NMR Cryoprobe Cooling Circuit with Counterflow Heat Exchanger
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing NMR apparatuses with superconducting magnet coil systems and cryoprobe heads face high cooling costs and vibration transmission issues due to the need for cryocoolers to operate below the boiling temperature of liquid helium, and they often require frequent refilling of cryogenic liquids, which increases costs and complicates maintenance.
Innovation Solution
A counterflow heat exchanger is integrated into the cryostat vacuum or helium container, allowing the cooling circuit of the NMR cryoprobe head to direct cooling fluid to the second cooling stage of the cryocooler, reducing the inlet temperature and thereby lowering the helium evaporation rate, allowing for a less expensive cooler and reducing vibration transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If the cryocooler operates below the boiling temperature of liquid helium to cool the NMR cryoprobe head, then the cooling performance is improved, but the cooling costs increase and vibrations are transmitted to the cryostat
Solution Approach 1:
The patent merges the cooling functions by integrating the NMR cryoprobe head cooling circuit with the cryostat cooling system. The heat exchanger in the liquid helium bath allows both the superconducting magnet and the NMR probe components to share the same cryogenic cooling resource, eliminating the need for a separate cryocooler operating below helium boiling point.
Solution Approach 2:
The liquid helium cooling system serves multiple functions simultaneously: it cools the superconducting magnet coil system and also cools the NMR cryoprobe head components through the integrated heat exchanger. This multi-functional approach replaces the need for dedicated cooling systems for each component.
2Temperature
If the cryocooler operates below the boiling temperature of liquid helium, then the cooling performance is improved, but vibration transmission to the cryostat increases
Solution Approach 1:
The patent merges the cooling functions by integrating the NMR cryoprobe head cooling circuit with the cryostat cooling system. The heat exchanger in the liquid helium bath allows both the superconducting magnet and the NMR probe components to share the same cryogenic cooling resource, eliminating the need for a separate cryocooler operating below helium boiling point.
Solution Approach 2:
The liquid helium bath acts as an intermediary thermal medium. Instead of directly coupling the cryocooler to the NMR probe components (which would transmit vibrations), the system uses the liquid helium as a thermal mediator to transfer heat away from the probe components, thereby isolating them from vibration sources.
3Stability of the object's composition
If bath cooling with liquid helium is used for the superconducting magnet coil system, then temperature stability is improved, but frequent refilling is required due to evaporation
Solution Approach 1:
The system uses the cooling demand from the NMR cryoprobe head components as a self-service mechanism to actively remove heat from the liquid helium bath. The heat exchanger integrated in the bath allows the probe cooling circuit to circulate and cool the helium, reducing its temperature and thereby reducing evaporation losses without requiring external intervention or refilling.
Solution Approach 2:
The integrated cooling circuit enables continuous operation by maintaining the liquid helium bath at a lower, more stable temperature through the ongoing cooling demand of the NMR probe components. This continuous active cooling prevents the helium from reaching its boiling point and evaporating, ensuring uninterrupted operation.
4Adaptability or versatility
If a separate cooling circuit is used for the NMR cryoprobe head, then cooling independence is improved, but device complexity increases
Solution Approach 1:
The patent merges the cooling functions by integrating the NMR cryoprobe head cooling circuit with the cryostat cooling system. The heat exchanger in the liquid helium bath allows both the superconducting magnet and the NMR probe components to share the same cryogenic cooling resource, eliminating the need for a separate cryocooler operating below helium boiling point.
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 reduces helium evaporation rates, lowers cooling costs, and minimizes vibration transmission to the superconducting magnet assembly, enabling a more efficient and cost-effective cooling system that maintains signal quality without the need for frequent liquid refills.
Implementation Method 1
A counterflow heat exchanger is integrated into the cryostat vacuum or helium container, allowing the cooling circuit of the NMR cryoprobe head to direct cooling fluid to the second cooling stage of the cryocooler
Implementation Method 2
Superconducting magnetic coil systems are operated in a cryostat to keep the temperature below the superconductor transition temperature
Implementation Method 3
the cooling takes place by thermally connecting the superconducting magnet coil system and/or one or more radiation shields of the cryostat to a cooling stage of a cryocooler
Implementation Method 4
Helium gas from the neck tube is passed through a refrigeration circuit into an NMR cryoprobe. At the lower (coldest) end of the neck tube, helium gas is liquefied and flows back into the cryostat's helium vessel
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A superconducting magnet arrangement (27) with cryostat, vacuum chamber (102) and cooling stage, with NMR probe head (11) with cooled probe head components (9, 10), wherein a cryocooler (2) with a second cooling stage (4) at operating temperature < 35.4 K and a first cooling stage (3) above 35.4 K is arranged in a thermally insulated housing (1) together with a counterflow heat exchanger (8) with two inlets and outlets, wherein cooling fluid is directed from a heat exchanger on the first cooling stage to the first inlet of the counterflow heat exchanger, from the second outlet to a heat exchanger on the second cooling stage, to a cooled probe head component and to a heat exchanger (202) in the cryostat vacuum, is characterized in thatthat the cooling fluid is directed either directly from the second outlet of the counterflow heat exchanger or indirectly via a heat exchanger on the second cooling stage and/or via a cooled sample head component to a heat exchanger in the cryostat vacuum or to a heat exchanger (205) in a suspension tube of a helium container and to the second inlet of the counterflow heat exchanger, such that both the inlet temperature of the cooling fluid flowing into the heat exchanger in the cryostat vacuum or in the suspension tube and the return temperature of the cooling fluid flowing out are at least 5 K lower than the operating temperature of the first cooling stage. This allows the excess cooling capacity of the cryocooler to reduce the evaporation rate of liquid helium or to cool a superconducting magnetic coil system in a cryogen-free cryostat.