System and method for managing water content in a fluid

A system and method for managing water content in a fluid includes a collection chamber for collecting water from the fluid with a desiccant, and a regeneration chamber for collecting water from the desiccant and transferring it to a second fluid. An evaporator cools the desiccant entering the collection chamber, and a second evaporator cools the second fluid to extract the water. The evaporators use a refrigerant, the flow of which is controlled by a flow control valve. When the temperature in the second evaporator drops below a set point, the refrigerant flow to the second evaporator is stopped, and the refrigerant flow to the first evaporator is increased. This increases the water collection in the collection chamber, and causes a rise in the temperature in the second evaporator. The valve is then opened to increase the cooling in the second evaporator.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates a system and method for managing water content in a fluid.

2. Background Art

Conventionally, water is collected from air, or other gaseous fluids, using condensation systems. An exemplary condensation system provides a surface cooled to a temperature that is at or below the dew point of incoming air. As is well known in the art, the cooling of air at or below its dew point causes the condensation of water vapor from the air and a decrease in the absolute humidity of the air. The humidity of a volume of air is substantially determinative of the amount of water that can be introduced into, or removed from, the volume of air.

Conventional water generation and removal systems collect water vapor from incoming airflows using condensation systems that lower the temperature of incoming air to a temperature that is at or below the dew point of the air. Therefore, the quantity of water produced by such systems depends on the humidity of the ambient air. The humidity and temperature of air varies, however, from region to region, with hot and humid air in tropical and semitropical regions, and cooler, less humid air in other parts of the world. The temperature and water vapor content of air also varies widely with seasonal weather changes in regions throughout the year. Therefore, depending on the region of the world, and depending on the time of year, humidification or dehumidification may be desirable, for example, to make an environment more comfortable.

In addition to increasing comfort, management of the amount of water in air may be important to industrial applications. Moreover, it may be desirable to remove water from air so that the water can be utilized, for example, for drinking, or in other applications where fresh water is desired. Regardless of the reason for managing the amount of water in the air, there are times when conventional water management systems have undesirable limitations. For example, when the dew point of the air is low, particularly when it is below the freezing point of water, it may be difficult or impossible to remove the water using a conventional system. The use of a desiccant material may be effective to remove water from air or other fluid streams in such situations. Conventional systems utilizing desiccants do not account for changes in environmental conditions—e.g., changing temperature and humidity of the fluid stream—which may adversely affect the efficiency of the system.

Therefore, there is a need for a system and method for managing the water content in a fluid that can extract water from the fluid even when the dew point is low. There is also a need for a system and method for managing water content in a fluid that can control desiccant parameters to maintain system efficiency, for example, in light of changing environmental conditions.

SUMMARY OF THE INVENTION

Embodiments of the present invention provide a system and method for removing water from a fluid even when the dew point is low.

Embodiments of the invention also provide a system and method for removing water from a fluid using a desiccant having at least one parameter which can be controlled to modify the water removal capacity of the desiccant and maintain system efficiency in light of changing environmental conditions.

Embodiments of the invention further provide a system for managing water content in a fluid. The system includes a first chamber having an inlet and an outlet for facilitating movement of a first fluid into and out of the first chamber. A desiccant is capable of being introduced into the first chamber for removing water from the first fluid moving through the first chamber. A second chamber is configured to receive at least a portion of the desiccant after it removes water from the first fluid. The second chamber includes an inlet and an outlet for facilitating movement of a second fluid into and out of the second chamber. This facilitates evaporation of water from the desiccant into the second fluid, thereby increasing water content in the second fluid. A system heat exchanger is configured to receive a third fluid therethrough, and to receive the second fluid from the second chamber to facilitate a transfer of heat from the second fluid to the third fluid. This facilitates removal of water from the second fluid. A valve is operable to control the flow of the third fluid through the system heat exchanger. A sensor is in communication with the valve, and is configured to sense a parameter of the second fluid after its water content is increased. The sensor is configured to output signals to the valve related to the sensed parameter. This effects control of the flow of the third fluid through the system heat exchanger based on the sensed parameter.

The system can also include a first heat exchanger configured to receive the third fluid therethrough and to cool the desiccant before it is introduced into the first chamber. The first heat exchanger is arranged with the valve such that a reduction in flow of the third fluid through the valve increases the flow of the third fluid through the first heat exchanger. This increases the cooling capacity of the first heat exchanger.

Embodiments of the invention further provide a system for managing water content in a fluid. The system includes a first chamber having an inlet and an outlet for facilitating movement of a first fluid into and out of the first chamber. A desiccant is capable of being introduced into the first chamber for removing water from the first fluid moving through the first chamber. A second chamber is configured to receive at least a portion of the desiccant after it removes water from the first fluid. The second chamber includes an inlet and an outlet for facilitating movement of a second fluid into and out of the second chamber. This facilitates evaporation of water from the desiccant into the second fluid, thereby increasing water content in the second fluid. A heat exchanger arrangement having a controllable heat exchange capacity is configured to receive the second fluid from the second chamber to facilitate cooling of the second fluid. This facilitates removal of water from the second fluid. A sensor is configured to sense a parameter of the second fluid after its water content is increased, and is capable of outputting signals related to the sensed parameter. A control system, including at least one controller, is in communication with the heat exchanger arrangement and the sensor. The control system is configured to receive signals from the sensor and to effect control of the heat exchange capacity of the heat exchanger arrangement based at least in part on the signals received.

Embodiments of the invention further provide a method for managing water content in a fluid using a system which includes a desiccant and a system heat exchanger. The method includes removing water from a first fluid using a process that includes exposing at least some of the first fluid to the desiccant. This increases the water content of at least some of the desiccant. At least some of the desiccant having increased water content is introduced into a second fluid, thereby facilitating evaporation of water from the desiccant into the second fluid and increasing water content of the second fluid. The second fluid is passed through the system heat exchanger after the water content of the second fluid is increased. This facilitates cooling of the second fluid and removal of water therefrom. A parameter of the second fluid is sensed after its water content is increased, and the heat exchange capacity of the system heat exchanger is controlled at least partly based on the sensed parameter.

Embodiments of the present invention also provide a system and method for passing ambient air into a first chamber having a suitable desiccant material therein. The desiccant absorbs or adsorbs moisture from the air that comes in contact with the desiccant. In one embodiment, the air contacts desiccant by pumping air through a contact surface, such as a sponge, media, cooling coil, or cooling tower, that has desiccant dispersed therein. The desiccant and/or first chamber may be cooled to enable the more efficient transfer of water from the air to the desiccant. The desiccant absorbs or adsorbs water from the air, thereby transferring latent heat from the air as the water undergoes a phase change and condenses out of the air. Because the desiccant and/or first chamber are cooled, sensible cooling—i.e., cooling that is not based on a change of state—is also provided to the air. The resulting dry, cooled air is drawn out from the first chamber.

The now hydrous desiccant collects at the bottom of the first chamber and gets transferred to a second chamber. The second chamber transfer occurs either through active pumping or diffusion via a valve opening provided in a partition between the first and the second chambers. The valve opening enables equalization of desiccant levels in the first and the second chamber. The net flow of hydrous desiccant occurs from the first chamber to the second chamber until the level of the desiccant equalizes in the two chambers. The diffused or pumped hydrous desiccant in the second chamber can be heated and then again exposed to air.

The desiccant can be introduced into the chambers by any method effective to achieve the desired result. For example, the first chamber may include spongy cellulose material through which the hydrated desiccant percolates down to collect at the bottom of the chamber. Alternatively, the desiccant is made to simply drip in the form of drops from points within, such as the top of, the first and second chambers. In one embodiment, the desiccant is sprayed into the interior of the second chamber. A heat exchanger such as a heating element warms the spray of hydrous desiccant falling from the nozzles, thereby evaporating moisture absorbed or adsorbed into the desiccant, generating hot humid air, and also regenerating substantially anhydrous desiccant.

The hot, humid air leaving the second chamber can be directed to contact the dew-forming surfaces of a heat absorber, such as an evaporator, that are cooled using a suitable cooling process such as classic boiling fluids contained in tubes, thermoelectric elements, heat pipes, refrigerant-expansion coils or any other system known to persons of ordinary skill in the art. A parameter of the hot, humid air can be sensed—e.g., the humidity or the temperature, and the heat absorbing capacity of the evaporator can be appropriately controlled. For example, if the sensed temperature drops below a set point, the heat absorbing capacity of the evaporator can be reduced. At the same time, the desiccant entering the first chamber can be further cooled, for example, by increasing the heat absorbing capacity of a heat exchanger through which the desiccant is passed. This will ultimately lead to an increased load in the evaporator, which will cause the temperature to rise above the set point, thereby leading to an increase in the heat absorbing capacity of the evaporator. In this way, changing environmental conditions are accounted for, and the overall efficiency of the system is increased.

At least one embodiment of the present invention can sterilize and filter the condensed water to generate pure drinking water. Accordingly, in one embodiment, condensed water from the condensate collector is exposed to suitable ultra-violet (UV) radiation in a UV unit to free the water from harmful microscopic organisms. Additionally, the radiated water is serially passed through a charcoal filter to remove contaminants and Volatile Organic Compounds (VOC's) and a plurality of mineral cartridges to mineralize and/or vitaminize the water. The purified and mineralized water is collected in a first storage tank. Additionally, the water is passed through an oxygenator before being stored in the first storage tank. Water from the first storage tank is recirculated through the UV unit at predetermined intervals of time to maintain quality of water.

At least one embodiment of the present invention can also dispense hot and cold water. Thus, in one embodiment, water from the first storage tank is gravity fed into a second cold storage tank from where it is further gravity fed into a third hot storage tank. Water in the second storage tank is chilled using a suitable cooling process such as Peltier-effect or chemical/magnetic cooling, by the use of a typical expansion-evaporation coils, or by any other method effective to achieve the desired result. The cold water is then dispensed through a first childproof spigot. Also, water in the third tank is heated to a desired temperature by a heating element and dispensed through a second spigot. Ambient temperature water is dispensed from the second spigot when power is disallowed to the heating element of the third tank. In another embodiment, water from the first storage tank can be directly dispensed through a third spigot to provide water at ambient temperature.

Embodiments of the present invention may also be configured to provide for the introduction of water from external sources in the event of low condensate formation. Accordingly, an external source such as a municipal supply faucet is attached through quick-disconnect fittings to supply supplemental water to the first storage tank.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

FIG. 1shows a system10for managing water content in a fluid in accordance with one embodiment of the present invention. In particular, the system10is configured to manage the water content in air—either to collect water from the air for storage and subsequent use, or to control the humidity of the air. It is worth noting that although the examples presented herein utilize ambient air as the fluid whose water content is being managed, the present invention is capable of managing the water content of other fluids as well—e.g., gases, liquids, or some combination thereof. The system10includes a first chamber, or collection chamber12, and a second chamber, or regeneration chamber14. The collection chamber12includes an inlet16and an outlet18which allow a first airflow19to flow through the collection chamber12. As the air flows through the collection chamber12, it contacts a desiccant20, which, in the embodiment shown inFIG. 1, is sprayed into the chamber12via a conduit22.

As the air moves through the collection chamber12, vaporized water is condensed out, and collects with the desiccant20in the bottom portion24of the chamber12. The desiccant20is diluted as it adsorbs or absorbs the water from the air. Although the desiccant20shown inFIG. 1is all liquid, the present invention contemplates the use of solid desiccants, or dual phase desiccants—e.g., solid and liquid. Any desiccant material effective to produce the desired result may be used, including solids, liquids, solutions, aqueous solutions, mixtures, and combinations thereof. Lithium chloride (LiCl) and calcium chloride (CaCl2) are typical of liquid desiccant solutions, but other liquid desiccants may be employed.

Still other types of desiccants such as montmorillonite clay, silica gel, molecular sieves, CaO, CaSO4 can all be used. As would be evident to persons of ordinary skill in the art, the selection of a desirable desiccant depends, among other parameters, upon the temperature and humidity ranges of ambient air from which moisture is to be absorbed. Still other exemplary desiccants comprise materials such as P2O5, BaO, Al2O3, NaOH sticks, KOH fused, CaBr2, ZnCl2, Ba(ClO4)2, ZnBr2.

As noted above, the desiccant20is a liquid desiccant, which may comprise an aqueous solution of 40% lithium chloride. Inside the collection chamber12is a matrix material23. The matrix23can be a sponge or other medium or media effective to facilitate contact between the desiccant20and the air flowing through the collection chamber12. The desiccant20is pumped into the conduit22by a pump26. The pump26pumps the desiccant20through a first heat exchanger28prior to its introduction into the collection chamber12. By cooling the desiccant20, its ability to remove water from the first airflow19is increased. A fluid, such as a refrigerant, is passed through the heat exchanger28via conduits30,32. The desiccant20is cooled in the heat exchanger28to a temperature below that of the first airflow19In this way, the airflow19is cooled as it passes through the collection chamber12. As an alternative to the heat exchanger28, a heat exchanger may be placed inside the collection chamber12to cool the first airflow19directly, or to cool the desiccant20after it is sprayed into the collection chamber12.

The regeneration chamber14also includes an inlet34and an outlet36, which facilitate movement of a second airflow38into and out of the regeneration chamber14. As with the collection chamber12, the regeneration chamber14also includes a pump40which is used to pump the desiccant20into the regeneration chamber14through a conduit42. The desiccant20is sprayed into the regeneration chamber14to contact a matrix44, which, like the matrix23, may be a sponge or other medium or media.

Between the two chambers12,14is a flow controller46, which can be an electronic valve, operable to allow the hydrous desiccant from the collection chamber12to mix with desiccant in the regeneration chamber14, and vice versa. Instead of the valve46, other flow control devices may be used to control the flow of desiccant between the two chambers12,14. For example, a partition may be used for equalization in concentration of the desiccant20, which can be achieved through osmotic flow. In this way, the desiccant20in the collection chamber12is not rapidly diluted and rendered ineffective.

The pumps26,40can pump the desiccant20into their respective chambers12,14through respective conduits45,47. Alternatively, some or all of the desiccant20can be pumped from one of the chambers12,14, to the other of the chambers12,14through the flow controller46. In some embodiments of the present invention, a flow controller, such as the flow controller46, can have two inlets connected directly to respective pump outlets, and two outlets connected directly to respective heat exchanger inlets, thereby eliminating the need for conduits45,47. In some embodiments, the flow through the valve46is much less than the flow through the respective conduits45,47. For example, if the pumps26,40have a flow rate of 200 liters per minute (lpm), the flow through the valve46may be 100 liters per hour (lph). Thus, only a fraction of the fluid pumped by the pumps26,40is pumped into the opposite chamber14,12, respectively. Conversely, other embodiments of the present invention may have pumps and flow controllers with different flow rates—both in terms of absolute flow rates and in terms of flow rates relative to each other.

As shown inFIG. 1, the desiccant20is pumped by the pump40through a second heat exchanger48. Heat can be added to the heat exchanger48from any convenient source, via conduits50,52. By passing through the heat exchanger48, the desiccant20is heated to a temperature above the temperature of the second airflow38, so that the second airflow38is heated as it passes through the regeneration chamber14. By heating the second airflow38, more water is evaporated from the desiccant20into the second airflow38. As an alternative to the heat exchanger48, which is located outside the regeneration chamber14, a heat exchanger (not shown) may be located inside the regeneration chamber14.

Use of the system10results in two separate airflows exiting the chambers12,14. The first airflow19of now dry air exits the collection chamber12through the outlet18, and the second airflow38of now humid air exits the regeneration chamber14through the outlet36. One of ordinary skill in the art will appreciate that the extraction of water from the first airflow19increases the latent heat of the desiccant20, and results in latent cooling of the first airflow19. Additionally, because the desiccant20(or alternatively the chamber12, or both) is cooled, the first airflow19itself undergoes sensible cooling that lowers its temperature level, thereby creating cooled, dry air. In one embodiment, the present invention uses 10 liters of lithium chloride solution to extract 2 liters per hour of moisture from incoming air that is provided by an air blower rated at 250 m3/hour. The result is a sensible cooling capacity of 0.7 kilowatts (kW) and a latent cooling capacity of 1.4 kW, thereby enabling a temperature reduction in the air of 8.4° C.

The warm, humid air38leaving the regeneration chamber14can be introduced into a system heat exchanger, or evaporator54. The evaporator54includes a contact surface56, which causes water58to condense out of the humid air stream38. The water58may be collected in a storage tank60for later use. Depending on the use intended for the water58, it can be sterilized and/or treated using a secondary system, or by expanding the system10to include such elements. One such system is described in International Patent Application PCT/US05/30529 filed on 26 Aug. 2005, entitled “System and Method for Producing Water,” which is hereby incorporated herein by reference.

The evaporator54is part of a refrigeration subsystem62, which includes the first and second heat exchangers28,48. The first and second heat exchangers28,48respectively act as an evaporator and condenser within the subsystem62. A third fluid, or refrigerant, is pumped through the subsystem62by a compressor64, while throttling devices66,68facilitate expansion of the refrigerant before it reaches a respective evaporator28,54.

To selectively control the flow of the refrigerant through the evaporators28,54, a control valve70is used. The control valve70is in communication with a sensor72at least partly disposed within the evaporator54. The sensor72is configured to sense a parameter of the second airflow38after it has picked up water in the regeneration chamber14. For example, the sensor72can be a hygrometer or other device capable of measuring the humidity of the airflow38, which may be convenient when the system10is used as a dehumidifier. Alternatively, the sensor72can be a temperature sensor configured to sense a temperature of the airflow38, which may be convenient when the system10is used to produce water. In any case, the sensor72can output signals related to the sensed parameter to control the valve70.

In the embodiment shown inFIG. 1, the sensor72is configured to sense the temperature of the airflow38in the evaporator54. When the valve70is open, thereby allowing refrigerant to flow through the evaporator54, the evaporator54cools the airflow38. The sensor72is configured such that when the sensed temperature drops to a predetermined set point—e.g., 3° C.—the sensor72signals the valve70to close. This stops the refrigerant from flowing through the evaporator54, and increases the amount of refrigerant flowing through the other evaporator, or first heat exchanger28. In this way, the heat absorbing capacity of the evaporator54is reduced—i.e., its cooling capacity is reduced—while the heat absorbing capacity of the evaporator28is increased. The increased cooling of the desiccant20entering the collection chamber12results in more water being absorbed from the first airflow19, and thereby increases the vapor pressure of the desiccant20. In other embodiments, a sensor, such as the sensor72, can include a hygrometer, configured to measure the humidity of the airflow38. In such embodiments, a sensed humidity at or below a set point humidity can cause signals to be sent to close the valve70, again reducing the cooling capacity of the evaporator54and automatically increasing the cooling capacity of the evaporator28.

In situations where the moisture content in the airflows19,38is low, the set point—temperature or humidity—will quickly be reached, and the desiccant20entering the collection chamber12will receive increased cooling. This results in an increase in the amount of water collected in the collection chamber12and subsequently transferred to the regeneration chamber14through the flow controller46. This, in turn, causes a higher load in the regeneration chamber14, and ultimately, an increase in the temperature sensed by the sensor72. In order to keep the valve70from constantly cycling between open and shut, a hysteresis can be built in to the system10. In this way, the valve70may be shut when the sensed temperature is at one set point, but it may not be opened until the sensed temperature reaches another set point, slightly higher than the first set point.

In the system10, either or both of the sensor72and the valve70may include one or more controllers which can be programmed, for example, with temperature or humidity set points. In addition, the flow controller46can be programmed to appropriately manage the flow of the desiccant20between the collection and regeneration chambers12,14. Thus, the system10includes a control system made up of independently operating controllers. Alternatively, a system controller can be used to coordinate the functions of the various elements of the system; such a system is illustrated inFIG. 2. InFIG. 2, the prime symbol (′) has been used to identify elements which are related to those found in the system10shown inFIG. 1.

FIG. 2illustrates a system10′ for managing the water content in air. As with the system10, shown inFIG. 1, the system10′ includes collection and regeneration chambers12′,14′, each of which has its own heat exchanger28′,48′ for controlling the temperature of the desiccant20′. The heat exchangers28′,48′ are part of a refrigeration subsystem62′. The refrigeration subsystem62′ also includes a heat exchanger arrangement74, which includes a heat exchanger, or evaporator54′, and a refrigerant flow valve70′. Although the evaporator54′ is shown separately from the flow control valve70′, it is understood that they can be integrated into a single device, which can also include a sensor72′ Similar to the sensor72, shown inFIG. 1, the sensor72′ is configured to sense a parameter of the airflow38′—e.g., temperature, humidity, etc.—and to output signals related to the sensed parameter.

Rather than relying on a number of independent controllers, the system10′ includes a system controller76, which communicates with other controllers—e.g., the flow controller46′ and a controller or controllers within the valve70′ and the sensor72′—to make up a control system. As shown inFIG. 2, the system controller76can be used to control other elements of the system10′, such as pumps26′,40′. This configuration may conveniently provide a centralized control of the various elements in a system, such as the system10. Similar to the system10, shown inFIG. 1, the system10′ can function to modify the heating or cooling capacities of various system elements to accommodate changing environmental conditions.