Cryogenic Helium Circulation Using Adsorption Pumps
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Solution Overview
Problem
Conventional cryogenic refrigeration systems, such as dilution refrigerators and pulse tube cryo-coolers, are complex, expensive, and require extensive maintenance, with external gas handling systems prone to leaks and contamination, limiting their reliability and applicability in compact facilities.
Innovation Solution
A cryogenic cycle pulse tube dilution refrigerator (CCCPTDR) system that uses a pulse tube cryo-cooler to provide a cryogenic environment and adsorption pumps to circulate helium without warming it above cryogenic temperatures, eliminating the need for an external gas handling system and reducing system complexity and maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If conventional dilution refrigerators use external gas handling systems with mechanical pumps and compressors to circulate helium, then the system can achieve cryogenic temperatures, but the system becomes large, complex, expensive, and requires extensive maintenance
Solution Approach 1:
The patent extracts and eliminates the external gas handling system, mechanical pumps, and compressors from the refrigeration system. By using an integrated pulse tube cryo-cooler with adsorption pumps contained within the refrigerator itself, the system removes the complex external infrastructure while maintaining cryogenic cooling capability
Solution Approach 2:
The patent merges the cooling function and gas circulation function into a single integrated system. The pulse tube cryo-cooler and adsorption pumps are contained within the refrigerator, combining previously separate external systems into one unified apparatus that reduces complexity and space requirements
2Temperature
If conventional dilution refrigerators use mechanical pumps and compressors for helium circulation, then cooling function is achieved, but reliability decreases due to leaks, contamination, and maintenance requirements
Solution Approach 1:
The patent replaces mechanical pumps and compressors with adsorption-based pumping mechanisms. Adsorption pumps use adsorbent materials to capture and release helium gas through pressure changes, eliminating mechanical moving parts that are prone to failure, leaks, and contamination
Solution Approach 2:
The adsorption pumps are self-contained within the refrigerator system, using the cold environment itself to drive the adsorption and desorption cycles. The system serves itself by utilizing the existing cryogenic conditions to power the gas circulation without requiring external mechanical intervention
3Quantity of substance
If conventional dilution refrigerators use large external gas handling systems, then helium circulation is achieved, but the system size increases making it unsuitable for compact facilities
Solution Approach 1:
The patent nests the adsorption pumps and gas handling components within the internal structure of the pulse tube cryo-cooler and refrigerator chambers. The gas circulation system is embedded within the cooling structure, with adsorption pumps located in the still and condensation chambers, creating a compact nested configuration that maximizes space utilization
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 CCCPTDR system is more compact, reliable, and cost-effective, enabling continuous operation and reducing maintenance demands, making it suitable for applications in limited facilities, such as superconducting computer systems.
Implementation Method 1
Pulse tube cryo-coolers ('PTs') are devices that may replace the liquid helium evaporating bath in CDRs to provide the initial cooling of ̃4K. A typical PT provides cooling power by closed-cycle compression and expansion of helium.
Implementation Method 2
The adsorption pumping technique takes advantage of the tendency of gas to condense or adsorb on cold surfaces and be released again in liquid form under the influence of gravity
Implementation Method 3
a mixture of 3He and 4He separates into two distinct phases and pure 3He can move into a mixture of 3He and 4He in a process analogous to evaporation, providing cooling
Implementation Method 4
the apparatus is typically immersed in an evaporating bath of liquid helium-4 ('4He') to provide the ̃4K background
Data Source
AI summary
Cryogenic refrigeration employs a pulse tube cryo-cooler and a dilution refrigerator to provide very low temperature cooling, for example, to cool superconducting processors. Continuous cryogenic cycle refrigeration may be achieved using multiple adsorption pumps. Various improvements may include multiple distinct thermal-linking points, evaporation pots with cooling structures, and/or one or more gas-gap heat switches which may be integral to an adsorption pump. A reservoir volume may provide pressure relief when the system is warmed above cryo genic temperature, reducing the mass of the system. Additional heat exchangers and/or separate paths for condensation and evaporation may be provided. Multi-channel connectors may be used, and/or connectors formed of a regenerative material with a high specific heat capacity at cryogenic temperature. Flexible PCBs may provide thermal links to components that embody temperature gradients. Various components may be pre-cooled, for example via a switchable thermalization system.