Hydrogel Membrane Conical Structures for Continuous Water Harvesting
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Solution Overview
Problem
Current solar steam generation systems and fog collection technologies face limitations in efficiency and effectiveness, particularly in low solar energy density conditions and are unable to operate continuously, leading to challenges in addressing global water scarcity.
Innovation Solution
Hydrogel membranes with hierarchical three-dimensional microstructures that can capture fog at night and function as interfacial solar steam generators during the day, utilizing tree-shaped conical structures for enhanced fog collection and solar steam generation, achieving high water evaporation rates and daily water collection yields.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If solar steam generation systems are used to purify water by heating and evaporation, then water purification efficiency is improved, but the system can only operate under sufficient solar irradiation and is limited by solar energy density
Solution Approach 1:
The hydrogel membrane is designed to perform multiple functions: during the day it acts as a solar steam generator for water purification, and at night it functions as a fog collector for water harvesting. This multi-functionality allows the system to operate continuously regardless of solar irradiation conditions, resolving the contradiction between purification efficiency and operational flexibility.
Solution Approach 2:
The system achieves continuous water harvesting by switching between solar steam generation during the day and fog collection at night. The hydrogel membrane maintains its water harvesting capability across both operational modes, ensuring continuous useful action without interruption based on solar energy availability.
2Productivity
If polymer mesh materials are used to capture fog, then fog collection is enabled, but efficiency is adversely affected by re-entrainment of deposited droplets and clogging of the mesh
Solution Approach 1:
The hydrogel membrane incorporates localized three-dimensional microstructures (conical protrusions) that create specific surface properties for fog collection. These localized structural features enable efficient droplet capture while preventing re-entrainment and clogging, improving both productivity and reliability simultaneously.
Solution Approach 2:
The conical microstructures on the hydrogel membrane surface provide curved geometries that facilitate droplet coalescence and directional movement. The curved surfaces prevent droplet pinning and promote continuous drainage, eliminating the clogging problem associated with flat polymer meshes while maintaining high fog collection efficiency.
3Productivity
If bio-inspired fog collection motifs are constructed with metals or polymers, then fog collection is achieved, but light-into-thermal energy conversion ability is lacking and incompatibility with solar steam generation occurs
Solution Approach 1:
The hydrogel membrane is a composite material that combines the fog collection capabilities of bio-inspired structures with the solar energy conversion properties of hydrogel polymers. The material integrates both functions, allowing the same structure to collect fog at night and generate thermal energy from sunlight during the day, thus achieving both high fog collection efficiency and compatibility with solar steam generation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The hydrogel membranes enable all-day fresh water harvesting, with a daily yield of up to 34 L/m², improving water collection efficiency and addressing global water scarcity by combining fog collection and solar steam generation capabilities.
Implementation Method 1
At night, the hydrogel membrane may efficiently capture fog droplets and directionally transports them to a storage vessel
Implementation Method 2
Solar steam generation systems of the prior art may utilize sunlight as an energy source to purify saline or contaminated water by directly heating water and driving its evaporation
Implementation Method 3
directly heating water and driving its evaporation at the water-air interface
Implementation Method 4
the conical structures may enable amplification of thermal and fluidic management for interfacial solar steam generation by maximizing light absorption efficiency and guiding vapor escape
Data Source
AI summary
A membrane for water collection may include a sheet having a top surface and a bottom surface, and a plurality of conical structures disposed on the top surface of the sheet, the conical structures comprising a hydrogel material. Each conical structure of the plurality of conical structures may have a height of 1 mm to 50 mm, wherein height is measured from the top surface of the sheet to an apex of a conical structure. Each conical structure of the plurality of conical structures may have an apex angle of 10 to 60 degrees.