Microsphere-based coatings for radioactive cooling under direct sunlight

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Solution Overview

Problem

Conventional photonic crystals and solar heat preventive paints face challenges with structural randomness, light scattering inefficiencies, and manufacturing complexities, particularly in achieving effective cooling and light trapping while maintaining cost-effectiveness and applicability on curved surfaces.

Innovation Solution

The development of microsphere-based coatings with tiered structures that incorporate a prescribed degree of randomness and periodicity, allowing for controlled light scattering and absorption, enabling efficient cooling and light trapping through manipulation of light scattering properties in the microsphere media.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If multilayer structures are used to achieve cooling effect, then solar absorption is minimized and cooling performance is improved, but manufacturing complexity increases and precision control is required

Engineering Contradiction:

Improvecooling performanceVSAvoidmanufacturing complexity

Core Design Contradiction:

TemperatureVSDevice complexity

Solution Approach 1:

The patent changes the structural parameters from precise multilayer configurations to random microsphere packings with controlled size distributions. This transforms the manufacturing approach from requiring nanometer-level precision to allowing broader tolerances, while maintaining the cooling function through statistical optimization of scattering properties

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs paint-based coatings with microsphere particles that can be applied using conventional painting techniques rather than precision manufacturing. This approach uses simpler, more cost-effective materials and processes that can be applied to complex geometries without requiring controlled environment fabrication

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

2Illumination intensity

If particle size is increased to enhance sunlight scattering, then scattering efficiency is improved, but coating thickness must be increased

Engineering Contradiction:

Improvesunlight scattering efficiencyVSAvoidcoating thickness

Core Design Contradiction:

Illumination intensityVSLength of stationary object

Solution Approach 1:

The patent creates composite paint formulations containing microsphere particles of specific size ranges (0.5-5 μm) combined with binders and other additives. This composite approach allows the microspheres to provide enhanced sunlight scattering while the binder matrix maintains coating integrity, achieving effective scattering in practical coating thicknesses

Inventive Principle:

Principle #40Composite materials

3Illumination intensity

If high refractive index particles are used to maximize whiteness, then visible light scattering is improved, but near-infrared scattering is weakened causing solar heating

Engineering Contradiction:

Improvevisible light scatteringVSAvoidsolar heating

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

The patent applies the principle of local quality by optimizing particle properties for different spectral regions. The microsphere composition and size distribution are specifically tailored to provide strong scattering across the entire solar spectrum, including near-infrared wavelengths, thereby achieving broad-spectrum reflection that prevents solar heating while maintaining visible whiteness

Inventive Principle:

Principle #3Local quality

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

These coatings achieve a temperature 30-40°C below ambient temperature for passive cooling and enhance energy efficiency in solar cells by simultaneously trapping light and radiating heat, while being cost-effective and suitable for various applications including building construction and electronic displays.

Implementation Method 1

The coating reflects and emits light in a range of 8-13 microns. These coatings achieve a temperature 30-40°C below ambient temperature for passive cooling

Methodology Applied

Scientific EffectLight scattering: Scattering

Implementation Method 2

maximizing heat radiation into an atmospheric window which is mostly within 8-13 μm in light wavelength

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

enhance energy efficiency in solar cells by simultaneously trapping light and radiating heat

Methodology Applied

Scientific EffectLight trapping: Absorption (EM radiation)

Data Source

PatentUS10514215B2Microsphere-based coatings for radioactive cooling under direct sunlight

Publication Date: 2019.12.24 UNM RAINFOREST INNOVATIONS

AI summary

The present prevention provides a surface coating for cooling a surface by light scattering comprising a plurality of successive layers, each of the layers may be comprised of a plurality of spheres arranged to form a structure comprised of packed spheres. Each layer may have a different arrangement of packed spheres to create to a different light scattering property in each of the layers. The coating of the structures may also be formed by randomly packed spheres and the spheres may have a uniform diameter.