Porous Radiative Cooling Ceramic for Zero-Energy Building Thermal Management
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Solution Overview
Problem
Conventional radiative cooling techniques face limitations such as limited peak emission region, unsatisfactory cooling power, high production costs, and complex manufacturing methods, making them unsuitable for large-scale production and effective energy savings in building cooling systems.
Innovation Solution
A scalable, high-performance passive radiative cooling ceramic (PRCC) with a porous structure and metal oxide composition that reflects solar radiation and emits thermally-generated mid-infrared wavelengths, fabricated using a phase inversion process and sintering method, allowing for zero energy consumption and aesthetic customization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional radiative cooling techniques are used, then cooling effect is achieved, but manufacturing complexity increases and production cost rises
Solution Approach 1:
The patent employs a porous ceramic structure with controlled pore sizes (50 nm-10 μm) and porosity (60%-90%) to achieve high solar reflectivity and mid-infrared emissivity. The porous structure is formed through a simple phase inversion process using polymer spheres as porogens, eliminating complex manufacturing steps while maintaining superior radiative cooling performance
Solution Approach 2:
The patent optimizes key parameters including porosity (60%-90%), pore size distribution (50 nm-10 μm), and sintering temperature (up to 1000°C) to achieve the desired optical properties. By controlling these parameters during a straightforward sintering process, the material achieves high reflectivity in solar spectrum and high emissivity in mid-infrared range without complex fabrication
2Temperature
If conventional radiative cooling techniques are used, then cooling effect is achieved, but production cost increases
Solution Approach 1:
The porous ceramic structure is created through a cost-effective phase inversion process where inexpensive polymer spheres are used as porogens. The process involves simple steps: mixing ceramic powder with polymer solution, drying, and sintering. This eliminates the need for expensive equipment or complex procedures while achieving the required optical performance
Solution Approach 2:
The patent uses inexpensive polymer spheres (such as polystyrene or polyethylene glycol) as temporary porogens that are completely removed during sintering. These disposable porogens enable the creation of porous structures at low cost, making the radiative cooling material economically viable for large-scale production
3Temperature
If conventional radiative cooling techniques are used, then cooling effect is achieved, but emission region becomes limited
Solution Approach 1:
The porous ceramic structure with broad pore size distribution (50 nm-10 μm) enables wideband optical properties. The hierarchical porosity scatters solar radiation across the entire solar spectrum (UV, visible, and near-infrared) and maintains high emissivity across the atmospheric window (8-13 μm), achieving universal radiative cooling performance
Solution Approach 2:
The patent combines ceramic powders (such as alumina, silica, or titania) with porous structure to create a composite material that exhibits both high solar reflectivity and broad mid-infrared emissivity. The composite structure leverages the optical properties of ceramic components while the porous architecture enhances light scattering and thermal radiation across wide wavelength ranges
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 PRCC achieves significant energy savings, reduces greenhouse gas emissions, and provides effective cooling performance with a 3.1-4.9°C temperature reduction compared to conventional tiles, while being environmentally friendly and cost-effective.
Implementation Method 1
The material has a composition such that the layer is configured to reflect, at the exterior face, at least partly of the incoming electromagnetic radiation of at least some wavelengths in the solar spectrum
Implementation Method 2
the layer is further configured to emit thermally-generated electromagnetic emission of at least some mid-infrared wavelengths incident out from the exterior face
Data Source
AI summary
A radiative cooling apparatus including a layer of a material. The layer defines an exterior face. The material has a composition such that the layer is configured to reflect, at the exterior face, at least partly of the incoming electromagnetic radiation of at least some wavelengths in the solar spectrum. The layer is further configured to emit thermally-generated electromagnetic emission of at least some mid-infrared wavelengths out from the exterior face. Ceramics provided by embodiments of the invention could produce extra cooling effect without any electricity consumption, creating a prominent benefit to the energy saving of air conditioning systems of buildings.