Apparatus and method for controlling a cryogenic cooling system
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Solution Overview
Problem
Current mechanical refrigerators have unsatisfactory thermodynamic coefficients of performance and cooling efficiency, requiring significant electrical power to achieve low temperatures, and have long cooling times due to suboptimal frequency control of cyclical gas pressure in cryogenic cooling systems.
Innovation Solution
Implementing a control system that modulates the frequency of cyclical gas pressure in mechanical refrigerators based on pressure feedback from supply or return gas lines, using pressure sensors and potentially temperature sensors to optimize frequency according to the cooling cycle, allowing for real-time adjustments to maintain efficient operation and reduce cooling time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the frequency of cyclical gas pressure is kept constant in mechanical refrigerators, then the system operation is simple, but the cooling efficiency is unsatisfactory and cooling time is long
Solution Approach 1:
The patent applies feedback control by monitoring the pressure differential across the heat exchanger and using this information to dynamically adjust the compressor frequency. The control system continuously measures the pressure difference between the high-pressure and low-pressure sides of the heat exchanger, compares it to optimal values, and modifies the compressor operating frequency accordingly to maximize cooling efficiency at different temperature stages.
Solution Approach 2:
The patent implements dynamic frequency adjustment of the compressor based on real-time pressure differential measurements. Instead of operating at a fixed frequency, the compressor frequency is continuously varied to match the thermal conditions of the mechanical refrigerator, allowing optimal heat transfer coefficients to be maintained throughout the cooling process from room temperature to cryogenic temperatures.
2Power
If higher electrical power is supplied to mechanical refrigerators, then cooling power increases, but the thermodynamic coefficient of performance deteriorates
Solution Approach 1:
The patent changes the operating parameters of the compressor dynamically by adjusting frequency based on temperature and pressure differential conditions. This allows the system to operate at optimal points across the entire temperature range, extracting maximum cooling power for each unit of electrical power consumed, thereby improving the thermodynamic coefficient of performance while maintaining high cooling power output.
Solution Approach 2:
The patent utilizes periodic compression and expansion cycles of the working gas, with the period (frequency) being dynamically adjusted. By optimizing the periodic action frequency at each temperature stage, the system achieves efficient heat transfer and maximizes cooling power output relative to the electrical power input, improving overall thermodynamic efficiency.
3Temperature
If the cooling cycle progresses from room temperature to low temperature, then the temperature is reduced as required, but the optimum frequency for heat transfer changes and reduces efficiency
Solution Approach 1:
The patent implements dynamic frequency adjustment that tracks the changing thermal conditions as the mechanical refrigerator cools from room temperature to cryogenic temperatures. The compressor frequency is continuously modified to maintain optimal heat transfer coefficients at each temperature stage, preventing efficiency degradation that would occur with fixed-frequency operation.
Solution Approach 2:
The system uses feedback from pressure differential measurements across the heat exchanger to determine the current thermal state of the mechanical refrigerator. This feedback information is used to adjust the compressor frequency in real-time, ensuring that the optimum frequency for heat transfer is maintained throughout the entire cooling cycle from ambient to 4K temperatures.
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 cooling efficiency by up to 35% and reduces cooling time, maintaining pressures within a predetermined range to prevent gas loss and optimize helium usage, while avoiding direct sensing of the cooled environment.
Implementation Method 1
pressure sensing apparatus may comprise a pressure sensor such as a pressure transducer for monitoring the pressure in at least one of the supply or returning gas lines
Implementation Method 2
CCRs operate upon a principle of using the cooling which is associated with the work of compression and expansion of a working gas coolant
Implementation Method 3
CCRs operate upon a principle of using the cooling which is associated with the work of compression and expansion of a working gas coolant
Data Source
Figure 1~2
Figure 3
AI summary
Apparatus for controlling a cryogenic cooling system is described. A supply gas line (3A) and a return gas line (3B) are provided which are coupled to a compressor (1) and to a mechanical refrigerator (2) via a coupling element (4). The coupling element is in gaseous communication with the supply (2A) and return gas lines and supplies gas to the mechanical refrigerator (2). The pressure of the supplied gas is modulated by the coupling element in a cyclical manner. A pressure sensing apparatus (6) monitors the pressure in at least one of the supply and return gas lines. A control system (5) is used to modulate the frequency of the cyclical gas pressure supplied by the coupling element in accordance with the pressure monitored by the pressure sensing apparatus. An associated method of controlling such a system is also described.