Cryogenic refrigeration device
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Solution Overview
Problem
Existing cryogenic refrigeration devices face limitations in achieving very low temperatures, particularly below 4 K, due to the limitations of pulse tube coolers and 'wet' solutions which require long cooling and reheating times and present sealing challenges, making them unsuitable for applications requiring increased cooling power.
Innovation Solution
The device employs a cryogenic cooler with a cycle fluid thermodynamic cycle and a set of heat exchangers to achieve multiple cold temperatures, using a liquefied cycle fluid like helium or nitrogen, with separate heat exchangers connected mechanically and arranged vertically, allowing for efficient cooling and reheating without direct contact with the enclosure's internal gas volume.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a pulse tube cooler is used to achieve cooling power below 4 K, then the cooling temperature is improved, but the cooling power is insufficient and not suitable for applications requiring increased cooling power
Solution Approach 1:
The device divides the cooling system into multiple independent thermal stages using separate plates (first plate, second plate, third plate) each cooled to different temperatures. Each plate can be independently controlled and optimized for specific temperature requirements, allowing the system to provide both low temperatures and sufficient cooling power simultaneously.
Solution Approach 2:
A cycle fluid (such as helium or nitrogen) is introduced as an intermediary medium to transfer thermal energy between the cryogenic cooler and the plates. The fluid circulates through heat exchangers connected to each plate, enabling efficient heat transfer and allowing the system to deliver adequate cooling power to multiple temperature stages.
2Power
If a wet solution with liquid helium bath is used to cool the plates, then the cooling power is improved, but the sealing becomes complex and access for samples and cables is complicated
Solution Approach 1:
The invention extracts the cycle fluid from the direct contact with samples and cables by using sealed heat exchangers. The fluid circulates in closed loops connected to each plate through thermally conductive connections, providing cooling power without requiring the fluid to be in direct contact with the sample environment, thus simplifying sealing and access.
Solution Approach 2:
The heat exchangers are nested within the vacuum enclosure structure, with each heat exchanger integrated into or near its corresponding plate. This nested arrangement allows the cooling system to be compact while maintaining separate sealed circuits for the cycle fluid, avoiding the need for complex external sealing arrangements.
3Power
If a wet solution with liquid helium bath is used to cool the plates, then the cooling power is improved, but the cooling and reheating times become relatively long
Solution Approach 1:
The system uses dynamic control of the cycle fluid circulation to optimize cooling and reheating speeds. The flow rate and temperature of the cycle fluid can be adjusted independently for each plate, allowing rapid response to temperature changes and reducing the time required for cooling down or reheating compared to static bath solutions.
Solution Approach 2:
The cycle fluid circulation operates continuously through the heat exchangers, maintaining constant thermal contact with each plate. This continuous action enables faster heat transfer during both cooling and reheating phases compared to batch-style bath cooling, as the fluid constantly replenishes its cooling capacity throughout the process.
4Measurement precision
If multiple separate heat exchangers are used to cool multiple plates, then the temperature control precision is improved, but the device complexity increases
Solution Approach 1:
Multiple heat exchangers are merged into a single integrated assembly that can be installed together through one opening in the vacuum enclosure. The heat exchangers share common structural support and are connected through the cycle fluid distribution system, reducing the number of separate installation operations and simplifying the overall device architecture while maintaining independent temperature control for each plate.
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 rapid cooling and reheating, increases cooling power, and reduces the risk of leakage, allowing for efficient cooling of samples to sub-kelvin temperatures, overcoming the limitations of prior art by providing a more flexible and efficient refrigeration system.
Implementation Method 1
a cryogenic cooler of the type which uses a cold source of liquefied cycle fluid such as helium or nitrogen
Implementation Method 2
cryogenic cooler of the He4 or He3 Joule-Thomson type
Implementation Method 3
at least some of the plates being cooled by the cycle fluid via a set of heat exchangers in heat exchange with said plates
Implementation Method 4
at least one of the plates being connected to a thermal shield forming a volume which encloses at least one following plate
Data Source
AI summary
A cryogenic refrigeration device is provided that may include: an enclosure delimiting a vacuum-sealed volume closed by a cover; and at least one cryogenic refrigerator mounted through the cover and having a first end situated outside the enclosure and a second end situated inside the enclosure, the cryogenic refrigerator being configured to supply cold at its second end. The device can also include at least two thermally conductive plates distributed according to a direction of distribution within the enclosure and forming thermal stages, at least some of the plates being cooled by the cryogenic refrigerator to respective determined temperatures decreasing in the direction of distribution, at least one of the plates being connected to a heat screen forming a volume that encompasses at least one following plate, the cryogenic refrigerator being of the type using a cold source of liquefied cycle fluid such as helium or nitrogen, at least some of the plates being cooled by the cycle fluid via a set of heat exchangers that exchange heat with said plates and with a flow of the cycle fluid.