Refrigeration system including micro compressor-expander thermal units
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Solution Overview
Problem
Conventional refrigeration cycles have low thermodynamic efficiency due to poor heat transfer during gas compression, leading to increased work input and reduced cooling power, with limited work recovery from expansion processes.
Innovation Solution
The implementation of directly coupled micro compressor-expander units (MCEUs) with electromagnetic or pneumatic mechanisms for simultaneous nearly isothermal polytropic compression and expansion, allowing for work input recovery during the refrigeration cycle, using radial motion of helium gas to maintain constant thermal mass and employing magnetic drives for efficient piston movement.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional gas compression is used in refrigeration cycles, then the compression process can be completed, but heat transfer is poor and thermodynamic efficiency is low
Solution Approach 1:
The system divides the compression process into multiple small stages using an array of micro-compressors, each handling a portion of the total gas flow. This segmentation allows each micro-compressor to operate more efficiently with better heat transfer characteristics, resolving the contradiction between completing compression and maintaining thermodynamic efficiency.
Solution Approach 2:
The patent replaces conventional mechanical compression with electromagnetic compression in micro-compressors. This substitution enables isothermal or near-isothermal compression by providing precise control over the compression process, significantly improving heat transfer and thermodynamic efficiency while reducing work input.
2Power
If gas expansion is used to produce cooling effect, then cooling power increases, but work recovery is limited
Solution Approach 1:
The patent merges the compressor and expander functions into a single integrated device where the expander is directly coupled to the compressor. This allows the work produced during gas expansion to be directly recovered and used to drive the compression process, maximizing work recovery while maintaining high cooling power.
Solution Approach 2:
The expander-driven compressor system enables the refrigeration cycle to be self-sufficient by using the work generated during expansion to power the compression process. This self-service mechanism maximizes work recovery and reduces external energy input requirements.
3Loss of energy
If work recovery from expansion is implemented, then thermodynamic efficiency improves, but device complexity increases
Solution Approach 1:
By merging the compressor and expander into a single integrated unit with direct coupling, the patent achieves work recovery without requiring separate, complex systems. The direct coupling allows mechanical energy transfer between compression and expansion stages, improving thermodynamic efficiency while minimizing additional device complexity.
Solution Approach 2:
The integrated compressor-expander unit performs multiple functions simultaneously: compression, expansion, work recovery, and heat transfer. This multi-functionality reduces the need for separate components and simplifies the overall system architecture while maintaining improved thermodynamic efficiency.
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 approach enhances refrigeration efficiency by distributing work input across a wide temperature range, achieving significant work recovery and reducing net work input, thereby improving the ratio of cooling power to work input, even at cryogenic temperatures.
Implementation Method 1
An array of micro compressor-expander units (MCEUs) with electromagnetic or pneumatic mechanisms for producing linear reciprocating motion of a piston
Implementation Method 2
nearly isothermal polytropic compression and synchronous nearly isothermal polytropic expansion of a working gas
Implementation Method 3
nearly isothermal polytropic compression
Implementation Method 4
A heat transfer fluid (HTF) is driven through a heat transfer circuit formed by the first and second heat transfer chambers
Implementation Method 5
using radial motion of helium gas to maintain constant thermal mass
Implementation Method 6
MCEUs with electromagnetic or pneumatic mechanisms for producing linear reciprocating motion of a piston
Data Source
AI summary
An active gas regenerative refrigerator includes a plurality of compressor-expander units, each having a hermetic cylinder with a drive piston configured to be driven reciprocally therein, and a quantity of working fluid in each end of the cylinder. A piston seal in a central portion of the cylinder prevents passage of the working fluid between ends of the cylinder. Movement of the piston to a first extreme results in radial compression of one of the quantities of working fluid in a cylindrical gap formed between one end of the piston and an inner surface of the cylinder, while the other quantity is expanded in the opposite end of the cylinder. The piston includes a plurality of magnets arranged in pairs, with magnets of each pair positioned with like-poles facing each other. A piston drive is configured to couple with transverse magnetic flux regions formed by the magnets.