M.S. Theses

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The influence of lactic acid on the rate of absorption of premetallized dyes on untanned proteinic tissue
(Thesis (M.S.)- Robert College. Institute for Graduate Studies in Science and Engineering, 1964., 1964.) Fricke, Winfried S.; Noyan, Turgut.
Pozzolan of Çanakkale
(Thesis (M.S.)- Robert College. Institute for Graduate Studies in Science and Engineering, 1966., 1966.) Orhon, Gültekin.
Beneficiation of the oolitic mineral of the Çamdağ iron deposits
(Thesis (M.S.) - Robert College. Faculty of Graduate School of Engineering, 1967., 1967.) Dereboylu, Günseli.; Noyan, Turgut.
Growth of protein-rich micro-organisms in petroleum
(Thesis (M.S.) - Robert College. Faculty of Graduate School of Engineering, 1967., 1967.) Bilgin, Ömer.; Noyan, Turgut.
The use of perlite in the manufacture of oxychloride cement compositions
(Thesis (M.S.)- Robert College. Institute for Graduate Studies in Science and Engineering, 1967., 1967.) Natan, İsak.; Noyan, Turgut.
Activation of some Turkish clays to be used in bleaching of edible oils
(Thesis (M.S.) - Robert College. Faculty of Graduate School of Engineering, 1968., 1968.) Taner, Meral.; Noyan, Turgut.
A study on the production of antimony trioxide from its ores by volatilization process and its properties
(Thesis (M.S.) - Robert College. Faculty of Graduate School of Engineering, 1969., 1969.) Kohen, Marko.; Noyan, Turgut.
Production of citric acid from Turkish molasses by fermentation
(Thesis (M.S.) - Robert College. Faculty of Graduate School of Engineering, 1969., 1969.) Mutluay, Işın.; Noyan, Turgut.
Protein by micro-organisms
(Thesis (M.S.) - Robert College. Faculty of Graduate School of Engineering, 199., 1969.) Özgen, Cenk.; Noyan, Turgut.
A study of penetration of oil into sorbents
(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1982., 1982.) Orhan, Metin.; Dinçer, Salih.; Tekeli, Sahim.
This study was initiated to absorb petroleum spills in sea waters. For this purpose, polyurethane and polypropylene were used as sorbents, and SAE 20W-20 motor oil and SAE 90W gear oil were used as oils. To observe the penetration of oils into sorbents, four groups of experiments were carried out the horizontal penetration of oils into dry polyurethanes, the horizontal displacement of water from polyurethanes (pre-wetted with water) by oil, the vertical penetration of oils into drypolypropylenes, and the vertical retention of oils by polyurethanes (pre-wetted with oil). Sorbents are characterized by their porosities, thicknesses, and fiber diameters. Such properties of .the sorbents used were obtained from the literature. The important properties of an oil are the density, the viscosity and the surface tension coefficient. The values for the density and the viscosity of oils used were supplied by Mobil Oil Company in Istanbul. The surface tension coefficients of these oilS also were measured in Bogaziçi University Labs. The sorbent/oil contact angle, which is another important parameter, was taken as zero by assuming that the sorbents were completely wetted with oil. A linear model, developed in literature for the horizontal penetration of oils into sorbents, was used in this study, and the experimental results obtained in this study did not agree with this model. Here, the distance penetrated by oil into sorbents was observed to be directly proportional to the square root of time. In addition, the horizontal displacement of water from sorbents by oil was also studied here. The polyurethane samples (pre-wetted with water) did not absorb oil, that is, water prevented the penetration of oil into Sorbent. Therefore, the displacement of water from sorbents by oil could not be achieved. This indicates that the sorbents can absorb oil from the surface of sea waters, if they are prevented from being wetted. The verticalpenetratjon rate model, taken from the literature, is nonlinear. The vertical retention model, which was·developed in this study, is also nonlinear. The experimental and the theoretical results showed that both the vertical penetration rate and the vertical retention were nonlinear. In the vertical penetration rate experiments, the rate at which oil climbed up the soroont was measured. In the vertical retention experiments, the rate at which oil drained from the sorbent was measured. The evalua.tions were based on these measurements.
Phase transition in homogeneous flow of nematic fluids
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Bahar, İvet.; Erman, Burak.; Dinçer, Salih.
Possibility of fonnation of a highly concentrated anisotropic phase in a dilute soluticn of rodlike molecules is investigated. The free energy expression for quiescent solutions of rodlike particles, introduced by Flory, is extended to the case where the molecules are subject to homogeneous velocity field. An additional term accounting for the contribution of the flow field to phase transition is incorporated into the free energy expression. The contribution of stressinduced diffusion is considered too. It is concluded that there will be a highly concentrated liquid crystalline phase deposition on the stagnant regions of the conduit, provided that the solvent-solute interaction is sufficiently high. The application of the theory to the aggregation of cholesterol molecules, in blood vessels, is discussed.
Extraction of lignites from Çan, Soma and Tunçbilek with donor and non-donor solvents in soxhlet extractor and autoclave
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1983., 1983.) Bolat, Esen.; Dinçer, Salih.
Available energy analysis of a petroleum refinery
(Thesis (M.S.)- Bogazici University. Institute for Graduate Studies in Science and Engineering, 1984., 1984.) Erkan, Deniz.; Dinçer, Salih.
The aim of this thesis is to examine the concept of available energy (availability) as applied to a petroleum refinery. For this purpose two different parts of the refinery were investigated. The first part, namely the plant 5 of İPRAŞ Refinery, deals mainly with separation and heat transfer processes. The second part, namely the Plant 6 of İPRAŞ Refinery, deals mainly with chemical reaction processes. The data needed in the calculation for Plant 5 were supplied by İPRAŞ. However, since Plant 6 involves chemical reactions and in chemically reacting systems standard chemical availabilities are needed and these standard chemical availabilities had to be simply estimated because of the uncertain structure of fractions. Therefore, the availability calculations carried out for Plant·6 are quite approximate and they are preliminary in nature. In addition, an availability analysis was made for each equipment of Plant 5 to investigate vlhere the availability losses occurred. The majority of process availability losses are in the furnaces, heat exchangers before desalters and in the air and water coolers. The availability loss of the overall process was also calculated for Plant 5 bv an overall balance. For·Plant 6, on the other hand, the availability calculations were made approximately only for the overall process .because of thelack of necessary data. In addition, an availability efficiency, which is also called Second Law efficiency in literature, was defined and it was reduced to suitable forms for different equipment.
Determination of thermophysical properties of polymer-solvent pairs by gas chromatography
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Öner, Mualla.; Dinçer, Salih.
In this study, thermophysical properties like Flory-Huggins interaction parameter ( X ), weight fraction infinite dilution activity coefficient (), heat of solution (Hs) and diffusion coefficient (D1) were determined for polyisobutylene (PIB), antishock polystyrene and styrene-butadiene rubber (SBR) with benzene, cyclohexane, n-hexane and n-pentane using gas chromatography (GC). The experiments were performed for antishock polystyrene at 313.3 to 402.3 K, for SBR at 343.3 to 363,2 K and for PIB at two different temperatures 312.1 K and 323.1 K • The chromatographic retention data obtained at these temperatures were used to determine the above mentioned thermophysica1 properties of polymer solvent pairs.
A process variable study of apple pectin extraction
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Dereboylu, E. Ayça.; Hortaçsu, Öner.; Arıcan, Haluk.
Dried Amasya apple pomace was used for extraction of apple pectin in this process variable study. Process variables of the extraction process were chosen as extraction temperature, duration of the extraction and acidity of the extraction medium. The effect of these variables on the yield and quality of pectin obtained were studied. To determine the quality of pectins their equivalent weights and methylester contents were measured. by titrating 0.5 per cent water solutions of pectins obtained with dilute alkali. Using the titration results total anhydrouronic acid contents of pectins were calculated. Absolute viscosities of one per cent water solutions of pectins obtained were measured. The results showed that pectin yield increased with time and temperature. It was seen that yield increase was directly related to the extraction time and the temperature effect was similar in all levels studied. The anhydrouronic acid content·of pectins increased with temperature. The methylester content of pectins- showed similar behaviour. as anhydrouronic acid content. The constant temperature lines crossed each other near 750 °C - 45 min point. At lower temperatures pectins with higher degree of esterification were obtained. The results showed also that pectin yield increased with increasing acidity. Anhydrouronic acid content was highest acidity and pectin with lower methylester content was obtained. Degree of esterification of pectins extracted increased with decreasing acidity of extraction medium. Experimehtal runs showed deviations from the literature as a result of the clqrification problem.
Gas chromatographic study of hydrogen and hydrocarbon adsorption on platinum/alumina catalyst
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Gönenç, Z. Sermin.; Önsan, Zeynep İlsen.
The irreversible and the reversible adsorption of hydrogen on commercial 0.3%wt Pt/Aı2O3 reforming catalyst has been studied in a gas-solid chromatograph in the temperature range 74-233 °C and 96-237 °C respectively. The reversible adsorption of two naphthenes (cyclohexane and methylcyclohexane) and of two aromatics (benzene and toluene) on the same catalyst have also been investigated between 190-236 °C. Adsorption isotherms were constructed at several temperatures for all the adsorbates studied. The elution (or the pulse) technique was used in all the experiments. From the adsorpti on isotherms heats of adsorption were calculated using constant surface coverage values at different temperatures. It was found that some hydrogen is adsorbed irreversibly within the temperature range considered and that the reversible adsorption of hydrogen is an activated process with an average heat of adsorption of 0.87 kcal/gmol (3.69 kj/kmol). The reversible adsorptions of cyclohexane, methylcyclohexane, benzene and toluene are also activated processes with average heats of adsoiption of 7.48 kcal/gmol (31.30 kJ/kmol), 7.45 kcal/gmol (31.17 kJ/kmo1), 13.11 kcal/gmol (54.85 kJ/kmol) and 13.90 kcal/gmol(58;16 kJ/kmol) respectively.
Determination of heat transfer coefficients in stirred tank systems
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Aksan, Devlet.; Önsan, Zeynep İlsen.; Borak, Fahir.
Heat transfer coefficients for helically coiled and continuously stirred tanks were determined using flat paddle turbine impellers. Heat transfer experiments have been carried out by varying the inlet temperature, flowrate of hot stream and agitator speed in the two flat bottom cylindrical stirred tanks in series. Experiments were also repeated for a single tank. The investigation was conducted under both steady-state and unsteady-state conditions with water being used, as the liquid to be mixed. The individual film heat transfer coefficients were calculated from the experimental overall heat transfer coefficients by using the Modified-Wilson Graphical Method. Two computer programs were also developed to check the validity of the analytical model used, and to compute film heat transfer coefficients and temperatures. A Reynolds number range of 19439 to 76727 was used for the agitated side, that there has been very little investigation in this region. In the coil side, the Reynolds number range was varied from 1100 to 14000. The convective heat transfer coefficients for unsteadystate conditions were found to have the same value as for steady-state conditions. The values of the individual film heat transfer coefficients found were in agreement with the previously published values for similar cases and the analytical model for heat transfer in two consecutive stirred tanks gave same results in agreement with the experimental results. Agitator speed was changed between 200 and 500 rpm. Higher values of heat transfer coefficients were observed with increasing agitator speeds.
Solution of the linearized equations of multicomponent mass transfer with chemical reaction by matrix methods
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Şentarlı, İnci.; Hortaçsu, Amable.
The linearized equations of multicomponent mass transfer with chemical reaction are solved by matrix methods fora film model. The molar flux of each component at the film boundary and the concentration profile of each component across the film are calculated. The general solution obtained is also applied to two variations. of the mass transfer problem; the case when there is no reaction and the case when there is reaction but no convection. The method of solution is applied to the cyclopropane-propene-argon-neon and the iodine-hydrogen-hydrogen iodideargon quaternary reacting sys·tems. The homogeneous reactions in both cases occur isothermally in the gas phase. The ·results of the computations show that as the reaction rates increase or as the diffusive fluxes decrease, the enhancement factors increase.The lower fluxes obtained in the cases when the convective terms are equated to zero snow thai the convective mechanism of mass transfer is just as important as the diffusive and reactive mechanisms in the film.
Mathematical modelling of a refinery furnace
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1985., 1985.) Burhanoğlu, Yüksel.; Borak, Fahir.
In this study, a mathematical model for the multiple fuel fired, Born type refinery furnace is derived in order to find temperature distribution in the furnace and vapor fraction of the charge. The model is solved by the numerical methods using computer programs written by the author. The model is available for steady-state. The necessary parameters such as air flowrate, molecular weight of flue gas, flue gas flowrate and adiabatic flame temperature which are not present in the data are calculated by material and energy balances. The furnace is analyzed in two sections with the assumption of one-dimensional heat transfer for gas and charge. The sections are defined according to the dominating heat transfer mechanism from the heat source, which are radiation and convection sections. Radiation section is further divided into three parts according to type of flow' of charge and location of tubes in which charge flows that are: (1) single phase flow in tubes on the walls, (2) two phase flow in tubes on the walls, (3) two phase flow in tubes at the ceiling of the radiation section. Both sections are divided into stages corresponding to each row of tubes. Temperature distribution in the furnace is found by making energy balances in each stage of each section. Vapor fraction of change at each stage is evaluated also by energy balances in two phase region. On the basis of modelling equations a computer program is developed for the furnace which uses an iterative procedure. Besides obtaining the numerical solutions of the model, the effect of change in input parameters on output conditions are also evaluated.
A finite element thermal hydraulic analysis of a plate type fuel element
(Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 1986., 1986.) Kazan, Ş. Nejat.; Borak, Fahir.; Hortaçsu, Öner.
In this work a mathematical model and a Computer program developed to perform thermcohydraulic analysis of a plate type fueled, water cooled nuclear core is presented. A finite element numerical solution was obtained for the two dimensional heat conduction model developed. For the transient case, the finite difference method was chosen to approximate the time derivative. In the early stages of this work a lot of time and effort were necessary for the preparation and entering of the needed data for calculations. This difficulty was overcome later after using a grid generating subroutine. In the determination of coolant temperature and pressure change mass, energy and momentum balance equations were evaluated for a control volume. The computer program NEKA developed, throughout this work is used for the steady state calculations. If desired, subcooled boiling and transient calculations can also be performed using NEKA. In all cases the program may be used either interactively or using data file. Two sample reactor cores were analyzed for various operating conditions such as the steady state analysis for a given power level, transient analysis with the change of power, coolant inflmi temperature, inflowing mass flowrate as a function of time. In the lMW power generating core, the Reactor I in Çekmece Nükleer Araştırma ve Eğitim Merkezi, showed to have a maximum fuel temperature of 76.7°C under normal operatingoxditkms for 37°C coolant input temperature This temperature reached to ,66.8 °C if coolant enters at 23 °C. In the transient analysis, for a given step change 90 per cent of the total change was observed to complete within 5.2 seconds. In the case of Reactor II which produces 5MW, the maximum fuel tanperature reached to 69.2°C under normal operating conditions for 30°C coolant input temperature. If the coolant flowrate is decreased to 0.065 kg/s from 0.31 kg/s or power level is increased to 17.5 MW subcoo1ed boiling occurance was predicted. For both reactors, the operating conditions were found to be safe.

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