Passive radiative cooling during the day
A radiative cooling device can include a reflector positionable to permit operation during daylight hours.
1. A radiative cooling device comprising:
an emitter enclosed in a housing and in thermal communication with atmosphere;
and a reflector mounted on a track suspended above the emitter and capable of being moved along the track to block solar radiation from the emitter.
2. The device of claim 1 , wherein the housing has an opening, the opening having a cover.
3. The device of claim 2 , wherein the cover is partially transparent in an atmospheric wavelength transparency window.
4. The device of claim 3 , wherein the cover is partially transparent in an atmospheric wavelength transparency window and partially reflective in a solar wavelength window, thereby minimizing heat gain due to diffuse solar radiation.
5. The device of claim 3 , wherein the cover includes a nanoporous polyolefin.
6. The device of claim 1 , wherein the emitter is partly absorbing in the solar wavelength spectrum.
7. The device of claim 1 , wherein the emitter is partly reflecting in the solar wavelength spectrum.
8. The device of claim 1 , wherein the reflector is a disc, the disc being positionable to substantially block direct solar radiation from the emitter.
9. The device of claim 8 , wherein the reflector is positioned in a first dimension and a second dimension relative to the emitter based on the location of the sun.
10. The device of claim 1 , wherein the reflector is a band, the band being positionable to substantially block direct solar radiation from the emitter.
11. The device of claim 10 , wherein the reflector is positioned in a first dimension relative to the emitter based on the location of the sun.
12. A method of radiative cooling using the device of claim 1 , the method comprising:
moving the reflector along the track to substantially block direct solar radiation from the emitter.
13. The method of claim 12 , wherein the housing has an opening, the opening having a cover.
14. The method of claim 12 , wherein the cover is partially transparent in an atmospheric wavelength transparency window and partially reflective in a solar wavelength window, thereby minimizing heat gain due to diffuse solar radiation.
15. The method of claim 12 , wherein the cover is partially transparent in an atmospheric wavelength transparency window and partially reflective in a solar wavelength window, thereby minimizing heat gain due to diffuse solar radiation.
16. The method of claim 15 , wherein the cover includes a nanoporous polyolefin.
17. The method of claim 12 , wherein the emitter is partly absorbing in the solar wavelength spectrum.
18. The method of claim 12 , wherein the emitter is partly reflecting in the solar wavelength spectrum.
19. The method of claim 12 , wherein the reflector is a disc, the disc being positioned in a first dimension and a second dimension relative to the emitter based on the location of the sun.
20. The method of claim 12 , wherein the reflector is a band, the band being positioned a first dimension relative to the emitter based on the location of the sun.