# US 7,607,428 B2 · Solar absorber > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 7,607,428 B2 - Document ID: US7607428B2 - Status: Granted - Kind: B2 - Application number: 11/573,117 - Filed: 2005-08-05 - Published: 2007-09-13 - Granted: 2009-10-27 - Earliest claimed: 2004-08-05 - Assignees: Schott AG - Inventors: Klaus-Juergen Riffelmann; Thomas Kuckelkorn; Christina Hildebrandt - Web page: https://patentgrep.com/patent/US7607428B2 ## CPC - F24S 10/45: {the enclosure being cylindrical} - F24S 20/20: Solar heat collectors for receiving concentrated solar energy, e.g. receivers for solar power plants - F24S 70/225: for spectrally selective absorption - F24S 80/52: characterised by the material (for preventing heat loss F24S80/56) - Y02E 10/40: Solar thermal energy, e.g. solar towers - Y02E 10/44: Heat exchange systems - Y10S 126/907: Absorber coating - F24S: SOLAR HEAT COLLECTORS; SOLAR HEAT SYSTEMS (for producing mechanical power from solar energy F03G6/00) - Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION - Y10S: TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS ## Abstract The solar absorber is equipped with an absorber body (10) that absorbs incident solar energy (12) and converts it to heat. The absorber body has a selective absorption layer (17) on a side (36) oriented toward the concentrator (13) and another selective absorption layer (18) on an opposite side (38) oriented away from the concentrator (13). The selective absorption layers (17, 18) have threshold wavelengths below which solar radiation is absorbed and above which a reradiation capacity of the absorber body is suppressed. The threshold wavelength of the selective absorption layer (17) on the side (36) of the absorber body that is oriented toward the concentrator is greater than the other threshold wavelength of the other selective absorption layer(18) on the opposite side (38) of the absorber body oriented away from the concentrator. ## Claims ### Claim 1 A solar absorber equipped with an absorber body (10), wherein said absorber body (10) has a side oriented toward a concentrator (13) that concentrates and focuses incident solar energy (12) on the absorber body (10) and an opposite side (38) oriented away from the concentrator (13); wherein a selective absorption layer (17) is provided on said side (36) of the absorber body oriented toward the concentrator (13) and another selective absorption layer (18) is provided on said opposite side (38) of the absorber body oriented away from the concentrator (13); wherein said selective absorption layer (17) on said side (36) oriented toward the concentrator (13) has a threshold wavelength below which solar radiation is absorbed and above which a reradiation capacity of the absorber body is suppressed by the selective absorption layer (17); wherein said another selective absorption layer (18) on said opposite side (38) facing away from the concentrator (13) has another threshold wavelength below which said solar radiation is absorbed and above which said reradiation capacity of the absorber body is suppressed by said another selective absorption layer (18); and wherein said threshold wavelength of said selective absorption layer (17) is greater than said another threshold wavelength of said another selective absorption layer (18). ### Claim 2 (depends on 1) The solar absorber as recited in claim 1, wherein the absorber body (10) is an absorber tube (30). ### Claim 3 (depends on 2) The solar absorber as recited in claim 2, wherein the absorber tube is a steel tube. ### Claim 4 (depends on 1) The solar absorber as recited in claim 1, wherein the absorber body (10) is a porous ceramic body. ### Claim 5 (depends on 1) The solar absorber as recited in claim 1, wherein said selective absorption layer (17) and said another selective absorption layer (18) each have a respective thickness that is less than 10 μm. ### Claim 6 (depends on 5) The solar absorber as recited in claim 5, wherein said respective thickness is less than 200 nm. ### Claim 7 (depends on 1) The solar absorber as recited in claim 1, wherein said absorber body (10) is divided into respective regions (40, 45) with correspondingly different wavelength thresholds for absorption of the incident solar energy. ### Claim 8 (depends on 1) The solar absorber as recited in claim 1, wherein said selective absorption layer (17) has a thickness that is different from that of said another selective absorption layer (18). ### Claim 9 (depends on 8) The solar absorber as recited in claim 8, wherein said another selective absorption layer (18) on said opposite side (38) of the absorber body oriented away from the concentrator (13) is 5 to 20 percent thinner than said selective absorption layer (17) on said side (36) oriented toward the concentrator (13). ### Claim 10 (depends on 1) The solar absorber as recited in claim 1, wherein said selective absorption layer (17) on said side (36) oriented toward the concentrator (13) has a composition that is different from that of said another selective absorption layer (18) on said opposite side (38) of the absorber body oriented away from the concentrator (13). ### Claim 11 (depends on 1) The solar absorber as recited in claim 1, wherein said selective absorption layer (17) and said another selective absorption layer (18) each have at least one cermet layer (26) containing at least one metallic filler, but different amounts of said at least one metallic filler are present in said at least one cermet layer of said selective absorption layer (17) and said at least one cermet layer of said another selective absorption layer (18). ### Claim 12 (depends on 11) The solar absorber as recited in claim 11, wherein said at least one metallic filler comprises chromium, aluminum, copper and/or molybdenum. ### Claim 13 (depends on 11) The solar absorber as recited in claim 11, wherein said at least one cermet layer contains from 20 to 60 percent of said at least one metallic filler.