Early Inflation and Cosmology in Theories with Sub-Millimeter Dimensions (open access)

Early Inflation and Cosmology in Theories with Sub-Millimeter Dimensions

We discuss early cosmology in theories where the fundamental Planck mass is close to the TeV scale. In such theories the standard model fields are localized to a (3 + 1)-dimensional wall with n new transverse sub-millimeter sized spatial dimensions. The topics touched upon include: early inflation that occurs while the size of the new dimensions are still small, the spectrum and magnitude of density perturbations, the post-inflation era of contraction of our world while the internal dimensions evolve to their final ''large'' radius, and the production of gravitons in the bulk during these two eras. The radion moduli problem is also discussed.
Date: March 15, 1999
Creator: Arkani-Hamed, Nima
Object Type: Report
System: The UNT Digital Library
Probing excited states in nuclei at and beyond the proton dripline. (open access)

Probing excited states in nuclei at and beyond the proton dripline.

The coupling of a Compton-suppressed Ge (CSGe) detector array to a recoil separator has seen limited use in the past due to the low efficiency for measuring recoil--{gamma} ray coincidences (< 0.1%). With the building of new generation recoil separators and gamma-ray arrays, a substantial increase in detection efficiency has been achieved. This allows for the opportunity to measure excited states in nuclei with cross-sections below 100 nb. In this paper, results from the coupling of a modest array of CSGe detectors (AYE-Ball) and a current generation Ge array (Gammasphere) with a recoil separator (FMA) will be presented.
Date: March 15, 1999
Creator: Carpenter, M. P.
Object Type: Article
System: The UNT Digital Library
Technical progress report during Phase 1 of the continuous fiber ceramic composites program (open access)

Technical progress report during Phase 1 of the continuous fiber ceramic composites program

United States industry has a critical need for materials that are lightweight, strong, tough, corrosion resistant and capable of performing at high temperatures; such materials will enable substantial increase in energy efficiency and reduction in emissions of pollutants. Continuous fiber ceramic composites (CFCCs) are an emerging class of materials which have the potential for the desired combination of properties to meet the industrial needs. A $10 billion annual market has been estimated for CFCC products by the year 2010, which equates to over 100,000 industrial sector jobs. The CFCC program began in the spring of 1992 as a three-phase 10-year effort to assess potential applications of CFCC materials, develop the necessary supporting technologies to design, analyze and test CFCC materials, conduct materials and process development guided by the applications assessment input, fabricate test samples and representative components to evaluate CFCC material capabilities under application conditions, and analyze scaleability and manufacturability plus demonstrate pilot-scale production engineering. DOE awarded 10 Phase I cooperative agreements to industry-lead teams plus identified generic supporting technology projects. This document highlights the broad progress and accomplishments on these contracts and support technology projects during Phase I.
Date: March 15, 1994
Creator: Richerson, David W.
Object Type: Report
System: The UNT Digital Library
Physics of collisionless scrape-off-layer plasma during normal and off-normal Tokamak operating conditions. (open access)

Physics of collisionless scrape-off-layer plasma during normal and off-normal Tokamak operating conditions.

The structure of a collisionless scrape-off-layer (SOL) plasma in tokamak reactors is being studied to define the electron distribution function and the corresponding sheath potential between the divertor plate and the edge plasma. The collisionless model is shown to be valid during the thermal phase of a plasma disruption, as well as during the newly desired low-recycling normal phase of operation with low-density, high-temperature, edge plasma conditions. An analytical solution is developed by solving the Fokker-Planck equation for electron distribution and balance in the SOL. The solution is in good agreement with numerical studies using Monte-Carlo methods. The analytical solutions provide an insight to the role of different physical and geometrical processes in a collisionless SOL during disruptions and during the enhanced phase of normal operation over a wide range of parameters.
Date: March 15, 1999
Creator: Hassanein, A. & Konkashbaev, I.
Object Type: Report
System: The UNT Digital Library
The FEL development at the Advanced Photon Source. (open access)

The FEL development at the Advanced Photon Source.

Construction of a single-pass free-electron laser (FEL) based on the self-amplified spontaneous emission (SASE) mode of operation is nearing completion at the Advanced Photon Source (APS) with initial experiments imminent. The APS SASE FEL is a proof-of-principle fourth-generation light source. As of January 1999 the undulator hall, end-station building, necessary transfer lines, electron and optical diagnostics, injectors, and initial undulatory have been constructed and, with the exception of the undulatory, installed. All preliminary code development and simulations have also been completed. The undulator hall is now ready to accept first beam for characterization of the output radiation. It is the project goal to push towards fill FEL saturation, initially in the visible, but ultimately to W and VUV, wavelengths.
Date: March 15, 1999
Creator: Arnold, N. D.; Benson, C.; Berg, S.; Berg, W.; Biedron, S. G.; Chae, Y. C. et al.
Object Type: Article
System: The UNT Digital Library
Design Optimization and Construction of the Thyratron/PFN Based Cost Model Modulator for the NLC (open access)

Design Optimization and Construction of the Thyratron/PFN Based Cost Model Modulator for the NLC

As design studies and various R and D efforts continue on Next Linear Collider (NLC) systems, much R and D work is being done on X-Band klystron development, and development of pulse modulators to drive these X-Band klystrons. A workshop on this subject was held at SLAC in June of 1998, and a follow-up workshop is scheduled at SLAC June 23-25, 1999. At the 1998 workshop, several avenues of R and D were proposed using solid state switching, induction LINAC principles, high voltage hard tubes, and a few more esoteric ideas. An optimized version of the conventional thyratron-PFN-pulse transformer modulator for which there is extensive operating experience is also a strong candidate for use in the NLC. Such a modulator is currently under construction for base line demonstration purposes. The performance of this ''Cost Model'' modulator will be compared to other developing technologies. Important parameters including initial capital cost, operating maintenance cost, reliability, maintainability, power efficiency, in addition to the usual operating parameters of pulse flatness, timing and pulse height jitter, etc. will be considered in the choice of a modulator design for the NLC. This paper updates the progress on this ''Cost Model'' modulator design and construction.
Date: March 15, 1999
Creator: Koontz, Roland F
Object Type: Report
System: The UNT Digital Library
Exploiting the power of DSM and SMP clusters for parallel CFD (open access)

Exploiting the power of DSM and SMP clusters for parallel CFD

The new generation of powerful DSM and SMP cluster computers enables simulations of fluid dynamics at sufficient resolution to compute the complex nonlinear interactions of small-scale turbulent motions with a large-scale driving flow. With a new programming model of hierarchical shared memory multitasking, it is possible to exploit these new systems without disrupting the flow of small and medium-sized jobs that makes their existence possible.
Date: March 15, 1999
Creator: Anderson, S. E.; Cohen, R. H.; Curtis, B. C.; Dannevik, W. P.; Dimits, A. M.; Dinge, D. et al.
Object Type: Article
System: The UNT Digital Library
Rapid asymmetric inflation and early cosmology in theories with sub-millimeter dimensions (open access)

Rapid asymmetric inflation and early cosmology in theories with sub-millimeter dimensions

It was recently pointed out that the fundamental Planck mass could be close to the TeV scale with the observed weakness of gravity at long distances being due the existence of new sub-millimeter spatial dimensions. In this picture the standard model fields are localized to a (3+1)-dimensional wall or ''3-brane''. We show that in such theories there exist attractive models of inflation that occur while the size of the new dimensions are still small. We show that it is easy to produce the required number of efoldings, and further that the density perturbations {delta}{rho}/{rho} as measured by COBE can be easily reproduced, both in overall magnitude and in their approximately scale-invariant spectrum. In the minimal approach, the inflaton field is just the moduli describing the size of the internal dimensions, the role of the inflationary potential being played by the stabilizing potential of the internal space. We show that under quite general conditions, the inflationary era is followed by an epoch of contraction of our world on the brane, while the internal dimensions slowly expand to their stabilization radius. We find a set of exact solutions which describe this behavior, generalizing the well-known Kasner solutions. During this phase, the production …
Date: March 15, 1999
Creator: Arkani-Hamed, Nima
Object Type: Report
System: The UNT Digital Library
NONEQUILIBRIUM SULFUR CAPTURE AND RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR (open access)

NONEQUILIBRIUM SULFUR CAPTURE AND RETENTION IN AN AIR COOLED SLAGGING COAL COMBUSTOR

Calcium oxide injected in a slagging combustor reacts with the sulfur from coal combustion to form sulfur-bearing particles. They are deposited on the liquid slag layer on the combustor wall. Due to the low solubility of sulfur in slag, slag must be rapidly drained from the combustor to limit sulfur gas re-evolution. Analysis indicated that slag mass flow rates in excess of 400 lb/hr should limit sulfur re-evolution. The objective of this 42-month project was to perform a series of tests to determine the factors that control the retention of the sulfur in the slag. 36 days of testing on the combustor were completed prior to the end of this reporting period, 12/31/98. This compares with 16 tests required in the original project plan. Combustor tests in early 1997 with high (37%) ash, Indian coal confirmed that high slag mass flow rates of about 500 lb/hr resulted in retention in the slag of up to 20% of the injected sulfur content mineral matter. To further increase the slag flow rate, rice husks, which contain 20% ash, and rice husk char, which contain 70% ash, were co-fired with coal in the combustor. A series of 13 combustor tests were performed in …
Date: March 15, 1999
Creator: Zauderer, Dr. Bert
Object Type: Report
System: The UNT Digital Library
Kinetics of Mn-based sorbents for hot coal gas desulfurization. Task 2 -- Exploratory experimental studies: Single pellet tests; rate mechanism analysis. Quarterly report, December 15, 1995--March 15, 1996 (open access)

Kinetics of Mn-based sorbents for hot coal gas desulfurization. Task 2 -- Exploratory experimental studies: Single pellet tests; rate mechanism analysis. Quarterly report, December 15, 1995--March 15, 1996

Currently, the Morgantown Energy Technology Center, is actively investigating alternative hot fuel gas desulfurization sorbents for application to the Integrated Gasification Combined Cycle (IGCC). A sorbent must be highly active towards sulfur at high temperatures and pressure`s, and under varying degrees of reducing atmospheres. Thus, high conversion of the metal oxide and low hydrogen sulfide exit partial pressures. Also, it must regenerate nearly ideally to maintain activity over numerous cycles. Furthermore, regeneration must yield a sulfur product which is economically recoverable directly or indirectly. This cyclic process requires a holistic approach as any one criteria may eliminate a candidate sorbent from further consideration. Over fifty induration campaigns have been conducted among the fifteens Mn-based sorbent formulations. All indurated sorbents has been tested for crush strength and chemical analysis. Also, fifteen sorbent formulations have been tested in a TGA for at least on e induration condition. Subsequently described are the three main groups of formulations tested. They are the MnCO{sub 3} supported with TiO{sub 2} (with or without bentonite), MnCO{sub 3} supported with Al{sub 2}O{sub 3} (with or without porosity enhancers), and MnO{sub 2} ore supported with alundum (with and without bentonite).
Date: March 15, 1996
Creator: Hepworth, M.T. & Berns, J.
Object Type: Report
System: The UNT Digital Library
Measurement of air quality within storage domes in technical area 54, areas G and L (open access)

Measurement of air quality within storage domes in technical area 54, areas G and L

The concentrations of volatile organic compounds (VOCs) and tritium inside of storage domes at TA-54 were measured to assess worker exposure and support the Area G site characterization, including the Radioactive Air Emissions Management (RAEM) program. Samples were collected at 2-3 locations within Domes 48, 49, and 153 on up to six days during the summer of 1994. Samples were collected to evaluate three scenarios: (1) normal working activities with the domes open; (2) after domes were closed overnight; and (3) after domes were closed for three days. Eight-hour integrated samples were collected and analyzed in Radian`s Austin laboratories. Tritium activities from 17.1 to 69,900 pCi/m{sup 3} were measured. About two dozen individual VOCs were identified in each sample, but most of the concentration levels were very low (e.g.; < 1 to 10 ppbv). The highest concentrations measured were bromomethane (56.5 ppbv), 1, 1,1-trichloroethane (75.4 ppbv), propane (958 ppbv), methylene chloride (1,450 ppbv), and toluene (22.8). The measured VOC concentrations were well below the action levels developed by the New Mexico Environment Department and the measured tritium concentrations were well below the DOE`s derived air concentration (DAC). The variability in concentration within a dome during a single sampling episode was …
Date: March 15, 1994
Creator: Anderson, E.
Object Type: Report
System: The UNT Digital Library
Primate polonium metabolic models and their use in estimation of systemic radiation doses from bioassay data. Final report (open access)

Primate polonium metabolic models and their use in estimation of systemic radiation doses from bioassay data. Final report

A Polonium metabolic model was derived and incorporated into a Fortran algorithm which estimates the systemic radiation dose from {sup 210}Po when applied to occupational urine bioassay data. The significance of the doses estimated are examined by defining the degree of uncertainty attached to them through comprehensive statistical testing procedures. Many parameters necessary for dosimetry calculations (such as organ partition coefficients and excretion fractions), were evaluated from metabolic studies of {sup 210}Po in non-human primates. Two tamarins and six baboons were injected intravenously with {sup 210}Po citrate. Excreta and blood samples were collected. Five of the baboons were sacrificed at times ranging from 1 day to 3 months post exposure. Complete necropsies were performed and all excreta and the majority of all skeletal and tissue samples were analyzed radiochemically for their {sup 210}Po content. The {sup 210}Po excretion rate in the baboon was more rapid than in the tamarin. The biological half-time of {sup 210}Po excretion in the baboon was approximately 15 days while in the tamarin, the {sup 210}Po excretion rate was in close agreement with the 50 day biological half-time predicted by ICRP 30. Excretion fractions of {sup 210}Po in the non-human primates were found to be markedly …
Date: March 15, 1989
Creator: Cohen, N.
Object Type: Report
System: The UNT Digital Library
Ambient monitoring of volatile organic compounds at Los Alamos National Laboratory in technical area 54, areas G and L. Final report (open access)

Ambient monitoring of volatile organic compounds at Los Alamos National Laboratory in technical area 54, areas G and L. Final report

Ambient air monitoring for volatile organic compounds (VOCs) was conducted at TA-54 to characterize non-radioactive air emissions to determine if the Laboratory`s waste operations are releasing significant amounts of VOCs to the ambient environment. Samples were collected at four locations along the northern fenceline (dominant downwind side) of Areas G & L and at a background site located in Bandelier National Monument. Eight-hour integrated samples were collected in evacuated canisters during daylight hours on each of eight days during the summer of 1994, for a total of 40 samples. The samples were analyzed by gas chromatography following EPA Method TO-14 for a target list of 68 analytes. In general, about two dozen volatile organic compounds (VOCs) were identified in each sample, including those collected at the background site, but the concentration levels were very low (e.g.; < 1 to 10 ppbv). The average total non-methane hydrocarbon (TNMHC) concentration ranged from 4.3 to 22.8 ppbv at the Area G and L sites as compared with an average of 4.2 ppbv at the background site. The measured concentrations were compared with action levels developed by the New Mexico Environment Department and were well below the action levels in all cases. Methanol and …
Date: March 15, 1994
Creator: Mischler, S.; Anderson, E. & Vold, E.L.
Object Type: Report
System: The UNT Digital Library
Immobilization as a route to surplus fissile materials disposition. Revision 1 (open access)

Immobilization as a route to surplus fissile materials disposition. Revision 1

The safe management of surplus weapons plutonium is a very important and urgent task with profound environmental, national and international security implications. In the aftermath of the Cold War, Presidential Police Directive 13 and various analysis by renown scientific, technical and international policy organizations have brought about a focused effort within the Department of Energy to identify and implement paths forward for the long term disposition of surplus weapons usable plutonium. The central, overarching goal is to render surplus weapons plutonium as inaccessible and unattractive for reuse in nuclear weapons, as the much larger and growing stock of plutonium contained in civilian spent reactor fuel. One disposition alternative considered for surplus Pu is immobilization, in which plutonium would be emplaced in glass, ceramic or glass-bonded zeolite. This option, along with some of the progress over the last year is discussed.
Date: March 15, 1996
Creator: Gray, L.W.; Kan, T. & McKibben, J.M.
Object Type: Article
System: The UNT Digital Library
Macroscopic traffic modeling with the finite difference method (open access)

Macroscopic traffic modeling with the finite difference method

A traffic congestion forecasting model (ATOP), developed in the present investigation, is described briefly. Several macroscopic models, based on the solution of the partial differential equation of conservation of vehicles by the finite difference method, were tested using actual traffic data. The functional form, as well as the parameters, of the equation of state which describes the relation between traffic speed and traffic density, were determined for a section of the Long Island Expressway. The Lax method and the forward difference technique were applied. The results of extensive tests showed that the Lax method, in addition to giving very good agreement with the traffic data, produces stable solutions.
Date: March 15, 1996
Creator: Mughabghab, S.; Azarm, A. & Stock, D.
Object Type: Report
System: The UNT Digital Library
Observations of comet P/Shoemaker-Levy 9 impact on Jupiter from Lick Obseravtory using a high resolution speckle imaging camera (open access)

Observations of comet P/Shoemaker-Levy 9 impact on Jupiter from Lick Obseravtory using a high resolution speckle imaging camera

During the week of the impacts of Comet Shoemaker-Levy 9 into Jupiter, we used a speckle imaging camera mounted on the Lick Observatory 3 meter Telescope to record a continuous stream of images of the planet. Because the speckle imaging technique compensates for atmospheric blurring, the resulting images were most likely the highest resolution of any taken from the ground. These images compliment the Hubble Space Telescope data by covering time periods when Hubble was not observing Jupiter. We collected full planet 1024 by 1024 pixel CCD images taken 20 per minute for 4 hours per night over 6 nights July 15 to 22. Only a portion of this raw data has been reduced to high resolution images to date.
Date: March 15, 1996
Creator: Max, C.; Gavel, D.; Johansson, E.; Sherwood, B.; Liu, M. & Bradford, B.
Object Type: Report
System: The UNT Digital Library
Measurement of emission fluxes from Technical Area 54, Area G and L. Final report (open access)

Measurement of emission fluxes from Technical Area 54, Area G and L. Final report

The emission flux (mass/time-area) of tritiated water from TA-54 was measured to support the characterization of radioactive air emissions from waste sites for the Radioactive Air Emissions Management (RAEM) program and for the Area G Performance Assessment. Measurements were made at over 180 locations during the summers of 1993 and 1994, including randomly selected locations across Area G, three suspected areas of contamination at Area G, and the property surrounding TA-54. The emission fluxes of radon were measured at six locations and volatile organic compounds (VOCs) at 30 locations. Monitoring was performed at each location over a several-hour period using the U.S. EPA flux chamber approach. Separate samples for tritiated water, radon, and VOCs were collected and analyzed in off-site laboratories. The measured tritiated water emission fluxes varied over several orders of magnitude, from background levels of about 3 pCi/m{sup 2}-min to 9.69 x 10{sup 6} pCi/m{sup 2}-min near a disposal shaft. Low levels of tritiated water were found to have migrated into Pajarito Canyon, directly south of Area G. The tritium flux data were used to generate an estimated annual emission rate of 14 Curies/yr for all of Area G, with the majority of this activity being emitted from …
Date: March 15, 1995
Creator: Eklund, B.
Object Type: Report
System: The UNT Digital Library
Equity implications of utility energy conservation programs (open access)

Equity implications of utility energy conservation programs

This paper uses the Residential Energy Consumption Survey undertaken by the Energy Information Administration in 1990 to estimate the statistical association between household income and participation in electric utility energy conservation programs and the association between participation and the electricity consumption. The results indicate that utility rebates, energy audits, load management programs and other conservation measures tend to be undertaken at greater frequency by high income households than by low income households. Participants in conservation programs tend to occupy relatively new and energy efficient residences and undertake conservation measures other than utility programs, which suggests that utility sponsored programs are substitutes for other conservation investments. Electricity consumption during 1990 is not significantly less for households participating in utility programs than for nonparticipants, which also implies that utility conservation programs are displacing other conservation investments. Apparently, utility programs are not avoiding costs of new construction and instead are transferring wealth, particularly to high income participating households.
Date: March 15, 1994
Creator: Sutherland, R.J.
Object Type: Report
System: The UNT Digital Library
Novel complexing agents for the efficient separation of actinides and remediation of actinide-contaminated sites (open access)

Novel complexing agents for the efficient separation of actinides and remediation of actinide-contaminated sites

Research into the coordination chemistry of transactinide elements should provide us with new fundamental knowledge about structure, geometry, and stability of these metal complexes. Our approach involves the design, synthesis, and characterization of {open_quotes}expanded porphyrin{close_quotes} macrocyclic ligands which coordinate the actinide metal cations with high thermodynamic affinity and kinetic stability. We can use the knowledge from understanding the fundamental coordination chemistry of these elements as a stepping stone to heavy metal detoxification, radioactive waste cleanup, and possibly radioactive isotope separation. The critical components of this research endeavor, along with the viability of metal complex formation, will be correlated to ring size and core geometry of the ligand and, the atomic radius, oxidation state, coordination geometry and coordination number of the transactinium metal ion. These chelating agents may have certain applications to the solution of some radioactive waste problems if they can be attached to polymer supports and used to chemically separate the radioactive components in waste.
Date: March 15, 1996
Creator: Baisden, P. & Kadkhodayan, B.
Object Type: Report
System: The UNT Digital Library
The Feasibility of Monitoring Continuous Wave Sources with Seismic Arrays (open access)

The Feasibility of Monitoring Continuous Wave Sources with Seismic Arrays

This paper identifies and explores the technical requirements and issues associated with remotely monitoring continuous wave (CW) sources with seismic arrays. Potential approaches to this monitoring problem will be suggested and partially evaluated to expose the monitoring challenges which arise when realistic local geologies and cultural noise sources are considered. The selective directionality and the adaptive noise cancellation properties of arrays are required to observe weak signals while suppressing a colored background punctuated with an unknown distribution of point and sometimes distributive sources. The array is also required to characterize the emitters and propagation environment so as to properly focus on the CW sources of interest while suppressing the remaining emitters. The proper application of arrays requires an appreciation of the complexity of propagation in a non-homogeneous earth. The heterogeneity often limits the available spatial coherence and therefore the size of the army. This adversely impacts the array gain and the array's ability to carefully resolve various emitters. Arrays must also contend with multipath induced by the source and the heterogeneous earth. If the array is to focus on an emitter and realize an enhancement in the signal to noise ratio, methods must be sought to coherently add the desired …
Date: March 15, 1999
Creator: Claassen, J.P.; Elbring, G. & Ladd, M.
Object Type: Article
System: The UNT Digital Library
Influence of Surface Material on the BCl Density in Inductively Coupled Discharges (open access)

Influence of Surface Material on the BCl Density in Inductively Coupled Discharges

The relative density of BCl radicals has been measured in a modified Applied Materials DPS metal etch chamber using laser-induced fluorescence. In plasmas containing mixtures of BCl{sub 3} with Cl{sub 2}, Ar and/or N{sub 2}, the relative BCl density was measured as a function of source and bias power, pressure, flow rate, BCl{sub 3}/Cl{sub 2} ratio and argon addition. To determine the influence of surface materials on the bulk plasma properties, the relative BCl density was measured using four different substrate types; aluminum, alumina, photoresist, and photoresist-patterned aluminum. In most cases, the relative BCl density was highest above photoresist-coated wafers and lowest above blanket aluminum wafers. The BCl density increased with increasing source power and the ratio of BCl{sub 3} to Cl{sub 2}, while the addition of N{sub 2} to a BCl{sub 3}/Cl{sub 2} plasma resulted in a decrease in BCl density. The BCl density was relatively insensitive to changes in the other plasma parameters.
Date: March 15, 1999
Creator: Blain, M.G.; Hamilton, T.W. & Hebner, G.A.
Object Type: Article
System: The UNT Digital Library
Hanford low-level vitrification melter testing -- Master list of data submittals (open access)

Hanford low-level vitrification melter testing -- Master list of data submittals

The Westinghouse Hanford Company (WHC) is conducting a two-phased effort to evaluate melter system technologies for vitrification of liquid low-level radioactive waste (LLW) streams. The evaluation effort includes demonstration testing of selected glass melter technologies and technical reports regarding the applicability of the glass melter technologies to the vitrification of Hanford LLW tank waste. The scope of this document is to identify and list vendor document submittals in technology demonstration support of the Hanford Low-Level Waste Vitrification melter testing program. The scope of this document is limited to those documents responsive to the Statement of Work, accepted and issued by the LLW Vitrification Program. The purpose of such a list is to maintain configuration control of vendor supplied data and to enable ready access to, and application of, vendor supplied data in the evaluation of melter technologies for the vitrification of Hanford low-level tank wastes.
Date: March 15, 1995
Creator: Hendrickson, D.W.
Object Type: Report
System: The UNT Digital Library
The Effect of Circuiting Arrangement on the Thermal Performance of Refrigeration Mixtures in Tube-and-Fin Condensing Heat Exchangers (open access)

The Effect of Circuiting Arrangement on the Thermal Performance of Refrigeration Mixtures in Tube-and-Fin Condensing Heat Exchangers

For the pure or azeotropic refrigerants typically used in present air conditioning and refrigeration applications, the refrigerant changes phase at a constant temperature. Thus, the refrigerant circuiting arrangement such as crossfiow, counterfiow, or cross-counterflow, has no effect on the thermal performance. For zeotropic refrigerant mixtures, however, the phase-change occurs over a temperature range, or "glide", and the refrigerant circuiting arrangement, or flow path through the heat exchanger, can affect the thermal performance of both the heat exchangers as well as the overall efficiency of the vapor compression cooling cycle. The effects of tsvo diflerent circuiting arrangements on the thermal performance of a zeotropic retligerant mixture and an almost azeotropic refrigerant mixture in a four-row cross-countertlow heat exchanger arrangement are reported here. The two condensers differ only in the manner of circuiting the refrigerant tubes, where one has refrigerant always flowing downward in the active heat transfer region ("identical order") and the other has refrigerant alternating flow direction in the active heat transfer region ("inverted order"). All other geometric parameters, such as bce are% fin louver geometry, refrigerant tube size and enhancement etc., are the same for both heat exchangers. One refrigerant mixture (R-41OA) un&rgoes a small temperature change ("low glide") …
Date: March 15, 1999
Creator: Chen, D. T. & Conklin, J. C.
Object Type: Article
System: The UNT Digital Library
Test plan for glass melter system technologies for vitrification of high-sodium content low-level radioactive liquid waste, Project No. RDD-43288 (open access)

Test plan for glass melter system technologies for vitrification of high-sodium content low-level radioactive liquid waste, Project No. RDD-43288

This document provides a test plan for the conduct of combustion fired cyclone vitrification testing by a vendor in support of the Hanford Tank Waste Remediation System, Low-Level Waste Vitrification Program. The vendor providing this test plan and conducting the work detailed within it is the Babcock & Wilcox Company Alliance Research Center in Alliance, Ohio. This vendor is one of seven selected for glass melter testing.
Date: March 15, 1995
Creator: Higley, B.A.
Object Type: Report
System: The UNT Digital Library