Systems and methods for electrostatic trapping of contaminants in cryogenic refrigeration systems
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Solution Overview
Problem
Current dilution refrigeration systems face frequent plugging issues due to contaminants like nitrogen, oxygen, and argon, which solidify and create blockages in the helium circuit, leading to reliability problems and requiring lengthy warm-up and cool-down cycles for maintenance, while existing filters and cold traps are insufficient in removing these contaminants effectively.
Innovation Solution
An electrostatic cryogenic cold trap is employed, which uses a combination of temperature gradients and electric fields to ionize and trap contaminants on surfaces within the trap, enhancing contaminant removal efficiency by maintaining surfaces at specific temperatures and applying different potentials to discharge and collection electrodes, thereby improving the trapping of contaminants like nitrogen, oxygen, and argon.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional filters and cold traps are used to remove contaminants, then contaminant removal is partially achieved, but the removal effectiveness is insufficient and plugging events still occur frequently
Solution Approach 1:
The patent applies parameter changes by transitioning from passive thermal trapping to active electrostatic trapping. The cold trap surfaces are charged to create electric fields that enhance contaminant attraction and capture. This changes the fundamental mechanism from relying solely on temperature-dependent condensation to utilizing electrostatic forces, thereby significantly improving contaminant removal efficiency and preventing plugging events that compromise system availability
Solution Approach 2:
The patent replaces the conventional mechanical/thermal trapping mechanism with an electrostatic field-based mechanism. Instead of relying only on thermal conduction and phase change, the system uses charged surfaces and electric fields to actively attract and trap contaminant ions and molecules. This substitution of the trapping mechanism dramatically enhances the effectiveness of contaminant removal while maintaining system reliability
2Ease of operation
If mechanical pumps and compressors are used to circulate 3He, then refrigeration system operation is maintained, but contaminants are introduced into the helium circuit causing plugging
Solution Approach 1:
The patent converts the harmful effect of mechanical pumping (contaminant introduction) into a beneficial outcome by using the electrostatic cold trap to actively capture and remove these contaminants. The system acknowledges that mechanical pumps will continue to introduce contaminants but compensates by implementing an enhanced electrostatic trapping mechanism that prevents plugging, thus maintaining ease of operation while eliminating the harmful effects
3Reliability
If plugging events occur and warm-up/cool-down cycles are performed for maintenance, then system reliability is restored, but significant operational time is lost
Solution Approach 1:
The patent applies preliminary action by continuously and proactively removing contaminants from the helium circuit before they can accumulate to plugging levels. The electrostatic cold trap operates continuously to trap contaminant ions and molecules, preventing the formation of blockages. This preliminary contaminant removal eliminates the need for periodic warm-up and cool-down maintenance cycles, thereby restoring system functionality without time loss
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 electrostatic cryogenic cold trap significantly reduces the frequency of plugging events by effectively removing contaminants, allowing for continuous operation of dilution refrigeration systems and minimizing the need for frequent maintenance, thereby enhancing the reliability and availability of cryogenic refrigeration systems.
Implementation Method 1
uses a combination of temperature gradients and electric fields to ionize and trap contaminants on surfaces within the trap
Implementation Method 2
An electrostatic cryogenic cold trap is employed, which uses a combination of temperature gradients and electric fields to ionize and trap contaminants on surfaces within the trap
Implementation Method 3
Cryogenic cold traps preferentially remove contaminants from cryogenic refrigeration systems. Such cryogenic cold traps typically operate at temperatures, a range of temperatures, or a temperature gradient at which contaminants such as nitrogen, oxygen, carbon dioxide, argon that may be present in the cryogenic refrigerant are cryocondensed or cryoadsorbed on surfaces within the cold trap
Implementation Method 4
contaminants such as nitrogen, oxygen, carbon dioxide, argon that may be present in the cryogenic refrigerant are cryocondensed or cryoadsorbed on surfaces within the cold trap
Implementation Method 5
forming a first electrical potential of a first polarity on a plurality of discharge electrodes positioned in the fluid passage that extends from the at least one inlet to the at least one outlet of the electrostatic cryogenic cold trap; forming a second electrical potential of a second polarity on the plurality of collection electrodes
Data Source
AI summary
Systems and methods for improving the performance of dilution refrigeration systems are described. Electrostatic cryogenic cold traps employed in the helium circuit of a dilution refrigerator improve the removal efficiency of contaminants from the helium circuit. An ionization source ionizes at least a portion of a refrigerant that includes helium and number of contaminants. The ionized refrigerant passes through an electrostatic cryogenic cold trap that includes a number of surfaces at one or more temperatures along at least a portion of the fluid passage between the cold trap inlet and the cold trap outlet. A high voltage source coupled to the surfaces to causes a first plurality of surfaces to function as electrodes at a first potential and a second plurality of surfaces to function as electrodes at a second potential. As ionized contaminants release their charge on the electrodes, the contaminants bond to the electrodes.