WorldWideScience

Sample records for material thermal response

  1. Study of improving the thermal response of a construction material containing a phase change material

    Science.gov (United States)

    Laaouatni, A.; Martaj, N.; Bennacer, R.; Elomari, M.; El Ganaoui, M.

    2016-09-01

    The use of phase change materials (PCMs) for improving the thermal comfort in buildings has become an attractive application. This solution contributes to increasing the thermal inertia of the building envelope and reducing power consumption. A building element filled with a PCM and equipped with ventilation tubes is proposed, both for increasing inertia and contributing to refreshing building envelope. A numerical simulation is conducted by the finite element method in COMSOL Multiphysics, which aims to test the thermal behaviour of the developed solution. An experimental study is carried out on a concrete block containing a PCM with ventilation tubes. The objective is to see the effect of PCM coupled with ventilation on increasing the inertia of the block. The results show the ability of this new solution to ensure an important thermal inertia of a building.

  2. IAEA consultants' meeting on thermal response of plasma facing materials and components

    International Nuclear Information System (INIS)

    Janev, R.K.

    1990-07-01

    The present Summary Report contains brief proceedings and the main conclusions and recommendations of the IAEA Consultants' Meeting on ''Thermal Response of Plasma Facing Materials and Components'', which was organized by the IAEA Atomic and Molecular Data Unit and held on June 11-13, 1990, in Vienna, Austria. The Report also includes a categorization and assessment of currently studied plasma facing materials, a classification scheme of material properties data, required in fusion reactor design, and a survey of the urgently needed material properties data. (author)

  3. Thermal management of a multiple mini-channel heat sink by the integration of a thermal responsive shape memory material

    International Nuclear Information System (INIS)

    Di Maio, E.; Mastrullo, R.; Mauro, A.W.; Toto, D.

    2014-01-01

    In this paper, a novel application of a thermo-responsive shape memory polymer (SMP) is proposed to smart-control the forced flow of water in a multi mini-channel heat sink. In particular, it is reported that millimeter-sized cylinders made of SMP could be used to smartly obstruct the fluid flow by adapting the flow cross section to the heat load to be removed. By integrating the sensing, the control and the actuation functions within a unique, millimeter-sized device, these micro-valves, unlike the traditional actuators normally used for flow control, could be easily embedded into small heat sinks, with significant space and energy saving, useful, in particular, in systems where several miniaturized components have to be cooled concurrently, such as the modern mainframes or the concentrated photovoltaic solar cells. Two possible configurations for the SMP were considered in this study: an “open” configuration, without any obstruction of the water flow free and an “obstructed” configuration, with the millimeter-sized cylinder partially occupying the mini-channel. A numerical, steady state analysis was carried out with water in single-phase forced convection, to determine the effect of these two states on the internal fluid flow characteristics under different conditions of heat flux and pressure drop and to evaluate the overall thermal behavior of the smart-controlled multiple mini-channel heat sink in terms of ability to control the temperature of the system and to reduce the energy consumption. -- Highlights: • A novel application of a SMP material is investigated for the thermal management of a heat sink. • Numerical simulations to find the matching of the heat sink and material system after regulation were carried out. • The investigated system is able to control the heat sink temperature. • Further analysis for system stability are required

  4. DETERMINATION OF THERMAL RESPONSE OF CARRARA AND SNEZNIKOVSKY MARBLE USED AS A BUILDING MATERIALS

    Directory of Open Access Journals (Sweden)

    Veronika Petráňová

    2016-02-01

    Full Text Available Physical weathering of marble, widely used as a cladding material on buildings, is one of the most common damaging mechanism caused by anisotropic thermal expansion of calcite grains. The extent of marble deterioration depends mainly on stone fabric and texture. Dry cuboids of Carrara marble and marble from Dolni Morava quarry were subjected to microscopic analysis and thermal cycling, to determine the thermal expansion related to stone fabric and predominant lattice orientation of grains (i.e. texture.

  5. DETERMINATION OF THERMAL RESPONSE OF CARRARA AND SNEZNIKOVSKY MARBLE USED AS A BUILDING MATERIALS

    OpenAIRE

    Veronika Petráňová; Jaroslav Valach; Alberto Viani; Marta Peréz Estébanez

    2016-01-01

    Physical weathering of marble, widely used as a cladding material on buildings, is one of the most common damaging mechanism caused by anisotropic thermal expansion of calcite grains. The extent of marble deterioration depends mainly on stone fabric and texture. Dry cuboids of Carrara marble and marble from Dolni Morava quarry were subjected to microscopic analysis and thermal cycling, to determine the thermal expansion related to stone fabric and predominant lattice orientation of grains (i....

  6. Negative thermal expansion materials

    International Nuclear Information System (INIS)

    Evans, J.S.O.

    1997-01-01

    The recent discovery of negative thermal expansion over an unprecedented temperature range in ZrW 2 O 8 (which contracts continuously on warming from below 2 K to above 1000 K) has stimulated considerable interest in this unusual phenomenon. Negative and low thermal expansion materials have a number of important potential uses in ceramic, optical and electronic applications. We have now found negative thermal expansion in a large new family of materials with the general formula A 2 (MO 4 ) 3 . Chemical substitution dramatically influences the thermal expansion properties of these materials allowing the production of ceramics with negative, positive or zero coefficients of thermal expansion, with the potential to control other important materials properties such as refractive index and dielectric constant. The mechanism of negative thermal expansion and the phase transitions exhibited by this important new class of low-expansion materials will be discussed. (orig.)

  7. Advanced thermal management materials

    CERN Document Server

    Jiang, Guosheng; Kuang, Ken

    2012-01-01

    ""Advanced Thermal Management Materials"" provides a comprehensive and hands-on treatise on the importance of thermal packaging in high performance systems. These systems, ranging from active electronically-scanned radar arrays to web servers, require components that can dissipate heat efficiently. This requires materials capable of dissipating heat and maintaining compatibility with the packaging and dye. Its coverage includes all aspects of thermal management materials, both traditional and non-traditional, with an emphasis on metal based materials. An in-depth discussion of properties and m

  8. Extended two-temperature model for ultrafast thermal response of band gap materials upon impulsive optical excitation

    Energy Technology Data Exchange (ETDEWEB)

    Shin, Taeho [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Samsung Advanced Institute of Technology, Suwon 443-803 (Korea, Republic of); Teitelbaum, Samuel W.; Wolfson, Johanna; Nelson, Keith A., E-mail: kanelson@mit.edu [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Kandyla, Maria [Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139-4307 (United States); Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, Athens 116-35 (Greece)

    2015-11-21

    Thermal modeling and numerical simulations have been performed to describe the ultrafast thermal response of band gap materials upon optical excitation. A model was established by extending the conventional two-temperature model that is adequate for metals, but not for semiconductors. It considers the time- and space-dependent density of electrons photoexcited to the conduction band and accordingly allows a more accurate description of the transient thermal equilibration between the hot electrons and lattice. Ultrafast thermal behaviors of bismuth, as a model system, were demonstrated using the extended two-temperature model with a view to elucidating the thermal effects of excitation laser pulse fluence, electron diffusivity, electron-hole recombination kinetics, and electron-phonon interactions, focusing on high-density excitation.

  9. Thermal fatigue. Materials modelling

    International Nuclear Information System (INIS)

    Siegele, D.; Fingerhuth, J.; Mrovec, M.

    2012-01-01

    In the framework of the ongoing joint research project 'Thermal Fatigue - Basics of the system-, outflow- and material-characteristics of piping under thermal fatigue' funded by the German Federal Ministry of Education and Research (BMBF) fundamental numerical and experimental investigations on the material behavior under transient thermal-mechanical stress conditions (high cycle fatigue V HCF and low cycle fatigue - LCF) are carried out. The primary objective of the research is the further development of simulation methods applied in safety evaluations of nuclear power plant components. In this context the modeling of crack initiation and growth inside the material structure induced by varying thermal loads are of particular interest. Therefore, three scientific working groups organized in three sub-projects of the joint research project are dealing with numerical modeling and simulation at different levels ranging from atomistic to micromechanics and continuum mechanics, and in addition corresponding experimental data for the validation of the numerical results and identification of the parameters of the associated material models are provided. The present contribution is focused on the development and experimental validation of material models and methods to characterize the damage evolution and the life cycle assessment as a result of thermal cyclic loading. The individual purposes of the subprojects are as following: - Material characterization, Influence of temperature and surface roughness on fatigue endurances, biaxial thermo-mechanical behavior, experiments on structural behavior of cruciform specimens and scatter band analysis (IfW Darmstadt) - Life cycle assessment with micromechanical material models (MPA Stuttgart) - Life cycle assessment with atomistic and damage-mechanical material models associated with material tests under thermal fatigue (Fraunhofer IWM, Freiburg) - Simulation of fatigue crack growth, opening and closure of a short crack under

  10. High Thermal Conductivity Materials

    CERN Document Server

    Shinde, Subhash L

    2006-01-01

    Thermal management has become a ‘hot’ field in recent years due to a need to obtain high performance levels in many devices used in such diverse areas as space science, mainframe and desktop computers, optoelectronics and even Formula One racing cars! Thermal solutions require not just taking care of very high thermal flux, but also ‘hot spots’, where the flux densities can exceed 200 W/cm2. High thermal conductivity materials play an important role in addressing thermal management issues. This volume provides readers a basic understanding of the thermal conduction mechanisms in these materials and discusses how the thermal conductivity may be related to their crystal structures as well as microstructures developed as a result of their processing history. The techniques for accurate measurement of these properties on large as well as small scales have been reviewed. Detailed information on the thermal conductivity of diverse materials including aluminum nitride (AlN), silicon carbide (SiC), diamond, a...

  11. Thermal Response Of An Aerated Concrete Wall With Micro-Encapsulated Phase Change Material

    Science.gov (United States)

    Halúzová, Dušana

    2015-06-01

    For many years Phase Change Materials (PCM) have attracted attention due to their ability to store large amounts of thermal energy. This property makes them a candidate for the use of passive heat storage. In many applications, they are used to avoid the overheating of the temperature of an indoor environment. This paper describes the behavior of phase change materials that are inbuilt in aerated concrete blocks. Two building samples of an aerated concrete wall were measured in laboratory equipment called "twin-boxes". The first box consists of a traditional aerated concrete wall; the second one has additional PCM micro-encapsulated in the wall. The heat flux through the wall was measured and compared to simulation results modeled in the ESP-r program. This experimental measurement provides a foundation for a model that can be used to analyze further building constructions.

  12. Development of High-Fidelity Material Response Modeling for Resin-Infused Woven Thermal Protection Systems

    Data.gov (United States)

    National Aeronautics and Space Administration — For future space exploration missions, it is essential for the thermal protection system (TPS) found on hypersonic vehicles or atmospheric entry probes to be...

  13. Thermal Response of UHMWPE Materials in a Flash Flame Test Environment

    Science.gov (United States)

    2014-11-13

    protection. The UHMWPE fabric immediately began disintegrating during the flash flame exposure. During the test, one end of the UHMWPE fabric...UHMWPE material after the test. There were places where the fabric material appeared to have melted and re-solidified, creating areas of solid plastic ...and Observations The midscale test results showed that any direct flame on the UHMWPE materials will cause rapid disintegration of the material

  14. Thermally and Chemically responsive nanoporous materials for efficient capture of fission product gases.

    Energy Technology Data Exchange (ETDEWEB)

    Stroeve, Pieter; Faller, Roland

    2018-04-24

    The objective of this project was to develop robust, high-efficiency materials for capture of fission product gases such as He, Xe and Kr in scenarios relevant for both reactor fuels and reprocessing operations. The relevant environments are extremely harsh, encompassing temperatures up to 1500 °C, high levels of radiation, as well as potential exposures to highly-reactive chemicals such as nitric acid and organic solvents such as kerosene. The requirement for nanostructured capture materials is driven in part by the very short (few micron) diffusion distances for product gases in nuclear fuel.1-2 We achieved synthesis, characterization and detailed modeling of the materials. Although not all materials reviewed in this report will be feasible for the ultimate goal of integration in nuclear fuel, nevertheless each material studied has particular properties which will enable an optimized material to be efficiently developed and characterized.

  15. Transient thermal response of a packed bed for energy storage unit utilizing phase change material: experimental and numerical study

    International Nuclear Information System (INIS)

    Bemansour, A.

    2006-01-01

    The present work concerns the numerical and experimental study of the transient response of a packed bed latent heat thermal energy storage system. Experiments were carried out to measures the transient temperature distributions inside a cylindrical bed, which is randomly packed with spheres having uniform sizes and encapsulated the paraffin wax as a phase change material (PCM), with air as a working fluid. A two-dimensional separate phases formulation is used to develop a numerical analysis of the transient response of the bed, considering the influence of both axial and radial thermal dispersion. The fluid energy equation was transformed by finite difference approximation and solved by alternating direction implicit scheme, while the PCM energy equation was solved using fully explicit scheme. This analysis can be applied for both charging and recovery modes and a broad range of Reynolds numbers. Measurements of both fluid and PCM temperature were conducted at different axial and radial positions and at different operating parameters. Experimental measurements of temperature distribution compare favorably with the numerical results over a broad range of Reynolds numbers.(Author)

  16. Analysis of the thermal response of a BWR Mark-I containment shell to direct contact by molten core materials

    International Nuclear Information System (INIS)

    Kress, T.S.; Cleveland, J.C.

    1988-01-01

    This study was undertaken to evaluate the thermal response of a BWR Mark-I containment shell in the event of an accident severe enough for molten core materials to fall into the cavity beneath the rector vessel and eventually come into direct contact with the shell. An existing ORNL three-dimensional transient heat transport computer code, HEATING-6, was used for a specific 2-D case (and variations) for which representative melt/shell boundary conditions required as input were available from other studies. In addition to the use of HEATING-6, a simplified analytical steady-state correlation was developed and given the name BWR Liner Analysis Program (BWRLAP). BWRLAP was ''benchmarked'' by comparison with HEATING-6 and was then used to make a number of parametric calculations to investigate the sensitivities of the results to the inputs. 5 refs., 11 figs., 2 tabs

  17. Thermal transfer in multilayer materials

    Energy Technology Data Exchange (ETDEWEB)

    Bouayad, H.; Mokhtari, A.; Martin, C.; Fauchais, P. [Laboratoire de Materiaux Ceramiques et Traitements de Surface, 87 - Limoges (France)

    1993-12-31

    It is easier to measure the thermal diffusivity (a) of material rather than its thermal conductivity (k), a simple relationship (k=a cp) allowing to calculate k provided and cp are measured. However this relationship applies only if the considered material is homogenous. For composite materials, especially for multilayers ones, we have developed an analytical model and a numerical one. The first one allows to determine the thermal diffusivity and conductivity of a two-layer material. The second one allows to determine the thermal diffusivity of one of the layers provided the values of (a) are known for the two other layers (for a two or three-layer material). The use of the two models to calculate the apparent diffusivity of a two layer material results in values in fairly good agreement. (Authors). 4 refs., 3 figs., 3 tabs.

  18. Response of Primary Human Bone Marrow Mesenchymal Stromal Cells and Dermal Keratinocytes to Thermal Printer Materials In Vitro.

    Science.gov (United States)

    Schmelzer, Eva; Over, Patrick; Gridelli, Bruno; Gerlach, Jörg C

    Advancement in thermal three-dimensional printing techniques has greatly increased the possible applications of various materials in medical applications and tissue engineering. Yet, potential toxic effects on primary human cells have been rarely investigated. Therefore, we compared four materials commonly used in thermal printing for bioengineering, namely thermally printed acrylonitrile butadiene styrene, MED610, polycarbonate, and polylactic acid, and investigated their effects on primary human adult skin epidermal keratinocytes and bone marrow mesenchymal stromal cells (BM-MSCs) in vitro. We investigated indirect effects on both cell types caused by potential liberation of soluble substances from the materials, and also analyzed BM-MSCs in direct contact with the materials. We found that even in culture without direct contact with the materials, the culture with MED610 (and to a lesser extent acrylonitrile butadiene styrene) significantly affected keratinocytes, reducing cell numbers and proliferation marker Ki67 expression, and increasing glucose consumption, lactate secretion, and expression of differentiation-associated genes. BM-MSCs had decreased metabolic activity, and exhibited increased cell death in direct culture on the materials. MED610 and acrylonitrile butadiene styrene induced the strongest expression of genes associated to differentiation and estrogen receptor activation. In conclusion, we found strong cell-type-specific effects of the materials, suggesting that materials for applications in regenerative medicine should be carefully selected not only based on their mechanical properties but also based on their cell-type-specific biological effects.

  19. Microwavable thermal energy storage material

    Science.gov (United States)

    Salyer, I.O.

    1998-09-08

    A microwavable thermal energy storage material is provided which includes a mixture of a phase change material and silica, and a carbon black additive in the form of a conformable dry powder of phase change material/silica/carbon black, or solid pellets, films, fibers, moldings or strands of phase change material/high density polyethylene/ethylene vinyl acetate/silica/carbon black which allows the phase change material to be rapidly heated in a microwave oven. The carbon black additive, which is preferably an electrically conductive carbon black, may be added in low concentrations of from 0.5 to 15% by weight, and may be used to tailor the heating times of the phase change material as desired. The microwavable thermal energy storage material can be used in food serving applications such as tableware items or pizza warmers, and in medical wraps and garments. 3 figs.

  20. Thermal conductivity of granular materials

    Energy Technology Data Exchange (ETDEWEB)

    Buyevich, Yu A

    1974-01-01

    Stationary heat transfer in a granular material consisting of a continuous medium containing spherical granules of other substances is considered under the assumption that the spatial distribution of granules is random. The effective thermal conductivity characterizing macroscopic heat transfer in such a material is expressed as a certain function of the conductivities and volume fractions of the medium and dispersed substances. For reasons of mathematical analogy, all the results obtained for the thermal conductivity are valid while computing the effective diffusivity of some admixture in granular materials as well as for evaluation of the effective electric conductivity or the mean dielectric and magnetic permeabilities of granular conductors and dielectrics. (23 refs.)

  1. Anisotropic thermal expansion in flexible materials

    Science.gov (United States)

    Romao, Carl P.

    2017-10-01

    A definition of the Grüneisen parameters for anisotropic materials is derived based on the response of phonon frequencies to uniaxial stress perturbations. This Grüneisen model relates the thermal expansion in a given direction (αi i) to one element of the elastic compliance tensor, which corresponds to the Young's modulus in that direction (Yi i). The model is tested through ab initio prediction of thermal expansion in zinc, graphite, and calcite using density functional perturbation theory, indicating that it could lead to increased accuracy for structurally complex systems. The direct dependence of αi i on Yi i suggests that materials which are flexible along their principal axes but rigid in other directions will generally display both positive and negative thermal expansion.

  2. Biological Responses to Materials

    Science.gov (United States)

    Anderson, James M.

    2001-08-01

    All materials intended for application in humans as biomaterials, medical devices, or prostheses undergo tissue responses when implanted into living tissue. This review first describes fundamental aspects of tissue responses to materials, which are commonly described as the tissue response continuum. These actions involve fundamental aspects of tissue responses including injury, inflammatory and wound healing responses, foreign body reactions, and fibrous encapsulation of the biomaterial, medical device, or prosthesis. The second part of this review describes the in vivo evaluation of tissue responses to biomaterials, medical devices, and prostheses to determine intended performance characteristics and safety or biocompatibility considerations. While fundamental aspects of tissue responses to materials are important from research and development perspectives, the in vivo evaluation of tissue responses to these materials is important for performance, safety, and regulatory reasons.

  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. Thermal Responsive Envelope

    DEFF Research Database (Denmark)

    Foged, Isak Worre; Pasold, Anke

    2015-01-01

    The paper presents an architectural computational method and model, which, through additive and subtractive processes, create composite elements with bending behaviour based on thermal variations in the surrounding climatic environment. The present effort is focused on the manipulation of assembly...... alterations, their respective durability and copper’s architectural (visual and transformative) aesthetic qualities. Through the use of an evolutionary solver, the composite structure of the elements are organised to find the bending behaviour specified by and for the thermal environments. The entire model...... in which the behavioural composites are organised in modules and how they act and perform. Furthermore, a large full-scale prototype is made as a demonstrator and experimental setup for post-construct analysis and evaluation of the design research. The work finds that the presented method and model can...

  5. Thermal cycling fatigue of organic thermal interface materials using a thermal-displacement measurement technique

    Science.gov (United States)

    Steill, Jason Scott

    The long term reliability of polymer-based thermal interface materials (TIM) is essential for modern electronic packages which require robust thermal management. The challenge for today's materials scientists and engineers is to maximize the heat flow from integrated circuits through a TIM and out the heat sink. Thermal cycling of the electronic package and non-uniformity in the heat flux with respect to the plan area can lead to void formation and delamination which re-introduces inefficient heat transfer. Measurement and understanding at the nano-scale is essential for TIM development. Finding and documenting the evolution of the defects is dependent upon a full understanding of the thermal probes response to changing environmental conditions and the effects of probe usage. The response of the thermal-displacement measurement technique was dominated by changes to the environment. Accurate measurement of the thermal performance was hindered by the inability to create a model system and control the operating conditions. This research highlights the need for continued study into the probe's thermal and mechanical response using tightly controlled test conditions.

  6. High thermal conductivity materials for thermal management applications

    Science.gov (United States)

    Broido, David A.; Reinecke, Thomas L.; Lindsay, Lucas R.

    2018-05-29

    High thermal conductivity materials and methods of their use for thermal management applications are provided. In some embodiments, a device comprises a heat generating unit (304) and a thermally conductive unit (306, 308, 310) in thermal communication with the heat generating unit (304) for conducting heat generated by the heat generating unit (304) away from the heat generating unit (304), the thermally conductive unit (306, 308, 310) comprising a thermally conductive compound, alloy or composite thereof. The thermally conductive compound may include Boron Arsenide, Boron Antimonide, Germanium Carbide and Beryllium Selenide.

  7. Radiation damage and thermal shock response of carbon-fiber-reinforced materials to intense high-energy proton beams

    Directory of Open Access Journals (Sweden)

    N. Simos

    2016-11-01

    Full Text Available A comprehensive study on the effects of energetic protons on carbon-fiber composites and compounds under consideration for use as low-Z pion production targets in future high-power accelerators and low-impedance collimating elements for intercepting TeV-level protons at the Large Hadron Collider has been undertaken addressing two key areas, namely, thermal shock absorption and resistance to irradiation damage. Carbon-fiber composites of various fiber weaves have been widely used in aerospace industries due to their unique combination of high temperature stability, low density, and high strength. The performance of carbon-carbon composites and compounds under intense proton beams and long-term irradiation have been studied in a series of experiments and compared with the performance of graphite. The 24-GeV proton beam experiments confirmed the inherent ability of a 3D C/C fiber composite to withstand a thermal shock. A series of irradiation damage campaigns explored the response of different C/C structures as a function of the proton fluence and irradiating environment. Radiolytic oxidation resulting from the interaction of oxygen molecules, the result of beam-induced radiolysis encountered during some of the irradiation campaigns, with carbon atoms during irradiation with the presence of a water coolant emerged as a dominant contributor to the observed structural integrity loss at proton fluences ≥5×10^{20}  p/cm^{2}. The carbon-fiber composites were shown to exhibit significant anisotropy in their dimensional stability driven by the fiber weave and the microstructural behavior of the fiber and carbon matrix accompanied by the presence of manufacturing porosity and defects. Carbon-fiber-reinforced molybdenum-graphite compounds (MoGRCF selected for their impedance properties in the Large Hadron Collider beam collimation exhibited significant decrease in postirradiation load-displacement behavior even after low dose levels (∼5×10^{18}

  8. 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.

  9. Material Response Characterization

    Science.gov (United States)

    1977-08-01

    models fit to vertical UX and TX data and a mean stress tension cutoff criterion. Because tests on the Kayenta sands one materials had revealed a definite...parameters. 9 This data characterizing the anisotropic response of the upper 30 feet of Kayenta material should not just be filed away; it should be used...9. Johnson, J. N., et al, "Anisotropic Mechanical Properties of Kayenta Sandstone (MIXED COMPANY Site) for Ground Motion Calculations," Terra Tek TR

  10. Mechanical Response of Thermoelectric Materials

    Energy Technology Data Exchange (ETDEWEB)

    Wereszczak, Andrew A. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Case, Eldon D. [Michigan State Univ., East Lansing, MI (United States)

    2015-05-01

    A sufficient mechanical response of thermoelectric materials (TEMats) to structural loadings is a prerequisite to the exploitation of any candidate TEMat's thermoelectric efficiency. If a TEMat is mechanically damaged or cracks from service-induced stresses, then its thermal and electrical functions can be compromised or even cease. Semiconductor TEMats tend to be quite brittle and have a high coefficient of thermal expansion; therefore, they can be quite susceptible to mechanical failure when subjected to operational thermal gradients. Because of this, sufficient mechanical response (vis-a-vis, mechanical properties) of any candidate TEMat must be achieved and sustained in the context of the service-induced stress state to which it is subjected. This report provides an overview of the mechanical responses of state-of-the-art TEMats; discusses the relevant properties that are associated with those responses and their measurement; and describes important, nonequilibrium phenomena that further complicate their use in thermoelectric devices. For reference purposes, the report also includes several appendixes that list published data on elastic properties and strengths of a variety of TEMats.

  11. 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.

  12. Light intensity and thermal responses

    NARCIS (Netherlands)

    te Kulve, M.; Schellen, L.; Schlangen, L.; Frijns, A.J.H.; van Marken Lichtenbelt, W.D.; Nicol, Fergus; Roaf, Susan; Brotas, Luisa; Humphreys, Michael

    2016-01-01

    Temperature and light are both major factors in the design of a comfortable indoor environment. Moreover, there might be an interaction between light exposure and human thermal responses. However, results of experiments conducted so far are inconclusive and current understanding of the relation

  13. Phase change material thermal capacitor clothing

    Science.gov (United States)

    Buckley, Theresa M. (Inventor)

    2005-01-01

    An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  14. Preparation and characterization of thermal-responsive non-woven poly (propylene) materials grafted with N-isopropylacrylamide/β-cyclodextrin

    DEFF Research Database (Denmark)

    Amiri, Setareh; Zadhoush, Ali; Mallakpour, Shadpour

    2013-01-01

    A temperature-sensitive hydrogel was successfully grafted on the surface of non-woven poly(propylene) materials. This was carried out by the application of unmodified β-cyclodextrin and N-isopropylacrylamide monomer in order to develop new functional hydrogels for textile science and technology......(N-isopropylacrylamide) and β-cyclodextrin components on the surface of the textile. Unmodified β-cyclodextrin content was estimated by the use of elemental analysis to be 97 µg/cm2. The water uptake measurements and differential scanning calorimetry analyses showed that the hydrogel maintained its temperature...... of smart textiles which possess the temperature-sensitive property of poly(N-isopropylacrylamide) and the ability of inclusion complex formation with guest molecules due to the presence of unmodified β-cyclodextrin in the hydrogel network....

  15. Study of thermal sensitivity and thermal explosion violence of energetic materials in the LLNL ODTX system

    International Nuclear Information System (INIS)

    Hsu, P C; Hust, G; Zhang, M X; Lorenz, T K; Reynolds, J G; Fried, L; Springer, H K; Maienschein, J L

    2014-01-01

    Incidents caused by fire and combat operations can heat energetic materials that may lead to thermal explosion and result in structural damage and casualty. Some explosives may thermally explode at fairly low temperatures (< 100 °C) and the violence from thermal explosion may cause significant damage. Thus it is important to understand the response of energetic materials to thermal insults. The One Dimensional Time to Explosion (ODTX) system at the Lawrence Livermore National Laboratory has been used for decades to measure times to explosion, threshold thermal explosion temperature, and determine kinetic parameters of energetic materials. Samples of different configurations (pressed part, powder, paste, and liquid) can be tested in the system. The ODTX testing can also provide useful data for assessing the thermal explosion violence of energetic materials. Recent ODTX experimental data are reported in the paper.

  16. Controlling Thermal Conduction by Graded Materials

    Science.gov (United States)

    Ji, Qin; Huang, Ji-Ping

    2018-04-01

    Manipulating thermal conductivities are fundamentally important for controlling the conduction of heat at will. Thermal cloaks and concentrators, which have been extensively studied recently, are actually graded materials designed according to coordinate transformation approaches, and their effective thermal conductivity is equal to that of the host medium outside the cloak or concentrator. Here we attempt to investigate a more general problem: what is the effective thermal conductivity of graded materials? In particular, we perform a first-principles approach to the analytic exact results of effective thermal conductivities of materials possessing either power-law or linear gradation profiles. On the other hand, by solving Laplace’s equation, we derive a differential equation for calculating the effective thermal conductivity of a material whose thermal conductivity varies along the radius with arbitrary gradation profiles. The two methods agree with each other for both external and internal heat sources, as confirmed by simulation and experiment. This work provides different methods for designing new thermal metamaterials (including thermal cloaks and concentrators), in order to control or manipulate the transfer of heat. Support by the National Natural Science Foundation of China under Grant No. 11725521, by the Science and Technology Commission of Shanghai Municipality under Grant No. 16ZR1445100

  17. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.H.

    1992-09-01

    Two legal-weight truck casks the GA-4 and GA-9, will carry four PWR and nine BWR spent fuel assemblies, respectively. Each cask has a solid neutron shielding material separating the steel body and the outer steel skin. In the thermal accident specified by NRC regulations in 10CFR Part 71, the cask is subjected to an 800 degree C environment for 30 minutes. The neutron shield need not perform any shielding function during or after the thermal accident, but its behavior must not compromise the ability of the cask to contain the radioactive contents. In May-June 1989 the first series of full-scale thermal tests was performed on three shielding materials: Bisco Products NS-4-FR, and Reactor Experiments RX-201 and RX-207. The tests are described in Thermal Testing of Solid Neutron Shielding Materials, GA-AL 9897, R. H. Boonstra, General Atomics (1990), and demonstrated the acceptability of these materials in a thermal accident. Subsequent design changes to the cask rendered these materials unattractive in terms of weight or adequate service temperature margin. For the second test series, a material specification was developed for a polypropylene based neutron shield with a softening point of at least 280 degree F. The neutron shield materials tested were boronated (0.8--4.5%) polymers (polypropylene, HDPE, NS-4). The Envirotech and Bisco materials are not polypropylene, but were tested as potential backup materials in the event that a satisfactory polypropylene could not be found

  18. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.H.

    1990-03-01

    The GA-4 and GA-9 spent fuel shipping casks employ a solid neutron shielding material. During a hypothetical thermal accident, any combustion of the neutron shield must not compromise the ability of the cask to contain the radioactive contents. A two-phase thermal testing program was carried out to assist in selecting satisfactory shielding materials. In the first phase, small-scale screening tests were performed on nine candidate materials using ASTM procedures. From these initial results, three of the nine candidates were chosen for inclusion in the second phase of testing, These materials were Bisco Products NS-4-FR, Reactor Experiments 201-1, and Reactor Experiments 207. In the second phase, each selected material was fabricated into a test article which simulated a full-scale of neutron shield from the cask. The test article was heated in an environmental prescribed by NRC regulations. Results of this second testing phase showed that all three materials are thermally acceptable

  19. Nonreciprocal Thermal Material by Spatiotemporal Modulation

    Science.gov (United States)

    Torrent, Daniel; Poncelet, Olivier; Batsale, Jean-Chirstophe

    2018-03-01

    The thermal properties of a material with a spatiotemporal modulation, in the form of a traveling wave, in both the thermal conductivity and the specific heat capacity are studied. It is found that these materials behave as materials with an internal convectionlike term that provides them with nonreciprocal properties, in the sense that the heat flux has different properties when it propagates in the same direction or in the opposite one to the modulation of the parameters. An effective medium description is presented which accurately describes the modulated material, and numerical simulations support this description and verify the nonreciprocal properties of the material. It is found that these materials are promising candidates for the design of thermal diodes and other advanced devices for the control of the heat flow at all scales.

  20. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.N.

    1990-01-01

    The GA-4 and GA-9 spent fuel shipping casks employ a solid neutron shielding material. During a hypothetical thermal accident, any combustion of the neutron shield must not compromise the ability of the cask to contain the radioactive contents. A two-phase thermal testing program was carried out to assist in selecting satisfactory shielding materials. In the first phase, small-scale screening tests were performed on nine candidate materials using ASTM procedures. From these initial results, three of the nine candidates were chosen for inclusion in the second phase of testing. These materials were Bisco Products NS-4-FR, Reactor Experiments 201-1, and Reactor Experiments 207. In the second phase, each selected material was fabricated into a test article which simulated a full-scale section of neutron shield from the cask. The test article was heated in an environment prescribed by NRC regulations. Results of this second testing phase show that all three materials are thermally acceptable

  1. Modeling Thermal Ignition of Energetic Materials

    National Research Council Canada - National Science Library

    Gerri, Norman J; Berning, Ellen

    2004-01-01

    This report documents an attempt to computationally simulate the mechanics and thermal regimes created when a threat perforates an armor envelope and comes in contact with stowed energetic material...

  2. Thermal response in van der Waals heterostructures

    KAUST Repository

    Gandi, Appala

    2016-11-21

    We solve numerically the Boltzmann transport equations of the phonons and electrons to understand the thermoelectric response in heterostructures of M2CO2 (M: Ti, Zr, Hf) MXenes with transition metal dichalcogenide monolayers. Low frequency optical phonons are found to occur as a consequence of the van der Waals bonding, contribute significantly to the thermal transport, and compensate for the reduced contributions of the acoustic phonons (increased scattering cross-sections in heterostructures), such that the thermal conductivities turn out to be similar to those of the bare MXenes. Our results indicate that the important superlattice design approach of thermoelectrics (to reduce the thermal conductivity) may be effective for two-dimensional van der Waals materials when used in conjunction with intercalation. © 2016 IOP Publishing Ltd.

  3. Thermal testing of solid neutron shielding materials

    International Nuclear Information System (INIS)

    Boonstra, R.H.

    1993-01-01

    In May-June 1989 the first series of full-scale thermal tests was performed on three shielding materials: Bisco Products NS-4-FR, and Reactor Experiments RX-201 and RX-207. The tests are described in Thermal Testing of Solid Neutron Shielding Materials, GA-A19897, R.H. Boonstra, General Atomics (1990), and demonstrated the acceptability of these materials in a thermal accident. Subsequent design changes to the cask rendered these materials unattractive in terms of weight or adequate service temperature margin. For the second test series a material specification was developed for a polypropylene based neutron shield with a softening point of at least 280degF. Table 1 lists the neutron shield materials tested. The Envirotech and Bisco materials are not polypropylene, but were tested as potential backup materials in the event that a satisfactory polypropylene could not be found. The Bisco modified NS-4 and Reactor Experiments HMPP are both acceptable materials from a thermal accident standpoint for use in the shipping cask. Tests of the Kobe PP-R01 and Envirotech HDPE were stopped for safety reasons, due to inability to deal with the heavy smoke, before completion of the 30-minute heating phase. However these materials may prove satisfactory if they could undergo the complete heating. (J.P.N.)

  4. Polymeric materials for solar thermal applications

    CERN Document Server

    Köhl, Michael; Papillon, Philippe; Wallner, Gernot M; Saile, Sandrin

    2012-01-01

    Bridging the gap between basic science and technological applications, this is the first book devoted to polymers for solar thermal applications.Clearly divided into three major parts, the contributions are written by experts on solar thermal applications and polymer scientists alike. The first part explains the fundamentals of solar thermal energy especially for representatives of the plastics industry and researchers. Part two then goes on to provide introductory information on polymeric materials and processing for solar thermal experts. The third part combines both of these fields, dis

  5. Materials and Manufacturing Technology Directorate Thermal Sciences and Materials Branch (Overview)

    Science.gov (United States)

    2010-09-01

    Molecular Mechanics for thermo-mechanical response Materials Characterization • CNT modified durable thermal interface ( DTI ) • MEMS-based RTD micro...stabilization. Surface Characterization by Atomic Force Microscopy: Probing Thermal, Electrical, and Mechanical Properties Heater Current Path Anchor Leg 50 µm

  6. Structure and thermal stability of nanocrystalline materials

    Indian Academy of Sciences (India)

    In addition, study of the thermal stability of nanocrystalline materials against significant grain growth is both scientific and technological interest. A sharp increase in grain size (to micron levels) during consolidation of nanocrystalline powders to obtain fully dense materials may consequently result in the loss of some unique ...

  7. Sprayable Phase Change Coating Thermal Protection Material

    Science.gov (United States)

    Richardson, Rod W.; Hayes, Paul W.; Kaul, Raj

    2005-01-01

    NASA has expressed a need for reusable, environmentally friendly, phase change coating that is capable of withstanding the heat loads that have historically required an ablative thermal insulation. The Space Shuttle Program currently relies on ablative materials for thermal protection. The problem with an ablative insulation is that, by design, the material ablates away, in fulfilling its function of cooling the underlying substrate, thus preventing the insulation from being reused from flight to flight. The present generation of environmentally friendly, sprayable, ablative thermal insulation (MCC-l); currently use on the Space Shuttle SRBs, is very close to being a reusable insulation system. In actual flight conditions, as confirmed by the post-flight inspections of the SRBs, very little of the material ablates. Multi-flight thermal insulation use has not been qualified for the Space Shuttle. The gap that would have to be overcome in order to implement a reusable Phase Change Coating (PCC) is not unmanageable. PCC could be applied robotically with a spray process utilizing phase change material as filler to yield material of even higher strength and reliability as compared to MCC-1. The PCC filled coatings have also demonstrated potential as cryogenic thermal coatings. In experimental thermal tests, a thin application of PCC has provided the same thermal protection as a much thicker and heavier application of a traditional ablative thermal insulation. In addition, tests have shown that the structural integrity of the coating has been maintained and phase change performance after several aero-thermal cycles was not affected. Experimental tests have also shown that, unlike traditional ablative thermal insulations, PCC would not require an environmental seal coat, which has historically been required to prevent moisture absorption by the thermal insulation, prevent environmental degradation, and to improve the optical and aerodynamic properties. In order to reduce

  8. Phase Change Materials for Thermal Energy Storage

    OpenAIRE

    Stiebra, L; Cabulis, U; Knite, M

    2014-01-01

    Phase change materials (PCMs) for thermal energy storage (TES) have become an important subject of research in recent years. Using PCMs for thermal energy storage provides a solution to increase the efficiency of the storage and use of energy in many domestic and industrial sectors. Phase change TES systems offer a number of advantages over other systems (e.g. chemical storage systems): particularly small temperature distance between the storage and retrieval cycles, small unit sizes and lo...

  9. Passive thermal management using phase change materials

    Science.gov (United States)

    Ganatra, Yash Yogesh

    The trend of enhanced functionality and reducing thickness of mobile devices has. led to a rapid increase in power density and a potential thermal bottleneck since. thermal limits of components remain unchanged. Active cooling mechanisms are not. feasible due to size, weight and cost constraints. This work explores the feasibility. of a passive cooling system based on Phase Change Materials (PCMs) for thermal. management of mobile devices. PCMs stabilize temperatures due to the latent heat. of phase change thus increasing the operating time of the device before threshold. temperatures are exceeded. The primary contribution of this work is the identification. of key parameters which influence the design of a PCM based thermal management. system from both the experiments and the numerical models. This work first identifies strategies for integrating PCMs in an electronic device. A. detailed review of past research, including experimental techniques and computational. models, yields key material properties and metrics to evaluate the performance of. PCMs. Subsequently, a miniaturized version of a conventional thermal conductivity. measurement technique is developed to characterize thermal resistance of PCMs. Further, latent heat and transition temperatures are also characterized for a wide. range of PCMs. In-situ measurements with PCMs placed on the processor indicate that some. PCMs can extend the operating time of the device by as much as a factor of 2.48. relative to baseline tests (with no PCMs). This increase in operating time is investigated. by computational thermal models that explore various integration locations, both at the package and device level.

  10. Thermal conductivity of highly porous mullite material

    International Nuclear Information System (INIS)

    Barea, Rafael; Osendi, Maria Isabel; Ferreira, Jose M.F.; Miranzo, Pilar

    2005-01-01

    The thermal diffusivity of highly porous mullite materials (35-60 vol.% porosity) has been measured up to 1000 deg C by the laser flash method. These materials were fabricated by a direct consolidation method based on the swelling properties of starch granules in concentrated aqueous suspensions and showed mainly spherical shaped pores of about 30 μm in diameter. From the point of view of heat conduction, they behave as a bi-phase material of voids dispersed in the continuous mullite matrix. The temperature dependence of thermal conductivity for the different porosities was modeled by a simple equation that considers the contribution to heat conduction of the mullite matrix and the gas inside the pores, as well as the radiation. The thermal conductivity of the matrix was taken from the measurements done in a dense mullite while the conductivity in the voids was assumed to be that of the testing atmosphere

  11. Reliability of thermal interface materials: A review

    International Nuclear Information System (INIS)

    Due, Jens; Robinson, Anthony J.

    2013-01-01

    Thermal interface materials (TIMs) are used extensively to improve thermal conduction across two mating parts. They are particularly crucial in electronics thermal management since excessive junction-to-ambient thermal resistances can cause elevated temperatures which can negatively influence device performance and reliability. Of particular interest to electronic package designers is the thermal resistance of the TIM layer at the end of its design life. Estimations of this allow the package to be designed to perform adequately over its entire useful life. To this end, TIM reliability studies have been performed using accelerated stress tests. This paper reviews the body of work which has been performed on TIM reliability. It focuses on the various test methodologies with commentary on the results which have been obtained for the different TIM materials. Based on the information available in the open literature, a test procedure is proposed for TIM selection based on beginning and end of life performance. - Highlights: ► This paper reviews the body of work which has been performed on TIM reliability. ► Test methodologies for reliability testing are outlined. ► Reliability results for the different TIM materials are discussed. ► A test procedure is proposed for TIM selection BOLife and EOLife performance.

  12. Thermal Expansion Properties of Aerospace Materials

    Science.gov (United States)

    Green, E. F.

    1969-01-01

    Thermal expansion properties of materials used in aerospace systems are compiled into a single handbook. The data, derived from experimental measurements supplemented by information from literature sources, are presented in charts and tables arranged in two sections, covering cryogenic and elevated temperatures.

  13. Advanced materials for thermal protection system

    Science.gov (United States)

    Heng, Sangvavann; Sherman, Andrew J.

    1996-03-01

    Reticulated open-cell ceramic foams (both vitreous carbon and silicon carbide) and ceramic composites (SiC-based, both monolithic and fiber-reinforced) were evaluated as candidate materials for use in a heat shield sandwich panel design as an advanced thermal protection system (TPS) for unmanned single-use hypersonic reentry vehicles. These materials were fabricated by chemical vapor deposition/infiltration (CVD/CVI) and evaluated extensively for their mechanical, thermal, and erosion/ablation performance. In the TPS, the ceramic foams were used as a structural core providing thermal insulation and mechanical load distribution, while the ceramic composites were used as facesheets providing resistance to aerodynamic, shear, and erosive forces. Tensile, compressive, and shear strength, elastic and shear modulus, fracture toughness, Poisson's ratio, and thermal conductivity were measured for the ceramic foams, while arcjet testing was conducted on the ceramic composites at heat flux levels up to 5.90 MW/m2 (520 Btu/ft2ṡsec). Two prototype test articles were fabricated and subjected to arcjet testing at heat flux levels of 1.70-3.40 MW/m2 (150-300 Btu/ft2ṡsec) under simulated reentry trajectories.

  14. Thermal conductivity of fusion solid breeder materials

    International Nuclear Information System (INIS)

    Liu, Y.Y.; Tam, S.W.

    1986-06-01

    Several simple and useful formulae for estimating the thermal conductivity of lithium-containing ceramic tritium breeder materials for fusion reactor blankets are given. These formulae account for the effects of irradiation, as well as solid breeder configuration, i.e., monolith or a packed bed. In the latter case, a coated-sphere concept is found more attractive in incorporating beryllia (a neutron multiplier) into the blanket than a random mixture of solid breeder and beryllia spheres

  15. Local behaviour of negative thermal expansion materials

    International Nuclear Information System (INIS)

    Fornasini, P.; Dalba, G.; Grisenti, R.; Purans, J.; Vaccari, M.; Rocca, F.; Sanson, A.

    2006-01-01

    EXAFS can represent a powerful probe of the local behaviour of negative thermal expansion (NTE) materials, thanks to the possibility of measuring the expansion of selected inter-atomic bonds and the perpendicular relative atomic displacements. The effectiveness of EXAFS for NTE studies is illustrated by a comparison of results recently obtained on germanium, CuCl and the cuprites Cu 2 O and Ag 2 O

  16. Thermally Conductive Structural 2D Composite Materials

    Science.gov (United States)

    2012-08-14

    Dimensional Pitch Polyimide Composite Micrographs ........ 27 Figure 23. 4-Ply Silver Polyimide Laminate ...through-thickness thermal conductivity of up to 20 W/m.K. This novel structural prepreg material will be developed through engineering of an optimal fiber...with an EPON 862/Epikure W epoxy resin system to form unidirectional prepreg tapes. Each prepreg was then cut to 6 inch by 6 inch plies and

  17. Thermal Energy Storage with Phase Change Material

    Directory of Open Access Journals (Sweden)

    Lavinia Gabriela SOCACIU

    2012-08-01

    Full Text Available Thermal energy storage (TES systems provide several alternatives for efficient energy use and conservation. Phase change materials (PCMs for TES are materials supplying thermal regulation at particular phase change temperatures by absorbing and emitting the heat of the medium. TES in general and PCMs in particular, have been a main topic in research for the last 30 years, but although the information is quantitatively enormous, it is also spread widely in the literature, and difficult to find. PCMs absorb energy during the heating process as phase change takes place and release energy to the environment in the phase change range during a reverse cooling process. PCMs possesses the ability of latent thermal energy change their state with a certain temperature. PCMs for TES are generally solid-liquid phase change materials and therefore they need encapsulation. TES systems using PCMs as a storage medium offers advantages such as high TES capacity, small unit size and isothermal behaviour during charging and discharging when compared to the sensible TES.

  18. Impact Response of Thermally Sprayed Metal Deposits

    Science.gov (United States)

    Wise, J. L.; Hall, A. C.; Moore, N. W.; Pautz, S. D.; Franke, B. C.; Scherzinger, W. M.; Brown, D. W.

    2017-06-01

    Gas-gun experiments have probed the impact response of tantalum specimens that were additively manufactured using a controlled thermal spray deposition process. Velocity interferometer (VISAR) diagnostics provided time-resolved measurements of sample response under one-dimensional (i . e . , uniaxial strain) shock compression to peak stresses ranging between 1 and 4 GPa. The acquired wave-profile data have been analyzed to determine the Hugoniot Elastic Limit (HEL), Hugoniot equation of state, and high-pressure yield strength of the thermally deposited samples for comparison to published baseline results for conventionally wrought tantalum. The effects of composition, porosity, and microstructure (e . g . , grain/splat size and morphology) are assessed to explain differences in the dynamic mechanical behavior of spray-deposited versus conventional material. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  19. Negative thermal expansion materials: technological key for control of thermal expansion

    OpenAIRE

    Koshi Takenaka

    2012-01-01

    Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining pra...

  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. Radiative thermal rectification using superconducting materials

    Energy Technology Data Exchange (ETDEWEB)

    Nefzaoui, Elyes, E-mail: elyes.nefzaoui@univ-poitiers.fr; Joulain, Karl, E-mail: karl.joulain@univ-poitiers.fr; Drevillon, Jérémie; Ezzahri, Younès [Institut Pprime, Université de Poitiers-CNRS-ENSMA, 2, Rue Pierre Brousse, Bâtiment B25, TSA 41105, 86073 Poitiers Cedex 9 (France)

    2014-03-10

    Thermal rectification can be defined as an asymmetry in the heat flux when the temperature difference between two interacting thermal reservoirs is reversed. In this Letter, we present a far-field radiative thermal rectifier based on high-temperature superconducting materials with a rectification ratio up to 80%. This value is among the highest reported in literature. Two configurations are examined: a superconductor (Tl{sub 2}Ba{sub 2}CaCu{sub 2}O{sub 8}) exchanging heat with (1) a black body and (2) another superconductor, YBa{sub 2}Cu{sub 3}O{sub 7} in this case. The first configuration shows a higher maximal rectification ratio. Besides, we show that the two-superconductor rectifier exhibits different rectification regimes depending on the choice of the reference temperature, i.e., the temperature of the thermostat. Presented results might be useful for energy conversion devices, efficient cryogenic radiative insulators engineering, and thermal logical circuits’ development.

  2. Analytical method for thermal stress analysis of plasma facing materials

    Science.gov (United States)

    You, J. H.; Bolt, H.

    2001-10-01

    The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed.

  3. Analytical method for thermal stress analysis of plasma facing materials

    International Nuclear Information System (INIS)

    You, J.H.; Bolt, H.

    2001-01-01

    The thermo-mechanical response of plasma facing materials (PFMs) to heat loads from the fusion plasma is one of the crucial issues in fusion technology. In this work, a fully analytical description of the thermal stress distribution in armour tiles of plasma facing components is presented which is expected to occur under typical high heat flux (HHF) loads. The method of stress superposition is applied considering the temperature gradient and thermal expansion mismatch. Several combinations of PFMs and heat sink metals are analysed and compared. In the framework of the present theoretical model, plastic flow and the effect of residual stress can be quantitatively assessed. Possible failure features are discussed

  4. Effective thermal conductivity in thermoelectric materials

    Energy Technology Data Exchange (ETDEWEB)

    Baranowski, LL; Snyder, GJ; Toberer, ES

    2013-05-28

    Thermoelectric generators (TEGs) are solid state heat engines that generate electricity from a temperature gradient. Optimizing these devices for maximum power production can be difficult due to the many heat transport mechanisms occurring simultaneously within the TEG. In this paper, we develop a model for heat transport in thermoelectric materials in which an "effective thermal conductivity" (kappa(eff)) encompasses both the one dimensional steady-state Fourier conduction and the heat generation/consumption due to secondary thermoelectric effects. This model is especially powerful in that the value of kappa(eff) does not depend upon the operating conditions of the TEG but rather on the transport properties of the TE materials themselves. We analyze a variety of thermoelectric materials and generator designs using this concept and demonstrate that kappa(eff) predicts the heat fluxes within these devices to 5% of the exact value. (C) 2013 AIP Publishing LLC.

  5. Phase Change Material Thermal Power Generator

    Science.gov (United States)

    Jones, Jack A. (Inventor); Chao, Yi (Inventor); Valdez, Thomas I. (Inventor)

    2014-01-01

    An energy producing device, for example a submersible vehicle for descending or ascending to different depths within water or ocean, is disclosed. The vehicle comprises a temperature-responsive material to which a hydraulic fluid is associated. A pressurized storage compartment stores the fluid as soon as the temperature-responsive material changes density. The storage compartment is connected with a hydraulic motor, and a valve allows fluid passage from the storage compartment to the hydraulic motor. An energy storage component, e.g. a battery, is connected with the hydraulic motor and is charged by the hydraulic motor when the hydraulic fluid passes through the hydraulic motor. Upon passage in the hydraulic motor, the fluid is stored in a further storage compartment and is then sent back to the area of the temperature-responsive material.

  6. Thermal testing transport packages for radioactive materials: Reality vs regulation

    International Nuclear Information System (INIS)

    Hovingh, J.; Carlson, R.W.

    1994-03-01

    The principle objective of this paper is to provide information that will help describe the physical thermal tests performed to demonstrate compliance with the hypothetical accident conditions specified in 10 CFR 71.73. Physical testing should be applied to packages that cannot be modeled by analysis to adequately predict their response to hypothetical accident conditions. These tests should be used when chemical decomposition or material changes occur during an accident that would be difficult to analytically predict or model

  7. Composite materials for thermal energy storage

    Science.gov (United States)

    Benson, D. K.; Burrows, R. W.; Shinton, Y. D.

    1985-01-01

    A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations are discussed. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

  8. Composite materials for thermal energy storage

    Science.gov (United States)

    Benson, D.K.; Burrows, R.W.; Shinton, Y.D.

    1985-01-04

    A composite material for thermal energy storage based upon polyhydric alcohols, such as pentaerythritol, trimethylol ethane (also known as pentaglycerine), neopentyl glycol and related compounds including trimethylol propane, monoaminopentaerythritol, diamino-pentaerythritol and tris(hydroxymethyl)acetic acid, separately or in combinations, which provide reversible heat storage through crystalline phase transformations. These PCM's do not become liquid during use and are in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, porous rock, and mixtures thereof. Particulate additions such as aluminum or graphite powders, as well as metal and carbon fibers can also be incorporated therein. Particulate and/or fibrous additions can be introduced into molten phase change materials which can then be cast into various shapes. After the phase change materials have solidified, the additions will remain dispersed throughout the matrix of the cast solid. The polyol is in contact with at least one material selected from the group consisting of metals, carbon, siliceous, plastic, cellulosic, natural fiber, artificial fiber, concrete, gypsum, and mixtures thereof.

  9. Optical-Thermal Response of Laser-Irradiated Tissue

    CERN Document Server

    Welch, Ashley J

    2011-01-01

    The second edition of 'Optical-Thermal Response of Laser-Irradiated Tissue' maintains the standard of excellence established in the first edition, while adjusting the content to reflect changes in tissue optics and medical applications since 1995. The material concerning light propagation now contains new chapters devoted to electromagnetic theory for coherent light. The material concerning thermal laser-tissue interactions contains a new chapter on pulse ablation of tissue. The medical applications section now includes several new chapters on Optical Coherent Tomography, acoustic imaging, molecular imaging, forensic optics and nerve stimulation. A detailed overview is provided of the optical and thermal response of tissue to laser irradiation along with diagnostic and therapeutic examples including fiber optics. Sufficient theory is included in the book so that it is suitable for a one or two semester graduate or for senior elective courses. Material covered includes: 1. light propagation and diagnostic appl...

  10. Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

    OpenAIRE

    Fei-Ran Shen; Hao Kuang; Feng-Xia Hu; Hui Wu; Qing-Zhen Huang; Fei-Xiang Liang; Kai-Ming Qiao; Jia Li; Jing Wang; Yao Liu; Lei Zhang; Min He; Ying Zhang; Wen-Liang Zuo; Ji-Rong Sun

    2017-01-01

    Materials with zero thermal expansion (ZTE) or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE) materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn–Co–Ge–In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE o...

  11. Thermal properties of composite materials with a complex fractal structure

    International Nuclear Information System (INIS)

    Cervantes-Álvarez, F; Reyes-Salgado, J J; Dossetti, V; Carrillo, J L

    2014-01-01

    In this work, we report the thermal characterization of platelike composite samples made of polyester resin and magnetite inclusions. By means of photoacoustic spectroscopy and thermal relaxation, the thermal diffusivity, conductivity and volumetric heat capacity of the samples were experimentally measured. The volume fraction of the inclusions was systematically varied in order to study the changes in the effective thermal conductivity of the composites. For some samples, a static magnetic field was applied during the polymerization process, resulting in anisotropic inclusion distributions. Our results show a decrease in the thermal conductivity of some of the anisotropic samples, compared to the isotropic randomly distributed ones. Our analysis indicates that the development of elongated inclusion structures leads to the formation of magnetite and resin domains, causing this effect. We correlate the complexity of the inclusion structure with the observed thermal response through a multifractal and lacunarity analysis. All the experimental data are contrasted with the well known Maxwell–Garnett effective media approximation for composite materials. (paper)

  12. Negative thermal expansion materials: technological key for control of thermal expansion.

    Science.gov (United States)

    Takenaka, Koshi

    2012-02-01

    Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over -30 ppm K -1 . Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.

  13. Negative thermal expansion materials: technological key for control of thermal expansion

    Directory of Open Access Journals (Sweden)

    Koshi Takenaka

    2012-01-01

    Full Text Available Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K−1. Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade.

  14. Negative thermal expansion materials: technological key for control of thermal expansion

    International Nuclear Information System (INIS)

    Takenaka, Koshi

    2012-01-01

    Most materials expand upon heating. However, although rare, some materials contract upon heating. Such negative thermal expansion (NTE) materials have enormous industrial merit because they can control the thermal expansion of materials. Recent progress in materials research enables us to obtain materials exhibiting negative coefficients of linear thermal expansion over −30 ppm K −1 . Such giant NTE is opening a new phase of control of thermal expansion in composites. Specifically examining practical aspects, this review briefly summarizes materials and mechanisms of NTE as well as composites containing NTE materials, based mainly on activities of the last decade. (topical review)

  15. A simple method for estimating thermal response of building ...

    African Journals Online (AJOL)

    This paper develops a simple method for estimating the thermal response of building materials in the tropical climatic zone using the basic heat equation. The efficacy of the developed model has been tested with data from three West African cities, namely Kano (lat. 12.1 ºN) Nigeria, Ibadan (lat. 7.4 ºN) Nigeria and Cotonou ...

  16. Reactive thermal waves in energetic materials

    Energy Technology Data Exchange (ETDEWEB)

    Hill, Larry G [Los Alamos National Laboratory

    2009-01-01

    Reactive thermal waves (RTWs) arise in several energetic material applications, including self-propagating high-temperature synthesis (SHS), high explosive cookoff, and the detonation of heterogeneous explosives. In this paper I exmaine ideal RTWs, by which I mean that (1) material motion is neglected, (2) the state dependence of reaction is Arrhenius in the temperature, and (3) the reaction rate is modulated by an arbitrary mass-fraction-based reaction progress function. Numerical simulations demonstrate that one's natural intuition, which is based mainly upon experience with inert materials and which leads one to expect diffusion processes to become relatively slow after a short time period, is invalid for high energy, state-sensitive reactive systems. Instead, theory predicts that RTWs can propagate at very high speeds. This result agrees with estimates for detonating heterogeneous explosives, which indicate that RTWs must spread from hot-spot nucleation sites at rates comparable to the detonation speed in order to produce experimentally-observed reaction zone thicknesses. Using dimensionless scaling and further invoking the high activation energy approximation, I obtain an analytic formula for the steady plane RTW speed from numerical calculations. I then compute the RTW speed for real explosives, and discuss aspects of their behavior.

  17. Pressure measurement using thermal properties of materials

    International Nuclear Information System (INIS)

    Cruz Pessoa, Jose Dalton; Calbo, Adonai Gimenes

    2004-01-01

    This work presents a design and two methods, one isothermal and one isovolumetric, for pressure measurements based on the compressibility coefficient (κ) and thermal expansibility (α) of the fluid under test. The setup and relevant construction details are described. To demonstrate the applicability of the isovolumetric measurement method, the setup was calibrated with respect to a Bourdon-type manometer; the other isothermic method was analyzed to determine construction details that could realize resolution requirements. The authors determined the effect of ambient temperature on device operation and the time response of the isovolumetric method. The device can be used to estimate the compressibility of a fluid and, in addition, could become an alternative for direct plant cell turgor measurement

  18. Composite Materials for Thermal Energy Storage: Enhancing Performance through Microstructures

    Science.gov (United States)

    Ge, Zhiwei; Ye, Feng; Ding, Yulong

    2014-01-01

    Chemical incompatibility and low thermal conductivity issues of molten-salt-based thermal energy storage materials can be addressed by using microstructured composites. Using a eutectic mixture of lithium and sodium carbonates as molten salt, magnesium oxide as supporting material, and graphite as thermal conductivity enhancer, the microstructural development, chemical compatibility, thermal stability, thermal conductivity, and thermal energy storage performance of composite materials are investigated. The ceramic supporting material is essential for preventing salt leakage and hence provides a solution to the chemical incompatibility issue. The use of graphite gives a significant enhancement on the thermal conductivity of the composite. Analyses suggest that the experimentally observed microstructural development of the composite is associated with the wettability of the salt on the ceramic substrate and that on the thermal conduction enhancer. PMID:24591286

  19. Composite materials for thermal energy storage: enhancing performance through microstructures.

    Science.gov (United States)

    Ge, Zhiwei; Ye, Feng; Ding, Yulong

    2014-05-01

    Chemical incompatibility and low thermal conductivity issues of molten-salt-based thermal energy storage materials can be addressed by using microstructured composites. Using a eutectic mixture of lithium and sodium carbonates as molten salt, magnesium oxide as supporting material, and graphite as thermal conductivity enhancer, the microstructural development, chemical compatibility, thermal stability, thermal conductivity, and thermal energy storage performance of composite materials are investigated. The ceramic supporting material is essential for preventing salt leakage and hence provides a solution to the chemical incompatibility issue. The use of graphite gives a significant enhancement on the thermal conductivity of the composite. Analyses suggest that the experimentally observed microstructural development of the composite is associated with the wettability of the salt on the ceramic substrate and that on the thermal conduction enhancer. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Basic Thermal Parameters of Selected Foods and Food Raw Materials

    OpenAIRE

    Monika Božiková; Ľubomír Híreš; Michal Valach; Martin Malínek; Jan Mareček

    2017-01-01

    In general, processing and manipulation with foods and food raw materials have significant influence on their physical properties. The article is focused on thermophysical parameters measurement of selected foods and food raw materials. There were examined thermal conductivity and thermal diffusivity of selected materials. For detection of thermal parameters was used instrument Isomet 2104, which principle of measurement is based on transient methods. In text are presented summary results of ...

  1. Carbon nanotubes for thermal interface materials in microelectronic packaging

    Science.gov (United States)

    Lin, Wei

    , an in situ functionalization process has for the first time been demonstrated. The in situ functionalization renders the vertically aligned carbon nanotubes a proper chemical reactivity for forming chemical bonding with other substrate materials such as gold and silicon. 2. An ultrafast microwave annealing process has been developed to reduce the defect density in vertically aligned carbon nanotubes. Raman and thermogravimetric analyses have shown a distinct defect reduction in the CNTs annealed in microwave for 3 min. Fibers spun from the as-annealed CNTs, in comparison with those from the pristine CNTs, show increases of ˜35% and ˜65%, respectively, in tensile strength (˜0.8 GPa) and modulus (˜90 GPa) during tensile testing; an ˜20% improvement in electrical conductivity (˜80000 S m-1) was also reported. The mechanism of the microwave response of CNTs was discussed. Such a microwave annealing process has been extended to the preparation of reduced graphene oxide. 3. Based on the fundamental understanding of interfacial thermal transport and surface chemistry of metals and carbon nanotubes, two major transfer/assembling processes have been developed: molecular bonding and metal bonding. Effective improvement of the interfacial thermal transport has been achieved by the interfacial bonding. 4. The thermal diffusivity of vertically aligned carbon nanotube (VACNT, multi-walled) films was measured by a laser flash technique, and shown to be ˜30 mm2 s-1 along the tube-alignment direction. The calculated thermal conductivities of the VACNT film and the individual CNTs are ˜27 and ˜540 W m-1 K-1, respectively. The technique was verified to be reliable although a proper sampling procedure is critical. A systematic parametric study of the effects of defects, buckling, tip-to-tip contacts, packing density, and tube-tube interaction on the thermal diffusivity was carried out. Defects and buckling decreased the thermal diffusivity dramatically. An increased packing

  2. Elastic response of thermal spray deposits under indentation tests

    International Nuclear Information System (INIS)

    Leigh, S.H.; Lin, C.K.; Berndt, C.C.

    1997-01-01

    The elastic response behavior of thermal spray deposits at Knoop indentations has been investigated using indentation techniques. The ration of hardness to elastic modulus, which is an important prerequisite for the evaluation of indentation fracture toughness, is determined by measuring the elastic recovery of the in-surface dimensions of Knoop indentations. The elastic moduli of thermal spray deposits are in the range of 12%--78% of the comparable bulk materials and reveal the anisotropic behavior of thermal spray deposits. A variety of thermal spray deposits has been examined, including Al 2 O 3 , yttria-stabilized ZrO 2 (YSZ), and NiAl. Statistical tools have been used to evaluate the error estimates of the data

  3. Adaptive Responses to Thermal Stress in Mammals

    Directory of Open Access Journals (Sweden)

    Yasser Lenis Sanin

    2015-12-01

    Full Text Available The environment animals have to cope with is a combination of natural factors such as temperature. Extreme changes in these factors can alter homeostasis, which can lead to thermal stress. This stress can be due to either high temperatures or low temperatures. Energy transference for thermoregulation in homoeothermic animals occurs through several mechanisms: conduction, convection, radiation and evaporation. When animals are subjected to thermal stress, physiological mechanisms are activated which may include endocrine, neuroendocrine and behavioral responses. Activation of the neuroendocrine system affects the secretion of hormones and neurotransmitters which act collectively as response mechanisms that allow them to adapt to stress. Mechanisms which have developed through evolution to allow animals to adapt to high environmental temperatures and to achieve thermo tolerance include physiological and physical changes in order to reduce food intake and metabolic heat production, to increase surface area of skin to dissipate heat, to increase blood flow to take heat from the body core to the skin and extremities to dissipate the heat, to increase numbers and activity of sweat glands, panting, water intake and color adaptation of integument system to reflect heat. Chronic exposure to thermal stress can cause disease, reduce growth, decrease productive and reproductive performance and, in extreme cases, lead to death. This paper aims to briefly explain the physical and physiological responses of mammals to thermal stress, like a tool for biological environment adaptation, emphasizing knowledge gaps and offering some recommendations to stress control for the animal production system.

  4. Flexible composite material with phase change thermal storage

    Science.gov (United States)

    Buckley, Theresa M. (Inventor)

    2001-01-01

    A highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The composite material can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The composite may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the PCM composite also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, ,gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  5. Basic Thermal Parameters of Selected Foods and Food Raw Materials

    Directory of Open Access Journals (Sweden)

    Monika Božiková

    2017-01-01

    Full Text Available In general, processing and manipulation with foods and food raw materials have significant influence on their physical properties. The article is focused on thermophysical parameters measurement of selected foods and food raw materials. There were examined thermal conductivity and thermal diffusivity of selected materials. For detection of thermal parameters was used instrument Isomet 2104, which principle of measurement is based on transient methods. In text are presented summary results of thermal parameters measurement for various foods and food raw materials as: granular materials – corn flour and wheat flour; fruits, vegetables and fruit products – grated apple, dried apple and apple juice; liquid materials – milk, beer etc. Measurements were performed in two temperature ranges according to the character of examined material. From graphical relations of thermophysical parameter is evident, that thermal conductivity and diffusivity increases with temperature and moisture content linearly, only for granular materials were obtained non‑linear dependencies. Results shows, that foods and food raw materials have different thermal properties, which are influenced by their type, structure, chemical and physical properties. From presented results is evident, that basic thermal parameters are important for material quality detection in food industry.

  6. Thermally emissive sensing materials for chemical spectroscopy analysis

    Science.gov (United States)

    Poole, Zsolt; Ohodnicki, Paul R.

    2018-05-08

    A sensor using thermally emissive materials for chemical spectroscopy analysis includes an emissive material, wherein the emissive material includes the thermally emissive materials which emit electromagnetic radiation, wherein the electromagnetic radiation is modified due to chemical composition in an environment; and a detector adapted to detect the electromagnetic radiation, wherein the electromagnetic radiation is indicative of the chemical interaction changes and hence chemical composition and/or chemical composition changes of the environment. The emissive material can be utilized with an optical fiber sensor, with the optical fiber sensor operating without the emissive material probed with a light source external to the material.

  7. Thermal conductivity analysis and applications of nanocellulose materials

    Science.gov (United States)

    Uetani, Kojiro; Hatori, Kimihito

    2017-01-01

    Abstract In this review, we summarize the recent progress in thermal conductivity analysis of nanocellulose materials called cellulose nanopapers, and compare them with polymeric materials, including neat polymers, composites, and traditional paper. It is important to individually measure the in-plane and through-plane heat-conducting properties of two-dimensional planar materials, so steady-state and non-equilibrium methods, in particular the laser spot periodic heating radiation thermometry method, are reviewed. The structural dependency of cellulose nanopaper on thermal conduction is described in terms of the crystallite size effect, fibre orientation, and interfacial thermal resistance between fibres and small pores. The novel applications of cellulose as thermally conductive transparent materials and thermal-guiding materials are also discussed. PMID:29152020

  8. Experiments on thermal conductivity in buffer materials for geologic repository

    International Nuclear Information System (INIS)

    Kanno, T.; Yano, T.; Wakamatsu, H.; Matsushima, E.

    1989-01-01

    Engineered barriers for geologic disposal for HLW are planned to consist of canister, overpack and buffer elements. One of important physical characteristics of buffer materials is determining temperature profiles within the near field in a repository. Buffer materials require high thermal conductivity to disperse radiogenic heat away to the host rock. As the buffer materials, compacted blocks of the mixture of sodium bentonite and sand have been the most promising candidate in some countries, e.g. Sweden, Switzerland and Japan. The authors have been carrying out a series of thermal dispersion experiments to evaluate thermal conductivity of bentonite/quartz sand blocks. In this study, the following two factors considered to affect thermal properties of the near field were examined: effective thermal conductivities of buffer materials, and heat transfer characteristics of the gap between overpack and buffer materials

  9. Phase change thermal control materials, method and apparatus

    Science.gov (United States)

    Buckley, Theresa M. (Inventor)

    2001-01-01

    An apparatus and method for metabolic cooling and insulation of a user in a cold environment. In its preferred embodiment the apparatus is a highly flexible composite material having a flexible matrix containing a phase change thermal storage material. The apparatus can be made to heat or cool the body or to act as a thermal buffer to protect the wearer from changing environmental conditions. The apparatus may also include an external thermal insulation layer and/or an internal thermal control layer to regulate the rate of heat exchange between the composite and the skin of the wearer. Other embodiments of the apparatus also provide 1) a path for evaporation or direct absorption of perspiration from the skin of the wearer for improved comfort and thermal control, 2) heat conductive pathways within the material for thermal equalization, 3) surface treatments for improved absorption or rejection of heat by the material, and 4) means for quickly regenerating the thermal storage capacity for reuse of the material. Applications of the composite materials are also described which take advantage of the composite's thermal characteristics. The examples described include a diver's wet suit, ski boot liners, thermal socks, gloves and a face mask for cold weather activities, and a metabolic heating or cooling blanket useful for treating hypothermia or fever patients in a medical setting and therapeutic heating or cooling orthopedic joint supports.

  10. Thermal energy storage using phase change materials fundamentals and applications

    CERN Document Server

    Fleischer, Amy S

    2015-01-01

    This book presents a comprehensive introduction to the use of solid‐liquid phase change materials to store significant amounts of energy in the latent heat of fusion. The proper selection of materials for different applications is covered in detail, as is the use of high conductivity additives to enhance thermal diffusivity. Dr. Fleischer explores how applications of PCMS have expanded over the past 10 years to include the development of high efficiency building materials to reduce heating and cooling needs, smart material design for clothing, portable electronic systems thermal management, solar thermal power plant design and many others. Additional future research directions and challenges are also discussed.

  11. Thermal Characterization of Nanostructures and Advanced Engineered Materials

    Science.gov (United States)

    Goyal, Vivek Kumar

    Continuous downscaling of Si complementary metal-oxide semiconductor (CMOS) technology and progress in high-power electronics demand more efficient heat removal techniques to handle the increasing power density and rising temperature of hot spots. For this reason, it is important to investigate thermal properties of materials at nanometer scale and identify materials with the extremely large or extremely low thermal conductivity for applications as heat spreaders or heat insulators in the next generation of integrated circuits. The thin films used in microelectronic and photonic devices need to have high thermal conductivity in order to transfer the dissipated power to heat sinks more effectively. On the other hand, thermoelectric devices call for materials or structures with low thermal conductivity because the performance of thermoelectric devices is determined by the figure of merit Z=S2sigma/K, where S is the Seebeck coefficient, K and sigma are the thermal and electrical conductivity, respectively. Nanostructured superlattices can have drastically reduced thermal conductivity as compared to their bulk counterparts making them promising candidates for high-efficiency thermoelectric materials. Other applications calling for thin films with low thermal conductivity value are high-temperature coatings for engines. Thus, materials with both high thermal conductivity and low thermal conductivity are technologically important. The increasing temperature of the hot spots in state-of-the-art chips stimulates the search for innovative methods for heat removal. One promising approach is to incorporate materials, which have high thermal conductivity into the chip design. Two suitable candidates for such applications are diamond and graphene. Another approach is to integrate the high-efficiency thermoelectric elements for on-spot cooling. In addition, there is strong motivation for improved thermal interface materials (TIMs) for heat transfer from the heat-generating chip

  12. Cryogenic Thermal Conductivity Measurements on Candidate Materials for Space Missions

    Science.gov (United States)

    Tuttle, JIm; Canavan, Ed; Jahromi, Amir

    2017-01-01

    Spacecraft and instruments on space missions are built using a wide variety of carefully-chosen materials. In addition to having mechanical properties appropriate for surviving the launch environment, these materials generally must have thermal conductivity values which meet specific requirements in their operating temperature ranges. Space missions commonly propose to include materials for which the thermal conductivity is not well known at cryogenic temperatures. We developed a test facility in 2004 at NASAs Goddard Space Flight Center to measure material thermal conductivity at temperatures between 4 and 300 Kelvin, and we have characterized many candidate materials since then. The measurement technique is not extremely complex, but proper care to details of the setup, data acquisition and data reduction is necessary for high precision and accuracy. We describe the thermal conductivity measurement process and present results for several materials.

  13. Material recognition based on thermal cues: Mechanisms and applications.

    Science.gov (United States)

    Ho, Hsin-Ni

    2018-01-01

    Some materials feel colder to the touch than others, and we can use this difference in perceived coldness for material recognition. This review focuses on the mechanisms underlying material recognition based on thermal cues. It provides an overview of the physical, perceptual, and cognitive processes involved in material recognition. It also describes engineering domains in which material recognition based on thermal cues have been applied. This includes haptic interfaces that seek to reproduce the sensations associated with contact in virtual environments and tactile sensors aim for automatic material recognition. The review concludes by considering the contributions of this line of research in both science and engineering.

  14. Study on the effect of shape-stabilized phase change materials on spacecraft thermal control in extreme thermal environment

    International Nuclear Information System (INIS)

    Wu, Wan-fan; Liu, Na; Cheng, Wen-long; Liu, Yi

    2013-01-01

    Highlights: ► A shape-stabilized PCM is used to protect the spacecraft attacked by high energy. ► Taking a satellite as example, it proves the solution given in the work is feasible. ► Low thermal conductivity makes the material above its thermal stability limit. ► It provides guidance on how to choose the shape-stabilized PCM for similar problems. - Abstract: In space, the emergencies such as short-term high heat flux is prone to cause spacecraft thermal control system faults, resulting in temperature anomalies of electronic equipment of the spacecraft and even failures in them. In order to protect the spacecraft attacked by the high energy, a new guard method is proposed. A shape-stabilized phase change material (PCM), which has high thermal conductivity and does not require being tightly packaged, is proposed to be used on the spacecraft. To prove the feasibility of using the material on spacecraft attacked by high energy, the thermal responses for spacecraft with shape-stabilized PCM are investigated in situations of normal and short-term high heat flux, in contrast to that with conventional thermal control system. The results indicate that the shape-stabilized PCM can effectively absorb the heat to prevent the thermal control system faults when the spacecraft’s outer heat flux changes dramatically and has no negative effect on spacecraft in normal heat flux. Additionally the effect of thermal conductivity of PCM on its application effectiveness is discussed

  15. Hazardous Materials Management and Emergency Response (HAMMER)

    Data.gov (United States)

    Federal Laboratory Consortium — The Volpentest Hazardous Materials Management and Emergency Response (HAMMER) Federal Training Center is a safety and emergency response training center that offers...

  16. Analysis of piping response to thermal and operational transients

    International Nuclear Information System (INIS)

    Wang, C.Y.

    1987-01-01

    The reactor piping system is an extremely complex three-dimensional structure. Maintaining its structural integrity is essential to the safe operation of the reactor and the steam-supply system. In the safety analysis, various transient loads can be imposed on the piping which may cause plastic deformation and possible damage to the system, including those generated from hydrodynamic wave propagations, thermal and operational transients, as well as the seismic events. At Argonne National Laboratory (ANL), a three-dimensional (3-D) piping code, SHAPS, aimed for short-duration transients due to wave propagation, has been developed. Since 1984, the development work has been shifted to the long-duration accidents originating from the thermal and operational transient. As a result, a new version of the code, SHAPS-2, is being established. This paper describes many features related to this later development. To analyze piping response generated from thermal and operational transients, a 3-D implicit finite element algorithm has been developed for calculating the hoop, flexural, axial, and torsional deformations induced by the thermomechanical loads. The analysis appropriately accounts for stresses arising from the temperature dependence of the elastic material properties, the thermal expansion of the materials, and the changes in the temperature-dependent yield surface. Thermal softening, failure, strain rate, creep, and stress ratching can also be considered

  17. Analysis of carbon based materials under fusion relevant thermal loads

    International Nuclear Information System (INIS)

    Compan, Jeremie Saint-Helene

    2008-01-01

    how anisotropy can be tailored and on the strategies which were applied for the production of the investigated materials. Textures of fibers and microstructures of matrices were also described. Thermo-physical properties such as thermal conductivity and thermal expansion of some CFCs were studied for different materials' orientations. For the first time, some off-axis results of thermal conductivity and thermal expansion for fusion related CFCs are displayed. Room temperature bending and tensile loading of CFCs were performed and they allowed relating the microstructural findings to the anisotropic mechanical response. Fiber architecture of CFCs and interfacial shear strength between the fiber and the matrix appeared to be the main parameters which dictate the fracture mechanisms. In addition, the analysis of five batches of one CFC permitted to understand the difficulty of reproducing such advanced material. The differences in terms of needling process were related to the variations of the tensile properties in the various fibrous directions. Finally, fusion-relevant transient heat loads were simulated on the investigated CBMs within various high heat flux facilities, i.e. electron beam, ion beam and plasma gun. Erosion scenarios at different scales were compiled in relation to the CBM properties but also the type of the transient event. The locally preferential erosion and ejection of material from the surface of the CBM are comprehensively described as well as their implications. This ejection of hot particles from the CBM surface (so-called Brittle Destruction (BD) mechanism) was defined, explained and analyzed. An experimental thermal shock resistance criterion based on thermal-shock induced weight loss is presented. After analyzing the anisotropic response of CFCs to transient heat loads in their three orthotropic fiber directions, attempts to reduce BD were done by loading them under off-axis orientations. It partly succeeded and led to the observation of

  18. Process for fabricating composite material having high thermal conductivity

    Science.gov (United States)

    Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

    2001-01-01

    A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

  19. Thermal stresses in hexagonal materials - heat treatment influence on their mechanical behaviour

    International Nuclear Information System (INIS)

    Gloaguen, D.; Freour, S.; Guillen, R.; Royer, J.; Francois, M.

    2004-01-01

    Internal stresses due to anisotropic thermal and plastic properties were investigated in rolled zirconium and titanium. The thermal stresses induced by a cooling process were predicted using a self-consistent model and compared with experimental results obtained by X-ray diffraction. The study of the elastoplastic response during uniaxial loading was performed along the rolling and the transverse direction of the sheet, considering the influence of the texture and the thermal stresses on the mechanical behaviour. An approach in order to determine the thermal behaviour of phases embedded in two-phase materials is also presented. For zirconium, the residual stresses due to thermal anisotropy are rather important (equivalent to 35% of the yield stress) and consequently they play an important role on the elastoplastic transition contrary to titanium. The study of two-phase material shows the influence and the interaction of the second phase on the thermal behaviour in the studied phase

  20. Thermal Energetic Reactor with High Reproduction of Fission Materials

    Directory of Open Access Journals (Sweden)

    Vladimir M. Kotov

    2012-01-01

    On the base of thermal reactors with high fission materials reproduction world atomic power engineering development supplying higher power and requiring smaller speed of raw uranium mining, than in the variant with fast reactors, is possible.

  1. Advanced Thermal Interface Material Systems for Space Applications, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — The ultimate aim of proposed efforts are to develop innovative material and process (M increase thermal cycles before degradation and efforts to ensure ease of...

  2. Illusion thermal device based on material with constant anisotropic thermal conductivity for location camouflage

    Science.gov (United States)

    Hou, Quanwen; Zhao, Xiaopeng; Meng, Tong; Liu, Cunliang

    2016-09-01

    Thermal metamaterials and devices based on transformation thermodynamics often require materials with anisotropic and inhomogeneous thermal conductivities. In this study, still based on the concept of transformation thermodynamics, we designed a planar illusion thermal device, which can delocalize a heat source in the device such that the temperature profile outside the device appears to be produced by a virtual source at another position. This device can be constructed by only one kind of material with constant anisotropic thermal conductivity. The condition which should be satisfied by the device is provided, and the required anisotropic thermal conductivity is then deduced theoretically. This study may be useful for the designs of metamaterials or devices since materials with constant anisotropic parameters have great facility in fabrication. A prototype device has been fabricated based on a composite composed by two naturally occurring materials. The experimental results validate the effectiveness of the device.

  3. Advanced materials for thermal management of electronic packaging

    CERN Document Server

    Tong, Xingcun Colin

    2011-01-01

    The need for advanced thermal management materials in electronic packaging has been widely recognized as thermal challenges become barriers to the electronic industry's ability to provide continued improvements in device and system performance. With increased performance requirements for smaller, more capable, and more efficient electronic power devices, systems ranging from active electronically scanned radar arrays to web servers all require components that can dissipate heat efficiently. This requires that the materials have high capability of dissipating heat and maintaining compatibility

  4. Graphene-based filament material for thermal ionization

    Energy Technology Data Exchange (ETDEWEB)

    Hewitt, J. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Shick, C. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Siegfried, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-09-19

    The use of graphene oxide materials for thermal ionization mass spectrometry analysis of plutonium and uranium has been investigated. Filament made from graphene oxide slurries have been 3-D printed. A method for attaching these filaments to commercial thermal ionization post assemblies has been devised. Resistive heating of the graphene based filaments under high vacuum showed stable operation in excess of 4 hours. Plutonium ion production has been observed in an initial set of filaments spiked with the Pu 128 Certified Reference Material.

  5. Using thermal power plants waste for building materials

    Science.gov (United States)

    Feduik, R. S.; Smoliakov, A. K.; Timokhin, R. A.; Batarshin, V. O.; Yevdokimova, Yu G.

    2017-10-01

    The recycled use of thermal power plants (TPPs) wastes in the building materials production is formulated. The possibility of using of TPPs fly ash as part of the cement composite binder for concrete is assessed. The results of X-ray diffraction and differential thermal analysis as well as and materials photomicrographs are presented. It was revealed that the fly ash of TPPs of Russian Primorsky Krai is suitable for use as a filler in cement binding based on its chemical composition.

  6. Method and apparatus for implementing material thermal property measurement by flash thermal imaging

    Science.gov (United States)

    Sun, Jiangang

    2017-11-14

    A method and apparatus are provided for implementing measurement of material thermal properties including measurement of thermal effusivity of a coating and/or film or a bulk material of uniform property. The test apparatus includes an infrared camera, a data acquisition and processing computer coupled to the infrared camera for acquiring and processing thermal image data, a flash lamp providing an input of heat onto the surface of a two-layer sample with an enhanced optical filter covering the flash lamp attenuating an entire infrared wavelength range with a series of thermal images is taken of the surface of the two-layer sample.

  7. Instrument for Measuring Thermal Conductivity of Materials at Low Temperatures

    Science.gov (United States)

    Fesmire, James; Sass, Jared; Johnson, Wesley

    2010-01-01

    With the advance of polymer and other non-metallic material sciences, whole new series of polymeric materials and composites are being created. These materials are being optimized for many different applications including cryogenic and low-temperature industrial processes. Engineers need these data to perform detailed system designs and enable new design possibilities for improved control, reliability, and efficiency in specific applications. One main area of interest is cryogenic structural elements and fluid handling components and other parts, films, and coatings for low-temperature application. An important thermal property of these new materials is the apparent thermal conductivity (k-value).

  8. Switchable Shape Memory Alloys (SMA) Thermal Materials

    Data.gov (United States)

    National Aeronautics and Space Administration — Materials and systems are being designed and developed to meet complex operational requirements while being kept lightweight, efficient, and robust. Multifunctional...

  9. Voltage tunability of thermal conductivity in ferroelectric materials

    Science.gov (United States)

    Ihlefeld, Jon; Hopkins, Patrick Edward

    2016-02-09

    A method to control thermal energy transport uses mobile coherent interfaces in nanoscale ferroelectric films to scatter phonons. The thermal conductivity can be actively tuned, simply by applying an electrical potential across the ferroelectric material and thereby altering the density of these coherent boundaries to directly impact thermal transport at room temperature and above. The invention eliminates the necessity of using moving components or poor efficiency methods to control heat transfer, enabling a means of thermal energy control at the micro- and nano-scales.

  10. Seal assembly for materials with different coefficients of thermal expansion

    Science.gov (United States)

    Minford, Eric [Laurys Station, PA

    2009-09-01

    Seal assembly comprising (a) two or more seal elements, each element having having a coefficient of thermal expansion; and (b) a clamping element having a first segment, a second segment, and a connecting segment between and attached to the first and second segments, wherein the two or more seal elements are disposed between the first and second segments of the clamping element. The connecting segment has a central portion extending between the first segment of the clamping element and the second segment of the clamping element, and the connecting segment is made of a material having a coefficient of thermal expansion. The coefficient of thermal expansion of the material of the connecting segment is intermediate the largest and smallest of the coefficients of thermal expansion of the materials of the two or more seal elements.

  11. Gas-thermal coating of powdered materials. Communication 2

    International Nuclear Information System (INIS)

    Ermakov, S.S.

    1986-01-01

    This paper investigates the microstructure, microhardness, chemical composition of the transition zone, and also the strength characteristics of gas-thermal coatings including their adhesive power to the substrate (iron brand NC 100.24) and the residual stresses in the coatings. The microstructure of the transition zone was investigated; it was established that on the side of the substrate its density is greater than the mean density of both types of coating. It is shown that the porosity of the substrate has a competing effect on the thermal interaction of materials. Discovered regularities lead to the conclusion that the process of gas-thermal coating of powdered materials is more effective than when compact materials are coated; most effective is the combination of gas-thermal coating with processes of heat treatment of powder-metallurgy products

  12. Thermal Materials Drive Professional Apparel Line

    Science.gov (United States)

    2014-01-01

    Johnson Space Center investigated phase change materials (PCMs) to use in spacesuit gloves to help maintain comfortable temperatures. Years later, Boston-based Ministry of Supply developed a dress shirt that incorporated the NASA-derived PCMs, could wick away moisture, and also control odors and bacterial growth. Deemed Apollo, the shirt performs like active wear and is available in white and oxford blue.

  13. Thermal shock behaviour of mullite-cordierite refractory materials

    Czech Academy of Sciences Publication Activity Database

    Boccaccini, D. N.; Leonelli, C.; Romagnoli, M.; Pellacani, G. C.; Veronesi, P.; Dlouhý, Ivo; Boccaccini, A. R.

    2007-01-01

    Roč. 106, č. 3 (2007), s. 142-148 ISSN 1743-6753 R&D Projects: GA AV ČR IAA200410502 Institutional research plan: CEZ:AV0Z20410507 Keywords : refraktory materials * thermal shock * fracutre toughness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 1.074, year: 2007

  14. Numerical modeling of Thermal Response Tests in Energy Piles

    Science.gov (United States)

    Franco, A.; Toledo, M.; Moffat, R.; Herrera, P. A.

    2013-05-01

    Nowadays, thermal response tests (TRT) are used as the main tools for the evaluation of low enthalpy geothermal systems such as heat exchangers. The results of TRT are used for estimating thermal conductivity and thermal resistance values of those systems. We present results of synthetic TRT simulations that model the behavior observed in an experimental energy pile system, which was installed at the new building of the Faculty of Engineering of Universidad de Chile. Moreover, we also present a parametric study to identify the most influent parameters in the performance of this type of tests. The modeling was developed using the finite element software COMSOL Multiphysics, which allows the incorporation of flow and heat transport processes. The modeled system consists on a concrete pile with 1 m diameter and 28 m deep, which contains a 28 mm diameter PEX pipe arranged in a closed circuit. Three configurations were analyzed: a U pipe, a triple U and a helicoid shape implemented at the experimental site. All simulations were run considering transient response in a three-dimensional domain. The simulation results provided the temperature distribution on the pile for a set of different geometry and physical properties of the materials. These results were compared with analytical solutions which are commonly used to interpret TRT data. This analysis demonstrated that there are several parameters that affect the system response in a synthetic TRT. For example, the diameter of the simulated pile affects the estimated effective thermal conductivity of the system. Moreover, the simulation results show that the estimated thermal conductivity for a 1 m diameter pile did not stabilize even after 100 hours since the beginning of the test, when it reached a value 30% below value used to set up the material properties in the simulation. Furthermore, we observed different behaviors depending on the thermal properties of concrete and soil. According to the simulations, the thermal

  15. Handbook for Response to Suspect Radioactive Materials

    International Nuclear Information System (INIS)

    Cliff, William C.; Pappas, Richard A.; Arthur, Richard J.

    2005-01-01

    This document provides response actions to be performed following the initial port, airport, or border crossing discovery of material that is suspected of being radioactive. The purpose of this guide is to provide actions appropriate for handling radioactive material

  16. New flexible thermal control material for long-life satellite

    International Nuclear Information System (INIS)

    Sasaki, Shigekuni; Hasuda, Yoshinori; Ichino, Toshihiro

    1986-01-01

    Flexible thermal control materials are light weight, cheap and excellent in the practical applicability, and are expected to be applied to future long life, large capacity satellites. However, the flexible thermal control materials used at present have the defect that either the space environment withstanding capability or the thermal control performance is poor. Therefore, the authors examined the flexible thermal control materials which are excellent in both these properties, and have developed the thermal control material PEI-OSR using polyether imide films as the substrate. In this study, while comparing with the FEP Teflon with silver vapor deposition, which has been used so far for short life satellites, the long term reliability of the PEI-OSR supposing the use for seven years was examined. As the results, the FEP Teflon with silver vapor deposition caused cracking and separation by irradiation and heat cycle test, and became unusable, but the PEI-OSR did not change its flexibility at all. Also the thermal control performance of the PEI-OSR after the test equivalent to seven years was superior to the initial performance of the Kaptone with aluminum vapor deposition, which has excellent space environment endurance, thus it was clarified that the PEI-OSR is the most excellent for this purpose. (Kako, I.)

  17. Round robin testing of thermal conductivity reference materials

    International Nuclear Information System (INIS)

    Hulstrom, L.C.; Tye, R.P.; Smith, S.E.

    1985-07-01

    The Basalt Waste Isolation Project (BWIP), operated by Rockwell Hanford Operations, has a need to determine the thermal properties of basalt in the region being considered for a nuclear waste repository in basalt. Experimental data on thermal conductivity and its variation with temperature are information required for the characterization of basalt. To establish thermal conductivity values for the reference materials, an interlaboratory measurements program was undertaken. The program was planned to meet the objectives of performing an experimental characterization of the new stock and providing a detailed analysis of the results such that reference values of thermal conductivity could be determined. This program of measurements of the thermal conductivity of Pyrex 7740 and Pyroceram 9606 has produced recommended values that are within +- 1% of those accepted previously. These measurements together with those of density indicate that the present lots of material are similar to those previously available. Pyrex 7740 and Pyroceram 9606 can continue to be used with confidence as thermal conductivity reference materials for studies on rocks and minerals and other materials of similar thermal conductivity. The uncertainty range for Pyrex 7740 and Pyroceram 9606 up to 300 0 C is +- 10.3% and +- 5.6%, respectively. This range is similar to that indicated for the previously recommended values proposed some 18 years ago. It would appear that the overall state of the art in thermal conductivity measurements for materials in this range has changed little in the intervening years. The above uncertainties, which would have been greater had not three data sets been eliminated, are greater than those which are normally claimed for each individual method. Analyses of these differences through refinements in techniques and additional measurements to higher temperatures are required. 13 refs., 7 figs., 4 tabs

  18. Thermal protection for hypervelocity flight in earth's atmosphere by use of radiation backscattering ablating materials

    Science.gov (United States)

    Howe, John T.; Yang, Lily

    1991-01-01

    A heat-shield-material response code predicting the transient performance of a material subject to the combined convective and radiative heating associated with the hypervelocity flight is developed. The code is dynamically interactive to the heating from a transient flow field, including the effects of material ablation on flow field behavior. It accomodates finite time variable material thickness, internal material phase change, wavelength-dependent radiative properties, and temperature-dependent thermal, physical, and radiative properties. The equations of radiative transfer are solved with the material and are coupled to the transfer energy equation containing the radiative flux divergence in addition to the usual energy terms.

  19. Porous materials produced from incineration ash using thermal plasma technology.

    Science.gov (United States)

    Yang, Sheng-Fu; Chiu, Wen-Tung; Wang, To-Mai; Chen, Ching-Ting; Tzeng, Chin-Ching

    2014-06-01

    This study presents a novel thermal plasma melting technique for neutralizing and recycling municipal solid waste incinerator (MSWI) ash residues. MSWI ash residues were converted into water-quenched vitrified slag using plasma vitrification, which is environmentally benign. Slag is adopted as a raw material in producing porous materials for architectural and decorative applications, eliminating the problem of its disposal. Porous materials are produced using water-quenched vitrified slag with Portland cement and foaming agent. The true density, bulk density, porosity and water absorption ratio of the foamed specimens are studied here by varying the size of the slag particles, the water-to-solid ratio, and the ratio of the weights of the core materials, including the water-quenched vitrified slag and cement. The thermal conductivity and flexural strength of porous panels are also determined. The experimental results show the bulk density and the porosity of the porous materials are 0.9-1.2 g cm(-3) and 50-60%, respectively, and the pore structure has a closed form. The thermal conductivity of the porous material is 0.1946 W m(-1) K(-1). Therefore, the slag composite materials are lightweight and thermal insulators having considerable potential for building applications. Copyright © 2013 Elsevier Ltd. All rights reserved.

  20. Negative thermal expansion in functional materials: controllable thermal expansion by chemical modifications.

    Science.gov (United States)

    Chen, Jun; Hu, Lei; Deng, Jinxia; Xing, Xianran

    2015-06-07

    Negative thermal expansion (NTE) is an intriguing physical property of solids, which is a consequence of a complex interplay among the lattice, phonons, and electrons. Interestingly, a large number of NTE materials have been found in various types of functional materials. In the last two decades good progress has been achieved to discover new phenomena and mechanisms of NTE. In the present review article, NTE is reviewed in functional materials of ferroelectrics, magnetics, multiferroics, superconductors, temperature-induced electron configuration change and so on. Zero thermal expansion (ZTE) of functional materials is emphasized due to the importance for practical applications. The NTE functional materials present a general physical picture to reveal a strong coupling role between physical properties and NTE. There is a general nature of NTE for both ferroelectrics and magnetics, in which NTE is determined by either ferroelectric order or magnetic one. In NTE functional materials, a multi-way to control thermal expansion can be established through the coupling roles of ferroelectricity-NTE, magnetism-NTE, change of electron configuration-NTE, open-framework-NTE, and so on. Chemical modification has been proved to be an effective method to control thermal expansion. Finally, challenges and questions are discussed for the development of NTE materials. There remains a challenge to discover a "perfect" NTE material for each specific application for chemists. The future studies on NTE functional materials will definitely promote the development of NTE materials.

  1. Design of materials with extreme thermal expansion using a three-phase topology optimization method

    DEFF Research Database (Denmark)

    Sigmund, Ole; Torquato, S.

    1997-01-01

    Composites with extremal or unusual thermal expansion coefficients are designed using a three-phase topology optimization method. The composites are made of two different material phases and a void phase. The topology optimization method consists in finding the distribution of material phases...... materials having maximum directional thermal expansion (thermal actuators), zero isotropic thermal expansion, and negative isotropic thermal expansion. It is shown that materials with effective negative thermal expansion coefficients can be obtained by mixing two phases with positive thermal expansion...

  2. Chemical and thermal analysis for characterisation of building materials

    International Nuclear Information System (INIS)

    Kumar, S.C.; Sudersanan, M.; Ravindran, P.V.; Kalekar, B.B.; Mathur, P.K.

    2000-01-01

    Cement and other construction materials are extensively used for the construction of shielding materials for nuclear and high energy radiations. The design and optimum utilisation of such materials need an accurate analysis of their chemical composition. The moisture content and presence of bound water and other volatile materials are also important. The use of thermal analysis supplements the data obtained by chemical analysis and enables a distinction of moisture and chemically bound water. It also enables an identification of the process leading to the loss on ignition. The work carried out on the analysis of sand, cement and other aggregate materials used for the preparation of concrete is described in the paper. (author)

  3. Thermal properties and application of potential lithium silicate breeder materials

    International Nuclear Information System (INIS)

    Skokan, A.; Wedemeyer, H.; Vollath, D.; Gunther, E.

    1987-01-01

    Phase relations, thermal stability and preparation methods of the Li 2 O-rich silicates Li 8 SiO 6 and ''Li 6 SiO 5 '' have been investigated experimentally, the application of these compounds as solid breeder materials is discussed. In the second part of this contribution, the results of thermal expansion measurements on the silicates Li 2 SiO 3 , Li 4 SiO 4 and Li 8 SiO 6 are presented

  4. Thermal properties and application of potential lithium silicate breeder materials

    International Nuclear Information System (INIS)

    Skokan, A.; Wedemeyer, H.; Vollath, D.; Guenther, E.

    1986-01-01

    Phase relations, thermal stability and preparation methods of the Li 2 O-rich silicates Li 8 SiO 6 and 'Li 6 SiO 5 ' have been investigated experimentally, the application of these compounds as solid breeder materials is discussed. In the second part of this contribution, the results of thermal expansion measurements on the silicates Li 2 SiO 3 , Li 4 SiO 4 and Li 8 SiO 6 are presented. (author)

  5. Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

    Science.gov (United States)

    Shen, Fei-Ran; Kuang, Hao; Hu, Feng-Xia; Wu, Hui; Huang, Qing-Zhen; Liang, Fei-Xiang; Qiao, Kai-Ming; Li, Jia; Wang, Jing; Liu, Yao; Zhang, Lei; He, Min; Zhang, Ying; Zuo, Wen-Liang; Sun, Ji-Rong; Shen, Bao-Gen

    2017-10-01

    Materials with zero thermal expansion (ZTE) or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE) materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn-Co-Ge-In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE owing to a martensitic magnetostructural transition. The major finding is that the thermal expansion behavior can be totally controlled by modulating the crystallinity degree and phase transition from atomic scale. Self-compensation effect leads to ultra-low thermal expansion with a linear expansion coefficient as small as +0.68 × 10-6/K over a wide temperature range around room temperature. The present study opens an avenue to reach ZTE particularly from the large class of giant NTE materials based on phase transition.

  6. Ultra-low thermal expansion realized in giant negative thermal expansion materials through self-compensation

    Directory of Open Access Journals (Sweden)

    Fei-Ran Shen

    2017-10-01

    Full Text Available Materials with zero thermal expansion (ZTE or precisely tailored thermal expansion are in urgent demand of modern industries. However, the overwhelming majority of materials show positive thermal expansion. To develop ZTE or negative thermal expansion (NTE materials as compensators has become an important challenge. Here, we present the evidence for the realization of ultra-low thermal expansion in Mn–Co–Ge–In particles. The bulk with the Ni2In-type hexagonal structure undergoes giant NTE owing to a martensitic magnetostructural transition. The major finding is that the thermal expansion behavior can be totally controlled by modulating the crystallinity degree and phase transition from atomic scale. Self-compensation effect leads to ultra-low thermal expansion with a linear expansion coefficient as small as +0.68 × 10−6/K over a wide temperature range around room temperature. The present study opens an avenue to reach ZTE particularly from the large class of giant NTE materials based on phase transition.

  7. Thermal energy storage based on cementitious materials: A review

    Directory of Open Access Journals (Sweden)

    Khadim Ndiaye

    2018-01-01

    Full Text Available Renewable energy storage is now essential to enhance the energy performance of buildings and to reduce their environmental impact. Many heat storage materials can be used in the building sector in order to avoid the phase shift between solar radiation and thermal energy demand. However, the use of storage material in the building sector is hampered by problems of investment cost, space requirements, mechanical performance, material stability, and high storage temperature. Cementitious material is increasingly being used as a heat storage material thanks to its low price, mechanical performance and low storage temperature (generally lower than 100 °C. In addition, cementitious materials for heat storage have the prominent advantage of being easy to incorporate into the building landscape as self-supporting structures or even supporting structures (walls, floor, etc.. Concrete solutions for thermal energy storage are usually based on sensible heat transfer and thermal inertia. Phase Change Materials (PCM incorporated in concrete wall have been widely investigated in the aim of improving building energy performance. Cementitious material with high ettringite content stores heat by a combination of physical (adsorption and chemical (chemical reaction processes usable in both the short (daily, weekly and long (seasonal term. Ettringite materials have the advantage of high energy storage density at low temperature (around 60 °C. The encouraging experimental results in the literature on heat storage using cementitious materials suggest that they could be attractive in a number of applications. This paper summarizes the investigation and analysis of the available thermal energy storage systems using cementitious materials for use in various applications.

  8. Thermally joining and/or coating or thermally separating the workpieces having heat-sensitive coating, comprises restoring coating by thermally coating the coating material after thermally joining and/or coating or thermally separating

    OpenAIRE

    Riedel, Frank; Winkelmann, Ralf; Puschmann, Markus

    2011-01-01

    The method for thermally joining and/or coating or thermally separating the workpieces (1), which have a heat-sensitive coating (2), comprises restoring the coating by thermally coating a coating material (3) after thermally joining and/or coating or thermally separating the workpieces. A part of the thermal energy introduced in the workpiece for joining and/or coating or separating or in the workpieces is used for thermally coating the coating material. Two workpieces are welded or soldered ...

  9. Physiological Responses to Thermal Stress and Exercise

    Science.gov (United States)

    Iyota, Hiroyuki; Ohya, Akira; Yamagata, Junko; Suzuki, Takashi; Miyagawa, Toshiaki; Kawabata, Takashi

    The simple and noninvasive measuring methods of bioinstrumentation in humans is required for optimization of air conditioning and management of thermal environments, taking into consideration the individual specificity of the human body as well as the stress conditions affecting each. Changes in human blood circulation were induced with environmental factors such as heat, cold, exercise, mental stress, and so on. In this study, the physiological responses of human body to heat stress and exercise were investigated in the initial phase of the developmental research. We measured the body core and skin temperatures, skin blood flow, and pulse wave as the indices of the adaptation of the cardiovascular system. A laser Doppler skin blood flowmetry using an optical-sensor with a small portable data logger was employed for the measurement. These results reveal the heat-stress and exercise-induced circulatory responses, which are under the control of the sympathetic nerve system. Furthermore, it was suggested that the activity of the sympathetic nervous system could be evaluated from the signals of the pulse wave included in the signals derived from skin blood flow by means of heart rate variability assessments and detecting peak heights of velocity-plethysmogram.

  10. Thermal analysis of charring materials based on pyrolysis interface model

    Directory of Open Access Journals (Sweden)

    Huang Hai-Ming

    2014-01-01

    Full Text Available Charring thermal protection systems have been used to protect hypersonic vehicles from high heat loads. The pyrolysis of charring materials is a complicated physical and chemical phenomenon. Based on the pyrolysis interface model, a simulating approach for charring ablation has been designed in order to obtain one dimensional transient thermal behavior of homogeneous charring materials in reentry capsules. As the numerical results indicate, the pyrolysis rate and the surface temperature under a given heat flux rise abruptly in the beginning, then reach a plateau, but the temperature at the bottom rises very slowly to prevent the structural materials from being heated seriously. Pyrolysis mechanism can play an important role in thermal protection systems subjected to serious aerodynamic heat.

  11. XRD Investigation of Some Thermal Degraded Starch Based Materials

    Directory of Open Access Journals (Sweden)

    Mihai Todica

    2016-01-01

    Full Text Available The thermal degradation of some starch based materials was investigated using XRD method. The samples were obtained by thermal extrusion of mixtures of different proportions of starch, glycerol, and water. Such materials are suitable for the manufacturing of low pollutant packaging. Thermal degradation is one of the simplest ways to destroy such materials and this process is followed by structural modification of the local ordering of samples, water evaporation, crystallization, oxidation, or destruction of the chemical bonds. These modifications need to be studied in order to reduce to the minimum production of pollutant residues by burning process. XRD measurements show modification of the local ordering of the starch molecules depending on the temperature and initial composition of the samples. The molecular ordering perturbation is more pronounced in samples with low content of starch.

  12. Responsible stewardship of nuclear materials

    International Nuclear Information System (INIS)

    Hannum, W.H.

    1994-01-01

    The ability to tap the massive energy potential of nuclear fission was first developed as a weapon to end a terrible world war. Nuclear fission is also a virtually inexhaustible energy resource, and is the only energy supply in certain areas in Russia, Kazakhstan and elsewhere. The potential link between civilian and military applications has been and continues to be a source of concern. With the end of the Cold War, this issue has taken a dramatic turn. The U.S. and Russia have agreed to reduce their nuclear weapons stockpiles by as much as two-thirds. This will make some 100 tonnes of separated plutonium and 500 tonnes of highly enriched uranium available, in a form that is obviously directly usable for weapons. The total world inventory of plutonium is now around 1000 tonnes and is increasing at 60-70 tonnes per year. There is even more highly enriched uranium. Fortunately the correct answer to what to do with excess weapons material is also the most attractive. It should be used and reused as fuel for fast reactors. Material in use (particularly nuclear material) is very easy to monitor and control, and is quite unattractive for diversion. Active management of fissile materials not only makes a major contribution to economic stability and well-being, but also simplifies accountability, inspection and other safeguards processes; provides a revenue stream to pay for the necessary safeguards; and, most importantly, limits the prospective world inventory of plutonium to only that which is used and useful

  13. Thermal interface material characterization for cryogenic electronic packaging solutions

    Science.gov (United States)

    Dillon, A.; McCusker, K.; Van Dyke, J.; Isler, B.; Christiansen, M.

    2017-12-01

    As applications of superconducting logic technologies continue to grow, the need for efficient and reliable cryogenic packaging becomes crucial to development and testing. A trade study of materials was done to develop a practical understanding of the properties of interface materials around 4 K. While literature exists for varying interface tests, discrepancies are found in the reported performance of different materials and in the ranges of applied force in which they are optimal. In considering applications extending from top cooling a silicon chip to clamping a heat sink, a range of forces from approximately 44 N to approximately 445 N was chosen for testing different interface materials. For each range of forces a single material was identified to optimize the thermal conductance of the joint. Of the tested interfaces, indium foil clamped at approximately 445 N showed the highest thermal conductance. Results are presented from these characterizations and useful methodologies for efficient testing are defined.

  14. Stimuli-responsive liquid crystalline materials

    NARCIS (Netherlands)

    Debije, M.G.; Schenning, A.P.H.J.; Hashmi, Saleem

    2016-01-01

    Stimuli-responsive materials which respond to triggers from the environment by changing their properties are one of the focal points in materials science. For precise functional properties, well-defined hierarchically ordered supramolecular materials are crucial. The self-assembly of liquid crystals

  15. Response to Illicit Trafficking of Radioactive Materials

    International Nuclear Information System (INIS)

    2010-01-01

    Two response paths are discussed in the presentation. Reactive response follows when an alarm of a border monitor goes off or a notification is received about an incident involving or suspected to involve radioactive materials. The response can also be the result of the finding of a discrepancy between a customs declaration form and the corresponding actual shipment. Proactive response is undertaken upon receipt of intelligence information suggesting the illicit trafficking of radioactive materials, notification about the discovery of non-compliance with transport regulations or if discrepancies are found in an inventory of radioactive materials.

  16. Preparation, characterization, and thermal properties of microencapsulated phase change material for thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Alkan, Cemil; Sari, Ahmet; Karaipekli, Ali [Department of Chemistry, Gaziosmanpasa University, 60240 Tokat (Turkey); Uzun, Orhan [Department of Physics, Gaziosmanpasa University, 60240 Tokat (Turkey)

    2009-01-15

    This study is focused on the preparation, characterization, and determination of thermal properties of microencapsulated docosane with polymethylmethacrylate (PMMA) as phase change material for thermal energy storage. Microencapsulation of docosane has been carried out by emulsion polymerization. The microencapsulated phase change material (MEPCM) was characterized using scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. Thermal properties and thermal stability of MEPCM were measured by differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). DSC analysis indicated that the docosane in the microcapsules melts at 41.0 C and crystallizes at 40.6 C. It has latent heats of 54.6 and -48.7 J/g for melting and crystallization, respectively. TGA showed that the MEPCM degraded in three distinguishable steps and had good chemical stability. Accelerated thermal cycling tests also indicated that the MEPCM had good thermal reliability. Based on all these results, it can be concluded that the microencapsulated docosane as MEPCMs have good potential for thermal energy storage purposes such as solar space heating applications. (author)

  17. A new high power thermal battery cathode material

    International Nuclear Information System (INIS)

    Faul, I.

    1986-01-01

    Smaller and lighter thermal batteries are major aims of the battery research programme at RAE Farnborough. Modern designs of thermal batteries, for use as power supplies in weapon systems, almost invariably use the Li:molten salt:FeS/sub 2/ system because of the significant increase in energy density achieved in comparison with the earlier Ca/CaCrO/sub 4/ couple. The disadvantage of the FeS/sub 2/ system is that the working cell voltage, between 1.5 and 2.0 V, is significantly lower so leading to more cells per battery than the earlier system. Further work at RAE and MSA (Britain) Ltd showed that the poor thermal stability of TiS/sub 2/ limited its use in thermal batteries, whilst the more stable V/sub 6/O/sub 13/ oxidised the electrolyte, giving poor efficiencies. However, the resulting reduced vanadium oxide material, subsequently called lithiated vanadium oxide (LVO), was found to be an excellent high voltage thermal battery cathode, being the subject of both UK and US patents. In this study both V/sub 6/O/sub 13/ made by the direct stoichiometric reaction of V/sub 2/O/sub 5/ and V and also by thermal decomposition of NH/sub 4/VO/sub 3/ under argon, have been used with equal success as the starting material for the preparation of LVO

  18. Handbook on dielectric and thermal properties of microwaveable materials

    CERN Document Server

    Komarov, Vyacheslav V

    2012-01-01

    The application of microwave energy for thermal processing of different materials and substances is a rapidly growing trend in modern science and engineering. In fact, optimal design work involving microwaves is impossible without solid knowledge of the properties of these materials. Here s a practical reference that collects essential data on the dielectric and thermal properties of microwaveable materials, saving you countless hours on projects in a wide range of areas, including microwave design and heating, applied electrodynamics, food science, and medical technology. This unique book provides hard-to-find information on complex dielectric permittivity of media at industrial, scientific, and medical frequencies (430 MHz, 915MHz, 2.45GHz, 5.8 GHz, and 24.125GHz). Written by a leading expert in the field, this authoritative book does an exceptional job at presenting critical data on various materials and explaining what their key characteristics are concerning microwaves.

  19. Cellular and Porous Materials Thermal Properties Simulation and Prediction

    CERN Document Server

    Öchsner, Andreas; de Lemos, Marcelo J S

    2008-01-01

    Providing the reader with a solid understanding of the fundamentals as well as an awareness of recent advances in properties and applications of cellular and porous materials, this handbook and ready reference covers all important analytical and numerical methods for characterizing and predicting thermal properties. In so doing it directly addresses the special characteristics of foam-like and hole-riddled materials, combining theoretical and experimental aspects for characterization purposes.

  20. Rapid charging of thermal energy storage materials through plasmonic heating.

    Science.gov (United States)

    Wang, Zhongyong; Tao, Peng; Liu, Yang; Xu, Hao; Ye, Qinxian; Hu, Hang; Song, Chengyi; Chen, Zhaoping; Shang, Wen; Deng, Tao

    2014-09-01

    Direct collection, conversion and storage of solar radiation as thermal energy are crucial to the efficient utilization of renewable solar energy and the reduction of global carbon footprint. This work reports a facile approach for rapid and efficient charging of thermal energy storage materials by the instant and intense photothermal effect of uniformly distributed plasmonic nanoparticles. Upon illumination with both green laser light and sunlight, the prepared plasmonic nanocomposites with volumetric ppm level of filler concentration demonstrated a faster heating rate, a higher heating temperature and a larger heating area than the conventional thermal diffusion based approach. With controlled dispersion, we further demonstrated that the light-to-heat conversion and thermal storage properties of the plasmonic nanocomposites can be fine-tuned by engineering the composition of the nanocomposites.

  1. Novel Magnetic-to-Thermal Conversion and Thermal Energy Management Composite Phase Change Material

    Directory of Open Access Journals (Sweden)

    Xiaoqiao Fan

    2018-05-01

    Full Text Available Superparamagnetic materials have elicited increasing interest due to their high-efficiency magnetothermal conversion. However, it is difficult to effectively manage the magnetothermal energy due to the continuous magnetothermal effect at present. In this study, we designed and synthesized a novel Fe3O4/PEG/SiO2 composite phase change material (PCM that can simultaneously realize magnetic-to-thermal conversion and thermal energy management because of outstanding thermal energy storage ability of PCM. The composite was fabricated by in situ doping of superparamagnetic Fe3O4 nanoclusters through a simple sol–gel method. The synthesized Fe3O4/PEG/SiO2 PCM exhibited good thermal stability, high phase change enthalpy, and excellent shape-stabilized property. This study provides an additional promising route for application of the magnetothermal effect.

  2. Characterization of the heat transfer properties of thermal interface materials

    Science.gov (United States)

    Fullem, Travis Z.

    Physicists have studied the thermal conductivity of solids for decades. As a result of these efforts, thermal conduction in crystalline solids is well understood; there are detailed theories describing thermal conduction due to electrons and phonons. Phonon scattering and transmission at solid/solid interfaces, particularly above cryogenic temperatures, is not well understood and more work is needed in this area. The desire to solve engineering problems which require good thermal contact between mating surfaces has provided enhanced motivation for furthering the state of the art on this topic. Effective thermal management is an important design consideration in microelectronic systems. A common technique for removing excess heat from an electronic device is to attach a heatsink to the device; it is desirable to minimize the thermal resistance between the device and the heatsink. This can be accomplished by placing a thermal interface material (TIM) between the two surfaces. Due to the ever-increasing power densities found in electronic components, there is a desire to design better TIMs, which necessitates the ability to characterize TIM bondlines and to better understand the physics of heat conduction through TIM bondlines. A micro Fourier apparatus which employs Pt thin film thermometers of our design has been built and is capable of precisely quantifying the thermal resistance of thermal interface materials. In the present work several types of commercially available TIMs have been studied using this apparatus, including: greases, filled epoxies, and thermally conductive pads. In the case of filled epoxies, bondlines of various thicknesses, ranging from thirty microns to several hundred microns, have been measured. The microstructure of these bondlines has been investigated using optical microscopy and acoustic microscopy. Measured values of thermal conductivity are considered in terms of microstructural features such as percolation networks and filler particle

  3. Pattern-free thermal modulator via thermal radiation between Van der Waals materials

    Science.gov (United States)

    Liu, Xianglei; Shen, Jiadong; Xuan, Yimin

    2017-10-01

    Modulating heat flux provides a platform for a plethora of emerging devices such as thermal diodes, thermal transistors, and thermal memories. Here, a pattern-free noncontact thermal modulator is proposed based on the mechanical rotation between two Van der Waals films with optical axes parallel to the surfaces. A modulation contrast can reach a value higher than 5 for hexagonal Boron Nitride (hBN) films separated by a nanoscale gap distance. The dominant radiative heat exchange comes from the excitation of both Type I and Type II hyperbolic surface phonon polaritons (HSPhPs) at the vacuum-hBN interface for different orientations, while the large modulation contrast is mainly attributed to the mismatching Type I HSPhPs induced by rotation. This work opens the possibility to design cheap thermal modulators without relying on nanofabrication techniques, and paves the way to apply natural Van der Waals materials in manipulating heat currents in an active way.

  4. Thermal expansion model for multiphase electronic packaging materials

    International Nuclear Information System (INIS)

    Allred, B.E.; Warren, W.E.

    1991-01-01

    Control of thermal expansion is often necessary in the design and selection of electronic packages. In some instances, it is desirable to have a coefficient of thermal expansion intermediate between values readily attainable with single or two phase materials. The addition of a third phase in the form of fillers, whiskers, or fibers can be used to attain intermediate expansions. To help design the thermal expansion of multiphase materials for specific applications, a closed form model has been developed that accurately predicts the effective elastic properties of isotropic filled materials and transversely isotropic lamina. Properties of filled matrix materials are used as inputs to the lamina model to obtain the composite elastic properties as a function of the volume fraction of each phase. Hybrid composites with two or more fiber types are easily handled with this model. This paper reports that results for glass, quartz, and Kevlar fibers with beta-eucryptite filled polymer matrices show good agreement with experimental results for X, Y, and Z thermal expansion coefficients

  5. Investigation of thermal management materials for automotive electronic control units

    International Nuclear Information System (INIS)

    Mallik, Sabuj; Ekere, Ndy; Best, Chris; Bhatti, Raj

    2011-01-01

    Today's electronics packages are smaller and more powerful than ever before. This leads to ever increasing thermal challenges for the systems designer. The automotive electronic control unit (ECU) package faces the same challenge of thermal management as the industry in general. This is coupled with the latest European Union legislation (Euro 6 standard) which forced the ECU manufacturers to completely re-design their ECU platform with improved hardware and software capability. This will result in increased power densities and therefore, the ability to dissipate heat will be a key factor. A higher thermal conductivity (TC) material for the ECU housing (than the currently used Aluminium) could improve heat dissipation from the ECU. This paper critically reviews the state-of-the-art in thermal management materials which may be applicable to an automotive ECU. This review shows that of the different materials currently available, the Al/SiC composites in particular have very good potential for automotive ECU application. In terms of metal composites processing, the liquid metal infiltration process is recommended as it has a lower processing cost and it also has the ability to produce near net-shape materials.

  6. Materials performance in prototype Thermal Cycling Absorption Process (TCAP) columns

    International Nuclear Information System (INIS)

    Clark, E.A.

    1992-01-01

    Two prototype Thermal Cycling Absorption Process (TCAP) columns have been metallurgically examined after retirement, to determine the causes of failure and to evaluate the performance of the column container materials in this application. Leaking of the fluid heating and cooling subsystems caused retirement of both TCAP columns, not leaking of the main hydrogen-containing column. The aluminum block design TCAP column (AHL block TCAP) used in the Advanced Hydride Laboratory, Building 773-A, failed in one nitrogen inlet tube that was crimped during fabrication, which lead to fatigue crack growth in the tube and subsequent leaking of nitrogen from this tube. The Third Generation stainless steel design TCAP column (Third generation TCAP), operated in 773-A room C-061, failed in a braze joint between the freon heating and cooling tubes (made of copper) and the main stainless steel column. In both cases, stresses from thermal cycling and local constraint likely caused the nucleation and growth of fatigue cracks. No materials compatibility problems between palladium coated kieselguhr (the material contained in the TCAP column) and either aluminum or stainless steel column materials were observed. The aluminum-stainless steel transition junction appeared to be unaffected by service in the AHL block TCAP. Also, no evidence of cracking was observed in the AHL block TCAP in a location expected to experience the highest thermal shock fatigue in this design. It is important to limit thermal stresses caused by constraint in hydride systems designed to work by temperature variation, such as hydride storage beds and TCAP columns

  7. Thermal reactionomes reveal divergent responses to thermal extremes in warm and cool-climate ant species

    DEFF Research Database (Denmark)

    Stanton-Geddes, John; Nguyen, Andrew; Chick, Lacy

    2016-01-01

    across an experimental gradient. We characterized thermal reactionomes of two common ant species in the eastern U.S, the northern cool-climate Aphaenogaster picea and the southern warm-climate Aphaenogaster carolinensis, across 12 temperatures that spanned their entire thermal breadth.......The distributions of species and their responses to climate change are in part determined by their thermal tolerances. However, little is known about how thermal tolerance evolves. To test whether evolutionary extension of thermal limits is accomplished through enhanced cellular stress response...

  8. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi; Park, Youngjune; Petit, Camille; Park, Ah-Hyung Alissa

    2014-01-01

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  9. Thermal stability, swelling behavior and CO 2 absorption properties of Nanoscale Ionic Materials (NIMs)

    KAUST Repository

    Andrew Lin, Kun-Yi

    2014-11-11

    © The Royal Society of Chemistry 2015. Nanoscale Ionic Materials (NIMs) consist of a nanoscale core, a corona of charged brushes tethered on the surface of the core, and a canopy of the oppositely charged species linked to the corona. Unlike conventional polymeric nanocomposites, NIMs can display liquid-like behavior in the absence of solvents, have a negligible vapor pressure and exhibit unique solvation properties. These features enable NIMs to be a promising CO2 capture material. To optimize NIMs for CO2 capture, their structure-property relationships were examined by investigating the roles of the canopy and the core in their thermal stability, and thermally- and CO2-induced swelling behaviors. NIMs with different canopy sizes and core fractions were synthesized and their thermal stability as well as thermally- and CO2-induced swelling behaviors were determined using thermogravimetry, and ATR FT-IR and Raman spectroscopies. It was found that the ionic bonds between the canopy and the corona, as well as covalent bonds between the corona and the core significantly improved the thermal stability compared to pure polymer and polymer/nanofiller mixtures. A smaller canopy size and a larger core fraction led to a greater enhancement in thermal stability. This thermal stability enhancement was responsible for the long-term thermal stability of NIMs over 100 temperature swing cycles. Owing to their ordered structure, NIMs swelled less when heated or when they adsorbed CO2 compared to their corresponding polymers. This journal is

  10. Thermal Energetic Reactor with High Reproduction of Fission Materials

    International Nuclear Information System (INIS)

    Kotov, V.M.

    2012-01-01

    Existing thermal reactors are energy production scale limited because of low portion of raw uranium usage. Fast reactors are limited by reprocessing need of huge mass of raw uranium at the initial stage of development. The possibility of development of thermal reactors with high fission materials reproduction, which solves the problem, is discussed here. Neutron losses are decreased, uranium-thorium fuel with artificial fission materials equilibrium regime is used, additional in-core and out-core neutron sources are used for supplying of high fission materials reproduction. Liquid salt reactors can use dynamic loading regime for this purpose. Preferable construction is channel type reactor with heavy water moderator. Good materials for fuel element shells and channel walls are zirconium alloys enriched by 90Zr. Water cooled reactors with usage 12% of raw uranium and liquid metal cooled reactors with usage 25% of raw uranium are discussed. Reactors with additional neutron sources obtain full usage of raw uranium with small additional energy expenses. On the base of thermal reactors with high fission materials reproduction world atomic power engineering development supplying higher power and requiring smaller speed of raw uranium mining, than in the variant with fast reactors, is possible.

  11. Development of thermal energy storage materials for biomedical applications.

    Science.gov (United States)

    Shukla, A; Sharma, Atul; Shukla, Manjari; Chen, C R

    2015-01-01

    The phase change materials (PCMs) have been utilized widely for solar thermal energy storage (TES) devices. The quality of these materials to remain at a particular temperature during solid-liquid, liquid-solid phase transition can also be utilized for many biomedical applications as well and has been explored in recent past already. This study reports some novel PCMs developed by them, along with some existing PCMs, to be used for such biomedical applications. Interestingly, it was observed that the heating/cooling properties of these PCMs enhance the quality of a variety of biomedical applications with many advantages (non-electric, no risk of electric shock, easy to handle, easy to recharge thermally, long life, cheap and easily available, reusable) over existing applications. Results of the present study are quite interesting and exciting, opening a plethora of opportunities for more work on the subject, which require overlapping expertise of material scientists, biochemists and medical experts for broader social benefits.

  12. Emergency Response to Radioactive Material Transport Accidents

    International Nuclear Information System (INIS)

    EL-shinawy, R.M.K.

    2009-01-01

    Although transport regulations issued by IAEA is providing a high degree of safety during transport opertions,transport accidents involving packages containing radioactive material have occurred and will occur at any time. Whenever a transport accident involving radioactive material accurs, and many will pose no radiation safety problems, emergency respnose actioms are meeded to ensure that radiation safety is maintained. In case of transport accident that result in a significant relesae of radioactive material , loss of shielding or loss of criticality control , that consequences should be controlled or mitigated by proper emergency response actions safety guide, Emergency Response Plamming and Prepardness for transport accidents involving radioactive material, was published by IAEA. This guide reflected all requirememts of IAEA, regulations for safe transport of radioactive material this guide provide guidance to the publicauthorites and other interested organziation who are responsible for establishing such emergency arrangements

  13. Hazardous materials transportation and emergency response programs

    International Nuclear Information System (INIS)

    Joy, D.S.; Fore, C.S.

    1983-01-01

    This presentation consists of the following visual aids; (1) detailed routing capabilities of truck, rail, barge; (2) legislative data base for hazardous materials; and (3) emergency response of accident site Eddyville, Kentucky (airports in vicinity of Eddyville, KY)

  14. Instrumentation for thermal diffusivity determination of sintered materials

    International Nuclear Information System (INIS)

    Turquetti Filho, R.

    1990-01-01

    A new procedure to measure the sinterized materials thermal diffusivity, using the heat pulse method was developed in this work. The experimental data were performed at room temperature with UO sub(2), ThO sub(2), and Al sub(2)O sub(3) samples with 94%, 95%, and 96% of theoretical densities, respectively. Nondimensional root mean square deviation for theoretical function fitting was found to be on the order, of 10 sup(-3). The total error associated with the measurements for thermal diffusivity was ± 5%. (author)

  15. Selection of materials with potential in sensible thermal energy storage

    International Nuclear Information System (INIS)

    Fernandez, A.I.; Martinez, M.; Segarra, M.; Martorell, I.; Cabeza, L.F.

    2010-01-01

    Thermal energy storage is a technology under investigation since the early 1970s. Since then, numerous new applications have been found and much work has been done to bring this technology to the market. Nevertheless, the materials used either for latent or for sensible storage were mostly investigated 30 years ago, and the research has lead to improvement in their performance under different conditions of applications. In those years a significant number of new materials were developed in many fields other than storage and energy, but a great effort to characterize and classify these materials was done. Taking into account the fact that thousands of materials are known and a large number of new materials are developed every year, the authors use the methodology for materials selection developed by Prof. Ashby to give an overview of other materials suitable to be used in thermal energy storage. Sensible heat storage at temperatures between 150 and 200 C is defined as a case study and two different scenarios were considered: long term sensible heat storage and short term sensible heat storage. (author)

  16. Extremal Overall Elastic Response of Polycrystalline Materials

    DEFF Research Database (Denmark)

    Bendsøe, Martin P; Lipton, Robert

    1996-01-01

    Polycrystalline materials comprised of grains obtained froma single anisotropic material are considered in the frameworkof linear elasticity. No assumptions on the symmetry of thepolycrystal are made. We subject the material to independentexternal strain and stress fields with prescribed mean...... values.We show that the extremal overall elastic response is alwaysachieved by a configuration consisting of a single properlyoriented crystal. This result is compared to results for isotropicpolycrystals....

  17. Adaptive Responses to Thermal Stress in Mammals

    OpenAIRE

    Yasser Lenis Sanin; Angélica María Zuluaga Cabrera; Ariel Marcel Tarazona Morales

    2015-01-01

    The environment animals have to cope with is a combination of natural factors such as temperature. Extreme changes in these factors can alter homeostasis, which can lead to thermal stress. This stress can be due to either high temperatures or low temperatures. Energy transference for thermoregulation in homoeothermic animals occurs through several mechanisms: conduction, convection, radiation and evaporation. When animals are subjected to thermal stress, physiological mechanisms are activated...

  18. Preparation and thermal conductivity enhancement of composite phase change materials for electronic thermal management

    International Nuclear Information System (INIS)

    Wu, Weixiong; Zhang, Guoqing; Ke, Xiufang; Yang, Xiaoqing; Wang, Ziyuan; Liu, Chenzhen

    2015-01-01

    Highlights: • A kind of composite phase change material board (PCMB) is prepared and tested. • PCMB presents a large thermal storage capacity and enhanced thermal conductivity. • PCMB displays much better cooling effect in comparison to natural air cooling. • PCMB presents different cooling characteristics in comparison to ribbed radiator. - Abstract: A kind of phase change material board (PCMB) was prepared for use in the thermal management of electronics, with paraffin and expanded graphite as the phase change material and matrix, respectively. The as-prepared PCMB presented a large thermal storage capacity of 141.74 J/g and enhanced thermal conductivity of 7.654 W/(m K). As a result, PCMB displayed much better cooling effect in comparison to natural air cooling, i.e., much lower heating rate and better uniformity of temperature distribution. On the other hand, compared with ribbed radiator technology, PCMB also presented different cooling characteristics, demonstrating that they were suitable for different practical application

  19. 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.

  20. Metal-Organic-Inorganic Nanocomposite Thermal Interface Materials with Ultralow Thermal Resistances.

    Science.gov (United States)

    Yegin, Cengiz; Nagabandi, Nirup; Feng, Xuhui; King, Charles; Catalano, Massimo; Oh, Jun Kyun; Talib, Ansam J; Scholar, Ethan A; Verkhoturov, Stanislav V; Cagin, Tahir; Sokolov, Alexei V; Kim, Moon J; Matin, Kaiser; Narumanchi, Sreekant; Akbulut, Mustafa

    2017-03-22

    As electronic devices get smaller and more powerful, energy density of energy storage devices increases continuously, and moving components of machinery operate at higher speeds, the need for better thermal management strategies is becoming increasingly important. The removal of heat dissipated during the operation of electronic, electrochemical, and mechanical devices is facilitated by high-performance thermal interface materials (TIMs) which are utilized to couple devices to heat sinks. Herein, we report a new class of TIMs involving the chemical integration of boron nitride nanosheets (BNNS), soft organic linkers, and a copper matrix-which are prepared by the chemisorption-coupled electrodeposition approach. These hybrid nanocomposites demonstrate bulk thermal conductivities ranging from 211 to 277 W/(m K), which are very high considering their relatively low elastic modulus values on the order of 21.2-28.5 GPa. The synergistic combination of these properties led to the ultralow total thermal resistivity values in the range of 0.38-0.56 mm 2 K/W for a typical bond-line thickness of 30-50 μm, advancing the current state-of-art transformatively. Moreover, its coefficient of thermal expansion (CTE) is 11 ppm/K, forming a mediation zone with a low thermally induced axial stress due to its close proximity to the CTE of most coupling surfaces needing thermal management.

  1. 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

  2. Neutrophil Responses to Sterile Implant Materials.

    Directory of Open Access Journals (Sweden)

    Siddharth Jhunjhunwala

    Full Text Available In vivo implantation of sterile materials and devices results in a foreign body immune response leading to fibrosis of implanted material. Neutrophils, one of the first immune cells to be recruited to implantation sites, have been suggested to contribute to the establishment of the inflammatory microenvironment that initiates the fibrotic response. However, the precise numbers and roles of neutrophils in response to implanted devices remains unclear. Using a mouse model of peritoneal microcapsule implantation, we show 30-500 fold increased neutrophil presence in the peritoneal exudates in response to implants. We demonstrate that these neutrophils secrete increased amounts of a variety of inflammatory cytokines and chemokines. Further, we observe that they participate in the foreign body response through the formation of neutrophil extracellular traps (NETs on implant surfaces. Our results provide new insight into neutrophil function during a foreign body response to peritoneal implants which has implications for the development of biologically compatible medical devices.

  3. Microencapsulation of phase change materials with carbon nanotubes reinforced shell for enhancement of thermal conductivity

    Science.gov (United States)

    Cui, Weiwei; Xia, Yongpeng; Zhang, Huanzhi; Xu, Fen; Zou, Yongjin; Xiang, Cuili; Chu, Hailiang; Qiu, Shujun; Sun, Lixian

    2017-03-01

    Novel microencapsulated phase change materials (micro-PCMs) were synthesized via in-situ polymerization with modified carbon nanotubes(CNTs) reinforced melamine-formaldehyde resin as shell material and CNTs reinforced n-octadecane as PCMs core. DSC results confirm that the micro-PCMs possess good phase change behavior and excellent thermal cycling stability. Melting enthalpy of the micro-PCMs can achieve 133.1 J/g and has slight changes after 20 times of thermal cyclings. And the incorporation of CNTs supplies the micro-PCMs with fast thermal response rate which increases the crystallization temperature of the micro-PCMs. Moreover, the thermal conductivity of the micro-PCMs has been significantly enhanced by introducing CNTs into their shell and core materials. And the thermal conductivity of micro-PCMs with 1.67 wt.% CNTs can increase by 25%. These results exhibit that the obtained micro-PCMs have a good prospect in thermal energy storage applications.

  4. A theoretical analysis of local thermal equilibrium in fibrous materials

    Directory of Open Access Journals (Sweden)

    Tian Mingwei

    2015-01-01

    Full Text Available The internal heat exchange between each phase and the Local Thermal Equilibrium (LTE scenarios in multi-phase fibrous materials are considered in this paper. Based on the two-phase heat transfer model, a criterion is proposed to evaluate the LTE condition, using derived characteristic parameters. Furthermore, the LTE situations in isothermal/adiabatic boundary cases with two different heat sources (constant heat flux and constant temperature are assessed as special transient cases to test the proposed criterion system, and the influence of such different cases on their LTE status are elucidated. In addition, it is demonstrated that even the convective boundary problems can be generally estimated using this approach. Finally, effects on LTE of the material properties (thermal conductivity, volumetric heat capacity of each phase, sample porosity and pore hydraulic radius are investigated, illustrated and discussed in our study.

  5. Thermally responsive polymer electrolytes for inherently safe electrochemical energy storage

    Science.gov (United States)

    Kelly, Jesse C.

    Electrochemical double layer capacitors (EDLCs), supercapacitors and Li-ion batteries have emerged as premier candidates to meet the rising demands in energy storage; however, such systems are limited by thermal hazards, thermal runaway, fires and explosions, all of which become increasingly more dangerous in large-format devices. To prevent such scenarios, thermally-responsive polymer electrolytes (RPEs) that alter properties in electrochemical energy storage devices were designed and tested. These RPEs will be used to limit or halt device operation when temperatures increase beyond a predetermined threshold, therefore limiting further heating. The development of these responsive systems will offer an inherent safety mechanism in electrochemical energy storage devices, while preserving the performance, lifetimes, and versatility that large-format systems require. Initial work focused on the development of a model system that demonstrated the concept of RPEs in an electrochemical device. Aqueous electrolyte solutions of polymers exhibiting properties that change in response to temperature were developed for applications in EDLCs and supercapacitors. These "smart materials" provide a means to control electrochemical systems where polymer phase separation at high temperatures affects electrolyte properties and inhibits device performance. Aqueous RPEs were synthesized using N-isopropylacrylamide, which governs the thermal properties, and fractions of acrylic acid or vinyl sulfonic acids, which provide ions to the solution. The molecular properties of these aqueous RPEs, specifically the ionic composition, were shown to influence the temperature-dependent electrolyte properties and the extent to which these electrolytes control the energy storage characteristics of a supercapacitor device. Materials with high ionic content provided the highest room temperature conductivity and electrochemical activity; however, RPEs with low ionic content provided the highest "on

  6. Improving the Material Response for Slow Heat of Energetic Materials

    Energy Technology Data Exchange (ETDEWEB)

    Nichols, A L

    2010-03-08

    The goal of modern high explosive slow heat cookoff modeling is to understand the level of mechanical violence. This requires understanding the coupled thermal-mechanical-chemical system that such an environment creates. Recent advances have improved our ability to predict the time to event, and we have been making progress on predicting the mechanical response. By adding surface tension to the product gas pores in the high explosive, we have been able to reduce the current model's tendency to overpressurize confinement vessels. We describe the model and demonstrate how it affects a LX-10 STEX experiment. Issues associated with current product gas equations of state are described and examined.

  7. Advanced homogenization strategies in material modeling of thermally sprayed TBCs

    International Nuclear Information System (INIS)

    Bobzin, K.; Lugscheider, E.; Nickel, R.; Kashko, T.

    2006-01-01

    Thermal barrier coatings (TBC), obtained by atmospheric plasma spraying (APS), have a complex microstructure (lamellar, porous, micro-cracked). Process parameters take an influence on this microstructure. Two methods based on the homogenization for periodic structures are presented in this article. The methods are used to calculate the effective material behavior of APS-TBCs made of partially yttria stabilized zirconia (PYSZ) depending on the microstructure. (Abstract Copyright [2006], Wiley Periodicals, Inc.)

  8. Impact Testing of Orbiter Thermal Protection System Materials

    Science.gov (United States)

    Kerr, Justin

    2006-01-01

    This viewgraph presentation reviews the impact testing of the materials used in designing the shuttle orbiter thermal protection system (TPS). Pursuant to the Columbia Accident Investigation Board recommendations a testing program of the TPS system was instituted. This involved using various types of impactors in different sizes shot from various sizes and strengths guns to impact the TPS tiles and the Leading Edge Structural Subsystem (LESS). The observed damage is shown, and the resultant lessons learned are reviewed.

  9. Lower-Conductivity Ceramic Materials for Thermal-Barrier Coatings

    Science.gov (United States)

    Bansal, Narottam P.; Zhu, Dongming

    2006-01-01

    Doped pyrochlore oxides of a type described below are under consideration as alternative materials for high-temperature thermal-barrier coatings (TBCs). In comparison with partially-yttria-stabilized zirconia (YSZ), which is the state-of-the-art TBC material now in commercial use, these doped pyrochlore oxides exhibit lower thermal conductivities, which could be exploited to obtain the following advantages: For a given difference in temperature between an outer coating surface and the coating/substrate interface, the coating could be thinner. Reductions in coating thicknesses could translate to reductions in weight of hot-section components of turbine engines (e.g., combustor liners, blades, and vanes) to which TBCs are typically applied. For a given coating thickness, the difference in temperature between the outer coating surface and the coating/substrate interface could be greater. For turbine engines, this could translate to higher operating temperatures, with consequent increases in efficiency and reductions in polluting emissions. TBCs are needed because the temperatures in some turbine-engine hot sections exceed the maximum temperatures that the substrate materials (superalloys, Si-based ceramics, and others) can withstand. YSZ TBCs are applied to engine components as thin layers by plasma spraying or electron-beam physical vapor deposition. During operation at higher temperatures, YSZ layers undergo sintering, which increases their thermal conductivities and thereby renders them less effective as TBCs. Moreover, the sintered YSZ TBCs are less tolerant of stress and strain and, hence, are less durable.

  10. Metallic Nanocomposites as Next-Generation Thermal Interface Materials: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xuhui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); King, Charles C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nagabandi, Nirup [Texas A& M University; Oh, Jun K. [Texas A& M University; Akbulut, Mustafa [Texas A& M University; Yegin, Cengiz [Texas A& M University

    2017-09-14

    Thermal interface materials (TIMs) are an integral and important part of thermal management in electronic devices. The electronic devices are becoming more compact and powerful. This increase in power processed or passing through the devices leads to higher heat fluxes and makes it a challenge to maintain temperatures at the optimal level during operation. Herein, we report a free standing nanocomposite TIM in which boron nitride nanosheets (BNNS) are uniformly dispersed in copper matrices via an organic linker, thiosemicarbazide. Integration of these metal-organic-inorganic nanocomposites was made possible by a novel electrodeposition technique where the functionalized BNNS (f-BNNS) experience the Brownian motion and reach the cathode through diffusion, while the nucleation and growth of the copper on the cathode occurs via the electrochemical reduction. Once the f-BNNS bearing carbonothioyl/thiol groups on the terminal edges come into the contact with copper crystals, the chemisorption reaction takes place. We performed thermal, mechanical, and structural characterization of these nanocomposites using scanning electron microcopy (SEM), diffusive laser flash (DLF) analysis, phase-sensitive transient thermoreflectence (PSTTR), and nanoindentation. The nanocomposites exhibited a thermal conductivity ranging from 211 W/mK to 277 W/mK at a filler mass loading of 0-12 wt.percent. The nanocomposites also have about 4 times lower hardness as compared to copper, with values ranging from 0.27 GPa to 0.41 GPa. The structural characterization studies showed that most of the BNNS are localized at grain boundaries - which enable efficient thermal transport while making the material soft. PSTTR measurements revealed that the synergistic combinations of these properties yielded contact resistances on the order of 0.10 to 0.13 mm2K/W, and the total thermal resistance of 0.38 to 0.56 mm2K/W at bondline thicknesses of 30-50 um. The coefficient of thermal expansion (CTE) of the

  11. Metallic Nanocomposites as Next-Generation Thermal Interface Materials

    Energy Technology Data Exchange (ETDEWEB)

    Feng, Xuhui [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Narumanchi, Sreekant V [National Renewable Energy Laboratory (NREL), Golden, CO (United States); King, Charles C [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Nagabandi, Nirup [Texas A& M University; Oh, Jun Kyun [Texas A& M University; Akbulut, Mustafa [Texas A& M University; Yegin, Cengiz [Texas A& M University

    2017-07-27

    Thermal interface materials (TIMs) are an integral and important part of thermal management in electronic devices. The electronic devices are becoming more compact and powerful. This increase in power processed or passing through the devices leads to higher heat fluxes and makes it a challenge to maintain temperatures at the optimal level during operation. Herein, we report a free standing nanocomposite TIM in which boron nitride nanosheets (BNNS) are uniformly dispersed in copper matrices via an organic linker, thiosemicarbazide. Integration of these metal-organic-inorganic nanocomposites was made possible by a novel electrodeposition technique where the functionalized BNNS (f-BNNS) experience the Brownian motion and reach the cathode through diffusion, while the nucleation and growth of the copper on the cathode occurs via the electrochemical reduction. Once the f-BNNS bearing carbonothioyl/thiol groups on the terminal edges come into the contact with copper crystals, the chemisorption reaction takes place. We performed thermal, mechanical, and structural characterization of these nanocomposites using scanning electron microcopy (SEM), diffusive laser flash (DLF) analysis, phase-sensitive transient thermoreflectence (PSTTR), and nanoindentation. The nanocomposites exhibited a thermal conductivity ranging from 211 W/mK to 277 W/mK at a filler mass loading of 0-12 wt.percent. The nanocomposites also have about 4 times lower hardness as compared to copper, with values ranging from 0.27 GPa to 0.41 GPa. The structural characterization studies showed that most of the BNNS are localized at grain boundaries - which enable efficient thermal transport while making the material soft. PSTTR measurements revealed that the synergistic combinations of these properties yielded contact resistances on the order of 0.10 to 0.13 mm2K/W, and the total thermal resistance of 0.38 to 0.56 mm2K/W at bondline thicknesses of 30-50 um. The coefficient of thermal expansion (CTE) of the

  12. Testing of High Thermal Cycling Stability of Low Strength Concrete as a Thermal Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Chao Wu

    2016-09-01

    Full Text Available Concrete has the potential to become a solution for thermal energy storage (TES integrated in concentrating solar power (CSP systems due to its good thermal and mechanical properties and low cost of material. In this study, a low strength concrete (C20 is tested at high temperatures up to 600 °C. Specimens are thermally cycled at temperatures in the range of 400–300 °C, 500–300 °C, and 600–300 °C, which TES can reach in operation. For comparison, specimens also cycled at temperature in the range of 400–25 °C (room temperature, 500–25 °C, and 600–25 °C. It is found from the test results that cracks are not observed on the surfaces of concrete specimens until the temperature is elevated up to 500 °C. There is mechanical deterioration of concrete after exposure to high temperature, especially to high thermal cycles. The residual compressive strength of concrete after 10 thermal cycles between 600 °C and 300 °C is about 58.3%, but the specimens remain stable without spalling, indicating possible use of low strength concrete as a TES material.

  13. Applications of graphite-enabled phase change material composites to improve thermal performance of cementitious materials

    Science.gov (United States)

    Li, Mingli; Lin, Zhibin; Wu, Lili; Wang, Jinhui; Gong, Na

    2017-11-01

    Enhancing the thermal efficiency to decrease the energy consumption of structures has been the topic of much research. In this study, a graphite-enabled microencapsulated phase change material (GE-MEPCM) was used in the production of a novel thermal energy storage engineered cementitious composite feathering high heat storage capacity and enhanced thermal conductivity. The surface morphology and particle size of the microencapsulated phase change material (MEPCM) were investigated by scanning electron microscopy (SEM). Thermal properties of MEPCM was determined using differential scanning calorimetry (DSC). In addition, thermal and mechanical properties of the cementitious mortar with different admixtures were explored and compared with those of a cementitious composite. It was shown that the latent heat of MEPCM was 162 J/g, offering much better thermal energy storage capacity to the cementitious composite. However, MEPCM was found to decrease the thermal conductivity of the composite, which can be effectively solved by adding natural graphite (NG). Moreover, the incorporation of MEPCM has a certain decrease in the compressive strength, mainly due to the weak interfaces between MEPCM and cement matrix.

  14. Thermal properties of a novel nanoencapsulated phase change material for thermal energy storage

    International Nuclear Information System (INIS)

    Fuensanta, Mónica; Paiphansiri, Umaporn; Romero-Sánchez, María Dolores; Guillem, Celia; López-Buendía, Ángel M.; Landfester, Katharina

    2013-01-01

    Highlights: • A paraffin wax RT80 was encapsulated in styrene–butyl acrylate copolymer as polymer shell using miniemulsion polymerization process to obtain a novel nanoencapsulated PCM with 80 °C melting temperature. • Nano-PCMs have high compact structure, spherical morphology and thermal stability. • The nano-PCMs have potential applications as thermal energy storage materials. - Abstract: A novel nanoencapsulation of a paraffine type phase change material, RT80, in a styrene–butyl acrylate copolymer shell using the miniemulsion polymerization process was carried out. General characteristics of the RT80 nanoparticles in terms of thermal properties, morphology, chemical composition and particle size distribution were characterized by Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Dynamic Light Scattering (DLS). The influence of different monomers (styrene, butyl acrylate) and the surfactant/paraffin mass ratios on nanoparticles properties such as thermal capacity, particle size and morphology were systematically investigated. In all cases studied, encapsulation efficiency was close to 80 wt% with a particle size distribution between 52 and 112 nm and regular spherical shape and uniform structure. The amount of encapsulated paraffin achieved was comprised between 8 and 20%. Melting and crystallization heats were found to be approximately 5–25 J g −1 , mainly depending on surfactant/paraffin mass ratio. Melting temperature of RT80 nanoparticles slightly decreased (1–7 °C) respect to the raw RT80. In addition, the encapsulated RT80 nanoparticles show thermal stability even after 200 thermal (heat-cooling) cycles

  15. Thermal properties of a novel nanoencapsulated phase change material for thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Fuensanta, Mónica, E-mail: monica.fuensanta@aidico.es [AIDICO, Technological Institute of Construction, Camí de Castella, 4, 03660 Novelda, Alicante (Spain); Paiphansiri, Umaporn [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany); Romero-Sánchez, María Dolores, E-mail: md.romero@aidico.es [AIDICO, Technological Institute of Construction, Camí de Castella, 4, 03660 Novelda, Alicante (Spain); Guillem, Celia; López-Buendía, Ángel M. [AIDICO, Technological Institute of Construction, Camí de Castella, 4, 03660 Novelda, Alicante (Spain); Landfester, Katharina [Max Planck Institute for Polymer Research, Ackermannweg 10, 55128 Mainz (Germany)

    2013-08-10

    Highlights: • A paraffin wax RT80 was encapsulated in styrene–butyl acrylate copolymer as polymer shell using miniemulsion polymerization process to obtain a novel nanoencapsulated PCM with 80 °C melting temperature. • Nano-PCMs have high compact structure, spherical morphology and thermal stability. • The nano-PCMs have potential applications as thermal energy storage materials. - Abstract: A novel nanoencapsulation of a paraffine type phase change material, RT80, in a styrene–butyl acrylate copolymer shell using the miniemulsion polymerization process was carried out. General characteristics of the RT80 nanoparticles in terms of thermal properties, morphology, chemical composition and particle size distribution were characterized by Differential Scanning Calorimetry (DSC), Thermal Gravimetric Analysis (TGA), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR) and Dynamic Light Scattering (DLS). The influence of different monomers (styrene, butyl acrylate) and the surfactant/paraffin mass ratios on nanoparticles properties such as thermal capacity, particle size and morphology were systematically investigated. In all cases studied, encapsulation efficiency was close to 80 wt% with a particle size distribution between 52 and 112 nm and regular spherical shape and uniform structure. The amount of encapsulated paraffin achieved was comprised between 8 and 20%. Melting and crystallization heats were found to be approximately 5–25 J g{sup −1}, mainly depending on surfactant/paraffin mass ratio. Melting temperature of RT80 nanoparticles slightly decreased (1–7 °C) respect to the raw RT80. In addition, the encapsulated RT80 nanoparticles show thermal stability even after 200 thermal (heat-cooling) cycles.

  16. The thermal and mechanical properties of a low-density glass-fiber-reinforced elastomeric ablation material

    Science.gov (United States)

    Engelke, W. T.; Robertson, R. W.; Bush, A. L.; Pears, C. D.

    1974-01-01

    An evaluation of the thermal and mechanical properties was performed on a molded low-density elastomeric ablation material designated as Material B. Both the virgin and charred states were examined to provide meaningful inputs to the design of a thermal protection system. Chars representative of the flight chars formed during ablation were prepared in a laboratory furnace from 600 K to 1700 K and properties of effective thermal conductivity, heat capacity, porosity and permeability were determined on the furnace chars formed at various temperature levels within the range. This provided a boxing of the data which will enable the prediction of the transient response of the material during flight ablation.

  17. Thermal Response of Cooled Silicon Nitride Plate Due to Thermal Conductivity Effects Analyzed

    Science.gov (United States)

    Baaklini, George Y.; Abdul-Aziz, Ali; Bhatt, Ramakrishna

    2003-01-01

    Lightweight, strong, tough high-temperature materials are required to complement efficiency improvements for next-generation gas turbine engines that can operate with minimum cooling. Because of their low density, high-temperature strength, and high thermal conductivity, ceramics are being investigated as materials to replace the nickelbase superalloys that are currently used for engine hot-section components. Ceramic structures can withstand higher operating temperatures and a harsh combustion environment. In addition, their low densities relative to metals help reduce component mass (ref. 1). To complement the effectiveness of the ceramics and their applicability for turbine engine applications, a parametric study using the finite element method is being carried out. The NASA Glenn Research Center remains very active in conducting and supporting a variety of research activities related to ceramic matrix composites through both experimental and analytical efforts (ref. 1). The objectives of this work are to develop manufacturing technology, develop a thermal and environmental barrier coating (TBC/EBC), develop an analytical modeling capability to predict thermomechanical stresses, and perform a minimal burner rig test on silicon nitride (Si3N4) and SiC/SiC turbine nozzle vanes under simulated engine conditions. Moreover, we intend to generate a detailed database of the material s property characteristics and their effects on structural response. We expect to offer a wide range of data since the modeling will account for other variables, such as cooling channel geometry and spacing. Comprehensive analyses have begun on a plate specimen with Si3N4 cooling holes.

  18. Estimation of fracture parameters in foam core materials using thermal techniques

    DEFF Research Database (Denmark)

    Dulieu-Barton, J. M.; Berggreen, Christian; Boyenval Langlois, C.

    2010-01-01

    is described. A mode I simulated crack in the form of a machined notch is used to establish the feasibility of the TSA approach to derive stress intensity factors for the foam material. The overall goal is to demonstrate that thermal techniques have the ability to provide deeper insight into the behaviour......The paper presents some initial work on establishing the stress state at a crack tip in PVC foam material using a non-contact infra-red technique known as thermoelastic stress analysis (TSA). A parametric study of the factors that may affect the thermoelastic response of the foam material...

  19. Impact of vacancy ordering on thermal transport in crystalline phase-change materials.

    Science.gov (United States)

    Siegert, K S; Lange, F R L; Sittner, E R; Volker, H; Schlockermann, C; Siegrist, T; Wuttig, M

    2015-01-01

    Controlling thermal transport in solids is of paramount importance for many applications. Often thermal management is crucial for a device's performance, as it affects both reliability and power consumption. A number of intricate concepts have been developed to address this challenge, such as diamond-like coatings to enhance the thermal conductivity or low symmetry complex super-structures to reduce it. Here, a different approach is pursued, where we explore the potential of solids with a high yet controllable degree of disorder. Recently, it has been demonstrated that an unconventionally high degree of structural disorder characterizes a number of crystalline phase-change materials (PCMs). This disorder strongly impacts electronic transport and even leads to disorder induced localization (Anderson localization). This raises the question how thermal transport is affected by such conditions. Here thermal transport in highly disordered crystalline Ge-Sb-Te (GST) based PCMs is investigated. Glass-like thermal properties are observed for several crystalline PCMs, which are attributed to strong scattering by disordered point defects. A systematic study of different compounds along the pseudo-binary line between GeTe and Sb2Te3 reveals that disordered vacancies act as point defects responsible for pronounced phonon scattering. Annealing causes a gradual ordering of the vacancies and leads to a more 'crystal-like' thermal conductivity. While both vibrational and electronic degrees of freedom are affected by disorder, the consequences differ for different stoichiometries. This opens up a pathway to tune electrical and thermal transport by controlling the degree of disorder. Materials with tailored transport properties may not only help to improve power efficiency and scaling in upcoming phase-change memories but are also of fundamental interest in the field of thermoelectric materials.

  20. Impact of vacancy ordering on thermal transport in crystalline phase-change materials

    International Nuclear Information System (INIS)

    Siegert, K S; Lange, F R L; Sittner, E R; Volker, H; Schlockermann, C; Wuttig, M; Siegrist, T

    2015-01-01

    Controlling thermal transport in solids is of paramount importance for many applications. Often thermal management is crucial for a device's performance, as it affects both reliability and power consumption. A number of intricate concepts have been developed to address this challenge, such as diamond-like coatings to enhance the thermal conductivity or low symmetry complex super-structures to reduce it. Here, a different approach is pursued, where we explore the potential of solids with a high yet controllable degree of disorder. Recently, it has been demonstrated that an unconventionally high degree of structural disorder characterizes a number of crystalline phase-change materials (PCMs). This disorder strongly impacts electronic transport and even leads to disorder induced localization (Anderson localization). This raises the question how thermal transport is affected by such conditions. Here thermal transport in highly disordered crystalline Ge–Sb–Te (GST) based PCMs is investigated. Glass-like thermal properties are observed for several crystalline PCMs, which are attributed to strong scattering by disordered point defects. A systematic study of different compounds along the pseudo-binary line between GeTe and Sb 2 Te 3 reveals that disordered vacancies act as point defects responsible for pronounced phonon scattering. Annealing causes a gradual ordering of the vacancies and leads to a more ‘crystal-like’ thermal conductivity. While both vibrational and electronic degrees of freedom are affected by disorder, the consequences differ for different stoichiometries. This opens up a pathway to tune electrical and thermal transport by controlling the degree of disorder. Materials with tailored transport properties may not only help to improve power efficiency and scaling in upcoming phase-change memories but are also of fundamental interest in the field of thermoelectric materials. (key issues review)

  1. Human transient response under local thermal stimulation

    Directory of Open Access Journals (Sweden)

    Wang Lijuan

    2017-01-01

    Full Text Available Human body can operate physiological thermoregulation system when it is exposed to cold or hot environment. Whether it can do the same work when a local part of body is stimulated by different temperatures? The objective of this paper is to prove it. Twelve subjects are recruited to participate in this experiment. After stabilizing in a comfort environment, their palms are stimulated by a pouch of 39, 36, 33, 30, and 27°C. Subject’s skin temperature, heart rate, heat flux of skin, and thermal sensation are recorded. The results indicate that when local part is suffering from harsh temperature, the whole body is doing physiological thermoregulation. Besides, when the local part is stimulated by high temperature and its thermal sensation is warm, the thermal sensation of whole body can be neutral. What is more, human body is more sensitive to cool stimulation than to warm one. The conclusions are significant to reveal and make full use of physiological thermoregulation.

  2. Improved thermal storage material for portable life support systems

    Science.gov (United States)

    Kellner, J. D.

    1975-01-01

    The availability of thermal storage materials that have heat absorption capabilities substantially greater than water-ice in the same temperature range would permit significant improvements in performance of projected portable thermal storage cooling systems. A method for providing increased heat absorption by the combined use of the heat of solution of certain salts and the heat of fusion of water-ice was investigated. This work has indicated that a 30 percent solution of potassium bifluoride (KHF2) in water can absorb approximately 52 percent more heat than an equal weight of water-ice, and approximately 79 percent more heat than an equal volume of water-ice. The thermal storage material can be regenerated easily by freezing, however, a lower temperature must be used, 261 K as compared to 273 K for water-ice. This work was conducted by the United Aircraft Research Laboratories as part of a program at Hamilton Standard Division of United Aircraft Corporation under contract to NASA Ames Research Center.

  3. Pressure effects on thermal conductivity and expansion of geologic materials

    International Nuclear Information System (INIS)

    Sweet, J.N.

    1979-02-01

    Through analysis of existing data, an estimate is made of the effect of pressure or depth on the thermal conductivity and expansion of geologic materials which could be present in radioactive waste repositories. In the case of homogeneous dense materials, only small shifts are predicted to occur at depths less than or equal to 3 km, and these shifts will be insignificant as compared with those caused by temperature variations. As the porosity of the medium increases, the variation of conductivity and expansion with pressure becomes greater, with conductivity increasing and expansion decreasing as pressure increases. The pressure dependence of expansion can be found from data on the temperature variation of the isobaric compressibility. In a worst case estimate, a decrease in expansion of approx. 25% is predicted for 5% porous sandstone at a depth of 3 km. The thermal conductivity of a medium with gaseous inclusions increases as the porosity decreases, with the magnitude of the increase being dependent on the details of the porosity collapse. Based on analysis of existing data on tuff and sandstone, a weighted geometric mean formula is recommended for use in calculating the conductivity of porous rock. As a result of this study, it is recommended that measurement of rock porosity versus depth receive increased attention in exploration studies and that the effect of porosity on thermal conductivity and expansion should be examined in more detail

  4. Inductive thermal plasma generation applied for the materials coating

    International Nuclear Information System (INIS)

    Pacheco, J.; Pena, R.; Cota, G.; Segovia, A.; Cruz, A.

    1996-01-01

    The coatings by thermal plasma are carried out introducing particles into a plasma system where they are accelerated and melted (total or partially) before striking the substrate to which they adhere and are suddenly cooled down. The nature of consolidation and solidification of the particles allows to have control upon the microstructure of the deposit. This technique is able to deposit any kind of material that is suitable to be merged (metal, alloy, ceramic, glass) upon any type of substrate (metal, graphite, ceramic, wood) with an adjustable thickness ranging from a few microns up to several millimeters. The applications are particularly focused to the coating of materials in order to improve their properties of resistance to corrosion, thermal and mechanical efforts as well as to preserve the properties of the so formed compound. In this work the electromagnetic induction phenomenon in an ionized medium by means of electric conductivity, is described. Emphasis is made on the devices and control systems employed in order to generate the thermal plasma and in carrying out the coatings of surfaces by the projection of particles based on plasma

  5. Development of Tailorable Electrically Conductive Thermal Control Material Systems

    Science.gov (United States)

    Deshpande, M. S.; Harada, Y.

    1997-01-01

    The optical characteristics of surfaces on spacecraft are fundamental parameters in controlling its temperature. Passive thermal control coatings with designed solar absorptance and infrared emittance properties have been developed and have been in use for some time. In this total space environment, the coating must be stable and maintain its desired optical properties as well as mechanical properties for the course of the mission lifetime. The mission lifetimes are increasing and in our quest to save weight, newer substrates are being integrated which limit electrical grounding schemes. All of this has added to already existing concerns about spacecraft charging and related spacecraft failures or operational failures. The concern is even greater for thermal control surfaces that are very large. One way of alleviating such concerns is to design new thermal control material systems (TCMS) that can help to mitigate charging via providing charge leakage paths. The objective of this program was to develop two types of passive electrically conductive TCMS. The first was a highly absorbing/emitting black surface and the second was a low (alpha(sub s)/epsilon(sub N)) type white surface. The surface resistance goals for the black absorber was 10(exp 4) to 10(exp 9) Omega/square, and for the white surfaces it was 10(exp 6) to 10(exp 10) Omega/square. Several material system concepts were suggested and evaluated for space environment stability and electrical performance characterization. Our efforts in designing and evaluating these material systems have resulted in several developments. New concepts, pigments and binders have been developed to provide new engineering quality TCMS. Some of these have already found application on space hardware, some are waiting to be recognized by thermal designers, and some require further detailed studies to become state-of-the-art for future space hardware and space structures. Our studies on baseline state-of-the-art materials and

  6. Thermal behavior of the duct applied functionally graded material

    Energy Technology Data Exchange (ETDEWEB)

    Park, Jung Sun; Yoon, Dong Young; Im, Jong Bin [Hankuk Aviation Univ., Goyang (Korea, Republic of)

    2004-07-01

    In Unmanned Aerial Vehicles (UAV), the high temperature results from friction among the air, combustion of fuel in engine and combustion gas of a nozzle. The high temperature may cause serious damages in UAV structure. The Functionally Graded Material(FGM) is chosen as a material of the engine duct structure. Thermal stress analysis of FGM is performed in this paper. FGM is composed of two constituent materials that are mixed up according to the specific volume fraction distribution in order to withstand high temperature. Therefore, hoop stress, axial stress and shear stress of duct with 2 layers, 4 layers and 8 layers FGM are compared and analyzed respectively. In addition, the creep behavior of FGM used in duct structure of an engine is analyzed for better understanding of FGM characteristics.

  7. Standard Practice for Evaluating Solar Absorptive Materials for Thermal Applications

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2007-01-01

    1.1 This practice covers a testing methodology for evaluating absorptive materials used in flat plate or concentrating collectors, with concentrating ratios not to exceed five, for solar thermal applications. This practice is not intended to be used for the evaluation of absorptive surfaces that are (1) used in direct contact with, or suspended in, a heat-transfer liquid, (that is, trickle collectors, direct absorption fluids, etc.); (2) used in evacuated collectors; or (3) used in collectors without cover plate(s). 1.2 Test methods included in this practice are property measurement tests and aging tests. Property measurement tests provide for the determination of various properties of absorptive materials, for example, absorptance, emittance, and appearance. Aging tests provide for exposure of absorptive materials to environments that may induce changes in the properties of test specimens. Measuring properties before and after an aging test provides a means of determining the effect of the exposure. 1.3 Th...

  8. Thermal responses of shape memory alloy artificial anal sphincters

    Science.gov (United States)

    Luo, Yun; Takagi, Toshiyuki; Matsuzawa, Kenichi

    2003-08-01

    This paper presents a numerical investigation of the thermal behavior of an artificial anal sphincter using shape memory alloys (SMAs) proposed by the authors. The SMA artificial anal sphincter has the function of occlusion at body temperature and can be opened with a thermal transformation induced deformation of SMAs to solve the problem of severe fecal incontinence. The investigation of its thermal behavior is of great importance in terms of practical use in living bodies as a prosthesis. In this work, a previously proposed phenomenological model was applied to simulate the thermal responses of SMA plates that had undergone thermally induced transformation. The numerical approach for considering the thermal interaction between the prosthesis and surrounding tissues was discussed based on the classical bio-heat equation. Numerical predictions on both in vitro and in vivo cases were verified by experiments with acceptable agreements. The thermal responses of the SMA artificial anal sphincter were discussed based on the simulation results, with the values of the applied power and the geometric configuration of thermal insulation as parameters. The results obtained in the present work provided a framework for the further design of SMA artificial sphincters to meet demands from the viewpoint of thermal compatibility as prostheses.

  9. Electric vehicles batteries thermal management systems employing phase change materials

    Science.gov (United States)

    Ianniciello, Lucia; Biwolé, Pascal Henry; Achard, Patrick

    2018-02-01

    Battery thermal management is necessary for electric vehicles (EVs), especially for Li-ion batteries, due to the heat dissipation effects on those batteries. Usually, air or coolant circuits are employed as thermal management systems in Li-ion batteries. However, those systems are expensive in terms of investment and operating costs. Phase change materials (PCMs) may represent an alternative which could be cheaper and easier to operate. In fact, PCMs can be used as passive or semi-passive systems, enabling the global system to sustain near-autonomous operations. This article presents the previous developments introducing PCMs for EVs battery cooling. Different systems are reviewed and solutions are proposed to enhance PCMs efficiency in those systems.

  10. Fiber Optic Thermal Health Monitoring of Aerospace Structures and Materials

    Science.gov (United States)

    Wu, Meng-Chou; Winfree, William P.; Allison, Sidney G.

    2009-01-01

    A new technique is presented for thermographic detection of flaws in materials and structures by performing temperature measurements with fiber Bragg gratings. Individual optical fibers with multiple Bragg gratings employed as surface temperature sensors were bonded to the surfaces of structures with subsurface defects or thickness variations. Both during and following the application of a thermal heat flux to the surface, the individual Bragg grating sensors measured the temporal and spatial temperature variations. The investigated structures included a 10-ply composite specimen with subsurface delaminations of various sizes and depths. The data obtained from grating sensors were further analyzed with thermal modeling to reveal particular characteristics of the interested areas. These results were found to be consistent with those from conventional thermography techniques. Limitations of the technique were investigated using both experimental and numerical simulation techniques. Methods for performing in-situ structural health monitoring are discussed.

  11. 78 FR 8202 - Meeting of the Joint ACRS Subcommittees on Thermal Hydraulic Phenomena and Materials, Metallurgy...

    Science.gov (United States)

    2013-02-05

    ... NUCLEAR REGULATORY COMMISSION Advisory Committee on Reactor Safeguards (ACRS) Meeting of the Joint ACRS Subcommittees on Thermal Hydraulic Phenomena and Materials, Metallurgy and Reactor Fuels; Notice of Meeting The Joint ACRS Subcommittees on Thermal Hydraulic Phenomena and Materials, Metallurgy and...

  12. Thermal Stability and Material Balance of Nanomaterials in Waste Incineration

    Science.gov (United States)

    Paur, H.-R.; Baumann, W.; Hauser, M.; Lang, I.; Teuscher, N.; Seifert, H.; Stapf, D.

    2017-06-01

    Nanostructured materials are widely used to improve the properties of consumer products such as tires, cosmetics, light weight equipment etc. Due to their complex composition these products are hardly recycled and thermal treatment is preferred. In this study we investigated the thermal stability and material balance of nanostructured metal oxides in flames and in an industrial waste incinerator. We studied the size distribution of nanostructured metal oxides (CeO2, TiO2, SiO2) in a flame reactor and in a heated reaction tube. In the premixed ethylene/air flame, nano-structured CeO2 partly evaporates forming a new particle mode. This is probably due to chemical reactions in the flame. In addition sintering of agglomerates takes place in the flame. In the electrically heated reaction tube however only sintering of the agglomerated nanomaterials is observed. Ceria has a low background in waste incinerators and is therefore a suitable tracer for investigating the fate of nanostructured materials. Low concentrations of Ceria were introduced by a two-phase nozzle into the post-combustion zone of a waste incinerator. By the incineration of coal dust in a burning chamber the Ceria nanoparticles are mainly found in the size range of the fly ash (1 - 10 µm) because of agglomeration. With gas as a fuel less agglomeration was observed and the Ceria nanoparticles were in the particle size range below 1 µm.

  13. Thermal Stability and Material Balance of Nanomaterials in Waste Incineration

    International Nuclear Information System (INIS)

    Paur, H.-R.; Baumann, W.; Hauser, M.; Lang, I.; Teuscher, N.; Seifert, H.; Stapf, D.

    2017-01-01

    Nanostructured materials are widely used to improve the properties of consumer products such as tires, cosmetics, light weight equipment etc. Due to their complex composition these products are hardly recycled and thermal treatment is preferred. In this study we investigated the thermal stability and material balance of nanostructured metal oxides in flames and in an industrial waste incinerator. We studied the size distribution of nanostructured metal oxides (CeO 2 , TiO 2 , SiO 2 ) in a flame reactor and in a heated reaction tube. In the premixed ethylene/air flame, nano-structured CeO 2 partly evaporates forming a new particle mode. This is probably due to chemical reactions in the flame. In addition sintering of agglomerates takes place in the flame. In the electrically heated reaction tube however only sintering of the agglomerated nanomaterials is observed. Ceria has a low background in waste incinerators and is therefore a suitable tracer for investigating the fate of nanostructured materials. Low concentrations of Ceria were introduced by a two-phase nozzle into the post-combustion zone of a waste incinerator. By the incineration of coal dust in a burning chamber the Ceria nanoparticles are mainly found in the size range of the fly ash (1 – 10 µm) because of agglomeration. With gas as a fuel less agglomeration was observed and the Ceria nanoparticles were in the particle size range below 1 µm. (paper)

  14. Thermal Conductivity of Ceramic Thermal Barrier and Environmental Barrier Coating Materials

    Science.gov (United States)

    Zhu, Dong-Ming; Bansal, Narottam P.; Lee, Kang N.; Miller, Robert A.

    2001-01-01

    Thermal barrier and environmental barrier coatings (TBC's and EBC's) have been developed to protect metallic and Si-based ceramic components in gas turbine engines from high temperature attack. Zirconia-yttria based oxides and (Ba,Sr)Al2Si2O8(BSAS)/mullite based silicates have been used as the coating materials. In this study, thermal conductivity values of zirconia-yttria- and BSAS/mullite-based coating materials were determined at high temperatures using a steady-state laser heat flux technique. During the laser conductivity test, the specimen surface was heated by delivering uniformly distributed heat flux from a high power laser. One-dimensional steady-state heating was achieved by using thin disk specimen configuration (25.4 mm diam and 2 to 4 mm thickness) and the appropriate backside air-cooling. The temperature gradient across the specimen thickness was carefully measured by two surface and backside pyrometers. The thermal conductivity values were thus determined as a function of temperature based on the 1-D heat transfer equation. The radiation heat loss and laser absorption corrections of the materials were considered in the conductivity measurements. The effects of specimen porosity and sintering on measured conductivity values were also evaluated.

  15. Studies on thermal properties and thermal control effectiveness of a new shape-stabilized phase change material with high thermal conductivity

    International Nuclear Information System (INIS)

    Cheng Wenlong; Liu Na; Wu Wanfan

    2012-01-01

    In order to overcome the difficulty of conventional phase change materials (PCMs) in packaging, the shape-stabilized PCMs are proposed to be used in the electronic device thermal control. However, the conventional shape-stabilized PCMs have the drawback of lower thermal conductivity, so a new shape-stabilized PCM with high thermal conductivity, which is suitable for thermal control of electronic devices, is prepared. The thermal properties of n-octadecane-based shape-stabilized PCM are tested and analyzed. The heat storage/release performance is studied by numerical simulation. Its thermal control effect for electronic devices is also discussed. The results show that the expanded graphite (EG) can greatly improve the thermal conductivity of the material with little effect on latent heat and phase change temperature. When the mass fraction of EG is 5%, thermal conductivity has reached 1.76 W/(m K), which is over 4 times than that of the original one. Moreover, the material has larger latent heat and good thermal stability. The simulation results show that the material can have good heat storage/release performance. The analysis of the effect of thermal parameters on thermal control effect for electronic devices provides references to the design of phase change thermal control unit. - Highlights: ► A new shape-stabilized PCM with higher thermal conductivity is prepared. ► The material overcomes the packaging difficulty of traditional PCMs used in thermal control unit. ► The EG greatly improves thermal conductivity with little effect on latent heat. ► The material has high thermal stability and good heat storage/release performance. ► The effectiveness of the material for electronic device thermal control is proved.

  16. Radioactive materials transportation emergency response plan

    International Nuclear Information System (INIS)

    Karmali, N.

    1987-05-01

    Ontario Hydro transports radioactive material between its nuclear facilities, Atomic Energy of Canada Limited at Chalk River Laboratories and Radiochemical Company in Kanata, on a regular basis. Ontario Hydro also occasionally transports to Whiteshell Laboratories, Hydro-Quebec and New Brunswick Electric Power Commission. Although there are stringent packaging and procedural requirements for these shipments, Ontario Hydro has developed a Radioactive Materials Transportation Emergency Response Plan in the event that there is an accident. The Transportation Emergency Response plan is based on six concepts: 1) the Province id divided into three response areas with each station (Pickering, Darlington, Bruce) having identified response areas; 2) response is activated via a toll-free number. A shift supervisor at Pickering will answer the call, determine the hazards involved from the central shipment log and provide on-line advice to the emergency worker. At the same time he will notify the nearest Ontario Hydro area office to provide initial corporate response, and will request the nearest nuclear station to provide response assistance; 3) all stations have capability in terms of trained personnel and equipment to respond to an accident; 4) all Ontario Hydro shipments are logged with Pickering NGS. Present capability is based on computerized logging with the computer located in the shift office at Pickering to allow quick access to information on the shipment; 5) there is a three tier structure for emergency public information. The local Area Manager is the first Ontario Hydro person at the scene of the accident. The responding facility technical spokesperson is the second line of Corporate presence and the Ontario Hydro Corporate spokesperson is notified in case the accident is a media event; and 6) Ontario Hydro will respond to non-Hydro shipments of radioactive materials in terms of providing assistance, guidance and capability. However, the shipper is responsible

  17. Numerical study for enhancing the thermal conductivity of phase change material (PCM) storage using high thermal conductivity porous matrix

    International Nuclear Information System (INIS)

    Mesalhy, Osama; Lafdi, Khalid; Elgafy, Ahmed; Bowman, Keith

    2005-01-01

    In this paper, the melting process inside an irregular geometry filled with high thermal conductivity porous matrix saturated with phase change material PCM is investigated numerically. The numerical model is resting on solving the volume averaged conservation equations for mass, momentum and energy with phase change (melting) in the porous medium. The convection motion of the liquid phase inside the porous matrix is solved considering the Darcy, Brinkman and Forchiemer effects. A local thermal non-equilibrium assumption is considered due to the large difference in thermal properties between the solid matrix and PCM by applying a two energy equation model. The numerical code shows good agreement for pure PCM melting with another published numerical work. Through this study it is found that the presence of the porous matrix has a great effect on the heat transfer and melting rate of the PCM energy storage. Decreasing the porosity of the matrix increases the melting rate, but it also damps the convection motion. It is also found that the best technique to enhance the response of the PCM storage is to use a solid matrix with high porosity and high thermal conductivity

  18. 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

  19. Thermal response in van der Waals heterostructures

    KAUST Repository

    Gandi, Appala; Alshareef, Husam N.; Schwingenschlö gl, Udo

    2016-01-01

    We solve numerically the Boltzmann transport equations of the phonons and electrons to understand the thermoelectric response in heterostructures of M2CO2 (M: Ti, Zr, Hf) MXenes with transition metal dichalcogenide monolayers. Low frequency optical

  20. Tailored functional materials with controlled thermal expansion and excellent thermal conductivity

    International Nuclear Information System (INIS)

    Korb, G.; Sebo, P.

    1997-01-01

    Engineering materials are mainly used for structures. Therefore high-strength, stiffness and sufficient toughness are of prime importance. For a long time engineers thought first in terms of metals. Material scientists developed alloys tailored to the needs of industry. Ceramics are known to be brittle and therefore not suitable in the first place for structural application under stress. Polymers with their low modulus became attractive when reinforced with high-strength fibres. Composites processed by polymer, metal or ceramic matrices and high-strength reinforcements have been introduced into many sectors of industry. Engineering materials for structural applications fulfil a function: they withstand high stresses, temperatures, fatigue, creep etc. But usually we do not call them functional materials. Functional materials serve applications apart from classical engineering fields. Electricity conducting materials, semi conductors, memory alloys and many others are called functional materials. Because of the fact that the basic physical properties cannot be changed in single-phase materials, the combination of two and more materials with different properties lead to components with new and tailored properties. A few techniques for preparation are described as powder metallurgy, infiltration of prepegs and compaction of precoated fibres/particles. The lecture is focusing on carbon fibre/particle reinforced Metal Matrix Materials. The achievable properties, in particular the thermal conductivity originating from the base materials is depending on the orientation of the fibres and interfacial contacts in the composite. The carefully controlled expansion behaviour is the most important property to use the material as a heat sink in electronic assemblies. (author)

  1. Mechanical Testing of Carbon Based Woven Thermal Protection Materials

    Science.gov (United States)

    Pham, John; Agrawal, Parul; Arnold, James O.; Peterson, Keith; Venkatapathy, Ethiraj

    2013-01-01

    Three Dimensional Woven thermal protection system (TPS) materials are one of the enabling technologies for mechanically deployable hypersonic decelerator systems. These materials have been shown capable of serving a dual purpose as TPS and as structural load bearing members during entry and descent operations. In order to ensure successful structural performance, it is important to characterize the mechanical properties of these materials prior to and post exposure to entry-like heating conditions. This research focuses on the changes in load bearing capacity of woven TPS materials after being subjected to arcjet simulations of entry heating. Preliminary testing of arcjet tested materials [1] has shown a mechanical degradation. However, their residual strength is significantly more than the requirements for a mission to Venus [2]. A systematic investigation at the macro and microstructural scales is reported here to explore the potential causes of this degradation. The effects of heating on the sizing (an epoxy resin coating used to reduce friction and wear during fiber handling) are discussed as one of the possible causes for the decrease in mechanical properties. This investigation also provides valuable guidelines for margin policies for future mechanically deployable entry systems.

  2. Development of Processing Techniques for Advanced Thermal Protection Materials

    Science.gov (United States)

    Selvaduray, Guna; Cox, Michael; Srinivasan, Vijayakumar

    1997-01-01

    Thermal Protection Materials Branch (TPMB) has been involved in various research programs to improve the properties and structural integrity of the existing aerospace high temperature materials. Specimens from various research programs were brought into the analytical laboratory for the purpose of obtaining and refining the material characterization. The analytical laboratory in TPMB has many different instruments which were utilized to determine the physical and chemical characteristics of materials. Some of the instruments that were utilized by the SJSU students are: Scanning Electron Microscopy (SEM), Energy Dispersive X-ray analysis (EDX), X-ray Diffraction Spectrometer (XRD), Fourier Transform-Infrared Spectroscopy (FTIR), Ultra Violet Spectroscopy/Visible Spectroscopy (UV/VIS), Particle Size Analyzer (PSA), and Inductively Coupled Plasma Atomic Emission Spectrometer (ICP-AES). The above mentioned analytical instruments were utilized in the material characterization process of the specimens from research programs such as: aerogel ceramics (I) and (II), X-33 Blankets, ARC-Jet specimens, QUICFIX specimens and gas permeability of lightweight ceramic ablators. In addition to analytical instruments in the analytical laboratory at TPMB, there are several on-going experiments. One particular experiment allows the measurement of permeability of ceramic ablators. From these measurements, physical characteristics of the ceramic ablators can be derived.

  3. Studies on compatibility of energetic materials by thermal methods

    Directory of Open Access Journals (Sweden)

    Maria Alice Carvalho Mazzeu

    2010-04-01

    Full Text Available The chemical compatibility of explosives, pyrotechnics and propellants with those materials is studied to evaluate potential hazards when in contact with other materials during production, storage and handling. Compatibility can be studied by several thermal methods as DSC (differential scanning calorimetry, TG (Thermogravimetry, VST (Vacuum stability test and others. The test methods and well defined criteria are the most important elements when a compatibility study is being accomplished. In this paper, the compatibility of two very important high explosives used in ammunition, RDX (Cyclo-1,3,5-trimethylene-2,4,6-trinitramine and HMX (Cyclotetramethylene tetranitramine was studied with the materials: fluoroelastomer (Viton and powdered aluminum (Al, using DSC and VST methods. The criteria to judge the compatibility between materials is based on a standardization agreement (STANAG 4147, 2001, and the final conclusion is that explosives and this materials are compatible, but in DSC it was observed that the peak of decomposition temperature of the admixture of RDX with Al decreased in 3º C and another peak appeared after the decomposition peak.

  4. Thermal management analysis of a Li-ion battery cell using phase change material loaded with carbon fibers

    International Nuclear Information System (INIS)

    Samimi, Fereshteh; Babapoor, Aziz; Azizi, Mohammadmehdi; Karimi, Gholamreza

    2016-01-01

    High latent heat of PCMs (phase change materials) has made them as one of the most important materials for thermal management purposes. However, PCMs’ low thermal diffusivities could limit their use in applications which require fast thermal response. The goal of this study is to simulate thermal performance of a lithium ion battery cell in the presence of carbon fiber-PCM composites. The effect of carbon fiber loading within the PCM on thermal performance is studied and the results are compared with the experimental data. The results showed that the presence of carbon fibers increases the effective thermal conductivity of PCM and hence influences temperature distribution within the cell. PCM composites containing higher percentages of carbon fibers present a more uniform temperature distribution. The results showed that the minimum and maximum thermal conductivity enhancement of 85% and 155% respectively (105% on average). A reasonable agreement is obtained between the simulation results and the experimental data. - Highlights: • Phase change materials (PCMs) are used for thermal management purposes. • Effective thermal conductivity of PCMs can be enhanced by loading carbon fibers. • Thermal performance of a battery is studied in presence of carbon fiber loaded PCM. • The presence of carbon fibers in the PCM can improve Li-ion battery performance.

  5. Highly thermal conductive carbon fiber/boron carbide composite material

    International Nuclear Information System (INIS)

    Chiba, Akio; Suzuki, Yasutaka; Goto, Sumitaka; Saito, Yukio; Jinbo, Ryutaro; Ogiwara, Norio; Saido, Masahiro.

    1996-01-01

    In a composite member for use in walls of a thermonuclear reactor, if carbon fibers and boron carbide are mixed, since they are brought into contact with each other directly, boron is reacted with the carbon fibers to form boron carbide to lower thermal conductivity of the carbon fibers. Then, in the present invention, graphite or amorphous carbon is filled between the carbon fibers to provide a fiber bundle of not less than 500 carbon fibers. Further, the surface of the fiber bundle is coated with graphite or amorphous carbon to suppress diffusion or solid solubilization of boron to carbon fibers or reaction of them. Then, lowering of thermal conductivity of the carbon fibers is prevented, as well as the mixing amount of the carbon fiber bundles with boron carbide, a sintering temperature and orientation of carbon fiber bundles are optimized to provide a highly thermal conductive carbon fiber/boron carbide composite material. In addition, carbide or boride type short fibers, spherical graphite, and amorphous carbon are mixed in the boron carbide to prevent development of cracks. Diffusion or solid solubilization of boron to carbon fibers is reduced or reaction of them if the carbon fibers are bundled. (N.H.)

  6. Graphene nanocomposites as thermal interface materials for cooling energy devices

    Science.gov (United States)

    Dmitriev, A. S.; Valeev, A. R.

    2017-11-01

    The paper describes the technology of creating samples of graphene nanocomposites based on graphene flakes obtained by splitting graphite with ultrasound of high power. Graphene nanocomposites in the form of samples are made by the technology of weak sintering at high pressure (200-300 bar) and temperature up to 150 0 C, and also in the form of compositions with polymer matrices. The reflection spectra in the visible range and the near infrared range for the surface of nanocomposite samples are studied, the data of optical and electronic spectroscopy of such samples are givenIn addition, data on the electrophysical and thermal properties of the nanocomposites obtained are presented. Some analytical models of wetting and spreading over graphene nanocomposite surfaces have been constructed and calculated, and their effective thermal conductivity has been calculated and compared with the available experimental data. Possible applications of graphene nanocomposites for use as thermal interface materials for heat removal and cooling for power equipment, as well as microelectronics and optoelectronics devices are described.

  7. Effective Thermal Conductivity of Graphite Materials with Cracks

    Science.gov (United States)

    Pestchaanyi, S. E.; Landman, I. S.

    The dependence of effective thermal diffusivity on temperature caused by volumetric cracks is modelled for macroscopic graphite samples using the three-dimensional thermomechanics code Pegasus-3D. At high off-normal heat loads typical of the divertor armour, thermostress due to the anisotropy of graphite grains is much larger than that due to the temperature gradient. Numerical simulation demonstrated that the volumetric crack density both in fine grain graphites and in the CFC matrix depends mainly on the local sample temperature, not on the temperature gradient. This allows to define an effective thermal diffusivity for graphite with cracks. The results obtained are used to explain intense cracking and particle release from carbon based materials under electron beam heat load. Decrease of graphite thermal diffusivity with increase of the crack density explains particle release mechanism in the experiments with CFC where a clear energy threshold for the onset of particle release has been observed in J. Linke et al. Fusion Eng. Design, in press, Bazyler et al., these proceedings. Surface temperature measurement is necessary to calibrate the Pegasus-3D code for simulation of ITER divertor armour brittle destruction.

  8. Case for non-material specific thermal aging

    International Nuclear Information System (INIS)

    Bessey, R.L.

    1982-01-01

    The state-of-the-art model for accelerated thermal aging of components prior to seismic testing is the Arrhenius Model. The most pertinent independent variable in the equation is the minimum activation energy constant characterizing the component aging. With minor exceptions, existing measured values of the activation energy constant are inadequate as input to the model where a material specific aging acceleration factor is to be determined, for reasons described. The model itself is not very accurate. A case is made for a statistically justified minimum activation energy constant which is not material specific. The advantages of this are assessed. The major advantage is that this would provide the industry with a practical and uniform aging method that is consistent with the accuracy of the model

  9. Terahertz Computed Tomography of NASA Thermal Protection System Materials

    Science.gov (United States)

    Roth, D. J.; Reyes-Rodriguez, S.; Zimdars, D. A.; Rauser, R. W.; Ussery, W. W.

    2011-01-01

    A terahertz axial computed tomography system has been developed that uses time domain measurements in order to form cross-sectional image slices and three-dimensional volume renderings of terahertz-transparent materials. The system can inspect samples as large as 0.0283 cubic meters (1 cubic foot) with no safety concerns as for x-ray computed tomography. In this study, the system is evaluated for its ability to detect and characterize flat bottom holes, drilled holes, and embedded voids in foam materials utilized as thermal protection on the external fuel tanks for the Space Shuttle. X-ray micro-computed tomography was also performed on the samples to compare against the terahertz computed tomography results and better define embedded voids. Limits of detectability based on depth and size for the samples used in this study are loosely defined. Image sharpness and morphology characterization ability for terahertz computed tomography are qualitatively described.

  10. Thermally activated creep and fluidization in flowing disordered materials

    Science.gov (United States)

    Merabia, Samy; Detcheverry, François

    2016-11-01

    When submitted to a constant mechanical load, many materials display power law creep followed by fluidization. A fundamental understanding of these processes is still far from being achieved. Here, we characterize creep and fluidization on the basis of a mesoscopic viscoplastic model that includes thermally activated yielding events and a broad distribution of energy barriers, which may be lowered under the effect of a local deformation. We relate the creep exponent observed before fluidization to the width of barrier distribution and to the specific form of stress redistribution following yielding events. We show that Andrade creep is accompanied by local strain hardening driven by stress redistribution and find that the fluidization time depends exponentially on the applied stress. The simulation results are interpreted in the light of a mean-field analysis, and should help in rationalizing the creep phenomenology in disordered materials.

  11. Thermal transport in lithium ion batteries: An experimental investigation of interfaces and granular materials

    Science.gov (United States)

    Gaitonde, Aalok Jaisheela Uday

    Increasing usage and recent accidents due to lithium-ion (Li-ion) batteries exploding or catching on fire has inspired research on the characterization and thermal management of these batteries. In cylindrical 18650 cells, heat generated during the battery's charge/discharge cycle is poorly dissipated to the surrounding through its metallic case due to the poor thermal conductivity of the jelly roll, which is spirally wound with many interfaces between electrodes and the polymeric separator. This work presents a technique to measure the thermal conduction across the metallic case-plastic separator interface, which ultimately limits heat transfer out of the jelly roll. The polymeric separator and metallic case are harvested from discharged commercial 18650 battery cells for thermal testing. A miniaturized version of the reference bar method enables measurements of the interface resistance between the case and the separator by establishing a temperature gradient across a multilayer stack consisting of two reference layers of known thermal conductivity and the case-separator sample. The case-separator interfacial conductance is reported for a range of case temperatures and interface pressures. The mean thermal conductance across the case-separator interface is 670 +/- 275 W/(m2K) and no significant temperature or pressure dependence is observed. The effective thermal conductivity of the battery stack is measured to be 0.27 W/m/K and 0.32 W/m/K in linear and radial configurations, respectively. Many techniques for fabricating battery electrodes involve coating particles of the active materials on metallic current collectors. The impact of mechanical shearing on the resultant thermal properties of these packed particle beds during the fabrication process has not yet been studied. Thus, the final portion of this thesis designs and validates a measurement system to measure the effects of mechanical shearing on the thermal conductivity of packed granular beds. This system

  12. THERMLIB: a material property data library for thermal analysis of radioactive material transport casks

    International Nuclear Information System (INIS)

    Ikushima, Takeshi

    1998-03-01

    The paper describes an heat conduction data library and graphical program for analysis of radioactive material transport casks. More than 1000 of material data are compiled in the data library which was produced by Lawrence Livermore Laboratory. Thermal data such as, density, thermal conductivity, specific heat, phase-change or solid-state, transition temperature and latent heat have been tabulated. Using this data library, a data library processing program THERMLIB for thermal analysis has been developed. Main features of THERMLIB are as follows: (1) data have been tabulated against temperature, (2) more than 1000 material data are available, (3) it is capable of graphical representations for thermal data and (4) not only main frame computer but also work stations (OS UNIX) and personal computer (OS Windows) are available for use of THERMLIB. In the paper, brief illustration of data library is presented in the first section. The second section presents descriptions of structural data. The third section provides an user's guide for computer program and input data for THERMLIB. (author)

  13. THERMLIB: a material property data library for thermal analysis of radioactive material transport casks

    Energy Technology Data Exchange (ETDEWEB)

    Ikushima, Takeshi [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    The paper describes an heat conduction data library and graphical program for analysis of radioactive material transport casks. More than 1000 of material data are compiled in the data library which was produced by Lawrence Livermore Laboratory. Thermal data such as, density, thermal conductivity, specific heat, phase-change or solid-state, transition temperature and latent heat have been tabulated. Using this data library, a data library processing program THERMLIB for thermal analysis has been developed. Main features of THERMLIB are as follows: (1) data have been tabulated against temperature, (2) more than 1000 material data are available, (3) it is capable of graphical representations for thermal data and (4) not only main frame computer but also work stations (OS UNIX) and personal computer (OS Windows) are available for use of THERMLIB. In the paper, brief illustration of data library is presented in the first section. The second section presents descriptions of structural data. The third section provides an user`s guide for computer program and input data for THERMLIB. (author)

  14. The elastic response of composite materials

    International Nuclear Information System (INIS)

    Laws, N.

    1980-01-01

    The theory of linear elasticity is used to study the elastic response of composite materials. The main concern is the prediction of overall moduli. Some attention is paid to the problem of deciding upon when the idea of an overall modulus is meaningful. In addition it is shown how to calculate some rigorous bounds on the overall moduli, and some predictions of the self-consistent method are discussed. The paper mainly concentrates on isotropic dispersions of spheres, unidirectional fibre-reinforced materials and laminates. (author)

  15. Correlation of physical properties of ceramic materials with resistance to fracture by thermal shock

    Science.gov (United States)

    Lidman, W G; Bobrowsky, A R

    1949-01-01

    An analysis is made to determine which properties of materials affect their resistance to fracture by thermal stresses.From this analysis, a parameter is evaluated that is correlated with the resistance of ceramic materials to fracture by thermal shock as experimentally determined. This parameter may be used to predict qualitatively the resistance of a material to fracture by thermal shock. Resistance to fracture by thermal shock is shown to be dependent upon the following material properties: thermal conductivity, tensile strength, thermal expansion, and ductility modulus. For qualitative prediction of resistance of materials to fracture by thermal shock, the parameter may be expressed as the product of thermal conductivity and tensile strength divided by the product of linear coefficient of thermal expansion and ductility modulus of the specimen.

  16. Thermal segregation of asphalt material in road repair

    Directory of Open Access Journals (Sweden)

    Juliana Byzyka

    2017-08-01

    Full Text Available This paper presents results from a field study of asphaltic pavement patching operations performed by three different contractors working in a total of ten sites. It forms part of an ongoing research programme towards improving the performance of pothole repairs. Thermal imaging technology was used to record temperatures of the patching material throughout the entire exercise, from the stage of material collection, through transportation to repair site, patch forming, and compaction. Practical complications occurring during patch repairs were also identified. It was found that depending on the weather conditions, duration of the travel and poor insulation of the transported hot asphalt mix, its temperature can drop as high as 116.6 °C over the period that the reinstatement team travel to the site and prepare the patch. This impacting is on the durability and performance of the executed repairs. Cold spots on the asphalt mat and temperature differentials between the new hot-fill asphalt mix and existing pavement were also identified as poorly compacted areas that were prone to premature failure. For example, over the five-minute period, the temperature at one point reduced by 33% whereas the temperatures of nearby areas decreased by 65% and 71%. A return visit to the repair sites, three months later, revealed that locations where thermal segregation was noted, during the patching operation, had failed prematurely.

  17. Thermal durability of modified Synroc material as reactor fuel matrix

    International Nuclear Information System (INIS)

    Kikuchi, Akira; Kanazawa, Hiroyuki; Togashi, Yoshihiro; Matumoto, Seiichiro; Nishino, Yasuharu; Ohwada, Isao; Nakata, Masahito; Amano, Hidetoshi; Mitamura, Hisayoshi

    1994-08-01

    A Synroc, a polyphase titanate ceramics composed of three mineral phases (perovskite, hollandite and zirconolite), has an excellent performance of immobilization of high level nuclear waste. A working group in the Department of Hot Laboratories paid special attention to this merit and started a development study on a LWR fuel named 'Waste Disposal Possible (WDP) Fuel', which has the two functions of a reactor fuel and a waste form. The present paper mainly describes thermal durability of a modified Synroc material, which is essentially important for applying the material to a fuel matrix. The two kinds of Synroc specimens, designated 'SM' as modified and 'SB' as a reference, were prepared by hot-pressing and annealed at 1200degC to 1500degC for 30 min in air. Unexpected and peculiar spherical voids were observed in the specimen SM at 1400degC and 1500degC, which caused the specimen swelling. The formation of the voids depends significantly on the existence of spherical precipitates seen in the as-fabricated specimen including latent micropores with high pressure. On the other hand, the heat treatment at 1500degC formed additional new phases, designated 'Phase A' for the specimen SB and 'Phase X' for SM. Phase A is a decomposition product of hollandite and Phase X a reaction product of Phase A and perovskite in the spherical voids. Furthermore, additional information and thermal properties examined are presented in Appendix 1 and Appendix 2, respectively. It was recognized that the modified Synroc specimen SM had excellent thermal properties. (author)

  18. Model of optical phantoms thermal response upon irradiation with 975 nm dermatological laser

    Science.gov (United States)

    Wróbel, M. S.; Bashkatov, A. N.; Yakunin, A. N.; Avetisyan, Yu. A.; Genina, E. A.; Galla, S.; Sekowska, A.; Truchanowicz, D.; Cenian, A.; Jedrzejewska-Szczerska, M.; Tuchin, V. V.

    2018-04-01

    We have developed a numerical model describing the optical and thermal behavior of optical tissue phantoms upon laser irradiation. According to our previous studies, the phantoms can be used as substitute of real skin from the optical, as well as thermal point of view. However, the thermal parameters are not entirely similar to those of real tissues thus there is a need to develop mathematical model, describing the thermal and optical response of such materials. This will facilitate the correction factors, which would be invaluable in translation between measurements on skin phantom to real tissues, and gave a good representation of a real case application. Here, we present the model dependent on the data of our optical phantoms fabricated and measured in our previous preliminary study. The ambiguity between the modeling and the thermal measurements depend on lack of accurate knowledge of material's thermal properties and some exact parameters of the laser beam. Those parameters were varied in the simulation, to provide an overview of possible parameters' ranges and the magnitude of thermal response.

  19. Comparative analyses on dynamic performances of photovoltaic–thermal solar collectors integrated with phase change materials

    International Nuclear Information System (INIS)

    Su, Di; Jia, Yuting; Alva, Guruprasad; Liu, Lingkun; Fang, Guiyin

    2017-01-01

    Highlights: • The dynamic model of photovoltaic–thermal collector with phase change material was developed. • The performances of photovoltaic–thermal collector are performed comparative analyses. • The performances of photovoltaic–thermal collector with phase change material were evaluated. • Upper phase change material mode can improve performances of photovoltaic–thermal collector. - Abstract: The operating conditions (especially temperature) of photovoltaic–thermal solar collectors have significant influence on dynamic performance of the hybrid photovoltaic–thermal solar collectors. Only a small percentage of incoming solar radiation can be converted into electricity, and the rest is converted into heat. This heat leads to a decrease in efficiency of the photovoltaic module. In order to improve the performance of the hybrid photovoltaic–thermal solar collector, we performed comparative analyses on a hybrid photovoltaic–thermal solar collector integrated with phase change material. Electrical and thermal parameters like solar cell temperature, outlet temperature of air, electrical power, thermal power, electrical efficiency, thermal efficiency and overall efficiency are simulated and analyzed to evaluate the dynamic performance of the hybrid photovoltaic–thermal collector. It is found that the position of phase change material layer in the photovoltaic–thermal collector has a significant effect on the performance of the photovoltaic–thermal collector. The results indicate that upper phase change material mode in the photovoltaic–thermal collector can significantly improve the thermal and electrical performance of photovoltaic–thermal collector. It is found that overall efficiency of photovoltaic–thermal collector in ‘upper phase change material’ mode is 10.7% higher than that in ‘no phase change material’ mode. Further, for a photovoltaic–thermal collector with upper phase change material, it is verified that 3 cm

  20. Prediction of Thermal Transport Properties of Materials with Microstructural Complexity

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Youping

    2017-10-10

    This project aims at overcoming the major obstacle standing in the way of progress in dynamic multiscale simulation, which is the lack of a concurrent atomistic-continuum method that allows phonons, heat and defects to pass through the atomistic-continuum interface. The research has led to the development of a concurrent atomistic-continuum (CAC) methodology for multiscale simulations of materials microstructural, mechanical and thermal transport behavior. Its efficacy has been tested and demonstrated through simulations of dislocation dynamics and phonon transport coupled with microstructural evolution in a variety of materials and through providing visual evidences of the nature of phonon transport, such as showing the propagation of heat pulses in single and polycrystalline solids is partially ballistic and partially diffusive. In addition to providing understanding on phonon scattering with phase interface and with grain boundaries, the research has contributed a multiscale simulation tool for understanding of the behavior of complex materials and has demonstrated the capability of the tool in simulating the dynamic, in situ experimental studies of nonequilibrium transient transport processes in material samples that are at length scales typically inaccessible by atomistically resolved methods.

  1. A Study on the Interaction Mechanism between Thermal Radiation and Materials

    Institute of Scientific and Technical Information of China (English)

    Dehong XIA; Tao YU; Chuangu WU; Qingqing CHANG; Honglei JIAO

    2005-01-01

    From the viewpoint of field synergy principle and dipole radiation theory, the interaction between the incident thermal radiation wave and materials is analyzed to reveal the mechanism of selective absorption of incident thermal radiation. It is shown that the frequency of the incident thermal radiation and the damping constant of damping oscillators in materials are of vital importance for the thermal radiation properties (reflectivity, absorptivity, transmissivity, etc.) of materials.

  2. The constitutive response of three solder materials

    International Nuclear Information System (INIS)

    Perez-Bergquist, Alejandro G.; Cao Fang; Perez-Bergquist, Sara J.; Lopez, Mike F.; Trujillo, Carl P.; Cerreta, Ellen K.; Gray, George T.

    2012-01-01

    Highlights: ► The full constitutive response of three solder materials. ► Test temperatures from −196 °C to 60 °C and strain rates from 10 −3 to >10 3 s −1 . ► Substitutes for leaded solders from a mechanical/microstructural properties view. - Abstract: As increasing worldwide demand for portable consumer electronics drives development of smaller, faster, more powerful electronic devices, components in these devices must become smaller, more precise, and more robust. Often, failure of these devices comes as a result of failure of the package (i.e. when a mobile phone is dropped) and specifically comes as a result of failure of solder interconnects. As a result, stronger more reliable solder materials are needed. In this paper, the constitutive responses of three solder materials (Sn63Pb37, Sn62Pb36Ag2, and Sn96.5Ag3Cu0.5) are analyzed as a function of temperature (−196 °C to 60 °C) and strain rate (10 −3 to >10 3 s −1 ). The lead-free Sn96.5Ag3Cu0.5 possessed the highest yield stress of the three solders at all tested strain rates and temperatures, and all solder microstructures which displayed a mechanical response that was sensitive to temperature exhibited grain coarsening with increasing plastic strain, even at room temperature.

  3. The constitutive response of three solder materials

    Energy Technology Data Exchange (ETDEWEB)

    Perez-Bergquist, Alejandro G., E-mail: alexpb@lanl.gov [Materials Science and Technology Division, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, NM 87545 (United States); Cao Fang [Exxon Mobil Research and Engineering Company, Annadale, NJ 08801 (United States); Perez-Bergquist, Sara J.; Lopez, Mike F.; Trujillo, Carl P.; Cerreta, Ellen K.; Gray, George T. [Materials Science and Technology Division, Los Alamos National Laboratory, Mail Stop G755, Los Alamos, NM 87545 (United States)

    2012-05-25

    Highlights: Black-Right-Pointing-Pointer The full constitutive response of three solder materials. Black-Right-Pointing-Pointer Test temperatures from -196 Degree-Sign C to 60 Degree-Sign C and strain rates from 10{sup -3} to >10{sup 3} s{sup -1}. Black-Right-Pointing-Pointer Substitutes for leaded solders from a mechanical/microstructural properties view. - Abstract: As increasing worldwide demand for portable consumer electronics drives development of smaller, faster, more powerful electronic devices, components in these devices must become smaller, more precise, and more robust. Often, failure of these devices comes as a result of failure of the package (i.e. when a mobile phone is dropped) and specifically comes as a result of failure of solder interconnects. As a result, stronger more reliable solder materials are needed. In this paper, the constitutive responses of three solder materials (Sn63Pb37, Sn62Pb36Ag2, and Sn96.5Ag3Cu0.5) are analyzed as a function of temperature (-196 Degree-Sign C to 60 Degree-Sign C) and strain rate (10{sup -3} to >10{sup 3} s{sup -1}). The lead-free Sn96.5Ag3Cu0.5 possessed the highest yield stress of the three solders at all tested strain rates and temperatures, and all solder microstructures which displayed a mechanical response that was sensitive to temperature exhibited grain coarsening with increasing plastic strain, even at room temperature.

  4. A review of phase change materials for vehicle component thermal buffering

    International Nuclear Information System (INIS)

    Jankowski, Nicholas R.; McCluskey, F. Patrick

    2014-01-01

    Highlights: • A review of latent heat thermal energy storage for vehicle thermal load leveling. • Examined vehicle applications with transient thermal profiles from 0 to 800 °C. • >700 materials from over a dozen material classes examined for the applications. • Recommendations made for future application of high power density materials. - Abstract: The use of latent heat thermal energy storage for thermally buffering vehicle systems is reviewed. Vehicle systems with transient thermal profiles are classified according to operating temperatures in the range of 0–800 °C. Thermal conditions of those applications are examined relative to their impact on thermal buffer requirements, and prior phase change thermal enhancement studies for these applications are discussed. In addition a comprehensive overview of phase change materials covering the relevant operating range is given, including selection criteria and a detailed list of over 700 candidate materials from a number of material classes. Promising material candidates are identified for each vehicle system based on system temperature, specific and volumetric latent heat, and thermal conductivity. Based on the results of previous thermal load leveling efforts, there is the potential for making significant improvements in both emissions reduction and overall energy efficiency by further exploration of PCM thermal buffering on vehicles. Recommendations are made for further material characterization, with focus on the need for improved data for metallic and solid-state phase change materials for high energy density applications

  5. Kinetically controlled thermal response of beta2-microglobulin amyloid fibrils.

    Science.gov (United States)

    Sasahara, Kenji; Naiki, Hironobu; Goto, Yuji

    2005-09-23

    Calorimetric measurements were carried out using a differential scanning calorimeter in the temperature range from 10 to 120 degrees C for characterizing the thermal response of beta2-microglobulin amyloid fibrils. The thermograms of amyloid fibril solution showed a remarkably large decrease in heat capacity that was essentially released upon the thermal unfolding of the fibrils, in which the magnitude of negative heat capacity change was not explicable in terms of the current accessible surface area model of protein structural thermodynamics. The heat capacity-temperature curve of amyloid fibrils prior to the fibril unfolding exhibited an unusual dependence on the fibril concentration and the heating rate. Particularly, the heat needed to induce the thermal response was found to be linearly dependent on the heating rate, indicating that its thermal response is under a kinetic control and precluding the interpretation in terms of equilibrium thermodynamics. Furthermore, amyloid fibrils of amyloid beta peptides also exhibited a heating rate-dependent exothermic process before the fibril unfolding, indicating that the kinetically controlled thermal response may be a common phenomenon to amyloid fibrils. We suggest that the heating rate-dependent negative change in heat capacity is coupled to the association of amyloid fibrils with characteristic hydration pattern.

  6. Biomimetic materials for controlling bone cell responses.

    Science.gov (United States)

    Drevelle, Olivier; Faucheux, Nathalie

    2013-01-01

    Bone defects that cannot "heal spontaneously during life" will become an ever greater health problem as populations age. Harvesting autografts has several drawbacks, such as pain and morbidity at both donor and acceptor sites, the limited quantity of material available, and frequently its inappropriate shape. Researchers have therefore developed alternative strategies that involve biomaterials to fill bone defects. These biomaterials must be biocompatible and interact with the surrounding bone tissue to allow their colonization by bone cells and blood vessels. The latest generation biomaterials are not inert; they control cell responses like adhesion, proliferation and differentiation. These biomaterials are called biomimetic materials. This review focuses on the development of third generation materials. We first briefly describe the bone tissue with its cells and matrix, and then how bone cells interact with the extracellular matrix. The next section covers the materials currently used to repair bone defects. Finally, we describe the strategies employed to modify the surface of materials, such as coating with hydroxyapatite and grafting biomolecules.

  7. Spin crossover-induced colossal positive and negative thermal expansion in a nanoporous coordination framework material.

    Science.gov (United States)

    Mullaney, Benjamin R; Goux-Capes, Laurence; Price, David J; Chastanet, Guillaume; Létard, Jean-François; Kepert, Cameron J

    2017-10-20

    External control over the mechanical function of materials is paramount in the development of nanoscale machines. Yet, exploiting changes in atomic behaviour to produce controlled scalable motion is a formidable challenge. Here, we present an ultra-flexible coordination framework material in which a cooperative electronic transition induces an extreme abrupt change in the crystal lattice conformation. This arises due to a change in the preferred coordination character of Fe(II) sites at different spin states, generating scissor-type flexing of the crystal lattice. Diluting the framework with transition-inactive Ni(II) sites disrupts long-range communication of spin state through the lattice, producing a more gradual transition and continuous lattice movement, thus generating colossal positive and negative linear thermal expansion behaviour, with coefficients of thermal expansion an order of magnitude greater than previously reported. This study has wider implications in the development of advanced responsive structures, demonstrating electronic control over mechanical motion.

  8. Materials Compositions for Lithium Ion Batteries with Extended Thermal Stability

    Science.gov (United States)

    Kalaga, Kaushik

    Advancements in portable electronics have generated a pronounced demand for rechargeable energy storage devices with superior capacity and reliability. Lithium ion batteries (LIBs) have evolved as the primary choice of portable power for several such applications. While multiple variations have been developed, safety concerns of commercial technologies limit them to atmospheric temperature operability. With several niche markets such as aerospace, defense and oil & gas demanding energy storage at elevated temperatures, there is a renewed interest in developing rechargeable batteries that could survive temperatures beyond 100°C. Instability of critical battery components towards extreme thermal and electrochemical conditions limit their usability at high temperatures. This study deals with developing material configurations for LIB components to stabilize them at such temperatures. Flammable organic solvent based electrolytes and low melting polymer based separators have been identified as the primary bottleneck for LIBs to survive increasing temperature. Furthermore, thermally activated degradation processes in oxide based electrodes have been identified as the reason for their limited lifetime. A quasi-solid composite comprising of room temperature ionic liquids (RTILs) and Clay was developed as an electrolyte/separator hybrid and tested to be stable up to 120°C. These composites facilitate complete reversible Li intercalation in lithium titanate (LTO) with a stable capacity of 120 mAh g-1 for several cycles of charge and discharge while simultaneously resisting severe thermal conditions. Modified phosphate based electrodes were introduced as a reliable alternative for operability at high temperatures in this study. These systems were shown to deliver stable reversible capacity for numerous charge/discharge cycles at elevated temperatures. Higher lithium intercalation potential of the developed cathode materials makes them interesting candidates for high voltage

  9. 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.

  10. Thermally modulated nano-trampoline material as smart skin for gas molecular mass detection

    Science.gov (United States)

    Xia, Hua

    2012-06-01

    Conventional multi-component gas analysis is based either on laser spectroscopy, laser and photoacoustic absorption at specific wavelengths, or on gas chromatography by separating the components of a gas mixture primarily due to boiling point (or vapor pressure) differences. This paper will present a new gas molecular mass detection method based on thermally modulated nano-trampoline material as smart skin for gas molecular mass detection by fiber Bragg grating-based gas sensors. Such a nanomaterial and fiber Bragg grating integrated sensing device has been designed to be operated either at high-energy level (highly thermal strained status) or at low-energy level (low thermal strained status). Thermal energy absorption of gas molecular trigs the sensing device transition from high-thermal-energy status to low-thermal- energy status. Experiment has shown that thermal energy variation due to gas molecular thermal energy absorption is dependent upon the gas molecular mass, and can be detected by fiber Bragg resonant wavelength shift with a linear function from 17 kg/kmol to 32 kg/kmol and a sensitivity of 0.025 kg/kmol for a 5 micron-thick nano-trampoline structure and fiber Bragg grating integrated gas sensing device. The laboratory and field validation data have further demonstrated its fast response characteristics and reliability to be online gas analysis instrument for measuring effective gas molecular mass from single-component gas, binary-component gas mixture, and multi-gas mixture. The potential industrial applications include fouling and surge control for gas charge centrifugal compressor ethylene production, gas purity for hydrogen-cooled generator, gasification for syngas production, gasoline/diesel and natural gas fuel quality monitoring for consumer market.

  11. Evaluation of heat sink materials for thermal management of lithium batteries

    Science.gov (United States)

    Dimpault-Darcy, E. C.; Miller, K.

    Aluminum, neopentyl glycol (NPG), and resins FT and KT are evaluated theoretically and experimentally as heat sink materials for lithium battery packs. The thermal performances of the two resins are compared in a thermal vacuum experiment. As solutions to the sublimation property were not immediately apparent, a theoretical comparison of the thermal performance of NPG versus KT, Al, and no material, is presented.

  12. Evaluation of heat sink materials for thermal management of lithium batteries

    Science.gov (United States)

    Dimpault-Darcy, E. C.; Miller, K.

    1988-01-01

    Aluminum, neopentyl glycol (NPG), and resins FT and KT are evaluated theoretically and experimentally as heat sink materials for lithium battery packs. The thermal performances of the two resins are compared in a thermal vacuum experiment. As solutions to the sublimation property were not immediately apparent, a theoretical comparison of the thermal performance of NPG versus KT, Al, and no material, is presented.

  13. Thermal sensation and thermophysiological responses with metabolic step-changes

    DEFF Research Database (Denmark)

    Goto, Tomonobu; Toftum, Jørn; deDear, Richard

    2006-01-01

    at sedentary activity. In a second experimental series, subjects alternated between rest and exercise as well as between exercise at different intensities at two temperature levels. Measurements comprised skin and oesophageal temperatures, heart rate and subjective responses. Thermal sensation started to rise....... The sensitivity of thermal sensation to changes in core temperature was higher for activity down-steps than for up-steps. A model was proposed that estimates transient thermal sensation after metabolic step-changes. Based on predictions by the model, weighting factors were suggested to estimate a representative...... average metabolic rate with varying activity levels, e.g. for the prediction of thermal sensation by steady-state comfort models. The activity during the most recent 5 min should be weighted 65%, during the prior 10-5 min 25% and during the prior 20-10 min 10%....

  14. Ceramic materials with low thermal conductivity and low coefficients of thermal expansion

    Science.gov (United States)

    Brown, Jesse; Hirschfeld, Deidre; Liu, Dean-Mo; Yang, Yaping; Li, Tingkai; Swanson, Robert E.; Van Aken, Steven; Kim, Jin-Min

    1992-01-01

    Compositions having the general formula (Ca.sub.x Mg.sub.1-x)Zr.sub.4 (PO.sub.4).sub.6 where x is between 0.5 and 0.99 are produced by solid state and sol-gel processes. In a preferred embodiment, when x is between 0.5 and 0.8, the MgCZP materials have near-zero coefficients of thermal expansion. The MgCZPs of the present invention also show unusually low thermal conductivities, and are stable at high temperatures. Macrostructures formed from MgCZP are useful in a wide variety of high-temperature applications. In a preferred process, calcium, magnesium, and zirconium nitrate solutions have their pH adjusted to between 7 and 9 either before or after the addition of ammonium dihydrogen phosphate. After dehydration to a gel, and calcination at temperatures in excess of 850.degree. C. for approximately 16 hours, single phase crystalline MgCZP powders with particle sizes ranging from approximately 20 nm to 50 nm result. The MgCZP powders are then sintered at temperatures ranging from 1200.degree. C. to 1350.degree. C. to form solid macrostructures with near-zero bulk coefficients of thermal expansion and low thermal conductivities. Porous macrostructures of the MgCZP powders of the present invention are also formed by combination with a polymeric powder and a binding agent, and sintering at high temperatures. The porosity of the resulting macrostructures can be adjusted by varying the particle size of the polymeric powder used.

  15. Effects of thermal underwear on thermal and subjective responses in winter.

    Science.gov (United States)

    Choi, Jeong-Wha; Lee, Joo-Young; Kim, So-Young

    2003-01-01

    This study was conducted to obtain basic data in improving the health of Koreans, saving energy and protecting environments. This study investigated the effects of wearing thermal underwear for keeping warm in the office in winter where temperature is not as low as affecting work efficiency, on thermoregulatory responses and subjective sensations. In order to create an environment where every subject feels the same thermal sensation, two experimental conditions were selected through preliminary experiments: wearing thermal underwear in 18 degrees C air (18-condition) and not wearing thermal underwear in 23 degrees C air (23-condition). Six healthy male students participated in this study as experiment subjects. Measurement items included rectal temperature (T(re)), skin temperature (T(sk)), clothing microclimate temperature (T(cm)), thermal sensation and thermal comfort. The results are as follows: (1) T(re) of all subjects was maintained constant at 37.1 degrees C under both conditions, indicating no significant differences. (2) (T)(sk) under the 18-condition and the 23-condition were 32.9 degrees C and 33.7 degrees C, respectively, indicating a significant level of difference (pcomfortable under both conditions. It was found (T)(sk) decreased due to a drop in the skin temperature of hands and feet, and the subjects felt cooler wearing only one layer of normal thermal underwear at 18 degrees C. Yet, the thermal comfort level, T(re) and T(cm) of chest part under the 18-condition were the same as those under the 23-condition. These results show that the same level of comfort, T(re) and T(cm) can be maintained as that of an environment about 5 degrees C higher in the office in winter, by wearing one layer of thermal underwear. In this regard, this study suggests that lowering indoor temperature by wearing thermal underwear in winter can contribute to saving energy and improving health.

  16. Nociceptive responses to thermal and mechanical stimulations in awake pigs

    DEFF Research Database (Denmark)

    di Giminiani, Pierpaolo; Petersen, Lars Jelstrup; Herskin, Mette S.

    2013-01-01

    body sizes (30 and 60 kg) were exposed to thermal (CO(2) laser) and mechanical (pressure application measurement device) stimulations to the flank and the hind legs in a balanced order. The median response latency and the type of behavioural response were recorded. RESULTS: Small pigs exhibited...... animal studies in a large species require further examination. This manuscript describes the initial development of a porcine model of cutaneous nociception and focuses on interactions between the sensory modality, body size and the anatomical location of the stimulation site. METHODS: Pigs of different...... significantly lower pain thresholds (shorter latency to response) than large pigs to thermal and mechanical stimulations. Stimulations at the two anatomical locations elicited very distinct sets of behavioural responses, with different levels of sensitivity between the flank and the hind legs. Furthermore...

  17. Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials

    National Research Council Canada - National Science Library

    Zhu, Dongming

    2004-01-01

    .... In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz...

  18. Advanced Oxide Material Systems for 1650 Deg. C Thermal/Environmental Barrier Coating Applications

    National Research Council Canada - National Science Library

    Zhu, Dongming; Fox, Dennis S; Bansal, Narottam P; Miller, Robert A

    2004-01-01

    ... systems under engine high-heat-flux and severe thermal cycling conditions. In this report, the thermal conductivity and water vapor stability of selected candidate hafnia-, pyrochlore-, and magnetoplumbite-based TEBC materials are evaluated...

  19. Simple method of calculating the transient thermal performance of composite material and its applicable condition

    Institute of Scientific and Technical Information of China (English)

    张寅平; 梁新刚; 江忆; 狄洪发; 宁志军

    2000-01-01

    Degree of mixing of composite material is defined and the condition of using the effective thermal diffusivity for calculating the transient thermal performance of composite material is studied. The analytical result shows that for a prescribed precision of temperature, there is a condition under which the transient temperature distribution in composite material can be calculated by using the effective thermal diffusivity. As illustration, for the composite material whose temperatures of both ends are constant, the condition is presented and the factors affecting the relative error of calculated temperature of composite materials by using effective thermal diffusivity are discussed.

  20. Response of neutron-irradiated RPV steels to thermal annealing

    International Nuclear Information System (INIS)

    Iskander, S.K.; Sokolov, M.A.; Nanstad, R.K.

    1997-01-01

    One of the options to mitigate the effects of irradiation on reactor pressure vessels (RPVs) is to thermally anneal them to restore the fracture toughness properties that have been degraded by neutron irradiation. This paper summarizes experimental results of work performed at the Oak Ridge National Laboratory (ORNL) to study the annealing response of several irradiated RPV steels

  1. Thermal Upgrading of 9977 Radioactive Material (Ram) Type B Package

    International Nuclear Information System (INIS)

    Gupta, N.; Abramczyk, G.

    2012-01-01

    The 9977 package is a radioactive material package that was originally certified to ship Heat Sources and RTG contents up to 19 watts and it is now being reviewed to significantly expand its contents in support of additional DOE missions. Thermal upgrading will be accomplished by employing stacked 3013 containers, a 3013 aluminum spacer and an external aluminum sleeve for enhanced heat transfer. The 7th Addendum to the original 9977 package Safety Basis Report describing these modifications is under review for the DOE certification. The analyses described in this paper show that this well-designed and conservatively analyzed package can be upgraded to carry contents with decay heat up to 38 watts with some simple design modifications. The Model 9977 package has been designed as a replacement for the Department of Transportation (DOT) Fissile Specification 6M package. The 9977 package is a very versatile Type B package which is certified to transport and store a wide spectrum of radioactive materials. The package was analyzed quite conservatively to increase its usefulness and store different payload configurations. Its versatility is evident from several daughter packages such as the 9978 and H1700, and several addendums where the payloads have been modified to suit the Shipper's needs without additional testing.

  2. Porous Materials from Thermally Activated Kaolinite: Preparation, Characterization and Application

    Directory of Open Access Journals (Sweden)

    Jun Luo

    2017-06-01

    Full Text Available In the present study, porous alumina/silica materials were prepared by selective leaching of silicon/aluminum constituents from thermal-activated kaolinite in inorganic acid or alkali liquor. The correlations between the characteristics of the prepared porous materials and the dissolution properties of activated kaolinite were also investigated. The results show that the specific surface area (SSA of porous alumina/silica increases with silica/alumina dissolution, but without marked change of the BJH pore size. Furthermore, change in pore volume is more dependent on activation temperature. The porous alumina and silica obtained from alkali leaching of kaolinite activated at 1150 °C for 15 min and acid leaching of kaolinite activated at 850 °C for 15 min are mesoporous, with SSAs, BJH pore sizes and pore volumes of 55.8 m2/g and 280.3 m2/g, 6.06 nm and 3.06 nm, 0.1455 mL/g and 0.1945 mL/g, respectively. According to the adsorption tests, porous alumina has superior adsorption capacities for Cu2+, Pb2+ and Cd2+ compared with porous silica and activated carbon. The maximum capacities of porous alumina for Cu2+, Pb2+ and Cd2+ are 134 mg/g, 183 mg/g and 195 mg/g, respectively, at 30 °C.

  3. Thermal energy storage characteristics of bentonite-based composite PCMs with enhanced thermal conductivity as novel thermal storage building materials

    International Nuclear Information System (INIS)

    Sarı, Ahmet

    2016-01-01

    Graphical abstract: In this work, novel bentonite-based and form-stable composite phase change materials (Bb-FSPCMs) were produced for LHTES in buildings by impregnation of CA, PEG600, DD and HD with bentonite clay. The microstructures of the compatibility of the Bb-FSPCMs were by using SEM and FT-IR techniques. The DSC results indicated that the produced Bb-FSPCMs composites had suitable phase change temperature of 4–30 °C and good latent heat capacity between 38 and 74 J/g. The TG results demonstrated that all of the fabricated Bb-FSPCMs had good thermal resistance. The Bb-FSPCMs maintained their LHTES properties even after 1000 heating–cooling cycling. The total heating times of the prepared Bb-FSPCMs were reduced noticeably due to their enhanced thermal conductivity after EG (5 wt%) addition. - Highlights: • Bb-FSPCMs were produced by impregnation of CA, PEG600, DD and HD with bentonite. • DSC analysis indicated that Bb-FSPCMs had melting temperature in range of 4–30 °C. • DSC analysis also showed that Bb-FSPCMs had latent heat between 38 and 74 J/g. • The TG analysis demonstrated that Bb-FSPCMs had good thermal resistance. • Thermal conductivity of Bb-FSPCMs were enhanced noticeably with EG (5 wt%) addition. - Abstract: In this work, for latent heat thermal energy storage (LHTES) applications in buildings, bentonite-based form-stable composite phase change materials (Bb-FSPCMs) were produced by impregnation of capric acid (CA), polyethylene glycol (PEG600), dodecanol (DD) and heptadecane (HD) into bentonite clay. The morphological characterization results obtained by scanning electron microscopy (SEM) showed that the bentonite acted as good structural barrier for the organic PCMs homogenously dispersed onto its surface and interlayers. The chemical investigations made by using fourier transform infrared (FT-IR) technique revealed that the attractions between the components of the composites was physical in nature and thus the PCMs were hold

  4. Thermal properties and thermal reliability of eutectic mixtures of some fatty acids as latent heat storage materials

    International Nuclear Information System (INIS)

    Sari, Ahmet; Sari, Hayati; Oenal, Adem

    2004-01-01

    The present study deals with two subjects. The first one is to determine the thermal properties of lauric acid (LA)-stearic acid (SA), myristic acid (MA)-palmitic acid (PA) and palmitic acid (PA)-stearic acid (SA) eutectic mixtures as latent heat storage material. The properties were measured by the differential scanning calorimetry (DSC) analysis technique. The second one is to study the thermal reliability of these materials in view of the change in their melting temperatures and latent heats of fusion with respect to repeated thermal cycles. For this aim, the eutectic mixtures were subjected to 360 repeated melt/freeze cycles, and their thermal properties were measured after 0, 90,180 and 360 thermal cycles by the technique of DSC analysis. The DSC thermal analysis results show that the binary systems of LA-SA in the ratio of 75.5:24.5 wt.%, MA-PA in the ratio of 58:42 wt.% and PA-SA in the ratio of 64.2:35.8 wt.% form eutectic mixtures with melting temperatures of 37.0, 42.60 and 52.30 deg. C and with latent heats of fusion of 182.7, 169.7 and 181.7 J g -1 , respectively. These thermal properties make them possible for heat storage in passive solar heating applications with respect to climate conditions. The accelerated thermal cycle tests indicate that the changes in the melting temperatures and latent heats of fusion of the studied eutectic mixtures are not regular with increasing number of thermal cycles. However, these materials, latent heat energy storage materials, have good thermal reliability in terms of the change in their thermal properties with respect to thermal cycling for about a one year utility period

  5. 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...

  6. Thermal analysis of a double layer phase change material floor

    International Nuclear Information System (INIS)

    Jin Xing; Zhang Xiaosong

    2011-01-01

    Phase change materials (PCMs) can be used to shift the cooling or heating load from the peak period to the off-peak period. In this paper, a new double layer phase change material (PCM) floor is put forward. The two layers of PCM have different melting temperature. The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. According to the numerical model built in this paper, the thermal performances of the floor are analyzed. The results show that the optimal melting temperatures of PCMs exist. The fluctuations of the floor surface temperatures and the heat fluxes will be reduced and the system still can provide a certain amount of heat or cold energy after the heat pump or chiller has been turned off for a long time. Compared to the floor without PCM, the energy released by the floor with PCM in peak period will be increased by 41.1% and 37.9% during heating and cooling when the heat of fusion of PCM is 150 kJ/kg. - Highlights: → A new double layer phase change material floor is put forward. → The system is used to store heat or cold energy in the off-peak period and release them in the peak period during heating or cooling. → The optimal melting temperatures of PCMs in the system exist. → The heat and cold energy released by the floor with PCM in peak period can be increased by 41.1% and 37.9%.

  7. Method of thermal reprocessing of hydrocarbon raw material

    Energy Technology Data Exchange (ETDEWEB)

    Feygin, Ye.A.; Bakhshiyan, Ts.A.; Barashkov, R.Ya.; Kazhdan, A.Z.; Raud, E.A.; Umanchik, N.P.

    1979-09-30

    In the method of thermal reprocessing of hydrocarbon raw material, to raise the efficiency of the process the heat exchange is done using a heat carrier in the form of a melt of metals or their salts, circulating in a closed system with a forced heating source in sequence through the pyrolysis zone, cooling zone, and heating zone. For example, the benzine fraction with initial boiling temperatures of 80-186 degrees C, together with steam, in the amount of 20% at 20 degrees C and pressure of 2 atmospheres, goes to the heating zone. Liquid Li goes there from the cooling zone through a closed circuit at 749 degrees C. The benzine, evaporated and heated to 300 degrees C, together with the melt, go to the pyrolysis zone, where the benzine is heated through the wall by the liquid Li coming from the heat carrier heating zone at 1000 degrees C. From the pyrolysis zone, the products, containing 41% C/sub 2/H/sub 4/, 15% C/sub 3/H/sub 6/ and 21% heavy fractions, go with the melt at 900 degrees C to the cooling zone, where they are cooled through the wall to 400 degrees C by the circulating liquid Li. The Li temperature at the entry into the cooling zone is 350 degrees C. The degree of raw material conversion is over 98%; the melt/raw material weight ratio is 0.2. Using this method enables a reduction in the pyrolysis zone from 80 to 8 m and the cooling zone area from 13 to 0.6 m/sup 2/ compared with the existing one, and transition from a multiple-tube cooling zone design to a tube one. The volume of the furnace unit is reduced from 500 to 10 m/sup 3/; the C/sub 2/H/sub 4/ yield is increased from 26-28 to 40-42%.

  8. Simultaneous Determination of Thermal Conductivity and Thermal Diffusivity of Food and Agricultural Materials Using a Transient Plane-Source Method

    Science.gov (United States)

    Thermal conductivity and thermal diffusivity are two important physical properties essential for designing any food engineering processes. Recently a new transient plane-source method was developed to measure a variety of materials, but its application in foods has not been documented. Therefore, ...

  9. Determination of the Local Thermal Conductivity of Functionally Graded Materials by a Laser Flash Method

    DEFF Research Database (Denmark)

    Zajas, Jan Jakub; Heiselberg, Per

    2013-01-01

    Determination of thermal conductivity of construction materials is essential to estimate their insulation capabilities. In most cases, homogenous materials are used and well developed methods exist for measurements of their thermal conductivity. The task becomes more challenging when dealing...... by scanning them point by point and determining the thermal conductivity as a function of the spatial dimensions. The method proves to be repeatable and of reasonable accuracy and can be used to determine the local thermal properties on a scale of millimeters. In this study, the method was successfully...... applied to create a map of thermal conductivity of a functionally graded material sample....

  10. Thermal comfort, physiological responses and performance during exposure to a moderate temperature drift

    DEFF Research Database (Denmark)

    Schellen, Lisje; van Marken Lichtenbelt, Wouter; de Wit, Martin

    2008-01-01

    The objective of this research was to study the effects of a moderate temperature drift on human thermal comfort, physiological responses, productivity and performance. A dynamic thermophysiological model was used to examine the possibility of simulating human thermal responses and thermal comfort...... temperature corresponding with a neutral thermal sensation (control situation). During the experiments both physiological responses and thermal sensation were measured. Productivity and performance were assessed with a ‘Remote Performance Measurement’ (RPM) method. Physiological and thermal sensation data...

  11. Early inflammatory response in rat brain after peripheral thermal injury.

    Science.gov (United States)

    Reyes, Raul; Wu, Yimin; Lai, Qin; Mrizek, Michael; Berger, Jamie; Jimenez, David F; Barone, Constance M; Ding, Yuchuan

    2006-10-16

    Previous studies have shown that the cerebral complications associated with skin burn victims are correlated with brain damage. The aim of this study was to determine whether systemic thermal injury induces inflammatory responses in the brain. Sprague Dawley rats (n=28) were studied in thermal injury and control groups. Animals from the thermal injury (n=14) and control (n=14) group were anesthetized and submerged to the neck vertically in 85 degrees C water for 6 s producing a third degree burn affecting 60-70% of the animal body surface area. The controls were submerged in 37 degrees C water for 6 s. Early expression of tumor necrosis factor-alpha (TNF-alpha), interleukin 1-beta (IL-1beta), and intracellular cell adhesion molecules (ICAM-1) protein levels in serum were determined at 3 (n=7) and 7 h (n=7) by enzyme-linked immunoabsorbent assay (ELISA). mRNA of TNF-alpha, IL-1beta, and ICAM-1 in the brain was measured at the same time points with a real-time reverse transcriptase-polymerase chain reaction (RT-PCR). An equal animal number was used for controls. Systemic inflammatory responses were demonstrated by dramatic up-regulations (5-50 fold) of TNF-alpha, IL-1beta, and ICAM-1 protein level in serum at 7 h after the thermal injury. However, as early as 3 h after peripheral thermal injury, a significant increase (3-15 fold) in mRNA expression of TNF-alpha, IL-1beta and ICAM-1 was observed in brain homogenates, with increased levels remaining at 7 h after injury. This study demonstrated an early inflammatory response in the brain after severe peripheral thermal injury. The cerebral inflammatory reaction was associated with expression of systemic cytokines and an adhesion molecule.

  12. Effect of carbon nanospheres on shape stabilization and thermal behavior of phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Mehrali, Mohammad; Tahan Latibari, Sara; Mehrali, Mehdi; Mahlia, Teuku Meurah Indra; Cornelis Metselaar, Hendrik Simon

    2014-01-01

    Highlights: • Introducing novel form-stable PCM of stearic acid (SA)/carbon nanospheres (CNSs). • The highest stabilized SA content is 83 wt% in the SA/CNS composites. • Increasing thermal conductivity of composite phase change material with high amount of latent heat. - Abstract: Stearic acid (SA) is one of the main phase change materials (PCMs) for medium temperature thermal energy storage systems. In order to stabilize the shape and enhance the thermal conductivity of SA, the effects of adding carbon nanospheres (CNSs) as a carbon nanofiller were examined experimentally. The maximum mass fraction of SA retained in CNSs was found as 80 wt% without the leakage of SA in a melted state, even when it was heated over the melting point of SA. The dropping point test shows that there was clearly no liquid leakage through the phase change process at the operating temperature range of the composite PCMs. The thermal stability and thermal properties of composite PCMs were investigated with a thermogravimetric analyzer (TGA) and differential scanning calorimeter (DSC), respectively. The thermal conductivity of the SA/CNS composite was determined by the laser flash method. The thermal conductivity at 35 °C increased about 105% for the highest loading of CNS (50 wt%). The thermal cycling test proved that form-stable composite PCMs had good thermal reliability and chemical durability after 1000 cycles of melting and freezing, which is advantageous for latent heat thermal energy storage (LHTES)

  13. Analysis of thermal-dose response to heat

    International Nuclear Information System (INIS)

    Storm, F.; Roe, D.; Drury, B.

    1987-01-01

    The authors reasoned that if hyperthermia alone has a clinical anti-tumor effect, response should have a thermal dose relationship. The authors analyzed 100 patients with advanced cancer treated with magnetic-induction. Three methods of determining thermal dose were used: (A) t1x10, the lowest temperature sustained throughout the tumor for 30-60min during the first of ten daily treatments, which represents one usual course of ten hourly sessions; (B) t43 (equivalent minutes at 43C) which accounts for non-linear tumor heating by combining serially measured temperatures during the first treatment with a mathematical description of the time-temperature relationship for thermal inactivation or damage; (C) Ct43 (cumulative t43), which represents the t43 value multiplied by the actual number of subsequent daily treatments received. Response was defined as CR+PR+MR. The results show a statistically significant effect of heat alone for t1x10, t43, and Ct43. These analyses demonstrate a thermal-dose relationship between hyperthermia therapy and tumor response as a sole independent variable, which indicates that heat therapy has clinical anti-cancer activity

  14. THERMAL CHARACTERISTICS OF PHASE CHANGE MATERIAL USED AS THERMAL STORAGE SYSTEM BY USING SOLAR ENERGY

    Directory of Open Access Journals (Sweden)

    Kadhim F. Nasir

    2018-01-01

    Full Text Available In this paper, the melting processes of phase change material in a shell and tube heat exchanger by using solar thermal energy have been investigated numerically and experimentally. All experimental were outdoor tested at AL-Mussaib city-Babylon-Iraq (Lat 32.5 º North, and long 44.3 º East with N-S collector direction at tilt angle of 32.5 º with the horizontal. The phase change material used in this work is black color Iraqi origin pure Paraffin with amount of 12 kg. In the experimental setup evacuted tube solar collector is employed for melting phase change material in shell regime. Different volume flow rates for the water flow inside the inner tube of heat exchanger namely (200, 300, and 500 LPH for Reynolds number namely (15000, 23000, 38000 respectively were used for each season from August 2016 to January 2017. The numerical investigation involves a three dimension numerical solution of model by a commercial package ANSYS FLUENT 15.0. The boundary conditions of the model that solved by the numerical solution have been taken from the experimental tests. The experimental results indicated that the inner tube inlet and ambient temperatures has a significant effects on the melting process compared with the volume flow rates. Studying phase change material temperature distribution, it is exposed that a melting temperature of the phase change material in summer season needed time of (3-4 hours only, while it needed more time; (14-16 hours in winter season. Increasing solar radiation and ambient temperature reduces the melting time of phase change material. Increasing water temperature difference of inner tube increased the heat gained for phase change material. The results obtained from numerical solution presented the static temperature contours and showed that the temperature distribution of phase change material give good validations with experimental results with percentage deviation of 2.7%. The present experimental results have been

  15. Combinatory Models for Predicting the Effective Thermal Conductivity of Frozen and Unfrozen Food Materials

    OpenAIRE

    K. S. Reddy; P Karthikeyan

    2010-01-01

    A model to predict the effective thermal conductivity of heterogeneous materials is proposed based on unit cell approach. The model is combined with four fundamental effective thermal conductivity models (Parallel, Series, Maxwell-Eucken-I, and Maxwell-Eucken-II) to evolve a unifying equation for the estimation of effective thermal conductivity of porous and nonporous food materials. The effect of volume fraction (ν) on the structure composition factor (ψ) of the food materials is studied. Th...

  16. Transient analysis of a thermal storage unit involving a phase change material

    Science.gov (United States)

    Griggs, E. I.; Pitts, D. R.; Humphries, W. R.

    1974-01-01

    The transient response of a single cell of a typical phase change material type thermal capacitor has been modeled using numerical conductive heat transfer techniques. The cell consists of a base plate, an insulated top, and two vertical walls (fins) forming a two-dimensional cavity filled with a phase change material. Both explicit and implicit numerical formulations are outlined. A mixed explicit-implicit scheme which treats the fin implicity while treating the phase change material explicitly is discussed. A band algorithmic scheme is used to reduce computer storage requirements for the implicit approach while retaining a relatively fine grid. All formulations are presented in dimensionless form thereby enabling application to geometrically similar problems. Typical parametric results are graphically presented for the case of melting with constant heat input to the base of the cell.

  17. Study of materials used for the thermal protection of the intake system for internal combustion engines

    Science.gov (United States)

    Birtok-Băneasă, C.; Raţiu, S.; Puţan, V.; Josan, A.

    2018-01-01

    The present paper focuses on calculation of thermal conductivity for a new materials developed by the authors, using the heat flux plate method. This experimental method consists in placing the sample of the new material in a calorimetric chamber and heating from underside. As the heat flux which passes through the sample material is constant and knowing the values of the temperatures for the both sides of sample, the sample material thermal conductivity is determined. Six types of different materials were tested. Based on the experimental data, the values of the thermal conductivity according to the material and the average temperature were calculated and plotted.

  18. Advanced Thermal Protection Systems (ATPS), Aerospace Grade Carbon Bonded Carbon Fiber Material, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — Carbon bonded carbon fiber (CBCF) insulating material is the basis for several highly successful NASA developed thermal protection systems (TPS). Included among...

  19. Holographic thermal DC response in the hydrodynamic limit

    Science.gov (United States)

    Banks, Elliot; Donos, Aristomenis; Gauntlett, Jerome P.; Griffin, Tom; Melgar, Luis

    2017-02-01

    We consider black hole solutions of Einstein gravity that describe deformations of CFTs at finite temperature in which spatial translations have been broken explicitly. We focus on deformations that are periodic in the non-compact spatial directions, which effectively corresponds to considering the CFT on a spatial torus with a non-trivial metric. We apply a DC thermal gradient and show that in a hydrodynamic limit the linearised, local thermal currents can be determined by solving linearised, forced Navier-Stokes equations for an incompressible fluid on the torus. We also show how sub-leading corrections to the thermal current can be calculated as well as showing how the full stress tensor response that is generated by the DC source can be obtained. We also compare our results with the fluid-gravity approach.

  20. Elastomeric thermal interface materials with high through-plane thermal conductivity from carbon fiber fillers vertically aligned by electrostatic flocking.

    Science.gov (United States)

    Uetani, Kojiro; Ata, Seisuke; Tomonoh, Shigeki; Yamada, Takeo; Yumura, Motoo; Hata, Kenji

    2014-09-03

    Electrostatic flocking is applied to create an array of aligned carbon fibers from which an elastomeric thermal interface material (TIM) can be fabricated with a high through-plane thermal conductivity of 23.3 W/mK. A high thermal conductivity can be achieved with a significantly low filler level (13.2 wt%). As a result, this material retains the intrinsic properties of the matrix, i.e., elastomeric behavior. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Liquid Whey Protein Concentrates Produced by Ultrafiltration as Primary Raw Materials for Thermal Dairy Gels

    Directory of Open Access Journals (Sweden)

    Marta Henriques

    2017-01-01

    Full Text Available The aim of this work is to study the gelation properties of liquid whey protein concentrates (LWPC produced by ultrafiltration (UF as raw material for thermally induced gels intended for food applications. LWPC thermal gelation was performed using different types of LWPC (non-defatted, defatted and diafiltered of different protein mass fractions and pH. Most of the produced gels showed viscoelastic behaviour. Non-defatted LWPC gave stronger heat-induced gels with a more cohesive microstructure, a higher water holding capacity and also higher elastic modulus (G’ and viscous modulus (G’’. Gel properties were not improved in products with lower content of non-protein compounds. As expected, the increase in protein mass fraction positively influences protein interactions. However, the pH is responsible for the equilibrium between attraction and repulsion forces in the gel components that influence gel hardness and water holding capacity.

  2. Thermal desorption spectroscopy for investigating hydrogen isotope behavior in materials

    International Nuclear Information System (INIS)

    Xia Tirui; Yang Hongguang; Zhan Qin; Han Zhibo; He Changshui

    2012-01-01

    The behavior of hydrogen isotope generated in fusion reactor materials is the key issue for safety and economic operation of fusion reactors and becomes an interesting field. In order to investigate the mechanism of hydrogen isotope such as diffusion, release and retention, a high-sensitivity thermal desorption spectroscopy (TDS) in combination with a quadruple mass spectrometer (QMS) was developed. A major technical breakthrough in ultrahigh vacuum (UHV), low hydrogen background, linear heating and sensitivity calibration of TDS system was made. UHV of l × 10 -7 Pa and low hydrogen background of l × 10 -9 Pa were obtained by combining turbo molecule pump and sputter ion pump. Specimens can be linearly heated up to 1173 K at the rate of 1 to 50 K/min under the MCGS PID software. Sensitivity calibration of the TDS system was accomplished using a special deuterium leak in the detector mode of QMS second electron multiplier. The desorption sensitivity coefficient and the minimum detection limit of deuterium desorption rate are 6.22 × l0 24 s -l · and l.24 × l0 -10 s -1 , respectively. The measurement was also routinely conducted on a specimen of standard, deuterium-containing Zr-4 alloy maintained in the laboratory, so as to validate the TDS method. (authors)

  3. Evaluation of thermal shock strengths for graphite materials using a laser irradiation method

    International Nuclear Information System (INIS)

    Kim, Jae Hoon; Lee, Young Shin; Kim, Duck Hoi; Park, No Seok; Suh, Jeong; Kim, Jeng O.; Il Moon, Soon

    2004-01-01

    Thermal shock is a physical phenomenon that occurs during the exposure to rapidly high temperature and pressure changes or during quenching of a material. The rocket nozzle throat is exposed to combustion gas of high temperature. Therefore, it is important to select suitable materials having the appropriate thermal shock resistance and to evaluate these materials for rocket nozzle design. The material of this study is ATJ graphite, which is the candidate material for rocket nozzle throat. This study presents an experimental method to evaluate the thermal shock resistance and thermal shock fracture toughness of ATJ graphite using laser irradiation. In particular, thermal shock resistance tests are conducted with changes of specimen thickness, with laser source irradiated at the center of the specimen. Temperature distributions on the specimen surface are detected using type K and C thermocouples. Scanning electron microscope (SEM) is used to observe the thermal cracks on specimen surface

  4. Current situation and development tendency of thermal spraying materials in China

    Institute of Scientific and Technical Information of China (English)

    YU; Yue-guang

    2005-01-01

    The current situations of thermal spraying materials in China are described in this paper.The thermal spraying technology in China has a great progress over tens of years. More than one hundred varieties of material products serve thermal spraying producing now. They belong to three kinds, powders,wires and rods. Technologies for producing alloy, ceramic and composite powders, alloy and cored wires,and oxide ceramic rods are applied to large-scale production. Many research and development works on advanced materials for thermal spraying are carrying out recent years. They show that the general tendencies of thermal spraying materials in China are composite or low-impurity component, ultrafine or nanosized microstructure, high properties, and specialized and systematized applications. Thermal spraying materials have great prospects with the development of saving society in China.

  5. Effects of Brass (Cu3Zn2) as High Thermal Expansion Material on Shrink Disc Performance During High Thermal Loading

    Science.gov (United States)

    Mazlan, MIS; Mohd, SA; Bahar, ND; Aziz, SAA

    2018-03-01

    This research work is focused on shrink disc operation at high temperature. Geometrical and material design selections have been done by taking into consideration the existing shrink disc operating at high temperature condition. The existing shrink disc confronted slip between shaft and shaft sleeve during thermal loading condition. The assessment has been obtained through virtual experiment by using Finite Element Analysis (FEA) -Thermal Transient Stress for 900 seconds with 300 °C of thermal loading. This investigation consists of the current and improved version of shrink disc, where identical geometries and material properties were utilized. High Thermal Expansion (HTE) material has been introduced to overcome the current design of the shrink disc. Brass (Cu3Zn2) has been selected as the HTE material in the improved shrink disc design due to its high thermal expansion properties. The HTE has shown a significant improvement on the total contact area and contact pressure on the shaft and the shaft sleeve. The improved shrink disc embedded with HTE during thermal loading exhibit a minimum of 1244.1 mm2 of the total area on shaft and shaft sleeve which uninfluenced the total contact area at normal condition which is 1254.3 mm2. Meanwhile, the total pressure of improved shrink disc had an increment of 108.1 MPa while existing shrink disc total pressure has lost 17.2 MPa during thermal loading.

  6. Packaging material and flexible medical tubing containing thermally exfoliated graphite oxide

    Science.gov (United States)

    Prud'homme, Robert K. (Inventor); Aksay, Ilhan A. (Inventor)

    2011-01-01

    A packaging material or flexible medical tubing containing a modified graphite oxide material, which is a thermally exfoliated graphite oxide with a surface area of from about 300 m.sup.2/g to 2600 m.sup.2/g.

  7. Thermal shock resistances of a bonding material of C/C composite and copper

    International Nuclear Information System (INIS)

    Kurumada, Akira; Oku, Tatsuo; Kawamata, Kiyohiro; Motojima, Osamu; Noda, Nobuaki; McEnaney, B.

    1997-01-01

    The purpose of this study is to contribute to the development and the safety design of plasma facing components for fusion reactor devices. We evaluated the thermal shock resistance and the thermal shock fracture toughness of a bonding material which was jointed a carbon-fiber-reinforced carbon composite (C/C composite) to oxygen-free copper. We also examined the microstructures of the bonding layers using a scanning electron microscope before and after thermal shock tests. The bonding material did not fracture during thermal shock tests. However, thermal cracks and delamination cracks were observed in the bonding layers. (author)

  8. Study of Material Compatibility for a Thermal Energy Storage System with Phase Change Material

    Directory of Open Access Journals (Sweden)

    Songgang Qiu

    2018-03-01

    Full Text Available The suitability of stainless steel 316L and Inconel 625 for use in a latent heat thermal energy storage (TES system was investigated. A NaCl–NaF eutectic mixture with a melting temperature of 680 °C was used as the phase change material (PCM. Containers were filled with the PCM prior to heating to 750 °C, then examined after 100 and 2500 h of high-temperature exposure by analyzing the material surface and cross-section areas. A small amount of corrosion was present in both samples after 100 h. Neither sample suffered significant damage after 2500 h. The undesirable inter-granular grain boundary attack found in SS316L samples was in the order of 1–2 µm in depth. On Inconel 625 sample surface, an oxide complex formed, resisting material dissolution into the PCM. The surface morphology of tested samples remained largely unchanged after 2500 h, but the corrosion pattern changed from an initially localized corrosion penetration to a more uniform type. After 2500 h, the corrosion depth of Inconel 625 remained at roughly 1–2 µm, indicating that the corrosion rate decelerated. Both materials demonstrated good compatibility with the chosen NaF–NaCl eutectic salt, but the low corrosion activity in Inconel 625 samples shows a performance advantage for long term operation.

  9. Preparation, characterization, and thermal properties of starch microencapsulated fatty acids as phase change materials thermal energy storage applications

    Science.gov (United States)

    Stable starch-oil composites can be prepared from renewable resources by excess steam jet-cooking aqueous slurries of starch and vegetable oils or other hydrophobic materials. Fatty acids such as stearic acid are promising phase change materials (PCMs) for latent heat thermal energy storage applica...

  10. Thermal Performance and Reliability Characterization of Bonded Interface Materials (BIMs): Preprint

    Energy Technology Data Exchange (ETDEWEB)

    DeVoto, D.; Paret, P.; Mihalic, M.; Narumanchi, S.; Bar-Cohen, A.; Matin, K.

    2014-08-01

    Thermal interface materials are an important enabler for low thermal resistance and reliable electronics packaging for a wide array of applications. There is a trend towards bonded interface materials (BIMs) because of their potential for low thermal resistivity (< 1 mm2K/W). However, BIMs induce thermomechanical stresses in the package and can be prone to failures and integrity risks. Deteriorated interfaces can result in high thermal resistance in the package and degradation and/or failure of the electronics. DARPA's Thermal Management Technologies program has addressed this challenge, supporting the development of mechanically-compliant, low resistivity nano-thermal interface (NTI) materials. In this work, we describe the testing procedure and report the results of NREL's thermal performance and reliability characterization of an initial sample of four different NTI-BIMs.

  11. Research on technology of evaluating thermal property data of nuclear power materials

    International Nuclear Information System (INIS)

    Imai, Hidetaka; Baba, Tetsuya; Matsumoto, Tsuyoshi; Kishimoto, Isao; Taketoshi, Naoyuki; Arai, Teruo

    1997-01-01

    For the materials of first wall and diverter of nuclear fusion reactor, in order to withstand steady and unsteady high heat flux load, excellent thermal characteristics are required. It is strongly demanded to measure such thermal property values as heat conductivity, heat diffusivity, specific heat capacity, emissivity and so using small test pieces up to higher than 2000degC. As the materials of nuclear reactors are subjected to neutron irradiation, in order to secure the long term reliability of the materials, it is very important to establish the techniques for forecasting the change of the thermal property values due to irradiation effect. Also the establishment of the techniques for estimating the thermal property values of new materials like low radioactivation material is important. In National Research Laboratory of Metrology, the research on the advancement of the measuring technology for high temperature thermal properties has resulted in the considerably successful development of such technologies. In this research, the rapid measurement of thermal property values up to superhigh temperature with highest accuracy, the making of thermal property data set of high level, the analysis and evaluation of the correlation of material characters and thermal property values, and the development of the basic techniques for estimating the thermal property values of solid materials are aimed at and advanced. These are explained. (K.I.)

  12. Human thermal physiological and psychological responses under different heating environments.

    Science.gov (United States)

    Wang, Zhaojun; Ning, Haoran; Ji, Yuchen; Hou, Juan; He, Yanan

    2015-08-01

    Anecdotal evidence suggests that many residents of severely cold areas of China who use floor heating (FH) systems feel warmer but drier compared to those using radiant heating (RH) systems. However, this phenomenon has not been verified experimentally. In order to validate the empirical hypothesis, and research the differences of human physiological and psychological responses in these two asymmetrical heating environments, an experiment was designed to mimic FH and RH systems. The subjects participating in the experiment were volunteer college-students. During the experiment, the indoor air temperature, air speed, relative humidity, globe temperature, and inner surface temperatures were measured, and subjects' heart rate, blood pressure and skin temperatures were recorded. The subjects were required to fill in questionnaires about their thermal responses during testing. The results showed that the subjects' skin temperatures, heart rate and blood pressure were significantly affected by the type of heating environment. Ankle temperature had greatest impact on overall thermal comfort relative to other body parts, and a slightly cool FH condition was the most pleasurable environment for sedentary subjects. The overall thermal sensation, comfort and acceptability of FH were higher than that of RH. However, the subjects of FH felt drier than that of RH, although the relative humidity in FH environments was higher than that of the RH environment. In future environmental design, the thermal comfort of the ankles should be scrutinized, and a FH cool condition is recommended as the most comfortable thermal environment for office workers. Consequently, large amounts of heating energy could be saved in this area in the winter. The results of this study may lead to more efficient energy use for office or home heating systems. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Ablation, Thermal Response, and Chemistry Program for Analysis of Thermal Protection Systems

    Science.gov (United States)

    Milos, Frank S.; Chen, Yih-Kanq

    2010-01-01

    In previous work, the authors documented the Multicomponent Ablation Thermochemistry (MAT) and Fully Implicit Ablation and Thermal response (FIAT) programs. In this work, key features from MAT and FIAT were combined to create the new Fully Implicit Ablation, Thermal response, and Chemistry (FIATC) program. FIATC is fully compatible with FIAT (version 2.5) but has expanded capabilities to compute the multispecies surface chemistry and ablation rate as part of the surface energy balance. This new methodology eliminates B' tables, provides blown species fractions as a function of time, and enables calculations that would otherwise be impractical (e.g. 4+ dimensional tables) such as pyrolysis and ablation with kinetic rates or unequal diffusion coefficients. Equations and solution procedures are presented, then representative calculations of equilibrium and finite-rate ablation in flight and ground-test environments are discussed.

  14. Thermal characteristics of expanded perlite/paraffin composite phase change material with enhanced thermal conductivity using carbon nanotubes

    International Nuclear Information System (INIS)

    Karaipekli, Ali; Biçer, Alper; Sarı, Ahmet; Tyagi, Vineet Veer

    2017-01-01

    Highlights: • Expanded perlite/n-eicosane composite for thermal energy storage was prepared. • Addition of CNTs increases considerably the thermal conductivity of the composite. • The composite PCM including 1 wt% CNTs is promising material. - Abstract: Paraffins constitute a class of solid-liquid organic phase change materials (PCMs). However, low thermal conductivity limits their feasibility in thermal energy storage (TES) applications. Carbon nano tubes (CNTs) are one of the best materials to increase the thermal conductivity of paraffins. In this regard, the present study is focus on the preparation, characterization, and improvement of thermal conductivity using CNTs as well as determination of TES properties of expanded perlite (ExP)/n-eicosane (C20) composite as a novel type of form-stable composite PCM (F-SCPCM). It was found that the ExP could retain C20 at weight fraction of 60% without leakage. The SEM and FTIR analyses were carried out to characterize the microstructure and chemical properties of the composite PCM. The TES properties of the prepared F-SCPCM were determined using DSC and TG analyses. The analysis results showed that the components of the composite are in good compatibleness and C20 used as PCM are well-infiltrated into the structure of ExP/CNTs matrix. The DSC analysis indicated that the ExP/C20/CNTs (1 wt%) composite has a melting point of 36.12 °C and latent heat of 157.43 J/g. The TG analysis indicated that the F-SCPCM has better thermal durability compared with pure C20 and also it has good long term-TES reliability. In addition, the effects of CNTs on the thermal conductivity of the composite PCM were investigated. Compared to ExP/C20 composite, the use of CNTs has apparent improving effect for the thermal conductivity without considerably affecting the compatibility of components, TES properties, and thermal stability.

  15. A nano-graphite/paraffin phase change material with high thermal conductivity

    International Nuclear Information System (INIS)

    Li, Min

    2013-01-01

    Highlights: ► Paraffin and NG formed a nanoscale compound. ► The thermal conductivity increased gradually with the content of NG. ► The thermal conductivity of the material containing 10% NG were 0.9362 W/m K. - Abstract: Nano-graphite (NG)/paraffin composites were prepared as composite phase change materials. NG has the function of improving the thermal conductivity of the composite. The microstructure and thermal properties of the materials were examined with environmental scanning electron microscopy and differential scanning calorimetry. The results indicated that the NG layers were randomly dispersed in the paraffin, and the thermal conductivity increased gradually with the content of NG. Thermal conductivity of the material containing 10% NG were 0.9362 W/m K

  16. Influence of nanomaterials on properties of latent heat solar thermal energy storage materials – A review

    International Nuclear Information System (INIS)

    Raam Dheep, G.; Sreekumar, A.

    2014-01-01

    Highlights: • Classification of phase change materials. • Studies on phase change properties of various phase change materials. • Influence of nanomaterials on properties of phase change materials. - Abstract: Thermal energy storage system plays a critical role in developing an efficient solar energy device. As far as solar thermal devices are concerned, there is always a mismatch between supply and demand due to intermittent and unpredictable nature of solar radiation. A well designed thermal energy storage system is capable to alleviate this demerit by providing a constant energy delivery to the load. Many research works is being carried out to determine the suitability of thermal energy storage system to integrate with solar thermal gadgets. This review paper summarizes the numerous investigations on latent heat thermal energy storage using phase change materials (PCM) and its classification, properties, selection criteria, potential research areas and studies involved to analyze the thermal–physical properties of PCM

  17. A Study on thermal-hydraulic characteristics of the coolant materials for the transmutation reactor

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Chang Hyun; You, Young Woo; Cho, Jae Seon; Kim, Ju Youl; Kim, Do Hyoung; Kim, Yoon Ik; Yang, Hui Chang [Seoul National University, Taejon (Korea)

    1998-03-01

    The objective of this study is to provide the direction of transmutation reactor design in terms of thermal hydraulics especially through the analysis of thermal hydraulic characteristics of various candidate materials for the transmutation reactor coolant. In this study, the characteristics of coolant materials used in current nuclear power plants and candidate materials for transmutation reactor are analyzed and compared. To evaluate the thermal hydraulic characteristics, the preliminary thermal-hydraulic calculation is performed for the candidate coolant materials of transmutation reactor. An analysis of thermal-hydraulic characteristics of transmutation reactor. An analysis of thermal-hydraulic characteristics of Sodium, Lead, Lead-Bismuth, and Lead-Lithium among the liquid metals considered as the coolant of transmutation reactor is performed by using computational fluid dynamics code FLUENT, and SIMPLER algorithm. (author). 50 refs., 40 figs., 30 tabs.

  18. 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...

  19. Hygrothermal response of a dwelling house. Thermal comfort criteria

    Directory of Open Access Journals (Sweden)

    Adrian IACOB

    2015-12-01

    Full Text Available The use of local natural materials in order to reduce the environmental negative impact of buildings has become common practice in recent years; such buildings are to be found in all regions of the planet. The high level of thermal protection provided by the envelope elements made from natural materials such as straw bale insulation, hemp insulation or sheep wool, and their lack of thermal massiveness require a more complex analysis on their ability to keep interior comfort without accentuated variations. This paper proposes a comparative analysis between different solutions for a residential building located near a Romanian city, Cluj-Napoca. The elements of the building envelope are designed in three alternative solutions, using as substitute to classical solutions (concrete and polystyrene, masonry and polystyrene, straw bales and rammed earth for enclosing elements. For this purpose there are conducted numerical simulations of heat and mass transfer, using a mathematical model that allows the analysis of indoor comfort, by comparing both objective factors (air temperature, operative temperature and relative humidity and subjective factors, which are needed to define interior thermal comfort indices PPD and PMV. Finally, a set of conclusions are presented and future research directions are drawn.

  20. High temperature viscoplastic ratchetting: Material response or modeling artifact

    International Nuclear Information System (INIS)

    Freed, A.D.

    1991-01-01

    Ratchetting, the net accumulation of strain over a loading cycle, is a deformation mechanism that leads to distortions in shape, often resulting in a loss of function that culminates in structural failure. Viscoplastic ratchetting is prevalent at high homologous temperatures where viscous characteristics are prominent in material response. This deformation mechanism is accentuated by the presence of a mean stress; a consequence of interaction between thermal gradients and structural constraints. Favorable conditions for viscoplastic ratchetting exist in the Stirling engines being developed by the National Aeronautics and Space Administration (NASA) and the Department of Energy (DOE) for space and terrestrial power applications. To assess the potential for ratchetting and its effect on durability of high temperature structures requires a viscoplastic analysis of the design. But ratchetting is a very difficult phenomenon to accurately model. One must therefore ask whether the results from such an analysis are indicative of actual material behavior, or if they are artifacts of the theory being used in the analysis. There are several subtle aspects in a viscoplastic model that must be dealt with in order to accurately model ratchetting behavior, and therefore obtain meaningful predictions from it. In this paper, some of these subtlties and the necessary ratchet experiments needed to obtain an accurate viscoplastic representation of a material are discussed

  1. In-situ measurements of material thermal parameters for accurate LED lamp thermal modelling

    NARCIS (Netherlands)

    Vellvehi, M.; Perpina, X.; Jorda, X.; Werkhoven, R.J.; Kunen, J.M.G.; Jakovenko, J.; Bancken, P.; Bolt, P.J.

    2013-01-01

    This work deals with the extraction of key thermal parameters for accurate thermal modelling of LED lamps: air exchange coefficient around the lamp, emissivity and thermal conductivity of all lamp parts. As a case study, an 8W retrofit lamp is presented. To assess simulation results, temperature is

  2. Investigations on the effect of creep stress on the thermal properties of metallic materials

    International Nuclear Information System (INIS)

    Radtke, U.; Crostack, H.A.; Winschuh, E.

    1995-01-01

    Using thermal wave analysis with front side infrared detection on sample material damaged by creep, one examines whether the creep stress has an effect on the thermal material properties and to what effect this can be used to estimate the remaining service life. (orig.) [de

  3. Thermal modelling of normal distributed nanoparticles through thickness in an inorganic material matrix

    Science.gov (United States)

    Latré, S.; Desplentere, F.; De Pooter, S.; Seveno, D.

    2017-10-01

    Nanoscale materials showing superior thermal properties have raised the interest of the building industry. By adding these materials to conventional construction materials, it is possible to decrease the total thermal conductivity by almost one order of magnitude. This conductivity is mainly influenced by the dispersion quality within the matrix material. At the industrial scale, the main challenge is to control this dispersion to reduce or even eliminate thermal bridges. This allows to reach an industrially relevant process to balance out the high material cost and their superior thermal insulation properties. Therefore, a methodology is required to measure and describe these nanoscale distributions within the inorganic matrix material. These distributions are either random or normally distributed through thickness within the matrix material. We show that the influence of these distributions is meaningful and modifies the thermal conductivity of the building material. Hence, this strategy will generate a thermal model allowing to predict the thermal behavior of the nanoscale particles and their distributions. This thermal model will be validated by the hot wire technique. For the moment, a good correlation is found between the numerical results and experimental data for a randomly distributed form of nanoparticles in all directions.

  4. Neutralization of Aerosolized Bio-Agents by Filled Nanocomposite Materials through Thermal and Chemical Inactivation Mechanisms

    Science.gov (United States)

    2016-06-01

    Bio -agents by Filled Nanocomposite Materials through Thermal and Chemical Inactivation Mechanisms Distribution Statement A. Approved for public...of Cincinnati Project Title: Neutralization of Aerosolized Bio -agents by Filled Nanocomposite Materials through Thermal and Chemical Inactivation...fire ball, where they will not effectively interact with any viable bio -aerosol. 1.1.4. Conclusions Cryo-milling is necessary to achieve a

  5. Investigation of Thermal Expansion of a Glass Ceramic Material with an Extra-Low Thermal Linear Expansion Coefficient

    Science.gov (United States)

    Kompan, T. A.; Korenev, A. S.; Lukin, A. Ya.

    2008-10-01

    The artificial material sitall CO-115M was developed purposely as a material with an extra-low thermal expansion. The controlled crystallization of an aluminosilicate glass melt leads to the formation of a mixture of β-spodumen, β-eucryptite, and β-silica anisotropic microcrystals in a matrix of residual glass. Due to the small size of the microcrystals, the material is homogeneous and transparent. Specific lattice anharmonism of these microcrystal materials results in close to zero average thermal linear expansion coefficient (TLEC) of the sitall material. The thermal expansion coefficient of this material was measured using an interferometric method in line with the classical approach of Fizeau. To obtain the highest accuracy, the registration of light intensity of the total interference field was used. Then, the parameters of the interference pattern were calculated. Due to the large amount of information in the interference pattern, the error of the calculated fringe position was less than the size of a pixel of the optical registration system. The thermal expansion coefficient of the sitall CO-115M and its temperature dependence were measured. The TLEC value of about 3 × 10-8 K-1 to 5 × 10-8 K-1 in the temperature interval from -20 °C to +60 °C was obtained. A special investigation was carried out to show the homogeneity of the material.

  6. Thermal conductivity and latent heat thermal energy storage properties of LDPE/wax as a shape-stabilized composite phase change material

    International Nuclear Information System (INIS)

    Trigui, Abdelwaheb; Karkri, Mustapha; Krupa, Igor

    2014-01-01

    Highlights: • This study deals with the comparison of experimental results for different PCM composite to be used in passive solar walls. • This paper reports on the successful use of a specific experimental method in order to characterize the phase change effects. • The results have shown that most important thermal properties of these composites at the solid and liquid states. • Results indicate the thermal effectiveness of phase change material and significant amount of energy saving can be achieved. • Heat flux measurements are a very interesting experimental source of data which comes to complete the calorimetric device (DSC). - Abstract: Phase change material (PCM) composites based on low-density polyethylene (LDPE) with paraffin waxes were investigated in this study. The composites were prepared using a meltmixing method with a Brabender-Plastograph. The LDPE as the supporting matrix kept the molten waxes in compact shape during its phase transition from solid to liquid. Immiscibility of the PCMs (waxes) and the supporting matrix (LDPE) is a necessary property for effective energy storage. Therefore, this type paraffin can be used in a latent heat storage system without encapsulation. The objective of this research is to use PCM composite as integrated components in a passive solar wall. The proposed composite TROMBE wall allows daily storage of the solar energy in a building envelope and restitution in the evening, with a possible control of the air flux in a ventilated air layer. An experimental set-up was built to determine the thermal response of these composites to thermal solicitations. In addition, a DSC analysis was carried out. The results have shown that most important thermal properties of these composites at the solid and liquid states, like the “apparent” thermal conductivity, the heat storage capacity and the latent heat of fusion. Results indicate the performance of the proposed system is affected by the thermal effectiveness of

  7. Numerical investigation into thermal load responses of steel railway bridge

    Science.gov (United States)

    Saravana Raja Mohan, K.; Sreemathy, J. R.; Saravanan, U.

    2017-07-01

    Bridge design requires consideration of the effects produced by temperature variations and the resultant thermal gradients in the structure. Temperature fluctuation leads to expansion and contraction of bridges and these movements are taken care by providing expansion joints and bearings. Free movements of a member can be restrained by imposing certain boundary condition but at the same time considerable allowances should be made for the stresses resulting from this restrained condition since the additional deformations and stresses produced may affect the ultimate and serviceability limit states of the structure. If the reaction force generated by the restraints is very large, then its omission can lead to unsafe design. The principal objective of this research is to study the effects of temperature variation on stresses and deflection in a steel railway bridge. A numerical model, based on finite element analysis is presented for evaluating the thermal performance of the bridge. The selected bridge is analyzed and the temperature field distribution and the corresponding thermal stresses and strains are calculated using the finite element software ABAQUS. A thorough understanding of the thermal load responses of a structure will result in safer and dependable design practices.

  8. Thermal characteristics of manganese (II) nitrate hexahydrate as a phase change material for cooling systems

    International Nuclear Information System (INIS)

    Nagano, K.; Mochida, T.; Takeda, S.; Domanski, R.; Rebow, M.

    2003-01-01

    The imbalance of electrical demand in summer due to cooling system demand is a big problem in many countries. One promising solution is shifting peak demand from early afternoon to night by utilizing natural cold energy resources such as cool outside air during night or running a refrigerator driven by midnight power. In these cases, using the thermal energy storage (TES) of phase change material (PCM) which has a melting point from 15 to 25 deg. C is one of the most effective ideas. However, few suitable PCMs for this temperature range are at present commercially available. This study aims to evaluate the potential of Mn(NO 3 ) 2 · 6H 2 O (manganese (II) nitrate hexahydrate) as a new PCM for the TES of cooling systems. First, experiments on the modulation of the melting point of Mn(NO 3 ) 2 · 6H 2 O and reduction of supercooling were made by dissolving small amounts of salts in the material. Consequently, MnCl 2 · 4H 2 O was found to have good performance with regard to both modulation of the melting temperature and the heat of fusion. Next, a thermal response test was carried out by using a small cylindrical vessel. Results showed that the required temperature levels for charging and discharging the heat of this mixture were clarified. In addition, the price and safety of this material as a PCM are discussed

  9. 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

  10. Palmitic acid/polypyrrole composites as form-stable phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Silakhori, Mahyar; Metselaar, Hendrik Simon Cornelis; Mahlia, Teuku Meurah Indra; Fauzi, Hadi; Baradaran, Saeid; Naghavi, Mohammad Sajad

    2014-01-01

    Highlights: • A novel phase change composite of palmitic acid–polypyrrole(PA–PPy) was fabricated. • Thermal properties of PA–PPy are characterized in different mass ratios of PA–PPy. • Thermal cycling test showed that form stable PCM had a favorable thermal reliability. - Abstract: In this study a novel palmitic acid (PA)/polypyrrole (PPy) form-stable PCMs were readily prepared by in situ polymerization method. PA was used as thermal energy storage material and PPy was operated as supporting material. Form-stable PCMs were investigated by SEM (scanning electron microscopy) and FTIR (Fourier transform infrared spectrometer) analysis that illustrated PA Particles were wrapped by PPy particles. XRD (X-ray diffractometer) was used for crystalline phase of PA/PPy composites. Thermogravimetry analysis (TGA) and differential scanning calorimetry (DSC) were used for investigating Thermal stability and thermal energy storage properties of prepared form-stable PCMs. According to the obtained results the form stable PCMs exhibited favorable thermal stability in terms of their phase change temperature. The form-stable PCMs (79.9 wt% loading of PA) were considered as the highest loading PCM with desirable latent heat storage of 166.3 J/g and good thermal stability. Accelerated thermal cycling tests also showed that form stable PCM had an acceptable thermal reliability. As a consequence of acceptable thermal properties, thermal stability and chemical stability, we can consider the new kind of form stable PCMs for low temperature solar thermal energy storage applications

  11. Gene Expression Dynamics Accompanying the Sponge Thermal Stress Response.

    Science.gov (United States)

    Guzman, Christine; Conaco, Cecilia

    2016-01-01

    Marine sponges are important members of coral reef ecosystems. Thus, their responses to changes in ocean chemistry and environmental conditions, particularly to higher seawater temperatures, will have potential impacts on the future of these reefs. To better understand the sponge thermal stress response, we investigated gene expression dynamics in the shallow water sponge, Haliclona tubifera (order Haplosclerida, class Demospongiae), subjected to elevated temperature. Using high-throughput transcriptome sequencing, we show that these conditions result in the activation of various processes that interact to maintain cellular homeostasis. Short-term thermal stress resulted in the induction of heat shock proteins, antioxidants, and genes involved in signal transduction and innate immunity pathways. Prolonged exposure to thermal stress affected the expression of genes involved in cellular damage repair, apoptosis, signaling and transcription. Interestingly, exposure to sublethal temperatures may improve the ability of the sponge to mitigate cellular damage under more extreme stress conditions. These insights into the potential mechanisms of adaptation and resilience of sponges contribute to a better understanding of sponge conservation status and the prediction of ecosystem trajectories under future climate conditions.

  12. Innovative improvements of thermal response tests - Final report

    Energy Technology Data Exchange (ETDEWEB)

    Poppei, J.; Schwarz, R. [AF-Colenco Ltd, Baden (Switzerland); Peron, H.; Silvani, C; Steinmann, G.; Laloui, L. [Swiss Federal Institute of Technology, Laboratoire de Mecanique des Sols, Lausanne (Switzerland); Wagner, R.; Lochbuehler, T.; Rohner, E. [Geowatt AG, Zuerich (Switzerland)

    2008-12-15

    This illustrated final report for Swiss Federal Office of Energy (SFOE) takes a look at innovative improvements to thermal response tests that are used to investigate the thermo-physical properties of the ground for the purpose of dimensioning borehole heat exchangers. Recent technical developments in the borehole investigation tools area provide a promising prerequisite for improved estimates of thermal conductivity. A mini-module developed at the Swiss Federal Institute of Technology EPFL which is suitable for fast and flexible thermal response testing is discussed as is a wireless miniature data logger for continuous temperature recordings in borehole heat exchangers up to a depth of 350 m. This allows high-resolution vertical temperature profiling in boreholes. International state-of-the-art methods are reviewed. The adaptations to the analytical methods necessary for the effective application of these tools are discussed and numerical methods available are looked at. The testing of the methods developed and their results are discussed, as is the influence of ground-water flow.

  13. Switchable and responsive surfaces and materials for biomedical applications

    CERN Document Server

    Zhang, Johnathan

    2015-01-01

    Surface modification of biomaterials can ultimately determine whether a material is accepted or rejected from the human body, and a responsive surface can further make the material ""smart"" and ""intelligent"". Switchable and Responsive Surfaces and Materials for Biomedical Applications outlines synthetic and biological materials that are responsive under different stimuli, their surface design and modification techniques, and applicability in regenerative medicine/tissue engineering,  drug delivery, medical devices, and biomedical diagnostics. Part one provides a detailed overview of swit

  14. Thermal memory influence on the thermoconducting component of indirect photoacoustic response

    International Nuclear Information System (INIS)

    Nešić, M; Popović, M; Gusavac, P; Šoškić, Z; Galović, S

    2012-01-01

    In this paper, a model of the thermoconducting component of the indirect photoacoustic (PA) response is derived that includes thermal memory properties of the examined material and its fluid environment. A comparison is made between the derived model and the classic one, which neglects the influence of thermal memory. It has been shown that, at modulation frequencies lower than a certain boundary frequency of the light source, these models tend to overlap, while at higher frequencies, noticeable differences occur. The boundary frequency depends on heat propagation velocity through the sample and its thickness. This observation limits the validity domain of previous models to a range lower than the boundary frequency, offering, at the same time, the possibility of obtaining thermal memory properties using PA effects at frequencies above it.

  15. The influence of core material on transient thermal impedances in transformers

    International Nuclear Information System (INIS)

    Górecki, K; Górski, K

    2016-01-01

    In the paper the results of measurements of thermal parameters of impulse-transformers containing cores made of different ferromagnetic materials are presented. Investigations were performed with the use of methods worked out in Gdynia Maritime University. The obtained results of measurements prove that the material of the core does not influence transient thermal impedance of the winding, whereas this parameter visibly changes with the change of spatial orientation of the transformer. In turn, the material of the core decides about transient thermal impedance of the core. Additionally, the influence of the core material on temperature distribution on the surface of the transformer was analysed. (paper)

  16. Linear analysis using secants for materials with temperature dependent nonlinear elastic modulus and thermal expansion properties

    Science.gov (United States)

    Pepi, John W.

    2017-08-01

    Thermally induced stress is readily calculated for linear elastic material properties using Hooke's law in which, for situations where expansion is constrained, stress is proportional to the product of the material elastic modulus and its thermal strain. When material behavior is nonlinear, one needs to make use of nonlinear theory. However, we can avoid that complexity in some situations. For situations in which both elastic modulus and coefficient of thermal expansion vary with temperature, solutions can be formulated using secant properties. A theoretical approach is thus presented to calculate stresses for nonlinear, neo-Hookean, materials. This is important for high acuity optical systems undergoing large temperature extremes.

  17. Extremal Overall Elastic Response of Polycrystalline Materials

    DEFF Research Database (Denmark)

    Bendsøe, Martin P; Lipton, Robert

    1997-01-01

    Polycrystalline materials comprised of grains obtained from a single anisotropic material are considered in the framework of linear elasticity. No assumptions on the symmetry of the polycrystal are made. We subject the material to independent external strain and stress fields with prescribed mean...

  18. Application of phase change materials in thermal management of electronics

    International Nuclear Information System (INIS)

    Kandasamy, Ravi; Wang Xiangqi; Mujumdar, Arun S.

    2007-01-01

    Application of a novel PCM package for thermal management of portable electronic devices was investigated experimentally for effects of various parameters e.g. power input, orientation of package, and various melting/freezing times under cyclic steady conditions. Also, a two-dimensional numerical study was made and compared the experimental results. Results show that increased power inputs increase the melting rate, while orientation of the package to gravity has negligible effect on the thermal performance of the PCM package. The thermal resistance of the device and the power level applied to the PCM package are of critical importance for design of a passive thermal control system. Comparison with numerical results confirms that PCM-based design is an excellent candidate design for transient electronic cooling applications

  19. Thermal Protection System Materials (TPSM): 3D MAT

    Data.gov (United States)

    National Aeronautics and Space Administration — The 3D MAT Project seeks to design and develop a game changing Woven Thermal Protection System (TPS) technology tailored to meet the needs of the Orion Multi-Purpose...

  20. Heat transfer and thermal storage performance of an open thermosyphon type thermal storage unit with tubular phase change material canisters

    International Nuclear Information System (INIS)

    Wang, Ping-Yang; Hu, Bo-Wen; Liu, Zhen-Hua

    2015-01-01

    Highlights: • A novel open heat pipe thermal storage unit is design to improve its performance. • Mechanism of its operation is phase-change heat transfer. • Tubular canisters with phase change material were placed in thermal storage unit. • Experiment and analysis are carried out to investigate its operation properties. - Abstract: A novel open thermosyphon-type thermal storage unit is presented to improve design and performance of heat pipe type thermal storage unit. In the present study, tubular canisters filled with a solid–liquid phase change material are vertically placed in the middle of the thermal storage unit. The phase change material melts at 100 °C. Water is presented as the phase-change heat transfer medium of the thermal storage unit. The tubular canister is wrapped tightly with a layer of stainless steel mesh to increase the surface wettability. The heat transfer mechanism of charging/discharging is similar to that of the thermosyphon. Heat transfer between the heat resource or cold resource and the phase change material in this device occurs in the form of a cyclic phase change of the heat-transfer medium, which occurs on the surface of the copper tubes and has an extremely high heat-transfer coefficient. A series of experiments and theoretical analyses are carried out to investigate the properties of the thermal storage unit, including power distribution, start-up performance, and temperature difference between the phase change material and the surrounding vapor. The results show that the whole system has excellent heat-storage/heat-release performance

  1. Thermal emitter comprising near-zero permittivity materials

    Science.gov (United States)

    Luk, Ting S.; Campione, Salvatore; Sinclair, Michael B.

    2017-10-25

    A novel thermal source comprising a semiconductor hyperbolic metamaterial provides control of the emission spectrum and the angular emission pattern. These properties arise because of epsilon-near-zero conditions in the semiconductor hyperbolic metamaterial. In particular, the thermal emission is dominated by the epsilon-near-zero effect in the doped quantum wells composing the semiconductor hyperbolic metamaterial. Furthermore, different properties are observed for s and p polarizations, following the characteristics of the strong anisotropy of hyperbolic metamaterials.

  2. Thermal studies on some new inorganic exchange materials

    International Nuclear Information System (INIS)

    Murthy, G.S.; Satyanarayana, J.; Reddy, V.N.

    1998-01-01

    The new inorganic exchangers developed in this laboratory zirconium phosphate-ammonium molybdophosphate (ZrP-AMP), titanium phosphate-ammonium molybdophosphate (TiP-AMP) and alumina-ammonium molybdophosphate (alumina-AMP) have been investigated extensively to study the removal of Cs from high level nuclear waste. As a part of these studies thermal studies on these substances have been carried out to elucidate the information on thermal stability of these exchangers. Results obtained are presented here and discussed. (author)

  3. Functional, Responsive Materials Assembled from Recombinant Oleosin

    Science.gov (United States)

    Hammer, Daniel

    Biological cells are surrounded by a plasma membrane made primarily of phospholipids that form a bilayer. This membrane is permselective and compartmentalizes the cell. A simple form of artificial cell is the vesicle, in which a phospholipid bilayer membrane surrounds an aqueous solution. However, there is no a priori reason why a membrane needs to be made of phospholipids. It could be made of any surfactant that forms a bilayer. We have assembled membranes and other structures from the recombinant plant protein oleosin. The ability to assemble from a recombinant protein means that every molecule is identical, we have complete control over the sequence, and hence can build in designer functionality with high fidelity, including adhesion and enzymatic activity. Such incorporation is trivial using the tools of molecular biology. We find that while many variants of oleosin make membranes, others make micelles and sheets. We show how the type of supramolecular structure can be altered by the conditions of solvent, such as ionic strength, and the architecture of the surfactant itself. We show that protease cleavable domains can be incorporated within oleosin, and be engineered to protect other functional domains such as adhesive motifs, to make responsive materials whose activity and shape depend on the action of proteases. We will also present the idea of making ``Franken''-oleosins, where large domains of native oleosin are replaced with domains from other functional proteins, to make hybrids conferred by the donor protein. Thus, we can view oleosin as a template upon which a vast array of designer functionalities can be imparted..

  4. Phase-change material as a thermal storage media

    Energy Technology Data Exchange (ETDEWEB)

    El Chazly, Nihad M; Khattab, Nagwa M [Dokki, Cairo (Egypt)

    2000-07-01

    Heat storage based on the sensible heating of media such as water, rock and earth represent the first generation of solar energy storage subsystems and technology for their utilization. However, recently the heat storage based on the latent heat associated with a change in phase of a material offers many advantages over sensible heat storage. The most important characteristic of such a subsystem is its a sufficient storage capacity. An idealized model visualizing a thermal capacitor using a phase change material is constructed and subjected to simulated solar system environmental conditions. The proposed model is of a flat plate geometry consisting of two panels compartments forming the body of the capacitor containing the paraffin, leaving at their inner surfaces a thin passage allowing the water flow. The whole structure was assumed to be insulated to minimize heat loss. An analysis of the model is conducted using Goodman technique to generate data about the temperature distribution, the melt thickness, and the heat stored in the PCM under conditions of: ( i ) constant mass flow rate tests for various water inlet temperatures and ( ii ) constant water inlet temperature for various mass flow rate. A FORTRAN computer program was constructed to perform the analysis. It was found the water outlet temperature increases with time until it becomes nearly equals to the inlet temperature. Increasing the mass flow rate for a given inlet temperature, decreases the time required for outlet temperature to reach a given value. Increasing inlet temperature for a given mass flow rate gives a very rapid decrease in the time required for the outlet water temperature to reach a given value. Instantaneous rate of heat storage was determined from the inlet-to- exit temperature differential and measured flow rate. This rate was then integrated numerically to determine the cumulative total energy stored as a function of time. It was found that the instantaneous rate of heat storage

  5. Micro/nano composited tungsten material and its high thermal loading behavior

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jinglian, E-mail: fjl@csu.edu.cn; Han, Yong; Li, Pengfei; Sun, Zhiyu; Zhou, Qiang

    2014-12-15

    Tungsten (W) is considered as promising candidate material for plasma facing components (PFCs) in future fusion reactors attributing to its many excellent properties. Current commercial pure tungsten material in accordance with the ITER specification can well fulfil the performance requirements, however, it has defects such as coarse grains, high ductile–brittle transition temperature (DBTT) and relatively low recrystallization temperature compared with its using temperature, which cannot meet the harsh wall loading requirement of future fusion reactor. Grain refinement has been reported to be effective in improving the thermophysical and mechanical properties of W. In this work, rare earth oxide (Y{sub 2}O{sub 3}/La{sub 2}O{sub 3}) and carbides (TiC/ZrC) were used as dispersion phases to refine W grains, and micro/nano composite technology with a process of “sol gel – heterogeneous precipitation – spray drying – hydrogen reduction – ordinary consolidation sintering” was invented to introduce these second-phase particles uniformly dispersed into W grains and grain-boundaries. Via this technology, fine-grain W materials with near-full density and relatively high mechanical properties compared with traditional pure W material were manufactured. Preliminary transient high-heat flux tests were performed to evaluate the thermal response under plasma disruption conditions, and the results show that the W materials prepared by micro/nano composite technology can endure high-heat flux of 200 MW/m{sup 2} (5 ms)

  6. Thermal compatibility of Sodium Nitrate/Expanded Perlite composite phase change materials

    International Nuclear Information System (INIS)

    Li, Ruguang; Zhu, Jiaoqun; Zhou, Weibing; Cheng, Xiaomin; Li, Yuanyuan

    2016-01-01

    Highlights: • Expanded Perlite/Sodium Nitrate composites hardly reported in thermal storage fields. • The thermal compatibility and adsorption of Expanded Perlite were investigated. • The thermo physic properties of composites were determined. • The thermal stability and long term enthalpy changes of composites were investigated. - Abstract: The present work focused on the preparation and characterization of a new thermal storage material applied in thermal energy management. X-ray diffraction (XRD) results showed that Expanded Perlite (EP) has a good thermal stability varying from 300 °C to 900 °C. Morphology of scanning electron microscopy (SEM) revealed that sodium nitrate is uniformly encapsulated and embedded in the three-dimensional network structure of EP. Fourier transform infrared (FT-IR) spectroscopy indicated that the EP is physically combined with the nitrate salt. Thermo-gravimetric analysis (TGA) and differential Scanning Calorimeter (DSC) indicated that the composites have good thermal stability. The adsorption capacity of loose EP was 213.21%. When the EP mass fraction varying from 10% to 60%, thermal conductivity decreased with the content of EP increased, and the highest thermal conductivity is 1.14 W (m K)"−"1 at 300 °C. SEM revealed the network structure of EP provided thermal conduction paths which enhanced the thermal conductivity of the composites. All results indicated that EP could be a good adsorption material to be applied in the thermal storage fields.

  7. Effects of pressure and temperature on thermal contact resistance between different materials

    Directory of Open Access Journals (Sweden)

    Zhao Zhe

    2015-01-01

    Full Text Available To explore whether pressure and temperature can affect thermal contact resistance, we have proposed a new experimental approach for measurement of the thermal contact resistance. Taking the thermal contact resistance between phenolic resin and carbon-carbon composites, cuprum, and aluminum as the examples, the influence of the thermal contact resistance between specimens under pressure is tested by experiment. Two groups of experiments are performed and then an analysis on influencing factors of the thermal contact resistance is presented in this paper. The experimental results reveal that the thermal contact resistance depends not only on the thermal conductivity coefficient of materials, but on the interfacial temperature and pressure. Furthermore, the thermal contact resistance between cuprum and aluminum is more sensitive to pressure and temperature than that between phenolic resin and carbon-carbon composites.

  8. Apparatus and method for transient thermal infrared spectrometry of flowable enclosed materials

    Science.gov (United States)

    McClelland, John F.; Jones, Roger W.

    1993-03-02

    A method and apparatus for enabling analysis of a flowable material enclosed in a transport system having an infrared transparent wall portion. A temperature differential is transiently generated between a thin surface layer portion of the material and a lower or deeper portion of the material sufficient to alter the thermal infrared emission spectrum of the material from the black-body thermal infrared emission spectrum of the material, and the altered thermal infrared emission spectrum is detected through the infrared transparent portion of the transport system while the altered thermal infrared emission spectrum is sufficiently free of self-absorption by the material of emitted infrared radiation. The detection is effected prior to the temperature differential propagating into the lower or deeper portion of the material to an extent such that the altered thermal infrared emission spectrum is no longer sufficiently free of self-absorption by the material of emitted infrared radiation. By such detection, the detected altered thermal infrared emission spectrum is indicative of characteristics relating to molecular composition of the material.

  9. Experimental Investigation of Thermal Conductivity of Concrete Containing Micro-Encapsulated Phase Change Materials

    DEFF Research Database (Denmark)

    Pomianowski, Michal Zbigniew; Heiselberg, Per; Jensen, Rasmus Lund

    2011-01-01

    in this article utilizes integration of the concrete and the microencapsulated Phase Change Material (PCM). PCM has the ability to absorb and release significant amounts of heat at a specific temperature range. As a consequence of admixing PCM to the concrete, new thermal properties like thermal conductivity...... and specific heat capacity have to be defined. This paper presents results from the measurements of the thermal conductivity of various microencapsulated PCM-concrete and PCM-cement-paste mixes. It was discovered that increase of the amount of PCM decreases the thermal conductivity of the concrete PCM mixture....... Finally, a theoretical calculation methodology of thermal conductivity for PCM-concrete mixes is developed....

  10. Thermal cycling and vibration response for PREPP concrete waste forms

    International Nuclear Information System (INIS)

    Nielson, R.M.; Welch, J.M.

    1983-06-01

    The Process Experimental Pilot Plant (PREPP) will process those transuranic wastes which do not satisfy the Waste Isolation Pilot Plant (WIPP) Waste Acceptance Criteria. Since these wastes will contain considerable quantities of combustible materials, incineration will be an integral part of the treatment process. Four basic types of PREPP ash wastes have been identified. The four types are designated high metal box waste, combustible waste, average waste, and inorganic sludge. In this process, the output of the incinerator is a mixture of ash and shredded noncombustible material (principally metals) which is separated into two sizes, -1/4 inch (under-size waste) and reverse arrow 1/4 inch (oversize waste). These wastes are solidified with hydraulic cement in 55-gallon drums. Simulated PREPP waste forms prepared by Colorado School of Mines Research Institute were subjected to thermal cycling and vibration testing to demonstrate compliance with the WIPP immobilization criterion. Although actual storage and transport conditions are expected to vary somewhat from those utilized in the testing protocol, the generation of only very small amounts of particulate suggests that the immobilization criterion should be routinely met for similar waste form formulations and production procedures. However, the behavior of waste forms containing significant quantities of off-gas scrubber sludge or considerably higher waste loadings may differ. Limited thermal cycling and vibration testing of prototype waste forms should be conducted if the final formulations or production methods used for actual waste forms differ appreciably from those tested in this study. If such testing is conducted, consideration should be given to designing the experiment to accommodate a larger number of thermal cycles more representative of the duration of storage expected

  11. Thermal response of an aeroassisted orbital-transfer vehicle with a conical drag brake

    Science.gov (United States)

    Pitts, W. C.; Murbach, M. S.

    1984-01-01

    As an aeroassisted orbital-transfer vehicle (AOTV) goes through an aerobraking maneuver, a significant amount of heat is generated. In this paper, the thermal response of a specific AOTV to this aerobrake heating is examined. The vehicle has a 70 deg, conical drag-brake heat shield attached to a cylindrical body which contains the payload. The heat shield is made of silica fabric. The heat-shield thickness is varied from that of a thin cloth to a 1.5-cm blanket. The fabric thickness, the radiation absorptivity of the vehicle surface materials, and radiation from the wake are all significant parameters in the thermal response to the heating produced by the braking maneuver. The maximum temperatures occur in the vicinity of the interface between the body and the conical heat shield.

  12. Thermal Response of an Aeroassisted Orbital Transfer Vehicle with a Conical Drag Brake

    Science.gov (United States)

    Pitts, W. C.; Murbach, M. S.

    1985-01-01

    As an aeroassisted orbital transfer vehicle (AOTV) goes through an aerobraking maneuver a significant amount of heat is generated. In this paper, the thermal response of a specific AOTV to this aerobrake heating is examined. The vehicle has a 70-deg, Conical drag-brake heat shield attached to a cylindrical body which contains the payload. The heat shield is made of ceramic fabric its thickness is varied from that of a thin cloth to a 1.5-cm blanket. The fabric thickness, the radiation absorptivity of the vehicle surface materials, and radiation from the wake are all significant parameters in the thermal response to the heating produced by the braking maneuver. The maximum temperatures occur In the vicinity of the interface between the body and the conical heat shield.

  13. Quantifying deforestation and forest degradation with thermal response.

    Science.gov (United States)

    Lin, Hua; Chen, Yajun; Song, Qinghai; Fu, Peili; Cleverly, James; Magliulo, Vincenzo; Law, Beverly E; Gough, Christopher M; Hörtnagl, Lukas; Di Gennaro, Filippo; Matteucci, Giorgio; Montagnani, Leonardo; Duce, Pierpaolo; Shao, Changliang; Kato, Tomomichi; Bonal, Damien; Paul-Limoges, Eugénie; Beringer, Jason; Grace, John; Fan, Zexin

    2017-12-31

    Deforestation and forest degradation cause the deterioration of resources and ecosystem services. However, there are still no operational indicators to measure forest status, especially for forest degradation. In the present study, we analysed the thermal response number (TRN, calculated by daily total net radiation divided by daily temperature range) of 163 sites including mature forest, disturbed forest, planted forest, shrubland, grassland, savanna vegetation and cropland. TRN generally increased with latitude, however the regression of TRN against latitude differed among vegetation types. Mature forests are superior as thermal buffers, and had significantly higher TRN than disturbed and planted forests. There was a clear boundary between TRN of forest and non-forest vegetation (i.e. grassland and savanna) with the exception of shrubland, whose TRN overlapped with that of forest vegetation. We propose to use the TRN of local mature forest as the optimal TRN (TRN opt ). A forest with lower than 75% of TRN opt was identified as subjected to significant disturbance, and forests with 66% of TRN opt was the threshold for deforestation within the absolute latitude from 30° to 55°. Our results emphasized the irreplaceable thermal buffer capacity of mature forest. TRN can be used for early warning of deforestation and degradation risk. It is therefore a valuable tool in the effort to protect forests and prevent deforestation. Copyright © 2017 Elsevier B.V. All rights reserved.

  14. FY 2017 – Thermal Aging Effects on Advanced Structural Materials

    Energy Technology Data Exchange (ETDEWEB)

    Li, Meimei [Argonne National Lab. (ANL), Argonne, IL (United States); Natesan, K [Argonne National Lab. (ANL), Argonne, IL (United States); Chen, Wei-Ying [Argonne National Lab. (ANL), Argonne, IL (United States)

    2017-08-01

    This report provides an update on the evaluation of the effect of thermal aging on tensile properties of existing laboratory-sized heats of Alloy 709 austenitic stainless steel and the completion of effort on the thermal aging effect on the tensile properties of optimized G92 ferritic-martensitic steel. The report is a Level 3 deliverable in FY17 (M3AT-17AN1602081), under the Work Package AT-17AN160208, “Advanced Alloy Testing - ANL” performed by the Argonne National Laboratory (ANL), as part of the Advanced Reactor Technologies Program.

  15. Supplier responsibility for nuclear material quality

    International Nuclear Information System (INIS)

    Stuart, P.S.; Dohna, A.E.

    1976-01-01

    Nuclear materials must be delivered by either the manufacturer or the distributor with objective, documented evidence that the material was manufactured, inspected, and tested by proven techniques performed by qualified personnel working to documented procedures. Measurement devices used for acceptance must be of proven accuracy. The material and all records must be identified for positive traceability as part of the quality history of the nuclear components, system, or structure in which the material was used. In conclusion, the nuclear material supplier must join the fabricator, the installer, and the user in effective implementation of the total systems approach to the application of quality assurance principles to all phases of procurement, fabrication, installation, and use of the safety-related components, systems, and structures in a nuclear power plant

  16. Standard Test Method for Oxyacetylene Ablation Testing of Thermal Insulation Materials

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2008-01-01

    1.1 This test method covers the screening of ablative materials to determine the relative thermal insulation effectiveness when tested as a flat panel in an environment of a steady flow of hot gas provided by an oxyacetylene burner. 1.2 This test method should be used to measure and describe the properties of materials, products, or assemblies in response to heat and flame under controlled laboratory conditions and should not be used to describe or appraise the fire hazard of materials, products, or assemblies under actual fire conditions. However, results of this test method may be used as elements of a fire risk assessment which takes into account all of the factors which are pertinent to an assessment of the fire hazard of a particular end use. 1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limi...

  17. An overview of high thermal conductive hot press forming die material development

    Directory of Open Access Journals (Sweden)

    A.R. Zulhishamuddin

    2015-12-01

    Full Text Available Most of the automotive industries are using high strength steel components, which are produced via hot press forming process. This process requires die material with high thermal conductivity that increases cooling rate during simultaneous quenching and forming stage. Due to the benefit of high quenching rate, thermal conductive die materials were produced by adding carbide former elements. This paper presents an overview of the modification of alloying elements in tool steel for high thermal conductivity properties by transition metal elements addition. Different types of manufacturing processes involved in producing high thermal conductive materials were discussed. Methods reported were powder metallurgy hot press, direct metal deposition, selective laser melting, direct metal laser sintering and spray forming. Elements likes manganese, nickel, molybdenum, tungsten and chromium were proven to increase thermal conductivity properties. Thermal conductivity properties resulted from carbide network presence in the steel microstructure. To develop feasible and low cost hot press forming die material, casting of Fe-based alloy with carbide former composition can be an option. Current thermal conductivity properties of hot press forming die material range between 25 and 66 W/m.K. The wide range of thermal conductivity varies the mechanical properties of the resulting components and lifetime of HPF dies.

  18. Composite material having high thermal conductivity and process for fabricating same

    Science.gov (United States)

    Colella, Nicholas J.; Davidson, Howard L.; Kerns, John A.; Makowiecki, Daniel M.

    1998-01-01

    A process for fabricating a composite material such as that having high thermal conductivity and having specific application as a heat sink or heat spreader for high density integrated circuits. The composite material produced by this process has a thermal conductivity between that of diamond and copper, and basically consists of coated diamond particles dispersed in a high conductivity metal, such as copper. The composite material can be fabricated in small or relatively large sizes using inexpensive materials. The process basically consists, for example, of sputter coating diamond powder with several elements, including a carbide forming element and a brazeable material, compacting them into a porous body, and infiltrating the porous body with a suitable braze material, such as copper-silver alloy, thereby producing a dense diamond-copper composite material with a thermal conductivity comparable to synthetic diamond films at a fraction of the cost.

  19. VII International scientific conference Radiation-thermal effects and processes in inorganic materials. Proceedings

    International Nuclear Information System (INIS)

    2010-01-01

    In the collection there are the reports of the VII International scientific conference and the VII All-Russian school-conference Radiation-thermal effects and processes in inorganic materials which were conducted on October 2-10, 2010, in Tomsk. The reports deal with new developments of charged particles high-intensity beam sources, high-temperature metrology of high-current beams and work materials, radiation-thermal stimulated effects and processes in inorganic materials, physical basics of technological processes, radiation-thermal technologies and equipment for their realization, allied branches of science and technology, specifically, nanotechnologies [ru

  20. Thermal capacitator design rationale. Part 1: Thermal and mechanical property data for selected materials potentially useful in thermal capacitor design and construction

    Science.gov (United States)

    Bailey, J. A.; Liao, C. K.

    1975-01-01

    The thermal properties of paraffin hydrocarbons and hydrocarbon mixtures which may be used as the phase change material (PCM) in thermal capacitors are discussed. The paraffin hydrocarbons selected for consideration are those in the range from C11H24 (n-Undecane) to C20H42 (n-Eicosane). A limited amount of data is included concerning other properties of paraffin hydrocarbons and the thermal and mechanical properties of several aluminum alloys which may find application as constructional materials. Data concerning the melting temperature, transition temperature, latent heat of fusion, heat of transition, specific heat, and thermal conductivity of pure and commercial grades of paraffin hydrocarbons are given. An index of companies capable of producing paraffin hydrocarbons and information concerning the availability of various grades (purity levels) is provided.

  1. Thermal conductivity of food materials at elevated temperatures

    NARCIS (Netherlands)

    Spiess, W.E.L.; Walz, E.; Nesvadba, P.; Morley, M.; Haneghem, van I.A.; Salmon, D.R.

    2001-01-01

    In order to expand the available information on thermal conductivity of foods, within the framework of COST Action 93, a collaborative study was organised. In the first step, typical food components (apple pulp, meat, olive oil, sodium caseinate, starch, tomato paste) were used as standards for

  2. Emanation thermal analysis of SiC based materials

    Czech Academy of Sciences Publication Activity Database

    Bálek, V.; Zeleňák, V.; Mitsuhashi, T.; Bakardjieva, Snejana; Šubrt, Jan; Haneda, H.

    2002-01-01

    Roč. 67, č. 1 (2002), s. 83-89 ISSN 1418-2874 R&D Projects: GA MŠk ME 180 Grant - others:EFDA(XE) TTMA-001 Institutional research plan: CEZ:AV0Z4032918 Keywords : emanation thermal analysis * SEM * SiC nanocomposites Subject RIV: CA - Inorganic Chemistry Impact factor: 0.598, year: 2002

  3. Aluminum and silicon based phase change materials for high capacity thermal energy storage

    International Nuclear Information System (INIS)

    Wang, Zhengyun; Wang, Hui; Li, Xiaobo; Wang, Dezhi; Zhang, Qinyong; Chen, Gang; Ren, Zhifeng

    2015-01-01

    Six compositions of aluminum (Al) and silicon (Si) based materials: 87.8Al-12.2Si, 80Al–20Si, 70Al–30Si, 60Al–40Si, 45Al–40Si–15Fe, and 17Al–53Si–30Ni (atomic ratio), were investigated for potentially high thermal energy storage (TES) application from medium to high temperatures (550–1200 °C) through solid–liquid phase change. Thermal properties such as melting point, latent heat, specific heat, thermal diffusivity and thermal conductivity were investigated by differential scanning calorimetry and laser flash apparatus. The results reveal that the thermal storage capacity of the Al–Si materials increases with increasing Si concentration. The melting point and latent heat of 45Al–40Si–15Fe and 17Al–53Si–30Ni are ∼869 °C and ∼562 J g −1 , and ∼1079 °C and ∼960 J g −1 , respectively. The measured thermal conductivity of Al–Si binary materials depend on Si concentration and is higher than 80 W m −1  K −1 from room temperature to 500 °C, which is almost two orders of magnitude higher than those of salts that are commonly used phase change material for thermal energy storage. - Highlights: • Six kinds of materials were investigated for thermal energy storage (550–1200 °C). • Partial melting of Al–Si materials show progressively changing temperatures. • Studied materials can be used in three different working temperature ranges. • Materials are potentially good candidates for thermal energy storage applications.

  4. Fabrication of Powder Metallurgy Pure Ti Material by Using Thermal Decomposition of TiH2

    Science.gov (United States)

    Mimoto, Takanori; Nakanishi, Nozomi; Umeda, Junko; Kondoh, Katsuyoshi

    Titanium (Ti) and titanium alloys have been interested as an engineering material because they are widely used across various industrial applications, for example, motorcycle, automotive and aerospace industries, due to their light weight, high specific strength and superior corrosion resistance. Ti materials are particularly significant for the aircraft using carbon/carbon (C/C) composites, for example, carbon fiber reinforced plastics (CFRP), because Ti materials are free from the problem of contact corrosion between C/C composites. However, the applications of Ti materials are limited because of their high cost. From a viewpoint of cost reduction, cost effective process to fabricate Ti materials is strongly required. In the present study, the direct consolidation of titanium hydride (TiH2) raw powders in solid-state was employed to fabricate pure Ti bulk materials by using thermal decomposition of TiH2. In general, the production cost of Ti components is expensive due to using commercially pure (CP) Ti powders after dehydrogenation. On the other hand, the novel process using TiH2 powders as starting materials is a promising low cost approach for powder metallurgy (P/M) Ti products. Furthermore, this new process is also attractive from a viewpoint of energy saving because the dehydrogenation is integrated into the sintering process. In this study, TiH2 raw powders were directly consolidated by conventional press technique at 600 MPa to prepare TiH2 powder compacted billets. To thermally decompose TiH2 and obtain sintered pure Ti billets, the TiH2 powder billets were heated in the integrated sintering process including dehydrogenation. The hot-extruded pure Ti material, which was heat treated at 1273 K for 180 min in argon gas atmosphere, showed tensile strength of 701.8 MPa and elongation of 27.1%. These tensile properties satisfied the requirements for JIS Ti Grade 4. The relationship between microstructures, mechanical properties response and heat treatment

  5. Magnetically responsive biological materials and their applications

    Czech Academy of Sciences Publication Activity Database

    Šafařík, Ivo; Pospíšková, K.; Baldíková, E.; Šafaříková, Miroslava

    2016-01-01

    Roč. 7, č. 4 (2016), s. 254-261 ISSN 0976-3961 Institutional support: RVO:60077344 Keywords : adsorbents * biological materials * carriers * magnetic modification * whole-cell biocatalyst Subject RIV: EI - Biotechnology ; Bionics

  6. Improving the thermal dimensional stability of flexible polymer composite backing materials for ultrasound transducers

    NARCIS (Netherlands)

    State, M.; Brands, P.J.; Vosse, van de F.N.

    2010-01-01

    Novel ultrasound backing materials based on polymer composites with improved dimensional stability and low coefficient of thermal expansion are being developed and analyzed. For this purpose a filled epoxy resin (Stycast1265), a commonly used backing material, was considered reference material and

  7. Thermal Conductivity on the Nanofluid of Graphene and Silver Nanoparticles Composite Material.

    Science.gov (United States)

    Myekhlai, Munkhshur; Lee, Taejin; Baatar, Battsengel; Chung, Hanshik; Jeong, Hyomin

    2016-02-01

    The composite material consisted of graphene (GN) and silver nanoparticles (AgNPs) has been essential topic in science and industry due to its unique thermal, electrical and antibacterial proper- ties. However, there are scarcity studies based on their thermal properties of nanofluids. Therefore, GN-AgNPs composite material was synthesized using facile and environment friendly method and further nanofluids were prepared by ultrasonication in this study. The morphological and structural investigations were carried out using scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray diffractometer (XRD) as well as ultra violet (UV)-visible spectroscopy. Furthermore, thermal conductivity measurements were performed for as-prepared nanofluids. As a result of thermal conductivity study, GN-AgNPs composite material was considerably enhanced the thermal conductivity of base fluid (water) by to 6.59% for the nanofluid (0.2 wt% GN and 0.4 wt% AgNPs).

  8. One-dimensional thermal response modeling of a transuranic foamed overpack system to a fire

    International Nuclear Information System (INIS)

    Suchsland, K.E.; Kwong, K.C.; Fretter, E.F.; Boyd, R.D.; Auerbach, I.; Yoshimura, H.R.

    1980-01-01

    Procedures have been established for modeling the thermal response of TRU container walls (TRUPACT) exposed to a fire environment. The effort included simulation testing and thermal modeling of the wall material. In this study, both testing and modeling were directed at determining a one-dimensional thermal model for undamaged polyurethane foam. The foam was assumed to exist in a nonoxidizing environment and was exposed to an almost step change in surface temperature. Results indicate that if the TRU waste container wall includes a polyurethane foam (64 kg/m 3 density) of thickness greater than 20 cm and the wall is otherwise undamaged, there will be no change in the waste content temperature where the container is subjected to a surface temperature as high as 1333 K for times less than 3600 s. Further improvements are needed in the thermal model to include transpiration, better estimates of the temperature-dependent thermal conductivity, effects of damaged wall structure and radiation absorption effects for the charged foam. 10 figures

  9. Comments on Thermal Physical Properties Testing Methods of Phase Change Materials

    Directory of Open Access Journals (Sweden)

    Jingchao Xie

    2013-01-01

    Full Text Available There is no standard testing method of the thermal physical properties of phase change materials (PCM. This paper has shown advancements in this field. Developments and achievements in thermal physical properties testing methods of PCM were commented, including differential scanning calorimetry, T-history measurement, the water bath method, and differential thermal analysis. Testing principles, advantages and disadvantages, and important points for attention of each method were discussed. A foundation for standardized testing methods for PCM was made.

  10. Some application of the thermal analysis technique to nuclear material process

    International Nuclear Information System (INIS)

    Xi Chongpu.

    1987-01-01

    This paper briefly described the thermal stability and phase transformation of Uranium Compounds as UF 4 , UO 2 F 2 , UO 2 -(NO 3 ) 2 , ADU, AUC, UO 3 and UO 2 . It proved that the thermal analysis finds extensive application in nuclear materials prodcution

  11. Protection and thermal management of thermoelectric generator system using phase change materials: An experimental investigation

    DEFF Research Database (Denmark)

    Ahmadi Atouei, Saeed; Rezaniakolaei, Alireza; Ranjbar, A.A.

    2018-01-01

    In most thermoelectric systems the thermal boundary conditions are transient, and thermal manage-ment of the system is critical to improve electrical performance of the system. In this study, effect of using phase change materials (PCM) to control the hot and cold side temperatures...

  12. Multi-scale modelling of thermal shock damage in refractory materials

    NARCIS (Netherlands)

    Özdemir, I.

    2009-01-01

    Refractories are high-temperature resistant materials used extensively in many engineering structures and assemblies in a wide spectrum of applications ranging from metallurgical furnace linings to thermal barrier coatings. Such structures are often exposed to severe thermal loading conditions in

  13. Ultraviolet and visible BRDF data on spacecraft thermal control and optical baffle materials

    Science.gov (United States)

    Viehmann, W.; Predmore, R. E.

    1987-01-01

    Bidirectional scattering functions of numerous optical baffle materials and of spacecraft thermal control coatings and surfaces are presented. Measurements were made at 254 nm and at 633 nm. The coatings and surfaces include high-reflectance white paints, low-reflectance optical blacks, thermal control blankets, and various conversion coatings on aluminum.

  14. Preparation and thermal properties characterization of carbonate salt/carbon nanomaterial composite phase change material

    International Nuclear Information System (INIS)

    Tao, Y.B.; Lin, C.H.; He, Y.L.

    2015-01-01

    Highlights: • Nanocomposite phase change materials were prepared and characterized. • Larger specific surface area is more efficient to enhance specific heat. • Columnar structure is more efficient to enhance thermal conductivity. • Thermal conductivity enhancement is the key. • Single walled carbon nanotube is the optimal nanomaterial additive. - Abstract: To enhance the performance of high temperature salt phase change material, four kinds of carbon nanomaterials with different microstructures were mixed into binary carbonate eutectic salts to prepare carbonate salt/nanomaterial composite phase change material. The microstructures of the nanomaterial and composite phase change material were characterized by scanning electron microscope. The thermal properties such as melting point, melting enthalpy, specific heat, thermal conductivity and total thermal energy storage capacity were characterized. The results show that the nanomaterial microstructure has great effects on composite phase change material thermal properties. The sheet structure Graphene is the best additive to enhance specific heat, which could be enhanced up to 18.57%. The single walled carbon nanotube with columnar structure is the best additive to enhance thermal conductivity, which could be enhanced up to 56.98%. Melting point increases but melting enthalpy decreases with nanomaterial specific surface area increase. Although the additives decrease the melting enthalpy of composite phase change material, they also enhance the specific heat. As a combined result, the additives have little effects on thermal energy storage capacity. So, for phase change material performance enhancement, more emphasis should be placed on thermal conductivity enhancement and single walled carbon nanotube is the optimal nanomaterial additive

  15. Thermal imaging during ballistic testing of armour materials

    NARCIS (Netherlands)

    Carton, E.P.; Roebroeks, G.H.J.J.

    2013-01-01

    During the interaction between a projectile and a target material the kinetic energy of the projectile is transferred into elastic and plastic deformation of both the projectile and target materials. Using a rigid penetrator the loss in kinetic energy is fully converted into energy absorbed by the

  16. Standard test method for linear thermal expansion of glaze frits and ceramic whiteware materials by the interferometric method

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1995-01-01

    1.1 This test method covers the interferometric determination of linear thermal expansion of premelted glaze frits and fired ceramic whiteware materials at temperatures lower than 1000°C (1830°F). 1.2 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  17. Multi-Functional Stimuli-Responsive Materials

    Data.gov (United States)

    National Aeronautics and Space Administration — Supramolecular polymers based on non-covalent interactions can display a wide array of stimuli-responsive attributes. They can be tailored to change shape, actuate...

  18. Review on factors influencing thermal conductivity of concrete incorporating various type of waste materials

    Science.gov (United States)

    Misri, Z.; Ibrahim, M. H. W.; Awal, A. S. M. A.; Desa, M. S. M.; Ghadzali, N. S.

    2018-04-01

    Concrete is well-known as a construction material which is widely used in building and infrastructure around the world. However, its widespread use has affected the reduction of natural resources. Hence, many approached have been made by researchers to study the incorporation of waste materials in concrete as a substitution for natural resources besides reducing waste disposal problems. Concrete is basically verified by determining its properties; strengths, permeability, shrinkage, durability, thermal properties etc. In various thermal properties of concrete, thermal conductivity (TC) has received a large amount of attention because it is depend upon the composition of concrete. Thermal conductivity is important in building insulation to measure the ability of a material to transfer heat. The aim of this paper is to discuss the methods and influence factors of TC of concrete containing various type of waste materials.

  19. Utilization of Self-Healing Materials in Thermal Protection System Applications

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed project is the Utilization of Self-Healing Materials for Thermal Protection System (TPS) Applications. Currently, the technology for repairing TPS from...

  20. Viscoelastic response of hydrogel materials at finite strains

    OpenAIRE

    Skovly, Martin Johannessen

    2015-01-01

    Hydrogel materials are very soft materials consisting of polymer networks and solvent molecules. The materials may exhibit large volume changes depending on its external chemical and mechanical environment and have viscoelastic properties which is common for many polymeric materials. In order to model the material response with the finite element method, a hydrogel constitutive model have been combined with finite viscoelastic theory and the resulting viscoelastic hydrogel constitutive model ...

  1. Investigation of Thermal Interface Materials Using Phase-Sensitive Transient Thermoreflectance Technique: Preprint

    Energy Technology Data Exchange (ETDEWEB)

    Feng, X.; King, C.; DeVoto, D.; Mihalic, M.; Narumanchi, S.

    2014-08-01

    With increasing power density in electronics packages/modules, thermal resistances at multiple interfaces are a bottleneck to efficient heat removal from the package. In this work, the performance of thermal interface materials such as grease, thermoplastic adhesives and diffusion-bonded interfaces are characterized using the phase-sensitive transient thermoreflectance technique. A multi-layer heat conduction model was constructed and theoretical solutions were derived to obtain the relation between phase lag and the thermal/physical properties. This technique enables simultaneous extraction of the contact resistance and bulk thermal conductivity of the TIMs. With the measurements, the bulk thermal conductivity of Dow TC-5022 thermal grease (70 to 75 um bondline thickness) was 3 to 5 W/(m-K) and the contact resistance was 5 to 10 mm2-K/W. For the Btech thermoplastic material (45 to 80 μm bondline thickness), the bulk thermal conductivity was 20 to 50 W/(m-K) and the contact resistance was 2 to 5 mm2-K/W. Measurements were also conducted to quantify the thermal performance of diffusion-bonded interface for power electronics applications. Results with the diffusion-bonded sample showed that the interfacial thermal resistance is more than one order of magnitude lower than those of traditional TIMs, suggesting potential pathways to efficient thermal management.

  2. Thermal Stability Test of Sugar Alcohols as Phase Change Materials for Medium Temperature Energy Storage Application

    OpenAIRE

    Solé, Aran; Neumann, Hannah; Niedermaier, Sophia; Cabeza, Luisa F.; Palomo, Elena

    2014-01-01

    Sugar alcohols are potential phase change materials candidates as they present high phase change enthalpy values, are non-toxic and low cost products. Three promising sugar-alcohols were selected: D-mannitol, myo-inositol and dulcitol under high melting enthalpy and temperature criterion. Thermal cycling tests were performed to study its cycling stability which can be determining when selecting the suitable phase change material. D-mannitol and dulcitol present poor thermal stability...

  3. Ultra-low thermal conductivities of hot-pressed attapulgite and its potential as thermal insulation material

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Yuan; Ren, Zhifeng, E-mail: bohr123@163.com, E-mail: zren@uh.edu [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Wang, Xiuzhang [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Hubei Key Laboratory of Pollutant Analysis and Reuse Technology and School of Physics and Electronic Science, Hubei Normal University, Huangshi, Hubei 435002 (China); Wang, Yumei [Department of Physics and TcSUH, University of Houston, Houston, Texas 77204 (United States); Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China); Tang, Zhongjia; Makarenko, Tatyana; Guloy, Arnold [Department of Chemistry, University of Houston, Houston, Texas 77204 (United States); Zhang, Qinyong, E-mail: bohr123@163.com, E-mail: zren@uh.edu [Center for Advanced Materials and Energy, Xihua University, Chengdu, Sichuan 610039 (China)

    2016-03-07

    In the past, there have been very few reports on thermal properties of attapulgite which is a widely used clay mineral. In this work, we report on extremely low thermal conductivities in attapulgite samples synthesized by hot-pressing. Attapulgite powder was hot-pressed at different temperatures into bulk samples, and a systematic study was conducted on the microstructures and thermal properties. Differential scanning calorimetry analysis shows that hot-pressing induces a rapid dehydration of the attapulgite powders. X-ray diffraction data and scanning/transmission electron microscopy reveal that the hot-pressed attapulgite features high porosity and complex microstructures, including an amorphous phase. As a result, the hot-pressed attapulgite exhibits thermal conductivity less than 2.5 W m{sup −1} K{sup −1} up to 600 °C. For one sample with porosity of 45.7%, the thermal conductivity is as low as 0.34 W m{sup −1} K{sup −1} at 50 °C. This suggests the potential of hot-pressed attapulgite as a candidate for thermal barrier materials.

  4. Experimental evaluation of the thermal properties of two tissue equivalent phantom materials.

    Science.gov (United States)

    Craciunescu, O I; Howle, L E; Clegg, S T

    1999-01-01

    Tissue equivalent radio frequency (RF) phantoms provide a means for measuring the power deposition of various hyperthermia therapy applicators. Temperature measurements made in phantoms are used to verify the accuracy of various numerical approaches for computing the power and/or temperature distributions. For the numerical simulations to be accurate, the electrical and thermal properties of the materials that form the phantom should be accurately characterized. This paper reports on the experimentally measured thermal properties of two commonly used phantom materials, i.e. a rigid material with the electrical properties of human fat, and a low concentration polymer gel with the electrical properties of human muscle. Particularities of the two samples required the design of alternative measuring techniques for the specific heat and thermal conductivity. For the specific heat, a calorimeter method is used. For the thermal diffusivity, a method derived from the standard guarded comparative-longitudinal heat flow technique was used for both materials. For the 'muscle'-like material, the thermal conductivity, density and specific heat at constant pressure were measured as: k = 0.31 +/- 0.001 W(mK)(-1), p = 1026 +/- 7 kgm(-3), and c(p) = 4584 +/- 107 J(kgK)(-1). For the 'fat'-like material, the literature reports on the density and specific heat such that only the thermal conductivity was measured as k = 0.55 W(mK)(-1).

  5. Analysis of the Thermal Shielding Properties of Camouflage Materials

    National Research Council Canada - National Science Library

    Bennett, John G; Polsen, Erik S

    2007-01-01

    .... The outer surface of each panel was thermostatically controlled to the same temperature. The camouflage material covered one of the panels, while the other, uncovered, panel acted as the baseline...

  6. Dust Erosion Performance of Candidate Motorcase Thermal Protection Materials.

    Science.gov (United States)

    1980-03-10

    REFERENCE DESCRIPTION SOURCE NUMBER 4.01 NBR B. F. Goodrich Aerospace and Defense Products (Nitrile butadiene 500 South Main Street rubber ) Akron, Ohio...material degradation occurs. 5.3 BALLISTIC RANGES Ballistic ranges are widely used for reentry erosion testing for two reasons: 1) no other type of facility...DET REFERENCE OTHER COMMENTS NUMBER DESIGNATION 2002 KEVLAR-EPOXY STAGE 3 MOTORCASE MATERIAL MOTORCAS E 2402 NBR 68 2403 NBR 69 2404 NBR -19709-6A (60

  7. Thermal characterization of radiation processed contact lens material

    International Nuclear Information System (INIS)

    Varshney, L.; Choughule, S.V.

    1998-01-01

    Differential scanning calorimetry (DSC), thermomechanical analysis (TMA) and thermogravimetry analysis (TGA) were used to characterize radiation processed contact lens gel material of 2-hydroxy ethyl methacrylate(HEMA). DSC revealed two types of water in the gels. DSC and TGA in combination were used to quantitate the percentage of different types of the water in the gel material. Temperature expansion coefficients values indicate more dimensions stability in the radiation processed lenses of similar water contents. (author)

  8. Performance of buffer material under radiation and thermal conditions

    International Nuclear Information System (INIS)

    Zhao Shuaiwei; Yang Zhongtian; Liu Wei

    2012-01-01

    Bentonite is generally selected as backfill and buffer material for repositories in the world. Radiation and heat release is the intrinsic properties of high level radioactive waste. This paper made a preliminary research on foreign literature about performance of the engineering barrier material under radiation and at higher temperatures (e. g. above 100℃). As our current research is just budding in this area, we need to draw lessons from foreign experience and methods. (authors)

  9. Osmotic heat engine using thermally responsive ionic liquids

    KAUST Repository

    Zhong, Yujiang

    2017-07-11

    The osmotic heat engine (OHE) is a promising technology for converting low grade heat to electricity. Most of the existing studies have focused on thermolytic salt systems. Herein, for the first time, we proposed to use thermally responsive ionic liquids (TRIL) that have either an upper critical solution temperature (UCST) or lower critical solution temperature (LCST) type of phase behavior as novel thermolytic osmotic agents. Closed-loop TRIL-OHEs were designed based on these unique phase behaviors to convert low grade heat to work or electricity. Experimental studies using two UCST-type TRILs, protonated betaine bis(trifluoromethyl sulfonyl)imide ([Hbet][Tf2N]) and choline bis(trifluoromethylsulfonyl)imide ([Choline][Tf2N]) showed that (1) the specific energy of the TRIL-OHE system could reach as high as 4.0 times that of the seawater and river water system, (2) the power density measured from a commercial FO membrane reached up to 2.3 W/m2, and (3) the overall energy efficiency reached up to 2.6% or 18% of the Carnot efficiency at no heat recovery and up to 10.5% or 71% of the Carnet efficiency at 70% heat recovery. All of these results clearly demonstrated the great potential of using TRILs as novel osmotic agents to design high efficient OHEs for recovery of low grade thermal energy to work or electricity.

  10. Calculation of the thermal stress and thermal resistance of anisotropic materials. II

    Energy Technology Data Exchange (ETDEWEB)

    Krivko, A I; Epishin, A I; Svetlov, I L; Samoilov, A I; Sukhanov, N N

    1989-04-01

    The stressed state in a wedge and in a family of plates cut from single-crystal ingots of 40 axial orientations is analyzed. It is shown that, in contrast to the case of the wedge, the value of the thermal stress tensor components in the plates depends substantially not only on the axial crystallographic orientation but also on the azimuthal orientation. Requirements on the crystallographic orientation of simple single-crystal parts of plate or wedge type are formulated with the aim of decreasing the detrimental effects of thermal stresses. The correctness of the calculations is confirmed by results of thermal fatigue tests of hollow prismatic specimens, i.e., blade simulators with 001, 011, and 111 axial orientations.

  11. Thermal diffusion of water vapour in porous materials: fact or fiction?

    DEFF Research Database (Denmark)

    Janssen, Hans

    2011-01-01

    diffusion. Thermal diffusion opponents, on the other hand, assert that these thermal transports are negligibly small. This paper resolves that contradiction. A critical analysis of the investigations supporting the occurrence of thermal diffusion reveals that all are flawed. A correct reinterpretation...... its negligible magnitude. It can in conclusion be stated that thermal diffusion is of no importance for building science applications, leaving vapour pressure as the sole significant transport potential for the diffusion of water vapour in porous materials. (C) 2010 Elsevier Ltd. All rights reserved....

  12. Thermal Response Analyses of Spherical LPG Storage Tank

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hsijen.; Lin, Mannhsing.; Chao, Fuyuan

    1999-02-01

    Liquefied petroleum gas (LPG) is a very important fuel and chemical feed stock as well; however, the hydrocarbon has been involved in many major fires and explosions. One of these accidents is boiling-liquid, expanding-vapor explosion (BLEVE). It is a phenomenon that results from the sudden release form confinement of a liquid at a temperature above its atmospheric-pressure boiling point. The sudden decrease in pressure results in the explosive vaporization of a fraction of the liquid and a cloud of vapor and mist with the accompanying blast effects. Most BLEVEs involve flammable liquids, and most BELEVE releases are ignited by a surrounding fire and result in a fireball. The primary objective of this paper is to develop a computer model in order to determine the thermal response of a spherical LPG tank involved in fire engulfment accidents. The assessment of the safety spacing between tanks was also discussed. (author)

  13. Cross-section of single-crystal materials used as thermal neutron filters

    International Nuclear Information System (INIS)

    Adib, M.

    2005-01-01

    Transmission properties of several single crystal materials important for neutron scattering instrumentation are presented. A computer codes are developed which permit the calculation of thermal diffuse and Bragg-scattering cross-sections of silicon., and sapphire as a function of material's constants, temperature and neutron energy, E, in the range 0.1 MeV .A discussion of the use of their single-crystal as a thermal neutron filter in terms of the optimum crystal thickness, mosaic spread, temperature, cutting plane and tuning for efficient transmission of thermal-reactor neutrons is given

  14. New method of thermal cycling stability test of phase change material

    Directory of Open Access Journals (Sweden)

    Putra Nandy

    2017-01-01

    Full Text Available Phase Change Material (PCM is the most promising material as thermal energy storage nowadays. As thermal energy storage, examination on endurance of material for long-term use is necessary to be carried out. Therefore, thermal cycling test is performed to ensure thermal stability of PCM. This study have found a new method on thermal cycling test of PCM sample by using thermoelectric as heating and cooling element. RT 22 HC was used as PCM sample on this thermal cycling test. The new method had many advantages compared to some references of the same test. It just needed a small container for PCM sample. The thermoelectric could release heat to PCM sample and absorb heat from PCM sample uniformly, respectively, was called as heating and cooling process. Hence, thermoelectric had to be supported by a relay control device to change its polarity so it could heat and cool PCM sample alternately and automatically. On the other hand, the thermoelectric was cheap, easy to be found and available in markets. It can be concluded that new method of thermal cycling test by using thermoelectric as source of heating and cooling can be a new reference for performing thermal cycling test on PCM.

  15. Lightweight Ablative and Ceramic Thermal Protection System Materials for NASA Exploration Systems Vehicles

    Science.gov (United States)

    Valentine, Peter G.; Lawrence, Timothy W.; Gubert, Michael K.; Milos, Frank S.; Kiser, James D.; Ohlhorst, Craig W.; Koenig, John R.

    2006-01-01

    As a collaborative effort among NASA Centers, the "Lightweight Nonmetallic Thermal Protection Materials Technology" Project was set up to assist mission/vehicle design trade studies, to support risk reduction in thermal protection system (TPS) material selections, to facilitate vehicle mass optimization, and to aid development of human-rated TPS qualification and certification plans. Missions performing aerocapture, aerobraking, or direct aeroentry rely on advanced heatshields that allow reductions in spacecraft mass by minimizing propellant requirements. Information will be presented on candidate materials for such reentry approaches and on screening tests conducted (material property and space environmental effects tests) to evaluate viable candidates. Seventeen materials, in three classes (ablatives, tiles, and ceramic matrix composites), were studied. In additional to physical, mechanical, and thermal property tests, high heat flux laser tests and simulated-reentry oxidation tests were performed. Space environmental effects testing, which included exposures to electrons, atomic oxygen, and hypervelocity impacts, was also conducted.

  16. Multiscale Modeling of Carbon/Phenolic Composite Thermal Protection Materials: Atomistic to Effective Properties

    Science.gov (United States)

    Arnold, Steven M.; Murthy, Pappu L.; Bednarcyk, Brett A.; Lawson, John W.; Monk, Joshua D.; Bauschlicher, Charles W., Jr.

    2016-01-01

    Next generation ablative thermal protection systems are expected to consist of 3D woven composite architectures. It is well known that composites can be tailored to achieve desired mechanical and thermal properties in various directions and thus can be made fit-for-purpose if the proper combination of constituent materials and microstructures can be realized. In the present work, the first, multiscale, atomistically-informed, computational analysis of mechanical and thermal properties of a present day - Carbon/Phenolic composite Thermal Protection System (TPS) material is conducted. Model results are compared to measured in-plane and out-of-plane mechanical and thermal properties to validate the computational approach. Results indicate that given sufficient microstructural fidelity, along with lowerscale, constituent properties derived from molecular dynamics simulations, accurate composite level (effective) thermo-elastic properties can be obtained. This suggests that next generation TPS properties can be accurately estimated via atomistically informed multiscale analysis.

  17. Die attach dimension and material on thermal conductivity study for high power COB LED

    Science.gov (United States)

    Sarukunaselan, K.; Ong, N. R.; Sauli, Z.; Mahmed, N.; Kirtsaeng, S.; Sakuntasathien, S.; Suppiah, S.; Alcain, J. B.; Retnasamy, V.

    2017-09-01

    High power LED began to gain popularity in the semiconductor market due to its efficiency and luminance. Nonetheless, along with the increased in efficiency, there was an increased in the junction temperature too. The alleviating junction temperature is undesirable since the performances and lifetime will be degraded over time. Therefore, it is crucial to solve this thermal problem by maximizing the heat dissipation to the ambience. Improvising the die attach (DA) layer would be the best option because this layer is sandwiched between the chip (heat source) and the substrate (channel to the ambient). In this paper, the impact of thickness and thermal conductivity onto the junction temperature and Von Mises stress is analyzed. Results obtained showed that the junction temperature is directly proportional to the thickness but the stress was inversely proportional to the thickness of the DA. The thermal conductivity of the materials did affect the junction temperature as there was not much changes once the thermal conductivity reached 20W/mK. However, no significant changes were observed on the Von Mises stress caused by the thermal conductivity. Material with the second highest thermal conductivity had the lowest stress, whereas the highest conductivity material had the highest stress value at 20 µm. Overall, silver sinter provided the best thermal dissipation compared to the other materials.

  18. Preparation, microstructure and thermal properties of Mg−Bi alloys as phase change materials for thermal energy storage

    International Nuclear Information System (INIS)

    Fang, Dong; Sun, Zheng; Li, Yuanyuan; Cheng, Xiaomin

    2016-01-01

    Highlights: • The microstructure and thermal properties of Mg−Bi alloys are determined. • The relationship between melting enthalpies and phase composition are studied. • The activation energy of Mg−54%Bi alloy is calculated by multiple DSC technology. • Mg−54%Bi alloy is proposed as a phase change material at high (>420 °C) temperature. - Abstract: Comparing with Al-based phase change material, Mg-based phase change material is getting more and more attention due to its high corrosion resistance with encapsulation materials based on iron. This study focuses on the characterization of Mg−36%Bi, Mg−54%Bi and Mg−60%Bi (wt. %) alloys as phase change materials for thermal energy storage at high temperature. The phase compositions, microstructure and phase change temperatures were investigated by X-ray diffusion (XRD), electron probe micro-analysis (EPMA) and differential scanning calorimeter (DSC) analysis, respectively. The results indicates that the microstructure of Mg−36%Bi and Mg−54%Bi alloys are mainly composed of α-Mg matrix and α-Mg + Mg_3Bi_2 eutectic phases, Mg−60%Bi alloy are mainly composed of the Mg_3Bi_2 phase and α-MgMg_3Bi_2 eutectic phases. The melting enthalpies of Mg−36%Bi, Mg−54%Bi and Mg−60%Bi alloys are 138.2, 180.5 and 48.7 J/g, with the phase change temperatures of 547.6, 546.3 and 548.1 °C, respectively. The Mg−54%Bi alloy has the highest melting enthalpy in three alloys. The main reason may be that it has more proportion of α-Mg + Mg_3Bi_2 eutectic phases. The thermal expansion of three alloys increases with increasing temperature. The values of the thermal conductivity decrease with increasing Bi content. Besides, the activation energy of Mg−54%Bi was calculated by multiple DSC technology.

  19. Novel dynamic thermal characterization of multifunctional concretes with microencapsulated phase change materials

    Science.gov (United States)

    Pisello, Anna Laura; Fabiani, Claudia; D'Alessandro, Antonella; Cabeza, Luisa F.; Ubertini, Filippo; Cotana, Franco

    2017-04-01

    Concrete is widely applied in the construction sector for its reliable mechanical performance, its easiness of use and low costs. It also appears promising for enhancing the thermal-energy behavior of buildings thanks to its capability to be doped with multifunctional fillers. In fact, key studies acknowledged the benefits of thermally insulated concretes for applications in ceilings and walls. At the same time, thermal capacity also represents a key property to be optimized, especially for lightweight constructions. In this view, Thermal-Energy Storage (TES) systems have been recently integrated into building envelopes for increasing thermal inertia. More in detail, numerical experimental investigations showed how Phase Change materials (PCMs), as an acknowledged passive TES strategy, can be effectively included in building envelope, with promising results in terms of thermal buffer potentiality. In particular, this work builds upon previous papers aimed at developing the new PCM-filled concretes for structural applications and optimized thermalenergy efficiency, and it is focused on the development of a new experimental method for testing such composite materials in thermal-energy dynamic conditions simulated in laboratory by exposing samples to environmentally controlled microclimate while measuring thermal conductivity and diffusivity by means of transient plane source techniques. The key findings show how the new composites are able to increasingly delay the thermal wave with increasing the PCM concentration and how the thermal conductivity varies during the course of the phase change, in both melting and solidification processes. The new analysis produces useful findings in proposing an effective method for testing composite materials with adaptive thermal performance, much needed by the scientific community willing to study building envelopes dynamics.

  20. Combinatory Models for Predicting the Effective Thermal Conductivity of Frozen and Unfrozen Food Materials

    Directory of Open Access Journals (Sweden)

    K. S. Reddy

    2010-01-01

    Full Text Available A model to predict the effective thermal conductivity of heterogeneous materials is proposed based on unit cell approach. The model is combined with four fundamental effective thermal conductivity models (Parallel, Series, Maxwell-Eucken-I, and Maxwell-Eucken-II to evolve a unifying equation for the estimation of effective thermal conductivity of porous and nonporous food materials. The effect of volume fraction (ν on the structure composition factor (ψ of the food materials is studied. The models are compared with the experimental data of various foods at the initial freezing temperature. The effective thermal conductivity estimated by the Maxwell-Eucken-I + Present model shows good agreement with the experimental data with a minimum average deviation of ±8.66% and maximum deviation of ±42.76% of Series + Present Model. The combined models have advantages over other empirical and semiempirical models.

  1. Giant Thermal Expansion in 2D and 3D Cellular Materials.

    Science.gov (United States)

    Zhu, Hanxing; Fan, Tongxiang; Peng, Qing; Zhang, Di

    2018-03-25

    When temperature increases, the volume of an object changes. This property was quantified as the coefficient of thermal expansion only a few hundred years ago. Part of the reason is that the change of volume due to the variation of temperature is in general extremely small and imperceptible. Here, abnormal giant linear thermal expansions in different types of two-ingredient microstructured hierarchical and self-similar cellular materials are reported. The cellular materials can be 2D or 3D, and isotropic or anisotropic, with a positive or negative thermal expansion due to the convex or/and concave shape in their representative volume elements respectively. The magnitude of the thermal expansion coefficient can be several times larger than the highest value reported in the literature. This study suggests an innovative approach to develop temperature-sensitive functional materials and devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  2. A comparative study of the thermal interface materials with graphene and boron nitride fillers

    Science.gov (United States)

    Kargar, F.; Salgado, R.; Legedza, S.; Renteria, J.; Balandin, A. A.

    2014-09-01

    We report the results of an experimental study that compares the performance of graphene and boron nitride flakes as fillers in the thermal interface materials. The thickness of both fillers varied from a single atomic plane to about a hundred. The measurements have been conducted using a standard TIM tester. Our results show that the addition of a small fraction of graphene (f=4 wt%) to a commercial thermal interface material increases the resulting apparent thermal conductivity substantially stronger than the addition of boron nitride. The obtained data suggest that graphene and fewlayer graphene flakes couple better to the matrix materials than the boron nitride fillers. A combination of both fillers can be used to increase the thermal conductivity while controlling the electrical conduction.

  3. A Thermally Re-mendable Cross-Linked Polymeric Material

    Science.gov (United States)

    Chen, Xiangxu; Dam, Matheus A.; Ono, Kanji; Mal, Ajit; Shen, Hongbin; Nutt, Steven R.; Sheran, Kevin; Wudl, Fred

    2002-03-01

    We have developed a transparent organic polymeric material that can repeatedly mend or ``re-mend'' itself under mild conditions. The material is a tough solid at room temperature and below with mechanical properties equaling those of commercial epoxy resins. At temperatures above 120°C, approximately 30% (as determined by solid-state nuclear magnetic resonance spectroscopy) of ``intermonomer'' linkages disconnect but then reconnect upon cooling, This process is fully reversible and can be used to restore a fractured part of the polymer multiple times, and it does not require additional ingredients such as a catalyst, additional monomer, or special surface treatment of the fractured interface.

  4. Dense Vertically Aligned Copper Nanowire Composites as High Performance Thermal Interface Materials.

    Science.gov (United States)

    Barako, Michael T; Isaacson, Scott G; Lian, Feifei; Pop, Eric; Dauskardt, Reinhold H; Goodson, Kenneth E; Tice, Jesse

    2017-12-06

    Thermal interface materials (TIMs) are essential for managing heat in modern electronics, and nanocomposite TIMs can offer critical improvements. Here, we demonstrate thermally conductive, mechanically compliant TIMs based on dense, vertically aligned copper nanowires (CuNWs) embedded into polymer matrices. We evaluate the thermal and mechanical characteristics of 20-25% dense CuNW arrays with and without polydimethylsiloxane infiltration. The thermal resistance achieved is below 5 mm 2 K W -1 , over an order of magnitude lower than commercial heat sink compounds. Nanoindentation reveals that the nonlinear deformation mechanics of this TIM are influenced by both the CuNW morphology and the polymer matrix. We also implement a flip-chip bonding protocol to directly attach CuNW composites to copper surfaces, as required in many thermal architectures. Thus, we demonstrate a rational design strategy for nanocomposite TIMs that simultaneously retain the high thermal conductivity of aligned CuNWs and the mechanical compliance of a polymer.

  5. Thermal properties of clay-based buffer materials for a nuclear fuel waste disposal vault

    International Nuclear Information System (INIS)

    Radhakrishna, H.S.

    1984-06-01

    The thermal properties of three types of bentonite clay, one illite-rich shale and one kaolin mixed with crushed granite were investigated. Thermal conductivity measurements were made over a range of mix proportions, moisture content, density and ambient temperature using the transient heat-probe method. The effects of thermal drying in the buffer zone prior to water uptake were investigated by means of laboratory-scale heater experiments. Illite-rich shale (Sealbond) and kaolin exhibited better compactability and thermal conductivity than the bentonite clays. The thermal conductivity of all types of clay buffers showed a high degree of moisture dependency and relatively no effect due to elevated temperature under high fluid pressure conditions. Bentonite buffers compacted to a dry density of 1200 to 1400 kg/m 3 showed extensive cracking due to differential shrinkage. Addition of crushed granite, and/or compaction to a higher density, reduced the thermal cracking of the buffer material

  6. The usage of phase change materials in fire fighter protective clothing: its effect on thermal protection

    Science.gov (United States)

    Zhao, Mengmeng

    2017-12-01

    The thermal protective performance of the fire fighter protective clothing is of vital importance for fire fighters. In the study fabrics treated by phase change materials (PCMs) were applied in the multi-layered fabrics of the fire fighter protective clothing ensemble. The PCM fabrics were placed at the different layers of the clothing and their thermal protective performance were measured by a TPP tester. Results show that with the application of the PCM fabrics the thermal protection of the multi-layered fabrics was greatly increased. The time to reach a second degree burn was largely reduced. The location of the PCM fabrics at the different layers did not affect much on the thermal protective performance. The higher amount of the PCM adds on, the higher thermal protection was brought. The fabrics with PCMs of a higher melting temperature could contribute to higher thermal protection.

  7. Recent progresses and achievements in photovoltaic-phase change material technology: A review with special treatment on photovoltaic thermal-phase change material systems

    International Nuclear Information System (INIS)

    Islam, M.M.; Pandey, A.K.; Hasanuzzaman, M.; Rahim, N.A.

    2016-01-01

    Highlights: • Broad summary of phase change materials based cooling for photovoltaic modules. • Compendium on phase change materials that are mostly used in photovoltaic systems. • Extension of heat availability period by 75–100% with phase change material. • Heat storage potential improves by 33–50% more with phase change material. • Future trend and move in photovoltaic thermal research. - Abstract: This communication lays out an appraisal on the recent works of phase change materials based thermal management techniques for photovoltaic systems with special focus on the so called photovoltaic thermal-phase change material system. Attempt has also been made to draw wide-ranging classification of both photovoltaic and photovoltaic thermal systems and their conventional cooling or heat harvesting methods developed so far so that feasible phase change materials application area in these systems can be pointed out. In addition, a brief literature on phase change materials with particular focus on their solar application has also been presented. Overview of the researches and studies establish that using phase change materials for photovoltaic thermal control is technically viable if some issues like thermal conductivity or phase stability are properly addressed. The photovoltaic thermal-phase change material systems are found to offer 33% (maximum 50%) more heat storage potential than the conventional photovoltaic-thermal water system and that with 75–100% extended heat availability period and around 9% escalation in output. Reduction in temperature attained with photovoltaic thermal-phase change material system is better than that with regular photovoltaic-thermal water system, too. Studies also show the potential of another emerging technology of photovoltaic thermal-microencapsulated phase change material system that makes use of microencapsulated phase change materials in thermal regulation. Future focus areas on photovoltaic thermal-phase change

  8. Differences between young adults and elderly in thermal comfort, productivity and thermal physiology in response to a moderate temperature drift

    DEFF Research Database (Denmark)

    Schellen, Lisje; Lichtenbelt, Wouter van Marken; Loomans, Marcel

    2010-01-01

    thermal condition differ between young adults and elderly. There is a lack of studies that describe the effect of aging on thermal comfort and productivity during a moderate temperature drift. In this study, the effect of a moderate temperature drift on physiological responses, thermal comfort......Results from naturally ventilated buildings show that allowing the indoor temperature to drift does not necessarily result in thermal discomfort and may allow for a reduction in energy use. However, for stationary conditions, several studies indicate that the thermal neutral temperature and optimum......, temperature drift: first 4 h: +2 K/h, last 4 h: –2 K/h. The results indicate that thermal sensation of the elderly was, in general, 0.5 scale units lower in comparison with their younger counterparts. Furthermore, the elderly showed more distal vasoconstriction during both conditions. Nevertheless, TS...

  9. Thermal contact resistance in carbon nanotube enhanced heat storage materials

    NARCIS (Netherlands)

    Zhang, H.; Nedea, S.V.; Rindt, C.C.M.; Smeulders, D.M.J.

    2015-01-01

    Solid-liquid phase change is one of the most favorable means of compact and economical heat storage in the built environment. In such storage systems, the vast available solar heat is stored as latent heat in the storage materials. Recent studies suggest using sugar alcohols as seasonal heat storage

  10. Thermal and Electrical Properties of Nanocomposites, Including Material Properties

    NARCIS (Netherlands)

    Kochetov, R.

    2012-01-01

    The research described in this thesis is part of a state-funded IOP-EMVT project in cooperation with industrial companies, aiming at the design, assessment and implementation of new, environmental friendly (e.g. oil and SF6 - free) solid dielectric materials. A large disadvantage of solid polymer

  11. Thermal analysis of the APT materials irradiation samples

    International Nuclear Information System (INIS)

    Maloy, S.A.; Willcutt, G.J.; James, M.R.; Teague, J.; Diebe, D.A.; Sommer, W.F.; Ferguson, P.D.

    1998-01-01

    The accelerator production of tritium (APT) project proposes to use a 1.7 GeV, 100 mA proton beam to produce neutrons from an Inconel 718 clad tungsten target. The neutrons are multiplied and moderated in a lead/water blanket before being captured in He 3 to form tritium. In this process, the materials in the target and blanket region are exposed to a wide range of different fluxes comprised of protons and neutrons with energies into the GeV range. To investigate the effect of irradiation on the mechanical properties of candidate APT materials (Inconel 718, 316L stainless steel, Al 6061-T6, Mod 9Cr-1Mo, 304L stainless steel and Al5052-0), the APT Engineering Design and Development group fielded an extensive materials irradiation using the LANSCE (Los Alamos Neutron Science Center) accelerator, which operates at an energy of 800 MeV and a current of 1 mA. The test set-up was designed to place mechanical test specimens in locations in and near the proton beam where the environment of proton and neutron fluxes and temperatures are prototypic to those expected in the APT target/blanket (50--170 C). After irradiating for about 3,600 hours, the maximum achieved proton fluence was 4--5 x 10 21 p/cm 2 for the materials in the center of the beam. To obtain relevant data on the change in the mechanical properties with fluence, it is essential to know the temperature at which the materials were irradiated. This paper explains the method of determining the specimen temperature and reports some specific examples

  12. Effect of Material Composition and Environmental Condition on Thermal Characteristics of Conductive Asphalt Concrete

    Directory of Open Access Journals (Sweden)

    Pan Pan

    2017-02-01

    Full Text Available Conductive asphalt concrete with high thermal conductivity has been proposed to improve the solar energy collection and snow melting efficiencies of asphalt solar collector (ASC. This paper aims to provide some insight into choosing the basic materials for preparation of conductive asphalt concrete, as well as determining the evolution of thermal characteristics affected by environmental factors. The thermal properties of conductive asphalt concrete were studied by the Thermal Constants Analyzer. Experimental results showed that aggregate and conductive filler have a significant effect on the thermal properties of asphalt concrete, while the effect of asphalt binder was not evident due to its low proportion. Utilization of mineral aggregate and conductive filler with higher thermal conductivity is an efficient method to prepare conductive asphalt concrete. Moreover, change in thermal properties of asphalt concrete under different temperature and moisture conditions should be taken into account to determine the actual thermal properties of asphalt concrete. There was no noticeable difference in thermal properties of asphalt concrete before and after aging. Furthermore, freezing–thawing cycles strongly affect the thermal properties of conductive asphalt concrete, due to volume expansion and bonding degradation.

  13. Two-phase flow and thermal response from nuclear excursions in tuff

    International Nuclear Information System (INIS)

    Rath, J.S.; Sanchez, L.C.; Taylor, L.L.

    1998-05-01

    Thermal hydrology calculations were performed to predict the geologic thermal and saturation response of a far-field nuclear criticality. The thermal hydrology (THX) calculations used an experimental version of a transient multi-phase fluid and energy simulator, BRAGFLO T. A total of 45 THX calculations were completed using various combinations of initial saturation S 0 , input heat generation zone (HGZ) radii r 0 , input energies E 0 , and input space power density functions (SPDFs). The thermal hydrology calculations were performed as a part the nuclear dynamics consequence analysis (NDCA) study for potential criticality consequences associated with disposal of high-level waste (HLW) and spent nuclear fuel (SNF) in an underground geologic repository. In the NDCA study it was identified that total fission energy E 0 , integrated from the power-time history, has an expected range of 10 17 --10 20 total fissions per excursion. This range of values is comparable to those reported for aqueous criticality accidents that had occurred in processing plants. The THX results show (using the conservative temperature recycle times) that a criticality frequency between 3 and 30 criticalities/yr is possible. Probability frequencies (generated by probabilistic risk analysis and the THX model) for these consequences indicate that any additional fissions are minor contributions to the biological hazards caused by the disposed fissile materials

  14. The CLYC-6 and CLYC-7 response to γ-rays, fast and thermal neutrons

    International Nuclear Information System (INIS)

    Giaz, A.; Pellegri, L.; Camera, F.; Blasi, N.; Brambilla, S.; Ceruti, S.; Million, B.; Riboldi, S.; Cazzaniga, C.; Gorini, G.; Nocente, M.; Pietropaolo, A.; Pillon, M.; Rebai, M.; Tardocchi, M.

    2016-01-01

    The crystal Cs 2 LiYCl 6 :Ce (CLYC) is a very interesting scintillator material because of its good energy resolution and its capability to identify γ-rays and fast/thermal neutrons. The crystal Cs 2 LiYCl 6 :Ce contains 6 Li and 35 Cl isotopes, therefore, it is possible to detect thermal neutrons through the reaction 6 Li(n, α)t while 35 Cl ions allow to measure fast neutrons through the reactions 35 Cl(n, p) 35 S and 35 Cl(n, α) 32 P. In this work two CLYC 1″×1″ crystals were used: the first crystal, enriched with 6 Li at 95% (CLYC-6) is ideal for thermal neutron measurements while the second one, enriched with 7 Li at >99% (CLYC-7) is suitable for fast neutron measurements. The response of CLYC scintillators was measured with different PMT models: timing or spectroscopic, with borosilicate glass or quartz window. The energy resolution, the neutron-γ discrimination and the internal activity are discussed. The capability of CLYC scintillators to discriminate γ rays from neutrons was tested with both thermal and fast neutrons. The thermal neutrons were measured with both detectors, using an AmBe source. The measurements of fast neutrons were performed at the Frascati Neutron Generator facility (Italy) where a deuterium beam was accelerated on a deuterium or on a tritium target, providing neutrons of 2.5 MeV or 14.1 MeV, respectively. The different sensitivity to thermal and fast neutrons of a CLYC-6 and of a CLYC-7 was additionally studied.

  15. Materials and society -- Impacts and responsibilities

    Energy Technology Data Exchange (ETDEWEB)

    Westwood, A.R.C.

    1995-11-01

    The needs of today`s advanced societies have moved well beyond the requirements for food and shelter, etc., and now are focused on such concerns as international peace and domestic security, affordable health care, the swift and secure transmission of information, the conservation of resources, and a clean environment. Progress in materials science and engineering is impacting each of these concerns. This paper will present some examples of how this is occurring, and then comment on ethical dilemmas that can arise as a consequence of technological advances. The need for engineers to participate more fully in the development of public policies that help resolve such dilemmas, and so promote the benefits of advancing technology to society, will be discussed.

  16. Tributaries affect the thermal response of lakes to climate change

    Science.gov (United States)

    Råman Vinnå, Love; Wüest, Alfred; Zappa, Massimiliano; Fink, Gabriel; Bouffard, Damien

    2018-01-01

    Thermal responses of inland waters to climate change varies on global and regional scales. The extent of warming is determined by system-specific characteristics such as fluvial input. Here we examine the impact of ongoing climate change on two alpine tributaries, the Aare River and the Rhône River, and their respective downstream peri-alpine lakes: Lake Biel and Lake Geneva. We propagate regional atmospheric temperature effects into river discharge projections. These, together with anthropogenic heat sources, are in turn incorporated into simple and efficient deterministic models that predict future water temperatures, river-borne suspended sediment concentration (SSC), lake stratification and river intrusion depth/volume in the lakes. Climate-induced shifts in river discharge regimes, including seasonal flow variations, act as positive and negative feedbacks in influencing river water temperature and SSC. Differences in temperature and heating regimes between rivers and lakes in turn result in large seasonal shifts in warming of downstream lakes. The extent of this repressive effect on warming is controlled by the lakes hydraulic residence time. Previous studies suggest that climate change will diminish deep-water oxygen renewal in lakes. We find that climate-related seasonal variations in river temperatures and SSC shift deep penetrating river intrusions from summer towards winter. Thus potentially counteracting the otherwise negative effects associated with climate change on deep-water oxygen content. Our findings provide a template for evaluating the response of similar hydrologic systems to on-going climate change.

  17. Tributaries affect the thermal response of lakes to climate change

    Directory of Open Access Journals (Sweden)

    L. Råman Vinnå

    2018-01-01

    Full Text Available Thermal responses of inland waters to climate change varies on global and regional scales. The extent of warming is determined by system-specific characteristics such as fluvial input. Here we examine the impact of ongoing climate change on two alpine tributaries, the Aare River and the Rhône River, and their respective downstream peri-alpine lakes: Lake Biel and Lake Geneva. We propagate regional atmospheric temperature effects into river discharge projections. These, together with anthropogenic heat sources, are in turn incorporated into simple and efficient deterministic models that predict future water temperatures, river-borne suspended sediment concentration (SSC, lake stratification and river intrusion depth/volume in the lakes. Climate-induced shifts in river discharge regimes, including seasonal flow variations, act as positive and negative feedbacks in influencing river water temperature and SSC. Differences in temperature and heating regimes between rivers and lakes in turn result in large seasonal shifts in warming of downstream lakes. The extent of this repressive effect on warming is controlled by the lakes hydraulic residence time. Previous studies suggest that climate change will diminish deep-water oxygen renewal in lakes. We find that climate-related seasonal variations in river temperatures and SSC shift deep penetrating river intrusions from summer towards winter. Thus potentially counteracting the otherwise negative effects associated with climate change on deep-water oxygen content. Our findings provide a template for evaluating the response of similar hydrologic systems to on-going climate change.

  18. Growth and development rates have different thermal responses.

    Science.gov (United States)

    Forster, Jack; Hirst, Andrew G; Woodward, Guy

    2011-11-01

    Growth and development rates are fundamental to all living organisms. In a warming world, it is important to determine how these rates will respond to increasing temperatures. It is often assumed that the thermal responses of physiological rates are coupled to metabolic rate and thus have the same temperature dependence. However, the existence of the temperature-size rule suggests that intraspecific growth and development are decoupled. Decoupling of these rates would have important consequences for individual species and ecosystems, yet this has not been tested systematically across a range of species. We conducted an analysis on growth and development rate data compiled from the literature for a well-studied group, marine pelagic copepods, and use an information-theoretic approach to test which equations best describe these rates. Growth and development rates were best characterized by models with significantly different parameters: development has stronger temperature dependence than does growth across all life stages. As such, it is incorrect to assume that these rates have the same temperature dependence. We used the best-fit models for these rates to predict changes in organism mass in response to temperature. These predictions follow a concave relationship, which complicates attempts to model the impacts of increasing global temperatures on species body size.

  19. Design of materials with extreme thermal expansion using a three-phase topology optimization method

    DEFF Research Database (Denmark)

    Sigmund, Ole; Torquato, S.

    1997-01-01

    We show how composites with extremal or unusual thermal expansion coefficients can be designed using a numerical topology optimization method. The composites are composed of two different material phases and void. The optimization method is illustrated by designing materials having maximum therma...

  20. Evaluation of thermal energy storage materials for advanced compressed air energy storage systems

    Energy Technology Data Exchange (ETDEWEB)

    Zaloudek, F.R.; Wheeler, K.R.; Marksberry, L.

    1983-03-01

    Advanced Compressed-Air Energy Storage (ACAS) plants have the near-term potential to reduce the fuel consumption of compressed-air plants from 33 to 100%, depending upon their design. Fuel is saved by storing some or all of the heat of compression as sensible heat which is subsequently used to reheat the compressed air prior to expansion in the turbine generator. The thermal storage media required for this application must be low cost and durable. The objective of this project was to screen thermal store materials based on their thermal cycle durability, particulate formation and corrosion resistant characteristics. The materials investigated were iron oxide pellets, Denstone pebbles, cast-iron balls, and Dresser basalt rock. The study specifically addressed the problems of particle formation and thermal ratcheting of the materials during thermal cycling and the chemical attack on the materials by the high temperature and moist environment in an ACAS heat storage bed. The results indicate that from the durability standpoint Denstone, cast iron containing 27% or more chromium, and crushed Dresser basalt would possibly stand up to ACAS conditions. If costs are considered in addition to durability and performance, the crushed Dresser basalt would probably be the most desirable heat storage material for adiabatic and hybrid ACAS plants, and more in-depth longer term thermal cycling and materials testing of Dresser basalt is recommended. Also recommended is the redesign and costing analysis of both the hybrid and adiabatic ACAS facilities based upon the use of Dresser basalt as the thermal store material.

  1. Thermal modelling of extrusion based additive manufacturing of composite materials

    DEFF Research Database (Denmark)

    Jensen, Mathias Laustsen; Sonne, Mads Rostgaard; Hattel, Jesper Henri

    One of the hottest topics regarding manufacturing these years is additive manufacturing (AM). AM is a young branch of manufacturing techniques, which by nature is disruptive due to its completely different manufacturing approach, wherein material is added instead of removed. By adding material...... layer by layer, mould and customised tooling requirements from the conventional manufacturing are reduced or removed, which leads to increased customisation options and enables new part complexities without increasing the manufacturing cost. AM hence enables customised small volume productions...... of composite parts not feasible by conventional manufacturing techniques. This sets up new requirements to the part verification and validation, while conventional destructive tests become too expensive. This initial study aims to investigate alternative options to this destructive testing by increasing...

  2. Thermal and microstructural properties of fine-grained material at the Viking Lander 1 site

    Science.gov (United States)

    Paton, M. D.; Harri, A.-M.; Savijärvi, H.; Mäkinen, T.; Hagermann, A.; Kemppinen, O.; Johnston, A.

    2016-06-01

    As Viking Lander 1 touched down on Mars one of its footpads fully penetrated a patch of loose fine-grained drift material. The surrounding landing site, as observed by VL-1, was found to exhibit a complex terrain consisting of a crusted surface with an assortment of rocks, large dune-like drifts and smaller patches of drift material. We use a temperature sensor attached to the buried footpad and covered in fine-grained material to determine the thermal properties of drift material at the VL-1 site. The thermal properties are used to investigate the microstructure of the drift material and understand its relevance to surface-atmosphere interactions. We obtained a thermal inertia value of 103 ± 22 tiu. This value is in the upper range of previous thermal inertia estimates of martian dust as measured from orbit and is significantly lower than the regional thermal inertia of the VL-1 site, of around 283 tiu, obtained from orbit. We estimate a thermal inertia of around 263 ± 29 tiu for the duricrust at the VL-1 site. It was noted the patch of fine-grained regolith around the footpad was about 20-30 K warmer compared to similar material beyond the thermal influence of the lander. An effective diameter of 8 ± 5 μm was calculated for the particles in the drift material. This is larger than atmospheric dust and large compared to previous estimates of the drift material particle diameter. We interpret our results as the presence of a range of particle sizes, <8 μm, in the drift material with the thermal properties being controlled by a small amount of large particles (∼8 μm) and its cohesion being controlled by a large amount of smaller particles. The bulk of the particles in the drift material are therefore likely comparable in size to that of atmospheric dust. The possibility of larger particles being locked into a fine-grained material has implications for understanding the mobilisation of wind blown materials on Mars.

  3. Damage of first wall materials in fusion reactors under nonstationary thermal effects

    International Nuclear Information System (INIS)

    Maslaev, S.A.; Platonov, Yu.M.; Pimenov, V.N.

    1991-01-01

    The temperature distribution in the first wall of a fusion reactor was calculated for nonstationary thermal effects of the type of plasma destruction or the flow of 'running electrons' taking into account the melting of the surface layer of the material. The thickness of the resultant damaged layer in which thermal stresses were higher than the tensile strength of the material is estimated. The results were obtained for corrosion-resisting steel, aluminium and vanadium. Flowing down of the molten layer of the material of the first wall is calculated. (author)

  4. The JPL Cryogenic Dilatometer: Measuring the Thermal Expansion Coefficient of Aerospace Materials

    Science.gov (United States)

    Halverson, Peter G.; Dudick, Matthew J.; Karlmann, Paul; Klein, Kerry J.; Levine, Marie; Marcin, Martin; Parker, Tyler J.; Peters, Robert D.; Shaklan, Stuart; VanBuren, David

    2007-01-01

    This slide presentation details the cryogenic dilatometer, which is used by JPL to measure the thermal expansion coefficient of materials used in Aerospace. Included is a system diagram, a picture of the dilatometer chamber and the laser source, a description of the laser source, pictures of the interferometer, block diagrams of the electronics and software and a picture of the electronics, and software. Also there is a brief review of the accurace.error budget. The materials tested are also described, and the results are shown in strain curves, JPL measured strain fits are described, and the coefficient of thermal expansion (CTE) is also shown for the materials tested.

  5. Mechanical and thermal stability of graphene and graphene-based materials

    Science.gov (United States)

    Galashev, A. E.; Rakhmanova, O. R.

    2014-10-01

    Graphene has rapidly become one of the most popular materials for technological applications and a test material for new condensed matter ideas. This paper reviews the mechanical properties of graphene and effects related to them that have recently been discovered experimentally or predicted theoretically or by simulation. The topics discussed are of key importance for graphene's use in integrated electronics, thermal materials, and electromechanical devices and include the following: graphene transformation into other sp^2 hybridization forms; stability to stretching and compression; ion-beam-induced structural modifications; how defects and graphene edges affect the electronic properties and thermal stability of graphene and related composites.

  6. NECAP 4.1: NASA's Energy Cost Analysis Program thermal response factor routine

    Science.gov (United States)

    Weise, M. R.

    1982-08-01

    A thermal response factor is described and calculation sequences and flowcharts for RESFAC2 are provided. RESFAC is used by NASA's (NECAP) to calculate hourly heat transfer coefficients (thermal response factors) for each unique delayed surface. NECAP uses these response factors to compute each spaces' hourly heat gain/loss.

  7. Thickness optimization of various moderator materials for maximization of thermal neutron fluence

    International Nuclear Information System (INIS)

    Dhang, Prosenjit; Verma, Rishi; Shyam, Anurag

    2015-01-01

    Plasma focus device is widely being used as pulsed neutron source for variety of applications. Measurements of neutron yield by largely preferred Helium-3 proportional counter and Silver activation counter are mainly sensitive to thermal neutrons and are typically used with a neutron moderator. Thermalization of neutron is based on scattering reaction and hydrogenous materials are the best thermalizing medium. The efficiency of aforementioned neutron detectors is considerably affected by physical and geometrical properties of thermalizing medium i.e. moderator material, its thickness and shape. In view of the same, simulations have been performed to explore the effective utilization of Polyethylene, Perspex and Light water as moderating mediums for cylindrical and spherical geometry. In this study, estimated thermal fluence value up to 0.5 eV has been considered as the benchmark factor for comparing efficient thermalization by specific material, its thickness and shape. In either of the shapes being cylindrical or spherical, use of Polyethylene as moderating medium has resulted in minimum optimum thickness along with highest thermal fluence. (author)

  8. 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)

  9. Solid state phase change materials for thermal energy storage in passive solar heated buildings

    Science.gov (United States)

    Benson, D. K.; Christensen, C.

    1983-11-01

    A set of solid state phase change materials was evaluated for possible use in passive solar thermal energy storage systems. The most promising materials are organic solid solutions of pentaerythritol, pentaglycerine and neopentyl glycol. Solid solution mixtures of these compounds can be tailored so that they exhibit solid-to-solid phase transformations at any desired temperature within the range from less than 25 deg to 188 deg. Thermophysical properties such as thermal conductivity, density and volumetric expansion were measured. Computer simulations were used to predict the performance of various Trombe wall designs incorporating solid state phase change materials. Optimum performance was found to be sensitive to the choice of phase change temperatures and to the thermal conductivity of the phase change material. A molecular mechanism of the solid state phase transition is proposed and supported by infrared spectroscopic evidence.

  10. Preparation and thermal properties of form stable paraffin phase change material encapsulation

    International Nuclear Information System (INIS)

    Liu Xing; Liu Hongyan; Wang Shujun; Zhang Lu; Cheng Hua

    2006-01-01

    Paraffin waxes are cheap and have moderate thermal energy storage density but low thermal conductivity and, hence, require large surface area to be used in energy storage. Form stable paraffin phase change materials (PCM) in which paraffin serves as a latent heat storage material and polyolefins act as a supporting material, because of paraffin leakage, are required to be improved. The form stable paraffin PCM in the present paper was encapsulated in an inorganic silica gel polymer successfully by in situ polymerization. The differential scanning calorimeter (DSC) was used to measure its thermal properties. At the same time, the Washburn equation, which measures the wetting properties of powder materials, was used to test the hydrophilic-lipophilic properties of the PCMs. The result indicated that the enthalpy of the microencapsulated PCMs was reduced little, while their hydrophilic properties were enhanced largely

  11. Thermal engineering of FAPbI3 perovskite material via radiative thermal annealing and in situ XRD

    Science.gov (United States)

    Pool, Vanessa L.; Dou, Benjia; Van Campen, Douglas G.; Klein-Stockert, Talysa R.; Barnes, Frank S.; Shaheen, Sean E.; Ahmad, Md I.; van Hest, Maikel F. A. M.; Toney, Michael F.

    2017-01-01

    Lead halide perovskites have emerged as successful optoelectronic materials with high photovoltaic power conversion efficiencies and low material cost. However, substantial challenges remain in the scalability, stability and fundamental understanding of the materials. Here we present the application of radiative thermal annealing, an easily scalable processing method for synthesizing formamidinium lead iodide (FAPbI3) perovskite solar absorbers. Devices fabricated from films formed via radiative thermal annealing have equivalent efficiencies to those annealed using a conventional hotplate. By coupling results from in situ X-ray diffraction using a radiative thermal annealing system with device performances, we mapped the processing phase space of FAPbI3 and corresponding device efficiencies. Our map of processing-structure-performance space suggests the commonly used FAPbI3 annealing time, 10 min at 170 °C, can be significantly reduced to 40 s at 170 °C without affecting the photovoltaic performance. The Johnson-Mehl-Avrami model was used to determine the activation energy for decomposition of FAPbI3 into PbI2. PMID:28094249

  12. Preparation and characterization of stearic acid/expanded graphite composites as thermal energy storage materials

    International Nuclear Information System (INIS)

    Fang, Guiyin; Li, Hui; Chen, Zhi; Liu, Xu

    2010-01-01

    Stearic acid/expanded graphite composites with different mass ratios were prepared by absorbing liquid stearic acid into the expanded graphite. In the composite materials, the stearic acid was used as the phase change material for thermal energy storage, and the expanded graphite acted as the supporting material. Fourier transformation infrared spectroscopy, X-ray diffraction, scanning electron microscopy and thermal diffusivity measurement were used to determine the chemical structure, crystalline phase, microstructure and thermal diffusivity of the composites, respectively. The thermal properties and thermal stability were investigated by differential scanning calorimetry and thermogravimetric analysis. The thermal analysis results indicated that the materials exhibited the same phase transition characteristics as the stearic acid and their latent heats were approximately the same as the values calculated based on the weight fraction of the stearic acid in the composites. The microstructural analysis results showed that the stearic acid was well absorbed in the porous network of the expanded graphite, and there was no leakage of the stearic acid from the composites even when it was in the molten state.

  13. Thermal performance of a phase change material on a nickel-plated surface

    International Nuclear Information System (INIS)

    Nurmawati, M.H.; Siow, K.S.; Rasiah, I.J.

    2004-01-01

    Thermal control becomes increasingly vital with IC chips becoming faster and smaller. The need to keep chips within acceptable operating temperatures is a growing challenge. Thermal interface materials (TIM) form the interfaces that improve heat transfer from the heat-generating chip to the heat dissipating thermal solution. One of the most commonly used materials in today's electronics industry is phase change material (PCM). Typically, the heat spreader is a nickel-plated copper surface. The compatibility of the PCM to this surface is crucial to the performance of the TIM. In this paper, we report on the performance of this interface. To that end, an instrument to suitably measure critical parameters, like the apparent and contact thermal resistance of the TIM, is developed according to the ASTM D5470 and calibrated. A brief theory of TIM is described and the properties of the PCM were investigated using the instrument. Thermal resistance measurements were made to investigate the effects of physical parameters like pressure, temperature and supplied power on the thermal performance of the material on nickel-plated surface. Conclusions were drawn on the effectiveness of the interface and their application in IC packages

  14. Concurrent design of composite materials and structures considering thermal conductivity constraints

    Science.gov (United States)

    Jia, J.; Cheng, W.; Long, K.

    2017-08-01

    This article introduces thermal conductivity constraints into concurrent design. The influence of thermal conductivity on macrostructure and orthotropic composite material is extensively investigated using the minimum mean compliance as the objective function. To simultaneously control the amounts of different phase materials, a given mass fraction is applied in the optimization algorithm. Two phase materials are assumed to compete with each other to be distributed during the process of maximizing stiffness and thermal conductivity when the mass fraction constraint is small, where phase 1 has superior stiffness and thermal conductivity whereas phase 2 has a superior ratio of stiffness to density. The effective properties of the material microstructure are computed by a numerical homogenization technique, in which the effective elasticity matrix is applied to macrostructural analyses and the effective thermal conductivity matrix is applied to the thermal conductivity constraint. To validate the effectiveness of the proposed optimization algorithm, several three-dimensional illustrative examples are provided and the features under different boundary conditions are analysed.

  15. Investigation of thermal and temporal responses of ionization chambers in radiation dosimetry.

    Science.gov (United States)

    AlMasri, Hussein; Funyu, Akira; Kakinohana, Yasumasa; Murayama, Sadayuki

    2012-07-01

    The ionization chamber is a primary dosimeter that is used in radiation dosimetry. Generally, the ion chamber response requires temperature/pressure correction according to the ideal gas law. However, this correction does not consider the thermal volume effect of chambers. The temporal and thermal volume effects of various chambers (CC01, CC13, NACP parallel-plate, PTW) with different wall and electrode materials have been studied in a water phantom. Measurements were done after heating the water with a suitable heating system, and chambers were submerged for a sufficient time to allow for temperature equilibrium. Temporal results show that all chambers equilibrate quickly in water. The equilibration time was between 3 and 5 min for all chambers. Thermal results show that all chambers expanded in response to heating except for the PTW, which contracted. This might be explained by the differences in the volumes of all chambers and also by the difference in wall material composition of PTW from the other chambers. It was found that the smallest chamber, CC01, showed the greatest expansion. The magnitude of the expansion was ~1, 0.8, and 0.9% for CC01, CC13, and parallel-plate chambers, respectively, in the temperature range of 295-320 K. The magnitude of the detected contraction was <0.3% for PTW in the same temperature range. For absolute dosimetry, it is necessary to make corrections for the ion chamber response, especially for small ion chambers like the CC01. Otherwise, room and water phantom temperatures should remain within a close range.

  16. The development and characterization of stimuli-responsive systems for performance materials

    Science.gov (United States)

    Gordon, Melissa B.

    shown including: (1) photo-induced healing and strengthening of a specimen after it has been severed, (2) photopatterning for effecting spatially confined property changes on demand, and (3) locking in the film's 3D geometry using light after reshaping. The utility of the photo-responsive dynamic bond is enhanced by demonstrating that it is also responsive to mechanical force. Force-responsive materials are activated by the energy from the damage event itself, thereby enabling healing without human intervention. Specifically, selective cleavage of a polymer containing a dynamic trithiocarbonate group initiates a force-driven radical polymerization, thus enabling the material to constructively respond to force via gelation on an experimentally relevant timescale. To enhance the stress response of the self-healing materials described above, a protective material composed of colloidal particles is proposed. Toward this goal, the second half of this dissertation investigates the microstructural basis of rheological aging in colloidal gels and glasses using a model thermoreversible colloidal dispersion. In this work, rheological aging is quantitatively related to microstructural aging in glasses and gels by simultaneously measuring the bulk properties and sample microstructure using rheometry and small angle neutron scattering (Rheo-SANS), respectively. A one-to-one correspondence between the evolution in storage modulus and microstructure as the sample ages is observed, which is investigated as a function of thermal and shear history. The microstructural measurements are consistent with the hypothesis of aging as a trajectory in a free energy landscape, which combined with analysis with mode coupling theory, support local particle rearrangements as the mechanism of aging. Moreover, by using a system that is fully rejuvenated by thermal cycling, the effectiveness of shear as a rejuvenation method is investigated by directly comparing microstructure and bulk properties

  17. A Study on the Thermal Neutron Filter for the Irradiation of Electronic Materials at HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Seong Woo; Kim, Sung Ryul; Park, Seung Jae; Shin, Yoon Taeg; Cho, Man Soon; Cho, Kee Nam [KAERI, Daejeon (Korea, Republic of)

    2016-05-15

    The representative example is a technique of making the semiconductor with the transmutation using the pure Si. This NTD (Neutron Transmutation Doping) Si is used as a high-quality semiconductor because it has a uniform resistance. Likewise, the electronic materials are being investigated to improve the performance of material using the neutron irradiation method. The mechanism for reaction between the electronic materials and the neutrons depends on the energy of the neutron. Capturing reaction by thermal neutrons causes the transmutation and a lot of defects are made by fast neutrons. The study for the effect by such neutron energy is necessary to understand the performance improvement of the irradiated electronic materials. The thermal neutron filter was investigated to be used for the irradiation of electronic materials at HANARO. IP irradiation hole was selected and the irradiation device was designed. The analysis was conducted considering four candidate materials.

  18. Shock-induced thermal wave propagation and response analysis of a viscoelastic thin plate under transient heating loads

    Science.gov (United States)

    Li, Chenlin; Guo, Huili; Tian, Xiaogeng

    2018-04-01

    This paper is devoted to the thermal shock analysis for viscoelastic materials under transient heating loads. The governing coupled equations with time-delay parameter and nonlocal scale parameter are derived based on the generalized thermo-viscoelasticity theory. The problem of a thin plate composed of viscoelastic material, subjected to a sudden temperature rise at the boundary plane, is solved by employing Laplace transformation techniques. The transient responses, i.e. temperature, displacement, stresses, heat flux as well as strain, are obtained and discussed. The effects of time-delay and nonlocal scale parameter on the transient responses are analyzed and discussed. It can be observed that: the propagation of thermal wave is dynamically smoothed and changed with the variation of time-delay; while the displacement, strain, and stress can be rapidly reduced by nonlocal scale parameter, which can be viewed as an important indicator for predicting the stiffness softening behavior for viscoelastic materials.

  19. Design and construction of thermal desorption measurement system for tritium contained materials

    International Nuclear Information System (INIS)

    Hara, M.; Hatano, Y.; Calderoni, P.; Shimada, M.

    2014-01-01

    The dual-mode thermal desorption analysis system was designed and built in Idaho National Laboratory (INL) to examine the evolution of the hydrogen isotope gas from materials. The system is equipped with a mass spectrometer for stable hydrogen isotopes and an ionization chamber for tritium components. The performance of the system built was tested with using tritium contained materials. The evolution of tritiated gas species from contaminated materials was measured successfully by using the system. (author)

  20. Materials compatibility issues related to thermal energy storage for a space solar dynamic power system

    Science.gov (United States)

    Faget, N. M.

    1986-01-01

    Attention is given to results obtained to date in developmental investigations of a thermal energy storage (TES) system for the projected NASA Space Station's solar dynamic power system; these tests have concentrated on issues related to materials compatibility for phase change materials (PCMs) and their containment vessels' materials. The five PCMs tested have melting temperatures that correspond to the operating temperatures of either the Brayton or Rankine heat engines, which were independently chosen for their high energy densities.

  1. Programmable thermal emissivity structures based on bioinspired self-shape materials

    Science.gov (United States)

    Athanasopoulos, N.; Siakavellas, N. J.

    2015-12-01

    Programmable thermal emissivity structures based on the bioinspired self-shape anisotropic materials were developed at macro-scale, and further studied theoretically at smaller scale. We study a novel concept, incorporating materials that are capable of transforming their shape via microstructural rearrangements under temperature stimuli, while avoiding the use of exotic shape memory materials or complex micro-mechanisms. Thus, programmed thermal emissivity behaviour of a surface is achievable. The self-shape structure reacts according to the temperature of the surrounding environment or the radiative heat flux. A surface which incorporates self-shape structures can be designed to quickly absorb radiative heat energy at low temperature levels, but is simultaneously capable of passively controlling its maximum temperature in order to prevent overheating. It resembles a “game” of colours, where two or more materials coexist with different values of thermal emissivity/ absorptivity/ reflectivity. The transformation of the structure conceals or reveals one of the materials, creating a surface with programmable - and therefore, variable- effective thermal emissivity. Variable thermal emissivity surfaces may be developed with a total hemispherical emissivity ratio (ɛEff_H/ɛEff_L) equal to 28.

  2. Spatially distributed damage detection in CMC thermal protection materials using thin-film piezoelectric sensors

    Science.gov (United States)

    Kuhr, Samuel J.; Blackshire, James L.; Na, Jeong K.

    2009-03-01

    Thermal protection systems (TPS) of aerospace vehicles are subjected to impacts during in-flight use and vehicle refurbishment. The damage resulting from such impacts can produce localized regions that are unable to resist extreme temperatures. Therefore it is essential to have a reliable method to detect, locate, and quantify the damage occurring from such impacts. The objective of this research is to demonstrate a capability that could lead to detecting, locating and quantifying impact events for ceramic matrix composite (CMC) wrapped tile TPS via sensors embedded in the TPS material. Previous research had shown a correlation between impact energies, material damage state, and polyvinylidene fluoride (PVDF) sensor response for impact energies between 0.07 - 1.00 Joules, where impact events were located directly over the sensor positions1. In this effort, the effectiveness of a sensor array is evaluated for detecting and locating low energy impacts on a CMC wrapped TPS. The sensor array, which is adhered to the internal surface of the TPS tile, is used to detect low energy impact events that occur at different locations. The analysis includes an evaluation of signal amplitude levels, time-of-flight measurements, and signal frequency content. Multiple impacts are performed at each location to study the repeatability of each measurement.

  3. Multi-scale thermal stability of a hard thermoplastic protein-based material

    Science.gov (United States)

    Latza, Victoria; Guerette, Paul A.; Ding, Dawei; Amini, Shahrouz; Kumar, Akshita; Schmidt, Ingo; Keating, Steven; Oxman, Neri; Weaver, James C.; Fratzl, Peter; Miserez, Ali; Masic, Admir

    2015-09-01

    Although thermoplastic materials are mostly derived from petro-chemicals, it would be highly desirable, from a sustainability perspective, to produce them instead from renewable biopolymers. Unfortunately, biopolymers exhibiting thermoplastic behaviour and which preserve their mechanical properties post processing are essentially non-existent. The robust sucker ring teeth (SRT) from squid and cuttlefish are one notable exception of thermoplastic biopolymers. Here we describe thermoplastic processing of squid SRT via hot extrusion of fibres, demonstrating the potential suitability of these materials for large-scale thermal forming. Using high-resolution in situ X-ray diffraction and vibrational spectroscopy, we elucidate the molecular and nanoscale features responsible for this behaviour and show that SRT consist of semi-crystalline polymers, whereby heat-resistant, nanocrystalline β-sheets embedded within an amorphous matrix are organized into a hexagonally packed nanofibrillar lattice. This study provides key insights for the molecular design of biomimetic protein- and peptide-based thermoplastic structural biopolymers with potential biomedical and 3D printing applications.

  4. Phase-change materials: vibrational softening upon crystallization and its impact on thermal properties

    Energy Technology Data Exchange (ETDEWEB)

    Matsunaga, Toshiyuki [Materials Science and Analysis Technology Centre, Panasonic Corporation, Osaka (Japan); Japan Synchrotron Radiation Research Institute Hyogo (Japan); Yamada, Noboru [Digital and Network Technology Development Centre, Panasonic Corporation, Osaka (Japan); Japan Synchrotron Radiation Research Institute Hyogo (Japan); Kojima, Rie [Digital and Network Technology Development Centre, Panasonic Corporation, Osaka (Japan); Shamoto, Shinichi [Neutron Science Research Centre, Japan Atomic Energy Research Institute, Ibaraki (Japan); Sato, Masugu; Tanida, Hajime; Uruga, Tomoya; Kohara, Shinji [Japan Synchrotron Radiation Research Institute, Hyogo (Japan); Takata, Masaki [SPring-8/RIKEN, Hyogo, Japan, Department of Advanced Materials Science, School of Frontier Sciences, The University of Tokyo, Chiba (Japan); Zalden, Peter; Bruns, Gunnar; Wuttig, Matthias [I. Physikalisches Institut und JARA-FIT, RWTH Aachen Univ. (Germany); Sergueev, Ilya [European Synchrotron Radiation Facility, Grenoble (France); Wille, Hans Christian [Deutsches Elektronen-Synchrotron, Hamburg (Germany); Hermann, Raphael Pierre [Juelich Centre for Neutron Science JCNS and Peter Gruenberg, Institut PGI, JARA-FIT, Forschungszentrum Juelich GmbH (Germany); Faculte des Sciences, Universite de Liege (Belgium)

    2011-06-21

    Crystallization of an amorphous solid is usually accompanied by a significant change of transport properties, such as an increase in thermal and electrical conductivity. This fact underlines the importance of crystalline order for the transport of charge and heat. Phase-change materials, however, reveal a remarkably low thermal conductivity in the crystalline state. The small change in this conductivity upon crystallization points to unique lattice properties. The present investigation reveals that the thermal properties of the amorphous and crystalline state of phase-change materials show remarkable differences such as higher thermal displacements and a more pronounced anharmonic behavior in the crystalline phase. These findings are related to the change of bonding upon crystallization, which leads to an increase of the sound velocity and a softening of the optical phonon modes at the same time. (Copyright copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Replacement of Ablators with Phase-Change Material for Thermal Protection of STS Elements

    Science.gov (United States)

    Kaul, Raj K.; Stuckey, Irvin; Munafo, Paul M. (Technical Monitor)

    2002-01-01

    As part of the research and development program to develop new Thermal Protection System (TPS) materials for aerospace applications at NASA's Marshall Space Flight Center (MSFC), an experimental study was conducted on a new concept for a non-ablative TPS material. Potential loss of TPS material and ablation by-products from the External Tank (ET) or Solid Rocket Booster (SRB) during Shuttle flight with the related Orbiter tile damage necessitates development of a non-ablative thermal protection system. The new Thermal Management Coating (TMC) consists of phase-change material encapsulated in micro spheres and a two-part resin system to adhere the coating to the structure material. The TMC uses a phase-change material to dissipate the heat produced during supersonic flight rather than an ablative material. This new material absorbs energy as it goes through a phase change during the heating portion of the flight profile and then the energy is slowly released as the phase-change material cools and returns to its solid state inside the micro spheres. The coating was subjected to different test conditions simulating design flight environments at the NASA/MSFC Improved Hot Gas Facility (IHGF) to study its performance.

  6. A thermal lens response of the two components liquid in a thin Him cell

    International Nuclear Information System (INIS)

    Ivanov, V I; Ivanova, G D

    2016-01-01

    It was proposed a new thermal lens scheme with a thin layer of cell thickness which is significantly less than the size of the beam. As a result the exact analytical expression for the thermal lens response is achieved, taking into account the thermal lens in the windows of the cell. (paper)

  7. Nano-Material and Structural Engineering for Thermal Highways

    Science.gov (United States)

    2013-06-14

    Human body responds in a similar way in response to small increases in internal temperature above 37 °C, at which point cutaneous blood vessels in...curved liquid vapor interface with radius r. Upon initial wetting , the water in the pores forms a meniscus with radius of curvature on the order of...optimization, it should be noted that the PLD-Bi films showed very rough root-mean-square roughness of 1.57 nm (as-deposited) and 1.29 nm (post- annealed

  8. Thermal Protection Performance of Carbon Aerogels Filled with Magnesium Chloride Hexahydrate as a Phase Change Material

    Directory of Open Access Journals (Sweden)

    Ali Kazemi

    2014-02-01

    Full Text Available Carbon aerogels are comprised of a class of low density open-cell foams with large void space, nanometer pore size and composed of sparsely semi-colloidal nanometer sized particles forming an open porous structure. Phase change materials are those with high heat of fusion that could absorb and release a large amount of energy at the time of phase transition. These materials are mostly used as thermal energy storage materials but in addition they could serve as an obstacle for passage of heat during phase changes and this has led to their use in thermal protection systems. In this study, the effect of magnesium chloride hexahydrate, as a phase change material (melting point 115°C, on thermal properties of carbon aerogels is investigated. Thermal performance tests are designed and used for comparing the temperature-time behavior of the samples. DSC is applied to obtain the latent heat of melting of the phase change materials and the SEM tests are used to analyze the microstructure and morphology of carbon aerogels. The results show that the low percentage of phase change materials in carbon aerogels does not have any significant positive effect on carbon aerogels thermal properties. However, these properties are improved by increasing the percentage of phase change materials. With high percentage of phase change materials, a sample surface at 300°C would display an opposite surface with a significant drop in temperature increases, while at 115-200°C, with carbon aerogels, having no phase change materials, there is a severe reduction in the rate of temperature increase of the sample.

  9. Thermal and Chemical Characterization of Non-Metallic Materials Using Coupled Thermogravimetric Analysis and Infrared Spectroscopy

    Science.gov (United States)

    Huff, Timothy L.

    2002-01-01

    Thermogravimetric analysis (TGA) is widely employed in the thermal characterization of non-metallic materials, yielding valuable information on decomposition characteristics of a sample over a wide temperature range. However, a potential wealth of chemical information is lost during the process, with the evolving gases generated during thermal decomposition escaping through the exhaust line. Fourier Transform-Infrared spectroscopy (FT-IR) is a powerful analytical technique for determining many chemical constituents while in any material state, in this application, the gas phase. By linking these two techniques, evolving gases generated during the TGA process are directed into an appropriately equipped infrared spectrometer for chemical speciation. Consequently, both thermal decomposition and chemical characterization of a material may be obtained in a single sample run. In practice, a heated transfer line is employed to connect the two instruments while a purge gas stream directs the evolving gases into the FT-IR. The purge gas can be either high purity air or an inert gas such as nitrogen to allow oxidative and pyrolytic processes to be examined, respectively. The FT-IR data is collected realtime, allowing continuous monitoring of chemical compositional changes over the course of thermal decomposition. Using this coupled technique, an array of diverse materials has been examined, including composites, plastics, rubber, fiberglass epoxy resins, polycarbonates, silicones, lubricants and fluorocarbon materials. The benefit of combining these two methodologies is of particular importance in the aerospace community, where newly developing materials have little available data with which to refer. By providing both thermal and chemical data simultaneously, a more definitive and comprehensive characterization of the material is possible. Additionally, this procedure has been found to be a viable screening technique for certain materials, with the generated data useful in

  10. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-01-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued

  11. 3D Printing of Living Responsive Materials and Devices.

    Science.gov (United States)

    Liu, Xinyue; Yuk, Hyunwoo; Lin, Shaoting; Parada, German Alberto; Tang, Tzu-Chieh; Tham, Eléonore; de la Fuente-Nunez, Cesar; Lu, Timothy K; Zhao, Xuanhe

    2018-01-01

    3D printing has been intensively explored to fabricate customized structures of responsive materials including hydrogels, liquid-crystal elastomers, shape-memory polymers, and aqueous droplets. Herein, a new method and material system capable of 3D-printing hydrogel inks with programed bacterial cells as responsive components into large-scale (3 cm), high-resolution (30 μm) living materials, where the cells can communicate and process signals in a programmable manner, are reported. The design of 3D-printed living materials is guided by quantitative models that account for the responses of programed cells in printed microstructures of hydrogels. Novel living devices are further demonstrated, enabled by 3D printing of programed cells, including logic gates, spatiotemporally responsive patterning, and wearable devices. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  12. A study on the bonding residual thermal stress analysis of dissimilar materials using boundary element method

    International Nuclear Information System (INIS)

    Yi, Won; Yu, Yeong Chul; Jeong, Eui Seob; Lee, Chang Ho

    1995-01-01

    It is very important to evaluate the bonding residual thermal stress in dissimilar materials such as LSI package. In this study, the bonding residual thermal stress was calculated using the boundary element method, varing with the sub-element, geometry of specimen and adhesive thickness. The present results reveal a stress singularity at the edge of the interface, therefore the bonding strength of metal/resin interface can be estimated by taking into account it.

  13. A metric for characterizing the effectiveness of thermal mass in building materials

    International Nuclear Information System (INIS)

    Talyor, Robert A.; Miner, Mark

    2014-01-01

    Highlights: • Proposes a metric for interior thermal mass materials (floors, walls, counters). • Simple, yet effective, metric composed of easily calculated ‘local’ and ‘global’ variables. • Like Energy Star, the proposed metric gives a single number to aid consumer choice. • The metric is calculated and compared for selected, readily available data. • Drywall, concrete flooring, and wood paneling are quite effective thermal mass. - Abstract: Building energy use represents approximately 25% of the average total global energy consumption (for both residential and commercial buildings). Heating, ventilation, and air conditioning (HVAC) – in most climates – embodies the single largest draw inside our buildings. In many countries around the world a concerted effort is being made towards retrofitting existing buildings to improve energy efficiency. Better windows, insulation, and ducting can make drastic differences in the energy consumption of a building HVAC system. Even with these improvements, HVAC systems are still required to compensate for daily and seasonal temperature swings of the surrounding environment. Thermal mass inside the thermal envelope can help to alleviate these swings. While it is possible to add specialty thermal mass products to buildings for this purpose, commercial uptake of these products is low. Common building interior building materials (e.g. flooring, walls, countertops) are often overlooked as thermal mass products, but herein we propose and analyze non-dimensional metrics for the ‘benefit’ of selected commonly available products. It was found that location-specific variables (climate, electricity price, material price, insolation) can have more than an order of magnitude influence in the calculated metrics for the same building material. Overall, this paper provides guidance on the most significant contributors to indoor thermal mass, and presents a builder- and consumer-friendly metric to inform decisions about

  14. Performance of tungsten-based materials and components under ITER and DEMO relevant steady-state thermal loads

    Energy Technology Data Exchange (ETDEWEB)

    Ritz, Guillaume Henri

    2011-07-01

    In nuclear fusion devices the surfaces directly facing the plasma are irradiated with high energy fluxes. The most intense loads are deposited on the divertor located at the bottom of the plasma chamber, which has to withstand continuous heat loads with a power density of several MW . m{sup -2} as well as transient events. These are much shorter (in the millisecond and sub-millisecond regime) but deposit a higher power densities of a few GW . m{sup -2}. The search for materials that can survive to those severe loading conditions led to the choice of tungsten which possesses advantageous attributes such as a high melting point, high thermal conductivity, low thermal expansion and an acceptable activation rate. These properties made it an attractive and promising candidate as armor material for divertors of future fusion devices such as ITER and DEMO. For the DEMO divertor, conceptual studies on helium-cooled tungsten plasma-facing components were performed. The concept was realized and tested under DEMO specific cyclic thermal loads. The examination of the plasma-facing components by microstructural analyses before and after thermal loading enabled to determine the mechanisms for components failure. Among others, it clearly showed the impact of the tungsten grade and the thermal stress induced crack formation on the performance of the armor material and in general of the plasma-facing component under high heat loads. A tungsten qualification program was launched to study the behaviour of various tungsten grades, in particular the crack formation, under fusion relevant steady-state thermal loads. In total, seven commercially available materials from two industrial suppliers were investigated. As the material's thermal response is strongly related to its microstructure, this program comprised different material geometries and manufacturing technologies. It also included the utilization of an actively cooled specimen holder which has been designed to perform

  15. Performance of tungsten-based materials and components under ITER and DEMO relevant steady-state thermal loads

    International Nuclear Information System (INIS)

    Ritz, Guillaume Henri

    2011-01-01

    In nuclear fusion devices the surfaces directly facing the plasma are irradiated with high energy fluxes. The most intense loads are deposited on the divertor located at the bottom of the plasma chamber, which has to withstand continuous heat loads with a power density of several MW . m -2 as well as transient events. These are much shorter (in the millisecond and sub-millisecond regime) but deposit a higher power densities of a few GW . m -2 . The search for materials that can survive to those severe loading conditions led to the choice of tungsten which possesses advantageous attributes such as a high melting point, high thermal conductivity, low thermal expansion and an acceptable activation rate. These properties made it an attractive and promising candidate as armor material for divertors of future fusion devices such as ITER and DEMO. For the DEMO divertor, conceptual studies on helium-cooled tungsten plasma-facing components were performed. The concept was realized and tested under DEMO specific cyclic thermal loads. The examination of the plasma-facing components by microstructural analyses before and after thermal loading enabled to determine the mechanisms for components failure. Among others, it clearly showed the impact of the tungsten grade and the thermal stress induced crack formation on the performance of the armor material and in general of the plasma-facing component under high heat loads. A tungsten qualification program was launched to study the behaviour of various tungsten grades, in particular the crack formation, under fusion relevant steady-state thermal loads. In total, seven commercially available materials from two industrial suppliers were investigated. As the material's thermal response is strongly related to its microstructure, this program comprised different material geometries and manufacturing technologies. It also included the utilization of an actively cooled specimen holder which has been designed to perform sophisticated

  16. Response of thermal ions to electromagnetic ion cyclotron waves

    Science.gov (United States)

    Anderson, B. J.; Fuselier, S. A.

    1994-01-01

    Electromagnetic ion cyclotron waves generated by 10 - 50 keV protons in the Earth's equatorial magnetosphere will interact with the ambient low-energy ions also found in this region. We examine H(+) and He(+) distribution functions from approx. equals 1 to 160 eV using the Hot Plasma Composition Experiment instrument on AMPTE/CCE to investigate the thermal ion response to the waves. A total of 48 intervals were chosen on the basis of electromagnetic ion cyclotron (EMIC) wave activity: 24 with prevalent EMIC waves and 24 with no EMIC waves observed on the orbit. There is a close correlation between EMIC waves and perpendicular heated ion distributions. For protons the perpendicular temperature increase is modest, about 5 eV, and is always observed at 90 deg pitch angles. This is consistent with a nonresonant interaction near the equator. By contrast, He(+) temperatures during EMIC wave events averaged 35 eV and sometimes exceeded 100 eV, indicating stronger interaction with the waves. Furthermore, heated He(+) ions have X-type distributions with maximum fluxes occurring at pitch angles intermediate between field-aligned and perpendicular directions. The X-type He(+) distributions are consistent with a gyroresonant interaction off the equator. The concentration of He(+) relative to H(+) is found to correlate with EMIC wave activity, but it is suggested that the preferential heating of He(+) accounts for the apparent increase in relative He(+) concentration by increasing the proportion of He(+) detected by the ion instrument.

  17. ANALYSIS OF THERMAL PROPERTIES AND HEAT LOSS IN CONSTRUCTION AND ISOTHERMAL MATERIALS OF MULTILAYER BUILDING WALLS

    Directory of Open Access Journals (Sweden)

    Arkadiusz Urzędowski

    2017-06-01

    Full Text Available The article discusses the impact of vertical partition, technology on thermal insulation of the building, and the resulting savings and residents thermal comfort. The study is carried out as an analysis of three selected design solutions including such materials as: aerated concrete elements, polystyrene, ceramic elements, concrete, mineral plaster. Simulation results of heat transfer in a multi-layered wall, are subjected to detailed analysis by means of thermal visual methods. The study of existing structures, helped to identify the local point of heat loss by means of infrared technology leading to determination of U-value reduction by 36% in maximum for the described 3 types of structure.

  18. The thermal expansion of hard magnetic materials of the Nd-Fe-B system

    Science.gov (United States)

    Savchenko, Igor; Kozlovskii, Yurii; Samoshkin, Dmitriy; Yatsuk, Oleg

    2017-10-01

    The results of dilatometric measurement of the thermal expansion of hard magnetic materials brands N35M, N35H and N35SH containing as a main component the crystalline phase of Nd2Fe14B type are presented. The temperature range from 200 to 750 K has been investigated by the method of dilatometry with an error of 1.5-2×10-7 K-1. The approximation dependences of the linear thermal expansion coefficient have been obtained. The character of changes of the thermal coefficient of linear expansion in the region of the Curie point has been specified, its critical indices and critical amplitudes have been defined.

  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. Thermal-vacuum facility with in-situ mechanical loading. [for testing space construction materials

    Science.gov (United States)

    Tennyson, R. C.; Hansen, J. S.; Holzer, R. P.; Uffen, B.; Mabson, G.

    1978-01-01

    The paper describes a thermal-vacuum space simulator used to assess property changes of fiber-reinforced polymer composite systems. The facility can achieve a vacuum of approximately .0000001 torr with temperatures ranging from -200 to +300 F. Some preliminary experimental results are presented for materials subjected to thermal loading up to 200 F. The tests conducted include the evaluation of matrix modulus and strength, coefficients of thermal expansion, and fracture toughness. Though the experimental program is at an early stage, the data appear to indicate that these parameters are influenced by hard vacuum.

  1. Nanosecond laser pulses for mimicking thermal effects on nanostructured tungsten-based materials

    Science.gov (United States)

    Besozzi, E.; Maffini, A.; Dellasega, D.; Russo, V.; Facibeni, A.; Pazzaglia, A.; Beghi, M. G.; Passoni, M.

    2018-03-01

    In this work, we exploit nanosecond laser irradiation as a compact solution for investigating the thermomechanical behavior of tungsten materials under extreme thermal loads at the laboratory scale. Heat flux factor thresholds for various thermal effects, such as melting, cracking and recrystallization, are determined under both single and multishot experiments. The use of nanosecond lasers for mimicking thermal effects induced on W by fusion-relevant thermal loads is thus validated by direct comparison of the thresholds obtained in this work and the ones reported in the literature for electron beams and millisecond laser irradiation. Numerical simulations of temperature and thermal stress performed on a 2D thermomechanical code are used to predict the heat flux factor thresholds of the different thermal effects. We also investigate the thermal effect thresholds of various nanostructured W coatings. These coatings are produced by pulsed laser deposition, mimicking W coatings in tokamaks and W redeposited layers. All the coatings show lower damage thresholds with respect to bulk W. In general, thresholds decrease as the porosity degree of the materials increases. We thus propose a model to predict these thresholds for coatings with various morphologies, simply based on their porosity degree, which can be directly estimated by measuring the variation of the coating mass density with respect to that of the bulk.

  2. Thermal analysis on organic phase change materials for heat storage applications

    Science.gov (United States)

    Lager, Daniel

    2016-07-01

    In this paper, methodologies based on thermal analysis to evaluate specific heat capacity, phase transition enthalpies, thermal cycling stability and thermal conductivity of organic phase change materials (PCMs) are discussed. Calibration routines for a disc type heat flow differential scanning calorimetry (hf-DSC) are compared and the applied heating rates are adapted due to the low thermal conductivity of the organic PCMs. An assessment of thermal conductivity measurements based on "Laser Flash Analysis" (LFA) and the "Transient Hot Bridge" method (THB) in solid and liquid state has been performed. It could be shown that a disc type hf-DSC is a useful method for measuring specific heat capacity, melting enthalpies and cycling stability of organic PCM if temperature and sensitivity calibration are adapted to the material and quantity to be measured. The LFA method shows repeatable and reproducible thermal diffusivity results in solid state and a high effort for sample preparation in comparison to THB in liquid state. Thermal conductivity results of the two applied methods show large deviations in liquid phase and have to be validated by further experiments.

  3. Monte Carlo simulation of electron thermalization in scintillator materials: Implications for scintillator nonproportionality

    Energy Technology Data Exchange (ETDEWEB)

    Prange, Micah P. [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Xie, YuLong [Energy and Environment Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Campbell, Luke W. [National Security Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA; Gao, Fei [Department of Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, Michigan 48109, USA; Kerisit, Sebastien [Physical and Computational Sciences Directorate, Pacific Northwest National Laboratory, Richland, Washington 99352, USA

    2017-12-21

    The lack of reliable quantitative estimates of the length and time scales associated with hot electron thermalization after a gamma-ray induced energy cascade obscures the interplay of various microscopic processes controlling scintillator performance and hampers the search for improved detector materials. We apply a detailed microscopic kinetic Monte Carlo model of the creation and subsequent thermalization of hot electrons produced by gamma irradiation of six important scintillating crystals to determine the spatial extent of the cloud of excitations produced by gamma rays and the time required for the cloud to thermalize with the host lattice. The main ingredients of the model are ensembles of microscopic track structures produced upon gamma excitation (including the energy distribution of the excited carriers), numerical estimates of electron-phonon scattering rates, and a calculated particle dispersion to relate the speed and energy of excited carriers. All these ingredients are based on first-principles density functional theory calculations of the electronic and phonon band structures of the materials. Details of the Monte Carlo model are presented along with results for thermalization time and distance distributions. These results are discussed in light of previous work. It is found that among the studied materials, calculated thermalization distances are positively correlated with measured nonproportionality. In the important class of halide scintillators, the particle dispersion is found to be more influential than the largest phonon energy in determining the thermalization distance.

  4. Ways to improve physical and thermal performance of refractory lining materials

    Directory of Open Access Journals (Sweden)

    Khlystov A.I.

    2017-01-01

    Full Text Available Refractory lining materials, which include ceramic refractories and nonfired heat-resistant concretes, have a very short lifespan during the turnaround time measured in years and sometimes months. Therefore, increasing the service life of thermal generating units by 1.5-2 times will bring significant economic benefits. The main factor that determines the durability of refractory lining materials is the thermal resistance. It is possible to increase the thermal resistance by improving such physical and mechanical properties as strength and density. As for the ceramic refractory performance improvement, such technological methods as their structural and chemical modification by phosphate binder impregnation, as well as introduction of phosphate components into the ceramic batches during the molding process increase, in particular, their thermal stability. The use of aluminous and high-alumina cements contributes to a significant increase of not only strength, but also physical and thermal performance of heat-resistant concretes with different fillers. Switching to the use of chemical binders in the compositions of heat-resistant concretes (liquid glass with effective hardeners; silicate-block and phosphate binders enables to develop high-heat resistant materials which do not soften in a wide range of heating temperatures from 400 °С to 1600 °С. The positive results on increasing the thermal resistance of heat-resistant composites can be obtained by reinforcing them with high temperature fibers.

  5. Dynamic response analysis of an aircraft structure under thermal-acoustic loads

    International Nuclear Information System (INIS)

    Cheng, H; Li, H B; Zhang, W; Wu, Z Q; Liu, B R

    2016-01-01

    Future hypersonic aircraft will be exposed to extreme combined environments includes large magnitude thermal and acoustic loads. It presents a significant challenge for the integrity of these vehicles. Thermal-acoustic test is used to test structures for dynamic response and sonic fatigue due to combined loads. In this research, the numerical simulation process for the thermal acoustic test is presented, and the effects of thermal loads on vibro-acoustic response are investigated. To simulate the radiation heating system, Monte Carlo theory and thermal network theory was used to calculate the temperature distribution. Considering the thermal stress, the high temperature modal parameters are obtained with structural finite element methods. Based on acoustic finite element, modal-based vibro-acoustic analysis is carried out to compute structural responses. These researches are very vital to optimum thermal-acoustic test and structure designs for future hypersonic vehicles structure (paper)

  6. Study on paraffin/expanded graphite composite phase change thermal energy storage material

    International Nuclear Information System (INIS)

    Zhang Zhengguo; Fang Xiaoming

    2006-01-01

    A paraffin/expanded graphite composite phase change thermal energy storage material was prepared by absorbing the paraffin into an expanded graphite that has an excellent absorbability. In such a composite, the paraffin serves as a latent heat storage material and the expanded graphite acts as the supporting material, which prevents leakage of the melted paraffin from its porous structure due to the capillary and surface tension forces. The inherent structure of the expanded graphite did not change in the composite material. The solid-liquid phase change temperature of the composite PCM was the same as that of the paraffin, and the latent heat of the paraffin/expanded graphite composite material was equivalent to the calculated value based on the mass ratio of the paraffin in the composite. The heat transfer rate of the paraffin/expanded graphite composite was obviously higher than that of the paraffin due to the combination with the expanded graphite that had a high thermal conductivity. The prepared paraffin/expanded graphite composite phase change material had a large thermal storage capacity and improved thermal conductivity and did not experience liquid leakage during its solid-liquid phase change

  7. Thermal characterization of a new effective building material based on clay and olive waste

    Directory of Open Access Journals (Sweden)

    Mohamed Lamrani

    2018-01-01

    Full Text Available The influence of thermophysical properties of wall materials on energy performance and comfort in traditional building was investigated. The clay is the most commonly used sustainable building material. The study looked at the effects of the addition of pomace olive on the thermophysical properties of clay bricks to improve the energy efficiency of this ecological material. An experimental measurement of thermal properties of clay mixed with pomace olive was carried out by using the transient and steady state hot-plate and flash methods. The experimental methods are applied to measure the thermal properties of the composite material. The estimation of these thermal characteristics is based on a one dimensional model and the experimental errors are found less than 3%. The composite samples were prepared with different granular classes and mass fractions of the pomace olive in the mixture. The results show that the density of the new material was not substantially influenced by the size of the pomace olive. However, the thermal conductivity and diffusivity decrease from 0.65 W.m-1.K-1 and 4.21×10-7 m2.s-1 to 0.29 W.m-1.K-1 and 2.47×10-7m2.s-1, respectively, according to the variation of the volume fraction of pomace olive from 0 (pure clay to 71% showing that the olive pomace can be used as effective secondary raw materials in the making of clay bricks.

  8. Comparative Response of Four Pedogenic Soil Materials to Cement ...

    African Journals Online (AJOL)

    A comparative response of four Pedogenic soil materials to cement stabilization was investigated. The studies focused on the compaction characteristics, the unconfined sompressive strength and the California bearing ratio of the samples. The results obtained show that soil materials from Maiduguri responded favorably to ...

  9. Modelling of thermal shock experiments of carbon based materials in JUDITH

    International Nuclear Information System (INIS)

    Ogorodnikova, O.V.; Pestchanyi, S.; Koza, Y.; Linke, J.

    2005-01-01

    The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments

  10. Modelling of thermal shock experiments of carbon based materials in JUDITH

    Energy Technology Data Exchange (ETDEWEB)

    Ogorodnikova, O.V. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany)]. E-mail: o.ogorodnikova@fz-juelich.de; Pestchanyi, S. [Forschungszentrum Karlsruhe, EURATOM-Associaton, IHM, 76021 Karlsruhe (Germany); Koza, Y. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany); Linke, J. [Forschungszentrum Juelich, EURATOM-Association, IWV-2, 52425 Juelich (Germany)

    2005-03-01

    The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

  11. Modelling of thermal shock experiments of carbon based materials in JUDITH

    Science.gov (United States)

    Ogorodnikova, O. V.; Pestchanyi, S.; Koza, Y.; Linke, J.

    2005-03-01

    The interaction of hot plasma with material in fusion devices can result in material erosion and irreversible damage. Carbon based materials are proposed for ITER divertor armour. To simulate carbon erosion under high heat fluxes, electron beam heating in the JUDITH facility has been used. In this paper, carbon erosion under energetic electron impact is modeled by the 3D thermomechanics code 'PEGASUS-3D'. The code is based on a crack generation induced by thermal stress. The particle emission observed in thermal shock experiments is a result of breaking bonds between grains caused by thermal stress. The comparison of calculations with experimental data from JUDITH shows good agreement for various incident power densities and pulse durations. A realistic mean failure stress has been found. Pre-heating of test specimens results in earlier onset of brittle destruction and enhanced particle loss in agreement with experiments.

  12. Investigation of thermal effect on exterior wall surface of building material at urban city area

    Energy Technology Data Exchange (ETDEWEB)

    Md Din, Mohd Fadhil; Dzinun, Hazlini; Ponraj, M.; Chelliapan, Shreeshivadasan; Noor, Zainura Zainun [Institute of Environmental Water Resources and Management (IPASA), Faculty of Civil Engineering, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Remaz, Dilshah [Faculty of Built Environment, Universiti Teknologi Malaysia, 81310 UTM Skudai, Johor (Malaysia); Iwao, Kenzo [Nagoya Institute of Technology, Nagoya (Japan)

    2012-07-01

    This paper describes the investigation of heat impact on the vertical surfaces of buildings based on their thermal behavior. The study was performed based on four building materials that is commonly used in Malaysia; brick, concrete, granite and white concrete tiles. The thermal performances on the building materials were investigated using a surface temperature sensor, data logging system and infrared thermography. Results showed that the brick had the capability to absorb and store heat greater than other materials during the investigation period. The normalized heat (total heat/solar radiation) of the brick was 0.093 and produces high heat (51% compared to granite), confirming a substantial amount of heat being released into the atmosphere through radiation and convection. The most sensitive material that absorbs and stores heat was in the following order: brick > concrete > granite > white concrete tiles. It was concluded that the type of exterior wall material used in buildings had significant impact to the environment.

  13. 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.

  14. 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.

  15. Thermally Stable Heterocyclic Imines as New Potential Nonlinear Optical Materials

    Science.gov (United States)

    Nesterov, Volodymyr V.; Antipin, Mikhail Y.; Nesterov, Vladimir N.; Moore, Craig E.; Cardelino, Beatriz H.; Timofeeva, Tatiana V.

    2004-01-01

    In the course of a search for new thermostable acentric nonlinear optical crystalline materials, several heterocyclic imine derivatives were designed, with the general structure D-pi-A(D'). Introduction of a donor amino group (D') into the acceptor moiety was expected to bring H-bonds into their crystal structures, and so to elevate their melting points and assist in an acentric molecular packing. Six heterocycle-containing compounds of this type were prepared, single crystals were grown for five of them, and these crystals were characterized by X-ray analysis. A significant melting temperature elevation was found for all of the synthesized compounds. Three of the compounds were also found to crystallize in acentric space groups. One of the acentric compounds is built as a three-dimensional H-bonded molecular network. In the other two compounds, with very similar molecular structure, the molecules form one-dimensional H-bonded head-to-head associates (chains). These chains are parallel in two different crystallographic directions and form very unusual interpenetrating chain patterns in an acentric crystal. Two of the compounds crystallized with centrosymmetric molecular packing.

  16. A Study on Accelerated Thermal Aging of High Modulus Carbon/Epoxy Composite Material

    Directory of Open Access Journals (Sweden)

    Ju Min Kyung

    2015-01-01

    Full Text Available Composite materials have been used increasingly for various space applications due to the favorable characteristic of high modulus to density ratio and potential for near-zero coefficient of thermal expansion. In composite system, depending on the orientation of fibers, strength and stiffness can be changed so that the optimum structure can be accomplished. This is because the coefficient of thermal expansion (CTE of carbon fibers is negative. For spacecraft and orbiting space structure, which are thermally cycled by moving through the earth' shadow for at least 5 years, it is necessary to investigate the change of properties of the material over time. In this study, thermal aging of epoxy matrix/high modulus carbon fiber composite materials are accelerated to predict the long term creep property. Specimens are tested at various temperatures of 100~140°C with dynamic mechanical analysis to obtain creep compliances that are functions of time and temperature. Using Time Temperature Superposition method, creep compliance curves at each temperature are shifted to the reference temperature by shift factor and a master curve is generated at the reference temperature. This information is useful to predict the long term thermal aging of high modulus composite material for spacecraft application.

  17. Thermally responsive polymer systems for self-healing, reversible adhesion and shape memory applications

    Science.gov (United States)

    Luo, Xiaofan

    Responsive polymers are "smart" materials that are capable of performing prescribed, dynamic functions under an applied stimulus. In this dissertation, we explore several novel design strategies to develop thermally responsive polymers and polymer composites for self-healing, reversible adhesion and shape memory applications. In the first case described in Chapters 2 and 3, a thermally triggered self-healing material was prepared by blending a high-temperature epoxy resin with a thermoplastic polymer, poly(epsilon-caprolactone) (PCL). The initially miscible system undergoes polymerization induced phase separation (PIPS) during the curing of epoxy and yields a variety of compositionally dependent morphologies. At a particular PCL loading, the cured blend displays a "bricks-and-mortar" morphology in which epoxy exists as interconnected spheres ("bricks") within a continuous PCL matrix ("mortar"). A heat induced "bleeding" phenomenon was observed in the form of spontaneous wetting of all free surfaces by the molten PCL, and is attributed to the volumetric thermal expansion of PCL above its melting point in excess of epoxy brick expansion, which we term differential expansive bleeding (DEB). This DEB is capable of healing damage such as cracks. In controlled self-healing experiments, heating of a cracked specimen led to PCL bleeding from the bulk that yields a liquid layer bridging the crack gap. Upon cooling, a "scar" composed of PCL crystals was formed at the site of the crack, restoring a significant portion of mechanical strength. We further utilized DEB to enable strong and thermally-reversible adhesion of the material to itself and to metallic substrates, without any requirement for macroscopic softening or flow. After that, Chapters 4--6 present a novel composite strategy for the design and fabrication of shape memory polymer composites. The basic approach involves physically combining two or more functional components into an interpenetrating fiber

  18. 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.

  19. Nuclear power plant accident simulations of gasket materials under simultaneous radiation plus thermal plus mechanical stress conditions

    International Nuclear Information System (INIS)

    Gillen, K.T.; Malone, G.M.

    1997-07-01

    In order to probe the response of silicone door gasket materials to a postulated severe accident in an Italian nuclear power plant, compression stress relaxation (CSR) and compression set (CS) measurements were conducted under combined radiation (approximately 6 kGy/h) and temperature (up to 230 degrees C) conditions. By making some reasonable initial assumptions, simplified constant temperature and dose rates were derived that should do a reasonable job of simulating the complex environments for worst-case severe events that combine overall aging plus accidents. Further simplification coupled with thermal-only experiments allowed us to derive thermal-only conditions that can be used to achieve CSR and CS responses similar to those expected from the combined environments that are more difficult to simulate. Although the thermal-only simulations should lead to sealing forces similar to those expected during a severe accident, modulus and density results indicate that significant differences in underlying chemistry are expected for the thermal-only and the combined environment simulations. 15 refs., 31 figs., 15 tabs

  20. Thermal effects on transducer material for heat assisted magnetic recording application

    Energy Technology Data Exchange (ETDEWEB)

    Ji, Rong, E-mail: Ji-Rong@dsi.a-star.edu.sg; Xu, Baoxi; Cen, Zhanhong; Ying, Ji Feng; Toh, Yeow Teck [Data Storage Institute, Agency for Science, Technology and Research (A-STAR), 5 Engineering Drive 1, Singapore 117608 (Singapore)

    2015-05-07

    Heat Assisted Magnetic Recording (HAMR) is a promising technology for next generation hard disk drives with significantly increased data recording capacities. In HAMR, an optical near-field transducer (NFT) is used to concentrate laser energy on a magnetic recording medium to fulfill the heat assist function. The key components of a NFT are transducer material, cladding material, and adhesion material between the cladding and the transducer materials. Since transducer materials and cladding materials have been widely reported, this paper focuses on the adhesion materials between the Au transducer and the Al{sub 2}O{sub 3} cladding material. A comparative study for two kinds of adhesion material, Ta and Cr, has been conducted. We found that Ta provides better thermal stability to the whole transducer than Cr. This is because after thermal annealing, chromium forms oxide material at interfaces and chromium atoms diffuse remarkably into the Au layer and react with Au to form Au alloy. This study also provides insights on the selection of adhesion material for HAMR transducer.

  1. Thermal conductivity model for powdered materials under vacuum based on experimental studies

    Directory of Open Access Journals (Sweden)

    N. Sakatani

    2017-01-01

    Full Text Available The thermal conductivity of powdered media is characteristically very low in vacuum, and is effectively dependent on many parameters of their constituent particles and packing structure. Understanding of the heat transfer mechanism within powder layers in vacuum and theoretical modeling of their thermal conductivity are of great importance for several scientific and engineering problems. In this paper, we report the results of systematic thermal conductivity measurements of powdered media of varied particle size, porosity, and temperature under vacuum using glass beads as a model material. Based on the obtained experimental data, we investigated the heat transfer mechanism in powdered media in detail, and constructed a new theoretical thermal conductivity model for the vacuum condition. This model enables an absolute thermal conductivity to be calculated for a powder with the input of a set of powder parameters including particle size, porosity, temperature, and compressional stress or gravity, and vice versa. Our model is expected to be a competent tool for several scientific and engineering fields of study related to powders, such as the thermal infrared observation of air-less planetary bodies, thermal evolution of planetesimals, and performance of thermal insulators and heat storage powders.

  2. Optically-controlled long-term storage and release of thermal energy in phase-change materials

    OpenAIRE

    Han, Grace G. D.; Li, Huashan; Grossman, Jeffrey C.

    2017-01-01

    Thermal energy storage offers enormous potential for a wide range of energy technologies. Phase-change materials offer state-of-the-art thermal storage due to high latent heat. However, spontaneous heat loss from thermally charged phase-change materials to cooler surroundings occurs due to the absence of a significant energy barrier for the liquid–solid transition. This prevents control over the thermal storage, and developing effective methods to address this problem has remained an elusive ...

  3. The role of heater thermal response in reactor thermal limits during oscillartory two-phase flows

    Energy Technology Data Exchange (ETDEWEB)

    Ruggles, A.E.; Brown, N.W. [Univ. of Tennessee, Knoxville, TN (United States); Vasil`ev, A.D. [Nuclear Safety Institute, Moscow, (Russian Federation); Wendel, M.W. [Oak Ridge National Lab., TN (United States)

    1995-09-01

    Analytical and numerical investigations of critical heat flux (CHF) and reactor thermal limits are conducted for oscillatory two-phase flows often associated with natural circulation conditions. It is shown that the CHF and associated thermal limits depend on the amplitude of the flow oscillations, the period of the flow oscillations, and the thermal properties and dimensions of the heater. The value of the thermal limit can be much lower in unsteady flow situations than would be expected using time average flow conditions. It is also shown that the properties of the heater strongly influence the thermal limit value in unsteady flow situations, which is very important to the design of experiments to evaluate thermal limits for reactor fuel systems.

  4. Thermal-Responsive Polymers for Enhancing Safety of Electrochemical Storage Devices.

    Science.gov (United States)

    Yang, Hui; Leow, Wan Ru; Chen, Xiaodong

    2018-03-01

    Thermal runway constitutes the most pressing safety issue in lithium-ion batteries and supercapacitors of large-scale and high-power density due to risks of fire or explosion. However, traditional strategies for averting thermal runaway do not enable the charging-discharging rate to change according to temperature or the original performance to resume when the device is cooled to room temperature. To efficiently control thermal runaway, thermal-responsive polymers provide a feasible and reversible strategy due to their ability to sense and subsequently act according to a predetermined sequence when triggered by heat. Herein, recent research progress on the use of thermal-responsive polymers to enhance the thermal safety of electrochemical storage devices is reviewed. First, a brief discussion is provided on the methods of preventing thermal runaway in electrochemical storage devices. Subsequently, a short review is provided on the different types of thermal-responsive polymers that can efficiently avoid thermal runaway, such as phase change polymers, polymers with sol-gel transitions, and polymers with positive temperature coefficients. The results represent the important development of thermal-responsive polymers toward the prevention of thermal runaway in next-generation smart electrochemical storage devices. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Short-term thermal response of rapidly solidified Type 304 stainless steel containing helium

    International Nuclear Information System (INIS)

    Clark, D.E.

    1988-06-01

    Type 304 stainless steel was heat treated for short times near its melting point in order to determine its microstructural response to thermal cycles typical of the near heat-affected zones of welding processes. The material was rapidly solidified as a powder by centrifugal atomization in a helium environment and consolidated by hot extrusion. Along with the ingot metallurgy material used for canning the powder prior to hot extrusion, it was heat treated using a Gleeble at temperatures of 1200 and 1300 degree C for times ranging from <1 to 1000 s, and the samples were examined for microstructure and the existence of porosity due to entrapped helium. At higher test temperatures and longer treatment times, the material developed extensive porosity, which was stabilized by the presence of helium and which may also have a role in anchoring grain boundaries and inhibiting grain growth. The powder material. At lower test temperatures and shorter treatment times, grain growth in the γ phase appeared to be restricted in the powder material, possible by the presence of helium. An intermediate temperatures and times, a γ-δ duplex microstructure also restricted grain growth again occurred in the δ microstructure. 9 refs., 14 figs., 3 tabs

  6. Responses on indoor thermal environment in selected dwellings ...

    African Journals Online (AJOL)

    This paper reports the results of a thermal comfort study conducted recently on 12 subjects in the hot season in Ibadan, located in the hot humid climate. A statistical sample was carried out on these subjects casting their thermal comfort votes at half-hourly basis in four major areas of the city between February and April.

  7. Radiometric Measurements of the Thermal Conductivity of Complex Planetary-like Materials

    Science.gov (United States)

    Piqueux, S.; Christensen, P. R.

    2012-12-01

    Planetary surface temperatures and thermal inertias are controlled by the physical and compositional characteristics of the surface layer material, which result from current and past geological activity. For this reason, temperature measurements are often acquired because they provide fundamental constraints on the geological history and habitability. Examples of regolith properties affecting surface temperatures and inertias are: grain sizes and mixture ratios, solid composition in the case of ices, presence of cement between grains, regolith porosity, grain roughness, material layering etc.. Other important factors include volatile phase changes, and endogenic or exogenic heat sources (i.e. geothermal heat flow, impact-related heat, biological activity etc.). In the case of Mars, the multitude of instruments observing the surface temperature at different spatial and temporal resolutions (i.e. IRTM, Thermoskan, TES, MiniTES, THEMIS, MCS, REMS, etc.) in conjunction with other instruments allows us to probe and characterize the thermal properties of the surface layer with an unprecedented resolution. While the derivation of thermal inertia values from temperature measurements is routinely performed by well-established planetary regolith numerical models, constraining the physical properties of the surface layer from thermal inertia values requires the additional step of laboratory measurements. The density and specific heat are usually constant and sufficiently well known for common geological materials, but the bulk thermal conductivity is highly variable as a function of the physical characteristics of the regolith. Most laboratory designs do not allow an investigation of the thermal conductivity of complex regolith configurations similar to those observed on planetary surfaces (i.e. cemented material, large grains, layered material, and temperature effects) because the samples are too small and need to be soft to insert heating or measuring devices. For this

  8. Temperature- and light-responsive smart polymer materials.

    Science.gov (United States)

    Jochum, Florian D; Theato, Patrick

    2013-09-07

    Stimuli-responsive polymers have been attracting great interest within the scientific community for several decades. The unique feature to respond to small changes in the environmental conditions has made this class of materials very promising for several applications in the field of nanoscience, nanotechnology and nanomedicine. So far, several different chemical, physical or biochemical stimuli have been investigated within natural or synthetic polymers. Very interesting and appealing seems to be the combination of several stimuli to tune the properties of these materials in manifold ways. Within this present review, we want to highlight the recent progress in the field of synthetic stimuli-responsive polymers combining temperature and light responsiveness.

  9. Thermal properties and modeling of aluminosilicate materials for low-temperature bulk applications

    International Nuclear Information System (INIS)

    Kaushal, S.

    1988-01-01

    This thesis concerns itself with the thermal properties of aluminosilicate materials such as cements, blended cements and clays and their application to the problem of radioactive waste encapsulation. The objective of this thesis is to study the thermal properties (heat of hydration, thermal conductivity and diffusivity) of these materials and to determine their effect on the temperature in large monoliths and on the material itself. In this thesis the hydration temperatures for the extreme conditions (adiabatic) were experimentally measured and compared to those predicted under real conditions. Such a simulation can be made by measuring the thermal properties and studying the temperature distribution predicted by a finite differences computer model. Measurements of adiabatic temperature rise were made using a computer-controlled adiabatic calorimeter which was designed and developed for this thesis. Conditions very close to zero heat exchange with the environment were achieved. The existence of this method made it possible to actually observe the fact that cement hydration results in boiling off of the water in such conditions. A number of additives were tried to prevent this. It was observed that waste or by-product materials such as blast furnace slag and fly ash could be used to dramatically reduced the temperature in large bodies. These materials also reacted extensively with the highly alkaline radioactive waste solution to form hydrogarnet and zeolitic material which had useful cementing properties. The conclusion was reached that a selection of blends of aluminosilicate materials can be utilized for providing the proper thermal environment for long-term geological disposal of radioactive waste

  10. Mapping Thermal Expansion Coefficients in Freestanding 2D Materials at the Nanometer Scale

    Science.gov (United States)

    Hu, Xuan; Yasaei, Poya; Jokisaari, Jacob; Öǧüt, Serdar; Salehi-Khojin, Amin; Klie, Robert F.

    2018-02-01

    Two-dimensional materials, including graphene, transition metal dichalcogenides and their heterostructures, exhibit great potential for a variety of applications, such as transistors, spintronics, and photovoltaics. While the miniaturization offers remarkable improvements in electrical performance, heat dissipation and thermal mismatch can be a problem in designing electronic devices based on two-dimensional materials. Quantifying the thermal expansion coefficient of 2D materials requires temperature measurements at nanometer scale. Here, we introduce a novel nanometer-scale thermometry approach to measure temperature and quantify the thermal expansion coefficients in 2D materials based on scanning transmission electron microscopy combined with electron energy-loss spectroscopy to determine the energy shift of the plasmon resonance peak of 2D materials as a function of sample temperature. By combining these measurements with first-principles modeling, the thermal expansion coefficients (TECs) of single-layer and freestanding graphene and bulk, as well as monolayer MoS2 , MoSe2 , WS2 , or WSe2 , are directly determined and mapped.

  11. Correction Effect of Finite Pulse Duration for High Thermal Diffusivity Materials

    International Nuclear Information System (INIS)

    Park, Dae Gyu; Kim, Hee Moon; Baik, Seung Je; Yoo, Byoung Ok; Ahn, Sang Bok; Ryu, Woo Seok

    2010-01-01

    In the laser pulsed flash method, a pulse of energy is incident on one of two parallel faces of a sample. The subsequent temperature history of the opposite face is then related to the thermal diffusivity. When the heat pulse is of infinitesimal duration, the diffusivity is obtained from the transient response of the rear face temperature proposed by Parker et al. The diffusivity αis computed from relation 2222121.37cattαππ≡= (1) Where a is the sample thickness and is the time required for the rear face temperature to reach half-maximum, and t c ≡a 2 / π 2 t 1/2 is the characteristic rise time of the rear face temperature. When the pulse-time 1/2tτis not infinitesimal, but becomes comparable to tc, it is apparent that the rise in temperature of the rear face will be retarded, and will be greater than 1.37 t c . This retardation has been called the ' finite pulse-time effect.' Equation (1) is accurate to 1% for tc > ∼ 501/2tτ. For many substances, this inequality cannot be achieved with conventional optical sources (e.g. τ. 10 -3 sec for a solid state laser) unless the sample thickness is so large that its rise in temperature is too small for accurate measurement. One must therefore make an appropriate correction for the retardation of the temperature wave. Purpose of study are to observe impact of finite pulse time effect in appropriate sample thickness and to verify the effect of pulse correction using Cape and Lehman method for high thermal diffusivity materials

  12. Experimental data showing the thermal behavior of a flat roof with phase change material.

    Science.gov (United States)

    Tokuç, Ayça; Başaran, Tahsin; Yesügey, S Cengiz

    2015-12-01

    The selection and configuration of building materials for optimal energy efficiency in a building require some assumptions and models for the thermal behavior of the utilized materials. Although the models for many materials can be considered acceptable for simulation and calculation purposes, the work for modeling the real time behavior of phase change materials is still under development. The data given in this article shows the thermal behavior of a flat roof element with a phase change material (PCM) layer. The temperature and energy given to and taken from the building element are reported. In addition the solid-liquid behavior of the PCM is tracked through images. The resulting thermal behavior of the phase change material is discussed and simulated in [1] A. Tokuç, T. Başaran, S.C. Yesügey, An experimental and numerical investigation on the use of phase change materials in building elements: the case of a flat roof in Istanbul, Build. Energy, vol. 102, 2015, pp. 91-104.

  13. Experimental data showing the thermal behavior of a flat roof with phase change material

    Directory of Open Access Journals (Sweden)

    Ayça Tokuç

    2015-12-01

    Full Text Available The selection and configuration of building materials for optimal energy efficiency in a building require some assumptions and models for the thermal behavior of the utilized materials. Although the models for many materials can be considered acceptable for simulation and calculation purposes, the work for modeling the real time behavior of phase change materials is still under development. The data given in this article shows the thermal behavior of a flat roof element with a phase change material (PCM layer. The temperature and energy given to and taken from the building element are reported. In addition the solid–liquid behavior of the PCM is tracked through images. The resulting thermal behavior of the phase change material is discussed and simulated in [1] A. Tokuç, T. Başaran, S.C. Yesügey, An experimental and numerical investigation on the use of phase change materials in building elements: the case of a flat roof in Istanbul, Build. Energy, vol. 102, 2015, pp. 91–104.

  14. Advances in the valorization of waste and by-product materials as thermal energy storage (TES) materials

    OpenAIRE

    Gutiérrez, Andrea; Miró, Laia; Gil, Antoni; Rodríguez Aseguinolaza, Javier; Barreneche Güerisoli, Camila; Calvet, Nicolas; Py, Xavier; Fernández Renna, Ana Inés; Grágeda, Mario; Ushak, Svetlana; Cabeza, Luisa F.

    2016-01-01

    Today, one of the biggest challenges our society must face is the satisfactory supply, dispatchability and management of the energy. Thermal Energy Storage (TES) has been identified as a breakthrough concept in industrial heat recovery applications and development of renewable technologies such as concentrated solar power (CSP) plants or compressed air energy storage (CAES). A wide variety of potential heat storage materials has been identified depending on the implemented TES method: sensibl...

  15. Scientific and Technical Challenges in Thermal Transport and Thermoelectric Materials and Devices

    KAUST Repository

    O'Dwyer, Colm

    2017-01-19

    This paper considers the state-of-the-art and open scientific and technological questions in thermoelectric materials and devices, from phonon engineering and scattering methods, to new and complex materials and their thermoelectric behavior. The paper also describes recent approaches to create structural and compositional material systems designed to enhance the thermoelectric figure of merit and power factors. We also summarize and contextualize recent advances in the use of superlattice structures and porosity or roughness to influence phonon scattering mechanisms and detail some advances in integrated thermoelectric materials for generators and coolers for thermally stable photonic devices.

  16. Scientific and Technical Challenges in Thermal Transport and Thermoelectric Materials and Devices

    KAUST Repository

    O'Dwyer, Colm; Chen, Renkun; He, Jr-Hau; Lee, Jaeho; Razeeb, Kafil M.

    2017-01-01

    This paper considers the state-of-the-art and open scientific and technological questions in thermoelectric materials and devices, from phonon engineering and scattering methods, to new and complex materials and their thermoelectric behavior. The paper also describes recent approaches to create structural and compositional material systems designed to enhance the thermoelectric figure of merit and power factors. We also summarize and contextualize recent advances in the use of superlattice structures and porosity or roughness to influence phonon scattering mechanisms and detail some advances in integrated thermoelectric materials for generators and coolers for thermally stable photonic devices.

  17. Stimuli-Responsive Materials for Controlled Release Applications

    KAUST Repository

    Li, Song

    2015-04-01

    The controlled release of therapeutics has been one of the major challenges for scientists and engineers during the past three decades. To address this outstanding problem, the design and fabrication of stimuli-responsive materials are pursued to guarantee the controlled release of cargo at a specific time and with an accurate amount. Upon applying different stimuli such as light, magnetic field, heat, pH change, enzymes or redox, functional materials change their physicochemical properties through physical transformation or chemical reactions, allowing the release of payload agents on demand. This dissertation studied three stimuli-responsive membrane systems for controlled release from films of macro sizes to microcapsules of nano sizes. The first membrane system is a polymeric composite film which can decrease and sustain diffusion upon light irradiation. The photo-response of membranes is based on the photoreaction of cinnamic derivatives. The second one is composite membrane which can improve diffusion upon heating. The thermo-response of membranes comes from the volume phase transition ability of hydrogels. The third one is microcapsule which can release encapsulated agents upon light irradiation. The photo-response of capsules results from the photoreaction of nitrobenzyl derivatives. The study on these membrane systems reveals that stimuli-responsive release can be achieved by utilizing different functional materials on either macro or micro level. Based on the abundant family of smart materials, designing and fabricating stimuli-responsive systems shall lead to various advanced release processes on demand for biomedical applications.

  18. Two-photon fluorescent polysiloxane-based films with thermally responsive self switching properties achieved by a unique reversible spirocyclization mechanism.

    Science.gov (United States)

    Zuo, Yujing; Yang, Tingxin; Zhang, Yu; Gou, Zhiming; Tian, Minggang; Kong, Xiuqi; Lin, Weiying

    2018-03-14

    Responsiveness and reversibility are present in nature, and are ubiquitous in biological systems. The realization of reversibility and responsiveness is of great importance in the development of properties and the design of new materials. However, two-photon fluorescent thermal-responsive materials have not been reported to date. Herein, we engineered thermally responsive polysiloxane materials ( Dns-non ) that exhibited unique two-photon luminescence, and this is the first report about thermally responsive luminescent materials with two-photon fluorescence. The fluorescence of Dns-non could switch from the "on" to "off" state through a facile heating and cooling process, which could be observed by the naked eye. Monitoring the temperature of the CPU in situ was achieved by easily coating D1-non onto the CPU surface, which verified the potential application in devices of Dns-non . A unique alkaline tuned reversible transition mechanism of rhodamine-B from its spirocyclic to its ring-open state was proposed. Furthermore, Dns-non appeared to be a useful cell adhesive for the culture of cells on the surface. We believe that the constructed thermally responsive silicon films which have promising utilization as a new type of functional fluorescent material, may show broad applications in materials chemistry or bioscience.

  19. Thermal transport in phosphorene and phosphorene-based materials: A review on numerical studies

    Science.gov (United States)

    Hong, Yang; Zhang, Jingchao; Zeng, Xiao Cheng

    2018-03-01

    The recently discovered two-dimensional (2D) layered material phosphorene has attracted considerable interest as a promising p-type semiconducting material. In this article, we review the recent advances in numerical studies of the thermal properties of monolayer phosphorene and phosphorene-based heterostructures. We first briefly review the commonly used first-principles and molecular dynamics (MD) approaches to evaluate the thermal conductivity and interfacial thermal resistance of 2D phosphorene. Principles of different steady-state and transient MD techniques have been elaborated on in detail. Next, we discuss the anisotropic thermal transport of phosphorene in zigzag and armchair chiral directions. Subsequently, the in-plane and cross-plane thermal transport in phosphorene-based heterostructures such as phosphorene/silicon and phosphorene/graphene is summarized. Finally, the numerical research in the field of thermal transport in 2D phosphorene is highlighted along with our perspective of potentials and opportunities of 2D phosphorenes in electronic applications such as photodetectors, field-effect transistors, lithium ion batteries, sodium ion batteries, and thermoelectric devices.

  20. Graphene-enhanced thermal interface materials for heat removal from photovoltaic solar cells

    Science.gov (United States)

    Saadah, M.; Gamalath, D.; Hernandez, E.; Balandin, A. A.

    2016-09-01

    The increase in the temperature of photovoltaic (PV) solar cells affects negatively their power conversion efficiency and decreases their lifetime. The negative effects are particularly pronounced in concentrator solar cells. Therefore, it is crucial to limit the PV cell temperature by effectively removing the excess heat. Conventional thermal phase change materials (PCMs) and thermal interface materials (TIMs) do not possess the thermal conductivity values sufficient for thermal management of the next generation of PV cells. In this paper, we report the results of investigation of the increased efficiency of PV cells with the use of graphene-enhanced TIMs. Graphene reveals the highest values of the intrinsic thermal conductivity. It was also shown that the thermal conductivity of composites can be increased via utilization of graphene fillers. We prepared TIMs with up to 6% of graphene designed specifically for PV cell application. The solar cells were tested using the solar simulation module. It was found that the drop in the output voltage of the solar panel under two-sun concentrated illumination can be reduced from 19% to 6% when grapheneenhanced TIMs are used. The proposed method can recover up to 75% of the power loss in solar cells.

  1. Preparation and Thermal Properties of Eutectic Hydrate Salt Phase Change Thermal Energy Storage Material

    OpenAIRE

    Liang, Lin; Chen, Xi

    2018-01-01

    In this study, a new cold storage phase change material eutectic hydrate salt (K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O) was prepared, modified, and tested. The modification was performed by adding a nucleating agent and thickener. The physical properties such as viscosity, surface tension, cold storage characteristics, supercooling, and the stability during freeze-thaw cycles were studied. Results show that the use of nucleating agents, such as sodium tetraborate, sodium fluoride, and nanoparti...

  2. Apparatus and test method for characterizing the temperature regulating properties of thermal functional porous polymeric materials.

    Science.gov (United States)

    Yao, Bao-Guo; Zhang, Shan; Zhang, De-Pin

    2017-05-01

    In order to evaluate the temperature regulating properties of thermal functional porous polymeric materials such as fabrics treated with phase change material microcapsules, a new apparatus was developed. The apparatus and the test method can measure the heat flux, temperature, and displacement signals during the dynamic contact and then quickly give an evaluation for the temperature regulating properties by simulating the dynamic heat transfer and temperature regulating process when the materials contact the body skin. A series of indices including the psychosensory intensity, regulating capability index, and relative regulating index were defined to characterize the temperature regulating properties. The measurement principle, the evaluation criteria and grading method, the experimental setup and the test results discussion, and the gage capability analysis of the apparatus are presented. The new apparatus provides a method for the objective measurement and evaluation of the temperature regulating properties of thermal functional porous polymeric materials.

  3. Compendium of information on identification and testing of materials for plastic solar thermal collectors

    Energy Technology Data Exchange (ETDEWEB)

    McGinniss, V.D.; Sliemers, F.A.; Landstrom, D.K.; Talbert, S.G.

    1980-07-31

    This report is intended to organize and summarize prior and current literature concerning the weathering, aging, durability, degradation, and testing methodologies as applied to materials for plastic solar thermal collectors. Topics covered include (1) rate of aging of polymeric materials; (2) environmental factors affecting performance; (3) evaluation and prediction of service life; (4) measurement of physical and chemical properties; (5) discussion of evaluation techniques and specific instrumentation; (6) degradation reactions and mechanisms; (7) weathering of specific polymeric materials; and (8) exposure testing methodology. Major emphasis has been placed on defining the current state of the art in plastics degradation and on identifying information that can be utilized in applying appropriate and effective aging tests for use in projecting service life of plastic solar thermal collectors. This information will also be of value where polymeric components are utilized in the construction of conventional solar collectors or any application where plastic degradation and weathering are prime factors in material selection.

  4. Packaging strategies for printed circuit board components. Volume I, materials & thermal stresses.

    Energy Technology Data Exchange (ETDEWEB)

    Neilsen, Michael K. (Kansas City Plant, Kansas City, MO); Austin, Kevin N.; Adolf, Douglas Brian; Spangler, Scott W.; Neidigk, Matthew Aaron; Chambers, Robert S.

    2011-09-01

    Decisions on material selections for electronics packaging can be quite complicated by the need to balance the criteria to withstand severe impacts yet survive deep thermal cycles intact. Many times, material choices are based on historical precedence perhaps ignorant of whether those initial choices were carefully investigated or whether the requirements on the new component match those of previous units. The goal of this program focuses on developing both increased intuition for generic packaging guidelines and computational methodologies for optimizing packaging in specific components. Initial efforts centered on characterization of classes of materials common to packaging strategies and computational analyses of stresses generated during thermal cycling to identify strengths and weaknesses of various material choices. Future studies will analyze the same example problems incorporating the effects of curing stresses as needed and analyzing dynamic loadings to compare trends with the quasi-static conclusions.

  5. Physiological responses to short-term thermal stress in mayfly (Neocloeon triangulifer) larvae in relation to upper thermal limits.

    Science.gov (United States)

    Kim, Kyoung Sun; Chou, Hsuan; Funk, David H; Jackson, John K; Sweeney, Bernard W; Buchwalter, David B

    2017-07-15

    Understanding species' thermal limits and their physiological determinants is critical in light of climate change and other human activities that warm freshwater ecosystems. Here, we ask whether oxygen limitation determines the chronic upper thermal limits in larvae of the mayfly Neocloeon triangulifer , an emerging model for ecological and physiological studies. Our experiments are based on a robust understanding of the upper acute (∼40°C) and chronic thermal limits of this species (>28°C, ≤30°C) derived from full life cycle rearing experiments across temperatures. We tested two related predictions derived from the hypothesis that oxygen limitation sets the chronic upper thermal limits: (1) aerobic scope declines in mayfly larvae as they approach and exceed temperatures that are chronically lethal to larvae; and (2) genes indicative of hypoxia challenge are also responsive in larvae exposed to ecologically relevant thermal limits. Neither prediction held true. We estimated aerobic scope by subtracting measurements of standard oxygen consumption rates from measurements of maximum oxygen consumption rates, the latter of which was obtained by treating with the metabolic uncoupling agent carbonyl cyanide-4-(trifluoromethoxy) pheylhydrazone (FCCP). Aerobic scope was similar in larvae held below and above chronic thermal limits. Genes indicative of oxygen limitation (LDH, EGL-9) were only upregulated under hypoxia or during exposure to temperatures beyond the chronic (and more ecologically relevant) thermal limits of this species (LDH). Our results suggest that the chronic thermal limits of this species are likely not driven by oxygen limitation, but rather are determined by other factors, e.g. bioenergetics costs. We caution against the use of short-term thermal ramping approaches to estimate critical thermal limits (CT max ) in aquatic insects because those temperatures are typically higher than those that occur in nature. © 2017. Published by The Company of

  6. Phase change material thermal storage for biofuel preheating in micro trigeneration application: A numerical study

    International Nuclear Information System (INIS)

    Wu, Dawei; Chen, Junlong; Roskilly, Anthony P.

    2015-01-01

    Highlights: • Engine exhaust heat driven phase change material thermal storage. • Fuel preheating for direct use of straight plant oil on diesel engine. • CFD aided design of the phase change material thermal storage. • Melting and solidification model considering natural convection. - Abstract: A biofuel micro trigeneration prototype has been developed to utilise local energy crop oils as fuel in rural areas and developing countries. Straight plant oils (SPOs) only leave behind very little carbon footprint during its simply production process compared to commercial biodiesels in refineries, but the high viscosity of SPOs causes difficulties at engine cold starts, which further results in poor fuel atomisation, compromised engine performance and fast engine deterioration. In this study, a phase change material (PCM) thermal storage is designed to recover and store engine exhaust heat to preheat SPOs at cold starts. High temperature commercial paraffin is selected as the PCM to meet the optimal preheating temperature range of 70–90 °C, in terms of the SPO property study. A numerical model of the PCM thermal storage is developed and validated by references. The PCM melting and solidification processes with the consideration of natural convection in liquid zone are simulated in ANSYS-FLUENT to verify the feasibility of the PCM thermal storage as a part of the self-contained biofuel micro trigeneration prototype

  7. Thermal properties variations in unconsolidated material for very shallow geothermal application (ITER project)

    Science.gov (United States)

    Sipio, Eloisa Di; Bertermann, David

    2018-04-01

    In engineering, agricultural and meteorological project design, sediment thermal properties are highly important parameters, and thermal conductivity plays a fundamental role when dimensioning ground heat exchangers, especially in very shallow geothermal systems. Herein, the first 2 m of depth from surface is of critical importance. However, the heat transfer determination in unconsolidated material is difficult to estimate, as it depends on several factors, including particle size, bulk density, water content, mineralogy composition and ground temperature. The performance of a very shallow geothermal system, as a horizontal collector or heat basket, is strongly correlated to the type of sediment at disposal and rapidly decreases in the case of dry-unsaturated conditions. The available experimental data are often scattered, incomplete and do not fully support thermo-active ground structure modeling. The ITER project, funded by the European Union, contributes to a better knowledge of the relationship between thermal conductivity and water content, required for understanding the very shallow geothermal systems behaviour in saturated and unsaturated conditions. So as to enhance the performance of horizontal geothermal heat exchangers, thermally enhanced backfilling material were tested in the laboratory, and an overview of physical-thermal properties variations under several moisture and load conditions for different mixtures of natural material was here presented.

  8. Experimental study of thermal conductivity of pyrolysised materials by means of a flat layer

    Science.gov (United States)

    Vaniushkin, V. D.; Popov, S. K.; Sidenkov, D. V.

    2017-11-01

    Recycling of tires is currently a very important task. One of the areas of recycling tires is their low-temperature pyrolysis to produce marketable products - liquid fraction and a solid coke residue. For the development of the pyrolysis installation it is important to know the thermal conductivity of the coke residue at different temperatures of pyrolysis of initial material. As a property of matter, thermal conductivity depends in general on temperature and pressure. For materials with some structure, such as porous materials, the thermal conductivity depends on the characteristics of the structure. The thermal conductivity of the porous coke residue at pyrolysis temperatures of 300 0C, 400 0C, 500 0C and atmospheric pressure was studied experimentally at the laboratory unit of the department of “Theoretical basis of heat engineering” using the method of the flat layer in the temperature range 5…100 0C. Experimentally proved temperature dependencies of the coefficient of thermal conductivity of the coke residue are built to improve the accuracy of calculations of constructive and regime parameters of the pyrolysis installation.

  9. From biowaste to magnet-responsive materials for water remediation from polycyclic aromatic hydrocarbons.

    Science.gov (United States)

    Nisticò, Roberto; Cesano, Federico; Franzoso, Flavia; Magnacca, Giuliana; Scarano, Domenica; Funes, Israel G; Carlos, Luciano; Parolo, Maria E

    2018-07-01

    Composted urban biowaste-derived substances (BBS-GC) are used as carbon sources for the preparation of carbon-coated magnet-sensitive nanoparticles obtained via co-precipitation method and the subsequent thermal treatment at 550 °C under nitrogen atmosphere. A multitechnique approach has been applied to investigate the morphology, magnetic properties, phase composition, thermal stability of the obtained magnet-sensitive materials. In particular, pyrolysis-induced modifications affecting the BBS-GC/carbon shell were highlighted. The adsorption capacity of such bio-derivative magnetic materials for the removal of hydrophobic contaminants such as polycyclic aromatic hydrocarbons was evaluated in order to verify their potential application in wastewater remediation process. The promising results suggest their use as a new generation of magnet-responsive easily-recoverable adsorbents for water purification treatments. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Preparation and Thermal Properties of Eutectic Hydrate Salt Phase Change Thermal Energy Storage Material

    Directory of Open Access Journals (Sweden)

    Lin Liang

    2018-01-01

    Full Text Available In this study, a new cold storage phase change material eutectic hydrate salt (K2HPO4·3H2O–NaH2PO4·2H2O–Na2S2O3·5H2O was prepared, modified, and tested. The modification was performed by adding a nucleating agent and thickener. The physical properties such as viscosity, surface tension, cold storage characteristics, supercooling, and the stability during freeze-thaw cycles were studied. Results show that the use of nucleating agents, such as sodium tetraborate, sodium fluoride, and nanoparticles, are effective. The solidification temperature and latent heat of these materials which was added with 0, 3, and 5 wt% thickeners were −11.9, −10.6, and −14.8°C and 127.2, 118.6, 82.56 J/g, respectively. Adding a nucleating agent can effectively improve the nucleation rate and nucleation stability. Furthermore, increasing viscosity has a positive impact on the solidification rate, supercooling, and the stability during freeze-thaw cycles.

  11. High-performance ferroelectric and magnetoresistive materials for next-generation thermal detector arrays

    Science.gov (United States)

    Todd, Michael A.; Donohue, Paul P.; Watton, Rex; Williams, Dennis J.; Anthony, Carl J.; Blamire, Mark G.

    2002-12-01

    This paper discusses the potential thermal imaging performance achievable from thermal detector arrays and concludes that the current generation of thin-film ferroelectric and resistance bolometer based detector arrays are limited by the detector materials used. It is proposed that the next generation of large uncooled focal plane arrays will need to look towards higher performance detector materials - particularly if they aim to approach the fundamental performance limits and compete with cooled photon detector arrays. Two examples of bolometer thin-film materials are described that achieve high performance from operating around phase transitions. The material Lead Scandium Tantalate (PST) has a paraelectric-to-ferroelectric phase transition around room temperature and is used with an applied field in the dielectric bolometer mode for thermal imaging. PST films grown by sputtering and liquid-source CVD have shown merit figures for thermal imaging a factor of 2 to 3 times higher than PZT-based pyroelectric thin films. The material Lanthanum Calcium Manganite (LCMO) has a paramagnetic to ferromagnetic phase transition around -20oC. This paper describes recent measurements of TCR and 1/f noise in pulsed laser-deposited LCMO films on Neodymium Gallate substrates. These results show that LCMO not only has high TCR's - up to 30%/K - but also low 1/f excess noise, with bolometer merit figures at least an order of magnitude higher than Vanadium Oxide, making it ideal for the next generation of microbolometer arrays. These high performance properties come at the expense of processing complexities and novel device designs will need to be introduced to realize the potential of these materials in the next generation of thermal detectors.

  12. Detection and quantification of defects in composite material by using thermal wave method

    International Nuclear Information System (INIS)

    Ranjit, Shrestha; Kim, Won Tae

    2015-01-01

    This paper explored the results of experimental investigation on carbon fiber reinforced polymer (CFRP) composite sample with thermal wave technique. The thermal wave technique combines the advantages of both conventional thermal wave measurement and thermography using a commercial Infrared camera. The sample comprises the artificial inclusions of foreign material to simulate defects of different shape and size at different depths. Lock-in thermography is employed for the detection of defects. The temperature field of the front surface of sample was observed and analysed at several excitation frequencies ranging from 0.562 Hz down to 0.032 Hz. Four-point methodology was applied to extract the amplitude and phase of thermal wave's harmonic component. The phase images are analyzed to find qualitative and quantitative information about the defects

  13. A new method for measuring the thermal regulatory properties of phase change material (PCM) fabrics

    International Nuclear Information System (INIS)

    Wan, X; Fan, J

    2009-01-01

    Several methods already exist for the measurement of the thermal regulatory properties of fabrics containing phase change materials (PCMs). However, they do not adequately simulate the actual use condition; consequently the measurements may not have relevance to the performance of PCM fabrics in actual use. Here we report on the development of a new method, which better simulates the real use situation. In this method, a hot plate, simulating the human body, generates a constant amount of heat depending on the type of human activity to be simulated. The hot plate covered by the PCM fabric is then exposed to a thermal transient simulating a wearer moving from one thermal environment to another; the changes of surface temperature and heat loss of the hot plate are then recorded and used to characterize the thermal regulatory properties of the PCM fabrics

  14. 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.)

  15. Carbon nanotube/paraffin/montmorillonite composite phase change material for thermal energy storage.

    Science.gov (United States)

    Li, Min; Guo, Qiangang; Nutt, Steven

    2017-04-01

    A composite phase change material (PCM) comprised of organic montmorillonite (OMMT)/paraffin/grafted multi-walled nanotube (MWNT) is synthesized via ultrasonic dispersion and liquid intercalation. The microstructure of the composite PCM has been characterized to determine the phase distribution, and thermal properties (latent heat and thermal conductivity) have been measured by differential scanning calorimetry (DSC) and a thermal constant analyzer. The results show that paraffin molecules are intercalated in the montmorillonite layers and the grafted MWNTs are dispersed in the montmorillonite layers. The latent heat is 47.1 J/g, and the thermal conductivity of the OMMT/paraffin/grafted MWNT composites is 34% higher than that of the OMMT/paraffin composites and 65% higher than that of paraffin.

  16. Filler-depletion layer adjacent to interface impacts performance of thermal interface material

    Directory of Open Access Journals (Sweden)

    Susumu Yada

    2016-01-01

    Full Text Available When installing thermal interface material (TIM between heat source and sink to reduce contact thermal resistance, the interfacial thermal resistance (ITR between the TIM and heat source/sink may become important, especially when the TIM thickness becomes smaller in the next-generation device integration. To this end, we have investigated ITR between TIM and aluminum surface by using the time-domain thermoreflectance method. The measurements reveal large ITR attributed to the depletion of filler particles in TIM adjacent to the aluminum surface. The thickness of the depletion layer is estimated to be about 100 nm. As a consequence, the fraction of ITR to the total contact thermal resistance becomes about 20% when the TIM thickness is about 50 μm (current thickness, and it exceeds 50% when the thickness is smaller than 10 μm (next-generation thickness.

  17. Detection and quantification of defects in composite material by using thermal wave method

    Energy Technology Data Exchange (ETDEWEB)

    Ranjit, Shrestha; Kim, Won Tae [Dept. of Mechanical Engineering, Kongju National University, Cheonan (Korea, Republic of)

    2015-12-15

    This paper explored the results of experimental investigation on carbon fiber reinforced polymer (CFRP) composite sample with thermal wave technique. The thermal wave technique combines the advantages of both conventional thermal wave measurement and thermography using a commercial Infrared camera. The sample comprises the artificial inclusions of foreign material to simulate defects of different shape and size at different depths. Lock-in thermography is employed for the detection of defects. The temperature field of the front surface of sample was observed and analysed at several excitation frequencies ranging from 0.562 Hz down to 0.032 Hz. Four-point methodology was applied to extract the amplitude and phase of thermal wave's harmonic component. The phase images are analyzed to find qualitative and quantitative information about the defects.

  18. 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.

  19. Microencapsulated n-octacosane as phase change material for thermal energy storage

    Energy Technology Data Exchange (ETDEWEB)

    Sari, Ahmet; Alkan, Cemil; Karaipekli, Ali [Department of Chemistry, Gaziosmanpasa University, 60240 Tokat (Turkey); Uzun, Orhan [Department of Physics, Gaziosmanpasa University, 60240 Tokat (Turkey)

    2009-10-15

    This study deals with preparation and characterization of polymethylmetracrylate (PMMA) microcapsules containing n-octacosane as phase change material for thermal energy storage. The surface morphology, particle size and particle size distribution (PSD) were studied by scanning electron microscopy (SEM). The chemical characterization of PMMA/octacosane microcapsules was made by FT-IR spectroscopy method. Thermal properties and thermal stability of microencapsulated octacosane were determined using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). The melting and freezing temperatures and the latent heats of the microencapsulated octacosane as PCM were measured as 50.6 and 53.2 C, 86.4 and -88.5 J/g, respectively, by DSC analysis. TGA analysis indicated that the microencapsulated octacosane degrade in two steps and had good chemical stability. Thermal cycling test shows that the microcapsules have good thermal reliability with respect to the accelerated thermal cycling. Based on the results, it can be considered that the microencapsulated octacosane have good energy storage potential. (author)

  20. 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

  1. The monostandard method in thermal neutron activation analysis of geological, biological and environmental materials

    International Nuclear Information System (INIS)

    Alian, A.; Djingova, R.G.; Kroener, B.; Sansoni, B.

    1984-01-01

    A simple method is described for instrumental multielement thermal neutron activation analysis using a monostandard. For geological and air dust samples, iron is used as a comparator, while sodium has advantages for biological materials. To test the capabilities of this method, the values of the effective cross sections of the 23 elements determined were evaluated in a reactor site with an almost pure thermal neutron flux of about 9x10 12 nxcm -2 xs -1 and an epithermal neutron contribution of less than 0.03%. The values obtained were found to agree mostly well with the best literature values of thermal neutron cross sections. The results of an analysis by activation in the same site agree well with the relative method using multielement standards and for several standard reference materials with certified element contents. A comparison of the element contents obtained by the monostandard and relative methods together with corresponding precisions and accuracies is given. (orig.) [de

  2. A Negative Thermal Expansion Material of ZrMgMo3O12

    International Nuclear Information System (INIS)

    Song Wen-Bo; Liang Er-Jun; Liu Xian-Sheng; Li Zhi-Yuan; Yuan Bao-He; Wang Jun-Qiao

    2013-01-01

    A material with the formula ZrMgMo 3 O 12 having negative thermal expansion is presented and characterized. It is shown that ZrMgMo 3 O 12 crystallizes in an orthorhombic symmetry with space group Pnma(62) or Pna2 1 (33) and exhibits negative thermal expansion in a large temperature range (α l = −3.8 × 10 −6 K −1 from 300K to 1000K by x-ray diffraction and α l = −3.73 × 10 −6 K −1 from 295K to 775K by dilatometer). ZrMgMo 3 O 12 remains the orthorhombic structure without phase transition or decomposition at least from 123K to 1200K and is not hygroscopic. These properties make it an excellent material with negative thermal expansion for a variety of applications

  3. Thermal effects of variable material properties and metamorphic reactions in a three-component subducting slab

    DEFF Research Database (Denmark)

    Chemia, Zurab; Dolejš, David; Steinle-Neumann, Gerd

    2015-01-01

    We explore the effects of variable material properties, phase transformations, and metamorphic devolatilization reactions on the thermal structure of a subducting slab using thermodynamic phase equilibrium calculations combined with a thermal evolution model. The subducting slab is divided...... into three layers consisting of oceanic sediments, altered oceanic crust, and partially serpentinized or anhydrous harzburgite. Solid-fluid equilibria and material properties are computed for each layer individually to illustrate distinct thermal consequences when chemical and mechanical homogenization...... indicate that subducting sediments and oceanic crust warm by 40 and 70°C, respectively, before the effect of wedge convection and heating is encountered at 1.7 GPa. Retention of fluid in the slab pore space plays a negligible role in oceanic crust and serpentinized peridotites. By contrast, the large...

  4. Thermal Peak Management Using Organic Phase Change Materials for Latent Heat Storage in Electronic Applications

    Science.gov (United States)

    Maxa, Jacob; Novikov, Andrej; Nowottnick, Mathias

    2017-01-01

    Modern high power electronics devices consists of a large amount of integrated circuits for switching and supply applications. Beside the benefits, the technology exhibits the problem of an ever increasing power density. Nowadays, heat sinks that are directly mounted on a device, are used to reduce the on-chip temperature and dissipate the thermal energy to the environment. This paper presents a concept of a composite coating for electronic components on printed circuit boards or electronic assemblies that is able to buffer a certain amount of thermal energy, dissipated from a device. The idea is to suppress temperature peaks in electronic components during load peaks or electronic shorts, which otherwise could damage or destroy the device, by using a phase change material to buffer the thermal energy. The phase change material coating could be directly applied on the chip package or the PCB using different mechanical retaining jigs.

  5. The Effect of Mechanical Load on the Thermal Conductivity of Building Materials

    Directory of Open Access Journals (Sweden)

    J. Toman

    2000-01-01

    Full Text Available The effect of mechanical load on the thermal conductivity of building materials in the design of envelope parts of building structures is studied. A typical building material is chosen in the practical investigation of this effect, namely the cement mortar. It is concluded that in the range of hygroscopic moisture content, lower levels of mechanical load, typically up to 90 % of compressive strength (CS, are not dangerous from the point of view of worsening the designed thermal properties, but in the overhygroscopic region, the load as low as 57 % of CS may be dangerous. The higher levels of loading are found to be always significant because they lead to marked increase of thermal conductivity which is always a negative information for a building designer.

  6. Thermal Peak Management Using Organic Phase Change Materials for Latent Heat Storage in Electronic Applications

    Directory of Open Access Journals (Sweden)

    Jacob Maxa

    2017-12-01

    Full Text Available Modern high power electronics devices consists of a large amount of integrated circuits for switching and supply applications. Beside the benefits, the technology exhibits the problem of an ever increasing power density. Nowadays, heat sinks that are directly mounted on a device, are used to reduce the on-chip temperature and dissipate the thermal energy to the environment. This paper presents a concept of a composite coating for electronic components on printed circuit boards or electronic assemblies that is able to buffer a certain amount of thermal energy, dissipated from a device. The idea is to suppress temperature peaks in electronic components during load peaks or electronic shorts, which otherwise could damage or destroy the device, by using a phase change material to buffer the thermal energy. The phase change material coating could be directly applied on the chip package or the PCB using different mechanical retaining jigs.

  7. Thermal Stress Limit Rafting Migration of Seahorses: Prediction Based on Physiological and Behavioral Responses to Thermal Stress

    Science.gov (United States)

    Qin, G.; Li, C.; Lin, Q.

    2017-12-01

    Marine fish species escape from harmful environment by migration. Seahorses, with upright posture and low mobility, could migrate from unfavorable environment by rafting with their prehensile tail. The present study was designed to examine the tolerance of lined seahorse Hippocampus erectus to thermal stress and evaluate the effects of temperature on seahorse migration. The results figured that seahorses' tolerance to thermal stress was time dependent. Acute thermal stress (30°C) increased breathing rate and HSP genes expression significantly, but didn't affect seahorse feeding behavior. Chronic thermal treatment lead to persistent high expression of HSP genes, higher breathing rate, and decreasing feeding, and final higher mortality, suggesting that seahorse cannot adapt to thermal stress by acclimation. No significant negative effects were found in seahorse reproduction in response to chronic thermal stress. Given that seahorses make much slower migration by rafting on sea surface compared to other fishes, we suggest that thermal stress might limit seahorse migration range. and the influence might be magnified by global warming in future.

  8. Thermal characteristic investigation of eutectic composite fatty acid as heat storage material for solar heating and cooling application

    Science.gov (United States)

    Thaib, R.; Fauzi, H.; Ong, H. C.; Rizal, S.; Mahlia, T. M. I.; Riza, M.

    2018-03-01

    A composite phase change material (CPCM) of myristic acid/palmitic acid/sodium myristate (MA/PA/SM) and of myristic acid/palmitic acid/sodium laurate (MA/PA/SL) were impregnated with purified damar gum as called Shorea Javanica (SJ) to improve the thermal conductivity of CPCM. The thermal properties, thermal conductivity, and thermal stability of both CPCM have investigated by using a Differential Scanning Calorimetry (DSC) thermal analysis, hot disc thermal conductivity analyzer, and Simultaneous Thermal Analyzer (STA), simultaneously. However, a chemical compatibility between both fatty acid eutectic mixtures and SJ in composite mixtures measured by Fourier Transform Infra-Red (FT-IR) spectrophotometer. The results were obtained that the thermal conductivity of MA/PA/SM/SJ and MA/PA/SL/SJ eutectic composite phase change material (CPCM) were improved by addition 3 wt.% and 2 wt.% of Shorea javanica (SJ), respectively, without occur a significant change on thermal properties of CPCM. Moreover, the absorbance spectrum of FT-IR shows the good compatibility of SJ with both MA/PA/SM and MA/PA/SL eutectic mixtures, the composite PCM also present good thermal performance and good thermal stability. Therefore, it can be noted that the purified Shorea Javanica proposed, the as high conductive material in this study was able to improve the thermal conductivity of eutectic PCM without any significant reduction on its thermo-physical and chemical properties and can be recommended as novelty composite phase change material for thermal energy storage application.

  9. Pyrolysis responses of kevlar/epoxy composite materials on laser irradiating

    Science.gov (United States)

    Liu, Wei-ping; Wei, Cheng-hua; Zhou, Meng-lian; Ma, Zhi-liang; Song, Ming-ying; Wu, Li-xiong

    2017-05-01

    The pyrolysis responses of kevlar/epoxy composite materials are valuable to study in a case of high temperature rising rate for its widely application. Distinguishing from the Thermal Gravimetric Analysis method, an apparatus is built to research the pyrolysis responses of kevlar/epoxy composite materials irradiated by laser in order to offer a high temperature rising rate of the sample. By deploying the apparatus, a near real-time gas pressure response can be obtained. The sample mass is weighted before laser irradiating and after an experiment finished. Then, the gas products molecular weight and the sample mass loss evolution are derived. It is found that the pressure and mass of the gas products increase with the laser power if it is less than 240W, while the molecular weight varies inversely. The variation tendency is confusing while the laser power is bigger than 240W. It needs more deeper investigations to bring it to light.

  10. Coupled Aeroheating and Ablative Thermal Response Simulation Tool

    Data.gov (United States)

    National Aeronautics and Space Administration — The thermal protection system (TPS) performance requirements for atmospheric entry vehicles on current and future NASA missions preclude the use of heritage reusable...

  11. 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%.

  12. The use of lipids as phase change materials for thermal energy storage

    Science.gov (United States)

    Phase change materials (PCMs) are substances capable of absorbing and releasing large 2 amounts of thermal energy (heat or cold) as latent heat over constant temperature as they 3 undergo a change in state of matter (phase transition), commonly, between solid and 4 liquid phases. Since the late 194...

  13. Plastic deformation tests on fragile materials using a thermal expansion machine

    International Nuclear Information System (INIS)

    Orozco, E.; Morales, A.; Mendoza, A.

    1991-01-01

    Applying an electrical current on an iron bar, a thermal expansion can be induced. We have taken advantage of this to deform fragile materials, in order to study their mechanical properties. In this paper we show some gels and high T c oxide superconductors (Author)

  14. Transient thermal stresses in multiple connected region exhibiting temperature dependence of material properties

    International Nuclear Information System (INIS)

    Sugano, Yoshihiro; Maekawa, Toshiya.

    1983-01-01

    The examples of the analysis of thermal stress in multiple connection regions such as heat exchangers, nuclear reactor cores, ingot cases and polygonal region with elliptic holes are not few, but the temperature dependence of material constants was neglected in these researches because of the difficulty of analysis though the industrial problems related to thermal stress are apt to occur in the condition of relatively large temperature gradient. Also, the analysis of heat conduction problems taking the temperature dependence of material constants into account was limited to one-dimensional problems for which Kirchhoff's transmission can be used. The purpose of this study is to derive the equation of condition which assures the one-value property of rotation and displacement, taking the temperature dependence of material constants into account, and to complete the formulation of the plane thermal stress problems in multiple connection regions by stress function method. Also the method of numerical analysis using difference method is shown to examine the effectiveness of various formulated equations and the effect of the temperature dependence of material constants on temperature and thermal stress. The example of numerical calculation on a thin rectangular plate with a rectangular hole is shown. (Kako, I.)

  15. Hysteresis in magnetic materials: the role of structural disorder, thermal relaxation, and dynamic effects

    International Nuclear Information System (INIS)

    Bertotti, G.; Basso, V.; Beatrice, C.; LoBue, M.; Magni, A.; Tiberto, P.

    2001-01-01

    An overview is given of the present understanding of hysteresis phenomena in magnetic materials. The problem is addressed from three approximate viewpoints: the connection between rate-independent hysteresis and micromagnetics; the modifications brought into this picture by thermal relaxation effects; the role of rate-dependent magnetization mechanisms, like eddy-current-damped domain wall motion

  16. Thermally Self-Healing Polymeric Materials : The Next Step to Recycling Thermoset Polymers?

    NARCIS (Netherlands)

    Zhang, Youchun; Broekhuis, Antonius A.; Picchioni, Francesco

    2009-01-01

    We developed thermally self-healing polymeric materials on the basis of furan-functionalized, alternating thermosetting polyketones (PK-furan) and bis-maleimide by using the Diels-Alder (DA) and Retro-Diels-Alder (RDA) reaction sequence. PK-furan can be easily obtained under mild conditions by the

  17. Do encapsulated heat storage materials really retain their original thermal properties?

    Science.gov (United States)

    Chaiyasat, Preeyaporn; Noppalit, Sayrung; Okubo, Masayoshi; Chaiyasat, Amorn

    2015-01-14

    The encapsulation of Rubitherm®27 (RT27), which is one of the most common commercially supplied heat storage materials, by polystyrene (PS), polydivinyl benzene (PDVB) and polymethyl methacrylate (PMMA) was carried out using conventional radical microsuspension polymerization. The products were purified to remove free RT27 and free polymer particles without RT27. In the cases of PS and PDVB microcapsules, the latent heats of melting and crystallization for RT27 ( and , J/g-RT27) were clearly decreased by the encapsulation. On the other hand, those of the PMMA microcapsules were the same as pure RT27. A supercooling phenomenon was observed not only for PS and PDVB but also for the PMMA microcapsules. These results indicate that the thermal properties of the heat storage materials encapsulated depend on the type of polymer shells, i.e., encapsulation by polymer shell changes the thermal properties of RT27. This is quite different from the idea of other groups in the world, in which they discussed the thermal properties based on the ΔHm and ΔHc values expressed in J/g-capsule, assuming that the thermal properties of the heat storage materials are not changed by the encapsulation. Hereafter, this report should raise an alarm concerning the "wrong" common knowledge behind developing the encapsulation technology of heat storage materials.

  18. GCD TechPort Data Sheets Thermal Protection System Materials (TPSM) Project

    Science.gov (United States)

    Chinnapongse, Ronald L.

    2014-01-01

    The Thermal Protection System Materials (TPSM) Project consists of three distinct project elements: the 3-Dimensional Multifunctional Ablative Thermal Protection System (3D MAT) project element; the Conformal Ablative Thermal Protection System (CA-TPS) project element; and the Heatshield for Extreme Entry Environment Technology (HEEET) project element. 3D MAT seeks to design, develop and deliver a game changing material solution based on 3-dimensional weaving and resin infusion approach for manufacturing a material that can function as a robust structure as well as a thermal protection system. CA-TPS seeks to develop and deliver a conformal ablative material designed to be efficient and capable of withstanding peak heat flux up to 500 W/ sq cm, peak pressure up to 0.4 atm, and shear up to 500 Pa. HEEET is developing a new ablative TPS that takes advantage of state-of-the-art 3D weaving technologies and traditional manufacturing processes to infuse woven preforms with a resin, machine them to shape, and assemble them as a tiled solution on the entry vehicle substructure or heatshield.

  19. Recent Patents on Nano-Enhanced Materials for Use in Thermal Energy Storage (TES).

    Science.gov (United States)

    Ferrer, Gerard; Barreneche, Camila; Solé, Aran; Juliá, José Enrique; Cabeza, Luisa F

    2017-07-10

    Thermal energy storage (TES) systems using phase change materials (PCM) have been lately studied and are presented as one of the key solutions for the implementation of renewable energies. These systems take advantage of the latent heat of phase change of PCM during their melting/ solidification processes to store or release heat depending on the needs and availability. Low thermal conductivity and latent heat are the main disadvantages of organic PCM, while corrosion, subcooling and thermal stability are the prime problems that inorganic PCM present. Nanotechnology can be used to overcome these drawbacks. Nano-enhanced PCM are obtained by the dispersion of nanoparticles in the base material and thermal properties such as thermal conductivity, viscosity and specific heat capacity, within others, can be enhanced. This paper presents a review of the patents regarding the obtaining of nano-enhanced materials for thermal energy storage (TES) in order to realize the development nanotechnologies have gained in the TES field. Patents regarding the synthesis methods to obtain nano-enhanced phase materials (NEPCM) and TES systems using NEPCM have been found and are presented in the paper. The few existing number of patents found is a clear indicator of the recent and thus low development nanotechnology has in the TES field so far. Nevertheless, the results obtained with the reviewed inventions already show the big potential that nanotechnology has in TES and denote a more than probable expansion of its use in the next years. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

  20. SiC-dopped MCM-41 materials with enhanced thermal and hydrothermal stabilities

    International Nuclear Information System (INIS)

    Wang, Yingyong; Jin, Guoqiang; Tong, Xili; Guo, Xiangyun

    2011-01-01

    Graphical abstract: Novel SiC-dopped MCM-41 materials were synthesized by adding silicon carbide suspension in the molecular sieve precursor solvent followed by in situ hydrothermal synthesis. The dopped materials have a wormhole-like mesoporous structure and exhibit enhanced thermal and hydrothermal stabilities. Highlights: → SiC-dopped MCM-41 was synthesized by in situ hydrothermal synthesis of molecular sieve precursor combined with SiC. → The dopped MCM-41 materials show a wormhole-like mesoporous structure. → The thermal stability of the dopped materials have an increment of almost 100 o C compared with the pure MCM-41. → The hydrothermal stability of the dopped materials is also better than that of the pure MCM-41. -- Abstract: SiC-dopped MCM-41 mesoporous materials were synthesized by the in situ hydrothermal synthesis, in which a small amount of SiC was added in the precursor solvent of molecular sieve before the hydrothermal treatment. The materials were characterized by X-ray diffraction, transmission electron microscopy, X-ray photoelectron spectroscopy, N 2 physical adsorption and thermogravimetric analysis, respectively. The results show that the thermal and hydrothermal stabilities of MCM-41 materials can be improved obviously by incorporating a small amount of SiC. The structure collapse temperature of SiC-dopped MCM-41 materials is 100 o C higher than that of pure MCM-41 according to the differential scanning calorimetry analysis. Hydrothermal treatment experiments also show that the pure MCM-41 will losses it's ordered mesoporous structure in boiling water for 24 h while the SiC-dopped MCM-41 materials still keep partial porous structure.