
Directional radiation for optimal radiative cooling
Author(s) -
Suwan Jeon,
Jonghwa Shin
Publication year - 2021
Publication title -
optics express
Language(s) - Uncategorized
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.416475
Subject(s) - emissivity , optics , radiative transfer , radiative cooling , zenith , isotropy , thermal radiation , radiance , radiation , omnidirectional antenna , common emitter , materials science , physics , optoelectronics , computer science , antenna (radio) , telecommunications , meteorology , thermodynamics
The omnidirectional radiation scheme has been widely applied to thermal emitters for radiative cooling. We quantitatively illustrate that significant net radiative absorption at high zenith angles limits the performance of such isotropic emitters, and demonstrate that simply cutting off components corresponding to high angles can substantially improve the cooling performance of commonly used isotropic emitter designs. We also present an expression for the ideal directional spectral emissivity at conditions below ambient temperature. As our approach can be applied to coolers with arbitrary surfaces, our results may serve as a basic guideline for designing practical systems with various surfaces, such as rooftops or façades of modern buildings with complicated geometries.