Master of Science (M.S.), University of Dayton, 2023, Aerospace Engineering

The main objective of this project is to investigate the performance of Phase Change Materials as the Heat Exchange media in a solar thermal propulsion system. The secondary objective is to visualize and develop the solar thermal propulsion system by running various ground tests using a solar simulator as power source. The project involves design, modelling and fabrication of a bench scale Solar Thermal Propulsion System that can be used to carry and deliver satellites to Moon or Mars' orbit from LEO. PCM's are essential for space travel since the solar energy needs to be stored for the spacecraft to successfully complete the interplanetary missions which consume time and fuel. Without the energy storage system, the spacecraft might need to use conventional fuel ignition systems, which cost money to manufacture and implement in the spacecraft. In this system, the energy from solar light is concentrated into a small cavity through a parabolic reflector and is used to heat the PCM, which in turn heats the propellant and directs it through the nozzle to provide thrust adequate to travel in space. The prototype of the system is first designed using a CAD software and later fabricated into a bench scale model. The model is then set up in the laboratory and connected to a high flux solar simulator. Computational simulations and some test runs of the physical model would be conducted to analyze the performance of PCM in this system

Committee: Rydge Mulford (Committee Chair); Andrew Schrader (Committee Member); Jamie Ervin (Committee Member) Subjects: Aerospace Engineering; Energy; Mechanical Engineering

Master of Science (M.S.), University of Dayton, 2018, Renewable and Clean Energy

The off-grid location and unreliable electricity supply to medical clinics in remote parts of India make it difficult to safely store vaccines and other medications using traditional refrigeration systems. The Engineers in Technical Humanitarian Opportunities of Service-learning (ETHOS) program at the University of Dayton, in collaboration with Solar Alternative and Associated Programmes (SAAP) of Patna India, are developing a novel refrigeration system which works on the principle of solar thermal adsorption. This refrigeration system does not require electricity for operation and uses safe, environmentally benign and locally available adsorption pair of ethanol-activated carbon. A bench -scale prototype was developed at the University of Dayton using ethanol-activated carbon as working pair which can generate evaporative temperatures between 2°C and 8°C. The existing horizontally oriented system can achieve targeted refrigeration temperatures (2 - 8°C) during the adsorption cycle and ethanol can be desorbed from the activated carbon during desorption. However, the horizontal geometry inhibited the return of liquid ethanol to the evaporation chamber. A new vertical oriented bench scale system was built to addresses the limitation of the original prototype. The effects of desorption heating temperature, desorption time duration, double activation of activated carbon on evaporative cooling, and possible decomposition of ethanol during desorption were analyzed. Experimental results suggested better desorption happens at elevated temperature (90-125°C) and most of the desorption happens in the first 1-2 hours of heating the adsorbent bed. The high pressure on the evaporator side for multiple adsorption-desorption process, and analysis of GC/MS of desorbed ethanol obtained from the analytical chemist showed possible decomposition of ethanol. The ethanol decomposition prevented multiple cycle operation of the system. The use of double activation techn (open full item for complete abstract)

Committee: Amy Ciric Ph.D. (Committee Chair); Jun Ki Choi Ph.D. (Committee Chair); Li Cao Ph.D. (Committee Member) Subjects: Alternative Energy; Chemical Engineering; Chemistry; Climate Change; Energy; Engineering; Environmental Science; Experiments; Materials Science; Mechanical Engineering

Master of Science in Mechanical Engineering, Cleveland State University, 2020, Washkewicz College of Engineering

Solar power has been identified as key technology required for extensive exploration of the moon and space. However, solar cell design so far has been based on earth and earth orbit environments, which is vastly different from the lunar surface. The Photovoltaic Investigation on the Lunar Surface (PILS) is a small payload carrying a set of solar cells of the latest technology to the moon in order to test the cells' feasibility and viability in the lunar environment. The objective of this thesis is to analyze the PILS payload design in its mission environments and optimize the thermal design to ensure that the critical components remain within their survival limits throughout transit and within operational temperature limits during lunar surface operations. The thermal analysis software Thermal Desktop was used to create a thermal model of the PILS payload which was analyzed in transit, three lunar orbits, descent and lunar surface operations in order to optimize the payload's active and thermal design. This thesis discusses the thermal model in detail which includes the geometry, conduction through the assembly, environmental conditions, and orbital definitions. The thermal model was then analyzed to investigate the temperature change in each component in all environments with the critical electronic components. The active thermal protection, heaters, were optimized for a “0 sink” case where the PILS payload was assumed to be in deep space – with no view to the sun or the moon for solar, albedo or planetshine heating. The passive thermal protection design was optimized for the hottest scenario in this mission: lunar noon during surface operations on the moon. Finally, the effects on the PILS payload from landing off-nominally on the lunar surface was also analyzed. The results show that the overall thermal design is successful in keeping all critical components within their operational temperature range throughout the entire mission.

Committee: Maryam Younessi Sinaki PhD. (Advisor); Tushar Borkar PhD. (Committee Member); Brian Motil PhD. (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

Master of Science (M.S.), University of Dayton, 2024, Mechanical Engineering

The goal of this work is to analyze and characterize solid granular media in high temperature CSP applications. This work expands on commercially available Discrete Element Method (DEM) modeling software, Aspherix®, through development of two calibration templates designed to mimic both the experimental rigs for the slump test and rotary kiln discussed in this thesis. Whereas, designed experimental rigs were developed to isolate desired frictional behaviors in three different material types (CarboBead HSP, CarboBead CP, and Granusil) for temperatures varying from 25°C – 800°C. Additionally, improvements were made upon the previously constructed rotary kiln to facilitate high temperature testing experimentally.

Committee: Andrew Schrader Dr. (Advisor) Subjects: Mechanical Engineering

Master of Science, The Ohio State University, 2005, Graduate School

Committee: Not Provided (Other) Subjects:

Master of Sciences, Case Western Reserve University, 2022, Physics

The increasing adoption of renewable sources of electricity (i.e. wind and solar farms) is being driven by the demand for carbon neutral electricity production. Although zero carbon is emitted during electricity production, these renewable energy sources suffer from intermittency, which is a mismatch between the supply and demand of electricity of the grid. Renewable energy sources, such as wind and solar, produce their peak electricity at off-demand periods of the day. This strains the electrical grid as it risks over-generation in some locations as well as a need for quick ramping of the electrical load which is hard on electricity producing infrastructure. As a partial solution to intermittency, pumped storage hydropower (PSH) is the dominant form of grid-scale energy storage. PSH accounts for 95% of the U.S. grid-scale storage capacity, which amounts to 22.9 GW of capacity [1]. The EIA also estimates with all possible sites, the U.S. can double their PSH capacity [1]. However, much more than that is not feasible being constrained by the availability of locations suitable for PSH. As a result, other gridscale energy storage options are in development. The main options include batteries, thermal energy storage, compressed air energy storage (CAES) and flywheels. However, these storage options are plagued by high cost per kWh prices, location specificity (ex. PSH, CAES) and/or low energy density. With these concerns in mind, Cratus LLC is developing a molten salt thermal energy storage option known as ThermaBlox, which is location-independent, low-cost, and high-capacity (with the capability to scale). ThermaBlox will play a significant role in intermittency reduction while enabling increased adoption rates of renewable energy.

Committee: Edward Caner (Committee Chair); Dr. Benjamin Monreal (Committee Member); Dr. Robert Brown (Committee Member) Subjects: Chemical Engineering; Energy; Engineering; Entrepreneurship; Fluid Dynamics; Mathematics; Nanotechnology; Physics; Technology

Doctor of Philosophy, University of Toledo, 2019, Physics

Evaluation and understanding of optical properties are essential for the use and design of optoelectronic devices. This dissertation explains the evaluation of optical properties of component layers of the encapsulated photovoltaic (PV) module and uses them in device simulation focusing on thermal management. Sub-bandgap characterizations are not emphasized enough in the PV device design earlier. The examples discussed here range from ordinary glass used to cover solar cells to completed silicon (Si) wafer and thin film cadmium telluride (CdTe) solar cells. This study will focus on two key mechanisms for thermal management: radiation and sub-bandgap reflection. Commercial solar cells have light incident through the glass in solar wavelength range ~250- 2500 nm. This cover glass has an ability to re-radiate heat in the infrared (IR) region, thermal wavelength, from the device to keep the solar cells cool. In contrast to bare semiconductors, glass has a relatively high emissivity aiding in radiative cooling of solar modules. The directional thermal emissivity of solar cell cover glasses with differences in glass composition or manufacture and surface texture are evaluated using specular and specular+diffuse infrared reflectance at a different angle of incidences. Non-textured and textured glasses all exhibit similar emissivity at all angles of incidence regardless of composition and patterning. Both diffuse and specular reflectance must be included for textured glass at any angle of incidence and may be needed for planar glass at a high angle of incidences to determine emissivity accurately. Optical characterization of the semiconductor is important from the perspective of physics and application in devices. There are different features in the optical response related to different physical phenomena such as band to band electronic transitions, vibrational or phonon modes, and free carrier absorption. I have explored optical properties of an epitaxial indium pho (open full item for complete abstract)

Committee: Nikolas Podraza (Committee Chair); Robert Collins (Committee Member); Yanfa Yan (Committee Member); Sanjay Khare (Committee Member); Michael Deceglie (Committee Member) Subjects: Physics

Bachelor of Science (BS), Ohio University, 2018, Engineering Physics

To date, solar energy has been primarily captured through the use of solar panels, which employs the direct conversion of light to electricity (photovoltaics).[1, 2] However, efforts in absorbing the light and converting it into heat (solar thermal) have been largely neglected.[3] This thesis describes an investigation into the latter of the two: solar thermal. The large capital requirement for mirrors and lenses in concentrating solar power (CSP) plants has led many to favor photovoltaics (PV) over CSP and thus over solar thermal technologies.[3] The high cost of mirrors and lenses presents an obstacle for CSP, but does not explicitly do so for solar thermal technology as a whole. Thermal concentration is able to accomplish the same end goal as CSP (optical concentration) while requiring much less capital cost. Specifically, selective absorbers offer a promising method in thermal concentration applications. In this thesis, we investigate the solar thermal potential of various titanium nitride structures as spectrally selective absorbing materials.

Committee: Martin Kordesch (Advisor); Hugh Richardson (Advisor) Subjects: Energy; Engineering; Physics

Bachelor of Science (BS), Ohio University, 2018, Chemistry

Optical heating has numerous applications, such as cold weather clothing, heat generation for homes, and solar thermal generation of electricity. One form of this optical heating technology is the fabrication of poly (methyl methacrylate) polymer thin films with embedded nanoparticles, such as titanium nitride and carbon black. MATLAB was used to simulate samples, in order to determine the optimal configuration for most heat generated. The optimal configuration was carbon black nanoparticles with a radius of 900nm, packed closely together (1800 nm apart), in a medium such as aerogel with low thermal conductivity, with a maximum mass of carbon black and minimal thickness of the sample.

Committee: Hugh Richardson (Advisor); Lauren McMills (Advisor) Subjects: Chemistry

Master of Science in Renewable and Clean Energy Engineering (MSRCE), Wright State University, 2016, Renewable and Clean Energy

Most applications of flat plate, low-temperature solar thermal panels are for water heating, such as producing domestic hot water or raising the temperature of swimming pools. This is reasonable given that the large masses of water present in these systems inherently provide built-in thermal energy storage so that a separate energy storage tank does not have to be purchased. For a space heating system, extra thermal energy storage generally has to be purchased and is a detriment to the economics of these systems. Despite the economic drawbacks of solar thermal space heating, this thesis focuses on the size of thermal systems required to heat an average size home in Minneapolis, MN and Dayton, OH. For these two locations and for a standard test case, this thesis studies the effect of solar panel size and orientation, heat exchanger size, and operation parameters including flow rates through the solar panels and heat exchanger. Liquid, flat plate collectors are one of the simplest methods for collecting solar energy. These panels are generally inexpensive and can have collection efficiencies above 50%. This makes solar thermal panels more efficient than solar photovoltaic panels, which generally have efficiencies less than 20%. Since the solar thermal panels chosen for study in this work heat a liquid with the sun's energy and the fluid being heated in the building is air, a heat exchanger has to be included in the model. Lastly, because solar thermal systems are inherently unsteady, thermal energy storage must be included in the model. These components of a solar thermal space heating system are modeled by writing and adding routines to the Wright State developed simulation program called Solar_PVHFC. Solar_PVHFC is a simulation program which models solar photovoltaic panels coupled with fuel cells and hydrogen storage tanks. Because of this work, Solar_PVHFC is now capable of modeling a solar thermal system. The advantage of coupling this solar thermal work to So (open full item for complete abstract)

Committee: James Menart Ph.D. (Advisor); Allen Jackson Ph.D. (Committee Member); Amir Farajian Ph.D. (Committee Member) Subjects: Mechanical Engineering

Master of Science, University of Toledo, 2011, Electrical Engineering

During the last decade, organic photovoltaic research has attracted attention and power conversion efficiencies have shown strong growth. This growth has attracted economic and scientific interest towards organic solar cell. This attention was possible due to the introduction of new polymer materials, inorganic molecules, sophisticated methods of fabrication, and improved material technologies. Bulk-Hetero Junction solar cells achieved 7 % efficiency with the introduction of inorganic small molecules in organic polymers. Organic solar cells of 12% efficiency are targeted. However, the degradation of organic semiconductors due to the environment and the effect of cathode deposition make the organic solar cells inferior to silicon solar cells. In this thesis, the effect of cathode deposition with various deposition methods was studied. The Dark Capacitance-Voltage characteristics and Capacitance-Frequency characteristics Of MEH PPV (Poly (p-phenylene vinylene) (PPV)) Solar cell with sputtering and thermal evaporation of the aluminum cathode are reported here. Capacitances are measured at different temperatures using cryogenic testing. Interface state densities and their time constants are calculated and analyzed. The variance of depletion width, interface state densities and time constants with two different processes is discussed here. The observations indicated that rf sputtering deposition of cathode is introduces greater interface densities compared to thermal evaporation devices

Committee: Rashmi Jha Dr (Committee Chair); Maria Coleman Dr (Committee Member); Vijay Devabhakthuni Dr (Committee Member); Mansoor Alam Dr (Committee Member) Subjects: Electrical Engineering