EFFECTIVE HEAT SHIELDING AND HEAT DISPERSING APPARATUS

Abstract

A heat shielding apparatus capable of dynamically responding to incident heat flux of changing ratio of thermal radiation and convective heat, wherein the dynamic response comprises thermal conduction of the incident heat to a region of lower ambient temperature, and substantive reflection of the incident thermal radiation.

Claims

1. A heat shielding apparatus, comprising: a substantially planar layer of material; wherein the material comprises a carbon-based component; and the carbon-based component exhibits at least one thermally anisotropic property.

2. The heat shielding apparatus of claim 1, wherein: the apparatus comprises a heat conducting panel; the panel is characterized by a length L, a width W, and a thickness T; and L>T, and W>T.

3. The heat shielding apparatus of claim 1, wherein the thermally anisotropic property comprises anisotropic thermal conductivity.

4. The heat shielding apparatus of claim 1, wherein the material exhibits greater thermal conductivity in a first direction within the substantially planar layer of material than in a second direction normal to the planar layer of material.

5. The heat shielding apparatus of claim 1 wherein the carbon-based material comprises Carbon Fiber Tow.

6. The heat shielding apparatus of claim 1, further comprising a plurality of layers of carbon-based material in which each layer is in direct contact with an adjacent layer.

7. The heat shielding apparatus of claim 1, further comprising a plurality of layers of carbon-based material in which at least one layer is separated from an adjacent layer by an insulating layer, wherein the insulating comprises a material having a lower thermal conductivity, than the adjacent carbon-based layer in a direction corresponding to the length L.

8. The heat shielding apparatus of claim 1, further comprising a reflective metallic layer.

9. The heat shielding apparatus of claim 1 comprising a thermally insulating layer.

10. The heat shielding apparatus of claim 5, wherein: the Carbon Fiber Tow comprises a bundle of fibers; and the bundle of fibers are bound together by an adhesive comprising a sodium silicate glue.

11. The heat shielding apparatus of claim 5, wherein: the Carbon Fiber Tow comprises a bundle of fibers; and the bundle of fibers are bound together by a high-temperature thread.

12. The heat shielding apparatus of claim 5, wherein: the Carbon Fiber Tow comprises a bundle of fibers; and the bundle of fibers are bound together by a high temperature thread made from carbon nanotubes.

13. The heat shielding apparatus of claim 5, wherein: an externally visible arrow or other indicia is made available to indicate the major direction of the at least one thermally anisotropic property.

14. A protective garment comprising the heat shielding apparatus of claim 1.

15. A protective thermal blanket comprising the heat shielding apparatus of claim 1.

14. A protective thermal shelter comprising the heat shielding apparatus of claim 1.

15. A heat shielding apparatus capable of dynamically responding to incident heat flux of changing ratio of thermal radiation and convective heat, wherein the dynamic response comprises thermal conduction of the incident heat to a region of lower ambient temperature, and substantive reflection of the incident thermal radiation.

Description

BRIEF DESCRIPTIONS OF THE DRAWINGS

[0031] FIG. 1 illustrates one embodiment of the construction of a heat panel.

[0032] FIG. 2 illustrates the preferred embodiment of the construction of a heat panel.

DETAILED DESCRIPTION OF PREFERRED EXEMPLARY EMBODIMENTS

[0033] The following detailed description is merely exemplary in nature and is not intended to limit the invention or the application and uses of the invention. Furthermore, there is no intention to be bound by any theory presented in the preceding background or the following detailed description.

[0034] A 0.020 inch diameter wire square copper mesh (FIG. 2B) with 220×220 wires per inch is cut into a 6-inch by 8-inch panel. Ten, 8-inch long bundles of 50 k carbon fiber tow are stacked lengthwise on the copper mesh such that the strands are parallel and spread out to a width of 1 inch. Another stack of ten, 8-inch long bundles is similarly positioned adjacent and in contact with the first bundle, is also spread out to cover a width of 1 inch. Repeating this construction for the remaining 4 inches of width such that each stack of bundles has been laid parallel and adjacent one another, the entire area of 6 inches by 8 inches is covered by ten layers of carbon fiber tow oriented with the highest thermal conductivity in the length direction (FIG. 2C). The tow is then covered by a layer of 0.0047″ diameter wire square copper mesh with 70×70 wires per inch (FIG. 2D). In alternative embodiments, the carbon fiber tow be positioned such that one or more layers are parallel and in the lengthwise direction, and other layers are parallel but in a different direction such as the width direction.

[0035] A layer of 6″×8″ fire retardant carbon fiber sheet (FIG. 2A) is placed underneath the 220×220 copper mesh layer, and both the entire stack including the upper copper mesh layer, the carbon fiber tow layer, the lower copper mesh layer and the insulation layer are then sewn together an using ultra-high temperature (e.g. ceramic or Inconel core) thread (FIG. 2E). The stitching pattern comprises stitches parallel to the length of the panel, spaced apart by about 1 inch, but could be spaced closer together or farther apart. A second row of stitches, perpendicular to the length of the panel, is made across the entire width of the panel, also sewing all layers together, and also about an inch apart. The stitching in a square-cross pattern allows easier bending of the panel along its length and width directions. And the close spacing of the stitches allows the panel to be cut into arbitrary shapes while still keeping the carbon tow securely in place. An externally visible arrow or other indicia is made available to indicate the direction of greatest thermal conductivity.

[0036] In an additional preferred embodiment, the insulation layer is the bottom layer for the construction of a panel. Multiple strips of 50 k carbon fiber tow with a thickness determined by the number of layers used, are created. A final, uppermost layer of 50 k carbon fiber tow is immersed in sodium silicate glue, and dried in an oven. All layers of the carbon fiber tow are affixed to a wire mesh using 1 k carbon tow as thread. The carbon tow, the copper mesh and the insulation layer are sewn together using ultra-high temperature thread. Together, the layers comprise a heat shield in the form of a panel. The panel can then be used by simple placement between a heat source and a heat sensitive area, or can be attached by any combination of glue, Velcro, tape, hooks, screws, nails, or the like.

Example 1

[0037] A swath of PBI fabric, (PBI Performance Products, Charlotte, N.C.), often used as turnout gear for firefighters, was subjected to a heat stress test. A butane torch was placed 5.25 inches from the front surface of the fabric, which in prior tests resulted in a front side temperature of 800 degrees C. in under two minutes. An IR sensor was pointed at the rear face of the PBI fabric such that the measured spot was directly behind the target spot of the flame on the front side of the fabric. A timer was started simultaneously to the onset of flame, and temperature indicated by the thermocouple was recorded at regular intervals of 15 seconds for a duration of two minutes. The recorded temperature rose rapidly to a value of about 538 deg. C., before a hole was formed at the front spot where the flame was pointed. The hole formed in under 40 seconds and the test was stopped. The PBI fabric was observed to have blackened around the edges of the missing (burned) material.

[0038] A heat panel made similarly to the description held forth in the “Detailed Description of Preferred Exemplary Embodiments” was sewn onto a swath of PBI fabric and subjected to the same heat stress test as was conducted on the PBI fabric by itself, where the butane torch was aimed at the front face of the heat panel. For this test, a thermocouple was employed on the rear face of the PBI fabric to measure temperature. The tip of the thermocouple was positioned in physical contact with the PBI fabric at a spot just behind where the incident heat from the butane torch was applied. The temperature was again measured at regular, 15 second intervals and recorded. From a starting temperature of 25 deg. C., temperature of the rear face of the PBI rose in approximately linear fashion to a final temperature of 140 deg. C. after two minutes of continuous exposure to the flame. The PBI fabric remained intact, although a light, faint brown tint could be seen on the rear face.

[0039] From these experimental data, it was concluded that the effect of the heat panel was to lower the temperature of the PBI fabric by over 600 deg. C. after two minutes of constant exposure to the heat source.