Pigmented foils for radiative cooling and condensation irrigation

Torbjorn M.J. Nilsson; William E. Vargas; Gunnar A. Niklasson

doi:10.1117/12.185370

9 September 1994 Pigmented foils for radiative cooling and condensation irrigation

Torbjorn M.J. Nilsson, William E. Vargas, Gunnar A. Niklasson

Proceedings Volume 2255, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII; (1994) https://doi.org/10.1117/12.185370
Event: Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, 1994, Freiburg, Germany

Abstract

This paper reports on the development of pigmented polyethylene foils for radiative cooling. The optical properties of the foils were optimized for applications in day-time radiative cooling and water condensation. We first study highly scattering foils used as convection shields. These cover foils combine a high solar reflectance and a high transmittance in the atmospheric window region in the infrared. Different pigment materials were studied and ZnS was the only one that could prevent heating of an underlying blackbody at noon, with the sun in its zenith. A 400 micrometers thick ZnS pigmented polyethylene foil with a pigment volume fraction of 0.15 was tested in Tanzania. At noon the observed temperature of the covered blackbody was only 1.5 K above the ambient. Secondly, we study the potential for condensation of water in an arid region. Pigmented foils for this purpose should combine a high solar reflectance and a high infrared emittance, in order to promote condensation by the radiative cooling effect. Titanium dioxide is a fairly good infrared emitter, but the emittance can be improved by using a mixture of TiO₂ and BaSO₄ pigments or only employing a composite SiO₂/TiO₂. Field tests with a 390 micrometers thick polyethylene foil with TiO₂ and BaSO₄ pigments gave encouraging results.

Citation Download Citation

Torbjorn M.J. Nilsson, William E. Vargas, and Gunnar A. Niklasson "Pigmented foils for radiative cooling and condensation irrigation", Proc. SPIE 2255, Optical Materials Technology for Energy Efficiency and Solar Energy Conversion XIII, (9 September 1994); https://doi.org/10.1117/12.185370

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