Floating Solar Evaporation Structure With Capillary Water Feed
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Solution Overview
Problem
Existing solar-driven evaporation systems face challenges in achieving high efficiency and cost-effectiveness due to heat loss, thermal conductivity, water transport, and material durability, particularly in interfacial evaporation structures.
Innovation Solution
A three-layer floating evaporation structure comprising a water-impermeable thermal insulation layer, a porous absorber layer coated with ultra-black photothermal paint, and an interlocked non-woven cotton fiber layer to enhance water transport and minimize heat loss, using commercially available materials like melamine foam and PVC foam.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If bulk water is heated to high temperature to generate water vapor, then water vapor generation is achieved, but heat loss to bulk water and external environment occurs resulting in slow response to sunlight
Solution Approach 1:
The system segments the water body into bulk water and a thin evaporative layer at the interface. The floating absorber sheet confines heating to only the necessary evaporative layer, preventing heat loss to the bulk water. This segmentation allows rapid response to sunlight while minimizing energy waste.
Solution Approach 2:
The patent applies local quality by concentrating solar absorption properties specifically at the air/water interface where evaporation occurs. The floating absorber sheet with high solar absorptance is positioned only where needed, creating localized high-quality solar absorption without heating the entire water body, thus improving productivity while reducing energy loss.
2Productivity
If interfacial solar-driven evaporation structure is used, then response to sunlight is ultra-fast and thermal efficiency is high, but satisfying all four criteria (solar absorptance, thermal conductivity, water transport, self-floating) simultaneously remains a huge challenge
Solution Approach 1:
The patent employs multi-functional materials that simultaneously satisfy multiple criteria. The floating absorber sheet provides both solar absorption and structural support, while the porous substrate delivers water transport, thermal insulation, and self-floating capability in a single integrated component. This universality reduces device complexity while maintaining high evaporation efficiency.
Solution Approach 2:
The system uses composite material structures combining different properties in one layer. The porous substrate integrates hydrophilic water transport channels with thermally insulating air pockets, while the surface coating provides both solar absorption and structural integrity. These composite materials satisfy multiple performance criteria simultaneously without increasing overall structure complexity.
3Loss of energy
If multilayered structure is proposed with bottom layer serving as heat barrier and water transport medium, then thermal efficiency improves, but under steady working condition macropores are filled with water which is more thermally conductive reducing heat barrier effectiveness
Solution Approach 1:
The patent changes the thermal parameter of the bottom layer by controlling water saturation levels. During operation, the system maintains the porous substrate at optimal moisture content where capillary forces drive water upward without completely saturating the macropores. This parameter control ensures the bottom layer maintains low thermal conductivity while still providing adequate water transport, preventing the trade-off between heat barrier effectiveness and water supply.
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 structure achieves a high evaporation rate of freshwater up to 2.48 kg m−2 h−1 and an efficiency of 172.5% under one sun illumination, with durability and cost-effectiveness, suitable for large-scale desalination and purification.
Implementation Method 1
An ultra-black photothermal paint covers the exposed upper surface of the porous absorber layer to convert solar radiation impinging on the ultra-black photothermal paint into heat for use in generating water vapor from water in the porous absorber layer
Implementation Method 2
the interfacial evaporation should feature a low thermal conductivity, thereby reducing the heat loss from the absorber to the bulk water and localizing the heat at the air/water evaporative interface
Implementation Method 3
an interlocked non-woven cotton fiber layer having a portion thereof between the water impervious insulation layer and the porous absorber layer and one or more additional portions configured to extend to the body of water to act as a capillary-driven pump to transport water from the body of water to the porous absorber layer
Implementation Method 4
the interfacial solar-driven evaporation approach mainly localizes the heat generation at the air/water interface. This method avoids heating a large volume of water
Data Source
AI summary
A floatable interfacial solar-driven evaporation structure includes a water impervious thermal insulation layer adapted to float on a body of water, a porous absorber layer on the water impervious thermal insulation layer, and an interlocked non-woven cotton fiber layer having a portion thereof between the water impervious insulation layer and the porous absorber layer and one or more additional portions configured to extend to the body of water to act as a capillary-driven pump to transport water from the body of water to the porous absorber layer. An ultra-black photothermal paint covers the exposed upper surface of the porous absorber layer to convert solar radiation impinging on the ultra-black photothermal paint into heat for use in generating water vapor from water in the porous absorber layer.