Ceramic Thermal Switch with Temperature-Dependent Conductivity
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Solution Overview
Problem
Existing thermal switches require additional components or energy sources for switching, are bulky, and have limited shape flexibility and thermal conductivity variation, making them unsuitable for efficient heat management.
Innovation Solution
A ceramic material with a controlled microstructure characteristic length that changes thermal conductivity with temperature, allowing for self-switching between heat insulation and dissipation states without the need for external components or energy sources.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal switch uses additional components (electrodes, actuators) to switch thermal conductivity, then the switching function is achieved, but the device size increases and shape flexibility is reduced
Solution Approach 1:
The patent extracts and eliminates the additional components (electrodes, actuators, wiring) from the thermal switch system. The core invention uses a transition body material that inherently changes thermal conductivity in response to environmental stimuli, removing the need for external switching components and thereby reducing device size and complexity.
Solution Approach 2:
The transition body material performs self-switching of thermal conductivity based on environmental conditions (temperature, light, moisture) without requiring external control systems. The material autonomously transitions between high and low thermal conductivity states, eliminating the need for actuators and control circuits.
2Reliability
If electronic phase transition materials like VO2 are used to change thermal conductivity, then switching between states is achieved, but the variation in thermal conductivity is small (3.5 to 5.5 W/(m·K))
Solution Approach 1:
The patent employs a transition body material that undergoes significant parameter changes in thermal conductivity (from near-zero to high values) in response to environmental stimuli. This material exhibits a much larger thermal conductivity variation range compared to conventional electronic phase transition materials, enabling effective thermal switching with high contrast between ON and OFF states.
3Reliability
If a thermal switch requires electrodes and wiring to apply energy for switching, then the switching function is achieved, but the switch increases in size and installation positions are limited
Solution Approach 1:
The patent removes electrodes, wiring, and external energy application mechanisms from the thermal switch design. The transition body material responds directly to environmental stimuli (temperature, light, moisture) present in the operating environment, eliminating the need for integrated electrodes and wiring infrastructure.
Solution Approach 2:
The transition body material serves multiple functions simultaneously: it acts as the thermal conduction path, the switching element, and the sensing element. This multi-functionality eliminates the need for separate electrodes, actuators, and control systems, significantly reducing the overall switch size and enabling installation in diverse positions.
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 ceramic material provides effective temperature regulation by switching between low and high thermal conductivity states based on temperature, enabling compact, flexible, and efficient heat management solutions.
Implementation Method 1
a ceramic material having heat-transfer performance that changes with temperatures
Data Source
Figure 1A~1B
Figure 1C~2
AI summary
Provided are a ceramic material having heat-transfer performance that can change with temperatures, and a thermal switch including the same. A ceramic material has a characteristic length La of a micro-structure thereof that satisfies 0.1LAMFP≤La≤100LAMFP, and has thermal conductivity that monotonously increases from room temperature to 100°C, where LAMFP denotes apparent mean free path of phonons at room temperature, and is defined as LAMFP=(3× thermal conductivity)/(heat capacity×speed of sound). The characteristic length La of the micro-structure is an interval between particles of different type of material when the ceramic material includes a composite material in which the different type of material is dispersed in a base material, is an interval between one pore and another pore when the ceramic material includes a porous body, and is the crystalline particle size (interval between one grain boundary and another grain boundary) when the ceramic material includes a polycrystalline body.