WorldWideScience

Sample records for high-temperature thermal insulation

  1. Thermal insulation of high temperature reactors

    International Nuclear Information System (INIS)

    Cornille, Y.

    1975-01-01

    Operating conditions of HTR thermal insulation are given and heat insulators currently developed are described (fibers kept in position by metallic structures). For future applications and higher temperatures, research is directed towards solutions using ceramics or associating fibers and ceramics [fr

  2. Thermal insulation of the high-temperature helium-cooled reactors

    International Nuclear Information System (INIS)

    Kharlamov, A.G.; Grebennik, V.N.

    1979-01-01

    Unlike the well-known thermal insulation methods, development of high-temperature helium reactors (HTGR) raises quite new problems. To understand these problems, it is necessary to consider behaviour of thermal insulation inside the helium circuit of HTGR and requirements imposed on it. Substantiation of these requirements is given in the presented paper

  3. Simultaneous reconstruction of thermal degradation properties for anisotropic scattering fibrous insulation after high temperature thermal exposures

    International Nuclear Information System (INIS)

    Zhao, Shuyuan; Zhang, Wenjiao; He, Xiaodong; Li, Jianjun; Yao, Yongtao; Lin, Xiu

    2015-01-01

    To probe thermal degradation behavior of fibrous insulation for long-term service, an inverse analysis model was developed to simultaneously reconstruct thermal degradation properties of fibers after thermal exposures from the experimental thermal response data, by using the measured infrared spectral transmittance and X-ray phase analysis data as direct inputs. To take into account the possible influence of fibers degradation after thermal exposure on the conduction heat transfer, we introduced a new parameter in the thermal conductivity model. The effect of microstructures on the thermal degradation parameters was evaluated. It was found that after high temperature thermal exposure the decay rate of the radiation intensity passing through the material was weakened, and the probability of being scattered decreased during the photons traveling in the medium. The fibrous medium scattered more radiation into the forward directions. The shortened heat transfer path due to possible mechanical degradation, along with the enhancement of mean free path of phonon scattering as devitrification after severe heat treatment, made the coupled solid/gas thermal conductivities increase with the rise of heat treatment temperature. - Highlights: • A new model is developed to probe conductive and radiative properties degradation of fibers. • To characterize mechanical degradation, a new parameter is introduced in the model. • Thermal degradation properties are reconstructed from experiments by L–M algorithm. • The effect of microstructures on the thermal degradation parameters is evaluated. • The analysis provides a powerful tool to quantify thermal degradation of fiber medium

  4. Control performances of a piezoactuator direct drive valve system at high temperatures with thermal insulation

    Science.gov (United States)

    Han, Yung-Min; Han, Chulhee; Kim, Wan Ho; Seong, Ho Yong; Choi, Seung-Bok

    2016-09-01

    This technical note presents control performances of a piezoactuator direct drive valve (PDDV) operated at high temperature environment. After briefly discussing operating principle and mechanical dimensions of the proposed PDDV, an appropriate size of the PDDV is manufactured. As a first step, the temperature effect on the valve performance is experimentally investigated by measuring the spool displacement at various temperatures. Subsequently, the PDDV is thermally insulated using aerogel and installed in a large-size heat chamber in which the pneumatic-hydraulic cylinders and sensors are equipped. A proportional-integral-derivative feedback controller is then designed and implemented to control the spool displacement of the valve system. In this work, the spool displacement is chosen as a control variable since it is directly related to the flow rate of the valve system. Three different sinusoidal displacements with different frequencies of 1, 10 and 50 Hz are used as reference spool displacement and tracking controls are undertaken up to 150 °C. It is shown that the proposed PDDV with the thermal insulation can provide favorable control responses without significant tracking errors at high temperatures.

  5. High temperature resistant cermet and ceramic compositions. [for thermal resistant insulators and refractory coatings

    Science.gov (United States)

    Phillips, W. M. (Inventor)

    1978-01-01

    High temperature oxidation resistance, high hardness and high abrasion and wear resistance are properties of cermet compositions particularly to provide high temperature resistant refractory coatings on metal substrates, for use as electrical insulation seals for thermionic converters. The compositions comprise a sintered body of particles of a high temperature resistant metal or metal alloy, preferably molybdenum or tungsten particles, dispersed in and bonded to a solid solution formed of aluminum oxide and silicon nitride, and particularly a ternary solid solution formed of a mixture of aluminum oxide, silicon nitride and aluminum nitride. Ceramic compositions comprising a sintered solid solution of aluminum oxide, silicon nitride and aluminum nitride are also described.

  6. Nuclear reactor pressure vessel with an inner metal coating covered with a high temperature resistant thermal insulator

    International Nuclear Information System (INIS)

    1974-01-01

    The thermal insulator covering the metal coating of a reactor vessel is designed for resisting high temperatures. It comprises one or several porous layers of ceramic fibers or of stacked metal foils, covered with a layer of bricks or ceramic tiles. The latter are fixed in position by fasteners comprising pins fixed to the coating and passing through said porous layers and fasteners (nut or bolts) for individually fixing the bricks to said pins, whereas ceramic plugs mounted on said bricks or tiles provide for the thermal insulation of the pins and of the nuts or bolts; such a thermal insulation can be applied to high-temperature reactors or to fast reactors [fr

  7. Absolute measurement of the thermal conductivity of insulating materials at high temperature

    International Nuclear Information System (INIS)

    Liermann, J.

    1975-01-01

    A device was developed at the CEA for the absolute measurement of the thermal conductivity of insulators. It can operate in controlled atmospheres (air, CO 2 , Ar, He) and between 100 and 1050 deg C [fr

  8. Thermal insulation

    International Nuclear Information System (INIS)

    Aspden, G.J.; Howard, R.S.

    1988-01-01

    The patent concerns high temperature thermal insulation of large vessels, such as the primary vessel of a liquid metal cooled nuclear reactor. The thermal insulation consists of multilayered thermal insulation modules, and each module comprises a number of metal sheet layers sandwiched between a back and front plate. The layers are linked together by straps and clips to control the thickness of the module. (U.K.)

  9. Thermal insulation

    International Nuclear Information System (INIS)

    Pinsky, G.P.

    1977-01-01

    Thermal insulation for vessels and piping within the reactor containment area of nuclear power plants is disclosed. The thermal insulation of this invention can be readily removed and replaced from the vessels and piping for inservice inspection, can withstand repeated wettings and dryings, and can resist high temperatures for long periods of time. 4 claims, 3 figures

  10. Colloquium 3: Thermal insulation materials in construction and in high-temperature plants. Lectures; Kolloquium 3: Waermedaemmstoffe im Bauwesen und in Hochtemperaturanlagen. Vortraege

    Energy Technology Data Exchange (ETDEWEB)

    Schlegel, E.; Gross, U.; Walter, G. [comps.

    1999-07-01

    Colloquium 3, ''Thermal insulation materials in construction and in high-temperature plants'' focused, for one thing, on the inter-relationships between the development of thermal insulation materials for construction and high-temperature applications and the development of processes and plants and, for another, on the standards of and amendments to the thermal protection ordinance. Calcium silicate and Silcapor as a thermal protection material and a high-temperature thermal insulant, respectively, are dealt with inter alia. The use of thermal insulants in industrial furnaces and different methods for measuring thermal conductivity are described. Further topics are the elements of the energy conservation ordinance being drafted, and thermal-insulation construction materials such as bricks and foam mortar. Ten papers are individually listed in the Energy database. (orig.) [German] Im Mittelpunkt des Kolloquium 3 ''Waermedaemmstoffe im Bauwesen und in Hochtemperaturanlagen'' stehen die wechselseitigen Zusammenhaenge zwischen der Entwicklung von Waermedaemmstoffen fuer das Bauwesen und die Hochtemperaturanwendung einerseits und der Prozess-und Anlagenentwicklung anderseits sowie die Normung und die Novellierung der Waermeschutzverordnung. Es wird u.a. auf den Waermedaemmstoff Calciumsilicat eingegangen ebensowie auf Silcapor als Hochtemperaturd ammstoff. Der Einsatz von Waermedaemmstoffen in Industrieoefen sowie die unterschiedlichen Messmethoden der Waermeleitfaehigkeit werden beschrieben. Weitere Themen sind die Grundlagen der kuenftigen Energiesparverordnung sowie waermedaemmende Baustoffe wie Ziegel und Porenbeton. Fuer die Datenbank Energy wurden zehn Arbeiten separat aufgenommen.

  11. A novel highly porous ceramic foam with efficient thermal insulation and high temperature resistance properties fabricated by gel-casting process

    Science.gov (United States)

    Yu, Jiahong; Wang, Guixiang; Tang, Di; Qiu, Ya; Sun, Nali; Liu, Wenqiao

    2018-01-01

    The design of super thermal insulation and high-temperature resistant materials for high temperature furnaces is crucial due to the energy crisis and the huge wasting. Although it is told that numerous studies have been reported about various of thermal insulation materials prepared by different methods, the applications of yttria-stabilized zirconia (YSZ) ceramic foams fabricated through tert-butyl alcohol (TBA)-based gel-casting process in bulk thermal isolators were barely to seen. In this paper, highly porous yttria-stabilized zirconia (YSZ) ceramic foams were fabricated by a novel gel-casting method using tert-butyl alcohol (TBA) as solvent and pore-forming agent. Different raw material ratio, sintering temperature and soaking time were all investigated to achieve optimal thermal insulation and mechanical properties. We can conclude that porosity drops gradually while compressive strength increases significantly with the rising temperature from 1000-1500°C. With prolonged soaking time, there is no obvious change in porosity but compressive strength increases gradually. All specimens have uniformly distributed pores with average size of 0.5-2μm and show good structural stability at high temperature. The final obtained ceramic foams displayed an outstanding ultra-low thermal conductivity property with only 200.6 °C in cold surface while the hot side was 1000 °C (hold 60 min to keep thermal balance before testing) at the thickness of 10 mm.

  12. Natural convection of high-temperature, high-pressure gas in a horizontal annular layer of thermal insulator, (1)

    International Nuclear Information System (INIS)

    Ogawa, Masuro; Takizuka, Takakazu; Sanokawa, Konomo

    1979-02-01

    Numerical calculations are described of the natural convection in a horizontal annular layer of thermal insulator. The purpose is to compare the numerical results for variable physical properties with those for constant properties. The numerical procedure and typical results are presented. (author)

  13. Survey of thermal insulation systems

    International Nuclear Information System (INIS)

    Kinoshita, Izumi

    1983-01-01

    Better thermal insulations have been developed to meet the growing demands of industry, and studies on thermal insulation at both high temperature and low temperature have been widely performed. The purpose of this survey is to summarize data on the performances and characteristics of thermal insulation materials and thermal insulation structures (for instance, gas cooled reactors, space vehicles and LNG storage tanks), and to discuss ravious problems regarding the design of thermal insulation structures of pool-type LMFBRs. (author)

  14. Hydrothermal hardened high-temperature thermal insulation material CALUTHERM {sup registered} from hibonite and alumina cement. Pt. 1; Hydrothermal erhaerteter Hochtemperaturwaermedaemmstoff CALUTHERM {sup registered} aus Hibonit und Tonerdezement. T. 1

    Energy Technology Data Exchange (ETDEWEB)

    Hoelscher, Tobias; Schneider, Hans-Juergen [Calsitherm Silikatbaustoffe GmbH, Bad Lippspringe (Germany); Schlegel, Ernst

    2013-07-01

    The first part features an overview to the properties of all calcium aluminates followed by a presentation of CALUTHERM {sup registered}, a high temperature-thermal insulating material. CALUTHERM is produced on the bases of SLA-92, a calcium hexaaluminat aggregate, and calcium aluminate cement CA-14 W as binder. The comprehensive studies focus on properties and changes of these raw materials during the technological stages of the CALUTHERM's production. The second part will present CALUTHERM's properties and its variants throughout the production process. A possible correlation between the properties of raw materials and thermal insulation material is researched and finally application examples are presented. CALUTHERM is suited for thermal insulation up to 1600 C and has a remarkable low thermal conductivity near 0.4 W/m . K at these high temperatures. For that reason CALUTHERM is a top high-temperature thermal insulating material. (orig.)

  15. Thermal insulation

    International Nuclear Information System (INIS)

    Durston, J.G.; Birch, W.; Facer, R.I.; Stuart, R.A.

    1977-01-01

    Reference is made to liquid metal cooled nuclear reactors. In the arrangement described the reactor vessel is clad with thermal insulation comprising a layer of insulating blocks spaced from the wall and from each other; each block is rigidly secured to the wall, and the interspaces are substantially closed against convectional flow of liquid by resilient closure members. A membrane covering is provided for the layer of blocks, with venting means to allow liquid from the reactor vessel to penetrate between the covering and the layer of blocks. The membrane covering may comprise a stainless steel sheet ribbed in orthogonal pattern to give flexibility for the accommodation of thermal strain. The insulating blocks may be comprised of stainless steel or cellular or porous material and may be hollow shells containing ceramic material or gas fillings. (U.K.)

  16. 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.

  17. Thermal diffusivity of electrical insulators at high temperatures: Evidence for diffusion of bulk phonon-polaritons at infrared frequencies augmenting phonon heat conduction

    Science.gov (United States)

    Hofmeister, Anne M.; Dong, Jianjun; Branlund, Joy M.

    2014-04-01

    We show that laser-flash analysis measurements of the temperature (T) dependence of thermal diffusivity (D) for diverse non-metallic (e.g., silicates) single-crystals is consistently represented by D(T) = FT-G + HT above 298 K, with G ranging from 0.3 to 2, depending on structure, and H being ˜10-4 K-1 for 51 single-crystals, 3 polycrystals, and two glasses unaffected by disorder or reconstructive phase transitions. Materials exhibiting this behavior include complex silicates with variable amounts of cation disorder, perovskite structured materials, and graphite. The high-temperature term HT becomes important by ˜1300 K, above which temperature its contribution to D(T) exceeds that of the FT-G term. The combination of the FT-G and HT terms produces the nearly temperature independent high-temperature region of D previously interpreted as the minimal phonon mean free path being limited by the finite interatomic spacing. Based on the simplicity of the fit and large number of materials it represents, this finding has repercussions for high-temperature models of heat transport. One explanation is that the two terms describing D(T) are associated with two distinct microscopic mechanisms; here, we explore the possibility that the thermal diffusivity of an electrical insulator could include both a contribution of lattice phonons (the FT-G term) and a contribution of diffusive bulk phonon-polaritons (BPP) at infrared (IR) frequencies (the HT term). The proposed BPP diffusion exists over length scales smaller than the laboratory sample sizes, and transfers mixed light and vibrational energy at a speed significantly smaller than the speed of light. Our diffusive IR-BPP hypothesis is consistent with other experimental observations such as polarization behavior, dependence of D on the number of IR peaks, and H = 0 for Ge and Si, which lack IR fundamentals. A simple quasi-particle thermal diffusion model is presented to begin understanding the contribution from bulk phonon

  18. High Temperature Electrical Insulation Materials for Space Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — NASA's future space science missions cannot be realized without the state of the art high temperature insulation materials of which higher working temperature, high...

  19. Aerogel-Based Insulation for High-Temperature Industrial Processes

    Energy Technology Data Exchange (ETDEWEB)

    Dr. Owen Evans

    2011-10-13

    Under this program, Aspen Aerogels has developed an industrial insulation called Pyrogel HT, which is 4-5 times more thermally efficient than current non-aerogel technology. Derived from nanoporous silica aerogels, Pyrogel HT was specifically developed to address a high temperature capability gap not currently met with Aspen Aerogels{trademark} flagship product, Pyrogel XT. Pyrogel XT, which was originally developed on a separate DOE contract (DE-FG36-06GO16056), was primarily optimized for use in industrial steam processing systems, where application temperatures typically do not exceed 400 C. At the time, further improvements in thermal performance above 400 C could not be reasonably achieved for Pyrogel XT without significantly affecting other key material properties using the current technology. Cumulative sales of Pyrogel HT into domestic power plants should reach $125MM through 2030, eventually reaching about 10% of the total insulation market share in that space. Global energy savings would be expected to scale similarly. Over the same period, these sales would reduce domestic energy consumption by more than 65 TBtu. Upon branching out into all industrial processes in the 400 C-650 C regime, Pyrogel HT would reach annual sales levels of $150MM, with two-thirds of that being exported.

  20. 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.

  1. Economically optimal thermal insulation

    Energy Technology Data Exchange (ETDEWEB)

    Berber, J.

    1978-10-01

    Exemplary calculations to show that exact adherence to the demands of the thermal insulation ordinance does not lead to an optimal solution with regard to economics. This is independent of the mode of financing. Optimal thermal insulation exceeds the values given in the thermal insulation ordinance.

  2. Calculation of high-temperature insulation parameters and heat transfer behaviors of multilayer insulation by inverse problems method

    Directory of Open Access Journals (Sweden)

    Huang Can

    2014-08-01

    Full Text Available In the present paper, a numerical model combining radiation and conduction for porous materials is developed based on the finite volume method. The model can be used to investigate high-temperature thermal insulations which are widely used in metallic thermal protection systems on reusable launch vehicles and high-temperature fuel cells. The effective thermal conductivities (ECTs which are measured experimentally can hardly be used separately to analyze the heat transfer behaviors of conduction and radiation for high-temperature insulation. By fitting the effective thermal conductivities with experimental data, the equivalent radiation transmittance, absorptivity and reflectivity, as well as a linear function to describe the relationship between temperature and conductivity can be estimated by an inverse problems method. The deviation between the calculated and measured effective thermal conductivities is less than 4%. Using the material parameters so obtained for conduction and radiation, the heat transfer process in multilayer thermal insulation (MTI is calculated and the deviation between the calculated and the measured transient temperatures at a certain depth in the multilayer thermal insulation is less than 6.5%.

  3. Local Thermal Insulating Materials For Thermal Energy Storage ...

    African Journals Online (AJOL)

    Thermal insulation is one of the most important components of a thermal energy storage system. In this paper the thermal properties of selected potential local materials which can be used for high temperature insulation are presented. Thermal properties of seven different samples were measured. Samples consisted of: ...

  4. A high-temperature silicon-on-insulator stress sensor

    International Nuclear Information System (INIS)

    Wang Zheyao; Tian Kuo; Zhou Youzheng; Pan Liyang; Liu Litian; Hu Chaohong

    2008-01-01

    A piezoresistive stress sensor is developed using silicon-on-insulator (SOI) wafers and calibrated for stress measurement for high-temperature applications. The stress sensor consists of 'silicon-island-like' piezoresistor rosettes that are etched on the SOI layer. This eliminates leakage current and enables excellent electrical insulation at high temperature. To compensate for the measurement errors caused by the misalignment of the piezoresistor rosettes with respect to the crystallographic axes, an anisotropic micromachining technique, tetramethylammonium hydroxide etching, is employed to alleviate the misalignment issue. To realize temperature-compensated stress measurement, a planar diode is fabricated as a temperature sensor to decouple the temperature information from the piezoresistors, which are sensitive to both stress and temperature. Design, fabrication and calibration of the piezoresistors are given. SOI-related characteristics such as piezoresistive coefficients and temperature coefficients as well as the influence of the buried oxide layer are discussed in detail

  5. Thermal insulating panel

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, J.T.

    1985-09-11

    A panel of thermal insulation material has at least one main portion which comprises a dry particulate insulation material compressed within a porous envelope so that it is rigid or substantially rigid and at least one auxiliary portion which is secured to and extends along at least one of the edges of the main portions. The auxiliary portions comprise a substantially uncompressed dry particulate insulation material contained within an envelope. The insulation material of the auxiliary portion may be the same as or may be different from the insulation material of the main portion. The envelope of the auxiliary portion may be made of a porous or a non-porous material. (author).

  6. Combined Heat Transfer in High-Porosity High-Temperature Fibrous Insulations: Theory and Experimental Validation

    Science.gov (United States)

    Daryabeigi, Kamran; Cunnington, George R.; Miller, Steve D.; Knutson, Jeffry R.

    2010-01-01

    Combined radiation and conduction heat transfer through various high-temperature, high-porosity, unbonded (loose) fibrous insulations was modeled based on first principles. The diffusion approximation was used for modeling the radiation component of heat transfer in the optically thick insulations. The relevant parameters needed for the heat transfer model were derived from experimental data. Semi-empirical formulations were used to model the solid conduction contribution of heat transfer in fibrous insulations with the relevant parameters inferred from thermal conductivity measurements at cryogenic temperatures in a vacuum. The specific extinction coefficient for radiation heat transfer was obtained from high-temperature steady-state thermal measurements with large temperature gradients maintained across the sample thickness in a vacuum. Standard gas conduction modeling was used in the heat transfer formulation. This heat transfer modeling methodology was applied to silica, two types of alumina, and a zirconia-based fibrous insulation, and to a variation of opacified fibrous insulation (OFI). OFI is a class of insulations manufactured by embedding efficient ceramic opacifiers in various unbonded fibrous insulations to significantly attenuate the radiation component of heat transfer. The heat transfer modeling methodology was validated by comparison with more rigorous analytical solutions and with standard thermal conductivity measurements. The validated heat transfer model is applicable to various densities of these high-porosity insulations as long as the fiber properties are the same (index of refraction, size distribution, orientation, and length). Furthermore, the heat transfer data for these insulations can be obtained at any static pressure in any working gas environment without the need to perform tests in various gases at various pressures.

  7. Research on material of high temperature cable and wire insulation by γ-rays

    International Nuclear Information System (INIS)

    Jia Shaojin; Zhang Zhicheng; Xu Xiangling; Ge Xuewu; Ye qiang; Wang Feng

    2000-01-01

    Radiation-crosslinking improves a number of essential properties of polymers, so the high -temperature-resistance of polyethylene (PE) was increased by irradiation. The national products of High -density-polyethylene (HDPE), crosslinking promoters, flame-retardant, antioxidants, Si rubber, and Ethylene-propylene-monomer (EPDM) were used as cable insulation. After -irradiation, thermal-endurance can get above 135, and high flame retardance was firmed, Oxygen index can get above 32 by crosslinking

  8. Intermetallic and electrical insulator coatings on high-temperature alloys in liquid-lithium environments

    International Nuclear Information System (INIS)

    Park, J.H.

    1994-06-01

    In the design of liquid-metal cooling systems for fusion-reactor blanket, applications, the corrosion resistance of structural materials and the magnetohydrodynamic (MHD) force and its subsequent influence on thermal hydraulics and corrosion are major concerns. When the system is cooled by liquid metals, insulator coatings are required on piping surfaces in contact with the coolant. The objective of this study is to develop stable corrosion-resistant electrical insulator coatings at the liquid-metal/structural-material interface, with emphasis on electrically insulating coatings that prevent adverse MHD-generated currents from passing through the structural wall, and Be-V intermetallic coatings for first-wall components that face the plasma. Vanadium and V-base alloys are leading candidate materials for structural applications in a fusion reactor. Various intermetallic films were produced on V-alloys and on Types 304 and 316 stainless steel. The intermetallic layers were developed by exposure of the materials to liquid Li containing 2 at temperatures of 500--1030 degree C. CaO electrical insulator coatings were produced by reaction of the oxygen-rich layer with <5 at. % Ca dissolved in liquid Li at 400--700 degree C. The reaction converted the oxygen-rich layer to an electrically insulating film. This coating method is applicable to reactor components because the liquid metal can be used over and over; only the solute within the liquid metal is consumed. This paper will discuss initial results on the nature of the coatings and their in-situ electrical resistivity characteristics in liquid Li at high temperatures

  9. Improved thermal monitoring of rotating machine insulation

    International Nuclear Information System (INIS)

    Stone, G.C.; Sedding, H.G.; Bernstein, B.S.

    1991-01-01

    Aging of motor and generator insulation is most often induced as a result of operation at high temperatures. In spite of this knowledge, stator and rotor temperatures are only crudely monitored in existing machines. In EPRI project RP2577-1, three new means of detecting machine temperatures were successfully developed. Two of the techniques, the Electronic Rotor Temperature Sensor and the Passive Rotor Temperature Sensor, were specifically developed to give point temperature readings on turbine generator rotor windings. The Insulation Sniffer allows operators to determine when any electrical insulation in a motor is overheating. Another electronic device, called the Thermal Life Indicator, helps operators and maintenance personnel determine how accumulated operation has affected the remaining life of the insulation in rotating machines. These new devices permit nuclear station operators to avoid hazardous operating conditions and will help to determine priorities for maintenance and plant life extension programs

  10. High Temperature Fiberoptic Thermal Imaging System, Phase I

    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...

  11. Lightweight, Thermally Insulating Structural Panels

    Science.gov (United States)

    Eisen, Howard J.; Hickey, Gregory; Wen, Liang-Chi; Layman, William E.; Rainen, Richard A.; Birur, Gajanana C.

    1996-01-01

    Lightweight, thermally insulating panels that also serve as structural members developed. Honeycomb-core panel filled with low-thermal-conductivity, opacified silica aerogel preventing convection and minimizes internal radiation. Copper coating on face sheets reduces radiation. Overall thermal conductivities of panels smaller than state-of-art commercial non-structurally-supporting foam and fibrous insulations. On Earth, panels suitable for use in low-air-pressure environments in which lightweight, compact, structurally supporting insulation needed; for example, aboard high-altitude aircraft or in partially evacuated panels in refrigerators.

  12. Heat insulating structure for use in transporting and handling gas of high temperature and pressure

    International Nuclear Information System (INIS)

    Mathusima, T.; Sato, T.; Uenishi, A.

    1980-01-01

    A heat insulating structure is described that has a heat-resistant tube disposed in a tubular cylindrical body and defining a passage for a high temperature gas, a heat insulating material disposed between the tube and the tubular cylindrical body and adapted to prevent the heat possessed by the gas from being transmitted to the tubular cylindrical body, and a spring adapted to bias the heat insulating material toward the inner surface of the tubular cylindrical body, so as to prevent the formation of a bypass passage for the gas including the gap between the tubular cylindrical body and the heat insulating material. The heat insulating material consists of a plurality of fibrous heat insulating materials mainly consisting of bulky fibrous materials and a plurality of shaped fibrous heat insulating materials. These fibrous heat insulating materials and the shaped fibrous heat insulating materials are arranged alternatingly and independently in the axial direction. In each of the bulky fibrous heat insulating material, disposed is a spring for biasing the shaped fibrous heat insulating material in the axial direction

  13. Thermal performances of an insulating structure for a reactor vessel

    International Nuclear Information System (INIS)

    Aranovitch, E.; Crutzen, S.; Le Det, M.; Denis, R.

    1974-12-01

    This report describes the thermal and technological tests performed on a multilayer thermal insulation system for high temperature gas reactors. It includes the description of test facilities, global tests, interpretation of data, and technological tests. Results obtained make it possible to predetermine with a satisfactory precision thermal performances under various nominal conditions

  14. Investigation of deterioration mechanism of electrical ceramic insulating materials under high temperature

    International Nuclear Information System (INIS)

    Mizutani, Yoshinobu; Ito, Tetsuo; Okamoto, Tatsuki; Kumazawa, Ryoji; Aizawa, Rie; Moriyama, Hideshige

    2000-01-01

    It is thought that ceramic insulator can be applied to electric power equipments that are under high temperature not to be able use organic materials. Our research has suggested components of mica-alumina combined insulation. As the results of and carried out temperature accelerating test, combined insulation life is expected long term over 40 years at over 500-Celsius degrees. However to construct high reliable insulating system, it is clarified deterioration mechanism on combined insulation and evaluates life of that. Therefore we carried out metal behavior test and voltage aging test using mica-sheet and alumina-cloth that are components of combined insulation under high temperature in nitrogen gas atmosphere. It is cleared two metal behavior mechanisms: One is that the opening of insulator are filled up with copper that is oxidized, the other is the metal diffuses in alumina-cloth through surface. And distance of metal behavior is able to be estimated at modulate temperature and in modulate time. It is also cleared that alumina-cloth is deteriorated by metal behavior into alumina-cloth. These results indicate that combined insulation is deteriorated from electrode side by metal behavior and is finally broken down through alumina-cloth. (author)

  15. High temperature study of flexible silicon-on-insulator fin field-effect transistors

    KAUST Repository

    Diab, Amer El Hajj

    2014-09-29

    We report high temperature electrical transport characteristics of a flexible version of the semiconductor industry\\'s most advanced architecture: fin field-effect transistor on silicon-on-insulator with sub-20 nm fins and high-κ/metal gate stacks. Characterization from room to high temperature (150 °C) was completed to determine temperature dependence of drain current (Ids), gate leakage current (Igs), transconductance (gm), and extracted low-field mobility (μ0). Mobility degradation with temperature is mainly caused by phonon scattering. The other device characteristics show insignificant difference at high temperature which proves the suitability of inorganic flexible electronics with advanced device architecture.

  16. 5th Duisburg thermal insulation days. Fuenfte Duisburger Waermedaemm-Tage

    Energy Technology Data Exchange (ETDEWEB)

    Agst, J. (ed.)

    1989-01-01

    This volume contains 18 specialist lectures mainly about the problems of thermal insulation in industrial furnaces and facility engineering. Among the subjects are: formed parts, monolithic lining materials and fillers of vermiculite; pyro-block-modular systems for furnaces (of the company DYKO-Morgan Fasertechnik); microporous insulating materials (KAOWOOL); properties of lightweight refractory bricks; thermal insulation in induction furnaces; vacuum moulded parts in electric furnace engineering; high temperature insulating materials with ceramic fibres; microtherm insulating materials. (MM).

  17. Thermal Protective Coating for High Temperature Polymer Composites

    Science.gov (United States)

    Barron, Andrew R.

    1999-01-01

    The central theme of this research is the application of carboxylate-alumoxane nanoparticles as precursors to thermally protective coatings for high temperature polymer composites. In addition, we will investigate the application of carboxylate-alumoxane nanoparticle as a component to polymer composites. The objective of this research was the high temperature protection of polymer composites via novel chemistry. The significance of this research is the development of a low cost and highly flexible synthetic methodology, with a compatible processing technique, for the fabrication of high temperature polymer composites. We proposed to accomplish this broad goal through the use of a class of ceramic precursor material, alumoxanes. Alumoxanes are nano-particles with a boehmite-like structure and an organic periphery. The technical goals of this program are to prepare and evaluate water soluble carboxylate-alumoxane for the preparation of ceramic coatings on polymer substrates. Our proposed approach is attractive since proof of concept has been demonstrated under the NRA 96-LeRC-1 Technology for Advanced High Temperature Gas Turbine Engines, HITEMP Program. For example, carbon and Kevlar(tm) fibers and matting have been successfully coated with ceramic thermally protective layers.

  18. High temperature solar thermal technology: The North Africa Market

    Energy Technology Data Exchange (ETDEWEB)

    1990-12-01

    High temperature solar thermal (HTST) technology offers an attractive option for both industrialized and non-industrialized countries to generate electricity and industrial process steam. The purpose of this report is to assess the potential market for solar thermal applications in the North African countries of Algeria, Egypt, Morocco and Tunisia. North Africa was selected because of its outstanding solar resource base and the variety of applications to be found there. Diminishing oil and gas resources, coupled with expanding energy needs, opens a large potential market for the US industry. The US high temperature solar trough industry has little competition globally and could build a large market in these areas. The US is already familiar with certain solar markets in North Africa due to the supplying of substantial quantities of US-manufactured flat plate collectors to this region.

  19. Thermal insulation of fuel elements

    International Nuclear Information System (INIS)

    Dubrovcak, P.; Pec, V.; Pitonak, J.

    1978-01-01

    The claim of the invention concerns thermal insulation of fuel elements heated for measurement of uranium fuel physical properties. For this, layers of aluminium film and of glass fibre are wound onto the inner tube of the element cladding. The space between the inner and the outer tubes is evacuated and the tubes are spaced using spacer wires. (M.S.)

  20. High temperature underground thermal energy storage system for solar energy

    Science.gov (United States)

    Collins, R. E.

    1980-01-01

    The activities feasibility of high temperature underground thermal storage of energy was investigated. Results indicate that salt cavern storage of hot oil is both technically and economically feasible as a method of storing huge quantities of heat at relatively low cost. One particular system identified utilizes a gravel filled cavern leached within a salt dome. Thermal losses are shown to be less than one percent of cyclically transferred heat. A system like this having a 40 MW sub t transfer rate capability and over eight hours of storage capacity is shown to cost about $13.50 per KWh sub t.

  1. Practical reasons for investigating ion transport in high temperature insulating materials

    International Nuclear Information System (INIS)

    Sonder, E.

    1976-01-01

    Practical problems encountered in a number of advanced technology appliations, particularly those related to energy conversion, are discussed. Refractory ionic compounds which are abundant and of high melting point are listed, and technological problems are discussed in terms of specific materials problems. The argument is made that basic information concerning transport properties in refractory compounds is lacking to such an extent that it is difficult to design and assess advanced energy generation systems. Technology applications include: a) ceramic nuclear fuels for high temperature fission reactors, b) high temperature gas turbine blades, c) insulators in controlled thermonuclear reactors, and d) magnetohydrodynamic generators. Some of the difficulties inherent in making transport property measurements at high temperatures are also listed

  2. 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.

  3. Generation, insulated confinement, and heating of ultra-high temperature plasmas

    International Nuclear Information System (INIS)

    Bass, R.W.

    1986-01-01

    This invention relates to the production and maintenance in steady state of ultra-high temperature confined plasmas, particularly those created by full ionization of a volume of some hydrogenic gas such as deuterium. The target mass is surrounded with an ambient fluid medium at a predetermined pressure. Pulsed energy is projected upon the target mass to bring it to a predetermined temperature and to fully ionize it; this energy may be pulsed photon energy or pulsed particle-beam kinetic energy. An electrostatic double layer is formed spontaneously between the ionized mass and the ambient medium, providing thermal insulation and leaving the dominant energy loss to be bremmstrahlung losses. The bremmstrahlung losses are compensated for completely by supplying additional radiant energy to the ionized mass to maintain its temperature. The frequency range of the additional radiant energy is selected so as to be absorbable by the ionized mass, and its power level is adjusted to maintain the ionized mass in a substantially steady state. The static pressure of the ambient medium is increased, thereby equally increasing the static pressure of the ionized mass so as to enable the mass to absorb more of the radiant energy and increasing its temperature but also increasing its power losses. Simultaneously the radius and temperature of the mass are monitored and the power level of the radiant energy supply is increased to as to compensate for the power losses. The minimum feasible size of the plasma is less than a centimeter in diameter, while there is no constraint on maximum feasible size. This invention may be practiced with commercially-available lasers and microwave beam generators

  4. Positron annihilation in germanium in thermal equilibrium at high temperature

    Energy Technology Data Exchange (ETDEWEB)

    Uedono, Akira; Moriya, Tsuyoshi; Komuro, Naoyuki; Tanigawa, Shoichiro [Tsukuba Univ., Ibaraki (Japan). Inst. of Materials Science; Kawano, Takao; Ikari, Atsushi

    1996-09-01

    Annihilation characteristics of positrons in Ge in thermal equilibrium at high temperature were studied using a monoenergetic positron beam. Precise measurements of Doppler broadening profiles of annihilation radiation were performed in the temperature range between 300 K and 1211 K. The line shape parameters of Doppler broadening profiles were found to be almost constant at 300-600 K. The changes in these parameters were observed to start above 600 K. This was attributed to both the decrease in the fraction of positrons annihilating with core electrons and the lowering of the crystal symmetry around the region detected by positron-electron pairs. This suggests that behaviors of positrons are dominated by some form of positron-lattice coupling in Ge at high temperatures. The temperature dependence of the diffusion length of positrons was also discussed. (author)

  5. Passive Collecting of Solar Radiation Energy using Transparent Thermal Insulators, Energetic Efficiency of Transparent Thermal Insulators

    Directory of Open Access Journals (Sweden)

    Smajo Sulejmanovic

    2014-11-01

    Full Text Available This paper explains passive collection of solar radiation energy using transparent thermal insulators. Transparent thermal insulators are transparent for sunlight, at the same time those are very good thermal insulators. Transparent thermal insulators can be placed instead of standard conventional thermal insulators and additionally transparent insulators can capture solar radiation, transform it into heat and save heat just as standard insulators. Using transparent insulators would lead to reduce in usage of fossil fuels and would help protection of an environment and reduce effects of global warming, etc.

  6. Thermal-Insulation Properties of Multilayer Textile Packages

    Directory of Open Access Journals (Sweden)

    Matusiak Małgorzata

    2014-12-01

    Full Text Available Thermal-insulation properties of textile materials play a significant role in material engineering of protective clothing. Thermal-insulation properties are very important from the point of view of thermal comfort of the clothing user as well as the protective efficiency against low or high temperature. Thermal protective clothing usually is a multilayer construction. Its thermal insulation is a resultant of a number of layers and their order, as well as the thermalinsulation properties of a single textile material creating particular layers. The aim of the presented work was to investigate the relationships between the thermal-insulation properties of single materials and multilayer textile packages composed of these materials. Measurement of the thermal-insulation properties of single and multilayer textile materials has been performed with the Alambeta. The following properties have been investigated: thermal conductivity, resistance and absorptivity. Investigated textile packages were composed of two, three and four layers made of woven and knitted fabrics, as well as nonwovens. On the basis of the obtained results an analysis has been carried out in order to assess the dependency of the resultant values of the thermal-insulation properties of multilayer packages on the appropriate values of particular components.

  7. Fiber Bragg Gratings for High-Temperature Thermal Characterization

    International Nuclear Information System (INIS)

    Stinson-Bagby, Kelly L.; Fielder, Robert S.

    2004-01-01

    Fiber Bragg grating (FBG) sensors were used as a characterization tool to study the SAFE-100 thermal simulator at the Nasa Marshal Space Flight Center. The motivation for this work was to support Nasa space nuclear power initiatives through the development of advanced fiber optic sensors for space-based nuclear power applications. Distributed high temperature measurements, up to 1150 deg. C, were made with FBG temperature sensors. Additionally, FBG strain measurements were taken at elevated temperatures to provide a strain profile of the core during operation. This paper will discuss the contribution of these measurements to meet the goals of Nasa Marshall Space Flight Center's Propulsion Research Center. (authors)

  8. Thermal analysis of high temperature phase transformations of steel

    Directory of Open Access Journals (Sweden)

    K. Gryc

    2013-10-01

    Full Text Available The series of thermal analysis measurements of high temperature phase transformations of real grain oriented electrical steel grade under conditions of two analytical devices (Netzsch STA 449 F3 Jupiter; Setaram SETSYS 18TM were carried out. Two thermo analytical methods were used (DTA and Direct thermal analysis. The different weight of samples was used (200 mg, 23 g. The stability/reproducibility of results obtained by used methodologies was verified. The liquidus and solidus temperatures for close to equilibrium conditions and during cooling (20 °C/min; 80 °C/min were determined. It has been shown that the higher cooling rate lead to lower temperatures for start and end of solidification process of studied steel grade.

  9. Exploration of porous SiC nanostructures as thermal insulator with high thermal stability and low thermal conductivity

    Institute of Scientific and Technical Information of China (English)

    Peng; WAN; Jingyang; WANG

    2016-01-01

    The crucial challenge for current nanoscale thermal insulation materials,such as Al2O3 and SiO2 aerogel composites,is to solve the trade-off between extremely low thermal conductivity and unsatisfied thermal stability.Typical high-temperature ceramic SiC possesses excellent mechanical properties and

  10. Thermal insulation properties of walls

    Directory of Open Access Journals (Sweden)

    Zhukov Aleksey Dmitrievich

    2014-05-01

    Full Text Available Heat-protective qualities of building structures are determined by the qualities of the used materials, adequate design solutions and construction and installation work of high quality. This rule refers both to the structures made of materials similar in their structure and nature and mixed, combined by a construction system. The necessity to ecaluate thermal conductivity is important for a product and for a construction. Methods for evaluating the thermal protection of walls are based on the methods of calculation, on full-scale tests in a laboratory or on objects. At the same time there is a reason to believe that even deep and detailed calculation may cause deviation of the values from real data. Using finite difference method can improve accuracy of the results, but it doesn’t solve all problems. The article discusses new approaches to evaluating thermal insulation properties of walls. The authors propose technique of accurate measurement of thermal insulation properties in single blocks and fragments of walls and structures.

  11. Lifetime improvement of sheathed thermocouples for use in high-temperature and thermal transient operations

    International Nuclear Information System (INIS)

    McCulloch, R.W.; Clift, J.H.

    1982-01-01

    Premature failure of small-diameter, magnesium-oxide-insulated sheathed thermocouples occurred when they were placed within nuclear fuel rod simulators (FRSs) to measure high temperatures and to follow severe thermal transients encountered during simulation of nuclear reactor accidents in Oak Ridge National Laboratory (ORNL) thermal-hydraulic test facilities. Investigation of thermally cycled thermocouples yielded three criteria for improvement of thermocouple lifetime: (1) reduction of oxygen impurities prior to and during their fabrication, (2) refinement of thermoelement grain size during their fabrication, and (3) elimination of prestrain prior to use above their recrystallization temperature. The first and third criteria were satisfied by improved techniques of thermocouple assembly and by a recovery anneal prior to thermocouple use

  12. High-temperature turbopump assembly for space nuclear thermal propulsion

    Science.gov (United States)

    Overholt, David M.

    1993-01-01

    The development of a practical, high-performance nuclear rocket by the U.S. Air Force Space Nuclear Thermal Propulsion (SNTP) program places high priority on maximizing specific impulse (ISP) and thrust-to-weight ratio. The operating parameters arising from these goals drive the propellant-pump design. The liquid hydrogen propellant is pressurized and pumped to the reactor inlet by the turbopump assembly (TPA). Rocket propulsion is effected by rapid heating of the propellant from 100 K to thousands of degrees in the particle-bed reactor (PBR). The exhausted propellant is then expanded through a high-temperature nozzle. One approach to achieve high performance is to use an uncooled carbon-carbon nozzle and duct turbine inlet. The high-temperature capability is obtained by using carbon-carbon throughout the TPA hot section. Carbon-carbon components in development include structural parts, turbine nozzles/stators, and turbine rotors. The technology spinoff is applicable to conventional liquid propulsion engines plus a wide variety of other turbomachinery applications.

  13. High-temperature turbopump assembly for space nuclear thermal propulsion

    International Nuclear Information System (INIS)

    Overholt, D.M.

    1993-01-01

    The development of a practical, high-performance nuclear rocket by the U.S. Air Force Space Nuclear Thermal Propulsion (SNTP) program places high priority on maximizing specific impulse (ISP) and thrust-to-weight ratio. The operating parameters arising from these goals drive the propellant-pump design. The liquid hydrogen propellant is pressurized and pumped to the reactor inlet by the turbopump assembly (TPA). Rocket propulsion is effected by rapid heating of the propellant from 100 K to thousands of degrees in the particle-bed reactor (PBR). The exhausted propellant is then expanded through a high-temperature nozzle. One approach to achieve high performance is to use an uncooled carbon-carbon nozzle and duct turbine inlet. The high-temperature capability is obtained by using carbon-carbon throughout the TPA hot section. Carbon-carbon components in development include structural parts, turbine nozzles/stators, and turbine rotors. The technology spinoff is applicable to conventional liquid propulsion engines plus a wide variety of other turbomachinery applications

  14. High temperature ductility of austenitic alloys exposed to thermal neutrons

    International Nuclear Information System (INIS)

    Watanabe, K.; Kondo, T.; Ogawa, Y.

    1982-01-01

    Loss of high temperature ductility due to thermal neutron irradiation was examined by slow strain rate test in vacuum up to 1000 0 C. The results on two heats of Hastelloy alloy X with different boron contents were analyzed with respect to the influence of the temperatures of irradiation and tensile tests, neutron fluence and the associated helium production due to nuclear transmutation reaction. The loss of ductility was enhanced by increasing either temperature or neutron fluence. Simple extrapolations yielded the estimated threshold fluence and the end-of-life ductility values at 900 and 1000 0 C in case where the materials were used in near-core regions of VHTR. The observed relationship between Ni content and the ductility loss has suggested a potential utilization of Fe-based alloys for seathing of the neutron absorber materials

  15. Fabrication of High Temperature Cermet Materials for Nuclear Thermal Propulsion

    Science.gov (United States)

    Hickman, Robert; Panda, Binayak; Shah, Sandeep

    2005-01-01

    Processing techniques are being developed to fabricate refractory metal and ceramic cermet materials for Nuclear Thermal Propulsion (NTP). Significant advances have been made in the area of high-temperature cermet fuel processing since RoverNERVA. Cermet materials offer several advantages such as retention of fission products and fuels, thermal shock resistance, hydrogen compatibility, high conductivity, and high strength. Recent NASA h d e d research has demonstrated the net shape fabrication of W-Re-HfC and other refractory metal and ceramic components that are similar to UN/W-Re cermet fuels. This effort is focused on basic research and characterization to identify the most promising compositions and processing techniques. A particular emphasis is being placed on low cost processes to fabricate near net shape parts of practical size. Several processing methods including Vacuum Plasma Spray (VPS) and conventional PM processes are being evaluated to fabricate material property samples and components. Surrogate W-Re/ZrN cermet fuel materials are being used to develop processing techniques for both coated and uncoated ceramic particles. After process optimization, depleted uranium-based cermets will be fabricated and tested to evaluate mechanical, thermal, and hot H2 erosion properties. This paper provides details on the current results of the project.

  16. High-Temperature Thermal Diffusivity Measurements of Silicate Glasses

    Science.gov (United States)

    Pertermann, M.; Hofmeister, A. M.; Whittington, A. G.; Spera, F. J.; Zayac, J.

    2005-12-01

    Transport of heat in geologically relevant materials is of great interest because of its key role in heat transport, magmatism and volcanic activity on Earth. To better understand the thermal properties of magmatic materials at high temperatures, we measured the thermal diffusivity of four synthetic end-member silicate glasses with the following compositions: albite (NaAlSi3O8), orthoclase (KAlSi3O8), anorthite (CaAl2Si2O8), and diopside (CaMgSi2O6). Thermal diffusivity measurements were conducted with the laser-flash technique and data were acquired from room temperature to a maximum temperature near 1100°C, depending on the glass transition temperature. The presence of sub-mm sized bubbles in one of the orthoclase samples had no discernable effect on measured diffusivities. At room temperature, the three feldspar-type glasses have thermal diffusivity (D) values of 0.58-0.61 mm2/s, whereas the diopside glass has 0.52 mm2/s. With increasing temperature, D decreases by 5-10% (relative) for all samples and becomes virtually constant at intermediate temperatures. At higher temperatures, the anorthite and diopside glasses exhibit significant drops in thermal diffusivity over a 50-100°C interval, correlating with previously published heat capacity changes near the glass transition for these compositions. For anorthite, D (in mm2/s) decreases from 0.48 at 750-860°C to 0.36 at 975-1075°C; for diopside, D changes from 0.42 at 630-750°C to 0.30 at 850-910°C, corresponding to relative drops of 24 and 29%, respectively. Albite and orthoclase glasses do not exhibit this change and also lack significant changes in heat capacity near the glass transition. Instead, D is constant at 400-800°C for albite, and for orthoclase values go through a minimum at 500-600°C before increasing slightly towards 1100°C but it never exceeds the room temperature D. Our data on thermal diffusivity correlate closely with other thermophysical properties. Thus, at least in case of simple

  17. Research on thermal insulation for hot gas ducts

    International Nuclear Information System (INIS)

    Broeckerhoff, P.

    1984-01-01

    The inner surfaces of prestressed reactor vessels and hot gas ducts of Gas Cooled High Temperature Reactors need internal thermal insulation to protect the pressure bearing walls from high temperatures. The design parameters of the insulation depend on the reactor type. In a PNP-plant temperature and pressure of the cooling medium helium are proposed to be 950 deg. C and 40 bars, respectively. The experimental work was started at KFA in 1971 for the HHT-project using three test facilities. At first metallic foil insulation and stuffed fibre insulating systems, the hot gas ducting shrouds of which were made of metal, have been tested. Because of the elevated helium temperature in case of PNP and the resulting lower strength of the metallic parts the interest was directed to rigid ceramic materials for the spacers and the inner shrouds. This led to modified structures designed by the INTERATOM company. Tests were performed at KFA. The main object of the investigations was to study the influence of temperature, pressure and axial pressure gradients on the thermal efficiency of the structures. Moreover, the temperatures within the insulation, at the pressure tube, and at the elements which bear the inner shrouds were measured. Thermal fluxes and effective thermal conductivities in axial and circumferential direction of the pressure tube are given, mainly for the INTERATOM-design with spherical spacers. (author)

  18. Ultra high-temperature solids-free insulating packer fluid for oil and gas production, steam injection and geothermal wells

    Energy Technology Data Exchange (ETDEWEB)

    Ezell, R.G.; Harrison, D.J. [Society of Petroleum Engineers, Canadian Section, Calgary, AB (Canada)]|[Halliburton Energy Services, Calgary, AB (Canada)

    2008-10-15

    Uncontrolled heat transfer from production/injection tubing during thermal oil recovery via steam injection can be detrimental to the integrity of the casing and to the quality of the steam that is injected into the reservoir. An aqueous-based insulating packer fluid (IPF) was introduced to improve the steam injection process by controlling the total heat loss from the produced fluids to the surrounding wellbore, internal annuli and formation. The IPF was developed for elevated temperature environments through extensive investigation across multidisciplinary technology. The innovative system delivers performance beyond conventional systems of comparable thermal conductivity. Its density range and conductivity measurements were presented in this paper. High-temperature static aging tests showed superior gel integrity without any phase separation after exposure to temperatures higher than 260 degrees C. The new fluids are hydrate inhibitive, non-corrosive and pass oil and grease testing. They are considered to be environmentally sound by Gulf of Mexico standards. It was concluded that the new ultra high-performance insulating packer fluid (HTIPF) reduced the heat loss significantly by both conduction and convection. Heat transfer within the aqueous-based HTIPF was 97 per cent less than that of pure water. It was concluded that the HTIPF can be substituted for conventional packer fluids without compromising any well control issues. 21 refs., 1 tab., 4 figs.

  19. Handleable shapes of thermal insulation material

    Energy Technology Data Exchange (ETDEWEB)

    Hughes, J. T.

    1989-01-17

    Handleable and machineable shapes of thermal insulation material are made by compacting finely divided thermal insulation material into the cells of a reinforcing honeycomb insulation material into the cells of a reinforcing honeycomb structure. The finely divided thermal insulation material may be, for example, silica aerogel, pyrogenic silica, carbon black, silica gel, volatilised silica, calcium silicate, vermiculate or perlite, or finely divided metal oxides such as alumina or titania. The finely divided thermal insulation material may include an infra-red opacifier and/or reinforcing fibres. The reinforcing honeycomb structure may be made from, for example, metals such as aluminium foil, inorganic materials such as ceramics, organic materials such as plastics materials, woven fabrics or paper. A rigidiser may be employed. The shapes of thermal insulation material are substantially rigid and may be machines, for example by mechanical or laser cutting devices, or may be formed, for example by rolling, into curved or other shaped materials. 12 figs.

  20. No-insulation multi-width winding technique for high temperature superconducting magnet.

    Science.gov (United States)

    Hahn, Seungyong; Kim, Youngjae; Keun Park, Dong; Kim, Kwangmin; Voccio, John P; Bascuñán, Juan; Iwasa, Yukikazu

    2013-10-21

    We present a No-Insulation ( NI ) Multi-Width ( MW ) winding technique for an HTS (high temperature superconductor) magnet consisting of double-pancake (DP) coils. The NI enables an HTS magnet self-protecting and the MW minimizes the detrimental anisotropy in current-carrying capacity of HTS tape by assigning tapes of multiple widths to DP coils within a stack, widest tape to the top and bottom sections and the narrowest in the midplane section. This paper presents fabrication and test results of an NI-MW HTS magnet and demonstrates the unique features of the NI-MW technique: self-protecting and enhanced field performance, unattainable with the conventional technique.

  1. Quantitative analysis of thermal insulation coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2014-01-01

    This work concerns the development of simulation tools for mapping of insulation properties of thermal insulation coatings based on selected functional filler materials. A mathematical model, which includes the underlying physics (i.e. thermal conductivity of a heterogeneous two-component coating...

  2. Study of thermal conductivity of multilayer insulation

    Energy Technology Data Exchange (ETDEWEB)

    Dutta, D; Sundaram, S; Nath, G K; Sethuram, N P; Chandrasekharan, T; Varadarajan, T G [Heavy Water Division, Bhabha Atomic Research Centre, Mumbai (India)

    1994-06-01

    This paper presents experimental determination of the apparent thermal conductivity of multilayer insulation for a cryogenic system. The variation of thermal conductivity with residual gas pressure is studied and the optimum vacuum for good insulating performance is determined. Evaporation loss technique for heat-inleak determination is employed. (author). 3 refs., 3 figs.

  3. Study of thermal conductivity of multilayer insulation

    International Nuclear Information System (INIS)

    Dutta, D.; Sundaram, S.; Nath, G.K.; Sethuram, N.P.; Chandrasekharan, T.; Varadarajan, T.G.

    1994-01-01

    This paper presents experimental determination of the apparent thermal conductivity of multilayer insulation for a cryogenic system. The variation of thermal conductivity with residual gas pressure is studied and the optimum vacuum for good insulating performance is determined. Evaporation loss technique for heat-inleak determination is employed. (author)

  4. Thermal hydraulics analysis of the Advanced High Temperature Reactor

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Dean, E-mail: Dean_Wang@uml.edu [University of Massachusetts Lowell, One University Avenue, Lowell, MA 01854 (United States); Yoder, Graydon L.; Pointer, David W.; Holcomb, David E. [Oak Ridge National Laboratory, 1 Bethel Valley RD #6167, Oak Ridge, TN 37831 (United States)

    2015-12-01

    Highlights: • The TRACE AHTR model was developed and used to define and size the DRACS and the PHX. • A LOFF transient was simulated to evaluate the reactor performance during the transient. • Some recommendations for modifying FHR reactor system component designs are discussed. - Abstract: The Advanced High Temperature Reactor (AHTR) is a liquid salt-cooled nuclear reactor design concept, featuring low-pressure molten fluoride salt coolant, a carbon composite fuel form with embedded coated particle fuel, passively triggered negative reactivity insertion mechanisms, and fully passive decay heat rejection. This paper describes an AHTR system model developed using the Nuclear Regulatory Commission (NRC) thermal hydraulic transient code TRAC/RELAP Advanced Computational Engine (TRACE). The TRACE model includes all of the primary components: the core, downcomer, hot legs, cold legs, pumps, direct reactor auxiliary cooling system (DRACS), the primary heat exchangers (PHXs), etc. The TRACE model was used to help define and size systems such as the DRACS and the PHX. A loss of flow transient was also simulated to evaluate the performance of the reactor during an anticipated transient event. Some initial recommendations for modifying system component designs are also discussed. The TRACE model will be used as the basis for developing more detailed designs and ultimately will be used to perform transient safety analysis for the reactor.

  5. Method of manufacturing a thermally insulating body

    Energy Technology Data Exchange (ETDEWEB)

    McWilliams, J.A.; Morgan, D.E.; Jackson, J.D.

    1988-10-11

    A method of manufacturing a microporous thermally insulating body comprises mixing together a finely divided microporous insulating material such as silica aerogel or pyrogenic silica and a solid ammonia-generating compound in particulate form, and compressing the mixture to form a thermally insulating body. The ammonia-generating compound is dispersed evenly throughout the insulating material and may comprise, for example, ammonium carbonate, ammonium acetate or urea. Preferably, the ammonia-generating compound comprises a mixture of about one third by weight of ammonium carbonate and about two thirds by weight of ammonium bicarbonate together with a small proportion of magnesium oxide. Experiments are described which illustrate the manufacturing process. 6 tabs.

  6. Thermal-mechanical fatigue of high temperature structural materials

    Science.gov (United States)

    Renauld, Mark Leo

    Experimental and analytical methods were developed to address the effect of thermal-mechanical strain cycling on high temperature structural materials under uniaxial and biaxial stress states. Two materials were used in the investigation, a nickel-base superalloy of low ductility, IN-738LC and a high ductility material, 316 stainless steel. A uniaxial life prediction model for the IN-738LC material was based on tensile hysteresis energy measured in stabilized, mid-life hysteresis loops. Hold-time effects and temperature cycling were incorporated in the hysteresis energy approach. Crack growth analysis was also included in the model to predict the number of TMF cycles to initiate and grow a fatigue crack through the coating. The nickel-base superalloy, IN-738LC, was primarily tested in out-of-phase (OP) TMF with a temperature range from 482-871sp°C (900-1600sp°F) under continuous and compressive hold-time cycling. IN-738LC fatigue specimens were coated either with an aluminide, NiCoCrAlHfSi overlay or CoNiCrAlY overlay coating on the outer surface of the specimen. Metallurgical failure analysis via optical and scanning electron microscopy, was used to characterize failure behavior of both substrate and coating materials. Type 316 SS was subjected to continuous biaxial strain cycling with an in-phase (IP) TMF loading and a temperature range from 399-621sp°C (750-1150sp°F). As a result, a biaxial TMF life prediction model was proposed on the basis of an extended isothermal fatigue model. The model incorporates a frequency effect and phase factors to assess the different damage mechanisms observed during TMF loading. The model was also applied to biaxial TMF data generated on uncoated IN-738LC.

  7. Tensile toughness test and high temperature fracture analysis of thermal barrier coatings

    International Nuclear Information System (INIS)

    Qian, G.; Nakamura, T.; Berndt, C.C.; Leigh, S.H.

    1997-01-01

    In this paper, an effective fracture toughness test which uses interface fracture mechanics theory is introduced. This method is ideally suited for determining fracture resistance of multilayered thermal barrier coatings (TBCs) consisting of ceramic and bond layers and, unlike other fracture experiments, requires minimal set-up over a simple tensile adhesion test. Furthermore, while other test methods usually use edge cracked specimens, the present test models a crack embedded within the coatings, which is more consistent with actual TBCs where failure initiates from internal voids or defects. The results of combined computational and experimental analysis show that any defects located within the ceramic coating can significantly weaken a TBC, whereas the debonding resistances of the bond coating and its interfaces are found to be much higher. In a separate analysis, the authors have studied fracture behavior of TBCs subjected to thermal loading in a high temperature environment. The computed fracture parameters reveal that when the embedded crack size is on order of the coating thickness, the fracture driving force is comparable to the fracture resistance of the coating found in the toughness test. In addition, the major driving force for fracture derives from the thermal insulating effect across the crack faces rather than the mismatch in the coefficients of thermal expansion. The authors have also investigated the effects of functionally graded material (FGM) within TBCs and found its influences on the fracture parameters to be small. This result implies that the FGM may not contribute toward enhancing the fracture toughness of the TBCs considered here

  8. Energy conservation through thermally insulated structures

    International Nuclear Information System (INIS)

    Abu-Dayyeh, Ayoub

    2006-01-01

    The propose of this paper is to explicate its title through investigating the different available thermal insulating materials and the various techniques of application, as practiced in Jordan, in particular, and as practiced in many parts of the world in general, which will satisfy Jordanian standards in terms of heat transmittance and thermal comfort. A brief comparison with international standards will shed some light on the stringent measures enforced in the developed world and on our striving aspirations to keep pace. The paper consists of four main parts, pseudoally divided. The first part will deal with the mechanism of heat loss and heat gain in structures during summer and winter. It will also explain the Time-lag phenomenon which is vital for providing thermal comfort inside the dwellings. The second part will evaluate the damages induced by the temperature gradients on the different elements of the structure, particularly next to exterior opening. The paper will also demonstrate the damages induced by water condensation and fungus growth on the internal surfaces of the structure and within its skeleton. A correlation between condensation and thermal insulation will be established. The third part of the paper will evaluate the different available thermal insulating materials and the application techniques which will satisfy the needs for thermal insulating and thermal comfort at the least cost possible. The criteria of an economical design shall be established. As a conclusion, the paper infers answers to the following different criteria discussed throughout the different parts of the paper. The main theme of questions can be summarized as follows: 1)How energy conservation is possible due to thermal insulation? 2)The feasibility of investing in thermal insulation? 3)Is thermal comfort and a healthy atmosphere possible inside the dwellings during all season! What are the conditions necessary to sustain them? 4)What environmental impacts can exist due to

  9. A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university.

    Science.gov (United States)

    Choi, Y H; Song, J B; Yang, D G; Kim, Y G; Hahn, S; Lee, H G

    2016-10-01

    This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

  10. A novel no-insulation winding technique of high temperature-superconducting racetrack coil for rotating applications: A progress report in Korea university

    Science.gov (United States)

    Choi, Y. H.; Song, J. B.; Yang, D. G.; Kim, Y. G.; Hahn, S.; Lee, H. G.

    2016-10-01

    This paper presents our recent progress on core technology development for a megawatt-class superconducting wind turbine generator supported by the international collaborative R&D program of the Korea Institute of Energy Technology Evaluation and Planning. To outperform the current high-temperature-superconducting (HTS) magnet technology in the wind turbine industry, a novel no-insulation winding technique was first proposed to develop the second-generation HTS racetrack coil for rotating applications. Here, we briefly report our recent studies on no-insulation (NI) winding technique for GdBCO coated conductor racetrack coils in the following areas: (1) Charging-discharging characteristics of no-insulation GdBCO racetrack coils with respect to external pressures applied to straight sections; (2) thermal and electrical stabilities of no-insulation GdBCO racetrack coils encapsulated with various impregnating materials; (3) quench behaviors of no-insulation racetrack coils wound with GdBCO conductor possessing various lamination layers; (4) electromagnetic characteristics of no-insulation GdBCO racetrack coils under time-varying field conditions. Test results confirmed that this novel NI winding technique was highly promising. It could provide development of a compact, mechanically dense, and self-protecting GdBCO magnet for use in real-world superconducting wind turbine generators.

  11. Thermally assisted ordering in Mott insulators

    Science.gov (United States)

    Sims, Hunter; Pavarini, Eva; Koch, Erik

    2017-08-01

    Landau theory describes phase transitions as the competition between energy and entropy: The ordered phase has lower energy, while the disordered phase has larger entropy. When heating the system, ordering is reduced entropically until it vanishes at the critical temperature. This picture implicitly assumes that the energy difference between the ordered and disordered phases does not change with temperature. We show that for orbital ordering in the Mott insulator KCuF3, this assumption fails qualitatively: entropy plays a negligible role, while thermal expansion energetically stabilizes the orbitally ordered phase to such an extent that no phase transition is observed. To understand this strong dependence on the lattice constant, we need to take into account the Born-Mayer repulsion between the ions. It is the latter, and not the Jahn-Teller elastic energy, which determines the magnitude of the distortion. This effect will be seen in all materials where the distortion expected from the Jahn-Teller mechanism is so large that the ions would touch. Our mechanism explains not only the absence of a phase transition in KCuF3, but even suggests the possibility of an inverted transition in closed-shell systems, where the ordered phase emerges only at high temperatures.

  12. Thermal-hydraulic Analysis of High-temperature Cover Gas Region in STELLA-2

    Energy Technology Data Exchange (ETDEWEB)

    Jo, Youngchul; Son, Seok-Kwon; Yoon, Jung; Eoh, Jaehyuk; Jeong, Ji-Young [Korea Atomic Energy Research Institute, Daejeon (Korea, Republic of)

    2016-10-15

    The first phase of the program was focused on the key sodium component tests, and the second one has been concentrated on the sodium thermal-hydraulic integral effect test (STELLA-2). Based on its platform, simulation of the PGSFR transient will be made to evaluate plant dynamic behaviors as well as to demonstrate decay heat removal performance. Therefore, most design features of PGSFR have been modeled in STELLA-2 as closely as possible. The similarities of temperature and pressure between the model (STELLA-2) and the prototype (PGSFR) have been well preserved to reflect thermal-hydraulic behavior with natural convection as well as heat transfer between structure and sodium coolant inside the model reactor vessel (RV). For this reason, structural integrity of the entire test section should be confirmed as in the prototype. In particular, since the model reactor head in STELLA-2 supports key components and internal structures, its structural integrity exposed to high-temperature cover gas region should be confirmed. In order to reduce thermal radiation heat transfer from the hot sodium pool during normal operation, a dedicated insulation layer has been installed at the downward surface of the model reactor head to prevent direct heat flux from the sodium free surface at 545 .deg. C. Three-dimensional conjugate heat transfer analyses for the full-shape geometry of the upper part of the model reactor vessel in STELLA-2 have been carried out. Based on the results, steady-state temperature distributions in the cover gas region and the model reactor head itself have been obtained and the design requirement in temperature of the model reactor head has been newly proposed to be 350 .deg. C. For any elevated temperature conditions in STELLA-2, it was confirmed that the model reactor head generally satisfied the requirement. The CFD database constructed from this study will be used to optimize geometric parameters such as thicknesses and/or types of the insulator.

  13. Thermal characteristics of high-temperature R718 heat pumps with turbo compressor thermal vapor recompression

    International Nuclear Information System (INIS)

    Šarevski, Milan N.; Šarevski, Vasko N.

    2017-01-01

    Highlights: • High pressure ratio, high speed, transonic R718 centrifugal compressors. • High efficient industrial evaporators/concentrators with turbo thermal vapor recompression. • Utilization of waste heat from industrial thermal and processing systems. • R718 is an ideal refrigerant for the novel high-temperature industrial heat pumps. • Application of single-stage R718 centrifugal compressors. - Abstract: Characteristics of R718 centrifugal compressors are analyzed and range of their applications in industrial high-temperature heat pumps, district heating systems and geothermal green house heating systems are estimated. Implementation of turbo compressor thermal vapor recompression in industrial evaporating/concentrating plants for waste heat utilization results in a high energy efficiency and in other technical, economical and environmental benefits. A novel concept of turbo compression R718 heat pumps is proposed and an assessment of their thermal characteristics is presented for utilization of waste heat from industrial thermal plants and systems (boilers, furnaces, various technological and metallurgical cooling processes, etc.), and for applications in district heating and geothermal green house heating systems. R718 is an ideal refrigerant for the novel high-temperature turbo compression industrial heat pumps. Direct evaporation and condensation are advantages of the proposed system which lead to higher COP, and to simplification of the plant and lower cost.

  14. Gas cooled thermal reactors with high temperatures (VHTR)

    International Nuclear Information System (INIS)

    Bouchter, J.C.; Dufour, P.; Guidez, J.; Latge, C.; Renault, C.; Rimpault, G.; Vasile, A.

    2014-01-01

    VHTR is one of the 6 concepts retained for the 4. generation of nuclear reactors, it is an upgraded version of the HTR-type reactor (High Temperature Reactors). 5 HTR reactors were operated in the world in the eighties, now 2 experimental HTR are working in China and Japan and 2 HTR with an output power of 100 MWe are being built in China. The purpose of the VHTR is to provide an helium at very high temperatures around 1000 Celsius degrees that could be used directly in a thermochemical way to produce hydrogen for instance. HTR reactors are interesting in terms of safety but it does not optimise the consumption of uranium and the production of wastes. This article presents a brief historical account of HTR-type reactors and their main design and safety features. The possibility of using HTR to burn plutonium is also presented as well as the possibility of closing the fuel cycle and of using thorium-uranium fuel. (A.C.)

  15. High temperature glass thermal control structure and coating. [for application to spacecraft reusable heat shielding

    Science.gov (United States)

    Stewart, D. A.; Goldstein, H. E.; Leiser, D. B. (Inventor)

    1983-01-01

    A high temperature stable and solar radiation stable thermal control coating is described which is useful either as such, applied directly to a member to be protected, or applied as a coating on a re-usable surface insulation (RSI). It has a base coat layer and an overlay glass layer. The base coat layer has a high emittance, and the overlay layer is formed from discrete, but sintered together glass particles to give the overlay layer a high scattering coefficient. The resulting two-layer space and thermal control coating has an absorptivity-to-emissivity ratio of less than or equal to 0.4 at room temperature, with an emittance of 0.8 at 1200 F. It is capable of exposure to either solar radiation or temperatures as high as 2000 F without significant degradation. When used as a coating on a silica substrate to give an RSI structure, the coatings of this invention show significantly less reduction in emittance after long term convective heating and less residual strain than prior art coatings for RSI structures.

  16. High temperature thermal energy storage in moving sand

    Science.gov (United States)

    Turner, R. H.; Awaya, H. I.

    1978-01-01

    Several high-temperature (to 500 C) heat-storage systems using sand as the storage medium are described. The advantages of sand as a storage medium include low cost for sand, widespread availability, non-toxicity, non-degradation characteristics, easy containment, and safety. The systems considered include: stationary sand with closely spaced tubes throughout the volume, the use of a fluidized bed, use of conveyor belt transporter, and the use of a blower rapid transport system. For a stationary sand bed, very close spacing of heat transfer tubes throughout the volume is required, manifesting as high power related system cost. The suggestion of moving sand past or around pipes is intended to reduce the power related costs at the penalty of added system complexity. Preliminary system cost estimates are offered. These rough calculations indicate that mobile sand heat storage systems cost less than the stationary sand approach.

  17. High Temperature Thermal Properties of Bentonite Foundry Sand

    Directory of Open Access Journals (Sweden)

    Krajewski P.K.

    2015-06-01

    Full Text Available The paper presents results of measuring thermal conductivity and heat capacity of bentonite foundry sand in temperature range ambient - 900­­°C. During the experiments a technical purity Cu plate was cast into the green-sand moulds. Basing on measurements of the mould temperature field during the solidification of the casting, the temperature relationships of the measured properties were evaluated. It was confirmed that water vaporization strongly influences thermal conductivity of the moulding sand in the first period of the mould heating by the poured casting.

  18. Development of Thermally Actuated, High Temperature Composite Morphing Concepts

    Science.gov (United States)

    2016-03-31

    set of applications exists in gas turbine engines, which stand to benefit greatly from aerodynamic control in their combustors, turbines, and nozzles...Modelling Development 27 3.1 Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.1.1 Achieving Snap-Through Behaviour ...Fabrication of Hybrid Laminate Shell and Strip Specimens . . . . . . 35 3.3.2 Measurement of Thermal Curvatures and Snap-Through Behaviour of Hybrid

  19. Development of Thermally Actuated, High-Temperature Composite Morphing Concepts

    Science.gov (United States)

    2016-05-11

    set of applications exists in gas turbine engines, which stand to benefit greatly from aerodynamic control in their combustors, turbines, and nozzles...Modelling Development 27 3.1 Mechanics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28 3.1.1 Achieving Snap-Through Behaviour ...Fabrication of Hybrid Laminate Shell and Strip Specimens . . . . . . 35 3.3.2 Measurement of Thermal Curvatures and Snap-Through Behaviour of Hybrid

  20. Fused silica thermal conductivity dispersion at high temperature

    International Nuclear Information System (INIS)

    Bouchut, P.; Decruppe, D.; Delrive, L.

    2004-01-01

    A continuous CO 2 laser is focused to locally anneal small fused silica spots. A noncontact radiometry diagnostic enables us to follow surface temperature variation that occurs from site to site. A 'steady state' dispersion of surface temperature is observed across our sample. We show that nonhomogeneous silica thermal conductivity, above 1000 K is responsible for this temperature dispersion

  1. Estimated Viscosities and Thermal Conductivities of Gases at High Temperatures

    Science.gov (United States)

    Svehla, Roger A.

    1962-01-01

    Viscosities and thermal conductivities, suitable for heat-transfer calculations, were estimated for about 200 gases in the ground state from 100 to 5000 K and 1-atmosphere pressure. Free radicals were included, but excited states and ions were not. Calculations for the transport coefficients were based upon the Lennard-Jones (12-6) potential for all gases. This potential was selected because: (1) It is one of the most realistic models available and (2) intermolecular force constants can be estimated from physical properties or by other techniques when experimental data are not available; such methods for estimating force constants are not as readily available for other potentials. When experimental viscosity data were available, they were used to obtain the force constants; otherwise the constants were estimated. These constants were then used to calculate both the viscosities and thermal conductivities tabulated in this report. For thermal conductivities of polyatomic gases an Eucken-type correction was made to correct for exchange between internal and translational energies. Though this correction may be rather poor at low temperatures, it becomes more satisfactory with increasing temperature. It was not possible to obtain force constants from experimental thermal conductivity data except for the inert atoms, because most conductivity data are available at low temperatures only (200 to 400 K), the temperature range where the Eucken correction is probably most in error. However, if the same set of force constants is used for both viscosity and thermal conductivity, there is a large degree of cancellation of error when these properties are used in heat-transfer equations such as the Dittus-Boelter equation. It is therefore concluded that the properties tabulated in this report are suitable for heat-transfer calculations of gaseous systems.

  2. Nuclear reactor vessel fuel thermal insulating barrier

    Science.gov (United States)

    Keegan, C. Patrick; Scobel, James H.; Wright, Richard F.

    2013-03-19

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel that has a hemispherical lower section that increases in volume from the center line of the reactor to the outer extent of the diameter of the thermal insulating barrier and smoothly transitions up the side walls of the vessel. The space between the thermal insulating harrier and the reactor vessel forms a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive inlet valve for the cooling water includes a buoyant door that is normally maintained sealed under its own weight and floats open when the cavity is Hooded. Passively opening steam vents are also provided.

  3. Artificial heart system thermal insulation component development

    International Nuclear Information System (INIS)

    Svedberg, R.C.; Buckman, R.W. Jr.

    1975-01-01

    A concentric cup vacuum multifoil insulation system has been selected by virtue of its size, weight, and thermal performance to insulate the hot radioisotope portion of the thermal converter of an artificial implantable heart system. A factor of 2 improvement in thermal performance, based on the heat loss per number of foil layers (minimum system weight and volume) has been realized over conventional spiral wrapped multifoil vacuum insulation. This improvement is the result of the concentric cup construction to maintain a uniform interfoil spacing and the elimination of corner heat losses. Based on external insulation system dimensions (surface area in contact with host body), heat losses of 0.019 W/ cm 2 at 1140 0 K (1600 0 F) and 0.006 W/cm 2 at 920 0 K (1200 0 F) have been achieved. Factors which influence thermal performance of the nickel foil concentric cup insulation system include the number of cups, configuration and method of application of zirconia (ZrO 2 ) spacer material, system pressure, emittance of the cups, and operating temperature

  4. Optically Transparent Thermally Insulating Silica Aerogels for Solar Thermal Insulation.

    Science.gov (United States)

    Günay, A Alperen; Kim, Hannah; Nagarajan, Naveen; Lopez, Mateusz; Kantharaj, Rajath; Alsaati, Albraa; Marconnet, Amy; Lenert, Andrej; Miljkovic, Nenad

    2018-04-18

    Rooftop solar thermal collectors have the potential to meet residential heating demands if deployed efficiently at low solar irradiance (i.e., 1 sun). The efficiency of solar thermal collectors depends on their ability to absorb incoming solar energy and minimize thermal losses. Most techniques utilize a vacuum gap between the solar absorber and the surroundings to eliminate conduction and convection losses, in combination with surface coatings to minimize reradiation losses. Here, we present an alternative approach that operates at atmospheric pressure with simple, black, absorbing surfaces. Silica based aerogels coated on black surfaces have the potential to act as simple and inexpensive solar thermal collectors because of their high transmission to solar radiation and low transmission to thermal radiation. To demonstrate their heat-trapping properties, we fabricated tetramethyl orthosilicate-based silica aerogels. A hydrophilic aerogel with a thickness of 1 cm exhibited a solar-averaged transmission of 76% and thermally averaged transmission of ≈1% (at 100 °C). To minimize unwanted solar absorption by O-H groups, we functionalized the aerogel to be hydrophobic, resulting in a solar-averaged transmission of 88%. To provide a deeper understanding of the link between aerogel properties and overall efficiency, we developed a coupled radiative-conductive heat transfer model and used it to predict solar thermal performance. Instantaneous solar thermal efficiencies approaching 55% at 1 sun and 80 °C were predicted. This study sheds light on the applicability of silica aerogels on black coatings for solar thermal collectors and offers design priorities for next-generation solar thermal aerogels.

  5. Facility for endurance tests of thermal insulations

    International Nuclear Information System (INIS)

    Mauersberger, R.

    1984-01-01

    In the following report the design and construction of an experimental facility for endurance tests of thermal insulations is presented. It's name in abbreviation is 'ADI' standing for the German words A nlage zum Dauertest von Isolierungen . This test facility was build by HRB in order to investigate the performance of thermal insulation systems of hot gas ducts for the process heat-reactor-project. The tests are intended to simulate the conditions of reactor operation. They include short-time experiments for selection of insulation-concepts and in a second step long-time experiments as performance tests. During these tests are measured the effective heat conductivity the local heat losses the temperature profiles of the insulation, of the fixing elements and along the wall of the duct. The design-data required to perform all these tasks are shown in the first picture: The gas-atmosphere must be Helium in tests like in reactor with regard to the special thermal and hydraulic properties of Helium and to the influence of Helium on mechanic friction and wear. The hot gas temperature in the PNP-reactor will be 950 deg. C and should be equal in the experiments. The temperature on the cold side of the insulation has to be adjustable from 50 deg. C up to 300 deg. C. The Helium pressure in the hot gas ducts of a HTR-plant is about 42 bar. The ADI was laid out for 70 bar to cover the hole range of interest. A Helium mass flow has to stream through the insulated test duct in order to realize equal temperatures on the hot side of the insulation. A flow rate of 4,5 kg/s is sufficient for this requirement. The axial pressure gradient along the insulation must be the same as in the reactor, because this has an essential influence on the heat losses. This pressure gradient is about 40 Pa/m

  6. Soup Cooking by Thermal Insulation Method

    OpenAIRE

    佐藤, 辰江; 根本, 勢子; サトウ, タツエ; ネモト, セイコ; TATSUE, SATO; SEIKO, NEMOTO

    1992-01-01

    In order to examine the thermal insulation method of soup cooking, we cooked two kinds of soup. The soup cooked by thermal insulation method was compared with the soup cooked by standard boiling method. ln sensory test, it was more aromatic and palatable than the soup by boiling, and some panels commented that it was rather mild. The measured values of pH, specific gravity, acidity and amount of dry weight of souble solids, total-N, formal-N of the soup cooked by the two methods mentioned abo...

  7. An Angle Resolved Photoemission Study of a Mott Insulator and Its Evolution to a High Temperature Superconductor

    Energy Technology Data Exchange (ETDEWEB)

    Ronning, Filip

    2002-03-19

    One of the most remarkable facts about the high temperature superconductors is their close proximity to an antiferromagnetically ordered Mott insulating phase. This fact suggests that to understand superconductivity in the cuprates we must first understand the insulating regime. Due to material properties the technique of angle resolved photoemission is ideally suited to study the electronic structure in the cuprates. Thus, a natural starting place to unlocking the secrets of high Tc would appears to be with a photoemission investigation of insulating cuprates. This dissertation presents the results of precisely such a study. In particular, we have focused on the compound Ca{sub 2-x}Na{sub x}CuO{sub 2}Cl{sub 2}. With increasing Na content this system goes from an antiferromagnetic Mott insulator with a Neel transition of 256K to a superconductor with an optimal transition temperature of 28K. At half filling we have found an asymmetry in the integrated spectral weight, which can be related to the occupation probability, n(k). This has led us to identify a d-wave-like dispersion in the insulator, which in turn implies that the high energy pseudogap as seen by photoemission is a remnant property of the insulator. These results are robust features of the insulator which we found in many different compounds and experimental conditions. By adding Na we were able to study the evolution of the electronic structure across the insulator to metal transition. We found that the chemical potential shifts as holes are doped into the system. This picture is in sharp contrast to the case of La{sub 2-x}Sr{sub x}CuO{sub 4} where the chemical potential remains fixed and states are created inside the gap. Furthermore, the low energy excitations (ie the Fermi surface) in metallic Ca{sub 1.9}Na{sub 0.1}CuO{sub 2}Cl{sub 2} is most well described as a Fermi arc, although the high binding energy features reveal the presence of shadow bands. Thus, the results in this dissertation provide a

  8. Refractory porcelain enamel passive-thermal-control coating for high-temperature superalloys

    Science.gov (United States)

    Levin, H.; Auker, B. H.; Gardos, M. N.

    1973-01-01

    Study was conducted to match thermal expansion coefficients thereby preventing enamels from cracking. Report discusses various enamel coatings that are applied to two different high-temperature superalloys. Study may be of interest to manufacturers of chemical equipment, furnaces, and metal components intended for high-temperature applications.

  9. High temperature study of flexible silicon-on-insulator fin field-effect transistors

    KAUST Repository

    Diab, Amer El Hajj; Sevilla, Galo T.; Ghoneim, Mohamed T.; Hussain, Muhammad Mustafa

    2014-01-01

    . Characterization from room to high temperature (150 °C) was completed to determine temperature dependence of drain current (Ids), gate leakage current (Igs), transconductance (gm), and extracted low-field mobility (μ0). Mobility degradation with temperature

  10. Thermal insulation performance of green roof systems

    Energy Technology Data Exchange (ETDEWEB)

    Celik, Serdar; Morgan, Susan; Retzlaff, William; Once, Orcun [southern Illinois University (United States)], e-mail: scelik@siue.edu, e-mail: smorgan@siue.edu, e-mail: wretzla@siue.edu, e-mail: oonce@siue.edu

    2011-07-01

    With the increasing costs of energy, good building insulation has become increasingly important. Among existing insulation techniques is the green roof system, which consists of covering the roof of a building envelop with plants. The aim of this paper is to assess the impact of vegetation type and growth media on the thermal performance of green roof systems. Twelve different green roof samples were made with 4 different growth media and 3 sedum types. Temperature at the sample base was recorded every 15 minutes for 3 years; the insulation behavior was then analysed. Results showed that the insulation characteristics were achieved with a combination of haydite and sedum sexangulare. This study demonstrated that the choice of growth media and vegetation is important to the green roof system's performance; further research is required to better understand the interactions between growth media and plant roots.

  11. Sintering Characteristics of Multilayered Thermal Barrier Coatings Under Thermal Gradient and Isothermal High Temperature Annealing Conditions

    Science.gov (United States)

    Rai, Amarendra K.; Schmitt, Michael P.; Bhattacharya, Rabi; Zhu, Dongming; Wolfe, Douglas E.

    2014-01-01

    Pyrochlore oxides have most of the relevant attributes for use as next generation thermal barrier coatings such as phase stability, low sintering kinetics and low thermal conductivity. One of the issues with the pyrochlore oxides is their lower toughness and therefore higher erosion rate compared to the current state-of-the-art TBC material, yttria (6 to 8 wt%) stabilized zirconia (YSZ). In this work, sintering characteristics were investigated for novel multilayered coating consisted of alternating layers of pyrochlore oxide viz Gd2Zr2O7 and t' low k (rare earth oxide doped YSZ). Thermal gradient and isothermal high temperature (1316 C) annealing conditions were used to investigate sintering and cracking in these coatings. The results are then compared with that of relevant monolayered coatings and a baseline YSZ coating.

  12. Near-Field Thermal Radiation for Solar Thermophotovoltaics and High Temperature Thermal Logic and Memory Applications

    Science.gov (United States)

    Elzouka, Mahmoud

    This dissertation investigates Near-Field Thermal Radiation (NFTR) applied to MEMS-based concentrated solar thermophotovoltaics (STPV) energy conversion and thermal memory and logics. NFTR is the exchange of thermal radiation energy at nano/microscale; when separation between the hot and cold objects is less than dominant radiation wavelength (˜1 mum). NFTR is particularly of interest to the above applications due to its high rate of energy transfer, exceeding the blackbody limit by orders of magnitude, and its strong dependence on separation gap size, surface nano/microstructure and material properties. Concentrated STPV system converts solar radiation to electricity using heat as an intermediary through a thermally coupled absorber/emitter, which causes STPV to have one of the highest solar-to-electricity conversion efficiency limits (85.4%). Modeling of a near-field concentrated STPV microsystem is carried out to investigate the use of STPV based solid-state energy conversion as high power density MEMS power generator. Numerical results for In 0.18Ga0.82Sb PV cell illuminated with tungsten emitter showed significant enhancement in energy transfer, resulting in output power densities as high as 60 W/cm2; 30 times higher than the equivalent far-field power density. On thermal computing, this dissertation demonstrates near-field heat transfer enabled high temperature NanoThermoMechanical memory and logics. Unlike electronics, NanoThermoMechanical memory and logic devices use heat instead of electricity to record and process data; hence they can operate in harsh environments where electronics typically fail. NanoThermoMechanical devices achieve memory and thermal rectification functions through the coupling of near-field thermal radiation and thermal expansion in microstructures, resulting in nonlinear heat transfer between two temperature terminals. Numerical modeling of a conceptual NanoThermoMechanical is carried out; results include the dynamic response under

  13. Handbook of Thermal Insulation Applications.

    Science.gov (United States)

    1983-01-01

    Wiuppuoror *tIe beamsWiefag ln~ td ~oair ilmstool beams Plate 18. Metal Building Ceilings - A 18b: Fir* hataird rathge may limit the use of foam Insulation...RFCTANGUI.AR SOL TD A = 2(WxL+LxH+HxW) B V = WxLxH H L TRAPEZOID A 2 (A + B) x H A CONE A -n xRxS+ i xR 2 B V =( /3)x R2 x H TRIANGLE A BxH A- 2 CYLI NDER H 2...FABRICATIIG RECTANGULAR HEATING AND COOLING DUCTWORK. FIBERGLAS DUCT BOARD OWENS-CORNING FIBERGLAS CORP GLASS FIBER RIGID BOARD WITH ALUMINUM 4bD FOIL VAPOR

  14. Layered Thermal Insulation Systems for Industrial and Commercial Applications

    Science.gov (United States)

    Fesmire, James E.

    2015-01-01

    From the high performance arena of cryogenic equipment, several different layered thermal insulation systems have been developed for industrial and commercial applications. In addition to the proven areas in cold-work applications for piping and tanks, the new Layered Composite Insulation for Extreme Environments (LCX) has potential for broader industrial use as well as for commercial applications. The LCX technology provides a unique combination of thermal, mechanical, and weathering performance capability that is both cost-effective and enabling. Industry applications may include, for example, liquid nitrogen (LN2) systems for food processing, liquefied natural gas (LNG) systems for transportation or power, and chilled water cooling facilities. Example commercial applications may include commercial residential building construction, hot water piping, HVAC systems, refrigerated trucks, cold chain shipping containers, and a various consumer products. The LCX system is highly tailorable to the end-use application and can be pre-fabricated or field assembled as needed. Product forms of LCX include rigid sheets, semi-flexible sheets, cylindrical clam-shells, removable covers, or flexible strips for wrapping. With increasing system control and reliability requirements as well as demands for higher energy efficiencies, thermal insulation in harsh environments is a growing challenge. The LCX technology grew out of solving problems in the insulation of mechanically complex cryogenic systems that must operate in outdoor, humid conditions. Insulation for cold work includes equipment for everything from liquid helium to chilled water. And in the middle are systems for LNG, LN2, liquid oxygen (LO2), liquid hydrogen (LH2) that must operate in the ambient environment. Different LCX systems have been demonstrated for sub-ambient conditions but are capable of moderately high temperature applications as well.

  15. Measurement of the Thermal Expansion Coefficient for Ultra-High Temperatures up to 3000 K

    Science.gov (United States)

    Kompan, T. A.; Kondratiev, S. V.; Korenev, A. S.; Puhov, N. F.; Inochkin, F. M.; Kruglov, S. K.; Bronshtein, I. G.

    2018-03-01

    The paper is devoted to a new high-temperature dilatometer, a part of the State Primary Standard of the thermal expansion coefficient (TEC) unit. The dilatometer is designed for investigation and certification of materials for TEC standards in the range of extremely high temperatures. The critical review of existing methods of TEC measurements is given. Also, the design, principles of operation and metrological parameters of the new device are described. The main attention is paid to the system of machine vision that allows accurate measurement of elongation at high temperatures. The results of TEC measurements for graphite GIP-4, single crystal Al2O3, and some other materials are also presented.

  16. Thermal insulator made of ultra fine particles of silica. Chobiryushi silica kei dannetsuzai

    Energy Technology Data Exchange (ETDEWEB)

    Eguchi, T.

    1991-05-30

    An overview was presented of properties and applications of thermal insulator made of ultra fine powder of silica, MICROTHERM. The thermal conductivity of MICROTHERM is as low as (1/3) - (1/4) of that of conventional thermal insulator, because it is mainly composed of fumed silica or aero gel and formed into porous structure. In addition, metal oxide of special particle size is added to it in order to reject the radiative heat. The thermal insulation property and the mechanical strength of MICROTHERM is not affected by a sudden change in temperature and moisture. The standard type of MICROTHERM can be used at a temperature up to 950 {degree}C, while the high temperature type MICROTHERM can stand a high temperature up to 1025 {degree}C for long period of time. The thickness of insulator can be reduced markedly by using MICROTHERM as compared with the use of conventional insulating materials. Many new products in which MICROTHERM is used came into market. New type kilt, Semi-cylindrical block, Super high temperature MICROTHERM are just a few examples. Variety of application and energy saving effect are attracting public attention. 11 figs.

  17. Building ceramics with improved thermal insulation parameters

    Directory of Open Access Journals (Sweden)

    Rzepa Karol

    2016-01-01

    Full Text Available One of the most important performance characteristics of masonry units is their high thermal insulation. There are many different ways to improve this parameter, however the most popular methods in case of ceramic masonry units are: addition of pore-creating raw materials and application of proper hole pattern. This study was an attempt to improve thermal insulation of ceramics by applying thermal insulation additives. Perlite dust created as a subgrain from expansion of perlite rock was used. Perlite subgrain is not very popular among consumers, that’s why it’s subjected to granulation to obtain coarse grain. The authors presented concept of direct application of perlite dust for the production of building ceramics with improved thermal insulation. Fineness of this additive is asset for molding of ceramic materials from plastic masses. Based on the results it was found that about 70% perlite by volume can be added to obtain material with a coefficient of heat conductivity of 0,37 W/mK. Higher content of this additive in ceramic mass causes deterioration of its rheological properties. Mass loses its plasticity, it tears up and formed green bodies are susceptible to deformation. During sintering perlite takes an active part in compaction process. Higher sintering dynamics is caused by: high content of alkali oxides in perlite and glass nature of perlite. Alkali oxides generate creation of liquid phase which intensifies mass compaction processes. Active role of perlite in sintering process causes good connection of its grains with clay groundwork which is important factor for mechanical parameters of ceramic materials. It was also noted that addition of perlite above 40% by volume of mass effectively neutralized negative effect of efflorescence in ceramic materials.

  18. Graded thermal insulation layer systems; Gradierte Waermedaemmschichtsysteme

    Energy Technology Data Exchange (ETDEWEB)

    Leushake, U.; Krell, T. [Deutsche Forschungsanstalt fuer Luft- und Raumfahrt e.V. (DLR), Koeln (Germany). Inst. fuer Werkstoff-Forschung

    1996-12-31

    Graded thermal insulation systems reduce local stresses between two layers. Grading usually involves a concentration variation in a second phase but may also involve variations of the microstructure or chemical composition. The contribution discusses the application of this technique for thermal protection of turbine blades in aircraft propulsion systems. [Deutsch] Mit Hilfe gradierter Waermeschichtsysteme ist es moeglich die lokalen Spannungen zwischen zwei Schichten zu verringern. Die Gradierung umfasst meistens eine Variation des Gehaltes einer zweiten Phase, kann aber auch die Variation der Mikrostruktur oder der chemischen Zusammensetzung beinhalten. In diesem Beitrag wird auf die Anwendung als thermischer Schutz von Turbinenschaufeln fuer Flugtriebwerke eingegangen.

  19. High-Temperature Adhesives for Thermally Stable Aero-Assist Technologies

    Science.gov (United States)

    Eberts, Kenneth; Ou, Runqing

    2013-01-01

    Aero-assist technologies are used to control the velocity of exploration vehicles (EVs) when entering Earth or other planetary atmospheres. Since entry of EVs in planetary atmospheres results in significant heating, thermally stable aero-assist technologies are required to avoid the high heating rates while maintaining low mass. Polymer adhesives are used in aero-assist structures because of the need for high flexibility and good bonding between layers of polymer films or fabrics. However, current polymer adhesives cannot withstand temperatures above 400 C. This innovation utilizes nanotechnology capabilities to address this need, leading to the development of high-temperature adhesives that exhibit high thermal conductivity in addition to increased thermal decomposition temperature. Enhanced thermal conductivity will help to dissipate heat quickly and effectively to avoid temperature rising to harmful levels. This, together with increased thermal decomposition temperature, will enable the adhesives to sustain transient high-temperature conditions.

  20. Overview of thermal conductivity models of anisotropic thermal insulation materials

    Science.gov (United States)

    Skurikhin, A. V.; Kostanovsky, A. V.

    2017-11-01

    Currently, the most of existing materials and substances under elaboration are anisotropic. It makes certain difficulties in the study of heat transfer process. Thermal conductivity of the materials can be characterized by tensor of the second order. Also, the parallelism between the temperature gradient vector and the density of heat flow vector is violated in anisotropic thermal insulation materials (TIM). One of the most famous TIM is a family of integrated thermal insulation refractory material («ITIRM»). The main component ensuring its properties is the «inflated» vermiculite. Natural mineral vermiculite is ground into powder state, fired by gas burner for dehydration, and its precipitate is then compressed. The key feature of thus treated batch of vermiculite is a package structure. The properties of the material lead to a slow heating of manufactured products due to low absorption and high radiation reflection. The maximum of reflection function is referred to infrared spectral region. A review of current models of heat propagation in anisotropic thermal insulation materials is carried out, as well as analysis of their thermal and optical properties. A theoretical model, which allows to determine the heat conductivity «ITIRM», can be useful in the study of thermal characteristics such as specific heat capacity, temperature conductivity, and others. Materials as «ITIRM» can be used in the metallurgy industry, thermal energy and nuclear power-engineering.

  1. Thermally-insulating layer for nuclear reactors

    International Nuclear Information System (INIS)

    1975-01-01

    The thermally-insulating layer has been designed both for insulating surfaces within the core of a nuclear reactor and transmitting loads such as the core-weight. Said layer comprises a layer of bricks and a layer of tiles with smaller clearance between the tiles than between the bricks, the latter having a reduced cross-section against the tiles so as to be surrounded by relatively large interconnected ducts forming a continuous chamber behind the tile-layer in order to induce a substantial decreases in the transverse flow of the reactor-core coolant. The core preferably comprises hexagonal columns supported by rhomb-shaped plates, with channels distributed so as to mix the coolant of twelve columns. The plates are separated from support-tiles by means of pillars [fr

  2. High Temperature Exposure of HPC – Experimental Analysis of Residual Properties and Thermal Response

    Directory of Open Access Journals (Sweden)

    Pavlík Zbyšek

    2016-01-01

    Full Text Available The effect of high temperature exposure on properties of a newly designed High Performance Concrete (HPC is studied in the paper. The HPC samples are exposed to the temperatures of 200, 400, 600, 800, and 1000°C respectively. Among the basic physical properties, bulk density, matrix density and total open porosity are measured. The mechanical resistivity against disruptive temperature action is characterised by compressive strength, flexural strength and dynamic modulus of elasticity. To study the chemical and physical processes in HPC during its high-temperature exposure, Simultaneous Thermal Analysis (STA is performed. Linear thermal expansion coefficient is determined as function of temperature using thermodilatometry (TDA. In order to describe the changes in microstructure of HPC induced by high temperature loading, MIP measurement of pore size distribution is done. Increase of the total open porosity and connected decrease of the mechanical parameters for temperatures higher than 200 °C were identified.

  3. Measuring technique of super high temperature thermal properties of reactor core materials

    International Nuclear Information System (INIS)

    Ono, Akira; Baba, Tetsuya; Watanabe, Hideo; Matsumoto, Tsuyoshi

    1998-01-01

    In this study, thermal properties of reactor core materials used for water cooled reactors and FBR were tried to develop a technique to measure their melt states at less than 3,000degC in order to contribute more correct evaluation of the reactor core behavior at severe accident. Then, a thermal property measuring method of high temperature melt by using floating method was investigated and its fundamental design was begun to investigate under a base of optimum judgement on the air flow floating throw-down method. And, in order to measure emissivity of melt specimen surface essential for correct temperature measurement using the throw down method, a spectroscopic emissivity measuring unit using an ellipsometer was prepared and induced. On the thermal properties measurement using the holding method, a specimen container to measure thermal diffusiveness of the high temperature melts by using laser flashing method was tried to prepare. (G.K.)

  4. Thermal Stability of Hexamethyldisiloxane (MM for High-Temperature Organic Rankine Cycle (ORC

    Directory of Open Access Journals (Sweden)

    Markus Preißinger

    2016-03-01

    Full Text Available The design of efficient Organic Rankine Cycle (ORC units for the usage of industrial waste heat at high temperatures requires direct contact evaporators without intermediate thermal oil circuits. Therefore, the thermal stability of high-temperature working fluids gains importance. In this study, the thermal degradation of hexamethyldisiloxane (MM is investigated in an electrically heated tube. Qualitative results concerning remarks on degradation products as well as quantitative results like the annual degradation rate are presented. It is shown that MM is stable up to a temperature of 300 °C with annual degradation rates of less than 3.5%. Furthermore, the break of a silicon–carbon bond can be a main chemical reaction that influences the thermal degradation. Finally, it is discussed how the results may impact the future design of ORC units.

  5. Rapid Thermal Annealing of Cathode-Garnet Interface toward High-Temperature Solid State Batteries.

    Science.gov (United States)

    Liu, Boyang; Fu, Kun; Gong, Yunhui; Yang, Chunpeng; Yao, Yonggang; Wang, Yanbin; Wang, Chengwei; Kuang, Yudi; Pastel, Glenn; Xie, Hua; Wachsman, Eric D; Hu, Liangbing

    2017-08-09

    High-temperature batteries require the battery components to be thermally stable and function properly at high temperatures. Conventional batteries have high-temperature safety issues such as thermal runaway, which are mainly attributed to the properties of liquid organic electrolytes such as low boiling points and high flammability. In this work, we demonstrate a truly all-solid-state high-temperature battery using a thermally stable garnet solid-state electrolyte, a lithium metal anode, and a V 2 O 5 cathode, which can operate well at 100 °C. To address the high interfacial resistance between the solid electrolyte and cathode, a rapid thermal annealing method was developed to melt the cathode and form a continuous contact. The resulting interfacial resistance of the solid electrolyte and V 2 O 5 cathode was significantly decreased from 2.5 × 10 4 to 71 Ω·cm 2 at room temperature and from 170 to 31 Ω·cm 2 at 100 °C. Additionally, the diffusion resistance in the V 2 O 5 cathode significantly decreased as well. The demonstrated high-temperature solid-state full cell has an interfacial resistance of 45 Ω·cm 2 and 97% Coulombic efficiency cycling at 100 °C. This work provides a strategy to develop high-temperature all-solid-state batteries using garnet solid electrolytes and successfully addresses the high contact resistance between the V 2 O 5 cathode and garnet solid electrolyte without compromising battery safety or performance.

  6. High-temperature stability of yttria-stabilized zirconia thermal barrier ...

    Indian Academy of Sciences (India)

    The coatings before and after IR heating were investigated by scanning electron microscopy, X-ray diffraction, electron probe microanalysis, microhardness and residual stress measurements in order to understand the effect of thermal shock on the properties of the TBC. On account of these high-temperature properties, ...

  7. Critical currents and thermally activated flux motion in high-temperature superconductors

    NARCIS (Netherlands)

    Palstra, T.T.M.; Batlogg, B.; Dover, R.B. van; Schneemeyer, L.F.; Waszczak, J.V.

    1989-01-01

    We have measured the resistance below Tc of single crystals of the high-temperature superconductors Ba2YCu3O7 and Bi2.2Sr2Ca0.8Cu2O8+δ in magnetic fields up to 12 T. The resistive transition of both compounds is dominated by intrinsic dissipation which is thermally activated, resulting in an

  8. Thermal-hydraulic code selection for modular high temperature gas-cooled reactors

    Energy Technology Data Exchange (ETDEWEB)

    Komen, E M.J.; Bogaard, J.P.A. van den

    1995-06-01

    In order to study the transient thermal-hydraulic system behaviour of modular high temperature gas-cooled reactors, the thermal-hydraulic computer codes RELAP5, MELCOR, THATCH, MORECA, and VSOP are considered at the Netherlands Energy Research Foundation ECN. This report presents the selection of the most appropriate codes. To cover the range of relevant accidents, a suite of three codes is recommended for analyses of HTR-M and MHTGR reactors. (orig.).

  9. Using of Aerogel to Improve Thermal Insulating Properties of Windows

    Science.gov (United States)

    Valachova, Denisa; Zdrazilova, Nada; Panovec, Vladan; Skotnicova, Iveta

    2018-06-01

    For the best possible thermal-technical properties of building structures it is necessary to use materials with very low thermal conductivity. Due to the increasing thermal-technical requirements for building structures, the insulating materials are developed. One of the modern thermal insulating materials is so-called aerogel. Unfortunately, this material is not used in the field of external thermal insulation composite systems because of its price and its properties. The aim of this paper is to present possibilities of using this insulating material in the civil engineering - specifically a usage of aerogel in the production of windows.

  10. Advances in Thermal Insulation. Vacuum Insulation Panels and Thermal Efficiency to Reduce Energy Usage in Buildings

    Energy Technology Data Exchange (ETDEWEB)

    Thorsell, Thomas

    2012-07-01

    We are coming to realize that there is an urgent need to reduce energy usage in buildings and it has to be done in a sustainable way. This thesis focuses on the performance of the building envelope; more precisely thermal performance of walls and super insulation material in the form of vacuum insulation. However, the building envelope is just one part of the whole building system, and super insulators have one major flaw: they are easily adversely affected by other problems in the built environment. Vacuum Insulation Panels are one fresh addition to the arsenal of insulation materials available to the building industry. They are composite material with a core and an enclosure which, as a composite, can reach thermal conductivities as low as 0.004 W/(mK). However, the exceptional performance relies on the barrier material preventing gas permeation, maintaining a near vacuum into the core and a minimized thermal bridge effect from the wrapping of barrier material round the edge of a panel. A serpentine edge is proposed to decrease the heat loss at the edge. Modeling and testing shows a reduction of 60 % if a reasonable serpentine edge is used. A diffusion model of permeation through multilayered barrier films with metallization coatings was developed to predict ultimate service life. The model combines numerical calculations with analytical field theory allowing for more precise determination than current models. The results using the proposed model indicate that it is possible to manufacture panels with lifetimes exceeding 50 years with existing manufacturing. Switching from the component scale to the building scale; an approach of integrated testing and modeling is proposed. Four wall types have been tested in a large range of environments with the aim to assess the hydrothermal nature and significance of thermal bridges and air leakages. The test procedure was also examined as a means for a more representative performance indicator than R-value (in USA). The

  11. Transcriptomic study to understand thermal adaptation in a high temperature-tolerant strain of Pyropia haitanensis.

    Science.gov (United States)

    Wang, Wenlei; Teng, Fei; Lin, Yinghui; Ji, Dehua; Xu, Yan; Chen, Changsheng; Xie, Chaotian

    2018-01-01

    Pyropia haitanensis, a high-yield commercial seaweed in China, is currently undergoing increasing levels of high-temperature stress due to gradual global warming. The mechanisms of plant responses to high temperature stress vary with not only plant type but also the degree and duration of high temperature. To understand the mechanism underlying thermal tolerance in P. haitanensis, gene expression and regulation in response to short- and long-term temperature stresses (SHS and LHS) was investigated by performing genome-wide high-throughput transcriptomic sequencing for a high temperature tolerant strain (HTT). A total of 14,164 differential expression genes were identified to be high temperature-responsive in at least one time point by high-temperature treatment, representing 41.10% of the total number of unigenes. The present data indicated a decrease in the photosynthetic and energy metabolic rates in HTT to reduce unnecessary energy consumption, which in turn facilitated in the rapid establishment of acclimatory homeostasis in its transcriptome during SHS. On the other hand, an increase in energy consumption and antioxidant substance activity was observed with LHS, which apparently facilitates in the development of resistance against severe oxidative stress. Meanwhile, ubiquitin-mediated proteolysis, brassinosteroids, and heat shock proteins also play a vital role in HTT. The effects of SHS and LHS on the mechanism of HTT to resist heat stress were relatively different. The findings may facilitate further studies on gene discovery and the molecular mechanisms underlying high-temperature tolerance in P. haitanensis, as well as allow improvement of breeding schemes for high temperature-tolerant macroalgae that can resist global warming.

  12. Experimental investigation of thermal de-stratification in rock bed TES systems for high temperature applications

    International Nuclear Information System (INIS)

    Okello, Denis; Nydal, Ole J.; Banda, Eldad J.K.

    2014-01-01

    Highlights: • High thermal stratifications exists rock bed TES when charge with high temperature heat. • Faster thermal degradation occurs in highly stratified bed irrespective of the bed length. • Average rate of heat loss as a function of storage time increases with increasing average bed temperature. - Abstract: Solar energy fluctuates so much that it cannot promote continuous use. Integration of Thermal Energy Storage (TES) with solar energy collection devices has the potential of making solar energy available on demand. Thermal energy can be stored in a bed of rocks at temperatures suitable for applications like cooking, boiling space heating, etc. During charging, temperature stratification is observed in the bed. In a stratified system, if the heat is used immediately, then it is possible to extract heat at reasonably high temperature from the top. For cases where the system is to be used after sometime (later at night or the following morning), the high temperature heat at the top is observed to degrade as the system tries to establish thermal equilibrium irrespective of the bed height. The average rate of heat loss from the TES unit to the ambient is found to increase with increasing average bed temperatures

  13. Solidification of high temperature molten salts for thermal energy storage systems

    Science.gov (United States)

    Sheffield, J. W.

    1981-01-01

    The solidification of phase change materials for the high temperature thermal energy storage system of an advanced solar thermal power system has been examined theoretically. In light of the particular thermophysical properties of candidate phase change high temperature salts, such as the eutectic mixture of NaF - MgF2, the heat transfer characteristics of one-dimensional inward solidification for a cylindrical geometry have been studied. The Biot number for the solidified salt is shown to be the critical design parameter for constant extraction heat flux. A fin-on-fin design concept of heat transfer surface augmentation is proposed in an effort to minimize the effects of the salt's low thermal conductivity and large volume change upon fusing.

  14. Experiment on thermal insulation and sodium deposition of shield plug

    International Nuclear Information System (INIS)

    Hashiguchi, K.; Honda, M.; Shiratori, H.; Ozaki, O.; Suzuki, M.

    1986-01-01

    A series of experiments on temperature distribution and thermal insulation characteristics was conducted using a reduced scale model of LMFBR shield plug. Observation and measurement of sodium deposition were also conducted on the model after the experiment. The effect of annulus natural convection was clarified for temperature and the thermal insulation characteristics from evaluating the result. Temperature distribution analysis was conducted successfully by combining the general purpose structural analysis program NASTRAN and vertical annulus natural convection analysis program VANAC. Moreover, significant effect was substantiated for the annulus convection barrier to increase the thermal insulation performance, narrow horizontal gap structure to prevent sodium deposition and thermal insulation plates. (author)

  15. Thermal insulation coating based on water-based polymer dispersion

    Directory of Open Access Journals (Sweden)

    Panchenko Iuliia

    2018-01-01

    Full Text Available For Russia, due to its long winter period, improvement of thermal insulation properties of envelope structures by applying thermal insulation paint and varnish coating to its inner surface is considered perspective. Thermal insulation properties of such coatings are provided by adding aluminosilicate microspheres and aluminum pigment to their composition. This study was focused on defining the effect of hollow aluminosilicate microspheres and aluminum pigment on the paint thermal insulation coating based on water-based polymer dispersion and on its optimum filling ratio. The optimum filling ratio was determined using the method of critical pigment volume concentration (CPVC. The optimum filling ratio was found equal to 55%.

  16. Thermal analysis of heat and power plant with high temperature reactor and intermediate steam cycle

    Directory of Open Access Journals (Sweden)

    Fic Adam

    2015-03-01

    Full Text Available Thermal analysis of a heat and power plant with a high temperature gas cooled nuclear reactor is presented. The main aim of the considered system is to supply a technological process with the heat at suitably high temperature level. The considered unit is also used to produce electricity. The high temperature helium cooled nuclear reactor is the primary heat source in the system, which consists of: the reactor cooling cycle, the steam cycle and the gas heat pump cycle. Helium used as a carrier in the first cycle (classic Brayton cycle, which includes the reactor, delivers heat in a steam generator to produce superheated steam with required parameters of the intermediate cycle. The intermediate cycle is provided to transport energy from the reactor installation to the process installation requiring a high temperature heat. The distance between reactor and the process installation is assumed short and negligable, or alternatively equal to 1 km in the analysis. The system is also equipped with a high temperature argon heat pump to obtain the temperature level of a heat carrier required by a high temperature process. Thus, the steam of the intermediate cycle supplies a lower heat exchanger of the heat pump, a process heat exchanger at the medium temperature level and a classical steam turbine system (Rankine cycle. The main purpose of the research was to evaluate the effectiveness of the system considered and to assess whether such a three cycle cogeneration system is reasonable. Multivariant calculations have been carried out employing the developed mathematical model. The results have been presented in a form of the energy efficiency and exergy efficiency of the system as a function of the temperature drop in the high temperature process heat exchanger and the reactor pressure.

  17. Treating Fibrous Insulation to Reduce Thermal Conductivity

    Science.gov (United States)

    Zinn, Alfred; Tarkanian, Ryan

    2009-01-01

    A chemical treatment reduces the convective and radiative contributions to the effective thermal conductivity of porous fibrous thermal-insulation tile. The net effect of the treatment is to coat the surfaces of fibers with a mixture of transition-metal oxides (TMOs) without filling the pores. The TMO coats reduce the cross-sectional areas available for convection while absorbing and scattering thermal radiation in the pores, thereby rendering the tile largely opaque to thermal radiation. The treatment involves a sol-gel process: A solution containing a mixture of transition-metal-oxide-precursor salts plus a gelling agent (e.g., tetraethylorthosilicate) is partially cured, then, before it visibly gels, is used to impregnate the tile. The solution in the tile is gelled, then dried, and then the tile is fired to convert the precursor salts to the desired mixed TMO phases. The amounts of the various TMOs ultimately incorporated into the tile can be tailored via the concentrations of salts in the solution, and the impregnation depth can be tailored via the viscosity of the solution and/or the volume of the solution relative to that of the tile. The amounts of the TMOs determine the absorption and scattering spectra.

  18. Thermal expansion studies on Inconel-600[reg] by high temperature X-ray diffraction

    International Nuclear Information System (INIS)

    Raju, S.; Sivasubramanian, K.; Divakar, R.; Panneerselvam, G.; Banerjee, A.; Mohandas, E.; Antony, M.P.

    2004-01-01

    The lattice thermal expansion characteristics of Inconel-600[reg] have been studied by high temperature X-ray diffraction (HT-XRD) technique in the temperature range 298-1200 K. Altogether four experimental runs were conducted on thin foils of about 75-100 μm thickness. The diffraction profiles have been accurately calibrated to offset the shift in 2θ values introduced by sample buckling at elevated temperatures. The corrected lattice parameter data have been used to estimate the instantaneous and mean linear thermal expansion coefficients as a function of temperature. The thermal expansion values estimated in the present study show a fair degree of agreement with other existing dilatometer based bulk thermal expansion estimates. The lattice parameter for this alloy at 300 K is found to be 0.3549(1) nm. The mean linear thermal expansivity is found to be 11.4 x 10 -6 K -1

  19. Thermal diffusivity measurements of liquid materials at high temperature with the ''laser flash'' method

    International Nuclear Information System (INIS)

    Otter, Claude; Vandevelde, Jean

    1982-01-01

    Two solutions, one analytical and the other numerical are proposed to solve the thermokinetic problem encountered when measuring the thermal diffusivity of liquid materials at very high temperature (T>3123K). The liquid material is contained in a parallel faced vessel. This liquid is traversed by a short thermal pulse from a relaxed laser. The temperature response of the back face of the measurement cell is analysed. The first model proposed which does not take thermal losses into consideration, is a mathematical model derived from the ''two layer model'' (Larson and Koyama, 1968) extended to ''three layers''. In order to take the possibility of thermal losses to the external environment at high temperature into consideration, a Crank-Nicolson (1947) type numerical model utilizing finite differences is employed. These thermokinetic studies were performed in order to interpret temperature response curves obtained from the back face of a tungsten-liquid UO 2 -tungsten thermal wall, the purpose of the measurements made being to determine the thermal properties of liquid uranium oxide [fr

  20. High temperature annealing effects on deep-level defects in a high purity semi-insulating 4H-SiC substrate

    Energy Technology Data Exchange (ETDEWEB)

    Iwamoto, Naoya, E-mail: naoya.iwamoto@smn.uio.no; Azarov, Alexander; Svensson, Bengt G. [Department of Physics, Center for Materials Science and Nanotechnology, University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway); Ohshima, Takeshi [Japan Atomic Energy Agency, 1233 Watanuki, Takasaki, 370-1292 Gunma (Japan); Moe, Anne Marie M. [Washington Mills AS, N-7300 Orkanger (Norway)

    2015-07-28

    Effects of high-temperature annealing on deep-level defects in a high-purity semi-insulating 4H silicon carbide substrate have been studied by employing current-voltage, capacitance-voltage, junction spectroscopy, and chemical impurity analysis measurements. Secondary ion mass spectrometry data reveal that the substrate contains boron with concentration in the mid 10{sup 15 }cm{sup −3} range, while other impurities including nitrogen, aluminum, titanium, vanadium and chromium are below their detection limits (typically ∼10{sup 14 }cm{sup −3}). Schottky barrier diodes fabricated on substrates annealed at 1400–1700 °C exhibit metal/p-type semiconductor behavior with a current rectification of up to 8 orders of magnitude at bias voltages of ±3 V. With increasing annealing temperature, the series resistance of the Schottky barrier diodes decreases, and the net acceptor concentration in the substrates increases approaching the chemical boron content. Admittance spectroscopy results unveil the presence of shallow boron acceptors and deep-level defects with levels in lower half of the bandgap. After the 1400 °C annealing, the boron acceptor still remains strongly compensated at room temperature by deep donor-like levels located close to mid-gap. However, the latter decrease in concentration with increasing annealing temperature and after 1700 °C, the boron acceptor is essentially uncompensated. Hence, the deep donors are decisive for the semi-insulating properties of the substrates, and their thermal evolution limits the thermal budget for device processing. The origin of the deep donors is not well-established, but substantial evidence supporting an assignment to carbon vacancies is presented.

  1. Vibration damage testing of thermal barrier fibrous blanket insulation

    International Nuclear Information System (INIS)

    Black, W.E.; Betts, W.S.

    1984-01-01

    GA Technologies is engaged in a long-term, multiphase program to determine the vibration characteristics of thermal barrier components leading to qualification of assemblies for High Temperature Gas-Cooled Reactor (HTGR) service. The phase of primary emphasis described herein is the third in a series of acoustic tests and uses as background the more elemental tests preceding it. Two sizes of thermal barrier coverplates with one fibrous blanket insulation type were tested in an acoustic environment at sound pressure levels up to 160 dB. Three tests were conducted using sinusoidal and random noise for up to 200 h duration at room temperature. Frequent inspections were made to determine the progression of degradation using definition of stages from a prior test program. Initially the insulation surface adjacent to the metallic seal sheets (noise side) assumed a chafed or polished appearance. This was followed by flattening of the as-received pillowed surface. This stage was followed by a depression being formed in the vicinity of the free edge of the coverplate. Next, loose powder from within the blanket and from fiber erosion accumulated in the depression. Prior experience showed that the next stage of deterioration exhibited a consolidation of the powder to form a local crust. In this test series, this last stage generally failed to materialize. Instead, surface holes generated by solid ceramic particulates (commonly referred to as 'shot') constituted the stage following powdering. With the exception of some manufacturing-induced anomalies, the final stage, namely, gross fiber breakup, did not occur. It is this last stage that must be prevented for the thermal barrier to maintain its integrity. (orig./GL)

  2. Sprayable Thermal Insulation for Cryogenic Tanks, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — The Sprayable Thermal Insulation for Cryogenic Tanks (STICT) is a thermal management system applied by either an automated or manual spraying process with less...

  3. AC Losses and Their Thermal Effect in High Temperature Superconducting Machines

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan

    2015-01-01

    In transient operations or fault conditions, high temperature superconducting (HTS) machines suffer AC losses which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate AC losses and their thermal effect in HTS machines is presented....... The method consists of three sub-models that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an AC loss model which has...

  4. High-Temperature Air-Cooled Power Electronics Thermal Design: Annual Progress Report

    Energy Technology Data Exchange (ETDEWEB)

    Waye, Scot [National Renewable Energy Lab. (NREL), Golden, CO (United States)

    2016-08-01

    Power electronics that use high-temperature devices pose a challenge for thermal management. With the devices running at higher temperatures and having a smaller footprint, the heat fluxes increase from previous power electronic designs. This project overview presents an approach to examine and design thermal management strategies through cooling technologies to keep devices within temperature limits, dissipate the heat generated by the devices and protect electrical interconnects and other components for inverter, converter, and charger applications. This analysis, validation, and demonstration intends to take a multi-scale approach over the device, module, and system levels to reduce size, weight, and cost.

  5. Thermal Cycling and High Temperature Reverse Bias Testing of Control and Irradiated Gallium Nitride Power Transistors

    Science.gov (United States)

    Patterson, Richard L.; Boomer, Kristen T.; Scheick, Leif; Lauenstein, Jean-Marie; Casey, Megan; Hammoud, Ahmad

    2014-01-01

    The power systems for use in NASA space missions must work reliably under harsh conditions including radiation, thermal cycling, and exposure to extreme temperatures. Gallium nitride semiconductors show great promise, but information pertaining to their performance is scarce. Gallium nitride N-channel enhancement-mode field effect transistors made by EPC Corporation in a 2nd generation of manufacturing were exposed to radiation followed by long-term thermal cycling and testing under high temperature reverse bias conditions in order to address their reliability for use in space missions. Result of the experimental work are presented and discussed.

  6. Thermal stability of multilayered Pt-Al2O3 nanocoatings for high temperature CSP systems

    CSIR Research Space (South Africa)

    Nuru, ZY

    2015-10-01

    Full Text Available B), 115-120 Thermal stability of multilayered Pt-Al2O3 nanocoatings for high temperature CSP systems Z.Y. Nuru a, b, *, L. Kotsedi a, b, C.J. Arendse c, D. Motaung d, B. Mwakikunga d, K. Roro d, e, M. Maaza a, b a UNESCO-UNISA Africa Chair... Pretoria, South Africa e R&D Core-Energy, Council for Scientific and Industrial Research, P O Box 395, 0001 Pretoria, South Africa Abstract This contribution reports on the effect of thermal annealing on sputtered Pt–Al(sub2)O(sub3) multilayered...

  7. CFC alternatives for thermal insulation foams

    Energy Technology Data Exchange (ETDEWEB)

    Shankland, I.R. (Allied-Signal Inc., Buffalo, NY (US))

    1990-03-01

    Low density polymeric foam materials expanded with chlorofluorocarbon (CFC) blowing agents have found widespread use as highly efficient thermal insulation materials in the construction, refrigeration appliance and transportation industries. The advent of regulations which are reducing the production and consumption of the fully halogenated CFCs for environmental reasons has prompted the development of environmentally acceptable substitutes for the CFC blowing agents. This paper summarizes the physical properties and performance of the leading alternatives for CFC-11, which is used to expand rigid polyurethane and polyisocyanurate foams, and the leading alternatives for CFC-12 which is used to expand extruded polystyrene board foam. Although the alternatives, HCFC-123 and HCFC-14lb for CFC-11 and HCFC142b and HCFC-124 for CFC-12, are not perfect matches from the performance viewpoint, they represent the optimum choice given the constraints on environmental acceptability, toxicity, flammability and performance. (author).

  8. Synthesis and thermal properties of a novel high temperature alkyl-center-trisphenolic-based phthalonitrile polymer

    International Nuclear Information System (INIS)

    Sheng, Haitong; Peng, Xuegang; Guo, Hui; Yu, Xiaoyan; Tang, Chengchun; Qu, Xiongwei; Zhang, Qingxin

    2013-01-01

    A novel alkyl-center-trisphenolic-based high-temperature phthalonitrile monomer, namely, 1,1,1-tris-[4-(3,4-dicyanophenoxy)phenyl]ethane (TDPE), was synthesized from 1,1,1-tris-(4-hydroxyphenyl)ethane (THPE) via a facile nucleophilic displacement of a nitro-substituent from 4-nitrophthalonitrile (NPN). The structure of TDPE monomer was characterized by Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance spectroscopy ( 1 H and 13 C NMR), elemental analysis (EA). Curing behaviors of TDPE with 4-(aminophenoxy)phthalonitrile (APPH) were recorded by differential scanning calorimetric (DSC) and it showed a large processing window (122 °C) which is favorable to processing TDPE polymers. The structure of TDPE polymer was discussed and the thermal stabilities of TDPE polymer were evaluated by thermogravimetric analysis (TGA). The TDPE polymer exhibits excellent thermal stability, and mechanism of thermal decompositions was explored. Dynamic mechanical analysis (DMA) revealed that the TDPE polymer has high storage modulus and high glass transition temperature (T g > 380 °C). - Highlights: • A novel high-temperature phthalonitrile polymer was synthesized. • Polymerization mechanism was explored. • The polymer shows excellent thermal stability. • Outstanding mechanical properties was achieved: storage modulus = 3.7 GPa, T g > 380 °C. • Thermal decomposition mechanism was discussed

  9. High-Temperature Thermal Energy Storage for electrification and district heating

    DEFF Research Database (Denmark)

    Pedersen, A. Schrøder; Engelbrecht, K.; Soprani, S.

    stability upon thermal cycling. The most promising material consists of basalt, diabase, and magnetite, whereas the less suited rocks contain larger proportions of quartz and mica. An HT-TES system, containing 1.5 m3 of rock pieces, was constructed. The rock bed was heated to 600 ˚C using an electric heater......The present work describes development of a High Temperature Thermal Energy Storage (HT-TES) system based on rock bed technology. A selection of rocks was investigated by thermal analysis in the range 20-800 ˚C. Subsequently, a shortlist was defined primarily based on mechanical and chemical...... to simulate thermal charging from wind energy. After complete heating of the rock bed it was left fully charged for hours to simulate actual storage conditions. Subsequently the bed discharging was performed by leading cold air through the rock bed whereby the air was heated and led to an exhaust. The results...

  10. An extended laser flash technique for thermal diffusivity measurement of high-temperature materials

    Science.gov (United States)

    Shen, F.; Khodadadi, J. M.

    1993-01-01

    Knowledge of thermal diffusivity data for high-temperature materials (solids and liquids) is very important in analyzing a number of processes, among them solidification, crystal growth, and welding. However, reliable thermal diffusivity versus temperature data, particularly those for high-temperature liquids, are still far from complete. The main measurement difficulties are due to the presence of convection and the requirement for a container. Fortunately, the availability of levitation techniques has made it possible to solve the containment problem. Based on the feasibility of the levitation technology, a new laser flash technique which is applicable to both levitated liquid and solid samples is being developed. At this point, the analysis for solid samples is near completion and highlights of the technique are presented here. The levitated solid sample which is assumed to be a sphere is subjected to a very short burst of high power radiant energy. The temperature of the irradiated surface area is elevated and a transient heat transfer process takes place within the sample. This containerless process is a two-dimensional unsteady heat conduction problem. Due to the nonlinearity of the radiative plus convective boundary condition, an analytic solution cannot be obtained. Two options are available at this point. Firstly, the radiation boundary condition can be linearized, which then accommodates a closed-form analytic solution. Comparison of the analytic curves for the temperature rise at different points to the experimentally-measured values will then provide the thermal diffusivity values. Secondly, one may set up an inverse conduction problem whereby experimentally obtained surface temperature history is used as the boundary conditions. The thermal diffusivity can then be elevated by minimizing the difference between the real heat flux boundary condition (radiation plus convection) and the measurements. Status of an experimental study directed at measuring the

  11. Electromagnetic Acoustic Transducers Applied to High Temperature Plates for Potential Use in the Solar Thermal Industry

    Directory of Open Access Journals (Sweden)

    Maria Kogia

    2015-12-01

    Full Text Available Concentrated Solar Plants (CSPs are used in solar thermal industry for collecting and converting sunlight into electricity. Parabolic trough CSPs are the most widely used type of CSP and an absorber tube is an essential part of them. The hostile operating environment of the absorber tubes, such as high temperatures (400–550 °C, contraction/expansion, and vibrations, may lead them to suffer from creep, thermo-mechanical fatigue, and hot corrosion. Hence, their condition monitoring is of crucial importance and a very challenging task as well. Electromagnetic Acoustic Transducers (EMATs are a promising, non-contact technology of transducers that has the potential to be used for the inspection of large structures at high temperatures by exciting Guided Waves. In this paper, a study regarding the potential use of EMATs in this application and their performance at high temperature is presented. A Periodic Permanent Magnet (PPM EMAT with a racetrack coil, designed to excite Shear Horizontal waves (SH0, has been theoretically and experimentally evaluated at both room and high temperatures.

  12. An assessment of thermal spray coating technologies for high temperature corrosion protection

    International Nuclear Information System (INIS)

    Heath, G.R.; Heimgartner, P.; Gustafsson, S.; Irons, G.; Miller, R.

    1997-01-01

    The use of thermally sprayed coatings in combating high temperature corrosion continues to grow in the major industries of chemical, waste incineration, power generation and pulp and paper. This has been driven partially by the development of corrosion resistant alloys, improved knowledge and quality in the thermal spray industry and continued innovation in thermal spray equipment. There exists today an extensive range of thermal spray process options, often with the same alloy solution. In demanding corrosion applications it is not sufficient to just specify alloy and coating method. For the production of reliable coatings the whole coating production envelope needs to be considered, including alloy selection, spray parameters, surface preparation, base metal properties, heat input etc. Combustion, arc-wire, plasma, HVOF and spray+fuse techniques are reviewed and compared in terms of their strengths and limitations to provide cost-effective solutions for high temperature corrosion protection. Arc wire spraying, HP/HVOF and spray+fuse are emerging as the most promising techniques to optimise both coating properties and economic/practical aspects. (orig.)

  13. Dimethyl terephthalate (DMT) as a candidate phase change material for high temperature thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Kuecuekaltun, Engin [Advansa Sasa Polyester San, A.S., Adana (Turkey); Paksoy, Halime; Bilgin, Ramazan; Yuecebilgic, Guezide [Cukurova Univ., Adana (Turkey). Chemistry Dept.; Evliya, Hunay [Cukurova Univ., Adana (Turkey). Center for Environmental Research

    2010-07-01

    Thermal energy storage at elevated temperatures, particularly in the range of 120-250 C is of interest with a significant potential for industrial applications that use process steam at low or intermediate pressures. At given temperature range there are few studies on thermal energy storage materials and most of them are dedicated to sensible heat. In this study, Dimethyl Terephthalate - DMT (CAS No: 120-61-6) is investigated as a candidate phase change material (PCM) for high temperature thermal energy storage. DMT is a monomer commonly used in Polyethylene terephtalate industry and has reasonable cost and availability. The Differential Scanning Calorimetry (DSC) analysis and heating cooling curves show that DMT melts at 140-146 C within a narrow window. Supercooling that was detected in DSC results was not observed in the cooling curve measurements made with a larger sample. With a latent heat of 193 J/g, DMT is a candidate PCM for high temperature storage. Potential limitations such as, low thermal conductivity and sublimation needs further investigation. (orig.)

  14. CFX-10 Analysis of the High Temperature Thermal- Chemical Experiment (CS28-2)

    International Nuclear Information System (INIS)

    Kim, Hyoung Tae; Park, Joo Hwan; Rhee, Bo Wook

    2008-02-01

    A Computational Fluid Dynamics (CFD) model of a post-blowdown fuel channel analysis for aged CANDU reactors with crept pressure tube has been developed, and validated against a high temperature thermal-chemical experiment: CS28-2. The CS28-2 experiment is one of three series of experiments to simulate the thermal-chemical behavior of a 28-element fuel channel at a high temperature and a low steam flow rate which may occur in severe accident conditions such as a LBLOCA (Large Break Loss of Coolant Accident) of CANDU reactors. Pursuant to the objective of this study, the current study has focused on understanding the involved phenomena such as the thermal radiation and convection heat transfer, and the high temperature zirconium-steam reaction in a multi-ring geometry. Therefore, a zirconium-steam oxidation model based on a parabolic rate law was implemented into the CFX-10 code, which is a commercial CFD code offered from ANSYS Inc., and other heat transfer mechanisms in the 28-element fuel channel were modeled by the original CFX-10 heat transfer packages. To assess the capability of the CFX-10 code to model the thermal-chemical behavior of the 28-element fuel channel, the measured temperatures of the Fuel Element Simulators (FES) of three fuel rings in the test bundle and the pressure tube, and the hydrogen production in the CS28-2 experiment were compared with the CFX-10 predictions. In spite of some discrepancy between the measurement data and CFX results, it was found that the CFX-10 prediction based on the Urbanic-Heidrick correlation of the zirconium-steam reaction as well as the Discrete Transfer Model for a radiation heat transfer among the FES of three rings and the pressure tube are quite accurate and sound even for the offset a cluster fuel bundle of an aged fuel channel

  15. CFX-10 Analysis of the High Temperature Thermal- Chemical Experiment (CS28-2)

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hyoung Tae; Park, Joo Hwan; Rhee, Bo Wook

    2008-02-15

    A Computational Fluid Dynamics (CFD) model of a post-blowdown fuel channel analysis for aged CANDU reactors with crept pressure tube has been developed, and validated against a high temperature thermal-chemical experiment: CS28-2. The CS28-2 experiment is one of three series of experiments to simulate the thermal-chemical behavior of a 28-element fuel channel at a high temperature and a low steam flow rate which may occur in severe accident conditions such as a LBLOCA (Large Break Loss of Coolant Accident) of CANDU reactors. Pursuant to the objective of this study, the current study has focused on understanding the involved phenomena such as the thermal radiation and convection heat transfer, and the high temperature zirconium-steam reaction in a multi-ring geometry. Therefore, a zirconium-steam oxidation model based on a parabolic rate law was implemented into the CFX-10 code, which is a commercial CFD code offered from ANSYS Inc., and other heat transfer mechanisms in the 28-element fuel channel were modeled by the original CFX-10 heat transfer packages. To assess the capability of the CFX-10 code to model the thermal-chemical behavior of the 28-element fuel channel, the measured temperatures of the Fuel Element Simulators (FES) of three fuel rings in the test bundle and the pressure tube, and the hydrogen production in the CS28-2 experiment were compared with the CFX-10 predictions. In spite of some discrepancy between the measurement data and CFX results, it was found that the CFX-10 prediction based on the Urbanic-Heidrick correlation of the zirconium-steam reaction as well as the Discrete Transfer Model for a radiation heat transfer among the FES of three rings and the pressure tube are quite accurate and sound even for the offset a cluster fuel bundle of an aged fuel channel.

  16. Analytical method for estimating the thermal expansion coefficient of metals at high temperature

    International Nuclear Information System (INIS)

    Takamoto, S; Izumi, S; Nakata, T; Sakai, S; Oinuma, S; Nakatani, Y

    2015-01-01

    In this paper, we propose an analytical method for estimating the thermal expansion coefficient (TEC) of metals at high-temperature ranges. Although the conventional method based on quasiharmonic approximation (QHA) shows good results at low temperatures, anharmonic effects caused by large-amplitude thermal vibrations reduces its accuracy at high temperatures. Molecular dynamics (MD) naturally includes the anharmonic effect. However, since the computational cost of MD is relatively high, in order to make an interatomic potential capable of reproducing TEC, an analytical method is essential. In our method, analytical formulation of the radial distribution function (RDF) at finite temperature realizes the estimation of the TEC. Each peak of the RDF is approximated by the Gaussian distribution. The average and variance of the Gaussian distribution are formulated by decomposing the fluctuation of interatomic distance into independent elastic waves. We incorporated two significant anharmonic effects into the method. One is the increase in the averaged interatomic distance caused by large amplitude vibration. The second is the variation in the frequency of elastic waves. As a result, the TECs of fcc and bcc crystals estimated by our method show good agreement with those of MD. Our method enables us to make an interatomic potential that reproduces the TEC at high temperature. We developed the GEAM potential for nickel. The TEC of the fitted potential showed good agreement with experimental data from room temperature to 1000 K. As compared with the original potential, it was found that the third derivative of the wide-range curve was modified, while the zeroth, first and second derivatives were unchanged. This result supports the conventional theory of solid state physics. We believe our analytical method and developed interatomic potential will contribute to future high-temperature material development. (paper)

  17. The design of high-temperature thermal conductivity measurements apparatus for thin sample size

    Directory of Open Access Journals (Sweden)

    Hadi Syamsul

    2017-01-01

    Full Text Available This study presents the designing, constructing and validating processes of thermal conductivity apparatus using steady-state heat-transfer techniques with the capability of testing a material at high temperatures. This design is an improvement from ASTM D5470 standard where meter-bars with the equal cross-sectional area were used to extrapolate surface temperature and measure heat transfer across a sample. There were two meter-bars in apparatus where each was placed three thermocouples. This Apparatus using a heater with a power of 1,000 watts, and cooling water to stable condition. The pressure applied was 3.4 MPa at the cross-sectional area of 113.09 mm2 meter-bar and thermal grease to minimized interfacial thermal contact resistance. To determine the performance, the validating process proceeded by comparing the results with thermal conductivity obtained by THB 500 made by LINSEIS. The tests showed the thermal conductivity of the stainless steel and bronze are 15.28 Wm-1K-1 and 38.01 Wm-1K-1 with a difference of test apparatus THB 500 are −2.55% and 2.49%. Furthermore, this apparatus has the capability to measure the thermal conductivity of the material to a temperature of 400°C where the results for the thermal conductivity of stainless steel is 19.21 Wm-1K-1 and the difference was 7.93%.

  18. High sensitivity thermal sensors on insulating diamond

    Energy Technology Data Exchange (ETDEWEB)

    Job, R. [Fernuniversitaet Hagen (Gesamthochschule) (Germany). Electron. Devices; Denisenko, A.V. [Fernuniversitaet Hagen (Gesamthochschule) (Germany). Electron. Devices; Zaitsev, A.M. [Fernuniversitaet Hagen (Gesamthochschule) (Germany). Electron. Devices; Melnikov, A.A. [Belarussian State Univ., Minsk (Belarus). HEII and FD; Werner, M. [VDI/VDE-IT, Teltow (Germany); Fahrner, W.R. [Fernuniversitaet Hagen (Gesamthochschule) (Germany). Electron. Devices

    1996-12-15

    Diamond is a promising material to develop sensors for applications in harsh environments. To increase the sensitivity of diamond temperature sensors the effect of thermionic hole emission (TE) over an energetic barrier formed in the interface between highly boron-doped p-type and intrinsic insulating diamond areas has been suggested. To study the TE of holes a p-i-p diode has been fabricated and analyzed by electrical measurements in the temperature range between 300 K and 700 K. The experimental results have been compared with numerical simulations of its electrical characteristics. Based on a model of the thermionic emission of carriers into an insulator it has been suggested that the temperature sensitivity of the p-i-p diode on diamond is strongly affected by the re-emission of holes from a group of donor-like traps located at a level of 0.7-1.0 eV above the valence band. The mechanism of thermal activation of the current includes a spatial redistribution of the potential, which results in the TE regime from a decrease of the immobilized charge of the ionized traps within the i-zone of the diode and the correspondent lowering of the forward biased barrier. The characteristics of the p-i-p diode were studied with regard to temperature sensor applications. The temperature coefficient of resistance (TCR=-0.05 K{sup -1}) for temperatures above 600 K is about four times larger than the maximal attainable TCR for conventional boron-doped diamond resistors. (orig.)

  19. Environmental safety providing during heat insulation works and using thermal insulation materials

    Directory of Open Access Journals (Sweden)

    Velichko Evgeny

    2017-01-01

    Full Text Available This article considers the negative effect of thermal insulating materials and products on human health and environment pollution, particularly in terms of the composition of environmentally hazardous construction products. The authors have analyzed the complex measures for providing ecological safety, sanitary and epidemiological requirements, rules and regulations both during thermal insulation works and throughout the following operation of buildings and premises. The article suggests the protective and preventive measures to reduce and eliminate the negative impact of the proceeding of thermal insulation works on the natural environment and on human health.

  20. High temperature thermal storage for solar gas turbines using encapsulated phase change materials

    CSIR Research Space (South Africa)

    Klein, P

    2014-01-01

    Full Text Available in the near term. Sensible heat storage in packed beds involves a random packing of ceramic pebbles/particles in an insulated container. The temperature change of the solid during charging/discharging is used to store/release thermal energy. The primary... the packed bed due to vaporization and condensation effects. 2.3. Macro-encapsulation of PCM In the macro-encapsulation approach the PCM is retained within a hollow shell material. The shell can be preformed, filled with a molten PCM and sealed; or it can...

  1. Thermally activated flux creep in strongly layered high-temperature superconductors

    International Nuclear Information System (INIS)

    Chakravarty, S.; Ivlev, B.I.; Ovchinnikov, Y.N.

    1990-01-01

    Thermal activation energies for single vortices and vortex bundles in the presence of a magnetic field parallel to the layers are calculated. The pinning considered is intrinsic and is due to the strongly layered structure of high-temperature superconductors. The magnetic field and the current dependence of the activation energy are studied in detail. The calculation of the activation energy is used to determine the current-voltage characteristic. It may be possible to observe the effects discussed in this paper in a pure enough sample

  2. INSUL, Calculation of Thermal Insulation of Various Materials Immersed in He

    International Nuclear Information System (INIS)

    Kinkead, A.N.; Pitchford, B.E.

    1977-01-01

    1 - Nature of the physical problem solved: Performance of thermal insulation immersed in helium. 2 - Method of solution: Mineral fibre, metal fibre and metallic multi-layer foils are studied. An approximate analysis for performance evaluation of multi-layer insulation in vertical gas spaces including the regime between fully suppressed natural convection and that for which an accepted power relationship applies is included

  3. An experimental study on thermal properties of composite insulation

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Gyoung-Seok [Building and Urban Research Department, Korea Institute of Construction Technology, 2311 Daehwa-Dong, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 411-712 (Korea); College of Architecture, Hanyang University, 17, Hangdang-Dong, Sungdong-Gu, Seoul 133-791 (Korea); Kang, Jae-Sik; Jeong, Young-Sun; Lee, Seung-Eon [Building and Urban Research Department, Korea Institute of Construction Technology, 2311 Daehwa-Dong, Ilsanseo-Gu, Goyang-Si, Gyeonggi-Do 411-712 (Korea); Sohn, Jang-Yeul [College of Architecture, Hanyang University, 17, Hangdang-Dong, Sungdong-Gu, Seoul 133-791 (Korea)

    2007-04-01

    In accordance with the insulation standards reinforced since 2001 and the compulsory standards on floor impact sound insulation that have been enforced since 2004, insulation materials for actual buildings have been converted to composite materials and new insulation materials have been released in the market. However, Korea is lagging behind the world in fundamental experimental studies and resources. In case of some composite insulation materials, there also have been problems of distorted performance occurring as a result of tests being conducted without having verification and evaluation on the accuracy and inaccuracy of such tests. Therefore, this study grasped the thermal properties of composite insulation materials using thermal conductivity test equipment by heat flux method, and performed quantitative evaluation on the measurement precision and uncertainty of composite materials. (author)

  4. The Wick-Concept for Thermal Insulation of Cold Piping

    DEFF Research Database (Denmark)

    Koverdynsky, Vit; Korsgaard, Vagn; Rode, Carsten

    2006-01-01

    the wick-concept in either of two variations: the self-drying or the self-sealing system. Experiments have been carried out using different variations of the two systems to investigate the conditions for exploiting the drying capabilities of the systems, and the results are presented. The results show......The wick-concept for thermal insulation of cold piping is based on capillary suction of a fiber fabric to remove excess water from the pipe surface by transporting it to the outer surface of the insulation. From the surface of the insulation jacket, the water will evaporate to the ambient air....... This will prevent long-term accumulation of moisture in the insulation material. The wick keeps the hydrophobic insulation dry, allowing it to maintain its thermal performance. The liquid moisture is kept only in the wick fabric. This article presents the principle of operation of cold pipe insulation using...

  5. Polyimide-Foam/Aerogel Composites for Thermal Insulation

    Science.gov (United States)

    Williams, Martha; Fesmire, James; Sass, Jared; Smith, Trent; Weoser. Erol

    2009-01-01

    Composites of specific types of polymer foams and aerogel particles or blankets have been proposed to obtain thermal insulation performance superior to those of the neat polyimide foams. These composites have potential to also provide enhanced properties for vibration dampening or acoustic attenuation. The specific type of polymer foam is denoted "TEEK-H", signifying a series, denoted H, within a family of polyimide foams that were developed at NASA s Langley Research Center and are collectively denoted TEEK (an acronym of the inventors names). The specific types of aerogels include Nanogel aerogel particles from Cabot Corporation in Billerica, MA. and of Spaceloft aerogel blanket from Aspen Aerogels in Northborough, MA. The composites are inherently flame-retardant and exceptionally thermally stable. There are numerous potential uses for these composites, at temperatures from cryogenic to high temperatures, in diverse applications that include aerospace vehicles, aircraft, ocean vessels, buildings, and industrial process equipment. Some low-temperature applications, for example, include cryogenic storage and transfer or the transport of foods, medicines, and chemicals. Because of thermal cycling, aging, and weathering most polymer foams do not perform well at cryogenic temperatures and will undergo further cracking over time. The TEEK polyimides are among the few exceptions to this pattern, and the proposed composites are intended to have all the desirable properties of TEEK-H foams, plus improved thermal performance along with enhanced vibration or acoustic-attenuation performance. A composite panel as proposed would be fabricated by adding an appropriate amount of TEEK friable balloons into a mold to form a bottom layer. A piece of flexible aerogel blanket material, cut to the desired size and shape, would then be placed on the bottom TEEK layer and sandwiched between another top layer of polyimide friable balloons so that the aerogel blanket would become

  6. Estimation of thermal insulation performance in multi-layer insulator for liquid helium pipe

    International Nuclear Information System (INIS)

    Shibanuma, Kiyoshi; Kuriyama, Masaaki; Shibata, Takemasa

    1991-01-01

    For a multi-layer insulator around the liquid helium pipes for cryopumps of JT-60 NBI, a multi-layer insulator composed of 10 layers, which can be wound around the pipe at the same time and in which the respective layers are in concentric circles by shifting them in arrangement, has been developed and tested. As the result, it was shown that the newly developed multi-layer insulator has better thermal insulation performance than the existing one, i.e. the heat load of the newly developed insulator composed of 10 layers was reduced to 1/3 the heat load of the existing insulator, and the heat leak at the joint of the insulator in longitudinal direction of the pipe was negligible. In order to clarify thermal characteristics of the multi-layer insulator, the heat transfer through the insulator has been analyzed considering the radiation heat transfer by the netting spacer between the reflectors, and the temperature dependence on the emissivities and the heat transmission coefficients of these two components of the insulator. The analytical results were in good agreements with the experimental ones, so that the analytical method was shown to be valid. Concerning the influence of the number of layers and the layer density on the insulation performance of the insulator, analytical results showed that the multi-layer insulator with the number of layer about N = 20 and the layer density below 2.0 layer/mm was the most effective for the liquid helium pipe of a JT-60 cryopump. (author)

  7. Evaluation of high temperature superconductive thermal bridges for space borne cryogenic detectors

    Science.gov (United States)

    Scott, Elaine P.

    1996-01-01

    Infrared sensor satellites are used to monitor the conditions in the earth's upper atmosphere. In these systems, the electronic links connecting the cryogenically cooled infrared detectors to the significantly warmer amplification electronics act as thermal bridges and, consequently, the mission lifetimes of the satellites are limited due to cryogenic evaporation. High-temperature superconductor (HTS) materials have been proposed by researchers at the National Aeronautics and Space Administration Langley's Research Center (NASA-LaRC) as an alternative to the currently used manganin wires for electrical connection. The potential for using HTS films as thermal bridges has provided the motivation for the design and the analysis of a spaceflight experiment to evaluate the performance of this superconductive technology in the space environment. The initial efforts were focused on the preliminary design of the experimental system which allows for the quantitative comparison of superconductive leads with manganin leads, and on the thermal conduction modeling of the proposed system. Most of the HTS materials were indicated to be potential replacements for the manganin wires. In the continuation of this multi-year research, the objectives of this study were to evaluate the sources of heat transfer on the thermal bridges that have been neglected in the preliminary conductive model and then to develop a methodology for the estimation of the thermal conductivities of the HTS thermal bridges in space. The Joule heating created by the electrical current through the manganin wires was incorporated as a volumetric heat source into the manganin conductive model. The radiative heat source on the HTS thermal bridges was determined by performing a separate radiant interchange analysis within a high-T(sub c) superconductor housing area. Both heat sources indicated no significant contribution on the cryogenic heat load, which validates the results obtained in the preliminary conduction

  8. Positron annihilation in Si and Si-related materials in thermal equilibrium at high temperature

    International Nuclear Information System (INIS)

    Uedono, A.; Muramatsu, M.; Ubukata, T.; Tanino, H.; Shiraishi, T.; Tanigawa, S.; Takasu, S.

    2001-01-01

    Annihilation characteristics of positrons in the carbon/Si structure in thermal equilibrium at high temperature were studied using a monoenergetic positron beam. Doppler broadening spectra of the annihilation radiation were measured as a function of incident positron energy in the temperature range between 298 K and 1473 K. Above 1173 K, the value of S corresponding to the annihilation of positrons near the carbon/Si interface started to increase, which was attributed to the carbonization of Si and the introduction of open-space defects due to the diffusion of Si atoms toward the carbon layer. The behavior of Ps in a thermally grown SiO 2 film was also studied at 298-1523 K. (orig.)

  9. Experimental investigation of linear thermal expansion of pyrolytic graphite at high temperatures

    Science.gov (United States)

    Senchenko, V. N.; Belikov, R. S.

    2017-11-01

    Using the previously described [1] experimental setup for investigation of the thermophysical properties of refractory materials under high pressure and temperature a few experiments with pyrolytic graphite were carried out. The density of the material was equal to 2.18 g/cm3. Experimental data on the linear thermal expansion in the perpendicular and parallel to the basal plane direction were obtained. Thermal expansion in the perpendicular to the basal plane direction during the heating from room temperature up to the melting point was 16.4 ± 1.6%. The results obtained allow calculating the density of pyrolytic graphite in the wide range of high temperatures up to the melting point.

  10. Potential for cladding thermal failure in LWRs during high temperature transients

    International Nuclear Information System (INIS)

    El Genk, M.S.

    1979-01-01

    The temperature increase in the fuel and the cladding during a PCM accident produces film boiling at the cladding surface which may induce zircaloy cladding failure, due to embrittlement, and fuel melting at the centerline of the fuel pellets. Molten fuel may extrude through radial cracks in the fuel and relocate in the fuel-cladding gap. Contact of extruded molten fuel with the cladding, which is at high temperature during film boiling, may induce cladding thermal failure due to melting. An assessment of central fuel melting and molten fuel extrusion into the fuel-cladding gap during a PCM accident is presented. The potential for thermal failure of the zircaloy cladding upon being contacted by molten fuel during such an accident is also analyzed and compared with the applicable experimental evidence

  11. Network structure and thermal stability study of high temperature seal glass

    Science.gov (United States)

    Lu, K.; Mahapatra, M. K.

    2008-10-01

    High temperature seal glass has stringent requirement on glass thermal stability, which is dictated by glass network structures. In this study, a SrO-La2O3-Al2O3-B2O3-SiO2 based glass system was studied using nuclear magnetic resonance, Raman spectroscopy, and x-ray diffraction for solid oxide cell application purpose. Glass structural unit neighboring environment and local ordering were evaluated. Glass network connectivity as well as silicon and boron glass former coordination were calculated for different B2O3:SiO2 ratios. Thermal stability of the borosilicate glasses was studied after thermal treatment at 850 °C. The study shows that high B2O3 content induces BO4 and SiO4 structural unit ordering, increases glass localized inhomogeneity, decreases glass network connectivity, and causes devitrification. Glass modifiers interact with either silicon- or boron-containing structural units and form different devitrified phases at different B2O3:SiO2 ratios. B2O3-free glass shows the best thermal stability among the studied compositions, remaining stable after thermal treatment for 200 h at 850 °C.

  12. High temperature thermal conductivity measurements of UO2 by Direct Electrical Heating. Final report

    International Nuclear Information System (INIS)

    Bassett, B.

    1980-10-01

    High temperature properties of reactor type UO 2 pellets were measured using a Direct Electrical Heating (DEH) Facility. Modifications to the experimental apparatus have been made so that successful and reproducible DEH runs may be carried out while protecting the pellets from oxidation at high temperature. X-ray diffraction measurements on the UO 2 pellets have been made before and after runs to assure that sample oxidation has not occurred. A computer code has been developed that will model the experiment using equations that describe physical properties of the material. This code allows these equations to be checked by comparing the model results to collected data. The thermal conductivity equation for UO 2 proposed by Weilbacher has been used for this analysis. By adjusting the empirical parameters in Weilbacher's equation, experimental data can be matched by the code. From the several runs analyzed, the resulting thermal conductivity equation is lambda = 1/4.79 + 0.0247T/ + 1.06 x 10 -3 exp[-1.62/kT/] - 4410. exp[-3.71/kT/] where lambda is in w/cm K, k is the Boltzman constant, and T is the temperature in Kelvin

  13. Comparative study of thermal insulation boards from leaf and bark ...

    African Journals Online (AJOL)

    Thus, several researches have succeeded in using these plants and agro waste fibres in developing renewable and environmentally friendly thermal insulation products. The aim of this study was to compare the performance of insulation boards made from leave and bark fibres of Pilios tigma thonningii L.in terms of density, ...

  14. Thermal spray coating for corrosion under insulation (CUI) prevention

    Science.gov (United States)

    Fuad, Mohd Fazril Irfan Ahmad; Razak, Khalil Abdul; Alias, Nur Hashimah; Othman, Nur Hidayati; Lah, Nik Khairul Irfan Nik Ab

    2017-12-01

    Corrosion under insulation (CUI) is one of the predominant issues affecting process of Oil and Gas and Petrochemical industries. CUI refers to external corrosion, but it is difficult to be detected as the insulation cover masks the corrosion problem. One of the options to prevent CUI is by utilizing the protective coating systems. Thermal spray coating (TSC) is an advanced coating system and it shows promising performance in harsh environment, which could be used to prevent CUI. However, the application of TSC is not attractive due to the high initial cost. This work evaluates the potential of TSC based on corrosion performance using linear polarization resistance (LPR) method and salt spray test (SST). Prior to the evaluation, the mechanical performance of TSC was first investigated using adhesion test and bend test. Microstructure characterization of the coating was investigated using Scanning Electron Microscope (SEM). The LPR test results showed that low corrosion rate of 0.05 mm/years was obtained for TSC in compared to the bare steel especially at high temperature of 80 °C, where usually normal coating would fail. For the salt spray test, there was no sign of corrosion products especially at the center (fully coated region) was observed. From SEM images, no corrosion defects were observed after 336 hours of continuous exposure to salt fog test. This indicates that TSC protected the steel satisfactorily by acting as a barrier from a corrosive environment. In conclusion, TSC can be a possible solution to minimize the CUI in a long term. Further research should be done on corrosion performance and life cycle cost by comparing TSC with other conventional coating technology.

  15. High temperature deformation behavior, thermal stability and irradiation performance in Grade 92 steel

    Science.gov (United States)

    Alsagabi, Sultan

    The 9Cr-2W ferritic-martensitic steel (i.e. Grade 92 steel) possesses excellent mechanical and thermophysical properties; therefore, it has been considered to suit more challenging applications where high temperature strength and creep-rupture properties are required. The high temperature deformation mechanism was investigated through a set of tensile testing at elevated temperatures. Hence, the threshold stress concept was applied to elucidate the operating high temperature deformation mechanism. It was identified as the high temperature climb of edge dislocations due to the particle-dislocation interactions and the appropriate constitutive equation was developed. In addition, the microstructural evolution at room and elevated temperatures was investigated. For instance, the microstructural evolution under loading was more pronounced and carbide precipitation showed more coarsening tendency. The growth of these carbide precipitates, by removing W and Mo from matrix, significantly deteriorates the solid solution strengthening. The MX type carbonitrides exhibited better coarsening resistance. To better understand the thermal microstructural stability, long tempering schedules up to 1000 hours was conducted at 560, 660 and 760°C after normalizing the steel. Still, the coarsening rate of M23C 6 carbides was higher than the MX-type particles. Moreover, the Laves phase particles were detected after tempering the steel for long periods before they dissolve back into the matrix at high temperature (i.e. 720°C). The influence of the tempering temperature and time was studied for Grade 92 steel via Hollomon-Jaffe parameter. Finally, the irradiation performance of Grade 92 steel was evaluated to examine the feasibility of its eventual reactor use. To that end, Grade 92 steel was irradiated with iron (Fe2+) ions to 10, 50 and 100 dpa at 30 and 500°C. Overall, the irradiated samples showed some irradiation-induced hardening which was more noticeable at 30°C. Additionally

  16. Sprayable Thermal Insulation for Cryogenic Tanks, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The innovation addressed in this proposal is Sprayable Thermal Insulation for Cryogenic Tanks, or STICT. This novel system could be applied in either an automated or...

  17. Model-based analysis of thermal insulation coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2014-01-01

    Thermal insulation properties of coatings based on selected functional filler materials are investigated. The underlying physics, thermal conductivity of a heterogeneous two-component coating, and porosity and thermal conductivity of hollow spheres (HS) are quantified and a mathematical model for...

  18. Extreme temperature stability of thermally insulating graphene-mesoporous-silicon nanocomposite

    Science.gov (United States)

    Kolhatkar, Gitanjali; Boucherif, Abderraouf; Rahim Boucherif, Abderrahim; Dupuy, Arthur; Fréchette, Luc G.; Arès, Richard; Ruediger, Andreas

    2018-04-01

    We demonstrate the thermal stability and thermal insulation of graphene-mesoporous-silicon nanocomposites (GPSNC). By comparing the morphology of GPSNC carbonized at 650 °C as-formed to that after annealing, we show that this nanocomposite remains stable at temperatures as high as 1050 °C due to the presence of a few monolayers of graphene coating on the pore walls. This does not only make this material compatible with most thermal processes but also suggests applications in harsh high temperature environments. The thermal conductivity of GPSNCs carbonized at temperatures in the 500 °C-800 °C range is determined through Raman spectroscopy measurements. They indicate that the thermal conductivity of the composite is lower than that of silicon, with a value of 13 ± 1 W mK-1 at room temperature, and not affected by the thin graphene layer, suggesting a role of the high concentration of carbon related-defects as indicated by the high intensity of the D-band compared to G-band of the Raman spectra. This morphological stability at high temperature combined with a high thermal insulation make GPSNC a promising candidate for a broad range of applications including microelectromechanical systems and thermal effect microsystems such as flow sensors or IR detectors. Finally, at 120 °C, the thermal conductivity remains equal to that at room temperature, attesting to the potential of using our nanocomposite in devices that operate at high temperatures such as microreactors for distributed chemical conversion, solid oxide fuel cells, thermoelectric devices or thermal micromotors.

  19. Role of high-temperature creep stress in thermally grown oxide growth of thermal barrier coatings

    Energy Technology Data Exchange (ETDEWEB)

    Ogawa, K.; Nakao, Y.; Seo, D.; Miura, H.; Shoji, T. [Tohoku Univ., Sendai (Japan)

    2008-07-01

    Thermally grown oxide (TGO) grows at the top / bond coating interface of the thermal barrier coating (TBC) in service. It is supposed that the failures of the TBC occur due to thermal stress and the decrease of adhesive strength caused by the TGO growth. Recently, large local stress has been found to change both the diffusion constant of oxygen through an existing oxide and the rate of chemical reaction at the oxide / oxidized material interface. Since high thermal stress occurs in the TBC, the volume expansion of the newly grown oxide, and centrifugal force, the growth rate of the TGO may change depending on not only temperature but also the stress. The aim of this study is to make clear the influence of stress on the growth rate of the TGO quantitatively. As a result, the thickness of the TGO clearly increases with increase of the amplitude of the applied stress and temperature. The increase rate of the TGO thickness is approximately 23% when the applied stress is increased from 0 to 205 MPa at 900 C, and approximately 29% when the stress is increased from 0 to 150 MPa at 950 C. (orig.)

  20. Thermal energy storages analysis for high temperature in air solar systems

    International Nuclear Information System (INIS)

    Andreozzi, Assunta; Buonomo, Bernardo; Manca, Oronzio; Tamburrino, Salvatore

    2014-01-01

    In this paper a high temperature thermal storage in a honeycomb solid matrix is numerically investigated and a parametric analysis is accomplished. In the formulation of the model it is assumed that the system geometry is cylindrical, the fluid and the solid thermo physical properties are temperature independent and radiative heat transfer is taken into account whereas the effect of gravity is neglected. Air is employed as working fluid and the solid material is cordierite. The evaluation of the fluid dynamic and thermal behaviors is accomplished assuming the honeycomb as a porous medium. The Brinkman–Forchheimer–extended Darcy model is used in the governing equations and the local thermal non equilibrium is assumed. The commercial CFD Fluent code is used to solve the governing equations in transient regime. Numerical simulations are carried out with storage medium for different mass flow rates of the working fluid and different porosity values. Results in terms of temperature profiles, temperatures fields and stored thermal energy as function of time are presented. The effects of storage medium, different porosity values and mass flow rate on stored thermal energy and storage time are shown. - Highlights: • HTTES in a honeycomb solid matrix is numerically investigated. • The numerical analysis is carried out assuming the honeycomb as a porous medium. • The Brinkman–Forchheimer–extended Darcy model is used in the governing equations. • Results are carried out for different mass flow rates and porosity values. • The main effect is due to the porosity which set the thermal energy storage value

  1. High-temperature molten salt thermal energy storage systems for solar applications

    Science.gov (United States)

    Petri, R. J.; Claar, T. D.; Ong, E.

    1983-01-01

    Experimental results of compatibility screening studies of 100 salt/containment/thermal conductivity enhancement (TCE) combinations for the high temperature solar thermal application range of 704 deg to 871 C (1300 to 1600 F) are presented. Nine candidate containment/HX alloy materials and two TCE materials were tested with six candidate solar thermal alkali and alkaline earth carbonate storage salts (both reagent and technical grade of each). Compatibility tests were conducted with salt encapsulated in approx. 6.0 inch x 1 inch welded containers of test material from 300 to 3000 hours. Compatibility evaluations were end application oriented, considering the potential 30 year lifetime requirement of solar thermal power plant components. Analyses were based on depth and nature of salt side corrosion of materials, containment alloy thermal aging effects, weld integrity in salt environment, air side containment oxidation, and chemical and physical analyses of the salt. A need for more reliable, and in some cases first time determined thermophysical and transport property data was also identified for molten carbonates in the 704 to 871 C temperature range. In particular, accurate melting point (mp) measurements were performed for Li2CO3 and Na2CO3 while melting point, heat of fusion, and specific heat determinations were conducted on 81.3 weight percent Na2CO3-18.7 weight percent K2CO3 and 52.2 weight percent BaCO3-47.8 weight percent Na2CO3 to support future TES system design and ultimate scale up of solar thermal energy storage (TES) subsystems.

  2. Impacts of convection on high-temperature aquifer thermal energy storage

    Science.gov (United States)

    Beyer, Christof; Hintze, Meike; Bauer, Sebastian

    2016-04-01

    Seasonal subsurface heat storage is increasingly used in order to overcome the temporal disparities between heat production from renewable sources like solar thermal installations or from industrial surplus heat and the heat demand for building climatisation or hot water supply. In this context, high-temperature aquifer thermal energy storage (ATES) is a technology to efficiently store and retrieve large amounts of heat using groundwater wells in an aquifer to inject or withdraw hot or cold water. Depending on the local hydrogeology and temperature amplitudes during high-temperature ATES, density differences between the injected hot water and the ambient groundwater may induce significant convective flow components in the groundwater flow field. As a consequence, stored heat may accumulate at the top of the storage aquifer which reduces the heat recovery efficiency of the ATES system. Also, an accumulation of heat at the aquifer top will induce increased emissions of heat to overlying formations with potential impacts on groundwater quality outside of the storage. This work investigates the impacts of convective heat transport on the storage efficiency of a hypothetical high-temperature ATES system for seasonal heat storage as well as heat emissions to neighboring formations by numerical scenario simulations. The coupled groundwater flow and heat transport code OpenGeoSys is used to simulate a medium scale ATES system operating in a sandy aquifer of 20 m thickness with an average groundwater temperature of 10°C and confining aquicludes at top and bottom. Seasonal heat storage by a well doublet (i.e. one fully screened "hot" and "cold" well, respectively) is simulated over a period of 10 years with biannual injection / withdrawal cycles at pumping rates of 15 m³/h and for different scenarios of the temperature of the injected water (20, 35, 60 and 90 °C). Simulation results show, that for the simulated system significant convective heat transport sets in when

  3. Parametric Investigation of Optimum Thermal Insulation Thickness for External Walls

    Directory of Open Access Journals (Sweden)

    Omer Kaynakli

    2011-06-01

    Full Text Available Numerous studies have estimated the optimum thickness of thermal insulation materials used in building walls for different climate conditions. The economic parameters (inflation rate, discount rate, lifetime and energy costs, the heating/cooling loads of the building, the wall structure and the properties of the insulation material all affect the optimum insulation thickness. This study focused on the investigation of these parameters that affect the optimum thermal insulation thickness for building walls. To determine the optimum thickness and payback period, an economic model based on life-cycle cost analysis was used. As a result, the optimum thermal insulation thickness increased with increasing the heating and cooling energy requirements, the lifetime of the building, the inflation rate, energy costs and thermal conductivity of insulation. However, the thickness decreased with increasing the discount rate, the insulation material cost, the total wall resistance, the coefficient of performance (COP of the cooling system and the solar radiation incident on a wall. In addition, the effects of these parameters on the total life-cycle cost, payback periods and energy savings were also investigated.

  4. Microencapsulation of metal-based phase change material for high-temperature thermal energy storage.

    Science.gov (United States)

    Nomura, Takahiro; Zhu, Chunyu; Sheng, Nan; Saito, Genki; Akiyama, Tomohiro

    2015-03-13

    Latent heat storage using alloys as phase change materials (PCMs) is an attractive option for high-temperature thermal energy storage. Encapsulation of these PCMs is essential for their successful use. However, so far, technology for producing microencapsulated PCMs (MEPCMs) that can be used above 500°C has not been established. Therefore, in this study, we developed Al-Si alloy microsphere MEPCMs covered by α-Al2O3 shells. The MEPCM was prepared in two steps: (1) the formation of an AlOOH shell on the PCM particles using a boehmite treatment, and (2) heat-oxidation treatment in an O2 atmosphere to form a stable α-Al2O3 shell. The MEPCM presented a melting point of 573°C and latent heat of 247 J g(-1). The cycling performance showed good durability. These results indicated the possibility of using MEPCM at high temperatures. The MEPCM developed in this study has great promise in future energy and chemical processes, such as exergy recuperation and process intensification.

  5. Phase competition and anomalous thermal evolution in high-temperature superconductors

    Science.gov (United States)

    Yu, Zuo-Dong; Zhou, Yuan; Yin, Wei-Guo; Lin, Hai-Qing; Gong, Chang-De

    2017-07-01

    The interplay of competing orders is relevant to high-temperature superconductivity known to emerge upon suppression of a parent antiferromagnetic order typically via charge doping. How such interplay evolves at low temperature—in particular at what doping level the zero-temperature quantum critical point (QCP) is located—is still elusive because it is masked by the superconducting state. The QCP had long been believed to follow a smooth extrapolation of the characteristic temperature T* for the strange normal state well above the superconducting transition temperature. However, recently the T* within the superconducting dome was reported to unexpectedly exhibit back-bending likely in the cuprate Bi2Sr2CaCu2O8 +δ . Here we show that the original and revised phase diagrams can be understood in terms of weak and moderate competitions, respectively, between superconductivity and a pseudogap state such as d -density or spin-density wave, based on both Ginzburg-Landau theory and the realistic t -t'-t''-J -V model for the cuprates. We further found that the calculated temperature and doping-level dependence of the quasiparticle spectral gap and Raman response qualitatively agrees with the experiments. In particular, the T* back-bending can provide a simple explanation of the observed anomalous two-step thermal evolution dominated by the superconducting gap and the pseudogap, respectively. Our results imply that the revised phase diagram is likely to take place in high-temperature superconductors.

  6. Effects of thermal - mechanical treatment in the creep - and tensile properties of niobium at high temperature

    International Nuclear Information System (INIS)

    Botta Filho, W.J.; Pinatti, Dyonisio G.

    1981-01-01

    Mechanical behavior of Nb at high temperature was studied based upon the samples morfology. The samples were obtainned after thermal mechanical treatment of 50mm diameter and 250mm length ingot produced by electron beam vacuum. A lot of the samples was tensile tested as a function of temperature showing small interstitials solute effect and a matrix hardened probably by substitutionals. Other lot was creep tested at homologous temperature of 0,34 and stress between 80 and 120 MPa. The results of these tests were analysed as a function of the sample morfology and showed a dependence of the percentage of recrystalization and of the grain size on the minimum creep rate. The fracture analysis showed significant effect of the oxygen content although it didn't contribute to the creep results. (Author) [pt

  7. Thermal coupling of a high temperature PEM fuel cell with a complex hydride tank

    DEFF Research Database (Denmark)

    Pfeifer, P.; Wall, C.; Jensen, Jens Oluf

    2009-01-01

    the possibilities of a thermal coupling of a high temperature PEM fuel cell operating at 160-200 degrees C. The starting temperatures and temperature hold-times before starting fuel cell operation, the heat transfer characteristics of the hydride storage tanks, system temperature, fuel cell electrical power......Sodium alanate doped with cerium catalyst has been proven to have fast kinetics for hydrogen ab- and de-sorption as well as a high gravimetric storage density around 5 wt%. The kinetics of hydrogen sorption can be improved by preparing the alanate as nanocrystalline material. However, the second...... decomposition step, i.e. the decomposition of the hexahydride to sodium hydride and aluminium which refers to 1.8 wt% hydrogen is supposed to happen above 110 degrees C. The discharge of the material is thus limited by the level of heat supplied to the hydride storage tank. Therefore, we evaluated...

  8. 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.

  9. Cast thermally stable high temperature nickel-base alloys and casting made therefrom

    International Nuclear Information System (INIS)

    Acuncius, D.A.; Herchenroeder, R.B.; Kirchner, R.W.; Silence, W.L.

    1977-01-01

    A cast thermally stable high temperature nickel-base alloy characterized by superior oxidation resistance, sustainable hot strength and retention of ductility on aging is provided by maintaining the alloy chemistry within the composition molybdenum 13.7% to 15.5%; chromium 14.7% to 16.5%; carbon up to 0.1%, lanthanum in an effective amount to provide oxidation resistance up to 0.08%; boron up to 0.015%; manganese 0.3% to 1.0%; silicon 0.2% to 0.8%; cobalt up to 2.0%; iron up to 3.0%; tungsten up to 1.0%; copper up to 0.4%; phosphorous up to 0.02%; sulfur up to 0.015%; aluminum 0.1% to 0.5% and the balance nickel while maintaining the Nv number less than 2.31

  10. High-temperature thermal-chemical analysis of nuclear fuel channels

    Energy Technology Data Exchange (ETDEWEB)

    Nekhamkin, Y; Rosenband, V; Hasan, D; Elias, E; Wacholder, E; Gany, A [Technion-Israel Inst. of Tech., Haifa (Israel)

    1996-12-01

    In a severe accident situation, e.g., a postulated loss of coolant accident with a coincident loss of emergency core cooling (LOCA/LOECC), the core may become partially uncovered and steam may become the only coolant available. The thermodynamic conditions in the core, in this case, depend on ability of the steam to effectively remove the fuel decay heat and the heat generated by the exothermic steam/Zircaloy reaction., Therefore, it is important to understand the high-temperature behavior of an oxidizing fuel channel. The main objective of this work is to develop a methodology for calculating the clad temperature and rate of oxidation of a partially covered fuel pin. A criterion is derived to define the importance of the chemical reaction in the overall heat balance. The main parameters affecting the fuel thermal behavior are outlined (authors).

  11. Sensitivity analysis of recovery efficiency in high-temperature aquifer thermal energy storage with single well

    International Nuclear Information System (INIS)

    Jeon, Jun-Seo; Lee, Seung-Rae; Pasquinelli, Lisa; Fabricius, Ida Lykke

    2015-01-01

    High-temperature aquifer thermal energy storage system usually shows higher performance than other borehole thermal energy storage systems. Although there is a limitation in the widespread use of the HT-ATES system because of several technical problems such as clogging, corrosion, etc., it is getting more attention as these issues are gradually alleviated. In this study, a sensitivity analysis of recovery efficiency in two cases of HT-ATES system with a single well is conducted to select key parameters. For a fractional factorial design used to choose input parameters with uniformity, the optimal Latin hypercube sampling with an enhanced stochastic evolutionary algorithm is considered. Then, the recovery efficiency is obtained using a computer model developed by COMSOL Multiphysics. With input and output variables, the surrogate modeling technique, namely the Gaussian-Kriging method with Smoothly Clopped Absolute Deviation Penalty, is utilized. Finally, the sensitivity analysis is performed based on the variation decomposition. According to the result of sensitivity analysis, the most important input variables are selected and confirmed to consider the interaction effects for each case and it is confirmed that key parameters vary with the experiment domain of hydraulic and thermal properties as well as the number of input variables. - Highlights: • Main and interaction effects on recovery efficiency in HT-ATES was investigated. • Reliability depended on fractional factorial design and interaction effects. • Hydraulic permeability of aquifer had an important impact on recovery efficiency. • Site-specific sensitivity analysis of HT-ATES was recommended.

  12. Real time thermal hydraulic model for high temperature gas-cooled reactor core

    International Nuclear Information System (INIS)

    Sui Zhe; Sun Jun; Ma Yuanle; Zhang Ruipeng

    2013-01-01

    A real-time thermal hydraulic model of the reactor core was described and integrated into the simulation system for the high temperature gas-cooled pebble bed reactor nuclear power plant, which was developed in the vPower platform, a new simulation environment for nuclear and fossil power plants. In the thermal hydraulic model, the helium flow paths were established by the flow network tools in order to obtain the flow rates and pressure distributions. Meanwhile, the heat structures, representing all the solid heat transfer elements in the pebble bed, graphite reflectors and carbon bricks, were connected by the heat transfer network in order to solve the temperature distributions in the reactor core. The flow network and heat transfer network were coupled and calculated in real time. Two steady states (100% and 50% full power) and two transients (inlet temperature step and flow step) were tested that the quantitative comparisons of the steady results with design data and qualitative analysis of the transients showed the good applicability of the present thermal hydraulic model. (authors)

  13. Thermal and irradiation effects on high-temperature mechanical properties of materials for SCWR fuel cladding

    International Nuclear Information System (INIS)

    Kano, F.; Tsuchiya, Y.; Oka, K.

    2009-01-01

    The thermal and irradiation effects on high-temperature mechanical properties are examined for candidate alloys for fuel cladding of supercritical water-cooled reactors (SCRWs). JMTR (Japan Materials Testing Reactor) and Experimental Fast Reactor JOYO were utilized for neutron irradiation tests, considering their fluence and temperature. Irradiation was performed with JMTR at 600degC up to 4x10 24 n/m 2 and with JOYO at 600degC and 700degC up to 6x10 25 n/m 2 . Tensile test, creep test and hardness measurement were carried out for high-temperature mechanical properties. Based on the uniaxial creep test, the extrapolation curves were drawn with time-temperature relationships utilizing the Larson and Miller Parameter. Several candidate alloys are expected to satisfy the design requirement from the estimation of the creep rupture stress for 50000 hours. Comparing the creep strengths under irradiated and unirradiated conditions, it was inferred that creep deformation was dominated by the thermal effect rather than the irradiation at SCWR core condition. The microstructure was examined using transmission electron microscope (TEM) analysis, focusing on void swelling and helium (He) bubble formation. Void formation was observed in the materials irradiated with JOYO at 600degC but not at 700degC. However, its effect on the deformation of components was estimated to be tolerable since their size and density were negligibly small. The manufacturability of the thin-wall, small-diameter tube was confirmed for the potential candidate alloys through the trial tests in the factory where the fuel cladding tube is manufactured. (author)

  14. Microstructural characterization of thermal barrier coating on Inconel 617 after high temperature oxidation

    Directory of Open Access Journals (Sweden)

    Mohammadreza Daroonparvar

    2013-06-01

    Full Text Available A turbine blade was protected against high temperature corrosion and oxidation by thermal barrier coatings (TBCsusing atmospheric plasma spraying technique (APS on a Ni-based superalloy (Inconel 617. The coatings (NiCr6AlY/ YSZ and NiCr10AlY/YSZ consist of laminar structure with substantial interconnected porosity transferred oxygen from Yittria stabilized Zirconia (YSZ layer toward the bond coat (NiCrAlY. Hence, a thermally grown oxide layer (TGO was formed on the metallic bond coat and internal oxidation of the bond coat occurred during oxidation. The TBC systems were oxidized in a normal electrically heated furnace at 1150 °C for 18, 22, 26, 32 and 40h.Microstructural characterization of coatings demonstrated that the growth of the TGO layer on the nickel alloy with 6wt. % Al is more rapid than TGO with 10wt. % Al. In addition, many micro-cracks were observed at the interface of NiCr6AlY/YSZ. X-ray diffraction analysis (XRD showed the existence of detrimental oxides such as NiCr2O4, NiCrO3 and NiCrO4 in the bond coat containing 6wt. % Al, accompanied by rapid volume expansion causing the destruction of TBC. In contrast, in the bond coat with 10wt. % Al, NiO, Al2O3and Cr2O3 oxides were formed while very low volume expansion occurred. The oxygen could not penetrate into the TGO layer of bond coat with 10 wt. % Al during high temperature oxidation and the detrimental oxides were not extensively formed within the bond coat as more oxygen was needed. The YSZ with higher Al content showed higher oxidation resistance.

  15. Thermal Transport in High-Strength Polymethacrylimide (PMI) Foam Insulations

    Science.gov (United States)

    Qiu, L.; Zheng, X. H.; Zhu, J.; Tang, D. W.; Yang, S. Y.; Hu, A. J.; Wang, L. L.; Li, S. S.

    2015-11-01

    Thermal transport in high-strength polymethacrylimide (PMI) foam insulations is described, with special emphasis on the density and temperature effects on the thermal transport performance. Measurements of the effective thermal conductivity are performed by a freestanding sensor-based 3ω method. A linear relationship between the density and the effective thermal conductivity is observed. Based on the analysis of the foam insulation morphological structures and the corresponding geometrical cell model, the quantitative contribution of the solid conductivity and the gas conductivity as well as the radiative conductivity to the total effective thermal conductivity as a function of the density and temperature is calculated. The agreement between the curves of the results from the developed model and experimental data indicate the model can be used for PMI foam insulating performance optimization.

  16. Improved Thermal-Insulation Systems for Low Temperatures

    Science.gov (United States)

    Fesmire, James E.; Augustynowicz, Stanislaw D.

    2003-01-01

    Improved thermal-insulation materials and structures and the techniques for manufacturing them are undergoing development for use in low-temperature applications. Examples of low-temperature equipment for which these thermal insulation systems could provide improved energy efficiency include storage tanks for cryogens, superconducting electric-power-transmission equipment, containers for transport of food and other perishable commodities, and cold boxes for low-temperature industrial processes. These systems could also be used to insulate piping used to transfer cryogens and other fluids, such as liquefied natural gas, refrigerants, chilled water, crude oil, or low-pressure steam. The present thermal-insulation systems are layer composites based partly on the older class of thermal-insulation systems denoted generally as multilayer insulation (MLI). A typical MLI structure includes an evacuated jacket, within which many layers of radiation shields are stacked or wrapped close together. Low-thermal-conductivity spacers are typically placed between the reflection layers to keep them from touching. MLI can work very well when a high vacuum level (less than 10(exp-4) torr) is maintained and utmost care is taken during installation, but its thermal performance deteriorates sharply as the pressure in the evacuated space rises into the soft vacuum range [pressures greater than 0.1 torr (greater than 13 Pa)]. In addition, the thermal performance of MLI is extremely sensitive to mechanical compression and edge effects and can easily decrease from one to two orders of magnitude from its ideal value even when the MLI is kept under high vacuum condition. The present thermal-insulation systems are designed to perform well under soft vacuum level, in particular the range of 1 to 10 torr. They are also designed with larger interlayer spacings to reduce vulnerability to compression (and consequent heat leak) caused by installation and use. The superiority of these systems is the

  17. Superconductivity degradation in Gd-containing high temperature superconductors (HTSC) under thermal neutron irradiation

    International Nuclear Information System (INIS)

    Petrov, A.; Kudrenitskis, I.; Makletsov, A.; Arhipov, A.; Karklin, N.

    1999-01-01

    The physical properties of ordered crystals are extremely sensitive to the degree of order in the distribution of the various kinds of atoms over the corresponding sites in the crystal lattice. An increasingly popular means of creating disordered states is to use nuclear radiation. The type of radiation defects which appear and the nature and degree of the structural changes in ordered crystals depend on the kind of radiation and the fluence level, the irradiation temperature, the type of crystal structure, the composition and initial disorder of the material, the character of the interatomic forces, etc. There are many such scientific publications where the effects of fast neutron irradiation on high temperature superconductors (HTSC) have been studied in both polycrystalline and single crystalline superconductors. It is known also that the role of thermal neutrons in structural defects forming is negligible in comparison with fast neutrons because of their small (∼0.025 eV) energy. But it is evident enough that in superconductors containing isotopes with large thermal neutron cross sections the important results concerning the role of point defects could be obtained. Such point defects are creating due to soft displacements of isotopes having interacted with thermal neutrons. Such the possibility of creating point defects in solids including HTSC is investigating by several groups (Austria, USA, China, Latvia) and these investigations have found the support in the person of IAEA. In this review the authors consider the changes brought about by thermal-neutron irradiation (E∼0.025 eV) in the structure, superconducting and magnetic properties of gadolinium containing ordered HTSC with the structure 123, whose extreme electric and magnetic properties continue to attract both research and practical interest. All of the studies reviewed have been done on bulk polycrystalline samples RBa 2 Cu 3 O 7-δ (where R - natural mixture of Gd isotopes, 155 Gd, 157 Gd, 160

  18. Evaluation of mechanical and thermal properties of insulation materials for HTS power devices at liquid nitrogen temperature

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Hyung Seop; Diaz, Mark Angelo [Dept. of Mechanical Design Engineering, Andong National University, Andong (Korea, Republic of)

    2017-06-15

    In superconducting power devices including power cables in which high temperature superconducting (HTS) tapes are utilized, a reliable electrical insulation should be achieved for its maximum performance. For an efficient design of HTS superconducting devices, a comparative evaluation of the mechanical and thermal propperties for various insulation materials at cryogenic temperatures is required. Especially, in the process of the property evaluation of the sheet-shaped insulation materials, anisotropy according to the machining direction should be considered because the mechanical and thermal properties are significantly influenced by the sample orientation. In this study, the cryogenic thermal and mechanical properties of various insulation material sheets such as PPLP, Cryoflex, Teflon, and Kapton were determined considering sample orientation. All samples tested at cryogenic temperature showed significantly higher tensile strength as compared with that of room temperature. The ultimate tensile strength at both temperature conditions significantly depended upon the sample orientation. The thermal properties of the insulation materials exhibited a slight difference among samples depending on the orientation: for the PPLP and Cryoflex, the CD orientation showed larger thermal contraction up to 77 K as compared to the MD one. MD samples in PPLP and Cryoflex showed a lower CTE and thermal contraction which made it more promising as an insulation material due to its comparable CTE with HTS CC tapes.

  19. High-flux/high-temperature solar thermal conversion: technology development and advanced applications

    Directory of Open Access Journals (Sweden)

    Romero Manuel

    2016-01-01

    Full Text Available Solar Thermal Power Plants have generated in the last 10 years a dynamic market for renewable energy industry and a pro-active networking within R&D community worldwide. By end 2015, there are about 5 GW installed in the world, most of them still concentrated in only two countries, Spain and the US, though a rapid process of globalization is taking place in the last few years and now ambitious market deployment is starting in countries like South Africa, Chile, Saudi Arabia, India, United Arab Emirates or Morocco. Prices for electricity produced by today's plants fill the range from 12 to 16 c€/kWh and they are capital intensive with investments above 4000 €/kW, depending on the number of hours of thermal storage. The urgent need to speed up the learning curve, by moving forward to LCOE below 10 c€/kWh and the promotion of sun-to-fuel applications, is driving the R&D programmes. Both, industry and R&D community are accelerating the transformation by approaching high-flux/high-temperature technologies and promoting the integration with high-efficiency conversion systems.

  20. Design and Test of a Thermal Triggered Persistent Current System using High Temperature Superconducting Tapes

    Energy Technology Data Exchange (ETDEWEB)

    Park, Dong Keun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Kang, Hyoungku [Electro-Mechanical Research Institute, Hyundai Heavy Industries, Yongin (Korea, Republic of); Ahn, Min Cheol [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yang, Seong Eun [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Yoon, Yong Soo [Department of Electrical Engineering, Ansan College of Technology, 671 Choji-Dong, Danwon-Gu, Ansan, 425-792 (Korea, Republic of); Lee, Sang Jin [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of); Ko, Tae Kuk [Department of Electrical and Electronic Engineering, Yonsei University, Shinchon-Dong 134, Seodaemun-Gu, Seoul 120-749 (Korea, Republic of)

    2006-06-01

    A superconducting magnet which is operated in persistent current mode in SMES, NMR, MRI and MAGLEV has many advantages such as high uniformity of magnetic field and reduced thermal loss. A high temperature superconducting (HTS) persistent current switch (PCS) system was designed and tested in this research. The HTS PCS was optimally designed using two different HTS tapes, second generation coated conductor (CC) HTS tape and Bi-2223 HTS tape by the finite element method (FEM) in thermal quench characteristic view. The CC tape is more prospective applicable wire in these days for its high n value and critical current independency from external magnetic field than Bi-2223 tape. Also a prototype PCS system using Bi-2223 tape was manufactured and tested. The PCS system consists of a PCS part, a heater which induces the PCS to quench, and a superconducting magnet. The test was performed in various conditions of transport current. An initial current decay appeared when the superconducting magnet was energized in a PCS system was analyzed. This paper would be foundation of HTS PCS researches.

  1. A new technique for precise measurement of thermal conductivity of metals at normal and high temperatures

    International Nuclear Information System (INIS)

    Binkele, L.

    1990-09-01

    Theoretical and experimental investigations on a new measuring technique are described; a technique similar to the well known Kohlrausch measuring technique, which is characterized by direct electrical sample heating. Subject of the investigations is a cylindrical metallic sample, 5 mm thick and 200 mm in length, which is positioned vertically between water-cooled clamps in a vacuum container. The sample can be heated using two simultaneously operating current sources, a 50 Hz-source for axial flow (main heating) as well as a 200 kHz-induction source for generating eddy currents in two short regions above and below the sample centre (additional heating). By using two heating sources different symmetrical temperature profiles in a central eddy-current-free area of about ± 10mm can be produced for any given central sample temperature. The last chapter contains thermal conductivity and electrical resistivity measuring curves for Pt, W, Fe, Ni, Ag, Al, Mg, Ir, Ru, Re, Ho and Y in the temperature range 273 to 1500 K representative of all the metals and alloys investigated. In cases where comparisons with published precise conductivity data, established by other measuring techniques in restricted temperature ranges, were posible, the new measuring method is greatly supported (in the case of Pt, W, Ni, Ag, Al). For the Metals Ir, Ru, Re, Ho and Y high temperature thermal conductivity data are given for the first time. (orig./MM) [de

  2. Characterization of thermally sprayed coatings for high-temperature wear-protection applications

    International Nuclear Information System (INIS)

    Li, C.C.

    1980-03-01

    Under normal high-temperature gas-cooled reactor (HTGR) operating conditions, faying surfaces of metallic components under high contact pressure are prone to friction, wear, and self-welding damage. Component design calls for coatings for the protection of the mating surfaces. Anticipated operating temperatures up to 850 to 950 0 C (1562 to 1742 0 F) and a 40-y design life require coatings with excellent thermal stability and adequate wear and spallation resistance, and they must be compatible with the HTGR coolant helium environment. Plasma and detonation-gun (D-gun) deposited chromium carbide-base and stabilized zirconia coatings are under consideration for wear protection of reactor components such as the thermal barrier, heat exchangers, control rods, and turbomachinery. Programs are under way to address the structural integrity, helium compatibility, and tribological behavior of relevant sprayed coatings. In this paper, the need for protection of critical metallic components and the criteria for selection of coatings are discussed. The technical background to coating development and the experience with the steam cycle HTGR (HTGR-SC) are commented upon. Coating characterization techniques employed at General Atomic Company (GA) are presented, and the progress of the experimental programs is briefly reviewed. In characterizing the coatings for HTGR applications, it is concluded that a systems approach to establish correlation between coating process parameters and coating microstructural and tribological properties for design consideration is required

  3. A new thermal conductivity probe for high temperature tests for the characterization of molten salts

    Science.gov (United States)

    Bovesecchi, G.; Coppa, P.; Pistacchio, S.

    2018-05-01

    A new thermal conductivity probe for high temperature (HT-TCP) has been built and tested. Its design and construction procedure are adapted from the ambient temperature thermal conductivity probe (AT-TCP) due to good performance of the latter device. The construction procedure and the preliminary tests are accurately described. The probe contains a Pt wire as a heater and a type K thermocouple (TC) as a temperature sensor, and its size is so small (0.6 mm in diameter and 60 mm in length) as to guarantee a length to diameter ratio of about 100. Calibration tests with glycerol for temperatures between 0 °C and 60 °C have shown good agreement with literature data, within 3%. Preliminary tests were also carried on a ternary molten salt for Concentrated Solar Power (CSP) (18% in mass of NaNO3, 52% KNO3, and 30% LiNO3) at 120 °C and 150 °C. Obtained results are within λ range of the Hitec® salt (53% KNO3, 7% NaNO3, 40% NaNO2). Unfortunately, at the higher temperature tested (200 °C), the viscosity of the salt highly decreases, and free convection starts, making the measurements unreliable.

  4. Development and Performance Evaluation of High Temperature Concrete for Thermal Energy Storage for Solar Power Generation

    Energy Technology Data Exchange (ETDEWEB)

    Selvam, R. Panneer; Hale, Micah; Strasser, Matt

    2013-03-31

    Thermal energy can be stored by the mechanism of sensible or latent heat or heat from chemical reactions. Sensible heat is the means of storing energy by increasing the temperature of the solid or liquid. Since the concrete as media cost per kWhthermal is $1, this seems to be a very economical material to be used as a TES. This research is focused on extending the concrete TES system for higher temperatures (500 °C to 600 °C) and increasing the heat transfer performance using novel construction techniques. To store heat at high temperature special concretes are developed and tested for its performance. The storage capacity costs of the developed concrete is in the range of $0.91-$3.02/kWhthermal. Two different storage methods are investigated. In the first one heat is transported using molten slat through a stainless steel tube and heat is transported into concrete block through diffusion. The cost of the system is higher than the targeted DOE goal of $15/kWhthermal. The increase in cost of the system is due to stainless steel tube to transfer the heat from molten salt to the concrete blocks.The other method is a one-tank thermocline system in which both the hot and cold fluid occupy the same tank resulting in reduced storage tank volume. In this model, heated molten salt enters the top of the tank which contains a packed bed of quartzite rock and silica sand as the thermal energy storage (TES) medium. The single-tank storage system uses about half the salt that is required by the two-tank system for a required storage capacity. This amounts to a significant reduction in the cost of the storage system. The single tank alternative has also been proven to be cheaper than the option which uses large concrete modules with embedded heat exchangers. Using computer models optimum dimensions are determined to have an round trip efficiency of 84%. Additionally, the cost of the structured concrete thermocline configuration provides the TES

  5. The Development of an INL Capability for High Temperature Flow, Heat Transfer, and Thermal Energy Storage with Applications in Advanced Small Modular Reactors, High Temperature Heat Exchangers, Hybrid Energy Systems, and Dynamic Grid Energy Storage C

    International Nuclear Information System (INIS)

    Sun, Xiaodong; Zhang, Xiaoqin; Kim, Inhun; O'Brien, James; Sabharwall, Piyush

    2014-01-01

    The overall goal of this project is to support Idaho National Laboratory in developing a new advanced high temperature multi fluid multi loop test facility that is aimed at investigating fluid flow and heat transfer, material corrosion, heat exchanger characteristics and instrumentation performance, among others, for nuclear applications. Specifically, preliminary research has been performed at The Ohio State University in the following areas: 1. A review of fluoride molten salts' characteristics in thermal, corrosive, and compatibility performances. A recommendation for a salt selection is provided. Material candidates for both molten salt and helium flow loop have been identified. 2. A conceptual facility design that satisfies the multi loop (two coolant loops [i.e., fluoride molten salts and helium]) multi purpose (two operation modes [i.e., forced and natural circulation]) requirements. Schematic models are presented. The thermal hydraulic performances in a preliminary printed circuit heat exchanger (PCHE) design have been estimated. 3. An introduction of computational methods and models for pipe heat loss analysis and cases studies. Recommendations on insulation material selection have been provided. 4. An analysis of pipe pressure rating and sizing. Preliminary recommendations on pipe size selection have been provided. 5. A review of molten fluoride salt preparation and chemistry control. An introduction to the experience from the Molten Salt Reactor Experiment at Oak Ridge National Laboratory has been provided. 6. A review of some instruments and components to be used in the facility. Flowmeters and Grayloc connectors have been included. This report primarily presents the conclusions drawn from the extensive review of literatures in material selections and the facility design progress at the current stage. It provides some useful guidelines in insulation material and pipe size selection, as well as an introductory review of facility process and

  6. The Development of an INL Capability for High Temperature Flow, Heat Transfer, and Thermal Energy Storage with Applications in Advanced Small Modular Reactors, High Temperature Heat Exchangers, Hybrid Energy Systems, and Dynamic Grid Energy Storage C

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiaodong [The Ohio State Univ., Columbus, OH (United States); Zhang, Xiaoqin [The Ohio State Univ., Columbus, OH (United States); Kim, Inhun [The Ohio State Univ., Columbus, OH (United States); O' Brien, James [Idaho National Lab. (INL), Idaho Falls, ID (United States); Sabharwall, Piyush [Idaho National Lab. (INL), Idaho Falls, ID (United States)

    2014-10-01

    The overall goal of this project is to support Idaho National Laboratory in developing a new advanced high temperature multi fluid multi loop test facility that is aimed at investigating fluid flow and heat transfer, material corrosion, heat exchanger characteristics and instrumentation performance, among others, for nuclear applications. Specifically, preliminary research has been performed at The Ohio State University in the following areas: 1. A review of fluoride molten salts’ characteristics in thermal, corrosive, and compatibility performances. A recommendation for a salt selection is provided. Material candidates for both molten salt and helium flow loop have been identified. 2. A conceptual facility design that satisfies the multi loop (two coolant loops [i.e., fluoride molten salts and helium]) multi purpose (two operation modes [i.e., forced and natural circulation]) requirements. Schematic models are presented. The thermal hydraulic performances in a preliminary printed circuit heat exchanger (PCHE) design have been estimated. 3. An introduction of computational methods and models for pipe heat loss analysis and cases studies. Recommendations on insulation material selection have been provided. 4. An analysis of pipe pressure rating and sizing. Preliminary recommendations on pipe size selection have been provided. 5. A review of molten fluoride salt preparation and chemistry control. An introduction to the experience from the Molten Salt Reactor Experiment at Oak Ridge National Laboratory has been provided. 6. A review of some instruments and components to be used in the facility. Flowmeters and Grayloc connectors have been included. This report primarily presents the conclusions drawn from the extensive review of literatures in material selections and the facility design progress at the current stage. It provides some useful guidelines in insulation material and pipe size selection, as well as an introductory review of facility process and components.

  7. Interior thermal insulation systems for historical building envelopes

    Science.gov (United States)

    Jerman, Miloš; Solař, Miloš; Černý, Robert

    2017-11-01

    The design specifics of interior thermal insulation systems applied for historical building envelopes are described. The vapor-tight systems and systems based on capillary thermal insulation materials are taken into account as two basic options differing in building-physical considerations. The possibilities of hygrothermal analysis of renovated historical envelopes including laboratory methods, computer simulation techniques, and in-situ tests are discussed. It is concluded that the application of computational models for hygrothermal assessment of interior thermal insulation systems should always be performed with a particular care. On one hand, they present a very effective tool for both service life assessment and possible planning of subsequent reconstructions. On the other, the hygrothermal analysis of any historical building can involve quite a few potential uncertainties which may affect negatively the accuracy of obtained results.

  8. Response of Compacted Bentonites to Thermal and Thermo-Hydraulic Loadings at High Temperatures

    Directory of Open Access Journals (Sweden)

    Snehasis Tripathy

    2017-07-01

    Full Text Available The final disposal of high-level nuclear waste in many countries is preferred to be in deep geological repositories. Compacted bentonites are proposed for use as the buffer surrounding the waste canisters which may be subjected to both thermal and hydraulic loadings. A significant increase in the temperature is anticipated within the buffer, particularly during the early phase of the repository lifetime. In this study, several non-isothermal and non-isothermal hydraulic tests were carried on compacted MX80 bentonite. Compacted bentonite specimens (water content = 15.2%, dry density = 1.65 Mg/m3 were subjected to a temperature of either 85 or 150 °C at one end, whereas the temperature at the opposite end was maintained at 25 °C. During the non-isothermal hydraulic tests, water was supplied from the opposite end of the heat source. The temperature and relative humidity were monitored along predetermined depths of the specimens. The profiles of water content, dry density, and degree of saturation were established after termination of the tests. The test results showed that thermal gradients caused redistribution of the water content, whereas thermo-hydraulic gradients caused both redistribution and an increase in the water content within compacted bentonites, both leading to development of axial stress of various magnitudes. The applied water injection pressures (5 and 600 kPa and temperature gradients appeared to have very minimal impact on the magnitude of axial stress developed. The thickness of thermal insulation layer surrounding the testing devices was found to influence the temperature and relative humidity profiles thereby impacting the redistribution of water content within compacted bentonites. Under the influence of both the applied thermal and thermo-hydraulic gradients, the dry density of the bentonite specimens increased near the heat source, whereas it decreased at the opposite end. The test results emphasized the influence of

  9. Testing and analyses of a high temperature thermal barrier for gas-cooled reactors

    International Nuclear Information System (INIS)

    Black, W.E.; Betts, W.S.; Felten, P.

    1979-01-01

    A full size, multi-panel section of a thermal barrier system was fabricated from a nickel-base superalloy and a combination of fibrous blanket insulation materials for specific application in a steam cycle gas-cooled nuclear reactor. The 2.4 m square array was representative of the sidewall of the lower core outlet plenum and included coverplates, attachments, seals, and a simulated water-cooled liner. Testing was conducted in a reactor grade, helium-filled chamber at 816 0 C for 100 hours, which established a normal (baseline) condition; 982 0 C for 10 hours, which satisfied an emergency condition; 1093 0 C for 1 hour, which simulated a faulted condition; and 1260 0 C, which was a non-design condition test to demonstrate the temperature overshoot capability of the system. Post-test examination indicated: (1) an acceptable performance by the anti-friction chromium carbide (Cr 3 C 2 ) coating; (2) no significant galling between non-coated surfaces; (3) no distortion of attachment fixtures; (4) predictable coverplate deflection during the design conditions testing (normal, emergency, and faulted); and (5) considerable plastic deformation resulting from the near-incipient melting temperature. (orig.)

  10. Effects of a Mixed Zone on TGO Displacement Instabilities of Thermal Barrier Coatings at High Temperature in Gas-Cooled Fast Reactors

    Directory of Open Access Journals (Sweden)

    Jian Wang

    2016-01-01

    Full Text Available Thermally grown oxide (TGO, commonly pure α-Al2O3, formed on protective coatings acts as an insulation barrier shielding cooled reactors from high temperatures in nuclear energy systems. Mixed zone (MZ oxide often grows at the interface between the alumina layer and top coat in thermal barrier coatings (TBCs at high temperature dwell times accompanied by the formation of alumina. The newly formed MZ destroys interface integrity and significantly affects the displacement instabilities of TGO. In this work, a finite element model based on material property changes was constructed to investigate the effects of MZ on the displacement instabilities of TGO. MZ formation was simulated by gradually changing the metal material properties into MZ upon thermal cycling. Quantitative data show that MZ formation induces an enormous stress in TGO, resulting in a sharp change of displacement compared to the alumina layer. The displacement instability increases with an increase in the MZ growth rate, growth strain, and thickness. Thus, the formation of a MZ accelerates the failure of TBCs, which is in agreement with previous experimental observations. These results provide data for the understanding of TBC failure mechanisms associated with MZ formation and of how to prolong TBC working life.

  11. High-temperature multiphase flowmeters in heavy-oil thermal production

    Energy Technology Data Exchange (ETDEWEB)

    Mehdizadeh, P. [Society of Petroleum Engineers, Richardson, TX (United States)]|[Production Technology Inc. (United States)

    2005-11-01

    A review of field tests assessing the capability and advantages of multi-phase metering technology in high temperature thermal recovery processes such as cyclic steam stimulation (CSS) and steam assisted gravity drainage (SAGD) was presented. A number of different tank gauging procedures were conducted to obtain a reference flow rate. Subsequent performance tests of metered data and tank data verified the accuracy of the meter, and that water cut sampling can be attained under practical field conditions. A 12 well field test was then conducted, and an allocation factor was obtained from conventional test separators and production measurements. An improvement in the allocation factor was noted. However, a full evaluation of the multiphase meter data obtained in the field was limited by the quality of the reference field data. A 30 day well testing campaign showed a comparison of well rate data from the multi-phase meter with data from an emulsion meter. It was concluded that the multiphase meter provided consistent measurements, matching the level of accuracy attained from rigorous tank measurements. In addition, the multiphase meter eliminated the need for the equipment modifications and extra personnel interventions needed to perform tank testing and manual and automatic water cut sampling. 15 refs., 2 tabs., 6 figs.

  12. High Temperature Test Possibility at the HANARO Out-core Region through a Thermal Analysis

    International Nuclear Information System (INIS)

    Kang, Young-Hwan; Choi, Myung-Hwan; Cho, Man-Soon; Choo, Kee-Nam; Kim, Bong-Goo

    2007-01-01

    The development of an advanced reactor system such as a next generation nuclear plant and other generation IV systems require new fuels, claddings, and structural materials. To characterize the performance of these new materials, it is necessary for us to have a leading-edge technology to satisfy the specific test requirements such as the conditions of high neutron exposures and high operating temperatures. Thus, nuclear data on HANARO's vertical test holes have been gathered and reviewed to evaluate the usability of the test holes located at the out-core zone of HANARO. In 2007, neutron flux levels of the concerned test holes and the gamma heat of the specimens and two different specimen holder materials of Al and Mo at the concerned test hole were obtained to enhance the utilization of the HANARO reactor and to develop new design concepts for high temperature irradiation tests. Based on the data, a series of thermal analyses was implemented to provide a reasonable demonstration and guidance on limitations or application

  13. Thermal and nonthermal electron cyclotron emission by high-temperature tokamak plasmas

    International Nuclear Information System (INIS)

    Airoldi, A.; Ramponi, G.

    1997-01-01

    An analysis of the electron cyclotron emission (ECE) spectra emitted by a high-temperature tokamak plasma in the frequency range of the second and third harmonic of the electron cyclotron frequency is made, both in purely Maxwellian and in non-Maxwellian cases (i.e., in the presence of a current-carrying superthermal tail). The work is motivated mainly by the experimental observations made in the supershot plasmas of the Tokamak Fusion Test Reactor (TFTR), where a systematic disagreement is found between the T e measurements by second-harmonic ECE and Thomson scattering. We show that, by properly taking into account the overlap of superthermals-emitted third harmonic with second-harmonic bulk emission, the radiation temperature observed about the central frequency of the second harmonic may be enhanced up to 30%endash 40% compared to the corresponding thermal value. Moreover we show that, for parameters relevant to the International Thermonuclear Experimental Reactor (ITER) with T e (0)>7 keV, the overlap between the second and the downshifted third harmonic seriously affects the central plasma region, so that the X-mode emission at the second harmonic becomes unsuitable for local T e measurements. copyright 1997 American Institute of Physics

  14. A high temperature ceramic heat exchanger element for a solar thermal receiver

    Science.gov (United States)

    Strumpf, H. J.; Kotchick, D. M.; Coombs, M. G.

    1982-01-01

    The development of a high-temperature ceramic heat exchanger element to be integrated into a solar receiver producing heated air was studied. A number of conceptual designs were developed for heat exchanger elements of differing configuration. These were evaluated with respect to thermal performance, pressure drop, structural integrity, and fabricability. The final design selection identified a finned ceramic shell as the most favorable concept. The shell is surrounded by a larger metallic shell. The flanges of the two shells are sealed to provide a leak-tight pressure vessel. The ceramic shell is to be fabricated by a innovative combination of slip casting the receiver walls and precision casting the heat transfer finned plates. The fins are bonded to the shell during firing. The unit is sized to produce 2150 F air at 2.7 atm pressure, with a pressure drop of about 2 percent of the inlet pressure. This size is compatible with a solar collector providing a receiver input of 85 kw(th). Fabrication of a one-half scale demonstrator ceramic receiver was completed.

  15. High-temperature ceramic heat exchanger element for a solar thermal receiver

    Science.gov (United States)

    Strumpf, H. J.; Kotchick, D. M.; Coombs, M. G.

    1982-01-01

    A study was performed by AiResearch Manufacturing Company, a division of The Garrett Corporation, on the development a high-temperature ceramic heat exchanger element to be integrated into a solar receiver producing heated air. A number of conceptual designs were developed for heat exchanger elements of differing configuration. These were evaluated with respect to thermal performance, pressure drop, structural integrity, and fabricability. The final design selection identified a finned ceramic shell as the most favorable concept. The shell is surrounded by a larger metallic shell. The flanges of the two shells are sealed to provide a leak-tight pressure vessel. The ceramic shell is to be fabricated by an innovative combination of slip casting the receiver walls and precision casting the heat transfer finned plates. The fins are bonded to the shell during firing. The unit is sized to produce 2150 F ar at 2.7 atm pressure, with a pressure drop of about 2 percent of the inlet pressure. This size is compatible with a solar collector providing a receiver input of 85 kw(th). Fabrication of a one-half scale demonstrator ceramic receiver has been completed.

  16. High-Temperature Wide Thermal Hysteresis of an Iron(II Dinuclear Double Helicate

    Directory of Open Access Journals (Sweden)

    Shiori Hora

    2017-07-01

    Full Text Available Two new dinuclear iron(II complexes (1·PF6 and 1·AsF6 of the general formula [FeII2(L2C32](X4·nH2O·mMeCN (X = PF6, n = m = 1.5 for 1·PF6 and X = AsF6, n = 3, m = 1 for 1·AsF6 have been prepared and structurally characterized, where L2C3 is a bis-1,2,3-triazolimine type Schiff-base ligand, 1,1′-[propane-1,3-diylbis(1H-1,2,3-triazole-1,4-diyl]bis{N-[2-(pyridin-2-ylethyl]methanimine}. Single crystal X-ray structure analyses revealed that 1·PF6 and 1·AsF6 are isostructural. The complex-cation [FeII2(L2C32]4+ of both has the same dinuclear double helicate architecture, in which each iron(II center has an N6 octahedral coordination environment. Neighboring helicates are connected by intermolecular π–π interactions to give a chiral one-dimensional (1D structure, and cationic 1D chains with the opposite chirality exist in the crystal lattice to give a heterochiral crystal. Magnetic and differential scanning calorimetry (DSC studies were performed only for 1·AsF6, since the thermal stability in a high-temperature spin crossover (SCO region of 1·PF6 is poorer than that of 1·AsF6. 1·AsF6 shows an unsymmetrical hysteretic SCO between the low-spin–low-spin (LS–LS and high-spin–high-spin (HS–HS states at above room temperature. The critical temperatures of warming (Tc↑ and cooling (Tc↓ modes in the abrupt spin transition area are 485 and 401 K, respectively, indicating the occurrence of 84 K-wide thermal hysteresis in the first thermal cycle.

  17. Thermal performance of various multilayer insulation systems below 80K

    International Nuclear Information System (INIS)

    Boroski, W.N.; Nicol, T.H.; Schoo, C.J.

    1992-04-01

    The SSC collider dipole cryostat consists of a vacuum shell operating at room temperature, two thermal shields operating near 80K and 20K respectively, and the superconducting magnet assembly operating near 4K. The cryostat design incorporates multilayer insulation (MLI) blankets to limit radiant heat transfer into the 80K and 20K thermal shields. Also, an MLI blanket is used to impede heat transfer through residual gas conduction into the 4K superconducting magnet assembly. A measurement facility at Fermilab has been used to experimentally optimize the thermal insulation system for the dipole cryostat. Previous thermal measurements have been used to define the 80K MLI system configuration and verify system performance. With the 80K MLI system defined, the current effort has focused on experimentally defining the optimum insulation scheme for the 20K thermal shield. The SSC design specification requires that radiant heat transfer be limited to 0.093 W/m 2 at an insulating vacuum of 10 -6 torr

  18. Detection of insulation flaws and thermal bridges in insulated truck box panels

    OpenAIRE

    Lei, Lei; Bortolin, Alessandro; Bison, Paolo ©; Maldague, X.

    2017-01-01

    This paper focuses on the detection of defects and thermal bridges in insulated truck box panels, utilising infrared thermography. Unlike the traditional way in which passive thermography is applied, this research uses both heating and cooling methods in active thermography configurations. Lamp heating is used as the hot external stimulation, while a compressed air jet is applied as the cold external stimulation. A thermal camera captures the whole process. In addition, numerical simulations ...

  19. Air-Filled Nanopore Based High-Performance Thermal Insulation Materials

    OpenAIRE

    Gangåssæter, Haakon Fossen; Jelle, Bjørn Petter; Alex Mofid, Sohrab; Gao, Tao

    2017-01-01

    State-of-the-art thermal insulation solutions like vacuum insulation panels (VIP) and aerogels have low thermal conductivity, but their drawbacks may make them unable to be the thermal insulation solutions that will revolutionize the building industry regarding energy-efficient building envelopes. Nevertheless, learning from these materials may be crucial to make new and novel high-performance thermal insulation products. This study presents a review on the state-of-the-art air-filled thermal...

  20. Cardboard Based Packaging Materials as Renewable Thermal Insulation of Buildings: Thermal and Life Cycle Performance

    OpenAIRE

    Čekon, Miroslav; Struhala, Karel; Slávik, Richard

    2017-01-01

    Cardboard based packaging components represent a material with a significant potential of renewable exploitation in buildings. This study presents the results of thermal and environmental analysis of existing packaging materials compared with standard conventional thermal insulations. Experimental measurements were performed to identify the thermal performance of studied cardboard packaging materials. Real-size samples were experimentally tested in laboratory measurements. The thermal resi...

  1. An experimental study on damping characteristics of thermal insulation

    International Nuclear Information System (INIS)

    Chiba, Toshio; Kobayashi, Hiroe; Aida, Shigekazu; Wada, Hidetoshi

    1984-01-01

    The damping ratio is one of the most important parameters in seismic analysis of piping systems in a nuclear power plant. Thermal insulation is considered contributing to the damping characteristics of piping systems. At the 6th SMiRT and 1983 ASME PVP conferences, the damping effect and damping estimating formula were presented as a result of regression analysis using the component test data for 2,4 and 8B diameter piping and the proof model test for 1,2 and 4B piping system. In this study, in order to clarify the damping characteristics of a larger diameter piping than 8B,the component test of 12 and 20B diameter piping with insulation was performed. From the results of these tests and the data survey of the previous papers, it was found that the damping ratio of anactual piping system with thermal insulation is at minimum 1% for all size diameter piping. (author)

  2. An experimental study on damping characteristics of thermal insulation

    International Nuclear Information System (INIS)

    Chiba, T.; Kobayashi, H.

    1985-01-01

    The damping ratio is one of the most important parameters in seismic analysis of nuclear power plant piping systems. Thermal Insulation is considered to contribute to the damping characteristics of piping systems. In the 6th SMiRT conference and 1983 ASME PVP, the damping effect and damping estimating formula was presented as a result of regression analysis from the component tests of 2'' , 4'', and 8'' diameter piping and the proof model test of 1'', 2'' and 4'' piping. In this study, in order to clarify the damping characteristics of larger diameter piping than 8'', the component test of 12'' and 20'' diameter piping with insulation was performed. From the results of these tests and the data survey of the previous papers it was found that the damping ratio of actual piping system with thermal insulation is at least 1% for all size diameter piping

  3. Computational study of a high-temperature thermal nanoimprint lithographic (TNIL) process

    Science.gov (United States)

    Cleveland, Nicolas Joseph

    As an emerging manufacturing technique, nanoimprint lithography (NIL) can fabricate micro and nanoscale features of microfluidic devices at very high accuracy and reliability. The process parameters such as pressure, temperature, and material properties play critical roles in the NIL process. In this work, the process of thermal nanoimprint lithography (TNIL) is studied computationally and the developed model can accurately predict the nano and micro-pattern geometry and quality from TNIL processes based on complex mold-resist interaction. Applications of this modeling technique range from micro- and nano-patterns used in micro-channels for biomedical devices to other applications such as biological/particle sensors or superhydrophobic surfaces. In high-temperature TNIL process, a polymer melt such as polymethyl-methacrylate (PMMA) is heated beyond the melting temperature so that it behaves predominantly as a fluid during the imprint process. The effects of surface tension and shear thinning become significant at or above the melting point, whereas the polymer melt can be modeled as a viscoelastic solid, solved with finite element analysis, when process temperature remains between the glass transition and melting temperatures. Additionally, the mold used in TNIL can deform since it is made of soft-rubbery elastomer such as polydimethylsiloxane (PDMS), and it is of interest to include the effect of subsequent mold deformation. Leakage between channels or significant variation in channel width can occur in micro-fluidic devices if mold deformation exceeds design tolerances. In the current work, fluid-structure interaction (FSI) technology is leveraged to solve for significant mold deformation and its effect on the polymer melt flow field during TNIL process. The simulation result is compared to experimental results. The FSI simulation result is also compared to the equivalent case with a rigid mold in place of flexible material, which shows results of differing mold

  4. Conceptual market potential framework of high temperature aquifer thermal energy storage - A case study in the Netherlands

    NARCIS (Netherlands)

    Wesselink, Maxim; Liu, Wen; Koornneef, Joris; van den Broek, Machteld

    2018-01-01

    High temperature aquifer thermal energy storage (HT-ATES) can contribute to the integration of renewable energy sources in the energy system, the replacement of fossil fuel-based heat supply and the utilization of surplus heat from industrial sources. However, there is limited understanding on the

  5. Parametric fuselage design : Integration of mechanics and acoustic & thermal insulation

    NARCIS (Netherlands)

    Krakers, L.A.

    2009-01-01

    Designing a fuselage is a very complex process, which involves many different aspects like strength and stability, fatigue, damage tolerance, fire resistance, thermal and acoustic insulation but also inspection, maintenance, production and repair aspects. It is difficult to include all design

  6. Electrically and Thermally Insulated Joint for Liquid Nitrogen Transfer

    DEFF Research Database (Denmark)

    Rasmussen, Carsten; Jensen, Kim Høj; Holbøll, Joachim T.

    1999-01-01

    A prototype of a superconducting cable is currently under construction. The cable conductor is cooled by liquid nitrogen in order to obtain superconductivity. The peripheral cooling circuit is kept at ground potential. This requires a joint which insulates both electrically and thermally...

  7. Thermal insulation of buildings is worth the effort

    International Nuclear Information System (INIS)

    Novotny, A.

    1999-01-01

    Thermal insulation of buildings became a vital measure of keeping control of utility bills, elimination of hygienic and visual defects, of water penetration into the structural components and thus prevention, and of thermal stress reduction of the load-carrying structures. Thermal insulation became a substantial part of the residential housing renewal. The current housing status implies that no more time can be wasted in implementing this programme, and its immediate application should be much more extensive than the past attempts. The Reduced Power Consumption Programme proposed in 1990 for the general operation of buildings was addressed in 1991/1995. It was meant to stipulate conditions and demonstrate a reduced power demand for residential heating by 30 %, or subsequent reduction of the power demand to the level of 9.3, 7.3 to 3.1 MWh/standard flat annually (130, 102 and 84 kWh/m 2 year respectively. The assessment of the existing residential housing prove its high power intensity. The real power consumption is in the range of 160-195 kWh/m 2 year. The benefit of the thermal insulation programme is primarily in a reduced need for the state subsidies for the residential heating by at least 1703 slovak crowns per flat. The utility bills savings from insulating two flats are sufficient to heat a third flat. Further benefits can be seen in lower demand on primary power sources and in creating new jobs as well as in positive environmental effects

  8. The Improvement of Thermal Insulating Concrete Panel

    Directory of Open Access Journals (Sweden)

    Mohammed Ali Nasser Ali

    2018-05-01

    Full Text Available The Iraqi houses flattening the roof by a concrete panel, and because of the panels on the top directly exposed to the solar radiation become unbearably hot and cold during the summer and winter. The traditional concrete panel components are cement, sand, and aggregate, which have a poor thermal property. The usage of materials with low thermal conductivity with no negative reflects on its mechanical properties gives good improvements to the thermal properties of the concrete panel. The practical part of this work was built on a multi-stage mixing plan. In the first stage the mixing ratio based on the ratios of the sand to cement. The second stage mixing ratios based on replacing the coarse aggregate quantities with the Alabaster aggregates, and the third stage the mixing ratios based on the replacement of wood ash instead of the sand. While the fourth stage mixing ratios based on decreasing the thermal conductivity and increasing mechanical properties by adding a multilayer of a plastic net. The result shows that using a concrete panel with components (cement, sand, coarse aggregate, wood ash, and Alabaster aggregates with a mass ratio of (1:1:2:1:1 and 3-plastic layers, gives the best improvement of the thermal properties. Where, the thermal conductivity is reduced by 42% and the specific heat increased by 41.2% as compared to the traditional concrete panel mixing ratio, with mechanical properties are agreed with the Iraqi standards.

  9. Wood moisture monitoring during log house thermal insulation mounting

    Directory of Open Access Journals (Sweden)

    Pavla Kotásková

    2011-01-01

    Full Text Available The current designs of thermal insulation for buildings concentrate on the achievement of the required heat transmission coefficient. However, another factor that cannot be neglected is the assessment of the possible water vapour condensation inside the construction. The aim of the study was to find out whether the designed modification of the cladding structure of an existing log house will or will not lead to a risk of possible water vapour condensation in the walls after an additional thermal insulation mounting. The condensation could result in the increase in moisture of the walls and consequently the constructional timber, which would lead to the reduction of the timber construction strength, wood degradation by biotic factors – wood-destroying insects, mildew or wood-destroying fungi. The main task was to compare the theoretically established values of moisture of the constructional timber with the values measured inside the construction using a specific example of a thermal insulated log house. Three versions of thermal insulation were explored to find the solution of a log house reconstruction which would be the optimum for living purposes. Two versions deal with the cladding structure with the insulation from the interior, the third version deals with an external insulation.In a calculation model the results can be affected to a great degree by input values (boundary conditions. This especially concerns the factor of vapour barrier diffusion resistance, which is entered in accordance with the producer’s specifications; however, its real value can be lower as it depends on the perfectness and correctness of the technological procedure. That is why the study also includes thermal technical calculations of all designed insulation versions in the most unfavourable situation, which includes the degradation of the vapour barrier down to 10% efficiency, i.e. the reduction of the diffusion resistance factor to 10% of the original value

  10. Thermal Degradation Study of IM7/DMBZ-15 High Temperature Composite by TGA/FTIR

    National Research Council Canada - National Science Library

    Nadler, Melvin

    2003-01-01

    (U) High temperature graphite composites such as IM7/8552 epoxy, IM7/5250 BMI, and IM7/DMBZ-15 polyimide show blistering and/or "catastrophic" delamination when rapidly heated to temperatures above...

  11. Influence of PCMs in thermal insulation on thermal behaviour of building envelopes

    Science.gov (United States)

    Dydek, K.; Furmański, P.; Łapka, P.

    2016-09-01

    A model of heat transfer through a wall consisting of a layer of concrete and PCM enhanced thermal insulation is considered. The model accounts for heat conduction in both layers, thermal radiation and heat absorption/release due to phase change in the insulation as well as time variation in the ambient temperature and insolation. Local thermal equilibrium between encapsulated PCM and light-weight thermal insulation was assumed. Radiation emission, absorption and scattering were also accounted for in the model. Comparison of different cases of heat flow through the building envelope was carried out. These cases included presence or absence of PCM and thermal radiation in the insulation, effect of emissivity of the PCM microcapsules as well as an effect of solar radiation or its lack on the ambient side of the envelope. Two ways of the PCM distribution in thermal insulation were also considered. The results of simulations were presented for conditions corresponding to the mean summer and winter seasons in Warsaw. It was found that thermal radiation plays an important role in heat transfer through thermal insulation layer of the wall while the presence of the PCM in it significantly contributes to damping of temperature fluctuations and a decrease in heat fluxes flowing into or lost by the interior of the building. The similar effect was observed for a decrease in emissivity of the microcapsules containing PCM.

  12. Thermal insulation product for insulation, especially in nuclear power engineering, and method of its production

    International Nuclear Information System (INIS)

    Veselovsky, P.; Zink, S.; Balacek, P.; Mares, I.

    1989-01-01

    The insulation consists of a sewn fabric cover made of inorganic fibers, in which the fiber filling is reinforced mechanically by dense point interweaving. The inorganic fibers, 1 to 5 μm in diameter, consist of min. 97 wt.% mixture of aluminium and silicon oxides in the vitreous state. The fibers making up the cover consist of min. 95% silicon, aluminium, calcium, magnesium and boron oxides in the vitreous state; the rest can consist of alloy steel fibres. The bulk density of the insulation is 70 to 150 kg/m 3 . The product is highly resistant to temperature and to the action of chemicals, water, and acid and alkaline deactivation solutions. Its manufacture is fast and undemanding. It is designed for thermal insulation of pipes, tanks and valves in nuclear power plants. (M.D.). 2 figs

  13. THERMAL INSULATION PROPERTIES RESEARCH OF THE COMPOSITE MATERIAL WATER GLASS–GRAPHITE MICROPARTICLES

    Directory of Open Access Journals (Sweden)

    V. A. Gostev

    2014-05-01

    Full Text Available Research results for the composite material (CM water glass–graphite microparticles with high thermal stability and thermal insulation properties are given. A composition consisting of graphite (42 % by weight, water glass Na2O(SiO2n (50% by weight and the hardener - sodium silicofluoric Na2SiF6 (8% by weight. Technology of such composition receipt is suggested. Experimental samples of the CM with filler particles (graphite and a few microns in size were obtained. This is confirmed by a study of samples by X-ray diffraction and electron microscopy. The qualitative and quantitative phase analysis of the CM structure is done. Load limit values leading to the destruction of CM are identified. The character of the rupture surface is detected. Numerical values of specific heat and thermal conductivity are defined. Dependence of the specific heat capacity and thermal conductivity on temperature at monotonic heating is obtained experimentally. Studies have confirmed the increased thermal insulation properties of the proposed composition. CM with such characteristics can be recommended as a coating designed to reduce heat losses and resistant to high temperatures. Due to accessibility and low cost of its components the proposed material can be produced on an industrial scale.

  14. Thermal insulation layer for the vacuum containers of a thermonuclear device

    International Nuclear Information System (INIS)

    Nishikawa, Masana; Yamada, Masao; Kameari, Akihisa; Niikura, Setsuo.

    1980-01-01

    Purpose: To prevent temperature rise of a thermal insulation layer for a vacuum container of a thermonuclear device higher than allowable value when irradiated by neutron by constructing the layer of a cooling unit in thermal insulation material. Constitution: A metal plate attached with cooling pipes is buried in a thermal insulation material forming a thermal insulation layer to form the layer provided between a vacuum container of a thermonuclear device and a shield. (Yoshihara, H.)

  15. Workshop on technical assessment of industrial thermal insulation materials: summary

    International Nuclear Information System (INIS)

    Peterson, S.

    1976-07-01

    Over 80 participants representing 50 organizations met to discuss the report, Industrial Thermal Insulation--An Assessment, ORNL/TM-5283. Presentations on the performance of available materials, economic considerations, and measurement problems were followed by discussion. A final wrap-up session concluded that the report was valuable in pointing the direction for needed effort in the area, confirmed the indicated actions needed to further industrial application of insulation, and called for future meetings to continue the dialogue between the various facets of the industry

  16. Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

    International Nuclear Information System (INIS)

    Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

    2014-01-01

    The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human–robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as α f + ξ f and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, α f + ξ f has a non-linear dependence on temperature and varies from 6.0 × 10 −6  °C −1 (20 °C) to 10.6 × 10 −6  °C −1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C. (paper)

  17. Enhancing thermal reliability of fiber-optic sensors for bio-inspired applications at ultra-high temperatures

    Science.gov (United States)

    Kang, Donghoon; Kim, Heon-Young; Kim, Dae-Hyun

    2014-07-01

    The rapid growth of bio-(inspired) sensors has led to an improvement in modern healthcare and human-robot systems in recent years. Higher levels of reliability and better flexibility, essential features of these sensors, are very much required in many application fields (e.g. applications at ultra-high temperatures). Fiber-optic sensors, and fiber Bragg grating (FBG) sensors in particular, are being widely studied as suitable sensors for improved structural health monitoring (SHM) due to their many merits. To enhance the thermal reliability of FBG sensors, thermal sensitivity, generally expressed as αf + ξf and considered a constant, should be investigated more precisely. For this purpose, the governing equation of FBG sensors is modified using differential derivatives between the wavelength shift and the temperature change in this study. Through a thermal test ranging from RT to 900 °C, the thermal sensitivity of FBG sensors is successfully examined and this guarantees thermal reliability of FBG sensors at ultra-high temperatures. In detail, αf + ξf has a non-linear dependence on temperature and varies from 6.0 × 10-6 °C-1 (20 °C) to 10.6 × 10-6 °C-1 (650 °C). Also, FBGs should be carefully used for applications at ultra-high temperatures due to signal disappearance near 900 °C.

  18. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Cavaignac, A.L.O. [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Lima, R.J.C., E-mail: ricardo.lima.ufma@gmail.com [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Façanha Filho, P.F. [Centro de Ciências Sociais, Saúde e Tecnologia, Universidade Federal do Maranhão, Imperatriz, MA 65900-410 (Brazil); Moreno, A.J.D. [Coordenação de Ciências Naturais, Universidade Federal do Maranhão, Bacabal, MA 65700-000 (Brazil); Freire, P.T.C. [Departamento de Física, Universidade Federal do Ceará, Fortaleza, CE 60455-760 (Brazil)

    2016-03-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  19. High-temperature Raman study of L-alanine, L-threonine and taurine crystals related to thermal decomposition

    International Nuclear Information System (INIS)

    Cavaignac, A.L.O.; Lima, R.J.C.; Façanha Filho, P.F.; Moreno, A.J.D.; Freire, P.T.C.

    2016-01-01

    In this work high-temperature Raman spectra are used to compare temperature dependence of the lattice mode wavenumber of L-alanine, L-threonine and taurine crystals. Anharmonic effects observed are associated with intermolecular N-H· · ·O hydrogen bond that plays an important role in thermal decomposition process of these materials. Short and strong hydrogen bonds in L-alanine crystal were associated with anharmonic effects in lattice modes leading to low thermal stability compared to taurine crystals. Connection between thermal decomposition process and anharmonic effects is furnished for the first time.

  20. Requirements for thermal insulation on prestressed concrete reactor vessels

    International Nuclear Information System (INIS)

    Neylan, A.J.; Wistrom, J.D.

    1979-01-01

    During the past decade, extensive design, construction, and operating experience on concrete pressure vessels for gas-cooled reactor applications has accumulated. Excellent experience has been obtained to date on the structural components (concrete, prestressing systems, liners, penetrations, and closures) and the thermal insulation. Three fundamentally different types of insulation systems have been employed to ensure the satisfactory performance of this component, which is critical to the overall success of the prestressed concrete reactor vessel (PCRV). Although general design criteria have been published, the requirements for design, materials, and construction are not rigorously addressed in any national or international code. With the more onerous design conditions being imposed by advanced reactor systems, much greater attention has been directed to advance the state of the art of insulation systems for PCRVs. This paper addresses some of the more recent developments in this field being performed by General Atomic Company and others. (author)

  1. Thermal Properties of Algerian Diatomite, Study of the Possibility to Its Use in the Thermal Insulation

    Science.gov (United States)

    Hamdi, Boualem; Hamdi, Safia

    The chemical and physical properties of a Algerian diatomite were given before and after heat treatment and chemical with an aim of a use in the heat insulation of constructions. The preliminary results obtained showed that this material is extremely porous (porosity >70 %), characterized of a low density and a very low thermal conductivity. These promising properties support the use of this local material in the thermal insulation.

  2. Thermal decomposition of polystyrene in the high temperature fabrication technology of hollow microspheres. Revision 1

    International Nuclear Information System (INIS)

    Dorogotovtsev, V.M.; Akunets, A.A.; Merkuliev, Y.A.; Turivnoy, A.P.

    1997-01-01

    The degree and nature of polymer degradation that occurs in the high temperature microshell formation process developed at the Lebedev Physical Institute has been examined experimentally. We find that significant mass degradation occurs during the final stages of shell formation. This manifests itself both in terms of mass loss and molecular weight degradation as measured by gel permeation chromatography. This decrease in the molecular weight may be in part responsible for the relatively fragile nature of the shells produced by this high temperature process. 9 refs., 6 figs., 2 tabs

  3. Comparative transcriptome profiling of a thermal resistant vs. sensitive silkworm strain in response to high temperature under stressful humidity condition.

    Directory of Open Access Journals (Sweden)

    Wenfu Xiao

    Full Text Available Thermotolerance is important particularly for poikilotherms such as insects. Understanding the mechanisms by which insects respond to high temperatures can provide insights into their adaptation to the environment. Therefore, in this study, we performed a transcriptome analysis of two silkworm strains with significantly different resistance to heat as well as humidity; the thermo-resistant strain 7532 and the thermos-sensitive strain Knobbed. We identified in total 4,944 differentially expressed genes (DEGs using RNA-Seq. Among these, 4,390 were annotated and 554 were novel. Gene Ontology (GO analysis of 747 DEGs identified between RT_48h (Resistant strain with high-temperature Treatment for 48 hours and ST_48h (Sensitive strain with high-temperature Treatment for 48 hours showed significant enrichment of 12 GO terms including metabolic process, extracellular region and serine-type peptidase activity. Moreover, we discovered 12 DEGs that may contribute to the heat-humidity stress response in the silkworm. Our data clearly showed that 48h post-exposure may be a critical time point for silkworm to respond to high temperature and humidity. These results provide insights into the genes and biological processes involved in high temperature and humidity tolerance in the silkworm, and advance our understanding of thermal tolerance in insects.

  4. Technology of Double Thermal Insulation for the Repair and Energy Optimization of Existing Thermal Insulation Composite Systems

    Science.gov (United States)

    Belániová, Barbora; Antošová, Naďa

    2017-06-01

    The theme of improvement thermal proprieties of external cladding according to the New EU Directive is still a hot topic, which needs to be answered necessarily till December 2020. Maintenance and repair of existing ETICS became to also an actual open theme in search solutions for existing constructions. The aim of the research in this review is to analyze influence of layers the alternative thermal materials in technology "double thermal insulation". Humidity and temperature conditions will be further examined in connection with the development and colonization of microorganisms on surface construction.

  5. Quantitative analysis of silica aerogel-based thermal insulation coatings

    DEFF Research Database (Denmark)

    Kiil, Søren

    2015-01-01

    containing intact hollow glass or polymer spheres showed that silica aerogel particles are more efficient in an insulation coating than hollow spheres. In a practical (non-ideal) comparison, the ranking most likely cannot be generalized. A parameter study demonstrates how the model can be used, qualitatively......A mathematical heat transfer model for a silica aerogel-based thermal insulation coating was developed. The model can estimate the thermal conductivity of a two-component (binder-aerogel) coating with potential binder intrusion into the nano-porous aerogel structure. The latter is modelled using...... a so-called core–shell structure representation. Data from several previous experimental investigations with silica aerogels in various binder matrices were used for model validation. For some relevant cases with binder intrusion, it was possible to obtain a very good agreement between simulations...

  6. High-Temperature Electrical Insulation Behavior of Alumina Films Prepared at Room Temperature by Aerosol Deposition and Influence of Annealing Process and Powder Impurities

    Science.gov (United States)

    Schubert, Michael; Leupold, Nico; Exner, Jörg; Kita, Jaroslaw; Moos, Ralf

    2018-04-01

    Alumina (Al2O3) is a widely used material for highly insulating films due to its very low electrical conductivity, even at high temperatures. Typically, alumina films have to be sintered far above 1200 °C, which precludes the coating of lower melting substrates. The aerosol deposition method (ADM), however, is a promising method to manufacture ceramic films at room temperature directly from the ceramic raw powder. In this work, alumina films were deposited by ADM on a three-electrode setup with guard ring and the electrical conductivity was measured between 400 and 900 °C by direct current measurements according to ASTM D257 or IEC 60093. The effects of film annealing and of zirconia impurities in the powder on the electrical conductivity were investigated. The conductivity values of the ADM films correlate well with literature data and can even be improved by annealing at 900 °C from 4.5 × 10-12 S/cm before annealing up to 5.6 × 10-13 S/cm after annealing (measured at 400 °C). The influence of zirconia impurities is very low as the conductivity is only slightly elevated. The ADM-processed films show a very good insulation behavior represented by an even lower electrical conductivity than conventional alumina substrates as they are commercially available for thick-film technology.

  7. Lattice Thermal Conductivity of Ultra High Temperature Ceramics ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, John W.; Murray, Daw S.; Bauschlicher, Charles W., Jr.

    2011-01-01

    Atomistic Green-Kubo simulations are performed to evaluate the lattice thermal conductivity for single crystals of the ultra high temperature ceramics ZrB2 and HfB2 for a range of temperatures. Recently developed interatomic potentials are used for these simulations. Heat current correlation functions show rapid oscillations which can be identified with mixed metal-Boron optical phonon modes. Agreement with available experimental data is good.

  8. 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.

  9. Preliminary data evaluation for thermal insulation characterization testing

    International Nuclear Information System (INIS)

    DeClue, J.F.; Moses, S.D.; Tollefson, D.A.

    1991-01-01

    The purpose of Thermal Insulation Characterization Testing is to provide physical data to support certain assumptions and calculational techniques used in the criticality safety calculations in Section 6 of the Safety Analysis Reports for Packaging (SARPs) for drum-type packaging for Department of Energy's (DOE) Oak Ridge Y-12 Plant, managed by Martin Marietta Energy Systems, Inc. Results of preliminary data evaluation regarding the fire-test condition reveal that realistic weight loss consideration and residual material characterization in developing calculational models for the hypothetical accident condition is necessary in order to prevent placement of unduly conservative restrictions on shipping requirements as a result of overly conservative modeling. This is particularly important for fast systems. Determination of the geometric arrangement of residual material is of secondary importance. Both the methodology used to determine the minimum thermal insulation mass remaining after the fire test and the treatment of the thermal insulation in the criticality safety calculational models requires additional evaluation. Specific testing to be conducted will provide experimental data with which to validate the mass estimates and calculational modeling techniques for extrapolation to generic drum-type containers

  10. Role of oxides and porosity on high temperature oxidation of liquid fuelled HVOF thermal sprayed Ni50Cr coatings

    OpenAIRE

    Song, B.; Bai, M.; Voisey, K.T.; Hussain, Tanvir

    2017-01-01

    High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid fuelled high velocity oxy-fuel (HVOF) thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using...

  11. Theoretical Research on Thermal Shock Resistance of Ultra-High Temperature Ceramics Focusing on the Adjustment of Stress Reduction Factor

    Directory of Open Access Journals (Sweden)

    Daining Fang

    2013-02-01

    Full Text Available The thermal shock resistance of ceramics depends on not only the mechanical and thermal properties of materials, but also the external constraint and thermal condition. So, in order to study the actual situation in its service process, a temperature-dependent thermal shock resistance model for ultra-high temperature ceramics considering the effects of the thermal environment and external constraint was established based on the existing theory. The present work mainly focused on the adjustment of the stress reduction factor according to different thermal shock situations. The influences of external constraint on both critical rupture temperature difference and the second thermal shock resistance parameter in either case of rapid heating or cooling conditions had been studied based on this model. The results show the necessity of adjustment of the stress reduction factor in different thermal shock situations and the limitations of the applicable range of the second thermal shock resistance parameter. Furthermore, the model was validated by the finite element method.

  12. The Effect of High Temperatures on the Effective Thermal Conductivity of Concrete

    International Nuclear Information System (INIS)

    Weidenfeld, G.; Aharon, G.; Hochbaum, I.

    2002-01-01

    Concrete thermal conductivity is an important property for thermal analysis of nuclear accidents.Concrete compositions include water,sand,cement and aggregates of various kinds and combinations.Values of concrete's thermal conductivity for some different compositions can be found in the literature[1]but since the material composition and its temperature significantly affect this property,the exact value of a specific composition should be measured

  13. Thermal resistances of air in cavity walls and their effect upon the thermal insulation performance

    Energy Technology Data Exchange (ETDEWEB)

    Bekkouche, S.M.A.; Cherier, M.K.; Hamdani, M.; Benamrane, N. [Application of Renewable Energies in Arid and Semi Arid Environments /Applied Research Unit on Renewable Energies/ EPST Development Center of Renewable Energies, URAER and B.P. 88, ZI, Gart Taam Ghardaia (Algeria); Benouaz, T. [University of Tlemcen, BP. 119, Tlemcen R.p. 13000 (Algeria); Yaiche, M.R. [Development Center of Renewable Energies, CDER and B.P 62, 16340, Route de l' Observatoire, Bouzareah, Algiers (Algeria)

    2013-07-01

    The optimum thickness in cavity walls in buildings is determined under steady conditions; the heat transfer has been calculated according to ISO 15099:2003. Two forms of masonry units are investigated to conclude the advantage of high thermal emissivity. The paper presents also some results from a study of the thermal insulation performance of air cavities bounded by thin reflective material layer 'eta = 0.05'. The results show that the most economical cavity configuration depends on the thermal emissivity and the insulation material used.

  14. Thermal expansion and phase transformation studies on some materials by high temperature x-ray powder diffractometry

    International Nuclear Information System (INIS)

    Rajagopalan, S.; Kutty, K.V.G.; Jajoo, H.K.; Ananthakrishnan, S.K.; Asurvatharaman, R.

    1988-01-01

    A high temperature chamber based on electrical resistance heating has been integrated to an existing x-ray powder diffractometer. The system is capable of going upto 2500degC at programmed rates of heating. Temperature measurement is carried out by means by Pt/Rh or W/Re thermocouples or by optical pyrometry depending upon the temperature range. Provision exists for performing high temperature x-ray diffractometry in vacuum or in a gaseous atmosphere of low x-ray absorption. The x-ray optical alignment has been ensured by accurately measuring the unit cell lengths of x-ray diffraction standards like silicon and tungsten. The thermocouples have been calibrated within the system by monitoring the melting points of gold and silver. The well characterized transformation of zirconia from the monoclinic to tetragonal structure occuring around 1100degC has been satisfactorily reproduced . The high temperature phase transitions in some rare earth oxides have been studi ed. lattice parameter measurements on a variety of materials as a function of temperature upto 1500degC have been carried out and the data found to be in agreement with the literature values. From the measured lattice parameter values, percentage thermal expansion and coefficients of thermal expansion have been calculated for many substances from room temperature to 15000degC. (author). 20 refs., 9 figs

  15. A Numerical Study on the Heat Transfer Characteristics of a Solar Thermal Receiver with High-temperature Heat Pipes

    International Nuclear Information System (INIS)

    Park, Young Hark; Jung, Eui Guk; Boo, Joon Hong

    2007-01-01

    A numerical analysis was conducted to predict the heat transfer characteristics of a solar receiver which is subject to very high heat fluxes and temperatures for solar thermal applications. The concentration ratio of the solar receiver ranges from 200 to 1000 and the concentrated heat is required to be transported to a certain distance for specific applications. The study deals with a solar receiver incorporating high-temperature sodium heat pipe as well as typical one that employs a molten-salt circulation loop. The isothermal characteristics in the receiver section is of major concern. The diameter of the solar thermal receiver was 120 mm and the length was 400 mm. For the molten-salt circulation type receiver, 48 axial channels of the same dimensions were attached to the outer wall of the receiver with even spacing in the circumferential direction. The molten salt fed through the channels by forced convection using a special pump. For the heat pipe receiver, the channels are changed to high-temperature sodium heat pipes. Commercial softwares were employed to deal with the radiative heat transfer inside the receiver cavity and the convection heat transfer along the channels. The numerical results are compared and analyzed from the view point of high-temperature solar receiver

  16. Two-dimensional thermal analysis of liquid hydrogen tank insulation

    Energy Technology Data Exchange (ETDEWEB)

    Babac, Gulru; Sisman, Altug [Istanbul Technical University, Energy Institute, Ayazaga campus, 34469 Maslak, Istanbul (Turkey); Cimen, Tolga [Jaguar and Landrover, Banbury Road, Gaydon, Warwick CV35 0RR (United Kingdom)

    2009-08-15

    Liquid hydrogen (LH{sub 2}) storage has the advantage of high volumetric energy density, while boil-off losses constitute a major disadvantage. To minimize the losses, complicated insulation techniques are necessary. In general, Multi Layer Insulation (MLI) and a Vapor-Cooled Shield (VCS) are used together in LH{sub 2} tanks. In the design of an LH{sub 2} tank with VCS, the main goal is to find the optimum location for the VCS in order to minimize heat leakage. In this study, a 2D thermal model is developed by considering the temperature dependencies of the thermal conductivity and heat capacity of hydrogen gas. The developed model is used to analyze the effects of model considerations on heat leakage predictions. Furthermore, heat leakage in insulation of LH{sub 2} tanks with single and double VCS is analyzed for an automobile application, and the optimum locations of the VCS for minimization of heat leakage are determined for both cases. (author)

  17. Thermal Analysis of Low Layer Density Multilayer Insulation Test Results

    Science.gov (United States)

    Johnson, Wesley L.

    2011-01-01

    Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density, as widely reported in the literature. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test coupons for calorimeter testing. These coupons were configured to allow for the layer density to be varied from 0.5 to 2.6 layer/mm. The coupon testing was completed using the cylindrical Cryostat-l00 apparatus by the Cryogenics Test Laboratory at Kennedy Space Center. The results show the properties of the insulation as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals a minimum layer density; however, the value is higher than predicted. Additionally, the data show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. Historically this spacing has not been taken into account as thermal performance was calculated as a function of pressure and temperature only; however the recent testing shows that the data is dependent on the Knudsen number which takes into account pressure, temperature, and layer spacing. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

  18. Thermal Insulating Concrete Wall Panel Design for Sustainable Built Environment

    Science.gov (United States)

    Zhou, Ao; Wong, Kwun-Wah

    2014-01-01

    Air-conditioning system plays a significant role in providing users a thermally comfortable indoor environment, which is a necessity in modern buildings. In order to save the vast energy consumed by air-conditioning system, the building envelopes in envelope-load dominated buildings should be well designed such that the unwanted heat gain and loss with environment can be minimized. In this paper, a new design of concrete wall panel that enhances thermal insulation of buildings by adding a gypsum layer inside concrete is presented. Experiments have been conducted for monitoring the temperature variation in both proposed sandwich wall panel and conventional concrete wall panel under a heat radiation source. For further understanding the thermal effect of such sandwich wall panel design from building scale, two three-story building models adopting different wall panel designs are constructed for evaluating the temperature distribution of entire buildings using finite element method. Both the experimental and simulation results have shown that the gypsum layer improves the thermal insulation performance by retarding the heat transfer across the building envelopes. PMID:25177718

  19. Design, Fabrication, Test Report of the Material Capsule(08M-10K) with Double Thermal Media for High-temperature Irradiation

    International Nuclear Information System (INIS)

    Cho, Man Soon; Choo, K. N.; Kang, Y. H.; Sohn, J. M.; Shin, Y. T.; Park, S. J.; Kim, B. G.; Oh, S. Y.

    2010-01-01

    To overcome the restriction of the irradiation test at a high temperature of the existing material capsule with Al thermal media, a capsule suitable for the irradiation at the high temperature was developed and the performance test was undertaken. The 08M-10K capsule was designed and fabricated as that with double thermal media to verify the structural and external integrity in the high-temperature irradiation higher than 500 .deg. C. The thermal performance test was undertaken at the out-pile test facility, and the soundness of the double thermal media was confirmed with the naked eye after disassembling the capsule. Though the temperatures of the specimens reach 500±20 .deg. C as a result maintaining the capsule during 5 hours after setting the specimens temperatures in the target range, the high-temperature thermal media with double structure was confirmed to maintain the soundness. And the specimens and the thermal media were heated to 600 .deg. C for about 3 minutes, but the thermal media were maintained sound. Especially, the Al thermal media were heated for 5 hours in range of 500±20 .deg. C and for 3 minutes at the temperature of 600 .deg. C. However, the thermal media were confirmed to maintain the soundness. Whether a capsule has only Al thermal media or the high-temperature thermal media with double structure, any capsule can be used in the range of 500±20 .deg. C as the result of this experiment maintaining the specimens high-temperature

  20. High-temperature thermal conductivity of uranium chromite and uranium niobate

    International Nuclear Information System (INIS)

    Fedoseev, D.V.; Varshavskaya, I.G.; Lavrent'ev, A.V.; Oziraner, S.N.; Kuznetsova, D.G.

    1979-01-01

    The technique of determining thermal conductivity coefficient of uranium niobate and uranium chromite on heating with laser radiation is described. Determined is the coefficient of free-convective heat transfer (with provision for a conduction component) by means of a standard specimen. The thermal conductivity coefficients of uranium chromite and niobate were measured in the 1300-1700 K temperature range. The results are presented in a diagram form. It has been calculated, that the thermal conductivity coefficient for uranium niobate specimens is greater in comparison with uranium chromite specimens. The thermal conductivity coefficients of the materials mentioned depend on temperature very slightly. Thermal conductivity of the materials considerably depends on their porosity. The specimens under investigation were fabricated by the pressing method and had the following porosity: uranium chromite - 30 %, uranium niobate - 10 %. Calculation results show, that thermal conductivity of dense uranium chromite is higher than thermal conductivity of dense uranium niobate. The experimental error equals approximately 20 %, that is mainly due to the error of measuring the temperature equal to +-25 deg, with a micropyrometer

  1. A High Temperature Kinetic Study for the Thermal Unimolecular Decomposition of Diethyl Carbonate

    KAUST Repository

    Alabbad, Mohammed

    2017-07-08

    Thermal unimolecular decomposition of diethyl carbonate (DEC) was investigated in a shock tube by measuring ethylene concentration with a CO2 gas laser over 900 - 1200 K and 1.2 – 2.8 bar. Rate coefficients were extracted using a simple kinetic scheme comprising of thermal decomposition of DEC as initial step followed by rapid thermal decomposition of the intermediate ethyl-hydrogen-carbonate. Our results were further analysed using ab initio and master equation calculations to obtain pressure- and temperature- dependence of rate coefficients. Similar to alkyl esters, unimolecular decomposition of DEC is found to undergo six-center retro-ene elimination of ethylene in a concerted manner.

  2. A High Temperature Kinetic Study for the Thermal Unimolecular Decomposition of Diethyl Carbonate

    KAUST Repository

    Alabbad, Mohammed; Giri, Binod; Szőri, Milan; Viskolcz, Bé la; Farooq, Aamir

    2017-01-01

    Thermal unimolecular decomposition of diethyl carbonate (DEC) was investigated in a shock tube by measuring ethylene concentration with a CO2 gas laser over 900 - 1200 K and 1.2 – 2.8 bar. Rate coefficients were extracted using a simple kinetic scheme comprising of thermal decomposition of DEC as initial step followed by rapid thermal decomposition of the intermediate ethyl-hydrogen-carbonate. Our results were further analysed using ab initio and master equation calculations to obtain pressure- and temperature- dependence of rate coefficients. Similar to alkyl esters, unimolecular decomposition of DEC is found to undergo six-center retro-ene elimination of ethylene in a concerted manner.

  3. The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

    NARCIS (Netherlands)

    van Lopik, J.H.; Hartog, N.; Zaadnoordijk, Willem Jan

    The efficiency of heat recovery in high-temperature (>60 °C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity

  4. Sprayable Aerogel Bead Compositions With High Shear Flow Resistance and High Thermal Insulation Value

    Science.gov (United States)

    Ou, Danny; Trifu, Roxana; Caggiano, Gregory

    2013-01-01

    A sprayable aerogel insulation has been developed that has good mechanical integrity and lower thermal conductivity than incumbent polyurethane spray-on foam insulation, at similar or lower areal densities, to prevent insulation cracking and debonding in an effort to eliminate the generation of inflight debris. This new, lightweight aerogel under bead form can be used as insulation in various thermal management systems that require low mass and volume, such as cryogenic storage tanks, pipelines, space platforms, and launch vehicles.

  5. Thermal Stir Welding of High Strength and High Temperature Alloys for Aerospace Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The Keystone and MSU team propose to demonstrate the feasibility of solid-state joining high strength and temperature alloys utilizing the Thermal Stir Welding...

  6. High-temperature stability of yttria-stabilized zirconia thermal barrier ...

    Indian Academy of Sciences (India)

    temperature drop was found to increase with the coating thickness of YSZ. The coatings ... thermal barrier coating system on niobium alloys for supersonic vehicles. .... Voltage (V). 75 ..... However, distribution of the other elements; such as Ni,.

  7. Advanced high-temperature thermal energy storage media for industrial applications

    Science.gov (United States)

    Claar, T. D.; Waibel, R. T.

    1982-02-01

    An advanced thermal energy storage media concept based on use of carbonate salt/ceramic composite materials is being developed for industrial process and reject heat applications. The composite latent/sensible media concept and its potential advantages over state of the art latent heat systems is described. Media stability requirements, on-going materials development efforts, and planned thermal energy storage (TES) performance evaluation tests are discussed.

  8. Thermal and rotational effect on giant dipole resonances in rotating nuclei at high temperature

    International Nuclear Information System (INIS)

    Sugawara-Tanabe, Kazuko; Tanabe, Kosai.

    1986-01-01

    Microscopic calculations are carried out for the giant dipole resonances excited on the thermal high spin states in 162 Er and 166 Er based on the thermal linear response theory with realistic forces and large single-particle space. The dynamical strength function is compared with the experimental γ-ray absorption cross section. The general trend that the resonance energy decreases and the resonance width increases with increasing angular momentum and temperature is well reproduced by the calculations. (author)

  9. New WC-Cu thermal barriers for fusion applications: High temperature mechanical behaviour

    Science.gov (United States)

    Tejado, E.; Dias, M.; Correia, J. B.; Palacios, T.; Carvalho, P. A.; Alves, E.; Pastor, J. Y.

    2018-01-01

    The combination of tungsten carbide and copper as a thermal barrier could effectively reduce the thermal mismatch between tungsten and copper alloy, which are proposed as base armour and heat sink, respectively, in the divertor of future fusion reactors. Furthermore, since the optimum operating temperature windows for these divertor materials do not overlap, a compatible thermal barrier interlayer between them is required to guarantee a smooth thermal transition, which in addition may mitigate radiation damage. The aim of this work is to study the thermo-mechanical properties of WC-Cu cermets fabricated by hot pressing. Focus is placed on the temperature effect and composition dependence, as the volume fraction of copper varies from 25 to 50 and 75 vol%. To explore this behaviour, fracture experiments are performed within a temperature range from room temperature to 800 °C under vacuum. In addition, elastic modulus and thermal expansion coefficient are estimated from these tests. Results reveal a strong dependence of the performance on temperature and on the volume fraction of copper and, surprisingly, a slight percent of Cu (25 vol%) can effectively reduce the large difference in thermal expansion between tungsten and copper alloy, which is a critical point for in service applications. The thermal performance of these materials, together with their mechanical properties could indeed reduce the heat transfer from the PFM to the underlying element while supporting the high thermal stresses of the joint. Thus, the presence of these cermets could allow the reactor to operate above the ductile to brittle transition temperature of tungsten, without compromising the underlying materials.

  10. Thermal conductivities and conduction mechanisms of Sb-Te Alloys at high temperatures

    International Nuclear Information System (INIS)

    Lan, Rui; Endo, Rie; Kobayashi, Yoshinao; Susa, Masahiro; Kuwahara, Masashi

    2011-01-01

    Sb-Te alloys have drawn much attention due to its application in phase change memory as well as the unique properties as chalcogenide. In this work, the thermal conductivities of Sb-x mol%Te alloys (x = 14, 25, 44, 60, 70, and 90) have been measured by the hot strip method from room temperature up to temperature just below the respective melting points. For the intermetallic compound Sb 2 Te 3 (x = 60), the thermal conductivity decreases up to approximately 600 K and then increases. For other Sb-x mol%Te alloys where x > 60, the thermal conductivities of the alloys decrease with increasing temperature. In contrast, for x < 60, the thermal conductivities of the alloys keep roughly constant up to approximately 600 K and then increase with increasing temperature. It is proposed that free electron dominates the heat transport below 600 K, and ambipolar diffusion also contributes to the increase in the thermal conductivity at higher temperatures. The prediction equation from temperature and chemical composition has been proposed for thermal conductivities of Sb-Te alloys.

  11. An investigation on the effects of phase change material on material components used for high temperature thermal energy storage system

    Science.gov (United States)

    Kim, Taeil; Singh, Dileep; Zhao, Weihuan; Yua, Wenhua; France, David M.

    2016-05-01

    The latent heat thermal energy storage (LHTES) systems for concentrated solar power (CSP) plants with advanced power cycle require high temperature phase change materials (PCMs), Graphite foams with high thermal conductivity to enhance the poor thermal conductivity of PCMs. Brazing of the graphite foams to the structural metals of the LHTES system could be a method to assemble the system and a method to protect the structural metals from the molten salts. In the present study, the LHTES prototype capsules using MgCl2-graphite foam composites were assembled by brazing and welding, and tested to investigate the corrosion attack of the PCM salt on the BNi-4 braze. The microstructural analysis showed that the BNi-4 braze alloy can be used not only for the joining of structure alloy to graphite foams but also for the protecting of structure alloy from the corrosion by PCM.

  12. Partitioning planning studies: Preliminary evaluation of metal and radionuclide partitioning the high-temperature thermal treatment systems

    International Nuclear Information System (INIS)

    Liekhus, K.; Grandy, J.; Chambers, A.

    1997-03-01

    A preliminary study of toxic metals and radionuclide partitioning during high-temperature processing of mixed waste has been conducted during Fiscal Year 1996 within the Environmental Management Technology Evaluation Project. The study included: (a) identification of relevant partitioning mechanisms that cause feed material to be distributed between the solid, molten, and gas phases within a thermal treatment system; (b) evaluations of existing test data from applicable demonstration test programs as a means to identify and understand elemental and species partitioning; and, (c) evaluation of theoretical or empirical partitioning models for use in predicting elemental or species partitioning in a thermal treatment system. This preliminary study was conducted to identify the need for and the viability of developing the tools capable of describing and predicting toxic metals and radionuclide partitioning in the most applicable mixed waste thermal treatment processes. This document presents the results and recommendations resulting from this study that may serve as an impetus for developing and implementing these predictive tools

  13. Partitioning planning studies: Preliminary evaluation of metal and radionuclide partitioning the high-temperature thermal treatment systems

    Energy Technology Data Exchange (ETDEWEB)

    Liekhus, K.; Grandy, J.; Chambers, A. [and others

    1997-03-01

    A preliminary study of toxic metals and radionuclide partitioning during high-temperature processing of mixed waste has been conducted during Fiscal Year 1996 within the Environmental Management Technology Evaluation Project. The study included: (a) identification of relevant partitioning mechanisms that cause feed material to be distributed between the solid, molten, and gas phases within a thermal treatment system; (b) evaluations of existing test data from applicable demonstration test programs as a means to identify and understand elemental and species partitioning; and, (c) evaluation of theoretical or empirical partitioning models for use in predicting elemental or species partitioning in a thermal treatment system. This preliminary study was conducted to identify the need for and the viability of developing the tools capable of describing and predicting toxic metals and radionuclide partitioning in the most applicable mixed waste thermal treatment processes. This document presents the results and recommendations resulting from this study that may serve as an impetus for developing and implementing these predictive tools.

  14. Stability analysis of the high temperature thermal pebble bed nuclear reactor concept

    International Nuclear Information System (INIS)

    Vondy, D.R.

    1981-02-01

    A study was made of the stability of the high temperature gas-cooled pebble bed core against xenon-driven oscillation. This generic study indicated that a core as large as 3000 MW(t) could be stable. Several aspects present a challenge to analysis including the void space above the pebble bed, the effects of possible control rod configurations, and the temperature feedback contribution. Special methods of analysis were developed in this effort. Of considerable utility was the scheme of including an azimuthal buckling loss term in the neturon balance equations admitting direct solution of the first azimuthal harmonic for a core having azimuthal symmetry. This technique allows the linear stability analysis to be done solving two-dimensional (RZ) problems instead of three-dimensional problems. A scheme for removing the fundamental source contribution was also implemented to allow direct iteration toward the dominant harmonic solution, treating up to three dimensions with diffusion theory

  15. Experimental study on thermal interaction between a high-temperature molten jet and plates

    International Nuclear Information System (INIS)

    Sato, K.; Saito, M.; Furutani, A.; Isozaki, M.; Imahori, S.; Konishi, K.

    1994-01-01

    This paper summarizes the recent simulant experiments to study molten corium-structure interactions under postulated core disruptive accident (CDA) conditions in liquid-metal fast breeder reactors (LMFMRs). These experiments were conducted in the MELT-II facility generating high-temperature molten simulants by an induction heating technique. From a series of molten jet-structure interaction experiments, the effects of the solidified crust layer and molten layer on the erosion behavior were identified, and analytical models were developed to assess the structure erosion rate with and without crust formation. Especially, we revealed the inherent mitigation mechanism that when the molten oxide jet with high melting point falls down onto the structure plate, solidified crust of the oxide can significantly reduce the erosion rate. (author)

  16. Development of thermal mixing enhancement method for lower plenum of the High Temperature Test Facility

    Energy Technology Data Exchange (ETDEWEB)

    Gradecka, Malwina Joanna, E-mail: malgrad@gmail.com; Woods, Brian G., E-mail: brian.woods@oregonstate.edu

    2016-08-15

    Highlights: • Coolant mixing in lower plenum might be insufficient and pose operational issues. • Two mixing methods were developed to lower the coolant temperature variation. • The methods resulted with reduction of the temperature variation by 60% and 71%. - Abstract: The High Temperature Gas-cooled Reactor (HTGR) is one of the most mature Gen IV reactor concepts under development today. The High Temperature Test Facility (HTTF) at Oregon State University is a test facility that supports the R&D needs for HTGRs. This study focuses on the issue of helium mixing after the core section in the HTTF, the results of which are generally applicable in HTGRs. In the HTTF, hot helium jets at different temperatures are supposed to uniformly mix in the lower plenum (LP) chamber. However, the level of mixing is not sufficient to reduce the peak helium temperature before the hot jet impinges the LP structure, which can cause issues with structural materials and operational issues in the heat exchanger downstream. The maximum allowable temperature variation in the outlet duct connected to the lower plenum is defined as 40 K (±20 K from the average temperature), while the CFD simulations of this study indicate that the reference design suffers temperature variations in the duct as high as 100 K. To solve this issue, the installation of mixing-enhancing structures within the outlet duct were proposed and analyzed using CFD modeling. We show that using either an optimized “Kwiat” structure (developed in this study) or a motionless mixer installed in the outlet duct, the temperature variations can be brought dramatically, with acceptable increases in pressure drop. The optimal solution appears to be to install double motionless mixers with long blades in the outlet duct, which brings the temperature variation into the acceptable range (from 100 K down to 18 K), with a resulting pressure drop increase in the HTTF loop of 0.73 kPa (6% of total pressure drop).

  17. Development of thermal mixing enhancement method for lower plenum of the High Temperature Test Facility

    International Nuclear Information System (INIS)

    Gradecka, Malwina Joanna; Woods, Brian G.

    2016-01-01

    Highlights: • Coolant mixing in lower plenum might be insufficient and pose operational issues. • Two mixing methods were developed to lower the coolant temperature variation. • The methods resulted with reduction of the temperature variation by 60% and 71%. - Abstract: The High Temperature Gas-cooled Reactor (HTGR) is one of the most mature Gen IV reactor concepts under development today. The High Temperature Test Facility (HTTF) at Oregon State University is a test facility that supports the R&D needs for HTGRs. This study focuses on the issue of helium mixing after the core section in the HTTF, the results of which are generally applicable in HTGRs. In the HTTF, hot helium jets at different temperatures are supposed to uniformly mix in the lower plenum (LP) chamber. However, the level of mixing is not sufficient to reduce the peak helium temperature before the hot jet impinges the LP structure, which can cause issues with structural materials and operational issues in the heat exchanger downstream. The maximum allowable temperature variation in the outlet duct connected to the lower plenum is defined as 40 K (±20 K from the average temperature), while the CFD simulations of this study indicate that the reference design suffers temperature variations in the duct as high as 100 K. To solve this issue, the installation of mixing-enhancing structures within the outlet duct were proposed and analyzed using CFD modeling. We show that using either an optimized “Kwiat” structure (developed in this study) or a motionless mixer installed in the outlet duct, the temperature variations can be brought dramatically, with acceptable increases in pressure drop. The optimal solution appears to be to install double motionless mixers with long blades in the outlet duct, which brings the temperature variation into the acceptable range (from 100 K down to 18 K), with a resulting pressure drop increase in the HTTF loop of 0.73 kPa (6% of total pressure drop).

  18. Ultra-low power high temperature and radiation hard complementary metal-oxide-semiconductor (CMOS) silicon-on-insulator (SOI) voltage reference.

    Science.gov (United States)

    Boufouss, El Hafed; Francis, Laurent A; Kilchytska, Valeriya; Gérard, Pierre; Simon, Pascal; Flandre, Denis

    2013-12-13

    This paper presents an ultra-low power CMOS voltage reference circuit which is robust under biomedical extreme conditions, such as high temperature and high total ionized dose (TID) radiation. To achieve such performances, the voltage reference is designed in a suitable 130 nm Silicon-on-Insulator (SOI) industrial technology and is optimized to work in the subthreshold regime of the transistors. The design simulations have been performed over the temperature range of -40-200 °C and for different process corners. Robustness to radiation was simulated using custom model parameters including TID effects, such as mobilities and threshold voltages degradation. The proposed circuit has been tested up to high total radiation dose, i.e., 1 Mrad (Si) performed at three different temperatures (room temperature, 100 °C and 200 °C). The maximum drift of the reference voltage V(REF) depends on the considered temperature and on radiation dose; however, it remains lower than 10% of the mean value of 1.5 V. The typical power dissipation at 2.5 V supply voltage is about 20 μW at room temperature and only 75 μW at a high temperature of 200 °C. To understand the effects caused by the combination of high total ionizing dose and temperature on such voltage reference, the threshold voltages of the used SOI MOSFETs were extracted under different conditions. The evolution of V(REF) and power consumption with temperature and radiation dose can then be explained in terms of the different balance between fixed oxide charge and interface states build-up. The total occupied area including pad-ring is less than 0.09 mm2.

  19. Naturally cured foamed concrete with improved thermal insulation properties

    Directory of Open Access Journals (Sweden)

    Mashkin Nikolay

    2018-01-01

    Full Text Available The paper is dedicated to investigation on improvement of thermal insulation properties of non-autoclaved concrete by increasing aggregate stability of foamed concrete mixture. The study demonstrates influence of mineral admixtures on the foam stability index in the mortar mixture and on decrease of foamed concrete density and thermal conductivity. The effect of mineral admixtures on thermal conductivity properties of non-autoclaved concrete was assessed through different ways of their addition: to the foam and to the mortar mixture. The admixtures were milled up to the specific surface area of 300 and 600 m2/kg using an AГO-9 centrifugal attrition mill with continuous operation mode (Institute of Solid State Chemistry and Mechanochemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk. Laboratory turbulent foam concrete mixer was used to prepare foamed concrete. Thermal conductivity coefficient was defined by a quick method using “ИTП-MГ 4 “Zond” thermal conductivity meter in accordance with the regulatory documents. The impact of modifiers on the foam structure stability was defined using the foam stability index for the mortar mixture. The research demonstrated the increase in stability of porous structure of non-autoclaved concrete when adding wollastonite and diopside. Improvement of thermal and physical properties was demonstrated, the decrease of thermal conductivity coefficient reaches 0.069 W/(m×°C

  20. Thermal characteristic of sintered AgeCu nano-paste for high-temperature die-attach application

    International Nuclear Information System (INIS)

    Tan, Kim Seah; Cheong, Kuan Yew; Wong, Yew Hoong

    2015-01-01

    In this work, thermal characteristic of silver-copper (Ag-Cu) nano-paste that consists of a mixture of nano-sized Ag and Cu particles and organic compounds meant for high-temperature die-attach application is reported. The Ag-Cu nano-paste was sintered at 380 deg. C for 30 min without the need of applying external pressure and the effect of Cu loading (20-80 wt%) on the thermal properties was investigated in against of pure Ag nano-paste and pure Cu nano-paste. The results showed the specific heat of sintered Ag-Cu nano-paste was increased as the loading of Cu increased. For thermal conductivity and coefficient of thermal expansion (CTE) of sintered Ag-Cu nano-paste, a declining trend has been recorded with the increment of Cu loading. Overall, the sintered Ag-Cu nano-paste with 20 wt% of Cu loading has demonstrated the best combination of thermal conductivity (K) and CTE (α), which were 159 W/m K and 13 x 10 -6 /K, respectively. It has proven that there was a strong correlation between the amount of pores and thermal properties of the nano-paste. The ratio of K/α is a performance index (M), which has shown a higher value (12.2 x 10 6 W/m) than most of the commonly used die-attach systems. Finally, the Ag-Cu nano-paste has demonstrated a melting point of 955 deg. C, which can be proposed as an alternative high-temperature die-attach material

  1. High-temperature thermal storage systems for advanced solar receivers materials selections

    Science.gov (United States)

    Wilson, D. F.; Devan, J. H.; Howell, M.

    1990-01-01

    Advanced space power systems that use solar energy and Brayton or Stirling heat engines require thermal energy storage (TES) systems to operate continuously through periods of shade. The receiver storage units, key elements in both Brayton and Stirling systems, are designed to use the latent heat of fusion of phase-change materials (PCMs). The power systems under current consideration for near-future National Aeronautics and Space Administration space missions require working fluid temperatures in the 1100 to 1400 K range. The PCMs under current investigation that gave liquid temperatures within this range are the fluoride family of salts. However, these salts have low thermal conductivity, which causes large temperature gradients in the storage systems. Improvements can be obtained, however, with the use of thermal conductivity enhancements or metallic PCMs. In fact, if suitable containment materials can be found, the use of metallic PCMs would virtually eliminate the orbit associated temperature variations in TES systems. The high thermal conductivity and generally low volume change on melting of germanium and alloys based on silicon make them attractive for storage of thermal energy in space power systems. An approach to solving the containment problem, involving both chemical and physical compatibility, preparation of NiSi/NiSi2, and initial results for containment of germanium and NiSi/NiSi2, are presented.

  2. Selection of high temperature thermal energy storage materials for advanced solar dynamic space power systems

    Science.gov (United States)

    Lacy, Dovie E.; Coles-Hamilton, Carolyn; Juhasz, Albert

    1987-01-01

    Under the direction of NASA's Office of Aeronautics and Technology (OAST), the NASA Lewis Research Center has initiated an in-house thermal energy storage program to identify combinations of phase change thermal energy storage media for use with a Brayton and Stirling Advanced Solar Dynamic (ASD) space power system operating between 1070 and 1400 K. A study has been initiated to determine suitable combinations of thermal energy storage (TES) phase change materials (PCM) that result in the smallest and lightest weight ASD power system possible. To date the heats of fusion of several fluoride salt mixtures with melting points greater than 1025 K have been verified experimentally. The study has indicated that these salt systems produce large ASD systems because of their inherent low thermal conductivity and low density. It is desirable to have PCMs with high densities and high thermal conductivities. Therefore, alternate phase change materials based on metallic alloy systems are also being considered as possible TES candidates for future ASD space power systems.

  3. Thermal stability and high temperature polymorphism of topochemically-prepared Dion–Jacobson triple-layered perovskites

    Energy Technology Data Exchange (ETDEWEB)

    Guertin, Stephen L.; Josepha, Elisha A.; Montasserasadi, Dariush; Wiley, John B., E-mail: jwiley@uno.edu

    2015-10-25

    The thermal stability of six Dion–Jacobson-related triple layered perovskites, ACa{sub 2}Nb{sub 3}O{sub 10} (A = H, NH{sub 4}, Li, Na, K, CuCl), was explored to 1000 °C. Each compound was produced topochemically by low-temperature (<500 °C) ion exchange from RbCa{sub 2}Nb{sub 3}O{sub 10}. The thermal behavior of the series was examined by variable temperature X-ray powder diffraction experiments in tandem with thermogravimetric analysis and differential scanning calorimetry. Five of the species were found to be low temperature/metastable phases, decomposing below 900 °C, where the stability of the series decreased with decreasing interlayer cation size. The compounds, A = Li, Na, K, exhibited high temperature polymorphism, with a completely reversible transition evident for KCa{sub 2}Nb{sub 3}O{sub 10}. - Highlights: • Thermal stability of topochemically prepared triple-layered perovskites studied. • Clear correlation seen between stability and identity of interlayer cation. • Several in ACa{sub 2}Nb{sub 3}O{sub 10} series (A = Li, Na, K) exhibit high temperature polymorphism.

  4. A Thermally Insulating Textile Inspired by Polar Bear Hair.

    Science.gov (United States)

    Cui, Ying; Gong, Huaxin; Wang, Yujie; Li, Dewen; Bai, Hao

    2018-04-01

    Animals living in the extremely cold environment, such as polar bears, have shown amazing capability to keep warm, benefiting from their hollow hairs. Mimicking such a strategy in synthetic fibers would stimulate smart textiles for efficient personal thermal management, which plays an important role in preventing heat loss and improving efficiency in house warming energy consumption. Here, a "freeze-spinning" technique is used to realize continuous and large-scale fabrication of fibers with aligned porous structure, mimicking polar bear hairs, which is difficult to achieve by other methods. A textile woven with such biomimetic fibers shows an excellent thermal insulation property as well as good breathability and wearability. In addition to passively insulating heat loss, the textile can also function as a wearable heater, when doped with electroheating materials such as carbon nanotubes, to induce fast thermal response and uniform electroheating while maintaining its soft and porous nature for comfortable wearing. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Optimizing Neutron Thermal Scattering Effects in very High Temperature Reactors. Final Report

    International Nuclear Information System (INIS)

    Hawari, Ayman

    2014-01-01

    This project aims to develop a holistic understanding of the phenomenon of neutron thermalization in the VHTR. Neutron thermalization is dependent on the type and structure of the moderating material. The fact that the moderator (and reflector) in the VHTR is a solid material will introduce new and interesting considerations that do not apply in other (e.g. light water) reactors. The moderator structure is expected to undergo radiation induced changes as the irradiation (or burnup) history progresses. In this case, the induced changes in structure will have a direct impact on many properties including the neutronic behavior. This can be easily anticipated if one recognizes the dependence of neutron thermalization on the scattering law of the moderator. For the pebble bed reactor, it is anticipated that the moderating behavior can be tailored, e.g. using moderators that consist of composite materials, which could allow improved optimization of the moderator-to-fuel ratio.

  6. Nuclear Engineering Computer Modules, Thermal-Hydraulics, TH-3: High Temperature Gas Cooled Reactor Thermal-Hydraulics.

    Science.gov (United States)

    Reihman, Thomas C.

    This learning module is concerned with the temperature field, the heat transfer rates, and the coolant pressure drop in typical high temperature gas-cooled reactor (HTGR) fuel assemblies. As in all of the modules of this series, emphasis is placed on developing the theory and demonstrating its use with a simplified model. The heart of the module…

  7. AC Losses and Their Thermal Effect in High-Temperature Superconducting Machines

    DEFF Research Database (Denmark)

    Song, Xiaowei (Andy); Mijatovic, Nenad; Zou, Shengnan

    2016-01-01

    In transient operations or fault conditions, hightemperature superconducting (HTS) machines suffer ac losses, which have an influence on the thermal stability of superconducting windings. In this paper, a method to calculate ac losses and their thermal effect in HTS machines is presented....... The method consists of three submodels that are coupled only in one direction. The magnetic field distribution is first solved in a machine model, assuming a uniform current distribution in HTS windings. The magnetic fields on the boundaries are then used as inputs for an ac loss model that has a homogeneous...

  8. Plutonium and minor actinides management in thermal high - temperature reactors - the EU FP6 project puma

    International Nuclear Information System (INIS)

    Kuijper, J. C.

    2007-01-01

    The High Temperature gas-cooled Reactor (HTR) can fulfil a very useful niche for the purposes of Pu and Minor Actinide (MA) incineration due to its unique and unsurpassed safety features, as well as to the attractive incentives offered by the nature of the coated particle (CP) fuel. No European reactor of this type is currently available, but there has been, and still is, considerable interest internationally. Decisions to construct such a reactor in China and in South Africa have already been made or are about to be made. Apart from the unique and unsurpassed safety features offered by this reactor type, the nature of the CP fuel offers a number of attractive characteristics. In particular, it can withstand burn-ups far beyond that in either LWR or FR systems. Demonstrations as high as 75% FIMA have been achieved. The coated particle itself offers significantly improved proliferation resistance, and finally with a correct choice of the kernel composition, it can be a very effective support for direct geological disposal of the fuel. The overall objective of the PUMA project, a Specific Targeted Research Project (STREP) within the European Union 6th Framework (EU FP6), is to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO 2 -free energy generation. A number of important issues concerning the use of Pu and MA in gas-cooled reactors have already been dealt with in other projects, or are being treated in ongoing projects, e.g. as part of EU FP6. However, further steps are required to demonstrate the potential of HTRs as Pu/MA transmuters based on realistic/feasible designs of CP Pu/MA fuel and the PUMA focuses on necessary

  9. Effects of high-temperature thermal annealing on the electronic properties of In-Ga-Zn oxide thin films

    Energy Technology Data Exchange (ETDEWEB)

    Li, Qin; Song, Zhong Xiao; Ma, Fei, E-mail: mafei@mail.xjtu.edu.cn, E-mail: liyhemail@gmail.com; Li, Yan Huai, E-mail: mafei@mail.xjtu.edu.cn, E-mail: liyhemail@gmail.com [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an, Shaanxi 710049 (China); Xu, Ke Wei [State Key Laboratory for Mechanical Behavior of Materials, Xi' an Jiaotong University, Xi' an, Shaanxi 710049, China and Department of Physics and Opt-electronic Engineering, Xi' an University of Arts and Science, Xi' an, Shaanxi 710065 (China)

    2015-03-15

    Indium gallium zinc oxide (IGZO) thin films were deposited by radio-frequency magnetron sputtering at room-temperature. Then, thermal annealing was conducted to improve the structural ordering. X-ray diffraction and high-resolution transmission electron microscopy demonstrated that the as-deposited IGZO thin films were amorphous and crystallization occurred at 800 and 950 °C. As a result of crystallization at high temperature, the carrier concentration and the Hall mobility of IGZO thin films were sharply increased, which could be ascribed to the increased oxygen vacancies and improved structural ordering of the thin films.

  10. Radiative contribution to the thermal conductivity of fibrous insulations

    Science.gov (United States)

    Linford, R. M. F.; Schmitt, R. J.; Hughes, T. A.

    1974-01-01

    An approach is shown for using a simple two-flux model to interpret infrared transmission data for a variety of reuseable surface insulations materials and to calculate the radiation transmission. A description is given of preliminary experiments on mullite and silica-based materials. The calculated parameters are compared with the measured values of the total thermal conductivity, as determined on guarded hot plate equipment. It is pointed out that for many samples the newly developed four-flux model must be utilized because the scattering properties of the fibers are often dependent on the wavelength of the radiation.

  11. High Temperature Oxidation of Spark Plasma Sintered and Thermally Sprayed FeAl-Based Iron Aluminides

    Czech Academy of Sciences Publication Activity Database

    Haušild, P.; Karlík, M.; Skiba, T.; Sajdl, P.; Dubský, Jiří; Palm, M.

    2012-01-01

    Roč. 122, č. 3 (2012), s. 465-468 ISSN 0587-4246. [International Symposium on Physics of Materials (ISPMA)/12./. Prague, 04.09.2011-08.09.2011] Institutional support: RVO:61389021 Keywords : thermal spraying * plasma sintering Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.531, year: 2012

  12. Influence of coating on nanocrystalline magnetic properties during high temperature thermal ageing

    Energy Technology Data Exchange (ETDEWEB)

    Lekdim, Atef, E-mail: atef.lekdim@univ-lyon1.fr; Morel, Laurent; Raulet, Marie-Ange

    2017-05-15

    Since their birth or mergence the late 1980s, the nanocrystalline ultrasoft magnetic materials are taking a great importance in power electronic systems conception. One of the main advantages that make them more attractive nowadays is their ability to be packaged since the reduction of the magnetostrictive constant to almost zero. In aircraft applications, due to the high component compactness and to their location (for example near the jet engine), the operating temperature increases and may reach easily 200 °C and more. Consequently, the magnetic thermal ageing may occur but is, unfortunately, weakly studied. This paper focuses on the influence of the coating (packaging type) on the magnetic nanocrystalline performances during a thermal ageing. This study is based on monitoring the magnetic characteristics of two types of nanocrystalline cores (naked and coated) during a thermal activated ageing (100, 150 and 200 °C). Based on a dedicated monitoring protocol, a large magnetic characterization has been done and analyzed. Elsewhere, X-Ray Diffraction and magnetostriction measurements were carried out to support the study of the anisotropy energies evolution with ageing. This latter is discussed in this paper to explain and give hypothesis about the ageing phenomena. - Highlights: • The coating impacts drastically the magnetic properties during thermal ageing. • Irreversible ageing phenomena after the total coating breakage. • The deteriorations are related to the storage of the magnetoelastic anisotropy.

  13. New rapid-curing, stable polyimide polymers with high-temperature strength and thermal stability

    Science.gov (United States)

    Burns, E. A.; Jones, J. F.; Kendrick, W. R.; Lubowitz, H. R.; Thorpe, R. S.; Wilson, E. R.

    1969-01-01

    Additive-type polymerization reaction forms thermally stable polyimide polymers, thereby eliminating the volatile matter attendant with the condensation reaction. It is based on the utilization of reactive alicyclic rings positioned on the ends of polyimide prepolymers having relatively low molecular weights.

  14. Fusion blanket high-temperature heat transfer

    International Nuclear Information System (INIS)

    Fillo, J.A.

    1983-01-01

    Deep penetration of 14 MeV neutrons makes two-temperature region blankets feasible. A relatively low-temperature (approx. 300 0 C) metallic structure is the vacuum/coolant pressure boundary, while the interior of the blanket, which is a simple packed bed of nonstructural material, operates at very high temperatures (>1000 0 C). The water-cooled shell structure is thermally insulated from the steam-cooled interior. High-temperature steam can dramatically increase the efficiency of electric power generation, as well as produce hydrogen and oxygen-based synthetic fuels at high-efficiency

  15. Thermal sterilization of heat-sensitive products using high-temperature short-time sterilization.

    Science.gov (United States)

    Mann, A; Kiefer, M; Leuenberger, H

    2001-03-01

    High-temperature short-time (HTST) sterilization with a continuous-flow sterilizer, developed for this study, was evaluated. The evaluation was performed with respect to (a) the chemical degradation of two heat-sensitive drugs in HTST range (140-160 degrees C) and (b) the microbiological effect of HTST sterilization. Degradation kinetics of two heat-sensitive drugs showed that a high peak temperature sterilization process resulted in less chemical degradation for the same microbiological effect than a low peak temperature process. Both drugs investigated could be sterilized with acceptable degradation at HTST conditions. For the evaluation of the microbiological effect, Bacillus stearothermophilus ATCC 7953 spores were used as indicator bacteria. Indicator spore kinetics (D(T), z value, k, and E(a)), were determined in the HTST range. A comparison between the Bigelow model (z value concept) and the Arrhenius model, used to describe the temperature coefficient of the microbial inactivation, demonstrated that the Bigelow model is more accurate in prediction of D(T) values in the HTST range. The temperature coefficient decreased with increasing temperature. The influence of Ca(2+) ions and pH value on the heat resistance of the indicator spores, which is known under typical sterilization conditions, did not change under HTST conditions.

  16. Thermal Spray Coatings for High-Temperature Corrosion Protection in Biomass Co-Fired Boilers

    Science.gov (United States)

    Oksa, M.; Metsäjoki, J.; Kärki, J.

    2015-01-01

    There are over 1000 biomass boilers and about 500 plants using waste as fuel in Europe, and the numbers are increasing. Many of them encounter serious problems with high-temperature corrosion due to detrimental elements such as chlorides, alkali metals, and heavy metals. By HVOF spraying, it is possible to produce very dense and well-adhered coatings, which can be applied for corrosion protection of heat exchanger surfaces in biomass and waste-to-energy power plant boilers. Four HVOF coatings and one arc sprayed coating were exposed to actual biomass co-fired boiler conditions in superheater area with a probe measurement installation for 5900 h at 550 and 750 °C. The coating materials were Ni-Cr, IN625, Fe-Cr-W-Nb-Mo, and Ni-Cr-Ti. CJS and DJ Hybrid spray guns were used for HVOF spraying to compare the corrosion resistance of Ni-Cr coating structures. Reference materials were ferritic steel T92 and nickel super alloy A263. The circulating fluidized bed boiler burnt a mixture of wood, peat and coal. The coatings showed excellent corrosion resistance at 550 °C compared to the ferritic steel. At higher temperature, NiCr sprayed with CJS had the best corrosion resistance. IN625 was consumed almost completely during the exposure at 750 °C.

  17. Thermal conductivity of carbon felts, insulating materials with a high anisotropy; Conductivite thermique des feutres de carbone, isolants a forte anisotropie

    Energy Technology Data Exchange (ETDEWEB)

    Danes, F.E.; Bardon, J.P. [Centre National de la Recherche Scientifique, 44 - Nantes (France). Lab. de Thermocinetique

    1996-12-31

    Because of their high temperature resistance, carbon felts are used as thermal insulating materials for high temperature applications. The aim of this paper is to present a model that allows to calculate the thermal conductivity of felt fibers taking into account their high anisotropy and the contact resistance of fibers generated by the 3-D constriction phenomena which develop in fibers around each contact point. The study is divided in two parts: the first part concerns the bibliographic study of the different anisotropies of fibers and felts, while the second part presents the proposed conductivity model. (J.S.) 12 refs.

  18. Effects of carbon content on high-temperature mechanical and thermal fatigue properties of high-boron austenitic steels

    Directory of Open Access Journals (Sweden)

    Xiang Chen

    2016-01-01

    Full Text Available High-temperature mechanical properties of high-boron austenitic steels (HBASs were studied at 850 °C using a dynamic thermal-mechanical simulation testing machine. In addition, the thermal fatigue properties of the alloys were investigated using the self-restraint Uddeholm thermal fatigue test, during which the alloy specimens were cycled between room temperature and 800°C. Stereomicroscopy and scanning electron microscopy were used to study the surface cracks and cross-sectional microstructure of the alloy specimens after the thermal fatigue tests. The effects of carbon content on the mechanical properties at room temperature and high-temperature as well as thermal fatigue properties of the HBASs were also studied. The experimental results show that increasing carbon content induces changes in the microstructure and mechanical properties of the HBASs. The boride phase within the HBAS matrix exhibits a round and smooth morphology, and they are distributed in a discrete manner. The hardness of the alloys increases from 239 (0.19wt.% C to 302 (0.29wt.% C and 312 HV (0.37wt.% C; the tensile yield strength at 850 °C increases from 165.1 to 190.3 and 197.1 MPa; and the compressive yield strength increases from 166.1 to 167.9 and 184.4 MPa. The results of the thermal fatigue tests (performed for 300 cycles from room temperature to 800 °C indicate that the degree of thermal fatigue of the HBAS with 0.29wt.% C (rating of 2–3 is superior to those of the alloys with 0.19wt.% (rating of 4–5 and 0.37wt.% (rating of 3–4 carbon. The main cause of this difference is the ready precipitation of M23(C,B6-type borocarbides in the alloys with high carbon content during thermal fatigue testing. The precipitation and aggregation of borocarbide particles at the grain boundaries result in the deterioration of the thermal fatigue properties of the alloys.

  19. Mathematical model for creep and thermal shrinkage of concrete at high temperature

    International Nuclear Information System (INIS)

    Bazant, Z.P.

    1983-01-01

    Based on the existing limited test data, it is possible to set up an approximate constitutive model for creep and shrinkage at temperatures above 100 0 C, up to about 400 0 C. The model presented here describes the effect of various constant temperatures on the creep rate and the rate of aging, similar effects of the specific water content, the creep increase caused by simultaneous changes in moisture content, the thermal volume changes as well as the volume changes caused by changes in moisture content (drying shrinkage or thermal shrinkage), and the effect of pore pressure produced by heating. Generalizations to time-variable stresses and multiaxial stresses are also given. The model should allow more realistic analysis of reactor vessels and containments for accident situations, of concrete structures subjected to fire, of vessels for coal gasification or liquefaction, etc. (orig.)

  20. Thermal stress estimation in relation to spalling of HSC restrained with steel rings at high temperatures

    Directory of Open Access Journals (Sweden)

    Tanibe T.

    2013-09-01

    Full Text Available This paper reports on an experimental study regarding the behavior of steel ring-restrained concrete in response to fire exposure. The study was conducted to enable estimation of thermal stress based on steel ring strain in such concrete under the conditions of a RABT 30 heating curve. The specimens used were made from high-strength concrete (Fc: 80 MPa restrained using steel rings with thicknesses of 0.5, 8 and 18 mm.

  1. THR-TH: a high-temperature gas-cooled nuclear reactor core thermal hydraulics code

    Energy Technology Data Exchange (ETDEWEB)

    Vondy, D.R.

    1984-07-01

    The ORNL version of PEBBLE, the (RZ) pebble bed thermal hydraulics code, has been extended for application to a prismatic gas cooled reactor core. The supplemental treatment is of one-dimensional coolant flow in up to a three-dimensional core description. Power density data from a neutronics and exposure calculation are used as the basic information for the thermal hydraulics calculation of heat removal. Two-dimensional neutronics results may be expanded for a three-dimensional hydraulics calculation. The geometric description for the hydraulics problem is the same as used by the neutronics code. A two-dimensional thermal cell model is used to predict temperatures in the fuel channel. The capability is available in the local BOLD VENTURE computation system for reactor core analysis with capability to account for the effect of temperature feedback by nuclear cross section correlation. Some enhancements have also been added to the original code to add pebble bed modeling flexibility and to generate useful auxiliary results. For example, an estimate is made of the distribution of fuel temperatures based on average and extreme conditions regularly calculated at a number of locations.

  2. Thermal Cycling and High-Temperature Corrosion Tests of Rare Earth Silicate Environmental Barrier Coatings

    Science.gov (United States)

    Darthout, Émilien; Gitzhofer, François

    2017-12-01

    Lutetium and yttrium silicates, enriched with an additional secondary zirconia phase, environmental barrier coatings were synthesized by the solution precursor plasma spraying process on silicon carbide substrates. A custom-made oven was designed for thermal cycling and water vapor corrosion testing. The oven can test four specimens simultaneously and allows to evaluate environmental barrier performances under similar corrosion kinetics compared to turbine engines. Coatings structural evolution has been observed by SEM on the polished cross sections, and phase composition has been analyzed by XRD. All coatings have been thermally cycled between 1300 °C and the ambient temperature, without spallation, due to their porosity and the presence of additional secondary phase which increases the thermal cycling resistance. During water vapor exposure at 1200 °C, rare earth disilicates showed a good stability, which is contradictory with the literature, due to impurities—such as Si- and Al-hydroxides—in the water vapor jets. The presence of vertical cracks allowed the water vapor to reach the substrate and then to corrode it. It has been observed that thin vertical cracks induced some spallation after 24 h of corrosion.

  3. THR-TH: a high-temperature gas-cooled nuclear reactor core thermal hydraulics code

    International Nuclear Information System (INIS)

    Vondy, D.R.

    1984-07-01

    The ORNL version of PEBBLE, the (RZ) pebble bed thermal hydraulics code, has been extended for application to a prismatic gas cooled reactor core. The supplemental treatment is of one-dimensional coolant flow in up to a three-dimensional core description. Power density data from a neutronics and exposure calculation are used as the basic information for the thermal hydraulics calculation of heat removal. Two-dimensional neutronics results may be expanded for a three-dimensional hydraulics calculation. The geometric description for the hydraulics problem is the same as used by the neutronics code. A two-dimensional thermal cell model is used to predict temperatures in the fuel channel. The capability is available in the local BOLD VENTURE computation system for reactor core analysis with capability to account for the effect of temperature feedback by nuclear cross section correlation. Some enhancements have also been added to the original code to add pebble bed modeling flexibility and to generate useful auxiliary results. For example, an estimate is made of the distribution of fuel temperatures based on average and extreme conditions regularly calculated at a number of locations

  4. Thermal Performance of Cryogenic Multilayer Insulation at Various Layer Spacings

    Science.gov (United States)

    Johnson, Wesley Louis

    2010-01-01

    Multilayer insulation (MLI) has been shown to be the best performing cryogenic insulation system at high vacuum (less that 10 (exp 3) torr), and is widely used on spaceflight vehicles. Over the past 50 years, many investigations into MLI have yielded a general understanding of the many variables that are associated with MLI. MLI has been shown to be a function of variables such as warm boundary temperature, the number of reflector layers, and the spacer material in between reflectors, the interstitial gas pressure and the interstitial gas. Since the conduction between reflectors increases with the thickness of the spacer material, yet the radiation heat transfer is inversely proportional to the number of layers, it stands to reason that the thermal performance of MLI is a function of the number of layers per thickness, or layer density. Empirical equations that were derived based on some of the early tests showed that the conduction term was proportional to the layer density to a power. This power depended on the material combination and was determined by empirical test data. Many authors have graphically shown such optimal layer density, but none have provided any data at such low densities, or any method of determining this density. Keller, Cunnington, and Glassford showed MLI thermal performance as a function of layer density of high layer densities, but they didn't show a minimal layer density or any data below the supposed optimal layer density. However, it was recently discovered that by manipulating the derived empirical equations and taking a derivative with respect to layer density yields a solution for on optimal layer density. Various manufacturers have begun manufacturing MLI at densities below the optimal density. They began this based on the theory that increasing the distance between layers lowered the conductive heat transfer and they had no limitations on volume. By modifying the circumference of these blankets, the layer density can easily be

  5. The thermal expansion of a highly crystalline hexagonal BC2N compound synthesized under high temperature and pressure

    International Nuclear Information System (INIS)

    Wu Qinghua; Liu Zhongyuan; Hu Qianku; Li Hui; He Julong; Yu Dongli; Li Dongchun; Tian Yongjun

    2006-01-01

    The thermal expansion has been investigated for a highly crystalline hexagonal BC 2 N compound synthesized by the compression of a turbostratic B-C-N precursor with iron catalyst at the high temperature of 1500 deg. C and the high pressure of 5.5 GPa. The thermal expansion in the c direction is large and linear with an expansion coefficient of 35.86 x 10 -6 K -1 up to 1000 deg. C, while in the basal plane, the a dimension displays a slight linear contraction up to 750 deg. C with a contraction coefficient of -8.76 x 10 -7 K -1 , but above 750 deg. C a linear expansion is observed with a larger expansion coefficient of 1.52 x 10 -6 K -1

  6. Thermal insulation. Non-utilized energy need not be generated. Four rules for a successful thermal insulation by means of building insulation; Waermedaemmung. Energie, die nicht gebraucht wird, muss man nicht erzeugen. Vier Regeln fuer erfolgreichen Waermeschutz durch Gebaeudedaemmung

    Energy Technology Data Exchange (ETDEWEB)

    Patschke, Markus [3E-Consult, Nordkirchen (Germany); Drewer, Arnold [IpeG-Institut, Paderborn (Germany)

    2011-07-15

    The heat supply of buildings causes nearly one third of the energy consumption of an industrialized country. In 2006, the climate-adjusted heat consumption of private households in Germany amounted nearly 600 billion kWh. This consumption caused more than 167 million tons of CO{sub 2}. Heat insulation measures in buildings are required for all heat-transferring enveloping surface. Under this aspect, the contribution under consideration reports on four fundamental rules for a cost-efficient building insulation: (a) Only heated rooms should be insulated thermally; (b) Location and thermal insulation of cavities; (c) Selection of a suitable insulating material; (d) Consideration of an economic sustainability.

  7. High performance thermal insulation systems (HiPTI). Vacuum insulated products (VIP). Proceedings of the international conference and workshop

    Energy Technology Data Exchange (ETDEWEB)

    Zimmermann, M.; Bertschinger, H.

    2001-07-01

    These are the proceedings of the International Conference and Workshop held at EMPA Duebendorf, Switzerland, in January 2001. The papers presented at the conference's first day included contributions on the role of high-performance insulation in energy efficiency - providing an overview of available technologies and reviewing physical aspects of heat transfer and the development of thermal insulation as well as the state of the art of glazing technologies such as high-performance and vacuum glazing. Also, vacuum-insulated products (VIP) with fumed silica, applications of VIP systems in technical building systems, nanogels, VIP packaging materials and technologies, measurement of physical properties, VIP for advanced retrofit solutions for buildings and existing and future applications for advanced low energy building are discussed. Finally, research and development concerning VIP for buildings are reported on. The workshops held on the second day covered a preliminary study on high-performance thermal insulation materials with gastight porosity, flexible pipes with high performance thermal insulation, evaluation of modern insulation systems by simulation methods as well as the development of vacuum insulation panels with a stainless steel envelope.

  8. Effect of the hydro-thermal load history on the high-temperature creep of HTR-concrete

    International Nuclear Information System (INIS)

    Diederichs, U.; Rostasy, F.S.; Becker, G.

    1991-01-01

    In the research and development works for the prestressed concrete vessel for the HTR-500 high temperature reactor, the comprehensive tests concerning mix design, manufacture as well as mechanical and thermal behavior of the concrete have been carried out. The concrete was put to the numerous tests for determining the strength and the creep behavior at elevated temperature. In the real PCRV, the concrete is heated at different heating rate depending on the location of a certain volume element of the concrete in the structure. Furthermore, the heat transport simultaneously causes the moisture transport. For this reason, the test has been planned to investigate the transient creep at various heating rates and in different states of moisture during heating to the accident temperature up to 300 deg C. The cylindrical specimens were used for the high temperature creep test. The test procedure and the test results are reported. It was shown that the thermal history (heating rate, duration of holding at a certain temperature and so on) determines the transient creep deformation to a great extent. (K.I.)

  9. High temperature thermal conductivity measurements of UO/sub 2/ by Direct Electrical Heating. Final report. [MANTRA-III

    Energy Technology Data Exchange (ETDEWEB)

    Bassett, B

    1980-10-01

    High temperature properties of reactor type UO/sub 2/ pellets were measured using a Direct Electrical Heating (DEH) Facility. Modifications to the experimental apparatus have been made so that successful and reproducible DEH runs may be carried out while protecting the pellets from oxidation at high temperature. X-ray diffraction measurements on the UO/sub 2/ pellets have been made before and after runs to assure that sample oxidation has not occurred. A computer code has been developed that will model the experiment using equations that describe physical properties of the material. This code allows these equations to be checked by comparing the model results to collected data. The thermal conductivity equation for UO/sub 2/ proposed by Weilbacher has been used for this analysis. By adjusting the empirical parameters in Weilbacher's equation, experimental data can be matched by the code. From the several runs analyzed, the resulting thermal conductivity equation is lambda = 1/4.79 + 0.0247T/ + 1.06 x 10/sup -3/ exp(-1.62/kT/) - 4410. exp(-3.71/kT/) where lambda is in w/cm K, k is the Boltzman constant, and T is the temperature in Kelvin.

  10. Study of surfaces and surface layers on high temperature materials after short-time thermal loads

    International Nuclear Information System (INIS)

    Bolt, H.; Hoven, H.; Koizlik, K.; Linke, J.; Nickel, H.; Wallura, E.

    1985-11-01

    Being part of the plasma-wall interaction during TOKAMAK operation, erosion- and redeposition processes of First Wall materials substantially influence plasma parameters as well as the properties of the First Wall. An important redeposition process of eroded material is the formation of thin films by atomic condensation. Examinations of First Wall components after TOKAMAK operation lead to the assumption that these thin metallic films tend to agglomerate to small particles under subsequent heat load. In laboratory experiments it is shown that thin metallic films on various substrates can agglomerate under short time high heat fluxes and also under longer lasting lower thermal loads, thus verifying the ''agglomeration hypothesis''. (orig.) [de

  11. Thermo-Mechanical and Thermal behavior of High-Temperature Structural Materials.

    Science.gov (United States)

    1982-12-31

    EPR spectrum at 80K of an "as-grown" MgO:Ni crystal with the magnetic field ranging from 0 to 500 Gauss oriented along the > axis. The single...3000 4000 5000 GAUSS -Fig. 2. EPR spectrum of Ni-doped MgO crystal (a) before and (b) after being reduced for 2 hours. T-B0 :L!{)gt 1o 161 A MgO 14 0...Band 24, 5 P01g., Nov. 1935 , pp. 636-664. 13. BrennanJ. J., Bentsen, L. D., and Hasselman, D.P.H., "Measurement of the Thermal Conductivity and

  12. High-flux/high-temperature solar thermal conversion: technology development and advanced applications

    OpenAIRE

    Romero Manuel; González-Aguilar José

    2016-01-01

    Solar Thermal Power Plants have generated in the last 10 years a dynamic market for renewable energy industry and a pro-active networking within R&D community worldwide. By end 2015, there are about 5 GW installed in the world, most of them still concentrated in only two countries, Spain and the US, though a rapid process of globalization is taking place in the last few years and now ambitious market deployment is starting in countries like South Africa, Chile, Saudi Arabia, India, United Ara...

  13. Investigation of the thermal expansion of the refractory materials at high temperatures

    Science.gov (United States)

    Kostanovskiy, A.; Kostanovskaya, M.; Zeodinov, M.; Pronkin, A.

    2017-11-01

    We present the experimental investigation of the relative elongation and the coefficient of linear thermal expansion for monocrystaline alumina Al2O3 (1200 K - 1860 K), zirconia ZrO2 (1200 K - 2730 K) and siliconized silicon carbide SiC+Si (1150 K - 2500 K) in the specified range of temperatures. The following approach is used to measure the relative elongation: the through-cylindrical-marks located in the centre of isothermal part of the sample, and the measurement of temperature by two blackbody models, taken out of the area of the sample where the relative elongation is measured.

  14. Thermal curing of PBI membranes for high temperature PEM fuel cells

    DEFF Research Database (Denmark)

    Aili, David; Cleemann, Lars N.; Li, Qingfeng

    2012-01-01

    (MEAs) is currently hampering the commercial viability of the technology. In the present study, thermoset PBI membranes were prepared by curing the membranes under inert atmosphere at temperatures of up to 350 °C prior to the acid doping. The systematic membrane characterizations with respect...... to solubility, phosphoric acid doping, radical-oxidative resistance and mechanical strength indicated that the PBI membranes were irreversibly cured by the thermal treatment. After curing, the PBI membranes demonstrated features that are fundamental characteristics of a thermoset resin including complete...

  15. Thermal Processing Effects on the Adhesive Strength of PS304 High Temperature Solid Lubricant Coatings

    Science.gov (United States)

    DellaCorte, Christopher; Edmonds, Brian J.; Benoy, Patricia A.

    2001-01-01

    In this paper the effects of post deposition heat treatments on the cohesive and adhesive strength properties of PS304, a plasma sprayed nickel-chrome based, high temperature solid lubricant coating deposited on stainless steel, are studied. Plasma spray deposited coating samples were exposed in air at temperatures from 432 to 650 C for up to 500 hr to promote residual stress relief, enhance particle to particle bonding and increase coating to substrate bond strength. Coating pull-off strength was measured using a commercial adhesion tester that utilizes 13 mm diameter aluminum pull studs attached to the coating surface with epoxy. Pull off force was automatically recorded and converted to coating pull off strength. As deposited coating samples were also tested as a baseline. The as-deposited (untreated) samples either delaminated at the coating-substrate interface or failed internally (cohesive failure) at about 17 MPa. Samples heat treated at temperatures above 540 C for 100 hr or at 600 C or above for more than 24 hr exhibited strengths above 31 MPa, nearly a two fold increase. Coating failure occurred inside the body of the coating (cohesive failure) for nearly all of the heat-treated samples and only occasionally at the coating substrate interface (adhesive failure). Metallographic analyses of heat-treated coatings indicate that the Nickel-Chromium binder in the PS304 appears to have segregated into two phases, a high nickel matrix phase and a high chromium precipitated phase. Analysis of the precipitates indicates the presence of silicon, a constituent of a flow enhancing additive in the commercial NiCr powder. The exact nature and structure of the precipitate phase is not known. This microstructural change is believed to be partially responsible for the coating strength increase. Diffusion bonding between particles may also be playing a role. Increasing the heat treatment temperature, exposure time or both accelerate the heat treatment process. Preliminary

  16. Thermal expansion and decomposition of jarosite: a high-temperature neutron diffraction study

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwu [Los Alamos National Laboratory; Zhao, Yusheng [Los Alamos National Laboratory; Vogel, Sven C [Los Alamos National Laboratory; Hickmott, Donald D [Los Alamos National Laboratory; Daemen, Luke L [Los Alamos National Laboratory; Hartl, Monika A [Los Alamos National Laboratory

    2009-01-01

    The structure of deuterated jarosite, KFe{sub 3}(SO{sub 4}){sub 2}(OD){sub 6}, was investigated using time-of-flight neutron diffraction up to its dehydroxylation temperature. Rietveld analysis reveals that with increasing temperature, its c dimension expands at a rate {approx}10 times greater than that for a. This anisotropy of thermal expansion is due to rapid increase in the thickness of the (001) sheet of [Fe(O,OH){sub 6}] octahedra and [SO{sub 4}] tetrahedra with increasing temperature. Fitting of the measured cell volumes yields a coefficient of thermal expansion, a = a{sub 0} + a{sub 1} T, where a{sub 0} = 1.01 x 10{sup -4} K{sup -1} and a{sub 1} = -1.15 x 10{sup -7} K{sup -2}. On heating, the hydrogen bonds, O1{hor_ellipsis}D-O3, through which the (001) octahedral-tetrahedral sheets are held together, become weakened, as reflected by an increase in the D{hor_ellipsis}O1 distance and a concomitant decrease in the O3-D distance with increasing temperature. On further heating to 575 K, jarosite starts to decompose into nanocrystalline yavapaiite and hematite (as well as water vapor), a direct result of the breaking of the hydrogen bonds that hold the jarosite structure together.

  17. WESF cesium capsule behavior at high temperature or during thermal cycling

    International Nuclear Information System (INIS)

    Tingey, G.L.; Gray, W.J.; Shippell, R.J.; Katayama, Y.B.

    1985-06-01

    Double-walled stainless steel (SS) capsules prepared for storage of radioactive 137 Cs from defense waste are now being considered for use as sources for commercial irradiation. Cesium was recovered at B-plant from the high-level radioactive waste generated during processing of defense nuclear fuel. It was then purified, converted to the chloride form, and encapsulated at the Hanford Waste Encapsulation and Storage Facility (WESF). The molten cesium chloride salt was encapsulated by pouring it into the inner of two concentric SS cylinders. Each cylinder was fitted with a SS end cap that was welded in place by inert gas-tungsten arc welding. The capsule configuration and dimensions are shown in Figure 1. In a recent review of the safety of these capsules, Tingey, Wheelwright, and Lytle (1984) indicated that experimental studies were continuing to produce long-term corrosion data, to reaffirm capsule integrity during a 90-min fire where capsule temperatures reached 800 0 C, to monitor mechanical properties as a function of time, and to assess the effects of thermal cycling due to periodic transfer of the capsules from a water storage pool to the air environment of an irradiator facility. This report covers results from tests that simulated the effects of the 90-min fire and from thermal cycling actual WESF cesium capsules for 3845 cycles over a period of six months. 11 refs., 39 figs., 9 tabs

  18. Modelling of thermal removal of tars in a high temperature stage fed by a plasma torch

    International Nuclear Information System (INIS)

    Fourcault, A.; Marias, F.; Michon, U.

    2010-01-01

    The thermal degradation of tars in a chamber fed by a non-transferred plasma torch is theoretically examined in this study. The input of this reactor is a product gas coming from a gasification unit with a temperature of about 800 o C. According to literature, naphthalene and toluene are chosen as model compounds to represent the behaviour of their classes. According to this choice and to the data available in the literature, a reaction pathway for the thermal degradation of tars and its associated kinetics are proposed in this study. This mechanism is introduced in a CSTR model in order to check the influence of the operating parameters of the reactor on the degradation efficiency. These computations clearly show that a complete conversion of toluene (>99.9%) and an important conversion of naphthalene (96.7%) can be reached in the reactor, with concentration levels compatible with the further use of gas engines for electricity production. This theoretical study requires to be validated by comparison with experimental results.

  19. Modelling of thermal removal of tars in a high temperature stage fed by a plasma torch

    Energy Technology Data Exchange (ETDEWEB)

    Fourcault, A. [Laboratoire Thermique Energetique et Procedes, LaTEP-ENSGTI, rue Jules Ferry, BP 7511, 64075 Pau Cedex (France); Europlasma, 21 rue Daugere, 33520 Bruges (France); Marias, F. [Laboratoire Thermique Energetique et Procedes, LaTEP-ENSGTI, rue Jules Ferry, BP 7511, 64075 Pau Cedex (France); Michon, U. [Europlasma, 21 rue Daugere, 33520 Bruges (France)

    2010-09-15

    The thermal degradation of tars in a chamber fed by a non-transferred plasma torch is theoretically examined in this study. The input of this reactor is a product gas coming from a gasification unit with a temperature of about 800 C. According to literature, naphthalene and toluene are chosen as model compounds to represent the behaviour of their classes. According to this choice and to the data available in the literature, a reaction pathway for the thermal degradation of tars and its associated kinetics are proposed in this study. This mechanism is introduced in a CSTR model in order to check the influence of the operating parameters of the reactor on the degradation efficiency. These computations clearly show that a complete conversion of toluene (>99.9%) and an important conversion of naphthalene (96.7%) can be reached in the reactor, with concentration levels compatible with the further use of gas engines for electricity production. This theoretical study requires to be validated by comparison with experimental results. (author)

  20. Thermal shock behaviour of H and H/He-exposed tungsten at high temperature

    International Nuclear Information System (INIS)

    Lemahieu, N; Linke, J; Pintsuk, G; Wirtz, M; Greuner, H; Maier, H; Oost, G Van; Noterdaeme, J-M

    2016-01-01

    Polycrystalline tungsten samples were characterized and exposed to a pure H beam or mixed H/He beam containing 6% He in GLADIS at a surface temperature of 600 °C, 1000 °C, or 1500 °C. After 5400 s of exposure time with a heat flux of 10.5 MW m −2 , the total accumulated fluence of 2 × 10 25 m −2 was reached. Thereafter, edge localized mode (ELM)-like thermal shocks with a duration of 1 ms and an absorbed power density of 190 MW m −2 and 380 MW m −2 were applied on the samples in JUDITH 1. During the thermal shocks, the base temperature was kept at 1000 °C. The ELM-experiments with the lowest transient power density did not result in any detected damage. The other tests showed the beginning of crack formation for every sample, except the sample pre-exposed with the pure H-beam at 1500 °C in GLADIS. This sample was roughened, but did not show any crack initiation. With exception to the roughened sample, the category of ELM-induced damage for the pre-exposed samples is identical to the reference tests without pre-exposure to a particle flux. (paper)

  1. Carbon dioxide as working fluid for medium and high-temperature concentrated solar thermal systems

    Directory of Open Access Journals (Sweden)

    Van Duong

    2014-03-01

    Full Text Available This paper explores the benefits and drawbacks of using carbon dioxide in solar thermal systems at medium and high operating temperatures. For medium temperatures, application of CO2 in non-imaging-optics based compound parabolic concentrators (CPC combined with evacuated-tube collectors is studied. These collectors have been shown to obtain efficiencies higher than 40% operating at around 200℃ without the need of tracking. Validated numerical models of external compound parabolic concentrators (XCPCs are used to simulate their performance using CO2 as working fluid. For higher temperatures, a mathematical model is implemented to analyze the operating performance of a parabolic trough solar collector (PTC using CO2 at temperatures between 100℃ and 600℃.

  2. Video and thermal imaging system for monitoring interiors of high temperature reaction vessels

    Science.gov (United States)

    Saveliev, Alexei V [Chicago, IL; Zelepouga, Serguei A [Hoffman Estates, IL; Rue, David M [Chicago, IL

    2012-01-10

    A system and method for real-time monitoring of the interior of a combustor or gasifier wherein light emitted by the interior surface of a refractory wall of the combustor or gasifier is collected using an imaging fiber optic bundle having a light receiving end and a light output end. Color information in the light is captured with primary color (RGB) filters or complimentary color (GMCY) filters placed over individual pixels of color sensors disposed within a digital color camera in a BAYER mosaic layout, producing RGB signal outputs or GMCY signal outputs. The signal outputs are processed using intensity ratios of the primary color filters or the complimentary color filters, producing video images and/or thermal images of the interior of the combustor or gasifier.

  3. Synthesis, ionic conductivity, and thermal properties of proton conducting polymer electrolyte for high temperature fuel cell

    Energy Technology Data Exchange (ETDEWEB)

    Itoh, Takahito; Hamaguchi, Yohei; Uno, Takahiro; Kubo, Masataka [Department of Chemistry for Materials, Faculty of Engineering, Mie University, 1577 Kurima Machiya-cho, Tsu, Mie 514-8507 (Japan); Aihara, Yuichi; Sonai, Atsuo [Samsung Yokohama Research Institute, 2-7 Sugasawa-cho, Tsurumi-ku, Yokohama 230-0027 (Japan)

    2006-01-16

    Hyperbranched polymer (poly-1a) with sulfonic acid groups at the end of chains was successfully synthesized. Interpenetration reaction of poly-1a with a hyperbranched polymer with acryloyl groups at the end of chains (poly-1b) as a cross-linker afforded a tough electrolyte membrane. The poly-1a and the resulting electrolyte membrane showed the ionic conductivities of 7x10{sup -4} and 8x10{sup -5} S/cm, respectively, at 150C under dry condition. The ionic conductivities of the poly-1a and the electrolyte membrane exhibited the VTF type temperature dependence. And also, both poly-1a and the resulting electrolyte membrane were thermally stable up to 200C. (author)

  4. High temperature superconductor cable concepts for fusion magnets

    CERN Document Server

    AUTHOR|(CDS)2078397

    2013-01-01

    Three concepts of high temperature superconductor cables carrying kA currents (RACC, CORC and TSTC) are investigated, optimized and evaluated in the scope of their applicability as conductor in fusion magnets. The magnetic field and temperature dependence of the cables is measured; the thermal expansion and conductivity of structure, insulation and filling materials are investigated. High temperature superconductor winding packs for fusion magnets are calculated and compared with corresponding low temperature superconductor cases.

  5. Study of magneto-thermal coupled phenomena in High Temperature Superconductors

    International Nuclear Information System (INIS)

    Berger, Kevin

    2006-01-01

    Theoretical study of HTS devices requires to solve magneto-thermal coupled equations. As coupling effects are very important in these materials, the development of numerical tools is almost unavoidable. A computer code based on the Finite Difference Method was developed in this direction, making it possible to solve 1D and 2D problems. It is then possible to numerically simulate the behavior of HTS. Study of the losses in a Bi-2223 current lead, fed by an alternating current at 50 Hz, subjected to a DC magnetic field and immersed in a liquid nitrogen bath, is then carried out in a theoretical and experimental way. Thermal instabilities were observed experimentally. This phenomenon was studied starting from the search for the stable and unstable steady state solutions. For a given current and magnetic field, a maximum temperature above which recovery of the superconducting state is not possible could be defined. YBCO pellets can trap strong magnetic fields and be used as very powerful cryo-magnets. The dynamic response of these pellets, subjected to variations of a magnetic field, is studied in a detailed way (current density, magnetic field and temperature distributions). Results of the simulations show significant differences when the influences of the magnetic field and temperature are taken into account in the electrical law E(J). An optimum of the maximum magnetic field to apply leading to a maximum of trapped flux could be given. This information is of great interest as it enables the design of the most effective pulse magnetization device. (author) [fr

  6. Characterization of Ternary NiTiPd High-Temperature Shape-Memory Alloys under Load-Biased Thermal Cycling

    Science.gov (United States)

    Bigelow, Glen S.; Padula, Santo A.; Noebe, Ronald D.; Garg, Anita; Gaydosh, Darrell

    2010-01-01

    While NiTiPd alloys have been extensively studied for proposed use in high-temperature shape-memory applications, little is known about the shape-memory response of these materials under stress. Consequently, the isobaric thermal cyclic responses of five (Ni,Pd)49.5Ti50.5 alloys with constant stoichiometry and Pd contents ranging from 15 to 46 at. pct were investigated. From these tests, transformation temperatures, transformation strain (which is proportional to work output), and unrecovered strain per cycle (a measure of dimensional instability) were determined as a function of stress for each alloy. It was found that increasing the Pd content over this range resulted in a linear increase in transformation temperature, as expected. At a given stress level, work output decreased while the amount of unrecovered strain produced during each load-biased thermal cycle increased with increasing Pd content, during the initial thermal cycles. However, continued thermal cycling at constant stress resulted in a saturation of the work output and nearly eliminated further unrecovered strain under certain conditions, resulting in stable behavior amenable to many actuator applications.

  7. Thermal-performance study of liquid metal fast breeder reactor insulation

    International Nuclear Information System (INIS)

    Shiu, K.K.

    1980-09-01

    Three types of metallic thermal insulation were investigated analytically and experimentally: multilayer reflective plates, multilayer honeycomb composite, and multilayer screens. Each type was subjected to evacuated and nonevacuated conditions, where thermal measurements were made to determine thermal-physical characteristics. A variation of the separation distance between adjacent reflective plates of multilayer reflective plates and multilayer screen insulation was also experimentally studied to reveal its significance. One configuration of the multilayer screen insulation was further selected to be examined in sodium and sodium oxide environments. The emissivity of Type 304 stainless steel used in comprising the insulation was measured by employing infrared technology. A comprehensive model was developed to describe the different proposed types of thermal insulation. Various modes of heat transfer inherent in each type of insulation were addressed and their relative importance compared. Provision was also made in the model to allow accurate simulation of possible sodium and sodium oxide contamination of the insulation. The thermal-radiation contribution to heat transfer in the temperature range of interest for LMFBR's was found to be moderate, and the suppression of natural convection within the insulation was vital in preserving its insulating properties. Experimental data were compared with the model and other published results. Moreover, the three proposed test samples were assessed and compared under various conditions as viable LMFBR thermal insulations

  8. Thermally Stable and Electrically Conductive, Vertically Aligned Carbon Nanotube/Silicon Infiltrated Composite Structures for High-Temperature Electrodes.

    Science.gov (United States)

    Zou, Qi Ming; Deng, Lei Min; Li, Da Wei; Zhou, Yun Shen; Golgir, Hossein Rabiee; Keramatnejad, Kamran; Fan, Li Sha; Jiang, Lan; Silvain, Jean-Francois; Lu, Yong Feng

    2017-10-25

    Traditional ceramic-based, high-temperature electrode materials (e.g., lanthanum chromate) are severely limited due to their conditional electrical conductivity and poor stability under harsh circumstances. Advanced composite structures based on vertically aligned carbon nanotubes (VACNTs) and high-temperature ceramics are expected to address this grand challenge, in which ceramic serves as a shielding layer protecting the VACNTs from the oxidation and erosive environment, while the VACNTs work as a conductor. However, it is still a great challenge to fabricate VACNT/ceramic composite structures due to the limited diffusion of ceramics inside the VACNT arrays. In this work, we report on the controllable fabrication of infiltrated (and noninfiltrated) VACNT/silicon composite structures via thermal chemical vapor deposition (CVD) [and laser-assisted CVD]. In laser-assisted CVD, low-crystalline silicon (Si) was quickly deposited at the VACNT subsurfaces/surfaces followed by the formation of high-crystalline Si layers, thus resulting in noninfiltrated composite structures. Unlike laser-assisted CVD, thermal CVD activated the precursors inside and outside the VACNTs simultaneously, which realized uniform infiltrated VACNT/Si composite structures. The growth mechanisms for infiltrated and noninfiltrated VACNT/ceramic composites, which we attributed to the different temperature distributions and gas diffusion mechanism in VACNTs, were investigated. More importantly, the as-farbicated composite structures exhibited excellent multifunctional properties, such as excellent antioxidative ability (up to 1100 °C), high thermal stability (up to 1400 °C), good high velocity hot gas erosion resistance, and good electrical conductivity (∼8.95 Sm -1 at 823 K). The work presented here brings a simple, new approach to the fabrication of advanced composite structures for hot electrode applications.

  9. Determination of heat conductivity and thermal diffusivity of waste glass melter feed: Extension to high temperatures

    International Nuclear Information System (INIS)

    Rice, Jarrett A.; Pokorny, Richard; Schweiger, Michael J.; Hrma, Pavel R.

    2014-01-01

    The heat conductivity (λ) and the thermal diffusivity (a) of reacting glass batch, or melter feed, control the heat flux into and within the cold cap, a layer of reacting material floating on the pool of molten glass in an all-electric continuous waste glass melter. After previously estimating λ of melter feed at temperatures up to 680 deg C, we focus in this work on the λ(T) function at T > 680 deg C, at which the feed material becomes foamy. We used a customized experimental setup consisting of a large cylindrical crucible with an assembly of thermocouples, which monitored the evolution of the temperature field while the crucible with feed was heated at a constant rate from room temperature up to 1100°C. Approximating measured temperature profiles by polynomial functions, we used the heat transfer equation to estimate the λ(T) approximation function, which we subsequently optimized using the finite-volume method combined with least-squares analysis. The heat conductivity increased as the temperature increased until the feed began to expand into foam, at which point the conductivity dropped. It began to increase again as the foam turned into a bubble-free glass melt. We discuss the implications of this behavior for the mathematical modeling of the cold cap

  10. Thermal performance of an open thermosyphon using nanofluid for evacuated tubular high temperature air solar collector

    International Nuclear Information System (INIS)

    Liu, Zhen-Hua; Hu, Ren-Lin; Lu, Lin; Zhao, Feng; Xiao, Hong-shen

    2013-01-01

    Highlights: • A novel solar air collector with simplified CPC and open thermosyphon is designed and tested. • Simplified CPC has a much lower cost at the expense of slight efficiency loss. • Nanofluid effectively improves thermal performance of the above solar air collector. • Solar air collector with open thermosyphon is better than that with concentric tube. - Abstract: A novel evacuated tubular solar air collector integrated with simplified CPC (compound parabolic concentrator) and special open thermosyphon using water based CuO nanofluid as the working fluid is designed to provide air with high and moderate temperature. The experimental system has two linked panels and each panel includes an evacuated tube, a simplified CPC and an open thermosyphon. Outdoor experimental study has been carried out to investigate the actual solar collecting performance of the designed system. Experimental results show that air outlet temperature and system collecting efficiency of the solar air collector using nanofluid as the open thermosyphon’s working fluid are both higher than that using water. Its maximum air outlet temperature exceeds 170 °C at the air volume rate of 7.6 m 3 /h in winter, even though the experimental system consists of only two collecting panels. The solar collecting performance of the solar collector integrated with open thermosyphon is also compared with that integrated with common concentric tube. Experimental results show that the solar collector integrated with open thermosyphon has a much better collecting performance

  11. Thermal fluid dynamics study of nuclear advanced reactors of high temperature using RELAP5-3D

    International Nuclear Information System (INIS)

    Scari, Maria Elizabeth

    2017-01-01

    Fourth Generation nuclear reactors (GEN-IV) are being designed with special features such as intrinsic safety, reduction of isotopic inventory and use of fuel in proliferation-resistant cycles. Therefore, the investigation and evaluation of operational and safety aspects of the GEN-IV reactors have been the subject of numerous studies by the international community and also in Brazil. In 2008, in Brazil, was created the National Institute of Science and Technology of Innovative Nuclear Reactors, focusing on studies of projects and systems of new generation reactors, which included GEN-IV reactors as well as advanced PWR (Pressurized Water Reactor) concepts. The Department of Nuclear Engineering of the Federal University of Minas Gerais (DEN-UFMG) is a partner of this Institute, having started studies on the GEN-IV reactors in the year 2007. Therefore, in order to add knowledge to these studies, in this work, three projects of advanced reactors were considered to verify the simulation capability of the thermo-hydraulic RELAP5-3D code for these systems, either in stationary operation or in transient situations. The addition of new working fluids such as ammonia, carbon dioxide, helium, hydrogen, various types of liquid salts, among them Flibe, lead, lithium-bismuth, lithium-lead, was a major breakthrough in this version of the code, allowing also the simulation of GEN-IV reactors. The modeling of the respective core of an HTTR (High Temperature Engineering Test Reactor), HTR-10 (High Temperature Test Module Reactor) and LS-VHTR (Liquid-Salt-Cooled Very-High-Temperature Reactor) were developed and verified in steady state comparing the values found through the calculations with reference data from other simulations, when it is possible. The first two reactors use helium gas as coolant and the LS-VHTR uses a mixture of 66% LiF and 34% of BeF 2 , the LiF-BeF 2 , also know as Flibe. All the studied reactors use enriched uranium as fuel, in form of TRISO (Tristructural

  12. Standard Practice for Evaluating Thermal Insulation Materials for Use in Solar Collectors

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1994-01-01

    1.1 This practice sets forth a testing methodology for evaluating the properties of thermal insulation materials to be used in solar collectors with concentration ratios of less than 10. Tests are given herein to evaluate the pH, surface burning characteristics, moisture adsorption, water absorption, thermal resistance, linear shrinkage (or expansion), hot surface performance, and accelerated aging. This practice provides a test for surface burning characteristics but does not provide a methodology for determining combustibility performance of thermal insulation materials. 1.2 The tests shall apply to blanket, rigid board, loose-fill, and foam thermal insulation materials used in solar collectors. Other thermal insulation materials shall be tested in accordance with the provisions set forth herein and should not be excluded from consideration. 1.3 The assumption is made that elevated temperature, moisture, and applied stresses are the primary factors contributing to the degradation of thermal insulation mat...

  13. Rigid Polyurethane Foam Thermal Insulation Protected with Mineral Intumescent Mat

    Directory of Open Access Journals (Sweden)

    Kirpluks Mikelis

    2014-12-01

    Full Text Available One of the biggest disadvantages of rigid polyurethane (PU foams is its low thermal resistance, high flammability and high smoke production. Greatest advantage of this thermal insulation material is its low thermal conductivity (λ, which at 18-28 mW/(m•K is superior to other materials. To lower the flammability of PU foams, different flame retardants (FR are used. Usually, industrially viable are halogenated liquid FRs but recent trends in EU regulations show that they are not desirable any more. Main concern is toxicity of smoke and health hazard form volatiles in PU foam materials. Development of intumescent passive fire protection for foam materials would answer problems with flammability without using halogenated FRs. It is possible to add expandable graphite (EG into PU foam structure but this increases the thermal conductivity greatly. Thus, the main advantage of PU foam is lost. To decrease the flammability of PU foams, three different contents 3%; 9% and 15% of EG were added to PU foam formulation. Sample with 15% of EG increased λ of PU foam from 24.0 to 30.0 mW/(m•K. This paper describes the study where PU foam developed from renewable resources is protected with thermally expandable intumescent mat from Technical Fibre Products Ltd. (TFP as an alternative to EG added into PU material. TFP produces range of mineral fibre mats with EG that produce passive fire barrier. Two type mats were used to develop sandwich-type PU foams. Also, synergy effect of non-halogenated FR, dimethyl propyl phosphate and EG was studied. Flammability of developed materials was assessed using Cone Calorimeter equipment. Density, thermal conductivity, compression strength and modulus of elasticity were tested for developed PU foams. PU foam morphology was assessed from scanning electron microscopy images.

  14. Saving millions by thermal insulation; Miljoenen besparen door goede isolatie

    Energy Technology Data Exchange (ETDEWEB)

    Van der Velden, U. [Nederlands Centrum voor Technische Isolatie NCTI, spijkenisse (Netherlands)

    2009-07-15

    Corrosion under insulation (CUI) can be reduced by the application of a correctly designed, installed and maintained insulation system. In refrigeration plants a heat flow will occur from the warm outside towards the cold inside. Hot air, containing more moisture, will be distributed to the cold components of the installation, such as separators, intermediate coolers, piping and valves, thus not only facilitating CUI, but also seriously compromising the thermal performance of the system. Furthermore, this moisture could condensate or freeze and compromise the integrity of the installation. Insulation in cold systems is built up with closed cell materials, such as elastomeric foam, PIR (polyisocyanurate) or cellular glass. On the outside a vapor barrier (e.g. reinforced aluminium foil) is essential to prevent hot moist air from penetrating the system. For protection against weather influences and/or mechanical damage, the system should be finished with a (non)metal cladding. [Dutch] Corrosie onder isolatie (CUI) kan worden beperkt door toepassing van een correct ontworpen, geinstalleerd en onderhouden isolatiesysteem. Bij koude-isolatiesystemen treedt een warmtestroom van buiten naar binnen op. Warme lucht - die meer vocht bevat - dringt naar installatiecomponenten, zoals afscheiders, tussenkoelers, leidingen en afstuiters, waarbij niet alleen het risico op CUI aanzienlijk toeneemt, maar ook de isolatiewaarde van het systeem gereduceerd wordt. Vocht kan hierbij ook nog condenseren of bevriezen en de integriteit van de hele installatie in gevaar brengen. Koude-isolatiesystemen dienen te worden opgebouwd met gesloten cel-materiaal, zoals elastomeer schuim, PIR (polyisocyanurate) of cellulair glas. Het systeem dient aan de buitenzijde te worden voorzien van een dampremmende laag (van bijvoorbeeld versterkt aluminiumfolie) om binnendringend vocht te blokkeren. In buitencondities moet het systeem worden voorzien van een (metalen of niet-metalen) eindafwerking, die

  15. A Network Model for the Effective Thermal Conductivity of Rigid Fibrous Refractory Insulations

    Science.gov (United States)

    Marschall, Jochen; Cooper, D. M. (Technical Monitor)

    1995-01-01

    A procedure is described for computing the effective thermal conductivity of a rigid fibrous refractory insulation. The insulation is modeled as a 3-dimensional Cartesian network of thermal conductance. The values and volume distributions of the conductance are assigned to reflect the physical properties of the insulation, its constituent fibers, and any permeating gas. The effective thermal conductivity is computed by considering the simultaneous energy transport by solid conduction, gas conduction and radiation through a cubic volume of model insulation; thus the coupling between heat transfer modes is retained (within the simplifications inherent to the model), rather than suppressed by treating these heat transfer modes as independent. The model takes into account insulation composition, density and fiber anisotropy, as well as the geometric and material properties of the constituent fibers. A relatively good agreement, between calculated and experimentally derived thermal conductivity values, is obtained for a variety of rigid fibrous insulations.

  16. Development of THYDE-HTGR: computer code for transient thermal-hydraulics of high-temperature gas-cooled reactor

    International Nuclear Information System (INIS)

    Hirano, Masashi; Hada, Kazuhiko

    1990-04-01

    The THYDE-HTGR code has been developed for transient thermal-hydraulic analyses of high-temperature gas-cooled reactors, based on the THYDE-W code. THYDE-W is a code developed at JAERI for the simulation of Light Water Reactor plant dynamics during various types of transients including loss-of-coolant accidents. THYDE-HTGR solves the conservation equations of mass, momentum and energy for compressible gas, or single-phase or two-phase flow. The major code modification from THYDE-W is to treat helium loops as well as water loops. In parallel to this, modification has been made for the neutron kinetics to be applicable to helium-cooled graphite-moderated reactors, for the heat transfer models to be applicable to various types of heat exchangers, and so forth. In order to assess the validity of the modifications, analyses of some of the experiments conducted at the High Temperature Test Loop of ERANS have been performed. In this report, the models applied in THYDE-HTGR are described focusing on the present modifications and the results from the assessment calculations are presented. (author)

  17. Peculiar Features of Thermal Aging and Degradation of Rapidly Quenched Stainless Steels under High-Temperature Exposures

    Science.gov (United States)

    Shulga, A. V.

    2017-12-01

    This article presents the results of comparative studies of mechanical properties and microstructure of nuclear fuel tubes and semifinished stainless steel items fabricated by consolidation of rapidly quenched powders and by conventional technology after high-temperature exposures at 600 and 700°C. Tensile tests of nuclear fuel tube ring specimens of stainless austenitic steel of grade AISI 316 and ferritic-martensitic steel are performed at room temperature. The microstructure and distribution of carbon and boron are analyzed by metallography and autoradiography in nuclear fuel tubes and semifinished items. Rapidly quenched powders of the considered steels are obtained by the plasma rotating electrode process. Positive influence of consolidation of rapidly quenched powders on mechanical properties after high-temperature aging is confirmed. The correlation between homogeneous distribution of carbon and boron and mechanical properties of the considered steel is determined. The effects of thermal aging and degradation of the considered steels are determined at 600°C and 700°C, respectively.

  18. Verification of High Temperature Free Atom Thermal Scattering in MERCURY Compared to TART

    International Nuclear Information System (INIS)

    Cullen, D E; McKinley, S; Hagmann, C

    2006-01-01

    This is part of a series of reports verifying the accuracy of the relatively new MERCURY [1] Monte Carlo particle transport code by comparing its results to those of the older TART [2] Monte Carlo particle transport code. In the future we hope to extend these comparisons to include deterministic (Sn) codes [3]. Here we verify the accuracy of the free atom thermal scattering model [4] by using it over a very large temperature range. We would like to be able to use these Monte Carlo codes for astrophysical applications, where the temperature of the medium can be extremely high compared to the temperatures we normally encounter in our terrestrial applications [5]. The temperature is so high that is it often defined in eV rather than Kelvin. For a correspondence between the two scale 293.6 Kelvin (room temperature) corresponds to 0.0253 eV ∼ 1/40 eV. So that 1 eV temperature is about 12,000 Kelvin, and 1 keV temperature is about 12 million Kelvin. Here we use a relatively small system measured in cm, but by using ρR scaling [6] our results are equally applicable to systems measured in Km or thousands of Km or any size that we need for astrophysical applications. The emphasis here is not on modeling any given real system, but rather in verifying the accuracy of the free atom model to represent theoretical results over a large temperature range. There are two primary objectives of this report: (1) Verify agreement between MERCURY and TART results, both using continuous energy cross sections. In particular we want to verify the free atom scattering treatment in MERCURY as used over an extended temperature range; by comparison to many other codes for TART this has already been verified over many years [4, 7]. (2) Demonstrate that this agreement depends on using continuous energy cross sections. To demonstrate this we also present TART using the Multi-Band method [8, 9], which accounts for resonance self-shielding, and Multi-Group method, without self-shielding [9

  19. Thermal properties of KUO3(s) and K2U2O7 - by high temperature Calvet calorimeter

    International Nuclear Information System (INIS)

    Jayanthi, K.; Iyer, V.S.; Venugopal, V.

    1998-01-01

    The thermal properties of KUO 3 (s) and K 2 U 2 O 7 (s) were determined using a high temperature Calvet calorimeter by drop method. The enthalpy increments, (H T o - H 298.15 0 ), in kJ/mol for KUO 3 (s) and K 2 U 2 O 7 (s) can be represented by, H T o - H 298.15 0 KUO 3 (s) kJ/mol ± 0.7 = -39.15 + 0.129T + 0.1005x10 -4 T 2 (369-714K) and H T o -H 298.15 0 K 2 U 2 O 7 (s) kJ/mol ± 0.7 = -52.99 + 0.1361T + 0.146x10 -3 T 2 (391 - 683K). (author)

  20. Enterococcus faecium as a Salmonella surrogate in the thermal processing of wheat flour: Influence of water activity at high temperatures.

    Science.gov (United States)

    Liu, Shuxiang; Rojas, Rossana V; Gray, Peter; Zhu, Mei-Jun; Tang, Juming

    2018-09-01

    This study investigated the influence of temperature-dependent water activity (a w ) on thermal resistances of Enterococcus faecium NRRL B-2354 (E. faecium) and Salmonella Enteritidis PT 30 (S. Enteritidis) in wheat flour. The a w for wheat flour samples at 20, 40, and 60 °C was determined by a vapor sorption analyzer and at 75, 80 and 85 °C using custom-built thermal cells with high temperature humidity sensors. Full-factorial isothermal inactivation studies of both strains in sealed aluminum-test-cells included three temperatures (75, 80, and 85 °C) and three a w,25°C levels (0.30, 0.45 and 0.60 within ±0.02 range, prior to the thermal treatments). Isotherm results of wheat flour demonstrate a significant increase (P processing of wheat flour for control of Salmonella over a moisture content of 10-14% and treatment temperatures between 75 and 85 °C. Copyright © 2018 Elsevier Ltd. All rights reserved.

  1. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    International Nuclear Information System (INIS)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-01-01

    A rapid thermal anneal (RTA) in an NH 3 ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 0 C in NH 3 and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (≥1000 0 C) RTA in Ar completely converted W into the low resistivity (31 μΩ cm) tetragonal WSi 2 phase. In contrast, after a prior 900 0 C RTA in NH 3 , N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi 2 formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 0 C NH 3 anneal. The NH 3 -treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 0 C, at which point some increase in contact resistance was measured

  2. High-temperature stability of chemically vapor-deposited tungsten-silicon couples rapid thermal annealed in ammonia and argon

    Energy Technology Data Exchange (ETDEWEB)

    Broadbent, E.K.; Morgan, A.E.; Flanner, J.M.; Coulman, B.; Sadana, D.K.; Burrow, B.J.; Ellwanger, R.C.

    1988-12-15

    A rapid thermal anneal (RTA) in an NH/sub 3/ ambient has been found to increase the thermal stability of W films chemically vapor deposited (CVD) on Si. W films deposited onto single-crystal Si by low-pressure CVD were rapid thermal annealed at temperatures between 500 and 1100 /sup 0/C in NH/sub 3/ and Ar ambients. The reactions were studied using Rutherford backscattering spectrometry, x-ray diffraction, Auger electron spectroscopy, transmission electron microscopy, and four-point resistivity probe. High-temperature (greater than or equal to1000 /sup 0/C) RTA in Ar completely converted W into the low resistivity (31 ..mu cap omega.. cm) tetragonal WSi/sub 2/ phase. In contrast, after a prior 900 /sup 0/C RTA in NH/sub 3/, N inclusion within the W film and at the W/Si interface almost completely suppressed the W-Si reaction. Detailed examination, however, revealed some patches of WSi/sub 2/ formed at the interface accompanied by long tunnels extending into the substrate, and some crystalline precipitates in the substrate close to the interface. The associated interfacial contact resistance was only slightly altered by the 900 /sup 0/C NH/sub 3/ anneal. The NH/sub 3/-treated W film acted as a diffusion barrier in an Al/W/Si contact metallurgy up to at least 550 /sup 0/C, at which point some increase in contact resistance was measured.

  3. A thermal insulation system intended for a prestressed concrete vessel

    International Nuclear Information System (INIS)

    Aubert, Gilles; Petit, Guy.

    1975-01-01

    The description is given of a thermal insulation system withstanding the pressure of a vaporisable fluid for a prestressed concrete vessel, particularly the vessel of a boiling water nuclear reactor. The ring in the lower part of the vessel has, between the fluid inlet pipes and the bottom of the vessel, an annular opening of which the bottom edge is integral with an annular part rising inside the ring and parallel to it. This ring is hermetically connected to the bottom of the vessel and is coated with a metal lagging, at least facing the annular opening. This annular opening is made in the ring half-way up between the fluid inlet pipes and the bottom of the vessel. It is connected to the bottom of the vessel through the internal structure enveloping the reactor core [fr

  4. A mathematical and numerical framework for the analysis of compressible thermal convection in gases at very high temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Lappa, Marcello, E-mail: marcello.lappa@strath.ac.uk

    2016-05-15

    The relevance of non-equilibrium phenomena, nonlinear behavior, gravitational effects and fluid compressibility in a wide range of problems related to high-temperature gas-dynamics, especially in thermal, mechanical and nuclear engineering, calls for a concerted approach using the tools of the kinetic theory of gases, statistical physics, quantum mechanics, thermodynamics and mathematical modeling in synergy with advanced numerical strategies for the solution of the Navier–Stokes equations. The reason behind such a need is that in many instances of relevance in this field one witnesses a departure from canonical models and the resulting inadequacy of standard CFD approaches, especially those traditionally used to deal with thermal (buoyancy) convection problems. Starting from microscopic considerations and typical concepts of molecular dynamics, passing through the Boltzmann equation and its known solutions, we show how it is possible to remove past assumptions and elaborate an algorithm capable of targeting the broadest range of applications. Moving beyond the Boussinesq approximation, the Sutherland law and the principle of energy equipartition, the resulting method allows most of the fluid properties (density, viscosity, thermal conductivity, heat capacity and diffusivity, etc.) to be derived in a rational and natural way while keeping empirical contamination to the minimum. Special attention is deserved as well to the well-known pressure issue. With the application of the socalled multiple pressure variables concept and a projection-like numerical approach, difficulties with such a term in the momentum equation are circumvented by allowing the hydrodynamic pressure to decouple from its thermodynamic counterpart. The final result is a flexible and modular framework that on the one hand is able to account for all the molecule (translational, rotational and vibrational) degrees of freedom and their effective excitation, and on the other hand can guarantee

  5. High temperature pipeline design

    Energy Technology Data Exchange (ETDEWEB)

    Greenslade, J.G. [Colt Engineering, Calgary, AB (Canada). Pipelines Dept.; Nixon, J.F. [Nixon Geotech Ltd., Calgary, AB (Canada); Dyck, D.W. [Stress Tech Engineering Inc., Calgary, AB (Canada)

    2004-07-01

    It is impractical to transport bitumen and heavy oil by pipelines at ambient temperature unless diluents are added to reduce the viscosity. A diluted bitumen pipeline is commonly referred to as a dilbit pipeline. The diluent routinely used is natural gas condensate. Since natural gas condensate is limited in supply, it must be recovered and reused at high cost. This paper presented an alternative to the use of diluent to reduce the viscosity of heavy oil or bitumen. The following two basic design issues for a hot bitumen (hotbit) pipeline were presented: (1) modelling the restart problem, and, (2) establishing the maximum practical operating temperature. The transient behaviour during restart of a high temperature pipeline carrying viscous fluids was modelled using the concept of flow capacity. Although the design conditions were hypothetical, they could be encountered in the Athabasca oilsands. It was shown that environmental disturbances occur when the fluid is cooled during shut down because the ground temperature near the pipeline rises. This can change growing conditions, even near deeply buried insulated pipelines. Axial thermal loads also constrain the design and operation of a buried pipeline as higher operating temperatures are considered. As such, strain based design provides the opportunity to design for higher operating temperature than allowable stress based design methods. Expansion loops can partially relieve the thermal stress at a given temperature. As the design temperature increase, there is a point at which above grade pipelines become attractive options, although the materials and welding procedures must be suitable for low temperature service. 3 refs., 1 tab., 10 figs.

  6. Thermal Insulation System for Non-Vacuum Applications Including a Multilayer Composite

    Science.gov (United States)

    Fesmire, James E. (Inventor)

    2017-01-01

    The thermal insulation system of the present invention is for non-vacuum applications and is specifically tailored to the ambient pressure environment with any level of humidity or moisture. The thermal insulation system includes a multilayered composite including i) at least one thermal insulation layer and at least one compressible barrier layer provided as alternating, successive layers, and ii) at least one reflective film provided on at least one surface of the thermal insulation layer and/or said compressible barrier layer. The different layers and materials and their combinations are designed to provide low effective thermal conductivity for the system by managing all modes of heat transfer. The thermal insulation system includes an optional outer casing surrounding the multilayered composite. The thermal insulation system is particularly suited for use in any sub-ambient temperature environment where moisture or its adverse effects are a concern. The thermal insulation system provides physical resilience against damaging mechanical effects including compression, flexure, impact, vibration, and thermal expansion/contraction.

  7. Influence of light masonry mortar on the thermal insulation of a solid brick wall

    Energy Technology Data Exchange (ETDEWEB)

    Kupke, C

    1980-12-01

    For calculations of the thermal insulation of structural components according to DIN 4108 and to the Thermal Insulation Ordinance, characteristic data of thermal conductivity are used which are contained in DIN 4108 and in the Bundesanzeiger in Supplements to the publication of material characteristics for the calculation of thermal insulation according to the Thermal Insulation Ordinance. For masonry, this value is equivalent to the thermal conductivity of the bricks, including mortar joints. The mortar considered is standard mortar, group II, according to DIN 1053. In the last few years, in order to improve the thermal insulation, mortars of low thermal conductivity and low volume weight - so-called light masonry mortars - have been used to an increasing extent. The improvement in thermal conductivity as compared with standard mortar is referred to as ..delta..lambda; it depends mostly on the thermal conductivity of the light mortar and the bricks. In the article, the laws governing the influence of light masonry mortar on the thermal insulation of masonry of solid bricks and solid blocks are reviewed.

  8. Property comparisons of commercially available silica-based microporous insulations I. Machinability and thermal dimensional stability

    International Nuclear Information System (INIS)

    Kramer, Daniel P.; McNeil, Dennis C.; Ruhkamp, Joseph D.; Wells, Donna J.; Stringer, Robert L.; Howell, Edwin I.

    2002-01-01

    Maximizing the thermal to electrical conversion efficiency of a nuclear space power system requires that all of the available thermal energy be utilized in the most efficient manner. Microporous insulations are attractive for application in space power systems due to their very low thermal conductivity. Over the last few years, several new silica-based microporous insulating materials have become commercially available. Property comparisons of the various insulations obtained from company literature and experiments on microporous sample specimens are discussed. The results demonstrate that their machinability and thermal dimensional stability as a function of time at temperature and atmosphere are dependent on the particular material

  9. Thermal properties of a sandwich construction insulated with Polyurethane (DC-System)

    DEFF Research Database (Denmark)

    Jensen, Rasmus Lund; Dreau, Jerome Le

    Rigid polyurethane foam (PUR) is a good thermal insulation product for buildings, mainly due to its low thermal conductivity (λ ≈ 20 mW/m.K), low permeability to water and stability over time. The other types of insulation products available on the market have a significantly higher thermal...... conductivity: + 50% for expanded polystyrene (λ ≈ 30 mW/m.K), + 75% for mineral wools (λ ≈ 35 mW/m.K), etc. Despite its low thermal conductivity, polyurethane foam (PUR) is not much used as insulation material for walls because of its low resistance to fire. The most common PUR boards are classified C-s2-d0...

  10. Reduced thermal budget processing of Y--Ba--Cu--O high temperature superconducting thin films by metalorganic chemical vapor deposition

    International Nuclear Information System (INIS)

    Singh, R.; Sinha, S.; Hsu, N.J.; Ng, J.T.C.; Chou, P.; Thakur, R.P.S.; Narayan, J.

    1991-01-01

    Metalorganic chemical vapor deposition (MOCVD) has the potential of emerging as a viable technique to fabricate ribbons, tapes, coated wires, and the deposition of films of high temperature superconductors, and related materials. As a reduced thermal budget processing technique, rapid isothermal processing (RIP) based on incoherent radiation as the source of energy can be usefully coupled to conventional MOCVD. In this paper we report on the deposition and characterization of high quality superconducting thin films of Y--Ba--Cu--O (YBCO) on MgO and SrTiO 3 substrates by RIP assisted MOCVD. By using a mixture of N 2 O and O 2 as the oxygen source films deposited initially at 600 degree C for 1 min and then at 740 degree C for 30 min are primarily c-axis oriented and with zero resistance being observed at 84 and 89 K for MgO and SrTiO 3 substrates, respectively. The zero magnetic field current densities at 77 K for MgO and SrTiO 3 substrates are 1.2x10 6 and 1.5x10 6 A/cm 2 , respectively. It is envisaged that high energy photons from the incoherent light source and the use of a mixture of N 2 O and O 2 as the oxygen source, assist chemical reactions and lower overall thermal budget for processing of these films

  11. Thermal Degradation Kinetics Modeling of Benzophenones and Xanthones during High-Temperature Oxidation of Cyclopia genistoides (L.) Vent. Plant Material.

    Science.gov (United States)

    Beelders, Theresa; de Beer, Dalene; Joubert, Elizabeth

    2015-06-10

    Degradation of the major benzophenones, iriflophenone-3-C-glucoside-4-O-glucoside and iriflophenone-3-C-glucoside, and the major xanthones, mangiferin and isomangiferin, of Cyclopia genistoides followed first-order reaction kinetics during high-temperature oxidation of the plant material at 80 and 90 °C. Iriflophenone-3-C-glucoside-4-O-glucoside was shown to be the most thermally stable compound. Isomangiferin was the second most stable compound at 80 °C, while its degradation rate constant was influenced the most by increased temperature. Mangiferin and iriflophenone-3-C-glucoside had comparable degradation rate constants at 80 °C. The thermal degradation kinetic model was subsequently evaluated by subjecting different batches of plant material to oxidative conditions (90 °C/16 h). The model accurately predicted the individual contents of three of the compounds in aqueous extracts prepared from oxidized plant material. The impact of benzophenone and xanthone degradation was reflected in the decreased total antioxidant capacity of the aqueous extracts, as determined using the oxygen radical absorbance capacity and DPPH(•) scavenging assays.

  12. Bio-based polyurethane foams toward applications beyond thermal insulation

    International Nuclear Information System (INIS)

    Gama, Nuno V.; Soares, Belinda; Freire, Carmen S.R.; Silva, Rui; Neto, Carlos P.; Barros-Timmons, Ana; Ferreira, Artur

    2015-01-01

    Highlights: • Coffee grounds wastes were successfully liquefied yielding a bio-based polyol. • Coffee grounds derived foams formulations were optimized by tuning reagents’ contents. • The viscoelastic properties of these foams are promising to expand their applications. - Abstract: In this work the preparation of viscoelastic bio-based polyurethane foams (PUFs) using polyols obtained via acid liquefaction of coffee grounds wastes has been optimized. In a first stage, the effect of different ratios of isocyanate content to hydroxyl number (0.6, 0.7 and 0.8) and of three distinct percentages of catalyst (3%, 5% and 7%) on the extent of the polymerization reaction was studied by infrared spectroscopy. Next, different percentages of surfactant (14%, 16% and 18%) and blowing agent (12%, 14% and 16%) were used to assess their effect on the density, thermal conductivity and mechanical properties of the foams, including their recovery time. The mechanical properties of the ensuing foams proved to be very interesting due to their viscoelastic behavior. PUFs were also characterized by scanning electron microscopy (SEM) revealing a typical cellular structure and by thermogravimetric analysis (TGA) which proved that these materials are thermally stable up to 190 °C. These results suggest other potential applications for these materials beyond heat insulation in areas where damping properties can be an added value

  13. High-temperature acquifer thermal storage and underground heat storage; IEA ECES Annex 12: Hochtemperatur-Erdwaermesonden- und Aquiferwaermespeicher

    Energy Technology Data Exchange (ETDEWEB)

    Sanner, B.; Knoblich, K. [Giessen Univ. (Germany). Inst. fuer Angewandte Geowissenschaften; Koch, M.; Adinolfi, M. [Stuttgart Univ. (Germany). Inst. fuer Siedlungswasserbau, Wasserguete und Abfallwirtschaft

    1998-12-31

    Heat storage is essential for the reconciliation of heat supply and demand. The earth has already proved to be an excellent medium for storing large amounts of heat over longer periods of time, for instance during the cold and hot season. The efficiency of the storage is the better the lower storage losses are at high temperature levels. Unfortunately this can not be easily achieved. While thermal underground stores, which are widely used for cold storage, have proved to perform quite well at temperatures between 10 C - 40 C, it has been rather difficult to achieve similar results at higher temperatures up to 150 C as test and demonstration plants of the 1980s proved. This issue has again attracted so much interest that the IEA launched a project on high temperature underground storage in December 1998. (orig.) [Deutsch] Waermespeicherung ist von entscheidender Bedeutung, wenn es darum geht, ein Waermeangebot mit einer Waermenachfrage zeitlich zur Deckung zu bringen. Der Untergrund hat sich schon seit vielen Jahren als ein geeignetes Medium erwiesen, groessere Waermepumpen ueber laengere Zeitraeume wie etwa die kalten und warmen Jahreszeiten zu speichern. Die Effizienz eines solchen Speichers steigt mit der Hoehe des erreichten Temperaturniveaus und mit sinkenden Speicherverlusten, was leider eher gegenlaeufige Erscheinungen sind. Waehrend thermische Untergrundspeicher im Temperaturbereich von 10-40 C inzwischen erfolgreich demonstriert wurden und vor allem zur Kaeltespeicherung auch bereits vielfach eingesetzt werden, haben hoehere Temperaturen bis etwa 150 C in den Versuchs- und Demonstrationsanlagen der 80er Jahre vielfaeltige Probleme bereitet. Im Gefolge eines erneuten Interesses an unterirdischer thermischer Energiespeicherung wurde im Dezember 1997 ein Vorhaben des IEA Energiespeicherprogramms zu Untergrund-Waermespeichern hoeherer Temperatur eingerichtet. (orig.)

  14. High-temperature stable absorber coatings for linear concentrating solar thermal power plants; Hochtemperaturstabile Absorberschichten fuer linear konzentrierende solarthermische Kraftwerke

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, Christina

    2009-03-23

    This work describes the development of new absorber coatings for different applications - para-bolic trough and linear Fresnel collectors - and operating conditions - absorber in vacuum or in air. The demand for higher efficiencies of solar thermal power plants using parabolic trough technology results in higher temperatures in the collectors and on the absorber tubes. As heat losses increase strongly with increasing temperatures, the need for a lower emissivity of the absorber coating at constant absorptivity arises. The linear Fresnel application envisions ab-sorber tubes stable in air at high temperatures of about 450 C, which are to date commercially not available. This work comprises the theoretical background, the modeling and the fabrication of absorber tubes including the technology transfer to a production-size inline sputter coater. In annealing tests and accompanying optical measurements, degradation processes have been observed and specified more precisely by material characterization techniques. The simulations provided the capability of different materials used as potential IR-reflector. The highest selectivity can be achieved by applying silver which consequently has been chosen for the application in absorber coatings of the parabolic trough technology. Thin silver films how-ever need to be stabilized when used at high temperatures. Appropriate barrier layers as well as process and layer parameters were identified. A high selectivity was achieved and stability of the absorber coating for 1200 h at 500 C in vacuum has been demonstrated. For the application in air, silver was also analyzed as a potential IR-reflector. Even though the stability could be increased considerably, it nevertheless proved to be insufficient. The main factors influencing stability in a positive way are the use of higher quality polishing, additional barrier layers and adequate process parameters. This knowledge was applied for developing coatings which are stable in air at

  15. Geological exploration for a high-temperature aquifer thermal energy storage (HT-ATES) system: a case study from Oman

    Science.gov (United States)

    Winterleitner, Gerd; Schütz, Felina; Huenges, Ernst

    2017-04-01

    , as second potential storage horizon, were deposited in a carbonate ramp setting. Individual facies belts extend over kilometres and thus horizontal reservoir connectivity is expected to be good with minor facies variability. Thin-section analyses point to the fossil-rich sections with high porosities and permeabilities and thus good storage qualities. Fluid flow and thermal modelling indicate that both potential storage horizons show good to very good storage characteristics but also have challenges such as reservoir heterogeneity and connectivity. In particular the tilting of the thermocline, specific to high-temperature systems poses a major challenge. We investigated scenarios to counterbalance the distortion of the subsurface heat-plume, which includes adjustments of the salinity contrast between injected and aquifer fluid to prohibit buoyancy-driven flow. Additionally, geological structures ("HT-ATES traps" e.g.: fault structures) were modelled in detail in order to analyse their suitability as high-temperature storage system. First results show that an effective HT-ATES trap is necessary in the alluvial fan system in order to keep in control of the heat-plume. Salinity adjustments are sufficient in the carbonate-dominated sequences where vertical permeability contrasts are higher and constitute natural vertical flow barriers.

  16. Techno-economic study of hydrogen production by high temperature electrolysis and coupling with different thermal energy sources

    International Nuclear Information System (INIS)

    Rivera-Tinoco, R.

    2009-03-01

    This work focuses on the techno-economic study of massive hydrogen production by the High Temperature Electrolysis (HTE) process and also deals with the possibility of producing the steam needed in the process by using different thermal energy sources. Among several sources, those retained in this study are the biomass and domestic waste incineration units, as well as two nuclear reactors (European Pressurised water Reactor - EPR and Sodium Fast Reactor - SFR). Firstly, the technical evaluation of the steam production by each of these sources was carried out. Then, the design and modelling of the equipments composing the process, specially the electrolysers (Solid Oxides Electrolysis Cells), are presented. Finally, the hydrogen production cost for each energy sources coupled with the HTE process is calculated. Moreover, several sensibility studies were performed in order to determine the process key parameter and to evaluate the influence of the unit size effect, the electric energy cost, maintenance, the cells current density, their investment cost and their lifespan on the hydrogen production cost. Our results show that the thermal energy cost is much more influent on the hydrogen production cost than the steam temperature at the outlet stream of the thermal source. It seems also that the key parameters for this process are the electric energy cost and the c ells lifespan. The first one contributes for more than 70% of the hydrogen production cost. From several cell lifespan values, it seems that a 3 year value, rather than 1 year, could lead to a hydrogen production cost reduced on 34%. However, longer lifespan values going from 5 to 10 years would only lead to a 8% reduction on the hydrogen production cost. (author)

  17. KNO3/NaNO3 - Graphite materials for thermal energy storage at high temperature: Part I. - Elaboration methods and thermal properties

    International Nuclear Information System (INIS)

    Acem, Zoubir; Lopez, Jerome; Palomo Del Barrio, Elena

    2010-01-01

    Composites graphite/salt for thermal energy storage at high temperature (∼200 deg. C) have been developed and tested. As at low temperature in the past, graphite has been used to enhance the thermal conductivity of the eutectic system KNO 3 /NaNO 3 . A new elaboration method has been proposed as an alternative to graphite foams infiltration. It consists of cold-compression of a physical mixing of expanded natural graphite particles and salt powder. Two different compression routes have been investigated: uni-axial compression and isostatic compression. The first part of the paper has been devoted to the analysis of the thermal properties of these new graphite/salt composites. It is proven that cold-compression is a simple and efficient technique for improving the salt thermal conductivity. For instance, graphite amounts between 15 and 20%wt lead to apparent thermal conductivities close to 20 W/m/K (20 times greater than the thermal conductivity of the salt). Furthermore, some advantages in terms of cost and safety are expected because materials elaboration is carried out at room temperature. The second part of the paper is focused on the analyses of the phase transition properties of these graphite/salt composites materials.

  18. New composites graphite/salt for high temperature thermal energy storage: From elaboration to development of thermal characterization methods for orthotropic conductive materials

    International Nuclear Information System (INIS)

    Acem, Zoubir

    2007-01-01

    This PhD is carried out within the framework of DISTOR (European) and HTPSTOCK (French) projects, which have for objective to conceive and study new graphite/salt composites dedicated to high temperature energy storage (>200 deg. C). She is split into two distinct part. The first one focused mainly on works linked with elaboration and thermal characterisation of these new composites. The different composites ways of elaboration (Dispersion, uniaxial compression, isostatic) associated to the different kind of graphite (Natural expanded graphite (ENG), synthetic graphite) investigated during the PhD are presented. The results of the thermal characterization campaign of these composites are also presented and permit to highlight the impact of graphite in the thermal behaviour of studied materials. Based on these results, modelling studies of the evolution of the thermal conductivity have been undertaken to deepen the understanding of the effect of graphite (quantity, size of particles) on the effective conductivity composites. The second one describes the thermal characterization devices and associated thermo-kinetics models which had to be developed and adapted to the specificities of newly developed materials. This concerns mainly the materials prepared by compression, which present orthotropic properties and are difficult to reproduce. So, the characterization of this kind of material is very difficult and tedious. That is why we are committed to develop and adapt existing methods of characterization to allow the complete thermal characterisation of an orthotropic conductive material from a single experimentation on a single sample. (author) [fr

  19. Negative thermal expansion up to 1000 C of ZrTiO4-Al2TiO5 ceramics for high-temperature applications

    International Nuclear Information System (INIS)

    Kim, I.J.; Kim, H.C.; Han, I.S.; Aneziris, C.G.

    2005-01-01

    High temperature structural ceramics based on Al 2 TiO 5 -ZrTiO 4 (ZAT) having excellent thermal-shock-resistance were synthesized by a reaction sintering. The ZAT ceramics sintered at 1600 C had a negative thermal expansions up to 1000 C and a much lower thermal expansion coefficient (0.3 ∝ 1.3 x 10 -6 /K) than that of polycrystalline Al 2 TiO 5 (1.5 x 10 -6 /K). These low thermal expansion are apparently due to a combination of microcracking caused by the large thermal expansion anisotropy of the crystal axes of the Al 2 TiO 5 phase. The microstructural degradation of the composites after various thermal treatment for high temperature applications were analyzed by scanning electron microscopy, X-ray diffraction, ultrasonic and dilatometer. (orig.)

  20. Optimization of thermal insulation to achieve energy savings in low energy house (refurbishment)

    International Nuclear Information System (INIS)

    Bojić, Milorad; Miletić, Marko; Bojić, Ljubiša

    2014-01-01

    Highlights: • For buildings that require heating, a thickness of their thermal insulation is optimized. • The objective was to improve energy efficiency of the building. • The optimization is performed by using EnergyPlus and Hooke–Jeeves method. • The embodied energy of thermal insulation and the entire life cycle of the house are taken into account. - Abstract: Due to the current environmental situation, saving energy and reducing CO 2 emission have become the leading drive in modern research. For buildings that require heating, one of the solutions is to optimize a thickness of their thermal insulation and thus improve energy efficiency and reduce energy needs. In this paper, for a small residential house in Serbia, an optimization in the thickness of its thermal insulation layer is investigated by using EnergyPlus software and Hooke–Jeeves direct search method. The embodied energy of thermal insulation is taken into account. The optimization is done for the entire life cycle of thermal insulation. The results show the optimal thickness of thermal insulation that yields the minimum primary energy consumption

  1. Lighter touch keeps in the heat. [Advantages of low-thermal-mass insulation

    Energy Technology Data Exchange (ETDEWEB)

    Pipes, A.

    1979-04-01

    Low-thermal-mass insulation of ceramic fibers and light refractory materials is more suitable to applications with intermittent processes and lower-temperature melting and retreating, where the heat-retention requirements do not require traditional furnace design. Old furnaces can be retrofitted by replacing bricks with insulation or by veneering. Insulating materials include ceramic, alumina, and quartz fibers, and microtherm in the form of blocks, blankets and other shapes. 4 figures. (DCK)

  2. Neutronics and Thermal Hydraulics Analysis of a Conceptual Ultra-High Temperature MHD Cermet Fuel Core for Nuclear Electric Propulsion

    Directory of Open Access Journals (Sweden)

    Jian Song

    2018-04-01

    Full Text Available Nuclear electric propulsion (NEP offers unique advantages for the interplanetary exploration. The extremely high conversion efficiency of magnetohydrodynamics (MHD conversion nuclear reactor makes it a highly potential space power source in the future, especially for NEP systems. Research on ultra-high temperature reactor suitable for MHD power conversion is performed in this paper. Cermet is chosen as the reactor fuel after a detailed comparison with the (U,ZrC graphite-based fuel and mixed carbide fuel. A reactor design is carried out as well as the analysis of the reactor physics and thermal-hydraulics. The specific design involves fuel element, reactor core, and radiation shield. Two coolant channel configurations of fuel elements are considered and both of them can meet the demands. The 91 channel configuration is chosen due to its greater heat transfer performance. Besides, preliminary calculation of nuclear criticality safety during launch crash accident is also presented. The calculation results show that the current design can meet the safety requirements well.

  3. Analysis of recovery efficiency in high-temperature aquifer thermal energy storage: a Rayleigh-based method

    Science.gov (United States)

    Schout, Gilian; Drijver, Benno; Gutierrez-Neri, Mariene; Schotting, Ruud

    2014-01-01

    High-temperature aquifer thermal energy storage (HT-ATES) is an important technique for energy conservation. A controlling factor for the economic feasibility of HT-ATES is the recovery efficiency. Due to the effects of density-driven flow (free convection), HT-ATES systems applied in permeable aquifers typically have lower recovery efficiencies than conventional (low-temperature) ATES systems. For a reliable estimation of the recovery efficiency it is, therefore, important to take the effect of density-driven flow into account. A numerical evaluation of the prime factors influencing the recovery efficiency of HT-ATES systems is presented. Sensitivity runs evaluating the effects of aquifer properties, as well as operational variables, were performed to deduce the most important factors that control the recovery efficiency. A correlation was found between the dimensionless Rayleigh number (a measure of the relative strength of free convection) and the calculated recovery efficiencies. Based on a modified Rayleigh number, two simple analytical solutions are proposed to calculate the recovery efficiency, each one covering a different range of aquifer thicknesses. The analytical solutions accurately reproduce all numerically modeled scenarios with an average error of less than 3 %. The proposed method can be of practical use when considering or designing an HT-ATES system.

  4. Thermal test of the insulation structure for LH 2 tank by using the large experimental apparatus

    Science.gov (United States)

    Kamiya, S.; Onishi, K.; Konshima, N.; Nishigaki, K.

    Conceptual designs of large mass LH 2 (liquid hydrogen) storage systems, whose capacity is 50,000 m3, have been studied in the Japanese hydrogen project, World Energy Network (WE-NET) [K. Fukuda, in: WE-NET Hydrogen Energy Symposium, 1999, P1-P41]. This study has concluded that their thermal insulation structures for the huge LH 2 tanks should be developed. Their actual insulation structures comprise not only the insulation material but also reinforced members and joints. To evaluate their thermal performance correctly, a large test specimen including reinforced members and joints will be necessary. After verifying the thermal performance of a developed large experimental apparatus [S. Kamiya, Cryogenics 40 (1) (2000) 35] for measuring the thermal conductance of various insulation structures, we tested two specimens, a vacuum multilayer insulation (MLI) with a glass fiber reinforced plastic (GFRP) support and a vacuum solid insulation (microtherm ®) with joints. The thermal background test for verifying the thermal design of the experimental apparatus showed that the background heat leak is 0.1 W, small enough to satisfy apparatus performance requirement. The thermal conductance measurements of specimens also showed that thermal heat fluxes of MLI with a GFRP support and microtherm ® are 8 and 5.4 W/m2, respectively.

  5.  Thermal Insulation System Made of Wood and Paper for Use in Residential Construction

    Science.gov (United States)

    Zoltán Pásztory; Tibor Horváth; Samuel V. Glass; Samuel L. Zelinka

    2015-01-01

    This article introduces an insulation system that takes advantage of the low thermal conductivity of still air and is made of wood and paper. The insulation, called the Mirrorpanel, is constructed as a panel of closely spaced layers of coated paper and held together in a frame of wood or fiberboard. Panels have been fabricated and tested at the laboratory scale, whole...

  6. Investigation of the sensitivity of MIS-sensor to thermal decomposition products of cables insulation

    Science.gov (United States)

    Filipchuk, D. V.; Litvinov, A. V.; Etrekova, M. O.; Nozdrya, D. A.

    2017-12-01

    Sensitivity of the MIS-sensor to products of thermal decomposition of insulation and jacket of the most common types of cables is investigated. It is shown that hydrogen is evolved under heating the insulation to temperatures not exceeding 250 °C. Registration of the evolved hydrogen by the MIS-sensor can be used for detection of fires at an early stage.

  7. Bionics in textiles: flexible and translucent thermal insulations for solar thermal applications.

    Science.gov (United States)

    Stegmaier, Thomas; Linke, Michael; Planck, Heinrich

    2009-05-13

    Solar thermal collectors used at present consist of rigid and heavy materials, which are the reasons for their immobility. Based on the solar function of polar bear fur and skin, new collector systems are in development, which are flexible and mobile. The developed transparent heat insulation material consists of a spacer textile based on translucent polymer fibres coated with transparent silicone rubber. For incident light of the visible spectrum the system is translucent, but impermeable for ultraviolet radiation. Owing to its structure it shows a reduced heat loss by convection. Heat loss by the emission of long-wave radiation can be prevented by a suitable low-emission coating. Suitable treatment of the silicone surface protects it against soiling. In combination with further insulation materials and flow systems, complete flexible solar collector systems are in development.

  8. Evaluation of thermal displacement behavior of high temperature piping system in power-up test of HTTR. No. 1 results up to 20 MW operation

    International Nuclear Information System (INIS)

    Hanawa, Satoshi; Kojima, Takao; Sumita, Junya; Tachibana, Yukio

    2002-03-01

    Temperature of the primary cooling system of the High Temperature Engineering Test Reactor, HTTR, becomes very high because the coolant temperature at the reactor outlet reaches 950degC, and 400degC at inlet of the reactor. Therefore, it is important to confirm the thermal displacement behavior of the high temperature piping system in the primary cooling system from the viewpoint of the structural integrity. Moreover, newly designed 3-dimensional floating support system is adopted to the cooling system, it is meaningful to verify the thermal displacement behavior of the piping system applied the 3-dimensional floating support system. In the power-up test (up to 20 MW operation), thermal displacement behavior of the high temperature piping system was measured. This paper describes the experimental and analytical results of thermal displacement characteristics of the high temperature piping system. The results showed that the resistance force induced from the supporting system effects to the thermal displacement behavior of cooling system, and the analytical results have a good agreement with the experimental results by optimizing the resistant force of the floating support system. Additionally, structural integrity at the 30 MW operation was confirmed by the analysis. (author)

  9. Influence of iron on crystallization behavior and thermal stability of the insulating materials - porous calcium silicates

    DEFF Research Database (Denmark)

    Haastrup, Sonja; Yu, Donghong; Yue, Yuanzheng

    2017-01-01

    The properties of porous calcium silicate for high temperature insulation are strongly influenced by impurities. In this work we determine the influence of Fe3+ on the crystallization behavior and thermal stability of hydrothermally derived calcium silicate. We synthesize porous calcium silicate...... with Ca/Si molar ratio of 1, to which Fe2O3 is added with Fe/Si molar ratios of 0.1, 0.5, 0.7, 1.0, and 1.3%. Structure and morphology of the porous calcium silicate, with different iron concentrations, are investigated using Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). FTIR...... measurements reveal a pronounced decrease in the number of Q3 sites in the calcium silicate with an increase of Fe3+, and thereby lower the crystal fraction of xonotlite (Ca6Si6O17(OH)2) phase, and increase the crystal fractions of tobermorite(Ca5Si6O16(OH)2·4H2O) and calcite (CaCO3) phases, as confirmed...

  10. Thermal highly porous insulation materials made of mineral raw materials

    Science.gov (United States)

    Mestnikov, A.

    2015-01-01

    The main objective of the study is to create insulating foam based on modified mineral binders with rapid hardening. The results of experimental studies of the composition and properties of insulating foam on the basis of rapidly hardening Portland cement (PC) and gypsum binder composite are presented in the article. The article proposes technological methods of production of insulating foamed concrete and its placement to the permanent shuttering wall enclosures in monolithic-frame construction and individual energy-efficient residential buildings, thus reducing foam shrinkage and improving crack-resistance.

  11. Thermal performance measurement and application of a multilayer insulator for emergency architecture

    International Nuclear Information System (INIS)

    Salvalai, Graziano; Imperadori, Marco; Scaccabarozzi, Diego; Pusceddu, Cristina

    2015-01-01

    Lightness coupled with a quick assembly method is crucial for emergency architecture in post-disaster area where accessibility and action time play a huge barer to rescue people. In this prospective, the following work analyses the potentiality (technological and thermal performances) of multilayer insulator for a new shelter envelope able to provide superior thermal comfort for the users. The thermal characteristics are derived experimentally by means of a guard ring apparatus under different working temperatures. Tests are performed on the multilayer insulator itself and on a composite structure, made of the multilayer insulator and two air gaps wrapped by a polyester cover, which is the core of a new lightweight emergency architecture. Experimental results show good agreement with literature data, providing a thermal conductivity and transmittance of about 0.04 W/(m °C) and 1.6 W/(m 2  °C) for the tested multilayer. The composite structure called Thermo Reflective Multilayer System (TRMS) shows better insulation performances, providing a thermal transmittance set to 0.85 W/(m 2  °C). A thermal model of an emergency tent based on the new insulating structure (TRMS) has been developed and its thermal performances have been compared with those of a UNHCR traditional emergency shelter. The shelter model was simulated (Trnsys v.17 environment) in the winter season considering the climate of Belgrade and using only the casual gains from occupant and solar radiation through opaque wall. Numerical simulations evidenced that the new insulating composite envelope reduces required heating load of about two and four times with respect to the traditional insulation. The study sets a starting point to develop a lightweight emergency architecture made with a combination between multilayer, air, polyester and vulcanized rubber. - Highlights: • Multilayer insulator tested by means of a guard ring apparatus. • Thermo reflective multilayer system (TRMS) development

  12. Design and assembly technology for the thermal insulation of the W7-X cryostat

    Energy Technology Data Exchange (ETDEWEB)

    Risse, K., E-mail: konrad.risse@ipp.mpg.de [Max-Planck-Institut fuer Plasmaphysik (IPP), Euratom Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Nagel, M.; Pietsch, M.; Braatz, A. [Max-Planck-Institut fuer Plasmaphysik (IPP), Euratom Association, Wendelsteinstrasse 1, D-17491 Greifswald (Germany); Binni, A. [MAN Diesel and Turbo SE, Dpt. OSA, Werftstrasse 17, D-94469 Deggendorf (Germany); Posselt, H. [Linde AG Engineering Div., Dr.-Carl-von-Linde-Strasse 6-14, D-82049 Hoellriegelskreuth (Germany)

    2011-10-15

    The Max-Planck-Institut fuer Plasmaphysik in Greifswald is building up the stellarator fusion experiment Wendelstein 7-X (W7-X). To operate the superconducting magnet system the vacuum and the cold structures are protected by a thermal insulated cryostat. The plasma vessel forms the inner cryostat wall, the outer wall is realised by a thermal insulated outer vessel. In addition 254 thermal insulated ports are fed through the cryogenic vacuum to allow the access to the plasma vessel for heating systems, supply lines or plasma diagnostics. The thermal insulation is being manufactured and assembled by MAN Diesel and Turbo SE (Germany). It consists of a multi-layer insulation (MLI) made of aluminized Kapton with a silk like fibreglass spacer and a thermal shield covering the inner cryostat surfaces. The shield on the plasma vessel is made of fibreglass reinforced epoxy resin with integrated copper meshes. The outer vessel insulation is made of brass panels with an average size of 3.3 x 2.0 m{sup 2}. Cooling loops made of stainless steel are connected via copper strips to the brass panels. Especially the complex 3 D shape of the plasma vessel, the restricted space inside the cryostat and the consideration of the operational component movements influenced the design work heavily. The manufacturing and the assembly has to fulfil stringent geometrical tolerances e.g. for the outer vessel panels +3/-2 mm.

  13. Design and assembly technology for the thermal insulation of the W7-X cryostat

    International Nuclear Information System (INIS)

    Risse, K.; Nagel, M.; Pietsch, M.; Braatz, A.; Binni, A.; Posselt, H.

    2011-01-01

    The Max-Planck-Institut fuer Plasmaphysik in Greifswald is building up the stellarator fusion experiment Wendelstein 7-X (W7-X). To operate the superconducting magnet system the vacuum and the cold structures are protected by a thermal insulated cryostat. The plasma vessel forms the inner cryostat wall, the outer wall is realised by a thermal insulated outer vessel. In addition 254 thermal insulated ports are fed through the cryogenic vacuum to allow the access to the plasma vessel for heating systems, supply lines or plasma diagnostics. The thermal insulation is being manufactured and assembled by MAN Diesel and Turbo SE (Germany). It consists of a multi-layer insulation (MLI) made of aluminized Kapton with a silk like fibreglass spacer and a thermal shield covering the inner cryostat surfaces. The shield on the plasma vessel is made of fibreglass reinforced epoxy resin with integrated copper meshes. The outer vessel insulation is made of brass panels with an average size of 3.3 x 2.0 m 2 . Cooling loops made of stainless steel are connected via copper strips to the brass panels. Especially the complex 3 D shape of the plasma vessel, the restricted space inside the cryostat and the consideration of the operational component movements influenced the design work heavily. The manufacturing and the assembly has to fulfil stringent geometrical tolerances e.g. for the outer vessel panels +3/-2 mm.

  14. Thermal characteristic of insulation for optimum design of RI transport package

    International Nuclear Information System (INIS)

    Lee, J. C.; Bang, K. S.; Seo, K. S.

    2002-01-01

    A package to transport the high level radioactive materials in required to withstand the hypothetical accident conditions as well as normal transport conditions according to IAEA and domestic regulations. The regulations require that the package should maintain the shielding, thermal and structural integrities to release no radioactive material. Thermal characteristics of insulations were evaluated and optimum insulation thickness was deduced for RI transport package. The package has a maximum capacity of 600 Curies for Ir-192 sealed source. The insulation thickness was decided with 10 mm of polyurethane form to maintain the thermal safety under fire accident condition. Thermal analysis was carried out for RI transport package, and it was shown that the thermal integrity of the package was maintained. The results obtained this study will be applied to a basic data for design of RI transport cask

  15. Temperature and press load stimulation on thermal transport in fibrous and porous composite insulators

    International Nuclear Information System (INIS)

    Rehman, M.A.; Maqsood, A.

    2006-01-01

    Thermal transport properties of synthetic pliable insulators are measured as a function of applied pressure at constant temperatures. Advantageous Transient Plane Source (ATPS) method is used for the simultaneous measurement of thermal conductivity and thermal diffusivity of these materials and heat capacity per unit volume is then calculated. Three samples namely foam, closed cell foam and fiber glass are subjected to press load, taking into account the flexibility and sustainability of the samples and the requirements of the technique used. The thermal data of the samples were determined within the temperature range (300-414K) and pressure range (Normal -15kPa). These materials are used for thermal insulation and temperature control of air-conditioned space, acoustic and sound insulation, agriculture and fishery, sports and leisure goods, building and civil engineering, industrial packaging cold storage ware house, boiler work and other electric appliances, so they are helpful in reducing energy losses. (author)

  16. A Facile Approach to Evaluate Thermal Insulation Performance of Paper Cups

    Directory of Open Access Journals (Sweden)

    Yudi Kuang

    2015-01-01

    Full Text Available Paper cups are ubiquitous in daily life for serving water, soup, coffee, tea, and milk due to their convenience, biodegradability, recyclability, and sustainability. The thermal insulation performance of paper cups is of significance because they are used to supply hot food or drinks. Using an effective thermal conductivity to accurately evaluate the thermal insulation performance of paper cups is complex due to the inclusion of complicated components and a multilayer structure. Moreover, an effective thermal conductivity is unsuitable for evaluating thermal insulation performance of paper cups in the case of fluctuating temperature. In this work, we propose a facile approach to precisely analyze the thermal insulation performance of paper cups in a particular range of temperature by using an evaluation model based on the MISO (Multiple-Input Single-Output technical theory, which includes a characterization parameter (temperature factor and a measurement apparatus. A series of experiments was conducted according to this evaluation model, and the results show that this evaluation model enables accurate characterization of the thermal insulation performance of paper cups and provides an efficient theoretical basis for selecting paper materials for paper cups.

  17. Thermal-permeability structure and recharge conditions of the Mutnovsky high-temperature geothermal field (Kamchatka, Russia)

    Science.gov (United States)

    Kiryukhin, A. V.; Polyakov, A. Y.; Usacheva, O. O.; Kiryukhin, P. A.

    2018-05-01

    The Mutnovsky geothermal area is part of the Eastern Kamchatka active volcano belt. Mutnovsky, 80 kY old and an aging strato-volcano (a complex of 4 composite volcanic cones), acts as a magma- and water-injector into the 25-km-long North Mutnovsky extension zone. Magmatic injection events (dykes) are associated with plane-oriented MEQ (Micro Earth Quakes) clusters, most of them occurring in the NE sector of the volcano (2 × 10 km2) at elevations from -4 to -2 km, while some magmatic injections occur at elevations from -6.0 to -4.0 km below the Mutnovsky production field. Water recharge of production reservoirs is from the Mutnovsky volcano crater glacier (+1500 to +1800 masl), which was confirmed by water isotopic data (δD, δ18O) of production wells at an earlier stage of development. The Mutnovsky (Dachny) 260-310 °C high-temperature production geothermal reservoir with a volume of 16 km3 is at the junction of NNE- and NE-striking normal faults, which coincides with the current dominant dyke injection orientation. TOUGH2-modeling estimates of the reservoir properties are as follows: the reservoir permeability is 90-600 e-15 m2, the deep upflow recharge is 80 kg/s and the enthalpy is 1420 kJ/kg. Modeling was used to reproduce the history of the Mutnovsky (Dachny) reservoir exploitation since 1983 with an effective power of 48 MWe by 2016. Modeling also showed that the reservoir is capable of yielding 65-83 MWe of sustainable production until 2055, if additional production drilling in the SE part of the field is performed. Moreover, this power value may increase to 87-105 MWe if binary technologies are applied. Modeling also shows that the predicted power is sensitive to local meteoric water influx during development. Conceptual iTOUGH2-EOS1sc thermal hydrodynamic modeling of the Mutnovsky magma-hydrothermal system as a whole reasonably explains its evolution over the last 1500-5000 years in terms of heat recharge (dyke injection from the Mutnovsky-4 funnel) and

  18. Fabrication of Ge-on-insulator wafers by Smart-CutTM with thermal management for undamaged donor Ge wafers

    Science.gov (United States)

    Kim, Munho; Cho, Sang June; Jayeshbhai Dave, Yash; Mi, Hongyi; Mikael, Solomon; Seo, Jung-Hun; Yoon, Jung U.; Ma, Zhenqiang

    2018-01-01

    Newly engineered substrates consisting of semiconductor-on-insulator are gaining much attention as starting materials for the subsequent transfer of semiconductor nanomembranes via selective etching of the insulating layer. Germanium-on-insulator (GeOI) substrates are critically important because of the versatile applications of Ge nanomembranes (Ge NMs) toward electronic and optoelectronic devices. Among various fabrication techniques, the Smart-CutTM technique is more attractive than other methods because a high temperature annealing process can be avoided. Another advantage of Smart-CutTM is the reusability of the donor Ge wafer. However, it is very difficult to realize an undamaged Ge wafer because there exists a large mismatch in the coefficient of thermal expansion among the layers. Although an undamaged donor Ge wafer is a prerequisite for its reuse, research related to this issue has not yet been reported. Here we report the fabrication of 4-inch GeOI substrates using the direct wafer bonding and Smart-CutTM process with a low thermal budget. In addition, a thermo-mechanical simulation of GeOI was performed by COMSOL to analyze induced thermal stress in each layer of GeOI. Crack-free donor Ge wafers were obtained by annealing at 250 °C for 10 h. Raman spectroscopy and x-ray diffraction (XRD) indicated similarly favorable crystalline quality of the Ge layer in GeOI compared to that of bulk Ge. In addition, Ge p-n diodes using transferred Ge NM indicate a clear rectifying behavior with an on and off current ratio of 500 at ±1 V. This demonstration offers great promise for high performance transferrable Ge NM-based device applications.

  19. Vibrometry Assessment of the External Thermal Composite Insulation Systems Influence on the Façade Airborne Sound Insulation

    Directory of Open Access Journals (Sweden)

    Daniel Urbán

    2018-05-01

    Full Text Available This paper verifies the impact of the use of an external thermal composite system (ETICS on air-borne sound insulation. For optimum accuracy over a wide frequency range, classical microphone based transmission measurements are combined with accelerometer based vibrometry measurements. Consistency is found between structural resonance frequencies and bending wave velocity dispersion curves determined by vibrometry on the one hand and spectral features of the sound reduction index, the ETICS mass-spring-mass resonance induced dip in the acoustic insulation spectrum, and the coincidence induced dip on the other hand. Scanning vibrometry proves to be an effective tool for structural assessment in the design phase of ETICS systems. The measured spectra are obtained with high resolution in wide frequency range, and yield sound insulation values are not affected by the room acoustic features of the laboratory transmission rooms. The complementarity between the microphone and accelerometer based results allows assessing the effect of ETICS on the sound insulation spectrum in an extended frequency range from 20 Hz to 10 kHz. The modified engineering ΔR prediction model for frequency range up to coincidence frequency of external plaster layer is recommended. Values for the sound reduction index obtained by a modified prediction method are consistent with the measured data.

  20. The thermal insulation difference of clothing ensembles on the dry and perspiration manikins

    International Nuclear Information System (INIS)

    Xiaohong, Zhou; Chunqin, Zheng; Yingming, Qiang; Holmér, Ingvar; Gao, Chuansi; Kuklane, Kalev

    2010-01-01

    There are about a hundred manikin users around the world. Some of them use the manikin such as 'Walter' and 'Tore' to evaluate the comfort of clothing ensembles according to their thermal insulation and moisture resistance. A 'Walter' manikin is made of water and waterproof breathable fabric 'skin', which simulates the characteristics of human perspiration. So evaporation, condensation or sorption and desorption are always accompanied by heat transfer. A 'Tore' manikin only has dry heat exchange by conduction, radiation and convection from the manikin through clothing ensembles to environments. It is an ideal apparatus to measure the thermal insulation of the clothing ensemble and allows evaluation of thermal comfort. This paper compares thermal insulation measured with dry 'Tore' and sweating 'Walter' manikins. Clothing ensembles consisted of permeable and impermeable clothes. The results showed that the clothes covering the 'Walter' manikin absorbed the moisture evaporated from the manikin. When the moisture transferred through the permeable clothing ensembles, heat of condensation could be neglected. But it was observed that heavy condensation occurred if impermeable clothes were tested on the 'Walter' manikin. This resulted in a thermal insulation difference of clothing ensembles on the dry and perspiration manikins. The thermal insulation obtained from the 'Walter' manikin has to be modified when heavy condensation occurs. The modified equation is obtained in this study

  1. Geomechanical characterization of the Upper Carboniferous under thermal stress for the evaluation of a High Temperature - Mine Thermal Energy Storage (HT-MTES)

    Science.gov (United States)

    Hahn, Florian; Brüggemann, Nina; Bracke, Rolf; Alber, Michael

    2017-04-01

    The goal of this R&D project is to create a technically and economically feasible conceptual model for a High Temperature - Mine Thermal Energy Storage (HT-MTES) for the energetic reuse of a mine on the example of the Prosper-Haniel coal mine in Bottrop, Germany. This project is funded by the "Initiative Energy Storage" program of the German Federal Ministries BMWi, BMU and BMBF. At the end of 2018, the last operative coal mine in North Rhine-Westphalia, Germany (Prosper-Haniel), is going to be closed down, plugged and abandoned. Large amounts of subsurface infrastructures, resembled mainly by open parts of former galleries and mining faces are going to be flooded, after the mine is closed down and therefore have the potential to become an enormous geothermal reservoir for a seasonal heat storage. During the summer non-used (waste) heat from solar thermal power plants, garbage incineration, combined heat and power plants (CHP) or industrial production processes can be stored within dedicated drifts of the mine. During the winter season, this surplus heat can be extracted and directly utilized in commercial and/or residential areas. For the evaluation of such a HT-MTES within a former coal mine, the corresponding geomechanical parameters of the Upper Carboniferous under thermal stress needs to be evaluated. Therefore the main rock types of the Upper Carboniferous (claystone, siltstone and sandstone) are subject to a geomechanical characterization before and after thermal cyclic loadings of temperatures up to 200 °C. The samples have been collected directly from the coal mine Prosper-Haniel within a depth range of 1000 - 1200 m. Unconfined compressive and tensile strengths, as well as triaxial tests were performed at room temperature. Furthermore, a range of petrophysical properties like density, thin-section analysis and P-wave velocities were determined. First results show an indication that the overall strength properties of the samples are not effected by

  2. Effect of thermal insulation on the electrical characteristics of NbOx threshold switches

    Science.gov (United States)

    Wang, Ziwen; Kumar, Suhas; Wong, H.-S. Philip; Nishi, Yoshio

    2018-02-01

    Threshold switches based on niobium oxide (NbOx) are promising candidates as bidirectional selector devices in crossbar memory arrays and building blocks for neuromorphic computing. Here, it is experimentally demonstrated that the electrical characteristics of NbOx threshold switches can be tuned by engineering the thermal insulation. Increasing the thermal insulation by ˜10× is shown to produce ˜7× reduction in threshold current and ˜45% reduction in threshold voltage. The reduced threshold voltage leads to ˜5× reduction in half-selection leakage, which highlights the effectiveness of reducing half-selection leakage of NbOx selectors by engineering the thermal insulation. A thermal feedback model based on Poole-Frenkel conduction in NbOx can explain the experimental results very well, which also serves as a piece of strong evidence supporting the validity of the Poole-Frenkel based mechanism in NbOx threshold switches.

  3. Thermal transport across metal–insulator interface via electron–phonon interaction

    International Nuclear Information System (INIS)

    Zhang, Lifa; Wang, Jian-Sheng; Li, Baowen; Lü, Jing-Tao

    2013-01-01

    The thermal transport across a metal–insulator interface can be characterized by electron–phonon interaction through which an electron lead is coupled to a phonon lead if phonon–phonon coupling at the interface is very weak. We investigate the thermal conductance and rectification between the electron part and the phonon part using the nonequilibrium Green’s function method. It is found that the thermal conductance has a nonmonotonic behavior as a function of average temperature or the coupling strength between the phonon leads in the metal part and the insulator part. The metal–insulator interface shows a clear thermal rectification effect, which can be reversed by a change in average temperature or the electron–phonon coupling. (paper)

  4. 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

  5. Foam/Aerogel Composite Materials for Thermal and Acoustic Insulation and Cryogen Storage

    Science.gov (United States)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Weiser, Erik S. (Inventor); Sass, Jared P. (Inventor)

    2011-01-01

    The invention involves composite materials containing a polymer foam and an aerogel. The composite materials have improved thermal insulation ability, good acoustic insulation, and excellent physical mechanical properties. The composite materials can be used, for instance, for heat and acoustic insulation on aircraft, spacecraft, and maritime ships in place of currently used foam panels and other foam products. The materials of the invention can also be used in building construction with their combination of light weight, strength, elasticity, ability to be formed into desired shapes, and superior thermal and acoustic insulation power. The materials have also been found to have utility for storage of cryogens. A cryogenic liquid or gas, such as N.sub.2 or H.sub.2, adsorbs to the surfaces in aerogel particles. Thus, another embodiment of the invention provides a storage vessel for a cryogen.

  6. Thermal performance of an insulating structure for a reactor vessel

    International Nuclear Information System (INIS)

    Aranovitch, E.; Crutzen, S.; LeDet, M.; Denis, R.

    This report describes the installations used to test the HTGR reactor vessel insulating structure called ''Casali'' and details the experimental results in 3 groups: general experiments, systematic study, and technological experiments. The results obtained make it possible to satisfactorily predict the behavior of the structure in a practical application

  7. Technological improvements to high temperature thermocouples for nuclear reactor applications

    International Nuclear Information System (INIS)

    Schley, R.; Leveque, J.P.

    1980-07-01

    The specific operating conditions of thermocouples in nuclear reactors have provided an incentive for further advances in high temperature thermocouple applications and performance. This work covers the manufacture and improvement of existing alloys, the technology of clad thermocouples, calibration drift during heat treatment, resistance to thermal shock and the compatibility of insulating materials with thermo-electric alloys. The results lead to specifying improved operating conditions for thermocouples in nuclear reactor media (pressurized water, sodium, uranium oxide) [fr

  8. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    International Nuclear Information System (INIS)

    Kuijper, J.C.; Somers, J.; Van Den Durpel, L.

    2013-01-01

    The PUMA project - the acronym stands for “Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors” - was a Specific Targeted Research Project (STREP) within the Euratom 6th Framework (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO2-free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR designs and their ability to accept a variety

  9. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    International Nuclear Information System (INIS)

    Kuijper, J.C.; Somers, J.; Van Den Durpel, L.; Chauvet, V.; Cerullo, N.; Cetnar, J.; Abram, T.; Bakker, K.; Bomboni, E.; Bernnat, W.; Domanska, J.G.; Girardi, E.; De Haas, J.B.M.; Hesketh, K.; Hiernaut, J.P.; Hossain, K.; Jonnet, J.; Kim, Y.; Kloosterman, J.L.; Kopec, M.; Murgatroyd, J.; Millington, D.; Lecarpentier, D.; Lomonaco, G.; McEachern, D.; Meier, A.; Mignanelli, M.; Nabielek, H.; Oppe, J.; Petrov, B.Y.; Pohl, C.; Ruetten, H.J.; Schihab, S.; Toury, G.; Trakas, C.; Venneri, F.; Verfondern, K.; Werner, H.; Wiss, T.; Zakova, J.

    2010-11-01

    The PUMA project -the acronym stands for 'Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors'- was a Specific Targeted Research Project (STREP) within the EURATOM 6th Framework Program (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO 2 -free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR designs and their ability to accept a

  10. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    Energy Technology Data Exchange (ETDEWEB)

    Kuijper, J.C., E-mail: kuijper@nrg.eu [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Somers, J; Van Den Durpel, L; Chauvet, V; Cerullo, N; Cetnar, J; Abram, T; Bakker, K; Bomboni, E; Bernnat, W; Domanska, J G; Girardi, E; De Haas, J B.M.; Hesketh, K; Hiernaut, J P; Hossain, K; Jonnet, J; Kim, Y; Kloosterman, J L; Kopec, M; Murgatroyd, J; Millington, D; Lecarpentier, D; Lomonaco, G; McEachern, D; Meier, A; Mignanelli, M; Nabielek, H; Oppe, J; Petrov, B Y; Pohl, C; Ruetten, H J; Schihab, S; Toury, G; Trakas, C; Venneri, F; Verfondern, K; Werner, H; Wiss, T; Zakova, J

    2010-11-15

    The PUMA project -the acronym stands for 'Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors'- was a Specific Targeted Research Project (STREP) within the EURATOM 6th Framework Program (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO{sub 2}-free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR designs and their ability to accept a

  11. Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors. Publishable Final Activity Report

    Energy Technology Data Exchange (ETDEWEB)

    Kuijper, J.C., E-mail: kuijper@nrg.eu [Nuclear Research and Consultancy Group (NRG), Petten (Netherlands); Somers, J.; Van Den Durpel, L.; Chauvet, V.; Cerullo, N.; Cetnar, J.; Abram, T.; Bakker, K.; Bomboni, E.; Bernnat, W.; Domanska, J.G.; Girardi, E.; De Haas, J.B.M.; Hesketh, K.; Hiernaut, J.P.; Hossain, K.; Jonnet, J.; Kim, Y.; Kloosterman, J.L.; Kopec, M.; Murgatroyd, J.; Millington, D.; Lecarpentier, D.; Lomonaco, G.; McEachern, D.; Meier, A.; Mignanelli, M.; Nabielek, H.; Oppe, J.; Petrov, B.Y.; Pohl, C.; Ruetten, H.J.; Schihab, S.; Toury, G.; Trakas, C.; Venneri, F.; Verfondern, K.; Werner, H.; Wiss, T.; Zakova, J.

    2010-11-15

    The PUMA project -the acronym stands for 'Plutonium and Minor Actinide Management in Thermal High-Temperature Gas-Cooled Reactors'- was a Specific Targeted Research Project (STREP) within the EURATOM 6th Framework Program (EU FP6). The PUMA project ran from September 1, 2006, until August 31, 2009, and was executed by a consortium of 14 European partner organisations and one from the USA. This report serves 2 purposes. It is both the 'Publishable Final Activity Report' and the 'Final (Summary) Report', describing, per Work Package, the specific objectives, research activities, main conclusions, recommendations and supporting documents. PUMA's main objective was to investigate the possibilities for the utilisation and transmutation of plutonium and especially minor actinides in contemporary and future (high temperature) gas-cooled reactor designs, which are promising tools for improving the sustainability of the nuclear fuel cycle. This contributes to the reduction of Pu and MA stockpiles, and also to the development of safe and sustainable reactors for CO{sub 2}-free energy generation. The PUMA project has assessed the impact of the introduction of Pu/MA-burning HTRs at three levels: fuel and fuel performance (modelling), reactor (transmutation performance and safety) and reactor/fuel cycle facility park. Earlier projects already indicated favourable characteristics of HTRs with respect to Pu burning. So, core physics of Pu/MA fuel cycles for HTRs has been investigated to study the CP fuel and reactor characteristics and to assure nuclear stability of a Pu/MA HTR core, under both normal and abnormal operating conditions. The starting point of this investigation comprised the two main contemporary HTR designs, viz. the pebble-bed type HTR, represented by the South-African PBMR, and hexagonal block type HTR, represented by the GT-MHR. The results (once again) demonstrate the flexibility of the contemporary (and near future) HTR

  12. Tunable metal-insulator transitions in bilayer graphene by thermal annealing

    OpenAIRE

    Kalon, Gopinadhan; Shin, Young Jun; Yang, Hyunsoo

    2012-01-01

    Tunable and highly reproducible metal-insulator transitions have been observed in bilayer graphene upon thermal annealing at 400 K under high vacuum conditions. Before annealing, the sample is metallic in the whole temperature regime of study. Upon annealing, the conductivity changes from metallic to that of an insulator and the transition temperature is a function of annealing time. The pristine metallic state can be reinstated by exposing to air thereby inducing changes in the electronic pr...

  13. Thermal response of core and central-cavity components of a high-temperature gas-cooled reactor in the absence of forced convection coolant flow

    International Nuclear Information System (INIS)

    Whaley, R.L.; Sanders, J.P.

    1976-09-01

    A means of determining the thermal responses of the core and the components of a high-temperature gas-cooled reactor after loss of forced coolant flow is discussed. A computer program, using a finite-difference technique, is presented together with a solution of the confined natural convection. The results obtained are reasonable and demonstrate that the computer program adequately represents the confined natural convection

  14. More with thermal energy storage. Report 6. High temperature storage. Overview of knowledge and results of measurements with regard to high temperature storage systems. Final report; Meer met bodemenergie. Rapport 6. Hogetemperatuuropslag. Kennisoverzicht en praktijkmetingen rondom hogetemperatuuropslagsystemen. Eindrapport

    Energy Technology Data Exchange (ETDEWEB)

    Drijver, B. [IF Technology, Arnhem (Netherlands)

    2012-03-30

    The project More With Thermal Energy Storage (MMB, abbreviated in Dutch) focuses on knowledge gaps and potential opportunities regarding open systems. The main questions to be answered are: (1) What effects (hydrological, thermal, microbiological and chemical) occur in the soil system by application of thermal energy storage; (2) Which technical options are available for a sustainable integration of thermal energy storage in the water and energy chain?; (3) Is it possible to achieve multiple objectives by using smart combinations? The project is organized in different work packages. In work package 2, the effects of individual and collective thermal energy storage storage systems on subsoils and the environment are determined. In work package 3 the opportunities for thermal energy storage and soil remediation are examined, while in work package 4 the focus is on new sustainable combinations of heat and cold storage. Work package 1 is the umbrella part where communication and policy of and participation in MMB are the main subjects. This report includes the results of research in the field of high temperature heat storage. Residual heat, which comes available in the summer can be used for heating purposes in the winter. To realize that heat can be stored temporarily. It appears that the subsurface can be used, which has resulted in a strong growth of heat and cold storage systems [Dutch] Het project Meer Met Bodemenergie (MMB) richt zich op het invullen van kennisleemtes en mogelijke kansen ten aanzien van open systemen. De belangrijkste vragen waarop het onderzoeksprogramma MMB antwoord geeft zijn: (1) Welke effecten (hydrologisch, thermisch, microbiologisch en chemisch) treden op in het bodemsysteem bij toepassing van bodemenergie?; (2) Welke technische mogelijkheden zijn er voor het duurzaam inpassen van bodem-energie in de water- en energieketen?; (3) Is het mogelijk om meerdere doelstellingen tegelijk te verwezenlijken door slimme combinaties te maken? Het

  15. Thermal paint production: the techno-economic evaluation of muscovite as insulating additive.

    Directory of Open Access Journals (Sweden)

    Gabriela Fernandes Ribas

    2016-09-01

    Full Text Available Muscovite is known by its thermal and electrical insulating properties. Based on this, it was hypothesized that its addition on paints should increase the thermal resistance. The use of muscovite as mineral insulating is pointed out as advantageous due to its low cost compared to other materials used for this purpose, such as the ceramic microsphere. The use of a low cost material could open the access to the medium and low income families, implying two aspects: the life quality increase by thermal comfort and the increase of energy saving. Thus, this part of the population could open a new market to thermal paints. Aiming to contribute to this issue, this work evaluated the thermal insulation performance of commercial paints containing muscovite additions and determined the economic evaluation for its industrial production. The thermal paint was formulated by adding 10%, 20% and 40% of muscovite to the commercial paint. This was applied on steel reinforced mortar boards. Thermal insulation tests were carried out in bench scale using an adapted box. The economic evaluation of the industrial production of muscovite-based thermal paint was conducted, considering the Brazilian economic market in this activity. The results showed its ability as an insulating agent due to a reduction of 0.667 °C/mm board by the addition of 40% muscovite. The economic analysis also demonstrated the feasibility of the thermal paint industrial production. The payback is favorable to 5 years when compared to the Selic short-term lending rate, with 21.53% of internal rate return and a net present value of US$ 15,085.76.

  16. Literature review of thermal and radiation performance parameters for high-temperature, uranium dioxide fueled cermet materials

    International Nuclear Information System (INIS)

    Haertling, C.; Hanrahan, R.J.

    2007-01-01

    High-temperature fissile-fueled cermet literature was reviewed. Data are presented primarily for the W-UO 2 as this was the system most frequently studied; other reviewed systems include cermets with Mo, Re, or alloys as a matrix. Failure mechanisms for the cermets are typically degradation of mechanical integrity and loss of fuel. Mechanical failure can occur through stresses produced from dissimilar expansion coefficients, voids created from diffusion of dissimilar materials or formation of metal hydride and subsequent volume expansion. Fuel loss failure can occur by high temperature surface vaporization or by vaporization after loss of mechanical integrity. Techniques found to aid in retaining fuel include the use of coatings around UO 2 fuel particles, use of oxide stabilizers in the UO 2 , minimizing grain sizes in the metal matrix, minimizing impurities, controlling the cermet sintering atmosphere, and cladding around the cermet

  17. The Modeling and Simulation of Thermal Analysis at Hydro Generator Stator Winding Insulation

    Directory of Open Access Journals (Sweden)

    Mihaela Raduca

    2006-10-01

    Full Text Available This paper presents the modelling and simulation of thermal analysis at hydro generator stator winding. The winding stator is supplied at high voltage of 11 kV for high power hydro generator. To present the thermal analysis for stator winding is presented at supply of coil by 11 kV, when coil is heat and thermal transfer in insulation at ambient temperature.

  18. The use of salinity contrast for density difference compensation to improve the thermal recovery efficiency in high-temperature aquifer thermal energy storage systems

    Science.gov (United States)

    van Lopik, Jan H.; Hartog, Niels; Zaadnoordijk, Willem Jan

    2016-08-01

    The efficiency of heat recovery in high-temperature (>60 °C) aquifer thermal energy storage (HT-ATES) systems is limited due to the buoyancy of the injected hot water. This study investigates the potential to improve the efficiency through compensation of the density difference by increased salinity of the injected hot water for a single injection-recovery well scheme. The proposed method was tested through numerical modeling with SEAWATv4, considering seasonal HT-ATES with four consecutive injection-storage-recovery cycles. Recovery efficiencies for the consecutive cycles were investigated for six cases with three simulated scenarios: (a) regular HT-ATES, (b) HT-ATES with density difference compensation using saline water, and (c) theoretical regular HT-ATES without free thermal convection. For the reference case, in which 80 °C water was injected into a high-permeability aquifer, regular HT-ATES had an efficiency of 0.40 after four consecutive recovery cycles. The density difference compensation method resulted in an efficiency of 0.69, approximating the theoretical case (0.76). Sensitivity analysis showed that the net efficiency increase by using the density difference compensation method instead of regular HT-ATES is greater for higher aquifer hydraulic conductivity, larger temperature difference between injection water and ambient groundwater, smaller injection volume, and larger aquifer thickness. This means that density difference compensation allows the application of HT-ATES in thicker, more permeable aquifers and with larger temperatures than would be considered for regular HT-ATES systems.

  19. Characterization of systems for external insulation and retrofitting with emphasis on the thermal performance

    DEFF Research Database (Denmark)

    Rudbeck, Claus; Rose, Jørgen

    1999-01-01

    During the last decade retrofitting of buildings has received increased attention not only in northern Europe but throughout the world. Retrofitting of buildings is usually performed to solve one or more of the following problems: poor indoor climate, excessive heat losses, insufficient durability...... a building designer with such a choice, key parameters for insulation systems are described in a uniform manner stating their performance with regards to aesthetics, heat transfer, moisture, durability, fire and economy. Parameters given for the total insulation capability enable the building designer...... to include the effect of thermal bridges by performing simple calculations, a task which normally requires the use of numerical models. The results show that thermal bridges in external insulation systems may decrease their thermal resistance by more than 25%.Key parameters was calculated by the use...

  20. Mass separation of rare-earth elements by a high-temperature thermal ion source coupled with a He-jet system

    International Nuclear Information System (INIS)

    Kawase, Y.; Okano, K.; Aoki, K.

    1987-01-01

    By using a high-temperature thermal ion source coupled to a He-jet system, neutron-rich isotopes of rare-earth elements such as cerium, praseodymium, neodymium and promethium produced by the thermal-neutron fission of /sup 235/U were ionized and successfully separated. The temperature dependence of the ionization efficiency has been measured and found to be explained qualitatively by the vapour pressure of the relevant elements. The characteristic temperature dependence of the ionization efficiency has been utilized for Z-identification of several isobars of rare-earth elements. The heaviest isotopes of neodymium and promethium, /sup 155/Nd and /sup 156/Pm, have recently been identified

  1. Effect of thermal-treatment sequence on sound absorbing and mechanical properties of porous sound-absorbing/thermal-insulating composites

    Directory of Open Access Journals (Sweden)

    Huang Chen-Hung

    2016-01-01

    Full Text Available Due to recent rapid commercial and industrial development, mechanical equipment is supplemented massively in the factory and thus mechanical operation causes noise which distresses living at home. In livelihood, neighborhood, transportation equipment, jobsite construction noises impact on quality of life not only factory noise. This study aims to preparation technique and property evaluation of porous sound-absorbing/thermal-insulating composites. Hollow three-dimensional crimp PET fibers blended with low-melting PET fibers were fabricated into hollow PET/low-melting PET nonwoven after opening, blending, carding, lapping and needle-bonding process. Then, hollow PET/low-melting PET nonwovens were laminated into sound-absorbing/thermal-insulating composites by changing sequence of needle-bonding and thermal-treatment. The optimal thermal-treated sequence was found by tensile strength, tearing strength, sound-absorbing coefficient and thermal conductivity coefficient tests of porous composites.

  2. Experimental assessment of improvements in thermal performance from insulating the thermal bridge at the edge of a floor slab

    Directory of Open Access Journals (Sweden)

    N. Arias Jiménez

    2017-06-01

    Full Text Available The problematic of the article rises from the need of improving the thermal quality of the built envelope in the wall complex, specifically in the case of reinforced concrete (most used material in high-rise housing in Chile. Considering the use of insulation on the inside face of the wall, interrupts the continuity of the insulating material where the mezzanine slab and the perimeter walls meet, generating a thermal bridge known as mezzanine front. The purpose then, is to know the impact of the mentioned thermal bridge studying its properties through experimental tests on a thermal chamber. Later, the results will be integrated to a case of study that allows establishing the incidence of the bridge in the overall energetic behavior of through the integration of the results into the Thermal Analysis Simulation software (Tas. Finally, it is concluded a low incidence in the inner heat loses, becoming relevant the behavior of the superficial temperatures.

  3. Thermal insulating system particularly adapted for building construction

    International Nuclear Information System (INIS)

    Dyar, H.G.

    1985-01-01

    This disclosure relates to an insulating system which is particularly adapted for insulating the walls, floors, ceilings and like structure of buildings and includes a panel having a hollow chamber or interior under negative pressure (vacuum) and being of a variety of external peripheral sizes and shapes to fit within areas defined by wall and/or floor and/or ceiling studs, beams, or the like, a plurality of springs, chains or the like for supporting the panel in generally spaced relationship to an associated building wall, ceiling, floor or like structure, and a plurality of pin-like elements of relatively small cross-sectional configuration normally spaced from the exterior surface of the panel for contacting a limited exterior surface area of the panel only upon the springs, chains or the like becoming inoperative which would in the absence of the pin-like elements result in direct contact between the panel and the associated building wall, ceiling, floor or like structure and thus reduce the insulating efficiency thereof

  4. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation

    Directory of Open Access Journals (Sweden)

    Mohamad Irfan Fathurrohman

    2015-07-01

    Full Text Available The vulcanization kinetics of Ethylene-propylene diene monomer (EPDM rubber thermal insulation was studied by using rheometer under isothermal condition at different temperatures. The rheometry analysis was used to determining the cure kinetic parameters and predicting the cure time of EPDM thermal insulation. The experimental results revealed that the curing curves of EPDM thermal insulation were marching and the optimum curing time decreased with increasing the temperature. The kinetic parameters were determined from the autocatalytic model showed close fitting with the experimental results, indicating suitability of autocatalytic model in characterizing the cure kinetics. The activation energy was determined from the autocatalytic model is 46.3661 kJ mol-1. The cure time were predicted from autocatalytic model and the obtained kinetic parameter by using the relationship among degree of conversion, cure temperature, and cure time. The predictions of cure time provide information for the actual curing characteristic of EPDM thermal insulation. The mechanical properties of EPDM thermal insulation with different vulcanization temperatures showed the same hardness, tensile strength and modulus at 300%, except at temperature 70 °C, while the elongation at breaking point decreased with increasing temperature of vulcanization. © 2015 BCREC UNDIP. All rights reservedReceived: 8th April 2014; Revised: 7th January 2015; Accepted: 16th January 2015How to Cite: Fathurrohman, M.I., Maspanger, D.R., Sutrisno, S. (2015. Vulcanization Kinetics and Mechanical Properties of Ethylene Propylene Diene Monomer Thermal Insulation. Bulletin of Chemi-cal Reaction Engineering & Catalysis, 10 (2, 104-110. (doi:10.9767/bcrec.10.2.6682.104-110Permalink/DOI: http://dx.doi.org/10.9767/bcrec.10.2.6682.104-110 

  5. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    International Nuclear Information System (INIS)

    Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo

    2016-01-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO 2 ) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO 2 film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management

  6. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Ito, Kota, E-mail: kotaito@mosk.tytlabs.co.jp; Nishikawa, Kazutaka; Iizuka, Hideo [Toyota Central Research and Development Labs, Nagakute, Aichi 480-1192 (Japan)

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO{sub 2}) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO{sub 2} film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  7. Repairing the deteriorated thermal insulation in the serpentine - moderator tank - SLCD assemblies

    International Nuclear Information System (INIS)

    Gyongyosi, Tiberiu

    2004-01-01

    Deterioration during operation of the thermal insulation at the upper serpentines in the serpentine assembly in the moderator tank of SLCD (the system of localising the failed fuel) can create problems when one scans the fuel channels in case of failure of one of the ventilated air refrigerator in the rooms of the LAC 10 reactor. Recovering the thermal insulation is absolutely necessary but it is difficult to execute because the loading operation with the granulated layer of diatomaceous filtering agent must be effected directly on the moderator tank after some 24 h from the reactor shut down. The paper presents two possible methods of repairing together with the necessary technological facilities

  8. Improvement of the thermal behavior of linear motors through insulation layer

    International Nuclear Information System (INIS)

    Eun, I. U.; Lee, C. M.; Chung, W. J.; Choi, Y. H.

    2001-01-01

    Linear motors can drive a linear motion without intermediate gears, screws or crank shafts. Linear motors can successfully replace ball lead screw in machine tools, because they have a high velocity, acceleration and good positioning accuracy. On the other hand, linear motors emit large amounts of heat and have low efficiency. In this paper, heat sources of a synchronous linear motor with high velocity and force are measured and analyzed. To improve the thermal stiffness of the linear motor, an insulation layer with low thermal conductivity is inserted between cooler and machine table. Some effects of the insulation layer are presented

  9. Manufacturing a Long-Period Grating with Periodic Thermal Diffusion Technology on High-NA Fiber and Its Application as a High-Temperature Sensor.

    Science.gov (United States)

    Shen, Xiang; Dai, Bin; Xing, Yingbin; Yang, Luyun; Li, Haiqing; Li, Jinyan; Peng, Jingang

    2018-05-08

    We demonstrated a kind of long-period fiber grating (LPFG), which is manufactured with a thermal diffusion treatment. The LPFG was inscribed on an ultrahigh-numerical-aperture (UHNA) fiber, highly doped with Ge and P, which was able to easily diffuse at high temperatures within a few seconds. We analyzed how the elements diffused at a high temperature over 1300 °C in the UHNA fiber. Then we developed a periodically heated technology with a CO₂ laser, which was able to cause the diffusion of the elements to constitute the modulations of an LPFG. With this technology, there is little damage to the outer structure of the fiber, which is different from the traditional LPFG, as it is periodically tapered. Since the LPFG itself was manufactured under high temperature, it can withstand higher temperatures than traditional LPFGs. Furthermore, the LPFG presents a higher sensitivity to high temperature due to the large amount of Ge doping, which is approximately 100 pm/°C. In addition, the LPFG shows insensitivity to the changing of the environment’s refractive index and strain.

  10. Thermal spin current generation and spin transport in Pt/magnetic-insulator/Py heterostructures

    Science.gov (United States)

    Chen, Ching-Tzu; Safranski, Christopher; Krivorotov, Ilya; Sun, Jonathan

    Magnetic insulators can transmit spin current via magnon propagation while blocking charge current. Furthermore, under Joule heating, magnon flow as a result of the spin Seeback effect can generate additional spin current. Incorporating magnetic insulators in a spin-orbit torque magnetoresistive memory device can potentially yield high switching efficiencies. Here we report the DC magneto-transport studies of these two effects in Pt/magnetic-insulator/Py heterostructures, using ferrimagnetic CoFexOy (CFO) and antiferromagnet NiO as the model magnetic insulators. We observe the presence and absence of the inverse spin-Hall signals from the thermal spin current in Pt/CFO/Py and Pt/NiO/Py structures. These results are consistent with our spin-torque FMR linewidths in comparison. We will also report investigations into the magnetic field-angle dependence of these observations.

  11. High temperature x-ray diffraction of zr-2.5nb during thermal cycling in vacuum

    Directory of Open Access Journals (Sweden)

    Tumanov Mikhail

    2017-01-01

    Full Text Available The cyclic thermal tests in vacuum of zirconium alloy Zr-2.5Nb in the temperature range 250-350°C is established the presence of anomalies of thermal deformation of the crystal lattice, reducing the efficiency of the fuel rods.

  12. The experiment study of the thermal insulation of the roof-slab of the main vessel of a LMFBR

    International Nuclear Information System (INIS)

    Wang Zhifeng; Wang Zhou; Yang Xianyong

    1995-01-01

    The effects of composition of insulation, i.e., reflective multi-plate thermal insulator, protecting the roof-slab of the vessel of the LMFBR on the heat transfer performance has been studied experimentally for CEFR. A economical form of the thermal insulation is suggested for CEFR. In addition, the scheme without reflective thermal insulator which has only a forced convection cooling system has been studied experimentally and a formula to calculate the average Nusselt number of the flow channel, which is valuable for CEFR design, has been raised

  13. 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

  14. Minimization of thermal insulation thickness taking into account condensation on external walls

    Directory of Open Access Journals (Sweden)

    Nurettin Yamankaradeniz

    2015-09-01

    Full Text Available Condensation occurs in the inner layers of construction materials at whatever point the partial pressure of water vapor diffuses and reaches its saturation pressure. Condensation, also called sweating, damages materials, reduces thermal resistance, and by increasing the total heat transfer coefficient, results in unwanted events such as increased heat loss. This study applied minimization of thermal insulation thickness with consideration given to condensation in the external walls. The calculations of heat and mass transfers in the structure elements are expressed in a graphical form. While there was an increase in the required thermal insulation thickness subsequent to an increase in the internal environment’s temperature, relative humidity, and the external environment’s relative humidity, the required thickness decreased with an increase in the external environment’s temperature. The amount of water vapor transferred varied with internal or external conditions and the thickness of the insulation. A change in the vapor diffusion resistance of the insulation material can increase the risk of condensation on the internal or external surfaces of the insulation.

  15. Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide

    Science.gov (United States)

    Wicklein, Bernd; Kocjan, Andraž; Salazar-Alvarez, German; Carosio, Federico; Camino, Giovanni; Antonietti, Markus; Bergström, Lennart

    2015-03-01

    High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m-1 K-1, which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials.

  16. Interplay of Interfacial Layers and Blend Composition To Reduce Thermal Degradation of Polymer Solar Cells at High Temperature.

    Science.gov (United States)

    Ben Dkhil, Sadok; Pfannmöller, Martin; Schröder, Rasmus R; Alkarsifi, Riva; Gaceur, Meriem; Köntges, Wolfgang; Heidari, Hamed; Bals, Sara; Margeat, Olivier; Ackermann, Jörg; Videlot-Ackermann, Christine

    2018-01-31

    The thermal stability of printed polymer solar cells at elevated temperatures needs to be improved to achieve high-throughput fabrication including annealing steps as well as long-term stability. During device processing, thermal annealing impacts both the organic photoactive layer, and the two interfacial layers make detailed studies of degradation mechanism delicate. A recently identified thermally stable poly[[4,8-bis[(2-ethylhexyl)oxy]benzo[1,2-b:4,5-b']dithiophene-2,6-diyl][3-fluoro-2-[(2-ethylhexyl)carbonyl]thieno[3,4-b]thiophenediyl

  17. Complex evaluation of properties for some thermal insulating materials of NPP

    International Nuclear Information System (INIS)

    Yurchenko, V.G.; Nazarova, G.A.; Yakunichev, V.N.; Potulov, V.V.; Kazakova, K.A.

    1991-01-01

    The effects of the main operational factors (temperature, ionizing radiation, increased humidity) on some most widely applied fibrous materials are investigated. The samples were irradiated by 60 Co gamma photons at the PKhM-gamma-20 device in air at temperature of 40±1 deg C in order to analyze the radiation resistance of thermal insulating materials. The analysis and generalization of the results of laboratory tests give an opportunity to make the following conclusions. The thermal insulation articles and constructions made of superfine basalt fiber may be used in the zones of rigorous regime. The superfine glass fibers (GF) are recommended to be used for equipment and pipeline shielding in the zones of rigorous control only as a part of multilayer insulation as the second or next layers and only in places where leaks are impossible

  18. Ghosts of thermal past: reef fish exposed to historic high temperatures have heightened stress response to further stressors

    Science.gov (United States)

    Mills, S. C.; Beldade, R.; Chabanet, P.; Bigot, L.; O'Donnell, J. L.; Bernardi, G.

    2015-12-01

    Individual exposure to stressors can induce changes in physiological stress responses through modulation of the hypothalamic-pituitary-interrenal (HPI) axis. Despite theoretical predictions, little is known about how individuals will respond to unpredictable short-lived stressors, such as thermal events. We examine the primary neuroendocrine response of coral reef fish populations from the Îles Eparses rarely exposed to anthropogenic stress, but that experienced different thermal histories. Skunk anemonefish, Amphiprion akallopisos, showed different cortisol responses to a generic stressor between islands, but not along a latitudinal gradient. Those populations previously exposed to higher maximum temperatures showed greater responses of their HPI axis. Archive data reveal thermal stressor events occur every 1.92-6 yr, suggesting that modifications to the HPI axis could be adaptive. Our results highlight the potential for adaptation of the HPI axis in coral reef fish in response to a climate-induced thermal stressor.

  19. A Literature Review of Sealed and Insulated Attics—Thermal, Moisture and Energy Performance

    Energy Technology Data Exchange (ETDEWEB)

    Less, Brennan [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Walker, Iain [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States); Levinson, Ronnen [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2016-08-01

    In this literature review and analysis, we focus on the thermal, moisture and energy performance of sealed and insulated attics in California climates. Thermal. Sealed and insulated attics are expected to maintain attic air temperatures that are similar to those in the house within +/- 10°F. Thermal stress on the assembly, namely high shingle and sheathing temperatures, are of minimal concern. In the past, many sealed and insulated attics were constructed with insufficient insulation levels (~R-20) and with too much air leakage to outside, leading to poor thermal performance. To ensure high performance, sealed and insulated attics in new California homes should be insulated at levels at least equivalent to the flat ceiling requirements in the code, and attic envelopes and ducts should be airtight. We expect that duct systems in well-constructed sealed and insulated attics should have less than 2% HVAC system leakage to outside. Moisture. Moisture risk in sealed and insulated California attics will increase with colder climate regions and more humid outside air in marine zones. Risk is considered low in the hot-dry, highly populated regions of the state, where most new home construction occurs. Indoor humidity levels should be controlled by following code requirements for continuous whole-house ventilation and local exhaust. Pending development of further guidance, we recommend that the air impermeable insulation requirements of the International Residential Code (2012) be used, as they vary with IECC climate region and roof finish. Energy. Sealed and insulated attics provide energy benefits only if HVAC equipment is located in the attic volume, and the benefits depend strongly on the insulation and airtightness of the attic and ducts. Existing homes with leaky, uninsulated ducts in the attic should have major savings. When compared with modern, airtight duct systems in a vented attic, sealed and insulated attics in California may still provide substantial benefit

  20. Numerical study of finned heat pipe-assisted thermal energy storage system with high temperature phase change material

    International Nuclear Information System (INIS)

    Tiari, Saeed; Qiu, Songgang; Mahdavi, Mahboobe

    2015-01-01

    Highlights: • A finned heat pipe-assisted latent heat thermal energy storage system is studied. • The effects of heat pipes spacing and fins geometrical features are investigated. • Smaller heat pipes spacing and longer fins improve the melting rate. • The optimal heat pipe and fin arrangements are determined. - Abstract: In the present study, the thermal characteristics of a finned heat pipe-assisted latent heat thermal energy storage system are investigated numerically. A transient two-dimensional finite volume based model employing enthalpy-porosity technique is implemented to analyze the performance of a thermal energy storage unit with square container and high melting temperature phase change material. The effects of heat pipe spacing, fin length and numbers and the influence of natural convection on the thermal response of the thermal energy storage unit have been studied. The obtained results reveal that the natural convection has considerable effect on the melting process of the phase change material. Increasing the number of heat pipes (decreasing the heat pipe spacing) leads to the increase of melting rate and the decrease of base wall temperature. Also, the increase of fin length results in the decrease of temperature difference within the phase change material in the container, providing more uniform temperature distribution. It was also shown that number of the fins does not have a significant effect on the performance of the system

  1. Thermal Jacket Design Using Cellulose Aerogels for Heat Insulation Application of Water Bottles

    Directory of Open Access Journals (Sweden)

    Hai M. Duong

    2017-11-01

    Full Text Available Thermal jacket design using eco-friendly cellulose fibers from recycled paper waste is developed in this report. Neoprene as an outmost layer, cellulose aerogels in the middle and Nylon as an innermost layer can form the best sandwiched laminate using the zigzag stitching method for thermal jacket development. The temperature of the ice slurry inside the water bottle covered with the designed thermal jackets remains at 0.1 °C even after 4 h, which is the average duration of an outfield exercise. Interestingly, the insulation performance of the designed thermal jackets is much better than the commercial insulated water bottles like FLOE bottles and is very competition to that of vacuum flasks for a same period of 4 h and ambient conditions.

  2. Bimetallic low thermal-expansion panels of Co-base and silicide-coated Nb-base alloys for high-temperature structural applications

    International Nuclear Information System (INIS)

    Rhein, R.K.; Novak, M.D.; Levi, C.G.; Pollock, T.M.

    2011-01-01

    Research highlights: → Low net thermal expansion bimetallic structural lattice constructed. → Temperatures on the order of 1000 deg. C reached. → Improved silicide coating for niobium alloy developed. - Abstract: The fabrication and high temperature performance of low thermal expansion bimetallic lattices composed of Co-base and Nb-base alloys have been investigated. A 2D sheet lattice with a coefficient of thermal expansion (CTE) lower than the constituent materials of construction was designed for thermal cycling to 1000 deg. C with the use of elastic-plastic finite element analyses. The low CTE lattice consisted of a continuous network of the Nb-base alloy C-103 with inserts of high CTE Co-base alloy Haynes 188. A new coating approach wherein submicron alumina particles were incorporated into (Nb, Cr, Fe) silicide coatings was employed for oxidation protection of the Nb-base alloy. Thermal gravimetric analysis results indicate that the addition of submicron alumina particles reduced the oxidative mass gain by a factor of four during thermal cycling, increasing lifetime. Bimetallic cells with net expansion of 6 x 10 -6 /deg. C and 1 x 10 -6 /deg. C at 1000 deg. C were demonstrated and their measured thermal expansion characteristics were consistent with analytical models and finite element analysis predictions.

  3. From a Single-Band Metal to a High-Temperature Superconductor via Two Thermal Phase Transitions

    Energy Technology Data Exchange (ETDEWEB)

    He, R.-H.; Hashimoto, M.; Karapetyan, H.; Koralek, J.D.; Hinton, J.P.; Testaud, J.P.; Nathan, V.; Yoshida, Y.; Yao, H.; Tanaka, K.; Meevasana, W.; Moore, R.G.; Lu, D.H.; Mo, S.-K.; Ishikado, M.; Eisaki, H.; Hussain, Z.; Devereaux, T.P.; Kivelson, S.A.; Orenstein, J.; Kapitulnik, A.

    2011-11-08

    The nature of the pseudogap phase of cuprate high-temperature superconductors is one of the most important unsolved problems in condensed matter physics. We studied the commencement of the pseudogap state at temperature T* using three different techniques (angle-resolved photoemission spectroscopy, polar Kerr effect, and time-resolved reflectivity) on the same optimally-doped Bi2201 crystals. We observe the coincident onset at T* of a particle-hole asymmetric antinodal gap, a non-zero Kerr rotation, and a change in the relaxational dynamics, consistent with a phase transition. Upon further cooling, spectroscopic signatures of superconductivity begin to grow close to the superconducting transition temperature (T{sub c}), entangled in an energy-momentum dependent fashion with the pre-existing pseudogap features.

  4. Basalt fiber insulating material with a mineral binding agent for industrial use

    Science.gov (United States)

    Drozdyuk, T.; Aizenshtadt, A.; Tutygin, A.; Frolova, M.

    2016-04-01

    The paper considers a possibility of using mining industry waste as a binding agent for heat insulating material on the basis of basalt fiber. The main objective of the research is to produce a heat-insulating material to be applied in machine building in high-temperature environments. After synthetic binder having been replaced by a mineral one, an environmentally sound thermal insulating material having desirable heat-protecting ability and not failing when exposed to high temperatures was obtained.

  5. Novel load responsive multilayer insulation with high in-atmosphere and on-orbit thermal performance

    Science.gov (United States)

    Dye, S.; Kopelove, A.; Mills, G. L.

    2012-04-01

    Aerospace cryogenic systems require lightweight, high performance thermal insulation to preserve cryopropellants both pre-launch and on-orbit. Current technologies have difficulty meeting all requirements, and advances in insulation would benefit cryogenic upper stage launch vehicles, LH2 fueled aircraft and ground vehicles, and provide capabilities for sub-cooled cryogens for space-borne instruments and orbital fuel depots. This paper reports the further development of load responsive multilayer insulation (LRMLI) that has a lightweight integrated vacuum shell and provides high thermal performance both in-air and on-orbit. LRMLI is being developed by Quest Product Development and Ball Aerospace under NASA contract, with prototypes designed, built, installed and successfully tested. A 3-layer LRMLI blanket (0.63 cm thick, 77 K cold, 295 K hot) had a measured heat leak of 6.6 W/m2 in vacuum and 40.6 W/m2 in air at one atmosphere. In-air LRMLI has an 18× advantage over Spray On Foam Insulation (SOFI) in heat leak per thickness and a 16× advantage over aerogel. On-orbit LRMLI has a 78× lower heat leak than SOFI per thickness and 6× lower heat leak than aerogel. The Phase II development of LRMLI is reported with a modular, flexible, thin vacuum shell and improved on-orbit performance. Structural and thermal analysis and testing results are presented. LRMLI mass and thermal performance is compared to SOFI, aerogel and MLI over SOFI.

  6. Numerical Simulation of Natural Convection in a Vertically Installed Wet Thermal Insulator

    Energy Technology Data Exchange (ETDEWEB)

    Bae, Youngmin; Kim, Seong H.; Seo, Jae K.; Kim, Young I. [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    Natural convection in an enclosure with disconnected vertical partitions inside is thought of as major concerns in the design of thermal insulators. For example, in a system-integrated modular advanced reactor (SMART), vertical partitions are disposed inside the so-called wet thermal insulator with gaps at the top and bottom ends to compensate for thermal expansion . In such a case, buoyancy driven flow circulates throughout the enclosure, i.e., fluid rises up in the hot-side layers, passing through the gap at the top, moving downward in the vertical channels near the cold side, and returning to the hot-side layers via the gap at the bottom. Compared with the case of connected partitions, this often causes an undesirable increase in the circulation flow rate and heat transfer within the enclosure, thus deteriorating the thermal insulation performance. In this study, laminar natural convection in a tall rectangular enclosure with disconnected vertical partitions inside is investigated numerically. The effects of main governing parameters such as the modified Rayleigh number, enclosure height to width ratio, and number of fluid layers are scrutinized along with a discussion of the heat transfer regimes. This study investigates the laminar natural convection in a tall rectangular enclosure having isothermal side walls of different temperatures and insulated top and bottom walls with disconnected vertical partitions inside.

  7. Numerical Simulation of Natural Convection in a Vertically Installed Wet Thermal Insulator

    International Nuclear Information System (INIS)

    Bae, Youngmin; Kim, Seong H.; Seo, Jae K.; Kim, Young I.

    2016-01-01

    Natural convection in an enclosure with disconnected vertical partitions inside is thought of as major concerns in the design of thermal insulators. For example, in a system-integrated modular advanced reactor (SMART), vertical partitions are disposed inside the so-called wet thermal insulator with gaps at the top and bottom ends to compensate for thermal expansion . In such a case, buoyancy driven flow circulates throughout the enclosure, i.e., fluid rises up in the hot-side layers, passing through the gap at the top, moving downward in the vertical channels near the cold side, and returning to the hot-side layers via the gap at the bottom. Compared with the case of connected partitions, this often causes an undesirable increase in the circulation flow rate and heat transfer within the enclosure, thus deteriorating the thermal insulation performance. In this study, laminar natural convection in a tall rectangular enclosure with disconnected vertical partitions inside is investigated numerically. The effects of main governing parameters such as the modified Rayleigh number, enclosure height to width ratio, and number of fluid layers are scrutinized along with a discussion of the heat transfer regimes. This study investigates the laminar natural convection in a tall rectangular enclosure having isothermal side walls of different temperatures and insulated top and bottom walls with disconnected vertical partitions inside

  8. Use of XPS thermal insulator boards in design of educational spaces

    African Journals Online (AJOL)

    Heating and cooling equipment capacity becomes smaller than half after proper implementation of thermal insulation. As air conditioning equipment becomes small, implementation of optimization not only becomes free but also reduces the overall cost of construction. Keywords: School, modern materials, Building and ...

  9. Determination of physical properties of fibrous thermal insulation

    Directory of Open Access Journals (Sweden)

    Jeandel G.

    2012-10-01

    Full Text Available The objective of this study is to characterize both experimentally and theoretically, conductive and radiative heat transfer within polyester batting. This material is derived from recycled bottles (PET with fibres of constant diameters. Two other mineral and plant fibrous insulation materials, (glass wool and hemp wool are also characterized for comparative purposes. To determine the overall thermophysical properties of the tested materials, heat flux measurement are carried out using a device developed in house. The radiative properties of the material are determined by an inverse method based on measurements of transmittance and reflectance using a FTIR spectrometer and by solving the equation of radiative heat transfer. These measures are compared to results of numerical simulations.

  10. Thermal Simulation of Switching Pulses in an Insulated Gate Bipolar Transistor (IGBT) Power Module

    Science.gov (United States)

    2015-02-01

    executed with SolidWorks Flow Simulation , a computational fluid-dynamics code. The graph in Fig. 2 shows the timing and amplitudes of power pulses...defined a convective flow of air perpendicular to the bottom surface of the mounting plate, with a velocity of 10 ft/s. The thermal simulations were...Thermal Simulation of Switching Pulses in an Insulated Gate Bipolar Transistor (IGBT) Power Module by Gregory K Ovrebo ARL-TR-7210

  11. Minimization of thermal insulation thickness taking into account condensation on external walls

    OpenAIRE

    Nurettin Yamankaradeniz

    2015-01-01

    Condensation occurs in the inner layers of construction materials at whatever point the partial pressure of water vapor diffuses and reaches its saturation pressure. Condensation, also called sweating, damages materials, reduces thermal resistance, and by increasing the total heat transfer coefficient, results in unwanted events such as increased heat loss. This study applied minimization of thermal insulation thickness with consideration given to condensation in the external walls. The calcu...

  12. Thermal and Energy Performance of Conditioned Building Due To Insulated Sloped Roof

    Science.gov (United States)

    Irwan, Suhandi Syiful; Ahmed, Azni Zain; Zakaria, Nor Zaini; Ibrahim, Norhati

    2010-07-01

    For low-rise buildings in equatorial region, the roof is exposed to solar radiation longer than other parts of the envelope. Roofs are to be designed to reject heat and moderate the thermal impact. These are determined by the design and construction of the roofing system. The pitch of roof and the properties of construction affect the heat gain into the attic and subsequently the indoor temperature of the living spaces underneath. This finally influences the thermal comfort conditions of naturally ventilated buildings and cooling load of conditioned buildings. This study investigated the effect of insulated sloping roof on thermal energy performance of the building. A whole-building thermal energy computer simulation tool, Integrated Environmental Solution (IES), was used for the modelling and analyses. A building model with dimension of 4.0 m × 4.0 m × 3.0 m was designed with insulated roof and conventional construction for other parts of the envelope. A 75 mm conductive insulation material with thermal conductivity (k-value) of 0.034 Wm-1K-1 was installed underneath the roof tiles. The building was modelled with roof pitch angles of 0° , 15°, 30°, 45°, 60° and simulated for the month of August in Malaysian climate conditions. The profile for attic temperature, indoor temperature and cooling load were downloaded and evaluated. The optimum roof pitch angle for best thermal performance and energy saving was identified. The results show the pitch angle of 0° is able to mitigate the thermal impact to provide the best thermal condition with optimum energy savings. The maximum temperature difference between insulated and non-insulted roof for attic (AtticA-B) and indoor condition (IndoorA-B) is +7.8 °C and 0.4 °C respectively with an average energy monthly savings of 3.9 %.

  13. Discharging process of a finned heat pipe–assisted thermal energy storage system with high temperature phase change material

    International Nuclear Information System (INIS)

    Tiari, Saeed; Qiu, Songgang; Mahdavi, Mahboobe

    2016-01-01

    Highlights: • The discharging process of a latent heat thermal energy storage system is studied. • The thermal energy storage system is assisted by finned heat pipes. • The influences of heat pipe spacing and fins geometrical features are studied. • Smaller heat pipe spacing enhances the solidification rate. • Better heat pipe and fin arrangements are determined. - Abstract: This paper presents the results of a numerical study conducted to investigate the discharging process of a latent heat thermal energy storage system assisted by finned heat pipes. A two-dimensional finite volume based numerical model along with enthalpy-porosity technique is employed to simulate the phase change of storage media during the discharging mode. The thermal energy storage system in this study consists of a square container, finned heat pipes, and potassium nitrate (KNO 3 ) as the phase change material. The charging process of the same thermal energy storage system was reported in an early paper by the authors. This paper reports the results of discharging process of the thermal energy storage system. The influences of heat pipe spacing, fin geometry and quantities as well as the effects of natural convection heat transfer on the thermal performance of the storage system were studied. The results indicate that the phase change material solidification process is hardly affected by the natural convection. Decreasing the heat pipe spacing results in faster discharging process and higher container base wall temperature. Increasing the fins length does not change the discharging time but yields higher base wall temperature. Using more fins also accelerates the discharging process and increases the container base wall temperature.

  14. Thermal expansion and density measurements of molten and solid materials at high temperatures by the gamma attenuation technique

    International Nuclear Information System (INIS)

    Drotning, W.D.

    1979-05-01

    An apparatus is described for the measurement of the density and thermal expansion of molten materials to 3200 0 K using the gamma attenuation technique. The precision of the experimental technique was analytically examined for both absolute and relative density determinations. Three analytical expressions used to reduce data for liquid density determinations were evaluated for their precision. Each allows use of a different set of input data parameters, which can be chosen based on experimental considerations. Using experimentally reasonable values for the precision of the parameters yields a similar resultant density precision from the three methods, on the order of 0.2%. The analytical method for measurements of the linear thermal expansion of solids by the gamma method is also described. To demonstrate the use of the technique on reasonably well-characterized systems, data are presented for (1) the density and thermal expansion of molten tin, lead, and aluminum to 1300 0 K, (2) the thermal expansion of solid aluminum to the melting point, and (3) the thermal expansion of a low melting point glass through the transition temperature and melting region. The data agree very well with published results using other methods where such published data exist

  15. High temperature oxidation interfacial growth kinetics in YSZ thermal barrier coatings with bond coatings of NiCoCrAlY with 0.25% Hf

    Energy Technology Data Exchange (ETDEWEB)

    Soboyejo, W.O. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Mensah, P., E-mail: mensah@engr.subr.edu [Department of Mechanical Engineering, Southern University and A and M College, Baton Rouge, LA 70813 (United States); Diwan, R. [Department of Mechanical Engineering, Southern University and A and M College, Baton Rouge, LA 70813 (United States); Crowe, J. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544 (United States); Akwaboa, S. [Department of Mechanical Engineering, Southern University and A and M College, Baton Rouge, LA 70813 (United States)

    2011-03-15

    Research highlights: {yields} Isothermal oxidation of standard (STD) and vertically cracked (VC) TBCs has been investigated. {yields} The temporal TGO growth kinetics is parabolic in the temperature range between 900 and 1100 deg. C. {yields} Activation energies correspond to growth kinetics controlled by the diffusion of O{sub 2} in Al{sub 2}O{sub 3}. {yields} Variation in oxidation of TBCs is attributed to its microstructure and in-situ oxygen ingression. {yields} Doping TBC bond coat with Hf appears to have potential for enhancing the development of robust TBCs. - Abstract: The results of an experimental study of the high-temperature isothermal oxidation behavior and microstructural evolution in two variations of air plasma sprayed ceramic thermal barrier coatings (TBCs) are discussed in the paper. Two types of TBC specimens were produced for testing. These include a standard and vertically cracked APS. High temperature oxidation was carried out at 900, 1000, 1100 and 1200 deg. C. The experiments were performed in air under isothermal conditions. At each temperature, the specimens were exposed for 25, 50, 75 and 100 h. The corresponding microstructures and microchemistries of the TBC layers were examined using scanning electron microscopy and energy dispersive X-ray spectroscopy. Changes in the dimensions of the thermally grown oxide layer were determined as functions of time and temperature. The evolution of bond coat microstructures/interdiffusion zones and thermally grown oxide layers were compared in the TBC specimens with standard and vertically cracked microstructures.

  16. Effect of thermal exposure, forming, and welding on high-temperature, dispersion-strengthened aluminum alloy: Al-8Fe-1V-2Si

    Science.gov (United States)

    Kennedy, J. R.; Gilman, P. S.; Zedalis, M. S.; Skinner, D. J.; Peltier, J. M.

    1991-01-01

    The feasibility of applying conventional hot forming and welding methods to high temperature aluminum alloy, Al-8Fe-1V-2Si (FVS812), for structural applications and the effect of thermal exposure on mechanical properties were determined. FVS812 (AA8009) sheet exhibited good hot forming and resistance welding characteristics. It was brake formed to 90 deg bends (0.5T bend radius) at temperatures greater than or equal to 390 C (730 F), indicating the feasibility of fabricating basic shapes, such as angles and zees. Hot forming of simple contoured-flanged parts was demonstrated. Resistance spot welds with good static and fatigue strength at room and elevated temperatures were readily produced. Extended vacuum degassing during billet fabrication reduced porosity in fusion and resistance welds. However, electron beam welding was not possible because of extreme degassing during welding, and gas-tungsten-arc welds were not acceptable because of severely degraded mechanical properties. The FVS812 alloy exhibited excellent high temperature strength stability after thermal exposures up to 315 C (600 F) for 1000 h. Extended billet degassing appeared to generally improve tensile ductility, fatigue strength, and notch toughness. But the effects of billet degassing and thermal exposure on properties need to be further clarified. The manufacture of zee-stiffened, riveted, and resistance-spot-welded compression panels was demonstrated.

  17. High temperature oxidation behavior of hafnium modified NiAl bond coat in EB-PVD thermal barrier coating system

    Energy Technology Data Exchange (ETDEWEB)

    Guo Hongbo; Sun Lidong; Li Hefei [Department of Material Science and Engineering, Beijing University of Aeronautics and Astronautics, No.37 Xueyuan Road, Beijing 100083 (China); Gong Shengkai [Department of Material Science and Engineering, Beijing University of Aeronautics and Astronautics, No.37 Xueyuan Road, Beijing 100083 (China)], E-mail: gongsk@buaa.edu.cn

    2008-06-30

    NiAl coatings doped with 0.5 at.% and 1.5 at.% Hf were produced by co-evaporation of NiAl and Hf ingots by electron beam physical vapor deposition (EB-PVD), respectively. The addition of 0.5 at.% Hf significantly improved the cyclic oxidation resistance of the NiAl coating. The TGO layer in the 1.5 at.% Hf doped NiAl coating is straight; while that in the 0.5 at.% Hf doped coating became undulated after thermal cycling. The doped NiAl thermal barrier coatings (TBCs) revealed improved thermal cycling lifetimes at 1423 K, compared to the undoped TBC. Failure of the 0.5 at.% Hf doped TBC occurred by cracking at the interface between YSZ topcoat and bond coat, while the 1.5 at.% Hf doped TBC cracked at the interface between bond coat and substrate.

  18. High temperature study on the thermal properties of few-layer Mo0.5W0.5S2 and effects of capping layers

    Directory of Open Access Journals (Sweden)

    Hong Gu

    Full Text Available We investigated the thermal properties of few-layer Mo0.5W0.5S2 using a series of samples with different kinds of capping layers. Temperature-dependent Raman measurements were conducted in the range of 300–500 K, with power-dependent measurements also carried out. It indicated, for the few-layer Mo0.5W0.5S2, the temperature coefficients of the WS2-like E12g mode, MoS2-like E12g mode and A1g mode were −0.0155 cm−1/K, −0.0146 cm−1/K, and −0.0130 cm−1/K, respectively. And the thermal conductivity was estimated to be 44.8 W/mK. Moreover, the Mo0.5W0.5S2 samples coated with capping layers (ZrO2, HfO2 both showed a better thermal stability and a larger thermal conductivity than the one without. The results revealed that the capping layer should be an important factor in the thermal property. Keywords: Mo0.5W0.5S2, TMDs, Thermal properties, High temperature, Capping layers, Raman

  19. SIMS and thermal evolution analysis of oxygen in Zr-1%Nb alloy after high-temperature transitions

    Czech Academy of Sciences Publication Activity Database

    Lorinčík, Jan; Klouček, V.; Negyesi, M.; Kabátová, J.; Novotný, L.; Vrtílková, V.

    2011-01-01

    Roč. 43, 1-2 (2011), s. 618-620 ISSN 0142-2421 Institutional research plan: CEZ:AV0Z20670512 Keywords : SIMS * Thermal evolution analysis * Zirconium alloy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.180, year: 2011

  20. Tubular House - Form Follows Technology, Concrete Shell Structure with Inner Thermal Insulation

    Science.gov (United States)

    Idem, Robert; Kleczek, Paweł; Pawłowski, Krzysztof; Chudoba, Piotr

    2017-10-01

    The aim of this paper is the theoretical analysis of the possibilities and limitations of using an unconventional technology and the original architectural form stemming from it - the building with external construction and internal insulation. In Central European climatic conditions, the traditional solution for the walls of heated buildings relies on using external thermal insulation. This stems from building physics: it prevents interstitial condensation of water vapour in the wall. Internal insulation is used exceptionally. This is done e.g. in historical buildings undergoing thermal modernization (due to the impossibility of interfering with facade). In such cases, a thermal insulation layer is used on the internal wall surface, along with an additional layer of vapour barrier. The concept of building concerns the intentional usage of an internal insulation. In this case, the construction is a tight external reinforced concrete shell. The architectural form of such building is strongly interrelated with the technology, which was used to build it. The paper presents the essence of this concept in descriptive and drawing form. The basic elements of such building are described (the external construction, the internal insulation and ventilation). As a case study, authors present a project of a residential building along with the description of the applied materials and installation solutions, and the results obtained from thermal, humidity and energetic calculations. The discussion presents the advantages and disadvantages of the proposed concept. The basic advantage of this solution is potentially low building cost. This stems from minimizing the ground works, the simplicity of the joints and the outer finish, as well as from the possibility of prefabrication of the elements. The continuity of the thermal insulation allows to reduce the amount of thermal bridges. The applied technology and form are applicable most of all for small buildings, due to limited

  1. Effect of Nano Al2O3 Doping on Thermal Aging Properties of Oil-Paper Insulation

    Directory of Open Access Journals (Sweden)

    Ningchuan Liang

    2018-05-01

    Full Text Available The thermal aging property of oil-paper insulation is a key factor affecting the service life of transformers. In this study, nano-Al2O3 was added to insulating paper to improve its anti-thermal aging property and delay the aging rate of the insulating oil. The composite paper containing 2% nano-Al2O3 had the highest tensile strength and therefore was selected for the thermal aging test. The composite and normal papers were treated with an accelerated thermal aging experiment at the temperature of 130 °C for 56 days. The variations of the degree of polymerization (DP and tensile strength of the insulating papers with aging time were obtained. The characteristics of the insulating oil, including color, acid content, breakdown voltage, and dielectric loss were analyzed. The results revealed that compared with a plain paper, the composite paper maintained a higher DP, and its tensile strength decreased more slowly during the aging process. The oil-impregnated composite paper presented a lighter-colored oil, less viscosity changes, and a considerably lower quantity of thermal aging products. In addition, nano-Al2O3 can effectively adsorb copper compounds and keep part of the acid products and water away from the thermal aging process. This characteristic restrained the catalysis of copper compounds and H+ in the thermal aging reaction and reduced the thermal aging speed of both the insulating paper and the insulating oil.

  2. Characterization and comparative investigation of thermally insulating layers for the turbine and engine construction

    International Nuclear Information System (INIS)

    Steffens, H.D.; Fischer, U.

    1987-01-01

    The aim of the research project was to subject commercially produced thermal insulation layer systems, the use of which seems promising for engine and turbine construction, to standardized characterisation, testing and comparison. Suitable methods and procedures for this had to be developed, in order to be able to derive instructions for optimisation guidelines for the production of improved thermal insulation systems from the results of investigations. In the context of the research project, a computer-controlled thermal shock test rig was first developed, designed and built. This test rig was designed so that important test conditions, such as the heating and cooling speed could be varied reproducibly over wide ranges. Methods and procedures were worked out, which permit a comparative qualitative and quantitative characterisation of layers of thermal insulation. From metallographic investigations, the layer build-up, layer structure, porosity and crack morphology of the layers in the delivered state and after testing could be assessed and compared. X-ray fine structure investigations gave information on the type and quantity of the phases occurring in the ceramic layers. The results of thermal shock tests which were done at different temperature intervals depending on the substrate, could be correlated with the build-up of layers and supplied information on damage mechanisms and the course of failure. (orig.) With 57 figs., 16 tabs., 89 refs [de

  3. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    Science.gov (United States)

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  4. Transparent thermal insulation for prefabricated school buildings; Einsatz transparenter Waermedaemmung an Schulgebaeuden in praefabrizierter Bauweise

    Energy Technology Data Exchange (ETDEWEB)

    Russ, C. [Fraunhofer-Institut fuer Solare Energiesysteme (ISE), Freiburg im Breisgau (Germany). Gruppe Solares Bauen; Buchmann, R. [Leipzigprojekt GmbH, Leipzig (Germany); Duesterhoeft, A. [Holz- und Leichtmetallbau GmbH, Leipzig (Germany)

    1997-12-31

    The existing schools in the new federal states built from prefabricated elements need to be modernized in order to reduce their energy demand. Fitting some 300 square metres of transparent thermal insulation to the south side of a house front may lead to a cut in its thermal energy demand by 74 per cent. This energy consumption is by 12 kWh per square metre lower than the one obtained with opaque thermal insulation. The results of the first demonstration project are described. (MSK) [Deutsch] Die in den neuen Bundeslaendern vorhandenen Schulen in vorgefertigter Bauweise sind energetisch sanierungsbeduerftig. Werden im Rahmen einer Sanierung ca. 300qm transparente Waermedaemmung an der suedorientierten Fassade eingesetzt, so kann der Heizwaermebedarf um 74% herabgesetzt werden. Das sind 12 kWh/qm weniger als bei dem vergleichsweisen Einsatz einer opaken Waermedaemmung. Im Folgenden werden die Ergebnisse des ersten Demonstrationsprojekts beschrieben.

  5. Light and Strong Hierarchical Porous SiC Foam for Efficient Electromagnetic Interference Shielding and Thermal Insulation at Elevated Temperatures.

    Science.gov (United States)

    Liang, Caiyun; Wang, Zhenfeng; Wu, Lina; Zhang, Xiaochen; Wang, Huan; Wang, Zhijiang

    2017-09-06

    A novel light but strong SiC foam with hierarchical porous architecture was fabricated by using dough as raw material via carbonization followed by carbothermal reduction with silicon source. A significant synergistic effect is achieved by embedding meso- and nanopores in a microsized porous skeleton, which endows the SiC foam with high-performance electromagnetic interference (EMI) shielding, thermal insulation, and mechanical properties. The microsized skeleton withstands high stress. The meso- and nanosized pores enhance multiple reflection of the incident electromagnetic waves and elongate the path of heat transfer. For the hierarchical porous SiC foam with 72.8% porosity, EMI shielding can be higher than 20 dB, and specific EMI effectiveness exceeds 24.8 dB·cm 3 ·g -1 at a frequency of 11 GHz at 25-600 °C, which is 3 times higher than that of dense SiC ceramic. The thermal conductivity reaches as low as 0.02 W·m -1 ·K -1 , which is comparable to that of aerogel. The compressive strength is as high as 9.8 MPa. Given the chemical and high-temperature stability of SiC, the fabricated SiC foam is a promising candidate for modern aircraft and automobile applications.

  6. Evaluation of Effective thermal conductivity models on the prismatic fuel block of a Very High Temperature Reactor by CFD analysis

    International Nuclear Information System (INIS)

    Shin, Dong-Ho; Cho, Hyoung-Kyu; Tak, Nam-Il; Park, Goon-Cherl

    2014-01-01

    Effective thermal conductivity models which can be used to analyze the heat transfer phenomena of a prismatic fuel block were evaluated by CFD analysis. In the accident condition of VHTR when forced convection is lost, the heat flows in radial direction through the hexagonal fuel blocks that contain the large number of coolant holes and fuel compacts. Due to the complex geometry of fuel block and radiation heat transfer; the detail heat transfer computation on the fuel block needs excessive computation resources. Therefore, the detail computation isn’t appropriate for the lumped parameter code. The system code such as GAMMA+ adopts effective thermal conductivity model. Despite the complexity in heat transfer modes, the accurate analysis on the heat transfer in fuel block is necessary since it is directly relevant to the integrity of nuclear fuel embedded in fuel block. To satisfy the accurate analysis of complex heat transfer modes with limited computing sources, the credible effective thermal conductivity (ETC) models in which the effects of all of heat transfer modes are lumped is necessary. In this study, various ETC models were introduced and they are evaluated with CFD calculations. It is estimated that Maxwell-based model was the most pertinent one among the introduced ETC models. (author)

  7. Thermal inactivation of foot-and-mouth disease virus in milk using high-temperature, short-time pasteurization.

    Science.gov (United States)

    Tomasula, P M; Kozempel, M F; Konstance, R P; Gregg, D; Boettcher, S; Baxt, B; Rodriguez, L L

    2007-07-01

    Previous studies of laboratory simulation of high temperature, short time pasteurization (HTST) to eliminate foot-and-mouth disease virus (FMDV) in milk have shown that the virus is not completely inactivated at the legal pasteurization minimum (71.7 degrees C/15 s) but is inactivated in a flow apparatus at 148 degrees C with holding times of 2 to 3 s. It was the intent of this study to determine whether HTST pasteurization conducted in a continuous-flow pasteurizer that simulates commercial operation would enhance FMDV inactivation in milk. Cows were inoculated in the mammary gland with the field strain of FMDV (01/UK). Infected raw whole milk and 2% milk were then pasteurized using an Arm-field pilot-scale, continuous-flow HTST pasteurizer equipped with a plate-and-frame heat exchanger and a holding tube. The milk samples, containing FMDV at levels of up to 10(4) plaque-forming units/mL, were pasteurized at temperatures ranging from 72 to 95 degrees C at holding times of either 18.6 or 36 s. Pasteurization decreased virus infectivity by 4 log10 to undetectable levels in tissue culture. However, residual infectivity was still detectable for selected pasteurized milk samples, as shown by intramuscular and intradermal inoculation of milk into naïve steers. Although HTST pasteurization did not completely inactivate viral infectivity in whole and 2% milk, possibly because a fraction of the virus was protected by the milk fat and the casein proteins, it greatly reduced the risk of natural transmission of FMDV by milk.

  8. Effects of thermal-hydraulic feedback on burnup modeling of the deep burn modular high temperature reactor (DB-MHR)

    International Nuclear Information System (INIS)

    Bei, Yea; Wen, Wua; Di, Yuna; Stubbins, J.F.; Venneri, F.

    2007-01-01

    The Deep-Burn concept investigates the use of commercial high temperature gas-cooled reactors such as modular helium reactors (DB-MHR) to transmute spent fuel from light water reactors (LWRs). An essential feature of this technology is the fabrication of spent fuel into TRISO particles with full transuranic composition to achieve very extensive destruction levels (deep-burn) in a one-pass fuel cycle. Due to the strong temperature influence on the cross sections of transuranics, the coupling between temperature and neutronics is very important to be able to simulate realistic operations of the deep burn reactor. In this study, detailed simulations of the DB-MHR operation are performed with a Monte Carlo code system (MCNP-5 + ORIGEN-2.2 + MONTEBURNS-2 for neutronics calculations), POKE code (General Atomics, for thermohydraulics calculations) and NJOY-99 code (for processing nuclear data libraries), called MHRBURNS. Resulting power densities of fuel blocks (from neutronics calculations) are provided as input to the POKE code, which in turn, calculates new temperature distributions. The temperature distributions obtained from POKE are used to update the MCNP input, and NJOY is called to process new nuclear cross sections based on appropriate temperatures. These steps are repeated to calculate the entire burnup performance of the system. In this preliminary study only the feedback on graphite temperature is taken into account. It is observed that the temperature feedback results show a 200 K higher temperature and thus a slight difference in 237 Np and 239 Pu destruction rates, although the overall burnup rates remain the same

  9. Determination of thermal properties of Cs2Cr2O7(s,l) by high temperature Calvet calorimetry

    International Nuclear Information System (INIS)

    Prasad, R.; Agarwal, R.; Roy, K.N.; Iyer, V.S.; Venugopal, V.; Sood, D.D.

    1989-01-01

    Enthalpy increments have been determined for caesium dichromate in the temperature range 335 to 826 K using a high temperature Calvet micro calorimeter. A solid-solid transition has been observed at (620.5±1.5 K) and the melting temperature was found to be (657.0±1.0) K. The corresponding enthalpy values are 15.6±0.2) kJ/mol and 17.0±0.22) kJ/mol. The results thus obtained are utilised for the evaluation of molar heat capacities, standard entropies and free energy functions for Cs 2 Cr 2 O 7 (s,l). The enthalpy increment values were fitted to a polynomial and can be presented by eqs. (1) to (3), respectivley: (1) (H T 0 -H 0 298.15 )(Cs 2 Cr 2 O 7 ,s) (J/mol)=-6.410x10 4 +1.939x10 2 T(K)+7.441x10 -2 T(K) 2 (335 to 620.5 K), (2) (H T 0 -H 0 298.15 )(Cs 2 Cr 2 O 7 ,s) (J/mol)=1.313x10 6 -4.137x10 3 T(K)+3.517T(K) 2 (620.5 to 656 K), (3) (H T 0 -H 0 298.15 )(Cs 2 Cr 2 O 7 ,l) (J/mol)=-1.218x10 5 +3.890x10 2 T(K) (657 to 826 K). (orig.)

  10. Solvothermal method as a green chemistry solution for micro-encapsulation of phase change materials for high temperature thermal energy storage

    Science.gov (United States)

    Tudor, Albert Ioan; Motoc, Adrian Mihail; Ciobota, Cristina Florentina; Ciobota, Dan. Nastase; Piticescu, Radu Robert; Romero-Sanchez, Maria Dolores

    2018-05-01

    Thermal energy storage systems using phase change materials (PCMs) as latent heat storage are one of the main challenges at European level in improving the performances and efficiency of concentrated solar power energy generation due to their high energy density. PCM with high working temperatures in the temperature range 300-500 °C are required for these purposes. However their use is still limited due to the problems raised by the corrosion of the majority of high temperature PCMs and lower thermal transfer properties. Micro-encapsulation was proposed as one method to overcome these problems. Different micro-encapsulation methods proposed in the literature are presented and discussed. An original process for the micro-encapsulation of potassium nitrate as PCM in inorganic zinc oxide shells based on a solvothermal method followed by spray drying to produce microcapsules with controlled phase composition and distribution is proposed and their transformation temperatures and enthalpies measured by differential scanning calorimetry are presented.

  11. 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.

  12. Role of Oxides and Porosity on High-Temperature Oxidation of Liquid-Fueled HVOF Thermal-Sprayed Ni50Cr Coatings

    Science.gov (United States)

    Song, B.; Bai, M.; Voisey, K. T.; Hussain, T.

    2017-02-01

    High chromium content in Ni50Cr thermally sprayed coatings can generate a dense and protective scale at the surface of coating. Thus, the Ni50Cr coating is widely used in high-temperature oxidation and corrosion applications. A commercially available gas atomized Ni50Cr powder was sprayed onto a power plant steel (ASME P92) using a liquid-fueled high velocity oxy-fuel thermal spray with three processing parameters in this study. Microstructure of as-sprayed coatings was examined using oxygen content analysis, mercury intrusion porosimetry, scanning electron microscope (SEM), energy-dispersive x-ray spectroscopy (EDX) and x-ray diffraction (XRD). Short-term air oxidation tests (4 h) of freestanding coatings (without boiler steel substrate) in a thermogravimetric analyzer at 700 °C were performed to obtain the kinetics of oxidation of the as-sprayed coating. Long-term air oxidation tests (100 h) of the coated substrates were performed at same temperature to obtain the oxidation products for further characterization in detail using SEM/EDX and XRD. In all samples, oxides of various morphologies developed on top of the Ni50Cr coatings. Cr2O3 was the main oxidation product on the surface of all three coatings. The coating with medium porosity and medium oxygen content has the best high-temperature oxidation performance in this study.

  13. High-temperature resistant, thermally sprayed diffusion barrier coatings on CFC lightweight materials; Hochtemperaturbestaendige, thermisch gespritzte Diffusionsbarriereschichten auf CFC-Leichtbauchargiergestellen

    Energy Technology Data Exchange (ETDEWEB)

    Drehmann, Rico; Rupprecht, Christian; Wielage, Bernhard; Lampke, Thomas [Technische Univ. Chemnitz (Germany). Inst. fuer Werkstoffwissenschaft und Werkstofftechnik (IWW); Gilbert, Maria; Uhlig, Volker; Trimis, Dimosthenis [Technische Univ. Bergakademie Freiberg (Germany). Inst. fuer Waermetechnik und Thermodynamik (IWTT); Heuer, Volker [ALD Vacuum Technologies GmbH, Hanau (Germany)

    2013-03-15

    In heat treating processes as well as in high temperature brazing processes, charge carriers enable the positioning and transport of work pieces. Recently, charge carriers consisting of graphite or carbon fibre reinforced carbon (CFC) are used. The main disadvantage of charge carriers based on CFC is the undesirable carburization of the overlying components due to diffusion processes. Under this aspect, thermally sprayed coatings are applied on CFC and tested with respect to their suitability as a high-temperature diffusion barrier. The ceramic powders aluminium oxide, aluminium oxide/chromium oxide, aluminium oxide/titanium oxide and zirconium oxide/yttrium oxide are used as a coating material which is processed by means of the powder flame spraying as well as atmospheric plasma spraying. Molybdenum and silicon carbide are used as an adhesive layer. The coating materials aluminium oxide and aluminium oxide/chromium oxide on siliconized CFC presented excellent results. This supplies a large potential of application for thermally sprayed ceramic coatings on carbon-based lightweight materials.

  14. Physical and thermal waste utilisation in industrial high-temperature processes; Stoffliche und thermische Verwertung von Abfaellen in industriellen Hochtemperaturprozessen. Fachseminar

    Energy Technology Data Exchange (ETDEWEB)

    Leithner, R. [ed.

    1998-09-01

    This year`s DVV Colloquium, the eleventh of its kind, was dedicated to ``Physical and thermal waste utilisation in industrial high-temperature processes``, a topic of growing importance in our time. The three old principles of Disperse, Bury, and Forget having been found inexpedient, there is now a growing interest in the three new principles of Avoid, Reduce, and Utilise. The colloquium saw a scientific discussion on physical and thermal waste utilisation in high-temperature processes. Proposals were made for the solution of specific problems, and the economic implications and impact of these solutions on products and the environment were elucidated. [Deutsch] Das diesjaehrige 11. DVV-Kolloquium mit dem Thema: `Stoffliche und thermische Verwertung von Abfaellen in industriellen Hochtemperaturprozessen`, behandelt einen Themenkomplex, der immer mehr an Bedeutung gewinnt. Nachdem sich die drei alten Prinzipien Verteilen, Vergraben, Vergessen als unzweckmaessig herausgestellt haben, gewinnen die drei neuen Prinzipien Vermeiden, Vermindern, Verwerten immer groessere Bedeutung. Stoffliche und thermische Verwertung in industriellen Hochtemperaturprozessen werden in diesem Kolloquium wissenschaftlich diskutiert und Loesungsvorschlaege und deren wirtschaftliche Implikationen und deren Auswirkungen auf die Produkte und die Umwelt beleuchtet. (orig.)

  15. Transient thermal sensation and comfort resulting from adjustment of clothing insulation

    DEFF Research Database (Denmark)

    Goto, Tomonobu; Toftum, Jørn; Fanger, Povl Ole

    2003-01-01

    This study investigated the transient effects on human thermal responses of clothing adjustments. Two different levels of activity were tested, and the temperature was set to result in a warm or cool thermal sensation at each activity level. The subjects (12 females and 12 males) wore identical...... uniforms and were asked to take off or don a part of the uniform after they had adapted to the experimental conditions for more than 20 minutes. The results showed that the thermal sensation votes responded immediately to the adjustment of clothing insulation and reached a new steady-state level within 5...

  16. Preparation and encapsulation performance of Al_2O_3-SiO_2-B_2O_3 glass-ceramic for high temperature thermal storage

    International Nuclear Information System (INIS)

    Li, Ruguang; Zhu, Jiaoqun; Zhou, Weibing; Cheng, Xiaomin; Liu, Fengli

    2017-01-01

    Highlights: • Al_2O_3-B_2O_3-SiO_2 has good chemical durability, corrosion resistance and dense structure. • The material rarely used in high temperature thermal storage. • The material was prepared and characterized in the paper. - Abstract: In this paper, Al_2O_3-SiO_2-B_2O_3 glass-ceramic was prepared and characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM), further, the porosity was detected by Archimedes principle, thermo physical properties were investigated by differential scanning calorimeter (DSC), respectively. The phase composition was detected by XRD, and the morphology was observed by SEM. The results indicated that the thermal conductivities of the Al_2O_3-SiO_2-B_2O_3 glass-ceramic were between 1.3 and 1.5 W·(m·K)"−"1, and the material had good thermal stability in the range of 300–900 °C. The porosity and apparent density were increased with the temperature. The porosity of Al_2O_3-SiO_2-B_2O_3 glass-ceramic in ranging from 1.2 to 9.6%, the apparent density were between 2.12 and 2.67 g·cm"−"3, and heat capacities were between 0.64 and 0.79 kJ/(kg·K). All the results indicated that the Al_2O_3-SiO_2-B_2O_3 glass-ceramic can be applied as encapsulation material in high temperature latent thermal energy storage.

  17. High temperature materials

    International Nuclear Information System (INIS)

    2003-01-01

    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.)

  18. Pore Scale Thermal Hydraulics Investigations of Molten Salt Cooled Pebble Bed High Temperature Reactor with BCC and FCC Configurations

    Directory of Open Access Journals (Sweden)

    Shixiong Song

    2014-01-01

    CFD results and empirical correlations’ predictions of pressure drop and local Nusselt numbers. Local pebble surface temperature distributions in several default conditions are investigated. Thermal removal capacities of molten salt are confirmed in the case of nominal condition; the pebble surface temperature under the condition of local power distortion shows the tolerance of pebble in extreme neutron dose exposure. The numerical experiments of local pebble insufficient cooling indicate that in the molten salt cooled pebble bed reactor, the pebble surface temperature is not very sensitive to loss of partial coolant. The methods and results of this paper would be useful for optimum designs and safety analysis of molten salt cooled pebble bed reactors.

  19. RESEARCHES REGARDING USE OF TEXTILE MATERIALS FOR THERMAL INSULATION AT NEGATIVE TEMPERATURES

    Directory of Open Access Journals (Sweden)

    IOSUB Andrei

    2014-05-01

    Full Text Available Using thermal insulation in negative temperature acts to reduce heat flow to the cooled space or to objects that have a temperature below ambient temperature. To achieve economic operation of the space to be cooled insulation thickness and quality is an important factor. In this article we want to compare three products used in thermal insulation at negative temperatures: expanded polystyrene, non-woven and wool coats. The materials will be tested with a mechanical vapor compression refrigerator capable of producing temperatures in the range +4 .. -35 ° C, managed by a programmer Dixel capable of recording values between +40. .. -60 °C. Refrigeration insulation enclosure was made with 100 mm expanded polystyrene. On one side of the enclosure will be a cut of 250 * 250 mm, chosen in a central position where the material will be introduced to be tested. The dimensions of the samples are 250 * 250 * 60 mm. To check the insulation properties of materials it will be used a temperature logger capable of recording with two probes temperatures between +125...-40° C. One of the probes will be inserted inside the refrigerator and the second probe will be positioned to the outside of the test material adhered to an aluminum plate, in order to read a average temperature. The difference in thickness of the insulation shall be filled with non-woven material. Hardening the assembly will be made using a 6 mm thick OSB board. The materials will be tested in an identical ambient temperature and humidity.

  20. Bio-susceptibility of materials and thermal insulation systems used for historical buildings

    Science.gov (United States)

    Sterflinger, Katja; Ettenauer, Joerg; Pinar, Guadalupe

    2013-04-01

    In historical buildings of Northern countries high levels of energy are necessary to reach comfortable temperatures especially during the cold season. For this reason historical buildings are now also included in country specific regulations and ordinances to enhance the "energy - efficiency". Since an exterior insulation - as it is commonly used for modern architecture - is incompatible with monument protection, several indoor insulation systems based on historical and ecological materials, are on the market that should improve the thermic performance of a historical building. However, using organic materials as cellulose, loam, weed or wood, bears the risk of fungal growth and thus may lead to health problems in indoor environments. For this reason 5 different ecological indoor insulations systems were tested for their bio-susceptibility against various fungi both under natural conditions - after 2 years of installation in an historical building - and under laboratory conditions with high levels of relative humidity. Fungal growth was evaluated by classical isolation and cultivation as well as by molecular methods. The materials turned out to have a quite different susceptibility towards fungal contamination. Whereas insulations made of bloated Perlite (plaster and board) did not show any fungal growth after 2 years of exposition, the historical insulation made of loam and weed had high cell counts of various fungi. In laboratory experiments wooden softboard represented the best environment for fungal growth. As a result from this study, plaster and board made of bloated Perlite are presented as being the most appropriate materials for thermal insulation at least from the microbiological and hygienic point of view. For future investigations and for the monitoring of fungi in insulation and other building materials we suggest a molecular biology approach with a common protocol for quantitative DNA-extraction and amplification.

  1. Modeling thermal performance of exterior walls retrofitted from insulation and modified laterite based bricks materials

    Science.gov (United States)

    Wati, Elvis; Meukam, Pierre; Damfeu, Jean Claude

    2017-12-01

    Uninsulated concrete block walls commonly found in tropical region have to be retrofitted to save energy. The thickness of insulation layer used can be reduced with the help of modified laterite based bricks layer (with the considerably lower thermal conductivity than that of concrete block layer) during the retrofit building fabrics. The aim of this study is to determine the optimum location and distribution of different materials. The investigation is carried out under steady periodic conditions under the climatic conditions of Garoua in Cameroon using a Simulink model constructed from H-Tools (the library of Simulink models). Results showed that for the continuous air-conditioned space, the best wall configuration from the maximum time lag, minimum decrement factor and peak cooling transmission load perspective, is dividing the insulation layer into two layers and placing one at the exterior surface and the other layer between the two different massive layers with the modified laterite based bricks layer at the interior surface. For intermittent cooling space, the best wall configuration from the minimum energy consumption depends on total insulation thickness. For the total insulation thickness less than 8 cm approximately, the best wall configuration is placing the half layer of insulation material at the interior surface and the other half between the two different massive layers with the modified earthen material at the exterior surface. Results also showed that, the optimum insulation thickness calculated from the yearly cooling transmission (estimated only during the occupied period) and some economic considerations slightly depends on the location of that insulation.

  2. Utilization of Baggase Waste Based Materials as Improvement for Thermal Insulation of Cement Brick

    Directory of Open Access Journals (Sweden)

    Aminudin Eeydzah

    2017-01-01

    Full Text Available Building materials having low thermal load and low thermal conductivity will provide thermal comforts to the occupants in building. In an effort to reduce the use of high energy and waste products from the agricultural industry, sugarcane bagasse and banana bagasse has been utilize as an additive in the manufacture of cement brick. The aim of this study is to investigate the insulation and mechanical properties of brick that has been mixed with bagasse and its effectiveness as thermal insulation using heat flow meter. Waste bagasse is being treated using sodium hydroxide (NaOH and is characterized using SEM and XRF. The samples produced with two different dimensions of 50 mm × 50 mm × 50 mm and 215mm × 102.5mm × 65mm for thermal conductivity test. Next, the sample varies from 0% (control sample, 2%, 4%, 6%, 8% and 10% in order to determine the best mix proportion. The compressive strength is being tested for 7, 14 and 28 days of water curing. Results showed that banana bagasse has lower thermal conductivity compared to sugarcane bagasse used, with compressive strength of 15.6MPa with thermal conductivity 0.6W/m.K.

  3. Experimental Study on Hygrothermal Deformation of External Thermal Insulation Cladding Systems with Glazed Hollow Bead

    Directory of Open Access Journals (Sweden)

    Houren Xiong

    2016-01-01

    Full Text Available This research analyzes the thermal and strain behavior of external thermal insulation cladding systems (ETICS with Glazed Hollow Beads (GHB thermal insulation mortar under hygrothermal cycles weather test in order to measure its durability under extreme weather (i.e., sunlight and rain. Thermometers and strain gauges are placed into different wall layers to gather thermal and strain data and another instrument measures the crack dimensions after every 4 cycles. The results showed that the finishing coat shrank at early stage (elastic deformation and then the finishing coat tends to expand and become damaged at later stage (plastic deformation. The deformation of insulation layer is similar to that of the finishing coat but its variation amplitude is smaller. Deformation of substrate expanded with heat and contracted with cold due to the small temperature variation. The length and width of cracks on the finishing coat grew as the experiment progressed but with a decreasing growth rate and the cracks stopped growing around 70 cycles.

  4. High temperature (>350 °C) thermal histories of the long lived (>500 Ma) active margin of Ecuador and Colombia: Apatite, titanite and rutile U-Pb thermochronology

    Science.gov (United States)

    Paul, Andre N.; Spikings, Richard A.; Ulianov, Alexey; Ovtcharova, Maria

    2018-05-01

    Quantitative reconstruction of thermal histories can be a powerful tool to study numerous natural processes such as tectonic plate interaction, cratonic stability and extra-terrestrial phenomena such as asteroid ejection. A majority of thermochronological studies have focused on temperatures lower than 300 °C. Few previous studies have demonstrated that U-Pb data from apatite and other accessory phases can be used to recover thermal history information at T > 350 °C. We present U-Pb data from apatite, to constrain the thermal histories of Triassic peralluminous anatectites from the Northern Andes between the temperatures of ∼350-550 °C. The accuracy of the thermal history models is assessed by comparisons with previous geological models, and comparisons with pre-existing and newly acquired U/Pb (titanite and rutile), 40Ar/39Ar (muscovite) and low temperature thermochronological data. This study also examines the feasibility of using a large, regionally dispersed apatite U-Pb data set to obtain continuous thermal history paths along a long-lived (>500 Ma) active margin. A second aim of this study is to further test the hypothesis that the dominant mechanism for Pb displacement through apatite is volume diffusion, as opposed to aqueous fluid interaction. The thermal history models derived from the Triassic anatectites exposed in the Andes of Colombia and Ecuador are entirely consistent with lower temperature thermochronological constraints, and previously established geochronological and geochemical constraints. They reveal and quantify trench parallel changes in the amount of Jurassic - Early Cretaceous extension, significantly bolstering and adding to previous tectonic interpretations. Confirmation of the utility of U-Pb thermochronology provides geologists with a powerful tool for investigating the high-temperature thermal evolution of accessory minerals.

  5. Photoacoustic emission from Au nanoparticles arrayed on thermal insulation layer.

    Science.gov (United States)

    Namura, Kyoko; Suzuki, Motofumi; Nakajima, Kaoru; Kimura, Kenji

    2013-04-08

    Efficient photoacoustic emission from Au nanoparticles on a porous SiO(2) layer was investigated experimentally and theoretically. The Au nanoparticle arrays/porous SiO(2)/SiO(2)/Ag mirror sandwiches, namely, local plasmon resonators, were prepared by dynamic oblique deposition (DOD). Photoacoustic measurements were performed on the local plasmon resonators, whose optical absorption was varied from 0.03 (3%) to 0.95 by varying the thickness of the dielectric SiO(2) layer. The sample with high absorption (0.95) emitted a sound that was eight times stronger than that emitted by graphite (0.94) and three times stronger than that emitted by the sample without the porous SiO(2) layer (0.93). The contribution of the porous SiO(2) layer to the efficient photoacoustic emission was analyzed by means of a numerical method based on a one-dimensional heat transfer model. The result suggested that the low thermal conductivity of the underlying porous layer reduces the amount of heat escaping from the substrate and contributes to the efficient photoacoustic emission from Au nanoparticle arrays. Because both the thermal conductivity and the spatial distribution of the heat generation can be controlled by DOD, the local plasmon resonators produced by DOD are suitable for the spatio-temporal modulation of the local temperature.

  6. Thermal response to heat fluxes of the W7-AS divertor surface submitted to surface modification under high temperature treatment

    Energy Technology Data Exchange (ETDEWEB)

    Hildebrandt, D., E-mail: dieter.hildebrandt@ipp.mpg.d [Euratom Association, Max-Planck-Institut fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstrasse 1, 17491 Greifswald (Germany); Duebner, A. [Euratom Association, Max-Planck-Institut fuer Plasmaphysik, Teilinstitut Greifswald, Wendelsteinstrasse 1, 17491 Greifswald (Germany); Greuner, H.; Wiltner, A. [Teilinstitut Garching, Boltzmannstr. 2, 85748 Garching (Germany)

    2009-06-15

    Some target tiles of the W7-AS divertor has been investigated with respect to their thermal behaviour at the surface during power loading with well-defined heat fluxes in the Gladis facility. The primary aim was to examine uncertainties in the determination of heat fluxes derived from IR-thermography during operation of W7-AS. It is found that the derived heat flux profiles are strongly influenced by the local distribution of plasma-deposited contamination analyzed by AES and SIMS. With the observed actual surface conditions characterized by redeposited contamination equivalent up to about 1 mum thickness, the heat fluxes were partially overestimated up to a factor of 4 during operation of W7-AS. This uncertainty is observed to be significantly reduced after heat treatment at temperatures beyond 700 deg. C attained at power flux densities of 10.5 MW/m{sup 2} and durations longer than 5 s.

  7. An Electron Microscope Study of the Thermal Neutron Induced Loss in High Temperature Tensile Ductility of Nb Stabilized Austenitic Steels

    Energy Technology Data Exchange (ETDEWEB)

    Roy, R B

    1965-04-15

    Irradiated {approx}3 x 10{sup 19} n/cm{sup 2} (thermal), <3 x 10{sup 18} n/cm{sup 2} (> 1 MeV) at 40 deg C and the corresponding unirradiated control tensile specimens of a 20 % Cr, 25 % Ni, Nb stabilized steel tested at 650 deg C, 750 deg C and 800 deg C have been examined by transmission electron microscopy. The results indicate that the irradiation induced embrittlement of the tensile specimens at elevated temperatures is preceded by the formation of fine precipitates within the grains. These precipitates may restrict the deformation within the grains such that the stresses are concentrated at the grain boundaries thereby leading to premature failure. It is suggested that the main effect of the irradiation is to promote conditions necessary for the formation of these precipitates, namely, super saturation and fresh nucleation sites within the matrix through the energetic emission of He and Li atoms from boron as an impurity.

  8. Thermal response to heat fluxes of the W7-AS divertor surface submitted to surface modification under high temperature treatment

    International Nuclear Information System (INIS)

    Hildebrandt, D.; Duebner, A.; Greuner, H.; Wiltner, A.

    2009-01-01

    Some target tiles of the W7-AS divertor has been investigated with respect to their thermal behaviour at the surface during power loading with well-defined heat fluxes in the Gladis facility. The primary aim was to examine uncertainties in the determination of heat fluxes derived from IR-thermography during operation of W7-AS. It is found that the derived heat flux profiles are strongly influenced by the local distribution of plasma-deposited contamination analyzed by AES and SIMS. With the observed actual surface conditions characterized by redeposited contamination equivalent up to about 1 μm thickness, the heat fluxes were partially overestimated up to a factor of 4 during operation of W7-AS. This uncertainty is observed to be significantly reduced after heat treatment at temperatures beyond 700 deg. C attained at power flux densities of 10.5 MW/m 2 and durations longer than 5 s.

  9. An Electron Microscope Study of the Thermal Neutron Induced Loss in High Temperature Tensile Ductility of Nb Stabilized Austenitic Steels

    International Nuclear Information System (INIS)

    Roy, R.B.

    1965-04-01

    Irradiated ∼3 x 10 19 n/cm 2 (thermal), 18 n/cm 2 (> 1 MeV) at 40 deg C and the corresponding unirradiated control tensile specimens of a 20 % Cr, 25 % Ni, Nb stabilized steel tested at 650 deg C, 750 deg C and 800 deg C have been examined by transmission electron microscopy. The results indicate that the irradiation induced embrittlement of the tensile specimens at elevated temperatures is preceded by the formation of fine precipitates within the grains. These precipitates may restrict the deformation within the grains such that the stresses are concentrated at the grain boundaries thereby leading to premature failure. It is suggested that the main effect of the irradiation is to promote conditions necessary for the formation of these precipitates, namely, super saturation and fresh nucleation sites within the matrix through the energetic emission of He and Li atoms from boron as an impurity

  10. Thermal Performance Testing of Cryogenic Multilayer Insulation with Silk Net Spacers

    International Nuclear Information System (INIS)

    Johnson, W L; Frank, D J; Nast, T C; Fesmire, J E

    2015-01-01

    Early comprehensive testing of cryogenic multilayer insulation focused on the use of silk netting as a spacer material. Silk netting was used for multiple test campaigns that were designed to provide baseline thermal performance estimates for cryogenic insulation systems. As more focus was put on larger systems, the cost of silk netting became a deterrent and most aerospace insulation firms were using Dacron (or polyester) netting spacers by the early 1970s. In the midst of the switch away from silk netting there was no attempt to understand the difference between silk and polyester netting, though it was widely believed that the silk netting provided slightly better performance. Without any better reference for thermal performance data, the silk netting performance correlations continued to be used. In order to attempt to quantify the difference between the silk netting and polyester netting, a brief test program was developed. The silk netting material was obtained from Lockheed Martin and was tested on the Cryostat-100 instrument in three different configurations, 20 layers with both single and double netting and 10 layers with single netting only. The data show agreement within 15 - 30% with the historical silk netting based correlations and show a substantial performance improvement when compared to previous testing performed using polyester netting and aluminum foil/fiberglass paper multilayer insulation. Additionally, the data further reinforce a recently observed trend that the heat flux is not directly proportional to the number of layers installed on a system. (paper)

  11. 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.

  12. The film thickness dependent thermal stability of Al{sub 2}O{sub 3}:Ag thin films as high-temperature solar selective absorbers

    Energy Technology Data Exchange (ETDEWEB)

    Xiao Xiudi; Xu Gang, E-mail: xiudixiao@163.com; Xiong Bin; Chen Deming; Miao Lei [Chinese Academy of Sciences, Key Laboratory of Renewable Energy and Gas Hydrates, Guangzhou Institute of Energy Conversion (China)

    2012-03-15

    The monolayer Al{sub 2}O{sub 3}:Ag thin films were prepared by magnetron sputtering. The microstructure and optical properties of thin film after annealing at 700 Degree-Sign C in air were characterized by transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and spectrophotometer. It revealed that the particle shape, size, and distribution across the film were greatly changed before and after annealing. The surface plasmon resonance absorption and thermal stability of the film were found to be strongly dependent on the film thickness, which was believed to be associated with the evolution process of particle diffusion, agglomeration, and evaporation during annealing at high temperature. When the film thickness was smaller than 90 nm, the film SPR absorption can be attenuated until extinct with increasing annealing time due to the evaporation of Ag particles. While the film thickness was larger than 120 nm, the absorption can keep constant even after annealing for 64 h due to the agglomeration of Ag particles. On the base of film thickness results, the multilayer Al{sub 2}O{sub 3}:Ag solar selective thin films were prepared and the thermal stability test illustrated that the solar selectivity of multilayer films with absorbing layer thickness larger than 120 nm did not degrade after annealing at 500 Degree-Sign C for 70 h in air. It can be concluded that film thickness is an important factor to control the thermal stability of Al{sub 2}O{sub 3}:Ag thin films as high-temperature solar selective absorbers.

  13. Vacuum insulation - Panel properties and building applications. HiPTI - High Performance Thermal Insulation - IEA/ECBCS Annex 39 - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Erb, M. (ed.)

    2005-12-15

    This paper takes a look at the properties of vacuum insulation panels (VIP) that have already been developed some time ago for use in appliances such as refrigerators and deep-freezers. Their insulation performance is a factor of five to ten times better than that of conventional insulation. The paper discusses the use of such panels in buildings to provide thin, highly-insulating constructions for walls, roofs and floors. The motivation for examining the applicability of high performance thermal insulation in buildings is discussed, including solutions where severe space limitations and other technical and aesthetic considerations exist. The use of nano-structured materials and laminated foils is examined and discussed. The questions arising from the use of such panels in buildings is discussed and the open questions and risks involved are examined. Finally, an outlook on the introduction of VIP technology is presented and quality assurance aspects are examined. This work was done within the framework of the Task 39 'High Performance Thermal Insulation' of the 'Energy Conservation in Buildings and Community Systems ECBCS' programme of the International Energy Agency IEA.

  14. Selenide isotope generator for the Galileo Mission: SIG thermal insulation evaluaion tests

    International Nuclear Information System (INIS)

    1979-06-01

    Since the SIG program required the use of very high performance thermal insulation materials in rather severe thermal and environmental conditions, a thorough screening and testing program was performed. Several types of materials were included in the preliminary survey. Most promising were oxide and carbonaceous fibrous insulations, oxide and carbonaceous foamed materials, and multilayer materials with both powder and cloth spacers. The latter were only viable for the vacuum option. In all, over one hundred materials from more than sixty manufacturers were evaluated from literature and manufacturers' data. The list was pared to eighteen candidates in seven basic types, i.e., fibrous microporous SiO 2 , fibrous SiO 2 /Al 2 O 3 , fibrous ZrO 2 , fibrous carbon, foamed SiO 2 , foamed carbon, and multilayer. Test results are presented

  15. Thermal Transmittance and the Embodied Energy of Timber Frame Lightweight Walls Insulated with Straw and Reed

    Science.gov (United States)

    Miljan, M.; Miljan, J.

    2015-11-01

    Sustainable energy use has become topical in the whole world. Energy gives us comfort we are used to. EU and national regulations determine energy efficiency of the buildings. This is one side of the problem - energy efficiency of houses during exploitation. But the other side is primary energy content of used materials and more rational use of resources during the whole life cycle of a building. The latter value constitutes about 8 - 20% from the whole energy content. Calculations of energy efficiency of materials lead us to energy efficiency of insulation materials and to comparison of natural and industrial materials taking into account their thermal conductivity as well as their primary energy content. Case study of the test house (built in 2012) insulated with straw bales gave the result that thermal transmittance of investigated straw bale walls was according to the minimum energy efficiency requirements set in Estonia U = 0.12 - 0.22 W/m2K (for walls).

  16. Application of Nanotechnology-Based Thermal Insulation Materials in Building Construction

    Directory of Open Access Journals (Sweden)

    Bozsaky David

    2016-03-01

    Full Text Available Nanotechnology-based materials have previously been used by space research, pharmaceuticals and electronics, but in the last decade several nanotechnology-based thermal insulation materials have appeared in building industry. Nowadays they only feature in a narrow range of practice, but they offer many potential applications. These options are unknown to most architects, who may simply be afraid of these materials owing to the incomplete and often contradictory special literature. Therefore, they are distrustful and prefer to apply the usual and conventional technologies. This article is intended to provide basic information about nanotechnology-based thermal insulation materials for designers. It describes their most important material properties, functional principles, applications, and potential usage options in building construction.

  17. Effects of High Temperature and Thermal Cycling on the Performance of Perovskite Solar Cells: Acceleration of Charge Recombination and Deterioration of Charge Extraction

    KAUST Repository

    Sheikh, Arif D.

    2017-09-18

    In this work, we investigated the effects of high operating temperature and thermal cycling on the photovoltaic performance of perovskite solar cells (PSCs) with a typical mesostructured (m)-TiO2-CH3NH3PbI3-xClx-spiro-OMeTAD architecture. After carrying out temperature-dependent grazing incidence wide-angle X-ray scattering (GIWAXS), in-situ X-ray diffraction (XRD) and optical absorption experiments, thermal durability of PSCs was tested by subjecting the devices to repetitive heating to 70 °C and cooling to room temperature (20 °C). An unexpected regenerative effect was observed after the first thermal cycle; the average power conversion efficiency (PCE) increased by approximately 10 % in reference to the as-prepared device. This increase of PCE was attributed to the heating-induced improvement of crystallinity and p-doping in the hole-transporter, Spiro-OMeTAD, which promotes the efficient extraction of photo-generated carriers. However, further thermal cycles produced a detrimental effect on the photovoltaic performance of PSCs with short-circuit current and fill factor degrading faster than the open-circuit voltage. Similarly, the photovoltaic performance of PSCs degraded at high operation temperatures; both short-circuit current and open-circuit voltage decreased with increasing temperature, but the temperature-dependent trend of fill factor was opposite. Our impedance spectroscopy analysis revealed a monotonous increase of charge transfer resistance and a concurrent decrease of charge recombination resistance with increasing temperature, indicating high recombination of charge carriers. Our results revealed that both thermal cycling and high temperatures produce irreversible detrimental effects on the PSC performance due to the deteriorated interfacial photo-carrier extraction. The present findings suggest that development of robust charge transporters and proper interface engineering are critical for the deployment of perovskite photovoltaics in harsh

  18. Rise-to-power test in High Temperature Engineering Test Reactor. Test progress and summary of test results up to 30 MW of reactor thermal power

    International Nuclear Information System (INIS)

    Nakagawa, Shigeaki; Fujimoto, Nozomu; Shimakawa, Satoshi

    2002-08-01

    The High Temperature Engineering Test Reactor (HTTR) is a graphite moderated and gas cooled reactor with the thermal power of 30 MW and the reactor outlet coolant temperature of 850degC/950degC. Rise-to-power test in the HTTR was performed from April 23rd to June 6th in 2000 as phase 1 test up to 10 MW in the rated operation mode, from January 29th to March 1st in 2001 as phase 2 test up to 20 MW in the rated operation mode and from April 14th to June 8th in 2001 as phase 3 test up to 20 MW in the high temperature test the mechanism of the reactor outlet coolant temperature becomes 850degC at 30 MW in the rated operation mode and 950degC in the high temperature test operation mode. Phase 4 rise-to-power test to achieve the thermal reactor power of 30 MW started on October 23rd in 2001. On December 7th in 2001 it was confirmed that the thermal reactor power and the reactor outlet coolant temperature reached to 30 MW and 850degC respectively in the single loaded operation mode in which only the primary pressurized water cooler is operating. Phase 4 test was performed until March 6th in 2002. JAERI (Japan Atomic Energy Research Institute) obtained the certificate of the pre-operation test from MEXT (Ministry of Education Culture Sports Science and Technology) after all the pre-operation tests by MEXT were passed successfully with the reactor transient test at an abnormal event as a final pre-operation test. From the test results of the rise-up-power test up to 30 MW in the rated operation mode, performance of the reactor and cooling system were confirmed, and it was also confirmed that an operation of reactor facility can be performed safely. Some problems to be solved were found through the tests. By solving them, the reactor operation with the reactor outlet coolant temperature of 950degC will be achievable. (author)

  19. Crack initiation and crack growth in high temperature materials under cyclic thermal stresses; Rissinitiierung und Risswachstum in Hochtemperaturwerkstoffen unter zyklisch thermischer Beanspruchung

    Energy Technology Data Exchange (ETDEWEB)

    Gruen, C.

    1996-12-01

    The high temperatures of use in drive units, such as the combustion chamber or the hot gas turbine, for example, usually cause high temperature changes. Great temperature differences occur for short periods in the components, and thermal shock is produced. In this work, theoretical and experimental investigations are introduced on crack initiation and crack growth in high temperature materials under cyclic thermal stresses. The experiments were carried out with the inter-metallic phase Ni{sub 3}Al, the nickel-based alloy Nimonic 80A and the iron-based alloy PM 2000 strengthened by oxide dispersion (ODS). A characteristic crack appearance picture was found for each material, which was examined more closely. The stresses occurring in the sample during one cycle were calculated with the aid of the finite element program ABAQUS, knowing the specific material parameters. Based on the linear-elastic fracture mechanics, stress intensity factors were calculated on the superimposition principle. Using the material data from isothermal crack propagation experiments, the prediction of fatigue crack spread with cyclic thermal stresses is compared with the experimental findings. (orig./AKF) [Deutsch] Die hohen Einsatztemperaturen in Antriebsaggregaten wie z.B. der Brennkammer oder der Heissgasturbine bedingen in der Regel hohe Temperaturwechsel. Dabei treten kurzzeitig grosse Temperaturunterschiede in den Bauteilen auf, ein Thermoschock wird erzeugt. In der vorliegenden Arbeit werden theoretische und experimentelle Untersuchungen zur Rissinitiierung und zum Risswachstum in Hochtemperaturwerkstoffen unter zyklisch thermischer Belastung vorgestellt. Die Experimente wurden mit der intermetallischen Phase Ni{sub 3}Al, der Nickelbasislegierung Nimonic 80A und der oxid-dispersionsverfestigten (ODS) Eisenbasislegierung PM2000 durchgefuehrt. Fuer jeden Werkstoff stellte sich ein charakteristisches Risserscheinungsbild dar, das naeher untersucht wurde. Die in der Probe auftretenden

  20. Evidence for tectonic, lithologic, and thermal controls on fracture system geometries in an andesitic high-temperature geothermal field

    Science.gov (United States)

    Massiot, Cécile; Nicol, Andrew; McNamara, David D.; Townend, John

    2017-08-01

    Analysis of fracture orientation, spacing, and thickness from acoustic borehole televiewer (BHTV) logs and cores in the andesite-hosted Rotokawa geothermal reservoir (New Zealand) highlights potential controls on the geometry of the fracture system. Cluster analysis of fracture orientations indicates four fracture sets. Probability distributions of fracture spacing and thickness measured on BHTV logs are estimated for each fracture set, using maximum likelihood estimations applied to truncated size distributions to account for sampling bias. Fracture spacing is dominantly lognormal, though two subordinate fracture sets have a power law spacing. This difference in spacing distributions may reflect the influence of the andesitic sequence stratification (lognormal) and tectonic faults (power law). Fracture thicknesses of 9-30 mm observed in BHTV logs, and 1-3 mm in cores, are interpreted to follow a power law. Fractures in thin sections (˜5 μm thick) do not fit this power law distribution, which, together with their orientation, reflect a change of controls on fracture thickness from uniform (such as thermal) controls at thin section scale to anisotropic (tectonic) at core and BHTV scales of observation. However, the ˜5% volumetric percentage of fractures within the rock at all three scales suggests a self-similar behavior in 3-D. Power law thickness distributions potentially associated with power law fluid flow rates, and increased connectivity where fracture sets intersect, may cause the large permeability variations that occur at hundred meter scales in the reservoir. The described fracture geometries can be incorporated into fracture and flow models to explore the roles of fracture connectivity, stress, and mineral precipitation/dissolution on permeability in such andesite-hosted geothermal systems.

  1. Potential of Hollow Glass Microsphere as Cement Replacement for Lightweight Foam Concrete on Thermal Insulation Performance

    Directory of Open Access Journals (Sweden)

    Shahidan Shahiron

    2017-01-01

    Full Text Available Global warming can be defined as a gradual increase in the overall temperature of the earth’s atmosphere. A lot of research work has been carried out to reduce that heat inside the residence such as the used of low density products which can reduce the self-weight, foundation size and construction costs. Foamed concrete it possesses high flow ability, low self-weight, minimal consumption of aggregate, controlled low strength and excellent thermal insulation properties. This study investigate the characteristics of lightweight foamed concrete where Portland cement (OPC was replaced by hollow glass microsphere (HGMs at 0%, 3%, 6%, 9% by weight. The density of wet concrete is 1000 kg/m3 were tested with a ratio of 0.55 for all water binder mixture. Lightweight foamed concrete hollow glass microsphere (HGMs produced were cured by air curing and water curing in tank for 7, 14 and 28 days. A total of 52 concrete cubes of size 100mm × 100mm × 100mm and 215mm × 102.5mm × 65mm were produced. Furthermore, Scanning Electron Microscope (SEM and X-ray fluorescence (XRF were carried out to study the chemical composition and physical properties of crystalline materials in hollow glass microspheres. The experiments involved in this study are compression strength, water absorption test, density and thermal insulation test. The results show that the compressive strength of foamed concrete has reached the highest in 3% of hollow glass microsphere with less water absorption and less of thermal insulation. As a conclusion, the quantity of hollow glass microsphere plays an important role in determining the strength and water absorption and also thermal insulation in foamed concrete and 3% hollow glass microspheres as a replacement for Portland cement (OPC showed an optimum value in this study as it presents a significant effect than other percentage.

  2. Improving thermal insulation of TC4 using YSZ-based coating and SiO2 aerogel

    OpenAIRE

    Jin, Lei; Li, Peizhong; Zhou, Haibin; Zhang, Wei; Zhou, Guodong; Wang, Chun

    2015-01-01

    In this paper, air plasmas spray (APS) was used to prepare YSZ and Sc2O3–YSZ (ScYSZ) coating in order to improve the thermal insulation ability of TC4 alloy. SiO2 aerogel was also synthesized and affixed on TC4 titanium alloy to inhabit thermal flow. The microstructures, phase compositions and thermal insulation performance of three coatings were analyzed in detail. The results of thermal diffusivity test by a laser flash method showed that the thermal diffusivities of YSZ, Sc2O3–YSZ and SiO2...

  3. Surface Thermal Insulation and Pipe Cooling of Spillways during Concrete Construction Period

    Directory of Open Access Journals (Sweden)

    Wang Zhenhong

    2014-01-01

    Full Text Available Given that spillways adopt a hydraulic thin concrete plate structure, this structure is difficult to protect from cracks. The mechanism of the cracks in spillways shows that temperature stress is the major reason for cracks. Therefore, an effective way of preventing cracks is a timely and reasonable temperature-control program. Studies show that one effective prevention method is surface thermal insulation combined with internal pipe cooling. The major factors influencing temperature control effects are the time of performing thermal insulation and the ways of internal pipe cooling. To solve this problem, a spillway is taken as an example and a three-dimensional finite element program and pipe cooling calculation method are adopted to conduct simulation calculation and analysis on the temperature fields and stress fields of concretes subject to different temperature-control programs. The temperature-control effects are then compared. Optimization results show that timely and reasonable surface thermal insulation and water-flowing mode can ensure good temperature-control and anticrack effects. The method has reference value for similar projects.

  4. EVALUATION OF THERMAL INSULATION FOR THREE DIFFERENT MATERIALS USED IN CONSTRUCTION AND COMPLETION OF EXTERNAL WALLS

    Directory of Open Access Journals (Sweden)

    Marcio Carlos Navroski

    2010-05-01

    Full Text Available Summers increasingly hot are bringing large thermal problems within homes and businesses, leading to increased demand for installation of air conditioners and the consequent high energy consumption. Constructions with thermal insulation on its external walls thatcould reduce energy use or even supply the use of such equipment. Due to these factors the present study was to evaluate the insulation in three boxes built with different materials, one made of wooden boards with plain walls, and two built with plywood, wall insulation andinterior walls filled with rice husk and Styrofoam®. The boxes were built after placed in drying oven at 40 °C, then noted the temperature inside the same interval every five minutes using a digital thermometer. The box with inner Styrofoam® showed the lowest variation among the three evaluated, followed by the box of rice husk. These two materials also showed good thermal initial, unlike the box built only with wood, which showed a large interiorheating, lay in a drying oven.

  5. Effect of Insulation Thickness on Thermal Stratification in Hot Water Tanks

    Directory of Open Access Journals (Sweden)

    Burak KURŞUN

    2018-03-01

    Full Text Available One of the important factors to be considered in increasing the efficiency of hot water storage tanks used for thermal energy storage is thermal stratification. Reducing the temperature of the water at the base of the tank provides more utilization of the energy of the heat source during the heating of the water and improves the efficiency of the system. In this study, the effect of the insulation thickness on the outer surface of the tank and the ratio of the tank diameter to the height (D/H on the thermal stratification was investigated numerically. Numerical analyzes were carried out for the condition that the insulation thickness was constant and variable in the range of D/H=0,3-1. Water was used as the heat storage fluid and the analysis results were obtained for eight hours cooling period. Numerical results showed that the temperature difference between the bottom and top surfaces of the tank increased between 7-9 ° C for the range of D / H = 0,3-1 with changing the insulation thickness.

  6. Needle-Bonded Electromagnetic Shielding Thermally Insulating Nonwoven Composite Boards: Property Evaluations

    Directory of Open Access Journals (Sweden)

    Jia-Horng Lin

    2016-10-01

    Full Text Available Complicated environmental problems inevitably arise when technology advances. One major environmental problem is the presence of electromagnetic radiation. Long-term exposure to electromagnetic radiation can damage people’s health in many ways. Therefore, this study proposes producing composite boards with electromagnetic shielding effectiveness and thermal insulation by utilizing the structures and properties of materials. Different combinations of flame-retardant polyester fiber (FR fiber, recycled far-infrared polyester fiber (FI fiber, and 4D low-melting-point fibers (LM fiber were made into flame-retardant and thermally insulating matrices. The matrices and carbon fiber (CF woven fabric in a sandwich-structure were needle-punched in order to be tightly compact, and then circularly heat dried in order to have a heat set and reinforced structure. The test results indicate that Polyester (PET/CF composite boards are mechanically strong and have thermal insulation and electromagnetic shielding effectiveness at a frequency between 0.6 MHz and 3 GHz.

  7. Tailoring a High Temperature Corrosion Resistant FeNiCrAl for Oxy-Combustion Application by Thermal Spray Coating and HIP

    Directory of Open Access Journals (Sweden)

    Jarkko Metsäjoki

    2015-10-01

    Full Text Available Oxy-fuel combustion combined with CCS (carbon capture and storage aims to decrease CO2 emissions in energy production using fossil fuels. Oxygen firing changes power plant boiler conditions compared to conventional firing. Higher material temperatures and harsher and more variable environmental conditions cause new degradation processes that are inadequately understood at the moment. In this study, an Fe-Ni-Cr-Al alloy was developed based on thermodynamic simulations. The chosen composition was manufactured as powder by gas atomization. The powder was sieved into two fractions: The finer was used to produce thermal spray coatings by high velocity oxy-fuel (HVOF and the coarser to manufacture bulk specimens by hot isostatic pressing (HIP. The high temperature corrosion properties of the manufactured FeNiCrAl coating and bulk material were tested in laboratory conditions simulating oxy-combustion. The manufacturing methods and the results of high temperature corrosion performance are presented. The corrosion performance of the coating was on average between the bulk steel references Sanicro 25 and TP347HFG.

  8. Transient plane source (tps) sensors for simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and conductors

    Science.gov (United States)

    Maqsood, Asghari; Anis-ur-Rehman, M.

    2013-12-01

    Thermal conductivity and thermal diffusivity are two important physical properties for designing any food engineering processes1. The knowledge of thermal properties of the elements, compounds and different materials in many industrial applications is a requirement for their final functionality. Transient plane source (tps) sensors are reported2 to be useful for the simultaneous measurement of thermal conductivity, thermal diffusivity and volumetric heat capacity of insulators, conductor liquids3 and high-TC superconductors4. The tps-sensor consists of a resistive element in the shape of double spiral made of 10 micrometer thick Ni-foils covered on both sides with 25 micrometer thick Kapton. This sensor acts both as a heat source and a resistance thermometer for recording the time dependent temperature increase. From the knowledge of the temperature co-efficient of the metal spiral, the temperature increase of the sensor can be determined precisely by placing the sensor in between two surfaces of the same material under test. This temperature increase is then related to the thermal conductivity, thermal diffusivity and volumetric heat capacity by simple relations2,5. The tps-sensor has been used to measure thermal conductivities from 0.001 Wm-1K-1to 600 Wm-1K-1 and temperature ranges covered from 77K- 1000K. This talk gives the design, advantages and limitations of the tpl-sensor along with its applications to the measurementof thermal properties in a variety of materials.

  9. Transient plane source (tps) sensors for simultaneous measurements of thermal conductivity and thermal diffusivity of insulators, fluids and conductors

    International Nuclear Information System (INIS)

    Maqsood, Asghari; Anis-ur-Rehman, M

    2013-01-01

    Thermal conductivity and thermal diffusivity are two important physical properties for designing any food engineering processes 1 . The knowledge of thermal properties of the elements, compounds and different materials in many industrial applications is a requirement for their final functionality. Transient plane source (tps) sensors are reported 2 to be useful for the simultaneous measurement of thermal conductivity, thermal diffusivity and volumetric heat capacity of insulators, conductor liquids 3 and high-T C superconductors 4 . The tps-sensor consists of a resistive element in the shape of double spiral made of 10 micrometer thick Ni-foils covered on both sides with 25 micrometer thick Kapton. This sensor acts both as a heat source and a resistance thermometer for recording the time dependent temperature increase. From the knowledge of the temperature co-efficient of the metal spiral, the temperature increase of the sensor can be determined precisely by placing the sensor in between two surfaces of the same material under test. This temperature increase is then related to the thermal conductivity, thermal diffusivity and volumetric heat capacity by simple relations 2,5 . The tps-sensor has been used to measure thermal conductivities from 0.001 Wm −1 K −1 to 600 Wm −1 K −1 and temperature ranges covered from 77K– 1000K. This talk gives the design, advantages and limitations of the tpl-sensor along with its applications to the measurementof thermal properties in a variety of materials

  10. Assessment for the Applicability of Effective Thermal Conductivity Models on the Prismatic Fuel Assembly of Very High Temperature Reactor

    International Nuclear Information System (INIS)

    Shin, Dong-ho; Cho, Hyoung-kyu; Tak, Nam-il; Park, Goon-cherl

    2014-01-01

    A prismatic gas-cooled reactor is promising reactor type in the Nuclear Hydrogen Development and Demonstration (NHDD) project which was launched at KAERI (Korea Atomic Energy Research Institute). One of the most favorable characteristics of a prismatic gas-cooled reactor is its inherent and passive safety. As one of its inherent safety features, the heat flows through the prismatic core radially during the High Pressure Conduction Cooling (HPCC) or Low Pressure Conduction Cooling (LPCC) event and the radial heat transfer cools down the reactor core passively under such conditions. To verify the inherent safety of its design, the GAMMA+ code that is used to analyze VHTR thermo-fluid transients has been developed by KAERI. The code adopts effective thermal conductivity (ETC) model to analyze radial heat transfer in the core as a lumped parameter model. It is because the fuel block has complex geometry with large number of coolant holes and fuel compacts and the detail heat transfer calculations on that geometry needs excessive computation resources. GAMMA+ is adopting the Maxwell-based ETC model, however, there are several ETC models that could be applied to the GAMMA+ code. In this study, several ETC models will be introduced. They will be compared to CFD calculations which have similar condition with the fuel block. And then the most appropriate ETC model will be suggested for calculating the ETC of the fuel block. For the CFD calculation, unit cell tests with simple geometries were conducted. With unit cell test, the applicability of the ETC models were investigated. And proper ETC models were used to calculate the ETC of the fuel block and the results were compared to that of CFD calculation on the fuel block. In this study, the ETC models are introduced and the applicability of the ETC models to VHTR fuel block was investigated. The results of the ETC models were compared to those of CFD calculation. The CFD calculations were conducted for square graphite block

  11. Design Considerations for Thermally Insulating Structural Sandwich Panels for Hypersonic Vehicles

    Science.gov (United States)

    Blosser, Max L.

    2016-01-01

    Simplified thermal/structural sizing equations were derived for the in-plane loading of a thermally insulating structural sandwich panel. Equations were developed for the strain in the inner and outer face sheets of a sandwich subjected to uniaxial mechanical loads and differences in face sheet temperatures. Simple equations describing situations with no viable solution were developed. Key design parameters, material properties, and design principles are identified. A numerical example illustrates using the equations for a preliminary feasibility assessment of various material combinations and an initial sizing for minimum mass of a sandwich panel.

  12. Density, thermal expansion coefficient and viscosity of sodium tetraborate (borax)-UO2 and of sodium metaborate-UO2 solutions at high temperatures

    International Nuclear Information System (INIS)

    Dalle Donne, M.; Dorner, S.; Roth, A.

    1983-01-01

    Measurements have been performed of the density, of the volumetric thermal expansion coefficient and of the viscosity of liquid sodium tetraborate (borax) and of sodium metaborate both pure and with two different amounts of UO 2 dissolved in each. The viscosity measurements have been performed for the solution of sodium tetraborate with UO 2 and CeO 2 , and with CeO 2 only as well. These data are required for the design of core-catchers based on sodium borates. The density measurements have been performed with the buoyancy method in the temperature range from 825 0 C to 1300 0 C, the viscosity measurements in the temperature range 700-1250 0 C with a modified Haake viscosity balance. The balance was previously calibrated at ambient temperature with a standard calibration liquid and at high temperatures, with data for pure borax available from the literature. (orig.)

  13. Green chemistry solutions for sol–gel micro-encapsulation of phase change materials for high-temperature thermal energy storage

    Directory of Open Access Journals (Sweden)

    Romero-Sanchez Maria Dolores

    2018-01-01

    Full Text Available NaNO3 has been selected as phase change material (PCM due to its convenient melting and crystallization temperatures for thermal energy storage (TES in solar plants or recovering of waste heat in industrial processes. However, incorporation of PCMs and NaNO3 in particular requires its protection (i.e. encapsulation into containers or support materials to avoid incompatibility or chemical reaction with the media where incorporated (i.e. corrosion in metal storage tanks. As a novelty, in this study, microencapsulation of an inorganic salt has been carried out also using an inorganic compound (SiO2 instead of the conventional polymeric shells used for organic microencapsulations and not suitable for high temperature applications (i.e. 300–500 °C. Thus, NaNO3 has been microencapsulated by sol–gel technology using SiO2 as shell material. Feasibility of the microparticles synthetized has been demonstrated by different experimental techniques in terms of TES capacity and thermal stability as well as durability through thermal cycles. The effectiveness of microencapsulated NaNO3 as TES material depends on the core:shell ratio used for the synthesis and on the maximum temperature supported by NaNO3 during use.

  14. Non-linear thermal evolution of the crystal structure and phase transitions of LaFeO3 investigated by high temperature X-ray diffraction

    International Nuclear Information System (INIS)

    Selbach, Sverre M.; Tolchard, Julian R.; Fossdal, Anita; Grande, Tor

    2012-01-01

    The crystal structure, anisotropic thermal expansion and structural phase transition of the perovskite LaFeO 3 has been studied by high-temperature X-ray diffraction from room temperature to 1533 K. The structural evolution of the orthorhombic phase with space group Pbnm and the rhombohedral phase with R3 ¯ c structure of LaFeO 3 is reported in terms of lattice parameters, thermal expansion coefficients, atomic positions, octahedral rotations and polyhedral volumes. Non-linear lattice expansion across the antiferromagnetic to paramagnetic transition of LaFeO 3 at T N =735 K was compared to the corresponding behavior of the ferroelectric antiferromagnet BiFeO 3 to gain insight to the magnetoelectric coupling in BiFeO 3 , which is also multiferroic. The first order phase transition of LaFeO 3 from Pbnm to R3 ¯ c was observed at 1228±9 K, and a subsequent transition to Pm3 ¯ m was extrapolated to occur at 2140±30 K. The stability of the Pbnm and R3 ¯ c polymorphs of LaFeO 3 is discussed in terms of the competing enthalpy and entropy of the two crystal polymorphs and the thermal evolution of the polyhedral volume ratio V A /V B . - Graphical abstract: Aniostropic thermal evolution of the lattice parameters and phase transition of LaFeO 3 . Highlights: ► The crystal structure of LaFeO 3 is studied by HTXRD from RT to 1533 K. ► A non-linear expansion across the Néel temperature is observed for LaFeO 3 . ► The ratio V A /V B is used to rationalize the thermal evolution of the structure.

  15. Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

    Energy Technology Data Exchange (ETDEWEB)

    Menges, F.; Spieser, M.; Riel, H.; Gotsmann, B., E-mail: bgo@zurich.ibm.com [IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Dittberner, M. [IBM Research-Zurich, Säumerstrasse 4, CH-8803 Rüschlikon (Switzerland); Photonics Laboratory, ETH Zurich, 8093 Zurich (Switzerland); Novotny, L. [Photonics Laboratory, ETH Zurich, 8093 Zurich (Switzerland); Passarello, D.; Parkin, S. S. P. [IBM Almaden Research Center, 650 Harry Road, San Jose, California 95120 (United States)

    2016-04-25

    The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is expected to exhibit a strong dependence on the state of vanadium dioxide which undergoes a metal-insulator transition near room temperature. We report the measurement of near field thermal transport between a heated silicon oxide micro-sphere and a vanadium dioxide thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm vanadium dioxide thin film varied to be below and above the metal-insulator-transition, and the sphere temperatures were varied in a range between 100 and 200 °C. The measurements were performed using a vacuum-based scanning thermal microscope with a cantilevered resistive thermal sensor. We observe a thermal conductivity per unit area between the sphere and the film with a distance dependence following a power law trend and a conductance contrast larger than 2 for the two different phase states of the film.

  16. 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.

  17. Thermal conductivity of spray-on foam insulations for aerospace applications

    Science.gov (United States)

    Barrios, Matt; Vanderlaan, Mark; Van Sciver, Steven

    2012-06-01

    A guarded-hot-plate apparatus [1] has been developed to measure the thermal conductivity of spray-on foam insulations (SOFI) at temperatures ranging from 30 K to 300 K. The foam tested in the present study is NCFI 24-124, a polyisocyanurate foam used on the External Tanks of the Space Shuttle. The foam was tested first in ambient pressure air, then evacuated and tested once more. These thermal conductivities were compared to the thermal conductivity taken from a sample immediately after being subjected to conditions similar to those experienced by the foam while on the launch pad at Kennedy Space Center. To mimic the conditions experienced on the launch pad, an apparatus was built to enclose one side of the foam sample in a warm, humid environment while the other side of the sample contacts a stainless steel surface held at 77 K. The thermal conductivity data obtained is also compared to data found in the literature.

  18. High-temperature catalytic reforming of n-hexane over supported and core-shell Pt nanoparticle catalysts: role of oxide-metal interface and thermal stability.

    Science.gov (United States)

    An, Kwangjin; Zhang, Qiao; Alayoglu, Selim; Musselwhite, Nathan; Shin, Jae-Youn; Somorjai, Gabor A

    2014-08-13

    Designing catalysts with high thermal stability and resistance to deactivation while simultaneously maintaining their catalytic activity and selectivity is of key importance in high-temperature reforming reactions. We prepared Pt nanoparticle catalysts supported on either mesoporous SiO2 or TiO2. Sandwich-type Pt core@shell catalysts (SiO2@Pt@SiO2 and SiO2@Pt@TiO2) were also synthesized from Pt nanoparticles deposited on SiO2 spheres, which were encapsulated by either mesoporous SiO2 or TiO2 shells. n-Hexane reforming was carried out over these four catalysts at 240-500 °C with a hexane/H2 ratio of 1:5 to investigate thermal stability and the role of the support. For the production of high-octane gasoline, branched C6 isomers are more highly desired than other cyclic, aromatic, and cracking products. Over Pt/TiO2 catalyst, production of 2-methylpentane and 3-methylpentane via isomerization was increased selectively up to 420 °C by charge transfer at Pt-TiO2 interfaces, as compared to Pt/SiO2. When thermal stability was compared between supported catalysts and sandwich-type core@shell catalysts, the Pt/SiO2 catalyst suffered sintering above 400 °C, whereas the SiO2@Pt@SiO2 catalyst preserved the Pt nanoparticle size and shape up to 500 °C. The SiO2@Pt@TiO2 catalyst led to Pt nanoparticle sintering due to incomplete protection of the TiO2 shells during the reaction at 500 °C. Interestingly, over the Pt/TiO2 catalyst, the average size of Pt nanoparticles was maintained even after 500 °C without sintering. In situ ambient pressure X-ray photoelectron spectroscopy demonstrated that the Pt/TiO2 catalyst did not exhibit TiO2 overgrowth on the Pt surface or deactivation by Pt sintering up to 600 °C. The extraordinarily high stability of the Pt/TiO2 catalyst promoted high reaction rates (2.0 μmol · g(-1) · s(-1)), which was 8 times greater than other catalysts and high isomer selectivity (53.0% of C6 isomers at 440 °C). By the strong metal-support interaction

  19. Validation of a CATHENA fuel channel model for the post blowdown analysis of the high temperature thermal-chemical experiment CS28-1, I - Steady state

    International Nuclear Information System (INIS)

    Rhee, Bo Wook; Kim, Hyoung Tae; Park, Joo Hwan

    2008-01-01

    To form a licensing basis for the new methodology of the fuel channel safety analysis code system for CANDU-6, a CATHENA model for the post-blowdown fuel channel analysis for a Large Break LOCA has been developed, and tested for the steady state of a high temperature thermal-chemical experiment CS28-1. As the major concerns of the post-blowdown fuel channel analysis of the current CANDU-6 design are how much of the decay heat can be discharged to the moderator via a radiation and a convective heat transfer at the expected accident conditions, and how much zirconium sheath would be oxidized to generate H 2 at how high a fuel temperature, this study has focused on understanding these phenomena, their interrelations, and a way to maintain a good accuracy in the prediction of the fuel and the pressure tube temperatures without losing the important physics of the involved phenomena throughout the post-blowdown phase of a LBLOCA. For a better prediction, those factors that may significantly contribute to the prediction accuracy of the steady state of the test bundles were sought. The result shows that once the pressure tube temperature is predicted correctly by the CATHENA heat transfer model between the pressure tube and the calandria tube through a gap thermal resistance adjustment, all the remaining temperatures of the inner ring, middle ring and outer ring FES temperatures can be predicted quite satisfactorily, say to within an accuracy range of 20-25 deg. C, which is comparable to the reported accuracy of the temperature measurement, ±2%. Also the analysis shows the choice of the emissivity of the solid structures (typically, 0.80, 0.34, 0.34 for FES, PT, CT), and the thermal resistance across the CO 2 annulus are factors that significantly affect the steady state prediction accuracy. A question on the legitimacy of using 'transparent' assumption for the CO 2 gas annulus for the radiation heat transfer between the pressure tube and the calandria tube in CATHENA

  20. Analysis of the optical and thermal properties of transparent insulating materials containing gas bubbles

    International Nuclear Information System (INIS)

    Cai, Qilin; Ye, Hong; Lin, Qizhao

    2016-01-01

    Highlights: • Transparent insulating medium containing gas bubbles was proposed. • Radiative transfer and thermal conduction models were constructed. • Bulk transmittance increases first and then decreases with the bubble number. • Effective thermal conductivity decreases with increasing filling ratio. • High filling ratio with large bubbles is preferred for good performance. - Abstract: As a medium of low absorption and low thermal conduction, introducing gas bubbles into semitransparent mediums, such as glass and polycarbonate (PC), may simultaneously improve their light transmission and thermal insulation performances. However, gas bubbles can also enhance light scattering, which is in competition with the effect of the absorption decrease. Moreover, the balance between the visible light transmittance and the effective thermal conductivity should also be considered in the material design. Therefore, a radiative transfer model and the Maxwell–Eucken model for such material were employed to analyze the optical and thermal performances, respectively. The results demonstrate that the transmittance increases when the bubble radius (r) increases with a fixed volume fraction of the gas bubbles (f_v) due to the increased scattering intensity. In addition, the effective thermal conductivity always decreases with increasing f_v. Thus, to achieve both good optical and thermal performances, high f_v with large r is preferred. When f_v=0.5, the transmittance can be kept larger than 50% as long as r ≥ 0.7 mm. To elucidate the application performance, the heat transfer of a freezer adopting the glass or PC with gas bubbles as a cover was analyzed and the energy saving can be nearly 10%.

  1. Thermal processing of strained silicon-on-insulator for atomically precise silicon device fabrication

    International Nuclear Information System (INIS)

    Lee, W.C.T.; Bishop, N.; Thompson, D.L.; Xue, K.; Scappucci, G.; Cederberg, J.G.; Gray, J.K.; Han, S.M.; Celler, G.K.; Carroll, M.S.; Simmons, M.Y.

    2013-01-01

    Highlights: ► Strained silicon-on-insulator (sSOI) samples were flash-annealed at high temperature under ultra-high vacuum conditions. ► The extend of surface strain relaxation depends on the annealing temperature with no strain relaxation observed below 1020 °C. ► A 2 × 1 reconstructed surface with low defect density can be achieved. ► The annealed sSOI surface shows enhanced step undulations due to the unique energetics caused by surface strain. - Abstract: We investigate the ability to reconstruct strained silicon-on-insulator (sSOI) substrates in ultra-high vacuum for use in atomic scale device fabrication. Characterisation of the starting sSOI substrate using μRaman shows an average tensile strain of 0.8%, with clear strain modulation in a crosshatch pattern across the surface. The surfaces were heated in ultra-high vacuum from temperatures of 900 °C to 1100 °C and subsequently imaged using scanning tunnelling microscopy (STM). The initial strain modulation on the surface is observed to promote silicon migration and the formation of crosshatched surface features whose height and pitch increases with increasing annealing temperature. STM images reveal alternating narrow straight S A steps and triangular wavy S B steps attributed to the spontaneous faceting of S B and preferential adatom attachment on S B under biaxial tensile strain. Raman spectroscopy shows that despite these high temperature anneals no strain relaxation of the substrate is observed up to temperatures of 1020 °C. Above 1100 °C, strain relaxation is evident but is confined to the surface.

  2. Low-Cost Bio-Based Carbon Fibers for High Temperature Processing

    Energy Technology Data Exchange (ETDEWEB)

    Paul, Ryan Michael [GrafTech International, Brooklyn Heights, OH (United States); Naskar, Amit [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-03

    GrafTech International Holdings Inc. (GTI), under Award No. DE-EE0005779, worked with Oak Ridge National Laboratory (ORNL) under CRADA No. NFE-15-05807 to develop lignin-based carbon fiber (LBCF) technology and to demonstrate LBCF performance in high-temperature products and applications. This work was unique and different from other reported LBCF work in that this study was application-focused and scalability-focused. Accordingly, the executed work was based on meeting criteria based on technology development, cost, and application suitability. High-temperature carbon fiber based insulation is used in energy intensive industries, such as metal heat treating and ceramic and semiconductor material production. Insulation plays a critical role in achieving high thermal and process efficiency, which is directly related to energy usage, cost, and product competitiveness. Current high temperature insulation is made with petroleum based carbon fibers, and one goal of this protect was to develop and demonstrate an alternative lignin (biomass) based carbon fiber that would achieve lower cost, CO2 emissions, and energy consumption and result in insulation that met or exceeded the thermal efficiency of current commercial insulation. In addition, other products were targeted to be evaluated with LBCF. As the project was designed to proceed in stages, the initial focus of this work was to demonstrate lab-scale LBCF from at least 4 different lignin precursor feedstock sources that could meet the estimated production cost of $5.00/pound and have ash level of less than 500 ppm in the carbonized insulation-grade fiber. Accordingly, a preliminary cost model was developed based on publicly available information. The team demonstrated that 4 lignin samples met the cost criteria. In addition, the ash level for the 4 carbonized lignin samples was below 500 ppm. Processing as-received lignin to produce a high purity lignin fiber was a significant accomplishment in that most industrial

  3. Rapid growth of single-layer graphene on the insulating substrates by thermal CVD

    Energy Technology Data Exchange (ETDEWEB)

    Chen, C.Y. [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China); Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Dai, D.; Chen, G.X.; Yu, J.H. [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Nishimura, K. [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Advanced Nano-processing Engineering Lab, Mechanical Systems Engineering, Kogakuin University (Japan); Lin, C.-T. [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Jiang, N., E-mail: jiangnan@nimte.ac.cn [Key Laboratory of Marine Materials and Related Technologies, Zhejiang Key Laboratory of Marine Materials and Protective Technologies, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo 315201 (China); Zhan, Z.L., E-mail: zl_zhan@sohu.com [Faculty of Materials Science and Engineering, Kunming University of Science and Technology, Kunming 650093 (China)

    2015-08-15

    Highlights: • A rapid thermal CVD process has been developed to directly grow graphene on the insulating substrates. • The treating time consumed is ≈25% compared to conventional CVD procedure. • Single-layer and few-layer graphene can be formed on quartz and SiO{sub 2}/Si substrates, respectively. • The formation of thinner graphene at the interface is due to the fast precipitation rate of carbon atoms during cooling. - Abstract: The advance of CVD technique to directly grow graphene on the insulating substrates is particularly significant for further device fabrication. As graphene is catalytically grown on metal foils, the degradation of the sample properties is unavoidable during transfer of graphene on the dielectric layer. Moreover, shortening the treatment time as possible, while achieving single-layer growth of graphene, is worthy to be investigated for promoting the efficiency of mass production. Here we performed a rapid heating/cooling process to grow graphene films directly on the insulating substrates by thermal CVD. The treating time consumed is ≈25% compared to conventional CVD procedure. In addition, we found that high-quality, single-layer graphene can be formed on quartz, but on SiO{sub 2}/Si substrate only few-layer graphene can be obtained. The pronounced substrate effect is attributed to the different dewetting behavior of Ni films on the both substrates at 950 °C.

  4. Comparative Analysis of the Thermal Insulation of Traditional and Newly Designed Protective Clothing for Foundry Workers

    Directory of Open Access Journals (Sweden)

    Iwona Frydrych

    2016-09-01

    Full Text Available An objective of the undertaken research was checking the applicability of aluminized basalt fabrics for the production of clothing for foundry workers. The results of flammability, the resistance to contact, convective and radiation heat, as well as the resistance to big molten metal splashes confirmed the thesis of applicability of the packages with the use of aluminized basalt fabric content for the assumed purpose; therefore, such protective clothing was produced. Thermal comfort of foundry workers is very important and related to many factors, i.e., the structure of the protective clothing package, the number of layers, their thickness, the distance between the body and appropriate underwear. In the paper, a comparison of the results of thermal insulation measurement of two kinds of protective clothing is presented: the traditional one made of aluminized glass fabrics and the new one made of aluminized basalt fabrics. Measurements of clothing thermal insulation were conducted using a thermal manikin dressed in the protective clothing and three kinds of underwear products covering the upper and lower part of the manikin.

  5. Thermal oxidation induced degradation of carbon fiber reinforced composites and carbon nanotube sheet enhanced fiber/matrix interface for high temperature aerospace structural applications

    Science.gov (United States)

    Haque, Mohammad Hamidul

    Recent increase in the use of carbon fiber reinforced polymer matrix composite, especially for high temperature applications in aerospace primary and secondary structures along with wind energy and automotive industries, have generated new challenges to predict its failure mechanisms and service life. This dissertation reports the experimental study of a unidirectional carbon fiber reinforced bismaleimide (BMI) composites (CFRC), an excellent candidate for high temperature aerospace components, undergoing thermal oxidation at 260 °C in air for over 3000 hours. The key focus of the work is to investigate the mechanical properties of the carbon fiber BMI composite subjected to thermal aging in three key aspects - first, studying its bulk flexural properties (in macro scale), second, characterizing the crack propagation along the fiber direction, representing the interfacial bonding strength between fiber and matrix (in micro scale), and third, introducing nano-structured materials to modify the interface (in nano scale) between the carbon fiber and BMI resin and mechanical characterization to study its influence on mitigating the aging effect. Under the first category, weight loss and flexural properties have been monitored as the oxidation propagates through the fiber/matrix interface. Dynamic mechanical analysis and micro-computed tomography analysis have been performed to analyze the aging effects. In the second category, the long-term effects of thermal oxidation on the delamination (between the composite plies) and debonding (between fiber and matrix) type fracture toughness have been characterized by preparing two distinct types of double cantilever beam specimens. Digital image correlation has been used to determine the deformation field and strain distribution around the crack propagation path. Finally the resin system and the fiber/matrix interface have been modified using nanomaterials to mitigate the degradations caused by oxidation. Nanoclay modified

  6. Solvothermal method as a green chemistry solution for micro-encapsulation of phase change materials for high temperature thermal energy storage

    Directory of Open Access Journals (Sweden)

    Tudor Albert Ioan

    2018-01-01

    Full Text Available Thermal energy storage systems using phase change materials (PCMs as latent heat storage are one of the main challenges at European level in improving the performances and efficiency of concentrated solar power energy generation due to their high energy density. PCM with high working temperatures in the temperature range 300–500 °C are required for these purposes. However their use is still limited due to the problems raised by the corrosion of the majority of high temperature PCMs and lower thermal transfer properties. Micro-encapsulation was proposed as one method to overcome these problems. Different micro-encapsulation methods proposed in the literature are presented and discussed. An original process for the micro-encapsulation of potassium nitrate as PCM in inorganic zinc oxide shells based on a solvothermal method followed by spray drying to produce microcapsules with controlled phase composition and distribution is proposed and their transformation temperatures and enthalpies measured by differential scanning calorimetry are presented.

  7. TORT-TD/ATTICA3D: a coupled neutron transport and thermal hydraulics code system for 3-D transient analysis of gas cooled high temperature reactors

    International Nuclear Information System (INIS)

    Lapins, J.; Seubert, A.; Buck, M.; Bader, J.; Laurien, E.

    2011-01-01

    Comprehensive safety studies of high temperature gas cooled reactors (HTR) require full three dimensional coupled treatments of both neutron kinetics and thermal-hydraulics. In a common effort, GRS and IKE developed the coupled code system TORT-TD/ATTICA3D for pebble bed type HTR that connects the 3-D transient discrete-ordinates transport code TORT-TD with the 3-D porous medium thermal-hydraulics code ATTICA3D. In this paper, the physical models and calculation capabilities of TORT-TD and ATTICA3D are presented, focusing on model improvements in ATTICA3D and extensions made in TORT-TD related to HTR application. For first applications, the OECD/NEA/NSC PBMR-400 benchmark has been chosen. Results obtained with TORT-TD/ATTICA3D will be shown for transient exercises, e.g. control rod withdrawal and a control rod ejection. Results are compared to other benchmark participants' solutions with special focus on fuel temperature modelling features of ATTICA3D. The provided “grey-curtain” nuclear cross section libraries have been used. First results on 3-D effects during a control rod withdrawal transient will be presented. (author)

  8. Crystal structure and thermal expansion of the low- and high-temperature forms of Ba MIV(PO 4) 2 compounds ( M=Ti, Zr, Hf and Sn)

    Science.gov (United States)

    Bregiroux, D.; Popa, K.; Jardin, R.; Raison, P. E.; Wallez, G.; Quarton, M.; Brunelli, M.; Ferrero, C.; Caciuffo, R.

    2009-05-01

    The crystal structure of β-BaZr(PO 4) 2, archetype of the high-temperature forms of Ba M(PO 4) 2 phosphates (with M=Ti, Zr, Hf and Sn), has been solved ab initio by Rietveld analysis from synchrotron X-ray powder diffraction data. The phase transition appears as a topotactic modification of the monoclinic (S.G. C2/m) lamellar α-structure into a trigonal one (S.G. P3¯m1) through a simple mechanism involving the unfolding of the [Zr)]n2- layers. The thermal expansion is very anisotropic (e.g., -4.1< α i<34.0×10 -6 K -1 in the case of α-BaZr(PO 4) 2) and quite different in the two forms, as a consequence of symmetry. It stems from a complex combination of several mechanisms, involving bridging oxygen rocking in M-O-P linkages, and "bond thermal expansion".

  9. RANS simulation of the thermal mixing in HTTF LP during normal operation conditions – High Temperature Test Facility at Oregon State University

    International Nuclear Information System (INIS)

    Gradecka, Malwina J.; Woods, Brian

    2014-01-01

    Since High Temperature Gas-cooled Reactors are being considered as the most promising design of upcoming IV Gen reactors, key research areas were identified to address safety aspects of this design. A number of simulations and experiments need to be conducted in this field. In this paper, thermal-hydraulics aspects of coolant flow through Lower Plenum (LP) of HTGR were considered, specifically flow characteristics to identify the risk of temperature stratification in LP and hot spotting on LP floor. Local temperature gradients can cause material degradation. As the power profile is non-uniform across the core, jets of coolant exit the core region at different temperatures and enter the LP impinging on LP floor causing hot spots at LP structure and temperature stratification. To address those issues numerical simulation and an experiment are being developed. The numerical simulation provides coolant flow velocity and temperature fields. The purpose of this study is to investigate the mixing phenomenon in the LP due to risk of the hot streaking and thermal stratification phenomena during normal operation of HTTF. The following aspect are being examined: identification of gas flow behavior in lower plenum of HTTF based on CFD simulations, identification of hot streaking issue in the HTTF lower plenum using CFD tools, and computational investigation of gas mixing efficiency. This paper includes a description of experimental setup of HTTF, guidance for LP CFD modeling, and the results and analysis of CFD simulation. (author)

  10. Lattice Thermal Conductivity of Ultra High Temperature Ceramics (UHTC) ZrB2 and HfB2 from Atomistic Simulations

    Science.gov (United States)

    Lawson, John W.; Daw, Murray S.; Bauschlicher, Charles W.

    2012-01-01

    Ultra high temperature ceramics (UHTC) including ZrB2 and HfB2 have a number of properties that make them attractive for applications in extreme environments. One such property is their high thermal conductivity. Computational modeling of these materials will facilitate understanding of fundamental mechanisms, elucidate structure-property relationships, and ultimately accelerate the materials design cycle. Progress in computational modeling of UHTCs however has been limited in part due to the absence of suitable interatomic potentials. Recently, we developed Tersoff style parameterizations of such potentials for both ZrB2 and HfB2 appropriate for atomistic simulations. As an application, Green-Kubo molecular dynamics simulations were performed to evaluate the lattice thermal conductivity for single crystals of ZrB2 and HfB2. The atomic mass difference in these binary compounds leads to oscillations in the time correlation function of the heat current, in contrast to the more typical monotonic decay seen in monoatomic materials such as Silicon, for example. Results at room temperature and at elevated temperatures will be reported.

  11. A lime based mortar for thermal insulation of medieval church vaults

    DEFF Research Database (Denmark)

    Larsen, P.K.; Hansen, Tessa Kvist

    A new mortar for thermal insulation of medieval church vaults was tested in a full scale experiment in Annisse Church, DK. The mortar consists of perlite, a highly porous aggregate, mixed with slaked lime. These materials are compatible with the fired clay bricks and the lime mortar joints....... The lambda-value of the insulation mortar is 0.08 W/m K or twice the lambda-value for mineral wool. The water vapour permeability is equal to a medieval clay brick, and it has three times higher capacity for liquid water absorption. The mortar was applied to the top side of the vaults in a thickness of 10 cm......, despite a water vapour pressure gradient up to 500 Pa between the nave and attic. There was no reduction in energy consumption the first winter, possibly due to the increased heat loss related to the drying of the mortar....

  12. A system for the thermal insulation of a pre-stressed concrete vessel

    International Nuclear Information System (INIS)

    Aubert, Gilles; Petit, Guy.

    1975-01-01

    This invention concerns the thermal insulation of a pre-stressed concrete vessel for a pressurised water nuclear reactor, this vessel being fitted internally with a leak-proof metal lining. Two rings are placed at the lower and upper parts of the vessel respectively. The upper ring is closed with a cover. These rings differ in diameter, are fitted with a metal insulating and mark the limits of a chamber between the vaporisable fluid and the internal wall of the vessel. This chamber is filled with a fluid in the liquid phase up to the liquid/vapor interface level of the fluid and with a gas above that level, the covering of the rings forming a cold fluid liquid seal. Each ring is supported by the vessel. Leak-proof components take up the radial expansion of the rings [fr

  13. Supersymmetry at high temperatures

    International Nuclear Information System (INIS)

    Das, A.; Kaku, M.

    1978-01-01

    We investigate the properties of Green's functions in a spontaneously broken supersymmetric model at high temperatures. We show that, even at high temperatures, we do not get restoration of supersymmetry, at least in the one-loop approximation

  14. Numerical Calculation of Transient Thermal Characteristics in Gas-Insulated Transmission Lines

    Directory of Open Access Journals (Sweden)

    Hongtao Li

    2013-11-01

    Full Text Available For further knowledge of the thermal characteristics in gas-insulated transmission lines (GILs installed above ground, a finite-element model coupling fluid field and thermal field is established, in which the corresponding assumptions and boundary conditions are given.  Transient temperature rise processes of the GIL under the conditions of variable ambient temperature, wind velocity and solar radiation are respectively investigated. Equivalent surface convective heat transfer coefficient and heat flux boundary conditions are updated in the analysis process. Unlike the traditional finite element methods (FEM, the variability of the thermal properties with temperature is considered. The calculation results are validated by the tests results reported in the literature. The conclusion provides method and theory basis for the knowledge of transient temperature rise characteristics of GILs in open environment.

  15. Feasibility study of thermal insulation materials for core support of experimental VHTR

    International Nuclear Information System (INIS)

    Kawakami, H.; Nakanishi, T.

    1982-01-01

    Thermal insulation materials for core support of the experimental VHTR, planned by JAERI, should maintain moderate compressive strength and dimensional stability as well as low thermal conductivity at the maximum service temperature of 1100 0 C for 20 years. For selecting materials, we investigate properties of some candidates, and evaluate their feasibility. Preliminary tests, heat treatment test and compressive creep tests for 1000 hours at 900 0 C and 1000 0 C were conducted. In the preliminary tests, EG-38B (carbon baked at 1350 0 C) and Fine Finnex 600 (silicon nitride) showed acceptable physical stability. In the heat treatment tests, silicon nitride showed weight loss probably caused by thermal decomposition. Compressive creep deformation of Fine Finnex 600 was negligible under stress of 100 kg/cm 2 for 1000 hours. Heat treatment at 1200 to 1300 0 C for 50 hours improved dimensional stability of carbon at 1000 0 C

  16. Investigation of properties of low-strength lightweight concrete for thermal insulation

    Energy Technology Data Exchange (ETDEWEB)

    UEnal, Osman; Uygunoglu, Tayfun [Construction Department, Technical Education Faculty, Afyon Kocatepe University, 03200 Afyon (Turkey); Yildiz, Ahmet [Afyon Kocatepe University, Engineering Faculty, 03200 Afyon (Turkey)

    2007-02-15

    In this study, block elements with diatomite, which have different aggregate granulometries and cement contents, were produced and the effect of these parameters on physical and mechanical properties of block elements were investigated. Diatomite samples were taken from the region of Afyon. In the mixes, water/cement ratio was kept at 0.15. Analyses include compressive strength, thermal conductivity, ultrasonic velocity tests, bulk density and specific porosity. According to experimental results, while dry unit weight is varied between 900 and 1190kg/m{sup 3}, compressive strength of 7-56 days specimens ranged from 2.5 to 8MPa. Materials with a ratio of 30% fine, 40% medium and 30% coarse size have the best compressive strength and thermal insulation in all series. Due to low thermal conductivity, lightweight aggregate concrete with diatomite can be used to prove high isolation in the structure. (author)

  17. Accelerated thermal and radiation-oxidation combined degradation of electric cable insulation materials

    International Nuclear Information System (INIS)

    Yagi, Toshiaki; Seguchi, Tadao; Yoshida, Kenzo

    1986-03-01

    For the development of accelerated testing methodology to estimate the life time of electric cable, which is installed in radiation field such as a nuclear reactor containment vessel, radiation and thermal combined degradation of cable insulation and jacketing materials was studied. The materials were two types of formulated polyethylene, ethylene-propylene rubber, Hypalon, and Neoprene. With Co-60 γ-rays the materials were irradiated up to 0.5 MGy under vacuum and in oxygen under pressure, then exposed to thermal aging at elevated temperature in oxygen. The degradation was investigated by the tensile test, gelfraction, and swelling measurements. The thermal degradation rate for each sample increases with increase of oxygen concentration, i.e. oxygen pressure, during the aging, and tends to saturate above 0.2 MPa of oxygen pressure. Then, the effects of irradiation and the temperature on the thermal degradation rate were investigated at the oxygen pressure of 0.2 MPa in the temperature range from 110 deg C to 150 deg C. For all of samples irradiated in oxygen, the following thermal degradation rate was accelerated by several times comparing with unirradiated samples, while the rate of thermal degradation for the sample except Neoprene irradiated under vacuum was nearly equal to that of unirradiated one. By the analysis of thermal degradation rate against temperature using Arrhenius equation, it was found that the activation energy tends to decrease for the samples irradiated in oxidation condition. (author)

  18. Computational thermal-fluid dynamics analysis of the laminar flow regime in the meander flow geometry characterizing the heat exchanger used in high temperature superconducting current leads

    International Nuclear Information System (INIS)

    Rizzo, Enrico; Heller, Reinhard; Richard, Laura Savoldi; Zanino, Roberto

    2013-01-01

    Highlights: • The laminar regime in the meander flow geometry has been analysed with a previously validated computation