Doctor of Philosophy (Ph.D.), University of Dayton, 2023, Mechanical Engineering

A ground-source heat pump (GSHP) system with an array of solar photovoltaic-thermal (PVT) modules for cooling-dominated buildings is proposed and its thermal performance is analyzed in this study. As individual systems, GSHP and PVT systems have experienced slow market penetration; GSHP systems have relatively high capital cost compared to conventional heating and cooling systems, while PVT systems have only seen niche application in low-carbon new residential buildings. Coupled together, the ground heat exchanger (GHX) could be designed to optimize efficiency of the PV cells, or the PVT array could be designed for thermal management of annual ground thermal load imbalances on the ground heat exchanger (GHX), or some combination of these design approaches. Radiative coolers have seen development and various applications in recent years. Using typical PVT collectors as a nocturnal cooler in addition to their daytime multi-function leads to better space and cost utilization of the PVT system. To examine the merit of such systems, an outdoor experiment was conducted to evaluate the PVT nocturnal performance, and two models were developed to simulate its thermal performance. First, mathematical model was developed with a detailed description of the physical and environmental parameters that affect the PVT nocturnal thermal performance. The mean error between the model and observed experimental data for predicting the fluid outlet temperature was 0.76 ± 0.91 K, indicating that the model is suitable to characterize the nocturnal cooling performance of the PVT module. The nocturnal radiative cooling is influenced by the water vapor content in the atmosphere and clear sky conditions. The nocturnal cooling power was found to increase by up to 45 W/m2 under a favorable radiative cooling condition. Due to the iterative nature of the detailed model, the model is computationally intensive when integrated in iterative system simulation such as the hybrid GSHP system. The detai (open full item for complete abstract)

Committee: Andrew Chiasson (Committee Chair); Rydge Mulford (Committee Co-Chair); Andrew Schrader (Committee Member); Atif Abueida (Committee Member) Subjects: Energy; 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

Doctor of Philosophy (Ph.D.), University of Dayton, 2017, Mechanical Engineering

Combined heat and power (CHP) systems are increasingly used in conjunction with traditional grid power for industrial and residential applications. This technology most often involves the on-site combustion of primary fuel, such that both electrical and thermal energy can be utilized to increase overall efficiency. It is also possible to create electrical and thermal energy from solar radiation, using hybrid photovoltaics and thermal (PVT) collectors. These are designed to lower the photovoltaic temperature, improving electrical efficiency, while providing useful thermal energy. One of the key steps in deploying CHP technology is optimal sizing and energy dispatch for a particular application. This work considers these problems for a natural gas powered CHP in a multi-family residential building in North America, and PVT for desalination in remote areas in the Kingdom of Saudi Arabia (KSA). It has already been established that CHP for building applications can reduce grid power requirement and lower overall energy costs. However, no comprehensive study has considered optimizing CHPs for multi-family residences. Although this type of building represents a significant fraction of overall energy consumption in the US and world, they have been shown to be significantly less efficient than other types of residences. Also, due to significant thermal demand in the form of hot-water, multi-family residences are particularly well-suited for CHP. Two separate natural gas powered CHP designs for a multi-family residence are presented in this work, both conceived as retrofits to an existing building. These designs use historical demand data from an all-electric 120-unit multi-family residence in Columbus, Ohio, US that was built in 2008 to minimum code standards. The first design uses a CHP that operates intermittently to meet partial loads for electricity and hot water in order to reduce overall energy cost, when considering a demand sensitive grid power cost prici (open full item for complete abstract)

Committee: Hallinan Kevin (Committee Chair) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2016, Nuclear Engineering

The objective of this research is to conduct a comparative analysis of polyvinyltoluene (PVT) organic scintillators in order to aid Lawrence Livermore National Laboratory in the design of a PVT scintillator for fast neutron imaging. To achieve this goal, a neutron imaging apparatus has been developed to conduct neutron radiography using a neutron beam facility at The Ohio State University Research Reactor (OSURR). The neutron imaging apparatus is based on a low-cost single mirror refection configuration that consists of a neutron sensitive scintillator, a light tight box, a mirror, and a cooled charge-coupled device (CCD) camera. The light tight box was designed, machined, and built in-house specifically to fit into the space available at the neutron beam facility. The camera position is adjustable within the box in order to provide an adjustable field of view, which allows the object or region of interest to take full advantage of the CCD chip size. The spatial resolution of the scintillator was characterized by using Modulation Transfer Function (MTF) and an optical test target. The light yield was measured by the summation of pixel values in the same region of interest in each scintillator. Maximum resolution for a lithium loaded PVT (1.3% by weight) scintillator with thickness of 2.2 mm was 10.9 lp/mm for thermal neutrons. The resolution decreased by 11% with an increase of 1.1 mm in thickness. For fast neutrons with an average energy of 2 MeV, Li-loading increased the light yield of PVT by 29%. For 2.45 MeV neutrons produced by a D-D neutron generator, PVT with a Europium fluor produced 2.7 ± 0.2 times more light than a standard PVT scintillator. The combination of lithium loading with a Eu fluor in PVT produces an efficient dual-purpose fast and thermal neutron imager, as anticipated.

Committee: Lei Cao (Advisor); Thomas Blue (Committee Member) Subjects: Nuclear Engineering

Master of Science (MS), University of Toledo, 2015, Biomedical Sciences (Medical Physics: Diagnostic Radiology)

Despite continuous improvements in design of HDR brachytherapy delivery systems, the position of the source is still verified only through the HDR afterloader hardware/software based on the length of the wire reeled out relative to the parked position. The position of the source is not independently monitored during the treatment, potentially opening the door to misadministrations. We investigate the feasibility of using dose maps acquired with a two-dimensional diode array to verify the relative source locations and confirm delivered dose during an HDR treatment.Dose maps for the source located at selected distances in air and depths in solid water were acquired with a MapCHECK2TM diode array and the Varian VariSourceTM Ir-192 HDR afterloader. The peak location of the measured dose profile for each dwell position provided the X and Y coordinates while the full width at half maximum (FWHM) of each peak was used to calibrate the source distance along the Z axis. Two treatment orientations were considered with the source moving along 1) the rectangular surface of a solid water phantom and 2) the inclined plane of a paraffin wax wedge to verify the method for both coplanar and non-coplanar source and detector geometries for three source positions. Acquired dose maps were used to restore coordinates of dwell positions.Although the spatial resolution is 10 mm along a row or column of diode detectors, the accuracy in determining dwell position coordinates was found to be within +/-2 mm in the X and Y directions of the diode plane using a polynomial fit to interpolate the values at distances between the measured points. The FWHM was found to increase linearly with source depth/distance, making it a suitable parameter for determining the source Z coordinate. Our studies have verified that the dose maps can be used as a routine QA tool for HDR treatment delivery verification.

Committee: Diana Shvydka Ph.D. (Committee Chair); E. Ishmael Parsai Ph.D. (Committee Member); David Pearson Ph.D. (Committee Member) Subjects: Physics

Doctor of Philosophy, Case Western Reserve University, 1994, Physics

Extensive experimental studies of fluid hydrocarbons in the lubricating range of molar mass have been undertaken sometime ago by American Petroleum Institute Project 42, located in the Departments of Chemistry and Physics at Pennsylvania State University. In these studies systematic structural changes were introduced, so that the equation of state (e.o.s.) as well as the viscosities of linear paraffins, branched hydrocarbons, and various rings attached to n-alkanes tails are known. Hence this material became the basis for various semi-empirical or empirical structural correlations. We proceed here with the hole theory of Simha-Somcynsky (SS) which has proven quantitatively successful for low as well as high molar mass system and examine e.o.s. data. We demonstrate the success of the theory and obtain the characteristic volume (ν*), energy (varepsilon*) and flexibility (c) parameters as functions of chain length for the different structures. For the short chains in question these represent averages over the terminal and internal units. By suitable generalization of the SS theory developed for physical mixtures we decompose these averages into the individual group contributions. The accuracy of the numerical procedures employed is tested by back computations. Sometime ago A. Bondi developed structural rules for the computation of Van der Waals excluded group volumes. Interesting correlations between these and the above ν* values, defined for a 6-12 potential, are obtained. In the same way we examine correlations between D. W. Van Krevelen's and P. J. Hoftyzer's cohesive group energies and varepsilon* values.

Committee: Robert Simha (Advisor) Subjects:

Master of Science, University of Akron, 2008, Physical Education-Exercise Physiology/Adult Fitness

Caffeine is the most widely consumed drug in the world. In various forms, it has been shown to elicit some advantageous effects when ingested prior to exercise. Caffeine has been widely used in the liquid or capsule form for decades now; however caffeine in the chewing gum form is a much more recent development and hence has less established research on it. The purpose of this study is to examine the effects of caffeinated chewing gum on lower body pain and reaction time during exercise. Eight healthy, physically active male participants between 18 and 32 years of age were recruited to participate. Participants reported to the laboratory on five occasions. On the first visit, subjects underwent a graded exercise test on an Excalibur 1300W electronically braked cycle ergometer until volitional fatigue at which time expired air samples were analyzed for oxygen and carbon dioxide concentrations via an automated open circuit system to determine maximal oxygen consumption. The two highest 30-second oxygen consumption values were averaged to determine maximal oxygen consumption. Over the next four visits, 200 milligrams of caffeine chewing gum or placebo were administered in a randomized, counterbalanced, double blind manner at 35 minutes before exercise, 5 minutes before exercise, and 10 minutes following the initiation of exercise. Participants cycled on an Excalibur electronically braked cycle ergometer at 85% capacity as determined by expired air samples collected every 10 minutes of exercise which were analyzed for oxygen and carbon dioxide concentrations via an automated open circuit system (PARVO, Metabolic Cart, Sandy, Utah). Participants cycled until volitional fatigue. Lower body pain measurements were obtained every 10 minutes during exercise via a 1-10 pain scale. Reaction time was measured at three time points via a hand held psychomotor vigilance test. For statistics, a Mixed Model Analysis was run. There was no statistical significance in the reduction of r (open full item for complete abstract)

Committee: Ronald Otterstetter PhD (Advisor) Subjects: Behaviorial Sciences; Biomedical Research; Health; Health Care; Pharmacology; Physical Education; Sports Medicine

Master of Mathematical Sciences, The Ohio State University, 2013, Mathematics

Sleep inertia is known to cause delayed reaction times and general performance deficits immediately after awakening, but specifics manifested in children are not well defined. This research aims to elucidate the effects of sleep inertia in children aged 5 to 12. Results were that younger children sustained slower reaction times than older children at baseline and upon awakening. All age groups had greater impairment after a second awakening, possibly due to a circadian effect and/or cumulative fatigue. All groups had improved reactions in the final 2 minutes of testing compared to the first 2 minutes after awakening (though reaction times were still slower than at baseline), suggesting partial recovery in sleep inertia with increased time. Recovery from sleep inertia may be due to wake-promoting neuromodulators; the increase in concentration may be responsible for improved performance with extended time awake. The current study constructs a model based on volume transmission of these neuromodulators. The model is capable of producing results similar to those observed in individuals with little variance in reaction time, but the model struggles to produce adequate replications of more variable data. Furthermore, the model cannot produce many of the dynamics found in the observed data, suggesting that the current model, if appropriate at all, requires many alterations.

Committee: Best Janet PhD (Advisor); Splaingard Mark MD (Advisor); Dawes Adriana PhD (Committee Member) Subjects: Mathematics