Thin films of high reflectivity for efficient radiative cooling

Yeqing Zhu; Dong Wang; Yong-Hong Ye

doi:10.1117/12.2505995

15 November 2018 Thin films of high reflectivity for efficient radiative cooling

Yeqing Zhu, Dong Wang, Yong-Hong Ye

Proceedings Volume 10964, Tenth International Conference on Information Optics and Photonics; 109643U (2018) https://doi.org/10.1117/12.2505995
Event: Tenth International Conference on Information Optics and Photonics (CIOP 2018), 2018, Beijing, China

Abstract

Passive radiative cooling dissipates heat from Earth into outer space through the atmospheric transparency window (8–13 μm). This technique can be useful for applications in passive building cooling, thermal photovoltaic energy conversion, renewable energy harvesting and passive refrigeration in arid regions. Here we propose a novel design of thermal radiative structure based on one-dimensional (1-D) photonic films which reflects 98.28% of solar radiation while emitting remarkably and selectively in the atmospheric transparency window, where the peak emission reaches 99.5%. Samples are characterized experimentally by using a Fourier transform infrared spectrometer and the experimental results match well with the theoretical ones. The structure can theoretically achieve a temperature reduction of about 50.3 °C from the ambient air temperature without solar radiation and non-radiative heat transfer. Under dry air conditions and assuming non-radiative heat transfer coefficient h_c=6.9 Wm^-2K^-1, it can theoretically achieve a temperature reduction of about 6 °C under direct solar radiation (AM1.5). Without the presence of non-radiative heat transfer, it can cool down 36.3 °C below the ambient air temperature at daytime radiative cooling.

Citation Download Citation

Yeqing Zhu, Dong Wang, and Yong-Hong Ye "Thin films of high reflectivity for efficient radiative cooling", Proc. SPIE 10964, Tenth International Conference on Information Optics and Photonics, 109643U (15 November 2018); https://doi.org/10.1117/12.2505995

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