Refrigerator and method for manufacturing the same
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Solution Overview
Problem
Conventional refrigerators face challenges in achieving high-density filling and maximizing the contact surface area with the operating medium gas, such as helium, which affects their refrigerating performance and reliability, especially at extremely low temperatures.
Innovation Solution
The use of rare-earth regenerator material particles with specific size and shape characteristics, including an average particle size of 0.01 to 3 mm and a high proportion of particles with an aspect ratio of 2 or less, along with depressed portions on the surface, to enhance packing density and contact surface area with helium gas.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If spherical regenerator material particles are used to achieve high-density filling, then packing density is improved, but contact surface area with He gas decreases
Solution Approach 1:
The invention employs non-spherical particles with aspect ratios of 0.5 or less (highly elongated or flattened shapes) instead of conventional spherical particles. This asymmetric shape allows particles to pack densely while simultaneously providing larger surface area for gas contact, resolving the contradiction between packing density and contact surface area
Solution Approach 2:
The invention changes the geometric parameters of the regenerator material particles, specifically controlling the aspect ratio to 0.5 or less and setting particle sizes between 0.01-3mm. This parameter optimization enables both high-density filling and increased contact surface area with the working gas
2Area of stationary object
If smaller particles are used to increase contact surface area, then surface area is improved, but permeability of He gas decreases
Solution Approach 1:
The invention optimizes particle size parameters within the range of 0.01-3mm and controls aspect ratio at 0.5 or less, finding the optimal balance where sufficient surface area is achieved without excessively reducing gas permeability
Solution Approach 2:
The invention creates different local structures within the particle assembly - the elongated/flattened particle shapes create channels and void spaces that maintain gas permeability while the increased particle surface area provides enhanced contact area for heat exchange
3Volume of stationary object
If particles are filled under high pressure to increase density, then packing density is improved, but particle crushing occurs causing clogging
Solution Approach 1:
The invention uses particles with controlled curvature characteristics (aspect ratio 0.5 or less) that have enhanced mechanical strength and resistance to crushing under pressure, preventing particle breakdown and subsequent system clogging while still achieving high-density packing
Solution Approach 2:
The invention selects specific particle size and shape parameters (0.01-3mm size range with aspect ratio ≤0.5) that provide optimal mechanical strength to withstand filling pressures without crushing, ensuring long-term system reliability
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 approach enables improved refrigerating performance and reliability by ensuring high-density filling and increased contact surface area, leading to enhanced cooling efficiency and reduced permeability resistance, suitable for applications in superconducting technologies and MRI apparatuses.
Implementation Method 1
the He gas compressed by the compressor is expanded to be cooled by about 60 cycles per minute
Implementation Method 2
a regenerator unit (cold accumulating unit) for keeping the He gas cooled in the expansion unit in the cooled state
Data Source
Figure 1A~2
Figure 3
Figure 4
AI summary
Provided is a group of rare-earth regenerator material particles having an average particle size of 0.01 to 3 mm, wherein the proportion of particles having a ratio of a long diameter to a short diameter of 2 or less is 90% or more by number, and the proportion of particles having a depressed portion having a length of 1/10 to 1/2 of a circumferential length on a particle surface is 30% or more by number. By forming the depressed portion on the surface of the regenerator material particles, it is possible to increase permeability of an operating medium gas and a contact surface area with the operating medium gas.