Computational Fluid Dynamic (CFD) Applied to Radiative Cooled Dew Condensers

Abstract

Atmospheric vapour condensation and harvesting is proved to be an alternative or complementary potable water resource in several specific arid or insular geographic areas. Last tests were carried out in Vignola (Corsica Island, France) on small (1 m²) and large scale (30 m²) planar condensers. Nowadays, priority is given to real structures implementation as roofs and very large condensers, or innovative structures with enhanced dew yields like funnel shapes*. The computational fluid dynamic - CFD - software PHOENICS 3.5 has been programmed and applied to the radiative cooled condensers. The sky radiation is integrated and averaged for each structure. The radiative balance is then included in the simulation tool that permits to compare different structures efficiencies: for various meteorological parameters, for complex or simple shapes and for various scales. The program has been validated with experimental data of various pilot systems tested in outdoor. Then, it has been used to precise a 7.32 m2 funnel shape before realization. A 30deg tilted angle was computed to be the best compromise for funnel cooling. Eight months measurements in outdoor tests presented 137.04 % increased dew rate and total collected amount. Max dew amount was 3080 ml in one night, correspondent to a 0.472 mm dewfall. At least, the program will soon be used to expect dew yields of a several thousands square meter condenser implemented in the Kutch (Gujarat, India).