CHILLER SYSTEMS AND METHODS

Abstract

The disclosure relates to chiller systems and, more particularly, to chiller systems that employ electrically driven desiccant regenerators. In some examples, a chiller system includes a heat and mass exchanger and an electrically driven desiccant regenerator in fluid communication with the heat and mass exchanger. The heat and mass exchanger is configured to dehumidify a flow of air, and provide the dehumidified flow of air to a cooling tower. Further, the electrically driven desiccant regenerator is configured to provide concentrated liquid desiccant to the heat and mass exchanger for dehumidifying the flow of air.

Description

TECHNICAL FIELD

The disclosure relates generally to chiller systems and, more particularly, to chiller systems with cooling towers.

BACKGROUND

Chiller systems are used to control temperature within structures, such as equipment or buildings. Typically, chiller systems control the temperature by circulating a liquid, such as water or aqueous mixture, through the structure. The liquid is cooled during a refrigerant cycle. Some chiller systems include cooling towers that cool water. The cooled water may be used by a condenser of the chiller system to cool the hot refrigerant.

SUMMARY

In some embodiments, a chiller system includes a heat and mass exchanger and an electrically driven desiccant regenerator in fluid communication with the heat and mass exchanger. The heat and mass exchanger is configured to dehumidify a flow of air, and provide the dehumidified flow of air to a cooling tower. Further, the electrically driven desiccant regenerator is configured to provide concentrated liquid desiccant to the heat and mass exchanger for dehumidifying the flow of air.

In some embodiments, a method is performed by a chiller system. The method includes providing, by an electrically driven desiccant regenerator, concentrated liquid desiccant to a liquid desiccant reservoir. The method also includes receiving, by a heat and mass exchanger, the concentrated liquid desiccant from the liquid desiccant reservoir. Further, the method includes receiving, by a channel of the heat and mass exchanger, outside air to be dehumidified by the concentrated liquid desiccant. The method also includes providing, by the heat and mass exchanger, the dehumidified air to an interior of a cooling tower for cooling water. Additionally, the method includes providing, by the heat and mass exchanger, diluted liquid desiccant to the liquid desiccant reservoir. The method also includes receiving, by the electrically driven desiccant regenerator, the diluted liquid desiccant from the liquid desiccant reservoir for liquid desiccant regeneration, wherein said water cooled by the cooling tower is provided to a condenser of the chiller system.

BRIEF DESCRIPTION OF THE DRAWINGS

The following drawings are illustrative of particular embodiments of the present disclosure and therefore do not limit the scope of the present disclosure. The drawings are not to scale and are intended for use in conjunction with the explanations in the following detailed description.

FIG. 1 illustrates a chiller system, in accordance with some embodiments;

FIG. 2 illustrates a chiller system, in accordance with some embodiments;

FIG. 3 illustrates a chiller system, in accordance with some embodiments;

FIG. 4 illustrates a chiller system, in accordance with some embodiments;

FIG. 5 illustrates an electrically driven desiccant regenerator that can be used in the chiller systems of FIGS. 1, 2, 3, and 4, in accordance with some embodiments; and

FIG. 6 is a flowchart of a method to provide dehumidified air to a cooling tower of a chiller system, in accordance with some embodiments.

DETAILED DESCRIPTION

The following discussion omits or only briefly describes conventional features of chiller systems that are apparent to those skilled in the art. It is noted that various embodiments are described in detail with reference to the drawings, in which like reference numerals represent like parts and assemblies throughout the several views. Reference to various embodiments does not limit the scope of the claims attached hereto. Additionally, any examples set forth in this specification are intended to be non-limiting and merely set forth some of the many possible embodiments for the appended claims. Further, particular features described herein can be used in combination with other described features in each of the various possible combinations and permutations.

Unless otherwise specifically defined herein, all terms are to be given their broadest reasonable interpretation including meanings implied from the specification as well as meanings understood by those skilled in the art and/or as defined in dictionaries, treatises, etc. It must also be noted that, as used in the specification and the appended claims, the singular forms “a,” “an” and “the” include plural referents unless otherwise specified, and that the terms “includes” and/or “including,” when used in this specification, specify the presence of stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, steps, operations, elements, components, and/or groups thereof. In the description, relative terms such as “horizontal,” “vertical,” “up,” “down,” “top,” and “bottom” as well as derivatives thereof (e.g., “horizontally,” “downwardly,” “upwardly,” etc.) should be construed to refer to the orientation as then described or as shown in the drawing figure under discussion. These relative terms are for convenience of description and normally are not intended to require a particular orientation. Terms including “above” versus “below,” “inwardly” versus “outwardly,” “longitudinal” versus “lateral,” and the like are to be interpreted relative to one another or relative to an axis of elongation, or an axis or center of rotation, as appropriate. Terms concerning attachments, coupling, and the like, such as “connected” and “interconnected,” refer to a relationship wherein structures are secured or attached to one another either directly or indirectly through intervening structures, as well as both movable or rigid attachments or relationships, unless expressly described otherwise. The terms “operatively connected,” “operably connected,” and the like are such attachments, couplings, or connections that allow the pertinent structures to operate as intended by virtue of that relationship.

Embodiments of the present disclosure relate generally to chiller systems and, more particularly, to chiller systems that employ an electrically driven desiccant regenerator to provide dehumidified air to a cooling tower of the chiller system. Among other advantages, the dehumidified air increases the rate of water evaporation within the cooling tower, increasing potential heat transfer and efficiency of the cooling tower. Moreover, the electrically driven desiccant regenerator (EDDR), which cools high-pressure gas from the compressor, may reduce the load on the compressor. Persons of ordinary skill in the art may recognize these and other advantages as well.

For instance, in some embodiments, a chiller system includes an electrically driven desiccant regenerator that provides concentrated liquid desiccant to a heat and mass exchanger (e.g., parallel plate or air-to-air heat and mass exchanger). Outside air passes through a channel (e.g., conditioning channel) of the heat and mass exchanger, and is dehumidified by the concentrated liquid desiccant. After proceeding through the channel of the heat and mass exchanger, the flow of air passes into a cooling tower of the chiller system. The dehumidified air proceeds up through the cooling tower, evaporating water that is sprayed down through the cooling tower. Because the air is dehumidified prior to entering the cooling tower, the rate and amount of water evaporation is increased. Moreover, the temperature of the water that is captured by the cooling tower is reduced (e.g., due to more evaporative cooling compared to conventional chiller systems).

The chiller system may also include a compressor that receives low pressure refrigerant from an evaporator, and provides pressurized refrigerant to a condenser. The condenser receives the cool, collected water from the cooling tower, and uses the cool, collected water to condense the pressurized refrigerant. Because the temperature of the water that is captured by the cooling tower described herein is lower than using conventional cooling towers, the compressor can operate at higher efficiencies (e.g., with lower power). Further, the condenser provides the condensed refrigerant back to the evaporator, which uses the condensed refrigerant to, for example, cool warm water (e.g., for a building).

Referring to the drawings, FIG. 1 illustrates a chiller system 100 that may receive warm water 129 from a building 130, and cools the warm water 129 to provide cool water 127 (e.g., cold water) back to the building 130. For instance, in some examples, building 130 may be a data center housing various electronic equipment, such as servers and networking equipment. The warm water 129 from a data center may be, for instance, in the range of 50 to 70 degrees Celsius. Chiller system 100 includes an evaporator 108, a compressor 110, a condenser 104, an expansion valve 106, an electrically driven desiccant regenerator 120, a liquid desiccant reservoir 122, a heat and mass exchanger 124, and a cooling tower 102.

Electrically driven desiccant regenerator 120, which is powered by electricity 119, receives diluted (e.g., low concentration (25-40% salt)) liquid desiccant 115 from the liquid desiccant reservoir 122, evaporates water from the diluted liquid desiccant 115 to generate concentrated (e.g., high concentration (50-65% salt)) liquid desiccant, and provides the concentrated liquid desiccant 113 back to the liquid desiccant reservoir 122. In some embodiments, the liquid desiccant will separate based on density so that concentrated liquid desiccant settles to the bottom of the liquid desiccant reservoir 122, while low concentration liquid desiccant rises to the top of the liquid desiccant reservoir 122. In some instances, the liquid desiccant is a non-corrosive liquid desiccant.

In some embodiments, the heat and mass exchanger 124 is configured to allow air 131, such as outside air, to pass through one or more channels. As the air 131 passes through the channels of the heat and mass exchanger 124, the air 131 is dehumidified. To dehumidify the air 131, the heat and mass exchanger 124 receives concentrated liquid desiccant 121 from the liquid desiccant reservoir 122, and distributes the concentrated liquid desiccant 121 along surfaces within the heat and mass exchanger (e.g., along wicking media) such that the air 131 comes into contact with the concentrated liquid desiccant 121, thereby dehumidifying the air 131 to provide dehumidified air 133 to the cooling tower 102. After passing along the sides of the channels to dehumidify the air 131, the heat and mass exchanger 124 provides the diluted liquid desiccant 141 back to the liquid desiccant reservoir 122.

Further, the dehumidified air 133 enters the cooling tower 102. As illustrated, the cooling tower 102 includes a fan 126 that draws the dehumidified air 133 up through the cooling tower 102. The cooling tower 102 receives hot water 107 from the condenser 104. The hot water 107 enters into a sprayer 128 that distributes (e.g., sprays out) the hot water 107 into the cooling tower 102. As the hot water 107 droplets are released from the sprayer 128, the hot water 107 droplets fall through the interior of the cooling tower 102. A portion of the water droplets evaporates into the dehumidified air 133 which cools the droplets to provide cold water 103 at the bottom of the cooling tower 102. As described herein, the dehumidified air 133 allows for more efficient cooling of the hot water 107 droplets than conventional chiller systems. For instance, because more water can evaporate into the dehumidified air 133 before reaching the dew point, there can be more cooling so the cold water 103 may achieve cooler temperatures than conventional chiller systems, and/or may be cooled to a same temperature more efficiently.

Referring back to FIG. 1, the cooling tower 102 collects the cold water 103, and provides the cold water 103 along with, in some examples, make-up water 105 (e.g., additional water to make up for evaporation, for instance) back to the condenser 104. The make-up water 105 can be from a municipal source or another source of cool water. The condenser 104 uses the cold water 103 to condense pressurized refrigerant 111 received from the compressor 110, and provides condensed refrigerant 109 to the expansion valve 106. The condensed refrigerant 109 may enter the expansion valve 106 under relatively higher pressure. The expansion valve 106 reduces the pressure of the condensed refrigerant 109 upstream of the evaporator 108, thereby providing lower pressure, cold refrigerant 123 to the evaporator 108. The evaporator 108 uses the cold refrigerant 123 to cold the warm water 129 from the building 130 to provide the cool water 127 to the building 130.

FIG. 2 illustrates a chiller system 200 that includes evaporator 108, compressor 110, condenser 104, expansion valve 106, electrically driven desiccant regenerator 120, liquid desiccant reservoir 122, heat and mass exchanger 124, and cooling tower 102. In this exemplary chiller system 200, in addition to the features described with respect to FIG. 1, the electrically driven desiccant regenerator 120 receives warm water 203 from the building. The warm water 203 may be, for instance, a portion of the warm water 129 provided to the evaporator 108. In some instances, the warm water 203 may act as a heat transfer fluid that transfers heat generated within building 130 (e.g., heat generated by electronic equipment within a data center) to the electrically driven desiccant regenerator 120. The electrically driven desiccant regenerator 120 may be configured to use the warm water 203 to pre-heat scavenging air entering the electrically driven desiccant regenerator 120, thereby reducing electricity consumption, such as that provided by electricity 119.

FIG. 3 illustrates a chiller system 300 that includes evaporator 108, compressor 110, condenser 104, expansion valve 106, electrically driven desiccant regenerator 120, liquid desiccant reservoir 122, heat and mass exchanger 124, and cooling tower 102. Chiller system 300 further includes an indirect evaporative cooler 302 that can reduce the temperature of the dehumidified air 133 entering the cooling tower 102.

For example, the indirect evaporative cooler 302 may include a conditioning channel through which the dehumidified air 133 passes through. The conditioning channel may provide for indirect evaporative cooling of the dehumidified air 133, thereby lowering the temperature of the dehumidified air 133, before the dehumidified air 133 enters the cooling tower 102. In this embodiments, the air is dehumidified before entering the indirect evaporative cooler 302, which allows for more efficient cooling because the sensible heat load of water vapor has been reduced significantly before cooling.

FIG. 4 illustrates a chiller system 400 that includes evaporator 108, compressor 110, expansion valve 106, electrically driven desiccant regenerator 120, liquid desiccant reservoir 122, heat and mass exchanger 124, and cooling tower 102. Chiller system 400 further includes a condenser 404 that is located within the interior of the cooling tower 102. Although located within cooling tower 102, the condenser 404 receives pressurized refrigerant 111 from the compressor 110, and provides condensed refrigerant 109 to the expansion valve 106. In some examples, the liquid desiccant held by the liquid desiccant reservoir 122 is a non-corrosive liquid desiccant.

FIG. 5 illustrates an example of an electrically driven desiccant regenerator 120. As illustrated, a desiccant concentrator 502 receives diluted liquid desiccant 115 from a desiccant reservoir 520, evaporates water from the diluted liquid desiccant 115 to generate concentrated liquid desiccant, and provides the concentrated liquid desiccant 113 back to the liquid desiccant reservoir 122.

To evaporate water from the diluted liquid desiccant 115, the desiccant concentrator 502 receives concentrated refrigerant 523 from a compressor 512. At least a portion of the concentrated refrigerant 523, warm refrigerant 531, is provided to a first stage 506 of the electrically driven desiccant regenerator 120, which may be a boiler. The first stage 506 of the electrically driven desiccant regenerator 120 provides first stage conditioned refrigerant 505, which proceeds to an expansion valve 504. The expansion valve 504 de-pressurizes the first stage conditioned refrigerant 505 to provide de-pressurized refrigerant 517 to a second state 508 of the electrically driven desiccant regenerator 120. The second stage 508 of the electrically driven desiccant regenerator 120 may be a scavenging-air regenerator, for example. In addition, one or more fans may push or draw a flow of outside air 509 through the desiccant concentrator 502, which is provided out as a flow of exhaust air 511, thereby assisting in the cooling of the refrigerant.

Further, the second stage 508 of the electrically driven desiccant regenerator 120 receives the de-pressurized refrigerant 517 and provides second stage conditioned refrigerant 521 back to the compressor 512. A water recovery unit 510 may collect water 513 from the second stage 508 of the electrically driven desiccant regenerator 120. The compressor 512 pressurizes the second stage conditioned refrigerant 521 to provide the concentrated refrigerant 523 to the desiccant concentrator 502.

The liquid desiccant reservoir 122 can store enough concentrated liquid desiccant to operate for extended periods of time. Thus, during high demand times, the liquid desiccant reservoir 122 of FIGS. 1-5, can provide the liquid desiccant to the chiller system. However, the electrically driven desiccant regenerator 120 can regenerate liquid desiccant during low demand times (e.g., early morning hours, when building 130 is not occupied, when there is low demand for electronic equipment housed by building 130, etc.). For example, in some embodiments, the liquid desiccant reservoir 122 can be size to run 12 hours or more (e.g., 15 hours or more, 18 hours or more, 21 hours or more, or 24 hours or more). Thus, rather than having the electrically driven desiccant regenerator 120 regenerate liquid desiccant as needed, regardless of the energy demand on the local grid, the liquid desiccant reservoir provides a way to shift the regeneration of the liquid desiccant to more desirable times (e.g., during periods of lower electricity cost).

FIG. 6 illustrates a flowchart of a method that can be carried out by, for example, the chiller system 100 of FIG. 1. Beginning at block 602, an electrically driven desiccant regenerator provides concentrated liquid desiccant to a liquid desiccant reservoir. At block 604, a heat and mass exchanger receives concentrated liquid desiccant from the liquid desiccant reservoir. Further, at block 606, a channel of the heat and mass exchanger receives outside air to be dehumidified by the concentrated liquid desiccant. For instance, a fan may blow the outside air to the channel of the heat and mass exchanger, which is dehumidified within the channel as the concentrated liquid desiccant flows along portions of one or more sides of the channel. After dehumidification, the heat and mass exchanger may collect the now diluted liquid desiccant.

Proceeding to block 608, the dehumidified air exits the channel of the heat and mass exchanger, and is provided to an interior of a cooling tower for cooling water. At block 610, the heat and mass exchanger provides the diluted liquid desiccant back to the liquid desiccant reservoir. Further, at block 612, the electrically driven desiccant regenerator receives the diluted liquid desiccant from the liquid desiccant reservoir for liquid desiccant regeneration.

The various embodiments described above are provided by way of illustration only and should not be construed to limit the claims attached hereto. Those skilled in the art will readily recognize various modifications and changes that may be made without following the example embodiments and applications illustrated and described herein, and without departing from the spirit and scope of the following claims.

Claims

1. A chiller system, comprising: a heat and mass exchanger configured to: dehumidify a flow of air; andprovide the dehumidified flow of air to a cooling tower; andan electrically driven desiccant regenerator in fluid communication with the heat and mass exchanger, the electrically driven desiccant regenerator configured to provide concentrated liquid desiccant to the heat and mass exchanger for dehumidifying the flow of air.

2. The chiller system of claim 1 comprising a liquid desiccant reservoir, wherein: the liquid desiccant reservoir is in fluid communication with the electrically driven desiccant regenerator and the heat and mass exchanger;the electrically driven desiccant regenerator is configured to provide the concentrated liquid desiccant to the liquid desiccant reservoir; andthe heat and mass exchanger is configured to receive the concentrated liquid desiccant from the liquid desiccant reservoir.

3. The chiller system of claim 2, wherein: the liquid desiccant reservoir is configured to receive diluted liquid desiccant from the heat and mass exchanger; andthe electrically driven desiccant regenerator is configured to receive the diluted liquid desiccant from the liquid desiccant reservoir.

4. The chiller system of claim 1, wherein the cooling tower is configured to release hot water to fall down through a cavity of the cooling tower, and wherein the dehumidified air cools the hot water as the hot water falls down through the cavity to provide cooled water.

5. The chiller system of claim 4 comprising a condenser in fluid communication with the cooling tower, wherein the cooling tower is configured to receive the hot water from the condenser.

6. The chiller system of claim 5, wherein the cooling tower is configured to collect the cooled water and provide the cooled water to the condenser for condensing refrigerant.

7. The chiller system of claim 5, wherein the chiller system comprises an expansion valve, and wherein the condenser is configured to: receive refrigerant from a compressor;condense the refrigerant to generate condensed refrigerant; andprovide the condensed refrigerant to the expansion valve.

8. The chiller system of claim 7, wherein the chiller system comprises an evaporator, and wherein the expansion valve is configured to: depressurize the condensed refrigerant to generate depressurized refrigerant; andprovide the depressurized refrigerant to the evaporator.

9. The chiller system of claim 8, wherein the evaporator is configured to: receive warm water from a structure;use the depressurized refrigerant to cool the warm water to provide cold water; andprovide the cold water to the structure.

10. The chiller system of claim 9, wherein the structure is a data center.

11. The chiller system of claim 1, wherein the electrically driven desiccant regenerator is configured to: receive warm water from a structure, andpre-heat scavenging air entering the electrically driven desiccant regenerator.

12. The chiller system of claim 1 comprising an indirect evaporative cooler in fluid communication with the heat and mass exchanger and the cooling tower, wherein the indirect evaporative cooler is configured to: receive the dehumidified flow of air from the heat and mass exchanger;cool the dehumidified flow of air; andprovide the cooled and dehumidified flow of air to the cooling tower.

13. A method comprising: providing, by an electrically driven desiccant regenerator, concentrated liquid desiccant to a heat and mass exchanger for dehumidifying a flow of air;dehumidifying, by the heat and mass exchanger, the flow of air; andproviding, by the heat and mass exchanger, the dehumidified flow of air to a cooling tower.

14. A method performed by a chiller system comprising: providing, by an electrically driven desiccant regenerator, concentrated liquid desiccant to a liquid desiccant reservoir;receiving, by a heat and mass exchanger, the concentrated liquid desiccant from the liquid desiccant reservoir;receiving, by a channel of the heat and mass exchanger, outside air to be dehumidified by the concentrated liquid desiccant;providing, by the heat and mass exchanger, the dehumidified air to an interior of a cooling tower for cooling water;providing, by the heat and mass exchanger, diluted liquid desiccant to the liquid desiccant reservoir; andreceiving, by the electrically driven desiccant regenerator, the diluted liquid desiccant from the liquid desiccant reservoir for liquid desiccant regeneration, wherein said water cooled by the cooling tower is provided to a condenser of the chiller system.