Thermoacoustic engine
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Solution Overview
Problem
Current thermoacoustic engines face challenges in achieving high conversion efficiency from heat energy to acoustic energy, necessitating optimization of the lengths of the stack, hot heat exchanger, and cold heat exchanger to enhance energy conversion.
Innovation Solution
The thermoacoustic engine design involves a stack with a hot heat exchanger length greater than the stack length and a cold heat exchanger length, where the hot heat exchanger area is smaller than the stack area and equal to the cold heat exchanger area, optimizing the displacement amplitude and temperature gradient to increase heat exchange efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the stack length is increased to enhance conversion efficiency from heat energy to acoustic energy, then the displacement amplitude of the working gas increases, but the overall device length increases and manufacturing complexity increases
Solution Approach 1:
The patent transitions from a conventional stack-only design to a three-component system (stack, hot heat exchanger, cold heat exchanger) arranged in series along the longitudinal direction. This dimensional extension allows the system to achieve enhanced conversion efficiency by distributing thermal processing across multiple components rather than relying solely on increased stack length.
Solution Approach 2:
The patent applies different functional qualities to different components: the stack provides the acoustic resonance cavity, the hot heat exchanger provides localized heating with optimized surface area, and the cold heat exchanger provides localized cooling. Each component is designed with specific length and surface area characteristics tailored to its function, rather than uniformly increasing all dimensions.
2Productivity
If the hot heat exchanger surface area is decreased to optimize displacement amplitude, then the conversion efficiency improves, but the heat exchange capability may be reduced
Solution Approach 1:
The patent optimizes the hot heat exchanger surface area to a specific range (0.003-0.008 m²) rather than simply minimizing or maximizing it. This parameter optimization balances two competing requirements: sufficient surface area for effective heat exchange and limited surface area to maintain appropriate displacement amplitude in the working gas.
Solution Approach 2:
The system dynamically balances heat exchange efficiency and acoustic wave generation by optimizing the hot heat exchanger surface area to a specific range. This allows the system to adaptively achieve both thermal processing effectiveness and acoustic resonance enhancement under operating conditions.
3Temperature
If the cold heat exchanger surface area is increased to improve cooling efficiency, then the temperature gradient increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent divides the thermal management function into separate hot heat exchanger and cold heat exchanger components, each with optimized surface areas. This segmentation allows independent optimization of heating and cooling functions, achieving the required temperature gradient without requiring a single complex heat exchanger design.
Solution Approach 2:
The patent specifies the cold heat exchanger surface area to be substantially equal to the hot heat exchanger surface area (both in the range of 0.003-0.008 m²), creating a balanced thermal system. This parameter matching simplifies the overall design by establishing symmetry between the hot and cold sides, reducing manufacturing complexity while maintaining effective temperature gradient.
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 design enhances the heat exchange efficiency of the hot and cold heat exchangers, leading to improved conversion efficiency from heat energy to acoustic energy, allowing for more efficient collection of heat energy from exhaust sources.
Implementation Method 1
The hot heat exchanger has an internal space for hot heat exchanging communicating with the plurality of flow passages and extending through the hot heat exchanger in the longitudinal direction, and is adapted to heat the working gas in the internal space for hot heat exchanging
Implementation Method 2
The cold heat exchanger has an internal space for cold heat exchanging communicating with the plurality of flow passages and extending through the cold heat exchanger in the longitudinal direction, and is adapted to cool the working gas in the internal space for cold heat exchanging
Implementation Method 3
due to the temperature gradient generated between the both ends in the longitudinal direction of the stack, the working gas thermoacoustically oscillates along the longitudinal direction, thereby generating oscillatory waves (sonic waves) resulting from the longitudinal waves. As a result, acoustic energy (oscillatory energy) is generated inside the thermoacoustic pipe section
Data Source
AI summary
Disclosed are a thermoacoustic engine with high conversion efficiency from heat energy to acoustic energy and a designing method for the thermoacoustic engine. A stack of the thermoacoustic engine has a plurality of flow passages extending through a thermoacoustic piping section. A hot heat exchanger is coupled to one end in a longitudinal direction of the stack. A cold heat exchanger is coupled to the other end in the longitudinal direction of the stack. And a length in the longitudinal direction of the hot heat exchanger is greater than a length in the longitudinal direction of the stack, and is greater than a length in the longitudinal direction of the cold heat exchanger.