Dew Collector Research Articles

Atmospheric water harvesting as a sustainable and resilient resource in arid climates: gaining insights from ancient techniques

ABSTRACT Fog and dew, or atmospheric moisture, are valuable complementary resources. Ancient civilisations exploited these resources in harmony with the environment, though information on their techniques is fragmented. This review provides insights into the efficiency, evolution, and relevance of ancient atmospheric water harvesting (AWH) techniques from 5000 B.C. to the 1900s, alongside modern techniques. An analytical framework and assessment are presented to deduce their viability for replication, revival, restoration, or redevelopment. Modern fog collectors yield an average value of 3–10 L/m2/day and dew collectors 0.3–0.6 L/m2/day. Ancient fog collectors from Mexico and Chile resembled modern collectors, while fog drip from trees offers a natural alternative, collecting 70 L/m2/day. The stone drip method shows potential in urban areas with extensive concrete surfaces. Ancient dew collection techniques include alchemists' dew collectors, lithic mulching for soil water conservation, dew ponds for water retention, and stone-pile condensers, which collected up to 360 L/day. Air wells, however, were less effective. Ancient AWH techniques offer valuable insights and can effectively supplement modern collectors, enhancing resilience and water security, especially in arid regions. Implementing AWH techniques provides sustainable, decentralised, nature-based strategies on a micro and macro scale for mitigating contemporary water shortages amidst increasing climate challenges.

Fabrication of arrayed V-shape micro-nano hierarchical structures for dew collection

Planer 2D nanopore arrays of porous anodic alumina can be unfolded to designed 3D arrayed micro-nano hierarchical structures by a programmed anisotropic electrochemical anodization, which consists of programed polymer masking and stepped anodization. Arrayed symmetrical and asymmetrical V-shape tiered micro grooves with nanotip-capped nanopore structures are respectively custom tailored to obtain high-efficiency dew collection. It is found that symmetrical V-shape tiered micro grooves with nanotip-capped nanopore structures show collection efficiency (36.176 ± 3.832 mg cm−2 h−1) twice as much as that of pure nanostructured surface, where the environment temperature is ∼18 °C, the relative humidity is ∼86 % and the sample temperature is ∼5 °C. Owning to the larger dew nucleation area, low solid-liquid adhesion and faster dew growth rate, the jumping micro-dews quickly gather and growth to big dews at the bottom of the V-shape tiers as the samples horizontally placed, which can easily fall off as turn the samples to vertical. Due to the simple equipment, low cost and large-area fabrication ability, these arrayed micro-nano hierarchical structures not only have potential to become high efficiency dew collector but also could be a platform for the controlled preparation of 3D complicated micro-nano structures of various materials with advanced functions.

Bionic collection system for fog-dew harvesting inspired from desert beetle

Obtaining clean water resources from the air is an important method to solve the water shortage problem in arid and semi-arid areas. Improving the efficiency of material water collection from the air remains a huge challenge that needs to be overcome. Inspired by natural creatures, a new combined mist dew collector is proposed. The collecting part of the system has a gradient structure with alternating convexity and endows it with different chemical wettability. Janus sponge will be used as the storage part and mechanically assembled together to form a fog/dew collection system. This combination approach can improve collection efficiency by adjusting the liquid behavior throughout the entire fog collection process, including nucleation of droplets during the capture process, high-speed transmission on conical channels, and separation and storage of droplets from Janus sponge. The synergistic effect of conical capture and sponge separation collection improves the efficiency of fog collection. Compared with traditional fog collection structures, our proposed collection system significantly improves the efficiency of fog collection. Meanwhile, our collection system can effectively collect dew under conventional subcooling conditions. The readily available low-cost raw materials, easy to assemble and disassemble, and easy to carry, our proposed fog/dew collection system combines fog and dew collection as a promising solution to alleviate freshwater shortages in many underdeveloped, arid, and island areas.

Analysis of Architectural Needs for Passive Low-Tech Fog and Dew Collector Building Design: A Narrative Literature Review

Global warming and climate change have negative effects on life on earth. One of the consequences is a water crisis or water scarcity, both in quantity and quality. Indonesia also cannot avoid this problem. Therefore it is necessary to prepare an alternative water supply solution, one of which is from water vapor (atmospheric water), especially in the form of dew and fog. This study aimed to formulate the design requirements for passive low-tech dew and fog collector building by comparing several technologies and projects in the world that have been realized recently that have a relationship with architectural science. This research used qualitative research with a narrative literature review approach. This research produced design requirements in the form of principles and technical requirements in designing and realizing dew and fog collector building, especially in terms of function, construction, and appearance.Keywords: dew collector, fog collector, low-tech, water scarcity, architecture

Thermal regime of semi-natural dew collector’s perspective for afforestation of semi-arid landscapes

Waste rock dumps in the aftermath of pegmatite mining enable the growth of healthy populations of Larix sibirica in, for the forest unsuitable semi-arid steppe habitat, the Khentii Mountains, Mongolia. Trees can thrive in such extreme habitats due to water vapour condensation and adsorption in the topsoil of a dump. During the growing season 2015–2017, continual measurement of thermal regime (hourly) was carried out at the depths of 10, 30 and 60 cm in the dumps and surrounding steppes. At the depth of 10 cm, temperatures (up to 40% of cases) enabling dew formation in dumps, in the time period of the highest possible air humidity (2 a.m. to 8 a.m.) were confirmed there. The suitable temperature conditions to form dew were found primarily at the beginning of the growing season characterized by a low precipitation. Later in the growing season with the following increasing precipitation, the temperature potential of dumps for dew formation decreased continuously. The cross-correlation indicated active exchange of heat between the atmosphere and the dump up to the depth of 30 cm. The outcomes further indicate that water vapour adsorption shall contribute significantly to the moisture regime of dumps and the effective porosity of sandy soils of dumps is likely to form ideal conditions for it. The construction thickness of the cover soil material between the depths of 30 and 60 cm with the predefined physico-chemical properties can be recommended to augment the potential of the dew yield in future projects. Effective water vapour condensation and adsorption may support success of landscape afforestation or reclamation of mining areas in arid or semi-arid conditions. • Thermal regime of waste rock dumps allows water vapour condensation. • Waste rock dumps allow successful growth of trees away from natural forest habitat. • Waste rock dumps represent sustainable solution for reforestation of arid regions.

Comparison of surface foil materials and dew collectors location in an arid area: a one-year field experiment in Kenya

This study characterized different polyethylene (PE) and polyvinyl chloride (PVC) plastic foil materials effectiveness for dew collection in arid field-conditions in Kenya. Dew yields were collected daily for one year. Ten dew collectors with four different plastic foils were setup in the experimental field. The cumulated dew yields ranged from 18.9 to 25.3 mm. The greatest cumulated dew yields were 25.3 mm (nightly mean 0.096 mm) and 24.3 mm (nightly mean 0.093) measured with PVC and OPUR coated collectors respectively. The lowest cumulated dew yields 18.9 mm (nightly mean 0.075 mm) and 19.1 mm (nightly mean 0.074 mm) were measured with PVC and PE coated collectors respectively. Dew provided a continuous water source during the dry season. The type of the surface material was not found to be a determining factor for the collected dew yield. The location of the collector at the experimental field had impact on the collected dew yields. We also compared harvested dew yields to measured meteorological parameters and calculated dew yields with the use of a diffusion model using the measured surface temperatures and coefficient of mass diffusion to evaluate the dew collecting potential under the prevailing conditions.

Dew, Fog and Rain Collector in a Hyper-arid Climate: Case Study in Abu Dhabi

Dew condensers collect dew via thermal radiation and cooling affect without the use of external energy. The aim of this project was to design the 1m x 1m with 30° angle square funnel dew, fog and rainwater collector to calculate the dew yield in Abu Dhabi urban area. In addition, studies were conducted to determine whether the collected dew quantity is significant for practical use and to verify the cooling effect in condenser surface using temperature sensors. Aluminum was chosen as dew collector material due to its high emissivity. Square funnel was chosen as condenser shape due to easiness of the assembly and feasibility of its design. The quantity of the collected water depended on the weather condition. The average collected water was 0.016 ml/day (0.016 mm/m2 /day). Temperature sensor analysis showed that there was a 3.5 °C temperature difference between condenser top and bottom indicating the cooling effect of square funnel shape.

Atmospheric water infiltration intensity in non-rainfall periods under conditionsof varied soil moisture

Abstract The paper presents a function-type relation which demonstrates that volumetric moisture of the surface horizon of soil has an effect on the intensity of atmospheric water infiltration during non-rainfall periods. The relation, developed and then verified on the basis of independent material, reveals that the intensity of infiltration decreases with an increase in volumetric moisture of soil. For the case presented herein, infiltration ceases when volumetric moisture is higher than 0.15 m3 m−3. The developed function also takes into account the effect of atmospheric conditions through the introduction of another argument into the domain. The aforementioned is in the form of potential condensation efficiency measured on a dew collector, and assumes the form of a modified logistic function.

New Architectural Forms to Enhance Dew Collection

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. 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.

Estimating dew yield worldwide from a few meteo data

There is a general need to determine dew yield in any place of the world. However, its determination requires systematic measurements that are not available everywhere. In addition, it depends on the particularities of the dew collector. A simple analytical formula valid for planar dew collectors is elaborated here. It is based on laboratory experiments where it is established that heat loss with surrounding air is the dominant parameter that limits dew condensation. A simple analytical formulation is then derived, which only needs cloud coverage, wind velocity, air and dew point temperature data to be collected, at least once in a day before sunrise. The formulation is tested in several places in the world with different climates. Agreement within typically 30% is found with dew measurements. Such an analytical relationship can thus provide a useful tool to obtain a worldwide estimation of the dew potential.

Produire de l’eau en milieu aride : solutions alternatives issues de l’étude des écosystèmes

Water production in arid surroundings : alternative solutions coming from ecosystems study The scarcity of raw water natural resources for human consumption, global warming and the increasing human population lead to developing alternative solutions to exploit atmospheric water. The observing of ecosystems in arid environments makes it possible to submit various strategies for fog and dew use. Water nets and passive dew collectors are characterized by low production costs, but their productivity remains limited and depends on meteorological conditions. They must be regarded as helper solutions for the most vulnerable populations. Active atmospheric water condensing devices make great autonomous water production possible, if air hygrometry is sufficient. They are to be considered as a major perspective for water production in the future.

Enhanced chemiluminescence as an indicator of air pollution

AbstractInvestigations were conducted to determine the pollution levels of air condensate and rain samples using the enhanced chemiluminescence (ECL) reaction. Air condensate samples were initially collected from roadside sites, non‐roadside sites, smoking‐exposed sites and non‐smoking‐exposed sites using an automatic dew collector. Rainwater was also collected throughout the sampling period. Samples were subsequently analysed using the ECL reaction, and pollution levels (Eclox Units) were calculated. Air condensate samples collected from roadside‐ and smoking‐exposed sites generally had higher pollution levels than those from non‐roadside‐ and non‐smoking‐exposed sites. Samples from both smoking‐exposed and traffic‐exposed sites generally had higher pollution levels than rainwater. Finally, in samples collected from roadside‐exposed sites and rainwater, the main polluting constituents were determined to be cationic/anionic components. In samples collected from smoking‐exposed sites, the main polluting constituents were determined to be organic components.

Passive dew collection in a grassland area, The Netherlands

Passive dew collection experiments were initiated in late 2003 in the centre of The Netherlands within a grassland area. A specially designed 1 m 2 insulated planar dew collector, set at a 30° angle from horizontal, was covered with a thin (0.39 mm) polyethylene foil and subsequently replaced with 4 mm polyvinyl chloride. A second dew collector, in the shape of an inverted pyramid, was constructed to reduce the view angle to only the nighttime sky. A simple surface energy-budget model and an aerodynamic model were used to simulate the dew collected by both collectors. The planar collector collected about 90% of the dew at the grass cover while the pyramid collector collected about 1.20% of the grass cover. The aerodynamic model was able to predict the amount of collector data to within 50% for the planar collector and 60% for the inverted pyramid collector. The pyramid collector design was able to collect about 20% more dew than the inclined planar collector.

Difference in amounts and composition of dew from different types of dew collectors

Dew was collected using several kinds of collectors at the same time, and the composition was compared. The volumes per unit surface areas of dew formed were different based on the types of collectors. It is found that the amounts of the ions, which in part come from gaseous substances, such as organic acids, nitrous acid, etc., per unit area in dew increase with dew volume per unit surface area. On the other hand, chloride, nitrate, sodium, potassium and magnesium which come from only particles showed no variation with the dew volume per unit surface area. These results suggest that the composition of dew varied by the dew volume per unit surface area formed in the different collectors. Dew is usually collected on a polytetrafluoroethylene (PTFE) sheet. The above result suggests that the dew concentration on the PTFE sheet does not represent the real dew concentration on various materials, such as leaves, cars, roofs, road, etc. To determine the real concentration of dew on a material, the material itself has to be usedas a collector. The PTFE sheet could be used as a standard dew sampler forcomparison of dew formed at various places.

Initial experiments on dew collection in Sweden and Tanzania

Moisture in the air can be condensed as dew and used for drinking and irrigation. The radiative cooling properties of polymer foils can enhance the performance of dew collecting surfaces. The main restrictions in condensing water in warm and arid locations are climatic factors, the dew collector design, and the optically selective and adhesive properties of the condensing surface itself. This paper concerns observations of dew formation on radiatively cooled pigmented polyethylene foils. The experiments were carried out in Sweden and in arid Dodoma, Tanzania. The results are in agreement with thermodynamical calculations, though the variation is large in the daily measured dew water volumes. This variation is caused by the hourly and daily changes in wind-speed, cloud cover, dry bulb temperature, and dew point temperature. The results are compared with earlier outdoor observations in Tanzania.

Condensation of water by radiative cooling

Atmospheric humidity can be condensed as dew and used for example in small-scale irrigation. In arid locations, the most favourable conditions for dew collection persist in the late night and around sunrise. We study the possibility to use a dew collector for condensing atmospheric water vapour by exploiting the effect of radiative cooling. In particular, we study pigmented polymer foils with high solar reflectance and high thermal emittance. Suitable pigments are a mixture of TiO 2 and BaSO 4 particles or a novel SiO 2/TiO 2 composite. We calculate the condensation rate under different climatic conditions and report on initial field tests.

On the radiative cooling of a surface during dew formation

From the energy balance of a radiant surface with zero mass and perfectly insulated from below, the equilibrium temperature is calculated as a function of both sensible and latent heat transfer resistance. Under the hypothesis of Robinson,r L=r H is the air in contact with the surface is saturated, the equilibrium temperature is estimated as a function of air temperature, dew temperature and wind speed. This result could be useful to calculate night-time temperature of passive solar collectors or the yield of dew collectors.

Aspects of the occurrence of desert plants

The majority of seedlings in a reg desert in S.E. Morocco are found growing close to stones. Largest numbers are to the west of a stone. The amount and orientation of dip do not affect this pattern. Seedling distribution is discussed in relation to the protection from incident radiation provided by stones, and the possible role of stones as dew collectors.