Coating Composition for Heat Gain Reduction
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Solution Overview
Problem
Current passive radiative cooling materials face limitations in practical applications due to sophisticated fabrication processes, hazardous chemicals, and limited cooling temperature achievement, which hinders their widespread use in reducing heat gain, especially in buildings during hot weather.
Innovation Solution
A coating composition comprising TiO2 particles, hollow glass microspheres, and a phosphor material with high quantum yield and excitation wavelength matching TiO2, applied in a polymer matrix to enhance solar reflectance and thermal emission, reducing heat gain by up to 15°C and increasing net cooling power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional passive radiative cooling materials (photonic structures, metamaterials, porous structures, noble metal mirrors) are used, then thermal radiation emission to outer space and solar spectrum reflectance are improved, but fabrication complexity and chemical hazard increase
Solution Approach 1:
The patent changes the material parameters by using common TiO2 particles and hollow glass microspheres instead of complex photonic structures or metamaterials. The coating achieves cooling performance through optimized particle size, concentration, and composition ratios rather than sophisticated fabrication processes.
Solution Approach 2:
The patent replaces expensive and complex fabrication processes with simple, low-cost materials that can be easily applied. The coating uses readily available TiO2 and hollow glass microspheres that can be incorporated into standard painting or coating processes, eliminating the need for hazardous chemical processes and sophisticated fabrication equipment.
2Temperature
If conventional passive radiative cooling materials are used, then cooling temperature is achieved, but the cooling temperature is limited to not more than about 6.0°C under direct sunlight
Solution Approach 1:
The patent creates a composite coating material combining TiO2 particles, hollow glass microspheres, and phosphor material. This composite structure enhances the cooling effect by combining the high solar reflectance of TiO2 with the thermal emission properties of hollow glass microspheres and phosphor, achieving temperature reduction exceeding 6.0°C under direct sunlight.
Solution Approach 2:
The patent optimizes the local distribution and concentration of different materials within the coating. By controlling the particle size and concentration of TiO2, hollow glass microspheres, and phosphor material, the coating achieves enhanced cooling effectiveness in the specific application environment under direct sunlight.
3Power
If TiO2 particles with high quantum yield phosphor material are added to enhance solar reflectance, then net cooling power is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent optimizes the concentration ranges of TiO2 particles (5-20 wt%), hollow glass microspheres (5-15 wt%), and phosphor material (1-5 wt%) to achieve enhanced net cooling power. These parameter optimizations balance performance improvement with manufacturability, avoiding excessive precision requirements.
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 coating composition effectively reduces heat gain by enhancing solar reflectance and thermal emission, achieving a net cooling power increase of about 28 W/m² and infrared emissivity of 0.9 at 8-13 μm, making it suitable for infrastructure, clothing, and automobiles.
Implementation Method 1
high reflectance in the highly intensive solar spectrum (0.3 μm to 2.5 μm)
Implementation Method 2
emit thermal radiation to the extremely cold outer space at a temperature of 3 K through the atmospheric window (8 μm to 13 μm)
Implementation Method 3
a phosphor material having a quantum yield of at least about 90% and an excitation wavelength from about 250 nm to about 440 nm
Data Source
AI summary
A coating composition for reducing heat gain of an article includes TiO2 particles; hollow glass microspheres; a phosphor material having a quantum yield of at least about 90% and an excitation wavelength from about 250 nm to about 440 nm, matching those of the TiO2 particles; and a polymer. Also a method for reducing heat gain of an article by using the coating composition of the present invention.