This diploma thesis deals with the design of thermodynamic heat pump, used to utilize thermal energy of flue gases arised from the combustion of natural gas in a heat exchanger. The flow rates of the compader compressor, bypass compressor and turbine are calculated. Part of this thesis is simplified design of gearbox and economical evaluation of heat pump installation. The appendix of the thesis contains technical documentation.

The master thesis deals with design and comparison of condensing steam turbine for steam-gas cycle for single-cylinder and double-cylinder body with air condenser at its end, one regulated take and ability to use additive steam. Thesis is based on the calculation of thermal scheme which is followed by a preliminary and subsequently a detailed design of steam turbine. Thermodynamic efficiency for single-cylinder turbine was calculated at 93,28 % with terminal power 136,2 MW. The design procedure was repeated for a double-cylinder body. Calculated terminal power for two-cylinder turbine was 134,4 MW with thermodynamic efficiency of 92.1%. By dividing turbine into two rotors resulting low-pressure turbine has a smaller rotor diameter, a longer blade and at the same time a larger number of stages. For double-cylinder turbine, it was necessary to consider twice the number of seals and radial bearings. Due to the increase in flow diameter of low-pressure turbine, losses related to the geometry of the stage increased. Thesis is supplemented by a section drawing of steam turbine with higher efficiency.

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No description available.

Ignition delay time, τ_ign, is a key quantity of interest that is used to assess the predictability of a chemical kinetic model. This dissertation explores the sensitivity of τ_ign to uncertainties in: 1. rate-rule kinetic rates parameters and 2. enthalpies and entropies of fuel and fuel radicals using global and local sensitivity approaches. We begin by considering variability in τ_ign to uncertainty in rate parameters. We consider a 30-dimensional stochastic germ in which each random variable is associated with one reaction class, and build a surrogate model for τ_ign using polynomial chaos expansions. The adaptive pseudo-spectral projection technique is used for this purpose. First-order and total-order sensitivity indices characterizing the dependence of τ_ign on uncertain inputs are estimated. Results indicate that τ_ign is mostly sensitive to variations in four dominant reaction classes. Next, we develop a thermodynamic class approach to study variability in τ_ign of n-butanol due to uncertainty in thermodynamic properties of species of interest, and to define associated uncertainty ranges. A global sensitivity analysis is performed, again using surrogates constructed using an adaptive pseudo-spectral method. Results indicate that the variability of τ_ign is dominated by uncertainties in the classes associated with peroxy and hydroperoxide radicals. We also perform a combined sensitivity analysis of uncertainty in kinetic rates and thermodynamic properties which revealed that uncertainties in thermodynamic properties can induce variabilities in ignition delay time that are as large as those associated with kinetic rate uncertainties. In the last part, we develop a tangent linear approximation (TLA) to estimate the sensitivity of τ_ign with respect to individual rate parameters and thermodynamic properties in detailed chemical mechanisms. Attention is focused on a gas mixture reacting under adiabatic, constant-volume conditions. The proposed approach is based on integrating the linearized system of equations governing the evolution of the partial derivatives of the state vector with respect to individual random variables, and a linearized approximation is developed to relate ignition delay sensitivity to scaled partial derivatives of temperature. The computations indicate that TLA leads to robust local sensitivity predictions at a computational cost that is order-of-magnitude smaller than that incurred by finite-difference approaches.

The current understanding of the mechanical properties and deformation behavior of some individual phases in titanium alloys is limited due to the fine scale at which these phases precipitate within the β-phase matrix. The α and ω phases represent the most widely observed phases in titanium alloys depending on the alloy composition and also the heat treatment procedure adopted during processing. The possibility of precipitating ω-phase depends on the content of the β-stabilizers within the system. Although a significant compositional partitioning occurs within ω-phase upon aging treatment, the knowledge of ω-phase mechanical properties as a function of composition is very limited. The initial part of the current work focuses on the effect of common β-stabilizers elements on the phase stability and mechanical properties of the ω-phase using first-principles calculations. A relation between the bonding nature, the phase stability, and elastic properties was proposed. Thereafter αʺ martensitic phase was investigated in Ti-Nb and Ti-Nb-O alloys. The phase stability and martensitic start temperature of αʺ-phase was studied as a function of Nb and oxygen content. Also, the effect of the lattice shear distortion induced by oxygen atom on stabilizing β-phase was investigated. Subsequently the effect of the β-stabilizers' elements on stacking faults energy and ductility in α-Ti alloys was studied. Both prismatic and basal slip system were investigated with different concentration of β-stabilizers at the slip plane. Lastly, while the Tadmor and Bernstein model was employed to predict the partial dislocation emission and twinning propensity, the Rice criterion was used to estimate the effect of different β-stabilizers on the ductility of α-Ti alloys.

京都大学 / 0048 / 新制・課程博士 / 博士(農学) / 甲第19020号 / 農博第2098号 / 新制||農||1030(附属図書館) / 学位論文||H27||N4902(農学部図書室) / 31971 / 京都大学大学院農学研究科応用生命科学専攻 / (主査)教授 加納 健司, 教授 宮川 恒, 教授 三上 文三 / 学位規則第4条第1項該当 / Doctor of Agricultural Science / Kyoto University / DFAM

We present the results of a molecular simulation study of fluid mixtures, where complex diffusion behavior has experimentally been found and offer an explanation based on the hydrodynamic and thermodynamic components of the Fick diffusion coefficient. Special attention is paid to mixtures near critical and demixing regions, where in many cases strong discrepancies between different measurements of the Fick diffusion coefficients are found. Also molecular simulations are challenging in these regions and require extensive sampling due the presence of pronounced density fluctuations.

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Methyl Viologen (MV) is an electron mediator that has great possibilities to be used with an electrode system in which the electrode system provides electrons towards reducing MV species. MV has three redox states and they can be converted to each other via redox reactions on the surface of the electrode. The concentration of the three species of MV was related to the voltage potential applied to the system through a thermodynamic model. With the thermodynamic model the concentration of the three species can be predicted with different applied voltage potentials towards providing guidance for controlling the redox state of MV in a system. The kinetic rates of MV reduction were also assessed using a preliminary kinetic model. The kinetic model predicted all three species concentration changes with time although only the MV+ concentration was measured with time. Analysis revealed that the rate of MV reduction was three orders of magnitude slower than the rate of electrons required for bioethanol production. However, increasing the affinity of MV+ on the surface and blocking the H+ on the surface potentially can increase the reduction rate of MV by up to three orders of magnitude and can potentially enable MV to be used in commercial applications. As for the efficiency study, the coloumbic efficiency was less than 22% which was much lower than the efficiency of more than 85% observed in other studies for the direct electron transfer between electrode and bio organism. The efficiency was lowered mainly by the reduction of H+ and minimizing H+ on the electrode can largely increase the efficiency. Medium used for cell growth can also affect the efficiency through medium species consuming electrons provided by the electrode. Electron mediators, such as MV, have potential promise in applications such as microbial fuel cells, biofuel formation, and waste water treatment. However, engineering analysis of electron mediators is critical to provide better engineering control, design, and economic analysis for future applications.