Solar receiver with energy flux measurement and control

• US 8,360,051 B2
• Filed: 11/12/2008
• Issued: 01/29/2013
• Est. Priority Date: 11/12/2007
• Status: Expired due to Fees

• Current Assignee: BrightSource Industries (Israel) Ltd (BrightSource Energy)
• Original Assignee: BrightSource Industries (Israel) Ltd (BrightSource Energy)
• Inventors: Gilon, Yoel, Kroyzer, Gil, Hayut, Rotem
• Primary Examiner(s): PRICE, CARL D
• Application Number:
  US12/269,793
• Publication Number:
  US 20090250052A1
• Time in Patent Office: 1,539 Days
• Field of Search: 126/578, 126/573, 126/600, 126/680, 126/684, 126/688, 374/137, 250/203.4, 359/853, 606/418, 606/411.1, 606/411.5
• US Class Current: 126/578
• 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 23/77 with flat reflective plates
• CPC Class Codes: F24S 50/00 Arrangements for controlling solar heat collectors
• CPC Class Codes: F24S 50/20 for tracking
• CPC Class Codes: Y02E 10/40 Solar thermal energy, e.g. solar towers
• CPC Class Codes: Y02E 10/47 Mountings or tracking

Abstract

A solar energy collection system has a solar receiver with an external surface configured for high absorption of light incident thereon. The solar receiver also has a plurality of light-reflecting elements arranged on the external surface. The light-reflecting elements produce at least partially diffuse reflection of light energy incident thereon. Heliostats concentrate solar radiation onto the external surface of the solar receiver. An imaging device provides a digital image of at least a portion of the external surface of the solar receiver. A controller can control the heliostats in response to apparent brightness of the light-reflecting elements as represented in the digital image.

Claims

1. A solar energy collection system comprising:

at least one receiver configured to receive on an external surface thereof reflected solar radiation from heliostats, the at least one receiver housing at least one fluid conveying member for conveying a working fluid therethrough, the external surface having a light-absorbing coating thereon; and

light-reflecting elements disposed on the external surface, the light-reflecting elements producing at least partially diffuse reflection of light energy reflected thereon by the heliostats;

an imaging device for determining the apparent brightness of each of the light-reflecting elements and providing a brightness signal; and

a controller configured to compute a flux distribution across the surface of the at least one receiver responsively to the apparent brightness signal.

2. The solar energy collection system according to claim 1, wherein the light-reflecting elements produce substantially diffuse reflection of light energy reflected thereon by the heliostats.

3. The solar energy collection system according to claim 1, wherein the brightness signal defines an image.

4. The solar energy collection system according to claim 1, wherein the imaging device includes a camera.

5. The solar energy collection system according to claim 1, wherein each of the light-reflecting elements has a uniform, constant and predetermined reflectivity over its surface.

6. The solar energy collection system according to claim 1, wherein the light-reflecting elements are arranged at different locations on the external surface of the at least one receiver.

7. The solar energy collection system according to claim 6, wherein the surface area of the external surface covered by the light-reflecting elements is less than 1% of the total surface area of the external surface.

8. The solar energy collection system according to claim 1, wherein the light-absorbing coating has an absorptivity in the visible light band that is greater than 95% and an emissivity in the infrared band of less than 90%.

9. The solar energy collection system according to claim 1, wherein a ratio of visible light flux reflected by the light-reflecting elements to that reflected by the light-absorbing coating is at least 10 to 1.

10. The solar energy collection system according to claim 1, wherein the light-reflecting elements are painted with a uniform reflective coating.

11. The solar energy collection system according to claim 10, wherein the reflective coating is high-temperature paint with additives for enhanced refraction.

12. The solar energy collection system according to claim 11, wherein the additives include beads.

13. The solar energy collection system according to claim 12, wherein the beads have a diameter less than 50 μ

m.

14. The solar energy collection system according to claim 1, wherein the light-reflecting elements include a diffusively reflective solid.

15. The solar energy collection system according to claim 14, wherein the diffusively reflective solid is mixed in with the light-absorbing coating.

16. The solar energy collection system according to claim 1, wherein the light-reflecting elements include a thread or a tape.

17. The solar energy collection system according to claim 1, wherein the light-reflecting elements include a plurality of threads arranged so as to form a shroud.

18. A solar energy collection system comprising:

a solar receiver having an external surface configured for high absorption of light, the solar receiver also having a plurality of light-reflecting elements arranged on the external surface, the light-reflecting elements producing at least partially diffuse reflection of light energy incident thereon;

a plurality of heliostats configured to concentrate solar radiation onto the external surface of the solar receiver;

an imaging device configured to provide a digital image of at least a portion of said external surface of the solar receiver; and

a controller configured to control the plurality of heliostats in response to the apparent brightness of the light-reflecting elements as represented in the digital image.

19. The solar energy collection system of claim 18, wherein the light-reflecting elements produce substantially diffuse reflection of light energy incident thereon.

20. The solar energy collection system of claim 18, wherein the imaging device includes a camera.