Serial Circulating Loop Cryocooler for Remote Load Refrigeration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Regenerative-cycle cryogenic refrigerators, such as Gifford-McMahon (GM) or pulse tube cryocoolers, are limited in providing refrigeration only at the cold surface of the cold head, with low-pressure gas returned at room temperature, making it difficult to cool loads remote from the cold head effectively.
Innovation Solution
A circulating loop is connected serially between the GM or GM type Pulse Tube cold head and the compressor, diverting a fraction or all of the gas to be cooled by the cold head for refrigeration at a remote load, using a counter-flow heat exchanger and a circulation control valve to optimize cooling, allowing gas to flow through a heat exchanger between the cold head and compressor at ambient temperature.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a regenerative-cycle cryogenic refrigerator (GM or pulse tube) is used, then refrigeration efficiency and compact size are improved, but the refrigeration is only available at the cold surface of the cold head and cannot cool remote loads
Solution Approach 1:
The patent introduces a circulating fluid (gas or liquid) as an intermediary carrier to transport refrigeration from the cold head to remote loads. The fluid absorbs heat at the cold head and releases it at remote locations through heat exchangers, enabling thermal energy transport without direct mechanical connection. This resolves the contradiction by maintaining the efficiency of regenerative-cycle cryocoolers while extending their cooling capability to remote positions.
Solution Approach 2:
The patent employs fluid circulation systems (pneumatic for gas, hydraulic for liquid) to transport refrigeration. The circulating fluid acts as a mobile heat exchanger, absorbing thermal energy at the cold head and delivering it to remote loads. This approach enables remote cooling while preserving the compact and efficient characteristics of the original cryocooler system.
2Adaptability or versatility
If a circulating loop with cold circulator is used to transport refrigeration, then remote cooling capability is improved, but the entire circulating loop must be maintained at cold temperature increasing system complexity
Solution Approach 1:
The patent applies local quality by maintaining cold temperature only where needed (at the cold head and immediate vicinity) while allowing the majority of the circulating loop to operate at ambient or higher temperatures. Heat exchangers are strategically positioned to transfer thermal energy locally, eliminating the need to cool the entire circulation system. This reduces thermal management complexity while preserving remote cooling capability.
Solution Approach 2:
The circulating fluid serves as a thermal intermediary that temporarily stores and transports refrigeration energy. The fluid absorbs heat at the cold head, carries it through the circulation loop, and releases it at remote heat exchangers. This mediator approach allows the bulk of the system to remain at higher temperatures while achieving effective remote cooling.
3Device complexity
If a circulating loop with warm circulator is used to transport refrigeration, then device complexity is reduced, but the cold head and remote load must be at significantly lower temperatures requiring efficient heat exchangers
Solution Approach 1:
The patent utilizes parameter changes in the circulating fluid's thermal properties to optimize heat transfer. By controlling the fluid's temperature, pressure, and flow rate parameters, the system achieves efficient heat exchange between the warm circulator and cold components. The fluid undergoes cyclic parameter changes as it absorbs and releases thermal energy, enabling effective heat transfer across temperature gradients without requiring the entire system to be cold.
Solution Approach 2:
The circulating fluid acts as a thermal mediator between the warm circulator system and cold components. It absorbs heat from the cold head and delivers it to remote loads, bridging the temperature gap without requiring the circulator mechanism itself to be cold. This intermediary approach reduces device complexity while managing the temperature differential through efficient heat exchanger design.
4Ease of manufacture
If separate circulating loop and cryocooler systems are used, then system modularity is improved, but fluid sharing and exchange between systems is not achieved reducing cooling efficiency
Solution Approach 1:
The patent merges the circulating loop and cryocooler systems by allowing them to share and exchange the same circulating fluid. The fluid circulation path integrates both the cold head operation and remote load cooling functions, eliminating the need for separate fluid systems. This combination maintains modularity benefits while improving cooling efficiency through unified fluid management and reduced thermal losses.
Solution Approach 2:
The circulating fluid serves multiple functions simultaneously: it cools the cold head, transports refrigeration to remote loads, and can be optimized for different operating conditions. The single fluid system performs both the cryocooler's internal cooling cycle and the external remote cooling function, achieving multi-functionality that improves overall system efficiency while maintaining modular architecture.
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 configuration enables efficient refrigeration transport to remote loads by actively controlling the circulation loop, minimizing temperature differences and optimizing cooling rates, achieving effective cryogenic refrigeration across a broad temperature range.
Implementation Method 1
Circulating gas flows through a counter-flow heat exchanger located between the lines connected to the cold head and compressor
Implementation Method 2
at least one Gifford-McMahon (GM) or GM type pulse tube cold head receiving gas at ambient temperature from said compressor in a line at high pressure and returning the gas in a line at low pressure, producing refrigeration at one or more cold surfaces of the GM or GM type pulse tube
Data Source
AI summary
A circulating loop for transporting refrigeration to a remote location is connected serially between a Gifford-McMahon (GM) or GM type Pulse Tube cold head and the compressor. Either high pressure gas from the compressor can flow through the remote heat station before returning to the cold head or low pressure gas can flow from the cold head to the remote heat station before returning to the compressor. A first fraction of gas, which may include all of the gas at ambient temperature, enters a counter-flow heat exchanger, is cooled by the cold head, flows to the remote load, and then returns to ambient temperature as it flows through the counter-flow heat exchanger. The high or low pressure line may have a circulation control valve that diverts a second fraction of gas to flow directly between the cold head and compressor. A controller adjusts the circulation control valve to optimize the cooling of the load.