Multilayer structure

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Solution Overview

Problem

Conventional radiative cooling techniques fail to achieve sufficient cooling due to solar light interference, resulting in reduced radiative cooling effects within structures, particularly in multilayer structures with translucent base material films that have low infrared transmittance and high visible light transmittance, leading to inadequate cooling of objects inside these structures.

Innovation Solution

A multilayer structure comprising a radiator, a base material layer with high far-infrared transmittance and solar light reflectance, and air layers, where the base material layer includes a region forming an interface with a void or particle structure, enhancing solar light reflection and infrared radiation emission, thereby reducing internal temperature and improving cooling efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If translucent base material films with high visible light transmittance are used, then visibility and natural lighting are improved, but infrared transmittance is low and solar light interference reduces radiative cooling effect

Engineering Contradiction:

Improvevisible light transmittanceVSAvoidradiative cooling effect

Core Design Contradiction:

Illumination intensityVSTemperature

Solution Approach 1:

The base material layer is segmented into multiple layers with different functional characteristics. The first base material layer (31a) has high visible light transmittance for visibility, while the second base material layer (31b) has high solar light reflectance and far-infrared transmittance for radiative cooling. This segmentation allows each layer to specialize in one function, resolving the contradiction between visibility and cooling effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Different regions of the multilayer structure are assigned different optical properties. The first base material layer (31a) is positioned to handle visible light transmission, while the second base material layer (31b) is positioned to handle infrared radiation and solar reflection. This local differentiation of material properties allows simultaneous achievement of visibility and radiative cooling.

Inventive Principle:

Principle #3Local quality

2Temperature

If conventional radiative cooling structures are used, then infrared radiation emission is achieved, but solar light reaches inside the structure reducing cooling efficiency

Engineering Contradiction:

Improveinfrared radiation emissionVSAvoidsolar light interference

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The first air layer (32) acts as an intermediary between the radiator (30) and the base material layers (31). This air layer provides thermal insulation and helps maintain the temperature gradient necessary for effective radiative cooling, while the base material layers filter solar light. The intermediary air layer decouples the infrared emission function from the solar reflection function, allowing both to work effectively together.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Temperature

If high far-infrared transmittance is achieved, then radiative cooling effect is improved, but solar light reflectance must be optimized to prevent heat ingress

Engineering Contradiction:

Improvefar-infrared transmittanceVSAvoidsolar light reflectance

Core Design Contradiction:

TemperatureVSObject-affected harmful factors

Solution Approach 1:

The base material layers are constructed as composite structures with specific material compositions. The second base material layer (31b) uses a composite of resin and inorganic particles (such as TiO2, SiO2, or Al2O3) to achieve both high solar light reflectance and high far-infrared transmittance. This composite material approach allows simultaneous optimization of both optical properties that were previously contradictory.

Inventive Principle:

Principle #40Composite materials

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 proposed multilayer structure effectively reflects solar light and emits infrared radiation, achieving an excellent radiative cooling effect by maintaining the object's temperature below external air temperature, with improved heat insulation and reduced thermal conductivity.

Implementation Method 1

a solar light reflectance A of the multilayer structure and a far-infrared transmittance B of the base material layer satisfy B/(100−A)>7, and a solar light reflectance C of the base material layer is 30% or more

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 2

a far-infrared transmittance B of the base material layer... satisfy B/(100−A)>7

Methodology Applied

Scientific EffectThermal radiation: Thermal Radiation

Implementation Method 3

emits infrared radiation

Methodology Applied

Scientific EffectInfrared radiation: Infrared Radiation

Implementation Method 4

a first air layer that is provided between the radiator and the base material layer

Methodology Applied

Scientific EffectThermal insulation: Thermal Insulation

Data Source

PatentUS11360249B2Multilayer structure

Publication Date: 2022.06.14 FUJIFILM CORP

AI summary

Provided is a multilayer structure including a radiator, a base material layer that includes a region forming an interface in an internal structure, and a first air layer that is provided between the radiator and the base material layer, in which a far-infrared transmittance B of the base material layer and a solar light reflectance A of the multilayer structure satisfy B/(100−A)>7, and a solar light reflectance C of the base material layer is 30% or more.