Theses and Dissertations from UMD
Permanent URI for this communityhttp://hdl.handle.net/1903/2
New submissions to the thesis/dissertation collections are added automatically as they are received from the Graduate School. Currently, the Graduate School deposits all theses and dissertations from a given semester after the official graduation date. This means that there may be up to a 4 month delay in the appearance of a give thesis/dissertation in DRUM
More information is available at Theses and Dissertations at University of Maryland Libraries.
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Item ASSESSMENT OF PACKAGING MEDIA USED IN LONG-TERM STORAGE OF ELECTRONIC COMPONENTS(2021) Ravimanalan, Suraj; Das, Diganta; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Companies that produce end-products with long-term sustainment requirements undertake long-term storage as one of the measures to overcome the problem of electronic component obsolescence. To protect the components from environmental degradation during storage, they are packed inside vacuum sealed moisture barrier bags along with desiccants and humidity indicator cards. The desiccants have a specific adsorption capacity at a particular temperature / relative humidity condition. They cannot absorb the moisture permeated through the moisture barrier bag beyond that capacity. The relative humidity inside the moisture barrier bag also changes during long-term storage. This thesis provides a methodology to estimate the time to reach the desiccant's adsorption capacity and to estimate the increase in relative humidity inside the moisture barrier bag. The methodology is based on the experimental results and the first principle physical equations used for moisture permeation and adsorption. Based on these estimations, companies can decide on replacement schedules for moisture barrier bags and desiccants, thus protecting the electronic components contained within moisture barrier bags from humidity-related reliability issues.Item SIMULATION AND ANALYSIS OF ENERGY CONSUMPTION FOR TWO COMPLEX AND ENERGY-INTENSIVE BUILDINGS ON UMD CAMPUS(2017) Savage, Dana Mason; Ohadi, Michael M; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)The Microbiology Building and Hornbake Library are two multi-purpose and complex buildings, and are among the highest energy-intensive buildings on the University of Maryland College Park Campus. This thesis details the energy analysis and energy consumption models developed to identify energy savings opportunities for these two buildings. Three reports are given per building: one – a comprehensive summarization of relevant building information; two – a utility analysis, including an energy benchmarking study, evaluating the relative performance of each facility; three – a detailed energy model to replicate current operation and simulate potential energy savings resulting from no-and-low cost energy conservation measures. In total, 11 of the 12 measures simulated are strongly recommended for implementation. The predicted combined energy and utility savings are respectively 18,648.4 MMBtu and $436,128 annually. These actionable proposals to substantially reduce the buildings’ energy consumption contribute to the University’s commitment to achieve greater energy efficiency throughout campus.Item Design and Experimentation of a Manufacturable Solid Desiccant Wheel Assisted Separate Sensible and Latent Cooling Packaged Terminal Air Conditioning System(2014) Cristiano, Michael Vincent; Hwang, Yunho; Mechanical Engineering; Digital Repository at the University of Maryland; University of Maryland (College Park, Md.)Packaged terminal air conditioning (PTAC) systems are typically utilized for space heating and cooling in hotels and apartment buildings. However, in an effort to reach comfortable relative humidity in the conditioned space, they cool the air to its dew point and some reheating may be required to reach room set point temperature. In this study a commercial prototype of a solid desiccant wheel assisted separate sensible and latent cooling (SSLC) packaged terminal air conditioning (PTAC) system was designed . This iteration of the SSLC prototype was modeled based on PTAC type air conditioning units and was designed to achieve a 30% increase in system efficiency over current commercially available PTAC units. Heat exchangers used as evaporator and condenser were modeled in Coildesigner and VapCyc was used for system level modeling. Also a test facility was constructed in order to evaluate the performance of the proposed SSLC unit. Shakedown testing was conducted under various operating conditions in order to compare the SSLC system to a standard PTAC unit without desiccant wheel. With the necessary adjustments to the experimental prototype, the system could increase the overall capacity through latent cooling with negligible additional power consumption.