Engineering Commons^™

Mixed Convection In Horizontal Channels Heated Below With External Heat Losses On Upper Plate And Partially Filled With Aluminum Foam, Bernardo Buonomo, Oronzio Manca, Lorenzo Marinelli, Sergio Nardini

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

In this paper an experimental investigation on mixed convection in air in a heated channel partially filled with an aluminum foam is carried out. The aluminum foam layer is sets on the lower heated wall of the channel. The channel upper plate has a heat transfer toward the external ambient. The investigation allows to evaluate the effect of the aluminum foam on the mixed convection in the heated channel by wall temperature measurements and flow visualization. Results are given for heated channel without and with foam in terms of wall temperature profiles for different Reynolds number value, form 10 to …

Comparative Analysis Of Geometric Models For Predicting The Dynamic Specific Surface Of Foamlike Media, Sonia Woudberg, Francois Smit

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

An adaptable geometric pore-scale model is proposed for predicting the specific surface area of actual foams. The proposed model, based on rectangular geometry, is compared to a cubic unit cell model from the literature based on cylindrical struts, a tetrakaidecahedron model as well as a dodecahedron model (both based on either cylindrical of triangular struts). The predicted specific surface areas of the proposed model are of the same order of magnitude as the other model predictions from the literature. The relative percentage errors in the predicted values are at most equal to the relative percentage errors associated with the measured …

Columnar Structured Thermal Barrier Coatings By Thermal Spray Methods, Robert Vassen, Nadine Schlegel, Stefan Rezanka, Georg Mauer, Emine Bakan, Daniel Mack

Thermal Barrier Coatings IV

No abstract provided.

Process Control & Automation Of A Batch Reactor, James Kelly

Dissertations

The development of a split range PID controller with SCADA screens to facilitate manual and automatic control of a pilot plant scale batch reactor is presented in this thesis. Since the characteristics of the system were unknown a step response was obtained from the system and from the experimental results a model of the system was developed and analysed. The PID controller for the system was implemented via an Allen Bradley MicroLogix 1100 Programmable Logic Controller with the human interface for the controller being a SCADA system that was developed using the software package LabVIEW a visual programming language. From …

Multilayered Thermal Barrier Coatings, Xueqiang Cao

Thermal Barrier Coatings IV

A novel non-destructive inspection technique was developed to measure the residual stresses in TBCs by using Eu3+ photoluminescence piezo-spectroscopy. The relationship between the strongest peak of 5D0→7F2 and stress was determined by the high-pressure experiments and used to evaluate the residual stresses. When the top ceramic coat LZ7C3 in the double-layered coating LZ7C3/YSZ:Eu spalled, the inner YSZ:Eu could produce visible luminescence under UV illumination, providing an indication of the spallation location. The LZ7C3/YSZ:Eu coating spalled bit by bit from LZ7C3 to YSZ:Eu during thermal cycling. The similar thermal expansions of LZ7C3 and YSZ:Eu prolonged the thermal cycling life of the …

Integrated Electrostatically- And Piezoelectrically-Transduced Contour-Mode Mems Resonator On Silicon-On-Insulator (Soi) Wafer, I-Tsang Wu

USF Tampa Graduate Theses and Dissertations

Due to the recent rapid growth in personal mobile communication devices (smartphones, PDA's, tablets, etc.), the wireless market is always looking for new ways to further miniaturize the RF front-ends while reducing the cost and power consumption. For many years, wireless transceivers and subsystems have been relying on high quality factor (Q) passives (e.g., quartz crystal, ceramics) to implement oscillators, filters, and other key RF front-end circuitry elements. However, these off-chip discrete components occupy large chip area and require power-demanding interfacing circuits. As a result, a great deal of research effort has been devoted to the development of …

Applying Modeled Hemi-Ellipsoids To The Study Of Pressure Distribution In Normal And Paraplegic Seated Subjects, Alicia Billington

USF Tampa Graduate Theses and Dissertations

The three goals of this research were to investigate how normal subjects move while seated, how paraplegic patients move while seated, and whether seated movements can be modeled using a hemi-ellipsoid shape. Pressure readings were recorded at 11 Hz using a 36 by 36 sensor pressure map by XSENSOR. Subjects were instructed to move or perform pressure relief as they normally would while seated. Analysis was performed using Microsoft Excel with Solver and Matrix.xla add-ins and automated with VBA code. Major movements and time intervals between movements were calculated by locating the area of maximum pressure on each hemi-buttock for …

College Of Engineering News, Georgia Southern University

College of Engineering & Computing: News & Publications (2010-2023)

• EE Dept. Wins Grant for Solar Powered Service Golf Carts

Effect Of Composting On The Fate Of Steroids In Beef Cattle Manure, Shannon L. Bartelt-Hunt, Shannon Devivo, Leslie J. Johnson, Daniel D. Snow, William Kranz, Terry L. Mader, Charles Shapiro, Simon Van Donk, David P. Shelton, David Tarkalson, Tian C. Zhang

Department of Civil and Environmental Engineering: Faculty Publications

In this study, the fate of steroid hormones in beef cattle manure composting is evaluated. The fate of 16 steroids and metabolites was evaluated in composted manure from beef cattle administered growth promotants and from beef cattle with no steroid hormone implants. The fate of estrogens (primary detected as estrone), androgens, progesterone, and the fusarium metabolite and implant a-zearalanol was monitored in manure compost piles. First-order decay rates were calculated for steroid half-lives in compost and ranged from 8 d for androsterone to 69 d for 4-androstenedione. Other steroid concentration data could not be fit to first-order decay models, which …

Characterizing The Pore Structure Of Carbonated Natural Wollastonite, Chiara Villani, Robert Spragg, Raikhan Tokpatayeva, Jan Olek, W. Jason Weiss

International Conference on Durability of Concrete Structures

This paper focuses on examining the pore structure of a cementitious paste made with a calcium silicate (wollastonite) that reacts with carbon dioxide and water to form a hardened solid. The pore structure of the hardened solid has been characterized using vapor sorption and desorption, low-temperature differential scanning calorimetry (LT-DSC), and scanning electron microscopy (SEM). The total porosity was also measured using mass measurement in oven-dry and vacuum-saturated conditions. Evidence exists that support the hypothesis that the solid has two main pore sizes: large macropores (>10 nm) appear to form between the initial calcium silicate particles and small micropores …

Synthesis, Characterization And Mechanistic Studies Of Biomolecules@Mesomofs, Yao Chen

USF Tampa Graduate Theses and Dissertations

Encapsulation of biomolecules is of great interest to research advances related to biology, physiology, immunology, and biochemistry, as well as industrial and biomedical applications such as drug delivery, biocatalysis, biofuel, food and cosmetics. Encapsulation provides functional characteristics that are not fulfilled by free biomolecules and stabilizes the fragile biomolecules. In terms of biocatalysis, solid support can often enhance the stability of enzymes, as well as facilitate separation and recovery for reuse while maintaining activity and selectivity. Various kinds of materials have been used for encapsulation of biomolecules, among which, porous materials are an important group. Metal-organic frameworks (MOFs) have attracted …

Low-Cost Household Groundwater Supply Systems For Developing Communities, Michael Maccarthy

USF Tampa Graduate Theses and Dissertations

ABSTRACT

Self-supply is widely reported across various contexts, filling gaps left by other forms of water supply provision. This research assesses low-cost household groundwater supply technologies in markets in developing country contexts of sub-Saharan Africa and Latin America, with a focus on the potential for improving Self-supply technology implementation and markets in sub-Saharan Africa. Specifically, a mature and unsubsidized Self-supply market for Pitcher Pump systems (suction pumps fitted onto hand-driven boreholes) is studied in an urban context in Madagascar, EMAS low-cost water supply technologies are assessed in Bolivia, and a technical comparison is completed with manual EMAS Pumps and family …

Thermal Properties Of Highly Porous Fibrous Ceramics, Jingjing Sun, Zijun Hu, Jiejie Zhuo, Xiaoyan Wang, Chencheng Sun

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Highly porous fibrous ceramics were fabricated by vacuum-molding the fiber slurry and sintering the dried felt. The materials comprised of a random network of ceramic fibers and air, with the pore sizes on micron scale. The effects of binder content and porosity on the microstructure and room-temperature thermal conductivity of fibrous ceramics were investigated. It was found that the room-temperature thermal conductivity increased with increasing binder content. In addition, the thermal conductivity decreased from 0.18 to 0.06 W/(m·K) when porosity increased from 73% to 90%, showing nearly a linear relationship. The high-temperature thermal conductivity in the range of 200-1200℃ for …

Fabrication And Microstructural Characterization Of Silica Aerogel By Aging Additional Pressurization, Xiaoyan Wang, Zijun Hu, Chencheg Sun, Jiejie Zhou, Zhao Song

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

SiO2 aerogel with Light-weight and low thermal conductivity is a promising candidate for thermal insulator used for aerospace vehicles. In this paper, we report the preparation and microstructural characterization of SiO2 aerogel by aging pressurization using supercritical drying method. The results showed that the aging pressurization can rapid increase the bulk density from 0.1g/cm3 to 0.45g/cm3 with the pressure changing from 200Pa to 600Pa. When the pressure increases to 800Pa, the density was increased to 0.46g/cm3 slowly. Further polycondensation is driven by the increasing of contact area between skeleton particles when the aging pressure increased. The grid structure became densification …

Sensitivity Analysis Of Effective Thermal Conductivity Of Open-Cell Ceramic Foams Using A Simplified Model Based On Detailed Structure, Miguel Mendes, Amjad Asad, Pitt Gotze, Eric Werzner, Rhena Wulf, Dimosthenis Trimis, Ulrich Grob, Subhasis Ray

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The Effective Thermal Conductivity (ETC) of open-cell porous foams can be predicted from the detailed numerical simulation, considering the complex foam structure obtained from three-dimensional (3D) Computed Tomography (CT)-scan images. An alternative approach could be to consider simplified models for a quick and accurate estimation of the ETC. A model for ETC of open-cell porous foams, using such a simplified approach, has been proposed recently which relies upon a single numerical prediction of the dimensionless ETC under vacuum condition, evaluated using the detailed foam structure obtained from 3D CT-scan information. This model is applied in the present study in order …

Droplet Impact And Penetration On Series Of Parallel Tubes, S. Hosseini, A. Dalili, Nasser Ashgriz, S. Chandra

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Impact and penetration of a liquid droplet on a substrate having a line of parallel capillary openings drilled along its thickness is experimentally studies. Different regimes of droplet penetration are identified. At low impact velocities, the droplet impacts on the substrate, spreads, and penetrates into the substrate mainly due to the capillary action in each tubular hole. At higher impact velocities, the droplet impacts on the substrate, spreads and penetrates due to the droplet inertia, and then penetrates further due to the capillary action. Threshold velocities for liquid penetration into capillary tubes are identified. Two penetration regimes, capillary and inertia …

The Preparation And Properties Of Novel Structural Carbon Foams Derived From Different Mesophase Pitches, Liqiong Yu, Zhihai Feng, Zhen Fan, Qing Kong, Lin Xu

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

As a novel porous multi-functional carbon material, carbon foams have high bulk thermal conductivity and low density, making them as excellent materials for thermal management systems applications, such as heat exchangers, space radiators, and thermal protection systems. In this paper, the carbon foams with high thermal conductivity, derived from three kinds of mesophase pitches, were fabricated by the process of foaming, carbonization and graphitization. The microstructures of the foams were examined by scanning electron microscopy. It was found that the pores were uniformly distributed, and the pore wall thickened with increasing foams’ density. The properties of the foams were studied, …

Effective Solid-To-Fluid Heat Transfer Coefficient In Egs Reservoirs, Xiao-Long Ouyang, Rui-Na Xu, Pei-Xue Jiang

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

The present work developed a three-equation local thermal non-equilibrium model to predict the effective solid-to-fluid heat transfer coefficient in the enhanced geothermal system reservoirs based on the volume averaging method. Due to the high rock-to-fracture size ratio, the solid thermal resistance effect in the internal rocks cannot be neglected in the effective solid-to-fluid heat transfer coefficient. The present three-equation local thermal non-equilibrium model can consider the dynamic variation of the solid thermal resistance in transient heat transfer by introducing the penetration temperature difference. The model was validated by comparison with pore-scale numerical simulations and macro-scale LTNE model numerical simulations. The …

Improved Permeability Prediction For Heterogeneous Porous Media By Bundle-Of-Leaky-Tubes With Cross-Flow Model, Faruk Civan

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

An inherently limiting assumption of the Kozeny-Carman equation of permeability is not allowing interaction across the parallel flow through a bundle of tubes model. While this condition can be observed for flow through sufficiently high porosity homogeneous porous media, the Kozeny-Carman equation cannot represent the permeability of low porosity heterogeneous porous media. This paper presents a modeling of flow through a leaky-flow tube allowing interactions with flow occurring in other flow tubes in a bundle of tubes model of porous media. Then, the effect of such interactions is taken into account by incorporating the pore connectivity by means of the …

Porous Structures Used As Flameproof Pressure Relief Elements A Novel Approach Of Flameless Venting, Julia Hornig, Detlev Markus, Martin Thedens

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Here, a novel approach to flameless venting is presented, which offers the possibility of improving the design of flameproof enclosures without reducing any safety aspects. This approach is based on the integration of porous structures – such as traditional sintered metals or sintered metal fibers – into the enclosure walls acting as venting and flame-quenching elements. It is shown that proper use of these structures can enormously decrease the maximum explosion pressure while safely avoiding flame transmissions, even for a large number of consecutive internal explosions. However, the transmission of a gas explosion through porous structures is a transient and …

Keynote – Nonlinear Natural Convection In Porous Media And The Collapse Of The Wave Function, Peter Vadasz

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

A short review of the problem of nonlinear natural convection in a fluid saturated porous layer heated from below is presented. When the conditions for the onset of convection are met a wave function is obtained as the solution of the linearized equations expressed in terms of a Fourier expansion. Only one mode of this expansion survives at the onset of convection, a result that can be seen as the "Collapse of the Wave function" in a very similar fashion as in quantum mechanics, although the explanations of the latter are very distinct from the ones in quantum mechanics. The …

Effect Of Bondcoat Roughness On Lifetime Of Aps-Tbc Systems In Dry And Wet Gases, W.J. Quadakkers, D. Naumeko, P. Mor, W. Nowak, L. Singheiser

Thermal Barrier Coatings IV

Low pressure plasma spraying (LPPS) is a process commonly used for deposition of MCrAlY (M=Ni,Co) bondcoats for air plasma spray thermal barrier coatings (APS-TBCs). LPPS produces bondcoats with a high roughness and good oxidation resistance, which are known to play a key role for long lifetimes of APS-TBC’s. An alternative process for the bondcoat deposition is high velocity oxy-fuel (HVOF), which is substantially cheaper than LPPS but even with well optimized spraying parameters generates intrinsically lower bondcoat roughness. In the present work it is shown that a bi-layer MCrAlY-bondcoat consisting of an HVOF-base layer and an upper, thin APS-flashcoat of …

Application Of Eq Bond Coat To Eb-Pvd Tbc Systems, Kazuhide Matsumoto, Kyoko Kawagishi, Yutaka Koizumi, Hiroshi Harada

Thermal Barrier Coatings IV

To prevent the formation of SRZ in the log-time high-temperature exposure of the turbine blades, thermodynamically equilibrium phase such as gamma-prime phase of the substrate is use as an oxidation-resistant bond coat. The previous study clarified that this EQ coating shows excellent interface stability and it does not degrade mechanical strength due to the SRZ formation. In this study, TBC life test of EB-PVD ceramics coated EQ coating is investigated with other conventional MCrAlY coatings. The 4th and 5th generation superalloys are used for substrates. About 150 μm thick of EQ coating, conventional NiCoCrAlY and CoNiCrAlY coating are deposited by …

The Role Of Reactive Elements In Improving The Cyclic Oxidation Performance Of Β- Nial Coatings, Hongbo Guo, Hui Peng, Dongqing Li, Tian Zhang, Shengkai Gong

Thermal Barrier Coatings IV

the bond coat in thermal barrier coating (TBC) system. However, the oxide scale grown on NiAl spalls readily during high-temperature cyclic oxidation. Reactive elements (REs) as well as their oxides dispersions were investigated to improve the cyclic oxidation performance. In this work, the effects of several REs on the adherence of Al2O3/NiAl interface were investigated by first principles theory calculations and experiments. We find that the solubility of the REs in NiAl alloy arrive at an order of Hf >Zr>Dy>Y>La, all the REs exhibit an affinity for sulfur, with an order of La>Dy>Y>Zr>Hf, …

A Recent History Of Thermal Barrier Coatings For Aero-Propulsion Applications, Brian Hazel, Michael J. Maloney

Thermal Barrier Coatings IV

Thermal barrier coatings for aero-propulsion operation have been in use since the 1960s. These thermal barrier coatings are composed of an oxidation resistant metallic base layer and a thermally resistant ceramic top layer. The development and implementation of advances in both the metallic base and the ceramic top layer will be explored. The evolution has included performance and durability improvements, process advances, and understanding and evolution of failure modes. More recent efforts have focus on future challenges for thermal barrier coatings to meet ever increasing operating temperature demands of future applications.

Potential Impacts Of Alternative Fuels On The Evolution And Stability Of Turbine Hot- Section Materials, Daniel Mumm, Timothy Montalbano, Matthew Sullivan

Thermal Barrier Coatings IV

This talk will provide an overview of a research program focused on evaluating the potential impacts of alternative fuels (coal-derived syngas, high-hydrogen content fuels, bio-derived synthetics) on the degradation of hot-section materials through accelerated attack of protective thermally grown oxides (TGOs) and thermal barrier coating (TBC) systems. A primary focus is the role of elevated water vapor levels, volatility, and vapor phase transport processes on the evolution of TGO and TBC systems. Materials exposure studies will be described that demonstrate that differing simulated combustion environments affect both the growth rate and the stability of the resulting thermally grown oxides. In …

On The Behavior Of Titanium Within Thermal Barrier Coatings And Its Influence On Residual Stress Within The Tgo, Robbie J. Bennett, Ian Edmonds, Neil Jones, Catherine Rae

Thermal Barrier Coatings IV

This research focuses on analysing the interaction between three commercially used diffusion coatings and a nickel based superalloy CMSX-4. The coatings applied are alumide, Pt-alumide and Pt-modifed γ/γ′. The research has two main themes, firstly diffusion and secondly oxidation. Results of quantitative EPMA show that titanium diffusion towards the surface varies between coatings, and has a strong correlation with the use of platinum within coatings. The concentrations of Ti within Pt-aluminide coatings after 100 hours oxidation in air at 1100°C were found to be twice as high as those within the plain aluminised CMSX-4 samples. Furthermore uphill diffusion of Ti …

The Effect Of Environment And Superalloy Composition On Tbc Lifetime, Bruce Pint, Kinga Unocic, Michael Lance, J. Allen Haynes

Thermal Barrier Coatings IV

While the water vapor content of the combustion gas in natural gas-fired land based turbines is ~10%, it can be 20-85% with coal-derived (syngas or H2) fuels or innovative turbine concepts for more efficient carbon capture. Additional concepts envisage working fluids with high CO2 contents to facilitate carbon capture and sequestration. Also, for land-based, power-generation turbines, there is industry interest in reducing alloy costs by decreasing the superalloy Re content, either by developing new alloys or employing earlier generation superalloys. To investigate the effects of these variables on thermal barrier coating (TBC) lifetime, furnace cycling tests (1h cycles) were performed …

High-Temperature Ceramic Coatings Used In Aero Engine Environments, David Rickerby, Paul Morrell, Matthew Hancock

Thermal Barrier Coatings IV

This paper reviews the role of ceramic coatings technology in the hot sections of modern gas turbine engines by contrasting the role of surface engineering and coatings away from secondary reliance (i.e. the coating extending the life of the component and when the coating is lost or fails there is still an appreciable remnant life of the component) to prime reliance where the failure of the coating would result in a rapid failure of the component. To illustrate this change in design philosophy, the coating systems deployed in the HP turbine module in both shrouded and unshrouded configurations are discussed …

Fate And Transport Of Nanohybrids In Subsurface Media For Oil Field Applications, M.J. Kadhum, D.P. Swatske, J.H. Harwell, D.E. Resasco, B.J. Shiau

5th International Conference on Porous Media and Their Applications in Science, Engineering and Industry

Interfacially active carbon nanotube hybrids have potential to be used in reservoir development applications. Carbon nanotubes hybrids (CNT) can act as carriers for catalytic nanoparticles into regions far inside the reservoir; they have the ability to stabilize water/oil interface in emulsions or can be used as contrast agents or sensors. One of the main challenges for successful utilization of these nanoparticles is the difficulty associated with stabilizing their dispersions and propagating them through the wellbore rock or deep inside the reservoir in harsh reservoir conditions of salinity and temperature. In this work, CNT were dispersed in high salinity brine using …