Linear Cryocooler Compression Chamber Heat Rejection Path

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Solution Overview

Problem

Conventional linear cryocoolers face inefficiencies due to poor thermal paths from the compression chamber to the heat sink, leading to reduced thermodynamic efficiency and potential catastrophic failures from thermal expansion, especially in high-power applications.

Innovation Solution

A more direct thermal path is achieved by allowing convection of working gas into the housing and using gas ports in the regenerator to facilitate heat rejection directly through the sealed housing, reducing thermal resistance and improving heat transfer efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If conventional thermal paths are used from compression chamber to heat sink, then device complexity is reduced, but heat transfer efficiency deteriorates and thermal resistance increases

Engineering Contradiction:
Improveheat transfer efficiencyVSAvoidthermal path complexity
Core Design Contradiction:
Loss of energyVSDevice complexity

Solution Approach 1:

The patent extracts the thermal management function from the conventional integrated design by providing a dedicated thermal path that is thermally coupled to the compression chamber. This separate thermal path includes thermal conduction members that directly conduct heat from the compression chamber to the heat sink, bypassing the inefficient conventional thermal path and achieving 10X improvement in heat rejection thermal resistance.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The thermal management system is segmented into distinct functional components: the compression chamber, dedicated thermal path, thermal conduction members, and heat sink. This segmentation allows each component to be optimized for its specific function, with the thermal conduction members providing direct heat conduction while the housing provides structural support and sealing.

Inventive Principle:
Principle #1Segmentation

2Reliability

If conventional thermal paths are used, then device structure is simplified, but temperature rise from heat sink to compression chamber increases causing thermal expansion failures

Engineering Contradiction:
Improvethermal expansion failure resistanceVSAvoidtemperature rise
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent extracts the heat rejection function into a separate dedicated thermal path that is thermally coupled to the compression chamber. This thermal path includes thermal conduction members that directly conduct heat to the heat sink, reducing thermal resistance by 10X and preventing thermal expansion failures by maintaining lower temperatures in the compression chamber.

Inventive Principle:
Principle #2Taking out (Extraction)

3Productivity

If direct thermal path is implemented, then heat rejection efficiency is improved, but device complexity increases

Engineering Contradiction:
Improveheat rejection rateVSAvoidthermal path structure
Core Design Contradiction:
ProductivityVSDevice complexity

Solution Approach 1:

The patent merges the thermal management function with the existing housing structure. The housing is thermally coupled to the compression chamber and provides both structural support and thermal conduction pathways. The thermal conduction members are integrated into this housing structure, achieving direct heat rejection without adding significant structural complexity.

Inventive Principle:
Principle #5Merging (Combining)

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 design results in a minimum 10X improvement in heat rejection thermal resistance, increasing Carnot efficiency and enabling higher power applications by reducing the temperature rise from the heat sink to the compression chamber, with expected efficiency improvements of 20% for low power and being enabling for high power applications.

Implementation Method 1

allowing convection of the working gas into the housing

Methodology Applied
Scientific EffectConvection: Convection

Implementation Method 2

using gas ports in the regenerator to facilitate heat rejection directly through the sealed housing

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Data Source

PatentEP2440863B1High efficiency compact linear cryocooler
Publication Date: 2018.11.14 RAYTHEON CO
  • EP2440863B1 patent drawingFigure 1
  • EP2440863B1 patent drawingFigure 2
  • EP2440863B1 patent drawingFigure 3

AI summary

A method of removing heat due to compression of a working gas from a linear cryocooler is disclosed. The cryocooler includes a sealed housing, a displacer including a displacer piston and a displacer cylinder, and a compressor all arranged within the housing. The compressor includes a compressor piston that is movable within a compression chamber. The method includes providing a port in the compression chamber to remove heat from the compression chamber due to the compression of the working gas to the housing prior to entering the displacer piston.