Multi-layered electrocaloric heat pump systems and methods
In at least one illustrative embodiment, a cooling system includes a heat source, multiple electrocaloric material layers coupled to the heat source, and a heat sink coupled to the electrocaloric material layers. An electric field applied to each electrocaloric material layer is independently controllable. The electric field applied to each electrocaloric material layer is operable to move heat energy from the heat source to the heat sink during an interval, and to restore initial conditions of the electrocaloric material layers during a subsequent interval. The heat sink, the electrocaloric material layers, and the heat source may be bonded together. The electrocaloric material layers and the heat source may be bonded together, and the heat sink may be removably coupled to the electrocaloric material layers. Other embodiments are described and claimed.
1 . A cooling system comprising:
a heat source;
a plurality of electrocaloric material layers coupled to the heat source, wherein an electric field applied to each electrocaloric material layer is independently controllable; and
a heat sink coupled to the plurality of electrocaloric material layers;
wherein the electric field applied to each electrocaloric material layer is operated to: (i) move a first amount of heat energy from the heat source to the heat sink during a first interval and (ii) restore an initial condition of the plurality of electrocaloric material layers during a second interval after the first interval.
2 . The cooling system of claim 1 , wherein the plurality of electrocaloric material layers are separated by layers of electrically conductive materials.
3 . The cooling system of claim 1 , wherein the plurality of electrocaloric material layers are separated by layers of electrically insulative materials.
4 . The cooling system of claim 1 , wherein the plurality of electrocaloric material layers comprises lead magnesium niobate (PMN) or barium titanate (BT) and the heat sink comprises copper, silver, or aluminum.
5 . The cooling system of claim 1 , wherein the heat source comprises a silicon die.
6 . The cooling system of claim 1 , further comprising a controller coupled to the plurality of electrocaloric material layers and configured to independently control the electric field applied to each electrocaloric material layer.
7 . The cooling system of claim 1 , wherein the plurality of electrocaloric material layers comprises a first layer and a second layer, wherein the first layer is bonded to the heat sink and the second layer, and wherein the second layer is bonded to the first layer and the heat source.
8 . The cooling system of claim 7 , wherein:
during the first interval, (i) a first electric field applied to the first layer is increased from a first field strength to a second field strength thereby causing a temperature of the first layer to increase from an equilibrium temperature by a predetermined temperature delta and (ii) a second electric field applied to the second layer is decreased from the second field strength to the first field strength thereby causing a temperature of the second layer to decrease from the equilibrium temperature by the predetermined temperature delta;
during a first subinterval of the second interval, (i) the first electric field is decreased from the second field strength to the first field strength thereby causing the temperature of the first layer to decrease from the equilibrium temperature by the predetermined temperature delta and (ii) the second electric field is maintained; and
during a second subinterval of the second interval, (i) the first electric field is maintained and (ii) the second electric field is increased from the first field strength to the second field strength thereby causing the temperature of the second layer to increase from the equilibrium temperature by the predetermined temperature delta.
9 . The cooling system of claim 8 , wherein:
during a third subinterval of the second interval prior to the first subinterval, the first electric field is increased and the second electric field is increased; and
during a fourth subinterval of the second interval after the second subinterval, the first electric field is decreased and the second electric field is decreased.
10 . The cooling system of claim 8 , wherein the first interval lasts a predetermined time until the first amount of heat energy is transferred to the heat sink, and wherein each of the first subinterval and the second subinterval lasts until the heat sink, the plurality of electrocaloric material layers, and the heat source reach the equilibrium temperature.
11 . The cooling system of claim 10 , wherein the first interval lasts until a temperature maximum reaches an interface between the first layer and the heat sink.
12 . The cooling system of claim 1 , wherein a net heat transfer during the second interval between the heat source and the heat sink is zero.
13 . The cooling system of claim 1 , wherein the initial condition comprises a respective initial electric field strength for each layer of the plurality of electrocaloric material layers, and wherein the initial condition comprises an equilibrium temperature for the plurality of electrocaloric material layers.
14 . The cooling system of claim 1 , wherein the plurality of electrocaloric material layers comprises a first layer bonded to a second layer, wherein the first layer is detachably coupled to a first component of the heat sink and the heat source, and wherein the second layer is bonded to a second component of the heat sink and the heat source other than the first component.
15 . The cooling system of claim 14 ,
during the first interval, (i) the first component of the heat sink and the heat source is attached to the first layer, (ii) a first electric field applied to the first layer is increased from a first field strength to a second field strength thereby causing a temperature of the first layer to increase from an equilibrium temperature by a predetermined temperature delta, and (iii) a second electric field applied to the second layer is decreased from the second field strength to the first field strength thereby causing a temperature of the second layer to decrease from the equilibrium temperature by the predetermined temperature delta; and
during the second interval, (i) the first component of the heat sink and the heat source is detached from the first layer, (ii) the first electric field is decreased from the second field strength to the first field strength thereby causing the temperature of the first layer to decrease from the equilibrium temperature by the predetermined temperature delta and (ii) the second electric field is increased from the first field strength to the second field strength thereby causing a temperature of the second layer to increase from the equilibrium temperature by the predetermined temperature delta.
16 . The cooling system of claim 14 , wherein the first interval lasts a predetermined time until the first amount of heat energy is transferred to the heat sink, and wherein the second interval lasts until the plurality of electrocaloric material layers and the heat source reach the equilibrium temperature.
17 . The cooling system of claim 14 , wherein the first interval lasts until a temperature maximum reaches an interface between the first layer and the heat sink.
18 . The cooling system of claim 14 , further comprising an electrically conductive cantilever coupled to the heat sink, wherein the cantilever is moveable between a first position in which the cantilever contacts the first layer and a second position in which the cantilever is spaced apart from the first layer.
19 . The cooling system of claim 14 , further comprising an electrically conductive cantilever coupled to the heat sink, wherein the cantilever is bonded to the second layer, and wherein the cantilever is moveable between a first position in which the first layer contacts the heat source and a second position in which the first layer is spaced apart from the heat source.
20 . The cooling system of claim 14 , further comprising an electrically conductive cantilever coupled to the heat sink;
wherein the plurality of electrocaloric material layers further comprise a third layer bonded to the cantilever and a fourth layer bonded to the third layer;
wherein the cantilever is moveable between a first position in which the fourth layer contacts the first layer and a second position in which the fourth layer is spaced apart from the first layer.