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Beysens D.,University Pierre and Marie Curie | Mongruel A.,University Pierre and Marie Curie | Acker K.,OPUR | Acker K.,Sudan University of Science and Technology
Atmospheric Research | Year: 2017

This paper summarizes one year (April 2011 to March 2012) measurements on planar condensing surfaces of dew and rain events and related physico-chemical characteristics in the urban environment of Paris (city center). Yearly collected water was 3.48 mm for dew (63 events) and 593 mm for rain (146 events). The latter value compares well with rain data (547 mm and 107 events) collected within 12 km at Paris-Orly airport. An estimation of dew yield based on meteo data gives 2.35 mm and 74 events, to be compared with 17.11 mm and 196 events at Paris-Orly. These differences highlight the large reduction in dew events and dew yields in an urban area as compared to a close rural-like area. This reduction is not due to a sky view reduction but to heat island that increases air temperature and decreases relative humidity. Analysis of dew (34) and rain (77) samples were done concerning pH, electrical conductivity (EC), major anions and cations as well as selected trace metals and other minor ions. Mean pH values are found similar for both, dew (6.5) and rain (6.1), rain being slightly more acidic than dew. The mean dew total ionic content (TIC 1.8 meq/l) and EC value (124 μS/cm) are about four times that of rain (0.45 meq/l; 35 μS/cm), meaning that total dissolved solids in dew is nearly four times that in rain. Sulfate and nitrate are the most acidifying components, calcium the most neutralizing constituent with ratio of mean total acidity/total alkalinity comparable for dew and rain (~ 0.9). Sulfate and nitrate have mainly anthropogenic sources, whereas chloride and magnesium are mostly connected with marine air masses. Dew is a considerable factor of wet deposition of pollutants; dew and rain ion concentrations, however, meet the WHO requirements for drinking water. © 2017 Elsevier B.V.

Clus O.,Dhomino RD | Lekouch I.,OPUR | Lekouch I.,University Ibn Zohr | Lekouch I.,ESPCI ParisTech | And 8 more authors.
Desalination and Water Treatment | Year: 2013

The coastal region of south Morocco presents a chronically shortage of drinkable and fresh water. In 2007, only 49 mm of rain was recorded. However, measurements in the same year showed that the dew yield was on order of 40% of rain fall. In order to recover dew water in addition to rain water, a small village (Idouasskssou), 8 km from Mirleft and the Atlantic Ocean, was equipped with three pilot condensers of 136 m2 total surface area. A local organization (IMIRJANE) collaborated to ensure a good integration of the project by the village inhabitants. All materials were from local shops. Only the special radiative and hydrophilic coating was coming from non local resources (www.opur.fr). Dew water production during six months, from 15 December. 2008 to 31 July. 2009 (137 dew events, 47% of days) was more than 3,800 L (28 mm, 0.2 mm/dew day). The devices not only condense dew water, they also harvest rain and fog, thus providing to the population a valuable water resource (during fall 2009, the collectors were the only source of water of the village). © 2013 Copyright Balaban Desalination Publications.

Meunier D.,OPUR | Beysens D.,OPUR | Beysens D.,University Pierre and Marie Curie | Beysens D.,CEA Grenoble
Atmospheric Research | Year: 2016

Dwindling supplies of fresh water and climate changes have drawn attention to the need to find alternative sources of water globally. This study examines the potential of the semi-arid region of Baku (Azerbaijan) to exploit in particular dew, but also fog, drizzle and rain water. The Absheron Peninsular suffers from scarceness of water and non-hazardous water sources. Measurements were taken in this region on a 30° inclined plane passive condenser over a year (1/4/2010-31/3/2011) to determine the contribution and validity of using these alternative sources of water. The results show a significant relative contribution from these sources during this period (rain: 84 mm; dew: 15 mm; fog: 6 mm; drizzle: 13 mm). The fact that rain was measured within 23 km from the main station leads to uncertainties in its relative contribution. However, at least for the year under study, there are fair indications that collecting dew, fog and drizzle in addition to rain can significantly increase the collected atmospheric water with value estimated on order 40% ± 20%. © 2016 Elsevier B.V.

Beysens D.,ESPCI ParisTech | Beysens D.,CEA Grenoble | Broggini F.,Agence BlueOfficeArchitecture Bellinzona Suisse | Milimouk-Melnytchouk I.,ESPCI ParisTech | And 2 more authors.
Chemical Engineering Transactions | Year: 2013

Dew water is water vapour that passively condenses from air. Once properly collected, it can provide a useful supplementary water resource for plants and humans. Its 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 m2, 30, inclined planar condenser used as a standard. The experiments were carried out in Pessac (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 reference 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 © 2013, AIDIC Servizi S.r.l.

Beysens D.,University Pierre and Marie Curie | Pruvost V.,OPUR | Pruvost B.,OPUR
Journal of Arid Environments | Year: 2016

We describe a simple method to obtain absolute dew determination in any environment, based on observing dew formed at sunrise on cars. Cars are used as dew condensers where dew yield varies on three different parts that nearly all car exhibits: roof top, windshield and window side. The presence or absence of dew at the sunrise at these particular positions provides an observation scale index n with 4 levels, which is used to quantify dew yield. We show that the index n is proportional to the condensed dew volume h (mm) as measured on a standard planar condenser, inclined 30° from horizontal, following h = Kn. The validation of this scale and the determination of K (=0.067 mm within 20–30% uncertainty) is performed with long term experiments in different areas where dew is observed on several cars, either directly weighted on rooftops or calculated from meteo data. This method can thus be of great help to determine without sophisticated measurements or trained observers the dew potential in many places in the world, in particular in arid and semi-arid environment, where dew can help to answer water demand and means to evaluate the dew potential are often limited or lacking. © 2016 Elsevier Ltd

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