Slush is a two phase flow of solid particles (crystals) and liquid at the triple point temperature, and constitutes an appealing alternative to liquid propellants for space launchers. The crystals give to the mixture higher density and lower specific enthalpy than liquid, enabling reduced tank volume storage and larger fuel holding time. However, the presence of solid crystals significantly modifies the thermo-hydraulics of the fuel transport, and requires novel predictive tools and diagnostic techniques for efficiently exploiting slush propellants. This thesis contributes to both aspects. In particular, this work studied the flow pressure losses and the heat transfer of solid-liquid mixtures in pipelines, combining experimental and numerical methods. Hydraulic and thermal flow features were analyzed separately with substitute mixtures chosen to mimic the behavior of slush flows in engine fuel feed systems. A dedicated facility was designed and built. The pipeline mounted conventional probes for pressure, temperature and mass flow rate measurements. Moreover, a capacitance-based density meter was developed and validated to measure the mixture's solid content. Optical flow visualization and image processing routines were combined to retrieve particulate phase distribution and velocity fields. The experimental work was complemented with 3D Unsteady Reynolds Averaged Navier Stokes simulations in OpenFOAM. The simulations coupled the Euler-Euler approach with the granular kinetic theory for the treatment of the solid dispersed phase. The model was validated with the experimental results on the pressure drop, heat transfer and solid volume fraction.The resulting physical insights and the proposed empirical correlations on the pressure drop and heat transfer in solid-liquid flows contribute to move a step forward towards slush propelled space launchers. / Doctorat en Sciences de l'ingénieur et technologie / info:eu-repo/semantics/nonPublished

The master's thesis is devoted to the comparison of different types of lithium-ion batteries. Primarily, an introduction to electrochemical power sources and their division is described. Furthermore, the thesis deals only with lithium-ion batteries. In the theoretical part, the chapters discuss the history, the principle of operation and a detailed description of the main battery parts, including used materials. A comparison of commercially available lithium-ion cells with each other as well as with other types of batteries is also included in the theoretical part. The practical part deals with the cyclinf of lithium-ion cells and subsequent evaluation of the effect of temperature on the capacitance and current characteristics of these lithium-ion batteries.

This master’s thesis is focused on evaluation of standard uncertanities of measurement by method GUM and Monte Carlo and theirs comparation. In first part of this thesis is made the theoretical analysis of evaluation of measurement uncertanities and proposal of methodology for evaluating uncertainties by Monte Carlo method. In the second part is described direct and indirect measuring of resistance, capacitance and inductance, including evaluation of standard uncertanities of those measurings by GUM and Monte Carlo methods. In the end of this thesis is made comparison of achieved results of spoken methods.

We present oxide bipolar heterojunction diodes consisting of p-type ZnCo2O4 and n-type ZnO fabricated by pulsed-laser deposition. Hole conduction of ZnCo2O4 (ZCO) was evaluated by Hall and Seebeck effect as well as scanning capacitance spectroscopy. Both, ZCO/ZnO and ZnO/ZCO type heterostructures, showed diode characteristics. For amorphous ZCO deposited at room temperature on epitaxial ZnO/Al2O3 thin films, we achieved current rectification ratios up to 2x1010, ideality factors around 2, and long-term stability.

Indiana University-Purdue University Indianapolis (IUPUI) / The Electrical capacitance tomography (ECT) method has recently been adapted to obtain tomographic images of the cross section of a diesel particulate filter (DPF). However, a soot mass estimation algorithm is still needed to translate the ECT image pixel data to obtain soot load in the DPF. In this research, we propose an estimation method to quantify the soot load in a DPF through an inverse algorithm that uses the ECT images commonly generated by a back-projection algorithm. The grayscale pixel data generated from ECT is used in a matrix equation to estimate the permittivity distribution of the cross section of the DPF. Since these permittivity data has direct correlation with the soot mass present inside the DPF, a permittivity to soot mass distribution relationship is established first. A numerical estimation algorithm is then developed to compute the soot mass accounting for the mass distribution across the cross-section of the DPF as well as the dimension of the DPF along the exhaust flow direction. Firstly, ANSYS Electronic Desktop software is used to compute the capacitance matrix for different amounts of soot filled in the DPF, furthermore it also analyzed different soot distribution types applied to the DPF. The Analysis helped in constructing the sensitivity matrix which was used in the numerical estimation algorithm. Experimental data have been further used to verify the proposed soot estimation algorithm which compares the estimated values with the actual measured soot mass to validate the performance of the proposed algorithm.

京都大学 / 0048 / 新制・課程博士 / 博士(工学) / 甲第19185号 / 工博第4062号 / 新制||工||1627(附属図書館) / 32177 / 京都大学大学院工学研究科航空宇宙工学専攻 / (主査)教授 斧 髙一, 教授 木村 健二, 教授 立花 明知 / 学位規則第4条第1項該当 / Doctor of Philosophy (Engineering) / Kyoto University / DFAM

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Capacitive deionization based on electrosorption has become a viable process for brackish water desalination. In this study, activated biochar was employed as low-cost and alternative carbon-based electrodes substituting activated carbon with comparable adsorption capacity. Effects of different activation temperatures of the biochar were studied by physical characterization (i.e. SEM, TEM, elemental analysis, and Raman spectroscopy) and electrochemical characterization (i.e. cyclic voltammetry and galvanostatic charge/discharge measurement) based on the electrical double layer theory. The highest specific capacitance obtained (118.50 F g-1) was from activated biochar electrode treated at 800°C. The removal capacity was investigated by AAS and conductivity measurements. Several limitations associated with them were identified to improve the measurements. The removal capacity of biochar electrode is ~ 2 mg g-1 with significant results for both one-sided and two-sided t-test. In summary, activated biochar can be used as a cheap-alternative electrode material for desalination based on capacitive deionization.

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