Electrocaloric heat transfer system

A heat transfer system cycles between a first mode where a heat transfer fluid is directed to a first electrocaloric module and from the first electrocaloric module to a heat exchanger to a second electrocaloric module while one of the first and second electrocaloric modules is energized, and a second mode where the heat transfer fluid is directed to the second electrocaloric module and from the second electrocaloric module to the heat exchanger to the first electrocaloric module, while the other of the first and second electrocaloric modules is energized. The modes are repeatedly cycled in alternating order directing the heat transfer fluid to cause a temperature gradient in each of the first and second electrocaloric modules, and fluid from a flow path between the electrocaloric modules is mixed with circulating fluid from a conditioned space to cool or heat the conditioned space.

BACKGROUND

A wide variety of technologies exist for cooling applications, including but not limited to evaporative cooling, convective cooling, or solid state cooling such as electrothermic cooling. One of the most prevalent technologies in use for residential and commercial refrigeration and air conditioning is the vapor compression refrigerant heat transfer loop. These loops typically circulate a refrigerant having appropriate thermodynamic properties through a loop that comprises a compressor, a heat rejection heat exchanger (i.e., heat exchanger condenser), an expansion device and a heat absorption heat exchanger (i.e., heat exchanger evaporator). Vapor compression refrigerant loops effectively provide cooling and refrigeration in a variety of settings, and in some situations can be run in reverse as a heat pump. However, many of the refrigerants can present environmental hazards such as ozone depleting potential (ODP) or global warming potential (GWP), or can be toxic or flammable. Additionally, vapor compression refrigerant loops can be impractical or disadvantageous in environments lacking a ready source of power sufficient to drive the mechanical compressor in the refrigerant loop. For example, in an electric vehicle, the power demand of an air conditioning compressor can result in a significantly shortened vehicle battery life or driving range. Similarly, the weight and power requirements of the compressor can be problematic in various portable cooling applications.

Accordingly, there has been interest in developing cooling technologies as alternatives to vapor compression refrigerant loops. Various technologies have been proposed such as field-active heat or electric current-responsive heat transfer systems relying on materials such as electrocaloric materials, magnetocaloric materials, or thermoelectric materials. However, many proposals have been configured as bench-scale demonstrations with limited practical applications.

BRIEF DESCRIPTION

According to some embodiments of this disclosure, an electrocaloric heat transfer system comprises first and second electrocaloric modules. The first electrocaloric module comprises a first electrocaloric element disposed between electrodes, a first port, a second port, and a first fluid flow path between the first port and the second port in thermal communication with the first electrocaloric element. The second electrocaloric module comprises a second electrocaloric element disposed between electrodes, a third port, a fourth port, and a second fluid flow path between the third port and the fourth port in thermal communication with the second electrocaloric element. The system also includes an inlet in fluid communication with and configured to receive fluid from a heat source or heat sink, and in controllable fluid communication with and configured to direct the fluid to the first port or the fourth port. An outlet is disposed in controllable fluid communication with and configured to receive fluid from the first port or the fourth port, and in fluid communication with and configured to discharge the fluid to the heat source or heat sink. A third fluid flow path is disposed between the second port and the third port. The third fluid flow path comprises a fluid mixer comprising fluid inlets in controllable communication with the second port, the third port, and a conditioned fluid space, and a fluid separator comprising a fluid inlet that receives mixed fluid from the fluid mixer, a fluid outlet in communication with the second or third port, and a fluid outlet in communication with the conditioned fluid space.

In any one or combination of the foregoing embodiments, in an operational state the fluid inlet is in communication with and receives fluid from a heat sink, and the third fluid flow path absorbs heat from the conditioned space.

In any one or combination of the foregoing embodiments, in an operational state the fluid inlet is in communication with and receives fluid from a heat source, and the third fluid flow path rejects heat to the conditioned space.

In any one or combination of the foregoing embodiments, in an operational state each of the first and second electrocaloric modules has a thermal gradient along each of the first and second flow paths, respectively.

In any one or combination of the foregoing embodiments, in an operational state the first electrocaloric module includes a hot side proximate to the first port and a cold side proximate to the second port, and the second electrocaloric module includes a hot side proximate to the fourth port and a cold side proximate to the third port.

In any one or combination of the foregoing embodiments, the fluid mixer inlet in communication with the conditioned space is configured to provide a mass flow rate of fluid at a conditioned space return temperature, and the fluid inlet in communication with the heat source or heat sink and the first and second electrocaloric modules are configured to provide a mass flow rate of fluid at an outlet temperature of the third or fourth port, such that the mixed fluid on the third fluid flow path is at a target temperature.

In any one or combination of the foregoing embodiments, the system further comprises a controller configured to alternately energize and de-energize the electrodes of the first and second electrocaloric modules while providing cycled back and forth fluid flow along the first and second fluid flow paths by alternately directing fluid from the fluid inlet to the first port to the second port to the third port to the fourth port to the fluid outlet, or from the fluid inlet to the fourth port to the third port to the second port to the first port to the fluid outlet.

In any one or combination of the foregoing embodiments, the electrodes of the first electrocaloric module are energized when the fluid is directed from the inlet to the fourth port, and the electrodes of the second electrocaloric module are energized when the fluid is directed from the inlet to the first port.

In any one or combination of the foregoing embodiments, the controller is configured to provide the cycled back and forth fluid flow along the first and second flow paths such that each back or forth fluid flow cycle displaces a volume of fluid smaller than the volume of either the first or second flow paths.

In any one or combination of the foregoing embodiments, the fluid comprises a gas.

In any one or combination of the foregoing embodiments, the fluid comprises air.

In any one or combination of the foregoing embodiments, the system further comprises a re-directable airflow path from a heat source or heat sink airflow source to the first or fourth port.

In any one or combination of the foregoing embodiments, the system further comprises a re-directable airflow path to the second or third port from the fluid separator outlet in communication with the second or third port.

In any one or combination of the foregoing embodiments, the system further comprises one or more additional electrocaloric modules individually comprising a pair of ports in controllable fluid communication with either the third fluid flow path or the fluid inlet and fluid outlet.

In any one or combination of the foregoing embodiments, the first, second, and additional electrocaloric modules are configured as a cascade, and the system further comprises fluid flow shut-offs between each electrocaloric module in the cascade.

In any one or combination of the foregoing embodiments, the one or more additional caloric modules are each configured with a flow path between the pair of ports that is parallel to the first or second flow paths.

In some embodiments, an electrocaloric heat transfer system comprises a first electrocaloric module comprising a first electrocaloric element disposed between electrodes, a first port, a second port, and a first fluid flow path between the first port and the second port in thermal communication with the first electrocaloric element. A fluid innet is configured to receive fluid from a heat source or heat sink, and to controllably direct the fluid to the first port. A fluid outlet is configured to controllably receive fluid from the first port, and to discharge the fluid to the heat source or heat sink. A third fluid flow path comprises a fluid mixer comprising fluid inlets in controllable communication with the second port and with a conditioned fluid space, and a fluid separator comprising a fluid inlet that receives mixed fluid from the fluid mixer, a fluid outlet in communication with the second port, and a fluid outlet in communication with the conditioned fluid space. In some embodiments, the system further comprises a controller configured to alternately energize and de-energize the electrodes of the first and second electrocaloric modules while providing cycled back and forth fluid flow along the first and second fluid flow paths by alternately directing fluid from the fluid inlet to the first port to the second port to the fluid mixer, or from the fluid separator to the second port to the first port to the fluid outlet. In some embodiments, the controller is further configured to: (i) the electrodes of the first electrocaloric module are energized when fluid is directed from the separator to the second port, and the electrodes of the first electrocaloric module are not energized when the fluid is directed from the inlet to the first port, or (ii) provide the cycled back and forth fluid flow along the first flow path such that each back or forth fluid flow cycle displaces a volume of fluid smaller than the volume of the first path; or (iii) both (i) and (ii).

In some embodiments, a method of transferring heat comprises

(a) directing a heat transfer fluid to a first electrocaloric module and from the first electrocaloric module to a heat exchanger to a second electrocaloric module while energizing one of the first and second electrocaloric modules;

(b) directing the heat transfer fluid to the second electrocaloric module to the heat exchanger to the first electrocaloric module while energizing the other of the first and second electrocaloric modules;

(c) repeating (a) and (b) in alternating order to cause a temperature gradient in each of the first and second electrocaloric modules; and

(d) mixing outlet fluid flow from the third or fourth port with fluid from a conditioned space, directing a portion of the mixed fluid flow to the conditioned space, and receiving a portion of the mixed fluid flow as inlet flow at the third or fourth port, and rejecting heat to the fluid from the heat exchanger or absorbing heat from the fluid by the heat exchanger.

In any one or combination of the foregoing method embodiments, the second electrocaloric module is energized in (a) and the first electrocaloric module is energized in (b), and heat is absorbed from the conditioned space.

In any one or combination of the foregoing method embodiments, the first electrocaloric module is energized in (a) and the second electrocaloric module is energized in (b), and heat is transferred to the conditioned space.

In any one or combination of the foregoing method embodiments, an amount of fluid of smaller volume than the fluid volume of either the first and second electrocaloric modules is introduced during each of (a) and (b).

In any one or combination of the foregoing method embodiments, the relative relative mass flow rates of the third fluid flow path compared to the conditioned space fluid flow rates are controlled.

DETAILED DESCRIPTION

With reference now to the Figures,FIG. 1schematically depicts an example embodiment of a heat transfer system10. As shown inFIG. 1, the heat transfer system10comprises a first electrocaloric module12and a second electrocaloric module14. Each of the first and second electrocaloric modules12,14includes a stack of electrocaloric elements (not shown), e.g., electrocaloric films disposed between electrodes disposed between electrodes. Examples of electrocaloric materials for the electrocaloric film can include but are not limited to inorganic materials (e.g., ceramics), electrocaloric polymers, and polymer/ceramic composites. Examples of inorganics include but are not limited to PbTiO3(“PT”), Pb(Mg1/3Nb2/3)O3(“PMN”), PMN-PT, LiTaO3, barium strontium titanate (BST) or PZT (lead, zirconium, titanium, oxygen). Examples of electrocaloric polymers include, but are not limited to ferroelectric polymers (e.g., Polyvinylidene fluoride and copolymers containing repeat units derived from vinylidene fluoride and other halogenated or non-halogenated addition polymerizable comonomers), liquid crystal polymers, and liquid crystal elastomers.

With continued reference toFIG. 1, the first electrocaloric module12includes a first port18and a plurality of second ports20, with a first fluid flow path21between the first and second ports and in thermal communication with the electrocaloric modules12of the first electrocaloric module12. The second electrocaloric module14includes a plurality of third ports22and a fourth port24, with a second fluid flow path25between the third and fourth ports and in thermal communication with the electrocaloric modules12of the second electrocaloric module14. An inlet26receives a fluid28from a heat source or heat sink (not shown). Examples of fluids for working fluid28include but are not limited to air (including modified air such as oxygen-enriched air (OEA), nitrogen-enriched air (NEA)), other gases (e.g., virtually any industrial process gas), polar or non-polar organic liquids (including dielectric or conductive organic liquids), fuels, electroactive fluids, water, and many other specific examples. Electrically-conductive fluids, including but not limited to inherently conductive fluid compounds or fluids comprising an electrolyte that promotes conductivity (e.g., water comprising a dissolved salt), can utilize appropriate device design configuration to avoid short circuits through the fluid. Example embodiments of a device design to avoid such short circuits is to embed the electrodes within an electrocaloric film or between adjacent electric films to isolate the electrode from the electrically conductive fluid, as disclosed in patent application PCT/US2015/67185, the disclosure of which is incorporated herein by reference in its entirety. Example embodiments of a electrocaloric devices and systems utilizing electroactive liquids are disclosed in patent application PCT/US2014/068497, the disclosure of which is incorporated herein by reference in its entirety. Air inlet26can also include a fan to promote flow of the fluid28from the heat source or heat sink to the electrocaloric modules. The heat source or heat sink can be a source of fluid at a suitable heat sink/source temperature and having a relatively large thermal mass (e.g., outside ambient air or a large mass of liquid at a suitable temperature), or can be a heat exchanger in thermal communication with a thermal target, such that the heat transfer system sees it as a heat sink or heat source. The fluid28is controllably directed by flapper doors30and31from the inlet26to the first electrocaloric module12through the first port18or to the second electrocaloric module14through the fourth port24. Flapper doors30and31can be set in the position designated as30aand31ato direct fluid28from the inlet26to the first electrocaloric module12, or they can be set in the position designated as30b,31bto direct fluid28from the inlet26to the second electrocaloric module14.

Fluid entering through the inlet26displaces fluid in the first or second module12,14onto a third fluid flow path32between the third and fourth ports22and24. As will be discussed further below, flow can be in either direction on the first and second fluid flow paths21and25(as indicated by the bi-directional arrows), depending on the position of the flapper doors. Fluid displaced from the third fluid flow path32is directed into the other of the first or second electrocaloric modules12,14(the module not receiving fluid from the inlet26) by flapper doors33and35, from where it exits as working fluid discharge28′ through the first or second port18,20and flows to the heat source or heat sink. Flapper doors33and35can be set in the position designated as33aand35ato direct fluid from port20to the fluid mixer34, or they can be set in the position designated as33b,35bto direct fluid from the port22to the second fluid mixer34along an alternate route32′ for the third fluid flow path. Third fluid flow path alternate route32′ flows into the fluid mixer34; however that flow path connection is omitted in the Figures for ease of illustration.

Fluid on the third fluid flow path32flows to fluid mixer34having inlets in fluid communication with the third fluid flow path32and return fluid flow36from a conditioned fluid space (not shown). The mixed fluid from the fluid mixer34is separated by fluid separator38, which directs a portion of the fluid back to the conditioned space as conditioned fluid40(assisted by fan41) and directs a portion along a continuation of fluid flow path32(designated as32″). Although schematically depicted as separate components, the fluid mixer34and the separator36can be integrated into a single unit or device. The fluid continuing along the portion of the third fluid flow path32″, assisted by fan42is directed by the flapper doors33,35to either of the ports20or18, with flow directed to port22with the flapper doors in position33a,35a, or to port20with the doors in position33b,35b.

In operation, the system operates the first and second electrocaloric modules12,14out of sync in an internal heat regenerative mode, as described in more detail below. In this mode, one of the electrocaloric modules operates in a regeneration mode absorbing heat from the working fluid with the electrodes de-energized, while the other electrocaloric module operates in an active mode transferring heat to the working fluid with the electrodes energized. The system is operated such that each of the electrocaloric modules alternately shifts between regeneration mode and active mode, with synchronization of the fluid flow. Fluid flow is synchronized with the operational states to provide a back and forth flow pattern along the first, second, and third fluid flow paths so that each of the first and second modules provides a regeneration-enhanced temperature lift.

A non-limiting example embodiment of the operation of the system in a cooling mode is described below with respect toFIGS. 2A and 2B. Example fluid temperatures suitable for an HVAC heat transfer application (e.g., residential or commercial cooling) at ambient temperate conditions are referenced below to assist in understanding of the operation of the system, however, it should be understood that these temperatures are used for illustrative purposes only and other temperatures can be utilized depending on system design parameters and target application. Reference numerals fromFIG. 1are carried forward intoFIGS. 2A and 2Band have the same meaning as inFIG. 1, so their description is not repeated below.

As shown inFIG. 2A, the system can operate in a first mode where fluid28(e.g., outside air) enters the inlet from a heat sink. The air is directed by the flapper doors30,31in positions30a,31ato port18of the first electrocaloric module12which is in regenerative mode with the electrodes de-energized. As an illustrative example, the temperature of the outside air can be at about 82° F. and can flow at a relative mass flow rate of 4 {dot over (m)}. In regenerative mode with the electrodes de-energized, the electrocaloric material experiences an increase in entropy compared to a prior active mode state, and a concomitant drop in temperature (assuming adiabatic conditions). Heat is transferred from the relatively warm air along the first fluid flow path21to the relatively cold electrocaloric elements, resulting in a drop in temperature of the air from about 82° F. at the port18to about 55° F. at the port20. The air is directed from the port20by the doors33,35in the33a,35aposition along the third fluid flow path32to fluid mixer34, where it is mixed with conditioned space return flow36(in this example, at 80° F. and a mass flow rate of 1 {dot over (m)}), resulting in a mixed air flow exiting the fluid mixer34at about 60° F. and 5 {dot over (m)} flow rate. 1 {dot over (m)} of this flow 60° F. air is returned by the separator36to the conditioned space as conditioned air, and 4 {dot over (m)} of the flow of 60° F. air is directed to the fan42, where doors33,35in the33a,35aposition direct the air to port22where it enters the second electrocaloric module14. In this first operational mode, the second electrocaloric module14is in active mode with the electrodes energized. In active mode with the electrodes energized, the electrocaloric material experiences a decrease in entropy compared to a prior regenerative mode state, and a concomitant increase in temperature (assuming adiabatic conditions). Heat is transferred from the relatively warm electrocaloric elements to the relatively cold air along the second fluid flow path25, resulting in an increase in temperature of the air from about 60° F. at the port22to about 88° F. at the port24. This removal of heat from the electrocaloric elements prepares the electrocaloric elements for the next regenerative cycle where removal of the electric field results in a temperature drop (assuming adiabatic conditions) for the electrocaloric material.

As shown inFIG. 2B, the system can operate in a second mode where outside air is directed by the flapper doors30,31in positions30b,31bto port24of the second electrocaloric module14which is in regenerative mode with the electrodes de-energized. As an illustrative example, the temperature of the outside air can be at about 82° F. and can flow at a relative mass flow rate of 4 {dot over (m)}. In regenerative mode with the electrodes de-energized, the electrocaloric material experiences an increase in entropy compared to a prior active mode state, and a concomitant drop in temperature (assuming adiabatic conditions). Heat is transferred from the relatively warm air along the second fluid flow path25to the relatively cold electrocaloric elements, resulting in a drop in temperature of the air from about 82° F. at the port24to about 55° F. at the port22. The air is directed from the port22by the doors33,35in the33b,35bposition along the fluid flow path alternate route32′ to fluid mixer34(connection not shown), where it is mixed with conditioned space return flow36(in this example, at 80° F. and a mass flow rate of 1 {dot over (m)}), resulting in a mixed air flow exiting the fluid mixer34at about 60° F. and 5 {dot over (m)} flow rate. 1 {dot over (m)} of this flow 60° F. air is returned by the separator38to the conditioned space as conditioned air, and 4 {dot over (m)} of the flow of 60° F. air is directed to the fan42, where doors33,35in the33b,35bposition direct the air to port20where it enters the first electrocaloric module12. In this second operational mode, the first electrocaloric module12is in active mode with the electrodes energized. In active mode with the electrodes energized, the electrocaloric material experiences a decrease in entropy compared to a prior regenerative mode state, and a concomitant increase in temperature (assuming adiabatic conditions). Heat is transferred from the relatively warm electrocaloric elements to the relatively cold air along the first fluid flow path21, resulting in an increase in temperature of the air from about 60° F. at the port20to about 88° F. at the port18. This removal of heat from the electrocaloric elements prepares the electrocaloric elements for the next regenerative cycle where removal of the electric field results in a temperature drop (assuming adiabatic conditions) for the electrocaloric material.

As mentioned above, the embodiments depicted inFIGS. 1-4are example embodiments, and other configurations can be utilized. For example, each of theFIGS. 1-3depicts two electrocaloric modules12and14, andFIGS. 4A and 4Bas discussed below depict a cascaded of electrocaloric modules. however, alternative configurations toFIGS. 1-3can utilize multiple electrocaloric modules in parallel with either or both of the first and second elements12and14, in common fluid communication with the inlet, outlet, heat sink/source, and third fluid flow path through flow collection and distribution structures (not shown) such as manifolds, headers or plenums. Also, multiple systems can also be networked together. For example, a plurality of systems10could be disposed at varying locations along a building-wide air ventilation circulation loop, all in communication with the same thermal target. The networked systems, each with its own third fluid flow path that intermixes and is separated from the wider circulation loop, could have separate working fluid flow paths to and from the heat sink/source or they could share a common flow path in parallel through flow control devices (e.g., manifolds, headers, plenums) as described above.

The system10can be operated in either cooling mode as described above, or in a heating or heat pump mode. In both modes, the electrocaloric modules are alternately cycled out of sync between an active mode where the electrodes are energized and a regeneration mode where the electrodes are de-energized. In the cooling mode, the first electrocaloric module12has a hot side proximate to port18and a cold side proximate to ports20, and the second electrocaloric module14has a hot side proximate to port24and a cold side proximate to ports22. In the cooling mode, the fluid28is directed from a heat sink to the electrocaloric module in regeneration mode, with flow proceeding from the regenerating electrocaloric module to the third fluid flow path32where it is mixed with return fluid from a conditioned space to provide cooled conditioned supply air for the conditioned space. In the heat pump mode, the first electrocaloric module12has a cold side proximate to port18and a hot side proximate to ports20, and the second electrocaloric module14has a cold side proximate to port24and a hot side proximate to ports22. In the heat pump mode, the fluid28is directed from a heat source to the electrocaloric module in active mode, with flow proceeding from the active electrocaloric module to the third fluid flow path32where it is mixed with return fluid from a conditioned space to provide heated conditioned supply air for the conditioned space.

In some embodiments, the electrocaloric modules12,14are operated in an internal regenerative mode. In an internal regenerative mode, only a portion of the total volume of working fluid in each of the respective first and second flow paths21,25is displaced during each cycle of the alternating cycles of activation and regeneration. This allows heat from the activation cycles retained by fluid internal to the first or second flow path that was not displaced during the active cycle to provide heat to the electrocaloric material during the regenerative cycle. With repetition of cycles where each electrocaloric module experiences a back and forth partial displacement of fluid for each active/regenerative cycle, such internal regeneration can provide a significant temperature gradient (i.e., temperature lift) across the electrocaloric modules between18and20, and between ports24and22. In some embodiments, the system can be configured to provide a target temperature at the ports22,24, in order to provide a target temperature to meet the thermal load of the conditioned space on the third fluid flow path. System control to achieve a target temperature at the ports22,24and/or a target temperature for the conditioned air40can be implemented in various ways. For example, in some embodiments, target temperatures and/or target levels of heat transfer can be achieved by controlling the relative mass flow rates of the third fluid flow path compared to the fluid flow rates for return flow36and conditioned fluid flow40through the mixer34and separator38.

In some embodiments, the heat transfer system can include one or more additional electrocaloric modules in a cascaded configuration. An example embodiment of a cascaded heat transfer system100is schematically depicted inFIGS. 3, 4A, and 4B. As shown inFIGS. 3, 4A, and, and4B, cascaded electrocaloric modules44,46,48, and52share a common third fluid flow path32, and a common flow path45for heat sink/source fluid (e.g., outside air). Fluid flow shut-offs54,56,58, and60are disposed along the flow path45between the electrocaloric modules, and fluid flow shut-offs62,64,66, and68are disposed along the common third fluid flow path32between the electrocaloric modules. As will be appreciated from an understanding of the operation of this system (described below), any two adjacent electrocaloric modules can be characterized and related to one another with first and fourth ports in controllable communication with the common flow path45for heat sink/source fluid flow and second and third ports in controllable communication with the common third fluid flow path32. Other features numbered the same as inFIGS. 1, 2A, and 2Bare the same as described with respect to those figures, which description is not repeated hereinbelow.

During operation, as shown inFIG. 4A, the system can operate in a first mode where fluid28(e.g., outside air) enters the inlet from a heat sink. In the first mode of operation, fluid flow shut-offs54,58,64, and68are closed, and fluid flow shut-offs56,60,62, and66are open. For cooling, in this first mode of operation, electrocaloric modules44,48, and52are in regenerative mode with the electrodes de-energized. As an illustrative example, the temperature of the outside air can be at about 82° F. and can flow at a relative mass flow rate of 4 {dot over (m)}. In regenerative mode with the electrodes de-energized, the electrocaloric material experiences an increase in entropy compared to a prior active mode state, and a concomitant drop in temperature (assuming adiabatic conditions). Heat is transferred from the relatively warm air to the relatively cold electrocaloric elements, resulting in a drop in temperature of the air at the inflowing port of each regenerating electrocaloric module to the air at the outflowing port of each regenerating electrocaloric module. Meanwhile, in this mode of operation, air is directed from the relatively cool common third fluid flow path32to the activated electrocaloric modules46and50to prepare them for the next regenerative cycle.

As shown inFIG. 4B, the system can operate in a second mode where fluid flow shut-offs56,60,62, and66are closed, fluid flow shut-offs54,58,64, and68are open, electrocaloric modules46and50are in regenerative mode with the electrodes de-energized, and electrocaloric modules44,48, and52are activated with the electrodes energized. As can be seen by a comparison ofFIGS. 4A and 4B, each electricaloric module undergoes internal regeneration with a back and forth fluid flow between a hot side and a cold side while continuous fluid flow is maintained along the flow paths32and45to allow for efficient operation of fluid prime movers such as fans. The cascaded configuration of the electrocaloric module can allows for additive temperature lifts among the electrocaloric modules to be achieved.

The air is directed along the third fluid flow path32to fluid mixer/separator70where it is mixed with conditioned space return flow36from conditioned space72(in this example, at 80° F. and a mass flow rate of 1 {dot over (m)}), resulting in a mixed air flow exiting the fluid mixer/separator70at about 60° F. and 5 {dot over (m)} flow rate. 1 {dot over (m)} of this flow 60° F. air is returned by the separator36to the conditioned space72as conditioned air40, and 4 {dot over (m)} of the flow of 60° F. air is directed back to the electrocaloric modules.

Alternatively to the systems described above, in some embodiments, a system can include a single electrocaloric module as schematically depicted inFIG. 5. The numbering of components and their function is repeated fromFIG. 1, the specifics of which do not necessitate repetition and can be referenced from the description ofFIG. 1above. The system ofFIG. 5provides alternating back and forth flow of the fluid28between the electrocaloric module12and the heat source or heat sink (not shown), which is treated in the electrocaloric module12and mixed with and separated from fluid from the thermal target in mixer34and separator38. The fluid on fluid flow path32is then returned to the electrocaloric module12flowing in the opposite direction toward the heat source or heat sink. Timing and sequencing of the bi-directional fluid flow along the flow path can be accomplished by timing and sequencing of the inlet and outlet flows of the mixer and separator34,38.