Rare-earth cold storage material particle, rare-earth cold storage material particles, refrigerator utilizing same, measuring device, and method for producing same
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Solution Overview
Problem
Conventional regenerator materials for cryogenic refrigerators face challenges in achieving high-density filling and maximizing the contact surface area with the operating medium gas, leading to limitations in refrigerating performance and reliability, especially at extremely low temperatures.
Innovation Solution
Rare-earth regenerator material particles with specific size and shape characteristics, such as an average size of 0.01 to 3 mm, a high proportion of particles with an aspect ratio of 2 or less, and depressed portions on the surface, are used to enhance packing density and contact surface area, along with a manufacturing method involving rapid quenching and argon atmosphere processing.
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 is limited
Solution Approach 1:
The invention introduces asymmetric depressed portions on the particle surfaces, creating uneven contact zones that increase the effective surface area for gas interaction while maintaining overall spherical shape for efficient packing. The depressed portions break the symmetry of conventional spherical particles, providing both high-density filling capability and enhanced contact surface area.
Solution Approach 2:
The depressed portions on particle surfaces create micro-porous structures that increase the effective surface area available for gas contact. These surface features act as porous elements that enhance heat and mass transfer between the regenerator material and He gas while maintaining the structural integrity needed for high-density packing.
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 particle surface is segmented into multiple depressed portions, creating localized zones of enhanced surface area without reducing the overall particle size. This segmentation allows the gas to access multiple contact zones on each particle while maintaining adequate inter-particle spacing for gas permeability.
Solution Approach 2:
The depressed portions add a third-dimensional feature to the particle surface, creating micro-cavities and uneven topography that increase effective surface area without reducing particle diameter. This dimensional enhancement allows increased contact area while preserving the particle size needed for gas flow permeability.
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 depressed portions on particle surfaces act as cushioning features that absorb impact stresses during high-pressure filling. These surface indentations provide stress concentration zones that prevent crack propagation and particle fragmentation, allowing high-density packing without particle crushing and subsequent system clogging.
Solution Approach 2:
The surface morphology parameter is changed by introducing depressed portions, which fundamentally alters the mechanical response of particles to compression. This parameter change enables particles to withstand high filling pressures without crushing, as the depressed portions distribute and absorb mechanical stresses that would otherwise cause particle failure.
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
The solution enables high-density filling and increased contact surface area between regenerator material particles and the operating medium gas, significantly improving the refrigerating performance and reliability of cryogenic refrigerators and associated measuring apparatus.
Implementation Method 1
a step of rapidly cooling (quenching) the molten metal having a granular form flipped by the rotary disk
Implementation Method 2
the refrigerating performance of a refrigerator depends on amount of He gas having contact with the surface of the regenerator material particles
Data Source
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.