Legacy Theses and Dissertations (1940-2009)
Permanent URI for this collectionhttps://hdl.handle.net/10657/6771
This collection gathers digitized University of Houston theses and dissertations dating from 1940.
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Browsing Legacy Theses and Dissertations (1940-2009) by Department "Chemical and Biomolecular Engineering, Department of"
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Item A cell for measuring the influence of magnetic field strength on the thermal conductivity of gases(1969) Elliot, Douglas Gene; Honeywell, Wallace I.; Prengle, Herman William, Jr.; Bannerot, Richard B.An apparatus is described for the determination of the influence of magnetic field strength on the thermal conductivity of gases. It was designed for use with an existing superconducting magnet system capable of field strengths from 0 to 100 Kg. Accordingly, a concentric cylinder type cell with axis parallel to the magnetic field was chosen as an optimum geometry. The design utilizes "cold finger type" cooling with a helium exchange gas reservoir and automatic temperature controller to maintain any selected temperature in the 77 to 300[degrees] Kelvin range. [...]Item A clinical and engineering evaluation of hypothermic fluidotherapy(1978) Diamond, Louis Ralph; Henley, Ernest J.; Huang, Chen-Jung; Kirkpatrick, C. V.; Everett, Robert L.A fluidized bed to deliver cold treatments was designed, built, and tested. Comparisons were made between this fluidotherapy unit and cold water. The effects on patient comfort, change in size of healthy feet, and the ability to remove heat were used as criteria. These tests were completed and the unit was taken to the University of Houston Athletic Department. Any traumatic foot or ankle injuries incurred by the members of the football team would have been treated. However the opportunity to make these treatments did not arise as there were no appropriate injuries during the trial period. [...]Item A clinical and engineering study on thermal therapy(1974) Ho, Purvis Ka-Kwong; Henley, Ernest J.; Flumerfelt, Raymond W.; Kay, Franklin J.A new heat modality was developed based upon the principles of fluidization. This design uses a fluidized airsolid system as the heat transfer medium in thermal therapy application. The new device known as the fluidotherapy unit is currently in use at St. Anthony Center, Houston, Texas, for clinical evaluations. Following the development of the fluidotherapy unit, an engineering and clinical assessment of three modalities in thermal therapy was carried out. The devices evaluated were a) the fluidotherapy unit, b) a whirlpool, and c) a paraffin wax/oil bath. The objective of the study was to compare their Relative effectiveness in delivering heat into a human hand. Steady state heat transfer in hand was considered rather than the transient heating. The amount of heat absorbed by a submerged hand in fifteen minutes were measured. The ratios were found to be 3.9 : 1.3 : 1.0; the fluidotherapy unit was observed to be the most effective heating device. In fifteen minutes, 17.2 Btu was delivered into a hand by the fluidotherapy unit, 5.6 Btu by the whirlpool, and 4.8 Btu by the paraffin. In addition to its relative high efficacy as a thermal therapeutic agent the fluidotherapy unit provides good patient motility. Finally a clinical study on the effects of prescription time on patient progress in rehabilitation was conducted. Active joint motions of patients were measured daily, the increase in joint motion was taken to represent the progress profile of a patient. Results obtained in this study were limited, but indicate that longer treatment times are beneficial.Item A computer model for the calculation of epicardial coronary blood flow(1985) Wiesner, Theodore F.; Nerem, R. M.; Flumerfeldt, R.W.; Chang, H.C.; Luss, DanThe model of epicardial coronary flow used here is one which includes the effects of branching as well as the nonlinear elastic properties of the artery walls. Branches are included on a discrete basis where at each branch point a mass balance and two momentum equations are written. These equations together with an additional equation, i.e., a lump impedance for each branch, determine the flow conditions in the region of branching. Between branch points, a tube is modeled as being straight and elastic in nature. The flow in each such tube of the arterial system is assumed to be that of an incompressible, Newtonian fluid whose motion can be adequately described using the unsteady, one-dimensional equations of motion. The effect of wall friction is specified through a friction factor, and the radial inertia of the tube and fluid is neglected. The elastic properties of the arteries exhibit themselves through an area-pressure relationship. These are entered through a specification of the propagation speed, c, of small amplitude pressure waves in an artery. With regard to boundary conditions, an upstream pressure is specified. The downstream boundary condition may be either specified as a pressure, if the artery continues as a finite branching system, or in terms of a terminal resistance and capacitance if the structure of the downstream region is modeled on a lumped basis. This model has been applied to the left coronary circulation which is modeled with epicardial coronary vessels having a discrete branching pattern. Each branch terminates in a lumped impedance which models the intramyocardial resistance of those vessels within the heart muscle. The upstream, driving pressure at the left coronary ostium is taken to be the aortic pressure, and the wavespeed in the coronary vessels is taken from in vivo measurements. Calculations have been carried out for both the dog and for man using geometry taken from measurements of coronary casts. Results have been obtained for the normal coronary circulation as well as for cases which include multiple stenoses and aorto-coronary bypasses.Item A correlation of friction factors for pipe flow over two-dimensional, periodic geometric roughness(1971) Gaddis, Emerson Clifford, Jr.; Worley, Frank L., Jr.; Dukler, A. E.; Dalton, Charles; Flumerfelt, Raymond W.; Hwang, Neddy H. C.Friction effects of two-dimensional, periodic, artificial roughness for fully roughened pipes in turbulent flow were investigated. Friction factor data over many different shapes, sizes, and spacings of roughness were compiled and examined for similarities which could be correlated. Such shapes included fins, round rods, rectangular rods, square bars, v- grooves, and sinusoids. It was found that friction factors for two differently- shaped roughness waveforms of the same spacing, amplitude, and pipe diameter are related by the normalized crosscorrelation coefficient of their waveforms. Such roughness falls into two groups: projections, where the bulk flow interacts with the flow near the wall; and grooves, where captive vortices exist in the roughness cavities and do not interact with the bulk flow. Friction factors were related to sine waves of similar size, modified by linear combinations of roughness dimensions and plotted versus a representing parameter R, which was found to be a dimensionless group containing a measure of spacing, amplitude, and pipe diameter. Two correlation plots were developed, for projections and grooves. These show distinct regions which are shown to delineate geometries where various wall flow processes occur. Predictions can thus be made of friction factor and flow type given only the roughness system geometry and shape.Item A CSTR measurement of high pressure catalytic methanation(1975) Hadjigeorghiou, Georghios A.; Richardson, James T.; Howell, John Reid; Luss, DanA continuous stirred tank reactor for high pressure catalytic methanation studies has been designed, built, and tested. Specifications, operating procedure, and limitations of the system are presented. This reactor is to be used to investigate the mechanism of the methanation reaction, as well as, to investigate the support effect on catalytic activity for various catalysts and supports. The kinetics of methanation over nickel catalyst were studied, in order to demonstrate the use of the reactor and to evaluate its performance. The operating region of the reactor, where prefect mixing prevails, was determined by pulse testing. External diffusional effects on the reaction rate were eliminated by running the reactor at high speed (determined experimentally) where such effects are absent. Intraparticle diffusional effects were eliminated by measuring effectiveness factors, which determines the maximum catalyst size. [...]Item A hybrid computer study of the dynamics of a tubular chemical reactor(1970) Lee, Hong-Mou; Motard, Rodolphe L.; Bannerot, Richard B.; Childs, S. Bart; Flumerfelt, Raymond W.; Honeywell, Wallace I.The stable hybrid computer solution of a time-dependent tubular chemical reactor represented by a system of parabolic or elliptic- parabolic partial differential equations is studied. In the classical approach to the serial hybrid solution of the one-dimensional diffusion equation using the continuous-space-discrete-time (CSDT) technique, there exists an undesirably large amount of positive analog loop feedback. This makes the classical hybrid method highly unstable in the study of higher frequency transient behavior. The serial decomposition method used in this study replaces the linear second order differential operator by two stable first order operators integrating in opposite directions and yields one-pass solutions instead of the usual iterative solutions. Thus, considerable computation economy can be expected. [...]Item A low temperature investigation of the effect of magnetic fields on the resistance characteristics of a thermistor(1969) Stein, Louis Edward; Honeywell, Wallace I.; Witte, Larry C.A low temperature, experimental study was conducted to determine the influence of magnetic fields on the resistance characteristics of a cryogenic Keystone Carbon thermistor. [...]Item A model of photochemical smog including gas-to-particle conversion for humid and dry climates(1978) Nicknish, Christine A.; Worley, Frank L., Jr.; Rabalais, J. Wayne; Payatakes, Alkiviades C.A model of photochemical smog is presented that includes the interaction of the gas phase molecules with aerosol particles. The model demonstrates how high relative humidity maintains the lower oxidant levels observed in humid climate cities such as Houston as compared to dry climate cities such as Los Angeles. A quasi-Langrangian approach is taken by modeling a homogeneous air parcel which follows an air trajectory. Four of the twenty species modeled are solved by the quasi steady state approximation (QSSA). The set of sixteen ordinary nonlinear stiff differential equations is solved by Michelsen's (1976) semi-implicit Runge-Kutta method. This numerical method directly handles the explicit time dependence of the emission rates, photodissociative reaction rates, and the empirically determined aerosol growth patterns. At high relative humidity there is an increase in the growth of aerosols resulting in a large available surface area for collision. The model assumes that certain molecular species that either directly or indirectly contribute to oxidant levels are partially removed through absorption by aerosols. Empirically determined aerosol growth patterns were presented for humid and dry climates. The humid versus dry climate aerosol growth patterns were compared under a variety of theoretical absorption conditions. Case studies included studying the effect of different combinations of molecules and radicals considered to be absorbed at various accommodation coefficients, the effect of initial concentrations of the species, and the effect of different emission rates. When only radicals were considered absorbed the model showed insignificant differences between the two types of aerosol growth patterns. When molecules as well as radicals were considered absorbed, oxidant levels were considerably lower for humid climate aerosol growth patterns under all conditions studied.Item A new model of the constricted unit cell type for granular porous media and collocation solution of the creeping Newtonian flow problem(1977) Neira, Mariano Alberto; Payatakes, Alkiviades C.; Bailey, James E.; Tiller, Frank M.; Wheeler, Lewis T.The constricted unit cell model for granular porous media developed by Payatakes, Tien and Turian (1973) is extended here to take in account the random orientation and interconnectivity of the flow channels. In the proposed model each unit cell corresponds to a pore (cavern) and has two coaxial constricted inlet and outlet ports ("throats"). The unit cells have random dimensions and orientations, the distributions of which can be determined from simple experimental measurements. The flow through a unit cell is assumed to be identical to that through a segment of the corresponding periodically constricted tube. A collocation solution of creeping newtonian flow through periodically constricted tubes is obtained. The profile of the wall of the type of tube considered is piecewise smooth, composed of symmetric parabolic segments and accords with the unit cell geometry of the porous media model. A transformation of the domain of interest into a rectangular one is obtained, which allows satisfaction of all boundary conditions. The collocation solution gives the stream function in terms of the new independent variables and can easily be converted to the original cylindrical coordinates. Axial velocity and radial velocity are obtained in analytical form, and the pressure drop is calculated both from integration of the energy dissipation function and of the Navier-Stokes equations. The results are compared with the finite-difference solution by Payatakes et al. (1973b) and are found in good agreement. Differences between the two solutions are attributed mainly to discretization error in the finite-difference solution. Based on the collocation solution, the new model is used to study the flow of fluids through granular randomly packed beds.. Experimental and theoretical predictions of permeability for two samples are compared and found in remarkable agreement. Intended applications of the model coupled with the present flow solution are in the modeling of processes taking place in the macroporous space of beds of monosized or nearly monosized grains (deep bed filtration, etc.). A modified version of this model will be applied to the modeling of secondary and tertiary oil recovery from oilbearing rocks.Item A numerical study of the displacement of fluids confined by parall plates(1974) Smith, Gene Stanford; Flumerfelt, Raymond W.; Tiller, Frank M.; Dalton, Charles; Henley, Ernest J.An investigation of the vertical displacement of one Newtonian fluid by another is reported. The fluids are immiscible, incompressible and contained by vertical parallel walls. The displacement process was numerically simulated with a computer algorithm (UHMAC) which solves the two-dimensional transient form of the Navier-Stokes equations by use of a modified form of the marker and cell method (MAC method). A comparison of the UHMAC results for the solution of an inlet flow problem and a confined wake problem indicate good agreement with the steady-state solutions obtained by other investigators. UHMAC results for a transient, two-phase problem (fractured diaphragm) were also quite good. The displacement process was simulated for several pairs of fluids with different density ratios and viscosity ratios. The effects of the density ratio and viscosity ratio on displacement efficiency were determined and compared with an approximate analytical solution given previously. The UHMAC results show that displacement efficiency increases as the ratio of the lower fluid density to the upper fluid density is increased. They also show that displacement efficiency increases as the ratio of lower fluid viscosity to upper fluid viscosity is increased. These results agree qualitatively with the results of the analytical solution. The simulation results also show that part of the upper phase fluid may be bypassed and left against the wall when the upper phase is more dense than the lower phase. The results, although limited to parallel plate geometry and Newtonian fluids, show the nature and importance of the variables involved in practical displacement problems such as oil and gas well completion operations.Item A preliminary study of gravity filtration(1977) Ah-Kee, Felix; Tiller, Frank M.; O'Neill, Michael W.; Bailey, James E.A methodology based on falling head gravity filtration was developed to allow cake filtration to be rapidly determined in the laboratory. Tests were run on talc and kaolin, and the effects of various filteraids on the filtration resistances of the two materials were studied. Plots of average filtration resistances versus mass fraction of filteraids in the solids mixture were found to fit a general equation for hyperbolas. I . Based on Shirato's Additive Law for ideal mixtures, an equation was developed to calculate the average filtration resistance of a mixture of two solids. The discrepancies between the experimental values of average filtration resistances and the corresponding ones calculated by means of the Additive Law increased with increasing lack of match between the particle size distributions of the two components. Calcium carbonate was unexpectedly found to act as a filteraid when mixed with talc, but not when mixed with kaolin. Calcium carbonate had low positive zeta potentials at pH values close to 7.0 and low negative zeta potentials at pH values above 8.1. Both kaolin and talc had nearly identical negative zeta potentials over a wide range of pH values (4.0 to 10.0). A study of scanning electron microscope pictures of talc and calcium carbonate mixtures revealed highly flocculated, irregular particles of calcium carbonate lodged between unevenly distributed, plate-like particles of talc. Although no information could be drawn about the relative sizes of the pores, it was apparent from the photomicrographs that some interaction had occurred which had changed the shape of the pores of the talc particles.Item A selective catalyst for the production of LPG from synthesis gas(1977) Santner, Chris R.; Richardson, James T.; Motard, Rodolphe L.; Howell, John ReidA study of the production of liquified petroleum gas (LPG) from the hydrogenation of CO over nickel catalysts is reported. Coprecipitated nickel alumina catalysts reduced between 300 [degrees] C and 400 [degrees] C are shown to have a high selectivity to LPG. Reactor temperatures of 275 [degrees] C to 310 [degrees] C give satisfactory conversion levels without sacrificing LPG yields. High contact times and a H2/CO ratio of two appears to be a good compromise between conversion, LPG production, and catalyst fouling. Magnetic studies to determine crystallite size distributions are reported. Lifetime studies for a nickel alumina catalyst (Catalyst A) show rapid deactivation initially down to 40% conversion where further deactivation is slow. Reduction temperature has no effect on this. Regeneration is possible with no loss of activity or selectivity. Temperature programming to maintain conversion is also possible with little sacrifice of selectivity. [...]Item A simulation method for predicting mass transfer in gas/liquid slug flow(1970) Dascher, Richard Emmett; Hubbard, Martin G.; Henley, Ernest J.; Reed, Ronald L.; Childs, S. BartA study was conducted for the purpose of collecting data and developing a mass transfer model for horizontal gas/liquid slug flow. The work was carried out in 1.5 inch pyrex flow channel using pure carbon dioxide and deionized water. The range of flow rates extended from 16 to 75 pounds per hour for gas and 4500 to 10,000 pounds per hour for the liquid. Liquid concentrations in the channel along with basic flow variables were measured and liquid phase mass transfer coefficients calculated. These were correlated with pressure drop in the channel and the curves closely followed the trends of other cocurrent mass transfer investigations, both in slug and non-slug flow. However, as with the previous slug flow work, a large amount of scatter existed in the correlation. It was shown that most of the scatter vras due to the inability of this type of a model to describe slug flow rather than to experimental error. [...]Item A study of effectiveness factors for reaction mixtures and pellets with non-uniform diffusivities(1970) Golikeri, Sudhir Vasant; Luss, Dan; Richardson, James T.; Wheeler, Lewis T.This work investigates the influence of internal diffusional and external mass transfer resistances on the effectiveness of porous catalyst pellets when many reactions proceed in parallel. The usual approach to this problem stems from the consideration of certain mean properties such as, the overall reaction rate and the mean effective diffusivity of the reacting species but completely neglects the effect of their distribution. In the present study, the effect of distribution of rate constants and diffusivities of various reacting species is considered and the result clearly demonstrates that the usual approach often misleads to higher effectiveness factor values. The asymptotic simplification of the effectiveness factor and the magnitude of the resulting errors is also discussed. In most works on the calculation of effectiveness factor for a single reaction, the effective diffusivity within a catalyst is assumed to be constant. However, the assumption is not valid when the catalyst exhibits a wide pore size distribution. Hence, a model that accounts for the variation of diffusivity with pore size is proposed to calculate the effective diffusivity of the reacting species. It correlates better with the values of diffusivities as back calculated from the reaction rates. Finally, the applicability of Petersen's criterion to neglect diffusional resistance in a catalyst is examined. It is shown that for certain kinetic expressions, the asymptotic solution of the effectiveness factor may deviate tremendously from its exact form.Item A study of integration algorithms in chemical and physiological system dynamics(1974) Castellanos, Francisco Sahagún; Motard, Rodolphe L.; Kay, Franklin J.; Flumerfelt, Raymond W.Solution of many chemical engineering problems requires the use of numerical integration techniques. The most popular integration technique for such problems is the classical fourth order Runge-Kutta that in some cases can be used only with very low efficiency. In the last few years new methods have been developed which seem to be efficient for regular and stiff problems. Some of these new methods were compared in the solution of chemical and physiological systems. The program written by C. W. Gear, which includes two slightly different algorithms for stiff systems and a third algorithm for regular systems was found to be the most stable and efficient in all cases.Item A study of the available correlations for predicting void fraction in cocurrent gas-liquid flow in conduits(1970) Bruce, Robert Sanford; Hubbard, Martin G.; Dukler, A. E.; Crump, Joseph R.The existing correlations for predicting void fraction in all orientations and regimes of cocurrent two-phase gas-liquid flow are surveyed, compared, and systematically classified. Guidelines for the selection of a correlation for a particular application are presented. Sources of data and physical models describing void fraction in cocurrent two-phase flow are listed. This information is presented as an aid to the potential user of the available correlations, and to the researcher who wishes to investigate specific areas of cocurrent two-phase flow where knowledge is lacking or incomplete.Item A study of the flow of particulate suspensions using a laser doppler velocimeter(1978) Steimke, John Lee; Dukler, A. E.; Anderson, Wallace L.; Hussain, A. K. M. Fazle; Worley, Frank L., Jr.; Motard, Rodolphe L.A study of the motion of droplets and particles suspended in a turbulent air flow was performed. A Laser Doppler Velocimeter (LDV) was designed and constructed for use in measuring two components of velocity for individual droplets or particles. The LDV could be used at any radial position in the pipe. As a check on the accuracy and reliability of the LDV method, LDV measurements were compared with hot wire anemometer measurements for the same flow conditions. For these verification experiments the seeding particles required by the LDV were chosen to be small enough that they precisely followed the air flow. In general, the agreement between the two types of measurements was very good. The LDV was also used, to measure the velocities of 20 ym dioctyl-phthalate droplets and 63 urn glass beads. A variety of statistics were generated. Theoretical predictions were made of the axial mean velocities, the axial root mean square velocities, and the radial root mean square velocities for the entrained particles. Fairly good agreement was observed between theory and data.Item A study of vertical turbulent film boiling and interfacial effects(1968) Coury, Glenn; Dukler, A. E.; Worley, Frank L., Jr.; Finch, Robert D.Theoretical and experimental studies were made of vertical, turbulent film boiling. The physical process is characterized by vapor moving within a thin, continuous vapor film next to a heated wall under the influence of buoyancy and pressure forces. Liquid in the bulk phase is separated from the heater wall by the vapor layer, but interfacial waves strongly influence the momentum and energy transport processes. It was shown that this complex process could be modeled mathematically by a two step analysis. First, a quasi-steady state model led to predictions of the heat transfer rates at any instant based on the velocity and temperature profiles that exist at that instant. The results of the quasi-steady state solution were then applied to the unsteady state condition, which is characterized by interfacial waves and a continually changing vapor film thickness, to determine the heat transfer rates at each instant of time. These results were averaged over time and space to give local and overall heat transfer rates expressed in dimensionless form. The analysis considers the effects of both the interfacial velocity and the interfacial roughness. The theory correlated data taken from systems where large waves were encountered and from relatively wave-free systems. Experimental measurements were made of the instantaneous, local surface heat flux by means of a low mass, surface thermocouple and a heat meter. Interfacial waves were found to be so large under some conditions as to cause occasional liquid-solid contact. Spectral analysis showed that the surface heat flux variations were random and caused by interfacial activity, and that the spectrum of these variations covered a broad frequency range from about 10 to 100 cps.Item A study of x-ray absorption factors for incident and detected beams of limited width(1970) Davis, Phillip W.; Honeywell, Wallace I.; Prengle, Herman William, Jr.; Motard, Rodolphe L.; Hayre, Harbhajan S.X-ray absorption factors are used to calculate the scattering intensities from a fluid sample by correcting the experimental intensities for the effect of absorption in the cell and sample. In the present study, a procedure is developed for calculating absorption factors when both the incident and detected beams are collimated to exclude portions of the sample-cell geometry. Previously, a procedure, developed by Kendig and Pings, was available to calculate absorption factors for the case when only the incident beam was collimated and the detected beam spanned the entire cross section of the experimental geometry. By extending this existing calculation technique to detected beams of limited width, additional amounts of the cell can be excluded from the geometry that contributes to beam absorption and beam scattering. Because of the low scattering power of fluids, reduction in the absorption of the incident and scattered radiation will increase the accuracy of the experiment. The calculation procedure is developed for absorption factors of cylindrical cells. A variety of experimental beam positions can be treated. Both the incident and detected beams can be positioned to increase or decrease the quantity of the sample or cell being scanned. [...]