US5402648A
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US
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Sealed dewar with separate circulation loop for external cooling at constant pressure
Assignee: Sumitomo SHI Cryogenics of America Inc
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Filing: 1993-07-01
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Granted: 1995-04-04
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Expires: 2013-07-01
Abstract
Abstract Apparatus and methods for low pressure cooling of superconducting magnets, for example, on a magnetic levitated train, through a separate circulation loop from a sealed, unvented thermal reservoir to provide a lightweight cooling system. In a second embodiment, forced flow cooling is directed to the superconducting magnets and shields through a separate circulation loop from a sealed thermal reservoir to further reduce the weight of the cooling system.
Inventors
- 👤 Ralph C. Longsworth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 02:09
CPC Classifications
F; F25; F25B; F25B9/00; F25D; F25D3/00; F25D3/10; Y; Y10; Y10S; Y10S505/00; Y10S505/825; Y10S505/888; Y10S505/897
Claims Analysis
Total Claims: 37
Claim 1
Independent Claim
102 words
A system for cooling an external load, comprising: a sealed unvented dewar containing a fixed quantity of a first cryogen that is to be periodically recooled; cooling loop means connecting said sealed dewar and said external load in a loop for circulating a second cryogen through said sealed dewar to be cooled therein by transferring heat to said first cryogen and to said external load to cool said external load; and pump means to circulate said second cryogen in said loop to said external load at a substantially constant pressure and at a flow rate whereby said external load is effectively cooled.
Claim 2
Independent Claim
102 words
A system for cooling an external load, comprising: a sealed unvented dewar containing a fixed quantity of a first cryogen that is to be periodically recooled; cooling loop means connecting said sealed dewar and said external load in a loop for circulating a second cryogen through said sealed dewar to be cooled therein by transferring heat to said first cryogen and to said external load to cool said external load; and pump means to circulate said second cryogen in said loop to said external load at a substantially constant pressure and at a flow rate whereby said external load is effectively cooled.
Claim 3
Dependent Claim
21 words
The system of claim 1 wherein said second cryogen is cooled by circulating through a heat exchanger within said sealed dewar.
Claim 4
Dependent Claim
30 words
The system of claim 2 wherein said pump means elevates the pressure of said second cryogen from about 0.3 MPa to about 0.4 MPa, said second cryogen being gaseous helium.
Claim 5
Dependent Claim
42 words
The system of claim 1 wherein said sealed dewar is filled with liquid helium having a temperature of about 4K and a pressure of about 0.1 MPa, which warms to a temperature of about 8K and a pressure of about 1.8 MPa.
Claim 6
Dependent Claim
26 words
The system of claim 1 wherein said sealed dewar is filled with a cryogen selected from the group comprising liquid helium, liquid hydrogen and liquid neon.
Claim 7
Dependent Claim
21 words
The system of claim 1 wherein said external load is at least one superconducting magnet and at least one warm shield.
Claim 8
Dependent Claim
23 words
The system of claim 1 wherein said cryogen in said sealed dewar is recooled by flowing cold cryogen from a separate storage tank.
Claim 9
Dependent Claim
52 words
The system of claim 2 wherein said heat exchanger for cooling said second cryogen in said sealed dewar has a warm end and a cold end, and said heat exchanger is oriented with said warm end at a top of said dewar and said cold end at a bottom of said dewar.
Claim 10
Dependent Claim
15 words
The system of claim 1 wherein the pump means is located within said sealed dewar.
Claim 11
Independent Claim
80 words
A method for cooling an external load, comprising the steps of: periodically cooling a sealed unvented dewar containing a fixed quantity of a first cryogen; circulating a second cryogen through a cooling loop to said sealed dewar to be cooled therein by said first cryogen and to said external load to cool said external load; and circulating said second cryogen to said external load at a substantially constant pressure and a flow rate whereby said external load is effectively cooled.
Claim 12
Independent Claim
80 words
A method for cooling an external load, comprising the steps of: periodically cooling a sealed unvented dewar containing a fixed quantity of a first cryogen; circulating a second cryogen through a cooling loop to said sealed dewar to be cooled therein by said first cryogen and to said external load to cool said external load; and circulating said second cryogen to said external load at a substantially constant pressure and a flow rate whereby said external load is effectively cooled.
Claim 13
Dependent Claim
26 words
The method of claim 10 including the step of cooling said second cryogen by circulating said second cryogen through a heat exchanger within said sealed dewar.
Claim 14
Dependent Claim
30 words
The method of claim 10 including the step of elevating the pressure of said second cryogen from about 0.3 MPa to about 0.4 MPa, said second cryogen being helium gas.
Claim 15
Dependent Claim
48 words
The method of claim 10 including the step of filling said sealed dewar with a first cryogen comprising liquid helium having a temperature of about 4K and a pressure of about 0.1 MPa and allowing it to warm to about 8K and a pressure of about 1.8 MPa.
Claim 16
Dependent Claim
29 words
The method of claim 10 including the step of filling said sealed dewar with a first cryogen selected from the group comprising liquid helium, liquid hydrogen and liquid neon.
Claim 17
Dependent Claim
29 words
The method of claim 10 including the step of elevating the pressure of said second cryogen by means of a pump in said cooling loop within said sealed dewar.
Claim 18
Independent Claim
67 words
A system for cooling an external load, comprising: a sealed unvented dewar containing a fixed quantity of a first cryogen that is to be periodically recooled; and cooling loop means connecting said sealed dewar and said external load in a loop for circulating a second cryogen at essentially constant pressure through said sealed dewar to be cooled and to said external load to cool said external load.
Claim 19
Independent Claim
67 words
A system for cooling an external load, comprising: a sealed unvented dewar containing a fixed quantity of a first cryogen that is to be periodically recooled; and cooling loop means connecting said sealed dewar and said external load in a loop for circulating a second cryogen at essentially constant pressure through said sealed dewar to be cooled and to said external load to cool said external load.
Claim 20
Dependent Claim
36 words
The system of claim 16 wherein said first cryogen is initially liquid helium having a temperature of about 4.2K and a pressure of 0.1 MPa, which warms to about 8K and a pressure of 1.8 MPa.
Claim 21
Dependent Claim
27 words
The system of claim 16 wherein said sealed dewar is filled with said first cryogen selected from the group comprising liquid helium, liquid hydrogen and liquid neon.
Claim 22
Dependent Claim
19 words
The system of claim 17 wherein said second cryogen is helium gas at a pressure of about 0.3 MPa.
Claim 23
Dependent Claim
21 words
The system of claim 19 wherein said helium gas is circulated in said loop means by a compressor at room temperature.
Claim 24
Dependent Claim
21 words
The system of claim 16 wherein said external load is at least one superconducting magnet and at least one cold shield.
Claim 25
Dependent Claim
63 words
The system of claim 21 further including: a cold box containing said sealed dewar containing said first cryogen and a reservoir of a third cryogen for cooling said at least one cold shield located adjacent said at least one superconducting magnet; and said cooling loop means passing through said reservoir to reduce the temperature of said second cryogen circulating through said closed loop.
Claim 26
Dependent Claim
79 words
The system of claim 22 wherein said cooling loop means includes a plurality of sections which carry said second cryogen in a path from said compressor located external to said cold box, through said reservoir, into at least one warm shield adjacent said at least one cold shield, back to said reservoir, to said at least one superconducting magnet, to said at least one cold shield, to said sealed dewar, and back through said compressor to complete said path.
Claim 27
Dependent Claim
48 words
The system of claim 23 wherein said cold box further includes first and second heat exchangers, and said second cryogen in said plurality of sections of said path of said cooling loop means passes through said first and second heat exchangers to transfer heat in said cold box.
Claim 28
Independent Claim
57 words
The method for cooling an external load, comprising the steps of: periodically cooling a sealed unvented dewar containing a fixed quantity of a first cryogen; and circulating a second cryogen at essentially constant pressure through a cooling loop connecting said sealed dewar, where said second cryogen is cooled, and said external load to cool said external load.
Claim 29
Independent Claim
57 words
The method for cooling an external load, comprising the steps of: periodically cooling a sealed unvented dewar containing a fixed quantity of a first cryogen; and circulating a second cryogen at essentially constant pressure through a cooling loop connecting said sealed dewar, where said second cryogen is cooled, and said external load to cool said external load.
Claim 30
Dependent Claim
50 words
The method of claim 25 including the step of filling said sealed dewar with a first cryogen of liquid helium having a temperature of about 4.2K and a pressure of about 0.1 MPa and allowing said first cryogen to warm to about 8K and a pressure of about 1.8 MPa.
Claim 31
Dependent Claim
29 words
The method of claim 25 including the step of filling said sealed dewar with a first cryogen selected from the group comprising liquid helium, liquid hydrogen and liquid neon.
Claim 32
Dependent Claim
25 words
The method of claim 27 including the step of selecting said second cryogen to be a helium gas at a pressure of about 0.3 MPa.
Claim 33
Dependent Claim
26 words
The method of claim 25 including the step of selecting said external load to be at least one superconducting magnet and at least one warm shield.
Claim 34
Dependent Claim
69 words
The method of claim 29 including the steps of: providing a cold box containing said sealed dewar holding said first cryogen, and containing a reservoir of a third cryogen for cooling said at least one warm shield located adjacent each of said at least one superconducting magnet; and passing said cooling loop through said reservoir to reduce the temperature of said second cryogen circulating through said closed cooling loop.
Claim 35
Dependent Claim
63 words
The method of claim 30 including the steps of: circulating said second cryogen through said cooling loop in a path from said compressor located external to said cold box, through said reservoir, into said at least one warm shield, back to said reservoir, to said at least one superconducting magnet, to said sealed dewar and back through said compressor to complete said path.
Claim 36
Dependent Claim
26 words
The system of claim 1 wherein said pump means elevates said second cryogen to a selected pressure that enhances heat transfer characteristics of the second cryogen.
Claim 37
Dependent Claim
30 words
The method of claim 10, further comprising the step of raising the pressure of said second cryogen to a selected pressure that enhances heat transfer characteristics of said second cryogen.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1998-04-03 | 1998-10-03 | 1999-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-04-03 | 2002-10-03 | 2003-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-04-03 | 2006-10-03 | 2007-04-04 | $7700.00 | Window Closed / Lapsed |