New architectural forms to increase dew collection

Article issu de "The 7th Conference on Sustainable Development of Energy, Water and Environment Systems, SDEWES Conference, Unesco, Ohrid, République de Macédoine, Juillet 2012"International audienceDew water is water vapour that passively condenses from air. Once properly collected, it can provide a useful supplementary water resource for plants and humans. I ts production can be significantly improved by using specific materials and particular geometry. In this context, new shapes for dew collectors are presented and their water yields are compared with those of a 1 m 2 , 30° , inclined planar condenser used as a standard. The experiments were carried out in Pess ac (SW France), situated about 45 km from the Atlantic Ocean, during summer and fall 2009. In addition to conical shapes, which have 30 % larger yields than the planar reference condenser and whose functioning was simulated numerically, two new families of forms are considered: egg - box and origami types. The egg - box shape yields 9 % more water as compared to the reference planar condenser, a result nearly independent of the dew yield. In contrast, the origami shape gives yields 150 % larger than the referen ce planar condenser for events with high dew volumes and can show 400 % greater yields for low dew volumes. These results are analysed and discussed in terms of (i) radiative effects correlated with the angular variation of sky emissivity, (ii) heat losses by free and forced (wind) air convection and (iii) gravity water flow. General rules to increase dew collection are outlined