Doctor of Philosophy (Ph.D.), University of Dayton, 2020, Mechanical Engineering

This dissertation focusses mainly on loads determination, building informatics, and geothermal energy systems. The first chapter is Low-Energy Opportunity for Multi-Family Residences: A Simulation-Based Study of a Borehole Thermal Energy Storage System. In this chapter, we propose a district borehole thermal solar energy storage (BTES) system for both retrofit and new construction for a multi-family residence in the Midwestern United States, where the climate is moderately cold with very warm summers. Actual apartment interval power and water demand data was mined and used to estimate unit level hourly space and water heating demands, which was subsequently used to design a cost-optimal BTES system. Using a dynamic simulation model to predict the system performance over a 25-year period, a parametric study was conducted that varied the sizes of the BTES system and the solar collector array. A life-cycle cost analysis concluded that is it possible for an optimally-sized system to achieve an internal rate of return (IRR) of 11%, while reducing apartment-wide energy and carbon consumption by 46% The promise for district-scale adoption of BTES in multi-family residences is established, particularly for new buildings. In the second chapter (Alternate Approach to the Calculation of Thermal Response Factors for Vertical Borehole Ground Heat Exchanger Arrays Using an Incomplete Bessel Function), we presents another methodology for the calculation of dimensionless thermal response factors for vertical borehole ground heat exchanger (GHX) arrays, which is a concept introduced by Eskilson (1987). The presented method is based on a well-known solution to an analogous problem in the field of well hydraulics. This solution method, known mathematically as an incomplete Bessel function, and known in the field of well hydraulics as the `leaky aquifer function', describes the hydraulic head distribution in an aquifer with predominantly radial flow to a well combined with vertical (open full item for complete abstract)

Committee: Kevin P Hallinan Professor (Committee Chair); Andrew D. Chiasson Professor (Committee Member); Robert J. Brecha Professor (Committee Member); Robert B. Gilbert Professor (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2019, Environmental Science

Reducing carbon dioxide (CO2) emissions is one of the most pressing issues facing the electricity system. Towards this end, prior work investigated generating electricity with geologically stored CO2 by using it to extract heat from sedimentary basins geothermal resources. This dissertation expands on this idea by developing and valuing approaches for CO2-based energy storage. In the first chapter, we investigate the value that three bulk energy storage (BES) approaches have for reducing system-wide CO2 emissions and water requirements: CO2-Bulk Energy Storage (CO2-BES), which is a CO2-based energy storage approach that uses a concentric-ring, pressure based (CRP-BES) design, Pumped Hydro Energy Storage (PHES), and Compressed Air Energy Storage (CAES). Our results suggest that BES could decrease system-wide CO2 emissions by increasing the utilization of wind, but it can also alter the dispatch order of regional electricity systems in other ways (e.g., increase in the utilization of natural gas power capacity and of coal power capacity, decrease in the utilization of nuclear power capacity). While some changes provide negative value (e.g., decrease in nuclear increased CO2 emission), the system-wide values can be greater than operating cost of BES. In the second and third chapters, we investigate two mechanisms for using CO2 for energy storage: storage of (1) pressure and (2) heat. For pressure storage, we investigated the efficacy of the CO2-BES system using the CRP-BES design over cycles of varying durations. We found that CO2-BES could time-shift up to a couple weeks of electricity, but the system cannot frequently dispatch electricity for longer durations than was stored. Also, the cycle duration does not substantially affect the power storage capacity and power output capacity if the total time spent charging, discharging, or idling is equal over a multi-year period. For thermal energy storage, we investigated the efficacy of using pre-heated CO2 and pre-h (open full item for complete abstract)

Committee: Jeffrey Bielicki (Advisor); Ramteen Sioshansi (Committee Member); Gil Bohrer (Committee Member); Brent Sohngen (Committee Member) Subjects: Alternative Energy; Energy; Engineering; Environmental Economics; Environmental Science

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

Master of Science (MS), Ohio University, 2020, Environmental Studies (Voinovich)

Ground source heat pumps (GSHPs) have been used for heating and cooling applications in areas where the thermal gradients are normal. Unlike conventional heating and cooling systems, ground source heat pumps rely on ground or underground water temperature which is more constant than air temperature. Abandoned underground coal mines (AUMs) have been used as heat exchangers for ground source heat pumps in countries such as Nova Scotia, the Netherlands and states like Pennsylvania. Ohio has around 147 abandoned underground mines located close to towns and with sufficient water and heat available in the groundwater for heat exchange using ground source heat pumps. This project characterizes the potential of the AUM AS-029 located in Athens, Ohio, as a reservoir for GSHP technology in Ohio University or The Plains. Monitoring of the hydraulic and thermal response of groundwater wells around the mine was performed and a hydrogeological model was constructed in Visual MODFLOW to better understand the flow of water through the mine. Additionally, a thermal model of the mine was created considering the overburden thickness of the mine. Three monitoring wells were studied, one to the north of the mine and 2 to the South in The City of Athens well field in the Hocking River valley. Groundwater in the 4 wells respond to precipitation and changes in ambient temperature with a higher response in the wells with lower depth. One of the City of Athens wells, A10, has an unusual response with a high conductivity due to a nearby underground salt deposit. Ground water modeling and modeling of the heat absorbed by the mine shows that mine AS-029 can be used to receive heat, it cannot be used to give heat due to the low temperature of the groundwater in this area. The volume of water that circulates through the mine is not easily exchanged since only 0.03% is exchanged every day and it takes 2,900 days to substitute 100% of the water within the mine. For a change in temperature in the mi (open full item for complete abstract)

Committee: Dina López Dr. (Advisor); Natalie Kruse Daniels Dr. (Committee Member); Daniel Che Dr. (Committee Member) Subjects: Energy; Environmental Geology; Environmental Science; Environmental Studies; Geology; Hydrologic Sciences; Hydrology

Master of Science (MS), Ohio University, 2008, Geological Sciences (Arts and Sciences)

The Berlin hydrothermal field in El Salvador, Central America is located in the San Simon River Basin on the northwest slope of the Berlin-Tecapa volcanic complex, in the eastern portion of the country. This hydrothermal field is a liquid-dominated system governed by fault structures allowing infiltration and transport of meteoric fluids. Exploitation involves the removal of hot fluids from the geothermal reservoir and re-injection of lower temperature fluids. This study analyzes the surficial hydrology and groundwater storage change (since exploitation) in the hydrothermal reservoir to produce a water budget. Field monitoring of springs, fumarole activity, domestic wells, tributaries to the San Simon River, and meteorologic data provide constraints on the hydrology. A correlation between the composition of the fumarolic gases and the diffuse flux of soil CO2 was performed to complete the balance. An analysis of the increase in chloride concentration with time in the deep aquifer and the net mass withdrawn from this aquifer allow an estimation of the decrease in storage in the hydrothermal aquifer. This water balance will assist future operations in optimization and sustainability of the geothermal reservoir and could be used to evaluate extraction and re-injection procedures.

Committee: Dina L. Lopez Ph.D. (Advisor); Gierlowski-Kordesch Elizabeth (Other); Gregory Nadon (Other) Subjects: Geology

Master of Science in Mechanical Engineering, Cleveland State University, 2008, Fenn College of Engineering

The issue being examined is to design a more economical and efficient therefore superior geothermal system than currently in use in industry. Current geothermal systems are designed and built 300 feet into the ground. After researching ground temperature gradients for Ohio we found out that below 10 feet of depth, the temperature varies by 1 degree Fahrenheit per 100 feet depth. Our goal is to utilize the heat as close to the surface as possible and greatly reduce the need to dig so deeply into the ground. The procedure used to go about designing a superior geothermal system is to model an oversized tank going down about 50 feet in depth. Then analyze the model using ground temperature gradient data and the SINDATHERMAL Analyzer program. By investigating different glycol flow rates, glycol supply temperatures, and tank dimensions we are able to investigate various designs and analyze the results for optimization. Our results were such that by using our central tank design we were able to design a Geothermal system superior in terms of performance, construction costs, and operating costs to what is in use in industry today. Our conclusion is that there is no need to drill down 300 feet using traditional Geothermal designs when, by using our design, drilling down 50 feet and using a central tank will result in superior heat flow.

Committee: Rama Gorla PhD (Committee Chair); Earnest Poulos PhD (Committee Co-Chair); Majid Rashidi PhD (Committee Member); Asuquo Ebiana PhD (Committee Member) Subjects: Energy; Engineering; Environmental Engineering; Geotechnology; Mathematics; Mechanical Engineering