Pre-cooling circuit and method for supplying helium refrigeration
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Solution Overview
Problem
Current pre-cooling systems for dilution cryostats, used in quantum computer research, have low efficiency and high energy consumption, leading to significant operating costs when multiple systems are operated, especially as the power requirement increases with the progress in quantum computer research.
Innovation Solution
A pre-cooling circuit that uses a helium cooling system with a multistage bath cooling process, including a feed line, return line, and an ejector to maintain helium in a supercritical state, avoiding two-phase mixtures and allowing for variable refrigeration supply to multiple dilution cryostats, with additional heat exchangers and a vacuum pump to achieve low temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple pulsation tube coolers are used to supply refrigeration to multiple dilution cryostats, then the refrigeration capacity is sufficient, but the energy consumption increases linearly and operating costs become significant
Solution Approach 1:
The patent merges multiple independent pre-cooling systems into a single shared pre-cooling circuit that can serve multiple dilution cryostats. The circuit includes a common feed line and return line with heat exchangers that can cool multiple consumers simultaneously, eliminating the need for separate pulsation tube coolers for each cryostat and thereby reducing total energy consumption.
Solution Approach 2:
The pre-cooling circuit is designed as a universal system that can supply refrigeration to one or multiple dilution cryostats depending on configuration. The system includes variable refrigeration supply capabilities through controllable valves and heat exchangers, allowing a single system to perform the function previously requiring multiple dedicated systems.
2Temperature
If helium is cooled to very low temperatures in the feed line, then the refrigeration efficiency improves, but a two-phase mixture occurs which is difficult to control
Solution Approach 1:
The patent maintains helium in a supercritical state by carefully controlling pressure and temperature parameters throughout the circuit. The helium is kept above its critical point (13.8 K, 2.27 MPa) in the feed line and heat exchangers, allowing efficient heat transfer without phase change. The ejector and expansion valve then control the phase transition only at the point of refrigeration delivery, making the process controllable rather than difficult.
Solution Approach 2:
The patent introduces an ejector as an intermediary device between the high-pressure supercritical helium supply and the low-temperature refrigeration point. The ejector uses expansion and throttling to convert the supercritical helium into a controlled two-phase mixture only where needed for cooling, mediating the transition and avoiding uncontrolled phase changes in the supply lines.
3Adaptability or versatility
If the refrigeration supply is made variable to accommodate different numbers of dilution cryostats, then the adaptability improves, but the device complexity increases
Solution Approach 1:
The patent incorporates dynamic control elements including valves (such as expansion valve 14 and control valve 26) and controllable heat exchangers that can adjust the refrigeration flow distribution in real-time. This allows the system to adapt to different numbers of active dilution cryostats and varying cooling demands without requiring complete system reconfiguration, achieving versatility through controlled dynamic operation rather than multiple fixed configurations.
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 enables efficient and variable low-temperature helium refrigeration supply, reducing energy consumption and operating costs by maintaining helium in a supercritical state and allowing for partial consumer operation, achieving temperatures below 3 K.
Implementation Method 1
an ejector with a drive flow opening, an intake opening and an ejection opening, wherein the drive flow opening is connected to the return line, the intake opening is connected to a top region of the second cooling bath container, and the ejection opening is connected to the top region of the first cooling bath container, wherein the ejector is designed to use helium returning from the refrigerating device through the return line as a drive flow to draw in helium vapor from the second cooling bath container and to raise it to the pressure of the first cooling bath container
Implementation Method 2
the feed line runs through a first heat exchanger located in a bottom region of the first cooling bath container and subsequently in the direction of the refrigerating device through a second heat exchanger located in a bottom region of the second cooling bath container
Implementation Method 3
a helium cooling system, which is designed to dissipate heat to the environment, to compress returning helium, and to feed the compressed helium into the feed line
Data Source
AI summary
A pre-cooling circuit for supplying helium refrigeration to at least one consumer to be cooled, comprising a feed line and a return line which are connected to one another via a refrigerating device, said refrigerating device being designed to exchange heat with the at least one consumer to be cooled; a helium cooling system, which is designed to dissipate heat to the environment, to compress helium flowing back and to feed the compressed helium into the feed line; a first and a second cooling bath container, the feed line running through a first heat exchanger located in a bottom region of the first cooling bath container and subsequently in the direction of the refrigerating device through a second heat exchanger located in a bottom region of the second cooling bath container.