Helium Supply Control for Multi-Refrigerator Cryogenic Cooling
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Solution Overview
Problem
Cryopumps and cryogenic refrigerators face inefficiencies due to inconsistent helium supply, leading to prolonged downtime and economic losses in manufacturing processes, as existing systems struggle to precisely regulate refrigerant flow based on varying demand and temperature requirements.
Innovation Solution
A system comprising a compressor with a high pressure supply line and low pressure return line, coupled with an electronic controller that aggregates demand from multiple refrigerators and adjusts compressor speed using a refrigerant correction metric, ensuring optimal helium supply and reducing waste or inadequacy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a greater supply of helium refrigerant is provided to the cryogenic refrigerator, then the cooling rate increases and cryopumping temperatures are achieved faster, but helium consumption increases and waste occurs when demand is low
Solution Approach 1:
The system dynamically adjusts the compressor speed based on real-time helium demand signals from multiple refrigerators. The electronic controller receives demand information from each refrigerator and modulates the compressor operating speed accordingly, transitioning from static fixed-speed operation to dynamic variable-speed control that matches supply with actual demand.
Solution Approach 2:
The system implements a feedback control mechanism where each refrigerator communicates its helium demand to an electronic controller, which then adjusts the compressor speed to match aggregate demand. This closed-loop feedback system ensures that helium supply is continuously optimized based on actual consumption needs, preventing both excess and insufficient supply.
2Reliability
If the compressor speed is increased to meet peak helium demand, then refrigeration capacity is sufficient, but helium is wasted during low-demand periods
Solution Approach 1:
The compressor operates at variable speeds rather than fixed speed, allowing the system to scale refrigeration capacity dynamically. The electronic controller adjusts compressor speed in real-time based on aggregate helium demand from all refrigerators, ensuring adequate capacity during peak demand while minimizing consumption during low-demand periods.
Solution Approach 2:
The system changes the operating parameters of the compressor by adjusting its speed based on demand conditions. The electronic controller modifies the compressor speed parameter in response to varying helium demand signals, optimizing the balance between refrigeration capacity and helium consumption efficiency.
3Device complexity
If multiple refrigerators share a common helium supply, then system complexity is reduced, but precise regulation of refrigerant flow to each refrigerator becomes difficult
Solution Approach 1:
The electronic controller serves multiple functions: it receives demand signals from multiple refrigerators, aggregates their helium requirements, and controls the compressor speed to satisfy total demand. This multi-functional approach maintains system simplicity while achieving precise flow regulation through centralized intelligent control rather than individual mechanical regulators.
Solution Approach 2:
The system replaces mechanical flow regulation mechanisms with electronic control. Instead of using mechanical valves or flow control devices at each refrigerator, the system uses electronic sensing and control to regulate helium flow by adjusting compressor speed, achieving precise regulation through electronic means rather than mechanical components.
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 solution enables precise control of refrigerant supply, minimizing downtime and economic losses by matching helium delivery to actual demand, optimizing cooling efficiency, and reducing helium consumption.
Implementation Method 1
A compressor is configured to supply a refrigerant through a high pressure supply line
Implementation Method 2
Expansion of refrigerant gas, such as helium, in the refrigerator creates cooling and heat is drawn off the cryogenic array, generating the cryogenic temperatures required to condense gases on the cryogenic array
Implementation Method 3
Cryopumps remove molecules from a vacuum process chamber by cooling a surface to temperatures approaching absolute zero. At such temperatures, gases condense or are adsorbed on the cooled surface, called a cryogenic array, thereby removing molecules from the vacuum process chamber
Implementation Method 4
Inside the refrigerator a displacer, driven by a displacer drive which reciprocates the displacer, regulates the quantity of helium used
Data Source
AI summary
A refrigerant management system controls the supply of refrigerant from two or more variable speed and fixed speed compressors to a plurality of cryogenic refrigerators. The system employs a plurality of sensors to monitor and regulate the overall refrigerant supply to deliver an appropriate refrigerant supply to each of the cryogenic refrigerators. The amount of refrigerant to supply is based on an aggregate demand for refrigerant from the plurality of cryogenic refrigerators and a refrigerant correction metric. An appropriate supply of refrigerant is distributed to each cryogenic refrigerator by adjusting the speed of the variable speed compressors or, alternatively, selectively turning the compressors on or off. The speed of the variable speed compressors is adjusted by determining an amount of refrigerant to supply to the plurality of cryogenic refrigerators. If the aggregate demand for refrigerant exceeds the capacity of the compressors, then the speed of a refrigerator within the plurality of refrigerators is adjusted.