Silver Oxide Regenerator Material for High Specific Heat Cryocooling

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Solution Overview

Problem

Current regenerative cryocoolers using materials like Bi and Sn compounds have insufficient specific heat at low temperatures, leading to inferior cooling properties compared to Pb-based systems, and require materials with high thermal conductivity and mechanical strength for efficient heat transfer and diffusion.

Innovation Solution

A cryogenic regenerator material comprising silver oxide with a molar ratio of silver to oxygen atoms between 1.0 and 4.0, preferably 1.8 to 3.2, which provides high specific heat, thermal conductivity, and mechanical strength, optimized through specific composition and crystal structure combinations of silver oxides like Ag2O and Ag3O, and a sintered bulk body form for enhanced performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If Pb is used as regenerator material, then cooling properties are improved, but environmental burden increases

Engineering Contradiction:
Improvecooling propertiesVSAvoidenvironmental burden
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The invention changes the material composition parameters by using silver oxide with controlled oxygen content (molar ratio of Ag to O atoms between 1.0 and 4.0) to achieve the desired specific heat capacity while eliminating toxic Pb. This parameter optimization allows the material to match or exceed Pb's thermal performance without environmental harm.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention employs composite material design by combining silver oxide with specific crystal structures and controlling oxygen stoichiometry to create a material that integrates multiple desirable properties: high specific heat, high thermal conductivity, and high mechanical strength, while being environmentally benign.

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If Bi, Sn or their compounds are used as substitutes for Pb, then environmental burden is reduced, but specific heat at low temperatures becomes insufficient

Engineering Contradiction:
Improveenvironmental burdenVSAvoidspecific heat
Core Design Contradiction:
Object-affected harmful factorsVSQuantity of substance

Solution Approach 1:

The invention optimizes the oxygen content parameter in silver oxide (molar ratio of Ag to O atoms between 1.0 and 4.0) to precisely control the specific heat capacity. By adjusting this compositional parameter, the material achieves high specific heat at low temperatures while maintaining environmental friendliness.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The invention applies local quality optimization by controlling the oxygen distribution and crystal structure at the atomic level within the silver oxide lattice. This local structural control enables enhanced specific heat capacity in the cryogenic temperature range while maintaining overall material stability and environmental compatibility.

Inventive Principle:
Principle #3Local quality

3Use of energy by moving object

If regenerator material has high thermal conductivity, then heat transfer efficiency is improved, but mechanical strength may be compromised

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidmechanical strength
Core Design Contradiction:
Use of energy by moving objectVSStrength

Solution Approach 1:

The invention uses composite material design with silver oxide in specific crystal structures that inherently provide both high thermal conductivity and high mechanical strength. The controlled oxygen stoichiometry creates a robust lattice structure that simultaneously enables efficient heat diffusion and resists mechanical degradation during reciprocating motion.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention optimizes local atomic arrangement and crystal structure in the silver oxide material to create regions with enhanced thermal conductivity while maintaining overall structural integrity. The controlled oxygen content creates a lattice configuration that facilitates phonon transport while preserving mechanical strength.

Inventive Principle:
Principle #3Local quality

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 silver oxide regenerator material achieves superior specific heat and thermal conductivity, supporting improved refrigeration performance and mechanical stability, while being environmentally friendly and suitable for cryogenic temperature ranges.

Implementation Method 1

rapid heat transfer from gas to the regenerator material is desired. Thus, efficient heat transfer between the gas and regenerator material, and heat diffusion in the regenerator material are important

Methodology Applied
Scientific EffectHeat transfer: Conduction (thermal)

Implementation Method 2

appropriate regenerator materials are used in consideration of their temperature dependences of specific heat

Methodology Applied
Scientific EffectSpecific heat: Heat Treatment

Implementation Method 3

the regenerator material is required to have high thermal conductivity. Further, in the case of Gifford-McMahon cryocoolers and Stirling cryocoolers, regenerators themselves filled with regenerator materials also move reciprocally

Methodology Applied
Scientific EffectThermal conductivity: Conduction (thermal)

Data Source

PatentEP3284798B1Regenerative cryocooler and system including regenerative cryocooler
Publication Date: 2019.07.03 KK TOSHIBA
  • EP3284798B1 patent drawingFigure 1A~1C
  • EP3284798B1 patent drawingFigure 2A~2B
  • EP3284798B1 patent drawingFigure 3

AI summary

According to a variation, a cryogenic regenerator material contains a silver oxide. A molar ratio of silver atoms to oxygen atoms contained in the cryogenic regenerator material: Ag/O is 1.0 or more and 4.0 or less. The cryogenic regenerator material contains at least one selected from AgO, Ag2O and Ag3O as the silver oxide.