No description available.

With the desire for conventional coal-fired power plants to perform flexible operations, the impact of this operation has become important to the field of steam turbine modelling. This study sought to develop a computationally inexpensive turbine model with minimal OEM intervention in order to predict the internal clearances of high-pressure and intermediate-pressure turbines from Eskom's current turbine fleet. The study saw the utilisation of the Nozzle Analogy theory to develop a 1D multistage turbine thermofluid model as well as the development of a representative 1D turbine process model in order to predict the internal temperature gradients promoted within a steam turbine during transient operation. From this model a further 3D FEA turbine model of both the HP and IP turbine units were developed from simple turbine diagrams to apply the predicted temperature boundaries and predict the thermal and structural response of turbine components during transient loading during a full Cold Start procedure. The result of this study was the successful validation of the 1D and 3D Turbine models against plant data from the candidate unit. This was in the form of known process data of unit performance, as well as thermocouple and differential expansion data taken from sensors housed on the turbine unit itself. Through the validation of these parameters, various calibrations techniques were developed over the course of the study with these techniques allowing investigators to gain insight into turbine aging, operator intervention as well as brought turbine component response. The successful establishment of the paired turbine model allowed investigators to evaluate the cold clearances defined during construction and maintenance of these turbine units in industry, which contributes greatly to the availability and efficiency of the unit during these transient operations. Additionally, the establishment of this model allowed for the investigation of the role that start up speed has on turbine component response. This study demonstrated that the development of such a modelling methodology was possible and yielded results with were accurate and insightful in understanding turbine component responses which are otherwise impossible to measure during real-world operation.

This report has been written to analyze a newly acquired measurement method within the companyAston Harald Mekaniska Verkstad AB, which is a 3D scanner made by the company Creaform. Thismodel bought has the name Metrascan 3D Black Elite. 3D scanning is an optical measurement methodwhich uses light to create a mesh of a measured object, where it is later compared to a nominal CAD filein the software Polyworks Inspector. To verify this method of measurement, it will be compared to twoother known calibrated and verified methods, which are coordinate measuring machines (CMM) andregular measuring instruments, which includes several kinds of micrometers and general anglemeasuring devices. To analyze and compare these methods an amount of data will be collected, and willbe used to conduct statistical analysis, where the mean/median, normal distribution, standarddeviation, and confidence intervals are included. The report will analyze two different kinds of data,where the first set consists of regular geometries such as linear and circular measurements, as well asseveral kinds of GD&T (Geometric Dimensions and Tolerances). The second set involves more complexgeometries according to the ISO standard ISO 484. The first set of data will be analyzed using amanufactured reference object, made using the aluminum alloy AL-7020 T6. The second set will beanalyzed using a propeller blade borrowed from the company Kongsberg. The results from this reportshow that 3D scanning is not as accurate nor as precise compared to CMM measurement and regularhand measuring instruments and cannot replace these measuring methods entirely. An empiricalformula has been derived from the analyzed data, and tolerance intervals are recommended to beincreased by approximately 0.1 to 1.0 % percent for regular linear and circular measurements dependingon the size of the detail measured. and upwards of 200 percent for GD&T tolerance intervals. However,3D scanning shows a greater promise when it comes to scanning propeller blades, as most measurementpoints were within specification according to the ISO 484 standard, and results can be further improved,such as with a tighter scanning mesh. Quality control and regulation is a topic whose discussion wasdesired, however, due to time constraints and the sensitivity of the scanner equipment, only an FMEAtable of potential error sources has been made for this report. Ergonomically some issues were found,particularly when it comes to static loading of arm muscles and repeated neck movement, both potentialsources for fatigue and injury. Recommended solutions for this include a flexible workstation whereboth the operator and the workpiece can be adjusted for optimal movement with minimal strain onpreviously mentioned body parts. Future improvements include performing a regression analysis ondifferent reference objects with many similar measurement types, for instance 50 holes with differentdiameters, which can lead to direct comparison formulas compared to nominal values. Furthermore,tests can be repeated with eliminating fault sources such as bad lightning.

No description available.

No description available.

No description available.

No description available.

Thermal expansion can be an issue in solid busbars, the expansion is caused by several factors and can cause plastic deformation in connection points or structure around it. The expansion occurs due to temperature differences in the busbar as a result of altered ambient temperature and/or joule heating. The environment where a vehicle is used can be harsh and varying in temperatures a lot. For future fast charging systems, a high amount of current will be passed in the conductors. In a stationary installation, this could be solved by increasing the cross-section area. In vehicles, the weight, cost, and space limitations callfor optimization of the conductor. In this thesis, there are several geometrical alterations done to the busbar to investigate the possibility to reduce the amount of stress acting on the connection points. The main geometrical evaluation is to compare a straight busbar to a U-shaped busbar. In the U-shape, the height, bend radius, and cross-section shape are investigated. To investigate this issue a simulation model was developed using Comsol, this software was used to evaluate stress values, max temperature, losses, and displacement. The results from the simulation showed that the U-shape has a large potential to reduce the amount of stress. Also, the cross-section shape tests showed that the steady-state temperature was lower for the more flatter shaped busbar. This is true both for the U-shape and straight busbar. This resulted inreduced amount of thermal expansion causing lower amount of stress, without adding any weight. The weight parameter is extremely important for vehicle implementation. The last test is looking at the busbar material where nickel-plated copper is compared to anodized aluminum. This test is divided into two parts, the first one is looking at an aluminum busbar compared to a copper busbar of the same geometry. This test showed that the losses in the aluminum busbar were much higher, but the steady-state temperature and max stress were lower. The second part of the test investigated the compensated aluminum busbar, this one is modeled by compensating the cross-section area for the higher resistance value of aluminum. The results from this busbar compared to the standard-shaped busbar showed a substantially lower stress, temperature and weight. But the overall dimensions are larger due to the compensated cross-section area. Having this larger Cross section area might hinder the implementation of aluminium busbars in parts of the vehicle where there is a lack of space, like in a battery box. / Termisk expansion i solida busbars är ett vanligt problem vid kraftig temperaturvariation. Problemet ökar med längden av busbaren och kan leda till plastisk deformation i infästningen av busbaren. Temperaturvariationen kan ske genom varierad omgivningstemperatur eller genom resistiv uppvärmning. Om en busbar ska användas i ett fordon för kraftöverföring är arbetsmiljön mycket påfrestande. Den termiska uppvärmningen går normalt att motverka genom att öka tvärsnittsarean, men i ett fordon där vikt, kostnad och platsbrist minskar möjligheten för ökad tvärsnittsarea blir optimering av ledaren extra viktig. För att undersöka problemet utvecklades en simuleringsmodell med hjälp av Comsol. Denna programvara använder för att utvärdera spänningskoncentrationer, maxtemperatur, förluster och utböjningar i busbaren. För att undersöka eventuella lösningar togs det fram flera geometriska variationer till busbaren, där möjligheten att använda en “U-form” utgjorde basen i en jämförelse mot en vanlig rakbusbar. För U-formen undersöktes U-höjden, böj-radien samt tvärsnittsformen. Även en jämförelse mellan nickelpläterad koppar och anodiserad aluminiumgenomfördes för att urskilja eventuella för och nackdelar med materialen. Resultaten från simuleringarna visade att U-formen gav klart lägre spänning i kontaktpunkterna. Även tvärsnittsformen påverkade temperaturen och spänningen i busbaren, där den plattare varianten presterade bättre på alla parametrar som undersöktes i simuleringen. För utvärderingen av materialet utfördes två tester, det första testet jämför en busbar i aluminium mot en i koppar med exakt samma geometri, detta testvisade att temperaturen samt spänningen blir lägre i aluminiumvarianten, dock ökar förlusterna kraftigt då aluminium har högre resistans än koppar. I den andra testet användes en kompenserad aluminiumbusbar där tvärsnittsarean har ökats för att ge samma resistans som kopparvarianten. Denna busbar fick en mycket lägre sluttemperatur, spänning och vikt. Förlusterna blev detsamma. Den högre tvärsnittsarean ger dock en fysiskt större busbar.

The effect of thermal-cycling-induced microcracking in fiber-reinforced polymer matrix composites is studied. Specific attention is focused on microcrack density as a function of the number of thermal cycles, and the effect of microcracking on the dimensional stability of composite materials. Changes in laminate coefficient of thermal expansion (CTE) and laminate stiffness are of primary concern. Included in the study are materials containing four different Thornel fiber types: a PAN-based T50 fiber and three pitch-based fibers, P55, P75, and P120. The fiber stiffnesses range from 55 Msi to 120 Msi. The fiber CTE's range from -0.50x10⁻⁶/°F to -0.80x10⁻⁶/°F. Also included are three matrix types: Fiberite's 934 epoxy, Amoco's ERL1962 toughened epoxy, and YLA's RS3 cyanate ester. The lamination sequences of the materials considered include a cross-ply configuration, [0/90]2s, and two quasi-isotropic configurations, [0/+45/-45/90]s and [0/+45/90/-45]s. The layer thickness of the materials range from a nominal 0.001 in. to 0.005 in. In addition to the variety of materials considered, three different thermal cycling temperature ranges are considered. These temperature ranges are ±250°F, ±150°F, and ±50°F. The combination of these material and geometric parameters and temperature ranges, combined with thermal cycling to thousands of cycles, makes this one of the most comprehensive studies of thermal-cycling-induced microcracking to date. Experimental comparisons are presented by examining the effect of layer thickness, fiber type, matrix type, and thermal cycling temperature range on microcracking and its influence on the laminates. Results regarding layer thickness effects indicate that thin-layer laminates microcrack more severely than identical laminates with thick layers. For some specimens in this study, the number of microcracks in thin-layer specimens exceeds that in thick-layer specimens by more than a factor of two. Despite the higher number of microcracks in the thin-layer specimens, small changes in CTE after thousands of cycles indicate that the thin-layer specimens are relatively unaffected by the presence of these cracks compared to the thick-layer specimens. Results regarding fiber type indicate that the number of microcracks and the change in CTE after thousands of cycles in the specimens containing PAN-based fibers are less than in the specimens containing comparable stiffness pitch-based fibers. Results for specimens containing the different pitch-based fibers indicate that after thousands of cycles, the number of microcracks in the specimens does not depend on the modulus or CTE of the fiber. The change in laminate CTE does, however, depend highly on the stiffness and CTE of the fiber. Fibers with higher stiffness and more negative CTE exhibit the lowest change in laminate CTE as a result of thermal cycling. The overall CTE of these specimens is, however, more negative as a result of the more negative CTE of the fiber. Results regarding matrix type based on the ±250°F temperature range indicate that the RS3 cyanate ester resin system exhibits the greatest resistance to microcracking and the least change in CTE, particularly for cycles numbering 3000 and less. Extrapolations to higher numbers of cycles indicate, however, that the margin of increased performance is expected to decrease with additional thermal cycling. Results regarding thermal cycling temperature range depend on the matrix type considered and the layer thickness of the specimens. For the ERL1962 resin system, microcrack saturation is expected to occur in all specimens, regardless of the temperature range to which the specimens are exposed. By contrast, the RS3 resin system demonstrates a threshold effect such that cycled to less severe temperature ranges, microcracking does not occur. For the RS3 specimens with 0.005 in. layer thickness, no microcracking or changes in CTE are observed in specimens cycled between between ±150°F or ±50°F. For the RS3 specimens with 0.002 in. layer thickness, no microcracking or changes in CTE are observed in specimens cycled between ±50°F.. Results regarding laminate stiffness indicate negligible change in laminate stiffness due to thermal cycling for the materials and geometries considered in this investigation. The study includes X-ray examination of the specimens, showing that cracks observed at the edge of the specimens penetrate the entire width of the specimen. Glass transition temperatures of the specimens are measured, showing that resin chemistry is not altered as a result of thermal cycling. Results are also presented based on a one-dimensional shear lag analysis developed in the literature. The analysis requires material property information that is difficult to obtain experimentally. Using limited data from the present investigation, material properties associated with the analysis are modified to obtain reasonable agreement with measured microcrack densities. Based on these derived material properties, the analysis generally overpredicts the change in laminate CTE. Predicted changes in laminate stiffness show reasonable correlation with experimentally measured values. / Ph. D.

Steepest-entropy-ascent quantum thermodynamics (SEAQT) is a mathematical and theoretical framework for intrinsic quantum thermodynamics (IQT), a unified theory of quantum mechanics and thermodynamics. In the theoretical framework, entropy is viewed as a measure of energy load sharing among available energy eigenlevels, and a unique relaxation path of a system from an initial non-equilibrium state to a stable equilibrium is determined from the greatest entropy generation viewpoint. The SEAQT modeling has seen a great development recently. However, the applications have mainly focused on gas phases, where a simple energy eigenstructure (a set of energy eigenlevels) can be constructed from appropriate quantum models by assuming that gas-particles behave independently. The focus of this research is to extend the applicability to solid phases, where interactions between constituent particles play a definitive role in their properties so that an energy eigenstructure becomes quite complicated and intractable from quantum models. To cope with the problem, a highly simplified energy eigenstructure (so-called ``pseudo-eigenstructure") of a condensed matter is constructed using a reduced-order method, where quantum models are replaced by typical solid-state models. The details of the approach are given and the method is applied to make kinetic predictions in various solid-state phenomena: the thermal expansion of silver, the magnetization of iron, and the continuous/discontinuous phase separation and ordering in binary alloys where a pseudo-eigenstructure is constructed using atomic/spin coupled oscillators or a mean-field approximation. In each application, the reliability of the approach is confirmed and the time-evolution processes are tracked from different initial states under varying conditions (including interactions with a heat reservoir and external magnetic field) using the SEAQT equation of motion derived for each specific application. Specifically, the SEAQT framework with a pseudo-eigenstructure successfully predicts: (i) lattice relaxations in any temperature range while accounting explicitly for anharmonic effects, (ii) low-temperature spin relaxations with fundamental descriptions of non-equilibrium temperature and magnetic field strength, and (iii) continuous and discontinuous mechanisms as well as concurrent ordering and phase separation mechanisms during the decomposition of solid-solutions. / Ph. D. / Many engineering materials have physical and chemical properties that change with time. The tendency of materials to change is quantified by the field of thermodynamics. The first and second laws of thermodynamics establish conditions under which a material has no tendency to change; these conditions are called equilibrium states. When a material is not in an equilibrium state, it is able to change spontaneously. Classical thermodynamics reliably identifies whether a material is susceptible to change, but it is incapable of predicting how change will take place or how fast it will occur. These are kinetic questions that fall outside the purview of thermodynamics. A relatively new theoretical treatment developed by Hatsopoulos, Gyftopoulos, Beretta and others over the past forty years extends classical thermodynamics into the kinetic realm. This framework, called steepest-entropy-ascent quantum thermodynamics (SEAQT), combines the tools of thermodynamics with quantum mechanics through a postulated equation of motion. Solving the equation of motion provides a kinetic description of the path a material will take as it changes from a non-equilibrium state to stable equilibrium. To date, the SEAQT framework has been applied primarily to systems of gases. In this dissertation, solid-state models are employed to extend the SEAQT approach to solid materials. The SEAQT framework is used to predict the thermal expansion of silver, the magnetization of iron, and the kinetics of atomic clustering and ordering in binary solid-solutions as a function of time or temperature. The model makes it possible to predict a unique kinetic path from any arbitrary, non-equilibrium, initial state to a stable equilibrium state. In each application, the approach is tested against experimental data. In addition to reproducing the qualitative kinetic trends in the cases considered, the SEAQT framework shows promise for modeling the behavior of materials far from equilibrium.