Cryogenic refrigeration device
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Solution Overview
Problem
Existing cryogenic refrigeration devices face limitations in achieving low temperatures, reliability, and maintenance-free operation due to issues with regenerative and reverse Brayton cycles, such as low performance at low temperatures, oil usage, short service life, and inefficiency.
Innovation Solution
A cryogenic refrigeration device utilizing a recuperative thermodynamic cycle with a linear piston compressor, expander, and regulating valves actuated by linear motors, eliminating oil contact and incorporating counter-flow heat exchangers for efficient heat transfer and low-temperature operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a regenerative thermodynamic cycle (Stirling or Pulse-Tube type) is used, then the device can operate at cryogenic temperatures, but the performance is low at temperatures below 30K due to low thermal capacity of regenerator materials
Solution Approach 1:
The patent changes the thermodynamic cycle parameters from regenerative to recuperative, and modifies the working fluid parameters (using helium or hydrogen with specific pressure and temperature ranges) to achieve optimal performance at temperatures below 30K where regenerative cycles fail due to low thermal capacity materials
2Temperature
If a regenerative thermodynamic cycle is used, then cryogenic cooling is achieved, but it is difficult to connect the refrigerator thermally to the system to be cooled and to the heat removal system
Solution Approach 1:
The patent segments the thermal connection system into separate heat exchangers: a first heat exchanger for thermal connection to the system to be cooled, and a second heat exchanger for heat removal, allowing independent optimization and easier integration with external systems
3Power
If a reverse Brayton cycle with lubricated screw compressor is used, then compression is achieved, but oil must be used to cool and lubricate the compressor requiring cycle gas de-oiling operation after compression
Solution Approach 1:
The patent extracts and eliminates the oil lubrication system entirely by using a linear piston compressor with magnetic bearings that operates without lubrication, removing the source of oil contamination from the cryogenic cycle
Solution Approach 2:
The patent replaces the mechanical screw compressor with lubrication system with a linear piston compressor using magnetic bearings, substituting mechanical friction-based compression with electromagnetic field-based actuation that requires no lubricating oil
4Power
If a reverse Brayton cycle with lubricated screw compressor is used, then compression is achieved, but the service life is relatively short due to compression technology and leaks at the compressor level
Solution Approach 1:
The patent replaces the mechanical screw compressor with multiple seals and moving parts with a linear piston compressor using magnetic bearings, eliminating mechanical contact and friction that cause wear and leaks, thereby extending service life and improving reliability
5Object-generated harmful factors
If a reverse Turbo-Brayton cycle with centrifugal compressors is used, then dry compression is achieved, but the device is poorly adapted to low thermal inputs due to difficulty in miniaturizing turbomachines
Solution Approach 1:
The patent replaces complex centrifugal turbomachines with linear piston compressors actuated by linear motors, maintaining oil-free operation while enabling compact design suitable for low thermal input applications
Solution Approach 2:
The patent transitions from rotational centrifugal compression to linear reciprocating compression, changing the dimensional mode of operation from rotational to linear motion, enabling miniaturization and adaptation to low thermal inputs
6Object-generated harmful factors
If centrifugal compressors are used, then dry compression is achieved, but the compression rates achievable at each stage are relatively low due to low molar mass of available gases at cryogenic temperature
Solution Approach 1:
The patent replaces centrifugal compressors with linear piston compressors that can achieve higher compression ratios per stage by directly controlling piston displacement, overcoming the limitation of low compression rates inherent in centrifugal designs for low molar mass gases
Solution Approach 2:
The patent uses linear motors to dynamically control the piston motion and compression process, allowing optimization of compression rates for different operating conditions and gas types, achieving higher productivity than fixed-speed centrifugal compressors
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 solution achieves very low temperatures (4 K), high compression rates, increased efficiency, reduced maintenance, and extended service life, while eliminating oil usage and allowing for easy integration with cooling systems, enhancing reliability and adaptability.
Implementation Method 1
the compression portion comprises at least one compressor with a linear piston driven by a linear motor, the expansion portion comprises at least one expander with a linear piston
Implementation Method 2
incorporating counter-flow heat exchangers for efficient heat transfer
Implementation Method 3
the working circuit comprises a phase separator arranged downstream of at least one regulating valve in order to liquefy at least one part of the working fluid
Data Source
AI summary
Cryogenic refrigeration device comprising a working circuit intended to cool a working fluid circulating in the said circuit, the working circuit comprising, arranged in series in a loop: a compression portion, a cooling portion, a portion with valve(s), an expansion portion and a reheating portion, in order to subject the working fluid to a recuperative working cycle comprising compression, then cooling, then expansion and then reheating to prepare for a new cycle, wherein the compression portion comprises at least one compressor having a linear piston driven by a linear motor, the expansion proportion comprises at least one expander with a linear piston, the portion with valve(s) comprises at least one regulating valve linearly actuated by a linear motor and controlled in order to supply or extract the working fluid from the at least one expansion piston.