Thermodynamics Commons^™

Numerical Characterization Of The Flow Field And Heat Transfer Inside The Receiver Of A Parabolic Trough Solar Collector Carrying Supercritical Co2, Samad Gharehdaghimollahajloo

UNLV Theses, Dissertations, Professional Papers, and Capstones

The aim of this research is to provide a detailed numerical analysis of flow field and heat transfer inside the heat collecting element of a parabolic trough collector. The parabolic trough collector is used as the boiler in a direct Super Critical Carbon Dioxide (S-CO2) Brayton cycle.

A single collector is modeled and analyzed with different inlet conditions. The working fluid is supercritical since its pressure is increased to above critical pressure in the compressor while its temperature reaches 300 °C after passing through the recuperators and before entering the solar field. For the first time, this research considers both …

Thermodynamics Of Concentrated Solid Solution Alloys, Michael C. Gao, Chuan Zhang, Pan Gao, Fan Zhang, Lizhi Ouyang, Michael Widom, Jeffrey A. Hawk

Mathematical Sciences Faculty Research

This paper reviews the three main approaches for predicting the formation of concentrated solid solution alloys (CSSA) and for modeling their thermodynamic properties, in particular, utilizing the methodologies of empirical thermo-physical parameters, CALPHAD method, and first-principles calculations combined with hybrid Monte Carlo/Molecular Dynamics (MC/MD) simulations. In order to speed up CSSA development, a variety of empirical parameters based on Hume-Rothery rules have been developed. Herein, these parameters have been systematically and critically evaluated for their efficiency in predicting solid solution formation. The phase stability of representative CSSA systems is then illustrated from the perspectives of phase diagrams and nucleation driving …

Computational Modeling Of High-Entropy Alloys: Structures, Thermodynamics And Elasticity, Michael C. Gao, Pan Gao, Jeffrey A. Hawk, Lizhi Ouyang, David E. Alman, Mike Widom

Mathematical Sciences Faculty Research

This article provides a short review on computational modeling on the formation, thermodynamics, and elasticity of single-phase high-entropy alloys (HEAs). Hundreds of predicted single-phase HEAs were re-examined using various empirical thermo-physical parameters. Potential BCC HEAs (CrMoNbTaTiVW, CrMoNbReTaTiVW, and CrFeMoNbReRuTaVW) were suggested based on CALPHAD modeling. The calculated vibrational entropies of mixing are positive for FCC CoCrFeNi, negative for BCC MoNbTaW, and near-zero for HCP CoOsReRu. The total entropies of mixing were observed to trend in descending order: CoCrFeNi > CoOsReRu > MoNbTaW. Calculated lattice parameters agree extremely well with averaged values estimated from the rule of mixtures (ROM) if the same crystal …

Energy From Chemical Reactions: Understanding The Combustion Engine, Tammy Guthrie, Kathy Prophet, Greg Herzig, Cassie Kautzer

Middle School Lesson Plans

Automobiles produce a large amount of heat generated by the burning of gasoline. Burning gasoline is a chemical reaction that causes a phase change. This is called combustible energy. During combustion fuel combines with oxygen to release energy (such as heat, light, sound) along with another product that is often considered waste. Most of the energy produced is not used to power the automobile, but is released as heat. 19.3 pounds of the greenhouse gas, carbon dioxide, is produced from the combustion of 1 gallon of U.S. gasoline according to the U.S. Energy Information Administration.

Experimental Analysis Of R134a, R22, And R404 For An Edibon Taab: Air Conditioning Lab Unit, Kyle T. Heesen

Senior Honors Projects, 2010-2019

This paper presents an experimental analysis of an Ebidon® TAABTM: Air Conditioning Lab unit running on R-134a being compared with R22 and R404 refrigerants, a $24,449 piece of equipment purchased by the JMU ISAT Department. In this paper we will compare the performance of the R-134a refrigerant under a range of working conditions and compare them to how the system would run on R22 or R404. The experimental tests use varying fan speeds and the R-134a data collected is compared to simulated data collected for R22 and R404. Analysis of the collected data and simulated data will be compared on …

Passive Solar Distillation Of Acid Rock Drainage, Stephanie Shreve, Luke Galuska, Anna Stoller, Alex Raney, Agustin Caceres, Caitlyn Chambers, Chris Graham, Devin Hazlett

Chemical Engineering Undergraduate Honors Theses

Arkansas Razorback Distillers (A.R.D.) has developed a passive solar distillation system for treating acid rock drainage (ARD) from legacy (i.e., abandoned) mines. The solar still addresses the need to reduce both the metal sulfate contaminants as well as the acidity of acid rock drainage. During the design phase, A.R.D. addressed the need for the system to be low cost, simple, and effective for general use as well as a specified location. To demonstrate the applicability of the solar still, A.R.D. used the Freeport McMoRan Inc. Copper Queen legacy mine in Bisbee, Arizona, as a base case scenario. The mine was …

Molecular Modeling Of Antibody-Antigen Binding Near Solid Surfaces, Derek Bush, Thomas Knotts

Biomedical Engineering Western Regional Conference

Antibody microarrays are biosensors that have the potential to revolutionize molecular detection in medicine, scientific research, and national defense. However, current microarrays are not widely used due to problems including poor reproducibility and signal quality, unbalanced antibody performance, and cross-reactivity. Prior work in the area focused mainly on the stability of the antibody alone and not its affinity for its antigen. This presentation shows results of using molecular simulation to determine how different types of surfaces affect antigen binding to surface-tethered antibodies. The results offer an unprecedented, molecular-level view into these protein-protein-surface interactions and how to drive binding to occur.

Surface Chemisty Study Of Monazite Flotation In Coal Refuse Systems, Wencai Zhang

Theses and Dissertations--Mining Engineering

Rare earth mineral recovery from alternative resources such as coal and coal byproducts is increasingly important to provide an opportunity for economic recovery from U.S. sources. Currently, China produces the majority of the 149,000 tons of rare earth elements used annually worldwide of which the U.S. imports 11% or around 16,000 tons. There are no significant mining operations producing rare earth elements in the U.S. However, there are many U.S. sources containing rare earth minerals such as monazite including heavy mineral sand and phosphate operations. Monazite mineral particles of a few microns have also been detected in Fire Clay seam …

Method For Carbon Dioxide Splitting, James E. Miller, Richard B. Diver, Nathan P. Siegel

Other Faculty Research and Publications

A method for splitting carbon dioxide via a two-step metal oxide thermochemical cycle by heating a metal oxide compound selected from an iron oxide material of the general formula A_xFe_3-xO₄, where 0≦x≦1 and A is a metal selected from Mg, Cu, Zn, Ni, Co, and Mn, or a ceria oxide compound of the general formula M_aCe_bO_c, where 0

Heat Transfer Analysis In A Paddle Reactor For Biomass Fast Pyrolyis, Ankith Ullal

Dissertations, Master's Theses and Master's Reports

Heat transfer analysis was performed on a novel auger reactor for biomass fast pyrolysis. As part of this analysis, correlations for specific heat capacity and heat transfer coefficients for biomass (sawdust) and sand (used as heat transfer medium) were developed. For sand, the heat transfer coefficient followed a power law distribution with reactor fill level and temperature. For raw biomass, the heat transfer coefficient also showed similar dependence on fill level, but was independent of temperature up to 300°C. These correlations were used in a one dimensional heat transfer model developed to calculate the heating time and heating rate of …

Hybrid Metal Oxide Cycle Water Splitting, Richard B. Diver Jr., Robert D. Palumbo, Nathan P. Siegel, James E. Miller

Other Faculty Research and Publications

Hybrid thermochemical water splitting systems are disclosed that thermally reduces metal oxides particles to displace some but not all of the electrical requirements in a water splitting electrolytic cell. In these hybrid systems, the thermal reduction temperature is significantly reduced compared to two-step metal-oxide thermochemical cycles in which only thermal energy is required to produce hydrogen from water. Also, unlike conventional higher temperature systems where the reduction step must be carried out under reduced oxygen pressure, the reduction step in the proposed hybrid systems can be carried out in air, allowing for thermal input by a solar power tower with …

Understanding Glycoside Hydrolase Processivity For Improved Biomass Conversion, Suvamay Jana

Theses and Dissertations--Chemical and Materials Engineering

In nature, organisms secrete synergistic enzyme cocktails to deconstruct crystalline polysaccharides, such as cellulose and chitin, to soluble sugars. The cocktails consist of multiple classes of processive and non-processive glycoside hydrolases (GH) that aid in substrate accessibility and reduce product inhibition. Processive GHs attach to chain ends and hydrolyze many glycosidic linkages in sequence to produce disaccharide units before dissociation, and as such, are responsible for the majority of hydrolytic bond cleavages. Accordingly, processive GHs are targets for activity improvements towards efficient and economical biomass conversion. However, the mechanism and factors responsible for processivity are still not understood completely at …