used to calculate the steady-state spatial distribution of conversion for a second-order reaction in a continuous stirred-tank reactor (CSTR) for non-premixed reactants was developed and contrasted with other methods. The HDM model is based on a segmental description of the reactor and includes turbulent mixing effects in each segment. As a test of the model, the experimental results obtained from a tubular reactor were found to be very well represented for a range of reactant ratios. Spatial distributions of concentration and segregation intensity (degree of mixing) within the CSTR were determined for a …

A Study Of Exothermic Chemical Reaction In A Porous Catalyst Wedge, Joseph Michael Schardl Jr.

Doctoral Dissertations

"Temperature and composition were measured at various locations in a system where ethylene is hydrogenated to ethane on a 1/4 inch porous catalyst wedge made of nickel supported on alumina. 'When the wedge of catalyst was bathed in hydrogen, experimental results indicated a high temperature rise from the feed temperature to the catalyst which is implied by the diffusion controlled regime for solid catalyzed, highly exothermic reactions. This high activity was reversibly reduced by bathing the catalyst wedge in nitrogen for extended time periods (greater than 24 hours). This nitrogen soaking changed the experimental conditions from those of diffusion controlled …

Nucleate Boiling From Polymer Coated Surfaces., David Franklin Warner

Doctoral Dissertations

"This study consisted of an examination of both the effects of nucleate boiling on polymer coated surfaces and the effects of the polymer coated surfaces on the nucleate boiling curve. The nucleate boiling curve (the curve resulting from plotting heat transferred per unit area versus the temperature difference between the boiling surface and the liquid pool) of the polymer coated surfaces were compared with the nucleate boiling curve of gold-plated surfaces with no polymer coat and it was found that the thicker the polymer coat, the more the curve deviated from that of the metal uncoated surfaces.

All surfaces were …

Convergence Of Material Balance In Mathematical Simulation Of Petroleum Reservoirs, Abdul Rashid Merchant

Doctoral Dissertations

One criterion for determining the precision of pressures calculated by a simulation model is the accuracy of the material balance. A high degree of precision in the calculated pressures is a necessary condition for elimination of error in prediction of fluid migration in the reservoir. However, this condition is not sufficient to guarantee accuracy of the simulation, since inaccuracies are introduced by truncation errors, machine round-off errors, and by the use of finite difference approximations to represent nonlinear partial differential equations.

A new procedure called Error Matrix Technique has been developed for reduction of material balance errors. This reduction is …

Numerical Simulation Of Individual Wells In A Field Simulation Model, Ali Mohammed Akbar

Doctoral Dissertations

"Conventional numerical simulation of hydrocarbon reservoirs is inadequate for the prediction of bottom-hole pressures at production wells. This problem can be overcome by using a special mathematical model which combines individual well simulation with reservoir simulation. Severe computational instability is commonly encountered in the radial models due to the relatively small grid-blocks and high fluid velocities in the vicinity of the well bore. This instability is found to be more pronounced during depletion of the reservoir when the pressure near the well bore is below bubble-point pressure. A new technique is introduced here for saturation calculations in the critical region …

Electro-Reduction Of Bromate On Mercury, Jaw-Shin Chang

Doctoral Dissertations

"The electrochemical reduction of BrO⁻₃ was studied on a stationary Hg electrode in neutral and basic solutions containing K⁺, Na⁺, and L⁺. Coulombic efficiency studies showed Br⁻ to be the predominant reduction product. The steady state kinetic parameters include Tafel slopes of ca. -0.120 V, approximate first order activity dependences for both BrO⁻₃ and the accompanying cation, and no pH dependence. A reaction scheme is proposed which involves BrO⁻₃ "bridged" to the electrode by the accompanying cation. It is suggested that the "bridging" is a result of ion-pairing in the electrical double-layer"--Abstract, page 1.

Film Boiling Of Freon 113, Normal Pentane, Cyclopentane, And Benzene From Cylindrical Surfaces At Moderate Pressures, Gary Joseph Capone

Doctoral Dissertations

"An investigation of film boiling heat transfer in saturated pools of liquid Freon 113, Normal Pentane, Cyclopentane, and Benzene was made. The fluids were boiled from copper, cylindrical heat transfer surfaces, 3 inches long, and 0.55, 0.75, and 1.00 inch in diameter. The heat transfer elements were positioned horizontally in an autoclave and tested at moderate pressures of up to a pressure of 242.5 psia for Normal Pentane.

The experimental data are discussed and compared with known film boiling correlations. The known correlations were found to be inadequate in predicting heat transfer coefficients as a function of pressure, temperature difference …

An Application Of Residual Relaxation To Mathematical Simulation Of Petroleum Reservoirs, Grufron Achmad

Doctoral Dissertations

"Stability and convergence have long been primary concerns in the application of numerical techniques to the simulation of petroleum reservoir performance. An iterative method based on sequentially reducing the residual to zero at each grid point has been developed. It has been shown analytically that this residual relaxation method is stable, convergent, and consistent.

A three-phase areal model was developed to simulate a hypothetical homogeneous petroleum reservoir, and various computational methods were tested with this model. The residual relaxation method developed in this study (RELAX) was found to converge as rapidly as SIP, and much faster than either LSOR or …