Electrocaloric effect heat transfer device dimensional stress control

Patent metadata

Field	Value
Publication number	US-9310109-B2
Application number	US-201414259663-A
Country	US
Kind code	B2
Filing date	Apr 23, 2014
Priority date	Sep 21, 2011
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

Technologies are generally described herein for electrocaloric effect heat transfer devices and methods effective to facilitate thermal energy transfer while mitigating mechanical stresses caused by expansion or contraction of electrocaloric effect material layers during thermal energy transfer operations. Some example heat transfer devices may include heat transfer stacks with at least two electrocaloric effect materials. Expanding electrocaloric effect material and contracting electrocaloric effect material are utilized to cancel the aggregate longitudinal dimensional change during application of an electric field. Some example heat transfer devices may utilize segmented electrocaloric effect material layers with stress relief gaps separating segments to mitigate delamination stress caused by lateral expansion or contraction of the electrocaloric effect material.

First claim

What is claimed is:

1. A method to transfer thermal energy from a heat source to a heat dump, the method comprising:
applying at least one electric field across a first electrocaloric effect material layer and across a second electrocaloric effect material layer of a heat transfer device in thermal contact with the heat source and the heat dump; and
in response to the applied at least one electric field, transferring thermal energy between the first electrocaloric effect material layer and the second electrocaloric effect material layer in a direction from the heat source toward the heat dump while restricting thermal energy transfer in a direction from the heat dump toward the heat source and at least partially canceling a dimensional change of the first electrocaloric effect material layer due to expansion by a dimensional change of the second electrocaloric effect material layer due to contraction so as to maintain an approximate total length of the heat transfer device.

2. The method of claim 1 , wherein the approximate total length of the heat transfer device corresponds to a fixed distance between the heat source and the heat dump.

3. The method of claim 1 , wherein applying the at least one electric field across the first electrocaloric effect material layer and across the second electrocaloric effect material layer comprises:
applying an electric field across a plurality of first electrocaloric effect material layers effective to provide an aggregate longitudinal expansion distance that includes as a contribution the dimensional change of the first electrocaloric effect material layer due to expansion; and
applying the electric field across a plurality of second electrocaloric effect material layers to provide an aggregate longitudinal contraction distance that is substantially equivalent to the aggregate longitudinal expansion distance, wherein the aggregate longitudinal contraction distance includes as a contribution the dimensional change of the second electrocaloric effect material layer due to contraction.

4. The method of claim 3 , wherein applying the electric field across the plurality of first electrocaloric effect material layers and across the plurality of second electrocaloric effect material layers comprises:
applying a first voltage across the plurality of first electrocaloric effect material layers effective to provide the aggregate longitudinal expansion distance; and
applying a second voltage across the plurality of second electrocaloric effect material layers effective to provide the aggregate longitudinal contraction distance,
wherein the first voltage and the second voltage are determined such that the aggregate longitudinal contraction distance is approximately equivalent to the aggregate longitudinal expansion distance.

5. The method of claim 4 , wherein the first voltage is different than the second voltage.

6. The method of claim 3 , wherein the electric field comprises one of: an oscillating voltage, a pulsed signal, a pulsed direct current (DC) voltage, an alternating current (AC) voltage, a ramped signal, a sawtooth signal, or a triangular signal.

7. The method of claim 1 , wherein applying the at least one electric field across the first electrocaloric effect material layer and across the second electrocaloric effect material layer comprises simultaneously applying the at least one electric field across the first electrocaloric effect material layer and across the second electrocaloric effect material layer.

8. A method to transfer thermal energy from a heat source to a heat dump through a heat transfer device, the method comprising:
expanding a first electrocaloric effect material layer and contracting a second electrocaloric effect material layer of the heat transfer device, wherein the heat transfer device is in thermal contact with the heat source and the heat dump; and
transferring thermal energy between the first electrocaloric effect material layer and the second electrocaloric effect material layer in a direction from the heat source toward the heat dump while restricting thermal energy transfer in a direction from the heat dump toward the heat source and at least partially canceling expansion of the first electrocaloric effect material layer by contraction of the second electrocaloric effect material layer so as to maintain an approximate total length of the heat transfer device.

9. The method of claim 8 , wherein the approximate total length of the heat transfer device corresponds to a fixed distance between the heat source and the heat dump.

10. The method of claim 8 , wherein:
expanding the first electrocaloric effect material layer comprises applying a first electric field across the first electrocaloric effect material layer; and
contracting the second electrocaloric effect material layer comprises applying a second electric field across the second electrocaloric effect material layer.

11. The method of claim 10 , wherein applying the first electric field across the first electrocaloric effect material layer comprises applying the first electric field across a plurality of first electrocaloric effect material layers effective to provide an aggregate longitudinal expansion distance that includes as a contribution an expansion distance of the first electrocaloric effect material layer.

12. The method of claim 11 , wherein applying the second electric field across the second electrocaloric effect material layer comprises applying the second electric field across a plurality of second electrocaloric effect material layers to provide an aggregate longitudinal contraction distance that includes as a contribution a contraction distance of the second electrocaloric effect material layer.

13. The method of claim 10 , wherein applying the first electric field across the first electrocaloric effect material layer comprises applying a first voltage across a plurality of first electrocaloric effect material layers effective to provide an aggregate longitudinal expansion distance that includes as a contribution an expansion distance of the first electrocaloric effect material layer.

14. The method of claim 13 , wherein:
applying the second electric field across the second electrocaloric effect material layer comprises applying a second voltage across a plurality of second electrocaloric effect material layers effective to provide an aggregate longitudinal contraction distance that includes as a contribution a contraction distance of the second electrocaloric effect material layer; and
the first voltage and the second voltage are determined such that the aggregate longitudinal contraction distance is approximately equivalent to the aggregate longitudinal expansion distance.

15. The method of claim 14 , wherein applying a first value of the first voltage is not equal to applying a second value of the second voltage.

16. The method of claim 10 , wherein applying the first electric field or the second electric field comprises applying one of: an oscillating voltage, a pulsed signal, a pulsed direct current (DC) voltage, an alternating current (AC) voltage, a ramped signal, a sawtooth signal, or a triangular signal.

17. A method to transfer heat through a heat transfer device between a heat source and a heat dump, the method comprising:
applying a first electric field to a first electrocaloric effect material configured to expand and to change temperature of the first electrocaloric effect material in response to application of the first electric field;
applying a second electric field to a second electrocaloric effect material configured to

Assignees

• Empire Technology Dev Llc

Inventors

• Kruglick Ezekiel

Classifications

• Y02B30/66

  Cross-Sectional Technologies · mapped topic

• F25B21/00 Primary

  Machines, plants or systems, using electric or magnetic effects · CPC title

• F25B2321/001

  by using electro-caloric effects · CPC title

• Y02B30/00

  Energy efficient heating, ventilation or air conditioning [HVAC] · CPC title