Doctor of Philosophy (Ph.D.), University of Dayton, 2022, Mechanical Engineering

This work further investigates a novel concentrating solar thermal desalination process using a dual tank system, which addresses one of the biggest challenges in wider adoption of solar applications: 24-hr dispatching of solar energy. Direct use of solar energy only during daily sun hours might be acceptable on a small scale, but not economically viable on a larger scale. In this study, a complete once through multi-stage flash (MSF-OT) desalination plant powered by solar thermal energy was modeled using the TRNSYS modeling environment. The model results are in good agreement with previous general studies, but the novelty here is development and use of a component-based, dynamic simulation model of the entire desalination plant, which more accurately represents real situations, and allows parametric analyses of important design variables such as the number of stages, top brine temperature, operating pressures, and solar concentrator area. System improvements relative to previous studies included use of series/parallel configuration of the solar concentrator array, and improved thermodynamic modeling of vacuum pressures in flashing tanks, and the addition of a heat recovery section for brine preheating. As a result, the size of the solar concentrator array can be reduced by 54% relative to previous studies, and based on a detailed economic analysis, the water price can be reduced by nearly 15% to $ 2.33/m3 .

Committee: Andrew Chiasson (Advisor); Kevin Hallinan (Committee Member); Rydge Mulford (Committee Member); Muhammad Usman (Committee Member) Subjects: Condensation; Energy; Engineering; Mechanical Engineering; Systems Design; Water Resource Management

Master of Science in Mechanical Engineering, Cleveland State University, 2022, Washkewicz College of Engineering

Water main geothermal systems have the potential to bring geothermal heat pump systems to a larger scale and drastically reduce carbon emissions. Current research supports this by showing that the quality of water produced by these systems remains unchanged (Smith and Liu 2018). There have been studies that show some form of economic feasibility without an in-depth design, evaluation, and economic analysis (Ambort and Farrell 2020). This research will provide that analysis and help determine any next steps to achieve the feasibility of the design and implementation of these systems on a larger scale and the impact these systems will have on reducing carbon emissions. The main objective of this research is to design, evaluate, and provide an economic analysis of a water main geothermal system in a residential space using TRNSYS 18 with the TESS component library package. Provide concrete data that supports the economic feasibility of owning and operating this type of geothermal system. The water main geothermal system was designed using TRNSYS 18 with the TESS component library package. A detailed guide, explaining the procedure for using TRNSYS 18 with the TESS component library package is given. The guide will allow researchers to understand the overall system design including results. This research work will determine the economic feasibility of implementing a water main geothermal HVAC system in a residential space using TRNSYS 18 to simulate the performance.

Committee: Yong Tao Dr. (Advisor); Wei Zhang Dr. (Committee Member); Navid Goudarzi Dr. (Committee Member); Ungtae Kim Dr. (Committee Member) Subjects: Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2017, Renewable and Clean Energy

Photovoltaic-thermal (PVT) technology is a relatively new technology that comprises a photovoltaic (PV) panel coupled with a thermal collector to convert solar radiation into electricity and thermal energy simultaneously. Since cell temperature affects the electrical performance of PV panels, coupling a thermal collector with a PV panel contributes to extracting the heat from the latter to improve its performance. In order to ensure a sufficient temperature difference between the PV cells and the working fluid temperature entering the thermal collector, the circulated water has to reject the heat that has been removed from the PV cells into a relatively colder environment. Borehole thermal energy storage (BTES), which is located underground, often serves as this relatively colder environment due to the stability of underground temperatures, which are usually lower than the working cell temperature. Use of BTES is especially beneficial in summer, when the degradation in cells efficiency is highest. In this thesis, the electrical, thermal, and economic performances of a PVT system are evaluated for three types of buildings -- residential, small office, and secondary school -- in two different climates in the United States, one of which is hot and the other is cold. For each case, two different scenarios are considered. In the first, a PVT system is coupled with BTES, and a ground-coupled heat pump (GCHP) is in use. In the second, a PVT system is coupled with BTES and no GCHP is in use. Each scenarios' GCHP performance is assessed as well. Both the PVT collectors and GCHP performances are evaluated over short and long-term to study the effect of continued ground heat imbalance on both technologies.

Committee: Andrew Chiasson Ph.D. (Committee Chair); Youssef Raffoul Ph.D. (Committee Member); Robert Gilbert Ph.D. (Committee Member) Subjects: Energy; Engineering; Mechanical Engineering