Copper Nanostructure Solar Absorber via Selective Leaching
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Solution Overview
Problem
Current methods for fabricating spectrally selective solar absorbers face challenges in achieving high solar absorptance, low thermal emittance, and superior thermal stability while being cost-effective and scalable, particularly for large-scale production and high-temperature applications.
Innovation Solution
A selective leaching process is used to transform aluminum alloys into plasmonic-nanostructure selective solar absorbers (PNSSAs) with copper nanostructures, utilizing an alkaline solution to dissolve base metal elements and form sponge-like copper nanostructures on the surface, enabling tunable spectral selectivity, high solar absorptance, and low thermal emittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional fabrication methods are used for spectrally selective solar absorbers, then manufacturing complexity and cost increase, but achieving high solar absorptance and low thermal emittance simultaneously becomes difficult
Solution Approach 1:
The invention extracts copper from aluminum alloy substrates through selective leaching using alkaline solutions. The copper ions are dissolved from the alloy and then redeposited to form pure copper nanostructures on the surface, separating the functional copper layer from the aluminum substrate to achieve both ease of manufacture and high spectral selectivity
Solution Approach 2:
The selective leaching process creates porous copper nanostructures with high surface area and controlled porosity. These porous structures enhance light trapping and absorption while maintaining thermal stability, achieving high solar absorptance and low thermal emittance through the porous morphology rather than complex multilayer fabrication
2Use of energy by moving object
If high solar absorptance is achieved through complex nanostructure fabrication, then thermal stability at high temperatures deteriorates
Solution Approach 1:
The invention creates a composite structure where pure copper nanostructures are formed on an aluminum alloy substrate. The copper provides high solar absorptance through plasmonic effects and light trapping, while the aluminum substrate provides thermal stability and structural integrity at high temperatures, combining the advantages of both materials
Solution Approach 2:
The selective leaching process is self-organizing and self-limiting. The alkaline solution automatically penetrates the alloy structure and selectively dissolves aluminum while leaving copper, creating the desired nanostructure morphology without requiring external templating or complex control mechanisms, and the process naturally stops when the protective copper layer forms
3Use of energy by moving object
If pure copper structures are used for solar absorption, then thermal emittance increases, but the invention forms copper nanostructures on alloy substrates to achieve low thermal emittance
Solution Approach 1:
The invention applies different properties to different parts of the structure: the copper nanostructures on the surface provide high solar absorptance through plasmonic resonance and light trapping, while the underlying aluminum alloy substrate provides low thermal emittance and high reflectivity in the infrared range, achieving spectral selectivity through spatial differentiation of material properties
Solution Approach 2:
The invention transitions from bulk copper structures to nanoscale copper structures, changing the dimensional scale to exploit plasmonic effects. The nanoscale morphology provides high surface area for light absorption while the small size prevents bulk copper's high thermal emittance, and the nanostructure geometry can be optimized for both solar absorption and thermal radiation control
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 resulting PNSSAs exhibit high omnidirectional solar absorptance, low thermal emittance, and excellent thermal stability, with photothermal efficiency of up to 85% and cost-effectiveness, suitable for various solar thermal applications including high-temperature systems.
Implementation Method 1
applying an alkaline solution to a surface of the alloy structure to selectively dissolve base metal elements at the surface resulting in fabrication of sponge-like copper nanostructures
Implementation Method 2
Enabled by surface plasmon resonance, this technique forms a copper nanostructured thin film on an alloy mirror, which provides tunable manipulation of the spectral selectivity, high and omnidirectional solar absorptance
Data Source
AI summary
A method is disclosed for producing a plasmonic-nanostructure spectrally selective solar absorber having high solar absorptance, low thermal emittance, and superior thermal stability. The method includes the steps of providing an alloy structure containing a base metal and a copper alloying impurity, wherein copper has a weight percent concentration in the alloy of at least 0.25%; and applying an alkaline solution to a surface of the alloy structure to selectively dissolve base metal elements at the surface resulting in fabrication of sponge-like copper nanostructures on the surface configured to scatter, trap, and absorb light in solar wavelengths.