Mechanical Engineering Commons^™

Molecular Dynamics Study Of Thermal Conductivity Enhancement Of Water Based Nanofluids, Parveen Sachdeva

Electronic Theses and Dissertations

A systematic investigation using molecular dynamics (MD) simulation involving particle volume fraction, size, wettability and system temperature is performed and the effect of these parameters on the thermal conductivity of water based nanofluids is discussed. Nanofluids are a colloidal suspension of 10 -100 nm particles in base fluid. In the last decade, significant research has been done in nanofluids, and thermal conductivity increases in double digits were reported in the literature. This anomalous increase in thermal conductivity cannot be explained by classical theories like Maxwell's model and Hamilton-Crosser model for nanoparticle suspensions. Various mechanisms responsible for thermal conductivity enhancement in …

Effect Of Sodium And Absorber Thickness On Cigs2 Thin Film Solar Cells, Parag Vasekar

Electronic Theses and Dissertations

Chalcopyrites are important contenders among solar cell technologies due to direct band gap and higher absorption coefficient. CuIn1-xGaxS2 (CIGS2) thin-film solar cells are of interest for space power applications because of near optimum bandgap of 1.5 eV for AM0 solar radiation outside the earth's atmosphere. The record efficiency of 11.99% has been achieved on a 2.7 µm CIGS2 thin film prepared by sulfurization at FSEC PV Materials Laboratory. Since CIGS2 films are typically grown in copper-rich regime, excess cuprous sulfide which helps in the formation of CIGS2 is etched away. This makes CIGS2 nearly stoichiometric. However, it is difficult to …

Numerical Solution Of The Two-Phase Incompressible Navier-Stokes Equations Using A Gpu-Accelerated Meshless Method, Jesse Kelly

HIM 1990-2015

This project presents the development and implementation of a GPU-accelerated meshless two-phase incompressible fluid flow solver. The solver uses a variant of the Generalized Finite Difference Meshless Method presented by Gerace et al. [1]. The Level Set Method [2] is used for capturing the fluid interface. The Compute Unified Device Architecture (CUDA) language for general-purpose computing on the graphics-processing-unit is used to implement the GPU-accelerated portions of the solver. CUDA allows the programmer to take advantage of the massive parallelism offered by the GPU at a cost that is significantly lower than other parallel computing options. Through the combined use …

Integrated Servomechanism And Process Control For Machining Processes, Yan Tang

Electronic Theses and Dissertations

In this research, the integration of the servomechanism control and process control for machining processes has been studied. As enabling strategies for next generation quality control, process monitoring and open architecture machine tools will be implemented on production floor. This trend brings a new method to implement control algorithm in machining processes. Instead of using separate modules for servomechanism control and process control individually, the integrated controller is proposed in this research to simultaneously achieve goals in servomechanism level and the process level. This research is motivated by the benefits brought by the integration of servomechanism control and process control. …

Stress Intensity Factor Dependence Of Hg-Al Liquid Metal Embrittlement, Scott Keller

Electronic Theses and Dissertations

When high strength aluminum alloys are subjected to liquid metals, physical and chemical reactions ensue resulting in what is known as liquid metal embrittlement (LME). A subset of environmentally-assisted cracking, LME is exhibited when a liquid metal, e.g. Hg or Ga, comes into intimate contact with a solid metal having significant susceptibility. As mechanical loads are applied, the interaction between the two metals results in a reduction in the flow properties of the solid metal. Several theories have been proposed to identify the underlying microstructural failure mechanism; however, none have been widely accepted, as failures can typically incorporate features common …

Pressure Drop And Endwall Heat Transfer Effects Of Porous Turbulators In A Rectangular Channel, Jared Pent

Electronic Theses and Dissertations

This study examines the local and averaged endwall heat transfer effects of a staggered array of porous pin fins within a rectangular channel. The porous pin fins were made from aluminum and had a pore density of 10 pores per inch (PPI). The pressure drop through the channel was also determined for several flow rates and presented in terms of the friction factor. Local heat transfer coefficients on the endwall were measured using Thermochromic Liquid Crystal (TLC) sheets recorded with a charge-coupled device (CCD) camera. Static and total pressure measurements were taken at the entrance and exit of the test …

The Effect Of Heat Transfer Coefficient On High Aspect Ratio Channel Accompanied By Varying Rib Aspect Ratio, An Le

Electronic Theses and Dissertations

Heat transfer and pressure data were performed and reported on two different rigs. The first rig has an aspect ratio of (19:1) with two different inlet conditions and the second rig is composed of two different aspect ratio channels, (1:8) and (1:4). Rib turbulators were used as a flow disruptor scheme to enhance the heat transfer and friction factor. Rib aspect ratios ranging from (1:1) to (1:5) rib-height-to-width ratio were used. The first channel rib-width-to-pitch (Wr/P) ratio was kept at 1/2 where flow was kept at relatively low Reynolds numbers, between 3000 and 13000. Results from the current tests showed …

Design Of Sea Water Heat Exchanger For Miniature Vapor Compression Cycle, James Hughes

Electronic Theses and Dissertations

Recent advances in the development of miniature vapor compression cycle components have created unique opportunities for heating and cooling applications, specifically to human physiological requirements that arise in extreme environments. Diving in very cold water between 1.7 and 5°C requires active heating because passive thermal insulation has proven inadequate for long durations. To maintain diver mobility and cognitive performance, it is desirable to provide 250 to 300 W of heat from an untethered power source. The use of a miniature vapor compression cycle reduces the amount of power (batteries or fuel cell) that the diver must carry by 2.5 times …

Droplet Flows In Microchannels Using Lattice Boltzmann Method, Amit Gupta

Electronic Theses and Dissertations

Microelectromechanical systems (MEMS) have widespread applications in medical, electronical and mechanical devices. These devices are characterized by the smallest dimension which is at least one micrometer and utmost one millimeter. Rapid progress in the manufacture and utilization of these microdevices has been achieved in the last decade. Current manufacturing techniques of such devices and channels include surface silicon micromachining; bulk silicon micromachining; lithography; electrodeposition and plastic molding; and electrodischarge machining (EDM). In recent years, electrostatic, magnetic, electromagnetic and thermal actuators, valves, gears and diaphragms of dimensions of hundred microns or less have been fabricated successfully. Sensors have been manufactured that …

Study Of The Effects Of Sodium And Absorber Microstructure For The Development Of Cuin1-Xgaxse2-Ysy Thin Film Solar Cell Using An Alternative Selenium Precursor, Vinaykumar Hadagali

Electronic Theses and Dissertations

Thin film solar cells have the potential to be an important contributor to the world energy demand in the 21st century. CuInGaSe2 thin film solar cells have achieved the highest efficiency among all the thin film technologies. A steady progress has been made in the research and development of CuInSe2 based thin film solar cells. However, there are many issues that need to be addressed for the development of CuInSe2 based thin films solar cells. High price of PV modules has been a biggest factor impeding the growth of photovoltaic modules for terrestrial application. This thesis tries to address the …

A Direct Compensator Profile Optimization Approach For Intensity Modulated Radiation Treatment Planning, Kevin Erhart

Electronic Theses and Dissertations

Radiation therapy accounts for treatment of over one million cancer patients each year in the United States alone, and its use will continue to grow rapidly in the coming years. Recently, many important advancements have been developed that greatly improve the outcomes and effectiveness of this treatment technique, the most notable being Intensity Modulated Radiation Therapy (IMRT). IMRT is a sophisticated treatment technique where the radiation dose is conformed to the tumor volume, thereby sparing nearby healthy tissue from excessive radiation dose. While IMRT is a valuable tool in the planning of radiation treatments, it is not without its difficulties. …

Energy Conservation In The Trinidad Tourist Industry Training Program, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

This Final Report summarizes the work performed by the Florida Solar Energy Center/University of Central Florida on the contract entitled "Energy Conservation in the Trinidad Tourist Industry Training Program". This program was performed for the Ministry of Tourism, Trinidad and Tobago, WI. (MoTTT) for the period September 1 to November 1, 2008. The MoTTT established a program for the tourist industry to facilitate learning about energy conservation and renewable energy technologies appropriate for resort applications on the Island of Trinidad. The Florida Solar Energy Center provided assistance through consulting, in education about energy technologies. FSEC modified existing energy training courses …

Green And High Performance Factory Crafted Housing, Florida Solar Energy Center, Stephanie Thomas-Rees

FSEC Energy Research Center®

In the U.S., factory-built housing greater than 400 square feet is built either to the U.S. Department of Housing and Urban Development (HUD) code for mobile homes or site-built codes for modular housing. During the last few years, as the production of HUD code housing has dwindled, many leading edge factory builders have started building modular homes to compete with site-built housing and stay in business. As part of the Building America Industrialized Housing Partnership (BAIHP) we have assisted in the design and construction of several 'green' and high performance modular homes that Palm Harbor Homes, Florida Division (PHH) has …

Energy Impacts Of Various Residential Mechanical Ventilation Strategies, Florida Solar Energy Center, Robin Vieira

FSEC Energy Research Center®

The Building America program has been working with home builders for more than a decade using a variety of strategies for bringing fresh air into the homes. Many of these strategies utilize the central air handler fan from the HVAC system to ventilate when the system runs. Controllers can be purchased to force the air to enter for minimum periods of time or to shut off outside air dampers after some period of runtime. EnergyGauge USA, a detailed hourly residential simulation program, has been modified to simulate the various runtime strategies, as well as supply- or exhaust-only ventilation strategies and …

An Overview Of Building America Industrialized Housing Partnership (Baihp) Activities In Hot-Humid Climates, Florida Solar Energy Center, Subrato Chandra

FSEC Energy Research Center®

BAIHP (www.baihp.org ) conducts systems research and technical assistance activities for new housing. Hot-humid climate efforts described here include:

Systems research: NightCool – A hybrid cooling and dehumidification strategy employing radiative cooling and desiccant materials. Interior Duct Systems in Manufactured Houses – Tests are ongoing in an occupied prototype home in Alabama and the FSEC manufactured housing lab. Ventilation and Dehumidification – A new strategy has been developed to hook up a whole-house dehumidifier so that it only runs when the air conditioning compressor is off. Plug Load Reduction – Whole house feedback devices and security system based plug load …

Research Results From A Few Alternate Methods Of Interior Duct Systems In Factory Built Housing Located In The Hot Humid Climate, Florida Solar Energy Center, Neil Moyer

FSEC Energy Research Center®

The U.S. Department of Energy's (DOE) Building America Industrialized Housing Partnership (BAIHP) has collaborated with two of its industry partners to work on a portion of the project that relates to the construction and evaluation of prototype interior duct systems. In 2006, work began on a duct system design that would locate the entire length of duct work within the air and thermal barriers of the envelope. One of these designs incorporated a high-side supply register that connects to the conventional floor duct. The other design utilized a single soffit located within the conditioned space at the marriage line. The …

Assessment Of The Effectiveness And Energy Efficiency Of Humidity Control Approaches In Vacant Florida Homes, Florida Solar Energy Center, James Cummings

FSEC Energy Research Center®

In a hot and humid climate such as Florida, 'snowbirds' that leave their homes for extended summer periods need guidance on effective and energy efficient methods of humidity control. Experiments were performed in seven residences to evaluate various approaches to humidity control, including providing no mechanical system control. A humidity target was identified to maintain indoor relative humidity (RH) at 65% or lower most of the time. Providing no mechanical conditioning (letting the building 'float') yields relative humidity at 65% or below during hot and sunny weather in some homes, but not during cloudy weather. Setting the AC system thermostat …

Case Study Of An Innovative Hvac System With Integral Dehumidifier, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

In most applications, heating, ventilating, and air conditioning (HVAC) equipment is controlled to maintain an indoor dry-bulb set point temperature. Moisture removal by the HVAC system is considered to be an operational byproduct. During summer months, the operation of the HVAC system is usually sufficient to meet both the sensible and latent cooling loads. However, during other times of the year when sensible loads are reduced, the moisture load can be significantly higher than the available moisture removal capacity of the air conditioning system. This can lead to elevated indoor relative humidity levels and an uncomfortable indoor environment. In many …

Energy Performance Aspects Of A Florida Green Roof, Part 2, Florida Solar Energy Center, Jeffrey Sonne

FSEC Energy Research Center®

This monitored study is an evaluation of summer and winter energy performance aspects of a green roof on a 2-story central Florida university building addition that was completed in 2005. An earlier report on this study was published through the 2006 Symposium on Improving Building Systems in Hot and Humid Climates. This report reviews these earlier results and provides second-summer results which show significant performance improvements for the green roof compared with the first summer results.

Ac System Equipment Specification, Installation And Operational Options For Improved Indoor Humidity Control, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

High-efficiency home designs have significantly reduced sensible cooling loads, and some building codes and IAQ standards have begun requiring continuous outdoor ventilation air. These trends have led to an increased prevalence of high indoor humidity conditions (Rudd and Henderson 2007). This paper presents a summary of low-cost or no-cost equipment selection and operation options for conventional residential air-conditioning equipment than can result in lower indoor humidity levels. These options should be evaluated and employed to the extent possible prior to considering the added first cost and operating costs of separate dehumidification equipment.

Drilling, Alternative Fuels And Efficiency: Can The United States Wean Itself From Imported Oil?, Florida Solar Energy Center, Philip W. Fairey

FSEC Energy Research Center®

Perhaps the most daunting challenge the next generation of Americans will face is what President Bush called our "addiction to oil." The challenge is to find the means to provide for our transportation needs in the face of declining world oil production. Perhaps the central question is whether we will export the great wealth of America to foreign countries in payment for oil before we tackle the grand challenge of creating a new transportation future that does not rely completely on oil.

This article presents the historical facts relative to America's oil demand and domestic and world oil production resources. …

Overview And Summary Of Design Ideas From The High Performance Green Relocatable Classroom Charrette, Florida Solar Energy Center, Charles Withers, Jr.

FSEC Energy Research Center®

Past research has shown that energy use can be reduced by 81% in improved new portable classrooms in Florida. On June 2-3, 2008 a design charrette was held in Palm Beach Gardens with the goal of developing qualities that should be considered for a High-Performance Green Relocatable Classroom (HPGRC) standard for Florida or other regions in hot and humid climates. This charrette is just one of many steps that would be involved in development and acceptance of a HPGRC standard. It is hoped that the results of this can be shared with others and used to build on the development …

Furnace Blower Electricity: National And Regional Savings Potential, Florida Solar Energy Center, Victor Franco

FSEC Energy Research Center®

Currently, total electricity consumption of furnaces is unregulated, tested at laboratory conditions using the DOE test procedure, and is reported in the GAMA directory as varying from 76 kWh/year to 1,953 kWh/year. Furnace blowers account for about 80% of the total furnace electricity consumption and are primarily used to distribute warm air throughout the home during furnace operation as well as distribute cold air during air conditioning operation. Yet the furnace test procedure does not provide a means to calculate the electricity consumption during cooling operation or standby, which account for a large fraction of the total electricity consumption. Furthermore, …

Nightcool: A Nocturnal Radiation Cooling Concept, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

An experimental evaluation has been conducted on a night sky cooling system designed to substantially reduce space cooling needs in homes in North American climates. The system uses a sealed attic covered by a highly conductive metal roof (a roof integrated radiator) which is selectively linked by air flow to the main zone with the attic zone to provide cooling - largely during nighttime hours. Available house mass is used to store sensible cooling. Currently, the system's capability for solar dehumidification with minimal electricity input is demonstrated.

How Energy Efficient Are Modern Dishwashers?, Florida Solar Energy Center, David Hoak

FSEC Energy Research Center®

We present measurements of three recent vintage dishwashers of very different efficiencies showing that while they are substantially more efficient than older dishwashers, those tested will still use electric resistance elements for supplemental heat, even when supplied by solar water heating systems producing very hot water. We did find the DOE test results provide a reasonable guide to comparative performance, but suggest improvements that will make them more representative. We also identify a variety of influences on efficiency and performance to reduce dishwasher energy use.

Very Low Energy Homes In The United States: Perspectives On Performance From Measured Data, Florida Solar Energy Center, Danny Parker

FSEC Energy Research Center®

We present measured annual performance data from a dozen recent-vintage very low energy homes in North America. Many of the designs combine greater energy efficiency with solar electric photovoltaic power in an attempt to create Zero Energy Homes (ZEH). We also provide measured data from the first home constructed to the German Passivhaus standard in the United States. Several projects either exceeded or come very close to true net zero energy when evaluated over a year.

The data indicate that very low energy use buildings can very readily be achieved in North America. Annual energy use half that or less …

Ac System Equipment Specification, Installation And Operational Issues That Can Enhance Indoor Humidity Control, Florida Solar Energy Center, Don B. Shirey Iii

FSEC Energy Research Center®

This report presents summary of research on equipment selection and operation issues with conventional air conditioning equipment that can be employed prior to seeking the added first cost and operating cost of separate dehumidifiers.

Reducing Energy Use In Florida Buildings, Florida Solar Energy Center, Richard Raustad

FSEC Energy Research Center®

The 2007 Florida Building Code requires building designers and architects to achieve a minimum energy efficiency rating for buildings located throughout Florida. Although the Florida Building Code is strict in the minimum requirements for new construction, several aspects of building construction can be further improved through careful thought and design. This report outlines several energy saving features that can be used to ensure that new buildings meet a new target goal of 85% energy use compared to the current code requirements.

Solar 2007: Renewable Energy Disaster Relief Fund Gives A Helping Hand, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

In a disaster, support and utility services are damaged or destroyed leaving people without electricity, water, sanitation, and communication. Thousands of people from emergency management agencies and volunteer organizations are deployed to help after a disaster to provide life support and basic services. In this response effort, energy resources and services are lacking, making recovery efforts difficult in our high-tech world. In response to this problem, the National Energy Foundation and the Florida Solar Energy Center have formed the Renewable Energy Disaster Relief Fund (REDRF).

REDRF will collect donations from the general public, businesses, and various organizations through a variety …

Ahata Solar Energy Resort Training Program, Florida Solar Energy Center, William Young

FSEC Energy Research Center®

The Florida Solar Energy Center/University of Central Florida developed a Solar Energy Resort Training Program at the request of Aruba Bucuti Beach Resort Association, Aruba (AHATA) in the Caribbean Islands. The Aruba Resort Association has been interested in learning about and applying renewable energy technologies to their resorts to reduce energy consumption and cost. This report describes the activities and implementation of Florida Solar Energy Center's support to the Association to assist in the consulting, education and implementation of solar energy technologies into the resort industry in the country.