WO2016085895A1

WO2016085895A1 - System and method for the handling of a fluid in a heat and mass exchanger

Info

Publication number: WO2016085895A1
Application number: PCT/US2015/062254
Authority: WO
Inventors: Philip C. FARESE; Hari K. KANAGALA; Fariduddin BEHZAD
Original assignee: Ducool Usa Inc. D/B/A Advantix Systems
Priority date: 2014-11-24
Filing date: 2015-11-24
Publication date: 2016-06-02

Abstract

A system is disclosed that provides for the transfer and distribution of a liquid, such as a liquid desiccant, to and within a heat and mass exchanger for transfer of heat and mass between the liquid and a stream of a gas, such as air, without introducing droplets of the liquid into the gas, or otherwise mixing the liquid into the stream of the gas leaving the heat and mass exchanger. The system also provides for the extraction of droplets of the liquid from the stream of the gas leaving the heat and mass exchanger. These embodiments greatly reduce the volume of carryover, e.g. to a level that is negligible from the standpoint of maintenance requirements and downstream corrosion.

Description

SYSTEM AND METHOD FOR THE HANDLING OF A FLUID IN A HEAT AND

MASS EXCHANGER

Cross-Reference to Related Application

[1001] This application claims priority to and the benefit of U.S. Provisional Application No. 62/083,725, filed November 24, 2014, which is incorporated herein by reference in its entirety.

Background

[1002] The embodiments described herein relate generally to dehumidification and/or air conditioning systems, and more particularly, to the transfer to, and distribution of a liquid desiccant in a heat and mass exchanger, and retention of the liquid desiccant in the exchanger.

[1003] Continued focus on energy efficient means of providing comfort are changing the nature of air conditioning loads in buildings and are increasing the focus of building owners to manage the building using less energy. While continued efforts reduce the sensible portion of a building's air conditioning load, little focus has been drawn to reducing the latent load. Generally, this has resulting in pushing traditional heating, ventilating, and air conditioning (HVAC) equipment to operate inefficiently to meet these latent loads in the face of decreasing sensible loads, such as, for example, by over-cooling and/or reheating air.

[1004] In some instances, desiccant dehumidification has been used to increase the efficiency of HVAC systems. For example, some known systems use a solid desiccant wheel that can adsorb water from an airstream. In some instances, liquid desiccant air conditioning (LDAC) systems can be used to increase efficiency of HVAC systems. For example, LDAC systems can cool a fluid (i.e., liquid desiccant) with a low partial pressure of water to transfer heat and mass from the air to be treated into this desiccant. Some such systems can incorporate a method for managing the water content of this liquid desiccant, typically by applying heat to a portion of the liquid desiccant and passing it through a second heat and mass exchanger, thereby transferring moisture and heat collected by the liquid desiccant (e.g., in the first heat and mass exchanger) into air to be exhausted from the building.

[1005] Efficient heat and mass transfer requires some interaction between the cooled desiccant and the air to be treated as well as the heated desiccant and the air to be exhausted. One such heat and mass exchanger transfers the cool liquid desiccant onto a media bed. This desiccant then flows counter, with, or across the air to be treated. This approach represents the optimal heat transfer as it avoids a membrane or other interface between the air and desiccant that would represent an impediment to heat and mass transfer.

[1006] Traditionally this approach has resulted in a phenomenon termed "carryover." Carryover can arise from multiple physical mechanisms that arise when the air and desiccant interact. Formation of droplets and the resulting aerosol represent the primary mechanism of generating carryover. Presence of liquid desiccant in the treated air can cause multiple problems. Removal of desiccant from the system in the form of carryover represents a maintenance requirement as the desiccant removed must be replaced. Often the desiccant contains a high salt content causing this carryover to introduce a second, and more significant, concern: increased corrosion rates. The presence of salt aerosol in the treated air can greatly accelerate corrosion of any metallic elements downstream of the FTVAC equipment.

[1007] Thus, a need exists to reduce or eliminate carryover of desiccant salts from the heat and mass exchanger.

Summary

[1008] Systems, apparatus and methods for transfer of liquid desiccant to, and distribution of liquid desiccant within a heat and mass exchanger, and retention of the liquid desiccant to reduce or eliminate carryover, are described herein.

[1009] Disclosed embodiments provide for the transfer and distribution of a liquid, such as a liquid desiccant, to and within a heat and mass exchanger for transfer of heat and mass between the liquid and a stream of a gas, such as air, without introducing droplets of the liquid into the gas, or otherwise mixing the liquid into the stream of the gas leaving the heat and mass exchanger. The system also provides for the extraction of droplets of the liquid from the stream of the gas leaving the heat and mass exchanger. These embodiments greatly reduce or eliminate the volume of carryover, e.g. to a level that is negligible from the standpoint of maintenance requirements and downstream corrosion.

Brief Description of the Drawings

[1010] FIG. 1 is a schematic illustration of a fluid treatment system according to an embodiment. [1011] FIG. 2 is a perspective view of a fluid treatment system according to an embodiment.

[1012] FIGs. 3 A and 3B are front and side views of the fluid treatment system of FIG. 2.

[1013] FIG. 4 is a perspective view of a block of matrix material of the heat and mass exchanger of the fluid treatment system of FIG. 2.

[1014] FIG. 5 is a perspective view of the fluid dispenser of the fluid treatment system of FIGs. 2 A and 2B.

[1015] FIG. 6 is a perspective view of an element of the fluid dispenser of FIG. 3.

[1016] FIGs. 7A and 7B are partial views of FIGs. 3A and 3B, illustrating flow paths for a gas through the heat and mass exchanger and the extractor.

Detailed Description

[1017] In some embodiments, a system includes a dispenser, a heat and mass exchanger and an extractor. The dispenser is coupleable to a source of a liquid (e.g., liquid desiccant) and configured to convey the liquid from an inlet of the dispenser to an outlet of the dispenser. The heat and mass exchanger is disposed adjacent to the outlet of the dispenser and configured to (1) receive the liquid discharged from the outlet of the dispenser, (2) conduct a stream of a gas (e.g., humid air) through the heat and mass exchanger between an inlet portion and an outlet portion of the heat and mass exchanger, and (3) treat the stream of the gas by contacting the stream of the gas with the liquid to transfer heat energy and water between the liquid and the gas to produce a treated stream of the gas (e.g., dehumidified air) at the outlet portion of the heat and mass exchanger. The extractor is disposed adjacent to the outlet of the heat and mass exchanger and configured to eliminate any of the conveyed liquid from the treated stream of gas such that the treated gas has a negligible amount of the liquid once it leaves the extractor.

[1018] FIG. 1 is a schematic diagram of a fluid treatment system 100. Fluid treatment system (or "system") 100 can include a dispenser 120 operatively coupled to a heat and mass exchanger (or "exchanger") 1 10 to convey to the exchanger 1 10 a liquid, such as a liquid desiccant, and distribute the liquid across the exchanger 110. The liquid can be brought into contact with a gas, such as air, within the heat and mass exchanger 1 10 to enable exchange between the liquid and the gas of: a) heat energy, e.g. cool the gas by transferring heat from the gas to the liquid; and/or b) mass, e.g. reduce the moisture content of the gas by transferring water from the gas to the liquid. The system 100 can also include an extractor 130 operatively coupled to the exchanger 1 10, which can operate to extract, or separate, any of the liquid that may become entrained in a stream of the gas emerging from the exchanger 110.

[1019] Dispenser 120 operates to: a) convey the liquid from a reservoir or other source of the liquid to the exchanger 110; and b) distribute the liquid across the exchanger 1 10: i) with a suitable degree of uniformity across the exchanger 110; ii) at a suitable mass flow rate to achieve the required rate of heat and mass transfer between the liquid and the gas; and iii) under conditions that minimize or prevent the formation of aerosols or droplets of the liquid that can be entrained in the stream of the gas. The suitable degree of uniformity of distribution of the liquid across the exchanger is driven by various factors, and subject to various constraints. There is a relationship between: a) the mass or volume flow rate of the gas through the exchanger, and the temperature and water content of the gas; b) the mass or volume-specific capacity of the gas to exchange heat energy and water with the liquid; c) the relative partial pressure of water between the liquid (e.g. liquid desiccant) and the gas (e.g. humid air), which is dependent on the temperature of the liquid and the concentration of water in the liquid); d) the effective surface area of the exchanger 110 on which the liquid is carried, to form a film (which is a physical area de-rated by a degree of uniformity of wetting or lack thereof); and thus e) the mass flow rate of the liquid required to enable a desired amount of heat energy and water transfer between the liquid and the gas.

[1020] Heat and mass exchanger 110 operates to extract water and/or heat energy form the gas stream. The amount of heat energy and water transfer, and the rate of the transfer per unit volume or area of the exchanger depend on the properties of the exchanger's materials and the transfer mechanism. For example, one suitable implementation of an exchanger transfer zone for use with a liquid (such as a liquid desiccant) employs a matrix material that defines multiple flow paths through which the liquid can flow in one direction and the gas can flow in the opposite direction, such that the gas flows across the surface of the liquid and heat energy and water can be transferred between the liquid and the gas at their interface. In other embodiments, the liquid can flow in the same direction as the gas, or can flow in any direction relative to the gas.

[1021] Multiple factors are relevant to the design of the heat and mass exchanger. These include, but are not limited to, the effect the exchanger has on the stream of gas (e.g., a drop in pressure, the direction of the stream), the area of interaction between the gas stream and the liquid, and the material selected for the exchanger. In one embodiment, the matrix material can be in the form of a matrix of corrugated cellulose fiber sheets, in which the corrugations are joined at their peaks to form flow channels between them. Alternatively the matrix material can be in the form of bundles of tubes, such as straws, in a regular pattern such as close-packed hexagons (e.g., like a honeycomb pattern) or in a random packing. This allows the exchanger to have sufficient area of interaction while controlling the impact of the exchanger on the pressure of the gas stream. The exchanger is preferably made of a material with a high affinity for the liquid so the liquid adheres to the exchanger, often termed "wetting" of the material, while flowing through the gas stream. Often such a material is specified by the "wetting angle" of the material; a material with a small wetting angle is desired so the liquid stays attached to the exchanger as the air and liquid move relative to each other. This prevents droplets of the liquid from becoming detached from the surface of the exchanger and carried into the gas stream.

[1022] The required mass flow rate of the liquid, and the required degree of uniformity of distribution across the exchanger, is preferably accomplished in a manner that: a) minimizes or prevents the formation of aerosols or droplets of the liquid in the gas, particularly relatively smaller droplets (e.g. below 30 microns); and b) minimizes or prevents the entrainment of any such aerosols or droplets in the stream of the gas passing through the exchanger. The dispenser 120 may suitably employ one or more pipes or other conduits to convey the liquid from the source or reservoir of the liquid to the exchanger 110 and to distribute the liquid across the exchanger. To transfer the liquid from the one or more pipes or conduits to the exchanger material (e.g. the matrix discussed above), the fluid may be expelled through orifices in the pipes onto the exchanger material, where it can be conducted through flow passages in the exchanger material.

[1023] The pressure at which the liquid is conveyed through the pipes or conduits should be higher throughout the exchanger 110 than the pressure of the gas outside the pipes, such that the gas cannot enter the pipes through any one of the orifices, which would lead to air entrainment into the pipe and subsequent formation of aerosol or droplets when the liquid is expelled for the orifices. The positive pressure differential between the liquid inside the pipes and the gas outside the pipes should maintained at or above a level high enough to deliver the required mass flow rate of the liquid to all areas of the exchanger 110. However, the positive pressure differential between the liquid inside the pipes and the gas outside the pipes is preferably also maintained below a level at which the pressure drop through any one of the orifices produces a spray and/or at which a stream of the liquid impacts the surface of the exchanger medium and creates droplets by splashing. Thus, there is a range of positive pressure differential values that are suitable, this range is preferably small, and this range should be maintained in the dispenser 120 throughout the exchanger 110.

[1024] Aerosols or droplets of the liquid can be formed by the interaction of the stream of the gas passing over the liquid as it passes between the orifices in the dispenser 120 and the surface of the exchanger material. An important factor in the formation of droplets is the distance over which the liquid passes through the stream of the gas, i.e. a greater distance increases the formation of droplets. Droplets that do form in the gas as it moves from the orifices to the surface of the exchanger material may be entrained in the stream of the gas, or may arrive at the surface of the exchanger material and be absorbed or retained there. Greater distance between the orifices and the exchanger material also corresponds to more entrainment of droplets. Thus, it is preferable to minimize the distance, or free path length, between each of the orifices in the dispenser 120 and the nearest surface of the exchanger material.

[1025] The gas can also pick up and entrain fluid from the surface of the exchanger material. The primary factor in this entrainment is the velocity of the gas over the surface of the exchanger material. Thus, the exchanger material is preferably sized and configured such that nowhere in the exchanger does the velocity of the gas exceed the value at which the liquid can be entrained into the stream of the gas. The maximum desired velocity of the gas is dependent on the heat exchanger design, including the wetting angle of the material as described above.

[1026] Extractor 130 operates to extract, or separate, any of the liquid, e.g. aerosol or droplets, that may become entrained in the stream of the gas emerging from the exchanger 110. Extractor 130 may operate on the principle of flow diversion, i.e. routing the stream of the gas through a tortuous path with relatively small radii of curvature of the changes in direction of the flow path, such that the momentum of any droplet above a certain size (e.g. 30 microns) is too large for drag on the droplet produced by the flow velocity of the air stream in which the air stream is entrained to alter the path of the droplet sufficiently to navigate the changes in direction of the flow path. The larger droplets thus impact the wall of the extractor 130 bounding the flow path. Thus, extractor 130 can be disposed downstream (in the stream of the gas) of the exchanger 1 10, and of the dispenser 120, to collect, or extract, any droplets above a selected size (e.g. 30 microns) that are entrained by the stream of the gas from the exchanger and/or the dispenser.

[1027] The extractor can have an inlet portion that is disposed adjacent to the outlet portion of the heat and mass exchanger. The extractor can be configured to (1) conduct the treated stream of the gas through the extractor between the inlet portion of the extractor and an outlet portion of the extractor, and (2) extract droplets of the liquid contained in the treated stream of the gas and to discharge from the outlet portion of the extractor a re-treated stream of the gas substantially devoid of droplets of the liquid.

[1028] An embodiment of a fluid treatment system incorporating the features and principles discussed above in connection with FIG. 1 is shown in FIGs. 2-7B. Fluid treatment system 200 includes heat and mass exchanger 210, dispenser 220, and extractor 230.

[1029] In this embodiment, exchanger 210 is implemented with a matrix material, in particular an assembly of blocks 212 of corrugated cellulose fiber sheets. This can be seen in FIGs. 3A-3B. An individual block 212 is shown in FIG. 4. In this embodiment, the corrugations in each block 212 are oriented at an angle, e.g. approximately 45°, to the longitudinal axis of exchanger 210, i.e. to the overall direction of flow of the gas through the exchanger. Blocks 212 are arranged in a three dimensional array, with columns and rows of blocks in a vertical layer or sheet. The orientations of the blocks within a layer can be the same, as shown in FIG. 3A, or can be varied or alternated by row and/or column. Similarly, the orientations of the blocks within adjacent vertical layers can be the same or can be varied. Collectively, the channels formed by the corrugations in the blocks' constituent sheet material provide a flow path for the gas to flow through the exchanger 210. Exchanger 210 is sized, and its constituent blocks 212 are configured, to provide sufficient flow area for, and suitably low resistance to, the flow of a desired volumetric or mass flow rate of the gas. The channels also form a flow path for the liquid to flow through the exchanger 210. The corrugations, and thus the channels, have a regular pitch or spacing "S," (shown in FIG. 4) which will be referenced below in connection with the discussion of dispenser 220.

[1030] In this embodiment, dispenser 220 is implemented with a manifold 222 of connected pipes that carry the liquid from a manifold inlet 223 to a set of distribution tubes 226, as shown in FIG. 5. In this embodiment, the manifold 222 includes primary pipes 224 and secondary pipes 225, coupled to each other and to distribution tubes 226 by suitable fittings. Although in this embodiment the dispenser 220 is formed of separate components joined by fittings, in other embodiments, the dispenser 220 can be monolithically formed. The dispenser 220 can be formed of any suitable material for contacting and conveying the liquid (e.g., liquid desiccant) without experiencing an undesirable chemical reaction (e.g., corrosion) of the dispenser 220 by the liquid. Examples of suitable materials include stainless steel, aluminum, plastics and the like.

[1031] A distribution tube 226 is shown in more detail in FIG. 6. As can be seen in FIG. 6, each distribution tube 226 includes numerous orifices 227 through the lower side of the tube, through which the first fluid can be expelled towards exchanger 210. In this embodiment, the orifices 227 are arranged at about the bottom of the tube such that a portion of the liquid expelled from each orifice contacts the exchanger material.

[1032] The orifices 227 can be sized and/or shaped in any suitable manner to expel the liquid to the blocks 212. In this embodiment, the orifices 227 are sized to maintain a positive pressure differential between the liquid inside the distribution tubes 226 and the gas outside the distribution tubes 226 sufficient to (1) deliver the required mass flow rate of the liquid to all areas of the exchanger 110, and (2) prevent a pressure drop large enough to result in undesirable spray of the liquid from the orifices 227 and/or splashing of the liquid when contacting the blocks 212.

[1033] To ensure that the distribution tubes 226 are sufficiently full of the liquid, the total flow area between the manifold inlet 223 and the orifices can decrease slightly, i.e. the flow area of the manifold inlet 223 is equal to or slightly larger than the total flow area of the upstream ends of the primary pipes 224, which in turn is slightly larger than the total flow area of the upstream ends of the secondary pipes 225, which in turn is slightly larger than the total flow area of the upstream ends of the distribution tubes 226, which in turn is slightly larger than the total flow area of the orifices. In this manner, the pressure drop experienced by the liquid from the manifold inlet 223 to the orifices 227 can be small enough that the liquid desiccant exits the orifices 227 having (1) a pressure higher than the pressure of the gas outside the dispenser 220, and (2) a pressure small enough to prevent too large a pressure differential between the liquid inside the dispenser 220 and the gas outside the dispenser 220, thereby preventing any undesirable spray of the liquid as it exits the orifices 227 and/or undesirable impact or splashing of the liquid as it contacts the blocks 212 of the exchanger 210.

[1034] The momentum, or velocity, of the liquid as it moves from the orifice to the surface of the exchanger preferably has a low enough magnitude to prevent splashing as the liquid contacts the exchanger and is oriented in a direction to minimize or eliminate any portion of the path where the liquid is not in contact with the tube or the exchanger. The velocity of the liquid exiting the orifices depends on the total orifice flow area (which, as discussed above, is equal to or less than the flow area of the manifold inlet 223) and the desired volumetric flow rate of the liquid. Thus, the total flow area of the orifices is selected so that the desired volumetric flow rate of the liquid can be delivered while maintaining the velocity at which the liquid leaves the orifices below the value at which spraying or splashing would occur.

[1035] After proper adhesion of the liquid to the surface of the exchanger material, the liquid can flow based in part on gravitational force along the surface of the flow channels through each block 212. In this manner, the liquid can be conveyed to and distributed across the exchanger with suitable uniformity, and form a suitable and substantially uniform liquid film thickness on the surfaces of the channels in each block 212 of the exchanger 210. In effect, the orifices 227 being arranged in such a manner can reduce and/or limit formation of droplets and/or entrainment of any such droplets in the stream of the gas as the gas passes through the exchanger 210.

[1036] The orifices 227 can be arranged in any suitable manner to promote uniform transfer of a sufficiently large total flow rate the liquid to the blocks 212 of the exchanger 210, and to minimize the formation of droplets or entrainment of such droplets in the gas as it flows through the exchanger 210. In this embodiment, the orifices are spaced relative to one another at a relatively constant pitch or spacing "S" that is similar to, and preferably the same as, the pitch or spacing "S" of the channels in the blocks 212 of the exchanger 210 (as shown in FIG. 4). With this spacing, each orifice is positioned to expel and direct a portion of the liquid towards a corresponding channel in a given block 212. Similarly stated, each target surface or channel receives the liquid from one or more orifices. By suitably spacing the orifices, and by sizing the total orifice area, as described above, to deliver the requisite total flow rate of the liquid at an acceptable fluid velocity, substantially all of the available surface area of the exchanger 210 can be wetted with the liquid. This maximizes the heat and mass transfer capacity of exchanger 210.

[1037] Moreover, the distance between each orifice 227 and its corresponding target surface (i.e., the free path length as described above) can be minimized for all of the orifices 227, resulting in minimization of formation of droplets and entrainment of such droplets in the gas throughout all flow paths of the liquid as the liquid flows through the exchanger 210. [1038] To further promote uniformity of flow of the liquid, and thus maximum heat and mass transfer capability , each orifice 227 is spaced a minimum distance from an inlet portion of each distribution tube 226, i.e., where the liquid enters the distribution tubes 226, as well as a minimum distance from each end portion of each distribution tube 226. As such, any potential turbulence of the liquid when flowing into and through the distribution tubes 226 can be limited and/or substantially eliminated. In this manner, substantially uniform flow of the liquid through each orifice 227 can be achieved.

[1039] The orifices 227 can also be sized to be large enough have a diameter (e.g., about 1/8") to prevent clogging by particles in the liquid (such as undissolved particles of the liquid desiccant salt). Additionally, although not shown, in some embodiments, the fluid treatment system 200 can include in the dispenser 220, and/or upstream to the dispenser 220 (in the stream of the liquid), any suitable type or number of filters configured to limit and/or prevent undesirable substances/particles in the liquid. In such embodiments, the orifices can be sized in accordance with the type and/or size of the filter(s). For example, if a 300 micron filter is installed upstream of the orifices, the orifices can have a diameter of at least 300 micron so as to not become clogged with any particles (e.g., a salt particle within the liquid) that passed through the 300 micron filter.

[1040] As can be seen in FIGs. 2, 3A and 3B, exchanger 210 can be configured with a set of lateral channels 214 in the top surface of exchanger 210, within which distribution tubes 226 can be received. This arrangement allows the gas inlet side of the extractor 230 to be disposed in abutting relationship with the gas outlet side of the exchanger 210, rather than having the two components of the system spaced apart to accommodate the distribution tubes 226 and/or other components of dispenser 220. Optionally, the lateral channels 214 can be sized so that the distribution tubes 226 are recessed below the gas outlet side of the exchanger, for example by a distance equal to or greater than the diameter of the distribution tubes. This arrangement causes the gas stream flowing around the distribution tubes 226 within the lateral channels 214 to be oriented towards the walls of lateral channels 214 downstream of the tubes, before it enters extractor 230. This ensuing change in direction of the air stream can aid in extraction (by adhesion to the surface of the channel walls) of any droplets entrained in the gas stream.

[1041] In this embodiment, extractor 230 is also implemented with blocks 232 of corrugated cellulose fiber sheets, which may be of the same construction as blocks 212 in exchanger 210. In this embodiment, extractor 230 is formed with two layers of blocks 232, with the blocks in the upper layer 236 oriented 90° from those in lower layer 234. Each layer of blocks thus changes the direction of the air stream flowing through the blocks, which causes the extraction of larger droplets or aerosols entrained by the air stream. More specifically, the air stream will be directed in a first direction in part by the lower layer 234 of the blocks 232, and then directed in a second direction, different than the first direction, in part by the upper layer 236 of the blocks 232. In this manner, the blocks 232 provide a tortuous path sufficient to remove droplets that are entrained by the air stream from the exchanger and/or the dispenser

[1042] In use, a liquid, such as a liquid desiccant, can flow from a liquid desiccant reservoir to the dispenser 220. The manifold 222 of the dispenser 220 can receive the liquid desiccant at the manifold inlet 223 and then convey the liquid desiccant to the distribution tubes 226 such that each distribution tube receives a substantially equal amount of liquid desiccant. From the distribution tubes 226 the liquid desiccant can be expelled through the orifices 227 to the exchanger 210 with suitable uniformity. The liquid desiccant can then flow along the surfaces of the flow channels in the blocks 212 (based on cohesive and gravitational forces). Concurrently, as best shown in FIGs. 3A and 3B, a gas stream (e.g., air) can enter the exchanger 210 via a gas inlet of the exchanger 210. The air stream can be passed through the exchanger 210, i.e., through the passages defined by the corrugations between the sheets of the blocks 212 (i.e. the matrix), counter to or across the liquid desiccant flow. In this manner, as the liquid desiccant flows through the matrix, the liquid desiccant is placed in fluid communication with the air stream, which in turn, can allow transfer of thermal energy and mass (e.g. water) from the air stream to the liquid desiccant. More specifically, when the liquid desiccant is placed in fluid communication with the air stream, having a higher partial pressure of water, at least a portion of the water content within the air stream is transferred to the liquid desiccant.

[1043] Further, as shown in FIGs. 7A and 7B, the air stream will pass through the matrix and downstream (in the stream of the air flow) of the dispenser, and subsequently reach the extractor 230, which in turn, will extract and/or collect any droplets or aerosols entrained by the air stream in the exchanger 210. In this manner, the untreated air stream entering the gas inlet of the exchanger 210 can be treated (dehumidified and/or cooled) within the exchanger 210 while minimizing formation of droplets or aerosols, and then further treated within the extractor 232 to remove any liquid droplets that are present in the air stream, such that carryover, if any, is negligible. With negligible carryover, and negligible loss of desiccant, corrosion of downstream components and replacement of desiccant can be substantially minimized.

[1044] EXAMPLES

[1045] A fluid treatment system similar to that illustrated in FIGs. 2-7B was tested to quantify the effectiveness of the system in eliminating carryover of liquid desiccant. In one test, direct measurement of carryover volume was made by capturing all particles above 0.1 micro-meters diameter using a very high efficiency filter, with a Minimum Efficiency Rating Value ("MERV") of 18. This test revealed carryover amounts below one part per trillion. This limit is more than 100 times lower than carryover detected in conventional designs.

[1046] In another test, ASTM B l 17 procedure (entitled "Standard Practice for Operating Salt Spray (Fog) Apparatus) was followed to prepare and dispose metallic test specimens downstream of the outlet side of the extractor of the fluid treatment system similar to that illustrated in FIGs. 2-7B. The test specimens were then evaluated for corrosion in accordance with International Standard ISO 9223 (1992) (Corrosion of metals and alloys - Corrosivity of Atmospheres - Classification" ("ISO 9223"), This testing revealed that the test system produced a treated air stream having a deposition rate of chloride "rate of chloride below 10 mg/m²d with greater than 98% confidence. According to Table 3 of ISO 9223, such a deposition rate of chloride is qualified in the "Si" category. Furthermore, according to Tables A.2 to A.4 of ISO 9223, a chloride deposition rate within the Si category, for an indoor, climatic controlled environment, regardless of sulfur dioxide levels, produces the lowest, or a negligible, corrosion rate as applied to aluminum, zinc, or copper, and according to Table Al of ISO 9223, this chloride deposition rate in this environment produces the lowest corrosion rate as applied to steel for all but the highest sulfur dioxide category. As most typical equipment downstream of a system such as that tested in this example contains aluminum, steel, zinc, and/or copper, the test reveals that using such a system would likely result in negligible corrosion. Even further, this is supported by direct microscopic and weight observations of corrosion levels over two months' time, which show negligible corrosion.

[1047] While various embodiments have been described above, it should be understood that they have been presented by way of example only, and not limitation. Where methods described above indicate certain events occurring in certain order, the ordering of certain events may be modified. Additionally, certain of the events may be performed concurrently in a parallel process when possible, as well as performed sequentially as described above. [1048] Where schematics and/or embodiments described above indicate certain components arranged in certain orientations or positions, the arrangement of components may be modified. Similarly, where methods and/or events described above indicate certain events and/or procedures occurring in certain order, the ordering of certain events and/or procedures may be modified. While the embodiments have been particularly shown and described, it will be understood that various changes in form and details may be made.

[1049] Although various embodiments have been described as having particular features and/or combinations of components, other embodiments are possible having a combination of any features and/or components from any of embodiments as discussed above.

Claims

What is claimed:

1. A system, comprising:

a dispenser coupleable to a source of a liquid and configured to convey the liquid from an inlet of the dispenser to an outlet of the dispenser;

a heat and mass exchanger disposed adjacent to the outlet of the dispenser and configured to receive the liquid discharged from the outlet of the dispenser; the heat and mass exchanger further configured to conduct a stream of a gas through the heat and mass exchanger between a gas inlet portion and a gas outlet portion of the heat and mass exchanger; the heat and mass exchanger further configured to treat the stream of the gas by contacting the stream of the gas with the liquid to transfer one or both of heat energy and water between the liquid and the gas to produce a treated stream of the gas at the gas outlet portion of the heat and mass exchanger;

an extractor having a gas inlet portion and a gas outlet portion, the gas inlet portion of the extractor disposed adjacent to the gas outlet portion of the heat and mass exchanger, the extractor configured to conduct the treated stream of the gas through the extractor between the gas inlet portion and gas outlet portion of the extractor, the extractor further configured to extract droplets of the liquid contained in the treated stream of the gas and to discharge from the outlet portion of the extractor the stream of the gas substantially devoid of droplets of the liquid.

2. The system of claim 1, wherein the liquid is a concentrated liquid desiccant, the gas is air containing water, and the heat and mass exchanger is configured to treat the stream of air to transfer water from the stream of air to the concentrated liquid desiccant, thereby dehumidifying the and diluting the liquid desiccant.

3. The system of claim 1, wherein the liquid is a concentrated liquid desiccant, the gas contains water, and the heat and mass exchanger is configured to treat the stream of gas to transfer water from the stream of gas to the concentrated liquid desiccant, thereby dehumidifying the gas and diluting the liquid desiccant.

4. The system of claim 1, wherein the extractor defines a tortuous path for the stream of gas between the gas inlet of the extractor and the gas outlet of the extractor, the tortuous path being sufficiently tortuous to prevent droplets of liquid above a predetermined size from remaining entrained in the gas stream flowing through the extractor

5. The system of claim I, further comprising a housing containing the heat and mass exchanger and at least a portion of the dispenser.

6. The system of claim I, wherein:

the outlet of the dispenser includes a plurality of tubes each having a plurality of orifices, each of which is configured to convey a portion of the liquid therethrough.

7. The system of claim 6, wherein:

the heat and mass exchanger includes a plurality of flow channels spaced at an approximately uniform spacing; and

the plurality of orifices are spaced at an approximately uniform spacing corresponding to the spacing of the flow channels.

8. The system of claim 6, wherein:

the heat and mass exchanger includes a plurality of lateral channels having a depth in the streamwise direction in which the gas flows through the heat and mass exchanger at least as large as the dimension of the plurality of tubes in the streamwise direction; and

each of the plurality of tubes is disposed in a respective one of the lateral channels.

9. The system of claim 6, wherein a flow rate of liquid sufficient to form and maintain a film of the liquid throughout the heat and mass exchanger can be conveyed through the dispenser and discharged from the orifices at a velocity below that at which the liquid would be dispensed in a spray and below that at which the liquid would splash on the surface of the heat and mass exchanger and produce droplets.

9. The system of claim 6, wherein a flow rate of liquid sufficient to form and maintain a film of the liquid throughout the heat and mass exchanger can be conveyed through the dispenser and discharged from the orifices at a pressure differential relative to the pressure of gas flowed through the heat and mass exchanger to prevent entry of the gas into the dispenser through the orifices.

10. The system of claim 6, wherein each of the orifices is sufficiently large to prevent obstruction by undissolved particles present in liquid desiccant.

11. The system of claim 1, wherein:

the extractor is configured to extract droplets having a size greater than a predetermined size.

12. The system of claim 8, wherein:

the dispenser and the heat and mass exchanger are configured to limit formation of droplets having a size of smaller than the predetermined size.

13. The system of claim 1, wherein:

the dispenser and the heat and mass exchanger are configured to convey the liquid through the gas while exchanging one or both of heat and water between the gas and the liquid without formation of droplets of the liquid having a size of smaller than a predetermined size.

14. The system of claim 1, wherein the heat and mass exchanger is formed of a material selected to allow adhesion of the liquid to the surface of the at a predetermined operative flow velocity of the gas through the heat and mass exchanger.

15. The system of claim 1, wherein the heat and mass exchanger is configured to conduct gas therethrough at a predetermined average gas flow velocity while maintaining the maximum gas flow velocity anywhere in the heat and mass exchanger below a velocity at which droplets of the liquid adhering to the surface of the heat and mass exchanger would form droplets entrained into the gas flow.

16. A method of operating the system of claim 6, comprising:

introducing into the gas inlet of the heat and mass exchanger a stream of gas having a gas flow rate;

introducing into the inlet of the dispenser from the source of liquid a flow rate of the liquid sufficiently large to form and maintain a film of the liquid throughout the heat and mass exchanger with the gas stream flowing over the liquid, the liquid neither spraying from the dispenser nor splashing against the surface of the heat and mass exchanger.