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Sample records for model high temperature

  1. Temperature Dependent Residual Stress Models for Ultra-High-Temperature Ceramics on High Temperature Oxidation

    Science.gov (United States)

    Wang, Ruzhuan; Li, Weiguo

    2016-11-01

    The strength of SiC-depleted layer of ultra-high-temperature ceramics on high temperature oxidation degrades seriously. The research for residual stresses developed within the SiC-depleted layer is important and necessary. In this work, the residual stress evolutions in the SiC-depleted layer and the unoxidized substrate in various stages of oxidation are studied by using the characterization models. The temperature and oxidation time dependent mechanical/thermal properties of each phase in SiC-depleted layer are considered in the models. The study shows that the SiC-depleted layer would suffer from large tensile stresses due to the great temperature changes and the formation of pores on high temperature oxidation. The stresses may lead to the cracking and even the delamination of the oxidation layer.

  2. Temperature Dependent Residual Stress Models for Ultra-High-Temperature Ceramics on High Temperature Oxidation

    Science.gov (United States)

    Wang, Ruzhuan; Li, Weiguo

    2017-08-01

    The strength of SiC-depleted layer of ultra-high-temperature ceramics on high temperature oxidation degrades seriously. The research for residual stresses developed within the SiC-depleted layer is important and necessary. In this work, the residual stress evolutions in the SiC-depleted layer and the unoxidized substrate in various stages of oxidation are studied by using the characterization models. The temperature and oxidation time dependent mechanical/thermal properties of each phase in SiC-depleted layer are considered in the models. The study shows that the SiC-depleted layer would suffer from large tensile stresses due to the great temperature changes and the formation of pores on high temperature oxidation. The stresses may lead to the cracking and even the delamination of the oxidation layer.

  3. High temperature furnace modeling and performance verifications

    Science.gov (United States)

    Smith, James E., Jr.

    1992-01-01

    Analytical, numerical, and experimental studies were performed on two classes of high temperature materials processing sources for their potential use as directional solidification furnaces. The research concentrated on a commercially available high temperature furnace using a zirconia ceramic tube as the heating element and an Arc Furnace based on a tube welder. The first objective was to assemble the zirconia furnace and construct parts needed to successfully perform experiments. The 2nd objective was to evaluate the zirconia furnace performance as a directional solidification furnace element. The 3rd objective was to establish a data base on materials used in the furnace construction, with particular emphasis on emissivities, transmissivities, and absorptivities as functions of wavelength and temperature. A 1-D and 2-D spectral radiation heat transfer model was developed for comparison with standard modeling techniques, and were used to predict wall and crucible temperatures. The 4th objective addressed the development of a SINDA model for the Arc Furnace and was used to design sample holders and to estimate cooling media temperatures for the steady state operation of the furnace. And, the 5th objective addressed the initial performance evaluation of the Arc Furnace and associated equipment for directional solidification. Results of these objectives are presented.

  4. Analytic Models of High-Temperature Hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Stygar, W.A.; Olson, R.E.; Spielman, R.B.; Leeper, R.J.

    2000-11-29

    A unified set of high-temperature-hohlraum models has been developed. For a simple hohlraum, P{sub s} = [A{sub s}+(1{minus}{alpha}{sub W})A{sub W}+A{sub H}]{sigma}T{sub R}{sup 4} + (4V{sigma}/c)(dT{sub R}{sup r}/dt) where P{sub S} is the total power radiated by the source, A{sub s} is the source area, A{sub W} is the area of the cavity wall excluding the source and holes in the wall, A{sub H} is the area of the holes, {sigma} is the Stefan-Boltzmann constant, T{sub R} is the radiation brightness temperature, V is the hohlraum volume, and c is the speed of light. The wall albedo {alpha}{sub W} {triple_bond} (T{sub W}/T{sub R}){sup 4} where T{sub W} is the brightness temperature of area A{sub W}. The net power radiated by the source P{sub N} = P{sub S}-A{sub S}{sigma}T{sub R}{sup 4}, which suggests that for laser-driven hohlraums the conversion efficiency {eta}{sub CE} be defined as P{sub N}/P{sub LASER}. The characteristic time required to change T{sub R}{sup 4} in response to a change in P{sub N} is 4V/C[(l{minus}{alpha}{sub W})A{sub W}+A{sub H}]. Using this model, T{sub R}, {alpha}{sub W}, and {eta}{sub CE} can be expressed in terms of quantities directly measurable in a hohlraum experiment. For a steady-state hohlraum that encloses a convex capsule, P{sub N} = {l_brace}(1{minus}{alpha}{sub W})A{sub W}+A{sub H}+[(1{minus}{alpha}{sub C})(A{sub S}+A{sub W}{alpha}{sub W})A{sub C}/A{sub T}]{r_brace}{sigma}T{sub RC}{sup 4} where {alpha}{sub C} is the capsule albedo, A{sub C} is the capsule area, A{sub T} {triple_bond} (A{sub S}+A{sub W}+A{sub H}), and T{sub RC} is the brightness temperature of the radiation that drives the capsule. According to this relation, the capsule-coupling efficiency of the baseline National-Ignition-Facility (NIF) hohlraum is 15% higher than predicted by previous analytic expressions. A model of a hohlraum that encloses a z pinch is also presented.

  5. Dynamic Model of High Temperature PEM Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2007-01-01

    cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes, runs on pure hydrogen in a dead end anode configuration with a purge valve. The cooling of the stack is managed by running...... conduction through stack insulation, cathode air convection and heating of the inlet gasses in manifold. Various measurements are presented to validate the model predictions of the stack temperatures....

  6. Modeling Study of High Pressure and High Temperature Reservoir Fluids

    DEFF Research Database (Denmark)

    Varzandeh, Farhad

    to 250 °C and 2400 bar, in the deep petroleum reservoirs. Furthermore, many of these deep reservoirs are found offshore, including the North Sea and the Gulf of Mexico, making the development even more risky. On the other hand, development of these high pressure high temperature (HPHT) fields can...

  7. HIGH TEMPERATURE HIGH PRESSURE THERMODYNAMIC MEASUREMENTS FOR COAL MODEL COMPOUNDS

    Energy Technology Data Exchange (ETDEWEB)

    Vinayak N. Kabadi

    2000-05-01

    The flow VLE apparatus designed and built for a previous project was upgraded and recalibrated for data measurements for this project. The modifications include better and more accurate sampling technique, addition of a digital recorder to monitor temperature and pressure inside the VLE cell, and a new technique for remote sensing of the liquid level in the cell. VLE data measurements for three binary systems, tetralin-quinoline, benzene--ethylbenzene and ethylbenzene--quinoline, have been completed. The temperature ranges of data measurements were 325 C to 370 C for the first system, 180 C to 300 C for the second system, and 225 C to 380 C for the third system. The smoothed data were found to be fairly well behaved when subjected to thermodynamic consistency tests. SETARAM C-80 calorimeter was used for incremental enthalpy and heat capacity measurements for benzene--ethylbenzene binary liquid mixtures. Data were measured from 30 C to 285 C for liquid mixtures covering the entire composition range. An apparatus has been designed for simultaneous measurement of excess volume and incremental enthalpy of liquid mixtures at temperatures from 30 C to 300 C. The apparatus has been tested and is ready for data measurements. A flow apparatus for measurement of heat of mixing of liquid mixtures at high temperatures has also been designed, and is currently being tested and calibrated.

  8. A THERMODYNAMIC CAVITATION MODEL APPLICABLE TO HIGH TEMPERATURE FLOW

    Directory of Open Access Journals (Sweden)

    De-Min Liu

    2011-01-01

    Full Text Available Cavitation is not only related with pressure, but also affected by temperature. Under high temperature, temperature depression of liquids is caused by latent heat of vaporization. The cavitation characteristics under such condition are different from those under room temperature. The paper focuses on thermodynamic cavitation based on the Rayleigh-Plesset equation and modifies the mass transfer equation with fully consideration of the thermodynamic effects and physical properties. To validate the modified model, the external and internal flow fields, such as hydrofoil NACA0015 and nozzle, are calculated, respectively. The hydrofoil NACA0015's cavitation characteristic is calculated by the modified model at different temperatures. The pressure coefficient is found in accordance with the experimental data. The nozzle cavitation under the thermodynamic condition is calculated and compared with the experiment.

  9. Heat Transfer Modeling for Rigid High-Temperature Fibrous Insulation

    Science.gov (United States)

    Daryabeigi, Kamran; Cunnington, George R.; Knutson, Jeffrey R.

    2012-01-01

    Combined radiation and conduction heat transfer through a high-temperature, high-porosity, rigid multiple-fiber fibrous insulation was modeled using a thermal model previously used to model heat transfer in flexible single-fiber fibrous insulation. The rigid insulation studied was alumina enhanced thermal barrier (AETB) at densities between 130 and 260 kilograms per cubic meter. The model consists of using the diffusion approximation for radiation heat transfer, a semi-empirical solid conduction model, and a standard gas conduction model. The relevant parameters needed for the heat transfer model were estimated from steady-state thermal measurements in nitrogen gas at various temperatures and environmental pressures. The heat transfer modeling methodology was evaluated by comparison with standard thermal conductivity measurements, and steady-state thermal measurements in helium and carbon dioxide gases. The heat transfer model is applicable over the temperature range of 300 to 1360 K, pressure range of 0.133 to 101.3 x 10(exp 3) Pa, and over the insulation density range of 130 to 260 kilograms per cubic meter in various gaseous environments.

  10. Modeling high temperature materials behavior for structural analysis

    CERN Document Server

    Naumenko, Konstantin

    2016-01-01

    This monograph presents approaches to characterize inelastic behavior of materials and structures at high temperature. Starting from experimental observations, it discusses basic features of inelastic phenomena including creep, plasticity, relaxation, low cycle and thermal fatigue. The authors formulate constitutive equations to describe the inelastic response for the given states of stress and microstructure. They introduce evolution equations to capture hardening, recovery, softening, ageing and damage processes. Principles of continuum mechanics and thermodynamics are presented to provide a framework for the modeling materials behavior with the aim of structural analysis of high-temperature engineering components.

  11. A High Temperature Liquid Plasma Model of the Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2007-01-01

    Full Text Available In this work, a liquid model of the Sun is presented wherein the entire solar mass is viewed as a high density/high energy plasma. This model challenges our current understanding of the densities associated with the internal layers of the Sun, advocating a relatively constant density, almost independent of radial position. The incompressible nature of liquids is advanced to prevent solar collapse from gravitational forces. The liquid plasma model of the Sun is a non-equilibrium approach, where nuclear reactions occur throughout the solar mass. The primary means of addressing internal heat transfer are convection and conduction. As a result of the convective processes on the solar surface, the liquid model brings into question the established temperature of the solar photosphere by highlighting a violation of Kirchhoff’s law of thermal emission. Along these lines, the model also emphasizes that radiative emission is a surface phenomenon. Evidence that the Sun is a high density/high energy plasma is based on our knowledge of Planckian thermal emission and condensed matter, including the existence of pressure ionization and liquid metallic hydrogen at high temperatures and pressures. Prior to introducing the liquid plasma model, the historic and scientific justifications for the gaseous model of the Sun are reviewed and the gaseous equations of state are also discussed.

  12. A model of evaluating the pseudogap temperature for high-temperature superconductors

    Indian Academy of Sciences (India)

    Islam M R; Maruf H M A R; Chowdhury F-U-Z

    2016-04-01

    We have presented a model of evaluating the pseudogap temperature for high temperature superconductors using paraconductivity approach. The theoretical analysis is based on the crossing point technique of the conductivity expressions. The pseudogap temperature T $^∗$ is found to depend on dimension and is calculated for 2D and 3D superconducting samples. Numerical calculation is given in favour of the YBCO and doped SmFeAsO$_{1−x}$ samples.

  13. High Temperature Chemical Kinetic Combustion Modeling of Lightly Methylated Alkanes

    Energy Technology Data Exchange (ETDEWEB)

    Sarathy, S M; Westbrook, C K; Pitz, W J; Mehl, M

    2011-03-01

    Conventional petroleum jet and diesel fuels, as well as alternative Fischer-Tropsch (FT) fuels and hydrotreated renewable jet (HRJ) fuels, contain high molecular weight lightly branched alkanes (i.e., methylalkanes) and straight chain alkanes (n-alkanes). Improving the combustion of these fuels in practical applications requires a fundamental understanding of large hydrocarbon combustion chemistry. This research project presents a detailed high temperature chemical kinetic mechanism for n-octane and three lightly branched isomers octane (i.e., 2-methylheptane, 3-methylheptane, and 2,5-dimethylhexane). The model is validated against experimental data from a variety of fundamental combustion devices. This new model is used to show how the location and number of methyl branches affects fuel reactivity including laminar flame speed and species formation.

  14. MELCOR Model Development of High Temperature Gas-cooled Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Jin, Changyong; Huh, Changwook [Korea Institute of Nuclear Safety, Daejeon (Korea, Republic of)

    2013-05-15

    The High Temperature Gas-cooled Reactor is one of the major challenging issues on the development of licensing technology for HTGR. The safety evaluation tools of HTGR can be developed in two ways - development of new HTGR-specific codes or revision of existing codes. The KINS is considering using existing analytic tools to the extent feasible, with appropriate modifications for the intended purpose. The system-level MELCOR code is traditionally used for LWR safety analysis, which is capable of performing thermal-fluid and accident analysis, including fission-product transport and release. Recently, this code is being modified for the NGNP HTGR by the NRC. In this study, the MELCOR input model for HTGR with Reactor Cavity Cooling System (RCCS) was developed and the steady state performance was analyzed to evaluate the applicability in HTGR. HTGR model with design characteristics of GT-MHR was developed using MELCOR 2.1 code to validate the applicability of MELCOR code to HTGR. In addition, the steady state of GT-MHR was analyzed with the developed model. It was evaluated to predict well the design parameters of GT-MHR. The developed model can be used as the basis for accident analysis of HTGR with further update of packages such as Radio Nuclide (RN) package.

  15. Deterministic Modeling of the High Temperature Test Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Ortensi, J.; Cogliati, J. J.; Pope, M. A.; Ferrer, R. M.; Ougouag, A. M.

    2010-06-01

    Idaho National Laboratory (INL) is tasked with the development of reactor physics analysis capability of the Next Generation Nuclear Power (NGNP) project. In order to examine INL’s current prismatic reactor deterministic analysis tools, the project is conducting a benchmark exercise based on modeling the High Temperature Test Reactor (HTTR). This exercise entails the development of a model for the initial criticality, a 19 column thin annular core, and the fully loaded core critical condition with 30 columns. Special emphasis is devoted to the annular core modeling, which shares more characteristics with the NGNP base design. The DRAGON code is used in this study because it offers significant ease and versatility in modeling prismatic designs. Despite some geometric limitations, the code performs quite well compared to other lattice physics codes. DRAGON can generate transport solutions via collision probability (CP), method of characteristics (MOC), and discrete ordinates (Sn). A fine group cross section library based on the SHEM 281 energy structure is used in the DRAGON calculations. HEXPEDITE is the hexagonal z full core solver used in this study and is based on the Green’s Function solution of the transverse integrated equations. In addition, two Monte Carlo (MC) based codes, MCNP5 and PSG2/SERPENT, provide benchmarking capability for the DRAGON and the nodal diffusion solver codes. The results from this study show a consistent bias of 2–3% for the core multiplication factor. This systematic error has also been observed in other HTTR benchmark efforts and is well documented in the literature. The ENDF/B VII graphite and U235 cross sections appear to be the main source of the error. The isothermal temperature coefficients calculated with the fully loaded core configuration agree well with other benchmark participants but are 40% higher than the experimental values. This discrepancy with the measurement stems from the fact that during the experiments the

  16. Modeling for thermal contact resistance of frictional interface under high temperature and high pressure

    Institute of Scientific and Technical Information of China (English)

    湛利华; 李晓谦; 胡仕成; 曹俊

    2002-01-01

    According to the thermodynamic characteristics in the work interface of the plastic forming of metals, a set of TCR (thermal contact resistance) experimental system under the conditions of high temperature and high pressure has been designed. The interrelations between the thermal contact resistance (TCR) and its influence factors such as contact pressure etc, are obtained. A modified coefficient E is introduced to consider the relative slide in the contact interface. Then the interfacial TCR calculating model, which suits to the special conditions of ‘high temperature+plastic rheology' and frictional contact such as continuous roll casting process, is established.

  17. Asymptotic freedom in a string model of high temperature QCD

    CERN Document Server

    Awada, M

    1995-01-01

    Recently we have shown that a phase transition occurs in the leading and subleading approximation of the large N limit in rigid strings coupled to long range Kalb-Ramond interactions. The disordered phase is essentially the Nambu-Goto-Polyakov string theory while the ordered phase is a new theory. In this letter we compute the free energy per unit length of the interacting rigid string at finite temperature. We show that the mass of the winding states solves that of QCD strings in the limit of high temperature. We obtain a precise identification of the QCD coupling constant and those of the interacting rigid string. The relation we obtain is Ng_{QCD}^2 = ({8\\pi^2 (D-2)\\over 9})^2{1\\over 3\\kappa} where \\kappa = {D t \\alpha\\over \\pi \\mu_{c}} is the ratio of the extrinsic curvature coupling constant t, the Kalb-Ramond coupling constant \\alpha, and the critical string tension \\mu_{c}. The running beta function of \\kappa reproduces correctly the asymptotic behaviour of QCD.

  18. Structural analysis of liquid aluminum at high pressure and high temperature using the hard sphere model

    Science.gov (United States)

    Ikuta, Daijo; Kono, Yoshio; Shen, Guoyin

    2016-10-01

    The structure of liquid aluminum is measured up to 6.9 GPa and 1773 K using a multi-angle energy-dispersive X-ray diffraction method in a Paris-Edinburgh press. The effect of pressure and temperature on the structure and density of liquid aluminum is analyzed by means of the hard sphere model. Peak positions in the structure factor of liquid aluminum show a nearly constant value with varying temperatures at ˜1-2 GPa and slightly change with varying pressures up to 6.9 GPa at 1173-1773 K. In contrast, the height of the first peak in the structure factor significantly changes with varying pressures and temperatures. Hard sphere model analysis shows that the structure of liquid aluminum in the pressure-temperature range of this study is controlled mostly by the packing fraction with only a minor change in hard sphere diameters. The obtained packing fractions and hard sphere diameters are used to calculate densities of liquid aluminum at high pressure-temperature conditions.

  19. Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes

    Directory of Open Access Journals (Sweden)

    H. Portner

    2009-08-01

    Full Text Available Models of carbon cycling in terrestrial ecosystems contain formulations for the dependence of respiration on temperature, but the sensitivity of predicted carbon pools and fluxes to these formulations and their parameterization is not understood. Thus, we made an uncertainty analysis of soil organic matter decomposition with respect to its temperature dependency using the ecosystem model LPJ-GUESS.

    We used five temperature response functions (Exponential, Arrhenius, Lloyd-Taylor, Gaussian, Van't Hoff. We determined the parameter uncertainty ranges of the functions by nonlinear regression analysis based on eight experimental datasets from northern hemisphere ecosystems. We sampled over the uncertainty bounds of the parameters and run simulations for each pair of temperature response function and calibration site. The uncertainty in both long-term and short-term soil carbon dynamics was analyzed over an elevation gradient in southern Switzerland.

    The function of Lloyd-Taylor turned out to be adequate for modelling the temperature dependency of soil organic matter decomposition, whereas the other functions either resulted in poor fits (Exponential, Arrhenius or were not applicable for all datasets (Gaussian, Van't Hoff. There were two main sources of uncertainty for model simulations: (1 the uncertainty in the parameter estimates of the response functions, which increased with increasing temperature and (2 the uncertainty in the simulated size of carbon pools, which increased with elevation, as slower turn-over times lead to higher carbon stocks and higher associated uncertainties. The higher uncertainty in carbon pools with slow turn-over rates has important implications for the uncertainty in the projection of the change of soil carbon stocks driven by climate change, which turned out to be more uncertain for higher elevations and hence higher latitudes, which are of key importance for the global terrestrial carbon

  20. Modeling of high temperature- and diffusion-controlled die soldering in aluminum high pressure die casting

    DEFF Research Database (Denmark)

    Domkin, Konstantin; Hattel, Jesper Henri; Thorborg, Jesper

    2009-01-01

    Soldering of cast alloys to the dies has been a continuing source of die surface damage in the aluminum die-casting industry. To reduce the repair and maintenance costs, an approach to modeling the damage and predicting the die lifetime is required. The aim of the present study is the estimation...... of the die lifetime based on a quantitative analysis of die soldering in the framework of the numerical simulations of the die-casting process. Full 3D simulations of the process, including the filling. solidification, and the die cooling, are carried out using the casting simulation software MAGMAsoft....... The resulting transient temperature fields on the die surface and in the casting are then post-processed to estimate the die soldering. The present work deals only with the metallurgical/chemical kind of soldering which occurs at high temperatures and involves formation and growth of intermetallic layers...

  1. Modelling deuterium release from tungsten after high flux high temperature deuterium plasma exposure

    Science.gov (United States)

    Grigorev, Petr; Matveev, Dmitry; Bakaeva, Anastasiia; Terentyev, Dmitry; Zhurkin, Evgeny E.; Van Oost, Guido; Noterdaeme, Jean-Marie

    2016-12-01

    Tungsten is a primary candidate for plasma facing materials for future fusion devices. An important safety concern in the design of plasma facing components is the retention of hydrogen isotopes. Available experimental data is vast and scattered, and a consistent physical model of retention of hydrogen isotopes in tungsten is still missing. In this work we propose a model of non-equilibrium hydrogen isotopes trapping under fusion relevant plasma exposure conditions. The model is coupled to a diffusion-trapping simulation tool and is used to interpret recent experiments involving high plasma flux exposures. From the computational analysis performed, it is concluded that high flux high temperature exposures (T = 1000 K, flux = 1024 D/m2/s and fluence of 1026 D/m2) result in generation of sub-surface damage and bulk diffusion, so that the retention is driven by both sub-surface plasma-induced defects (bubbles) and trapping at natural defects. On the basis of the non-equilibrium trapping model we have estimated the amount of H stored in the sub-surface region to be ∼10-5 at-1, while the bulk retention is about 4 × 10-7 at-1, calculated by assuming the sub-surface layer thickness of about 10 μm and adjusting the trap concentration to comply with the experimental results for the integral retention.

  2. Dynamic Model of the High Temperature Proton Exchange Membrane Fuel Cell Stack Temperature

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2009-01-01

    consists of a prototype cathode air cooled 30 cell HTPEM fuel cell stack developed at the Institute of Energy Technology at Aalborg University. This fuel cell stack uses PEMEAS Celtec P-1000 membranes and runs on pure hydrogen in a dead-end anode configuration with a purge valve. The cooling of the stack...... elements for start-up, heat conduction through stack insulation, cathode air convection, and heating of the inlet gases in the manifold. Various measurements are presented to validate the model predictions of the stack temperatures....

  3. Temperature-variable high-frequency dynamic modeling of PIN diode

    Science.gov (United States)

    Shangbin, Ye; Jiajia, Zhang; Yicheng, Zhang; Yongtao, Yao

    2016-04-01

    The PIN diode model for high frequency dynamic transient characteristic simulation is important in conducted EMI analysis. The model should take junction temperature into consideration since equipment usually works at a wide range of temperature. In this paper, a temperature-variable high frequency dynamic model for the PIN diode is built, which is based on the Laplace-transform analytical model at constant temperature. The relationship between model parameters and temperature is expressed as temperature functions by analyzing the physical principle of these parameters. A fast recovery power diode MUR1560 is chosen as the test sample and its dynamic performance is tested under inductive load by a temperature chamber experiment, which is used for model parameter extraction and model verification. Results show that the model proposed in this paper is accurate for reverse recovery simulation with relatively small errors at the temperature range from 25 to 120 °C. Project supported by the National High Technology and Development Program of China (No. 2011AA11A265).

  4. High Temperature Test Facility Preliminary RELAP5-3D Input Model Description

    Energy Technology Data Exchange (ETDEWEB)

    Bayless, Paul David [Idaho National Laboratory

    2015-12-01

    A RELAP5-3D input model is being developed for the High Temperature Test Facility at Oregon State University. The current model is described in detail. Further refinements will be made to the model as final as-built drawings are released and when system characterization data are available for benchmarking the input model.

  5. High Temperature Flow Response Modeling of Ultra-Fine Grained Titanium

    Directory of Open Access Journals (Sweden)

    Seyed Vahid Sajadifar

    2015-07-01

    Full Text Available This work presents the mechanical behavior modeling of commercial purity titanium subjected to severe plastic deformation (SPD during post-SPD compression, at temperatures of 600-900 °C and at strain rates of 0.001-0.1 s−1. The flow response of the ultra-fine grained microstructure is modeled using the modified Johnson-Cook model as a predictive tool, aiding high temperature forming applications. It was seen that the model was satisfactory at all deformation conditions except for the deformation temperature of 600 °C. In order to improve the predictive capability, the model was extended with a corrective term for predictions at temperatures below 700 °C. The accuracy of the model was displayed with reasonable agreement, resulting in error levels of less than 5% at all deformation temperatures.

  6. Numerical modeling of inward and outward melting of high temperature PCM in a vertical cylinder

    Science.gov (United States)

    Riahi, S.; Saman, W. Y.; Bruno, F.; Tay, N. H. S.

    2016-05-01

    Numerical study of inward and outward melting of a high temperature PCM in cylindrical enclosures were performed, using FLUENT 15. For validation purposes, numerical modeling of inward melting of a low temperature PCM was initially conducted and the predicted results were compared with the experimental data from the literature. The validated model for the low temperature PCM was used for two high temperature cases; inward melting of a high temperature PCM in a cylindrical enclosure and outward melting in a cylindrical case with higher aspect ratio. The results of this study show that the numerical model developed is capable of capturing the details of melting process with buoyancy driven convection for RaPCM and can be used for the design and optimization of a latent heat thermal storage unit.

  7. Modeling of high homologous temperature deformation behavior for stress and life-time analyses

    Energy Technology Data Exchange (ETDEWEB)

    Krempl, E. [Rensselaer Polytechnic Institute, Troy, NY (United States)

    1997-12-31

    Stress and lifetime analyses need realistic and accurate constitutive models for the inelastic deformation behavior of engineering alloys at low and high temperatures. Conventional creep and plasticity models have fundamental difficulties in reproducing high homologous temperature behavior. To improve the modeling capabilities {open_quotes}unified{close_quotes} state variable theories were conceived. They consider all inelastic deformation rate-dependent and do not have separate repositories for creep and plasticity. The viscoplasticity theory based on overstress (VBO), one of the unified theories, is introduced and its properties are delineated. At high homologous temperature where secondary and tertiary creep are observed modeling is primarily accomplished by a static recovery term and a softening isotropic stress. At low temperatures creep is merely a manifestation of rate dependence. The primary creep modeled at low homologous temperature is due to the rate dependence of the flow law. The model is unaltered in the transition from low to high temperature except that the softening of the isotropic stress and the influence of the static recovery term increase with an increase of the temperature.

  8. Thermal modelling of the high temperature treatment of wood based on Luikov's approach

    Energy Technology Data Exchange (ETDEWEB)

    Younsi, R.; Kocaefe, D.; Poncsak, S.; Kocaefe, Y. [University of Quebec, Chicoutimi (Canada). Dept. of Applied Sciences

    2005-07-01

    A 3D, unsteady-state mathematical model was used to simulate the behaviour of wood during high temperature treatment. The model is based on Luikov's approach and solves a set of coupled heat and mass transfer equations. Using the model, the temperature and moisture content profiles of wood were predicted as a function of time for different heating rates. Parallel to the modelling study, an experimental study was carried out using small birch samples. The samples were subjected to high temperature treatment in a thermogravimetric system under different operating conditions. The experimental results and the model predictions were found to be in good agreement. The results show that the distributions of temperature and moisture content are influenced appreciably by the heating rate and the initial moisture content. (author)

  9. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...

  10. SIMULATED MATHEMATICAL MODEL FOR HIGH PRESSURE CYLINDER WALL TEMPERATURE OF HOMEMADE TURBINE

    Institute of Scientific and Technical Information of China (English)

    Shi Xiaoping; Zhu Yin

    2005-01-01

    In order to balance the contradiction between the demand of high precision and that of short time interval of model computing for the power plant simulator, a set of simulated mathematical models are constructed. The model describes the cylinder wall temperature located at four key positions of the high pressure cylinder. The simulated model is confirmed to be not only simple but also precise via comparison between the simulated results and the autoptic data of a power plant.

  11. A granular-biomass high temperature pyrolysis model based on the Darcy flow

    Science.gov (United States)

    Guan, Jian; Qi, Guoli; Dong, Peng

    2015-03-01

    We established a model for the chemical reaction kinetics of biomass pyrolysis via the high-temperature thermal cracking of liquid products. We divided the condensable volatiles into two groups, based on the characteristics of the liquid prdoducts., tar and biomass oil. The effects of temperature, residence time, particle size, velocity, pressure, and other parameters on biomass pyrolysis and high-temperature tar cracking were investigated numerically, and the results were compared with experimental data. The simulation results showed a large endothermic pyrolysis reaction effect on temperature and the reaction process. The pyrolysis reaction zone had a constant temperature period in several layers near the center of large biomass particles. A purely physical heating process was observed before and after this period, according to the temperature index curve.

  12. Consistent negative response of US crops to high temperatures in observations and crop models

    Science.gov (United States)

    Schauberger, Bernhard; Archontoulis, Sotirios; Arneth, Almut; Balkovic, Juraj; Ciais, Philippe; Deryng, Delphine; Elliott, Joshua; Folberth, Christian; Khabarov, Nikolay; Müller, Christoph; Pugh, Thomas A. M.; Rolinski, Susanne; Schaphoff, Sibyll; Schmid, Erwin; Wang, Xuhui; Schlenker, Wolfram; Frieler, Katja

    2017-04-01

    High temperatures are detrimental to crop yields and could lead to global warming-driven reductions in agricultural productivity. To assess future threats, the majority of studies used process-based crop models, but their ability to represent effects of high temperature has been questioned. Here we show that an ensemble of nine crop models reproduces the observed average temperature responses of US maize, soybean and wheat yields. Each day above 30°C diminishes maize and soybean yields by up to 6% under rainfed conditions. Declines observed in irrigated areas, or simulated assuming full irrigation, are weak. This supports the hypothesis that water stress induced by high temperatures causes the decline. For wheat a negative response to high temperature is neither observed nor simulated under historical conditions, since critical temperatures are rarely exceeded during the growing season. In the future, yields are modelled to decline for all three crops at temperatures above 30°C. Elevated CO2 can only weakly reduce these yield losses, in contrast to irrigation.

  13. Consistent negative response of US crops to high temperatures in observations and crop models

    Science.gov (United States)

    Schauberger, Bernhard; Archontoulis, Sotirios; Arneth, Almut; Balkovic, Juraj; Ciais, Philippe; Deryng, Delphine; Elliott, Joshua; Folberth, Christian; Khabarov, Nikolay; Müller, Christoph; Pugh, Thomas A. M.; Rolinski, Susanne; Schaphoff, Sibyll; Schmid, Erwin; Wang, Xuhui; Schlenker, Wolfram; Frieler, Katja

    2017-01-01

    High temperatures are detrimental to crop yields and could lead to global warming-driven reductions in agricultural productivity. To assess future threats, the majority of studies used process-based crop models, but their ability to represent effects of high temperature has been questioned. Here we show that an ensemble of nine crop models reproduces the observed average temperature responses of US maize, soybean and wheat yields. Each day >30 °C diminishes maize and soybean yields by up to 6% under rainfed conditions. Declines observed in irrigated areas, or simulated assuming full irrigation, are weak. This supports the hypothesis that water stress induced by high temperatures causes the decline. For wheat a negative response to high temperature is neither observed nor simulated under historical conditions, since critical temperatures are rarely exceeded during the growing season. In the future, yields are modelled to decline for all three crops at temperatures >30 °C. Elevated CO2 can only weakly reduce these yield losses, in contrast to irrigation.

  14. X-ray spectra of high temperature tungsten plasma calculated with collisional radiative model

    Institute of Scientific and Technical Information of China (English)

    Wang Jun; Zhang Hong; Cheng Xin-Lu

    2013-01-01

    Tungsten is regarded as an important candidate of plasma facing material in international thermonuclear experimental reactor (ITER),so the determination and modeling of spectra of tungsten plasma,especially the spectra at high temperature were intensely focused on recently.In this work,using the atomic structure code of Cowan,a collisional radiative model (CRM) based on the spin-orbit-split-arrays is developed.Based on this model,the charge state distribution of tungsten ions is determined and the soft X-ray spectra from high charged ions of tungsten at different temperatures are calculated.The results show that both the average ionization charge and line positions are well agreed with others calculations and measurements with discrepancies of less than 0.63% and 1.26%,respectively.The spectra at higher temperatures are also reported and the relationship between ion abundance and temperature is predicted in this work.

  15. A new and reliable model for predicting methane viscosity at high pressures and high temperatures

    Institute of Scientific and Technical Information of China (English)

    Ehsan Heidaryan; Jamshid Moghadasi; Amir Salarabadi

    2010-01-01

    In recent years,there has been an increase of interest in the flow of gases at relatively high pressures and high temperatures.Hydrodynamic calculation of the energy losses in the flow of gases in conduits,as well as through the porous media constituting natural petroleum reservoirs,requires knowledge of the viscosity of the fluid at the pressure and temperature involved.Although there are numerous publications concerning the viscosity of methane at atmospheric pressure,there appears to be little information available relating to the effect of pressure and temperature upon the viscosity.A survey of the literature reveals that the disagreements between published data on the viscosity of methane are common and that most investigations have been conducted over restricted temperature and pressure ranges.Experimental viscosity data for methane are presented for temperatures from 320 to 400 K and pressures from 3000 to 140000 kPa by using falling body viscometer.A summary is given to evaluate the available data for methane,and a comparison is presented for that data common to the experimental range reported in this paper.A new and reliable correlation for methane gas viscosity is presented.Predicted values are given for temperatures up to 400 K and pressures up to 140000 kPa with Average Absolute Percent Relative Error(EABS)of 0.794.

  16. RELATION BETWEEN PORE MODEL AND CENTER-LINE TEMPERATURE IN HIGH BURN-UP UO2 PELLET

    Directory of Open Access Journals (Sweden)

    Suwardi Suwardi

    2010-06-01

    Full Text Available Relation between pore model and center-line temperature of high burn up UO2 Pellet. Temperature distribution has been evaluated by using different model of pore distribution. Typical data of power distribution and coolant data have been chosen in this study. Different core model and core distribution model have been studied for related temperature, in correlation with high burn up thermal properties. Finite element combined finite different adapted from Saturn-1 has been used for calculating the temperature distribution. The center-line temperature for different pore model and related discussion is presented.   Keywords: pore model, high burn up, UO2 pellet, centerline temperature.

  17. Comparison of different models for the high-temperature heat-treatment of wood

    Energy Technology Data Exchange (ETDEWEB)

    Kocaefe, Duygu; Younsi, Ramdane; Poncsak, Sandor; Kocaefe, Yasar [Research Group on the Thermotransformation of Wood (GRTB), Department of Applied Sciences, University of Quebec at Chicoutimi, 555, boul. de l' Universite, Chicoutimi, Quebec (Canada)

    2007-07-15

    The high temperature thermal treatment of wood is an environment-friendly method for wood preservation. This technique has attracted considerable attention in recent years. The GRTB (groupe de recherche sur la thermotransformation du bois) at the University of Quebec at Chicoutimi, Canada, has been working on this subject for the past number of years. In this article, the work is presented with a focus on the mathematical modelling of the process. Three models (model based on Luikov's approach, diffusion model, and multiphase model) have been developed for the high temperature treatment of wood. The predictions of the models are compared with the experimental data. The diffusion model was found to be the most practical approach when the accuracy of the results and the computation times are both taken into account. (author)

  18. Multifactorial modelling of high-temperature treatment of timber in the saturated water steam medium

    Science.gov (United States)

    Prosvirnikov, D. B.; Safin, R. G.; Ziatdinova, D. F.; Timerbaev, N. F.; Lashkov, V. A.

    2016-04-01

    The paper analyses experimental data obtained in studies of high-temperature treatment of softwood and hardwood in an environment of saturated water steam. Data were processed in the Curve Expert software for the purpose of statistical modelling of processes and phenomena occurring during this process. The multifactorial modelling resulted in the empirical dependences, allowing determining the main parameters of this type of hydrothermal treatment with high accuracy.

  19. Modeling of high-temperature treatment of wood using the reaction engineering approach (REA).

    Science.gov (United States)

    Putranto, Aditya; Chen, Xiao Dong; Xiao, Zongyuan; Webley, Paul A

    2011-05-01

    A simple and accurate model of high-temperature treatment of wood can assist in the process design and the evaluation of performance of equipment. The high-temperature treatment of wood is essentially a drying process under linearly-increased gas temperature up to final temperature of 220-230°C which is a challenging process to model. This study is aimed to assess the applicability and accuracy of the reaction engineering approach (REA) to model the heat treatment of wood. In order to describe the process using the REA, the maximum activation energy (ΔE(v,b)) is evaluated according to the corresponding external conditions during the heat treatment. Results indicate that the REA coupled with the heat balance describes both moisture content and temperature profiles during the heat treatment very well. A good agreement towards the experimental data is indicated. It has also been shown that the current model is highly comparable in accuracy with the complex models.

  20. Computational model for a high temperature electrolyzer coupled to a HTTR for efficient nuclear hydrogen production

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Daniel; Rojas, Leorlen; Rosales, Jesus; Castro, Landy; Gamez, Abel; Brayner, Carlos, E-mail: danielgonro@gmail.com [Universidade Federal de Pernambuco (UFPE), Recife, PE (Brazil); Garcia, Lazaro; Garcia, Carlos; Torre, Raciel de la, E-mail: lgarcia@instec.cu [Instituto Superior de Tecnologias y Ciencias Aplicadas (InSTEC), La Habana (Cuba); Sanchez, Danny [Universidade Estadual de Santa Cruz (UESC), Ilheus, BA (Brazil)

    2015-07-01

    High temperature electrolysis process coupled to a very high temperature reactor (VHTR) is one of the most promising methods for hydrogen production using a nuclear reactor as the primary heat source. However there are not references in the scientific publications of a test facility that allow to evaluate the efficiency of the process and other physical parameters that has to be taken into consideration for its accurate application in the hydrogen economy as a massive production method. For this lack of experimental facilities, mathematical models are one of the most used tools to study this process and theirs flowsheets, in which the electrolyzer is the most important component because of its complexity and importance in the process. A computational fluid dynamic (CFD) model for the evaluation and optimization of the electrolyzer of a high temperature electrolysis hydrogen production process flowsheet was developed using ANSYS FLUENT®. Electrolyzer's operational and design parameters will be optimized in order to obtain the maximum hydrogen production and the higher efficiency in the module. This optimized model of the electrolyzer will be incorporated to a chemical process simulation (CPS) code to study the overall high temperature flowsheet coupled to a high temperature accelerator driven system (ADS) that offers advantages in the transmutation of the spent fuel. (author)

  1. High Temperature Materials Laboratory

    Data.gov (United States)

    Federal Laboratory Consortium — The High Temperature Materials Lab provides the Navy and industry with affordable high temperature materials for advanced propulsion systems. Asset List: Arc Melter...

  2. A Model for Determining Strength for Embedded Elliptical Crack in Ultra-high-temperature Ceramics

    Directory of Open Access Journals (Sweden)

    Ruzhuan Wang

    2015-08-01

    Full Text Available A fracture strength model applied at room temperature for embedded elliptical crack in brittle solid was obtained. With further research on the effects of various physical mechanisms on material strength, a thermo-damage strength model for ultra-high-temperature ceramics was applied to each temperature phase. Fracture strength of TiC and the changing trends with elliptical crack shape variations under different temperatures were studied. The study showed that under low temperature, the strength is sensitive to the crack shape variation; as the temperature increases, the sensitivities become smaller. The size of ellipse’s minor axes has great effect on the material strength when the ratio of ellipse’s minor and major axes is lower than 0.5, even under relatively high temperatures. The effect of the minor axes of added particle on material properties thus should be considered under this condition. As the crack area is set, the fracture strength decreases firstly and then increases with the increase of ratio of ellipse’s minor and major axes, and the turning point is 0.5. It suggests that for the added particles the ratio of ellipse’s minor and major axes should not be 0.5. All conclusions significantly coincided with the results obtained by using the finite element software ABAQUS.

  3. Application of Gamma code coupled with turbomachinery models for high temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Chang Oh

    2008-02-01

    The very high-temperature gas-cooled reactor (VHTR) is envisioned as a single- or dual-purpose reactor for electricity and hydrogen generation. The concept has average coolant temperatures above 9000C and operational fuel temperatures above 12500C. The concept provides the potential for increased energy conversion efficiency and for high-temperature process heat application in addition to power generation. While all the High Temperature Gas Cooled Reactor (HTGR) concepts have sufficiently high temperature to support process heat applications, such as coal gasification, desalination or cogenerative processes, the VHTR’s higher temperatures allow broader applications, including thermochemical hydrogen production. However, the very high temperatures of this reactor concept can be detrimental to safety if a loss-ofcoolant accident (LOCA) occurs. Following the loss of coolant through the break and coolant depressurization, air will enter the core through the break by molecular diffusion and ultimately by natural convection, leading to oxidation of the in-core graphite structure and fuel. The oxidation will accelerate heatup of the reactor core and the release of a toxic gas, CO, and fission products. Thus, without any effective countermeasures, a pipe break may lead to significant fuel damage and fission product release. Prior to the start of this Korean/United States collaboration, no computer codes were available that had been sufficiently developed and validated to reliably simulate a LOCA in the VHTR. Therefore, we have worked for the past three years on developing and validating advanced computational methods for simulating LOCAs in a VHTR. GAMMA code is being developed to implement turbomachinery models in the power conversion unit (PCU) and ultimately models associated with the hydrogen plant. Some preliminary results will be described in this paper.

  4. Modelling the temperature evolution of bone under high intensity focused ultrasound.

    Science.gov (United States)

    ten Eikelder, H M M; Bošnački, D; Elevelt, A; Donato, K; Di Tullio, A; Breuer, B J T; van Wijk, J H; van Dijk, E V M; Modena, D; Yeo, S Y; Grüll, H

    2016-02-21

    Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

  5. Modelling the temperature evolution of bone under high intensity focused ultrasound

    Science.gov (United States)

    ten Eikelder, H. M. M.; Bošnački, D.; Elevelt, A.; Donato, K.; Di Tullio, A.; Breuer, B. J. T.; van Wijk, J. H.; van Dijk, E. V. M.; Modena, D.; Yeo, S. Y.; Grüll, H.

    2016-02-01

    Magnetic resonance-guided high intensity focused ultrasound (MR-HIFU) has been clinically shown to be effective for palliative pain management in patients suffering from skeletal metastasis. The underlying mechanism is supposed to be periosteal denervation caused by ablative temperatures reached through ultrasound heating of the cortex. The challenge is exact temperature control during sonication as MR-based thermometry approaches for bone tissue are currently not available. Thus, in contrast to the MR-HIFU ablation of soft tissue, a thermometry feedback to the HIFU is lacking, and the treatment of bone metastasis is entirely based on temperature information acquired in the soft tissue adjacent to the bone surface. However, heating of the adjacent tissue depends on the exact sonication protocol and requires extensive modelling to estimate the actual temperature of the cortex. Here we develop a computational model to calculate the spatial temperature evolution in bone and the adjacent tissue during sonication. First, a ray-tracing technique is used to compute the heat production in each spatial point serving as a source term for the second part, where the actual temperature is calculated as a function of space and time by solving the Pennes bio-heat equation. Importantly, our model includes shear waves that arise at the bone interface as well as all geometrical considerations of transducer and bone geometry. The model was compared with a theoretical approach based on the far field approximation and an MR-HIFU experiment using a bone phantom. Furthermore, we investigated the contribution of shear waves to the heat production and resulting temperatures in bone. The temperature evolution predicted by our model was in accordance with the far field approximation and agreed well with the experimental data obtained in phantoms. Our model allows the simulation of the HIFU treatments of bone metastasis in patients and can be extended to a planning tool prior to MR

  6. Comparison of kinetic models for atom recombination on high-temperature reusable surface insulation

    Science.gov (United States)

    Willey, Ronald J.

    1993-01-01

    Five kinetic models are compared for their ability to predict recombination coefficients for oxygen and nitrogen atoms over high-temperature reusable surface insulation (HRSI). Four of the models are derived using Rideal-Eley or Langmuir-Hinshelwood catalytic mechanisms to describe the reaction sequence. The fifth model is an empirical expression that offers certain features unattainable through mechanistic description. The results showed that a four-parameter model, with temperature as the only variable, works best with data currently available. The model describes recombination coefficients for oxygen and nitrogen atoms for temperatures from 300 to 1800 K. Kinetic models, with atom concentrations, demonstrate the influence of atom concentration on recombination coefficients. These models can be used for the prediction of heating rates due to catalytic recombination during re-entry or aerobraking maneuvers. The work further demonstrates a requirement for more recombination experiments in the temperature ranges of 300-1000 K, and 1500-1850 K, with deliberate concentration variation to verify model requirements.

  7. Detection and Analysis of High Temperature Sensitivity of TGMS Lines in Rice Using AMMI Model

    Institute of Scientific and Technical Information of China (English)

    FU Li-zhong; XUE Qing-zhong

    2004-01-01

    With the AMMI(additive main effects and multiplicative interaction)analysis model,the determination of the sensitivity to temperature among different TGMS(thermo-sensitive genic male sterile)lines was performed. To assess the genetic differences due to high temperature stress at. the fertility-sensitive stage(10- 20 d before heading),seven genotypes(six TGMS lines and the control Pei-Ai64S)were grown from May 4 at seven different stages with 10d intervals. The temperatures at. the fertility-sensitive stages involved twelve levels from < 20 to >30℃ under the regime natural conditions in Hangzhou,China. There was considerable variation in pollen fertility among genotypes in response to high temperature. Five genotypes identified as TGMS lines as their percentages of fertile pollens were lower than or close to that. of the. control except for the unstable line RTS19(V6). When the temperatures at. the fertility-sensitive stage were at Ⅰ -Ⅳ,Ⅴ-Ⅵ and Ⅶ-Ⅻ,the percentages of fertile pollens varied in the ranges of 46.46- 48.49%,19.62-22.79% and 3.49- 5.87%,respectively. The critical temperatures of sterility and fertility in the five TGMS lines were 25.1 and 23.0℃,respectively. Considering the amounts and directions of main effect and their IPCA(interaction principal components analysis),we can classify the lines and temperature levels into different groups,and describe the characteristics of genotyPe x temperature interaction,offering the information and tools for the development and utility of thermo-sensitive male sterile lines.Several TGMS rice lines with their reproductive sensitivity to high temperature that can be screened using the AMMI model may add valuable germplasm to the breeding program of hybrid rice.

  8. Solubility Measurements and Modeling of Zinc, Lead and Iron Sulfides at High Temperatures and High Pressures

    DEFF Research Database (Denmark)

    Carolina Figueroa Murcia, Diana; Fosbøl, Philip Loldrup; Thomsen, Kaj

    Solubility measurements of sulfides in aqueous solutions are necessary to understand the behaviour of these scaling minerals in geothermal and oil reservoirs. The low solubility levels of Zinc Sulfide (ZnS), Lead Sulfide (PbS) and Iron Sulfide (FeS) make the solubility measurements a challenging...... task. Consequently existing data are rare and scattered. The aim of this work is to develop a reliable experimental procedure and to measure solubility of sulfides at high temperature and pressures. Additionally the experimental data are used for estimation of the solid-liquid equilibrium using...... oxygen atmosphere to avoid the risk of oxidation of sulfide minerals. The solution is kept in an equilibrium cell at constant temperature and pressure with continuous stirring. The concentration of Zn2+, Pb2+, Fe2+ and S2- are measured using Inductively Coupled Plasma Optical Emission spectrometry (ICP...

  9. Isothermal fatigue behavior and damage modeling of a high temperature woven PMC[Polymer Matrix Composite

    Energy Technology Data Exchange (ETDEWEB)

    Gyekenyesi, A.L.

    2000-01-01

    This study focuses on the fully reversed fatigue behavior exhibited by a carbon fiber/polyimide resin woven laminate at room and elevated temperatures. Nondestructive video edge view microscopy and destructive sectioning techniques were used to study the microscopic damage mechanisms that evolved. The elastic stiffness was monitored and recorded throughout the fatigue life of the coupon. In addition, residual compressive strength tests were conducted on fatigue coupons with various degrees of damage as quantified by stiffness reduction. Experimental results indicated that the monotonic tensile properties were only minimally influenced by temperature, while the monotonic compressive and fully reversed fatigue properties displayed greater reductions due to the elevated temperature. The stiffness degradation as a function of cycles, consisted of three stages; a short-lived high degradation period, a constant degradation rate segment covering the majority of the life, and a final stage demonstrating an increasing rate of degradation up to failure. Concerning the residual compressive strength tests at room and elevated temperatures, the elevated temperature coupons appeared much more sensitive to damage. At elevated temperatures, coupons experienced a much larger loss in compressive strength when compared to room temperature coupons with equivalent damage. The fatigue damage accumulation law proposed for the model incorporates a scalar representation for damage, but admits a multiaxial, anisotropic evolutionary law. The model predicts the current damage (as quantified by residual stiffness) and remnant life of a composite that has undergone a known load at temperature. The damage/life model is dependent on the applied multiaxial stress state as well as temperature. Comparisons between the model and data showed good predictive capabilities concerning stiffness degradation and cycles to failure.

  10. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    2008-01-01

    This work presents the development of an equivalent circuit model of a 65 cell high temperature PEM (HTPEM) fuel cell stack using Electrochemical Impedance Spectroscopy (EIS). The HTPEM fuel cell membranes used are PBI-based and uses phosphoric acid as proton conductor. The operating temperature...... of the MEA's is 160-180oC, depending on the purity of the hydrogen used, the load pattern and the desired lifetime. The advantages of the HTPEM fuel cell technology include fast response to load changes and high tolerance to CO (1-3%)...

  11. Hydrogen/Oxygen Reactions at High Pressures and Intermediate Temperatures: Flow Reactor Experiments and Kinetic Modeling

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Glarborg, Peter

    A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, ignition occurs at the temperature of 775–800 K. In general, the present model provides a good agreement with the measurements in the flow reactor and with recent data on laminar burning velocity and ignition delay time.......A series of experimental and numerical investigations into hydrogen oxidation at high pressures and intermediate temperatures has been conducted. The experiments were carried out in a high pressure laminar flow reactor at 50 bar pressure and a temperature range of 600–900 K. The equivalence ratio......, the mechanism is used to simulate published data on ignition delay time and laminar burning velocity of hydrogen. The flow reactor results show that at reducing, stoichiometric, and oxidizing conditions, conversion starts at temperatures of 750–775 K, 800–825 K, and 800–825 K, respectively. In oxygen atmosphere...

  12. Transient modeling of the thermohydraulic behavior of high temperature heat pipes for space reactor applications

    Science.gov (United States)

    Hall, Michael L.; Doster, Joseph M.

    1986-01-01

    Many proposed space reactor designs employ heat pipes as a means of conveying heat. Previous researchers have been concerned with steady state operation, but the transient operation is of interest in space reactor applications due to the necessity of remote startup and shutdown. A model is being developed to study the dynamic behavior of high temperature heat pipes during startup, shutdown and normal operation under space environments. Model development and preliminary results for a hypothetical design of the system are presented.

  13. Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Kær, Søren Knudsen

    In designing and controlling fuel cell sys-tems it is advantageous having models predicting the behavior of the fuel cells in steady-state as well as in dynamic ope-ration. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterizing and developing a model for a ...... for a high temperature PEM (HTPEM) fuel cell stack. A Labview virtual interface has been developed to perform the signal generation and acquisition which is needed to perform EIS....

  14. Holocene temperature evolution in the Northern Hemisphere high latitudes - Model-data comparisons

    Science.gov (United States)

    Zhang, Yurui; Renssen, Hans; Seppä, Heikki; Valdes, Paul J.

    2017-10-01

    Heterogeneous Holocene climate evolutions in the Northern Hemisphere high latitudes are primarily determined by orbital-scale insolation variations and melting ice sheets. Previous inter-model comparisons have revealed that multi-simulation consistencies vary spatially. We, therefore, compared multiple model results with proxy-based reconstructions in Fennoscandia, Greenland, north Canada, Alaska and Siberia. Our model-data comparisons reveal that data and models generally agree in Fennoscandia, Greenland and Canada, with the early-Holocene warming and subsequent gradual decrease to 0 ka BP (hereinafter referred as ka). In Fennoscandia, simulations and pollen data suggest a 2 °C warming by 8 ka, but this is less expressed in chironomid data. In Canada, a strong early-Holocene warming is suggested by both the simulations and pollen results. In Greenland, the magnitude of early-Holocene warming ranges from 6 °C in simulations to 8 °C in δ18O-based temperatures. Simulated and reconstructed temperatures are mismatched in Alaska. Pollen data suggest strong early-Holocene warming, while the simulations indicate constant Holocene cooling, and chironomid data show a stable trend. Meanwhile, a high frequency of Alaskan peatland initiation before 9 ka can reflect a either high temperature, high soil moisture or large seasonality. In high-latitude Siberia, although simulations and proxy data depict high Holocene temperatures, these signals are noisy owing to a large spread in the simulations and between pollen and chironomid results. On the whole, the Holocene climate evolutions in most regions (Fennoscandia, Greenland and Canada) are well established and understood, but important questions regarding the Holocene temperature trend and mechanisms remain for Alaska and Siberia.

  15. High latitude temperature evolution across the Last Interglacial: a model-data comparison

    Science.gov (United States)

    Capron, Emilie; Stone, Emma; Govin, Aline; Loutre, Marie-France; Masson-Delmotte, Valerie; Mulitza, Stefan; Otto-Bliesner, Betty; Sime, Louise; Waelbroeck, Claire; Wolff, Eric W.

    2014-05-01

    The Last Interglacial (LIG, 129-116 thousand of years, ka) represents an interesting test bed for climate model feedbacks for warmer-than-present high latitudes. However, mainly because synchronising different paleoclimatic archives from different parts of the world is not trivial, a global picture of LIG temperature changes is difficult to obtain. In the framework of the UK iGlass consortium and the European Past4Future project, we have selected 49 polar ice core and sub-polar marine sediment records and developed a strategy to synchronise them onto the recent AICC2012 ice core chronology. This new synthesis enables us to describe the spatial and temporal climatic patterns over polar ice sheets (surface air temperature) and around the ice margins (sea surface temperatures) at a pluri-centennial to millennial-scale. Major features highlighted are (i) non synchronous maximum temperature change between the two hemispheres with the Southern Ocean and Antarctica records showing an early warming compared to North Atlantic records and (ii) Southern hemisphere records exhibiting warm conditions for a longer time period compared to records from the Northern Hemisphere and smaller temperature amplitude changes. Our compiled records are compared with recent snapshot and transient model experiments performed with three state of the art General Circulation Models (HADCM3, CCSM3, FAMOUS) and an Earth Model of Intermediary Complexity (LOVECLIM). Such an exercise enables us to investigate the climate feedbacks which causes the most apparent model-data differences.

  16. Experimental characterization and modelling of UO2 behavior at high temperatures and high strain rates

    Science.gov (United States)

    Salvo, Maxime; Sercombe, Jérôme; Ménard, Jean-Claude; Julien, Jérôme; Helfer, Thomas; Désoyer, Thierry

    2015-01-01

    This work presents an experimental characterization of uranium dioxide (UO2) in compression under Reactivity Initiated Accident (RIA) conditions. Pellet samples were tested at four temperatures (1100, 1350, 1550 and 1700 °C) and at a strain rate varying over 4 decades (10-4-10-3-10-2-10-1 /s). The experimental results show that the stress-strain curves cannot be fitted with a unique power law as it is the case at smaller strain rates (10-9-10-5 /s). A strain-hardening also appears in most of the tests. The microstructural observations show a pronounced evolution of the porosity at the pellet center during the tests. A hyperbolic sine model which accounts for volume variations (pore compressibility) was therefore proposed to describe the behavior of UO2 on a large range of temperatures (1100 - 1700 °C) and strain rates (10-9-10-1 /s). The Finite Element simulations of the compression tests lead to results (maximum stress, axial and hoop strain distribution, porosity distribution) in good agreement with the measurements. The model was then assessed on a database of more than two hundred creep tests.

  17. High-temperature series analyses of the classical Heisenberg and XY model

    CERN Document Server

    Adler, J; Janke, W

    1993-01-01

    Although there is now a good measure of agreement between Monte Carlo and high-temperature series expansion estimates for Ising ($n=1$) models, published results for the critical temperature from series expansions up to 12{\\em th} order for the three-dimensional classical Heisenberg ($n=3$) and XY ($n=2$) model do not agree very well with recent high-precision Monte Carlo estimates. In order to clarify this discrepancy we have analyzed extended high-temperature series expansions of the susceptibility, the second correlation moment, and the second field derivative of the susceptibility, which have been derived a few years ago by L\\"uscher and Weisz for general $O(n)$ vector spin models on $D$-dimensional hypercubic lattices up to 14{\\em th} order in $K \\equiv J/k_B T$. By analyzing these series expansions in three dimensions with two different methods that allow for confluent correction terms, we obtain good agreement with the standard field theory exponent estimates and with the critical temperature estimates...

  18. Temperature model for process impact non-uniformity in genipin recovery by high pressure processing.

    Science.gov (United States)

    Ramos-de-la-Peña, Ana Mayela; Montañez, Julio C; Reyes-Vega, María de la Luz; Contreras-Esquivel, Juan Carlos

    2015-11-15

    A model for the process impact temperature non-uniformity during high pressure processing (HPP) of genipap fruit purees was found during genipin recovery. Purees were subjected to HPP (130-530 MPa) under quasi-isobaric non-isothermal conditions (15 min; 0, 4.6 and 9.3mg pectinases/g fruit). Genipin and protein concentration was determined, and pH was measured. Polygalacturonase activity was quantified indirectly by protein content (mg/g fruit). First order kinetics described temperature changes (0-4 min). Polygalacturonase was activated at 130 MPa, inactivated reversibly at 330 MPa and activated again at 530 MPa. Enzyme reaction rate constant (k) was placed in the 0-4 min model and temperature from 2 to 15 min was described. Protein content and pH characterization in terms of decimal reduction time improved highly the 2-15 min model. Since temperature changes were modeled, more insight of its behavior in an HPP reactor was obtained, avoiding uniformity assumptions, making easier the industrial scale HPP implementation.

  19. Failure Mechanical Behavior of Australian Strathbogie Granite at High Temperatures: Insights from Particle Flow Modeling

    Directory of Open Access Journals (Sweden)

    Sheng-Qi Yang

    2017-05-01

    Full Text Available Thermally induced damage has an important influence on rock mechanics and engineering, especially for high-level radioactive waste repositories, geological carbon storage, underground coal gasification, and hydrothermal systems. Additionally, the wide application of geothermal heat requires knowledge of the geothermal conditions of reservoir rocks at elevated temperature. However, few methods to date have been reported for investigating the micro-mechanics of specimens at elevated temperatures. Therefore, this paper uses a cluster model in particle flow code in two dimensions (PFC2D to simulate the uniaxial compressive testing of Australian Strathbogie granite at various elevated temperatures. The peak strength and ultimate failure mode of the granite specimens at different elevated temperatures obtained by the numerical methods are consistent with those obtained by experimentation. Since the tensile force is always concentrated around the boundary of the crystal, cracks easily occur at the intergranular contacts, especially between the b-b and b-k boundaries where less intragranular contact is observed. The intergranular and intragranular cracking of the specimens is almost constant with increasing temperature at low temperature, and then it rapidly and linearly increases. However, the inflection point of intergranular micro-cracking is less than that of intragranular cracking. Intergranular cracking is more easily induced by a high temperature than intragranular cracking. At an elevated temperature, the cumulative micro-crack counts curve propagates in a stable way during the active period, and it has no unstable crack propagation stage. The micro-cracks and parallel bond forces in the specimens with elevated temperature evolution and axial strain have different characteristics than those at lower temperature. More branch fractures and isolated wider micro-cracks are generated with increasing temperature when the temperature is over 400

  20. Modelling and Evaluation of Heating Strategies for High Temperature Polymer Electrolyte Membrane Fuel Cell Stacks

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Kær, Søren Knudsen

    2008-01-01

    Experiments were conducted on two different cathode air cooled high temperature PEM (HTPEM) fuel cell stacks; a 30 cell 400W prototype stack using two bipolar plates per cell, and a 65 cell 1 kW commercial stack using one bipolar plate per cell. The work seeks to examine the use of different...... heating strategies and find a strategy suited for fast startup of the HTPEM fuel cell stacks. Fast start-up of these high temperature systems enables use in a wide range of applications, such as automotive and auxiliary power units, where immediate system response is needed. The development of a dynamic...... model to simulate the temperature development of a fuel cell stack during heating can be used for assistance in system and control design. The heating strategies analyzed and tested reduced the startup time of one of the fuel cell stacks from 1 h to about 6 min....

  1. Modeling Coupled THM Processes and Brine Migration in Salt at High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Blanco-Martin, Laura [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Molins, Sergi [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Trebotich, David [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Birkholzer, Jens [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2015-09-01

    In this report, we present FY2015 progress by Lawrence Berkeley National Laboratory (LBNL) related to modeling of coupled thermal-hydrological-mechanical-chemical (THMC) processes in salt and their effect on brine migration at high temperatures. This is a combined milestone report related to milestone Salt R&D Milestone “Modeling Coupled THM Processes and Brine Migration in Salt at High Temperatures” (M3FT-15LB0818012) and the Salt Field Testing Milestone (M3FT-15LB0819022) to support the overall objectives of the salt field test planning.

  2. Development of a Numerical Model for High-Temperature Shape Memory Alloys

    Science.gov (United States)

    DeCastro, Jonathan A.; Melcher, Kevin J.; Noebe, Ronald D.; Gaydosh, Darrell J.

    2006-01-01

    A thermomechanical hysteresis model for a high-temperature shape memory alloy (HTSMA) actuator material is presented. The model is capable of predicting strain output of a tensile-loaded HTSMA when excited by arbitrary temperature-stress inputs for the purpose of actuator and controls design. Common quasi-static generalized Preisach hysteresis models available in the literature require large sets of experimental data for model identification at a particular operating point, and substantially more data for multiple operating points. The novel algorithm introduced here proposes an alternate approach to Preisach methods that is better suited for research-stage alloys, such as recently-developed HTSMAs, for which a complete database is not yet available. A detailed description of the minor loop hysteresis model is presented in this paper, as well as a methodology for determination of model parameters. The model is then qualitatively evaluated with respect to well-established Preisach properties and against a set of low-temperature cycled loading data using a modified form of the one-dimensional Brinson constitutive equation. The computationally efficient algorithm demonstrates adherence to Preisach properties and excellent agreement to the validation data set.

  3. Comparison of Two Models for Radiative Heat Transfer in High Temperature Thermal Plasmas

    Directory of Open Access Journals (Sweden)

    Matthieu Melot

    2011-01-01

    Full Text Available Numerical simulation of the arc-flow interaction in high-voltage circuit breakers requires a radiation model capable of handling high-temperature participating thermal plasmas. The modeling of the radiative transfer plays a critical role in the overall accuracy of such CFD simulations. As a result of the increase of computational power, CPU intensive methods based on the radiative transfer equation, leading to more accurate results, are now becoming attractive alternatives to current approximate models. In this paper, the predictive capabilities of the finite volume method (RTE-FVM and the P1 model are investigated. A systematic comparison between these two models and analytical solutions are presented for a variety of relevant test cases. Two implementations of each approach are compared, and a critical evaluation is presented.

  4. Analytic modeling of a high temperature thermoelectric module for wireless sensors

    Science.gov (United States)

    Köhler, J. E.; Staaf, L. G. H.; Palmqvist, A. E. C.; Enoksson, P.

    2014-11-01

    A novel high temperature thermoelectric module with thermoelectric materials never before combined in a module is currently researched. The module placement in the cooling channels of a jet engine where the cold side will be cooled by high flow cooling air (550° C) and the hot side will be at the wall (800° C). The aim of the project is to drastically reduce the length of the wires by replacing wired sensors with wireless sensors and power these (3-10mW) with thermoelectric harvesters. To optimize the design for the temperature range and the environment an analytic model was constructed. Using known models for this purpose was not possible for this project, as many of the models have too many assumptions, e.g. that the temperature gradient is relatively low, that thick electrodes with very low resistance can be used, that the heat transfer through the base plates are perfect or that the aim of the design is to maximize the efficiency. The analytical model in this paper is a combination of several known models with the aim to examine what materials to use in this specific environment to achieve the highest possible specific power (mW/g).

  5. High temperature shock tube experiments and kinetic modeling study of diisopropyl ketone ignition and pyrolysis

    KAUST Repository

    Barari, Ghazal

    2017-03-10

    Diisopropyl ketone (DIPK) is a promising biofuel candidate, which is produced using endophytic fungal conversion. In this work, a high temperature detailed combustion kinetic model for DIPK was developed using the reaction class approach. DIPK ignition and pyrolysis experiments were performed using the UCF shock tube. The shock tube oxidation experiments were conducted between 1093K and 1630K for different reactant compositions, equivalence ratios (φ=0.5–2.0), and pressures (1–6atm). In addition, methane concentration time-histories were measured during 2% DIPK pyrolysis in argon using cw laser absorption near 3400nm at temperatures between 1300 and 1400K near 1atm. To the best of our knowledge, current ignition delay times (above 1050K) and methane time histories are the first such experiments performed in DIPK at high temperatures. Present data were used as validation targets for the new kinetic model and simulation results showed fair agreement compared to the experiments. The reaction rates corresponding to the main consumption pathways of DIPK were found to have high sensitivity in controlling the reactivity, so these were adjusted to attain better agreement between the simulation and experimental data. A correlation was developed based on the experimental data to predict the ignition delay times using the temperature, pressure, fuel concentration and oxygen concentration.

  6. High-temperature experimental and thermodynamic modelling research on the pyrometallurgical processing of copper

    Science.gov (United States)

    Hidayat, Taufiq; Shishin, Denis; Decterov, Sergei A.; Hayes, Peter C.; Jak, Evgueni

    2017-01-01

    Uncertainty in the metal price and competition between producers mean that the daily operation of a smelter needs to target high recovery of valuable elements at low operating cost. Options for the improvement of the plant operation can be examined and decision making can be informed based on accurate information from laboratory experimentation coupled with predictions using advanced thermodynamic models. Integrated high-temperature experimental and thermodynamic modelling research on phase equilibria and thermodynamics of copper-containing systems have been undertaken at the Pyrometallurgy Innovation Centre (PYROSEARCH). The experimental phase equilibria studies involve high-temperature equilibration, rapid quenching and direct measurement of phase compositions using electron probe X-ray microanalysis (EPMA). The thermodynamic modelling deals with the development of accurate thermodynamic database built through critical evaluation of experimental data, selection of solution models, and optimization of models parameters. The database covers the Al-Ca-Cu-Fe-Mg-O-S-Si chemical system. The gas, slag, matte, liquid and solid metal phases, spinel solid solution as well as numerous solid oxide and sulphide phases are included. The database works within the FactSage software environment. Examples of phase equilibria data and thermodynamic models of selected systems, as well as possible implementation of the research outcomes to selected copper making processes are presented.

  7. Internal state variable models for micro- structure in high temperature deformation of titanium alloys

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    There exists an interaction between microstructural evolution and deformation behavior in high temperature deformation of titanium alloys. And the microstruc- ture of titanium alloys is very sensitive to the process parameters of plastic de- formation process. In this paper, on the basis of plastic deformation mechanism of metals and alloys, a microstructural model including dislocation density rate equa- tion and grain growth rate equation is established with the dislocation density rate being an internal state variable. Applying the model to the high temperature de- formation process of Ti60 titanium alloy, the average relative errors of grain sizes between the experiments and the predictions are 9.47% for sampled data, and 13.01% for non-sampled data.

  8. Internal state variable models for micro-structure in high temperature deformation of titanium alloys

    Institute of Scientific and Technical Information of China (English)

    LUO Jiao; LI MiaoQuan; LI XiaoLi

    2008-01-01

    There exists an interaction between microstructural evolution and deformation behavior in high temperature deformation of titanium alloys. And the microstruc-ture of titanium alloys is very sensitive to the process parameters of plastic de-formation process. In this paper, on the basis of plastic deformation mechanism of metals and alloys, a microstructural model including dislocation density rate equa-tion and grain growth rate equation is established with the dislocation density rate being an internal state variable. Applying the model to the high temperature de-formation process of Ti60 titanium alloy, the average relative errors of grain sizes between the experiments and the predictions are 9.47% for sampled data, and 13.01% for non-sampled data.

  9. A constitutive model for particulate-reinforced titanium matrix composites subjected to high strain rates and high temperatures

    Directory of Open Access Journals (Sweden)

    Song Wei-Dong

    2013-01-01

    Full Text Available Quasi-static and dynamic tension tests were conducted to study the mechanical properties of particulate-reinforced titanium matrix composites at strain rates ranging from 0.0001/s to 1000/s and at temperatures ranging from 20 °C to 650 °C Based on the experimental results, a constitutive model, which considers the effects of strain rate and temperature on hot deformation behavior, was proposed for particulate-reinforced titanium matrix composites subjected to high strain rates and high temperatures by using Zener-Hollomon equations including Arrhenius terms. All the material constants used in the model were identified by fitting Zener-Hollomon equations against the experimental results. By comparison of theoretical predictions presented by the model with experimental results, a good agreement was achieved, which indicates that this constitutive model can give an accurate and precise estimate for high temperature flow stress for the studied titanium matrix composites and can be used for numerical simulations of hot deformation behavior of the composites.

  10. An Ising-Anderson model of localisation in high-temperature QCD

    CERN Document Server

    Giordano, Matteo; Pittler, Ferenc

    2015-01-01

    We discuss a possible mechanism leading to localisation of the low-lying Dirac eigenmodes in high-temperature lattice QCD, based on the spatial fluctuations of the local Polyakov lines in the partially ordered configurations above $T_c$. This mechanism provides a qualitative explanation of the dependence of localisation on the temperature and on the lattice spacing, and also of the phase diagram of QCD with an imaginary chemical potential. To test the viability of this mechanism we propose a three-dimensional effective, Anderson-like model, mimicking the effect of the Polyakov lines on the quarks. The diagonal, on-site disorder is governed by a three-dimensional Ising-like spin model with continuous spins. Our numerical results show that localised modes are indeed present in the ordered phase of the Ising model, thus supporting the proposed mechanism for localisation in QCD.

  11. Dark radiation and dark matter in supersymmetric axion models with high reheating temperature

    OpenAIRE

    Graf, Peter; Steffen, Frank Daniel

    2013-01-01

    Recent studies of the cosmic microwave background, large scale structure, and big bang nucleosynthesis (BBN) show trends towards extra radiation. Within the framework of supersymmetric hadronic axion models, we explore two high-reheating-temperature scenarios that can explain consistently extra radiation and cold dark matter (CDM), with the latter residing either in gravitinos or in axions. In the gravitino CDM case, axions from decays of thermal saxions provide extra radiation already prior ...

  12. A dynamic model of an innovative high-temperature solar heating and cooling system

    OpenAIRE

    Buonomano Annamaria; Calise Francesco; Vicidomini Maria

    2016-01-01

    In this paper a new simulation model of a novel solar heating and cooling system based on innovative high temperature flat plate evacuated solar thermal collector is presented. The system configuration includes: flat-plate evacuated solar collectors, a double-stage LiBr-H2O absorption chiller, gas-fired auxiliary heater, a closed loop cooling tower, pumps, heat exchangers, storage tanks, valves, mixers and controllers. The novelty of this study lies in the ...

  13. Advanced High-Temperature Reactor Dynamic System Model Development: April 2012 Status

    Energy Technology Data Exchange (ETDEWEB)

    Qualls, A L; Cetiner, M S; Wilson, Jr, T L

    2012-04-30

    The Advanced High-Temperature Reactor (AHTR) is a large-output fluoride-salt-cooled high-temperature reactor (FHR). An early-phase preconceptual design of a 1500 MW(e) power plant was developed in 2011 [Refs. 1 and 2]. An updated version of this plant is shown as Fig. 1. FHRs feature low-pressure liquid fluoride salt cooling, coated-particle fuel, a high-temperature power cycle, and fully passive decay heat rejection. The AHTR is designed to be a “walk away” reactor that requires no action to prevent large off-site releases following even severe reactor accidents. This report describes the development of dynamic system models used to further the AHTR design toward that goal. These models predict system response during warmup, startup, normal operation, and limited off-normal operating conditions. Severe accidents that include a loss-of-fluid inventory are not currently modeled. The scope of the models is limited to the plant power system, including the reactor, the primary and intermediate heat transport systems, the power conversion system, and safety-related or auxiliary heat removal systems. The primary coolant system, the intermediate heat transport system and the reactor building structure surrounding them are shown in Fig. 2. These systems are modeled in the most detail because the passive interaction of the primary system with the surrounding structure and heat removal systems, and ultimately the environment, protects the reactor fuel and the vessel from damage during severe reactor transients. The reactor silo also plays an important role during system warmup. The dynamic system modeling tools predict system performance and response. The goal is to accurately predict temperatures and pressures within the primary, intermediate, and power conversion systems and to study the impacts of design changes on those responses. The models are design tools and are not intended to be used in reactor qualification. The important details to capture in the primary

  14. Transport and optical conductivity in the Hubbard model: A high-temperature expansion perspective

    Science.gov (United States)

    Perepelitsky, Edward; Galatas, Andrew; Mravlje, Jernej; Žitko, Rok; Khatami, Ehsan; Shastry, B. Sriram; Georges, Antoine

    2016-12-01

    We derive analytical expressions for the spectral moments of the dynamical response functions of the Hubbard model using the high-temperature series expansion. We consider generic dimension d as well as the infinite-d limit, arbitrary electron density n , and both finite and infinite repulsion U . We use moment-reconstruction methods to obtain the one-electron spectral function, the self-energy, and the optical conductivity. They are all smooth functions at high temperature and, at large U , they are featureless with characteristic widths of the order of the lattice hopping parameter t . In the infinite-d limit, we compare the series expansion results with accurate numerical renormalization group and interaction expansion quantum Monte Carlo results. We find excellent agreement down to surprisingly low temperatures, throughout most of the bad-metal regime, which applies for T ≳(1 -n )D , the Brinkman-Rice scale. The resistivity increases linearly in T at high temperature without saturation. This results from the 1 /T behavior of the compressibility or kinetic energy, which play the role of the effective carrier number. In contrast, the scattering time (or diffusion constant) saturates at high T . We find that σ (n ,T )≈(1 -n )σ (n =0 ,T ) to a very good approximation for all n , with σ (n =0 ,T )∝t /T at high temperatures. The saturation at small n occurs due to a compensation between the density dependence of the effective number of carriers and that of the scattering time. The T dependence of the resistivity displays a kneelike feature which signals a crossover to the intermediate-temperature regime where the diffusion constant (or scattering time) starts increasing with decreasing T . At high temperatures, the thermopower obeys the Heikes formula, while the Wiedemann-Franz law is violated with the Lorenz number vanishing as 1 /T2 . The relevance of our calculations to experiments probing high-temperature transport in materials with strong electronic

  15. Modeling Coupled THMC Processes and Brine Migration in Salt at High Temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Rutqvist, Jonny; Blanco Martin, Laura; Mukhopadhyay, Sumit; Houseworth, Jim; Birkholzer, Jens

    2014-08-14

    In this report, we present FY2014 progress by Lawrence Berkeley National Laboratory (LBNL) related to modeling of coupled thermal-hydrological-mechanical-chemical (THMC) processes in salt and their effect on brine migration at high temperatures. LBNL’s work on the modeling of coupled THMC processes in salt was initiated in FY2012, focusing on exploring and demonstrating the capabilities of an existing LBNL modeling tool (TOUGH-FLAC) for simulating temperature-driven coupled flow and geomechanical processes in salt. This work includes development related to, and implementation of, essential capabilities, as well as testing the model against relevant information and published experimental data related to the fate and transport of water. we provide more details on the FY2014 work, first presenting updated tools and improvements made to the TOUGH-FLAC simulator, and the use of this updated tool in a new model simulation of long-term THM behavior within a generic repository in a salt formation. This is followed by the description of current benchmarking and validations efforts, including the TSDE experiment. We then present the current status in the development of constitutive relationships and the dual-continuum model for brine migration. We conclude with an outlook for FY2015, which will be much focused on model validation against field experiments and on the use of the model for the design studies related to a proposed heater experiment.

  16. Constitutive modeling of creep behavior in single crystal superalloys: Effects of rafting at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Ya-Nan, E-mail: fanyn12@mails.tsinghua.edu.cn; Shi, Hui-Ji, E-mail: shihj@mail.tsinghua.edu.cn; Qiu, Wen-Hui

    2015-09-17

    Rafting and creep modeling of single crystal superalloys at high temperatures are important for the safety assessment and life prediction in practice. In this research, a new model has been developed to describe the rafting evolution and incorporated into the Cailletaud single crystal plasticity model to simulate the creep behavior. The driving force of rafting is assumed to be the relaxation of the strain energy, and it is calculated with the local stress state, a superposition of the external and misfit stress tensors. In addition, the isotropic coarsening is introduced by the cube root dependence of the microstructure periodicity on creep time based on Ostwal ripening. Then the influence of rafting on creep deformation is taken into account as the Orowan stress in the single crystal plasticity model. The capability of the proposed model is validated with creep experiments of CMSX-4 at 950 °C and 1050 °C. It is able to predict the rafting direction at complex loading conditions and evaluate the channel width during rafting. For [001] tensile creep tests, good agreement has been shown between the model predictions and experimental results at different temperatures and stress levels. The creep acceleration can be captured with this model and is attributed to the microstructure degradation caused by the precipitate coarsening.

  17. The high-temperature expansion of the classical Ising model with Sz2 term

    Directory of Open Access Journals (Sweden)

    M.T. Thomaz

    2012-03-01

    Full Text Available We derive the high-temperature expansion of the Helmholtz free energy up to order β17 of the one-dimensional spin-S Ising model, with single-ion anisotropy term, in the presence of a longitudinal magnetic field. We show that the values of some thermodynamical functions for the ferromagnetic models, in the presence of a weak magnetic field, are not small corrections to their values with h=0. This model with S=3 was applied by Kishine et al. [J.-i. Kishine et al., Phys. Rev. B, 2006, 74, 224419] to analyze experimental data of the single-chain magnet [Mn (saltmen]2 [Ni(pac2 (py2] (PF62 for T<40 K. We show that for T<35 K the thermodynamic functions of the large-spin limit model are poor approximations to their analogous spin-3 functions.

  18. Procyon: Constraining Its Temperature Structure with High-Precision Interferometry and 3-D Model Atmospheres

    Science.gov (United States)

    Aufdenberg, J. P.; Ludwig, H.-G.; Kervella, P.

    2004-12-01

    We have fit synthetic visibilities from 3-D (CO5BOLD + PHOENIX) and 1-D (PHOENIX, ATLAS12) model stellar atmospheres for Procyon (F5 IV) to high-precision interferometric data from the VINCI instrument at the VLT Interferometer (K-band) and from the Mark III interferometer (500 nm, 800 nm). These data provide a test of theoretical wavelength-dependent limb-darkening predictions, and therefore Procyon's atmospheric temperature structure. Earlier work (Allende Prieto et al. 2002 ApJ 567, 544) has shown that the temperature structure from a spatially and temporally averaged 3-D hydrodynamical model produces significantly less limb darkening at 500 nm relative to the temperature structure from a 1-D MARCS model atmosphere which uses a mixing-length approximation for convective flux transport. Our direct fits to the interferometric data confirm this prediction, however we find that not all 1-D models fail to reproduce the observations. The key to matching the interferometric data is a shallower temperature gradient than provided by the standard 1-D mixing-length approximation. We find that in addition to our best fitting 3-D hydrodynamical model, a 1-D ATLAS12 model, with an additional free parameter for ``approximate overshooting'', provides the required temperature gradient. We estimate that an interferometric precision better than 0.1% will be required to distinguish between the 3-D model and the ATLAS12 model. This overshooting approximation has been shown to match Solar limb-darkening observations reasonably well (Castelli et al 1997 A&A 324, 432), however published work since using Strömgren photometry of solar-type stars has cast doubt on the importance of overshooting. We have also compared synthetic spectral energy distributions for Procyon to ultraviolet, optical and near-infrared spectrophotometry and find differences from comparisons to Strömgren photometry alone. This work was performed in part contract with the Jet Propulsion Laboratory (JPL) funded by

  19. Predictive Finite Rate Model for Oxygen-Carbon Interactions at High Temperature

    Science.gov (United States)

    Poovathingal, Savio

    An oxidation model for carbon surfaces is developed to predict ablation rates for carbon heat shields used in hypersonic vehicles. Unlike existing empirical models, the approach used here was to probe gas-surface interactions individually and then based on an understanding of the relevant fundamental processes, build a predictive model that would be accurate over a wide range of pressures and temperatures, and even microstructures. Initially, molecular dynamics was used to understand the oxidation processes on the surface. The molecular dynamics simulations were compared to molecular beam experiments and good qualitative agreement was observed. The simulations reproduced cylindrical pitting observed in the experiments where oxidation was rapid and primarily occurred around a defect. However, the studies were limited to small systems at low temperatures and could simulate time scales only of the order of nanoseconds. Molecular beam experiments at high surface temperature indicated that a majority of surface reaction products were produced through thermal mechanisms. Since the reactions were thermal, they occurred over long time scales which were computationally prohibitive for molecular dynamics to simulate. The experiments provided detailed dynamical data on the scattering of O, O2, CO, and CO2 and it was found that the data from molecular beam experiments could be used directly to build a model. The data was initially used to deduce surface reaction probabilities at 800 K. The reaction probabilities were then incorporated into the direct simulation Monte Carlo (DSMC) method. Simulations were performed where the microstructure was resolved and dissociated oxygen convected and diffused towards it. For a gas-surface temperature of 800 K, it was found that despite CO being the dominant surface reaction product, a gas-phase reaction forms significant CO2 within the microstructure region. It was also found that surface area did not play any role in concentration of

  20. HIGH TEMPERATURE DISPLACEMENT SENSOR

    Institute of Scientific and Technical Information of China (English)

    Xu Longxiang; Zhang Jinyu; Schweitzer Gerhard

    2005-01-01

    A high temperature displacement sensor based on the principle of eddy-current is investigated. A new temperature compensation technique by using eddy-current effect is presented to satisfy the special requirement at high temperature up to 550℃. The experiment shows that the temperature compensation technique leads to good temperature stability for the sensors. The variation of the sensitivity as well as the temperature drift of the sensor with temperature compensation technique is only about 7.4% and 90~350 mV at 550℃ compared with that at room temperature, and that of the sensor without temperature compensation technique is about 31.2% and 2~3 V at 550℃ compared with that at room temperature. A new dynamic calibration method for the eddy-current displacement sensor is presented, which is very easy to be realized especially in high frequency and at high temperatures. The high temperature displacement sensors developed are successfully used at temperature up to 550℃ in a magnetic bearing system for more than 100 h.

  1. Modeling the Non-linear Viscoelastic Response of High Temperature Polyimides

    CERN Document Server

    Karra, Satish

    2010-01-01

    A constitutive model is developed to predict the viscoelastic response of polyimide resins that are used in high temperature applications. This model is based on a thermodynamic framework that uses the notion that the `natural configuration' of a body evolves as the body undergoes a process and the evolution is determined by maximizing the rate of entropy production in general and the rate of dissipation within purely mechanical considerations. We constitutively prescribe forms for the specific Helmholtz potential and the rate of dissipation (which is the product of density, temperature and the rate of entropy production), and the model is derived by maximizing the rate of dissipation with the constraint of incompressibility, and the reduced energy dissipation equation is also regarded as a constraint in that it is required to be met in every process that the body undergoes. The efficacy of the model is ascertained by comparing the predictions of the model with the experimental data for PMR-15 and HFPE-II-52 ...

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

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-02-01

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

  3. Heat Transfer Measurement and Modeling in Rigid High-Temperature Reusable Surface Insulation Tiles

    Science.gov (United States)

    Daryabeigi, Kamran; Knutson, Jeffrey R.; Cunnington, George R.

    2011-01-01

    Heat transfer in rigid reusable surface insulations was investigated. Steady-state thermal conductivity measurements in a vacuum were used to determine the combined contribution of radiation and solid conduction components of heat transfer. Thermal conductivity measurements at higher pressures were then used to estimate the effective insulation characteristic length for gas conduction modeling. The thermal conductivity of the insulation can then be estimated at any temperature and pressure in any gaseous media. The methodology was validated by comparing estimated thermal conductivities with published data on a rigid high-temperature silica reusable surface insulation tile. The methodology was also applied to the alumina enhanced thermal barrier tiles. Thermal contact resistance for thermal conductivity measurements on rigid tiles was also investigated. A technique was developed to effectively eliminate thermal contact resistance on the rigid tile s cold-side surface for the thermal conductivity measurements.

  4. CONJUGATE MODEL FOR HEAT AND MASS TRANSFER OF POROUS WALL IN THE HIGH TEMPERATURE GAS FLOW

    Institute of Scientific and Technical Information of China (English)

    A.F. Polyakov; D.L.Reviznikov; 沈青; 魏叔如

    2001-01-01

    Heat and mass transfer of a porous permeable wall in a high temperature gas dynamical flow is considered. Numerical simulation is conducted on the ground of the conjugate mathematical model which includes filtration and heat transfer equations in a porous body and boundary layer equations on its surface. Such an approach enables one to take into account complex interaction between heat and mass transfer in the gasdynamical flow and in the structure subjected to this flow.The main attention is given to the impact of the intraporous heat transfer intensity on the transpiration cooling efficiency.

  5. Topological Hubbard model and its high-temperature quantum Hall effect.

    Science.gov (United States)

    Neupert, Titus; Santos, Luiz; Ryu, Shinsei; Chamon, Claudio; Mudry, Christopher

    2012-01-27

    The quintessential two-dimensional lattice model that describes the competition between the kinetic energy of electrons and their short-range repulsive interactions is the repulsive Hubbard model. We study a time-reversal symmetric variant of the repulsive Hubbard model defined on a planar lattice: Whereas the interaction is unchanged, any fully occupied band supports a quantized spin Hall effect. We show that at 1/2 filling of this band, the ground state develops spontaneously and simultaneously Ising ferromagnetic long-range order and a quantized charge Hall effect when the interaction is sufficiently strong. We ponder on the possible practical applications, beyond metrology, that the quantized charge Hall effect might have if it could be realized at high temperatures and without external magnetic fields in strongly correlated materials.

  6. High-Temperature Superconductivity

    Science.gov (United States)

    Tanaka, Shoji

    2006-12-01

    A general review on high-temperature superconductivity was made. After prehistoric view and the process of discovery were stated, the special features of high-temperature superconductors were explained from the materials side and the physical properties side. The present status on applications of high-temperature superconductors were explained on superconducting tapes, electric power cables, magnets for maglev trains, electric motors, superconducting quantum interference device (SQUID) and single flux quantum (SFQ) devices and circuits.

  7. Transformation-induced plasticity in high-temperature shape memory alloys: a one-dimensional continuum model

    Science.gov (United States)

    Sakhaei, Amir Hosein; Lim, Kian-Meng

    2016-07-01

    A constitutive model based on isotropic plasticity consideration is presented in this work to model the thermo-mechanical behavior of high-temperature shape memory alloys. In high-temperature shape memory alloys (HTSMAs), both martensitic transformation and rate-dependent plasticity (creep) occur simultaneously at high temperatures. Furthermore, transformation-induced plasticity is another deformation mechanism during martensitic transformation. All these phenomena are considered as dissipative processes to model the mechanical behavior of HTSMAs in this study. The constitutive model was implemented for one-dimensional cases, and the results have been compared with experimental data from thermal cycling test for actuator applications.

  8. Characterisation and modelling of a high temperature PEM fuel cell stack using electrochemical impedance spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Jespersen, J.L. [Danish Technological Institute, Kongsvang Alle 29, DK-8000 Arhus C (Denmark); Schaltz, E.; Kaer, S.K. [Department of Energy Technology, Aalborg University, Pontoppidanstraede 101, DK-9220 Aalborg East (Denmark); Andreasen, S.J.

    2009-08-15

    In designing and controlling fuel cell systems, it is advantageous to have models which predict fuel cell behaviour in steady-state as well as in dynamic operation. This work examines the use of electro-chemical impedance spectroscopy (EIS) for characterising and developing an impedance model for a high temperature PEM (HT-PEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell is a Nyquist plot, which shows the imaginary and real parts of the impedance of the measured system. The full stack impedance depends on the impedance of each of the single cells of the stack. Equivalent circuit models for each single cell can be used to predict the stack impedance at different temperature profiles of the stack. The information available in such models can be used to predict the fuel cell stack performance, e.g. in systems where different electronic components introduce current harmonics. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  9. Experimental characterization and modelling of UO{sub 2} behavior at high temperatures and high strain rates

    Energy Technology Data Exchange (ETDEWEB)

    Salvo, Maxime, E-mail: maxime.salvo@cea.fr [CEA, DEN, DEC/SESC, F-13108 Saint-Paul-lez-Durance (France); Sercombe, Jérôme [CEA, DEN, DEC/SESC, F-13108 Saint-Paul-lez-Durance (France); Ménard, Jean-Claude [CEA, DEN, DEC/SPUA, F-13108 Saint-Paul-lez-Durance (France); Julien, Jérôme; Helfer, Thomas [CEA, DEN, DEC/SESC, F-13108 Saint-Paul-lez-Durance (France); Désoyer, Thierry [CNRS, LMA, 13402 Marseille Cedex 20 (France)

    2015-01-15

    Highlights: • This paper presents an experimental characterization of UO{sub 2} in compression. • The tests are performed at high temperatures (1100–1700 °C) and high strain rates (10{sup -4}–10{sup -1}/s). • With a power law model, the stress exponent n deduced from the tests varies between 16 and 20. • A hyperbolic sine model was therefore developed to describe UO{sub 2} behavior at high strain rates. • Pore compressibility as observed during the tests was introduced in the model. - Abstract: This work presents an experimental characterization of uranium dioxide (UO{sub 2}) in compression under Reactivity Initiated Accident (RIA) conditions. Pellet samples were tested at four temperatures (1100, 1350, 1550 and 1700°C) and at a strain rate varying over 4 decades (10{sup -4}–10{sup -3}–10{sup -2}–10{sup -1}/s). The experimental results show that the stress–strain curves cannot be fitted with a unique power law as it is the case at smaller strain rates (10{sup -9}–10{sup -5}/s). A strain-hardening also appears in most of the tests. The microstructural observations show a pronounced evolution of the porosity at the pellet center during the tests. A hyperbolic sine model which accounts for volume variations (pore compressibility) was therefore proposed to describe the behavior of UO{sub 2} on a large range of temperatures (1100-1700°C) and strain rates (10{sup -9}–10{sup -1}/s). The Finite Element simulations of the compression tests lead to results (maximum stress, axial and hoop strain distribution, porosity distribution) in good agreement with the measurements. The model was then assessed on a database of more than two hundred creep tests.

  10. A High Temperature Polymer Electrolyte Membrane Fuel Cell Model for Reformate Gas

    Directory of Open Access Journals (Sweden)

    M. Mamlouk

    2011-01-01

    Full Text Available A one-dimensional model of a high temperature polymer electrolyte membrane fuel cell using polybenzimidazole (PBI membranes is described. The model considers mass transport through a thin film electrolyte covering the catalyst particles as well as through the porous media. The incorporation of a thin film model describing reactant gas mass transport through electrolyte covering the electrocatalyst is shown to be an essential requirement for accurate simulation. The catalyst interface is represented using a macrohomogeneous model. The influence of carbon monoxide, carbon dioxide, and methane, which would be present in a reformate gas, is considered in terms of the effect on the anode polarisation/kinetics behaviour. The model simulates the influence of operating conditions, cell parameters, and fuel gas compositions on the cell voltage current density characteristics. The model gives good predictions of the effect of oxygen and air pressures on cell behaviour and correctly simulates the mass transport behaviour of the cell. The model with reformate gas shows that additional voltage losses associated with CO poisoning can lead to loss in voltage of tens of mV and thus reduction in power.

  11. Creep-Fatigue Damage Investigation and Modeling of Alloy 617 at High Temperatures

    Science.gov (United States)

    Tahir, Fraaz

    The Very High Temperature Reactor (VHTR) is one of six conceptual designs proposed for Generation IV nuclear reactors. Alloy 617, a solid solution strengthened Ni-base superalloy, is currently the primary candidate material for the tubing of the Intermediate Heat Exchanger (IHX) in the VHTR design. Steady-state operation of the nuclear power plant at elevated temperatures leads to creep deformation, whereas loading transients including startup and shutdown generate fatigue. A detailed understanding of the creep-fatigue interaction in Alloy 617 is necessary before it can be considered as a material for nuclear construction in ASME Boiler and Pressure Vessel Code. Current design codes for components undergoing creep-fatigue interaction at elevated temperatures require creep-fatigue testing data covering the entire range from fatigue-dominant to creep-dominant loading. Classical strain-controlled tests, which produce stress relaxation during the hold period, show a saturation in cycle life with increasing hold periods due to the rapid stress-relaxation of Alloy 617 at high temperatures. Therefore, applying longer hold time in these tests cannot generate creep-dominated failure. In this study, uniaxial isothermal creep-fatigue tests with non-traditional loading waveforms were designed and performed at 850 and 950°C, with an objective of generating test data in the creep-dominant regime. The new loading waveforms are hybrid strain-controlled and force-controlled testing which avoid stress relaxation during the creep hold. The experimental data showed varying proportions of creep and fatigue damage, and provided evidence for the inadequacy of the widely-used time fraction rule for estimating creep damage under creep-fatigue conditions. Micro-scale damage features in failed test specimens, such as fatigue cracks and creep voids, were quantified using a Scanning Electron Microscope (SEM) to find a correlation between creep and fatigue damage. Quantitative statistical

  12. Highly efficient high temperature electrolysis

    DEFF Research Database (Denmark)

    Hauch, Anne; Ebbesen, Sune; Jensen, Søren Højgaard;

    2008-01-01

    High temperature electrolysis of water and steam may provide an efficient, cost effective and environmentally friendly production of H-2 Using electricity produced from sustainable, non-fossil energy sources. To achieve cost competitive electrolysis cells that are both high performing i.e. minimum...... internal resistance of the cell, and long-term stable, it is critical to develop electrode materials that are optimal for steam electrolysis. In this article electrolysis cells for electrolysis of water or steam at temperatures above 200 degrees C for production of H-2 are reviewed. High temperature...... electrolysis is favourable from a thermodynamic point of view, because a part of the required energy can be supplied as thermal heat, and the activation barrier is lowered increasing the H-2 production rate. Only two types of cells operating at high temperature (above 200 degrees C) have been described...

  13. A dynamic model of an innovative high-temperature solar heating and cooling system

    Directory of Open Access Journals (Sweden)

    Buonomano Annamaria

    2016-01-01

    Full Text Available In this paper a new simulation model of a novel solar heating and cooling system based on innovative high temperature flat plate evacuated solar thermal collector is presented. The system configuration includes: flat-plate evacuated solar collectors, a double-stage LiBr-H2O absorption chiller, gas-fired auxiliary heater, a closed loop cooling tower, pumps, heat exchangers, storage tanks, valves, mixers and controllers. The novelty of this study lies in the utilization of flat-plate stationary solar collectors, manufactured by TVP Solar, rather than concentrating ones (typically adopted for driving double-stage absorption chillers. Such devices show ultra-high thermal efficiencies, even at very high (about 200°C operating temperatures, thanks to the high vacuum insulation. Aim of the paper is to analyse the energy and economic feasibility of such novel technology, by including it in a prototypal solar heating and cooling system. For this purpose, the solar heating and cooling system design and performance were analysed by means of a purposely developed dynamic simulation model, implemented in TRNSYS. A suitable case study is also presented. Here, the simulated plant is conceived for the space heating and cooling and the domestic hot water production of a small building, whose energy needs are fulfilled through a real installation (settled also for experimental purposes built up close to Naples (South Italy. Simulation results show that the investigated system is able to reach high thermal efficiencies and very good energy performance. Finally, the economic analysis shows results comparable to those achieved through similar renewable energy systems.

  14. Modelling temperature-dependent heat production over decades in High Arctic coal waste rock piles

    DEFF Research Database (Denmark)

    Hollesen, Jørgen; Elberling, Bo; Jansson, P.E.

    2011-01-01

    controlling the internal build up of heat leading to potential self-incineration. However, site specific measurements of temperature-dependent heat production as well as simulation results show that the heat produced from pyrite oxidation alone cannot cause such a temperature increase and that processes......Subsurface heat production from oxidation of pyrite is an important process that may increase subsurface temperatures within coal waste rock piles and increase the release of acid mine drainage, AMD. Waste rock piles in the Arctic are especially vulnerable to changes in subsurface temperatures...... as the release of AMD normally is limited by permafrost. Here we show that temperatures within a 20 year old heat-producing waste rock pile in Svalbard (78°N) can be modelled by the one-dimensional heat and water flow model (CoupModel) with a new temperature-dependent heat-production module that includes both...

  15. Hydrogen oxidation at high pressure and intermediate temperatures: experiments and kinetic modeling

    DEFF Research Database (Denmark)

    Hashemi, Hamid; Christensen, Jakob Munkholt; Gersen, Sander

    2015-01-01

    Hydrogen oxidation at 50 bar and temperatures of 700–900 K was investigated in a high pressure laminar flow reactor under highly diluted conditions. The experiments provided information about H 2 oxidation at pressures above the third explosion limit. The fuel–air equivalence ratio of the reactants...... was varied from very oxidizing to strongly reducing conditions. The results supplement high-pressure data from RCM (900–1100 K) and shock tubes (900–2200 K). At the reducing conditions ( U = 12), oxidation started at 748–775 K while it was shifted to 798–823 K for stoichiometric and oxidizing conditions ( U...... = 1.03 and 0.05). At very oxidizing conditions (O 2 atmosphere, U = 0.0009), the temperature for onset of reaction was reduced to 775–798 K. The data were interpreted in terms of a detailed chemical kinetic model, drawn mostly from work of Burke and coworkers. In the present study, the rate constants...

  16. THATCH: A computer code for modelling thermal networks of high- temperature gas-cooled nuclear reactors

    Energy Technology Data Exchange (ETDEWEB)

    Kroeger, P.G.; Kennett, R.J.; Colman, J.; Ginsberg, T. (Brookhaven National Lab., Upton, NY (United States))

    1991-10-01

    This report documents the THATCH code, which can be used to model general thermal and flow networks of solids and coolant channels in two-dimensional r-z geometries. The main application of THATCH is to model reactor thermo-hydraulic transients in High-Temperature Gas-Cooled Reactors (HTGRs). The available modules simulate pressurized or depressurized core heatup transients, heat transfer to general exterior sinks or to specific passive Reactor Cavity Cooling Systems, which can be air or water-cooled. Graphite oxidation during air or water ingress can be modelled, including the effects of added combustion products to the gas flow and the additional chemical energy release. A point kinetics model is available for analyzing reactivity excursions; for instance due to water ingress, and also for hypothetical no-scram scenarios. For most HTGR transients, which generally range over hours, a user-selected nodalization of the core in r-z geometry is used. However, a separate model of heat transfer in the symmetry element of each fuel element is also available for very rapid transients. This model can be applied coupled to the traditional coarser r-z nodalization. This report described the mathematical models used in the code and the method of solution. It describes the code and its various sub-elements. Details of the input data and file usage, with file formats, is given for the code, as well as for several preprocessing and postprocessing options. The THATCH model of the currently applicable 350 MW{sub th} reactor is described. Input data for four sample cases are given with output available in fiche form. Installation requirements and code limitations, as well as the most common error indications are listed. 31 refs., 23 figs., 32 tabs.

  17. Thermophysical characterization tools and numerical models for high temperature thermo-structural composite materials; Outils de caracterisation thermophysique et modeles numeriques pour les composites thermostructuraux a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Lorrette, Ch

    2007-04-15

    This work is an original contribution to the study of the thermo-structural composite materials thermal behaviour. It aims to develop a methodology with a new experimental device for thermal characterization adapted to this type of material and to model the heat transfer by conduction within these heterogeneous media. The first part deals with prediction of the thermal effective conductivity of stratified composite materials in the three space directions. For that, a multi scale model using a rigorous morphology analysis of the structure and the elementary properties is proposed and implemented. The second part deals with the thermal characterization at high temperature. It shows how to estimate simultaneously the thermal effusiveness and the thermal conductivity. The present method is based on the observation of the heating from a plane sample submitted to a continuous excitation generated by Joule Effect. Heat transfer is modelled with the quadrupole formalism, temperature is here measured on two sides of the sample. The development of both resistive probes for excitation and linear probes for temperature measurements enables the thermal properties measured up to 1000 C. Finally, some experimental and numerical application examples lead to review the obtained results. (author)

  18. A model for steady state stage III creep regime at low-high stress/temperature range

    Directory of Open Access Journals (Sweden)

    Nicola Bonora

    2008-07-01

    Full Text Available Although diffusional flow creep is often considered out of practical engineering applications, the need for a model capable to account for the resulting action of both diffusional and dislocation type creep is justified by the increasing demands of reliable creep design for very long lives (exceeding 100.000h, high stress-low temperatures and high temperature-low stress regimes. In this paper, a creep model formulation, in which the change of the creep mechanism has been accounted for through an explicit dependence of the creep exponent n on stress and temperature, has been proposed. An application example of the proposed approach to high purity aluminum is given.

  19. High-Temperature Cutoff Approximation of the 3D Kinetic Ising Model

    Institute of Scientific and Technical Information of China (English)

    ZHU JianYang; YANG ZhanRu

    2001-01-01

    A single-spin transition critical dynamics is used to investigate the three-dimensional kinetic Ising model on an anisotropic cubic lattice. We first derive the fundamental dynamical equations, and then linearize them by a cutoff approximation. We obtain the approximate solutions of the local magnetization and equal-time pair correlation function in zero field. In which the axial-decoupling terms γ1γ2, γ2γ3 and γ1γ3 as higher infinitesimal quantity are ignored, where γa = tanh(2kα) = tanh(2Jα/kβT) (α = 1,2,3). We think that it is reasonable as the temperature of the system is very high. The result of what we obtain in this paper can go back to the one-dimensional Glauber's theory as long as k2 = k3= 0.

  20. High Temperature Aquifer Storage

    Science.gov (United States)

    Ueckert, Martina; Niessner, Reinhard; Baumann, Thomas

    2016-04-01

    Combined heat and power generation (CHP) is highly efficient because excess heat is used for heating and/or process energy. However, the demand of heat energy varies considerably throughout the year while the demand for electrical energy is rather constant. It seems economically and ecologically highly beneficial for municipalities and large power consumers such as manufacturing plants to store excess heat in groundwater aquifers and to recuperate this energy at times of higher demand. Within the project High Temperature Aquifer Storage, scientists investigate storage and recuperation of excess heat energy into the bavarian Malm aquifer. Apart from high transmissivity and favorable pressure gradients, the hydrochemical conditions are crucial for long-term operation. An enormous technical challenge is the disruption of the carbonate equilibrium - modeling results indicated a carbonate precipitation of 10 - 50 kg/d in the heat exchangers. The test included five injection pulses of hot water (60 °C up to 110 °C) and four tracer pulses, each consisting of a reactive and a conservative fluorescent dye, into a depth of about 300 m b.s.l. resp. 470 m b.s.l. Injection and production rates were 15 L/s. To achieve the desired water temperatures, about 4 TJ of heat energy were necessary. Electrical conductivity, pH and temperature were recorded at a bypass where also samples were taken. A laboratory container at the drilling site was equipped for analysing the concentration of the dyes and the major cations at sampling intervals of down to 15 minutes. Additional water samples were taken and analysed in the laboratory. The disassembled heat exchanger prooved that precipitation was successfully prevented by adding CO2 to the water before heating. Nevertheless, hydrochemical data proved both, dissolution and precipitation processes in the aquifer. This was also suggested by the hydrochemical modelling with PhreeqC and is traced back to mixture dissolution and changing

  1. High temperature battery. Hochtemperaturbatterie

    Energy Technology Data Exchange (ETDEWEB)

    Bulling, M.

    1992-06-04

    To prevent heat losses of a high temperature battery, it is proposed to make the incoming current leads in the area of their penetration through the double-walled insulating housing as thermal throttle, particularly spiral ones.

  2. High Temperature Capacitor Development

    Energy Technology Data Exchange (ETDEWEB)

    John Kosek

    2009-06-30

    The absence of high-temperature electronics is an obstacle to the development of untapped energy resources (deep oil, gas and geothermal). US natural gas consumption is projected to grow from 22 trillion cubic feet per year (tcf) in 1999 to 34 tcf in 2020. Cumulatively this is 607 tcf of consumption by 2020, while recoverable reserves using current technology are 177 tcf. A significant portion of this shortfall may be met by tapping deep gas reservoirs. Tapping these reservoirs represents a significant technical challenge. At these depths, temperatures and pressures are very high and may require penetrating very hard rock. Logistics of supporting 6.1 km (20,000 ft) drill strings and the drilling processes are complex and expensive. At these depths up to 50% of the total drilling cost may be in the last 10% of the well depth. Thus, as wells go deeper it is increasingly important that drillers are able to monitor conditions down-hole such as temperature, pressure, heading, etc. Commercial off-the-shelf electronics are not specified to meet these operating conditions. This is due to problems associated with all aspects of the electronics including the resistors and capacitors. With respect to capacitors, increasing temperature often significantly changes capacitance because of the strong temperature dependence of the dielectric constant. Higher temperatures also affect the equivalent series resistance (ESR). High-temperature capacitors usually have low capacitance values because of these dielectric effects and because packages are kept small to prevent mechanical breakage caused by thermal stresses. Electrolytic capacitors do not operate at temperatures above 150oC due to dielectric breakdown. The development of high-temperature capacitors to be used in a high-pressure high-temperature (HPHT) drilling environment was investigated. These capacitors were based on a previously developed high-voltage hybridized capacitor developed at Giner, Inc. in conjunction with a

  3. High-temperature superconductors

    CERN Document Server

    Saxena, Ajay Kumar

    2010-01-01

    The present book aims at describing the phenomenon of superconductivity and high-temperature superconductors discovered by Bednorz and Muller in 1986. The book covers the superconductivity phenomenon, structure of high-Tc superconductors, critical currents, synthesis routes for high Tc materials, superconductivity in cuprates, the proximity effect and SQUIDs, theories of superconductivity and applications of superconductors.

  4. High Temperature ESP Monitoring

    Energy Technology Data Exchange (ETDEWEB)

    Jack Booker; Brindesh Dhruva

    2011-06-20

    The objective of the High Temperature ESP Monitoring project was to develop a downhole monitoring system to be used in wells with bottom hole well temperatures up to 300°C for measuring motor temperature, formation pressure, and formation temperature. These measurements are used to monitor the health of the ESP motor, to track the downhole operating conditions, and to optimize the pump operation. A 220 ºC based High Temperature ESP Monitoring system was commercially released for sale with Schlumberger ESP motors April of 2011 and a 250 ºC system with will be commercially released at the end of Q2 2011. The measurement system is now fully qualified, except for the sensor, at 300 °C.

  5. High Temperature Electrolysis

    DEFF Research Database (Denmark)

    Elder, Rachael; Cumming, Denis; Mogensen, Mogens Bjerg

    2015-01-01

    High temperature electrolysis of carbon dioxide, or co-electrolysis of carbon dioxide and steam, has a great potential for carbon dioxide utilisation. A solid oxide electrolysis cell (SOEC), operating between 500 and 900. °C, is used to reduce carbon dioxide to carbon monoxide. If steam is also...... input to the cell then hydrogen is produced giving syngas. This syngas can then be further reacted to form hydrocarbon fuels and chemicals. Operating at high temperature gives much higher efficiencies than can be achieved with low temperature electrolysis. Current state of the art SOECs utilise a dense...

  6. High accuracy computational methods for behavioral modeling of thick-film resistors at cryogenic temperatures

    Directory of Open Access Journals (Sweden)

    Balik Franciszek

    2016-03-01

    Full Text Available The aim of this work was to elaborate two-dimensional behavioral modeling method of thick-film resistors working in low-temperature conditions. The investigated resistors (made from 5 various resistive inks: 10 resistor coupons, each with 36 resistors with various dimensions, were measured automatically in a cryostat system. The low temperature was achieved in a nitrogen-helium continuous-flow cryostat. For nitrogen used as a freezing liquid the minimal temperature possible to achieve was equal to −195.85 °C (77.3 K. Mathematical model in the form of a multiplication of two polynomials was elaborated based on the above mentioned measurements. The first polynomial approximated temperature behavior of the normalized resistance, while the second one described the dependence of resistance on planar resistors dimensions. Special computational procedures for multidimensional approximation purpose were elaborated. It was shown that proper approximation polynomials and sufficiently exact methods of calculations ensure acceptable modeling errors.

  7. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Scott, James; Boudreau, Kate; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom; Zhang, Shujun

    2009-01-01

    The current NASA Decadal mission planning effort has identified Venus as a significant scientific target for a surface in-situ sampling/analyzing mission. The Venus environment represents several extremes including high temperature (460 deg C), high pressure (9 MPa), and potentially corrosive (condensed sulfuric acid droplets that adhere to surfaces during entry) environments. This technology challenge requires new rock sampling tools for these extreme conditions. Piezoelectric materials can potentially operate over a wide temperature range. Single crystals, like LiNbO3, have a Curie temperature that is higher than 1000 deg C and the piezoelectric ceramics Bismuth Titanate higher than 600 deg C. A study of the feasibility of producing piezoelectric drills that can operate in the temperature range up to 500 deg C was conducted. The study includes the high temperature properties investigations of engineering materials and piezoelectric ceramics with different formulas and doping. The drilling performances of a prototype Ultrasonic/Sonic Drill/Corer (USDC) using high temperate piezoelectric ceramics and single crystal were tested at temperature up to 500 deg C. The detailed results of our study and a discussion of the future work on performance improvements are presented in this paper.

  8. A Modified Johnson-Cook Model for Advanced High-Strength Steels Over a Wide Range of Temperatures

    Science.gov (United States)

    Qingdong, Zhang; Qiang, Cao; Xiaofeng, Zhang

    2014-12-01

    Advanced high-strength steel (AHSS) is widely used in automotive industry. In order to investigate the mechanical behaviors of AHSS over a wide range of temperatures, quasi-static tensile experiments were conducted at the temperatures from 298 to 1073 K on a Gleeble-3500 thermo-simulation machine. The results show that flow behaviors are affected by testing temperature significantly. In order to describe the flow features of AHSS, the Johnson-Cook (JC) model is employed. By introducing polynomial functions to consider the effects of temperature on hardening behavior, the JC model is modified and used to predict flow behavior of AHSS at different experimental conditions. The accuracy of the modified JC model is verified and the predicted flow stress is in good agreement with experimental results, which confirms that the modified JC model can give an accurate and precise estimate over a wide range of temperatures.

  9. Strangeness at high temperatures

    CERN Document Server

    Schmidt, Christian

    2013-01-01

    We use up to fourth order cumulants of net strangeness fluctuations and their correlations with net baryon number fluctuations to extract information on the strange meson and baryon contribution to the low temperature hadron resonance gas, the dissolution of strange hadronic states in the crossover region of the QCD transition and the quasi-particle nature of strange quark contributions to the high temperature quark-gluon plasma phase.

  10. Dynamics of ordering in highly degenerate models with anisotropic grain-boundary potential: Effects of temperature and vortex formation

    DEFF Research Database (Denmark)

    Jeppesen, Claus; Flyvbjerg, Henrik; Mouritsen, Ole G.

    1989-01-01

    Monte Carlo computer-simulation techniques are used to elucidate the equilibrium phase behavior as well as the late-stage ordering dynamics of some two-dimensional models with ground-state ordering of a high degeneracy, Q. The models are Q-state Potts models with anisotropic grain......, like the standard Potts models do, nor a wetting of the boundaries, as the standard clock models do. Thermal fluctuations nevertheless cause wetting to occur for not too small temperatures. Specifically, we have studied models with Q=12 and 48. The models are quenched from infinite to zero as well......, for quenches to finite temperatures in the Potts-ordered phase there is a distinct crossover to the classical Lifshitz-Allen-Cahn exponent value, n=1 / 2, for both values of Q. This supports the conjecture that the zero-temperature dynamics for models with soft domain boundaries belong to a special...

  11. Dynamic modeling and experimental investigation of a high temperature PEM fuel cell stack

    DEFF Research Database (Denmark)

    Nguyen, Gia; Sahlin, Simon Lennart; Andreasen, Søren Juhl;

    2016-01-01

    High temperature polymer fuel cells operating at 100 to 200◦C require simple fuel processing and produce high quality heat that can integrate well with domestic heating systems. Because the transportation of hydrogen is challenging, an alternative option is to reform natural gas on site. This art...

  12. High temperature series expansions for the susceptibility of Ising model on the Kagome lattice with nearest neighber interactions

    Directory of Open Access Journals (Sweden)

    Z Jalali mola

    2011-12-01

    Full Text Available  The Ising model is one of the simplest models describing the interacting particles. In this work, we calculate the high temperature series expansions of zero field susceptibility of ising model with ferromagnetic, antiferromagnetic and one antiferromagnetic interactions on two dimensional kagome lattice. Using the Pade´ approximation, we calculate the susceptibility of critical exponent of ferromagnetic ising model γ ≈ 1.75, which is consistent with universality hypothesis. However, antiferromagnetic and one antiferromagnetic interaction ising model doesn’t show any transition at finite temperature because of the effect of magnetic frustration.

  13. High temperature thermal behaviour modeling of large-scale fused silica optics for laser facility

    Institute of Scientific and Technical Information of China (English)

    Yu Jing-Xia; He Shao-Bo; Xiang Xia; Yuan Xiao-Dong; Zheng Wan-Guo; Lü Hai-Bing; Zu Xiao-Tao

    2012-01-01

    High temperature annealing is often used for the stress control of optical materials.However,weight and viscosity at high temperature may destroy the surface morphology,especially for the large-scale,thin and heavy optics used for large laser facilities.It is necessary to understand the thermal behaviour and design proper support systems for large-scale optics at high temperature.In this work,three support systems for fused silica optics are designed and simulated with the finite element method.After the analysis of the thermal behaviours of different support systems,some advantages and disadvantages can be revealed.The results show that the support with the optical surface vertical is optimal because both pollution and deformation of optics could be well controlled during annealing at high temperature.Annealing process of the optics irradiated by CO2 laser is also simulated.It can be concluded that high temperature annealing can effectively reduce the residual stress.However,the effects of annealing on surface morphology of the optics are complex.Annealing creep is closely related to the residual stress and strain distribution.In the region with large residual stress,the creep is too large and probably increases the deformation gradient which may affect the laser beam propagation.

  14. Projected changes to high temperature events for Canada based on a regional climate model ensemble

    Science.gov (United States)

    Jeong, Dae Il; Sushama, Laxmi; Diro, Gulilat Tefera; Khaliq, M. Naveed; Beltrami, Hugo; Caya, Daniel

    2016-05-01

    Extreme hot spells can have significant impacts on human society and ecosystems, and therefore it is important to assess how these extreme events will evolve in a changing climate. In this study, the impact of climate change on hot days, hot spells, and heat waves, over 10 climatic regions covering Canada, based on 11 regional climate model (RCM) simulations from the North American Regional Climate Change Assessment Program for the June to August summer period is presented. These simulations were produced with six RCMs driven by four Atmosphere-Ocean General Circulation Models (AOGCM), for the A2 emission scenario, for the current 1970-1999 and future 2040-2069 periods. Two types of hot days, namely HD-1 and HD-2, defined respectively as days with only daily maximum temperature (Tmax) and both Tmax and daily minimum temperature (Tmin) exceeding their respective thresholds (i.e., period-of-record 90th percentile of Tmax and Tmin values), are considered in the study. Analogous to these hot days, two types of hot spells, namely HS-1 and HS-2, are identified as spells of consecutive HD-1 and HD-2 type hot days. In the study, heat waves are defined as periods of three or more consecutive days, with Tmax above 32 °C threshold. Results suggest future increases in the number of both types of hot days and hot spell events for the 10 climatic regions considered. However, the projected changes show high spatial variability and are highly dependent on the RCM and driving AOGCM combination. Extreme hot spell events such as HS-2 type hot spells of longer duration are expected to experience relatively larger increases compared to hot spells of moderate duration, implying considerable heat related environmental and health risks. Regionally, the Great Lakes, West Coast, Northern Plains, and Maritimes regions are found to be more affected due to increases in the frequency and severity of hot spells and/or heat wave characteristics, requiring more in depth studies for these regions

  15. Modeling of a Large-Scale High Temperature Regenerative Sulfur Removal Process

    DEFF Research Database (Denmark)

    Konttinen, Jukka T.; Johnsson, Jan Erik

    1999-01-01

    -up. Steady-state kinetic reactor models are needed for reactor sizing, and dynamic models can be used for process control design and operator training. The regenerative sulfur removal process to be studied in this paper consists of two side-by-side fluidized bed reactors operating at temperatures of 400......-650°C and at elevated pressure. In this paper, hydrodynamic modeling equations for dense fluidized bed and freeboard are applied for the prediction of the performance of a large-scale regeneration reactor. These equations can partly explain the differences in modeling results observed with a simpler...

  16. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  17. High temperature storage loop :

    Energy Technology Data Exchange (ETDEWEB)

    Gill, David Dennis; Kolb, William J.

    2013-07-01

    A three year plan for thermal energy storage (TES) research was created at Sandia National Laboratories in the spring of 2012. This plan included a strategic goal of providing test capability for Sandia and for the nation in which to evaluate high temperature storage (>650ÀC) technology. The plan was to scope, design, and build a flow loop that would be compatible with a multitude of high temperature heat transfer/storage fluids. The High Temperature Storage Loop (HTSL) would be reconfigurable so that it was useful for not only storage testing, but also for high temperature receiver testing and high efficiency power cycle testing as well. In that way, HTSL was part of a much larger strategy for Sandia to provide a research and testing platform that would be integral for the evaluation of individual technologies funded under the SunShot program. DOEs SunShot program seeks to reduce the price of solar technologies to 6/kWhr to be cost competitive with carbon-based fuels. The HTSL project sought to provide evaluation capability for these SunShot supported technologies. This report includes the scoping, design, and budgetary costing aspects of this effort

  18. CONSTITUTIVE MODEL OF STEEL FIBRE REINFORCED CONCRETE SUBJECTED TO HIGH TEMPERATURES

    Directory of Open Access Journals (Sweden)

    Lukas Blesak

    2016-12-01

    Full Text Available Research on structural load-bearing systems exposed to elevated temperatures is an active topic in civil engineering. Carrying out a full-size experiment of a specimen exposed to fire is a challenging task considering not only the preparation labour but also the necessary costs. Therefore, such experiments are simulated using various software and computational models in order to predict the structural behaviour as exactly as possible. In this paper such a procedure, focusing on software simulation, is described in detail. The proposed constitutive model is based on the stress-strain curve and allows predicting SFRC material behaviour in bending at ambient and elevated temperature. SFRC material is represented by the initial linear behaviour, an instantaneous drop of stress after the initial crack occurs and its consequent specific ductility, which influences the overall modelled specimen behaviour under subjected loading. The model is calibrated with ATENA FEM software using experimental results.

  19. Desulfurization at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Panula-Nikkilae, E.; Kurkela, E.; Mojtahedi, W.

    1987-01-01

    Two high-temperature desulfurization methods, furnace injection and gasification-desulfurization are presented. In furnace injection, the efficiency of desulfurization is 50-60%, but this method is applied in energy production plants, where flue gas desulfurization cannot be used. Ca-based sorbents are used as desulfurization material. Factors affecting desulfurization and the effect of injection on the boiler and ash handling are discussed. In energy production based on gasification, very low sulfur emissions can be achieved by conventional low-temperature cleanup. However, high-temperature gas cleaning leads to higher efficiency and can be applied to smaller size classes. Ca-, Fe-, or Zn-based sorbents or mixed metals can be used for desulfurization. Most of the methods under development are based on the use of regenerative sorbents in a cleanup reactor located outside the gasifier. So far, only calcium compounds have been used for desulfurization inside the gasifier.

  20. High temperature nanoplasmonics

    Science.gov (United States)

    Alabastri, Alessandro; Toma, Andrea; Malerba, Mario; De Angelis, Francesco; Proietti Zaccaria, Remo

    2016-09-01

    Metallic nanostructures can be utilized as heat nano-sources which can find application in different areas such as photocatalysis, nanochemistry or sensor devices. Here we show how the optical response of plasmonic structures is affected by the increase of temperature. In particular we apply a temperature dependent dielectric function model to different nanoparticles finding that the optical responses are strongly dependent on shape and aspect-ratio. The idea is that when metallic structures interact with an electromagnetic field they heat up due to Joule effect. The corresponding temperature increase modifies the optical response of the particle and thus the heating process. The key finding is that, depending on the structures geometry, absorption efficiency can either increase or decrease with temperature. Since absorption relates to thermal energy dissipation and thus to temperature increase, the mechanism leads to positive or negative loops. Consequently, not only an error would be made by neglecting temperature but it would be not even possible to know, a priori, if the error is towards higher or lower values.

  1. Dark radiation and dark matter in supersymmetric axion models with high reheating temperature

    Energy Technology Data Exchange (ETDEWEB)

    Graf, Peter; Steffen, Frank Daniel, E-mail: graf@mpp.mpg.de, E-mail: steffen@mpp.mpg.de [Max-Planck-Institut für Physik, Föhringer Ring 6, D–80805 Munich (Germany)

    2013-12-01

    Recent studies of the cosmic microwave background, large scale structure, and big bang nucleosynthesis (BBN) show trends towards extra radiation. Within the framework of supersymmetric hadronic axion models, we explore two high-reheating-temperature scenarios that can explain consistently extra radiation and cold dark matter (CDM), with the latter residing either in gravitinos or in axions. In the gravitino CDM case, axions from decays of thermal saxions provide extra radiation already prior to BBN and decays of axinos with a cosmologically required TeV-scale mass can produce extra entropy. In the axion CDM case, cosmological constraints are respected with light eV-scale axinos and weak-scale gravitinos that decay into axions and axinos. These decays lead to late extra radiation which can coexist with the early contributions from saxion decays. Recent results of the Planck satellite probe extra radiation at late times and thereby both scenarios. Further tests are the searches for axions at ADMX and for supersymmetric particles at the LHC.

  2. Modeling high-temperature superconductors and metallic alloys on the intel iPSC/860

    Energy Technology Data Exchange (ETDEWEB)

    Geist, G.A.; Peyton, B.W.; Shelton, W.A.; Stocks, G.M.

    1990-01-01

    Oak Ridge National Laboratory has embarked on several computational Grand Challenges, which require the close cooperation of physicists, mathematicians, and computer scientists. One of these projects is the determination of the material properties of alloys from first principles and, in particular, the electronic structure of high-temperature superconductors. While the present focus of the project is on superconductivity, the approach is general enough to permit study of other properties of metallic alloys such as strength and magnetic properties. This paper describes the progress to date on this project. We include a description of a self-consistent KKR-CPA method, parallelization of the model, and the incorporation of a dynamic load balancing scheme into the algorithm. We also describe the development and performance of a consolidated KKR-CPA code capable of running on CRAYs, workstations, and several parallel computers without source code modification. Performance of this code on the Intel iPSC/860 is also compared to a CRAY 2, CRAY YMP, and several workstations. Finally, some density of state calculations of two perovskite superconductors are given. 10 refs., 4 figs.

  3. Adjustment of mathematical models and quality of soybean grains in the drying with high temperatures

    Directory of Open Access Journals (Sweden)

    Paulo C. Coradi

    2016-04-01

    Full Text Available ABSTRACT The aim of this study was to evaluate the influence of the initial moisture content of soybeans and the drying air temperatures on drying kinetics and grain quality, and find the best mathematical model that fit the experimental data of drying, effective diffusivity and isosteric heat of desorption. The experimental design was completely randomized (CRD, with a factorial scheme (4 x 2, four drying temperatures (75, 90, 105 and 120 ºC and two initial moisture contents (25 and 19% d.b., with three replicates. The initial moisture content of the product interferes with the drying time. The model of Wang and Singh proved to be more suitable to describe the drying of soybeans to temperature ranges of the drying air of 75, 90, 105 and 120 °C and initial moisture contents of 19 and 25% (d.b.. The effective diffusivity obtained from the drying of soybeans was higher (2.5 x 10-11 m2 s-1 for a temperature of 120 °C and water content of 25% (d.b.. Drying of soybeans at higher temperatures (above 105 °C and higher initial water content (25% d.b. also increases the amount of energy (3894.57 kJ kg-1, i.e., the isosteric heat of desorption necessary to perform the process. Drying air temperature and different initial moisture contents affected the quality of soybean along the drying time (electrical conductivity of 540.35 µS cm-1g-1; however, not affect the final yield of the oil extracted from soybean grains (15.69%.

  4. High-temperature thermo-mechanical behavior of functionally graded materials produced by plasma sprayed coating: Experimental and modeling results

    Science.gov (United States)

    Choi, Kang Hyun; Kim, Hyun-Su; Park, Chang Hyun; Kim, Gon-Ho; Baik, Kyoung Ho; Lee, Sung Ho; Kim, Taehyung; Kim, Hyoung Seop

    2016-09-01

    Thermal barrier coatings are widely used in aerospace industries to protect exterior surfaces from harsh environments. In this study, functionally graded materials (FGMs) were investigated with the aim to optimize their high temperature resistance and strength characteristics. NiCrAlY bond coats were deposited on Inconel-617 superalloy substrate specimens by the low vacuum plasma spraying technique. Functionally graded Ni-yttria-stabilized zirconia (YSZ) coatings with gradually varying amounts of YSZ (20%-100%) were fabricated from composite powders by vacuum plasma spraying. Heat shield performance tests were conducted using a high- temperature plasma torch. The temperature distributions were measured using thermocouples at the interfaces of the FGM layers during the tests. A model for predicting the temperature at the bond coating-substrate interface was established. The temperature distributions simulated using the finite element method agreed well with the experimental results.

  5. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie Corinne Scheidt

    1994-01-01

    This thesis presents the on-going development of methodology for a probabilistic material strength degradation model. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes four effects that typically reduce lifetime strength: high temperature, mechanical fatigue, creep, and thermal fatigue. Statistical analysis was conducted on experimental Inconel 718 data obtained from the open literature. This analysis provided regression parameters for use as the model's empirical material constants, thus calibrating the model specifically for Inconel 718. Model calibration was carried out for four variables, namely, high temperature, mechanical fatigue, creep, and thermal fatigue. Methodology to estimate standard deviations of these material constants for input into the probabilistic material strength model was developed. Using the current version of PROMISS, entitled PROMISS93, a sensitivity study for the combined effects of mechanical fatigue, creep, and thermal fatigue was performed. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing a combination of mechanical fatigue and high temperature effects by model to the combination by experiment were conducted. Thus, for Inconel 718, the basic model assumption of independence between effects was evaluated. Results from this limited verification study strongly supported this assumption.

  6. Experimental characterization and mechanical behaviour modelling of molybdenum-titanium carbide composite for high temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Cedat, D.; Libert, M.; Rey, C.; Clavel, M.; Schmitt, J.H. [Ecole Cent Paris, MSSMAT, F-92295 Chatenay Malabry (France); Le Flem, M. [CEA Saclay, DEN, DANS, DMN, SRMA, 91 - Gif-sur-Yvette (France); Fandeur, O. [CEA Saclay, DEN, DANS, DM2S, SEMT, LM2S, 91 - Gif-sur-Yvette (France)

    2009-03-15

    Simulations of the elastic-viscoplastic behaviour of ceramic-metal composite, over the temperature range 298-993 K, are performed on realistic aggregates built up from electron back scatter diffraction methods. Physical based constitutive models are developed in order to characterize the deformation behaviour of body centered cubic (bcc) metal and face centered cubic (fcc) ceramic under various temperatures. While the ceramic keeps elastic, the viscoplastic behaviour of the metal part is described with a dislocation - based model, implemented in the finite element code ABAQUS, in order to compute local strain and stress fields during compressive tests. It is shown that the adopted constitutive laws are able to give back local complex experimental evidence on weak points of the microstructure. (authors)

  7. High ambient temperature reverses hypothalamic MC4 receptor overexpression in an animal model of anorexia nervosa.

    Science.gov (United States)

    Gutiérrez, E; Churruca, I; Zárate, J; Carrera, O; Portillo, M P; Cerrato, M; Vázquez, R; Echevarría, E

    2009-04-01

    The potential involvement of the melanocortin system in the beneficial effects of heat application in rats submitted to activity-based anorexia (ABA), an analogous model of anorexia nervosa (AN), was studied. Once ABA rats had lost 20% of body weight, half of the animals were exposed to a high ambient temperature (HAT) of 32 degrees C, whereas the rest were maintained at 21 degrees C. Control sedentary rats yoked to ABA animals received the same treatment. ABA rats (21 degrees C) showed increased Melanocortin 4 (MC4) receptor and Agouti gene Related Peptide (AgRP) expression, and decreased pro-opiomelanocortin (POMC) mRNA levels (Real Time PCR), with respect to controls. Heat application increased weight gain and food intake, and reduced running rate in ABA rats, when compared with ABA rats at 21 degrees C. However, no changes in body weight and food intake were observed in sedentary rats exposed to heat. Moreover, heat application reduced MC4 receptor, AgRP and POMC expression in ABA rats, but no changes were observed in control rats. These results indicate that hypothalamic MC4 receptor overexpression could occur on the basis of the characteristic hyperactivity, weight loss, and self-starvation of ABA rats, and suggest the involvement of hypothalamic melanocortin neural circuits in behavioural changes shown by AN patients. Changes in AgRP and POMC expression could represent an adaptative response to equilibrate energy balance. Moreover, the fact that HAT reversed hypothalamic MC4 receptor overexpression in ABA rats indicates the involvement of brain melanocortin system in the reported beneficial effects of heat application in AN. A combination of MC4 receptor antagonists and heat application could improve the clinical management of AN.

  8. Atomistic modeling of high temperature uranium-zirconium alloy structure and thermodynamics

    Science.gov (United States)

    Moore, A. P.; Beeler, B.; Deo, C.; Baskes, M. I.; Okuniewski, M. A.

    2015-12-01

    A semi-empirical Modified Embedded Atom Method (MEAM) potential is developed for application to the high temperature body-centered-cubic uranium-zirconium alloy (γ-U-Zr) phase and employed with molecular dynamics (MD) simulations to investigate the high temperature thermo-physical properties of U-Zr alloys. Uranium-rich U-Zr alloys (e.g. U-10Zr) have been tested and qualified for use as metallic nuclear fuel in U.S. fast reactors such as the Integral Fast Reactor and the Experimental Breeder Reactors, and are a common sub-system of ternary metallic alloys like U-Pu-Zr and U-Zr-Nb. The potential was constructed to ensure that basic properties (e.g., elastic constants, bulk modulus, and formation energies) were in agreement with first principles calculations and experimental results. After which, slight adjustments were made to the potential to fit the known thermal properties and thermodynamics of the system. The potentials successfully reproduce the experimental melting point, enthalpy of fusion, volume change upon melting, thermal expansion, and the heat capacity of pure U and Zr. Simulations of the U-Zr system are found to be in good agreement with experimental thermal expansion values, Vegard's law for the lattice constants, and the experimental enthalpy of mixing. This is the first simulation to reproduce the experimental thermodynamics of the high temperature γ-U-Zr metallic alloy system. The MEAM potential is then used to explore thermodynamics properties of the high temperature U-Zr system including the constant volume heat capacity, isothermal compressibility, adiabatic index, and the Grüneisen parameters.

  9. Utilization of high temperature compost in space agriculture: the model compost kills Escherichia coli

    Science.gov (United States)

    Oshima, Tairo; Moriya, Toshiyuki; Yoshii, Takahiro

    The author and his colleagues have proposed the use of high temperature composting in space inhabitation. Composting has many advantages over burning in organic waste treatments. Composting is self-heating processes and needs no extra fuel. Composting requires no sophis-ticated equipment such as an incinerator. Composting emits no hazardous gases such as NOx, SOx and dioxines which are often produced by burning. The final product can be used as fer-tilizer in space farm land; resources recycling society can be constructed in space stations and space cities. In addition to these advantages, composting and compost soil may contribute to the environmental cleanup. During composting processes, harmful compounds to agricultural plants and animals can be destroyed. Seeds of weeds can be killed by high heat. Likewise pathogenic microbes in the waste can be eliminated during fermentation inside the composts. Recently we measured the survivability of E. coli in compost. E. coli was used as the represen-tative of the Gram-negative bacteria. Since many pathogenic strains belong to Gram-negative bacteria and Gram-negative bacteria are more resistant to antibiotics than gram-positive bac-teria. When E. coli cells were mixed in the compost pile of which inside temperature reaches up to 75oC, they died within a short period as expected. However, E. coli DNA was detected even after a day in high temperature compost. RNA has a shorter life-span than DNA, but was detected after incubation in compost for several hours. In addition to sterilizing effects due to high temperature, we found our compost soil has E. coli killing activity. When mixed with the compost soil at room temperature, E. coli died gradually. Extract of the compost soil also killed E. coli at room temperature, but it took a few days to eliminate E. coli completely. During the killing process, total number of living bacteria did not change, indicating that the killing activity is limited to some specific

  10. Nonlinear plasmonics at high temperatures

    CERN Document Server

    Sivan, Yonatan

    2016-01-01

    We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on {\\em experimentally}-measured data for the metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution, and thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modelling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high temperature non...

  11. Nonlinear plasmonics at high temperatures

    Directory of Open Access Journals (Sweden)

    Sivan Yonatan

    2017-01-01

    Full Text Available We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW illumination. Unlike previous studies, we rely on experimentally-measured data for metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution and, thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modeling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high-temperature nonlinear plasmonics, especially for refractory metals, for both CW and pulsed illumination.

  12. Nonlinear plasmonics at high temperatures

    Science.gov (United States)

    Sivan, Yonatan; Chu, Shi-Wei

    2017-01-01

    We solve the Maxwell and heat equations self-consistently for metal nanoparticles under intense continuous wave (CW) illumination. Unlike previous studies, we rely on experimentally-measured data for metal permittivity for increasing temperature and for the visible spectral range. We show that the thermal nonlinearity of the metal can lead to substantial deviations from the predictions of the linear model for the temperature and field distribution and, thus, can explain qualitatively the strong nonlinear scattering from such configurations observed experimentally. We also show that the incompleteness of existing data of the temperature dependence of the thermal properties of the system prevents reaching a quantitative agreement between the measured and calculated scattering data. This modeling approach is essential for the identification of the underlying physical mechanism responsible for the thermo-optical nonlinearity of the metal and should be adopted in all applications of high-temperature nonlinear plasmonics, especially for refractory metals, for both CW and pulsed illumination.

  13. High temperature superconducting compounds

    Science.gov (United States)

    Goldman, Allen M.

    1992-11-01

    The major accomplishment of this grant has been to develop techniques for the in situ preparation of high-Tc superconducting films involving the use of ozone-assisted molecular beam epitaxy. The techniques are generalizable to the growth of trilayer and multilayer structures. Films of both the DyBa2Cu3O(7-x) and YBa2Cu3O(7-x) compounds as well as the La(2-x)Sr(x)CuO4 compound have been grown on the usual substrates, SrTiO3, YSZ, MgO, and LaAlO3, as well as on Si substrates without any buffer layer. A bolometer has been fabricated on a thermally isolated SiN substrate coated with YSZ, an effort carried out in collaboration with Honeywell Inc. The deposition process facilitates the fabrication of very thin and transparent films creating new opportunities for the study of superconductor-insulator transitions and the investigation of photo-doping with carriers of high temperature superconductors. In addition to a thin film technology, a patterning technology has been developed. Trilayer structures have been developed for FET devices and tunneling junctions. Other work includes the measurement of the magnetic properties of bulk single crystal high temperature superconductors, and in collaboration with Argonne National Laboratory, measurement of electric transport properties of T1-based high-Tc films.

  14. High Temperature Piezoelectric Drill

    Science.gov (United States)

    Bao, Xiaoqi; Bar-Cohen, Yoseph; Sherrit, Stewart; Badescu, Mircea; Shrout, Tom

    2012-01-01

    Venus is one of the planets in the solar systems that are considered for potential future exploration missions. It has extreme environment where the average temperature is 460 deg C and its ambient pressure is about 90 atm. Since the existing actuation technology cannot maintain functionality under the harsh conditions of Venus, it is a challenge to perform sampling and other tasks that require the use of moving parts. Specifically, the currently available electromagnetic actuators are limited in their ability to produce sufficiently high stroke, torque, or force. In contrast, advances in developing electro-mechanical materials (such as piezoelectric and electrostrictive) have enabled potential actuation capabilities that can be used to support such missions. Taking advantage of these materials, we developed a piezoelectric actuated drill that operates at the temperature range up to 500 deg C and the mechanism is based on the Ultrasonic/Sonic Drill/Corer (USDC) configuration. The detailed results of our study are presented in this paper

  15. FAILURE MODE AND CONSTITUTIVE MODEL OF PLAIN HIGH-STRENGTH HIGH-PERFORMANCE CONCRETE UNDER BIAXIAL COMPRESSION AFTER EXPOSURE TO HIGH TEMPERATURES

    Institute of Scientific and Technical Information of China (English)

    Zhenjun He; Yupu Song

    2008-01-01

    An orthotropic constitutive relationship with temperature parameters for plain highstrength high-performance concrete (HSHPC) under biaxial compression is developed. It is based on the experiments performed for characterizing the strength and deformation behavior at two strength levels of HSHPC at 7 different stress ratios including α = σ2 : σ3 = 0.00 : -1, -0.20 : -1, -0.30 : -1, -0.40 : -1, -0.50 : -1, -0.75 : -1, -1.00 : -1, after the exposure to normal and high temperatures of 20, 200, 300, 400, 500 and 600℃, and using a large static-dynamic true triaxial machine. The biaxial tests were performed on 100 mm × 100 mm × 100 mm cubic specimens, and friction-reducing pads were used consisting of three layers of plastic membrane with glycerine in-between for the compressive loading plane. Based on the experimental results, failure modes of HSHPC specimens were described. The principal static compressive strengths, strains at the peak stress and stress-strain curves were measured; and the influence of the temperature and stress ratios on them was also analyzed. The experimental results showed that the uniaxial compressive strength of plain HSHPC after exposure to high temperatures does not decrease dramatically with the increase of temperature. The ratio of the biaxial to its uniaxial compressive strength depends on the stress ratios and brittleness-stiffness of HSHPC after exposure to different temperature levels. Comparison of the stress-strain results obtained from the theoretical model and the experimental data indicates good agreement.

  16. High temperature materials and mechanisms

    CERN Document Server

    2014-01-01

    The use of high-temperature materials in current and future applications, including silicone materials for handling hot foods and metal alloys for developing high-speed aircraft and spacecraft systems, has generated a growing interest in high-temperature technologies. High Temperature Materials and Mechanisms explores a broad range of issues related to high-temperature materials and mechanisms that operate in harsh conditions. While some applications involve the use of materials at high temperatures, others require materials processed at high temperatures for use at room temperature. High-temperature materials must also be resistant to related causes of damage, such as oxidation and corrosion, which are accelerated with increased temperatures. This book examines high-temperature materials and mechanisms from many angles. It covers the topics of processes, materials characterization methods, and the nondestructive evaluation and health monitoring of high-temperature materials and structures. It describes the ...

  17. Measurements and Modeling of III-V Solar Cells at High Temperatures up to 400 degrees C

    Energy Technology Data Exchange (ETDEWEB)

    Perl, Emmett E.; Simon, John; Geisz, John F.; Lee, Minjoo Larry; Friedman, Daniel J.; Steiner, Myles A.

    2016-09-01

    In this paper, we study the performance of 2.0 eV Al0.12Ga0.39In0.49P and 1.4 eV GaAs solar cells over a temperature range of 25-400 degrees C. The temperature-dependent J01 and J02 dark currents are extracted by fitting current-voltage measurements to a two-diode model. We find that the intrinsic carrier concentration ni dominates the temperature dependence of the dark currents, open-circuit voltage, and cell efficiency. To study the impact of temperature on the photocurrent and bandgap of the solar cells, we measure the quantum efficiency and illuminated current-voltage characteristics of the devices up to 400 degrees C. As the temperature is increased, we observe no degradation to the internal quantum efficiency and a decrease in the bandgap. These two factors drive an increase in the short-circuit current density at high temperatures. Finally, we measure the devices at concentrations ranging from ~30 to 1500 suns and observe n = 1 recombination characteristics across the entire temperature range. These findings should be a valuable guide to the design of any system that requires high-temperature solar cell operation.

  18. Experimental characterization and mechanical behaviour modelling of MoTiC composite for high temperature applications

    Energy Technology Data Exchange (ETDEWEB)

    Cedat, D.; Rey, C.; Clavel, M.; Schmitt, J.H. (MSSMAT, CNRS, Chatenay-Malabry (France)); Fandeur, O. (CEA DEN/DANS/DM2S/SEMT/LM2S, Gif-sur-Yvette (France)); Le Flem, M. (CEA DEN/DANS/DMN/SRMA, Gif-sur-Yvette (France))

    2008-10-15

    Simulations of the elastic-viscoplastic behaviour of ceramic-metal composite, over the temperature range 298-993K, are performed on realistic aggregates built up from Electron Back Scatter Diffraction methods. While the ceramic keeps elastic, the viscoplastic behaviour of the metal part is described with a dislocation-based model, implemented in the finite element code ABAQUS, in order to compute local strain and stress fields during compressive tests. It is shown that the adopted constitutive laws are able to give back local complex experimental evidence on weak points of the microstructure. (au)

  19. High temperature superconductors

    CERN Document Server

    Paranthaman, Parans

    2010-01-01

    This essential reference provides the most comprehensive presentation of the state of the art in the field of high temperature superconductors. This growing field of research and applications is currently being supported by numerous governmental and industrial initiatives in the United States, Asia and Europe to overcome grid energy distribution issues. The technology is particularly intended for densely populated areas. It is now being commercialized for power-delivery devices, such as power transmission lines and cables, motors and generators. Applications in electric utilities include current limiters, long transmission lines and energy-storage devices that will help industries avoid dips in electric power.

  20. Uncertainty in a Markov state model with missing states and rates: Application to a room temperature kinetic model obtained using high temperature molecular dynamics.

    Science.gov (United States)

    Chatterjee, Abhijit; Bhattacharya, Swati

    2015-09-21

    Several studies in the past have generated Markov State Models (MSMs), i.e., kinetic models, of biomolecular systems by post-analyzing long standard molecular dynamics (MD) calculations at the temperature of interest and focusing on the maximally ergodic subset of states. Questions related to goodness of these models, namely, importance of the missing states and kinetic pathways, and the time for which the kinetic model is valid, are generally left unanswered. We show that similar questions arise when we generate a room-temperature MSM (denoted MSM-A) for solvated alanine dipeptide using state-constrained MD calculations at higher temperatures and Arrhenius relation — the main advantage of such a procedure being a speed-up of several thousand times over standard MD-based MSM building procedures. Bounds for rate constants calculated using probability theory from state-constrained MD at room temperature help validate MSM-A. However, bounds for pathways possibly missing in MSM-A show that alternate kinetic models exist that produce the same dynamical behaviour at short time scales as MSM-A but diverge later. Even in the worst case scenario, MSM-A is found to be valid longer than the time required to generate it. Concepts introduced here can be straightforwardly extended to other MSM building techniques.

  1. Comparison of Stream Temperature Modeling Approaches: The Case of a High Alpine Watershed in the Context of Climate Change

    Science.gov (United States)

    Gallice, A.

    2015-12-01

    Stream temperature controls important aspects of the riverine habitat, such as the rate of spawning or death of many fish species, or the concentration of numerous dissolved substances. In the current context of accelerating climate change, the future evolution of stream temperature is regarded as uncertain, particularly in the Alps. This uncertainty fostered the development of many prediction models, which are usually classified in two categories: mechanistic models and statistical models. Based on the numerical resolution of physical conservation laws, mechanistic models are generally considered to provide more reliable long-term estimates than regression models. However, despite their physical basis, these models are observed to differ quite significantly in some aspects of their implementation, notably (1) the routing of water in the river channel and (2) the estimation of the temperature of groundwater discharging into the stream. For each one of these two aspects, we considered several of the standard modeling approaches reported in the literature and implemented them in a new modular framework. The latter is based on the spatially-distributed snow model Alpine3D, which is essentially used in the framework to compute the amount of water infiltrating in the upper soil layer. Starting from there, different methods can be selected for the computation of the water and energy fluxes in the hillslopes and in the river network. We relied on this framework to compare the various methodologies for river channel routing and groundwater temperature modeling. We notably assessed the impact of each these approaches on the long-term stream temperature predictions of the model under a typical climate change scenario. The case study was conducted over a high Alpine catchment in Switzerland, whose hydrological and thermal regimes are expected to be markedly affected by climate change. The results show that the various modeling approaches lead to significant differences in the

  2. Fractal model for evaluating heat transfer of high temperature porous corundum shell in vacuum investment casting

    Directory of Open Access Journals (Sweden)

    WAN Xin

    2006-02-01

    Full Text Available Under vacuum, heat transfer in porous corundum shell of investment casting depends on the characteristics of the solid materials and the spatial arrangement of solids and pores. In this study, we present a modified fractal approach to model the pore structure of corundum shell and to describe its influence on the thermal conductivity. We assumed that there is no heat convection in the shell. A sectioned view of porous corundum shell was studied and used to describe the geometric structure and to calculate the fractal dimension d. Based on the fractal dimension d, we obtained the relationship between volumetric solid content and pore arrangement in different measure scales. A heat transfer model was thus established using a network of resistors in which we applied an equivalent approach to calculate the effective thermal conductivity of real porous corundum shell that include the effects of heat conduction and heat radiation of solid. From the obtained results we discuss these effects on the effective thermal conductivity including the scale of measurement, the structure of pore and the temperature. At last these results were compared with other empirical model, which computed by assuming even porosity in which effect of pore structure was not being considered. Though the thermal conductivity calculated essentially in agreement with that obtained from empirical model, model used in this study is more close to the real heat transfer process.

  3. Modeling of Intrinsic Josephson Junctions in High Temperature Superconductors under External Radiation in the Breakpoint Region

    Directory of Open Access Journals (Sweden)

    Shukrinov Yu. M.

    2016-01-01

    Full Text Available The current-voltage (IV characteristics of the intrinsic Josephson junctions in high temperature superconductors under external electromagnetic radiation are calculated numerically in the parametric resonance region. We discuss a numerical method for calculation of the Shapiro step width on the amplitude of radiation. In order to accelerate computations we used parallelization by task parameter via Simple Linux Utility for Resource Management (SLURM arrays and tested it in the case of a single junction. An analysis of the junction transitions between rotating and oscillating states in the branching region of IV-characteristics is presented.

  4. Modeling of Intrinsic Josephson Junctions in High Temperature Superconductors under External Radiation in the Breakpoint Region

    Science.gov (United States)

    Shukrinov, Yu. M.; Rahmonov, I. R.; Plecenik, A.; Streltsova, O. I.; Zuev, M. I.; Ososkov, G. A.

    2016-02-01

    The current-voltage (IV) characteristics of the intrinsic Josephson junctions in high temperature superconductors under external electromagnetic radiation are calculated numerically in the parametric resonance region. We discuss a numerical method for calculation of the Shapiro step width on the amplitude of radiation. In order to accelerate computations we used parallelization by task parameter via Simple Linux Utility for Resource Management (SLURM) arrays and tested it in the case of a single junction. An analysis of the junction transitions between rotating and oscillating states in the branching region of IV-characteristics is presented.

  5. Modeling and experimental evaluation of the thermal insulation properties of mineral wool products at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dianous, P. de [Isover Saint-Gobain, Rantigny (France). Thermal Lab.; Pincemin, F. [Saint-Gobain Recherche, Aubervilliers (France); Boulet, P.; Jeandel, G. [LEMTA, Vandoeuvre Les Nancy (France). Faculte des Sciences

    1997-11-01

    The authors have studied radiative transfer through insulating materials made of fibers and slugs (modeled respectively as infinite cylinders and spheres) at elevated temperatures. The same theoretical analysis is used for both fibers and spheres. Kerker-Mie theory is applied to determine the radiative coefficients of each type of particle, from the bulk glass complex refractive index and the fiber and slug diameter spectrum. Average radiative coefficients are determined for both fibers and slugs. The independent scattering hypothesis enables the authors to derive the total radiative coefficients of the whole material using a mass weighted average. The radiative transfer equation is solved for a one-dimensional problem, using the multiflux approximation. The conductive part is determined using a semi-empirical formula. The coupling between conduction and radiation is accounted for. This radiative model is applied to mineral wool products at room and elevated temperatures (400 C). Materials made of glass or rock fibers are considered. Special attention is given to fibrous materials with slugs. The authors show that radiative heat transfer reaches a minimum for given fiber and slug diameters. They study the respective contribution of fibers and slugs to radiative transfer as a function of the mean diameter and the amount of slugs present in the fibrous material. Calculated fluxes are compared to experimental ones measured on industrial rock and glass wool products for temperatures ranging from 24 to 400 C. The calculations are performed using the diameter spectra of fibers and slugs measured for these products. The influence of fiber orientation is also studied to better fit experimental data.

  6. Effect of Friction Models and Parameters on the Lagrangian Flow Fields in High-Temperature Compression Testing

    Science.gov (United States)

    Kundalkar, Deepak; Singh, Rajkumar; Tewari, Asim

    2017-07-01

    Friction plays an important role in high-temperature deformation process. Friction affects local displacement field in the tool-workpiece interface region, thus affecting the overall material flow. Under high-temperature compression, macro-indicators like bulge radius and load displacement curves are not sensitive enough to distinguish subtle differences between various friction models. Hence, a new approach to match the experimental Lagrangian flow field with flow field obtained from FE simulation is proposed. For this uniaxial barreling, compression tests at constant temperature were conducted on Gleeble thermo-mechanical simulator. The compression tests were conducted at different strain, strain rate and friction conditions. Finite element simulations employing various friction models and parameters were performed for matching the experimental conditions. Experimental Lagrangian flow fields were obtained from the grain flow lines observed on high-resolution larger area micrographs of the specimen. It was observed that all the investigated friction models provided equally good fit with the macro-experimental indicators (bulge radius and load displacement curves). However, Coulomb friction model was the only friction model that provided the closest fit with the experimentally obtained Lagrangian flow fields. Coulomb friction model provided the best agreement between experimental and numerical simulation for both lubricated and non-lubricated conditions using friction coefficients μ = 0.2993 and μ = 0.3895, respectively.

  7. Modeling of High Temperature Oxidation Behavior of FeCrAl Alloy by using Artificial Neural Network

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jae Joon; Ryu, Ho Jin [KAIST, Daejeon (Korea, Republic of)

    2016-10-15

    Refractory alloys are candidate materials for replacing current zirconium-base cladding of light water reactors and they retain significant creep resistance and mechanical strength at high temperatures up to 1500 ℃ due to their high melting temperature. Thermal neutron cross sections of refractory metals are higher than that of zirconium, however the loss of neutron can be overcome by reducing cladding thickness which can be facilitated with enhanced mechanical properties. However, most refractory metals show the poor oxidation resistance at a high temperature. Oxidation behaviors of the various compositions of FeCrAl alloys in high temperature conditions were modeled by using Bayesian neural network. The automatic relevance determination (ARD) technique represented the influence of the composition of alloying elements on the oxidation resistance of FeCrAl alloys. This model can be utilized to understand the tendency of oxidation behavior along the composition of each element and prove the applicability of neural network modeling for the development of new cladding material of light water reactors.

  8. High temperature interface superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Gozar, A., E-mail: adrian.gozar@yale.edu [Yale University, New Haven, CT 06511 (United States); Bozovic, I. [Yale University, New Haven, CT 06511 (United States); Brookhaven National Laboratory, Upton, NY 11973 (United States)

    2016-02-15

    Highlight: • This review article covers the topic of high temperature interface superconductivity. • New materials and techniques used for achieving interface superconductivity are discussed. • We emphasize the role played by the differences in structure and electronic properties at the interface with respect to the bulk of the constituents. - Abstract: High-T{sub c} superconductivity at interfaces has a history of more than a couple of decades. In this review we focus our attention on copper-oxide based heterostructures and multi-layers. We first discuss the technique, atomic layer-by-layer molecular beam epitaxy (ALL-MBE) engineering, that enabled High-T{sub c} Interface Superconductivity (HT-IS), and the challenges associated with the realization of high quality interfaces. Then we turn our attention to the experiments which shed light on the structure and properties of interfacial layers, allowing comparison to those of single-phase films and bulk crystals. Both ‘passive’ hetero-structures as well as surface-induced effects by external gating are discussed. We conclude by comparing HT-IS in cuprates and in other classes of materials, especially Fe-based superconductors, and by examining the grand challenges currently laying ahead for the field.

  9. CFD modeling and experimental validation of heat and mass transfer in wood poles subjected to high temperatures: a conjugate approach

    Science.gov (United States)

    Younsi, R.; Kocaefe, D.; Poncsak, S.; Kocaefe, Y.; Gastonguay, L.

    2008-03-01

    In this article, a coupling method is presented in the case of high thermal treatment of a wood pole and a three-dimensional numerical simulation is proposed. The conservation equations for the wood sample are obtained using diffusion equation with variables diffusion coefficients and the incompressible Reynolds averaged Navier Stokes equations have been solved for the flow field. The connection between the two problems is achieved by expressing the continuity of the state variables and their respective fluxes through the interface. Turbulence closure is obtained by the use of the standard k ɛ model with the usual wall function treatment. The model equations are solved numerically by the commercial package ANSYS-CFX10. The wood pole was subjected to high temperature treatment under different operating conditions. The model validation is carried out via a comparison between the predicted values with those obtained experimentally. The comparison of the numerical and experimental results shows good agreement, implying that the proposed numerical algorithm can be used as a useful tool in designing high-temperature wood treatment processes. A parametric study was also carried out to determine the effects of several parameters such as initial moisture content, wood aspect ratio and final gas temperature on temperature and moisture content distributions within the samples during heat treatment.

  10. CFD Model Development and validation for High Temperature Gas Cooled Reactor Cavity Cooling System (RCCS) Applications

    Energy Technology Data Exchange (ETDEWEB)

    Hassan, Yassin [Univ. of Wisconsin, Madison, WI (United Texas A & M Univ., College Station, TX (United States); Corradini, Michael; Tokuhiro, Akira; Wei, Thomas Y.C.

    2014-07-14

    The Reactor Cavity Cooling Systems (RCCS) is a passive safety system that will be incorporated in the VTHR design. The system was designed to remove the heat from the reactor cavity and maintain the temperature of structures and concrete walls under desired limits during normal operation (steady-state) and accident scenarios. A small scale (1:23) water-cooled experimental facility was scaled, designed, and constructed in order to study the complex thermohydraulic phenomena taking place in the RCCS during steady-state and transient conditions. The facility represents a portion of the reactor vessel with nine stainless steel coolant risers and utilizes water as coolant. The facility was equipped with instrumentation to measure temperatures and flow rates and a general verification was completed during the shakedown. A model of the experimental facility was prepared using RELAP5-3D and simulations were performed to validate the scaling procedure. The experimental data produced during the steady-state run were compared with the simulation results obtained using RELAP5-3D. The overall behavior of the facility met the expectations. The facility capabilities were confirmed to be very promising in performing additional experimental tests, including flow visualization, and produce data for code validation.

  11. HIgh Temperature Photocatalysis over Semiconductors

    Science.gov (United States)

    Westrich, Thomas A.

    Due in large part to in prevalence of solar energy, increasing demand of energy production (from all sources), and the uncertain future of petroleum energy feedstocks, solar energy harvesting and other photochemical systems will play a major role in the developing energy market. This dissertation focuses on a novel photochemical reaction process: high temperature photocatalysis (i.e., photocatalysis conducted above ambient temperatures, T ≥ 100°C). The overarching hypothesis of this process is that photo-generated charge carriers are able to constructively participate in thermo-catalytic chemical reactions, thereby increasing catalytic rates at one temperature, or maintaining catalytic rates at lower temperatures. The photocatalytic oxidation of carbon deposits in an operational hydrocarbon reformer is one envisioned application of high temperature photocatalysis. Carbon build-up during hydrocarbon reforming results in catalyst deactivation, in the worst cases, this was shown to happen in a period of minutes with a liquid hydrocarbon. In the presence of steam, oxygen, and above-ambient temperatures, carbonaceous deposits were photocatalytically oxidized over very long periods (t ≥ 24 hours). This initial experiment exemplified the necessity of a fundamental assessment of high temperature photocatalytic activity. Fundamental understanding of the mechanisms that affect photocatalytic activity as a function of temperatures was achieved using an ethylene photocatalytic oxidation probe reaction. Maximum ethylene photocatalytic oxidation rates were observed between 100 °C and 200 °C; the maximum photocatalytic rates were approximately a factor of 2 larger than photocatalytic rates at ambient temperatures. The loss of photocatalytic activity at temperatures above 200 °C is due to a non-radiative multi-phonon recombination mechanism. Further, it was shown that the fundamental rate of recombination (as a function of temperature) can be effectively modeled as a

  12. High temperature air-blown woody biomass gasification model for the estimation of an entrained down-flow gasifier.

    Science.gov (United States)

    Kobayashi, Nobusuke; Tanaka, Miku; Piao, Guilin; Kobayashi, Jun; Hatano, Shigenobu; Itaya, Yoshinori; Mori, Shigekatsu

    2009-01-01

    A high temperature air-blown gasification model for woody biomass is developed based on an air-blown gasification experiment. A high temperature air-blown gasification experiment on woody biomass in an entrained down-flow gasifier is carried out, and then the simple gasification model is developed based on the experimental results. In the experiment, air-blown gasification is conducted to demonstrate the behavior of this process. Pulverized wood is used as the gasification fuel, which is injected directly into the entrained down-flow gasifier by the pulverized wood banner. The pulverized wood is sieved through 60 mesh and supplied at rates of 19 and 27kg/h. The oxygen-carbon molar ratio (O/C) is employed as the operational condition instead of the air ratio. The maximum temperature achievable is over 1400K when the O/C is from 1.26 to 1.84. The results show that the gas composition is followed by the CO-shift reaction equilibrium. Therefore, the air-blown gasification model is developed based on the CO-shift reaction equilibrium. The simple gasification model agrees well with the experimental results. From calculations in large-scale units, the cold gas is able to achieve 80% efficiency in the air-blown gasification, when the woody biomass feedrate is over 1000kg/h and input air temperature is 700K.

  13. High temperature interfacial superconductivity

    Science.gov (United States)

    Bozovic, Ivan [Mount Sinai, NY; Logvenov, Gennady [Port Jefferson Station, NY; Gozar, Adrian Mihai [Port Jefferson, NY

    2012-06-19

    High-temperature superconductivity confined to nanometer-scale interfaces has been a long standing goal because of potential applications in electronic devices. The spontaneous formation of a superconducting interface in bilayers consisting of an insulator (La.sub.2CuO.sub.4) and a metal (La.sub.1-xSr.sub.xCuO.sub.4), neither of which is superconducting per se, is described. Depending upon the layering sequence of the bilayers, T.sub.c may be either .about.15 K or .about.30 K. This highly robust phenomenon is confined to within 2-3 nm around the interface. After exposing the bilayer to ozone, T.sub.c exceeds 50 K and this enhanced superconductivity is also shown to originate from a 1 to 2 unit cell thick interfacial layer. The results demonstrate that engineering artificial heterostructures provides a novel, unconventional way to fabricate stable, quasi two-dimensional high T.sub.c phases and to significantly enhance superconducting properties in other superconductors. The superconducting interface may be implemented, for example, in SIS tunnel junctions or a SuFET.

  14. 2000 Lilienfeld Prize Talk - From Model Magnets to High Temperature Superconductors

    Science.gov (United States)

    Birgeneau, Robert J.

    2000-03-01

    Magnetic materials often provide simple and clean examples of important problems in statistical physics. In recent years, much attention has been focussed on one and two dimensional Heisenberg spin systems in which quantum fluctuations play an essential role. Of particular interest are the two dimensional CuO2 Heisenberg square lattice antiferromagnets which, on doping with holes or electrons, become high temperature superconductors. We will review the results of experiments and quantum Monte Carlo calculations on one and two dimensional quantum magnets. We shall also discuss recent neutron studies of the novel incommensurate magnetic structures that occur in the spin glass and superconducting phases of the doped La2CuO4 system. We shall emphasize, in particular, the newly discovered one dimensional spin modulations in the spin glass phase together with the reorientation transition which coincides with the insulator to superconducting transition.

  15. Probabilistic Material Strength Degradation Model for Inconel 718 Components Subjected to High Temperature, High-Cycle and Low-Cycle Mechanical Fatigue, Creep and Thermal Fatigue Effects

    Science.gov (United States)

    Bast, Callie C.; Boyce, Lola

    1995-01-01

    The development of methodology for a probabilistic material strength degradation is described. The probabilistic model, in the form of a postulated randomized multifactor equation, provides for quantification of uncertainty in the lifetime material strength of aerospace propulsion system components subjected to a number of diverse random effects. This model is embodied in the computer program entitled PROMISS, which can include up to eighteen different effects. Presently, the model includes five effects that typically reduce lifetime strength: high temperature, high-cycle mechanical fatigue, low-cycle mechanical fatigue, creep and thermal fatigue. Results, in the form of cumulative distribution functions, illustrated the sensitivity of lifetime strength to any current value of an effect. In addition, verification studies comparing predictions of high-cycle mechanical fatigue and high temperature effects with experiments are presented. Results from this limited verification study strongly supported that material degradation can be represented by randomized multifactor interaction models.

  16. Use of internal variable models to predict the high temperature behaviour of a 6xxx industrial alloy

    Energy Technology Data Exchange (ETDEWEB)

    Gehanno, H. [Centre de Recherches du Groupe Pechiney, 38 - Voreppe (France); Brechet, Y. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Saint-Martin-d`Heres (France); Bechet, D. [Centre de Recherches du Groupe Pechiney, 38 - Voreppe (France); Louchet, F. [Ecole Nationale Superieure d`Electrochimie et d`Electrometallurgie, 38 - Saint-Martin-d`Heres (France)

    1996-12-01

    In this study, we have used the internal variables models in the case of an industrial 6063 alloy. The alloy has been studied in two different conditions (T5 and overaged) and at three different temperatures: 175 C, 250 C and 300 C. The microstructure of the alloy has been thoroughly studied and especially the precipitation state. Then the mechanical behaviour at high temperature has been characterised using different types of tests (creep tests, strain-rate jumps tests and tensile tests at constant strain-rate). With this method, it is possible to study the high temperature steady state behaviour over a wide range of strain-rates. We were also able to describe the transient behaviours and to predict creep curves from tensile tests data with no adjustable parameters. (orig.)

  17. Spatial variability of the Black Sea surface temperature from high resolution modeling and satellite measurements

    Science.gov (United States)

    Mizyuk, Artem; Senderov, Maxim; Korotaev, Gennady

    2016-04-01

    Large number of numerical ocean models were implemented for the Black Sea basin during last two decades. They reproduce rather similar structure of synoptical variability of the circulation. Since 00-s numerical studies of the mesoscale structure are carried out using high performance computing (HPC). With the growing capacity of computing resources it is now possible to reconstruct the Black Sea currents with spatial resolution of several hundreds meters. However, how realistic these results can be? In the proposed study an attempt is made to understand which spatial scales are reproduced by ocean model in the Black Sea. Simulations are made using parallel version of NEMO (Nucleus for European Modelling of the Ocean). A two regional configurations with spatial resolutions 5 km and 2.5 km are described. Comparison of the SST from simulations with two spatial resolutions shows rather qualitative difference of the spatial structures. Results of high resolution simulation are compared also with satellite observations and observation-based products from Copernicus using spatial correlation and spectral analysis. Spatial scales of correlations functions for simulated and observed SST are rather close and differs much from satellite SST reanalysis. Evolution of spectral density for modelled SST and reanalysis showed agreed time periods of small scales intensification. Using of the spectral analysis for satellite measurements is complicated due to gaps. The research leading to this results has received funding from Russian Science Foundation (project № 15-17-20020)

  18. Analysis of Fluid Flow and Heat Transfer Model for the Pebble Bed High Temperature Gas Cooled Reactor

    Directory of Open Access Journals (Sweden)

    S. Yamoah

    2012-06-01

    Full Text Available The pebble bed type high temperature gas cooled nuclear reactor is a promising option for next generation reactor technology and has the potential to provide high efficiency and cost effective electricity generation. The reactor unit heat transfer poses a challenge due to the complexity associated with the thermalflow design. Therefore to reliably simulate the flow and heat transport of the pebble bed modular reactor necessitates a heat transfer model that deals with radiation as well as thermal convection and conduction. In this study, a model with the capability to simulate fluid flow and heat transfer in the pebble bed modular reactor core has been developed. The developed model was implemented on a personal computer using FORTRAN 95 programming language. Several important fluid flow and heat transfer parameters have been examined: including the pressure drop over the reactor core, the heat transfer coefficient, the Nusselt number and the effective thermal conductivity of the fuel pebbles. Results obtained from the simulation experiments show a uniform pressure in the radial direction for a core to fuel element diameter (D/d ratio>20 and the heat transfer coefficient increases with increasing temperature and coolant mass flow rate. The model can adequately account for the flow and heat transfer phenomenon and the loss of pressure through friction in the pebble bed type high temperature nuclear reactor.

  19. High-temperature thermocline TES combining sensible and latent heat - CFD modeling and experimental validation

    Science.gov (United States)

    Zavattoni, Simone A.; Geissbühler, Lukas; Barbato, Maurizio C.; Zanganeh, Giw; Haselbacher, Andreas; Steinfeld, Aldo

    2017-06-01

    The concept of combined sensible/latent heat thermal energy storage (TES) has been exploited to mitigate an intrinsic thermocline TES systems drawback of heat transfer fluid outflow temperature reduction during discharging. In this study, the combined sensible/latent TES prototype under investigation is constituted by a packed bed of rocks and a small amount of encapsulated phase change material (AlSi12) as sensible heat and latent heat sections respectively. The thermo-fluid dynamics behavior of the combined TES prototype was analyzed by means of a computational fluid dynamics approach. Due to the small value of the characteristic vessel-to-particles diameter ratio, the effect of radial void-fraction variation, also known as channeling, was accounted for. Both the sensible and the latent heat sections of the storage were modeled as porous media under the assumption of local thermal non-equilibrium (LTNE). The commercial code ANSYS Fluent 15.0 was used to solve the model's constitutive conservation and transport equations obtaining a fairly good agreement with reference experimental measurements.

  20. Modelling of high-temperature dark current in multi-quantum well structures from MWIR to VLWIR

    Science.gov (United States)

    de Moura Pedroso, Diogo; Vieira, Gustavo Soares; Passaro, Angelo

    2017-02-01

    In this paper, a model to calculate the dark current of quantum well infrared photodetectors at high-temperature regime is presented. The model is derived from a positive-definite quantum probability-flux and considers thermionic emission and thermally-assisted tunnelling as mechanisms of dark current generation. Its main input data are the wave functions obtained by time-independent Schrodinger equation and it does not require empirical parameters related to the transport of carriers. By means of this model, the dark current of quantum well infrared photodetectors at high-temperature regime is investigated with respect to the temperature, the barrier width, the applied electric field and the position of the first excited state. The theoretical results are compared with experimental data obtained from lattice-matched InAlAs/InGaAs, InGaAsP/InP on InP substrate and AlGaAs/GaAs structures with rectangular wells and symmetric barriers, whose absorption peak wavelengths range from MWIR to VLWIR. The corresponding results are in a good agreement with experimental data at different temperatures and at a wide range of applied electric field.

  1. Characterization technique for inhomogeneous 4H-SiC Schottky contacts: A practical model for high temperature behavior

    Science.gov (United States)

    Brezeanu, G.; Pristavu, G.; Draghici, F.; Badila, M.; Pascu, R.

    2017-08-01

    In this paper, a characterization technique for 4H-SiC Schottky diodes with varying levels of metal-semiconductor contact inhomogeneity is proposed. A macro-model, suitable for high-temperature evaluation of SiC Schottky contacts, with discrete barrier height non-uniformity, is introduced in order to determine the temperature interval and bias domain where electrical behavior of the devices can be described by the thermionic emission theory (has a quasi-ideal performance). A minimal set of parameters, the effective barrier height and peff, the non-uniformity factor, is associated. Model-extracted parameters are discussed in comparison with literature-reported results based on existing inhomogeneity approaches, in terms of complexity and physical relevance. Special consideration was given to models based on a Gaussian distribution of barrier heights on the contact surface. The proposed methodology is validated by electrical characterization of nickel silicide Schottky contacts on silicon carbide (4H-SiC), where a discrete barrier distribution can be considered. The same method is applied to inhomogeneous Pt/4H-SiC contacts. The forward characteristics measured at different temperatures are accurately reproduced using this inhomogeneous barrier model. A quasi-ideal behavior is identified for intervals spanning 200 °C for all measured Schottky samples, with Ni and Pt contact metals. A predictable exponential current-voltage variation over at least 2 orders of magnitude is also proven, with a stable barrier height and effective area for temperatures up to 400 °C. This application-oriented characterization technique is confirmed by using model parameters to fit a SiC-Schottky high temperature sensor's response.

  2. High temperature structural sandwich panels

    Science.gov (United States)

    Papakonstantinou, Christos G.

    High strength composites are being used for making lightweight structural panels that are being employed in aerospace, naval and automotive structures. Recently, there is renewed interest in use of these panels. The major problem of most commercial available sandwich panels is the fire resistance. A recently developed inorganic matrix is investigated for use in cases where fire and high temperature resistance are necessary. The focus of this dissertation is the development of a fireproof composite structural system. Sandwich panels made with polysialate matrices have an excellent potential for use in applications where exposure to high temperatures or fire is a concern. Commercial available sandwich panels will soften and lose nearly all of their compressive strength temperatures lower than 400°C. This dissertation consists of the state of the art, the experimental investigation and the analytical modeling. The state of the art covers the performance of existing high temperature composites, sandwich panels and reinforced concrete beams strengthened with Fiber Reinforced Polymers (FRP). The experimental part consists of four major components: (i) Development of a fireproof syntactic foam with maximum specific strength, (ii) Development of a lightweight syntactic foam based on polystyrene spheres, (iii) Development of the composite system for the skins. The variables are the skin thickness, modulus of elasticity of skin and high temperature resistance, and (iv) Experimental evaluation of the flexural behavior of sandwich panels. Analytical modeling consists of a model for the flexural behavior of lightweight sandwich panels, and a model for deflection calculations of reinforced concrete beams strengthened with FRP subjected to fatigue loading. The experimental and analytical results show that sandwich panels made with polysialate matrices and ceramic spheres do not lose their load bearing capability during severe fire exposure, where temperatures reach several

  3. A model for life predictions of nickel-base superalloys in high-temperature low cycle fatigue

    Science.gov (United States)

    Romanoski, Glenn R.; Pelloux, Regis M.; Antolovich, Stephen D.

    1988-01-01

    Extensive characterization of low-cycle fatigue damage mechanisms was performed on polycrystalline Rene 80 and IN100 tested in the temperature range from 871 to 1000 C. Low-cycle fatigue life was found to be dominated by propagation of microcracks to a critical size governed by the maximum tensile stress. A model was developed which incorporates a threshold stress for crack extension, a stress-based crack growth expression, and a failure criterion. The mathematical equivalence between this mechanistically based model and the strain-life low-cycle fatigue law was demonstrated using cyclic stress-strain relationships. The model was shown to correlate the high-temperature low-cycle fatigue data of the different nickel-base superalloys considered in this study.

  4. Impedance model of lithium ion polymer battery considering temperature effects based on electrochemical principle: Part I for high frequency

    Science.gov (United States)

    Xiao, Meng; Choe, Song-Yul

    2015-03-01

    Measurement of impedance is one of well-known methods to experimentally characterize electrochemical properties of Li-ion batteries. The measured impedance responses are generally fitted to an equivalent circuit model that is composed of linear and nonlinear electric components that mimic behaviors of different layers of a battery. However, the parameters do not provide quantitative statements on charge dynamics considering material properties. Therefore, electrochemical models are widely employed to study the charge dynamics, but have not included high frequency responses predominantly determined by double layers. Thus, we have developed models for the double layer and bulk that are integrated into the electrochemical model for a pouch type Li-ion battery. The integrated model is validated against the frequency response obtained from EIS equipment at different temperatures as well as the time response. The results show that the proposed model is capable of representing the responses at charging and discharging in time and frequency domain.

  5. High-Temperature Deformation Constitutive Law for Dissimilar Weld Residual Stress Modeling: Effect of Thermal Load on Strain Hardening

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Xinghua [ORNL; Wang, Yanli [ORNL; Crooker, Paul [Electric Power Research Institute (EPRI); Feng, Zhili [ORNL

    2015-01-01

    Weld residual stress is one of the primary driving forces for primary water stress corrosion cracking in dissimilar metal welds (DMWs). To mitigate tensile residual stress in DMWs, it is critical to understand residual stress distribution by modeling techniques. Recent studies have shown that weld residual stress prediction using today s DMW residual stress models strongly depends on the strain-hardening constitutive model chosen. The commonly used strain-hardening models (isotropic, kinematic, and mixed) are all time-independent and inadequate to account for the time-dependent (viscous) plastic deformation at the elevated temperatures experienced during welding. For materials with profound strain-hardening, such as stainless steels and nickel-based alloys that are widely used in nuclear reactor and piping systems, the equivalent plastic strain the determinate factor of the flow stress can be highly dependent on the recovery and recrystallization processes. These processes are in turn a strong function of temperature, time, and deformation rate. Recently, the authors proposed a new temperature- and time-dependent strain-hardening constitutive model: the dynamic strain-hardening constitutive model. The application of such a model has resulted in improved weld residual stress prediction compared to the residual stress measurement results from the contour and deep-hole drilling methods. In this study, the dynamic strain-hardening behavior of Type 304 stainless steel and Alloy 82 used in pressure vessel nozzle DMWs is experimentally determined. The kinetics of the recovery and recrystallization of flow stress are derived from experiments, resulting in a semi-empirical equation as a function of pre-strain, time, and temperature that can be used for weld residual stress modeling. The method used in this work also provides an approach to study the kinetics of recovery and recrystallization of other materials with significant strain-hardening.

  6. Modeling of Thermal and Mechanical Behavior of ZrB2-SiC Ceramics after High Temperature Oxidation

    Directory of Open Access Journals (Sweden)

    Jun Wei

    2014-01-01

    Full Text Available The effects of oxidation on heat transfer and mechanical behavior of ZrB2-SiC ceramics at high temperature are modeled using a micromechanics based finite element model. The model recognizes that when exposed to high temperature in air ZrB2-SiC oxidizes into ZrO2, SiO2, and SiC-depleted ZrB2 layer. A steady-state heat transfer analysis was conducted at first and that is followed by a thermal stress analysis. A “global-local modeling” technique is used combining finite element with infinite element for thermal stress analysis. A theoretical formulation is developed for calculating the thermal conductivity of liquid phase SiO2. All other temperature dependent thermal and mechanical properties were obtained from published literature. Thermal stress concentrations occur near the pore due to the geometric discontinuity and material properties mismatch between the ceramic matrix and the new products. The predicted results indicate the development of thermal stresses in the SiO2 and ZrO2 layers and high residual stresses in the SiC-depleted ZrB2 layer.

  7. HIGH TEMPERATURE VACUUM MIXER

    Directory of Open Access Journals (Sweden)

    E. D. Chertov

    2015-01-01

    Full Text Available The work is devoted to the creation of a new type of mixer to produce homogeneous mixtures of dissimilar materials applied to recycling of housing and communal services waste. The article describes the design of a dual-chamber device of the original high-temperature vacuum mixer, there investigated the processes occurring in the chambers of such devices. The results of theoretical and experimental research of the process of mixing recycled polyethylene with a mixture of "grinded food waste – Eco wool” are presented. The problem of the optimum choice of bending the curvilinear blades in the working volume of the seal, which is achieved by setting their profile in the form of involute arc of several circles of different radii, is examined . The dependences, allowing to define the limits of the changes of the main mode parameters the angular velocity of rotation of the working body of the mixer using two ways of setting the profile of the curvilinear blade mixer are obtained. Represented design of the mixer is proposed to use for a wide range of tasks associated with the mixing of the components with a strongly pronounced difference of physic al chemical properties and, in particular, in the production of composites out of housing and communal services waste.

  8. Bilinear slack span calculation model. Slack span calculations for high-temperature cables; Bilineares Berechnungsmodell fuer Durchhangberechnungen. Durchhangberechnungen bei Hochtemperaturleitern

    Energy Technology Data Exchange (ETDEWEB)

    Scheel, Joerg; Dib, Ramzi [Fachhochschule Giessen-Friedberg, Friedberg (Germany); Sassmannshausen, Achim [DB Energie GmbH, Frankfurt (Main) (Germany). Arbeitsgebiet Bahnstromleitungen Energieerzeugungs- und Uebertragungssysteme; Riedl, Markus [Eon Netz GmbH, Bayreuth (Germany). Systemtechnik Leitungen

    2010-12-13

    Increasingly, high-temperature cables are used in high-voltage grids. Beyond a given temperature level, their slack span cannot be calculated accurately by conventional simple linear methods. The contribution investigates the behaviour of composite cables at high operating temperatures and its influence on the slack span and presents a more accurate, bilingual calculation method. (orig.)

  9. Estimating Important Electrode Parameters of High Temperature PEM Fuel Cells By Fitting a Model to Polarisation Curves and Impedance Spectra

    DEFF Research Database (Denmark)

    Vang, Jakob Rabjerg; Zhou, Fan; Andreasen, Søren Juhl;

    2015-01-01

    A high temperature PEM (HTPEM) fuel cell model capable of simulating both steady state and dynamic operation is presented. The purpose is to enable extraction of unknown parameters from sets of impedance spectra and polarisation curves. The model is fitted to two polarisation curves and four...... impedance spectra measured on a Dapozol 77 MEA. The model is capable of achieving good agreement with the recorded curves. Except at OCV, where the voltage is overpredicted, the simulated polarisation curves deviate maximum 3.0% from the measurements. The impedance spectra deviate maximum 3.7%. The fitted...... parameter values are within the range reported in literature. The only exception is the catalyst layer acid content, which is an order of magnitude lower. This may derive from acid migration. The model is used to illustrate the effect of reactant dynamics on the impedance spectrum. The model can aid...

  10. Constitutive Modeling of High-Temperature Flow Behavior of an Nb Micro-alloyed Hot Stamping Steel

    Science.gov (United States)

    Zhang, Shiqi; Feng, Ding; Huang, Yunhua; Wei, Shizhong; Mohrbacher, Hardy; Zhang, Yue

    2016-03-01

    The thermal deformation behavior and constitutive models of an Nb micro-alloyed 22MnB5 steel were investigated by conducting isothermal uniaxial tensile tests at the temperature range of 873-1223 K with strain rates of 0.1-10 s-1. The results indicated that the investigated steel showed typical work hardening and dynamic recovery behavior during hot deformation, and the flow stress decreased with a decrease in strain rate and/or an increase in temperature. On the basis of the experimental data, the modified Johnson-Cook (modified JC), modified Norton-Hoff (modified NH), and Arrhenius-type (AT) constitutive models were established for the subject steel. However, the flow stress values predicted by these three models revealed some remarkable deviations from the experimental values for certain experimental conditions. Therefore, a new combined modified Norton-Hoff and Arrhenius-type constitutive model (combined modified NH-AT model), which accurately reflected both the work hardening and dynamic recovery behavior of the subject steel, was developed by introducing the modified parameter k ɛ. Furthermore, the accuracy of these constitutive models was assessed by the correlation coefficient, the average absolute relative error, and the root mean square error, which indicated that the flow stress values computed by the combined modified NH-AT model were highly consistent with the experimental values (R = 0.998, AARE = 1.63%, RMSE = 3.85 MPa). The result confirmed that the combined modified NH-AT model was suitable for the studied Nb micro-alloyed hot stamping steel. Additionally, the practicability of the new model was also verified using finite element simulations in ANSYS/LS-DYNA, and the results confirmed that the new model was practical and highly accurate.

  11. Advances in high temperature chemistry

    CERN Document Server

    Eyring, Leroy

    1969-01-01

    Advances in High Temperature Chemistry, Volume 2 covers the advances in the knowledge of the high temperature behavior of materials and the complex and unfamiliar characteristics of matter at high temperature. The book discusses the dissociation energies and free energy functions of gaseous monoxides; the matrix-isolation technique applied to high temperature molecules; and the main features, the techniques for the production, detection, and diagnosis, and the applications of molecular beams in high temperatures. The text also describes the chemical research in streaming thermal plasmas, as w

  12. Ultra-High Temperature Gratings

    Institute of Scientific and Technical Information of China (English)

    John Canning; Somnath Bandyopadhyay; Michael Stevenson; Kevin Cook

    2008-01-01

    Regenerated gratings seeded by type-Ⅰ gratings are shown to withstand temperatures beyond 1000 ℃. The method of regeneration offers a new approach to increasing temperature resistance of stable fibre Bragg and other gratings. These ultra-high temperature (UHT) gratings extend the applicability of silicate based components to high temperature applications such as monitoring of smelters and vehicle and aircraft engines to high power fibre lasers.

  13. High temperature solid oxide fuel cell integrated with novel allothermal biomass gasification. Part I: Modelling and feasibility study

    Science.gov (United States)

    Panopoulos, K. D.; Fryda, L. E.; Karl, J.; Poulou, S.; Kakaras, E.

    Biomass gasification derived fuel gas is a renewable fuel that can be used by high temperature fuel cells. In this two-part work an attempt is made to investigate the integration of a near atmospheric pressure solid oxide fuel cell (SOFC) with a novel allothermal biomass steam gasification process into a combined heat and power (CHP) system of less than MW e nominal output range. Heat for steam gasification is supplied from SOFC depleted fuel into a fluidised bed combustor via high temperature sodium heat pipes. The integrated system model was built in Aspen Plus™ simulation software and is described in detail. Part I investigates the feasibility and critical aspects of the system based on modelling results. A low gasification steam to biomass ratio (STBR = 0.6) is used to avoid excess heat demands and to allow effective H 2S high temperature removal. Water vapour is added prior to the anode to avoid carbon deposition. The SOFC off gases adequately provide gasification heat when fuel utilisation factors are f = 0.7 and current density 2500 A m -2 the electrical efficiency is estimated at 36% while thermal efficiency at 14%. An exergy analysis is presented in Part II.

  14. High-Temperature Piezoelectric Sensing

    Directory of Open Access Journals (Sweden)

    Xiaoning Jiang

    2013-12-01

    Full Text Available Piezoelectric sensing is of increasing interest for high-temperature applications in aerospace, automotive, power plants and material processing due to its low cost, compact sensor size and simple signal conditioning, in comparison with other high-temperature sensing techniques. This paper presented an overview of high-temperature piezoelectric sensing techniques. Firstly, different types of high-temperature piezoelectric single crystals, electrode materials, and their pros and cons are discussed. Secondly, recent work on high-temperature piezoelectric sensors including accelerometer, surface acoustic wave sensor, ultrasound transducer, acoustic emission sensor, gas sensor, and pressure sensor for temperatures up to 1,250 °C were reviewed. Finally, discussions of existing challenges and future work for high-temperature piezoelectric sensing are presented.

  15. A mathematical model of the formation of fermentable sugars from starch hydrolysis during high-temperature mashing.

    Science.gov (United States)

    Muller

    2000-08-01

    During the mashing process of brewing, activity of the amylolytic enzymes decays due to the high temperatures used to gelatinise the starch. Because the different enzymes produce different sugars, high temperatures can be exploited to modify the fermentability of resulting worts. This is especially useful when producing low alcohol beers. The expression a.exp(b.t)-c.exp(d.t) (where t is the temperature of the mash in degrees C) provides a simple but useful description of the activity of the amylases. Combining the activities of alpha- and beta-amylases results in a prediction of the resulting fermentability. A simple modification to the expression accommodates changes in mash thickness. The error of prediction is approximately 3 degrees of fermentability. The model is not appropriate for predicting the fermentability of worts produced at the lower standard mashing temperatures. It can be used without the necessity of analytical parameters so analyses that the brewer would not normally perform are not required. If increased accuracy is needed, the results of two previous mashes can be used to modify the parameters used.

  16. High temperature superconductor accelerator magnets

    NARCIS (Netherlands)

    van Nugteren, J.

    2016-01-01

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding 20T. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and dev

  17. 2D numerical modelling of gas temperature in a nanosecond pulsed longitudinal He-SrBr2 discharge excited in a high temperature gas-discharge tube for the high-power strontium laser

    Science.gov (United States)

    Chernogorova, T. P.; Temelkov, K. A.; Koleva, N. K.; Vuchkov, N. K.

    2016-05-01

    An active volume scaling in bore and length of a Sr atom laser excited in a nanosecond pulse longitudinal He-SrBr2 discharge is carried out. Considering axial symmetry and uniform power input, a 2D model (r, z) is developed by numerical methods for determination of gas temperature in a new large-volume high-temperature discharge tube with additional incompact ZrO2 insulation in the discharge free zone, in order to find out the optimal thermal mode for achievement of maximal output laser parameters. A 2D model (r, z) of gas temperature is developed by numerical methods for axial symmetry and uniform power input. The model determines gas temperature of nanosecond pulsed longitudinal discharge in helium with small additives of strontium and bromine.

  18. On the high-temperature combustion of n-butanol: Shock tube data and an improved kinetic model

    KAUST Repository

    Vasu, Subith S.

    2013-11-21

    The combustion of n-butanol has received significant interest in recent years, because of its potential use in transportation applications. Researchers have extensively studied its combustion chemistry, using both experimental and theoretical methods; however, additional work is needed under specific conditions to improve our understanding of n-butanol combustion. In this study, we report new OH time-history data during the high-temperature oxidation of n-butanol behind reflected shock waves over the temperature range of 1300-1550 K and at pressures near 2 atm. These data were obtained at Stanford University, using narrow-line-width ring dye laser absorption of the R1(5) line of OH near 306.7 nm. Measured OH time histories were modeled using comprehensive n-butanol literature mechanisms. It was found that n-butanol unimolecular decomposition rate constants commonly used in chemical kinetic models, as well as those determined from theoretical studies, are unable to predict the data presented herein. Therefore, an improved high-temperature mechanism is presented here, which incorporates recently reported rate constants measured in a single pulse shock tube [C. M. Rosado-Reyes and W. Tsang, J. Phys. Chem. A 2012, 116, 9825-9831]. Discussions are presented on the validity of the proposed mechanism against other literature shock tube experiments. © 2013 American Chemical Society.

  19. Classical O(N) Heisenberg model: Extended high-temperature series for two, three, and four dimensions

    Science.gov (United States)

    Butera, P.; Comi, M.; Marchesini, G.

    1990-06-01

    We present simple tables of integers from which it is possible to reconstruct the high-temperature series coefficients through β14 for the susceptibility, for the second correlation moment, and for the second field derivative of the susceptibility of the O(N) classical Heisenberg model on a simple (hyper)cubic lattice in dimension d=2, 3, and 4 and for any N. To construct the tables we have used the recent extension of the high-temperature series by M. Luscher and P. Weisz and some analytic properties in N that we have derived from the Schwinger-Dyson equations of the O(N) model. We also present a numerical study of these series in the d=2 case. The main results are: (a) the extended series give further support to the Cardy-Hamber-Nienhuis exact formulas for the critical exponents when -2=3 there are no indications of any critical point at finite β (c) the series are consistent with the low-temperature asymptotic forms predicted by the perturbative renormalization group.

  20. Experiment and Modeling of Simultaneous Creep, Plasticity and Transformation of High Temperature Shape Memory Alloys During Cyclic Actuation

    Science.gov (United States)

    Kumar, Parikshith K.; Desai, Uri; Chatzigeorgiou, George; Lagoudas, Dimitris C.; Monroe, James; Karaman, Ibrahim; Noebe, Ron; Bigelow, Glen

    2010-01-01

    The present work is focused on studying the cycling actuation behavior of HTSMAs undergoing simultaneous creep and transformation. For the thermomechanical testing, a high temperature test setup was assembled on a MTS frame with the capability to test up to temperatures of 600 C. Constant stress thermal cycling tests were conducted to establish the actuation characteristics and the phase diagram for the chosen HTSMA. Additionally, creep tests were conducted at constant stress levels at different test temperatures to characterize the creep behavior of the alloy over the operational range. A thermodynamic constitutive model is developed and extended to take into account a) the effect of multiple thermal cycling on the generation of plastic strains due to transformation (TRIP strains) and b) both primary and secondary creep effects. The model calibration is based on the test results. The creep tests and the uniaxial tests are used to identify the viscoplastic behavior of the material. The parameters for the SMA properties, regarding the transformation and transformation induced plastic strain evolutions, are obtained from the material phase diagram and the thermomechanical tests. The model is validated by predicting the material behavior at different thermomechanical test conditions.

  1. van Hove singularities and tight-binding model in high-temperature superconductor H3Se

    Science.gov (United States)

    Cui, Huijuan; Li, Menglei; Zheng, Fawei; Zhang, Ping

    2017-08-01

    Ever since high-Tc superconductivity was found in H3S at 203 K under 200 GPa pressure, researches on hydrogen-rich family including H3S, H3P, and H3Te have been intensively carried out. Among those compounds, H3Se is a promising candidate of the same space group with H3S. In this work, we have thoroughly studied the electronic and phonon structures of H3Se using density functional theory (DFT) calculations. It is demonstrated that the electronic bands of H3Se contain van Hove singularities near the Fermi energy, which play a significant role in the superconductivity of this material. Besides, an accurate tight-binding model is proposed based on the Wannier function interpolations which can capture the main features of the electronic structures of H3Se. Moreover, we have also discussed the phonon dispersions and vibration modes for a better understanding of the phonon-electron interaction in H3Se.

  2. High temperature catalytic membrane reactors

    Energy Technology Data Exchange (ETDEWEB)

    1990-03-01

    Current state-of-the-art inorganic oxide membranes offer the potential of being modified to yield catalytic properties. The resulting modules may be configured to simultaneously induce catalytic reactions with product concentration and separation in a single processing step. Processes utilizing such catalytically active membrane reactors have the potential for dramatically increasing yield reactions which are currently limited by either thermodynamic equilibria, product inhibition, or kinetic selectivity. Examples of commercial interest include hydrogenation, dehydrogenation, partial and selective oxidation, hydrations, hydrocarbon cracking, olefin metathesis, hydroformylation, and olefin polymerization. A large portion of the most significant reactions fall into the category of high temperature, gas phase chemical and petrochemical processes. Microporous oxide membranes are well suited for these applications. A program is proposed to investigate selected model reactions of commercial interest (i.e. dehydrogenation of ethylbenzene to styrene and dehydrogenation of butane to butadiene) using a high temperature catalytic membrane reactor. Membranes will be developed, reaction dynamics characterized, and production processes developed, culminating in laboratory-scale demonstration of technical and economic feasibility. As a result, the anticipated increased yield per reactor pass economic incentives are envisioned. First, a large decrease in the temperature required to obtain high yield should be possible because of the reduced driving force requirement. Significantly higher conversion per pass implies a reduced recycle ratio, as well as reduced reactor size. Both factors result in reduced capital costs, as well as savings in cost of reactants and energy.

  3. Characterisation and Modelling of a High Temperature PEM Fuel Cell Stack using Electrochemical Impedance Spectroscopy

    DEFF Research Database (Denmark)

    Andreasen, Søren Juhl; Jespersen, Jesper Lebæk; Schaltz, Erik

    2009-01-01

    temperature PEM (HTPEM) fuel cell stack. A Labview virtual instrument has been developed to perform the signal generation and data acquisition which is needed to perform EIS. The typical output of an EIS measurement on a fuel cell, is a Nyquist plot, which shows the imaginary and real part of the impedance...

  4. Modeling and simulation of high-temperature polymer electrolyte fuel cells; Modellierung und Simulation von Hochtemperatur-Polymerelektrolyt-Brennstoffzellen

    Energy Technology Data Exchange (ETDEWEB)

    Kvesic, Mirko

    2012-07-01

    Fuel cells are electrochemical energy converters that convert chemical energy of constantly fed reactants directly into electricity. The most commonly used fuel gas in this respect is hydrogen, which is either produced in pure form by electrolysis, for example, or as a hydrogen-rich gas mixture (reformate gas), produced by reforming diesel or kerosene e.g. However, a disadvantage of reformate gas is that it contains additional carbon monoxide (CO), which leads to catalyst poisoning in the fuel cell. Since higher operating temperatures also lead to a higher CO tolerance, the use of high-temperature Polymer-Electrolyte-Fuel-Cells (HT-PEFCs) is particularly suitable for reformate operation. The aim of the presented work is the modeling and CFD-simulation of HT-PEFC stacks with the intention of gaining a better understanding of multi-physical processes in the stack operation as well as the optimization and analysis of existing stack designs. The geometric modeling used is based on the Porous Volume Model, which significantly reduces the required number of computing elements. Furthermore, the electrochemical models for hydrogen / air and reformate / air operation, which were taking the CO poisoning effects into account, are developed in this work and implemented in the software ANSYS / Fluent. The resulting simulations indicated the optimal flow configuration for the stack operation in terms of the homogeneous current density distribution, which has a positive effect on the stack aging. Thus, the current densities showed a strong homogeneity regarding the stack configuration anode / cathode in counter-flow and anode / cooling in co-flow. The influence of cooling strategies was examined for the stack performance in a similar way. In the following, the local temperature distribution as well as temperature peaks within the stack could be predicted and validated with experimental measurements. Further on, the model scalability and thus the general validity of the developed

  5. The oscillatory behavior of the high-temperature expansion of Dyson's hierarchical model: A renormalization group analysis

    Science.gov (United States)

    Meurice, Y.; Niermann, S.; Ordaz, G.

    1997-04-01

    We calculate 800 coefficients of the high-temperature expansion of the magnetic susceptibility of Dyson's hierarchical model with a Landau-Ginzburg measure. Log-periodic corrections to the scaling laws appear as in the case of an Ising measure. The period of oscillation appears to be a universal quantity given in good approximation by the logarithm of the largest eigenvalue of the linearized RG transformation, in agreement with a possibility suggested by Wilson and developed by Niemeijer and van Leeuwen. We estimate γ to be 1.300 (with a systematic error of the order of 0.002), in good agreement with the results obtained with other methods, such as the ɛ-expansion. We briefly discuss the relationship between the oscillations and the zeros of the partition function near the critical point in the complex temperature plane.

  6. Luminescent Paints Used for Rotating Temperature and Pressure Measurements on Scale-Model High-Bypass-Ratio Fans

    Science.gov (United States)

    Bencic, Timothy J.

    1998-01-01

    NASA Lewis Research Center is a leader in the application of temperature- and pressuresensitive paints (TSP and PSP) in rotating environments. Tests were recently completed on several scale model, high-bypass-ratio turbofans in Lewis' 9- by 15-Foot Low-Speed Wind Tunnel. Two of the test objectives were to determine the aerodynamic and acoustic performance of the fan designs. Using TSP and PSP, researchers successfully achieved fullfield aerodynamic loading profiles. The visualized loading profiles may help researchers identify factors contributing to the fans' performance and to the acoustic characteristics associated with the flow physics on the surface of the blades.

  7. State of the art on high temperature thermal energy storage for power generation. Part 1. Concepts, materials and modellization

    Energy Technology Data Exchange (ETDEWEB)

    Gil, Antoni; Medrano, Marc; Martorell, Ingrid; Cabeza, Luisa F. [GREA Innovacio Concurrent, Universitat de Lleida, Pere de Cabrera s/n, 25001-Lleida (Spain); Lazaro, Ana; Dolado, Pablo; Zalba, Belen [Instituto de Investigacion en Ingenieria de Aragon, I3A, Grupo de Ingenieria Termica y Sistemas Energeticos (GITSE), Dpto. Ingenieria Mecanica, Area de Maquinas y Motores Termicos, Universidad de Zaragoza, Campus Politecnico Rio Ebro, Edificio ' Agustin de Betancourt' , Maria de Luna s/n, 50018 Zaragoza (Spain)

    2010-01-15

    Concentrated solar thermal power generation is becoming a very attractive renewable energy production system among all the different renewable options, as it has have a better potential for dispatchability. This dispatchability is inevitably linked with an efficient and cost-effective thermal storage system. Thus, of all components, thermal storage is a key one. However, it is also one of the less developed. Only a few plants in the world have tested high temperature thermal energy storage systems. In this paper, the different storage concepts are reviewed and classified. All materials considered in literature or plants are listed. And finally, modellization of such systems is reviewed. (author)

  8. High temperature materials; Materiaux a hautes temperatures

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2003-07-01

    The aim of this workshop is to share the needs of high temperature and nuclear fuel materials for future nuclear systems, to take stock of the status of researches in this domain and to propose some cooperation works between the different research organisations. The future nuclear systems are the very high temperature (850 to 1200 deg. C) gas cooled reactors (GCR) and the molten salt reactors (MSR). These systems include not only the reactor but also the fabrication and reprocessing of the spent fuel. This document brings together the transparencies of 13 communications among the 25 given at the workshop: 1) characteristics and needs of future systems: specifications, materials and fuel needs for fast spectrum GCR and very high temperature GCR; 2) high temperature materials out of neutron flux: thermal barriers: materials, resistance, lifetimes; nickel-base metal alloys: status of knowledge, mechanical behaviour, possible applications; corrosion linked with the gas coolant: knowledge and problems to be solved; super-alloys for turbines: alloys for blades and discs; corrosion linked with MSR: knowledge and problems to be solved; 3) materials for reactor core structure: nuclear graphite and carbon; fuel assembly structure materials of the GCR with fast neutron spectrum: status of knowledge and ceramics and cermets needs; silicon carbide as fuel confinement material, study of irradiation induced defects; migration of fission products, I and Cs in SiC; 4) materials for hydrogen production: status of the knowledge and needs for the thermochemical cycle; 5) technologies: GCR components and the associated material needs: compact exchangers, pumps, turbines; MSR components: valves, exchangers, pumps. (J.S.)

  9. PREFACE: Special section featuring selected papers from the 3rd International Workshop on Numerical Modelling of High Temperature Superconductors Special section featuring selected papers from the 3rd International Workshop on Numerical Modelling of High Temperature Superconductors

    Science.gov (United States)

    Granados, Xavier; Sánchez, Àlvar; López-López, Josep

    2012-10-01

    The development of superconducting applications and superconducting engineering requires the support of consistent tools which can provide models for obtaining a good understanding of the behaviour of the systems and predict novel features. These models aim to compute the behaviour of the superconducting systems, design superconducting devices and systems, and understand and test the behavior of the superconducting parts. 50 years ago, in 1962, Charles Bean provided the superconducting community with a model efficient enough to allow the computation of the response of a superconductor to external magnetic fields and currents flowing through in an understandable way: the so called critical-state model. Since then, in addition to the pioneering critical-state approach, other tools have been devised for designing operative superconducting systems, allowing integration of the superconducting design in nearly standard electromagnetic computer-aided design systems by modelling the superconducting parts with consideration of time-dependent processes. In April 2012, Barcelona hosted the 3rd International Workshop on Numerical Modelling of High Temperature Superconductors (HTS), the third in a series of workshops started in Lausanne in 2010 and followed by Cambridge in 2011. The workshop reflected the state-of-the-art and the new initiatives of HTS modelling, considering mathematical, physical and technological aspects within a wide and interdisciplinary scope. Superconductor Science and Technology is now publishing a selection of papers from the workshop which have been selected for their high quality. The selection comprises seven papers covering mathematical, physical and technological topics which contribute to an improvement in the development of procedures, understanding of phenomena and development of applications. We hope that they provide a perspective on the relevance and growth that the modelling of HTS superconductors has achieved in the past 25 years.

  10. High Temperature Superconductor Machine Prototype

    DEFF Research Database (Denmark)

    Mijatovic, Nenad; Jensen, Bogi Bech; Træholt, Chresten

    2011-01-01

    A versatile testing platform for a High Temperature Superconductor (HTS) machine has been constructed. The stationary HTS field winding can carry up to 10 coils and it is operated at a temperature of 77K. The rotating armature is at room temperature. Test results and performance for the HTS field...

  11. High-order scheme for the source-sink term in a one-dimensional water temperature model

    Science.gov (United States)

    Jing, Zheng; Kang, Ling

    2017-01-01

    The source-sink term in water temperature models represents the net heat absorbed or released by a water system. This term is very important because it accounts for solar radiation that can significantly affect water temperature, especially in lakes. However, existing numerical methods for discretizing the source-sink term are very simplistic, causing significant deviations between simulation results and measured data. To address this problem, we present a numerical method specific to the source-sink term. A vertical one-dimensional heat conduction equation was chosen to describe water temperature changes. A two-step operator-splitting method was adopted as the numerical solution. In the first step, using the undetermined coefficient method, a high-order scheme was adopted for discretizing the source-sink term. In the second step, the diffusion term was discretized using the Crank-Nicolson scheme. The effectiveness and capability of the numerical method was assessed by performing numerical tests. Then, the proposed numerical method was applied to a simulation of Guozheng Lake (located in central China). The modeling results were in an excellent agreement with measured data. PMID:28264005

  12. Zirconium-cerin solid solutions: thermodynamic model and thermal stability at high temperature; Solutions solides de zirconium dans la cerine: modele thermodynamique et stabilite thermique a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Janvier, C.

    1998-04-02

    The oxides-gaseous dioxygen equilibria and the textural thermal stability of six zirconium-cerin solutions Ce{sub 1-x}Zr{sub x}O{sub 2} (0model where the point defects of solutions are included describe them the best. It becomes then possible to know the variations of the concentrations of the point defects in terms of temperature, oxygen pressure and zirconium concentration. A kinetic study (by calcination at 950 degrees Celsius of the solid solutions) of the specific surface area decrease has revealed a minima (0

  13. A Creep Damage Model for High-Temperature Deformation and Failure of 9Cr-1Mo Steel Weldments

    Directory of Open Access Journals (Sweden)

    Mehdi Basirat

    2015-08-01

    Full Text Available A dislocation-based creep model combined with a continuum damage formulation was developed and implemented in the finite element method to simulate high temperature deformation behavior in modified 9Cr-1Mo steel welds. The evolution of dislocation structures was considered as the main driving mechanism for creep. The effect of void growth, precipitate coarsening, and solid solution depletion were considered to be the operating damage processes. A semi-implicit numerical integration scheme was developed and implemented in the commercial finite element code ABAQUS-Standard as a user material subroutine. Furthermore, several creep tests of modified 9Cr-1Mo steel welded specimens were conducted at temperatures between 550–700 °C and stresses between 80–200 MPa. The accuracy of the model was verified by comparing the finite element results with experiments. The comparison between the experimental and computational results showed excellent agreement. The model can be used to simulate and predict the creep-damage behavior of Cr-Mo steel components used as structural applications in power plants.

  14. High Temperature Electrostrictive Ceramics Project

    Data.gov (United States)

    National Aeronautics and Space Administration — TRS Technologies proposes to develop high temperature electrostrictors from bismuth-based ferroelectrics. These materials will exhibit high strain and low loss in...

  15. Predicting Microstructure Development During HighTemperature Nitriding of Martensitic Stainless SteelsUsing Thermodynamic Modeling

    Directory of Open Access Journals (Sweden)

    Tschiptschin André Paulo

    2002-01-01

    Full Text Available Thermodynamic calculations of the Fe-Cr-N System in the region of the Gas Phase Equilibria have been compared with experimental results of maximum nitrogen absorption during nitriding of two Martensitic Stainless Steels (a 6 mm thick sheet of AISI 410S steel and green powder compacts of AISI 434L steel under N2 atmospheres. The calculations have been performed combining the Fe-Cr-N System description contained in the SGTE Solid Solution Database and the gas phase for the N System contained in the SGTE Substances Database. Results show a rather good agreement for total nitrogen absorption in the steel and nitrogen solubility in austenite in the range of temperatures between 1273 K and 1473 K and in the range of pressures between 0.1 and 0.36 MPa. Calculations show that an appropriate choice of heat treatment parameters can lead to optimal nitrogen absorption in the alloy. It was observed in the calculations that an increased pressure stabilizes CrN at expenses of Cr2N - type nitrides.

  16. Reactive transport model of growth and methane production by high-temperature methanogens in hydrothermal regions of the subseafloor

    Science.gov (United States)

    Stewart, L. C.; Algar, C. K.; Topçuoğlu, B. D.; Fortunato, C. S.; Larson, B. I.; Proskurowski, G. K.; Butterfield, D. A.; Vallino, J. J.; Huber, J. A.; Holden, J. F.

    2014-12-01

    Hydrogenotrophic methanogens are keystone high-temperature autotrophs in deep-sea hydrothermal vents and tracers of habitability and biogeochemical activity in the hydrothermally active subseafloor. At Axial Seamount, nearly all thermophilic methanogens are Methanothermococcus and Methanocaldococcus species, making this site amenable to modeling through pure culture laboratory experiments coupled with field studies. Based on field microcosm incubations with 1.2 mM, 20 μM, or no hydrogen, the growth of methanogens at 55°C and 80°C is limited primarily by temperature and hydrogen availability, with ammonium amendment showing no consistent effect on total methane output. The Arrhenius constants for methane production by Methanocaldococcus jannaschii (optimum 82°C) and Methanothermococcus thermolithotrophicus (optimum 65°C) were determined in pure culture bottle experiments. The Monod constants for hydrogen concentration were measured by growing both organisms in a 2-liter chemostat at two dilution rates; 55°C, 65°C and 82°C; and variable hydrogen concentrations. M. jannaschii showed higher ks and Vmax constants than M. thermolithotrophicus. In the field, hydrogen and methane concentrations in hydrothermal end-member and low-temperature diffuse fluids were measured, and the concentrations of methanogens that grow at 55°C and 80°C in diffuse fluids were determined using most-probable-number estimates. Methane concentration anomalies in diffuse fluids relative to end-member hydrothermal concentrations and methanogen cell concentrations are being used to constrain a 1-D reactive transport model using the laboratory-determined Arrhenius and Monod constants for methane production by these organisms. By varying flow path length and subseafloor cell concentrations in the model, our goal is to determine solutions for the potential depth of the subseafloor biosphere coupled with the amount of methanogenic biomass it contains.

  17. Development of a High-Temperature Tensile Tester for Micromechanical Characterization of Materials Supporting Meso-Scale ICME Models

    Science.gov (United States)

    Alam, Zafir; Eastman, David; Jo, Minjea; Hemker, Kevin

    2016-11-01

    A high-temperature tensile tester (HTTT) has been established for the evaluation of micro-mechanical properties of materials at the meso-scale. Metals and ceramics can now be tested at temperatures and strain rates between room temperature and 1200°C and 10-5 s-1 to 10-1 s-1, respectively. The samples are heated in a compact clam shell furnace and strain is measured directly in the sample gage with digital image correlation. The HTTT extracts representative mechanical properties, as evidenced by the similarity in the evaluated micro-tensile properties of a solid solution-strengthened Ni-base superalloy Ni-625 with that of the bulk. The effectiveness of the HTTT has also been demonstrated in evaluating the tensile and stress relaxation/short-term creep properties of a polycrystalline Ni-base superalloy René 88DT. The versatility in carrying out tensile, short-term creep, bend tests, and fracture toughness measurements makes the HTTT a robust experimental tool for small-scale and scale-specific benchmarking of multi-scale ICME models.

  18. Testing and Modeling Ultra-High Temperature Ceramic (UHTC) Materials For Hypersonic Flight

    Science.gov (United States)

    2011-11-30

    conditions, exothermic oxidation reactions and endothermic evaporation/decomposition reactions have little impact on the heat balance at the surface, and the...radiometer, which in turn lies completely on the flat face of the sample away from the rounded edges. Tests were filmed with a high- definition ...difference between the hot boundary layer gases and the cooler specimen surface, while chemical heating results from exothermic reactions on the

  19. Numerical modeling of high-temperature deep wells in the Cerro Prieto geothermal field, Mexico

    OpenAIRE

    García, A.; F. Ascencio; Espinosa, G.; E. Santoyo; H. Gutiérrez; V. Arellano

    1999-01-01

    A numerical modeling study of three non-producing deep geothermal wells from Cerro Prieto is presented. We compute the expected production characteristics of these wells in order to determine if their inability to sustain flow was due to (i) heat loss effects in the well, (ii) the influence of production casing diameters, (iii) the transient heat loss during the first few days of well discharge, or (iv) the effect of secondary low-enthalpy inflows. A new version of the wellbore flow simulator...

  20. Sensitivity of high-temperature weather to initial soil moisture: a case study with the WRF model

    Science.gov (United States)

    Zeng, X.-M.; Wang, B.; Zhang, Y.; Song, S.; Huang, X.; Zheng, Y.; Chen, C.; Wang, G.

    2014-05-01

    Using the Weather Research and Forecasting model (WRF), we investigate the sensitivity of simulated short-range high-temperature weather to initial soil moisture for the East China extremely hot event in late July 2003 via a succession of 24 h simulations. The initial soil moisture (SMOIS) in the Noah land surface scheme is prescribed for five groups of designed simulations, i.e., relative to the control run (CTL), SMOIS is changed by -25, -50, +25 and +50% in the DRY25, DRY50, WET25 and WET50 groups, respectively, with ten 24 h-long integrations performed in each group. We focus on above-35 °C (standard of so-called "high-temperature" event in China) 2 m surface air temperature (SAT) at 06:00 UTC (roughly 12:00 LT in the study domain) to analyze the occurrence of the high-temperature event. Ten-day mean results show that the 06:00 UTC SAT (SAT06) is sensitive to the SMOIS change, i.e., SAT06 exhibits an apparent rising with the SMOIS decrease (e.g., compared with CTL, DRY25 results in a 1 °C SAT06 rising in general over land surface of East China), areas with above-35 °C SAT06 are most affected, and the simulations are found to be more sensitive to the SMOIS decrease than to the SMOIS increase, suggesting that hot weather can be amplified under low soil moisture conditions. With regard to the mechanism of influencing the extreme high SAT06, sensible heat flux shows to directly heat the lower atmosphere, latent heat flux is found to be more sensitive to the SMOIS change and results in the overall increase of surface net radiation due to the increased greenhouse effect (e.g., with the SMOIS increase of 25% from DRY25 to CTL, the ten-day mean net radiation is increased by 5 W m-2), and a negative (positive) feedback is found between regional atmospheric circulation and air temperature in the lower atmosphere (mid-troposphere) due to the unique dynamic nature of the western Pacific subtropical high. Using a method based on an analogous temperature relationship, a

  1. Status on the Component Models Developed in the Modelica Framework: High-Temperature Steam Electrolysis Plant & Gas Turbine Power Plant

    Energy Technology Data Exchange (ETDEWEB)

    Suk Kim, Jong [Idaho National Lab. (INL), Idaho Falls, ID (United States); McKellar, Michael [Idaho National Lab. (INL), Idaho Falls, ID (United States); Bragg-Sitton, Shannon M. [Idaho National Lab. (INL), Idaho Falls, ID (United States); Boardman, Richard D. [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2016-10-01

    This report has been prepared as part of an effort to design and build a modeling and simulation (M&S) framework to assess the economic viability of a nuclear-renewable hybrid energy system (N-R HES). In order to facilitate dynamic M&S of such an integrated system, research groups in multiple national laboratories have been developing various subsystems as dynamic physics-based components using the Modelica programming language. In fiscal year (FY) 2015, Idaho National Laboratory (INL) performed a dynamic analysis of two region-specific N-R HES configurations, including the gas-to-liquid (natural gas to Fischer-Tropsch synthetic fuel) and brackish water reverse osmosis desalination plants as industrial processes. In FY 2016, INL has developed two additional subsystems in the Modelica framework: a high-temperature steam electrolysis (HTSE) plant and a gas turbine power plant (GTPP). HTSE has been proposed as a high priority industrial process to be integrated with a light water reactor (LWR) in an N-R HES. This integrated energy system would be capable of dynamically apportioning thermal and electrical energy (1) to provide responsive generation to the power grid and (2) to produce alternative industrial products (i.e., hydrogen and oxygen) without generating any greenhouse gases. A dynamic performance analysis of the LWR/HTSE integration case was carried out to evaluate the technical feasibility (load-following capability) and safety of such a system operating under highly variable conditions requiring flexible output. To support the dynamic analysis, the detailed dynamic model and control design of the HTSE process, which employs solid oxide electrolysis cells, have been developed to predict the process behavior over a large range of operating conditions. As first-generation N-R HES technology will be based on LWRs, which provide thermal energy at a relatively low temperature, complementary temperature-boosting technology was suggested for integration with the

  2. High Temperature Superconductor Accelerator Magnets

    CERN Document Server

    AUTHOR|(CDS)2079328; de Rijk, Gijs; Dhalle, Marc

    2016-11-10

    For future particle accelerators bending dipoles are considered with magnetic fields exceeding $20T$. This can only be achieved using high temperature superconductors (HTS). These exhibit different properties from classical low temperature superconductors and still require significant research and development before they can be applied in a practical accelerator magnet. In order to study HTS in detail, a five tesla demonstrator magnet named Feather-M2 is designed and constructed. The magnet is based on ReBCO coated conductor, which is assembled into a $10kA$ class Roebel cable. A new and optimized Aligned Block layout is used, which takes advantage of the anisotropy of the conductor. This is achieved by providing local alignment of the Roebel cable in the coil windings with the magnetic field lines. A new Network Model capable of analyzing transient electro-magnetic and thermal phenomena in coated conductor cables and coils is developed. This model is necessary to solve critical issues in coated conductor ac...

  3. Demonstrating the Model Nature of the High-Temperature Superconductor HgBa2CuO4+d

    Energy Technology Data Exchange (ETDEWEB)

    Barisic, Neven; Li, Yuan; Zhao, Xudong; Cho, Yong-Chan; Chabot-Couture, Guillaume; Yu, Guichuan; Greven, Martin; /SLAC, SSRL /Boskovic Inst., Zagreb /Stanford U., Phys. Dept. /Jilin U. /Stanford U., Appl. Phys. Dept.

    2008-09-30

    The compound HgBa{sub 2}CuO{sub 4+{delta}} (Hg1201) exhibits a simple tetragonal crystal structure and the highest superconducting transition temperature (T{sub c}) among all single Cu-O layer cuprates, with T{sub c} = 97 K (onset) at optimal doping. Due to a lack of sizable single crystals, experimental work on this very attractive system has been significantly limited. Thanks to a recent breakthrough in crystal growth, such crystals have now become available. Here, we demonstrate that it is possible to identify suitable heat treatment conditions to systematically and uniformly tune the hole concentration of Hg1201 crystals over a wide range, from very underdoped (T{sub c} = 47 K, hole concentration p {approx} 0.08) to overdoped (T{sub c} = 64 K, p {approx} 0.22). We then present quantitative magnetic susceptibility and DC charge transport results that reveal the very high-quality nature of the studied crystals. Using XPS on cleaved samples, we furthermore demonstrate that it is possible to obtain large surfaces of good quality. These characterization measurements demonstrate that Hg1201 should be viewed as a model high-temperature superconductor, and they provide the foundation for extensive future experimental work.

  4. Temperature- and voltage-dependent trap generation model in high-k metal gate MOS device with percolation simulation

    Science.gov (United States)

    Xu, Hao; Yang, Hong; Wang, Yan-Rong; Wang, Wen-Wu; Luo, Wei-Chun; Qi, Lu-Wei; Li, Jun-Feng; Zhao, Chao; Chen, Da-Peng; Ye, Tian-Chun

    2016-08-01

    High-k metal gate stacks are being used to suppress the gate leakage due to tunneling for sub-45 nm technology nodes. The reliability of thin dielectric films becomes a limitation to device manufacturing, especially to the breakdown characteristic. In this work, a breakdown simulator based on a percolation model and the kinetic Monte Carlo method is set up, and the intrinsic relation between time to breakdown and trap generation rate R is studied by TDDB simulation. It is found that all degradation factors, such as trap generation rate time exponent m, Weibull slope β and percolation factor s, each could be expressed as a function of trap density time exponent α. Based on the percolation relation and power law lifetime projection, a temperature related trap generation model is proposed. The validity of this model is confirmed by comparing with experiment results. For other device and material conditions, the percolation relation provides a new way to study the relationship between trap generation and lifetime projection. Project supported by the National High Technology Research and Development Program of China (Grant No. SS2015AA010601), the National Natural Science Foundation of China (Grant Nos. 61176091 and 61306129), and the Opening Project of Key Laboratory of Microelectronics Devices & Integrated Technology, Institute of MicroElectronics of Chinese Academy of Sciences.

  5. Assessment of High-Resolution Simulations of Precipitation and Temperature Characteristics Over Western Canada Using WRF Model

    Science.gov (United States)

    Asong, Z. E.

    2016-12-01

    Lack of accurate estimates of precipitation are an important limitation for hydrological and earth systems modelling in Canada. Ground-based measurements are inevitably limited, given the large land area and small population density, fail to capture the effects of mountain topography in important runoff-producing areas and suffer from gross inaccuracies associated with cold climate precipitation processes. The capability of the current generation of atmospheric models to represent precipitation is therefore of major interest for hydrological practice. The skill of a high-resolution 4-km convection resolving regional climate model (RCM)―Weather Research and Forecasting (WRF) in capturing the statistics of daily-scale precipitation (P) and temperature (T) over western Canada within the period 2002 - 2013, using observational data sets for comparison is evaluated in this study. We analyze not only the mean pattern of P and T distributions, but also the inter-annual variability and trends in higher order climate statistics such as wet-dry day frequency, spell lengths, 95th percentile daily maximum T, 5th percentile daily minimum T, and 95th percentile daily P are evaluated against ground observations. This preliminary assessment should enable more informed application of high-resolution RCMs for the investigation of current and future changes in socio-economic and environmentally relevant hydro-climatic characteristics over this topographically complex region of western Canada.

  6. A model for the computation of thermal expansivity at high compression and high temperatures - MGO as an example

    Science.gov (United States)

    Anderson, Orson L.; Oda, Hitoshi; Isaak, Donald

    1992-10-01

    The value of the thermal expansivity, alpha, over a wide range of compression, eta, and temperature is computed. Values of alpha for MgO over V,P,T conditions including those of the earth's lower mantle are suggested using a simple equation relating alpha to eta along isochores. The ab initio database is used to evaluate the parameters in the equation. The thermal expansivity is found to vary from about 1.40 alpha(a) to 0.40 alpha(a) along a geotherm through the upper and lower mantle, where alpha(a) is alpha at ambient conditions.

  7. Sensitivity of high-temperature weather to initial soil moisture: a case study using the WRF model

    Science.gov (United States)

    Zeng, X.-M.; Wang, B.; Zhang, Y.; Song, S.; Huang, X.; Zheng, Y.; Chen, C.; Wang, G.

    2014-09-01

    Using a succession of 24 h Weather Research and Forecasting model (WRF) simulations, we investigate the sensitivity to initial soil moisture of a short-range high-temperature weather event that occurred in late July 2003 in East China. The initial soil moisture (SMOIS) in the Noah land surface scheme is adjusted (relative to the control run, CTL) for four groups of simulations: DRY25 (-25%), DRY50 (-50%), WET25 (+25%) and WET50 (+50%). Ten 24 h integrations are performed in each group. We focus on 2 m surface air temperature (SAT) greater than 35 °C (the threshold of "high-temperature" events in China) at 06:00 UTC (roughly 14:00 LT in the study domain) to analyse the occurrence of the high-temperature event. The 10-day mean results show that the 06:00 UTC SAT (SAT06) is sensitive to the SMOIS change; specifically, SAT06 exhibits an apparent increase with the SMOIS decrease (e.g. compared with CTL, DRY25 generally results in a 1 °C SAT06 increase over the land surface of East China), areas with 35 °C or higher SAT06 are the most affected, and the simulations are more sensitive to the SMOIS decrease than to the SMOIS increase, which suggests that hot weather can be amplified under low soil moisture conditions. Regarding the mechanism underlying the extremely high SAT06, sensible heat flux has been shown to directly heat the lower atmosphere, and latent heat flux has been found to be more sensitive to the SMOIS change, resulting in an overall increase in surface net radiation due to the increased greenhouse effect (e.g. with the SMOIS increase from DRY25 to CTL, the 10-day mean net radiation increases by 5 W m-2). Additionally, due to the unique and dynamic nature of the western Pacific subtropical high, negative feedback occurs between the regional atmospheric circulation and the air temperature in the lower atmosphere while positive feedback occurs in the mid-troposphere. Using a method based on an analogous temperature relationship, a detailed analysis of the

  8. Dimensionality of high temperature superconductivity in oxides

    Science.gov (United States)

    Chu, C. W.

    1989-01-01

    Many models have been proposed to account for the high temperature superconductivity observed in oxide systems. Almost all of these models proposed are based on the uncoupled low dimensional carrier Cu-O layers of the oxides. Results of several experiments are presented and discussed. They suggest that the high temperature superconductivity observed cannot be strictly two- or one-dimensional, and that the environment between the Cu-O layers and the interlayer coupling play an important role in the occurrence of such high temperature superconductivity. A comment on the very short coherence length reported is also made.

  9. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...

  10. High Temperature Bell Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The National Research Council (NRC) has identified the need for motors and actuators that can operate in extreme high and low temperature environments as a technical...

  11. High Temperature Materials Laboratory (HTML)

    Data.gov (United States)

    Federal Laboratory Consortium — The six user centers in the High Temperature Materials Laboratory (HTML), a DOE User Facility, are dedicated to solving materials problems that limit the efficiency...

  12. Anharmonic phonons and high-temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Crespi, V.H.; Cohen, M.L. (Department of Physics, University of California at Berkeley, and Materials Sciences Division, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States))

    1993-07-01

    We examine a simple model of anharmonic phonons with application to the superconducting isotope effect. Linear and quadratic electron-phonon coupling are considered for various model potentials. The results of the model calculations are compared with the high-temperature superconductors La[sub 2[minus][ital x

  13. Hydrodynamic Effects on Modeling and Control of a High Temperature Active Magnetic Bearing Pump with a Canned Rotor

    Energy Technology Data Exchange (ETDEWEB)

    Melin, Alexander M [ORNL; Kisner, Roger A [ORNL; Fugate, David L [ORNL; Holcomb, David Eugene [ORNL

    2015-01-01

    Embedding instrumentation and control Embedding instrumentation and control (I\\&C) at the component level in nuclear power plants can improve component performance, lifetime, and resilience by optimizing operation, reducing the constraints on physical design, and providing on-board prognostics and diagnostics. However, the extreme environments that many nuclear power plant components operate in makes embedding instrumentation and control at the component level difficult. Successfully utilizing embedded I\\&C requires developing a deep understanding of the system's dynamics and using that knowledge to overcome material and physical limitations imposed by the environment. In this paper, we will develop a coupled dynamic model of a high temperature (700 $^\\circ$C) canned rotor pump that incorporates rotordynamics, hydrodynamics, and active magnetic bearing dynamics. Then we will compare two control design methods, one that uses a simplified decoupled model of the system and another that utilizes the full coupled system model. It will be seen that utilizing all the available knowledge of the system dynamics in the controller design yield an order of magnitude improvement in the magnitude of the magnetic bearing response to disturbances at the same level of control effort, a large reduction in the settling time of the system, and a smoother control action.

  14. Theoretical modeling of cutting temperature in high-speed end milling process for die/mold machining

    Institute of Scientific and Technical Information of China (English)

    Ying Tang

    2005-01-01

    A parametric model of cutting temperature generated in end milling process is developed according to the thermal mechanism of end milling as an intermittent operation, which periodically repeats the cycle of heating under cutting and cooling under noncutting. It shows that cutting speed and the tool-workpiece engagement condition are determinative for tool temperature in the operation. The suggested model was investigated by tests of AlTiN coated endmill machining hardened die steel JIS SKD61, where cutting temperature on the flank face of tool was measured with an optical fiber type radiation thermometer. Experimental results show that the tendency of cutting temperature to increase with cutting speed and engagement angle is intensified with the progressing tool wear.

  15. Gallium phosphide high temperature diodes

    Science.gov (United States)

    Chaffin, R. J.; Dawson, L. R.

    1981-01-01

    High temperature (300 C) diodes for geothermal and other energy applications were developed. A comparison of reverse leakage currents of Si, GaAs, and GaP was made. Diodes made from GaP should be usable to 500 C. A Liquid Phase Epitaxy (LPE) process for producing high quality, grown junction GaP diodes is described. This process uses low vapor pressure Mg as a dopant which allows multiple boat growth in the same LPE run. These LPE wafers were cut into die and metallized to make the diodes. These diodes produce leakage currents below ten to the -9th power A/sq cm at 400 C while exhibiting good high temperature rectification characteristics. High temperature life test data is presented which shows exceptional stability of the V-I characteristics.

  16. RPC operation at high temperature

    CERN Document Server

    Aielli, G; Cardarelli, R; Di Ciaccio, A; Di Stante, L; Liberti, B; Paoloni, A; Pastori, E; Santonico, R

    2003-01-01

    The resistive electrodes of RPCs utilised in several current experiments (ATLAS, CMS, ALICE, BABAR and ARGO) are made of phenolic /melaminic polymers, with room temperature resistivities ranging from 10**1**0 Omega cm, for high rate operation in avalanche mode, to 5 multiplied by 10**1**1 Omega cm, for streamer mode operation at low rate. The resistivity has however a strong temperature dependence, decreasing exponentially with increasing temperature. We have tested several RPCs with different electrode resistivities in avalanche as well as in streamer mode operation. The behaviours of the operating current and of the counting rate have been studied at different temperatures. Long-term operation has also been studied at T = 45 degree C and 35 degree C, respectively, for high and low resistivity electrodes RPCs.

  17. Temperature optimization of high con

    Directory of Open Access Journals (Sweden)

    M. Sabry

    2016-06-01

    Full Text Available Active cooling is essential for solar cells operating under high optical concentration ratios. A system comprises four solar cells that are in thermal contact on top of a copper tube is proposed. Water is flowing inside the tube in order to reduce solar cells temperature for increasing their performance. Computational Fluid Dynamics (CFD simulation of such system has been performed in order to investigate the effect of water flow rate, tube internal diameter, and convective heat transfer coefficient on the temperature of the solar cells. It is found that increasing convective heat transfer coefficient has a significant effect on reducing solar cells temperatures operating at low flow rates and high optical concentration ratios. Also, a further increase of water flow rate has no effect on reducing cells temperatures.

  18. Model based predictive control of a high temperature gas cooled power plant coupled to a hydrogen production facility

    Science.gov (United States)

    Rhoads, Lloyd A.

    This thesis builds upon recent studies focusing on modeling, operation, and control of high temperature gas cooled reactors. A computer model was developed, based on mass, energy, and momentum balances of control volumes throughout the plant. Several simulations of the plant behavior were conducted and their results were compared with those from the literature. Proportional control was combined with optimal control to form a time varying, adjustable gain predictive controller which adjusts the proportional gains during transients. The controller was designed to utilize control rod motions and bypass control valves to maintain desired plant conditions. An optimization scheme was introduced to efficiently solve the optimization problem formulated as part of the predictive controller operation. Several additional transients were run to examine the full plant controller performance. Multiple predictive controllers were designed and their performance was compared with a proportional controller throughout each transient. The predictive controller results confirmed the importance of proper selection of the optimal controller parameters, in particular the controller time step size and the horizon time. The well-designed proportional controllers clearly demonstrated improvements in plant performance during short time scale transients, namely a loss of secondary heat transfer transient and a step change in desired power transient. Results from long time scale transients demonstrated the capabilities of the proposed bypass control system to control electrical power production without the need for storage vessels.

  19. HIGH TEMPERATURE POLYMER FUEL CELLS

    DEFF Research Database (Denmark)

    Jensen, Jens Oluf; Qingfeng, Li; He, Ronghuan

    2003-01-01

    This paper will report recent results from our group on polymer fuel cells (PEMFC) based on the temperature resistant polymer polybenzimidazole (PBI), which allow working temperatures up to 200°C. The membrane has a water drag number near zero and need no water management at all. The high working...... temperature allows for utilization of the excess heat for fuel processing. Moreover, it provides an excellent CO tolerance of several percent, and the system needs no purification of hydrogen from a reformer. Continuous service for over 6 months at 150°C has been demonstrated....

  20. Critical universality and hyperscaling revisited for Ising models of general spin using extended high-temperature series

    CERN Document Server

    Butera, P

    2002-01-01

    We have extended through beta^{23} the high-temperature expansion of the second field derivative of the susceptibility for Ising models of general spin, with nearest-neighbor interactions, on the simple cubic and the body-centered cubic lattices. Moreover the expansions for the nearest-neighbor correlation function, the susceptibility and the second correlation moment have been extended up to beta^{25}. Taking advantage of these new data, we can improve the accuracy of direct estimates of critical exponents and of hyper-universal combinations of critical amplitudes such as the renormalized four-point coupling g_r or the quantity usually denoted by R^{+}_{xi}. We have used a variety of series extrapolation procedures and, in some of the analyses, we have assumed that the leading correction-to-scaling exponent theta is universal and roughly known. We have also verified, to high precision, the validity of the hyperscaling relation and of the universality property both with regard to the lattice structure and to ...

  1. Interface high-temperature superconductivity

    Science.gov (United States)

    Wang, Lili; Ma, Xucun; Xue, Qi-Kun

    2016-12-01

    Cuprate high-temperature superconductors consist of two quasi-two-dimensional (2D) substructures: CuO2 superconducting layers and charge reservoir layers. The superconductivity is realized by charge transfer from the charge reservoir layers into the superconducting layers without chemical dopants and defects being introduced into the latter, similar to modulation-doping in the semiconductor superlattices of AlGaAs/GaAs. Inspired by this scheme, we have been searching for high-temperature superconductivity in ultra-thin films of superconductors epitaxially grown on semiconductor/oxide substrates since 2008. We have observed interface-enhanced superconductivity in both conventional and unconventional superconducting films, including single atomic layer films of Pb and In on Si substrates and single unit cell (UC) films of FeSe on SrTiO3 (STO) substrates. The discovery of high-temperature superconductivity with a superconducting gap of ∼20 meV in 1UC-FeSe/STO has stimulated tremendous interest in the superconductivity community, for it opens a new avenue for both raising superconducting transition temperature and understanding the pairing mechanism of unconventional high-temperature superconductivity. Here, we review mainly the experimental progress on interface-enhanced superconductivity in the three systems mentioned above with emphasis on 1UC-FeSe/STO, studied by scanning tunneling microscopy/spectroscopy, angle-resolved photoemission spectroscopy and transport experiments. We discuss the roles of interfaces and a possible pairing mechanism inferred from these studies.

  2. High-Temperature Optical Sensor

    Science.gov (United States)

    Adamovsky, Grigory; Juergens, Jeffrey R.; Varga, Donald J.; Floyd, Bertram M.

    2010-01-01

    A high-temperature optical sensor (see Figure 1) has been developed that can operate at temperatures up to 1,000 C. The sensor development process consists of two parts: packaging of a fiber Bragg grating into a housing that allows a more sturdy thermally stable device, and a technological process to which the device is subjected to in order to meet environmental requirements of several hundred C. This technology uses a newly discovered phenomenon of the formation of thermally stable secondary Bragg gratings in communication-grade fibers at high temperatures to construct robust, optical, high-temperature sensors. Testing and performance evaluation (see Figure 2) of packaged sensors demonstrated operability of the devices at 1,000 C for several hundred hours, and during numerous thermal cycling from 400 to 800 C with different heating rates. The technology significantly extends applicability of optical sensors to high-temperature environments including ground testing of engines, flight propulsion control, thermal protection monitoring of launch vehicles, etc. It may also find applications in such non-aerospace arenas as monitoring of nuclear reactors, furnaces, chemical processes, and other hightemperature environments where other measurement techniques are either unreliable, dangerous, undesirable, or unavailable.

  3. High temperature superconductor current leads

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL); Poeppel, Roger B. (Glen Ellyn, IL)

    1995-01-01

    An electrical lead having one end for connection to an apparatus in a cryogenic environment and the other end for connection to an apparatus outside the cryogenic environment. The electrical lead includes a high temperature superconductor wire and an electrically conductive material distributed therein, where the conductive material is present at the one end of the lead at a concentration in the range of from 0 to about 3% by volume, and at the other end of the lead at a concentration of less than about 20% by volume. Various embodiments are shown for groups of high temperature superconductor wires and sheaths.

  4. High temperature polymer matrix composites

    Science.gov (United States)

    Serafini, Tito T. (Editor)

    1987-01-01

    These are the proceedings of the High Temperature Polymer Matrix Composites Conference held at the NASA Lewis Research Center on March 16 to 18, 1983. The purpose of the conference is to provide scientists and engineers working in the field of high temperature polymer matrix composites an opportunity to review, exchange, and assess the latest developments in this rapidly expanding area of materials technology. Technical papers are presented in the following areas: (1) matrix development; (2) adhesive development; (3) Characterization; (4) environmental effects; and (5) applications.

  5. High temperature corrosion in gasifiers

    Directory of Open Access Journals (Sweden)

    Bakker Wate

    2004-01-01

    Full Text Available Several commercial scale coal gasification combined cycle power plants have been built and successfully operated during the last 5-10 years. Supporting research on materials of construction has been carried out for the last 20 years by EPRI and others. Emphasis was on metallic alloys for heat exchangers and other components in contact with hot corrosive gases at high temperatures. In this paper major high temperature corrosion mechanisms, materials performance in presently operating gasifiers and future research needs will be discussed.

  6. High-temperature Titanium Alloys

    Directory of Open Access Journals (Sweden)

    A.K. Gogia

    2005-04-01

    Full Text Available The development of high-temperature titanium alloys has contributed significantly to the spectacular progress in thrust-to-weight ratio of the aero gas turbines. This paper presents anoverview on the development of high-temperature titanium alloys used in aero engines and potential futuristic materials based on titanium aluminides and composites. The role of alloychemistry, processing, and microstructure, in determining the mechanical properties of titanium alloys is discussed. While phase equilibria and microstructural stability consideration haverestricted the use of conventional titanium alloys up to about 600 "C, alloys based on TiPl (or,, E,AINb (0, TiAl (y, and titaniumltitanium aluminides-based composites offer a possibility ofquantum jump in the temperature capability of titanium alloys.

  7. Chemistry of high temperature superconductors

    CERN Document Server

    1991-01-01

    This review volume contains the most up-to-date articles on the chemical aspects of high temperature oxide superconductors. These articles are written by some of the leading scientists in the field and includes a comprehensive list of references. This is an essential volume for researchers working in the fields of ceramics, materials science and chemistry.

  8. Properties of high temperature SQUIDS

    Energy Technology Data Exchange (ETDEWEB)

    Falco, C. M.; Wu, C. T.

    1978-01-01

    A review is given of the present status of weak links and dc and rf biased SQUIDs made with high temperature superconductors. A method for producing reliable, reproducible devices using Nb/sub 3/Sn is outlined, and comments are made on directions future work should take.

  9. Channel Temperature Model for Microwave AlGaN/GaN HEMTs on SiC and Sapphire MMICs in High Power, High Efficiency SSPAs

    Science.gov (United States)

    Freeman, Jon C.

    2004-01-01

    A key parameter in the design trade-offs made during AlGaN/GaN HEMTs development for microwave power amplifiers is the channel temperature. An accurate determination can, in general, only be found using detailed software; however, a quick estimate is always helpful, as it speeds up the design cycle. This paper gives a simple technique to estimate the channel temperature of a generic microwave AlGaN/GaN HEMT on SiC or Sapphire, while incorporating the temperature dependence of the thermal conductivity. The procedure is validated by comparing its predictions with the experimentally measured temperatures in microwave devices presented in three recently published articles. The model predicts the temperature to within 5 to 10 percent of the true average channel temperature. The calculation strategy is extended to determine device temperature in power combining MMICs for solid-state power amplifiers (SSPAs).

  10. High temperature suppression of dioxins.

    Science.gov (United States)

    Zhan, Ming-Xiu; Chen, Tong; Fu, Jian-Ying; Lin, Xiao-Qing; Lu, Sheng-Yong; Li, Xiao-Dong; Yan, Jian-Hua; Buekens, Alfons

    2016-03-01

    Combined Sulphur-Nitrogen inhibitors, such as sewage sludge decomposition gases (SDG), thiourea and amidosulphonic acid have been observed to suppress the de novo synthesis of dioxins effectively. In this study, the inhibition of PCDD/Fs formation from model fly ash was investigated at unusually high temperatures (650 °C and 850 °C), well above the usual range of de novo tests (250-400 °C). At 650 °C it was found that SDG evolving from dried sewage sludge could suppress the formation of 2,3,7,8-substituted PCDD/Fs with high efficiency (90%), both in weight units and in I-TEQ units. Additionally, at 850 °C, three kinds of sulphur-amine or sulphur-ammonium compounds were tested to inhibit dioxins formation during laboratory-scale tests, simulating municipal solid waste incineration. The suppression efficiencies of PCDD/Fs formed through homogeneous gas phase reactions were all above 85% when 3 wt. % of thiourea (98.7%), aminosulphonic acid (96.0%) or ammonium thiosulphate (87.3%) was added. Differences in the ratio of PCDFs/PCDDs, in weight average chlorination level and in the congener distribution of the 17 toxic PCDD/Fs indicated that the three inhibitors tested followed distinct suppression pathways, possibly in relation to their different functional groups of nitrogen. Furthermore, thiourea reduced the (weight) average chlorinated level. In addition, the thermal decomposition of TUA was studied by means of thermogravimetry-fourier transform infrared spectroscopy (TG-FTIR) and the presence of SO2, SO3, NH3 and nitriles (N≡C bonds) was shown in the decomposition gases; these gaseous inhibitors might be the primary dioxins suppressants.

  11. Laser Plasma Coupling for High Temperature Hohlraums

    Energy Technology Data Exchange (ETDEWEB)

    Kruer, W.

    1999-11-04

    Simple scaling models indicate that quite high radiation temperatures can be achieved in hohlraums driven with the National Ignition Facility. A scaling estimate for the radiation temperature versus pulse duration for different size NIF hohlraums is shown in Figure 1. Note that a radiation temperature of about 650 ev is projected for a so-called scale 1 hohlraum (length 2.6mm, diameter 1.6mm). With such high temperature hohlraums, for example, opacity experiments could be carried out using more relevant high Z materials rather than low Z surrogates. These projections of high temperature hohlraums are uncertain, since the scaling model does not allow for the very strongly-driven laser plasma coupling physics. Lasnex calculations have been carried out to estimate the plasma and irradiation conditions in a scale 1 hohlraum driven by NIF. Linear instability gains as high as exp(100) have been found for stimulated Brillouin scattering, and other laser-driven instabilities are also far above their thresholds. More understanding of the very strongly-driven coupling physics is clearly needed in order to more realistically assess and improve the prospects for high temperature hohlraums. Not surprisingly, this regime has been avoided for inertial fusion applications and so is relatively unexplored.

  12. Parsing multiple processes of high temperature impacts on corn/soybean yield using a newly developed CLM-APSIM modeling framework

    Science.gov (United States)

    Peng, B.; Guan, K.; Chen, M.

    2016-12-01

    Future agricultural production faces a grand challenge of higher temperature under climate change. There are multiple physiological or metabolic processes of how high temperature affects crop yield. Specifically, we consider the following major processes: (1) direct temperature effects on photosynthesis and respiration; (2) speed-up growth rate and the shortening of growing season; (3) heat stress during reproductive stage (flowering and grain-filling); (4) high-temperature induced increase of atmospheric water demands. In this work, we use a newly developed modeling framework (CLM-APSIM) to simulate the corn and soybean growth and explicitly parse the above four processes. By combining the strength of CLM in modeling surface biophysical (e.g., hydrology and energy balance) and biogeochemical (e.g., photosynthesis and carbon-nitrogen interactions), as well as that of APSIM in modeling crop phenology and reproductive stress, the newly developed CLM-APSIM modeling framework enables us to diagnose the impacts of high temperature stress through different processes at various crop phenology stages. Ground measurements from the advanced SoyFACE facility at University of Illinois is used here to calibrate, validate, and improve the CLM-APSIM modeling framework at the site level. We finally use the CLM-APSIM modeling framework to project crop yield for the whole US Corn Belt under different climate scenarios.

  13. High temperature, high power piezoelectric composite transducers.

    Science.gov (United States)

    Lee, Hyeong Jae; Zhang, Shujun; Bar-Cohen, Yoseph; Sherrit, Stewart

    2014-08-08

    Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  14. High Temperature, High Power Piezoelectric Composite Transducers

    Directory of Open Access Journals (Sweden)

    Hyeong Jae Lee

    2014-08-01

    Full Text Available Piezoelectric composites are a class of functional materials consisting of piezoelectric active materials and non-piezoelectric passive polymers, mechanically attached together to form different connectivities. These composites have several advantages compared to conventional piezoelectric ceramics and polymers, including improved electromechanical properties, mechanical flexibility and the ability to tailor properties by using several different connectivity patterns. These advantages have led to the improvement of overall transducer performance, such as transducer sensitivity and bandwidth, resulting in rapid implementation of piezoelectric composites in medical imaging ultrasounds and other acoustic transducers. Recently, new piezoelectric composite transducers have been developed with optimized composite components that have improved thermal stability and mechanical quality factors, making them promising candidates for high temperature, high power transducer applications, such as therapeutic ultrasound, high power ultrasonic wirebonding, high temperature non-destructive testing, and downhole energy harvesting. This paper will present recent developments of piezoelectric composite technology for high temperature and high power applications. The concerns and limitations of using piezoelectric composites will also be discussed, and the expected future research directions will be outlined.

  15. High Temperature Sorbents for Oxygen

    Science.gov (United States)

    Sharma, Pramod K. (Inventor)

    1996-01-01

    A sorbent capable of removing trace amounts of oxygen (ppt) from a gas stream at a high temperature above 200 C is introduced. The sorbent comprises a porous alumina silicate support such as zeolite containing from 1 to 10 percent by weight of ion exchanged transition metal such as copper or cobalt ions and 0.05 to 1.0 percent by weight of an activator selected from a platinum group metal such as platinum. The activation temperature, oxygen sorption and reducibility are all improved by the presence of the platinum activator.

  16. A dynamic response model for pressure sensors in continuum and high Knudsen number flows with large temperature gradients

    Science.gov (United States)

    Whitmore, Stephen A.; Petersen, Brian J.; Scott, David D.

    1996-01-01

    This paper develops a dynamic model for pressure sensors in continuum and rarefied flows with longitudinal temperature gradients. The model was developed from the unsteady Navier-Stokes momentum, energy, and continuity equations and was linearized using small perturbations. The energy equation was decoupled from momentum and continuity assuming a polytropic flow process. Rarefied flow conditions were accounted for using a slip flow boundary condition at the tubing wall. The equations were radially averaged and solved assuming gas properties remain constant along a small tubing element. This fundamental solution was used as a building block for arbitrary geometries where fluid properties may also vary longitudinally in the tube. The problem was solved recursively starting at the transducer and working upstream in the tube. Dynamic frequency response tests were performed for continuum flow conditions in the presence of temperature gradients. These tests validated the recursive formulation of the model. Model steady-state behavior was analyzed using the final value theorem. Tests were performed for rarefied flow conditions and compared to the model steady-state response to evaluate the regime of applicability. Model comparisons were excellent for Knudsen numbers up to 0.6. Beyond this point, molecular affects caused model analyses to become inaccurate.

  17. High temperature internal friction measurements of 3YTZP zirconia polycrystals. High temperature background and creep

    OpenAIRE

    Simas, P.; Castillo-Rodríguez, Miguel; Nó, M. L.; De-Bernardi, S.; Gómez-García, D.; Domínguez-Rodríguez, Alejandro; San Juan, J.

    2014-01-01

    This work focuses on the high-temperature mechanic properties of a 3 mol % yttria zirconia polycrystals (3YTZP), fabricated by hot-pressureless sintering. Systematic measurements of mechanical loss as a function of temperature and frequency were performed. An analytical method, based on the generalised Maxwell rheological model, has been used to analyse the high temperature internal friction background (HTB). This method has been previously applied to intermetallic compounds...

  18. High-temperature beryllium embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Pokrovsky, A.S. [Scientific Research Inst. of Atomic Reactors, Dimitrovgrad (Russian Federation); Fabritsiev, S.A. [D.V. Efremov Scientific Research Institute, 189631 St. Petersburg (Russian Federation); Bagautdinov, R.M. [Scientific Research Inst. of Atomic Reactors, Dimitrovgrad (Russian Federation); Goncharenko, Yu.D. [Scientific Research Inst. of Atomic Reactors, Dimitrovgrad (Russian Federation)

    1996-10-01

    The neutron irradiation effect on the mechanical properties, swelling and fracture surface structure of various beryllium grades was studied in the BOR-60 reactor at 340 to 350 C up to a fluence of 7.2 x 10{sup 21} n/cm{sup 2}. At a mechanical testing temperature of 400 C there was observed a strong anisotropy of plastic beryllium deformation depending on the direction of sample cutting relative to the pressing direction. An increase of the testing temperature up to 700 C resulted in an abrupt embrittlement of all irradiated samples. In the most part of the surface structure the intercrystallite fracture along the grain boundaries was covered entirely with large pores, 1 to 4 {mu}m in size. It was suggested that the increased rate of pore formation along the grain boundaries resulted from a high-temperature embrittlement under irradiation. (orig.).

  19. High temperature superconductors applications in telecommunications

    Science.gov (United States)

    Kumar, A. Anil; Li, Jiang; Zhang, Ming Fang

    1995-01-01

    The purpose of this paper is twofold: (1) to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and (2) to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices - obvious advantages versus practical difficulties - needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models - a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B) - shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance - conductivity, surface resistance and attenuation constant - will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T

  20. High temperature superconductors applications in telecommunications

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A.A.; Li, J.; Zhang, M.F. [Prairie View A& M Univ., Texas (United States)

    1994-12-31

    The purpose of this paper is twofold: to discuss high temperature superconductors with specific reference to their employment in telecommunications applications; and to discuss a few of the limitations of the normally employed two-fluid model. While the debate on the actual usage of high temperature superconductors in the design of electronic and telecommunications devices-obvious advantages versus practical difficulties-needs to be settled in the near future, it is of great interest to investigate the parameters and the assumptions that will be employed in such designs. This paper deals with the issue of providing the microwave design engineer with performance data for such superconducting waveguides. The values of conductivity and surface resistance, which are the primary determining factors of a waveguide performance, are computed based on the two-fluid model. A comparison between two models-a theoretical one in terms of microscopic parameters (termed Model A) and an experimental fit in terms of macroscopic parameters (termed Model B)-shows the limitations and the resulting ambiguities of the two-fluid model at high frequencies and at temperatures close to the transition temperature. The validity of the two-fluid model is then discussed. Our preliminary results show that the electrical transport description in the normal and superconducting phases as they are formulated in the two-fluid model needs to be modified to incorporate the new and special features of high temperature superconductors. Parameters describing the waveguide performance-conductivity, surface resistance and attenuation constant-will be computed. Potential applications in communications networks and large scale integrated circuits will be discussed. Some of the ongoing work will be reported. In particular, a brief proposal is made to investigate of the effects of electromagnetic interference and the concomitant notion of electromagnetic compatibility (EMI/EMC) of high T{sub c} superconductors.

  1. The multiscale modeling and data mining of high-temperature dielectrics of SiO2/SiO2 composites

    Institute of Scientific and Technical Information of China (English)

    YUAN Jie; CUI Chao; HOU Zhi-ling; CAO Mao-sheng

    2007-01-01

    The high temperature dielectrics of Quartz fiber-reinforced silicon dioxide ceramic (SiO2/SiO2 ) composites were studied both theoretically and experimentally. A multi-scale theoretical model was developed based on the theory of dielectrics. It was realized to predict dielectric properties at higher temperature ( > 1200 ℃) by experimental data mining for correlative coefficients in model. The results show that the dielectrics of SiO2/SiO2,which were calculated with the theoretical model, were in agreement with experimental measured value.

  2. Modeling the splitting of thin silicon films from porosified crystalline silicon upon high temperature annealing in hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Ghannam, Moustafa Y.; Raheem, Yaser Abdul; Alomar, Abdul Azeez [EE Department, College of Engineering and Petroleum, Kuwait University, Safat (Kuwait); Poortmans, Jef [IMEC, Leuven (Belgium)

    2012-10-15

    The role of hydrogen in promoting thin film splitting from crystalline silicon wafers with pores or trenches during high temperature annealing is investigated. During the treatment, trenches are transformed into spherical voids that may laterally channel and split off the substrate. It is shown that the conditions necessary for hydrogen to contribute to the establishment of high stress levels around transformed voids or of pressure inside the voids are usually not satisfied. Hence promoting void coalescence by substantial void volume growth resulting from stress enhanced vacancy diffusion and/or exfoliation of separated voids are unlikely to occur. Also, there are no experimental evidence that confirms the role of hydrogen in triggering premature void collapse by Griffith fracture at relatively lower stress levels in conjunction with reduced surface energy. Therefore, it is concluded that splitting occurs during high temperature annealing only when neighboring voids are close enough to systematically coalesce. In that case, hydrogen may react at high temperature with the internal silicon surface of the voids (walls) and contribute to breaking the thin straps separating the voids which promotes channelling and film splitting (copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  3. Constitutive modeling and finite element procedure development for stress analysis of prismatic high temperature gas cooled reactor graphite core components

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov [Argonne National Laboratory, South Cass Avenue, Argonne, IL 60439 (United States); Majumdar, Saurindranath [Argonne National Laboratory, South Cass Avenue, Argonne, IL 60439 (United States); Srinivasan, Makuteswara [U.S. Nuclear Regulatory Commission, Washington, DC 20555 (United States)

    2013-07-15

    Highlights: • Finite element procedure developed for stress analysis of HTGR graphite component. • Realistic fluence profile and reflector brick shape considered for the simulation. • Also realistic H-451 grade material properties considered for simulation. • Typical outer reflector of a GT-MHR type reactor considered for numerical study. • Based on the simulation results replacement of graphite bricks can be scheduled. -- Abstract: High temperature gas cooled reactors, such as prismatic and pebble bed reactors, are increasingly becoming popular because of their inherent safety, high temperature process heat output, and high efficiency in nuclear power generation. In prismatic reactors, hexagonal graphite bricks are used as reflectors and fuel bricks. In the reactor environment, graphite bricks experience high temperature and neutron dose. This leads to dimensional changes (swelling and or shrinkage) of these bricks. Irradiation dimensional changes may affect the structural integrity of the individual bricks as well as of the overall core. The present paper presents a generic procedure for stress analysis of prismatic core graphite components using graphite reflector as an example. The procedure is demonstrated through commercially available ABAQUS finite element software using the option of user material subroutine (UMAT). This paper considers General Atomics Gas Turbine-Modular Helium Reactor (GT-MHR) as a bench mark design to perform the time integrated stress analysis of a typical reflector brick considering realistic geometry, flux distribution and realistic irradiation material properties of transversely isotropic H-451 grade graphite.

  4. High Temperature Heat Exchanger Project

    Energy Technology Data Exchange (ETDEWEB)

    Anthony E. Hechanova, Ph.D.

    2008-09-30

    The UNLV Research Foundation assembled a research consortium for high temperature heat exchanger design and materials compatibility and performance comprised of university and private industry partners under the auspices of the US DOE-NE Nuclear Hydrogen Initiative in October 2003. The objectives of the consortium were to conduct investigations of candidate materials for high temperature heat exchanger componets in hydrogen production processes and design and perform prototypical testing of heat exchangers. The initial research of the consortium focused on the intermediate heat exchanger (located between the nuclear reactor and hydrogen production plan) and the components for the hydrogen iodine decomposition process and sulfuric acid decomposition process. These heat exchanger components were deemed the most challenging from a materials performance and compatibility perspective

  5. Motor for High Temperature Applications

    Science.gov (United States)

    Roopnarine (Inventor)

    2013-01-01

    A high temperature motor has a stator with poles formed by wire windings, and a rotor with magnetic poles on a rotor shaft positioned coaxially within the stator. The stator and rotor are built up from stacks of magnetic-alloy laminations. The stator windings are made of high temperature magnet wire insulated with a vitreous enamel film, and the wire windings are bonded together with ceramic binder. A thin-walled cylinder is positioned coaxially between the rotor and the stator to prevent debris from the stator windings from reaching the rotor. The stator windings are wound on wire spools made of ceramic, thereby avoiding need for mica insulation and epoxy/adhesive. The stator and rotor are encased in a stator housing with rear and front end caps, and rear and front bearings for the rotor shaft are mounted on external sides of the end caps to keep debris from the motor migrating into the bearings' races.

  6. Very High Temperature Sound Absorption Coating Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Phase I demonstrated experimentally a very high temperature acoustically absorbing coating for ducted acoustics applications. High temperature survivability at 3500...

  7. Using TOUGH2/ECO2H for modeling high-pressure and high-temperature CO2-enhanced geothermal energy extraction from saline systems

    Science.gov (United States)

    Borgia, A.; Pruess, K.; Kneafsey, T. J.; Oldenburg, C. M.

    2011-12-01

    Conventional geothermal energy uses water as the fluid to transport heat to the surface. This has a number of drawbacks principally related to strong water-rock chemical reactions, but also in terms of environmental impacts through overdraft of shallow aquifers with valuable water resources. Various authors have proposed the use of CO2 instead of water to transfer heat because such use may result in better rate of heat extraction, less fluid-rock reactivity, and less demand for scarce ground or surface water resources. TOUGH2/ECO2H was developed to study the behavior of high-pressure high-temperature H2O-CO2-NaCl geothermal systems. To demonstrate and test the code, we have modeled an idealized fractured geothermal system. Based on a five-spot well pattern and its inherent symmetry, we use a model grid of 1/8 of a square with sides of 1 km. In the model, CO2 is injected at the four corner-wells at 20 °C and constant pressure of 2.1*10^7 Pa into a variable salinity reservoir which is initially at 200 °C. The center well produces fluid at a constant pressure of 1.9*10^7 Pa. Initially, H2O + NaCl are produced, followed by a mixture of H2O + CO2 + NaCl and, finally only CO2. As soon as the injected CO2 reaches the production well, usually less than 2 months after injection begins, there is a drastic drop in heat production. This decrease occurs because of a reduced flow rate induced by reduction in effective permeability associated with two-phase flow (liquid + gas) in the reservoir. As the liquid phase dries out, the CO2 flow rate increases slowly over about 2-3 years and the heat production reaches a maximum rate that is about 40% larger than the initial rate of production with just water. Our modeling suggests that this same behavior occurs for highly saline geothermal reservoirs, even though the absolute rate of heat production is about 30% lower than the non-saline models. The decrease in production for saline systems is due to a marked reduction in permeability

  8. Modelling of heat and mass transfer in a granular medium during high-temperature air drying. Effect of the internal gas pressure

    Science.gov (United States)

    Othmani, Hammouda; Hassini, Lamine; Lamloumi, Raja; El Cafsi, Mohamed Afif

    2016-02-01

    A comprehensive internal heat and water transfer model including the gas pressure effect has been proposed in order to improve the industrial high-temperature air drying of inserts made of agglomerated sand. In this model, the internal gas phase pressure effect was made perfectly explicit, by considering the liquid and vapour transfer by filtration and the liquid expulsion at the surface. Wet sand enclosed in a tight cylindrical glass bottle dried convectively at a high temperature was chosen as an application case. The model was validated on the basis of the experimental average water content and core temperature curves for drying trials at different operating conditions. The simulations of the spatio-temporal distribution of internal gas pressure were performed and interpreted in terms of product potential damage. Based on a compromise between the drying time and the pressure increase, a simple drying cycle was implemented in order to optimize the drying process.

  9. Fluctuations and correlations in high temperature QCD

    CERN Document Server

    Bellwied, R; Fodor, Z; Katz, S D; Pasztor, A; Ratti, C; Szabo, K K

    2015-01-01

    We calculate second- and fourth-order cumulants of conserved charges in a temperature range stretching from the QCD transition region towards the realm of (resummed) perturbation theory. We perform lattice simulations with staggered quarks; the continuum extrapolation is based on $N_t=10\\dots24$ in the crossover-region and $N_t=8\\dots16$ at higher temperatures. We find that the Hadron Resonance Gas model predictions describe the lattice data rather well in the confined phase. At high temperatures (above $\\sim$250 MeV) we find agreement with the three-loop Hard Thermal Loop results.

  10. The Transition of High-Resolution NASA MODIS Sea Surface Temperatures into the WRF Environmental Modeling System

    Science.gov (United States)

    Case, Jonathan L.; Jedlove, Gary J.; Santos, Pablo; Medlin, Jeffrey M.; Rozumalski, Robert A.

    2009-01-01

    The NASA Short-term Prediction Research and Transition (SPoRT) Center has developed a Moderate Resolution Imaging Spectroradiometer (MODIS) sea surface temperature (SST) composite at 2-km resolution that has been implemented in version 3 of the National Weather Service (NWS) Weather Research and Forecasting (WRF) Environmental Modeling System (EMS). The WRF EMS is a complete, full physics numerical weather prediction package that incorporates dynamical cores from both the Advanced Research WRF (ARW) and the Non-hydrostatic Mesoscale Model (NMM). The installation, configuration, and execution of either the ARW or NMM models is greatly simplified by the WRF EMS to encourage its use by NWS Weather Forecast Offices (WFOs) and the university community. The WRF EMS is easy to run on most Linux workstations and clusters without the need for compilers. Version 3 of the WRF EMS contains the most recent public release of the WRF-NMM and ARW modeling system (version 3 of the ARW is described in Skamarock et al. 2008), the WRF Pre-processing System (WPS) utilities, and the WRF Post-Processing program. The system is developed and maintained by the NWS National Science Operations Officer Science and Training Resource Coordinator. To initialize the WRF EMS with high-resolution MODIS SSTs, SPoRT developed the composite product consisting of MODIS SSTs over oceans and large lakes with the NCEP Real-Time Global (RTG) filling data over land points. Filling the land points is required due to minor inconsistencies between the WRF land-sea mask and that used to generate the MODIS SST composites. This methodology ensures a continuous field that adequately initializes all appropriate arrays in WRF. MODIS composites covering the Gulf of Mexico, western Atlantic Ocean and the Caribbean are generated daily at 0400, 0700, 1600, and 1900 UTC corresponding to overpass times of the NASA Aqua and Terra polar orbiting satellites. The MODIS SST product is output in gridded binary-1 (GRIB-1) data

  11. Temperature uniformity mapping in a high pressure high temperature reactor using a temperature sensitive indicator

    NARCIS (Netherlands)

    Grauwet, T.; Plancken, van der I.; Vervoort, L.; Matser, A.M.; Hendrickx, M.; Loey, van A.

    2011-01-01

    Recently, the first prototype ovomucoid-based pressure–temperature–time indicator (pTTI) for high pressure high temperature (HPHT) processing was described. However, for temperature uniformity mapping of high pressure (HP) vessels under HPHT sterilization conditions, this prototype needs to be optim

  12. A modified phase coherence model for the non-linear c-axis V-I characteristics of highly anisotropic, high temperature superconductors

    CERN Document Server

    Luo Sheng; Huang Sai Jun; He Yu Sheng; Li Chun Guang; Zhang Xue Qiang

    2003-01-01

    A modified Ambegaokar-Halperin thermal-fluctuation model has been developed to describe the c-axis V-I characteristics and low-current ohmic resistance of highly anisotropic superconductors in a magnetic field parallel to the c-axis. The model assumes loss of phase coherence across the CuO-planes associated with the correlated motion of pancake vortices in the liquid state. The predicted V-I characteristics in the current-induced transition from the superconducting to the resistive state are in good agreement with measurements on a 2212-BSCCO single crystal as a function of temperature and field, provided the effect of the interlayer capacitance is taken into account. The measurements are consistent with a flux pancake correlation length within the CuO-planes varying as xi sub 0 /(T/T sub 0 - 1) supnu, where xi sub 0 = 1.57 +- 0.08 mu m and nu = 0.50 +- 0.01. Our measurements imply a current-dependent interlayer resistance above and below T sub c.

  13. System model development for a methanol reformed 5 kW high temperature PEM fuel cell system

    DEFF Research Database (Denmark)

    Sahlin, Simon Lennart; Andreasen, Søren Juhl; Kær, Søren Knudsen

    2015-01-01

    This work investigates the system performance when reforming methanol in an oil heated reformer system for a 5 kW fuel cell system. A dynamic model of the system is created and evaluated. The system is divided into 4 separate components. These components are the fuel cell, reformer, burner...... and evaporator, which are connected by two separate oil circuits, one with a burner and reformer and one with a fuel cell and evaporator. Experiments were made on the reformer and measured oil and bed temperatures are presented in multiple working points. The system is examined at loads from 0 to 5000 W electric...

  14. Passivation of high temperature superconductors

    Science.gov (United States)

    Vasquez, Richard P. (Inventor)

    1991-01-01

    The surface of high temperature superconductors such as YBa2Cu3O(7-x) are passivated by reacting the native Y, Ba and Cu metal ions with an anion such as sulfate or oxalate to form a surface film that is impervious to water and has a solubility in water of no more than 10(exp -3) M. The passivating treatment is preferably conducted by immersing the surface in dilute aqueous acid solution since more soluble species dissolve into the solution. The treatment does not degrade the superconducting properties of the bulk material.

  15. Application of a Coated Film Catalyst Layer Model to a High Temperature Polymer Electrolyte Membrane Fuel Cell with Low Catalyst Loading Produced by Reactive Spray Deposition Technology

    Directory of Open Access Journals (Sweden)

    Timothy D. Myles

    2015-10-01

    Full Text Available In this study, a semi-empirical model is presented that correlates to previously obtained experimental overpotential data for a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC. The goal is to reinforce the understanding of the performance of the cell from a modeling perspective. The HT-PEMFC membrane electrode assemblies (MEAs were constructed utilizing an 85 wt. % phosphoric acid doped Advent TPS® membranes for the electrolyte and gas diffusion electrodes (GDEs manufactured by Reactive Spray Deposition Technology (RSDT. MEAs with varying ratios of PTFE binder to carbon support material (I/C ratio were manufactured and their performance at various operating temperatures was recorded. The semi-empirical model derivation was based on the coated film catalyst layer approach and was calibrated to the experimental data by a least squares method. The behavior of important physical parameters as a function of I/C ratio and operating temperature were explored.

  16. Application of a Coated Film Catalyst Layer Model to a High Temperature Polymer Electrolyte Membrane Fuel Cell with Low Catalyst Loading Produced by Reactive Spray Deposition Technology

    OpenAIRE

    Myles, Timothy D.; Siwon Kim; Radenka Maric; Mustain, William E.

    2015-01-01

    In this study, a semi-empirical model is presented that correlates to previously obtained experimental overpotential data for a high temperature polymer electrolyte membrane fuel cell (HT-PEMFC). The goal is to reinforce the understanding of the performance of the cell from a modeling perspective. The HT-PEMFC membrane electrode assemblies (MEAs) were constructed utilizing an 85 wt. % phosphoric acid doped Advent TPS® membranes for the electrolyte and gas diffusion electrodes (GDEs) manufactu...

  17. High temperature polymer electrolyte membrane fuel cells

    DEFF Research Database (Denmark)

    This book is a comprehensive review of high-temperature polymer electrolyte membrane fuel cells (PEMFCs). PEMFCs are the preferred fuel cells for a variety of applications such as automobiles, cogeneration of heat and power units, emergency power and portable electronics. The first 5 chapters...... of the book describe rationalization and illustration of approaches to high temperature PEM systems. Chapters 6 - 13 are devoted to fabrication, optimization and characterization of phosphoric acid-doped polybenzimidazole membranes, the very first electrolyte system that has demonstrated the concept...... of and motivated extensive research activity in the field. The last 11 chapters summarize the state-of-the-art of technological development of high temperature-PEMFCs based on acid doped PBI membranes including catalysts, electrodes, MEAs, bipolar plates, modelling, stacking, diagnostics and applications....

  18. High Temperature Radio Frequency Loads

    CERN Document Server

    Federmann, S; Grudiev, A; Montesinos, E; Syratchev, I

    2011-01-01

    In the context of energy saving and recovery requirements the design of reliable and robust RF power loads which permit a high outlet temperature and high pressure of the cooling water is desirable. Cooling water arriving at the outlet withmore than 150 ◦C and high pressure has a higher value than water with 50 ◦C under low pressure. Conventional RF power loads containing dielectric and magnetic materials as well as sensitive ceramic windows usually do not permit going much higher than 90 ◦C. Here we present and discuss several design concepts for "metal only" RF high power loads. One concept is the application of magnetic steel corrugated waveguides near cutoff – this concept could find practical use above several GHz. Another solution are resonant structures made of steel to be installed in large waveguides for frequencies of 500 MHz or lower. Similar resonant structures above 100 MHz taking advantage of the rather high losses of normal steel may also be used in coaxial line geometries with large di...

  19. Faraday imaging at high temperatures

    Science.gov (United States)

    Hackel, Lloyd A.; Reichert, Patrick

    1997-01-01

    A Faraday filter rejects background light from self-luminous thermal objects, but transmits laser light at the passband wavelength, thus providing an ultra-narrow optical bandpass filter. The filter preserves images so a camera looking through a Faraday filter at a hot target illuminated by a laser will not see the thermal radiation but will see the laser radiation. Faraday filters are useful for monitoring or inspecting the uranium separator chamber in an atomic vapor laser isotope separation process. Other uses include viewing welds, furnaces, plasma jets, combustion chambers, and other high temperature objects. These filters are can be produced at many discrete wavelengths. A Faraday filter consists of a pair of crossed polarizers on either side of a heated vapor cell mounted inside a solenoid.

  20. High temperature control rod assembly

    Energy Technology Data Exchange (ETDEWEB)

    Vollman, Russell E. (Solana Beach, CA)

    1991-01-01

    A high temperature nuclear control rod assembly comprises a plurality of substantially cylindrical segments flexibly joined together in succession by ball joints. The segments are made of a high temperature graphite or carbon-carbon composite. The segment includes a hollow cylindrical sleeve which has an opening for receiving neutron-absorbing material in the form of pellets or compacted rings. The sleeve has a threaded sleeve bore and outer threaded surface. A cylindrical support post has a threaded shaft at one end which is threadably engaged with the sleeve bore to rigidly couple the support post to the sleeve. The other end of the post is formed with a ball portion. A hollow cylindrical collar has an inner threaded surface engageable with the outer threaded surface of the sleeve to rigidly couple the collar to the sleeve. the collar also has a socket portion which cooperates with the ball portion to flexibly connect segments together to form a ball and socket-type joint. In another embodiment, the segment comprises a support member which has a threaded shaft portion and a ball surface portion. The threaded shaft portion is engageable with an inner threaded surface of a ring for rigidly coupling the support member to the ring. The ring in turn has an outer surface at one end which is threadably engageably with a hollow cylindrical sleeve. The other end of the sleeve is formed with a socket portion for engagement with a ball portion of the support member. In yet another embodiment, a secondary rod is slidably inserted in a hollow channel through the center of the segment to provide additional strength. A method for controlling a nuclear reactor utilizing the control rod assembly is also included.

  1. New methods for modeling stream temperature using high resolution LiDAR, solar radiation analysis and flow accumulated values to predict stream temperature

    Science.gov (United States)

    In-stream temperature directly effects a variety of biotic organisms, communities and processes. Changes in stream temperature can render formally suitable habitat unsuitable for aquatic organisms, particularly native cold water species that are not able to adjust. In order to...

  2. Symmetry Non-restoration at High Temperature

    CERN Document Server

    Rius, N

    1998-01-01

    We discuss the (non)-restoration of global and local symmetries at high temperature. First, we analyze a two-scalar model with $Z_2 \\times Z_2$ symmetry using the exact renormalization group. We conclude that inverse symmetry breaking is possible in this kind of models within the perturbative regime. Regarding local symmetries, we consider the $SU(2) \\otimes U(1)$ gauge symmetry and focus on the case of a strongly interacting scalar sector. Employing a model-independent chiral Lagrangian we find indications of symmetry restoration.

  3. High temperature autoclave vacuum seals

    Science.gov (United States)

    Hoffman, J. R.; Simpson, W. G.; Walker, H. M.

    1971-01-01

    Aluminum sheet forms effective sealing film at temperatures up to 728 K. Soft aluminum wire rings provide positive seal between foil and platen. For applications at temperatures above aluminum's service temperature, stainless steel is used as film material and copper wire as sealant.

  4. Predicting High Temperature Dislocation Physics in HCP Crystal Structures

    Energy Technology Data Exchange (ETDEWEB)

    Hunter, Abigail [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Carpenter, John S. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Martinez Saez, Enrique [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2016-05-09

    This report applies models and experiments to answer key questions about the way materials deform; specifics regarding phase field dislocations dynamics; as well as high temperature rolling experiments.

  5. Critical Temperature Characteristics of Layered High-Temperature Superconductor Under Pressure

    Institute of Scientific and Technical Information of China (English)

    LIANG Fang-Ying

    2009-01-01

    We consider a Ginzburg-Landau modified model of layered high-temperature superconductor under pres-sure. We have theoretically studied the relation between the pressure and the temperature of layered high-temperature superconductor. If the pressure is not a constant, we have a relation of quadratic equation between the pressure and the temperature of layered high-temperature superconductor. In a special case, we find the critical temperature decreases with further increasing pressure. In another special case, the critical temperature increases with further increasing pressure.

  6. Finite element based stress analysis of graphite component in high temperature gas cooled reactor core using linear and nonlinear irradiation creep models

    Energy Technology Data Exchange (ETDEWEB)

    Mohanty, Subhasish, E-mail: smohanty@anl.gov; Majumdar, Saurindranath

    2015-10-15

    Highlights: • High temperature gas cooled reactor. • Finite element based stress analysis. • H-451 graphite. • Irradiation creep model. • Graphite reflector stress analysis. - Abstract: Irradiation creep plays a major role in the structural integrity of the graphite components in high temperature gas cooled reactors. Finite element procedures combined with a suitable irradiation creep model can be used to simulate the time-integrated structural integrity of complex shapes, such as the reactor core graphite reflector and fuel bricks. In the present work a comparative study was undertaken to understand the effect of linear and nonlinear irradiation creep on results of finite element based stress analysis. Numerical results were generated through finite element simulations of a typical graphite reflector.

  7. High-temperature thermocouples and related methods

    Science.gov (United States)

    Rempe, Joy L.; Knudson, Darrell L.; Condie, Keith G.; Wilkins, S. Curt

    2011-01-18

    A high-temperature thermocouple and methods for fabricating a thermocouple capable of long-term operation in high-temperature, hostile environments without significant signal degradation or shortened thermocouple lifetime due to heat induced brittleness.

  8. Formation of Glycidyl Fatty Acid Esters Both in Real Edible Oils during Laboratory-Scale Refining and in Chemical Model during High Temperature Exposure.

    Science.gov (United States)

    Cheng, Weiwei; Liu, Guoqin; Liu, Xinqi

    2016-07-27

    In the present study, the formation mechanisms of glycidyl fatty acid esters (GEs) were investigated both in real edible oils (soybean oil, camellia oil, and palm oil) during laboratory-scale preparation and refining and in chemical model (1,2-dipalmitin (DPG) and 1-monopalmitin (MPG)) during high temperature exposure (160-260 °C under nitrogen). The formation process of GEs in the chemical model was monitored using attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. The results showed that the roasting and pressing process could produce certain amounts of GEs that were much lower than that produced in the deodorization process. GE contents in edible oils increased continuously and significantly with increasing deodorization time below 200 °C. However, when the temperature exceeded 200 °C, GE contents sharply increased in 1-2 h followed by a gradual decrease, which could verify a simultaneous formation and degradation of GEs at high temperature. In addition, it was also found that the presence of acylglycerol (DAGs and MAGs) could significantly increase the formation yield of GEs both in real edible oils and in chemical model. Compared with DAGs, moreover, MAGs displayed a higher formation capacity but substantially lower contribution to GE formation due to their low contents in edible oils. In situ ATR-FTIR spectroscopic evidence showed that cyclic acyloxonium ion intermediate was formed during GE formation derived from DPG and MPG in chemical model heated at 200 °C.

  9. Furan Occurrence in Starchy Food Model Systems Processed at High Temperatures: Effect of Ascorbic Acid and Heating Conditions

    DEFF Research Database (Denmark)

    Mariotti, María; Granby, Kit; Fromberg, Arvid

    2012-01-01

    Furan, a potential carcinogen, has been detected in highly consumed starchy foods, such as bread and snacks; however, research on furan generation in these food matrixes has not been undertaken, thus far. The present study explored the effect of ascorbic acid addition and cooking methods (frying...... and baking) over furan occurrence and its relation with the non-enzymatic browning in a wheat flour starchy food model system. Results showed that furan generation significantly increased in the presence of ascorbic acid after 7 min of heating (p

  10. High Temperature Superconducting Underground Cable

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, Roger, A.

    2010-02-28

    The purpose of this Project was to design, build, install and demonstrate the technical feasibility of an underground high temperature superconducting (HTS) power cable installed between two utility substations. In the first phase two HTS cables, 320 m and 30 m in length, were constructed using 1st generation BSCCO wire. The two 34.5 kV, 800 Arms, 48 MVA sections were connected together using a superconducting joint in an underground vault. In the second phase the 30 m BSCCO cable was replaced by one constructed with 2nd generation YBCO wire. 2nd generation wire is needed for commercialization because of inherent cost and performance benefits. Primary objectives of the Project were to build and operate an HTS cable system which demonstrates significant progress towards commercial progress and addresses real world utility concerns such as installation, maintenance, reliability and compatibility with the existing grid. Four key technical areas addressed were the HTS cable and terminations (where the cable connects to the grid), cryogenic refrigeration system, underground cable-to-cable joint (needed for replacement of cable sections) and cost-effective 2nd generation HTS wire. This was the world’s first installation and operation of an HTS cable underground, between two utility substations as well as the first to demonstrate a cable-to-cable joint, remote monitoring system and 2nd generation HTS.

  11. High temperature power electronics for space

    Science.gov (United States)

    Hammoud, Ahmad N.; Baumann, Eric D.; Myers, Ira T.; Overton, Eric

    1991-01-01

    A high temperature electronics program at NASA Lewis Research Center focuses on dielectric and insulating materials research, development and testing of high temperature power components, and integration of the developed components and devices into a demonstrable 200 C power system, such as inverter. An overview of the program and a description of the in-house high temperature facilities along with experimental data obtained on high temperature materials are presented.

  12. Modelling room temperature ionic liquids.

    Science.gov (United States)

    Bhargava, B L; Balasubramanian, Sundaram; Klein, Michael L

    2008-08-07

    Room temperature ionic liquids (IL) composed of organic cations and inorganic anions are already being utilized for wide-ranging applications in chemistry. Complementary to experiments, computational modelling has provided reliable details into the nature of their interactions. The intra- and intermolecular structures, dynamic and transport behaviour and morphologies of these novel liquids have also been explored using simulations. The current status of molecular modelling studies is presented along with the prognosis for future work in this area.

  13. Modelling water temperature in TOXSWA

    NARCIS (Netherlands)

    Jacobs, C.M.J.; Deneer, J.W.; Adriaanse, P.I.

    2010-01-01

    A reasonably accurate estimate of the water temperature is necessary for a good description of the degradation of plant protection products in water which is used in the surface water model TOXSWA. Based on a consideration of basic physical processes that describe the influence of weather on the

  14. A comparative study on improved Arrhenius-type and artificial neural network models to predict high-temperature flow behaviors in 20MnNiMo alloy.

    Science.gov (United States)

    Quan, Guo-zheng; Yu, Chun-tang; Liu, Ying-ying; Xia, Yu-feng

    2014-01-01

    The stress-strain data of 20MnNiMo alloy were collected from a series of hot compressions on Gleeble-1500 thermal-mechanical simulator in the temperature range of 1173 ∼ 1473 K and strain rate range of 0.01 ∼ 10 s(-1). Based on the experimental data, the improved Arrhenius-type constitutive model and the artificial neural network (ANN) model were established to predict the high temperature flow stress of as-cast 20MnNiMo alloy. The accuracy and reliability of the improved Arrhenius-type model and the trained ANN model were further evaluated in terms of the correlation coefficient (R), the average absolute relative error (AARE), and the relative error (η). For the former, R and AARE were found to be 0.9954 and 5.26%, respectively, while, for the latter, 0.9997 and 1.02%, respectively. The relative errors (η) of the improved Arrhenius-type model and the ANN model were, respectively, in the range of -39.99% ∼ 35.05% and -3.77% ∼ 16.74%. As for the former, only 16.3% of the test data set possesses η-values within ± 1%, while, as for the latter, more than 79% possesses. The results indicate that the ANN model presents a higher predictable ability than the improved Arrhenius-type constitutive model.

  15. High Temperature Chemistry at NASA: Hot Topics

    Science.gov (United States)

    Jacobson, Nathan S.

    2014-01-01

    High Temperature issues in aircraft engines Hot section: Ni and Co based Superalloys Oxidation and Corrosion (Durability) at high temperatures. Thermal protection system (TPS) and RCC (Reinforced Carbon-Carbon) on the Space Shuttle Orbiter. High temperatures in other worlds: Planets close to their stars.

  16. High temperature vapors science and technology

    CERN Document Server

    Hastie, John

    2012-01-01

    High Temperature Vapors: Science and Technology focuses on the relationship of the basic science of high-temperature vapors to some areas of discernible practical importance in modern science and technology. The major high-temperature problem areas selected for discussion include chemical vapor transport and deposition; the vapor phase aspects of corrosion, combustion, and energy systems; and extraterrestrial high-temperature species. This book is comprised of seven chapters and begins with an introduction to the nature of the high-temperature vapor state, the scope and literature of high-temp

  17. High temperature quark localization by Polyakov loops

    CERN Document Server

    Kovacs, Tamas G; Bruckmann, Falk; Schierenberg, Sebastian

    2011-01-01

    We study the low eigenmodes of the overlap and staggered Dirac operator at high temperature. We show that the recently found localized quark modes obeying Poisson statistics are connected to physical gauge field objects with their size and density scaling in the continuum limit. The localized modes are also strongly correlated with large fluctuations of the Polyakov loop. Based on that we construct a random matrix model of the low Dirac modes inspired by dimensional reduction. Our model reproduces the Poisson to random matrix transition seen in the lattice Dirac spectrum.

  18. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network.

    Science.gov (United States)

    Shakiba, Mohammad; Parson, Nick; Chen, X-Grant

    2016-06-30

    The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002-0.31 wt %) was investigated by uniaxial compression tests conducted at different temperatures (400 °C-550 °C) and strain rates (0.01-10 s(-1)). The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN) model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  19. Modeling the Effects of Cu Content and Deformation Variables on the High-Temperature Flow Behavior of Dilute Al-Fe-Si Alloys Using an Artificial Neural Network

    Directory of Open Access Journals (Sweden)

    Mohammad Shakiba

    2016-06-01

    Full Text Available The hot deformation behavior of Al-0.12Fe-0.1Si alloys with varied amounts of Cu (0.002–0.31 wt % was investigated by uniaxial compression tests conducted at different temperatures (400 °C–550 °C and strain rates (0.01–10 s−1. The results demonstrated that flow stress decreased with increasing deformation temperature and decreasing strain rate, while flow stress increased with increasing Cu content for all deformation conditions studied due to the solute drag effect. Based on the experimental data, an artificial neural network (ANN model was developed to study the relationship between chemical composition, deformation variables and high-temperature flow behavior. A three-layer feed-forward back-propagation artificial neural network with 20 neurons in a hidden layer was established in this study. The input parameters were Cu content, temperature, strain rate and strain, while the flow stress was the output. The performance of the proposed model was evaluated using the K-fold cross-validation method. The results showed excellent generalization capability of the developed model. Sensitivity analysis indicated that the strain rate is the most important parameter, while the Cu content exhibited a modest but significant influence on the flow stress.

  20. New methods for modeling stream temperature using high resolution LiDAR, solar radiation analysis and flow accumulated values

    Science.gov (United States)

    In-stream temperature directly effects a variety of biotic organisms, communities and processes. Changes in stream temperature can render formally suitable habitat unsuitable for aquatic organisms, particularly native cold water species that are not able to adjust. In order to an...

  1. Numerical model of a thermoelectric generator with compact plate-fin heat exchanger for high temperature PEM fuel cell exhaust heat recovery

    DEFF Research Database (Denmark)

    Xin, Gao; Andreasen, Søren Juhl; Chen, Min

    2012-01-01

    This paper presents a numerical model of an exhaust heat recovery system for a high temperature polymer electrolyte membrane fuel cell (HTPEMFC) stack. The system is designed as thermoelectric generators (TEGs) sandwiched in the walls of a compact plate-fin heat exchanger. Its model is based...... plate-fin heat exchangers is adopted. Then the model is validated against experimental data and the main variables are identified by means of a sensitivity analysis. Finally, the system configuration is optimized for recovering heat from the exhaust gas. The results exhibit the crucial importance...... on a finite-element approach. On each discretized segment, fluid properties, heat transfer process and TEG performance are locally calculated for higher model precision. To benefit both the system design and fabrication, the way to model TEG modules is herein reconsidered; a database of commercialized compact...

  2. Model for the high-temperature oxygen-ordering thermodynamics in YBa2Cu3O6+x - inclusion of electron spin and charge degrees of freedom

    DEFF Research Database (Denmark)

    Schleger, P.; Hardy, W.N.; Casalta, H.

    1994-01-01

    A lattice-gas model for the high temperature oxygen-ordering thermodynamics in YBa2Cu3O6+x is presented, which assumes constant effective pair interactions between oxygen atoms and includes in a simple fashion the effect of the electron spin and charge degrees of freedom. This is done using...... a commonly utilized picture relating the creation of mobile electron holes and unpaired spins to the insertion of oxygen into the basal plane. The model is solved using the nearest-neighbor square approximation of the cluster-variation method. In addition, preliminary Monte Carlo results using next...

  3. HIGH TEMPERATURE TIME DEPENDENT UNIAXIAL AND MULTIAXIAL FATIGUE DAMAGE MODEL%高温时间相关单多轴疲劳损伤模型

    Institute of Scientific and Technical Information of China (English)

    孙国芹; 尚德广; 李承山

    2009-01-01

    针对高温疲劳中蠕变和氧化因素的影响,提出高温循环加载下时间相关疲劳损伤模型.根据材料高温疲劳微观观察和疲劳过程,充分考虑拉压应变率和循环周期不同而造成的不同损伤,提出高温影响折算时间的计算方法.结合损伤理论和高温对疲劳损伤的影响,把无保载时间的高温疲劳损伤分为纯疲劳损伤、时间相关损伤和交互损伤,损伤模型经高温2.25Cr-1Mo钢单多轴疲劳试验验证,结果表明,误差在两个因子之内.%Time dependent fatigue damage model under cyclic loading was proposed by considering the effect of creep and oxidation at high temperature on the fatigue damage. The high temperature fatigue damage without holding time was divided into pure fatigue damage, damage caused by the time dependent factors and interactive damage to combine effect of high temperature to fatigue damage with the damage rule. The converting time influenced by high temperature was proposed according to tension-compression strain rate and different cycle period based on the SEM(scanning electron microscope) observation of the fatigue rupture surface and fatigue process. The results for 2.25Cr-1Mo steel tests under uniaxial and multiaxial high temperature fatigue showed an error within a factor of two.

  4. Three-dimensional model of a 50 cm{sup 2} high temperature PEM fuel cell. Study of the flow channel geometry influence

    Energy Technology Data Exchange (ETDEWEB)

    Lobato, Justo; Canizares, Pablo; Rodrigo, Manuel A.; Pinar, F. Javier; Mena, Esperanza; Ubeda, Diego [Chemical Enginnering Department, University of Castilla-La Mancha. Enrique Costa Novella Building, Avda. Camilo Jose Cela, n 12, 13071, Ciudad Real (Spain)

    2010-06-15

    In this work, a three-dimensional half-cell model for a 50 cm{sup 2} high temperature polyelectrolyte membrane fuel cell (HTPEMFC) has been implemented in a Computational Fluid Dynamics (CFD) application. It was solved for three different flow channel geometries: 4-step serpentine, parallel and pin-type. Each geometry leads to a very well defined current density profile which indicates that current density distribution is directly linked to the way reactants are spread over the electrode surface. The model predicts that parallel flow channels present a significant lower performance probably due to the existence of preferential paths which makes the reactant gases not to be well distributed over the whole electrode surface. This results in lower output current densities when this geometry is used, especially at high oxygen demand conditions. This behavior was also detected by experimental measurement. Serpentine and pin-type flow channels were found to perform very similarly, although slightly higher limit current densities are predicted when using serpentine geometry. Inlet flow rate as well as temperature influence were also studied. The model predicts mass transfer problems and low limit current densities when the fuel cell is fed with small oxygen flow rates, whereas no differences regarding average flow rates are noticed if it is over increased. Better fuel cell performance is predicted while temperature grows as it could be expected. (author)

  5. The Effect of Temperature and Increased Rainfall on Carbon Dioxide Exchange in a High Arctic Ecosystem: Improving Models and Testing Linearity of Response

    Science.gov (United States)

    Steltzer, H.; Welker, J.; Sullivan, P.

    2006-12-01

    Ecosystem carbon dioxide exchange determines the terrestrial flux of carbon dioxide to the atmosphere through the two component processes of photosynthesis and respiration. Temperature and water availability are dominant factors that regulate carbon dioxide exchange and ecosystem productivity across the globe. Yet, in many ecosystems, the complex interaction of temperature and water availability and their individual and combined effects on photosynthesis and respiration make it difficult to predict how climate change will affect carbon dioxide exchange. For example, climate warming can increase carbon dioxide uptake in wetter Arctic ecosystems, but leads to the loss of carbon dioxide to the atmosphere in drier Arctic ecosystems. Characterizing how temperature and water availability affect ecosystem carbon exchange in the Arctic is essential to determine whether the rate of climate warming could accelerate due to carbon dioxide losses from Arctic ecosystems. We conducted a multi-level warming experiment that included control plots and two- levels of warming in a widespread High Arctic ecosystem. Infrared lamps were used to warm the tundra during the growing season and rainfall was increased by 50 percent in control plots and the higher level warming treatment. Carbon dioxide exchange was measured using chamber techniques over several 24-hour periods during the growing season for three years and was resolved into the component fluxes. Climate and biophysical variables that affect carbon dioxide exchange rates were measured in coordination with these flux measurements. We chose to analyze the data from this experiment by fitting the data to light and temperature response functions for gross ecosystem photosynthesis and ecosystem respiration, respectively. Based on our sample size of 30 experimental plots (5 treatments x 6 replicates), we selected relatively simple models of carbon dioxide exchange to minimize overfitting, but considered linear and nonlinear models

  6. High temperature superconductors for magnetic suspension applications

    Science.gov (United States)

    Mcmichael, C. K.; Cooley, R. S.; Chen, Q. Y.; Ma, K. B.; Lamb, M. A.; Meng, R. L.; Chu, C. W.; Chu, W. K.

    1994-01-01

    High temperature superconductors (HTS) hold the promise for applications in magnetic levitation bearings, vibration damping, and torque coupling. Traditional magnetic suspension systems require active feedback and vibration controls in which power consumption and low frequency vibration are among the major engineering concerns. HTS materials have been demonstrated to be an enabling approach towards such problems due to their flux trapping properties. In our laboratory at TCSUH, we have been conducting a series of experiments to explore various mechanical applications using HTS. We have constructed a 30 lb. model flywheel levitated by a hybrid superconducting magnetic bearing (HSMB). We are also developing a levitated and vibration-dampled platform for high precision instrumentation. These applications would be ideal for space usages where ambient temperature is adequate for HTS to operate properly under greatly reduced cryogenic requirements. We will give a general overview of these potential applications and discuss the operating principles of the HTS devices we have developed.

  7. Fast pyrolysis of biomass at high temperatures

    DEFF Research Database (Denmark)

    Trubetskaya, Anna

    This Ph.D. thesis describes experimental and modeling investigations of fast high temperature pyrolysis of biomass. Suspension firing of biomass is widely used for power generation and has been considered as an important step in reduction of greenhouse gas emissions by using less fossil fuels. Fast...... pyrolysis at high temperatures plays a significant role in the overall combustion process since the biomass type, the reaction kinetics and heat transfer rates during pyrolysis influence the volatile gas release. The solid residue yield and its properties in suspension firing, including particle size...... and shape, composition, reactivity and burnout depend significantly on the operating conditions of the fast pyrolysis. Biomass fast pyrolysis experiments were performed in a laboratory-scale wire mesh reactor and bench scale atmospheric pressure drop tube / entrained flow reactors with the aim...

  8. Critical parameters and universal amplitude ratios of two-dimensional spin-S Ising models using high- and low-temperature expansions

    CERN Document Server

    Butera, P

    2003-01-01

    For the study of Ising models of general spin S on the square lattice, we have combined our recently extended high-temperature expansions with the low-temperature expansions derived some time ago by Enting, Guttmann and Jensen. We have computed for the first time various critical parameters and improved the estimates of others. Moreover the properties of hyperscaling and of universality (spin S independence) of exponents and of various dimensionless amplitude combinations have been verified accurately. Assuming the validity of the lattice-lattice scaling, from our estimates of critical amplitudes for the square lattice we have also obtained estimates of the corresponding amplitudes for the spin S Ising model on the triangular, honeycomb, and kagome` lattices.

  9. High temperature measurement of water vapor absorption

    Science.gov (United States)

    Keefer, Dennis; Lewis, J. W. L.; Eskridge, Richard

    1985-01-01

    An investigation was undertaken to measure the absorption coefficient, at a wavelength of 10.6 microns, for mixtures of water vapor and a diluent gas at high temperature and pressure. The experimental concept was to create the desired conditions of temperature and pressure in a laser absorption wave, similar to that which would be created in a laser propulsion system. A simplified numerical model was developed to predict the characteristics of the absorption wave and to estimate the laser intensity threshold for initiation. A non-intrusive method for temperature measurement utilizing optical laser-beam deflection (OLD) and optical spark breakdown produced by an excimer laser, was thoroughly investigated and found suitable for the non-equilibrium conditions expected in the wave. Experiments were performed to verify the temperature measurement technique, to screen possible materials for surface initiation of the laser absorption wave and to attempt to initiate an absorption wave using the 1.5 kW carbon dioxide laser. The OLD technique was proven for air and for argon, but spark breakdown could not be produced in helium. It was not possible to initiate a laser absorption wave in mixtures of water and helium or water and argon using the 1.5 kW laser, a result which was consistent with the model prediction.

  10. High temperature inorganic membranes for separating hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1995-08-01

    Effort has continued to accumulate data on the transport of gases over the temperature range from room temperature to 275{degrees}C with inorganic membranes having a range of pore radii from approximately 0.25 nm to 3 mn. An experimental alumina membrane having an estimated mean pore radius of 0.25 nm has been fabricated and tested. Extensive testing of this membrane indicated that the separation factor for helium and carbon tetrafluoride at 250{degrees}C was 59 and the extrapolated high temperature separation factor was 1,193. For safety reasons, earlier flow measurements concentrated on helium, carbon dioxide, and carbon tetrafluoride. New data have been acquired with hydrogen to verify the agreement with the other gases. During the measurements with hydrogen, it was noted that a considerable amount of moisture was present in the test gas. The source of this moisture and its effect on permeance was examined. Improvements were implemented to the flow test system to minimize the water content of the hydrogen test gas, and subsequent flow measurements have shown excellent results with hydrogen. The extrapolation of separation factors as a function of temperature continues to show promise as a means of using the hard sphere model to determine the pore size of membranes. The temperature dependence of helium transport through membranes appears to be considerably greater than other gases for the smallest pore sizes. The effort to extend temperature dependence to the hard sphere model continues to be delayed, primarily because of a lack of adequate adsorption data.

  11. Thermodynamics of High Temperature Plasmas

    Directory of Open Access Journals (Sweden)

    Ettore Minardi

    2009-03-01

    Full Text Available In this work we discuss how and to what extent the thermodynamic concepts and the thermodynamic formalism can be extended to the description of high temperature states of the plasma not necessarily associated with a Boltzmann distribution and with thermal equilibrium.The discussion is based on the “magnetic or electrostatic entropy concept”, an interpretative and predictive tool based on probability and information, defined in a suitably coarse-grained possibility space of all current density or of all electric charge density distributions under testable constraints, and whose variation properties are proven to be related under certain conditions to the equilibrium and the stability of the system. In the case of magnetic equilibrium the potentiality of the magnetic entropy concept is illustrated by comparing the predictions of the current density and pressure profiles with the observations in different tokamak machines and different tokamak regimes, as well as by showing how the equilibrium and the stability in devices as different as the reversed field pinch or the magnetic well are described by the variation properties of the same entropy functional applied to the different situations. In fact it emerges that the maximum of the entropy can be seen in these different cases as an optimization constraint for the minimum of the magnetic energy. The application of the entropy concept to the electrostatic processes shows in particular that the so-called reactive instabilities (non-dissipative, non-resonant instabilities with a marginal point admit a neighboring state with higher entropy and are therefore of special relevance from the point of view of the physical evolution of the system. In this case the thermodynamic formalism allows the introduction of the concept of “thermodynamic fluctuations” of the macroscopic charge density and provides a method for the calculation of the “thermodynamic” fluctuation levels both on the stable as

  12. Diamond based detectors for high temperature, high radiation environments

    Science.gov (United States)

    Metcalfe, A.; Fern, G. R.; Hobson, P. R.; Smith, D. R.; Lefeuvre, G.; Saenger, R.

    2017-01-01

    Single crystal CVD diamond has many desirable properties as a radiation detector; exceptional radiation hardness and physical hardness, chemical inertness, low Z (close to human tissue, good for dosimetry and transmission mode applications), wide bandgap (high temperature operation with low noise and solar blind), an intrinsic pathway to fast neutron detection through the 12C(n,α)9Be reaction. This combination of radiation hardness, temperature tolerance and ability to detect mixed radiation types with a single sensor makes diamond particularly attractive as a detector material for harsh environments such as nuclear power station monitoring (fission and fusion) and oil well logging. Effective exploitation of these properties requires the development of a metallisation scheme to give contacts that remain stable over extended periods at elevated temperatures (up to 250°C in this instance). Due to the cost of the primary detector material, computational modelling is essential to best utilise the available processing methods for optimising sensor response through geometry and conversion media configurations and to fully interpret experimental data. Monte Carlo simulations of our diamond based sensor have been developed, using MCNP6 and FLUKA2011, assessing the sensor performance in terms of spectral response and overall efficiency as a function of the detector and converter geometry. Sensors with varying metallisation schemes for high temperature operation have been fabricated at Brunel University London and by Micron Semiconductor Limited. These sensors have been tested under a varied set of conditions including irradiation with fast neutrons and alpha particles at high temperatures. The presented study indicates that viable metallisation schemes for high temperature contacts have been successfully developed and the modelling results, supported by preliminary experimental data from partners, indicate that the simulations provide a reasonable representation of

  13. High temperature superconducting fault current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Hull, John R. (Hinsdale, IL)

    1997-01-01

    A fault current limiter (10) for an electrical circuit (14). The fault current limiter (10) includes a high temperature superconductor (12) in the electrical circuit (14). The high temperature superconductor (12) is cooled below its critical temperature to maintain the superconducting electrical properties during operation as the fault current limiter (10).

  14. (Krauss) at constant high temperatures

    African Journals Online (AJOL)

    the various physical and chemical factors that may affect freshwater snails. However ... order to assess the effect of temperature on the organism, it is essential to ..... of snails by parasites is of cardinal importance to shed light on the population ...

  15. Deep Trek High Temperature Electronics Project

    Energy Technology Data Exchange (ETDEWEB)

    Bruce Ohme

    2007-07-31

    This report summarizes technical progress achieved during the cooperative research agreement between Honeywell and U.S. Department of Energy to develop high-temperature electronics. Objects of this development included Silicon-on-Insulator (SOI) wafer process development for high temperature, supporting design tools and libraries, and high temperature integrated circuit component development including FPGA, EEPROM, high-resolution A-to-D converter, and a precision amplifier.

  16. Damage evolution of metallic materials during high temperature plastic deformation

    Institute of Scientific and Technical Information of China (English)

    汪凌云; 刘雪峰; 汤爱涛; 黄光杰

    2002-01-01

    The damage evolution of high temperature plastic deformation of metallic materials was studied by use of continuum damage mechanics (CDM) theory. Based on thermodynamics, on a damage variable D and Zener-Hollomon parameter Z, and on the effective stress concept, a damage evolution model of high temperature plastic deformation was derived and was used to analyze the damage evolution of 1420 Al-Li alloy during high temperature plastic deformation. The model that is verified by tests can also be applied to the materials that are loaded prorata or out of proportion during high temperature plastic deformation. It extends the applied scope of damage mechanics.

  17. Mathematical Modeling of High-Temperature Constitutive Equations and Hot Processing Maps for As-Cast SA508-3 Steel

    Science.gov (United States)

    Sui, Dashan; Wang, Tao; Zhu, Lingling; Gao, Liang; Cui, Zhenshan

    2016-08-01

    The hot deformation behavior and hot workability characteristics of as-cast SA508-3 steel were studied by modeling the constitutive equations and developing hot processing maps. The isothermal compression experiments were carried out at temperatures of 950°C, 1050°C, 1150°C, and 1250°C and strain rates of 0.001 s-1, 0.01 s-1, 0.1 s-1, and 1 s-1 respectively. The two-stage flow stress models were established through the classical theories on work hardening and softening, and the solution of activation energy for hot deformation was 355.0 kJ mol-1 K-1. Based on the dynamic material model, the power dissipation and instability maps were developed separately at strains of 0.2, 0.4, 0.6 and 0.8. The power dissipation rate increases with both the increase of temperature and the decrease of strain rate, and the instable region mainly appears on the conditions of low temperature and high strain rate. The optimal hot working parameters for as-cast SA508-3 steel are 1050-1200°C/0.001-0.1 s-1, with about 25-40% peak efficiency of power dissipation.

  18. Current trends in high temperature design

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, D.L. (Illinois Univ., Urbana, IL (United States). Dept. of Mechanical Engineering)

    1992-01-01

    A review of high temperature design guidelines has been carried out in preparation for designing a solar storage module for the Freedom Spacelab. Three major guidelines, N47, R5 and RCC-MR form the basis of the survey. The main issues with current, mature design in the power industry appear to be adequately covered by these guidelines. A significant finding is that long established models of material damage have survived the test of time very well. A new design regime referred to as Very High Temperature Design (VHTD) is identified. The characteristics of this regime are changing material properties which require some changes in philosophy in drafting of future codes, particularly in regard to definitions of yield strengths and other design allowables. Finally, there is some discussion of the more general use of the stress/strain plane, e.g. isochronous curves, for representation of very complex material constitutive behaviour. A concept called the 'Relaxation Locus', which summarizes essential local constrained component behavior, is introduced and its application to high temperature design problems is discussed briefly. (author).

  19. Concentration and mobility of charge carriers in thin polymers at high temperature determined by electrode polarization modeling

    Science.gov (United States)

    Diaham, Sombel; Locatelli, Marie-Laure

    2012-07-01

    Charge carrier concentration (n0) and effective mobility (μeff) are reported in two polymer films (dielectric spectroscopy data. It is shown that the glass transition temperature (Tg) occurrence has a strong influence on the temperature dependence of n0 and μeff. We carry out that n0 presents two distinct Arrhenius-like behaviors below and above Tg, while μeff exhibits a Vogel-Fulcher-Tamman behavior only above Tg whatever the polymer under study. For polyimide films, n0 varies from 1 × 1014 to 4 × 1016 cm-3 and μeff from 1 × 10-8 to 2 × 10-6 cm2 V-1 s-1 between 200 °C to 400 °C. Poly(amide-imide) films show n0 values between 6 × 1016 and 4 × 1018 cm-3 from 270 °C to 400 °C, while μeff varies between 1 × 10-10 and 2 × 10-7 cm2 V-1 s-1. Considering the activation energies of these physical parameters in the temperature range of investigation, n0 and μeff values appear as coherent with those reported in the literature at lower temperature (Polyimide films appear as good candidates due to nS values less than 1011 cm-2 up to 300 °C.

  20. Two-particle excitations in the Hubbard model for high-temperature superconductors. A quantum cluster study

    Energy Technology Data Exchange (ETDEWEB)

    Brehm, Sascha

    2009-02-26

    Two-particle excitations, such as spin and charge excitations, play a key role in high-T{sub c} cuprate superconductors (HTSC). Due to the antiferromagnetism of the parent compound the magnetic excitations are supposed to be directly related to the mechanism of superconductivity. In particular, the so-called resonance mode is a promising candidate for the pairing glue, a bosonic excitation mediating the electronic pairing. In addition, its interactions with itinerant electrons may be responsible for some of the observed properties of HTSC. Hence, getting to the bottom of the resonance mode is crucial for a deeper understanding of the cuprate materials. To analyze the corresponding two-particle correlation functions we develop in the present thesis a new, non-perturbative and parameter-free technique for T=0 which is based on the Variational Cluster Approach (VCA, an embedded cluster method for one-particle Green's functions). Guided by the spirit of the VCA we extract an effective electron-hole vertex from an isolated cluster and use a fully renormalized bubble susceptibility {chi}{sub 0} including the VCA one-particle propagators. Within our new approach, the magnetic excitations of HTSC are shown to be reproduced for the Hubbard model within the relevant strong-coupling regime. Exceptionally, the famous resonance mode occurring in the underdoped regime within the superconductivity-induced gap of spin-flip electron-hole excitations is obtained. Its intensity and hourglass dispersion are in good overall agreement with experiments. Furthermore, characteristic features such as the position in energy of the resonance mode and the difference of the imaginary part of the susceptibility in the superconducting and the normal states are in accord with Inelastic Neutron Scattering (INS) experiments. For the first time, a strongly-correlated parameter-free calculation revealed these salient magnetic properties supporting the S=1 magnetic exciton scenario for the

  1. High Temperature and Pressure Alkaline Electrolysis

    DEFF Research Database (Denmark)

    Allebrod, Frank

    and oxygen with a new type of alkaline electrolysis cell at high temperatures and pressures. To perform measurements under high pressure and at elevated temperatures it was necessary to build a measurement system around an autoclave which could stand high temperatures up to 250 °C and pressures up to 200 bar...... as well as extremely caustic environments. Based on a literature study to identify resistant materials for these conditions, Inconel 600 was selected among the metals which are available for autoclave construction. An initial single atmosphere high temperature and pressure measurement setup was build...... comprising this autoclave. A second high temperature and pressure measurement setup was build based on experiences from the first setup in order to perform automatized measurements. The conductivity of aqueous KOH at elevated temperatures and high concentrations was investigated using the van der Pauw method...

  2. A comparison of general circulation models and their application to temperature change assessments in a high-latitude agricultural area in northeastern China

    Science.gov (United States)

    Ouyang, Wei; Shi, Yandan; Hao, Fanghua; Jiao, Wei

    2016-07-01

    The two main focuses of this study are a comparison of the general circulation models (GCMs) from Phase 5 of the Coupled Model Inter-Comparison Project (CMIP5) and an assessment of the surface air temperature under multiple climate scenarios in a high middle latitude area of China. In the past 55 years temperatures in this area have shown an obvious upward trend (a rise of 1.50 °C), and another important change during this time period was a significant alteration in tillage practices that occurred in 1986. Using methods and tools such as average deviation, the Taylor figure and the space techniques rating (SS), time sequence related coefficient, and the M2 index, a comprehensive spatial-temporal assessment was performed based on the CMIP5 models. The simulations provided by the models had certain common features, but there were also significant differences. The three best models (CanCM4, INMCM4, and IPSL-CM5A-MR) have a common characteristic: the institutions where they were developed are located at latitudes that are similar to or higher than the latitude of the study area. Future climate changes were analyzed by simulating a representative concentration pathway 4.5/8.5 (RCP4.5/RCP8.5) of emission scenarios with a multi-model ensemble. The temperatures under the RCP4.5 and RCP8.5 scenarios have a certain upward trend, with increases of 2.24 and 5.44 °C, respectively. From a spatial perspective, the distributions of the temperature change trend showed a southwest to northeast step increase under both scenarios, but the warming trend in the area of each lattice point under the RCP4.5 scenario is much lower than that of the RCP8.5 scenario. There are no obvious changes in the spatial distribution of the accumulated intensity and frequency of the regional air temperature in the three periods (2016-2035, 2036-2065, and 2066-2095) under the two scenarios.

  3. High-temperature protective coatings on superalloys

    Institute of Scientific and Technical Information of China (English)

    刘培生; 梁开明; 周宏余

    2002-01-01

    Protective coatings are essential for superalloys to serve as blades of gas turb ines at high temperatures, and they primarily include aluminide coating, MCrAlY overlay coating, thermal barrier coating and microcrystalline coating. In this paper, all these high-temperature coatings are reviewed as well as their preparing techniques. Based on the most application and the main failure way, the importance is then presented for further deepgoing study on the high-temperature oxidation law of aluminide coatings.

  4. High-density genetic map and identification of QTLs for responses to temperature and salinity stresses in the model brown alga Ectocarpus

    Science.gov (United States)

    Avia, Komlan; Coelho, Susana M.; Montecinos, Gabriel J.; Cormier, Alexandre; Lerck, Fiona; Mauger, Stéphane; Faugeron, Sylvain; Valero, Myriam; Cock, J. Mark; Boudry, Pierre

    2017-01-01

    Deciphering the genetic architecture of adaptation of brown algae to environmental stresses such as temperature and salinity is of evolutionary as well as of practical interest. The filamentous brown alga Ectocarpus sp. is a model for the brown algae and its genome has been sequenced. As sessile organisms, brown algae need to be capable of resisting the various abiotic stressors that act in the intertidal zone (e.g. osmotic pressure, temperature, salinity, UV radiation) and previous studies have shown that an important proportion of the expressed genes is regulated in response to hyposaline, hypersaline or oxidative stress conditions. Using the double digest RAD sequencing method, we constructed a dense genetic map with 3,588 SNP markers and identified 39 QTLs for growth-related traits and their plasticity under different temperature and salinity conditions (tolerance to high temperature and low salinity). GO enrichment tests within QTL intervals highlighted membrane transport processes such as ion transporters. Our study represents a significant step towards deciphering the genetic basis of adaptation of Ectocarpus sp. to stress conditions and provides a substantial resource to the increasing list of tools generated for the species. PMID:28256542

  5. High Temperature Heterojunction Bipolar Transistors

    Science.gov (United States)

    1994-04-15

    2700 cmW/V-s at room temperature, a far higher value than ever found for GaN or AlGaN. Thus a GaN/ InGaN HEMT would be analogous to InP/InGaAs HEMTs...Spire’s ECR plasma source modif led as a crystal growth reactor. 8 The substrate for the film deposition is mounted on a sample holder which is...The three samples from the second growth run were also characterized. One sample was found to have a very even frosty white haze on it. The other

  6. A high temperature fuel element

    Energy Technology Data Exchange (ETDEWEB)

    Sekido, A.; Nakai, M.; Ninomiya, Y.

    1982-12-21

    A solid electrolyte which conducts electricity with heating by oxygen ions and operates at a temperature of 1,000C is used in the element. The cathode, besides the ionic conductivity in oxygen, has an electron conductivity. The anode has electron conductivity. Substances such as Bi203, into which oxides of alkaline earth metals are added, are used for making the cathode. The electrolyte consists of ZrO2 and Y2O3, to which CaO is added. WC, to which an H2 type fuel is fed, serves as the anode. The element has a long service life.

  7. Ultrasonic Sensors for High Temperature Applications

    Science.gov (United States)

    Tittmann, Bernhard; Aslan, Mustafa

    1999-05-01

    Many processes take place under conditions other than ambient, and chief among these is high temperature. Examples of high temperature industrial processes are resin transfer molding, molten metal infiltration and rheocasting of composite metals alloys. The interaction of waves with viscous fluids is an additional complication adding to an already complicated problem of operating a sensor at high temperature for extended periods of time. This report attempts to provide an insight into the current state of the art of sensor techniques for in-situ high temperature monitoring.

  8. Advances in high temperature chemistry 1

    CERN Document Server

    Eyring, Leroy

    2013-01-01

    Advances in High Temperature Chemistry, Volume 1 describes the complexities and special and changing characteristics of high temperature chemistry. After providing a brief definition of high temperature chemistry, this nine-chapter book goes on describing the experiments and calculations of diatomic transition metal molecules, as well as the advances in applied wave mechanics that may contribute to an understanding of the bonding, structure, and spectra of the molecules of high temperature interest. The next chapter provides a summary of gaseous ternary compounds of the alkali metals used in

  9. High Temperature Capacitors for Venus Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — In this SBIR program, TRS Technologies has developed several new dielectrics for high temperature applications including signal conditioning, filtering and energy...

  10. High temperature phase equilibria and phase diagrams

    CERN Document Server

    Kuo, Chu-Kun; Yan, Dong-Sheng

    2013-01-01

    High temperature phase equilibria studies play an increasingly important role in materials science and engineering. It is especially significant in the research into the properties of the material and the ways in which they can be improved. This is achieved by observing equilibrium and by examining the phase relationships at high temperature. The study of high temperature phase diagrams of nonmetallic systems began in the early 1900s when silica and mineral systems containing silica were focussed upon. Since then technical ceramics emerged and more emphasis has been placed on high temperature

  11. Alloys developed for high temperature applications

    Science.gov (United States)

    Basuki, Eddy Agus; Prajitno, Djoko Hadi; Muhammad, Fadhli

    2017-01-01

    Alloys used for high temperatures applications require combinations of mechanical strength, microstructural stability and corrosion/oxidation resistance. Nickel base superalloys have been traditionally the prime materials utilized for hot section components of aircraft turbine engines. Nevertheless, due to their limited melting temperatures, alloys based on intermetallic compounds, such as TiAl base alloys, have emerged as high temperature materials and intensively developed with the main aim to replace nickel based superalloys. For applications in steam power plants operated at lower temperatures, ferritic high temperature alloys still attract high attention, and therefore, development of these alloys is in progress. This paper highlights the important metallurgical parameters of high temperature alloys and describes few efforts in the development of Fe-Ni-Al based alloys containing B2-(Fe,Ni)Al precipitates, oxide dispersion strengthening (ODS) ferritic steels and titanium aluminide based alloys include important protection system of aluminide coatings.

  12. Investigations into High Temperature Components and Packaging

    Energy Technology Data Exchange (ETDEWEB)

    Marlino, L.D.; Seiber, L.E.; Scudiere, M.B.; M.S. Chinthavali, M.S.; McCluskey, F.P.

    2007-12-31

    The purpose of this report is to document the work that was performed at the Oak Ridge National Laboratory (ORNL) in support of the development of high temperature power electronics and components with monies remaining from the Semikron High Temperature Inverter Project managed by the National Energy Technology Laboratory (NETL). High temperature electronic components are needed to allow inverters to operate in more extreme operating conditions as required in advanced traction drive applications. The trend to try to eliminate secondary cooling loops and utilize the internal combustion (IC) cooling system, which operates with approximately 105 C water/ethylene glycol coolant at the output of the radiator, is necessary to further reduce vehicle costs and weight. The activity documented in this report includes development and testing of high temperature components, activities in support of high temperature testing, an assessment of several component packaging methods, and how elevated operating temperatures would impact their reliability. This report is organized with testing of new high temperature capacitors in Section 2 and testing of new 150 C junction temperature trench insulated gate bipolar transistor (IGBTs) in Section 3. Section 4 addresses some operational OPAL-GT information, which was necessary for developing module level tests. Section 5 summarizes calibration of equipment needed for the high temperature testing. Section 6 details some additional work that was funded on silicon carbide (SiC) device testing for high temperature use, and Section 7 is the complete text of a report funded from this effort summarizing packaging methods and their reliability issues for use in high temperature power electronics. Components were tested to evaluate the performance characteristics of the component at different operating temperatures. The temperature of the component is determined by the ambient temperature (i.e., temperature surrounding the device) plus the

  13. Ceramic membranes for high temperature hydrogen separation

    Energy Technology Data Exchange (ETDEWEB)

    Fain, D.E.; Roettger, G.E. [Oak Ridge K-25 Site, TN (United States)

    1996-08-01

    Ceramic gas separation membranes can provide very high separation factors if the pore size is sufficiently small to separate gas molecules by molecular sieving and if oversized pores are adequately limited. Ceramic membranes typically have some pores that are substantially larger than the mean pore size and that should be regarded as defects. To assess the effects of such defects on the performance of ceramic membranes, a simple mathematical model has been developed to describe flow through a gas separation membrane that has a primary mode of flow through very small pores but that has a secondary mode of flow through undesirably large pores. This model permits separation factors to be calculated for a specified gas pair as a function of the molecular weights and molecular diameters of the gases, the membrane pore diameter, and the diameter and number of defects. This model will be described, and key results from the model will be presented. The separation factors of the authors membranes continue to be determined using a permeance test system that measures flows of pure gases through a membrane at temperatures up to 275{degrees}C. A primary goal of this project for FY 1996 is to develop a mixed gas separation system for measuring the separation efficiency of membranes at higher temperatures. Performance criteria have been established for the planned mixed gas separation system and design of the system has been completed. The test system is designed to measure the separation efficiency of membranes at temperatures up to 600{degrees}C and pressures up to 100 psi by separating the constituents of a gas mixture containing hydrogen. The system will accommodate the authors typical experimental membrane that is tubular and has a diameter of about 9 mm and a length of about 23 cm. The design of the new test system and its expected performance will be discussed.

  14. High temperature skin friction measurement

    Science.gov (United States)

    Tcheng, Ping; Holmes, Harlan K.; Supplee, Frank H., Jr.

    1989-01-01

    Skin friction measurement in the NASA Langley hypersonic propulsion facility is described. The sensor configuration utilized an existing balance, modified to provide thermal isolation and an increased standoff distance. For test run times of about 20 sec and ambient-air cooling of the test section and balance, the modified balance performed satisfactorily, even when it was subjected to acoustic and structural vibration. The balance is an inertially balanced closed-loop servo system where the current to a moving-coil motor needed to restore or null the output from the position sensor is a measure of the force or skin friction tending to displace the moving element. The accuracy of the sensor is directly affected by the position sensor in the feedback loop, in this case a linear-variable differential transformer which has proven to be influenced by temperature gradients.

  15. Corrosion Resistant Coatings for High Temperature Applications

    Energy Technology Data Exchange (ETDEWEB)

    Besman, T.M.; Cooley, K.M.; Haynes, J.A.; Lee, W.Y.; Vaubert, V.M.

    1998-12-01

    Efforts to increase efficiency of energy conversion devices have required their operation at ever higher temperatures. This will force the substitution of higher-temperature structural ceramics for lower temperature materials, largely metals. Yet, many of these ceramics will require protection from high temperature corrosion caused by combustion gases, atmospheric contaminants, or the operating medium. This paper discusses examples of the initial development of such coatings and materials for potential application in combustion, aluminum smelting, and other harsh environments.

  16. Improving the temperature predictions of subsurface thermal models by using high-quality input data. Part 1: Uncertainty analysis of the thermal-conductivity parameterization

    DEFF Research Database (Denmark)

    Fuchs, Sven; Balling, Niels

    2016-01-01

    The subsurface temperature field and the geothermal conditions in sedimentary basins are frequently examined by using numerical thermal models. For those models, detailed knowledge of rock thermal properties are paramount for a reliable parameterization of layer properties and boundary conditions...... against known observed temperatures of good quality. Results clearly show that the use of location-specific well-log derived rock thermal properties and the integration of laterally varying input data (reflecting changes of lithofacies) significantly improves the temperature prediction...

  17. Thermodynamics of High Temperature Materials.

    Science.gov (United States)

    1986-09-30

    9S l~ SECUNT’~ C..&SSFCAr’CN OF ’-S OAGE REPORT DOCUMENTATION PAGE I &. EPO RT SEC URNITY CLASS P’CATION lb. RE£ST R CT IV I dAUNLSSIFIED M 4 j7...34 - :ne polymeric ions, and the repair mechanisms which regenerated the , polymeric ions after photodissociation. The model systems studied previously

  18. High-Temperature Passive Power Electronics

    Science.gov (United States)

    1997-01-01

    In many future NASA missions - such as deep-space exploration, the National AeroSpace Plane, minisatellites, integrated engine electronics, and ion or arcjet thrusters - high-power electrical components and systems must operate reliably and efficiently in high-temperature environments. The high-temperature power electronics program at the NASA Lewis Research Center focuses on dielectric and insulating material research, the development and characterization of high-temperature components, and the integration of the developed components into a demonstrable 200 C power system - such as an inverter. NASA Lewis has developed high-temperature power components through collaborative efforts with the Air Force Wright Laboratory, Northrop Grumman, and the University of Wisconsin. Ceramic and film capacitors, molypermalloy powder inductors, and a coaxially wound transformer were designed, developed, and evaluated for high-temperature operation.

  19. High-pressure and high-temperature physical properties of half-metallic full-Heusler alloy Mn2RuSi by first-principles and quasi-harmonic Debye model

    Science.gov (United States)

    Song, Ting; Ma, Qin; Sun, Xiao-Wei; Liu, Zi-Jiang; Wei, Xiao-Ping; Tian, Jun-Hong

    2017-02-01

    First-principles calculations based on density functional theory and quasi-harmonic Debye model are used to investigate the high-pressure and high-temperature physical properties, including the lattice constant, magnetic moment, density of states, pressure-volume-temperature relationship, bulk modulus, thermal expansivity, heat capacity, and Grüneisen parameter for the new Mn-based full-Heusler alloy Mn2RuSi in CuHg2Ti-type structure. The optimized equilibrium lattice constant is consistent with experimental and other theoretical results. The calculated total spin magnetic moment remains an integral value of 2.0 μB in the lattice constant range of 5.454-5.758 Å, and then decreases very slowly with the decrease of lattice constant to 5.333 Å. By the spin resolved density of states calculations, we have shown that Mn2RuSi compound presents half-metallic ferrimagnetic properties under the equilibrium lattice constant. The effects of temperature and pressure on bulk modulus, thermal expansivity, heat capacity, and Grüneisen parameter are opposite, which are consistent with a compression rate of volume. Furthermore, the results show that the effect of temperature is larger than pressure for heat capacity and the effect of high temperature and pressure on thermal expansion coefficient is small. All the properties of Mn2RuSi alloy are summarized in the pressure range of 0-100 GPa and the temperature up to 1200 K.

  20. Electrode Kinetics in High Temperature Fuel Cells

    DEFF Research Database (Denmark)

    Bay, Lasse

    1998-01-01

    The O_2 reduction on Pt electrode with an yttria stabilized zirconia (YSZ) electrolyte is examined with potential step, voltammetry and impedance measurements. Inductive hysteresis are observed in all cases, indicating an activation-deactivation process for the electrode reaction. The same is found...... when the electrolyte is Gd doped ceria. The activation is generated by current passage. The time constant for the hysteresis is large considering the high operating temperatures, 800- 1000^oC. For the activation process potential steps give two time constants 10^2s and 10^3s for an anodic current, 10...... treated by modelling. The phenomenological model proposed can explain the principal behaviour of the inductive hysteresis. The activation process has first order dependence of the current density and the deactivation first order with respect to the activation.AFM pictures of the electrode...

  1. High temperature polymer electrolyte membrane fuel cell

    Institute of Scientific and Technical Information of China (English)

    K.Scott; M. Mamlouk

    2006-01-01

    One of the major issues limiting the introduction of polymer electrolyte membrane fuel cells (PEMFCs) is the low temperature of operation which makes platinum-based anode catalysts susceptible to poisoning by the trace amount of CO, inevitably present in reformed fuel. In order to alleviate the problem of CO poisoning and improve the power density of the cell, operating at temperature above 100 ℃ is preferred. Nafion(R) -type perfluorosulfonated polymers have been typically used for PEMFC. However, the conductivity of Nafion(R) -type polymers is not high enough to be used for fuel cell operations at higher temperature ( > 90 ℃) and atmospheric pressure because they dehydrate under these condition.An additional problem which faces the introduction of PEMFC technology is that of supplying or storing hydrogen for cell operation,especially for vehicular applications. Consequently the use of alternative fuels such as methanol and ethanol is of interest, especially if this can be used directly in the fuel cell, without reformation to hydrogen. A limitation of the direct use of alcohol is the lower activity of oxidation in comparison to hydrogen, which means that power densities are considerably lower. Hence to improve activity and power output higher temperatures of operation are preferable. To achieve this goal, requires a new polymer electrolyte membrane which exhibits stability and high conductivity in the absence of liquid water.Experimental data on a polybenzimidazole based PEMFC were presented. A simple steady-state isothermal model of the fuel cell is also used to aid in fuel cell performance optimisation. The governing equations involve the coupling of kinetic, ohmic and mass transport. This paper also considers the advances made in the performance of direct methanol and solid polymer electrolyte fuel cells and considers their limitations in relation to the source and type of fuels to be used.

  2. A Road Towards High Temperature Superconductors

    Science.gov (United States)

    2013-08-01

    AFRL-AFOSR-UK-TR-2013-0040 A Road Towards High Temperature Superconductors Guy Deutscher Tel Aviv University Research... Superconductors 5a. CONTRACT NUMBER FA8655-10-1-3011 5b. GRANT NUMBER Grant 10-3011 5c. PROGRAM ELEMENT NUMBER 61102F 6. AUTHOR(S...issue in trying to make useful high temperature superconductors is obviously to discover superconductivity at higher temperatures. But there is also

  3. High Temperature Rechargeable Battery Development Project

    Data.gov (United States)

    National Aeronautics and Space Administration — This small business innovation research is intended to develop and proof the concept of a highly efficient, high temperature rechargeable battery for supporting...

  4. Lightweight, High-Temperature Radiator Panels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight, high-temperature radiators are needed for future, high-efficiency power conversion systems for Nuclear Electric Propulsion (NEP). Creare has developed...

  5. High Temperature Solid State Lithium Battery Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Reliable energy systems with high energy density capable of operating at high temperatures, pressures and radiation levels are needed for certain NASA missions....

  6. Lightweight, High-Temperature Radiator Panels Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Lightweight, high-temperature radiators are needed for future, high-efficiency power conversion systems for Nuclear Electric Propulsion (NEP). Creare has developed...

  7. Thermomechanics of composite structures under high temperatures

    CERN Document Server

    Dimitrienko, Yu I

    2016-01-01

    This pioneering book presents new models for the thermomechanical behavior of composite materials and structures taking into account internal physico-chemical transformations such as thermodecomposition, sublimation and melting at high temperatures (up to 3000 K). It is of great importance for the design of new thermostable materials and for the investigation of reliability and fire safety of composite structures. It also supports the investigation of interaction of composites with laser irradiation and the design of heat-shield systems. Structural methods are presented for calculating the effective mechanical and thermal properties of matrices, fibres and unidirectional, reinforced by dispersed particles and textile composites, in terms of properties of their constituent phases. Useful calculation methods are developed for characteristics such as the rate of thermomechanical erosion of composites under high-speed flow and the heat deformation of composites with account of chemical shrinkage. The author expan...

  8. High-Temperature Ionization in Protoplanetary Disks

    CERN Document Server

    Desch, Steven J

    2015-01-01

    We calculate the abundances of electrons and ions in the hot (> 500 K), dusty parts of protoplanetary disks, treating for the first time the effects of thermionic and ion emission from the dust grains. High-temperature ionization modeling has involved simply assuming that alkali elements such as potassium occur as gas-phase atoms and are collisionally ionized following the Saha equation. We show that the Saha equation often does not hold, because free charges are produced by thermionic and ion emission and destroyed when they stick to grain surfaces. This means the ionization state depends not on the first ionization potential of the alkali atoms, but rather on the grains' work functions. The charged species' abundances typically rise abruptly above about 800 K, with little qualitative dependence on the work function, gas density, or dust-to-gas mass ratio. Applying our results, we find that protoplanetary disks' dead zone, where high diffusivities stifle magnetorotational turbulence, has its inner edge locat...

  9. Ceramic fibres for high temperature insulation

    Energy Technology Data Exchange (ETDEWEB)

    Padgett, G.C.

    1986-03-01

    Traditionally, refractory linings for high temperature plant and furnaces have comprised either brick or some form of concrete. In recent years, energy conservation has encouraged the greater use of high temperature insulation which is also available in either brick or a lightweight concrete. As an alternative, insulation can also be achieved using fibrous products or fibres combining low heat transfer with low heat capacity.

  10. Regenerable MgO-based sorbents for high-temperature CO{sub 2} removal from syngas: 1. Sorbent development, evaluation, and reaction modeling

    Energy Technology Data Exchange (ETDEWEB)

    Armin Hassanzadeh; Javad Abbasian [Pyrophase Inc., Chicago, IL (United States)

    2010-06-15

    Highly reactive and mechanically strong low-cost regenerable MgO-based sorbents were prepared by modification of dolomite which involved partial calcinations followed by impregnation with a potassium-based salt. The sorbents are capable of removing CO{sub 2} from gasification-based processes such as Integrated Gasification Combined Cycle (IGCC). The sorbents have high reactivity and good capacity toward CO{sub 2} absorption in the temperature range of 300-450{sup o}C at 20 atm. and can be easily regenerated at 500{sup o}C. The reaction appears to be first order with respect to CO{sub 2} concentration with an activation energy of 44 kJ/mol. The reactivity and the absorption capacity of the sorbents increase with increasing temperature, as long as the partial pressure of CO{sub 2} is above the equilibrium value for sorbent carbonation. The reactivity of the sorbents appears to improve in the presence of steam, which is likely due to the increase in the BET surface area and the porosity of the sorbent. A two-zone expanding grain model, consisting of a high-reactivity outer shell and a low-reactivity inner core is shown to provide an excellent fit to the TGA experimental data on sorbent carbonation at various operating conditions. 31 refs., 16 figs.,3 tabs.

  11. Assessment of microelectronics packaging for high temperature, high reliability applications

    Energy Technology Data Exchange (ETDEWEB)

    Uribe, F.

    1997-04-01

    This report details characterization and development activities in electronic packaging for high temperature applications. This project was conducted through a Department of Energy sponsored Cooperative Research and Development Agreement between Sandia National Laboratories and General Motors. Even though the target application of this collaborative effort is an automotive electronic throttle control system which would be located in the engine compartment, results of this work are directly applicable to Sandia`s national security mission. The component count associated with the throttle control dictates the use of high density packaging not offered by conventional surface mount. An enabling packaging technology was selected and thermal models defined which characterized the thermal and mechanical response of the throttle control module. These models were used to optimize thick film multichip module design, characterize the thermal signatures of the electronic components inside the module, and to determine the temperature field and resulting thermal stresses under conditions that may be encountered during the operational life of the throttle control module. Because the need to use unpackaged devices limits the level of testing that can be performed either at the wafer level or as individual dice, an approach to assure a high level of reliability of the unpackaged components was formulated. Component assembly and interconnect technologies were also evaluated and characterized for high temperature applications. Electrical, mechanical and chemical characterizations of enabling die and component attach technologies were performed. Additionally, studies were conducted to assess the performance and reliability of gold and aluminum wire bonding to thick film conductor inks. Kinetic models were developed and validated to estimate wire bond reliability.

  12. Turbulent Flow past High Temperature Surfaces

    Science.gov (United States)

    Mehmedagic, Igbal; Thangam, Siva; Carlucci, Pasquale; Buckley, Liam; Carlucci, Donald

    2014-11-01

    Flow over high-temperature surfaces subject to wall heating is analyzed with applications to projectile design. In this study, computations are performed using an anisotropic Reynolds-stress model to study flow past surfaces that are subject to radiative flux. The model utilizes a phenomenological treatment of the energy spectrum and diffusivities of momentum and heat to include the effects of wall heat transfer and radiative exchange. The radiative transport is modeled using Eddington approximation including the weighted effect of nongrayness of the fluid. The time-averaged equations of motion and energy are solved using the modeled form of transport equations for the turbulence kinetic energy and the scalar form of turbulence dissipation with an efficient finite-volume algorithm. The model is applied for available test cases to validate its predictive capabilities for capturing the effects of wall heat transfer. Computational results are compared with experimental data available in the literature. Applications involving the design of projectiles are summarized. Funded in part by U.S. Army, ARDEC.

  13. The Analysis and Modeling of Phase Stability and Multiphase Designs in High Temperature Refractory Metal-Silicon-Boron Alloys

    Science.gov (United States)

    2009-01-27

    for subsequent Mo precipitation. In collaboration with Profesor A. Freeman we have analyzed the observed dislocation character in terms of the bonding...450 MPa and Y=106 GPa was obtained. It was found that it has the ideal stress transfer even for high loadings, which is a critical fundamental...Agarwal A., Tang Z., Ho S., Ingle P.’ Patterson D., Lu W., Kotov N. A., Nanostructured Thin Films made by Dewetting Method Of Layer-By-Layer Assembly

  14. Application of High Temperature Superconductors to Accelerators

    CERN Document Server

    Ballarino, A

    2000-01-01

    Since the discovery of high temperature superconductivity, a large effort has been made by the scientific community to investigate this field towards a possible application of the new oxide superconductors to different devices like SMES, magnetic bearings, flywheels energy storage, magnetic shielding, transmission cables, fault current limiters, etc. However, all present day large scale applications using superconductivity in accelerator technology are based on conventional materials operating at liquid helium temperatures. Poor mechanical properties, low critical current density and sensitivity to the magnetic field at high temperature are the key parameters whose improvement is essential for a large scale application of high temperature superconductors to such devices. Current leads, used for transferring currents from the power converters, working at room temperature, into the liquid helium environment, where the magnets are operating, represent an immediate application of the emerging technology of high t...

  15. Correlation Models for Temperature Fields

    KAUST Repository

    North, Gerald R.

    2011-05-16

    This paper presents derivations of some analytical forms for spatial correlations of evolving random fields governed by a white-noise-driven damped diffusion equation that is the analog of autoregressive order 1 in time and autoregressive order 2 in space. The study considers the two-dimensional plane and the surface of a sphere, both of which have been studied before, but here time is introduced to the problem. Such models have a finite characteristic length (roughly the separation at which the autocorrelation falls to 1/e) and a relaxation time scale. In particular, the characteristic length of a particular temporal Fourier component of the field increases to a finite value as the frequency of the particular component decreases. Some near-analytical formulas are provided for the results. A potential application is to the correlation structure of surface temperature fields and to the estimation of large area averages, depending on how the original datastream is filtered into a distribution of Fourier frequencies (e.g., moving average, low pass, or narrow band). The form of the governing equation is just that of the simple energy balance climate models, which have a long history in climate studies. The physical motivation provided by the derivation from a climate model provides some heuristic appeal to the approach and suggests extensions of the work to nonuniform cases.

  16. Atomic-scale Modeling of the Structure and Dynamics of Dislocations in Complex Alloys at High Temperatures

    Science.gov (United States)

    Daw, Murray S.; Mills, Michael J.

    2003-01-01

    We report on the progress made during the first year of the project. Most of the progress at this point has been on the theoretical and computational side. Here are the highlights: (1) A new code, tailored for high-end desktop computing, now combines modern Accelerated Dynamics (AD) with the well-tested Embedded Atom Method (EAM); (2) The new Accelerated Dynamics allows the study of relatively slow, thermally-activated processes, such as diffusion, which are much too slow for traditional Molecular Dynamics; (3) We have benchmarked the new AD code on a rather simple and well-known process: vacancy diffusion in copper; and (4) We have begun application of the AD code to the diffusion of vacancies in ordered intermetallics.

  17. Thermoelastic properties of minerals at high temperature

    Indian Academy of Sciences (India)

    Sanjay Upadhyay; Hem Chandra; Meenakashi Joshi; Deepika P Joshi

    2011-01-01

    The knowledge of elasticity of the minerals is useful for interpreting the structure and composition of the lower mantle and also in seismic studies. The purpose of the present study is to discuss a simple and straightforward method for evaluating thermoelastic properties of minerals at high temperatures. We have extended the Kumar’s formulation by taking into the account the concept of anharmonicity in minerals above the Debye temperature (D). In our present study, we have investigated the thermophysical properties of two minerals (pyrope-rich garnet and MgAl2O4) under high temperatures and calculated the second-order elastic constant () and bulk modulus (T) of the above minerals, in two cases first by taking Anderson–Gruneisen parameter (T) as temperature-independent and then by treating T as temperature-dependent parameter. The results obtained when T is temperature-dependent are in close agreement with experimental data.

  18. High Temperature Softening Behaviors and Flow Stress Model for a High Molybdenum Austenitic Stainless Steel%高钼奥氏体不锈钢高温软化行为与流变应力模型

    Institute of Scientific and Technical Information of China (English)

    2000-01-01

    Single-stage and double-stage interrupted hot compression tests for physical simulating hot rolling have been carried out on the THERMECMATSTOR-Z simulator for 00Cr20Ni18Mo6Cu[ N] austenitic stainless steel under high temperature (1223~1373 K) and various strain rates (0.1~60 s- 1 ). The high temperature mechanical behaviors and microstructure evolution of the steel were studied. The activation energies of hot deformation and dynamic, static and metadynamic recrystallization were calculated. Serials of perfect flow stress model considering dynamic recrystallization were established. The predicted result by the model was well agreed with the experiment data.The kinetics of metadynamic and static recrystallization had also been determined.

  19. Low to high temperature energy conversion system

    Science.gov (United States)

    Miller, C. G. (Inventor)

    1977-01-01

    A method for converting heat energy from low temperature heat sources to higher temperature was developed. It consists of a decomposition chamber in which ammonia is decomposed into hydrogen and nitrogen by absorbing heat of decomposition from a low temperature energy source. A recombination reaction then takes place which increases the temperature of a fluid significantly. The system is of use for the efficient operation of compact or low capital investment turbine driven electrical generators, or in other applications, to enable chemical reactions that have a critical lower temperature to be used. The system also recovers heat energy from low temperature heat sources, such as solar collectors or geothermal sources, and converts it to high temperatures.

  20. Sandia_HighTemperatureComponentEvaluation_2015

    Energy Technology Data Exchange (ETDEWEB)

    Cashion, Avery T. [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2015-03-01

    The objective of this project is to perform independent evaluation of high temperature components to determine their suitability for use in high temperature geothermal tools. Development of high temperature components has been increasing rapidly due to demand from the high temperature oil and gas exploration and aerospace industries. Many of these new components are at the late prototype or first production stage of development and could benefit from third party evaluation of functionality and lifetime at elevated temperatures. In addition to independent testing of new components, this project recognizes that there is a paucity of commercial-off-the-shelf COTS components rated for geothermal temperatures. As such, high-temperature circuit designers often must dedicate considerable time and resources to determine if a component exists that they may be able to knead performance out of to meet their requirements. This project aids tool developers by characterization of select COTS component performances beyond published temperature specifications. The process for selecting components includes public announcements of project intent (e.g., FedBizOps), direct discussions with candidate manufacturers,and coordination with other DOE funded programs.

  1. The temperature change in an endotracheal tube during high frequency ventilation using an artificial neonatal lung model with Babylog® 8000 plus.

    Science.gov (United States)

    Nagaya, Ken; Tsuchida, Etsushi; Nohara, Fumikatsu; Okamoto, Toshio; Azuma, Hiroshi

    2015-02-01

    There is little available data on airway humidity during high-frequency ventilation (HFV). The purpose of this study is to evaluate the temperature drop in an endotracheal tube (ETT) during HFV. We examined the airway temperature in a neonatal HFV system using Babylog® 8000 plus. We measured the temperature change of inspired gases in the ETT under various oscillatory frequencies and oscillatory volumes with a fixed base flow. The temperatures in the ETT during HFV were compared with the temperatures during conventional intermittent positive pressure ventilation (IPPV). As the oscillatory frequency was increased and the oscillatory volume (VThf) decreased, the difference in temperature between the Y piece and the inlet of an artificial lung in the ETT (ETT outside of body) increased. However, as the oscillatory frequency increased, there was no difference in the ETT temperature under constant oscillatory volume. In contrast, as the oscillatory volume was decreased, the difference in temperature in the ETT was greater under constant oscillatory frequency. Moreover, the temperature drop in the ETT with HFV was lower than that in the IPPV temperature with a similar respiratory volume. The temperature change in the ETT was not dependent on the oscillatory frequency when the oscillatory volume was fixed; however, the temperature was dependent on the oscillatory volume when the oscillatory frequency was fixed. © 2013 Wiley Periodicals, Inc.

  2. STUDY OF NUMERICAL MODELING OF SHAPE DEFORMING ZONE OF DIES, DURING DRAWING HIGH CARBON STEEL WIRE TO THE TEMPERATURE AND THE STRESS-STRAIN STATE IN THE WIRE AND DIE

    Directory of Open Access Journals (Sweden)

    O. L. Bobarikin

    2012-01-01

    Full Text Available Investigation by numerical modeling of influence of the form of deforming zone of die at drawing of steel high- carbon wire on temperature and strained-deformed state in wire and die is carried out.

  3. Aeronautical applications of high-temperature superconductors

    Science.gov (United States)

    Turney, George E.; Luidens, Roger W.; Uherka, Kenneth; Hull, John

    1989-01-01

    The successful development of high-temperature superconductors (HTS) could have a major impact on future aeronautical propulsion and aeronautical flight vehicle systems. A preliminary examination of the potential application of HTS for aeronautics indicates that significant benefits may be realized through the development and implementation of these newly discovered materials. Applications of high-temperature superconductors (currently substantiated at 95 k) were envisioned for several classes of aeronautical systems, including subsonic and supersonic transports, hypersonic aircraft, V/STOL aircraft, rotorcraft, and solar, microwave and laser powered aircraft. Introduced and described are the particular applications and potential benefits of high-temperature superconductors as related to aeronautics and/or aeronautical systems.

  4. Aeronautical applications of high-temperature superconductors

    Science.gov (United States)

    Turney, George E.; Luidens, Roger W.; Uherka, Kenneth; Hull, John

    1989-01-01

    The successful development of high-temperature superconductors (HTS) could have a major impact on future aeronautical propulsion and aeronautical flight vehicle systems. A preliminary examination of the potential application of HTS for aeronautics indicates that significant benefits may be realized through the development and implementation of these newly discovered materials. Applications of high-temperature superconductors (currently substantiated at 95 K) were envisioned for several classes of aeronautical systems, including subsonic and supersonic transports, hypersonic aircraft, V/STOL aircraft, rotorcraft, and solar, microwave and laser powered aircraft. Introduced and described are the particular applications and potential benefits of high-temperature superconductors as related to aeronautics and/or aeronautical systems.

  5. High temperature and pressure alkaline electrolysis

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2013-01-01

    the operational temperature and pressure to produce pressurized hydrogen at high rate (m3 H2·h-1·m-2 cell area) and high electrical efficiency. This work describes an exploratory technical study of the possibility to produce hydrogen and oxygen with a new type of alkaline electrolysis cell at high temperatures...... for immobilization of aqueous KOH solutions. Electrolysis cells with this electrolyte and metal foam based gas diffusion electrodes were successfully demonstrated at temperatures up to 250 °C at 40 bar. Different electro-catalysts were tested in order to reduce the oxygen and hydrogen overpotentials. Current...

  6. Symposium on high temperature and materials chemistry

    Energy Technology Data Exchange (ETDEWEB)

    1989-10-01

    This volume contains the written proceedings of the Symposium on High Temperature and Materials Chemistry held in Berkeley, California on October 24--25, 1989. The Symposium was sponsored by the Materials and Chemical Sciences Division of Lawrence Berkeley Laboratory and by the College of Chemistry of the University of California at Berkeley to discuss directions, trends, and accomplishments in the field of high temperature and materials chemistry. Its purpose was to provide a snapshot of high temperature and materials chemistry and, in so doing, to define status and directions.

  7. Silicon Carbide Nanotube Oxidation at High Temperatures

    Science.gov (United States)

    Ahlborg, Nadia; Zhu, Dongming

    2012-01-01

    Silicon Carbide Nanotubes (SiCNTs) have high mechanical strength and also have many potential functional applications. In this study, SiCNTs were investigated for use in strengthening high temperature silicate and oxide materials for high performance ceramic nanocomposites and environmental barrier coating bond coats. The high · temperature oxidation behavior of the nanotubes was of particular interest. The SiCNTs were synthesized by a direct reactive conversion process of multiwall carbon nanotubes and silicon at high temperature. Thermogravimetric analysis (TGA) was used to study the oxidation kinetics of SiCNTs at temperatures ranging from 800degC to1300degC. The specific oxidation mechanisms were also investigated.

  8. High-Temperature, High-Concentration Solar Thermoelectric Generators

    Science.gov (United States)

    Warren, Emily; Baranowski, Lauryn; Olsen, Michele; Ndione, Paul; Netter, Judy; Goodrich, Alan; Gray, Matthew; Parilla, Philip; Ginley, David; Toberer, Eric

    2014-03-01

    Solar thermoelectric generators (STEGs) powered with concentrated solar energy have potential for use as primary energy converters or as topping-cycles for more conventional concentrated solar power (CSP) technologies. Modeling based on current record modules from JPL suggests thermoelectric efficiencies of 18 % could be experimentally expected with a temperature gradient of 1000 - 100°C. Integrating these state-of-the-art TEGs with a concentrating solar receiver requires simultaneous optimization of optical, thermal, and thermoelectric systems. This talk will discuss the modeling, design, and experimental testing of STEG devices under concentrated sunlight. We have developed a model that combines thermal circuit modeling with optical ray tracing to design selective absorber coatings and cavities to minimize radiation losses from the system. We have fabricated selective absorber coatings and demonstrated that these selective absorber films can minimize blackbody radiation losses at high temperature and are stable after thermal cycling to 1000°C. On-sun testing of STEG devices and thermal simulators is ongoing and preliminary results will be discussed.

  9. Meth math: modeling temperature responses to methamphetamine.

    Science.gov (United States)

    Molkov, Yaroslav I; Zaretskaia, Maria V; Zaretsky, Dmitry V

    2014-04-15

    Methamphetamine (Meth) can evoke extreme hyperthermia, which correlates with neurotoxicity and death in laboratory animals and humans. The objective of this study was to uncover the mechanisms of a complex dose dependence of temperature responses to Meth by mathematical modeling of the neuronal circuitry. On the basis of previous studies, we composed an artificial neural network with the core comprising three sequentially connected nodes: excitatory, medullary, and sympathetic preganglionic neuronal (SPN). Meth directly stimulated the excitatory node, an inhibitory drive targeted the medullary node, and, in high doses, an additional excitatory drive affected the SPN node. All model parameters (weights of connections, sensitivities, and time constants) were subject to fitting experimental time series of temperature responses to 1, 3, 5, and 10 mg/kg Meth. Modeling suggested that the temperature response to the lowest dose of Meth, which caused an immediate and short hyperthermia, involves neuronal excitation at a supramedullary level. The delay in response after the intermediate doses of Meth is a result of neuronal inhibition at the medullary level. Finally, the rapid and robust increase in body temperature induced by the highest dose of Meth involves activation of high-dose excitatory drive. The impairment in the inhibitory mechanism can provoke a life-threatening temperature rise and makes it a plausible cause of fatal hyperthermia in Meth users. We expect that studying putative neuronal sites of Meth action and the neuromediators involved in a detailed model of this system may lead to more effective strategies for prevention and treatment of hyperthermia induced by amphetamine-like stimulants.

  10. Development of high temperature capable piezoelectric sensors

    Science.gov (United States)

    Suprock, Andrew D.; Tittmann, Bernhard R.

    2017-02-01

    The objective of the project was to investigate the influence of the temperature effect on ultrasonic transducers based on a comparison of the effects of high temperature conditions versus those of high temperature and irradiation on the transducer system. There was also a preliminary move towards the establishment of the means for optimizing the bulk single crystal transducer fabrication process in order to achieve peak efficiency and maximum effectiveness in both irradiated and non-irradiated high temperature applications. Optimization of the material components within the transducer will greatly increase non-destructive testing abilities for industry, structural health monitoring. Here is presented a progress report on the testing of several different piezoelectric materials under high temperature conditions. The viability of aluminum nitride (AlN) as a transducer material in high temperature conditions has been previously explored [1] and has been further tested to ensure reliability. Bistmuth Titanate (BiT) has also been tested and has displayed excellent effectiveness for high temperature application.

  11. Broadband, High-Temperature Ultrasonic Transducer

    Science.gov (United States)

    Parker, F. Raymond; Winfree, William P.; Barrows, Danny A.

    1995-01-01

    Materials chosen for endurance at high temperatures and acoustic coupling and damping. Acoustic transducer designed to exhibit broad frequency response and to survive temperatures close to melting points of brazing alloys. Attached directly and continuously to hot object monitored ultrasonically: for example, it can be attached to relatively cool spot on workpiece during brazing for taking ultrasonic quality-control measurements.

  12. A library of extended high-temperature expansions of basic observables for the spin S Ising models on two- and three-dimensional lattices

    CERN Document Server

    Butera, P

    2002-01-01

    We present an on-line library of unprecedented extension for high-temperature expansions of basic observables in the Ising models of general spin S, with nearest-neighbor interactions. We have tabulated through order beta^{25} the series for the nearest-neighbor correlation function, the susceptibility and the second correlation moment in two dimensions on the square lattice, and, in three dimensions, on the simple-cubic and the body-centered cubic lattices. The expansion of the second field derivative of the susceptibility is also tabulated through beta^{23} for the same lattices. We have thus added several terms (from four up to thirteen) to the series already published for spin S=1/2,1,3/2,2,5/2,3,7/2,4,5,infinity.

  13. A nonlinear multi-proxy model based on manifold learning to reconstruct water temperature from high resolution trace element profiles in biogenic carbonates

    Directory of Open Access Journals (Sweden)

    M. Bauwens

    2010-07-01

    Full Text Available A long standing problem in paleoceanography concerns the reconstruction of water temperature from δ18O carbonate, which for freshwater influenced environments is hindered because the isotopic composition of the ambient water (related to salinity affects the reconstructed temperature. In this paper we argue for the use of a nonlinear multi-proxy method called Weight Determination by Manifold Regularization to develop a temperature reconstruction model that is less sensitive to salinity variations. The motivation for using this type of model is twofold: Firstly, observed nonlinear relations between specific proxies and water temperature motivate the use of nonlinear models. Secondly, the use of multi-proxy models enables salinity related variations of a given temperature proxy to be explained by salinity-related information carried by a separate proxy. Our findings confirm that Mg/Ca is a powerful paleothermometer and highlight that reconstruction performance based on this proxy is improved significantly by combining its information with the information of other trace elements in multi-proxy models. Using Mg/Ca, Sr/Ca, Ba/Ca and Pb/Ca the WDMR model enabled a temperature reconstruction with a root mean squared error of ±2.19 °C for a salinity range between 15 and 32.

  14. High Temperature Fiberoptic Thermal Imaging System Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed Phase 1 program will fabricate and demonstrate a small diameter single fiber endoscope that can perform high temperature thermal imaging in a jet engine...

  15. High Temperature Self-Healing Metallic Composite

    Science.gov (United States)

    Kutelia, E. R.; Bakhtiyarov, S. I.; Tsurtsumia, O. O.; Bakhtiyarov, A. S.; Eristavi, B.

    2012-01-01

    This work presents the possibility to realize the self healing mechanisms for heterogeneous architectural metal/ceramic high temperature sandwich thermal barrier coating systems on the surfaces refractory metals by analogy of wound healing in the skin.

  16. High Temperature Capacitors for Venus Exploration Project

    Data.gov (United States)

    National Aeronautics and Space Administration — High temperature power electronics have become a vital aspect of future designs for power converters in spacecraft, battle zone electric power, satellite power...

  17. Panel report on high temperature ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Nolet, T C [ed.

    1979-01-01

    Fundamental research is reported concerning high temperature ceramics for application in turbines, engines, batteries, gasifiers, MHD, fuel cells, heat exchangers, and hot wall combustors. Ceramics microstructure and behavior are included. (FS)

  18. Application Fields of High-Temperature Superconductors

    OpenAIRE

    Hott, Roland

    2003-01-01

    Potential application fields for cuprate high-temperature superconductors (HTS) and the status of respective projects are reviewed. The availability of a reliable and inexpensive cooling technique will be essential for a future broad acceptance of HTS applications.

  19. Measuring Moduli Of Elasticity At High Temperatures

    Science.gov (United States)

    Wolfenden, Alan

    1993-01-01

    Shorter, squatter specimens and higher frequencies used in ultrasonic measurement technique. Improved version of piezo-electric ultrasonic composite oscillator technique used to measure moduli of elasticity of solid materials at high temperatures.

  20. Silicon carbide, an emerging high temperature semiconductor

    Science.gov (United States)

    Matus, Lawrence G.; Powell, J. Anthony

    1991-01-01

    In recent years, the aerospace propulsion and space power communities have expressed a growing need for electronic devices that are capable of sustained high temperature operation. Applications for high temperature electronic devices include development instrumentation within engines, engine control, and condition monitoring systems, and power conditioning and control systems for space platforms and satellites. Other earth-based applications include deep-well drilling instrumentation, nuclear reactor instrumentation and control, and automotive sensors. To meet the needs of these applications, the High Temperature Electronics Program at the Lewis Research Center is developing silicon carbide (SiC) as a high temperature semiconductor material. Research is focussed on developing the crystal growth, characterization, and device fabrication technologies necessary to produce a family of silicon carbide electronic devices and integrated sensors. The progress made in developing silicon carbide is presented, and the challenges that lie ahead are discussed.

  1. Novel High Temperature Strain Gauge Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Advanced high-temperature sensor technology and bonding methods are of great interests in designing and developing advanced future aircraft. Current state-of-the-art...

  2. High temperature superconductors and other superfluids

    CERN Document Server

    Alexandrov, A S

    2017-01-01

    Written by eminent researchers in the field, this text describes the theory of superconductivity and superfluidity starting from liquid helium and a charged Bose-gas. It also discusses the modern bipolaron theory of strongly coupled superconductors, which explains the basic physical properties of high-temperature superconductors. This book will be of interest to fourth year graduate and postgraduate students, specialist libraries, information centres and chemists working in high-temperature superconductivity.

  3. PLA recycling by hydrolysis at high temperature

    Science.gov (United States)

    Cristina, Annesini Maria; Rosaria, Augelletti; Sara, Frattari; Fausto, Gironi

    2016-05-01

    In this work the process of PLA hydrolysis at high temperature was studied, in order to evaluate the possibility of chemical recycling of this polymer bio-based. In particular, the possibility to obtain the monomer of lactic acid from PLA degradation was investigated. The results of some preliminary tests, performed in a laboratory batch reactor at high temperature, are presented: the experimental results show that the complete degradation of PLA can be obtained in relatively low reaction times.

  4. Recent developments in high temperature organic polymers

    Science.gov (United States)

    Hergenrother, P. M.

    1991-01-01

    Developments in high temperature organic polymers during the last 5 years with major emphasis on polyimides and poly(arylene ether)s are discussed. Specific polymers or series of polymers have been selected to demonstrate unique properties or the effect chemical structure has upon certain properties. This article is not intended to be a comprehensive review of high temperature polymer advancements during the last 5 years.

  5. High-temperature discontinuously reinforced aluminum

    Science.gov (United States)

    Zedalis, M. S.; Bryant, J. D.; Gilman, P. S.; Das, S. K.

    1991-08-01

    High-temperature discontinuously reinforced aluminum (HTDRA) composites have been developed for elevated-temperature applications by incorporating SiC particulate reinforcement into a rapidly solidified, high-temperature Al-Fe-V-Si (alloy 8009) matrix. HTDRA combines the superior elevated-temperature strength, stability and corrosion resistance of the 8009 matrix with the excellent specific stiffness and abrasion resistance of the discontinuous SiC particulate reinforcement. On a specific stiffness basis, HTDRA is competitive with Ti-6-Al-4V and 17-4 PH stainless steel to temperatures approaching 480°C. Potential aerospace applications being considered for HTDRA include aircraft wing skins, missile bodies, and miscellaneous engine, spacecraft and hypersonic vehicle components.

  6. Multiscale Modeling of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2: Application to Lattice Thermal Conductivity

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Squire, Thomas H.; Bauschlicher, Charles W.

    2012-01-01

    We are developing a multiscale framework in computational modeling for the ultra high temperature ceramics (UHTC) ZrB2 and HfB2. These materials are characterized by high melting point, good strength, and reasonable oxidation resistance. They are candidate materials for a number of applications in extreme environments including sharp leading edges of hypersonic aircraft. In particular, we used a combination of ab initio methods, atomistic simulations and continuum computations to obtain insights into fundamental properties of these materials. Ab initio methods were used to compute basic structural, mechanical and thermal properties. From these results, a database was constructed to fit a Tersoff style interatomic potential suitable for atomistic simulations. These potentials were used to evaluate the lattice thermal conductivity of single crystals and the thermal resistance of simple grain boundaries. Finite element method (FEM) computations using atomistic results as inputs were performed with meshes constructed on SEM images thereby modeling the realistic microstructure. These continuum computations showed the reduction in thermal conductivity due to the grain boundary network.

  7. Modeling and experimental performance of an intermediate temperature reversible solid oxide cell for high-efficiency, distributed-scale electrical energy storage

    Science.gov (United States)

    Wendel, Christopher H.; Gao, Zhan; Barnett, Scott A.; Braun, Robert J.

    2015-06-01

    Electrical energy storage is expected to be a critical component of the future world energy system, performing load-leveling operations to enable increased penetration of renewable and distributed generation. Reversible solid oxide cells, operating sequentially between power-producing fuel cell mode and fuel-producing electrolysis mode, have the capability to provide highly efficient, scalable electricity storage. However, challenges ranging from cell performance and durability to system integration must be addressed before widespread adoption. One central challenge of the system design is establishing effective thermal management in the two distinct operating modes. This work leverages an operating strategy to use carbonaceous reactant species and operate at intermediate stack temperature (650 °C) to promote exothermic fuel-synthesis reactions that thermally self-sustain the electrolysis process. We present performance of a doped lanthanum-gallate (LSGM) electrolyte solid oxide cell that shows high efficiency in both operating modes at 650 °C. A physically based electrochemical model is calibrated to represent the cell performance and used to simulate roundtrip operation for conditions unique to these reversible systems. Design decisions related to system operation are evaluated using the cell model including current density, fuel and oxidant reactant compositions, and flow configuration. The analysis reveals tradeoffs between electrical efficiency, thermal management, energy density, and durability.

  8. Relativistic QED Plasma at Extremely High Temperature

    CERN Document Server

    Masood, Samina S

    2016-01-01

    Renormalization scheme of QED (Quantum Electrodynamics) at high temperatures is used to calculate the effective parameters of relativistic plasma in the early universe. Renormalization constants of QED play role of effective parameters of the theory and can be used to determine the collective behavior of the medium. We explicitly show that the dielectric constant, magnetic reluctivity, Debye length and the plasma frequency depend on temperature in the early universe. Propagation speed, refractive index, plasma frequency and Debye shielding length of a QED plasma are computed at extremely high temperatures in the early universe. We also found the favorable conditions for the relativistic plasma from this calculations.

  9. The first three coefficients in the high temperature series expansion of free energy for simple potential models with hard-sphere cores and continuous tails.

    Science.gov (United States)

    Zhou, Shiqi; Solana, J R

    2013-08-08

    The first three coefficients of the high temperature series expansion (HTSE) of the Helmholtz free energy for a number of simple potential models with hard-sphere cores plus continuous tails are obtained for the first time from Monte Carlo simulations. The potential models considered include Square-well, Sutherland, attractive Yukawa, and triangle-well with different potential ranges, as well as a model potential qualitatively resembling the depletion potential in colloidal dispersions. The simulation data are used to evaluate performance of a recent coupling parameter series expansion (CPSE) in calculating for these coefficients, and a traditional macroscopic compressibility approximation (MCA) for the second-order coefficient only. A comprehensive comparison based on these coefficients from the two theoretical approaches and simulations enables one to conclude that (i) unlike one common experience that the widely used MCA usually underestimates the second-order coefficient, the MCA can both overestimate and underestimate the second-order coefficient, and worsens as the range of the potential decreases; and (ii) in contrast, the CPSE not only reproduce the trends in the density dependence of the perturbation coefficients, even the third one, observed in the simulations, but also the agreement is quantitative in most cases, and this clearly highlights the potential of the CPSE in providing accurate estimations for the higher-order coefficients, thus giving rise to an accurate higher-order HTSE.

  10. Design of High Field Solenoids made of High Temperature Superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Bartalesi, Antonio; /Pisa U.

    2010-12-01

    This thesis starts from the analytical mechanical analysis of a superconducting solenoid, loaded by self generated Lorentz forces. Also, a finite element model is proposed and verified with the analytical results. To study the anisotropic behavior of a coil made by layers of superconductor and insulation, a finite element meso-mechanic model is proposed and designed. The resulting material properties are then used in the main solenoid analysis. In parallel, design work is performed as well: an existing Insert Test Facility (ITF) is adapted and structurally verified to support a coil made of YBa{sub 2}Cu{sub 3}O{sub 7}, a High Temperature Superconductor (HTS). Finally, a technological winding process was proposed and the required tooling is designed.

  11. Melt processed high-temperature superconductors

    CERN Document Server

    1993-01-01

    The achievement of large critical currents is critical to the applications of high-temperature superconductors. Recent developments have shown that melt processing is suitable for producing high J c oxide superconductors. Using magnetic forces between such high J c oxide superconductors and magnets, a person could be levitated.This book has grown largely out of research works on melt processing of high-temperature superconductors conducted at ISTEC Superconductivity Research Laboratory. The chapters build on melt processing, microstructural characterization, fundamentals of flux pinning, criti

  12. High Temperature, Wireless Seismometer Sensor for Venus

    Science.gov (United States)

    Ponchak, George E.; Scardelletti, Maximilian C.; Taylor, Brandt; Beard, Steve; Meredith, Roger D.; Beheim, Glenn M.; Hunter Gary W.; Kiefer, Walter S.

    2012-01-01

    Space agency mission plans state the need to measure the seismic activity on Venus. Because of the high temperature on Venus (462? C average surface temperature) and the difficulty in placing and wiring multiple sensors using robots, a high temperature, wireless sensor using a wide bandgap semiconductor is an attractive option. This paper presents the description and proof of concept measurements of a high temperature, wireless seismometer sensor for Venus. A variation in inductance of a coil caused by the movement of an aluminum probe held in the coil and attached to a balanced leaf-spring seismometer causes a variation of 700 Hz in the transmitted signal from the oscillator/sensor system at 426? C. This result indicates that the concept may be used on Venus.

  13. High-temperature granulites and supercontinents

    Institute of Scientific and Technical Information of China (English)

    J.L.R. Touret; M. Santosh; J.M. Huizenga

    2016-01-01

    The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T) conditions of (ultra) high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones (high-pressure metamorphic setting), and vertically by accumulation of mantle-derived magmas at the base of the crust (high-temperature metamorphic setting). Both events are separated from each other in time; the vertical accretion post-dating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions (brines). These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust. This accumulation causes tectonic instability, which together with the heat input from the sub-continental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.

  14. High-temperature granulites and supercontinents

    Directory of Open Access Journals (Sweden)

    J.L.R. Touret

    2016-01-01

    Full Text Available The formation of continents involves a combination of magmatic and metamorphic processes. These processes become indistinguishable at the crust-mantle interface, where the pressure-temperature (P-T conditions of (ultra high-temperature granulites and magmatic rocks are similar. Continents grow laterally, by magmatic activity above oceanic subduction zones (high-pressure metamorphic setting, and vertically by accumulation of mantle-derived magmas at the base of the crust (high-temperature metamorphic setting. Both events are separated from each other in time; the vertical accretion postdating lateral growth by several tens of millions of years. Fluid inclusion data indicate that during the high-temperature metamorphic episode the granulite lower crust is invaded by large amounts of low H2O-activity fluids including high-density CO2 and concentrated saline solutions (brines. These fluids are expelled from the lower crust to higher crustal levels at the end of the high-grade metamorphic event. The final amalgamation of supercontinents corresponds to episodes of ultra-high temperature metamorphism involving large-scale accumulation of these low-water activity fluids in the lower crust. This accumulation causes tectonic instability, which together with the heat input from the sub-continental lithospheric mantle, leads to the disruption of supercontinents. Thus, the fragmentation of a supercontinent is already programmed at the time of its amalgamation.

  15. An integrated model of tritium transport and corrosion in Fluoride Salt-Cooled High-Temperature Reactors (FHRs) – Part I: Theory and benchmarking

    Energy Technology Data Exchange (ETDEWEB)

    Stempien, John D., E-mail: john.stempien@inl.gov; Ballinger, Ronald G., E-mail: hvymet@mit.edu; Forsberg, Charles W., E-mail: cforsber@mit.edu

    2016-12-15

    Highlights: • A model was developed for use with FHRs and benchmarked with experimental data. • Model results match results of tritium diffusion experiments. • Corrosion simulations show reasonable agreement with molten salt loop experiments. • This is the only existing model of tritium transport and corrosion in FHRs. • Model enables proposing and evaluating tritium control options in FHRs. - Abstract: The Fluoride Salt-Cooled High-Temperature Reactor (FHR) is a pebble bed nuclear reactor concept cooled by a liquid fluoride salt known as “flibe” ({sup 7}LiF-BeF{sub 2}). A model of TRITium Diffusion EvolutioN and Transport (TRIDENT) was developed for use with FHRs and benchmarked with experimental data. TRIDENT is the first model to integrate the effects of tritium production in the salt via neutron transmutation, with the effects of the chemical redox potential, tritium mass transfer, tritium diffusion through pipe walls, tritium uptake by graphite, selective chromium attack by tritium fluoride, and corrosion product mass transfer. While data from a forced-convection polythermal loop of molten salt containing tritium did not exist for comparison, TRIDENT calculations were compared to data from static salt diffusion tests in flibe and flinak (0.465LiF-0.115NaF-0.42KF) salts. In each case, TRIDENT matched the transient and steady-state behavior of these tritium diffusion experiments. The corrosion model in TRIDENT was compared against the natural convection flow-loop experiments at the Oak Ridge National Laboratory (ORNL) from the 1960s and early 1970s which used Molten Salt Reactor Experiment (MSRE) fuel-salt containing UF{sub 4}. Despite the lack of data required by TRIDENT for modeling the loops, some reasonable results were obtained. The TRIDENT corrosion rates follow the experimentally observed dependence on the square root of the product of the chromium solid-state diffusion coefficient with time. Additionally the TRIDENT model predicts mass

  16. High-temperature spreading kinetics of metals

    Energy Technology Data Exchange (ETDEWEB)

    Rauch, N.

    2005-05-15

    In this PhD work a drop transfer setup combined with high speed photography has been used to analyze the spreading of Ag on polished polycrystalline Mo and single crystalline Mo (110) and (100) substrates. The objective of this work was to unveil the basic phenomena controlling spreading in metal-metal systems. The observed spreading kinetics were compared with current theories of low and high temperature spreading such as a molecular kinetic model and a fluid flow model. Analyses of the data reveal that the molecular model does describe the fastest velocity data well for all the investigated systems. Therefore, the energy which is dissipated during the spreading process is a dissipation at the triple line rather than dissipation due to the viscosity in the liquid. A comparison of the determined free activation energy for wetting of {delta}G95{approx}145kJ/mol with literature values allows the statement that the rate determining step seems to be a surface diffusion of the Ag atoms along the triple line. In order to investigate possible ridge formation, due to local atomic diffusion of atoms of the substrate at the triple during the spreading process, grooving experiments of the polycrystalline Mo were performed to calculate the surface diffusities that will control ridge evolution. The analyses of this work showed that a ridge formation at the fastest reported wetting velocities was not possible if there is no initial perturbation for a ridge. If there was an initial perturbation for a ridge the ridge had to be much smaller than 1 nm in order to be able to move with the liquid font. Therefore ridge formation does not influence the spreading kinetics for the studied system and the chosen conditions. SEM, AFM and TEM investigations of the triple line showed that ridge formation does also not occur at the end of the wetting experiment when the drop is close to equilibrium and the wetting velocity is slow. (orig.)

  17. High temperature effects on compact-like structures

    Energy Technology Data Exchange (ETDEWEB)

    Bazeia, D.; Lima, E.E.M.; Losano, L. [Universidade Federal da Paraiba, Departamento de Fisica, Joao Pessoa, PB (Brazil)

    2016-08-15

    In this work we investigate the transition from kinks to compactons at high temperatures. We deal with a family of models, described by a real scalar field with standard kinematics, controlled by a single parameter, real and positive. The family of models supports kink-like solutions, and the solutions tend to become compact when the parameter increases to larger and larger values. We study the one-loop corrections at finite temperature, to see how the thermal effects add to the effective potential. The results suggest that the symmetry is restored at very high temperatures. (orig.)

  18. High-entropy alloys as high-temperature thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Shafeie, Samrand [Surface and Microstructure Engineering Group, Materials and Manufacturing Technology, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Guo, Sheng, E-mail: sheng.guo@chalmers.se [Surface and Microstructure Engineering Group, Materials and Manufacturing Technology, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Hu, Qiang [Institute of Applied Physics, Jiangxi Academy of Sciences, Nanchang 330029 (China); Fahlquist, Henrik [Bruker AXS Nordic AB, 17067 Solna (Sweden); Erhart, Paul [Department of Applied Physics, Chalmers University of Technology, SE-41296 Gothenburg (Sweden); Palmqvist, Anders, E-mail: anders.palmqvist@chalmers.se [Department of Chemistry and Chemical Engineering, Chalmers University of Technology, SE-41296 Gothenburg (Sweden)

    2015-11-14

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  19. High-entropy alloys as high-temperature thermoelectric materials

    Science.gov (United States)

    Shafeie, Samrand; Guo, Sheng; Hu, Qiang; Fahlquist, Henrik; Erhart, Paul; Palmqvist, Anders

    2015-11-01

    Thermoelectric (TE) generators that efficiently recycle a large portion of waste heat will be an important complementary energy technology in the future. While many efficient TE materials exist in the lower temperature region, few are efficient at high temperatures. Here, we present the high temperature properties of high-entropy alloys (HEAs), as a potential new class of high temperature TE materials. We show that their TE properties can be controlled significantly by changing the valence electron concentration (VEC) of the system with appropriate substitutional elements. Both the electrical and thermal transport properties in this system were found to decrease with a lower VEC number. Overall, the large microstructural complexity and lower average VEC in these types of alloys can potentially be used to lower both the total and the lattice thermal conductivity. These findings highlight the possibility to exploit HEAs as a new class of future high temperature TE materials.

  20. Modeling quantum fluid dynamics at nonzero temperatures

    Science.gov (United States)

    Berloff, Natalia G.; Brachet, Marc; Proukakis, Nick P.

    2014-03-01

    The detailed understanding of the intricate dynamics of quantum fluids, in particular in the rapidly growing subfield of quantum turbulence which elucidates the evolution of a vortex tangle in a superfluid, requires an in-depth understanding of the role of finite temperature in such systems. The Landau two-fluid model is the most successful hydrodynamical theory of superfluid helium, but by the nature of the scale separations it cannot give an adequate description of the processes involving vortex dynamics and interactions. In our contribution we introduce a framework based on a nonlinear classical-field equation that is mathematically identical to the Landau model and provides a mechanism for severing and coalescence of vortex lines, so that the questions related to the behavior of quantized vortices can be addressed self-consistently. The correct equation of state as well as nonlocality of interactions that leads to the existence of the roton minimum can also be introduced in such description. We review and apply the ideas developed for finite-temperature description of weakly interacting Bose gases as possible extensions and numerical refinements of the proposed method. We apply this method to elucidate the behavior of the vortices during expansion and contraction following the change in applied pressure. We show that at low temperatures, during the contraction of the vortex core as the negative pressure grows back to positive values, the vortex line density grows through a mechanism of vortex multiplication. This mechanism is suppressed at high temperatures.

  1. Analytical modelling of temperature effects on synapses

    CERN Document Server

    Kufel, Dominik S

    2016-01-01

    It was previously reported, that temperature may significantly influence neural dynamics on different levels of brain modelling. Due to this fact, while creating the model in computational neuroscience we would like to make it scalable for wide-range of various brain temperatures. However currently, because of a lack of experimental data and an absence of analytical model describing temperature influence on synapses, it is not possible to include temperature effects on multi-neuron modelling level. In this paper, we propose first step to deal with this problem: new analytical model of AMPA-type synaptic conductance, which is able to include temperature effects in low-frequency stimulations. It was constructed on basis of Markov model description of AMPA receptor kinetics and few simplifications motivated both experimentally and from Monte Carlo simulation of synaptic transmission. The model may be used for efficient and accurate implementation of temperature effects on AMPA receptor conductance in large scale...

  2. High-temperature superconducting conductors and cables

    Energy Technology Data Exchange (ETDEWEB)

    Peterson, D.E.; Maley, M.P.; Boulaevskii, L.; Willis, J.O.; Coulter, J.Y.; Ullmann, J.L.; Cho, Jin; Fleshler, S.

    1996-09-01

    This is the final report of a 3-year LDRD project at LANL. High-temperature superconductivity (HTS) promises more efficient and powerful electrical devices such as motors, generators, and power transmission cables; however this depends on developing HTS conductors that sustain high current densities J{sub c} in high magnetic fields at temperatures near liq. N2`s bp. Our early work concentrated on Cu oxides but at present, long wire and tape conductors can be best made from BSCCO compounds with high J{sub c} at low temperatures, but which are degraded severely at temperatures of interest. This problem is associated with thermally activated motion of magnetic flux lines in BSCCO. Reducing these dc losses at higher temperatures will require a high density of microscopic defects that will pin flux lines and inhibit their motion. Recently it was shown that optimum defects can be produced by small tracks formed by passage of energetic heavy ions. Such defects result when Bi is bombarded with high energy protons. The longer range of protons in matter suggests the possibility of application to tape conductors. AC losses are a major limitation in many applications of superconductivity such as power transmission. The improved pinning of flux lines reduces ac losses, but optimization also involves other factors. Measuring and characterizing these losses with respect to material parameters and conductor design is essential to successful development of ac devices.

  3. High temperature superconductivity induced by incipient magnetism

    Science.gov (United States)

    Weger, M.; Pereg, Y.

    1990-10-01

    We consider the BCS gap equation, with an attractive interaction λ with an upper cutoff ω 0 and lower cutoff ω 1, and a repulsive interaction μ with cutoffΓ. We consider parameters such that a superconducting solution does not exist. We add a repulsive interaction ν eith cutoff ω1 ( ω1 < ω0), and show that this repulsive interaction (that we attribute to incipient magnetism) induces a superconducting state possessing a high transition temperature. In this state, the gap function Δ(ɛ) oscillates as function of ɛ, with a period of order ω 0. We also find solutions antisymmetric in energy [ Δ( ɛ) = - Δ(- ɛ) ], which turn out to be almost degenerate with the normal, symmetric ones. We discuss the physical implications of this model. Our model thus combines a low frequency repulsion due to antiferromagnetic interactions, with excitonic attraction at intermediate frequencies, and ordinary Coulomb repulsion above that. All frequency ranges, and coupling strengths, are comparable with the bandwidth.

  4. Electronic phase separation and high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Kivelson, S.A. [Univ. of California, Los Angeles, CA (United States). Dept. of Physics; Emery, V.J. [Brookhaven National Lab., Upton, NY (United States)

    1994-01-11

    The authors review the extensive evidence from model calculations that neutral holes in an antiferromagnet separate into hole-rich and hole-poor phases. All known solvable limits of models of holes in a Heisenberg antiferromagnet exhibit this behavior. The authors show that when the phase separation is frustrated by the introduction of long-range Coulomb interactions, the typical consequence is either a modulated (charge density wave) state or a superconducting phase. The authors then review some of the strong experimental evidence supporting an electronically-driven phase separation of the holes in the cuprate superconductors and the related Ni oxides. Finally, the authors argue that frustrated phase separation in these materials can account for many of the anomalous normal state properties of the high temperature superconductors and provide the mechanism of superconductivity. In particular, it is shown that the T-linear resistivity of the normal state is a paraconductivity associated with a novel composite pairing, although the ordered superconducting state is more conventional.

  5. 皮肤表面热烧伤温度场的数值模拟%Numerical modeling of a temperature field on the surface of skin tissues exposed to high temperature

    Institute of Scientific and Technical Information of China (English)

    朱晓明; 胡志刚; 刘竞达

    2015-01-01

    背景:研究认为当生物组织的温度高于44℃时会发生热损伤,准确地预测烧伤范围,可以为烧伤的诊断和治疗提供很大帮助。目的:建立皮肤组织热烧伤的数学模型,分析烧伤过程中的温度变化规律,预测其烧伤范围。方法:建立皮肤有限元模型,对皮肤组织在烧伤过程中的温度场进行数值模拟,得出了皮肤组织的瞬态温度分布,同时用新鲜带皮猪肉进行了烧伤后温度测量实验,将数值计算结果与实验结果进行对比。结果与结论:利用有限元法分析得出皮肤组织的温度分布情况,发现理论数值和实验数值温度变化趋势基本一致,但并未完全重合。提示该有限元模型可以用来预测皮肤组织的烧伤范围。%BACKGROUND:Researchers suggest that thermal damage happens when the temperature of biological tissues is over 44℃. Accurate analysis of burn range wil facilitate diagnosis and therapy of skin burns. OBJECTIVE: To establish the mathematical model of the skin tissues subjected to high temperature and to analyze heat transfer process, and then to predict the burn range of the skin. METHODS:A finite element method was used to simulate the temperature field when the skin tissue was burned. And the relevant animal experiment was conducted to identify the mathematical model. RESULTS AND CONCLUSION:The temperature field was obtained by using the finite element method and the variation tendency between the theoretical data and the experimental data were agreed, but they did not fuly coincide. The scope of skin burn can be predicted by the present finite element method, and help to research the process of heat transfer.

  6. High Temperature Integrated Thermoelectric Ststem and Materials

    Energy Technology Data Exchange (ETDEWEB)

    Mike S. H. Chu

    2011-06-06

    The final goal of this project is to produce, by the end of Phase II, an all ceramic high temperature thermoelectric module. Such a module design integrates oxide ceramic n-type, oxide ceramic p-type materials as thermoelectric legs and oxide ceramic conductive material as metalizing connection between n-type and p-type legs. The benefits of this all ceramic module are that it can function at higher temperatures (> 700 C), it is mechanically and functionally more reliable and it can be scaled up to production at lower cost. With this all ceramic module, millions of dollars in savings or in new opportunities recovering waste heat from high temperature processes could be made available. A very attractive application will be to convert exhaust heat from a vehicle to reusable electric energy by a thermoelectric generator (TEG). Phase I activities were focused on evaluating potential n-type and p-type oxide compositions as the thermoelectric legs. More than 40 oxide ceramic powder compositions were made and studied in the laboratory. The compositions were divided into 6 groups representing different material systems. Basic ceramic properties and thermoelectric properties of discs sintered from these powders were measured. Powders with different particles sizes were made to evaluate the effects of particle size reduction on thermoelectric properties. Several powders were submitted to a leading thermoelectric company for complete thermoelectric evaluation. Initial evaluation showed that when samples were sintered by conventional method, they had reasonable values of Seebeck coefficient but very low values of electrical conductivity. Therefore, their power factors (PF) and figure of merits (ZT) were too low to be useful for high temperature thermoelectric applications. An unconventional sintering method, Spark Plasma Sintering (SPS) was determined to produce better thermoelectric properties. Particle size reduction of powders also was found to have some positive benefits

  7. Predicting Grain Growth in Nanocrystalline Materials: A Thermodynamic and Kinetic-Based Model Informed by High Temperature X-ray Diffraction Experiments

    Science.gov (United States)

    2014-10-01

    Predicting grain growth in nanocrystalline materials requires modeling approaches that incorporate grain boundary thermodynamics and kinetics. In...growth in nanocrystalline materials and this extended model can be applied to understanding how grain size evolves with temperature in other nanocrystalline systems....this work, a thermokinetic model for grain growth was applied to experimental X-ray diffraction measurements from nanocrystalline Fe Zr in an effort 1

  8. High Temperature VARTM of Phenylethynyl Terminated Imides

    Science.gov (United States)

    Ghose, Sayata; Watson, Kent A.; Cano, Roberto J.; Britton, Sean M.; Jensen, Brian J.; Connell, John W.; Herring, Helen M.; Linberry, Quentin J.

    2009-01-01

    LaRC phenylethynyl terminated imide (PETI) resins were processed into composites using high temperature vacuum assisted resin transfer molding (VARTM). Although initial runs yielded composites with high void content, process modifications reduced voids to <3%. Photomicrographs were taken and void contents and T(sub g)s of the panels were determined.

  9. Reactive Plasticizers for High Temperature Quinoxaline Thermoplastics

    Science.gov (United States)

    1976-06-01

    involves essentially two steps, consolidation of boardy prepreg into sheet stock and thermoforming the sheet stock into structural components. A...problem associated with the fabrication process is the high temperatures required in both the consolidation and thermoforming operations. High processing

  10. Temperature dependence of electronic heat capacity in Holstein model

    CERN Document Server

    Fialko, N S; Lakhno, V D

    2015-01-01

    The dynamics of charge migration was modeled to calculate temperature dependencies of its thermodynamic equilibrium values such as energy and electronic heat capacity in homogeneous adenine fragments. The energy varies from nearly polaron one at T~0 to midpoint of the conductivity band at high temperatures. The peak on the graph of electronic heat capacity is observed at the polaron decay temperature.

  11. A Conceptual Model to Link Anomalously High Temperature Gradients in the Cerros del Rio Volcanic Field to Regional Flow in the Espanola Basin, New Mexico

    Science.gov (United States)

    Fillingham, E. J.; Keller, S. N.; McCullough, K. R.; Watters, J.; Weitering, B.; Wilce, A. M.; Folsom, M.; Kelley, S.; Pellerin, L.

    2015-12-01

    proposed conceptual model of the regional flow system in the Espanola Basin addresses the anomalously high geothermal gradients in the monitoring wells in and near the Cerros del Rio volcanic field in addition to the recovering water levels in the Buckman well field.

  12. A coupled model between mechanical deformation and chemical diffusion: An explanation for the preservation of chemical zonation in plagioclase at high temperatures

    Science.gov (United States)

    Zhong, Xin; Vrijmoed, Johannes; Moulas, Evangelos; Tajcmanová, Lucie

    2016-04-01

    Compositional zoning in metamorphic minerals have been generally recognized as an important geological feature to decipher the metamorphic history of rocks. The observed chemical zoning of, e.g. garnet, is commonly interpreted as disequilibrium between the fractionated inner core and the surrounding matrix. However, chemically zoned minerals were also observed in high grade rocks (T>800 degree C) where the duration of metamorphic processes was independently dated to take several Ma. This implies that temperature may not be the only factor that controls diffusion timescales, and grain scale pressure variation was proposed to be a complementary factor that may significantly contribute to the formation and preservation of chemical zoning in high temperature metamorphic minerals [Tajcmanová 2013, 2015]. Here, a coupled model is developed to simulate viscous deformation and chemical diffusion. The numerical approach considers the conservation of mass, momentum, and a constitutive relation developed from equilibrium thermodynamics. A compressible viscoelastic rheology is applied, which associates the volumetric change triggered by deformation and diffusion to a change of pressure. The numerical model is applied to the chemically zoned plagioclase rim described by [Tajcmanová 2014]. The diffusion process operating during the plagioclase rim formation can lead to a development of a pressure gradient. Such a pressure gradient, if maintained during ongoing viscous relaxation, can lead to the preservation of the observed chemical zonation in minerals. An important dimensionless number, the Deborah number, is defined as the ratio between the Maxwell viscoelastic relaxation time and the characteristic diffusion time. It characterizes the relative influence between the maintenance of grain scale pressure variation and chemical diffusion. Two extreme regimes are shown: the mechanically-controlled regime (high Deborah number) and diffusion-controlled regime (low Deborah number

  13. A nonlinear multi-proxy model based on manifold learning to reconstruct water temperature from high resolution trace element profiles in biogenic carbonates

    Directory of Open Access Journals (Sweden)

    M. Bauwens

    2010-11-01

    Full Text Available A long standing problem in paleoceanography concerns the reconstruction of water temperature from δ18O carbonate. It is problematic in the case of freshwater influenced environments because the δ18O isotopic composition of the ambient water (related to salinity needs to be known. In this paper we argue for the use of a nonlinear multi-proxy method called Weight Determination by Manifold Regularization (WDMR to develop a temperature reconstruction model that is less sensitive to salinity variations. The motivation for using this type of model is twofold: firstly, observed nonlinear relations between specific proxies and water temperature motivate the use of nonlinear models. Secondly, the use of multi-proxy models enables salinity related variations of a given temperature proxy to be explained by salinity-related information carried by a separate proxy. Our findings confirm that Mg/Ca is a powerful paleothermometer and highlight that reconstruction performance based on this proxy is improved significantly by combining its information with the information for other trace elements in multi-proxy models. Although the models presented here are black-box models that do not use any prior knowledge about the proxies, the comparison of model reconstruction performances based on different proxy combinations do yield useful information about proxy characteristics. Using Mg/Ca, Sr/Ca, Ba/Ca and Pb/Ca the WDMR model enables a temperature reconstruction with a root mean squared error of ± 2.19 °C for a salinity range between 15 and 32.

  14. Universal properties of high-temperature superconductors from real-space pairing: t -J -U model and its quantitative comparison with experiment

    Science.gov (United States)

    Spałek, Józef; Zegrodnik, Michał; Kaczmarczyk, Jan

    2017-01-01

    Selected universal experimental properties of high-temperature superconducting (HTS) cuprates have been singled out in the last decade. One of the pivotal challenges in this field is the designation of a consistent interpretation framework within which we can describe quantitatively the universal features of those systems. Here we analyze in a detailed manner the principal experimental data and compare them quantitatively with the approach based on a single-band model of strongly correlated electrons supplemented with strong antiferromagnetic (super)exchange interaction (the so-called t -J -U model). The model rationale is provided by estimating its microscopic parameters on the basis of the three-band approach for the Cu-O plane. We use our original full Gutzwiller wave-function solution by going beyond the renormalized mean-field theory (RMFT) in a systematic manner. Our approach reproduces very well the observed hole doping (δ ) dependence of the kinetic-energy gain in the superconducting phase, one of the principal non-Bardeen-Cooper-Schrieffer features of the cuprates. The calculated Fermi velocity in the nodal direction is practically δ -independent and its universal value agrees very well with that determined experimentally. Also, a weak doping dependence of the Fermi wave vector leads to an almost constant value of the effective mass in a pure superconducting phase which is both observed in experiment and reproduced within our approach. An assessment of the currently used models (t -J , Hubbard) is carried out and the results of the canonical RMFT as a zeroth-order solution are provided for comparison to illustrate the necessity of the introduced higher-order contributions.

  15. Experimental Validation of Passive Safety System Models: Application to Design and Optimization of Fluoride-Salt-Cooled, High-Temperature Reactors

    Science.gov (United States)

    Zweibaum, Nicolas

    The development of advanced nuclear reactor technology requires understanding of complex, integrated systems that exhibit novel phenomenology under normal and accident conditions. The advent of passive safety systems and enhanced modular construction methods requires the development and use of new frameworks to predict the behavior of advanced nuclear reactors, both from a safety standpoint and from an environmental impact perspective. This dissertation introduces such frameworks for scaling of integral effects tests for natural circulation in fluoride-salt-cooled, high-temperature reactors (FHRs) to validate evaluation models (EMs) for system behavior; subsequent reliability assessment of passive, natural- circulation-driven decay heat removal systems, using these validated models; evaluation of life cycle carbon dioxide emissions as a key environmental impact metric; and recommendations for further work to apply these frameworks in the development and optimization of advanced nuclear reactor designs. In this study, the developed frameworks are applied to the analysis of the Mark 1 pebble-bed FHR (Mk1 PB-FHR) under current investigation at the University of California, Berkeley (UCB). (Abstract shortened by UMI.).

  16. Modeling the effect in of criticality from changes in key parameters for small High Temperature Nuclear Reactor (U-BatteryTM) using MCNP4C

    Science.gov (United States)

    Pauzi, A. M.

    2013-06-01

    The neutron transport code, Monte Carlo N-Particle (MCNP) which was wellkown as the gold standard in predicting nuclear reaction was used to model the small nuclear reactor core called "U-batteryTM", which was develop by the University of Manchester and Delft Institute of Technology. The paper introduces on the concept of modeling the small reactor core, a high temperature reactor (HTR) type with small coated TRISO fuel particle in graphite matrix using the MCNPv4C software. The criticality of the core were calculated using the software and analysed by changing key parameters such coolant type, fuel type and enrichment levels, cladding materials, and control rod type. The criticality results from the simulation were validated using the SCALE 5.1 software by [1] M Ding and J L Kloosterman, 2010. The data produced from these analyses would be used as part of the process of proposing initial core layout and a provisional list of materials for newly design reactor core. In the future, the criticality study would be continued with different core configurations and geometries.

  17. Development of models and online diagnostic monitors of the high-temperature corrosion of refractories in oxy/fuel glass furnaces : final project report.

    Energy Technology Data Exchange (ETDEWEB)

    Griffiths, Stewart K.; Gupta, Amul (Monofrax Inc., Falconer, NY); Walsh, Peter M.; Rice, Steven F.; Velez, Mariano (University of Missouri, Rolla, MO); Allendorf, Mark D.; Pecoraro, George A. (PPG Industries, Inc., Pittsburgh, PA); Nilson, Robert H.; Wolfe, H. Edward (ANH Refractories, Pittsburgh, PA); Yang, Nancy Y. C.; Bugeat, Benjamin () American Air Liquide, Countryside, IL); Spear, Karl E. (Pennsylvania State University, University Park, PA); Marin, Ovidiu () American Air Liquide, Countryside, IL); Ghani, M. Usman (American Air Liquide, Countryside, IL)

    2005-02-01

    This report summarizes the results of a five-year effort to understand the mechanisms and develop models that predict the corrosion of refractories in oxygen-fuel glass-melting furnaces. Thermodynamic data for the Si-O-(Na or K) and Al-O-(Na or K) systems are reported, allowing equilibrium calculations to be performed to evaluate corrosion of silica- and alumina-based refractories under typical furnace operating conditions. A detailed analysis of processes contributing to corrosion is also presented. Using this analysis, a model of the corrosion process was developed and used to predict corrosion rates in an actual industrial glass furnace. The rate-limiting process is most likely the transport of NaOH(gas) through the mass-transport boundary layer from the furnace atmosphere to the crown surface. Corrosion rates predicted on this basis are in better agreement with observation than those produced by any other mechanism, although the absolute values are highly sensitive to the crown temperature and the NaOH(gas) concentration at equilibrium and at the edge of the boundary layer. Finally, the project explored the development of excimer laser induced fragmentation (ELIF) fluorescence spectroscopy for the detection of gas-phase alkali hydroxides (e.g., NaOH) that are predicted to be the key species causing accelerated corrosion in these furnaces. The development of ELIF and the construction of field-portable instrumentation for glass furnace applications are reported and the method is shown to be effective in industrial settings.

  18. Ultra High Temperature Ceramics for aerospace applications

    OpenAIRE

    Jankowiak, A.; Justin, J.F.

    2014-01-01

    Après relecture une erreur est apparue dans le document et doit être retiré; International audience; The Ultra High Temperature Ceramics (UHTCs) are of great interest for different engineering sectors and notably the aerospace industry. Indeed, hypersonic flights, re-entry vehicles, propulsion applications and so on, require new materials that can perform in oxidizing or corrosive atmospheres at temperatures higher than 2000°C and sometimes, for long life-time. To fulfil these requirements, U...

  19. Effects of High Temperature on Collector Coatings

    Science.gov (United States)

    Lowery, J. R.

    1982-01-01

    Report reveals electroplated black chrome is good coating for concentrating collectors in which temperatures are in the 650 degrees-800 degrees F (340 degrees - 430 degrees C) range. Black chrome thermal emittance is low and solar-absorption properties are not seriously degraded at high temperatures. Black coatings are used to increase absorption of solar energy by base metal while decreasing emission of infrared energy. Coatings are intended to improve efficiency of solar collectors.

  20. Low Temperature Heating and High Temperature Cooling in Buildings

    DEFF Research Database (Denmark)

    Kazanci, Ongun Berk

    , a single-family house designed for plus-energy targets and equipped with a radiant water-based floor heating and cooling system was studied by means of full-scale measurements, dynamic building simulations and thermodynamic evaluation tools. Thermal indoor environment and energy performance of the house...... performance of heating and cooling systems for achieving the same thermal indoor environment. The results show that it is crucial to minimize the heating and cooling demands in the design phase since these demands determine the terminal units and heat sources and sinks that could be used. Low temperature...... heating and high temperature cooling systems (a radiant water-based floor heating and cooling system in this study) proved to be superior to compared systems, evaluated with different system analysis tools; energy, exergy, and entransy. Radiant systems should be coupled to appropriate heating and cooling...

  1. Topological susceptibility at high temperature on the lattice

    CERN Document Server

    Frison, J; Matsufuru, H; Mori, S; Yamada, N

    2016-01-01

    QCD topological susceptibility at high temperature, $\\chi_t(T)$, provides an important input for the estimate of the axion abundance in the present Universe. While the model independent determination of $\\chi_t(T)$ should be possible from the first principles using lattice QCD, existing methods fail at high temperature, since not only the probability that non-trivial topological sectors appear in the configuration generation process but also the local topological fluctuations get strongly suppressed. We propose a novel method to calculate the temperature dependence of topological susceptibility at high temperature. A feasibility test is performed on a small lattice in the quenched approximation, and the results are compared with the prediction of the dilute instanton gas approximation. It is found that the method works well especially at very high temperature and the result is consistent with the instanton calculus down to $T\\sim 2\\, T_c$ within the statistical uncertainty.

  2. Topological susceptibility at high temperature on the lattice

    Science.gov (United States)

    Frison, J.; Kitano, R.; Matsufuru, H.; Mori, S.; Yamada, N.

    2016-09-01

    QCD topological susceptibility at high temperature, χ t ( T ), provides an important input for the estimate of the axion abundance in the present Universe. While the model independent determination of χ t ( T ) should be possible from the first principles using lattice QCD, existing methods fail at high temperature, since not only the probability that non-trivial topological sectors appear in the configuration generation process but also the local topological fluctuations get strongly suppressed. We propose a novel method to calculate the temperature dependence of topological susceptibility at high temperature. A feasibility test is performed on a small lattice in the quenched approximation, and the results are compared with the prediction of the dilute instanton gas approximation. It is found that the method works well especially at very high temperature and the result is consistent with the instanton calculus down to T ˜ 2 T c within the statistical uncertainty.

  3. High temperature gas dynamics an introduction for physicists and engineers

    CERN Document Server

    Bose, Tarit K

    2014-01-01

    High Temperature Gas Dynamics is a primer for scientists, engineers, and students who would like to have a basic understanding of the physics and the behavior of high-temperature gases. It is a valuable tool for astrophysicists as well. The first chapters treat the basic principles of quantum and statistical mechanics and how to derive thermophysical properties from them. Special topics are included that are rarely found in other textbooks, such as the thermophysical and transport properties of multi-temperature gases and a novel method to compute radiative transfer. Furthermore, collision processes between different particles are discussed. Separate chapters deal with the production of high-temperature gases and with electrical emission in plasmas, as well as related diagnostic techniques.This new edition adds over 100 pages and includes the following updates: several sections on radiative properties of high temperature gases and various radiation models, a section on shocks in magneto-gas-dynamics, a sectio...

  4. Dielectric Properties of Yttria Ceramics at High Temperature

    Institute of Scientific and Technical Information of China (English)

    Jian Chen; Zheng-Ping Gao; Jin-Ming Wang; Da-Hai Zhang

    2007-01-01

    Based on Clausius-Mosotti equation and Debye relaxation theory, the dielectric model of yttria ceramics was developed according to the dielectric loss mechanism. The dielectric properties of yttria ceramics were predicted at high temperature. The temperature dependence and frequency dependence of dielectric constant and dielectric loss were discussed, respectively.As the result, the data calculated by theoretical dielectric model are in agreement with experimental data.

  5. Micro-mechanical modeling of the growth/percolation of pressurized pores in a ceramic matrix at high temperatures; Modelisation micromecanique de la croissance et de la percolation de pores sous pression dans une matrice ceramique a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Vincent, P.G

    2007-11-15

    The aim of this work is to propose an elasto-plastic model of damage in a porous ceramics containing two populations of saturated cavities: the nuclear fuel uranium dioxide highly irradiated and at high temperature. The followed approach consists in a multi-scale approach based on the hypothesis of separation of the scales between the two populations of cavities (spherical intragranular pores and spheroidal intergranular pores) and of those of the macroscopic isotropy. The proposed elasto-plastic model of damage treats separately of the elasticity, of the surface of plasticity and of the evolution of the internal parameters of the model with load. The taking into account of different pressures in each population of cavity is carried out for elasticity-plasticity-damage. The model developed for the elastic behaviour takes into account the two populations of cavity, their morphology, their distribution and the pore pressures inside them. The proposed plasticity criteria is based on homogenization methods for non linear behaviours. At the grain scale, the first population of cavity is taken into account by a plasticity criteria of Gurson-Tvegaard-Needleman type. At the scale of grains collection, the presence of a second population of cavity inside a compressible matrix leads to the development of new superior boundaries and pertaining estimations for the effective plasticity surface. These models depend on the morphology and of the distribution of cavities. In the case of drained cavities, an analytical estimation, based on the writing of the classical variational principle with a compressible velocity field and an average on the equiprobable orientations is developed. In the case of saturated cavity, another estimation, based on the variational approach of Ponte Castaneda (1991) with a linear N phases comparison composite is proposed. These models are compared to numerical simulations by finite elements and to numerical simulations using the fast Fourier

  6. Experimental demonstration of vortex pancake in high temperature superconductor

    Institute of Scientific and Technical Information of China (English)

    WANG Wei-xian; ZHANG Yu-heng

    2006-01-01

    In order to demonstrate the existence of the vortex pancake in high temperature superconductor experimentally,a configuration in which the current and voltage electrodes lies separately on the top and bottom surface is used.The E-j relation obtained with this electrodes spatial configuration is different from the expected E-j behavior of the stiff vortex line model.Thus,the current results support the existence of the vortex pancake in high temperature superconductor.

  7. Geochemistry of Aluminum in High Temperature Brines

    Energy Technology Data Exchange (ETDEWEB)

    Benezeth, P.; Palmer, D.A.; Wesolowski, D.J.

    1999-05-18

    The objective ofthis research is to provide quantitative data on the equilibrium and thermodynamic properties of aluminum minerals required to model changes in permeability and brine chemistry associated with fluid/rock interactions in the recharge, reservoir, and discharge zones of active geothermal systems. This requires a precise knowledge of the thermodynamics and speciation of aluminum in aqueous brines, spanning the temperature and fluid composition rangesencountered in active systems. The empirical and semi-empirical treatments of the solubility/hydrolysis experimental results on single aluminum mineral phases form the basis for the ultimate investigation of the behavior of complex aluminosilicate minerals. The principal objective in FY 1998 was to complete the solubility measurements on boehmite (AIOOH) inNaC1 media( 1 .O and 5.0 molal ionic strength, IOO-250°C). However, additional measurements were also made on boehmite solubility in pure NaOH solutions in order to bolster the database for fitting in-house isopiestic data on this system. Preliminary kinetic Measurements of the dissolution/precipitation of boehmite was also carried out, although these were also not planned in the earlier objective. The 1999 objectives are to incorporate these treatments into existing codes used by the geothermal industry to predict the chemistry ofthe reservoirs; these calculations will be tested for reliability against our laboratory results and field observations. Moreover, based on the success of the experimental methods developed in this program, we intend to use our unique high temperature pH easurement capabilities to make kinetic and equilibrium studies of pH-dependent aluminosilicate transformation reactions and other pH-dependent heterogeneous reactions.

  8. Joining of ultra-high temperature ceramics

    OpenAIRE

    Silvestroni, Laura; Sciti, Diletta; Esposito, Laura; Glaeser, Andreas

    2012-01-01

    In the last decade, ultra-high temperature ceramics raised renewed interest after the first studies in the 60's. Thanks to their high melting point, superior to any group of materials, and to their set of interesting physical and engineering properties, they find application in aerospace industry, propulsion field, as cladding materials in generation IV nuclear reactors and solar absorbers in novel HT CSP systems. Recent efforts were devoted to the achievement of high strength and toughness m...

  9. Low toxicity high temperature PMR polyimide

    Science.gov (United States)

    Pater, Ruth H. (Inventor)

    1992-01-01

    In-situ polymerization of monomer reactants (PMR) type polyimides constitute an important class of ultra high performance composite matrix resins. PMR-15 is the best known and most widely used PMR polyimide. An object of the present invention is to provide a substantially improved high temperature PMR-15 system that exhibits better processability, toughness, and thermo-oxidative stability than PMR-15, as well as having a low toxicity. Another object is to provide new PMR polyimides that are useful as adhesives, moldings, and composite matrices. By the present invention, a new PMR polyimide comprises a mixture of the following compounds: 3,4'-oxydianiline (3,4'-ODA), NE, and BTDE which are then treated with heat. This PMR was designated LaRC-RP46 and has a broader processing window, better reproducibility of high quality composite parts, better elevated temperature mechanical properties, and higher retention of mechanical properties at an elevated temperature, particularly, at 371 C.

  10. High temperature superconductivity the road to higher critical temperature

    CERN Document Server

    Uchida, Shin-ichi

    2015-01-01

    This book presents an overview of material-specific factors that influence Tc and give rise to diverse Tc values for copper oxides and iron-based high- Tc superconductors on the basis of more than 25 years of experimental data, to most of which the author has made important contributions. The book then explains why both compounds are distinct from others with similar crystal structure and whether or not one can enhance Tc, which in turn gives a hint on the unresolved pairing mechanism. This is an unprecedented new approach to the problem of high-temperature superconductivity and thus will be inspiring to both specialists and non-specialists interested in this field.   Readers will receive in-depth information on the past, present, and future of high-temperature superconductors, along with special, updated information on what the real highest Tc values are and particularly on the possibility of enhancing Tc for each member material, which is important for application. At this time, the highest Tc has not been...

  11. High temperature and pressure alkaline electrolysis

    DEFF Research Database (Denmark)

    Allebrod, Frank; Chatzichristodoulou, Christodoulos; Mogensen, Mogens Bjerg

    2013-01-01

    and pressures. Two measurement systems were built to perform measurements under high pressures and at elevated temperatures of up to 95 bar and 250 °C, respectively. The conductivity of aqueous KOH and aqueous KOH immobilized in a porous SrTiO3 structure were investigated at elevated temperatures and high...... the operational temperature and pressure to produce pressurized hydrogen at high rate (m3 H2·h-1·m-2 cell area) and high electrical efficiency. This work describes an exploratory technical study of the possibility to produce hydrogen and oxygen with a new type of alkaline electrolysis cell at high temperatures...... concentrations of the electrolyte using the van der Pauw method in combination with electrochemical impedance spectroscopy (EIS). Conductivity values as high as 2.9 S cm-1 for 45 wt% KOH aqueous KOH and 0.84 S cm-1 for the immobilized KOH of the same concentration were measured at 200 °C. Porous SrTiO3 was used...

  12. NOVEL REFRACTORY MATERIALS FOR HIGH ALKALI, HIGH TEMPERATURE ENVIRONMENTS

    Energy Technology Data Exchange (ETDEWEB)

    Hemrick, James Gordon [ORNL; Smith, Jeffrey D [ORNL; O' Hara, Kelley [University of Missouri, Rolla; Rodrigues-Schroer, Angela [Minteq International, Inc.; Colavito, [Minteq International, Inc.

    2012-08-01

    A project was led by Oak Ridge National Laboratory (ORNL) in collaboration with a research team comprised of the academic institution Missouri University of Science and Technology (MS&T), and the industrial company MINTEQ International, Inc. (MINTEQ), along with representatives from the aluminum, chemical, glass, and forest products industries. The project was to address the need for new innovative refractory compositions by developing a family of novel MgO-Al 2O3, MgAl2O4, or other similar spinel structured or alumina-based unshaped refractory compositions (castables, gunnables, shotcretes, etc.) utilizing new aggregate materials, bond systems, protective coatings, and phase formation techniques (in-situ phase formation, altered conversion temperatures, accelerated reactions, etc). This family of refractory compositions would then be tailored for use in high-temperature, high-alkaline industrial environments like those found in the aluminum, chemical, forest products, glass, and steel industries. Both practical refractory development experience and computer modeling techniques were used to aid in the design of this new family of materials. The newly developed materials were expected to offer alternative material choices for high-temperature, high-alkali environments that were capable of operating at higher temperatures (goal of increasing operating temperature by 100-200oC depending on process) or for longer periods of time (goal of twice the life span of current materials or next process determined service increment). This would lead to less process down time, greater energy efficiency for associated manufacturing processes (more heat kept in process), and materials that could be installed/repaired in a more efficient manner. The overall project goal was a 5% improvement in energy efficiency (brought about through a 20% improvement in thermal efficiency) resulting in a savings of 3.7 TBtu/yr (7.2 billion ft3 natural gas) by the year 2030. Additionally, new

  13. Materials corrosion and protection at high temperatures; Corrosion et protection des materiaux a haute temperature

    Energy Technology Data Exchange (ETDEWEB)

    Balbaud, F.; Desgranges, Clara; Martinelli, Laure; Rouillard, Fabien [CEA-Saclay, DEN, DPC, SCCME, Laboratoire d' Etude de la Corrosion Non Aqueuse, 91191 Gif-sur-Yvette Cedex (France); Duhamel, Cecile [Mines ParisTech, Centre des materiaux UMR-CNRS 7633, BP 87, 91003 Evry Cedex (France); Marchetti, Loic; Perrin, Stephane [CEA, Laboratoire d' Etude de la Corrosion Aqueuse (France); Molins, Regine [Mines ParisTech, Direction de la Recherche, 60 Bvd Saint Michel, 75272 Paris Cedex 06 (France); Chevalier, S.; Heintz, O. [Laboratoire interdisciplinaire Carnot de Bourgogne, UMR 5209 CNRS, Univ. de Bourgogne, Dijon (France); David, N.; Fiorani, J.M.; Vilasi, M. [Institut Jean Lamour, UMR 7198, Univ. Henri Poincare Nancy-1 - CNRS, 54506 Vandoeuvre-les-Nancy (France); Wouters, Y.; Galerie, A. [SIMAP UMR CNRS 5266, Grenoble-INP/UJF, 1130 rue de la Piscine BP 75, 38402 Saint-Martin-d' Heres Cedex (France); Mangelinck, D. [IM2NP, UMR6242, CNRS, Univ. Paul Cezanne, Case 142, Faculte de Saint Jerome, 13397 Marseille Cedex 20 (France); Viguier, B.; Monceau, D. [Univ. de Toulouse, Institut Carnot CIRIMAT, INP-ENSIACET, 4 allee Emile Monso, BP 44362, 31030 Toulouse Cedex 4 (France); Soustelle, M. [Ecole nationale superieure des mines, Saint Etienne (France); Pijolat, M. [Centre Spin, Ecole des mines de Saint Etienne (France); Favergeon, J.; Brancherie, D.; Moulin, G.; Dawi, K. [Laboratoire Roberval, UTC (France); Wolski, K.; Barnier, V. [Centre SMS, EMSE, UMR 5146, LCG, Univ. de Lyon, 158 Cours Fauriel, 42023 Saint Etienne (France); Rebillat, F. [LCTS, Univ. de Bordeaux (France); Lavigne, O. [Onera, Dep. Materiaux et Structures Metalliques, BP 72, 29 av. de la Division Leclerc, 92322 Chatillon (France); Brossard, J.M. [Dep. energetique et procedes, Veolia Environnement Recherche et Innovation, Limay (France); Ropital, F. [IFP Energies Nouvelles, BP 3, 69360 Solaize (France); Mougin, J. [CEA-Liten, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France)

    2011-07-01

    This book was made from the lectures given in 2010 at the thematic school on 'materials corrosion and protection at high temperatures'. It gathers the contributions from scientists and engineers coming from various communities and presents a state-of-the-art of the scientific and technological developments concerning the behaviour of materials at high temperature, in aggressive environments and in various domains (aerospace, nuclear, energy valorization, and chemical industries). It supplies pedagogical tools to grasp high temperature corrosion thanks to the understanding of oxidation mechanisms. It proposes some protection solutions for materials and structures. Content: 1 - corrosion costs; macro-economical and metallurgical approach; 2 - basic concepts of thermo-chemistry; 3 - introduction to the Calphad (calculation of phase diagrams) method; 4 - use of the thermodynamic tool: application to pack-cementation; 5 - elements of crystallography and of real solids description; 6 - diffusion in solids; 7 - notions of mechanics inside crystals; 8 - high temperature corrosion: phenomena, models, simulations; 9 - pseudo-stationary regime in heterogeneous kinetics; 10 - nucleation, growth and kinetic models; 11 - test experiments in heterogeneous kinetics; 12 - mechanical aspects of metal/oxide systems; 13 - coupling phenomena in high temperature oxidation; 14 - other corrosion types; 15 - methods of oxidized surfaces analysis at micro- and nano-scales; 16 - use of SIMS in the study of high temperature corrosion of metals and alloys; 17 - oxidation of ceramics and of ceramic matrix composite materials; 18 - protective coatings against corrosion and oxidation; 19 - high temperature corrosion in the 4. generation of nuclear reactor systems; 20 - heat exchangers corrosion in municipal waste energy valorization facilities; 21 - high temperature corrosion in oil refining and petrochemistry; 22 - high temperature corrosion in new energies industry. (J.S.)

  14. Materials for high-temperature fuel cells

    CERN Document Server

    Jiang, San Ping; Lu, Max

    2013-01-01

    There are a large number of books available on fuel cells; however, the majority are on specific types of fuel cells such as solid oxide fuel cells, proton exchange membrane fuel cells, or on specific technical aspects of fuel cells, e.g., the system or stack engineering. Thus, there is a need for a book focused on materials requirements in fuel cells. Key Materials in High-Temperature Fuel Cells is a concise source of the most important and key materials and catalysts in high-temperature fuel cells with emphasis on the most important solid oxide fuel cells. A related book will cover key mater

  15. High Temperature Protonic Conductors by Melt Growth

    Science.gov (United States)

    2007-11-02

    ceramic materials of BaCe1 -xNdxO3-a and Ba3(CaNb2)O9 that exhibit high temperature protonic conductance and superior mechanical properties at elevated...TEM). The mechanical behavior BaCe1 -xNdxO3-a (x=0 to 0.2) and Ba3(CaNb2)O9 ceramics in the elastic, brittle and plastic regime will be studied...spatial variations of compositions in BaCe1 -xNdxO3-a and Ba3(CaNb2)O9 following high temperature wet atmosphere treatment will be measured using a

  16. Dewetting-induced globule-coil transitions of model polymers and possible implications high-temperature and low-pressure unfolding of proteins.

    Science.gov (United States)

    Sumi, Tomonari; Imazaki, Nobuyuki; Sekino, Hideo

    2010-04-28

    A thermodynamic analysis of high-temperature and low-pressure unfolding of proteins using a coarse-grained multiscale simulation combined with a liquid-state density-functional theory is presented. In this study, a hydrophobic polymer chain is employed as a probe molecule for investigating qualitative changes in a hydration free energy surface acting on proteins with changes in temperature and pressure. When water is heated so that its vapor pressure is equal to the atmospheric pressure, it boils. Long-ranged dewetting or drying caused by a hydrophobic planar wall and a large hydrophobic solute surface is significantly enhanced as it approaches the liquid-vapor coexistence curve of water. In this study, we demonstrate that high-temperature and low-pressure unfolding of the polymer chain is interpreted as dewetting-induced unfolding that occurs as it approaches the liquid-vapor coexistence. The unfolding of proteins due to high-temperature and low-pressure denaturation enhances the long-ranged dewetting or drying around them. The long-ranged dewetting phenomenon is considered to be originating from positive changes in both volume and entropy due to the high-temperature and low-pressure denaturation of the proteins.

  17. One-dimensional modeling of radial heat removal during depressurized heatup transients in modular pebble-bed and prismatic high temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Savage, M.G.

    1984-07-01

    A one-dimensional computational model was developed to evaluate the heat removal capabilities of both prismatic-core and pebble-bed modular HTGRs during depressurized heatup transients. A correlation was incorporated to calculate the temperature- and neutron-fluence-dependent thermal conductivity of graphite. The modified Zehner-Schluender model was used to determine the effective thermal conductivity of a pebble bed, accounting for both conduction and radiation. Studies were performed for prismatic-core and pebble-bed modular HTGRs, and the results were compared to analyses performed by GA and GR, respectively. For the particular modular reactor design studied, the prismatic HTGR peak temperature was 2152.2/sup 0/C at 38 hours following the transient initiation, and the pebble-bed peak temperature was 1647.8/sup 0/C at 26 hours. These results compared favorably with those of GA and GE, with only slight differences caused by neglecting axial heat transfer in a one-dimensional radial model. This study found that the magnitude of the initial power density had a greater effect on the temperature excursion than did the initial temperature.

  18. Mathematical model for predicting transformation of high carbon steel during cooling and its application to on-line temperature control in hot strip mill; Kotansoko no hentai yosoku model no kaihatsu to sono jikki eno tekiyo

    Energy Technology Data Exchange (ETDEWEB)

    Suehiro, M.; Oda, T.; Senuma, T.; Konishi, S. [Nippon Steel Corp., Tokyo (Japan)

    1995-11-06

    A mathematical model for predicting transformation of high carbon steel during cooling (transformation from austenite to pearlite, ferrite, and bainite) has been developed. The basic equation for this model is the Cahn`s transformation progress behavior indicating equation, from which an equation was introduced that represents transformation velocity for the case of generation and growth of nuclei and for the case of site saturation. Using these equations makes it possible to calculate transformation in arbitrary cooling processes. In addition, a prediction model for hot processing transformation that expresses the influence of the hot processing on transformation was coupled with the transformation equation to improve the accuracy of transformation prediction. Rise in steel plate temperature that takes place because of generation of transformation latent heat during cooling was calculated by using a two-dimensional heat conduction equation. Off-line applications of this model include prediction of steel plate temperatures on a hot-run table, improvement in productivity by increasing plate passing speed in a continuous hot rolling process, and correction of variation in finishing rolling temperature. On-line applications include controls in hot-run water injection facilities, and automation of an on-line control system. 13 refs., 18 figs., 1 tab.

  19. High-temperature MAS-NMR at high spinning speeds.

    Science.gov (United States)

    Kirchhain, Holger; Holzinger, Julian; Mainka, Adrian; Spörhase, Andreas; Venkatachalam, Sabarinathan; Wixforth, Achim; van Wüllen, Leo

    2016-09-01

    A low cost version to enable high temperature MAS NMR experiments at temperatures of up to 700°C and spinning speeds of up to 10kHz is presented. The method relies on inductive heating using a metal coated rotor insert. The metal coating is accomplished via a two step process involving physical vapor deposition and galvanization.

  20. High Temperature Mechanisms for Venus Exploration

    Science.gov (United States)

    Ji, Jerri; Narine, Roop; Kumar, Nishant; Singh, Sase; Gorevan, Steven

    Future Venus missions, including New Frontiers Venus In-Situ Explorer and three Flagship Missions - Venus Geophysical Network, Venus Mobile Explorer and Venus Surface Sample Return all focus on searching for evidence of past climate change both on the surface and in the atmospheric composition as well as in the interior dynamics of the planet. In order to achieve these goals and objectives, many key technologies need to be developed for the Venus extreme environment. These key technologies include sample acquisition systems and other high-temperature mechanisms and mobility systems capable of extended operation when directly exposed to the Venus surface or lower atmosphere environment. Honeybee Robotics has developed two types of high temperature motors, the materials and components in both motors were selected based on the requirement to survive temperatures above a minimum of 460° C, at earth atmosphere. The prototype Switched Reluctance Motor (SRM) has been operated non-continuously for over 20 hours at Venus-like conditions (460° C temperature, mostly CO2 gas environment) and it remains functional. A drilling system, actuated by two SRMs was tested in Venus-like conditions, 460° C temperature and mostly CO2 gas environment, for more than 15 hours. The drill successfully completed three tests by drilling into chalk up to 6 inches deep in each test. A first generation Brushless DC (BLDC) Motor and high temperature resolver were also tested and the feasibility of the designs was demonstrated by the extended operation of both devices under Venus-like condition. Further development of the BLDC motor and resolver continues and these devices will, ultimately, be integrated into the development of a high temperature sample acquisition scoop and high temperature joint (awarded SBIR Phase II in October, 2007). Both the SR and BLDC motors will undergo extensive testing at Venus temperature and pressure (TRL6) and are expected to be mission ready before the next New

  1. High temperature reactors for cogeneration applications

    Energy Technology Data Exchange (ETDEWEB)

    Verfondern, Karl [Forschungszentrum Juelich (Germany). IEK-6; Allelein, Hans-Josef [Forschungszentrum Juelich (Germany). IEK-6; RWTH Aachen (Germany). Lehrstuhl fuer Reaktorsicherheit und -technik (LRST)

    2016-05-15

    There is a large potential for nuclear energy also in the non-electric heat market. Many industrial sectors have a high demand for process heat and steam at various levels of temperature and pressure to be provided for desalination of seawater, district heating, or chemical processes. The future generation of nuclear plants will be capable to enter the wide field of cogeneration of heat and power (CHP), to reduce waste heat and to increase efficiency. This requires an adjustment to multiple needs of the customers in terms of size and application. All Generation-IV concepts proposed are designed for coolant outlet temperatures above 500 C, which allow applications in the low and medium temperature range. A VHTR would even be able to cover the whole temperature range up to approx. 1 000 C.

  2. On-wafer high temperature characterization system

    Science.gov (United States)

    Teodorescu, L.; ǎghici, F., Dr; Rusu, I.; Brezeanu, G.

    2016-12-01

    In this work a on-wafer high temperature characterization system for wide bandgap semiconductor devices and circuits has been designed, implemented and tested. The proposed system can perform the wafer temperature adjustment in a large domain, from the room temperature up to 3000C with a resolution better than +/-0.50C. In order to obtain both low-noise measurements and low EMI, the heating element of the wafer chuck is supplied in two ways: one is from a DC linear power supply connected to the mains electricity, another one is from a second DC unit powered by batteries. An original temperature control algorithm, different from classical PID, is used to modify the power applied to the chuck.

  3. High-Temperature Shape Memory Polymers

    Science.gov (United States)

    Yoonessi, Mitra; Weiss, Robert A.

    2012-01-01

    physical conformation changes when exposed to an external stimulus, such as a change in temperature. Such materials have a permanent shape, but can be reshaped above a critical temperature and fixed into a temporary shape when cooled under stress to below the critical temperature. When reheated above the critical temperature (Tc, also sometimes called the triggering or switching temperature), the materials revert to the permanent shape. The current innovation involves a chemically treated (sulfonated, carboxylated, phosphonated, or other polar function group), high-temperature, semicrystalline thermoplastic poly(ether ether ketone) (Tg .140 C, Tm = 340 C) mix containing organometallic complexes (Zn++, Li+, or other metal, ammonium, or phosphonium salts), or high-temperature ionic liquids (e.g. hexafluorosilicate salt with 1-propyl-3- methyl imidazolium, Tm = 210 C) to form a network where dipolar or ionic interactions between the polymer and the low-molecular-weight or inorganic compound forms a complex that provides a physical crosslink. Hereafter, these compounds will be referred to as "additives". The polymer is semicrystalline, and the high-melt-point crystals provide a temporary crosslink that acts as a permanent crosslink just so long as the melting temperature is not exceeded. In this example case, the melting point is .340 C, and the shape memory critical temperature is between 150 and 250 C. PEEK is an engineering thermoplastic with a high Young fs modulus, nominally 3.6 GPa. An important aspect of the invention is the control of the PEEK functionalization (in this example, the sulfonation degree), and the thermal properties (i.e. melting point) of the additive, which determines the switching temperature. Because the compound is thermoplastic, it can be formed into the "permanent" shape by conventional plastics processing operations. In addition, the compound may be covalently cross - linked after forming the permanent shape by S-PEEK by applying ionizing

  4. High-Temperature Capacitor Polymer Films

    Science.gov (United States)

    Tan, Daniel; Zhang, Lili; Chen, Qin; Irwin, Patricia

    2014-12-01

    Film capacitor technology has been under development for over half a century to meet various applications such as direct-current link capacitors for transportation, converters/inverters for power electronics, controls for deep well drilling of oil and gas, direct energy weapons for military use, and high-frequency coupling circuitry. The biaxially oriented polypropylene film capacitor remains the state-of-the-art technology; however, it is not able to meet increasing demand for high-temperature (>125°C) applications. A number of dielectric materials capable of operating at high temperatures (>140°C) have attracted investigation, and their modifications are being pursued to achieve higher volumetric efficiency as well. This paper highlights the status of polymer dielectric film development and its feasibility for capacitor applications. High-temperature polymers such as polyetherimide (PEI), polyimide, and polyetheretherketone were the focus of our studies. PEI film was found to be the preferred choice for high-temperature film capacitor development due to its thermal stability, dielectric properties, and scalability.

  5. High temperature fatigue behaviour of intermetallics

    Indian Academy of Sciences (India)

    K Bhanu Sankara Rao

    2003-06-01

    There would be considerable benefits in developing new structural materials where high use temperatures and strength coupled with low density are minimum capabilities. Nickel and titanium aluminides exhibit considerable potential for near-term application in various branches of modern industry due to the number of property advantages they possess including low density, high melting temperature, high thermal conductivity, and excellent environmental resistance, and their amenability for significant improvment in creep and fatigue resistance through alloying. Reliability of intermetallics when used as engineering materials has not yet been fully established. Ductility and fracture toughness at room and intermediate temperatures continue to be lower than the desired values for production implementation. In this paper, progress made towards improving strain-controlled fatigue resistance of nickel and titanium aluminides is outlined. The effects of manufacturing processes and micro alloying on low cycle fatigue behaviour of NiAl are addressed. The effects of microstructure, temperature of testing, section thickness, brittle to ductile transition temperature, mean stress and environment on fatigue behaviour of same -TiAl alloys are discussed.

  6. Liquid Fuel Production from Biomass via High Temperature Steam Electrolysis

    Energy Technology Data Exchange (ETDEWEB)

    Grant L. Hawkes; Michael G. McKellar

    2009-11-01

    A process model of syngas production using high temperature electrolysis and biomass gasification is presented. Process heat from the biomass gasifier is used to heat steam for the hydrogen production via the high temperature steam electrolysis process. Hydrogen from electrolysis allows a high utilization of the biomass carbon for syngas production. Oxygen produced form the electrolysis process is used to control the oxidation rate in the oxygen-fed biomass gasifier. Based on the gasifier temperature, 94% to 95% of the carbon in the biomass becomes carbon monoxide in the syngas (carbon monoxide and hydrogen). Assuming the thermal efficiency of the power cycle for electricity generation is 50%, (as expected from GEN IV nuclear reactors), the syngas production efficiency ranges from 70% to 73% as the gasifier temperature decreases from 1900 K to 1500 K. Parametric studies of system pressure, biomass moisture content and low temperature alkaline electrolysis are also presented.

  7. Incorporating the Johnson-Cook Constitutive Model and a Soft Computational Approach for Predicting the High-Temperature Flow Behavior of Sn-5Sb Solder Alloy: A Comparative Study for Processing Map Development

    Science.gov (United States)

    Vafaeenezhad, H.; Seyedein, S. H.; Aboutalebi, M. R.; Eivani, A. R.

    2016-09-01

    The high-temperature flow behavior of Sn-5Sb lead-free solder alloy has been investigated using isothermal hot compression experiments at 298 K to 400 K and strain rate between 0.0005 s-1 and 0.01 s-1. The flow stress under these test conditions was modeled using constitutive equations based on the Johnson-Cook (J-C) model and an artificial neural network (ANN). Three input factors, i.e., temperature, strain rate, and true strain, were incorporated into the network, and the flow stress was considered as the system output. One hidden layer was adopted in the simulations. Furthermore, a comparative study was carried out on the potential of the two proposed models to characterize the high-temperature flow behavior of this alloy. The capability of the models was assessed by comparing the simulation predictions using a correlation coefficient (R 2). The stresses predicted by both models presented good agreement with experimental results. In addition, it was found that the ANN model could predict the high-temperature deformation more precisely over the whole temperature and strain rate ranges. However, this is strongly dependent on the availability of extensive, high-quality data and characteristic variables.

  8. Incorporating the Johnson-Cook Constitutive Model and a Soft Computational Approach for Predicting the High-Temperature Flow Behavior of Sn-5Sb Solder Alloy: A Comparative Study for Processing Map Development

    Science.gov (United States)

    Vafaeenezhad, H.; Seyedein, S. H.; Aboutalebi, M. R.; Eivani, A. R.

    2017-01-01

    The high-temperature flow behavior of Sn-5Sb lead-free solder alloy has been investigated using isothermal hot compression experiments at 298 K to 400 K and strain rate between 0.0005 s-1 and 0.01 s-1. The flow stress under these test conditions was modeled using constitutive equations based on the Johnson-Cook (J-C) model and an artificial neural network (ANN). Three input factors, i.e., temperature, strain rate, and true strain, were incorporated into the network, and the flow stress was considered as the system output. One hidden layer was adopted in the simulations. Furthermore, a comparative study was carried out on the potential of the two proposed models to characterize the high-temperature flow behavior of this alloy. The capability of the models was assessed by comparing the simulation predictions using a correlation coefficient ( R 2). The stresses predicted by both models presented good agreement with experimental results. In addition, it was found that the ANN model could predict the high-temperature deformation more precisely over the whole temperature and strain rate ranges. However, this is strongly dependent on the availability of extensive, high-quality data and characteristic variables.

  9. High strain rate behavior of pure metals at elevated temperature

    Science.gov (United States)

    Testa, Gabriel; Bonora, Nicola; Ruggiero, Andrew; Iannitti, Gianluca; Domenico, Gentile

    2013-06-01

    In many applications and technology processes, such as stamping, forging, hot working etc., metals and alloys are subjected to elevated temperature and high strain rate deformation process. Characterization tests, such as quasistatic and dynamic tension or compression test, and validation tests, such as Taylor impact and DTE - dynamic tensile extrusion -, provide the experimental base of data for constitutive model validation and material parameters identification. Testing material at high strain rate and temperature requires dedicated equipment. In this work, both tensile Hopkinson bar and light gas gun where modified in order to allow material testing under sample controlled temperature conditions. Dynamic tension tests and Taylor impact tests, at different temperatures, on high purity copper (99.98%), tungsten (99.95%) and 316L stainless steel were performed. The accuracy of several constitutive models (Johnson and Cook, Zerilli-Armstrong, etc.) in predicting the observed material response was verified by means of extensive finite element analysis (FEA).

  10. Temperature influences in receiver clock modelling

    Science.gov (United States)

    Wang, Kan; Meindl, Michael; Rothacher, Markus; Schoenemann, Erik; Enderle, Werner

    2016-04-01

    In Precise Point Positioning (PPP), hardware delays at the receiver site (receiver, cables, antenna, …) are always difficult to be separated from the estimated receiver clock parameters. As a result, they are partially or fully contained in the estimated "apparent" clocks and will influence the deterministic and stochastic modelling of the receiver clock behaviour. In this contribution, using three years of data, the receiver clock corrections of a set of high-precision Hydrogen Masers (H-Masers) connected to stations of the ESA/ESOC network and the International GNSS Service (IGS) are firstly characterized concerning clock offsets, drifts, modified Allan deviations and stochastic parameters. In a second step, the apparent behaviour of the clocks is modelled with the help of a low-order polynomial and a known temperature coefficient (Weinbach, 2013). The correlations between the temperature and the hardware delays generated by different types of antennae are then analysed looking at daily, 3-day and weekly time intervals. The outcome of these analyses is crucial, if we intend to model the receiver clocks in the ground station network to improve the estimation of station-related parameters like coordinates, troposphere zenith delays and ambiguities. References: Weinbach, U. (2013) Feasibility and impact of receiver clock modeling in precise GPS data analysis. Dissertation, Leibniz Universität Hannover, Germany.

  11. High Accuracy, Miniature Pressure Sensor for Very High Temperatures Project

    Data.gov (United States)

    National Aeronautics and Space Administration — SiWave proposes to develop a compact, low-cost MEMS-based pressure sensor for very high temperatures and low pressures in hypersonic wind tunnels. Most currently...

  12. High Temperature Polymer Electrolyte Fuel Cells

    DEFF Research Database (Denmark)

    Fleige, Michael

    This thesis presents the development and application of electrochemical half-cell setups to study the catalytic reactions taking place in High Temperature Polymer Electrolyte Fuel Cells (HTPEM-FCs): (i) a pressurized electrochemical cell with integrated magnetically coupled rotating disk electrode...... of dissolved oxygen. A potential step method (hydrodynamic chronocoulometry) is evaluated for simultaneous measurement of diffusivity and solubility of oxygen by means of RDE. Finally, the ORR tests are extended to conc. H3PO4 at more relevant working temperatures and under increased oxygen pressure. Direct...... of platinumphosphoric acid. At room temperature, a relative slow ORR hindering process is active, which requires using a fast method (cyclic voltammetry with high scan rate / hydrodynamic chronocoulometry) to accurately measure the diffusion limited currents, and thus, oxygen diffusivity and solubility. In conc. H3PO4...

  13. Gravimeter using high-temperature superconductor bearing.

    Energy Technology Data Exchange (ETDEWEB)

    Hull, J. R.

    1998-09-11

    We have developed a sensitive gravimeter concept that uses an extremely low-friction bearing based on a permanent magnet (PM) levitated over a high-temperature superconductor (HTS). A mass is attached to the PM by means of a cantilevered beam, and the combination of PM and HTS forms a bearing platform that has low resistance to rotational motion but high resistance to horizontal, vertical, or tilting motion. The combination acts as a low-loss torsional pendulum that can be operated in any orientation. Gravity acts on the cantilevered beam and attached mass, accelerating them. Variations in gravity can be detected by time-of-flight acceleration, or by a control coil or electrode that would keep the mass stationary. Calculations suggest that the HTS gravimeter would be as sensitive as present-day superconducting gravimeters that need cooling to liquid helium temperatures, but the HTS gravimeter needs cooling only to liquid nitrogen temperatures.

  14. INVESTIGATION OF SURFACE TEMPERATURE IN HIGH-EFFICIENCY DEEP GRINDING

    Institute of Scientific and Technical Information of China (English)

    Zhao Henghua; Cai Guangqi; Jin Tan

    2005-01-01

    A new thermal model with triangular heat flux distribution is given in high-efficiency deep grinding. The mathematical expressions are driven to calculate the surface temperature. The transient behavior of the maximum temperature on contact area is investigated in different grinding conditions with a J-type thermocouple. The maximum contact temperatures measured in different conditions are found to be between 1 000 ℃ and 1 500 ℃ in burn-out conditions. The experiment results show good agreement with the new thermal model.

  15. Computational Thermodynamic Modeling of Hot Corrosion of Alloys Haynes 242 and HastelloyTM N for Molten Salt Service in Advanced High Temperature Reactors

    Energy Technology Data Exchange (ETDEWEB)

    V. Glazoff, Michael; Charit, Indrajt; Sabharwall, Piyush

    2014-09-17

    An evaluation of thermodynamic aspects of hot corrosion of the superalloys Haynes 242 and HastelloyTM N in the eutectic mixtures of KF and ZrF4 is carried out for development of Advanced High Temperature Reactor (AHTR). This work models the behavior of several superalloys, potential candidates for the AHTR, using computational thermodynamics tool (ThermoCalc), leading to the development of thermodynamic description of the molten salt eutectic mixtures, and on that basis, mechanistic prediction of hot corrosion. The results from these studies indicated that the principal mechanism of hot corrosion was associated with chromium leaching for all of the superalloys described above. However, HastelloyTM N displayed the best hot corrosion performance. This was not surprising given it was developed originally to withstand the harsh conditions of molten salt environment. However, the results obtained in this study provided confidence in the employed methods of computational thermodynamics and could be further used for future alloy design efforts. Finally, several potential solutions to mitigate hot corrosion were proposed for further exploration, including coating development and controlled scaling of intermediate compounds in the KF-ZrF4 system.

  16. Nuclear and Quark Matter at High Temperature

    CERN Document Server

    Biro, T S; Schram, Z

    2016-01-01

    We review important ideas on nuclear and quark matter description on the basis of high- temperature field theory concepts, like resummation, dimensional reduction, interaction scale separation and spectral function modification in media. Statistical and thermodynamical concepts are spotted in the light of these methods concentrating on the - partially still open - problems of the hadronization process.

  17. Technology of high temperature organic coolant

    Energy Technology Data Exchange (ETDEWEB)

    Makin, R.S.; Vorobei, M.P.; Kuprienko, V.A.; Starkov, V.A.; Tsykanov, V.A.; Checketkin, Y.V. [Research Institute of Atomic Reactors, Ulyanovsk (Russian Federation)

    1993-12-31

    Research has been performed on the problems related to the use of high temperature organic coolants in small and medium nuclear power plants. The work performed and also the experience of operating the ARBUS reactor confirmed the inherent safety features, reliability, and enhanced safety margins of the plants with this type of coolants. The advantages of this system and research highlights are presented.

  18. Enamel for high-temperature superalloys

    Science.gov (United States)

    Levin, H.; Lent, W. E.

    1977-01-01

    Desired optical and high temperature enamel properties are obtained with glasses prepared from the system Li2O-ZrO2-nSiO2. Molar compositions range from n=4 to n=1.3, to which are added minor amounts in varying combinations of alumina, alkali fluorides, boric oxide, alkali oxides, and akaline earth oxides.

  19. Nuclear and quark matter at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Biro, Tamas S. [H.A.S. Wigner Research Centre for Physics, Budapest (Hungary); Jakovac, Antal [Roland Eotvos University, Budapest (Hungary); Schram, Zsolt [University of Debrecen, Institute for Theoretical Physics, Debrecen (Hungary)

    2017-03-15

    We review important ideas on nuclear and quark matter description on the basis of high-temperature field theory concepts, like resummation, dimensional reduction, interaction scale separation and spectral function modification in media. Statistical and thermodynamical concepts are spotted in the light of these methods concentrating on the -partially still open- problems of the hadronization process. (orig.)

  20. Analysis of iron oxidation at high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Slattery, J.C.; Peng, K.Y.; Gadalla, A.M.; Gadalla, N. [Texas A and M Univ., College Station, TX (United States). Dept. of Chemical Engineering

    1995-10-01

    A new theory for the high-temperature oxidation of iron is proposed, in which the rate-limiting step is ternary diffusion of ferric, ferrous, and oxygen ions in the iron oxides that are formed. The predictions of this theory are compared with previously published experimental data. The only thermodynamic information required is a phase diagram.

  1. Dynamics of Gauge Fields at High Temperature

    NARCIS (Netherlands)

    Nauta, B.J.

    2000-01-01

    An effective description of dynamical Bose fields is provided by the classical (high-temperature) limit of thermal field theory. The main subject of this thesis is to improve the ensuing classical field theory, that is, to include the dominant quantum corrections and to add counter terms for the Ray

  2. Photoemission studies of high-temperature superconductivity

    Energy Technology Data Exchange (ETDEWEB)

    Margaritondo, G. (Inst. de Physique Appliquee, Ecole Polytechnique Federale de Lausanne, CH-1015 Lausanne (CH))

    1990-11-01

    Photoemission spectroscopy has recently emerged as one of the leading techniques in the study of high-temperature superconductors. Relevant successes include the direct detection of the superconductivity gap, tests for departure from Fermi-liquid behavior, and many interface chemical studies with technological interest. The authors present a review of the fundamental and applied aspects of this technique.

  3. High-temperature carbidization of carboniferous rocks

    Science.gov (United States)

    Goldin, B. A.; Grass, V. E.; Nadutkin, A. V.; Nazarova, L. Yu.

    2009-08-01

    Processes of thermal metamorphism of carboniferous rocks have been studied experimentally. The conditions of high-temperature interaction of shungite carbon with components of the contained rocks, leading to formation of carbide compounds, have been determined. The results of this investigation contribute to the works on searching for new raw material for prospective material production.

  4. 10.3 High-temperature Instrumentation

    Science.gov (United States)

    Piazza, Anthony

    2008-01-01

    This viewgraph presentation describes high temperature instrumentation development from 1960-1970, 1980-1990 and 2000-present. The contents include: 1) Background; 2) Objective; 3) Application and Sensor; 4) Attachment Techniques; 5) Evaluation/Characterization Testing; and 6) Future testing.

  5. High-temperature langasite SAW oxygen sensor.

    Science.gov (United States)

    Zheng, Peng; Chin, Tao-Lun; Greve, David; Oppenheim, Irving; Malone, Vanessa; Cao, Limin

    2011-08-01

    High-temperature langasite SAW oxygen sensors using sputtered ZnO as a resistive gas-sensing layer were fabricated and tested. Sensitivity to oxygen gas was observed between 500°C to 700°C, with a sensitivity peak at about 625°C, consistent with the theoretical predictions of the acoustoelectric effect.

  6. Dynamics of Gauge Fields at High Temperature

    NARCIS (Netherlands)

    Nauta, B.J.

    2000-01-01

    An effective description of dynamical Bose fields is provided by the classical (high-temperature) limit of thermal field theory. The main subject of this thesis is to improve the ensuing classical field theory, that is, to include the dominant quantum corrections and to add counter terms for the Ray

  7. Solar-driven high temperature radiant cooling

    Institute of Scientific and Technical Information of China (English)

    SONG ZhaoPei; WANG RuZhu; ZHAI XiaoQiang

    2009-01-01

    Solar energy is widely used as one of the most important renewable energy. In addition to the growing applications of solar PV and solar water heater, solar cooling is also considered very valuable and the related researches are developing fast because of the synchronism between solar irradiance and building cooling load. Current studies mainly focus on the high temperature solar collector technique and heat-driven cooling technique, while little concern has been paid to the transport process of cooling power. In this paper, the high temperature radiant cooling is studied as an alternative way for transporting cooling power, and the performance of the combination of radiant ceiling and solar cooling is also studied. From simulation and theoretical analysis results, high temperature radiant cooling terminal shows better cooling power transportation ability against conventional air-conditioning terminal, and its thermal comfort is improved. Experiment results indicate that radiant cooling can enhance the chiller's COP (Coefficient of Performance) by 17% and cooling power regeneration by 50%.According to analysis in this paper, high temperature radiant cooling is proved to be suitable for solar cooling system, and out work can serve as a reference for later system design and promotion.

  8. High Temperature Corrosion in Biomass Incineration Plants

    DEFF Research Database (Denmark)

    Montgomery, Melanie; Maahn, Ernst emanuel; Gotthjælp, K.

    1997-01-01

    The aim of the project is to study the role of ash deposits in high temperature corrosion of superheater materials in biomass and refuse fire combined heat and power plants. The project has included the two main activities: a) A chemical characterisation of ash deposits collected from a major...

  9. The Evolution of High Temperature Gas Sensors.

    Energy Technology Data Exchange (ETDEWEB)

    Garzon, F. H. (Fernando H.); Brosha, E. L. (Eric L.); Mukundan, R. (Rangachary)

    2001-01-01

    Gas sensor technology based on high temperature solid electrolytes is maturing rapidly. Recent advances in metal oxide catalysis and thin film materials science has enabled the design of new electrochemical sensors. We have demonstrated prototype amperometric oxygen sensors, nernstian potentiometric oxygen sensors that operate in high sulfur environments, and hydrocarbon and carbon monoxide sensing mixed potentials sensors. Many of these devices exhibit part per million sensitivities, response times on the order of seconds and excellent long-term stability.

  10. Temperature dependent extension of a hysteresis model

    OpenAIRE

    Sixdenier, Fabien; MESSAL, Oualid; Hilal, Alaa; Martin, Christian; Raulet, Marie-Ange

    2015-01-01

    International audience; Some soft magnetic materials (like ferrites but not only) are strongly dependent of the temperature. In order to predict their behaviour in electrical devices, engineers need hysteresis models able to take into account the temperature. This paper is an attempt to take into account the temperature in an existing model of hysteresis through its parameters. Variations of some parameters are issued from Weiss’s works and others have to be fitted numerically. Simulation res...

  11. High-pressure-high-temperature treatment of natural diamonds

    CERN Document Server

    Royen, J V

    2002-01-01

    The results are reported of high-pressure-high-temperature (HPHT) treatment experiments on natural diamonds of different origins and with different impurity contents. The diamonds are annealed in a temperature range up to 2000 sup o C at stabilizing pressures up to 7 GPa. The evolution is studied of different defects in the diamond crystal lattice. The influence of substitutional nitrogen atoms, plastic deformation and the combination of these is discussed. Diamonds are characterized at room and liquid nitrogen temperature using UV-visible spectrophotometry, Fourier transform infrared spectrophotometry and photoluminescence spectrometry. The economic implications of diamond HPHT treatments are discussed.

  12. Projections of high resolution climate changes for South Korea using multiple-regional climate models based on four RCP scenarios. Part 1: surface air temperature

    Science.gov (United States)

    Suh, Myoung-Seok; Oh, Seok-Geun; Lee, Young-Suk; Ahn, Joong-Bae; Cha, Dong-Hyun; Lee, Dong-Kyou; Hong, Song-You; Min, Seung-Ki; Park, Seong-Chan; Kang, Hyun-Suk

    2016-05-01

    We projected surface air temperature changes over South Korea during the mid (2026-2050) and late (2076-2100) 21st century against the current climate (1981-2005) using the simulation results from five regional climate models (RCMs) driven by Hadley Centre Global Environmental Model, version 2, coupled with the Atmosphere- Ocean (HadGEM2-AO), and two ensemble methods (equal weighted averaging, weighted averaging based on Taylor's skill score) under four Representative Concentration Pathways (RCP) scenarios. In general, the five RCM ensembles captured the spatial and seasonal variations, and probability distribution of temperature over South Korea reasonably compared to observation. They particularly showed a good performance in simulating annual temperature range compared to HadGEM2-AO. In future simulation, the temperature over South Korea will increase significantly for all scenarios and seasons. Stronger warming trends are projected in the late 21st century than in the mid-21st century, in particular under RCP8.5. The five RCM ensembles projected that temperature changes for the mid/late 21st century relative to the current climate are +1.54°C/+1.92°C for RCP2.6, +1.68°C/+2.91°C for RCP4.5, +1.17°C/+3.11°C for RCP6.0, and +1.75°C/+4.73°C for RCP8.5. Compared to the temperature projection of HadGEM2-AO, the five RCM ensembles projected smaller increases in temperature for all RCP scenarios and seasons. The inter-RCM spread is proportional to the simulation period (i.e., larger in the late-21st than mid-21st century) and significantly greater (about four times) in winter than summer for all RCP scenarios. Therefore, the modeled predictions of temperature increases during the late 21st century, particularly for winter temperatures, should be used with caution.

  13. Analysis of frozen startup of high-temperature heat pipes and three-dimensional modeling of block-heated heat pipes

    Science.gov (United States)

    Faghri, Amir

    1991-11-01

    The use of high-temperature heat pipes has been proposed for cooling the leading edges and nose cones of re-entry vehicles, rail guns, and laser mirrors, as well as for the thermal management of future hypersonic vehicle structures. The startup behavior of high temperature heat pipes from the frozen state was investigated both numerically and experimentally for various heat loads and input locations. A high temperature sodium/stainless steel heat pipe with multiple heat sources and sinks was fabricated, processed, and tested. A numerical simulation of the transient heat pipe performance including the vapor region, wick structure, and the heat pipe wall is given. Furthermore, experimental and numerical analyses of several operating parameters of a low-temperature copper-water heat pipe under uniform circumferential heating and block heating has been performed. Finally, a numerical analysis of transient heat pipe performance including nonconventional heat pipes with nonuniform heat distributions is presented. Numerical calculations were then made for a leading edge heat pipe with localized high heat fluxes.

  14. Well cement aging in various H{sub 2}S-CO{sub 2} fluids at high pressure and high temperature : experiments and modeling

    Energy Technology Data Exchange (ETDEWEB)

    Jacquemet, N.; Pironon, J. [Nancy Univ. (France). CNRS-CREGU; BRGM, Orleans (France); Lagneau, V. [Mines Paris (France); Saint-Marc, J. [Total (France)

    2010-07-01

    The mitigation of residual gases from oil and gas wells was discussed with particular reference to the oil and gas industry's efforts to develop gas and oil reservoirs with high non-hydrocarbon content; reduce gas releases to the atmosphere; avoid expensive gas mineralization and storage; and re-inject gases into deep saline aquifers or depleted reservoir for enhanced oil recovery. The chemical reactions that occur between the well cement and the gas or brine within an acid gas geological storage site may alter the hydraulic properties of the material in terms of porosity, diffusivity and permeability. As a consequence, its mechanical strength may be affected. The well's sheath may provide a pathway for the hydrogen sulphide (H{sub 2}S) and carbon dioxide (CO{sub 2}) fluids to reach the surface. This study involved batch experiments at 500 bar and 120 degrees C to investigate the reactivity of a deep well cement analogue in contact with a brine with dissolved H{sub 2}S-CO{sub 2}; a dry H{sub 2}S-CO{sub 2} supercritical phase; and a two-phase fluid associating a brine with dissolved H{sub 2}S-CO{sub 2} and a H{sub 2}S-CO{sub 2} supercritical phase. The cement was carbonated by the CO{sub 2}. Different mineralogical alteration profiles were observed based on the various exposures. The study showed that H{sub 2}S reacts with the minor iron-bearing minerals of cement to form sulphate/sulphide mixtures. The maximum cement carbonation occurred within the dry supercritical phase without liquid water. The porosity decreased in all experiments from about 40 to 15 percent. A calcium carbonate coating precipitated on the surface cement because of the low W/R ratio in the reactor. This prevented further reactions when the cement was immersed in brine. tabs., figs.

  15. Modeling of High-Strain-Rate Deformation, Fracture, and Impact Behavior of Advanced Gas Turbine Engine Materials at Low and Elevated Temperatures

    Science.gov (United States)

    Shazly, Mostafa; Nathenson, David; Prakash, Vikas

    2003-01-01

    Gamma titanium aluminides have received considerable attention over the last decade. These alloys are known to have low density, good high temperature strength retention, and good oxidation and corrosion resistance. However, poor ductility and low fracture toughness have been the key limiting factors in the full utilization of these alloys. More recently, Gamma-met PX has been developed by GKSS, Germany. These alloys have been observed to have superior strengths at elevated temperatures and quasi-static deformation rates and good oxidation resistance at elevated temperatures when compared with other gamma titanium aluminides. The present paper discusses results of a study to understand dynamic response of gamma-met PX in uniaxial compression. The experiments were conducted by using a modified split Hopkinson pressure bar between room temperature and 900 C and strain rates of up to 3500 per second. The Gamma met PX alloy showed superior strength when compared to nickel based superalloys and other gamma titanium aluminides at all test temperatures. It also showed strain and strain-rate hardening at all levels of strain rates and temperatures and without yield anomaly up to 900 C. After approximately 600 C, thermal softening is observed at all strain rates with the rate of thermal softening increasing dramatically between 800 and 900 C. However, these flow stress levels are comparatively higher in Gamma met PX than those observed for other TiAl alloys.

  16. Comments on theories of high temperature superconductivity

    Directory of Open Access Journals (Sweden)

    T. M. Rice

    2006-09-01

    Full Text Available   The recently discovered MgB2 superconductors have a record transition temperature for a BCS superconductor due to the high vibration frequencies associated with its light elements. The transition temperatures in the cuprate family of superconductors are much higher but these do not fit the BCS paradigm. The most promising microscopic origin for their many anomalous properties lies in magnetic pairing described by the RVB (Resonant Valence Bond ansatz. However a comprehensive theoretical description of the key anomalous properties of the cuprates remains to be an open challenge.

  17. Size effect of sandstone after high temperature under uniaxial compression

    Institute of Scientific and Technical Information of China (English)

    SU Hai-jian; JING Hong-wen; MAO Xian-biao; ZHAO Hong-hui; YIN Qian; WANG Chen

    2015-01-01

    Uniaxial compression tests on sandstone samples with five different sizes after high temperature processes were performed in order to investigate the size effect and its evolution. The test results show that the density, longitudinal wave velocity, peak strength, average modulus and secant modulus of sandstone decrease with the increase of temperature, however, peak strain increases gradually. With the increase of ratio of height to diameter, peak strength of sandstone decreases, which has an obvious size effect. A new theoretical model of size effect of sandstone material considering the influence of temperature is put forward, and with the increase of temperature, the size effect is more apparent. The threshold decreases gradually with the increase of temperature, and the deviations of the experimental values and the theoretical values are between 0.44% and 6.06%, which shows quite a credibility of the theoretical model.

  18. The metallurgy of high temperature alloys

    Science.gov (United States)

    Tien, J. K.; Purushothaman, S.

    1976-01-01

    Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

  19. Optically transparent high temperature shape memory polymers.

    Science.gov (United States)

    Xiao, Xinli; Qiu, Xueying; Kong, Deyan; Zhang, Wenbo; Liu, Yanju; Leng, Jinsong

    2016-03-21

    Optically transparent shape memory polymers (SMPs) have potential in advanced optoelectronic and other common shape memory applications, and here optically transparent shape memory polyimide is reported for the first time. The polyimide possesses a glass transition temperature (Tg) of 171 °C, higher than the Tg of other transparent SMPs reported, and the influence of molecular structure on Tg is discussed. The 120 μm thick polyimide film exhibits transmittance higher than 81% in 450-800 nm, and the possible mechanism of its high transparency is analyzed, which will benefit further research on other transparent high temperature SMPs. The transparent polyimide showed excellent thermomechanical properties and shape memory performances, and retained high optical transparency after many shape memory cycles.

  20. INTERPARTICLE FORCES IN HIGH TEMPERATURE FLUIDIZATION OF GELDART A PARTICLES

    Institute of Scientific and Technical Information of China (English)

    Heping Cui; Jamal Chaouki

    2004-01-01

    Previous reports and current studies show that fluidization of some Geldart A particles is enhanced by increasing bed temperature. Both the averaged local particle concentration and the particle concentration in the dense phase decrease with increasing bed temperature, at constant superficial gas velocities. However, conventional models fail to predict these changes, because the role of interparticle forces is usually neglected at different bed temperatures.Here, the interparticle forces are analyzed to explore the mechanism of gas-solid fluidization at high temperatures. Indeed, as the temperature increases, the interparticle attractive forces decrease while the interparticle repulsive forces increase. Consequently, fluidization behaviors of some Geldart A particles seem to increasingly shift from typical Geldart A towards B with increasing temperature.

  1. High temperature sensors for exhaust diagnosis

    Energy Technology Data Exchange (ETDEWEB)

    Svenningstorp, Henrik

    2000-07-01

    One of the largest problems that we will have to deal with on this planet this millennium is to stop the pollution of our environment. In many of the ongoing works to reduce toxic emissions, gas sensors capable of enduring rough environments and high temperatures, would be a great tool. The different applications where sensors like this would be useful vary between everything from online measurement in the paper industry and food industry to measurement in the exhaust pipe of a car. In my project we have tested Schottky diodes and MlSiCFET sensor as gas sensors operating at high temperatures. The measurement condition in the exhaust pipe of a car is extremely tough, not only is the temperature high and the different gases quite harmful, there are also a lot of particles that can affect the sensors in an undesirable way. In my project we have been testing Schottky diodes and MlSiCFET sensors based on SiC as high temperature sensors, both in the laboratory with simulated exhaust and after a real engine. In this thesis we conclude that these sensors can work in the hostile environment of an engines exhaust. It is shown that when measuring in a gas mixture with a fixed I below one, where the I-value is controlled by the O{sub 2} concentration, a sensor with a catalytic gate metal as sensitive material respond more to the increased O{sub 2} concentration than the increased HC concentration when varying the two correspondingly. A number of different sensors have been tested in simulated exhaust towards NO{sub x}. It was shown that resistivity changes in the thin gate metal influenced the gas response. Tests have been performed where sensors were a part of a SCR system with promising results concerning NH{sub 3} sensitivity. With a working temperature of 300 deg C there is no contamination of the metal surface.

  2. High Temperature Fluoride Salt Test Loop

    Energy Technology Data Exchange (ETDEWEB)

    Aaron, Adam M. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Cunningham, Richard Burns [Univ. of Tennessee, Knoxville, TN (United States); Fugate, David L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Holcomb, David Eugene [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Kisner, Roger A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Peretz, Fred J. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Robb, Kevin R. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Wilson, Dane F. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Yoder, Jr, Graydon L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2015-12-01

    Effective high-temperature thermal energy exchange and delivery at temperatures over 600°C has the potential of significant impact by reducing both the capital and operating cost of energy conversion and transport systems. It is one of the key technologies necessary for efficient hydrogen production and could potentially enhance efficiencies of high-temperature solar systems. Today, there are no standard commercially available high-performance heat transfer fluids above 600°C. High pressures associated with water and gaseous coolants (such as helium) at elevated temperatures impose limiting design conditions for the materials in most energy systems. Liquid salts offer high-temperature capabilities at low vapor pressures, good heat transport properties, and reasonable costs and are therefore leading candidate fluids for next-generation energy production. Liquid-fluoride-salt-cooled, graphite-moderated reactors, referred to as Fluoride Salt Reactors (FHRs), are specifically designed to exploit the excellent heat transfer properties of liquid fluoride salts while maximizing their thermal efficiency and minimizing cost. The FHR s outstanding heat transfer properties, combined with its fully passive safety, make this reactor the most technologically desirable nuclear power reactor class for next-generation energy production. Multiple FHR designs are presently being considered. These range from the Pebble Bed Advanced High Temperature Reactor (PB-AHTR) [1] design originally developed by UC-Berkeley to the Small Advanced High-Temperature Reactor (SmAHTR) and the large scale FHR both being developed at ORNL [2]. The value of high-temperature, molten-salt-cooled reactors is also recognized internationally, and Czechoslovakia, France, India, and China all have salt-cooled reactor development under way. The liquid salt experiment presently being developed uses the PB-AHTR as its focus. One core design of the PB-AHTR features multiple 20 cm diameter, 3.2 m long fuel channels

  3. Thermoelectric properties by high temperature annealing

    Science.gov (United States)

    Ren, Zhifeng (Inventor); Chen, Gang (Inventor); Kumar, Shankar (Inventor); Lee, Hohyun (Inventor)

    2009-01-01

    The present invention generally provides methods of improving thermoelectric properties of alloys by subjecting them to one or more high temperature annealing steps, performed at temperatures at which the alloys exhibit a mixed solid/liquid phase, followed by cooling steps. For example, in one aspect, such a method of the invention can include subjecting an alloy sample to a temperature that is sufficiently elevated to cause partial melting of at least some of the grains. The sample can then be cooled so as to solidify the melted grain portions such that each solidified grain portion exhibits an average chemical composition, characterized by a relative concentration of elements forming the alloy, that is different than that of the remainder of the grain.

  4. High Temperature Polymer Electrolyte Fuel Cells

    DEFF Research Database (Denmark)

    Fleige, Michael

    This thesis presents the development and application of electrochemical half-cell setups to study the catalytic reactions taking place in High Temperature Polymer Electrolyte Fuel Cells (HTPEM-FCs): (i) a pressurized electrochemical cell with integrated magnetically coupled rotating disk electrode...... (RDE) and (ii) a gas diffusion electrode (GDE) setup designed for experiments in conc. H3PO4. The pressurized cell is demonstrated by tests on polycrystalline platinum electrodes up to 150 ºC. Functionality of the RDE system is proved studying the oxygen reduction reaction (ORR) at temperatures up...... to 140 ºC and oxygen pressures up to ~100 bar at room temperature. The GDE cell is successfully tested at 130 ºC by means of direct oxidation of methanol and ethanol, respectively. In the second part of the thesis, the emphasis is put on the ORR in H3PO4 with particular focus on the mass transport...

  5. Quench in high temperature superconductor magnets

    CERN Document Server

    Schwartz, J

    2013-01-01

    High field superconducting magnets using high temperature superconductors are being developed for high energy physics, nuclear magnetic resonance and energy storage applications. Although the conductor technology has progressed to the point where such large magnets can be readily envisioned, quench protection remains a key challenge. It is well-established that quench propagation in HTS magnets is very slow and this brings new challenges that must be addressed. In this paper, these challenges are discussed and potential solutions, driven by new technologies such as optical fiber based sensors and thermally conducting electrical insulators, are reviewed.

  6. Gasification of high ash, high ash fusion temperature bituminous coals

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Guohai; Vimalchand, Pannalal; Peng, WanWang

    2015-11-13

    This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150.degree. C. to 1500.degree. C. range as well as in excess of 1500.degree. C. In a preferred embodiment, such coals are dealt with a two stage gasification process--a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

  7. Gasification of high ash, high ash fusion temperature bituminous coals

    Science.gov (United States)

    Liu, Guohai; Vimalchand, Pannalal; Peng, WanWang

    2015-11-13

    This invention relates to gasification of high ash bituminous coals that have high ash fusion temperatures. The ash content can be in 15 to 45 weight percent range and ash fusion temperatures can be in 1150.degree. C. to 1500.degree. C. range as well as in excess of 1500.degree. C. In a preferred embodiment, such coals are dealt with a two stage gasification process--a relatively low temperature primary gasification step in a circulating fluidized bed transport gasifier followed by a high temperature partial oxidation step of residual char carbon and small quantities of tar. The system to process such coals further includes an internally circulating fluidized bed to effectively cool the high temperature syngas with the aid of an inert media and without the syngas contacting the heat transfer surfaces. A cyclone downstream of the syngas cooler, operating at relatively low temperatures, effectively reduces loading to a dust filtration unit. Nearly dust- and tar-free syngas for chemicals production or power generation and with over 90%, and preferably over about 98%, overall carbon conversion can be achieved with the preferred process, apparatus and methods outlined in this invention.

  8. Energy storage via high temperature superconductivity (SMES)

    Energy Technology Data Exchange (ETDEWEB)

    Mikkonen, R. [Tampere Univ. of Technology (Finland)

    1998-10-01

    The technology concerning high temperature superconductors (HTS) is matured to enabling different kind of prototype applications including SMES. Nowadays when speaking about HTS systems, attention is focused on the operating temperature of 20-30 K, where the critical current and flux density are fairly close to 4.2 K values. In addition by defining the ratio of the energy content of a novel HTS magnetic system and the required power to keep the system at the desired temperature, the optimum settles to the above mentioned temperature range. In the frame of these viewpoints a 5 kJ HTS SMES system has been designed and tested at Tampere University of Technology with a coil manufactured by American Superconductor (AMSC). The HTS magnet has inside and outside diameters of 252 mm and 317 mm, respectively and axial length of 66 mm. It operates at 160 A and carries a total of 160 kA-turns to store the required amount of energy. The effective magnetic inductance is 0.4 H and the peak axial field is 1.7 T. The magnet is cooled to the operating temperature of 20 K with a two stage Gifford-McMahon type cryocooler with a cooling power of 60 W at 77 K and 8 W at 20 K. The magnetic system has been demonstrated to compensate a short term loss of power of a sensitive consumer

  9. High temperature deformation of silicon steel

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Calvillo, Pablo, E-mail: pablo.rodriguez@ctm.com.es [CTM - Technologic Centre, Materials Technology Area, Manresa, Cataluna (Spain); Department of Materials Science and Metallurgical Engineering, Universidad Politecnica de Cataluna, Barcelona (Spain); Houbaert, Yvan, E-mail: Yvan.Houbaert@UGent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Petrov, Roumen, E-mail: Roumen.Petrov@ugent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Kestens, Leo, E-mail: Leo.kestens@ugent.be [Department of Materials Science and Engineering, University of Ghent (Belgium); Colas, Rafael, E-mail: rafael.colas@uanl.edu.mx [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon (Mexico); Centro de Innovacion, Investigacion y Desarrollo en Ingenieria y Tecnologia, Universidad Autonoma de Nuevo Leon (Mexico)

    2012-10-15

    The microstructure and texture development during high temperature plane strain compression of 2% in weight silicon steel was studied. The tests were carried out at a constant strain rate of 5 s{sup -1} with reductions of 25, 35 and 75% at temperatures varying from 800 to 1100 Degree-Sign C. The changes in microstructure and texture were studied by means of scanning electron microscopy and electron backscattered diffraction. The microstructure close to the surface of the samples was equiaxed, which is attributed to the shear caused by friction, whereas that at the centre of the specimens was made of a mixture of elongated and fine equiaxed grains, the last ones attributed to the action of dynamic recovery followed by recrystallization. It was found that the volume fraction of these equiaxed grains augmented as reduction and temperature increased; a 0.7 volume fraction was accomplished with a 75% reduction at 1100 Degree-Sign C. The texture of the equiaxed and elongated grains was found to vary with the increase of deformation and temperature, as the {gamma}-fibre tends to disappear and the {alpha}-fibre to increase towards the higher temperature range. -- Highlights: Black-Right-Pointing-Pointer The plastic deformation of a silicon containing steel is studied by plane strain compression. Black-Right-Pointing-Pointer Equiaxed and elongated grains develop in different regions of the sample due to recrystallization. Black-Right-Pointing-Pointer Texture, by EBSD, is revealed to be similar in either type of grains.

  10. Electrochemical high-temperature gas sensors

    Science.gov (United States)

    Saruhan, B.; Stranzenbach, M.; Yüce, A.; Gönüllü, Y.

    2012-06-01

    Combustion produced common air pollutant, NOx associates with greenhouse effects. Its high temperature detection is essential for protection of nature. Component-integration capable high-temperature sensors enable the control of combustion products. The requirements are quantitative detection of total NOx and high selectivity at temperatures above 500°C. This study reports various approaches to detect NO and NO2 selectively under lean and humid conditions at temperatures from 300°C to 800°C. All tested electrochemical sensors were fabricated in planar design to enable componentintegration. We suggest first an impedance-metric gas sensor for total NOx-detection consisting of NiO- or NiCr2O4-SE and PYSZ-electrolyte. The electrolyte-layer is about 200μm thickness and constructed of quasi-single crystalline columns. The sensing-electrode (SE) is magnetron sputtered thin-layers of NiO or NiCr2O4. Sensor sensitivity for detection of total NOx has been measured by applying impedance analysis. The cross-sensitivity to other emission gases such as CO, CO2, CH4 and oxygen (5 vol.%) has been determined under 0-1000ppm NO. Sensor maintains its high sensitivity at temperatures up to 550°C and 600°C, depending on the sensing-electrode. NiO-SE yields better selectivity to NO in the presence of oxygen and have shorter response times comparing to NiCr2O4-SE. For higher temperature NO2-sensing capability, a resistive DC-sensor having Al-doped TiO2-sensing layers has been employed. Sensor-sensitivity towards NO2 and cross-sensitivity to CO has been determined in the presence of H2O at temperatures 600°C and 800°C. NO2 concentrations varying from 25 to 100ppm and CO concentrations from 25 to 75ppm can be detected. By nano-tubular structuring of TiO2, NO2 sensitivity of the sensor was increased.

  11. Low field magnetic measurements on high temperature superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Shaw, G.; Murphy, S.D.; Li, Z.Y.; Stewart, A.M.; Bhagat, S.M. (Maryland Univ., College Park, MD (USA). Dept. of Physics and Astronomy)

    1989-09-01

    The authors report dc magnetization and ac susceptibility measurements on both micron size powders and sintered samples of several high temperature superconductors. The powder data confirm previous findings that the materials can be treated as conventional superconductors with s-wave pairing. The ac results on sintered slabs ar interpreted using Bean's model and yield the temperature dependence of the shielding current.

  12. Why Do Deconfinement and Chiral Restoration Coincide at High Temperature?

    Institute of Scientific and Technical Information of China (English)

    杨树; 郭华; 赵恩广; 吕晓夫

    2004-01-01

    The global colour model in free space is extended to finite temperature to study the deconfinement and chiral phase transitions at high temperature T and zero chemical potential in the mean field approximation. Both possibilities of coincidence and non-coincidence of the two distinct phase transitions are found when the model parameters are varied in a certain range. The underlying mechanisms of the coincidence and noncoincidence are analysed and discussed. The validity of the T-dependent model propagator as the input is also discussed.

  13. High-temperature shock tube and modeling studies on the reactions of methanol with D-atoms and CH3-radicals.

    Science.gov (United States)

    Peukert, S L; Michael, J V

    2013-10-10

    The shock tube technique has been used to study the hydrogen abstraction reactions D + CH3OH → CH2O + H + HD (A) and CH3 + CH3OH → CH2O + H + CH4 (B). For reaction A, the experiments span a T-range of 1016 K ≤ T ≤ 1325 K, at pressures 0.25 bar ≤ P ≤ 0.46 bar. The experiments on reaction B, CH3 + CH3OH, cover a T-range of 1138 K ≤ T ≤ 1270 K, at pressures around 0.40 bar. Reflected shock tube experiments, monitoring the depletion of D-atoms by applying D-atom atomic resonance absorption spectrometry (ARAS), were performed on reaction A using gas mixtures of C2D5I and CH3OH in Kr bath gas. C2D5I was used as precursor for D-atoms. For reaction B, reflected shock tube experiments monitoring H-atom formation with H-ARAS, were carried out using gas mixtures of diacetyl ((CH3CO)2) and CH3OH in Kr bath gas. (CH3CO)2 was used as the source of CH3-radicals. Detailed reaction models were assembled to fit the D-atom and H-atom time profiles in order to obtain experimental rate constants for reactions A and B. Total rate constants from the present experiments on D + CH3OH and CH3 + CH3OH can be represented by the Arrhenius equations kA(T) = 1.51 × 10(-10) exp(-3843 K/T) cm(3) molecules(-1) s(-1) (1016 K ≤ T ≤ 1325 K) and kB(T) = 9.62 × 10(-12) exp(-7477 K/T) cm(3) molecules(-1) s(-1) (1138 K ≤ T ≤ 1270 K). The experimentally obtained rate constants were compared with available rate data from the literature. The results from quantum chemical studies on reaction A were found to be in good agreement with the present results. The present work represents the first direct experimental study on these bimolecular reactions at combustion temperatures and is important to the high-temperature oxidation of CH3OH.

  14. Pulse Radiolysis at High Temperatures and High Pressures

    DEFF Research Database (Denmark)

    Christensen, H.; Sehested, Knud

    1981-01-01

    A set-up enabling pulse radiolysis measurements at high temperatures (up to 320°C) and high pressures (up to 140 bar) has been constructed in collaboration between Risö National Laboratory and Studsvik Energiteknik. The cell has been used for experiments with aqueous solutions with the purpose...

  15. High temperature alloys: their exploitable potential

    Energy Technology Data Exchange (ETDEWEB)

    Marriott, J.B.; Merz, M.; Nihoul, J.; Ward, J. (eds.) (Commission of the European Communities, Petten (Netherlands). Joint Nuclear Research Center; NET-TEAM, Garching (DE))

    1987-01-01

    This book is the proceedings of a conference dealing with fundamental and technical aspects of the applications of high temperature alloys. It is split into five sections which cover the opening session of the conference and four further sessions covering: the theoretical and practical limits for HT alloys; the potential for development in alloys and processing; engineering considerations; the future outlook. The different sessions each included a number of invited papers followed by a series of posters and were concluded by a presentation of a 'synthesis' by a session rapporteur and general discussion. This structure is retained in the proceedings, including the discussion points in those cases where the authors have provided written answers to the questions raised. This book will be of interest to metallurgists, materials scientists, physicists and research workers in high temperature materials.

  16. High temperature and pressure electrochemical test station

    DEFF Research Database (Denmark)

    Chatzichristodoulou, Christodoulos; Allebrod, Frank; Mogensen, Mogens Bjerg

    2013-01-01

    An electrochemical test station capable of operating at pressures up to 100 bars and temperatures up to 400 ◦C has been established. It enables control of the partial pressures and mass flow of O2, N2, H2, CO2, and H2O in a single or dual environment arrangement, measurements with highly corrosive...... media, as well as localized sampling of gas evolved at the electrodes for gas analysis. A number of safety and engineering design challenges have been addressed. Furthermore, we present a series of electrochemical cell holders that have been constructed in order to accommodate different types of cells......, to the electrochemical characterization of high temperature and pressure alkaline electrolysis cells and the use of pseudo-reference electrodes for the separation of each electrode contribution. A future perspective of various electrochemical processes and devices that can be developed with the use of the established...

  17. High temperature superconductor materials and applications

    Science.gov (United States)

    Doane, George B., III. (Editor); Banks, Curtis; Golben, John

    1991-01-01

    One of the areas concerned itself with the investigation of the phenomena involved in formulating and making in the laboratory new and better superconductor material with enhanced values of critical current and temperature. Of special interest were the chemistry, physical processes, and environment required to attain these enhanced desirable characteristics. The other area concerned itself with producing high temperature superconducting thin films by pulsed laser deposition techniques. Such films are potentially very useful in the detection of very low power signals. To perform this research high vacuum is required. In the course of this effort, older vacuum chambers were maintained and used. In addition, a new facility is being brought on line. This latter activity has been replete with the usual problems of bringing a new facility into service. Some of the problems are covered in the main body of this report.

  18. High Temperature Phenomena in Shock Waves

    CERN Document Server

    2012-01-01

    The high temperatures generated in gases by shock waves give rise to physical and chemical phenomena such as molecular vibrational excitation, dissociation, ionization, chemical reactions and inherently related radiation. In continuum regime, these processes start from the wave front, so that generally the gaseous media behind shock waves may be in a thermodynamic and chemical non-equilibrium state. This book presents the state of knowledge of these phenomena. Thus, the thermodynamic properties of high temperature gases, including the plasma state are described, as well as the kinetics of the various chemical phenomena cited above. Numerous results of measurement and computation of vibrational relaxation times, dissociation and reaction rate constants are given, and various ionization and radiative mechanisms and processes are presented. The coupling between these different phenomena is taken into account as well as their interaction with the flow-field. Particular points such as the case of rarefied flows an...

  19. Metallic Membranes for High Temperature Hydrogen Separation

    DEFF Research Database (Denmark)

    Ma, Y.H.; Catalano, Jacopo; Guazzone, Federico

    2013-01-01

    Composite palladium membranes have extensively been studied in laboratories and, more recently, in small pilot industrial applications for the high temperature separation of hydrogen from reactant mixtures such as water-gas shift (WGS) reaction or methane steam reforming (MSR). Composite Pd...... membrane fabrication methods have matured over the last decades, and the deposition of very thin films (1–5 µm) of Pd over porous ceramics or modified porous metal supports is quite common. The H2 permeances and the selectivities achieved at 400–500 °C were in the order of 50–100 Nm3/m/h/bar0.5 and greater...... than 1000, respectively. This chapter describes in detail composite Pd-based membrane preparation methods, which consist of the grading of the support and the deposition of the dense metal layer, their performances, and their applications in catalytic membrane reactors (CMRs) at high temperatures (400...

  20. Temperature Buffer Test. Final THM modelling

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias; Malmberg, Daniel; Boergesson, Lennart; Hernelind, Jan [Clay Technology AB, Lund (Sweden); Ledesma, Alberto; Jacinto, Abel [UPC, Universitat Politecnica de Catalunya, Barcelona (Spain)

    2012-01-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modelling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aespoe HRL. It was installed during the spring of 2003. Two heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by bentonite only, whereas the upper heater was surrounded by a composite barrier, with a sand shield between the heater and the bentonite. The test was dismantled and sampled during the winter of 2009/2010. This report presents the final THM modelling which was resumed subsequent to the dismantling operation. The main part of this work has been numerical modelling of the field test. Three different modelling teams have presented several model cases for different geometries and different degree of process complexity. Two different numerical codes, Code{sub B}right and Abaqus, have been used. The modelling performed by UPC-Cimne using Code{sub B}right, has been divided in three subtasks: i) analysis of the response observed in the lower part of the test, by inclusion of a number of considerations: (a) the use of the Barcelona Expansive Model for MX-80 bentonite; (b) updated parameters in the vapour diffusive flow term; (c) the use of a non-conventional water retention curve for MX-80 at high temperature; ii) assessment of a possible relation between the cracks observed in the bentonite blocks in the upper part of TBT, and the cycles of suction and stresses registered in that zone at the start of the experiment; and iii) analysis of the performance, observations and interpretation of the entire test. It was however not possible to carry out a full THM analysis until the end of the test due to

  1. Temperature Buffer Test. Final THM modelling

    Energy Technology Data Exchange (ETDEWEB)

    Aakesson, Mattias; Malmberg, Daniel; Boergesson, Lennart; Hernelind, Jan [Clay Technology AB, Lund (Sweden); Ledesma, Alberto; Jacinto, Abel [UPC, Universitat Politecnica de Catalunya, Barcelona (Spain)

    2012-01-15

    The Temperature Buffer Test (TBT) is a joint project between SKB/ANDRA and supported by ENRESA (modelling) and DBE (instrumentation), which aims at improving the understanding and to model the thermo-hydro-mechanical behavior of buffers made of swelling clay submitted to high temperatures (over 100 deg C) during the water saturation process. The test has been carried out in a KBS-3 deposition hole at Aespoe HRL. It was installed during the spring of 2003. Two heaters (3 m long, 0.6 m diameter) and two buffer arrangements have been investigated: the lower heater was surrounded by bentonite only, whereas the upper heater was surrounded by a composite barrier, with a sand shield between the heater and the bentonite. The test was dismantled and sampled during the winter of 2009/2010. This report presents the final THM modelling which was resumed subsequent to the dismantling operation. The main part of this work has been numerical modelling of the field test. Three different modelling teams have presented several model cases for different geometries and different degree of process complexity. Two different numerical codes, Code{sub B}right and Abaqus, have been used. The modelling performed by UPC-Cimne using Code{sub B}right, has been divided in three subtasks: i) analysis of the response observed in the lower part of the test, by inclusion of a number of considerations: (a) the use of the Barcelona Expansive Model for MX-80 bentonite; (b) updated parameters in the vapour diffusive flow term; (c) the use of a non-conventional water retention curve for MX-80 at high temperature; ii) assessment of a possible relation between the cracks observed in the bentonite blocks in the upper part of TBT, and the cycles of suction and stresses registered in that zone at the start of the experiment; and iii) analysis of the performance, observations and interpretation of the entire test. It was however not possible to carry out a full THM analysis until the end of the test due to

  2. High temperature mechanical properties of iron aluminides

    Directory of Open Access Journals (Sweden)

    Morris, D. G.

    2001-04-01

    Full Text Available Considerable attention has been given to the iron aluminide family of intermetallics over the past years since they offer considerable potential as engineering materials for intermediate to high temperature applications, particularly in cases where extreme oxidation or corrosion resistance is required. Despite efforts at alloy development, however, high temperature strength remains low and creep resistance poor. Reasons for the poor high-temperature strength of iron aluminides will be discussed, based on the ordered crystal structure, the dislocation structure found in the material, and the mechanisms of dislocation pinning operating. Alternative ways of improving high temperature strength by microstructural modification and the inclusion of second phase particles will also be considered.

    Durante los últimos años se ha prestado mucha atención a la familia de intermetálicos Fe-Al, puesto que estos constituyen un considerable potencial como materiales de ingeniería en aplicaciones a temperaturas intermedias o altas, sobre todo en casos donde se necesita alta resistencia a la oxidación o corrosión. A pesar del considerable esfuerzo desarrollado para obtener aleaciones con mejores propiedades, su resistencia mecánica a alta temperatura no es muy elevada. Se discutirán los aspectos que contribuyen a la baja resistencia mecánica a temperatura elevada en función de la estructura de dislocaciones y los mecanismos de anclaje que operan en este intermetálico. Se considerarán, también, maneras alternativas para mejorar la resistencia a temperatura elevada mediante la modificación de la microestructura y la incorporación de partículas de segunda fase.

  3. High Temperature Perforating System for Geothermal Applications

    Energy Technology Data Exchange (ETDEWEB)

    Smart, Moises E. [Schlumberger Technology Corporation, Sugar Land, TX (United States)

    2017-02-28

    The objective of this project is to develop a perforating system consisting of all the explosive components and hardware, capable of reliable performance in high temperatures geothermal wells (>200 ºC). In this light we will focused on engineering development of these components, characterization of the explosive raw powder and developing the internal infrastructure to increase the production of the explosive from laboratory scale to industrial scale.

  4. On quark number susceptibilities at high temperatures

    CERN Document Server

    Bazavov, A; Hegde, P; Karsch, F; Miao, C; Mukherjee, Swagato; Petreczky, P; Schmidt, C; Velytsky, A

    2013-01-01

    We calculated second and fourth order quark number susceptibilities for 2+1 flavor QCD in the high temperature region using two improved staggered fermion formulations. The calculations are performed at several lattice spacing and we show that in the continuum limit the two formulations give consistent results. We compare our continuum extrapolated results on quark number susceptibilities with recent weak coupling calculations, and find that these cannot simultaneously explain the lattice results for second and fourth order quark number susceptibilities.

  5. Intermetallic-based high-temperature materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.

    1999-07-01

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminides are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  6. Intermetallic-Based High-Temperature Materials

    Energy Technology Data Exchange (ETDEWEB)

    Sikka, V.K.

    1999-04-25

    The intermetallic-based alloys for high-temperature applications are introduced. General characteristics of intermetallics are followed by identification of nickel and iron aluminides as the most practical alloys for commercial applications. An overview of the alloy compositions, melting processes, and mechanical properties for nickel and iron aluminizes are presented. The current applications and commercial producers of nickel and iron aluminizes are given. A brief description of the future prospects of intermetallic-based alloys is also given.

  7. Hydrogen dominant metallic alloys: high temperature superconductors?

    Science.gov (United States)

    Ashcroft, N W

    2004-05-07

    The arguments suggesting that metallic hydrogen, either as a monatomic or paired metal, should be a candidate for high temperature superconductivity are shown to apply with comparable weight to alloys of metallic hydrogen where hydrogen is a dominant constituent, for example, in the dense group IVa hydrides. The attainment of metallic states should be well within current capabilities of diamond anvil cells, but at pressures considerably lower than may be necessary for hydrogen.

  8. High Temperature Superconducting Maglev Measurement System

    OpenAIRE

    Wang, Jia-Su; Wang, Su-Yu

    2010-01-01

    Three high temperature superconducting (HTS) Maglev measurement systems were successfully developed in the Applied Superconductivity Laboratory (ASCLab) of Southwest Jiaotong University, P. R. China. These systems include liquid nitrogen vessel, Permanent Magnet Guideway (PMG), data collection and processing, mechanical drive and Autocontrol features. This chapter described the three different measuring systems along with their theory of operations and workflow. The SCML-01 HTS Maglev measure...

  9. GRAPHENE PEEK COMPOSITES AS HIGH TEMPERATURE ADHESIVES

    Science.gov (United States)

    2017-09-05

    Price DW, Roberts JA, Scott JB, Wadhawan A, Ye Z, Tour JM. Nanotubes in microwave fields : light emission , intense heat, outgassing, and reconstruction...Arepalli S, Yowell LL, Tour JM. Carbon nanotube composite curing through absorption of microwave radiation. Composites Science and Technology. 2008 Dec...polymer that is suitable for high-temperature applications. Graphene is a two-dimensional form of carbon nanomaterial that has been studied

  10. Technological evolution of high temperature superconductors

    OpenAIRE

    White, Jordan R.

    2015-01-01

    Approved for public release; distribution is unlimited High temperature superconducting (HTS) cables are currently being used in the commercial energy industry primarily for demonstration purposes and to evaluate the feasibility of large-scale implementation into the electric grid. While still in the evaluation stage, the U.S. Navy is finding the test results promising and is investigating its potential use for future electric ships to supply power to electric propulsion motors and possibl...

  11. Development of High-Temperature Strain Gages.

    Science.gov (United States)

    1961-03-17

    lengths the article is either dipped in a slip (finely divided tend to require a support for the grid, while shorter coating material suspended in a...liquid) or the lengths require too many loops to achieve the slip is sprayed onto the article , followed in both cases by high-temperature fusion. An...Electrochemistry. Electrical Instruments. Magnetic Measurements. Dielectrics. Metrology. Photometry and Colorimetry. Refractometry . Photographic Research

  12. NUMERICAL SIMULATION OF CAVITATION FLOW UNDER HIGH PRESSURE AND TEMPERATURE

    Institute of Scientific and Technical Information of China (English)

    ZHAO Wei-guo; ZHANG Ling-xin; SHAO Xue-ming

    2011-01-01

    The numerical simulation of cavitation flow on a 2D NACA0015 hydrofoil under high pressure and temperature is performed. The Singhal's cavitation model is adopted combined with an improved RNG k-ε turbulence model to study the cavitation flow. The thermal effect in the cavitation flow is taken into account by introducing the energy equation with a source term based on the latent heat transfer. The code is validated by a case of a hydrofoil under two different temperatures in a comparison between the simulation and the experiment. Computational results show that the latent heat of vaporization has a significant impact on the cavitation process in the high temperature state, and the cavity in the high temperature state is thinner and shorter than that in a normal state with the same cavitation number, due to the fact that the heat absorption in the cavitation area reduces the local temperature and the saturated vapor pressure. This numerical study provides some guidance for the design of machineries in the High Pressure and Temperature (HPT) state.

  13. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed electromagnets only. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  14. Novel High Temperature Magnetic Bearings for Space Vehicle Systems Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Previous high temperature magnetic bearings employed only electromagnets. The work proposed in this SBIR program seeks to utilize High Temperature Permanent Magnets...

  15. The NDT methods under high temperature service environment

    Directory of Open Access Journals (Sweden)

    Zhang Zhen-guo

    2016-01-01

    Full Text Available Concerning the detective requirement of the equipment under high temperature running status, this paper summarizes the technical characteristics and related applications of several non-destructive testing methods(NDT, such as thermal infrared imaging technology in high temperature, ultrasonic testing technique in high temperature, pulsed eddy current technology in high temperature and magnetic powder flaw detection technology in high temperature, penetration testing technique in high temperature and indirect visual detection in high temperature and on-line monitoring system in high temperature.

  16. High-Temperature Cuprate Superconductors Experiment, Theory, and Applications

    CERN Document Server

    Plakida, Nikolay Maksimilianovich

    2010-01-01

    High-Temperature Cuprate Superconductors provides an up-to-date and comprehensive review of the properties of these fascinating materials. The essential properties of high-temperature cuprate superconductors are reviewed on the background of their theoretical interpretation. The experimental results for structural, magnetic, thermal, electric, optical and lattice properties of various cuprate superconductors are presented with respect to relevant theoretical models. A critical comparison of various theoretical models involving strong electron correlations, antiferromagnetic spin fluctuations, phonons and excitons provides a background for understanding of the mechanism of high-temperature superconductivity. Recent achievements in their applications are also reviewed. A large number of illustrations and tables gives valuable information for specialists. A text-book level presentation with formulation of a general theory of strong-coupling superconductivity will help students and researches to consolidate their...

  17. Study on a transient optical fiber high temperature measurement system

    Science.gov (United States)

    Cai, Lulu; Liu, Yusha; Wang, Yutian

    2009-07-01

    High temperature is one of the most important parameters in the fields of scientific research and industrial production. At present, thermocouple, thermo resistive and radiance thermometer are already technologically mature which can be adopted to measure the general temperature, but when it comes to the transient high temperature that changes pretty quickly in wretched conditions, those traditional pyrometers can not meet the requirements any more. In this paper, we designed a transient optical high temperature measurement system. First, design of the temperature measurement probe. The system took blackbody cavity sensor together with optical fiber to receive the measured signal, here, the integrated emissivity model of the blackbody cavity was established and the optimum structure parameters were confirmed. Secondly, design of the entire temperature measurement system. A contact-noncontact measurement method was applied, which is to make the blackbody cavity and the measured high-temperature source contact, the fiber probe and the blackbody cavity noncontact, as a result, the error caused by contact measurement is overcame and the precision is guaranteed at the same time. In addition, a fiber grating was introduced as the wavelength filter device which can realize the dynamic filter of narrow-band signals and reduce the impact of background light. Thirdly, signal processing. In this part, we applied labVIEW software and wavelet analysis method. All of the signal acquisition and processing were realized in the labVIEW environment. Through calling matlab in labVIEW, the signals from optical fiber detector were wavelet denoised and decomposed, thus the temperature information was extracted, and the temperature value was obtained. On basis of wavelet transformation, the paper adopted the 4dB wavelet with horizontal scale of 5 to realize the feature extraction and noise removal, parts of the signals before and after the wavelet noise removal were given and analyzed

  18. Technology of high-temperature organic coolant

    Energy Technology Data Exchange (ETDEWEB)

    Vorobei, M.P.; Makin, R.S.; Kuprienko, V.A. [and others

    1993-12-31

    A wide range of studies were carried out in RIAR on the problems connected with the use of high-temperature organic coolant at nuclear power plants. The work performed and successful experience gained in persistent operation of the ARBUS reactor confirmed the inherent safety characteristics, high operational reliability, as well as improved safety of stations with similar reactors. A large scope of studies were carried out at the ARBUS pilot reactor and loop with the organic coolant of the MIR reactor and a wide range of problems were solved. The studies are described.

  19. Precipitation Hardenable High Temperature Shape Memory Alloy

    Science.gov (United States)

    Noebe, Ronald Dean (Inventor); Draper, Susan L. (Inventor); Nathal, Michael V. (Inventor); Crombie, Edwin A. (Inventor)

    2010-01-01

    A composition of the invention is a high temperature shape memory alloy having high work output, and is made from (Ni+Pt+Y),Ti(100-x) wherein x is present in a total amount of 49-55 atomic % Pt is present in a total amount of 10-30 atomic %, Y is one or more of Au, Pd. and Cu and is present in a total amount of 0 to 10 atomic %. The alloy has a matrix phase wherein the total concentration of Ni, Pt, and the one or more of Pd. Au, and Cu is greater than 50 atomic %.

  20. High Temperature Sensing Systems--Characteristics of Rechargeable Batteries at High Temperature--

    OpenAIRE

    2001-01-01

     High temperature discharge characteristics were measured at 100℃ for commercial available Nickel Cadmium and Nickel Metal Hydride rechargeable batteries. A Nickel Cadmium battery has superior dis­charge characteristics than a Nickel Metal Hydride battery. A life cycle of rechargeable battery can be esti­mated by measuring an internal resistance of the battery during charge at room temperature.