Engineering Commons^™

Development And Characterization Of Lead & Lead-Free Perovskite Solar Cell Materials, Rubaiya Murshed

UNLV Theses, Dissertations, Professional Papers, and Capstones

In recent years, perovskite photovoltaic technology has offered enormous viability and dimensionality in solar cell research. As a light-harvesting active layer, Perovskite generated remarkable development in device efficiency of 25.7% for the single-junction solar cell, and over 33% for the perovskite/silicon tandem solar cell. Also, perovskite-perovskite tandem solar cell (also called all-perovskite tandem solar cell) shows great potential in device performance and achieved a power conversion efficiency (PCE) of 26.4%. Transitioning photovoltaic technology from the laboratory to commercial products, high PCE, low cost, long lifetime, and low toxicity are some of the critical factors to consider during material selection. Pb-halide …

A One-Dimensional Analysis Of A Microbial Fuel Cell For Efficient Acetate Removal And Power Density Output, David Rouhani

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microbial fuel cells (MFCs) are electrochemical devices that utilize microorganisms to convert organic matter into electrical energy. MFCs have been discussed to have potential application for sustainable wastewater treatment due to their ability to generate electricity while simultaneously treating contaminated water. To optimize MFC performance, numerical models can be used to understand the complex electrochemical and biological processes occurring in the system. In this study, a numerical model was developed to simulate the performance of MFCs under varying operating conditions and to investigate the performance of a MFC for treating wastewater fuel. More specifically, the MFC was modeled to oxidize …

Metastability And Degradation In Cu(In,Ga)Se2 Thin-Film Solar Cells, Mohsen Jahandardoost

UNLV Theses, Dissertations, Professional Papers, and Capstones

Cu(In,Ga)(S,Se)2 or CIGS is a thin-film semiconductor that has shown a device efficiency of 23.35% and 24.2% for single-junction and perovskite/CIGS tandem solar cells, respectively. CIGS offers promising properties such as tunable bandgap and ease of processing making them great candidates for thin-film tandem devices. However, knowledge of the effect of material defects, buffer materials, and post-deposition treatment (PDT) on degradation and metastability behavior in these devices is not well understood.In this dissertation, metastability and long-term degradation of CIGS thin-film solar cells have been investigated under combinatorial stress factors of heat, light, and voltage bias to systematically understand the effect …

Effects Of Distributed Energy Resources On The Bulk Electric System, Stryder Loveday

UNLV Theses, Dissertations, Professional Papers, and Capstones

The traditional power grid was designed with a centralized resource distribution in mind, with a relatively small number of large power generation facilities supplying the vast majority of load. With recent efforts to further diversify the power grid as well as an increased interest in renewable energy sources, there has been an unprecedented amount of new DistributedEnergy Resources (DERs) added to the grid within the last decade. This often heavily influences the local demand where these resources are installed, often causing power to flow in ways not anticipated by the original design of the grid. This thesis reviews the potential …

Dynamic Analysis Of A Microgrid Powered With An Inverter And Machine-Based Distributed Resources, Brandon William Blackstone

UNLV Theses, Dissertations, Professional Papers, and Capstones

The proliferation of renewable distributed energy resources, particularly photovoltaic (PV) power systems, and the increasing need for a reliable power supply has led to the concept of microgrids, a mini-grid that consists of locally connected power generation units and needs, able to operate connected or disconnected from the utility grid, using controlled and coordinated methods to provide for the users of the microgrid the best possible conditions for their needs. The main technical issues facing microgrids include some of the following, seamless transition from stand-alone to utility grid connected operation, how to preserve frequency and voltage stability, and provide the …

Design And Preliminary Evaluation Of A Supercritical Carbon Dioxide Brayton Cycle For Solar Dish Concentrator Clean Energy Production, Danielle Nobles-Lookingbill

UNLV Theses, Dissertations, Professional Papers, and Capstones

As we move toward energy independence and more ambitious clean energy goals, solar energy research must push the efficiency limits of traditional energy generation systems. Increases in efficiency can be achieved by increasing the hot temperature of the power cycle. Recent research demonstrates the potential for increased efficiency and a vastly smaller component size when supercritical carbon dioxide Brayton power cycles are used. Concentrated solar and nuclear heat sources are capable of achieving the high working fluid temperatures needed for significant efficiency gains. This NSF EPSCoR funded, experimental research system is designed to exploit the uniquely immense solar irradiance of …

Stationary Nonimaging Concentrators – A Comprehensive Study And Design Improvements, Srikanth Madala

UNLV Theses, Dissertations, Professional Papers, and Capstones

Most places on our planet receive an annual average radiation between 800-1000 W/m2. In the man-made world, this radiation is largely incident on stationary structures such as buildings, roads, monuments, bridges etc. Moreover, in the natural world also, there are large tracts of barren land which can be put to good use given their solar energy potential. The vision of the current research is to concentrate all this available solar energy to a more readily usable form. Therefore, stationary nonimaging solar concentrator technologies are sought after. This dissertation work is an exhaustive research on the nonimaging concentrating mechanisms with stationary …

Development Of Solar Experiments With Remote Laboratory Capability For Engineering Education Of The Future, Otto Kyle Neidert

UNLV Theses, Dissertations, Professional Papers, and Capstones

Educating future engineers will be handled differently as this modern society has various methods of doing so and a plethora of knowledge to pursue. The availability of computers and internet has changed many things. A subject that is relevant in today’s world but not common to most people and some engineers is solar energy. As part of a grant from the National Science Foundation that was awarded to Louisiana State University (LSU), Florida State University (FSU), and the University of Nevada, Las Vegas (UNLV), the UNLV Center for Energy Research partnered with them to create solar application based learning modules. …

Chemical And Electronic Structure Of Surfaces And Interfaces In Cadmium Telluride Based Photovoltaic Devices, Douglas Arthur Duncan

UNLV Theses, Dissertations, Professional Papers, and Capstones

The surface and interface properties are of the upmost importance in the understanding, optimization, and application for photovoltaic devices. Often the chemical, electronic, and morphological properties of the films are empirically optimized, however when progress slows, a fundamental understanding of these properties can lead to breakthroughs. In this work, surfaces and interfaces of solar cell-relevant films are probed with a repertoire of X-ray analytical and microanalysis techniques including X-ray photoelectron (XPS), X-ray excited Auger electron (XAES), X-ray emission (XES) spectroscopies, and atomic force (AFM) and scanning electron (SEM) microscopies.

Silicon-based devices currently dominate the solar market, which is rather inflexible …

Designing, Building And Testing A Solar Thermoelectric Generation, Steg, For Energy Delivery To Remote Residential Areas In Developing Regions, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

New alternatives and inventive renewable energy techniques which encompass both generation and power management solutions are fundamental for meeting remote residential energy supply and demand today, especially if the grid is quasi-inexistent. Solar thermoelectric generators can be a cost-effective alternative to photovoltaics for a remote residential household power supply. A complete solar thermoelectric energy harvesting system is presented for energy delivery to remote residential areas in developing regions. To this end, the entire system was built, modeled, and then validated with LTspice simulator software via thermal-to-electrical analogy schemes. Valuable data in conjunction with two novel LTspice circuits were obtained, showing …

Spectroscopic Investigation Of The Chemical And Electronic Properties Of Chalcogenide Materials For Thin-Film Optoelectronic Devices, Kimberly Horsley

UNLV Theses, Dissertations, Professional Papers, and Capstones

Chalcogen-based materials are at the forefront of technologies for sustainable energy production. This progress has come only from decades of research, and further investigation is needed to continue improvement of these materials.

For this dissertation, a number of chalcogenide systems were studied, which have applications in optoelectronic devices, such as LEDs and Photovoltaics. The systems studied include Cu(In,Ga)Se2 (CIGSe) and CuInSe2 (CISe) thin-film absorbers, CdTe-based photovoltaic structures, and CdTe-ZnO nanocomposite materials. For each project, a sample set was prepared through collaboration with outside institutions, and a suite of spectroscopy techniques was employed to answer specific questions about the system. These …

Development Of A Black-Box Transient Thermal Model For Residential Buildings, Andrew Cross

UNLV Theses, Dissertations, Professional Papers, and Capstones

Heavily populated metropolitan areas located in cooling-dominated climates, as are found in the Desert Southwest, pose a challenge to electrical utilities that service these areas. During the late afternoons of the summer months, residents of these metropolitan areas require larger than normal amounts of power to run their homes' air conditioning systems, at significant expense to the utilities. In the study reported here, interior temperature and power consumption data, accumulated over the course of a year and a half from seven houses within a Las Vegas neighborhood, are used to develop a predictive black-box statistical model for residential thermal transience. …

Power Optimization, Diagnostic Monitoring, And Modeling Of Photovoltaic System, Khalid Hurayb

UNLV Theses, Dissertations, Professional Papers, and Capstones

Photovoltaic (PV) solar energy has been sustaining a major growth rate over the last decade in many parts of the world. This steep growth has been driven by concern about climate change, the adoption of renewable portfolio standards, government incentives, and reduction in PV system costs. Recently, however, such large PV penetration into the electrical grid is cause a concern that might curb such a growth; namely, the incontrollable intermittency of power generated on cloudy days. Furthermore, conventional PV system configurations often do not harness the maximum power that is available under partial shading caused by clouds or shadows of …

Study Of Water Transport Phenomena On Cathode Of Pemfcs Using Monte Carlo Simulation, Karn Soontrapa

UNLV Theses, Dissertations, Professional Papers, and Capstones

This dissertation deals with the development of a three-dimensional computational model of water transport phenomena in the cathode catalyst layer (CCL) of PEMFCs. The catalyst layer in the numerical simulation was developed using the optimized sphere packing algorithm. The optimization technique named the adaptive random search technique (ARSET) was employed in this packing algorithm. The ARSET algorithm will generate the initial location of spheres and allow them to move in the random direction with the variable moving distance, randomly selected from the sampling range, based on the Lennard-jones potential of the current and new configuration. The solid fraction values obtained …

Post-Occupancy Energy Efficiency Evaluation Of A Leed Platinum Federal Government Facility, Theresa Tincher

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study was to gain a comprehensive understanding of the Leadership in Energy and Environmental Design (LEED®) certification system and its relevance to Federal policies, building codes, and building standards, develop experience with whole building energy modeling, and determine the actual post-occupancy energy usage as compared with developed model and design projections. This thesis hypothesized the U.S. Green Building Council's LEED rating system compared favorably to other policies, codes, and standards in use at the time, and the U.S. Bureau of Reclamations' LEED Platinum Lower Colorado Regional Office Green Building (LCROGB), located in Boulder City, Nevada, operated …

Criticality And Characteristic Neutronic Analysis Of A Transient-State Shockwave In A Pulsed Spherical Gaseous Uranium-Hexafluoride Reactor, Jeremiah Boles

UNLV Theses, Dissertations, Professional Papers, and Capstones

The purpose of this study is to analyze the theoretical criticality of a spherical uranium-hexafluoride reactor with a transient, pulsed shockwave emanating from the center of the sphere in an outward-radial direction. This novel nuclear reactor design, based upon pulsed fission in a spherical enclosure is proposed for possible use in direct energy conversion, where the energy from fission products is captured through the use of electrostatic fields or through induction. An analysis of the dynamic behavior of the shockwave in this reactor is the subject of this thesis. As a shockwave travels through a fluid medium, the characteristics of …

Investigation Of Peak Load Reduction Strategies In Residential Buildings In Cooling Dominated Climates, Fady Atallah

UNLV Theses, Dissertations, Professional Papers, and Capstones

This investigation of peak load reduction strategies in residential buildings contributes to the global international efforts in reducing energy consumption and is related directly to energy efficiency in residential and commercial buildings. Work reported here involves computer aided building energy simulation of energy efficient and non-energy efficient residential homes coupled with empirical energy consumption data gathered from monitoring an array of energy efficient residential homes. The latter have been implemented for peak load reduction strategies. In addition non-energy efficient residential homes have been monitored to compare performance to the energy efficient homes. This study demonstrates the crucial importance of energy …

Predicting The Performance Of A Solar Domestic Water Heating System With Evacuated Tube Collectors And Hydronic Radiant Flooring, Kimberly Nicole Hammer

UNLV Theses, Dissertations, Professional Papers, and Capstones

Residential solar thermal system installations have been significantly increasing in the last decade and there exists limited resources for reasonably predicting the performance of those systems. A simulated model is developed in MATLAB® and used to predict the performance of a solar domestic water heating system. In the simulated system, hot water is generated using evacuated tube solar collectors and stored in a domestic hot water storage tank, which utilizes immersed coil heat exchangers. The system is designed to provide hydronic radiant floor heating to its occupants based on the heat loss of a building energy model for an energy-efficient …

Investigating The Feasibility Of Growing Algae For Fuel In Southern Nevada, Faegheh Moazeni

UNLV Theses, Dissertations, Professional Papers, and Capstones

Microalgae capable of growing in waste are adequate to be mass-cultivated for biodiesel, avoiding fertilizers and clean water, two obstacles to sustainability of the feedstock production. This study replaces fertilizers and clean water with waste products. The investigated wastes include (1) the liquid fraction of sewage after solids and particles are removed, known as centrate, and (2) algal biomass residue, i.e. the algae remaining at the end of the lipids extraction process at biofuel plants. These wastes contain sufficient amount of nitrogen and phosphorus required for algal growth. This study proposes a system in which centrate would be used as …

Investigating The Impacts Of Conventional And Advanced Treatment Technologies On Energy Consumption At Satellite Water Reuse Plants, Jonathan Roy Bailey

UNLV Theses, Dissertations, Professional Papers, and Capstones

With the ever increasing world population and the resulting increase in industrialization and agricultural practices, depletion of two of the world's most important natural resources, water and fossil fuels, is inevitable. Water reclamation and reuse is the key to protecting these natural resources. Water reclamation using smaller decentralized wastewater treatment plants, known as satellite water reuse plants (WRP), have become popular in the last decade. With stricter standards and regulations on effluent quality and requirements for a smaller land footprint (i.e. real estate area), additional treatment processes and advanced technologies are needed. This greatly increases the energy consumption of an …

Comparison And Simulation Of Salt-Ceramic Composites For Use In High Temperature Concentrated Solar Power, Lauren Michelle Fossile

UNLV Theses, Dissertations, Professional Papers, and Capstones

Due to the inherently intermittent nature of solar energy caused by cloud cover among other sources, thermal storage systems are needed to make solar energy more consistent. This same technology could be used to prolong the daily number of useful hours of solar energy power plants. Salt-ceramic materials are a relatively new prospect for heat storage, but have been researched mostly with magnesium oxide and several different carbonate salts. Salt ceramics are a phase change material where the salt changes phase inside the ceramic structure allowing for the system to use the sensible heat of both materials and the latent …

Effects Of Moisture Augmentation Of Municipal Solid Waste Through Addition Of Food Waste Or Wastewater Treatment Biosolids On Bio-Gas Formation For Power Generation, Jared Michael Gore

UNLV Theses, Dissertations, Professional Papers, and Capstones

An investigation into the effect of moisture augmentation by manipulation of food waste proportion or wastewater treatment plant biosolids proportion was undertaken to determine the effects on production of methane and other biogases from municipal solid waste (MSW). Laboratory microcosm experiments were performed to determine the effect of various proportions of influent waste streams on the production of biogas. Results indicated that moisture augmentation through the addition of food waste to MSW increases the overall bio-gas and hydrogen gas formed during fermentation. Moisture augmentation through addition of wastewater treatment bio-solids lead to inconclusive results. Addition of food waste to MSW …

Improving Efficiency And Capacity Of Hydro-Turbines In The Western United States, Hoover Dam, Jonathan Sanchez

UNLV Theses, Dissertations, Professional Papers, and Capstones

The goal for this thesis is to minimize clearances and tolerances, in order to prevent water leakage. A proper seal on the seal rings does not let excess water flow through the turbine runner, thus conserving more water and wasting less energy. Moreover, water leakage past worn wear plates allows for an extra load for the turbine when operating in condense mode. When the wicket gates are closed, water leakage past worn plates wastes mechanical energy in the water; thus, decreasing the efficiency of the Francis turbine, especially when operating at partial loads. Furthermore, the wicket gates also known as …

Evaluation Of Highly Efficient Distribution Transformer Design And Energy Standards Based On Load, James Sanguinetti

UNLV Theses, Dissertations, Professional Papers, and Capstones

Power distribution transformers have been prevalent in commercial building distribution systems since the inception of modern commercial electricity. Yet as more and more manufactures seek to improve transformer efficiencies by making changes to the design of the transformer itself, a fundamental concept may be overlooked - the impact transformer demand sizing has on power losses. When modern transformers are improperly sized for the application they will be installed for they are not being utilized at their optimum design loading range, which may impact operating efficiency.

This thesis will aim to test and evaluate modern day transformer design coupled with currently …

Buffering Pv Output During Cloud Transients With Energy Storage, Yacouba Moumouni

UNLV Theses, Dissertations, Professional Papers, and Capstones

Consideration of the use of the major types of energy storage is attempted in this thesis in order to mitigate the effects of power output transients associated with grid-tied CPV systems due to fast-moving cloud coverage. The approach presented here is to buffer intermittency of CPV output power with an energy storage device (used batteries) purchased cheaply from EV owners or battery leasers. When the CPV is connected to the grid with the proper energy storage, the main goal is to smooth out the intermittent solar power and fluctuant load of the grid with a convenient control strategy. This thesis …

Dynamic Modelling Of Single Phase Grid Connected Photovoltaic System, Gopi Krishna Ari

UNLV Theses, Dissertations, Professional Papers, and Capstones

Grid-connected photovoltaic (PV) power systems have been sustaining an exponential growth rate during the past decade. This steep growth is driven by a growing concern about climate change, the adoption of an aggressive regional renewable portfolio standard, rebates and tax incentives, and reduction in PV system cost. One of the main technical barriers that can ultimately limit further PV penetration is the fast variations in the PV system's output power induced by cloud transients. Such events are known to cause voltage fluctuations which may lead to excessive operations of voltage regulation equipment and light flickering.

Solar irradiance variability, which can …

Modeling Passive Solar Distillation Production In Las Vegas, Nevada, Noe I. Santos

UNLV Theses, Dissertations, Professional Papers, and Capstones

A study has been performed to examine the effects of daily weather on the performance of commercial solar distillation basins (solar stills). The objectives of this study were to evaluate the long term performance of solar stills, to instrument two solar stills and record sub-hourly thermal properties, to evaluate existing heat transfer modeling methods for hourly production, and to create new models to predict daily production using experimental distillate production and local weather data by utilizing artificial neural networks, genetic algorithms, and multivariate regression. A system dynamics model was also created to determine the required basin area and storage volume …

Direct Contact Pyrolysis Of Hydrocarbons: A Source Of Hydrogen And Interesting Carbon Formations, Peter G. Faught

UNLV Theses, Dissertations, Professional Papers, and Capstones

The work detailed in this document looks at a novel liquid metal supported catalytic system for the generation of hydrogen by decomposition of ethanol through direct contact pyrolysis. The hydrogen is produced at relatively low temperatures (500-600°C) and has carbon and water as co-products. It should be noted that CO is not observed as a product at these low temperatures. This is to be contrasted with the hydrogen produced at higher temperature from ethanol which does contain carbon monoxide. The presence of carbon monoxide in hydrogen complicates fuel cell operation and catalytic chemical processes. Thus, the lack of CO in …

Energy-Based Analysis Of Utility Scale Hybrid Power Systems, Kwame Agyenim-Boateng

UNLV Theses, Dissertations, Professional Papers, and Capstones

The promise of large-scale use of renewables such as wind and solar for supplying electrical power is tempered by the sources' transient behavior and the impact this would have on the operation of the grid. Among the methods cited for addressing some of those concerns are exploring the complementary nature of solar and wind power generation, and through the use of supplemental energy storage. While the technology for the latter has not been proven to be economical on a large scale at the present time, some assessments of what magnitude is required can be made. An energy-based analysis of utility …

Modeling Of A Novel Solar Down Beam Test Facility Utilizing Newtonian Optics, Ryan J. Hoffmann

UNLV Theses, Dissertations, Professional Papers, and Capstones

As advances in concentrated solar energy progress there will inevitably be an increase in the demand of resources for testing new conceptions. Currently, there are limited facilities available for taking concentrated solar energy concepts from the laboratory bench scale to the engineering test scale. A proposed solution is a scientific and developmental facility that provides highly concentrated solar energy at ground level. The design presented is a solar down beam test facility utilizing a Newtonian optics approach with a flat rectangular down beam mirror to reflect and concentrate the sun's rays at ground level.

Literature review suggests a hyperbolic reflector …