Master of Science (MS), Ohio University, 2014, Geological Sciences (Arts and Sciences)

Traditionally, geothermal resources have required access to large amounts of heat, often in tectonically active basins. More recently, Ground Source Heat Pumps (GSHP) have been used for heating and cooling applications in basins with less heat available in the shallow crustal material. Conventionally, GSHPs exchange heat with either saturated or unsaturated soils or bedrock, or water, at an increased efficiency compared to traditional heating and cooling systems. This study is focused on characterizing the potential of using flooded abandoned underground mines (AUM) in Ohio for heat exchange using GSHP technology. This study identified 147 possible mine sites, spanning 21 counties, which might be used for GSHP installations in Ohio. The mines have an estimated average maximum residence time of 6 years and an estimated average minimum residence time of 3.5 years. It was estimated here that, on average, 1010 kJ/°C of heat energy could be extracted from the mine waters. An individual site study was investigated for possible GSHP application, at the Corning Mine Complex in Perry County, Ohio. Temperature and hydraulic head sensors were installed into monitoring wells drilled into the mine void. The results from the Corning study show that the mine is thermally stable throughout the year and that the average temperature within the mine void is related to the thickness of overburden above the void. The residence time of water within the mine is 3.6 years with an extractable heat of 3.45 x 1010 kJ/°C. Overall, this study has shown that there is sufficient heat available within AUMs for heat exchange using GSHP technologies and that these mines could be a valuable resource for heating and cooling applications in Ohio.

Committee: Dina Lopez (Advisor) Subjects: Environmental Geology; Geochemistry; Geology; Hydrology

MS, University of Cincinnati, 2022, Engineering and Applied Science: Civil Engineering

Building electrification defines the shift to use electricity in place of non-renewable resources and has become a common avenue for reducing greenhouse gas (GHG) emissions. Replacing combustion-fueled heating systems with heat pumps, specifically air-source heat pumps, is the most common path to building electrification as installation increases in the U.S. However, in regions where the electricity generation is made up of predominately coal, gas, and other non-renewable resources, building electrification through heat pump installation can actually increase GHG emissions and raise annual utility costs for heating and cooling. To avoid this issue, other energy efficiency measures, such as building weatherization, should be considered before electrification. This thesis models energy use for a mid-rise multi-family building in Cincinnati, OH to determine if it is more beneficial to prioritize weatherization measures over building electrification based on system and building envelope efficiency, electricity fuel mix, and utility costs. Twenty different building energy models were run to compare GHG emissions and utility cost savings for replacing a low, medium, and high efficiency existing natural gas furnace with an air source heat pump (ASHP) along with three different weatherization measures. Results of this thesis conclude that weatherization measures achieve more savings than furnace replacement alone for medium and high efficiency furnaces and maximum savings are achieved when weatherization measures and natural gas furnace replacement are combined. This indicates that electrifying building heating systems in Cincinnati will result in savings, but weatherization measures are the best first step to take if deciding between weatherization and electrification.

Committee: Amanda Webb Ph.D. (Committee Member); Leah Hollstein Ph.D. (Committee Member); Hazem Elzarka Ph.D. (Committee Member) Subjects: Energy

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

Doctor of Engineering, University of Dayton, 2021, Mechanical Engineering

One way to reduce conventional energy consumption is through the use of a vertical ground-coupled heat pump (GCHP) systems where heat is charged/discharged to/from the ground by an array of grouted vertical borehole heat exchangers. Although this technology is promising to increase the efficiency of heat-pumps, the main obstacle is the high initial cost. This work examines the viability of one possibility means to overcome the first cost challenge, which is to add micro-encapsulated, paraffin-based phase-change material (PCM) to the borehole grout to dampen the borehole heat exchanger (BHE) peak fluid temperatures. As with any thermal energy storage scheme, its purpose is to reduce the size of equipment and devices required to meet peak loads, and thus the purpose of PCM in this study is to dampen peak temperature response of the borehole, and potentially allow for reduction in design borehole length, and therefore cost, of the borehole array. A numerical analysis of the heat transfer characteristics of a GCHP systems is performed to investigate the effects of adding micro-encapsulated PCM into the borehole grout. The numerical model was completed in COMSOL, where the apparent heat capacity method is used, and validated against experimental data. A parametric study of the PCM thermal properties was conducted to establish design recommendations for the vertical heat exchange borehole grout. Results of this study show that adding PCM into the borehole does not always improve the overall performance of the GCHP system; rather, it could deteriorate the system performance if the PCM thermal properties and melt temperature are not correctly chosen. An optimum mass of PCM exists for borehole grout due to the competing factors of PCM thermal conductivity and its latent heat capacity, but to be effective, the PCM thermal conductivity should be approximately equivalent to that of the grout material. Further, the optimal melt temperature of the PCM was found to be that which (open full item for complete abstract)

Committee: Andrew Chiasson (Advisor); David Myszka (Committee Member); Muhammad Usman (Committee Member); Gilbert Robert (Committee Member) Subjects: Energy; Geophysics; Mechanical Engineering

PhD, University of Cincinnati, 2015, Engineering and Applied Science: Mechanical Engineering

This dissertation presents the fabrication and testing of a new design of an electro-osmotic flow (EOF) driven micro-pump. Considering thermal management applications, three different types of micro-pumps were tested using multiple liquids. The micro-pumps were fabricated from a combination of materials, which included: silicon-polydimethylsiloxane (Si-PDMS), Glass-PDMS, or PDMS-PDMS. The flow rates of the micro-pumps were experimentally and numerically assessed. Different combinations of materials and liquids resulted in variable values of zeta-potential. The ranges of zeta-potential for Si-PDMS, Glass-PDMS, and PDMS-PDMS were –42.5 to –50.7 mV, –76.0 to –88.2 mV, and –76.0 to –103.0 mV, respectively. The flow rates of the micro-pumps were proportional to their zeta-potential values. In particular, flow rate values were found to be linearly proportional to the applied voltages below 500 V. A maximum flow rate of 75.9 µL/min was achieved for the Glass-PDMS micro-pump at 1 kV. At higher voltages non-linearity and reduction in flow rate occurred due to Joule heating and the axial electro-osmotic current leakage through the silicon substrate. The fabricated micro-pumps could deliver flow rates, which were orders of magnitude higher compared to the previously reported values for similar size micro-pumps. It is expected that such an increase in flow rate, particularly in the case of the Si-PDMS micro-pump, would lead to enhanced heat transfer for micro-chip cooling applications as well as for applications involving micro-total analysis systems. The Si-PDMS micro-pump was modified to be used as a micro-scale heat exchanger for the thermal management of hot spots generated by microchips. Various cooling liquids including, deionized water, distilled water, borax buffer, and Al2O3 nano-particle solution, were tested and compared based on their flow rates and the increase in the temperature of the cooling liquid. A constant heat flux heater wa (open full item for complete abstract)

Committee: Rupak Banerjee Ph.D P.E. (Committee Chair); Sabyasachi Ganguli Ph.D. (Committee Member); Ajit Roy Ph.D. (Committee Member); Michael Kazmierczak Ph.D. (Committee Member); Teik Lim Ph.D. (Committee Member) Subjects: Mechanics

MS, University of Cincinnati, 2009, Engineering : Mechanical Engineering

Experiments were performed on a heat exchanger equipped with multiple thermoelectric (TE) modules. The primary objective was to design a simple, but effective, modular Peltier heat pump system component to provide chilled or hot water for domestic use. Moreover, the modular design of this system component is such that the total system capacity is scalable such that it can potentially be used for hydronic building climate control of small solar residences, where the TE devices could be directly energized using solar powered PV panels, and coupled with the building inlet water supply heat sink and grey water heat recovery, providing a renewable, pollution free and cost-effective solutions to the home energy problem. First, the work focuses on the design and testing of a thermoelectric heat exchanger component that consists of two water channels machined from two aluminum plates with an array of three or five thermoelectric modules placed in between to cool and/or heat the water. Then the work focuses on the detailed convection analysis inside the TE-HX component when 10 thermoelectric modules are utilized. The local heat transfer coefficient at different points along the channel are measured at steady-state, first, when a continuous heater is installed and then when replaced with 10 TE modules. The experimental heat transfer coefficients obtained are compared with available empirical correlations for developing “transition” (3000 < ReDh < 7000) turbulent flow inside the channel with fair-to-good results. Next, the resulting coefficient-of-performance of the TE heat pump system is measured with its value depending both on system input power and water flow rate. Testing showed that performance degradation, i.e. reduced COPs, occurred when operated at higher power levels but remains satisfactory for up to 688 Watts with higher flow rate. A comparison of the system performance with different TE module arrangements at different power level has also been made which gives th (open full item for complete abstract)

Committee: Dr. Michael Kazmierczak PhD (Committee Chair); Dr. Milind A. Jog PhD (Committee Member); Dr. Sang Y. Son PhD (Committee Member) Subjects: Mechanical Engineering

Doctor of Philosophy, The Ohio State University, 2011, Mechanical Engineering

There is a growing need for advanced energy technologies for alternative and efficient electricity generation as well as the efficient use of energy. The central goal of this research was to develop thermoelectric (TE) device technologies which address the limitations of current TE materials and devices in order to capitalize on the inherent benefits of solid-state TEs. These benefits include reliability, low maintenance, controllability, and high power density. Specifically, this research focused on developing technologies surrounding a multi-fuel combustion-powered thermoelectric generator, a building-integrated thermoelectric heat pump, and a methodology for the frequency domain modeling of thermoelectric devices. The first focus of this research is the development of a multi-fuel combustion-powered thermoelectric generator to exploit the reliability and high power density of thermoelectrics. A baseline prototype was constructed which demonstrated the use of a novel fuel atomizer with diesel fuel and Bi2Te3 thermoelectric modules. In subsequent prototypes, catalytic combustion was incorporated to improve heat transfer to the TE. These catalytic combustion prototypes were tested with propane and demonstrated more than twice the heat transfer effectiveness of the baseline. Thermal characterization of the prototype at 500 °C was used to model its performance with an advanced PbTe module which yielded a peak net power of 8.08 W. Modeling of stacked PbTe/Bi2Te3 modules produced a peak net TE efficiency of 9.07% for a net device efficiency of 3.26%. The models and analysis provided insight into energy flows within the device and identified key areas of focus for future development. The analysis also suggests that device efficiencies of 9%-10% may be achievable using current TE materials and device technologies. The second focus of this research is on the development of a framework for replacing conventional heating and cooling systems with distributed, continuously and (open full item for complete abstract)

Committee: Gregory Washington PhD (Advisor); Yann Guezennec PhD (Committee Member); Joseph Heremans PhD (Committee Member); Giorgio Rizzoni PhD (Committee Member); Junmin Wang PhD (Committee Chair) Subjects: Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2010, Mechanical Engineering

Current and future military aircraft have a critical need for improved avionics heat removal. A drop-in replacement is sought for the existing heat transfer fluid, poly-alpha-olefin (PAO). Nanofluids have been considered for this application due reports of increases in thermal conductivity higher than predicted by conventional theory. In this study, a coolant loop apparatus was designed and built to evaluate the laminar and turbulent heat transfer performance of water-based and PAO-based alumina nanofluids in a flowing system. Alumina/water solutions showed an increase in pressure drop with particle loading which caused the heat transfer coefficient (HTC) at equal pumping power to be lower than at equal flowrates. In turbulent heat transfer, the alumina/water nanofluids show a 1-5% increase in HTC at equal flowrates. At equal pumping power, the nanofluid HTC is lower than water. In laminar flow at equal flowrates the HTC is decreased, which is not predicted. The alumina/PAO nanofluid showed similar pressure drop performance to the pure PAO base fluid. In turbulent flow at equal flowrates and equal pumping power, the HTC increase is only 1-3%. In laminar flow, a similar increase of 1-3% was observed. This increase is too small to warrant further testing of these fluids. In addition, particle settling was observed after only a few hours, which leads to questions about the long term stability of these nanofluids in a continuously flowing system. Overall, the fluids tested showed only marginal enhancement to the heat transfer coefficient. There were no significant (i.e. order of magnitude) increases observed between the results and conventional theory as have been reported elsewhere. The results of this work show that coolant loop apparatus is a valuable system-level screening tool for the U.S. Air Force to evaluate new single-phase coolants for avionics cooling.

Committee: Robert Wilkens PhD (Advisor); Michael Elsass PhD (Committee Member); George Doyle, Jr PhD (Committee Member) Subjects: Chemical Engineering; Mechanical Engineering

Master of Sciences (Engineering), Case Western Reserve University, 2013, EMC - Aerospace Engineering

The knowledge of the flow fields inside of microsized ionic wind pumps has become more important as the need for smaller and more efficient heat removal devices has increased. Understanding these flow fields will help optimize the ionic wind pumps. Non-intrusive microscale particle image velocemity (PIV) utilizing a microscopic objective lens is used to obtain the flow field inside of the ionic wind pump. Voltages ranging from 1700 to 2000 V are used, as well as seeded flow rates of 1.5 and 1.84 L/min. Computational models are used to qualitatively verify the flow fields. The effects of voltage and seed flow rate are also compared. The computational and PIV flow fields are shown to be very similar. It is shown that as the voltage applied to the ionic wind pump increased, the maximum velocity inside of the ionic wind pump increased, ranging from 1.71 m/s to 3.19 m/s. The average mass flow rate inside of the device also increased as the voltage increased, ranging from .0009 g/s to .0019 g/s. It is also shown that the seed flow rate has little effect on the PIV flow field obtained.

Committee: Jaikrishnan Kadambi Dr. (Advisor); Alexis Abramson Dr. (Committee Member); Yasuhiro Kamotani Dr. (Committee Member) Subjects: Aerospace Engineering