Daytime radiative cooling under a cloudy sky in tropical climate near the equator

Jaesuk Hwang

doi:10.1117/12.3005407

13 March 2024 Daytime radiative cooling under a cloudy sky in tropical climate near the equator

Jaesuk Hwang

Proceedings Volume 12902, Photonic Heat Engines: Science and Applications VI; 1290206 (2024) https://doi.org/10.1117/12.3005407
Event: SPIE OPTO, 2024, San Francisco, California, United States

Abstract

Radiative cooling, taking advantage of the coldness of the sky, has a potential to be a sustainable alternative to meet cooling needs. The performance of a radiative cooling device is fundamentally limited by the emissivity of the sky, therefore depends heavily on the regional weather conditions. Although the sky emissivity is known to increase with the dew point temperature, the feasibility of radiative cooling remains elusive in the equatorial tropical climate, where the weather is humid, cloudy and constantly changing. We point out that a high degree of thermal insulation of the radiative cooling system can be effective under such extreme weather conditions. A new method to characterise dynamic sky conditions is presented, namely to measure the sky window emissivity in the zenith direction. We show that a sub-ambient cooling up to 8 °C is possible during daytime and that the cloud base is not a complete blackbody and can be used as a heat sink for radiative cooling.

Conference Presentation

(2024) Published by SPIE. Downloading of the abstract is permitted for personal use only.

Citation Download Citation

Jaesuk Hwang "Daytime radiative cooling under a cloudy sky in tropical climate near the equator", Proc. SPIE 12902, Photonic Heat Engines: Science and Applications VI, 1290206 (13 March 2024); https://doi.org/10.1117/12.3005407

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