Cryogenic Thermal Buffer Vessels for Helium Pressure Control
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Solution Overview
Problem
Conduction-cooled superconducting magnets face challenges in maximizing heat capacity while minimizing the risk of air ingress and managing pressure fluctuations, which affects ride-through time and safety during quench events.
Innovation Solution
A thermal buffer system with two or more interconnected vessels, where one vessel is in thermal contact with the cold mass at cryogenic temperatures and another at room temperature, allowing helium to expand and maintain positive pressure without releasing gas to the atmosphere, thus maximizing heat capacity and safety.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a thermal buffer is fully filled with liquid helium at cryogenic temperatures, then heat capacity is maximized, but pressure exceeds safe limits when warmed to room temperature
Solution Approach 1:
The thermal buffer system is divided into two separate vessels: a cryogenic vessel for storing liquid helium at low temperatures and a room-temperature vessel for accommodating the expanded helium gas. This segmentation allows each vessel to be optimized for its specific temperature range and pressure conditions, enabling the system to maintain maximum heat capacity while preventing dangerous pressure buildup during warm-up.
Solution Approach 2:
The system exploits the temperature-dependent parameter changes of helium, particularly its expansion ratio from liquid to gas phase. By designing the room-temperature vessel with sufficient volume to accommodate the maximum expected expansion, the system allows helium to naturally expand as temperature increases without generating excessive pressure, thus maintaining safety while preserving full heat capacity.
2Quantity of substance
If a thermal buffer is sealed to retain all helium gas during warm-up, then heat capacity is maximized, but material strength requirements become excessively high
Solution Approach 1:
The buffer system is segmented into two vessels connected by a conduit, allowing the helium to be retained in the system while distributing the pressure load. The cryogenic vessel maintains liquid helium for heat capacity, while the room-temperature vessel accommodates gas expansion at lower pressure, eliminating the need for a single ultra-strong vessel.
Solution Approach 2:
The solution adds a spatial dimension to the buffer system by using multiple vessels at different locations and temperatures. This dimensional approach allows the system to manage pressure and heat capacity separately in different spatial zones, avoiding the need for excessive material strength in any single component.
3Strength
If the buffer system operates at atmospheric pressure, then material strength requirements are reduced, but air ingress becomes a risk
Solution Approach 1:
The system applies different pressure conditions to different parts of the buffer system. The cryogenic vessel operates at slightly positive pressure to prevent air ingress, while the room-temperature vessel operates at atmospheric pressure to minimize material strength requirements. This localized quality approach allows each vessel to be optimized for its specific operational requirements.
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
The system enables a fully filled thermal buffer to operate with reduced material strength requirements, maintaining positive pressure and preventing air ingress, thereby extending ride-through time and reducing operational costs and safety hazards.
Implementation Method 1
When the cryogenic buffer vessel of the system is warmed, the helium liquid within the cryogenic vessel is converted to helium gas which expands and pressurizes both the cryogenic and room temperature buffer vessels
Implementation Method 2
the helium liquid within the cryogenic vessel is converted to helium gas which expands and pressurizes both the cryogenic and room temperature buffer vessels
Implementation Method 3
The system enables a fully filled thermal buffer to operate with reduced material strength requirements, maintaining positive pressure and preventing air ingress, thereby extending ride-through time
Implementation Method 4
one vessel is in thermal contact with the cold mass at cryogenic temperatures
Data Source
AI summary
Apparatus and methods to add heat capacity to a cryogenic apparatus such as a superconducting magnet are provided. A body of liquid cryogen having a relatively high heat capacity is stored at cryogenic temperatures in a low temperature vessel that is thermally linked to a cold mass within the cryogenic apparatus. The low temperature vessel is connected to a manifold system located on the exterior of the cryogenic apparatus. The manifold is further connected to a room temperature vessel so that gas is allowed to freely move between the low temperature and room temperature vessels. In one exemplary mode of operation, it is possible to simultaneously operate the system with a full capacity of liquid cryogen in the low temperature vessel, operate the system with a maximum pressure substantially below 757 atmospheres regardless of the temperature of the low temperature vessel, operate the system with positive pressure regardless of the temperature of the low temperature vessel, and cycle the temperature of the low temperature vessel between room and cryogenic temperatures without releasing gas from the system.