Matching Items (193)
Description
The research analyzes the transformation of wasted thermal energy into a usable form through thermogalvanic devices. This technology helps mitigate international growing energy demands. Building energy efficiency is a critical research topic, since the loads account for 40% of all energy demand in developed nations, and 30% in less developed nations. A significant portion of the energy consumed for heating and cooling, where a majority is dissipated to the ambient as waste heat. This research answers how much power output (µW·cm-2) can the thermogalvanic brick experimentally produce from an induced temperature gradient? While there are multiple avenues for the initial and optimized prototype design, one key area of interest relating to thermogalvanic devices is the effective surface area of the electrodes. This report highlights the experimental power output measurements of a Cu/Cu2+ thermogalvanic brick by manipulating the effective surface area of the electrodes. Across three meshes, the maximum power output normalized for temperature was found to be between 2.13-2.87 x 10-3 μWcm-2K-2. The highest normalized power output corresponded to the mesh with the highest effective surface area, which was classified as the fine mesh. This intuitively aligned with the theoretical understanding of surface area and maximum power output, where decreasing the activation resistance also reduces the internal resistance, which increases the theoretical maximum power.
ContributorsKiracofe, Ryan Moore (Author) / Phelan, Patrick (Thesis director) / El Asmar, Mounir (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Current applications of the traditional vapor-compression refrigeration system are not feasible. Space cooling and refrigeration systems that employ vapor-compression refrigeration cycles utilize harmful refrigerants, produce large amounts of carbon dioxide, and have high energy consumption. Adsorption cooling technology is seen as a possible alternative to traditional vapor-compression refrigeration systems. The low-grade heat requirement and eco-friendly adsorbent and refrigerant materials make adsorption cooling an attractive technology. Adsorption cooling technology employs the adsorption principle—the phenomenon in which an adsorbate fluid adheres to the surfaces and micropores of an adsorbent solid. The purpose of this study was to explore the adsorption cooling process through the use of a prototype adsorption test bed design. A basic intermittent adsorption cooling cycle was utilized for the test bed design. Several requirements for the design include low-cost, simple fabrication, and capable of holding a vacuum. In this study, an experiment was carried out to analyze the desorption process, in which the original weight of adsorbed water was compared to the weight of the desorbed water. The system pressure was decreased to sub-atmospheric absolute pressure of 16.67 kPa in order to increase the desorption rate and drive the desorption process. A hot water pump provided 81.6 °C hot water to heat the adsorption bed. The desorption process lasted for a duration of 162 minutes. The experiment resulted in 3.60 g (16.04%) of the initial adsorbed water being desorbed during the desorption process. The study demonstrates the potential of adsorption cooling. This paper outlines the design, fabrication, and analysis of a prototype adsorption cooling test bed.
ContributorsCaballes, Christopher C. (Author) / Phelan, Patrick (Thesis director) / Bocanegra, Luis (Committee member) / School for Engineering of Matter,Transport & Enrgy (Contributor) / Mechanical and Aerospace Engineering Program (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
Photovoltaic panels are commonly used for their versatility in on-site generation of clean electricity in urban environments, specifically on rooftops. However, their implementation on rooftops poses potential (positive and negative) impacts on the energy use of buildings, and urban climates. The negative impacts are compounded if PV is installed on top of a high-albedo rooftop. This study quantitively investigates these impacts from PV installation on top of a building with a white roof in Phoenix, AZ. We supplemented our measurements with EnergyPlus simulations to model the energy implications for archetypical residential and retail buildings and calculated the energy penalty to generation ratio as well as sensible heat flux for each combination of panel height and building type. Results indicate that the daily cooling energy penalty to due blockage of outgoing longwave radiation can be 4.9—11.2% of the PV generation. In addition, while we observed a small decrease in nighttime sensible heat flux to the ambient, PV cases increased the daytime heat flux by more than a factor of 10. This study highlights the potential unintended consequences of rooftop PV under certain conditions and provides a broader perspective for building designers and urban planners.
ContributorsBrown, Kyle (Author) / Sailor, David (Thesis director) / Phelan, Patrick (Committee member) / Department of Physics (Contributor) / Dean, W.P. Carey School of Business (Contributor) / School of Sustainability (Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Description
This thesis research project seeks to provide an investigation to find the most appropriate organogel serving as a lithium ion battery separator that is compatible with stretchable electronics. Separators play a key role in all batteries. Their main function is to keep the positive and negative electrodes apart to prevent electrical short circuits and at the same time allow rapid transport of ionic charge carriers that are needed to complete the circuit during the passage of current in an electrochemical cell [1].Li-ion batteries have become important in the field of electronic industry due to their advantages like compactness, lightweight, high operational voltage and providing highest energy density. Typical Li-ion battery has a cathode (LiCoO2, LiMnO2, LiFePO4 etc.), an anode (graphite, graphene, carbon nanotubes, carbon nanofibers, lithium titanium oxides etc.) and a separator [1]. The separator provides an electrical insulation between anode and cathode and allows ion transfer during operation. It also plays a significant role in determining battery performance. The performance of the Li-ion battery separator is determined by several factors such as permeability, porosity, electrolyte uptake capacity, mechanical, thermal and chemical stability. Several commercially available polymers have been used as separators and the most common polymers are poly(ethylene), poly(propylene), poly (ethylene oxide), poly(acrylonitrile), poly (methyl methacrylate) and poly (vinylidene fluoride) (PVDF) [3]. In this project, organogels were chosen because of their flexible, semi-permeable and reliable bendable characteristics which becomes useful in stretchable batteries. The first part is to use Polydimethylsiloxane (PDMS) which belongs to a group of polymeric organosilicon compounds that are commonly referred to as silicones, then mixed with hexane and sucrose solvents to make the required organogel. Different organogels from PDMS and Dragon skin in different amounts and conditions were created and tested to see what works best in stretchable lithium batteries, thus improving the battery’s efficiency and life cycle. Ion conductivity values were obtained after running the Electrochemical Impedance Spectroscopy Test. Graphs produced after this test proved that the most effective combination to use was at a porosity of 0.8, at a ratio of Sucrose: PDMS wt Ratio of 5: 0.764 respectively. The future endeavors of this project will involve working with reduced cell thickness so as to reduce the overall distance traveled by the ions, which also reduces the overall cost of making each separator.
ContributorsMatsika, Clive (Author) / Jiang, Hanqing (Thesis director) / Phelan, Patrick (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2019-05
Balance of System Cost Analysis to Investigate Future Economic Competitiveness of Tandem Solar Cells
Description
As single junction silicon based solar cells approach their Shockley\u2014Queasier (SQ) conversion efficiency limits, tandem solar cells (TSC) provide an attractive prospect for higher efficiency cells. Although TSCs have been shown to be more efficient, their higher fabrication costs are a limiting factor for their economic competitiveness and large-scale integration in PV power systems. Current literature suggests that even with reduced costs of fabrication in the future, TSCs still offer no competitive benefit for integration in utility-scale systems and may yield minimal benefits only in places where area-related costs are high. This work investigates Balance of Systems (BoS) circumstances under which TSCs can attain economic viability in scenarios where the necessary technological advances are made to increase the efficiency of solar cells beyond the SQ limit.
ContributorsMugwisi, Ngoni (Author) / Holman, Zachary (Thesis director) / Phelan, Patrick (Committee member) / Industrial, Systems (Contributor) / Electrical Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
The goal of this honors thesis creative project was to design, manufacture and test a retrofitted E-bike kit that met certain stated design objections. To design a successful E-bike kit, the needs of the customer were researched and turned into measurable engineering requirements. For the biker, these requirements are speed, range, cost and simplicity. The approach is outlined similarly to the capstone program here at ASU. There is an introduction in sections 1 and 2 which gives the motivation and an overview of the project done. In section 3, the voice of the customer is discussed and converted into requirements. In sections 4, 5,6,7 and 8 the design process is described. Section 4 is the conceptual design where multiple concepts are narrowed down to one design. Section 5 is the preliminary design, where the design parts are specified and optimized to fit requirements. Section 6 is fabrication and assembly which gives details into how the product was manufactured and built. Sections 7 and 8 are the testing and validation sections where tests were carried out to verify that the requirements were met. Sections 9 and 10 were part of the conclusion in which recommendations and the project conclusions are depicted. In general, I produced a successful prototype. Each phase of the design came with its own issues and solutions but in the end a functioning bike was delivered. There were a few design options considered before selecting the final design. The rear-drive friction design was selected based on its price, simplicity and performance. The design was optimized in the preliminary design phase and items were purchased. The purchased items were either placed on the bike directly or had to be manufactured in some way. Once the assembly was completed, testing and validation took place to verify that the design met the requirements. Unfortunately, the prototype did not meet all the requirements. The E-bike had a maximum speed of 14.86 mph and a range of 12.75 miles which were below the performance requirements of 15 mph and 15 miles. The cost was $41.67 over the goal of $300 although the total costs remained under budget. At the end of the project, I delivered a functioning E-bike retrofitting kit on the day of the defense. While it did not meet the requirements fully, there was much room for improvement and optimization within the design.
ContributorsLangerman, Jonathon Henry (Author) / Phelan, Patrick (Thesis director) / Trimble, Steven (Committee member) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
This paper presents an experimental investigation into the effects of altering electrode surface area roughness on thermogalvanic cell performance. A temperature difference between two electrodes was induced and brought to steady state to achieve a difference of around 50 °C, which was maintained with a DC power generated hot wire and a pumped ice bath. The open-circuit voltage values at steady-state were measured by a programed multimeter and the temperatures were measured by a series of type K thermocouples. Electrode surface area roughness was altered using different grit values of sandpaper and measuring the values using a Zescope Optical Profilometer. Once three different surface area average values were achieved, 6 trials were performed with 2 trials per roughness value. The results were tabulated in Section 4 of this report.
It was predicted that increasing the surface area roughness would increase the number of electrons present in the reduction oxidation reaction and decrease the activation resistance of the thermogalvanic system. Decreasing the activation resistance, a component of total internal resistance, would therefore increase the power output of the cell by a small magnitude. The results showed that changing the surface area roughness of the Copper electrodes evidently had no effect on the outputs of the cell system. Additionally, the Seebeck coefficient was also unaffected by the presence of increased surface area roughness.
The work presented in the following paper is part of a continuing effort to better understand the performance of thermogalvanic cells and their heat to electrical energy transfer properties.
It was predicted that increasing the surface area roughness would increase the number of electrons present in the reduction oxidation reaction and decrease the activation resistance of the thermogalvanic system. Decreasing the activation resistance, a component of total internal resistance, would therefore increase the power output of the cell by a small magnitude. The results showed that changing the surface area roughness of the Copper electrodes evidently had no effect on the outputs of the cell system. Additionally, the Seebeck coefficient was also unaffected by the presence of increased surface area roughness.
The work presented in the following paper is part of a continuing effort to better understand the performance of thermogalvanic cells and their heat to electrical energy transfer properties.
ContributorsLopez, Maggie Marie (Author) / Phelan, Patrick (Thesis director) / Miner, Mark (Committee member) / School of Sustainability (Contributor) / School of Music (Contributor) / Mechanical and Aerospace Engineering Program (Contributor, Contributor) / Barrett, The Honors College (Contributor)
Created2017-05
Description
Concentrated Solar Power and Thermal Energy Storage are two technologies that are currently being explored as environmentally friendly methods of energy generation. The two technologies are often combined in an overall system to increase efficiency and reliability of the energy generation system. A collaborative group of researchers from Australia and the United States formed a project to design solar concentrators that utilize Concentrated Solar Power and Thermal Energy Storage. The collaborators from Arizona State designed a Latent Heat Thermal Energy Storage system for the project. It was initially proposed that the system utilize Dowtherm A as the Heat Transfer Fluid and a tin alloy as the storage material. Two thermal reservoirs were designed as part of the system; one reservoir was designed to be maintained at 240˚ C, while the other reservoir was designed to be maintained at 210˚ C. The tin was designed to receive heat from the hot reservoir during a charging cycle and discharge heat to the cold reservoir during a discharge cycle. From simulation, it was estimated that the system would complete a charging cycle in 17.5 minutes and a discharging cycle in 6.667 minutes [1]. After the initial design was fabricated and assembled, the system proved ineffective and did not perform as expected. Leaks occurred within the system under high pressure and the reservoirs could not be heated to the desired temperatures. After adding a flange to one of the reservoirs, it was decided that the system would be run with one reservoir, with water as the Heat Transfer Fluid. The storage material was changed to paraffin wax, because it would achieve phase change at a temperature lower than the boiling point of water. Since only one reservoir was available, charging cycle tests were performed on the system to gain insight on system performance. It was found that the paraffin sample only absorbs 3.29% of the available heat present during a charging cycle. This report discusses the tests performed on the system, the analysis of the data from these tests, the issues with the system that were revealed from the analyses, and potential design changes that would increase the efficiency of the system.
ContributorsKocher, Jordan Daniel (Author) / Wang, Robert (Thesis director) / Phelan, Patrick (Committee member) / Mechanical and Aerospace Engineering Program (Contributor) / Barrett, The Honors College (Contributor)
Created2016-12
Description
In nature, it is commonly observed that animals and birds perform movement-based thermoregulation activities to regulate their body temperatures. For example, flapping of elephant ears or plumage fluffing in birds. Taking inspiration from nature and to explore the possibilities of such heat transfer enhancements, augmentation of heat transfer rates induced by the vibration of solid and well as novel flexible pinned heatsinks were studied in this research project. Enhancement of natural convection has always been very important in improving the performance of the cooling mechanisms. In this research, flexible heatsinks were developed and they were characterized based on natural convection cooling with moderately vibrating conditions. The vibration of heated surfaces such as motor surfaces, condenser surfaces, robotic arms and exoskeletons led to the motivation of the development of heat sinks having flexible fins with an improved heat transfer capacity. The performance of an inflexible, solid copper pin fin heat sink was considered as the baseline, current industry standard for the thermal performance. It is expected to obtain maximum convective heat transfer at the resonance frequency of the flexible pin fins. Current experimental results with fixed input frequency and varying amplitudes indicate that the vibration provides a moderate improvement in convective heat transfer, however, the flexibility of fins had negligible effects.
ContributorsPrabhu, Saurabh (Author) / Rykaczewski, Konrad (Thesis advisor) / Phelan, Patrick (Committee member) / Wang, Robert (Committee member) / Arizona State University (Publisher)
Created2019
Description
humans are currently facing issues with the high level of carbon emissions that will cause global warming and climate change, which worsens the earth’s
environment. Buildings generate nearly 40% of annual global CO2 emissions, of which
28% is from building operations, and 11% from materials and construction. These
emissions must be decreased to protect from further environmental harm. The good news
is there is a way that carbon emissions can be decreased. The use of thermogalvanic
bricks enables electricity generation by the temperature difference between the enclosure
above the ceiling (i.e., the attic in a single-family home) and the living space below. A
ceiling tile prototype was constructed that can make use of this temperature difference to
generate electricity using an electrochemical system called a thermogalvanic cell.
Furthermore, the application of triply periodic minimal surfaces (TPMS) can increase the
thermal resistance of the ceiling tile, which is important for practical applications. Here,
Schwarz P TPMS structures were 3D-printed from polyvinylidene fluoride (PVDF), and
inserted into the electrolyte solution between the electrodes. Graphite was used as
electrodes on the positive and negative sides of the tile, and Iron (II) and Iron (III)
perchlorate salts were used as electrolytes. The maximum generated power was measured
with different porosities of TPMS structure, and one experiment without a TPMS
structure. The results indicated that as the porosity of the TPMS structure increases, the
maximum power decreases. The experiment with no TPMS structure had the largest
maximum power.
ContributorsWen, Chonghan (Author) / Phelan, Patrick (Thesis advisor) / Chen, Candace (Committee member) / Li, Xiangjia (Committee member) / Arizona State University (Publisher)
Created2022