Global energy demands are on the rise, and the current technology used to generate, transmit, and distribute electricity will not be able to meet the growth due to the bottlenecks in densely populated areas and the inefficiencies throughout the electrical grid. Soon, new technologies will be required to relieve the constraints on the grid while being cost effective, reliable, and environmentally acceptable. High temperature superconducting (HTS) technology being developed has the means to provide ways to overcome the challenges faced by electric utility companies. Other applications including all-electric ships and aircrafts would also benefit greatly from the use of HTS power devices in meeting the increasing electrical power requirements at high power densities. HTS power technology is relatively complex, and it involves multiple technological and scientific disciplines besides the materials being expensive currently to enable cost-effective applications. Therefore, intensive numerical modeling efforts are necessary to improve the designs and system level optimizations so that the technology will be commercially viable. The goal of the research described here is to investigate and develop effective methods of modeling and simulating HTS power devices cooled with gaseous helium (GHe) circulation. The technique of GHe-cooled HTS power systems is relatively new, and there is much room for improvements in designs, particularly integrating the superconducting and cryogenics systems. Benefits of modeling the systems in detail include reduced cost and time and the ability to perform optimizations; each of which would allow faster development cycles at lower cost. These benefits arise from the fact that it’s more efficient to design complex systems using bits as opposed to atoms. A 30-m long HTS power cable including the cable terminations and the cryogenic helium circulation system is the primary system studied in this work. GHe offers some important benefits over liquid nitrogen including improved safety in confined spaces and lower operating temperatures especially for superconducting applications that require high power densities such as those to be used on all-electric Navy ships. However, there are still some challenges that need to be addressed. GHe possesses lower heat capacity per unit volume compared to liquid cryogens, and its weak dielectric strength currently restricts its use in HTS power cables at low and medium voltage applications. This dissertation describes numerical modeling techniques including volume element methods and finite element methods that were developed to visualize the physics of several different HTS cable system components. The modelling techniques developed were further utilized for transient analysis of the cryogenic thermal and electrical behavior under various scenarios and system operational contingencies to assess the limitations of the technology and to devise methods for mitigating the contingencies. / A Dissertation submitted to the Department of Mechanical Engineering in partial fulfillment of the Doctor of Philosophy. / Summer Semester 2017. / July 20, 2017. / cryogenics, helium gas, numerical modeling, superconductivity / Includes bibliographical references. / Juan Ordonez, Professor Co-Directing Dissertation; Sastry Pamidi, Professor Co-Directing Dissertation; Hui "Helen" Li, University Representative; Wei Guo, Committee Member; Patrick Hollis, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_552138 |
| Contributors | Suttell, Nicholas George (authoraut), Ordóñez, Juan Carlos, 1973- (professor co-directing dissertation), Pamidi, Sastry V. (professor co-directing dissertation), Li, Hui, 1970- (university representative), Guo, Wei (Professor of Mechanical Engineering) (committee member), Hollis, Patrick J. (committee member), Florida State University (degree granting institution), FAMU-FSU College of Engineering (degree granting college), Department of Mechanical Engineering (degree granting departmentdgg) |
| Publisher | Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text, doctoral thesis |
| Format | 1 online resource (105 pages), computer, application/pdf |
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