US3638440A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Closed-cycle electrocaloric refrigerator and method
Assignee: Corning Glass Works
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Filing: 1970-11-20
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Granted: 1972-02-01
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Expires: 1990-11-20
Abstract
Abstract A closed-cycle solid state refrigerator is disclosed that is capable of accurately and efficiently achieving extremely low temperatures. A second stage of the refrigerator comprises an evacuated chamber in which is disposed a solid state refrigerant that is connected by a first thermal valve to a first stage such as a cryostat and by a second thermal valve to a heat generating load that is to be cooled. The refrigerant consists of a polarizable electrocaloric material, the entropy of which can be substantially reduced by changing an electric field set up therein by a pair of electrodes disposed on opposite sides thereof. The refrigerant and the load are cooled by cycling the refrigerator through a given sequence of steps including opening and closing the thermal valves and changing the value of the applied electric field.
Inventors
- 👤 William N Lawless
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 09:41
CPC Classifications
F; F25; F25B; F25B21/00; F25B2321/00; F25B2321/001; Y; Y02; Y02B; Y02B30/00
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
176 words
A closed-cycle process for refrigerating a mass of material comprising the steps of providing an electrocaloric refrigerant, thermally connecting said refrigerant and material to a sink having a temperature of T1 so that said refrigerant and material are substantially cooled to temperature T1, thermally isolating said material, isothermally changing the polarization of said refrigerant toward a first state of polarization by applying thereto an electric field of intensity E1 to reduce the entropy of said refrigerant to a value S1, the condition of said refrigerant wherein the entropy thereof is at value S1, the temperature thereof is at value T1, and the electric field applied thereto is of value E1 constituting an initial condition, thermally isolating sAid refrigerant, adiabatically changing the polarization of said refrigerant to a second state of polarization by changing the intensity of said field from said intensity E1 to an intensity E2 to reduce the temperature of said refrigerant from said temperature T1 to a temperature T2, and thermally connecting said refrigerant to said material to decrease the temperature of said material.
Claim 2
Dependent Claim
176 words
A closed-cycle process for refrigerating a mass of material comprising the steps of providing an electrocaloric refrigerant, thermally connecting said refrigerant and material to a sink having a temperature of T1 so that said refrigerant and material are substantially cooled to temperature T1, thermally isolating said material, isothermally changing the polarization of said refrigerant toward a first state of polarization by applying thereto an electric field of intensity E1 to reduce the entropy of said refrigerant to a value S1, the condition of said refrigerant wherein the entropy thereof is at value S1, the temperature thereof is at value T1, and the electric field applied thereto is of value E1 constituting an initial condition, thermally isolating sAid refrigerant, adiabatically changing the polarization of said refrigerant to a second state of polarization by changing the intensity of said field from said intensity E1 to an intensity E2 to reduce the temperature of said refrigerant from said temperature T1 to a temperature T2, and thermally connecting said refrigerant to said material to decrease the temperature of said material.
Claim 3
Dependent Claim
22 words
The process of claim 1 wherein, after the step of thermally connecting said refrigerant to said material, said initial condition is reestablished.
Claim 4
Dependent Claim
75 words
The process of claim 2 wherein said step of reestablishing said initial condition comprises changing said field from said intensity E2 to an intensity E3 such that said refrigerant absorbs heat from said material substantially isothermally and the entropy of said refrigerant increases from said value S1 to a value S2, said change in field intensity from E2 to E3 being in the same direction as the change in field intensity from E1 to E2.
Claim 5
Dependent Claim
91 words
The process of claim 3 wherein said step of reestablishing said initial conditions further comprises adiabatically changing said field intensity to an intensity E4, said change in field intensity from E3 to E4 being in the direction opposite to the change in field intensity from E1 to E2, to increase the temperature of said refrigerant from said temperature T2 to said temperature T2, and isothermally changing said field from said intensity E4 to said intensity E1 to reduce the entropy of said refrigerant from said value S2 to said value S1.
Claim 6
Dependent Claim
29 words
The process of claim 4 wherein said field intensity E1 is sufficiently high to substantially produce saturation polarization of said refrigerant and said field intensity E3 is substantially 0.
Claim 7
Dependent Claim
13 words
The process of claim 4 wherein said field intensity E1 is substantially 0.
Claim 8
Dependent Claim
69 words
The process of claim 1 wherein said refrigerant is a material selected from the group consisting of electrically polar ion doped alkali-halides, electrically polar ion doped rutilelike crystalline materials, and glass ceramics consisting of a glass matrix, 0 to 5 percent by weight of at least one dopant, and at least 50 percent by weight of strontium titanate, wherein at least a portion of said strontium titanate is crystallized.
Claim 9
Dependent Claim
85 words
A closed-cycle refrigerator for refrigerating a mass of material, said refrigerator comprising an electrocaloric refrigerant, a sink for absorbing heat from said refrigerant at a substantially constant temperature within the electrocaloric refrigeration range of said refrigerant, means for thermally connecting and separating said refrigerant and said material, means for thermally connecting and separating said refrigerant and sink, means for thermally isolating said refrigerant and material when said last recited means thermally separate said refrigerant and sink, and means for electrically polarizing and depolarizing said refrigerant.
Claim 10
Dependent Claim
85 words
A closed-cycle refrigerator for refrigerating a mass of material, said refrigerator comprising an electrocaloric refrigerant, a sink for absorbing heat from said refrigerant at a substantially constant temperature within the electrocaloric refrigeration range of said refrigerant, means for thermally connecting and separating said refrigerant and said material, means for thermally connecting and separating said refrigerant and sink, means for thermally isolating said refrigerant and material when said last recited means thermally separate said refrigerant and sink, and means for electrically polarizing and depolarizing said refrigerant.
Claim 11
Dependent Claim
30 words
The refrigerator of claim 8 wherein said refrigerant consists essentially of a host crystalline material containing a polar ion dopant selected from the group consisting of OH and CN ions.
Claim 12
Dependent Claim
70 words
The refrigerator of claim 8 wherein said refrigerant consists of a material selected from the group consisting of electrically polar ion doped alkali-halides, electrically polar ion doped rutilelike crystalline materials, and glass ceramics consisting of a glass matrix, 0 to 5 percent by weight of at least one dopant, and at least 50 percent by weight of strontium titanate, wherein at least a portion of said strontium titanate is crystallized.
Claim 13
Dependent Claim
13 words
The refrigerator of claim 8 wherein said sink comprises a helium cryogenic refrigerator.
Claim 14
Dependent Claim
30 words
The refrigerator of claim 8 wherein said means for thermaLly connecting and separating said refrigerant and sink comprises a first magnetically actuated thermal valve connected between said refrigerant and sink.
Claim 15
Dependent Claim
30 words
The refrigerator of claim 8 wherein said means for thermally connecting and separating said refrigerant and material comprises a second magnetically actuated thermal valve connected between said refrigerant and material.
Claim 16
Dependent Claim
23 words
The refrigerator of claim 8 wherein said means for thermally isolating comprises a vacuum chamber in which said refrigerant and material are disposed.
Claim 17
Dependent Claim
35 words
The refrigerator of claim 8 wherein said means for polarizing and depolarizing said refrigerant comprises a variable high-voltage source, and a pair of electrodes separated by said refrigerant, said electrodes being connected across said source.
Claim 18
Dependent Claim
54 words
The refrigerator of claim 8 further comprising means for detecting the temperature of said refrigerant, and means responsively connected to said detecting means for changing the polarization of said refrigerant in response to a temperature rise therein, for maintaining said refrigerant at a substantially constant temperature while said refrigerant absorbs heat from said material.
Claim 19
Dependent Claim
61 words
The refrigerator of claim 12 wherein said means for thermally connecting and separating said refrigerant and material comprises a second magnetically actuated thermal valve connected between said refrigerant and material, and wherein said means for polarizing and depolarizing said refrigerant comprises a high-voltage source and a pair of electrodes separated by said refrigerant, said electrodes being connected across said high-voltage source.
Claim 20
Dependent Claim
23 words
The refrigerator of claim 17 wherein said means for thermally isolating comprises a vacuum chamber in which said refrigerant and material are disposed.
Claim 21
Dependent Claim
30 words
The refrigerator of claim 18 wherein said refrigerant consists essentially of a host crystalline material containing a polar ion dopant selected from the group consisting of OH and CN ions.
Claim 22
Dependent Claim
13 words
The refrigerator of claim 19 wherein said sink comprises a helium cryogenic refrigerator.
Claim 23
Dependent Claim
70 words
The refrigerator of claim 18 wherein said refrigerant consists of a material selected from the group consisting of electrically polar ion doped alkali-halides, electrically polar ion doped rutilelike crystalline materials, and glass ceramics consisting of a glass matrix, 0 to 5 percent by weight of at least one dopant, and at least 50 percent by weight of strontium titanate, wherein at least a portion of said strontium titanate is crystallized.
Claim 24
Dependent Claim
13 words
The refrigerator of claim 21 wherein said sink comprises a helium cryogenic refrigerator.
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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) | 1975-01-31 | 1975-08-02 | 1976-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-01-31 | 1979-08-02 | 1980-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-01-31 | 1983-08-02 | 1984-02-01 | $7700.00 | Window Closed / Lapsed |