Cryocooler Regenerator Layers for Low Axial Heat Flow
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional cryocooler regenerators experience reduced cooling capacity and effectiveness due to heat flow between the warm and cold ends, as materials with low thermal conductivities often lack adequate volumetric heat capacity.
Innovation Solution
Incorporation of carbon-based anisotropic thermal layers, such as carbon nanotubes or graphene, within the regenerator to reduce axial heat flow while spreading heat radially or laterally, supported by additional layers to enhance structural stability and heat capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If materials with low thermal conductivities are used in the regenerator, then axial heat flow is reduced, but volumetric heat capacity becomes inadequate
Solution Approach 1:
The regenerator uses a composite structure combining carbon nanotubes (or graphene) with a porous substrate material. The carbon-based layer provides low axial thermal conductivity while the porous substrate contributes volumetric heat capacity, allowing the system to simultaneously reduce axial heat flow and maintain adequate heat storage capability.
Solution Approach 2:
The regenerator structure implements different thermal properties in different directions and locations. The carbon-based anisotropic layer specifically targets axial heat flow reduction, while the porous substrate provides radial heat distribution and volumetric heat capacity. This local differentiation of material properties resolves the contradiction between reducing axial conduction and maintaining heat storage.
2Quantity of substance
If conventional porous materials are used in the regenerator, then adequate volumetric heat capacity is achieved, but axial heat flow between warm and cold ends increases
Solution Approach 1:
By combining conventional porous materials with a carbon-based anisotropic layer, the system maintains the volumetric heat capacity benefits of porous materials while adding the low axial thermal conductivity property of carbon nanotubes or graphene. This composite approach allows simultaneous achievement of both requirements.
Solution Approach 2:
The regenerator is segmented into distinct functional layers: a porous substrate layer for heat storage and a carbon-based anisotropic layer for axial heat flow blocking. This segmentation allows each layer to optimize its specific function without compromising the other, resolving the contradiction between heat capacity and axial conduction.
3Loss of energy
If carbon-based anisotropic thermal layers are added to the regenerator, then axial heat flow is reduced and thermal spreading is improved, but device complexity increases
Solution Approach 1:
The use of porous substrate materials provides both structural support and volumetric heat capacity in a single component, reducing the need for additional separate elements. The porous structure naturally facilitates fluid flow while providing thermal energy storage, simplifying the overall design despite the addition of the carbon-based layer.
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
This configuration significantly reduces axial heat transfer while maintaining efficient thermal spreading, improving the overall performance of cryocoolers by up to 37% in terms of efficiency, with the potential for retrofitting existing systems.
Implementation Method 1
each anisotropic thermal layer configured to reduce a flow of heat axially along the regenerator and to spread the absorbed heat radially or laterally in a plane of the anisotropic thermal layer
Implementation Method 2
each anisotropic thermal layer configured to reduce a flow of heat axially along the regenerator
Implementation Method 3
a regenerator configured to transfer heat to a fluid and to absorb heat from the fluid as the fluid flows between a warm end and a cold end of a cryocooler
Implementation Method 4
as the fluid flows between a warm end and a cold end
Implementation Method 5
one or more support layers configured to structurally support one or more of the anisotropic thermal layers
Data Source
Figure 1
Figure 2A~2B
Figure 3~4
AI summary
An apparatus includes a regenerator (112, 212) configured to transfer heat to a fluid and to absorb heat from the fluid as the fluid flows between a warm end (106) and a cold end (108) of a cryocooler (100, 200). The regenerator includes an anisotropic thermal layer (118, 218) configured to reduce a flow of heat axially along the regenerator and to spread the absorbed heat radially or laterally in a plane of the anisotropic thermal layer. The anisotropic thermal layer includes at least one allotropic form of carbon. The anisotropic thermal layer could have a higher radial or lateral thermal conductivity and a lower axial thermal conductivity. The anisotropic thermal layer could include carbon nanotubes (302) and/or graphene (400). The regenerator could include multiple anisotropic thermal layers that divide the regenerator into multiple segments (120, 220), where the anisotropic thermal layers are configured to reduce heat transfer between adjacent segments of the regenerator.