Panel for selectively absorbing solar thermal energy and the method of producing said panel

• US 3,920,413 A
• Filed: 04/05/1974
• Issued: 11/18/1975
• Est. Priority Date: 04/05/1974
• Status: Expired due to Term

• Current Assignee: James R. Lowery
• Original Assignee: James R. Lowery
• Inventors: Lowery, James R.
• Primary Examiner(s): Mack, John H.
• Assistant Examiner(s): Weisstuch, Aaron
• Application Number:
  US05/458,484
• Time in Patent Office: 592 Days
• Field of Search: 204/40,42 29/194,197,195,197.5 126/270
• US Class Current: 428/629
• CPC Class Codes: C09K 5/00 Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
• CPC Class Codes: C25D 3/562 containing more than 50% by weight of iron or nickel or cobalt
• CPC Class Codes: C25D 3/565 containing more than 50% by weight of zinc
• CPC Class Codes: C25D 5/12 at least one layer being of nickel or chromium
• CPC Class Codes: C25D 5/44 Aluminium
• CPC Class Codes: C25D 5/627 Electroplating characterised by the visual appearance of the layers, e.g. colour, brightness or mat appearance
• 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: Y10S 205/923 Solar collector or absorber
• CPC Class Codes: Y10S 428/926 Thickness of individual layer specified
• CPC Class Codes: Y10T 428/1259 Oxide
• CPC Class Codes: Y10T 428/12792 Zn-base component

Abstract

A panel for selectively absorbing solar thermal energy comprising a metallic substrate, a layer of bright metallic material carried on the substrate, and a solar thermal energy absorbing coating carried on the bright metallic material. A layer of zinc is interposed between the metal substrate and the layer of bright material or the metallic substrate can be anodized for receiving the layer of bright metallic material. Also disclosed is the method for producing the coating which selectively absorbs solar thermal energy.

Claims

1. A METHOD FOR PRODUCING ON A METALLIC SUBSTRATE A COATING WHICH SELECTIVELY ABSORBS SOLAR THERMAL ENERGY, WHICH COMPRISES THE STEPS OF CLEANING THE METALLIC SUBSTRATE, PREPARING SAID METALLIC SUBSTRATE TO RECEIVE A BRIGHTENING LAYER OF BRIGHT NICKEL, ELECTROPLATING THE BRIGHTENING LAYER OF BRIGHT NICKEL TO SAID METALLIC SUBSTRATE, AND APPLYING A SOLAR THEMAL ENERGY ABSORBING COATING OF BLACK NICKEL TO SAID BRIGHT NICKEL BRIGHTENING LAYER, SAID BLACK NICKEL COATING BEING APPLIED BY ELECTROPLATING AT ROOM TEMPERATURE FROM AN AQUEOUS BATH CONTAINING NICKEL (II) SULFATE HEXAHYDRATE, BICKEL (II) AMMONIUM SULFATE HEXAHYDRATE, ZINC SULFATE HEPTAHYDRATE AND SODIUM THIOCYANATE AT A PH FROM ABOUT 5.6 TO ABOUT 5.9 AND A CURRENT DESITY BETWEEN ABOUT 0.5 AND ABOUT 4.0 AMPERES PER SQUARE FOOT, SAID BLACK NICKEL COATING BEING BETWEEN 800 AND 5,000 ANGSTROMS IN THICKNESS WHEREBY THE RESULTING COATED METALLIC SUBSTRATE HAS A SOLAR ABSORPTANCE (A) OF AT LEAST 0.90 AND A THERMAL EMISSIVITY ($) NOT EXCEEDING 0.06.

2. The method as set forth in claim 1 wherein said metallic substrate is aluminum, said metallic substrate being prepared to receive said brightening layer by anodization in an aqueous solution containing phosphoric acid, said brightening layer being applied by electroplating from an aqueous bath containing at least nickel (II) sulfate hexahydrate, a nickel (II) chloride hexahydrate and boric acid at a current density from about 15 to 25 amperes per square foot at a bath temperature from about 120* to about 140* F to produce a coating from about 0.00025 to about 0.00075 inches in thickness.

3. The method of claim 1 wherein said metallic substrate is aluminum and said metallic surface is prepared to receive said brightening layer by applying an immersion layer of zinc.

4. A PANEL FOR ABSORBING SOLAR THERMAL ENERGY COMPRISING:

AN ALUMINUM SUBSTRATE;

A LAYER OF BRIGHT NICKEL CARRIED ON SAID SUBSTRATE;

A SOLAR THERMAL ENERGY ABSORBING COATING OF BLACK NICKEL CARRIED ON SAID BRIGHT NICKEL DISTAL FROM SAID METALLIC SUBSTRATE;

SAID BLACK NICKEL COATING BEING BETWEEN 800 ANGSTROMS AND 5,000 ANGSTROMS IN THICKNESS;

SAID PANEL HAVING A SOLAR ABSORPTANCE (A) OF AT LEAST 0.90 AND A THERMAL EMITTANCE ($) LESS THAN ABOUT 0.06;

A LAYER OF ZINC BEING INTERPOSED BETWEEN SAID ALUMINUM SUBSTRATE AND SAID LAYER OF BRIGHT NICKEL MATERIAL.

5. A panel for absorbing solar thermal energy comprising:

a metallic substrate;

a layer of bright nickel carried on said substrate;

a solar thermal energy absorbing coating of black nickel carried on said bright nickel distal from said metallic substrate;

said black nickel coating being about 1,500 angstroms in thickness;

said panel having a solar absorptance ( Alpha ) of at least 0.90 and a thermal emittance ( epsilon ) less than about 0.06.

6. A panel for absorbing solar thermal energy comprising:

an aluminum substrate;

a layer of bright nickel carried on said substrate;

a solar thermal energy absorbing coating of black nickel carried on said bright nickel distal from said metallic substrate;

said black nickel coating being between 800 angstroms and 5,000 angstroms in thickness;

said panel having a solar absorptance ( Alpha ) of at least 0.90 and a thermal emittance ( epsilon ) less than about 0.06;

said aluminum substrate being anodized for receiving said layer of bright nickel.