JT-Aided Stirling Cooler for Fast Cryogenic Ready Time
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Solution Overview
Problem
Current cryogenic coolers, such as Joule-Thomson and Stirling coolers, face limitations in flight vehicle applications due to logistical constraints, contamination risks, and the need for compromise between quick ready times and long operating durations, leading to significant maintenance and performance trade-offs.
Innovation Solution
A cooling system integrating a Joule-Thomson valve and counter-flow heat exchanger with a Stirling cooler's cold finger, utilizing an adapter for efficient heat transfer and minimizing size and thermal mass, allowing for quick ready times and extended operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of time
If Joule-Thomson cooler is used, then quick ready time is achieved, but operating duration is limited due to pressurized gas supply constraints
Solution Approach 1:
The system is divided into two distinct cooling subsystems: a Joule-Thomson cooler for rapid initial cooling and a Stirling cooler for sustained long-term operation. This segmentation allows each subsystem to operate in its optimal performance regime, with the JT valve providing quick ready time and the Stirling cooler providing extended duration without requiring large pressurized gas supplies.
Solution Approach 2:
The Joule-Thomson cooler performs preliminary cooling action to rapidly bring the thermal load to near-operating temperature. This preliminary action eliminates the long ready time associated with Stirling coolers alone, while the Stirling cooler then takes over for sustained operation, combining the advantages of both approaches.
2Device complexity
If Joule-Thomson cooler with fixed orifice is used, then simple structure is achieved, but reliability deteriorates due to contamination blocking the orifice
Solution Approach 1:
A filter is introduced as an intermediary component between the pressurized gas supply and the JT valve orifice. This filter prevents contamination from reaching and blocking the orifice, thereby maintaining reliability without significantly increasing system complexity. The filter can be easily replaced during maintenance.
Solution Approach 2:
The system uses a replaceable filter element that can be periodically swapped out when contaminated, rather than attempting to protect the critical orifice indefinitely. This approach maintains high reliability through simple maintenance procedures without adding complex protection mechanisms.
3Duration of action of moving object
If Stirling cooler is used, then long operating duration is achieved, but ready time increases due to slow thermal response
Solution Approach 1:
The system merges a Joule-Thomson cooler and a Stirling cooler into a single integrated cooling system. The JT cooler handles the rapid initial cooling phase to achieve quick ready time, while the Stirling cooler handles the sustained cooling phase for long operating duration. This combination eliminates the need to choose between the two technologies.
Solution Approach 2:
The system dynamically switches between two cooling modes: using the JT valve for rapid cooling when quick ready time is needed, and transitioning to the Stirling cooler for sustained operation. This dynamic operation allows the system to optimize performance based on the operational phase, achieving both quick ready time and long duration.
4Duration of action of moving object
If pressurized gas supply is increased for Joule-Thomson cooler, then operating duration is extended, but weight and volume increase
Solution Approach 1:
The Stirling cooler acts as an intermediary that extends operating duration without requiring additional pressurized gas supply. By transitioning to electrically-driven Stirling cooling after the initial JT cooling phase, the system achieves extended operation using only small amounts of pressurized gas, dramatically reducing the weight and volume of gas containers needed.
Solution Approach 2:
The system replaces the mechanical pressurized gas supply system with an electrically-driven Stirling cooler for the sustained operation phase. This substitution eliminates the need for large, heavy pressurized gas containers while maintaining long operating duration, as the Stirling cooler can run continuously on electrical power.
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 rapid cooling of thermal loads while maintaining long-term operation, reducing maintenance needs and enhancing system performance by leveraging the quick cooling power of Joule-Thomson systems and the efficiency of Stirling coolers.
Implementation Method 1
Joule-Thomson cooler is a device that produces liquid refrigerant by use of a valve (known in the art as a 'Joule-Thomson valve') and counter flow heat exchanger. High-pressure gas is allowed to expand through the valve via an irreversible throttling process in which enthalpy is conserved, resulting in lowering of its temperature.
Implementation Method 2
The counter-flow heat exchanger transfers heat from the high-pressure incoming gas to the cooled exiting gas to decrease the enthalpy of the incoming gas and enable liquid production.
Implementation Method 3
A Stirling cycle cooler is an efficient and compact closed-cycle, electrically-driven cryogenic cooling device using a repeating reversible expansion of a gas.
Implementation Method 4
The regenerative heat exchanger (regenerator) is included in the expansion piston to thermally isolate gas at the compressor headspace from gas at the expansion headspace.
Implementation Method 5
an adapter positioned between the cold finger and the second heat exchanger, the adapter operable to transfer heat from a thermal load to both the cold finger and the refrigerant emitted from the Joule-Thomson valve
Data Source
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AI summary
An apparatus includes a chamber (214, 300), a first heat exchanger (221), an adapter (212, 312), and a second heat exchanger (223). The first heat exchanger includes a cold finger (206, 306) positioned within the chamber. The second heat exchanger is positioned around the adapter and within the chamber. The second heat exchanger is a counter flow heat exchanger to precool refrigerant entering a Joule-Thomson valve (224, 324). The adapter is positioned between the cold finger and the second heat exchanger. The adapter transfers heat from a thermal load to both the cold finger and the refrigerant emitted from the Joule-Thomson valve.