Graphene Thermal Management With Isotropic Cladding
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Solution Overview
Problem
The efficiency of heat transfer between a person and thermoelectric devices is diminished by insulating materials, and existing graphene sheets, despite high thermal conductivity, are brittle and require plastic films for strength, which have low thermal conductivity and insulate the graphene.
Innovation Solution
A flexible composite structure is developed, combining a graphene sheet with a highly thermally conductive isotropic cladding that enhances heat transfer in the Z direction and improves the robustness of the graphene, potentially omitting the need for plastic films by using materials like aluminum foil with higher thermal conductivity than the graphene in this direction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If plastic films are bonded to graphene sheets to enhance bending and flexing, then the robustness and flexibility are improved, but the thermal conductivity deteriorates due to the low thermal conductivity of plastic films
Solution Approach 1:
The patent changes the material parameter from plastic film to metal foil, transforming the thermal conductivity property from low to high while maintaining the mechanical support function. The metal foil has thermal conductivity greater than 200 W/mK, compared to plastic film's 0.12-0.30 W/mK, thus resolving the contradiction between flexibility enhancement and thermal conductivity preservation.
Solution Approach 2:
The patent creates a composite structure consisting of graphene sheet material combined with metal foil cladding. This composite material leverages the high thermal conductivity of metal foil in the Z-direction while maintaining the high in-plane thermal conductivity of graphene, achieving both mechanical robustness and superior thermal performance.
2Reliability
If graphene sheets are used to improve heat transfer, then the thermal conductivity is improved, but the brittleness increases requiring additional supportive layers
Solution Approach 1:
The patent introduces metal foil as an intermediary layer that provides mechanical support to the brittle graphene sheets. The metal foil acts as a mediator that absorbs mechanical stress and prevents graphene from breaking, while simultaneously providing a high thermal conductivity pathway in the Z-direction, thus solving both the brittleness and thermal conductivity requirements.
3Ease of operation
If insulating materials are used to provide comfortable contact, then the comfort is improved, but the heat transfer efficiency deteriorates
Solution Approach 1:
The patent changes the thermal conductivity parameter of the contact material from insulating (low conductivity) to highly conductive (metal foil with >200 W/mK). This parameter change allows the material to simultaneously provide comfortable contact through flexibility while maintaining high heat transfer efficiency through superior thermal conductivity.
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 composite structure effectively transfers heat in the X, Y, and Z directions, increasing the thermal contact area and enhancing heat transfer efficiency while maintaining flexibility and strength, thus overcoming the limitations of brittle graphene sheets and insulating plastic films.
Implementation Method 1
The highly conductive isotropic cladding conductively transfers heat in a direction generally aligned with the thickness of the graphene sheet material, such as in the Z direction when referencing the plane of the sheet in the X-Y plane
Implementation Method 2
the graphene sheet material in isolation of each other, the isotropic cladding material is far more conductive in the Z direction
Data Source
AI summary
A heating and cooling device includes a thermoelectric module that is configured to move heat to or from a conductive surface thereof in response to low voltage power applied to the thermoelectric module. A composite structure is configured to conductively transfer heat between the thermoelectric module and the body. The composite structure includes a graphene sheet material that has an interfacing portion that is thermally coupled with and overlaying the conductive surface of the thermoelectric module. A high thermal conductivity isotropic cladding is disposed at least partially over an outlying portion of the graphene sheet material outside of the interfacing portion. The isotropic cladding conductively transfers heat in a direction orthogonal to a planar extent of the graphene sheet material with a higher thermal conductively than the graphene sheet material in this direction.