Performance Evaluation and Opportunity Assessment for St. Bernard Project (open access)

Performance Evaluation and Opportunity Assessment for St. Bernard Project

This report describes efforts by IBACOS, a Department of Energy Building America research team, in the St. Bernard Project, a nonprofit, community-based organization whose mission is to assist Hurricane Katrina survivors return to their homes in the New Orleans area. The report focuses on energy modeling results of two plans that the St. Bernard Project put forth as 'typical' building types and on quality issues that were observed during the field walk and Best Practice recommendations that could improve the energy efficiency and durability of the renovated homes.
Date: June 1, 2011
Creator: Dickson, B.
Object Type: Report
System: The UNT Digital Library
Wakefield Calculations for the LCLS in Multbunch Operation (open access)

Wakefield Calculations for the LCLS in Multbunch Operation

Normally the Linac Coherent Light Source (LCLS) operates in single-bunch mode, sending a bunch of up to 250 pC charge at 120 Hz through the linac and the undulator, and the resulting FEL radiation into one of the experimental hutches. With two bunches per rf pulse, each pulse could feed either two experiments or one experiment in a pump-probe type configuration. Two-bunch FEL operation has already been briefly tested at the LCLS, and works reasonably well, although not yet routinely. In this report we study the longitudinal and transverse long-range (bunch-to-bunch) wakefields of the linacs and their effects on LCLS performance in two-bunch mode, which is initially the most likely scenario. The longitudinal wake changes the average energy at the second bunch, and the transverse wake misaligns the second bunch (in transverse phase space) in the presence of e.g. transverse injection jitter or quad misalignments. Finally, we extend the study to consider the LCLS with trains of up to 20 bunches per rf pulse. In the LCLS the bunch is created in an rf gun, and then passes in sequence through Linac 0, Linac 1, Linac X, Bunch Compressor 1 (BC 1), Linac 2, BC 2, Linac 3, and finally …
Date: October 17, 2011
Creator: Bane, K.
Object Type: Article
System: The UNT Digital Library
Melting Hanford LAW into Iron-Phosphate Glass in a CCIM (open access)

Melting Hanford LAW into Iron-Phosphate Glass in a CCIM

A vitrification test has been conducted using the cold crucible induction melter (CCIM) test system at the Idaho National Laboratory. The test was conducted to demonstrate the vitrification of a Hanford low activity waste (LAW) that contains relatively large amounts of sulfate and sodium, compared to other radioactive Hanford waste streams. The high sulfate content limits the potential loading of this waste stream in conventional borosilicate glass, so this test demonstrated how this waste stream could be vitrified in an iron-phosphate glass that can tolerate higher levels of sulfate.
Date: September 1, 2011
Creator: Soelberg, Nick & Rossberg, Sharna
Object Type: Report
System: The UNT Digital Library
The Role of Eddy-Tansport in the Thermohaline Circulation (open access)

The Role of Eddy-Tansport in the Thermohaline Circulation

Several research themes were developed during the course of this project. (1) Low-frequency oceanic varibility; (2) The role of eddies in the Antarctic Circumpolar Current (ACC) region; (3) Deep stratification and the overturning circulation. The key findings were as follows: (1) The stratification below the main thermocline (at about 500m) is determined in the circumpolar region and then communicated to the enclosed portions of the oceans through the overturning circulation. (2) An Atlantic pole-to-pole overturning circulation can be maintained with very small interior mixing as long as surface buoyancy values are shared between the northern North Atlantic and the ACC region.
Date: November 17, 2011
Creator: Cessi, Dr. Paola
Object Type: Report
System: The UNT Digital Library
A Hierarchical Security Architecture for Cyber-Physical Systems (open access)

A Hierarchical Security Architecture for Cyber-Physical Systems

Security of control systems is becoming a pivotal concern in critical national infrastructures such as the power grid and nuclear plants. In this paper, we adopt a hierarchical viewpoint to these security issues, addressing security concerns at each level and emphasizing a holistic cross-layer philosophy for developing security solutions. We propose a bottom-up framework that establishes a model from the physical and control levels to the supervisory level, incorporating concerns from network and communication levels. We show that the game-theoretical approach can yield cross-layer security strategy solutions to the cyber-physical systems.
Date: August 1, 2011
Creator: Zhu, Quanyan & Basar, Tamer
Object Type: Article
System: The UNT Digital Library
Section on Supernova Remnants and Cosmic Rays of the White Paper on the Status and Future of Ground-Based Gamma-Ray Astronomy (open access)

Section on Supernova Remnants and Cosmic Rays of the White Paper on the Status and Future of Ground-Based Gamma-Ray Astronomy

This is a report on the findings of the SNR/cosmic-ray working group for the white paper on the status and future of ground-based gamma-ray astronomy. The white paper is an APS commissioned document, and the overall version has also been released and can be found on astro-ph. This detailed section of the white paper discusses the status of past and current attempts to observe shell-type supernova remnants and diffuse emission from cosmic rays at GeV-TeV energies. We concentrate on the potential of future ground-based gamma-ray experiments to study the acceleration of relativistic charged particles which is one of the main unsolved, yet fundamental, problems in modern astrophysics. The acceleration of particles relies on interactions between energetic particles and magnetic turbulence. In the case of SNRs we can perform spatially resolved studies in systems with known geometry, and the plasma physics deduced from these observations will help us to understand other systems where rapid particle acceleration is believed to occur and where observations as detailed as those of SNRs are not possible.
Date: November 9, 2011
Creator: Pohl, M.; U., /Iowa State; Abdo, Aous A.; U., /Michigan State; Atoyan, A.; U., /McGill et al.
Object Type: Report
System: The UNT Digital Library
Density Functional Theory in Surface Chemistry and Catalysis (open access)

Density Functional Theory in Surface Chemistry and Catalysis

Recent advances in the understanding of reactivity trends for chemistry at transition metal surfaces have enabled in silico design of heterogeneous catalysts in a few cases. Current status of the field is discussed with an emphasis on the role of coupling between theory and experiment and future challenges.
Date: May 19, 2011
Creator: Norskov, Jens
Object Type: Article
System: The UNT Digital Library
Supply Chain Based Solution to Prevent Fuel Tax Evasion: Proof of Concept Final Report (open access)

Supply Chain Based Solution to Prevent Fuel Tax Evasion: Proof of Concept Final Report

The goal of this research was to provide a proof-of-concept (POC) system for preventing non-taxable (non-highway diesel use) or low-taxable (jet fuel) petrochemical products from being blended with taxable fuel products and preventing taxable fuel products from cross-jurisdiction evasion. The research worked to fill the need to validate the legitimacy of individual loads, offloads, and movements by integrating and validating, on a near-real-time basis, information from global positioning system (GPS), valve sensors, level sensors, and fuel-marker sensors.
Date: December 1, 2011
Creator: Capps, Gary J.; Lascurain, Mary Beth; Franzese, Oscar; Earl, Dennis Duncan; West, David L.; McIntyre, Timothy J. et al.
Object Type: Report
System: The UNT Digital Library
High efficiency multilayer blazed gratings for EUV and soft X-rays: Recent developments (open access)

High efficiency multilayer blazed gratings for EUV and soft X-rays: Recent developments

Multilayer coated blazed gratings with high groove density are the best candidates for use in high resolution EUV and soft x-ray spectroscopy. Theoretical analysis shows that such a grating can be potentially optimized for high dispersion and spectral resolution in a desired high diffraction order without significant loss of diffraction efficiency. In order to realize this potential, the grating fabrication process should provide a perfect triangular groove profile and an extremely smooth surface of the blazed facets. Here we report on recent progress achieved at the Advanced Light Source (ALS) in fabrication of high quality multilayer coated blazed gratings. The blazed gratings were fabricated using scanning beam interference lithography followed by wet anisotropic etching of silicon. A 200 nm period grating coated with a Mo/Si multilayer composed with 30 bi-layers demonstrated an absolute efficiency of 37.6percent in the 3rd diffraction order at 13.6 nm wavelength. The groove profile of the grating was thoroughly characterized with atomic force microscopy before and after the multilayer deposition. The obtained metrology data were used for simulation of the grating efficiency with the vector electromagnetic PCGrate-6.1 code. The simulations showed that smoothing of the grating profile during the multilayer deposition is the main reason for …
Date: July 26, 2011
Creator: Voronov, Dmitriy; Ahn, Minseung; Anderson, Erik; Cambie, Rossana; Chang, Chih-Hao; Goray, Leonid et al.
Object Type: Article
System: The UNT Digital Library
TESTING OF ENHANCED CHEMICAL CLEANING OF SRS ACTUAL WASTE TANK 5F AND TANK 12H SLUDGES (open access)

TESTING OF ENHANCED CHEMICAL CLEANING OF SRS ACTUAL WASTE TANK 5F AND TANK 12H SLUDGES

Forty three of the High Level Waste (HLW) tanks at the Savannah River Site (SRS) have internal structures that hinder removal of the last approximately five thousand gallons of waste sludge solely by mechanical means. Chemical cleaning can be utilized to dissolve the sludge heel with oxalic acid (OA) and pump the material to a separate waste tank in preparation for final disposition. This dissolved sludge material is pH adjusted downstream of the dissolution process, precipitating the sludge components along with sodium oxalate solids. The large quantities of sodium oxalate and other metal oxalates formed impact downstream processes by requiring additional washing during sludge batch preparation and increase the amount of material that must be processed in the tank farm evaporator systems and the Saltstone Processing Facility. Enhanced Chemical Cleaning (ECC) was identified as a potential method for greatly reducing the impact of oxalate additions to the SRS Tank Farms without adding additional components to the waste that would extend processing or increase waste form volumes. In support of Savannah River Site (SRS) tank closure efforts, the Savannah River National Laboratory (SRNL) conducted Real Waste Testing (RWT) to evaluate an alternative to the baseline 8 wt. % OA chemical cleaning …
Date: August 22, 2011
Creator: Martino, C. & King, W.
Object Type: Report
System: The UNT Digital Library
Scientific Grand Challenges: Crosscutting Technologies for Computing at the Exascale - February 2-4, 2010, Washington, D.C. (open access)

Scientific Grand Challenges: Crosscutting Technologies for Computing at the Exascale - February 2-4, 2010, Washington, D.C.

The goal of the "Scientific Grand Challenges - Crosscutting Technologies for Computing at the Exascale" workshop in February 2010, jointly sponsored by the U.S. Department of Energy’s Office of Advanced Scientific Computing Research and the National Nuclear Security Administration, was to identify the elements of a research and development agenda that will address these challenges and create a comprehensive exascale computing environment. This exascale computing environment will enable the science applications identified in the eight previously held Scientific Grand Challenges Workshop Series.
Date: February 6, 2011
Creator: Khaleel, Mohammad A.
Object Type: Report
System: The UNT Digital Library
REACTOR GROUT THERMAL PROPERTIES (open access)

REACTOR GROUT THERMAL PROPERTIES

Savannah River Site has five dormant nuclear production reactors. Long term disposition will require filling some reactor buildings with grout up to ground level. Portland cement based grout will be used to fill the buildings with the exception of some reactor tanks. Some reactor tanks contain significant quantities of aluminum which could react with Portland cement based grout to form hydrogen. Hydrogen production is a safety concern and gas generation could also compromise the structural integrity of the grout pour. Therefore, it was necessary to develop a non-Portland cement grout to fill reactors that contain significant quantities of aluminum. Grouts generate heat when they set, so the potential exists for large temperature increases in a large pour, which could compromise the integrity of the pour. The primary purpose of the testing reported here was to measure heat of hydration, specific heat, thermal conductivity and density of various reactor grouts under consideration so that these properties could be used to model transient heat transfer for different pouring strategies. A secondary purpose was to make qualitative judgments of grout pourability and hardened strength. Some reactor grout formulations were unacceptable because they generated too much heat, or started setting too fast, or required …
Date: January 28, 2011
Creator: Steimke, J.; Qureshi, Z.; Restivo, M. & Guerrero, H.
Object Type: Report
System: The UNT Digital Library
RESULTS FOR THE FOURTH QUARTER 2010 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS (open access)

RESULTS FOR THE FOURTH QUARTER 2010 TANK 50 WAC SLURRY SAMPLE: CHEMICAL AND RADIONUCLIDE CONTAMINANT RESULTS

This report details the chemical and radionuclide contaminant results for the characterization of the 2010 Fourth Quarter sampling of Tank 50 for the Saltstone Waste Acceptance Criteria (WAC). Information from this characterization will be used by Liquid Waste Operations (LWO) to support the transfer of low-level aqueous waste from Tank 50 to the Salt Feed Tank in the Saltstone Facility in Z-Area, where the waste will be immobilized. This information is also used to update the Tank 50 Waste Characterization System. The following conclusions are drawn from the analytical results provided in this report: (1) The concentrations of the reported chemical and radioactive contaminants were less than their respective WAC targets or limits unless noted in this section. (2) The reported detection limits for {sup 94}Nb, {sup 247}Cm and {sup 249}Cf are above the requested limits from Reference 2. However, they are below the limits established in Reference 3. (3) There is an estimated concentration of trimethylbenzene (2.25 mg/L). This is not a WAC analyte, but it is the first time this organic compound has been detected in a quarterly WAC sample from Tank 50. (4) The reported detection limit for Norpar 13 is greater than the limit from Table …
Date: February 22, 2011
Creator: Reigel, M.
Object Type: Report
System: The UNT Digital Library
Hydrogen Production Cost Estimate Using Biomass Gasification: Independent Review (open access)

Hydrogen Production Cost Estimate Using Biomass Gasification: Independent Review

This independent review is the conclusion arrived at from data collection, document reviews, interviews and deliberation from December 2010 through April 2011 and the technical potential of Hydrogen Production Cost Estimate Using Biomass Gasification. The Panel reviewed the current H2A case (Version 2.12, Case 01D) for hydrogen production via biomass gasification and identified four principal components of hydrogen levelized cost: CapEx; feedstock costs; project financing structure; efficiency/hydrogen yield. The panel reexamined the assumptions around these components and arrived at new estimates and approaches that better reflect the current technology and business environments.
Date: October 1, 2011
Creator: Ruth, M.
Object Type: Report
System: The UNT Digital Library
New HOM coupler design for high current SRF cavity (open access)

New HOM coupler design for high current SRF cavity

Damping higher order modes (HOMs) significantly to avoid beam instability is a challenge for the high current Energy Recovery Linac-based eRHIC at BNL. To avoid the overheating effect and high tuning sensitivity, current, a new band-stop HOM coupler is being designed at BNL. The new HOM coupler has a bandwidth of tens of MHz to reject the fundamental mode, which will avoid overheating due to fundamental frequency shifting because of cooling down. In addition, the S21 parameter of the band-pass filter is nearly flat from first higher order mode to 5 times the fundamental frequency. The simulation results showed that the new couplers effectively damp HOMs for the eRHIC cavity with enlarged beam tube diameter and 2 120{sup o} HOM couplers at each side of cavity. This paper presents the design of HOM coupler, HOM damping capacity for eRHIC cavity and prototype test results.
Date: March 28, 2011
Creator: Xu, W.; Ben-Zvi, Ilan; Belomestnykh, S.; Hahn, H. & Johnson, E.
Object Type: Article
System: The UNT Digital Library
Aligned mesoporous architectures and devices. (open access)

Aligned mesoporous architectures and devices.

This is the final report for the Presidential Early Career Award for Science and Engineering - PECASE (LDRD projects 93369 and 118841) awarded to Professor Yunfeng Lu (Tulane University and University of California-Los Angeles). During the last decade, mesoporous materials with tunable periodic pores have been synthesized using surfactant liquid crystalline as templates, opening a new avenue for a wide spectrum of applications. However, the applications are somewhat limited by the unfavorabe pore orientation of these materials. Although substantial effort has been devoted to align the pore channels, fabrication of mesoporous materials with perpendicular pore channels remains challenging. This project focused on fabrication of mesoporous materials with perpendicularly aligned pore channels. We demonstrated structures for use in water purification, separation, sensors, templated synthesis, microelectronics, optics, controlled release, and highly selective catalysts.
Date: March 1, 2011
Creator: Brinker, C. Jeffrey & Lu, Yunfeng (University of California Los Angeles, Los Angeles, CA)
Object Type: Report
System: The UNT Digital Library
A Study of undulator magnets characterization using the Vibrating Wire technique (open access)

A Study of undulator magnets characterization using the Vibrating Wire technique

The vibrating wire (VW) technique employs a stretched wire as a magnetic field sensor. Because of the wire's small diameter ({approx}0.1mm or smaller) and because the wire can be supported from outside the magnet, this technique is very appealing for field measurements in small gap/bore undulators with small good field regions and with limited access to the tested field. In addition, in the case of elliptical undulators in which Hall probe (HP) measurements can be affected by the planar Hall effect, VW technique can be used as an independent method to verify and supplement HP measurements. In this article we studied the potential of the VW technique for measurement of magnetic field errors and for prediction of beam trajectories in undulator magnets using a 3.8m long LCLS undulator as a test bench. Introducing calibrated magnetic field distortion at various locations, we measured the sensitivity and spatial resolution of the method. The method demonstrated 0.9mm spatial resolution at a distance up to a few meters and 0.37Gcm sensitivity to the field integral. To compare Hall probe and Vibrating wire measurements side-by-side, we measured field errors in an LCLS undulator previously characterized by Hall probe measurements. The field errors found with the …
Date: February 7, 2011
Creator: Temnykh, Alexander; Levashov, Yurii & Wolf, Zachary
Object Type: Report
System: The UNT Digital Library
Neutrino-nucleus interactions (open access)

Neutrino-nucleus interactions

The study of neutrino oscillations has necessitated a new generation of neutrino experiments that are exploring neutrino-nuclear scattering processes. We focus in particular on charged-current quasi-elastic scattering, a particularly important channel that has been extensively investigated both in the bubble-chamber era and by current experiments. Recent results have led to theoretical reexamination of this process. We review the standard picture of quasi-elastic scattering as developed in electron scattering, review and discuss experimental results, and discuss additional nuclear effects such as exchange currents and short-range correlations that may play a significant role in neutrino-nucleus scattering.
Date: January 1, 2011
Creator: Gallagher, H.; Garvey, G. & Zeller, G. P.
Object Type: Article
System: The UNT Digital Library
Membranes and surfaces nano-engineered for pathogen capture and destruction. (open access)

Membranes and surfaces nano-engineered for pathogen capture and destruction.

None
Date: December 1, 2011
Creator: Nyman, May Devan & Stewart, Thomas Austin
Object Type: Report
System: The UNT Digital Library
2011 Archaea: Ecology, Metabolism, & Molecular Biology (open access)

2011 Archaea: Ecology, Metabolism, & Molecular Biology

Archaea, one of three major evolutionary lineages of life, are a fascinating and diverse group of microbes with deep roots overlapping those of eukaryotes. The focus of the 'Archaea: Ecology Metabolism & Molecular Biology' GRC conference expands on a number of emerging topics highlighting new paradigms in archaeal metabolism, genome function and systems biology; information processing; evolution and the tree of life; the ecology and diversity of archaea and their viruses. The strength of this conference lies in its ability to couple a field with a rich history in high quality research with new scientific findings in an atmosphere of stimulating exchange. This conference remains an excellent opportunity for younger scientists to interact with world experts in this field.
Date: August 5, 2011
Creator: Stedman, Keneth
Object Type: Article
System: The UNT Digital Library
Catalytic Process for the Conversion of Coal-derived Syngas to Ethanol (open access)

Catalytic Process for the Conversion of Coal-derived Syngas to Ethanol

The catalytic conversion of coal-derived syngas to C{sub 2+} alcohols and oxygenates has attracted great attention due to their potential as chemical intermediates and fuel components. This is particularly true of ethanol, which can serve as a transportation fuel blending agent, as well as a hydrogen carrier. A thermodynamic analysis of CO hydrogenation to ethanol that does not allow for byproducts such as methane or methanol shows that the reaction: 2 CO + 4 H{sub 2} {yields} C{sub 2}H{sub 5}OH + H{sub 2}O is thermodynamically favorable at conditions of practical interest (e.g,30 bar, {approx}< 250 C). However, when methane is included in the equilibrium analysis, no ethanol is formed at any conditions even approximating those that would be industrially practical. This means that undesired products (primarily methane and/or CO{sub 2}) must be kinetically limited. This is the job of a catalyst. The mechanism of CO hydrogenation leading to ethanol is complex. The key step is the formation of the initial C-C bond. Catalysts that are selective for EtOH can be divided into four classes: (a) Rh-based catalysts, (b) promoted Cu catalysts, (c) modified Fischer-Tropsch catalysts, or (d) Mo-sulfides and phosphides. This project focuses on Rh- and Cu-based catalysts. The logic …
Date: July 29, 2011
Creator: Spivery, James; Harrison, Doug; Earle, John; Goodwin, James; Bruce, David; Mo, Xunhau et al.
Object Type: Report
System: The UNT Digital Library
Reducing Data Center Loads for a Large-Scale, Low-Energy Office Building: NREL's Research Support Facility (Book) (open access)

Reducing Data Center Loads for a Large-Scale, Low-Energy Office Building: NREL's Research Support Facility (Book)

This publication detailing the design, implementation strategies, and continuous performance monitoring of NREL's Research Support Facility data center. Data centers are energy-intensive spaces that facilitate the transmission, receipt, processing, and storage of digital data. These spaces require redundancies in power and storage, as well as infrastructure, to cool computing equipment and manage the resulting waste heat (Tschudi, Xu, Sartor, and Stein, 2003). Data center spaces can consume more than 100 times the energy of standard office spaces (VanGeet 2011). The U.S. Environmental Protection Agency (EPA) reported that data centers used 61 billion kilowatt-hours (kWh) in 2006, which was 1.5% of the total electricity consumption in the U.S. (U.S. EPA, 2007). Worldwide, data centers now consume more energy annually than Sweden (New York Times, 2009). Given their high energy consumption and conventional operation practices, there is a potential for huge energy savings in data centers. The National Renewable Energy Laboratory (NREL) is world renowned for its commitment to green building construction. In June 2010, the laboratory finished construction of a 220,000-square-foot (ft{sup 2}), LEED Platinum, Research Support Facility (RSF), which included a 1,900-ft{sup 2} data center. The RSF will expand to 360,000 ft{sup 2} with the opening of an additional wing …
Date: December 1, 2011
Creator: Sheppy, M.; Lobato, C.; Van Geet, O.; Pless, S.; Donovan, K. & Powers, C.
Object Type: Report
System: The UNT Digital Library
OECD MCCI project Melt Eruption Test (MET) design report, Rev. 2. April 15, 2003. (open access)

OECD MCCI project Melt Eruption Test (MET) design report, Rev. 2. April 15, 2003.

The Melt Attack and Coolability Experiments (MACE) program at Argonne National Laboratory addressed the issue of the ability of water to cool and thermally stabilize a molten core-concrete interaction when the reactants are flooded from above. These tests provided data regarding the nature of corium interactions with concrete, the heat transfer rates from the melt to the overlying water pool, and the role of noncondensable gases in the mixing processes that contribute to melt quenching. The Melt Coolability and Concrete Interaction (MCCI) program is pursuing separate effect tests to examine the viability of the melt coolability mechanisms identified as part of the MACE program. These mechanisms include bulk cooling, water ingression, volcanic eruptions, and crust breach. At the second PRG meeting held at ANL on 22-23 October 2002, a preliminary design1 for a separate effects test to investigate the melt eruption cooling mechanism was presented for PRG review. At this meeting, NUPEC made several recommendations on the experiment approach aimed at optimizing the chances of achieving a floating crust boundary condition in this test. The principal recommendation was to incorporate a mortar sidewall liner into the test design, since data from the COTELS experiment program indicates that corium does not …
Date: May 23, 2011
Creator: Farmer, M. T.; Lomperski, S.; Kilsdonk, D. J.; Aeschlimann, R. W. & Basu, S.
Object Type: Report
System: The UNT Digital Library
LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE (open access)

LONG-TERM PERFORMANCE OF SOLID OXIDE STACKS WITH ELECTRODE-SUPPORTED CELLS OPERATING IN THE STEAM ELECTROLYSIS MODE

Performance characterization and durability testing have been completed on two five-cell high-temperature electrolysis stacks constructed with advanced cell and stack technologies. The solid oxide cells incorporate a negative-electrode-supported multi-layer design with nickel-zirconia cermet negative electrodes, thin-film yttria-stabilized zirconia electrolytes, and multi-layer lanthanum ferrite-based positive electrodes. The per-cell active area is 100 cm2. The stack is internally manifolded with compliant mica-glass seals. Treated metallic interconnects with integral flow channels separate the cells. Stack compression is accomplished by means of a custom spring-loaded test fixture. Initial stack performance characterization was determined through a series of DC potential sweeps in both fuel cell and electrolysis modes of operation. Results of these sweeps indicated very good initial performance, with area-specific resistance values less than 0.5 ?.cm2. Long-term durability testing was performed with A test duration of 1000 hours. Overall performance degradation was less than 10% over the 1000-hour period. Final stack performance characterization was again determined by a series of DC potential sweeps at the same flow conditions as the initial sweeps in both electrolysis and fuel cell modes of operation. A final sweep in the fuel cell mode indicated a power density of 0.356 W/cm2, with average per-cell voltage of 0.71 V at …
Date: November 1, 2011
Creator: O'Brien, J. E.; O'Brien, R. C.; Zhang, X.; Tao, G. & Butler, B. J.
Object Type: Article
System: The UNT Digital Library