Air conditioning system with vapor bypassing

Abstract

An air conditioning system that includes an evaporator stage, first and second sorption stages that transition between active states and regeneration states, a compressor stage that receives a portion of a refrigerant vapor from the first or second sorption stage in the active state, a condenser stage that receives the refrigerant vapors from the compressor and from the first or second sorption stage in the regeneration state in a manner that bypasses the compressor stage, and where condenser stage also condenses the received refrigerant vapors and directs the refrigerant condensate to the evaporator stage.

Description

CROSS-REFERENCE TO RELATED APPLICATION(S)

The present application is based on and claims the benefit of U.S. provisional patent application Ser. No. 62/056,750, filed Sep. 29, 2014, the content of which is hereby incorporated by reference in its entirety.

STATEMENT OF GOVERNMENT INTEREST

This invention was made with government support under SBIR Grant IIP No. 1345387, awarded by the National Science Foundation. The government has certain rights in the invention.

BACKGROUND

The present disclosure is directed to an air conditioning system and method of use thereof. In particular, the present disclosure is directed to air conditioning system that incorporates both vapor sorption and compression stages.

Air conditioners are provided in a variety of sizes to modify air characteristics, such as temperature and humidity, to achieve more comfortable conditions. Conventional air conditioners operate under evaporation and condensation processes, where a refrigerant is evaporated to absorb heat (for cooling indoor air) and then compressed and cooled to condense back to a liquid again. This process is repeated in continuous cycle while the air conditioner operates.

SUMMARY

The present disclosure is directed to an air conditioning system that includes an evaporator stage configured to remove heat from a medium to be cooled by evaporation of a refrigerant condensate (and producing a refrigerant vapor), and first and second sorption stages configured to interchangeably transition between active states and regeneration states, where the first and second sorption stages each comprises a sorption column configured to trap a first portion of the refrigerant vapor received while in the active state. The air conditioning system also includes a compressor stage configured to receive a second portion of the refrigerant vapor from the first or second sorption stage in the active state, and a condenser stage configured to receive the refrigerant vapor from the compressor and to receive the refrigerant vapor from the first or second sorption stage in the regeneration state in a manner that bypasses the compressor stage, where the condenser stage is also configured to condense the received refrigerant vapors as a refrigerant condensate. The air conditioning system further includes a condensate line configured to direct a flow of the refrigerant condensate from the condenser stage to the evaporator stage.

Another aspect of the present disclosure is directed to an air conditioning system that includes an evaporator stage configured to produce a refrigerant vapor, a first sorption stage having a first sorption column, and a second sorption stage having a second sorption column. The first and second sorption stages are configured to be interchangeably used in an active state to trap a first portion of the refrigerant vapor received from the evaporator stage, and in a regeneration state to regenerate the first or second sorption column. The air conditioning system also includes a compressor stage configured to receive a second portion of the refrigerant vapor from the first or second sorption stage that is the active state, and a condenser stage configured to receive the refrigerant vapor from the compressor, and to receive the refrigerant vapor from the first or second sorption stage in the regeneration state, where the condenser stage is also configured to condense the received refrigerant vapors as a refrigerant condensate. The air conditioning system further includes a condensate line configured to direct a flow of the refrigerant condensate from the condenser stage to the evaporator stage.

Yet another aspect of the present disclosure is directed to a method for conditioning air. The method includes evaporating a refrigerant condensate in an evaporator stage to remove heat from a cooling medium (and to produce a refrigerant vapor), trapping a first portion of the refrigerant vapor in a first sorption column, and passing a second portion of the refrigerant vapor through the first sorption column to a compressor stage. The method also includes pressurizing the second portion of the refrigerant vapor in the compressor stage, and forcing the pressurized portion of the refrigerant vapor into a condenser stage, and driving additional refrigerant vapor from a second sorption column to the condenser stage in a manner that bypasses the compressor stage. The method further includes condensing the pressurized portion of the refrigerant vapor and the additional refrigerant vapor in the compressor stage to produce the refrigerant condensate, and passing the refrigerant condensate from the compressor stage to the evaporator stage.

DEFINITIONS

Unless otherwise specified, the following terms as used herein have the meanings provided below:

The terms “command”, “commanding”, and the like, with reference to a controller commanding a device (e.g., a valve, an actuator, a compressor, and the like), refers to the direct and/or indirect relaying of control signals from the controller to the device such that the device operates in conformance with the relayed signals. The signals may be relayed in any suitable form, such as communication signals to a microprocessor on the device, applied electrical power to operate the device, and the like.

The terms “preferred” and “preferably” refer to embodiments of the invention that may afford certain benefits, under certain circumstances. However, other embodiments may also be preferred, under the same or other circumstances. Furthermore, the recitation of one or more preferred embodiments does not imply that other embodiments are not useful, and is not intended to exclude other embodiments from the scope of the present disclosure.

The term “providing”, such as for “providing a material”, when recited in the claims, is not intended to require any particular delivery or receipt of the provided item. Rather, the term “providing” is merely used to recite items that will be referred to in subsequent elements of the claim(s), for purposes of clarity and ease of readability.

The terms “at least one” and “one or more of” an element are used interchangeably, and have the same meaning that includes a single element and a plurality of the elements, and may also be represented by the suffix “(s)” at the end of the element.

The terms “about” and “substantially” are used herein with respect to measurable values and ranges due to expected variations known to those skilled in the art (e g, limitations and variabilities in measurements).

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic illustration of an air conditioning system of the present disclosure in use with an environment to be conditioned (e.g., an indoor location).

FIG. 2 is a schematic illustration of an example evaporation/condensation unit of the air conditioning system.

FIGS. 3 and 4 are schematic illustrations of the evaporation/condensation unit as shown in FIG. 2, illustrating an example operation of the unit.

DETAILED DESCRIPTION

The present disclosure is directed to an air conditioning system that utilizes both a compressor and one or more sorption columns to generate conditioned air having a reduced temperature and/or humidity. As discussed below, the sorption column(s) can reduce vapor flow rate directed to the compressor with the use of a desiccant regeneration or sorption step, thereby preferably allowing the compressor to be smaller in size and require a lower power consumption.

FIG. 1 illustrates an example air conditioning (AC) system 10 of the present disclosure, which is set up to condition the air in an environment 12. The environment 12 may be any suitable enclosable environment, such as a residential home, commercial building, industrial building, and the like, where the AC system 10 preferably has throughput capabilities that are capable of conditioning the volume of the environment 12.

In the shown embodiment, the AC system 10 includes unit 14, a cooling fluid source 16, and a heat source 18. The system 10 may alternatively include multiple units 14, multiple cooling fluid sources 16, and/or multiple heat sources 18. The cooling fluid source 16 is a source or reservoir of a “cooling fluid” (e.g., cooling water or ambient/cool air), and is connected to the unit 14 with a pair of cold inlet lines 20 (individually referred to as cold inlet lines 20a and 20b) and an outlet line 22. In some embodiments, the cooling fluid source 16 may be a cold water plumbing line that directs a pressurized flow of cooling water through the cold inlet lines 20 into unit 14, where it exits unit 14 through the cold outlet line 22, such as into a drain. Alternatively, the cooling fluid source 16 may include a reservoir of the cooling fluid, and optionally, one or more pumps (not shown) to generate the circulation pressure.

The heat source 18 is a source of thermal energy, and may optionally be external to the AC system 10, such as a source of waste heat from an industrial process, solar heat, heat from an internal combustion engine, and the like. The heat source 18 is connected to the unit 14 with a pair of hot inlet lines 24 (individually referred to as hot inlet lines 24a and 24b) and a pair of hot outlet lines 26 (individually referred to as hot outlet lines 26a and 26b). In the shown example, the heat source 18 may include one or more heat exchangers 28 or other suitable heat transfer devices, which may be connected to the hot inlet lines 24 and hot outlet lines 26, allowing a “heating fluid” to circulate between the unit 14 and the heat source 18. The heating fluid may be any suitable heated fluid, such as heated pressurized water, steam, heated air and the like. The heat source 18, hot inlet lines 24, and/or hot outlet lines 26 may optionally include one or more pumps (not shown) to circulate the heating fluid.

The terms “cold” and “hot”, with reference to the fluid lines of the AC system 10 are used to distinguish the cooling and heating fluids relative to each other, where the cooling fluids through the “cold” lines are used for cooling purposes in the unit 14, and the heating fluids through the “hot” lines are used for desiccant regeneration purposes in the unit 14. The terms “cold” and “hot”, are used with reference to the fluid lines of AC system 10, and are not otherwise intended to limit the fluids to any particular temperatures.

As further shown in FIG. 1, the unit 14 may connect to the environment 12 with an inlet fluid line 30 and outlet fluid line 32. In the shown example, the environment 12 may include one or more heat exchangers 34 or other suitable heat transfer devices, which may be connected to the inlet fluid line 30 and the outlet fluid line 32. This allows a “chilled fluid” to circulate between the environment 12 and the unit 14, where the chilled fluid may be any suitable fluid, such as cold water or air from the environment 12. The environment 12 also preferably includes an air blower (not shown), such as part of a central air system, to circulate the air cooled by the heat exchanger 34.

The unit 14, the inlet fluid line 30, and/or outlet fluid line 32 may also optionally include one or more pumps (not shown) to circulate the chilled fluid. The environment 12 may also include one or more blowers or other air circulating devices (not shown) to circulate air across the heat exchanger(s) 34, thereby conditioning the air. In some alternative embodiments, such as where the unit 14 resides in or adjacent to the environment 12 (e.g., a window-sized unit), the inlet fluid line 30 and the outlet fluid line 32 may be omitted. In this embodiment, the unit 14 may retain an air blower (not shown) to circulate the cooled air in the environment 12. Accordingly, in some embodiments, the AC system 10 may be part of a central air system of the environment 12.

The AC system 10 may also include a controller 36, which is configured to operate the various components of the AC system 10 (e.g., of unit 14) with the use of one or more communication lines 36a, and may be internal and/or external to the unit 14. The controller 36 may include a variety of components that are contained in conventional process circuits, computers, servers, media devices, signal processing devices, and the like, such as optionally one or more user interfaces, memory controllers, processors, storage media, input/output (I/O) controllers, communication adapters, related processing circuitry (e.g., digital and analog components), and the like. The controller 36 may also optionally communicate with one or both of the heat exchangers 28 and 34 to regulate the operation of the unit 14 (e.g., with one or more thermostat devices).

As shown in FIG. 2, the unit 14 is dual-column air conditioning unit that utilizes both a compressor and one or more sorption columns to generate conditioned air in the environment 12 having a reduced temperature and/or humidity. The dual column refers to a pair of sorption columns 38 and 40, which may be interchangeably and selectively used, where the sorption column 38 may be used to assist in the air conditioning process while the sorption column 40 is being regenerated (and vice versa).

The sorption columns 38 and 40 may each retain a bed of one or more desiccants that adsorb (and/or absorb) a refrigerant vapor (e.g., water vapor) during the air conditioning process. Examples of suitable desiccants for use in each of the sorption columns 38 and 40 include silica-based media, such as silica gels and/or porous aluminosilicate minerals (e.g., zeolites). Examples of suitable zeolites for use in the sorption columns 38 and 40 include hydrated and anhydrous structures of aluminosilicate minerals, which may contain one or more of sodium (Na), potassium (K), cerium (Ce), calcium (Ca), barium (Ba), strontium (Sr), lithium (Li), and magnesium (Mg).

For smaller-scale units 14 (e.g., for residential uses), the sorption columns 38 and 40 may each include smaller amounts of the desiccant, such as from about 0.5 kilograms to about 5 kilograms, or from about 1 kilogram to about 3 kilograms of desiccant. Alternatively, for larger-scale units 14 (e.g., for industrial uses), sorption columns 38 and 40 may each include a larger amount of desiccant, such as from about 500 kilograms to about 5,000 kilograms, or from about 1,000 kilogram to about 3,000 kilograms of desiccant. Accordingly, the AC system 10 and the unit 14 may be sized to accommodate the environments 12 having a variety of different dimensions and conditions (e.g., different cooling requirements).

As further shown in FIG. 2, a cold inlet line 24a and hot inlet line 26a may meet at an inlet valve 42 on the left side of the unit 14, and the cold inlet line 24b and hot inlet line 26b may meet at the inlet valve 44 on the right side of the unit 14. Directional orientations, such as left, right, and the like are merely used for ease of discussion, and are not intended to limit the unit 14 to any particular orientation.

Inlet valves 42 and 44 are actuating fluid valves that are preferably operated by the controller 36. For instance, the controller 36 may command the inlet valve 42 to selectively switch the inlet flow between the cold inlet line 24a and the hot inlet line 26a, and may command the inlet valve 44 to switch the inlet flow between the cold inlet line 24b and hot inlet line 26b.

The inlet valve 42 directs the received inlet flow through the inlet fluid line 46 to the heat exchanger 48 located within the desiccant bed of the sorption column 38. The heat exchanger 48 correspondingly directs the flow through an outlet fluid line 50 to an outlet valve 52. The outlet valve 52 may selectively connect the outlet fluid line 50 to the hot outlet line 26a or circulation line 54, where the circulation line 54 may terminate at a manifold 56.

Similarly, the inlet valve 44 directs the received inlet flow through inlet fluid line 58 to a heat exchanger 60 located within the desiccant bed of the sorption column 40. The heat exchanger 60 correspondingly directs the flow through an outlet fluid line 62 to an outlet valve 64. The outlet valve 64 may selectively connect the outlet fluid line 62 to the hot outlet line 26b or a circulation line 66, where the circulation line 66 may terminate at the manifold 56.

The outlet valves 52 and 64 are additional actuating fluid valves that are also preferably operated by the controller 36. The manifold 56 is a fluid manifold that directs the received flows from the circulation lines 54 and 66 through a fluid line 67 to condenser coils 68. The condenser coils 68 are preferably a series of connected heat transfer coils that direct the incoming flows from the manifold 56 back out to the cold outlet line 22 (and to cooling source 16 and/or a drain). In some embodiments, the manifold 52 may also include an actuating fluid valve operated by the controller 36 to selectively direct the flows from the circulation lines 54 and 66 to the condenser coils 68.

The unit 14 may also include a housing 70 that separates the components of the unit 14 into separate enclosable stages or compartments, referred to as an evaporator stage 72, sorption stages 74 and 76, a compressor stage 78, and a condenser stage 80. The evaporator stage 72 is the bottom-most compartment of the unit 14 and retains a heat exchanger 82. The heat exchanger 82 interconnects the inlet fluid line 30 and the outlet fluid line 32, allowing the chilled fluid to circulate through the inlet fluid line 30, the heat exchanger 82, the outlet fluid line 32, and the heat exchanger 34 (at the environment 12, shown in FIG. 1).

Alternatively, as mentioned above, in embodiments in which the unit 14 resides in or adjacent to the environment 12 (e.g., a window-sized unit), the inlet fluid line 30 and outlet fluid line 32 may be omitted. In this embodiment, the heat exchanger 82 may optionally extend out of the evaporator stage 72 and into the environment 12. In addition, the unit 14 may retain an air blower (not shown) to circulate air that is cooled by the heat exchanger 82 throughout the environment 12.

The sorption stages 74 and 76 are adjacent compartments located above the evaporator stage 72, which respectively retain the sorption columns 38 and 40. The compressor stage 78 is located in the upper region or above the sorption stages 74 and 76, and retains the compressor 84. The compressor 84 is a gas or air compressor configured to pressurize and force refrigerant vapors that enter the compressor stage 78 from either the sorption stage 74 or sorption stage 76 into the condenser stage 80. The compressor 84 may also optionally purge the unit 14 of any non-condensing gases. As discussed below, the use of the sorption columns 38 and 40 can significantly reduce the process requirements of the compressor 84, allowing the compressor 84 to be smaller in size and utilize less power.

The condenser stage 80 is the top-most compartment of the unit 14, and includes the condenser coils 68 and the condensate tank 86. As discussed below, the condenser coils 68 may cause the refrigerant vapor in the condenser stage 80 to condense and fall into the condenser tank 86 as condensate 88. The condenser tank 86 is connected to a condensate line 90 for directing flows of the condensate 88 to an expansion valve 92. The expansion valve 92 relieves pressure on the condensate 88, and directs the resulting condensate 88 through a refrigerant line 94 to evaporator nozzles 96 within the evaporator stage 72. The evaporator nozzles 96 correspondingly allow the condensate 88 to exit the refrigerant line 94 into the evaporation stage 72 for further expansion and evaporation.

As further shown, the evaporator stage 72 is respectively accessible to the sorption stages 74 and 76 through ports 98 and 100, where the ports 98 and 100 are respectively closable with actuating doors 102 and 104. The sorption stages 74 and 76 are respectively accessible to the compressor stage 78 through ports 106 and 108, where the ports 106 and 108 are respectively closable with actuating doors 110 and 112. Additionally, the sorption stages 74 and 76 are also respectively accessible to the condenser stage 80 through ports 114 and 116, where the ports 114 and 116 are respectively closable with actuating doors 118 and 120. The compressor stage 78 is correspondingly accessible to the condenser stage 80 through port 122, which is located on the opposing side of compressor 84 from the ports 106 and 108.

As can be seen, the sorption stages 74 and 76 with the sorption columns 38 and 40 may be interchangeably used during the operation of the unit 14. For example, while the sorption column 38 is in an “active state” to assist in the air conditioning process, the sorption column 40 may be in a “regeneration state”. After a set duration, the operations of the sorption columns 38 and 40 may switch such that the sorption column 40 is in the active state to assist in the air conditioning process, and the sorption column 38 may be in the regeneration state. This interchange may then proceed in a back-and-forth manner during the operation of the unit 14.

In some embodiments, the unit 14 may alternatively include three or more sorption columns and sorption stages, such that at least one sorption column is in the active state to assist in the air conditioning process while at least one other sorption column is in the regeneration state. Examples of suitable numbers of sorption columns and sorption stages for the unit 14 range from two to eight, or two to six, or two to four.

As shown in FIG. 3, during start up and operation of the AC system 10 with the sorption column 38 in the active state and the sorption column 40 in the regeneration state, the controller 36 may command the inlet valve 42 to open the flow between the cold inlet line 20a and the inlet fluid line 46, which closes off access to the hot inlet line 24a. The controller 36 may also command the outlet valve 52 to open the flow between the outlet fluid line 50 and the circulation line 54, which closes off access to the hot outlet line 26a.

Accordingly, the cooling fluid from the cooling source 16 (shown in FIG. 1) may flow under pressure through the cold inlet line 20a, inlet value 42, inlet fluid line 46, heat exchanger 48, outlet fluid line 50, outlet valve 52, circulation line 54, manifold 56, fluid line 67, condenser coils 68, cold outlet line 22, and back to the cooling source 16 and/or a drain. In comparison, the heating fluids in the hot inlet line 24a and hot outlet line 26a are closed off from the heat exchanger 48.

The cooling fluid (e.g., cooling water) may enter the unit 14 through the cold inlet line 20a at a temperature ranging from about 20° C. to about 40° C. In comparison, due to the heat transfer conditions in the heat exchanger 48, the cooling fluid may exit heat exchanger 48 through the outlet fluid line 50 at a temperature ranging from about 25° C. to about 60° C. (e.g., a temperature increase ranging from about 5° C. to about 20° C.).

For a smaller-scale unit 14, examples of suitable flow rates of the cooling fluid through the heat exchanger 48 (and condenser coils 68) range from about 0.1 liters/minute to about 5 liters/minute, or from about 0.5 liters/minute to about 2 liters/minute. For a larger-scale unit 14, examples of suitable flow rates of the cooling fluid through the heat exchanger 48 (and condenser coils 68) range from about 500 liters/minute to about 2,000 liters/minute, or from about 750 liters/minute to about 1,500 liters/minute.

On the other side, the unit 14 is set up to regenerate the desiccant in the sorption column 40. In this case, the controller 36 may command the inlet valve 44 to open the flow between the hot inlet line 24b and the inlet fluid line 58, which closes off access to the cold inlet line 20b. The controller 36 may also command the outlet valve 64 to open the flow between the outlet fluid line 62 and hot outlet line 26b, which closes off access to the circulation line 66.

Accordingly, the heating fluid from the heating source 18 (shown in FIG. 1) may flow under pressure through the hot inlet line 24b, inlet value 44, inlet fluid line 58, heat exchanger 60, outlet fluid line 62, outlet valve 64, hot outlet line 26b, and back to the heating source 18. In comparison, the cooling fluids in the cold inlet line 20b and circulation line 66 are closed off from the heat exchanger 60.

The heating fluid may enter the unit 14 through the hot inlet line 24b in a pressurized state at a temperature ranging from about 80° C. to about 400° C. For a smaller-scale unit 14, examples of suitable flow rates of the heating fluid through the heat exchanger 60 range from about 0.1 liters/minute to about 5 liters/minute, or from about 0.5 liters/minute to about 2 liters/minute. For a larger-scale unit 14, examples of suitable flow rates of the heating fluid through the heat exchanger 60 range from about 500 liters/minute to about 2,000 liters/minute, or from about 750 liters/minute to about 1,500 liters/minute.

The controller 36 may also command the actuating doors 102, 110, and 120 to be open, and command actuating doors 104, 112, and 118 to remain closed (as depicted in FIGS. 2 and 3). This accordingly opens the ports 98, 106, and 116. The controller 36 may also command the compressor 84 to start up, such as by relaying electrical power to the compressor 84, to generate a vapor flow through the unit 14.

In the evaporator stage 72, the refrigerant condensate 88 evaporates to generate an evaporative cooling effect due to the enthalpy of vaporization of the refrigerant. For instance, the temperature in the evaporator stage 72 may range from about −10° C. to about 10° C., or from about −5° C. to about 10° C., or from greater than about 0° C. to about 5° C. For embodiments in which the refrigerant consists essentially of water, the temperature in the evaporator stage 72 may range from greater than about 0° C. to about 10° C., or from about 1° C. to about 5° C. In some embodiments, the refrigerant may also include an anti-freeze agent to assist in further cooling effects.

The vapor pressure in the evaporator stage 72 may range from about 1 torr to about 20 torr, or from about 3 torr to about 10 torr, for example. The evaporation rate of the refrigerant condensate 88 may vary depending on the size of the unit 14. For instance, for a small window-sized unit 14, the evaporation rate of the refrigerant condensate 88 may range from about 0.1 grams/second to about 1 gram/second, or from about 0.2 grams/second to about 0.5 grams/second. For a residential-sized unit 14 (e.g., for use with a residential central air system), the evaporation rate of the refrigerant condensate 88 may range from about 1 gram/second to about 10 grams/second, or from about 3 grams/second to about 7 grams/second.

For a medium-sized commercial unit 14, the evaporation rate of the refrigerant condensate 88 may range from about 10 grams/second to about 75 grams/second, or from about 15 grams/second to about 50 grams/second. For a larger-scale unit 14, the evaporation rate of the refrigerant condensate 88 may range from about 75 grams/second to about 750 grams/second, or from about 100 grams/second to about 500 grams/second.

The reduced temperature in the evaporator stage 72 draws heat from the chilled fluid flowing through the heat exchanger 82, thereby cooling the chilled fluid down for circulation back to the heat exchanger 34 in the environment 12. Accordingly, the chilled fluid entering the heat exchanger 82 from the fluid inlet line 30 may have an incoming temperature ranging from about 20° C. to about 30° C. After leaving the heat exchanger 82 through fluid outlet line 32, the chilled fluid may have an outgoing temperature ranging from about 5° C. to about 15° C. (e.g., the chilled fluid may be cooled down by about 10° C. to about 15° C.).

For a smaller-scale unit 14, examples of suitable flow rates of the chill fluid through the heat exchanger 82 range from about 0.1 liters/minute to about 5 liters/minute, or from about 0.5 liters/minute to about 2 liters/minute. For a larger-scale unit 14, examples of suitable flow rates of the chilled fluid through the heat exchanger 82 range from about 500 liters/minute to about 2,000 liters/minute, or from about 750 liters/minute to about 1,500 liters/minute.

The refrigerant vapor (e.g., water vapor) in the evaporator stage 72 exits through the port 98 into the sorption stage 74, as illustrated by arrow 122 in FIG. 3. The vapor then passes through the desiccant bed of the sorption column 38. The cooling water flowing through the heat exchanger 48 draws heat from the desiccant bed of the sorption column 38, thereby cooling the desiccant down. The cooled desiccant accordingly adsorbs (and/or absorbs) a substantial portion of the vapor, such as from about 75% to about 99.9% by weight, or from about 85% to about 99% by weight, or from about 90% to about 99% by weight, based on the weight of the refrigerant vapor exiting the evaporator stage 72.

For example, the cooling fluid flowing through the heat exchanger 48 may remove the heat of adsorption of the vapor as it adsorbs to the desiccant, thereby trapping the refrigerant in the desiccant bed of sorption column 38. This process with the sorption column 38 may continue until the desiccant bed of the sorption column 38 becomes saturated (or substantially saturated) with the refrigerant.

As such, in preferred embodiments, only a small residual portion of the refrigerant vapor escapes the desiccant bed of the sorption column 38, and flows through the port 106 into the compressor stage 78, as illustrated by arrow 124. This residual portion of the refrigerant vapor may have about the same vapor pressure as discussed above for the evaporator stage 72, but has a mass flow rate that is much lower due to the reduced amount remaining. Accordingly, the residual portion of the vapor entering the compressor stage 78 may range from about 0.1% to about 25% by weight, or from about 1% to about 15% by weight, or from about 1% to about 10% by weight, based on the weight of the refrigerant vapor exiting the evaporator stage 72. At the compressor stage 78, the compressor 84 pressurizes and forces the residual portion of the vapor into the condenser stage 80, as illustrated by arrow 126.

While the sorption column 38 is in the active state, the sorption column 40 is in the regeneration state to remove the trapped refrigerant in its desiccant bed so that it may be freshly regenerated for subsequent use in its active state. While in the regeneration state, the heating fluid flow through the heat exchanger 60 is transferred to the desiccant bed of the sorption column 40. The transferred heat drives the refrigerant vapors out of the desiccant bed, where the refrigerant vapors flow through the port 116 into the condenser stage 80, as illustrated by arrow 128.

As can be appreciated, trapping the refrigerant vapors in the desiccant beds can significantly reduce the vapor flows to the compressor 84. Instead, the regeneration step of the sorption column 40 drives the refrigerant vapors to the condenser stage 80 in a manner that bypasses the compressor 84. This reduces the throughput requirements of the compressor 84, thereby allowing the compressor 84 to be smaller in size and have reduced power requirements.

Examples of suitable vapor pressures of the refrigerant vapors entering the condenser stage 80 from both the compressor stage 78 and the desiccant stage 40 may range from about 10 torr to about 125 torr, or from about 20 torr to about 100 torr. At condenser stage 80, the refrigerant vapors condense at the condenser coils 68, and fall into the condensate tank 86 as the refrigerant condensate 88.

At the condenser stage 80, the cooling fluid entering the condenser coils 68 from the fluid line 67 may be at about the same temperature as discussed above when exiting heat exchanger 48 through the outlet fluid line 50. In comparison, due to the heat transfer conditions in the condenser coils 68, the cooling fluid may exit the condenser coils 68 through the cold outlet line 22 at a temperature ranging from about 25° C. to about 70° C. (e.g., a temperature increase ranging from about 5° C. to about 10° C.).

The refrigerant condensate 88 may drain from or otherwise be removed from the condensate tank 86 through the condensate line 90 (e.g., pumped). At the expansion valve 92, pressure is relieved from the condensate 88, and the resulting condensate 88 flows through the refrigerant line 94 to the evaporator nozzles 96 within the evaporator stage 72. The evaporator nozzles 96 correspondingly allow the refrigerant condensate 88 to exit into the evaporator stage 72, where it may further expand and evaporate to produce the refrigerant vapor, as discussed above. The flow rate of the condensate 88 is preferably at about the same rate as the flow rate of the refrigerant vapor out of the evaporator stage 72 to substantially maintain a steady volume of the refrigerant in the evaporator stage 72.

After a given operating duration, which preferably occurs at or before the saturation limit of the sorption column 38, and preferably at or after the refrigerant vapor is removed from the sorption column 40, the controller 36 may command the unit 14 to transition the sorption stage 74 from its active state to its regeneration state, and to transition the sorption stage 76 from its regeneration state to its active state. In some embodiments, the sorption stage 76 may transition from its regeneration state to its active state prior to the sorption stage 74 switching from its active state to its regeneration state. This may allow the unit 14 to continue operating during the transition. Alternatively, the unit 14 may shut off the compressor 84 and/or the flows through the inlet fluid line 30 and the outlet fluid line 32 during the transition, and then transition the states of the sorption stage 74 and 76 in a substantially simultaneous manner.

As shown in FIG. 4, during the transition, the controller 36 may command the inlet valve 44 to open the flow between the cold inlet line 20b and inlet fluid line 58, which closes off access to the hot inlet line 24b. The controller 36 may also command the outlet valve 64 to open the flow between the outlet fluid line 62 and the circulation line 66, which closes off access to the hot outlet line 26b.

Accordingly, the cooling fluid from the cooling source 16 (shown in FIG. 1) may flow under pressure through the cold inlet line 20b, inlet value 44, inlet fluid line 58, heat exchanger 60, outlet fluid line 62, outlet valve 64, circulation line 66, manifold 56, fluid line 67, condenser coils 68, cold outlet line 22, and back to the cooling source 16 and/or a drain. In comparison, the heating fluids in the hot inlet line 24b and hot outlet line 26b are closed off from the heat exchanger 60.

On the other side, the sorption stage 74 is transitioned for regeneration. In this case, the controller 36 may command the inlet valve 42 to open the flow between the hot inlet line 24a and the inlet fluid line 46, which closes off access to the cold inlet line 20a. The controller 36 may also command the outlet valve 52 to open the flow between the outlet fluid line 50 and the hot outlet line 26a, which closes off access to the circulation line 54.

Accordingly, the heating fluid from the heating source 18 (shown in FIG. 1) may flow under pressure through the hot inlet line 24a, inlet value 42, inlet fluid line 46, heat exchanger 48, outlet fluid line 50, outlet valve 52, hot outlet line 26a, and back to the heating source 18. In comparison, the cooling fluids in the cold inlet line 20a and the circulation line 54 are closed off from the heat exchanger 48.

The controller 36 may also command the actuating doors 104, 112, and 118 to be open, and command the actuating doors 102, 110, and 120 to remain closed, as depicted in FIG. 4. This accordingly opens the ports 100, 108, and 114. As discussed above, the reduced temperature in the evaporator stage 72 may continue to draw heat from the chilled fluid flowing through the heat exchanger 82, thereby cooling the chilled fluid down for circulation back to the heat exchanger 34 in the environment 12. The refrigerant vapor (e.g., water vapor) in the evaporator stage 72 may then flow through the port 100 into the sorption stage 76, as illustrated by arrow 130 in FIG. 4. The vapor then passes through the desiccant bed of sorption column 40. The cooling water flowing through the heat exchanger 60 draws heat from the desiccant bed of sorption column 40, thereby cooling the desiccant down.

The cooled desiccant in the sorption column 40 accordingly adsorbs (and/or absorbs) a substantial portion of the refrigerant vapor, such as from about 75% to about 99.9% by weight, or from about 85% to about 99% by weight, or from about 90% to about 99% by weight, based on the weight of the refrigerant vapor exiting the evaporator stage 72. As discussed above for the heat exchanger 48, the cooling fluid flowing through the heat exchanger 60 may remove the heat of adsorption of the refrigerant as it adsorbs to the desiccant, thereby trapping the refrigerant in the desiccant bed of the sorption column 40. This process with the sorption column 40 may continue until the desiccant bed of the sorption column 40 becomes saturated (or substantially saturated) with the refrigerant.

As also discussed above, in preferred embodiments, only a small residual portion of the refrigerant vapor escapes the desiccant bed of the sorption column 40, and flows through the port 108 into the compressor stage 78, as illustrated by arrow 132. The residual portion of the refrigerant vapor may have about the same vapor pressure as discussed above for evaporator stage 72, but has a mass flow rate that is much lower due to the reduced residual amount remaining.

Accordingly, the residual portion of the refrigerant vapor entering compressor stage 78 from sorption stage 76 may also range from about 0.1% to about 25% by weight, or from about 1% to about 15% by weight, or from about 1% to about 10% by weight, based on the weight of the refrigerant vapor exiting the evaporator stage 72. At the compressor stage 78, the compressor 84 pressurizes and forces the residual portion of the refrigerant vapor into the condenser stage 80, as illustrated by arrow 134.

The sorption stage 74, on the other hand, is in the regeneration state to remove the trapped refrigerant in the desiccant bed of sorption column 38 so that it may be ready for subsequent use in its active state. While in the regeneration state, the heating fluid flow through the heat exchanger 48 is transferred to the desiccant bed of the sorption column 38. The transferred heat drives the refrigerant vapors out of the desiccant bed, where the refrigerant vapors flow through the port 114 into the condenser stage 80, as illustrated by arrow 136.

As also discussed above, trapping the refrigerant vapors in the desiccant beds can significantly reduce the vapor flows to the compressor 84. Instead, the regeneration step of the sorption column 38 drives the refrigerant vapors to the condenser stage 80 in a manner that also bypasses the compressor 84. This reduces the throughput requirements of the compressor 84, thereby allowing the compressor 84 to be smaller in size and have reduced power requirements.

Examples of suitable vapor pressures of the refrigerant vapors entering the condenser stage 80 from both the compressor stage 78 and the desiccant stage 40 include those discussed above. At condenser stage 80, the refrigerant vapors condense at the condenser coils 68, and fall into the condensate tank 86 as the refrigerant condensate 88.

The refrigerant condensate 88 may then flow to the evaporator nozzles 96 within the evaporator stage 72, as discussed below. The evaporator nozzles 96 correspondingly allow the refrigerant condensate 88 emit into the evaporator stage 72 for evaporation, as discussed above. The flow rate of the refrigerant condensate 88 is again preferably at about the same rate as the flow rate of the refrigerant vapor out of the evaporator stage 72 to substantially maintain a steady volume of the refrigerant in the evaporator stage 72.

After a given operating duration, which preferably occurs at or before the saturation limit of the sorption column 40, and preferably at or after the refrigerant vapor is removed from the sorption column 38, the controller 36 may command the unit 14 to transition the sorption desiccant stage 76 back from its active state to its regeneration state, and to transition the sorption stage 74 back from its regeneration state to its active state, as discussed above. This transition process may then be repeated in the back-and-forth manner while the unit 14 operates to provide freshly-regenerated sorption columns 38 and 40 for generating the conditioned air in the environment 12.

As can be appreciated from the above discussion, the AC system 10 and the unit 14 combine the benefits of a desiccant column and compressor in a unique manner. In particular, the interchangeable use of sorption columns 38 and 40 allows the refrigerant vapors, which are driven into the condenser stage 80 during the regeneration steps, to bypass the compressor 84. As such, the compressor 84 is not required to compress the substantial portion of the refrigerant vapors.

In comparison, compressor-based systems are typically used only for large cooling capacity (e.g., several hundred tons). These systems utilize centrifugal compressors, which are impractical for small or medium capacity units, as the required rotational speed is very high (e.g., several hundred thousand revolutions per minute). On the other hand, a positive displacement vacuum pump is also not feasible for small or medium capacity units, as it handles much smaller volume flow rate than needed even for small air conditioning units.

Instead, the unit 14 incorporates the compressor 84 that assists the flow through the sorption columns 38 and 40. Because a substantial portion of the refrigerant vapor is trapped in the columns 38 and 40, the compressor 84 may operate with a smaller capacity and size requirements. Further, small and medium capacity units 14 have the advantage of small dead volumes, and thus, frequent switching between the sorption columns 38 and 40 is achievable. This allows the sorption columns 38 and 40 themselves to be smaller in size, which accommodates smaller and lighter units 14.

Although the present disclosure has been described with reference to preferred embodiments, workers skilled in the art will recognize that changes may be made in form and detail without departing from the spirit and scope of the disclosure.

Claims

1. An air conditioning system comprising:

an evaporator stage configured to remove heat from a medium by evaporation of a refrigerant condensate, which produces a refrigerant vapor;

first and second sorption stages configured to interchangeably transition between active states and regeneration states, wherein the first and second sorption stage each comprises a sorption column configured to trap a first portion of the refrigerant vapor received while in the active state;

a compressor stage configured to receive a second portion of the refrigerant vapor from the first or second sorption stage in the active state;

a condenser stage configured to receive the refrigerant vapor from the compressor and to receive the refrigerant vapor from the first or second sorption stage in the regeneration state in a manner that bypasses the compressor stage, wherein the condenser stage is also configured to condense the received refrigerant vapors as a refrigerant condensate; and

a condensate line configured to direct a flow of the refrigerant condensate from the condenser stage to the evaporator stage.

2. The air conditioning system of claim 1, wherein the evaporator stage comprises:

a heat exchanger configured to circulate the medium; and

an evaporator configured to emit the refrigerant condensate into the evaporator stage.

3. The air conditioning system of claim 1, wherein each sorption column comprises a bed of a desiccant, wherein the desiccant comprises one or more zeolites selected from the group consisting of hydrated and/or anhydrous structures of aluminosilicate minerals, which may contain one or more of sodium (Na), potassium (K), cerium (Ce), calcium (Ca), barium (Ba), strontium (Sr), lithium (Li), and magnesium (Mg).

4. The air conditioning system of claim 1, wherein the first portion of the refrigerant vapor trapped by the sorption column of the first or second sorption stage in the active state ranges from about 75% to about 99.9% by weight of the refrigerant vapor, based on the weight of the refrigerant vapor exiting the evaporator stage.

5. The air conditioning system of claim 4, wherein the first portion of the refrigerant vapor trapped by the sorption column ranges from about 85% to about 99% by weight of the refrigerant vapor.

6. The air conditioning system of claim 5, wherein the first portion of the refrigerant vapor trapped by the sorption column ranges from about 90% to about 99% by weight of the refrigerant vapor.

7. The air conditioning system of claim 1, wherein the sorption column of the first or second sorption stage in the active state is configured to trap the first portion of the refrigerant vapor by adsorption, by absorption, or both.

8. The air conditioning system of claim 1, and further comprising a controller configured to command the first and second sorption stages to interchangeably transition between the active states and the regeneration states.

9. The air conditioning system of claim 1, wherein the refrigerant condensate consists essentially of water and optionally an anti-freeze agent.

10. An air conditioning system comprising:

an evaporator stage configured to produce a refrigerant vapor;

a first sorption stage having a first sorption column;

a second sorption stage having a second sorption column, wherein the first and second sorption stages are configured to be interchangeably used in an active state to trap a first portion of the refrigerant vapor received from the evaporator stage, and in a regeneration state to regenerate the first or second sorption column;

a compressor stage configured to receive a second portion of the refrigerant vapor from the first or second sorption stage that is the active state;

a condenser stage configured to receive the refrigerant vapor from the compressor, and to receive the refrigerant vapor from the first or second sorption stage in the regeneration state, wherein the condenser stage is also configured to condense the received refrigerant vapors as a refrigerant condensate; and

a condensate line configured to direct a flow of the refrigerant condensate from the condenser stage to the evaporator stage.

11. The air conditioning system of claim 10, wherein while the first sorption stage is in the active state, the second sorption stage is in a regeneration state, and wherein while the second sorption stage is in the active state, the first sorption stage is in the regeneration state.

12. The air conditioning system of claim 10, and further comprising:

a cold inlet line operably connected to the first and second sorption stages, wherein the cold inlet line is configured to circulate a cooling fluid through the first or second sorption column that is in the active state;

a hot inlet line operably connected to the first and second sorption stages; and

a hot outlet line operably connected to the first and second sorption stages, wherein the hot inlet line and the hot outlet line are configured to circulate a heating fluid through the first or second sorption column that is in the regeneration state.

13. The air conditioning system of claim 10, and further comprising a controller configured to interchangeably transition the first and second sorption stages between the active state and the regeneration state.

14. The air conditioning system of claim 10, wherein the refrigerant condensate consists essentially of water and optionally an anti-freeze agent.

15. The air conditioning system of claim 10, wherein the first and second sorption columns are each configured to trap the first portion of the refrigerant vapor by adsorption, by absorption, or both.

16. A method for conditioning air, the method comprising:

evaporating a refrigerant condensate in an evaporator stage to remove heat from a cooling medium, wherein the evaporation produces a refrigerant vapor;

trapping a first portion of the refrigerant vapor in a first sorption column;

passing a second portion of the refrigerant vapor through the first sorption column to a compressor stage;

pressurizing the second portion of the refrigerant vapor in the compressor stage, and forcing the pressurized portion of the refrigerant vapor into a condenser stage;

driving additional refrigerant vapor from a second sorption column to the condenser stage in a manner that bypasses the compressor stage;

condensing the pressurized portion of the refrigerant vapor and the additional refrigerant vapor in the compressor stage to produce the refrigerant condensate; and

passing the refrigerant condensate from the compressor stage to the evaporator stage.

17. The method of claim 16, and further comprising regenerating the second sorption column, which drives additional refrigerant vapor from the second sorption column to the condenser stage.

18. The method of claim 17, wherein regenerating the second sorption column comprises circulating a heating fluid through a heat exchanger retained in the second sorption column.

19. The method of claim 16, trapping the first portion of the refrigerant vapor in the first sorption column comprises:

circulating a cooling fluid through a heat exchanger retained in the first sorption column to cool a desiccant bed of the first sorption column; and

passing the refrigerant vapor from the evaporator stage through the cooled desiccant bed of the first sorption column.

20. The method of claim 16, wherein the refrigerant condensate consists essentially of water and optionally an anti-freeze agent.