Series Pulse Tube Layout for Three-Stage Cryocooler Simplification
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Solution Overview
Problem
Existing cryorefrigeration devices, such as Stirling and Gifford-McMahon regenerative cryocoolers, suffer from noise, vibration, and frequent maintenance due to mechanical displacers, while pulse tube cryocoolers lack efficient multi-stage designs for achieving low temperatures.
Innovation Solution
A three-stage pulse tube cryocooler design where the third stage pulse tube is arranged below the second stage, with a gas flow conduit between the second stage pulse tube heat exchanger and the cold end of the second stage regenerator, allowing gas expansion and refrigeration, reducing the number of moving parts and maintaining a simpler structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If multi-stage pulse tube cryocoolers are designed with separate parallel pulse tubes for each stage, then cooling performance at multiple temperature levels is achieved, but device complexity and number of moving parts increase
Solution Approach 1:
The patent combines the second and third stage pulse tubes into a single integrated pulse tube structure, where the second stage and third stage operate in series within the same tube. This merging reduces the total number of pulse tubes from three (in conventional parallel designs) to two, simplifying the overall device structure while maintaining three-stage cooling capability through strategic placement of regenerators and heat exchangers at different positions along the tube.
Solution Approach 2:
The single pulse tube serves multiple functions by accommodating both second stage and third stage cooling operations simultaneously. The tube functions as both a second stage pulse tube (with its own regenerator and cooling station) and a third stage pulse tube (with a separate regenerator and cooling station), eliminating the need for separate dedicated tubes for each stage and reducing system complexity.
2Productivity
If conventional three-stage parallel pulse tube cryocoolers are used, then adequate cooling capacity is provided, but vibration and acoustic noise increase
Solution Approach 1:
By merging the second and third stage pulse tubes into one, the patent reduces the number of independent oscillating systems from three to two. This reduction in the number of pulsing components directly decreases the overall vibration and acoustic noise generated by the cryocooler, while the series arrangement ensures that cooling capacity is maintained through efficient heat extraction at multiple stages.
3Temperature
If more pulse tubes and components are added to achieve three-stage cooling, then lower temperatures are achieved, but maintenance requirements increase
Solution Approach 1:
The integration of second and third stages into a single pulse tube reduces the total component count, particularly eliminating redundant orifices, passages, and connection points. Fewer components mean fewer potential failure points and less frequent maintenance requirements, while the series configuration ensures that each stage contributes to achieving the target low temperature of approximately 4K.
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 achieves lower temperatures with reduced vibration and noise, increased maintenance intervals, and improved reliability by arranging the second and third stages in series with a gas flow passage, enabling intermediate temperature connections for diverse cooling applications.
Implementation Method 1
Pulse tube cryocoolers operate by cyclically compressing and expanding a working fluid in conjunction with its movement through heat exchangers. Heat is removed from the system upon the expansion of the working fluid in the gas phase.
Implementation Method 2
Single stage pulse tube cryocoolers are generally capable of reaching temperatures above 20K., and achieving lower temperatures has in the past required staging of the pulse tubes
Implementation Method 3
Heat is removed from the system upon the expansion of the working fluid in the gas phase.
Data Source
AI summary
A three-stage pulse-tube cryocooler, in which the third stage pulse tube is arranged below the second stage pulse tube, with a gas flow conduit between the second stage pulse tube heat exchanger and the cold end of the second stage regenerator. The design of the invention is much simpler than a conventional three-stage parallel pulse tube cooler, requiring only two pulse tubes at the warm (room temperature) end and two reservoirs, with a corresponding reduction in the number of associated orifices, passages, etc. In effect, this provides a three stage cryocooler with a two-stage warm end design by putting the second and third stage pulse tubes in series, with a gas flow passage providing gas flow between the second and third stages for gas expansion and refrigeration. The three-stage design allows an intermediate temperature connection between the temperatures of the first and third stages, for applications which require three cooling temperatures.