US3009601A - Thermal insulation - Google Patents

Thermal insulation Download PDF

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US3009601A
US3009601A US824690A US82469059A US3009601A US 3009601 A US3009601 A US 3009601A US 824690 A US824690 A US 824690A US 82469059 A US82469059 A US 82469059A US 3009601 A US3009601 A US 3009601A
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insulation
heat
insulating
shields
vacuum
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Ladislas C Matsch
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Union Carbide Corp
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Union Carbide Corp
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Priority to US824690A priority Critical patent/US3009601A/en
Priority to GB18353/60A priority patent/GB925416A/en
Priority to BE592518A priority patent/BE592518A/fr
Priority to FR831809A priority patent/FR1263507A/fr
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F17—STORING OR DISTRIBUTING GASES OR LIQUIDS
    • F17C—VESSELS FOR CONTAINING OR STORING COMPRESSED, LIQUEFIED OR SOLIDIFIED GASES; FIXED-CAPACITY GAS-HOLDERS; FILLING VESSELS WITH, OR DISCHARGING FROM VESSELS, COMPRESSED, LIQUEFIED, OR SOLIDIFIED GASES
    • F17C13/00—Details of vessels or of the filling or discharging of vessels
    • F17C13/001—Thermal insulation specially adapted for cryogenic vessels
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S138/00—Pipes and tubular conduits
    • Y10S138/02—Glass fiber
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T428/00—Stock material or miscellaneous articles
    • Y10T428/24—Structurally defined web or sheet [e.g., overall dimension, etc.]
    • Y10T428/24273—Structurally defined web or sheet [e.g., overall dimension, etc.] including aperture
    • Y10T428/24322—Composite web or sheet
    • Y10T428/24331—Composite web or sheet including nonapertured component

Definitions

  • Sheets-Sheet 3 INSTALLED was DENs
  • the basic sys-tems for insulating the conventional double walled container for the conveyance and storage of low boiling liquefied gases are: for small containers, the Dewar type high vacuum-polished metal surface system, and for large containers, the powder-in-vacuum insulation system, whichuses an insulating powder in the vacuum space between the ⁇ w-alls.
  • This system is described in detail in U.S. Patent 2,395,459.
  • powder-invacuum heat insulation is highly effective in reducing thermal heat loss in many systems, it is not as effective ⁇ as straight vacuumpolished metal surface for containers up to two feet in diameter.
  • Patent 2,396,459 the vacuum being on the order of 0.1 micron of mercury absolute, a thermal conductivity off 9.2 X 104 B.t.u./ (hr.) (ft.) F.) may be achieved.
  • a thermal conductivity off 9.2 X 104 B.t.u./ (hr.) (ft.) F. may be achieved.
  • An insulation thickness of 1.66 inches of a powder-in-vacuum insulation will permit Ian evaporation loss of 7.1% per day.
  • Such lan insulation thickness results in an insulation cross sectional area equal -to the useful cross sectional area of the inner storage vessel. In other words, beyond the thickness of v1.66 inches, the bulk of Ithe insulation which must be stored and/or transported becomes greater than the bulk of Ithe contained stored material.
  • a lower quality reflective surface may be tolerated by interposing several concentric reflective shields within the insulation space as described in U.S. Patent 2,643,022.
  • one of the llimiting diflcullties involved in such an arrangement is in assembling and supporting many reflective shields Within a reasonable insulation thickness so that each shield is properly spaced from adjacent shields at -all points. Proper spacing is an 'absolute necessity, for if two adjacent shields are permitted to contact in even a minute area, the insulating effect of one shield will be essentially eliminated.
  • the number of shields required dependss on their surface reflectivity.
  • the polished surface having a rciiectivity of then at least 10 such shields must be used in'order to achieve a 1% per day storage loss rate in the described vessel.
  • the shields must be spaced as close to ⁇ gether as possible. Allowing for inaccuracies informing and assembling the shields, the spacing of at least 1A inch would appear to be reasonable.
  • Ten shields between the container walls would provide 1l spaces, and taking the thickness of the shields into consideration, would account for an overall thickness of at least 3 inches. Under these circumstances the fabrication of vessels having -a storage loss rate of less than 1% per day would be costly and timeconsuming.
  • Another object of the present invention is to provide a novel insulating material in an insulation system where radiation would otherwise be an important mode of heat transfer.
  • Another object of the invention is to provide in a low heat conductive material wherein radiation is the predominant remaining mode of heat transfer, a multiplicity of parallel radiant heat barriers interposed in said low conductive material for substantially reducing the passage of radi-ant heat therethrough.
  • Yet another object of the invention is to provide in a low heat conductive insulation, a series of spaced, heat reflecting barriers so constructed and arranged as to impede the passage of radiant heat through said insulation without affecting the thermal conductivity thereof.
  • Another object of the present invention is to provide in a restricted gas-evacuated insulating space, a plurality of radiation barriers, said barriers being disposed in spaced relation to each other, and maintained in such spaced position by a low heat conductive spacing material.
  • Still another object of the present invention is to provide in a vacuum-solid insulating space for small portable containers, a multiplicity of radiation barriers comprising spaced and parallel foils of heat refiective material for reducing the transfer of heat by radi-ation, and a spacing material between said radiation barriers, comprising a low-conductive, heat insulating material for reducing the transfer of heat by conduction between said barriers.
  • a further object of the invention is lto provide a mul-tilayer composite insulation system in which gas molecules can move transversely through the layers, so as to facilitate easier evacuation of such system.
  • ⁇ A still further object of the invention is to provide a vacuum, multi-layer composite insulation system which is superior to heretofore proposed vacuum insulating systems in impeding heat transfer without requiring the extremely high vacuums associated with straight vacuum systems.
  • a further object of the present invention is to provide an improved method of fabricating and applying a heat insulation for cylindrical containers wherein the heat insulation comprises a low-conductive, heat insulating material for reducing the transfer of heat by conduction, and incorporates therein a multiplicity of radiant heat barriers for reducing the transfer of heat by radiation.
  • a further object of the present invention is to provide in an enclosed volume defining a gas evacuated insulating space, a novel insulating structure adapted to fill the insulating space and effect contact with the wall surfaces defining the insulating space, said insulating space being characterized by the absence of gross voids, and having a low rate of heat transfer by conduction and radiation.
  • FIG. l is a front elevational view, partly in section, of a double-walled liquid gas container embodying the principles of the invention
  • FIG. 2 is an isometric view of the composite insulating material of the invention shown in a flattened position with parts broken away to expose underlying layers;
  • FIG. 3 is a greatly enlarged detail section view showing the irregular path of heat transfer through the composite insulating material of the invention
  • FIG. 4 is a sectional view taken along line 4 4 of FIG. l, illustrating the spiral wrapping of insulating material of the invention
  • FIG. 5 is a section view similar to FIG. 4, but showing a concentric layered modification thereof;
  • FIG. 6 is a fragmentary elevational view, in section, of a modified double-walled liquid gas container embodying the principles of the invention
  • FIG. 7 is an isometric view similar to FIG. 2, but modified to show a composite insulating material with perforated foil;
  • FIG. 8 is a graph showing the effect of web density on the performance of the present insulating material.
  • FIG. 9 is a graph for selecting an optimum insulating material of the invention for a given system.
  • the insulating qualities of an evacuated insulating space may be substantially enhanced to a degree never before attained with a novel insulating structure, which may occupy part of or the entire insulating space.
  • the insulating structure does not require numerous brace bars or other supports, does not provide gross voids Within the insulating structure, and can also be employed as a novel means for elastically supporting the -insulated inner container.
  • the transmission of heat across a solid-in-vacuum type insulation may be substantially reduced -to a degree greater than has heretofore been possible by the use of a low heat conductive material which incorporates therein a multiplicity of radiation impervious shields to substantially eliminate heat leak by radiation.
  • vacuum as used hereinafter is intended to apply to sub-atmosphereic absolute pressure conditions not substantially greater than 10 microns of mercury, and preferably below 5 microns of mercury.
  • the pressure should preferably be below l micron of mercury.
  • a vacuum insulated space is provided with a low heat conductive material having incorporated therein a multiplicity of radiation barriers disposed substantially transversely to the direction of heat ow in spaced relation to each other.
  • the radiationbarriers or shields of the invention may comprise one or more sheets of heat absorbing material, or preferably thin sheets or layers of a material possessing high reflecting characteristics when exposed to infra-red radiation, such as aluminum or tin foil.
  • the low conductive material also acts as a supporting and spacing material for retaining the radiation barrier sheets in uniformly spaced relation to each other independently of the thickness and stiffness of the barriers. In this manner it is possible for a large number of thin foils to be supportably mounted and maintained in position in an insulation space of limited thickness. A clearance of a few thousandths of an inch between foils is enough to effectively interrupt and reflect the radiant heat. In this way it is possible to provide a large number of shields in a very limited space, ranging up to several hundred shields per inch of composite insulation thickness.
  • FIG. l Shown in FIG. l is a double walled heat insulating container having parallel inner vessel and outer casing walls 10a and 10b and an evacuated insulating space 11 therebetween.
  • a composite insulation material 12 embodying the principles of the invention, and comprising essentially a low heat conductive material 13 having incorporated therein multiple reflective shields or radiation barriers 14 in contiguous relation for diminishing the transfer of heat by radiation across the insulating space l11.
  • the insulation appears as a series of spaced refiectors 14 disposed substantially transversely to direction of heat ow and supportably carried by the low-conductive insulating material.
  • the insulating material uniformly contacts and supports the surface of each radiation shield in superposed relation and, in addition to its primary purpose of serving as an insulating material, constitutes a carrier and spacing material for maintaining a separation space between adjacent shields. No other supports are required to maintain the insulation in operative assembled relation.
  • the radiation shield material 14 to be used in the insulation material 12 of the invention may comprise either a metal or a metal coated material, such as aluminum coated plastic film, or other radiation reiiective material.
  • Radiation refiective materials comprising thin metallic foils are admirably suited in the practice of the present invention.
  • the foils should have suiiicient thickness to resist tearing or other damage during installation. For high-quality'insulations, the foil should be as thin as practical consistent with strength requirements. Thinness is benecial because it facilitates folding and forming the insulation to fit the contour of the insulation space. It also minimizes the weight of the container.
  • low density is additionally important because it reduces the time and the quantity of expensive refrigeration needed to cool down the inner vessel and establish a stable ktemperature gradient through the insulation.
  • Foil thicknesses between 0.2 mm. and 0.002 mm. are suitable, and when aluminum foil is employed, thickness betwen 0.02 mm. and 0.005 mm. are preferred.
  • a preferred reflective shield is 1A mil (0.00025 in. or 0.0062 mm. thick) plain, annealed aluminum foil without lacquer or other coating. Also, any film of oil resulting from the rolling operation should be removed as by washing.
  • Other radiation reflective materials which are susceptible of use in the practice of the invention are tin, silver, gold, copper, cadmium or other metals. The ernissivity of the reflective shield material should -be between about 0.005 and 0.2, and preferably between 0.015 and 0.06.
  • Emissivities of 0.015 to 0.06 (98.5% to 94.2% reiiectivity) are obtainable with aluminum and are preferred in the practice of this invention, while with more expensive materials such as polished silver, copper or gold, emissivities as low as .005 may be obtained.
  • the above ranges represent an optimum balance between the high performance and high cost of low emissivity materials.
  • the reflective shields are perforated so as to permit gas in the insulation space to move radially through the insulation layers, rather than only parallel to the foil layers. This permits the gas molecules to migrate more freely towards the evacuation connection or towards a gas trapping means such as an adsorbent or getter.
  • the base or separating material of the invention is a low heat conductive material such as fiber insulation which is provided in an uncompacted, elastically cornpressible, resilient and fluffy state, preferably in the form of sheets.
  • the present low conductive material is preferably sufficiently compressible ⁇ so that the installed density of such mate-rial as an element of the composite insulation is at least twice that of the uninstalled material.
  • the physical properties of this material known as webs to those skilled in the art, must be closely controlled to obtain the highly composite insulatingr material o-f the present invention. It has been found that compressible sheets of very fine, low conductive fibers which are matted but unbonded together are satisfactory. Resin bonding is frequently employed in the manufacture of fibrous materials but such bonding cannot be tolerated in the insulation of the present invention because of the resulting excessive solid conductive path.
  • Suitable fibers include clean glass filaments having diameters between 0.2 and 5 microns such as those produced by the so-called iiame attenuation process.
  • a fiber diameter range of 0.5 to 3.8 microns is preferred in the practice of this invention. The above ranges represent preferred balances between increasing fragileness and cost of relatively small diameter fibers, and increased conductance and gas pressure sensitivity of relatively large diameter fibers, as will be discussed later in detail.
  • the low conductive separating material of this invention preferably comprises fibers which are substantially randomly disposed within the plane in the installed condition, and the individual 'fibers are also preferably oriented in a direction substantially perpendicular to the flow of heat.
  • the fibers will not be individually confined to a single plane, but rather, in a finite thickness of fibrous material, the fibers will be generally disposed in thin parallel strata with, of course, some indiscriminate cross weaving of bers between adjacent strata.
  • Compressible fibers having diameters in the range of 0.75 to 1.5 microns such as those commercially designated as 108 or AA liber, and fibers designated as 1,12 or B fiber having diameters in the range of 2.5 to 3.8 microns are normally prepared as webs, and are suitable for practicing this invention.
  • the compressible, low conductive material which constitutes a preferred element of the present invention does not include paper type materials which are relatively smooth, non-compressible, and permanently compacted when provided in the sheet form.
  • the present compressible materials are superior to paper materials because in several respects, one being that they minimize the number and size of gross voids in the composite insulation when assembled in the compressed state. This means that the pressure sensitivity of the insulation is minimized; that is, the thermal conductivity does not increase at a rapid rate as the pressure in the vacuum space increases.
  • the reflective shield separating layer must be low conductive in the sense that it presents a high resistance to the flow of heat through the solid material of which it is composed. While we do not wish to be bound by any particular theory, it is believed the principal reasons for the far superior insulating effects achieved by the previously described fiber orientation are the relatively few fibers traversing the thickness of the insulating layer and the very large number of point contacts established between crossing fibers. These point contacts represent the points of bearing between adjacent fibers in the direction of heat flow, and as such, constitute an extremely high resistance to the iiow of heat by conduction. In a given thickness of low conductive material, it is clear that more point contact resistances will be present in fine compressible fibers than in coarse fibers. Alternatively, for a given number of point contact resistances, fine fibers will permit a thinner separating layer than will coarse fibers. This is one important reason why extremely fine compressible fibers are preferred in this invention.
  • Another reason for using extremely fine compressible yfibers is to reduce gaseous conduction through the insulation and to obtain an insulation which is relatively insensitive to moderate changes in residual gas pressure.
  • the path of greatest resistance to heat flow is through the individual particles and across the point contacts between the particles. Gas conduction across the voids may, therefore, be viewed as a short circuit around the principal resistance.
  • the rate of heat transfer by gaseous conduction is dependent upon the number of molecules present and upon the mean-free-path of molecular motion.
  • the path of solid conduction from the first sheet of aluminum foil to the second is greatly lengthened, and encompasses an indefinitely large number of point contact resistances between contacting fibers.
  • a multi-layer insulation having a series of heat reiiecting sheets and a compressible liber oriented web layer of low conductive insulating material therebetween may be particularly efcient in preventing or diminishing heat losses by radiation as well -as by conduction.
  • the radiation shield spacing may be between about per inch using relatively thick webs for separation, and about 50 shields per inch using very thin webs having only a few iibers per unit area of the low conductive layer.
  • a preferred range is between l0 and 30 ⁇ shields per inch.
  • This optimum range is related to the emissivity of the radiation shields, and to the weight per unit area of the web layer used to separate the shields.
  • FIG. 8 illustrates the very pronounced effect of varying the density of the web materials by applying different degrees of compression during installation.
  • Curve A correlates installed web density pf with the portion ksc of the heat transmission due solely to solid conduction through the fibers, and is represented by the following empirical equation:
  • each of the B curves is typical for a given foil emissivity e and a given weight per unit area of the web layer.
  • curve B2 indicates that the contribution of radiation to the total heat transmission is 0.0l4 1103 B.t.u./(hr.) (ft.) F.).
  • the number of layers of foil and web materials which must be installed per inch of composite insulation thickness in the abt/e examples is pf/ or (3.0/4.7) (453.6/12) :24 layers/ mc
  • fy is defined as the weight per unit area of the total web layer used to separate adjacent foils.
  • web material available in sheets weighing 2 gms/sq. ft. will have a value 'y of 2.0 if used singly between foils, and a value of 4.0 if used in a double thickness between foils.
  • Curves C1, C2 and C3 are the sums of heat transmission by solid conduction and by radiation, e.g., C1 is the sum of A and B1. Assuming that heat transmission by gaseous conduction is negligible, the C curves therefore represent total :heat conduction K,L for the insulation. It is entirely proper to assume that gaseous conduction will be negligible for the high quality insulations of this invention wherein heat transfer by all modes isminimized. In order to justify the installation of a large number of radiation shields, it is first necessary to essentially eliminate gaseous conduction by employing :a suitable Vacuum and small fiber diameter web material so that, without shields, radiation becomes Ia major contributor to total heat transmission.
  • the C curves exhibit definite minimums with extensions which approach the radiation curve B on the left and the solid conductance curve A on the right. It is apparent that unless the compression sensitivity of the web materials is recognized and properly used in accordance with the present invention, the composite insu-lating quality may be only a fraction of that which may be obtained by operating in the minimum area of the C curves.
  • the C curves also illustrate the highly detrimental elfectof using the composite insulation to withstand sustained physical loads in service. The occasional practice of requiring the insulation to support the weight of the inner vessel is precluded for the present insulation since the latter would be compressed excessively beneath the vessel and would be too loose above the vessel. The common practice of allowing the insulation to support or brace the walls of the vacuum space against sustained atmospheric pressure force is also to be avoided, that is, the composite multi-layered insulation of the present invention is external load-free.
  • Optimum web density may be obtained by differentiating the sum of Equations l and 2 with respect to density pf, and the following equation is obtained:
  • the selected density pf of 3.0 lb. ⁇ /ft.3 is by no means optimum for the installed composite insulation.
  • a density of 3.0 results in an overall heat transfer coeicient of about 0.17)(10-3 B.t.u./(hr.)(ft.)( F.), whereas the materials are capable of providing a coefficient of 0.05 10"3 B.t.u./ (hr.) (ft.)( F.) ifr installed with an optimum density of 1.2 lb./ft.3.
  • FIG. 9 is a graph of Equations 4 and 5k which permits the designer to select materialsy and to install them properly so that he may obtain a required Ka value in the most economical manner. Assuming any desired overallheat transfer coetiicient Ka, the necessary emissivity-to-web weight relationship can be determined from curve A of FIG. 9. Also, the proper installed density for the yweb material can be determined from curve B. Once the web weight is selected, the number of layers per unit thickness (N) may be calculated using the optimum installed density:
  • N (pf/fy)(453.6/12) (7)
  • a practical limitation is imposed by the physical characteristics of the materials. From FIG. 8, one might infer that ultimately, best performance would be obtained at extremely low densities below those included on the curves, provided that materials can be found of suitably llow emissivity and web weight.
  • the insulation must be compressed suliiciently to prevent sagging and excessive wrinkling, and 'to maintain contact between the webs and the shields. Sagging and wrinkling produces large gross voids within the insulation which take up space in the insulation compartment and contribute little to the insulating effect.
  • Ka ratings for insulations are based on their effectiveness per unit thickness, it will be apparent that sagging or excessive wrinkling will seriously reduce the Ka value.
  • Contact is desirable to produce sufficient friction between the low conductive layers and reflective shields so that the composite insulation may be handled easily and without damage during assembly of equipment such as insulated containers.
  • the installed density of the web material should be not less than 0.5 lb. per cu. ft.
  • Point E represents typical performance of fine perlite powder-in-vacuum
  • point F represents performance of a sub-micron particle size silica aerogel in vacuum
  • Point G is the performance of a clean glass cloth woven of 5-6 micron diameter libers and having a weight of about 2.6 grams per sq. ft. T his cloth was tested in alternate layers with aluminum foil in the same manner as the web-type materials. In woven materials, the fibers are not randomly oriented in the plane of the sheet, but instead bundles of fibers in close longitudinal contact pass alternately from side to side through the sheet. This results in a very'high density material which exhibits very high heat conductance through the fibers. Due to the openness of the weave, cloth materials are also very gas pressure sens1t1ve.
  • an important advantage of the insulation of this invention 1s the very low coefiicients of heat transmission which may be obtained.
  • a thermal conductivity coefficient of O.ll8 10lP3 B.t.n./ (hr.) (ft.) F. has been obtained at a near-optimum web density of 1.6 lbs./ cu. ft.
  • Another advantage of the Web-type alternate layer -insulation is its low weight per unit heat ow resistance. This is an important characteristic for two reasons: first, it achieves minimum tare weight in portable containers, and thus facilitates handling and reduces transportation costs; second, by minimizing the insulation weight one also reduces the amount of expensive refrigeration needed -for cooling the inner vessel to operating temperature and for establishing a stable temperature gradient through the insulation thickness.
  • An insulations weight per unit heat flow resistance is measured by the factor (k) (p), where k is the coefficient of heat transmission (reciprocal of heat resistivity) and p is the total density of the material including shields.
  • the alternate-layer insulation described ⁇ above with a coefficient of 0.118X10-3 B.t.u./(hr.)(ft.)(-F.) was found to have a total ydensity p of 2.5 lbs/cu. ft.
  • its (k) (p) factor is 0.29Xl03, but the present invention contemplates factors as high as 1x10-3.
  • the (k) (p) factor for perlite-in-vacuum is about 9.6 1()-3 and that for sub-micron size silica aerogel in vacuum is about 6.0X 3.
  • An alternate layer insulation using aluminum foil with a woven glass cloth was found to have a (k) (p) factor of 2.75 10-3, still about l0 'fold greater than the illustrative web and foil insulation of this invention.
  • Another 'of the many important advantages in the thermal insulation of the present invention is that the flexibility of the layers of aluminum foil and fiber glass web allows the insulation thickness as a whole to be pliably bent so as to conform to irregularities and changes in the surface conditionsof the container to be insulated.
  • the composite material of the invention is adapted to be applied to contoured surfaces, and is particularly well suited for insulating either flat or cylindrical surfaces.
  • the multiple foil insulation of the invention may be mounted in the insulation space in any one of a variety of ways.
  • the insulation 12 may be mounted concentrically with respect to the inner container 10a, or it may be, as in FIG. 4, spirally wrapped around the inner vessel with one end of the insulation wrapping in contact with the inner vessel 10a,
  • the metal foil may be loosely spirally wrapped around the inner Vessel 10a, the tightness and number of turns being selected preferably to obtain optimum performance as discussed above.
  • the composite insulation material 12 of the invention may be employed in the cylindrical portion 11a of the insulation space 11, and the end portions 11b of the insulation space, including the flat bottom portion and the upper spherical portion, provided with a supplemental low heat conductive material 16.
  • the supplemental low heat conductive materials which may be used in the terminal sections 11b may comprise a finely divided powder of the type disclosed in U.S. Patent No. 2,396,459, or a thermal insulation such as disclosed in the co-pending application to L. C. Matsch et al., Serial No. 580,897, filed April 26, 1956, now Patent No. 2,967,152, or any other suitably low conductive material.
  • the supplemental insulation 16 provides the means for producing low thermal heat transfers in containers of a wide variety of shapes.
  • the cooperative relationship between the supplemental insulation 16 and the composite insulation 12 meets the requirements of the most critical present day insulation standards, and has extended the usefulness and capabilities of the present invention.
  • a very significant advantage of the present invention arises from the elastic properties of the insulation, particularly when a fibrous insulation is employed in the annular insulating space of a double walled container.
  • the ability of the insulation to give and resist movement of the inner container, and to restore or expand itself when the forces exerted upon it are relaxed, enables -it to operate along the lines of a shock mount.
  • Obvious advantages to using the insulation as an elastic support are that the inner vessel is maintained in substantially centered position, and the need for lateral braces or other centering devices is obviated, thus further reducing the heat vleak into the container. It is to be understood, however, that the present invention does not provide vertical support for the inner vessel, and that specific means for vertical support must be provided.
  • the aluminum foil 114 is provided with passages or perforations 115 preferably arranged in helical or spiral rows, the perforations in any one layer of foil being out of registry with the perforations in the adjacent foil layers.
  • This arrangement affords means for providing a suitable number of perforations in the foil 114 without noticeably reducing the shielding properties thereof. Suitable perforations are 1/16 in. diameter holes pricked or punched on 11/2 in. centers.
  • the function of the perforations is to permit gas in the insulation space to move radially through the insulation layers, rather than only parallel to the foil layers. This permits the gas molecules to migrate more freely towards the evacuation connection or toward a gas trap ping means such as an adsorbent or getter. Also, the perforations permit the migration of cO-ndensable gases to the cold outer wall 110a of the inner vessel, where they form deposits having negligible vapor pressure. Perforations are especially beneficial in systems where the insulation does not fill the entire space but is omitted from one or more free flow channels running :from the evacuation connection to remote points within the insulation space. For example in FIG.
  • space 116 between the outer-most foil layer 113:1 and the outer wall 110i; of the vacuum space comprises an open channel leading to an evacuation connection (not shown). Gas molecules trapped near cold wall ln are free to migrate through the holes 115 in foils 1114 and through webs 113 until they reach low flow resistance channel 116.
  • the present invention provides in a solid-in-vacuum type insulation, a compressible low heat conductive material having incorporated therein multiple radiation shields for impeding radiative heat transmission through the insulation, while minimizing the lflow of heat by conduction therethrough.
  • the low conductive material uniformly supports and maintains the radiation shields in spaced relation.
  • a low conductive material which is admirably suited for use in the practice of the invention is one having a fibrous structure oriented in a direction perpendicular to the direction of heat flow. Possessed of a relatively small percentage of solid material per unit volume, the low conductive insulating material provides a very small, solid conduction heat path between radiation foils, and is remarkably efiicient in minimizing the transmission of heat leak by conduction.
  • insulating systems of the invention using a fine diameter, -low conductive, compressible fiber-type insulating material, have been found to be superior to any lmown insulating system.
  • the present insulation achieves low thermal conductivities, which are comparable or superior to those obtained with either high quality straight vacuums or the best poWder-in-vacuum systems known, yet is considerably less expensive than either of these forms of insulation, and does not require as low absolute pressures as straight vacuum-polished metal insulating systems.
  • independent support means such as high strength plastic spacers, may be provided in the insulation space to support the walls defining such space from the load of atmospheric pressure.
  • a composite multielayered, external load-free insulation in said space comprising low conductive fibrous sheet material Vlayers composed of fibers for reducing heat transfer by gaseous conduction and thin, iieXible radiant heat refiecting shields, said radiant heat reiiecting shields being supportably carried in superposed relation by said fibrous sheet layers to provide a large number of radiant heat reliecting shields in a limited space for reducing the transmission of radiant heat across said space without perceptively increasing the heat transmission by solid conduction thereacross, each radiant heat reflecting shield being disposed in contiguous relation on opposite sides with a layer of the fibrous sheet material, the fibers of said fibrous sheet material being oriented substantially perpendicular to the direction of heat inleak across the insulating space, said fibrous sheet material being an elastically compressible web composed of fibers having diameters between about 0.2 and 5 microns, said radiant heat refiecting shields having a thickness less than a
  • a composite multi-layered, external load-free insulation in said space comprising low conductive fibrous sheet material layers composed of fibers for reducing heat transfer by gaseous conduction and thin, fieXible radiant heat retlecting shields, said radiant heat reiiecting shields being supportably carried in superposed relation by said fibrous sheet layers to provide a large number of radiant heat reflecting shields in a limited space for reducing the transmission of radiant heat across said space without perceptively increasing the heat transmission by solid conduction thereacross, each radiant heat reflecting shield being disposed in contiguous relation on opposite sides with a layer of the fibrous sheet material, the fibers of said fibrous sheet material being oriented substantially perpendicular to the direction of heat inleak across the insulating space, said fibrous sheet material being an elastically compressible web composed of fibers having diameters between about 0.2 and 5 microns, said radiant heat reflecting shields having a thickness less than about 0.2 mm. and being perforated to provide flow paths

Landscapes

  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Thermal Insulation (AREA)
  • Filling Or Discharging Of Gas Storage Vessels (AREA)
US824690A 1959-07-02 1959-07-02 Thermal insulation Expired - Lifetime US3009601A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
US824690A US3009601A (en) 1959-07-02 1959-07-02 Thermal insulation
GB18353/60A GB925416A (en) 1959-07-02 1960-05-24 Thermal insulation
BE592518A BE592518A (fr) 1959-07-02 1960-07-01 Procédé de production d'une structure calorifuge
FR831809A FR1263507A (fr) 1959-07-02 1960-07-01 Procédé de production d'une structure calorifuge

Applications Claiming Priority (1)

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US824690A US3009601A (en) 1959-07-02 1959-07-02 Thermal insulation

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Cited By (46)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124853A (en) * 1964-03-17 Process for forming insulation and resulting product
US3145515A (en) * 1962-04-24 1964-08-25 Union Carbide Corp Manufacture of multi-layer insulated structure
US3212529A (en) * 1961-12-11 1965-10-19 Owens Corning Fiberglass Corp Collapsible duct section
US3236406A (en) * 1963-08-29 1966-02-22 Union Carbide Corp Spaced wall insulated container
US3240234A (en) * 1960-02-24 1966-03-15 Union Carbide Corp Hose for low-temperature liquids
US3346016A (en) * 1964-01-02 1967-10-10 Johns Manville High temperature thermal insulation
US3354021A (en) * 1963-09-18 1967-11-21 Comp Generale Electricite Thermal insulating devices
US3357587A (en) * 1962-01-04 1967-12-12 Linde Ag Thermal insulation suitable for vacuum bottles and the like
US3379330A (en) * 1965-12-08 1968-04-23 Nasa Usa Cryogenic insulation system
US3385743A (en) * 1965-04-05 1968-05-28 Richard W. Backberg Self-adhering surface finish laminate
US3415288A (en) * 1966-12-27 1968-12-10 Califoam Corp Of America Heat insulated conduit and method of making same
US3416693A (en) * 1966-12-07 1968-12-17 Cryogenic Eng Co Refrigeration shielded dewar vessel
US3510363A (en) * 1966-11-02 1970-05-05 Rca Corp Thermoelectric generator suitable for use at elevated temperatures in a vacuum
US3514006A (en) * 1966-05-19 1970-05-26 British Oxygen Co Ltd Vacuum insulated vessels
US3525452A (en) * 1967-03-31 1970-08-25 Linde Ag Method and device for thermally insulating a vessel
JPS4887618U (fr) * 1972-01-25 1973-10-23
US3814275A (en) * 1972-04-03 1974-06-04 Mc Donnell Douglas Corp Cryogenic storage vessel
US3929167A (en) * 1974-10-29 1975-12-30 Bruce T Bickel Insulation device for protection against heat
US3952777A (en) * 1972-12-20 1976-04-27 Brown Boveri-Sulzer Turbomaschinen Aktiengesellschaft Hollow body for heated gases
JPS5140488Y1 (fr) * 1971-02-26 1976-10-02
US4050607A (en) * 1972-04-07 1977-09-27 The Dow Chemical Company Insulation of vessels having curved surfaces
US4055465A (en) * 1975-07-24 1977-10-25 Commissiariat A L'energie Atomique Device for thermal insulation of a vessel wall
US4105819A (en) * 1975-03-04 1978-08-08 Technigaz Laminated sheets particularly for cryogenic enclosures, pipes, and the like
US4140073A (en) * 1977-07-12 1979-02-20 Frigitemp Corporation Thermal barrier system for liquefied gas tank
US4168013A (en) * 1977-10-17 1979-09-18 Trans Temp Inc. High temperature insulating container
US4287720A (en) * 1979-11-21 1981-09-08 Union Carbide Corporation Cryogenic liquid container
US4323620A (en) * 1978-06-30 1982-04-06 Yuasa Battery Company Limited Multilayer heat insulator
US4395455A (en) * 1982-01-28 1983-07-26 E. I. Du Pont De Nemours And Company Polyester fiberfill batting having improved thermal insulating properties
US4433019A (en) * 1982-11-08 1984-02-21 Chumbley James F Insulative fabric
US4692363A (en) * 1982-09-27 1987-09-08 Brown, Boveri & Cie Ag Thermal insulation
US4777086A (en) * 1987-10-26 1988-10-11 Owens-Corning Fiberglas Corporation Low density insulation product
US4862674A (en) * 1985-12-17 1989-09-05 Lejondahl Lars Erik Thermally insulated container
US4919366A (en) * 1988-09-23 1990-04-24 Mmi Incorporated Heat resistive wall assembly for a space vehicle
US4954685A (en) * 1987-07-31 1990-09-04 Tokyo Electron Limited Heating furnace for semiconductor wafers
US5337917A (en) * 1991-10-21 1994-08-16 Sandia Corporation Crash resistant container
US5492242A (en) * 1992-07-11 1996-02-20 Gall; Karsten Container for fluids or fluid-like products
US5797513A (en) * 1996-02-29 1998-08-25 Owens Corning Fiberglas Technology, Inc. Insulated vessels
US20080104969A1 (en) * 2006-11-08 2008-05-08 Gm Global Technology Operations, Inc. Acoustic fluid level monitoring
WO2008115143A1 (fr) * 2007-03-21 2008-09-25 Fidens Holding Ab Plaque isolante destinée à une utilisation dans une isolation thermique, isolation et procédé de fabrication de celle-ci
WO2009023891A1 (fr) * 2007-08-22 2009-02-26 Werner Hermeling Dispositif de stockage et de transport de gaz liquéfiés par voie cryogénique
US20100146992A1 (en) * 2008-12-10 2010-06-17 Miller Thomas M Insulation for storage or transport of cryogenic fluids
US20120279971A1 (en) * 2008-09-23 2012-11-08 Aerovironment Inc. Cryogenic Liquid Tank
US20130133776A1 (en) * 2011-03-18 2013-05-30 Immo Gärtner Process for manufacturing a heat-insulated uncoupling element and an uncoupling element, especially for exhaust gas lines of internal combustion engines
US9316430B2 (en) 2013-01-14 2016-04-19 Fairlane Industries Inc. Thermal insulating material
AT524147A1 (de) * 2020-09-14 2022-03-15 Rep Ip Ag Transportbehälter
WO2025212252A1 (fr) * 2024-04-03 2025-10-09 Aerospace Fabrication & Materials, Llc Système d'isolation multicouche avec couche d'espacement alvéolée

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH592520A5 (fr) * 1974-12-07 1977-10-31 Goldschmidt Ag Th

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US903878A (en) * 1905-05-11 1908-11-17 Hugo Mock Heat-insulator.
GB143219A (en) * 1916-11-08 1920-12-09 Petits Fils Francois Wendel Improvements in transport and storage vessels for liquid air or liquid gas
US1626655A (en) * 1923-08-30 1927-05-03 Westinghouse Electric & Mfg Co Heat-insulating wall
US2104548A (en) * 1931-07-03 1938-01-04 Gen Motors Corp Refrigerating apparatus
US2150182A (en) * 1935-03-13 1939-03-14 Termisk Isolation Ab Insulation
US2345204A (en) * 1942-04-02 1944-03-28 Mobile Refrigeration Inc Interior chamber insulation
GB683855A (en) * 1949-12-30 1952-12-03 British Thomson Houston Co Ltd Improvements in and relating to insulating structures
US2676773A (en) * 1951-01-08 1954-04-27 North American Aviation Inc Aircraft insulated fuel tank
GB715174A (en) * 1951-07-14 1954-09-08 Gen Electric Improvements in and relating to thermal insulation
US2776776A (en) * 1952-07-11 1957-01-08 Gen Electric Liquefied gas container

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US903878A (en) * 1905-05-11 1908-11-17 Hugo Mock Heat-insulator.
GB143219A (en) * 1916-11-08 1920-12-09 Petits Fils Francois Wendel Improvements in transport and storage vessels for liquid air or liquid gas
US1626655A (en) * 1923-08-30 1927-05-03 Westinghouse Electric & Mfg Co Heat-insulating wall
US2104548A (en) * 1931-07-03 1938-01-04 Gen Motors Corp Refrigerating apparatus
US2150182A (en) * 1935-03-13 1939-03-14 Termisk Isolation Ab Insulation
US2345204A (en) * 1942-04-02 1944-03-28 Mobile Refrigeration Inc Interior chamber insulation
GB683855A (en) * 1949-12-30 1952-12-03 British Thomson Houston Co Ltd Improvements in and relating to insulating structures
US2676773A (en) * 1951-01-08 1954-04-27 North American Aviation Inc Aircraft insulated fuel tank
GB715174A (en) * 1951-07-14 1954-09-08 Gen Electric Improvements in and relating to thermal insulation
US2776776A (en) * 1952-07-11 1957-01-08 Gen Electric Liquefied gas container

Cited By (55)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3124853A (en) * 1964-03-17 Process for forming insulation and resulting product
US3240234A (en) * 1960-02-24 1966-03-15 Union Carbide Corp Hose for low-temperature liquids
US3212529A (en) * 1961-12-11 1965-10-19 Owens Corning Fiberglass Corp Collapsible duct section
US3357587A (en) * 1962-01-04 1967-12-12 Linde Ag Thermal insulation suitable for vacuum bottles and the like
US3145515A (en) * 1962-04-24 1964-08-25 Union Carbide Corp Manufacture of multi-layer insulated structure
US3236406A (en) * 1963-08-29 1966-02-22 Union Carbide Corp Spaced wall insulated container
US3354021A (en) * 1963-09-18 1967-11-21 Comp Generale Electricite Thermal insulating devices
US3346016A (en) * 1964-01-02 1967-10-10 Johns Manville High temperature thermal insulation
US3385743A (en) * 1965-04-05 1968-05-28 Richard W. Backberg Self-adhering surface finish laminate
US3379330A (en) * 1965-12-08 1968-04-23 Nasa Usa Cryogenic insulation system
US3514006A (en) * 1966-05-19 1970-05-26 British Oxygen Co Ltd Vacuum insulated vessels
US3510363A (en) * 1966-11-02 1970-05-05 Rca Corp Thermoelectric generator suitable for use at elevated temperatures in a vacuum
US3416693A (en) * 1966-12-07 1968-12-17 Cryogenic Eng Co Refrigeration shielded dewar vessel
US3415288A (en) * 1966-12-27 1968-12-10 Califoam Corp Of America Heat insulated conduit and method of making same
US3525452A (en) * 1967-03-31 1970-08-25 Linde Ag Method and device for thermally insulating a vessel
JPS5140488Y1 (fr) * 1971-02-26 1976-10-02
JPS4887618U (fr) * 1972-01-25 1973-10-23
US3814275A (en) * 1972-04-03 1974-06-04 Mc Donnell Douglas Corp Cryogenic storage vessel
US4050607A (en) * 1972-04-07 1977-09-27 The Dow Chemical Company Insulation of vessels having curved surfaces
US3952777A (en) * 1972-12-20 1976-04-27 Brown Boveri-Sulzer Turbomaschinen Aktiengesellschaft Hollow body for heated gases
US3929167A (en) * 1974-10-29 1975-12-30 Bruce T Bickel Insulation device for protection against heat
US4105819A (en) * 1975-03-04 1978-08-08 Technigaz Laminated sheets particularly for cryogenic enclosures, pipes, and the like
US4055465A (en) * 1975-07-24 1977-10-25 Commissiariat A L'energie Atomique Device for thermal insulation of a vessel wall
US4140073A (en) * 1977-07-12 1979-02-20 Frigitemp Corporation Thermal barrier system for liquefied gas tank
US4168013A (en) * 1977-10-17 1979-09-18 Trans Temp Inc. High temperature insulating container
US4323620A (en) * 1978-06-30 1982-04-06 Yuasa Battery Company Limited Multilayer heat insulator
US4287720A (en) * 1979-11-21 1981-09-08 Union Carbide Corporation Cryogenic liquid container
US4395455A (en) * 1982-01-28 1983-07-26 E. I. Du Pont De Nemours And Company Polyester fiberfill batting having improved thermal insulating properties
US4692363A (en) * 1982-09-27 1987-09-08 Brown, Boveri & Cie Ag Thermal insulation
US4433019A (en) * 1982-11-08 1984-02-21 Chumbley James F Insulative fabric
US4862674A (en) * 1985-12-17 1989-09-05 Lejondahl Lars Erik Thermally insulated container
US4954685A (en) * 1987-07-31 1990-09-04 Tokyo Electron Limited Heating furnace for semiconductor wafers
US4777086A (en) * 1987-10-26 1988-10-11 Owens-Corning Fiberglas Corporation Low density insulation product
US4919366A (en) * 1988-09-23 1990-04-24 Mmi Incorporated Heat resistive wall assembly for a space vehicle
US5337917A (en) * 1991-10-21 1994-08-16 Sandia Corporation Crash resistant container
US5492242A (en) * 1992-07-11 1996-02-20 Gall; Karsten Container for fluids or fluid-like products
US5797513A (en) * 1996-02-29 1998-08-25 Owens Corning Fiberglas Technology, Inc. Insulated vessels
US5971198A (en) * 1996-02-29 1999-10-26 Owens Corning Fiberglas Technology, Inc. Insulated vessels
US20080104969A1 (en) * 2006-11-08 2008-05-08 Gm Global Technology Operations, Inc. Acoustic fluid level monitoring
US7739909B2 (en) * 2006-11-08 2010-06-22 Gm Global Technology Operations, Inc. Acoustic fluid level monitoring
US20100104802A1 (en) * 2007-03-21 2010-04-29 Fidens Holding Ab Insulation layer for use in thermal insulation, insulation and method of manufacturing such
WO2008115143A1 (fr) * 2007-03-21 2008-09-25 Fidens Holding Ab Plaque isolante destinée à une utilisation dans une isolation thermique, isolation et procédé de fabrication de celle-ci
WO2009023891A1 (fr) * 2007-08-22 2009-02-26 Werner Hermeling Dispositif de stockage et de transport de gaz liquéfiés par voie cryogénique
US9829155B2 (en) * 2008-09-23 2017-11-28 Aerovironment, Inc. Cryogenic liquid tank
US11346501B2 (en) 2008-09-23 2022-05-31 Aerovironment, Inc. Cryogenic liquid tank
US20120279971A1 (en) * 2008-09-23 2012-11-08 Aerovironment Inc. Cryogenic Liquid Tank
US10584828B2 (en) 2008-09-23 2020-03-10 Aerovironment, Inc. Cryogenic liquid tank
WO2010068254A3 (fr) * 2008-12-10 2010-08-26 Cabot Corporation Isolation pour stockage ou transport de fluides cryogéniques
US20100146992A1 (en) * 2008-12-10 2010-06-17 Miller Thomas M Insulation for storage or transport of cryogenic fluids
US9046199B2 (en) * 2011-03-18 2015-06-02 BOA Balg- und Kompensatoren- Technologie GmbH Process for manufacturing a heat-insulated uncoupling element and an uncoupling element, especially for exhaust gas lines of internal combustion engines
US20130133776A1 (en) * 2011-03-18 2013-05-30 Immo Gärtner Process for manufacturing a heat-insulated uncoupling element and an uncoupling element, especially for exhaust gas lines of internal combustion engines
US9316430B2 (en) 2013-01-14 2016-04-19 Fairlane Industries Inc. Thermal insulating material
AT524147A1 (de) * 2020-09-14 2022-03-15 Rep Ip Ag Transportbehälter
US12583662B2 (en) 2020-09-14 2026-03-24 Rep Ip Ag Transport container
WO2025212252A1 (fr) * 2024-04-03 2025-10-09 Aerospace Fabrication & Materials, Llc Système d'isolation multicouche avec couche d'espacement alvéolée

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Publication number Publication date
BE592518A (fr) 1960-10-31
GB925416A (en) 1963-05-08

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