Pulse-tube refrigerator
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Solution Overview
Problem
Pulse tube refrigerators face issues such as non-uniform flow and temperature distribution in the regenerator, excessive heat exchange temperature differences in the low-temperature end heat exchanger, difficulty in fixing flow-straightening meshes within the pulse tube, and limited ability to directly measure internal temperature and pressure, which hinder performance improvement, especially in high cooling capacity Stirling-type pulse tube refrigerators.
Innovation Solution
The introduction of a draft tube within the regenerator, extending into the low-temperature and high-temperature end heat exchangers and pulse tube, along with a flow-straightening mesh and sensors on the draft tube, helps to create a more uniform flow field, optimize gas flow distribution, and enable precise temperature and pressure measurements without affecting the flow field.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the regenerator and pulse tube diameters are increased to improve refrigeration capacity, then cooling capacity is improved, but bias-flow occurs in the refrigerant inside the regenerator and pulse tube
Solution Approach 1:
The regenerator is segmented by dividing its cross-sectional flow path into multiple channels using flow straightening meshes and draft tubes. This segmentation prevents large-scale radial bias-flow while maintaining high refrigeration capacity through increased surface area for heat exchange.
Solution Approach 2:
Draft tubes are introduced as intermediary structures within the regenerator to guide and straighten the refrigerant flow. These draft tubes act as mediators that redirect the flow path, preventing direct radial bias-flow while maintaining efficient heat transfer between the refrigerant and regenerator matrix.
2Stability of the object's composition
If flow-straightening meshes are installed in the pulse tube to prevent bias-flow, then flow uniformity is improved, but installation becomes difficult
Solution Approach 1:
Instead of installing flow straightening meshes radially within the pulse tube (difficult installation), the solution moves to the axial dimension by placing draft tubes along the pulse tube axis. This dimensional change allows for easier installation while achieving the same flow straightening effect.
Solution Approach 2:
Draft tubes serve as intermediary structures that are easier to install than radial meshes. They can be inserted axially into the pulse tube and provide effective flow guidance without requiring complex radial installation procedures.
3Measurement precision
If sensors are installed to measure internal temperature and pressure, then measurement capability is improved, but the flow field is affected
Solution Approach 1:
Thin-walled draft tubes are used as sensor housings that minimize interference with the flow field. The thin walls reduce flow disturbance while still allowing for accurate temperature and pressure measurements through integrated sensors.
Solution Approach 2:
The draft tubes serve dual functions: they straighten the flow field and simultaneously serve as protective housings for measurement sensors. This self-service approach allows measurement capability without additional flow-disturbing components.
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 reduces bias-flow, enhances heat exchange capacity, facilitates easier installation of flow-straightening meshes, and allows for accurate internal parameter measurement, leading to improved refrigeration performance and efficiency.
Implementation Method 1
a draft tube is provided inside a regenerator, and thus, an air flow exchanging path in a lateral section is blocked and decreased, a flow field becomes more uniform
Implementation Method 2
an axially oriented regenerator, a low-temperature end heat exchanger, a pulse tube, a high-temperature end heat exchanger
Data Source
AI summary
A refrigerator includes a regenerator, a low-temperature end heat exchanger, a pulse tube, a high-temperature end heat exchanger, and a phase adjustment mechanism, connected in that order. A draft tube is provided inside the regenerator, paralleling the regenerator's axis, and the draft tube can extend into the low-temperature end heat exchanger.