scholarly journals Water collection and transport in bioinspired nested triangular patterns

2020 ◽  
Vol 378 (2167) ◽  
pp. 20190441 ◽  
Author(s):  
Bharat Bhushan ◽  
Wei Feng
Keyword(s):  
Pressure Gradient ◽  
Ambient Air ◽  
Travel Speed ◽  
Dew Point ◽  
Water Droplets ◽  
Water Shortages ◽  
Transport Studies ◽  
Triangular Region ◽  
Water Collection ◽  
Proactive Measures

To address water shortages worldwide, proactive measures are needed to supplement the water supply. In arid regions, many plants and animals use fog or the moisture in air as a source of water. An important consideration for efficient water collection is to transport collected water droplets as rapidly as possible to storage/use before they are evaporated. Triangular geometry has been used for faster transport of water droplets. In the case of a triangular geometry, if a droplet is placed at its apex, the droplet is driven across the triangular region by the Laplace pressure gradient. However, the magnitude of the gradient decreases along the triangle. In this study, nested triangles were designed to provide a higher pressure gradient. Water condensation and transport studies were carried out on the nested pattern at a temperature below the dew point in ambient air. It was found that the nested pattern increases the droplet travel speed. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 3)’.

scholarly journals Optimization of bioinspired triangular patterns for water condensation and transport

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190127 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Relative Humidity ◽  
Pressure Gradient ◽  
Surface Temperature ◽  
Dew Point ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Water Condensation ◽  
Water Collection ◽  
Condensed Water ◽  
Droplet Condensation

Water condenses on a surface in ambient environment if the surface temperature is below the dew point. For water collection, droplets should be transported to storage before the condensed water evaporates. In this study, Laplace pressure gradient inspired by conical spines of cactus plants is used to facilitate the transport of water condensed in a triangular pattern to the storage. Droplet condensation, transportation and water collection rate within the bioinspired hydrophilic triangular patterns with various lengths and included angles, surrounded by superhydrophobic regions, were explored. The effect of relative humidity was also explored. This bioinspired technique can be used to develop efficient water collection systems. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals Bioinspired conical design for efficient water collection from fog

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190125 ◽  
Author(s):  
Dev Gurera ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
Laplace Pressure ◽  
Surface Slope ◽  
Water Droplets ◽  
Theme Issue ◽  
Conical Shape ◽  
Gravitational Forces ◽  
Water Collection ◽  
Curvature Gradient ◽  
First Time

Nature is known for using conical shapes to transport the collected water from fog for consumption or storage. The curvature gradient of the conical shape creates a Laplace pressure gradient in the water droplets which drives them towards the region of lower curvature. Linear cones with linearly increasing radii have been studied extensively. A smaller tip angle cone transports water droplets farther because of higher Laplace pressure gradient. Whereas a larger tip angle with a larger surface slope transports water droplets because of higher gravitational forces. In this study, for the first time, a nonlinear cone with a concave profile has been designed with small tip angle and nonlinearly increasing radius to maximize water collection. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

scholarly journals EVAPORATIVE WATER AND AIR COOLERS FOR SOLAR COOLING SYSTEMS. ANALYSIS AND PERSPECTIVES

2017 ◽  
Vol 52 (5) ◽  
Author(s):  
A. Doroshenko ◽  
K. Shestopalov ◽  
I. Mladionov
Keyword(s):  
Systems Analysis ◽  
Ambient Air ◽  
Dew Point ◽  
Cooling Process ◽  
Evaporative Water ◽  
Cooling Systems ◽  
Solar Cooling ◽  
Multistage System ◽  
Process Implementation ◽  
Polymeric Structures

The concept of evaporative coolers of gases and fluids on the basis of monoblock multichannel polymeric structures is presented. Different schemes of indirect evaporative coolers, in which the natural cooling limit is the dew point of the ambient air  are discussed. In such systems the cooling temperature is lower than the wet bulb temperature of the ambient air. Special attention is paid to the recondensation of water vapor for deep evaporative cooling. It is shown that for the solution of the recondensation problem it is necessary to vary the ratio of the contacting air and water flows, particularly in each stage of the multistage system. Recommendations for the deep cooling process implementation in the evaporative coolers of gases and liquids are given.

scholarly journals Gender and Community Mainstreaming in Fog Water Collection Systems

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1472 ◽  
Author(s):  
Kayla Lucier ◽  
Manzoor Qadir
Keyword(s):  
Sustainable Development ◽  
Water Shortages ◽  
Fog Water ◽  
The Sustainable Development ◽  
Social Burden ◽  
Water Collection ◽  
Primary Water ◽  
Women And Girls ◽  
Water Scarce ◽  
Fog Water Collection

Fog water collection is an emerging opportunity to combat local water shortages in water-scarce areas where sustainable access to water is unreliable, but fog events are frequent. Since fog water systems are implemented within or near communities, they eliminate or decrease the need to travel far distances for the collection of water during times of scarcity. As a result, these systems decrease the physical and social burden of water collection on women and girls, who are the primary water gatherers in most traditional communities. This is an important outcome because women and girls are disproportionately affected by water scarcity and are not seen as equals in water management, access, or control. This paper illustrates how several fog water collection projects have shown, empirically, that the positive outcomes for women and girls may include the freeing of time for domestic and educational pursuits, improved health outcomes, and improved perceptions of self and others’ perceptions of women. These findings are important at a time when the world at large is addressing the Sustainable Development Agenda, where Sustainable Development Goal (SDG) 6 necessitates safe water and sanitation for all and SDG 5 ensures gender equality to empower all women and girls.

scholarly journals Bioinspired triangular patterns for water collection from fog

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190128 ◽  
Author(s):  
Dong Song ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
Science And Technology ◽  
Laplace Pressure ◽  
Theme Issue ◽  
Droplet Motion ◽  
Triangular Shape ◽  
Conical Shape ◽  
Bioinspired Materials ◽  
Water Collection ◽  
Curvature Gradient

Cacti use spines with conical geometry to transport water to its base. A conical shape with curvature gradient generates a Laplace pressure gradient along the droplet, which is responsible for droplet motion. In this study, the triangular shape was used which also generates a Laplace pressure gradient along the droplet. A bioinspired surface, composed of a hydrophilic triangular pattern surrounded by a rim of superhydrophobic region, was used to transport water collected from the fog on the hydrophilic pattern. The growing droplets start to coalesce into bigger ones. Eventually, they are big enough to touch the superhydrophobic borders, which trigger the transport motion. Droplet mobility and water collection measurements were made on triangular patterns with various geometries to determine the most efficient configurations. Results from this study can be used to enhance the performance of water collection systems from fog. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

An Integral Approach to Designing of an Optimized and Reliable Anti-Icing System Under Off-Design Operating Regimes in a Gas Turbine

2019 ◽  
Author(s):  
Nishit Mehta ◽  
Olga Altukhova ◽  
Abdul Nassar ◽  
Leonid Moroz
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Ambient Air ◽  
Operating Conditions ◽  
Dew Point ◽  
Integral Approach ◽  
Air Supply ◽  
Compressor Work ◽  
Flow Blockage ◽  
Operating Regimes

Abstract Anti-icing systems (AIS) are used in aviation and in ground gas turbines operating in humid climates where relative humidity is above 80% with mist and the temperature of the intake air drops to 5°C and below. Ice formation can disrupt the compressor work by causing vibrations, inlet flow blockage or even a surge in some cases. An anti-icing system is activated in such cases to heat the inlet air before it reaches the compressor. The objective of this work is to design and study an anti-icing system (AIS) for different ambient air parameters and different gas turbine modes of operation. A particular climatic situation (Saint-Petersburg, Russia) is considered as the basis for assessing the suitability of different anti-icing systems and to choose the best configuration out of different possible arrangements. The present work is divided in three major tasks. The first task involves the choice of the anti-icing system arrangement. The second task is to design the heating air supply system by determining the geometric sizes of bypass pipeline with fully open damper to ensure conduction of required air flow at the anti-icing system design condition. In the final task, the entire process is integrated and automated to calculate multiple iterations for different gas turbine operating regimes to assess the reliability of the designed anti-icing system at all operating conditions of the gas turbine. Such assessment is critical as it helps to identify the operating conditions at which the designed anti-icing system would not be able to heat the intake air to a certain temperature above the dew point temperature.

Directed motion of water droplets on multi-gradient photopolymer surfaces

2019 ◽  
Vol 10 (15) ◽  
pp. 1882-1893 ◽  
Author(s):  
E. Rossegger ◽  
D. Hennen ◽  
T. Griesser ◽  
I. Roppolo ◽  
S. Schlögl
Keyword(s):  
Pressure Gradient ◽  
Laplace Pressure ◽  
Water Droplets ◽  
Directed Motion ◽  
Directional Movement

Rapid and directional movement of water droplets across a photopolymer surface with inscribed wettability and Laplace pressure gradient is demonstrated.

scholarly journals Water droplet dynamics on bioinspired conical surfaces

2019 ◽  
Vol 377 (2150) ◽  
pp. 20190118 ◽  
Author(s):  
Charles T. Schriner ◽  
Bharat Bhushan
Keyword(s):  
Pressure Gradient ◽  
High Water ◽  
Laplace Pressure ◽  
Conical Surface ◽  
Human Consumption ◽  
Droplet Dynamics ◽  
Water Collection ◽  
Droplet Movement ◽  
Movement Distance ◽  
Conical Surfaces

Cacti use the Laplace pressure gradient due to conical geometry as a mechanism for collecting water from fog. Bioinspired surfaces using conical geometry can be developed for water collection from fog for human consumption. A systematic study is presented which investigates the dynamics of water droplets on a bioinspired conical surface. A series of experiments was conducted where a known volume of droplets was deposited on the cone. This was followed by an investigation into droplet dynamics where the droplets are deposited from fog and the volume is unknown. This includes a study on the macroscopic level as well as the microscopic level. The main parameters that were varied for these tests were the tip angle and the cone orientation. The droplet movement observed was compared relatively. Based on captured videos of droplet movement, distance travelled and velocities were measured. The Laplace pressure gradient, gravity and droplet coalescence were found to be the mechanisms of droplet movement on a conical surface. The findings of this study should be of interest in designing bioinspired surfaces with high water collection. This article is part of the theme issue ‘Bioinspired materials and surfaces for green science and technology (part 2)’.

The Potential of Night Sky Radiation for Humidity Control

2015 ◽  
Author(s):  
Zachary Springer ◽  
M. Keith Sharp
Keyword(s):  
Storage Capacity ◽  
Volume Flow Rate ◽  
Ambient Air ◽  
Dew Point ◽  
Weather Data ◽  
Cooling Load ◽  
Floor Area ◽  
The Us ◽  
Night Sky ◽  
Mountain West

Ambient energy sources, including ambient air, ground and night sky, have potential for space cooling. The night sky offers the lowest temperature and, therefore, the greatest potential across most of the US. Compared to a previous analysis that considered only the sensible cooling load, the objective of this new project was to evaluate the potential of night-sky radiation (NSR) to also serve the latent cooling load. ASHRAE standard 55 was used to establish the comfort limits (22°C for room temperature and 60% relative humidity). Condensation was evaluated as the mechanism for humidity reduction, thus the dew-point temperature, 13.9°C, corresponding to the ASHRAE limits was the maximum target temperature for night-sky cooling. Typical meteorological year (TMY3) weather data was used for eleven locations representing ASHRAE climate zones. Building heat gain, infiltration/ventilation requirements and night-sky radiator size were characterized by a load-to-radiator ratio LRR defined as the infiltration/ventilation volume flow rate times the ratio of building floor area to radiator area. Three values of LRR were evaluated: 0.35, 3.5 and 35 m/hr. Three thermal storage cases were considered: 1. Annual NSR cooling potential (seasonal storage), 2. Diurnal storage, and 3. The minimum storage capacity to serve the entire annual load, as well as the effects of capacity less than the minimum. To evaluate the effect of night-sky radiator temperature on storage capacity, six NSR temperatures Trad = 13.9 to −26.1°C were tested. Results showed that even in Miami, FL (the most challenging climate evaluated), annual NSR potential exceeded the total sensible and latent cooling load, at least for the lowest LRR and highest Trad. For diurnal storage, NSR could serve less than 20% of the load in the hot and humid southeast, but the entire load in the mountain west. The minimum storage capacity to meet the entire annual load corresponds to the capacity required to bridge the span of time without NSR availability during which the largest cooling load occurs. This capacity decreases with decreasing LRR and decreasing Trad. For the southeast, large capacity is required, but for Louisville, for instance, sufficient capacity is provided by the equivalent of as little as 0.05 m of water over the floor area of the building for LRR = 0.35 m/hr. These results demonstrate that for much of the US, night-sky radiation has the potential to serve the entire annual sensible and latent cooling load.

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