HEAT AND MASS TRANSFER ASSEMBLIES

The disclosure relates to heat and mass exchangers. In some examples, a heat-mass exchanger includes a plurality of regeneration fins extending generally vertically, and a plurality of desiccant feed tubes extending generally horizontally. The heat-mass exchanger also includes a plurality of regenerator heating tubes extending generally horizontally. The plurality of desiccant feed tubes are positioned above the plurality of regenerator heating tubes. In addition, the plurality of desiccant feed tubes and the plurality of regenerator heating tubes extend through the plurality of regeneration fins. Further, the plurality of desiccant feed tubes include feed tube openings adapted for delivering liquid desiccant onto surfaces of the plurality of regeneration fins.

TECHNICAL FIELD

The disclosure relates generally to heat and mass exchangers for heating, ventilation, and air conditioning systems and, more particularly, to heat and mass transfer assemblies for heat and mass exchangers.

BACKGROUND

Heating, ventilation, and air conditioning (HVAC) systems generally cool ambient or room temperature air using a vapor compression refrigeration cycle. The HVAC systems may cool the ambient or room temperature air by removing heat using a refrigerant. Less frequently, the HVAC systems may employ a liquid desiccant to dehumidify the air during the cooling process. Further, the HVAC systems may include a heat exchanger that operates to remove the heat from the refrigerant. For example, the heat exchanger may include plates or coils through which the refrigerant flows. A fan may blow air across the plates or coils to cool the refrigerant flowing within.

SUMMARY

According to some embodiments, a heat-mass exchanger includes a plurality of regeneration fins extending generally vertically, a plurality of desiccant feed tubes extending generally horizontally, and a plurality of regenerator heating tubes extending generally horizontally. The plurality of desiccant feed tubes and the plurality of regenerator heating tubes extend through the plurality of regeneration fins, where the plurality of desiccant feed tubes are positioned above the plurality of regenerator heating tubes. In addition, the plurality of desiccant feed tubes include feed tube openings adapted for delivering liquid desiccant onto surfaces of the plurality of regeneration fins.

DETAILED DESCRIPTION

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

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

Embodiments of the present disclosure relate generally to heat and mass exchangers and, more particularly, to heat and mass exchangers for liquid desiccant regeneration. For instance, in some examples, a heat and mass exchanger includes multiple regeneration fins (e.g., plates) extending along one direction (e.g., generally vertically). The heat and mass exchanger also includes multiple desiccant feed tubes that extend through the regeneration fins. The desiccant feed tubes can provide a flow of liquid desiccant (e.g., low concentration liquid desiccant) from, for instance, a conditioning system or a storage tank. Further, the heat and mass exchanger includes multiple regenerator heating tubes that also that extend through the regeneration fins. The regenerator heating tubes can provide a flow of heat transfer fluid (e.g., hot refrigerant from a vapor compression cycle loop or hot water from a waste heat recovery loop) e.g.. The desiccant feed tubes are positioned above the regenerator heating tubes as they extend through the regeneration fins.

Additionally, the desiccant feed tubes include feed tube openings (e.g., holes) adapted for delivering the liquid desiccant onto surfaces of the regeneration fins. For example, the liquid desiccant may proceed through the desiccant feed tubes and flow out of the desiccant feed tubes through the feed tube openings. As the liquid desiccant flows out of the feed tube openings, the liquid desiccant may flow down the surfaces of the regeneration fins. Heat may flow from the heat transfer fluid flowing through the regenerator heating tubes to the surface of the regeneration fins and then to the liquid desiccant, thereby evaporating water from the liquid desiccant and forming relatively higher concentration liquid desiccant. The liquid desiccant may be captured by a drain that is below the regeneration fins, and can be stored in a storage tank, for instance.

Referring to the drawings,FIG.1illustrates a heat-mass exchanger100that includes a plurality of regeneration fins108, as well as a plurality of desiccant feed tubes102and a plurality of regenerator heating tubes112that extend through the plurality of regeneration fins108. As illustrated, the plurality of regeneration fins108are positioned parallel to each other. In addition, in this example, the plurality of desiccant feed tubes102and the plurality of regenerator heating tubes112generally extend in a direction that is perpendicular to the direction in which the plurality of regeneration fins108extend. For instance, as illustrated, while the plurality of regeneration fins108generally extend generally in a vertical direction, the plurality of desiccant feed tubes102and the plurality of regenerator heating tubes112generally extend generally in a horizontal direction.

The plurality of regenerator heating tubes112may receive refrigerant105(e.g., hot refrigerant from a vapor compression cycle loop, such as hot refrigerant from a compressor of the vapor compression cycle loop), which flows through the plurality of regenerator heating tubes112as they extend through the plurality of regeneration fins108in a first direction. After proceeding across the plurality of regeneration fins108in the first direction113A, each of the plurality of regenerator heating tubes112may direct the refrigerant105back towards the plurality of regeneration fins108in a second direction113B that, in this example, is opposite the first direction113A. e.g. Heat may flow from the refrigerant105to the plurality of regeneration fins108as the refrigerant105flows through the plurality of regenerator heating tubes112, thereby removing heat from the refrigerant105. The refrigerant105may then be provided back to the vapor compression cycle loop (e.g., an expansion valve or subcooler of the vapor compression cycle loop).

In addition, each of the plurality of desiccant feed tubes102may receive liquid desiccant113(e.g., diluted liquid desiccant from a liquid desiccant air conditioning (LDAC) system or dehumidifier), and may feed the liquid desiccant113through one or more feed tube openings104. As the liquid desiccant113flows out from the feed tube openings104, the liquid desiccant113is delivered to surfaces109of the plurality of regeneration fins108. As such, the liquid desiccant113is distributed to regeneration channels127defined by adjacent regeneration fins108. As described above, heat may flow from the refrigerant105to the plurality of regeneration fins108. Heat may then flow from the plurality of regeneration fins108to the liquid desiccant113as the liquid desiccant113flows down the surfaces109, thereby causing water from the liquid desiccant113to evaporate and generate relatively more concentrated liquid desiccant111. A collector114may capture the concentrated liquid desiccant111which, as described further herein, can be provided to a storage tank.

Further, a regeneration airflow101may proceed counterflow (upward, in this example) to the liquid desiccant113proceeding along the surfaces109of the plurality of regeneration fins108. The regeneration airflow101may be provided by a fan or blower, for example. The regeneration airflow101may flow within the regeneration channels127(e.g., regeneration fin108gaps), thereby removing heat from the plurality of regeneration fins108and transferring water vapor away from the regenerating liquid desiccant.

In some examples, as described herein, the surfaces109of the plurality of regeneration fins108are lined with wicking material (e.g., as described below with respect toFIGS.4and6). The wicking material may be glued or bonded to the surfaces109, for instance. Further, the wicking material may be, for instance, a metal woven mesh, plastic woven material, plastic non-woven material, or cellulosic non-woven material, among other examples. In some examples, the surfaces109are hydrophilic. For example, the surfaces109may be etched, or may include hydrophilic coatings, ceramic slip coating, surface treatments, or micro-scale features or nano-scale features. In some examples, the surfaces109include stamped or embossed features.

In some examples, the heat-mass exchanger100includes a plurality of retention structures through which the plurality of desiccant feed tubes102extend (e.g., as described with respect toFIGS.2A,2B, and2C). The retention structures can include, for instance, O-rings, stamped features, or features coupled to a regeneration fin108. Each of the plurality of retention structures is adapted to create a liquid desiccant distribution reservoir. For instance, one or more retention structures may be positioned within the regeneration channels127defined by opposite facing surfaces109of adjacent regeneration fins108, and form a liquid desiccant distribution reservoir that can receive liquid desiccant113from one or more of the feed tube openings104of a corresponding desiccant feed tube102. After flowing into the liquid desiccant distribution reservoir, the liquid desiccant113may flow out of the liquid desiccant distribution reservoir and onto the surfaces109of the adjacent regeneration fins108. In some examples, as described herein, wicking material extends into the liquid desiccant distribution reservoir. A permeability of the wicking material allows the liquid desiccant113to flow out of the liquid desiccant distribution reservoir and onto the surfaces109of the adjacent regeneration fins108.

In some examples, the plurality of regeneration fins108include collars through which the plurality of desiccant feed tubes102extend. Each collar may be configured to receive liquid desiccant113from one or more feed tube openings104of a corresponding desiccant feed tube102. Further, the liquid desiccant113may flow from the collar and into a liquid desiccant distribution reservoir. For instance, each collar may include at least one collar opening, where the liquid desiccant113flows out of the collar openings and into the liquid desiccant distribution reservoir and/or the surfaces109of adjacent regeneration fins108.

The plurality of regeneration fins108may have a predetermined fin density, such as 3 to 12 regeneration fins108per inch. In addition, the plurality of regeneration fins108may be made from metal (e.g., aluminum) or metal alloy (e.g., aluminum alloy), for instance. The plurality of desiccant feed tubes102and the plurality of regenerator heating tubes112may be made from metal, metal alloy, or plastic (e.g., polyvinyl chloride (PVC)).

FIGS.2A,2B, and2Cillustrate exemplary details of the heat-mass exchanger100. As illustrated, a regeneration fin108includes a plurality of retention structures202through which a plurality of desiccant feed tubes102extend. For instance, each desiccant feed tube102may extend through an opening and a corresponding retention structure202of a regeneration fin108. Each retention structure202may be stamped, embossed, or otherwise coupled to the surface109of the regeneration fin108. The retention structures202may form a liquid desiccant distribution reservoir220for holding liquid desiccant113that is received from the feed tube openings104of a corresponding desiccant feed tube102.

Further, each regeneration fin108may include a feed tube collar204through which a corresponding desiccant feed tube102extends. The feed tube collars204may be part of, or coupled (e.g., attached) to, the regeneration fins108. Further, the feed tube collars204attach (e.g., secure) the desiccant feed tubes102to the regeneration fins108. The feed tube collars204may include one or more collar openings252, which may be aligned, at least partially, with a corresponding feed tube opening104of a desiccant feed tube102. Thus, liquid desiccant113may flow out from a desiccant feed tube102through a feed tube opening104and a corresponding collar opening252into a liquid desiccant distribution reservoir220defined, at least in part, by a retention structure202. As described herein, the liquid desiccant113may flow out of the liquid desiccant distribution reservoir220through wicking material (e.g., wicking material302) that may extend into the liquid desiccant distribution reservoir220.

The regeneration fins108may also include heating tube collars206through which the regenerator heating tubes112extend. The heating tube collars206may be part of, or coupled (e.g., attached) to, the regeneration fins108. Further, the heating tube collars206attach (e.g., secure) the regenerator heating tubes112to the regeneration fins108.

FIG.3illustrates desiccant feed tubes102extending through regeneration fins108, where the regeneration fins108are wavy in shape. The wavy shape of the regeneration fins108may increase a surface area109of the regeneration fins108, such as portions within the regeneration channels127, as well as increase the path length of the flowing air (e.g., regeneration airflow101). In addition, in this example, wicking material302(i.e., wicking media) is positioned along the surfaces109of the regeneration fins108. The wicking material302may be, for instance, a metal woven mesh, plastic woven material, plastic non-woven material, or cellulosic non-woven material, among other examples.FIG.4, for instance, illustrates a metal woven mesh400that may be adhered (e.g., glued, bonded) to a surface109of a regeneration fin108. Referring back toFIG.3, in some examples, the surfaces109of the regeneration fins108may, additionally or alternatively, include embossed or stamped features, which may increase surface109area, aid in liquid desiccant113wetting or break up regeneration airflow101boundary layers, or add turbulent mixing to the flowing air (e.g., regeneration airflow101). In some examples, the surfaces109may be coated with a hydrophilic material to promote spreading of the liquid desiccant113.

FIG.5illustrates a cross-sectional view of a heat-mass exchanger100that includes liquid desiccant distribution reservoirs220defined, at least in part, by O-rings504(e.g., rubber O-rings). In this example, wicking material302is positioned along the surfaces109of each regeneration fin108. Further, an O-ring504is positioned between opposite facing surfaces512of wicking material302. The liquid desiccant113proceeds through the desiccant feed tubes102, and exits out of a plurality of feed tube openings104that coincide with corresponding liquid desiccant distribution reservoirs220. Once in the liquid desiccant distribution reservoirs220, the liquid desiccant113may flow through portions of wicking material302that extend into the respective liquid desiccant distribution reservoirs220, and may continue to flow in a downwardly direction through the wicking material302, thereby contacting the surfaces109of the regeneration fins108.

FIG.6illustrates a heat-mass exchange system600that includes the heat-mass exchanger100. The heat-mass exchange system600further includes a LDAC system602, a liquid desiccant storage tank607, and a refrigerant based system612that includes or is part of a vapor compression cycle loop. The LDAC system602may receive high concentration liquid desiccant111from the liquid desiccant storage tank607to dehumidify a flow of process air. After being used to dehumidify the flow of process air, the LDAC system602provides lower concentration liquid desiccant113to the liquid desiccant storage tank607. The desiccant feed tubes102of the heat-mass exchanger100may receive the lower concentration liquid desiccant113from the liquid desiccant storage tank607. In addition, the regenerator heating tubes112of the heat-mass exchanger100may receive a flow of hot refrigerant105from the refrigerant based system612. Heat flows from the hot refrigerant as it flows through the regenerator heating tubes112, and the now cooler refrigerant105is provided back to the refrigerant based system612.

As described herein, the lower concentration liquid desiccant113may flow out of the desiccant feed tubes102through feed tube openings104, and may then flow down within regeneration channels127defined by adjacent regeneration fins108of the heat-mass exchanger100(e.g., along the surfaces109of the regeneration fins108). In addition, heat flows from the flow of hot refrigerant105, through the regenerator heating tubes112, and to the regeneration fins108. The heat then flows from the regeneration fins108to the liquid desiccant113flowing along its surfaces109, thereby evaporating water to generate relatively higher concentration liquid desiccant111(i.e., regenerating higher concentration liquid desiccant111from lower concentration liquid desiccant113).

In this example, the higher concentration liquid desiccant111flows through evaporative media605(e.g., CELdek®) before being captured by the collector114. The higher concentration liquid desiccant111may flow out of the collector114through a drain615, and is provided to the liquid desiccant storage tank607for use by the LDAC system602.

Among other advantages, the embodiments can provide a heat-mass exchanger that can regenerate liquid desiccant by heating low concentration liquid desiccant based on heat flowing from a hot heat transfer fluid, such as a hot refrigerant, to the low concentration liquid desiccant. For instance, in some examples, heat-mass exchanger includes a plurality of desiccant feed tubes and a plurality of regenerator heating tubes that extend through corresponding openings of a plurality of regeneration fins. The plurality of desiccant feed tubes are positioned above the plurality of regenerator heating tubes, and include feed tube openings that deliver liquid desiccant onto surfaces of the plurality of regeneration fins. For example, the plurality of desiccant feed tubes may receive low concentration liquid desiccant (e.g., used liquid desiccant) from a LDAC system, and may deliver the low concentration liquid desiccant to the feed tube openings.

Further, the low concentration liquid desiccant may flow out of the feed tube openings and into liquid desiccant reservoirs formed by retention structures on the surfaces of the plurality of regeneration fins. The low concentration liquid desiccant may flow out of the liquid desiccant reservoirs using wicking media that is aligned along the surfaces of the plurality of regeneration fins and extends into the liquid desiccant reservoirs. The liquid desiccant may then flow down through the wicking media and the surfaces of the plurality of regeneration fins. The plurality of regenerator heating tubes flow a hot refrigerant within (e.g., hot refrigerant received from a vapor compression cycle). Heat may flow from the hot refrigerant to the plurality of regenerator heating tubes, and then to the plurality of regeneration fins. As the liquid desiccant flows along the surfaces of the plurality of regeneration fins and the wicking media, heat flows to the liquid desiccant, thereby evaporating water and forming a relatively higher concentration liquid desiccant. A collector of the heat-mass exchanger may capture the higher concentration liquid desiccant, which may be provided to a storage tank for re-use by the LDAC system.