THERMAL INSULATOR HAVING INFRARED-REFLECTIVE COATING
A thermal insulator includes a plurality of insulation layers with a first insulation layer spaced apart from a second insulation layer such that there is an open gap there between. At least one of the first insulation layer or the second insulation layer includes a substrate and an infrared-reflective coating on the substrate.
1 . An insulator comprising:
a refractory member including a non-metallic, infrared-reflective surface;
a radiant surface adjacent the refractory member; and
a vacuum between the radiant surface and the refractory member.
2 . A thermal insulator comprising:
a plurality of insulation layers including a first insulation layer spaced apart from a second insulation layer such that there is an open gap there between, at least one of the first insulation layer or the second insulation layer including a substrate and an infrared-reflective coating on the substrate.
3 . The thermal insulator as recited in claim 2 , wherein the substrate is metallic.
4 . The thermal insulator as recited in claim 3 , wherein the substrate is selected from a group consisting of tungsten, molybdenum, superalloy material and combinations thereof.
5 . The thermal insulator as recited in claim 2 , wherein the infrared-reflective coating includes at least one of a boride, a nitride or a carbide of a refractory metal.
6 . The thermal insulator as recited in claim 5 , wherein the refractory metal includes molybdenum.
7 . The thermal insulator as recited in claim 5 , wherein the refractory metal includes tungsten.
8 . The thermal insulator as recited in claim 2 , wherein the plurality of insulation layers include at least one insulation layer that is free of any infrared-reflective coating and that is spaced apart from a neighboring insulation layer that has an infrared-reflective coating.
9 . The thermal insulator as recited in claim 8 , wherein the at least one insulation layer that is free of the infrared-reflective coating is selected from a group consisting of tungsten, molybdenum, a superalloy material and combinations thereof.
10 . The thermal insulator as recited in claim 2 , including a spacer between the first insulation layer and the second insulation layer establishing the open gap there between.
11 . The thermal insulator as recited in claim 2 , wherein the plurality of insulation layers includes an alternating arrangement of insulation layers having the substrate and the infrared-reflective coating and insulation layers that are free of any infrared-reflective coating.
12 . The thermal insulator as recited in claim 2 , wherein the plurality of insulation layers define a window.
13 . The thermal insulator as recited in claim 2 , wherein the plurality of insulation layers include from 50 to 100 insulation layers.
14 . The thermal insulator as recited in claim 2 , wherein the plurality of insulation layers includes a number N 1 of insulation layers that are free of any infrared-reflective coating and a number N 2 of insulation layers that have an infrared-reflective coating, and a ratio N 1 :N 2 is from 1:1 to 4:1.
15 . The thermal insulator as recited in claim 2 , wherein the plurality of insulation layers includes a number N 1 of insulation layers that are free of any infrared-reflective coating and a number N 2 of insulation layers that have an infrared-reflective coating, and a ratio N 1 :N 2 is from 20:1 to 50:1.
16 . A solar receiver comprising:
a conduit for receiving a working fluid to be heated by solar energy; and
a thermal insulator arranged around the periphery of the conduit, the thermal insulator comprising a plurality of insulation layers including a first insulation layer spaced apart from a second insulation layer such that there is an open gap there between, at least one of the first insulation layer or the second insulation layer including a substrate and an infrared-reflective coating on the substrate.
17 . The solar receiver as recited in claim 16 , wherein the thermal insulator defines a window permitting the solar energy to impinge upon the conduit.
18 . The solar receiver as recited in claim 16 , wherein the substrate is selected from a group consisting of tungsten, molybdenum, a superalloy material and combinations thereof.
19 . The solar receiver as recited in claim 16 , wherein the infrared-reflective coating includes at least one of a boride, a nitride or a carbide of a refractory metal.
20 . A solar thermal propulsion device comprising:
a conduit having an inlet for receiving a working fluid and an outlet for discharging the working fluid;
a window adjacent the conduit for permitting solar energy to impinge upon the conduit to heat the working fluid;
a nozzle in receiving communication with the outlet; and
a thermal insulator arranged around the periphery of the conduit, the thermal insulator comprising a plurality of insulation layers including a first insulation layer spaced apart from a second insulation layer such that there is an open gap there between, at least one of the first insulation layer or the second insulation layer including a substrate and an infrared-reflective coating on the substrate.
21 . The solar thermal propulsion device as recited in claim 20 , wherein the substrate is selected from a group consisting of tungsten, molybdenum, a superalloy material and combinations thereof.
22 . The solar thermal propulsion device as recited in claim 20 , wherein the infrared-reflective coating includes at least one of a boride, a nitride or a carbide of a refractory metal.