Rotating Thermal Diode with Phase Change Materials
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Solution Overview
Problem
Existing thermal diodes, particularly in space and aeronautical applications, face inefficiencies in managing thermal energy when the external environment is not usable for heat dissipation, leading to inadequate preservation of electronic functions and heat dissipation in embedded systems.
Innovation Solution
A thermal diode design featuring concentric rings with alternating thermal insulating and conductive portions, utilizing Phase Change Materials (PCM) and a mechanism for rotational actuation to selectively enable or block heat flow, allowing efficient thermal management through convective and radiative transfer even when the external environment is not a cold source.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a thermal diode uses a mobile conductive element to establish or break thermal connection, then the thermal link can be activated or deactivated, but the thermal efficiency is not satisfactory when the external environment is not suitable for heat dissipation
Solution Approach 1:
The thermal diode is segmented into multiple discrete thermal pathways, each with independent controllable elements (phase change materials, movable conductive elements). This allows selective activation of specific thermal paths based on operating conditions, optimizing heat dissipation efficiency while maintaining reliability.
Solution Approach 2:
The thermal conductivity parameter of the diode is dynamically changed by utilizing phase change materials that alter their thermal properties at specific temperatures. This enables the thermal diode to adapt its heat transfer characteristics to match varying environmental conditions, resolving the contradiction between reliability and energy loss.
2Loss of energy
If the thermal contact with external cold source is maintained, then heat dissipation is enabled, but electronic functions cannot be preserved when external temperature increases
Solution Approach 1:
The thermal diode incorporates dynamic elements including movable conductive components and phase change materials that automatically adjust the thermal connection based on temperature conditions. When external temperature rises, the system dynamically blocks thermal contact to protect electronics; when external temperature is suitable, it dynamically establishes thermal contact for heat dissipation, thus resolving the contradiction between heat dissipation capability and electronic function preservation.
3Reliability
If the thermal diode uses geometrically displaced conductive elements, then thermal response spectrum is larger and more precise, but device complexity increases
Solution Approach 1:
The patent utilizes phase change materials that undergo solid-liquid transitions at specific temperatures to control thermal conductivity. This phase transition mechanism provides precise thermal response at defined temperature thresholds without requiring complex geometric displacements or mechanisms, thereby achieving high thermal response precision while minimizing structural complexity.
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
Ensures guaranteed preservation of electronic functions and efficient heat dissipation by effectively managing thermal inputs and outputs, maintaining acceptable temperatures in embedded systems even under extreme conditions.
Implementation Method 1
a first ring, intended to be in peripheral contact with a housing forming a heat source; the first ring being divided into an even number n of equal angular portions, half of which are made of thermally insulating material over at least part of their thickness and, where appropriate, with a Phase Change Material (PCM) over part of their thickness
Implementation Method 2
which is absorbed by the MCP material filling the spaces between the fins, portions of the finned heat sink
Implementation Method 3
the other half of thermally conductive material, each arranged between two portions of thermally insulating material when n is greater than 2
Implementation Method 4
each comprising a finned heat sink extending radially with respect to the central axis X
Implementation Method 5
no means are implemented to treat the thermal inputs via the shell, whether by convective heat transfer, in the space left free by the mobile conductive element or by radiative transfer over the entire surface of the shell
Data Source
Figure 1A~1B
Figure 2~3A
Figure 3B~3C
AI summary
Thermal diode for thermal bonding between two cylindrical elements. Embedded system comprising such a diode. The invention relates to a thermal diode that can be configured reversibly or irreversibly, consisting of two concentric rings, each in peripheral contact with a cold source (shell) or a heat source (equipment housing), and divided into angular portions with differentiated thermal characteristics. The rings are rotated relative to each other to selectively overlap the angular portions, in order to efficiently transfer or block the heat flux from the heat source.