Device and method for generating a second temperature variation from a first temperature variation

Patent metadata

Field	Value
Publication number	US-9612040-B2
Application number	US-201214362285-A
Country	US
Kind code	B2
Filing date	Nov 29, 2012
Priority date	Dec 2, 2011
Publication date	Apr 4, 2017
Grant date	Apr 4, 2017

Abstract

A device for generating a second temperature variation ΔT 2 from a first use temperature variation ΔT 1 , includes an elastocaloric material layer, having an internal temperature which is able to vary by ΔT 2 in response to a given mechanical stress variation Δσ applied to the elastocaloric material layer. The variation Δσ being induced by the first use temperature variation ΔT 1 There is a suspended element in mechanical contact with the elastocaloric material layer so as to apply to this layer a mechanical stress that varies in response to the use temperature variation ΔT 1 . The suspended element is arranged so as to make the mechanical stress applied to the elastocaloric material layer vary by Δσ in response to the temperature variation ΔT 1 , to generate the second temperature variation ΔT 2 .

First claim

The invention claimed is:

1. A device for generating a second temperature variation ΔT 2 from a first use temperature variation ΔT 1 , comprising:
an elastocaloric material layer having an internal temperature of which is able to vary by ΔT 2 in response to a given mechanical stress variation Δσ applied to the elastocaloric material layer, the given variation Δσ being induced by the first use temperature variation ΔT 1 ,
a suspended element in mechanical contact with the elastocaloric material layer so as to apply to this layer a mechanical stress that varies in response to the use temperature variation ΔT 1 ,
wherein the suspended element is arranged so as to make the mechanical stress applied to the elastocaloric material layer vary by Δσ in response to the temperature variation ΔT 1 , to generate the second temperature variation ΔT 2 .

2. The device as claimed in claim 1 , wherein the internal temperature of the elastocaloric material is capable of varying by at least 1° C. in response to the given mechanical stress variation Δσ and the suspended element is formed so as to make the mechanical stress applied to the elastocaloric material layer vary by at least Δσ MPa in response to the use temperature variation ΔT 1 .

3. The device as claimed in claim 2 , wherein the variation ΔT 1 is greater than 10° C.

4. The device as claimed in claim 3 , wherein the variation Δσ in response to the variation ΔT 1 is of at least 1 MPa.

5. The device as claimed in claim 1 for generating electricity, wherein:
the device includes a recess delimited by, on one side, a hot wall to dissipate heat inside the recess and, on the opposite side, a cold wall having a lower temperature than the hot wall,
the suspended element is arranged inside the recess between the hot and cold walls, the suspended element being capable of deforming between a position closer to the hot wall to a position closer to the cold wall or conversely under the action of the variation ΔT 1 in the temperature of one of these walls,
the elastocaloric material is capable of transforming the mechanical stress variation that it undergoes when the suspended element deforms into a drop ΔT 2 in its internal temperature if the suspended element deforms from its closest position to the hot wall to its closest position to the cold wall under the action of the variation ΔT 1 or into a rise ΔT 2 in its internal temperature if the suspended element deforms from its closest position to the cold wall to its closest position to the hot wall under the action of the variation ΔT 1 , and
further including a transducer capable of converting the deformation of the suspended element into electrical energy.

6. The device as claimed in claim 5 , wherein the suspended element comprises a first and a second layer of material directly fastened one on top of the other with no degree of freedom, each of these layers being made of a material having a different thermal expansion coefficient from the other layer so as to form a bimetallic strip capable of deforming under the action of the temperature variation ΔT 1 .

7. The device as claimed in claim 6 , wherein one of the first and of the second layers is made of an elastocaloric material to form the elastocaloric material layer and the other of the first and of the second layers is made of material incapable of generating a temperature variation greater than 0.5° C. in response to the mechanical stress variation Δσ applied to this layer.

8. The device as claimed in claim 1 , wherein the device includes an actuator capable of making the suspended element oscillate between two states at a predetermined frequency for a given use temperature, and the elastocaloric material is capable of transforming the mechanical stress variation that it undergoes when the use temperature of the suspended element varies by ΔT 1 into a temperature variation ΔT 2 of opposite direction to the temperature variation ΔT 1 .

9. The device as claimed in claim 8 , wherein the elastocaloric material is capable of transforming the mechanical stress variation that it undergoes, when the use temperature of the suspended element varies by ΔT 1 , into a variation ΔT 2 of its internal temperature, the amplitude of which is equal to the amplitude of the variation ΔT 1 to within plus or minus 25%.

10. The device as claimed in claim 8 , wherein:
the suspended element comprises a first material having a first thermal expansion coefficient and two ends,
the device further includes a rigid substrate onto which the ends of the suspended element are fastened with no degree of freedom, the substrate being made of a second material having a second thermal expansion coefficient different from the coefficient of the first material so that the use temperature variation ΔT 1 causes the mechanical stress exerted on the suspended element to vary.

11. The device as claimed in claim 8 , wherein the elastocaloric material layer is interposed between at least one of said ends of the suspended element and the substrate.

12. The device as claimed in claim 1 , wherein the elastocaloric material layer is capable of transforming the stress variation that it undergoes, when the temperature of the suspended element varies by ΔT 1 , into a variation ΔT 2 of its internal temperature in the same direction as the first temperature variation ΔT 1 .

13. The device as claimed in claim 1 , wherein the elastocaloric material is chosen from the group composed of Cu 68.13 Zn 15.74 Al 16.13 , nickel and titanium alloys, FeRh alloys, PZT, and ferroelectric polymers.

14. The device as claimed in claim 1 , wherein the suspended element runs essentially in a main direction and the elastocaloric material layer covers at least 50% of the suspended element in the main direction.

15. A method for generating a second temperature variation ΔT 2 from a first use temperature variation ΔT 1 , this method comprising:
varying by ΔT 1 of the use temperature of a device including a suspended element, the suspended element being formed so as to make a mechanical stress applied to an elastocaloric material layer in mechanical contact with this suspended element vary by at least Δσ MPa in response to the use temperature variation ΔT 1 , and
in response, varying by at least Δσ MPa of the mechanical stress applied by the suspended element to the elastocaloric material layer in mechanical contact with this suspended element, and
transforming by the elastocaloric material layer, the mechanical stress variation into a variation ΔT 2 of its internal temperature that opposes, or conversely, increases the use temperature variation ΔT 1 .

16. The method as claimed in claim 15 , wherein the variation ΔT 1 is greater than 10° C.

17. The method as claimed in claim 15 , wherein the variation of ΔT 2 is greater than 10° C.

Assignees

• Commissariat L Energie Atomique Et Aux Energies Alternatives

Inventors

• Casset Fabrice

Classifications

• B81B2201/032

  Bimorph and unimorph actuators, e.g. piezo and thermo · CPC title

• F24J3/00 Primary

  Mechanical Engineering · mapped topic

• B81B3/0024 Primary

  Transducers for transforming thermal into mechanical energy or vice versa, e.g. thermal or bimorph actuators (electric motors using thermal effects H02N10/00) · CPC title

• H01L41/1136

  Electricity · mapped topic

• B81B2201/031

  Thermal actuators · CPC title