Science.gov

Sample records for vertical ground-coupled heat

  1. Ground-coupled heat pump demonstration

    NASA Astrophysics Data System (ADS)

    Oconnell, T.

    1983-09-01

    The results of a field evaluation of an innovative ground-coupled heat pump system which features a unique collector design and system control strategy aimed at maximizing heat pump performance by minimizing ground temperature change is discussed. The collector design includes several short closed loops, each consisting of a pair of polyethylene pipes buried 12 to 18 inches apart in a horizontal trench approximately six feet below ground. A micropressor is used to control flow and optimize system operation. Extrapolation of the results of experiments conducted on a unit length (250 ft.) of collector field during the 1981-82 and 1982-83 heating seasons indicates that a system seasonal performance factor of 2.75 to 3.0 will be achievable in practice.

  2. Ground-coupled heat pump demonstration

    SciTech Connect

    O'Connell, T.

    1983-09-01

    This report presents the results of a field evaluation of an innovative ground-coupled heat pump system which features a unique collector design and system control strategy aimed at maximizing heat pump performance by minimizing ground temperature change. The collector design includes several short closed loops, each consisting of a pair of polyethylene pipes buried 12 to 18 inches apart in a horizontal trench approximately six feet below ground. A micropressor is used to control flow and optimize system operation. Extrapolation of the results of experiments conducted on a unit length (250 ft.) of collector field during the 1981-82 and 1982-83 heating seasons indicates that a system seasonal performance factor of 2.75 to 3.0 will be achievable in practice.

  3. Cooperative heat transfer and ground coupled storage system

    DOEpatents

    Metz, Philip D.

    1982-01-01

    A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally maximally available. Thereafter, when said heat energy is seasonally minimally available and has propagated through the adjacent ground a substantial distance, the stored heat energy may be retrieved by a circumferentially arranged heat transfer means having a high rate of heat transfer.

  4. Cooperative heat transfer and ground coupled storage system

    DOEpatents

    Metz, P.D.

    A cooperative heat transfer and ground coupled storage system wherein collected solar heat energy is ground stored and permitted to radiate into the adjacent ground for storage therein over an extended period of time when such heat energy is seasonally maximally available. Thereafter, when said heat energy is seasonally minimally available and has propagated through the adjacent ground a substantial distance, the stored heat energy may be retrieved by a circumferentially arranged heat transfer means having a high rate of heat transfer.

  5. Thermal and economic assessment of ground-coupled storage for residential solar heat pump systems

    NASA Astrophysics Data System (ADS)

    Choi, M. K.; Morehouse, J. H.

    1980-11-01

    This study performed an analysis of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating were determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, D.C., Fort Worth, Tex., and Madison, Wis. The results indicate that without tax credits a combined solar/ground-coupled heat pump system for space heating and cooling is not cost competitive with conventional systems. Its thermal performance is considerably better than non-ground-coupled solar heat pumps in Forth Worth. Though the ground-coupled stand-alone heat pump provides 51% of the heating and cooling load with non-purchased energy in Forth Worth, its thermal performance in Washington and Madison is poor.

  6. Comparison of ground-coupled solar-heat-pump systems to conventional systems for residential heating, cooling and water heating

    NASA Astrophysics Data System (ADS)

    Choi, M. K.; Morehouse, J. H.; Hughes, P. J.

    1981-07-01

    An analysis is performed of ground-coupled stand-alone and series configured solar-assisted liquid-to-air heat pump systems for residences. The year-round thermal performance of these systems for space heating, space cooling, and water heating is determined by simulation and compared against non-ground-coupled solar heat pump systems as well as conventional heating and cooling systems in three geographic locations: Washington, DC; Fort Worth, Texas; and Madison, Wisconsin. The results indicate that without tax credits a combined solar/ground-coupled heat pump system for space heating and cooling is not cost competitive with conventional systems. Its thermal performance is considerably better than non-ground-coupled solar heat pumps in Fort Worth. Though the ground-coupled stand-alone heat pump provides 51 percent of the heating and cooling load with non-purchased energy in Fort Worth, its thermal performance in Washington and Madison is poor.

  7. Performance comparison of air- and ground-coupled heat pump systems. Final report

    SciTech Connect

    Parker, J.D.; Kavanaugh, S.; Ramanathan, R.

    1984-01-01

    Research initiated in 1979 to compare the performance of air-coupled and ground-coupled heat pumps is described. Three heat pump systems were installed in small, neighboring all-electric residences served by the Oklahoma Gas and Electric Company in Perkins, Oklahoma. An air-coupled heat pump and two ground-coupled heat pumps - one with solar assistance - were field tested. However, equipment and instrumentation problems precluded gathering meaningful data for the solar-assisted ground-coupled system. Generally, the unassisted ground-coupled heat pump system proved superior to the air-coupled system, both in reducing peak demand and in consuming less energy on an annual basis. The unassisted ground-coupled system reduced summer and winter peak demand, and experienced no performance degradation due to buildup of rejected waste heat in the ground well. A polyethylene U-tube ground heat exchanger was installed in both ground-coupled systems midway through the project, replacing a five-inch annular PVC pipe arrangement that had functioned poorly. The U-tube performed well throughout the remainder of research. Differing lifestyles and thermostat changes by building occupants during the monitoring period produced quite different demands and loads in the test houses, but when results were normalized through simulation, the superior performance of the unassisted ground-coupled heat pump was confirmed.

  8. Ground-Coupled Heating-Cooling Systems in Urban Areas: How Sustainable Are They?

    ERIC Educational Resources Information Center

    Younger, Paul L.

    2008-01-01

    Ground-coupled heating-cooling systems (GCHCSs) exchange heat between the built environment and the subsurface using pipework buried in trenches or boreholes. If heat pumps in GCHCSs are powered by "green electricity," they offer genuine carbon-free heating-cooling; for this reason, there has been a surge in the technology in recent years.…

  9. Ground coupled solar heat pumps: analysis of four options

    SciTech Connect

    Andrews, J.W.

    1981-01-01

    Heat pump systems which utilize both solar energy and energy withdrawn from the ground are analyzed using a simplified procedure which optimizes the solar storage temperature on a monthly basis. Four ways of introducing collected solar energy to the system are optimized and compared. These include use of actively collected thermal input to the heat pump; use of collected solar energy to heat the load directly (two different ways); and use of a passive option to reduce the effective heating load.

  10. Ground coupled heat-pump-system experimental results

    NASA Astrophysics Data System (ADS)

    Metz, P. D.

    1983-06-01

    Since October 1980, a small house in Upton, Long Island, New York has been heated and cooled by a liquid source heat pump using a shallow serpentine earth coil as a heat source/sink. After a brief introduction and system description, system performance data are presented, for the winter of 1981-82 and the summer of 1982, followed by a discussion of these results. The experimental test house is a 104 m(2) (1120 ft(2)) 3 bedroom ranch of energy saving construction with a heating load of 7.8 x 10 to the 6th power J/0C-day (4.1 x 10 to the 3rd power Btu/0F-day). The heat pump used during most of the period reported on here is a commercially available water to air unit sized to just meet the building design heating load with no auxiliary heat. The earth coil contains 155 m (507 ft) of nominal 1-1/2 in. medium density polyethylene pipe, and is approximately 25% ethylene glycol in water, is employed to permit subfreezing earth coil operation. Two independent data acquisition systems, a datalogger microcomputer system backed up by a Btu meter, monitor the space conditioning system performance.

  11. Second generation ground coupled solar assisted heat pump systems. Six month progress report

    SciTech Connect

    Rhodes, G W; Backlund, J C; Helm, J M

    1981-01-01

    Progress is reported on an investigation of the technical and commercial viability of a novel ground coupled, solar assisted heat pump system for residential space heating and cooling applications. Specific areas of study are solar collector/heat rejector performance, flat plate earth heat exchanger performance, system performance simulations, and commercialization and marketing analysis. Collector/rejector performance, determined by various thermal experiments, is discussed. The design and construction of an experimental site to study ground coupling is discussed. Theoretical analysis is also presented. The performance of the GCSAHP system and conventional alternatives, as determined by simple computer models, is presented and discussed. Finally, the commercial viability of this unique space conditioning system is examined.

  12. Design, operation and performance of a ground coupled heat pump system in a cold climate

    NASA Astrophysics Data System (ADS)

    Metz, P. D.

    An antifreeze filled serpentine earth coil was designed to just meet heating needs of a small, well insulated house with an average brine temperature never less than 7 C (20 F). The 155 m (507 ft) long, 1.2 m (4 ft) coil made from nominal size 1-1/2 in medium density polyethylene pipe was installed by a local plumbing contractor using two different chain driven trenchers. A commercially available water to air heat pump was used with minor modifications. System performance was monitored using kilowat hour meters, a Btu meter, and a datalogger microcomputer data acquisition system. The house temperature was kept between 21 and 23 C (70 and 74 F) all winter despite outdoor temperature as low as 24 C (-11 F). During a period when the outdoor temperature averaged -2 C (28 F), the system extracted approximately 10.2 x 10 to the 9th power 3 (9.7 x 10 to the 6th power Btu) from the ground with an almost constant heat pump COP (coefficient of performance) averaging about 2.3 and a system COP of 2.2. No resistance heating was used.

  13. Thermal performance of soils and backfills in horizontal ground coupled heat pump system applications. Final report

    SciTech Connect

    1998-04-01

    The goal of this research was to address the appropriateness of different soils, in an unsaturated state, for placement adjacent to the buried heat exchanger for GSHP systems. Soils for the study were selected based on an analysis of common soil parent materials that exist in the US in conjunction with the current EPRI soil thermal classification system. Six soils were chosen (Cecil (clay), Fordville (sand), Kranzburg (loam), Moody (silt), Sharpsburg (silt) and Vienna (sandy loam)) which provided at least one soil in each of the EPRI classifications. Initial laboratory studies were concentrated on determination of basic physical, water holding and thermal properties of each soil. Each soil was evaluated for ability to sustain thermal contact conductance under thermal loading, and comparison of the results allowed the soils to be ranked, best to worst. Additional laboratory studies were performed on each soil to rate the long-term thermal performance of each relative to potential for drying adjacent to the heat exchanger along with reduction in heat transfer rate due to soil drying. Tests were conducted over a range of initial water contents and densities that would be common for each soil. Results were used to verify a theoretical analysis of the thermal stability of each soil, based on texture, and to rank each soil according to thermal performance under extended thermal load. Results of the thermal conductivity tests, the thermal contact conductance tests and the thermal performance tests were utilized to propose a thermal performance index (TPI) for soils based on texture. The final soil ranking were then expressed relative to the EPRI soil thermal classification system which identified clay as best, followed by loam, sandy loam, silt, and sand.

  14. Development of a Validated Model of Ground Coupling

    SciTech Connect

    Metz, P. D.

    1980-01-01

    A research program at Brookhaven National Laboratory (BNL) studies ground coupling, the use of the earth as a heat source/sink or storage element for solar heat pump space conditioning systems. This paper outlines the analytical and experimental research to date toward the development of an experimentally validated model of ground coupling and based on experimental results from December, 1978 to September, 1979, expores sensitivity of present model predictions to variations in thermal conductivity and other factors. Ways in which the model can be further refined are discussed.

  15. Vertical eddy heat fluxes from model simulations

    NASA Technical Reports Server (NTRS)

    Stone, Peter H.; Yao, Mao-Sung

    1991-01-01

    Vertical eddy fluxes of heat are calculated from simulations with a variety of climate models, ranging from three-dimensional GCMs to a one-dimensional radiative-convective model. The models' total eddy flux in the lower troposphere is found to agree well with Hantel's analysis from observations, but in the mid and upper troposphere the models' values are systematically 30 percent to 50 percent smaller than Hantel's. The models nevertheless give very good results for the global temperature profile, and the reason for the discrepancy is unclear. The model results show that the manner in which the vertical eddy flux is carried is very sensitive to the parameterization of moist convection. When a moist adiabatic adjustment scheme with a critical value for the relative humidity of 100 percent is used, the vertical transports by large-scale eddies and small-scale convection on a global basis are equal: but when a penetrative convection scheme is used, the large-scale flux on a global basis is only about one-fifth to one-fourth the small-scale flux. Comparison of the model results with observations indicates that the results with the latter scheme are more realistic. However, even in this case, in mid and high latitudes the large and small-scale vertical eddy fluxes of heat are comparable in magnitude above the planetary boundary layer.

  16. Boiling heat transfer enhancement in subsurface horizontal and vertical tunnels

    SciTech Connect

    Pastuszko, Robert

    2008-09-15

    Complex experimental investigations of boiling heat transfer on structured surfaces covered with perforated foil were taken up. Experimental data were discussed for two kinds of enhanced surfaces formed by joined horizontal and vertical tunnels: tunnel structures (TS) and narrow tunnel structures (NTS). The experiments were carried out with water, ethanol and R-123 at atmospheric pressure. The TS and NTS surfaces were manufactured out of perforated copper foil of 0.05 mm thickness (hole diameters: 0.3, 0.4, 0.5 mm) sintered with the mini-fins, formed on the vertical side of the 5 mm high rectangular fins and horizontal inter-fin surface. The effects of hole (pore) diameters, tunnel pitch for TS and tunnel width for NTS on nucleate pool boiling were examined. Substantial enhancement of heat transfer coefficient was observed. The investigated surfaces showed boiling heat transfer coefficients similar to those of existing structures with subsurface tunnels, but at higher heat fluxes range. (author)

  17. Hydraulic characteristics of mixed convection in a heated vertical pipe

    SciTech Connect

    Jianchiu Han . Dept. of Mechanical Engineering)

    1993-03-01

    By studying the integrated governing equations for mixed convection in a vertical pipe heated with constant wall heat flux, several concepts (or misconcepts) regarding convection mode and flow regimes are examined. A new alternative definition of convection mode reflecting the force balance in mixed convection is given. A new parameter, m (M), is introduced to quantitatively characterize various regimes for mixed convection. Two specific cases for laminar and turbulent air flow with Re = 500 and 5,000 respectively are studied numerically in detail. Typical behavior of m(M) for each case and other associated hydraulic characteristics of mixed convection are illustrated and discussed.

  18. Retrieving Latent Heat Vertical Structure Using Precipitation and Cloud Profiles

    NASA Astrophysics Data System (ADS)

    Li, R.; Min, Q.; Wu, X.

    2011-12-01

    The latent heat (LH) released from tropical precipitation plays a critical role in driving regional and global atmosphere circulation. However, the vertical distribution of LH is one of most difficult parameters to be measured and has a large uncertainty in both residual diagnostic products and satellite retrievals. Most of current satellite LH products use limited observational information of precipitation and cloud profiles and highly depend on cloud resolving model (CRM) simulations. Our novel approach, distinguishing from existing schemes, is directly using observable precipitation and cloud profiles in combination with phase change partition parameterization of various kinds from the CRM simulations to produce the latent heating profiles. This hybrid latent heat algorithm separately deals with the condensation-evaporation heating (LHc_e), the deposition-sublimation heating (LHd_s) and the freezing-melting heating (LHf_m) for convective rain, stratiform rain, and shallow warm rain. Each component is based on physical processes, such as nucleation and auto conversion, by combining observable precipitation and cloud profiles. Although the proposed algorithm utilizes microphysical parameterizations from a specific CRM, the general LH vertical structure is primarily determined by the precipitation and cloud profiles observable from cloud and precipitation radars available at ground sites or from satellite platforms, and less sensitive to the specific CRM. The self consistency tests of this algorithm show good agreements with the CRM simulated LH at different spatial and temporal scales, even at simultaneous and pixel level. The applications of this algorithm are expected to provide new information for understanding the heating budget in the atmosphere and its impacts on the atmosphere circulations at various spatial and temporal scales.

  19. Heat transfer in vertically aligned phase change energy storage systems

    SciTech Connect

    El-Dessouky, H.T.; Bouhamra, W.S.; Ettouney, H.M.; Akbar, M.

    1999-05-01

    Convection effects on heat transfer are analyzed in low temperature and vertically aligned phase change energy storage systems. This is performed by detailed temperature measurements in the phase change material (PCM) in eighteen locations forming a grid of six radial and three axial positions. The system constitutes a double pipe configuration, where commercial grade paraffin wax is stored in the annular space between the two pipes and water flows inside the inner pipe. Vertical alignment of the system allowed for reverse of the flow direction of the heat transfer fluid (HTF), which is water. Therefore, the PCM is heated from the bottom for HTF flow from bottom to top and from the top as the HTF flow direction is reversed. For the former case, natural convection affects the melting process. Collected data are used to study variations in the transient temperature distribution at axial and radial positions as well as for the two-dimensional temperature field. The data are used to calculate the PCM heat transfer coefficient and to develop correlations for the melting Fourier number. Results indicate that the PCM heat transfer coefficient is higher for the case of PCM heating from bottom to top. Nusselt number correlations are developed as a function of Rayleigh, Stefan, and Fourier numbers for the HTF flow from bottom to top and as a function of Stefan and Fourier numbers for HTF flow from top to bottom. The enhancement ratio for heat transfer caused by natural convection increases and then levels off as the inlet temperature of the HTF is increased.

  20. Spray cooling heat-transfer with subcooled trichlorotrifluoroethane (Freon-113) for vertical constant heat flux surfaces

    SciTech Connect

    Kendall, C.M.; Holman, J.P.

    1996-06-06

    Experiments were done using subcooled Freon-113 sprayed vertically downward. Local and average heat transfers were investigated fro Freon-113 sprays with 40 C subcooling, droplet sizes 200-1250{mu}m, and droplet breakup velocities 5-29 m/s. Full-cone type nozzles were used to generate the spray. Test assemblies consisted of 1 to 6 7.62 cm vertical constant heat flux surfaces parallel with each other and aligned horizontally. Distance between heated surfaces was varied from 6.35 to 76.2 mm. Steady state heat fluxes as high as 13 W/cm{sup 2} were achieved. Dependence on the surface distance from axial centerline of the spray was found. For surfaces sufficiently removed from centerline, local and average heat transfers were identical and correlated by a power relation of the form seen for normal-impact sprays which involves the Weber number, a nondimensionalized temperature difference, and a mass flux parameter. For surfaces closer to centerline, the local heat transfer depended on vertical location on the surface while the average heat transfer was described by a semi-log correlation involving the same parameters. The heat transfer was independent of the distance (gap) between the heated surfaces for the gaps investigated.

  1. Momentum and heat transport scalings in laminar vertical convection.

    PubMed

    Shishkina, Olga

    2016-05-01

    We derive the dependence of the Reynolds number Re and the Nusselt number Nu on the Rayleigh number Ra and the Prandtl number Pr in laminar vertical convection (VC), where a fluid is confined between two differently heated isothermal vertical walls. The boundary layer equations in laminar VC yield two limiting scaling regimes: Nu∼Pr^{1/4}Ra^{1/4}, Re∼Pr^{-1/2}Ra^{1/2} for Pr≪1 and Nu∼Pr^{0}Ra^{1/4}, Re∼Pr^{-1}Ra^{1/2} for Pr≫1. These theoretical results are in excellent agreement with direct numerical simulations for Ra from 10^{5} to 10^{10} and Pr from 10^{-2} to 30. The transition between the regimes takes place for Pr around 10^{-1}. PMID:27300823

  2. Momentum and heat transport scalings in laminar vertical convection

    NASA Astrophysics Data System (ADS)

    Shishkina, Olga

    2016-05-01

    We derive the dependence of the Reynolds number Re and the Nusselt number Nu on the Rayleigh number Ra and the Prandtl number Pr in laminar vertical convection (VC), where a fluid is confined between two differently heated isothermal vertical walls. The boundary layer equations in laminar VC yield two limiting scaling regimes: Nu˜Pr1/4Ra1/4 , Re˜Pr-1/2Ra1/2 for Pr≪1 and Nu˜Pr0Ra1/4 , Re˜Pr-1Ra1/2 for Pr≫1 . These theoretical results are in excellent agreement with direct numerical simulations for Ra from 105 to 1010 and Pr from 10-2 to 30. The transition between the regimes takes place for Pr around 10-1.

  3. Flow regimes and heat transfer in vertical narrow annuli

    SciTech Connect

    Ulke, A.; Goldberg, I.

    1993-11-01

    In shell side boiling heat exchangers narrow crevices that are formed between the tubes and the tube support structure provide areas for local thermal-hydraulic conditions which differ significantly from bulk fluid conditions. Understanding of the processes of boiling and dryout in flow restricted crevices can help in designing of tube support geometries to minimize the likelihood of tube support plate and tube corrosion observed in commercial power plant steam generators. This paper describes a one dimensional thermal-hydraulic model of a vertical crevice between a tube and a support plate with cylindrical holes. The annulus formed by the support plate hole and an eccentrically located tube has been represented by vertical strips. The formation, growth and collapse of a steam bubble in each strip has been determined. Based on the bubble history, and flow regimes characterized by ``isolated`` bubbles, ``coalesced`` bubbles and liquid deficient regions have been defined.

  4. Mixed turbulent convective heat transfer in vertical ducts

    NASA Astrophysics Data System (ADS)

    Swanson, Larry William

    Time averaged and dynamic heat transfer phenomena associated with opposing mixed turbulent convection in vertical ducts were studied both experimentally and theoretically. Surface renewal theory and experimental data were used to obtain a time averaged heat transfer correlation containing the proper parameter functionality. The heat transfer dynamics of large scale flow phenomena observed were also investigated experimentally. Time series and Poincare maps were initially generated and compared with flow observations. The results indicated that although many different flow structures and flow sequences existed at the various parameter settings, the most predominant flow structure was a large single cell. All of the power spectral densities computed from the time series display broad band noise with the average power decreasing with increasing frequency. No bifurcation sequences characterizing a large scale transition mechanism could be established. Finally, the Grassberger-Proccacia dimension algorithm was implemented for data obtained at a wall heat flux of 0.4533 (Btu/sq ft/s) and a volumetric flow rate of 0.03384 (cu ft/s).

  5. The effect of asymmetric heating on flow stability and heat transfer for flow in a vertical tube

    SciTech Connect

    Tappan, C.H.

    1987-11-01

    This study presents experimental results of combined free and forced convection heat transfer in a vertical tube with a circumferentially nonuniform constant wall heat flux. The effect of an asymmetric wall heat flux on flow stability and on the rate of heat transfer for water flowing downward in a vertical tube was investigated. Experimental results were used to develop two stability maps which identify various flow regimes, corresponding to different thermal and hydraulic conditions. Heat transfer coefficients were also determined. Experimental results in the present investigation were compared to those with uniform heating in horizontal and vertical tube flow situations discussed in the literature. 23 refs., 12 figs., 1 tab.

  6. Effect of the heating surface enhancement on the heat transfer coefficient for a vertical minichannel

    NASA Astrophysics Data System (ADS)

    Piasecka, Magdalena; Strąk, Kinga

    2016-03-01

    The aim of the paper is to estimate effect of the heating surface enhancement on FC-72 flow boiling heat transfer for a vertical minichannel 1.7 mm deep, 24 mm wide and 360 mm long. Two types of enhanced heating surfaces were used: one with minicavities distributed unevenly, and the other with capillary metal fibrous structure. It was to measure temperature field on the plain side of the heating surface by means of the infrared thermography and to observe the two-phase flow patterns on the enhanced foil side. The paper analyses mainly the impact of the microstructured heating surface on the heat transfer coefficient. The results are presented as heat transfer coefficient dependences on the distance along the minichannel length. The data obtained using two types of enhanced heating surfaces in experiments was compared with the data when smooth foil as the heating surface was used. The highest local values of heat transfer coefficient were obtained using enhanced foil with minicavities - in comparison to other cases. Local values of heat transfer coefficient received for capillary fibrous structure were the lowest, even compared with data obtained for smooth foil. Probably this porous structure caused local flow disturbances.

  7. Heat exchanger sizing for vertical closed-loop ground-source heat pumps

    SciTech Connect

    Cane, R.L.D.; Clemes, S.B.; Morrison, A.; Hughes, P.J.

    1995-12-31

    A building energy simulation program has been used in conjunction with a ground heat exchanger sizing algorithm to develop general guidelines on how to size vertical ground heat exchangers for closed-loop ground-source heat pump systems in large buildings. The analysis considered three commercial building types of varying size with different internal loads and heat pump efficiencies. Each building variation was simulated in seven cities, three in the US and four in Canada. The ground heat exchanger sizing algorithm has been previously validated against actual system data. The analysis results showed a strong correlation between heat exchanger length required and annual energy rejected to the ground, if the building was cooling-dominated, or annual energy extracted from the ground, if the building was heating-dominated. The resulting sizing guidelines recommend hour-by-hour energy analysis to determine the energy extracted from and rejected to the building water loop. Using this information the designer will have available easy-to-use, accurate sizing guidelines that should result in more economical installations than those based on previous ``rule of thumb`` guidelines.

  8. Observing the Vertical Dimensions of Singapore's Urban Heat Island

    NASA Astrophysics Data System (ADS)

    Chow, W. T. L.; Ho, D. X. Q.

    2015-12-01

    In numerous cities, measurements of urban warmth in most urban heat island (UHI) studies are generally constrained towards surface or near-surface (<2 m above ground) levels across horizontal variations in land use and land cover. However, there has been hitherto limited attention towards the measurement of vertical temperature profiles extending from the urban surface through to the urban boundary layer. Knowledge of these profiles, through how they vary over different local urban morphologies, and develop with respect to synoptic meteorological conditions, are important towards several aspects of UHI research; these include validating modelling urban canopy lapse rate profiles or estimating the growth of urban plumes. In this study, we utilised temperature sensors attached onto remote controlled aerial quadcopter platforms to measure urban temperature and humidity profiles in Singapore, which is a rapidly urbanizing major tropical metropolis. These profiles were measured from the surface to ~100 m above ground level, a height which includes all of the urban canopy and parts of the urban boundary layer. Initial results indicate significant variations in stability measured over different land uses (e.g. urban park, high-rise residential, commercial); these profiles are also temporally dynamic, depending on the time of day and larger-scale weather conditions.

  9. Effect of horizontal heat and fluid flow on the vertical temperature distribution in a semiconfining layer

    USGS Publications Warehouse

    Lu, N.; Ge, S.

    1996-01-01

    By including the constant flow of heat and fluid in the horizontal direction, we develop an analytical solution for the vertical temperature distribution within the semiconfining layer of a typical aquifer system. The solution is an extension of the previous one-dimensional theory by Bredehoeft and Papadopulos [1965]. It provides a quantitative tool for analyzing the uncertainty of the horizontal heat and fluid flow. The analytical results demonstrate that horizontal flow of heat and fluid, if at values much smaller than those of the vertical, has a negligible effect on the vertical temperature distribution but becomes significant when it is comparable to the vertical.

  10. Pulse-Heated Vertical Electron Cyclotron Emission Diagnostic

    NASA Astrophysics Data System (ADS)

    Voss, Keith Edward

    1995-01-01

    Determination of plasma parameters in tokamak experiments is of primary importance for learning to control and optimize fusion plasmas. Electron cyclotron emission (ECE) diagnostics play an important role in these experiments and are planned for future test reactors, since they require only simple collecting optics in the harsh reactor environment. A novel diagnostic system, which extracts information about plasma parameters by examining the ECE resulting from a perturbation of the plasma, was examined and applied on the PBX-M tokamak. This diagnostic uses a brief pulse of power from the lower hybrid current drive system to create a population of superthermal electrons. These electrons evolve according to the Fokker-Planck equation, which involves dependences on the magnetic field pitch, ion charge state, background density, and electric field. Coincident with the evolution of the electrons is the evolution of their ECE radiation. The diagnostic exploits the fact that the temporal changes in the radiation are dependent upon those parameters which affect the electrons. The analysis method, which compares measured experimental signal with simulated radiation (as functions of frequency and time) and determines most probable plasma parameter values, was computationally tested for effectiveness and robustness. The method was extended to include determination of parameters of the lower hybrid current drive power deposition. A measurement system, based on a grating polychromator, was assembled, tested, and calibrated, and pulse-heated vertical ECE data were collected from the PBX-M tokamak. A proof-of-principle test of the diagnostic yielded positive results, resulting in information about the lower hybrid current drive deposition location.

  11. A simple model for the interaction between vertical eddy heat fluxes and static stability

    NASA Technical Reports Server (NTRS)

    Gutowski, W. J., Jr.

    1985-01-01

    A numerical model for studying the interaction of vertical eddy heat fluxes and vertical temperature structure in midlatitude regions is described. The temperature profile for the model was derived from calculations of the equilibrium among heating rates in simplified representations of large-scale vertical eddy heat flux, moist convection and radiation. An eddy flux profile is calculated based on the quasi-geostrophic, liner baroclinic instability of a single wave. Model equilibrium states for summer and winter conditions are compared with observations, and the results are discussed in detail.

  12. Flow in a rectangular closed-loop thermosyphon with vertical heat transfer passages

    NASA Astrophysics Data System (ADS)

    Durig, Brian R.; Shadday, Martin A., Jr.

    1986-12-01

    Closed-loop thermosyphons are pipe networks in which the flow is due to simultaneous heating and cooling of different sections of the pipe network. Thermosyphons are commonly modeled one-dimensionally, where wall shear is accounted for by a friction factor. When the heat transfer passages of a thermosyphon are oriented vertically, buoyancy drastically alters the flow, and forced convection friction factor and Nusselt number correlations are no longer applicable. A closed-loop rectangular thermosyphon with vertical heat transfer passages was investigated both theoretically and experimentally. Friction factor and Nusselt number correlations for the combined forced/free flow in the vertical legs of the loop were determined numerically.

  13. Method and apparatus for determining vertical heat flux of geothermal field

    DOEpatents

    Poppendiek, Heinz F.

    1982-01-01

    A method and apparatus for determining vertical heat flux of a geothermal field, and mapping the entire field, is based upon an elongated heat-flux transducer (10) comprised of a length of tubing (12) of relatively low thermal conductivity with a thermopile (20) inside for measuring the thermal gradient between the ends of the transducer after it has been positioned in a borehole for a period sufficient for the tube to reach thermal equilibrium. The transducer is thermally coupled to the surrounding earth by a fluid annulus, preferably water or mud. A second transducer comprised of a length of tubing of relatively high thermal conductivity is used for a second thermal gradient measurement. The ratio of the first measurement to the second is then used to determine the earth's thermal conductivity, k.sub..infin., from a precalculated graph, and using the value of thermal conductivity thus determined, then determining the vertical earth temperature gradient, b, from predetermined steady state heat balance equations which relate the undisturbed vertical earth temperature distributions at some distance from the borehole and earth thermal conductivity to the temperature gradients in the transducers and their thermal conductivity. The product of the earth's thermal conductivity, k.sub..infin., and the earth's undisturbed vertical temperature gradient, b, then determines the earth's vertical heat flux. The process can be repeated many times for boreholes of a geothermal field to map vertical heat flux.

  14. Vertical heat flux in the ocean: Estimates from observations and from a coupled general circulation model

    NASA Astrophysics Data System (ADS)

    Cummins, Patrick F.; Masson, Diane; Saenko, Oleg A.

    2016-06-01

    The net heat uptake by the ocean in a changing climate involves small imbalances between the advective and diffusive processes that transport heat vertically. Generally, it is necessary to rely on global climate models to study these processes in detail. In the present study, it is shown that a key component of the vertical heat flux, namely that associated with the large-scale mean vertical circulation, can be diagnosed over extra-tropical regions from global observational data sets. This component is estimated based on the vertical velocity obtained from the geostrophic vorticity balance, combined with estimates of absolute geostrophic flow. Results are compared with the output of a non-eddy resolving, coupled atmosphere-ocean general circulation model. Reasonable agreement is found in the latitudinal distribution of the vertical heat flux, as well as in the area-integrated flux below about 250 m depth. The correspondence with the coupled model deteriorates sharply at depths shallower than 250 m due to the omission of equatorial regions from the calculation. The vertical heat flux due to the mean circulation is found to be dominated globally by the downward contribution from the Southern Hemisphere, in particular the Southern Ocean. This is driven by the Ekman vertical velocity which induces an upward transport of seawater that is cold relative to the horizontal average at a given depth. The results indicate that the dominant characteristics of the vertical transport of heat due to the mean circulation can be inferred from simple linear vorticity dynamics over much of the ocean.

  15. Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part A

    NASA Astrophysics Data System (ADS)

    Badruddin, Irfan Anjum; Quadir, G. A.

    2016-06-01

    Heat transfer in a porous medium embedded with vertical flat plate is investigated by using thermal non-equilibrium model. Darcy model is employed to simulate the flow inside porous medium. It is assumed that the heat transfer takes place by natural convection and radiation. The vertical plate is maintained at isothermal temperature. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method. Results are presented in terms of isotherms and streamlines for various parameters such as heat transfer coefficient parameter, thermal conductivity ratio, and radiation parameter

  16. Heat flow experiment. [direct measurement of vertical flow of heat through lunar soil in Apollo 17 lunar landing site area

    NASA Technical Reports Server (NTRS)

    Langseth, M. G., Jr.; Keihm, S. J.; Chute, J. L., Jr.

    1973-01-01

    The heat flow experiment conducted during the Apollo 17 flight in the Taurus-Littrow area of the moon is discussed. The concept of the experiment is based on the direct measurement of the vertical flow of heat through the regolith. The measurement is made far enough below the surface so that the time-varying heat flow resulting from the very large diurnal variations of the surface temperature is small as compared with the flow from the interior. The equipment used for the experiment is described and illustrated. Graphs are developed to present the results of heat flow and surface temperature measurements.

  17. Computer cooling using a two phase minichannel thermosyphon loop heated from horizontal and vertical sides and cooled from vertical side

    NASA Astrophysics Data System (ADS)

    Bieliński, Henryk; Mikielewicz, Jarosław

    2010-10-01

    In the present paper it is proposed to consider the computer cooling capacity using the thermosyphon loop. A closed thermosyphon loop consists of combined two heaters and a cooler connected to each other by tubes. The first heater may be a CPU processor located on the motherboard of the personal computer. The second heater may be a chip of a graphic card placed perpendicular to the motherboard of personal computer. The cooler can be placed above the heaters on the computer chassis. The thermosyphon cooling system on the use of computer can be modeled using the rectangular thermosyphon loop with minichannels heated at the bottom horizontal side and the bottom vertical side and cooled at the upper vertical side. The riser and a downcomer connect these parts. A one-dimensional model of two-phase flow and heat transfer in a closed thermosyphon loop is based on mass, momentum, and energy balances in the evaporators, rising tube, condenser and the falling tube. The separate two-phase flow model is used in calculations. A numerical investigation for the analysis of the mass flux rate and heat transfer coefficient in the steady state has been accomplished.

  18. MHD natural convection flow along a vertical wavy surface with heat generation and pressure work

    NASA Astrophysics Data System (ADS)

    Alim, M. A.; Kabir, K. H.; Andallah, L. S.

    2016-07-01

    In this paper, the influence of pressure work on MHD natural convection flow of viscous incompressible fluid along a uniformly heated vertical wavy surface with heat generation has been investigated. The governing boundary layer equations are first transformed into a non-dimensional form using suitable set of dimensionless variables. The resulting nonlinear system of partial differential equations are mapped into the domain of a vertical flat plate and then solved numerically employing the implicit finite difference method, known as Keller-box scheme. The numerical results for the velocity profiles, temperature profiles, skin friction coefficient, the rate of heat transfers, the streamlines and the isotherms are shown graphically and skin friction coefficient and rate of heat transfer have been shown in tabular form for different values of the selective set of parameters consisting of pressure work parameter Ge, the magnetic parameter M, Prandtl number Pr, heat generation parameter Q and the amplitude of the wavy surface.

  19. Natural convection heat transfer in vertical triangular subchannel in Zirconia-water nanofluid

    NASA Astrophysics Data System (ADS)

    Tandian, N. P.; Alkharboushi, A. A. K.; Kamajaya, K.

    2015-09-01

    Natural convection heat transfer in vertical triangular sub-channel has important role in cooling mechanism of the APWR and the PHWR nuclear reactors. Unfortunately, natural convection correlation equations for such geometry are scarcely available. Recent studies showed that ZrO2-water nanofluid has a good prospect to be used in the nuclear reactor technology due to its low neutron absorption cross section. Although several papers have reported transport properties of ZrO2-water nanofluids, practically there is no correlation equation for predicting natural convection heat transfer in a vertical triangular sub-channel in ZrO2-water nanofluid. Therefore, a study for finding such heat transfer correlation equation has been done by utilizing Computational Fluid Dynamics software and reported in this paper. In the study, natural convection heat transfer in a vertical triangular sub-channel has been simulated at several values of heat transfer flux within 9.1 to 30.9 kW/m2 range and ZrO2 concentrations of 0 (pure water), 0.27, and 3 volume-% of ZrO2. The study shows that the ZrO2 concentration has no significant influence to the natural convection heat transfer at those concentration levels. The obtained theoretical heat transfer correlation equations were verified through experiment, and they showed very similar results. The correlation equations are reported in this paper.

  20. Experimental study of natural convective heat transfer in a vertical hexagonal sub channel

    NASA Astrophysics Data System (ADS)

    Tandian, Nathanael P.; Umar, Efrizon; Hardianto, Toto; Febriyanto, Catur

    2012-06-01

    The development of new practices in nuclear reactor safety aspects and optimization of recent nuclear reactors, including the APWR and the PHWR reactors, needs a knowledge on natural convective heat transfer within sub-channels formed among several nuclear fuel rods or heat exchanger tubes. Unfortunately, the currently available empirical correlation equations for such heat transfer modes are limited and researches on convective heat transfer within a bundle of vertical cylinders (especially within the natural convection modes) are scarcely done. Although boundary layers around the heat exchanger cylinders or fuel rods may be dominated by their entry regions, most of available convection correlation equations are for fully developed boundary layers. Recently, an experimental study on natural convective heat transfer in a subchannel formed by several heated parallel cylinders that arranged in a hexagonal configuration has been being done. The study seeks for a new convection correlation for the natural convective heat transfer in the sub-channel formed among the hexagonal vertical cylinders. A new convective heat transfer correlation equation has been obtained from the study and compared to several similar equations in literatures.

  1. Heat-transfer characteristics of climbing film evaporation in a vertical tube

    SciTech Connect

    Yang, Luopeng; Chen, Xue; Shen, Shengqiang

    2010-09-15

    Heat-transfer characteristics of climbing film evaporation were experimentally investigated on a vertical climbing film evaporator heated by tube-outside hot water. The experimental setup was designed for determining the effect of the height of feed water inside a vertical tube and the range of temperature difference on local heat transfer coefficient inside a vertical tube (h{sub i}). In this setup, the height of feed water was successfully controlled and the polypropylene shell effectively impedes the heat loss to the ground. The results indicated that a reduction in the height of feed water contributed to a significant increase in h{sub i} if no dry patches around the wall of the heated tube appeared inside the tube. The height ratio of feed water R{sub h} = 0.3 was proposed as the optimal one as dry patches destroyed the continuous climbing film when R{sub h} is under 0.3. It was found that the minimum temperature difference driving climbing film evaporation is suggested as 5 C due to a sharp reduction in h{sub i} for temperature difference below 5 C. The experiment also showed that h{sub i} increased with an increase in temperature difference, which proved the superiority of climbing film evaporation in utilizing low-grade surplus heating source due to its wide range of driving temperature difference. The experimental results were compared with the previous literature and demonstrated a satisfactory agreement. (author)

  2. Heat transfer analysis in a two-side heated smooth square vertical channel with adverse and favorable mixed convection

    SciTech Connect

    Dutta, S.; Zhang, X.; Khan, J.A.; Bell, D.

    1997-07-01

    Experimental heat transfer measurements and analysis for mixed convection in a vertical square channel are presented. The flow direction is changed with respect to the earth's gravity field by selectively opening and closing the flow control valves. Desired flow directions are selected such that buoyancy assists or opposes the bulk flow direction pressure gradient. The heating condition is asymmetric. Most previous experiments used symmetrically heated circular tubes. Present configuration shows significant increase in the Nusselt number in both assisted and opposed flow conditions. In general, opposed flow shows higher heat transfer coefficients. Unlike symmetric heating conditions, Nusselt number ratio is observed to be increasing with increasing Gr/Re or Gr/Re{sup 2} ratios for both assisted and opposed flow conditions.

  3. The Reynolds analogy for the mixed convection over a vertical surface with prescribed heat flux

    NASA Astrophysics Data System (ADS)

    Magyari, E.; Pop, I.

    2009-03-01

    The steady mixed convection boundary layer flow over a vertical surface with prescribed heat flux is revisited in this Note. The subset of solutions which can be obtained with the aid of the Reynolds analogy is discussed in a close relationship with the dual solutions reported by Merkin and Mahmood [1] for impermeable, and more recently by Ishak et al. [2], for permeable surfaces.

  4. Heat transfer in vertical Bridgman growth of oxides - Effects of conduction, convection, and internal radiation

    NASA Technical Reports Server (NTRS)

    Brandon, S.; Derby, J. J.

    1992-01-01

    In the present investigation of crystalline phase internal radiation and heat conduction during the vertical Bridgman growth of a YAG-like oxide crystal, where transport through the melt is dominated by convection and conduction, heat is also noted to be conducted through ampoule walls via natural convection and enclosure radiation. The results of a quasi-steady-state axisymmetric Galerkin FEM indicate that heat transfer through the system is powerfully affected by the optical absorption coefficient of the crystal. The coupling of internal radiation through the crystal with conduction through the ampoule walls promotes melt/crystal interface shapes that are highly reflected near the ampoule wall.

  5. Empirical models of the eddy heat flux and vertical shear on short time scales

    NASA Technical Reports Server (NTRS)

    Ghan, S. J.

    1984-01-01

    An intimate relation exists between the vertical shear and the horizontal eddy heat flux within the atmosphere. In the present investigation empirical means are employed to provide clues concerning the relationship between the shear and eddy heat flux. In particular, linear regression models are applied to individual and joint time series of the shear and eddy heat flux. These discrete models are used as a basis to infer continuous models. A description is provided of the observed relationship between the flux and the shear, taking into account means, standard deviations, and lag correction functions.

  6. Simultaneous heat and mass transfer inside a vertical channel in evaporating a heated falling glycols liquid film

    NASA Astrophysics Data System (ADS)

    Nait Alla, Abderrahman; Feddaoui, M'barek; Meftah, Hicham

    2015-12-01

    The interactive effects of heat and mass transfer in the evaporation of ethylene and propylene glycol flowing as falling films on vertical channel was investigated. The liquid film falls along a left plate which is externally subjected to a uniform heat flux while the right plate is the dry wall and is kept thermally insulated. The model solves the coupled governing equations in both phases together with the boundary and interfacial conditions. The systems of equations obtained by using an implicit finite difference method are solved by Tridiagonal Matrix Algorithm. The influence of the inlet liquid flow, Reynolds number in the gas flow and the wall heat flux on the intensity of heat and mass transfers are examined. A comparison between the results obtained for studied glycols and water in the same conditions is made. The results indicate that water evaporates in more intense way in comparison to glycols and the increase of gas flow rate tends to improve slightly the evaporation.

  7. The impact of bed temperature on heat transfer characteristic between fluidized bed and vertical rifled tubes

    NASA Astrophysics Data System (ADS)

    Blaszczuk, Artur; Nowak, Wojciech

    2016-10-01

    In the present work, the heat transfer study focuses on assessment of the impact of bed temperature on the local heat transfer characteristic between a fluidized bed and vertical rifled tubes (38mm-O.D.) in a commercial circulating fluidized bed (CFB) boiler. Heat transfer behavior in a 1296t/h supercritical CFB furnace has been analyzed for Geldart B particle with Sauter mean diameter of 0.219 and 0.246mm. The heat transfer experiments were conducted for the active heat transfer surface in the form of membrane tube with a longitudinal fin at the tube crest under the normal operating conditions of CFB boiler. A heat transfer analysis of CFB boiler with detailed consideration of the bed-to-wall heat transfer coefficient and the contribution of heat transfer mechanisms inside furnace chamber were investigated using mechanistic heat transfer model based on cluster renewal approach. The predicted values of heat transfer coefficient are compared with empirical correlation for CFB units in large-scale.

  8. Experimental study on flow boiling heat transfer of LNG in a vertical smooth tube

    NASA Astrophysics Data System (ADS)

    Chen, Dongsheng; Shi, Yumei

    2013-10-01

    An experimental apparatus is set up in this work to study the upward flow boiling heat transfer characteristics of LNG (liquefied natural gas) in vertical smooth tubes with inner diameters of 8 mm and 14 mm. The experiments were performed at various inlet pressures from 0.3 to 0.7 MPa. The results were obtained over the mass flux range from 16 to 200 kg m-2 s-1 and heat fluxes ranging from 8.0 to 32 kW m-2. The influences of quality, heat flux and mass flux, tube diameter on the heat transfer characteristic are examined and discussed. The comparisons of the experimental heat transfer coefficients with the predicted values from the existing correlations are analyzed. The correlation by Zou et al. [16] shows the best accuracy with the RMS deviation of 31.7% in comparison with the experimental data.

  9. Fundamental Study of Local Heat Transfer in Forced Convective Boiling of Ammonia on Vertical Flat Plate

    NASA Astrophysics Data System (ADS)

    Kim, Jeong-Hun; Arima, Hirofumi; Ikegami, Yasuyuki

    In the present study, the fundamental experiments that investigate characteristics of local heat transfer in forced convective boiling on vertical flat plate with 2-mm channel height are taken to realize plate type compact evaporator for OTEC or STEC. The experiments are performed with ammonia as the working fluid. The experiments are also carried out with the following test conditions; saturated pressure = 0.7, 0.8, 0.9 MPa, mass flux = 7.5, 10, 15 kg/(m2•s), heat flux = 15, 20, 25 kW/m2 and inlet quality = 0.1 ~ 0.4 [-]. The result shows that the wall superheated temperature of forced convective boiling is lower than that of pool boiling. And the heat transfer coefficient increases with an increase in quality and the decrease in the local heat flux and saturated pressure for prescribed experimental conditions. However, local heat transfer coefficients are not affected by mass fluxes in the prescribed experimental conditions. An empirical correlation that can predict the local heat transfer coefficient on vertical flat plate within experimental conditions is also proposed.

  10. Heat transfer to water from a vertical tube bundle under natural-circulation conditions. [PWR; BWR

    SciTech Connect

    Gruszczynski, M.J.; Viskanta, R.

    1983-01-01

    The natural circulation heat transfer data for longitudinal flow of water outside a vertical rod bundle are needed for developing correlations which can be used in best estimate computer codes to model thermal-hydraulic behavior of nuclear reactor cores under accident or shutdown conditions. The heat transfer coefficient between the fuel rod surface and the coolant is the key parameter required to predict the fuel temperature. Because of the absence of the required heat transfer coefficient data base under natural circulation conditions, experiments have been performed in a natural circulation loop. A seven-tube bundle having a pitch-to-diameter ratio of 1.25 was used as a test heat exchanger. A circulating flow was established in the loop, because of buoyancy differences between its two vertical legs. Steady-state and transient heat transfer measurements have been made over as wide a range of thermal conditions as possible with the system. Steady state heat transfer data were correlated in terms of relevant dimensionless parameters. Empirical correlations for the average Nusselt number, in terms of Reynolds number, Rayleigh number and the ratio of Grashof to Reynolds number are given.

  11. Impact of cosmological satellites on the vertical heating of the Milky Way disc

    NASA Astrophysics Data System (ADS)

    Moetazedian, R.; Just, A.

    2016-07-01

    We present a high-resolution study of the impact of realistic satellite galaxies, extracted from cosmological simulations of Milky Way haloes including 6 Aquarius suites and Via Lactea II, on the dynamics of the Galactic disc. The initial conditions for the multicomponent Milky Way galaxy were generated using the GALIC code, to ensure a system in dynamical equilibrium state prior to addition of satellites. Candidate subhaloes that came closer than 25 kpc to the centre of the host dark matter haloes with initial mass enclosed within the tidal radius, Mtid ≥ 108 M⊙ = 0.003 Mdisc, were identified, inserted into our high-resolution N-body simulations and evolved for 2 Gyr. We quantified the vertical heating due to such impacts by measuring the disc thickness and squared vertical velocity dispersion σ z2 across the disc. According to our analysis, the strength of heating is strongly dependent on the high-mass end of the subhalo distribution from cosmological simulations. The mean increase of the vertical dispersion is ˜20 km2 s-2 Gyr-1 for R > 4 kpc with a flat radial profile while, excluding Aq-F2 results, the mean heating is < 12 km2 s-2 Gyr-1, corresponding to 28 and 17 per cent of the observed vertical heating rate in the solar neighbourhood. Taking into account the statistical dispersion around the mean, we miss the observed heating rate by more than 3σ. We observed a general flaring of the disc height in the case of all seven simulations in the outer disc.

  12. Heat Dissipation Interfaces Based on Vertically Aligned Diamond/Graphite Nanoplatelets.

    PubMed

    Santos, N F; Holz, T; Santos, T; Fernandes, A J S; Vasconcelos, T L; Gouvea, C P; Archanjo, B S; Achete, C A; Silva, R F; Costa, F M

    2015-11-11

    Crystalline carbon-based materials are intrinsically chemically inert and good heat conductors, allowing their applications in a great variety of devices. A technological step forward in heat dissipators production can be given by tailoring the carbon phase microstructure, tuning the CVD synthesis conditions. In this work, a rapid bottom-up synthesis of vertically aligned hybrid material comprising diamond thin platelets covered by a crystalline graphite layer was developed. A single run was designed in order to produce a high aspect ratio nanostructured carbon material favoring the thermal dissipation under convection-governed conditions. The produced material was characterized by multiwavelength Raman spectroscopy and electron microscopy (scanning and transmission), and the macroscopic heat flux was evaluated. The results obtained confirm the enhancement of heat dissipation rate in the developed hybrid structures, when compared to smooth nanocrystalline diamond films.

  13. Unsteady Boundary Layer Flow and Heat Transfer of a Casson Fluid past an Oscillating Vertical Plate with Newtonian Heating

    PubMed Central

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter. PMID:25302782

  14. Unsteady boundary layer flow and heat transfer of a Casson fluid past an oscillating vertical plate with Newtonian heating.

    PubMed

    Hussanan, Abid; Zuki Salleh, Mohd; Tahar, Razman Mat; Khan, Ilyas

    2014-01-01

    In this paper, the heat transfer effect on the unsteady boundary layer flow of a Casson fluid past an infinite oscillating vertical plate with Newtonian heating is investigated. The governing equations are transformed to a systems of linear partial differential equations using appropriate non-dimensional variables. The resulting equations are solved analytically by using the Laplace transform method and the expressions for velocity and temperature are obtained. They satisfy all imposed initial and boundary conditions and reduce to some well-known solutions for Newtonian fluids. Numerical results for velocity, temperature, skin friction and Nusselt number are shown in various graphs and discussed for embedded flow parameters. It is found that velocity decreases as Casson parameters increases and thermal boundary layer thickness increases with increasing Newtonian heating parameter.

  15. Experimental study on condensation heat transfer of steam on vertical titanium plates with different surface energies

    SciTech Connect

    Baojin, Qi; Li, Zhang; Hong, Xu; Yan, Sun

    2011-01-15

    Visual experiments were employed to investigate heat transfer characteristics of steam on vertical titanium plates with/without surface modifications for different surface energies. Stable dropwise condensation and filmwise condensation were achieved on two surface modification titanium plates, respectively. Dropwise and rivulet filmwise co-existing condensation form of steam was observed on unmodified titanium surfaces. With increase in the surface subcooling, the ratio of area ({eta}) covered by drops decreased and departure diameter of droplets increased, resulting in a decrease in condensation heat transfer coefficient. Condensation heat transfer coefficient decreased sharply with the values of {eta} decreasing when the fraction of the surface area covered by drops was greater than that covered by rivulets. Otherwise, the value of {eta} had little effect on the heat transfer performance. Based on the experimental phenomena observed, the heat flux through the surface was proposed to express as the sum of the heat flux through the dropwise region and rivulet filmwise region. The heat flux through the whole surface was the weighted mean value of the two regions mentioned above. The model presented explains the gradual change of heat transfer coefficient for transition condensation with the ratio of area covered by drops. The simulation results agreed well with the present experimental data when the subcooling temperature is lower than 10 C. (author)

  16. Influence of fluid-property variation on turbulent convective heat transfer in vertical annular channel flows.

    SciTech Connect

    D. M. McEligot; J. H. Bae; J. Y. Yoo; H. Choi; James R. Wolf

    2005-10-01

    Influence of strongly-varying properties of supercritical-pressure fluids on turbulent convective heat transfer is investigated using direct numerical simulation. We consider thermally-developing upward flows in a vertical annular channel where the inner wall is heated with a constant heat flux and the outer wall is insulated. CO2 is chosen as the working fluid at a pressure to 8 Mpa, and the inlet Reynolds number based on the channel hydraulic diameter and the bulk velocity is Re0 = 8900. It is shown that turbulent convective heat transfer characteristics of supercritical flow are significantly different from those of constant-property flow mainly due to spatial and temporal variations of fluid density. Non-uniform density distribution causes fluid particles to be accelerated either by expansion or buoyancy force near the heated wall, while temporal density fluctuations change the transport characteristics of turbulent heat and momentum via the buoyancy production terms arising from the correlations such as p1u1x, p1u1r and p1h1. Among various turbulence statistics, the streamwise turbulent heat flux shows a very peculiar transitional behavior due to the buoyancy effect, changing both in sign and magnitude. Consequently, a non-monotonic temperature distribution is developed in the flow direction, causing severe impairment of heat transfer in supercritical flows.

  17. Vertical disc heating in Milky Way-sized galaxies in a cosmological context

    NASA Astrophysics Data System (ADS)

    Grand, Robert J. J.; Springel, Volker; Gómez, Facundo A.; Marinacci, Federico; Pakmor, Rüdiger; Campbell, David J. R.; Jenkins, Adrian

    2016-06-01

    Vertically extended, high velocity dispersion stellar distributions appear to be a ubiquitous feature of disc galaxies, and both internal and external mechanisms have been proposed to be the major driver of their formation. However, it is unclear to what extent each mechanism can generate such a distribution, which is likely to depend on the assembly history of the galaxy. To this end, we perform 16 high-resolution cosmological-zoom simulations of Milky Way-sized galaxies using the state-of-the-art cosmological magnetohydrodynamical code AREPO, and analyse the evolution of the vertical kinematics of the stellar disc in connection with various heating mechanisms. We find that the bar is the dominant heating mechanism in most cases, whereas spiral arms, radial migration and adiabatic heating from mid-plane density growth are all subdominant. The strongest source, though less prevalent than bars, originates from external perturbations from satellites/subhaloes of masses log10(M/M⊙) ≳ 10. However, in many simulations the orbits of newborn star particles become cooler with time, such that they dominate the shape of the age-velocity dispersion relation and overall vertical disc structure unless a strong external perturbation takes place.

  18. Experimental study of mixed convection heat transfer in vertical helically coiled tube heat exchangers

    SciTech Connect

    Ghorbani, N.; Taherian, H.; Gorji, M.; Mirgolbabaei, H.

    2010-10-15

    In this study the mixed convection heat transfer in a coil-in-shell heat exchanger for various Reynolds numbers, various tube-to-coil diameter ratios and different dimensionless coil pitch was experimentally investigated. The experiments were conducted for both laminar and turbulent flow inside coil. Effects of coil pitch and tube diameters on shell-side heat transfer coefficient of the heat exchanger were studied. Different characteristic lengths were used in various Nusselt number calculations to determine which length best fits the data and several equations were proposed. The particular difference in this study in comparison with the other similar studies was the boundary conditions for the helical coils. The results indicate that the equivalent diameter of shell is the best characteristic length. (author)

  19. Natural convection on a vertical plate in a saturated porous medium with internal heat generation

    NASA Astrophysics Data System (ADS)

    Guedda, M.; Sriti, M.; Achemlal, D.

    2014-08-01

    The main goal of this paper is to re-exam a class of exact solutions for the two-dimensional free convection boundary layers induced by a heated vertical plate embedded in a saturated porous medium with an exponential decaying heat generation. The temperature distribution of the plate has been assumed to vary as a power of the axial coordinate measured from the leading edge of the plate and subjected to an applied lateral mass flux. The boundary layer equations are solved analytically and numerically using a fifth-order Runge-Kutta scheme coupled with the shooting iteration method. As for the classical problem without internal heat generation, it is proved that multiple (unbounded) solutions arise for any and for any suction/injection parameter. For such solutions, the asymptotic behavior as the similarity variable approaches infinity is determined.

  20. Grouting for vertical geothermal heat pump systems: Engineering design and field procedures manual. Final report

    SciTech Connect

    1997-12-01

    Grouting of the vertical ground heat exchanger is important for environmental and heat transfer reasons, and is generally accomplished by the placement of a low permeability material into the annular space between the borehole wall and the pipes suspended in the borehole. Backfilling is the practice of placing drill cuttings or other materials into the annular volume, with no specific effort directed toward creating a hydraulic seal. State and local regulations dictate the need for grouting versus backfilling. This manual concentrates on the technical aspects of grouting, including the environmental issues related to grouting, the thermal characteristics of different grouting materials and how the design must account for those, and the practical aspects of grouting for the field technician. Formation conditions are presented where grouting is necessary to assure the quality of the potable water source, while other conditions are cited where only portions of the borehole need to be grouted. Thermal properties of several grouting materials, both bentonite-based and cement-based, are provided as input data to the calculation of borehole thermal resistance. A procedure is provided for the designer of a vertical ground heat exchanger to calculate borehole thermal resistance, and techniques are described to utilize those values in commonly used commercial design software packages. Several sets of field verification data are presented which indicate that the borehole thermal resistance design data are relevant and important in the performance of the vertical u-bend heat exchanger. Finally, procedures are described for the field technician for mixing equipment, pump, and tremie pipe selection. Methods to estimate the volume of grout required for a job are provided. Recommended field procedures for tremie installation and the grouting process are also provided.

  1. Experimental investigation on the heat transfer characteristics and flow pattern in vertical narrow channels heated from one side

    NASA Astrophysics Data System (ADS)

    Huang, Lihao; Li, Gang; Tao, Leren

    2016-07-01

    Experimental investigation for the flow boiling of water in a vertical rectangular channel was conducted to reveal the boiling heat transfer mechanism and flow patterns map aspects. The onset of nucleate boiling went upward with the increasing of the working fluid mass flow rate or the decreasing of the inlet working fluid temperature. As the vapour quality was increased, the local heat transfer coefficient increased first, then decreased, followed by various flow patterns. The test data from other researchers had a similar pattern transition for the bubble-slug flow and the slug-annular flow. Flow pattern transition model analysis was performed to make the comparison with current test data. The slug-annular and churn-annular transition models showed a close trend with current data except that the vapor phase superficial velocity of flow pattern transition was much higher than that of experimental data.

  2. Natural convection heat transfer of nanofluids along a vertical plate embedded in porous medium.

    PubMed

    Uddin, Ziya; Harmand, Souad

    2013-02-07

    The unsteady natural convection heat transfer of nanofluid along a vertical plate embedded in porous medium is investigated. The Darcy-Forchheimer model is used to formulate the problem. Thermal conductivity and viscosity models based on a wide range of experimental data of nanofluids and incorporating the velocity-slip effect of the nanoparticle with respect to the base fluid, i.e., Brownian diffusion is used. The effective thermal conductivity of nanofluid in porous media is calculated using copper powder as porous media. The nonlinear governing equations are solved using an unconditionally stable implicit finite difference scheme. In this study, six different types of nanofluids have been compared with respect to the heat transfer enhancement, and the effects of particle concentration, particle size, temperature of the plate, and porosity of the medium on the heat transfer enhancement and skin friction coefficient have been studied in detail. It is found that heat transfer rate increases with the increase in particle concentration up to an optimal level, but on the further increase in particle concentration, the heat transfer rate decreases. For a particular value of particle concentration, small-sized particles enhance the heat transfer rates. On the other hand, skin friction coefficients always increase with the increase in particle concentration and decrease in nanoparticle size.

  3. Mechanism of enhancement/deterioration of boiling heat transfer using stable nanoparticle suspensions over vertical tubes

    NASA Astrophysics Data System (ADS)

    Narayan, G. Prakash; Anoop, K. B.; Das, Sarit K.

    2007-10-01

    Boiling heat transfer using nanofluids has been a subject of a few investigations in the past few years and incongruous results have been reported in literature regarding the same. Conflicting explanations for deterioration of pool boiling heat transfer coefficient at higher concentrations (4-16wt%) have been presented by various researchers. Recently, a few works have reported a significant enhancement in pool boiling heat transfer coefficient at lower concentrations (0.32-1.25wt%) and the physical reasons for this have not been explained. The present work is aimed at removing these ambiguities. Experiments have been carried out by using stable water based nanofluids containing alumina nanoparticles (average sizes of 47 and 150nm) with vertical tubular heaters of various surface roughnesses (48, 98, and 524nm). It has been observed that with the rough heater (Ra=524nm), heat transfer is significantly enhanced and the enhancement reaches ˜70% at a particle loading of 0.5wt%. With the smooth heater (Ra=48nm), heat transfer is significantly deteriorated and the heat flux reduction reaches ˜45% at a particle loading of 2wt%. Further, it has been observed that a parameter which is the ratio of average size of the particle to the average roughness value of the heater can explain the reported controversy in the pool boiling behavior of these suspensions.

  4. Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel

    PubMed Central

    Gul, Aaiza; Khan, Ilyas; Shafie, Sharidan; Khalid, Asma; Khan, Arshad

    2015-01-01

    This study investigated heat transfer in magnetohydrodynamic (MHD) mixed convection flow of ferrofluid along a vertical channel. The channel with non-uniform wall temperatures was taken in a vertical direction with transverse magnetic field. Water with nanoparticles of magnetite (Fe3O4) was selected as a conventional base fluid. In addition, non-magnetic (Al2O3) aluminium oxide nanoparticles were also used. Comparison between magnetic and magnetite nanoparticles were also conducted. Fluid motion was originated due to buoyancy force together with applied pressure gradient. The problem was modelled in terms of partial differential equations with physical boundary conditions. Analytical solutions were obtained for velocity and temperature. Graphical results were plotted and discussed. It was found that temperature and velocity of ferrofluids depend strongly on viscosity and thermal conductivity together with magnetic field. The results of the present study when compared concurred with published work. PMID:26550837

  5. Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel.

    PubMed

    Gul, Aaiza; Khan, Ilyas; Shafie, Sharidan; Khalid, Asma; Khan, Arshad

    2015-01-01

    This study investigated heat transfer in magnetohydrodynamic (MHD) mixed convection flow of ferrofluid along a vertical channel. The channel with non-uniform wall temperatures was taken in a vertical direction with transverse magnetic field. Water with nanoparticles of magnetite (Fe3O4) was selected as a conventional base fluid. In addition, non-magnetic (Al2O3) aluminium oxide nanoparticles were also used. Comparison between magnetic and magnetite nanoparticles were also conducted. Fluid motion was originated due to buoyancy force together with applied pressure gradient. The problem was modelled in terms of partial differential equations with physical boundary conditions. Analytical solutions were obtained for velocity and temperature. Graphical results were plotted and discussed. It was found that temperature and velocity of ferrofluids depend strongly on viscosity and thermal conductivity together with magnetic field. The results of the present study when compared concurred with published work. PMID:26550837

  6. Heat Transfer in MHD Mixed Convection Flow of a Ferrofluid along a Vertical Channel.

    PubMed

    Gul, Aaiza; Khan, Ilyas; Shafie, Sharidan; Khalid, Asma; Khan, Arshad

    2015-01-01

    This study investigated heat transfer in magnetohydrodynamic (MHD) mixed convection flow of ferrofluid along a vertical channel. The channel with non-uniform wall temperatures was taken in a vertical direction with transverse magnetic field. Water with nanoparticles of magnetite (Fe3O4) was selected as a conventional base fluid. In addition, non-magnetic (Al2O3) aluminium oxide nanoparticles were also used. Comparison between magnetic and magnetite nanoparticles were also conducted. Fluid motion was originated due to buoyancy force together with applied pressure gradient. The problem was modelled in terms of partial differential equations with physical boundary conditions. Analytical solutions were obtained for velocity and temperature. Graphical results were plotted and discussed. It was found that temperature and velocity of ferrofluids depend strongly on viscosity and thermal conductivity together with magnetic field. The results of the present study when compared concurred with published work.

  7. Vertical channel free convection for a power law fluid with a constant heat flux

    SciTech Connect

    Irvine, T.F. Jr.; Schneider, W.J.

    1984-08-08

    The development of free convection in a purely viscous non-newtonian fluid under the influence of a uniform wall heat flux is investigated. A finite difference solution is presented of the velocity and temperature profiles for the flow of an Ostwald-de Waele (power law) fluid between two symmetrically heated vertical plates. The flow, temperature and heat transfer characteristics of the channel are presented in a dimensionless manner as related to the generalized Grashof and Prandtl numbers and the fully developed flow range is established. The numerical solutions for the developing flow are shown to approach two classical asymptotes - fully developed duct free convection at low Rayleigh numbers and two independent vertical plates at high Rayleigh numbers. A comparison is made between the results of this theoretical investigation and previously published analytical and experimental work on newtonian and non-newtonian fluids. The results and their application to engineering problems are discussed. The changes caused by the addition of soluble substances to water cause significant variations in the mean flow between the plates and in the outlet temperature.

  8. Two-phase distribution in the vertical flow line of a domestic wet central heating system

    NASA Astrophysics Data System (ADS)

    Fsadni, A.-M.; Ge, Y. T.

    2013-04-01

    The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi homogenous across the pipe section with a negligible reduction in the void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.

  9. Potential vertical movement of large heat-generating waste packages in salt.

    SciTech Connect

    Clayton, Daniel James; Martinez, Mario J.; Hardin, Ernest.

    2013-05-01

    With renewed interest in disposal of heat-generating waste in bedded or domal salt formations, scoping analyses were conducted to estimate rates of waste package vertical movement. Vertical movement is found to result from thermal expansion, from upward creep or heave of the near-field salt, and from downward buoyant forces on the waste package. A two-pronged analysis approach was used, with thermal-mechanical creep modeling, and coupled thermal-viscous flow modeling. The thermal-mechanical approach used well-studied salt constitutive models, while the thermal-viscous approach represented the salt as a highly viscous fluid. The Sierra suite of coupled simulation codes was used for both approaches. The waste package in all simulations was a right-circular cylinder with the density of steel, in horizontal orientation. A time-decaying heat generation function was used to represent commercial spent fuel with typical burnup and 50-year age. Results from the thermal-mechanical base case showed approximately 27 cm initial uplift of the package, followed by gradual relaxation closely following the calculated temperature history. A similar displacement history was obtained with the package density set equal to that of salt. The slight difference in these runs is attributable to buoyant displacement (sinking) and is on the order of 1 mm in 2,000 years. Without heat generation the displacement stabilizes at a fraction of millimeter after a few hundred years. Results from thermal-viscous model were similar, except that the rate of sinking was constant after cooldown, at approximately 0.15 mm per 1,000 yr. In summary, all calculations showed vertical movement on the order of 1 mm or less in 2,000 yr, including calculations using well-established constitutive models for temperature-dependent salt deformation. Based on this finding, displacement of waste packages in a salt repository is not a significant repository performance issue.

  10. Characterization of heat loads from mitigated and unmitigated vertical displacement events in DIII-D

    SciTech Connect

    Hollmann, E. M.; Moyer, R. A.; Commaux, N.; Jernigan, T. J.; Eidietis, N. W.; Humphreys, D. A.; Strait, E. J.; Wesley, J. C.; Lasnier, C. J.; Pitts, R. A.; Sugihara, M.; Watkins, J.

    2013-06-15

    Experiments have been conducted on the DIII-D tokamak to study the distribution and repeatability of heat loads and vessel currents resulting from vertical displacement events (VDEs). For unmitigated VDEs, the radiated power fraction appears to be of order 50%, with the remaining power dominantly conducted to the vessel walls. Shot-to-shot scatter in heat loads measured at one toroidal location is not large (<±50%), suggesting that toroidal asymmetries in conducted heat loads are not large. Conducted heat loads are clearly observed during the current quench (CQ) of both mitigated and unmitigated disruptions. Significant poloidal asymmetries in heat loads and radiated power are often observed in the experiments but are not yet understood. Energy dissipated resistively in the conducting walls during the CQ appears to be small (<5%). The mitigating effect of neon massive gas injection (MGI) as a function of MGI trigger delay has also been studied. Improved mitigation is observed as the MGI trigger delay is decreased. For sufficiently early MGI mitigation, close to 100% radiated energy and a reduction of roughly a factor 2 in vessel forces is achieved.

  11. Pioneering Heat Pump Project

    SciTech Connect

    Aschliman, Dave; Lubbehusen, Mike

    2015-06-30

    This project was initiated at a time when ground coupled heat pump systems in this region were limited in size and quantity. There were economic pressures with costs for natural gas and electric utilities that had many organizations considering ground coupled heat pumps; The research has added to the understanding of how ground temperatures fluctuate seasonally and how this affects the performance and operation of the heat pumps. This was done by using a series of temperature sensors buried within the middle of one of the vertical bore fields with sensors located at various depths below grade. Trending of the data showed that there is a lag in ground temperature with respect to air temperatures in the shoulder months, however as full cooling and heating season arrives, the heat rejection and heat extraction from the ground has a significant effect on the ground temps; Additionally it is better understood that while a large community geothermal bore field serving multiple buildings does provide a convenient central plant to use, it introduces complexity of not being able to easily model and predict how each building will contribute to the loads in real time. Additional controllers and programming were added to provide more insight into this real time load profile and allow for intelligent shedding of load via a dry cooler during cool nights in lieu of rejecting to the ground loop. This serves as a means to ‘condition’ the ground loop and mitigate thermal creep of the field, as is typically observed; and It has been observed when compared to traditional heating and cooling equipment, there is still a cost premium to use ground source heat pumps that is driven mostly by the cost for vertical bore holes. Horizontal loop systems are less costly to install, but do not perform as well in this climate zone for heating mode

  12. An Algorithm to Estimate the Heating Budget from Vertical Hydrometeor Profiles.

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Simpson, Joanne; Lang, Stephen; McCumber, Michael; Adler, Robert; Penc, Richard

    1990-12-01

    A simple algorithm to estimate the latent heating of cloud systems from their vertical hydrometer profiles is proposed. The derivation as well as the validation of the algorithm is based on output generated by a non-hydrostatic cloud model with parameterized microphysical processes. Mature and decaying stages of a GATE squall-type convective system have been tested. The algorithm-derived heating budget is in reasonable agreement with the budget predicted by the cloud model. The input to the proposed algorithm can be obtained from either a rain retrieval technique based on information from multichannel passive microwave signals or a kinematic cloud model based on information from Doppler radar wind fields and radar reflectivity patterns. Such an application would have significant implications for spaceborne remote sensing and the large-scale weather prediction data assimilation problem.

  13. Effect of segmental heating on mixed convection aiding flow in a vertical porous annulus

    NASA Astrophysics Data System (ADS)

    Salman, Ahmed N. J.; Al-Rashed, Abdullah A. A. A.; Kamangar, Sarfaraz; Khan, T. M. Yunus; Khaleed, H. M. T.

    2016-06-01

    Mixed convection flow in a vertical porous annulus embedded with fluid saturated porous medium for aiding is investigated. The annulus is imposed by 20%, 35% and 50% heater length at the bottom, mid and top sections of the annulus respectively. Darcy law with thermal non-equilibrium approach is considered. The governing partial differential equations are converted to simple algebraic equations using Finite Element Method (FEM). The effects of Peclet number Pe and conductivity ratio Kr on heat transfer and fluid flow behaviour are examined and it is found that for lower conductivity ratio, the heat transfer rate was higher with the increase in the Peclet number Pe, whereas this trend reversed when thermal conductivity ratio Kr is increased.

  14. The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Devasthale, A.; L'Ecuyer, T.; Ekman, A. M. L.; Tjernström, M.

    2015-10-01

    Clouds forming during the summer monsoon over the Indian subcontinent affect its evolution through their radiative impact as well as the release of latent heat. While the latter is previously studied to some extent, comparatively little is known about the radiative impact of different cloud types and the vertical structure of their radiative heating/cooling effects. Therefore, the main aim of this study is to partly fill this knowledge gap by investigating and documenting the vertical distributions of the different cloud types associated with the Indian monsoon and their radiative heating/cooling using the active radar and lidar sensors onboard CloudSat and CALIPSO. The intraseasonal evolution of clouds from May to October is also investigated to understand pre-to-post monsoon transitioning of their radiative heating/cooling effects. The vertical structure of cloud radiative heating (CRH) follows the northward migration and retreat of the monsoon from May to October. Throughout this time period, stratiform clouds radiatively warm the middle troposphere and cool the upper troposphere by more than ±0.2 K day-1 (after weighing by cloud fraction), with the largest impacts observed in June, July and August. During these months, the fraction of high thin cloud remains high in the tropical tropopause layer (TTL). Deep convective towers cause considerable radiative warming in the middle and upper troposphere, but strongly cool the base and inside of the TTL. This cooling is stronger during active (-1.23 K day-1) monsoon periods compared to break periods (-0.36 K day-1). The contrasting radiative warming effect of high clouds in the TTL is twice as large during active periods than in break periods. These results highlight the increasing importance of CRH with altitude, especially in the TTL. Stratiform (made up of alto- and nimbostratus clouds) and deep convection clouds radiatively cool the surface by approximately -100 and -400 W m-2 respectively while warming the

  15. Effect of rolling motion on critical heat flux for subcooled flow boiling in vertical tube

    SciTech Connect

    Hwang, J. S.; Park, I. U.; Park, M. Y.; Park, G. C.

    2012-07-01

    This paper presents defining characteristics of the critical heat flux (CHF) for the boiling of R-134a in vertical tube operation under rolling motion in marine reactor. It is important to predict CHF of marine reactor having the rolling motion in order to increase the safety of the reactor. Marine Reactor Moving Simulator (MARMS) tests are conducted to measure the critical heat flux using R-134a flowing upward in a uniformly heated vertical tube under rolling motion. MARMS was rotated by motor and mechanical power transmission gear. The CHF tests were performed in a 9.5 mm I.D. test section with heated length of 1 m. Mass fluxes range from 285 to 1300 kg m{sup -2}s{sup -1}, inlet subcooling from 3 to 38 deg. C and outlet pressures from 13 to 24 bar. Amplitudes of rolling range from 15 to 40 degrees and periods from 6 to 12 sec. To convert the test conditions of CHF test using R-134a in water, Katto's fluid-to-fluid modeling was used in present investigation. A CHF correlation is presented which accounts for the effects of pressure, mass flux, inlet subcooling and rolling angle over all conditions tested. Unlike existing transient CHF experiments, CHF ratio of certain mass flux and pressure are different in rolling motion. For the mass fluxes below 500 kg m{sup -2}s{sup -1} at 13, 16 (region of relative low mass flux), CHF ratio was decreased but was increased above that mass flux (region of relative high mass flux). Moreover, CHF tend to enhance in entire mass flux at 24 bar. (authors)

  16. Vertical profiles of aerosol optical properties and the solar heating rate estimated by combining sky radiometer and lidar measurements

    NASA Astrophysics Data System (ADS)

    Kudo, Rei; Nishizawa, Tomoaki; Aoyagi, Toshinori

    2016-07-01

    The SKYLIDAR algorithm was developed to estimate vertical profiles of aerosol optical properties from sky radiometer (SKYNET) and lidar (AD-Net) measurements. The solar heating rate was also estimated from the SKYLIDAR retrievals. The algorithm consists of two retrieval steps: (1) columnar properties are retrieved from the sky radiometer measurements and the vertically mean depolarization ratio obtained from the lidar measurements and (2) vertical profiles are retrieved from the lidar measurements and the results of the first step. The derived parameters are the vertical profiles of the size distribution, refractive index (real and imaginary parts), extinction coefficient, single-scattering albedo, and asymmetry factor. Sensitivity tests were conducted by applying the SKYLIDAR algorithm to the simulated sky radiometer and lidar data for vertical profiles of three different aerosols, continental average, transported dust, and pollution aerosols. The vertical profiles of the size distribution, extinction coefficient, and asymmetry factor were well estimated in all cases. The vertical profiles of the refractive index and single-scattering albedo of transported dust, but not those of transported pollution aerosol, were well estimated. To demonstrate the performance and validity of the SKYLIDAR algorithm, we applied the SKYLIDAR algorithm to the actual measurements at Tsukuba, Japan. The detailed vertical structures of the aerosol optical properties and solar heating rate of transported dust and smoke were investigated. Examination of the relationship between the solar heating rate and the aerosol optical properties showed that the vertical profile of the asymmetry factor played an important role in creating vertical variation in the solar heating rate. We then compared the columnar optical properties retrieved with the SKYLIDAR algorithm to those produced with the more established scheme SKYRAD.PACK, and the surface solar irradiance calculated from the SKYLIDAR

  17. Cloud vertical structure, radiative heating profile and diurnal variation during TOGA COARE

    NASA Astrophysics Data System (ADS)

    Qian, Taotao

    This thesis consists of two parts: (1) the vertical structure of clouds and radiative heating during TOGA COARE and (2) diurnal variations during TOGA COARE. The purpose of the first part (Chapter 1) is to determine a realistic gridded (1 degree by 1 degree) cloud vertical structure and radiative heating profile for the Intensive Flux Array (IFA) during the Tropical Ocean Global Atmosphere (TOGA) Coupled Ocean Atmosphere Response Experiment (COARE). First, we deduce the cloud vertical structure from the sounding data using an improved relative humidity (RH) threshold method. The RH threshold is height-dependent and is tuned by three surface and TOA observations of clouds: the Micropulse Lidar (MPL), the High-Resolution Infrared Sounder (HIRS) and the International Satellite Cloud Climatology Project (ISCCP). Then, a modified CCM3 Column Radiation Model (CRM) is used to calculate the radiative heating profiles. The modification of the CRM replaces the model microphysics with the observed microphysics profiles. The calculated radiation budgets are shown to be consistent with the surface and top of the atmosphere (TOA) observations and are much better than those of the standard version of the CRM. The purpose of the second part (Chapter 2) is to test different diurnal variation mechanisms, that have been proposed in previous studies, by using the abundant observational data obtained during TOGA COARE. The preliminary findings are: (1) The stratiform precipitation lags the convective precipitation, suggesting that the effect of the life cycle of the mesoscale convective systems (MCS) is important to the midnight rainfall maximum; i.e., the stratiform component helps to shift the maximum toward midnight. This supports the MCS life cycle mechanism. (2) This study supports the direct radiation-convection interaction mechanism and emphasize that the variation is strongly affected by the variation of upper-level clouds. (3) The current study does not, however, support the

  18. The vertical structure of cloud radiative heating over the Indian subcontinent during summer monsoon

    NASA Astrophysics Data System (ADS)

    Johansson, E.; Devasthale, A.; L'Ecuyer, T.; Ekman, A. M. L.; Tjernström, M.

    2015-02-01

    Every year the monsoonal circulation over the Indian subcontinent gives rise to a variety of cloud types that differ considerably in their ability to heat or cool the atmosphere. These clouds in turn affect monsoon dynamics via their radiative impacts, both at the surface and in the atmosphere. New generation of satellites carrying active radar and lidar sensors are allowing realistic quantification of cloud radiative heating (CRH) by resolving the vertical structure of the atmosphere in an unprecedented detail. Obtaining this information is a first step in closing the knowledge gap in our understanding of the role that different clouds play as regulators of the monsoon and vice versa. Here, we use collocated CloudSat-CALIPSO data sets to understand following aspects of cloud-radiation interactions associated with Indian monsoon circulation. (1) How does the vertical distribution of CRH evolve over the Indian continent throughout monsoon season? (2) What is the absolute contribution of different clouds types to the total CRH? (3) How do active and break periods of monsoon affect the distribution of CRH? And finally, (4) what are the net radiative effects of different cloud types on surface heating? In general, the vertical structure of CRH follows the northward migration and the retreat of monsoon from May to October. It is found that the alto- and nimbostratus clouds intensely warm the middle troposphere and equally strongly cool the upper troposphere. Their warming/cooling consistently exceeds ±0.2 K day-1 (after weighing by vertical cloud fraction) in monthly mean composites throughout the middle and upper troposphere respectively, with largest impact observed in June, July and August. Deep convective towers cause considerable warming in the middle and upper troposphere, but strongly cool the base and inside of the tropical tropopause layer (TTL). Such cooling is stronger during active (-1.23 K day-1) monsoon conditions compared to break periods (-0.36 K day-1

  19. Dynamics of the collision of a vortex ring with a vertical heated wall

    NASA Astrophysics Data System (ADS)

    Gelderblom, G.; Palacios-Morales, C. A.; Zenit, R.; Solorio-Ordaz, F. J.

    2012-11-01

    We study the dynamics of the impact of a vortex ring with a vertical heated plate (at constant temperature). Laminar vortex rings were generated with a piston cylinder arrangement. The vertical wall is heated by a thermal bath which is held at constant temperature producing a laminar and stable thermal boundary layer. Measurements of the 2D velocity field were obtained with a PIV technique. The experimental results for the isothermal case are in agreement with previous investigations reported in the literature. To avoid azimuthal instabilities, we mainly conducted experiments for L /D0 = 1 (where L is the piston displacement and D0 is the cylinder inner diameter) with different wall temperatures and vortex translation velocities. For this case, secondary vortices were not observed. Using ink visualization we observed the evolution of the vortex shape. The initial circular shape evolves into a ``cat head'' shape after reaching the wall. The top and bottom regions of the vortex reduce and increase their vorticity, respectively. The sides are stretched and convected. An analysis of the different mechanisms leading to this shape evolution is presented and discussed.

  20. Mixed Convection with Conduction and Surface Radiation from a Vertical Channel with Discrete Heating

    NASA Astrophysics Data System (ADS)

    Londhe, S. D.; Rao, C. G.

    2013-10-01

    A numerical investigation into fluid flow and heat transfer for the geometry of a vertical parallel plate channel subjected to conjugate mixed convection with radiation is attempted here. The channel considered has three identical flush-mounted discrete heat sources in its left wall, while the right wall that does not contain any heat source acts as a sink. Air, assumed to be a radiatively non-participating and having constant thermophysical properties subject to the Boussinesq approximation, is the cooling agent. The heat generated in the left wall gets conducted along it and is later dissipated by mixed convection and radiation. The governing equations, considered in their full strength sans the boundary layer approximations, are converted into vorticity-stream function form and are then normalized. These equations along with pertinent boundary conditions are solved through finite volume method coupled with Gauss-Seidel iterative technique. The effects of modified Richardson number, surface emissivity, thermal conductivity and aspect ratio on local temperature distribution along the channel, maximum channel temperature and relative contributions of mixed convection and radiation have been thoroughly studied. The prominence of radiation in the present problem has been highlighted.

  1. The effect of water subcooling on film boiling heat transfer from vertical cylinders

    SciTech Connect

    Greene, G.A.; Irvine, T.F. Jr.

    1994-03-01

    The effect of subcooling on the film boiling heat transfer of water from vertical copper cylinders has been investigated experimentally using a transient quench technique. A lumped parameter model was utilized since the Blot numbers were always less than 0.05. The amount of subcooling varied from 0 K to 70 K and the initial cylinder wall temperatures were of the order of 1100 K. Heat transfer coefficient were measured at the midpoint of the cylinders and were obtained over quench times in which they were verified to be constant. Subcooling had a significant effect on both the film boiling heat transfer coefficient and the minimum film boiling temperature. As the subcooling varied from 0 K to 70 K, the h transfer coefficient increased by a factor of five. As the subcooling varied from 0 K to 60 K, the minimum film boiling temperature increased from approximately 600 K to 1000 K. An attempt to correlate the heat transfer coefficient data with a method recently proposed by Sakurai et al. was only successful at subcooled temperature differences less than 10 K. A modified correlation is presented using the Sakurai et al. parameters which better represents the data over the complete subcooling range.

  2. Effects of Prandtl number on free convection heat transfer from a vertical plate to a non-Newtonian fluid

    SciTech Connect

    Huang, Mingjer; Huang, Jhyshean; Chou, Youli; Chen, Cha'okuang )

    1989-02-01

    A study has been conducted to analyze the heat transfer characteristics of non-Newtonian power law fluids on the free convective flow over a vertical flat plate. The analysis includes the inertia force in the momentum equation with a finite Prandtl number. In general, it has been found that the average heat transfer increases with increasing Prandtl number.

  3. On the vertical exchange of heat, mass and momentum over complex, mountainous terrain

    NASA Astrophysics Data System (ADS)

    Rotach, Mathias; Gohm, Alexander; Lang, Moritz; Leukauf, Daniel; Stiperski, Ivana; Wagner, Johannes

    2015-12-01

    The role of the atmospheric boundary layer (ABL) in the atmosphere-climate system is the exchange of heat, mass and momentum between 'the earth's surface' and the atmosphere. Traditionally, it is understood that turbulent transport is responsible for this exchange and hence the understanding and physical description of the turbulence structure of the boundary layer is key to assess the effectiveness of earth-atmosphere exchange. This understanding is rooted in the (implicit) assumption of a scale separation or spectral gap between turbulence and mean atmospheric motions, which in turn leads to the assumption of a horizontally homogeneous and flat (HHF) surface as a reference, for which both physical understanding and model parameterizations have successfully been developed over the years. Over mountainous terrain, however, the ABL is generically inhomogeneous due to both thermal (radiative) and dynamic forcing. This inhomogeneity leads to meso-scale and even sub-meso-scale flows such as slope and valley winds or wake effects. It is argued here that these (sub)meso-scale motions can significantly contribute to the vertical structure of the boundary layer and hence vertical exchange of heat and mass between the surface and the atmosphere. If model grid resolution is not high enough the latter will have to be parameterized (in a similar fashion as gravity wave drag parameterizations take into account the momentum transport due to gravity waves in large-scale models). In this contribution we summarize the available evidence of the contribution of (sub)meso-scale motions to vertical exchange in mountainous terrain from observational and numerical modeling studies. In particular, a number of recent simulation studies using idealized topography will be summarized and put into perspective – so as to identify possible limitations and areas of necessary future research.

  4. The study and development of the empirical correlations equation of natural convection heat transfer on vertical rectangular sub-channels

    NASA Astrophysics Data System (ADS)

    Kamajaya, Ketut; Umar, Efrizon; Sudjatmi, K. S.

    2012-06-01

    This study focused on natural convection heat transfer using a vertical rectangular sub-channel and water as the coolant fluid. To conduct this study has been made pipe heaters are equipped with thermocouples. Each heater is equipped with five thermocouples along the heating pipes. The diameter of each heater is 2.54 cm and 45 cm in length. The distance between the central heating and the pitch is 29.5 cm. Test equipment is equipped with a primary cooling system, a secondary cooling system and a heat exchanger. The purpose of this study is to obtain new empirical correlations equations of the vertical rectangular sub-channel, especially for the natural convection heat transfer within a bundle of vertical cylinders rectangular arrangement sub-channels. The empirical correlation equation can support the thermo-hydraulic analysis of research nuclear reactors that utilize cylindrical fuel rods, and also can be used in designing of baffle-free vertical shell and tube heat exchangers. The results of this study that the empirical correlation equations of natural convection heat transfer coefficients with rectangular arrangement is Nu = 6.3357 (Ra.Dh/x)0.0740.

  5. Performance prediction between horizontal and vertical source heat pump systems for greenhouse heating with the use of artificial neural networks

    NASA Astrophysics Data System (ADS)

    Benli, Hüseyin

    2016-08-01

    This paper presents the suitability of artificial neural networks (ANNs) to predict the performance and comparison between a horizontal and a vertical ground source heat pump system. Performance forecasting is the precondition for the optimal control and energy saving operation of heat pump systems. In this study, performance parameters such as air temperature entering condenser fan-coil unit, air temperature leaving condenser fan-coil unit, and ground temperatures (2 and 60 m) obtained experimental studies are input data; coefficient of performance of system (COPsys) is in output layer. The back propagation learning algorithm with three different variants such as Levenberg-Marguardt, Pola-Ribiere conjugate gradient, and scaled conjugate gradient, and also tangent sigmoid transfer function were used in the network so that the best approach can be found. The results showed that LM with three neurons in the hidden layer is the most suitable algorithm with maximum correlation coefficients R2 of 0.999, minimum root mean square RMS value and low coefficient variance COV. The reported results confirmed that the use of ANN for performance prediction of COPsys,H-V is acceptable in these studies.

  6. Numerical simulation of supercritical heat transfer under severe axial density gradient in a narrow vertical tube

    SciTech Connect

    Bae, Y. Y.; Hong, S. D.; Kim, Y. W.

    2012-07-01

    A number of computational works have been performed so far for the simulation of heat transfer in a supercritical fluid. The simulations, however, faced a lot of difficulties when heat transfer deteriorates due either to buoyancy or by acceleration. When the bulk temperature approaches the pseudo-critical temperature the fluid experiences a severe axial density gradient on top of a severe radial one. Earlier numerical calculations showed, without exception, unrealistic over-predictions, as soon as the bulk temperature exceeded the pseudo-critical temperature. The over-predictions might have been resulted from an inapplicability of widely-used turbulence models. One of the major causes for the difficulties may probably be an assumption of a constant turbulent Prandtl number. Recent research, both numerical and experimental, indicates that the turbulent Prandtl number is never a constant when the gradient of physical properties is significant. This paper describes the applicability of a variable turbulent Prandtl number to the numerical simulation of heat transfer in supercritical fluids flowing in narrow vertical tubes. (authors)

  7. Vertical Variations In Heat Flow Inferred From Experiments In Deep Boreholes

    NASA Astrophysics Data System (ADS)

    Popov, Y.; Romushkevich, R.; Gorobtsov, D.; Korobkov, D.

    2012-04-01

    Deep scientific and parametric continental boreholes allow to obtain representative experimental data on combination of the geothermal parameters of the crust - temperature, temperature gradient, rock thermal properties, and, as the result, heat flow density values - which are more reliable compared to the previous data from shallow boreholes. Special advantages of the scientific boreholes include also a possibility for many repeated temperature logging during long time intervals (several years often) after a finish of the drilling that allowed (1) to determine temperatures and temperature gradient values corresponding to thermal equilibrium of the formations studied, (2) to study temporal regularities in temperature and temperature gradient behaviour within different formation layers during the formation recovery process. Scientific boreholes are drilled with numerous coring (often - with continuous coring) that provides the possibility to obtain detailed information on a distribution of rock thermal conductivity along the borehole. As a result, the scientific deep and super-deep boreholes provided the unique possibility for the determination of vertical distributions of the heat flow density that can not be reached normally in other boreholes. Experimental geothermal and petrothermal investigations performed for the super-deep boreholes Kola, Ural, Vorotilovo, Tyumen, Yen-Yakha (all - Russia), Saatly (Azerbaidzhan), and deep scientific and parametric boreholes Kolva, Timano-Pechora, Tyrnyaus, (all - Russia), Krivoy Rog (Ukraine), Muruntau (Uzbekistan), Nordlingen-72 (Germany), Yaxcopoil-1 (Mexico) allowed us to establish the following important peculiarities in geothermal parameters of the crustal blocks studied with scientific deep drilling were established from the investigations: (1) temperature gradient recovery up to undisturbed values occurs essentially faster than it was assumed earlier; (2) a rate of temperature gradient recovery was found to be different

  8. The rapid growth of vertically aligned carbon nanotubes using laser heating.

    PubMed

    Park, J B; Jeong, S H; Jeong, M S; Lim, S C; Lee, I H; Lee, Y H

    2009-05-01

    Growth of densely packed vertically aligned carbon nanotubes (VA-CNTs) using laser-induced chemical vapor deposition with visible laser (lambda = 532 nm) irradiation at room temperature is reported. Using a multiple-catalyst layer (Fe/Al/Cr) on quartz as the substrate and an acetylene-hydrogen mixture as the precursor gas, VA-CNT pillars with 60 microm height and 4 microm diameter were grown at a high rate of around 1 microm s(-1) with good reproducibility. It is demonstrated that the fabrication of uniform pillar arrays of VA-CNTs can be achieved with a single irradiation for each pillar using LCVD with no annealing or preprocessing of the substrate. Here, laser fast heating is considered the primary mechanism facilitating the growth of VA-CNT pillars. Field emission characteristics of an array of VA-CNT pillars were then examined to investigate their potential application in vacuum electronic devices.

  9. Vertical Profiles of Latent Heating in TRMM: Validation and Assimilation in the GEOS Data Assimilation System. [Year 2001 Project Report

    NASA Technical Reports Server (NTRS)

    Zhang, Ming-Hua

    2001-01-01

    I have derived the vertical profiles of apparent heating Q and Q2 by using 3-hourly balloon sounding data from the ARM SGP sounding array for three IOPs in 2000. These IOPs cover the periods from 3/1 to 3/22, from 9/25 to 10/8, and from 11/27 to 12/22. These heating profiles will be collocated with the TRMM heating profiles for validation studies once the TRMM profiles become available to the investigators. I have also produced the objective analyses of Q1, Q2 and forcing fields for the international GCSS Case 3 Intercomparison project. The GSFC CRM participated in study, based on which TRMM heating profiles are derived. I have also studied to assimilate the vertical heating profile by constraining the cloud-base mass flux in the cumulus convection scheme using the CCM3. I first derive the vertical heating profile for each convective plume of unit cloud-base mass flux. The observed heating profile form ARM is then de-convoluted to derive the cloud base mass fluxes of all individual plumes. These fluxes are compared with those derived from the quasi-equilibrium hypothesis. They are shown to improve many other aspects of the model behavior.

  10. Experimental study on convective heat transfer coefficient around a vertical hexagonal rod bundle

    NASA Astrophysics Data System (ADS)

    Makhmalbaf, M. H. M.

    2012-06-01

    Research on convective heat transfer coefficient around a rod bundle has many diverse applications in industry. So far, many studies have been conducted in correlations related to internal and turbulent fully-developed flow. Comparison shows that Dittus-Boelter, Sieder-Tate and Petukhov have so far been the most practical correlations in fully-developed turbulent fluid flow heat transfer. The present study conducts an experimental examination of the validity of these frequently-applied correlations and introduces a manufactured test facility as well. Due to its generalizibility, the unique geometry of this test facility (hexagonal arranged, 7 vertical rods in a hexagonal tube) can fulfil extensive applications. The paper also studies the major deviation sources in data measurements, calibrations and turbulence of fluid flow in this. Finally, regarding to sufficient number of experiments in a vast fluid mean velocity range (3,800 < Re < 40,000), a new curve and correlation are presented and the results are compared with the above mentioned commonly-applied correlations.

  11. Buoyancy-driven flows of a radiatively participating fluid in a vertical cylinder heated from below

    NASA Technical Reports Server (NTRS)

    Salinger, A. G.; Brandon, S.; Aris, R.; Derby, J. J.

    1993-01-01

    The effect of radiative energy transport on the onset and evolution of natural convective flows is studied in a Rayleigh-Benard system. Steady, axisymmetric flows of a radiatively participating fluid contained in a rigid-walled, vertical cylinder which is heated on the base, cooled on top, and insulated on the side wall are calculated by using the Galerkin FEM. Bifurcation analysis techniques are used to investigate the changes in the flow structure due to internal radiation. The results of this two-parameter study - where the Rayleigh number, Ra and optical thickness, tau, are varied - apply to fluids ranging from opaque to nearly transparent with respect to IR radiation. For any nonopaque fluid, internal radiation eliminates the static state that without radiation, exists for all values of the Rayleigh number. This heat transfer mechanism also destroys a symmetry of the system that relates clockwise and counterclockwise flows. The connectivity between characteristic flow families and the range of Ra where families are stable are found to depend greatly on tau. Results demonstrate the inadequacy of characterizing the behavior of this system using simple notions of radiative transfer in optically thick or thin media; the nonlinear interaction of radiation and flow are far more complicated than these asymptotic limits would imply.

  12. The impact of vertical measurement depth on the information content of soil moisture for latent heat flux estimation

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Using ground-based soil moisture and latent/sensible heat fluxes observations acquired from the Ameriflux Network, we calculate the mutual information (MI) content between multiple soil moisture variables and evaporative fraction (EF) to examine the existence of information in vertically-integrated ...

  13. Natural convection characteristics of power-law fluids over a heated vertical plate of variable surface conditions

    SciTech Connect

    Erbas, S.; Ece, M.C.

    1999-07-01

    Fluids such as molten plastics, polymers, pulps, foodstuffs or slurries exhibit non-Newtonian fluid behavior and are increasingly used in various manufacturing and processing industries. Determination of the friction and heat transfer characteristics of non-Newtonian fluids over heated surfaces is important for the design of industrial equipment working with this type of fluids. Steady free convection laminar boundary-layer flow along a heated vertical plate immersed in a quiescent power-law fluid is investigated. Two heating modes are considered by assuming that either surface temperature or heat flux has a power-law variation. Similarity solutions of the boundary-layer equations are obtained numerically for both heating conditions. The skin friction coefficient and Nusselt number are found to be higher in the prescribed temperature case for large Prandtl numbers and increase with the flow behavior index.

  14. Investigating the vertical dimension of Singapore's urban heat island through quadcopter platforms: an pilot study

    NASA Astrophysics Data System (ADS)

    Chow, Winston; Ho, Dawn

    2016-04-01

    In numerous cities, measurements of urban warmth in most urban heat island (UHI) studies are generally constrained towards surface or near-surface (<2 m above surface level) levels across horizontal variations in land use and land cover. However, there has been hitherto limited attention towards the measurement of vertical temperature profiles extending from the urban surface, urban canopy layer through to the urban boundary layer. Knowledge of these profiles, through (a.) how they vary over different local urban morphologies, and (b.) develop with respect to synoptic meteorological conditions, are important towards several aspects of UHI research; these include validating modelling urban canopy lapse rate profiles or estimating the growth of urban plumes. In this novel study, we utilised temperature sensor-loggers attached onto remote controlled aerial quadcopter platforms to measure urban temperature profiles up to 100 m above ground level in Singapore, which is a rapidly urbanizing major tropical metropolis. Three different land use/land cover categories were sampled; a high-rise residential estate, a university campus, and an urban park/green-space. Sorties were flown repeatedly at four different times - sunrise, noon, sunset and midnight. Initial results indicate significant variations in intra-site stability and inversion development between the urban canopy and boundary layers. These profiles are also temporally dynamic, depending on the time of day and larger-scale weather conditions.

  15. Multiple buoyancy driven flows in a vertical cylinder heated from below

    NASA Technical Reports Server (NTRS)

    Yamaguchi, Y.; Chang, C. J.; Brown, R. A.

    1983-01-01

    The structure of axisymmetric buoyancy-driven convection in a vertical cylinder heated from below is probed by finite element solution of the Boussinesq equations coupled with computed-implemented perturbation techniques for detecting and tracking multiple flows and for determining flow stability. Results are reported for fluids with Prandtl number of one and for cylinders with aspect ratio (Lambda) (defined as the height to radius of the cylinder) between 0.5 and 2.25. Extensive calculations of the neutral stability curve for the static solution and of the nonlinear motions along the bifurcating flow families show a continuous evolution of the primary cellular motion from a single toroidal cell to two and three cells nested radially in the cylinder, instead of the sharp transitions found for a cylinder with shear-free sidewalls. The smooth transitions in flow structure with Rayleigh number and lambda are explained by nonlinear connectivity between the first two bifurcating flow families formed either by a secondary bifurcation point for Lambda or = Lambda * approximately 0.80 or by a limit point for Lambda Lambda *. The transition between these two modes may be described by the theory of multiple limit point bifurcation.

  16. Unsteady convection flow and heat transfer over a vertical stretching surface.

    PubMed

    Cai, Wenli; Su, Ning; Liu, Xiangdong

    2014-01-01

    This paper investigates the effect of thermal radiation on unsteady convection flow and heat transfer over a vertical permeable stretching surface in porous medium, where the effects of temperature dependent viscosity and thermal conductivity are also considered. By using a similarity transformation, the governing time-dependent boundary layer equations for momentum and thermal energy are first transformed into coupled, non-linear ordinary differential equations with variable coefficients. Numerical solutions to these equations subject to appropriate boundary conditions are obtained by the numerical shooting technique with fourth-fifth order Runge-Kutta scheme. Numerical results show that as viscosity variation parameter increases both the absolute value of the surface friction coefficient and the absolute value of the surface temperature gradient increase whereas the temperature decreases slightly. With the increase of viscosity variation parameter, the velocity decreases near the sheet surface but increases far away from the surface of the sheet in the boundary layer. The increase in permeability parameter leads to the decrease in both the temperature and the absolute value of the surface friction coefficient, and the increase in both the velocity and the absolute value of the surface temperature gradient.

  17. Ground-coupled airwaves at Pavlof Volcano, Alaska, and their potential for eruption monitoring

    NASA Astrophysics Data System (ADS)

    Smith, Cassandra M.; McNutt, Stephen R.; Thompson, Glenn

    2016-07-01

    An abnormally high number of explosion quakes were noted during the monitoring effort for the 2007 eruption of Pavlof Volcano on the Alaska Peninsula. In this study, we manually cataloged the explosion quakes from their characteristic ground-coupled airwaves. This study investigates how the ground-coupled airwaves might be used in a monitoring or analysis effort by estimating energy release and gas mass release. Over 3 × 104 quakes were recorded. The energy release from the explosions is approximated to be 3 × 1011 J, and the total gas mass (assuming 100 % water) released was 450 t. The tracking of explosion quakes has the potential to estimate relative eruption intensity as a function of time and is thus a useful component of a seismic monitoring program.

  18. Experimental investigation of convection heat transfer of CO{sub 2} at supercritical pressures in a vertical circular tube

    SciTech Connect

    Li, Zhi-Hui; Jiang, Pei-Xue; Zhao, Chen-Ru; Zhang, Yu.

    2010-11-15

    The convection heat transfer characteristics of supercritical CO{sub 2} in a vertical circular tube of 2 mm inner diameter were investigated experimentally for pressures ranging from 78 to 95 bar, inlet temperatures from 25 to 40 C, and inlet Reynolds numbers from 3800 to 20,000. The effects of the heat flux, thermo-physical properties, buoyancy and thermal acceleration on the convection heat transfer were analyzed. The experimental results show that for high inlet Reynolds numbers (e.g. Re = 9000) and high heat fluxes, a significant local deterioration and recovery of the heat transfer was found for upward flows but not for downward flows. Comparison of the experimental data for inlet Reynolds numbers from 3800 to 20,000 with some well-known empirical correlations showed large differences especially when the heat transfer deteriorates and then recovers when the effect of buoyancy is significant. The experimental data was used to develop modified local turbulent Nusselt number correlations for supercritical CO{sub 2} flowing in vertical small circular tubes. (author)

  19. Circulation, heat exchange and vertical structure of the Hornsund - the Svalbard Archipelago fiord.

    NASA Astrophysics Data System (ADS)

    Jakacki, Jaromir; Przyborska, Anna; Kosecki, Szymon; Sundfjord, Arild

    2015-04-01

    The Hornsund fjord is located in the southwestern part of Spitsbergen- the biggest island of the Svalbard Archipelago. The fjord is influenced by two major currents in this area. The first one is the current carrying the cold and less saline waters around the southern Spitsbergen tip, often called the Sørkapp Current or the South Cape Current. The second is the well-known West Spitsbergen Current (WSC), carrying salty and warm Atlantic Waters through Fram Strait into the Arctic Ocean. From a biological point of view, Hornsund can be treated as a young unstable system or cold system, which suggests that it is under an influence of the South Cape Current. Because of limited measurements in this area, the hydrodynamic model MIKE3D has been implemented for this fjord to diagnose which current has the main influence on Hornsund. The fjord domain was extended into the shelf area. At the lateral boundary of the extended domain, data from the ROMS simulation of the Svalbard area made by the Norwegian Institute of Marine Research (IMR) with resolution of 800 m have been used. Atmospheric data from European Centre for Medium Weather Forecast (ECMWF) were employed as well as from the Global Data Assimilation System (GDAS, 1 and 0.5 degrees) reanalysis that uses metrological data from Polish Polar Station located in Hornsund. Based on 5 years of simulation (2005-2010) seasonal and annual general circulation in the fjord has been described. Estimation of the heat transport between fjord and ocean, and between fjord and atmosphere will permit to establish the heat budget and help to evaluate the influence of the South Cape Current and WSC on the fjord ecosystem development. An influence of the fresh water fluxes and vertical structure of water masses and their transformations will be also discussed. This work was partially performed in the frame of the projects GAME (DEC-2012/04/A/NZ8/00661) and AWAKE2 (Pol-Nor/198675/17/2013)

  20. Numerical modeling of a 2K J-T heat exchanger used in Fermilab Vertical Test Stand VTS-1

    SciTech Connect

    Gupta, Prabhat Kumar; Rabehl, Roger

    2014-07-01

    Fermilab Vertical Test Stand-1 (VTS-1) is in operation since 2007 for testing the superconducting RF cavities at 2 K. This test stand has single layer coiled finned tubes heat exchanger before J-T valve. A finite difference based thermal model has been developed in Engineering Equation Solver (EES) to study its thermal performance during filling and refilling to maintain the constant liquid level of test stand. The model is also useful to predict its performance under other various operating conditions and will be useful to design the similar kind of heat exchanger for future needs. Present paper discusses the different operational modes of this heat exchanger and its thermal characteristics under these operational modes. Results of this model have also been compared with the experimental data gathered from the VTS-1 heat exchanger and they are in good agreement with the present model.

  1. Effects of heat losses (or gains) from insulated portions of closed-loop thermosyphons with vertical heat transfer sections

    NASA Astrophysics Data System (ADS)

    Bernier, M. A.; Baliga, B. R.

    1993-05-01

    The effect of heat losses or gains in the modeling of thermosyphons is investigated analytically using a closed-loop model where the circulating liquid is heated by a constant and uniform heat flux in the heated section of the loop and is cooled in a cooling section maintained at a constant wall temperature; elsewhere the pipes are insulated from the ambient fluid. The results of the analysis indicate that the performance of a closed-loop thermosyphon can be markedly affected by heat gains or losses in the insulated sections of the loop.

  2. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    PubMed

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. PMID:23166688

  3. MHD Free Convective Boundary Layer Flow of a Nanofluid past a Flat Vertical Plate with Newtonian Heating Boundary Condition

    PubMed Central

    Uddin, Mohammed J.; Khan, Waqar A.; Ismail, Ahmed I.

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement. PMID:23166688

  4. MHD free convective boundary layer flow of a nanofluid past a flat vertical plate with Newtonian heating boundary condition.

    PubMed

    Uddin, Mohammed J; Khan, Waqar A; Ismail, Ahmed I

    2012-01-01

    Steady two dimensional MHD laminar free convective boundary layer flows of an electrically conducting Newtonian nanofluid over a solid stationary vertical plate in a quiescent fluid taking into account the Newtonian heating boundary condition is investigated numerically. A magnetic field can be used to control the motion of an electrically conducting fluid in micro/nano scale systems used for transportation of fluid. The transport equations along with the boundary conditions are first converted into dimensionless form and then using linear group of transformations, the similarity governing equations are developed. The transformed equations are solved numerically using the Runge-Kutta-Fehlberg fourth-fifth order method with shooting technique. The effects of different controlling parameters, namely, Lewis number, Prandtl number, buoyancy ratio, thermophoresis, Brownian motion, magnetic field and Newtonian heating on the flow and heat transfer are investigated. The numerical results for the dimensionless axial velocity, temperature and nanoparticle volume fraction as well as the reduced Nusselt and Sherwood number have been presented graphically and discussed. It is found that the rate of heat and mass transfer increase as Newtonian heating parameter increases. The dimensionless velocity and temperature distributions increase with the increase of Newtonian heating parameter. The results of the reduced heat transfer rate is compared for convective heating boundary condition and found an excellent agreement.

  5. High Rayleigh number convection in rectangular enclosures with differentially heated vertical walls and aspect ratios between zero and unity

    NASA Technical Reports Server (NTRS)

    Kassemi, Siavash A.

    1988-01-01

    High Rayleigh number convection in a rectangular cavity with insulated horizontal surfaces and differentially heated vertical walls was analyzed for an arbitrary aspect ratio smaller than or equal to unity. Unlike previous analytical studies, a systematic method of solution based on linearization technique and analytical iteration procedure was developed to obtain approximate closed-form solutions for a wide range of aspect ratios. The predicted velocity and temperature fields are shown to be in excellent agreement with available experimental and numerical data.

  6. Retrieved Vertical Profiles of Latent Heat Release Using TRMM Rainfall Products

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Olson, W. S.; Meneghini, R.; Yang, S.; Simpson, J.; Kummerow, C.; Smith, E.

    2000-01-01

    This paper represents the first attempt to use TRMM rainfall information to estimate the four dimensional latent heating structure over the global tropics for February 1998. The mean latent heating profiles over six oceanic regions (TOGA COARE IFA, Central Pacific, S. Pacific Convergence Zone, East Pacific, Indian Ocean and Atlantic Ocean) and three continental regions (S. America, Central Africa and Australia) are estimated and studied. The heating profiles obtained from the results of diagnostic budget studies over a broad range of geographic locations are used to provide comparisons and indirect validation for the heating algorithm estimated heating profiles. Three different latent heating algorithms, the Goddard Convective-Stratiform (CSH) heating, the Goddard Profiling (GPROF) heating, and the Hydrometeor heating (HH) are used and their results are intercompared. The horizontal distribution or patterns of latent heat release from the three different heating retrieval methods are quite similar. They all can identify the areas of major convective activity (i.e., a well defined ITCZ in the Pacific, a distinct SPCZ) in the global tropics. The magnitude of their estimated latent heating release is also not in bad agreement with each other and with those determined from diagnostic budget studies. However, the major difference among these three heating retrieval algorithms is the altitude of the maximum heating level. The CSH algorithm estimated heating profiles only show one maximum heating level, and the level varies between convective activity from various geographic locations. These features are in good agreement with diagnostic budget studies. By contrast, two maximum heating levels were found using the GPROF heating and HH algorithms. The latent heating profiles estimated from all three methods can not show cooling between active convective events. We also examined the impact of different TMI (Multi-channel Passive Microwave Sensor) and PR (Precipitation Radar

  7. Inverse conjugate mixed convection in a vertical substrate with protruding heat sources: a combined experimental and numerical study

    NASA Astrophysics Data System (ADS)

    Ahamad, Shaik Imran; Balaji, C.

    2016-06-01

    This paper reports the results of a combined numerical and experimental study to estimate the heat inputs of three protruding heat sources of the same size placed on a vertically placed PCB board of height 150 mm, depth 250 mm, and thickness 5 mm. First, limited measurements of temperatures were recorded at eight locations along the height of the back of the PCB board for different (and known) values of heat inputs of the protruding heat sources and different velocities. These were followed by three-dimensional calculations of fluid flow and conjugate heat transfer for various heat transfer coefficients on the backside of the PCB board. The difference between the CFD predicted and experimentally measured temperature distributions on the back of the PCB board was minimized using least squares and the best value of heat transfer coefficient was obtained. Using this `data assimilated' CFD model, detailed CFD simulations were done for various values of heat input values and Reynolds numbers (each of these can be different from one another) of the flow. The temperatures at the same eight locations at the back of the PCB board were noted. An artificial neural network was then developed with ten inputs (eight temperatures together with the input velocity and the ambient temperature) to estimate the three outputs (three heat inputs) after carrying out extensive studies on the architecture of the network. This inverse solution was then tested with experiments for validating the ANN approach to solve the inverse conjugate heat transfer problem. Finally, with the ANN estimated heat inputs, CFD simulations were again run to compare the temperature distribution at the back of the PCB board with measurements.

  8. Measuring the electrical properties of soil using a calibrated ground-coupled GPR system

    USGS Publications Warehouse

    Oden, C.P.; Olhoeft, G.R.; Wright, D.L.; Powers, M.H.

    2008-01-01

    Traditional methods for estimating vadose zone soil properties using ground penetrating radar (GPR) include measuring travel time, fitting diffraction hyperbolae, and other methods exploiting geometry. Additional processing techniques for estimating soil properties are possible with properly calibrated GPR systems. Such calibration using ground-coupled antennas must account for the effects of the shallow soil on the antenna's response, because changing soil properties result in a changing antenna response. A prototype GPR system using ground-coupled antennas was calibrated using laboratory measurements and numerical simulations of the GPR components. Two methods for estimating subsurface properties that utilize the calibrated response were developed. First, a new nonlinear inversion algorithm to estimate shallow soil properties under ground-coupled antennas was evaluated. Tests with synthetic data showed that the inversion algorithm is well behaved across the allowed range of soil properties. A preliminary field test gave encouraging results, with estimated soil property uncertainties (????) of ??1.9 and ??4.4 mS/m for the relative dielectric permittivity and the electrical conductivity, respectively. Next, a deconvolution method for estimating the properties of subsurface reflectors with known shapes (e.g., pipes or planar interfaces) was developed. This method uses scattering matrices to account for the response of subsurface reflectors. The deconvolution method was evaluated for use with noisy data using synthetic data. Results indicate that the deconvolution method requires reflected waves with a signal/noise ratio of about 10:1 or greater. When applied to field data with a signal/noise ratio of 2:1, the method was able to estimate the reflection coefficient and relative permittivity, but the large uncertainty in this estimate precluded inversion for conductivity. ?? Soil Science Society of America.

  9. Identification of type and degree of railway ballast fouling using ground coupled GPR antennas

    NASA Astrophysics Data System (ADS)

    Anbazhagan, P.; Dixit, P. S. Naresh; Bharatha, T. P.

    2016-03-01

    GPR is widely used for ballast fouling identification, however, there are no robust guidelines to find the degree and type of fouling quantitatively. In this study, GPR studies were carried out on model and actual railway tracks using three ground coupled antennas and considering three fouling materials. Three ground coupled antennas viz., 100 MHz, 500 MHz and 800 MHz antennas were used for the initial survey and it was found that the 800 MHz ground coupled antenna is an optimum one to get quality results. Three major fouling materials viz., screened/broken ballast, coal and iron ore were used to construct prototype model sections, which were 1/2 of the actual Indian broad-gauge railway track. A separate model section has been created for each degree and type of fouling and GPR surveys were carried out. GPR study shows that increasing the fouling content results in a decrease in the Electromagnetic Wave (EMW) velocity and an increase in the dielectric constant. EMW velocity of ballast fouled with screened ballast was found to be more than coal fouled ballast and iron ore fouled ballast at any degree of fouling and EMW velocity of iron ore fouled ballast was found to be less than coal and screen ballast fouled ballast. Dielectric constant of iron ore fouled ballast was found to be higher than coal and screen ballast fouled ballast for all degrees of fouling. Average slope of the trend line of screen ballast fouled section is low (25.6°), coal fouled ballast is medium (27.8°) and iron ore fouled ballast is high (47.6°).

  10. Nusselt correlation to predict heat transfer from an oscillated vertical annular fluid column through a porous domain

    NASA Astrophysics Data System (ADS)

    Sayar, Ersin; Sari, Ugurcan

    2016-08-01

    Experimental evaluation of the heat transfer in oscillating flow under the constant heat flux and constant amplitude fluid displacement conditions is presented for a vertical annular flow through a stainless steel wool porous media. The analysis is carried out for two different heat fluxes and for five different frequencies. The data is acquired from the measurements both in the initial transient period and in the pseudo-steady (cyclic) period by the system. The physical and mathematical behavior of the resulting Nusselt numbers are analyzed, according to data acquired from the experiments and in accordance with the results of the Buckingham Pi theorem. A cycle and space averaged Nusselt number correlation is suggested as a function of kinetic Reynolds number for oscillating flows. The suggested correlation is useful in predicting heat transfer from oscillating flows through highly porous and permeable solid media at low actuation frequencies and at low heat fluxes applied in the wall. The validity of the Nusselt numbers acquired by correlation is discussed using experimental Nusselt numbers for the selected kinetic Reynolds number interval. The present investigation has possible applications in moderate sized wicked heat pipes, solid matrix compact heat exchangers compromising of metallic foams, filtration equipment, and steam generators.

  11. Experimental investigation on heat transfer and frictional characteristics of vertical upward rifled tube in supercritical CFB boiler

    SciTech Connect

    Yang, Dong; Pan, Jie; Zhu, Xiaojing; Bi, Qincheng; Chen, Tingkuan; Zhou, Chenn Q.

    2011-02-15

    Water wall design is a key issue for supercritical Circulating Fluidized Bed (CFB) boiler. On account of the good heat transfer performance, rifled tube is applied in the water wall design of a 600 MW supercritical CFB boiler in China. In order to investigate the heat transfer and frictional characteristics of the rifled tube with vertical upward flow, an in-depth experiment was conducted in the range of pressure from 12 to 30 MPa, mass flux from 230 to 1200 kg/(m{sup 2} s), and inner wall heat flux from 130 to 720 kW/m{sup 2}. The wall temperature distribution and pressure drop in the rifled tube were obtained in the experiment. The normal, enhanced and deteriorated heat transfer characteristics were also captured. In this paper, the effects of pressure, inner wall heat flux and mass flux on heat transfer characteristics are analyzed, the heat transfer mechanism and the frictional resistance performance are discussed, and the corresponding empirical correlations are presented. The experimental results show that the rifled tube can effectively prevent the occurrence of departure from nucleate boiling (DNB) and keep the tube wall temperature in a permissible range under the operating condition of supercritical CFB boiler. (author)

  12. Theoretical determination of design parameters for an arrayed heat sink with vertical plate fins

    NASA Astrophysics Data System (ADS)

    Lin, Shiang-Jiun; Chen, Yi-Jin

    2016-05-01

    This paper employs theoretical approach to determine the adequate design parameters of an arrayed plate-fins heat sink based on maximizing heat flow. According to analyzed results, increasing the dimensions of configurative parameters does not always yield the significant increase in the heat flow. As the fin length and fin space increases until a critical value, the heat flow will significantly reduce the increment or decay, respectively.

  13. Diurnal and vertical variability of the sensible heat and carbon dioxide budgets in the atmospheric surface layer

    USGS Publications Warehouse

    Casso-Torralba, P.; de Arellano, J. V. -G.; Bosveld, F.; Soler, M.R.; Vermeulen, A.; Werner, C.; Moors, E.

    2008-01-01

    The diurnal and vertical variability of heat and carbon dioxide (CO2) in the atmospheric surface layer are studied by analyzing measurements from a 213 in tower in Cabauw (Netherlands). Observations of thermodynamic variables and CO2 mixing ratio as well as vertical profiles of the turbulent fluxes are used to retrieve the contribution of the budget terms in the scalar conservation equation. On the basis of the daytime evolution of turbulent fluxes, we calculate the budget terms by assuming that turbulent fluxes follow a linear profile with height. This assumption is carefully tested and the deviation ftom linearity is quantified. The budget calculation allows us to assess the importance of advection of heat and CO2 during day hours for three selected days. It is found that, under nonadvective conditions, the diurnal variability of temperature and CO2 is well reproduced from the flux divergence measurements. Consequently, the vertical transport due to the turbulent flux plays a major role in the daytime evolution of both scalars and the advection is a relatively small contribution. During the analyzed days with a strong contribution of advection of either heat or carbon dioxide, the flux divergence is still an important contribution to the budget. For heat, the quantification of the advection contribution is in close agreement with results from a numerical model. For carbon dioxide, we qualitatively corroborate the results with a Lagrangian transport model. Our estimation of advection is compared with, traditional estimations based on the Net Ecosystem-atmosphere Exchange (NEE). Copyright 2008 by the American Geophysical Union.

  14. Seismic-geodynamic constraints on three-dimensional structure, vertical flow, and heat transfer in the mantle

    USGS Publications Warehouse

    Forte, A.M.; Woodward, R.L.

    1997-01-01

    Joint inversions of seismic and geodynamic data are carried out in which we simultaneously constrain global-scale seismic heterogeneity in the mantle as well as the amplitude of vertical mantle flow across the 670 km seismic discontinuity. These inversions reveal the existence of a family of three-dimensional (3-D) mantle models that satisfy the data while at the same time yielding predictions of layered mantle flow. The new 3-D mantle models we obtain demonstrate that the buoyancy forces due to the undulations of the 670 km phase-change boundary strongly inhibit the vertical flow between the upper and lower mantle. The strong stabilizing effect of the 670 km topography also has an important impact on the predicted dynamic topography of the Earth's solid surface and on the surface gravity anomalies. The new 3-D models that predict strongly or partially layered mantle flow provide essentially identical fits to the global seismic data as previous models that have, until now, predicted only whole-mantle flow. The convective vertical transport of heat across the mantle predicted on the basis of the new 3-D models shows that the heat flow is a minimum at 1000 km depth. This suggests the presence at this depth of a globally defined horizon across which the pattern of lateral heterogeneity changes rapidly. Copyright 1997 by the American Geophysical Union.

  15. Ocean Turbulence. Paper 2; One-Point Closure Model Momentum, Heat and Salt Vertical Diffusivities in the Presence of Shear

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Howard, A.; Cheng, Y.; Dubovikov, M. S.

    1999-01-01

    We develop and test a 1-point closure turbulence model with the following features: 1) we include the salinity field and derive the expression for the vertical turbulent diffusivities of momentum K(sub m) , heat K(sub h) and salt K(sub s) as a function of two stability parameters: the Richardson number R(sub i) (stratification vs. shear) and the Turner number R(sub rho) (salinity gradient vs. temperature gradient). 2) to describe turbulent mixing below the mixed layer (ML), all previous models have adopted three adjustable "background diffusivities" for momentum, heat and salt. We propose a model that avoids such adjustable diffusivities. We assume that below the ML, the three diffusivities have the same functional dependence on R( sub i) and R(sub rho) as derived from the turbulence model. However, in order to compute R(sub i) below the ML, we use data of vertical shear due to wave-breaking.measured by Gargett et al. The procedure frees the model from adjustable background diffusivities and indeed we employ the same model throughout the entire vertical extent of the ocean. 3) in the local model, the turbulent diffusivities K(sub m,h,s) are given as analytical functions of R(sub i) and R(sub rho). 5) the model is used in an O-GCM and several results are presented to exhibit the effect of double diffusion processes. 6) the code is available upon request.

  16. Flow and heat transfer characteristics of laminar mixed convection of water with sub-millimeter bubbles in a vertical channel

    NASA Astrophysics Data System (ADS)

    Kitagawa, A.; Kimura, K.; Endo, H.; Hagiwara, Y.

    2009-02-01

    Laminar mixed-convection heat transfer is widely seen in compact heat exchangers. Injection of sub-millimeter bubbles is considered as one of the efficient techniques for enhancing laminar mixed-convection heat transfer for liquids. However, the effects of sub-millimeter-bubble injection on the laminar mixed-convection heat transfer are poorly understood. In this study, we experimentally investigate flow and heat transfer characteristics of the laminar mixed-convection of water with sub-millimeter bubbles in a vertical channel. The thermocouples and a PTV (Particle Tracking Velocimetry) technique are used for the temperature and velocity measurements, respectively. Tap water is used for working fluid and hydrogen bubbles generated by electrolysis of water are used as the sub-millimeter bubbles. The Reynolds number of the main flow ranges from 100 to 150. Our results show that the ratio of the heat transfer coefficient with sub-millimeter-bubble injection to that without injection decreases as the Reynolds number increases. It is found from the liquid velocity measurements that this decrease is mainly due to a decrease in the "bubble advection effect".

  17. Evaporation heat transfer and friction characteristics of R-134a flowing downward in a vertical corrugated tube

    SciTech Connect

    Aroonrat, Kanit; Wongwises, Somchai

    2011-01-15

    Differently from most previous studies, the heat transfer and friction characteristics of the pure refrigerant HFC-134a during evaporation inside a vertical corrugated tube are experimentally investigated. The double tube test sections are 0.5 m long with refrigerant flowing in the inner tube and heating water flowing in the annulus. The inner tubes are one smooth tube and two corrugated tubes, which are constructed from smooth copper tube of 8.7 mm inner diameter. The test runs are performed at evaporating temperatures of 10, 15, and 20 C, heat fluxes of 20, 25, and 30 kW/m{sup 2}, and mass fluxes of 200, 300, and 400 kg/m{sup 2} s. The quality of the refrigerant in the test section is calculated using the temperature and pressure obtained from the experiment. The pressure drop across the test section is measured directly by a differential pressure transducer. The effects of heat flux, mass flux, and evaporation temperature on the heat transfer coefficient and two-phase friction factor are also discussed. It is found that the percentage increases of the heat transfer coefficient and the two-phase friction factor of the corrugated tubes compared with those of the smooth tube are approximately 0-10% and 70-140%, respectively. (author)

  18. Forced convective flow and heat transfer of upward cocurrent air-water slug flow in vertical plain and swirl tubes

    SciTech Connect

    Chang, Shyy Woei; Yang, Tsun Lirng

    2009-10-15

    This experimental study comparatively examined the two-phase flow structures, pressured drops and heat transfer performances for the cocurrent air-water slug flows in the vertical tubes with and without the spiky twisted tape insert. The two-phase flow structures in the plain and swirl tubes were imaged using the computerized high frame-rate videography with the Taylor bubble velocity measured. Superficial liquid Reynolds number (Re{sub L}) and air-to-water mass flow ratio (AW), which were respectively in the ranges of 4000-10000 and 0.003-0.02 were selected as the controlling parameters to specify the flow condition and derive the heat transfer correlations. Tube-wise averaged void fraction and Taylor bubble velocity were well correlated by the modified drift flux models for both plain and swirl tubes at the slug flow condition. A set of selected data obtained from the plain and swirl tubes was comparatively examined to highlight the impacts of the spiky twisted tape on the air-water interfacial structure and the pressure drop and heat transfer performances. Empirical heat transfer correlations that permitted the evaluation of individual and interdependent Re{sub L} and AW impacts on heat transfer in the developed flow regions of the plain and swirl tubes at the slug flow condition were derived. (author)

  19. Heat transfer in porous medium embedded with vertical plate: Non-equilibrium approach - Part B

    NASA Astrophysics Data System (ADS)

    Quadir, G. A.; Badruddin, Irfan Anjum

    2016-06-01

    This work is continuation of the paper Part A. Due to large number of results, the paper is divided into two section with section-A (Part A) discussing the effect of various parameters such as heat transfer coefficient parameter, thermal conductivity ratio etc. on streamlines and isothermal lines. Section-B highlights the heat transfer characteristics in terms of Nusselt number The Darcy model is employed to simulate the flow inside the medium. It is assumed that the heat transfer takes place by convection and radiation. The governing partial differential equations are converted into non-dimensional form and solved numerically using finite element method.

  20. Influence of wick properties in a vertical LHP on remove waste heat from electronic equipment

    SciTech Connect

    Smitka, Martin E-mail: patrik.nemec@fstroj.uniza.sk Nemec, Patrik E-mail: patrik.nemec@fstroj.uniza.sk Malcho, Milan E-mail: patrik.nemec@fstroj.uniza.sk

    2014-08-06

    The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work is to develop porous wick of sintered nickel powder with different grain sizes. These porous wicks were used in LHP and there were performed a series of measurements to remove waste heat from the insulated gate bipolar transistor (IGBT)

  1. Influence of wick properties in a vertical LHP on remove waste heat from electronic equipment

    NASA Astrophysics Data System (ADS)

    Smitka, Martin; Nemec, Patrik; Malcho, Milan

    2014-08-01

    The loop heat pipe is a vapour-liquid phase-change device that transfers heat from evaporator to condenser. One of the most important parts of the LHP is the porous wick structure. The wick structure provides capillary force to circulate the working fluid. To achieve good thermal performance of LHP, capillary wicks with high permeability and porosity and fine pore radius are expected. The aim of this work is to develop porous wick of sintered nickel powder with different grain sizes. These porous wicks were used in LHP and there were performed a series of measurements to remove waste heat from the insulated gate bipolar transistor (IGBT).

  2. Turbulent combined-convection boundary layer with aiding flows along a heated vertical flat plate at higher freestream velocity

    NASA Astrophysics Data System (ADS)

    Abedina, Mohammad Zoynal; Islam, Mohammed Moinul; Hanif, Md. Abu; Alam, Md. Jahangir

    2016-07-01

    A numerical investigation is performed in the turbulent combined-convection boundary layer with aiding flows in air along a heated vertical flat plate at a higher freestream velocity (Reδ0 = 600) by time-developing direct numerical simulation (DNS). At higher freestream velocity, the transition from laminar to turbulent delays for aiding flows and relatively a lower and higher heat transfer rates are observed, respectively, in the laminar and turbulent region compared to that of lower freestream velocity. The wall shear stresses are higher in the laminar region compared to that in the turbulent region, and at higher freestream velocity, the wall shear stress in the transition region shows a higher peak value. The intensity of velocity and temperature fluctuations for aiding flows with higher freestream velocity become appreciably lower than that for lower freestream velocity due to the laminarization of the boundary layer.

  3. Vertical Mass, Momentum, Moisture, and Heat Fluxes in Hurricanes above 10 km during CAMEX-3 and CAMEX-4

    NASA Technical Reports Server (NTRS)

    Pfister, Leonhard; Bui, Paul; Herman, Robert; Dean-Day, Jon; Hipskind, R. Stephen (Technical Monitor)

    2002-01-01

    The third and fourth NASA Convection and Moisture Experiments (CAMEX-3 and CAMEX-4) during the Atlantic hurricane seasons of 1998 and 2001, respectively, have yielded comprehensive multi-aircraft datasets using, both remote and in-situ instrumentation. Among these are high-frequency in-situ measurements of vertical wind, horizontal wind, temperature, and water vapor, made from NASA's DC-8 aircraft in the upper portions of the hurricane (typically above 10 km). Wind and temperature measurements were made at 20 hz by the NASA/Ames Meteorological Measurement System, while water vapor was measured at 1 hz by the NASA/JPL Laser Hygrometer. Fluxes of heat, momentum, and moisture at these levels are important, since modeling studies have shown that ice processes, which are dominant at temperatures below -40C (where the DC-8 flies) are important for hurricane intensification. Also, there are indications from satellite studies that latent heat release at DC-8 levels is significant, perhaps a third of those in the mid-troposphere. Preliminary results show that typical updrafts in the eyewall region are comparable to or higher than previous observations of tropical convection, with several instances of updraft magnitudes of 15 meters per second (the maximum observed was 21 meters per second). They also show significant supersaturations (10-20% or more) in the updrafts, which would enhance the latent heat release at the upper levels of the hurricane. This paper will examine the magnitude and distribution of small and mesoscale vertical fluxes of mass, momentum, moisture, and heat. The goal is to examine the role of these fluxes in the overall budgets of the respective quantities in the upper portions of the hurricane.

  4. Ground-coupled air waves and diffracted infrasound from the Arequipa earthquake of June 23, 2001

    NASA Astrophysics Data System (ADS)

    Le Pichon, A.; Guilbert, J.; Vega, A.; Garcés, M.; Brachet, N.

    2002-09-01

    On June 23, 2001, a strong earthquake measuring Mw 8.4 occurred along the coast of south-central Peru. Coherent infrasonic waves were detected over a period of one hour by the IS08 infrasound station in Bolivia. Analysis of the ground-coupled air waves shows that the rupture propagated from the northwestern to the southeastern part of the fault with a rupture velocity of 3.3 km/s. The azimuth variation of the infrasonic waves is attributed to a distribution of secondary sources along the highest mountain ranges, which excite infrasonic waves that are diffracted to the ground. The predominant source of infrasound is likely distributed along the Andean Cordillera. Using the azimuth and arrival time determination, the horizontal scale size of the distant source regions of infrasonic waves is reconstructed over distances greater than 400 km.

  5. Geothermal studies of the Outokumpu Deep Drill Hole, Finland: Vertical variation in heat flow and palaeoclimatic implications

    NASA Astrophysics Data System (ADS)

    Kukkonen, Ilmo T.; Rath, Volker; Kivekäs, Liisa; Šafanda, Jan; Čermak, Vladimir

    2011-09-01

    Detailed geothermal studies of deep drill holes provide insights to heat transfer processes in the crust, and allow separation of different factors involved, such as palaeoclimatic and structural conductive effects as well as advective fluid flow effects. We present high resolution geothermal results of the 2516 m deep Outokumpu Deep Drill Hole in eastern Finland drilled in 2004-2005 into a Palaeoproterozoic formation with metasedimentary rocks, ophiolite-derived altered ultramafic rocks and pegmatitic granite. The down-hole temperatures have been logged five times after end of drilling and extend to day 948 after drilling. The hole is completely cored (79% core coverage) and thermal conductivity measurements were done at 1 m intervals. The geothermal results on temperature gradient, thermal conductivity and heat flow density yield an exceptionally detailed data set and indicate a significant vertical variation in gradient and heat flow density. Heat flow density increases from about 28 - 32 mW m -2 in the uppermost 1000 m to 40-45 mW m -2 at depths exceeding 2000 m. The estimated undisturbed surface heat flow value is 42 mW m -2. We present results on forward and inverse transient conductive models which suggest that the vertical variation in heat flow can mostly be attributed to a palaeoclimatic effect due to ground surface temperature (GST) variations during the last 100,000 years. The modeling suggests that the average GST was about -3 to -4 °C during the Weichselian glaciation. Holocene GST values are within ±2° from the present average GST in Outokumpu (5 °C). The topographic hydraulic heads and hydraulic conductivity of crystalline rocks are low which suggests that advective heat transfer in the formation is not significant. The slow replacement of fresh flushing water by saline formation fluids is observed in the hole, but it does not generate significant thermal disturbances in the logs. On the other hand, free sluggish thermal convection is present in

  6. Geothermal Studies of the Outokumpu Deep Drill Hole, Finland: Vertical variation in heat flow and palaeoclimatic implications

    NASA Astrophysics Data System (ADS)

    Kukkonen, I. T.; Rath, V.; Kivekäs, L.; Šafanda, J.; Čermak, V.

    2012-04-01

    Detailed geothermal studies of deep drill holes provide insights to heat transfer processes in the crust, and allow separation of different factors involved, such as palaeoclimatic and structural conductive effects as well as advective fluid flow effects. We present high resolution geothermal results of the 2,516 m deep Outokumpu Deep Drill Hole in eastern Finland drilled in 2004-2005 into a Palaeoproterozoic formation with metasedimentary rocks, ophiolite-derived altered ultramafic rocks and pegmatitic granite. The down-hole temperatures have been logged five times after end of drilling and extend to day 948 after drilling. The hole is completely cored (79% core coverage) and thermal conductivity measurements were done at 1 m intervals. The geothermal results on temperature gradient, thermal conductivity and heat flow density yield an exceptionally detailed data set and indicate a significant vertical variation in gradient and heat flow density. Heat flow density increases from about 28-32 mW m-2 in the uppermost 1000 m to 40-45 mW m-2 at depths exceeding 2000 m. The estimated undisturbed surface heat flow value is 42 mWm-2. We present results on forward and inverse transient conductive models which suggest that the vertical variation in heat flow can mostly be attributed to a palaeoclimatic effect due to ground surface temperature (GST) variations during the last 100,000 years. The modelling suggests that the average GST was about -3…-4°C during the Weichselian glaciation. Holocene GST values are within ±2 degree from the present average GST in Outokumpu (5°C). The topographic hydraulic heads and hydraulic conductivity of crystalline rocks are low which suggests that advective heat transfer in the formation is not significant. The slow replacement of fresh flushing water by saline formation fluids is observed in the hole, but it does not generate significant thermal disturbances in the logs. On the other hand, free sluggish thermal convection is present in

  7. MHD forced convective laminar boundary layer flow from a convectively heated moving vertical plate with radiation and transpiration effect.

    PubMed

    Uddin, Md Jashim; Khan, Waqar A; Ismail, A I Md

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to x(m) whilst the magnetic field and mass transfer velocity are taken to be proportional to x((m-1)/2) where x is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory. PMID:23741295

  8. MHD forced convective laminar boundary layer flow from a convectively heated moving vertical plate with radiation and transpiration effect.

    PubMed

    Uddin, Md Jashim; Khan, Waqar A; Ismail, A I Md

    2013-01-01

    A two-dimensional steady forced convective flow of a Newtonian fluid past a convectively heated permeable vertically moving plate in the presence of a variable magnetic field and radiation effect has been investigated numerically. The plate moves either in assisting or opposing direction to the free stream. The plate and free stream velocities are considered to be proportional to x(m) whilst the magnetic field and mass transfer velocity are taken to be proportional to x((m-1)/2) where x is the distance along the plate from the leading edge of the plate. Instead of using existing similarity transformations, we use a linear group of transformations to transform the governing equations into similarity equations with relevant boundary conditions. Numerical solutions of the similarity equations are presented to show the effects of the controlling parameters on the dimensionless velocity, temperature and concentration profiles as well as on the friction factor, rate of heat and mass transfer. It is found that the rate of heat transfer elevates with the mass transfer velocity, convective heat transfer, Prandtl number, velocity ratio and the magnetic field parameters. It is also found that the rate of mass transfer enhances with the mass transfer velocity, velocity ratio, power law index and the Schmidt number, whilst it suppresses with the magnetic field parameter. Our results are compared with the results existing in the open literature. The comparisons are satisfactory.

  9. Natural convection in an enclosure with discrete roughness elements on a vertical heated wall

    SciTech Connect

    Shakerin, S; Bohn, M S; Loehrke, R I

    1986-02-01

    Natural convection flow next to a heated wall with single and repeated, two-dimensional, rectangular roughness elements is studied numerically and experimentally. The objective is to determine how these roughness elements influence heat transfer rates from the wall. Each roughness element consists of a thermally conducting, horizontal cylinder of rectangular cross section attached to the heated, isothermal wall of an enclosure. The height of roughness is on the order of the boundary layer thickness. Dye flow visualization in water confirms the numerical prediction that the steady flow over these elements does not separate. Only at high Rayleigh numbers, when the boundary layer below the roughness is unsteady, is local instantaneous flow reversal observed. Although steady flow reversals near the wall are not predicted or observed, nearly stagnant regions are formed, particularly between closely spaced cylinders. The surface heat flux in these stagnant regions is relatively low, so the total heat transfer rate may be nearly the same as for a smooth wall in spite of the increased surface area.

  10. Impact of aerosol vertical distribution on aerosol direct radiative effect and heating rate in the Mediterranean region

    NASA Astrophysics Data System (ADS)

    Pappas, Vasileios; Hatzianastassiou, Nikolaos; Matsoukas, Christos; Koras Carracca, Mario; Kinne, Stefan; Vardavas, Ilias

    2015-04-01

    It is now well-established that aerosols cause an overall cooling effect at the surface and a warming effect within the atmosphere. At the top of the atmosphere (TOA), both positive and negative forcing can be found, depending on a number of other factors, such as surface albedo and relative position of clouds and aerosols. Whilst aerosol surface cooling is important due to its relation with surface temperature and other bio-environmental reasons, atmospheric heating is of special interest as well having significant impacts on atmospheric dynamics, such as formation of clouds and subsequent precipitation. The actual position of aerosols and their altitude relative to clouds is of major importance as certain types of aerosol, such as black carbon (BC) above clouds can have a significant impact on planetary albedo. The vertical distribution of aerosols and clouds has recently drawn the attention of the aerosol community, because partially can account for the differences between simulated aerosol radiative forcing with various models, and therefore decrease the level of our uncertainty regarding aerosol forcing, which is one of our priorities set by IPCC. The vertical profiles of aerosol optical and physical properties have been studied by various research groups around the world, following different methodologies and using various indices in order to present the impact of aerosols on radiation on different altitudes above the surface. However, there is still variability between the published results as to the actual effect of aerosols on shortwave radiation and on heating rate within the atmosphere. This study uses vertical information on aerosols from the Max Planck Aerosol Climatology (MAC-v1) global dataset, which is a combination of model output with quality ground-based measurements, in order to provide useful insight into the vertical profile of atmospheric heating for the Mediterranean region. MAC-v1 and the science behind this aerosol dataset have already

  11. Characteristics, vertical structures and heat/salt transports of mesoscale eddies in the southeastern tropical Indian Ocean

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Yu, Weidong; Zhao, Xia; Wang, Fan; Liu, Lin

    2016-04-01

    Satellite altimetry sea surface height measurements reveal high mesoscale eddy activity in the southeastern tropical Indian Ocean (SETIO). In this study, the characteristics of mesoscale eddies in the SETIO are investigated by analyzing 564 cyclonic eddy (CE) tracks and 695 anticyclonic eddy (AE) tracks identified from a new version of satellite altimetry data with a daily temporal resolution. The mean radius, lifespan, propagation speed and distance of CEs (AEs) are 149 (153) km, 50 (46) days, 15.3 (16.6) cm s-1, and 651 (648) km, respectively. Some significant differences exist in the eddy statistical characteristics between the new-version daily altimeter data and the former weekly data. Mean vertical structures of anomalous potential temperature, salinity, geostrophic current, as well as heat and salt transports of the composite eddies, are estimated by analyzing Argo profile data matched to altimeter-detected eddies. The composite analysis shows that eddy-induced ocean anomalies are mainly confined in the upper 300 dbar. In the eddy core, CE (AE) could induce a cooling (warming) of 2°C between 60 and 180 dbar and maximum positive (negative) salinity anomalies of 0.1 (-0.3) psu in the upper 50 (110) dbar. The meridional heat transport induced by the composite CE (AE) is southward (northward), whereas the salt transport of CE (AE) is northward (southward). Most of the meridional heat and salt transports are carried in the upper 300 dbar.

  12. The empirical correlations for natural convection heat transfer Al2O3 and ZrO2 nanofluid in vertical sub-channel

    NASA Astrophysics Data System (ADS)

    Kamajaya, K.; Umar, E.; Sudjatmi

    2015-09-01

    Study on convection heat transfer using water-Al2O3 nanofluid as the working fluid in the vertical sub-channel has been conducted. The results of the study have been compared with the water-ZrO2 nanofluid and pure-water as the working fluid. The equipment used in this experiment is a vertical triangular sub-channel, equipped by primary cooling system, heat exchanger and a secondary cooling system. As a heating source used three vertical cylinders that have a uniform heat flux with a pitch to diameter ratio (P/D) 01:16. Cooling is used is water-Al2O3 colloid at 0.05 wt. %. Heat transfer from heating to cooling would occur in natural or forced convection. However, in this study will be discussed only natural convection heat transfer. The results showed that the natural convection heat transfer of water-Al2O3 nanofluid in a triangular sub-channels depending on the position. The results of the correlation as follows,

  13. Natural convection flow of Cu-H2O nanofluid along a vertical wavy surface with uniform heat flux

    NASA Astrophysics Data System (ADS)

    Habiba, Farjana; Molla, Md. Mamun; Khan, M. A. Hakim

    2016-07-01

    A numerical study on natural convection flow of Cu-Water nanofluid along a vertical wavy surface with uniform heat flux has been carried out. The governing boundary layer equations are transformed into parabolic partial differential equations by applying a suitable set of variables. The resulting nonlinear system of equations are then mapped into a regular rectangular computational domain and solved numerically by using an implicit finite difference method. Numerical results are thoroughly discussed in terms of velocity and temperature distributions, surface temperature distribution, skin friction coefficient and Nusselt number coefficient for selected key parameters such as solid volume fraction of nanofluid (ϕ) and amplitude (α) of surface waviness. In addition, velocity vectors, streamlines and isotherms are plotted to visualize momentum and thermal flow pattern within the boundary layer region.

  14. Study of dynamic structure and heat and mass transfer of a vertical ceramic tiles dryer using CFD simulations

    NASA Astrophysics Data System (ADS)

    Kriaa, Wassim; Bejaoui, Salma; Mhiri, Hatem; Le Palec, Georges; Bournot, Philippe

    2014-02-01

    In this study, we developed a two-dimensional Computational Fluid Dynamics (CFD) model to simulate dynamic structure and heat and mass transfer of a vertical ceramic tiles dryer (EVA 702). The carrier's motion imposed the choice of a dynamic mesh based on two methods: "spring based smoothing" and "local remeshing". The dryer airflow is considered as turbulent ( Re = 1.09 × 105 at the dryer inlet), therefore the Re-Normalization Group model with Enhanced Wall Treatment was used as a turbulence model. The resolution of the governing equation was performed with Fluent 6.3 whose capacities do not allow the direct resolution of drying problems. Thus, a user defined scalar equation was inserted in the CFD code to model moisture content diffusion into tiles. User-defined functions were implemented to define carriers' motion, thermo-physical properties… etc. We adopted also a "two-step" simulation method: in the first step, we follow the heat transfer coefficient evolution (Hc). In the second step, we determine the mass transfer coefficient (Hm) and the features fields of drying air and ceramic tiles. The found results in mixed convection mode (Fr = 5.39 at the dryer inlet) were used to describe dynamic and thermal fields of airflow and heat and mass transfer close to the ceramic tiles. The response of ceramic tiles to heat and mass transfer was studied based on Biot numbers. The evolutions of averages temperature and moisture content of ceramic tiles were analyzed. Lastly, comparison between experimental and numerical results showed a good agreement.

  15. Detecting hidden volcanic explosions from Mt. Cleveland Volcano, Alaska with infrasound and ground-couples airwaves

    USGS Publications Warehouse

    De Angelis, Slivio; Fee, David; Haney, Matthew; Schneider, David

    2012-01-01

    In Alaska, where many active volcanoes exist without ground-based instrumentation, the use of techniques suitable for distant monitoring is pivotal. In this study we report regional-scale seismic and infrasound observations of volcanic activity at Mt. Cleveland between December 2011 and August 2012. During this period, twenty explosions were detected by infrasound sensors as far away as 1827 km from the active vent, and ground-coupled acoustic waves were recorded at seismic stations across the Aleutian Arc. Several events resulting from the explosive disruption of small lava domes within the summit crater were confirmed by analysis of satellite remote sensing data. However, many explosions eluded initial, automated, analyses of satellite data due to poor weather conditions. Infrasound and seismic monitoring provided effective means for detecting these hidden events. We present results from the implementation of automatic infrasound and seismo-acoustic eruption detection algorithms, and review the challenges of real-time volcano monitoring operations in remote regions. We also model acoustic propagation in the Northern Pacific, showing how tropospheric ducting effects allow infrasound to travel long distances across the Aleutian Arc. The successful results of our investigation provide motivation for expanded efforts in infrasound monitoring across the Aleutians and contributes to our knowledge of the number and style of vulcanian eruptions at Mt. Cleveland.

  16. Pavement thickness and stabilised foundation layer assessment using ground-coupled GPR

    NASA Astrophysics Data System (ADS)

    Hu, Jinhui; Vennapusa, Pavana K. R.; White, David J.; Beresnev, Igor

    2016-07-01

    Experimental results from field and laboratory investigations using a ground-coupled ground penetrating radar (GPR), dielectric measurement, magnetic imaging tomography (MIT) and dynamic cone penetrometer (DCP) tests are presented. Dielectric properties of asphalt pavement and stabilised and unstabilised pavement foundation materials were evaluated in the laboratory in frozen and unfrozen conditions. Laboratory test results showed that dielectric properties of materials back-calculated from GPR in comparison to dielectric gauge measurements are strongly correlated and repeatable. For chemically stabilised materials, curing time affected the dielectric properties of the materials. Field tests were conducted on asphalt pavement test sections with different foundation materials (stabilised and unstabilised layers), drainage conditions and layer thicknesses. GPR and MIT results were used to determine asphalt layer thicknesses and were compared with measured core thicknesses, while GPR and DCP were used to assess foundation layer profiles. Asphalt thicknesses estimated from GPR showed an average error of about 11% using the dielectric gauge values as input. The average error reduced to about 4% when calibrated with cores thicknesses. MIT results showed thicknesses that are about 9% higher than estimated using GPR. Foundation layer thicknesses could not be measured using GPR due to variations in moisture conditions between the test sections, which is partly attributed to variations in gradation and drainage characteristics of the subbase layer.

  17. Effects of vertically ribbed surface roughness on the forced convective heat losses in central receiver systems

    NASA Astrophysics Data System (ADS)

    Uhlig, Ralf; Frantz, Cathy; Fritsch, Andreas

    2016-05-01

    External receiver configurations are directly exposed to ambient wind. Therefore, a precise determination of the convective losses is a key factor in the prediction and evaluation of the efficiency of the solar absorbers. Based on several studies, the forced convective losses of external receivers are modeled using correlations for a roughened cylinder in a cross-flow of air. However at high wind velocities, the thermal efficiency measured during the Solar Two experiment was considerably lower than the efficiency predicted by these correlations. A detailed review of the available literature on the convective losses of external receivers has been made. Three CFD models of different level of detail have been developed to analyze the influence of the actual shape of the receiver and tower configuration, of the receiver shape and of the absorber panels on the forced convective heat transfer coefficients. The heat transfer coefficients deduced from the correlations have been compared to the results of the CFD simulations. In a final step the influence of both modeling approaches on the thermal efficiency of an external tubular receiver has been studied in a thermal FE model of the Solar Two receiver.

  18. Ocean Turbulence. Paper 3; Two-Point Closure Model Momentum, Heat and Salt Vertical Diffusivities in the Presence of Shear

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Dubovikov, M. S.; Howard, A.; Cheng, Y.

    1999-01-01

    In papers 1 and 2 we have presented the results of the most updated 1-point closure model for the turbulent vertical diffusivities of momentum, heat and salt, K(sub m,h,s). In this paper, we derive the analytic expressions for K(sub m,h,s) using a new 2-point closure model that has recently been developed and successfully tested against some approx. 80 turbulence statistics for different flows. The new model has no free parameters. The expressions for K(sub m, h. s) are analytical functions of two stability parameters: the Turner number R(sub rho) (salinity gradient/temperature gradient) and the Richardson number R(sub i) (temperature gradient/shear). The turbulent kinetic energy K and its rate of dissipation may be taken local or non-local (K-epsilon model). Contrary to all previous models that to describe turbulent mixing below the mixed layer (ML) have adopted three adjustable "background diffusivities" for momentum. heat and salt, we propose a model that avoids such adjustable diffusivities. We assume that below the ML, K(sub m,h,s) have the same functional dependence on R(sub i) and R(sub rho) derived from the turbulence model. However, in order to compute R(sub i) below the ML, we use data of vertical shear due to wave-breaking measured by Gargett et al. (1981). The procedure frees the model from adjustable background diffusivities and indeed we use the same model throughout the entire vertical extent of the ocean. Using the new K(sub m,h, s), we run an O-GCM and present a variety of results that we compare with Levitus and the KPP model. Since the traditional 1-point (used in papers 1 and 2) and the new 2-point closure models used here represent different modeling philosophies and procedures, testing them in an O-GCM is indispensable. The basic motivation is to show that the new 2-point closure model gives results that are overall superior to the 1-point closure in spite of the fact that the latter rely on several adjustable parameters while the new 2-point

  19. A Study on a Performance of Water-Spray-Type Ice Thermal Energy Storage Vessel with Vertical Heat Exchanger Plates

    NASA Astrophysics Data System (ADS)

    Yoshimura, Kenji; Sasaguchi, Kengo; Fukuda, Toshihito; Koyama, Shigeru

    A system with a water-embedded-trpe ice storage vessel is widely used because of its simple structure and compactness. However, the water-embedded-type ice storage vessel has a disadvantage, that is, the solidification rate is very small. The use of falling water film seems to be one of promising ways for solving this disadvantage. We have found in a previous study that the use of the falling water film is very effective, especially for high initial water temperatures. In the present study, we eexamined the performance of a faling-water-film-type ice thermal energy storage vessel with pratical size, having vertical heat exchanger plates. The ice making performance coefficient, η, increases with time, and it becomes am aximum value of 2.5, after that, it decreases gradually. In order to make ice efficiently, it is necessary to set a flow rate of refrigerant properly and to adjust a difference between the evaporating temperature of refrigerant and the freezing point of water so that the refrigerant evaporates in the heat exchanger plates overall.

  20. MEASURED SPACE CONDITIONING PERFORMANCE OFA VERTICAL-BORE GROUND SOURCE HEAT PUMP (GSHP) OVER TWELVE MONTHS UNDER SIMULATED OCCUPANCY LOADS

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2014-01-01

    This paper presents monthly performance metrics of a 7.56 kW (2.16 ton) GSHP serving the space conditioning loads of a 251m2 (2700ft2) residential home with a phase change material in its envelope, and a single vertical-bore 94.5m (310 ft) ground loop. The same ground loop also serviced a ground source heat pump water heater. Envelope characteristics are discussed briefly in the context of reducing thermal losses. Data on entering water temperatures, energy extracted from the ground, energy delivered/removed, compressor electricity use, COP, GSHP run times (low and high compressor stages), and the impact of fan and pump energy consumption on efficiency are presented for each month. Both practical as well as research and development issues are discussed. The findings suggest that GSHPs represent a practical technology option to reduce source energy reduction and greenhouse emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 target of generating over 25% of heat consumed in the EU from renewable energy.

  1. Particle image velocimetry measurements for opposing flow in a vertical channel with a differential and asymmetric heating condition

    SciTech Connect

    Martinez-Suastegui, L.; Trevino, C.

    2007-10-15

    Particle image velocimetry (PIV) measurements were carried out in an experimental investigation of laminar mixed convection in a vertical duct with a square cross-section. The main downward water-flow is driven by gravity while a portion of a lateral side is heated, and buoyancy forces produce non-stationary vortex structures close to the heated region. Various ranges of the Grashof number, Gr are studied in combination with the Reynolds number, Re varying from 300 to 700. The values of the generalized buoyancy parameter or Richardson number, Ri = Gr/Re{sup 2} parallel to the Grashof number are included in the results. The influence of these nondimensional parameters and how they affect the fluid flow structure and vortex sizes and locations are reported. The flow patterns are nonsymmetric, periodic, and exhibit increasing complexity and frequency for increasing buoyancy. For the averaged values of the resulting vortex dimensions, it was found that a better and more congruent representation occurs when employing the Grashof and Reynolds numbers as independent parameters. (author)

  2. Data, exergy, and energy analysis of a vertical-bore, ground-source heat pump to for domestic water heating under simulated occupancy conditions

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D.; Baxter, Van D.; Gehl, Anthony C.

    2015-05-27

    Evidence is provided to support the view that greater than two-thirds of energy required to produce domestic hot water may be extracted from the ground which serves as renewable energy resource. The case refers to a 345 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days (3993 F-days) and CDD of 723 C-days (1301 F-days). The house is operated under simulated occupancy conditions in which the hot water use protocol is based on the Building America Research Benchmark Definition (Hendron 2008; Hendron and Engebrecht 2010) which captures the water consumption lifestyles of the average family in the United States. The 5.275 (1.5-ton) water-to-water ground source heat pump (WW-GSHP) shared the same vertical bore with a 7.56 KW water-to-air ground source heat pump for space conditioning the same house. Energy and exergy analysis of data collected continuously over a twelve month period provide performance metrics and sources of inherent systemic inefficiencies. Data and analyses are vital to better understand how WW-GSHPs may be further improved to enable the ground to be used as a renewable energy resource.

  3. Data, exergy, and energy analysis of a vertical-bore, ground-source heat pump to for domestic water heating under simulated occupancy conditions

    DOE PAGESBeta

    Ally, Moonis Raza; Munk, Jeffrey D.; Baxter, Van D.; Gehl, Anthony C.

    2015-05-27

    Evidence is provided to support the view that greater than two-thirds of energy required to produce domestic hot water may be extracted from the ground which serves as renewable energy resource. The case refers to a 345 m2 research house located in Oak Ridge, Tennessee, 36.01 N 84.26 W in a mixed-humid climate with HDD of 2218 C-days (3993 F-days) and CDD of 723 C-days (1301 F-days). The house is operated under simulated occupancy conditions in which the hot water use protocol is based on the Building America Research Benchmark Definition (Hendron 2008; Hendron and Engebrecht 2010) which captures themore » water consumption lifestyles of the average family in the United States. The 5.275 (1.5-ton) water-to-water ground source heat pump (WW-GSHP) shared the same vertical bore with a 7.56 KW water-to-air ground source heat pump for space conditioning the same house. Energy and exergy analysis of data collected continuously over a twelve month period provide performance metrics and sources of inherent systemic inefficiencies. Data and analyses are vital to better understand how WW-GSHPs may be further improved to enable the ground to be used as a renewable energy resource.« less

  4. The Correlation of Coupled Heat and Mass Transfer Experimental Data for Vertical Falling Film Absorption

    SciTech Connect

    Keyhani, M; Miller, W A

    1999-11-14

    Absorption chillers are gaining global acceptance as quality comfort cooling systems. These machines are the central chilling plants and the supply for cotnfort cooling for many large commercial buildings. Virtually all absorption chillers use lithium bromide (LiBr) and water as the absorption fluids. Water is the refrigerant. Research has shown LiBr to he one of the best absorption working fluids because it has a high affinity for water, releases water vapor at relatively low temperatures, and has a boiling point much higher than that of water. The heart of the chiller is the absorber, where a process of simultaneous heat and mass transfer occurs as the refrigerant water vapor is absorbed into a falling film of aqueous LiBr. The more water vapor absorbed into the falling film, the larger the chiller's capacity for supporting comfort cooling. Improving the performance of the absorber leads directly to efficiency gains for the chiller. The design of an absorber is very empirical and requires experimental data. Yet design data and correlations are sparse in the open literature. The experimental data available to date have been derived at LiBr concentrations ranging from 0.30 to 0.60 mass fraction. No literature data are readily available for the design operating conditions of 0.62 and 0.64 mass fraction of LiBr and absorber pressures of 0.7 and 1.0 kPa.

  5. Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

    NASA Astrophysics Data System (ADS)

    Kurylyk, Barret L.; Hayashi, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

    2016-02-01

    Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

  6. Influence of vertical and lateral heat transfer on permafrost thaw, peatland landscape transition, and groundwater flow

    USGS Publications Warehouse

    Kurylyk, Barret; Masaki, Masaki; Quinton, William L.; McKenzie, Jeffrey M.; Voss, Clifford I.

    2016-01-01

    Recent climate change has reduced the spatial extent and thickness of permafrost in many discontinuous permafrost regions. Rapid permafrost thaw is producing distinct landscape changes in the Taiga Plains of the Northwest Territories, Canada. As permafrost bodies underlying forested peat plateaus shrink, the landscape slowly transitions into unforested wetlands. The expansion of wetlands has enhanced the hydrologic connectivity of many watersheds via new surface and near-surface flow paths, and increased streamflow has been observed. Furthermore, the decrease in forested peat plateaus results in a net loss of boreal forest and associated ecosystems. This study investigates fundamental processes that contribute to permafrost thaw by comparing observed and simulated thaw development and landscape transition of a peat plateau-wetland complex in the Northwest Territories, Canada from 1970 to 2012. Measured climate data are first used to drive surface energy balance simulations for the wetland and peat plateau. Near-surface soil temperatures simulated in the surface energy balance model are then applied as the upper boundary condition to a three-dimensional model of subsurface water flow and coupled energy transport with freeze-thaw. Simulation results demonstrate that lateral heat transfer, which is not considered in many permafrost models, can influence permafrost thaw rates. Furthermore, the simulations indicate that landscape evolution arising from permafrost thaw acts as a positive feedback mechanism that increases the energy absorbed at the land surface and produces additional permafrost thaw. The modeling results also demonstrate that flow rates in local groundwater flow systems may be enhanced by the degradation of isolated permafrost bodies.

  7. Effect of Smoke and Moisture on Vertical Heating Rate of Southeast Atlantic

    NASA Astrophysics Data System (ADS)

    Adebiyi, A.; Zuidema, P.

    2012-12-01

    Seasonal biomass burning in the southwestern Africa Savannah produces a layer of dark smoke over the southeast Atlantic Ocean(SEA) with the peak typically occurring during August and September(AS). This absorbing layer, distinctively separated from the underlying stratocumulus deck, has been shown to preserve humidity and cloud cover in the boundary layer by enhancing the buoyancy of the free-tropospheric air above the inversion layer thereby inhibiting the entrainment of dry air through the cloud top. Using the observations from St. Helena Island(15.93S/5.67W) as a representation of SEA, we binned the Integrated Global Radiosonde Archive's(IGRA) soundings for AS by the fine-mode aerosol optical depth(AOD) for smoke using the Moderate Resolution Imaging Spectroradiometer(MODIS). It was noted that higher AOD is associated with relatively positive moisture and cooler temperature anomaly below the boundary layer. We also examine the relative impact of smoke and moisture at the same location by preforming a number experiments using the Santa Barbara DISORT Atmospheric Radiative Transfer model constrained by the averaged sounding and observations from MODIS and CALIPSO satellite products for AS. It was found that for every 0.1 increase in AOD, the average heating rate within the smoke layer increases by approximately 0.83K/day, if there is an underlying cloud due to the reflection of the cloud in shortwave and 0.56K/day, if there is no underlying cloud. The result will aid regional and climate model evaluations of black carbon indirect effect for southeast Atlantic.

  8. Characterizing fractured rock aquifers using heated Distributed Fiber-Optic Temperature Sensing to determine borehole vertical flow

    NASA Astrophysics Data System (ADS)

    Read, T. O.; Bour, O.; Selker, J. S.; Le Borgne, T.; Bense, V.; Hochreutener, R.; Lavenant, N.

    2013-12-01

    In highly heterogeneous media, fracture network connectivity and hydraulic properties can be estimated using methods such as packer- or cross-borehole pumping-tests. Typically, measurements of hydraulic head or vertical flow in such tests are made either at a single location over time, or at a series of depths by installing a number of packers or raising or lowering a probe. We show how this often encountered monitoring problem, with current solutions sacrificing either one of temporal or spatial information, can be addressed using Distributed Temperature Sensing (DTS). Here, we electrically heat the conductive cladding materials of cables deployed in boreholes to determine the vertical flow profile. We present results from heated fiber optic cables deployed in three boreholes in a fractured rock aquifer at the much studied experimental site near Ploemeur, France, allowing detailed comparisons with alternative methods (e.g. Le Borgne et al., 2007). When submerged in water and electrically heated, the cable very rapidly reaches a steady state temperature (less than 60 seconds). The steady state temperature of the heated cable, measured using the DTS method, is then a function of the velocity of the fluid in the borehole. We find that such cables are sensitive to a wide range of fluid velocities, and thus suitable for measuring both ambient and pumped flow profiles at the Ploemeur site. The cables are then used to monitor the flow profiles during all possible configurations of: ambient flow, cross-borehole- (pumping one borehole, and observing in another), and dipole-tests (pumping one borehole, re-injection in another). Such flow data acquired using DTS may then be used for tomographic flow inversions, for instance using the approach developed by Klepikova et al., (submitted). Using the heated fiber optic method, we are able to observe the flow response during such tests in high spatial detail, and are also able to capture temporal flow dynamics occurring at the

  9. Experimental study of the Marangoni flow in evaporating water droplet placed on vertical vibration and heated hydrophobic surface

    NASA Astrophysics Data System (ADS)

    Park, Chang Seok; Lim, Hee Chang

    2015-11-01

    In general, the heated surface generates a Marangoni flow inside a droplet yielding a coffee stain effect in the end. This study aims to visualize and control the Marangoni flow by using periodic vertical vibration. While the droplet is evaporating, the variation of contact angle and internal volume of droplet was observed by using the combination of a continuous light and a DSLR still camera. Regarding the internal velocity, the PIV(Particle Image Velocimetry) system was applied to visualize the internal Marangoni flow. In order to estimate the temperature gradient inside and surface tension on the droplet, a commercial software Comsol Multiphysics was used. In the result, the internal velocity increases with the increase of the plate temperature and both flow directions of Marangoni and gravitational flow are opposite so that there seems to be a possibility to control the coffee stain effect. In addition, the Marangoni flow was controlled at relatively lower range of frequency 30 ~ 50Hz. Work supported by Korea government Ministry of Trade, Industry and Energy KETEP grant No. 20134030200290, Ministry of Education NRF grant No. NRF2013R1A1A2005347.

  10. Heat transfer analysis in a second grade fluid over and oscillating vertical plate using fractional Caputo-Fabrizio derivatives

    NASA Astrophysics Data System (ADS)

    Shah, Nehad Ali; Khan, Ilyas

    2016-07-01

    This paper presents a Caputo-Fabrizio fractional derivatives approach to the thermal analysis of a second grade fluid over an infinite oscillating vertical flat plate. Together with an oscillating boundary motion, the heat transfer is caused by the buoyancy force induced by temperature differences between the plate and the fluid. Closed form solutions of the fluid velocity and temperature are obtained by means of the Laplace transform. The solutions of ordinary second grade and Newtonian fluids corresponding to time derivatives of integer and fractional orders are obtained as particular cases of the present solutions. Numerical computations and graphical illustrations are used in order to study the effects of the Caputo-Fabrizio time-fractional parameter α, the material parameter α _2 , and the Prandtl and Grashof numbers on the velocity field. A comparison for time derivative of integer order versus fractional order is shown graphically for both Newtonian and second grade fluids. It is found that fractional fluids (second grade and Newtonian) have highest velocities. This shows that the fractional parameter enhances the fluid flow.

  11. Heat Transfer Mechanism of a Vertical Wall Inside a Two-Phase Closed Thermosiphon Evaporator and Its Estimation

    NASA Astrophysics Data System (ADS)

    O-Uchi, Masaki; Hirose, Koichi; Saito, Futami

    The inside heat transfer coefficient, overall heat transfer coefficient, and heat flow rate at the heating section of the thermosiphon were determined for each heating method. In order to observe the heat transfer mechanism in the evaporator, a thermosiphon unit made of glass was assembled and conducted separately. The results of these experiments with these two units are summarized as follows. (1) Nucleate boiling due to the internal heat transfer mechanism improves the heat transfer characteristics of the thermosiphon unit. Under the specific heating conditions with dropwise condensation, there are two types of heat transfer mechanism occur in the evaporator accompanying nucleate boiling, i. e. latent heat transfer and sensible heat transfer. (2) In the case of latent heat transfer, the inside heat transfer coefficient has an upper limit which can be used as a criterion to determine the type of internal heat transfer mechanism.

  12. Convection heat transfer of CO{sub 2} at supercritical pressures in a vertical mini tube at relatively low reynolds numbers

    SciTech Connect

    Jiang, Pei-Xue; Zhang, Yu.; Zhao, Chen-Ru; Shi, Run-Fu

    2008-09-15

    Convection heat transfer of CO{sub 2} at supercritical pressures in a 0.27 mm diameter vertical mini tube was investigated experimentally and numerically for upward and downward flows at relatively low inlet Reynolds numbers (2900 and 1900). The effects of inlet temperature, pressure, mass flow rate, heat flux, flow direction, buoyancy and flow acceleration on the convection heat transfer were investigated. For inlet Reynolds numbers less than 2.9 x 10{sup 3}, the local wall temperature varies non-linearly for both flow directions at high heat fluxes (113 kW/m{sup 2}). For the mini tube used in the current study, the buoyancy effect is normally low even when the heating is relatively strong, while the flow acceleration due to heating can strongly influence the turbulence and reduce the heat transfer for high heat fluxes. For relatively low Reynolds numbers (Re{sub in} {<=} 2.9 x 10{sup 3}) and the low heat flux (30.0 kW/m{sup 2}) the predicted values using the LB low Reynolds number correspond well with the measured data. However, for the high heat flux (113 kW/m{sup 2}), the predicted values do not correspond well with the measured data due to the influence of the flow acceleration on the turbulence. (author)

  13. Impact of black carbon aerosol over Italian basin valleys: high-resolution measurements along vertical profiles, radiative forcing and heating rate

    NASA Astrophysics Data System (ADS)

    Ferrero, L.; Castelli, M.; Ferrini, B. S.; Moscatelli, M.; Perrone, M. G.; Sangiorgi, G.; D'Angelo, L.; Rovelli, G.; Moroni, B.; Scardazza, F.; Močnik, G.; Bolzacchini, E.; Petitta, M.; Cappelletti, D.

    2014-09-01

    A systematic study of black carbon (BC) vertical profiles measured at high-resolution over three Italian basin valleys (Terni Valley, Po Valley and Passiria Valley) is presented. BC vertical profiles are scarcely available in literature. The campaign lasted 45 days and resulted in 120 measured vertical profiles. Besides the BC mass concentration, measurements along the vertical profiles also included aerosol size distributions in the optical particle counter range, chemical analysis of filter samples and a full set of meteorological parameters. Using the collected experimental data, we performed calculations of aerosol optical properties along the vertical profiles. The results, validated with AERONET data, were used as inputs to a radiative transfer model (libRadtran). The latter allowed an estimation of vertical profiles of the aerosol direct radiative effect, the atmospheric absorption and the heating rate in the lower troposphere. The present measurements revealed some common behaviors over the studied basin valleys. Specifically, at the mixing height, marked concentration drops of both BC (range: from -48.4 ± 5.3 to -69.1 ± 5.5%) and aerosols (range: from -23.9 ± 4.3 to -46.5 ± 7.3%) were found. The measured percentage decrease of BC was higher than that of aerosols: therefore, the BC aerosol fraction decreased upwards. Correspondingly, both the absorption and scattering coefficients decreased strongly across the mixing layer (range: from -47.6 ± 2.5 to -71.3 ± 3.0% and from -23.5 ± 0.8 to -61.2 ± 3.1%, respectively) resulting in a single-scattering albedo increase along height (range: from +4.9 ± 2.2 to +7.4 ± 1.0%). This behavior influenced the vertical distribution of the aerosol direct radiative effect and of the heating rate. In this respect, the highest atmospheric absorption of radiation was predicted below the mixing height (~ 2-3 times larger than above it) resulting in a heating rate characterized by a vertical negative gradient (range

  14. Direct measurements of vertical heat flux and Na flux in the mesosphere and lower thermosphere by lidar at Boulder (40°N, 105°W), Colorado

    NASA Astrophysics Data System (ADS)

    Huang, W.; Chu, X.; Gardner, C. S.; Barry, I. F.; Smith, J. A.; Fong, W.; Yu, Z.; Chen, C.

    2014-12-01

    The vertical transport of heat and constituent by gravity waves and tides plays a fundamental role in establishing the thermal and constituent structures of the mesosphere and lower thermosphere (MLT), but has not been thoroughly investigated by observations. In particular, direct measurements of vertical heat flux and metal constituent flux caused by dissipating waves are extremely rare, which demand precise measurements with high spatial and temporal resolutions over a long period. Such requirements are necessary to overcome various uncertainties to reveal the small quantities of the heat and constituent fluxes induced by dissipating waves. So far such direct observations have only been reported for vertical heat and Na fluxes using a Na Doppler lidar at Starfire Optical Range (SOR) in Albuquerque, New Mexico. Furthermore, estimate of eddy heat and constituent fluxes from the turbulent mixing generated by breaking waves is even more challenging due to the even smaller temporal and spatial scales of the eddy. Consequently, the associated coefficients of thermal (kH) and constituent (kzz) diffusion have not been well characterized and remain as large uncertainties in models. We attempt to address these issues with direct measurements by a Na Doppler lidar with exceptional high-resolution measurement capabilities. Since summer 2010, we have been operating a Na Doppler lidar at Boulder, Colorado. The efficiency of the lidar has been greatly improved in summer of 2011 and achieved generally over 1000 counts of Na signal per lidar pulse in winter. In 2013, we made extensive Na lidar observations in 98 nights. These data covering each month of a full year will be used to characterize the seasonal variations of heat and Na fluxes and to be compared with the pioneering observations at SOR. In November 2013, we further upgraded the lidar with two new frequency shifters and a new data acquisition scheme, which are optimized for estimating eddy fluxes and reducing the

  15. Ground coupling and single-blow thermal storage in a double-envelope house

    SciTech Connect

    Ghaffari, H T; Jones, R F

    1981-01-01

    The possibility of ground thermal storage and coupling in a double-shell house is investigated. Temperature distribution in the ground, utilizing measured ground temperatures, is obtained, and the amount of heat retrieval is assessed. One experimental model and several hypothetical models are introduced; their effects and advantages are compared.

  16. Nonlinear Radiation Heat Transfer Effects in the Natural Convective Boundary Layer Flow of Nanofluid Past a Vertical Plate: A Numerical Study

    PubMed Central

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge–Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

  17. Analysis of fluid motion and heat transport on magnetohydrodynamic boundary layer past a vertical power law stretching sheet with hydrodynamic and thermal slip effects

    NASA Astrophysics Data System (ADS)

    Alkahtani, Badr; Abel, M. Subhas; Aly, Emad H.

    2015-12-01

    The present model is committed to the study of MHD boundary layer flow and heat transfer past a nonlinear vertically stretching porous stretching sheet with the effects of hydrodynamic and thermal slip. The boundary value problem, consisting of boundary layer equations of motion and heat transfer, which are nonlinear partial differential equations are transformed into nonlinear ordinary differential equations, with the aid of similarity transformation. This problem has been solved, using Runge Kutta fourth order method with shooting technique. The effects of various physical parameters, such as, stretching parameter m, magnetic parameter M, porosity parameter fw, buoyancy parameter λ, Prandtl number Pr, Eckert number Ec, hydrodynamic slip parameter γ, and thermal slip parameter δ, on flow and heat transfer characteristics, are computed and represented graphically.

  18. The effect of transpiration on coupled heat and mass transfer in mixed convection over a vertical plate embedded in a saturated porous medium

    SciTech Connect

    Yih, K.A.

    1997-03-01

    Effect of transpiration velocity on the heat and mass transfer characteristics of mixed convection about a permeable vertical plate embedded in a saturated porous medium under the coupled effects of thermal and mass diffusion is numerically analyzed. The plate is maintained at a uniform temperature and species concentration with constant transpiration velocity. The transformed governing equations are solved by Keller box method. Numerical results for the local Nusselt number and local Sherwood number are presented. In general, it has been found for thermally assisted flow that the local surface heat and mass transfer rates increase owing to suction of fluid. This trend reversed for blowing of fluid. It is apparent that the Lewis number has a pronounced effect on the local Sherwood number than it does on the local Nusselt number. Increasing the Lewis number decreases (increases) the local heat (mass) transfer rate.

  19. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    DOE PAGESBeta

    Hollmann, E. M.; Commaux, N.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, D.

    2015-10-12

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma current channel is seen to lock to a preferential phase during the VDE thermal quench, but this phasemore » is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Finally, clear indications of plasma infra-red emission are observed both before and during the disruptions; this infrared emission can affect calculation of disruption heat loads.« less

  20. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    PubMed

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter.

  1. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    SciTech Connect

    Hollmann, E. M.; Commaux, N.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, D.

    2015-10-12

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma current channel is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Finally, clear indications of plasma infra-red emission are observed both before and during the disruptions; this infrared emission can affect calculation of disruption heat loads.

  2. Nonlinear radiation heat transfer effects in the natural convective boundary layer flow of nanofluid past a vertical plate: a numerical study.

    PubMed

    Mustafa, Meraj; Mushtaq, Ammar; Hayat, Tasawar; Ahmad, Bashir

    2014-01-01

    The problem of natural convective boundary layer flow of nanofluid past a vertical plate is discussed in the presence of nonlinear radiative heat flux. The effects of magnetic field, Joule heating and viscous dissipation are also taken into consideration. The governing partial differential equations are transformed into a system of coupled nonlinear ordinary differential equations via similarity transformations and then solved numerically using the Runge-Kutta fourth-fifth order method with shooting technique. The results reveal an existence of point of inflection for the temperature distribution for sufficiently large wall to ambient temperature ratio. Temperature and thermal boundary layer thickness increase as Brownian motion and thermophoretic effects intensify. Moreover temperature increases and heat transfer from the plate decreases with an increase in the radiation parameter. PMID:25251242

  3. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    SciTech Connect

    Hollmann, E. M.; Commaux, Nicolas J. C.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, Daisuke

    2015-10-12

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. Furthermore, this IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  4. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    SciTech Connect

    Hollmann, E. M.; Moyer, R. A.; Commaux, N.; Shiraki, D.; Eidietis, N. W.; Parks, P. B.; Lasnier, C. J.

    2015-10-15

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but this phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. This IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.

  5. Vertical distributions of uranium, thorium and potassium and of volumetric heat production rates in the sediments of the São Francisco Basin, Central Brazil.

    PubMed

    Ribeiro, F B; Roque, A

    2001-09-01

    Uranium, thorium and potassium measurements and volumetric heat production rate calculations were made in Bambui Group Neoproterozoic sedimentary rocks from the São Francisco Basin, central Brazil. The measurements were made from drilling cuttings from two deep wells drilled near the cities of Alvorada do Norte, northeast Goiás State, and Montalvânia, north of Minas Gerais State. The obtained results allowed the construction of the vertical profiles depicting the abundances of heat generating elements, of the heat production rate and of U/Th, U/K and Th/K ratios in these sediments. These profiles, which reflect both the lithology and the sediment history. are used to interpret some aspects of the Bambui Group sedimentation sequence.

  6. Excellent scalability including self-heating phenomena of vertical-channel field-effect-diode type capacitor-less one transistor dynamic random access memory cell

    NASA Astrophysics Data System (ADS)

    Imamoto, Takuya; Endoh, Tetsuo

    2014-01-01

    The scalability study and the impact of the self-heating effect (SHE) on memory operation of the bulk vertical-channel field effect diode (FED) type capacitorless one transistor (1T) dynamic random access memory (DRAM) cell are investigated via device simulator for the first time. The vertical-channel FED type 1T-DRAM cell shows the excellent hold characteristics (100 ms at 358 K of ambient temperature) with large enough read current margin (1 µA/cell) even when silicon pillar diameter (D) is scaled down from 20 to 12 nm. It is also shown that by employing the vertical-channel FED type, maximum lattice temperature in the memory cell due to SHE (T_{\\text{L}}^{\\text{Max}}) can be suppressed to a negligible small value and only reach 300.6 from 300 K ambient temperature due to the low lateral electric field, while the vertical-channel bipolar junction transistor (BJT) type 1T-DRAM shows significant SHE (T_{\\text{L}}^{\\text{Max}} = 330.6 K). Moreover, this excellent thermal characteristic can be maintained even when D is scaled down from 20 to 12 nm.

  7. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs. S. America ) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model. Review of other latent heating algorithms will be discussed in the workshop.

  8. Comparison of air-launched and ground-coupled configurations of SFCW GPR in time, frequency and wavelet domain

    NASA Astrophysics Data System (ADS)

    Van De Vijver, Ellen; De Pue, Jan; Cornelis, Wim; Van Meirvenne, Marc

    2015-04-01

    A stepped frequency continuous wave (SFCW) ground penetrating radar (GPR) system produces waveforms consisting of a sequence of sine waves with linearly increasing frequency. By adopting a wide frequency bandwidth, SFCW GPR systems offer an optimal resolution at each achievable measurement depth. Furthermore, these systems anticipate an improved penetration depth and signal-to-noise ratio (SNR) as compared to time-domain impulse GPRs, because energy is focused in one single frequency at a time and the phase and amplitude of the reflected signal is recorded for each discrete frequency step. However, the search for the optimal practical implementation of SFCW GPR technology to fulfil these theoretical advantages is still ongoing. In this study we compare the performance of a SFCW GPR system for air-launched and ground-coupled antenna configurations. The first is represented by a 3d-Radar Geoscope GS3F system operated with a V1213 antenna array. This array contains 7 transmitting and 7 receiving antennae resulting in 13 measurement channels at a spacing of 0.075 m and providing a total scan width of 0.975 m. The ground-coupled configuration is represented by 3d-Radar's latest-generation SFCW system, GeoScope Mk IV, operated with a DXG1212 antenna array. With 6 transmitting and 5 receiving antennae this array provides 12 measurement channels and an effective scan width of 0.9 m. Both systems were tested on several sites representative of various application environments, including a test site with different road specimens (Belgian Road Research Centre) and two test areas in different agricultural fields in Flanders, Belgium. For each test, data acquisition was performed using the full available frequency bandwidth of the systems (50 to 3000 MHz). Other acquisition parameters such as the frequency step and dwell time were varied in different tests. Analyzing the data of the different tests in time, frequency and wavelet domain allows to evaluate different performance

  9. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. Additional information is included in the original extended abstract.

  10. Vertical Profiles of Latent Heat Release Over the Global Tropics using TRMM Rainfall Products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.; Starr, David (Technical Monitor)

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in stratiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  11. Vertical Profiles of Latent Heat Release over the Global Tropics Using TRMM Rainfall Products from December 1997 to November 2002

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.

    2003-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2000. Rainfall, latent heating and radar reflectivity structures between El Nino (DJF 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs west Pacific, Africa vs S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in straitform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMXX), Brazil in 1999 (TRMM- LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  12. Vertical Profiles of Latent Heat Release over the Global Tropics using TRMM rainfall products from December 1997 to November 2001

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Lang, S.; Simpson, J.; Meneghini, R.; Halverson, J.; Johnson, R.; Adler, R.

    2002-01-01

    NASA Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) derived rainfall information will be used to estimate the four-dimensional structure of global monthly latent heating and rainfall profiles over the global tropics from December 1997 to November 2001. Rainfall, latent heating and radar reflectivity structures between El Nino (DE 1997-98) and La Nina (DJF 1998-99) will be examined and compared. The seasonal variation of heating over various geographic locations (i.e., oceanic vs continental, Indian ocean vs. west Pacific, Africa vs. S. America) will also be analyzed. In addition, the relationship between rainfall, latent heating (maximum heating level), radar reflectivity and SST is examined and will be presented in the meeting. The impact of random error and bias in strtaiform percentage estimates from PR on latent heating profiles is studied and will also be presented in the meeting. The Goddard Cumulus Ensemble Model is being used to simulate various mesoscale convective systems that developed in different geographic locations. Specifically, the model estimated rainfall, radar reflectivity and latent heating profiles will be compared to observational data collected from TRMM field campaigns over the South China Sea in 1998 (SCSMEX), Brazil in 1999 (TRMM-LBA), and the central Pacific in 1999 (KWAJEX). Sounding diagnosed heating budgets and radar reflectivity from these experiments can provide the means to validate (heating product) as well as improve the GCE model.

  13. Heat Budget Calculation in the Convective Boundary Layer on a 4 × 4 Vertical versus Time Grid from Aircraft and Surface Measurements.

    NASA Astrophysics Data System (ADS)

    Lukas, John C.

    2000-09-01

    Aircraft, portable tower, and radiosonde measurements from 4 August 1989 (day 68) of the First International Satellite Land Surface Climatology Project (ISLCP) Field Experiment (FIFE), over fairly flat terrain in Kansas, are used for the reconstruction of the heat conservation equation. The calculation grid consists of three grouped flight levels and the surface, and three 1-h blocks, within the midday convective boundary layer (CBL). The day chosen had a week warm front disturbance in addition to the usual summertime southern flow over the midwestern United States. Significant vertical and temporal structure, which should not be bulk averaged, was observed for all terms. The upper layer showed warming sustained at a constant rate around noon and appeared decoupled from the surface and the middle levels in the later hours. Excess warming was due to advection and possibly entrainment. Consequently, the heat flux divergence also had a nonzero vertical gradient. Advection proves to be an important term and does not average out when driven by a synoptic feature. Its east-west component improved the balance of the heat equation at all levels. Partial flight intertrack and total CBL volume standard deviations for terms and residuals are carried through explicitly.

  14. Ground-coupled acoustic airwaves from Mount St. Helens provide constraints on the May 18, 1980 eruption

    NASA Astrophysics Data System (ADS)

    Johnson, Jeffrey B.; Malone, Stephen D.

    2007-06-01

    The May 18, 1980 Mount St. Helens eruption perturbed the atmosphere and generated atmosphere-to-ground coupled airwaves, which were recorded on at least 35 seismometers operated by the Pacific Northwest Seismograph Network (PNSN). From 102 distinct travel time picks we identify coherent airwaves crossing Washington State primarily to the north and east of the volcano. The travel time curves provide evidence for both stratospheric refractions (at 200 to 300 km from the volcano) as well as probable thermospheric refractions (at 100 to 350 km). The very few first-hand reports of audible volcano sounds within about 80 km of the volcano coincide with a general absence of ground-coupled acoustic arrivals registered within about 100 km and are attributed to upward refraction of sound waves. From the coherent refracted airwave arrivals, we identify at least four distinct sources which we infer to originate 10 s, 114 s, ˜ 180 s and 319 s after the onset of an 8:32:11 PDT landslide. The first of these sources is attributed to resultant depressurization and explosion of the cryptodome. Most of the subsequent arrivals also appear to be coincident with a source located at or near the presumed volcanic conduit, but at least one of the later arrivals suggests an epicenter displaced about 9 km to the northwest of the vent. This dislocation is compatible with the direction of the sector collapse and lateral blast. We speculate that this concussion corresponds to a northern explosion event associated with hot cryptodome entering the Toutle River Valley.

  15. Ground-coupled acoustic airwaves from Mount St. Helens provide constraints on the May 18, 1980 eruption

    USGS Publications Warehouse

    Johnson, J.B.; Malone, S.D.

    2007-01-01

    The May 18, 1980 Mount St. Helens eruption perturbed the atmosphere and generated atmosphere-to-ground coupled airwaves, which were recorded on at least 35 seismometers operated by the Pacific Northwest Seismograph Network (PNSN). From 102 distinct travel time picks we identify coherent airwaves crossing Washington State primarily to the north and east of the volcano. The travel time curves provide evidence for both stratospheric refractions (at 200 to 300 km from the volcano) as well as probable thermospheric refractions (at 100 to 350 km). The very few first-hand reports of audible volcano sounds within about 80 km of the volcano coincide with a general absence of ground-coupled acoustic arrivals registered within about 100 km and are attributed to upward refraction of sound waves. From the coherent refracted airwave arrivals, we identify at least four distinct sources which we infer to originate 10 s, 114 s, ∼ 180 s and 319 s after the onset of an 8:32:11 PDT landslide. The first of these sources is attributed to resultant depressurization and explosion of the cryptodome. Most of the subsequent arrivals also appear to be coincident with a source located at or near the presumed volcanic conduit, but at least one of the later arrivals suggests an epicenter displaced about 9 km to the northwest of the vent. This dislocation is compatible with the direction of the sector collapse and lateral blast. We speculate that this concussion corresponds to a northern explosion event associated with hot cryptodome entering the Toutle River Valley.

  16. Influence of Soret, Hall and Joule heating effects on mixed convection flow saturated porous medium in a vertical channel by Adomian Decomposition Method

    NASA Astrophysics Data System (ADS)

    Reddy, Ch. Ram; Kaladhar, K.; Srinivasacharya, D.; Pradeepa, T.

    2016-02-01

    This paper analyzes the laminar, incompressible mixed convective transport inside vertical channel in an electrically conducting fluid saturated porous medium. In addition, this model incorporates the combined effects of Soret, Hall current and Joule heating. The nonlinear governing equations and their related boundary conditions are initially cast into a dimensionless form using suitable similarity transformations and hence solved using Adomian Decomposition Method (ADM). In order to explore the influence of various parameters on fluid flow properties, quantitative analysis is exhibited graphically and shown in tabular form.

  17. Various computational conditions of oscillatory natural convection of zero Prandtl number fluid in an open boat heated and cooled from opposing vertical walls

    SciTech Connect

    Okada, Kazuto . Interdisciplinary Graduate School of Engineering Science); Ozoe, Hiroyuki . Inst. of Advanced Material Study)

    1993-03-01

    The finite-difference computational scheme is developed for two-dimensional oscillatory natural convection of zero Prandtl number fluid in an open boat heated and cooled from opposing vertical walls. Various computational conditions are tested, such as the initial condition, time step length, finite-difference width, and finite-difference scheme. Instantaneous contour maps and velocity vectors in oscillatory states are presented in a series of maps to represent the fluctuating characteristics of two-dimensional roll cells. The physical conditions are for a boat with aspect ratio A = 3[minus]5 at Pr = 0 and Gr = 14,000-40,000.

  18. Experimental Investigation on the Heat Transfer Characteristics in a Vertical Upward Flow of Supercritical CO{sub 2}

    SciTech Connect

    Hyungrae Kim; Yoon Yeong Bae; Hwan Yeol Kim; Jin Ho Song; Bong Hyun Cho

    2006-07-01

    The SCWR (Supercritical Water-cooled Reactor) is one of the feasible options for the 4. generation nuclear power plant, which is being pursued by an international collaborative organization, the Gen IV International Forum (GIF). The major advantages of the SCWR include a high thermal efficiency and a maximum use of the existing technologies. In the SCWR, the coolant(water) of a supercritical pressure passes the pseudo-critical temperature as it flows upward through the sub-channels of the fuel assemblies. At certain conditions a heat transfer deterioration may occur near the pseudo-critical temperature and it may cause an excessive rise of the fuel surface temperature. Therefore, an accurate estimation of the heat transfer coefficient is necessary for the thermal-hydraulic design of a fuel pin, a fuel assembly, and the reactor core. A test facility, SPHINX, dedicated to produce heat transfer data and study flow characteristics, uses supercritical pressure CO{sub 2} as a medium to take advantage of the relatively low critical temperature and pressure; and similar physical properties with water. The produced data includes the temperature of the heating surface, the heat transfer coefficient, and the pressure drop at varying mass fluxes, heat fluxes, and operating pressures. The test section is a circular tube of ID 4.4 mm. The test range of the mass flux is 400 {approx} 1200 kg/m{sup 2}s and the maximum heat flux is 150 kW/m{sup 2}. The tests were performed for three different pressures, 7.75, 8.12, and 8.85 MPa. The test results are compared with the existing correlations of the heat transfer coefficient. In addition, the deterioration conditions observed in our test are compared against the criteria for a different fluid or a different tube size. (authors)

  19. Forced and mixed convection heat transfer to supercritical CO{sub 2} vertically flowing in a uniformly-heated circular tube

    SciTech Connect

    Bae, Yoon-Yeong; Kim, Hwan-Yeol; Kang, Deog-Ji

    2010-11-15

    An experiment of heat transfer to CO{sub 2}, which flows upward and downward in a circular tube with an inner diameter of 6.32 mm, was carried out with mass flux of 285-1200 kg/m{sup 2} s and heat flux of 30-170 kW/m{sup 2} at pressures of 7.75 and 8.12 MPa, respectively. The corresponding Reynolds number at the tube test section inlet ranges from 1.8 x 10{sup 4} to 3.8 x 10{sup 5}. The tube inner diameter corresponds to the equivalent hydraulic diameter of the fuel assembly sub-channel, which is being studied at KAERI. Among the tested correlations, the Bishop correlation predicted the experimental data most accurately, but only 66.9% of normal heat transfer data were predicted within {+-}30% error range. The Watts and Chou correlation, which is claimed to be valid for both the normal and deteriorated heat transfer regime, showed unsatisfactory performance. A significant decrease in Nusselt number was observed in the range of 10{sup -6}heat transfer deterioration regime. The heat transfer deteriorated when the value of the buoyancy parameter Gr{sub b}/Re{sub b}{sup 2.7} exceeded 2.0 x 10{sup -5} close to the Jackson and Hall's criterion. As soon as the heat transfer deteriorated, it entered a new regime and did not return to a normal heat transfer regime, although the value of buoyancy parameter Gr{sub b}/Re{sub b}{sup 2.7} reduced below the deterioration criterion 2.0 x 10{sup -5}. It may justify the requirement of developing separate correlations for the normal and deterioration regimes, as proposed in this paper. (author)

  20. Effect of sea-ice melt on inherent optical properties and vertical distribution of solar radiant heating in Arctic surface waters

    NASA Astrophysics Data System (ADS)

    Granskog, Mats A.; Pavlov, Alexey K.; Sagan, Sławomir; Kowalczuk, Piotr; Raczkowska, Anna; Stedmon, Colin A.

    2015-10-01

    The inherent optical properties (IOPs) of Polar Waters (PW) exiting the Arctic Ocean in the East Greenland Current (EGC) and of the inflowing Atlantic waters (AW) in the West Spitsbergen Current (WSC) were studied in late summer when surface freshening due to sea-ice melt was widespread. The absorption and attenuation coefficients in PW were significantly higher than previous observations from the western Arctic. High concentrations of colored dissolved organic matter (CDOM) resulted in 50-60% more heat deposition in the upper meters relative to clearest natural waters. This demonstrates the influence of terrigenous organic material inputs on the optical properties of waters in the Eurasian basin. Sea-ice melt in CDOM-rich PW decreased CDOM absorption, but an increase in scattering nearly compensated for lower absorption, and total attenuation was nearly identical in the sea-ice meltwater layer. This suggests a source of scattering material associated with sea-ice melt, relative to the PW. In the AW, melting sea-ice forms a stratified surface layer with lower absorption and attenuation, than well-mixed AW waters in late summer. It is likely that phytoplankton in the surface layer influenced by sea-ice melt are nutrient limited. The presence of a more transparent surface layer changes the vertical radiant heat absorption profile to greater depths in late summer both in EGC and WSC waters, shifting accumulation of solar heat to greater depths and thus this heat is not directly available for ice melt during periods of stratification.

  1. Investigations of heat transfer, entropy generation and pressure build up for upward flow in a vertical channel equipped with a fin array

    NASA Astrophysics Data System (ADS)

    Nemitallah, Medhat A.; Zohir, Alaa E.

    2016-09-01

    The optimal thermal systems design criteria by maximizing the amount of heat transfer per pressure losses is a very important topic. In this work, flow and convection and radiation heat transfer characteristics are studied numerically for a flow in a vertical channel equipped with transverse fin array. The influences of fin height on heat transfer characteristics and fluid flow is investigated. Large number of fins is used (40 fins) in order to reach the fully developed conditions after few fins from the entrance. Based on the calculated data of temperature and velocity, the local entropy generation is calculated through the whole channel by solving the entropy generation equation. The results are validated against the available data in the literature and both results are in a good agreement. Optimizations for flow conditions and channel geometry are performed in order to obtain maximum heat transfer per pumping power losses. The results showed that the highest values of total heat transfer per pumping power losses are obtained at fin height to the gap width values of 0.1 and 0.3. The effect of heat transfer by radiation on entropy generation is examined and, the effect of the ratio, Gr/Re2, on the pressure field is also investigated. It was found that a positive pressure gradient appears downstream in the channel when the value of Gr/Re2 exceeds a certain limit. For Gr/Re2 values between 0 and 9, the pressure gradient is negative; however, when the value Gr/Re2 exceeds 9, the pressure starts to build up through the channel axis.

  2. Convective heat transfer to CO{sub 2} at a supercritical pressure flowing vertically upward in tubes and an annular channel

    SciTech Connect

    Bae, Yoon-Yeong; Kim, Hwan-Yeol

    2009-01-15

    The Super-Critical Water-Cooled Reactor (SCWR) has been chosen by the Generation IV International Forum as one of the candidates for the next generation nuclear reactors. Heat transfer to water from a fuel assembly may deteriorate at certain supercritical pressure flow conditions and its estimation at degraded conditions as well as in normal conditions is very important to the design of a safe and reliable reactor core. Extensive experiments on a heat transfer to a vertically upward flowing CO{sub 2} at a supercritical pressure in tubes and an annular channel have been performed. The geometries of the test sections include tubes of an internal diameter (ID) of 4.4 and 9.0 mm and an annular channel (8 x 10 mm). The heat transfer coefficient (HTC) and Nusselt numbers were derived from the inner wall temperature converted by using the outer wall temperature measured by adhesive K-type thermocouples and a direct (tube) or indirect (annular channel) electric heating power. From the test results, a correlation, which covers both a deteriorated and a normal heat transfer regime, was developed. The developed correlation takes different forms in each interval divided by the value of parameter Bu. The parameter Bu (referred to as Bu hereafter), a function of the Grashof number, the Reynolds number and the Prandtl number, was introduced since it is known to be a controlling factor for the occurrence of a heat transfer deterioration due to a buoyancy effect. The developed correlation predicted the HTCs for water and HCFC-22 fairly well. (author)

  3. Critical heat-flux experiments under low-flow conditions in a vertical annulus. [PWR; BWR; LMFBR

    SciTech Connect

    Mishima, K.; Ishii, M.

    1982-03-01

    An experimental study was performed on critical heat flux (CHF) at low flow conditions for low pressure steam-water upward flow in an annulus. The test section was transparent, therefore, visual observations of dryout as well as various instrumentations were made. The data indicated that a premature CHF occurred due to flow regime transition from churn-turbulent to annular flow. It is shown that the critical heat flux observed in the experiment is essentially similar to a flooding-limited burnout and the critical heat flux can be well reproduced by a nondimensional correlation derived from the previously obtained criterion for flow regime transition. The observed CHF values are much smaller than the standard high quality CHF criteria at low flow, corresponding to the annular flow film dryout. This result is very significant, because the coolability of a heater surface at low flow rates can be drastically reduced by the occurrence of this mode of CHF.

  4. Soret and Dufour Effects on MHD Free Convective Flow Past a Vertical Porous Plate in the Presence of Heat Generation

    NASA Astrophysics Data System (ADS)

    Reddy, G. V. R.

    2016-08-01

    An MHD fluid flow is examined over a vertical plate in the presence of Dufour and Soret effects. The resulting momentum, energy and concentration equations are then made similar by introducing the usual similarity transformations. These similar equations are then solved numerically using the Runge-Kutta fourth order method with shooting technique. The effects of various parameters on the dimensionless velocity, temperature and concentration profiles as well as the local values of the skin-friction coefficient, the Nusselt number and Sherwood number are displayed graphically and in a tabular form. A comparison with previously published work is obtained and an excellent agreement is found.

  5. Unsteady hydromagnetic flow of dusty fluid and heat transfer over a vertical stretching sheet with thermal radiation

    SciTech Connect

    Isa, Sharena Mohamad; Ali, Anati

    2015-10-22

    In this paper, the hydromagnetic flow of dusty fluid over a vertical stretching sheet with thermal radiation is investigated. The governing partial differential equations are reduced to nonlinear ordinary differential equations using similarity transformation. These nonlinear ordinary differential equations are solved numerically using Runge-Kutta Fehlberg fourth-fifth order method (RKF45 Method). The behavior of velocity and temperature profiles of hydromagnetic fluid flow of dusty fluid is analyzed and discussed for different parameters of interest such as unsteady parameter, fluid-particle interaction parameter, the magnetic parameter, radiation parameter and Prandtl number on the flow.

  6. Direct numerical simulation of heated CO2 flows at supercritical pressure in a vertical annulus at Re =8900

    NASA Astrophysics Data System (ADS)

    Bae, Joong Hun; Yoo, Jung Yul; McEligot, Donald M.

    2008-05-01

    The present study is concerned with thermal physics of the fluid at supercritical pressure (SCP) where many singular phenomena are observed in turbulent heat transfer due to severe property variations of the fluid. Direct numerical simulation is conducted for upward annular flows of CO2 at a pressure of 8MPa with a constant-heat-flux boundary condition imposed on the inner wall. All simulations are made at the inlet bulk Reynolds number of 8900 with particular attention being paid to the structure of the heated boundary layers at SCP. It is shown that most singular phenomena at SCP occur when the pseudocritical temperature arises between the heated wall and bulk fluid temperatures. The mean velocity profile near the heated wall shows no logarithmic distribution in the inertial subrange because a large reduction in the Reynolds shear stress occurs in the viscous region. The computational flow visualization reveals that alternating low- and high-speed streaks in the viscous region are not clearly observed when the wall temperature peak is realized due to significant heat transfer deterioration. These results strongly suggest that the ejection and sweep motions of the fluid in the viscous region become so weakened that turbulent boundary layers at SCP cannot be self-sustained in the presence of strong stabilizing effects of the variable-property and buoyancy. It is also shown that streaky thermal pattern remains no longer similar to that of the velocity boundary layer when these coherent motions are reduced in the viscous region. In the meanwhile, the predicted normalized temperature profile at SCP shows a nearly flat distribution outside the viscous region although substantial amount of the radial turbulent heat flux is predicted there. This singular phenomenon at SCP can be considered as comparable to a phase change phenomenon at subcritical pressure, where the internal energy of the fluid is increased without changing the fluid temperature. At SCP, this transition

  7. Natural convection of water-fine particle suspension in a rectangular cell heated and cooled from opposing vertical walls

    SciTech Connect

    Okada, Masashi; Kang, Chaedong; Oyama, Kazuya; Yano, Satoshi

    1999-07-01

    Experiments of a natural convection of a water-fine particle suspension in a rectangular cell which was headed from a vertical wall and cooled from the opposing vertical wall were carried out. The suspension was a mixture of micro beads and water. Two kinds of particles were used. One was the micro beads made of soda glass of which specific gravity was 2.5. Mean diameter of the particle was 5.85{micro}m and standard deviation was 2.65{micro}m. It was considered that this particle size distribution was wide relatively. The other was micro beads made of SiO{sub 2} of which specific gravity was 2.15. Mean diameter of the particles was 2.97{micro}m and the standard deviation was 0.033{micro}m. This particle size distribution was considered to be narrow relatively. In the case of the suspension with particles whose size distribution is wide, many layers separated by almost-horizontal sharp interfaces were observed. In the beginning many layers appeared, and each interface of the layers fell gradually with a constant velocity, and finally all layers vanished. In the case of the suspension with the particles whose size distribution is narrow many layers were not formed but three layers were. The location of the interface was measured by video camera and at that time the temperature distribution in the vertical direction along the centerline of the test cell was measured. Furthermore the mean diameter and concentration of beads in each layer of the suspension were measured. In the above measurements the following results were obtained. The falling velocity of the interface becomes smaller as the initial concentration of particles becomes larger and the lower interface has the larger falling velocity. Each layer has a circular flow and each flow in a layer does not go into neighboring layers. The concentration of particles in each layer is almost uniform and the lower layer has the larger concentration and the larger mean diameter of particles. When the particle size

  8. Exergy Analysis of a Two-Stage Ground Source Heat Pump with a Vertical Bore for Residential Space Conditioning under Simulated Occupancy

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D.; Baxter, Van D.; Gehl, Anthony C.

    2015-06-26

    This twelve-month field study analyzes the performance of a 7.56W (2.16- ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m2 house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4°C and 21.7°C, respectively. The WA-GSHP shared the same 94.5 m vertical bore ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work are identified using Exergy and energy analysis. Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources.

  9. Exergy Analysis of a Two-Stage Ground Source Heat Pump with a Vertical Bore for Residential Space Conditioning under Simulated Occupancy

    DOE PAGESBeta

    Ally, Moonis Raza; Munk, Jeffrey D.; Baxter, Van D.; Gehl, Anthony C.

    2015-06-26

    This twelve-month field study analyzes the performance of a 7.56W (2.16- ton) water-to-air-ground source heat pump (WA-GSHP) to satisfy domestic space conditioning loads in a 253 m2 house in a mixed-humid climate in the United States. The practical feasibility of using the ground as a source of renewable energy is clearly demonstrated. Better than 75% of the energy needed for space heating was extracted from the ground. The average monthly electricity consumption for space conditioning was only 40 kWh at summer and winter thermostat set points of 24.4°C and 21.7°C, respectively. The WA-GSHP shared the same 94.5 m vertical boremore » ground loop with a separate water-to-water ground-source heat pump (WW-GSHP) for meeting domestic hot water needs in the same house. Sources of systemic irreversibility, the main cause of lost work are identified using Exergy and energy analysis. Quantifying the sources of Exergy and energy losses is essential for further systemic improvements. The research findings suggest that the WA-GSHPs are a practical and viable technology to reduce primary energy consumption and greenhouse gas emissions under the IECC 2012 Standard, as well as the European Union (EU) 2020 targets of using renewable energy resources.« less

  10. Mitigation of upward and downward vertical displacement event heat loads with upper or lower massive gas injection in DIII-D

    DOE PAGESBeta

    Hollmann, E. M.; Commaux, Nicolas J. C.; Eidietis, N. W.; Lasnier, C. J.; Moyer, R. A.; Parks, P. B.; Shiraki, Daisuke

    2015-10-12

    Intentionally triggered upward and downward vertical displacement events (VDEs) leading to disruptions were pre-emptively mitigated with neon massive gas injection (MGI) coming from either above or below the plasma. Global indicators of disruption mitigation effectiveness (conducted heat loads, radiated power, and vessel motion) do not show a clear improvement when mitigating with the gas jet located closer to the VDE impact area. A clear trend of improved mitigation is observed for earlier MGI timing relative to the VDE impact time. The plasma edge magnetic perturbation is seen to lock to a preferential phase during the VDE thermal quench, but thismore » phase is not clearly matched by preliminary attempts to fit to the conducted heat load phase. Clear indications of plasma infra-red (IR) emission are observed both before and during the disruptions. Furthermore, this IR emission can affect calculation of disruption heat loads; here, the time decay of post-disruption IR signals is used to correct for this effect.« less

  11. Measurement and simulation of ground-coupled air waves and diffracted infrasound from the Kokoxili Earthquake, 14th Nov. 2001

    NASA Astrophysics Data System (ADS)

    Guilbert, J.; Le Pichon, A.; Vallee, M.; Alcoverro, B.; Ulziibat, M.

    2002-12-01

    On November 14, 2001, a strong earthquake measuring Mm 7.8 occurred in the Qinghai Province (China). Coherent infrasonic waves were detected during more than one hour by the IS34 infrasound station in Mongolia (~1500 km from the epicenter). Using an appropriate acoustic propagation model, the inversion of the infrasonic measurements allows a precise localization of the secondary sources distribution along the Qinghai mountains. The predominant source of infrasound is likely ground-coupled air waves generated by the strong variations of topography due to energy carried out by surface seismic waves that travel from the epicenter region through the Qinghai mountains. To confirm the locations of these distant source regions, the pressure field has been reconstructed at IS34. For each element of the topography, a synthetic seismogram used as an input of the integral relation of Huygens-Rayleigh permits to estimate the pressure variation. The synthetic pressure field fit the recorded data in azimuth and in relative amplitude. These results confirm the hypothesis of a strong coupling between the Rayleigh waves and the atmosphere, as it has already been observed during the Arequipa earthquake of June 23rd 2001. The simulations also permit to validate the infrasonic propagation model. This favorable setting within a region of high mountains makes easier the evaluation of the relative contribution of the different source mechanisms involved in large earthquake.

  12. Heat transfer analysis of MHD thin film flow of an unsteady second grade fluid past a vertical oscillating belt.

    PubMed

    Gul, Taza; Islam, Saeed; Shah, Rehan Ali; Khan, Ilyas; Khalid, Asma; Shafie, Sharidan

    2014-01-01

    This article aims to study the thin film layer flowing on a vertical oscillating belt. The flow is considered to satisfy the constitutive equation of unsteady second grade fluid. The governing equation for velocity and temperature fields with subjected initial and boundary conditions are solved by two analytical techniques namely Adomian Decomposition Method (ADM) and Optimal Homotopy Asymptotic Method (OHAM). The comparisons of ADM and OHAM solutions for velocity and temperature fields are shown numerically and graphically for both the lift and drainage problems. It is found that both these solutions are identical. In order to understand the physical behavior of the embedded parameters such as Stock number, frequency parameter, magnetic parameter, Brinkman number and Prandtl number, the analytical results are plotted graphically and discussed.

  13. Heat transfer analysis of MHD thin film flow of an unsteady second grade fluid past a vertical oscillating belt.

    PubMed

    Gul, Taza; Islam, Saeed; Shah, Rehan Ali; Khan, Ilyas; Khalid, Asma; Shafie, Sharidan

    2014-01-01

    This article aims to study the thin film layer flowing on a vertical oscillating belt. The flow is considered to satisfy the constitutive equation of unsteady second grade fluid. The governing equation for velocity and temperature fields with subjected initial and boundary conditions are solved by two analytical techniques namely Adomian Decomposition Method (ADM) and Optimal Homotopy Asymptotic Method (OHAM). The comparisons of ADM and OHAM solutions for velocity and temperature fields are shown numerically and graphically for both the lift and drainage problems. It is found that both these solutions are identical. In order to understand the physical behavior of the embedded parameters such as Stock number, frequency parameter, magnetic parameter, Brinkman number and Prandtl number, the analytical results are plotted graphically and discussed. PMID:25383797

  14. Steady state boiling crisis in a helium vertically heated natural circulation loop - Part 1: Critical heat flux, boiling crisis onset and hysteresis

    NASA Astrophysics Data System (ADS)

    Furci, H.; Baudouy, B.; Four, A.; Meuris, C.

    2016-01-01

    Experiments were conducted on a 2-m high two-phase helium natural circulation loop operating at 4.2 K and 1 atm. The same loop was used in two experiments with different heated section internal diameter (10 and 6 mm). The power applied on the heated section wall was controlled in increasing and decreasing sequences, and temperature along the section, mass flow rate and pressure drop evolutions were recorded. The values of critical heat flux (CHF) were found at different positions of the test section, and the post-CHF regime was studied. The predictions of CHF by existing correlations were good in the downstream portion of the section, however CHF anomalies have been observed near the entrance, in the low quality region. In resonance with this, the re-wetting of the surface has distinct hysteresis behavior in each of the two CHF regions. Furthermore, hydraulics effects of crisis, namely on friction, were studied (Part 2). This research is the starting point to future works addressing transients conducing to boiling crisis in helium natural circulation loops.

  15. Effect of thermal-hydrogeological and borehole heat exchanger properties on performance and impact of vertical closed-loop geothermal heat pump systems

    NASA Astrophysics Data System (ADS)

    Dehkordi, S. Emad; Schincariol, Robert A.

    2013-10-01

    Ground-source geothermal systems are drawing increasing attention and popularity due to their efficiency, sustainability and being implementable worldwide. Consequently, design software and regulatory guidelines have been developed. Interaction with the subsurface significantly affects the thermal performance, sustainability, and impacts of such systems. Reviewing the related guidelines and the design software, room for improvement is evident, especially in regards to interaction with groundwater movement. In order to accurately evaluate the thermal effect of system and hydrogeological properties on a borehole heat exchanger, a fully discretized finite-element model is used. Sensitivity of the loop outlet temperatures and heat exchange rates to hydrogeological, system and meteorological factors (i.e. groundwater flux, thermal conductivity and volumetric heat capacity of solids, porosity, thermal dispersivity, grout thermal conductivity, background and inlet temperatures) are analyzed over 6-month and 25-year operation periods. Furthermore, thermal recovery during 25 years after system decommissioning has been modeled. The thermal plume development, transport and dissipation are also assessed. This study shows the importance of subsurface thermal conductivity, groundwater flow (flux > 10-7 m/s), and background and inlet temperature on system performance and impact. It also shows the importance of groundwater flow (flux > 10-8 m/s) on thermal recovery of the ground over other factors.

  16. Investigation of combined heat and mass transfer between vertical parallel plates in a two-layer flow of couple stress nanofluid

    NASA Astrophysics Data System (ADS)

    Khan, Najeeb Alam; Sultan, Faqiha; Riaz, Fatima; Jamil, Muhammad

    2016-02-01

    This study is an investigation of fully-developed laminar flow in a two-layer vertical channel; one part filled with couple stress nanofluid and the other part with clear couple stress fluid. The flow is examined for combined heat and mass transfer using uniform wall temperature and concentration boundary conditions. Optimal homotopy analysis method (OHAM) is used to solve the nonlinear coupled ordinary differential equations (ODEs) governing the flow in each region. This method is based on the homotopy analysis method (HAM)which is an effective method to analytically approximate the solution of highly nonlinear problems. The influence of pertinent parameters is observed on velocity, temperature, and concentration distributions, specifically, the effect of Brownian parameter on couple stress fluid is mentioned.

  17. On the Influence of Soret and Dufour Effects on MHD Free Convective Heat and Mass Transfer Flow over a Vertical Channel with Constant Suction and Viscous Dissipation

    PubMed Central

    Uwanta, Ime Jimmy; Usman, Halima

    2014-01-01

    The present paper investigates the combined effects of Soret and Dufour on free convective heat and mass transfer on the unsteady one-dimensional boundary layer flow over a vertical channel in the presence of viscous dissipation and constant suction. The governing partial differential equations are solved numerically using the implicit Crank-Nicolson method. The velocity, temperature, and concentration distributions are discussed numerically and presented through graphs. Numerical values of the skin-friction coefficient, Nusselt number, and Sherwood number at the plate are discussed numerically for various values of physical parameters and are presented through tables. It has been observed that the velocity and temperature increase with the increase in the viscous dissipation parameter and Dufour number, while an increase in Soret number causes a reduction in temperature and a rise in the velocity and concentration. PMID:27419208

  18. On demand shape-selective integration of individual vertical germanium nanowires on a Si(111) substrate via laser-localized heating.

    PubMed

    Ryu, Sang-Gil; Kim, Eunpa; Yoo, Jae-Hyuck; Hwang, David J; Xiang, Bin; Dubon, Oscar D; Minor, Andrew M; Grigoropoulos, Costas P

    2013-03-26

    Semiconductor nanowire (NW) synthesis methods by blanket furnace heating produce structures of uniform size and shape. This study overcomes this constraint by applying laser-localized synthesis on catalytic nanodots defined by electron beam lithography in order to accomplish site- and shape-selective direct integration of vertically oriented germanium nanowires (GeNWs) on a single Si(111) substrate. Since the laser-induced local temperature field drives the growth process, each NW could be synthesized with distinctly different geometric features. The NW shape was dialed on demand, ranging from cylindrical to hexagonal/irregular hexagonal pyramid. Finite difference time domain analysis supported the tunability of the light absorption and scattering spectra via controlling the GeNW shape.

  19. Influence of the Heat Treatment Duration on the Critical Temperature for the Break-Down of Vertical Bloch Line Chains

    NASA Astrophysics Data System (ADS)

    Han, Baoshan; R, Dahlbeck; Yuan, Yuling; J, Engemann

    1991-11-01

    For longer heat treatment duration (10 and 30 min), near and within the transition region, the softening fraction ρ has an obvious, but not very large increase and the increment for 30 min is greater than that for 10 min. As a result, the critical temperature T0 is only lowered by 2 similar 3°C for a typical sample. The above results indicate the existence of a quasi-static athermal instability, and the thermal activation of Bloch points is only of secondary importance.

  20. The relationship between latent heating, vertical velocity, and precipitation processes: The impact of aerosols on precipitation in organized deep convective systems

    NASA Astrophysics Data System (ADS)

    Tao, Wei-Kuo; Li, Xiaowen

    2016-06-01

    A high-resolution, two-dimensional cloud-resolving model with spectral-bin microphysics is used to study the impact of aerosols on precipitation processes in both a tropical oceanic and a midlatitude continental squall line with regard to three processes: latent heating (LH), cold pool dynamics, and ice microphysics. Evaporative cooling in the lower troposphere is found to enhance rainfall in low cloud condensation nuclei (CCN) concentration scenarios in the developing stages of a midlatitude convective precipitation system. In contrast, the tropical case produced more rainfall under high CCN concentrations. Both cold pools and low-level convergence are stronger for those configurations having enhanced rainfall. Nevertheless, latent heat release is stronger (especially after initial precipitation) in the scenarios having more rainfall in both the tropical and midlatitude environment. Sensitivity tests are performed to examine the impact of ice and evaporative cooling on the relationship between aerosols, LH, and precipitation processes. The results show that evaporative cooling is important for cold pool strength and rain enhancement in both cases. However, ice microphysics play a larger role in the midlatitude case compared to the tropics. Detailed analysis of the vertical velocity-governing equation shows that temperature buoyancy can enhance updrafts/downdrafts in the middle/lower troposphere in the convective core region; however, the vertical pressure gradient force (PGF) is of the same order and acts in the opposite direction. Water loading is small but of the same order as the net PGF-temperature buoyancy forcing. The balance among these terms determines the intensity of convection.

  1. Infrasound and Seismic Observation of the Hayabusa Reentry: Burst Signals and Air-to-Ground Coupling Process

    NASA Astrophysics Data System (ADS)

    Ishihara, Y.; Hiramatsu, Y.; Yamamoto, M.; Furumoto, M.; Fujita, K.

    2012-12-01

    The Hayabusa, the world's first sample-return minor body explorer, reentered the Earth's atmosphere on June 13, 2010. This was the third direct reentry event from the interplanetary transfer orbit to the Earth at a velocity of over 11.2 km/s, and was the world's first case of a direct reentry of the spacecraft itself from the interplanetary transfer orbit. This was the very good and rare opportunity to study bolide class meteor phenomena by various aspects. Multi-site ground observations of the Hayabusa reentry were carried out in the Woomera Prohibited Area, Australia (Fujita et al., 2011). The observations were configured with optical imaging, spectroscopies, and shockwave detection with infrasound and seismic sensors. At three main stations (GOS2, GOS2A, and GOS2B), we installed small aperture infrasound/seismic arrays, as well as three single component seismic sub stations (GOS2B-sub1, to GOS2B-sub3) (Yamamoto et al., 2011; Ishihara et al., 2012). The infrasound and seismic sensors clearly recorded sonic-boom-type shockwaves from the Hayabusa sample return capsule (Ishihara et al., 2012). In addition, following capsule signal, lots of signals that probably correspond shockwave from disrupted fragments of spacecraft and energetic bursts of the spacecraft were also recorded (Yamamoto et al., 2011). In this study, we analyze signals generated by hypersonic motion of the disrupted fragments and energetic burst of the spacecraft. In addition, we examine the air-to-ground coupling process by comparing the waveforms computed by finite difference scheme with the actual ones. At all three arrayed main stations, after the capsule's shockwave arrival, we detect multiple shockwave signals by both infrasound and seismic sensors. For some of these signals arrive within 10 seconds after capsule's signal, we can identify one to one correspondence with optically tracked disrupted fragments of the spacecraft. Far after the capsule's signal, we also detect some arrivals of wave

  2. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers.

    PubMed

    Liu, W J; Hu, X L; Ying, L Y; Chen, S Q; Zhang, J Y; Akiyama, H; Cai, Z P; Zhang, B P

    2015-01-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400 nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355 nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355 nm pulsed laser. These were explained by taking into account of the significant heating effect under 355 nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs. PMID:25873327

  3. On the importance of cavity-length and heat dissipation in GaN-based vertical-cavity surface-emitting lasers.

    PubMed

    Liu, W J; Hu, X L; Ying, L Y; Chen, S Q; Zhang, J Y; Akiyama, H; Cai, Z P; Zhang, B P

    2015-01-01

    Cavity-length dependence of the property of optically pumped GaN-based vertical-cavity surface-emitting lasers (VCSELs) with two dielectric distributed Bragg reflectors was investigated. The cavity lengths were well controlled by employing etching with inductively coupled plasma and chemical mechanical polishing. It was found that the lasing characteristics including threshold, slope efficiency and spontaneous emission coupling factor were substantially improved with reducing the cavity length. In comparison with the device pumped by a 400 nm pulsed laser, the lasing spectrum was featured by a red shift and simultaneous broadening with increasing the pumping energy of a 355 nm pulsed laser. Moreover, the lasing threshold was much higher when pumped by a 355 nm pulsed laser. These were explained by taking into account of the significant heating effect under 355 nm pumping. Our results demonstrate that a short cavity length and good heat-dissipation are essential to GaN-based VCSELs.

  4. Oscillatory MHD Convective Flow of Second Order Fluid Through Porous Medium in a Vertical Rotating Channel in Slip-Flow Regime with Heat Radiation

    NASA Astrophysics Data System (ADS)

    Garg, B. P.; Singh, K. D.; Bansal, A. K.

    2015-02-01

    An analysis of an oscillatory magnetohydrodynamic (MHD) convective flow of a second order (viscoelastic), incompressible, and electrically conducting fluid through a porous medium bounded by two infinite vertical parallel porous plates is presented. The two porous plates with slip-flow condition and the no-slip condition are subjected respectively to a constant injection and suction velocity. The pressure gradient in the channel varies periodically with time. A magnetic field of uniform strength is applied in the direction perpendicular to the planes of the plates. The induced magnetic field is neglected due to the assumption of a small magnetic Reynolds number. The temperature of the plate with no-slip condition is non-uniform and oscillates periodically with time and the temperature difference of the two plates is assumed high enough to induce heat radiation. The entire system rotates in unison about the axis perpendicular to the planes of the plates. Adopting complex variable notations, a closed form solution of the problem is obtained. The analytical results are evaluated numerically and then presented graphically to discuss in detail the effects of different parameters of the problem. The velocity, temperature and the skin-friction in terms of its amplitude and phase angle have been shown graphically to observe the effects of the viscoelastic parameter γ, rotation parameter Ω, suction parameter λ , Grashof number Gr, Hartmann number M, the pressure A, Prandtl number Pr, radiation parameter N and the frequency of oscillation ω .

  5. Thermal conductivity of cementitious grouts for geothermal heat pumps. Progress report FY 1997

    SciTech Connect

    Allan, M.L.

    1997-11-01

    Grout is used to seal the annulus between the borehole and heat exchanger loops in vertical geothermal (ground coupled, ground source, GeoExchange) heat pump systems. The grout provides a heat transfer medium between the heat exchanger and surrounding formation, controls groundwater movement and prevents contamination of water supply. Enhanced heat pump coefficient of performance (COP) and reduced up-front loop installation costs can be achieved through optimization of the grout thermal conductivity. The objective of the work reported was to characterize thermal conductivity and other pertinent properties of conventional and filled cementitious grouts. Cost analysis and calculations of the reduction in heat exchanger length that could be achieved with such grouts were performed by the University of Alabama. Two strategies to enhance the thermal conductivity of cementitious grouts were used simultaneously. The first of these was to incorporate high thermal conductivity filler in the grout formulations. Based on previous tests (Allan and Kavanaugh, in preparation), silica sand was selected as a suitable filler. The second strategy was to reduce the water content of the grout mix. By lowering the water/cement ratio, the porosity of the hardened grout is decreased. This results in higher thermal conductivity. Lowering the water/cement ratio also improves such properties as permeability, strength, and durability. The addition of a liquid superplasticizer (high range water reducer) to the grout mixes enabled reduction of water/cement ratio while retaining pumpability. Superplasticizers are commonly used in the concrete and grouting industry to improve rheological properties.

  6. Measured water heating performance of a vertical-bore water-to-water ground source heat pump (WW-GSHP) for domestic water heating over twelve months under simulated occupancy loads

    SciTech Connect

    Ally, Moonis Raza; Munk, Jeffrey D; Baxter, Van D; Gehl, Anthony C

    2014-01-01

    This paper presents monthly performance metrics of a 5.275 kW (1.5 ton) WW-GSHP providing 227 L day-1 domestic hot water at 49 C. Daily water use is simulated as stipulated in the Building America Research Benchmark Definition capturing the living habits of the average U.S household. The 94.5m vertical-bore ground loop is shared with a separate GSHP for space conditioning the 251m2 residential home. Data on entering water temperatures, energy extracted from the ground, delivered energy, compressor electricity use, COP, WW-GSHP run times, and the impact of fan and pump energy consumption on efficiency are presented for each month. Factors influencing performance metrics are highlighted.

  7. THE VERTICAL

    NASA Technical Reports Server (NTRS)

    Albert, Stephen L.; Spencer, Jeffrey B.

    1994-01-01

    'THE VERTICAL' computer keyboard is designed to address critical factors which contribute to Repetitive Motion Injuries (RMI) (including Carpal Tunnel Syndrome) in association with computer keyboard usage. This keyboard splits the standard QWERTY design into two halves and positions each half 90 degrees from the desk. In order to access a computer correctly. 'THE VERTICAL' requires users to position their bodies in optimal alignment with the keyboard. The orthopaedically neutral forearm position (with hands palms-in and thumbs-up) reduces nerve compression in the forearm. The vertically arranged keypad halves ameliorate onset occurrence of keyboard-associated RMI. By utilizing visually-reference mirrored mylar surfaces adjustable to the user's eye, the user is able to readily reference any key indicia (reversed) just as they would on a conventional keyboard. Transverse adjustability substantially reduces cumulative musculoskeletal discomfort in the shoulders. 'THE VERTICAL' eliminates the need for an exterior mouse by offering a convenient finger-accessible curser control while the hands remain in the vertically neutral position. The potential commercial application for 'THE VERTICAL' is enormous since the product can effect every person who uses a computer anywhere in the world. Employers and their insurance carriers are spending hundreds of millions of dollars per year as a result of RMI. This keyboard will reduce the risk.

  8. Recent results from a continuous wave stepped frequency GPR system using a new ground-coupled multi-element antenna array

    NASA Astrophysics Data System (ADS)

    Linford, Neil; Linford, Paul; Payne, Andy

    2016-04-01

    The recent availability of multi-channel GPR instrumentation has allowed high-speed acquisition of densely sampled data sets over unprecedented areas of coverage. Such instrumentation has been of particular interest for the mapping of near-surface archaeological remains where the ability to collect GPR data at very close sample spacings (<0.1m) can provide a unique insight to both image and assess the survival of historic assets at a landscape scale. This paper reviews initial results obtained with a 3d-Radar GeoScope MkIV continuous wave stepped frequency (CWSF) GPR system utilising both initial prototypes and production versions of a newly introduced ground coupled antenna array. Whilst this system originally utilised an air-coupled antenna array there remained some debate over the suitability of an air-coupled antenna for all site conditions, particularly where a conductive surface layer, typical of many archaeological sites in the UK, may impede the transfer of energy into the ground. Encouraging results obtained from an initial prototype ground-coupled antenna array led to the introduction of a full width 22 channel G1922 version in March 2014 for use with the MkIV GeoScope console, offering faster acquisition across a wider frequency bandwidth (60MHz to 3GHz) with a cross-line 0.075m spacing between the individual elements in the array. Field tests over the Roman remains at Silchester corroborated the results from the earlier prototype, demonstrating an increased depth of penetration at the site compared to the previous air-coupled array. Further field tests were conducted with the G1922 over a range of sites, including Roman villa sites, formal post-medieval garden remains and a medieval farmstead to assess the response of the ground-coupled antenna to more challenging site conditions, particularly through water saturated soils. A full production DXG1820 version of the antenna became available for field work in 2015 offering optimisation of the individual

  9. Geothermal direct-heat utilization assistance

    NASA Astrophysics Data System (ADS)

    1993-11-01

    This report consists of brief summaries of the activities of the Geo-Heat Center during the report period. Technical assistance was given to requests from 20 states in the following applications: space and district heating; geothermal heat pumps; greenhouses; aquaculture; industrial plants; electric power; resource/well; equipment; and resort/spa. Research and development activities progressed on compilation of data on low temperature resources and evaluation of groundwater versus ground-coupled heat pumps. Also summarized are technology transfer activities and geothermal progress monitoring activities.

  10. Boiling induced nanoparticle coating and its effect on pool boiling heat transfer on a vertical cylindrical surface using CuO nanofluids

    NASA Astrophysics Data System (ADS)

    Hegde, Ramakrishna N.; Rao, Shrikantha S.; Reddy, R. P.

    2012-09-01

    Experiments were performed to study boiling induced nanoparticle coating and its influence on pool boiling heat transfer using low concentrations of CuO- nanofluid in distilled water at atmospheric pressure. To investigate the effect of the nanoparticle coated surface on pool boiling performance, two different concentrations of CuO nanofluids (0.1 and 0.5 g/l) were chosen and tests were conducted on a clean heater surface in nanofluid and nanoparticle coated surface in pure water. For the bare heater tested in CuO nanofluid, CHF was enhanced by 35.83 and 41.68 % respectively at 0.1 and 0.5 g/l concentration of nanofluid. For the nanoparticle coated heater surface obtained by boiling induced coating using 0.1 and 0.5 g/l concentration of nanofluid and tested in pure water, CHF was enhanced by 29.38 and 37.53 % respectively. Based on the experimental investigations it can be concluded that nanoparticle coating can also be a potential substitute for enhancing the heat transfer in pure water. Transient behaviour of nanofluid was studied by keeping heat flux constant at 1,000 and 1,500 kW/m2 for 90 min in 0.5 g/l concentration. The boiling curve shifted to the right indicating degradation in boiling heat transfer due to prolonged exposure of heater surface to nanofluid. Experimental outcome indicated that pool boiling performance of nanofluid could be a strong function of time and applied heat flux. The longer the duration of exposure of the heater surface, the higher will be the degradation in heat transfer.

  11. Influence of thermophoresis on heat and mass transfer under non-Darcy MHD mixed convection along a vertical flat plate embedded in a porous medium in the presence of radiation

    NASA Astrophysics Data System (ADS)

    Kishan, N.; Jagadha, S.

    2016-01-01

    The paper presents an investigation of the influence of thermophoresis on MHD mixed convective heat and mass transfer of a viscous, incompressible and electrically conducting fluid along a vertical flat plate with radiation effects. The plate is permeable and embedded in a porous medium. To describe the deviation from the Darcy model the Forchheimer flow model is used. The Rosseland approximation is used to describe the radiative heat flux in the energy equation. The governing partial differential equations are transformed into a system of ordinary differential equations using similarity transformation. The nonlinear ordinary differential equations are linearized by using quasilinearization technique and then solved numerically by using implicit finite difference scheme. The numerical results are analyzed for the effects of various physical parameters such as magnetic parameter Ha, mixed convection parameter Ra d /Pe d , Reynolds number Red, radiation parameter R, thermophoretic parameter τ, Prandtl number Pr, and Schmidt number Sc. The heat transfer coefficient is also tabulated for different values of physical parameters.

  12. Thermodynamic analysis of geothermal heat pump during the cold season

    NASA Astrophysics Data System (ADS)

    Dumitrașcu, G.; Dumencu, A.; Horbaniuc, B.; Atanasiu, M. V.

    2016-08-01

    The paper is analysing the performances (COP, power and, heating heat rate function of time) for a ground-coupled heat pump that is used to heat a space during winter, for a period of 180 days. The analysis purpose is to evaluate the time based changes in values of COP and, energy transfers of a geothermal heat pump, considering a scenario for the variation of the ambient temperature in time and an analytical solution for the time dependence of the soil one. The temperatures and the energy transfer rates were determined on the basis of the irreversible entropy balance equation.

  13. Étude numérique de la convection mixte dans une cavité en forme de « T » soumise à un flux de chaleur constant et ventilée par le bas à l'aide d'un jet d'air verticalNumerical study of mixed convection in a ``T'' form cavity submitted to constant heat flux and ventilated from below with a vertical jet

    NASA Astrophysics Data System (ADS)

    Najam, Mostafa; El Alami, Mustapha; Hasnaoui, Mohammed; Amahmid, Abdelkhalk

    A numerical study of the mixed convection is presented in a "T" form cavity, heated with constant heat flux and submitted to a vertical jet of fresh air from below. The heating blocks are identical and the system presents a symmetry with respect to a vertical axis passing by the middle of the openings. The governing equations are solved using the finite difference method. The parameters of control are the Rayleigh number (0⩽Ra⩽10 6), the Reynolds number (1⩽Re⩽1000), the Prandtl number (Pr=0.72), the relative height of the heating blocks ( B= h/ H=0.5), the dimension C of admission and evacuation openings ( C= l/ L=0.15) and the relative distance D between the blocks ( D= d/ L=0.50). The results obtained, with H/ L=1, show the existence of multiple solutions on which the resulting heat transfer depends significantly. To cite this article: M. Najam et al., C. R. Mecanique 330 (2002) 461-467.

  14. Hybrid Heat Pumps Using Selective Water Sorbents (SWS)

    SciTech Connect

    Ally, M. R.

    2006-11-30

    The development of the ground-coupled and air-coupled Heating Ventilation and Air-Conditioning (HVAC) system is essential in meeting the goals of Zero Energy Houses (ZEH), a viable concept vigorously pursued under DOE sponsorship. ORNL has a large Habitat for Humanity complex in Lenoir City where modem buildings technology is incorporated on a continual basis. This house of the future is planned for lower and middle income families in the 21st century. The work undertaken in this CRADA is an integral part of meeting DOE's objectives in the Building America program. SWS technology is a prime candidate for reducing the footprint, cost and improve the performance of ground-coupled heat pumps. The efficacy of this technique to exchange energy with the ground is a topic of immense interest to DOE, builders and HVAC equipment manufacturers. If successful, the SWS concept will become part of a packaged ZEH kit for affordable and high-end houses. Lennox Industries entered into a CRADA with Oak Ridge National Laboratory in November 2004. Lennox, Inc. agreed to explore ways of using Selective Water Sorbent materials to boost the efficiency of air-coupled heat pumps whereas ORNL concentrated on ground-coupled applications. Lennox supplied ORNL with heat exchangers and heat pump equipment for use at ORNL's Habitat for Humanity site in Lenoir City, Tennessee. Lennox is focused upon air-coupled applications of SWS materials at the Product Development and Research Center in Carrollton, TX.

  15. Dissociated Vertical Deviation

    MedlinePlus

    ... Eye Terms Conditions Frequently Asked Questions Español Condiciones Chinese Conditions Dissociated Vertical Deviation En Español Read in Chinese What is Dissociated Vertical Deviation (DVD)? DVD is ...

  16. The Vertical File.

    ERIC Educational Resources Information Center

    Czopek, Vanessa

    The process of establishing the vertical file for a new branch library is traced; suggestions for making the vertical file a better resource are offered; and guidelines covering the general objective, responsibility for selection and maintenance, principles of selection, and scope of the collection for vertical files are presented. A four-item…

  17. Vertical bounce of two vertically aligned balls

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2007-11-01

    When a tennis ball rests on top of a basketball and both drop to the floor together, the tennis ball is projected vertically at high speed. A mass-spring model of the impact, as well as air track data, suggest that the tennis ball should be projected at relatively low speed. Measurements of the forces on each ball and the bounce of vertically aligned superballs are used to resolve the discrepancy.

  18. Vertical axis wind turbine

    SciTech Connect

    Kato, Y.; Seki, K.; Shimizu, Y.

    1981-01-27

    Wind turbines are largely divided into vertical axis wind turbines and propeller (Horizontal axis) wind turbines. The present invention discloses a vertical axis high speed wind turbine provided with a starting and braking control system. This vertical axis wind turbine is formed by having blades of a proper airfoil fitted to respective supporting arms provided radially from a vertical rotary axis by keeping the blade span-wise direction in parallel with the axis and being provided with a low speed control windmill in which the radial position of each operating piece varies with a centrifugal force produced by the rotation of the vertical rotary axis.

  19. Vertical axis wind turbines

    DOEpatents

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  20. Signatures of Currency Vertices

    NASA Astrophysics Data System (ADS)

    Holme, Petter

    2009-03-01

    Many real-world networks have broad degree distributions. For some systems, this means that the functional significance of the vertices is also broadly distributed, in other cases the vertices are equally significant, but in different ways. One example of the latter case is metabolic networks, where the high-degree vertices — the currency metabolites — supply the molecular groups to the low-degree metabolites, and the latter are responsible for the higher-order biological function, of vital importance to the organism. In this paper, we propose a generalization of currency metabolites to currency vertices. We investigate the network structural characteristics of such systems, both in model networks and in some empirical systems. In addition to metabolic networks, we find that a network of music collaborations and a network of e-mail exchange could be described by a division of the vertices into currency vertices and others.

  1. Offset vertical radar profiling

    USGS Publications Warehouse

    Witten, A.; Lane, J.

    2003-01-01

    Diffraction tomography imaging was applied to VRP data acquired by vertically moving a receiving antenna in a number of wells. This procedure simulated a vertical downhole receiver array. Similarly, a transmitting antenna was sequentially moved along a series of radial lines extending outward from the receiver wells. This provided a sequence of multistatic data sets and, from each data set, a two-dimensional vertical cross-sectional image of spatial variations in wave speed was reconstructed.

  2. Vertical Axis Wind Turbine

    2002-04-01

    Blade fatigue life is an important element in determining the economic viability of the Vertical-Axis Wind Turbine (VAWT). VAWT-SAL Vertical Axis Wind Turbine- Stochastic Aerodynamic Loads Ver 3.2 numerically simulates the stochastic (random0 aerodynamic loads of the Vertical-Axis Wind Turbine (VAWT) created by the atomspheric turbulence. The program takes into account the rotor geometry, operating conditions, and assumed turbulence properties.

  3. Vertical two chamber reaction furnace

    DOEpatents

    Blaugher, Richard D.

    1999-03-16

    A vertical two chamber reaction furnace. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium-copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700.degree. and 800.degree. C.) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800.degree. to 950.degree. C. to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product.

  4. Vertical two chamber reaction furnace

    DOEpatents

    Blaugher, R.D.

    1999-03-16

    A vertical two chamber reaction furnace is disclosed. The furnace comprises a lower chamber having an independently operable first heating means for heating the lower chamber and a gas inlet means for admitting a gas to create an ambient atmosphere, and an upper chamber disposed above the lower chamber and having an independently operable second heating means for heating the upper chamber. Disposed between the lower chamber and the upper chamber is a vapor permeable diffusion partition. The upper chamber has a conveyor means for conveying a reactant there through. Of particular importance is the thallinating of long-length thallium-barium-calcium copper oxide (TBCCO) or barium-calcium-copper oxide (BCCO) precursor tapes or wires conveyed through the upper chamber to thereby effectuate the deposition of vaporized thallium (being so vaporized as the first reactant in the lower chamber at a temperature between about 700 and 800 C) on TBCCO or BCCO tape or wire (the second reactant) at its simultaneous annealing temperature in the upper chamber of about 800 to 950 C to thereby replace thallium oxide lost from TBCCO tape or wire because of the high annealing temperature or to deposit thallium on BCCO tape or wire. Continuously moving the tape or wire provides a single-step process that effectuates production of long-length TBCCO superconducting product. 2 figs.

  5. Vertical axis windmill

    SciTech Connect

    Campbell, J.S.

    1980-04-08

    A vertical axis windmill is described which involves a rotatable central vertical shaft having horizontal arms pivotally supporting three sails that are free to function in the wind like the main sail on a sail boat, and means for disabling the sails to allow the windmill to be stopped in a blowing wind.

  6. Geothermal direct-heat utilization assistance. Quarterly project progress report, October--December 1993

    SciTech Connect

    Not Available

    1993-12-31

    This report consists of brief summaries of the activities of the Geo-Heat Center during the report period. Technical assistance was given to requests from 20 states in the following applications: space and district heating; geothermal heat pumps; greenhouses; aquaculture; industrial plants; electric power; resource/well; equipment; and resort/spa. Research and development activities progressed on (1) compilation of data on low-temperature resources and (2) evaluation of groundwater vs. ground-coupled heat pumps. Also summarized are technology transfer activities and geothermal progress monitoring activities.

  7. Heat transfer system

    DOEpatents

    McGuire, Joseph C.

    1982-01-01

    A heat transfer system for a nuclear reactor. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  8. Heat transfer system

    DOEpatents

    Not Available

    1980-03-07

    A heat transfer system for a nuclear reactor is described. Heat transfer is accomplished within a sealed vapor chamber which is substantially evacuated prior to use. A heat transfer medium, which is liquid at the design operating temperatures, transfers heat from tubes interposed in the reactor primary loop to spaced tubes connected to a steam line for power generation purposes. Heat transfer is accomplished by a two-phase liquid-vapor-liquid process as used in heat pipes. Condensible gases are removed from the vapor chamber through a vertical extension in open communication with the chamber interior.

  9. Methods of testing parameterizations: Vertical ocean mixing

    NASA Technical Reports Server (NTRS)

    Tziperman, Eli

    1992-01-01

    The ocean's velocity field is characterized by an exceptional variety of scales. While the small-scale oceanic turbulence responsible for the vertical mixing in the ocean is of scales a few centimeters and smaller, the oceanic general circulation is characterized by horizontal scales of thousands of kilometers. In oceanic general circulation models that are typically run today, the vertical structure of the ocean is represented by a few tens of discrete grid points. Such models cannot explicitly model the small-scale mixing processes, and must, therefore, find ways to parameterize them in terms of the larger-scale fields. Finding a parameterization that is both reliable and plausible to use in ocean models is not a simple task. Vertical mixing in the ocean is the combined result of many complex processes, and, in fact, mixing is one of the less known and less understood aspects of the oceanic circulation. In present models of the oceanic circulation, the many complex processes responsible for vertical mixing are often parameterized in an oversimplified manner. Yet, finding an adequate parameterization of vertical ocean mixing is crucial to the successful application of ocean models to climate studies. The results of general circulation models for quantities that are of particular interest to climate studies, such as the meridional heat flux carried by the ocean, are quite sensitive to the strength of the vertical mixing. We try to examine the difficulties in choosing an appropriate vertical mixing parameterization, and the methods that are available for validating different parameterizations by comparing model results to oceanographic data. First, some of the physical processes responsible for vertically mixing the ocean are briefly mentioned, and some possible approaches to the parameterization of these processes in oceanographic general circulation models are described in the following section. We then discuss the role of the vertical mixing in the physics of the

  10. Derivation of vertical air velocity from conventional Radiosonde ascents

    NASA Astrophysics Data System (ADS)

    Manguttathil Gopalakrishnan, Manoj; Mohanakumar, Kesavapillai; Samson, Titu; Kottayil, Ajil; Varadarajan, Rakesh; Rebello, Rejoy

    2016-07-01

    In this work, we devise a method to estimate air vertical velocity from ascending radiosondes similar to that described in published results, but with certain differences in deriving the balloon parameters and the drag coefficient, while not considering explicitly the heat exchange between the balloon and the environment. We basically decompose the observed balloon ascent rate into vertical velocity in still air due to buoyancy force and that due to vertical air motion. The first part is computed from basic hydrodynamical principles and the vertical velocity is derived as the difference between observed ascent rate and the estimated still air vertical velocity. The derived values agree reasonably well (r=0.66) with vertical velocities observed with a collocated wind profiler radar, and the sources of uncertainties are discussed. Since vertical velocity is a difficult quantity to measure directly without expensive methods, derivation of the same from the conventional radiosonde ascents could be of great importance to the meteorological communities.

  11. Vertical diffusivity of the Western Arctic Ocean halocline

    NASA Astrophysics Data System (ADS)

    Shaw, William J.; Stanton, Timothy P.

    2014-08-01

    A nearly year-long series of upper ocean temperature, conductivity, and temperature microstructure profiles were collected from an ice camp drifting in the Beaufort Gyre as part of the 1997-1998 Surface Heat Budget of the Arctic Experiment (SHEBA). Geographically, the record includes portions over the deep Canada Basin and the steep bathymetry of the Chukchi Borderlands region. Hydrographically, the record includes "cool," Pacific-origin haloclines, which contain a variety of subsurface temperature maxima, and cold haloclines typical of the Eurasian Basins. We present estimates of the vertical turbulent diffusivity derived from the dissipation rate of thermal variance and calculations of the associated vertical heat fluxes. We find that vertical diffusion proceeds at molecular rates in the deep basins and away from topographic features. While still relatively small, diffusivity is enhanced by 1 order of magnitude near and above the Chukchi Borderlands. The enhanced diffusivity is correlated to an increase in water column strain variance above the Borderlands, providing a linkage between bathymetry, internal wave activity and turbulence. The Chukchi Borderlands play a significant role in heat transport in the Western Arctic. They are a pathway for horizontal heat transport and a hot spot for vertical heat transport. Vertical fluxes make a substantial contribution to the energy balance of the sea ice cover in this region. Heat fluxes between the halocline and underlying Atlantic Water are shown to be small and lacking vertical connection near surface waters.

  12. Micromachined electrostatic vertical actuator

    DOEpatents

    Lee, Abraham P.; Sommargren, Gary E.; McConaghy, Charles F.; Krulevitch, Peter A.

    1999-10-19

    A micromachined vertical actuator utilizing a levitational force, such as in electrostatic comb drives, provides vertical actuation that is relatively linear in actuation for control, and can be readily combined with parallel plate capacitive position sensing for position control. The micromachined electrostatic vertical actuator provides accurate movement in the sub-micron to micron ranges which is desirable in the phase modulation instrument, such as optical phase shifting. For example, compact, inexpensive, and position controllable micromirrors utilizing an electrostatic vertical actuator can replace the large, expensive, and difficult-to-maintain piezoelectric actuators. A thirty pound piezoelectric actuator with corner cube reflectors, as utilized in a phase shifting diffraction interferometer can be replaced with a micromirror and a lens. For any very precise and small amplitudes of motion` micromachined electrostatic actuation may be used because it is the most compact in size, with low power consumption and has more straightforward sensing and control options.

  13. The effects of soil vertical discretization, soil thermal properties, and soil heat convection by liquid water transfer on the water and energy cycles in a coupled land-atmosphere model

    NASA Astrophysics Data System (ADS)

    Wang, Fuxing; Dufresne, Jean-Louis; Chéruy, Frédérique; Ducharne, Agnès

    2015-04-01

    The soil heat transfer is an important component in general circulation model (GCM), and accurate representation of subsurface thermodynamics is essential for earth system modeling. The accuracy of the soil thermodynamics simulation is affected by many factors: (1) the bottom boundary layer position used in numerical scheme; (2) the soil thermal property (heat capacity and thermal conductivity) parameterization; as well as (3) the physical processes considered in the model. However, the impact of their correct representation on the quality of the simulated climate is poorly documented, and the way state-of-the art land surface model (LSM) used for climate simulations account for them is highly variable. For instance bottom boundary layer position varies from 2 m to 10 m or even more (100 m), the parameterizations of the soil thermal properties not always account for the soil texture effects, and the soil heat convection process is neglected in most soil thermodynamics models. In this work, we revisited the soil thermodynamics model included in the ORCHIDEE LSM in order (1) to determine the soil bottom layer depth which allows for simulating the annual cycle of temperature; (2) to improve the parameterization of the soil thermal properties (thermal conductivity and heat capacity) by accounting for both soil moisture and soil texture effects on the soil thermal properties; (3) to take into account the heat generated by liquid water movement in soil thermodynamics. The developpement of the parameterizations has been done in a 1-D framework where the results of the Finite Difference Method have been compared to the analytical solution. Sensitivity experiments with the LMDZ-ORCHIDEE coupled model (atmosphere-land component of IPSL-CM model) have been then designed to evaluate the impact of the soil thermal properties and soil heat convection on the water and energy cycles of the land-atmosphere. Main results are: (1) the 8 meter soil depth is proposed as a minimum

  14. Thermal Impacts of Vertical Greenery Systems

    NASA Astrophysics Data System (ADS)

    Safikhani, Tabassom; Abdullah, Aminatuzuhariah Megat; Ossen, Dilshan Remaz; Baharvand, Mohammad

    2014-12-01

    - Using vertical greenery systems to reduce heat transmission is becoming more common in modern architecture. Vertical greenery systems are divided into two main categories; green facades and living walls. This study aims to examine the thermal performance of vertical greenery systems in hot and humid climates. An experimental procedure was used to measure indoor temperature and humidity. These parameters were also measured for the gap between the vertical greenery systems and wall surfaces. Three boxes were used as small-scale rooms. Two boxes were provided with either a living wall or a green facade and one box did not have any greenery (benchmark). Blue Trumpet Vine was used in the vertical greenery systems. The data were recorded over the course of three sunny days in April 2013. An analyses of the results showed that the living wall and green facade reduced indoor temperature up to 4.0 °C and 3.0 °C, respectively. The living wall and green facade also reduced cavity temperatures by 8.0 °C and 6.5 °C, respectively.

  15. Vertical shaft windmill

    NASA Technical Reports Server (NTRS)

    Grana, D. C.; Inge, S. V., Jr. (Inventor)

    1983-01-01

    A vertical shaft has several equally spaced blades mounted. Each blade consists of an inboard section and an outboard section skew hinged to the inboard section. The inboard sections automatically adjust their positions with respect to the fixed inboard sections with changes in velocity of the wind. This windmill design automatically governs the maximum rotational speed of shaft.

  16. Vertical axis windmill

    SciTech Connect

    Zheug, Y.K.

    1984-03-06

    A vertical axis windmill has a blade pivotally connected to a rotatable support structure on an axis passing through its center of gravity which is arranged to lie forward of its aerodynamic center whereby the blade automatically swings outwardly and inwardly when moving on the windward and leeward sides respectively of the axis of rotation of said support means.

  17. Vertical shaft windmill

    SciTech Connect

    Grana, D.C.; Inge, S.V. Jr.

    1983-11-15

    A vertical shaft has several equally spaced blades mounted thereon. Each blade consists of an inboard section and an outboard section skew hinged to the inboard section. The inboard sections automatically adjust their positions with respect to the fixed inboard sections with changes in velocity of the wind. This windmill design automatically governs the maximum rotational speed of shaft.

  18. Aiding Vertical Guidance Understanding

    NASA Technical Reports Server (NTRS)

    Feary, Michael; McCrobie, Daniel; Alkin, Martin; Sherry, Lance; Polson, Peter; Palmer, Everett; McQuinn, Noreen

    1998-01-01

    A two-part study was conducted to evaluate modern flight deck automation and interfaces. In the first part, a survey was performed to validate the existence of automation surprises with current pilots. Results indicated that pilots were often surprised by the behavior of the automation. There were several surprises that were reported more frequently than others. An experimental study was then performed to evaluate (1) the reduction of automation surprises through training specifically for the vertical guidance logic, and (2) a new display that describes the flight guidance in terms of aircraft behaviors instead of control modes. The study was performed in a simulator that was used to run a complete flight with actual airline pilots. Three groups were used to evaluate the guidance display and training. In the training, condition, participants went through a training program for vertical guidance before flying the simulation. In the display condition, participants ran through the same training program and then flew the experimental scenario with the new Guidance-Flight Mode Annunciator (G-FMA). Results showed improved pilot performance when given training specifically for the vertical guidance logic and greater improvements when given the training and the new G-FMA. Using actual behavior of the avionics to design pilot training and FMA is feasible, and when the automated vertical guidance mode of the Flight Management System is engaged, the display of the guidance mode and targets yields improved pilot performance.

  19. On the vertical structure of damped steady circulation in the tropics

    NASA Technical Reports Server (NTRS)

    Geisler, J. E.; Stevens, D. E.

    1982-01-01

    This paper presents an analysis of the vertical structure of steady motion in a dissipative tropical atmosphere forced by steady isolated diabatic heating. Vertical modes appropriate to the problem are obtained, and the forcing is projected onto these modes. With the use of an analytic expression obtained by Gill (1980) for the horizontal structure, these modes are summed to obtain the amplitude and the vertical structure of the response in the region to the east of the heating.

  20. Jamming in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; Steel, Fiona

    2011-03-01

    We study jamming of low aspect-ratio cylindrical Delrin grains in a vertical channel. Grain heights are less than their diameter so the grains resemble antacid tablets, coins, or poker chips. These grains are allowed to fall through a vertical channel with a square cross section where the channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. Grains are sometimes observed to form jams, stable structures supported by the channel walls with no support beneath them. The probability of jam occurrence and the strength or robustness of a jam is effected by grain and channel sizes. We will present experimental measurements of the jamming probability and jam strength in this system and discuss the relationship of these results to other experiments and theories. Supported by an Undergraduate Research Grant from Penn State Erie, The Behrend College.

  1. Jamming in Vertical Channels

    NASA Astrophysics Data System (ADS)

    Baxter, G. William; McCausland, Jeffrey; Steel, Fiona

    2010-03-01

    We experimentally study jamming of cylindrical grains in a vertical channel. The grains have a low aspect-ratio (height/diameter < 1) so their shape is like antacid tablets or poker chips. They are allowed to fall through a vertical channel with a square cross section. The channel width is greater than the diameter of a grain and constant throughout the length of the channel with no obstructions or constrictions. It is observed that grains sometimes jam in this apparatus. In a jam, grains form a stable structure from one side of the channel to the other with nothing beneath them. Jams may be strong enough to support additional grains above. The probability of a jam occurring is a function of the grain height and diameter. We will present experimental measurements of the jamming probability in this system and discuss the relationship of these results to other experiments and theories.

  2. Vertical velocity-CCN correlations

    NASA Astrophysics Data System (ADS)

    Hudson, J. G.; Noble, S. R.

    2013-12-01

    The realization that smaller cloud droplets evaporate more readily (Xue and Feingold 2006; Jiang et al. 2002) gives rise to an anti-indirect aerosol effect (IAE); less cloudiness with pollution. The greater latent heat exchange of the greater evaporation in more polluted clouds adds TKE and buoyancy gradients that can enhance vertical velocity (W), mixing and entrainment (Zhao and Austin 2005). Stronger W can increase horizontal motions, which can further enhance droplet evaporation, which further enhances latent heat exchange and vertical motions, thus, positive feedback. This could also include latent heat released during condensation (Lee and Feingold 2010), which is more rapid for the greater surface areas of the smaller more numerous droplets. These theories imply a positive relationship between within-cloud W variations; i.e., standard deviation of W (σw) and CCN concentration (NCCN) rather than W and NCCN. This implies greater turbulence in polluted clouds, which could possibly counteract the reduction of cloudiness of anti-IAE. During two stratus cloud projects, 50 cloud penetrations in 9 MASE flights and 34 cloud penetrations in 13 POST flights, within-cloud σw-NCCN showed correlation coefficients (R) of 0.50 and 0.39. Panel a shows similar within-cloud σw-NCCN R in all altitude bands for 17 RICO flights in small cumulus clouds. R for W-NCCN showed similar values but only at low altitudes. Out-of-cloud σw-NCCN showed similar high values except at the highest altitudes. Within-cloud σw showed higher R than within-cloud W with droplet concentrations (Nc), especially at higher altitudes. Panel b for 13 ICE-T cumulus cloud flights in the same location as RICO but during the opposite season, however, showed σw and W uncorrelated with NCCN at all altitudes; and W and σw correlated with Nc only at the highest altitudes. On the other hand, out-of-cloud σw was correlated with NCCN at all altitudes with R similar to the corresponding R of the other projects

  3. Vortex Formation in Vertically Stratified Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Stewart, Glen R.

    2013-10-01

    A central problem of planet formation is how to form large planetesimals in a turbulent protoplanetary disk. Recent work suggests that MRI turbulence would excite such large velocities that the planetesimals would collisionally fragment rather than grow. The structure of chondritic meteorites indicates a gentle nebular environment where chondrules are sorted by size and cemented together rapidly. Although it is well established that anticyclones can concentrate particles that are weakly coupled to the gas in protoplanetary disks, the conditions required for the formation and long-time stability of anticyclones in a vertically stratified disk are still highly uncertain. Fully three dimensional fluid dynamic simulations of protoplanetary disks are computationally expensive when one requires a computational domain that is large compared to the vertical scale height of the disk. An alternative simulation approach is to use potential temperature as the vertical coordinate so that the equations of motion resemble the shallow water equations (Dowling et al. 1998). We have therefore modified a multilayer shallow water simulation code to model the formation of vortices in a vertically stratified protoplanetary disk with a radial entropy gradient. Vertical stratification of the disk is modeled by using multiple layers, where each layer has a different constant value of the entropy. By forcing a slope in the interfaces between the layers, we impose a radial entropy gradient in the disk. Radiative heating and cooling causes vertical mass exchange between adjacent constant entropy layers according to a Newton cooling formula. We find that the formation of anticyclones is robust, and that these vortices actively excite density waves, which in turn, transport angular momentum through the disk. Our simulations therefore yield new insights on how the dusty dead zones of protoplanetary disks can transport angular momentum through the disk by purely hydrodynamic processes. Support

  4. Solar heating system

    SciTech Connect

    Larkin, W.J.

    1984-01-31

    A solar heating system is provided incorporating the flat plate collector and storage tanks substantially in the same unit and avoiding the usual reverse-siphon problems that are inherent in the nature of a passive integral system of this type by a piping system wherein heating and elevation of certain vertical components of connecting piping reverses, or almost reverses, the usual net pressure head which is responsible for creating the reverse siphon.

  5. 'Endurance' Untouched (vertical)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This navigation camera mosaic, created from images taken by NASA's Mars Exploration Rover Opportunity on sols 115 and 116 (May 21 and 22, 2004) provides a dramatic view of 'Endurance Crater.' The rover engineering team carefully plotted the safest path into the football field-sized crater, eventually easing the rover down the slopes around sol 130 (June 12, 2004). To the upper left of the crater sits the rover's protective heatshield, which sheltered Opportunity as it passed through the martian atmosphere. The 360-degree view is presented in a vertical projection, with geometric and radiometric seam correction.

  6. Vertical combustor for particulate refuse

    NASA Astrophysics Data System (ADS)

    Chung, P. M.; Carlson, L.

    1981-03-01

    A one-dimensional model is constructed of a vertical combustor for refuse particle combustion in order to analyze it for waste energy recovery. The three components of the model, fuel particles, inert solid particles and the gaseous mixture are described by momentum, energy, and mass conservation equations, resulting in three different flow velocities and temperatures for the medium. The gaseous component is further divided into six chemical species that evolve in combustion at temperatures below about 1367 K. A detailed description is given of the fuel particle combustion through heating, devolatilization, and combustion of the volatile gas in the boundary layer, return of the flame sheet to the fuel surface, and char combustion. The solutions show the combustor to be viable for U.S. refuse which consists of combustibles that can be volatilized up to 85 to 95% below 1366 K. Char combustion, however, is found to be too slow to be attempted in the combustor, where the fuel residence time is of the order of 2 s.

  7. Heat-pipe Earth.

    PubMed

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics. PMID:24067709

  8. Heat-pipe Earth.

    PubMed

    Moore, William B; Webb, A Alexander G

    2013-09-26

    The heat transport and lithospheric dynamics of early Earth are currently explained by plate tectonic and vertical tectonic models, but these do not offer a global synthesis consistent with the geologic record. Here we use numerical simulations and comparison with the geologic record to explore a heat-pipe model in which volcanism dominates surface heat transport. These simulations indicate that a cold and thick lithosphere developed as a result of frequent volcanic eruptions that advected surface materials downwards. Declining heat sources over time led to an abrupt transition to plate tectonics. Consistent with model predictions, the geologic record shows rapid volcanic resurfacing, contractional deformation, a low geothermal gradient across the bulk of the lithosphere and a rapid decrease in heat-pipe volcanism after initiation of plate tectonics. The heat-pipe Earth model therefore offers a coherent geodynamic framework in which to explore the evolution of our planet before the onset of plate tectonics.

  9. Vertical wind turbine

    SciTech Connect

    Danson, D.P.

    1988-08-16

    This patent describes a wind driven turbine of the vertical axis type comprising: (a) a support base; (b) a generally vertical column rotatably mounted to the support base; (c) upper and lower support means respectively mounted on the column for rotation therewith; wind driven blades connected between the upper and lower support means for rotation about the column and each blade being individually rotatable about a blade axis extending longitudinally through the blade to vary a blade angle of attach thereof relative to wind velocity during rotation about the column; and (e) control means for variably adjusting angles of attack of each blade to incident wind, the control means including a connecting rod means having drive means for rotating each blade about the associated blade axis in response to radial movement of the connecting rod means and control shaft pivotally mounted within the column and having a first shaft portion connected to the connecting rod means and a second shaft portion radially offset from the first shaft portion and pivotally connected to radially displace the first portion and thereby the connecting rod means to vary the blade angles of attack during rotation about the column.

  10. Abyssal recipes revisited: A new physically-based approach to quantify the vertical diapycnal diffusion profile required to balance water masses formation by surface heat and freshwater fluxes with error bars.

    NASA Astrophysics Data System (ADS)

    Hochet, Antoine; Tailleux, Rémi; Kuhlbrodt, Till; Ferreira, David; Gregory, Jonathan

    2016-04-01

    We revisit the calculation of the diapycnal mixing required to equilibrate the formation of deep water made by Munk and Wunsch 1998 (MW). Our calculation is made possible by a new physically-based density variable, called thermodynamic neutral density, recently introduced by Tailleux 2016, which accurately approximates Jackett and McDougall 1997 empirical neutral density. Unlike neutral density, however, thermodynamic neutral density is a materially conserved variable. As a result, it can only change as the result of diabatic molecular diffusive effects by heat and salt, and is therefore more suitable for studying ocean mixing than neutral density, since the latter can also change as the result of non-material effects unrelated to mixing processes. Climatological temperature and salinity data are used along with heat and freshwater surface fluxes to estimate the dianeutral mean fluxes using a framework stemming from Walin 1982 ideas. The mean fluxes values are estimated to range between 0.2e-4 m^2/s and 5e-4 m^2/s for the densest waters and between 0.025e-4 m^2/s and 0.1e-4 m^2/s for middepth and surface waters. These values contrasts with the previous values of 1e-4 m^2/s first obtained by Munk 1966 and then by MW, and appear much closer to observational estimates of diapycnal mixing obtained by tracer release or microstructure measurements. We further show that the range of uncertainty in the above values is due to the nonlinearities of the equation of state for density.

  11. Heat pipe array heat exchanger

    DOEpatents

    Reimann, Robert C.

    1987-08-25

    A heat pipe arrangement for exchanging heat between two different temperature fluids. The heat pipe arrangement is in a ounterflow relationship to increase the efficiency of the coupling of the heat from a heat source to a heat sink.

  12. Analytic solution for vertical launch into orbit

    NASA Technical Reports Server (NTRS)

    Boltz, Frederick W.

    1989-01-01

    An approximate analytic solution is presented for the motion and heating of nonlifting spacecraft launched vertically for ascending flight through the atmosphere into earth orbit. The solution is based on Chapman's Z-function transformation of the equations of motion with the assumption of an exponential atmosphere. The transformed equations have been modified to include the effects of thrusting with mass loss. It is assumed that the vehicle negotiates a gravity turn during ascent so that the thrust vector is aligned in the flight-path direction. Numerical results are presented to document the analytic solution and provide evidence of the useful information generated by it.

  13. Multicolored Vertical Silicon Nanowires

    SciTech Connect

    Seo, Kwanyong; Wober, Munib; Steinvurzel, P.; Schonbrun, E.; Dan, Yaping; Ellenbogen, T.; Crozier, K. B.

    2011-04-13

    We demonstrate that vertical silicon nanowires take on a surprising variety of colors covering the entire visible spectrum, in marked contrast to the gray color of bulk silicon. This effect is readily observable by bright-field microscopy, or even to the naked eye. The reflection spectra of the nanowires each show a dip whose position depends on the nanowire radii. We compare the experimental data to the results of finite difference time domain simulations to elucidate the physical mechanisms behind the phenomena we observe. The nanowires are fabricated as arrays, but the vivid colors arise not from scattering or diffractive effects of the array, but from the guided mode properties of the individual nanowires. Each nanowire can thus define its own color, allowing for complex spatial patterning. We anticipate that the color filter effect we demonstrate could be employed in nanoscale image sensor devices.

  14. Direct Observation of Ultralow Vertical Emittance using a Vertical Undulator

    SciTech Connect

    Wootton, Kent

    2015-09-17

    In recent work, the first quantitative measurements of electron beam vertical emittance using a vertical undulator were presented, with particular emphasis given to ultralow vertical emittances [K. P. Wootton, et al., Phys. Rev. ST Accel. Beams, 17, 112802 (2014)]. Using this apparatus, a geometric vertical emittance of 0.9 #6;± 0.3 pm rad has been observed. A critical analysis is given of measurement approaches that were attempted, with particular emphasis on systematic and statistical uncertainties. The method used is explained, compared to other techniques and the applicability of these results to other scenarios discussed.

  15. Observation of Picometer Vertical Emittance with a Vertical Undulator

    NASA Astrophysics Data System (ADS)

    Wootton, K. P.; Boland, M. J.; Dowd, R.; Tan, Y.-R. E.; Cowie, B. C. C.; Papaphilippou, Y.; Taylor, G. N.; Rassool, R. P.

    2012-11-01

    Using a vertical undulator, picometer vertical electron beam emittances have been observed at the Australian Synchrotron storage ring. An APPLE-II type undulator was phased to produce a horizontal magnetic field, which creates a synchrotron radiation field that is very sensitive to the vertical electron beam emittance. The measured ratios of undulator spectral peak heights are evaluated by fitting to simulations of the apparatus. With this apparatus immediately available at most existing electron and positron storage rings, we find this to be an appropriate and novel vertical emittance diagnostic.

  16. Geothermal Heat Transfer

    SciTech Connect

    Basmajian, V.V.

    1986-01-28

    This patent describes a heat transfer apparatus which consists of: heat exchanging means for orientation in the earth below ground substantially vertically, having a hollow conduit of length from top to bottom much greater than the span across the hollow conduit orthogonal to its length with a top, bottom and an intermediate portion contiguous and communicating with the top and bottom portions for allowing thermally conductive fluid to flow freely between the top, intermediate and bottom portions for immersion in thermally conductive fluid in the region around the heat exchanging means for increasing the heat flow between the latter and earth when inserted into a substantially vertical borehole in the earth with the top portion above the bottom portion. The heat exchanger consists of heat exchanging conduit means in the intermediate portion for carrying refrigerant. The heat exchanging conduit consisting of tubes of thermally conductive material for carrying the refrigerant and extending along the length of the hollow conduit for a tube length that is less than the length of the hollow conduit. The hollow conduit is formed with port means between the top and the plurality of tubes for allowing the thermally conductive fluid to pass in a flow path embracing the tubes, the bottom portion, an outer channel around the hollow conduit and the port means.

  17. Heating with waste heat

    SciTech Connect

    Beabout, R.W.

    1986-09-02

    Most of the power consumed in the gaseous diffusion process is converted into heat of compression, which is removed from the process gas and rejected into the atmosphere by recirculating cooling water over cooling towers. The water being handled through the X-333 and X-330 Process Buildings can be heated to 140 to 150/sup 0/F for heating use. The Gas Centrifuge Enrichment Plant is provided with a recirculating heating water (RHW) system which uses X-330 water and wasted heat. The RHW flow is diagrammed. (DLC)

  18. ON-LINE TOOLS FOR PROPER VERTICAL POSITIONING OF VERTICAL SAMPLING INTERVALS DURING SITE ASSESSMENT

    EPA Science Inventory

    This presentation presents on-line tools for proper vertical positioning of vertical sampling intervals during site assessment. Proper vertical sample interval selection is critical for generate data on the vertical distribution of contamination. Without vertical delineation, th...

  19. Heat exchanger with auxiliary cooling system

    DOEpatents

    Coleman, John H.

    1980-01-01

    A heat exchanger with an auxiliary cooling system capable of cooling a nuclear reactor should the normal cooling mechanism become inoperable. A cooling coil is disposed around vertical heat transfer tubes that carry secondary coolant therethrough and is located in a downward flow of primary coolant that passes in heat transfer relationship with both the cooling coil and the vertical heat transfer tubes. A third coolant is pumped through the cooling coil which absorbs heat from the primary coolant which increases the downward flow of the primary coolant thereby increasing the natural circulation of the primary coolant through the nuclear reactor.

  20. 4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    4. VIEW OF VERTICAL BORING MACHINE. (Bullard) Vertical turning lathe (VTL). Machining the fixture for GE Turboshroud. G.S. O'Brien, operator. - Juniata Shops, Machine Shop No. 1, East of Fourth Avenue at Third Street, Altoona, Blair County, PA

  1. Comparative Calculation of Heat Exchange with the Ground in Residential Building Including Periodes of Heat Waves

    NASA Astrophysics Data System (ADS)

    Staszczuk, Anna; Kuczyński, Tadeusz; Wojciech, Magdalena; Ziembicki, Piotr

    2016-06-01

    The paper provides verification of 3D transient ground-coupled model to calculation of heat exchange between ground and typical one-storey, passive residential building. The model was performed with computer software WUFI®plus and carried out to estimate the indoor air temperatures during extending hot weather periods. For verifying the results of calculations performed by the WUFI®plus software, the most recent version of EnergyPlus software version was used. Comparison analysis of calculation results obtained with the two above mentioned calculation method was made for two scenarios of slab on ground constructions: without thermal insulation and with thermal insulation under the whole slab area. Comprehensive statistical analysis was done including time series analysis and descriptive statistics parameters.

  2. Latitude and longitude vertical disparities.

    PubMed

    Read, Jenny C A; Phillipson, Graeme P; Glennerster, Andrew

    2009-12-09

    The literature on vertical disparity is complicated by the fact that several different definitions of the term "vertical disparity" are in common use, often without a clear statement about which is intended or a widespread appreciation of the properties of the different definitions. Here, we examine two definitions of retinal vertical disparity: elevation-latitude and elevation-longitude disparities. Near the fixation point, these definitions become equivalent, but in general, they have quite different dependences on object distance and binocular eye posture, which have not previously been spelt out. We present analytical approximations for each type of vertical disparity, valid for more general conditions than previous derivations in the literature: we do not restrict ourselves to objects near the fixation point or near the plane of regard, and we allow for non-zero torsion, cyclovergence, and vertical misalignments of the eyes. We use these expressions to derive estimates of the latitude and longitude vertical disparities expected at each point in the visual field, averaged over all natural viewing. Finally, we present analytical expressions showing how binocular eye position-gaze direction, convergence, torsion, cyclovergence, and vertical misalignment-can be derived from the vertical disparity field and its derivatives at the fovea.

  3. The Gains from Vertical Scaling

    ERIC Educational Resources Information Center

    Briggs, Derek C.; Domingue, Ben

    2013-01-01

    It is often assumed that a vertical scale is necessary when value-added models depend upon the gain scores of students across two or more points in time. This article examines the conditions under which the scale transformations associated with the vertical scaling process would be expected to have a significant impact on normative interpretations…

  4. Scale Shrinkage in Vertical Equating.

    ERIC Educational Resources Information Center

    Camilli, Gregory; And Others

    1993-01-01

    Three potential causes of scale shrinkage (measurement error, restriction of range, and multidimensionality) in item response theory vertical equating are discussed, and a more comprehensive model-based approach to establishing vertical scales is described. Test data from the National Assessment of Educational Progress are used to illustrate the…

  5. Application of burst vibrothermography to characterize planar vertical cracks

    NASA Astrophysics Data System (ADS)

    Mendioroz, Arantza; Celorrio, Ricardo; Cifuentes, Ángel; Zatón, Lander; Salazar, Agustín.

    2016-05-01

    We present a method to characterize vertical cracks in a fast way using burst vibrothermography. In this technique the sample is excited by ultrasounds and, at the defect, rubbing of the contacting surfaces produces heat that can be detected as a temperature rise at the surface using an infrared camera. In this work, first we present the solution of the direct problem, i.e., the calculation of the surface temperature distribution produced by a vertical heat source representing a crack excited by an ultrasound burst, and we choose the information that will be used to characterize the crack, namely, one thermogram and one timing-graph. Next we address the inverse problem, consisting of finding the heat source distribution that is responsible for the observed surface temperature. This inverse problem is ill-posed, and a naïve inversion process is unstable. We propose to use three penalty terms, based on zero order Tikhonov and Total Variation functionals and the Lasso method, to stabilize the inversion. By inverting synthetic data, we analyze the performance of the algorithm as a function of the depth of the heat source and we study the effect of the burst duration and noise level in the data on the quality of the reconstructions. Finally, we invert experimental data taken in samples containing calibrated heat sources. The results show that it is possible to characterize vertical cracks down to depths of 6 mm in AISI 304 stainless steel.

  6. Research and Development on Heat Pumps for Space Conditioning Applications: Proceedings of the DOE/ORNL Heat Pump Conference

    NASA Astrophysics Data System (ADS)

    Jacobs, V. A.; Powell, R. H., Jr.

    1985-08-01

    This conference was planned to provide information on current activities in the US Department of Energy (DOE) and Oak Ridge National Laboratory (ORNL) Building Equipment Research (BER) Program. It was primarily for the benefit of HVAC equipment manufacturers and other interested parties, including utilities, independent research and development organizations, universities, other government groups, and research funding and management organizations. The technical presentations were grouped into two principal subject areas: electric systems and thermally activated systems. Electric-system topics included field performance studies, laboratory experiments on cycling performance, analytical estimates of the benefits of variable capacity and zone control, nonazeotropic refrigerant mixtures, ground-coupled systems, and an analysis of Stirling-cycle heat pumps. In the area of thermally activated heat pumps, presentations centered on the development of absorption systems, Stirling-engine-driven systems, and a linear, free-piston IC-engine compressor. Separate abstracts have been prepared for 27 presentations for inclusion in the Energy Data Base.

  7. Vertical bloch line memory

    NASA Technical Reports Server (NTRS)

    Katti, R.; Wu, J.; Stadler, H.

    1990-01-01

    Vertical Bloch Line (VBL) memory is a recently conceived, integrated, solid-state, block-access, VLSI memory which offers the potential of 1Gbit/sq cm real storage density, gigabit per second data rates, and sub-millisecond average access times simultaneously at relatively low mass, volume, and power values when compared to alternative technologies. VBL's are micromagnetic structures within magnetic domain walls which can be manipulated using magnetic fields from integrated conductors. The presence or absence of VBL pairs are used to store binary information. At present, efforts are being directed at developing a single-chip memory using 25Mbit/sq cm technology in magnetic garnet material which integrates, at a single operating point, the writing, storage, reading, and amplification functions needed in a memory. This paper describes the current design architecture, functional elements, and supercomputer simulation results which are used to assist the design process. The current design architecture uses three metal layers, two ion implantation steps for modulating the thickness of the magnetic layer, one ion implantation step for assisting propagation in the major line track, one NiFe soft magnetic layer, one CoPt hard magnetic layer, and one reflective Cr layer for facilitating magneto-optic observation of magnetic structure. Data are stored in a series of elongated magnetic domains, called stripes, which serve as storage sites for arrays of VBL pairs. The ends of these stripes are placed near conductors which serve as VBL read/write gates. A major line track is present to provide a source and propagation path for magnetic bubbles. Writing and reading, respectively, are achieved by converting magnetic bubbles to VBL's and vice versa. The output function is effected by stretching a magnetic bubble and detecting it magnetoresistively. Experimental results from the past design cycle created four design goals for the current design cycle. First, the bias field ranges

  8. Ground-source Heat Pumps Applied to Commercial Buildings

    SciTech Connect

    Parker, Steven A.; Hadley, Donald L.

    2009-07-14

    Ground-source heat pumps can provide an energy-efficient, cost-effective way to heat and cool commercial facilities. While ground-source heat pumps are well established in the residential sector, their application in larger, commercial-style, facilities is lagging, in part because of a lack of experience with the technology by those in decision-making positions. Through the use of a ground-coupling system, a conventional water-source heat pump design is transformed to a unique means of utilizing thermodynamic properties of earth and groundwater for efficient operation throughout the year in most climates. In essence, the ground (or groundwater) serves as a heat source during winter operation and a heat sink for summer cooling. Many varieties in design are available, so the technology can be adapted to almost any site. Ground-source heat pump systems can be used widely in commercial-building applications and, with proper installation, offer great potential for the commercial sector, where increased efficiency and reduced heating and cooling costs are important. Ground-source heat pump systems require less refrigerant than conventional air-source heat pumps or air-conditioning systems, with the exception of direct-expansion-type ground-source heat pump systems. This chapter provides information and procedures that an energy manager can use to evaluate most ground-source heat pump applications. Ground-source heat pump operation, system types, design variations, energy savings, and other benefits are explained. Guidelines are provided for appropriate application and installation. Two case studies are presented to give the reader a sense of the actual costs and energy savings. A list of manufacturers and references for further reading are included for prospective users who have specific or highly technical questions not fully addressed in this chapter. Sample case spreadsheets are provided in Appendix A. Additional appendixes provide other information on the ground

  9. Wood burning space heating stove

    SciTech Connect

    Bane, J.H.

    1981-08-04

    The design of a space heating wood burning stove, formed as a rectangular fire box, having a plurality of horizontal flue ducts leading to a flue manifold, adapted to generate substantial vertical convection currents of air, and further including vertical fins to enhance said convection currents, and further including a plurality of draft valves in substantial alignment with respective ones of said flue ducts for efficient burning of wood within said fire box is presented. Assembly of the fire box of the stove is completed under stressed conditions to prevent warping of the fire box panels from heating and cooling cycles.

  10. Vertical axis wind turbine airfoil

    DOEpatents

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

    2012-12-18

    A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

  11. Visualize Vertical Connectedness (Middle Ground).

    ERIC Educational Resources Information Center

    van Allen, Lanny

    1996-01-01

    Discusses the possibility of vertical connectedness in K-12 education through references to journal articles and the author's own reflections. Suggests that middle school teachers may be leaders in a movement toward eliminating redundancy and gaps between grade levels. (TB)

  12. Vertically scanned laser sheet microscopy.

    PubMed

    Dong, Di; Arranz, Alicia; Zhu, Shouping; Yang, Yujie; Shi, Liangliang; Wang, Jun; Shen, Chen; Tian, Jie; Ripoll, Jorge

    2014-01-01

    Laser sheet microscopy is a widely used imaging technique for imaging the three-dimensional distribution of a fluorescence signal in fixed tissue or small organisms. In laser sheet microscopy, the stripe artifacts caused by high absorption or high scattering structures are very common, greatly affecting image quality. To solve this problem, we report here a two-step procedure which consists of continuously acquiring laser sheet images while vertically displacing the sample, and then using the variational stationary noise remover (VSNR) method to further reduce the remaining stripes. Images from a cleared murine colon acquired with a vertical scan are compared with common stitching procedures demonstrating that vertically scanned light sheet microscopy greatly improves the performance of current light sheet microscopy approaches without the need for complex changes to the imaging setup and allows imaging of elongated samples, extending the field of view in the vertical direction.

  13. Horizontal and Vertical Line Designs.

    ERIC Educational Resources Information Center

    Johns, Pat

    2003-01-01

    Presents an art lesson in which students learn about the artist Piet Mondrian and create their own abstract artworks. Focuses on geometric shapes using horizontal and vertical lines. Includes background information about the artist. (CMK)

  14. Heating stove

    SciTech Connect

    Darnell, E.

    1980-10-28

    A heating stove has a fire box composed of first and second pluralities of parallel aligned connected vertically oriented curved open-ended conduits. The lower extremities of the conduits of said first and second pluralities being aligned for contacting a common planar surface to support the stove, with the fire box further being formed by generally planar front and back plates, of substantially the same size and shape, with the front plate having an inlet port therethrough and the back plate having an exhaust port therein. The conduit central portions are largely within the stove fire box. A baffle within the fire box promotes three-pass flow of hot air across the conduit surfaces within the fire box. The first and second pluralities of curved conduits are opposed and in interdigitated engagement. Curved strips separate the curved conduits and thus facilitate stove construction with the conduits in interdigitated engagement. A closing mechanism for the stove door operates with caming action to assure that the door, when closed, is tightly fastened so that the hot coals cannot escape. In another embodiment, the fire box is cylindrical , formed by two curved side plates and two generally planar end plates, and the curved conduits pass through the fire box.

  15. Vertical profiles of BC direct radiative effect over Italy: high vertical resolution data and atmospheric feedbacks

    NASA Astrophysics Data System (ADS)

    Močnik, Griša; Ferrero, Luca; Castelli, Mariapina; Ferrini, Barbara S.; Moscatelli, Marco; Grazia Perrone, Maria; Sangiorgi, Giorgia; Rovelli, Grazia; D'Angelo, Luca; Moroni, Beatrice; Scardazza, Francesco; Bolzacchini, Ezio; Petitta, Marcello; Cappelletti, David

    2016-04-01

    Black carbon (BC), and its vertical distribution, affects the climate. Global measurements of BC vertical profiles are lacking to support climate change research. To fill this gap, a campaign was conducted over three Italian basin valleys, Terni Valley (Appennines), Po Valley and Passiria Valley (Alps), to characterize the impact of BC on the radiative budget under similar orographic conditions. 120 vertical profiles were measured in winter 2010. The BC vertical profiles, together with aerosol size distribution, aerosol chemistry and meteorological parameters, have been determined using a tethered balloon-based platform equipped with: a micro-Aethalometer AE51 (Magee Scientific), a 1.107 Grimm OPC (0.25-32 μm, 31 size classes), a cascade impactor (Siuotas SKC), and a meteorological station (LSI-Lastem). The aerosol chemical composition was determined from collected PM2.5 samples. The aerosol absorption along the vertical profiles was measured and optical properties calculated using the Mie theory applied to the aerosol size distribution. The aerosol optical properties were validated with AERONET data and then used as inputs to the radiative transfer model libRadtran. Vertical profiles of the aerosol direct radiative effect, the related atmospheric absorption and the heating rate were calculated. Vertical profile measurements revealed some common behaviors over the studied basin valleys. From below the mixing height to above it, a marked concentration drop was found for both BC (from -48.4±5.3% up to -69.1±5.5%) and aerosol number concentration (from -23.9±4.3% up to -46.5±7.3%). These features reflected on the optical properties of the aerosol. Absorption and scattering coefficients decreased from below the MH to above it (babs from -47.6±2.5% up to -71.3±3.0% and bsca from -23.5±0.8% up to -61.2±3.1%, respectively). Consequently, the Single Scattering Albedo increased above the MH (from +4.9±2.2% to +7.4±1.0%). The highest aerosol absorption was

  16. Flow reversal of fully developed double diffusive mixed convection in a vertical channel

    NASA Astrophysics Data System (ADS)

    Makhatar, Nur Asiah Mohd; Saleh, Habibis; Hashim, Ishak

    2015-10-01

    The mixed convection flow within a vertical channel having internal heat generation at a rate proportional to a power of the temperature difference is considered. The analysis is concerning the studies of occurrence of flow reversal and the effects of three dimensionless parameters, identified as the internal heat parameter (G), a mixed convection parameter (λ) and the exponent (p) in the local heating term on the fully developed double diffusive mixed convection flow in a vertical channel. The governing equations are solved numerically via MAPLE. It was found that flow reversal occurs with larger values of internal heat parameter and mixed convection parameter, but smaller values of local-heating exponent. They also show that, unlike the internal heat parameter and the local-heating exponent, the mixed convection parameter do not give any significant effect on the temperature.

  17. Heat accumulator

    SciTech Connect

    Bracht, A.

    1981-09-29

    A heat accumulator comprises a thermally-insulated reservoir full of paraffin wax mixture or other flowable or meltable heat storage mass, heat-exchangers immersed in the mass, a heat-trap connected to one of the heat-exchangers, and a heat user connected to the other heat-exchanger. Pumps circulate fluids through the heat-trap and the heat-using means and the respective heat-exchangers, and a stirrer agitates and circulates the mass, and the pumps and the stirrer and electric motors driving these devices are all immersed in the mass.

  18. Vertical structure of recent Arctic warming.

    PubMed

    Graversen, Rune G; Mauritsen, Thorsten; Tjernström, Michael; Källén, Erland; Svensson, Gunilla

    2008-01-01

    Near-surface warming in the Arctic has been almost twice as large as the global average over recent decades-a phenomenon that is known as the 'Arctic amplification'. The underlying causes of this temperature amplification remain uncertain. The reduction in snow and ice cover that has occurred over recent decades may have played a role. Climate model experiments indicate that when global temperature rises, Arctic snow and ice cover retreats, causing excessive polar warming. Reduction of the snow and ice cover causes albedo changes, and increased refreezing of sea ice during the cold season and decreases in sea-ice thickness both increase heat flux from the ocean to the atmosphere. Changes in oceanic and atmospheric circulation, as well as cloud cover, have also been proposed to cause Arctic temperature amplification. Here we examine the vertical structure of temperature change in the Arctic during the late twentieth century using reanalysis data. We find evidence for temperature amplification well above the surface. Snow and ice feedbacks cannot be the main cause of the warming aloft during the greater part of the year, because these feedbacks are expected to primarily affect temperatures in the lowermost part of the atmosphere, resulting in a pattern of warming that we only observe in spring. A significant proportion of the observed temperature amplification must therefore be explained by mechanisms that induce warming above the lowermost part of the atmosphere. We regress the Arctic temperature field on the atmospheric energy transport into the Arctic and find that, in the summer half-year, a significant proportion of the vertical structure of warming can be explained by changes in this variable. We conclude that changes in atmospheric heat transport may be an important cause of the recent Arctic temperature amplification.

  19. Schlieren visualization of water natural convection in a vertical ribbed channel

    NASA Astrophysics Data System (ADS)

    Fossa, M.; Misale, M.; Tanda, G.

    2015-11-01

    Schlieren techniques are valuable tools for the qualitative and quantitative visualizations of flows in a wide range of scientific and engineering disciplines. A large number of schlieren systems have been developed and documented in the literature; majority of applications involve flows of gases, typically air. In this work, a schlieren technique is applied to visualize the buoyancy-induced flow inside vertical ribbed channels using water as convective fluid. The test section consists of a vertical plate made of two thin sheets of chrome-plated copper with a foil heater sandwiched between them; the external sides of the plate are roughened with transverse, square-cross-sectioned ribs. Two parallel vertical walls, smooth and unheated, form with the heated ribbed plate two adjacent, identical and asymmetrically heated, vertical channels. Results include flow schlieren visualizations with colour-band filters, reconstructions of the local heat transfer coefficient distributions along the ribbed surfaces and comparisons with past experiments performed using air as working fluid.

  20. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, P.R.; McLennan, G.A.

    1984-08-30

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  1. Fast reactor power plant design having heat pipe heat exchanger

    DOEpatents

    Huebotter, Paul R.; McLennan, George A.

    1985-01-01

    The invention relates to a pool-type fission reactor power plant design having a reactor vessel containing a primary coolant (such as liquid sodium), and a steam expansion device powered by a pressurized water/steam coolant system. Heat pipe means are disposed between the primary and water coolants to complete the heat transfer therebetween. The heat pipes are vertically oriented, penetrating the reactor deck and being directly submerged in the primary coolant. A U-tube or line passes through each heat pipe, extended over most of the length of the heat pipe and having its walls spaced from but closely proximate to and generally facing the surrounding walls of the heat pipe. The water/steam coolant loop includes each U-tube and the steam expansion device. A heat transfer medium (such as mercury) fills each of the heat pipes. The thermal energy from the primary coolant is transferred to the water coolant by isothermal evaporation-condensation of the heat transfer medium between the heat pipe and U-tube walls, the heat transfer medium moving within the heat pipe primarily transversely between these walls.

  2. Convective flows in enclosures with vertical temperature or concentration gradients

    NASA Technical Reports Server (NTRS)

    Wang, L. W.; Chai, A. T.; Sun, D. J.

    1988-01-01

    The transport process in the fluid phase during the growth of a crystal has a profound influence on the structure and quality of the solid phase. In vertical growth techniques the fluid phase is often subjected to vertical temperature and concentration gradients. The main objective is to obtain more experimental data on convective flows in enclosures with vertical temperature or concentration gradients. Among actual crystal systems the parameters vary widely. The parametric ranges studied for mass transfer are mainly dictated by the electrochemical system employed to impose concentration gradients. Temperature or concentration difference are maintained between two horizontal end walls. The other walls are kept insulated. Experimental measurements and observations were made of the heat transfer or mass transfer, flow patterns, and the mean and fluctuating temperature distribution. The method used to visualize the flow pattern in the thermal cases is an electrochemical pH-indicator method. Laser shadowgraphs are employed to visualize flow patterns in the solutal cases.

  3. Heat Without Heat

    NASA Astrophysics Data System (ADS)

    Lubkin, Elihu

    1997-04-01

    Logic of the Second Law of Thermodynamics demands acquisition of naked entropy. Accordingly, the leanest liaison between systems is not a diathermic membrane, it is a purely informational tickler, leaking no appreciable energy. The subsystem here is a thermodynamic universe, which gets `heated' entropically, yet without gaining calories. Quantum Mechanics graciously supports that(Lubkin, E. and Lubkin, T., International Journal of Theoretical Physics,32), 933-943 (1993) (at a cost of about 1 bit) through entanglement---across this least permeable of membranes---with what is beyond that universe. Heat without heat(Also v. forthcoming Proceedings of the 4th Drexel University Conference of September 1994) is the aspirin for Boltzmann's headache, conserving entropy in mechanical isolation, even while increasing entropy in thermodynamic isolation.

  4. Rewetting of hot vertical rod during jet impingement surface cooling

    NASA Astrophysics Data System (ADS)

    Agrawal, Chitranjan; Kumar, Ravi; Gupta, Akhilesh; Chatterjee, Barun

    2016-06-01

    A stainless steel (SS-316) vertical rod of 12 mm diameter at 800 ± 10 °C initial temperature was cooled by normal impinging round water jet. The surface rewetting phenomenon was investigated for a range of jet diameter 2.5-4.8 mm and jet Reynolds number 5000-24,000 using a straight tube type nozzle. The investigation were made from the stagnation point to maximum 40 mm downstream locations, simultaneously for both upside and downside directions. The cooling performance of the vertical rod was evaluated on the basis of rewetting parameters i.e. rewetting temperature, wetting delay, rewetting velocity and the maximum surface heat flux. Two separate Correlations have been proposed for the dimensionless rewetting velocity in terms of rewetting number and the maximum surface heat flux that predicts the experimental data within an error band of ±20 and ±15 % respectively.

  5. Vertical and Interfacial Transport in Wetlands (Invited)

    NASA Astrophysics Data System (ADS)

    Variano, E. A.

    2010-12-01

    The objective of this work is to understand the fluxes connecting the water column, substrate, and atmosphere in wetland environments. To do this, analytical, numerical, and laboratory models have been used to quantify the hydrodynamic contributions to vertical fluxes. A key question is whether the hydrodynamic transport can be modeled as a diffusivity, and, if so, what the vertical structure of this diffusivity is. This question will be addressed in a number of flow types and for a number of fluxes. The fluxes of interest are heat, sediment, dissolved gases (such as methane and oxygen) and other dissolved solutes (such as nutrients and pollutants). The flows of interest include: unidirectional current, reversing flow (under waves, seiches, and tides), wind-sheared surface flows, and thermal convection. Rain and bioturbation can be important, but are not considered in the modeling work discussed herein. Specifically, we will present results on gas transport at wind-sheared free surface, sediment transport in unidirectional flow, and heat transfer in an oscillating flow cause by a seiche. All three of these will be used to consider the question of appropriate analytical models for vertical transport. The analytic models considered here are all 1D models that assume homogeneity in the horizontal plane. The numerical models use finite element methods and resolve the flow around individual vegetation stems in an idealized geometry. Laboratory models discussed herein also use an idealized geometry. Vegetation is represented by an array of cylinders, whose geometry is modeled after Scirpus spp. wetlands in Northern California. The laboratory model is constructed in a way that allows optical access to the flow, even in dense vegetation and far from boundaries. This is accomplished by using fluoropolymer plastics to construct vegetation models. The optical access allows us to employ particle image velocimetry (PIV) and planar laser induced fluorescence (PLIF) to measure

  6. Vertical motion simulator familiarization guide

    NASA Technical Reports Server (NTRS)

    Danek, George L.

    1993-01-01

    The Vertical Motion Simulator Familiarization Guide provides a synoptic description of the Vertical Motion Simulator (VMS) and descriptions of the various simulation components and systems. The intended audience is the community of scientists and engineers who employ the VMS for research and development. The concept of a research simulator system is introduced and the building block nature of the VMS is emphasized. Individual sections describe all the hardware elements in terms of general properties and capabilities. Also included are an example of a typical VMS simulation which graphically illustrates the composition of the system and shows the signal flow among the elements and a glossary of specialized terms, abbreviations, and acronyms.

  7. Measurements of vertical bar Vcb vertical bar and vertical bar Vub vertical bar at BaBar

    SciTech Connect

    Rotondo, M.

    2005-10-12

    We report results from the BABAR Collaboration on the semileptonic B decays, highlighting the measurements of the magnitude of the Cabibbo-Kobayashi-Maskawa matrix elements Vub and Vcb. We describe the techniques used to obtain the matrix element |Vcb| using the measurement of the inclusive B {yields} Xclv process and a large sample of exclusive B {yields} D*lv decays. The vertical bar Vub vertical bar matrix elements has been measured studying different kinematic variables of the B {yields} Xulv process, and also with the exclusive reconstruction of B {yields} {pi}({rho})lv decays.

  8. Vertical feed stick wood fuel burning furnace system

    DOEpatents

    Hill, Richard C.

    1982-01-01

    A stove or furnace for efficient combustion of wood fuel includes a vertical feed combustion chamber (15) for receiving and supporting wood fuel in a vertical attitude or stack. A major upper portion of the combustion chamber column comprises a water jacket (14) for coupling to a source of water or heat transfer fluid for convection circulation of the fluid. The locus (31) of wood fuel combustion is thereby confined to the refractory base of the combustion chamber. A flue gas propagation delay channel (34) extending laterally from the base of the chamber affords delayed travel time in a high temperature refractory environment sufficient to assure substantially complete combustion of the gaseous products of wood burning with forced air prior to extraction of heat in heat exchanger (16). Induced draft draws the fuel gas and air mixture laterally through the combustion chamber and refractory high temperature zone to the heat exchanger and flue. Also included are active sources of forced air and induced draft, multiple circuit couplings for the recovered heat, and construction features in the refractory material substructure and metal component superstructure.

  9. Free convection over a vertical porous plate with transpiration

    NASA Technical Reports Server (NTRS)

    Parikh, P. G.; Moffat, R. J.; Kays, W. M.; Bershader, D.

    1974-01-01

    The problem of free convection over an isothermal vertical porous plate with transpiration is studied both numerically and experimentally. Numerical solutions to the variable-property transpired free-convection boundary layer equations have been obtained using the finite difference procedure of Patankar and Spalding (1967). The effects of uniform transpiration on heat transfer and on temperature and velocity profiles are predicted. Interferometrically measured nondimensional temperature profiles for the uniform wall temperature and transpiration case agreed closely with these numerical predictions.

  10. A generalized correlation for condensation on vertical fluted surfaces

    SciTech Connect

    Panchal, C.B.

    1996-03-01

    A correlation was developed for laminar film condensation on vertical fluted surfaces. The theoretical analysis of Panchal and Bell was used for defining important physical property groups. The experimental data of Combs et al. were used to validate the proposed correlation. The experimental database used in the present study included four flute geometries that could be approximated to cosine type flutes and seven fluids. The resulting correlation can predict the average condensate heat-transfer coefficient within {plus_minus} 20%.

  11. Kinematic and diabatic vertical velocity climatologies from a chemistry climate model

    NASA Astrophysics Data System (ADS)

    Marinke Hoppe, Charlotte; Ploeger, Felix; Konopka, Paul; Müller, Rolf

    2016-05-01

    The representation of vertical velocity in chemistry climate models is a key element for the representation of the large-scale Brewer-Dobson circulation in the stratosphere. Here, we diagnose and compare the kinematic and diabatic vertical velocities in the ECHAM/Modular Earth Submodel System (MESSy) Atmospheric Chemistry (EMAC) model. The calculation of kinematic vertical velocity is based on the continuity equation, whereas diabatic vertical velocity is computed using diabatic heating rates. Annual and monthly zonal mean climatologies of vertical velocity from a 10-year simulation are provided for both kinematic and diabatic vertical velocity representations. In general, both vertical velocity patterns show the main features of the stratospheric circulation, namely, upwelling at low latitudes and downwelling at high latitudes. The main difference in the vertical velocity pattern is a more uniform structure for diabatic and a noisier structure for kinematic vertical velocity. Diabatic vertical velocities show higher absolute values both in the upwelling branch in the inner tropics and in the downwelling regions in the polar vortices. Further, there is a latitudinal shift of the tropical upwelling branch in boreal summer between the two vertical velocity representations with the tropical upwelling region in the diabatic representation shifted southward compared to the kinematic case. Furthermore, we present mean age of air climatologies from two transport schemes in EMAC using these different vertical velocities and analyze the impact of residual circulation and mixing processes on the age of air. The age of air distributions show a hemispheric difference pattern in the stratosphere with younger air in the Southern Hemisphere and older air in the Northern Hemisphere using the transport scheme with diabatic vertical velocities. Further, the age of air climatology from the transport scheme using diabatic vertical velocities shows a younger mean age of air in the

  12. Physics and the Vertical Jump

    ERIC Educational Resources Information Center

    Offenbacher, Elmer L.

    1970-01-01

    The physics of vertical jumping is described as an interesting illustration for motivating students in a general physics course to master the kinematics and dynamics of one dimensional motion. The author suggests that mastery of the physical principles of the jump may promote understanding of certain biological phenomena, aspects of physical…

  13. Vertical Sextants give Good Sights

    NASA Astrophysics Data System (ADS)

    Dixon, Mark

    Many texts stress the need for marine sextants to be held precisely vertical at the instant that the altitude of a heavenly body is measured. Several authors lay particular emphasis on the technique of the instrument in a small arc about the horizontal axis to obtain a good sight. Nobody, to the author's knowledge, however, has attempted to quantify the errors involved, so as to compare them with other errors inherent in determining celestial position lines. This paper sets out to address these issues and to pose the question: what level of accuracy of vertical alignment can reasonably be expected during marine sextant work at sea ?When a heavenly body is brought to tangency with the visible horizon it is particularly important to ensure that the sextant is held in a truly vertical position. To this end the instrument is rocked gently about the horizontal so that the image of the body describes a small arc in the observer's field of vision. As Bruce Bauer points out, tangency with the horizon must be achieved during the process of rocking and not a second or so after rocking has been discontinued. The altitude is recorded for the instant that the body kisses the visible horizon at the lowest point of the rocking arc, as in Fig. 2. The only other visual clue as to whether the sextant is vertical is provided by the right angle made by the vertical edge of the horizon glass mirror with the horizon. There may also be some input from the observer's sense of balance and his hand orientation.

  14. Graphene vertical hot-electron terahertz detectors

    SciTech Connect

    Ryzhii, V.; Satou, A.; Otsuji, T.; Ryzhii, M.; Mitin, V.; Shur, M. S.

    2014-09-21

    We propose and analyze the concept of the vertical hot-electron terahertz (THz) graphene-layer detectors (GLDs) based on the double-GL and multiple-GL structures with the barrier layers made of materials with a moderate conduction band off-set (such as tungsten disulfide and related materials). The operation of these detectors is enabled by the thermionic emissions from the GLs enhanced by the electrons heated by incoming THz radiation. Hence, these detectors are the hot-electron bolometric detectors. The electron heating is primarily associated with the intraband absorption (the Drude absorption). In the frame of the developed model, we calculate the responsivity and detectivity as functions of the photon energy, GL doping, and the applied voltage for the GLDs with different number of GLs. The detectors based on the cascade multiple-GL structures can exhibit a substantial photoelectric gain resulting in the elevated responsivity and detectivity. The advantages of the THz detectors under consideration are associated with their high sensitivity to the normal incident radiation and efficient operation at room temperature at the low end of the THz frequency range. Such GLDs with a metal grating, supporting the excitation of plasma oscillations in the GL-structures by the incident THz radiation, can exhibit a strong resonant response at the frequencies of several THz (in the range, where the operation of the conventional detectors based on A{sub 3}B{sub 5} materials, in particular, THz quantum-well detectors, is hindered due to a strong optical phonon radiation absorption in such materials). We also evaluate the characteristics of GLDs in the mid- and far-infrared ranges where the electron heating is due to the interband absorption in GLs.

  15. Mechanisms of Ocean Heat Uptake

    NASA Astrophysics Data System (ADS)

    Garuba, Oluwayemi

    An important parameter for the climate response to increased greenhouse gases or other radiative forcing is the speed at which heat anomalies propagate downward in the ocean. Ocean heat uptake occurs through passive advection/diffusion of surface heat anomalies and through the redistribution of existing temperature gradients due to circulation changes. Atlantic meridional overturning circulation (AMOC) weakens in a warming climate and this should slow the downward heat advection (compared to a case in which the circulation is unchanged). However, weakening AMOC also causes a deep warming through the redistributive effect, thus increasing the downward rate of heat propagation compared to unchanging circulation. Total heat uptake depends on the combined effect of these two mechanisms. Passive tracers in a perturbed CO2 quadrupling experiments are used to investigate the effect of passive advection and redistribution of temperature anomalies. A new passive tracer formulation is used to separate ocean heat uptake into contributions due to redistribution and passive advection-diffusion of surface heating during an ocean model experiment with abrupt increase in surface temperature. The spatial pattern and mechanisms of each component are examined. With further experiments, the effects of surface wind, salinity and temperature changes in changing circulation and the resulting effect on redistribution in the individual basins are isolated. Analysis of the passive advection and propagation path of the tracer show that the Southern ocean dominates heat uptake, largely through vertical and horizontal diffusion. Vertical diffusion transports the tracer across isopycnals down to about 1000m in 100 years in the Southern ocean. Advection is more important in the subtropical cells and in the Atlantic high latitudes, both with a short time scale of about 20 years. The shallow subtropical cells transport the tracer down to about 500m along isopycnal surfaces, below this vertical

  16. Tropical Cyclone Intensity in Vertical Wind Shear.

    NASA Astrophysics Data System (ADS)

    Wong, Martin L. M.; Chan, Johnny C. L.

    2004-08-01

    the midlevel center to rotate about the surface center is also observed. These results support the idea that the resistance to vertical tilt by the mutual rotation between the low-level and midlevel centers is also valid in the moist simulations.It is hypothesized that the secondary circulation and the associated diabatic heating reduce the vertical tilt and the weakening. Condensation heating offsets the anomalous cooling effect due to the anomalous rising motion ahead of the vortex tilt. For small VWS, the vertical motion asymmetry is not strong enough to destroy the complete secondary circulation and the eyewall. As a result, a large temperature asymmetry and the associated vortex tilt cannot develop. Furthermore, there is no entrainment of cool/dry air in the upper troposphere. Therefore, TCs under small shears can be as intense as the CTRL.Large-scale asymmetries in the form of anticyclones found in previous studies are also observed. These asymmetries are apparently related to the change of shears near the TCs. While the shears at outer radii stay roughly constant with time, the shears near the TC centers can have large temporal fluctuations both in magnitude and orientation. This result suggests that the location at which the VWS is estimated in observational studies could be important in determining the relationship between VWS and TC intensity change.


  17. Vertically Integrated Circuits at Fermilab

    SciTech Connect

    Deptuch, Grzegorz; Demarteau, Marcel; Hoff, James; Lipton, Ronald; Shenai, Alpana; Trimpl, Marcel; Yarema, Raymond; Zimmerman, Tom; /Fermilab

    2009-01-01

    The exploration of the vertically integrated circuits, also commonly known as 3D-IC technology, for applications in radiation detection started at Fermilab in 2006. This paper examines the opportunities that vertical integration offers by looking at various 3D designs that have been completed by Fermilab. The emphasis is on opportunities that are presented by through silicon vias (TSV), wafer and circuit thinning and finally fusion bonding techniques to replace conventional bump bonding. Early work by Fermilab has led to an international consortium for the development of 3D-IC circuits for High Energy Physics. The consortium has submitted over 25 different designs for the Fermilab organized MPW run organized for the first time.

  18. Kinematic Fitting of Detached Vertices

    SciTech Connect

    Mattione, Paul

    2007-05-01

    The eg3 experiment at the Jefferson Lab CLAS detector aims to determine the existence of the $\\Xi_{5}$ pentaquarks and investigate the excited $\\Xi$ states. Specifically, the exotic $\\Xi_{5}^{--}$ pentaquark will be sought by first reconstructing the $\\Xi^{-}$ particle through its weak decays, $\\Xi^{-}\\to\\pi^{-}\\Lambda$ and $\\Lambda\\to\\pi^{-}$. A kinematic fitting routine was developed to reconstruct the detached vertices of these decays, where confidence level cuts on the fits are used to remove background events. Prior to fitting these decays, the exclusive reaction $\\gamma D\\rightarrow pp\\pi^{-}$ was studied in order to correct the track measurements and covariance matrices of the charged particles. The $\\Lambda\\rightarrow p\\pi^{-}$ and $\\Xi^{-}\\to\\pi^{-}\\Lambda$ decays were then investigated to demonstrate that the kinematic fitting routine reconstructs the decaying particles and their detached vertices correctly.

  19. Carbothermic reduction with parallel heat sources

    DOEpatents

    Troup, Robert L.; Stevenson, David T.

    1984-12-04

    Disclosed are apparatus and method of carbothermic direct reduction for producing an aluminum alloy from a raw material mix including aluminum oxide, silicon oxide, and carbon wherein parallel heat sources are provided by a combustion heat source and by an electrical heat source at essentially the same position in the reactor, e.g., such as at the same horizontal level in the path of a gravity-fed moving bed in a vertical reactor. The present invention includes providing at least 79% of the heat energy required in the process by the electrical heat source.

  20. Next generation vertical electrode cells

    NASA Astrophysics Data System (ADS)

    Brown, Craig

    2001-05-01

    The concept of the vertical electrode cell (VEC) for aluminum electrowinning is presented with reference to current research. Low-temperature electrolysis allows nonconsumable metal-alloy anodes to show ongoing promise in laboratory tests. The economic and environmental advantages of the VEC are surveyed. The unique challenges of bringing VEC technology into practice are discussed. The current status of laboratory research is summarized. New results presented show that commercial purity aluminum can be produced with promisingly high current efficiency.

  1. NASA-Ames vertical gun

    NASA Technical Reports Server (NTRS)

    Schultz, P. H.

    1984-01-01

    A national facility, the NASA-Ames vertical gun range (AVGR) has an excellent reputation for revealing fundamental aspects of impact cratering that provide important constraints for planetary processes. The current logistics in accessing the AVGR, some of the past and ongoing experimental programs and their relevance, and the future role of this facility in planetary studies are reviewed. Publications resulting from experiments with the gun (1979 to 1984) are listed as well as the researchers and subjects studied.

  2. Thermosyphon boiling in vertical channels

    NASA Astrophysics Data System (ADS)

    Bar-Cohen, A.; Schweitzer, H.

    The thermal characteristics of ebullient cooling systems for VHSIC and VLSI microelectronic component thermal control are studied by experimentally and analytically investigating boiling heat transfer from a pair of flat, closely spaced, isoflux plates immersed in saturated water. A theoretical model for liquid flow rate through the channel is developed and used as a basis for correlating the rate of heat transfer from the channel walls. Experimental results for wall temperature as a function of axial location, heat flux, and plate spacing are presented. The finding that the wall superheat at constant imposed heat flux decreases as the channel is narrowed is explained with the aid of a boiling thermosiphon analysis which yields the mass flux through the channel.

  3. Boiling heat transfer of refrigerant R-21 in upward flow in plate-fin heat exchanger

    NASA Astrophysics Data System (ADS)

    Kuznetsov, V. V.; Shamirzaev, A. S.

    2015-11-01

    The article presents the results of experimental investigation of boiling heat transfer of refrigerant R-21 in upward flow in a vertical plate-fin heat exchanger with transverse size of the channels that is smaller than the capillary constant. The heat transfer coefficients obtained in ranges of small mass velocities and low heat fluxes, which are typical of the industry, have been poorly studied yet. The characteristic patterns of the upward liquid-vapor flow in the heat exchanger channels and the regions of their existence are detected. The obtained data show a weak dependence of heat transfer coefficient on equilibrium vapor quality, mass flow rate, and heat flux density and do not correspond to calculations by the known heat transfer models. A possible reason for this behavior is a decisive influence of evaporation of thin liquid films on the heat transfer at low heat flux.

  4. [Vertical fractures: apropos of 2 clinical cases].

    PubMed

    Félix Mañes Ferrer, J; Micò Muñoz, P; Sánchez Cortés, J L; Paricio Martín, J J; Miñana Laliga, R

    1991-01-01

    The aim of the study is to present a clinical review of the vertical root fractures. Two clinical cases are presented to demonstrates the criteria for obtaining a correct diagnosis of vertical root fractures.

  5. Vertical separation of the two beams

    SciTech Connect

    Heifets, S.

    1985-10-01

    The author discusses the problem of design of insertion points on the SSC, and in particular keeping the length necessary for them under control. Here he considers the possibility of having vertically separated beams, without a vertical dispersion suppressor.

  6. Vertical Feature Mask Feature Classification Flag Extraction

    Atmospheric Science Data Center

    2013-03-28

      Vertical Feature Mask Feature Classification Flag Extraction This routine demonstrates extraction of the ... in a CALIPSO Lidar Level 2 Vertical Feature Mask feature classification flag value. It is written in Interactive Data Language (IDL) ...

  7. [Vertical fractures: apropos of 2 clinical cases].

    PubMed

    Félix Mañes Ferrer, J; Micò Muñoz, P; Sánchez Cortés, J L; Paricio Martín, J J; Miñana Laliga, R

    1991-01-01

    The aim of the study is to present a clinical review of the vertical root fractures. Two clinical cases are presented to demonstrates the criteria for obtaining a correct diagnosis of vertical root fractures. PMID:1659859

  8. Laboratory scale simulation of spontaneous vertical convective vortex generation

    NASA Astrophysics Data System (ADS)

    Sharifulin, Albert; Poludnitsin, Anatoly

    2009-11-01

    The new mechanism of spontaneous vertical vortex generation in stratified fluid is under consideration. This phenomenon was discovered in the framework of experimental attempt [1] to proof the hypothesis of universal character of bifurcation curve formulated in [2]. The experiment with slow cubic cell inclination from bottom heating position was performed. The theoretically predicted curve form had been proved; but in the transition process from abnormal convection flow to normal one during bifurcation curve crossing the unexpected spontaneous vertical convective vortex motion has been discovered. Possibility of spontaneous vertical convective vortex generation application to atmospheric behavior explanation and to Earth's mantle one is discussed. New non-local hurricane generation mechanism and observed oceanic volcano archipelago's form explanation attempt are formulated and speculated. [1] AN Sharifulin, AN Poludnitsin, AS Kravchuk Laboratory Scale Simulation of Nonlocal Generation of a Tropical Cyclone. Journal of Experimental and Theoretical Physics, 2008, V.107, No.6, p.1090. [2] AI Nikitin, AN Sharifulin, Concerning the bifurcations of steady-state thermal convection regimes in a closed cavity due to the Whitney folding-type singularity. Heat Transfer -- Soviet Research, v.21, no.2, 1989, p.213.

  9. Vertical feed stick wood fuel burning furnace system

    DOEpatents

    Hill, Richard C.

    1984-01-01

    A new and improved stove or furnace for efficient combustion of wood fuel including a vertical feed combustion chamber for receiving and supporting wood fuel in a vertical attitude or stack, a major upper portion of the combustion chamber column comprising a water jacket for coupling to a source of water or heat transfer fluid and for convection circulation of the fluid for confining the locus of wood fuel combustion to the bottom of the vertical gravity feed combustion chamber. A flue gas propagation delay channel extending from the laterally directed draft outlet affords delayed travel time in a high temperature environment to assure substantially complete combustion of the gaseous products of wood burning with forced air as an actively induced draft draws the fuel gas and air mixture laterally through the combustion and high temperature zone. Active sources of forced air and induced draft are included, multiple use and circuit couplings for the recovered heat, and construction features in the refractory material substructure and metal component superstructure.

  10. Vertical variations of charged-particle temperature and density in quiet conditions

    NASA Astrophysics Data System (ADS)

    Apati, I.; Semerei, T.; Afonin, V.; Bezrukikh, V.; Shiutte, N.; Bentse, P.

    1983-09-01

    Electrostatic analyzers aboard the Vertical-6 rocket were used to study vertical variations of charged-particle temperature and density at heights of 200-1200 km during quiet-solar conditions on October 25, 1977. The heating of the electron-ion gas was found to have an essentially nonmonotonic character. Above the F-region maximum, significant fluctuations of ion-gas temperature were observed, apparently associated with vertical variations of cooling and heating due to the excitation of the fine structure of atomic-oxygen levels as well as due to the effect of ion-exchange reactions. The maximum heating of ion gas occurs at heights where hydrogen ions begin to predominate. It is noted that the results obtained can be used to improve existing ionospheric models relating to periods of low solar activity.

  11. On the Conservation of the Vertical Action in Galactic Disks

    NASA Astrophysics Data System (ADS)

    Vera-Ciro, Carlos; D'Onghia, Elena

    2016-06-01

    We employ high-resolution N-body simulations of isolated spiral galaxy models, from low-amplitude, multi-armed galaxies to Milky Way-like disks, to estimate the vertical action of ensembles of stars in an axisymmetrical potential. In the multi-armed galaxy the low-amplitude arms represent tiny perturbations of the potential, hence the vertical action for a set of stars is conserved, although after several orbital periods of revolution the conservation degrades significantly. For a Milky Way-like galaxy with vigorous spiral activity and the formation of a bar, our results show that the potential is far from steady, implying that the action is not a constant of motion. Furthermore, because of the presence of high-amplitude arms and the bar, considerable in-plane and vertical heating occurs that forces stars to deviate from near-circular orbits, reducing the degree at which the actions are conserved for individual stars, in agreement with previous results, but also for ensembles of stars. If confirmed, this result has several implications, including the assertion that the thick disk of our Galaxy forms by radial migration of stars, under the assumption of the conservation of the action describing the vertical motion of stars.

  12. Vertically aligned nanostructure scanning probe microscope tips

    DOEpatents

    Guillorn, Michael A.; Ilic, Bojan; Melechko, Anatoli V.; Merkulov, Vladimir I.; Lowndes, Douglas H.; Simpson, Michael L.

    2006-12-19

    Methods and apparatus are described for cantilever structures that include a vertically aligned nanostructure, especially vertically aligned carbon nanofiber scanning probe microscope tips. An apparatus includes a cantilever structure including a substrate including a cantilever body, that optionally includes a doped layer, and a vertically aligned nanostructure coupled to the cantilever body.

  13. A design for vertical crossing insertions

    SciTech Connect

    Garren, A.

    1985-10-01

    A crossing insertion designed for an SSC with vertically separated 1-in-1 beam lines is presented in this note. The author supposes that the beam lines consist of separate magnets in separate cryostats separated by about 70 cm. He then describes the design, where vertical separation is done with four vertical dipoles producing a steplike beam line.

  14. 46 CFR 108.160 - Vertical ladders.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 4 2010-10-01 2010-10-01 false Vertical ladders. 108.160 Section 108.160 Shipping COAST... Construction and Arrangement Means of Escape § 108.160 Vertical ladders. (a) Each vertical ladder must have... inches) apart, uniform for the length of the ladder; and (3) At least 18 centimeters (7 inches) from...

  15. 46 CFR 108.160 - Vertical ladders.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 4 2011-10-01 2011-10-01 false Vertical ladders. 108.160 Section 108.160 Shipping COAST... Construction and Arrangement Means of Escape § 108.160 Vertical ladders. (a) Each vertical ladder must have... inches) apart, uniform for the length of the ladder; and (3) At least 18 centimeters (7 inches) from...

  16. Vertical Lift - Not Just For Terrestrial Flight

    NASA Technical Reports Server (NTRS)

    Young, Larry A

    2000-01-01

    Autonomous vertical lift vehicles hold considerable potential for supporting planetary science and exploration missions. This paper discusses several technical aspects of vertical lift planetary aerial vehicles in general, and specifically addresses technical challenges and work to date examining notional vertical lift vehicles for Mars, Titan, and Venus exploration.

  17. Heating Saturn's Clumpy Rings

    NASA Astrophysics Data System (ADS)

    Turner, Neal J.; Morishima, Ryuji; Spilker, Linda J.

    2015-11-01

    We model Cassini CIRS data using a Monte Carlo radiative transfer -- thermal balance technique first developed for protostellar disks, with the goals of:1. Exploring whether the A- and B-ring temperatures' variation with viewing angle is consistent with the wake structures suggested by the observed azimuthal asymmetry in optical depth, by analytic arguments, and by numerical N-body modeling.2. Better constraining the shape, size, spacing and optical depths of substructure in the A-ring, using the unexpectedly high temperatures observed at equinox. If the wake features have high enough contrast, Saturn-shine may penetrate the gaps between the wakes and heat thering particles both top and bottom.3. Determining how much of the heating of the A- and B-rings' unlit sides is due to radiative transport and how much is due to particle motions, especially vertical motions. This will help in constraining the rings' surface densities and masses.

  18. Heat Illness

    MedlinePlus

    ... breathing and a fast, weak pulse Heat cramps - muscle pains or spasms that happen during heavy exercise Heat rash - skin irritation from excessive sweating Centers for Disease Control and Prevention

  19. Heat Stress

    MedlinePlus

    ... Stress Learn some tips to protect workers including: acclimatization, rest breaks, and fluid recommendations. NIOSH Workplace Solution: ... Blog: Adjusting to Work in the Heat: Why Acclimatization Matters The natural adaptation to the heat takes ...

  20. Heating Structures Derived from Satellite

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Adler, R.; Haddad, Z.; Hou, A.; Kakar, R.; Krishnamurti, T. N.; Kummerow, C.; Lang, S.; Meneghini, R.; Olson, W.

    2004-01-01

    Rainfall is a key link in the hydrologic cycle and is a primary heat source for the atmosphere. The vertical distribution of latent-heat release, which is accompanied by rainfall, modulates the large-scale circulations of the tropics and in turn can impact midlatitude weather. This latent heat release is a consequence of phase changes between vapor, liquid, and solid water. The Tropical Rainfall Measuring Mission (TRMM), a joint U.S./Japan space project, was launched in November 1997. It provides an accurate measurement of rainfall over the global tropics which can be used to estimate the four-dimensional structure of latent heating over the global tropics. The distributions of rainfall and inferred heating can be used to advance our understanding of the global energy and water cycle. This paper describes several different algorithms for estimating latent heating using TRMM observations. The strengths and weaknesses of each algorithm as well as the heating products are also discussed. The validation of heating products will be exhibited. Finally, the application of this heating information to global circulation and climate models is presented.

  1. ?Vertical Sextants give Good Sights?

    NASA Astrophysics Data System (ADS)

    Richey, Michael

    Mark Dixon suggests (Forum, Vol. 50, 137) that nobody thus far has attempted to quantify the errors from tilt that arise while observing with the marine sextant. The issue in fact, with the related problem of what exactly is the axis about which the sextant is rotated whilst being (to define the vertical), was the subject of a lively controversy in the first two volumes of this Journal some fifty years ago. Since the consensus of opinion seems to have been that the maximum error does not necessarily occur at 45 degrees, whereas Dixon's table suggests that it does, some reiteration of the arguments may be in order.

  2. Vertical jumping and signaled avoidance

    PubMed Central

    Cándido, Antonio; Maldonado, Antonio; Vila, Jaime

    1988-01-01

    This paper reports an experiment intended to demonstrate that the vertical jumping response can be learned using a signaled-avoidance technique. A photoelectric cell system was used to record the response. Twenty female rats, divided equally into two groups, were exposed to intertrial intervals of either 15 or 40 s. Subjects had to achieve three successive criteria of acquisition: 3, 5, and 10 consecutive avoidance responses. Results showed that both groups learned the avoidance response, requiring increasingly larger numbers of trials as the acquisition criteria increased. No significant effect of intertrial interval was observed. PMID:16812559

  3. Neighbourly polytopes with few vertices

    SciTech Connect

    Devyatov, Rostislav A

    2011-10-31

    A family of neighbourly polytopes in R{sup 2d} with N=2d+4 vertices is constructed. All polytopes in the family have a planar Gale diagram of a special type, namely, with exactly d+3 black points in convex position. These Gale diagrams are parametrized by 3-trees (trees with a certain additional structure). For all polytopes in the family, the number of faces of dimension m containing a given vertex A depends only on d and m. Bibliography: 7 titles.

  4. Heat exchanger

    DOEpatents

    Daman, Ernest L.; McCallister, Robert A.

    1979-01-01

    A heat exchanger is provided having first and second fluid chambers for passing primary and secondary fluids. The chambers are spaced apart and have heat pipes extending from inside one chamber to inside the other chamber. A third chamber is provided for passing a purge fluid, and the heat pipe portion between the first and second chambers lies within the third chamber.

  5. ATLAS LTCS Vertically Challenged System Lessons Learned

    NASA Technical Reports Server (NTRS)

    Patel, Deepak; Garrison, Matt; Ku, Jentung

    2014-01-01

    Re-planning of LTCS TVAC testing and supporting RTA (Receiver Telescope Assembly) Test Plan and Procedure document preparation. The Laser Thermal Control System (LTCS) is designed to maintain the lasers onboard Advanced Topographic Laser Altimeter System (ATLAS) at their operational temperatures. In order to verify the functionality of the LTCS, a thermal balance test of the thermal hardware was performed. During the first cold start of the LTCS, the Loop Heat Pipe (LHP) was unable to control the laser mass simulators temperature. The control heaters were fully on and the loop temperature remained well below the desired setpoint. Thermal analysis of the loop did not show these results. This unpredicted behavior of the LTCS was brought up to a panel of LHP experts. Based on the testing and a review of all the data, there were multiple diagnostic performed in order to narrow down the cause. The prevailing theory is that gravity is causing oscillating flow within the loop, which artificially increased the control power needs. This resulted in a replan of the LTCS test flow and the addition of a GSE heater to allow vertical operation.

  6. Horizontally integrated atmospheric heat flux from an Arctic lead

    NASA Astrophysics Data System (ADS)

    Glendening, John W.

    1995-03-01

    Vertical distribution of the horizontally integrated heat injected into the atmosphere by an Arctic lead is investigated, based upon large-eddy simulations of its convective plume. The horizontally integrated heat flux varies exponentially with height except under conditions of relatively weak cross flow, when vertical advective transport becomes significant. Its vertical scale, which depends upon the lead size, surface heat flux, atmospheric stratification, and cross-lead wind component, is approximately one fourth of the maximum plume height, indicating that the depth of largest heat transfer is significantly shallower than the depth of the plume. A parameterization is developed to incorporate this small-scale heat injection into large-scale models which cannot resolve individual leads. The amount of heat recaptured by the ice downwind of a lead is significant when cross-lead flow is relatively strong and when the plume depth is shallow.

  7. Vertically coupled dipolar exciton molecules

    NASA Astrophysics Data System (ADS)

    Cohen, Kobi; Khodas, Maxim; Laikhtman, Boris; Santos, Paulo V.; Rapaport, Ronen

    2016-06-01

    While the interaction potential between two dipoles residing in a single plane is repulsive, in a system of two vertically adjacent layers of dipoles it changes from repulsive interaction in the long range to attractive interaction in the short range. Here we show that for dipolar excitons in semiconductor heterostructures, such a potential may give rise to bound states if two such excitons are excited in two separate layers, leading to the formation of vertically coupled dipolar exciton molecules. Our calculations prove the existence of such bound states and predict their binding energy as a function of the layers separation as well as their thermal distributions. We show that these molecules should be observed in realistic systems such as semiconductor coupled quantum well structures and the more recent van der Waals bound heterostructures. Formation of such molecules can lead to new effects such as a collective dipolar drag between layers and new forms of multiparticle correlations, as well as to the study of dipolar molecular dynamics in a controlled system.

  8. Laser tracking for vertical control

    NASA Technical Reports Server (NTRS)

    Dunn, Peter; Torrence, Mark; Pavlis, Erricos; Kolenkiewicz, Ron; Smith, David

    1993-01-01

    The Global Laser Tracking Network has provided LAGEOS ranging data of high accuracy since the first MERIT campaign in late 1983 and we can now resolve centimeter-level three dimensional positions of participating observatories at monthly intervals. In this analysis, the station height estimates have been considered separately from the horizontal components, and can be determined by the strongest stations with a formal standard error of 2 mm using eight years of continuous observations. The rate of change in the vertical can be resolved to a few mm/year, which is at the expected level of several geophysical effects. In comparing the behavior of the stations to that predicted by recent models of post-glacial rebound, we find no correlation in this very small effect. Particular attention must be applied to data and survey quality control when measuring the vertical component, and the survey observations are critical components of the geodynamic results. Seasonal patterns are observed in the heights of most stations, and the possibility of secular motion at the level of several millimeters per year cannot be excluded. Any such motion must be considered in the interpretation of horizontal inter-site measurements, and can help to identify mechanisms which can cause variations which occur linearly with time, seasonally, or abruptly.

  9. Heat Pipes

    NASA Technical Reports Server (NTRS)

    1991-01-01

    Phoenix Refrigeration Systems, Inc.'s heat pipe addition to the Phoenix 2000, a supermarket rooftop refrigeration/air conditioning system, resulted from the company's participation in a field test of heat pipes. Originally developed by NASA to control temperatures in space electronic systems, the heat pipe is a simple, effective, heat transfer system. It has been used successfully in candy storage facilities where it has provided significant energy savings. Additional data is expected to fully quantify the impact of the heat pipes on supermarket air conditioning systems.

  10. Heat Pipes

    NASA Technical Reports Server (NTRS)

    1996-01-01

    Heat Pipes were originally developed by NASA and the Los Alamos Scientific Laboratory during the 1960s to dissipate excessive heat build- up in critical areas of spacecraft and maintain even temperatures of satellites. Heat pipes are tubular devices where a working fluid alternately evaporates and condenses, transferring heat from one region of the tube to another. KONA Corporation refined and applied the same technology to solve complex heating requirements of hot runner systems in injection molds. KONA Hot Runner Systems are used throughout the plastics industry for products ranging in size from tiny medical devices to large single cavity automobile bumpers and instrument panels.

  11. Rapid vertical tectonics in ductile continental crust

    NASA Astrophysics Data System (ADS)

    Pearse, Jillian

    Research over the past two decades has shown that in regions of moderately high heat flow, the lower continental crust is ductile enough to flow on geological timescales. Vertical motions taking place within continental interiors produce localized features such as intracratonic basins and domes, and the results of this thesis indicate that ductile crustal flow can contribute significantly to the formation of these otherwise enigmatic features. A major goal of this thesis has been to analyze, quantitatively, the behaviour of loaded continental crust where a ductile layer is present. Specifically, I examine the long-term effects of sublithospheric heating events on crust with embedded density loads. Density anomalies within the crust can be initially supported by elastic stresses but sag appreciably if the elastic crust is thinned modestly. Beginning with a semi-analytic approach, I estimate the additional subsidence that would result from thermal reactivation, and introduce the previously unmodelled phenomenon of thermal annealing of stresses at the base of the elastic crust. In basins caused by intracrustal density loads, reactivated subsidence can be significant (of the order of 1 km, enough to account for about one quarter of the total Michigan basin subsidence). If the crust is sufficiently weakened, the long-term result is detachment of the load followed by rebound and inversion of the basin to form a dome. To model this phenomenon I use a full thermal and viscoelastic finite-element model, and find that such load detachment can occur for geologically reasonable load densities in high heat flow regions. Strikingly, the total upward displacement of material from depth during rebound can be as much as 10 km, enough to exhume the basin completely and expose basement rocks to some depth. Exhumation is rapid, lasting only about 5 to 10 million years. This raises the interesting question of what field evidence might support such a history for a dome: the results of

  12. Experimental natural convection on vertical surfaces for building integrated photovoltaic (BIPV) applications

    SciTech Connect

    Fossa, M.; Menezo, C.; Leonardi, E.

    2008-02-15

    An experimental study on natural convection in an open channel is carried out in order to investigate the effect of the geometrical configuration of heat sources on the heat transfer behaviour. To this aim, a series of vertical heaters are cooled by natural convection of air flowing between two parallel walls. The objective of the work is to investigate the physical mechanisms which influence the thermal behaviour of a double-skin photovoltaic (PV) facade. This results in a better understanding of the related phenomena and infers useful engineering information for controlling the energy transfers from the environment to the PV surfaces and from the PV surfaces to the building. Furthermore increasing the heat transfer rate from the PV surfaces increases the conversion efficiency of the PV modules since they operate better as their temperature is lower. The test section consists in a double vertical wall, 2 m high, and each wall is constituted by 10 different heating modules 0.2 m high. The heater arrangement simulates, at a reduced scale, the presence of a series of vertical PV modules. The heat flux at the wall ranges from 75 to 200 W/m{sup 2}. In this study, the heated section is 1.6 m in height, preceded by an adiabatic of 0.4 m in height. Different heating configurations are analyzed, including the uniform heating mode and two different configurations of non uniform, alternate heating. The experimental procedure allows the wall surface temperature, local heat transfer coefficient and local and average Nusselt numbers to be inferred. The experimental evidences show that the proper selection of the separating distance and heating configuration can noticeably decrease the surface temperatures and hence enhance the conversion efficiency of PV modules. (author)

  13. Meridional heat transport at the onset of winter stratospheric warming

    NASA Technical Reports Server (NTRS)

    Conte, M.

    1981-01-01

    A continuous vertical flow of energy toward high altitude was verified. This process produced a dynamic instability of the stratospheric polar vortex. A meridional heat transport ws primed toward the north, which generated a warming trend.

  14. Entirely passive heat pipe apparatus capable of operating against gravity

    DOEpatents

    Koenig, Daniel R.

    1982-01-01

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 meters and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  15. Importance of capturing heliospheric variability for studies of thermospheric vertical winds

    NASA Astrophysics Data System (ADS)

    Yiǧit, Erdal; Ridley, Aaron J.; Moldwin, Mark B.

    2012-07-01

    Using the Global Ionosphere Thermosphere Model with observed real-time heliospheric input data, the magnitude and variability of thermospheric neutral vertical winds are investigated. In order to determine the role of variability in the Interplanetary Magnetic Field (IMF) and solar wind density on the neutral wind variability, the heliospheric input data are smoothed. The effects of smoothing the IMF and solar wind and density on the vertical winds are simulated for the cases of no smoothing, 5-minute, and 12-minute smoothing. Various vertical wind acceleration terms, such as the nonhydrostatic acceleration, are quantified. Polar stereographic projections of the variabilities of vertical wind and ion flows are compared to highlight existing correlations. Overall, the smoother, that is, the less variable the IMF and solar wind parameters are, the weaker are the magnitude and the variability of the thermospheric vertical winds. Weaker IMF variability leads to smaller variability in ion flows, which in turn negatively impacts the variability and the magnitude of Joule heating. Small-scale temporal variation of the vertical wind acceleration, and thus the variability of the vertical wind, is dominated by the nonhydrostatic term that is controlled primarily by the temporal variation of the Joule heating, which in turn is related to ion flow variations that are shaped by the IMF in the high-latitude thermosphere. Wavelet analysis of the vertical wind data shows that gravity waves of ˜5 and ˜10-minute periods are more prominent when the model is run with high-resolution real-time IMF and solar wind data. Better capturing of the temporal variation of the IMF and solar wind parameters is crucial for modeling the variability and magnitude of thermospheric vertical winds.

  16. Low gravity exothermic heating/cooling apparatus

    NASA Technical Reports Server (NTRS)

    Poorman, R. M. (Inventor)

    1985-01-01

    A low gravity exothermic heating/cooling apparatus is disclosed for processing materials in space which includes an insulated casing and a sample support carried within the casing which support a sample container. An exothermic heat source includes a plurality of segments of exothermic material stacked one upon another to produce a desired temperature profile when ignited. The sample container is arranged within the core of the stacked exothermic heating material. Igniters are spaced vertically along the axis of the heating material to ignite the exothermic material at spaced points to provide total rapid burn and release of heat. To rapidly cool and quench the heat, a source of liquid carbon dixoide is provided which is conveyed through a conduit and a metering orifice into a distribution manifold where the carbon dioxide is gasified and dispersed around the exothermic heating material and the sample container via tubes for rapidly cooling the material sample.

  17. Sensible and latent heating of the atmosphere as inferred from DST-6 data

    NASA Technical Reports Server (NTRS)

    Herman, G. F.; Schubert, S. D.; Johnson, W. T.

    1979-01-01

    The average distribution of convective latent heating, boundary layer sensible heat flux, and vertical velocity are determined for the winter 1976 DST period from GLAS model diagnostics. Key features are the regions of intense latent heating over Brazil, Central Africa, and Indonesia; and the regions of strong sensible heating due to air mass modification over the North Atlantic and North Pacific Oceans.

  18. Natural convection of ferrofluids in partially heated square enclosures

    NASA Astrophysics Data System (ADS)

    Selimefendigil, Fatih; Öztop, Hakan F.; Al-Salem, Khaled

    2014-12-01

    In this study, natural convection of ferrofluid in a partially heated square cavity is numerically investigated. The heater is located to the left vertical wall and the right vertical wall is kept at constant temperature lower than that of the heater. Other walls of the square enclosure are assumed to be adiabatic. Finite element method is utilized to solve the governing equations. The influence of the Rayleigh number (104≤Ra≤5×105), heater location (0.25H≤yh≤0.75H), strength of the magnetic dipole (0≤γ≤2), horizontal and vertical location of the magnetic dipole (-2H≤a≤-0.5H, 0.2H≤b≤0.8H) on the fluid flow and heat transfer characteristics are investigated. It is observed that different velocity components within the square cavity are sensitive to the magnetic dipole source strength and its position. The length and size of the recirculation zones adjacent to the heater can be controlled with magnetic dipole strength. Averaged heat transfer increases with decreasing values of horizontal position of the magnetic dipole source. Averaged heat transfer value increases from middle towards both ends of the vertical wall when the vertical location of the dipole source is varied. When the heater location is changed, a symmetrical behavior in the averaged heat transfer plot is observed and the minimum value of the averaged heat transfer is attained when the heater is located at the mid of vertical wall.

  19. Numerical Simulation of Liquid Nitrogen Chilldown of a Vertical Tube

    NASA Technical Reports Server (NTRS)

    Darr, Samuel; Hu, Hong; Schaeffer, Reid; Chung, Jacob; Hartwig, Jason; Majumdar, Alok

    2015-01-01

    This paper presents the results of a one-dimensional numerical simulation of the transient chilldown of a vertical stainless steel tube with liquid nitrogen. The direction of flow is downward (with gravity) through the tube. Heat transfer correlations for film, transition, and nucleate boiling, as well as critical heat flux, rewetting temperature, and the temperature at the onset of nucleate boiling were used to model the convection to the tube wall. Chilldown curves from the simulations were compared with data from 55 recent liquid nitrogen chilldown experiments. With these new correlations the simulation is able to predict the time to rewetting temperature and time to onset of nucleate boiling to within 25% for mass fluxes ranging from 61.2 to 1150 kg/(sq m s), inlet pressures from 175 to 817 kPa, and subcooled inlet temperatures from 0 to 14 K below the saturation temperature.

  20. Use of temperature profiles beneath streams to determine rates of vertical ground-water flow and vertical hydraulic conductivity

    USGS Publications Warehouse

    Lapham, Wayne W.

    1989-01-01

    The use of temperature profiles beneath streams to determine rates of vertical ground-water flow and effective vertical hydraulic conductivity of sediments was evaluated at three field sites by use of a model that numerically solves the partial differential equation governing simultaneous vertical flow of fluid and heat in the Earth. The field sites are located in Hardwick and New Braintree, Mass., and in Dover, N.J. In New England, stream temperature varies from about 0 to 25 ?C (degrees Celsius) during the year. This stream-temperature fluctuation causes ground-water temperatures beneath streams to fluctuate by more than 0.1 ?C during a year to a depth of about 35 ft (feet) in fine-grained sediments and to a depth of about 50 ft in coarse-grained sediments, if ground-water velocity is 0 ft/d (foot per day). Upward flow decreases the depth affected by stream-temperature fluctuation, and downward flow increases the depth. At the site in Hardwick, Mass., ground-water flow was upward at a rate of less than 0.01 ft/d. The maximum effective vertical hydraulic conductivity of the sediments underlying this site is 0.1 ft/d. Ground-water velocities determined at three locations at the site in New Braintree, Mass., where ground water discharges naturally from the underlying aquifer to the Ware River, ranged from 0.10 to 0.20 ft/d upward. The effective vertical hydraulic conductivity of the sediments underlying this site ranged from 2.4 to 17.1 ft/d. Ground-water velocities determined at three locations at the Dover, N.J., site, where infiltration from the Rockaway River into the underlying sediments occurs because of pumping, were 1.5 ft/d downward. The effective vertical hydraulic conductivity of the sediments underlying this site ranged from 2.2 to 2.5 ft/d. Independent estimates of velocity at two of the three sites are in general agreement with the velocities determined using temperature profiles. The estimates of velocities and conductivities derived from the

  1. Vertical Structure of Magnetized Accretion Disks around Young Stars

    NASA Astrophysics Data System (ADS)

    Lizano, S.; Tapia, C.; Boehler, Y.; D'Alessio, P.

    2016-01-01

    We model the vertical structure of the magnetized accretion disks that are subject to viscous and resistive heating and irradiation by the central star. We apply our formalism to the radial structure of the magnetized accretion disks that are threaded by the poloidal magnetic field dragged during the process of star formation, which was developed by Shu and coworkers. We consider disks around low-mass protostars, T Tauri, and FU Orionis stars, as well as two levels of disk magnetization: {λ }{sys}=4 (strongly magnetized disks) and {λ }{sys}=12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk, and the T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, which is consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (˜90%-95%) is in the disk midplane. With the advent of ALMA one expects direct measurements of magnetic fields and their morphology at disk scales. It will then be possible to determine the mass-to-flux ratio of magnetized accretion disks around young stars, an essential parameter for their structure and evolution. Our models contribute to the understanding of the vertical structure and emission of these disks.

  2. Advancements of vertically aligned liquid crystal displays.

    PubMed

    Kumar, Pankaj; Jaggi, Chinky; Sharma, Vandna; Raina, Kuldeep Kumar

    2016-02-01

    This review describes the recent advancements in the field of the vertical aligned (VA) liquid crystal displays. The process and formation of different vertical alignment modes such as conventional VA, patterned VA, multi-domain VA, and polymer stabilised VA etc are widely discussed. Vertical alignment of liquid crystal due to nano particle dispersion in LC host, bifunctional PR-SAM formed by silane coupling reaction to oxide surfaces, azo dye etc., are also highlighted and discussed. Overall, the article highlights the advances in the research of vertical aligned liquid crystal in terms of their scientific and technological aspects.

  3. On the Vertical Gradient in CO2

    NASA Astrophysics Data System (ADS)

    Stine, A. R.; Fung, I. Y.

    2008-12-01

    Attempts to constrain surface fluxes of carbon from atmospheric measurements of carbon dioxide have primarily focused on surface boundary layer measurements, because information about surface fluxes is least diluted close to the locations where the fluxes occur. However, errors in model ventilation of air in the vertical can be misinterpreted as local surface fluxes. Satellites which measure column integrated CO2 are expected to represent a major advance in part because they observe the entire atmospheric column. Recent work has highlighted the fact that vertical gradients in carbon concentrations can give us information about where vertical mixing errors are likely to be misinterpreted as local surface fluxes, but passive tracer evidence suggests that models that capture vertical profiles on the ocean do poorly on the land (and vice versa), suggesting that the problem of correctly treating vertical mixing in inverse studies is more fundamental than picking the "best" model. We consider observations of the vertical gradient in CO2 from aircrafts and from a comparison of satellites that observe in the near infrared (which observe the column integrated CO2 field) and the thermal infrared (which observe the upper troposphere). We evaluate the feasibility of using these satellites for determining the vertical gradient in CO2. We examine how observations of the vertical gradient of CO2 allow us to differentiate the imprint of vertical mixing and the imprint in surface fluxes on the observed field of atmospheric CO2.

  4. Vertical motion requirements for landing simulation

    NASA Technical Reports Server (NTRS)

    Bray, R. S.

    1973-01-01

    Tests were conducted to determine the significance of vertical acceleration cues in the simulation of the visual approach and landing maneuver. Landing performance measures were obtained for four subject pilots operating a visual landing simulation device which provides up to plus or minus 40 feet of vertical motion. Test results indicate that vertical motion cues are utilized in the landing task, and that they are particularly important in the simulation of aircraft with marginal longitudinal handling qualities. To assure vertical motion cues of the desired fidelity in the landing tasks, it appears that a simulator must have excursion capabilities of at least plus or minus 20 feet.

  5. Vertical Diffusivities of Active and Passive Tracers

    NASA Technical Reports Server (NTRS)

    Canuto, V. M.; Cheng, Y.; Howard, A. M.

    2010-01-01

    The climate models that include a carbon-cycle need the vertical diffusivity of a passive tracer. Since an expression for the latter is not available, it has been common practice to identify it with that of salt. The identification is questionable since T, S are active, not passive tracers. We present the first derivation of the diffusivity of a passive tracer in terms of Ri (Richardson number) and Rq (density ratio, ratio of salinity over temperature z-gradients). The following results have emerged: (a) The passive tracer diffusivity is an algebraic function of Ri, Rq. (b) In doubly stable regimes (DS, partial derivative of T with respect to z > 0, partial derivative of S with respect to z < 0), the passive scalar diffusivity is nearly the same as that of salt/heat for any values of Rq < 0 and Ri > 0. (c) In DC regimes (diffusive convection, partial derivative of T with respect to z < 0, partial derivative of S with respect to z < 0, Rq > 1), the passive scalar diffusivity is larger than that of salt. At Ri = O(1), it can be more than twice as large. (d) In SF regimes (salt fingers, partial derivative of T with respect to z > 0, partial derivative of S with respect to z > 0, Rq < 1), the passive scalar diffusivity is smaller than that of salt. At Ri = O(1), it can be less than half of it. (e) The passive tracer diffusivity predicted at the location of NATRE (North Atlantic Tracer Release Experiment) is discussed. (f) Perhaps the most relevant conclusion is that the common identification of the tracer diffusivity with that of salt is valid only in DS regimes. In the Southern Ocean, where there is the largest CO2 absorption, the dominant regime is diffusive convection discussed in (c) above.

  6. Heat Problems.

    ERIC Educational Resources Information Center

    Connors, G. Patrick

    Heat problems and heat cramps related to jogging can be caused by fluid imbalances, medications, dietary insufficiency, vomiting or diarrhea, among other factors. If the condition keeps reoccurring, the advice of a physician should be sought. Some preventive measures that can be taken include: (1) running during the cooler hours of the day; (2)…

  7. Vertically transmitted symbiont reduces host fitness along temperature gradient.

    PubMed

    Dusi, E; Krenek, S; Schrallhammer, M; Sachse, R; Rauch, G; Kaltz, O; Berendonk, T U

    2014-04-01

    Parasites with exclusive vertical transmission from host parent to offspring are an evolutionary puzzle. With parasite fitness entirely linked to host reproduction, any fitness cost for infected hosts risks their selective elimination. Environmental conditions likely influence parasite impact and thereby the success of purely vertical transmission strategies. We tested for temperature-dependent virulence of Caedibacter taeniospiralis, a vertically transmitted bacterial symbiont of the protozoan Paramecium tetraurelia. We compared growth of infected and cured host populations at five temperatures (16–32 °C). Infection reduced host density at all temperatures, with a peak of −30% at 28 °C. These patterns were largely consistent across five infected Paramecium strains. Similar to Wolbachia symbionts, C. taeniospiralis may compensate fitness costs by conferring to the host a ‘killer trait’, targeting uninfected competitors. Considerable loss of infection at 32 °C suggests that killer efficacy is not universal and that limited heat tolerance restricts the conditions for persistence of C. taeniospiralis. PMID:24779056

  8. Heating rates in tropical anvils

    NASA Technical Reports Server (NTRS)

    Ackerman, Thomas P.; Valero, Francisco P. J.; Pfister, Leonhard; Liou, Kuo-Nan

    1988-01-01

    The interaction of infrared and solar radiation with tropical cirrus anvils is addressed. Optical properties of the anvils are inferred from satellite observations and from high-altitude aircraft measurements. An infrared multiple-scattering model is used to compute heating rates in tropical anvils. Layer-average heating rates in 2 km thick anvils were found to be on the order of 20 to 30 K/day. The difference between heating rates at cloud bottom and cloud top ranges from 30 to 200 K/day, leading to convective instability in the anvil. The calculations are most sensitive to the assumed ice water content, but also are affected by the vertical distribution of ice water content and by the anvil thickness. Solar heating in anvils is shown to be less important than infrared heating but not negligible. The dynamical implications of the computed heating rates are also explored and it is concluded that the heating may have important consequences for upward mass transport in the tropics. The potential impact of tropical cirrus on the tropical energy balance and cloud forcing are discussed.

  9. The Ames Vertical Gun Range

    NASA Technical Reports Server (NTRS)

    Karcz, J. S.; Bowling, D.; Cornelison, C.; Parrish, A.; Perez, A.; Raiche, G.; Wiens, J.-P.

    2016-01-01

    The Ames Vertical Gun Range (AVGR) is a national facility for conducting laboratory- scale investigations of high-speed impact processes. It provides a set of light-gas, powder, and compressed gas guns capable of accelerating projectiles to speeds up to 7 km s(exp -1). The AVGR has a unique capability to vary the angle between the projectile-launch and gravity vectors between 0 and 90 deg. The target resides in a large chamber (diameter approximately 2.5 m) that can be held at vacuum or filled with an experiment-specific atmosphere. The chamber provides a number of viewing ports and feed-throughs for data, power, and fluids. Impacts are observed via high-speed digital cameras along with investigation-specific instrumentation, such as spectrometers. Use of the range is available via grant proposals through any Planetary Science Research Program element of the NASA Research Opportunities in Space and Earth Sciences (ROSES) calls. Exploratory experiments (one to two days) are additionally possible in order to develop a new proposal.

  10. Rupture of vertical soap films

    NASA Astrophysics Data System (ADS)

    Rio, Emmanuelle

    2014-11-01

    Soap films are ephemeral and fragile objects. They tend to thin under gravity, which gives rise to the fascinating variations of colors at their interfaces but leads systematically to rupture. Even a child can create, manipulate and admire soap films and bubbles. Nevertheless, the reason why it suddenly bursts remains a mystery although the soap chosen to stabilize the film as well as the humidity of the air seem very important. One difficulty to study the rupture of vertical soap films is to control the initial solution. To avoid this problem we choose to study the rupture during the generation of the film at a controlled velocity. We have built an experiment, in which we measure the maximum length of the film together with its lifetime. The generation of the film is due to the presence of a gradient of surface concentration of surfactants at the liquid/air interface. This leads to a Marangoni force directed toward the top of the film. The film is expected to burst only when its weight is not balanced anymore by this force. We will show that this leads to the surprising result that the thicker films have shorter lifetimes than the thinner ones. It is thus the ability of the interface to sustain a surface concentration gradient of surfactants which controls its stability.

  11. Endoscopy of vertical banded gastroplasty.

    PubMed

    Deitel, M; Bendago, M

    1989-05-01

    Vertical banded gastroplasty is the most common operation for morbid obesity. Postoperative gastroscopy was needed 91 times in 79 of 696 patients for 1) abdominal pain (23), 2) excess vomiting (22), 3) inadequate weight loss (14), 4) excess weight loss (13), 5) and a sudden increase in eating capacity (7). A normal appearance consisted of a clean gastric channel 6.8 +/- 1.4 SD cm long, with a rosette 46.6 +/- 2.1 cm from the incisors and, with insufflation, an 11 mm scope passed through this pseudopylorus snugly, but without difficulty. In Group 1, no problem was seen in the channel, and cholecystitis was found to be the cause. In Group 2, no problem was observed in ten (poor teeth and chewing), six experienced stasis or pill ulcerations, four had bezoars (fragmented or removed with basket), and two had intraluminal mesh. In Group 3, the scope floated through too large an outlet (greater than or equal to 13 mm) in eight, and no cause was seen in six (gorgers, sweets-eaters). In Group 4, tightness or stricture resolved with dilatations (Eder-Puestow; Savary; balloon dilators) in six, but seven required re-operation. In Group 5, the scope travelled through four breakdowns in the partition and three outlets were too large. Gastroscopy viewed problems accurately, indicated treatment and suggested modifications in gastroplasty technique. PMID:2719405

  12. HL-20 Vertical Human Factors

    NASA Technical Reports Server (NTRS)

    1992-01-01

    The HL-20 space taxi, Langley's candidate personnel launch system, is one of several designs being considered by NASA as a complement to the Space Shuttle. Human factors studies, using Langley volunteers as subjects, have been ongoing since March 1991 to verify crew seating arrangements, habitability, ingress and egress, equipment layout and maintenance and handling operations, and to determine visibility requirements during docking and landing operations. Langley volunteers, wearing flight suits and helmets, were put through a series of tests with the craft placed both vertically and horizontally to simulate launch and landing attitudes, The HL-20 would be launched into a low orbit by an expendable rocket and then use its own propulsion system to boost itself to the space station. Following exchange of crews or delivery of small payload, the HL-20 would return to Earth like the space shuttle, making a runway landing near the launch site, The full-scale engineering research model of the HL-20 design was constructed by students and faculty at North Carolina State University and North Carolina A&T State University with the Mars Mission Research Center under a grant from NASA Langley.

  13. Vertical, natural circulation boiler for Tapada do Outeiro

    SciTech Connect

    1996-07-01

    With the new generation of high power, high temperature gas turbines, has come the demand for a tri-pressure reheat steam cycle to increase output and efficiency. As a result, designers are looking again at natural circulation heat recovery boilers, but with a vertical gas path. Tapada do Outeiro is probably the first project which has been specified with a vertical natural circulation configuration. Other boiler companies are experimenting with bypasses on the circulation pumps of tri-pressure boilers, so that natural circulation can be studied in a fully commercial environment. Effectively, the pumps are used at start-up, and then shut off so that the boiler effectively runs in natural circulation when stable conditions have been established. Although the plant is intended to run mainly for base load, it may also be used for load following with daily or weekly start. Aids to quick starting include provisions of weather damper to retain heat in the boiler overnight. There are no bypass stacks, but steam dumps to the condenser. The gas turbine exhausts straight into the cold boiler.

  14. Vertical Structure of Magnetized Accretion Disks Around Young Stars

    NASA Astrophysics Data System (ADS)

    Tapia, Carlos; Lizano, Susana

    2016-01-01

    We model the vertical structure of magnetized accretion disks subject to viscous and resistive heating, and irradiation by the central star. We apply our formalism to the radial structure of magnetized accretion disks threaded by a poloidal magnetic field dragged during the process of star formation developed by Shu and coworkers. We consider disks around low mass protostars, T Tauri, and FU Orionis stars. We consider two levels of disk magnetization, λsys = 4 (strongly magnetized disks), and λsys = 12 (weakly magnetized disks). The rotation rates of strongly magnetized disks have large deviations from Keplerian rotation. In these models, resistive heating dominates the thermal structure for the FU Ori disk. The T Tauri disk is very thin and cold because it is strongly compressed by magnetic pressure; it may be too thin compared with observations. Instead, in the weakly magnetized disks, rotation velocities are close to Keplerian, and resistive heating is always less than 7% of the viscous heating. In these models, the T Tauri disk has a larger aspect ratio, consistent with that inferred from observations. All the disks have spatially extended hot atmospheres where the irradiation flux is absorbed, although most of the mass (~ 90 - 95 %) is in the disk midplane.

  15. Passive heating of the ground surface

    NASA Astrophysics Data System (ADS)

    Tyburczyk, Anna

    2016-03-01

    The phenomenon of phase change is one of the most important contemporary issues of thermal engineering. In particular, this applies to all kinds of heat exchanger systems, which should achieve the highest possible efficiency while reducing investment and operating costs. Some of these systems are heat pipes or thermosyphons, which, among others, are used for the heat transfer, temperature stabilization and the regulation of heat flux density. Additionally, they are passive systems, and therefore do not require an external power supply. Heat pipes can be used to stabilize the surface temperature of roads and driveways. Large heat tubes can be applied for heating the surface of bridges and overpasses, which become icy in unfavorable climatic conditions. The paper presents research on the test facility, whose main component is a long vertical copper fin. The temperature at the base of the fin was kept constant for a given series of measurements. Heat receiving fluid was ethanol at atmospheric pressure. The measurement methodology and the results of investigations were discussed. The surface temperature distribution was measured with the infrared camera, and on this basis the local values of heat flow and the heat transfer coefficient were determined. The results were presented as boiling curves for both the fin with the smooth surface and the one covered with a metal capillary-porous structure. The results obtained are useful in the design of heat exchangers, including passive heating of the ground.

  16. Teaching Students the Verticality of Technical Documentation.

    ERIC Educational Resources Information Center

    Hager, Peter J.

    1992-01-01

    Advocates making technical writing courses more vertical in structure by including an extensive study of at least one specific form of technical documentation. Examines how students can gain experience in the vertical process by designing, writing, testing, and producing user manuals for on-campus cooperative education clients. Lists the benefits…

  17. Vertical Integration, Monopoly, and the First Amendment.

    ERIC Educational Resources Information Center

    Brennan, Timothy J.

    This paper addresses the relationship between the First Amendment, monopoly of transmission media, and vertical integration of transmission and content provision. A survey of some of the incentives a profit-maximizing transmission monopolist may have with respect to content is followed by a discussion of how vertical integration affects those…

  18. 33 CFR 84.19 - Vertical sectors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 33 Navigation and Navigable Waters 1 2010-07-01 2010-07-01 false Vertical sectors. 84.19 Section 84.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INLAND NAVIGATION RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.19 Vertical sectors. (a)...

  19. 33 CFR 84.19 - Vertical sectors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 1 2011-07-01 2011-07-01 false Vertical sectors. 84.19 Section 84.19 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY INLAND NAVIGATION RULES ANNEX I: POSITIONING AND TECHNICAL DETAILS OF LIGHTS AND SHAPES § 84.19 Vertical sectors. (a)...

  20. Vertical Files in Midlands Academic Libraries.

    ERIC Educational Resources Information Center

    Lillis, John G.

    1991-01-01

    Reviews survey responses from 127 nonmedical academic libraries in Nebraska, Iowa, and Kansas regarding their vertical files (e.g., acquisitions, weeding, size, nature, collection management, frequency of use, maintenance of statistics, types of users, circulation, and security), reporting that 109 had vertical files, with most emphasizing topics…

  1. [Vertical dimension in the Begg technic].

    PubMed

    Demange, C; Dion, J G

    1989-01-01

    This data of 25 treated cases in BEGG technic show, with RICKETTS analysis, a small augmentation of vertical dimensions during treatment. During retention, four of five factors improved. No correlation have been found between increase rate of vertical dimensions, treatment duration, and initial typology.

  2. Loading effects in GPS vertical displacement time series

    NASA Astrophysics Data System (ADS)

    Memin, A.; Boy, J. P.; Santamaría-Gómez, A.; Watson, C.; Gravelle, M.; Tregoning, P.

    2015-12-01

    Surface deformations due to loading, with yet no comprehensive representation, account for a significant part of the variability in geodetic time series. We assess effects of loading in GPS vertical displacement time series at several frequency bands. We compare displacement derived from up-to-date loading models to two global sets of positioning time series, and investigate how they are reduced looking at interannual periods (> 2 months), intermediate periods (> 7 days) and the whole spectrum (> 1day). We assess the impact of interannual loading on estimating velocities. We compute atmospheric loading effects using surface pressure fields from the ECMWF. We use the inverted barometer (IB) hypothesis valid for periods exceeding a week to describe the ocean response to the pressure forcing. We used general circulation ocean model (ECCO and GLORYS) to account for wind, heat and fresh water flux. We separately use the Toulouse Unstructured Grid Ocean model (TUGO-m), forced by air pressure and winds, to represent the dynamics of the ocean response at high frequencies. The continental water storage is described using GLDAS/Noah and MERRA-land models. Non-hydrology loading reduces the variability of the observed vertical displacement differently according to the frequency band. The hydrology loading leads to a further reduction mostly at annual periods. ECMWF+TUGO-m better agrees with vertical surface motion than the ECMWF+IB model at all frequencies. The interannual deformation is time-correlated at most of the locations. It is adequately described by a power-law process of spectral index varying from -1.5 to -0.2. Depending on the power-law parameters, the predicted non-linear deformation due to mass loading variations leads to vertical velocity biases up to 0.7 mm/yr when estimated from 5 years of continuous observations. The maximum velocity bias can reach up to 1 mm/yr in regions around the southern Tropical band.

  3. Cooling Requirements for the Vertical Shear Instability in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Lin, Min-Kai; Youdin, Andrew N.

    2015-09-01

    The vertical shear instability (VSI) offers a potential hydrodynamic mechanism for angular momentum transport in protoplanetary disks (PPDs). The VSI is driven by a weak vertical gradient in the disk’s orbital motion, but must overcome vertical buoyancy, a strongly stabilizing influence in cold disks, where heating is dominated by external irradiation. Rapid radiative cooling reduces the effective buoyancy and allows the VSI to operate. We quantify the cooling timescale tc needed for efficient VSI growth, through a linear analysis of the VSI with cooling in vertically global, radially local disk models. We find the VSI is most vigorous for rapid cooling with {t}{{c}}\\lt {{{Ω }}}{{K}}-1h| q| /(γ -1) in terms of the Keplerian orbital frequency, {{{Ω }}}{{K}}, the disk’s aspect-ratio, h\\ll 1, the radial power-law temperature gradient, q, and the adiabatic index, γ. For longer tc, the VSI is much less effective because growth slows and shifts to smaller length scales, which are more prone to viscous or turbulent decay. We apply our results to PPD models where tc is determined by the opacity of dust grains. We find that the VSI is most effective at intermediate radii, from ∼5 to ∼50 AU with a characteristic growth time of ∼30 local orbital periods. Growth is suppressed by long cooling times both in the opaque inner disk and the optically thin outer disk. Reducing the dust opacity by a factor of 10 increases cooling times enough to quench the VSI at all disk radii. Thus the formation of solid protoplanets, a sink for dust grains, can impede the VSI.

  4. Mixed convection aiding flow in a vertical porous annulus-two temperature model

    NASA Astrophysics Data System (ADS)

    Salman Ahmed, N. J.; AAAl-Rashed, Abdullah A.; Kamangar, Sarfaraz; Khaleed, H. M. T.; YunusKhan, T. M.; Athani, Abdulgaphur

    2016-09-01

    The effect of convective heat transfer on mixed convection flow in a vertical porous annulus embedded with fluid saturated porous medium for aiding flow is studied. The inner surface of the annular cylinder is heated with constant temperature whereas the outer surface remains at ambient temperature. The governing partial differential equations are solved using Finite Element Method (FEM). It is assumed that the Darcy law is applicable and thermal nonequilibrium TNE exists between solid and fluid phases of porous medium. The aiding flow behavior of heat transfer with respect to Radius ratioRr, Aspect ratio ArandRadiation parameter Rd for different values of Peclet number Peare investigated.

  5. Vertical-Cavity Surface-Emitting Lasers

    NASA Astrophysics Data System (ADS)

    Wilmsen, Carl W.; Temkin, Henryk; Coldren, Larry A.

    2002-01-01

    1. Introduction to VCSELs L. A. Coldren, C. W. Wilmsen and H. Temkin; 2. Fundamental issues in VCSEL design L. A. Coldren and Eric R. Hegblom; 3. Enhancement of spontaneous emission in microcavities E. F. Schubert and N. E. J. Hunt; 4. Epitaxy of vertical-cavity lasers R. P. Schneider Jr and Y. H. Young; 5. Fabrication and performance of vertical-cavity surface-emitting lasers Kent D. Choquette and Kent Geib; 6. Polarization related properties of vertical cavity lasers Dmitri Kuksenkov and Henryk Temkin; 7. Visible light emitting vertical cavity lasers Robert L. Thornton; 8. Long-wavelength vertical-cavity lasers Dubrakovo I. Babic, Joachim Piprek and John E. Bowers; 9. Overview of VCSEL applications Richard C. Williamson; 10. Optical interconnection applications and required characteristics Kenichi Kasahara; 11. VCSEL-based fiber-optic data communications Kenneth Hahn and Kirk Giboney; 12. VCSEL-based smart pixels for free space optoelectronic processing C. W. Wilmsen.

  6. Heat collector

    DOEpatents

    Merrigan, Michael A.

    1984-01-01

    A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

  7. Heat collector

    DOEpatents

    Merrigan, M.A.

    1981-06-29

    A heat collector and method suitable for efficiently and cheaply collecting solar and other thermal energy are provided. The collector employs a heat pipe in a gravity-assist mode and is not evacuated. The collector has many advantages, some of which include ease of assembly, reduced structural stresses on the heat pipe enclosure, and a low total materials cost requirement. Natural convective forces drive the collector, which after startup operates entirely passively due in part to differences in molecular weights of gaseous components within the collector.

  8. Heat-cured silicone bimaxillary mouthguard.

    PubMed

    Milward, P J; Jagger, R G

    1995-10-01

    A laboratory procedure for the construction of a heat-cured, silicone, custom-made bimaxillary mouthguard for contact sports is described. Contours and vertical dimension are easier to control than with the conventional thermoformed product, and there is no danger of injury from contact between the maxillary and mandibular components.

  9. Study of the Heat-Transfer Processes of Tubular Elements of Ground Heat Exchangers

    NASA Astrophysics Data System (ADS)

    Kusaiynov, K.; Shuyushbayeva, N. N.; Shaimerdenova, K. M.; Nurgalieva, Zh. G.; Omarov, N. N.

    2015-05-01

    In this paper, consideration is given to the efficiency of utilization of the low-potential heat of the ground. Also, the advantages and distinctive features of polyethylene tubes used in vertical tubular elements of heat pumps are described. This paper gives the results of investigation of the heat transfer of tubular elements of ground heat exchangers. The dependences of the temperature distributions in the ground in the vicinity of a tube and the change in the temperature with time in dry and moist grounds are determined.

  10. Advanced Si solid phase crystallization for vertical channel in vertical NANDs

    SciTech Connect

    Lee, Sangsoo; Son, Yong-Hoon; Hwang, Kihyun; Shin, Yoo Gyun; Yoon, Euijoon

    2014-07-01

    The advanced solid phase crystallization (SPC) method using the SiGe/Si bi-layer structure is proposed to obtain high-mobility poly-Si thin-film transistors in next generation vertical NAND (VNAND) devices. During the SPC process, the top SiGe thin film acts as a selective nucleation layer to induce surface nucleation and equiaxial microstructure. Subsequently, this SiGe thin film microstructure is propagated to the underlying Si thin film by epitaxy-like growth. The initial nucleation at the SiGe surface was clearly observed by in situ transmission electron microscopy (TEM) when heating up to 600 °C. The equiaxial microstructures of both SiGe nucleation and Si channel layers were shown in the crystallized bi-layer plan-view TEM measurements. Based on these experimental results, the large-grained and less-defective Si microstructure is expected to form near the channel region of each VNAND cell transistor, which may improve the electrical characteristics.

  11. Inclusion of Vertical Dynamics in Vertically-integrated Models for CO2 Storage

    NASA Astrophysics Data System (ADS)

    Guo, B.; Bandilla, K.; Celia, M. A.

    2012-12-01

    Mathematical models of different complexity are needed to answer a range of questions for geological sequestration of carbon dioxide (CO2). One category of simplified models is based on vertical integration, which reduces the three-dimensional problem to two dimensions. Usually, these models assume that brine and CO2 are in vertical equilibrium. This type of model is useful and accurate for simulation times that are large relative to the time for buoyant segregation. But, vertical-equilibrium models are inappropriate in some situations, for instance, in the early stage of injection, when brine and CO2 have not fully segregated. Therefore, for these situations, the vertical equilibrium assumption needs to be relaxed and vertical dynamics needs to be included in the governing equations. To avoid significant increases of computational effort due to the inclusion of vertical dynamics, a multi-scale algorithm can be constructed where the vertically integrated equations are still used to model the (dominant) horizontal flow processes with the vertical reconstruction included as a dynamic problem. Such an approach allows each vertical column of grid cells to be solved independently, as a one-dimensional problem, during the dynamic reconstruction step. Because the top and bottom boundaries usually correspond to impermeable caprock, the total flow for these one-dimensional problems is zero and counter-current flow driven only by buoyancy and capillarity is involved. Solutions for this kind of problem are relatively simple and require little computational effort. With careful coupling between the vertical calculations and the horizontally integrated equations, an efficient algorithm can be developed to simulate a fairly wide range of problems including those with significant vertical dynamics. When vertical dynamics become insignificant, then usual vertical equilibrium reconstruction is used in the vertically integrated models. This new algorithm provides an intermediate

  12. Heat intolerance

    MedlinePlus

    ... this page: //medlineplus.gov/ency/article/003094.htm Heat intolerance To use the sharing features on this ... must be authorized in writing by ADAM Health Solutions. About MedlinePlus Site Map FAQs Contact Us Get ...

  13. Corrosive resistant heat exchanger

    DOEpatents

    Richlen, Scott L.

    1989-01-01

    A corrosive and errosive resistant heat exchanger which recovers heat from a contaminated heat stream. The heat exchanger utilizes a boundary layer of innocuous gas, which is continuously replenished, to protect the heat exchanger surface from the hot contaminated gas. The innocuous gas is conveyed through ducts or perforations in the heat exchanger wall. Heat from the heat stream is transferred by radiation to the heat exchanger wall. Heat is removed from the outer heat exchanger wall by a heat recovery medium.

  14. Heating stove

    SciTech Connect

    Johnson, V.

    1982-03-23

    This stove invention relates to wood and coal burning stoves employed for heating. More effective draft control and heat transfer is achieved by a stove employing straight and serpentine flues, a control rod to coordinate movement of a baffle and damper for defining passageways to the flues, and a channel for apportioning air above and below the fuel and into first and second combustion chambers.

  15. HEAT EXCHANGER

    DOEpatents

    Fox, T.H. III; Richey, T. Jr.; Winders, G.R.

    1962-10-23

    A heat exchanger is designed for use in the transfer of heat between a radioactive fiuid and a non-radioactive fiuid. The exchanger employs a removable section containing the non-hazardous fluid extending into the section designed to contain the radioactive fluid. The removable section is provided with a construction to cancel out thermal stresses. The stationary section is pressurized to prevent leakage of the radioactive fiuid and to maintain a safe, desirable level for this fiuid. (AEC)

  16. HEAT2

    SciTech Connect

    Charman, C. )

    1993-08-01

    HEAT2 is a finite element program for the transient and steady-state, thermal analysis of two-dimensional solids. Calculates detailed temperature distributions in MHTGR prismatic fuel elements side reflector and core support blocks. Non-linear effects of time and temperature dependent boundary conditions, and heat source generation and material properties are included with user supplied subroutines NPBC, QAREA, SOURCE, and MPROP.

  17. Heating and Large Scale Dynamics of the Solar Corona

    NASA Technical Reports Server (NTRS)

    Schnack, Dalton D.

    2000-01-01

    The effort was concentrated in the areas: coronal heating mechanism, unstructured adaptive grid algorithms, numerical modeling of magnetic reconnection in the MRX experiment: effect of toroidal magnetic field and finite pressure, effect of OHMIC heating and vertical magnetic field, effect of dynamic MESH adaption.

  18. GEO3D - Three-Dimensional Computer Model of a Ground Source Heat Pump System

    SciTech Connect

    James Menart

    2013-06-07

    This file is the setup file for the computer program GEO3D. GEO3D is a computer program written by Jim Menart to simulate vertical wells in conjunction with a heat pump for ground source heat pump (GSHP) systems. This is a very detailed three-dimensional computer model. This program produces detailed heat transfer and temperature field information for a vertical GSHP system.

  19. Nanofluid impingement jet heat transfer.

    PubMed

    Zeitoun, Obida; Ali, Mohamed

    2012-02-17

    Experimental investigation to study the heat transfer between a vertical round alumina-water nanofluid jet and a horizontal circular round surface is carried out. Different jet flow rates, jet nozzle diameters, various circular disk diameters and three nanoparticles concentrations (0, 6.6 and 10%, respectively) are used. The experimental results indicate that using nanofluid as a heat transfer carrier can enhance the heat transfer process. For the same Reynolds number, the experimental data show an increase in the Nusselt numbers as the nanoparticle concentration increases. Size of heating disk diameters shows reverse effect on heat transfer. It is also found that presenting the data in terms of Reynolds number at impingement jet diameter can take into account on both effects of jet heights and nozzle diameter. Presenting the data in terms of Peclet numbers, at fixed impingement nozzle diameter, makes the data less sensitive to the percentage change of the nanoparticle concentrations. Finally, general heat transfer correlation is obtained verses Peclet numbers using nanoparticle concentrations and the nozzle diameter ratio as parameters.

  20. Nanofluid impingement jet heat transfer

    PubMed Central

    2012-01-01

    Experimental investigation to study the heat transfer between a vertical round alumina-water nanofluid jet and a horizontal circular round surface is carried out. Different jet flow rates, jet nozzle diameters, various circular disk diameters and three nanoparticles concentrations (0, 6.6 and 10%, respectively) are used. The experimental results indicate that using nanofluid as a heat transfer carrier can enhance the heat transfer process. For the same Reynolds number, the experimental data show an increase in the Nusselt numbers as the nanoparticle concentration increases. Size of heating disk diameters shows reverse effect on heat transfer. It is also found that presenting the data in terms of Reynolds number at impingement jet diameter can take into account on both effects of jet heights and nozzle diameter. Presenting the data in terms of Peclet numbers, at fixed impingement nozzle diameter, makes the data less sensitive to the percentage change of the nanoparticle concentrations. Finally, general heat transfer correlation is obtained verses Peclet numbers using nanoparticle concentrations and the nozzle diameter ratio as parameters. PMID:22340669

  1. Vertical grid of retrieved atmospheric profiles

    NASA Astrophysics Data System (ADS)

    Ceccherini, Simone; Carli, Bruno; Raspollini, Piera

    2016-05-01

    The choice of the vertical grid of atmospheric profiles retrieved from remote sensing observations is discussed considering the two cases of profiles used to represent the results of individual measurements and of profiles used for subsequent data fusion applications. An ozone measurement of the MIPAS instrument is used to assess, for different vertical grids, the quality of the retrieved profiles in terms of profile values, retrieval errors, vertical resolutions and number of degrees of freedom. In the case of individual retrievals no evident advantage is obtained with the use of a grid finer than the one with a reduced number of grid points, which are optimized according to the information content of the observations. Nevertheless, this instrument dependent vertical grid, which seems to extract all the available information, provides very poor results when used for data fusion applications. A loss of about a quarter of the degrees of freedom is observed when the data fusion is made using the instrument dependent vertical grid relative to the data fusion made using a vertical grid optimized for the data fusion product. This result is explained by the analysis of the eigenvalues of the Fisher information matrix and leads to the conclusion that different vertical grids must be adopted when data fusion is the expected application.

  2. Resonant photo-thermal modification of vertical gallium arsenide nanowires studied using Raman spectroscopy.

    PubMed

    Walia, Jaspreet; Boulanger, Jonathan; Dhindsa, Navneet; LaPierre, Ray; Tang, Xiaowu Shirley; Saini, Simarjeet S

    2016-06-17

    Gallium arsenide nanowires have shown considerable promise for use in applications in which the absorption of light is required. When the nanowires are oriented vertically, a considerable amount of light can be absorbed, leading to significant heating effects. Thus, it is important to understand the threshold power densities that vertical GaAs nanowires can support, and how the nanowire morphology is altered under these conditions. Here, resonant photo-thermal modification of vertical GaAs nanowires was studied using both Raman spectroscopy and electron microscopy techniques. Resonant waveguiding, and subsequent absorption of the excited optical mode reduces the irradiance vertical GaAs nanowires can support relative to horizontal ones, by three orders of magnitude before the onset of structural changes occur. A power density of only 20 W mm(-2) was sufficient to induce local heating in the nanowires, resulting in the formation of arsenic species. Upon further increasing the power, a hollow nanowire morphology was realized. These findings are pertinent to all optical applications and spectroscopic measurements involving vertically oriented GaAs nanowires. Understanding the optical absorption limitations, and the effects of exceeding these limitations will help improve the development of all III-V nanowire devices. PMID:27172276

  3. Resonant photo-thermal modification of vertical gallium arsenide nanowires studied using Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Walia, Jaspreet; Boulanger, Jonathan; Dhindsa, Navneet; LaPierre, Ray; (Shirley Tang, Xiaowu; Saini, Simarjeet S.

    2016-06-01

    Gallium arsenide nanowires have shown considerable promise for use in applications in which the absorption of light is required. When the nanowires are oriented vertically, a considerable amount of light can be absorbed, leading to significant heating effects. Thus, it is important to understand the threshold power densities that vertical GaAs nanowires can support, and how the nanowire morphology is altered under these conditions. Here, resonant photo-thermal modification of vertical GaAs nanowires was studied using both Raman spectroscopy and electron microscopy techniques. Resonant waveguiding, and subsequent absorption of the excited optical mode reduces the irradiance vertical GaAs nanowires can support relative to horizontal ones, by three orders of magnitude before the onset of structural changes occur. A power density of only 20 W mm-2 was sufficient to induce local heating in the nanowires, resulting in the formation of arsenic species. Upon further increasing the power, a hollow nanowire morphology was realized. These findings are pertinent to all optical applications and spectroscopic measurements involving vertically oriented GaAs nanowires. Understanding the optical absorption limitations, and the effects of exceeding these limitations will help improve the development of all III-V nanowire devices.

  4. Resonant photo-thermal modification of vertical gallium arsenide nanowires studied using Raman spectroscopy.

    PubMed

    Walia, Jaspreet; Boulanger, Jonathan; Dhindsa, Navneet; LaPierre, Ray; Tang, Xiaowu Shirley; Saini, Simarjeet S

    2016-06-17

    Gallium arsenide nanowires have shown considerable promise for use in applications in which the absorption of light is required. When the nanowires are oriented vertically, a considerable amount of light can be absorbed, leading to significant heating effects. Thus, it is important to understand the threshold power densities that vertical GaAs nanowires can support, and how the nanowire morphology is altered under these conditions. Here, resonant photo-thermal modification of vertical GaAs nanowires was studied using both Raman spectroscopy and electron microscopy techniques. Resonant waveguiding, and subsequent absorption of the excited optical mode reduces the irradiance vertical GaAs nanowires can support relative to horizontal ones, by three orders of magnitude before the onset of structural changes occur. A power density of only 20 W mm(-2) was sufficient to induce local heating in the nanowires, resulting in the formation of arsenic species. Upon further increasing the power, a hollow nanowire morphology was realized. These findings are pertinent to all optical applications and spectroscopic measurements involving vertically oriented GaAs nanowires. Understanding the optical absorption limitations, and the effects of exceeding these limitations will help improve the development of all III-V nanowire devices.

  5. Surface tension profiles in vertical soap films

    NASA Astrophysics Data System (ADS)

    Adami, N.; Caps, H.

    2015-01-01

    Surface tension profiles in vertical soap films are experimentally investigated. Measurements are performed by introducing deformable elastic objets in the films. The shape adopted by those objects once set in the film is related to the surface tension value at a given vertical position by numerically solving the adapted elasticity equations. We show that the observed dependency of the surface tension versus the vertical position is predicted by simple modeling that takes into account the mechanical equilibrium of the films coupled to previous thickness measurements.

  6. Design and analysis of a 5-MW vertical-fluted-tube condenser for geothermal applications

    SciTech Connect

    Llewellyn, G.H.

    1982-03-01

    The design and analysis of an industtial-sized vertical-fluted-tube condenser. The condenser is used to condense superheated isobutane vapor discharged from a power turbine in a geothermal test facility operated for the US Department of Energy. The 5-MW condenser has 1150 coolant tubes in a four-pass configuration with a total heat transfer area of 725 m/sup 2/ (7800 ft/sup 2/). The unit is being tested at the Geothermal Components Test Facility in the Imperial Valley of East Mesa, California. The condenser design is based on previous experimental research work done at the Oak Ridge National Laboratory on condensing refrigerants on a wide variety of single vertical tubes. Condensing film coefficients obtained on the high-performance vertical fluted tubes in condensing refrigerants are as much as seven times greater than those obtained with vertical smooth tubes that have the same diameter and length. The overall heat transfer performance expected from the fluted tube condenser is four to five times the heat transfer obtained from the identical units employing smooth tubes. Fluted tube condensers also have other direct applications in the Ocean Thermal Energy Conversion (OTEC) program in condensing ammonia, in the petroleum industry in condensing light hydrocarbons, and in the air conditioning and refrigeration industry in condensing fluorocarbon vapors.

  7. Heat Pipes

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Bobs Candies, Inc. produces some 24 million pounds of candy a year, much of it 'Christmas candy.' To meet Christmas demand, it must produce year-round. Thousands of cases of candy must be stored a good part of the year in two huge warehouses. The candy is very sensitive to temperature. The warehouses must be maintained at temperatures of 78-80 degrees Fahrenheit with relative humidities of 38- 42 percent. Such precise climate control of enormous buildings can be very expensive. In 1985, energy costs for the single warehouse ran to more than $57,000 for the year. NASA and the Florida Solar Energy Center (FSEC) were adapting heat pipe technology to control humidity in building environments. The heat pipes handle the jobs of precooling and reheating without using energy. The company contacted a FSEC systems engineer and from that contact eventually emerged a cooperative test project to install a heat pipe system at Bobs' warehouses, operate it for a period of time to determine accurately the cost benefits, and gather data applicable to development of future heat pipe systems. Installation was completed in mid-1987 and data collection is still in progress. In 1989, total energy cost for two warehouses, with the heat pipes complementing the air conditioning system was $28,706, and that figures out to a cost reduction.

  8. Vertical Motions of Oceanic Volcanoes

    NASA Astrophysics Data System (ADS)

    Clague, D. A.; Moore, J. G.

    2006-12-01

    lasting a few hundred thousand years as the island migrates over a broad flexural arch related to isostatic compensation of a nearby active volcano. The arch is located about 190±30 km away from the center of volcanic activity and is also related to the rejuvenated volcanic stage on the islands. Reefs on Oahu that are uplifted several tens of m above sea level are the primary evidence for uplift as the islands over-ride the flexural arch. At the other end of the movement spectrum, both in terms of magnitude and length of response, are the rapid uplift and subsidence that occurs as magma is accumulated within or erupted from active submarine volcanoes. These changes are measured in days to years and are of cm to m variation; they are measured using leveling surveys, tiltmeters, EDM and GPS above sea level and pressure gauges and tiltmeters below sea level. Other acoustic techniques to measure such vertical movement are under development. Elsewhere, evidence for subsidence of volcanoes is also widespread, ranging from shallow water carbonates on drowned Cretaceous guyots, to mapped shoreline features, to the presence of subaerially-erupted (degassed) lavas on now submerged volcanoes. Evidence for uplift is more limited, but includes makatea islands with uplifted coral reefs surrounding low volcanic islands. These are formed due to flexural uplift associated with isostatic loading of nearby islands or seamounts. In sum, oceanic volcanoes display a long history of subsidence, rapid at first and then slow, sometimes punctuated by brief periods of uplift due to lithospheric loading by subsequently formed nearby volcanoes.

  9. Evaluation of Generation Mechanism of Vertical Cracks in Top Coat of TBCs During APS Deposition by Laser AE Method

    NASA Astrophysics Data System (ADS)

    Ito, K.; Kuriki, H.; Araki, H.; Kuroda, S.; Enoki, M.

    2015-06-01

    Vertical cracks can be generated in the top coat of thermal barrier coatings (TBCs) deposited by atmospheric plasma spraying (APS). Since they are known to improve the durability of TBCs such as in the case of dense vertically cracked TBC, clarification of the mechanism and the criteria of cracking are very important. In this study, generation of such vertical cracks was monitored during APS process by laser acoustic emission (AE) method, which is an in situ, non-contact, and non-destructive technique. Temperature was also monitored inside and on the surface of a specimen during APS process for estimation of the temperature field in the top coat. Results of the AE and temperature monitoring were combined to evaluate the relationship between cracking and thermal stress in the top coat. Most of the AE events due to the generation of vertical cracks were detected during rapid heating of the surface of the top coat by the heat flux from the torch. It showed that the vertical cracks were induced due to the tensile stress caused by the temperature difference in the top coat from the rapid heating. Furthermore, the estimated critical thermal stress for vertical cracking from the monitoring results was consistent with a previously reported strength of YSZ coating deposited by thermal spray.

  10. Infrared remote sensing of the vertical and horizontal distribution of clouds

    NASA Technical Reports Server (NTRS)

    Chahine, M. T.; Haskins, R. D.

    1982-01-01

    An algorithm has been developed to derive the horizontal and vertical distribution of clouds from the same set of infrared radiance data used to retrieve atmospheric temperature profiles. The method leads to the determination of the vertical atmospheric temperature structure and the cloud distribution simultaneously, providing information on heat sources and sinks, storage rates and transport phenomena in the atmosphere. Experimental verification of this algorithm was obtained using the 15-micron data measured by the NOAA-VTPR temperature sounder. After correcting for water vapor emission, the results show that the cloud cover derived from 15-micron data is less than that obtained from visible data.

  11. Vertical Water Vapor Distribution at Phoenix

    NASA Astrophysics Data System (ADS)

    Tamppari, L. K.; Lemmon, M. T.

    2016-09-01

    The Phoenix SSI camera data along with radiative transfer modeling are used to retrieve the vertical water vapor profile. Preliminary results indicate that water vapor is often confined near the surface.

  12. Vertical Axis Wind Turbine Foundation parameter study

    SciTech Connect

    Lodde, P.F.

    1980-07-01

    The dynamic failure criterion governing the dimensions of prototype Vertical Axis Wind Turbine Foundations is treated as a variable parameter. The resulting change in foundation dimensions and costs is examined.

  13. Vertically stabilized elongated cross-section tokamak

    DOEpatents

    Sheffield, George V.

    1977-01-01

    This invention provides a vertically stabilized, non-circular (minor) cross-section, toroidal plasma column characterized by an external separatrix. To this end, a specific poloidal coil means is added outside a toroidal plasma column containing an endless plasma current in a tokamak to produce a rectangular cross-section plasma column along the equilibrium axis of the plasma column. By elongating the spacing between the poloidal coil means the plasma cross-section is vertically elongated, while maintaining vertical stability, efficiently to increase the poloidal flux in linear proportion to the plasma cross-section height to achieve a much greater plasma volume than could be achieved with the heretofore known round cross-section plasma columns. Also, vertical stability is enhanced over an elliptical cross-section plasma column, and poloidal magnetic divertors are achieved.

  14. Vertical transport and sources in flux models

    SciTech Connect

    Canavan, G.H.

    1997-01-01

    Vertical transport in flux models in examined and shown to reproduce expected limits for densities and fluxes. Disparities with catalog distributions are derived and inverted to find the sources required to rectify them.

  15. 30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    30. BEARING SHOE / VERTICAL / DIAGONAL / UPPER AND LOWER CHORD DETAIL OF DECK TRUSS. VIEW TO NORTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  16. 23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    23. INCLINED END POST / VERTICAL / DIAGONAL / PORTAL BRACING DETAIL. VIEW TO SOUTHEAST. - Abraham Lincoln Memorial Bridge, Spanning Missouri River on Highway 30 between Nebraska & Iowa, Blair, Washington County, NE

  17. Triaxial thermopile array geo-heat-flow sensor

    DOEpatents

    Carrigan, Charles R.; Hardee, Harry C.; Reynolds, Gerald D.; Steinfort, Terry D.

    1992-01-01

    A triaxial thermopile array geothermal heat flow sensor is designed to measure heat flow in three dimensions in a reconstituted or unperturbed subsurface regime. Heat flow can be measured in conductive or permeable convective media. The sensor may be encased in protective pvc tubing and includes a plurality of thermistors and an array of heat flow transducers arranged in a vertical string. The transducers produce voltage proportional to heat flux along the subsurface regime and permit direct measurement of heat flow in the subsurface regime. The presence of the thermistor array permits a comparison to be made between the heat flow estimates obtained from the transducers and heat flow calculated using temperature differences and Fourier's Law. The device is extremely sensitive with an accuracy of less than 0.1 Heat Flow Units (HFU) and may be used for long term readings.

  18. Vertical sounding balloons for long duration flights

    NASA Astrophysics Data System (ADS)

    Malaterre, P.

    1994-02-01

    Vertical soundings in the lower stratosphere are possible on command with an Infrared Montgolfiere, between 16 km and 28 km. Results of simulations are presented. The first test flight of a 7800 cu m Montgolfiere with a relief valve, has been conducted in Arctic area (Spitzbergen, July 1992). The flight of an Infrared Montgolfiere, with full vertical sounding capabilities, is planned for the end of 1993, from Ecuador (South AMERICA).

  19. Vertical sounding balloons for long duration flights

    NASA Astrophysics Data System (ADS)

    Malaterre, P.

    1994-02-01

    Vertical soundings in the lower stratosphere are possible on command with an Infrared Montgolfiere, between 16 km and 28 km. Results of simulations are presented. The first test flight of a 7800 m3 Montgolfiere with a relief valve, has been conducted in Arctic area (Spitzbergen, July 1992). The flight of an Infrared Montgolfiere, with full vertical sounding capabilities, is planned for the end of 1993, from Ecuador (South AMERICA).

  20. HEAT GENERATION

    DOEpatents

    Imhoff, D.H.; Harker, W.H.

    1963-12-01

    Heat is generated by the utilization of high energy neutrons produced as by nuclear reactions between hydrogen isotopes in a blanket zone containing lithium, a neutron moderator, and uranium and/or thorium effective to achieve multtplicatton of the high energy neutron. The rnultiplied and moderated neutrons produced react further with lithium-6 to produce tritium in the blanket. Thermal neutron fissionable materials are also produced and consumed in situ in the blanket zone. The heat produced by the aggregate of the various nuclear reactions is then withdrawn from the blanket zone to be used or otherwise disposed externally. (AEC)

  1. Heat exchanger

    SciTech Connect

    Drury, C.R.

    1988-02-02

    A heat exchanger having primary and secondary conduits in heat-exchanging relationship is described comprising: at least one serpentine tube having parallel sections connected by reverse bends, the serpentine tube constituting one of the conduits; a group of open-ended tubes disposed adjacent to the parallel sections, the open-ended tubes constituting the other of the conduits, and forming a continuous mass of contacting tubes extending between and surrounding the serpentine tube sections; and means securing the mass of tubes together to form a predetermined cross-section of the entirety of the mass of open-ended tubes and tube sections.

  2. Evaporative heat transfer in beds of sensible heat pellets

    SciTech Connect

    Arimilli, R.V.; Moy, C.A.

    1989-03-01

    An experimental study of boiling/evaporative heat transfer from heated spheres in vertical packed beds with downward liquid-vapor flow of Refrigerant-113 was conducted. Surface superheats of 1 to 50{degrees}C, mass flow rates of 1.7 to 5.6 Kg/min, sphere diameters of 1.59 and 2.54 cm, quality (i.e., mass fraction of vapor) of the inlet flow of 0.02 to 1.0, and two surface conditions were considered. Instrumented smooth and rough aluminum spheres were used to measure the heat transfer coefficients under steady state conditions. Heat transfer coefficients were independently determined for each sphere at three values three values of surface superheat. The quantitative results of this extensive experimental study are successfully correlated. The correlation equation for the boiling heat transfer coefficients is presented in terms of a homogeneous model. The correlation may be used in the development of numerical models to simulate the transient thermal performance of packed bed thermal energy storage unit while operating as an evaporator. The boiling of the liquid-vapor flow around the spheres in the packed bed was visually observed with a fiber-optic baroscope and recorded on a videotape. The visualization results showed qualitatively the presence of four distinct flow regimes. One of these occurs under saturated inlet conditions and are referred to as the Low-quality, Medium-quality, and High-quality Regimes. The regimes are discussed in detail in this paper.

  3. [Is the sense of verticality vestibular?].

    PubMed

    Barra, J; Pérennou, D

    2013-06-01

    The vestibular system constitutes an inertial sensor, which detects linear (otoliths) and angular (semicircular canals) accelerations of the head in the three dimensions. The otoliths are specialized in the detection of linear accelerations and can be used by the brain as a "plumb line" coding earth gravity acceleration (direction). This property of otolithic system suggested that the sense of verticality is supported by the vestibular system. The preeminence of vestibular involvement in the sense of verticality stated in the 1900s was progressively supplanted by the notion of internal models of verticality. The internal models of verticality involve rules and properties of integration of vestibular graviception, somaesthesic graviception, and vision. The construction of a mental representation of verticality was mainly modeled as a bottom-up organization integrating visual, somatosensory and vestibular information without any cognitive modulations. Recent studies reported that the construction of internal models of verticality is not an automatic multi-sensory integration process but corresponds to more complex mechanisms including top-down influences such as awareness of body orientation or spatial representations. PMID:23856176

  4. [Is the sense of verticality vestibular?].

    PubMed

    Barra, J; Pérennou, D

    2013-06-01

    The vestibular system constitutes an inertial sensor, which detects linear (otoliths) and angular (semicircular canals) accelerations of the head in the three dimensions. The otoliths are specialized in the detection of linear accelerations and can be used by the brain as a "plumb line" coding earth gravity acceleration (direction). This property of otolithic system suggested that the sense of verticality is supported by the vestibular system. The preeminence of vestibular involvement in the sense of verticality stated in the 1900s was progressively supplanted by the notion of internal models of verticality. The internal models of verticality involve rules and properties of integration of vestibular graviception, somaesthesic graviception, and vision. The construction of a mental representation of verticality was mainly modeled as a bottom-up organization integrating visual, somatosensory and vestibular information without any cognitive modulations. Recent studies reported that the construction of internal models of verticality is not an automatic multi-sensory integration process but corresponds to more complex mechanisms including top-down influences such as awareness of body orientation or spatial representations.

  5. Rate limits in silicon sheet growth - The connections between vertical and horizontal methods

    NASA Technical Reports Server (NTRS)

    Thomas, Paul D.; Brown, Robert A.

    1987-01-01

    Meniscus-defined techniques for the growth of thin silicon sheets fall into two categories: vertical and horizontal growth. The interactions of the temperature field and the crystal shape are analyzed for both methods using two-dimensional finite-element models which include heat transfer and capillarity. Heat transfer in vertical growth systems is dominated by conduction in the melt and the crystal, with almost flat melt/crystal interfaces that are perpendicular to the direction of growth. The high axial temperature gradients characteristic of vertical growth lead to high thermal stresses. The maximum growth rate is also limited by capillarity which can restrict the conduction of heat from the melt into the crystal. In horizontal growth the melt/crystal interface stretches across the surface of the melt pool many times the crystal thickness, and low growth rates are achievable with careful temperature control. With a moderate axial temperature gradient in the sheet a substantial portion of the latent heat conducts along the sheet and the surface of the melt pool becomes supercooled, leading to dendritic growth. The thermal supercooling is surpressed by lowering the axial gradient in the crystal; this configuration is the most desirable for the growth of high quality crystals. An expression derived from scaling analysis relating the growth rate and the crucible temperature is shown to be reliable for horizontal growth.

  6. Infrared heating

    Technology Transfer Automated Retrieval System (TEKTRAN)

    IR heating was first industrially used in the 1930s for automotive curing applications and rapidly became a widely applied technology in the manufacturing industry. Contrarily, a slower pace in the development of IR technologies for processing foods and agricultural products was observed, due to lim...

  7. Heat exchanger

    DOEpatents

    Wolowodiuk, Walter

    1976-01-06

    A heat exchanger of the straight tube type in which different rates of thermal expansion between the straight tubes and the supply pipes furnishing fluid to those tubes do not result in tube failures. The supply pipes each contain a section which is of helical configuration.

  8. Enhancement of natural-convection heat transfer from a horizontal heated plate using grid fins

    SciTech Connect

    Kitamura, Kenzo; Nagae, Naoyuki; Kimura, Fumiyoshi

    1996-01-01

    An enhancement technique was developed for natural-convection heat transfer from a horizontal heated plate. In order to enhance the heat transfer, grid fins made of copper plates were soldered to the copper base plate. These grid fins function not only as an extended surface but also as a heat-transfer promoter. The apparent heat-transfer coefficient of the above enhanced plate were measured and compared with those of a nontreated, smooth plate and a conventional plate with vertical straight fins. It was found that the highest performance is achieved by the present plate. By adopting grid fins with appropriate size and height, the heat-transfer coefficient at the central portion of the present plate is increased by 35% compared to that of the conventional finned plate with the same fin area of fin height.

  9. Method and apparatus for producing tar sand deposits containing conductive layers having little or no vertical communication

    SciTech Connect

    Glandt, C.A.; Vinegar, H.J.; Gardner, J.W.

    1991-10-29

    This patent describes a process for recovering hydrocarbons from hydrocarbon-bearing deposits containing thin highly conductive layers adjacent to at least one hydrocarbon rich zone. It comprises selecting a hydrocarbon-bearing deposit which contains a thin highly conductive layer within the deposit; installing at least one pair of horizontal electrodes spanning the highly conductive layer and dividing the layer into electrically heated and non-electrically heated zones; providing at least one vertical injection well for hot fluid injection into the hydrocarbon rich zone; providing at least one vertical production well for production of hydrocarbons; electrically heating the thin highly conductive layer to form a preheated zone immediately adjacent to the thin highly conductive layer while simultaneously stimulating the wells with steam; injecting the hot fluid into the deposit adjacent to the thin highly conductive layer and within the thin preheated zone to displace the hydrocarbons to the production wells; and recovering hydrocarbons from the production wells. This patent also describes an apparatus for recovering hydrocarbons from tar sand deposits containing highly conductive layers. It comprises at least two pairs of horizontal electrodes which span the highly conductive layer and divide the highly conductive layer into at least two horizontally displaced electrically heated zones separated by non-electrically heated zones; at least one vertical injection well; and at least one vertical production well.

  10. Two-phase flow instabilities in a vertical annular channel

    SciTech Connect

    Babelli, I.; Nair, S.; Ishii, M.

    1995-09-01

    An experimental test facility was built to study two-phase flow instabilities in vertical annular channel with emphasis on downward flow under low pressure and low flow conditions. The specific geometry of the test section is similar to the fuel-target sub-channel of the Savannah River Site (SRS) Mark 22 fuel assembly. Critical Heat Flux (CHF) was observed following flow excursion and flow reversal in the test section. Density wave instability was not recorded in this series of experimental runs. The results of this experimental study show that flow excursion is the dominant instability mode under low flow, low pressure, and down flow conditions. The onset of instability data are plotted on the subcooling-Zuber (phase change) numbers stability plane.

  11. A simple model for the design of vertical tube absorbers

    SciTech Connect

    Patnaik, V.; Perez-Blanco, H.; Ryan, W.A.

    1993-08-01

    The absorption of water vapor in aqueous solutions of lithium bromide is modelled for a falling-film, vertical-tube absorber. The model is based on the solution of three ordinary differential equations to calculate solution bulk and interface concentration and temperature distributions and the coolant temperature distribution. The heat and mass transfer coefficients employed in the equations are extracted from the literature. In this way, the model incorporates recent information on wavy-laminar flows. Under certain conditions, the solution exhibits instabilities in the entrance region of the absorber tube, which are corrected by the introduction of a dampening factor incorporating relevant thermophysical properties. The usefulness of the model for generating absorber performance charts is demonstrated.

  12. Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Horizontal Cross Bracing Detail, Vertical Cross Bracing Detail, Horizontal Cross Bracing Detail, Vertical Cross Bracing-End Detail - Cumberland Covered Bridge, Spanning Mississinewa River, Matthews, Grant County, IN

  13. Vertical and bisection bias in active touch.

    PubMed

    Millar, S; al-Attar, Z

    2000-01-01

    We investigated the conditions that underlie the vertical and bisection illusion in touch, in order to understand the basis of their similarity to visual illusions, and the means of reducing the biases in length perception by active touch. Movement, speed, and spatial reference cues were tested. Movements in scanning L-shapes in ipsilateral and contralateral (across the body midline) table-top space produced significant underestimation of the vertical line with the right hand, but not with the left hand. Right-handed scanning of L-shapes showed no significant bias when the vertical line in the figure was aligned to the body midline, suggesting that spatial cues were involved. The vertical line was overestimated in inverted T-shapes, but underestimated in rotated T-shapes, implicating line bisection. Holding scanning latencies constant reduced the vertical error for inverted T-shapes, but could not explain the bisection bias. Sectioning biases were predicted by the location of junctions on sectioned lines, showing that junction points act as misleading anchor cues for movement extents. The illusion was significantly reduced when reference information was added by instructing subjects to relate two-handed scanning of the figure to an external frame and to body-centred cues. It is argued that disparities in spatial reference (anchor) cues for movement extents are involved in vertical and bisection biases in active touch. The hypothesis that length illusions depend on disparities in spatial reference information can also account for the similarity of the tactile to the visual horizontal-vertical illusion.

  14. Vertical distribution of structural components in corn stover

    DOE PAGESBeta

    Johnson, Jane M. F.; Karlen, Douglas L.; Gresham, Garold L.; Cantrell, Keri B.; Archer, David W.; Wienhold, Brian J.; Varvel, Gary E.; Laird, David A.; Baker, John; Ochsner, Tyson E.; et al

    2014-11-17

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the earmore » averaged 16.3 ± 0.40 MJ kg⁻¹, but with an alkalinity measure of 0.83 g MJ⁻¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha⁻¹, but it would be only 1000 L ha⁻¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.« less

  15. Vertical distribution of structural components in corn stover

    SciTech Connect

    Jane M. F. Johnson; Douglas L. Karlen; Garold L. Gresham; Keri B. Cantrell; David W. Archer; Brian J. Wienhold; Gary E. Varvel; David A. Laird; John Baker; Tyson E. Ochsner; Jeff M. Novak; Ardell D. Halvorson; Francisco Arriaga; David T. Lightle; Amber Hoover; Rachel Emerson; Nancy W. Barbour

    2014-11-01

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the ear averaged 16.3 ± 0.40 MJ kg?¹, but with an alkalinity measure of 0.83 g MJ?¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha?¹, but it would be only 1000 L ha?¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.

  16. Vertical distribution of structural components in corn stover

    SciTech Connect

    Johnson, Jane M. F.; Karlen, Douglas L.; Gresham, Garold L.; Cantrell, Keri B.; Archer, David W.; Wienhold, Brian J.; Varvel, Gary E.; Laird, David A.; Baker, John; Ochsner, Tyson E.; Novak, Jeff M.; Halvorson, Ardell D.; Arriaga, Francisco; Lightle, David T.; Hoover, Amber; Emerson, Rachel; Barbour, Nancy W.

    2014-11-17

    In the United States, corn (Zea mays L.) stover has been targeted for second generation fuel production and other bio-products. Our objective was to characterize sugar and structural composition as a function of vertical distribution of corn stover (leaves and stalk) that was sampled at physiological maturity and about three weeks later from multiple USA locations. A small subset of samples was assessed for thermochemical composition. Concentrations of lignin, glucan, and xylan were about 10% greater at grain harvest than at physiological maturity, but harvestable biomass was about 25% less due to stalk breakage. Gross heating density above the ear averaged 16.3 ± 0.40 MJ kg⁻¹, but with an alkalinity measure of 0.83 g MJ⁻¹, slagging is likely to occur during gasification. Assuming a stover harvest height of 10 cm, the estimated ethanol yield would be >2500 L ha⁻¹, but it would be only 1000 L ha⁻¹ if stover harvest was restricted to the material from above the primary ear. Vertical composition of corn stover is relatively uniform; thus, decision on cutting height may be driven by agronomic, economic and environmental considerations.

  17. Lagrangian temperature and vertical velocity fluctuations due to gravity waves in the lower stratosphere

    NASA Astrophysics Data System (ADS)

    Podglajen, Aurélien; Hertzog, Albert; Plougonven, Riwal; Legras, Bernard

    2016-04-01

    Wave-induced Lagrangian fluctuations of temperature and vertical velocity in the lower stratosphere are quantified using measurements from superpressure balloons (SPBs). Observations recorded every minute along SPB flights allow the whole gravity wave spectrum to be described and provide unprecedented information on both the intrinsic frequency spectrum and the probability distribution function of wave fluctuations. The data set has been collected during two campaigns coordinated by the French Space Agency in 2010, involving 19 balloons over Antarctica and 3 in the deep tropics. In both regions, the vertical velocity distributions depart significantly from a Gaussian behavior. Knowledge on such wave fluctuations is essential for modeling microphysical processes along Lagrangian trajectories. We propose a new simple parameterization that reproduces both the non-Gaussian distribution of vertical velocities (or heating/cooling rates) and their observed intrinsic frequency spectrum.

  18. Thermal analysis of the vertical bridgman semiconductor crystal growth technique. Ph.D. Thesis

    NASA Technical Reports Server (NTRS)

    Jasinski, T. J.

    1982-01-01

    The quality of semiconductor crystals grown by the vertical Bridgman technique is strongly influenced by the axial and radial variations of temperature within the charge. The relationship between the thermal parameters of the vertical Bridgman system and the thermal behavior of the charge are examined. Thermal models are developed which are capable of producing results expressable in analytical form and which can be used without recourse to extensive computer work for the preliminary thermal design of vertical Bridgman crystal growth systems. These models include the effects of thermal coupling between the furnace and the charge, charge translation rate, charge diameter, thickness and thermal conductivity of the confining crucible, thermal conductivity change and liberation of latent heat at the growth interface, and infinite charge length. The hot and cold zone regions, considered to be at spatially uniform temperatures, are separated by a gradient control region which provides added thermal design flexibility for controlling the temperature variations near the growth interface.

  19. Estimates of the seasonal mean vertical velocity fields of the extratropical Northern Hemisphere

    NASA Technical Reports Server (NTRS)

    White, G. H.

    1983-01-01

    Indirect methods are employed to estimate the wintertime and summertime mean vertical velocity fields of the extratropical Northern Hemisphere and intercomparisons are made, together with comparisons with mean seasonal patterns of cloudiness and precipitation. Twice-daily NMC operational analyses produced general circulation statistics for 11 winters and 12 summers, permitting calculation of the seasonal NMC averages for 6 hr forecasts, solution of the omega equation, integration of continuity equation downward from 100 mb, and solution of the thermodynamic energy equation in the absence of diabatic heating. The methods all yielded similar vertical velocity patterns; however, the magnitude of the vertical velocities could not be calculated with great accuracy. Orography was concluded to have less of an effect in summer than in winter, when winds are stronger.

  20. Vertical mixing due to double diffusion in the tropical western Pacific

    NASA Astrophysics Data System (ADS)

    Lee, Chorong; Chang, Kyung-Il; Lee, Jae Hak; Richards, Kelvin J.

    2014-11-01

    This study calculates the vertical diffusivity and the fluxes of heat, salt, and buoyancy due to turbulence and double diffusion based on a 14 day time series of observations of the dissipation rates of turbulent kinetic energy and thermal variance at 0°N, 156°E from 25 October to 18 November 2012. Salt fingering dominates shear-driven turbulence below 100 m. The estimated flux and associated vertical diffusivity due to double diffusion are approximately 1 order of magnitude higher for temperature and density and 2 orders of magnitude higher for salinity compared to values calculated from a turbulence model. Under weak turbulence conditions, the turbulence model significantly underestimates the magnitude of the vertical buoyancy flux with the flux having the wrong sign. Under these conditions, fluxes induced by double-diffusive mixing need to be considered.

  1. Climatology of tropospheric vertical velocity spectra

    NASA Technical Reports Server (NTRS)

    Ecklund, W. L.; Gage, K. S.; Balsley, B. B.; Carter, D. A.

    1986-01-01

    Vertical velocity power spectra obtained from Poker Flat, Alaska; Platteville, Colorado; Rhone Delta, France; and Ponape, East Caroline Islands using 50-MHz clear-air radars with vertical beams are given. The spectra were obtained by analyzing the quietest periods from the one-minute-resolution time series for each site. The lengths of available vertical records ranged from as long as 6 months at Poker Flat to about 1 month at Platteville. The quiet-time vertical velocity spectra are shown. Spectral period ranging from 2 minutes to 4 hours is shown on the abscissa and power spectral density is given on the ordinate. The Brunt-Vaisala (B-V) periods (determined from nearby sounding balloons) are indicated. All spectra (except the one from Platteville) exhibit a peak at periods slightly longer than the B-V period, are flat at longer periods, and fall rapidly at periods less than the B-V period. This behavior is expected for a spectrum of internal waves and is very similar to what is observed in the ocean (Eriksen, 1978). The spectral amplitudes vary by only a factor of 2 or 3 about the mean, and show that under quiet conditions vertical velocity spectra from the troposphere are very similar at widely different locations.

  2. Some vertical lineaments of lip position.

    PubMed

    Peck, S; Peck, L; Kataja, M

    1992-06-01

    This study was performed to elucidate quantitatively upper lip-tooth-jaw relativity in the vertical dimension. Values for five linear dentolabial measurements were generated from male (n = 42) and female (n = 46) reference samples. In addition, three vertical skeletofacial dimensions and two vertical dental dimensions were recorded. A significant sexual dimorphism was found in the vertical lip-tooth-jaw relationship: the upper lip of the female subjects was positioned on average 1.5 mm more superiorly at maximum smile than the upper lip of the male subjects (p less than 0.01). High smile lines appeared to be a female lineament, and low smile lines appeared to be a male lineament. There was a significant sex difference in upper lip length: the male subjects exhibited a longer upper lip than the female subjects (p less than 0.001). The mean difference was 2.2 mm. A similarly significant male-female difference was seen in the skeletal maxillary height measurement: the male sample showed a 2.2 mm mean vertical maxillary increase over the female sample (p less than 0.001). Furthermore, a significant difference was found between the clinical crown height of the maxillary central incisors in the male and female subjects of comparable ages: the male group had longer central incisor crowns (p less than 0.01).

  3. Geothermal heating

    SciTech Connect

    Aureille, M.

    1982-01-01

    The aim of the study is to demonstrate the viability of geothermal heating projects in energy and economic terms and to provide nomograms from which an initial estimate may be made without having to use data-processing facilities. The effect of flow rate and temperature of the geothermal water on drilling and on the network, and the effect of climate on the type of housing are considered.

  4. Long-term evolution of anthropogenic heat fluxes into a subsurface urban heat island.

    PubMed

    Menberg, Kathrin; Blum, Philipp; Schaffitel, Axel; Bayer, Peter

    2013-09-01

    Anthropogenic alterations in urban areas influence the thermal environment causing elevated atmospheric and subsurface temperatures. The subsurface urban heat island effect is observed in several cities. Often shallow urban aquifers exist with thermal anomalies that spread laterally and vertically, resulting in the long-term accumulation of heat. In this study, we develop an analytical heat flux model to investigate possible drivers such as increased ground surface temperatures (GSTs) at artificial surfaces and heat losses from basements of buildings, sewage systems, subsurface district heating networks, and reinjection of thermal wastewater. By modeling the anthropogenic heat flux into the subsurface of the city of Karlsruhe, Germany, in 1977 and 2011, we evaluate long-term trends in the heat flux processes. It revealed that elevated GST and heat loss from basements are dominant factors in the heat anomalies. The average total urban heat flux into the shallow aquifer in Karlsruhe was found to be ∼759 ± 89 mW/m(2) in 1977 and 828 ± 143 mW/m(2) in 2011, which represents an annual energy gain of around 1.0 × 10(15) J. However, the amount of thermal energy originating from the individual heat flux processes has changed significantly over the past three decades.

  5. The vertical structure of upper ocean variability at the Porcupine Abyssal Plain during 2012-2013

    NASA Astrophysics Data System (ADS)

    Damerell, Gillian M.; Heywood, Karen J.; Thompson, Andrew F.; Binetti, Umberto; Kaiser, Jan

    2016-05-01

    This study presents the characterization of variability in temperature, salinity and oxygen concentration, including the vertical structure of the variability, in the upper 1000 m of the ocean over a full year in the northeast Atlantic. Continuously profiling ocean gliders with vertical resolution between 0.5 and 1 m provide more information on temporal variability throughout the water column than time series from moorings with sensors at a limited number of fixed depths. The heat, salt and dissolved oxygen content are quantified at each depth. While the near surface heat content is consistent with the net surface heat flux, heat content of the deeper layers is driven by gyre-scale water mass changes. Below ˜150m, heat and salt content display intraseasonal variability which has not been resolved by previous studies. A mode-1 baroclinic internal tide is detected as a peak in the power spectra of water mass properties. The depth of minimum variability is at ˜415m for both temperature and salinity, but this is a depth of high variability for oxygen concentration. The deep variability is dominated by the intermittent appearance of Mediterranean Water, which shows evidence of filamentation. Susceptibility to salt fingering occurs throughout much of the water column for much of the year. Between about 700-900 m, the water column is susceptible to diffusive layering, particularly when Mediterranean Water is present. This unique ability to resolve both high vertical and temporal variability highlights the importance of intraseasonal variability in upper ocean heat and salt content, variations that may be aliased by traditional observing techniques.

  6. Frontal dynamics in a California Current System shallow front: 2. Mesoscale vertical velocity

    NASA Astrophysics Data System (ADS)

    Pallã S-Sanz, E.; Johnston, T. M. S.; Rudnick, D. L.

    2010-12-01

    This is the second paper investigating the three-dimensional dynamics from two consecutive, quasi-synoptic surveys of a shallow front in the California Current System. The mesoscale vertical velocity (w) is obtained by solving a generalized ω equation using density and horizontal velocity observations. Highly nonlinear dynamics emerge from the ageostrophic forcing terms for w in an adiabatic generalized ω equation. The two main processes driving w are (1) wind-induced cross-frontal ageostrophic circulation (survey 1) and (2) ageostrophic kinematic deformation during frontogenesis (surveys 1 and 2). The horizontally averaged heat fluxes are positive in the whole water column with maxima at ˜50 m, which warms (cools) the upper (lower) water column and upwells (downwells) light (dense) water. Wind-induced currents interact with the front, cooling the upper ocean and creating a divergent potential vorticity (PV) flux at the Ekman layer base which weakens the vertical heat and PV fluxes in survey 1. Vertical velocity extrema reach ˜10 m d-1 in both surveys. A diabatic ω equation is derived, which introduces an important new idea: the relation of the frictional w with the vertical diffusivity of the differential ageostrophic vorticity. This term is not found in the quasi-geostrophic ω equation. By including vertical mixing, ∣w∣ is enhanced by a factor of 2 in the upper ˜100 m and reduced below. This effect is pronounced when the wind blows in the direction of the frontal jet, but it is sensitive to the vertical mixing parameterization.

  7. Geothermal district heating systems

    SciTech Connect

    Budney, G.S.; Childs, F.

    1982-01-01

    Ten district heating demonstration projects and their present status are described. The projects are Klamath County YMCA, Susanville District Heating, Klamath Falls District Heating, Reno Salem Plaza Condominium, El Centro Community Center Heating/Cooling, Haakon School and Business District Heating, St. Mary's Hospital, Diamond Ring Ranch, Pagosa Springs District Heating, and Boise District Heating.

  8. Layer by Layer coatings assembled through dipping, vertical or horizontal spray for cotton flame retardancy.

    PubMed

    Alongi, Jenny; Carosio, Federico; Frache, Alberto; Malucelli, Giulio

    2013-01-30

    Silica-based assemblies have been deposited on cotton fibres through Layer by Layer technique in order to enhance their flame retardant properties. To this aim, three different deposition procedures (namely, dipping, vertical and horizontal sprays) have been considered and compared. The resulting morphologies of the deposited assemblies have been thoroughly investigated by scanning electron microscopy (SEM) and elemental analysis. SEM observations have demonstrated that only the horizontal spray allows obtaining the deposition of a very homogeneous silica coating when compared to vertical spray or dipping. As a consequence, horizontal spray has proved to ensure the best flame resistance, promoting a substantial increase of the total burning time and final residue, as assessed by flammability tests. Furthermore, cone calorimetry measurements have shown a remarkable increase of the time to ignition, and a significant decrease of heat release rate and total heat release for the fabrics treated by horizontal spray. PMID:23218273

  9. Liquid storage tanks under vertical excitation

    SciTech Connect

    Philippacopoulos, A.J.

    1985-01-01

    Until recently, the hydrodynamic effects on liquid storage tanks induced by an earthquake excitation were basically treated for the horizontal component of the earthquake. Recent studies, however, showed that the hydrodynamic effects due to the vertical component of an earthquake may be significant. In these studies the tank is assumed to be fixed at the bottom. This paper is concerned with the hydrodynamic behavior of liquid storage tanks induced by vertical earthquake input excitation. First, the fluid-tank system is treated as a fixed-base system and a simple formula is obtained for the coupled fluid-structure natural frequency. Second, additional interaction effects due to the foundation flexibility on the fluid-tank system are investigated. It is concluded that the foundation flexibility may have a significant effect on the hydrodynamic behavior of the liquid storage tanks under a vertical ground shaking.

  10. Hydraulic induced instability on a vertical service

    NASA Technical Reports Server (NTRS)

    Bosmans, R. F.

    1985-01-01

    The case history contained provides insight toward the mechanical and hydraulic behavior of a vertical pump. It clearly demonstrates the need for measurements on the rotor at or near the impeller area. The results are reported of an analysis on a service water pump. This pump is typical of the water pumps used throughout the power generation industry. Although little is known of the mechanical behavior of vertical pumps because of difficulty in modeling the rotor system, recent developments in the application of submersible proximity transducers have made possible the measurement of pump dynamics under operating conditions. The purpose of this study was to determine the proper selection and installation of vibration-monitoring transducers as well as to measure the effects of imbalance, misalignment, and hydraulics on the performance and reliability of vertical pumps. In addition, the cause of shaft failures on this pump was to be determined.

  11. Vertical equity: weighting outcomes? or establishing procedures?

    PubMed

    Mooney, G; Jan, S

    1997-01-01

    Considerations of equity in the health policy literature have in the main focussed on horizontal equity (the equal treatment of equals) and as a consequence have tended to overlook vertical equity (the unequal, but equitable, treatment of unequals). There is evidence from earlier, if preliminary, work carried out by the authors and a colleague that health care decision makers may well want to embrace concerns for vertical equity in the allocation of health service resources. This paper examines some possibilities for incorporating vertical equity into health care policy through distributive and/or procedural justice. While no firm solutions are offered, it is suggested that the idea of fitting John Broome's notion of 'claims' within a communitarian framework holds promise.

  12. Vertical cable surveys deliver additional seismic data

    SciTech Connect

    1995-12-01

    Texaco and a Norwegian seismic firm have patented a new system for deploying hydrophones on vertical cables for offshore surveys. The system was used in Texaco North Sea UK Ltd.`s Strathspey field during the summer. The new technique was introduced in the article, ``Peaceful use for war technology,`` published in Texaco UK`s Agenda monthly news magazine, October 1995. That article is summarized here. Using technology developed by the US Navy for antisubmarine warfare, the vertical-cable survey relies on hydrophones attached at regular intervals vertically along cables secured to the ocean floor and held taut by a buoy. The shooting vessel fires the airguns in a pattern over a large area on the surface, over and around the cables. The cables are then moved to a new location and the process is repeated, up to six times in the Strathspey application described here.

  13. THE VERTICAL COMPONENT OF THE SUPERGRANULAR MOTION

    SciTech Connect

    Duvall, T. L. Jr.; Birch, A. C.

    2010-12-10

    Supergranules are observed at the solar photosphere as a cellular horizontal flow pattern with flow diverging from cell centers and converging on cell boundaries. Clark and Johnson calculated that mass conservation leads to an expected vertical flow of only 10 m s{sup -1}, which has been difficult to observe. In the present work, Doppler images near the disk center from Michelson Doppler Imager are averaged about locations of cell centers to obtain the necessary signal-to-noise ratio to see the vertical flow. It is found that, for an average over 1100 cell centers, there is a 10 m s{sup -1} upflow at cell center and a 5 m s{sup -1} downflow at the cell boundaries, confirming the previous estimate. The rms vertical flow is 4 m s{sup -1}, smaller than Giovanelli's upper limit of 10 m s{sup -1}.

  14. On The Vertical Speeds Of Airways Traffic

    NASA Astrophysics Data System (ADS)

    Magill, S. A. N.

    Knowledge of the statistics of aircraft vertical speeds is important both for the construction of realistic traffic simulators and for the development of trajectory prediction tools for use in future air traffic control (ATC) systems. This paper reports on the analysis of radar data recordings for nearly 10000 civil flights on airways. Results are presented for the means and spreads of vertical speeds as functions of altitude. Evidence is presented that roughly half of the observed spreads arise from fluctuations within each aircraft's trajectory, as opposed to variation from one aircraft to another. A simple procedure is proposed for simulating vertical speed data which has statistics similar to those obtained from the radar recordings. Some consequences of the results for the development of trajectory prediction tools for use in future ATC systems are discussed. The results suggest that the provision of accurate trajectory prediction tools is not as straightforward as it might at first appear to be.

  15. Vertical vibration analysis for elevator compensating sheave

    NASA Astrophysics Data System (ADS)

    Watanabe, Seiji; Okawa, Takeya; Nakazawa, Daisuke; Fukui, Daiki

    2013-07-01

    Most elevators applied to tall buildings include compensating ropes to satisfy the balanced rope tension between the car and the counter weight. The compensating ropes receive tension by the compensating sheave, which is installed at the bottom space of the elevator shaft. The compensating sheave is only suspended by the compensating ropes, therefore, the sheave can move vertically while the car is traveling. This paper shows the elevator dynamic model to evaluate the vertical motion of the compensating sheave. Especially, behavior in emergency cases, such as brake activation and buffer strike, was investigated to evaluate the maximum upward motion of the sheave. The simulation results were validated by experiments and the most influenced factor for the sheave vertical motion was clarified.

  16. Purification process for vertically aligned carbon nanofibers

    NASA Technical Reports Server (NTRS)

    Nguyen, Cattien V.; Delziet, Lance; Matthews, Kristopher; Chen, Bin; Meyyappan, M.

    2003-01-01

    Individual, free-standing, vertically aligned multiwall carbon nanotubes or nanofibers are ideal for sensor and electrode applications. Our plasma-enhanced chemical vapor deposition techniques for producing free-standing and vertically aligned carbon nanofibers use catalyst particles at the tip of the fiber. Here we present a simple purification process for the removal of iron catalyst particles at the tip of vertically aligned carbon nanofibers derived by plasma-enhanced chemical vapor deposition. The first step involves thermal oxidation in air, at temperatures of 200-400 degrees C, resulting in the physical swelling of the iron particles from the formation of iron oxide. Subsequently, the complete removal of the iron oxide particles is achieved with diluted acid (12% HCl). The purification process appears to be very efficient at removing all of the iron catalyst particles. Electron microscopy images and Raman spectroscopy data indicate that the purification process does not damage the graphitic structure of the nanotubes.

  17. Top-down vertical itemset mining

    NASA Astrophysics Data System (ADS)

    Sohrabi, Mohammad Karim; Ghods, Vahid

    2015-03-01

    Vertical itemset mining is an important frequent pattern mining problem with broad applications. It is challenging since one may need to examine a combinatorial explosive number of possible patterns of items of a dataset in a traditional horizontal algorithm. Since high dimensional datasets typically contain a large number of columns and a small number of rows, vertical itemset mining algorithms, which extract the frequent itemsets of dataset by producing all combination of rows ids, are a good alternative for horizontal algorithms in mining frequent itemsets from high dimensional dataset. Since a rowset can be simply produced from its subsets by adding a new row id to a sub rowset, many bottom up vertical itemset mining algorithms are designed and represented in the literature. However, bottom up vertical mining algorithms suffer from a main drawback. Bottom-up algorithms start the process of generating and testing of rowsets from the small rowsets and go on to the larger rowsets, whereas the small rowsets cannot produce a frequent itemsets because they contain less than minimum support threshold number of rows. In this paper, we described a new efficient vertical top down algorithm called VTD (Vertical Top Down) to conduct mining of frequent itemsets in high dimensional datasets. Our top down approach employed the minimum support threshold to prune the rowsets which any itemset could not be extracted from them. Several experiments on real bioinformatics datasets showed that VTD is orders of magnitude better than previous closed pattern mining algorithms. Our performance study showed that this algorithm outperformed substantially the best former algorithms.

  18. Turbulence in vertical axis wind turbine canopies

    NASA Astrophysics Data System (ADS)

    Kinzel, Matthias; Araya, Daniel B.; Dabiri, John O.

    2015-11-01

    Experimental results from three different full scale arrays of vertical-axis wind turbines (VAWTs) under natural wind conditions are presented. The wind velocities throughout the turbine arrays are measured using a portable meteorological tower with seven, vertically staggered, three-component ultrasonic anemometers. The power output of each turbine is recorded simultaneously. The comparison between the horizontal and vertical energy transport for the different turbine array sizes shows the importance of vertical transport for large array configurations. Quadrant-hole analysis is employed to gain a better understanding of the vertical energy transport at the top of the VAWT arrays. The results show a striking similarity between the flows in the VAWT arrays and the adjustment region of canopies. Namely, an increase in ejections and sweeps and decrease in inward and outward interactions occur inside the turbine array. Ejections are the strongest contributor, which is in agreement with the literature on evolving and sparse canopy flows. The influence of the turbine array size on the power output of the downstream turbines is examined by comparing a streamwise row of four single turbines with square arrays of nine turbine pairs. The results suggest that a new boundary layer forms on top of the larger turbine arrays as the flow adjusts to the new roughness length. This increases the turbulent energy transport over the whole planform area of the turbine array. By contrast, for the four single turbines, the vertical energy transport due to turbulent fluctuations is only increased in the near wake of the turbines. These findings add to the knowledge of energy transport in turbine arrays and therefore the optimization of the turbine spacing in wind farms.

  19. Mixed convection nanofluid flow in a vertical channel with boundary conditions of the third kind

    NASA Astrophysics Data System (ADS)

    Makhatar, Nur Asiah Mohd; Siddheshwar, P. G.; Saleh, Habibis; Hashim, Ishak

    2015-09-01

    A numerical investigation is carried out into the heat transfer within a fully-developed mixed convection flow of Al2O3 - water, CuO - water and TiO2 - water nanoliquids in a vertical channel with boundary condition of third kind. The effects of Brinkman number, Br and mixed convection parameter, GR on the velocity distribution and temperature distribution are the focus of this study. The built-in routine, dsolve in MAPLE is applied for the numerical computation. It was found that, greater value of GR and lower value of Br greatly affected the heat transfer performance and resulted the occurrence of reversal flow.

  20. A numerical study of a vertical solar air collector with obstacle

    NASA Astrophysics Data System (ADS)

    Moumeni, A.; Bouchekima, B.; Lati, M.

    2016-07-01

    Because of the lack of heat exchange obtained by a solar air between the fluid and the absorber, the introduction of obstacles arranged in rows overlapping in the ducts of these systems improves heat transfer. In this work, a numerical study using the finite volume methods is made to model the dynamic and thermal behavior of air flow in a vertical solar collector with baffles destined for integration in building. We search essentially to compare between three air collectors models with different inclined obstacles angle. The first kind with 90° shows a good performance energetic and turbulent.

  1. On the measurement of the thermal impedance in vertical-external-cavity surface-emitting lasers

    NASA Astrophysics Data System (ADS)

    Hader, J.; Wang, T.-L.; Moloney, J. V.; Heinen, B.; Koch, M.; Koch, S. W.; Kunert, B.; Stolz, W.

    2013-04-01

    A detailed and systematic analysis of the loss mechanisms in vertical-external-cavity surface-emitting lasers is presented with the goal to correctly determine the amount of pump power that is converted to heat. With this input, the accuracy of a recently proposed method for measuring the thermal impedance based on roll-over characteristics is shown to be very high for devices with and without dielectric coating. Potential errors arising from non-heating losses can be determined by performing experiments with different out-coupling mirrors.

  2. Correlation of local heat flux from inclined volume-heated pools in bubbly flow

    SciTech Connect

    Greene, G.A.; Abuaf, N.; Jones, O.C. Jr.

    1980-01-01

    Local and average heat transfer from volume-boiling pools in the two-phase bubbly flow regime to vertical and inclined flat boundaries were measured. The experimental technique and newly developed gold electroplated microthermocouples to make the measurements are described. A modification to the Boussinesq approximation for liquids is outlined which includes the effect of the average void fraction in a modified Rayleigh number. Heat transfer to vertical and inclined surfaces is correlated in a fashion similar to natural convection in the bubbly flow regime. These new correlations agreed in general with those based on average heat transfer data obtained by Gabor et al. The data from one reference, however, were found to lie significantly below the present data on an average as well as local basis.

  3. CIRSS vertical data integration, San Bernardino study

    NASA Technical Reports Server (NTRS)

    Hodson, W.; Christenson, J.; Michel, R. (Principal Investigator)

    1982-01-01

    The creation and use of a vertically integrated data base, including LANDSAT data, for local planning purposes in a portion of San Bernardino County, California are described. The project illustrates that a vertically integrated approach can benefit local users, can be used to identify and rectify discrepancies in various data sources, and that the LANDSAT component can be effectively used to identify change, perform initial capability/suitability modeling, update existing data, and refine existing data in a geographic information system. Local analyses were developed which produced data of value to planners in the San Bernardino County Planning Department and the San Bernardino National Forest staff.

  4. Fundamental and effective Yang-Mills vertices

    SciTech Connect

    Hofmann, Ralf

    2012-09-26

    Calorons and plane waves within and in between them collectively give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum of deconfining SU(2) Yang-Mills thermodynamics (dynamical gauge-symmetry breaking). In the present talk we discuss the role of a single caloron in inducing effective local vertices, characterized by powers of h, mediating the interaction of plane waves which propagate over large distances. The constraints on momentum transfers through effective 4-vertices are revisited.

  5. Critique of the vertical gradient of gravity

    NASA Technical Reports Server (NTRS)

    Hammer, Sigmund

    1989-01-01

    Growing interest in high precision studies of the Earth's gravitational field warrant a critical review of precision requirements to yield useful results. Several problems are now under consideration. All of these problems involve, more or less, the precise value of the vertical gradients of gravity. The principle conclusion from this review is that the essential absence of Free Air Vertical Gravity Gradient control and actual values of gravimeter calibrations require serious attention. Large errors in high topography on official published gravity maps also cannot be ignored.

  6. Vertical hydrodynamic focusing in glass microchannels

    PubMed Central

    Lin, Tony A.; Hosoi, A. E.; Ehrlich, Daniel J.

    2009-01-01

    Vertical hydrodynamic focusing in microfluidic devices is investigated through simulation and through direct experimental verification using a confocal microscope and a novel form of stroboscopic imaging. Optimization for microfluidic cytometry of biological cells is examined. By combining multiple crossing junctions, it is possible to confine cells to a single analytic layer of interest. Subtractive flows are investigated as a means to move the analysis layer vertically in the channel and to correct the flatness of this layer. The simulation software (ADINA and Coventor) is shown to accurately capture the complex dependencies of the layer interfaces, which vary strongly with channel geometry and relative flow rates. PMID:19693394

  7. Photochemistry and vertical mixing. [in Uranus atmosphere

    NASA Technical Reports Server (NTRS)

    Atreya, S. K.; Sandel, B. R.; Romani, P. N.

    1991-01-01

    Earth-based observations relevant to the question of photochemistry and vertical mixing are discussed. Phytolysis of methane, the only known photochemically active volatile in the Uranian atmosphere, produces heavier hydrocarbons, the most abundant of which are ethane, acetylene, and the polyacetylenes. Unlike Jupiter and Saturn, these hydrocarbon products condense at the low temperatures prevalent in the middle atmosphere. Contrary to the pre-Voyager notion that the atmosphere of Uranus is remarkable clear, it is found that the aerosols are widely and extensively distributed. Despite its photodestruction, methane remains stable in the Uranian atmosphere. The vertical mixing on Uranus is found to be the least efficient of any of the planetary atmospheres.

  8. 'Heat Dome' Heats Up United States

    MedlinePlus

    ... page: https://medlineplus.gov/news/fullstory_160028.html 'Heat Dome' Heats Up United States Much of the country to ... July 22, 2016 (HealthDay News) -- As a massive "heat dome" stretches across the United States this week, ...

  9. The integrated cryogenic system for the atmospheric vertical interferometric detector on FY-4 satellite

    NASA Astrophysics Data System (ADS)

    Wu, Yinong; Liu, EnGuang; Jiang, Zhenhua; Yang, Baoyu; Mu, Yongbin

    2016-05-01

    The cryogenic system for the atmospheric vertical interferometric detector on FY-4 satellite includes a Stirling cryocooler, a radiant cooler, a cryogenic heat pipe and some flexible thermal links as well. These cryogenic elements were integrated together in order to decrease the background radiation and maximize the sensitivity with high efficiency and high reliability. This paper summarizes the cryogenic integration design, technical challenges, and the results of thermal and performance testing.

  10. Preferential syntheses of semiconducting vertically aligned single-walled carbon nanotubes for direct use in FETs.

    PubMed

    Qu, Liangti; Du, Feng; Dai, Liming

    2008-09-01

    We have combined fast heating with plasma enhanced chemical vapor deposition (PECVD) for preferential growth of semiconducting vertically aligned single-walled carbon nanotubes (VA-SWNTs). Raman spectroscopic estimation indicated a high yield of up to 96% semiconducting SWNTs in the VA-SWNT array. The as-synthesized semiconducting SWNTs can be used directly for fabricating FET devices without the need for any postsynthesis purification or separation. PMID:18665651

  11. Heat pump system

    DOEpatents

    Swenson, Paul F.; Moore, Paul B.

    1979-01-01

    An air heating and cooling system for a building includes an expansion-type refrigeration circuit and a heat engine. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The heat engine includes a heat rejection circuit having a source of rejected heat and a primary heat exchanger connected to the source of rejected heat. The heat rejection circuit also includes an evaporator in heat exchange relation with the primary heat exchanger, a heat engine indoor heat exchanger, and a heat engine outdoor heat exchanger. The indoor heat exchangers are disposed in series air flow relationship, with the heat engine indoor heat exchanger being disposed downstream from the refrigeration circuit indoor heat exchanger. The outdoor heat exchangers are also disposed in series air flow relationship, with the heat engine outdoor heat exchanger disposed downstream from the refrigeration circuit outdoor heat exchanger. A common fluid is used in both of the indoor heat exchangers and in both of the outdoor heat exchangers. In a first embodiment, the heat engine is a Rankine cycle engine. In a second embodiment, the heat engine is a non-Rankine cycle engine.

  12. Heat pump system

    DOEpatents

    Swenson, Paul F.; Moore, Paul B.

    1982-01-01

    An air heating and cooling system for a building includes an expansion-type refrigeration circuit and a heat engine. The refrigeration circuit includes two heat exchangers, one of which is communicated with a source of indoor air from the building and the other of which is communicated with a source of air from outside the building. The heat engine includes a heat rejection circuit having a source of rejected heat and a primary heat exchanger connected to the source of rejected heat. The heat rejection circuit also includes an evaporator in heat exchange relation with the primary heat exchanger, a heat engine indoor heat exchanger, and a heat engine outdoor heat exchanger. The indoor heat exchangers are disposed in series air flow relationship, with the heat engine indoor heat exchanger being disposed downstream from the refrigeration circuit indoor heat exchanger. The outdoor heat exchangers are also disposed in series air flow relationship, with the heat engine outdoor heat exchanger disposed downstream from the refrigeration circuit outdoor heat exchanger. A common fluid is used in both of the indoor heat exchanges and in both of the outdoor heat exchangers. In a first embodiment, the heat engine is a Rankine cycle engine. In a second embodiment, the heat engine is a non-Rankine cycle engine.

  13. Asymmetrical vertical phorias indicating dissociated vertical deviation in subjects with normal binocular vision.

    PubMed

    van Rijn, L J; ten Tusscher, M P; de Jong, I; Hendrikse, F

    1998-10-01

    We measured the symmetry of phoria angles in six normal subjects. Subjects were selected on the basis of good visual acuity and stereopsis, normal binocular eye alignment and, apart from mild refraction errors, absence of ocular abnormalities. They were instructed to look at a word on a reading chart at 2 m distance. Each measurement consisted of five subsequent intervals of 5 s duration. During these five intervals viewing was binocular, with the right eye only, binocular, with the left eye only, and binocular, respectively. Each experiment consisted of twelve measurements. Eye movements were measured with scleral coils suited for measuring in horizontal, vertical and torsional directions. Five out of six subjects displayed an asymmetrical vertical phoria; one subject showed an alternating hyperphoria; four displayed a left over right vertical phoria that was largest for left eye occlusion. Only one subject showed a symmetrical vertical phoria. Both the size of the vertical phorias and the size of the asymmetries in these vertical phorias were very small: on average 0.16 +/- 0.01 and 0.17 +/- 0.01 degree, respectively. The direction of the vertical phoria asymmetries (the largest left over right was found with left eye occlusion) and the fact that asymmetries were found more often in vertical than horizontal and torsional phorias suggest that these asymmetries are related to dissociated vertical deviation. These results suggest that dissociated vertical deviation, often observed in subjects with a disruption of binocular vision early in life, reflects the enhancement of a phenomenon that is present in normal subjects as well.

  14. Analysis of tropical radiative heating profiles: A comparison of models and observations

    SciTech Connect

    McFarlane, Sally A.; Mather, Jim H.; Ackerman, Thomas P.

    2007-07-31

    Vertical distribution of radiative heating in the atmosphere is an important driver of atmospheric circulation, especially in the tropics. Evaluation of model simulations of the Earth's radiation balance typically focus on performance at the top of the atmosphere or at the surface. This study compares the vertical distribution of clouds and radiative heating rates calculated from observations at the Department of Energy's Atmospheric Radiation Measurement (ARM) sites on the islands of Nauru and Manus to simulations performed using the Multiscale Modeling Framework (MMF) and the Community Atmosphere Model (CAM). There are significant differences between the model vertical profiles of cloud properties and radiative heating and those calculated from the ARM observations. The MMF simulation results in better representation of the observed variability in ice cloud condensed water content and resulting upper tropospheric radiative heating rates than the CAM; more realistic diurnal variability in the radiative heating profiles; and a significantly lower level of zero net radiative heating.

  15. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 1 2014-07-01 2014-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  16. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 1 2012-07-01 2012-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  17. 33 CFR 118.85 - Lights on vertical lift bridges.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 33 Navigation and Navigable Waters 1 2013-07-01 2013-07-01 false Lights on vertical lift bridges... BRIDGES BRIDGE LIGHTING AND OTHER SIGNALS § 118.85 Lights on vertical lift bridges. (a) Lift span lights. The vertical lift span of every vertical lift bridge shall be lighted so that the center of...

  18. 46 CFR 190.10-15 - Vertical ladders not accepted.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 7 2011-10-01 2011-10-01 false Vertical ladders not accepted. 190.10-15 Section 190.10... CONSTRUCTION AND ARRANGEMENT Means of Escape § 190.10-15 Vertical ladders not accepted. (a) Vertical ladders... vertical ladder may be used as the second means of escape....

  19. 46 CFR 190.10-15 - Vertical ladders not accepted.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 7 2010-10-01 2010-10-01 false Vertical ladders not accepted. 190.10-15 Section 190.10... CONSTRUCTION AND ARRANGEMENT Means of Escape § 190.10-15 Vertical ladders not accepted. (a) Vertical ladders... vertical ladder may be used as the second means of escape....

  20. On the measurement of vertical velocity by MST radar

    NASA Technical Reports Server (NTRS)

    Gage, K. S.

    1983-01-01

    An overview is presented of the measurement of atmospheric vertical motion utilizing the MST radar technique. Vertical motion in the atmosphere is briefly discussed as a function of scale. Vertical velocity measurement by MST radars is then considered from within the context of the expected magnitudes to be observed. Examples are drawn from published vertical velocity observations.

  1. Growth of vertically aligned multiwall carbon nanotubes columns

    NASA Astrophysics Data System (ADS)

    Shahzad, M. I.; Giorcelli, M.; Perrone, D.; Virga, A.; Shahzad, N.; Jagdale, P.; Cocuzza, M.; Tagliaferro, A.

    2013-06-01

    Capability of patterning carbon nanotubes (CNTs) growth is of tantamount importance for a number of applications ranging from thermal to electronic. This article reports on the columnar growth of vertically aligned multiwall carbon nanotubes (VA-MWCNTs) on patterned Silicon (Si) surface. We have developed procedures based on negative as well as positive masking approaches which allows the growth of predetermined MWCNTs patterns. We describe in detail the process steps leading to Si surface patterning. As quoted above, patterns are exploited to grow VA-MWCNTs. We have focused in particular on the growth of CNT pillars by chemical vapor despoition (CVD) technique at 850°C with camphor and ferrocene as carbon precursors and catalyst respectively. Field emission scanning electron microscopy (FESEM) is employed at low magnification to verify the correct patterning, and at high magnification to examine the surface morphology of CNTs pillars. The pillars are up to 2 mm high, their height being tailored through the deposition time. The diameter of each MWCNT is in the range 30-70 nm and the length is up to few hundred micrometers. The small CNT pillars produced, have several electrical and thermal applications. For instance they can be very useful for heat transfer systems as the lower thermal conductivity of fluids can be improved by the inclusion of nanotubes thanks to their peculiar 1-dimensional heat transfer characteristics.

  2. Enhanced photothermal conversion in vertically oriented gallium arsenide nanowire arrays.

    PubMed

    Walia, Jaspreet; Dhindsa, Navneet; Flannery, Jeremy; Khodabad, Iman; Forrest, James; LaPierre, Ray; Saini, Simarjeet S

    2014-10-01

    The photothermal properties of vertically etched gallium arsenide nanowire arrays are examined using Raman spectroscopy. The nanowires are arranged in square lattices with a constant pitch of 400 nm and diameters ranging from 50 to 155 nm. The arrays were illuminated using a 532 nm laser with an incident energy density of 10 W/mm(2). Nanowire temperatures were highly dependent on the nanowire diameter and were determined by measuring the spectral red-shift for both TO and LO phonons. The highest temperatures were observed for 95 nm diameter nanowires, whose top facets and sidewalls heated up to 600 and 440 K, respectively, and decreased significantly for the smaller or larger diameters studied. The diameter-dependent heating is explained by resonant coupling of the incident laser light into optical modes of the nanowires, resulting in increased absorption. Photothermal activity in a given nanowire diameter can be optimized by proper wavelength selection, as confirmed using computer simulations. This demonstrates that the photothermal properties of GaAs nanowires can be enhanced and tuned by using a photonic lattice structure and that smaller nanowire diameters are not necessarily better to achieve efficient photothermal conversion. The diameter and wavelength dependence of the optical coupling could allow for localized temperature gradients by creating arrays which consist of different diameters.

  3. Thermal Conduction in Vertically Aligned Copper Nanowire Arrays and Composites.

    PubMed

    Barako, Michael T; Roy-Panzer, Shilpi; English, Timothy S; Kodama, Takashi; Asheghi, Mehdi; Kenny, Thomas W; Goodson, Kenneth E

    2015-09-01

    The ability to efficiently and reliably transfer heat between sources and sinks is often a bottleneck in the thermal management of modern energy conversion technologies ranging from microelectronics to thermoelectric power generation. These interfaces contribute parasitic thermal resistances that reduce device performance and are subjected to thermomechanical stresses that degrade device lifetime. Dense arrays of vertically aligned metal nanowires (NWs) offer the unique combination of thermal conductance from the constituent metal and mechanical compliance from the high aspect ratio geometry to increase interfacial heat transfer and device reliability. In the present work, we synthesize copper NW arrays directly onto substrates via templated electrodeposition and extend this technique through the use of a sacrificial overplating layer to achieve improved uniformity. Furthermore, we infiltrate the array with an organic phase change material and demonstrate the preservation of thermal properties. We use the 3ω method to measure the axial thermal conductivity of freestanding copper NW arrays to be as high as 70 W m(-1) K(-1), which is more than an order of magnitude larger than most commercial interface materials and enhanced-conductivity nanocomposites reported in the literature. These arrays are highly anisotropic, and the lateral thermal conductivity is found to be only 1-2 W m(-1) K(-1). We use these measured properties to elucidate the governing array-scale transport mechanisms, which include the effects of morphology and energy carrier scattering from size effects and grain boundaries. PMID:26284489

  4. Thermal Conduction in Vertically Aligned Copper Nanowire Arrays and Composites.

    PubMed

    Barako, Michael T; Roy-Panzer, Shilpi; English, Timothy S; Kodama, Takashi; Asheghi, Mehdi; Kenny, Thomas W; Goodson, Kenneth E

    2015-09-01

    The ability to efficiently and reliably transfer heat between sources and sinks is often a bottleneck in the thermal management of modern energy conversion technologies ranging from microelectronics to thermoelectric power generation. These interfaces contribute parasitic thermal resistances that reduce device performance and are subjected to thermomechanical stresses that degrade device lifetime. Dense arrays of vertically aligned metal nanowires (NWs) offer the unique combination of thermal conductance from the constituent metal and mechanical compliance from the high aspect ratio geometry to increase interfacial heat transfer and device reliability. In the present work, we synthesize copper NW arrays directly onto substrates via templated electrodeposition and extend this technique through the use of a sacrificial overplating layer to achieve improved uniformity. Furthermore, we infiltrate the array with an organic phase change material and demonstrate the preservation of thermal properties. We use the 3ω method to measure the axial thermal conductivity of freestanding copper NW arrays to be as high as 70 W m(-1) K(-1), which is more than an order of magnitude larger than most commercial interface materials and enhanced-conductivity nanocomposites reported in the literature. These arrays are highly anisotropic, and the lateral thermal conductivity is found to be only 1-2 W m(-1) K(-1). We use these measured properties to elucidate the governing array-scale transport mechanisms, which include the effects of morphology and energy carrier scattering from size effects and grain boundaries.

  5. Hydride heat pump with heat regenerator

    NASA Technical Reports Server (NTRS)

    Jones, Jack A. (Inventor)

    1991-01-01

    A regenerative hydride heat pump process and system is provided which can regenerate a high percentage of the sensible heat of the system. A series of at least four canisters containing a lower temperature performing hydride and a series of at least four canisters containing a higher temperature performing hydride is provided. Each canister contains a heat conductive passageway through which a heat transfer fluid is circulated so that sensible heat is regenerated. The process and system are useful for air conditioning rooms, providing room heat in the winter or for hot water heating throughout the year, and, in general, for pumping heat from a lower temperature to a higher temperature.

  6. Heating systems for heating subsurface formations

    SciTech Connect

    Nguyen, Scott Vinh; Vinegar, Harold J.

    2011-04-26

    Methods and systems for heating a subsurface formation are described herein. A heating system for a subsurface formation includes a sealed conduit positioned in an opening in the formation and a heat source. The sealed conduit includes a heat transfer fluid. The heat source provides heat to a portion of the sealed conduit to change phase of the heat transfer fluid from a liquid to a vapor. The vapor in the sealed conduit rises in the sealed conduit, condenses to transfer heat to the formation and returns to the conduit portion as a liquid.

  7. Heat pipe waste heat recovery boilers

    NASA Astrophysics Data System (ADS)

    Littwin, D. A.; McCurley, J.

    The use of heat pipes as transport devices in waste heat recovery boilers is examined. Test results show that heat pipes can efficiently extract heat from the hot gas stream and transfer it inside the pressure vessel for the steam generation process. The benefits of incorporating heat pipes into the design of waste heat recovery boilers include a highly compact package, a significant reduction in thermally induced stresses, double isolation of the steam from the heat source, an extended surface for improved efficiency in heat extraction, improved circulation and stability in the boiling regime, easy cleaning, individually replaceable tubes, and low flue gas pressure drop.

  8. Vertical group III-V nanowires on si, heterostructures, flexible arrays and fabrication

    DOEpatents

    Wang, Deli; Soci, Cesare; Bao, Xinyu; Wei, Wei; Jing, Yi; Sun, Ke

    2015-01-13

    Embodiments of the invention provide a method for direct heteroepitaxial growth of vertical III-V semiconductor nanowires on a silicon substrate. The silicon substrate is etched to substantially completely remove native oxide. It is promptly placed in a reaction chamber. The substrate is heated and maintained at a growth temperature. Group III-V precursors are flowed for a growth time. Preferred embodiment vertical Group III-V nanowires on silicon have a core-shell structure, which provides a radial homojunction or heterojunction. A doped nanowire core is surrounded by a shell with complementary doping. Such can provide high optical absorption due to the long optical path in the axial direction of the vertical nanowires, while reducing considerably the distance over which carriers must diffuse before being collected in the radial direction. Alloy composition can also be varied. Radial and axial homojunctions and heterojunctions can be realized. Embodiments provide for flexible Group III-V nanowire structures. An array of Group III-V nanowire structures is embedded in polymer. A fabrication method forms the vertical nanowires on a substrate, e.g., a silicon substrate. Preferably, the nanowires are formed by the preferred methods for fabrication of Group III-V nanowires on silicon. Devices can be formed with core/shell and core/multi-shell nanowires and the devices are released from the substrate upon which the nanowires were formed to create a flexible structure that includes an array of vertical nanowires embedded in polymer.

  9. Oblique patterned etching of vertical silicon sidewalls

    DOE PAGESBeta

    Burckel, D. Bruce; Finnegan, Patrick S.; Henry, M. David; Resnick, Paul J.; Jarecki, Jr., Robert L.

    2016-04-05

    A method for patterning on vertical silicon surfaces in high aspect ratio silicontopography is presented. A Faraday cage is used to direct energetic reactive ions obliquely through a patterned suspended membrane positioned over the topography. The technique is capable of forming high-fidelity pattern (100 nm) features, adding an additional fabrication capability to standard top-down fabrication approaches.

  10. Vertical root fractures and their management

    PubMed Central

    Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

    2014-01-01

    Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

  11. Hinged-Blade, Vertical-Shaft Windmill

    NASA Technical Reports Server (NTRS)

    Shultz, B., Jr.

    1985-01-01

    Vertical-shaft windmill concept calls for hinged, flapping blades to increase energy-conversion efficiency by reducing wind-energy loss. Hinged Blade Halves unfold to catch wind when moving with it, then fold away from wind when moving against it.

  12. Modeling vertical coral connectivity and mesophotic refugia

    NASA Astrophysics Data System (ADS)

    Holstein, Daniel M.; Paris, Claire B.; Vaz, Ana C.; Smith, Tyler B.

    2016-03-01

    Whether mesophotic reefs will behave as refugia for corals threatened by global climate change and coastal development depends on vertical exchange of larvae between diverse habitats. Here we use a biophysical model of larval dispersal to estimate vertical connectivity of a broadcasting ( Orbicella faveolata) and a brooding ( Porites astreoides) species of coral in the US Virgin Islands. Modeling predicts subsidy to shallow areas by mesophotic larvae of both species based on local hydrology, adult reproductive characteristics, larval traits, and a wide range of scenarios developed to test depth-sensitive factors, such as fertilization rates and post-settlement survivorship. In extreme model scenarios of reduced fertilization and post-settlement survivorship of mesophotic larvae, 1-10 % local mesophotic subsidy to shallow recruitment is predicted for both species, which are demographically significant. Although direct vertical connectivity is higher for the broadcaster, the brooder demonstrates higher local multigenerational vertical connectivity, which suggests that local P. astreoides populations are more resilient than those of O. faveolata, and corroborates field studies. As shallow habitat degrades, mesophotic-shallow subsidy is predicted to increase for both species. This study is the first of its kind to simulate larval dispersal and settlement between habitats of different depths, and these findings have local, regional, and global implications for predicting and managing coral reef persistence in a changing climate.

  13. Vertical motions in the equatorial middle atmosphere

    NASA Technical Reports Server (NTRS)

    Weisman, M. L.

    1979-01-01

    A single station vertical velocity equation which considers ageostrophic and diabatic effects derived from the first law of thermodynamics and a generalized thermal wind relation is presented. An analysis and verification procedure which accounts for measurement and calculation errors as well as time and space continuity arguments and theoretical predictions are described. Vertical velocities are calculated at every kilometer between 25 and 60 km and for approximately every three hours for the above diurnal period at Kourou (French Guiana), Fort Sherman (Panama Canal Zone), Ascension Island, Antigua (British West Indies) and Natal (Brazil). The results, plotted as time series cross sections, suggest vertical motions ranging in magnitude from 1 or 2 cm/sec at 30 km to as much as 15 cm/sec at 60 km. Many of the general features of the results agree well with atmospheric tidal predictions but many particular features suggest that both smaller time scale gravity waves (periods less than 6 hours) and synoptic type waves (periods greater than 1 day) may be interacting significantly with the tidal fields. The results suggest that vertical motions can be calculated for the equatorial middle atmosphere and must be considered a significant part of the motion for time scales from 8 to 24 hours.

  14. A Simple Vertical Slab Gel Electrophoresis Apparatus.

    ERIC Educational Resources Information Center

    Carter, J. B.; And Others

    1983-01-01

    Describes an inexpensive, easily constructed, and safe vertical slab gel kit used routinely for sodium dodecyl sulphate-polyacrylamide gel electrophoresis research and student experiments. Five kits are run from a single transformer. Because toxic solutions are used, students are given plastic gloves and closely supervised during laboratory…

  15. Vertical Alveolar Ridge Augmentation by Distraction Osteogenesis

    PubMed Central

    Kumar, N. Nanda; Ravindran, C.

    2015-01-01

    Introduction Compromised alveolar ridge in vertical and horizontal dimension is a common finding in patients visiting practitioners for dental prosthesis. Various treatment modalities are available for correction of deficient ridges among which alveolar distraction osteogenesis is one. Aim To study the efficacy of alveolar distraction osteogenesis in augmentation of alveolar ridges deficient in vertical dimension. Materials and Methods Ten patients aged 16 to 46 years with deficient alveolar ridge underwent ridge augmentation in 11 alveolar segments using the distraction osteogenesis method. For each patient a custom made distraction device was fabricated. The device was indigenously manufactured with SS-316 (ISO 3506). Results The vertical bone gain reached more than 10mm without the use of bone transplantation. Certain complications like incorrect vector of distraction, paresthesia, pain and loss of transport segment were encountered during the course of the study. Conclusion Alveolar vertical distraction osteogenesis is a reliable and predictable technique for both hard and soft tissue genesis. Implant placement is feasible with primary stability in neogenerated bone at the level of the distracted areas. PMID:26816991

  16. Vertical File Subject Headings KWIK List.

    ERIC Educational Resources Information Center

    Knowles, Em Claire; And Others

    A subject heading keyword-in-context (KWIK) list for the vertical files at the University of California, Davis, is presented. It is noted that the KWIK list was prepared to assist library users in locating more subject headings for available materials in the various pamphlet collections and that the list is computerized to enable frequent…

  17. Oblique patterned etching of vertical silicon sidewalls

    NASA Astrophysics Data System (ADS)

    Bruce Burckel, D.; Finnegan, Patrick S.; David Henry, M.; Resnick, Paul J.; Jarecki, Robert L.

    2016-04-01

    A method for patterning on vertical silicon surfaces in high aspect ratio silicon topography is presented. A Faraday cage is used to direct energetic reactive ions obliquely through a patterned suspended membrane positioned over the topography. The technique is capable of forming high-fidelity pattern (100 nm) features, adding an additional fabrication capability to standard top-down fabrication approaches.

  18. Vertical Integration Spurs American Health Care Revolution.

    ERIC Educational Resources Information Center

    Phillips, Richard C.

    1986-01-01

    Under new "managed health care systems," the classical functional separation of risk taker, claims payor, and provider are vertically integrated into a common entity. This evolution should produce a competitive environment with medical care rendered to all Americans on a more cost-effective basis. (CJH)

  19. Vertical Integration: Teachers' Knowledge and Teachers' Voice.

    ERIC Educational Resources Information Center

    Corrie, L.

    1995-01-01

    Traces the theoretical basis for vertical integration in early school years. Contrasts transmission-based pedagogy with a higher level of teacher control, and acquirer-based pedagogy with a higher level of student control. Suggests that early childhood pedagogy will be maintained when teachers are able to articulate their pedagogical knowledge and…

  20. Vertical Arc for ILC Low Emittance Transport

    SciTech Connect

    Tenenbaum, P.; Woodley, M.; /SLAC

    2005-06-07

    The design and parameters of a vertical arc for the ILC Low Emittance Transport (LET) are reviewed. A 1 TeV CM ILC which relies upon 30 MV/m accelerating cavities with a packing fraction of 65% will require almost 48 km of main linac, which suggests that the total site length including BDS and bunch compressors will be on the order of 53 km. If built in a laser-straight tunnel with the low-energy ends near the surface, and assuming a perfectly spherical ''cue ball'' planetary surface with radius 6370 km, the collider halls will necessarily be 55 meters below grade, as shown in the top plot of Figure 1. Such depths would demand extensive use of deep tunneling, which would potentially drive up the cost and difficulty of ILC construction. An alternate solution is to use discrete vertical arcs at a few locations to allow a ''piecewise straight'' construction in which the depth of the tunnel below grade does not vary by more than a few meters. This approach is shown schematically in the bottom plot of Figure 1. In this Note we consider the issues for a design with one such vertical arc at the 250 GeV/c point (ie, midway down the linac for 1 TeV CM), and a second arc at the entrance to the BDS (ie, the entire BDS lies in one plane, with vertical arcs at each end).

  1. Viewing Vertical Objects with an Overhead Projector.

    ERIC Educational Resources Information Center

    Wild, R. L.

    1988-01-01

    Discusses the use of an overhead projector for the deflection of a vertical image to a screen. Describes three demonstrations: magnetizing of a steel ball bearing and paper clip; convection currents of a hot liquid within a cold liquid; and oscillation of concentrated salt solution into fresh water. (YP)

  2. Leak-tight vertical membrane microvalves.

    PubMed

    Hansson, Jonas; Hillmering, Mikael; Haraldsson, Tommy; van der Wijngaart, Wouter

    2016-04-21

    Pneumatic microvalves are fundamental control components in a large range of microfluidic applications. Their key performance parameters are small size, i.e. occupying a minimum of microfluidic real estate, low flow resistance in the open state, and leak-tight closing at limited control pressures. In this work we present the successful design, realization and evaluation of the first leak-tight, vertical membrane, pneumatic microvalves. The realization of the vertical membrane microvalves is enabled by a novel dual-sided molding method for microstructuring monolithic 3D microfluidic networks in PDMS in a single step, eliminating the need for layer-to-layer alignment during bonding. We demonstrate minimum lateral device features down to 20-30 μm in size, and vertical via density of ∼30 000 per cm(2), which provides significant gains in chip real estate compared to previously reported PDMS manufacturing methods. In contrast to horizontal membrane microvalves, there are no manufacturing restrictions on the cross-sectional geometry of the flow channel of the vertical membrane microvalves. This allows tuning the design towards lower closing pressure or lower open state flow resistance compared to those of horizontal membrane microvalves. PMID:26983557

  3. Electrostatic comb drive for vertical actuation

    SciTech Connect

    Lee, A. P., LLNL

    1997-07-10

    The electrostatic comb finger drive has become an integral design for microsensor and microactuator applications. This paper reports on utilizing the levitation effect of comb fingers to design vertical-to-the-substrate actuation for interferometric applications. For typical polysilicon comb drives with 2 {micro}m gaps between the stationary and moving fingers, as well as between the microstructures and the substrate, the equilibrium position is nominally 1-2 {micro}m above the stationary comb fingers. This distance is ideal for many phase shifting interferometric applications. Theoretical calculations of the vertical actuation characteristics are compared with the experimental results, and a general design guideline is derived from these results. The suspension flexure stiffnesses, gravity forces, squeeze film damping, and comb finger thicknesses are parameters investigated which affect the displacement curve of the vertical microactuator. By designing a parallel plate capacitor between the suspended mass and the substrate, in situ position sensing can be used to control the vertical movement, providing a total feedback-controlled system. Fundamentals of various capacitive position sensing techniques are discussed. Experimental verification is carried out by a Zygo distance measurement interferometer.

  4. [From vertical to horizontal. Writing in adolescence].

    PubMed

    Catheline-Antipoff, N

    1995-04-01

    Writing at adolescence has a non negligible part in identity's construction. Vertical writing as tags, graphs and graffiti refer to a narcissism deficiency and express a pulsional necessity, whereas, horizontal writing as private diaries, letters and novels express object's search and are made in dreaming attitude.

  5. Vertical pump with free floating check valve

    DOEpatents

    Lindsay, Malcolm

    1980-01-01

    A vertical pump with a bottom discharge having a free floating check valve isposed in the outlet plenum thereof. The free floating check valve comprises a spherical member with a hemispherical cage-like member attached thereto which is capable of allowing forward or reverse flow under appropriate conditions while preventing reverse flow under inappropriate conditions.

  6. Vertical root fractures and their management.

    PubMed

    Khasnis, Sandhya Anand; Kidiyoor, Krishnamurthy Haridas; Patil, Anand Basavaraj; Kenganal, Smita Basavaraj

    2014-03-01

    Vertical root fractures associated with endodontically treated teeth and less commonly in vital teeth represent one of the most difficult clinical problems to diagnose and treat. In as much as there are no specific symptoms, diagnosis can be difficult. Clinical detection of this condition by endodontists is becoming more frequent, where as it is rather underestimated by the general practitioners. Since, vertical root fractures almost exclusively involve endodontically treated teeth; it often becomes difficult to differentiate a tooth with this condition from an endodontically failed one or one with concomitant periodontal involvement. Also, a tooth diagnosed for vertical root fracture is usually extracted, though attempts to reunite fractured root have been done in various studies with varying success rates. Early detection of a fractured root and extraction of the tooth maintain the integrity of alveolar bone for placement of an implant. Cone beam computed tomography has been shown to be very accurate in this regard. This article focuses on the diagnostic and treatment strategies, and discusses about predisposing factors which can be useful in the prevention of vertical root fractures. PMID:24778502

  7. Vertically aligned biaxially textured molybdenum thin films

    SciTech Connect

    Krishnan, Rahul; Riley, Michael; Lee, Sabrina; Lu, Toh-Ming

    2011-09-15

    Vertically aligned, biaxially textured molybdenum nanorods were deposited using dc magnetron sputtering with glancing flux incidence (alpha = 85 degrees with respect to the substrate normal) and a two-step substrate-rotation mode. These nanorods were identified with a body-centered cubic crystal structure. The formation of a vertically aligned biaxial texture with a [110] out-of-plane orientation was combined with a [-110] in-plane orientation. The kinetics of the growth process was found to be highly sensitive to an optimum rest time of 35 seconds for the two-step substrate rotation mode. At all other rest times, the nanorods possessed two separate biaxial textures each tilted toward one flux direction. While the in-plane texture for the vertical nanorods maintains maximum flux capture area, inclined Mo nanorods deposited at alpha = 85 degrees without substrate rotation display a [-1-1-4] in-plane texture that does not comply with the maximum flux capture area argument. Finally, an in situ capping film was deposited with normal flux incidence over the biaxially textured vertical nanorods resulting in a thin film over the porous nanorods. This capping film possessed the same biaxial texture as the nanorods and could serve as an effective substrate for the epitaxial growth of other functional materials.

  8. Vertically Moderated Standards: Background, Assumptions, and Practices

    ERIC Educational Resources Information Center

    Huynh, Huynh; Schneider, Christina

    2005-01-01

    Developmental (vertical) scales are often constructed for subject areas such as reading and mathematics that are taught continuously in elementary schools. In other subjects such as science, and across a wider grade span, such scales are hard to justify. For tracking student progress and school accountability (including the No Child Left Behind…

  9. Spirit's View on Sol 142 (Vertical)

    NASA Technical Reports Server (NTRS)

    2004-01-01

    This 360-degree view of the terrain surrounding NASA's Mars Exploration Rover Spirit on the 142nd martian day of the rover's mission inside Gusev Crater, on May 27, 2004, was assembled from images taken by Spirit's navigation camera. The rover's position is Site A55. The view is presented in a vertical projection with geometrical seam correction.

  10. Hypersonic shock tunnel heat transfer tests of the Space Shuttle SILTS pod configuration

    NASA Technical Reports Server (NTRS)

    Wittliff, C. E.

    1983-01-01

    Heat transfer measurements have been made on a 0.0175-scale NASA Space Shuttle orbiter model having a simulated SILTS (Shuttle Infrared Leeside Temperature Sensor) pod on top of the vertical tail. Heat transfer distributions were measured both on the pod and on the vertical tail. The test program covered Mach numbers of 8, 11 and 16 in air, at Reynolds numbers from 100,000 to 18 million, based on model length. The angle of attack ranged from 30 deg to 40 deg at sideslip angles from -2 to +2 deg. Data were obtained with 92 thin film assistance thermometers located on the SILTS pod and on the upper 30 percent of the vertical tail. Heat transfer rates measured on the vertical tail show good agreement with flight data obtained from missions STS-1, -2 and -3. The variation of heat transfer to the pod with Reynolds number, Mach number and angle of attack is discussed.

  11. Project Plan for Vertical Lift Machine

    SciTech Connect

    Ellsworth, G F

    2002-08-05

    This document describes the Project Plan for the development and manufacture of a Vertical Lift Machine. It is assumed by this project plan that the Vertical Lift Machine will be developed, designed, manufactured, and tested by a qualified vendor. LLNL will retain review and approval authority for each step given in this project plan. The Vertical Lift Machine is a single linear axis positioning device capable of lifting objects vertically at controlled rates and positioning them repeatedly at predetermined heights, in relation to other objects suspended from above, for high neutron multiplication experiments. Operation of the machine during the experiments is done remotely. The lift mechanism shall accommodate various platforms (tables) that support the objects to be raised. A frame will support additional subassemblies from above such that the lower subassembly can be raised close to and/or interface with those above. The structure must be stiff and motion of the table linear such that radial alignment is maintained (e.g. concentricity). The safe position for the Vertical Lift Machine is the lift mechanism fully retracted with the subassemblies fully separated. The machine shall reside in this position when not in use. It must return to this safe condition from any position upon failure of power sources, open safety interlocks, or operator initiated SCRAM. The Vertical Lift Machine shall have the capability of return to the safe position with no externally applied power. The Vertical Lift Machine shall have dual operator interfaces, one near the machine and another located in a remote control room. Conventional single key, key-lock switching shall be implemented to lock out the control interface not in use. The interface at the machine will be used for testing and ''dry running'' experimental setup(s) with inert subassemblies (i.e. Setup Mode). The remote interface shall provide full control and data recording capability (i.e. Assembly Mode). The control system

  12. Heat transfer performance of a novel double-layer mini-channel heat sink

    NASA Astrophysics Data System (ADS)

    Tang, Biao; Zhou, Rui; Bai, Pengfei; Fu, Ting; Lu, Longsheng; Zhou, Guofu

    2016-07-01

    High pressure drop and significant non-uniformity in temperature distribution along the streamwise direction are still challenges to the design of mini-channel heat sink. High density mini-channel arrays with high liquid-wall contact area are usually pursued in a conventional single-layer design of heat sink, which also inevitably brings high pressure drop. A novel double-layer structured heat sink is proposed in this paper. Four heat sinks with various designs in mini-channel density and flow direction were fabricated and studied experimentally on the heat transfer performance. The single factor of heat load does not show obvious effect on the overall thermal resistance of the heat sinks. On the other hand, slight decrease in thermal resistance was found with the increase in heat load at high flow rates. Moreover, a computational fluid dynamics modeling work was conducted. The results indicate that the parallel cross-flow field regulated by the double-layer structure enhances the heat exchange in both horizontal and vertical directions and consequently gives an uniform temperature distribution and high heat transfer efficiency.

  13. Regenerative Hydride Heat Pump

    NASA Technical Reports Server (NTRS)

    Jones, Jack A.

    1992-01-01

    Hydride heat pump features regenerative heating and single circulation loop. Counterflow heat exchangers accommodate different temperatures of FeTi and LaNi4.7Al0.3 subloops. Heating scheme increases efficiency.

  14. Latent Heating from TRMM Satellite Measurements

    NASA Technical Reports Server (NTRS)

    Tao, Wei-Kuo; Smith, E. A.; Adler, R.; Haddad, Z.; Hou, A.; Iguchi, T.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.

    2004-01-01

    Rainfall production is the fundamental variable within the Earth's hydrological cycle because it is both the principal forcing term in surface water budgets and its energetics corollary, latent heating, is the principal source of atmospheric diabatic heating. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water. The properties of the vertical distribution of latent heat release modulate large-scale meridional and zonal circulations within the tropics - as well as modifying the energetic efficiencies of midlatitude weather systems. This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission (TRMM) satellite observatory, which was launched in November 1997 as a joint American-Japanese space endeavor. Since then, TRMM measurements have been providing an accurate four-dimensional account of rainfall over the global tropics and sub-tropics, information which can be used to estimate the space-time structure of latent heating across the Earth's low latitudes. The paper examines how the observed TRMM distribution of rainfall has advanced an understanding of the global water and energy cycle and its consequent relationship to the atmospheric general circulation and climate via latent heat release. A set of algorithm methodologies that are being used to estimate latent heating based on rain rate retrievals from the TRMM observations are described. The characteristics of these algorithms and the latent heating products that can be generated from them are also described, along with validation analyses of the heating products themselves. Finally, the investigation provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, concluding with remarks intended to stimulate further research on latent heating retrieval from satellites.

  15. Mathematical model and computation of heat distribution for LED heat sink

    NASA Astrophysics Data System (ADS)

    Zhu, J. X.; Sun, L. X.

    2016-05-01

    The light-emitting diode (LED) has many advantages over conventional lighting including lower energy consumption, longer lifetime, improved physical robustness, smaller size, and faster switching. It is noted, however, that its efficiency and lifetime will be degraded severely when it is operated at high temperature. Both previous simulations and experimental results have already indicated that the heat transfer in vertical direction of the LED lamp by conduction is the critical component. In this paper, a simplified mathematical model of the heat source and the conduction distribution for the LED heat sink is developed to estimate the heat distribution in the spherical coordinate system, which can be used for the shape optimization design. Furthermore, the model of the heat conduction equation is solved numerically with the explicit finite-difference method (EFDM). Several numerical simulations show that the model performs well when considering the real situation, so our method is feasible and effective.

  16. THE EFFECT OF VERTICAL TEMPERATURE GRADIENT ON THE PROPAGATION OF THREE-DIMENSIONAL WAVES IN A PROTOPLANETARY DISK

    SciTech Connect

    Lee, Wing-Kit; Gu, Pin-Gao

    2015-11-20

    Excitation and propagation of waves in a thermally stratified disk with an arbitrary vertical temperature profile are studied. Previous analytical studies of three-dimensional waves had been focused on either isothermal or polytropic vertical disk structures. However, at the location in a protoplanetary disk where the dominant heating source is stellar irradiation, the temperature gradient may become positive in the vertical direction. We extend the analysis to study the effects of the vertical temperature structure on the waves that are excited at the Lindblad resonances. For a hotter disk atmosphere, the f-mode contributes less to the torque and remains confined near the midplane as it propagates away from the resonances. On the other hand, the excitation of the g-modes is stronger. As they propagate, they channel to the top of disk atmosphere and their group velocities decrease. The differences compared to previous studies may have implications in understanding the wave dynamics in a realistic disk structure.

  17. Heat transfer coefficients of dilute flowing gas-solids suspensions

    NASA Technical Reports Server (NTRS)

    Kane, R. S.; Pfeffer, R.

    1973-01-01

    Heat transfer coefficients of air-glass, argon-glass, and argon-aluminum suspensions were measured in horizontal and vertical tubes. The glass, 21.6 and 36.0 micron diameter particles, was suspended at gas Reynolds numbers between 11,000 and 21,000 and loading ratios between 0 and 2.5. The presence of particles generally reduced the heat transfer coefficient. The circulation of aluminum powder in the 0.870 inch diameter closed loop system produced tenacious deposits on protuberances into the stream. In the vertical test section, the Nusselt number reduction was attributed to viscous sublayer thickening; in the horizontal test section to particle deposition.

  18. Entirely passive heat-pipe apparatus capable of operating against gravity

    DOEpatents

    Koenig, D.R.

    1981-02-11

    The disclosure is directed to an entirely passive heat pipe apparatus capable of operating against gravity for vertical distances in the order of 3 to 7 and more. A return conduit into which an inert gas is introduced is used to lower the specific density of the working fluid so that it may be returned a greater vertical distance from condenser to evaporator.

  19. Climate Implications of the Observed Changes in Ozone Vertical Distribution

    NASA Astrophysics Data System (ADS)

    Rajeevan, M.

    1996-01-01

    Satellite and ozone-sonde observations indicated a decreasing trend in the ozone concentration in the lower stratosphere and an increasing trend in the troposphere, especially the upper troposphere. We have used a one-dimensional radiative - convective model (RCM) to examine the climate implications of these observed changes in vertical distribution of ozone.Instantaneous radiative forcing calculated by the one-dimensional radiative transfer model indicated a net warming of the surface-troposphere system due to stratospheric ozone losses. The increase in tropospheric ozone causes an additional positive forcing. However, the radiative forcing due to increases in trace gases during the same period is larger than the forcing due to ozone changes. There is marked decrease of the instantaneous solar and longwave heating rates in the lower stratosphere due to stratospheric ozone losses. Increases in tropospheric ozone causes additional decrease in longwave heating rate, in the lower stratosphere.Consistent with the changes in the heating rates, the equilibrium temperature profile computed by the radiative-convective model predicted a cooling in the stratosphere of the order of 06°C and a very slight warming in the troposphere. The increase of tropospheric ozone causes an additional cooling in the stratosphere. The temperature decrease caused by ozone decrease in the lower stratosphere is larger than that caused by increase of trace gases concentration during the same period. The stratospheric cooling effect due to trace gases is, however, better presented near 30 km altitude.Note: Erratum to this article printed: does change abstract Volume 16 Issue 8 pp 959

  20. Latent Heating Structures Derived from TRMM

    NASA Technical Reports Server (NTRS)

    Tao, W.-K.; Smith, E. A.; Adler, R.; Hou, A.; Kakar, R.; Krishnamurti, T.; Kummerow, C.; Lang, S.; Olson, W.; Satoh, S.

    2004-01-01

    Rainfall is the fundamental variable within the Earth's hydrological cycle because it is both the main forcing term leading to variations in continental and oceanic surface water budgets. The vertical distribution of latent heat release, which is accompanied with rain, modulates large-scale meridional and zonal circulations within the tropics as well as modifying the energetic efficiency of mid-latitude weather systems. Latent heat release itself is a consequence of phase changes between the vapor, liquid, and frozen states of water.This paper focuses on the retrieval of latent heat release from satellite measurements generated by the Tropical Rainfall Measuring Mission 0. The TRMM observatory, whose development was a joint US-Japan space endeavor, was launched in November 1997. TRMM measurements provide an accurate account of rainfall over the global tropics, information which can be .used to estimate the four-dimensional structure of latent heating across the entire tropical and sub-tropical regions. Various algorithm methodologies for estimating latent heating based on rain rate measurements from TRMM observations are described. The strengths and weaknesses of these algorithms, as well as the latent heating products generated by these algorithms, are also discussed along with validation analyses of the products. The investigation paper provides an overview of how TRMM-derived latent heating information is currently being used in conjunction with global weather and climate models, and concludes with remarks designed to stimulate further research on latent heating retrieval