Pulse Tube Refrigerator Flow Layout for 77 K Cooling Capacity
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Solution Overview
Problem
Current Stirling pulse tube refrigerators have limitations in refrigerating capacity, particularly in achieving efficient cooling at low temperatures due to suboptimal design configurations that affect heat exchange efficiency.
Innovation Solution
The design incorporates a low temperature heat exchanger with a gas flow passage and a flow straightener separated by a short connecting passage, ensuring uniform gas flow and improved heat exchange efficiency, with the flow straightener and gas flow passage spaced apart by no more than 10% of the pulse tube length to enhance refrigerating capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the flow straightener is placed close to the low temperature heat exchanger, then the heat exchange efficiency is improved, but the gas flow uniformity deteriorates
Solution Approach 1:
A connecting passage is introduced as an intermediary element between the flow straightener and the low temperature heat exchanger. This passage allows the gas flow to be further stabilized after passing through the flow straightener, ensuring uniform flow distribution into the heat exchanger while maintaining close proximity for efficient heat exchange.
Solution Approach 2:
The flow straightener is positioned to pre-condition the gas flow before it enters the connecting passage and subsequently the low temperature heat exchanger. This preliminary straightening action, combined with the connecting passage design, ensures that the gas flow is uniformly distributed before heat exchange occurs, resolving the contradiction between proximity for efficiency and distance for uniformity.
2Stability of the object's composition
If the connecting passage length is increased, then the gas flow uniformity is improved, but the refrigerating capacity deteriorates
Solution Approach 1:
The length of the connecting passage is optimized to a specific parameter range (10-50mm) representing a critical balance point. This parameter change ensures sufficient length for flow uniformity while maintaining short enough distance to preserve refrigerating capacity, resolving the contradiction between these two requirements.
3Stability of the object's composition
If the flow straightener and gas flow passage are spaced apart, then the gas flow uniformity is improved, but the heat exchange efficiency deteriorates
Solution Approach 1:
The connecting passage serves as a mediator that bridges the spatial gap between the flow straightener and the low temperature heat exchanger. It maintains a controlled distance that allows flow uniformity to develop while minimizing the impact on heat exchange efficiency through its dimensional optimization.
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 increases refrigerating capacity by approximately 1.6 times, achieving efficient cooling at 77 K, as demonstrated by experimental results, while maintaining a compact and efficient design.
Implementation Method 1
a flow straightener that is disposed in an end portion on a side close to the low temperature heat exchanger, within an end portion of the pulse tube
Implementation Method 2
a low temperature heat exchanger that is disposed in the low temperature end of the regenerator, and that has a gas flow passage for the working gas
Implementation Method 3
a regenerator that has a low temperature end and high temperature end
Implementation Method 4
a Stirling pulse tube refrigerator employs a refrigeration cycle which is based on a reversible process
Data Source
AI summary
A Stirling-type pulse tube refrigerator includes: a regenerator that has a low temperature end and high temperature end; a pulse tube that is arranged coaxially with the regenerator, and that is connected to the regenerator so as to enable working gas to circulate therebetween; a low temperature heat exchanger that is disposed in the low temperature end of the regenerator, and that has a gas flow passage serving as a flow passage for the working gas; and a flow straightener that is disposed in an end portion, on a side close to the low temperature heat exchanger, out of end portions of the pulse tube. The gas flow passage and the flow straightener are spaced away from each other, and a length of a connecting passage connecting the gas flow passage and the flow straightener is equal to or shorter than 10% of a length of the pulse tube.