High temperature solar absorber coating and method of applying same

• US 4,211,210 A
• Filed: 03/01/1978
• Issued: 07/08/1980
• Est. Priority Date: 02/02/1977
• Status: Expired due to Term

• Current Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Original Assignee: Exxon Research and Engineering Company (Exxon Mobil Corporation)
• Inventors: Young, Archie R. II, Muenker, Adolf H.
• Primary Examiner(s): Yeung, James C.
• Application Number:
  US05/882,438
• Time in Patent Office: 860 Days
• Field of Search: 126/270, 126/271, 126/901, 428/469, 428/539, 428/632, 428/633, 350/1.1, 350/1.7, 350/166, 350/290
• US Class Current: 126/684
• CPC Class Codes: C04B 35/26 based on ferrites
• CPC Class Codes: C09D 5/32 Radiation-absorbing paints protection against X-, gamma- or corpuscular radiation G21F
• CPC Class Codes: F24S 20/20 Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants
• CPC Class Codes: F24S 70/225 for spectrally selective absorption
• CPC Class Codes: F24S 70/25 Coatings made of metallic material
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y10S 126/908 Particular chemical
• CPC Class Codes: Y10T 428/12611 Oxide-containing component
• CPC Class Codes: Y10T 428/12618 Plural oxides

Abstract

Improved coatings for high temperature solar collectors comprise thermally stable inorganic oxides selected from ferrites, metal oxides and mixtures thereof having solar absorptances greater than 0.9 at wavelengths ranging from about 0.35 to 3.0 microns. The coatings can be applied to a heat transfer surface by painting an organic silicate dispersion of the optically active material onto the substrate and thereafter curing the silicate binder.

Claims

1. In a solar energy collector system of the type operable at temperatures above about 550°

F. including a heat transfer member and wherein means are provided for concentrating incident solar radiation by a factor of from about 40 to 2000 to impinge on said heat transfer member, the improvement comprising a nonselective radiation absorbing surface coating on said heat transfer member, said surface coating being selected from ferrites, oxides of nickel, cobalt, iron, strontium and molybdenum and mixtures thereof having a solar absorptance greater than about 0.90 at wavelengths of from about 0.35μ

to about 3.0μ

.

2. The solar collector system of claim 1 wherein the inorganic oxide is a ferrite.

3. The solar collector system of claim 2 wherein said ferrite has a crystal lattice in which from 1 to 4 different metals are included and said metals are selected from nickel, zinc, lithium, molybdenum, manganese, magnesium, cobalt, copper, strontium, barium, aluminum, gadolinium and yttrium.

4. The solar collector system of claim 2 wherein the ferrite is a nickel-zinc ferrite.

6. The solar collector system of claim 1 wherein the inorganic oxide is an oxide of cobalt.

7. The solar collector system of claim 1 wherein the inorganic oxide is an oxide of iron.

8. The solar collector system of claim 1 wherein the inorganic oxide is an oxide of molybdenum.

5. The solar collector system of claimm 2 wherein the ferrite is a lithium-zinc ferrite.

9. In a solar collector system of the type having light reflector means for concentrating incident solar radiation so as to impinge on a heat transfer member whereby the incident solar radiation is concentrated by a factor of from about 40 to 2000, the improvement comprising:

an inorganic oxide coating on said heat transfer member, said coating having an absorptance greater than about 0.90, at wavelengths from about 0.35 to about 3.0μ and

an emittance greater than 0.45 at wavelengths greater than 3.0μ

, said inorganic oxide being selected from the group consisting of ferrites, oxides of nickel, cobalt, iron, molybdenum and strontium and mixtures thereof.

10. The improvement of claim 9 wherein the metal oxide is an oxide of cobalt.

11. The improvement of claim 9 wherein the inorganic oxide is a ferrite having from 1 to 4 different metals in the crystal lattice and said metals being selected from nickel, zinc, lithium, molybdenum, manganese, magnesium, cobalt, copper, barium, strontium, aluminum, gadolinium, and yttrium.

12. The improvement of claim 11 wherein the ferrite is a nickel-zinc ferrite.

13. The improvement of claim 11 wherein the nickel-zinc ferrite has the composition Ni.sub..35 Zn.sub..65 Fe₂ O₄.

14. The improvement of claim 11 wherein the ferrite is a lithium-zinc ferrite.

15. The improvement of claim 14 wherein the lithium-zinc ferrite has the composition (Li.sub..5 Fe.sub..5)d .9Zn.sub..1 Fe₂ O₄.

16. The improvement of claim 9 wherein the ferrite has the composition (Li.sub..5 Fe.sub..5).sub..45 Ni.sub..175 Zn.sub..375 Fe₂ O₄.

17. The improvement of claim 11 wherein the ferrite has the composition 2CoO·

BaO·

8Fe₂ O₃.