Thermoacoustic Stack Structure With Low Axial Heat Conduction
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Solution Overview
Problem
Current thermoacoustic systems have low efficiency in converting acoustic energy into thermal energy or vice versa due to undesirable structures and properties of the thermoacoustic energy converting element parts, which limit the effectiveness of energy conversion between acoustic waves and heat.
Innovation Solution
A thermoacoustic energy converting element part with a multilayered structure, featuring through holes with a hydraulic diameter of 0.4 mm or smaller, an open area ratio of 60% or higher, and thermal conductivity along the extending direction of 2 W/m/K or lower, utilizing a first layer with no porosity and a second layer with porosity of 10-50%, made of different materials, and a ceramic coating layer to enhance energy conversion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a thermoacoustic stack with small hydraulic diameter through holes is used, then the contact area between fluid and wall increases improving energy conversion efficiency, but the thermal conductivity increases causing heat loss and reducing temperature gradient
Solution Approach 1:
The patent applies composite materials by combining metal layers (first layer) with ceramic coating layers (second layer) to create a structure with optimized thermal properties. The metal provides structural integrity and acoustic wave transmission, while the ceramic coating provides thermal insulation with low thermal conductivity, thus maintaining temperature gradient while allowing efficient energy conversion through increased contact area via small hydraulic diameter through holes.
Solution Approach 2:
The patent utilizes porous ceramic coating layers with controlled porosity (10-50%) to achieve optimal thermal insulation properties. The porous structure reduces thermal conductivity while maintaining mechanical strength and allowing fluid flow through the through holes, thus enabling efficient heat exchange with the acoustic waves while preventing excessive heat loss.
2Productivity
If the open area ratio of through holes is increased to 60% or higher, then the contact area for heat exchange increases improving energy conversion, but the structural strength decreases
Solution Approach 1:
The composite structure of metal layers combined with ceramic coating layers provides both the required structural strength and the high open area ratio for efficient heat exchange. The metal layers provide mechanical strength while the ceramic coating layers with high open area ratio (60% or higher) maximize the contact area between the fluid and the wall for efficient energy conversion.
Solution Approach 2:
The patent applies local quality by having different layers with different properties: the metal layers provide structural strength and acoustic wave transmission, while the ceramic coating layers provide thermal insulation and high open area ratio for heat exchange. This localized differentiation of material properties allows simultaneous optimization of strength and energy conversion efficiency.
3Loss of energy
If a multilayered structure with alternating porosity is used, then thermal conductivity is reduced improving temperature gradient, but the device complexity increases
Solution Approach 1:
The multilayered composite structure alternates between metal layers (first layer) and ceramic coating layers (second layer) with different porosity values. This alternating structure creates a thermal barrier that reduces thermal conductivity and maintains temperature gradient, while the regular alternating pattern keeps the manufacturing process relatively simple and manageable.
Solution Approach 2:
The patent divides the thermoacoustic energy converting element part into multiple segments or layers, each with specific functions: metal layers for structural support and acoustic wave transmission, and ceramic coating layers for thermal insulation. This segmentation allows each layer to be optimized independently while maintaining overall system simplicity through repetitive alternating patterns.
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 solution significantly improves the efficiency of energy conversion between acoustic waves and heat by increasing the contact area and reducing thermal conductivity, allowing for precise manufacturing and stable temperature gradients, thereby enhancing the conversion process.
Implementation Method 1
the wall extending in an extending direction of the through holes and configured to exchange heat with a fluid in the through holes
Implementation Method 2
a structure of the thermoacoustic energy converting element part has thermal conductivity along the extending direction of 2 W/m/K or lower
Implementation Method 3
The system uses a compression process and an expansion process in a fluid element of a fluid in which acoustic waves travel
Data Source
AI summary
The thermoacoustic energy converting element part includes a plurality of through holes extending along a uniform direction to penetrate a body of the thermoacoustic energy converting element part to form traveling paths of acoustic waves. The element part includes a wall surrounding each of the through holes to extend in an extending direction of the through hole and configured to exchange heat between the fluid. The through hole includes a through hole that has a hydraulic diameter of 0.4 mm or smaller, and an open area ratio of the through holes is 60% or higher. A first layer and a second layer are alternately provided on the wall of the thermoacoustic energy converting element part along the extending direction. A porosity of the first layer is 0% or smaller than a porosity of the second layer. The thermal conductivity of the structure of the thermoacoustic energy converting element part along the extending direction is 2 W/m/K or lower. If a metal plate is provided as the first layer, a plurality of the metal plates having a roughened main surface is layered and bonded by thermocompression bonding to manufacture the thermoacoustic energy converting element part.