Method for cooling a superconducting cable

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing cooling systems for high-temperature superconducting cables face challenges with high maintenance and operating costs, large space requirements, and inefficient heat exchangers due to the limitations of Stirling cryocoolers and conventional Brayton processes.

Innovation Solution

Implementing a cooling method using a Brayton cryocooler with a subcooling process that includes a counterflow heat exchanger or liquid bath, and utilizing a compact main heat exchanger by withdrawing a portion of the liquid nitrogen to heat and expand it within the Brayton process, enhancing thermal efficiency and reducing the size of the heat exchanger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of stationary object

If a conventional Brayton process or Stirling cryocooler is used for cooling superconducting cables, then cooling capacity can be achieved, but the main heat exchanger volume is large and maintenance costs are high

Engineering Contradiction:

Improvemain heat exchanger volumeVSAvoidmaintenance costs

Core Design Contradiction:

Volume of stationary objectVSReliability

Solution Approach 1:

The patent applies parameter changes by subcooling the liquid nitrogen below its standard boiling point temperature. This temperature parameter change allows the liquid nitrogen to absorb more heat during evaporation, increasing the temperature difference in the heat exchanger and thereby reducing the required heat exchanger volume while maintaining cooling capacity

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent implements preliminary action by subcooling the liquid nitrogen before it enters the heat exchanger. This pre-cooling step prepares the liquid nitrogen to undergo more effective heat absorption during the subsequent evaporation process, improving overall system efficiency and reducing equipment size

Inventive Principle:

Principle #10Preliminary action

2Loss of energy

If liquid nitrogen is subcooled to increase temperature difference in the heat exchanger, then thermal efficiency improves, but the risk of liquid nitrogen solidification increases

Engineering Contradiction:

Improvethermal efficiencyVSAvoidsolidification risk

Core Design Contradiction:

Loss of energyVSObject-affected harmful factors

Solution Approach 1:

The patent employs feedback control by continuously monitoring the temperature of the subcooled liquid nitrogen and adjusting the subcooling degree accordingly. This ensures the temperature remains above the solidification point while maximizing the temperature difference for efficient heat exchange, thus preventing solidification while maintaining thermal efficiency

Inventive Principle:

Principle #23Feedback

Solution Approach 2:

The patent applies beforehand cushioning by maintaining a safety margin in the subcooling temperature. The liquid nitrogen is subcooled only to a程度 that provides sufficient temperature difference for efficient heat exchange while staying well above the solidification temperature, cushioning against the risk of solidification

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Productivity

If a larger heat exchanger is used to maintain cooling capacity, then cooling performance is ensured, but the space requirement increases

Engineering Contradiction:

Improvecooling capacityVSAvoidheat exchanger volume

Core Design Contradiction:

ProductivityVSVolume of stationary object

Solution Approach 1:

The patent changes the temperature parameter of the liquid nitrogen by subcooling it before heat exchange. This parameter change increases the temperature difference during evaporation, allowing a smaller heat exchanger volume to achieve the same cooling capacity, thus resolving the contradiction between cooling performance and space requirement

Inventive Principle:

Principle #35Parameter changes

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 approach reduces the volume of the main heat exchanger by 75% while maintaining cooling capacity, lowers maintenance and operating costs, and improves thermal efficiency by increasing the temperature difference in the heat exchanger.

Implementation Method 1

After a thermal contact with the superconducting cable to be cooled, by which the liquid nitrogen is heated

Methodology Applied

Scientific EffectThermal contact heat transfer: Conduction (thermal)

Implementation Method 2

at least in part using a refrigerant in a Brayton process in which at least part of the refrigerant is cooled and heated in a heat exchanger

Methodology Applied

Scientific EffectBrayton cycle: Brayton Cycle

Implementation Method 3

said part of the coolant is expanded in order to generate cold which can be used to operate the heat exchanger

Methodology Applied

Scientific EffectEvaporation: Evaporation

Data Source

PatentEP3943833B1Method for cooling a superconducting cable

Publication Date: 2025.09.03 LINDE AG

Figure 1~2
Figure 3~4
Figure 5~6

AI summary

The invention relates to a method for cooling a superconducting cable (1) using a coolant containing or consisting of liquid nitrogen, wherein at least a part of the coolant is subjected to a subcooling step and thereafter brought into thermal contact with the superconducting cable (1) in a cooling cycle, wherein said subcooling step is at least in part performed using a refrigerant provided in a Brayton process in which at least a part of the refrigerant is cooled and heated in a main heat exchanger (11). According to the present invention, a part of the coolant is withdrawn from the cooling cycle and heated in the same main heat exchanger (11) in which at least a part of the refrigerant is cooled and heated in the Brayton process. A corresponding device and a corresponding system are also part of the present invention.