DESICCANT-BASED COOLING SYSTEM
A desiccant-based system and method for conditioning air includes a first unit remotely located from an area whose environment is to be controlled. Additional units are respectively located within areas where air conditioning is desired. Each of the additional units is connected to the first unit such that desiccant can be transferred between each of the additional units and the first unit. Cool, undiluted desiccant can be transferred from the first unit to at least one of the additional units so that ambient air at the location of the additional unit can be dehumidified and cooled. Each of the additional units are separately controllable, such that the respective environments surrounding the additional units can be maintained at different levels of humidity and temperature.
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This application claims the benefit of U.S. provisional patent application No. 61/527,904 filed 26 Aug. 2011, which is hereby incorporated herein by reference.
TECHNICAL FIELDThe present invention relates to a system and method of desiccant-based air conditioning.
BACKGROUNDAir conditioning systems may utilize any of a variety of processes for heating, cooling, dehumidifying, and humidifying air. For example, a vapor-compression system may take advantage of the expansion and compression of a refrigerant to provide cooling and/or heat into different ambient spaces. Another type of air conditioning system uses a hygroscopic material, such as a desiccant, to remove or add water to an airstream, and to cool or heat an ambient environment. Examples of such systems are described in the following patent: U.S. Pat. No. 6,487,872, issued on 3 Dec. 2002, which is hereby incorporated herein by reference.
Typically desiccant-based systems employ a central unit that uses a desiccant to remove moisture from one airstream, which dilutes the desiccant, and to give up moisture from the desiccant to another airstream, thereby concentrating or regenerating the diluted desiccant. The central unit then provides the conditioned air to an ambient environment, which may be, for example, one or more rooms within a building.
One limitation of this type of desiccant system is that it may not allow for individual control of the ambient environment within different rooms in a building. Remotely locating different portions of a desiccant system—for example, by having a regenerator outdoors and a process portion indoors—can require a complex system for balancing the concentration of the desiccant between the regeneration and process activities. Thus, a need exists for a desiccant-based air conditioning system that provides individual control for one or more rooms in a building, without an unduly complex system for desiccant balance.
SUMMARYEmbodiments of the present invention provide a system and method for conditioning air using a desiccant-based system that allows individual control of the environment in one or more rooms in a building.
Embodiments of the invention include a system having a first subsystem disposed outside a building whose environment is to be controlled. A second subsystem is located inside the building, in a room where it is desired to control the environment. The second subsystem is connected to the first subsystem, such that desiccant is transferred between the first and second subsystems as required to provide the desired environment within the room.
Embodiments of the invention also include a desiccant-based air conditioning system having a first subsystem, or outdoor unit, and multiple second subsystems, or indoor units. Each of the indoor units is connected to the outdoor unit, such that desiccant can flow to and from each of the indoor units individually as required to provide separate environmental control for each of the rooms. One way this can be accomplished is by using a float-actuated valve to control the flow of desiccant into the indoor units. A temperature sensor can also be connected to the valve to provide further control so that flow of desiccant into the indoor unit can be a function of both mass and temperature of the desiccant. In this way, a computer algorithm can be employed to control the flow of desiccant into and out of the indoor units individually so that different environmental conditions can be maintained in the respective spaces where the indoor units are located.
For purposes of cooling and dehumidification, the indoor units will receive cool, concentrated desiccant from the outdoor unit, which is then brought into contact with an airflow from the inside space. The airflow may enter one portion of the indoor unit, where it gives up water to the desiccant and is simultaneously cooled. The dry, cool air is then exhausted into the ambient environment to provide the desired conditions.
The diluted desiccant may be gathered in a sump in the indoor unit and transferred back to the outdoor unit, for example, by gravity or a pump system. The diluted desiccant is regenerated in the outdoor unit, where it can be exposed to a combination of heat and a relatively dry airflow that removes water from the desiccant. In some embodiments of the invention, the heat may be provided through one or more heat exchangers that are part of a vapor-compression system. The vapor-compression system also includes at least one evaporator, and this can be the source of cooling for the desiccant that is provided to the indoor units.
The outdoor unit itself may be divided into separate chambers, a first of which, a first process chamber, receives the diluted desiccant from the indoor units and transfers regenerated desiccant to the indoor units. The second chamber in the outdoor unit performs the regeneration of the diluted desiccant by adding an airflow and/or heat to remove the water from the desiccant. The two chambers may be connected, for example, through an orifice, or some other mechanism effective to transfer the desiccant between the chambers.
In addition to the foregoing, embodiments of the present invention also provide a mechanism for humidifying and warming the indoor air that is processed by the indoor units. This can be accomplished, for example, by adding water to the desiccant in the outdoor unit so that desiccant being transferred to the indoor units contains a relatively high percentage of water. Thus, when the indoor air is processed by one of the indoor units, it picks up water from the desiccant and exhausts moist air back into the indoor environment. This may be particularly helpful in the winter in cold climates when the air is generally very dry. In this same way, the desiccant in the outdoor unit can be heated so that in addition to providing moisture to the indoor air, it warms the air as it is processed through the indoor unit.
At least some embodiments of the invention include a system for conditioning air. The system includes a first unit housing a regenerator operable to receive a first airflow and bring the first airflow into contact with a liquid desiccant to transfer water from the liquid desiccant to the first airflow. The regenerator includes a regenerator sump for collecting the liquid desiccant after water is transferred to the liquid desiccant from the first airflow, the first unit further housing a first portion of a process sump fluidly connected to the regenerator sump. A second unit is remotely located from the first unit and is configured to receive a second airflow and bring the second airflow into contact with the liquid desiccant. The second unit houses a second portion of the process sump for collecting the liquid desiccant after it contacts the second airflow. The first unit is in selective fluid communication with the second unit such that the liquid desiccant can be selectively transferred between the first and second portions of the process sump, and the liquid desiccant transferred from the second portion of the process sump to the first portion of the process sump can be admixed with the liquid desiccant in the regenerator sump prior to the liquid desiccant being returned to the second unit.
At least some embodiments of the invention include a system for conditioning air that includes a first unit remotely located from an indoor space, and a second unit located within the indoor space and in selective fluid communication with the first unit. The first unit includes a regeneration chamber into which a first airflow is introduced and contacted with a liquid desiccant to transfer water from the liquid desiccant to the first airflow. The regeneration chamber includes a regenerator sump for collecting the liquid desiccant after water is transferred to the liquid desiccant from the first airflow. The first unit further includes a first process chamber separated from the regenerator chamber such that the first airflow is inhibited from entering the first process chamber. The first process chamber includes a first portion of a process sump fluidly connected to the regenerator sump. The second unit includes a second process chamber into which a second airflow is introduced and contacted with the liquid desiccant to transfer water between the second airflow and the liquid desiccant prior to the second airflow being discharged into the indoor space. The second process chamber includes a second portion of the process sump for collecting the liquid desiccant after it contacts the second airflow. The selective fluid communication between the first and second units providing selective transfer of the liquid desiccant between the first and second portions of the process sump.
At least some embodiments of the invention include a method for conditioning air that includes bringing a first airflow into contact with a liquid desiccant in a regeneration chamber to transfer water from the liquid desiccant to the first airflow during a first mode of operation. The liquid desiccant is collected in a regenerator sump after water is transferred from the liquid desiccant to the first airflow. The liquid desiccant in the regenerator sump is admixed with liquid desiccant in a first portion of a process sump disposed in a first process chamber adjacent the regeneration chamber. Some of the liquid desiccant from the first portion of the process sump is transferred to a second portion of the process sump disposed in a second process chamber located remotely from the first process chamber. A second airflow is brought into contact with the liquid desiccant in the second process chamber to transfer water from the second airflow to the liquid desiccant during the first mode of operation. The second airflow is exhausted from the second process chamber into an ambient environment having air to be conditioned, after the second airflow has contacted the liquid in the second process chamber.
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
As shown in
As shown in
The vapor-compression system shown in
As noted above, the desiccant 34 receives heat from the heat exchanger 52, and this process helps to regenerate the desiccant 34 by driving off some of the water that has been picked up by the indoor units 14, 16, 18 from the air in their respective indoor spaces 20, 22, 24. In addition to using heat to drive off some of the moisture from the desiccant 34, the outdoor unit 12 also uses an airflow to further remove moisture. As shown in
In addition to receiving information regarding the level of the desiccant 34, the valve 70 also receives information from a temperature sensor 78, which measures the temperature of the desiccant 34 in the sump 76. The valve 70 may be, for example, a three-way electronically actuated solenoid valve, which responds to certain inputs, including inputs from the float system 74 and the temperature sensor 78. Control of the valve 70 may be part of a larger control system that also coordinates and controls the operation of the various components of the outdoor unit shown in
When the inputs to the valve 70, such as the level of the desiccant 34 indicated by the float system 74 and/or the temperature of the desiccant 34 as indicated by the temperature sensor 78, indicate that the valve 70 should be opened, desiccant from the outdoor unit 12 is provided to the indoor unit 14, as shown by the dashed line 80. In warm, humid environments, the desiccant 34 entering the indoor unit 14 from the outdoor unit 12 will be cool and relatively dry—i.e., undiluted by water. As explained below, this allows the ambient air in the room 20 to be dehumidified and cooled to a desired level.
At some point, some of the desiccant 34 will be pumped back into the outdoor unit as indicated by the dashed line 94 shown in
Because the indoor units 14, 16, 18 are separately controlled and serve spaces that may have different requirements, the float system 74 may be actuated frequently in some units, while in other units it is actuated very infrequently. In at least some situations, the airflow 86, 86′ may recirculate many times through a particular indoor unit before the float system 74 is actuated. This is another advantage of having the process side of a desiccant-based air conditioning system split between the outdoor unit and the individual indoor units—i.e., transfer of desiccant from the indoor units does not need to be based on the concentration of the desiccant in the indoor unit sump (although it can be); rather, it can be based on a temperature or strictly on a volume of liquid in the indoor sump. In this way, the more complex control of balancing the concentration of the desiccant is handled entirely in the outdoor unit, independent of the indoor units.
The air conditioning described above operates in a first mode of operation to cool and dehumidify ambient air inside a room. The system 10 can, however, also condition air to have an opposite effect—i.e., the system 10 can be operated in a second mode of operation to warm and increase the humidity of ambient air within a space. One way that this can be accomplished is to provide additional water directly to the outdoor unit 12. This is illustrated in
In addition to adding water to the desiccant 34, it is also possible to add heat to the desiccant 34 so that a warm, dilute desiccant can be provided to the indoor units 14, 16, 18. Heat can be added by any method effective to achieve the desired result, such as operating the vapor-compression system in reverse. As shown in
Alternatively, the system 10 can be provided with solar collectors that are either physically attached or remotely operated to provide heat and/or electricity to the system 10. When this process is followed, the warm, dilute desiccant 34 is passed over the media 84—see FIG. 3A—where moisture and heat are collected by the second airflow 86—see FIG. 3B—prior to its being exhausted back into the ambient environment.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.
Claims
1. A system for conditioning air, comprising:
- a first unit housing a regenerator operable to receive a first airflow and bring the first airflow into contact with a liquid desiccant to transfer water from the liquid desiccant to the first airflow, the regenerator including a regenerator sump for collecting the liquid desiccant after water is transferred to the liquid desiccant from the first airflow, the first unit further housing a first portion of a process sump fluidly connected to the regenerator sump; and
- a second unit remotely located from the first unit and configured to receive a second airflow and bring the second airflow into contact with the liquid desiccant, the second unit housing a second portion of the process sump for collecting the liquid desiccant after it contacts the second airflow, the first unit being in selective fluid communication with the second unit such that the liquid desiccant can be selectively transferred between the first and second portions of the process sump, and the liquid desiccant transferred from the second portion of the process sump to the first portion of the process sump can be admixed with the liquid desiccant in the regenerator sump prior to the liquid desiccant being returned to the second unit.
2. The system of claim 1, wherein the regenerator sump and the first portion of the process sump are separated by a divider having an aperture disposed therein for facilitating diffusion of the liquid desiccant therebetween.
3. The system of claim 1, wherein the first unit is located outside a building and is configured to receive and exhaust the first airflow from and to an ambient outdoor environment, and the second unit is located inside the building and is configured to receive and exhaust the second airflow from and to an ambient environment inside the building.
4. The system of claim 1, wherein the first and second units are operable in a first mode of operation to transfer water from the second airflow to the liquid desiccant, and in a second mode of operation to transfer water from the liquid desiccant to the second airflow, when the second airflow is brought into contact with the liquid desiccant in the second unit.
5. The system of claim 4, wherein the regenerator is configured to be shut down during the second mode of operation to inhibit evaporation of water from the liquid desiccant in the regenerator sump.
6. The system of claim 4, wherein the first unit further houses at least a portion of a refrigeration system configured to selectively heat and cool the liquid desiccant through heat transfer with a refrigerant.
7. The system of claim 6, wherein the first unit houses at least an evaporator of the refrigeration system, and includes a first process pump configured to pump the liquid desiccant from the first portion of the process sump through the evaporator during the first mode of operation to transfer heat from the liquid desiccant to the refrigerant prior to the liquid desiccant being transferred to the second unit and brought into contact with the second airflow.
8. The system of claim 7, further comprising a bypass valve configured to return a portion of the liquid desiccant leaving the evaporator to the first portion of the process sump prior to the liquid desiccant being transferred to the second unit.
9. The system of claim 6, wherein the first unit includes a regenerator pump configured to pump the liquid desiccant from the regenerator sump through a condenser of the refrigeration system during the first mode of operation to receive heat from the refrigerant prior to being brought into contact with the first airflow.
10. The system of claim of claim 9, wherein the refrigeration system further includes a second condenser configured to further cool the refrigerant prior to an expansion phase of the refrigerant.
11. A system for conditioning air, comprising:
- a first unit remotely located from an indoor space; and
- a second unit located within the indoor space and in selective fluid communication with the first unit,
- the first unit including a regeneration chamber into which a first airflow is introduced and contacted with a liquid desiccant to transfer water from the liquid desiccant to the first airflow, the regeneration chamber including a regenerator sump for collecting the liquid desiccant after water is transferred to the liquid desiccant from the first airflow,
- the first unit further including a first process chamber separated from the regenerator chamber such that the first airflow is inhibited from entering the first process chamber, the first process chamber including a first portion of a process sump fluidly connected to the regenerator sump,
- the second unit including a second process chamber into which a second airflow is introduced and contacted with the liquid desiccant to transfer water between the second airflow and the liquid desiccant prior to the second airflow being discharged into the indoor space, the second process chamber including a second portion of the process sump for collecting the liquid desiccant after it contacts the second airflow, the selective fluid communication between the first and second units providing selective transfer of the liquid desiccant between the first and second portions of the process sump.
12. The system of claim 11, further comprising a plurality of the second units, each located within a respective indoor space and each in selective fluid communication with the first unit.
13. The system of claim 11, wherein the regenerator chamber and the first process chamber are separated by a divider having an aperture disposed between the regenerator sump and the first portion of the process sump for facilitating diffusion of the liquid desiccant therebetween.
14. The system of claim 11, wherein the first and second units are operable in a first mode of operation to transfer water from the second airflow to the liquid desiccant, and in a second mode of operation to transfer water from the liquid desiccant to the second airflow, when the second airflow is brought into contact with the liquid desiccant in the second unit.
15. The system of claim 14, wherein the first unit further houses at least a portion of a refrigeration system configured to selectively heat and cool the liquid desiccant through heat transfer with a refrigerant.
16. The system of claim 15, wherein the first unit houses at least an evaporator of the refrigeration system, the first process chamber including a first process pump configured to pump the liquid desiccant from the first portion of the process sump through the evaporator during the first mode of operation to transfer heat from the liquid desiccant to the refrigerant prior to the liquid desiccant being transferred to the second unit and brought into contact with the second airflow.
17. The system of claim 16, further comprising a bypass valve configured to return a portion of the liquid desiccant leaving the evaporator to the first portion of the process sump prior to the liquid desiccant being transferred to the second unit, thereby allowing the first portion of the process sump to retain the cooled desiccant.
18. The system of claim 17, wherein the regeneration chamber includes a regenerator pump configured to pump the liquid desiccant from the regenerator sump through a condenser of the refrigeration system during the first mode of operation to receive heat from the refrigerant prior to being brought into contact with the first airflow.
19. A method for conditioning air, comprising:
- bringing a first airflow into contact with a liquid desiccant in a regeneration chamber to transfer water from the liquid desiccant to the first airflow during a first mode of operation;
- collecting the liquid desiccant in a regenerator sump after water is transferred from the liquid desiccant to the first airflow;
- admixing the liquid desiccant in the regenerator sump with liquid desiccant in a first portion of a process sump disposed in a first process chamber adjacent the regeneration chamber;
- transferring some of the liquid desiccant from the first portion of the process sump to a second portion of the process sump disposed in a second process chamber located remotely from the first process chamber;
- bringing a second airflow into contact with the liquid desiccant in the second process chamber to transfer water from the second airflow to the liquid desiccant during the first mode of operation; and
- exhausting the second airflow from the second process chamber into an ambient environment having air to be conditioned, after the second airflow has contacted the liquid in the second process chamber.
20. The method of claim 19, further comprising inhibiting the first airflow from contacting the liquid desiccant in the regeneration chamber during a second mode of operation; and bringing a second airflow into contact with the liquid desiccant in the second process chamber to transfer water from the liquid desiccant to the second airflow during the second mode of operation.
Type: Application
Filed: Aug 27, 2012
Publication Date: Sep 17, 2015
Applicant: DUCOOL, LTD. (Hoff Hacarmel)
Inventor: Dan Forkosh (Atlit)
Application Number: 14/241,254