Cryogenic apparatus
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Solution Overview
Problem
Existing cryogenic apparatuses, such as thermo-mechanical coolers, often require direct contact between the specimen and the cold head, which is not always convenient, and may produce vibrations that need to be inhibited.
Innovation Solution
A cryogenic apparatus with a sample tube and a thermo-mechanical cooler that uses helium gas to achieve low temperatures, featuring a heat exchanger and a thermal element for controlled fluid flow, allowing for dynamic and static cooling modes, and a vibration-suppressing linkage to minimize specimen vibration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a specimen is placed in direct contact with the cold head of a thermo-mechanical cooler, then cooling efficiency is improved, but vibration is increased and convenience is reduced
Solution Approach 1:
The patent introduces a sample tube as an intermediary component between the specimen and the cold head. The sample tube can be evacuated to create a vacuum environment, allowing thermal contact with the cold head while isolating the specimen from mechanical vibrations. This mediator enables thermal coupling without direct mechanical contact, resolving the contradiction between cooling efficiency and vibration reduction.
2Object-affected harmful factors
If a sample tube is introduced to isolate the specimen from the cold head, then vibration is reduced, but thermal contact efficiency decreases
Solution Approach 1:
The sample tube is designed to be evacuable, creating a vacuum or low-pressure environment inside the tube. This pneumatic modification allows for improved thermal contact between the specimen and the tube wall while maintaining vibration isolation. The vacuum environment eliminates convection and reduces heat transfer barriers, compensating for the thermal resistance introduced by the tube wall.
3Stability of the object's composition
If the enclosure is evacuated to suppress heat transfer by convection, then thermal isolation is improved, but heat transfer to the specimen becomes less efficient
Solution Approach 1:
The patent applies different thermal conditions in different locations: the enclosure is evacuated to provide thermal isolation and suppress convection, while the sample tube region maintains direct thermal contact with the cold head through conduction. This local differentiation allows the system to benefit from both thermal isolation in the enclosure and efficient heat transfer at the specimen location, resolving the contradiction between thermal isolation and heat transfer efficiency.
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
Enables efficient cooling of specimens to temperatures below 10 K, with the ability to inhibit vibration, allowing for precise temperature control and rapid cooling in dynamic mode and natural convection in static mode, facilitating various experimental conditions.
Implementation Method 1
Gas expansion takes in heat from the environment at one end of the cylinder, so one end of the cylinder may be referred to as a cold head
Implementation Method 2
a cylinder contains a displacer and regenerator. A mechanical valve connects the cylinder to the gas at low pressure and high pressure alternately
Implementation Method 3
The sample tube can be evacuated, and any air in the sample tube would then be extracted by a pump
Implementation Method 4
a first inlet to allow a fluid into the sample tube in the vicinity of a specimen, and a second inlet to supply fluid to a thermal element in thermal contact with the sample tube
Implementation Method 5
a second inlet to supply fluid to a thermal element in thermal contact with the sample tube in the vicinity of the specimen
Data Source
AI summary
A cryogenic apparatus (10) comprises: an enclosure (12); a thermo-mechanical cooler (22) and a sample tube (20) that both project into the enclosure (12), where the sample tube (20) has a closed end; a pump (92) with a pump inlet and a pump outlet, and a duct to supply helium gas from the pump outlet to the thermo-mechanical cooler (22) to produce cold helium. The sample tube (20) has a first inlet (74) to allow a fluid into the sample tube (20), and a second inlet (83) to supply fluid to a thermal element (42) in thermal contact with the sample tube (20), and also has a first outlet (26) to withdraw fluid from within the sample tube (20), and a second outlet (28) to withdraw fluid from the thermal element (42). The apparatus also comprises a first duct including a first valve (80) to supply the cold helium to the first inlet (74) and a second duct including a second valve (82) to supply the cold helium to the second inlet (83); and either or both of the first outlet (26) and the second outlet (28) may be connected to the inlet of the pump (92). This enables a specimen to be cooled either in a static mode, relying on natural convection, or in a dynamic mode, with a forced gas flow, or using both modes at once. These different options enable an operator to achieve different cooling rates.