Remote Coldhead Acoustic Cooling With Resonant Transfer Line
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Solution Overview
Problem
Current high-frequency Stirling and acoustic Stirling coolers face limitations in separating the coldhead and acoustic power source due to the need for short, narrow transfer lines to maintain system resonance and efficiency, restricting their use in applications requiring larger separation distances or reduced vibration.
Innovation Solution
An acoustic cooling device with a coldhead and acoustic power source separated by a long transfer line, optimized to maintain system resonance and efficiency by selecting the tube dimensions and parameters to accommodate a significant fraction of the acoustic wavelength, allowing for remote installation of the coldhead and minimizing vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If the coldhead and acoustic power source are separated by a long transfer line, then the coldhead can be installed in remote locations and vibration at the cold tip is minimized, but the system resonance and efficiency deteriorate due to increased acoustic losses and impedance changes
Solution Approach 1:
The patent applies parameter changes by optimizing the transfer line dimensions (diameter, length, volume) and adjusting the acoustic power source parameters (piston area, stroke, frequency) to compensate for the long transfer line effects. Specifically, the transfer line diameter is increased to reduce acoustic losses, and the piston area is adjusted to maintain proper impedance matching and resonance conditions despite the extended separation distance.
2Loss of energy
If the transfer line diameter is increased to reduce acoustic losses, then the acoustic power loss is minimized, but the volume of the transfer line increases which affects system resonance
Solution Approach 1:
The patent resolves this contradiction by changing the parameter relationships: the transfer line diameter is increased to reduce acoustic losses, but the length is simultaneously optimized and the piston stroke is adjusted to compensate for the increased volume. This multi-parameter adjustment maintains system resonance while minimizing acoustic losses.
3Power
If the piston area is increased to compensate for long transfer line effects, then the pressure wave amplitude is maintained, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies parameter changes by calculating and implementing the specific piston area adjustment needed to compensate for the long transfer line effects. The piston area is increased to maintain proper impedance matching and pressure wave amplitude, with the exact value determined through acoustic analysis to ensure optimal system performance.
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
Enables the use of high-frequency acoustic Stirling coolers in applications with larger separation distances while maintaining performance comparable to unitary systems, by balancing transfer line volume and piston size to reduce acoustic losses and ensure proper resonance and pressure wave amplitude.
Implementation Method 1
The source is usually a pressure wave generator (PWG), including one or more linear motors coupled to pistons that alternately compress and expand the working gas
Implementation Method 2
the dimensions of the tube and the relevant parameters of the acoustic power source are selected to keep the system resonant at the desired drive frequency
Implementation Method 3
the dimensions of the tube and the relevant parameters of the acoustic power source are selected to keep the system resonant at the desired drive frequency
Implementation Method 4
pistons that alternately compress and expand the working gas at the warm end of the coldhead
Data Source
AI summary
An acoustic cooling device is provided. A coldhead and an acoustic power source of the acoustic cooling device are separated by way of a long tube connecting them to enable the cold tip to be installed in a remote location where a traditional unitary system would not fit, would generate too much vibration, or would be otherwise undesirable. The dimensions of the tube and the relevant parameters of the acoustic power source are selected to keep the system resonant at the desired drive frequency (e.g., 60 Hz) and to minimize the impact of the long tube on the system efficiency and capacity.