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Sample records for aerogel thermal insulation

  1. Hybrid Multifoil Aerogel Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeffrey; Paik, Jong-Ah; Jones, Steven; Nesmith, Bill

    2008-01-01

    This innovation blends the merits of multifoil insulation (MFI) with aerogel-based insulation to develop a highly versatile, ultra-low thermally conductive material called hybrid multifoil aerogel thermal insulation (HyMATI). The density of the opacified aerogel is 240 mg/cm3 and has thermal conductivity in the 20 mW/mK range in high vacuum and 25 mW/mK in 1 atmosphere of gas (such as argon) up to 800 C. It is stable up to 1,000 C. This is equal to commercially available high-temperature thermal insulation. The thermal conductivity of the aerogel is 36 percent lower compared to several commercially available insulations when tested in 1 atmosphere of argon gas up to 800 C.

  2. Improved Aerogel Vacuum Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Ruemmele, Warren P.; Bue, Grant C.

    2009-01-01

    An improved design concept for aerogel vacuum thermal-insulation panels calls for multiple layers of aerogel sandwiched between layers of aluminized Mylar (or equivalent) poly(ethylene terephthalate), as depicted in the figure. This concept is applicable to both the rigid (brick) form and the flexible (blanket) form of aerogel vacuum thermal-insulation panels. Heretofore, the fabrication of a typical aerogel vacuum insulating panel has involved encapsulation of a single layer of aerogel in poly(ethylene terephthalate) and pumping of gases out of the aerogel-filled volume. A multilayer panel according to the improved design concept is fabricated in basically the same way: Multiple alternating layers of aerogel and aluminized poly(ethylene terephthalate) are assembled, then encapsulated in an outer layer of poly(ethylene terephthalate), and then the volume containing the multilayer structure is evacuated as in the single-layer case. The multilayer concept makes it possible to reduce effective thermal conductivity of a panel below that of a comparable single-layer panel, without adding weight or incurring other performance penalties. Implementation of the multilayer concept is simple and relatively inexpensive, involving only a few additional fabrication steps to assemble the multiple layers prior to evacuation. For a panel of the blanket type, the multilayer concept, affords the additional advantage of reduced stiffness.

  3. Aerogels for Thermal Insulation of Thermoelectric Devices

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeffrey; Fleurial, Jean-Pierre; Snyder, Jeffrey; Jones, Steven; Caillat, Thierry

    2006-01-01

    Silica aerogels have been shown to be attractive for use as thermal-insulation materials for thermoelectric devices. It is desirable to thermally insulate the legs of thermoelectric devices to suppress lateral heat leaks that degrade thermal efficiency. Aerogels offer not only high thermal- insulation effectiveness, but also a combination of other properties that are especially advantageous in thermoelectric- device applications. Aerogels are synthesized by means of sol-gel chemistry, which is ideal for casting insulation into place. As the scale of the devices to be insulated decreases, the castability from liquid solutions becomes increasingly advantageous: By virtue of castability, aerogel insulation can be made to encapsulate devices having any size from macroscopic down to nanoscopic and possibly having complex, three-dimensional shapes. Castable aerogels can permeate voids having characteristic dimensions as small as nanometers. Hence, practically all the void space surrounding the legs of thermoelectric devices could be filled with aerogel insulation, making the insulation highly effective. Because aerogels have the lowest densities of any known solid materials, they would add very little mass to the encapsulated devices. The thermal-conductivity values of aerogels are among the lowest reported for any material, even after taking account of the contributions of convection and radiation (in addition to true thermal conduction) to overall effective thermal conductivities. Even in ambient air, the contribution of convection to effective overall thermal conductivity of an aerogel is extremely low because of the highly tortuous nature of the flow paths through the porous aerogel structure. For applications that involve operating temperatures high enough to give rise to significant amounts of infrared radiation, opacifiers could be added to aerogels to reduce the radiative contributions to overall effective thermal conductivities. One example of an opacifier is

  4. Aerogel Beads as Cryogenic Thermal Insulation System

    NASA Technical Reports Server (NTRS)

    Fesmire, J. E.; Augustynowicz, S. D.; Rouanet, S.; Thompson, Karen (Technical Monitor)

    2001-01-01

    An investigation of the use of aerogel beads as thermal insulation for cryogenic applications was conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Steady-state liquid nitrogen boiloff methods were used to characterize the thermal performance of aerogel beads in comparison with conventional insulation products such as perlite powder and multilayer insulation (MLI). Aerogel beads produced by Cabot Corporation have a bulk density below 100 kilograms per cubic meter (kg/cubic m) and a mean particle diameter of 1 millimeter (mm). The apparent thermal conductivity values of the bulk material have been determined under steady-state conditions at boundary temperatures of approximately 293 and 77 kelvin (K) and at various cold vacuum pressures (CVP). Vacuum levels ranged from 10(exp -5) torr to 760 torr. All test articles were made in a cylindrical configuration with a typical insulation thickness of 25 mm. Temperature profiles through the thickness of the test specimens were also measured. The results showed the performance of the aerogel beads was significantly better than the conventional materials in both soft-vacuum (1 to 10 torr) and no-vacuum (760 torr) ranges. Opacified aerogel beads performed better than perlite powder under high-vacuum conditions. Further studies for material optimization and system application are in progress.

  5. Aerogel beads as cryogenic thermal insulation system

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Augustynowicz, S. D.; Rouanet, S.

    2002-05-01

    An investigation of the use of aerogel beads as thermal insulation for cryogenic applications was conducted at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Steady-state liquid nitrogen boiloff methods were used to characterize the thermal performance of aerogel beads in comparison with conventional insulation products such as perlite powder and multilayer insulation (MLI). Aerogel beads produced by Cabot Corporation have a bulk density below 100 kilograms per cubic meter (kg/m3) and a mean particle diameter of 1 millimeter (mm). The apparent thermal conductivity values of the bulk material have been determined under steady-state conditions at boundary temperatures of approximately 293 and 77 kelvin (K) and at various cold vacuum pressures (CVP). Vacuum levels ranged from 10-5 torr to 760 torr. All test articles were made in a cylindrical configuration with a typical insulation thickness of 25 mm. Temperature profiles through the thickness of the test specimens were also measured. The results showed the performance of the aerogel beads was significantly better than the conventional materials in both soft-vacuum (1 to 10 torr) and no-vacuum (760 torr) ranges. Opacified aerogel beads performed better than perlite powder under high-vacuum conditions. Further studies for material optimization and system application are in progress.

  6. Thermal Performance Testing of Order Dependancy of Aerogels Multilayered Insulation

    NASA Technical Reports Server (NTRS)

    Johnson, Wesley L.; Fesmire, James E.; Demko, J. A.

    2009-01-01

    Robust multilayer insulation systems have long been a goal of many research projects. Such insulation systems must provide some degree of structural support and also mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel composite blankets can be the best insulation materials in ambient pressure environments; in high vacuum, the thermal performance of aerogel improves by about one order of magnitude. Standard multilayer insulation (MU) is typically 50% worse at ambient pressure and at soft vacuum, but as much as two or three orders of magnitude better at high vacuum. Different combinations of aerogel and multilayer insulation systems have been tested at Cryogenics Test Laboratory of NASA Kennedy Space Center. Analysis performed at Oak Ridge National Laboratory showed an importance to the relative location of the MU and aerogel blankets. Apparent thermal conductivity testing under cryogenic-vacuum conditions was performed to verify the analytical conclusion. Tests results are shown to be in agreement with the analysis which indicated that the best performance is obtained with aerogel layers located in the middle of the blanket insulation system.

  7. Low-Density, Aerogel-Filled Thermal-Insulation Tiles

    NASA Technical Reports Server (NTRS)

    Santos, Maryann; Heng, Vann; Barney, Andrea; Oka, Kris; Droege, Michael

    2005-01-01

    Aerogel fillings have been investigated in a continuing effort to develop low-density thermal-insulation tiles that, relative to prior such tiles, have greater dimensional stability (especially less shrinkage), equal or lower thermal conductivity, and greater strength and durability. In preparation for laboratory tests of dimensional and thermal stability, prototypes of aerogel-filled versions of recently developed low-density tiles have been fabricated by impregnating such tiles to various depths with aerogel formations ranging in density from 1.5 to 5.6 lb/ft3 (about 53 to 200 kg/cu m). Results available at the time of reporting the information for this article showed that the thermal-insulation properties of the partially or fully aerogel- impregnated tiles were equivalent or superior to those of the corresponding non-impregnated tiles and that the partially impregnated tiles exhibited minimal (<1.5 percent) shrinkage after multiple exposures at a temperature of 2,300 F (1,260 C). Latest developments have shown that tiles containing aerogels at the higher end of the density range are stable after multiple exposures at the said temperature.

  8. Polyimide-Foam/Aerogel Composites for Thermal Insulation

    NASA Technical Reports Server (NTRS)

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

    2009-01-01

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

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

    NASA Technical Reports Server (NTRS)

    Ou, Danny; Trifu, Roxana; Caggiano, Gregory

    2013-01-01

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

  10. Thermal Performance Of Space Suit Elements With Aerogel Insulation For Moon And Mars Exploration

    NASA Technical Reports Server (NTRS)

    Tang, Henry H.; Orndoff, Evelyne S.; Trevino, Luis A.

    2006-01-01

    Flexible fiber-reinforced aerogel composites were studied for use as insulation materials of a future space suit for Moon and Mars exploration. High flexibility and good thermal insulation properties of fiber-reinforced silica aerogel composites at both high and low vacuum conditions make it a promising insulation candidate for the space suit application. This paper first presents the results of a durability (mechanical cycling) study of these aerogels composites in the context of retaining their thermal performance. The study shows that some of these Aerogels materials retained most of their insulation performance after up to 250,000 cycles of mechanical flex cycling. This paper also examines the problem of integrating these flexible aerogel composites into the current space suit elements. Thermal conductivity evaluations are proposed for different types of aerogels space suit elements to identify the lay-up concept that may have the best overall thermal performance for both Moon and Mars environments. Potential solutions in mitigating the silica dusting issue related to the application of these aerogels materials for the space suit elements are also discussed.

  11. Silicon Oxycarbide Aerogels for High-Temperature Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Evans, Owen; Rhine, Wendell; Coutinho, Decio

    2010-01-01

    This work has shown that the use of SOC-A35 leads to aerogel materials containing a significant concentration of carbidic species and limited amorphous free carbon. Substitution of the divalent oxide species in silica with tetravalent carbidic carbon has directly led to materials that exhibit increased network viscosity, reduced sintering, and limited densification. The SiOC aerogels produced in this work have the highest carbide content of any dense or porous SiOC glass reported in the literature at that time, and exhibit tremendous long-term thermal stability.

  12. "Flexible aerogel as a superior thermal insulation for high temperature superconductor cable applications"

    SciTech Connect

    White, Shannon O.; Demko, Jonathan A; Tomich, A.

    2010-01-01

    High temperature superconducting (HTS) cables are an advanced technology that can both strengthen and improve the national electrical distribution infrastructure. HTS cables require sufficient cooling to overcome inherent low temperature heat loading. Heat loads are minimized by the use of cryogenic envelopes or cryostats. Cryostats require improvement in efficiency, reliability, and cost reduction to meet the demanding needs of HTS conductors (1G and 2G wires). Aspen Aerogels has developed a compression resistant aerogel thermal insulation package to replace compression sensitive multi-layer insulation (MLI), the incumbent thermal insulation, in flexible cryostats for HTS cables. Oak Ridge National Laboratory tested a prototype aerogel package in a lab-scale pipe apparatus to measure the rate of heat invasion. The lab-scale pipe test results of the aerogel solution will be presented and directly compared to MLI. A compatibility assessment of the aerogel material with HTS system components will also be presented. The aerogel thermal insulation solution presented will meet the demanding needs of HTS cables.

  13. Foam/Aerogel Composite Materials for Thermal and Acoustic Insulation and Cryogen Storage

    NASA Technical Reports Server (NTRS)

    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. Foam/aerogel composite materials for thermal and acoustic insulation and cryogen storage

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Weiser, Erik S. (Inventor); Sass, Jared P. (Inventor)

    2010-01-01

    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.

  15. Multi-scale cellulose based new bio-aerogel composites with thermal super-insulating and tunable mechanical properties.

    PubMed

    Seantier, Bastien; Bendahou, Dounia; Bendahou, Abdelkader; Grohens, Yves; Kaddami, Hamid

    2016-03-15

    Bio-composite aerogels based on bleached cellulose fibers (BCF) and cellulose nanoparticles having various morphological and physico-chemical characteristics are prepared by a freeze-drying technique and characterized. The various composite aerogels obtained were compared to a BCF aerogel used as the reference. Severe changes in the material morphology were observed by SEM and AFM due to a variation of the cellulose nanoparticle properties such as the aspect ratio, the crystalline index and the surface charge density. BCF fibers form a 3D network and they are surrounded by the cellulose nanoparticle thin films inducing a significant reduction of the size of the pores in comparison with a neat BCF based aerogel. BET analyses confirm the appearance of a new organization structure with pores of nanometric sizes. As a consequence, a decrease of the thermal conductivities is observed from 28mWm(-1)K(-1) (BCF aerogel) to 23mWm(-1)K(-1) (bio-composite aerogel), which is below the air conductivity (25mWm(-1)K(-1)). This improvement of the insulation properties for composite materials is more pronounced for aerogels based on cellulose nanoparticles having a low crystalline index and high surface charge (NFC-2h). The significant improvement of their insulation properties allows the bio-composite aerogels to enter the super-insulating materials family. The characteristics of cellulose nanoparticles also influence the mechanical properties of the bio-composite aerogels. A significant improvement of the mechanical properties under compression is obtained by self-organization, yielding a multi-scale architecture of the cellulose nanoparticles in the bio-composite aerogels. In this case, the mechanical property is more dependent on the morphology of the composite aerogel rather than the intrinsic characteristics of the cellulose nanoparticles. PMID:26794770

  16. Cryogenic Thermal Performance Testing of Bulk-Fill and Aerogel Insulation Materials

    NASA Technical Reports Server (NTRS)

    Scholtens, B. E.; Fesmire, J. E.; Sass, J. P.; Augustynowicz, S. D.; Heckle, K. W.

    2007-01-01

    The research testing and demonstration of new bulk-fill materials for cryogenic thermal insulation systems was performed by the Cryogenics Test Laboratory at NASA Kennedy Space Center. Thermal conductivity testing under actual-use cryogenic conditions is a key to understanding the total system performance encompassing engineering, economics, and materials factors. A number of bulk fill insulation materials, including aerogel beads, glass bubbles, and perlite powder, were tested using a new cylindrical cryostat. Boundary temperatures for the liquid nitrogen boil-off method were 293 K and 78 K. Tests were performed as a function of cold vacuum pressure from high vacuum to no vacuum conditions. Results are compared with other complementary test methods in the range of 300 K to 20 K. Various testing techniques are shown to be required to obtain a complete understanding of the operating performance of a material and to provide data for answers to design engineering questions.

  17. Cryogenic Thermal Performance Testing of Bulk-Fill and Aerogel Insulation Materials

    NASA Astrophysics Data System (ADS)

    Scholtens, B. E.; Fesmire, J. E.; Sass, J. P.; Augustynowicz, S. D.; Heckle, K. W.

    2008-03-01

    Thermal conductivity testing under actual-use conditions is a key to understanding how cryogenic thermal insulation systems perform in regard to engineering, economics, and materials factors. The Cryogenics Test Laboratory at NASA's Kennedy Space Center tested a number of bulk-fill insulation materials, including aerogel beads, glass bubbles, and perlite powder, using a new cylindrical cryostat. Boundary temperatures for the liquid nitrogen boiloff method were 78 K and 293 K. Tests were performed as a function of cold vacuum pressure under conditions ranging from high vacuum to no vacuum. Results were compared with those from complementary test methods in the range of 20 K to 300 K. Various testing techniques are required to completely understand the operating performance of a material and to provide data for answers to design engineering questions.

  18. Nonflammable, Hydrophobic Aerogel Composites for Insulation

    NASA Technical Reports Server (NTRS)

    Redouane, Begag

    2005-01-01

    Aerogel composites that are both nonflammable and hydrophobic have been developed for use as lightweight thermal- insulation materials for cryogenic systems. Aerogels are well known in the industry for their effectiveness as thermal insulators under cryogenic conditions, but the treatments used heretofore to render them hydrophobic also make them flammable. Nonflammability would make it safer to use aerogel insulation, especially in oxygen-rich environments and on cryogenic systems that contain liquid oxygen. A composite of this type is a silica aerogel reinforced with fibers. In comparison with unreinforced aerogels, the aerogel composite is about ten times as stiff and strong, better able to withstand handling, and more amenable to machining to required shapes. The composite can be made hydrophobic and nonflammable by appropriate design of a sol-gel process used to synthesize the aerogel component. In addition to very low thermal conductivity needed for insulation, aerogel composites of this type have been found to exhibit high resistance to moisture and nonflammability in oxygen-rich atmospheres: Samples floating on water for months gained no weight and showed no signs of deterioration. Samples were found to be nonflammable, even in pure oxygen at atmospheric pressure [14.7 psia (0.10 MPa)

  19. Aerogel Blanket Insulation Materials for Cryogenic Applications

    NASA Technical Reports Server (NTRS)

    Coffman, B. E.; Fesmire, J. E.; White, S.; Gould, G.; Augustynowicz, S.

    2009-01-01

    Aerogel blanket materials for use in thermal insulation systems are now commercially available and implemented by industry. Prototype aerogel blanket materials were presented at the Cryogenic Engineering Conference in 1997 and by 2004 had progressed to full commercial production by Aspen Aerogels. Today, this new technology material is providing superior energy efficiencies and enabling new design approaches for more cost effective cryogenic systems. Aerogel processing technology and methods are continuing to improve, offering a tailor-able array of product formulations for many different thermal and environmental requirements. Many different varieties and combinations of aerogel blankets have been characterized using insulation test cryostats at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Detailed thermal conductivity data for a select group of materials are presented for engineering use. Heat transfer evaluations for the entire vacuum pressure range, including ambient conditions, are given. Examples of current cryogenic applications of aerogel blanket insulation are also given. KEYWORDS: Cryogenic tanks, thermal insulation, composite materials, aerogel, thermal conductivity, liquid nitrogen boil-off

  20. Aerogels Insulate Against Extreme Temperatures

    NASA Technical Reports Server (NTRS)

    2010-01-01

    In 1992, NASA started to pursue the development of aerogel for cryogenic insulation. Kennedy Space Center awarded Small Business Innovation Research (SBIR) contracts to Aspen Systems Inc., of Marlborough, Massachusetts, that resulted in a new manufacturing process and a new flexible, durable, easy-to-use form of aerogel. Aspen Systems formed Aspen Aerogels Inc., in Northborough, Massachusetts, to market the product, and by 2009, the company had become the leading provider of aerogel in the United States, producing nearly 20 million square feet per year. With an array of commercial applications, the NASA-derived aerogel has most recently been applied to protect and insulate people s hands and feet.

  1. Thermal resistance and compressive strain of underwater aerogel syntactic foam hybrid insulation at atmospheric and elevated hydrostatic pressure

    NASA Astrophysics Data System (ADS)

    Bardy, Erik; Mollendorf, Joseph; Pendergast, David

    2006-05-01

    The purpose of this study was to present a new underwater thermal insulation designed for flexibility and high thermal resistance. The insulation was a hybrid composite of two constituents: syntactic foam and an insulating aerogel blanket. Methods for treating and combining the constituents into a hybrid insulation of several designs are presented. A final configuration was selected based on high thermal resistance and was tested for thermal resistance and compressive strain to a pressure of 1.2 MPa (107 msw, meters of sea water) for five continuous pressure cycles. The thermal resistance and compressive strain results were compared to foam neoprene and underwater pipeline insulation. It was found that the hybrid insulation has a thermal resistance significantly higher than both foam neoprene and underwater pipeline insulation at atmospheric and elevated hydrostatic pressures (1.2 MPa). The total thermal resistance of the hybrid insulation decreased 32% at 1.2 MPa and returned to its initial value upon decompression. It was concluded that the hybrid insulation, with modifications, could be used for wetsuit construction, shallow underwater pipeline insulation, or any underwater application where high thermal resistance, flexibility, and resistance to compression are desired.

  2. Thermal properties of organic and modified inorganic aerogels

    SciTech Connect

    Pekala, R.W.; Hrubesh, L.W.

    1992-08-01

    Aerogels are open-cell foams that have already been shown to be among the best thermal insulating solid materials known. Improvements in the thermal insulating properties of aerogels are possible by synthesizing new organic varieties, by using additives within existing aerogel matrix, and by optimizing their nanostructures. We discuss these approaches and give some examples of aerogels which demonstrate the improvements.

  3. Fibrous-Ceramic/Aerogel Composite Insulating Tiles

    NASA Technical Reports Server (NTRS)

    White, Susan M.; Rasky, Daniel J.

    2004-01-01

    Fibrous-ceramic/aerogel composite tiles have been invented to afford combinations of thermal-insulation and mechanical properties superior to those attainable by making tiles of fibrous ceramics alone or aerogels alone. These lightweight tiles can be tailored to a variety of applications that range from insulating cryogenic tanks to protecting spacecraft against re-entry heating. The advantages and disadvantages of fibrous ceramics and aerogels can be summarized as follows: Tiles made of ceramic fibers are known for mechanical strength, toughness, and machinability. Fibrous ceramic tiles are highly effective as thermal insulators in a vacuum. However, undesirably, the porosity of these materials makes them permeable by gases, so that in the presence of air or other gases, convection and gas-phase conduction contribute to the effective thermal conductivity of the tiles. Other disadvantages of the porosity and permeability of fibrous ceramic tiles arise because gases (e.g., water vapor or cryogenic gases) can condense in pores. This condensation contributes to weight, and in the case of cryogenic systems, the heat of condensation undesirably adds to the heat flowing to the objects that one seeks to keep cold. Moreover, there is a risk of explosion associated with vaporization of previously condensed gas upon reheating. Aerogels offer low permeability, low density, and low thermal conductivity, but are mechanically fragile. The basic idea of the present invention is to exploit the best features of fibrous ceramic tiles and aerogels. In a composite tile according to the invention, the fibrous ceramic serves as a matrix that mechanically supports the aerogel, while the aerogel serves as a low-conductivity, low-permeability filling that closes what would otherwise be the open pores of the fibrous ceramic. Because the aerogel eliminates or at least suppresses permeation by gas, gas-phase conduction, and convection, the thermal conductivity of such a composite even at

  4. Aerogel Insulation Systems for Space Launch Applications

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.

    2005-01-01

    New developments in materials science in the areas of solution gelation processes and nanotechnology have led to the recent commercial production of aerogels. Concurrent with these advancements has been the development of new approaches to cryogenic thermal insulation systems. For example, thermal and physical characterizations of aerogel beads under cryogenic-vacuum conditions have been performed at the Cryogenics Test Laboratory of the NASA Kennedy Space Center. Aerogel-based insulation system demonstrations have also been conducted to improve performance for space launch applications. Subscale cryopumping experiments show the thermal insulating ability of these fully breathable nanoporous materials. For a properly executed thermal insulation system, these breathable aerogel systems are shown to not cryopump beyond the initial cooldown and thermal stabilization phase. New applications are being developed to augment the thermal protection systems of space launch vehicles, including the Space Shuttle External Tank. These applications include a cold-boundary temperature of 90 K with an ambient air environment in which both weather and flight aerodynamics are important considerations. Another application is a nitrogen-purged environment with a cold-boundary temperature of 20 K where both initial cooldown and launch ascent profiles must be considered. Experimental results and considerations for these flight system applications are discussed.

  5. Comparative Investigation on Thermal Insulation of Polyurethane Composites Filled with Silica Aerogel and Hollow Silica Microsphere.

    PubMed

    Liu, Chunyuan; Kim, Jin Seuk; Kwon, Younghwan

    2016-02-01

    This paper presents a comparative study on thermal conductivity of PU composites containing open-cell nano-porous silica aerogel and closed-cell hollow silica microsphere, respectively. The thermal conductivity of PU composites is measured at 30 degrees C with transient hot bridge method. The insertion of polymer in pores of silica aerogel creates mixed interfaces, increasing the thermal conductivity of resulting composites. The measured thermal conductivity of PU composites filled with hollow silica microspheres is estimated using theoretical models, and is in good agreement with Felske model. It appears that the thermal conductivity of composites decreases with increasing the volume fraction (phi) when hollow silica microsphere (eta = 0.916) is used. PMID:27433652

  6. Cellulose as an adhesion agent for the synthesis of lignin aerogel with strong mechanical performance, Sound-absorption and thermal Insulation.

    PubMed

    Wang, Chao; Xiong, Ye; Fan, Bitao; Yao, Qiufang; Wang, Hanwei; Jin, Chunde; Sun, Qingfeng

    2016-01-01

    The lignin aerogels that are both high porosity and compressibility would have promising implications for bioengineering field to sound-adsorption and damping materials; however, creating this aerogel had a challenge to adhesive lignin. Here we reported cellulose as green adhesion agent to synthesize the aerogels with strong mechanical performance. Our approach-straightforwardly dissolved in ionic liquids and simply regenerated in the deionized water-causes assembly of micro-and nanoscale and even molecule level of cellulose and lignin. The resulting lignin aerogels exhibit Young's modulus up to 25.1 MPa, high-efficiency sound-adsorption and excellent thermal insulativity. The successful synthesis of this aerogels developed a path for lignin to an advanced utilization. PMID:27562532

  7. Aerogels Insulate Missions and Consumer Products

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Aspen Aerogels, of Northborough, Massachusetts, worked with NASA through an SBIR contract with Kennedy Space Center to develop a robust, flexible form of aerogel for cryogenic insulation for space shuttle launch applications. The company has since used the same manufacturing process developed under the SBIR award to expand its product offerings into the more commercial realms, making the naturally fragile aerogel available for the first time as a standard insulation that can be handled and installed just like standard insulation.

  8. Aerogel Insulation Applications for Liquid Hydrogen Launch Vehicle Tanks

    NASA Technical Reports Server (NTRS)

    Fesmire, J. E.; Sass, J.

    2007-01-01

    Aerogel based insulation systems for ambient pressure environments were developed for liquid hydrogen (LH2) tank applications. Solutions to thermal insulation problems were demonstrated for the Space Shuttle External Tank (ET) through extensive testing at the Cryogenics Test Laboratory. Demonstration testing was performed using a 1/10th scale ET LH2 intertank unit and liquid helium as the coolant to provide the 20 K cold boundary temperature. Cryopumping tests in the range of 20K were performed using both constant mass and constant pressure methods. Long-duration tests (up to 10 hours) showed that the nitrogen mass taken up inside the intertank is reduced by a factor of nearly three for the aerogel insulated case as compared to the un-insulated (bare metal flight configuration) case. Test results including thermal stabilization, heat transfer effectiveness, and cryopumping confirm that the aerogel system eliminates free liquid nitrogen within the intertank. Physisorption (or adsorption) of liquid nitrogen within the fine pore structure of aerogel materials was also investigated. Results of a mass uptake method show that the sorption ratio (liquid nitrogen to aerogel beads) is about 62 percent by volume. A novel liquid nitrogen production method of testing the liquid nitrogen physical adsorption capacity of aerogel beads was also performed to more closely approximate the actual launch vehicle cooldown and thermal stabilization effects within the aerogel material. The extraordinary insulating effectiveness of the aerogel material shows that cryopumping is not an open-cell mass transport issue but is strictly driven by thermal communication between warm and cold surfaces. The new aerogel insulation technology is useful to solve heat transfer problem areas and to augment existing thermal protection systems on launch vehicles. Examples are given and potential benefits for producing launch systems that are more reliable, robust, reusable, and efficient are outlined.

  9. Aerogel-Based Multilayer Insulation with Micrometeoroid Protection

    NASA Technical Reports Server (NTRS)

    Begag, Redouane; White, Shannon

    2013-01-01

    Ultra-low-density, highly hydrophobic, fiber-reinforced aerogel material integrated with MLI (aluminized Mylar reflectors and B4A Dacron separators) offers a highly effective insulation package by providing unsurpassed thermal performance and significant robustness, delivering substantial MMOD protection via the addition of a novel, durable, external aerogel layer. The hydrophobic nature of the aerogel is an important property for maintaining thermal performance if the material is exposed to the environment (i.e. rain, snow, etc.) during ground installations. The hybrid aerogel/MLI/MMOD solution affords an attractive alternative because it will perform thermally in the same range as MLI at all vacuum levels (including high vacuum), and offers significant protection from micrometeoroid damage. During this effort, the required low-density and resilient aerogel materials have been developed that are needed to optimize the thermal performance for space (high vacuum) cryotank applications. The proposed insulation/MMOD package is composed of two sections: a stack of interleaved aerogel layers and MLI intended for cryotank thermal insulation, and a 1.5- to 1-in. (.2.5- to 3.8- cm) thick aerogel layer (on top of the insulation portion) for MMOD protection. Learning that low-density aerogel cannot withstand the hypervelocity impact test conditions, the innovators decided during the course of the program to fabricate a high-density and strong material based on a cross-linked aerogel (X-aerogel; developed elsewhere by the innovators) for MMOD protection. This system has shown a very high compressive strength that is capable of withstanding high-impact tests if a proper configuration of the MMOD aerogel layer is used. It was learned that by stacking two X-aerogel layers [1.5-in. (.3.8-cm) thick] separated by an air gap, the system would be able to hold the threat at a speed of 5 km/s and gpass h the test. The first aerogel panel stopped the projectile from damaging the second

  10. Nanogel Aerogel as Load Bearing Insulation for Cryogenic Systems

    NASA Astrophysics Data System (ADS)

    Koravos, J. J.; Miller, T. M.; Fesmire, J. E.; Coffman, B. E.

    2010-04-01

    Load support structures in cryogenic storage, transport and processing systems are large contributors to the total heat leak of the system. Conventional insulation systems require the use of these support members in order to stabilize the process fluid enclosure and prevent degradation of insulation performance due to compression. Removal of these support structures would substantially improve system efficiency. Nanogel aerogel insulation performance is tested at vacuum pressures ranging from high vacuum to atmospheric pressure and under loads from loosely packed to greater than 10,000 Pa. Insulation performance is determined using boil-off calorimetry with liquid nitrogen as the latent heat recipient. Two properties of the aerogel insulation material suit it to act as a load bearing "structure" in a process vessel: (1) Ability to maintain thermal performance under load; (2) Elasticity when subjected to load. Results of testing provide positive preliminary indication that these properties allow Nanogel aerogel to effectively be used as a load bearing insulation in cryogenic systems.

  11. Analysis and Testing of Multilayer and Aerogel Insulation Configurations

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Demko, J. A.; Fesmire, J. E.

    2010-04-01

    Multilayer insulation systems that have robust operational characteristics have long been a goal of many research projects. Such thermal insulation systems may need to offer some degree of structural support and/or mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel-based composite blankets can be the best insulation materials in ambient pressure environments; in high vacuum, the thermal performance of aerogel improves by about one order of magnitude. Standard multilayer insulation (MLI) is typically 50% worse at ambient pressure and at soft vacuum, but as much as two or three orders of magnitude better at high vacuum. Different combinations of aerogel blanket and multilayer insulation materials have been tested at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Analysis performed at Oak Ridge National Laboratory showed an importance to the relative location of the MLI and aerogel blankets. Apparent thermal conductivity testing under cryogenic-vacuum conditions was performed to verify the analytical conclusion. Tests results are shown to be in agreement with the analysis which indicated that the best performance is obtained with aerogel layers located in the middle of the blanket insulation system.

  12. Analysis and testing of multilayer and aerogel insulation configurations

    SciTech Connect

    Johnson, W L; Demko, Jonathan A; Fesmire, J. E.

    2010-01-01

    Multilayer insulation systems that have robust operational characteristics have long been a goal of many research projects. Such thermal insulation systems may need to offer some degree of structural support and/or mechanical integrity during loss of vacuum scenarios while continuing to provide insulative value to the vessel. Aerogel-based composite blankets can be the best insulation materials in ambient pressure environments; in high vacuum, the thermal performance of aerogel improves by about one order of magnitude. Standard multilayer insulation (MLI) is typically 50% worse at ambient pressure and at soft vacuum, but as much as two or three orders of magnitude better at high vacuum. Different combinations of aerogel blanket and multilayer insulation materials have been tested at the Cryogenics Test Laboratory of NASA Kennedy Space Center. Analysis performed at Oak Ridge National Laboratory showed an importance to the relative location of the MLI and aerogel blankets. Apparent thermal conductivity testing under cryogenicvacuum conditions was performed to verify the analytical conclusion. Tests results are shown to be in agreement with the analysis which indicated that the best performance is obtained with aerogel layers located in the middle of the blanket insulation system.

  13. Aerogel Composites for Aerospace Thermal Protection

    NASA Technical Reports Server (NTRS)

    White, Susan

    2003-01-01

    Aerogel composites formed by infiltrating organic and/or inorganic aerogels into fiber matrix materials enable us to exploit the low thermal conductivity and low density of aerogels while maintaining the strength, structure and other useful properties of a porous fiber matrix. New materials for extreme heating ranges are needed to insulate future spacecraft against the extreme heat of planetary atmospheric entry, but the insulation mass must be minimized in order to maximize the payload. A reusable system passively insulates to survive heating unchanged for relatively low heating. Ablators, which sacrifice mass to control heating, are used to protect vehicles against more extreme heating for a single use thermal protection system (TPS). Aerogel composites were fabricated and tested for spacecraft thermal protection. The high-temperaturey high heat flux tests described in this paper were performed in NASA Ames arc-jet facilities to simulate spacecraft atmospheric entry, and include heating conditions predicted for the forebody and backshell of the Mars Science Lander (MSL) entry probe. The aerogel composites tested showed excellent thermal performance in the arc-jet tests, functioning both as reusuable insulation under lower heat fluxes, and as ablative aerogels under the extreme heating predicted for the MSL forebody.

  14. Aerogel-Based Insulation for Industrial Steam Distribution Systems

    SciTech Connect

    John Williams

    2011-03-30

    Thermal losses in industrial steam distribution systems account for 977 trillion Btu/year in the US, more than 1% of total domestic energy consumption. Aspen Aerogels worked with Department of Energy’s Industrial Technologies Program to specify, develop, scale-up, demonstrate, and deliver Pyrogel XT®, an aerogel-based pipe insulation, to market to reduce energy losses in industrial steam systems. The product developed has become Aspen’s best selling flexible aerogel blanket insulation and has led to over 60 new jobs. Additionally, this product has delivered more than ~0.7 TBTU of domestic energy savings to date, and could produce annual energy savings of 149 TBTU by 2030. Pyrogel XT’s commercial success has been driven by it’s 2-4X better thermal performance, improved durability, greater resistance to corrosion under insulation (CUI), and faster installation times than incumbent insulation materials.

  15. Thin Aerogel as a Spacer in Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Moroz, Nancy

    2015-01-01

    Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on rea-lworld tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

  16. Thin Aerogel as a Spacer in Multilayer Insulation

    NASA Technical Reports Server (NTRS)

    Moroz, Nancy

    2015-01-01

    Cryogenic fluid management is a critical technical area that is needed for future space exploration. A key challenge is the storability of liquid hydrogen (LH2), liquid methane (LCH4), and liquid oxygen (LOX) propellants for long-duration missions. The storage tanks must be well-insulated to prevent over-pressurization and venting, which can lead to unacceptable propellant losses for long-duration missions to Mars and beyond. Aspen Aerogels had validated the key process step to enable the fabrication of thin, low-density aerogel materials. The multilayer aerogel insulation (MLAI) system prototypes were prepared using sheets of aerogel materials with superior thermal performance exceeding current state-of-the-art insulation for space applications. The exceptional properties of this system include a new breakthrough in high-vacuum cryogenic thermal insulation, providing a durable material with excellent thermal performance at a reduced cost when compared to longstanding state-of-the-art multilayer insulation systems. During the Phase II project, further refinement and qualification/system-level testing of the MLAI system will be performed for use in cryogenic storage applications. Aspen has been in discussions with United Launch Alliance, LLC; NASA's Kennedy Space Center; and Yetispace, Inc., to test the MLAI system on real-world tanks such as Vibro-Acoustic Test Article (VATA) or the Cryogenic Orbital Testbed (CRYOTE).

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

    SciTech Connect

    Dr. Owen Evans

    2011-10-13

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

  18. Thermal insulator

    SciTech Connect

    Yamamoto, R.; Asada, Y.; Matsuo, Y.; Mikoda, M.

    1985-07-16

    A thermal insulator comprises an expanded resin body having embedded therein an evacuated powder insulation portion which consists of fine powder and a container of film-like plastics or a film-like composite of plastics and metal for enclosing the powder. The resin body has been expanded by a Freon gas as a blowing agent. Since a Freon gas has a larger molecular diameter than the constituent gases of air, it is less likely to permeate through the container than air. Thus present invention provides a novel composite insulator which fully utilizes the benefits of vacuum insulation without necessitating a strong and costly material for a vacuum container.

  19. Thermal Insulation

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Commercially known as Solimide, Temptronics, Inc.'s thermal insulation has application in such vehicles as aircraft, spacecraft and surface transportation systems (i.e. rapid transit cars, trains, buses, and ships) as acoustical treatment for door, wall, and ceiling panels, as a means of reducing vibrations, and as thermal insulation (also useful in industrial equipment). Product originated from research conducted by Johnson Space Center on advanced flame-resistant materials for minimizing fire hazard in the Shuttle and other flight vehicles.

  20. Monte Carlo Study on Carbon-Gradient-Doped Silica Aerogel Insulation.

    PubMed

    Zhao, Y; Tang, G H

    2015-04-01

    Silica aerogel is almost transparent for wavelengths below 8 µm where significant energy is transferred by thermal radiation. The radiative heat transfer can be restricted at high temperature if doped with carbon powder in silica aerogel. However, different particle sizes of carbon powder doping have different spectral extinction coefficients and the doped carbon powder will increase the solid conduction of silica aerogel. This paper presents a theoretical method for determining the optimal carbon doping in silica aerogel to minimize the energy transfer. Firstly we determine the optimal particle size by combining the spectral extinction coefficient with blackbody radiation and then evaluate the optimal doping amount between heat conduction and radiation. Secondly we develop the Monte Carlo numerical method to study radiative properties of carbon-gradient-doped silica aerogel to decrease the radiative heat transfer further. The results indicate that the carbon powder is able to block infrared radiation and thus improve the thermal insulating performance of silica aerogel effectively. PMID:26353574

  1. Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

    DOEpatents

    Ruffner, Judith A.; Bullington, Jeff A.; Clem, Paul G.; Warren, William L.; Brinker, C. Jeffrey; Tuttle, Bruce A.; Schwartz, Robert W.

    1999-01-01

    A monolithic infrared detector structure which allows integration of pyroelectric thin films atop low thermal conductivity aerogel thin films. The structure comprises, from bottom to top, a substrate, an aerogel insulating layer, a lower electrode, a pyroelectric layer, and an upper electrode layer capped by a blacking layer. The aerogel can offer thermal conductivity less than that of air, while providing a much stronger monolithic alternative to cantilevered or suspended air-gap structures for pyroelectric thin film pixel arrays. Pb(Zr.sub.0.4 Ti.sub.0.6)O.sub.3 thin films deposited on these structures displayed viable pyroelectric properties, while processed at 550.degree. C.

  2. Heat insulation performance, mechanics and hydrophobic modification of cellulose-SiO2 composite aerogels.

    PubMed

    Shi, Jianjun; Lu, Lingbin; Guo, Wantao; Zhang, Jingying; Cao, Yang

    2013-10-15

    Cellulose-SiO2 composite hydrogel was prepared by combining the NaOH/thiourea/H2O solvent system and the immersion method with controlling the hydrolysis-fasculation rate of tetraethyl orthosilicate (TEOS). The hydrophobic composite aerogels were obtained through the freeze-drying technology and the cold plasma modification technology. Composite SiO2 could obviously reduce the thermal conductivity of cellulose aerogel. The thermal conductivity could be as low as 0.026 W/(mK). The thermal insulation mechanism of the aerogel material was discussed. Composite SiO2 reduced hydrophilicity of cellulose aerogel, but environmental humidity had a significant influence on heat insulation performance. After hydrophobic modification using CCl4 as plasma was conducted, the surface of composite aerogel was changed from hydrophilic to hydrophobic and water contact angle was as high as 132°. The modified composite aerogel still kept good heat insulation performance. This work provided a foundation for the possibility of applying cellulose-SiO2 composite aerogel in the insulating material field. PMID:23987346

  3. Thin aerogel films for optical, thermal, acoustic, and electronic applications

    SciTech Connect

    Hrubesh, L.W.; Poco, J.F.

    1994-09-01

    Aerogels are a special class of continuously porous solid materials which are characterized by nanometer size particles and pores. Typically, aerogels are made using sol-gel chemistry to form a solvent filled, high porosity gel that is dried by removing the solvent without collapsing the tenuous solid phase. As bulk materials, aerogels are known to have many exceptional, and even some unique physical properties. Aerogels provide the highest thermal insulation and lowest dielectric constant of any other material known. However, some important applications require the aerogels in the form of thin films or sheets. For example, electronic applications require micrometer thin aerogel films bonded to a substrate, and others require thicker films, either on a substrate or as free standing sheets. Special methods are required to make aerogel thin films or sheets. In this paper, the authors discuss the special conditions needed to fabricate thin aerogel films and they describe methods to make films and thin sheets. They also give some specific applications for which aerogel films are being developed.

  4. Aerogels with 3D ordered nanofiber skeletons of liquid-crystalline nanocellulose derivatives as tough and transparent insulators.

    PubMed

    Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2014-09-22

    Aerogels of high porosity and with a large internal surface area exhibit outstanding performances as thermal, acoustic, or electrical insulators. However, most aerogels are mechanically brittle and optically opaque, and the structural and physical properties of aerogels strongly depend on their densities. The unfavorable characteristics of aerogels are intrinsic to their skeletal structures consisting of randomly interconnected spherical nanoparticles. A structurally new type of aerogel with a three-dimensionally ordered nanofiber skeleton of liquid-crystalline nanocellulose (LC-NCell) is now reported. This LC-NCell material is composed of mechanically strong, surface-carboxylated cellulose nanofibers dispersed in a nematic LC order. The LC-NCell aerogels are transparent and combine mechanical toughness and good insulation properties. These properties of the LC-NCell aerogels could also be readily controlled. PMID:24985785

  5. Study on Thermal Conductivities of Aromatic Polyimide Aerogels.

    PubMed

    Feng, Junzong; Wang, Xin; Jiang, Yonggang; Du, Dongxuan; Feng, Jian

    2016-05-25

    Polyimide aerogels for low density thermal insulation materials were produced by 4,4'-diaminodiphenyl ether and 3,3',4,4'-biphenyltetracarboxylic dianhydride, cross-linked with 1,3,5-triaminophenoxybenzene. The densities of obtained polyimide aerogels are between 0.081 and 0.141 g cm(-3), and the specific surface areas are between 288 and 322 m(2) g(-1). The thermal conductivities were measured by a Hot Disk thermal constant analyzer. The value of the measured thermal conductivity under carbon dioxide atmosphere is lower than that under nitrogen atmosphere. Under pressure of 5 Pa at -130 °C, the thermal conductivity is the lowest, which is 8.42 mW (m K)(-1). The polyimide aerogels have lower conductivity [30.80 mW (m K)(-1)], compared to the value for other organic foams (polyurethane foam, phenolic foam, and polystyrene foam) with similar apparent densities under ambient pressure at 25 °C. The results indicate that polyimide aerogel is an ideal insulation material for aerospace and other applications. PMID:27149155

  6. Prototype Aerogel Insulation for Melamine-Foam Substitute: Critical Space Station Express Rack Technology

    NASA Technical Reports Server (NTRS)

    Noever, David A.; Sibille, Laurent; Smith, David; Cronise, Raymond

    1998-01-01

    There is a current lack of environmentally acceptable foams to insulate Long-Duration Human Spaceflight Missions, including the experimental Express Rack for the Space Station. A recent 60-day manned test in a sealed chamber at Johnson Space Center (JSC) was nearly aborted, because of persistently high formaldehyde concentrations in the chamber. Subsequent investigation showed that the source was melamine foam (used extensively for acoustic insulation). The thermal and acoustic potential for melamine-foam substitutes is evaluated for scale-up to a silica-based foam and aerogel, which is environmentally benign for long duration space flight. These features will be discussed in reference to an aerogel prototype to: 1) assemble material strength data for various formulated aerogels, both silica and organic carbon aerogels; 2) assemble the aerogel into panels of mylar/vacuum-encapsulated rigid boards which can be molded in various shapes and rigidities; and 3) describe a process for space applications for formaldehyde-free, long duration thermal and acoustic insulators.

  7. Improvements of reinforced silica aerogel nanocomposites thermal properties for architecture applications.

    PubMed

    Saboktakin, Amin; Saboktakin, Mohammad Reza

    2015-01-01

    An 1,4-cis polybutadiene rubber/carboxymethyl starch (CMS)-based silica aerogel nanocomposites as a insulation material was developed that will provide superior thermal insulation properties, flexibility, toughness, durability of the parent polymer, yet with the low density and superior insulation properties associated with the aerogels. In this study, reinforced 1,4-cis polybutadiene-CMS-silica aerogel nanocomposites were prepared from a silica aerogel with a surface area 710 m(2) g(-1), a pore size of 25.3 nm and a pore volume of 4.7 cm(3) g(-1). The tensile properties and dynamic mechanical properties of 1,4-cis polybutadiene/CMS nanocomposites were systematically enhanced at low silica loading. Similar improvements in tensile modulus and strength have been observed for 1,4-cis polybutadiene/CMS mesoporous silica aerogel nanocomposites. PMID:25172161

  8. Thermal Insulation Strips Conserve Energy

    NASA Technical Reports Server (NTRS)

    2009-01-01

    Launching the space shuttle involves an interesting paradox: While the temperatures inside the shuttle s main engines climb higher than 6,000 F hot enough to boil iron for fuel, the engines use liquid hydrogen, the second coldest liquid on Earth after liquid helium. Maintained below 20 K (-423 F), the liquid hydrogen is contained in the shuttle s rust-colored external tank. The external tank also contains liquid oxygen (kept below a somewhat less chilly 90 K or -297 F) that combines with the hydrogen to create an explosive mixture that along with the shuttle s two, powdered aluminum-fueled solid rocket boosters allows the shuttle to escape Earth s gravity. The cryogenic temperatures of the main engines liquid fuel can cause ice, frost, or liquefied air to build up on the external tank and other parts of the numerous launch fueling systems, posing a possible debris risk when the ice breaks off during launch and causing difficulties in the transfer and control of these cryogenic liquid propellants. Keeping the fuel at the necessary ultra-cold temperatures while minimizing ice buildup and other safety hazards, as well as reducing the operational maintenance costs, has required NASA to explore innovative ways for providing superior thermal insulation systems. To address the challenge, the Agency turned to an insulating technology so effective that, even though it is mostly air, a thin sheet can prevent a blowtorch from igniting a match. Aerogels were invented in 1931 and demonstrate properties that make them the most extraordinary insulating materials known; a 1-inch-thick piece of aerogel provides the same insulation as layering 15 panes of glass with air pockets in between. Derived from silica, aluminum oxide, or carbon gels using a supercritical drying process - resulting in a composition of almost 99-percent air - aerogels are the world s lightest solid (among 15 other titles they hold in the Guinness World Records), can float indefinitely on water if treated to be

  9. Strong, Thermally Superinsulating Biopolymer-Silica Aerogel Hybrids by Cogelation of Silicic Acid with Pectin.

    PubMed

    Zhao, Shanyu; Malfait, Wim J; Demilecamps, Arnaud; Zhang, Yucheng; Brunner, Samuel; Huber, Lukas; Tingaut, Philippe; Rigacci, Arnaud; Budtova, Tatiana; Koebel, Matthias M

    2015-11-23

    Silica aerogels are excellent thermal insulators, but their brittle nature has prevented widespread application. To overcome these mechanical limitations, silica-biopolymer hybrids are a promising alternative. A one-pot process to monolithic, superinsulating pectin-silica hybrid aerogels is presented. Their structural and physical properties can be tuned by adjusting the gelation pH and pectin concentration. Hybrid aerogels made at pH 1.5 exhibit minimal dust release and vastly improved mechanical properties while remaining excellent thermal insulators. The change in the mechanical properties is directly linked to the observed "neck-free" nanoscale network structure with thicker struts. Such a design is superior to "neck-limited", classical inorganic aerogels. This new class of materials opens up new perspectives for novel silica-biopolymer nanocomposite aerogels. PMID:26447457

  10. Process for forming transparent aerogel insulating arrays

    DOEpatents

    Tewari, Param H.; Hunt, Arlon J.

    1986-01-01

    An improved supercritical drying process for forming transparent silica aerogel arrays is described. The process is of the type utilizing the steps of hydrolyzing and condensing aloxides to form alcogels. A subsequent step removes the alcohol to form aerogels. The improvement includes the additional step, after alcogels are formed, of substituting a solvent, such as CO.sub.2, for the alcohol in the alcogels, the solvent having a critical temperature less than the critical temperature of the alcohol. The resulting gels are dried at a supercritical temperature for the selected solvent, such as CO.sub.2, to thereby provide a transparent aerogel array within a substantially reduced (days-to-hours) time period. The supercritical drying occurs at about 40.degree. C. instead of at about 270.degree. C. The improved process provides increased yields of large scale, structurally sound arrays. The transparent aerogel array, formed in sheets or slabs, as made in accordance with the improved process, can replace the air gap within a double glazed window, for example, to provide a substantial reduction in heat transfer. The thus formed transparent aerogel arrays may also be utilized, for example, in windows of refrigerators and ovens, or in the walls and doors thereof or as the active material in detectors for analyzing high energy elementry particles or cosmic rays.

  11. Process for forming transparent aerogel insulating arrays

    DOEpatents

    Tewari, P.H.; Hunt, A.J.

    1985-09-04

    An improved supercritical drying process for forming transparent silica aerogel arrays is described. The process is of the type utilizing the steps of hydrolyzing and condensing aloxides to form alcogels. A subsequent step removes the alcohol to form aerogels. The improvement includes the additional step, after alcogels are formed, of substituting a solvent, such as CO/sub 2/, for the alcohol in the alcogels, the solvent having a critical temperature less than the critical temperature of the alcohol. The resulting gels are dried at a supercritical temperature for the selected solvent, such as CO/sub 2/, to thereby provide a transparent aerogel array within a substantially reduced (days-to-hours) time period. The supercritical drying occurs at about 40/sup 0/C instead of at about 270/sup 0/C. The improved process provides increased yields of large scale, structurally sound arrays. The transparent aerogel array, formed in sheets or slabs, as made in accordance with the improved process, can replace the air gap within a double glazed window, for example, to provide a substantial reduction in heat transfer. The thus formed transparent aerogel arrays may also be utilized, for example, in windows of refrigerators and ovens, or in the walls and doors thereof or as the active material in detectors for analyzing high energy elementary particles or cosmic rays.

  12. Multipurpose Thermal Insulation Test Apparatus

    NASA Technical Reports Server (NTRS)

    Fesmire, James E. (Inventor); Augustynowicz, Stanislaw D. (Inventor)

    2002-01-01

    A multi-purpose thermal insulation test apparatus is used for testing insulation materials, or other components. The test apparatus is a fluid boil-off calorimeter system for calibrated measurement of the apparent thermal conductivity (k-value) of a specimen material at a fixed vacuum level. The apparatus includes an inner vessel for receiving a fluid with a normal boiling point below ambient temperature, such as liquid nitrogen, enclosed within a vacuum chamber. A cold mass assembly, including the inner vessel and thermal guards, is suspended from the top of the vacuum chamber. Handling tools attach to the cold mass assembly for convenient manipulation of the assembly and for the installation or wrapping of insulation test materials. Liquid nitrogen is typically supplied to the inner vessel using a fill tube with funnel. A single port through the top of the vacuum chamber facilitates both filling and venting. Aerogel composite stacks with reflective films are fastened to the top and the bottom of the inner vessel as thermal guards. The comparative k-value of the insulation material is determined by measuring the boil-off flow rate of gas, the temperature differential across the insulation thickness, and the dimensions (length and diameters) of the test specimen.

  13. High Temperature Aerogels for Thermal Protection Systems

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Mbah, Godfrey C.

    2008-01-01

    High temperature aerogels in the Al2O3-SiO2 system are being investigated as possible constituents for lightweight integrated thermal protection system (TPS) designs for use in supersonic and hypersonic applications. Gels are synthesized from ethoxysilanes and AlCl3.6H2O, using an epoxide catalyst. The influence of Al:Si ratio, solvent, water to metal and water to alcohol ratios on aerogel composition, morphology, surface area, and pore size distribution were examined, and phase transformation on heat treatment characterized. Aerogels have been fabricated which maintain porous, fractal structures after brief exposures to 1000 C. Incorporation of nanofibers, infiltration of aerogels into SiC foams, use of polymers for crosslinking the aerogels, or combinations of these, offer potential for toughening and integration of TPS with composite structure. Woven fabric composites having Al2O3-SiO2 aerogels as a matrix also have been fabricated. Continuing work is focused on reduction in shrinkage and optimization of thermal and physical properties.

  14. Aerogel nanocomposite materials

    SciTech Connect

    Hunt, A.J.; Ayers, M.; Cao, W.

    1995-05-01

    Aerogels are porous, low density, nanostructured solids with many unusual properties including very low thermal conductivity, good transparency, high surface area, catalytic activity, and low sound velocity. This research is directed toward developing new nanocomposite aerogel materials for improved thermal insulation and several other applications. A major focus of the research has been to further increase the thermal resistance of silica aerogel by introducing infrared opacification agents into the aerogel to produce a superinsulating composite material. Opacified superinsulating aerogel permit a number of industrial applications for aerogel-based insulation. The primary benefits from this recently developed superinsulating composite aerogel insulation are: to extend the range of applications to higher temperatures, to provide a more compact insulation for space sensitive-applications, and to lower costs of aerogel by as much as 30%. Superinsulating aerogels can replace existing CFC-containing polyurethane in low temperature applications to reduce heat losses in piping, improve the thermal efficiency of refrigeration systems, and reduce energy losses in a variety of industrial applications. Enhanced aerogel insulation can also replace steam and process pipe insulation in higher temperature applications to substantially reduce energy losses and provide much more compact insulation.

  15. Design Tool for Cryogenic Thermal Insulation Systems

    SciTech Connect

    Demko, Jonathan A; Fesmire, J. E.; Augustynowicz, S. D.

    2008-01-01

    Thermal isolation of low-temperature systems from ambient environments is a constant issue faced by practitioners of cryogenics. For energy-efficient systems and processes to be realized, thermal insulation must be considered as an integrated system, not merely an add-on element. A design tool to determine the performance of insulation systems for comparative trade-off studies of different available material options was developed. The approach is to apply thermal analysis to standard shapes (plane walls, cylinders, spheres) that are relatively simple to characterize with a one-dimensional analytical or numerical model. The user describes the system hot and cold boundary geometry and the operating environment. Basic outputs such as heat load and temperature profiles are determined. The user can select from a built-in insulation material database or input user defined materials. Existing information has been combined with the new experimental thermal conductivity data produced by the Cryogenics Test Laboratory for cryogenic and vacuum environments, including high vacuum, soft vacuum, and no vacuum. Materials in the design tool include multilayer insulation, aerogel blankets, aerogel bulk-fill, foams, powders, composites, and other insulation system constructions. A comparison of the design tool to a specific composite thermal insulation system is given.

  16. Using Aerogel-Based Insulation Material To Prevent Foam Loss on the Liquid-Hydrogen Intertank

    NASA Technical Reports Server (NTRS)

    2008-01-01

    Uninsulated areas on cryogenic propellant tanks and feedlines cause moisture in the air to condense or ice to form. Flange joints, bracket supports, expansion bellows, and other cavities are uninsulated by design. These areas cannot be sealed because conventional thermal insulation materials would restrict mechanical articulations. Aerogel-based thermal insulation systems are able to seal critical locations such as the liquid-oxygen (LO2) feedline bellows. A new thermal insulation system was also necessary between the intertank wall, flange, and the liquid-hydrogen (LH2) tank dome, where there is a cavity (or crevice) with an exposed 20-K surface. When nitrogen gas is used for purging within the intertank volume, it condenses on this cold surface. Some solid nitrogen may also form on the colder side of the crevice. Voids or discontinuities within the foam can pressurize and cause areas of foam to weaken and break off, reducing thermal efficiency and creating potentially dangerous debris. To prevent this foam loss, we developed a thermal insulation system using bulk-fill aerogel material and demonstrated it with a one-tenth-scale model of the LH2 intertank flange area

  17. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, R.W.; Hrubesh, L.W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner is disclosed. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50--800 kg/m{sup 3} (0.05--0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization. 4 figs.

  18. Compression molding of aerogel microspheres

    DOEpatents

    Pekala, Richard W.; Hrubesh, Lawrence W.

    1998-03-24

    An aerogel composite material produced by compression molding of aerogel microspheres (powders) mixed together with a small percentage of polymer binder to form monolithic shapes in a cost-effective manner. The aerogel composites are formed by mixing aerogel microspheres with a polymer binder, placing the mixture in a mold and heating under pressure, which results in a composite with a density of 50-800 kg/m.sup.3 (0.05-0.80 g/cc). The thermal conductivity of the thus formed aerogel composite is below that of air, but higher than the thermal conductivity of monolithic aerogels. The resulting aerogel composites are attractive for applications such as thermal insulation since fabrication thereof does not require large and expensive processing equipment. In addition to thermal insulation, the aerogel composites may be utilized for filtration, ICF target, double layer capacitors, and capacitive deionization.

  19. System and method for suppressing sublimation using opacified aerogel

    NASA Technical Reports Server (NTRS)

    Sakamoto, Jeff S. (Inventor); Snyder, G. Jeffrey (Inventor); Calliat, Thierry (Inventor); Fleurial, Jean-Pierre (Inventor); Jones, Steven M. (Inventor); Palk, Jong-Ah (Inventor)

    2008-01-01

    The present invention relates to a castable, aerogel-based, ultra-low thermal conductivity opacified insulation to suppress sublimation. More specifically, the present invention relates to an aerogel opacified with various opacifying or reflecting constituents to suppress sublimation and provide thermal insulation in thermoelectric modules. The opacifying constituent can be graded within the aerogel for increased sublimation suppression, and the density of the aerogel can similarly be graded to achieve optimal thermal insulation and sublimation suppression.

  20. Uncooled thin film pyroelectric IR detector with aerogel thermal isolation

    SciTech Connect

    Ruffner, J.A.; Clem, P.G.; Tuttle, B.A.

    1998-01-01

    Uncooled pyroelectric IR imaging systems, such as night vision goggles, offer important strategic advantages in battlefield scenarios and reconnaissance surveys. Until now, the current technology for fabricating these devices has been limited by low throughput and high cost which ultimately limit the availability of these sensor devices. We have developed and fabricated an alternative design for pyroelectric IR imaging sensors that utilizes a multilayered thin film deposition scheme to create a monolithic thin film imaging element on an active silicon substrate for the first time. This approach combines a thin film pyroelectric imaging element with a thermally insulating SiO{sub 2} aerogel thin film to produce a new type of uncooled IR sensor that offers significantly higher thermal, spatial, and temporal resolutions at a substantially lower cost per unit. This report describes the deposition, characterization and optimization of the aerogel thermal isolation layer and an appropriate pyroelectric imaging element. It also describes the overall integration of these components along with the appropriate planarization, etch stop, adhesion, electrode, and blacking agent thin film layers into a monolithic structure. 19 refs., 8 figs., 6 tabs.

  1. Thermal insulation protection means

    NASA Technical Reports Server (NTRS)

    Dotts, R. L.; Smith, J. A.; Strouhal, G. (Inventor)

    1979-01-01

    A system for providing thermal insulation for portions of a spacecraft which do not exceed 900 F during ascent or reentry relative to the earth's atmosphere is described. The thermal insulation is formed of relatively large flexible sheets of needled Nomex felt having a flexible waterproof coating. The thickness of the felt is sized to protect against projected temperatures and is attached to the structure by a resin adhesive. Vent holes in the sheets allow ventilation while maintaining waterproofing. The system is heat treated to provide thermal stability.

  2. Ambient Dried Aerogels

    NASA Technical Reports Server (NTRS)

    Jones, Steven M.; Paik, Jong-Ah

    2013-01-01

    A method has been developed for creating aerogel using normal pressure and ambient temperatures. All spacecraft, satellites, and landers require the use of thermal insulation due to the extreme environments encountered in space and on extraterrestrial bodies. Ambient dried aerogels introduce the possibility of using aerogel as thermal insulation in a wide variety of instances where supercritically dried aerogels cannot be used. More specifically, thermoelectric devices can use ambient dried aerogel, where the advantages are in situ production using the cast-in ability of an aerogel. Previously, aerogels required supercritical conditions (high temperature and high pressure) to be dried. Ambient dried aerogels can be dried at room temperature and pressure. This allows many materials, such as plastics and certain metal alloys that cannot survive supercritical conditions, to be directly immersed in liquid aerogel precursor and then encapsulated in the final, dried aerogel. Additionally, the metalized Mylar films that could not survive the previous methods of making aerogels can survive the ambient drying technique, thus making multilayer insulation (MLI) materials possible. This results in lighter insulation material as well. Because this innovation does not require high-temperature or high-pressure drying, ambient dried aerogels are much less expensive to produce. The equipment needed to conduct supercritical drying costs many tens of thousands of dollars, and has associated running expenses for power, pressurized gasses, and maintenance. The ambient drying process also expands the size of the pieces of aerogel that can be made because a high-temperature, high-pressure system typically has internal dimensions of up to 30 cm in diameter and 60 cm in height. In the case of this innovation, the only limitation on the size of the aerogels produced would be in the ability of the solvent in the wet gel to escape from the gel network.

  3. Thermal insulated glazing unit

    DOEpatents

    Selkowitz, Stephen E.; Arasteh, Dariush K.; Hartmann, John L.

    1991-01-01

    An improved insulated glazing unit is provided which can attain about R5 to about R10 thermal performance at the center of the glass while having dimensions about the same as those of a conventional double glazed insulated glazing unit. An outer glazing and inner glazing are sealed to a spacer to form a gas impermeable space. One or more rigid, non-structural glazings are attached to the inside of the spacer to divide the space between the inner and outer glazings to provide insulating gaps between glazings of from about 0.20 inches to about 0.40 inches. One or more glazing surfaces facing each thermal gap are coated with a low emissivity coating. Finally, the thermal gaps are filled with a low conductance gas such as krypton gas.

  4. Thermal insulated glazing unit

    DOEpatents

    Selkowitz, S.E.; Arasteh, D.K.; Hartmann, J.L.

    1988-04-05

    An improved insulated glazing unit is provided which can attain about R5 to about R10 thermal performance at the center of the glass while having dimensions about the same as those of a conventional double glazed insulated glazing unit. An outer glazing and inner glazing are sealed to a spacer to form a gas impermeable space. One or more rigid, non-structural glazings are attached to the inside of the spacer to divide the space between the inner and outer glazings to provide insulating gaps between glazings of from about 0.20 inches to about 0.40 inches. One or more glazing surfaces facing each thermal gap are coated with a low emissivity coating. Finally, the thermal gaps are filled with a low conductance gas such as krypton gas. 2 figs.

  5. Thermal insulating material

    SciTech Connect

    Billings, P.J.

    1981-12-08

    A thermal insulating material which includes silicone coated perlite providing thermal insulation, powdered perlite to fill in the gaps between the silicone coated perlite particle, and a specially formulated binder for the perlite is disclosed. The binder has a powder portion comprising a mixture of gypsum and cement for strength and a liquid portion comprising polyvinyl acetate, a colloid and water. After these materials are mixed in proper proportions, water is added to provide the fluidity necessary for application, such as by spraying or molding into prefabricated panels.

  6. THERMAL INSULATION SYSTEMS

    NASA Technical Reports Server (NTRS)

    Augustynowicz, Stanislaw D. (Inventor); Fesmire, James E. (Inventor)

    2005-01-01

    Thermal insulation systems and with methods of their production. The thermal insulation systems incorporate at least one reflection layer and at least one spacer layer in an alternating pattern. Each spacer layer includes a fill layer and a carrier layer. The fill layer may be separate from the carrier layer, or it may be a part of the carrier layer, i.e., mechanically injected into the carrier layer or chemically formed in the carrier layer. Fill layers contain a powder having a high surface area and low bulk density. Movement of powder within a fill layer is restricted by electrostatic effects with the reflection layer combined with the presence of a carrier layer, or by containing the powder in the carrier layer. The powder in the spacer layer may be compressed from its bulk density. The thermal insulation systems may further contain an outer casing. Thermal insulation systems may further include strips and seams to form a matrix of sections. Such sections serve to limit loss of powder from a fill layer to a single section and reduce heat losses along the reflection layer.

  7. Technical applications of aerogels

    SciTech Connect

    Hrubesh, L.W.

    1997-08-18

    Aerogel materials posses such a wide variety of exceptional properties that a striking number of applications have developed for them. Many of the commercial applications of aerogels such as catalysts, thermal insulation, windows, and particle detectors are still under development and new application as have been publicized since the ISA4 Conference in 1994: e.g.; supercapacitors, insulation for heat storage in automobiles, electrodes for capacitive deionization, etc. More applications are evolving as the scientific and engineering community becomes familiar with the unusual and exceptional physical properties of aerogels, there are also scientific and technical application, as well. This paper discusses a variety of applications under development at Lawrence Livermore National Laboratory for which several types of aerogels are formed in custom sizes and shapes. Particular discussions will focus on the uses of aerogels for physics experiments which rely on the exceptional, sometimes unique, properties of aerogels.

  8. Thermal insulated building slab

    SciTech Connect

    Hacker, J. H.

    1985-06-25

    A thermally insulated building foundation structure comprising a monolithic poured concrete foundation extending about the perimeter of a building site and having a plurality of elongate straight sides with flat, vertical outside surfaces with lower portions below the surface of the ground and upper portions above the surface of the ground and having flat, horizontal top surfaces, a thermal insulating girdle about the perimeter of the upper portion of the foundation comprised of a plurality of elongate straight horizontal channel sections in end to end relationship and having vertical outside walls defining the outside surface of said upper portion of the foundation, horizontal top walls defining the outer portion of said top surface of the foundation, horizontal bottom walls and upper and lower flanges on inner edges of the top and bottom walls and cores of thermal insulating material filling the channel sections; and a plurality of anchor units spaced about the girdle and having inner deadman portions set in the concrete and outer portions in secure engagement with the flanges of the channel sections.

  9. Peg supported thermal insulation panel

    DOEpatents

    Nowobilski, J.J.; Owens, W.J.

    1985-04-30

    A thermal insulation panel which is lightweight, load bearing, accommodates thermal stress, and has excellent high temperature insulation capability comprises high performance insulation between thin metal walls supported by high density, high strength glass pegs made in compliance with specified conditions of time, temperature and pressure. 2 figs.

  10. Peg supported thermal insulation panel

    DOEpatents

    Nowobilski, Jeffert J.; Owens, William J.

    1985-01-01

    A thermal insulation panel which is lightweight, load bearing, accommodates thermal stress, and has excellent high temperature insulation capability comprising high performance insulation between thin metal walls supported by high density, high strength glass pegs made in compliance with specified conditions of time, temperature and pressure.

  11. Thermal Insulation Test Apparatuses

    NASA Technical Reports Server (NTRS)

    Berman, Brion

    2005-01-01

    The National Aeronautics and Space Administration (NASA) seeks to license its Thermal Insulation Test Apparatuses. Designed by the Cryogenics Test Laboratory at the John F. Kennedy Space Center (KSC) in Florida, these patented technologies (U.S. Patent Numbers: Cryostat 1 - 6,742,926, Cryostat 2 - 6,487,866, and Cryostat 4 - 6,824,306) allow manufacturers to fabricate and test cryogenic insulation at their production and/or laboratory facilities. These new inventions allow for the thermal performance characterization of cylindrical and flat specimens (e.g., bulk-fill, flat-panel, multilayer, or continuously rolled) over the full range of pressures, from high vacuum to no vacuum, and over the full range of temperatures from 77K to 300K. In today's world, efficient, low-maintenance, low-temperature refrigeration is taking a more significant role, from the food industry, transportation, energy, and medical applications to the Space Shuttle. Most countries (including the United States) have laws requiring commercially available insulation materials to be tested and rated by an accepted methodology. The new Cryostat methods go beyond the formal capabilities of the ASTM methods to provide testing for real systems, including full-temperature differences plus full-range vacuum conditions.

  12. Uncooled thin film infrared imaging device with aerogel thermal isolation: Deposition and planarization techniques

    SciTech Connect

    Ruffner, J.A.; Clem, P.G.; Tuttle, B.A.; Brinker, C.J.; Sriram, C.S.; Bullington, J.A.

    1998-04-01

    The authors have successfully integrated a thermally insulating silica aerogel thin film into a new uncooled monolithic thin film infrared (IR) imaging device. Compared to other technologies (bulk ceramic and microbridge), use of an aerogel layer provides superior thermal isolation of the pyroelectric imaging element from the relatively massive heat sinking integrated circuit. This results in significantly higher thermal and temporal resolutions. They have calculated noise equivalent temperature differences of 0.04--0.10 C from a variety of Pb{sub x}Zr{sub y}Ti{sub 1{minus}y}O{sub 3} (PZT) and Pb{sub x}La{sub 1{minus}x}Zr{sub y}Ti{sub 1{minus}y}O{sub 3} (PLZT) pyroelectric imaging elements in monolithic structures. In addition, use of aerogels results in an easier, less expensive fabrication process and a more robust device. Fabrication of these monolithic devices entails sol-gel deposition of the aerogel, sputter deposition of the electrodes, and solution chemistry deposition of the pyroelectric imaging elements. Uniform pyroelectric response is achieved across the device by use of appropriate planarization techniques. These deposition and planarization techniques are described. Characterization of the individual layers and monolithic structure using scanning electron microscopy, atomic force microscopy and Byer-Roundy techniques also is discussed.

  13. Thermal insulation enhancement

    SciTech Connect

    Lambert, G.K.; Misiura, T.D.

    1981-08-25

    A core element, as for example a pipe, tube, hose or the like, has thermal insulation applied thereto in the form of a plurality of layers of tape applied in a continuous process in which conditions are selected to deliberately create wrinkles thereby defining air spaces serving to further reduce the transmission of heat through the composite thermal insulation. The wrinkles may be introduced by wrapping the tape about the pipe at an applied angle greater or smaller than the angle required for a given effective diameter, overlap factor, and width of tape, at the outer surface of the wrap the tape is substantially wrinkle-free and a jacket of polyvinyl chloride or the like is applied thereto. The difference between a theoretical angle of application calculated to produce a wrinkle-free wrap, and an actual angle of application, is progressively lowered in a direction radially outwardly from the tube or other core element, thus causing the wrinkles to become, correspondingly, more and more pronounced in a direction radially inwardly from the jacket. In turn, the air spaces or voids are thereby caused to become progressively enlarged in the radial inward direction, becoming maximized at the surface of the core, that is, at the precise location which has the highest thermal gradient.

  14. Polyolefin-Based Aerogels

    NASA Technical Reports Server (NTRS)

    Lee, Je Kyun; Gould, George

    2012-01-01

    An organic polybutadiene (PB) rubberbased aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection, exhibiting the flexibility, resiliency, toughness, and durability typical of the parent polymer, yet with the low density and superior insulation properties associated with the aerogels. The rubbery behaviors of the PB rubber-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogel insulation materials. Additionally, with higher content of hydrogen in their structure, the PB rubber aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. Since PB rubber aerogels also exhibit good hydrophobicity due to their hydrocarbon molecular structure, they will provide better performance reliability and durability as well as simpler, more economic, and environmentally friendly production over the conventional silica or other inorganic-based aerogels, which require chemical treatment to make them hydrophobic. Inorganic aerogels such as silica aerogels demonstrate many unusual and useful properties. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven one promising approach, providing a conveniently fielded form factor that is relatively robust toward handling in industrial environments compared to silica aerogel monoliths. However, the flexible silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain applications. Although the cross-linked organic aerogels such as resorcinol-formaldehyde (RF), polyisocyanurate, and cellulose aerogels show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient

  15. Material Properties for Fiber-Reinforced Silica Aerogels

    NASA Technical Reports Server (NTRS)

    White, Susan; Rouanet, Stephane; Moses, John; Arnold, James O. (Technical Monitor)

    1994-01-01

    Ceramic fiber-reinforced silica aerogels are novel materials for high performance insulation, including thermal protection materials. Experimental data are presented for the thermal and mechanical properties, showing the trends exhibited over a range of fiber loadings and silica aerogel densities. Test results are compared to that of unreinforced bulk aerogels.

  16. Advanced Aerogel Technology

    NASA Technical Reports Server (NTRS)

    Jones, Steven

    2013-01-01

    The JPL Aerogel Laboratory has made aerogels for NASA flight missions, e.g., Stardust, 2003 Mars Exploration Rovers and the 2011 Mars Science Laboratory, as well as NASA research projects for the past 14 years. During that time it has produced aerogels of a range of shapes, sizes, densities and compositions. Research is ongoing in the development of aerogels for future sample capture and return missions and for thermal insulation for both spacecraft and scientific instruments. For the past several years, the JPL Aerogel Laboratory has been developing, producing and testing a new composite material for use as the high temperature thermal insulation in the Advanced Sterling Radioisotope Generator (ASRG) being developed by Lockheed Martin and NASA. The composite is made up of a glass fiber felt, silica aerogel, Titania powder, and silica powder. The oxide powders are included to reduce irradiative heat transport at elevated temperatures. These materials have thermal conductivity values that are the same as the best commercially produced high temperature insulation materials, and yet are 40% lighter. By greatly reducing the amount of oxide powder in the composite, the density, and therefore for the value of the thermal conductivity, would be reduced. The JPL Aerogel Laboratory has experimented with using glass fiber felt, expanded glass fiber felt and loose fibers to add structural integrity to silica aerogels. However, this work has been directed toward high temperature applications. By conducting a brief investigation of the optimal combination of fiber reinforcement and aerogel density, a durable, extremely efficient thermal insulation material for ambient temperature applications would be produced. If a transparent thermal insulation is desired, then aerogel is an excellent candidate material. At typical ambient temperatures, silica aerogel prevents the transport of heat via convection and conduction due to its highly porous nature. To prevent irradiative thermal

  17. Composite, Cryogenic, Conformal, Common Bulkhead, Aerogel-Insulated Tank (CBAT) Materials and Processing Methodologies

    NASA Technical Reports Server (NTRS)

    Kovach, Michael P.; Roberts, J. Keith; Finckenor, Jeffrey L.; McMahon, William M.; Clinton, R. G., Jr. (Technical Monitor)

    2000-01-01

    A viewgraph presentation outlines the current status and future activities of the composite, cryogenic, conformal, common bulkhead, aerogel-insulated tank (CBAT). Each term (composite, cryogenic, conformal, etc.) is explained. The fabrication method for the CBAT is described, including challenges and their solutions. Near term and long term goals are discussed.

  18. Aerogel/polymer composite materials

    NASA Technical Reports Server (NTRS)

    Williams, Martha K. (Inventor); Smith, Trent M. (Inventor); Fesmire, James E. (Inventor); Roberson, Luke B. (Inventor); Clayton, LaNetra M. (Inventor)

    2010-01-01

    The invention provides new composite materials containing aerogels blended with thermoplastic polymer materials at a weight ratio of aerogel to thermoplastic polymer of less than 20:100. The composite materials have improved thermal insulation ability. The composite materials also have better flexibility and less brittleness at low temperatures than the parent thermoplastic polymer materials.

  19. Thermal Conductivity of Powder Insulations Below 180 K

    NASA Astrophysics Data System (ADS)

    Barrios, M. N.; Choi, Y. S.; Van Sciver, S. W.

    2008-03-01

    We have measured the thermal conductivity of aerogel beads and glass microspheres at average temperatures ranging from 30 K to 180 K. The measuring device consists of two closed, concentric cylinders suspended inside of a vacuum insulated cryostat. The insulation being tested occupies the annular space between the cylinders. A single stage Gifford-McMahon cryocooler, thermally anchored to the outer cylinder, cools the apparatus to a desired temperature range. A heater mounted on the inner cylinder generates uniform heat flux through the insulating material between the two cylinders. During each measurement, a temperature difference of roughly 10 K across the insulation is maintained. Fourier's law of heat conduction is used to relate the temperature difference between the two cylinders and the applied heating power to a bulk effective thermal conductivity of the powder insulation. Data were collected for aerogel beads between 30 K and 80 K and for glass bubbles between 30 K and 180 K. Results are compared to data from the literature.

  20. Mechanically Strong, Polymer Cross-linked Aerogels (X-Aerogels)

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas

    2006-01-01

    Aerogels comprise a class of low-density, high porous solid objects consisting of dimensionally quasi-stable self-supported three-dimensional assemblies of nanoparticles. Aerogels are pursued because of properties above and beyond those of the individual nanoparticles, including low thermal conductivity, low dielectric constant and high acoustic impedance. Possible applications include thermal and vibration insulation, dielectrics for fast electronics, and hosting of functional guests for a wide variety of optical, chemical and electronic applications. Aerogels, however, are extremely fragile materials, hence they have found only limited application in some very specialized environments, for example as Cerenkov radiation detectors in certain types of nuclear reactors, aboard spacecraft as collectors of hypervelocity particles (refer to NASA's Stardust program) and as thermal insulators on planetary vehicles on Mars (refer to Sojourner Rover in 1997 and Spirit and Opportunity in 2004). Along these lines, the X-Aerogel is a new NASA-developed strong lightweight material that has resolved the fragility problem of traditional (native) aerogels. X-Aerogels are made by applying a conformal polymer coating on the surfaces of the skeletal nanoparticles of native aerogels (see Scanning Electron Micrographs). Since the relative amounts of the polymeric crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by the templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by remplated casting of polymer on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralighweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the the thermal conductivity of styrofoam. X-Aerogels

  1. A ceramic composite thermal insulation

    NASA Technical Reports Server (NTRS)

    1967-01-01

    Ceramic composite thermal insulation comprised of alumina-silica fibers, pigmentary potassium titanate, and asbestos fibers, bonded with a colloidal silica sol has improved insulating capabilities to both radiant and convective heat. Gelation of the colloidal silica sol prevents binder migration.

  2. Thermal insulation blanket material

    NASA Technical Reports Server (NTRS)

    Pusch, R. H.

    1982-01-01

    A study was conducted to provide a tailorable advanced blanket insulation based on a woven design having an integrally woven core structure. A highly pure quartz yarn was selected for weaving and the cells formed were filled with a microquartz felt insulation.

  3. Thermal Response Of Composite Insulation

    NASA Technical Reports Server (NTRS)

    Stewart, David A.; Leiser, Daniel B.; Smith, Marnell; Kolodziej, Paul

    1988-01-01

    Engineering model gives useful predictions. Pair of reports presents theoretical and experimental analyses of thermal responses of multiple-component, lightweight, porous, ceramic insulators. Particular materials examined destined for use in Space Shuttle thermal protection system, test methods and heat-transfer theory useful to chemical, metallurgical, and ceramic engineers needing to calculate transient thermal responses of refractory composites.

  4. Composite,Cryogenic, Conformal, Common Bulkhead, Aerogel-Insulated Tank (CBAT)

    NASA Technical Reports Server (NTRS)

    Roberts, J. K.; Kovach, M. P.; McMahon, W. M.; Finckenor, J. L.

    2001-01-01

    The objective of the Composite, Cryogenic, Conformal, Common Bulkhead, Aerogel-insulated Tank (CBAT) Program is to evaluate the potential for using various new technologies in next generation Reusable Launch Vehicles (RLVs) through design, fabrication, and testing of a subscale system. The new technologies include polymer matrix composites (PMCs), conformal propellant storage, common bulkhead packaging, and aerogel insulation. The National Aeronautics and Space Administration (NASA) and Thiokol Propulsion from Cordant Technologies are working together to develop a design and the processing methodologies which will allow integration of these technologies into a single structural component assembly. Such integration will significantly decrease subsystem weight and reduce shape, volume, and placement restrictions, thereby enhancing overall launch system performance. This paper/presentation focuses on the challenges related to materials and processes that were encountered and overcome during this program to date.

  5. Polyurea-Based Aerogel Monoliths and Composites

    NASA Technical Reports Server (NTRS)

    Lee, Je Kyun

    2012-01-01

    aerogel insulation material was developed that will provide superior thermal insulation and inherent radiation protection for government and commercial applications. The rubbery polyureabased aerogel exhibits little dustiness, good flexibility and toughness, and durability typical of the parent polyurea polymer, yet with the low density and superior insulation properties associated with aerogels. The thermal conductivity values of polyurea-based aerogels at lower temperature under vacuum pressures are very low and better than that of silica aerogels. Flexible, rubbery polyurea-based aerogels are able to overcome the weak and brittle nature of conventional inorganic and organic aerogels, including polyisocyanurate aerogels, which are generally prepared with the one similar component to polyurethane rubber aerogels. Additionally, with higher content of hydrogen in their structures, the polyurea rubber-based aerogels will also provide inherently better radiation protection than those of inorganic and carbon aerogels. The aerogel materials also demonstrate good hydrophobicity due to their hydrocarbon molecular structure. There are several strategies to overcoming the drawbacks associated with the weakness and brittleness of silica aerogels. Development of the flexible fiber-reinforced silica aerogel composite blanket has proven to be one promising approach, providing a conveniently fielded form factor that is relatively robust in industrial environments compared to silica aerogel monoliths. However, the flexible, silica aerogel composites still have a brittle, dusty character that may be undesirable, or even intolerable, in certain application environments. Although the cross - linked organic aerogels, such as resorcinol- formaldehyde (RF), polyisocyanurate, and cellulose aerogels, show very high impact strength, they are also very brittle with little elongation (i.e., less rubbery). Also, silica and carbon aerogels are less efficient radiation shielding materials due

  6. Insulation products promote thermal efficiency

    SciTech Connect

    Chalmers, R.

    1985-04-01

    The judicious use of thermal insulation products in non-residential buildings can provide a number of advantages including increased energy efficiency, lower first costs (by avoiding overside HVAC systems), improved fire safety and better acoustics. Thermal insulation products are those products which retard the flow of heat energy. Materials include glass, plastics, and organic materials such as wood fibers, vermiculite and perlite. Forms range from the familiar batts and blankets of glass fibers to foamed plastic, rigid boards, losse fill and systems combining two or more products, such as polystyrene boards covered with insulating plaster. The R values of selected insulation materials with a cost/sq. ft. of each material at R 10 are given. Costs cover both the material and installation and may vary depending on local conditions.

  7. Aerogel: Tile Composites Toughen a Brittle Superinsulation

    NASA Technical Reports Server (NTRS)

    White, Susan; Rasky, Daniel; Arnold, James O. (Technical Monitor)

    1998-01-01

    Pure aerogels, though familiar in the laboratory for decades as exotic lightweight insulators with unusual physical properties, have had limited industrial applications due to their low strength and high brittleness. Composites formed of aerogels and the ceramic fiber matrices like those used as space shuttle tiles bypass the fragility of pure aerogels and can enhance the performance of space shuttle tiles in their harsh operating environment. Using a layer of aerogel embedded in a tile may open up a wide range of applications where thermal insulation, gas convection control and mechanical strength matter.

  8. The efficiency of night insulation using aerogel-filled polycarbonate panels during the heating season

    NASA Astrophysics Data System (ADS)

    Adelsberger, Kathleen

    Energy is the basis for modern life. All modern technology from a simple coffee maker to massive industrial facilities is powered by energy. While the demand for energy is increasing, our planet is suffering from the consequences of using fossil fuels to generate electricity. Therefore, the world is looking at clean energy and solar power to minimize this effect on our environment. However, saving energy is extremely important even for clean energy. The more we save the less we have to generate. Heat retention in buildings is one step towards achieving passive heating. Therefore, efforts are made to prevent heat from escaping buildings through the glass during cold nights. Movable insulation is a way to increase the insulation value of the glass to reduce heat loss towards the outdoor. This thesis examines the performance of the aerogel-filled polycarbonate movable panels in the Ecohawks building, a building located on the west campus of The University of Kansas. Onsite tests were performed using air and surface temperature sensors to determine the effectiveness of the system. Computer simulations were run by Therm 7.2 simulation software to explore alternative design options. A cost analysis was also performed to evaluate the feasibility of utilizing movable insulation to reduce the heating bills during winter. Results showed that sealed movable insulation reduces heat loss through the glazing by 67.5%. Replacing aerogel with XPS panels reduces this percentage to 64.3%. However, it reduces the cost of the insulation material by 98%.

  9. Sorption Properties of Aerogel in Liquid Nitrogen

    NASA Technical Reports Server (NTRS)

    Johnson, Wesley L.

    2006-01-01

    Aerogel products are now available as insulation materials of the future. The Cryogenics Test Laboratory at the NASA Kennedy Space Center is developing aerogel-based thermal insulation systems for space launch applications. Aerogel beads (Cabot Nanogel ) and aerogel blankets (Aspen Aerogels Spaceloft ) have outstanding ambient pressure thermal performance that makes them useful for applications where sealing is not possible. Aerogel beads are open-celled silicone dioxide and have tiny pores that run throughout the body of the bead. It has also recently been discovered that aerogel beads can be used as a filtering device for aqueous compounds at room temperature. With their hydrophobic covering, the beads absorb any non-polar substance and they can be chemically altered to absorb hot gases. The combination of the absorption and cryogenic insulating properties of aerogel beads have never been studied together. For future cryogenic insulation applications, it is crucial to know how the beads react while immersed in cryogenic liquids, most notably liquid nitrogen. Aerogel beads in loose-fill situation and aerogel blankets with composite fiber structure have been tested for absorption properties. Depending on the type of aerogel used and the preparation, preliminary results show the material can absorb up to seven times its own weight of liquid nitrogen, corresponding to a volumetric ratio of 0.70 (unit volume nitrogen per unit volume aerogel). These tests allow for an estimate on how much insulation is needed in certain situations. The theory behind the different processes of sorption is necessary for a better understanding of the preparation of the beads before they are used in an insulation system.

  10. Composite Aerogel Multifoil Protective Shielding

    NASA Technical Reports Server (NTRS)

    Jones, Steven M.

    2013-01-01

    New technologies are needed to survive the temperatures, radiation, and hypervelocity particles that exploration spacecraft encounter. Multilayer insulations (MLIs) have been used on many spacecraft as thermal insulation. Other materials and composites have been used as micrometeorite shielding or radiation shielding. However, no material composite has been developed and employed as a combined thermal insulation, micrometeorite, and radiation shielding. By replacing the scrims that have been used to separate the foil layers in MLIs with various aerogels, and by using a variety of different metal foils, the overall protective performance of MLIs can be greatly expanded to act as thermal insulation, radiation shielding, and hypervelocity particle shielding. Aerogels are highly porous, low-density solids that are produced by the gelation of metal alkoxides and supercritical drying. Aerogels have been flown in NASA missions as a hypervelocity particle capture medium (Stardust) and as thermal insulation (2003 MER). Composite aerogel multifoil protective shielding would be used to provide thermal insulation, while also shielding spacecraft or components from radiation and hypervelocity particle impacts. Multiple layers of foil separated by aerogel would act as a thermal barrier by preventing the transport of heat energy through the composite. The silica aerogel would act as a convective and conductive thermal barrier, while the titania powder and metal foils would absorb and reflect the radiative heat. It would also capture small hypervelocity particles, such as micrometeorites, since it would be a stuffed, multi-shock Whipple shield. The metal foil layers would slow and break up the impacting particles, while the aerogel layers would convert the kinetic energy of the particles to thermal and mechanical energy and stop the particles.

  11. Thermal Insulation from Hardwood Residues

    NASA Astrophysics Data System (ADS)

    Sable, I.; Grinfelds, U.; Vikele, L.; Rozenberga, L.; Zeps, M.; Luguza, S.

    2015-11-01

    Adequate heat is one of the prerequisites for human wellbeing; therefore, building insulation is required in places where the outside temperature is not suitable for living. The climate change, with its rising temperatures and longer dry periods, promotes enlargement of the regions with conditions more convenient for hardwood species than for softwood species. Birch (Betula pendula) is the most common hardwood species in Latvia. The aim of this work was to obtain birch fibres from wood residues of plywood production and to form low-density thermal insulation boards. Board formation and production was done in the presence of water; natural binder, fire retardant and fungicide were added in different concentrations. Board properties such as density, transportability or resistance to particulate loss, thermal conductivity and reaction to fire were investigated. This study included thermal insulation boards with the density of 102-120 kg/m3; a strong correlation between density and the binder amount was found. Transportability also improved with the addition of a binder, and 0.1-0.5% of the binder was the most appropriate amount for this purpose. The measured thermal conductivity was in the range of 0.040-0.043 W/(m·K). Fire resistance increased with adding the fire retardant. We concluded that birch fibres are applicable for thermal insulation board production, and it is possible to diversify board properties, changing the amount of different additives.

  12. Loose-fill, thermal insulation

    SciTech Connect

    Nath, N.; Ruff, D.L.

    1981-11-24

    Fire resistant, loose-fill, thermal insulation made of a mixture of particulate expanded perlite and cellulose fiber is described. The mixture is rendered non-settling and resistant to separation by applying a permanently tacky material to the particulate expanded perlite.

  13. Epoxy Crosslinked Silica Aerogels (X-Aerogels)

    NASA Technical Reports Server (NTRS)

    fabrizio, Eve; Ilhan, Faysal; Meador, Mary Ann; Johnston, Chris; Leventis, Nicholas

    2004-01-01

    NASA is interested in the development of strong lightweight materials for the dual role of thermal insulator and structural component for space vehicles; freeing more weight for useful payloads. Aerogels are very-low density materials (0.010 to 0.5 g/cc) that, due to high porosity (meso- and microporosity), can be, depending on the chemical nature of the network, ideal thermal insulators (thermal conductivity approx. 15 mW/mK). However, aerogels are extremely fragile. For practical application of aerogels, one must increase strength without compromising the physical properties attributed to low density. This has been achieved by templated growth of an epoxy polymer layer that crosslinks the "pearl necklace" network of nanoparticles: the framework of a typical silica aerogel. The requirement for conformal accumulation of the epoxy crosslinker is reaction both with the surface of silica and with itself. After cross-linking, the strength of a typical aerogel monolith increases by a factor of 200, in the expense of only a 2-fold increase in density. Strength is increased further by coupling residual unreacted epoxides with diamine.

  14. Thermal shock resistance ceramic insulator

    DOEpatents

    Morgan, Chester S.; Johnson, William R.

    1980-01-01

    Thermal shock resistant cermet insulators containing 0.1-20 volume % metal present as a dispersed phase. The insulators are prepared by a process comprising the steps of (a) providing a first solid phase mixture of a ceramic powder and a metal precursor; (b) heating the first solid phase mixture above the minimum decomposition temperature of the metal precursor for no longer than 30 minutes and to a temperature sufficiently above the decomposition temperature to cause the selective decomposition of the metal precursor to the metal to provide a second solid phase mixture comprising particles of ceramic having discrete metal particles adhering to their surfaces, said metal particles having a mean diameter no more than 1/2 the mean diameter of the ceramic particles, and (c) densifying the second solid phase mixture to provide a cermet insulator having 0.1-20 volume % metal present as a dispersed phase.

  15. Competition between thermal fluctuations and disorder in the crystallization of 4He in aerogel.

    PubMed

    Nomura, Ryuji; Osawa, Aiko; Mimori, Tomohiro; Ueno, Ken-ichi; Kato, Haruko; Okuda, Yuichi

    2008-10-24

    The dynamical transition in the crystallization of 4He in aerogel has been investigated by direct visualization and dynamical phase diagrams have been determined. The crystal-superfluid interface in aerogel advances via creep at high temperatures and avalanches at low temperatures. The transition temperature is higher at a higher interface velocity and lower in higher porosity aerogels. The transition is due to competition between thermal fluctuations and disorder for the crystallization process. PMID:18999765

  16. Synthesis, Processing, and Characterization of Inorganic-Organic Hybrid Cross-Linked Silica, Organic Polyimide, and Inorganic Aluminosilicate Aerogels

    NASA Technical Reports Server (NTRS)

    Nguyen, Baochau N.; Guo, Haiquan N.; McCorkle, Linda S.

    2014-01-01

    As aerospace applications become ever more demanding, novel insulation materials with lower thermal conductivity, lighter weight and higher use temperature are required to fit the aerospace application needs. Having nanopores and high porosity, aerogels are superior thermal insulators, among other things. The use of silica aerogels in general is quite restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extereme aerospace environments. Our research goal is to develop aerogels with better mechanical and environmental stability for a variety of aeronautic and space applications including space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Different type of aerogels including organic-inorganic polymer reinforced (hybrid) silica-based aerogels, polyimide aerogels and inorganic aluminosilicate aerogels have been developed and examined.

  17. Incorporation of graphene nanosheets into cellulose aerogels: enhanced mechanical, thermal, and oil adsorption properties

    NASA Astrophysics Data System (ADS)

    Wan, Caichao; Li, Jian

    2016-02-01

    In this paper, novel graphene/cellulose (GC) aerogels were prepared based on a green NaOH/PEG solution. Scanning electron microscope observation indicates that the three-dimensional network skeleton structure of cellulose aerogels is tightly covered by the compact sheet structure. X-ray diffraction and Raman spectroscopy analyses demonstrate that the graphene nanosheets have been successfully synthesized and embedded in the cellulose aerogels. The incorporation of graphene nanosheets gives rise to the significant improvement in the specific surface area and pore volume, thermal stability, mechanical strength, and oil adsorption efficiency of GC aerogels. Therefore, the green hybrid GC aerogels have more advantages over the pure cellulose aerogels in treating oil-containing wastewater or oil spills under the harsh environment.

  18. Aerogel Composites: Strong and Waterproof

    NASA Technical Reports Server (NTRS)

    White, Susan; Hsu, Ming-ta; Arnold, James O. (Technical Monitor)

    1999-01-01

    Aerogels are exotic materials having superior thermal and physical properties with great potential for both space and industrial uses. Although aerogels are excellent low-density insulators with unique acoustic and optical properties, their commercialization potential is currently limited by moisture absorption, fragility, and cost. This paper describes useful, easily scaled-up solutions to the first two of these three problems. The waterproofing and water-repellent method described here is a cheaper and simpler improvement over previous permanent methods.

  19. Thermally Insulated Glove With Good Tactility

    NASA Technical Reports Server (NTRS)

    Balinskas, R.

    1982-01-01

    Thermally insulated glove contains short, closely-spaced elastomeric pins that insulate without impairing flexibility. By confining pins to the inter-joint areas of palm, fingers and back of the hand, joint mobility is retained. Glove thermal-insulation requirements dictate the relationships among pin length, pin diameter, and number of pins per unit surface length.

  20. Layered composite thermal insulation system for nonvacuum cryogenic applications

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.

    2016-03-01

    A problem common to both space launch applications and cryogenic propulsion test facilities is providing suitable thermal insulation for complex cryogenic piping, tanks, and components that cannot be vacuum-jacketed or otherwise be broad-area-covered. To meet such requirements and provide a practical solution to the problem, a layered composite insulation system has been developed for nonvacuum applications and extreme environmental exposure conditions. Layered composite insulation system for extreme conditions (or LCX) is particularly suited for complex piping or tank systems that are difficult or practically impossible to insulate by conventional means. Consisting of several functional layers, the aerogel blanket-based system can be tailored to specific thermal and mechanical performance requirements. The operational principle of the system is layer-pairs working in combination. Each layer pair is comprised of a primary insulation layer and a compressible radiant barrier layer. Vacuum-jacketed piping systems, whether part of the ground equipment or the flight vehicle, typically include numerous terminations, disconnects, umbilical connections, or branches that must be insulated by nonvacuum means. Broad-area insulation systems, such as spray foam or rigid foam panels, are often the lightweight materials of choice for vehicle tanks, but the plumbing elements, feedthroughs, appurtenances, and structural supports all create "hot spot" areas that are not readily insulated by similar means. Finally, the design layouts of valve control skids used for launch pads and test stands can be nearly impossible to insulate because of their complexity and high density of components and instrumentation. Primary requirements for such nonvacuum thermal insulation systems include the combination of harsh conditions, including full weather exposure, vibration, and structural loads. Further requirements include reliability and the right level of system breathability for thermal

  1. Protective Skins for Aerogel Monoliths

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas; Johnston, James C.; Kuczmarski, Maria A.; Meador, Ann B.

    2007-01-01

    A method of imparting relatively hard protective outer skins to aerogel monoliths has been developed. Even more than aerogel beads, aerogel monoliths are attractive as thermal-insulation materials, but the commercial utilization of aerogel monoliths in thermal-insulation panels has been inhibited by their fragility and the consequent difficulty of handling them. Therefore, there is a need to afford sufficient protection to aerogel monoliths to facilitate handling, without compromising the attractive bulk properties (low density, high porosity, low thermal conductivity, high surface area, and low permittivity) of aerogel materials. The present method was devised to satisfy this need. The essence of the present method is to coat an aerogel monolith with an outer polymeric skin, by painting or spraying. Apparently, the reason spraying and painting were not attempted until now is that it is well known in the aerogel industry that aerogels collapse in contact with liquids. In the present method, one prevents such collapse through the proper choice of coating liquid and process conditions: In particular, one uses a viscous polymer precursor liquid and (a) carefully controls the amount of liquid applied and/or (b) causes the liquid to become cured to the desired hard polymeric layer rapidly enough that there is not sufficient time for the liquid to percolate into the aerogel bulk. The method has been demonstrated by use of isocyanates, which, upon exposure to atmospheric moisture, become cured to polyurethane/polyurea-type coats. The method has also been demonstrated by use of commercial epoxy resins. The method could also be implemented by use of a variety of other resins, including polyimide precursors (for forming high-temperature-resistant protective skins) or perfluorinated monomers (for forming coats that impart hydrophobicity and some increase in strength).

  2. Refractory thermal insulation for smooth metal surfaces

    NASA Technical Reports Server (NTRS)

    1964-01-01

    To protect rocket metal surfaces from engine exhaust heat, a refractory thermal insulation mixture, which adheres to smooth metals, has been developed. Insulation protection over a wide temperature range can be controlled by thickness of the applied mixture.

  3. Influence of Boehmite Precursor on Aluminosilicate Aerogel Pore Structure, Phase Stability and Resistance to Densification at High Temperatures

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Guo, Haiquan; Newlin, Katy N.

    2011-01-01

    Aluminosilicate aerogels are of interest as constituents of thermal insulation systems for use at temperatures higher than those attainable with silica aerogels. It is anticipated that their effectiveness as thermal insulators will be influenced by their morphology, pore size distribution, physical and skeletal densities. The present study focuses on the synthesis of aluminosilicate aerogel from a variety of Boehmite (precursors as the Al source, and tetraethylorthosilicate (TEOS) as the Si source, and the influence of starting powder on pore structure and thermal stability.

  4. Method of thermally insulating a wellbore

    SciTech Connect

    Mckinzie, H.L.

    1981-07-07

    A method is claimed for thermally insulating the borehole of a well in a thermal process for oil recovery by providing in the annular space between the casing and the well tubing a flowable, solid material having thermal insulating properties, such as vermiculite or perlite. Removal of the material is by fluidization thereof.

  5. Mesoporous polyurethane aerogels for thermal superinsulation: Textural properties and thermal conductivity

    NASA Astrophysics Data System (ADS)

    Diascorn, N.; Sallee, H.; Calas, S.; Rigacci, A.; Achard, P.

    2015-07-01

    Organic aerogels based on polyurethane were elaborated via sol-gel synthesis and dried with supercritical carbon dioxide (CO2). The influence of the catalyst concentration was investigated, first in order to decrease the reaction kinetics, then to study its impact on the obtained materials properties. It was shown that this parameter also influences the global shrinkage and the bulk density of the resulting materials. Its effect on the dry materials was studied in terms of morphological, textural and thermal properties in order to determine the main correlations thanks to scanning electron microscopy (SEM), nitrogen adsorption, non-intrusive mercury porosimetry and thermal conductivity measurements. Results allowed us to demonstrate a correlation between the bulk density, the texture and the thermal conductivity of this family of polyurethane aerogels and to determine an optimal density range for thermal performance associated with a fine internal mesoporous texture.

  6. Mechanical Properties of Aerogels

    NASA Technical Reports Server (NTRS)

    Parmenter, Kelly E.; Milstein, Frederick

    1995-01-01

    Aerogels are extremely low density solids that are characterized by a high porosity and pore sizes on the order of nanometers. Their low thermal conductivity and sometimes transparent appearance make them desirable for applications such as insulation in cryogenic vessels and between double paned glass in solar architecture. An understanding of the mechanical properties of aerogels is necessary before aerogels can be used in load bearing applications. In the present study, the mechanical behavior of various types of fiber-reinforced silica aerogels was investigated with hardness, compression, tension and shear tests. Particular attention was paid to the effects of processing parameters, testing conditions, storage environment, and age on the aerogels' mechanical response. The results indicate that the addition of fibers to the aerogel matrix generally resulted in softer, weaker materials with smaller elastic moduli. Furthermore, the testing environment significantly affected compression results. Tests in ethanol show an appreciable amount of scatter, and are not consistent with results for tests in air. In fact, the compression specimens appeared to crack and begin to dissolve upon exposure to the ethanol solution. This is consistent with the inherent hydrophobic nature of these aerogels. In addition, the aging process affected the aerogels' mechanical behavior by increasing their compressive strength and elastic moduli while decreasing their strain at fracture. However, desiccation of the specimens did not appreciably affect the mechanical properties, even though it reduced the aerogel density by removing trapped moisture. Finally, tension and shear test results indicate that the shear strength of the aerogels exceeds the tensile strength. This is consistent with the response of brittle materials. Future work should concentrate on mechanical testing at cryogenic temperatures, and should involve more extensive tensile tests. Moreover, before the mechanical response

  7. Hybrid aerogel rigid ceramic fiber insulation and method of producing same

    NASA Technical Reports Server (NTRS)

    Barney, Andrea O. (Inventor); Heng, Vann (Inventor); Oka, Kris Shigeko (Inventor); Santos, Maryann (Inventor); Zinn, Alfred A. (Inventor); Droege, Michael (Inventor)

    2004-01-01

    A hybrid insulation material comprises of porous ceramic substrate material impregnated with nanoporous material and method of making the same is the topic of this invention. The porous substrate material has bulk density ranging from 6 to 20 lb/ft.sup.3 and is composed of about 60 to 80 wt % silica (SiO.sub.2) 20 to 40 wt % alumina (Al.sub.2 O.sub.3) fibers, and with about 0.1 to 1.0 wt % boron-containing constituent as the sintering agent. The nanoporous material has density ranging from 1.0 to 10 lb/ft.sup.3 and is either fully or partially impregnated into the substrate to block the pores, resulting in substantial reduction in conduction via radiation and convention. The nanoporous material used to impregnate the fiber substrate is preferably formed from a precursor of alkoxysilane, alcohol, water, and an acid or base catalyst for silica aerogels, and from a precursor of aluminum alkoxide, alcohol, water, and an acid or base catalyst for alumina aerogels.

  8. Composite Silica Aerogels Opacified with Titania

    NASA Technical Reports Server (NTRS)

    Paik, Jon-Ah; Sakamoto, Jeffrey; Jones, Steven; Fleurial, Jean-Pierre; DiStefano, Salvador; Nesmith, Bill

    2009-01-01

    A further improvement has been made to reduce the high-temperature thermal conductivities of the aerogel-matrix composite materials described in Improved Silica Aerogel Composite Materials (NPO-44287), NASA Tech Briefs, Vol. 32, No. 9 (September 2008), page 50. Because the contribution of infrared radiation to heat transfer increases sharply with temperature, the effective high-temperature thermal conductivity of a thermal-insulation material can be reduced by opacifying the material to reduce the radiative contribution. Therefore, the essence of the present improvement is to add an opacifying constituent material (specifically, TiO2 powder) to the aerogel-matrix composites.

  9. Method for producing metal oxide aerogels

    DOEpatents

    Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

    1995-04-25

    A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm{sup 3} and greater than 0.27g/cm{sup 3}. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods. 8 figs.

  10. Method for producing metal oxide aerogels

    DOEpatents

    Tillotson, Thomas M.; Poco, John F.; Hrubesh, Lawrence W.; Thomas, Ian M.

    1995-01-01

    A two-step hydrolysis-condensation method was developed to form metal oxide aerogels of any density, including densities of less than 0.003g/cm.sup.3 and greater than 0.27g/cm.sup.3. High purity metal alkoxide is reacted with water, alcohol solvent, and an additive to form a partially condensed metal intermediate. All solvent and reaction-generated alcohol is removed, and the intermediate is diluted with a nonalcoholic solvent. The intermediate can be stored for future use to make aerogels of any density. The aerogels are formed by reacting the intermediate with water, nonalcoholic solvent, and a catalyst, and extracting the nonalcoholic solvent directly. The resulting monolithic aerogels are hydrophobic and stable under atmospheric conditions, and exhibit good optical transparency, high clarity, and homogeneity. The aerogels have high thermal insulation capacity, high porosity, mechanical strength and stability, and require shorter gelation times than aerogels formed by conventional methods.

  11. Improved Silica Aerogel Composite Materials

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

    2008-01-01

    A family of aerogel-matrix composite materials having thermal-stability and mechanical- integrity properties better than those of neat aerogels has been developed. Aerogels are known to be excellent thermal- and acoustic-insulation materials because of their molecular-scale porosity, but heretofore, the use of aerogels has been inhibited by two factors: (1) Their brittleness makes processing and handling difficult. (2) They shrink during production and shrink more when heated to high temperatures during use. The shrinkage and the consequent cracking make it difficult to use them to encapsulate objects in thermal-insulation materials. The underlying concept of aerogel-matrix composites is not new; the novelty of the present family of materials lies in formulations and processes that result in superior properties, which include (1) much less shrinkage during a supercritical-drying process employed in producing a typical aerogel, (2) much less shrinkage during exposure to high temperatures, and (3) as a result of the reduction in shrinkage, much less or even no cracking.

  12. Study on Unit Cell Models and the Effective Thermal Conductivities of Silica Aerogel.

    PubMed

    Liu, He; Li, Zeng-Yao; Zhao, Xin-Peng; Tao, Wen-Quan

    2015-04-01

    In this paper, two modified unit cell models, truncated octahedron and cubic array of intersecting square rods with 45-degree rotation, are developed in consideration of the tortuous path of heat conduction in solid skeleton of silica aerogel. The heat conduction is analyzed for each model and the expressions of effective thermal conductivity of the modified unit cell models are derived. Considering the random microstructure of silica aerogel, the probability model is presented. We also discuss the effect of the thermal conductivity of aerogel backbone. The effective thermal conductivities calculated by the proposed probability model are in good agreement with available experimental data when the density of the aerogel is 110 kg/m3. PMID:26353566

  13. Flexible aerogel composite for mechanical stability and process of fabrication

    SciTech Connect

    Coronado, P.R.; Poco, J.F.

    1999-10-26

    A flexible aerogel and process of fabrication are disclosed. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4--5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

  14. Flexible aerogel composite for mechanical stability and process of fabrication

    DOEpatents

    Coronado, Paul R.; Poco, John F.

    2000-01-01

    A flexible aerogel and process of fabrication. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4-5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

  15. Flexible aerogel composite for mechanical stability and process of fabrication

    DOEpatents

    Coronado, Paul R.; Poco, John F.

    1999-01-01

    A flexible aerogel and process of fabrication. An aerogel solution is mixed with fibers in a mold and allowed to gel. The gel is then processed by supercritical extraction, or by air drying, to produce a flexible aerogel formed to the shape of the mold. The flexible aerogel has excellent thermal and acoustic properties, and can be utilized in numerous applications, such as for energy absorption, insulation (temperature and acoustic), to meet the contours of aircraft shapes, and where space is limited since an inch of aerogel is a 4-5 times better insulator than an inch of fiberglass. The flexible aerogel may be of an inorganic (silica) type or an organic (carbon) type, but containing fibers, such as glass or carbon fibers.

  16. Thermal conductivity studies of a polyurea cross-linked silica aerogel-RTV 655 compound for cryogenic propellant tank applications in space

    NASA Astrophysics Data System (ADS)

    Sabri, F.; Marchetta, J.; Smith, K. M.

    2013-10-01

    Silica-based aerogel is an ideal thermal insulator with a makeup of up to 99% air associated with the highly porous nature of this material. Polyurea cross-linked silica aerogel (PCSA) has superior mechanical properties compared to the native aerogels yet retains the highly porous open pore network and functions as an ideal thermal insulator with added load-bearing capability necessary for some applications. Room temperature vulcanizing rubber-RTV 655—is a space qualified elastomeric thermal insulator and encapsulant with high radiation and temperature tolerance as well as chemical resistance. Storage and transport of cryogenic propellant liquids is an integral part of the success of future space exploratory missions and is an area under constant development. Limitations and shortcomings of current cryogenic tank materials and insulation techniques such as non-uniform insulation layers, self-pressurization, weight and durability issues of the materials used, has motivated the quest for alternative materials. Both RTV 655 and PCSA are promising space qualified materials with unique and tunable microscopic and macroscopic properties making them attractive candidates for this study. In this work, the effect of PCSA geometry and volume concentration on the thermal behavior of RTV 655—PCSA compound material has been investigated at room temperature and at a cryogenic temperature. Macroscopic and microscopic PCSA material was encapsulated at increasing concentrations in an RTV 655 elastomeric matrix. The effect of pulverization on the nanopores of PCSA as a method for creating large quantities of homogeneous PCSA microparticles has also been investigated and is reported. The PCSA volume concentrations ranged between 22% and 75% for both geometries. Thermal conductivity measurements were performed based on the steady state transient plane source method.

  17. Thermal conductance of space suit insulations, thermal micrometeroid garments, and other insulations

    NASA Technical Reports Server (NTRS)

    Richardson, D. L.; Stevens, J. M.

    1976-01-01

    The thermal protection capabilities of development and operational thermal micrometeroid garments and other insulations were evaluated. The relationship among sample thermal conductance, surface temperature, and compressive loads was empirically defined.

  18. Thermal conductivity measurements of aerogel-impregnated shuttle tile at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Helvensteijn, B. P. M.; Maddocks, J. R.; Salerno, L. J.; Roach, P. R.; Kittel, P.; White, S. M.

    2002-05-01

    New materials are being designed to allow the implementation of innovative concepts in future space transportation vehicles. In present day spacecraft, launch vehicles consist of an overall structure in which the cryogenic propellant tanks are mounted in a framework covered by an aeroshell. In NASA s next generation space transportation vehicles the innovative concept of conformal propellant tanks will be utilized. In addition to containing the propellants the cryogen tanks will serve as part of the main vehicle structure. This concept enables significant reduction in launch mass. Crucial to this approach will be the development of a material that will serve not only as cryogenic insulation on the launchpad and early in flight, but also as a thermal protection system (TPS), protecting the vehicle on re-entry. Prior to selection for this challenging application various material properties are to be assessed. The present paper discusses experimental results on the thermal conductivity of a preliminary candidate material (an aerogel-impregnated shuttle tile) in the presence of helium gas. Data have been taken at room temperature and near 80 K at pressures ranging from 1 atm down to 20 m Torr. The capability to extend the tests down to lower temperatures (4 K) was not utilized considering the noted adsorptive qualities of the open cell structure of the tile.

  19. Vibration and Thermal Cycling Effects on Bulk-fill Insulation Materials for Cryogenic Tanks

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Augustynowicz, S. D.; Nagy, Z. F.; Sojourner, S. J.; Morris, D. L.

    2006-04-01

    Large-scale (1,000,000 liters or more) cryogenic storage tanks are typically perlite-insulated double-walled vessels. Associated problems with perlite, such as mechanical compaction and settling, could be greatly reduced by using newer bulk-fill materials such as glass bubbles or aerogel beads. Using the newer materials should translate to lower life cycle costs and improved system reliability. NASA Kennedy Space Center is leveraging its experience in the areas of materials development, insulation testing, and cryogenic systems design to develop an insulation retrofit option that will meet both industry and NASA requirements. A custom 10-liter dewar test apparatus, developed by the KSC Cryogenics Test Laboratory, was used to determine the vibration and thermal cycling effects on different bulk-fill insulation materials for cryogenic tanks. The testing included liquid-nitrogen boiloff testing and thermal cycling (with vibration) of a number of test dewars. Test results show that glass bubbles have better thermal performance and less mechanical compaction compared to perlite powder. The higher cost of the bulk material should be offset by reduced commodity loss from boiloff and improvements in material handling, evacuation, and vacuum retention. The long-term problem with settling and compaction of perlite should also be eliminated. Aerogel beads are superior for the no-vacuum condition and can now be considered in some applications. Further studies on large-scale systems are presently being pursued.

  20. Tailoring mechanical properties of aerogels for aerospace applications.

    PubMed

    Randall, Jason P; Meador, Mary Ann B; Jana, Sadhan C

    2011-03-01

    Silica aerogels are highly porous solid materials consisting of three-dimensional networks of silica particles and are typically obtained by removing the liquid in silica gels under supercritical conditions. Several unique attributes such as extremely low thermal conductivity and low density make silica aerogels excellent candidates in the quest for thermal insulation materials used in space missions. However, native silica aerogels are fragile at relatively low stresses. More durable aerogels with higher strength and stiffness are obtained by proper selection of silane precursors and by reinforcement with polymers. This paper first presents a brief review of the literature on methods of silica aerogel reinforcement and then discusses our recent activities in improving not only the strength but also the elastic response of polymer-reinforced silica aerogels. Several alkyl-linked bis-silanes were used in promoting flexibility of the silica networks in conjunction with polymer reinforcement by epoxy. PMID:21361281

  1. Mechanically stable thermally crosslinked poly(acrylic acid)/reduced graphene oxide aerogels.

    PubMed

    Ha, Heonjoo; Shanmuganathan, Kadhiravan; Ellison, Christopher J

    2015-03-25

    Graphene oxide (GO) aerogels, high porosity (>99%) low density (∼3-10 mg cm(-3)) porous materials with GO pore walls, are particularly attractive due to their lightweight, high surface area, and potential use in environmental remediation, superhydrophobic and superoleophilic materials, energy storage, etc. However, pure GO aerogels are generally weak and delicate which complicates their handling and potentially limits their commercial implementation. The focus of this work was to synthesize highly elastic, mechanically stable aerogels that are robust and easy to handle without substantially sacrificing their high porosity or low density. To overcome this challenge, a small amount of readily available and thermally cross-linkable poly(acrylic acid) (PAA) was intermixed with GO to enhance the mechanical integrity of the aerogel without disrupting other desirable characteristic properties. This method is a simple straightforward procedure that does not include multistep or complicated chemical reactions, and it produces aerogels with mass densities of about 4-6 mg cm(-3) and >99.6% porosity that can reversibly support up to 10,000 times their weight with full recovery of their original volume. Finally, pressure sensing capabilities were demonstrated and their oil absorption capacities were measured to be around 120 g oil per g aerogel(-1) which highlights their potential use in practical applications. PMID:25714662

  2. Thermal Performance Testing of Cryogenic Insulation Systems

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, Stan D.; Scholtens, Brekke E.

    2007-01-01

    Efficient methods for characterizing thermal performance of materials under cryogenic and vacuum conditions have been developed. These methods provide thermal conductivity data on materials under actual-use conditions and are complementary to established methods. The actual-use environment of full temperature difference in combination with vacuum-pressure is essential for understanding insulation system performance. Test articles include solids, foams, powders, layered blankets, composite panels, and other materials. Test methodology and apparatus design for several insulation test cryostats are discussed. The measurement principle is liquid nitrogen boil-off calorimetry. Heat flux capability ranges from approximately 0.5 to 500 watts per square meter; corresponding apparent thermal conductivity values range from below 0.01 up to about 60 mW/m- K. Example data for different insulation materials are also presented. Upon further standardization work, these patented insulation test cryostats can be available to industry for a wide range of practical applications.

  3. Self-assembled and pyrolyzed carbon aerogels: an overview of their preparation mechanisms, properties and applications

    NASA Astrophysics Data System (ADS)

    Allahbakhsh, Ahmad; Bahramian, Ahmad Reza

    2015-08-01

    An overview of the synthesis conditions and mechanisms for the fabrication of different types of carbon aerogels, as well as the structural and functional properties of these materials, is presented here. In this overview, carbon aerogels are classified into three major categories: (i) conventional pyrolyzed organic-based carbon aerogels, which are products of the pyrolysis process of organic aerogels; (ii) self-assembled carbon aerogels, which are products of a reduction process; and (iii) nanocomposite carbon aerogels. Synthesis mechanisms for the sol-gel process of organic aerogels are reviewed using different mechanisms suggested in the literature. Moreover, the overall fabrication process of self-assembled carbon aerogels (graphene and carbon nanotube aerogels) is covered and the suggested mechanism for the gelation process of self-assembled carbon aerogels during the reduction process is investigated using reported mechanisms. The structural performance and functional properties (electrochemical and thermal properties) of different types of carbon aerogels are covered in detail. Moreover, different structural features of carbon aerogels and the influence of synthesis conditions on these structural characteristics are assessed and compared. Based on the literature results covered in this review paper, carbon aerogels are perfect candidates for the fabrication of ultra-low density supercapacitors, as well as thermal insulating materials.

  4. Self-assembled and pyrolyzed carbon aerogels: an overview of their preparation mechanisms, properties and applications.

    PubMed

    Allahbakhsh, Ahmad; Bahramian, Ahmad Reza

    2015-09-14

    An overview of the synthesis conditions and mechanisms for the fabrication of different types of carbon aerogels, as well as the structural and functional properties of these materials, is presented here. In this overview, carbon aerogels are classified into three major categories: (i) conventional pyrolyzed organic-based carbon aerogels, which are products of the pyrolysis process of organic aerogels; (ii) self-assembled carbon aerogels, which are products of a reduction process; and (iii) nanocomposite carbon aerogels. Synthesis mechanisms for the sol-gel process of organic aerogels are reviewed using different mechanisms suggested in the literature. Moreover, the overall fabrication process of self-assembled carbon aerogels (graphene and carbon nanotube aerogels) is covered and the suggested mechanism for the gelation process of self-assembled carbon aerogels during the reduction process is investigated using reported mechanisms. The structural performance and functional properties (electrochemical and thermal properties) of different types of carbon aerogels are covered in detail. Moreover, different structural features of carbon aerogels and the influence of synthesis conditions on these structural characteristics are assessed and compared. Based on the literature results covered in this review paper, carbon aerogels are perfect candidates for the fabrication of ultra-low density supercapacitors, as well as thermal insulating materials. PMID:26245296

  5. Thermal conductivity of a ZnO nanowire/silica aerogel nanocomposite

    NASA Astrophysics Data System (ADS)

    Xie, Jing; Frachioni, Anthony; Williams, D. S.; White, B. E.

    2013-05-01

    The thermal conductivity of 100 nm zinc oxide nanowires embedded in silica aerogel was measured using the 3ω method over a temperature range of 150 K to 300 K. Compared to 100 nm ZnO nanowires alone, the thermal conductivity of the nanocomposite was reduced by over an order of magnitude throughout this temperature range. We attribute this reduction to the scattering of ballistic phonons at the nanowire surface and the subsequent emission of and transport of energy by the scattered phonon into the silica aerogel, as predicted by the diffuse mismatch model.

  6. Aerogel Derived Nanostructured Thermoelectric Materials

    SciTech Connect

    Wendell E Rhine, PI; Dong, Wenting; Greg Caggiano, PM

    2010-10-08

    America’s dependence on foreign sources for fuel represents a economic and security threat for the country. These non renewable resources are depleting, and the effects of pollutants from fuels such as oil are reaching a problematic that affects the global community. Solar concentration power (SCP) production systems offer the opportunity to harness one of the United States’ most under utilized natural resources; sunlight. While commercialization of this technology is increasing, in order to become a significant source of electricity production in the United States the costs of deploying and operating SCP plants must be further reduced. Parabolic Trough SCP technologies are close to meeting energy production cost levels that would raise interest in the technology and help accelerate its adoption as a method to produce a significant portion of the Country’s electric power needs. During this program, Aspen Aerogels will develop a transparent aerogel insulation that can replace the costly vacuum insulation systems that are currently used in parabolic trough designs. During the Phase I program, Aspen Aerogels will optimize the optical and thermal properties of aerogel to meet the needs of this application. These properties will be tested, and the results will be used to model the performance of a parabolic trough HCE system which uses this novel material in place of vacuum. During the Phase II program, Aspen Aerogels will scale up this technology. Together with industry partners, Aspen Aerogels will build and test a prototype Heat Collection Element that is insulated with the novel transparent aerogel material. This new device will find use in parabolic trough SCP applications.

  7. Electrically insulated MLI and thermal anchor

    SciTech Connect

    Kamiya, Koji; Furukawa, Masato; Murakami, Haruyuki; Kizu, Kaname; Tsuchiya, Katsuhiko; Koidea, Yoshihiko; Yoshida, Kiyoshi; Hatakenaka, Ryuta; Miyakita, Takeshi

    2014-01-29

    The thermal shield of JT-60SA is kept at 80 K and will use the multilayer insulation (MLI) to reduce radiation heat load to the superconducting coils at 4.4 K from the cryostat at 300 K. Due to plasma pulse operation, the MLI is affected by eddy current in toroidal direction. The MLI is designed to suppress the current by electrically insulating every 20 degree in the toroidal direction by covering the MLI with polyimide films. In this paper, two kinds of designs for the MLI system are proposed, focusing on a way to overlap the layers. A boil-off calorimeter method and temperature measurement has been performed to determine the thermal performance of the MLI system. The design of the electrical insulated thermal anchor between the toroidal field (TF) coil and the thermal shield is also explained.

  8. Aerogel Development

    NASA Technical Reports Server (NTRS)

    Sahai, Rashmi K.

    2005-01-01

    Aerogel is one of the most promising materials of the future. It's unique properties, including high porosity, transparency, very high thermal tolerance, and environmental friendliness give it the potential of replacing many different products used in society today. However, the market for aerogel is still very limited because of the cost of producing the material and its fragility. The principle objective of my project has been to find new ways to apply aerogel in order to increase its practicality and appeal to different aspects of society. More specifically, I have focused on finding different chemicals that will coat aerogel and increase its durability. Because aerogel is so fragile and will crumble under the pressure of most coatings this has been no easy task. However, by experimenting with many different coatings and combinations of aerogel properties, I have made several significant discoveries. Aerogel (ideally, high density and hydrophobic) can be coated with several acrylic polymers, including artist's gel and nail polish. These materials provide a protective layering around the aerogel and keep it from breaking as easily. Because fragility is one of the main reasons applications of aerogel are limited, these discoveries will hopefully aid in finding future applications for this extraordinary material.

  9. Internally insulated thermal storage system development program

    NASA Technical Reports Server (NTRS)

    Scott, O. L.

    1980-01-01

    A cost effective thermal storage system for a solar central receiver power system using molten salt stored in internally insulated carbon steel tanks is described. Factors discussed include: testing of internal insulation materials in molten salt; preliminary design of storage tanks, including insulation and liner installation; optimization of the storage configuration; and definition of a subsystem research experiment to demonstrate the system. A thermal analytical model and analysis of a thermocline tank was performed. Data from a present thermocline test tank was compared to gain confidence in the analytical approach. A computer analysis of the various storage system parameters (insulation thickness, number of tanks, tank geometry, etc.,) showed that (1) the most cost-effective configuration was a small number of large cylindrical tanks, and (2) the optimum is set by the mechanical constraints of the system, such as soil bearing strength and tank hoop stress, not by the economics.

  10. 14 CFR 25.856 - Thermal/Acoustic insulation materials.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Thermal/Acoustic insulation materials. 25....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the.../acoustic insulation materials (including the means of fastening the materials to the fuselage) installed...

  11. 14 CFR 25.856 - Thermal/Acoustic insulation materials.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 14 Aeronautics and Space 1 2011-01-01 2011-01-01 false Thermal/Acoustic insulation materials. 25....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the.../acoustic insulation materials (including the means of fastening the materials to the fuselage) installed...

  12. 14 CFR 25.856 - Thermal/Acoustic insulation materials.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Thermal/Acoustic insulation materials. 25....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the.../acoustic insulation materials (including the means of fastening the materials to the fuselage) installed...

  13. 14 CFR 25.856 - Thermal/Acoustic insulation materials.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Thermal/Acoustic insulation materials. 25....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the.../acoustic insulation materials (including the means of fastening the materials to the fuselage) installed...

  14. 14 CFR 25.856 - Thermal/Acoustic insulation materials.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Thermal/Acoustic insulation materials. 25....856 Thermal/Acoustic insulation materials. (a) Thermal/acoustic insulation material installed in the.../acoustic insulation materials (including the means of fastening the materials to the fuselage) installed...

  15. Nuclear reactor vessel fuel thermal insulating barrier

    SciTech Connect

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

    2013-03-19

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

  16. Multilayer Impregnated Fibrous Thermal Insulation Tiles

    NASA Technical Reports Server (NTRS)

    Tran, Huy K.; Rasky, Daniel J.; Szalai, Christine e.; Hsu, Ming-ta; Carroll, Joseph A.

    2007-01-01

    The term "secondary polymer layered impregnated tile" ("SPLIT") denotes a type of ablative composite-material thermal- insulation tiles having engineered, spatially non-uniform compositions. The term "secondary" refers to the fact that each tile contains at least two polymer layers wherein endothermic reactions absorb considerable amounts of heat, thereby helping to prevent overheating of an underlying structure. These tiles were invented to afford lighter-weight alternatives to the reusable thermal-insulation materials heretofore variously used or considered for use in protecting the space shuttles and other spacecraft from intense atmospheric-entry heating.

  17. Preparation of Biopolymer Aerogels Using Green Solvents.

    PubMed

    Subrahmanyam, Raman; Gurikov, Pavel; Meissner, Imke; Smirnova, Irina

    2016-01-01

    Although the first reports on aerogels made by Kistler(1) in the 1930s dealt with aerogels from both inorganic oxides (silica and others) and biopolymers (gelatin, agar, cellulose), only recently have biomasses been recognized as an abundant source of chemically diverse macromolecules for functional aerogel materials. Biopolymer aerogels (pectin, alginate, chitosan, cellulose, etc.) exhibit both specific inheritable functions of starting biopolymers and distinctive features of aerogels (80-99% porosity and specific surface up to 800 m(2)/g). This synergy of properties makes biopolymer aerogels promising candidates for a wide gamut of applications such as thermal insulation, tissue engineering and regenerative medicine, drug delivery systems, functional foods, catalysts, adsorbents and sensors. This work demonstrates the use of pressurized carbon dioxide (5 MPa) for the ionic cross linking of amidated pectin into hydrogels. Initially a biopolymer/salt dispersion is prepared in water. Under pressurized CO2 conditions, the pH of the biopolymer solution is lowered to 3 which releases the crosslinking cations from the salt to bind with the biopolymer yielding hydrogels. Solvent exchange to ethanol and further supercritical CO2 drying (10 - 12 MPa) yield aerogels. Obtained aerogels are ultra-porous with low density (as low as 0.02 g/cm(3)), high specific surface area (350 - 500 m(2)/g) and pore volume (3 - 7 cm(3)/g for pore sizes less than 150 nm). PMID:27403649

  18. Carbon aerogel composites prepared by ambient drying and using oxidized polyacrylonitrile fibers as reinforcements.

    PubMed

    Feng, Junzong; Zhang, Changrui; Feng, Jian; Jiang, Yonggang; Zhao, Nan

    2011-12-01

    Carbon fiber-reinforced carbon aerogel composites (C/CAs) for thermal insulators were prepared by copyrolysis of resorcinol-formaldehyde (RF) aerogels reinforced by oxidized polyacrylonitrile (PAN) fiber felts. The RF aerogel composites were obtained by impregnating PAN fiber felts with RF sols, then aging, ethanol exchanging, and drying at ambient pressure. Upon carbonization, the PAN fibers shrink with the RF aerogels, thus reducing the difference of shrinkage rates between the fiber reinforcements and the aerogel matrices, and resulting in C/CAs without any obvious cracks. The three point bend strength of the C/CAs is 7.1 ± 1.7 MPa, and the thermal conductivity is 0.328 W m(-1) K(-1) at 300 °C in air. These composites can be used as high-temperature thermal insulators (in inert atmospheres or vacuum) or supports for phase change materials in thermal protection system. PMID:22047011

  19. Mechanically Strong Lightweight Materials for Aerospace Applications (x-aerogels)

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas

    2005-01-01

    The X-Aerogel is a new NASA-developed strong lightweight material made by reacting the mesoporous surfaces of 3-D networks of inorganic nanoparticles with polymeric crosslinkers. Since the relative amount of the crosslinker and the backbone are comparable, X-Aerogels can be viewed either as aerogels modified by templated accumulation of polymer on the skeletal nanoparticles, or as nanoporous polymers made by templated casting of polymeric precursors on a nanostructured framework. The most striking feature of X-Aerogels is that for a nominal 3-fold increase in density (still a ultralightweight material), the mechanical strength can be up to 300 times higher than the strength of the underlying native aerogel. Thus, X-Aerogels combine a multiple of the specific compressive strength of steel, with the thermal conductivity of styrofoam. XAerogels have been demonstrated with several polymers such as polyurethanes/polyureas, epoxies and polyolefins, while crosslinking of approximately 35 different oxide aerogels yields a wide variety of dimensionally stable, porous lightweight materials with interesting structural, magnetic and optical properties. X-Aerogels are evaluated for cryogenic rocket fuel storage tanks and for Advanced EVA suits, where they will play the dual role of the thermal insulator/structural material. Along the same lines, major impact is also expected by the use of X-Aerogels in structural components/thermal protection for small satellites, spacecrafts, planetary vehicles and habitats.

  20. Silica/Polymer and Silica/Polymer/Fiber Composite Aerogels

    NASA Technical Reports Server (NTRS)

    Ou, Danny; Stepanian, Christopher J.; Hu, Xiangjun

    2010-01-01

    Aerogels that consist, variously, of neat silica/polymer alloys and silica/polymer alloy matrices reinforced with fibers have been developed as materials for flexible thermal-insulation blankets. In comparison with prior aerogel blankets, these aerogel blankets are more durable and less dusty. These blankets are also better able to resist and recover from compression . an important advantage in that maintenance of thickness is essential to maintenance of high thermal-insulation performance. These blankets are especially suitable as core materials for vacuum- insulated panels and vacuum-insulated boxes of advanced, nearly seamless design. (Inasmuch as heat leakage at seams is much greater than heat leakage elsewhere through such structures, advanced designs for high insulation performance should provide for minimization of the sizes and numbers of seams.) A silica/polymer aerogel of the present type could be characterized, somewhat more precisely, as consisting of multiply bonded, linear polymer reinforcements within a silica aerogel matrix. Thus far, several different polymethacrylates (PMAs) have been incorporated into aerogel networks to increase resistance to crushing and to improve other mechanical properties while minimally affecting thermal conductivity and density. The polymethacrylate phases are strongly linked into the silica aerogel networks in these materials. Unlike in other organic/inorganic blended aerogels, the inorganic and organic phases are chemically bonded to each other, by both covalent and hydrogen bonds. In the process for making a silica/polymer alloy aerogel, the covalent bonds are introduced by prepolymerization of the methacrylate monomer with trimethoxysilylpropylmethacrylate, which serves as a phase cross-linker in that it contains both organic and inorganic monomer functional groups and hence acts as a connector between the organic and inorganic phases. Hydrogen bonds are formed between the silanol groups of the inorganic phase and the

  1. Thermal/acoustical aircraft insulation material

    NASA Technical Reports Server (NTRS)

    Struzik, E. A.; Kunz, R.; Lin, R.

    1975-01-01

    Attempts made to improve the acoustical properties of low density Fiberfrax foam, an aircraft insulation material, are reported. Characterizations were also made of the physical and thermal properties. Two methods, optimization of fiber blend composition and modification of the foam fabrication process, were examined as possible means of improving foam acoustics. Flame impingement tests were also made; results show performance was satisfactory.

  2. Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide.

    PubMed

    Wicklein, Bernd; Kocjan, Andraž; Salazar-Alvarez, German; Carosio, Federico; Camino, Giovanni; Antonietti, Markus; Bergström, Lennart

    2015-03-01

    High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m(-1) K(-1), which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials. PMID:25362476

  3. Thermally insulating and fire-retardant lightweight anisotropic foams based on nanocellulose and graphene oxide

    NASA Astrophysics Data System (ADS)

    Wicklein, Bernd; Kocjan, Andraž; Salazar-Alvarez, German; Carosio, Federico; Camino, Giovanni; Antonietti, Markus; Bergström, Lennart

    2015-03-01

    High-performance thermally insulating materials from renewable resources are needed to improve the energy efficiency of buildings. Traditional fossil-fuel-derived insulation materials such as expanded polystyrene and polyurethane have thermal conductivities that are too high for retrofitting or for building new, surface-efficient passive houses. Tailored materials such as aerogels and vacuum insulating panels are fragile and susceptible to perforation. Here, we show that freeze-casting suspensions of cellulose nanofibres, graphene oxide and sepiolite nanorods produces super-insulating, fire-retardant and strong anisotropic foams that perform better than traditional polymer-based insulating materials. The foams are ultralight, show excellent combustion resistance and exhibit a thermal conductivity of 15 mW m-1 K-1, which is about half that of expanded polystyrene. At 30 °C and 85% relative humidity, the foams retained more than half of their initial strength. Our results show that nanoscale engineering is a promising strategy for producing foams with excellent properties using cellulose and other renewable nanosized fibrous materials.

  4. Thermal insulating coating for spacecrafts

    NASA Technical Reports Server (NTRS)

    Kaul, Raj K. (Inventor)

    2005-01-01

    To protect spacecraft and their contents from excessive heat thermal protection systems are essential. For such thermal protection, metal coatings, ceramic materials, ablative materials, and various matrix materials have all been tried, but none have been found entirely satisfactory. The basis for this thermal protection system is the fact that the heat required to melt a substance is 80 to 100 times larger than the heat required to raise its temperature one degree. This led to the use herein of solid-liquid phase change materials. Unlike conventional heat storage materials, when phase change materials reach the temperature at which they change phase they absorb large amounts of heat without getting hotter. By this invention, then, a coating composition is provided for application to substrates subjected to temperatures above 100? F. The coating composition includes a phase change material.

  5. Thermal Insulating Coating for Spacecrafts

    NASA Technical Reports Server (NTRS)

    Kaul, Raj K. (Inventor)

    2005-01-01

    To protect spacecraft and their contents from excessive heat thermal protection system are essential. For such thermal protection, metal coatings, ceramic materials, ablative materials, and various matrix materials have all been tried, but none have been found entirely satisfactory. The basis for this thermal protection system is the fact that the heat required to melt a substance is 80 to 100 times larger than the heat required to raise its temperature one degree. This led to the use herein of solid-liquid phase change materials. Unlike conventional heat storage materials, when phase change materials reach the temperature at which they change phase they absorb large amounts of heat without getting hotter. By this invention, then, a coating composition is provided for application to substrates subjected to temperatures above 100 F. The coating composition includes a phase change material.

  6. Polyimide Cellulose Nanocrystal Composite Aerogels

    NASA Technical Reports Server (NTRS)

    Nguyen, Baochau N.; Meador, Mary Ann; Rowan, Stuart; Cudjoe, Elvis; Sandberg, Anna

    2014-01-01

    Polyimide (PI) aerogels are highly porous solids having low density, high porosity and low thermal conductivity with good mechanical properties. They are ideal for various applications including use in antenna and insulation such as inflatable decelerators used in entry, decent and landing operations. Recently, attention has been focused on stimuli responsive materials such as cellulose nano crystals (CNCs). CNCs are environmentally friendly, bio-renewable, commonly found in plants and the dermis of sea tunicates, and potentially low cost. This study is to examine the effects of CNC on the polyimide aerogels. The CNC used in this project are extracted from mantle of a sea creature called tunicates. A series of polyimide cellulose nanocrystal composite aerogels has been fabricated having 0-13 wt of CNC. Results will be discussed.

  7. Organic aerogel microspheres

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1999-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  8. Organic aerogel microspheres

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1999-06-01

    Organic aerogel microspheres are disclosed which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonstick gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  9. Effective Thermal Conductivity of Corrugated Insulating Materials

    NASA Astrophysics Data System (ADS)

    Yamada, Etsuro; Kato, Masayasu; Tomikawa, Takayuki; Takahashi, Kaneko

    The effective thermal conductivity of corrugated insulating materials which are made by polypropylene or polycarbonate have been measured by employing steady state comparison method for several specimen having various thickness and specific weight. The thermal conductivity of them evaluated are also by using the thermal resistance models, and are compared with above measured values and raw materials' conductivity. The main results obtained in this paper are as follows: (1) In regard to the specimen in this paper, the effective thermal conductivity increases with increasing temperature, but the increasing rate of them is small. (2) There are considerable differences between the measured values and the predicted ones that are estimated by using the thermal resistance model in which heat flow by conduction only. This differences increase with increasing specimens' thickness. This difference become extinct by considering the coexistence heat flow of conduction and radiation in the air phase of specimen. (3) The thermal resistance of specimen increases linearly with increasing specimens' thickness.

  10. Aerogel/Particle Composites for Thermoelectric Devices

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Sakamoto, Jeffrey; Jones, Steven

    2006-01-01

    Optimizing solution chemistry and the addition of titania and fumed silica powder reduces shrinkage. These materials would serve to increase thermal efficiency by providing thermal insulation to suppress lateral heat leaks. They would also serve to prolong operational lifetime by suppressing sublimation of certain constituents of thermoelectric materials (e.g., sublimation of Sb from CoSb3) at typical high operating temperatures. [The use of pure silica aerogels as cast-in-place thermal-insulation and sublimation-suppression materials was described in "Aerogels for Thermal Insulation of Thermoelectric Devices" (NPO-40630), NASA Tech Briefs, Vol. 30, No. 7 (July 2006), page 50.] A silica aerogel is synthesized in a solgel process that includes preparation of a silica sol, gelation of the sol, and drying of the gel in a solvent at a supercritical temperature and pressure. The utility of pure silica aerogel is diminished by a tendency to shrink (and, therefore, also to crack) during the gelation and supercritical-drying stages. Moreover, to increase suppression of sublimation, it is advantageous to make an aerogel having greater density, but shrinkage and cracking tend to increase with density. A composite material of the type under investigation consists mostly of titania oxide powder particles and a small addition of fumed silica powder, which are mixed into the sol along with other ingredients prior to the gelation stage of processing. The silica aerogel and fumed silica act as a binder, gluing the titania particles together. It is believed that the addition of fumed silica stiffens the aerogel network and reduces shrinkage during the supercritical-drying stage. Minimization of shrinkage enables establishment of intimate contact between thermoelectric legs and the composite material, thereby maximizing the effectiveness of the material for thermal insulation and suppression of sublimation. To some extent, the properties of the composite can be tailored via the

  11. Thermal insulation of materials with possible aerospace application.

    PubMed

    Kaufman, W C; Bothe, D J

    1986-10-01

    Thermal insulation values for several materials that may have aerospace applications have been determined by a single method. Heat transfer across a specimen on a constant temperature heat source was measured by heat flow disc, and temperature on each side of the specimen was measured by thermistor. The data demonstrate that, with various thermal insulating materials, the primary factor in thermal insulation is the entrapped air. Where convective air currents were sufficiently reduced, insulative values for different materials varied only slightly. Reflective and nonreflective materials sandwiched into the insulators made little difference in these experiments, but if employed differently, might increase insulative values significantly. PMID:3778398

  12. Smoldering combustion hazards of thermal insulation materials

    SciTech Connect

    Ohlemiller, T.J.; Rogers, F.E.

    1980-07-01

    Work on the smolder ignitability in cellulosic insulation and on thermal analytical characterization of the oxidation of this material is presented. Thermal analysis (TGA and DSC) shows that both retarded and unretarded cellulosic insulation oxidizes in two overall stages, both of which are exothermic. The second stage (oxidation of the char left as a residue of the first stage) is much more energetic on a unit mass basis than the first. However, kinetics and a sufficient exothermicity make the first stage responsible for ignition in most realistic circumstances. Existing smolder retardants such as boric acid have their major effect on the kinetics of the second oxidation stage and thus produce only a rather small (20/sup 0/C) increase in smolder ignition temperature. Several simplified analogs of attic insulations have been tested to determine the variability of minimum smolder ignition temperature. These employed planar or tubular constant temperature heat sources in a thermal environment quite similar to a realistic attic application. Go/no-go tests provided the borderline (minimum) ignition temperature for each configuration. The wide range (150/sup 0/C) of minimum ignition temperatures confirmed the predominant dependence of smolder ignition on heat flow geometry. Other factors (bulk density, retardants) produced much less effect on ignitability.

  13. Clay Nanocomposite/Aerogel Sandwich Structures for Cryotanks

    NASA Technical Reports Server (NTRS)

    Miller, Sandi; Leventis, Nicholas; Johnston, J. Chris; Meador, Michael

    2006-01-01

    GRC research has led to the development of epoxy-clay nanocomposites with 60-70% lower gas permeability than the base epoxy resin. Filament wound carbon fiber reinforced tanks made with this nanocomposite had a five-fold lower helium leak rate than the corresponding tanks made without clay. More recent work has produced new composites with more than a 100-fold reduction in helium permeability. Use of these advanced, high barrier composites would eliminate the need for a liner in composite cryotanks, thereby simplifying construction and reducing propellant leakage. Aerogels are attractive materials for use as cryotank insulation because of their low density and low thermal conductivity. However, aerogels are fragile and have poor environmental stability, which have limited their use to certain applications in specialized environments (e.g., in certain types of nuclear reactors as Cerenkov radiation detectors, and as thermal insulators aboard space rovers on Mars). New GRC developed polymer crosslinked aerogels (X-Aerogels) retain the low density of conventional aerogels, but they demonstrate a 300-fold increase in their mechanical strength. Currently, our strongest materials combine a density of approx. 0.45 g/cc, a thermal conductivity of approx. 0.04 W/mK and a compressive strength of 185 MPa. Use of these novel aerogels as insulation materials/structural components in combination with the low permeability of epoxy-clay nanocomposites could significantly reduce cryotank weight and improve durability.

  14. Ceramic-Fibrous-Insulation Thermal-Protection System

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel; Churchward, Rex; Katvala, Victor; Stewart, David; Balter, Aliza

    1992-01-01

    New composite thermal-protection system developed in which glass-ceramic impregnated into surface of fibrous insulation. Called TUFI for toughened unipiece fibrous insulation developed as replacement for tiles with reaction-cured-glass (RCG) coating. Impregnation of glass-ceramic results in thermal protection system with insulating properties comparable to existing system but with 20 to 100 times more resistance to impact.

  15. Flat-plate boiloff calorimeters for testing of thermal insulation systems

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Johnson, W. L.; Kelly, A. O.; Meneghelli, B. J.; Swanger, A. M.

    2015-12-01

    Cryostats have been developed and standardized for laboratory testing of thermal insulation systems in a flat-plate configuration. Boiloff calorimetry is the measurement principle for determining the effective thermal conductivity (ke) and heat flux (q) of test specimens under a wide range of actual conditions. Cryostat-500 is thermally guarded to measure absolute thermal performance when calibrated with a known reference via an adjustable-edge guard ring. With liquid nitrogen as the energy meter, the cold boundary temperature can be adjusted to any temperature between 77 K and approximately 300 K by the interposition of a thermal resistance layer between the cold mass and the specimen. A low thermal conductivity suspension system has compliance rods that adjust for specimen thickness and compression force. Material type, thickness, density, flatness, compliance, outgassing, and temperature sensor placement are important test considerations, and edge effects and calibration techniques for the apparatus are crucial. Over the full vacuum pressure range, the thermal performance capability is nearly four orders of magnitude. The horizontal configuration provides key advantages over the vertical cylindrical cryostats for testing at ambient pressure conditions. Cryostat-500’s design and test methods, other flat-plate boiloff calorimeters, and results for select thermal insulation materials (composites, foams, aerogels) are discussed.

  16. Blowable glass fiber thermal insulation product

    SciTech Connect

    Spittle, K.S.

    1984-10-09

    A process and apparatus for manufacturing a blowable glass fiber insulation product is disclosed. The product resulting from the process and apparatus is also disclosed. This process includes the steps of cutting unbonded glass fiber matting and lengths of twisted glass fiber yarn raw material into predetermined relatively large size pieces. The pieces are mixed together and the mixture is fluffed to decrease its density. The mixture is then hammermilled into relatively smaller size pieces suitable for use as blowable insulation. In accordance with the apparatus according to this invention, a cutter cuts glass fiber matting and lengths of twisted glass fiber yarn into relatively large size pieces which are mixed and then fluffed and further cut in a fluffer. A hammermill is used for reducing the mixture into relatively smaller size pieces suitable for use as blowable insulation. The blowable insulation product comprises loose, irregularly formed and separate clumps of glass fiber material approximately one inch (215 cm.) in diameter and having a density of 1 lb./cu./ft. (16 kg./cu./m.) and has a thermal resistance value of 3.3 per inch (2.5 cm.) of thickness.

  17. Apparatus for Testing Flat Specimens of Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, Stanislaw D.

    2005-01-01

    around the specimen (see figure). A spring-based compensating fixture helps to ensure adequate thermal contact with possibly irregular specimen surfaces. For a high-compression test, the springs can be replaced with spacers. A flat circular load cell at the bottom of the chamber measures the compressive load on the specimen. Once the desired compressive-load, temperature, and vacuum/gas-filling conditions are established, testing begins. During a test, all measurements are recorded by use of a portable data-acquisition system and a computer. The total heat-leak rate is measured and calculated as the boil-off flow rate multiplied by the latent heat of vaporization. The parasitic heat leak (to the side of the specimen and to the top and side of the cold-mass tank) is reduced to a small fraction of the total heat leak by use of a combination of multilayer-insulation (MLI) shield rings, reflective film, a fiberglass/epoxy centering ring, and a bulk fill of aerogel beads. This combination eliminates the need for a cryogenic guard chamber used in a typical prior apparatus to reduce the parasitic heat leak.

  18. Effect of Cyclic Aeroconvective Heating on Flexible Thermal Insulations

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Zambrano, Brian; Kowalski, Tom; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    This paper describes the effect of cyclic aeroconvective heating on the thermal performance of ceramic flexible insulations considered for potential use as thermal protection systems or thermal insulations for future hypersonic vehicles such as the Reusable Launch Vehicles (RLV's) and other applications where structures require thermal protection from severe heating. The thermal response of these materials after exposure to cyclic aeroconvective heating from a plasma arc is described. The thermal insulations evaluated were Composite Flexible Blanket Insulations composed of an outer layer of aluminoborosilicate fabric and alumina insulation. The insulations were evaluated with and without a high emissivity coating. These insulations were exposed to the plasma arc stream for nine minutes reaching surface temperatures of 1150 C and a heat flux of 10.5 W/sq cm. Insulations were exposed three, six, or nine times in order to demonstrate reusability and to determine the effect oi coatings on the surface durability of these insulations. Test results demonstrated the capability of these insulations to protect either composite or metallic structures from high heating environments. It is shown that high emittance coatings reduce backface temperatures. The durability of these insulations when impacted at low velocities was also demonstrated. The interaction of the coatings with the ceramic fibers was characterized. An analytical thermal model was utilized to correlate experimental thermal test results with calculated values.

  19. Resorcinol-formaldehyde and carbon aerogel microspheres

    SciTech Connect

    Alviso, C.T.; Pekela, R.W.; Gross, J.; Lu, X.; Caps, R.; Fricke, J

    1996-04-01

    Aerogels are a unique class of materials possessing an open-cell structure with ultrafine cells/pores (<100nm), high surface area (400--1100 m{sup 2}/g), and a solid matrix composed of interconnected particles, fibers, or platelets with characteristic dimensions of 10nm. Although monolithic aerogels are ideal candidates for many applications (e.g. transparent window insulation), current processing methods have limited their introduction into the commercial marketplace. Our research focuses on the formation of resorcinol-formaldehyde (RF) aerogel microspheres which offer an attractive alternative to monolith production. An inverse emulsion polymerization is used to produce these spherical gel particles which undergo solvent exchange followed by supercritical drying with carbon dioxide. This process yields aerogel microspheres (10--80{mu} diameter) which can be used as loosely packed powders, compression molded into near-net shapes using a polymer binder, or used as additives in conventional foaming operations to produce new aerogel composites with superior thermal properties. The emulsification procedure, thermal characterization, mechanical properties, and potential applications of RF aerogel microspheres will be discussed.

  20. Composite flexible insulation for thermal protection of space vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Tran, Huy K.; Chiu, S. Amanda

    1991-01-01

    A composite flexible blanket insulation (CFBI) system considered for use as a thermal protection system for space vehicles is described. This flexible composite insulation system consists of an outer layer of silicon carbide fabric, followed by alumina mat insulation, and alternating layers of aluminized polyimide film and aluminoborosilicate scrim fabric. A potential application of this composite insulation would be as a thermal protection system for the aerobrake of the aeroassist space transfer vehicle (ASTV). It would also apply to other space vehicles subject to high convective and radiative heating during atmospheric entry. The thermal performance of this composite insulation as exposed to a simulated atmospheric entry environment in a plasma arc test facility is described. Other thermophysical properties which affect the thermal response of this composite insulation is included. It shows that this composite insulation is effective as a thermal protection system at total heating rates up to 30.6 W/sq cm.

  1. Cryogenic Insulation Systems

    NASA Technical Reports Server (NTRS)

    Augustynowicz, S. D.; Fesmire, J. E.; Wikstrom, J. P.

    1999-01-01

    The results of a comparative study of cryogenic insulation systems performed are presented. The key aspects of thermal insulation relative to cryogenic system design, testing, manufacturing, and maintenance are discussed. An overview of insulation development from an energy conservation perspective is given. Conventional insulation materials for cryogenic applications provide three levels of thermal conductivity. Actual thermal performance of standard multilayer insulation (MLI) is several times less than laboratory performance and often 10 times worse than ideal performance. The cost-effectiveness of the insulation system depends on thermal performance; flexibility and durability; ease of use in handling, installation, and maintenance; and overall cost including operations, maintenance, and life cycle. Results of comprehensive testing of both conventional and novel materials such as aerogel composites using cryostat boil-off methods are given. The development of efficient, robust cryogenic insulation systems that operate at a soft vacuum level is the primary focus of this paper.

  2. Morphology effects on electrical and thermal properties of binderless graphene aerogels

    NASA Astrophysics Data System (ADS)

    Fan, Zeng; Tng, Daniel Zhi Yong; Nguyen, Son Truong; Feng, Jingduo; Lin, Chunfu; Xiao, Pengfei; Lu, Li; Duong, Hai M.

    2013-03-01

    Three-dimensional self-assembled graphene aerogels (GAs) are successfully developed by a simple chemical reduction with L-ascorbic acid at low temperature. And for the first time, the relationship among morphologies, electrical and thermal properties of GAs is studied comprehensively by controlling reaction conditions. The electrical conductivities of the GAs are also improved by four times after an annealing at 400 °C for 5 h under Ar environment. The results are very useful to optimize the best morphology, electrical and thermal properties of GAs for the best performance of GA-based electrodes of energy storage devices such as supercapacitors and batteries.

  3. New methods of characterizing the thermal properties of silica aerogel/xerogel

    NASA Astrophysics Data System (ADS)

    Stangl, R.; Platzer, Werner J.; Wittwer, Volker

    1994-09-01

    Integral as well as spectral methods to characterize the thermal properties of Silica Aerogel and Xerogel samples are presented. A new method to determine the effective thermal conductivity with the help of an infrared camera was developed, which allows for measuring small samples. Keeping the lower surface of the samples at a constant temperature, the IR camera monitors the upper surface temperature. With the help of a reference sample of known thermal conductivity, the total heat flux through the samples can be calculated. This is done under different pressure conditions in order to observe the Knudsen effect. As there is a complex coupling between the different modes of heat transport, the spectrum of the emitted radiation is of interest. Emission spectroscopy on Silica Aerogel has not been previously investigated in detail. An emission chamber was constructed, which permits measuring of the emitted spectra due to an applied temperature gradient using a Perkin Elmer Infrared Grating spectrometer. Different boundary emissivities and varying pressure conditions can be applied. For a correct interpretation of the measured spectra, a numerical treatment of the underlying heat transport mechanism is necessary. Measurements as well as computer simulations are presented. Computer simulations show that a variation of the total thermal conductivity in the range between 1 mW/mK and 30 mW/mK leads to a characteristic damping of the emitted radiation between 500 cm-1 and 2000 cm-1. This characteristic damping of the emitted radiation can be observed by measuring the emitted spectra of Silica Aerogel/Xerogel at varying pressure conditions. Therefore, in principle, it should be possible to extract the thermal conductivity through the gas pores and through the silica skeleton. Boundary effects, however, prevent this data from being extracted. Hopefully these problems will be solved in the near future.

  4. System for Testing Thermal Insulation of Pipes

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, Stanislaw D.; Nagy, Zoltan F.

    2003-01-01

    An apparatus and method have been developed for measuring the rates of leakage of heat into pipes carrying liquids, the purpose of the measurements being to quantify the thermal performance of the insulation system. The apparatus is designed primarily for testing pipes used to carry cryogenic liquids, but can also be used for measuring the thermal performance of other insulated pipes or piping systems. The basic measurement principle is straightforward: The outer surface of the pipe insulation is maintained at a fixed warmer temperature. The interior of the pipe is maintained in a narrow fixed lower-temperature range by means of a regular liquid (e.g., water) that is pumped through the pipe at a known flow rate or a cryogenic liquid (e.g., nitrogen) that is saturated at atmospheric pressure and replenished until steady-state conditions are achieved. In the case of water or another liquid pumped through, the inlet and outlet temperatures are measured and heat-leak power is calculated as the mass flow rate of the liquid multiplied by the specific heat of the liquid multiplied by the inlet-to-outlet temperature rise of the liquid. In the case of liquid nitrogen or another low-temperature boiling liquid, the heat-leak power is calculated as the rate of boil-off multiplied by the latent heat of vaporization of the liquid. Then the thermal-insulation performance of the pipe system can be calculated as a function of the measured heat-leak power, the inner and outer boundary temperatures, and the dimensions of the pipe. The apparatus can test as many as three pipes simultaneously. The pipes can have inner diameters up to .15 cm and outer diameters up to .20 cm. The lengths of the pipes may vary; typical lengths are of the order of 18 m. Two thermal guard boxes . one for each end of the pipe(s) under test . are used to make the inlet and outlet fluid connections to the pipe(s) (see figure). The connections include bellows that accommodate thermal expansion and contraction

  5. 14 CFR 23.856 - Thermal/acoustic insulation materials.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 14 Aeronautics and Space 1 2013-01-01 2013-01-01 false Thermal/acoustic insulation materials. 23.856 Section 23.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Construction Fire Protection § 23.856 Thermal/acoustic insulation materials. Thermal/acoustic...

  6. 14 CFR 23.856 - Thermal/acoustic insulation materials.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 14 Aeronautics and Space 1 2014-01-01 2014-01-01 false Thermal/acoustic insulation materials. 23.856 Section 23.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Construction Fire Protection § 23.856 Thermal/acoustic insulation materials. Thermal/acoustic...

  7. 14 CFR 23.856 - Thermal/acoustic insulation materials.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 14 Aeronautics and Space 1 2012-01-01 2012-01-01 false Thermal/acoustic insulation materials. 23.856 Section 23.856 Aeronautics and Space FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION... Construction Fire Protection § 23.856 Thermal/acoustic insulation materials. Thermal/acoustic...

  8. Carbon Nanofiber Incorporated Silica Based Aerogels with Di-Isocyanate Cross-Linking

    NASA Technical Reports Server (NTRS)

    Vivod, Stephanie L.; Meador, Mary Ann B.; Capadona, Lynn A.; Sullivan, Roy M.; Ghosn, Louis J.; Clark, Nicholas; McCorkle, Linda

    2008-01-01

    Lightweight materials with excellent thermal insulating properties are highly sought after for a variety of aerospace and aeronautic applications. (1) Silica based aerogels with their high surface area and low relative densities are ideal for applications in extreme environments such as insulators for the Mars Rover battery. (2) However, the fragile nature of aerogel monoliths prevents their widespread use in more down to earth applications. We have shown that the fragile aerogel network can be cross-linked with a di-isocyanate via amine decorated surfaces to form a conformal coating. (3) This coating reinforces the neck regions between secondary silica particles and significantly strengthens the aerogels with only a small effect on density or porosity. Scheme 1 depicts the cross-linking reaction with the di-isocyanate and exhibits the stages that result in polymer cross-linked aerogel monoliths.

  9. Operating temperatures of recessed fluorescent fixtures with thermal insulation

    SciTech Connect

    Yarbrough, D.W.; Toor, I.A.

    1981-05-01

    Tests were performed to determine steady state surface temperatures for recessed fluorescent fixtures operated with and without thermal insulation on the top side of the fixture and to identify potential problems associated with the installation of thermal insulation. In addition to measuring temperatures, means were sought by which the fixtures can be thermally insulated and operated without fire hazards or damage to the fixture. (MCW)

  10. Study on the thermal resistance in secondary particles chain of silica aerogel by molecular dynamics simulation

    SciTech Connect

    Liu, M.; Qiu, L. E-mail: jzzhengxinghua@163.com; Zheng, X. H. E-mail: jzzhengxinghua@163.com; Zhu, J.; Tang, D. W.

    2014-09-07

    In this article, molecular dynamics simulation was performed to study the heat transport in secondary particles chain of silica aerogel. The two adjacent particles as the basic heat transport unit were modelled to characterize the heat transfer through the calculation of thermal resistance and vibrational density of states (VDOS). The total thermal resistance of two contact particles was predicted by non-equilibrium molecular dynamics simulations (NEMD). The defects were formed by deleting atoms in the system randomly first and performing heating and quenching process afterwards to achieve the DLCA (diffusive limited cluster-cluster aggregation) process. This kind of treatment showed a very reasonable prediction of thermal conductivity for the silica aerogels compared with the experimental values. The heat transport was great suppressed as the contact length increased or defect concentration increased. The constrain effect of heat transport was much significant when contact length fraction was in the small range (<0.5) or the defect concentration is in the high range (>0.5). Also, as the contact length increased, the role of joint thermal resistance played in the constraint of heat transport was increasing. However, the defect concentration did not affect the share of joint thermal resistance as the contact length did. VDOS of the system was calculated by numerical method to characterize the heat transport from atomic vibration view. The smaller contact length and greater defect concentration primarily affected the longitudinal acoustic modes, which ultimately influenced the heat transport between the adjacent particles.

  11. Thermally Insulating, Kinematic Tensioned-Fiber Suspension

    NASA Technical Reports Server (NTRS)

    Voellmer, George M.

    2004-01-01

    A salt pill and some parts of a thermally insulating, kinematic suspension system that holds the salt pill rigidly in an adiabatic-demagnetization refrigerator (ADR) is presented. "Salt pill" in this context denotes a unit comprising a cylindrical container, a matrix of gold wires in the container, and a cylinder of ferric ammonium alum (a paramagnetic salt) that has been deposited on the wires. The structural members used in this system for both thermal insulation and positioning are aromatic polyamide fibers (Kevlar(R) or equivalent) under tension. This suspension system is designed to satisfy several special requirements to ensure the proper operation of the ADR. These requirements are to (1) maintain the salt pill at a specified position within the cylindrical bore of an electromagnet; (2) prevent vibrations, which would cause dissipation of heat in the salt pill; and (3) minimize the conduction of heat from the electromagnet bore and other neighboring objects to the salt pill; all while (4) protecting the salt pill (which is fragile) against all tensile and bending loads other than those attributable to its own weight. In addition, the system is required to consist of two subsystems -- one for the top end and one for the bottom end of the salt pill -- that can be assembled and tensioned separately from each other and from the salt pill, then later attached to the salt pill.

  12. Better Thermal Insulation in Solar-Array Laminators

    NASA Technical Reports Server (NTRS)

    Burger, D. R.; Knox, J. F.

    1984-01-01

    Glass marbles improve temperature control. Modified vacuum laminator for photovoltaic solar arrays includes thermal insulation made of conventional glass marbles. Marbles serve as insulation for temperature control of lamination process at cure temperatures as high as 350 degrees F. Used to replace original insulation made of asbestos cement.

  13. Pore morphology study of silica aerogels

    SciTech Connect

    Hua, D.W.; Anderson, J.; Haereid, S.; Smith, D.M.

    1994-12-31

    Silica aerogels have numerous properties which suggest applications such as ultra high efficiency thermal insulation. These properties relate directly to the aerogel`s pore size distribution. The micro and meso pore size ranges can be investigated by normal small angle x-ray scattering and possibly, nitrogen adsorption. However, the measurement of larger pores (> 250 {angstrom}) is more difficult. Due to their limited mechanical strength, mercury porosimetry and nitrogen condensation can disrupt the gel structure and electron microscopy provides only limited large scale structure information. The use of small angle light scattering techniques seems to have promise, the only hurdle is that aerogels exhibit significant multiple scattering. This can be avoided if one observes the gels in the wet stage since the structure of the aerogel should be very similar to the wet gel (as the result of supercritical drying). Thus, if one can match the refractive index, the morphology can be probed. The combination of certain alcoholic solvents fit this index matching criteria. Preliminary results for the gel network (micron range) and primary particle structure (manometer) are reported by using small angle light scattering and ultra-small angle x-ray scattering. The effects on structure over the length scale range of <1 nm to >5 {mu}m under different conditions (precursors, pH, etc.) are presented. The change in structure of an aerogel during isostatic compaction to 228 MPa (to simulate drying from wetting solvents) are also discussed.

  14. Treating Fibrous Insulation to Reduce Thermal Conductivity

    NASA Technical Reports Server (NTRS)

    Zinn, Alfred; Tarkanian, Ryan

    2009-01-01

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

  15. Methods of Testing Thermal Insulation and Associated Test Apparatus

    NASA Technical Reports Server (NTRS)

    2004-01-01

    The system and method for testing thermal insulation uses a cryostatic insulation tester having a vacuum chamber and a cold mass including a test chamber and upper and lower guard chambers adjacent thereto. The thermal insulation is positioned within the vacuum chamber and adjacent the cold mass. Cryogenic liquid is supplied to the test chamber, upper guard and lower guard to create a first gas layer in an upper portion of the lower guard chamber and a second gas layer in an upper portion of the test chamber. Temperature are sensed within the vacuum chamber to test the thermal insulation.

  16. Polyimide Aerogel Thin Films

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann; Guo, Haiquan

    2012-01-01

    Polyimide aerogels have been crosslinked through multifunctional amines. This invention builds on "Polyimide Aerogels With Three-Dimensional Cross-Linked Structure," and may be considered as a continuation of that invention, which results in a polyimide aerogel with a flexible, formable form. Gels formed from polyamic acid solutions, end-capped with anhydrides, and cross-linked with the multifunctional amines, are chemically imidized and dried using supercritical CO2 extraction to give aerogels having density around 0.1 to 0.3 g/cubic cm. The aerogels are 80 to 95% porous, and have high surface areas (200 to 600 sq m/g) and low thermal conductivity (as low as 14 mW/m-K at room temperature). Notably, the cross-linked polyimide aerogels have higher modulus than polymer-reinforced silica aerogels of similar density, and can be fabricated as both monoliths and thin films.

  17. Thermalization processes in interacting Anderson insulators

    NASA Astrophysics Data System (ADS)

    Ovadyahu, Z.

    2015-01-01

    This paper describes experiments utilizing a unique property of electron glasses to gain information on the fundamental nature of the interacting Anderson-localized phase. The methodology is based on measuring the energy absorbed by the electronic system from alternating electromagnetic fields as a function of their frequency. Experiments on three-dimensional (3D) amorphous indium-oxide films suggest that, in the strongly localized regime, the energy spectrum is discrete and inelastic electron-electron events are strongly suppressed. These results imply that, at low temperatures, electron thermalization and finite conductivity depend on coupling to the phonon bath. The situation is different for samples nearing the metal-insulator transition; in insulating samples that are close to the mobility edge, energy absorption persists to much higher frequencies. Comparing these results with previously studied 2D samples [Ovadyahu, Phys. Rev. Lett. 108, 156602 (2012), 10.1103/PhysRevLett.108.156602] demonstrates that the mean-level spacing (on a single-particle basis) is not the only relevant scale in this problem. The possibility of delocalization by many-body effects and the relevance of a nearby mobility edge (which may be a many-body edge) are discussed.

  18. Carboranylcyclotriphosphazenes and their polymers. [thermal insulation

    NASA Technical Reports Server (NTRS)

    Allcock, H. R.; Obrien, J. P.; Scopelianos, A. G.; Fewell, L. L. (Inventor)

    1981-01-01

    Carboranyl-substituted polyphosphazenes are prepared by heat polymerizing a carboranyl halocyclophosphazene at 250 C for about 120 hours in the absence of oxygen and moisture. The cyclophosphazene is obtained by allowing a lithium carborane, e.g., the reaction product of methyl-o-carborane with n-butyllithium in ethyl ether, to react with e.g., hexachlorocyclotriphosphazene at ambient temperatures and in anhydrous conditions. For greater stability in the presence of moisture, the chlorine substituents of the polymer are then replaced by aryloxy or alkoxy groups, such as CF3CH2O. The new substantially inorganic polymers are thermally stable materials which produce a high char yield when exposed to extreme temperatures, and can thus serve to insulate less heat and fire resistant substances.

  19. Flexible Polyimide Aerogel Cross-linked by Poly(maleic Anhydride-alt-alkylene)

    NASA Technical Reports Server (NTRS)

    Guo, Haiquan; Meador, Mary Ann B.; Wilkewitz, Brittany Marie

    2014-01-01

    Aerogels are potential materials for aerospace applications due to their lower thermal conductivity, lighter weight, and low dielectric constant. However, silica aerogels are restricted due to their inherent fragility, hygroscopic nature, and poor mechanical properties, especially in extreme aerospace environments. In order to fit the needs of aerospace applications, developing new thermal insulation materials that are flexible, and moisture resistant is needed. To this end, we fabricated a series of polyimide aerogels crosslinked with different poly(maleic anhydride-alt-alkylene)s as seen in Scheme 1. The polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA), and different diamines or diamine combinations. The resulting aerogels have low density (0.06 gcm3 to 0.16 gcm3) and high surface area (240-440 m2g). The effect of the different backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed. These novel polyalkylene-imide aerogels may be potential candidates for applications such as space suit insulation for planetary surface missions, insulation for inflatable structures for habitats, inflatable aerodynamic decelerators for entry, descent and landing (EDL) operations, and cryotank insulation for advance space propulsion systems. Scheme 1. Network of polyimide aerogels crosslinked with deifferent poly(maleic anhydride).

  20. Thermal Conductivity of Powder Insulations for Cryogenic Storage Vessels

    NASA Astrophysics Data System (ADS)

    Choi, Y. S.; Barrios, M. N.; Chang, H. M.; Van Sciver, S. W.

    2006-04-01

    The objective of the present work was to develop a precise instrument for measuring the thermal conductivity of powder insulating materials over a temperature range from 20 K to near room temperature. The instrument consists of two concentric copper cylinders with the annular space filled with the insulating material. The outer cylinder is thermally anchored to the coldhead of a single stage Gifford-McMahon cryocooler, while the inner copper cylinder is used for generating uniform heat flux through the insulating material. The temperature of both cylinders is measured at several locations to ensure uniform boundary conditions. The entire apparatus is wrapped in multi-layer insulation and suspended in a vacuum cryostat that provides an insulating environment. For a supplied heat flux, the temperature difference between the two cylinders is measured in steady state, from which the thermal conductivity of powder insulation is calculated and compared with published results.

  1. Carbon nanomaterials in silica aerogel matrices

    SciTech Connect

    Hamilton, Christopher E; Chavez, Manuel E; Duque, Juan G; Gupta, Gautam; Doorn, Stephen K; Dattelbaum, Andrew M; Obrey, Kimberly A D

    2010-01-01

    Silica aerogels are ultra low-density, high surface area materials that are extremely good thermal insulators and have numerous technical applications. However, their mechanical properties are not ideal, as they are brittle and prone to shattering. Conversely, single-walled carbon nanotubes (SWCNTs) and graphene-based materials, such as graphene oxide, have extremely high tensile strength and possess novel electronic properties. By introducing SWCNTs or graphene-based materials into aerogel matrices, it is possible to produce composites with the desirable properties of both constituents. We have successfully dispersed SWCNTs and graphene-based materials into silica gels. Subsequent supercritical drying results in monolithic low-density composites having improved mechanical properties. These nanocomposite aerogels have great potential for use in a wide range of applications.

  2. Thermal Insulation Testing Method and Apparatus

    NASA Technical Reports Server (NTRS)

    Fesmire, James E. (Inventor); Augustynowicz, Stanislaw D. (Inventor)

    2004-01-01

    A test apparatus and method of its use for evaluating various performance aspects of a test specimen is disclosed. A chamber within a housing contains a cold mass tank with a contact surface in contact with a first surface of a test specimen. The first surface of the test specimen is spaced from the second surface of the test specimen by a thickness. The second surface of the test specimen is maintained at a a constant temperature by a liquid disposed within the cold mass tank. A boil-off flow rate of the gas is monitored and provided to a processor along with the temperature of the first and second surfaces of the test specimen. The processor calculates thermal insulation values of the test specimen including comparative values for heat flux and apparent thermal conductivity k-value). The test specimen may be placed in any vacuum pressure level ranging from about 0.01 millitorr to 1,000,000 millitorr with different residual gases as desired. The test specimen may be placed under a mechanical load with the cold mass tank and another factors may be imposed upon the test specimen so as to simulate the actual use conditions.

  3. Thermal insulation testing method and apparatus

    NASA Technical Reports Server (NTRS)

    Fesmire, James E. (Inventor); Augustynowicz, Stanislaw D. (Inventor)

    2004-01-01

    A test apparatus and method of its use for evaluating various performance aspects of a test specimen is disclosed. A chamber within a housing contains a cold mass tank with a contact surface in contact with a first surface of a test specimen. The first surface of the test specimen is spaced from the second surface of the test specimen by a thickness. The second surface of the test specimen is maintained at a desired warm temperature. The first surface is maintained at a constant temperature by a liquid disposed within the cold mass tank. A boil-off flow rate of the gas is monitored and provided to a processor along with the temperature of the first and second surfaces of the test specimen. The processor calculates thermal insulation values of the test specimen including comparative values for heat flux and apparent thermal conductivity (k-value). The test specimen may be placed in any vacuum pressure level ranging from about 0.01 millitorr to 1,000,000 millitorr with different residual gases as desired. The test specimen may be placed under a mechanical load with the cold mass tank and another factors may be imposed upon the test specimen so as to simulate the actual use conditions.

  4. Integrated Thermal Insulation System for Spacecraft

    NASA Technical Reports Server (NTRS)

    Kolodziej, Paul (Inventor); Bull, Jeff (Inventor); Kowalski, Thomas (Inventor); Switzer, Matthew (Inventor)

    1998-01-01

    An integrated thermal protection system (TPS) for a spacecraft includes a grid that is bonded to skin of the spacecraft, e.g., to support the structural loads of the spacecraft. A plurality of thermally insulative, relatively large panels are positioned on the grid to cover the skin of the spacecraft to which the grid has been bonded. Each panel includes a rounded front edge and a front flange depending downwardly from the front edge. Also, each panel includes a rear edge formed with a rounded socket for receiving the rounded front edge of another panel therein, and a respective rear flange depends downwardly from each rear edge. Pins are formed on the front flanges, and pin receptacles are formed on the rear flanges, such that the pins of a panel mechanically interlock with the receptacles of the immediately forward panel. To reduce the transfer to the skin of heat which happens to leak through the panels to the grid, the grid includes stringers that are chair-shaped in cross-section.

  5. Polybenzoxazine aerogels: Synthesis, characterization, conversion to porous carbons, and energetic composites

    NASA Astrophysics Data System (ADS)

    Mahadik-Khanolkar, Shruti

    Aerogels are nanoporous, low-density bulk objects, consisting of three-dimensional assemblies of nanoparticle. Structured similarly, polymeric aerogels are emerging as a mechanically strong alternative to traditional silica aerogels, which are fragile. Amongst polymeric aerogels, those based on polybenzoxazine (PBO - a type of phenolic resin), are extremely robust and comprise an economic alternative to resorcinol-formaldehyde aerogels, also a class of phenolic resins, as the main source of carbon aerogels. The drawback of the PBO chemistry has been the long (days) processing time at high-temperatures (>130 °C). Herewith, we have developed an energy- and time-efficient process to PBO aerogels by inducing acid-catalyzed gelation at room-temperature completed in a few hours. The new aerogels are compared directly with their conventional counterparts and are found equivalent or better in terms of mechanical strength, thermal insulation value, surface area and carbonization yield. Hexahydrated iron chloride (FeCl3.6H2O) is a fairly strong Bronsted acid, which, based on the above, catalyzes formation interpenetrating networks of PBO and iron oxide nanoparticles (PBO-FeOx). Pyrolysis of that intimate mixture of a carbon source (PBO) and iron oxide undergoes smelting to highly porous (>90% v/v) monolithic metallic iron aerogels. The porous network was loaded with oxidizers (e.g., LiClO4) into a new class of energetic materials (thermites, explosives, pyrotechnics). The PBO aerogels developed here comprise a wide-base platform for use as thermal insulators in civil and transportation applications (PBO aerogels themselves), electrodes for fuel cells, lithium ion batteries (nanoporous carbons), catalysts and energetic materials (PBO-FeOx).

  6. Cellulose-silica aerogels.

    PubMed

    Demilecamps, Arnaud; Beauger, Christian; Hildenbrand, Claudia; Rigacci, Arnaud; Budtova, Tatiana

    2015-05-20

    Aerogels based on interpenetrated cellulose-silica networks were prepared and characterised. Wet coagulated cellulose was impregnated with silica phase, polyethoxydisiloxane, using two methods: (i) molecular diffusion and (ii) forced flow induced by pressure difference. The latter allowed an enormous decrease in the impregnation times, by almost three orders of magnitude, for a sample with the same geometry. In both cases, nanostructured silica gel was in situ formed inside cellulose matrix. Nitrogen adsorption analysis revealed an almost threefold increase in pores specific surface area, from cellulose aerogel alone to organic-inorganic composite. Morphology, thermal conductivity and mechanical properties under uniaxial compression were investigated. Thermal conductivity of composite aerogels was lower than that of cellulose aerogel due to the formation of superinsulating mesoporous silica inside cellulose pores. Furthermore, composite aerogels were stiffer than each of reference aerogels. PMID:25817671

  7. Heat transfer in thermal insulations - recent progress in analysis

    SciTech Connect

    Fricke, J.; Caps, R.

    1988-09-01

    Thermal insulations made of fibers, powders, or porous gels are characterized best with respect to their infrared optical thickness. (i) In optically thick insulations, where diffusion of infrared radiation occurs, the contributions from solid conduction and radiative transport are superimposed additively. (ii) For optically thin insulations a complex coupling mechanism causes the total heat transfer to be larger than the sum of the components; this holds especially for low emissivity boundaries. In this paper recent progress in the investigation of evacuated thermal insulations is reviewed.

  8. Application of effective thermal insulating materials in firing furnaces

    SciTech Connect

    Kryzhanovskii, K.S.; Chernyl, V.I.; Dunaevskii, O.M.; Korzh, A.I.; Sedoi, N.I.

    1986-07-01

    It was established that the application of thermal insulation in high-heat thermal units makes it possible to save up to 2 tons of standard fuel per year. A survey of the furnace installations of the porcelain and faience field and the thermal balance calculations showed that the walls and the roof of the firing zone of the furnances form the main sources of heat losses. Basalt sheets were introduced for thermal insulation of the roof. The use of BTK-1 basalt sheet as a supplementary thermal insulation makes it possible to reduce heat loss through the furnace roof by 13% as compared to the conventional method of thermal insulation of the tunnel furnace using diatomite chips.

  9. Mechanically Strong, Lightweight Porous Materials Developed (X-Aerogels)

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas

    2005-01-01

    Aerogels are attractive materials for a variety of NASA missions because they are ultralightweight, have low thermal conductivity and low-dielectric constants, and can be readily doped with other materials. Potential NASA applications for these materials include lightweight insulation for spacecraft, habitats, and extravehicular activity (EVA) suits; catalyst supports for fuel cell and in situ resource utilization; and sensors for air- and water-quality monitoring for vehicles, habitats, and EVA suits. Conventional aerogels are extremely fragile and require processing via supercritical fluid extraction, which adds cost to the production of an aerogel and limits the sizes and geometries of samples that can be produced from these materials. These issues have severely hampered the application of aerogels in NASA missions.

  10. In Vivo Ultrasonic Detection of Polyurea Crosslinked Silica Aerogel Implants

    PubMed Central

    Sabri, Firouzeh; Sebelik, Merry E.; Meacham, Ryan; Boughter, John D.; Challis, Mitchell J.; Leventis, Nicholas

    2013-01-01

    Background Polyurea crosslinked silica aerogels are highly porous, lightweight, and mechanically strong materials with great potential for in vivo applications. Recent in vivo and in vitro studies have demonstrated the biocompatibility of this type of aerogel. The highly porous nature of aerogels allows for exceptional thermal, electric, and acoustic insulating capabilities that can be taken advantage of for non-invasive external imaging techniques. Sound-based detection of implants is a low cost, non-invasive, portable, and rapid technique that is routinely used and readily available in major clinics and hospitals. Methodology In this study the first in vivo ultrasound response of polyurea crosslinked silica aerogel implants was investigated by means of a GE Medical Systems LogiQe diagnostic ultrasound machine with a linear array probe. Aerogel samples were inserted subcutaneously and sub-muscularly in a) fresh animal model and b) cadaveric human model for analysis. For comparison, samples of polydimethylsiloxane (PDMS) were also imaged under similar conditions as the aerogel samples. Conclusion/significance Polyurea crosslinked silica aerogel (X-Si aerogel) implants were easily identified when inserted in either of the regions in both fresh animal model and cadaveric model. The implant dimensions inferred from the images matched the actual size of the implants and no apparent damage was sustained by the X-Si aerogel implants as a result of the ultrasonic imaging process. The aerogel implants demonstrated hyperechoic behavior and significant posterior shadowing. Results obtained were compared with images acquired from the PDMS implants inserted at the same location. PMID:23799093

  11. Composite multilayer insulations for thermal protection of aerospace vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Pitts, William C.

    1989-01-01

    Composite flexible multilayer insulation systems (MLI), consisting of alternating layers of metal foil and scrim cloth or insulation quilted together using ceramic thread, were evaluated for thermal performance and compared with a silica fibrous (baseline) insulation system. The systems studied included: (1) alternating layers of aluminoborosilicate (ABS) scrim cloth and stainless steel foil, with silica, ABS, or alumina insulation; (2) alternating layers of scrim cloth and aluminum foil, with silica or ABS insulation; (3) alternating layers of aluminum foil and silica or ABS insulation; and (4) alternating layers of aluminum-coated polyimide placed on the bottom of the silica insulation. The MLIs containing aluminum were the most efficient, measuring as little as half the backface temperature increase of the baseline system.

  12. Electrostatic Separation Of Layers In Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep

    1995-01-01

    Layers in multilayer insulation charged to keep them separated by electrostatic repulsion, eliminating need for spacer nets. Removal of spacer nets reduces conduction of heat between layers. Insulation in question type used to slow leakage of heat into Dewar flasks containing liquid helium. Proposal originally applied to insulation in cryogenic cooling subsystems of infrared-detector systems in outer space, also appears applicable to small panels of insulation for terrestrial cryogenic equipment, provided layers contained in evacuated spaces and weight of each layer small fraction of electrostatic force upon it.

  13. Standard specification for glass fiber felt thermal insulation. ASTM standard

    SciTech Connect

    Not Available

    1997-01-01

    This specification is under the jurisdiction of ASTM Committee C-16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.23 on Blanket and Loose Fill Insulation. Current edition approved Dec. 10, 1996. Published January 1997. Originally published as C 1086-87. Last previous edition was C 1086-90a.

  14. Thermal insulator design for optimizing the efficiency of thermal flying height control sliders

    NASA Astrophysics Data System (ADS)

    Li, Hui; Yin, Chia-Ti; Talke, Frank E.

    2009-04-01

    This paper is concerned with the optimization of the location and size of thermal flying height control (TFC) elements in magnetic recording sliders. It investigated the performance of a so-called thermal insulator positioned adjacent to the heater to control the temperature distribution inside the slider. A parametric study of the thermal conductivity, thickness, and location of the thermal insulator was performed to improve the thermal actuation and thermal efficiency. Optimization of the dimensions and properties of a thermal insulator was found to achieve a substantial reduction in the flying height of the read/write elements. In addition, the magnitude of the thermal actuation was found to increase.

  15. Aerogel-supported filament

    DOEpatents

    Wuest, Craig R.; Tillotson, Thomas M.; Johnson, III, Coleman V.

    1995-01-01

    The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces.

  16. Aerogel-supported filament

    DOEpatents

    Wuest, C.R.; Tillotson, T.M.; Johnson, C.V. III

    1995-05-16

    The present invention is a thin filament embedded in a low density aerogel for use in radiation detection instruments and incandescent lamps. The aerogel provides a supportive matrix that is thermally and electrically nonconductive, mechanically strong, highly porous, gas-permeable, and transparent to ionizing radiation over short distances. A low density, open-cell aerogel is cast around a fine filament or wire, which allows the wire to be positioned with little or no tension and keeps the wire in place in the event of breakage. The aerogel support reduces the stresses on the wire caused by vibrational, gravitational, electrical, and mechanical forces. 6 Figs.

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

    NASA Astrophysics Data System (ADS)

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

    2016-09-01

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

  18. Thermal insulation blanket material. Final Report

    SciTech Connect

    Pusch, R.H.

    1982-06-01

    A study was conducted to provide a tailorable advanced blanket insulation based on a woven design having an integrally woven core structure. A highly pure quartz yarn was selected for weaving and the cells formed were filled with a microquartz felt insulation.

  19. Development of a thermal acoustical aircraft insulation material

    NASA Technical Reports Server (NTRS)

    Lin, R. Y.; Struzik, E. A.

    1974-01-01

    A process was developed for fabricating a light weight foam suitable for thermal and acoustical insulation in aircraft. The procedures and apparatus are discussed, and the foam specimens are characterized by numerous tests and measurements.

  20. Highly transparent, flexible, and thermally stable superhydrophobic ORMOSIL aerogel thin films.

    PubMed

    Budunoglu, Hulya; Yildirim, Adem; Guler, Mustafa O; Bayindir, Mehmet

    2011-02-01

    We report preparation of highly transparent, flexible, and thermally stable superhydrophobic organically modified silica (ORMOSIL) aerogel thin films from colloidal dispersions at ambient conditions. The prepared dispersions are suitable for large area processing with ease of coating and being directly applicable without requiring any pre- or post-treatment on a variety of surfaces including glass, wood, and plastics. ORMOSIL films exhibit and retain superhydrophobic behavior up to 500 °C and even on bent flexible substrates. The surface of the films can be converted from superhydrophobic (contact angle of 179.9°) to superhydrophilic (contact angle of <5°) by calcination at high temperatures. The wettability of the coatings can be changed by tuning the calcination temperature and duration. The prepared films also exhibit low refractive index and high porosity making them suitable as multifunctional coatings for many application fields including solar cells, flexible electronics, and lab on papers. PMID:21226471

  1. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    PubMed Central

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m−2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

  2. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes.

    PubMed

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D; Baughman, Ray H; Lee, Hong H; Kang, Tae June; Kim, Yong Hyup

    2016-01-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m(-2) is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated. PMID:26837457

  3. High-efficiency electrochemical thermal energy harvester using carbon nanotube aerogel sheet electrodes

    NASA Astrophysics Data System (ADS)

    Im, Hyeongwook; Kim, Taewoo; Song, Hyelynn; Choi, Jongho; Park, Jae Sung; Ovalle-Robles, Raquel; Yang, Hee Doo; Kihm, Kenneth D.; Baughman, Ray H.; Lee, Hong H.; Kang, Tae June; Kim, Yong Hyup

    2016-02-01

    Conversion of low-grade waste heat into electricity is an important energy harvesting strategy. However, abundant heat from these low-grade thermal streams cannot be harvested readily because of the absence of efficient, inexpensive devices that can convert the waste heat into electricity. Here we fabricate carbon nanotube aerogel-based thermo-electrochemical cells, which are potentially low-cost and relatively high-efficiency materials for this application. When normalized to the cell cross-sectional area, a maximum power output of 6.6 W m-2 is obtained for a 51 °C inter-electrode temperature difference, with a Carnot-relative efficiency of 3.95%. The importance of electrode purity, engineered porosity and catalytic surfaces in enhancing the thermocell performance is demonstrated.

  4. Aerogels for electronics

    SciTech Connect

    Hrubesh, L.W.

    1994-10-01

    In addition to their other exceptional properties, aerogels also exhibit unusual dielectric and electronic properties due to their nano-sized structures and high porosities. For example, aerogels have the lowest dielectric constants measured for a solid material (having values approaching 1.0); they have exceptionally high dielectric resistivities and strengths (i.e., ability to insulate very high voltages); they exhibit low dielectric loss at microwave frequencies; and some aerogels are electrically conductive and photoconductive. These properties are being exploited to provide the next generation of materials for energy storage, low power consumption, and ultra-fast electronics. We are working toward adapting these unusual materials for microelectronic applications, particularly, making thin aerogel films for dielectric substrates and for energy storage devices such as supercapacitors. Measurements are presented in this paper for the dielectric and electronic properties of aerogels, including the dielectric constant, loss factor, dielectric and electrical conductivity, volume resistivity, and dielectric strength. We also describe methods to form and characterize thin aerogel films which are being developed for numerous electronic applications. Finally, some of the electronic applications proposed for aerogels are presented. Commercialization of aerogels for electronics must await further feasibility, prototype development, and cost studies, but they are one of the key materials and are sure to have a major impact on future electronics.

  5. Outgassing of solid material into vacuum thermal insulation spaces

    NASA Technical Reports Server (NTRS)

    Wang, Pao-Lien

    1994-01-01

    Many cryogenic storage tanks use vacuum between inner and outer tank for thermal insulation. These cryogenic tanks also use a radiation shield barrier in the vacuum space to prevent radiation heat transfer. This shield is usually constructed by using multiple wraps of aluminized mylar and glass paper as inserts. For obtaining maximum thermal performance, a good vacuum level must be maintained with the insulation system. It has been found that over a period of time solid insulation materials will vaporize into the vacuum space and the vacuum will degrade. In order to determine the degradation of vacuum, the rate of outgassing of the insulation materials must be determined. Outgassing rate of several insulation materials obtained from literature search were listed in tabular form.

  6. Facilitated fabrication of high strength silica aerogels using cellulose nanofibrils as scaffold.

    PubMed

    Fu, Jingjing; Wang, Siqun; He, Chunxia; Lu, Zexiang; Huang, Jingda; Chen, Zhilin

    2016-08-20

    Monolithic cellulose nanofibrils (CNF)-silica composite aerogels were successfully prepared by immersing CNF aerogels into a silica solution in a two-step sol-gel process (initial hydrolysis of tetraethyl orthosilicate (TEOS) followed by condensation of silica particles). Aerogels were characterized by SEM, BET surface area test, bulk density and silica content analysis, FTIR spectroscopy, and compression test. The form of SiO2 existing in the composite aerogel was the spherical individual particles coated on CNF fibrils. The pH value of condensation solution was found to have great influence on the properties of the composite aerogels. By varying the pH value of condensation atmosphere from 8 to 12, the bulk densities of composite aerogels were able to be linearly increased from 0.059gcm(-3) to 0.29gcm(-3),and the silica content in the matrix sharply jumped from 3wt% to 79wt%. The porosities of the aerogels remained very high, between 85 and 96%, and the surface area of the composite aerogel reached up to 700.1m(2)g(-1). The compression properties of the composite aerogel improved greatly compared with those of the silica aerogel, about 8-30 times higher. Moreover, the compressive strength of the composite aerogel prepared in this work greatly exceeded the conventional insulation materials found in the recent commercial market, and without substantial increases in thermal conductivity. Hence, the findings of this research offer a promising application for composite aerogels and give a theoretical basis for developing new advanced materials. PMID:27178912

  7. Optimum compositions for thermal insulation of burners and regenerators

    SciTech Connect

    Zasypkin, V.I.; Popov, O.N.

    1988-07-01

    The thermal and mechanical properties of thermal insulation compositions applied by spraying were evaluated to determine the optimum composition for the parameters posed by the burners and regenerators of glass-melting furnaces. The effects of varying spray parameters on these properties were also assessed. Changes were made in the binder density while leaving the amount of filler unaltered. With an increase in binder density there was an increase in the apparent density of the insulation. Kaolin wool with an aluminoborophosphate concentrate binder was tested for thermal conductivity, apparent density, and bending, shear, and compression strength against asbestos with water glass as a binder. For walls of the regenerators and a single-layer heat insulation, insulation made from an asbestos-perlite mixture with water glass was recommended.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

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

  9. Improvements to the Synthesis of Polyimide Aerogels

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Nguyen, Baochau N.; Guo, Haiquan; Vivod, Stephanie; He, Zuhui; Malow, Ericka; Silva, Rebecca

    2011-01-01

    Cross-linked polyimide aerogels are viable approach to higher temperature, flexible insulation for inflatable decelerators. Results indicate that the all-polyimide aerogels are as strong or stronger than polymer reinforced silica aerogels at the same density. Currently, examining use of carbon nanofiber and clay nanoparticles to improve performance. Flexible, polyimide aerogels have potential utility in other applications such as space suits, habitats, shelter applications, etc. where low dusting is desired

  10. Improved Thermal-Insulation Systems for Low Temperatures

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, Stanislaw D.

    2003-01-01

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

  11. Effects of Microgravity on the Formation of Aerogels

    NASA Technical Reports Server (NTRS)

    Hunt, A. J.; Ayers, M. R.; Sibille, L.; Cronise, R. J.; Noever, D. A.

    1999-01-01

    presence of poorly controlled microporosity in aerogel leads to material non-uniformity that gives rise to increased light scattering. Investigation of the effect of gravity driven solute flows within microclusters and their effect on condensation and agglomeration reactions will enable us to improve the preparation and properties of aerogel. Increased clarity of images viewed through aerogel and decreased scattering from the pores of aerogel will significantly improve the prospects for large-scale adoption of aerogel in such applications as transparent insulating windows, high performance thermal insulation, and Cherenkov detectors.

  12. Polyimide Aerogels with Three-Dimensional Cross-Linked Structure

    NASA Technical Reports Server (NTRS)

    Panek, John

    2010-01-01

    Polyimide aerogels with three-dimensional cross-linked structure are made using linear oligomeric segments of polyimide, and linked with one of the following into a 3D structure: trifunctional aliphatic or aromatic amines, latent reactive end caps such as nadic anhydride or phenylethynylphenyl amine, and silica or silsesquioxane cage structures decorated with amine. Drying the gels supercritically maintains the solid structure of the gel, creating a polyimide aerogel with improved mechanical properties over linear polyimide aerogels. Lightweight, low-density structures are desired for acoustic and thermal insulation for aerospace structures, habitats, astronaut equipment, and aeronautic applications. Aerogels are a unique material for providing such properties because of their extremely low density and small pore sizes. However, plain silica aerogels are brittle. Reinforcing the aerogel structure with a polymer (X-Aerogel) provides vast improvements in strength while maintaining low density and pore structure. However, degradation of polymers used in cross-linking tends to limit use temperatures to below 150 C. Organic aerogels made from linear polyimide have been demonstrated, but gels shrink substantially during supercritical fluid extraction and may have lower use temperature due to lower glass transition temperatures. The purpose of this innovation is to raise the glass transition temperature of all organic polyimide aerogel by use of tri-, tetra-, or poly-functional units in the structure to create a 3D covalently bonded network. Such cross-linked polyimides typically have higher glass transition temperatures in excess of 300 400 C. In addition, the reinforcement provided by a 3D network should improve mechanical stability, and prevent shrinkage on supercritical fluid extraction. The use of tri-functional aromatic or aliphatic amine groups in the polyimide backbone will provide such a 3D structure.

  13. Silica aerogel-polymer nanocomposites and new nanoparticle syntheses

    NASA Astrophysics Data System (ADS)

    Boday, Dylan Joseph

    Aerogels are extremely high surface area, low density materials with applications including thermal and acoustic insulators, radiation detectors and cometary dust particle traps. However, their low density and aggregate structure makes them extremely fragile and practically impossible to machine or handle without breaking. This has led to the development of aerogel composites with enhanced mechanical properties through the addition of polymers or surface modifiers. To date, attempts to strengthen aerogels have come with significant increases in density and processing time. Here I will describe our search for a solution to these problems with our invention using methyl cyanoacrylate chemical vapor deposition (CVD) to strengthen silica, aminated silica and bridged polysilsesquioxane aerogels. This approach led to a strength improvement of the composites within hours and the strongest composite prepared had a 100x strength improvement over the precursor aerogel. We also developed the first approach to control the molecular weight of the polymers that reinforce silica aerogels using surface-initiated atom transfer radical polymerization (SI-ATRP). Although PMMA reinforcement of silica aerogels improved the mechanical properties, further strength improvements were achieved by cross-linking the grafted PMMA. Additionally, we developed the first silica aerogels reinforced with polyaniline nanofibers that were strong and electrically conductive. Reinforcing silica aerogels with polyaniline allowed them to be used as a sensor for the detection of protonating and deprotonating gaseous species. Finally we developed a new approach for the synthesis of silica and bridged polysilsesquioxane spheres using a surfactant free synthesis. This approach allowed for the first in-situ incorporation of base sensitive functionalities during the sol-gel polymerization.

  14. Thermal management of thermoacoustic sound projectors using a free-standing carbon nanotube aerogel sheet as a heat source

    NASA Astrophysics Data System (ADS)

    Aliev, Ali E.; Mayo, Nathanael K.; Baughman, Ray H.; Avirovik, Dragan; Priya, Shashank; Zarnetske, Michael R.; Blottman, John B.

    2014-10-01

    Carbon nanotube (CNT) aerogel sheets produce smooth-spectra sound over a wide frequency range (1-105 Hz) by means of thermoacoustic (TA) sound generation. Protective encapsulation of CNT sheets in inert gases between rigid vibrating plates provides resonant features for the TA sound projector and attractive performance at needed low frequencies. Energy conversion efficiencies in air of 2% and 10% underwater, which can be enhanced by further increasing the modulation temperature. Using a developed method for accurate temperature measurements for the thin aerogel CNT sheets, heat dissipation processes, failure mechanisms, and associated power densities are investigated for encapsulated multilayered CNT TA heaters and related to the thermal diffusivity distance when sheet layers are separated. Resulting thermal management methods for high applied power are discussed and deployed to construct efficient and tunable underwater sound projector for operation at relatively low frequencies, 10 Hz-10 kHz. The optimal design of these TA projectors for high-power SONAR arrays is discussed.

  15. Studying the Properties of Aerogel at MSFC

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Scientists at Marshall Space Flight Center (MSFC) have been studying the properties of Aerogel for several years. Aerogel, the lightest solid known to man, has displayed a high quality for insulation. Because of its smoky countenance, it has yet to be used as an insulation on windows, but has been used in the space program on the rover Sojourner, and has been used as insulation in the walls of houses and in automobile engine compartments. As heat is applied to Aerogel, scientist Dr. David Noever of Space Sciences Laboratory, Principal Investigator of Aerogel, studies for its properties trying to uncover the secret to making Aerogel a clear substance. Once found, Aerogel will be a major component in the future of glass insulation.

  16. Aerogel: From Aerospace to Apparel

    NASA Technical Reports Server (NTRS)

    2001-01-01

    Aspen Systems Inc. developed an aerogel-manufacturing process solved the handling problems associated with aerogel-based insulation products. Their aerogels can now be manufactured into blankets, thin sheets, beads, and molded parts; and may be transparent, translucent, or opaque. Aspen made the material effective for window and skylight insulation, non-flammable building insulation, and inexpensive firewall insulation that will withstand fires in homes and buildings, and also assist in the prevention of forest fires. Another Aspen product is Spaceloft(TM); an inexpensive, flexible blanket that incorporates a thin layer of aerogel embedded directly into the fabric. Spaceloft, is incorporated into jackets intended for wear in extremely harsh conditions and activities, such as Antarctic expeditions.

  17. Thin Thermal-Insulation Blankets for Very High Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2003-01-01

    Thermal-insulation blankets of a proposed type would be exceptionally thin and would endure temperatures up to 2,100 C. These blankets were originally intended to protect components of the NASA Solar Probe spacecraft against radiant heating at its planned closest approach to the Sun (a distance of 4 solar radii). These blankets could also be used on Earth to provide thermal protection in special applications (especially in vacuum chambers) for which conventional thermal-insulation blankets would be too thick or would not perform adequately.

  18. Newly developed foam ceramic body shows promise as thermal insulation material at 3000 deg F

    NASA Technical Reports Server (NTRS)

    Blocker, E. W.; Paul, R. D.

    1967-01-01

    Optimized zirconia foam ceramic body shows promise for use as a thermal insulation material. The insulating media displays low density and thermal conductivity, good thermal shock resistance, high melting point, and mechanical strength.

  19. Structural heat pipe. [for spacecraft wall thermal insulation system

    NASA Technical Reports Server (NTRS)

    Ollendorf, S. (Inventor)

    1974-01-01

    A combined structural reinforcing element and heat transfer member is disclosed for placement between a structural wall and an outer insulation blanket. The element comprises a heat pipe, one side of which supports the outer insulation blanket, the opposite side of which is connected to the structural wall. Heat penetrating through the outer insulation blanket directly reaches the heat pipe and is drawn off, thereby reducing thermal gradients in the structural wall. The element, due to its attachment to the structural wall, further functions as a reinforcing member.

  20. Few layer graphene based superlattices as efficient thermal insulators

    NASA Astrophysics Data System (ADS)

    Ni, Yuxiang; Chalopin, Yann; Volz, Sebastian

    2013-09-01

    While graphene and few layer graphene (FLG) are considered as having the highest thermal conductivity in their in-plane directions, our molecular dynamics (MD) simulations however show that those systems are also characterized by a superior thermal contact resistance, which could be largely tuned with the layer number when in contact with a silica substrate. Taking advantages of such a resistive interface, MD simulations show that SiO2/FLG superlattices have a thermal conductivity as low as 0.30 W/m K, exhibiting a promising prospect in nano-scale thermal insulation. These findings pave the way for an improved thermal management of nanoscale systems such as thermal barrier coatings and phase change memory materials with atomic-scale super-insulators.

  1. Polyimide aerogels cross-linked through amine functionalized polyoligomeric silsesquioxane.

    PubMed

    Guo, Haiquan; Meador, Mary Ann B; McCorkle, Linda; Quade, Derek J; Guo, Jiao; Hamilton, Bart; Cakmak, Miko; Sprowl, Guilherme

    2011-02-01

    We report the first synthesis of polyimide aerogels cross-linked through a polyhedral oligomeric silsesquioxane, octa(aminophenyl)silsesquioxane (OAPS). Gels formed from polyamic acid solutions of 3,3',4,4'-biphenyltetracarboxylic dianhydride (BPDA), bisaniline-p-xylidene (BAX) and OAPS were chemically imidized and dried using supercritical CO(2) extraction to give aerogels having density around 0.1 g/cm(3). The aerogels are greater than 90 % porous, have high surface areas (230 to 280 m(2)/g) and low thermal conductivity (14 mW/m-K at room temperature). Notably, the polyimide aerogels cross-linked with OAPS have higher modulus than polymer reinforced silica aerogels of similar density and can be fabricated as both monoliths and thin films. Thin films of the aerogel are flexible and foldable making them an ideal insulation for space suits, and inflatable structures for habitats or decelerators for planetary re-entry, as well as more down to earth applications. PMID:21294517

  2. Comparative study of aerogels obtained from differently prepared nanocellulose fibers.

    PubMed

    Chen, Wenshuai; Li, Qing; Wang, Youcheng; Yi, Xin; Zeng, Jie; Yu, Haipeng; Liu, Yixing; Li, Jian

    2014-01-01

    This article describes the fabrication of nanocellulose fibers (NCFs) with different morphologies and surface properties from biomass resources as well as their self-aggregation into lightweight aerogels. By carefully modulating the nanofibrillation process, four types of NCFs could be readily fabricated, including long aggregated nanofiber bundles, long individualized nanofibers with surface C6 -carboxylate groups, short aggregated nanofibers, and short individualized nanofibers with surface sulfate groups. Free-standing lightweight aerogels were obtained from the corresponding aqueous NCF suspensions through freeze-drying. The structure of the aerogels could be controlled by manipulating the type of NCFs and the concentration of their suspensions. A possible mechanism for the self-aggregation of NCFs into two- or three-dimensional aerogel nanostructures was further proposed. Owing to web-like structure, high porosity, and high surface reactivity, the NCF aerogels exhibited high mechanical flexibility and ductility, and excellent properties for water uptake, removal of dye pollutants, and the use as thermal insulation materials. The aerogels also displayed sound-adsorption capability at high frequencies. PMID:24420495

  3. Silylation of low-density silica and bridged polysilsesquioxane aerogels

    SciTech Connect

    DeFriend, K. A.; Loy, D. A.; Salazar, K. V.; Wilson, K. V.

    2004-01-01

    Silica and bridged polysilsesquioxane aerogels are low-density materials that are attractive for applications such as thermal insulation, porous separation media or catalyst supports, adsorbents, and cometary dust capture agents. However, aerogels are notoriously weak and brittle making it difficult to handle and machine monoliths into desired forms. This complication prevents the development of many applications that would otherwise benefit from the use of the low-density materials. Here, we will describe our efforts to chemically modify and mechanically enhance silica-based aerogels using chemical vapor techniques without sacrificing their characteristic low densities. Monolithic silica and organic-bridged polysilsesquioxane aerogels were prepared by sol-gel polymerization of the respective methoxysilane monomers followed by supercritical carbon dioxide drying of the gels. Then the gels were reactively modified with silylating agents to demonstrate the viability of CVD modification of aerogels, and to determine the effects of silylation of surface silanols on the morphology, surface area, and mechanical properties of the resulting aerogels.

  4. High temperature insulation materials for reradiative thermal protection systems

    NASA Technical Reports Server (NTRS)

    Hughes, T. A.

    1972-01-01

    Results are presented of a two year program to evaluate packaged thermal insulations for use under a metallic radiative TPS of a shuttle orbiter vehicle. Evaluations demonstrated their survival for up to 100 mission reuse cycles under shuttle acoustic and thermal loads with peak temperatures of 1000 F, 1800 F, 2000 F, 2200 F and 2500 F. The specimens were composed of low density refractory fiber felts, packaged in thin gage metal foils. In addition, studies were conducted on the venting requirements of the packages, salt spray resistance of the metal foils, and the thermal conductivity of many of the insulations as a function of temperature and ambient air pressure. Data is also presented on the radiant energy transport through insulations, and back-scattering coefficients were experimentally determined as a function of source temperature.

  5. Prediction of the Effective Thermal Conductivity of Powder Insulation

    NASA Astrophysics Data System (ADS)

    Jin, Lingxue; Park, Jiho; Lee, Cheonkyu; Jeong, Sangkwon

    The powder insulation method is widely used in structural and cryogenic systems such as transportation and storage tanks of cryogenic fluids. The powder insulation layer is constructed by small particle powder with light weight and some residual gas with high porosity. So far, many experiments have been carried out to test the thermal performance of various kinds of powder, including expanded perlite, glass microspheres, expanded polystyrene (EPS). However, it is still difficult to predict the thermal performance of powder insulation by calculation due to the complicated geometries, including various particle shapes, wide powder diameter distribution, and various pore sizes. In this paper, the effective thermal conductivity of powder insulation has been predicted based on an effective thermal conductivity calculationmodel of porous packed beds. The calculation methodology was applied to the insulation system with expanded perlite, glass microspheres and EPS beads at cryogenic temperature and various vacuum pressures. The calculation results were compared with previous experimental data. Moreover, additional tests were carried out at cryogenic temperature in this research. The fitting equations of the deformation factor of the area-contact model are presented for various powders. The calculation results show agood agreement with the experimental results.

  6. Measurement of clothing thermal insulation and moisture vapour resistance using a novel perspiring fabric thermal manikin

    NASA Astrophysics Data System (ADS)

    Fan, J.; Chen, Y. S.

    2002-07-01

    Thermal manikins are necessary instruments for measuring the thermal insulation and moisture vapour resistance of clothing systems, which are important parameters relevant to clothing thermal comfort. Although many thermal manikins have been developed since the first example in the 1940s, simulation of human perspiration in thermal manikins remains a challenge. This paper reports on a novel perspiring fabric thermal manikin, which simulates gaseous perspiration by moisture transfer through a `skin' made of a breathable fabric. The manikin has been used to measure the thermal insulation and moisture vapour resistances of clothing ensembles, and demonstrated high accuracy and reproducibility.

  7. Thermally driven spin torques in layered magnetic insulators

    NASA Astrophysics Data System (ADS)

    Bender, Scott A.; Tserkovnyak, Yaroslav

    2016-02-01

    Thermally driven spin-transfer torques have recently been reported in electrically insulating ferromagnet |normal -metal heterostructures. In this paper, we propose two physically distinct mechanisms for such torques. The first is a local effect: out-of-equilibrium, thermally activated magnons in the ferromagnet, driven by a spin Seebeck effect, exert a torque on the magnetization via magnon-magnon scattering with coherent dynamics. The second is a nonlocal effect which requires an additional magnetic layer to provide the symmetry breaking necessary to realize a thermal torque. The simplest structure in which to induce a nonlocal thermal torque is a spin valve composed of two insulating magnets separated by a normal metal spacer; there, a thermal flux generates a pure spin current through the spin valve, which results in a torque when the magnetizations of the layers are misaligned.

  8. Thermal Infrared Inspection of Roof Insulation Using Unmanned Aerial Vehicles

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Jung, J.; Sohn, G.; Cohen, M.

    2015-08-01

    UAVs equipped with high-resolution thermal cameras provide an excellent investigative tool used for a multitude of building-specific applications, including roof insulation inspection. We have presented in this study a relative thermographic calibration algorithm and a superpixel Markov Random Field model to address problems in thermal infrared inspection of roof insulation using UAVs. The relative thermographic radiometric calibration algorithm is designed to address the autogain problem of the thermal camera. Results show the algorithm can enhance the contrast between warm and cool areas on the roof surface in thermal images, and produces more constant thermal signatures of different roof insulations or surfaces, which could facilitate both visual interpretation and computer-based thermal anomaly detection. An automatic thermal anomaly detection algorithm based on superpixel Markov Random Field is proposed, which is more computationally efficient than pixel based MRF, and can potentially improve the production throughput capacity and increase the detection accuracy for thermal anomaly detection. Experimental results show the effectiveness of the proposed method.

  9. Estimating Clothing Thermal Insulation Using an Infrared Camera

    PubMed Central

    Lee, Jeong-Hoon; Kim, Young-Keun; Kim, Kyung-Soo; Kim, Soohyun

    2016-01-01

    In this paper, a novel algorithm for estimating clothing insulation is proposed to assess thermal comfort, based on the non-contact and real-time measurements of the face and clothing temperatures by an infrared camera. The proposed method can accurately measure the clothing insulation of various garments under different clothing fit and sitting postures. The proposed estimation method is investigated to be effective to measure its clothing insulation significantly in different seasonal clothing conditions using a paired t-test in 99% confidence interval. Temperatures simulated with the proposed estimated insulation value show closer to the values of actual temperature than those with individual clothing insulation values. Upper clothing’s temperature is more accurate within 3% error and lower clothing’s temperature is more accurate by 3.7%~6.2% error in indoor working scenarios. The proposed algorithm can reflect the effect of air layer which makes insulation different in the calculation to estimate clothing insulation using the temperature of the face and clothing. In future, the proposed method is expected to be applied to evaluate the customized passenger comfort effectively. PMID:27005625

  10. Estimating Clothing Thermal Insulation Using an Infrared Camera.

    PubMed

    Lee, Jeong-Hoon; Kim, Young-Keun; Kim, Kyung-Soo; Kim, Soohyun

    2016-01-01

    In this paper, a novel algorithm for estimating clothing insulation is proposed to assess thermal comfort, based on the non-contact and real-time measurements of the face and clothing temperatures by an infrared camera. The proposed method can accurately measure the clothing insulation of various garments under different clothing fit and sitting postures. The proposed estimation method is investigated to be effective to measure its clothing insulation significantly in different seasonal clothing conditions using a paired t-test in 99% confidence interval. Temperatures simulated with the proposed estimated insulation value show closer to the values of actual temperature than those with individual clothing insulation values. Upper clothing's temperature is more accurate within 3% error and lower clothing's temperature is more accurate by 3.7%~6.2% error in indoor working scenarios. The proposed algorithm can reflect the effect of air layer which makes insulation different in the calculation to estimate clothing insulation using the temperature of the face and clothing. In future, the proposed method is expected to be applied to evaluate the customized passenger comfort effectively. PMID:27005625

  11. Status of reusable surface insulation thermal protection system technology programs

    NASA Technical Reports Server (NTRS)

    Greenshields, D. H.; Meyer, A. J.; Tillian, D. J.

    1972-01-01

    The development of three low-density rigidized insulation materials for the shuttle TPS application is reported. These materials consist of one high purity silica system and two systems based on mullite, an aluminum silicate. Both systems consist of fibers joined together with appropriate binders to obtain a rigidized insulation composite. Both material systems require the application of a glassy coating to provide a wear resistant, high emittance surface and to prevent the absorption of water by the fiber matrix. The technology program has addressed the development of water impervious coatings, methods of assembling the materials in design concepts while minimizing the thermal stress in the insulation, achieving compatibility between the RSI material and the structural system, and test evaluations to demonstrate the feasibility of the surface insulation concept.

  12. Waterproof Silicone Coatings of Thermal Insulation and Vaporization Method

    NASA Technical Reports Server (NTRS)

    Cagliostro, Domenick E. (Inventor)

    1999-01-01

    Thermal insulation composed of porous ceramic material can be waterproofed by producing a thin silicone film on the surface of the insulation by exposing it to volatile silicone precursors at ambient conditions. When the silicone precursor reactants are multi-functional siloxanes or silanes containing alkenes or alkynes carbon groups higher molecular weight films can be produced. Catalyst are usually required for the silicone precursors to react at room temperature to form the films. The catalyst are particularly useful in the single component system e.g. dimethylethoxysilane (DNMS) to accelerate the reaction and decrease the time to waterproof and protect the insulation. In comparison to other methods, the chemical vapor technique assures better control over the quantity and location of the film being deposited on the ceramic insulation to improve the waterproof coating.

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

    SciTech Connect

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

    1992-04-01

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

  14. Refractory insulation of hot end in stirling type thermal machines

    SciTech Connect

    Otters, J.L.

    1988-02-02

    A thermal machine is described comprising: a machine body comprised of axial body sections, the body having two opposite ends; means compressing the body between the opposite ends for holding the body sections in axially assembled relationship; a cylindrical displacer chamber in the body having a hot end and a cold end and containing a working fluid, a displacer reciprocable within the displacer chamber for displacing the fluid between the hot and cold ends thereby to subject the fluid to a thermodynamic cycle in cooperation with a compressor piston; refractory insulation means at least partly defining the displacer chamber and held in axial compression between a upper body sections associated with a thermal end of the machine body and lower body sections associated with a work end of the machine body, and means radially compressing the refractory insulation for pre-loading the refractory insulation means against tensile force exerted thereon by the working fluid.

  15. Pipeline system insulation: Thermal insulation and corrosion prevention. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    Not Available

    1994-05-01

    The bibliography contains citations concerning thermal and corrosion insulation of pipeline systems used to transport liquids and gases. Topics include thermal aging of polyurethane used for foam heating pipes, extrusion film pipeline insulation materials and processes, flexible expanded nitrile rubber pipeline insulation with Class 1 fire rating, and underground fiberglass reinforced polyester insulated pipeline systems. Applications in solar heating systems; underground water, oil, and gas pipelines; interior hot and cold water lines under seawater; and chemical plant pipeline system insulation are included. (Contains 250 citations and includes a subject term index and title list.)

  16. Pipeline system insulation: Thermal insulation and corrosion prevention. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-11-01

    The bibliography contains citations concerning thermal and corrosion insulation of pipeline systems used to transport liquids and gases. Topics include thermal aging of polyurethane used for foam heating pipes, extrusion film pipeline insulation materials and processes, flexible expanded nitrile rubber pipeline insulation with Class 1 fire rating, and underground fiberglass reinforced polyester insulated pipeline systems. Applications in solar heating systems; underground water, oil, and gas pipelines; interior hot and cold water lines under seawater; and chemical plant pipeline system insulation are included. (Contains 50-250 citations and includes a subject term index and title list.) (Copyright NERAC, Inc. 1995)

  17. Pipeline system insulation: Thermal insulation and corrosion prevention. (Latest citations from the Rubber and Plastics Research Association database). Published Search

    SciTech Connect

    1995-01-01

    The bibliography contains citations concerning thermal and corrosion insulation of pipeline systems used to transport liquids and gases. Topics include thermal aging of polyurethane used for foam heating pipes, extrusion film pipeline insulation materials and processes, flexible expanded nitrile rubber pipeline insulation with Class 1 fire rating, and underground fiberglass reinforced polyester insulated pipeline systems. Applications in solar heating systems; underground water, oil, and gas pipelines; interior hot and cold water lines under seawater; and chemical plant pipeline system insulation are included. (Contains 250 citations and includes a subject term index and title list.)

  18. Closed-pore Insulation Thermal Protection System Design Concept Development

    NASA Technical Reports Server (NTRS)

    Varisco, A.; Harris, H. G.

    1973-01-01

    The development of a unique closed-pore ceramic foam insulation (CPI) produced from low cost fly ash cenospheres is reported for space shuttle external thermal protection. Two basic design approaches were developed: bonded and mechanically fastened. A description of the concepts is presented in addition to fabrication and test results.

  19. High temperature polyimide foams for shuttle upper surface thermal insulation

    NASA Technical Reports Server (NTRS)

    Ball, G. L., III; Leffingwell, J. W.; Salyer, I. O.; Werkmeister, D. W.

    1974-01-01

    Polyimide foams developed by Monsanto Company were examined for use as upper surface space shuttle thermal insulation. It was found that postcured polyimide foams having a density of 64 kg/cu m (4 lb/cu ft) had acceptable physical properties up to and exceeding 700 K (800 F). Physical tests included cyclic heating and cooling in vacuum, weight and dimensional stability, mechanical strength and impact resistance, acoustic loading and thermal conductivity. Molding and newly developed postcuring procedures were defined.

  20. High surface area silicon carbide-coated carbon aerogel

    DOEpatents

    Worsley, Marcus A; Kuntz, Joshua D; Baumann, Theodore F; Satcher, Jr, Joe H

    2014-01-14

    A metal oxide-carbon composite includes a carbon aerogel with an oxide overcoat. The metal oxide-carbon composite is made by providing a carbon aerogel, immersing the carbon aerogel in a metal oxide sol under a vacuum, raising the carbon aerogel with the metal oxide sol to atmospheric pressure, curing the carbon aerogel with the metal oxide sol at room temperature, and drying the carbon aerogel with the metal oxide sol to produce the metal oxide-carbon composite. The step of providing a carbon aerogel can provide an activated carbon aerogel or provide a carbon aerogel with carbon nanotubes that make the carbon aerogel mechanically robust. Carbon aerogels can be coated with sol-gel silica and the silica can be converted to silicone carbide, improved the thermal stability of the carbon aerogel.

  1. Thermal insulation attaching means. [adhesive bonding of felt vibration insulators under ceramic tiles

    NASA Technical Reports Server (NTRS)

    Leger, L. J. (Inventor)

    1978-01-01

    An improved isolation system is provided for attaching ceramic tiles of insulating material to the surface of a structure to be protected against extreme temperatures of the nature expected to be encountered by the space shuttle orbiter. This system isolates the fragile ceramic tiles from thermally and mechanically induced vehicle structural strains. The insulating tiles are affixed to a felt isolation pad formed of closely arranged and randomly oriented fibers by means of a flexible adhesive and in turn the felt pad is affixed to the metallic vehicle structure by an additional layer of flexible adhesive.

  2. Organic aerogel microspheres and fabrication method therefor

    DOEpatents

    Mayer, S.T.; Kong, F.M.; Pekala, R.W.; Kaschmitter, J.L.

    1996-04-16

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  3. Organic aerogel microspheres and fabrication method therefor

    DOEpatents

    Mayer, Steven T.; Kong, Fung-Ming; Pekala, Richard W.; Kaschmitter, James L.

    1996-01-01

    Organic aerogel microspheres which can be used in capacitors, batteries, thermal insulation, adsorption/filtration media, and chromatographic packings, having diameters ranging from about 1 micron to about 3 mm. The microspheres can be pyrolyzed to form carbon aerogel microspheres. This method involves stirring the aqueous organic phase in mineral oil at elevated temperature until the dispersed organic phase polymerizes and forms nonsticky gel spheres. The size of the microspheres depends on the collision rate of the liquid droplets and the reaction rate of the monomers from which the aqueous solution is formed. The collision rate is governed by the volume ratio of the aqueous solution to the mineral oil and the shear rate, while the reaction rate is governed by the chemical formulation and the curing temperature.

  4. Electrically insulating thermal nano-oils using 2D fillers.

    PubMed

    Taha-Tijerina, Jaime; Narayanan, Tharangattu N; Gao, Guanhui; Rohde, Matthew; Tsentalovich, Dmitri A; Pasquali, Matteo; Ajayan, Pulickel M

    2012-02-28

    Different nanoscale fillers have been used to create composite fluids for applications such as thermal management. The ever increasing thermal loads in applications now require advanced operational fluids, for example, high thermal conductivity dielectric oils in transformers. These oils require excellent filler dispersion, high thermal conduction, but also electrical insulation. Such thermal oils that conform to this thermal/electrical requirement, and yet remain in highly suspended stable state, have not yet been synthesized. We report here the synthesis and characterization of stable high thermal conductivity Newtonian nanofluids using exfoliated layers of hexagonal boron nitride in oil without compromising its electrically insulating property. Two-dimensional nanosheets of hexagonal boron nitride are liquid exfoliated in isopropyl alcohol and redispersed in mineral oil, used as standard transformer oil, forming stable nanosuspensions with high shelf life. A high electrical resistivity, even higher than that of the base oil, is maintained for the nano-oil containing small weight fraction of the filler (0.01 wt %), whereas the thermal conductivity was enhanced. The low dissipation factor and high pour point for this nano-oil suggests several applications in thermal management. PMID:22268368

  5. Thermal Performance of Composite Flexible Blanket Insulations for Hypersonic Aerospace Vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.

    1993-01-01

    This paper describes the thermal performance of a Composite Flexible Blanket Insulation (C.F.B.I.) considered for potential use as a thermal protection system or thermal insulation for future hypersonic vehicles such as the National Aerospace Plane (N.A.S.P.). Thermophysical properties for these insulations were also measured including the thermal conductivity at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is also described. Materials tested included two surface variations of the insulations, and similar insulations coated with a Protective Ceramic Coating (P.C.C.). Surface and backface temperatures were measured in the flexible insulations and on Fibrous Refractory Composite Insulation (F.R.C.I.) used as a calibration model. The uncoated flexible insulations exhibited good thermal performance up to 35 W/sq cm. The use of a P.C.C. to protect these insulations at higher heating rates is described. The results from a computerized thermal analysis model describing thermal response of those materials subjected to the plasma arc conditions are included. Thermal and optical properties were determined including thermal conductivity for the rigid and flexible insulations and emissivity for the insulation fabrics. These properties were utilized to calculate the thermal performance of the rigid and flexible insulations at the maximum heating rate.

  6. Method for producing metal oxide aerogels having densities less than 0.02 g/cc

    DOEpatents

    Tillotson, Thomas M.; Poco, John F.; Hrubesh, Lawrence W.; Thomas, Ian M.

    1994-01-01

    A two-step method is described for making transparent aerogels which have a density of less than 0.003 g/cm.sup.3 to those with a density of more than 0.8 g/cm.sup.3, by a sol/gel process and supercritical extraction. Condensed metal oxide intermediate made with purified reagents can be diluted to produce stable aerogels with a density of less than 0.02 g/cm.sup.3. High temperature, direct supercritical extraction of the liquid phase of the gel produces hydrophobic aerogels which are stable at atmospheric moisture conditions. Monolithic, homogeneous silica aerogels with a density of less than 0.02 to higher than 0.8 g/cm.sup.3, with high thermal insulation capacity, improved mechanical strength and good optical transparency, are described.

  7. Method for producing metal oxide aerogels having densities less than 0. 02 g/cc

    DOEpatents

    Tillotson, T.M.; Poco, J.F.; Hrubesh, L.W.; Thomas, I.M.

    1994-01-04

    A two-step method is described for making transparent aerogels which have a density of less than 0.003 g/cm[sup 3] to those with a density of more than 0.8 g/cm[sup 3], by a sol/gel process and supercritical extraction. Condensed metal oxide intermediate made with purified reagents can be diluted to produce stable aerogels with a density of less than 0.02 g/cm[sup 3]. High temperature, direct supercritical extraction of the liquid phase of the gel produces hydrophobic aerogels which are stable at atmospheric moisture conditions. Monolithic, homogeneous silica aerogels with a density of less than 0.02 to higher than 0.8 g/cm[sup 3], with high thermal insulation capacity, improved mechanical strength and good optical transparency, are described. 7 figures.

  8. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, R.W.

    1996-09-17

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1,000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1,050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

  9. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, R.W.

    1995-12-19

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes{<=}1000{angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

  10. Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, R.W.

    1998-04-28

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes {<=}1000 {angstrom}, and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050 C to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors. 8 figs.

  11. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, Richard W.

    1995-01-01

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes.ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

  12. Organic carbon aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, Richard W.

    1998-04-28

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000 .ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

  13. Organic aerogels from the sol-gel polymerization of phenolic-furfural mixtures

    DOEpatents

    Pekala, Richard W.

    1996-01-01

    The sol-gel polymerization of a phenolic-furfural mixture in dilute solution leads to a highly cross-linked network that can be supercritically dried to form a high surface area foam. These porous materials have cell/pore sizes .ltoreq.1000.ANG., and although they are dark brown in color, they can be classified as a new type of aerogel. The phenolic-furfural aerogel can be pyrolyzed in an inert atmosphere at 1050.degree. C. to produce carbon aerogels. This new aerogel may be used for thermal insulation, chromatographic packing, water filtration, ion-exchange, and carbon electrodes for energy storage devices, such as batteries and double-layer capacitors.

  14. Design of metallic foams as insulation in thermal protection systems

    NASA Astrophysics Data System (ADS)

    Zhu, Huadong

    Metallic foams are novel materials that can be used as thermal insulation in many applications. The low volume fraction of solid, the small cell size and the low conductivity of enclosed gases limit the heat flow in foams. Varying the density, geometry and or material composition from point to point within the foam, one can produce functionally graded foams that may insulate more efficiently. The goal of this research is to investigate the use of functionally graded metal foam in thermal protection systems (TPS) for reusable launch vehicles. First, the effective thermal conductivity of the foam is derived based on a simple cubic unit cell model. Then two problems under steady state of heat transfer have been considered. The first one is the optimization of functionally graded foam insulation for minimum heat transmitted to the structure and the second is minimizing the mass of the functionally graded foam insulation for a given aerodynamic heating. In both cases optimality conditions are derived in closed-form, and numerical methods are used to solve the resulting differential equations to determine the optimal grading of the foam. In order to simplify the analysis the insulation was approximated by finite layers of uniform foams when studying the transient heat transfer case. The maximum structure temperature was minimized by varying the solidity profile for a given total thickness and mass. The principles that govern the design of TPS for transient conditions were identified. To take advantage of the load bearing ability of metallic foams, an integrated sandwich TPS/structure with metallic foam core is proposed. Such an integrated TPS will insulate the vehicle interior from aerodynamic heating as well as carry the primary vehicle loads. Thermal-structural analysis of integrated sandwich TPS panel subjected to transient heat conduction is developed to evaluate their performances. The integrated TPS design is compared with a conventional fibrous Safill TPS design

  15. Reusable Thermal Barrier for Insulation Gaps

    NASA Technical Reports Server (NTRS)

    Saladee, C. E.

    1985-01-01

    Filler composed of resilient, heat-resistant materials. Thermal barrier nestles snugly in gap between two tiles with minimal protrusion beyond faces of surrounding tiles. When removed from gap, barrier springs back to nearly original shape. Developed for filling spaces between tiles on Space Shuttle, also used in furnaces and kilns.

  16. Performance of Thermal Insulation Containing Microencapsulated Phase Change Material

    SciTech Connect

    Kosny, Jan; Yarbrough, David; Syed, Azam M

    2007-01-01

    The objective of this study is dynamic thermal performance microencapsulated phase change material (PCM) blended with loose-fill cellulose insulation. Dynamic hot-box testing and heat-flux measurements have been made for loose-fill cellulose insulation with and without uniformly distributed microencapsulated PCM. The heat flux measurements were made with a heat-flow-meter (HFM) apparatus built in accordance with ASTM C 518. Data were obtained for 1.6 lb{sub m}/ft{sup 3} cellulose insulation containing 0 to 40 wt% PCM. Heat-flux data resulting from a rapid increase in the temperature on one side of a test specimen initially at uniform temperature were analyzed to access the effect of PCM on total heat flow. The heat flux was affected by the PCM for about 100 minutes after the temperature increase. The total heat flow during this initial period decreased linearly with PCM content from 6.5 Btu/ft{sup 2} at 0% PCM to 0.89 Btu/ft{sup 2} for 40 wt% PCM. The cellulose insulation with PCM discharged heat faster than the untreated cellulose when the hot-side temperature of the test specimen was reduced. In addition, hot-box apparatus built in accordance with ASTM C 1363 was utilized for dynamic hot-box testing of a wood stud wall assembly containing PCM-enhanced cellulose insulation. Experimental data obtained for wood-frame wall cavities containing cellulose insulation with PCM was compared with results obtained from cavities containing only cellulose insulation.

  17. Thin Thermal-Insulation Blankets for Very High Temperatures

    NASA Technical Reports Server (NTRS)

    Choi, Michael K.

    2003-01-01

    Thermal-insulation blankets of a proposed type would be exceptionally thin and would endure temperatures up to 2,100 C. These blankets were originally intended to protect components of the NASA Solar Probe spacecraft against radiant heating at its planned closest approach to the Sun (a distance of 4 solar radii). These blankets could also be used on Earth to provide thermal protection in special applications (especially in vacuum chambers) for which conventional thermal-insulation blankets would be too thick or would not perform adequately. A blanket according to the proposal (see figure) would be made of molybdenum, titanium nitride, and carbon- carbon composite mesh, which melt at temperatures of 2,610, 2,930, and 2,130 C, respectively. The emittance of molybdenum is 0.24, while that of titanium nitride is 0.03. Carbon-carbon composite mesh is a thermal insulator. Typically, the blanket would include 0.25-mil (.0.00635-mm)-thick hot-side and cold-side cover layers of molybdenum. Titanium nitride would be vapor-deposited on both surfaces of each cover layer. Between the cover layers there would be 10 inner layers of 0.15-mil (.0.0038-mm)-thick molybdenum with vapor-deposited titanium nitride on both sides of each layer. The thickness of each titanium nitride coat would be about 1,000 A. The cover and inner layers would be interspersed with 0.25-mil (0.00635-mm)-thick layers of carbon-carbon composite mesh. The blanket would have total thickness of 4.75 mils (approximately equal to 0.121 mm) and an areal mass density of 0.7 kilograms per square meter. One could, of course, increase the thermal- insulation capability of the blanket by increasing number of inner layers (thereby unavoidably increasing the total thickness and mass density).

  18. Layered Thermal Insulation Systems for Industrial and Commercial Applications

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.

    2015-01-01

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

  19. Lightweight Thermal Insulation for a Liquid-Oxygen Tank

    NASA Technical Reports Server (NTRS)

    Willen, G. Scott; Lock, Jennifer; Nieczkoski, Steve

    2005-01-01

    A proposed lightweight, reusable thermal-insulation blanket has been designed for application to a tank containing liquid oxygen, in place of a non-reusable spray-on insulating foam. The blanket would be of the multilayer-insulation (MLI) type and equipped with a pressure-regulated nitrogen purge system. The blanket would contain 16 layers in two 8-layer sub-blankets. Double-aluminized polyimide 0.3 mil (.0.008 mm) thick was selected as a reflective shield material because of its compatibility with oxygen and its ability to withstand ionizing radiation and high temperature. The inner and outer sub-blanket layers, 1 mil (approximately equals 0.025 mm) and 3 mils (approximately equals 0.076 mm) thick, respectively, would be made of the double-aluminized polyimide reinforced with aramid. The inner and outer layers would provide structural support for the more fragile layers between them and would bear the insulation-to-tank attachment loads. The layers would be spaced apart by lightweight, low-thermal-conductance netting made from polyethylene terephthalate.

  20. Water Intercalation for Seamless, Electrically Insulating, and Thermally Transparent Interfaces.

    PubMed

    Wang, Yanlei; Xu, Zhiping

    2016-01-27

    The interface between functional nanostructures and host substrates is of pivotal importance in the design of their nanoelectronic applications because it conveys energy and information between the device and environment. We report here an interface-engineering approach to establish a seamless, electrically insulating, while thermally transparent interface between graphene and metal substrates by introducing water intercalation. Molecular dynamics simulations and first-principles calculations are performed to demonstrate this concept of design, showing that the presence of the interfacial water layer helps to unfold wrinkles formed in the graphene membrane, insulate the electronic coupling between graphene and the substrate, and elevate the interfacial thermal conductance. The findings here lay the ground for a new class of nanoelectronic setups through interface engineering, which could lead to significant improvement in the performance of nanodevices, such as the field-effect transistors. PMID:26720217

  1. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1996-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  2. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, M.T.; Basaran, O.A.; Kollie, T.G.; Weaver, F.J.

    1996-01-02

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm{sup 3} and an external surface area in the range of about 90 to 600 m{sup 2}/g is described. The silica powders are prepared by reacting a tetraalkyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders. 2 figs.

  3. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1995-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2/ g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  4. Silica powders for powder evacuated thermal insulating panel and method

    DOEpatents

    Harris, Michael T.; Basaran, Osman A.; Kollie, Thomas G.; Weaver, Fred J.

    1994-01-01

    A powder evacuated thermal insulating panel using generally spherical and porous silica particles of a median size less than about 100 nanometers in diameter, a pour packing density of about 0.4 to 0.6 g/cm.sup.3 and an external surface area in the range of about 90 to 600 m.sup.2 /g is described. The silica powders are prepared by reacting a tetraakyl silicate with ammonia and water in an alcohol solvent, distilling the solution after the reaction to remove the ammonia and recover the alcohol. The resulting aqueous slurry was dried, ball-milled, and dried again to provide the silica particles with defined internal and external porosity. The nanometer size and the large external surface area of the silica particles along with the internal and external porosity of the silica particles provide powder evacuated thermal insulating panels with significantly higher R-values than obtainable using previously known silica powders.

  5. Coated Aerogel Beads

    NASA Technical Reports Server (NTRS)

    Littman, Howard (Inventor); Plawsky, Joel L. (Inventor); Paccione, John D. (Inventor)

    2014-01-01

    Methods and apparatus for coating particulate material are provided. The apparatus includes a vessel having a top and a bottom, a vertically extending conduit having an inlet in the vessel and an outlet outside of the vessel, a first fluid inlet in the bottom of the vessel for introducing a transfer fluid, a second fluid inlet in the bottom of the vessel for introducing a coating fluid, and a fluid outlet from the vessel. The method includes steps of agitating a material, contacting the material with a coating material, and drying the coating material to produce a coated material. The invention may be adapted to coat aerogel beads, among other materials. A coated aerogel bead and an aerogel-based insulation material are also disclosed.

  6. Thermal insulation of pipelines by foamed glass-ceramic

    NASA Astrophysics Data System (ADS)

    Apkaryan, A. S.; Kudyakov, A. I.

    2015-01-01

    Based on broken glass, clay and organic additives granular insulating glass crystalline material and technology of its receipt are developed. The regularities of the effect of composition and firing temperature on the properties of the granules are specified. The resulting granular thermally insulating material is produced with a bulk density of 260-280 kg/m3 pellet strength - 1.74 MPa, thermal conductivity - 0.075 W/m °C, water absorption - 2.6 % by weight. The effect of the basic physical characteristics of the components of the charge on the process of pore formation is studied. According to the research results, basic parameters affecting the sustainability of the swelling glass are specified. Rational charge composition, thermal and gas synthesis mode are chosen so that the partial pressure of gases is below the surface tension of the melt. This enables the formation of granules with small closed pores and vitrified surface. The article is the result of studies on the application of materials for pipe insulation of heating mains with foamed glass ceramics.

  7. Thermal coupon testing of Load-Bearing Multilayer Insulation

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Heckle, K. W.; Hurd, J.

    2014-01-01

    Advanced liquid hydrogen storage concepts being considered for long duration space travel incorporate refrigeration systems and cryocoolers to lower the heat load. Using a refrigeration loop to intercept the energy flowing through MLI to a liquid hydrogen tank at a temperature between the environment and the liquid hydrogen can lower the heat load on the propellant system by as much as 50%. However, the refrigeration loop requires structural integration into the MLI. Use of a more traditional concept of MLI underneath this refrigeration loop requires that a structural system be put in place to support the loop. Such structures, even when thermally optimized, present a relatively large parasitic heat load into the tank. Through NASA small business innovation research funding, Quest Thermal Group and Ball Aerospace have been developing a structural MLI based insulation system. These systems are designed with discrete polymeric spacers between reflective layers instead of either dacron or silk netting. The spacers (or posts) have an intrinsic structural capability that is beyond that of just supporting the internal insulation mechanical loads. This new MLI variant called Load Bearing MLI (LB-MLI) has been developed specifically for the application of supporting thermal shields within the insulation system. Test articles (coupons) of the new LB-MLI product were fabricated for thermal performance testing using liquid nitrogen at Kennedy Space Center (KSC) and using cryocooler based calorimetry at Florida State University. The test results and analysis are presented. Thermal models developed for correlation with the thermal testing results both at KSC and testing that was performed at Florida State University are also discussed.

  8. Thermographic inspection of external thermal insulation systems with mechanical fixing

    NASA Astrophysics Data System (ADS)

    Simões, Nuno; Simões, Inês; Serra, Catarina; Tadeu, António

    2015-05-01

    An External Thermal Insulation Composite System (ETICS) kit may include anchors to mechanically fix the insulation product onto the wall. Using this option increases safety when compared to a simple bonded solution, however, it is more expensive and needs higher labor resources. The insulation product is then coated with rendering, which applied to the insulation material without any air gap. The rendering comprises one or more layers of coats with an embedded reinforcement. The most common multi-coat rendering system presents a base coat applied directly to the insulation product with a glass fiber mesh as reinforcement, followed by a second base coat, before a very thin coat (key coat) that prepares the surface to receive the finishing and decorative coat. The thickness of the rendering system may vary between around 5 to 10 mm. The higher thicknesses may be associated with a reinforcement composed by two layers of glass fiber mesh. The main purpose of this work is to apply infrared thermography (IRT) techniques to 2 ETICS solution (single or double layer of glass fiber mesh) and evaluate its capability in the detection of anchors. The reliability of IRT was tested using an ETICS configuration of expanded cork boards and a rendering system with one or two layers of glass fiber mesh. An active thermography approach was performed in laboratory conditions, in transmission and reflection mode. In the reflection mode halogen lamps and air heater were employed as the thermal stimulus. Air heater was also the source used in the transmission mode tests. The resulting data was processed in both time and frequency domains. In this last approach, phase contrast images were generated and studied.

  9. Study of multilayered insulation pipe penetration. Thermal acoustic oscillation

    NASA Technical Reports Server (NTRS)

    Lovin, J. K.

    1974-01-01

    Tests were conducted to determine the net heat leak to a source of liquid nitrogen caused by a metal penetration through the blanket of multilayer insulation. The conditions under which the tests were conducted are described. A graph of the theoretical and experimental temperature distribution is developed for comparison. The variables involved in the computer program to process the data are defined. A study was conducted to develop analytical methods for predicting the effect and magnitudes of thermoacoustic oscillations on the penetration heat leak to cryogens. The oscillations develop as a result of large thermal gradients imposed on a compressible fluid. The predominant amplitudes and frequencies of the thermal acoustic oscillations were investigated.

  10. Martian hydrogeology sustained by thermally insulating gas and salt hydrates

    NASA Astrophysics Data System (ADS)

    Kargel, Jeffrey S.; Furfaro, Roberto; Prieto-Ballesteros, Olga; Rodriguez, J. Alexis P.; Montgomery, David R.; Gillespie, Alan R.; Marion, Giles M.; Wood, Stephen E.

    2007-11-01

    Numerical simulations and geologic studies suggest that high thermal anomalies beneath, within, and above thermally insulating layers of buried hydrated salts and gas hydrates could have triggered and sustained hydrologic processes on Mars, producing or modifying chaotic terrains, debris flows, gullies, and ice-creep features. These simulations and geologic examples suggest that thick hydrate deposits may sustain such geothermal anomalies, shallow ground-water tables, and hydrogeologic activity for eons. The proposed mechanism may operate and be self-reinforcing even in today's cold Martian climate without elevated heat flux.

  11. Cylindrical boiloff calorimeters for testing of thermal insulation systems

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Johnson, W. L.; Meneghelli, B. J.; Coffman, B. E.

    2015-12-01

    Cryostats have been developed and standardized for laboratory testing of thermal insulation systems in a cylindrical configuration. Boiloff calorimetry is the measurement principle for determining the effective thermal conductivity (ke) and heat flux (q) of a test specimen at a fixed environmental condition (boundary temperatures, cold vacuum pressure, and residual gas composition). Through its heat of vaporization, liquid nitrogen serves as the energy meter, but the design is adaptable for various cryogens. The main instrument, Cryostat-100, is thermally guarded and directly measures absolute thermal performance. A cold mass assembly and all fluid and instrumentation feedthroughs are suspended from a lid of the vacuum canister; and a custom lifting mechanism allows the assembly and specimen to be manipulated easily. Each of three chambers is filled and vented through a single feedthrough for minimum overall heat leakage. The cold mass design precludes direct, solid-conduction heat transfer (other than through the vessel's outer wall itself) from one liquid volume to another, which is critical for achieving very low heat measurements. The cryostat system design details and test methods are discussed, as well as results for select thermal insulation materials. Additional cylindrical boiloff calorimeters and progress toward a liquid hydrogen apparatus are also discussed.

  12. Partitioned airs at microscale and nanoscale: thermal diffusivity in ultrahigh porosity solids of nanocellulose

    PubMed Central

    Sakai, Koh; Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2016-01-01

    High porosity solids, such as plastic foams and aerogels, are thermally insulating. Their insulation performance strongly depends on their pore structure, which dictates the heat transfer process in the material. Understanding such a relationship is essential to realizing highly efficient thermal insulators. Herein, we compare the heat transfer properties of foams and aerogels that have very high porosities (97.3–99.7%) and an identical composition (nanocellulose). The foams feature rather closed, microscale pores formed with a thin film-like solid phase, whereas the aerogels feature nanoscale open pores formed with a nanofibrous network-like solid skeleton. Unlike the aerogel samples, the thermal diffusivity of the foam decreases considerably with a slight increase in the solid fraction. The results indicate that for suppressing the thermal diffusion of air within high porosity solids, creating microscale spaces with distinct partitions is more effective than directly blocking the free path of air molecules at the nanoscale. PMID:26830144

  13. Partitioned airs at microscale and nanoscale: thermal diffusivity in ultrahigh porosity solids of nanocellulose.

    PubMed

    Sakai, Koh; Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2016-01-01

    High porosity solids, such as plastic foams and aerogels, are thermally insulating. Their insulation performance strongly depends on their pore structure, which dictates the heat transfer process in the material. Understanding such a relationship is essential to realizing highly efficient thermal insulators. Herein, we compare the heat transfer properties of foams and aerogels that have very high porosities (97.3-99.7%) and an identical composition (nanocellulose). The foams feature rather closed, microscale pores formed with a thin film-like solid phase, whereas the aerogels feature nanoscale open pores formed with a nanofibrous network-like solid skeleton. Unlike the aerogel samples, the thermal diffusivity of the foam decreases considerably with a slight increase in the solid fraction. The results indicate that for suppressing the thermal diffusion of air within high porosity solids, creating microscale spaces with distinct partitions is more effective than directly blocking the free path of air molecules at the nanoscale. PMID:26830144

  14. Partitioned airs at microscale and nanoscale: thermal diffusivity in ultrahigh porosity solids of nanocellulose

    NASA Astrophysics Data System (ADS)

    Sakai, Koh; Kobayashi, Yuri; Saito, Tsuguyuki; Isogai, Akira

    2016-02-01

    High porosity solids, such as plastic foams and aerogels, are thermally insulating. Their insulation performance strongly depends on their pore structure, which dictates the heat transfer process in the material. Understanding such a relationship is essential to realizing highly efficient thermal insulators. Herein, we compare the heat transfer properties of foams and aerogels that have very high porosities (97.3-99.7%) and an identical composition (nanocellulose). The foams feature rather closed, microscale pores formed with a thin film-like solid phase, whereas the aerogels feature nanoscale open pores formed with a nanofibrous network-like solid skeleton. Unlike the aerogel samples, the thermal diffusivity of the foam decreases considerably with a slight increase in the solid fraction. The results indicate that for suppressing the thermal diffusion of air within high porosity solids, creating microscale spaces with distinct partitions is more effective than directly blocking the free path of air molecules at the nanoscale.

  15. THERMAL INSULATION FROM LIGNIN-DERIVED CARBON FIBERS

    SciTech Connect

    Albers, Tracy; Chen, Chong; Eberle, Cliff; Webb, Daniel C

    2014-01-01

    Oak Ridge National Laboratory (ORNL) and GrafTech International Holdings Inc. (GrafTech) have collaborated to develop and demonstrate the performance of high temperature thermal insulation prototypes made from lignin-based carbon fibers (LBCF). This was the first reported production of LBCF or resulting products at scale > 1 kg. The results will potentially lead to the first commercial application of LBCF. The goal of the commercial application is to replace expensive, foreign-sourced isotropic pitch carbon fibers with lower cost carbon fibers made from a domestically sourced, bio-derived (renewable) feedstock. LBCF can help resolve supply chain vulnerability and reduce the production cost for high temperature thermal insulation as well as create US jobs. The performance of the LBCF prototypes was measured and found to be comparable to that of the current commercial product. During production of the insulation prototypes, the project team demonstrated lignin compounding/pelletization, fiber production, heat treatment, and compositing at scales far surpassing those previously demonstrated in LBCF R&D or production.

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

    NASA Technical Reports Server (NTRS)

    Johnson, Wesley L.

    2011-01-01

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

  17. Thermal performance of fiberglass and cellulose attic insulations

    SciTech Connect

    Wilkes, K.E.; Childs, P.W.

    1992-10-01

    A series of experiments has been completed on the thermal performance of fiberglass and cellulose attic insulations under winter conditions using an attic test module in a guarded hot box facility. Experiments with one type of loose-fill fiberglass insulation showed that the thermal resistance at large temperature differences (70 to 76{degrees}F) was about 35 to 50% less than at small temperature differences. The additional heat flow, attributed to natural convection, was effectively eliminated by applying a covering of fiberglass batts or a combination of a polyethylene film and fiberglass blankets. No significant convection was found either with fiberglass batts or with one type of loose-fill cellulose. Using the experimental data along with an attic model, the additional energy costs due to convection in the coldest climate investigated were estimated to be $0.025/ft{sup 2}yr to $0.028/ft{sup 2}yr at the R-19 level and $0.014/ft{sup 2}yr at the R-38 level. For the same conditions, annual energy savings due to upgrading insulation from the R-19 to the R-38 level were estimated to be $0.046/ft{sup 2}yr to $0.070/ft{sup 2}yr.

  18. Thermal Performance Evaluation of Walls with Gas Filled Panel Insulation

    SciTech Connect

    Shrestha, Som S.; Desjarlais, Andre Omer; Atchley, Jerald Allen

    2014-11-01

    Gas filled insulation panels (GFP) are very light weight and compact (when uninflated) advanced insulation products. GFPs consist of multiple layers of thin, low emittance (low-e) metalized aluminum. When expanded, the internal, low-e aluminum layers form a honeycomb structure. These baffled polymer chambers are enveloped by a sealed barrier and filled with either air or a low-conductivity gas. The sealed exterior aluminum foil barrier films provide thermal resistance, flammability protection, and properties to contain air or a low conductivity inert gas. This product was initially developed with a grant from the U.S. Department of Energy. The unexpanded product is nearly flat for easy storage and transport. Therefore, transportation volume and weight of the GFP to fill unit volume of wall cavity is much smaller compared to that of other conventional insulation products. This feature makes this product appealing to use at Army Contingency Basing, when transportation cost is significant compared to the cost of materials. The objective of this study is to evaluate thermal performance of walls, similar to those used at typical Barracks Hut (B-Hut) hard shelters, when GFPs are used in the wall cavities. Oak Ridge National Laboratory (ORNL) tested performance of the wall in the rotatable guarded hotbox (RGHB) according to the ASTM C 1363 standard test method.

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

    PubMed Central

    Zhou, Ao; Wong, Kwun-Wah

    2014-01-01

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

  20. Thermal insulating concrete wall panel design for sustainable built environment.

    PubMed

    Zhou, Ao; Wong, Kwun-Wah; Lau, Denvid

    2014-01-01

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

  1. Chrysotile asbestos exposure in the manufacturing of thermal insulating boards.

    PubMed

    Bhagia, L J; Vyas, J B; Shaikh, M I; Dodia, S L

    2010-08-01

    Exposure to asbestos fibers has been extensively studied in milling, mining of asbestos fibers, and in industries manufacturing asbestos-cement sheets, pipes, etc. However, very few studies have been reported in asbestos textiles, brake lining workers, and insulation products. In the present investigation, chrysotile exposure monitoring was carried out in a small thermal insulating boards manufacturing facility. Twenty-eight samples were analyzed from various locations like feeding of raw materials, weighing, pressing, machine grinding, and hand finishing of final products. Twenty-five percent of the samples were found to be above ACGIH TLV of 0.1 fibers per milliliter. However, mean fiber concentrations were found to be lower than 0.1 fibers per milliliter, except for the process of feeding of raw materials where the mean fiber concentration was 0.1087+/-0.0631 fibers per milliliter. PMID:19626449

  2. X-Aerogels for Structural Components and High Temperature Applications

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Future NASA missions and space explorations rely on the use of materials that are strong ultra lightweight and able to withstand extreme temperatures. Aerogels are low density (0.01-0.5 g/cu cm) high porosity materials that contain a glass like structure formed through standard sol-gel chemistry. As a result of these structural properties, aerogels are excellent thermal insulators and are able to withstand temperatures in excess of l,000 C. The open structure of aerogels, however, renders these materials extremely fragile (fracturing at stress forces less than 0.5 N/sq cm). The goal of NASA Glenn Research Center is to increase the strength of these materials by templating polymers and metals onto the surface of an aerogel network facilitating the use of this material for practical applications such as structural components of space vehicles used in exploration. The work this past year focused on two areas; (1) the research and development of new templated aerogels materials and (2) process development for future manufacturing of structural components. Research and development occurred on the production and characterization of new templating materials onto the standard silica aerogel. Materials examined included polymers such as polyimides, fluorinated isocyanates and epoxies, and, metals such as silver, gold and platinum. The final properties indicated that the density of the material formed using an isocyanate is around 0.50 g/cc with a strength greater than that of steel and has low thermal conductivity. The process used to construct these materials is extremely time consuming and labor intensive. One aspect of the project involved investigating the feasibility of shortening the process time by preparing the aerogels in the templating solvent. Traditionally the polymerization used THF as the solvent and after several washes to remove any residual monomers and water, the solvent around the aerogels was changed to acetonitrile for the templating step. This process

  3. A Study on High Thermal Conductive Insulation for Claw Teeth Motors

    NASA Astrophysics Data System (ADS)

    Yoshitake, Yuichiro; Obata, Koji; Enomoto, Yuji; Okabe, Yoshiaki

    To increase the power density of motors in a wide range of fields from home appliance to power industry, we proposed two new high thermal conductive insulation systems for the motors. They were a glass cross insulation system and a resin coated insulation system without forced cooling devices such as a cooling fan. Their thermal and insulation characteristics were measured and analyzed, and optimum thermal conductive structures for claw teeth motors were discussed through robust design and thermal network analysis. Experiment on prototype motors with the highest thermal conductive epoxy resin (5 W/mK) and the proposed systems, revealed that the temperature rise of motor coils was decreased; their temperature reached 73 % of that of the motor coils with standard insulation and normal resin (0.6 W/mK). Furthermore, partial discharge inception voltage (PDIV) and breakdown voltage (BDV) were measured, and we verified that resin coated insulation motors could withstand as high a voltage as normal insulation motors.

  4. Nanoporous Carbon Monoliths with Tunable Thermal Insulation and Mechanical Properties.

    PubMed

    Wang, Xiaopeng; Chen, Fenghua; Luo, Zhenhua; Li, Hao; Zhao, Tong

    2016-01-01

    In this work, nanoscale porous carbon monoliths, with excellent compressive strength and thermal insulation, were obtained with a simple method of carbonizing cured phenol-formaldehyde resin/poly(methyl methacrylate) blends. Apparent density, pore size and morphology of the carbon monoliths were tailored by changing the composition, curing process and carbonization temperature. The continuous nanopores played a key role in enhancing mechanical and thermal performance of the carbon materials. When PMMA concentration was 25%, apparent density and thermal conductivity of the nanoporous carbonaceous monoliths were obtained as low as 1.07 g · cm⁻³ and 0.42 W/(m · K), decreasing by 29.4% and 35.4% than that of carbonaceous monoliths obtained from pure PF; while compressive strength of the nanoporous carbonaceous monoliths was as high as 34 MPa, which was improved over five times than that of pure PF carbon monoliths. PMID:27398592

  5. High Temperature Aerogels in the Al2O3-SiO2 System

    NASA Technical Reports Server (NTRS)

    Hurwitz, Frances I.; Aranda, Denisse V.; Gallagher, Meghan E.

    2008-01-01

    Al2O3-SiO2 aerogels are of interest as constituents of thermal insulation systems for use at high temperatures. Al2O3 and mullite aerogels are expected to crystallize at higher temperatures than their SiO2 counterparts, hence avoiding the shrinkages that accompany the formation of lower temperature SiO2 phases and preserving pore structures into higher temperature regimes. The objective of this work is to determine the influence of processing parameters on shrinkage, gel structure (including surface area, pore size and distribution) and pyrolysis behavior.

  6. Aerogel waveplates.

    PubMed

    Bhupathi, Pradeep; Hwang, Jungseek; Martin, Rodica M; Blankstein, Jackson; Jaworski, Lukas; Mulders, Norbert; Tanner, David B; Lee, Yoonseok

    2009-06-22

    Optical transmission measurements were made on 98% porosity silica aerogel samples under various degrees of uniaxial strain. Uniaxially compressed aerogels exhibit large birefringence, proportional to the amount of compression, up to the 15% strain studied. The birefringence is mostly reversible and reproducible through multiple compression-decompression cycles. Our study demonstrates that uniaxially strained high porosity aerogels can be used as tunable waveplates in a broad spectral range. PMID:19550455

  7. Graphene aerogels

    DOEpatents

    Pauzauskie, Peter J; Worsley, Marcus A; Baumann, Theodore F; Satcher, Jr., Joe H; Biener, Juergen

    2015-03-31

    Graphene aerogels with high conductivity and surface areas including a method for making a graphene aerogel, including the following steps: (1) preparing a reaction mixture comprising a graphene oxide suspension and at least one catalyst; (2) curing the reaction mixture to produce a wet gel; (3) drying the wet gel to produce a dry gel; and (4) pyrolyzing the dry gel to produce a graphene aerogel. Applications include electrical energy storage including batteries and supercapacitors.

  8. Study on Thermal and Mechanical Properties of EPDM Insulation

    NASA Astrophysics Data System (ADS)

    Zhang, Zhong-Shui; Xu, Jin-Sheng; Chen, Xiong; Jiang, Jing

    As the most common insulation material of solid rocket motors, thermal and mechanical properties of ethylene propylene diene monomer (EPDM) composite are inspected in the study. Referring to the results of thermogravimetric analysis (TGA), composition and morphology of EPDM composite in different thermal degradation degree are investigated by scanning electron microscope (SEM) to inspect the mechanism of thermal insulation. Mechanical properties of EPDM composite in the state of pyrolysis are investigated by uniaxial tensile tests. At the state of initial pyrolysis, composite belongs to the category of hyperelastic-viscoelastic material. The tendency of tensile strength increased and elongation decreased with increasing of heating temperature. Composite behaves as the linear rule at the state of late pyrolysis, which belongs to the category of bittle. The elasticity modulus of curves are almost the same while the heating temperature ranges from 200°C to 300°C, and then gradually go down. The tensile strength of pyrolytic material reach the highest at the heating temperature of 300°C, and the virgin material has the largest elongation.

  9. Analysis of thermal performance of penetrated multi-layer insulation

    NASA Technical Reports Server (NTRS)

    Foster, Winfred A., Jr.; Jenkins, Rhonald M.; Yoo, Chai H.; Barrett, William E.

    1988-01-01

    Results of research performed for the purpose of studying the sensitivity of multi-layer insulation blanket performance caused by penetrations through the blanket are presented. The work described in this paper presents the experimental data obtained from thermal vacuum tests of various penetration geometries similar to those present on the Hubble Space Telescope. The data obtained from these tests is presented in terms of electrical power required sensitivity factors referenced to a multi-layer blanket without a penetration. The results of these experiments indicate that a significant increase in electrical power is required to overcome the radiation heat losses in the vicinity of the penetrations.

  10. Study of thermal insulation for airborne liquid hydrogen fuel tanks

    NASA Technical Reports Server (NTRS)

    Ruccia, F. E.; Lindstrom, R. S.; Lucas, R. M.

    1978-01-01

    A concept for a fail-safe thermal protection system was developed. From screening tests, approximately 30 foams, adhesives, and reinforcing fibers using 0.3-meter square liquid nitrogen cold plate, CPR 452 and Stafoam AA1602, both reinforced with 10 percent by weight of 1/16 inch milled OCF Style 701 Fiberglas, were selected for further tests. Cyclic tests with these materials in 2-inch thicknesses bonded on a 0.6-meter square cold plate with Crest 7410 adhesive systems, were successful. Zero permeability gas barriers were identified and found to be compatible with the insulating concept.

  11. Low temperature thermal properties of composite insulation systems

    NASA Astrophysics Data System (ADS)

    Fabian, P. E.; Bauer-McDaniel, T. S.; Reed, R. P.

    The thermal contraction and thermal conductivity of candidate composite insulation systems for the International Thermonuclear Experimental Reactor toroidal field coils were measured from 295 to 4 K. Matrix materials consisted of a diglycidyl ether of bisphenol-A epoxy suitable for vacuum impregnation, a tetrafunctional epoxy suitable for pre-impregnation, a polyimide system produced by a high-pressure laminating process, and a bismaleimide system. These matrix materials were combined with S-2 glass fabric and various barrier systems, such as ceramic and organic coatings, polyimide film and mica/glass. Thermal contraction was measured by the strain gauge method in which strain gauges are attached directly to the specimen. The thermal contraction in the through-thickness direction was different at 4 K for each resin system and changed slightly with the addition of electrical barriers. The thermal conductivity of the materials, with and without the electrical barriers, was similar at 4 K, but more distinctive at higher temperatures. The systems with the ceramic coatings exhibited the highest thermal conductivities at all temperatures.

  12. Thermal analysis of low layer density multilayer insulation test results

    NASA Astrophysics Data System (ADS)

    Johnson, Wesley

    2012-06-01

    Investigation of the thermal performance of low layer density multilayer insulations is important for designing long-duration space exploration missions involving the storage of cryogenic propellants. Theoretical calculations show an analytical optimal layer density. However, the appropriate test data by which to evaluate these calculations have been only recently obtained. As part of a recent research project, NASA procured several multilayer insulation test articles for calorimeter testing. These blanket-type test articles were configured to allow a layer density variation from 0.5 to 2.5 layers per millimeter. The coupon testing was completed by the Cryogenics Test Laboratory at Kennedy Space Center using the cylindrical Cryostat-100 apparatus. The results show insulation properties as a function of layer density for multiple points. Overlaying these new results with data from the literature reveals an optimum layer density; however, the value is approximately twice as high as predicted. The data also show that the transition region between high vacuum and no vacuum is dependent on the spacing of the reflective layers. These results aid in the understanding of the performance parameters of MLI and help to complete the body of literature on the topic.

  13. Thermal Performance of Exterior Insulation and Finish Systems Containing Vacuum Insulation Panels

    SciTech Connect

    Childs, Kenneth W; Stovall, Therese K; Biswas, Kaushik; Carbary, Lawrence D

    2013-01-01

    A high-performance wall system is under development to improve wall thermal performance to a level of U-factor of 0.19 W/(m2 K) (R-30 [h ft2 F]/Btu) in a standard wall thickness by incorporating vacuum insulation panels (VIPs) into an exterior insulation finish system (EIFS). Such a system would be applicable to new construction and will offer a solution to more challenging retrofit situations as well. Multiple design options were considered to balance the need to protect theVIPs during construction and building operation, while minimizing heat transfer through the wall system. The results reported here encompass an indepth assessment of potential system performances including thermal modeling, detailed laboratory measurements under controlled conditions on the component, and system levels according to ASTM C518 (ASTM 2010). The results demonstrate the importance of maximizing the VIP coverage over the wall face. The results also reveal the impact of both the design and execution of system details, such as the joints between adjacent VIPs. The test results include an explicit modeled evaluation of the system performance in a clear wall.

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

    NASA Technical Reports Server (NTRS)

    Johnson, Wesley Louis

    2010-01-01

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

  15. Anomalous thermal expansion of Sb2Te3 topological insulator

    NASA Astrophysics Data System (ADS)

    Dutta, P.; Bhoi, D.; Midya, A.; Khan, N.; Mandal, P.; Shanmukharao Samatham, S.; Ganesan, V.

    2012-06-01

    We have investigated the temperature dependence of the linear thermal expansion along the hexagonal c axis (ΔL), in-plane resistivity (ρ), and specific heat (Cp) of the topological insulator Sb2Te3 single crystal. ΔL exhibits a clear anomaly in the temperature region 204-236 K. The coefficient of linear thermal expansion α decreases rapidly above 204 K, passes through a deep minimum at around 225 K, and then increases abruptly in the region 225-236 K. α is negative in the interval 221-228 K. The temperature dependence of both α and Cp can be described well by the Debye model from 2 to 290 K, excluding the region around the anomaly in α.

  16. Cryogenic Shrouds for Testing Thermal-Insulation Panels

    NASA Technical Reports Server (NTRS)

    Norris, Jeffrey; Carroll, Robert; Kirch, Charles

    2007-01-01

    Cryogenic shrouds have been designed and built for use in thermomechanical testing of samples of thermalinsulation panels on cryogenic vessels. In the original application for which these shrouds were specifically designed, the samples are representative of the large-area thermal-insulation panels on the space-shuttle external tanks that hold liquid hydrogen and liquid oxygen, and the purpose of the testing is to demonstrate the ability of bonded layers in the panels to resist delamination under a combination of applied uniaxial mechanical loads and realistic operational temperatures. Presumably, the shrouds and the tests performed by use of them could be modified to enable similar evaluation of thermomechanical properties of thermal-insulation panels for cryogenic vessels other than the external tanks of the space shuttles. The shrouds are required to enable maintenance of required temperatures on the inner and outer surfaces of the thermal-insulation-panel samples, to enable visual observation of the outer surfaces of the samples, and not to introduce any measurable loads into the panels. For each panel sample, there are two shrouds: one to be mounted on the inner surface (the surface that would be in contact with a tank containing a cryogenic liquid during normal use) and one to be mounted on the outer surface (the surface that would be exposed to ambient air or other warmer environment during normal use). The shrouds for testing specimens of thermal-insulation- panels for the liquid-hydrogen tank are made largely of titanium; the shrouds for testing specimens of thermal- insulation-panels for the liquid-oxygen tank are made largely of an aluminum- lithium alloy. The specific temperature requirements are the following: The inner shroud must make it possible to maintain a temperature of 321 degrees F (196 degrees C) [the approximate temperature of liquid nitrogen] or 453 F (about 269 C) [the approximate temperature of liquid helium] on the inner face of the

  17. Clothing resultant thermal insulation determined on a movable thermal manikin. Part I: effects of wind and body movement on total insulation.

    PubMed

    Lu, Yehu; Wang, Faming; Wan, Xianfu; Song, Guowen; Shi, Wen; Zhang, Chengjiao

    2015-10-01

    In this serial study, 486 thermal manikin tests were carried out to examine the effects of air velocity and walking speed on both total and local clothing thermal insulations. Seventeen clothing ensembles with different layers (i.e., one, two, or three layers) were selected for the study. Three different wind speeds (0.15, 1.55, 4.0 m/s) and three levels of walking speed (0, 0.75, 1.2 m/s) were chosen. Thus, there are totally nine different testing conditions. The clothing total insulation and local clothing insulation at different body parts under those nine conditions were determined. In part I, empirical equations for estimating total resultant clothing insulation as a function of the static thermal insulation, relative air velocity, and walking speed were developed. In part II, the local thermal insulation of various garments was analyzed and correction equations on local resultant insulation for each body part were developed. This study provides critical database for potential applications in thermal comfort study, modeling of human thermal strain, and functional clothing design and engineering. PMID:25597033

  18. Clothing resultant thermal insulation determined on a movable thermal manikin. Part I: effects of wind and body movement on total insulation

    NASA Astrophysics Data System (ADS)

    Lu, Yehu; Wang, Faming; Wan, Xianfu; Song, Guowen; Shi, Wen; Zhang, Chengjiao

    2015-10-01

    In this serial study, 486 thermal manikin tests were carried out to examine the effects of air velocity and walking speed on both total and local clothing thermal insulations. Seventeen clothing ensembles with different layers (i.e., one, two, or three layers) were selected for the study. Three different wind speeds (0.15, 1.55, 4.0 m/s) and three levels of walking speed (0, 0.75, 1.2 m/s) were chosen. Thus, there are totally nine different testing conditions. The clothing total insulation and local clothing insulation at different body parts under those nine conditions were determined. In part I, empirical equations for estimating total resultant clothing insulation as a function of the static thermal insulation, relative air velocity, and walking speed were developed. In part II, the local thermal insulation of various garments was analyzed and correction equations on local resultant insulation for each body part were developed. This study provides critical database for potential applications in thermal comfort study, modeling of human thermal strain, and functional clothing design and engineering.

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

    SciTech Connect

    Shiu, Kelvin K.

    1980-09-01

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

  20. Experimental evaluation of outer planets probe thermal insulation concepts

    NASA Technical Reports Server (NTRS)

    Grote, M. G.; Mezines, S. A.

    1976-01-01

    An experimental program was conducted to evaluate various thermal insulation concepts for use in the Outer Planets Probe (OPP) during entry and descent into the atmospheres of Jupiter, Saturn, and Uranus. Phenolic fiberglass honeycomb specimens representative of the OPP structure were packed and tested with various fillers: Thermal conductivity measurements were made over a temperature range of 300 K to 483 K and pressures from vacuum up to 10 atmospheres in helium and nitrogen gas environments. The conductivity results could not be fully explained so new test specimens were designed with improved venting characteristics, and tested to determine the validity of the original data. All of the conductivity data showed results that were substantially higher than expected. The original test data in helium were lower than the data from the redesigned specimens, probably due to inadequate venting of nitrogen gas from the original specimens. The thermal conductivity test results show only a marginal improvement in probe thermal protection performance for a filled honeycomb core compared to an unfilled core. In addition, flatwise tension tests showed a severe bond strength degradation due to the inclusion of either the powder or foam fillers. In view of these results, it is recommended that the baseline OPP design utilize an unfilled core.

  1. Thermal performance of a customized multilayer insulation (MLI)

    NASA Technical Reports Server (NTRS)

    Leonhard, K. E.

    1976-01-01

    The thermal performance of a LH2 tank on a shroudless vehicle was investigated. The 1.52 m (60 in) tank was insulated with 2 MLI blankets consisting of 18 double aluminized Mylar radiation shields and 19 silk net spacers. The temperature of outer space was simulated by using a cryoshroud which was maintained at near liquid hydrogen temperature. The heating effects of a payload were simulated by utilizing a thermal payload simulator (TPS) viewing the tank. The test program consisted of three major test categories: (1) null testing, (2) thermal performance testing of the tank installed MLI system, and (3) thermal testing of a customized MLI configuration. TPS surface temperatures during the null test were maintained at near hydrogen temperature and during test categories 2 and 3 at 289 K (520R). The heat flow rate through the tank installed MLI at a tank/TPS spacing of 0.457 m was 1.204 watts with no MLI on the TPS and 0.059 watts through the customized MLI with three blankets on the TPS. Reducing the tank/TPS spacing from 0.457 m to 0.152 m the heat flow through the customized MLI increased by 10 percent.

  2. Thermal performance of multilayer insulations. [gas evacuation characteristics of three selected multilayer insulation composites

    NASA Technical Reports Server (NTRS)

    Keller, C. W.; Cunnington, G. R.; Glassford, A. P.

    1974-01-01

    Experimental and analytical studies were conducted in order to extend previous knowledge of the thermal performance and gas evacuation characteristics of three selected multilayer insulation (MLI) composites. Flat plate calorimeter heat flux measurements were obtained for 20- and 80- shield specimens using three representative layer densities over boundary temperatures ranging from 39 K (70 R) to 389 K (700 R). Laboratory gas evacuation tests were performed on representative specimens of each MLI composite after initially purging them with helium, nitrogen, or argon gases. In these tests, the specimens were maintained at temperatures between 128 K (230 R) and 300 K (540 R). Based on the results of the laboratory-scale tests, a composite MLI system consisting of 112 unperforated, double-aluminized Mylar reflective shields and 113 water preconditioned silk net spacer pairs was fabricated and installed on a 1.22-m-(4-ft-) diameter calorimeter tank.

  3. Thermal balance of a wall with PCM-enhanced thermal insulation

    SciTech Connect

    Kosny, Jan; Kossecka, Elizabeth; Williams, Teresa

    2010-01-01

    ABSTRACT: PCM insulation mixtures function as lightweight thermal mass components. It is expected that these types of dynamic insulation systems will contribute to the objective of reducing energy use in buildings. In this paper, dynamic thermal properties of a material in which phase hange occurs are analyzed, using the temperature-dependent specific heat model. Integral formula for the total heat flow in finite time interval, across the surface of a slab of the phase change material, was derived. Simulations have been performed to analyze heat transfer through a light-weight wall assembly with PCM-enhanced insulation, in different external climate thermal conditions. Results of simulations indicate that for cyclic processes, the effect of PCM in an insulation layer results rather in time shifting of the heat flux extreme values than in reduction of the total heat flow. The heat gains maxima, resulting in high cooling loads, are shifted in time by about two hours and reduced about 15% to 30% for not very high external sol-air temperatures.

  4. Synthesis and Properties of Cross-Linked Polyamide Aerogels

    NASA Technical Reports Server (NTRS)

    Williams, Jarrod C.; Meador, Mary Ann; McCorkle, Linda

    2015-01-01

    We report the first synthesis of cross-linked polyamide aerogels through step growth polymerization using a combination of diamines, diacid chloride and triacid chloride. Polyamide oligomers endcapped with amines are prepared as stable solutions in N-methylpyrrolidinone from several different diamine precursors and 1,3-benzenedicarbonyl dichloride. Addition of 1,3,5-benzenetricarbonyl trichloride yields gels which form in under five minutes according to the scheme shown. Solvent exchange of the gels into ethanol, followed by drying using supercritical CO2 extraction gives colorless aerogels with densities around 0.1 to 0.2 gcm3. Thicker monolithes of the polyamide aerogels are stiff and strong, while thin films of certain formulations are highly flexible, durable, and even translucent. These materials may have use as insulation for deployable space structures, rovers, habitats or extravehicular activity suits as well as in many terrestrial applications. Strucure property relationships of the aerogels, including surface area, mechanical properties, and thermal conductivity will be discussed.

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

    NASA Technical Reports Server (NTRS)

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

    1995-01-01

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

  6. Optothermal nonlinearity of silica aerogel

    NASA Astrophysics Data System (ADS)

    Braidotti, Maria Chiara; Gentilini, Silvia; Fleming, Adam; Samuels, Michiel C.; Di Falco, Andrea; Conti, Claudio

    2016-07-01

    We report on the characterization of silica aerogel thermal optical nonlinearity, obtained by z-scan technique. The results show that typical silica aerogels have nonlinear optical coefficient similar to that of glass (≃10-12 m2/W), with negligible optical nonlinear absorption. The nonlinear coefficient can be increased to values in the range of 10-10 m2/W by embedding an absorbing dye in the aerogel. This value is one order of magnitude higher than that observed in the pure dye and in typical highly nonlinear materials like liquid crystals.

  7. Standard specification for spray-applied rigid cellular polyurethane thermal insulation. ASTM standard

    SciTech Connect

    Not Available

    1996-11-01

    DoD adopted. This practice is under the jurisdiction of ASTM Committee C-16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.22 on Organic and Nonhomogeneous Inorganic Thermal Insulations. Current edition approved Sep. 10, 1996. Published November 1996. Originally published as C 1029-85. Last previous edition was C 1029-90.

  8. Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator.

    PubMed

    Lin, Weiwei; Chen, Kai; Zhang, Shufeng; Chien, C L

    2016-05-01

    We report a large enhancement of thermally injected spin current in normal metal (NM)/antiferromagnet (AF)/yttrium iron garnet (YIG), where a thin AF insulating layer of NiO or CoO can enhance the spin current from YIG to a NM by up to a factor of 10. The spin current enhancement in NM/AF/YIG, with a pronounced maximum near the Néel temperature of the thin AF layer, has been found to scale linearly with the spin-mixing conductance at the NM/YIG interface for NM=3d, 4d, and 5d metals. Calculations of spin current enhancement and spin mixing conductance are qualitatively consistent with the experimental results. PMID:27203336

  9. Additional Characterization of Min-K TE-1400 Thermal Insulation

    SciTech Connect

    Hemrick, James Gordon; King, James

    2011-01-01

    Min-K 1400TE (Thermal Ceramics, Augusta, Georgia) insulation material was further characterized at Oak Ridge National Laboratory (ORNL) for use in structural applications under gradient temperature conditions in an inert environment. Original characterization of Min-K was undertaken from April 1997 to July 2008 to determine its high temperature compressive strength and stress relaxation behavior up to 900 C in helium along with the formulation of a general model for the mechanical behavior exhibited by Min-K under these conditions. The additional testing described in this report was undertaken from April 2009 to June 2010 in an effort to further evaluate the mechanical behavior of Min-K when subjected to a variety of conditions including alternative test temperatures and time scales than previously measured. The behavior of Min-K under changing environments (temperature and strain), lateral loads, and additional isothermal temperatures was therefore explored.

  10. Enhancement of Thermally Injected Spin Current through an Antiferromagnetic Insulator

    NASA Astrophysics Data System (ADS)

    Lin, Weiwei; Chen, Kai; Zhang, Shufeng; Chien, C. L.

    2016-05-01

    We report a large enhancement of thermally injected spin current in normal metal (NM)/antiferromagnet (AF)/yttrium iron garnet (YIG), where a thin AF insulating layer of NiO or CoO can enhance the spin current from YIG to a NM by up to a factor of 10. The spin current enhancement in NM /AF /YIG , with a pronounced maximum near the Néel temperature of the thin AF layer, has been found to scale linearly with the spin-mixing conductance at the NM /YIG interface for NM =3 d , 4 d , and 5 d metals. Calculations of spin current enhancement and spin mixing conductance are qualitatively consistent with the experimental results.

  11. Design and Development of Aerogel-Based Antennas for Aerospace Applications: A Final Report to the NARI Seedling

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Miranda, Felix A.

    2014-01-01

    As highly porous solids possessing low density and low dielectric permittivity combined with good mechanical properties, polyimide (PI) aerogels offer great promise as an enabling technology for lightweight aircraft antenna systems. While they have been aggressively explored for thermal insulation, barely any effort has been made to leverage these materials for antennas or other applications that take advantage of their aforementioned attributes. In Phase I of the NARI Seedling Project, we fabricated PI aerogels with properties tailored to enable new antenna concepts with performance characteristics (wide bandwidth and high gain) and material properties (low density, environmental stability, and robustness) superior to the state of practice (SOP). We characterized electromagnetic properties, including permittivity, reflectivity, and propagation losses for the aerogels. Simple, prototype planar printed circuit patch antennas from down-selected aerogel formulations were fabricated by molding the aerogels to net shapes and by gold-metalizing the pattern onto the templates via electron beam evaporation in a clean room environment. These aerogel based antennas were benchmarked against current antenna SOP, and exhibited both broader bandwidth and comparable or higher gain performance at appreciably lower mass. Phase II focused on the success of the Phase I results pushing the PI aerogel based antenna technology further by exploring alternative antenna design (i.e., slot coupled antennas) and by examining other techniques for fabricating the antennas including ink jet printing with the goal of optimizing antenna performance and simplifying production. We also examined new aerogel formulations with better moisture and solvent resistance to survive processing conditions. In addition, we investigated more complex antenna designs including passive phased arrays such as 2x4 and 4x8 element arrays to assess the scalability of the aerogel antenna concept. Furthermore, we

  12. Ultralight nanofibre-assembled cellular aerogels with superelasticity and multifunctionality

    NASA Astrophysics Data System (ADS)

    Si, Yang; Yu, Jianyong; Tang, Xiaomin; Ge, Jianlong; Ding, Bin

    2014-12-01

    Three-dimensional nanofibrous aerogels (NFAs) that are both highly compressible and resilient would have broad technological implications for areas ranging from electrical devices and bioengineering to damping materials; however, creating such NFAs has proven extremely challenging. Here we report a novel strategy to create fibrous, isotropically bonded elastic reconstructed (FIBER) NFAs with a hierarchical cellular structure and superelasticity by combining electrospun nanofibres and the fibrous freeze-shaping technique. Our approach causes the intrinsically lamellar deposited electrospun nanofibres to assemble into elastic bulk aerogels with tunable densities and desirable shapes on a large scale. The resulting FIBER NFAs exhibit densities of >0.12 mg cm-3, rapid recovery from deformation, efficient energy absorption and multifunctionality in terms of the combination of thermal insulation, sound absorption, emulsion separation and elasticity-responsive electric conduction. The successful synthesis of such fascinating materials may provide new insights into the design and development of multifunctional NFAs for various applications.

  13. Ultralight nanofibre-assembled cellular aerogels with superelasticity and multifunctionality.

    PubMed

    Si, Yang; Yu, Jianyong; Tang, Xiaomin; Ge, Jianlong; Ding, Bin

    2014-01-01

    Three-dimensional nanofibrous aerogels (NFAs) that are both highly compressible and resilient would have broad technological implications for areas ranging from electrical devices and bioengineering to damping materials; however, creating such NFAs has proven extremely challenging. Here we report a novel strategy to create fibrous, isotropically bonded elastic reconstructed (FIBER) NFAs with a hierarchical cellular structure and superelasticity by combining electrospun nanofibres and the fibrous freeze-shaping technique. Our approach causes the intrinsically lamellar deposited electrospun nanofibres to assemble into elastic bulk aerogels with tunable densities and desirable shapes on a large scale. The resulting FIBER NFAs exhibit densities of >0.12 mg cm(-3), rapid recovery from deformation, efficient energy absorption and multifunctionality in terms of the combination of thermal insulation, sound absorption, emulsion separation and elasticity-responsive electric conduction. The successful synthesis of such fascinating materials may provide new insights into the design and development of multifunctional NFAs for various applications. PMID:25512095

  14. Hemp Thermal Insulation Concrete with Alternative Binders, Analysis of their Thermal and Mechanical Properties

    NASA Astrophysics Data System (ADS)

    Sinka, M.; Sahmenko, G.; Korjakins, A.; Radina, L.; Bajare, D.

    2015-11-01

    One of the main challenges that construction industry faces today is how to address the demands for more sustainable, environmentally friendly and carbon neutral construction materials and building upkeep processes. One of the answers to these demands is lime-hemp concrete (LHC) building materials - carbon negative materials that have sufficient thermal insulation capabilities to be used as thermal insulation materials for new as well as for existing buildings. But one problem needs to be overcome before these materials can be used on a large scale - current manufacturing technology allows these materials to be used only as self-bearing thermal insulation material with large labour intensity in the manufacturing process. In order to lower the labour intensity and allow the material to be used in wider applications, a LHC block and board production is necessary, which in turn calls for the binders different from the classically used ones, as they show insufficient mechanical strength for this new use. The particular study focuses on alternative binders produced using gypsum-cement compositions ensuring they are usable in outdoor applications together with hemp shives. Physical, mechanical, thermal and water absorption properties of hemp concrete with various binders are addressed in the current study.

  15. Aerogel commercialization pilot project. Final program report

    SciTech Connect

    1996-02-13

    Aerogels are extremely light weight, high surface area, very insulative materials that offer many potential improvements to commercial products. Aerogels have been the subject of extensive research at Department of Energy Laboratories and have been considered one of the technology most ready for commercialization. However, commercialization of the technology had been difficult for the National Laboratories since end users were not interested in the high temperature and high pressure chemical processes involved in manufacturing the raw material. Whereas, Aerojet as a supplier of rocket fuels, specialty chemicals and materials had the manufacturing facilities and experience to commercially produce aerogel-type products. Hence the TRP provided a link between the technology source (National Laboratories), the manufacturing (Aerojet) and the potential end users (other TRP partners). The program successfully produced approximately 500 ft{sup 2} of organic aerogel but failed to make significant quantities of silica aerogel. It is significant that this production represents both the largest volume and biggest pieces of organic aerogel ever produced. Aerogels, available from this program, when tested in several prototype commercial products were expected to improve the products performance, but higher than expected projected production costs for large scale manufacture of aerogels has limited continued commercial interest from these partners. Aerogels do, however, offer potential as a specialty material for some high value technology and defense products.

  16. Synthesis and Characterization of Poly(maleic Anhydride)s Cross-linked Polyimide Aerogels

    NASA Technical Reports Server (NTRS)

    Guo, Haiquan; Meador, Mary Ann B.

    2015-01-01

    With the development of technology for aerospace applications, new thermal insulation materials are required to be flexible and capable of surviving high heat flux. For instance, flexible insulation is needed for inflatable aerodynamic decelerators which are used to slow spacecraft for entry, descent and landing (EDL) operations. Polyimide aerogels have low density, high porosity, high surface area, and better mechanical properties than silica aerogels and can be made into flexible thin films, thus they are potential candidates for aerospace needs. The previously reported cross-linkers such as octa(aminophenyl)silsesquioxane (OAPS) and 1,3,5-triaminophenoxybenzene (TAB) are either expensive or not commercially available. Here, we report the synthesis of a series of polyimide aerogels cross-linked using various commercially available poly(maleic anhydride)s, as seen in Figure 1. The amine end capped polyimide oligomers were made with 3,3,4,4-biphenyltetracarboxylic dianhydride (BPDA) and diamine combinations of dimethylbenzidine (DMBZ) and 4, 4-oxydianiline (ODA). The resulting aerogels have low density (0.12 gcm3 to 0.16 gcm3), high porosity (90) and high surface area (380-554 m2g). The effect of the different poly(maleic anhydride) cross-linkers and polyimide backbone structures on density, shrinkage, porosity, surface area, mechanical properties, moisture resistance and thermal properties will be discussed.

  17. Insulation Performance of Heat-Resistant Material for High-Speed Aircraft Under Thermal Environments

    NASA Astrophysics Data System (ADS)

    Wu, Dafang; Wang, Yuewu; Gao, Zhentong; Yang, Jialing

    2015-09-01

    Lightweight insulation materials are widely used to thermally protect high-speed aircraft, such as missiles. Thermal conductivity is an important parameter used to evaluate the efficiency of a material's thermal insulation performance. Since thermal conductivities provided from material handbooks or manufacturers are discrete data for different temperature ranges, there is a deviation between those and actual parameters in terms of continuous nonlinear variations. Therefore, this study measures the thermal conductivities of lightweight thermal insulation materials at high temperatures, and the relationship between the thermal conductivity and temperature is obtained. A finite element model of the thermal insulation materials is also established and applied to numerically calculate the thermal insulation properties for high-temperature ceramic fiber insulation materials using the experimentally obtained nonlinear relationship between thermal conductivity and temperature. Additionally, a transient aerodynamic heating experiment simulation system is used to thermally test the same materials; the calculated and experimental results for the same materials are compared, which exhibit good consistency that demonstrates that accurate results can be obtained from the numerical computation using the relationship established from the experimentally measured conductivity and temperature.

  18. Critical Review of Industrial Techniques for Thermal-Conductivity Measurements of Thermal Insulation Materials

    NASA Astrophysics Data System (ADS)

    Hammerschmidt, Ulf; Hameury, Jacques; Strnad, Radek; Turzó-Andras, Emese; Wu, Jiyu

    2015-07-01

    This paper presents a critical review of current industrial techniques and instruments to measure the thermal conductivity of thermal insulation materials, especially those insulations that can operate at temperatures above and up to . These materials generally are of a porous nature. The measuring instruments dealt with here are selected based on their maximum working temperature that should be higher than at least . These instruments are special types of the guarded hot-plate apparatus, the guarded heat-flow meter, the transient hot-wire and hot-plane instruments as well as the laser/xenon flash devices. All technical characteristics listed are quoted from the generally accessible information of the relevant manufacturers. The paper includes rankings of the instruments according to their standard retail price, the maximum sample size, and maximum working temperature, as well as the minimum in their measurement range.

  19. Method and apparatus for filling thermal insulating systems

    DOEpatents

    Arasteh, Dariush K.

    1992-01-01

    A method for filling insulated glazing units is disclosed. The method utilizes a vacuum chamber in which the insulated glazing units are placed. The insulated glazing units and vacuum chamber are evacuated simultaneously. The units are then refilled with a low conductance gas such as Krypton while the chamber is simultaneously refilled with air.

  20. Method and apparatus for filling thermal insulating systems

    DOEpatents

    Arasteh, D.K.

    1992-01-14

    A method for filling insulated glazing units is disclosed. The method utilizes a vacuum chamber in which the insulated glazing units are placed. The insulated glazing units and vacuum chamber are evacuated simultaneously. The units are then refilled with a low conductance gas such as Krypton while the chamber is simultaneously refilled with air. 3 figs.

  1. Structural analysis of a thermal insulation retainer assembly

    NASA Technical Reports Server (NTRS)

    Greene, William H.; Gray, Carl E., Jr.

    1989-01-01

    In January 1989 an accident occurred in the National Transonic Facility wind tunnel at NASA Langley Research Center that was believed to be caused by the failure of a thermal insulation retainer. A structural analysis of this retainer assembly was performed in order to understand the possible failure mechanisms. Two loading conditions are important and were considered in the analysis. The first is the centrifugal force due to the fact that this retainer is located on the fan drive shaft. The second loading is a differential temperature between the retainer assembly and the underlying shaft. Geometrically nonlinear analysis is required to predict the stiffness of this component and to account for varying contact regions between various components in the assembly. High, local stresses develop in the band part of the assembly near discontinuities under both the centrifugal and thermal loadings. The presence of an aluminum ring during a portion of the part's operating life was found to increase the stresses in other regions of the band. Under the centrifugal load, high bending stresses develop near the intersection of the band with joints in the assembly. These high bending stresses are believed to be the most likely cause for failure of the assembly.

  2. Temperature distribution in a layer of an active thermal insulation system heated by a gas burner

    SciTech Connect

    Maruyama, Shigenao . Inst. of Fluid Science); Shimizu, Naotaka . Dept. of Mechanical Engineering)

    1993-12-01

    The temperature distribution in a layer of an active thermal insulation system was measured. A semitransparent porous layer was heated by a gas burner, and air was injected from the back face of the layer. The temperature in the layer was measured by thermocouples. The temperature distributions were compared with numerical solutions. The thermal penetration depth of the active thermal insulation layer with gas injection can be reduced to 3 mm. When the surface temperature of a conventional insulation layer without gas injection reached 1,500 K, the temperature at the back surface of a 10-mm-thick layer reached 600 K. The transient temperature of the active thermal insulation reached a steady state very quickly compared with that of the conventional insulation. These characteristics agreed qualitatively with the numerical solutions.

  3. Investigation of potential waste material insulating properties at different temperature for thermal storage application

    NASA Astrophysics Data System (ADS)

    Ali, T. Z. S.; Rosli, A. B.; Gan, L. M.; Billy, A. S.; Farid, Z.

    2013-12-01

    Thermal energy storage system (TES) is developed to extend the operation of power generation. TES system is a key component in a solar energy power generation plant, but the main issue in designing the TES system is its thermal capacity of storage materials, e.g. insulator. This study is focusing on the potential waste material acts as an insulator for thermal energy storage applications. As the insulator is used to absorb heat, it is needed to find suitable material for energy conversion and at the same time reduce the waste generation. Thus, a small-scale experimental testing of natural cooling process of an insulated tank within a confined room is conducted. The experiment is repeated by changing the insulator from the potential waste material and also by changing the heat transfer fluid (HTF). The analysis presented the relationship between heat loss and the reserved period by the insulator. The results show the percentage of period of the insulated tank withstands compared to tank insulated by foam, e.g. newspaper reserved the period of 84.6% as much as foam insulated tank to withstand the heat transfer of cooking oil to the surrounding. The paper finally justifies the most potential waste material as an insulator for different temperature range of heat transfer fluid.

  4. Thermal insulation of young calves exposed to cold.

    PubMed Central

    Rawson, R E; Dziuk, H E; Good, A L; Anderson, J F; Bates, D W; Ruth, G R

    1989-01-01

    Tissue, external and whole animal insulation values were determined for 12 newborn male Holstein calves continuously housed for two weeks in hutches within environmental chambers in which temperature was maintained at a constant 17 degrees C (three calves) or cycled on a daily basis either between -20 degrees and -8 degrees C (three calves) or between -30 degrees and -18 degrees C (six calves). Three of the six calves at the coldest temperature were outfitted with an insulated coat. The insulated coat provided calves a 52% increase in total insulation. Tissue insulation of cold-housed calves increased 37.2% over the first two weeks of life. It was concluded that the capacity for vasoconstriction improved with age. External insulation did not change significantly except during the first week in cold-housed calves without insulated coats. External insulation values were five to eight times those of tissue insulation values for all treatment groups. This indicated that insulation of structures external to the skin (hair, bedding, ground, etc.) provided most of the insulation for calves. PMID:2766147

  5. Thermal response of rigid and flexible insulations and reflective coating in an aeroconvective heating environment

    NASA Technical Reports Server (NTRS)

    Kourtides, D. A.; Chiu, S. A.; Iverson, D. J.; Lowe, D. M.

    1992-01-01

    Described here is the thermal performance of rigid and flexible thermal protection systems considered for potential use in future Aeroassist Space Transfer Vehicles. The thermal response of these materials subjected to aeroconvective heating from a plasma arc is described. Properties that were measured included the thermal conductivity of both rigid and flexible insulations at various temperatures and pressures and the emissivity of the fabrics used in the flexible insulations. The results from computerized thermal analysis models describing the thermal response of these materials subjected to flight conditions are included.

  6. Clothing resultant thermal insulation determined on a movable thermal manikin. Part II: effects of wind and body movement on local insulation.

    PubMed

    Lu, Yehu; Wang, Faming; Wan, Xianfu; Song, Guowen; Zhang, Chengjiao; Shi, Wen

    2015-10-01

    Part II of this two-part series study was focused on examining the effects of wind and body movement on local clothing thermal insulation. Seventeen clothing ensembles with different layers (i.e., 1, 2, or 3 layers) were selected for this study. Local thermal insulation with different air velocities (0.15, 1.55, and 4.0 m/s) and walking speeds (0, 0.75, and 1.17 m/s) were investigated on a thermal manikin. Empirical equations for estimating local resultant clothing insulation as a function of local insulation, air velocity, and walking speed were developed. The results showed that the effects of wind and body movement on local resultant thermal resistance are complex and differ distinctively among different body parts. In general, the reductions of local insulation with wind at the chest, abdomen, and pelvis were greater than those at the lower leg and back, and the changes at the body extremity such as the forearm, thigh, and lower leg were higher than such immobile body parts as the chest and back. In addition, the wind effect interacted with the walking effect. This study may have important applications in human local thermal comfort modeling and functional clothing design. PMID:25605409

  7. Clothing resultant thermal insulation determined on a movable thermal manikin. Part II: effects of wind and body movement on local insulation

    NASA Astrophysics Data System (ADS)

    Lu, Yehu; Wang, Faming; Wan, Xianfu; Song, Guowen; Zhang, Chengjiao; Shi, Wen

    2015-10-01

    Part II of this two-part series study was focused on examining the effects of wind and body movement on local clothing thermal insulation. Seventeen clothing ensembles with different layers (i.e., 1, 2, or 3 layers) were selected for this study. Local thermal insulation with different air velocities (0.15, 1.55, and 4.0 m/s) and walking speeds (0, 0.75, and 1.17 m/s) were investigated on a thermal manikin. Empirical equations for estimating local resultant clothing insulation as a function of local insulation, air velocity, and walking speed were developed. The results showed that the effects of wind and body movement on local resultant thermal resistance are complex and differ distinctively among different body parts. In general, the reductions of local insulation with wind at the chest, abdomen, and pelvis were greater than those at the lower leg and back, and the changes at the body extremity such as the forearm, thigh, and lower leg were higher than such immobile body parts as the chest and back. In addition, the wind effect interacted with the walking effect. This study may have important applications in human local thermal comfort modeling and functional clothing design.

  8. Thermal performance of multilayer insulation. I - Derivation of a prediction-based heat-flux equation

    NASA Astrophysics Data System (ADS)

    Amano, Toshiyuki

    1993-07-01

    A prediction-based equation for heat flux through a multilayer insulator was derived from comparison of experimental results between room temperature and liquid nitrogen temperature. The employed multilayer insulator was a laminated material with a polyester net inserted between aluminized Mylar films. The prediction equation consists of one thermal radiation and two thermal conduction terms. The first conduction term is that of ordinary thermal contact conductance. The second conduction term depends on the self-compression of the multilayer insulation. The predicted values resulting from the obtained equation coincided fairly well with measured values.

  9. Thermal Performance of a Customized Multilayer Insulation (MLI). Design and Fabrication of Test Facility Hardware

    NASA Technical Reports Server (NTRS)

    Leonhard, K. E.

    1975-01-01

    The design, fabrication, and assembly of hardware for testing the performance of a customized multilayer insulation are discussed. System components described include the thermal payload simulator, the modified cryoshroud, and a tank back pressure control device designed to maintain a constant liquid boiling point during the thermal evaluation of the multilayer insulation. The thermal payload simulator will provide a constant temperature surface in the range of 20.5 to 417K (37 to 750R) for the insulated tank to view. The cryoshroud was modified to establish a low temperature black body cavity while limiting liquid hydrogen usage to a minimum feasible rate.

  10. Thermal, Morphological and Rheological Properties of Rigid Polyurethane Foams as Thermal Insulating Materials

    SciTech Connect

    Kim, Ji Mun; Han, Mi Sun; Kim, Youn Hee; Kim, Woo Nyon

    2008-07-07

    The polyurethane foams (PUFs) were prepared by polyether polyols, polymeric 4,4'-diphenylmethane diisocyanate (PMDI), silicone surfactants, amine catalysts and cyclopentane as a blowing agent. Solid and liquid type fillers were used as a nucleating agent to decrease a cell size of the PUFs as well as improve the thermal insulating properties of the PUFs. The PUFs were prepared by adding solid and liquid type fillers in the range of 1 to 3 wt%. For the liquid type fillers, the cell size of the PUFs showed minimum and found to decrease compared the PUF without adding fillers. Also, thermal conductivity of the PUFs with adding fillers showed minimum. For the solid type fillers, cell size and thermal conductivity of the PUFs were observed to decrease with the filler content up to 3 wt%. From these results, it is suggested that the thermal insulating property of the PUFs can be improved by adding fillers as a nucleating agent. Also, storage and loss modulus of the PUFs will be presented to study gelling points of the PUFs.

  11. Water retention curves and thermal insulating properties of Thermosand

    NASA Astrophysics Data System (ADS)

    Leibniz, Otto; Winkler, Gerfried; Birk, Steffen

    2010-05-01

    The heat loss and the efficiency of isolating material surrounding heat supply pipes are essential issues for the energy budget of heat supply pipe lines. Until now heat loss from the pipe is minimized by enlarging the polyurethane (PU) - insulation thickness around the pipe. As a new approach to minimize the heat loss a thermally insulating bedding material was developed and investigated. Conventional bedding sands cover all necessary soil mechanical properties, but have a high thermal conductivity from λ =1,5 to 1,7 W/(m K). A newly developed embedding material 'Thermosand' shows thermal properties from λ=0,18 W/(m K) (dry) up to 0,88 W/(m K) (wet). The raw material originates from the waste rock stockpiles of a coal mine near Fohnsdorf, Austria. With high temperatures up to nearly 1000 ° C and a special mineral mixture, a natural burned reddish material resembling clinker arises. The soilmechanical properties of Thermosand has been thoroughly investigated with laboratory testing and in situ investigations to determine compaction-, permeability- and shear-behaviour, stiffness and corresponding physical parameters. Test trenches along operational heat pipes with temperature-measurement along several cross-sections were constructed to compare conventional embedding materials with 'Thermosand'. To investigate the influence of varying moisture content on thermal conductivity a 1:1 large scale model test in the laboratory to simulate real insitu-conditions was established. Based on this model it is planned to develop numerical simulations concerning varying moisture contents and unsaturated soil mechanics with heat propagation, including the drying out of the soil during heat input. These simulations require the knowledge about the water retention properties of the material. Thus, water retention curves were measured using both steady-state tension and pressure techniques and the simplified evaporation method. The steady-state method employs a tension table (sand

  12. Metabolic rate and thermal insulation in albino and hairless mice

    PubMed Central

    Mount, L. E.

    1971-01-01

    1. Rates of oxygen consumption of albino and hairless mice were measured in a metabolism chamber during periods of approximately 5 or 24 hr. Rectal temperature was measured before and after each period. The chamber temperatures used were 22, 30 and 32° C for both albino and hairless, and in addition 34 and 36° C for the hairless mice. 2. The mean age and body weight of the albino mice were 102 days and 34·6 g; the corresponding values for the hairless mice were 87 days and 32·8 g. 3. The mean minimum rates of oxygen consumption (ml./kg.min) were 31·0 for the albino and 38·8 for the hairless mouse; the corresponding estimated critical temperatures were in the ranges 30-32° C for the albino mouse and 32-34° C for the hairless mouse. 4. The mean values for core-ambient thermal insulation (° C.m2.hr/kcal) were 0·418 and 0·328 for the albino mouse, and 0·275 and 0·221 for the hairless mouse, at 22 and 30° C respectively in each case. PMID:5097602

  13. Bionics in textiles: flexible and translucent thermal insulations for solar thermal applications.

    PubMed

    Stegmaier, Thomas; Linke, Michael; Planck, Heinrich

    2009-05-13

    Solar thermal collectors used at present consist of rigid and heavy materials, which are the reasons for their immobility. Based on the solar function of polar bear fur and skin, new collector systems are in development, which are flexible and mobile. The developed transparent heat insulation material consists of a spacer textile based on translucent polymer fibres coated with transparent silicone rubber. For incident light of the visible spectrum the system is translucent, but impermeable for ultraviolet radiation. Owing to its structure it shows a reduced heat loss by convection. Heat loss by the emission of long-wave radiation can be prevented by a suitable low-emission coating. Suitable treatment of the silicone surface protects it against soiling. In combination with further insulation materials and flow systems, complete flexible solar collector systems are in development. PMID:19376769

  14. High-Temperature Properties of Ceramic Fibers and Insulations for Thermal Protection of Atmospheric Entry and Hypersonic Cruise Vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

    1988-01-01

    Multilayer insulations which will operate in the 500C to 1000C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described in this paper consist of ceramic fabrics, insulations, and metal foils quilted together using ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics of these insulations must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of multilayer insulations and are compared to the baseline Advanced Flexible Reusable Surface Insulation

  15. Flexible nanofiber-reinforced aerogel (xerogel) synthesis, manufacture, and characterization.

    PubMed

    Li, Lichun; Yalcin, Baris; Nguyen, Baochau N; Meador, Mary Ann B; Cakmak, Miko

    2009-11-01

    Silica aerogels are sol-gel-derived materials consisting of interconnected nanoparticle building blocks that form an open and highly porous three-dimensional silica network. Flexible aerogel films could have wide applications in various thermal insulation systems. However, aerogel thin films produced with a pure sol-gel process have inherent disadvantages, such as high fragility and moisture sensitivity, that hinder wider applications of these materials. We have developed synthesis and manufacturing methods to incorporate electrospun polyurethane nanofibers into the cast sol film prior to gelation of the silica-based gel in order to reinforce the structure and overcome disadvantages such as high fragility and poor mechanical strength. In this method, a two-stage sol-gel process was employed: (1) acid-catalyzed tetraethyl orthosilicate hydrolysis and (2) base-catalyzed gelation. By precisely controlling the sol gelation kinetics with the amount of base present in the formulation, nanofibers were electrospun into the sol before the onset of the gelation process and uniformly embedded in the silica network. Nanofiber reinforcement did not alter the thermal conductivity and rendered the final composite film bendable and flexible. PMID:20356119

  16. Standard specification for fibrous glass duct lining insulation (thermal and sound absorbing material). ASTM standard

    SciTech Connect

    1998-06-01

    This specification is under the jurisdiction of ASTM Committee C-16 on Thermal Insulation and is the direct responsibility of Subcommittee C16.23 on Blanket and Loose Fill Insulation. Current edition approved Jan. 10, 1998 and published June 1998. It was originally published as C 1071-86. The last previous edition was C 1071-91.

  17. 24 CFR 3280.207 - Requirements for foam plastic thermal insulating materials.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... SAFETY STANDARDS Fire Safety § 3280.207 Requirements for foam plastic thermal insulating materials. (a... Technology Research Institute (IIT) Report, “Development of Mobile Home Fire Test Methods to Judge the Fire-Safe Performance of Foam Plastic Sheathing and Cavity Insulation, IITRI Fire and Safety...

  18. 24 CFR 3280.207 - Requirements for foam plastic thermal insulating materials.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Product Safety Commission requirements in 16 CFR parts 1209 and 1404. (2) Other loose-fill insulation that... SAFETY STANDARDS Fire Safety § 3280.207 Requirements for foam plastic thermal insulating materials. Link... Technology Research Institute (IIT) Report, “Development of Mobile Home Fire Test Methods to Judge the...

  19. 24 CFR 3280.207 - Requirements for foam plastic thermal insulating materials.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... SAFETY STANDARDS Fire Safety § 3280.207 Requirements for foam plastic thermal insulating materials. (a... Technology Research Institute (IIT) Report, “Development of Mobile Home Fire Test Methods to Judge the Fire-Safe Performance of Foam Plastic Sheathing and Cavity Insulation, IITRI Fire and Safety...

  20. 24 CFR 3280.207 - Requirements for foam plastic thermal insulating materials.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... SAFETY STANDARDS Fire Safety § 3280.207 Requirements for foam plastic thermal insulating materials. (a... Technology Research Institute (IIT) Report, “Development of Mobile Home Fire Test Methods to Judge the Fire-Safe Performance of Foam Plastic Sheathing and Cavity Insulation, IITRI Fire and Safety...

  1. 24 CFR 3280.207 - Requirements for foam plastic thermal insulating materials.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... SAFETY STANDARDS Fire Safety § 3280.207 Requirements for foam plastic thermal insulating materials. (a... Technology Research Institute (IIT) Report, “Development of Mobile Home Fire Test Methods to Judge the Fire-Safe Performance of Foam Plastic Sheathing and Cavity Insulation, IITRI Fire and Safety...

  2. Insulation.

    ERIC Educational Resources Information Center

    Rhea, Dennis

    This instructional unit is one of 10 developed by students on various energy-related areas that deals specifically with insulation. Its objective is for the student to be able to determine insulation needs of new or existing structures, select type to use, use installation techniques, calculate costs, and apply safety factors. Some topics covered…

  3. Improvement of thermal conductivity of nano MgO/epoxy composites for electrical insulation materials

    NASA Astrophysics Data System (ADS)

    Majeed, Kawakib Jassim

    2013-12-01

    In the present study the dielectric and thermal properties of nano and micro MgO / Epoxy composites were studied with different weight percentage ratios, aiming at the development of electrical insulating materials with high thermal conductivity, this can be achieved by adding a low concentration of thermally conducting but electrically insulating nanofillers such as MgO nanoparticles, the results are discussed by determining the relative permittivity, tan delta and the thermal conductivity of the tested specimens. The obtained results showed improvement in the thermal conductivity values without deteriorating the dielectric properties.

  4. The design of a die with a vacuum thermal insulation

    NASA Astrophysics Data System (ADS)

    Baginski, A. G.; Utyev, O. M.; Kondratyeva, Y. M.

    2016-04-01

    A new design of a die for the polymer underwater granulation plants has been developed. It differs from similar plants in the design of heat-insulating elements. Vacuum hollows are used as a heat insulator. A vacuumization process does not require a separate operation, and it is conducted simultaneously with connection of all the elements of the die by a brazing method.

  5. Flammability, odor, offgassing, thermal vacuum stability, and compatibility with aerospace fluids of wire insulations

    NASA Technical Reports Server (NTRS)

    Hirsch, David; Johnson, Harry

    1994-01-01

    The NASA Lewis Research Center requested NASA Johnson Space Center White Sands Test Facility to conduct flammability, odor, offgassing, thermal vacuum stability, and compatibility tests with aerospace fluids of several wire insulations.

  6. Polyolefin-based aerogels

    NASA Technical Reports Server (NTRS)

    Lee, Je Kyun (Inventor); Gould, Gerogle L. (Inventor)

    2010-01-01

    The present invention relates to cross-linked polyolefin aerogels in simple and fiber-reinforced composite form. Of particular interest are polybutadiene aerogels. Especially aerogels derived from polybutadienes functionalized with anhydrides, amines, hydroxyls, thiols, epoxies, isocyanates or combinations thereof.

  7. Reusable Surface Insulation Tile Thermal Protection Materials: Past, Present and the Future

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Stewart, David A.; Venkatapathy, Ethiras (Technical Monitor)

    2002-01-01

    Silica (LI-900) Reusable Surface Insulation (RSI) tile have been used on the majority of the Shuttle since its initial flight. Its overall performance with Reaction Cured Glass (RCG) coating applied will be reviewed. Improvements in insulations, Fibrous Refractory Composite Insulation (FRCI-12) and Alumina Enhanced Thermal Barrier (AETB-8) and coatings/surface treatments such as Toughened Uni-Piece Fibrous Insulation (TUFI) have been developed and successfully applied. The performance of these enhancements on the Shuttle Orbiters over the past few years along with the next version of tile materials, High Efficiency Tantalum-based Ceramic (HETC) with even broader applicability will also be discussed.

  8. Effect of Temperature and Density Variations on Thermal Conductivity of Polystyrene Insulation Materials in Oman Climate

    NASA Astrophysics Data System (ADS)

    Khoukhi, M.; Tahat, M.

    2015-07-01

    The thermal and energy performance of buildings depends on the thermal characteristics of the building envelope and particularly on the thermal resistance of the insulation material used. The ability of a thermal insulation material to transmit heat in the presence of a temperature gradient is determined by its thermal conductivity. The thermal conductivity values of building insulation materials are generally given at 24°C according to ASTM standards. Actually, such a material when used in a building envelope is exposed to significant and continuous temperature changes, essentially due to the changes in outdoor temperature and solar radiation, especially in harsh climate. The main objective of this study is to investigate the relationship between the temperature and the thermal conductivity of polystyrene, which is widely employed as a building insulation material in Oman, at various densities, using the developed experimental setup based on the guarded hot plate method. The results show that higher temperatures lead to higher thermal conductivities and the lower is the material density, the higher is the thermal conductivity. The envelope-induced cooling load for a simple building is also calculated, and it is shown that a lesser cooling load is needed for a high-density insulation.

  9. Thermal degradation of multilayer insulation due to the presence of penetrations

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Kelly, A. O.; Fesmire, J. E.

    2014-01-01

    Invented in the 1950s, cryogenic multilayer insulation (MLI) continues to be studied, tested, and analyzed as it represents a complex system that is integral with the total system to be insulated. Numerous tank and calorimeter tests have been performed using many different insulation approaches. Many different variables have been tested and documented, mainly within the insulation system itself. There are several factors in insulation application that can drive up the heat load on the entire system. These include the treatment of insulation seams, instrumentation wires running through the insulation, and the integration of the insulation with the structures and fluids. Several attempts have been made to identify the performance losses due to structural integration with a real system. Due to the nature of MLI, these were tied to specific programs and configuration dependent. In an effort to understand the complex heat transfer mechanisms surrounding such systems, a series of calorimeter testing coupled with thermal modeling of the calorimeter tests was put into place. Testing showed that a buffer of micro-fiberglass material such as Cryolite is a robust method of closing out MLI penetrations. Additionally, a validated thermal model was used to develop parametric analysis far beyond the limitations of the calorimeter testing. This paper presents the methodology and approach, with experimental data providing the basis for developing the thermal model and its results for applicability to future design cases.

  10. Mechanical and Thermal Characteristics of Insulation Materials for the KSTAR Magnet System at Cryogenic Temperature

    NASA Astrophysics Data System (ADS)

    Chung, Wooho; Lim, Bungsu; Kim, Myungkyu; Park, Hyunki; Kim, Keeman; Chu, Yong; Lee, Sangil

    2004-06-01

    The KSTAR(Korea Superconducting Tokamak Advanced Research) superconducting magnet is electrically insulated by the composite material of epoxy resin and glass fiber (2.5 kV/mm) and Kapton (8 kV/mm). The insulation composite material of epoxy resin and glass fiber is prepared using a VPI (Vacuum Pressure Impregnation) process. The superconducting magnet is under mechanical stress caused by the large temperature difference between the operation temperature of the magnet and room temperature. The large electro-magnetic force during the operation of the magnet is also exerted on the magnet. Therefore, the characteristics of the insulation material at cryogenic temperatures are very important and the tensile stress and thermal expansion coefficient for the insulation materials of the KSTAR superconducting magnet are measured. This paper presents results on mechanical properties of the insulation material for KSTAR magnets, such as density, ultimate tensile stress and thermal contraction between room temperature and cryogenic temperatures.

  11. Thermal Analysis and Design of Multi-layer Insulation for Re-entry Aerodynamic Heating

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran

    2001-01-01

    The combined radiation/conduction heat transfer in high-temperature multi-layer insulations was modeled using a finite volume numerical model. The numerical model was validated by comparison with steady-state effective thermal conductivity measurements, and by transient thermal tests simulating re-entry aerodynamic heating conditions. A design of experiments technique was used to investigate optimum design of multi-layer insulations for re-entry aerodynamic heating. It was found that use of 2 mm foil spacing and locating the foils near the hot boundary with the top foil 2 mm away from the hot boundary resulted in the most effective insulation design. A 76.2 mm thick multi-layer insulation using 1, 4, or 16 foils resulted in 2.9, 7.2, or 22.2 percent mass per unit area savings compared to a fibrous insulation sample at the same thickness, respectively.

  12. Solid phase microextraction device using aerogel

    DOEpatents

    Miller, Fred S.; Andresen, Brian D.

    2005-06-14

    A sample collection substrate of aerogel and/or xerogel materials bound to a support structure is used as a solid phase microextraction (SPME) device. The xerogels and aerogels may be organic or inorganic and doped with metals or other compounds to target specific chemical analytes. The support structure is typically formed of a glass fiber or a metal wire (stainless steel or kovar). The devices are made by applying gel solution to the support structures and drying the solution to form aerogel or xerogel. Aerogel particles may be attached to the wet layer before drying to increase sample collection surface area. These devices are robust, stable in fields of high radiation, and highly effective at collecting gas and liquid samples while maintaining superior mechanical and thermal stability during routine use. Aerogel SPME devices are advantageous for use in GC/MS analyses due to their lack of interfering background and tolerance of GC thermal cycling.

  13. Aerogel sorbents

    DOEpatents

    Begag, Redouane; Rhine, Wendell E; Dong, Wenting

    2016-04-05

    The current invention describes methods and compositions of various sorbents based on aerogels of various silanes and their use as sorbent for carbon dioxide. Methods further provide for optimizing the compositions to increase the stability of the sorbents for prolonged use as carbon dioxide capture matrices.

  14. Characterization of an Integral Thermal Protection and Cryogenic Insulation Material for Advanced Space Transportation Vehicles

    NASA Technical Reports Server (NTRS)

    Salerno, L. J.; White, S. M.; Helvensteijn, B. P. M.

    2000-01-01

    NASA's planned advanced space transportation vehicles will benefit from the use of integral/conformal cryogenic propellant tanks which will reduce the launch weight and lower the earth-to-orbit costs considerably. To implement the novel concept of integral/conformal tanks requires developing an equally novel concept in thermal protection materials. Providing insulation against reentry heating and preserving propellant mass can no longer be considered separate problems to be handled by separate materials. A new family of materials, Superthermal Insulation (STI), has been conceiving and investigated by NASA's Ames Research Center to simultaneously provide both thermal protection and cryogenic insulation in a single, integral material.

  15. Effective Thermal Conductivity of High Temperature Insulations for Reusable Launch Vehicles

    NASA Technical Reports Server (NTRS)

    Daryabeigi, Kamran

    1999-01-01

    An experimental apparatus was designed to measure the effective thermal conductivity of various high temperature insulations subject to large temperature gradients representative of typical launch vehicle re-entry aerodynamic heating conditions. The insulation sample cold side was maintained around room temperature, while the hot side was heated to temperatures as high as 1800 degrees Fahrenheit. The environmental pressure was varied from 0.0001 to 760 torr. All the measurements were performed in a dry gaseous nitrogen environment. The effective thermal conductivity of Saffil, Q-Fiber felt, Cerachrome, and three multi-layer insulation configurations were measured.

  16. Development of New Generation of Thermally-Enhanced Fiber Glass Insulation

    SciTech Connect

    Kosny, Jan; Yarbrough, David W; Childs, Phillip W; Miller, William A; Atchley, Jerald Allen; Shrestha, Som S

    2010-03-01

    This report presents experimental and numerical results from thermal performance studies. The purpose of this Cooperative Research and Development Agreement (CRADA) between UT-Battelle, LLC and John s Manville was to design a basic concept of a new generation of thermally-enhanced fiber glass insulation. Different types of Phase Change Materials (PCMs) have been tested as dynamic components in buildings during the last 4 decades. Most historical studies have found that PCMs enhance building energy performance. Some PCM-enhanced building materials, like PCM-gypsum boards or PCM-impregnated concretes have already found their limited applications in different countries. Today, continued improvements in building envelope technologies suggest that throughout Southern and Central U.S. climates, residences may soon be routinely constructed with PCM in order to maximize insulation effectiveness and maintain low heating and cooling loads. The proposed thermally-enhanced fiber glass insulation will maximize this integration by utilizing a highly-efficient building envelope with high-R thermal insulation, active thermal mass and superior air-tightness. Improved thermal resistance will come from modifications in infrared internal characteristics of the fiber glass insulation. Thermal mass effect can be provided by proprietary thermally-active microencapsulated phase change material (PCM). Work carried out at the Oak Ridge National Laboratory (ORNL) on the CRADA is described in this report.

  17. Under-deck roof insulation upgrades plant's thermal efficiency

    SciTech Connect

    Not Available

    1984-09-01

    By retrofitting an old building with customized fiberglass insulation, a tractor trailer manufacturing plant has cut its annual fuel costs by $60,000. In this case study, the efficiency of the insulation system meant that the heating requirements of the building could be met with a smaller, more economical heating system. This reduced capital expenditure is a savings that is often overlooked when a project is being planned. Besides reduction in energy costs, the insulation dampened the noise levels of the building and the white ceiling and walls improved lightreflection.

  18. Thermal highly porous insulation materials made of mineral raw materials

    NASA Astrophysics Data System (ADS)

    Mestnikov, A.

    2015-01-01

    The main objective of the study is to create insulating foam based on modified mineral binders with rapid hardening. The results of experimental studies of the composition and properties of insulating foam on the basis of rapidly hardening Portland cement (PC) and gypsum binder composite are presented in the article. The article proposes technological methods of production of insulating foamed concrete and its placement to the permanent shuttering wall enclosures in monolithic-frame construction and individual energy-efficient residential buildings, thus reducing foam shrinkage and improving crack-resistance.

  19. Composite ceria-coated aerogels and methods of making the same

    DOEpatents

    Eyring, Edward M; Ernst, Richard D; Turpin, Gregory C; Dunn, Brian C

    2013-05-07

    Ceria-coated aerogels can include an aerogel support material having a stabilized ceria coating thereon. The ceria coating can be formed by solution or vapor deposition of alcogels or aerogels. Additional catalytic metal species can also be incorporated into the coating to form multi-metallic compounds having improved catalytic activity. Further, the ceria coated aerogels retain high surface areas at elevated temperatures. Thus, improvements in catalytic activity and thermal stability can be achieved using these ceria-coated composite aerogels.

  20. Nano-casted Metal Oxide Aerogels as Dual Purpose Structural Components for Space Exploration

    NASA Technical Reports Server (NTRS)

    Vassilaras, Plousia E.

    2004-01-01

    NASA missions and space exploration rely on strong, ultra lightweight materials. Such materials are needed for building up past and present space vehicles such as the Sojourner Rover (1997) or the two MERs (2003), but also for a number of components and/or systems including thermal insulators, Solar Sails, Rigid Aeroshells, and Ballutes. The purpose of my internship here at Glenn Research Center is to make dual purpose materials; materials that in addition to being lightweight have electronic, photophysical and magnetic properties and, therefore, act as electronic components and sensors as well as structural components. One type of ultra lightweight material of great interest is aerogels, which have densities ranging from 0.003 g/cc to 0.8 g/cc . However, aerogels are extremely fragile and, as a result, have limited practical applications. Recently, Glenn Research Center has developed a process of nano-casting polymers onto the inorganic network of silica-based aerogels increasing the strength 300 fold while only increasing the density 3 fold. By combining the process of nano-casting polymers with inorganic oxide networks other than silica, we are actively pursuing lightweight dual purpose materials. To date, thirty different inorganic oxide aerogels have been prepared using either standard sol-gel chemistry or a non-alkoxide method involving metal chloride precursors and an epoxide; epichlorohydrin, propylene oxide or trimethylene oxide, as proton scavengers. More importantly, preliminary investigations show that the residual surface hydroxyl groups on each of these inorganic oxide aerogels can be successfully crosslinked with urethane. In addition to characterizing physical and mechanical properties such as density, strength and flexibility, each of these metal oxide aerogels are being characterized for thermal and electronic conductivity and magnetic and optical properties.

  1. Aerogel Materials by Evaporative Drying: Potential for Space Applications

    NASA Technical Reports Server (NTRS)

    Plawsky, Joel L.

    1999-01-01

    Aerogel wafers were made using an evaporative drying procedure. The main steps were sol formulation, gelation, aging, capping, and drying. Of these, the most critical step was drying. Both the rate of evaporation and temperature of the system must be controlled for best results. Aerogel materials should be benchmarked against more traditional foams and current systems may have to be redesigned to make best use of aerogel strengths. Finally, the flexibility of this procedure lends itself to producing aerogel materials for many uses other than insulation. Such uses may include catalysis, sensing, and composite materials.

  2. Applications for silica-based aerogel products on an industrial scale

    SciTech Connect

    Schmidt, M.; Schwertfeger, F.

    1998-12-31

    Aerogels, nanoporous lightweight materials, were discovered more than 60 years ago. The supercritical manufacturing process and expensive raw materials typically used to produce aerogels prohibited commercialization on an industrial scale. Recently a commercially attractive ambient pressure production process was developed which will allow broader commercialization of silica-aerogel products. Some aerogel products for insulation applications and their preparation are described. Sound insulation properties including a remarkable absorption in the difficult low frequency range was found. In the case of insulation plates performance depends on binder and can be positively influenced by choosing the right binding material.

  3. Multiscale Modeling of Heat Conduction in Carbon Nanotube Aerogels

    NASA Astrophysics Data System (ADS)

    Gong, Feng; Papavassiliou, Dimitrios; Duong, Hai

    Carbon nanotube (CNT) aerogels have attracted a lot of interest due to their ultrahigh strength/weight and surface area/weight ratios. They are promising advanced materials used in energy storage systems, hydrogen storage media and weight-conscious devices such as satellites, because of their ultralight and highly porous quality. CNT aerogels can have excellent electrical conductivity and mechanical strength. However, the thermal conductivity of CNT aerogels are as low as 0.01-0.1 W/mK, which is five orders of magnitude lower than that of CNT (2000-5000 W/mK). To investigate the mechanisms for the low thermal conductivity of CNT aerogels, multiscale models are built in this study. Molecular dynamic (MD) simulations are first carried out to investigate the heat transfer between CNT and different gases (e.g. nitrogen and hydrogen), and the thermal conductance at CNT-CNT interface. The interfacial thermal resistances of CNT-gas and CNT-CNT are estimated from the MD simulations. Mesoscopic modeling of CNT aerogels are then built using an off-lattice Monte Carlo (MC) simulations to replicate the realistic CNT aerogels. The interfacial thermal resistances estimated from MD simulations are used as inputs in the MC models to predict the thermal conductivity of CNT aerogels. The volume fractions and the complex morphologies of CNTs are also quantified to study their effects on the thermal conductivity of CNT aerogels. The quantitative findings may help researchers to obtain the CNT aerogels with expected thermal conductivity.

  4. The thermal insulation difference of clothing ensembles on the dry and perspiration manikins

    NASA Astrophysics Data System (ADS)

    Xiaohong, Zhou; Chunqin, Zheng; Yingming, Qiang; Holmér, Ingvar; Gao, Chuansi; Kuklane, Kalev

    2010-08-01

    There are about a hundred manikin users around the world. Some of them use the manikin such as 'Walter' and 'Tore' to evaluate the comfort of clothing ensembles according to their thermal insulation and moisture resistance. A 'Walter' manikin is made of water and waterproof breathable fabric 'skin', which simulates the characteristics of human perspiration. So evaporation, condensation or sorption and desorption are always accompanied by heat transfer. A 'Tore' manikin only has dry heat exchange by conduction, radiation and convection from the manikin through clothing ensembles to environments. It is an ideal apparatus to measure the thermal insulation of the clothing ensemble and allows evaluation of thermal comfort. This paper compares thermal insulation measured with dry 'Tore' and sweating 'Walter' manikins. Clothing ensembles consisted of permeable and impermeable clothes. The results showed that the clothes covering the 'Walter' manikin absorbed the moisture evaporated from the manikin. When the moisture transferred through the permeable clothing ensembles, heat of condensation could be neglected. But it was observed that heavy condensation occurred if impermeable clothes were tested on the 'Walter' manikin. This resulted in a thermal insulation difference of clothing ensembles on the dry and perspiration manikins. The thermal insulation obtained from the 'Walter' manikin has to be modified when heavy condensation occurs. The modified equation is obtained in this study.

  5. Use of coconut fiber as a low-cost thermal insulator

    SciTech Connect

    Kochhar, G.S.; Manohar, K.

    1997-11-01

    Cost is one of the major factors to be considered when choosing a thermal insulator. Design engineers continuously strive to provide the best at the lowest possible cost. In the tropics climate conditions are essentially hot and humid and a cause for daily discomfort. To some extent, air-conditioning of buildings has solved this problem. The major deterrent to air-conditioning is the exorbitant cost of imported thermal insulation materials. This has prompted a search for local, low-cost but effective thermal insulation for buildings. Coconut fiber is available at minimal cost from the copra industry in Trinidad, as it is a waste product from the coconut. The viability of using coconut fiber as building thermal insulation was explored by conducting thermal conductivity tests on 200 mm X 400 mm X 60 mm thick slab-like specimens. The test equipment used was a locally designed constant temperature hot box apparatus. This apparatus was designed to test slab-like specimens under steady-state conditions. The reliability if this experimental set up was checked using Gypsum Plaster. The thermal conductivity test results for coconut fiber over the density range 30 kg/m{sup 3} to 115 kg/m{sup 3} showed the characteristic hooked shape graph for fibrous material. For the 60 mm thick specimens at a mean temperature of 39 C, a minimum thermal conductivity of 0.058 W/mK occurred at an optimum density of 85 kg/m{sup 3}. The thermal conductivity of commonly used industrial insulators, namely loose-fill expanded vermiculite, cellular glass and blanket fiber glass, at a mean temperature of 38 C are 0.066 W/mK, 0.061 W/mK and 0.052 W/mK respectively. When compared, these results show that air dried coconut fiber has far reaching potential for use as an effective building thermal insulation.

  6. Thermal Performance of Cryogenic Piping Multilayer Insulation in Actual Field Installations

    NASA Technical Reports Server (NTRS)

    Fesmire, J.; Augustnynowicz, S.; Thompson, K. (Technical Monitor)

    2002-01-01

    A standardized way of comparing the thermal performance of different pipelines in different sizes is needed. Vendor data for vacuum-insulated piping are typically given in heat leak rate per unit length (W/m) for a specific diameter pipeline. An overall k-value for actual field installations (k(sub oafi)) is therefore proposed as a more generalized measure for thermal performance comparison and design calculation. The k(sub oafi) provides a direct correspondence to the k-values reported for insulation materials and illustrates the large difference between ideal multilayer insulation (MLI) and actual MLI performance. In this experimental research study, a section of insulated piping was tested under cryogenic vacuum conditions, including simulated spacers and bending. Several different insulation systems were tested using a 1-meter-long cylindrical cryostat test apparatus. The simulated spacers tests showed significant degradation in the thermal performance of a given insulation system. An 18-meter-long pipeline test apparatus is now in operation at the Cryogenics Test Laboratory, NASA Kennedy Space Center, for conducting liquid nitrogen thermal performance tests.

  7. Experimental investigation and performance comparison of thermal insulation on a diesel engine liner

    SciTech Connect

    Samuel, G.R.

    1997-07-01

    The ever increasing need for conservation of fuel is an important factor in the design of diesel engines. The uncooled adiabatic engine emerges as a breakthrough in engine technology. Over the past few years, there have been many documented cases of successful experimentation to achieve this objective. As the number of various applications increase, it is necessary to pay close attention to improve the performance and efficiency of the engines. This paper will provide an insight into the experimental work carried out to investigate the effects of thermal insulation on a Diesel engine liner. As a first phase of experiment, performance of a ``Partially Insulated Engine ``was studied with the thermal insulation of the liner. Performance of a partially insulated engine was carried out in two different stages. First, flame sprayed ceramic coated liners of Alumina and Partially Stabilized Zirconia were tested. Second, air as the insulating medium was tested. An air gap liner with air was used as a thermal barrier around the conventional liner. The experiments were carried out in a single cylinder, four stroke, direct injection, water cooled diesel engine. The experiments were conducted at different loads and different injection timings. Test results showed that, the partially insulated engine has advantages over the conventional engine in respect of thermal efficiency, fuel consumption rate and heat losses. The necessity of reoptimizing injection timing was also examined.

  8. Particle Tracks in Aerogel

    NASA Technical Reports Server (NTRS)

    2005-01-01

    In an experiment using a special air gun, particles are shot into aerogel at high velocities. Closeup of particles that have been captured in aerogel are shown here. The particles leave a carrot-shaped trail in the aerogel. Aerogel was used on the Stardust spacecraft to capture comet particles from Comet Wild 2.

  9. Experimental study of the thermal and gasdynamic properties of insulation with perforated diffracting screens

    SciTech Connect

    Mikhal'chenko, R.S.; Getmanets, V.F.; Gorshkova, L.A.; Klipach, L.V.; Pershin, N.P.

    1984-06-01

    Presented here are the results of a study of the optical and gasdynamic characteristics of perforated diffraction screens made on the basis of nuclear filters and the thermal conductivity of vacuum-shield thermal insulations with diffraction screens. It is concluded that thanks to their combination of good optical and gasdynamic properties, perforated diffraction screens are the most promising type of shield for low-temperature and cryogenic technologies; and, the new type of vacuum-shield thermal insulation can be recommended for broad practical application in cryogenic systems, the most promising areas of application being those systems which require a maximum reduction in weight and heat flow through the thermal protection, which use vacuum-shield insulation packets of substantial thickness or which require maximum acceleration of the evacuation process. Coatings tested included aluminum, silver and copper.

  10. Prediction of clothing thermal insulation and moisture vapour resistance of the clothed body walking in wind.

    PubMed

    Qian, Xiaoming; Fan, Jintu

    2006-11-01

    Clothing thermal insulation and moisture vapour resistance are the two most important parameters in thermal environmental engineering, functional clothing design and end use of clothing ensembles. In this study, clothing thermal insulation and moisture vapour resistance of various types of clothing ensembles were measured using the walking-able sweating manikin, Walter, under various environmental conditions and walking speeds. Based on an extensive experimental investigation and an improved understanding of the effects of body activities and environmental conditions, a simple but effective direct regression model has been established, for predicting the clothing thermal insulation and moisture vapour resistance under wind and walking motion, from those when the manikin was standing in still air. The model has been validated by using experimental data reported in the previous literature. It has shown that the new models have advantages and provide very accurate prediction. PMID:16857703

  11. Metal stud wall systems -- Thermal disaster, or modern wall systems with highly efficient thermal insulation?

    SciTech Connect

    Kosny, J.; Christian, J.E.; Desjarlais, A.O.

    1997-11-01

    Because steel has higher thermal conductivity than wood and intense heat transfer occurs through the metal wall components, thermal performances of a metal stud wall are significantly lower than for similar wood stud walls. A reduction of the in-cavity R-value caused by the wood studs is about 10% in wood stud walls. That is why metal stud walls are believed to be considerably less thermally effective than similar made of wood. However, properly designed metal stud walls can be as thermally effective as wood stud walls. Relatively high R-values may be achieved by installing insulating sheathing, which is widely used as a remedy for a weak thermal performance of metal stud walls. A series of the promising metal stud wall configurations is analyzed using results of finite difference computer modeling and guarded hotbox tests. Some of these walls were designed and tested in the ORNL Building Technology Center, some were tested in other laboratories, and some walls were developed and forgotten long time ago. Also, a novel concept of combined foam-metal studs is considered. The main aim of the present paper is to prove that it is possible to build metal stud walls which perform as well as wood stud walls. The key lies in designing; metal stud wall systems have to be treated in a special way with particular consideration to the high thermal conduction of metal components. In the discussed collection of the efficient metal stud wall configurations, reductions of the in-cavity R-value caused by metal studs are between 10 and 20%.

  12. Surface modified aerogel monoliths

    NASA Technical Reports Server (NTRS)

    Leventis, Nicholas (Inventor); Johnston, James C. (Inventor); Kuczmarski, Maria A. (Inventor); Meador, Mary Ann B. (Inventor)

    2013-01-01

    This invention comprises reinforced aerogel monoliths such as silica aerogels having a polymer coating on its outer geometric surface boundary, and to the method of preparing said aerogel monoliths. The polymer coatings on the aerogel monoliths are derived from polymer precursors selected from the group consisting of isocyanates as a precursor, precursors of epoxies, and precursors of polyimides. The coated aerogel monoliths can be modified further by encapsulating the aerogel with the polymer precursor reinforced with fibers such as carbon or glass fibers to obtain mechanically reinforced composite encapsulated aerogel monoliths.

  13. Thermal Testing and Analysis of an Efficient High-Temperature Multi-Screen Internal Insulation

    NASA Technical Reports Server (NTRS)

    Weiland, Stefan; Handrick, Karin; Daryabeigi, Kamran

    2007-01-01

    Conventional multi-layer insulations exhibit excellent insulation performance but they are limited to the temperature range to which their components reflective foils and spacer materials are compatible. For high temperature applications, the internal multi-screen insulation IMI has been developed that utilizes unique ceramic material technology to produce reflective screens with high temperature stability. For analytical insulation sizing a parametric material model is developed that includes the main contributors for heat flow which are radiation and conduction. The adaptation of model-parameters based on effective steady-state thermal conductivity measurements performed at NASA Langley Research Center (LaRC) allows for extrapolation to arbitrary stack configurations and temperature ranges beyond the ones that were covered in the conductivity measurements. Experimental validation of the parametric material model was performed during the thermal qualification test of the X-38 Chin-panel, where test results and predictions showed a good agreement.

  14. Analysis of Several Test Methods about Heat Insulation Capabilities of Ceramic Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Dong, Chen; Zuo-Ming, Chu; Qiang, Zhang

    The insulation performance of the ZrO2 ceramic thermal barrier coatings prepared by the oxyacetylene flame spraying process is tested by four methods.Temperature variation curves of the specimen substrate in four different sets of coating thickness are required by testing the temperature of specimen substrate through infrared thermometer and thermocouple connected to a temperature recorder, and the test results arc analyzed with service conditions of ceramic coatings.The results show that,the data obtained by insulation performance vary with different test methods.The four test methods can reflect thermal barrier coating insulation effect and trends in different levels and qualitatively assess the performance of the coating insulation in conditions close to the actual service

  15. Effects of environmental exposure on cryogenic thermal insulation materials

    NASA Technical Reports Server (NTRS)

    Parmley, R. T.; Smith, F. J.; Glassford, A. P.; Coleman, J.; Stevenson, D. R.

    1973-01-01

    Investigation was made to optimize selection of insulation materials for reusable space vehicles which will be repeatedly operated over periods of up to ten years. Results of study are summarized in two reports. Volume I describes tests and significant findings. In Volume II, extensive test data obtained are organized in handbook form.

  16. Thermal insulation and clothing area factors of typical Arabian Gulf clothing ensembles for males and females: measurements using thermal manikins.

    PubMed

    Al-ajmi, F F; Loveday, D L; Bedwell, K H; Havenith, G

    2008-05-01

    The thermal insulation of clothing is one of the most important parameters used in the thermal comfort model adopted by the International Standards Organisation (ISO) [BS EN ISO 7730, 2005. Ergonomics of the thermal environment. Analytical determination and interpretation of thermal comfort using calculation of the PMV and PPD indices and local thermal comfort criteria. International Standardisation Organisation, Geneva.] and by ASHRAE [ASHRAE Handbook, 2005. Fundamentals. Chapter 8. American Society of Heating Refrigeration and Air-conditioning Engineers, Inc., 1791 Tullie Circle N.E., Atlanta, GA.]. To date, thermal insulation values of mainly Western clothing have been published with only minimal data being available for non-Western clothing. Thus, the objective of the present study is to measure and present the thermal insulation (clo) values of a number of Arabian Gulf garments as worn by males and females. The clothing ensembles and garments of Arabian Gulf males and females presented in this study are representative of those typically worn in the region during both summer and winter seasons. Measurements of total thermal insulation values (clo) were obtained using a male and a female shape thermal manikin in accordance with the definition of insulation as given in ISO 9920. In addition, the clothing area factors (f cl) determined in two different ways were compared. The first method used a photographic technique and the second a regression equation as proposed in ISO 9920, based on the insulation values of Arabian Gulf male and female garments and ensembles as they were determined in this study. In addition, fibre content, descriptions and weights of Arabian Gulf clothing have been recorded and tabulated in this study. The findings of this study are presented as additions to the existing knowledge base of clothing insulation, and provide for the first time data for Arabian Gulf clothing. The analysis showed that for these non-Western clothing designs, the

  17. Measuring Thermal Conductivity and Moisture Absorption of Cryo-Insulation Materials

    NASA Technical Reports Server (NTRS)

    Lambert, Michael A.

    1998-01-01

    NASA is seeking to develop thermal insulation material systems suitable for withstanding both extremely high temperatures encountered during atmospheric re-entry heating and aero- braking maneuvers, as well as extremely low temperatures existing in liquid fuel storage tanks. Currently, materials used for the high temperature insulation or Thermal Protection System (TPS) are different from the low temperature, or cryogenic insulation. Dual purpose materials are necessary to the development of reusable launch vehicles (RLV). The present Space Shuttle (or Space Transportation System, STS) employs TPS materials on the orbiter and cryo-insulation materials on the large fuel tank slung under the orbiter. The expensive fuel tank is jettisoned just before orbit is achieved and it burns up while re-entering over the Indian Ocean. A truly completely reusable launch vehicle must store aR cryogenic fuel internally. The fuel tanks will be located close to the outer surface. In fact the outer skin of the craft will probably also serve as the fuel tank enclosure, as in jet airliners. During a normal launch the combined TPS/cryo-insulation system will serve only as a low temperature insulator, since aerodynamic heating is relatively minimal during ascent to orbit. During re-entry, the combined TPS/cryo-insulation system will serve only as a high temperature insulator, since all the cryogenic fuel will have been expended in orbit. However, in the event of an.aborted launch or a forced/emergency early re-entry, the tanks will still contain fuel, and the TPS/cryo-insulation will have to serve as both low and high temperature insulation. Also, on long duration missions, such as to Mars, very effective cryo-insulation materials are needed to reduce bod off of liquid propellants, thereby reducing necessary tankage volume, weight, and cost. The conventional approach to obtaining both low and high temperature insulation, such as is employed for the X-33 and X-34 spacecraft, is to use

  18. Thermally insulated pipelines successfully move high-wax-content crude offshore Gabon

    SciTech Connect

    Hales, M.

    1982-01-25

    Three thermally insulated pipelines have been installed at a water depth of 35 m (115 ft) in Shell Gabon's Lucina Marine field. The three lines consist of two 2-km (1.24-mile) long flowlines connecting drilling and production platforms and a 3.2 km (2 mile) long loading line connecting a production platform to a storage tanker permanently moored in the field. All three pipelines are of 10.75-in. OD with rigid polyurethane-foam insulation contained in a high-density polyethylene sleeve. The pipelines have been designed with an operating temperature of 90/degree/C. (194/degree/F.). Thermal insulation was chosen because of the Lucina crude's high wax cloud point of 55/degree/C. (131/degree/F.). Without insulation, cooling of the crude in subsea pipelines would have lead to rapid wax deposition. Details of the coating and insulation of the line and riser pipe are given. For the line pipe, a thermal-insulation system consisting of polyurethane foam (PUF) within a polyethylene (PE) sleeve pipe was chosen.

  19. The total thermal insulation of the new-born baby

    PubMed Central

    Hey, E. N.; Katz, G.; O'Connell, Bridget

    1970-01-01

    1. One hundred and seventeen healthy new-born babies weighing between 0·9 and 4·8 kg at delivery have been studied during the first ten days of life, and sixteen of these babies have been studied serially for 6 weeks after birth. The babies lay supine in a draught-free environment (air speed 4-5 cm/sec) of moderate humidity. The operative temperature was between 26 and 38° C for the babies who were studied naked. 2. Total non-evaporative heat loss was calculated from simultaneous measurements of oxygen consumption, evaporative water loss and the concomitant change in mean body temperature. 3. Approximately 10% of the total body surface area was in contact with the mattress or floor. Conductive heat loss accounted for only about 5% of all non-evaporative heat loss when the naked baby was lying on a thick foam mattress, but for as much as 25% when the baby was lying in a water-jacketed chamber with a floor of clear plastic ∼ 5 mm thick. 4. Insulation to heat loss by convection and radiation varied with environmental temperature. Total specific insulation was low in a warm environment when the naked baby vasodilated, and rose by between 16 and 25% to a maximum in an environment of 31° C. It decreased significantly when the baby became physically active in environments with a temperature less than this. 5. Total specific insulation in an environment of 31° C varied with body size: it averaged 0·156° C.m2.hr/kcal in seven naked babies weighing 0·9-1·2 kg, rose to 0·190° C.m2.hr/kcal in twelve babies weighing 1·8-2·2 kg, and averaged 0·201° C.m2.hr/kcal in the thirty-four babies who weighed over 3 kg. Tissue insulation accounted for 23% of this total specific insulation in the smaller babies, and about 28% of the total in babies weighing over 3 kg. 6. Clothing ten babies in a vest, napkin and long cotton nightdress increased the total specific insulation by an average of 0·23° C.m2.hr/kcal. PMID:5503276

  20. Thermal insulation for high temperature microwave sintering operations and method thereof

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.; Morrow, M.S.

    1995-09-12

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering. 1 fig.

  1. Method of preparing thermal insulation for high temperature microwave sintering operations

    DOEpatents

    Holcombe, C.E.; Dykes, N.L.; Morrow, M.S.

    1996-07-16

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering. 1 fig.

  2. Method of preparing thermal insulation for high temperature microwave sintering operations

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Morrow, Marvin S.

    1996-01-01

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering.

  3. Thermal insulation for high temperature microwave sintering operations and method thereof

    DOEpatents

    Holcombe, Cressie E.; Dykes, Norman L.; Morrow, Marvin S.

    1995-01-01

    Superior microwave transparent thermal insulations for high temperature microwave sintering operations were prepared. One embodiment of the thermal insulation comprises granules of boron nitride coated with a very thin layer of glassy carbon made by preparing a glassy carbon precursor and blending it with boron nitride powder to form a mixture. The blended mixture is granulated to form a grit which is dried and heated to form the granules of boron nitride coated with a glassy carbon. Alternatively, grains of glassy carbon are coated with boron nitride by blending a mixture of a slurry comprising boron nitride, boric acid binder, and methyl alcohol with glassy carbon grains to form a blended mixture. The blended mixture is dried to form grains of glassy carbon coated with boron nitride. In addition, a physical mixture of boron nitride powder and glassy carbon grains has also been shown to be an excellent thermal insulation material for microwave processing and sintering.

  4. Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel

    DOEpatents

    Schreiber, R.B.; Fero, A.H.; Sejvar, J.

    1997-12-16

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor. 8 figs.

  5. Thermal insulating barrier and neutron shield providing integrated protection for a nuclear reactor vessel

    DOEpatents

    Schreiber, Roger B.; Fero, Arnold H.; Sejvar, James

    1997-01-01

    The reactor vessel of a nuclear reactor installation which is suspended from the cold leg nozzles in a reactor cavity is provided with a lower thermal insulating barrier spaced from the reactor vessel to form a chamber which can be flooded with cooling water through passive valving to directly cool the reactor vessel in the event of a severe accident. The passive valving also includes bistable vents at the upper end of the thermal insulating barrier for releasing steam. A removable, modular neutron shield extending around the upper end of the reactor cavity below the nozzles forms with the upwardly and outwardly tapered transition on the outer surface of the reactor vessel, a labyrinthine channel which reduces neutron streaming while providing a passage for the escape of steam during a severe accident, and for the cooling air which is circulated along the reactor cavity walls outside the thermal insulating barrier during normal operation of the reactor.

  6. Thermal blanket insulation for advanced space transportation systems

    NASA Technical Reports Server (NTRS)

    Pusch, Richard H.

    1985-01-01

    The feasibility of weaving Nextel ceramic and Nicalon silicon carbide yarns into integrally woven, three dimensional fluted core fabrics was demonstrated. Parallel face fabrics joined with woven fabric ribs to form triangular cross section flutes between the faces were woven into three single and one double layer configuration. High warp yarn density in the double layer configuration caused considerable yarn breakage during weaving. The flutes of all four fabrics were filled with mandrels made from Q-Fiber Felt and FRCI-20-12 to form candidate insulation panels for advanced Space Transportation Systems. Procedures for preparing and inserting the mandrels were developed. Recommendations are made on investigating alternate methods for filling the flutes with insulation, and for improving the weaving of these types of fabrics.

  7. A thermal distribution function for relativistic magnetically insulated electron flows

    SciTech Connect

    Desjarlais, M.P.; Sudan, R.N.

    1986-05-01

    A distribution function is presented that may be used to study the effects of finite temperature on the equilibrium and stability properties of magnetically insulated electron flows. This distribution function has the useful property that it generates the thoroughly studied class of constant Q = ..omega../sup 2//sub p//..cap omega../sup 2/ equilibria in its zero-temperature limit. Analytic solutions are given for the general, constant Q, zero-temperature equilibria.

  8. Process for the preparation of polycarboranylphosphazenes. [thermal insulation

    NASA Technical Reports Server (NTRS)

    Allcock, H. R.; Obran, J. P.; Scopelianos, A. G.; Fewell, L. L. (Inventor)

    1981-01-01

    A process for the preparation of polycarboranylphosphazenes is described. Polydihalophosphazenes are allowed to react at ambient temperatures for at least one hour with a lithium carborane in a suitable inert solvent. The remaining chlorine substituents of the carboranyl polyphosphazene are then replaced with aryloxy or alkoxy groups to enhance moisture resistance. The polymers give a high char yield when exposed to extreme heat and flame and can be used as insulation.

  9. Multilevel radiative thermal memory realized by the hysteretic metal-insulator transition of vanadium dioxide

    NASA Astrophysics Data System (ADS)

    Ito, Kota; Nishikawa, Kazutaka; Iizuka, Hideo

    2016-02-01

    Thermal information processing is attracting much interest as an analog of electronic computing. We experimentally demonstrated a radiative thermal memory utilizing a phase change material. The hysteretic metal-insulator transition of vanadium dioxide (VO2) allows us to obtain a multilevel memory. We developed a Preisach model to explain the hysteretic radiative heat transfer between a VO2 film and a fused quartz substrate. The transient response of our memory predicted by the Preisach model agrees well with the measured response. Our multilevel thermal memory paves the way for thermal information processing as well as contactless thermal management.

  10. Thermal radiative near field transport between vanadium dioxide and silicon oxide across the metal insulator transition

    NASA Astrophysics Data System (ADS)

    Menges, F.; Dittberner, M.; Novotny, L.; Passarello, D.; Parkin, S. S. P.; Spieser, M.; Riel, H.; Gotsmann, B.

    2016-04-01

    The thermal radiative near field transport between vanadium dioxide and silicon oxide at submicron distances is expected to exhibit a strong dependence on the state of vanadium dioxide which undergoes a metal-insulator transition near room temperature. We report the measurement of near field thermal transport between a heated silicon oxide micro-sphere and a vanadium dioxide thin film on a titanium oxide (rutile) substrate. The temperatures of the 15 nm vanadium dioxide thin film varied to be below and above the metal-insulator-transition, and the sphere temperatures were varied in a range between 100 and 200 °C. The measurements were performed using a vacuum-based scanning thermal microscope with a cantilevered resistive thermal sensor. We observe a thermal conductivity per unit area between the sphere and the film with a distance dependence following a power law trend and a conductance contrast larger than 2 for the two different phase states of the film.

  11. Anisotropic fibrous thermal insulator of relatively thick cross section and method for making same

    DOEpatents

    Reynolds, Carl D.; Ardary, Zane L.

    1979-01-01

    The present invention is directed to an anisotropic thermal insulator formed of carbon-bonded organic or inorganic fibers and having a thickness or cross section greater than about 3 centimeters. Delaminations and deleterious internal stresses generated during binder curing and carbonizing operations employed in the fabrication of thick fibrous insulation of thicknesses greater than 3 centimeters are essentially obviated by the method of the present invention. A slurry of fibers, thermosetting resin binder and water is vacuum molded into the selected insulator configuration with the total thickness of the molded slurry being less than about 3 centimeters, the binder is thermoset to join the fibers together at their nexaes, and then the binder is carbonized to form the carbon bond. A second slurry of the fibers, binder and water is then applied over the carbonized body with the vacuum molding, binder thermosetting and carbonizing steps being repeated to form a layered insulator with the binder providing a carbon bond between the layers. The molding, thermosetting and carbonizing steps may be repeated with additional slurries until the thermal insulator is of the desired final thickness. An additional feature of the present invention is provided by incorporating opacifying materials in any of the desired layers so as to provide different insulating properties at various temperatures. Concentration and/or type of additive can be varied from layer-to-layer.

  12. Waterproofing Nanostructured Aerogel-Ceramic Fiber Composites

    NASA Technical Reports Server (NTRS)

    White, Susan; Hsu, Ming Ta; Arnold, Jim (Technical Monitor)

    2001-01-01

    Aerogels are nanoporous materials which can be used to enhance the transport properties of ceramic fiber materials, to exploit their unique properties such as high porosity, large surface area, low density and low thermal conductivity. Numerous applications have been investigated. major obstacle to commercialization is that the structure of aerogels collapses due to the adsorption of water. simple and relatively cheap process has been developed to waterproof silica, alumina and alumina-silica and carbon aerogels and composites incorporating them. Previous waterproofing methods are short lived or expensive and time consuming.

  13. Development, fabrication and evaluation of composite thermal engine insulation

    NASA Technical Reports Server (NTRS)

    1973-01-01

    Foil enclosure configurations of 10 variations were fabricated and evaluated. A discussion of the thermal protection system panel design includes: (1) description of 3DSX/foil concept, (2) design environment, (3) material selection, (4) fabrication enclosure, (5) structural design, (6) thermal sizing, and (7) weight analysis. The structural design study includes foil evaluation, venting pressure loads, thermomechanical behavior, and enclosure venting (burst) pressure tests. Results of experimental demonstrations of performance and reuse capabilities are given for both thermal and acoustic testing.

  14. Developed a Remote Technique to Assess the Effectiveness of Thermal Insulation in Households in West Virginia

    NASA Astrophysics Data System (ADS)

    Vaish, Prateek

    Physical energy audits and interventional methods cannot sustain the increasing demand of assessing the effectiveness of existing thermal insulation in households. As for now, there does not exist a sufficiently accurate remote technology or method to assess the efficiency of a thermal envelope. Usually, the energy bills and the age of the furnace are good indicators of the performance of insulation in houses. To overcome the lack of availability of a proper framework to calculate the effectiveness of the thermal envelope, a standard methodology using multiple linear regression and temperature data acquired from a house has been developed. The major aim of the experiment was to develop a model equation which will assess the effectiveness of insulation in a house in West Virginia. If developed futher, the model will be a very useful tool for energy auditors and consultants to help house owners understand the behavior of thermal insulation in their house. The model requires four variables for input which are: 1) area of the house, 2) number of people in the house, 3) temperature difference (inside and ambient) and 4) air changes per hour inside the house. Extensive data acquisition was performed to develop a robust model. The model can now be used with minimum understanding of underlying concepts and can assess the effectiveness of thermal barrier which otherwise is very difficult to determine.

  15. Reentry thermal protection from Pioneer F RTG insulation material

    NASA Technical Reports Server (NTRS)

    Vorreiter, J. W.

    1972-01-01

    Ablation tests were performed on the insulation material used in the Pioneer F radioisotope thermoelectric generator (RTG) in the Ames Arc-Heated Planetary-Gas Wind Tunnel. Test results indicate that the material, trade name Min-K 1301, should experience little ablation for heat transfer rates below 40 BTU/sq ft-sec. If the current design were to be changed so that the various pieces of Min-K were fastened or interlocked together the total amount of heat delivered to the RTG heat source during an earth orbital decay reentry would be reduced by at least 22.7%.

  16. A Method to have Multi-Layer Thermal Insulation Provide Damage Detection

    NASA Technical Reports Server (NTRS)

    Woodward, Stanley E.; Taylor, Bryant D.; Jones, Thomas W.; Shams, Qamar A.; Lyons, Frankel; Henderson, Donald

    2007-01-01

    Design and testing of a multi-layer thermal insulation system that also provides debris and micrometeorite damage detection is presented. One layer of the insulation is designed as an array of passive open-circuit electrically conductive spiral trace sensors. The sensors are a new class of sensors that are electrically open-circuits that have no electrical connections thereby eliminating one cause of failure to circuits. The sensors are powered using external oscillating magnetic fields. Once electrically active, they produce their own harmonic magnetic fields. The responding field frequency changes if any sensor is damaged. When the sensors are used together in close proximity, the inductive coupling between sensors provides a means of telemetry. The spiral trace design using reflective electrically conductive material provides sufficient area coverage for the sensor array to serves as a layer of thermal insulation. The other insulation layers are designed to allow the sensor s magnetic field to permeate the insulation layers while having total reflective surface area to reduce thermal energy transfer. Results of characterizing individual sensors and the sensor array s response to punctures are presented. Results of hypervelocity impact testing using projectiles of 1-3.6 millimeter diameter having speeds ranging from 6.7-7.1 kilometers per second are also presented.

  17. Effective thermal conductivity determination for low-density insulating materials

    NASA Technical Reports Server (NTRS)

    Williams, S. D.; Curry, D. M.

    1978-01-01

    That nonlinear least squares can be used to determine effective thermal conductivity was demonstrated, and a method for assessing the relative error associated with these predicted values was provided. The differences between dynamic and static determination of effective thermal conductivity of low-density materials that transfer heat by a combination of conduction, convection, and radiation were discussed.

  18. 7 CFR 3300.13 - Determination of the efficiency of the thermal appliances as installed in the insulated body.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... Determination of the efficiency of the thermal appliances as installed in the insulated body. In determining the efficiency of a thermal appliance with respect to maintaining a prescribed temperature inside the body, the... appliances as installed in the insulated body. 3300.13 Section 3300.13 Agriculture Regulations of...

  19. 7 CFR 3300.13 - Determination of the efficiency of the thermal appliances as installed in the insulated body.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Determination of the efficiency of the thermal appliances as installed in the insulated body. 3300.13 Section 3300.13 Agriculture Regulations of the... Determination of the efficiency of the thermal appliances as installed in the insulated body. In determining...

  20. 7 CFR 3300.13 - Determination of the efficiency of the thermal appliances as installed in the insulated body.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Determination of the efficiency of the thermal appliances as installed in the insulated body. 3300.13 Section 3300.13 Agriculture Regulations of the... Determination of the efficiency of the thermal appliances as installed in the insulated body. In determining...

  1. 7 CFR 3300.13 - Determination of the efficiency of the thermal appliances as installed in the insulated body.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Determination of the efficiency of the thermal appliances as installed in the insulated body. 3300.13 Section 3300.13 Agriculture Regulations of the... Determination of the efficiency of the thermal appliances as installed in the insulated body. In determining...

  2. 7 CFR 3300.13 - Determination of the efficiency of the thermal appliances as installed in the insulated body.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Determination of the efficiency of the thermal appliances as installed in the insulated body. 3300.13 Section 3300.13 Agriculture Regulations of the... Determination of the efficiency of the thermal appliances as installed in the insulated body. In determining...

  3. The research Of Multilayer Thermal Insulation With Mechanical Properties Based On Model Analysis Test

    NASA Astrophysics Data System (ADS)

    Lianhua, Yin

    The heat shield of aircraft is made of the major thrusts structure with multilayer thermal insulation part. For protecting against thermo-radiation from larger thrusting force engine,the heat shield is installed around this engine nearby.The multilayer thermal insulation part with multilayer radiation/reflection structure is made of reflection layer and interval layer.At vacuum condition,these materials is higher heat insulation capability than other material,is applied for lots of pats on aircraft extensively.But because of these material is made of metal and nonmetal,it is impossible to receive it's mechanical properties of materials from mechanical tests.These paper describes a new measure of mechanical properties of materials in the heat shield based on model analysis test.At the requirement for the first order lateral frequency,these measure provide for the FEM analysis foundation on the optimization structure of the heat shield.

  4. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    PubMed Central

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  5. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment.

    PubMed

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-01-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor. PMID:26671673

  6. Mechanically Stretchable and Electrically Insulating Thermal Elastomer Composite by Liquid Alloy Droplet Embedment

    NASA Astrophysics Data System (ADS)

    Jeong, Seung Hee; Chen, Si; Huo, Jinxing; Gamstedt, Erik Kristofer; Liu, Johan; Zhang, Shi-Li; Zhang, Zhi-Bin; Hjort, Klas; Wu, Zhigang

    2015-12-01

    Stretchable electronics and soft robotics have shown unsurpassed features, inheriting remarkable functions from stretchable and soft materials. Electrically conductive and mechanically stretchable materials based on composites have been widely studied for stretchable electronics as electrical conductors using various combinations of materials. However, thermally tunable and stretchable materials, which have high potential in soft and stretchable thermal devices as interface or packaging materials, have not been sufficiently studied. Here, a mechanically stretchable and electrically insulating thermal elastomer composite is demonstrated, which can be easily processed for device fabrication. A liquid alloy is embedded as liquid droplet fillers in an elastomer matrix to achieve softness and stretchability. This new elastomer composite is expected useful to enhance thermal response or efficiency of soft and stretchable thermal devices or systems. The thermal elastomer composites demonstrate advantages such as thermal interface and packaging layers with thermal shrink films in transient and steady-state cases and a stretchable temperature sensor.

  7. Optical shock waves in silica aerogel.

    PubMed

    Gentilini, S; Ghajeri, F; Ghofraniha, N; Di Falco, A; Conti, C

    2014-01-27

    Silica aerogels are materials well suited for high power nonlinear optical applications. In such regime, the non-trivial thermal properties may give rise to the generation of optical shock waves, which are also affected by the structural disorder due to the porous solid-state gel. Here we report on an experimental investigation in terms of beam waist and input power, and identify various regimes of the generation of wave-breaking phenomena in silica aerogels. PMID:24515173

  8. Thermal Performance Comparison of Glass Microsphere and Perlite Insulation Systems for Liquid Hydrogen Storage Tanks

    NASA Astrophysics Data System (ADS)

    Sass, J. P.; Fesmire, J. E.; Nagy, Z. F.; Sojourner, S. J.; Morris, D. L.; Augustynowicz, S. D.

    2008-03-01

    A technology demonstration test project was conducted by the Cryogenics Test Laboratory at the Kennedy Space Center (KSC) to provide comparative thermal performance data for glass microspheres, referred to as bubbles, and perlite insulation for liquid hydrogen tank applications. Two identical 1/15th scale versions of the 3,200,000 liter spherical liquid hydrogen tanks at Launch Complex 39 at KSC were custom designed and built to serve as test articles for this test project. Evaporative (boil-off) calorimeter test protocols, including liquid nitrogen and liquid hydrogen, were established to provide tank test conditions characteristic of the large storage tanks that support the Space Shuttle launch operations. This paper provides comparative thermal performance test results for bubbles and perlite for a wide range of conditions. Thermal performance as a function of cryogenic commodity (nitrogen and hydrogen), vacuum pressure, insulation fill level, tank liquid level, and thermal cycles will be presented.

  9. Ultralow lattice thermal conductivity in topological insulator TlBiSe2

    NASA Astrophysics Data System (ADS)

    Ding, Guangqian; Carrete, Jesús; Li, Wu; Gao, G. Y.; Yao, Kailun

    2016-06-01

    We present ab-initio calculations of the phonon thermal transport properties of topological insulator TlBiSe2. Our results point to a very low lattice thermal conductivity, comparable or lower than those of some popular good thermoelectric materials. Furthermore, we find a slight thermal anisotropy between the in-plane and cross-plane directions in TlBiSe2, markedly smaller than those of van-der-Waals topological insulators explored so far. These conclusions are confirmed and explained by comprehensive analysis of the phonon spectrum of TlBiSe2. The combination of ultralow lattice thermal conductivity and small anisotropy makes TlBiSe2 a promising candidate for thermoelectric applications.

  10. Thermal Insulation Performance of Textile Structures for Spacesuit Applications at Martian Pressure and Temperature

    NASA Technical Reports Server (NTRS)

    Orndoff, Evelyne; Trevino, Luis A.

    2000-01-01

    Protection of astronauts from the extreme temperatures in the space environment has been provided in the past using multi-layer insulation in ultra-high vacuum environments of low earth orbit and the lunar surface. For planetary environments with residual gas atmospheres such as Mars with ambient pressures between 8 to 14 hPa (8 to 14 mbar), new protection techniques are required because of the dominating effect of the ambient gas on heat loss through the insulation. At Mars ambient pressure levels, the heat loss can be excessive at expected suit external temperatures of 172 K with state-of-the-art suit insulation, requiring an active heat source and its accompanying weight and volume penalties. Micro-fibers have been identified as one potential structure to reduce the heat losses, but existing fundamental data on fiber heat transfer at low pressure is lacking for integrated fabric structures. This baseline study presents insulation performance test data at different pressures and fabric loads for selected polyesters and aramids as a function of fiber density, fiber diameter, fabric density, and fabric construction. A set of trend data of thermal conductivity versus ambient pressure is presented for each fiber and fabric construction design to identify the design effects on thermal conductivity at various ambient pressures, and to select a fiber and fabric design for further development as a suit insulation. The trend data also shows the pressure level at which thermal conductivity approaches a minimum, below which no further improvement is possible for a given fiber and fabric design. The pressure levels and resulting thermal conductivities from the trend data can then be compared to the ambient pressure at a planetary surface, Mars for example, to determine if a particular fiber and fabric design has potential as a suit insulation.

  11. Effects of a thermal-insulating mouse pad on temperature of forearm and hand during computer tasks.

    PubMed

    Meijer, Eline M; Formanoy, Margriet A G; Visser, Bart; Sluiter, Judith K; Frings-Dresen, Monique H W

    2006-07-15

    This laboratory experiment studied the effects of a thermal-insulating mouse pad on arm temperature and comfort during computer work. Fourteen subjects performed two 20-min computer tasks (a mouse task and a combined task alternating keyboard and mouse use), under three conditions, namely with: 1) a thermal-insulating pad; 2) a placebo pad; 3) no pad (desktop). The temperatures of the forearm, wrist, hand and fingers were measured with four thermocouples. Comfort and discomfort were determined by two visual analogue scales. No arm temperature differences were found between the experimental conditions after performing the combination task in any location. After the mouse task, however, arm temperature decreased significantly less with the thermal-insulating mouse pad than with the placebo pad. The thermal-insulating pad was rated as more comfortable and less uncomfortable than a regular desktop during mouse tasks. A large size is recommended for the thermal-insulating pad. PMID:16801230

  12. Thermal insulation material comprising a mixture of silk and synthetic fiber staple

    SciTech Connect

    Aldrich, W.E.

    1983-08-23

    An improved thermal insulation material is disclosed, comprising a carded web containing 30 to 80 wt. %, preferably 50 wt. % silk, the balance being crimped, hollow polyester staple or very low denier solid cross section polyester filaments. The carded web is uniformly impregnated with a thermosetting resin to form a bat which is employed as a filler for garments, sleeping bags and the like.

  13. Flight Performance of an Advanced Thermal Protection Material: Toughened Uni-Piece Fibrous Insulation

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Gordon, Michael P.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    The flight performance of a new class of low density, high temperature thermal protection materials (TPM) is described and compared to "standard" Space Shuttle TPM. This new functionally gradient material designated as Toughened Uni-Piece Fibrous Insulation (TUFI), was bonded on a removable panel attached to the base heat shield of Orbiter 105, Endeavour.

  14. Flight Performance of an Advanced Thermal Protection Material: Toughened Uni-Piece Fibrous Insulation

    NASA Technical Reports Server (NTRS)

    Leiser, Daniel B.; Gordon, Michael P.; Rasky, Daniel J. (Technical Monitor)

    1995-01-01

    The flight performance of a new class of low density, high temperature, thermal protection materials (TPM), is described and compared to "standard" Space Shuttle TPM. This new functionally gradient material designated as Toughened Uni-Piece Fibrous Insulation (TUFI), was bonded on a removable panel attached to the base heatshield of Orbiter 105, Endeavor.

  15. THERMAL INSULATION PROPERTIES OF BIODEGRADABLE, CELLULOSIC-BASED NONWOVEN COMPOSITES FOR AUTOMOTIVE APPLICATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Moldable, cellulosic-based nonwoven composites with excellent thermal insulation properties were fabricated from kenaf, jute, flax, and waste cotton using recycled polyester and substandard polypropylene. The composites of these fibers have excellent shape stability and high tensile and flexural pro...

  16. Thermal and Energy Performance of Conditioned Building Due To Insulated Sloped Roof

    NASA Astrophysics Data System (ADS)

    Irwan, Suhandi Syiful; Ahmed, Azni Zain; Zakaria, Nor Zaini; Ibrahim, Norhati

    2010-07-01

    For low-rise buildings in equatorial region, the roof is exposed to solar radiation longer than other parts of the envelope. Roofs are to be designed to reject heat and moderate the thermal impact. These are determined by the design and construction of the roofing system. The pitch of roof and the properties of construction affect the heat gain into the attic and subsequently the indoor temperature of the living spaces underneath. This finally influences the thermal comfort conditions of naturally ventilated buildings and cooling load of conditioned buildings. This study investigated the effect of insulated sloping roof on thermal energy performance of the building. A whole-building thermal energy computer simulation tool, Integrated Environmental Solution (IES), was used for the modelling and analyses. A building model with dimension of 4.0 m × 4.0 m × 3.0 m was designed with insulated roof and conventional construction for other parts of the envelope. A 75 mm conductive insulation material with thermal conductivity (k-value) of 0.034 Wm-1K-1 was installed underneath the roof tiles. The building was modelled with roof pitch angles of 0° , 15°, 30°, 45°, 60° and simulated for the month of August in Malaysian climate conditions. The profile for attic temperature, indoor temperature and cooling load were downloaded and evaluated. The optimum roof pitch angle for best thermal performance and energy saving was identified. The results show the pitch angle of 0° is able to mitigate the thermal impact to provide the best thermal condition with optimum energy savings. The maximum temperature difference between insulated and non-insulted roof for attic (AtticA-B) and indoor condition (IndoorA-B) is +7.8 °C and 0.4 °C respectively with an average energy monthly savings of 3.9 %.

  17. Processing of thermal insulation materials with controlled porosity

    SciTech Connect

    Lyckfeldt, O.; Liden, E.; Carlsson, R.

    1995-08-01

    Slip-cast cordierite-based materials with reduced thermal conductivity have been manufactured with controlled introduction of porosity. The porosity was obtained by addition of different kinds of fillers (hollow Al-silicate spheres, paraffin, polystyrene, carbon black or starch particles). The processing and the ultimate thermal and mechanical properties were evaluated. The results showed that additions of corn or potato starch gave the most favourable concept, considering the processing and porosity control. A homogeneous distribution of spherical pores with the sizes 5-25 or 15-40 {mu}m was obtained after sintering. Slip-cast cordierite with 37% porosity had a thermal conductivity of 1.7 W/mK (compared with 3.7 W/mK for fully dense cordierite), and a bending strength above 50 MPa. The porosity effect correlated very well to theoretical models by Maxwell and, hence, the thermal conductivity of the porous ceramic material could be predicted.

  18. Determination of physical properties of fibrous thermal insulation

    NASA Astrophysics Data System (ADS)

    Tilioua, A.; Libessart, L.; Joulin, A.; Lassue, S.; Monod, B.; Jeandel, G.

    2012-10-01

    The objective of this study is to characterize both experimentally and theoretically, conductive and radiative heat transfer within polyester batting. This material is derived from recycled bottles (PET) with fibres of constant diameters. Two other mineral and plant fibrous insulation materials, (glass wool and hemp wool) are also characterized for comparative purposes. To determine the overall thermophysical properties of the tested materials, heat flux measurement are carried out using a device developed in house. The radiative properties of the material are determined by an inverse method based on measurements of transmittance and reflectance using a FTIR spectrometer and by solving the equation of radiative heat transfer. These measures are compared to results of numerical simulations.

  19. Aerogel Projects Ongoing in MSFC's Engineering Directorate

    NASA Technical Reports Server (NTRS)

    Shular, David A.; Smithers, Gweneth A.; Plawsky, Joel L.; Whitaker, Ann F. (Technical Monitor)

    2000-01-01

    When we speak of an aerogel material, we are referring more to process and structure am to a specific substance. Aerogel, considered the lightest solid material, has been made from silica for seventy years. Resorcinol-formaldehyde, organic aerogels have been developed more recently. However, aerogel can be made from almost any type of substance, even lead. Because an aerogel is mostly air (about 99 %), the solid substance used will affect the weight very little. The term "aerogel" connotes the sol-gel process used to manufacture the material. The aerogel begins as a liquid "sol," becomes a solid "alcogel," and is then dried to become an "aerogel." The final product has a unique structure, useful for exploitation. It is an "open pore" system with nano-sized particles and pores, has very high surface area, and is highly interconnected. Besides low weight, aerogels have ultimate (lowest) values in other properties: thermal conductivity, refractive index, sound speed, and dielectric constant. Aerogels were first prepared in 1931 by Steven Kistler, who used a supercritical drying step to replace the liquid in a gel with air, preserving the structure (1). Kistler's procedure involved a water-to-alcohol exchange step; in the 1970's, this step was eliminated when a French investigator introduced the use of tetramethylorthosilicate. Still, alcohol drying involved dangerously high temperatures and pressures. In the 1980's, the Microstructured Materials Group at Berkeley Laboratory found that the alcohol in the gel could be replaced with liquid carbon dioxide before supercritical drying, which greatly improved safety (2). 'Me most recent major contribution has been that of Deshpande, Smith and Brinker in New Mexico, who are working to eliminate the supercritical drying step (3). When aerogels were first being developed, they were evaporatively dried. However, the wet gel, when dried, underwent severe shrinkage and cracking; this product was termed "xerogel." When the

  20. Validation of the thermal effect of roof with the Spraying and green plants in an insulated building

    SciTech Connect

    Zhou, Nan; Gao, Weijun; Nishida, Masaru; Ojima, Toshio

    2004-08-08

    In recent years, roof-spraying and rooftop lawns have proven effective on roofs with poor thermal insulation. However, the roofs of most buildings have insulating material to provide thermal insulation during the winter. The effects of insulation has not previously been quantified. In this study, the authors collected measurements of an insulated building to quantify the thermal effects of roof-spraying and rooftop lawns. Roof-spraying did not significantly reduce cooling loads and required significant amounts of water. The conclusion is that roof spraying is not suitable for buildings with well-insulated roofs. Rooftop lawns, however, significantly stabilized the indoor temperature while additionally helping to mitigate the heat island phenomenon.

  1. Aerogel in Hand

    NASA Technical Reports Server (NTRS)

    2005-01-01

    Though ghostly in appearance like an hologram, aerogel is very solid. It feels like hard styrofoam to the touch. Aerogel was used on the Stardust spacecraft to capture comet particles from Comet Wild 2.

  2. Steady-State Thermal Performance Evaluation of Steel-Framed Wall Assembly with Local Foam Insulation

    SciTech Connect

    Kosny, Jan; Biswas, Kaushik; Childs, Phillip W

    2010-01-01

    During January and May, 2009, two configurations of steel-framed walls constructed with conventional 2 4 steel studs insulated with R-19 ~14cm. (5.5-in. thick) and R-13 ~9cm. (3.5-in. thick) fiberglass insulation batts were tested in the Oak Ridge National Laboratory (ORNL) guarded hot-box using ASTM C1363 test procedure. The first test wall used conventional 2 4 steel studs insulated with 2.5-cm. (1-in.) thick foam profiles, called stud snugglers. These stud snugglers converted the 2 4 wall assembly into a 2 6 assembly allowing application of R-19 fiberglass insulation. The second wall tested for comparison was a conventional 2 4 steel stud wall using R-13 insulation batts. Further, numerical simulations were performed in order to evaluate the steady-state thermal performance of various wood- and steel-framed wall assemblies. The effects of adding the stud-snugglers to the wood and steel studs were also investigated numerically. Different combinations of insulation and framing factor were used in the simulations.

  3. Insulation commonality assessment (phase 1). Volume 2: Section 7.0 through 16.0. [evaluation of materials used for spacecraft thermal insulation

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The heat transfer characteristics of various materials used for the thermal insulation of spacecraft are discussed. Techniques for conducting thermal performance analysis, structural performance analysis, and dynamic analysis are described. Processes for producing and finishing the materials are explained. The methods for determining reliability, system safety, materials tests, and design effectiveness are explained.

  4. Standardization in Cryogenic Insulation Systems Testing and Performance Data

    NASA Astrophysics Data System (ADS)

    Fesmire, James E.

    The close relationship between industrial energy use and cryogenics drives the need for optimized thermal insulation systems. Emerging cryofuels usage is enabled by adequate isolation of the liquid hydrogen or liquefied natural gas from the ambient environment. Thermal performance data for the total insulation system, as rendered, are essential for both engineering designs and cost-benefit decisions involving comparisons among alternatives. These data are obtained through rigorous testing with suitable apparatus and repeatable methods. Properly defined terminology, analysis, and reporting are also vital. Advances in cryogenic insulation test apparatus and methods have led to the recent addition of two new technical standards of ASTM International: C1774 - Standard Guide for Thermal Performance Testing of Cryogenic InsulationSystems and C740 - Standard Guide for Evacuated Reflective Cryogenic Insulation. Among the different techniques described in the new standards is the cylindrical boiloff calorimeter for absolute heat measurement over the full range of vacuum pressure conditions. The details of this apparatus, test method, and data analysis are given. Benchmark thermal performance data, including effective thermal conductivity (ke) and heat flux (q) for the boundary temperatures of 293 K and 77 K, are given for a number of different multilayer insulation (MLI) systems in comparison with data for other commonly-used insulation systems including perlite powder, fiberglass, polyurethane foam, and aerogels.

  5. Thermal resistance of attic loose-fill insulations decreases under simulated winter conditions

    SciTech Connect

    Graves, R.S.; Wilkes, K.E.; McElroy, D.L.

    1994-05-01

    Two absolute techniques were used to measure the thermal resistance of attic loose-fill insulations: the Large Scale Climate Simulator (LSCS) and the Unguarded Thin-Heater Apparatus (UTHA). Two types of attic loose-fill insulations (unbonded and bonded/cubed) were tested under simulated winter conditions. To simulate winter conditions for an attic insulation, the specimens were tested with heat flow up, large temperature differences, and an air gap. The specimens were tested either with a constant mean temperature (30 or 21{degrees}C) and an increasing temperature difference or with a constant base temperature (21{degrees}C) and an increasing temperature difference (i.e., a decreasing mean temperature). The UTHA test specimens had a nominal thickness of 0.2 m of loose-fill insulation. The LSCS test specimens had a nominal thickness of 0.3 m of loose-fill insulation contained in a 4.2 by 5 m attic test module with a gypsum board base. The module had a gabled attic with a 5 in 12 slope roof. The tests yielded the surface-to-surface thermal resistance, R, which includes the thermal resistance due to gypsum, insulation, and any wood joists. Tests with and without an air gap were conducted in the UTHA. Surface-to-surface thermal resistance results from the LSCS and the UTHA show similar trends for these two types of loose-fill insulation when tested under simulated winter conditions. Tests with no air gap gave values of R that agreed with the bag label R-value for the insulations; R increased with lower mean temperatures. These no-gap values of R were 2 to 5% greater than the values of R obtained with an air gap for temperature differences of less than 22{degrees}C. For larger temperature differences R decreased, and at temperature differences of over 40{degrees}C, the R values were 50% less than those at small temperature differences.

  6. Thermal Aging Characteristics of Insulation Paper in Mineral Oil under Overloaded Operating Transformers

    NASA Astrophysics Data System (ADS)

    Miyagi, Katsunori; Oe, Etsuo; Yamagata, Naoki; Miyahara, Hideyuki

    A sudden capacity increase in demand during the summer peak, or in contingencies such as malfunctioning transformers, may cause overload for normal transformers. In this paper, on the basis of examples of overloaded transformer operation in distributing substations, thermal aging testing in oil was carried out under various overload patterns, such as short time overload and long time overload, but with the winding insulation paper's life loss kept constant. From the results, various characteristics such as mean degree of polymerization and productions of furfural and (CO2+CO), and their effects on the life loss of the insulation paper were obtained.

  7. Arcjet Testing and Thermal Model Development for Multilayer Felt Reusable Surface Insulation

    NASA Technical Reports Server (NTRS)

    Milos, Frank S.; Scott, Carl Douglas; Papa, Steven V.

    2012-01-01

    Felt Reusable Surface Insulation was used extensively on leeward external surfaces of the Shuttle Orbiter, where the material is reusable for temperatures up to 670 K. For application on leeward surfaces of the Orion Multi-Purpose Crew Vehicle, where predicted temperatures reach 1620 K, the material functions as a pyrolyzing conformal ablator. An arcjet test series was conducted to assess the performance of multilayer Felt Reusable Surface Insulation at high temperatures, and a thermal-response, pyrolysis, and ablation model was developed. Model predictions compare favorably with the arcjet test data

  8. Thermal insulation performance of flexible piping for use in HTS power cables

    NASA Astrophysics Data System (ADS)

    Fesmire, J. E.; Augustynowicz, S. D.; Demko, J. A.

    2002-05-01

    High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 kelvin (K) are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping. This experimental study performed at the Cryogenics Test Laboratory of NASA Kennedy Space Center provides a framework for the development of cost-effective, efficient thermal insulation systems that will support these long-distance flexible lines containing HTS power cables. The overall thermal performance of the insulation system for a rigid configuration and for a flexible configuration, simulating a flexible HTS power cable, was determined by the steady-state liquid nitrogen boiloff method under the full range of vacuum levels. Two different cylindrically rolled material systems were tested: a standard MLI and a layered composite insulation (LCI). Comparisons of ideal MLI, MLI on rigid piping, and MLI between flexible piping are presented.

  9. Thermal Insulation Performance of Flexible Piping for Use in HTS Power Cables

    NASA Technical Reports Server (NTRS)

    Fesmire, James E.; Augustynowicz, S. D.; Demko, J. A.; Thompson, Karen (Technical Monitor)

    2001-01-01

    High-temperature superconducting (HTS) cables that typically operate at temperatures below 80 K are being developed for power transmission. The practical application of HTS power cables will require the use of flexible piping to contain the cable and the liquid nitrogen coolant. A study of thermal performance of multilayer insulation (MLI) was conducted in geometries representing both rigid and flexible piping. This experimental study performed at the Cryogenics Test Laboratory of NASA Kennedy Space Center provides a framework for the development of cost-effective, efficient thermal insulation systems that will support these long-distance flexible lines containing HTS power cables. The overall thermal performance of the insulation system for a rigid configuration and for a flexible configuration, simulating a flexible HTS power cable, was determined by the steady-state liquid nitrogen boiloff method under the full range of vacuum levels. Two different cylindrically rolled material systems were tested: a standard MLI and a layered composite insulation (LCI). Comparisons of ideal MLI, MLI on rigid piping, and MLI between flexible piping are presented.

  10. Thermal resistance of perlite-based evacuated insulations for refrigerators

    SciTech Connect

    Yarbrough, D.W.; Graves, R.S.; Weaver, F.J.; McElroy, D.L.

    1986-09-01

    The thermal resistances of two side panels which were cut from imported refrigerators and of a single, newly manufactured evacuated packet were measured using a linear heat flow technique. The panels were composites of foamed-in-place urethane surrounding perlite-filled evacuated packets. One panel contained an apparently punctured packet and was found to have a thermal resistance at 300 K in the range 0.617 to 0.950 m/sup 2/ x K/W for 2.54 cm (3.5 to 5.4 ft/sup 2/ x h x /sup 0/F/Btu for 1.0 in.). A second apparently undamaged packet had thermal resistances in the range 1.66 to 2.45 m/sup 2/ x K/W for 2.54 cm (9.4 to 13.9 ft/sup 2/ x h x /sup 0/F/Btu for 1.0 in.). The internal pressure of the undamaged packet was calculated to be in the range 100 to 1000 Pa by comparing packet thermal properties with apparent thermal conductivities, k/sub a/, obtained as a function of pressure for the perlite removed from the damaged packet. The thermal resistance for the single evacuated packet was determined by framing the packet with polyisocyanurate of known k/sub a/ and measuring heat flow across the assembly. This yielded a thermal resistance of 18.1 ft/sup 2/ x h x /sup 0/F/Btu for 1.0 in. The k/sub a/ values of two domestic perlites and the perlite removed from the punctured refrigerator packet were measured at 300 K and pressures from atmospheric down to about 5 Pa using a radial heat flow technique. Near 1 atm the k/sub a/ of fine domestic perlite at a density of 246 kg/m/sup 3/ was 5% above that of the foreign perlite at 225 kg/m/sup 3/, but the domestic product had a k/sub a/ up to 45% greater than that of the foreign product under vacuum. The mean particle diameter of the imported perlite was near 13 ..mu..m, while the mean particle diameter of the domestic product was near 21 ..mu..m.

  11. Nanoporous Silica Thermal Insulation for Space Shuttle Cryogenic Tanks: A Case Study

    NASA Technical Reports Server (NTRS)

    Noever, David A.

    1999-01-01

    Nanoporous silica (with typical 10-50 nm porous radii) has been benchmarked for thermal insulators capable of maintaining a 150 K/cm temperature gradient. For cryogenic use in aerospace applications, the combined features for low-density, high thermal insulation factors, and low temperature compatibility are demonstrated in a prototype sandwich structure between two propulsion tanks. Theoretical modelling based on a nanoscale fractal structure suggest that the thermal conductivity scales proportionally (exponent, 1.7) with the material density-lower density increases the thermal insulation rating. Computer simulations, however, support the optimization tradeoff between material strength (Young moduli, proportional to density with exponent, 3.7), the characteristic (colloidal silica, less than 5 nm) particle size, and the thermal rating. The results of these simulations indicate that as nanosized particles are incorporated into the silica backbone, the resulting physical properties will be tailored by the smallest characteristic length and their fractal interconnections (dimension and fractal size). The application specifies a prototype panel which takes advantage of the processing flexibility inherent in sol-gel chemistry.

  12. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Stamokostas, Georgios; Lapas, Panteleimon; Fiete, Gregory A.

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  13. Thermal conductivity of magnetic insulators with strong spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Lapas, Panteleimon; Stamokostas, Georgios; Fiete, Gregory

    2015-03-01

    We study the influence of spin-orbit coupling on the thermal conductivity of various types of magnetic insulators. In the absence of spin-orbit coupling and orbital-degeneracy, the strong-coupling limit of Hubbard interactions at half filling can often be adequately described in terms of a pure spin Hamiltonian of the Heisenberg form. However, in the presence of spin-orbit coupling the resulting exchange interaction can become highly anisotropic. The effect of the atomic spin-orbit coupling, taken into account through the effect of magnon-phonon interactions and the magnetic order and excitations, on the lattice thermal conductivity of various insulating magnetic systems is studied. We focus on the regime of low temperatures where the dominant source of scattering is two-magnon scattering to one-phonon processes. The thermal current is calculated within the Boltzmann transport theory. We are grateful for financial support from NSF Grant DMR-0955778.

  14. Evaluating Dimethyldiethoxysilane for use in Polyurethane Crosslinked Silica Aerogels

    NASA Technical Reports Server (NTRS)

    Randall, Jason P.; Meador, Mary Ann B.; Jana, Sadhan C.

    2008-01-01

    Silica aerogels are highly porous materials which exhibit exceptionally low density and thermal conductivity. Their "pearl necklace" nanostructure, however, is inherently weak; most silica aerogels are brittle and fragile. The strength of aerogels can be improved by employing an additional crosslinking step using isocyanates. In this work, dimethyldiethoxysilane (DMDES) is evaluated for use in the silane backbone of polyurethane crosslinked aerogels. Approximately half of the resulting aerogels exhibited a core/shell morphology of hard crosslinked aerogel surrounding a softer, uncrosslinked center. Solid state NMR and scanning electron microscopy results indicate the DMDES incorporated itself as a conformal coating around the outside of the secondary silica particles, in much the same manner as isocyanate crosslinking. Response surface curves were generated from compression data, indicating levels of reinforcement comparable to that in previous literature, despite the core/shell morphology.

  15. Thermal stress analysis of reusable surface insulation for shuttle

    NASA Technical Reports Server (NTRS)

    Ojalvo, I. U.; Levy, A.; Austin, F.

    1974-01-01

    An iterative procedure for accurately determining tile stresses associated with static mechanical and thermally induced internal loads is presented. The necessary conditions for convergence of the method are derived. An user-oriented computer program based upon the present method of analysis was developed. The program is capable of analyzing multi-tiled panels and determining the associated stresses. Typical numerical results from this computer program are presented.

  16. Characterization of Min-K TE-1400 Thermal Insulation

    SciTech Connect

    Hemrick, James Gordon; Lara-Curzio, Edgar; King, James

    2008-07-01

    Min-K 1400TE insulation material was characterized at Oak Ridge National Laboratory for use in structural applications under gradient temperature conditions. Initial compression testing was performed at room temperature at various loading rates ranging between 5 and 500 psi/hour (≈35 and 3500 kPa/hour) to determine the effect of sample size and test specimen geometry on the compressive strength of Min-K. To determine the loading rates that would be used for stress relaxation testing, compression tests were next carried out at various levels followed by stress relaxation under constant strain at temperatures of 650, 850, and 900oC. Additional high temperature compression testing was performed with samples loaded at a rate of 53 psi/hour (365 kPa/hour) in three load steps of 50, 100 and 200 psi (345, 690, and 1380 kPa) with quick unload/load cycles between steps and followed by a hold period in load control (3 to 100 hours) to allow for sample creep. Testing was carried out at 190, 382, 813, and 850oC. Isothermal stress relaxation testing was performed at temperatures of 190, 382, 813, and 850oC and initial loads of 100 and 200 psi (690 and 1380 kPa). Gradient stress relaxation testing was intended to be performed at temperatures of 850/450oC and 450/190oC with initial loads of 100 or 200 psi (690 and 1380 kPa) performed under constant strain utilizing a twelve-step loading scheme with loading every half hour at a rate of 5.56% strain/hour.

  17. Man-made mineral fibres in homes caused by thermal insulation

    NASA Astrophysics Data System (ADS)

    Van Der Wal, J. F.; Ebens, R.; Tempelman, J.

    In a pilot study the concentration levels of man-made mineral fibres in homes were investigated during a thermal insulation procedure in which glass or rock fibres were blown into the cavity wall. The concentration in the rooms during the insulation procedure varied between 5 × 10 -3 and 25 × 10 -3 lightmicroscopically detectable fibres cm -3, with peaks up to 65 × 10 -3 fibres cm -3. The next day the concentration had been decreased to 10 -3-10 × 10 -3 fibres cm -3. The concentration of the electronmicroscopically detectable fibres during the insulation varied between 50 × 10 -3 and 400 × 10 -3 fibres cm -3. The next day the concentration in some houses was still above the level usually found in the ambient air in The Netherlands. It is likely that good ventilation during the next day would bring the indoor concentration to the outdoor level.

  18. Analysis and Sizing for Transient Thermal Heating of Insulated Aerospace Vehicle Structures

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    2012-01-01

    An analytical solution was derived for the transient response of an insulated structure subjected to a simplified heat pulse. The solution is solely a function of two nondimensional parameters. Simpler functions of these two parameters were developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective thermal properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Equations were also developed for the minimum mass required to maintain the inner, unheated surface below a specified temperature. In the course of the derivation, two figures of merit were identified. Required insulation masses calculated using the approximate equation were shown to typically agree with finite element results within 10%-20% over the relevant range of parameters studied.

  19. Corrections for Thermal Expansion in Thermal Conductivity Measurement of Insulations Using the High-Temperature Guarded Hot-Plate Method

    NASA Astrophysics Data System (ADS)

    Wu, Jiyu; Morrell, Roger

    2012-02-01

    The anticipation of recently published European product standards for industrial thermal insulation has driven improvements in high-temperature thermal conductivity measurements in an attempt to obtain overall measurement uncertainties better than 5 % ( k = 2). The two measurement issues that are focused on in this article are the effect of thermal expansion on in situ thickness measurement and on determining the metering area at high temperatures. When implementing in situ thickness measurements, it is vital to correct the thermal expansion of components in a high-temperature guarded hot plate (HTGHP). For example, in the NPL HTGHP this could cause 3.2 % measurement error for a 50 mm thick specimen at 800 °C. The thermal expansion data for nickel 201 measured by NPL are presented, and the effect of this on the metering area of NPL's heater plate (nickel 201) is discussed.

  20. Bio-susceptibility of materials and thermal insulation systems used for historical buildings

    NASA Astrophysics Data System (ADS)

    Sterflinger, Katja; Ettenauer, Joerg; Pinar, Guadalupe

    2013-04-01

    In historical buildings of Northern countries high levels of energy are necessary to reach comfortable temperatures especially during the cold season. For this reason historical buildings are now also included in country specific regulations and ordinances to enhance the "energy - efficiency". Since an exterior insulation - as it is commonly used for modern architecture - is incompatible with monument protection, several indoor insulation systems based on historical and ecological materials, are on the market that should improve the thermic performance of a historical building. However, using organic materials as cellulose, loam, weed or wood, bears the risk of fungal growth and thus may lead to health problems in indoor environments. For this reason 5 different ecological indoor insulations systems were tested for their bio-susceptibility against various fungi both under natural conditions - after 2 years of installation in an historical building - and under laboratory conditions with high levels of relative humidity. Fungal growth was evaluated by classical isolation and cultivation as well as by molecular methods. The materials turned out to have a quite different susceptibility towards fungal contamination. Whereas insulations made of bloated Perlite (plaster and board) did not show any fungal growth after 2 years of exposition, the historical insulation made of loam and weed had high cell counts of various fungi. In laboratory experiments wooden softboard represented the best environment for fungal growth. As a result from this study, plaster and board made of bloated Perlite are presented as being the most appropriate materials for thermal insulation at least from the microbiological and hygienic point of view. For future investigations and for the monitoring of fungi in insulation and other building materials we suggest a molecular biology approach with a common protocol for quantitative DNA-extraction and amplification.

  1. ONE-DIMENSIONAL NUMERICAL ANALYSIS OF THE TRANSIENT THERMAL RESPONSE OF MULTILAYER INSULATIVE SYSTEMS

    NASA Technical Reports Server (NTRS)

    Pittman, C. M.

    1994-01-01

    This program performs a one-dimensional numerical analysis of the transient thermal response of multi-layer insulative systems. The analysis can determine the temperature distribution through a system consisting of from one to four layers, one of which can be an air gap. Concentrated heat sinks at any interface can be included. The computer program based on the analysis will determine the thickness of a specified layer that will satisfy a temperature limit criterion at any point in the insulative system. The program will also automatically calculate the thickness at several points on a system and determine the total system mass. This program was developed as a tool for designing thermal protection systems for high-speed aerospace vehicles but could be adapted to many areas of industry involved in thermal insulation systems. In this package, the equations describing the transient thermal response of a system are developed. The governing differential equation for each layer and boundary condition are put in finite-difference form using a Taylor's series expansion. These equations yield an essentially tridiagonal matrix of unknown temperatures. A procedure based on Gauss' elimination method is used to solve the matrix. This program is written in FORTRAN IV for the CDC RUN compiler and has been implemented on a CDC 6000 series machine operating under SCOPE 3.0. This program requires a minimum of 44K (octal) of 60 bit words of memory.

  2. Thermal characteristics of a meta-aramid and cellulose insulated transformer at loads beyond nameplate

    SciTech Connect

    Zodeh, O.M.; Whearty, R.J.

    1997-01-01

    Advancement in meta-aramic--a synthetic, aromatic polyamide in which the phenyl molecules are connected in the meta orientation--paper and pressboard technology has lead to production of a high temperature insulation system that can be used in transformers, replacing cellulose materials in the windings, thereby eliminating the cellulose temperature limitation. A medium-power mineral oil-immersed transformer was constructed with a hybrid insulation system comprised of meta-aramid paper and pressboard insulated windings and cellulose bulk insulation. Fiber-optic temperature sensors were installed for direct reading of oil and conductor temperatures at key points throughout the transformer. The transformer was tested and thermal constants were determined in accordance with PC57.119/D12 for both ONAN and ONAF cooling modes at load levels up to 137% of the maximum nameplate rating of an otherwise identically designed all cellulose insulated unit. Temperatures predicted by equations in the ANSI/IEEE C57.92 Loading Guide were compared with measured values. Anomalies in the data are investigated and explanations offered.

  3. High-performance, non-CFC-based thermal insulation: Gas filled panels

    SciTech Connect

    Griffith, B.T.; Arasteh, D.; Selkowitz, S.

    1992-04-01

    Because of the forthcoming phase-out of CFCs and to comply with the more stringent building and appliance energy-use standards, researchers in industry and in the public sector are pursuing the development of non-CFC-based, high-performance insulation materials. This report describes the results of research and development of one alternative insulation material: highly insulating GFPs. GFPs insulate in two ways: by using a gas barrier envelope to encapsulate a low-thermal-conductivity gas or gas mixture (at atmospheric pressure), and by using low-emissivity baffles to effectively eliminate convective and radiative heat transfer. This approach has been used successfully to produce superinsulated windows. Unlike foams or fibrous insulations, GFPs are not a homogeneous material but rather an assembly of specialized components. The wide range of potential applications of GFPs (appliances, manufactured housing, site-built buildings, refrigerated transport, and so on) leads to several alternative embodiments. While the materials used for prototype GFPs are commercially available, further development of components may be necessary for commercial products. With the exception of a description of the panels that were independently tested, specific information concerning panel designs and materials is omitted for patent reasons; this material is the subject of a patent application by Lawrence Berkeley Laboratory.

  4. Photoacoustic emission from Au nanoparticles arrayed on thermal insulation layer.

    PubMed

    Namura, Kyoko; Suzuki, Motofumi; Nakajima, Kaoru; Kimura, Kenji

    2013-04-01

    Efficient photoacoustic emission from Au nanoparticles on a porous SiO(2) layer was investigated experimentally and theoretically. The Au nanoparticle arrays/porous SiO(2)/SiO(2)/Ag mirror sandwiches, namely, local plasmon resonators, were prepared by dynamic oblique deposition (DOD). Photoacoustic measurements were performed on the local plasmon resonators, whose optical absorption was varied from 0.03 (3%) to 0.95 by varying the thickness of the dielectric SiO(2) layer. The sample with high absorption (0.95) emitted a sound that was eight times stronger than that emitted by graphite (0.94) and three times stronger than that emitted by the sample without the porous SiO(2) layer (0.93). The contribution of the porous SiO(2) layer to the efficient photoacoustic emission was analyzed by means of a numerical method based on a one-dimensional heat transfer model. The result suggested that the low thermal conductivity of the underlying porous layer reduces the amount of heat escaping from the substrate and contributes to the efficient photoacoustic emission from Au nanoparticle arrays. Because both the thermal conductivity and the spatial distribution of the heat generation can be controlled by DOD, the local plasmon resonators produced by DOD are suitable for the spatio-temporal modulation of the local temperature. PMID:23571958

  5. The empirical evaluation of thermal conduction coefficient of some liquid composite heat insulating materials

    NASA Astrophysics Data System (ADS)

    Anisimov, M. V.; Rekunov, V. S.; Babuta, M. N.; Bach Lien, Nguyen Thi Hong

    2016-02-01

    We experimentally determined the coefficients of thermal conductivity of some ultra thin liquid composite heat insulating coatings, for sample #1 λ = 0.086 W/(m·°C), for sample #2 λ = 0.091 W/(m·°C). We performed the measurement error calculation. The actual thermal conduction coefficient of the studied samples was higher than the declared one. The manufactures of liquid coatings might have used some "ideal" conditions when defining heat conductivity in the laboratory or the coefficient was obtained by means of theoretical solution of heat conduction problem in liquid composite insulating media. However, liquid insulating coatings are of great interest to builders, because they allow to warm objects of complex geometric shapes (valve chambers, complex assemblies, etc.), which makes them virtually irreplaceable. The proper accounting of heating qualities of paints will allow to avoid heat loss increase above the specified limits in insulated pipes with heat transfer materials or building structures, as well as protect them from possible thawing in the period of subzero weather.

  6. Thermal Performance Testing of Cryogenic Multilayer Insulation with Silk Net Spacers

    NASA Astrophysics Data System (ADS)

    Johnson, W. L.; Frank, D. J.; Nast, T. C.; Fesmire, J. E.

    2015-12-01

    Early comprehensive testing of cryogenic multilayer insulation focused on the use of silk netting as a spacer material. Silk netting was used for multiple test campaigns that were designed to provide baseline thermal performance estimates for cryogenic insulation systems. As more focus was put on larger systems, the cost of silk netting became a deterrent and most aerospace insulation firms were using Dacron (or polyester) netting spacers by the early 1970s. In the midst of the switch away from silk netting there was no attempt to understand the difference between silk and polyester netting, though it was widely believed that the silk netting provided slightly better performance. Without any better reference for thermal performance data, the silk netting performance correlations continued to be used. In order to attempt to quantify the difference between the silk netting and polyester netting, a brief test program was developed. The silk netting material was obtained from Lockheed Martin and was tested on the Cryostat-100 instrument in three different configurations, 20 layers with both single and double netting and 10 layers with single netting only. The data show agreement within 15 - 30% with the historical silk netting based correlations and show a substantial performance improvement when compared to previous testing performed using polyester netting and aluminum foil/fiberglass paper multilayer insulation. Additionally, the data further reinforce a recently observed trend that the heat flux is not directly proportional to the number of layers installed on a system.

  7. Validation on the thermal effect of roof with the spraying and green plants in an insulated building

    SciTech Connect

    Zhou, Nan; Gao, Weijun; Nishida, Masaru; Ojima, Toshio

    2004-03-20

    In recent years, roof-spraying and rooftop lawns has proved effective on roofs with poor thermal insulation. However, roofs of most buildings have insulating material to provide thermal insulation during the winter. The effects of such a practice have not previously been quantified. In this study, the authors conducted measurements of an insulated building to quantify the thermal effects of roof-spraying and rooftop lawns. Roof-spraying did not significantly reduce cooling loads, and required significant amounts of water. The conclusion is that roof spraying is not suitable for buildings with well-insulated roofs. Rooftop lawns, however, significantly stabilized the indoor temperature while additionally helping to mitigate the heat island phenomenon.

  8. Physicochemical characterization of the thermal aging of insulating paper in power transformers

    SciTech Connect

    Lessard, M.C.; Van Nifterik, L.; Masse, M.; Penneau, J.F.; Grob, R.

    1996-12-31

    Paper is a low-cost base material with outstanding mechanical and electrical properties, which is why it is still a key element in the insulation of electrical apparatus. Under the effect of a variety of factors including temperature, paper can substantially lose its properties, thus jeopardizing the service life of costly equipment. To remedy this situation, new so-called thermally upgraded papers are being made by certain manufacturers. A study carried out jointly by Hydro-Quebec, Electricite de France and the Ecole Nationale Superieure de Chimie de Toulouse has allowed researchers to qualify the thermal resistance of three different types of thermostable paper. These papers have been selected as being representative of what is available on the market today. The paper samples were subjected to a thermal aging test in the presence of mineral oil to represent normal conditions of operation (150 C). The thermal degradation of the paper insulation is characterized by various physicochemical methods including measurement of the degree of polymerization, determination of 2-furfural in mineral oil by HPLC as well as determination of various sugars (monosaccharides, polysaccharides and anhydrosugars) in the paper using ion chromatography. This last method allows the authors to verify the formation of cellobiose, which is the real repeat unit of cellulose, as well as that of levoglucosan, which is an anhydrosugar and a precursor of 2-furfural. The evolution of all of these parameters, measured as a function of time, has allowed them to compare the thermal resistance of various insulating papers. The results of this study seem to show that, compared to traditional kraft paper, certain paper types are more susceptible to being thermally upgraded than others. This study also allowed the authors to demonstrate that the use of an inhibitor in mineral oil (DBPC) does not seem to influence the thermal degradation of these papers.

  9. Thermal insulation of the intertidal zone by the ice foot

    NASA Astrophysics Data System (ADS)

    Scrosati, Ricardo; Eckersley, Lindsay K.

    2007-11-01

    Few studies have looked at the ecological significance of the ice foot in intertidal habitats. During the 2007 winter, we quantified the hourly variation of temperature at the intertidal zone and at the upper, dry coast on the southern Gulf of St. Lawrence (Nova Scotia, Canada) using submersible data loggers. While air temperature dropped to - 20 °C at the peak of the winter, intertidal temperature was never below - 7 °C during the winter. In fact, for almost two months when the ice foot was stable, temperature ranged only between - 2.4 °C and - 1.1 °C at the intertidal zone. The intertidal values are higher than published values of lethal temperature for cold-water intertidal invertebrates and seaweeds. Thus, the ice foot may prevent these organisms from experiencing lethal levels of thermal stress, contributing to their long-term persistence in these environmentally stressful habitats.

  10. An Analytical Solution for Transient Thermal Response of an Insulated Structure

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    2012-01-01

    An analytical solution was derived for the transient response of an insulated aerospace vehicle structure subjected to a simplified heat pulse. This simplified problem approximates the thermal response of a thermal protection system of an atmospheric entry vehicle. The exact analytical solution is solely a function of two non-dimensional parameters. A simpler function of these two parameters was developed to approximate the maximum structural temperature over a wide range of parameter values. Techniques were developed to choose constant, effective properties to represent the relevant temperature and pressure-dependent properties for the insulator and structure. A technique was also developed to map a time-varying surface temperature history to an equivalent square heat pulse. Using these techniques, the maximum structural temperature rise was calculated using the analytical solutions and shown to typically agree with finite element simulations within 10 to 20 percent over the relevant range of parameters studied.

  11. APPLICATION OF POLYURETHANE FOAM FOR IMPACT ABSORPTION AND THERMAL INSULATION FOR GENERAL PURPOSE RADIOACTIVE MATERIALS PACKAGINGS

    SciTech Connect

    Smith, A; Glenn Abramczyk, G; Paul Blanton, P; Steve Bellamy, S; William Daugherty, W; Sharon Williamson, S

    2009-02-18

    Polyurethane foam has been employed in impact limiters for large radioactive materials packagings since the early 1980's. Its consistent crush response, controllable structural properties and excellent thermal insulating characteristics have made it attractive as replacement for the widely used cane fiberboard for smaller, drum size packagings. Accordingly, polyurethane foam was chosen for the overpack material for the 9977 and 9978 packagings. The study reported here was undertaken to provide data to support the analyses performed as part of the development of the 9977 and 9978, and compared property values reported in the literature with published property values and test results for foam specimens taken from a prototype 9977 packaging. The study confirmed that, polyurethane foam behaves in a predictable and consistent manner and fully satisfies the functional requirements for impact absorption and thermal insulation.

  12. Machine-able Yttria Stabilized Zirconia Composites for Thermal Insulation in Nuclear Reactors

    NASA Astrophysics Data System (ADS)

    Lo, J.; Zhang, R.; Santos, R.

    2016-02-01

    Ceramics are a promising insulating material for high temperature environment. To qualify for in-core use in nuclear reactors, there are many other materials requirements to be met, such as neutron irradiation resistance, corrosion resistance, low thermal conductivity, high coefficient of thermal expansion, high strength, high fracture toughness, ease of fabricability, etc. And among the promising ceramics meeting most of the requirements, with the exception of fabricability, is yttria-stabilized zirconia (YSZ). Like all ceramics, YSZ is hard, brittle and difficult to machine. At CanmetMATERIALS, YSZ-based composites for in-core insulation that are machine-able and capable of being formed into complex shapes have been developed. In this paper, the focus is geared towards the fabrication and property evaluation of such composites. In addition, the machinability aspect of the YSZ composites was addressed with a demonstration of a machined component.

  13. Application of Nanotechnology-Based Thermal Insulation Materials in Building Construction

    NASA Astrophysics Data System (ADS)

    Bozsaky, David

    2016-03-01

    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.

  14. Thermal Transmittance and the Embodied Energy of Timber Frame Lightweight Walls Insulated with Straw and Reed

    NASA Astrophysics Data System (ADS)

    Miljan, M.; Miljan, J.

    2015-11-01

    Sustainable energy use has become topical in the whole world. Energy gives us comfort we are used to. EU and national regulations determine energy efficiency of the buildings. This is one side of the problem - energy efficiency of houses during exploitation. But the other side is primary energy content of used materials and more rational use of resources during the whole life cycle of a building. The latter value constitutes about 8 - 20% from the whole energy content. Calculations of energy efficiency of materials lead us to energy efficiency of insulation materials and to comparison of natural and industrial materials taking into account their thermal conductivity as well as their primary energy content. Case study of the test house (built in 2012) insulated with straw bales gave the result that thermal transmittance of investigated straw bale walls was according to the minimum energy efficiency requirements set in Estonia U = 0.12 - 0.22 W/m2K (for walls).

  15. A thermal porosimetry method to estimate pore size distribution in highly porous insulating materials.

    PubMed

    Félix, V; Jannot, Y; Degiovanni, A

    2012-05-01

    Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10(-1) to 10(5) Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent. PMID:22667640

  16. A thermal porosimetry method to estimate pore size distribution in highly porous insulating materials

    NASA Astrophysics Data System (ADS)

    Félix, V.; Jannot, Y.; Degiovanni, A.

    2012-05-01

    Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10-1 to 105 Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent.

  17. A thermal porosimetry method to estimate pore size distribution in highly porous insulating materials

    SciTech Connect

    Felix, V.; Jannot, Y.; Degiovanni, A.

    2012-05-15

    Standard pore size determination methods such as mercury porosimetry, nitrogen sorption, microscopy, or x-ray tomography are not always applicable to highly porous, low density, and thus very fragile materials. For this kind of materials, a method based on thermal characterization is proposed. Indeed, the thermal conductivity of a highly porous and insulating medium is significantly dependent on the thermal conductivity of the interstitial gas that depends on both gas pressure and size of the considered pore (Knudsen effect). It is also possible to link the pore size with the thermal conductivity of the medium. Thermal conductivity measurements are realized on specimens placed in an enclosure where the air pressure is successively set to different values varying from 10{sup -1} to 10{sup 5} Pa. Knowing the global porosity ratio, an effective thermal conductivity model for a two-phase air-solid material based on a combined serial-parallel model is established. Pore size distribution can be identified by minimizing the sum of the quadratic differences between measured values and modeled ones. The results of the estimation process are the volume fractions of the chosen ranges of pore size. In order to validate the method, measurements done on insulating materials are presented. The results are discussed and show that pore size distribution estimated by the proposed method is coherent.

  18. High Heat Insulating Thermal Barrier Coating Designed with Large Two-Dimensional Inter-lamellar Pores

    NASA Astrophysics Data System (ADS)

    Liu, Tao; Zhang, Shan-Lin; Luo, Xiao-Tao; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2016-01-01

    Atmospheric plasma-sprayed ceramic coatings with a lamellar structure exhibit low thermal conductivity. However, high-temperature exposure causes sintering, which heals inter-lamellar two-dimensional (2D) pores and intra-splat pores. Such sintering effect increases the thermal conductivity of the coatings and consequently reduces the thermal insulation ability of TBCs. In this study, inter-lamellar 2D pores with a large opening width were introduced into the La2Zr2O7 (LZO) coating through the spraying of a LZO-SrO coating and the removal of the SrO splats in water. Then, the conventional LZO coating and the porous LZO coating were subjected to high-temperature exposure at 1300 °C, for different durations. It was found that the 2D pores resulting from SrO splats present little healing during high-temperature exposure, while the conventional 2D inter-lamellar pores with a small opening width heal rapidly. Thus, the thermal conductivity of the conventional LZO coating increased rapidly, while the unhealed 2D pores in the highly porous LZO coating contributed to the coating low thermal conductivity. The present results indicated that a high heat insulating thermal barrier coating with high stability can be fabricated though the introduction of inter-lamellar 2D pores with large opening width.

  19. Introduction to the adhesive bonding session. [foam system for attaching thermal insulation on space shuttle

    NASA Technical Reports Server (NTRS)

    Mccarty, J. E.

    1972-01-01

    Space shuttle unique requirements call for the development of a specific adhesive system to reliable attach reusable surface insulation. A low density foam system has been developed that provides strain isolation from the support structure and remains structurally stable in space shuttle thermal environment. Surface preparation and its stabilization by an adhesive primer system are the most important factors in preventing corrosion from reducing the reliability and durability of the adhesive bonding component.

  20. Thermal performance of multilayer insulation; Part 1, Derivation of a prediction-based heat-flux equation

    SciTech Connect

    Amano, Toshiyuki

    1994-09-01

    How to reduce the heat loss at cryogenic temperatures in superconducting magnets used for MRI (Magnetic Resonance Imaging), magnetically levitated trains, nuclear fusion, etc., is an important subject. The topic is important in providing a superconducting magnet with high-performance thermal insulation. A prediction-based equation for heat flux through a multilayer insulator was derived from comparison of experimental results between room temperature and liquid-nitrogen temperature. The employed multilayer insulator was a laminated material with a polyester net inserted between aluminized Mylar films. The prediction equation consists of one thermal-radiation and two thermal-conduction terms. The first conduction term is that of ordinary thermal-contact conductance. The second conduction term depends on the self-compression of the multilayer insulation. The predicted values resulting from the obtained coincided fairly well with measured values.

  1. Reduction in the thermal resistance (R-value) of loose-fill insulation and fiberglass batts due to compression

    SciTech Connect

    Yarbrough, D.W.; Wright, J.H.

    1981-04-01

    A method is presented for calculating the thickness reduction of loose-fill insulations and fiberglass batts that result from compressive forces exerted by additional insulation. The thickness reduction is accompanied by an increase in density and a reduction in the R value of the compressed layer. Calculations for thermal resistance of two layers of insulation are given. Information in 4 appendices includes: identification of products tested (products from 3 companies); experimental values for thickness as a function of loading; Fortran programs and output; and calculated R values for stacked insulations. (MCW)

  2. Design Considerations for Thermally Insulating Structural Sandwich Panels for Hypersonic Vehicles

    NASA Technical Reports Server (NTRS)

    Blosser, Max L.

    2016-01-01

    Simplified thermal/structural sizing equations were derived for the in-plane loading of a thermally insulating structural sandwich panel. Equations were developed for the strain in the inner and outer face sheets of a sandwich subjected to uniaxial mechanical loads and differences in face sheet temperatures. Simple equations describing situations with no viable solution were developed. Key design parameters, material properties, and design principles are identified. A numerical example illustrates using the equations for a preliminary feasibility assessment of various material combinations and an initial sizing for minimum mass of a sandwich panel.

  3. NBC boil-off calorimeter for measuring thermal conductivity of insulating materials

    NASA Technical Reports Server (NTRS)

    Dube, W. P.; Sparks, L. L.; Slifka, A. J.

    1988-01-01

    Modern temperature, pressure and flow sensors along with a high speed digital control system have been incorporated into an existing thermal conductivity apparatus (ASTM C745). The system has also been modified to include the use of liquid helium as the refrigerant, if desired. The apparatus can be used to study thermal conductivity in the temperature range from 4 K to room temperature. Preliminary results on insulating materials indicate that the system update has significantly improved the precision and operational characteristics of the apparatus. Basic principles of operation, sources of system error and the reduction of system error by application of digital control and modern sensors are discussed. Preliminary data are presented.

  4. NBC boil-off calorimeter for measuring thermal conductivity of insulating materials

    NASA Astrophysics Data System (ADS)

    Dube, W. P.; Sparks, L. L.; Slifka, A. J.

    Modern temperature, pressure and flow sensors along with a high speed digital control system have been incorporated into an existing thermal conductivity apparatus (ASTM C745). The system has also been modified to include the use of liquid helium as the refrigerant, if desired. The apparatus can be used to study thermal conductivity in the temperature range from 4 K to room temperature. Preliminary results on insulating materials indicate that the system update has significantly improved the precision and operational characteristics of the apparatus. Basic principles of operation, sources of system error and the reduction of system error by application of digital control and modern sensors are discussed. Preliminary data are presented.

  5. Method for preparing a solid phase microextraction device using aerogel

    DOEpatents

    Miller, Fred S.; Andresen, Brian D.

    2006-10-24

    A sample collection substrate of aerogel and/or xerogel materials bound to a support structure is used as a solid phase microextraction (SPME) device. The xerogels and aerogels may be organic or inorganic and doped with metals or other compounds to target specific chemical analytes. The support structure is typically formed of a glass fiber or a metal wire (stainless steel or kovar). The devices are made by applying gel solution to the support structures and drying the solution to form aerogel or xerogel. Aerogel particles may be attached to the wet layer before drying to increase sample collection surface area. These devices are robust, stable in fields of high radiation, and highly effective at collecting gas and liquid samples while maintaining superior mechanical and thermal stability during routine use. Aerogel SPME devices are advantageous for use in GC/MS analyses due to their lack of interfering background and tolerance of GC thermal cycling.

  6. Thermal Insulation Properties Research of the Composite Material "Water Glass - Graphite Microparticles"

    NASA Astrophysics Data System (ADS)

    Gostev, V. A.; Pitukhin, E. A.; Ustinov, A. S.; Shelestov, A. S.

    2016-04-01

    Research results for the composite material (CM) "water glass - graphite microparticles" with high thermal stability and thermal insulation properties are given. A composition is proposed consisting of graphite (42 % by weight), water glass Na2O(SiO2)n (50% by weight) and the hardener - sodium silicofluoride Na2SiF6 (8% by weight). Processing technology of such composition is suggested. Experimental samples of the CM with filler particles (graphite) of a few microns in size were obtained. This is confirmed by a study of samples using X-ray diffraction analysis and electron microscopy. The qualitative and quantitative phase analysis of the CM structure was done. Values of limit load causing destruction of the CM were identified. The character of the rupture surface was detected. Numerical values of the specific heat and thermal conductivity were defined. Dependence of the specific heat capacity and thermal conductivity on temperature during monotonic heating was obtained experimentally. Studies have confirmed the increased thermal insulation properties of the proposed composition. The CM with such properties can be recommended as a coating designed to reduce heat losses and resistant to high temperatures. Due to accessibility and low cost of its components the proposed material can be produced on an industrial scale.

  7. A large experimental apparatus for measuring thermal conductance of LH2 storage tank insulations

    NASA Astrophysics Data System (ADS)

    Kamiya, S.; Onishi, K.; Kawagoe, E.; Nishigaki, K.

    2000-01-01

    In the Japanese hydrogen project, WE-NET (World Energy Net Work), the conceptual design of the large mass liquid hydrogen storage systems for ground tanks and transportation, whose scales would reach to that of commercialized LNG (liquid national gas), has been studied. This study has concluded that the thermal insulation for a mass storage tank, providing the excellent thermal performance with the optimized strength, should be developed. In order to evaluate thermal conductance of various devised insulations, we have manufactured a large-scale experimental apparatus. This apparatus, which adopts a double guarded flat plate boil-off calorimeter method, can provide the thermal data needed for designing a full-scale tank. It would be possible to test various kinds of specimens with allowable dimensions: diameter 120 cm, thickness up to 30 cm. In the case of a rigid specimen contacting bottom surfaces of liquid hydrogen vessels, the good flatness of their bottom plates is desirable to reduce the thermal resistance between vessels and a specimen surface. This paper describes the abstract of the developed apparatus, its structural design and also the experimental results for verifying its structural design.

  8. Vibration Considerations for Cryogenic Tanks Using Glass Bubbles Insulation

    NASA Technical Reports Server (NTRS)

    Werlink, Rudolph J.; Fesmire, James E.; Sass, Jared P.

    2011-01-01

    The use of glass bubbles as an efficient and practical thermal insulation system has been previously demonstrated in cryogenic storage tanks. One such example is a spherical, vacuum-jacketed liquid hydrogen vessel of 218,000 liter capacity where the boiloff rate has been reduced by approximately 50 percent. Further applications may include non-stationary tanks such as mobile tankers and tanks with extreme duty cycles or exposed to significant vibration environments. Space rocket launch events and mobile tanker life cycles represent two harsh cases of mechanical vibration exposure. A number of bulk fill insulation materials including glass bubbles, perlite powders, and aerogel granules were tested for vibration effects and mechanical behavior using a custom design holding fixture subjected to random vibration on an Electrodynamic Shaker. The settling effects for mixtures of insulation materials were also investigated. The vibration test results and granular particle analysis are presented with considerations and implications for future cryogenic tank applications. A thermal performance update on field demonstration testing of a 218,000 L liquid hydrogen storage tank, retrofitted with glass bubbles, is presented. KEYWORDS: Glass bubble, perlite, aerogel, insulation, liquid hydrogen, storage tank, mobile tanker, vibration.

  9. EVALUATION OF THERMAL CONDUCTIVITY OF INSTALLED-IN-PLACE POLYURETHANE FOAM INSULATION BY EXPERIMENT AND ANALYSIS

    SciTech Connect

    Smith, A; Bruce Hardy, B; Kurt Eberl, K; Nick Gupta, N

    2007-12-05

    In the thermal analysis of the 9977 package, it was found that calculated temperatures, determined using a typical thermal analysis code, did not match those measured in the experimental apparatus. The analysis indicated that the thermal resistance of the overpack in the experimental apparatus was less than that expected, based on manufacturer's reported value of thermal conductivity. To resolve this question, the thermal conductivity of the installed foam was evaluated from the experimental results, using a simplified analysis. This study confirmed that the thermal resistance of the experimental apparatus was lower than that which would result from the manufacturer's published values for thermal conductivity of the foam insulation. The test package was sectioned to obtain samples for measurement of material properties. In the course of the destructive examination a large uninsulated region was found at the bottom of the package, which accounted for the anomalous results. Subsequent measurement of thermal conductivity confirmed the manufacturer's published values. The study provides useful insight into the use of simplified, scoping calculations for evaluation of thermal performance of packages.

  10. Thermal conductivity of spray-on foam insulations for aerospace applications

    NASA Astrophysics Data System (ADS)

    Barrios, Matt; Vanderlaan, Mark; Van Sciver, Steven

    2012-06-01

    A guarded-hot-plate apparatus [1] has been developed to measure the thermal conductivity of spray-on foam insulations (SOFI) at temperatures ranging from 30 K to 300 K. The foam tested in the present study is NCFI 24-124, a polyisocyanurate foam used on the External Tanks of the Space Shuttle. The foam was tested first in ambient pressure air, then evacuated and tested once more. These thermal conductivities were compared to the thermal conductivity taken from a sample immediately after being subjected to conditions similar to those experienced by the foam while on the launch pad at Kennedy Space Center. To mimic the conditions experienced on the launch pad, an apparatus was built to enclose one side of the foam sample in a warm, humid environment while the other side of the sample contacts a stainless steel surface held at 77 K. The thermal conductivity data obtained is also compared to data found in the literature.

  11. Characterization of vacuum-multifoil insulation for long-life thermal batteries

    SciTech Connect

    GUIDOTTI,RONALD A.; REINHARDT,FREDERICK W.; KAUN,THOMAS

    2000-04-17

    The use of vacuum multifoil (VMF) container for thermal insulation in long-life thermal batteries was investigated in a proof-of-concept demonstration. An InvenTek-designed VMF container 4.9 inches in diameter by 10 inches long was used with an internally heated aluminum block, to simulate a thermal-battery stack. The block was heated to 525 C or 600 C and allowed to cool while monitoring the temperature of the block and the external case at three locations with time. The data indicate that it should be possible to build an equivalent-sized thermal battery that should last up to six hours, which would meet the requirements for a long-life sonobuoy application.

  12. High-temperature properties of ceramic fibers and insulations for thermal protection of atmospheric entry and hypersonic cruise vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

    1988-01-01

    Multilayer insulations (MIs) which will operate in the 500 to 1000 C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described consist of ceramic fibers, insulations, and metal foils quilted together with ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of MIs and are compared to the baseline Advanced Flexible Reusable Surface Insulation currently used on the Space Shuttle Orbiter. In addition, the high temperature properties of the fibers used in these MIs are discussed. The fibers investigated included silica and three types of aluminoborosilicate (ABS). Static tension tests were performed at temperatures up to 1200 C and the ultimate strain, tensile strength, and tensile modulus of single fibers were determined.

  13. High temperature properties of ceramic fibers and insulations for thermal protection of atmospheric entry and hypersonic cruise vehicles

    NASA Technical Reports Server (NTRS)

    Kourtides, Demetrius A.; Pitts, William C.; Araujo, Myrian; Zimmerman, R. S.

    1988-01-01

    Multilayer insulations (MIs) which will operate in the 500 to 1000 C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described consist of ceramic fibers, insulations, and metal foils quilted together with ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of MIs and are compared to the baseline Advanced Flexible Reusable Surface Insulation currently used on the Space Shuttle Orbiter. In addition, the high temperature properties of the fibers used in these MIs are discussed. The fibers investigated included silica and three types of aluminoborosilicate (ABS). Static tension tests were performed at temperatures up to 1200 C and the ultimate strain, tensile strength, and tensile modulus of single fibers were determined.

  14. High-temperature properties of ceramic fibers and insulations for thermal protection of atmospheric entry and hypersonic cruise vehicles

    SciTech Connect

    Kourtides, D.A.; Pitts, W.C.; Araujo, M.; Zimmerman, R.S.

    1988-02-01

    Multilayer insulations (MIs) which will operate in the 500 to 1000 C temperature range are being considered for possible applications on aerospace vehicles subject to convective and radiative heating during atmospheric entry. The insulations described consist of ceramic fibers, insulations, and metal foils quilted together with ceramic thread. As these types of insulations have highly anisotropic properties, the total heat transfer characteristics must be determined. Data are presented on the thermal diffusivity and thermal conductivity of four types of MIs and are compared to the baseline Advanced Flexible Reusable Surface Insulation currently used on the Space Shuttle Orbiter. In addition, the high temperature properties of the fibers used in these MIs are discussed. The fibers investigated included silica and three types of aluminoborosilicate (ABS). Static tension tests were performed at temperatures up to 1200 C and the ultimate strain, tensile strength, and tensile modulus of single fibers were determined.

  15. Method of casting aerogels

    DOEpatents

    Poco, J.F.

    1993-09-07

    The invention describes a method for making monolithic castings of transparent silica aerogel with densities in the range from 0.001 g/cm[sup 3] to 0.6 g/cm[sup 3]. Various shapes of aerogels are cast in flexible polymer molds which facilitate removal and eliminate irregular surfaces. Mold dimensions are preselected to account for shrinkage of aerogel which occurs during the drying step of supercritical extraction of solvent. 2 figures.

  16. Multiscale Computer Simulation of Tensile and Compressive Strain in Polymer- Coated Silica Aerogels

    NASA Technical Reports Server (NTRS)

    Good, Brian

    2009-01-01

    While the low thermal conductivities of silica aerogels have made them of interest to the aerospace community as lightweight thermal insulation, the application of conformal polymer coatings to these gels increases their strength significantly, making them potentially useful as structural materials as well. In this work we perform multiscale computer simulations to investigate the tensile and compressive strain behavior of silica and polymer-coated silica aerogels. Aerogels are made up of clusters of interconnected particles of amorphous silica of less than bulk density. We simulate gel nanostructure using a Diffusion Limited Cluster Aggregation (DLCA) procedure, which produces aggregates that exhibit fractal dimensions similar to those observed in real aerogels. We have previously found that model gels obtained via DLCA exhibited stress-strain curves characteristic of the experimentally observed brittle failure. However, the strain energetics near the expected point of failure were not consistent with such failure. This shortcoming may be due to the fact that the DLCA process produces model gels that are lacking in closed-loop substructures, compared with real gels. Our model gels therefore contain an excess of dangling strands, which tend to unravel under tensile strain, producing non-brittle failure. To address this problem, we have incorporated a modification to the DLCA algorithm that specifically produces closed loops in the model gels. We obtain the strain energetics of interparticle connections via atomistic molecular statics, and abstract the collective energy of the atomic bonds into a Morse potential scaled to describe gel particle interactions. Polymer coatings are similarly described. We apply repeated small uniaxial strains to DLCA clusters, and allow relaxation of the center eighty percent of the cluster between strains. The simulations produce energetics and stress-strain curves for looped and nonlooped clusters, for a variety of densities and

  17. Detection of defects in foam thermal insulation using lateral migration backscatter x-ray radiography

    NASA Astrophysics Data System (ADS)

    Dugan, Edward T.; Jacobs, Alan M.; Shedlock, Dan; Ekdahl, Dan

    2004-10-01

    A new Compton x-ray backscatter imaging technique called lateral migration radiography (LMR) has been successfully applied to the detection of voids and delaminations in the foam thermal insulation used on the shuttle external tank. LMR employs detection of selected scatter field velocity components, by using specially designed detectors and detector collimators, to achieve high image contrast. LMR is based on image contrast generated by migration of probe x-ray radiation in directions transverse to the illumination radiation beam. Because LMR is sensitive to electron density variations in these directions, thin, but large density variations, such as cracks and delaminations, generate signal-to-background ratios sufficient to produce images of features which are not even detectable in the usually interrogated thin dimension. The examined foam thermal insulation test panels consist of aluminum plates onto which the sprayed-on foam insulation (SOFI) is applied. Some of the test panels include structural features bolted to the base plate. The SOFI was layed down over the base plate and structure with a thickness varying from a few tens of mm up to a few hundred mm. The test panels included voids and simulated delaminations in the SOFI ranging in cross-sectional size from 6 x 6 mm to 50 x 50 mm. High quality images were acquired using pixels of 2 to 3 mm and irradiation times as low as 0.05 s per pixel.

  18. Thermal performance of gaseous-helium-purged tank-mounted multilayer insulation system during ground-hold and space-hold thermal cycling and exposure to water vapor

    NASA Technical Reports Server (NTRS)

    Sumner, I. E.

    1978-01-01

    An experimental investigation was conducted to determine (1) the ground-hold and space-hold thermal performance of a multilayer insulation (MLI) system mounted on a spherical, liquid-hydrogen propellant tank and (2) the degradation to the space-hold thermal performance of the insulation system that resulted from both thermal cycling and exposure to moisture. The propellant tank had a diameter of 1.39 meters (4.57ft). The MLI consisted of two blankets of insulation; each blanket contained 15 double-aluminized Mylar radiation shields separated by double silk net spacers. Nineteen tests simulating basic cryogenic spacecraft thermal (environmental) conditions were conducted. These tests typically included initial helium purge, liquid-hydrogen fill and ground-hold, ascent, space-hold, and repressurization. No significant degradation of the space-hold thermal performance due to thermal cycling was noted.

  19. Acoustic and Thermal Testing of an Integrated Multilayer Insulation and Broad Area Cooling Shield System

    NASA Technical Reports Server (NTRS)

    Wood, Jessica J.; Foster, Lee W.

    2013-01-01

    A Multilayer Insulation (MLI) and Broad Area Cooling (BAC) shield thermal control system shows promise for long-duration storage of cryogenic propellant. The NASA Cryogenic Propellant Storage and Transfer (CPST) project is investigating the thermal and structural performance of this tank-applied integrated system. The MLI/BAC Shield Acoustic and Thermal Test was performed to evaluate the MLI/BAC shield's structural performance by subjecting it to worst-case launch acoustic loads. Identical thermal tests using Liquid Nitrogen (LN2) were performed before and after the acoustic test. The data from these tests was compared to determine if any degradation occurred in the thermal performance of the system as a result of exposure to the acoustic loads. The thermal test series consisted of two primary components: a passive boil-off test to evaluate the MLI performance and an active cooling test to evaluate the integrated MLI/BAC shield system with chilled vapor circulating through the BAC shield tubes. The acoustic test used loads closely matching the worst-case envelope of all launch vehicles currently under consideration for CPST. Acoustic test results yielded reasonable responses for the given load. The thermal test matrix was completed prior to the acoustic test and successfully repeated after the acoustic test. Data was compared and yielded near identical results, indicating that the MLI/BAC shield configuration tested in this series is an option for structurally implementing this thermal control system concept.

  20. Method to produce alumina aerogels having porosities greater than 80 percent

    SciTech Connect

    Poco, John F.; Hrubesh, Lawrence W.

    2003-09-16

    A two-step method for producing monolithic alumina aerogels having porosities of greater than 80 percent. Very strong, very low density alumina aerogel monoliths are prepared using the two-step sol-gel process. The method of preparing pure alumina aerogel modifies the prior known sol method by combining the use of substoichiometric water for hydrolysis, the use of acetic acid to control hydrolysis/condensation, and high temperature supercritical drying, all of which contribute to the formation of a polycrystalline aerogel microstructure. This structure provides exceptional mechanical properties of the alumina aerogel, as well as enhanced thermal resistance and high temperature stability.

  1. Densely-tiled metal-insulator-metal metamaterial resonators with quasi- monochromatic thermal emission.

    PubMed

    Ito, Kota; Toshiyoshi, Hiroshi; Iizuka, Hideo

    2016-06-13

    Metal-insulator-metal metamaterial thermal emitters strongly radiate at multiple resonant wavelengths. The fundamental mode, whose wavelength is the longest among resonances, is generally utilized for selective emission. In this paper, we show that parasitic modes at shorter wavelengths are suppressed by newly employed densely-tiled resonators, and that the suppression enables quasi-monochromatic thermal emission. The second-order harmonics, which is excited at half the fundamental wavelength in conventional emitters, shifts toward shorter wavelength. The blue-shift reduces the amplitude of the second-order emission by taking a distance from the Wien wavelength. Other parasitic modes are eliminated by the small spacing between resonators. The densely-tiled resonators are fabricated, and the measured emission spectra agree well with numerical simulations. The methodology presented here for the suppression of parasitic modes adds flexibility to metamaterial thermal emitters. PMID:27410299

  2. Interfacial thermal conductance across metal-insulator/semiconductor interfaces due to surface states

    NASA Astrophysics Data System (ADS)

    Lu, Tingyu; Zhou, Jun; Nakayama, Tsuneyoshi; Yang, Ronggui; Li, Baowen

    2016-02-01

    We point out that the effective channel for the interfacial thermal conductance, the inverse of Kapitza resistance, of metal-insulator/semiconductor interfaces is governed by the electron-phonon interaction mediated by the surface states allowed in a thin region near the interface. Our detailed calculations demonstrate that the interfacial thermal conductance across Pb/Pt/Al/Au-diamond interfaces are only slightly different among these metals, and reproduce well the experimental results of the interfacial thermal conductance across metal-diamond interfaces observed by Stoner et al. [Phys. Rev. Lett. 68, 1563 (1992), 10.1103/PhysRevLett.68.1563] and most recently by Hohensee et al. [Nat. Commun. 6, 6578 (2015), 10.1038/ncomms7578].

  3. Cellulose aerogels from aqueous alkali hydroxide-urea solution.

    PubMed

    Cai, Jie; Kimura, Satoshi; Wada, Masahisa; Kuga, Shigenori; Zhang, Lina

    2008-01-01

    Highly porous and strong cellulose aerogels were prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution, followed by drying with supercritical CO2. Their morphology, pore structure, and physical properties were characterized by scanning and transmission electron microscopy, X-ray diffraction, nitrogen adsorption measurements, UV/Vis spectrometry, and tensile tests. The cellulose hydrogel was composed of interconnected about 20 nm wide. By using supercritical CO2 drying, the network structure in the hydrogel was well preserved in the aerogel. The results are preliminary but demonstrate the ability of this method to give cellulose aerogels of large surface areas (400-500 m2 g(-1)) which may be useful as adsorbents, heat/sound insulators, filters, catalyst supports, or carbon aerogel precursors. PMID:18605678

  4. Method of manufacturing aerogel composites

    DOEpatents

    Cao, Wanqing; Hunt, Arlon Jason

    1999-01-01

    Disclosed herewith is a process of forming an aerogel composite which comprises introducing a gaseous material into a formed aerogel monolith or powder, and causing decomposition of said gaseous material in said aerogel in amounts sufficient to cause deposition of the decomposition products of the gas on the surfaces of the pores of the said aerogel.

  5. Method of manufacturing aerogel composites

    DOEpatents

    Cao, W.; Hunt, A.J.

    1999-03-09

    Disclosed herewith is a process of forming an aerogel composite which comprises introducing a gaseous material into a formed aerogel monolith or powder, and causing decomposition of said gaseous material in said aerogel in amounts sufficient to cause deposition of the decomposition products of the gas on the surfaces of the pores of the said aerogel.

  6. Aerogel-clad optical fiber

    DOEpatents

    Sprehn, Gregory A.; Hrubesh, Lawrence W.; Poco, John F.; Sandler, Pamela H.

    1997-01-01

    An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency.

  7. Aerogel-clad optical fiber

    DOEpatents

    Sprehn, G.A.; Hrubesh, L.W.; Poco, J.F.; Sandler, P.H.

    1997-11-04

    An optical fiber is surrounded by an aerogel cladding. For a low density aerogel, the index of refraction of the aerogel is close to that of air, which provides a high numerical aperture to the optical fiber. Due to the high numerical aperture, the aerogel clad optical fiber has improved light collection efficiency. 4 figs.

  8. Optimization by means of an analytical heat transfer model of a thermal insulation for CSP applications based on radiative shields

    NASA Astrophysics Data System (ADS)

    Gaetano, A.; Roncolato, J.; Montorfano, D.; Barbato, M. C.; Ambrosetti, G.; Pedretti, A.

    2016-05-01

    The employment of new gaseous heat transfer fluids as air or CO2, which are cheaper and environmentally friendly, is drawing more and more attention within the field of Concentrated Solar Power applications. However, despite the advantages, their use requires receivers with a larger heat transfer area and flow cross section with a consequent greater volume of thermal insulation. Solid thermal insulations currently used present high thermal inertia which is energetically penalizing during the daily transient phases faced by the main plant components (e.g. receivers). With the aim of overcoming this drawback a thermal insulation based on radiative shields is presented in this study. Starting from an initial layout comprising a solid thermal insulation layer, the geometry was optimized avoiding the use of the solid insulation keeping performance and fulfilling the geometrical constraints. An analytical Matlab model was implemented to assess the system thermal behavior in terms of heat loss taking into account conductive, convective and radiative contributions. Accurate 2D Computational Fluid Dynamics (CFD) simulations were run to validate the Matlab model which was then used to select the most promising among three new different designs.

  9. Microthruster with integrated platinum thin film resistance temperature detector (RTD), heater, and thermal insulation

    NASA Astrophysics Data System (ADS)

    Miyakawa, N.; Legner, W.; Ziemann, T.; Telitschkin, D.; Fecht, H.-J.; Friedberger, A.

    2011-06-01

    We have fabricated microthruster chip pairs - one chip with microthruster structures such as injection capillaries, combustion chamber and nozzle, the other chip with platinum thin film devices such as resistance temperature detectors (RTDs) and a heater. The platinum thin film was sputtered on thermally oxidized silicon wafers WITHOUT adhesion layer. The effects of anneal up to 1050°C on the surface morphology of platinum thin films with varied geometry as well as with / without PECVD-SiO2 coating were investigated in air and N2 and results will also be presented. Electrical characterization of sensors was carried out in a furnace tube in which the sensors' temperature was varied between room temperature and 1000°C with a ramp of +/-5Kmin-1 in air and N2. The experiments showed that the temperature-resistance characteristics of sensors had stabilized after the first heating up to 1000°C in N2. After stabilization the sensors underwent further 8 temperature cycles which correspond to over 28h of operation time between 800 - 1000°C. To reduce the loss of combustion heat, chip material around the microthruster structures was partially removed. The effects of thermal insulation were investigated with microthruster chip pairs which were clamped together mechanically. The heater power was varied up to 20W and the temperature distribution in the chip pairs with / without thermal insulation was monitored with 7 integrated thin film sensors.

  10. Comet Ejecta in Aerogel

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Click on image for annotated image

    This image shows a particle impact on the aluminum frame that holds the aerogel tiles. The debris from the impact shot into the adjacent aerogel tile producing the explosion pattern of ejecta framents captured in the material. A nice cratering experiment.

  11. Melamine-formaldehyde aerogels

    DOEpatents

    Pekala, R.W.

    1992-01-14

    Organic aerogels that are transparent and essentially colorless are prepared from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porosity, ultrafine cell/pore sizes, and optical clarity. 3 figs.

  12. Melamine-formaldehyde aerogels

    DOEpatents

    Pekala, Richard Walter

    1992-01-01

    Organic aerogels that are transparent and essentially colorless are prepa from the aqueous, sol-gel polymerization of melamine with formaldehyde. The melamine-formaldehyde (MF) aerogels have low densities, high surface areas, continuous porsity, ultrafine cell/pore sizes, and optical clarity.

  13. Potential use of ceramic coating as a thermal insulation on cooled turbine hardware

    NASA Technical Reports Server (NTRS)

    Liebert, C. H.; Stepka, F. S.

    1976-01-01

    An analysis was made to determine the potential benefits of using a ceramic thermal insulation coating of calcia-stabilized zirconia on cooled engine parts. The analysis was applied to turbine vanes of a high temperature and high pressure core engine and a moderate temperature and low pressure research engine. Measurements made during engine operation showed that the coating substantially reduced vane metal wall temperatures. Evaluation of the durability of the coating on turbine vanes and blades in a furnace and engine were encouraging.

  14. Organic and composite aerogels through ring opening metathesis polymerization (ROMP)

    NASA Astrophysics Data System (ADS)

    Mohite, Dhairyashil P.

    Aerogels are open-cell nanoporous materials, unique in terms of low density, low thermal conductivity, low dielectric constants and high acoustic attenuation. Those exceptional properties stem from their complex hierarchical solid framework (agglomerates of porous, fractal secondary nanoparticles), but they also come at a cost: low mechanical strength. This issue has been resolved by crosslinking silica aerogels with organic polymers. The crosslinking polymer has been assumed to form a conformal coating on the surface of the skeletal framework by covalent bridging elementary building blocks. However, "assuming" is not enough: for correlating nanostructure with bulk material properties, it is important to know the exact location of the polymer on the aerogel backbone. For that investigation, we synthesized a new norbornene derivative of triethoxysilane (Si-NAD) that can be attached to skeletal silica nanoparticles. Those norbornene-modified silica aerogels were crosslinked with polynorbornene by ring opening metathesis polymerization (ROMP). The detailed correlation between nanostructure and mechanical strength was probed with a wide array of characterization methods ranging from molecular to bulk through nano. Subsequently, it was reasoned that since the polymer dominates the exceptional mechanical properties of polymer crosslinked aerogels, purely organic aerogels with the same nanostructure and interparticle connectivity should behave similarly. That was explored and confirmed by: (a) synthesis of a difunctional nadimide monomer (bis-NAD), and preparation of robust polyimide aerogels by ROMP of its norbornene end-caps; and, (b) synthesis of dimensionally stable ROMP-derived polydicyclopentadiene aerogels by grafting the nanostructure with polymethylmethacrylate (PMMA) via free radical chemistry.

  15. Estimation of the thermal conductivity of hemp based insulation material from 3D tomographic images

    NASA Astrophysics Data System (ADS)

    El-Sawalhi, R.; Lux, J.; Salagnac, P.

    2016-08-01

    In this work, we are interested in the structural and thermal characterization of natural fiber insulation materials. The thermal performance of these materials depends on the arrangement of fibers, which is the consequence of the manufacturing process. In order to optimize these materials, thermal conductivity models can be used to correlate some relevant structural parameters with the effective thermal conductivity. However, only a few models are able to take into account the anisotropy of such material related to the fibers orientation, and these models still need realistic input data (fiber orientation distribution, porosity, etc.). The structural characteristics are here directly measured on a 3D tomographic image using advanced image analysis techniques. Critical structural parameters like porosity, pore and fiber size distribution as well as local fiber orientation distribution are measured. The results of the tested conductivity models are then compared with the conductivity tensor obtained by numerical simulation on the discretized 3D microstructure, as well as available experimental measurements. We show that 1D analytical models are generally not suitable for assessing the thermal conductivity of such anisotropic media. Yet, a few anisotropic models can still be of interest to relate some structural parameters, like the fiber orientation distribution, to the thermal properties. Finally, our results emphasize that numerical simulations on 3D realistic microstructure is a very interesting alternative to experimental measurements.

  16. Determination of mechanical and thermal properties of electrical insulation material at 4.2 K

    NASA Astrophysics Data System (ADS)

    Weiss, K.-P.; Westenfelder, S.; Jung, A.; Bagrets, N.; Fietz, W.

    2012-06-01

    For the electrical insulation of superconducting magnets or magnet components, different insulation materials are used that ensure mechanical stability and good electrical insulation properties at low temperatures. Especially glass-fiber-reinforced or sand-filled epoxies are typical material composites that can be used at temperatures down to 4.2 K. For current lead construction within fusion technology, an optimized filled epoxy with respect to mechanical shear strength had to be identified. Therefore different steel/epoxy compositions where examined using the standardized three point bending method. The test specimen were formed putting five layers of glass-fiber lubricated with epoxy between two 1.4429 (316LN) steel frames. The epoxy facing surface of the steel was blasted with glass or corundum. A systematic investigation was performed using different epoxies to get an optimized mechanical performance. The results will be discussed together with data from a sand-filled epoxy compound. For both compounds beside the mechanical properties thermal conductivity and expansion are given in addition.

  17. Method for producing hydrophobic aerogels

    SciTech Connect

    Hrubesh, Lawrence W.; Poco, John F.; Coronado, Paul R.

    1999-01-01

    A method for treating a dried monolithic aerogel containing non-dispersed particles, with an organometallic surface modifying agent to produce hydrophobic aerogels. The dried, porous hydrophobic aerogels contain a protective layer of alkyl groups, such as methyl groups, on the modified surfaces of the pores of the aerogel. The alkyl groups at the aerogel surface typically contain at least one carbon-metal bond per group.

  18. Nearly Seamless Vacuum-Insulated Boxes

    NASA Technical Reports Server (NTRS)

    Stepanian, Christopher J.; Ou, Danny; Hu, Xiangjun

    2010-01-01

    A design concept, and a fabrication process that would implement the design concept, have been proposed for nearly seamless vacuum-insulated boxes that could be the main structural components of a variety of controlled-temperature containers, including common household refrigerators and insulating containers for shipping foods. In a typical case, a vacuum-insulated box would be shaped like a rectangular parallelepiped conventional refrigerator box having five fully closed sides and a hinged door on the sixth side. Although it is possible to construct the five-closed-side portion of the box as an assembly of five unitary vacuum-insulated panels, it is not desirable to do so because the relatively high thermal conductances of the seams between the panels would contribute significant amounts of heat leakage, relative to the leakage through the panels themselves. In contrast, the proposal would make it possible to reduce heat leakage by constructing the five-closed-side portion of the box plus the stationary portion (if any) of the sixth side as a single, seamless unit; the only remaining seam would be the edge seal around the door. The basic cross-sectional configuration of each side of a vacuum-insulated box according to the proposal would be that of a conventional vacuum-insulated panel: a low-density, porous core material filling a partially evacuated space between face sheets. However, neither the face sheets nor the core would be conventional. The face sheets would be opposite sides of a vacuum bag. The core material would be a flexible polymer-modified silica aerogel of the type described in Silica/Polymer and Silica/Polymer/Fiber Composite Aero - gels (MSC-23736) in this issue of NASA Tech Briefs. As noted in that article, the stiffness of this core material against compression is greater than that of prior aerogels. This is an important advantage because it translates to greater retention of thickness and, hence, of insulation performance when pressure is

  19. Evaluating Thermally Damaged Polyimide Insulated Wiring (MIL-W-81381) with Ultrasound

    NASA Technical Reports Server (NTRS)

    Madaras, Eric I.; Anastasi, Robert F.

    2002-01-01

    A series of experiments to investigate the use of ultrasound for measuring wire insulation have been conducted. Initial laboratory tests were performed on MIL-W-81381/7,/12, and /21 aviation wire, a wire that has polyimide (Kapton Registered Trademark) layers for insulation. Samples of this wiring were exposed to 370C temperatures for different periods of time to induce a range of thermal damage. For each exposure, 12 samples of each gauge (12, 16, and 20 gauges) were processed. The velocity of the lowest order axisymmetric ultrasonic guided mode, a mode that is sensitive to the geometry and stiffness of the wire conductor and insulation, was measured. The phase velocity for the 20-gauge MIL-W-81381/7 wire had a baseline value of 3023 +/- 78 m/s. After exposure to the high temperatures, the wire's phase velocity rapidly increased, and reached an asymptotic value of 3598 +/- 20 m/s after 100 hours exposure. Similar behavior was measured for the 16 gauge MIL-W-81381/21 wire and 12 gauge MIL-W-81381/12 wire which had baseline values of 3225 +/- 22 m/s and 3403 +/- 33 m/s respectively, and reached asymptotic values of 3668 +/- 19 m/s, and 3679 +/- 42 m/s respectively. These measured velocity changes represent changes of 19, 14, and 8 percent respectively for the 20, 16, and 12 gauge wires. Finally, some results for a wire with an ethylene tetrafluoroethylene insulation are reported. Qualitatively similar behaviors are noted ultrasonically.

  20. CO2 Insulation for Thermal Control of the Mars Science Laboratory

    NASA Technical Reports Server (NTRS)

    Bhandari, Pradeep; Karlmann, Paul; Anderson, Kevin; Novak, Keith

    2011-01-01

    The National Aeronautics and Space Administration (NASA) is sending a large (>850 kg) rover as part of the Mars Science Laboratory (MSL) mission to Mars in 2011. The rover's primary power source is a Multi-Mission Radioisotope Thermoelectric Generator (MMRTG) that generates roughly 2000 W of heat, which is converted to approximately 110 W of electrical power for use by the rover electronics, science instruments, and mechanism-actuators. The large rover size and extreme thermal environments (cold and hot) for which the rover is designed for led to a sophisticated thermal control system to keep it within allowable temperature limits. The pre-existing Martian atmosphere of low thermal conductivity CO2 gas (8 Torr) is used to thermally protect the rover and its components from the extremely cold Martian environment (temperatures as low as -130 deg C). Conventional vacuum based insulation like Multi Layer Insulation (MLI) is not effective in a gaseous atmosphere, so engineered gaps between the warm rover internal components and the cold rover external structure were employed to implement this thermal isolation. Large gaps would lead to more thermal isolation, but would also require more of the precious volume available within the rover. Therefore, a balance of the degree of thermal isolation achieved vs. the volume of rover utilized is required to reach an acceptable design. The temperature differences between the controlled components and the rover structure vary from location to location so each gap has to be evaluated on a case-by-case basis to arrive at an optimal thickness. For every configuration and temperature difference, there is a critical thickness below which the heat transfer mechanism is dominated by simple gaseous thermal conduction. For larger gaps, the mechanism is dominated by natural convection. In general, convection leads to a poorer level of thermal isolation as compared to conduction. All these considerations play important roles in the