Diploma Thesis Defense by Mrs Nikoleta Kontaxi
Thesis Title «Radiative Cooling»
Monday April 26 2021, at: 12:00, Venue: : Link Zoom Meeting
- Professor Dionysia Kolokotsa (advisor)
- Professor Mihalis Lazaridis
- Professor Theocharis Tsoutsos
In mid-wavelengths, especially between 8 and 13 μm, the atmosphere of the Earth is extremely transparent in electromagnetic radiation. This wavelength range coincides with the maximum wavelength of thermal radiation from terrestrial structures at typical ambient temperatures. While historically radiative cooling developed to a large extent for night applications, recent work has achieved radiative cooling during the day. In particular, it has been shown that radiative cooling can be achieved under the ambient air temperature, with a photonic structure that reflects almost all the incident sunlight and simultaneously emits significant thermal radiation. Such a structure, which is almost perfect solar reflector, doesn’t make use of incident solar light.
The basic principles of radiative cooling are the almost perfect reflection in the visible spectrum and close to the infrared spectrum (0.3–3 microns) and the high thermal emission in the area of the infrared atmospheric window (8-13 microns). Based on these two basic principles, studies have been conducted using various materials and structures to find the most effective radiant cooling system. In this study, six different photonic structures were designed that can cool a surface which they are placed. Each structure was designed with different materials and thicknesses in order to draw conclusions and decide which is most effective.