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Interphase phenomena and the condensation of liquid metal vapors. The condensation mechanism of nitrogen tetroxide vapor

Description: Thesis. Submitted by J. Lorrain. Theoretical analyses of interphase processes involving vapors and liquids are presented. Monoatomic and reacting vapors were considered in situations such as condensation, evaporation and heat transfer between the vapor and its liquid. These developments are believed to be the most accurate to date in describing such processes. The implications of the presence of diatomic and heavier naolecules in liquid metal vapors in their condensation heat transfer are discussed. It is shown that some assumed detailed mechanisms of condensation of these species can explain the low experimental condensation heat transfer coefficients of liquid metals. Results of an experimental investigation of the condensation mechanism and condensation heat transfer of nitrogen tetroxide vapor are presented. From measurements of temperature profiles in the vapor near the vapor-llquid interface during condensation it was concluded that both major components of the vapor (nitrogen dioxide and nitrogen tetroxide) condense at comparable rates. This mechanism is in qualitative agreement with the experimental condensation heat transfer coefficients, which were found to be 10 to 20% higher than predicted by Nusselt's theory. This is apparentiy the first determination of a detailed condensation mechanism at moderate pressures where traditional methods (e.g., vacuum evaporation techniques) can not be used. (auth)
Date: April 30, 1974
Creator: Larrain, J. & Bonilla, C.F.
Partner: UNT Libraries Government Documents Department

Experimental and theoretical studies of multicomponent vapor condensation. Final report, 15 May 1992--15 May 1994

Description: This report describes the results of experimental and theoretical studies of nucleation and condensation in multicomponent gas mixtures conducted over the past ten years. The program goals were to: (1) improve basic understanding of nucleation and droplet growth, (2) stringently test theories of nucleation at high nucleation rates and under nonisothermal conditions, (3) develop improved theories where needed, (4) enlarge the data base for systems of both fundamental and practical interest, and (5) provide reliable means for predicting the behavior of mixtures in practical devices and in the atmosphere. Condensible vapors, mixed with a carrier gas, were cooled in a supersonic Laval nozzle to obtain high nucleation rates under steady state conditions. Interferometry and laser light scattering were used to detect the `onset` of condensation and to monitor subsequent droplet growth. Theoretical calculations of the droplet size distribution along the flow axis were performed to assess competing theories of nucleation and droplet growth. This report briefly summarizes the accomplishments of the first eight years. There follows a more detailed summary of the program`s final two years, and a series of appendices describing each of the studies of the final two years in considerably more detail.
Date: August 1994
Creator: Wilemski, G.; Wyslouzil, B. E. & Beals, M.
Partner: UNT Libraries Government Documents Department

The effect of the exit condition on the performance of intube condensers

Description: Data collected from the open literature plus some new, unpublished data will be used to show that the exit condition can change the flow regimes, introduce certain types of instabilities, and alter flooding velocities with intube condensation. The major orientations will be considered: horizontal, vertical with vapor downflow, and vertical with vapor upflow (refluxing).
Date: July 1, 1995
Creator: Rabas, T.J. & Arman, B.
Partner: UNT Libraries Government Documents Department

Moisture design to improve durability of low-slope roofing systems

Description: The roofing industry has traditionally held that moisture control in low-slope roofing comprises two independent elements: (1) provide a waterproof exterior covering (or membrane) to protect the low-slope roof from external sources of moisture and (2) perform a condensation calculation to determine if a vapor retarder is required to protect a roof system from internal moisture sources. The first criterion is assumed to be satisfied if a membrane system is specified; in reality, all membrane systems eventually fail, and existing moisture control strategies offer no mechanism for analyzing the inevitable failure. The means of assessing the second criterion, the need for a vapor retarder, has evolved in recent years. The criteria have become more liberal with time because it has been observed that roofing systems installed in a geographic area in which the old criteria required a vapor retarder, have performed well without one.
Date: December 31, 1996
Creator: Desjarlais, A. & Byars, N.
Partner: UNT Libraries Government Documents Department

Preoperational test report, primary ventilation condenser cooling system

Description: This represents the preoperational test report for the Primary Ventilation Condenser Cooling System, Project W-030. Project W-030 provides a ventilation upgrade for the four Aging Waste Facility tanks. The system uses a closed chilled water piping loop to provide offgas effluent cooling for tanks AY101, AY102, AZ1O1, AZ102; the offgas is cooled from a nominal 100 F to 40 F. Resulting condensation removes tritiated vapor from the exhaust stack stream. The piping system includes a package outdoor air-cooled water chiller with parallel redundant circulating pumps; the condenser coil is located inside a shielded ventilation equipment cell. The tests verify correct system operation and correct indications displayed by the central Monitor and Control System.
Date: October 29, 1997
Creator: Clifton, F.T.
Partner: UNT Libraries Government Documents Department

Final report for NIF chamber dynamics studies, final rept (May 1997), Subcontract No. B291847

Description: The National Ignition Facility (NIF), a 1.8 MJ, 192 laser beam facility, will have anticipated fusion yields of up to 20 MJ from D-T pellets encased in a gold hohlraum target. The energy emitted from the target in the form of x rays, neutrons, target debris kinetic energy, and target shrapnel will be contained in a 5 m. radius spherical target chamber. Various diagnostics will be stationed around the target at varying distances from the target. During each shot, the target will emit x rays that will vaporize nearby target facing surfaces including those of the diagnostics, the target positioner, and other chamber structures. This ablated vapor will be transported throughout the chamber, and will eventually condense and deposit on surfaces in the chamber, including the final optics debris shields. The research at the University of California at Berkeley relates primarily to the NIF chamber dynamics. The key design issues are the ablation of the chamber structures, transport of the vapor through the chamber and the condensation or deposition processes of those vaporized materials. An understanding of these processes is essential in developing a concept for protecting the final optics debris shields from an excessive coating (> 10 {Angstrom}) of target debris and ablated material, thereby prolonging their lifetime between change- outs. At Berkeley, we have studied the physical issues of the ablation process and the effects of varying materials, the condensation process of the vaporized material, and design schemes that can lower the threat posed to the debris shields by these processes. In addition to the work described briefly above, we performed extensive analysis of the target-chamber thermal response to in- chamber CO{sub 2} Cleaning and of work performed to model the behavior of silica vapor. The work completed this year has been published in several papers and a ...
Date: July 1, 1997
Creator: Peterson, P.F.; Jin, H. & Scott, J.M.
Partner: UNT Libraries Government Documents Department

Condensation analysis for plate-frame heat exchangers

Description: A theoretical analysis is presented to predict single component and binary-mixture condensation in plate-frame heat exchangers. A thermodynamic property model based on the Peng-Robinson equation of state was developed for the binary-mixture equilibrium and formulated into a performance prediction program. A set of equations was formulated and a calculation algorithm was developed to predict the local rate of heat and mass transfer for binary mixtures. Friction-factor and heat-transfer-coefficient correlations were developed using experimental data obtained with ammonia condensation. The role of the mass-transfer resistance associated with the condensation process were analyzed for a propane/butane mixture using two limiting cases: (1) no liquid-phase mass-transfer resistance, and (2) infinite liquid-phase mass-transfer resistance. The results show that the vapor-phase mass-transfer resistance is the controlling mechanism for binary-mixture condensation.
Date: July 1, 1995
Creator: Arman, B. & Rabas, T.J.
Partner: UNT Libraries Government Documents Department

TEST PLAN FOR MONITORING COOLING COILS IN A LABORATORY SETTING

Description: The objective of this research project is to understand and quantify the moisture removal performance of cooling coils at part-load conditions. The project will include a comprehensive literature review, detailed measurement of cooling coil performance in a laboratory facility, monitoring cooling systems at several field test sites, and development/validation of engineering models that can be used in energy calculations and building simulations. This document contains the detailed test plan for monitoring cooling coil performance in a laboratory setting. Detailed measurements will be taken on up to 10 direct expansion (DX) and chilled water cooling coils in various configurations to understand the impact of coil geometry and operating conditions on transient moisture condensation and evaporation.
Date: April 1, 2002
Creator: Don B. Shirey, III
Partner: UNT Libraries Government Documents Department

Cold Vacuum Drying (CVD) Facility Vacuum Purge System Chilled Water System Design Description (SYS 47-4)

Description: This system design description (SDD) addresses the Vacuum Purge System Chilled Water (VPSCHW) system. The discussion that follows is limited to the VPSCHW system and its interfaces with associated systems. The reader's attention is directed to Drawings H-1-82162, Cold Vacuum Drying Facility Process Equipment Skid P&ID Vacuum System, and H-1-82224, Cold Vacuum Drying Facility Mechanical Utilities Process Chilled Water P&ID. Figure 1-1 shows the location and equipment arrangement for the VPSCHW system. The VPSCHW system provides chilled water to the Vacuum Purge System (VPS). The chilled water provides the ability to condense water from the multi-canister overpack (MCO) outlet gases during the MCO vacuum and purge cycles. By condensing water from the MCO purge gas, the VPS can assist in drying the contents of the MCO.
Date: June 13, 2000
Creator: IRWIN, J.J.
Partner: UNT Libraries Government Documents Department

Condensation of Metal Vapors: Mercury and the Kinetic Theory of Condensation

Description: Report issued by the Argonne National Laboratory discussing condensation theories of metal vapors. As stated in the introduction, "the objectives of this research then are critical analysis of condensation theories and data for metal vapors and experimental evaluation of the resistance to condensation for a representative metal such as mercury" (p. 18). This report includes tables, illustrations, and photographs.
Date: October 1964
Creator: Wilhelm, Donald J.
Partner: UNT Libraries Government Documents Department

Condensation in a two-phase pool

Description: We consider the case of vapor condensation in a liquid pool, when the heat transfer is controlled by heat losses through the walls. The analysis is based on drift flux theory for phase separation in the pool, and determines the two-phase mixture height for the pool. To our knowledge this is the first analytical treatment of this classic problem that gives an explicit result, previous work having established the result for the evaporative case. From conservation of mass and energy in a one-dimensional steady flow, together with a void relation between the liquid and vapor fluxes, we determine the increase in the mixture level from the base level of the pool. It can be seen that the thermal and hydrodynamic influences are separable. Thus, the thermal influence of the wall heat transfer appears through its effect on the condensing length L*, so that at high condensation rates the pool is all liquid, and at low rates overflows (the level swell or foaming effect). Similarly, the phase separation effect hydrodynamically determines the height via the relative velocity of the mixture to the entering flux. We examine some practical applications of this result to level swell in condensing flows, and also examine some limits in ideal cases.
Date: December 31, 1991
Creator: Duffey, R. B. & Hughes, E. D.
Partner: UNT Libraries Government Documents Department

On the diurnal characteristics of cloud structure in the marine stratocumulus transition regime

Description: It is known that stratus-topped marine boundary layers in the mid- latitudes are subject to significant diurnal changes in structure caused by solar heating. One characteristic of the transition cloud regime that has been thoroughly explored is its diurnal variability. Although this variability has been discussed in other studies, the size of the database was restrictive. Thus, it is of importance to examine the diurnal characteristics of transition cloud structure in a larger data sample to validate the conclusions of these previous studies and to enhance our understanding of the effects of this diurnal variability on the climatology of the transition itself. The Atlantic Stratocumulus Transition Experiment (ASTEX) was designed to help understand transition clouds by making comprehensive measurements of their structure over a one-month period. Data was collected using a suite of in-situ and surface-based remote sensors deployed on the island of Santa Maria.
Date: July 1, 1996
Creator: Miller, M.A.
Partner: UNT Libraries Government Documents Department

Modeling of metallic aerosol formation in a multicomponent system at high temperatures using a discrete-sectional model. Appendix 7

Description: A multicomponent discrete-sectional model was used to simulate the fate of lead in a high temperature system. The results show the ability of the developed model to simulate metallic aerosol systems at high temperatures. The PbO reaction and nucleation rate can be determined by comparing the simulations and the experimental data. Condensation on SiO{sub 2} particle surfaces is found important for removing the PbO vapor. The value of the accommodation factor that is applied to account for nonidealities in the condensation process are determined. The differences between the nanosized particles and the bulk particles are elucidated. The use of such a model helped to understand the effects of various mechanisms in determining the metal oxide vapor concentration profile and in establishing the ultimate particle size distribution.
Date: February 1, 1997
Partner: UNT Libraries Government Documents Department

Energy-efficient windows

Description: This fact sheet describes energy efficient windows for the reduction of home heating and cooling energy consumption. It discusses controlling air leaks by caulking and weatherstripping and by replacing window frames. Reducing heat loss and condensation is discussed by describing the types of glazing materials, the number of glass and air spaces, frame and spacer materials, and the use of movable insulation (shutters, drapes, etc.). A resource list is provided for further information.
Date: October 1, 1994
Partner: UNT Libraries Government Documents Department

Deliberate ignition of hydrogen-air-steam mixtures in condensing steam environments

Description: Large scale experiments were performed to determine the effectiveness of thermal glow plug igniters to burn hydrogen in a condensing steam environment due to the presence of water sprays. The experiments were designed to determine if a detonation or accelerated flame could occur in a hydrogen-air-steam mixture which was initially nonflammable due to steam dilution but was rendered flammable by rapid steam condensation due to water sprays. Eleven Hydrogen Igniter Tests were conducted in the test vessel. The vessel was instrumented with pressure transducers, thermocouple rakes, gas grab sample bottles, hydrogen microsensors, and cameras. The vessel contained two prototypic engineered systems: (1) a deliberate hydrogen ignition system and (2) a water spray system. Experiments were conducted under conditions scaled to be nearly prototypic of those expected in Advanced Light Water Reactors (such as the Combustion Engineering (CE) System 80+), with prototypic spray drop diameter, spray mass flux, steam condensation rates, hydrogen injection flow rates, and using the actual proposed plant igniters. The lack of any significant pressure increase during the majority of the burn and condensation events signified that localized, benign hydrogen deflagration(s) occurred with no significant pressure load on the containment vessel. Igniter location did not appear to be a factor in the open geometry. Initially stratified tests with a stoichiometric mixture in the top showed that the water spray effectively mixes the initially stratified atmosphere prior to the deflagration event. All tests demonstrated that thermal glow plugs ignite hydrogen-air-steam mixtures under conditions with water sprays near the flammability limits previously determined for hydrogen-air-steam mixtures under quiescent conditions. This report describes these experiments, gives experimental results, and provides interpretation of the results. 12 refs., 127 figs., 16 tabs.
Date: May 1997
Creator: Blanchat, T. K. & Stamps, D. W.
Partner: UNT Libraries Government Documents Department

Nucleation and condensation model development

Description: This is a final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The purpose of this project was to bring to maturity a theoretical and experimental capability of the Laboratory to perform basic research in nucleation and condensation of water vapor. This report provides a general description of this capability and summarizes specific work in two areas: development and use of a combustive flow facility (CFF) to measure water monomer depletion in a supersonic nozzle and nucleation pulse experiments for investigation of transport effects on water droplet growth dynamics. The later work was performed in collaboration with Dr. Wehrner Strey in Goettingen, Germany. Preliminary water absorption data from the CFF experiment are presented. The nucleation pulse data is described along with an analysis that shows under the condition of the experiment the growth rate of water droplets is limited by monomer diffusion.
Date: September 1, 1996
Creator: Fry, H.; Lyman, J.; Breshears, D.; Zerkle, D.; Wilson, C.; Hewitt, C. et al.
Partner: UNT Libraries Government Documents Department

The DIII-D Radiative Divertor Project: Status and plans

Description: New divertor hardware is being designed and fabricated for the Radiative Divertor modification of the DIII-D tokamak. The installation of the hardware has been separated into two phases, the first phase starting in October of 1996 and the second and final phase, in 1998. The phased approach enables the continuation of the divertor characterization research in the lower divertor while providing pumping for density control in high triangularity, single- or double-null advanced tokamak discharges. When completed, the Radiative Divertor Project hardware will provide pumping at all four strike points of a double-null, high triangularity discharge and provide baffling of the neutral particles from transport back to the core plasma. By puffing neutral gas into the divertor region, a reduction in the heat flux on the target plates will be be demonstrated without a large rise in core density. This reduction in heat flux is accomplished by dispersing the power with radiation in the divertor region. Experiments and modeling have formed the basis for the new design. The capability of the DIII-D cryogenic system is being upgraded as part of this project. The increased capability of the cryogenic system will allow delivery of liquid helium and nitrogen to three new cryopumps. Physics studies on the effects of slot width and length can be accomplished easily with the design of the Radiative Divertor. The slot width can be varied by installing graphite tiles of different geometry. The change in slot length, the distance from the X-point to the target plate, requires relocating the structure vertically and can be completed in about 6-8 weeks. Radiative Divertor diagnostics are being designed to provide comprehensive measurements for diagnosing the divertor. Required diagnostic modifications will be minimal for Phase 1, but extensive for Phase 2 installation. These Phase 2 diagnostics will be required to fully diagnose ...
Date: October 1, 1996
Creator: Smith, J.P.; Baxi, C.B. & Bozek, A.S.
Partner: UNT Libraries Government Documents Department

Condensing economizers for small coal-fired boilers and furnaces

Description: Condensing economizers increase the thermal efficiency of boilers by recovering sensible and latent heat from exhaust gas. These economizers are currently being used commercially for this purpose in a wide range of applications. Performance is dependent upon application-specific factors affecting the utility of recovered heat. With the addition of a condensing economizer boiler efficiency improvements up to 10% are possible. Condensing economizers can also capture flue gas particulates. In this work, the potential use of condensing economizers for both efficiency improvement and control of particulate emissions from small, coal water slurry-fired boilers was evaluated. Analysis was done to predict heat transfer and particulate capture by mechanisms including: inertial impaction, interception, diffusion, thermophoretic forces, and condensation growth. Shell-and-tube geometries were considered with flue gas on the outside of Teflon-covered tubes. Experimental studies were done with both air- and water-cooled economizers refit to a small boiler. Two experimental arrangements were used including oil-firing with injection of flyash upstream of the economizer and direct coal water slurry firing. Firing rates ranged from 27 to 82 kW (92,000 to 280,000 Btu/hr). Inertial impaction was found to be the most important particulate capture mechanism and removal efficiencies to 95% were achieved. With the addition of water sprays directly on the first row of tubes, removal efficiencies increased to 98%. Use of these sprays adversely affects heat recovery. Primary benefits of the sprays are seen to be the addition of small impaction sites and future design improvements are suggested in which such small impactors are permanently added to the highest velocity regions of the economizer. Predicted effects of these added impactors on particulate removal and pressure drop are presented.
Date: January 1, 1994
Creator: Butcher, T.A. & Litzke, W.
Partner: UNT Libraries Government Documents Department

Condensation enhancement on a pool surface caused by a submerged liquid jet

Description: One advanced nuclear reactor design has a residual heat removal (RHR) pipe connected to the bottom of a steam generator outlet plenum. The water in the plenum can become thermally stratified during postulated loss of coolant accidents. Cold water injected through the RHR pipe has the potential effect of increasing the steam condensation on the pool surface due to the stirring action of the jet. The amount of increase depends on a number of factors, including the jet velocity and the pool height above the jet injection point. Prediction of steam condensation rates, before and after the jet breaks the pool surface, is the topic of this paper. Data and correlations exist for pre surface breakthrough and a method has been developed for post breakthrough. The models have been incorporated into the reactor safety analysis computer software known as RELAP5. Comparisons of predictions against data are presented.
Date: May 1997
Creator: Shumway, R. W.
Partner: UNT Libraries Government Documents Department

Moisture Control Handbook: New, low-rise, residential construction

Description: Moisture problems are prevalent all over North America, almost independent of climate. They are viewed as one of the single largest factors limiting the useful service life of a building. Elevated levels of moisture in buildings also can lead to serious health effects for occupants. Until recently, very little consensus on moisture control existed in the building community. The information available was typically incomplete, contradictory, usually limited to specific regions, and in many cases misleading. A need to develop a document which presented the issues relating to moisture from a building science or ``systems`` approach existed. This handbook attempts to fill that need and illustrates that energy-efficient, tight envelope design is clearly part of the solution to healthy buildings when interior relative humidity, temperature, and pressure are controlled simultaneously. The first three chapters of the handbook present the basic principles of moisture problems and solutions in buildings. Chapter 1 -- Mold, Mildew, and Condensation, examines surface moisture problems. Chapter 2 -- Moisture Movement, examines how building assemblies get wet from both the exterior and interior. Chapter 3 -- Wetting and Drying of Building Assemblies, introduces the concepts of acceptable performance, moisture balance, and the redistribution of moisture within building assemblies. Chapters 4 through 6 apply the concepts outlined in the previous chapters and present specific moisture control practices for three basic US climate zones. The advantages and disadvantages of several wall, foundation, and roof assemblies are discussed for each climate zone.
Date: October 1, 1991
Creator: Lstiburek, J. & Carmody, J.
Partner: UNT Libraries Government Documents Department

Condensation pressures in small pores: An analytical model based on density functional theory

Description: Adsorption and condensation are critical to many applications of porous materials including filtration, separation, and the storage of gases. Integral methods are used to derive an analytical expression describing fluid condensation pressures in slit pores bounded by parallel plane walls. To obtain this result, the governing equations of Density Functional Theory (DFT) are integrated across the pore width assuming that fluid densities within adsorbed layers are spatially uniform. The thickness, density, and energy of these layers are expressed as composite functions constructed from asymptotic limits applicable to small and large pores. By equating the total energy of the adsorbed layers to that of a liquid-full pore, the authors arrive at a closed-form expression for the condensation pressure in terms of the pore size, surface tension, and Lennard-Jones parameters of the adsorbent and adsorbate molecules. The resulting equation reduces to the Kelvin equation in the large-pore limit. It further reproduces the condensation pressures computed by means of the full DFT equations for all pore sizes in which phase transitions are abrupt. Finally, in the limit of extremely small pores, for which phase transitions may be smooth and continuous, this simple analytical expression provides a good approximation to the apparent condensation pressure indicated by the steepest portion of the adsorption isotherm computed via DFT.
Date: February 1, 1999
Creator: Nilson, R. H. & Griffiths, S. K.
Partner: UNT Libraries Government Documents Department

Impact of cloud microphysics on cloud-radiation interactions in the CSU general circulation model

Description: Our ability to study and quantify the impact of cloud-radiation interactions in studying global scale climate variations strongly relies upon the ability of general circulation models (GCMs) to simulate the coupling between the spatial and temporal variations of the model-generated cloudiness and atmospheric moisture budget components. In particular, the ability of GCMs to reproduce the geographical distribution of the sources and sinks of the planetary radiation balance depends upon their representation of the formation and dissipation of cloudiness in conjunction with cloud microphysics processes, and the fractional amount and optical characteristics of cloudiness in conjunction with the mass of condensate stored in the atmosphere. A cloud microphysics package which encompasses five prognostic variables for the mass of water vapor, cloud water, cloud ice, rain, and snow has been implemented in the Colorado State University General Circulation Model (CSU GCM) to simulate large-scale condensation processes. Convection interacts with the large-scale environment through the detrainment of cloud water and cloud ice at the top of cumulus towers. The cloud infrared emissivity and cloud optical depth of the model-generated cloudiness are interactive and depend upon the mass of cloud water and cloud ice suspended in the atmosphere. The global atmospheric moisture budget and planetary radiation budget of the CSU GCM obtained from a perpetual January simulation are discussed. Geographical distributions of the atmospheric moisture species are presented. Global maps of the top-of-atmosphere outgoing longwave radiation and planetary albedo are compared against Earth Radiation Budget Experiment (ERBE) satellite data.
Date: April 1, 1995
Creator: Fowler, L.D. & Randall, D.A.
Partner: UNT Libraries Government Documents Department