US4074706A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Solar collector having selective film of improved stability to liquid water condensate
Assignee: MacDermid Enthone Inc
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Filing: 1975-07-30
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Granted: 1978-02-21
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Expires: 1995-07-30
Abstract
Abstract Solar collector including a copper or copper alloy base and a selective solar heat energy-absorptive coating or film of improved stability to liquid water on the base. The selective film is characterized by having a solar absorptivity of 0.90 or higher, infrared emissivity no more than 0.20, and a stability such that its selectivity is not significantly reduced after contact with liquid water condensate over a prolonged, cumulative, non-continuous time in excess of 15,000 hours.
Inventors
- 👤 Juan Hajdu
- 👤 Raymond A. Sosnowski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 21:32
CPC Classifications
F; F24; F24S; F24S70/00; F24S70/20; F24S70/25; F24S40/00; F24S40/40; F24S40/42; F24S10/00; F24S10/70; F24S10/75; F24S10/753; F24S70/225; F24S70/60; Y; Y02; Y02E; Y02E10/00; Y02E10/40; Y02E10/44; Y10; Y10S; Y10S126/00; Y10S126/907; Y10S126/908
Claims Analysis
Total Claims: 31
Claim 1
Independent Claim
108 words
A solar collector comprising a base of copper or copper alloy, and a stable, selective, solar heat energy-absorptive coating on the base, said selective solar heat energy-absorptive coating comprising a multiplicity of discrete projections of copper oxide, said selective, solar heat energy-absorptive coating having been rendered stable by contacting the selective, solar heat energy-absorptive coating on the base with a chromic acid solution comprising chromic anhydride (Cr O 3 ) and water for a time sufficient to impart to thee selective coating a stability such that its selectivity is not significantly reduced after contact with liquid water over a prolonged, cumulative, non-continuous time in excess of 1600 hours.
Claim 2
Dependent Claim
108 words
A solar collector comprising a base of copper or copper alloy, and a stable, selective, solar heat energy-absorptive coating on the base, said selective solar heat energy-absorptive coating comprising a multiplicity of discrete projections of copper oxide, said selective, solar heat energy-absorptive coating having been rendered stable by contacting the selective, solar heat energy-absorptive coating on the base with a chromic acid solution comprising chromic anhydride (Cr O 3 ) and water for a time sufficient to impart to thee selective coating a stability such that its selectivity is not significantly reduced after contact with liquid water over a prolonged, cumulative, non-continuous time in excess of 1600 hours.
Claim 3
Dependent Claim
41 words
The collector of claim 1 wherein the selective, solar heat energy-absorptive coating on the base has a solar absorptivity of at least 0.90 and an infrared emissivity no more than 0.20 prior to the stabilizing treatment with the chromic acid solution.
Claim 4
Dependent Claim
39 words
The collector of claim 2 wherein the stability imparted to the selective film is such that its selectivity is not significantly reduced after contact with liquid water condensate over a prolonged, cumulative, non-continuous time in excess of 15,000 hours.
Claim 5
Dependent Claim
30 words
The collector of claim 3 wherein the selective coating is contacted with the chromic acid solution for a time in the range of about 10 seconds to about 60 seconds.
Claim 6
Dependent Claim
17 words
The collector of claim 1 wherein the chromic acid solution comprises sodium phosphate, chromic anhydride, and water.
Claim 7
Dependent Claim
48 words
The collector of claim 5 wherein the chromic acid solution comprises, per each 100 gallons of water, about 1 to about 20 lbs. of a concentrate composition comprising, by weight, about 30 to about 60% of chromic anhydride and about 70 to about 40% of the sodium phosphate.
Claim 8
Dependent Claim
12 words
The collector of claim 5 wherein the sodium phosphate is sodium tripolyphosphate.
Claim 9
Dependent Claim
12 words
The collector of claim 6 wherein the sodium phosphate is sodium tripolyphosphate.
Claim 10
Dependent Claim
26 words
The collector of claim 1 wherein the chromic acid solution comprises about 0.1 to about 5.0 lbs. of chromic anhydride per each 100 gallons of water.
Claim 11
Dependent Claim
29 words
The collector of claim 1 wherein the temperature of the chromic acid solution during the stabilizing contacting treatment is in the range of from room temperature to boiling temperature.
Claim 12
Dependent Claim
30 words
The collector of claim 1 wherein the selective coating is contacted with the chromic acid solution for a time in the range of about 10 seconds to about 60 seconds.
Claim 13
Dependent Claim
87 words
The collector of claim 1 wherein the selective, solar heat energy-absorptive coating on the base is prepared by a process comprising contacting the copper or copper alloy base with a hot aqueous solution comprising an alkali metal chlorite, an alkali metal hydroxide and water at a solution temperature in the range of about 140° F. to about 220° F. for a time sufficient to obtain a selective film on the base having a solar absorptivity of at least 0.90 and an infrared emissivity no more than 0.20.
Claim 14
Dependent Claim
17 words
The collector of claim 12 wherein the chromic acid solution comprises sodium phosphate, chromic anhydride and water.
Claim 15
Dependent Claim
48 words
The collector of claim 13 wherein the chromic acid solution comprises, per each 100 gallons of water, about 1 to about 20 lbs. of a concentrate composition comprising, by weight, about 30 to about 60% of chromic anhydride and about 70 to about 40% of the sodium phosphate.
Claim 16
Dependent Claim
12 words
The collector of claim 14 wherein the sodium phosphate is sodium tripolyphosphate.
Claim 17
Dependent Claim
26 words
The collector of claim 12 wherein the chromic acid solution comprises about 0.1 to about 5.0 lbs. of chromic anhydride per each 100 gallons of water.
Claim 18
Dependent Claim
21 words
The collector of claim 12 wherein the alkali metal chlorite is sodium chlorite and the alkali metal hydroxide is sodium hydroxide.
Claim 19
Dependent Claim
20 words
The collector of claim 17 wherein the chromic acid solution comprises sodium phosphate, chromic anhydride and water as solvent therefor.
Claim 20
Dependent Claim
48 words
The collector of claim 18 wherein the chromic acid solution comprises, per each 100 gallons of water, about 1 to about 20 lbs. of a concentrate composition comprising, by weight, about 30 to about 60% of chromic anhydride and about 70 to about 40% of the sodium phosphate.
Claim 21
Dependent Claim
12 words
The collector of claim 19 wherein the sodium phosphate is sodium tripolyphosphate.
Claim 22
Dependent Claim
24 words
The collector of claim 20 wherein the temperature of the chromic acid solution is in the range of from room temperature to boiling temperature.
Claim 23
Dependent Claim
30 words
The collector of claim 21 wherein the selective coating is contacted with the chromic acid solution for a time in the range of about 10 seconds to about 60 seconds.
Claim 24
Dependent Claim
26 words
The collector of claim 20 wherein the temperature of the chromic acid solution during the contacting is in the range of room temperature to boiling temperature.
Claim 25
Dependent Claim
30 words
The collector of claim 23 wherein the selective coating is contacted with the chromic acid solution for a time in the range of about 10 seconds to about 60 seconds.
Claim 26
Dependent Claim
22 words
The collector of claim 20 having a plurality of metallic tubes adapted to contain heat-transfer fluid in contact with the selective surface.
Claim 27
Dependent Claim
10 words
The collector of claim 25 wherein the fluid is water.
Claim 28
Dependent Claim
22 words
The collector of claim 25 having a layer of thermal insulation material on the side of the base opposite the selective coating.
Claim 29
Dependent Claim
22 words
The collector of claim 25 wherein a sheet of transparent material is retained above the selective surface, and in spaced relationship thereto.
Claim 30
Dependent Claim
25 words
The collector of claim 25 also having the stable, selective, solar heat energy absorptive coating on at least the exposed external surfaces of the tubes.
Claim 31
Dependent Claim
14 words
The collector of claim 25 wherein the tubes are of copper or copper alloy.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-02-20 | 1981-08-22 | 1982-02-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-02-20 | 1985-08-22 | 1986-02-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-02-20 | 1989-08-22 | 1990-02-21 | $7700.00 | Window Closed / Lapsed |