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Design and analysis of smart home energy management system for energy-efficient and demand response operations
Get PDFIn the movie “Iron Man”, Tony Stark, with his highly connected and smart home system, shows the audience an appealing vision of future work and domestic life. Many audiences desire such a living environment where they can not only interact with their homes but also let the homes manage their operation automatically. As technology progressively steps into such a future, realizing a responsive and autonomous smart home is not just a fantasy. To establish grid-interactive homes that help save costs for users and improve grid reliability, this study introduces an energy management framework for smart home environments. This framework provides optimal operation of multiple appliances, taking into account dynamic responses to external factors such as outside weather conditions, homeowner’s preferences, and particularly, gird conditions like time-varying pricing in demand response programs.
As one of the largest energy consumers in the home, the operation of the HVAC system holds great potential for cost savings and energy flexibility—the latter being the ability to adjust its consumption based on grid signals such as time-of-use (TOU) pricing. Achieving cost savings and energy flexibility requires intelligent strategies, one of which is precooling—a control strategy where an air conditioner (AC) cools space when the electricity price is low to avoid expensive operation when the electricity price is high. In previous studies, Model Predictive Control (MPC)-based precooling strategies are typically analyzed through simulations, and field studies in residential buildings are quite limited. In this study, we developed an MPC agent and carried out extensive field tests on nine homes over a period of four months in Oklahoma and Miami. Filed test results show that the MPC agent can reduce energy cost by 28.72%–51.31% on hot summer days and by up to 60.32% on mild summer days, in addition to achieving significant energy flexibility. Moreover, the agent's performance is found to be most impacted by weather conditions, AC performance, user comfort preferences, and floor areas of the homes.
In addition, to further comprehend diverse factors that may impact the results of MPC-based precooling, an EnegyPlus virtual testbed and a corresponding control framework for co-simulation are developed. The purpose of developing such a virtual testbed is to create a simulation environment that enables experiments without the limitation and variability of field tests. The virtual testbed is modified by using the Python script to mimic the on/off cycle in the majority of U.S. residential building HVAC systems. By conducting the sensitivity analysis and ablation study, the MPC-based precooling co-simulation results are evaluated. It was observed in our case study that cost savings achieved through MPC-based precooling were primarily influenced by the use of forecast weather. The accuracy of the models and the prediction horizon of the MPC models also plays a substantial but lesser extent role.
With the optimal operation framework shifting from the HVAC system to multiple appliances, the proposed energy management framework has a broader scope, encompassing not only the HVAC system but also water heaters, non-thermal appliances, and the power flow between photovoltaics panel (PV), batteries, and the grid. Apart from the cost-savings and energy flexibility that can be achieved, the proposed framework also provides a more realistic simulation scenario by considering the user’s appliance time usage preference, water usage, and thermal comfort preferences. Finally, the framework also embedded multi-objective optimization to support the homeowner’s decision-making between cost saving and thermal comfort.
Overall, this study aims to realize the optimal operation of various load-flexible resources under demand response programs in residential buildings. This study investigates the fundamental research for the investigation of methodologies to enhance and understand the interactions between buildings, homeowners, and the grid. Due to the flexibility of the model, this study can be adapted to other residential buildings and even in larger communities
Experimental investigation of elastomer performance for underground hydrogen storage wells
Get PDFThe "Power-to-Gas" concept is vital in the envisaged Hydrogen Economy as it ensures sustainability and energy security. The process involves converting surplus energy from various sources like conventional fossils, wind and solar into hydrogen for storage in underground structures and reproducing them during periods of high energy demand. Depleted hydrocarbon reservoirs are the most common underground structures for hydrogen storage. Being a relatively new concept, Underground Hydrogen Storage (UHS) in depleted hydrocarbon reservoirs is associated with challenges related to several aspects of well integrity, including elastomers as seen in well bore seal assemblies.
This study investigates the behavior of general-purpose oil and gas industry elastomers in UHS environments. Three general-purpose elastomers, Ethylene Propylene Diene Monomer (EPDM), Flouroelastomers (FKM), and Nitrile Butadiene Rubber (NBR), are exposed to varied gas mixtures at different aging conditions via autoclave aging experiments and their physio-mechanical properties examined. In addition, observed cavities on the elastomers are statistically analyzed to ascertain the onset of elastomer failure due to cavity formation. Furthermore, changes in the surface morphology of elastomers due to aging were also investigated via Scanning Electron Microscopy (SEM). The result showed that exposure of elastomers to gaseous hydrogen environments at the specified environmental conditions causes changes in their physio-mechanical properties which may subsequently result in material failure.
Furthermore, two main phenomena were identified to be the primary cause the changes in the mechanical properties of elastomers samples for the given test conditions: Plasticization effect by gases and elastomer chain rupture or cross-linkage formations due to chemical ageing. Carbon dioxide was identified to have the most deteriorative effect on the mechanical properties of elastomers due to its low diffusivity coefficient and high plasticization effect on polymer chains. The effects of pure hydrogen and hydrogen-methane mixtures on the mechanical properties of elastomers were identified to be similar. EPDM showed increased hardness and compressional resistance when aged in 100% hydrogen and hydrogen-methane mix environments at high temperatures and poor compressional resistance at low temperatures. EPDM also maintained its thermal resistance properties in gaseous hydrogen environments. The most significant elastomer degradation in gaseous hydrogen environments was seen in NBR. FKM remained thermally stable in gaseous hydrogen environments, although its compressional resistance reduced at elevated temperatures. Furthermore, SEM showed rougher surfaces of EPDM and NBR elastomers after aging in a pure hydrogen environment at 70oC for 7 days, which was proposed to be due to the formation of cross-links. Also identified on the surface of these elastomers after aging are haphazardly distributed micro-cavities and precipitates proposed to be additives used in material production. Finally, statistical analysis indicated that for all samples aged in 100% H2 and (50% H2 + 50% CH4) for 3 days at 70oC, there is statistical evidence of cavity formation due to aging except for NBR samples aged in 100% H2 at 70oC for 3 days.This thesis has been revised, with changes approved by the Graduate College on June 24, 2023. The original version is available at: https://shareok.org/handle/11244/33756
Impacts of Extratropical Transition on Tropical Cyclone Tornado Occurrence
Get PDFTornadoes that spawn from tropical cyclones (TCs) pose a threat to lives and property. Although nearly half of TCs in the Atlantic Ocean undergo extratropical transition, there has only been one study investigating how tornado occurrence changes during transition. The present study conducts a climatological analysis of the impact of extratropical transition on tornado occurrence in TCs from 1995--2020 by utilizing both observed TC and tornado data as well as radiosonde data. This study divided extratropical transition into three phases: tropical (i.e., pre-transition), transition, and extratropical (i.e., post-transition). The tropical and transition phases have the largest portion and the highest frequencies of tornadoes, whereas the extratropical phase has the fewest and least frequent tornadoes. Analysis of tornado location showed that tornadoes occur increasingly north and east as transition progresses, associated with the recurvature of TCs into the midlatitudes. Further analysis showed that as transition progresses, tornadoes tend to shift farther south within the TC, occur later in the day, and are associated with greater damage. These changes in tornado characteristics are associated with increases in synoptic-scale deep-tropospheric vertical wind shear while TC intensity weakens and the extent of the outer wind field expands. Evaluation of radiosondes showed that the downshear right quadrant of the TC is frequently the most favorable for tornado production, having the highest CAPE, lowest CIN, and highest storm-relative helicity (SRH) values. Throughout transition, CAPE in the downshear right quadrant decreases and CIN has no significant changes. SRH in this quadrant increases at the beginning of transition and decreases following transition. In all quadrants, CAPE tended to decrease as the lower troposphere became cooler and drier throughout transition, although those to the left-of-shear experienced this cooling sooner than right-of-shear. The strengthening of lower-tropospheric vertical wind shear at the beginning of transition results in increases in SRH followed by no significant changes into the extratropical phase. This work is the first comprehensive climatology of TC tornadoes in extratropically transitioning TCs and adds to the current understanding of environmental changes throughout extratropical transition
Effects of non-equilibrium charge carriers on photocatalytic reactions over hybrid plasmonic catalyst
No full textFascinated by how nature can directly transfer solar energy into a chemical reaction, several studies on the photocatalyst have been performed and hoped to imitate nature’s process to achieve similar conversion. Unfortunately, the ultralow efficiencies of the photocatalyst largely remained. Plasmonic catalyst based on the local surface plasmon resonance of noble metal nanoparticles is then investigated to increase the utilization of the visible wavelength and tailor the reaction selectivity toward a more sustainable future. Particularly, the hybrid plasmonic catalyst between noble metal and other components received a lot of interest due to the prolonged lifetime of the charge carriers or the number of chemical reactions that can be activated. However, on the hybrid plasmonic photocatalyst, the mechanism of how non-equilibrium charge carriers induce reactions remains unclear, especially under the solvent effect. In this dissertation, it is attempted to give an understanding of how non-equilibrium electrons can facilitate reactions on the plasmonic hybrid of copper (I) oxide, a promising oxide in photocatalysis using visible light, and of zeolite, a unique micro porous oxide that has several applications in the energy and fuel field. While the former type, the hybrid between plasmonic nanoparticle and the semiconductor, is expected to extend the lifetime of charge carriers, the latter type is applicable to various reactions.
Using CO2 conversion as the probe, we found that the non-equilibrium carriers do not change much the intrinsic activation energy of CO2 dissociation on a Cu2O pristine surface at the excited states compared to the ground state. In contrast, if the oxygen vacancies are introduced, the intrinsic barrier could be reduced at the ground state, and this remaining barrier could be further eliminated at the excited states because of the non-equilibrium electrons. The regeneration of oxygen vacancies is feasible via the hydrogenation process with low required energy and is not affected by the presence of the non-equilibrium charge carriers.
For the hybrid catalyst between a plasmonic metal and zeolite, it is revealed that the non-equilibrium charge carriers can alter the interaction between ammonia and the Lewis acid site of Beta zeolite. The effect is more significant when there are mid-gap states induced Sn or Ti doped into Si-BEA framework. Apart from the effect on the heat adsorption, it is found that if the doped concentration of Ti into zeolite increases, the intrinsic activation energy of the propylene epoxidation also can be reduced due to the higher population of the non-equilibrium electrons to induce reactions. These studies provide the opportunity to use highly energetic charge carriers, generated in plasmonic metal, to tune the zeolite activity for acid-catalyzed reactions.
Finally, we explored the effect of solvent on the excitation energy and found that the H-bond between solvents and reactants could interfere with the interfacial charge transfer process. Notably, the H-bond between solvent and ammonia can prohibit the excitation energy to trigger an electron from the Fermi level to LUMO of ammonia. At the same time, it can reduce the excitation energy to excite an electron from molecular HOMO to the Fermi level. The stronger acidity of the solvent, the more inhibition effect is observed for the transfer of electrons from the Fermi level to LUMO. In addition, we found that the H-bond also affects the HOMO-LUMO gap of the molecules, which directly influences the energy transfer between plasmonic metal and reactants. The findings of this dissertation could be a valuable guideline for hybrid plasmonic catalyst design for sustainable energy and chemical production
The Religious Restructuring of the Politics of Education: Exploring Stalled Support for Education Spending, 1973-2018
No full textRecent research on Americans’ attitudes toward public education focuses on controversial legislation surrounding curriculum, increasing teacher compensation, and changing priorities of political parties. However, the processes by which religion also shapes attitudes toward education remain largely unexplored. Given Robert Wuthnow’s (1988) religious restructuring thesis, which posits religion’s relationship to politics evolved substantially since World War II, sociologists of religion have explored the changing relationship between religion and attitudes toward political institutions. We build upon this body of research, using data from the General Social Survey to explore both religious tradition and religious practice and their associations with attitudes toward education spending from 1973 to 2018. Results show that prior to 1990, attitudes toward education spending have converged across religious traditions. After 1990, this convergence plateaus and remains stable through 2018. Conversely, after 1990, we also capture a divergence across religious practice, with those who report high religious service attendance and report strong religious affiliation showing declining rates of support for educational spending. In a time of heightened political polarization, our findings contribute to our understanding of the changing ways in which religion matters for politics
A mechanistic analysis of particle flow in a multiphase chemical looping reactor with theories of contact mechanics
Get PDFUnderstanding particle dynamics and their characteristics is essential to the operation, design, and optimization of chemical looping reactors. The chemical looping dry reforming (CLDR) process is a novel hydrogen production process in which methane and carbon dioxide mixture is converted into syngas in a cyclic oxidation-reduction reaction in the presence of an oxygen carrier. This paper presents a three-dimensional computational fluid dynamic model to study the fluid flow pattern in a chemical looping dry reforming methane (CLDRM) reactor. The numerical analysis was applied through Eulerian and Lagrangian approaches. This multiphase model design comprises a dual circulating fluidized bed consisting of a high-velocity air reactor (AR) with a high-velocity riser, a cyclone chamber (CC), a fluidizing bed fuel reactor (FR), and a connecting loop, which closes the loop between AR and FR. Analysis of gas-solid hydrodynamics in CLDRM was performed to understand the particles distribution, volume fraction, flow pattern, velocity and circulation between the AR and FR. The evolution of particle flow circulation rate was carefully analyzed to understand the particle material rebalance and the transfer of solid particles between reactors operating on different velocities. The results showed that the CLDR system experiences a pressure imbalance between the reduction and oxidation zones, which causes solid particles to undergo a highly intricate and turbulent pulse flow. This results in periodic bursts of pulses that lead to the intermittent transportation of particles ― in the form of particle clusters― from high-pressure areas to regions with lower pressure. This paper discusses the impacts of velocity and geometric modifications on the distribution of the particles. The results showed that the fluidized beds exhibited a periodic pulse pattern with various phenomena occurring in a millisecond, and it was concluded that an air velocity of 3.2 m/sec, fuel mass flow rate of 0.0025 kg/sec, and connection loop diameter of 25 mm were ideal operating parameters
Perception, visibility, and intervisibility in the late Archaic landscape of the Black Mesa region of Oklahoma, New Mexico, and Colorado
Get PDFPhenomenology, as an interpretive framework centered on perception and life experience, aids archaeologists in understanding past human relationships with landscapes and their features. In the Black Mesa region of Cimarron County, Oklahoma, six enigmatic stone circles may have formed part of a line-of-sight communications network during the late Archaic stage around 3,000 years ago. In all but one instance, the sites are accompanied by a nearby petroglyph feature that suggests some special or ritual significance beyond mere communication. Although it is challenging to craft a coherent narrative of late Archaic life in this transitional region, this study focuses on questions of visibility and intervisibility in order to investigate whether observers at each site could see and be seen by others at different locations (rather than specifically identifying the intended audience of signals emanating from these locations), and how phenomenological and ontological considerations, including language, may have affected Archaic peoples’ perception of their landscape. Distinguishing between seeing, visibility, and perception, I utilize a GIS-based visibility to show that visibility and intervisibility among these stone circles may indeed have been an important consideration to Archaic people in the area
Application of passive seismic interferometry for local and shallow imaging
Get PDFExploratory imaging of the shallow crust is motivated by – (i) the presence of exploitable natural resources, (ii) its influence on seismicity and associated hazards, and (iii) the insights it can provide into the evolution of geological landforms. Keeping in mind these motivations, I use passive seismic interferometry to image the shallow crustal structures. Conventional exploration seismology focuses on local scale imaging using active-source methods (e.g., dynamite, air guns, vibro-seis). In contrast, passive seismic interferometry offers the possibility to use universally available noise sources (both natural and anthropogenic) for subsurface imaging. This approach does not require a spatially and temporally confined seismic source and is thus a cost-effective alternative in logistically challenging environments (e.g., polar ice sheets, exo-planets, etc.). Further, the use of ambient noise as a seismic source minimizes the adverse environmental impact of explosive source experiments in sensitive ecological zones.
Ambient noise methods generally utilize low-frequency diffuse noise fields (e.g., microseisms) for global scale imaging of deep earth structures. Application of these methods at shallow scales is challenged by the scarcity of high-frequency ambient noise sources in local settings. Areas away from anthropological activity have very weak noise sources of sufficiently high frequencies. Although, in urban environments some high-frequency sources are available (e.g., traffic, industrial noise), but these are usually confined to a narrow azimuth. Moreover, local noise sources predominantly produce surface waves which have limited vertical and horizontal resolution to be able to image the shallow subsurface.
In this dissertation, I focus on the applications of passive seismic interferometry for high-resolution imaging of the shallow subsurface (<1 km depth) by attempting to overcome the challenges and limitations mentioned above. Three diverse application scenarios are presented to demonstrate the versatility of the interferometric methods. These include – (i) Passive P- and S-wave reflectivity imaging in an oil field (Wellington, Kansas) setting using reservoir monitoring data; (ii) Passive seismic imaging of a buried alpine valley (Unaweep, Colorado) to test the hypothesis of Paleozoic glaciation; (iii) Passive seismic imaging for seismic hazard assessment in an urban environment (Enid, Oklahoma).
Reflectivity imaging using passive seismic interferometry is generally challenged by the dominance of surface-waves in ambient noise recordings. To overcome this limitation, I develop and implement single-station polarization filters to automatically extract body waves (P- and S-waves) from continuous ambient noise. The extracted waves are then subjected to interferometric processing to retrieve subsurface reflections. This methodology is suitable for sparse and irregular seismic networks such as the previously mentioned reservoir monitoring array. In another application, similar results are achieved by using a teleseismic catalog to extract the P-wave coda.
Road-side deployments in the alpine valley and the urban environment mentioned above make linear array geometry feasible. I take advantage of the linear geometry to interferometrically retrieve surface waves propagating along the array which are then inverted to obtain a shear-velocity profile. I compliment the shear-velocity models with results from other passive seismic methods – e.g., structural reflectivity from teleseismic coda-wave autocorrelation, or layer thickness from horizontal-to-vertical spectral ratio analysis.
The main results presented in this dissertation includes the retrieval of shallow (< 1 km) structural reflections and the estimation of seismic speed ratio (Vp/Vs) at the Wellington Oil field. This is significant since very few studies have reported the retrieval of S-wave reflectivity using passive seismic methods. In the Unaweep canyon, I image the buried valley floor. The undulating sedimentary-basement interface revealed by the passive imaging suggests the glacial genesis of the canyon. In the Enid study, the high lateral resolution near surface model is well correlated with the site amplification data derived from distributed acoustic sensing. In an urban environment, such experiments are relevant for town-planning and can be used to assess the seismic hazard at sub-kilometer scales
Design of Continuity Connections for Precast, Pretensioned Girders Using Ultra-High Performance Concrete
No full textIn recent years, an increased desire to improve the durability and resiliency of bridges has become an important consideration in design. Ultra-high performance concrete (UHPC) is a relatively new cementitious composite material with mechanical and durability properties far superior to conventional concrete. UHPC has high compressive and tensile strength, excellent bond strength to adjacent concrete sections, and a relatively short development length for steel reinforcement. Eliminating joints in a bridge deck with continuous spans can improve the durability of the bridge by reducing the number of pathways for water to penetrate to the bridge structure. The practice of designing connections of precast girders made continuous for live load with conventional concrete is well understood and utilized in practice, but little guidance exists on the structural design of continuity connections made of UHPC or the retrofit of simple spans to be made continuous. The desire to use UHPC is apparent because connections made of conventional concrete often crack during service and the superior properties of UHPC can lead to simpler connection details. Cracking can cause a loss of continuity and allow water to degrade both the reinforcing steel and adjacent concrete. The focus of this research was to investigate how embedment length, UHPC materials, and steel reinforcement geometry affect the performance of connections of pretensioned girders made continuous for live load. A total of six 19 ft long test specimens were constructed to represent a two-span continuous prestressed bridge system. The continuity connections were constructed using two types of UHPC material, a locally developed mix design labeled J3 and a commercially available product. Two types of positive moment steel reinforcement details were tested: 10 in. straight strands and 16 in. long hooked strands, which are both formed as extensions of the prestressing strands in the girders. To replicate the loads a bridge system would experience during service, the specimens were tested to induce both a positive and negative moment in the connection. The measured data correlated well with the literature on the bond strength of UHPC and suggested that hooked strands and longer embedment lengths generally lead to increased load carrying capacity. Additionally, the data suggests that the required dimension and embedment lengths for continuity connections made of UHPC could be smaller than conventional concrete