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- Genre: Masters Thesis
- Creators: Huang, Huei-Ping
Description
Rooftop photovoltaic (PV) systems are becoming increasingly common as the efficiency of solar panels increase, the cost decreases, and worries about climate change increase and become increasingly prevalent. An under explored aspect of rooftop solar systems is the thermal effects that the systems have on the local area. These effects are investigated in this paper to determine the overall impact that solar systems have on the heating and cooling demands of a building as well as on the efficiency losses of the solar panels due to the increased temperature on the panels themselves. The specific building studied in this paper is the Goldwater Center for Science and Engineering located in the Tempe campus of Arizona State University. The ambient conditions were modeled from a typical July day in Tempe. A numerical model of a simple flat roof was also created to find the average rooftop temperature throughout the day. Through this study it was determined that solar panels cause a decrease in the maximum temperature of the rooftop during the day, while reducing the ability of the roof to be cooled during the night. The solar panels also saw a high temperature during the day during the most productive time of day for solar panels, which saw a decrease in total energy production for the panels.
ContributorsNaber, Nicholas (Author) / Huang, Huei-Ping (Thesis advisor) / Phelan, Patrick (Committee member) / Bocanegra, Luis (Committee member) / Arizona State University (Publisher)
Created2022
Description
Computing the fluid phase interfaces in multiphase flow is a challenging area of research in fluids. The Volume of Fluid andLevel Set methods are a few algorithms that have been developed for reconstructing the multiphase fluid flow interfaces.
The thesis work focuses on exploring the ability of neural networks to reconstruct the multiphase fluid flow interfaces using
a data-driven approach.
The neural network model has liquid volume fraction stencils as an input, and it predicts the radius of the circle as an
output of the network which represents a phase interface separating two immiscible fluids inside a fluid domain. The liquid
volume fraction stencils are generated for randomly varying circle radii within a 1x1 domain using an open-source VOFI
library. These datasets are used to train the neural network. Once the model is trained, the predicted circular phase
interface from the neural network output is used to generate back the predicted liquid volume fraction stencils.
Error norms values are calculated to assess the error in the neural network model’s predicted liquid volume fraction
stencils with the actual liquid volume fraction stencils from the VOFI library. The neural network parameters are optimized
by testing them for different hyper-parameters to reduce the error norms. So as to minimize the difference between the
predicted and the actual liquid volume fraction stencils and errors in reconstructing the fluid phase interface geometry.
ContributorsPawar, Pranav Rajesh (Author) / Herrmann, Marcus (Thesis advisor) / Zhuang, Houlong (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2023
Description
The energy consumed by buildings occupies a large part of energy consumption and carbon emissions. Meanwhile, enormous amounts of waste heat from buildings and the swiftly increasing demand for electric energy have become one of the essential contradictions that scientists pay attention to. As a result, how to make use of the waste heat to generate electric energy becomes an appreciable research topic. In the latest research, it is common to convert the thermal energy generated by the temperature difference into electrical energy using the Seebeck effect. In previous research, a prototype of a thermogalvanic cell with graphite as the electrodes and a combination of Iron (II) and Iron (III) perchlorate salts (Fe(ClO4)2, Fe(ClO4)3) as the electrolyte, and with a 3D-printed Schwarz-P structure, was designed and assembled for achieving the energy conversion. The research shows that the incorporation of a 3D-printed Schwarz-P structure improves the thermogalvanic cell’s performance and increases the temperature difference across the cell. Here we focus on the same type of thermogalvanic cell prototype and keep the same working temperature difference but use different electrolyte concentrations (0.05, 0.10, 0.15, 0.20, and 0.25 mol/L) to measure the electric output, including open-circuit voltage, short-circuit current, and maximum output power, and the internal resistance. The results indicate that the open-circuit voltage and maximum output power increase with the rise of electrolyte concentrations, and the short-circuit current decreases with the rise of electrolyte concentrations.
ContributorsHan, Xiaochuan (Author) / Phelan, Patric (Thesis advisor) / Huang, Huei-Ping (Committee member) / Bocanegra, Luis (Committee member) / Arizona State University (Publisher)
Created2022
Description
This thesis aims to determine how finite wing aerodynamic loads change in proximity to the ground. In this study, the primary design tool is an inviscid panel method code, VORLAX.
The validation tool is a commercial volume grid CFD package, ANSYS FLUENT. I use VORLAX
to simulate wings with different incidences and aspect ratios to look at how ground effect
impacts spanwise loading and incipient flow separation. Then the results were compared to
widely published equations such as McCormick, Torenbeek, and Hoerner & Borst. Because I
found that these “famous” equations function best only for specific conditions, I propose a
new empirical equation to estimate ground effect lift as a function of aspect ratio and
incidence. Using Stratford’s method to predict signs of flow separation in the inviscid
solutions, I found that variations in the height above the ground were not significant enough
to change the stall angle of low aspect ratio wings. I did find early signs of flow separation
with increasing aspect ratio. I observe significant changes in spanwise loading when in
ground effect; as I narrow the gap, the transverse loading builds higher near the center of the
wing. These effects were more apparent in wings with smaller aspect ratio; higher aspect
ratio wings experience a higher loading gradient near the tips in proximity to the ground. I
found that high aspect ratio wings have a smaller stall angle compared to that of lower
aspect ratio wings; these trends are consistent between the potential flow solution and the
volume grid CFD viscous solution.
ContributorsValenzuela, Jose Vanir (Author) / Takahashi, Timothy (Thesis advisor) / Dahm, Werner (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2024
Description
Multiphase flows are relevant to various industrial processes and are also a ubiquitous feature of nature. Atomization is a Gas-Liquid class of multiphase flow in which the liquid bulk disintegrates into a spectrum of drops. The final drop size distribution of fragmenting liquids is important and is crucial to quantifying the performance of atomizers. This thesis implements two models of ligament breakup. The first model provides a method to determine the droplet size distribution of fragmenting ligaments. The second model provides a relation between ligament stretching, aspect ratio and dimensionless properties like Ohnesorge and Weber numbers for ligaments being stretched by aerodynamic force. The first model by Villermaux et.al considers a ligament as a linear succession of liquid blobs which undergo continuous interplay during destabilization. The evolution of their size distribution ultimately rules the droplet size distribution which follow a gamma distribution [14]. The results show that the Direct Numerical Simulations (DNS) of ligaments with different perturbations fragmented into very few drops and cannot be used to confirm that they follow the predicted gamma distribution. The second model considers a ligament breakup due to Rayleigh-Plateau Instability and provides an equation for ligament stretching. Through test runs the proportionality constant in the equation is determined by a least square fit. The theoretical number of drops is compared with the number of drops resulting from the Direct Numerical Simulation of ligament with a sinusoidal perturbation. It is found that the wavelength of the initial perturbation does not determine the number of drops obtained by ligament breakup
ContributorsRama Krishna, Prathyush (Author) / Herrmann, Marcus (Thesis advisor) / Takahashi, Timothy (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2021
Description
Adsorption equilibrium is an important metric used to assess adsorbent performance for gas mixture separation processes. Gas adsorption processes such as carbon capture are becoming more urgent as climate change and global warming accelerate. To speed up and reduce the cost of research on adsorbent materials and adsorption processes, I developed an open-source Python code that generates mixed gas adsorption equilibrium data using pure gas adsorption isotherms based on the ideal adsorbed solution theory (IAST). The major efforts of this M.S. research were placed on adding additional components to the mixture models since most other publications focused on binary gas mixtures. Generated mixed-gas equilibrium data were compared to experimentally collected data in order to validate the multicomponent IAST model and to determine the accuracy of the computer codes developed in this work. Additional mixed-gas equilibrium data were then generated and analyzed for trends in the data for humid flue gas conditions, natural gas processing conditions, and hydrogen gas purification conditions. For humid flue gas conditions, neither the analyzed Mg-MOF-74 nor the Zeolite 13X were shown to be suitable for use. For natural gas processing conditions, the Zeolite 13X was determined to be a much better candidate for use than the MIL-101. For hydrogen gas purification conditions, the Zeolite 5A was determined to be a better adsorbent for use than CD-AC due to the Zeolite 5A’s much lower adsorption of H2.
ContributorsCiha, Trevor (Author) / Deng, Shuguang (Thesis advisor) / Machas, Michael (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2022
Quantum Mechanical Study of the Electronic Structure and Thermoelectric Properties of Heusler Alloys
Description
Heusler alloys were discovered in 1903, and materials with half-metallic characteristics have drawn more attention from researchers since the advances in semiconductor industry [1]. Heusler alloys have found application as spin-filters, tunnel junctions or giant magnetoresistance (GMR) devices in technological applications [1]. In this work, the electronic structures, phonon dispersion, thermal properties, and electrical conductivities of PdMnSn and six novel alloys (AuCrSn, AuMnGe, Au2MnSn, Cu2NiGe, Pd2NiGe and Pt2CoSn) along with their magnetic moments are studied using ab initio calculations to understand the roots of half-metallicity in these alloys of Heusler family. From the phonon dispersion, the thermodynamic stability of the alloys in their respective phases is assessed. Phonon modes were also used to further understand the electrical transport in the crystals of these seven alloys. This study evaluates the relationship between materials' electrical conductivity and minority-spin bandgap in the band structure, and it provides suggestions for selecting constituent elements when designing new half-metallic Heusler alloys of C1b and L21 structures.
ContributorsPatel, Deep (Author) / Zhuang, Houlong (Thesis advisor) / Solanki, Kiran (Committee member) / Huang, Huei-Ping (Committee member) / Arizona State University (Publisher)
Created2023
Description
A numerical study of incremental spin-up and spin-up from rest of a thermally- stratified fluid enclosed within a right circular cylinder with rigid bottom and side walls and stress-free upper surface is presented. Thermally stratified spin-up is a typical example of baroclinity, which is initiated by a sudden increase in rotation rate and the tilting of isotherms gives rise to baroclinic source of vorticity. Research by (Smirnov et al. [2010a]) showed the differences in evolution of instabilities when Dirichlet and Neumann thermal boundary conditions were applied at top and bottom walls. Study of parametric variations carried out in this dissertation confirmed the instability patterns observed by them for given aspect ratio and Rossby number values greater than 0.5. Also results reveal that flow maintained axisymmetry and stability for short aspect ratio containers independent of amount of rotational increment imparted. Investigation on vorticity components provides framework for baroclinic vorticity feedback mechanism which plays important role in delayed rise of instabilities when Dirichlet thermal Boundary Conditions are applied.
ContributorsKher, Aditya Deepak (Author) / Chen, Kangping (Thesis advisor) / Huang, Huei-Ping (Committee member) / Herrmann, Marcus (Committee member) / Arizona State University (Publisher)
Created2011
Description
Image processing in canals, rivers and other bodies of water has been a very important concern. This research using Image Processing was performed to obtain a photographic evidence of the data of the site which helps in monitoring the conditions of the water body and the surroundings. Images are captured using a digital camera and the images are stored onto a datalogger, these images are retrieved using a cellular/ satellite modem. A MATLAB program was designed to obtain the level of water by just entering the file name into to the program, a curve fit model was created to determine the contrast parameters. The contrast parameters were obtained using the data obtained from the gray scale image mainly the mean and variance of the intensity values. The enhanced images are used to determine the level of water by taking pixel intensity plots along the region of interest. The level of water obtained is accurate to less than 2% of the actual level of water observed from the image. High speed imaging in micro channels have various application in industrial field, medical field etc. In medical field it is tested by using blood samples. The experimental procedure proposed determines the flow duration and the defects observed in these channel using a fluid introduced into the micro channel the fluid being water based dye and whole milk. The viscosity of the fluid shows different types of flow patterns and defects in the micro channel. The defects observed vary from a small effect to the flow pattern to an extreme defect in the channel such as obstruction of flow or deformation in the channel. The sample needs to be further analyzed by SEM to get a better insight on the defects.
ContributorsShasedhara, Abhijeet Bangalore (Author) / Lee, Taewoo (Thesis advisor) / Huang, Huei-Ping (Committee member) / Chen, Kangping (Committee member) / Arizona State University (Publisher)
Created2011
Description
The evolution of single hairpin vortices and multiple interacting hairpin vortices are studied in direct numerical simulations of channel flow at Re-tau=395. The purpose of this study is to observe the effects of increased Reynolds number and varying initial conditions on the growth of hairpins and the conditions under which single hairpins autogenerate hairpin packets. The hairpin vortices are believed to provide a unified picture of wall turbulence and play an important role in the production of Reynolds shear stress which is directly related to turbulent drag. The structures of the initial three-dimensional vortices are extracted from the two-point spatial correlation of the fully turbulent direct numerical simulation of the velocity field by linear stochastic estimation and embedded in a mean flow having the profile of the fully turbulent flow. The Reynolds number of the present simulation is more than twice that of the Re-tau=180 flow from earlier literature and the conditional events used to define the stochastically estimated single vortex initial conditions include a number of new types of events such as quasi-streamwise vorticity and Q4 events. The effects of parameters like strength, asymmetry and position are evaluated and compared with existing results in the literature. This study then attempts to answer questions concerning how vortex mergers produce larger scale structures, a process that may contribute to the growth of length scale with increasing distance from the wall in turbulent wall flows. Multiple vortex interactions are studied in detail.
ContributorsParthasarathy, Praveen Kumar (Author) / Adrian, Ronald (Thesis advisor) / Huang, Huei-Ping (Committee member) / Herrmann, Marcus (Committee member) / Arizona State University (Publisher)
Created2011