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- All Subjects: energy
- Creators: Arizona State University
- Status: Published
Description
Dynamic loading is the term used for one way of optimally loading a transformer. Dynamic loading means the utility takes into account the thermal time constant of the transformer along with the cooling mode transitions, loading profile and ambient temperature when determining the time-varying loading capability of a transformer. Knowing the maximum dynamic loading rating can increase utilization of the transformer while not reducing life-expectancy, delaying the replacement of the transformer. This document presents the progress on the transformer dynamic loading project sponsored by Salt River Project (SRP). A software application which performs dynamic loading for substation distribution transformers with appropriate transformer thermal models is developed in this project. Two kinds of thermal hottest-spot temperature (HST) and top-oil temperature (TOT) models that will be used in the application--the ASU HST/TOT models and the ANSI models--are presented. Brief validations of the ASU models are presented, showing that the ASU models are accurate in simulating the thermal processes of the transformers. For this production grade application, both the ANSI and the ASU models are built and tested to select the most appropriate models to be used in the dynamic loading calculations. An existing application to build and select the TOT model was used as a starting point for the enhancements developed in this work. These enhancements include: Adding the ability to develop HST models to the existing application, Adding metrics to evaluate the models accuracy and selecting which model will be used in dynamic loading calculation Adding the capability to perform dynamic loading calculations, Production of a maximum dynamic load profile that the transformer can tolerate without acceleration of the insulation aging, Provide suitable output (plots and text) for the results of the dynamic loading calculation. Other challenges discussed include: modification to the input data format, data-quality control, cooling mode estimation. Efforts to overcome these challenges are discussed in this work.
ContributorsLiu, Yi (Author) / Tylavksy, Daniel J (Thesis advisor) / Karady, George G. (Committee member) / Ayyanar, Raja (Committee member) / Arizona State University (Publisher)
Created2011
Description
Emission of CO2 into the atmosphere has become an increasingly concerning issue as we progress into the 21st century Flue gas from coal-burning power plants accounts for 40% of all carbon dioxide emissions. The key to successful separation and sequestration is to separate CO2 directly from flue gas (10-15% CO2, 70% N2), which can range from a few hundred to as high as 1000°C. Conventional microporous membranes (carbons/silicas/zeolites) are capable of separating CO2 from N2 at low temperatures, but cannot achieve separation above 200°C. To overcome the limitations of microporous membranes, a novel ceramic-carbonate dual-phase membrane for high temperature CO2 separation was proposed. The membrane was synthesized from porous La0.6Sr0.4Co0.8Fe0.2O3-d (LSCF) supports and infiltrated with molten carbonate (Li2CO3/Na2CO3/K2CO3). The CO2 permeation mechanism involves a reaction between CO2 (gas phase) and O= (solid phase) to form CO3=, which is then transported through the molten carbonate (liquid phase) to achieve separation. The effects of membrane thickness, temperature and CO2 partial pressure were studied. Decreasing thickness from 3.0 to 0.375 mm led to higher fluxes at 900°C, ranging from 0.186 to 0.322 mL.min-1.cm-2 respectively. CO2 flux increased with temperature from 700 to 900°C. Activation energy for permeation was similar to that for oxygen ion conduction in LSCF. For partial pressures above 0.05 atm, the membrane exhibited a nearly constant flux. From these observations, it was determined that oxygen ion conductivity limits CO2 permeation and that the equilibrium oxygen vacancy concentration in LSCF is dependent on the partial pressure of CO2 in the gas phase. Finally, the dual-phase membrane was used as a membrane reactor. Separation at high temperatures can produce warm, highly concentrated streams of CO2 that could be used as a chemical feedstock for the synthesis of syngas (H2 + CO). Towards this, three different membrane reactor configurations were examined: 1) blank system, 2) LSCF catalyst and 3) 10% Ni/y-alumina catalyst. Performance increased in the order of blank system < LSCF catalyst < Ni/y-alumina catalyst. Favorable conditions for syngas production were high temperature (850°C), low sweep gas flow rate (10 mL.min-1) and high methane concentration (50%) using the Ni/y-alumina catalyst.
ContributorsAnderson, Matthew Brandon (Author) / Lin, Jerry (Thesis advisor) / Alford, Terry (Committee member) / Rege, Kaushal (Committee member) / Anderson, James (Committee member) / Rivera, Daniel (Committee member) / Arizona State University (Publisher)
Created2011
Description
La frontera entre México y Estados Unidos es un territorio que se ha conceptualizado y construido por el centralismo mexicano y por el discurso chicano dominante: el de Borderlands. Estos dos focos equidistantes establecen sus perspectivas a partir del contacto que la región fronteriza tiene con los Estados Unidos en términos de intercambios económicos y culturales. La tradición de definir la zona fronteriza se inicia a partir de 1848 con el Tratado de Guadalupe Hidalgo. Más tarde, dicha región estaría en indiferencia por su distancia geográfica con el centro mexicano, excepto durante la Revolución mexicana. Sin embargo, la región fronteriza empieza a recibir gran atención hacia finales del Siglo XX, cuando nuevas formas de intercambio económico entre México y Estados Unidos se empiezan a desarrollar. La frontera, entonces experimenta un crecimiento económico que se refleja, a su vez, en el resurgimiento y crecimiento de la cultura fronteriza. El antropólogo cultural, Nestor García Canclini intentó definir la cultura fronteriza al analizar el uso del idioma inglés en Tijuana. En sus estudios, tanto Tijuana: la casa de toda la gente (1989) como Culturas híbridas: Cómo entrar y salir de la modernidad (1992), García Canclini sostiene que la frontera es un espacio de hibridación cultural. Por otro lado, las teorías dominantes dentro del campo chicano definen la frontera en términos metafísicos. Para Gloria Anzaldúa, el espacio fronterizo es el Borderlands: un área geográfica en donde los paradigmas de la psicología del individuo están en constante conflicto. Considerando estos antecedentes como punto de partida, esta investigación se enfoca en el estudio de la cultura fronteriza como múltiples universos de signos que entran en contacto unos con otros. Tal como lo establece Iury Lotman en su estudio teórico La semiosfera (1996), una semiosfera es un espacio delimitado por una frontera que, a su vez, tiene la función de traducir información de otras semiosferas. De manera que dicho concepto se muestra adecuado para analizar El gran preténder (1992) de Luis Humberto Crosthwaite y Berlín 77 (y otros relatos) (2003) de Carlos Adolfo Gutiérrez Vidal. En última instancia, al establecer los espacios fronterizos como universos culturales (semiosferas) se devela el nivel de contacto entre éstas, especialmente entre las semiosferas mexicana/americana y la fronteriza.
ContributorsEncinas, Diana (Author) / Volek, Emil (Committee member) / Hernández-G., Manuel De Jesús (Committee member) / Acereda, Alberto (Committee member) / Arizona State University (Publisher)
Created2011
Description
This thesis pursues a method to deregulate the electric distribution system and provide support to distributed renewable generation. A locational marginal price is used to determine prices across a distribution network in real-time. The real-time pricing may provide benefits such as a reduced electricity bill, decreased peak demand, and lower emissions. This distribution locational marginal price (D-LMP) determines the cost of electricity at each node in the electrical network. The D-LMP is comprised of the cost of energy, cost of losses, and a renewable energy premium. The renewable premium is an adjustable function to compensate `green' distributed generation. A D-LMP is derived and formulated from the PJM model, as well as several alternative formulations. The logistics and infrastructure an implementation is briefly discussed. This study also takes advantage of the D-LMP real-time pricing to implement distributed storage technology. A storage schedule optimization is developed using linear programming. Day-ahead LMPs and historical load data are used to determine a predictive optimization. A test bed is created to represent a practical electric distribution system. Historical load, solar, and LMP data are used in the test bed to create a realistic environment. A power flow and tabulation of the D-LMPs was conducted for twelve test cases. The test cases included various penetrations of solar photovoltaics (PV), system networking, and the inclusion of storage technology. Tables of the D-LMPs and network voltages are presented in this work. The final costs are summed and the basic economics are examined. The use of a D-LMP can lower costs across a system when advanced technologies are used. Storage improves system costs, decreases losses, improves system load factor, and bolsters voltage. Solar energy provides many of these same attributes at lower penetrations, but high penetrations have a detrimental effect on the system. System networking also increases these positive effects. The D-LMP has a positive impact on residential customer cost, while greatly increasing the costs for the industrial sector. The D-LMP appears to have many positive impacts on the distribution system but proper cost allocation needs further development.
ContributorsKiefer, Brian Daniel (Author) / Heydt, Gerald T (Thesis advisor) / Shunk, Dan (Committee member) / Hedman, Kory (Committee member) / Arizona State University (Publisher)
Created2011
Description
A relatively simple subset of nanotechnology - nanofluids - can be obtained by adding nanoparticles to conventional base fluids. The promise of these fluids stems from the fact that relatively low particle loadings (typically <1% volume fractions) can significantly change the properties of the base fluid. This research explores how low volume fraction nanofluids, composed of common base-fluids, interact with light energy. Comparative experimentation and modeling reveals that absorbing light volumetrically (i.e. in the depth of the fluid) is fundamentally different from surface-based absorption. Depending on the particle material, size, shape, and volume fraction, a fluid can be changed from being mostly transparent to sunlight (in the case of water, alcohols, oils, and glycols) to being a very efficient volumetric absorber of sunlight. This research also visualizes, under high levels of irradiation, how nanofluids undergo interesting, localized phase change phenomena. For this, images were taken of bubble formation and boiling in aqueous nanofluids heated by a hot wire and by a laser. Infrared thermography was also used to quantify this phenomenon. Overall, though, this research reveals the possibility for novel solar collectors in which the working fluid directly absorbs light energy and undergoes phase change in a single step. Modeling results indicate that these improvements can increase a solar thermal receiver's efficiency by up to 10%.
ContributorsTaylor, Robert (Author) / Phelan, Patrick E (Thesis advisor) / Adrian, Ronald (Committee member) / Trimble, Steve (Committee member) / Posner, Jonathan (Committee member) / Maracas, George (Committee member) / Arizona State University (Publisher)
Created2011
Description
The electrode-electrolyte interface in electrochemical environments involves the understanding of complex processes relevant for all electrochemical applications. Some of these processes include electronic structure, charge storage, charge transfer, solvent dynamics and structure and surface adsorption. In order to engineer electrochemical systems, no matter the function, requires fundamental intuition of all the processes at the interface. The following work presents different systems in which the electrode-electrolyte interface is highly important. The first is a charge storage electrode utilizing percolation theory to develop an electrode architecture producing high capacities. This is followed by Zn deposition in an ionic liquid in which the deposition morphology is highly dependant on the charge transfer and surface adsorption at the interface. Electrode Architecture: A three-dimensional manganese oxide supercapacitor electrode architecture is synthesized by leveraging percolation theory to develop a hierarchically designed tri-continuous percolated network. The three percolated phases include a faradaically-active material, electrically conductive material and pore-former templated void space. The micropores create pathways for ionic conductivity, while the nanoscale electrically conducting phase provides both bulk conductivity and local electron transfer with the electrochemically active phase. Zn Electrodeposition: Zn redox in air and water stable N-ethyl-N-methylmorpholinium bis(trifluoromethanesulfonyl)imide, [C2nmm][NTf2] is presented. Under various conditions, characterization of overpotential, kinetics and diffusion of Zn species and morphological evolution as a function of overpotential and Zn concentration are analyzed. The surface stress evolution during Zn deposition is examined where grain size and texturing play significant rolls in compressive stress generation. Morphological repeatability in the ILs led to a novel study of purity in ionic liquids where it is found that surface adsorption of residual amine and chloride from the organic synthesis affect growth characteristics. The drivers of this work are to understand the processes occurring at the electrode-electrolyte interface and with that knowledge, engineer systems yielding optimal performance. With this in mind, the design of a bulk supercapacitor electrode architecture with excellent composite specific capacitances, as well as develop conditions producing ideal Zn deposition morphologies was completed.
ContributorsEngstrom, Erika (Author) / Friesen, Cody (Thesis advisor) / Buttry, Daniel (Committee member) / Sieradzki, Karl (Committee member) / Arizona State University (Publisher)
Created2011
Description
In the first thirty years of the XX century, an old literary visual tradition was reborn in a series of new striking visual texts better known as calligrams. They were produced by some avant-garde poets such as Vicente Huidobro, José Juan Tablada, Alberto Hidalgo and Carlos Oquendo de Amat in Latin America, and Juan Larrea, Guillermo de Torre, Francisco Vighi, Luis Mosquera, and others in Spain. However, with few exceptions, the interpretation of those written drawings has caught little attention from literary critics. This research, contrasted to that of Willard Bohn's, is a contribution to the deciphering of such literary art form, designated here as the figurative visual poem. It is a proposal for its visual reading which draws from the fact that this type of text is concretely a drawing formed by written verses. As such, it can be regarded as a plastic writing, combining pictorial and verbal signs in one perceptible configuration on the page. The result of this semiotic operation is a hybrid product in which the iconic forms become symbolic and vice versa. It is in fact, an art object which should be approached as a text that can be seen as well as read. The study leads to the conclusion that Willard Bohn misreads the order in which language and image are articulated in the visual poem identified with the second order semiological system proposed by Roland Barthes, placing preeminence on language over image. This results in reading the avant-garde visual figurative poem in an ekphrastic fashion. Consequently, the role of the image in the system is left in an ambiguous realm at the time of deciphering this hybrid text. Our contribution to re-conducting this undertaking has been equally drawn from a semiotic stance taken from Louis Hjemslev that balances language and image as correlates of a semiotic function. Due to the signaling nature of both, language and figure, a visual poem becomes an iconic metaphor as well as a metaphoric icon, and moreover a self-referential sign, thus justifying its status of an autonomous art.
ContributorsSuarez, Nelson M (Author) / Acereda, Alberto (Thesis advisor) / Volek, Emil (Committee member) / Garcia-Fernandez, Carlos J (Committee member) / Arizona State University (Publisher)
Created2011
Description
Antonio López de Santa Anna (1794-1876) is considered as one of the biggest villains of Mexican history. This frequent president in the first decades of Independence of México is the main character portrayed in the novels analyzed in this dissertation: Su alteza serenísima (1895-1896) by Ireneo Paz, Santa Anna, el dictador resplandeciente (1936) by Rafael F. Muñoz, El seductor de la patria (1999) by Enrique Serna, and México mutilado (2006) by Francisco Martín Moreno. Many Mexican novelists have tackled iconic personalities from Mexican history. However, based upon the historical context that occurred within their lifetime, each author takes a different approach to the story and characters they portray. In the novel Su alteza serenísima, Santa Anna is presented with identical characteristics as in the official history. That was written for other liberals, like Paz, the author. In El dictador resplandeciente an image almost romantic of the leader is presented through the valorization of his role in history. The narrator shows the contradictions of Santa Anna, who was a hero and villain. Santa Anna is presented from different perspectives in El seductor de la patria. The narrator uses Santa Anna's voice projecting a consciousness of the future's judgment of history upon his actions and the voices of "the others" that live around him. In México mutilado Santa Anna is presented from the same perspective as the official history, although other traitors are added to distribute the fault among various important figures. This dissertation works through the analysis of the discursive mechanisms used in these novels, of the configuration of the message that they wish to convey to the reader, of the level of re-writing official history, of the perspective from which each author is reviewing the history, of the recount of what historical aspects and voices were chosen for inclusion in each novel, and through the evaluation of how the authors recover the figure of Santa Anna. This study follows an eclectic model of cultural commentary, taking up critical concepts from Latin American literary scholars such as Perkowska, Pons, Jitrik, Aínsa, among others.
ContributorsSigüenza Ponce, Olga (Author) / Volek, Emil (Thesis advisor) / Acereda, Alberto (Committee member) / Hernández-Gutierrez, Manuel J (Committee member) / Arizona State University (Publisher)
Created2011
Description
In the midst of historical ruptures and transfiguration caused by a globalization that has restructured new realities marked by violence, Central American and Chicanos realities have come into contact in a global space such the United States. Thus, the interdependence between these two cultures is so close that the literary influences are unavoidable. We argue that there is an asymmetrical relationship in the narrative of globalization, which sets new unpublished orders and generates perceptions of reality. The ideological dimensions of globalization that have caused systemic violence can be traced through military interventions and economic ventures. Thus, the subject of our research is assumed as a literary whole within certain social facts, i.e., as a symbolic aspect of the processes of violence within a culture undermined by globalization. Hence, in using theory of violence by Slavoj Ziek and theory of globalization by Manuel Castells, Tony Shirato, Jenn Webb, James Petra, and Henry Veltmeyer, we explore the narrative and criticism of U.S-Central Americans and Chicano in order to expose the forces of systemic violence that globalization produces. Our results show that, historically, globalization has formulated epistemologies via violence for Chicanos and U.S-Central Americans; such violence marks both groups, allowing for solidarity, through discursive practices of resistance, to take place in the textual space as well as in the real world. Such solidarity disrupts the textual borders, creating a dialogue of mutual understanding.
ContributorsEscobar, Mario A (Author) / Hernández-G, Manuel De Jesús (Thesis advisor) / Rosales, Jesus (Thesis advisor) / Menjivar, Cecilia (Committee member) / Arizona State University (Publisher)
Created2011
Description
In this thesis the performance of a Hybrid AC System (HACS) is modeled and optimized. The HACS utilizes solar photovoltaic (PV) panels to help reduce the demand from the utility during peak hours. The system also includes an ice Thermal Energy Storage (TES) tank to accumulate cooling energy during off-peak hours. The AC runs continuously on grid power during off-peak hours to generate cooling for the house and to store thermal energy in the TES. During peak hours, the AC runs on the power supplied from the PV, and cools the house along with the energy stored in the TES. A higher initial cost is expected due to the additional components of the HACS (PV and TES), but a lower operational cost due to higher energy efficiency, energy storage and renewable energy utilization. A house cooled by the HACS will require a smaller size AC unit (about 48% less in the rated capacity), compared to a conventional AC system. To compare the cost effectiveness of the HACS with a regular AC system, time-of-use (TOU) utility rates are considered, as well as the cost of the system components and the annual maintenance. The model shows that the HACS pays back its initial cost of $28k in about 6 years with an 8% APR, and saves about $45k in total cost when compared to a regular AC system that cools the same house for the same period of 6 years.
ContributorsJubran, Sadiq (Author) / Phelan, Patrick (Thesis advisor) / Calhoun, Ronald (Committee member) / Trimble, Steve (Committee member) / Arizona State University (Publisher)
Created2011