CN-122015415-A - Systems and methods for reducing parasitic thermal loads from non-operational cryocoolers

Abstract

A superconducting machine system includes a superconducting machine. The superconducting machine system further includes a refrigerated container. The freezer encloses the superconducting electrical machine. The superconducting machine system further includes a vacuum vessel wall surrounding the freezer vessel. The superconducting machine system even further comprises a cryocooler coupled to the vacuum vessel wall, wherein the cryocooler is configured to cool the superconducting machine. The superconducting machine system further includes a system configured to remove helium gas from the cryocooler housing when the cryocooler is switched to the non-operational state to reduce helium gas pressure within the cryocooler, thereby minimizing parasitic heat load generated when the cryocooler is switched from the operational state to the non-operational state.

Inventors

• Ernst Wolfgang Stadtna
• WU ANBO
• V. K. Sony

Assignees

• 通用电气精准医疗有限责任公司

Dates

Publication Date

20260512

Application Date

20251021

Priority Date

20241108

Claims (20)

1. 1. A superconducting machine system, the superconducting machine system comprising: A superconducting machine; A freezer container surrounding the superconducting machine; a vacuum vessel wall surrounding the freezer vessel; A cryocooler coupled to the vacuum vessel wall, wherein the cryocooler is configured to cool the superconducting electrical machine, and A system configured to remove helium gas from within a cryocooler housing when the cryocooler is switched to a non-operational state to reduce helium gas pressure within the cryocooler, thereby minimizing parasitic thermal load generated when the cryocooler is switched from an operational state to the non-operational state.
2. 2. The superconducting machine system of claim 1 wherein the system includes a vacuum pump configured to remove the helium gas when the cryocooler is switched to the non-operational state until the helium gas pressure drops to a set threshold.
3. 3. The superconducting machine system of claim 2 wherein the set threshold is below 0.1 bar and above 10 -10 millibars.
4. 4. The superconducting machine system of claim 2 wherein the vacuum pump comprises a rough vacuum pump.
5. 5. The superconducting machine system of claim 2 wherein the vacuum pump comprises a turbo-mechanical pump.
6. 6. The superconducting machine system of claim 2 wherein the system is configured to first drain the helium gas from the cryocooler to reduce the helium gas pressure to a first set threshold when the cryocooler is switched to the non-operational state, and then the vacuum pump is configured to remove the helium gas until the helium gas pressure falls to a second set threshold that is lower than the first set threshold.
7. 7. The superconducting machine system of claim 1 comprising a pre-evacuated vacuum chamber configured to remove helium gas from the cryocooler housing when the cryocooler is switched to the non-operational state.
8. 8. The superconducting machine system of claim 1 wherein the superconducting electrical machine comprises a superconducting magnet.
9. 9. The superconducting machine system of claim 1 wherein the cryocooler is oriented at an angle when coupled to the vacuum vessel wall.
10. 10. The superconducting machine system of claim 1 wherein the cryocooler is a single stage cooler.
11. 11. The superconducting machine system of claim 1 wherein the cooling medium for the superconducting machine system is any other cryogen.
12. 12. The superconducting machine system of claim 1 wherein the superconducting electrical machine comprises a superconducting generator.
13. 13. A system for reducing parasitic thermal load from a non-operational cryocooler, the system comprising: a cryocooler configured to be coupled to a vacuum vessel wall, the vacuum vessel wall surrounding a freezer vessel, the freezer vessel surrounding a superconducting machine, wherein the cryocooler is configured to cool the superconducting machine; Vacuum pump, and A controller comprising a memory and a processing system comprising one or more processors, wherein the controller is configured to provide a control signal to the vacuum pump when the cryocooler is switched to a non-operational state, the control signal causing the vacuum pump to remove helium gas from within the cryocooler housing to reduce helium gas pressure within the cryocooler, thereby minimizing parasitic thermal load generated when the cryocooler is switched from an operational state to the non-operational state.
14. 14. The system of claim 13, further comprising one or more temperature sensors coupled to the cryocooler, wherein the controller is configured to receive feedback from the one or more temperature sensors, determine an amount of the parasitic thermal load generated when the cryocooler switches from the operating state to the non-operating state based on the feedback, determine a particular helium gas pressure to be achieved within the cryocooler based on the amount of the parasitic thermal load, and provide the control signal to the vacuum pump that causes the vacuum pump to remove the helium gas until the particular helium gas pressure is reached.
15. 15. The system of claim 13, wherein the controller is configured to provide the control signal to a valve when the cryocooler is switched to a non-operational state, the control signal causing initial venting of the helium gas from the cryocooler to reduce the helium gas pressure to a first set threshold, and then to provide the control signal to the vacuum pump when the cryocooler is switched to a non-operational state, the control signal causing the vacuum pump to remove the helium gas until the helium gas pressure falls to a second set threshold that is below the first set threshold.
16. 16. The system of claim 13, wherein the controller is configured to provide the control signal to the vacuum pump when the cryocooler is switched to a non-operational state, the control signal causing the vacuum pump to remove the helium gas until the helium gas pressure drops to a set threshold.
17. 17. The system of claim 16, wherein the set threshold is below 0.1 bar and above 10 -10 mbar.
18. 18. The system of claim 17, wherein the set threshold is between 10 -1 mbar and 10 -10 mbar.
19. 19. The system of claim 13, wherein the superconducting machine comprises a superconducting magnet.
20. 20. The system of claim 13, wherein the superconducting electrical machine comprises a superconducting generator.

Description

Systems and methods for reducing parasitic thermal loads from non-operational cryocoolers Statement regarding federally sponsored research and development The present invention was completed with U.S. government support under contract number U01 EB027696 awarded by the national institutes of health and human services. The government has certain rights in the invention. Background The subject matter disclosed herein relates to a system and method for reducing parasitic thermal loads from non-operational cryocoolers. Magnetic Resonance Imaging (MRI) is a medical imaging technique used in radiology to visualize detailed internal structures of a patient. MRI systems utilize superconducting magnets to generate a strong and uniform magnetic field in which a patient is placed. The superconducting magnet consists of individual superconducting magnet coils placed in a cryogenic liquid to maintain its superconductivity. The MRI system includes a cryocooler that provides cooling to balance the thermal load of the superconducting magnet so that no cryogen is lost. The cryocooler comprises a combination of a regenerator and a displacer to cool and recondense the gaseous cryogen. The thermal burden on the cryostat and magnet is much higher than expected whenever the cryocooler is off and not operating. The reason for this is a parasitic thermal load that is transferred by means of high power low temperature convection flowing within the cryocooler, which is transferred to the magnet through the cryocooler housing. Superconducting machines such as motors and generators also utilize cryocoolers. Disclosure of Invention The following sets forth an overview of certain embodiments disclosed herein. It should be understood that these aspects are presented merely to provide the reader with a brief summary of these certain embodiments and that these aspects are not intended to limit the scope of this disclosure. Indeed, the disclosure may encompass a variety of aspects that may not be set forth below. In one embodiment, a superconducting machine system is provided. The superconducting machine system includes a superconducting electrical machine. The superconducting machine system further includes a refrigerated container. The freezer encloses the superconducting electrical machine. The superconducting machine system further includes a vacuum vessel wall surrounding the freezer vessel. The superconducting machine system even further comprises a cryocooler coupled to the vacuum vessel wall, wherein the cryocooler is configured to cool the superconducting machine. The superconducting machine system further includes a system configured to remove helium gas from the cryocooler housing when the cryocooler is switched to the non-operational state to reduce helium gas pressure within the cryocooler, thereby minimizing parasitic heat load generated when the cryocooler is switched from the operational state to the non-operational state. In another embodiment, a system for reducing parasitic thermal load from a non-operational cryocooler is provided. The system includes a cryocooler configured to be coupled to a vacuum vessel wall that encloses a freezer container that encloses a superconducting machine, wherein the cryocooler is configured to cool the superconducting machine. The system also includes a vacuum pump. The system also includes a controller including a memory and a processing system including one or more processors. The controller is configured to provide control signals to the vacuum pump when the cryocooler is switched to the non-operational state, the control signals causing the vacuum pump to remove helium gas from the cryocooler housing to reduce helium gas pressure within the cryocooler, thereby minimizing parasitic thermal loads generated when the cryocooler is switched from the operational state to the non-operational state. In another embodiment, a method for reducing parasitic thermal load from a non-operational cryocooler is provided. The method includes switching the cryocooler from an operational state to a non-operational state, wherein the cryocooler is coupled to a vacuum vessel wall that encloses a refrigerated vessel that encloses the superconducting machine, and wherein the cryocooler is configured to cool the superconducting machine. The method further includes removing helium gas from within the cryocooler housing with a vacuum pump to reduce helium gas pressure within the cryocooler when the cryocooler is switched to a non-operational state, thereby minimizing parasitic thermal load generated when the cryocooler is switched from an operational state to a non-operational state. Drawings These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings in which like characters represent like parts throughout the drawings, wherein: FIG. 1 is a simplified block diagram of a porti