Chemical Engineering 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 …

A Comparison Of Mean Age Theory And Residence Time Distributions In Mixed Systems., Nolan Theaker

Electronic Theses and Dissertations

A comparison between mean age theory and conventional residence time distributions over a range of quantified mixing levels was conducted using computational fluid dynamics (CFD). The system was a stirred tubular reactor. The model was validated by comparing computationally derived RTD curves with experimentally obtained RTD curves, with quantified differences less than 3%. Mixing was quantified using the Tanks-in-Series model. Mixing levels were set by varying flow rate and impeller rpm. Mean age distributions at the outlet, where experimental RTD’s were measured, were very narrow for all levels of mixing studied. RTD’s showed expected characteristics; a wider distribution and long …

Anodic Catalysts For Anion Exchange Membrane Fuel Cells, Aaron Joseph Roy

Chemical and Biological Engineering ETDs

With a limited availability of energy resources from petroleum and other fossil fuels, as well as growing concerns relating to the environmental implications of fossil fuel emissions, non-carbon fuels which can be utilized in proton and anion exchange membrane fuel cells (PEMFC’s/AEMFC’s), such as hydrogen and hydrazine hydrate (HH), are becoming more attractive as alternative fuels. Historically, platinum and platinum group metal catalysts (PGM) have been used as cathode and anode catalyst materials for both PEMFC’s and AEMFC’s. Although these catalysts are the highest performing catalysts available for the conversion of hydrogen energy in fuel cells, the limited availability and …

Comparison Study Between Post-Fermentation Stillage And Pre-Fermentation Mash Utilizing Acidification And Steam Explosion Techniques For Cellulose Saccharification, Daniel Mckee

Master's Theses

Pre-fermentation mash fiber and post-distillation stillage fiber were examined and compared using a variety of preparatory techniques to determine the better source for cellulose fiber saccharification. Once screened, dried, and diluted to a 10% solution, mash fiber and stillage fiber were exposed to increasing temperatures for steam explosion techniques as well as increasing acidification techniques. Both underwent enzymatic saccharification to convert the exposed cellulose to glucose and other sugars. Once the optimum steam explosion technique parameters and acidification parameters were determined to be 2.5% sulfuric acid at 127.8°C for 1 hour, a comparison of the saccharification of pre-fermentation mash fiber …

Ptfe-Based Microreactor System For The Continuous Synthesis Of Full-Visible-Spectrum Emitting Cesium Lead Halide Perovskite Nanocrystals, Chengxi Zhang, Weiling Luan, Yuhang Yin, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Colloidal perovskite nanocrystals comprised of all inorganic cesium lead halide (CsPbX₃, X = Cl, Br, I or a mixture thereof) have potential as optical gain materials due to their high luminescence efficiency. In this work, cesium lead halide nanocrystals are continuously synthesized via a microreactor system consisting of poly(tetrafluoroethylene) (PTFE) capillaries. The synthesized nanocrystals possess excellent optical properties, including a full width at half maximum of 19–35 nm, high fluorescence quantum yield of 47.8–90.55%, and photoluminescence emission in the range of 450–700 nm. For the same precursor concentrations, the photoluminescence emission peak generally increases with increasing reaction temperature, …

Non-Additive Impacts Of Covalent Cross-Linking On The Viscoelastic Nanomechanics Of Ionic Polyelectrolyte Complexes, B. Han, T. Ma, J. H. Vergara, Giuseppe R. Palmese, J. Yin, D. Le

Henry M. Rowan College of Engineering Departmental Research

This study elucidates the influences of adding covalent cross-linking on the nanomechanical viscoelasticity of ionically cross-linked polyelectrolyte networks. Using layer-by-layer (LbL) assembled PAH/PAA networks, we report how adding covalent amide cross-links changes the degree of swelling, indentation modulus, and force relaxation behaviors with varying solution conditions such as pH and ionic strength, which modulate the ionic cross-link density and fixed charge density. The addition of covalent cross-linking increases both the modulus and degree of elasticity through providing permanent anchorage to the ionically linked networks. Such addition also strongly increases the relaxation times at net neutral, less swollen states. These results …

Effect Of Oxide On Surface Tension Of Molten Metal, Chunkai Li, Yu Shi, Yufen Gu, Fuqian Yang

Chemical and Materials Engineering Faculty Publications

Oxides as one of the commonly activating fluxes used in active tungsten inert gas welding (A-TIG welding) can dramatically increase the penetration depth to 2–4 times that of conventional welding. Using the oscillation principle of inviscid fluid, a robust method is developed to measure the average surface tension of molten metal during A-TIG welding for four different oxide activating fluxes of B₂O₃, TiO₂, SiO₂, and MgO. The experimental results suggest that the oxygen released from the decomposition of oxides is the dominant factor contributing to the change of the surface tension, which …

High-Throughput Droplet Barcoding And Automated Image Analysis In Microfluidic Droplet Trapping Array, Manibarathi Vaithiyanathan

LSU Master's Theses

Molecularly-targeted therapeutics and personalized medicine have dramatically increased the median survival rate of patients suffering from cancer. However, cellular heterogeneity and the personalized nature of cancer have resulted in the limited success of single drug treatments which has led to the use of multiple therapeutic combinations. This has required the development of new analytical methods capable of multiplexed high-throughput screening (HTS) technologies necessary to identify is single or multi-agent therapies are effective in ex vivo samples like liquid biopsies. Droplet microfluidic devices have garnered significant interest to facilitate high-throughput, single cell analysis of heterogeneous populations. However, these devices are still …

Mechanistic Modeling Of Nanoparticle-Stabilized Supercritical Co2 Foams And Its Implication In Field-Scale Eor Applications, Doris Patricia Ortiz Maestre

LSU Master's Theses

Previous experimental studies show that nanoparticle-stabilized supercritical CO₂ foams (or, NP CO₂ foams) can be applied as an alternative to surfactant foams, in order to reduce CO₂ mobility in gas injection enhanced oil recovery (EOR). These nanoparticles, if chosen correctly, can be an effective foam stabilizer attached at the fluid interface in a wide range of physicochemical conditions.

By using NP CO₂ foam experiments available in the literature, this study performs two tasks: (i) presenting how a mechanistic foam model can be used to fit experimental data and determine required model parameters, and (ii) investigating the …

Pollution Prevention In The Great Lakes Basin: Working With Pulp & Paper Manufacturers, Eugene Park

Journal of Environmental Sustainability

In response to growing concerns over persistent toxic substances in the Great Lakes, new initiatives are in place to address and mitigate pollutant loadings to these large natural waterbodies. With support from the U.S. Environmental Protection Agency and New York Department of Environmental Conservation, the New York State Pollution Prevention Institute (NYSP2I) worked with pulp & paper companies in the Great Lakes Basin in an effort to find solutions to reduce environmental impacts from this industry sector. Based on currently available EPA toolkits, NYSP2I developed and utilized an assessment tool called Lean, Energy, and Environment (LE2). Five different paper manufacturers …

Microbial Desalination Cells With Efficient Platinum Group Metal-Free Cathode Catalysts, Morteza Rezaei Talarposhti

Chemical and Biological Engineering ETDs

Iron-nitrogen-carbon based catalyst was used at the cathode of a microbial desalination cell (MDC) and compared with platinum (Pt) and activated carbon (AC) cathode. Fe-N-C catalyst was prepared using nicarbazin (NCB) as organic precursor by sacrificial support method (SSM). Rotating ring disk electrode (RRDE) experiments shows that Fe-NCB had higher electrocatalytic activity compared to AC and Pt. The utilization of Fe-NCB into the cathode improved substantially the performance output with initial maximum power density of 49±2 μWcm^-2 in contrast to Pt and AC catalysts which have shown lower values of 34±1 μWcm^-2 and 23.5±1.5 μWcm^-2, respectively. …

The Control Of Water Contaminants Assisted By Natural Materials, Wen Zhao

USF Tampa Graduate Theses and Dissertations

Natural materials can be used to remove water contaminants by applying proper physical, chemical, and biological water treatment processes. This study involves using natural materials, as they are considered to be more environmentally benign and cost-effective than synthetic materials. This dissertation concentrates on monitoring five major water quality parameters—ammonia, fluoride, turbidity, pH, and fecal indicator bacteria (FIB) —in two major applications where clean water is needed. The focus is on meeting the water quality requirements for each contaminant. The overall objective of this study is to control the levels of ammonia in aquaculture wastewater, and adjust fluoride, turbidity, pH, and …

Green Synthesis Of Copper Oxide Nanoparticles In Aqueous Medium As A Potential Efficient Catalyst For Catalysis Applications, Hany A. Elazab Dr

Chemical Engineering

In this research, we have developed a reliable green method for the synthesis of copper oxide nanoparticles as a potential efficient catalyst for several catalysis applications. In our experimental approach, microwave-assisted synthesis technique was used in order to perform chemical reduction of copper salt using hydrazine hydrate as a strong reducing agent. The prepared catalyst was characterized using various techniques showing the formation of well dispersed copper oxide nanoparticles. The synthesized Copper oxide catalyst shows many advantages including the use of environmentally benign solvent systems,

What Happens To Nox Emissions Of Vw Diesel Cars When Water/Methanol Injection Is Used?, Andrew Croxell

ASA Multidisciplinary Research Symposium

Volkswagen has come under fire for their "Clean Diesel" automobiles that were found to emit too much NOx (Oxides of Nitrogen) when driven on the street. Since NOx is created by high temperature combustion events, the addition of a water/methanol injection system was tested on a VW diesel vehicle to identify if it could cool combustion temperatures and thus reduce NOx to an acceptable specification.

Gender And Participation In An Engineering Problem-Based Learning Environment, Laura Hirshfield, Milo D. Koretsky

Interdisciplinary Journal of Problem-Based Learning

The use of problem-based learning (PBL) is gaining attention in the engineering classroom as a way to help students synthesize foundational knowledge and to better prepare students for practice. In this work, we study the discourse interactions between 27 student teams and two instructors in an engineering PBL environment to analyze how participation is distributed among team members, paying particular attention to the differences between male and female students. There were no statistically significant differences between the amount that male and female students spoke; however, stereotypical gender roles and traditional gendered behavior did manifest in the discussion. Also, regardless of …

Life Cycle Analysis For Algae Biofuels-Using Local Situations To Factor In The Cost/Benefit Of High-End Products Along With Nutrient Remediation And Co2 Sequestration, John Korstad, Joe T. Moore

College of Science and Engineering Faculty Research and Scholarship

Algae as a feedstock for commercial biofuels is best suited for sunny and warm areas with abundant fresh, salt, or brackish water. Optimum areas worldwide are in the tropics. Logical areas in North America include the Southeast Gulf coast and perhaps New Mexico. Additional practical areas on smaller scale probably lie in metropolitan locations, especially near international airports. The cost-benefit of these endeavors can be enhanced when factors such as high-end products alongside collaboration with sewage treatment or other waste water remediation, industrial carbon dioxide sequestration, reduced transport distance of fuels, and other aspects of the local economy are taken …

Modelling And Simulation Of Hydrogen Production Via Membrane Reactor, Aya Abdel-Hamid Smail Mourad

Chemical and Petroleum Engineering Theses

A membrane reactor is a promising device to produce pure hydrogen and enrich CO₂ from syngas. A simulation study of a double tubular catalytic membrane reactor for the water-gas shift reaction (WGS) under steady-state operation is presented in this work. The membrane consists of a dense Pd layer (selective to H₂) deposited on a porous glass cylinder support. The reaction side was filled with a commercial iron-chromium oxide catalyst, designed as Girdler G-3. The mass of the catalyst was 12.1 g and the height of the catalyst bed was 8 cm. The WGS model was carried out …

Investigation Of The Effect Of Supercritical Carbon Dioxide Extraction On The Adsorption Capacity Of Date Pits, Haliemeh Imad Sweidan

Chemical and Petroleum Engineering Theses

This thesis aims to develop and investigate an innovative use of date pits, a common and abundant agricultural waste in the UAE. It is suggested that date pits may be used to produce date pit oil, and the powder residue from this extraction process may be used as a low cost adsorbent for removal of lead from water. This thesis aims to investigate the effects of the parameters pressure, temperature, and particle size on the extraction yield when using supercritical carbon dioxide (SC-CO₂) to extract oil from date pit powder. This oil is a valuable component which has many applications …

A Multiscale Modeling Study Of Particle Size Effects On The Tissue Penetration Efficacy Of Drug-Delivery Nanoparticles, Mohammad Aminul Islam, Sutapa Barua, Dipak Barua

Chemical and Biochemical Engineering Faculty Research & Creative Works

Background: Particle size is a key parameter for drug-delivery nanoparticle design. It is believed that the size of a nanoparticle may have important effects on its ability to overcome the transport barriers in biological tissues. Nonetheless, such effects remain poorly understood. Using a multiscale model, this work investigates particle size effects on the tissue distribution and penetration efficacy of drug-delivery nanoparticles.

Results: We have developed a multiscale spatiotemporal model of nanoparticle transport in biological tissues. The model implements a time-adaptive Brownian Dynamics algorithm that links microscale particle-cell interactions and adhesion dynamics to tissue-scale particle dispersion and penetration. The model accounts …

Metabolomic Effects Of Ceo₂, Sio₂ And Cuo Metal Oxide Nanomaterials On Hepg2 Cells, Kirk T. Kitchin, Steve Stirdivant, Brian L. Robinette, Benjamin T. Castellon, Xinhua Liang

Chemical and Biochemical Engineering Faculty Research & Creative Works

Background: To better assess potential hepatotoxicity of nanomaterials, human liver HepG2 cells were exposed for 3 days to five different CeO₂ (either 30 or 100 μg/ml), 3 SiO₂ based (30 μg/ml) or 1 CuO (3 μg/ml) nanomaterials with dry primary particle sizes ranging from 15 to 213 nm. Metabolomic assessment of exposed cells was then performed using four mass spectroscopy dependent platforms (LC and GC), finding 344 biochemicals.

Results: Four CeO₂, 1 SiO₂ and 1 CuO nanomaterials increased hepatocyte concentrations of many lipids, particularly free fatty acids and monoacylglycerols but only CuO elevated lysolipids and …