Three-way heat exchanger and heat exchanger

Abstract

The invention relates to a three-way heat exchanger and a heat exchanger. The three-way heat exchanger includes an airflow inlet, an airflow outlet, a heat transfer fluid inlet manifold extending proximate the airflow outlet, and a heat transfer fluid outlet manifold extending proximate the airflow outlet. The heat exchanger also includes panel assemblies each including a frame defining a heat transfer fluid passage and a membrane positioned on the frame and defining a desiccant passage. A heat transfer fluid passage is connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold for directing a flow of the heat transfer fluid between the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold against the airflow direction. Each panel assembly also includes a heat transfer fluid flow guide positioned in the heat transfer fluid channel to control a flow of the heat transfer fluid against the airflow direction.

Description

[0001] Cross - reference to related applications

[0002] This application claims the priority of Indian Patent Application No. 202311086763 filed on December 19, 2023 and U.S. Patent Application No. 18 / 585,344 filed on February 23, 2024, the entire disclosures of which are incorporated herein by reference. Technical field

[0003] The present disclosure generally relates to heating, ventilation, and air - conditioning (HVAC) systems, and more particularly to HVAC systems and methods including a three - way heat - exchange module for transferring heat between a heat - transfer fluid, a liquid desiccant, and air. Background art

[0004] Heating, ventilation, and air - conditioning (HVAC) systems are known for their ability to handle heating, cooling, and moisture removal of outside air circulated through indoor spaces. The vapor - compression cycle is widely used in HVAC systems to condition the temperature and humidity of outside air. Typically, outside air is cooled below its dew - point temperature to allow moisture in the air to condense on the evaporator coil, thereby dehumidifying the air. Since this process often results in the dehumidified air being at an uncomfortably low temperature, the air is then reheated to a more comfortable temperature for the user. The process of over - cooling and reheating the air can be very energy - consuming and expensive.

[0005] In some applications, HVAC systems include a vapor - compression system used in combination with a liquid - desiccant dehumidification system to remove moisture from outside air without cooling it below its dew - point temperature. For example, an HVAC system can include a refrigerant subsystem operating under a vapor - compression cycle and an air - handling subsystem that uses a heat - transfer fluid and a liquid desiccant to simultaneously absorb heat (sensible cooling) and moisture (latent cooling) from warm outside air to produce cooled and dehumidified indoor air. The air - handling subsystem can include a three - way heat - transfer device that facilitates sensible and latent cooling of warm outdoor air using a heat - transfer fluid and a liquid desiccant.

[0006] In the operation of a three-way heat exchanger, a liquid desiccant and a heat transfer fluid are directed through the heat exchanger, and heat is transferred between the liquid desiccant and the heat transfer fluid. An outdoor air stream is directed through the heat exchanger, and the heat transfer fluid absorbs heat from the air stream while the liquid desiccant absorbs moisture from the air stream. The liquid desiccant may be circulated between the three-way heat exchanger and a regeneration system, where the diluted liquid desiccant discharges the absorbed moisture into a sacrificial fluid. A refrigerant subsystem is engaged with the air handling subsystem, whereby the refrigerant absorbs heat from the heat transfer fluid in the three-way heat exchanger during the evaporation stage of the vapor compression cycle. The refrigerant is then directed to a condensation stage, in which the refrigerant discharges the absorbed heat into another fluid. The liquid desiccant processed by the regeneration system and the heat transfer fluid processed by the refrigerant subsystem are then directed back to the three-way heat exchanger to again provide sensible cooling and latent cooling of the outside air.

[0007] The three-way heat exchanger may include panels that direct the heat transfer fluid and the liquid desiccant through the three-way heat exchanger for absorbing heat and moisture from an air stream flowing between the panels. The heat transfer fluid and the liquid desiccant may flow freely through the panels and be distributed across respective flow channels in each panel. The free (e.g., uncontrolled) flow and distribution of the working fluid across the panels may result in very high temperature differences between the air stream and the fluid at local regions of the panels, and the very high temperature differences may negatively impact the performance of the heat exchanger. There is a need for a three-way heat exchanger that adequately controls the flow and / or distribution of the working fluid through the panels during operation of the heat exchanger. In particular, there is a need for a three-way heat exchanger that facilitates controlling the flow and distribution of the working fluid through the panels to provide a controlled temperature difference between the working fluid and the air stream across the panels.

[0008] This background section is intended to introduce to the reader various aspects of the art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to better understand the various aspects of the present disclosure. Accordingly, it is to be understood that these statements are to be read in this light and not as an admission of prior art. Summary of the Invention

[0009] One aspect is a three-way heat exchanger operable to transfer heat between a heat transfer fluid, a liquid desiccant, and air. The three-way heat exchanger includes an air flow inlet, an air flow outlet, a heat transfer fluid inlet manifold extending adjacent to the air flow outlet, and a heat transfer fluid outlet manifold extending adjacent to the air flow inlet. The three-way heat exchanger further includes a panel assembly arranged to have an air flow gap defined between adjacent panel assemblies to allow air to flow in an air flow direction between the air flow inlet and the air flow outlet. Each panel assembly includes a frame defining a heat transfer fluid passage. The heat transfer fluid passage is connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold for directing the flow of the heat transfer fluid between the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold against the air flow direction. Each panel assembly further includes: a membrane positioned on the frame and defining a desiccant passage for the flow of the liquid desiccant; and a heat transfer fluid flow guide positioned in the heat transfer fluid passage to control the flow of the heat transfer fluid against the air flow direction. The heat transfer fluid flow guide defines a heat transfer fluid flow path including a series of passages each extending across the air flow direction.

[0010] Another aspect is a three-way heat exchanger operable to transfer heat between a heat transfer fluid, a liquid desiccant, and air. The three-way heat exchanger includes a heat transfer fluid inlet manifold, a heat transfer fluid outlet manifold, and a panel assembly arranged to have an air flow gap defined between adjacent panel assemblies to allow air to flow through the three-way heat exchanger. Each panel assembly includes a frame defining a heat transfer fluid passage. The heat transfer fluid passage is connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold for directing the flow of the heat transfer fluid through the panel assembly. Each panel assembly further includes: two membranes positioned on the frame, each membrane defining a desiccant passage separate from the heat transfer fluid passage; and a heat transfer fluid flow guide positioned in the heat transfer fluid passage. The heat transfer fluid flow guide includes a sheet body and baffles. The baffles define a first flow path on one side of the sheet body and a second flow path on the other side of the sheet body. The first flow path and the second flow path are separated by the sheet body.

[0011] On the other hand, there is a heat exchanger that can be operated to transfer heat between a heat transfer fluid and air. The heat exchanger includes a heat transfer fluid inlet manifold, a heat transfer fluid outlet manifold, and a panel assembly. The panel assembly is arranged to have an air flow gap defined between adjacent panel assemblies to allow air to flow through the heat exchanger. Each panel assembly includes: a frame connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold; two plates positioned on the frame, the plates and the frame defining a heat transfer fluid passage for guiding the heat transfer fluid through the panel assembly; and a heat transfer fluid flow guide positioned in the heat transfer fluid passage. The heat transfer fluid flow guide includes: a sheet body; baffles located on the sheet body, the baffles defining a flow path for the heat transfer fluid in the heat transfer fluid passage; and protrusions located on the sheet body to maintain the height of the heat transfer fluid passage measured between the plates when the heat transfer fluid flows through the heat transfer fluid passage under negative pressure.

[0012] There are various improvements to the features pointed out in the above aspects. Other features can also be incorporated into the above aspects. These improvements and additional features can exist individually or in any combination. For example, each of the features discussed below with respect to any of the illustrated embodiments can be incorporated individually or in any combination into any one of the above aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 is a schematic flow chart of a heating, ventilation, and air conditioning (HVAC) system.

[0014] Figure 2 is included in Figure 1 the front perspective view of a three-way heat exchanger in an HVAC system.

[0015] Figure 3 is the front perspective view of a three-way heat exchanger, where various components are omitted to show the internal components.

[0016] Figure 4 is the rear perspective view of a three-way heat exchanger.

[0017] Figure 5 is the rear perspective view of a three-way heat exchanger, where similar to Figure 3 , various components are omitted.

[0018] Figure 6 is the left front view of a three-way heat exchanger, where similar to Figure 3 and Figure 5 , various components are omitted.

[0019] Figure 7 is included in Figures 2 to 6Right front view of an exemplary panel assembly in a three-way heat exchanger.

[0020] Figure 8 is Figure 7 Exploded view of the panel assembly.

[0021] Figure 9 is a schematic cross-section of the panel assembly taken along section line 9-9 in Figure 7

[0022] Figures 10A to 10D are respectively Figure 8 Enlarged views of portions A, B, C, and D shown in

[0023] Figure 11 is a schematic diagram showing the flow of liquid desiccant and heat transfer fluid through Figures 2 to 6 the three-way heat exchanger.

[0024] Figure 12 is Figure 7 Perspective view of the frame of the panel assembly and an exemplary flow guide.

[0025] Figure 13 Right front view of the frame and the flow guide.

[0026] Figure 14 Left front view of the frame and the flow guide.

[0027] Figure 15 Exploded view of the frame and the flow guide.

[0028] Figure 16A Perspective view of the independent flow guide.

[0029] Figures 16B to 16E Are various enlarged views of the parts of the flow guide.

[0030] Figure 17 is a schematic diagram showing Figure 7 the uncontrolled heat transfer fluid flow in the panel assembly.

[0031] Figure 18 is the time lapse of the thermal characteristics of the panel assembly during operation using the uncontrolled heat transfer fluid flow as shown in Figure 17

[0032] Figure 19 is a modeled comparison of the dew point temperature of the air flow (left figure) flowing between adjacent panel assemblies and the temperature of the uncontrolled heat transfer fluid flow (right figure) as shown in Figure 17

[0033] Figure 20 is a schematic diagram showing the use of Figures 12 to 1for the flow guide of 6 Figure 7 Schematic diagram of a controlled heat transfer fluid flow in a panel assembly of

[0034] Figure 21 shows the use of Figures 12 to 1 for the flow guide of 6 Figure 7 Another schematic diagram of a controlled and partially restricted heat transfer fluid flow in a panel assembly of

[0035] Figure 22 is in the example operation using a controlled heat transfer fluid flow such as Figure 20 or Figure 21 Time lapse of the thermal characteristics of the panel assembly in an example operation of a controlled heat transfer fluid flow as shown.

[0036] Figure 23 is the dew point temperature of the air flow (left figure) flowing between adjacent panel assemblies and the temperature (right figure) of a controlled heat transfer fluid flow such as Figure 20 or Figure 21 Modeling comparison as shown.

[0037] Throughout the figures, corresponding reference numerals indicate corresponding components. Detailed Description

[0038] Figure 1 is a schematic diagram of a heating, ventilation, and air conditioning (HVAC) system 100. The HVAC system 100 includes subsystems 102 to 106 and a liquid desiccant loop 108 that facilitate the heating, cooling, and moisture removal capabilities of the system 100. The subsystems of the HVAC system 100 include a refrigerant subsystem 102, a conditioner subsystem 104, and a regenerator subsystem 106. The conditioner subsystem 104 and the regenerator subsystem 106 can be used to process a first inlet air flow 110 and a second inlet air flow 114 respectively, and can be referred to herein as air handling subsystems 104 and 106. The HVAC system 100 may include additional components or other components in addition to those shown and described with reference to Figure 1 those shown and described.

[0039] In an example operating mode of the HVAC system 100, the conditioner subsystem 104 removes heat from the first inlet air flow 110 and directs the conditioned outlet air flow 112 to a conditioned space (not shown), such as the interior of a building structure or a vehicle. The conditioned outlet air flow 112 leaving the conditioner subsystem 104 may have a lower temperature than the first inlet air flow 110. The heat removed from the first inlet air flow 110 is transferred from the conditioning subsystem 104 to the refrigerant subsystem 102 and ultimately to the regenerator subsystem 106. The regenerator subsystem 106 transfers heat into the second inlet air flow 114 and directs the heated outlet air flow 116 to the atmosphere.

[0040] The refrigerant subsystem 102 includes an evaporator 118, a condenser 120, a compressor 122, and an expansion valve 124. The compressor 122 can be any suitable compressor, including but not limited to a scroll compressor, a reciprocating compressor, a rotary compressor, a screw compressor, and a centrifugal compressor. The expansion valve 124 can be any suitable expansion valve, such as a thermal expansion valve. The expansion valve 124 can alternatively be any suitable expansion device, such as an orifice or a capillary tube. The refrigerant subsystem 102 also includes a refrigerant loop 126 that circulates a working fluid, such as refrigerant, between the evaporator 118, the compressor 122, the condenser 120, and the expansion valve 124. The refrigerant subsystem 102 can include additional or other components in addition to those shown and described with reference to Figure 1 the components shown and described.

[0041] In an example operation of the refrigerant subsystem 102, the refrigerant in the loop 126 is directed as a low-pressure gas refrigerant 128 toward the compressor 122. The compressor 122 compresses the gas refrigerant 128, which increases the temperature and pressure of the refrigerant. The pressurized high-temperature gas refrigerant 130 exits the compressor 122 and is directed toward the condenser 120, where the high-pressure gas refrigerant 130 is condensed into a high-pressure liquid refrigerant 132. The liquid refrigerant 132 exiting the condenser 120 is directed toward the expansion valve 124, which reduces the pressure of the liquid. The depressurized fluid refrigerant 134, which can be a gas or a mixture of gas and liquid after passing through the expansion valve 124, is then directed toward the evaporator 118. The fluid refrigerant 134 evaporates into a gas in the evaporator 118, thereby exiting the evaporator as a low-pressure gas refrigerant 128. The gas refrigerant 128 is then directed back to the compressor 122, where the gas refrigerant 128 is compressed again and the process repeats. The circulation of the refrigerant in the loop 126 can be driven by the compressor 122, and more specifically, by the pressure difference that exists between the pressurized high-temperature gas refrigerant 130 exiting the compressor 122 and the low-pressure gas refrigerant 128 entering the compressor 122. As Figure 1 shown, the direction of flow of the refrigerant through the loop 126 can be reversed to switch the heat transfer functions of the evaporator 118 and the condenser 120, and enable the HVAC system 100 to operate in various operating modes.

[0042] The regulator subsystem 104 includes a first three-way heat exchanger 136 and a regulator heat transfer fluid loop 138 that circulates a regulator heat transfer fluid (e.g., water, an ethylene glycol-based fluid, or any combination of water and an ethylene glycol-based fluid) to and from the first three-way heat exchanger 136. The regulator subsystem 104 is engaged with the refrigerant subsystem 102 via the evaporator 118. In particular, the evaporator 118 is included in the refrigerant loop 126 and the regulator heat transfer loop 138 and facilitates the transfer of heat from the regulator heat transfer fluid in loop 138 to the fluid refrigerant 134 in the refrigerant loop 126. The regulator subsystem 104 may include additional or other components in addition to those shown and described with reference to Figure 1 the components shown and described. For example, the regulator subsystem 104 may include one or more pumps (not shown) that are configured to circulate the regulator heat transfer fluid in loop 138 between the first three-way heat exchanger 136 and the evaporator 118. Suitable pumps that may be included in the regulator subsystem 104 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. Depending on the operating requirements of the HVAC system 100 and other factors (e.g., the temperature and / or humidity of the first air inlet stream 110), the regulator subsystem 104 may include additional heat transfer devices that transfer heat from the regulator heat transfer fluid to the atmosphere or transfer heat from the atmosphere to the regulator heat transfer fluid.

[0043] In an example operation of the regulator subsystem 104, the regulator heat transfer fluid in loop 138 is directed towards the evaporator 118. The regulator heat transfer fluid is cooled in the evaporator 118 as heat is transferred from the regulator heat transfer fluid to the fluid refrigerant 134 in loop 126 to produce a gaseous refrigerant 128. The cooled regulator heat transfer fluid 140 exiting the evaporator 118 is directed towards and enters the first three-way heat exchanger 136. The first inlet air stream 110 is also directed through the first three-way heat exchanger 136. The first three-way heat exchanger 136 transfers heat from the first inlet air stream 110 to the regulator heat transfer fluid 140, thereby heating the regulator heat transfer fluid. The heated regulator heat transfer fluid 142 exiting the first three-way heat exchanger 136 is directed back to the evaporator 118, and the process is repeated.

[0044] The regenerator subsystem 106 includes a second three-way heat exchanger 144 and a regenerator heat transfer fluid loop 146 that circulates a regenerator heat transfer fluid (e.g., water, an ethylene glycol-based fluid, or any combination of water and an ethylene glycol-based fluid) to and from the second three-way heat exchanger 144. The regenerator subsystem 106 is engaged with the refrigerant subsystem 102 via the condenser 120. In particular, the condenser 120 is included in the refrigerant loop 126 and the regenerator heat transfer loop 146 and facilitates the transfer of heat from the pressurized gaseous refrigerant 130 in the refrigerant loop 126 to the regenerator heat transfer fluid. The regenerator subsystem 106 may include additional or other components in addition to those shown and described with reference to Figure 1 the components shown and described. For example, the regenerator subsystem 106 may include one or more pumps (not shown) that circulate the regenerator heat transfer fluid in loop 146 between the three-way heat exchanger 144 and the condenser 120. Suitable pumps that may be included in the regenerator subsystem 106 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. Depending on the operating requirements of the HVAC system 100 and other factors (e.g., the temperature and / or humidity of the first air inlet stream 110), the regenerator subsystem 106 may include additional heat transfer devices that transfer heat from the atmosphere to the regenerator heat transfer fluid or from the regenerator heat transfer fluid to the atmosphere.

[0045] In an example operation of the regenerator subsystem 106, the regenerator heat transfer fluid in loop 146 is directed toward the condenser 120. The regenerator heat transfer fluid is heated in the condenser as heat is transferred from the pressurized gaseous refrigerant 130 in loop 126 to the regenerator heat transfer fluid to produce a liquid refrigerant 132. The heated regenerator heat transfer fluid 148 exiting the condenser is directed toward and enters the second three-way heat exchanger 144. The second inlet air stream 114 is also directed through the second three-way heat exchanger 144. The second three-way heat exchanger 144 transfers heat from the regenerator heat transfer fluid to the second inlet air stream 114, thereby cooling the regenerator heat transfer fluid. The heated outlet air stream 116 exiting the second three-way heat exchanger 144 has a higher temperature than the second inlet air stream 114. The cooled regenerator heat transfer fluid 150 exiting the three-way heat exchanger 144 is directed back to the condenser 120, and the process is repeated.

[0046] The HVAC system 100 also includes a liquid desiccant loop 108 that operates in conjunction with subsystems 102 to 106 to condition a first inlet air stream 110 through latent heat cooling and sensible heat cooling. The liquid desiccant loop 108 includes a liquid desiccant that is routed between a first three-way heat exchanger 136 and a second three-way heat exchanger 144. Suitable liquid desiccants that may be used in the liquid desiccant loop 108 include, for example, desiccant salt solutions such as solutions of water and lithium chloride (LiCl), lithium bromide (LiBr), calcium chloride (CaCl2), or any combination thereof, triethylene glycol, sodium hydroxide, sulfuric acid, and so-called ionic liquid desiccants, or organic salts that are liquid at room temperature and have organic cations and organic or inorganic anions.

[0047] The liquid desiccant loop 108 may include one or more pumps (not shown) for routing the liquid desiccant between the first three-way heat exchanger 136 and the second three-way heat exchanger 144. Suitable pumps that may be included in the liquid desiccant loop 108 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. The liquid desiccant loop 108 may include one or more pumps for transferring the liquid desiccant from the second heat exchanger 144 towards the first heat exchanger 136, and one or more pumps for transferring the diluted liquid desiccant 154 from the first heat exchanger 136 towards the second heat exchanger 144.

[0048] The concentrated liquid desiccant 152 in the liquid desiccant loop 108 is routed towards the first three-way heat exchanger 136 of the conditioner subsystem 104, where the concentrated liquid desiccant 152 removes moisture from the first inlet air stream 110. The concentrated liquid desiccant 152 cooperates with the cooled conditioner heat transfer fluid 140 in the first three-way heat exchanger 136 to absorb heat and moisture from the first inlet air stream 110. The conditioned outlet air stream 112 exiting the first three-way heat exchanger 136 may have a lower humidity and / or a lower temperature compared to the first inlet air stream 110. The liquid desiccant that has absorbed moisture from the first inlet air stream 110 exits the first three-way heat exchanger 136 as the diluted liquid desiccant 154.

[0049] The diluted liquid desiccant 154 is directed towards the second three-way heat exchanger 144 of the regenerator subsystem 106, where the diluted liquid desiccant 154 discharges moisture into the second inlet air stream 114. The diluted liquid desiccant 154 cooperates with the heated regenerator heat transfer fluid 148 in the second three-way heat exchanger 144 to discharge heat and moisture into the second inlet air stream 114. Accordingly, the heated outlet air stream 116 exiting the second three-way heat exchanger 144 has a greater humidity and a higher temperature than the second inlet air stream 114. The liquid desiccant that has discharged moisture into the second inlet air stream 114 exits the regenerator subsystem 106 as the concentrated liquid desiccant 152. The concentrated liquid desiccant 152 exiting the second three-way heat exchanger 144 is directed back to the first three-way heat exchanger 136, and the process is repeated.

[0050] The liquid desiccant loop 108 may further include a desiccant-desiccant heat exchanger 156 that is configured to transfer heat from the concentrated liquid desiccant 152 that has exited the second three-way heat exchanger 144 to the diluted liquid desiccant 154 that has exited the first three-way heat exchanger 136. The desiccant-desiccant heat exchanger 156 may facilitate improving the functionality of the liquid desiccant in the three-way heat exchangers 136 and 144. For example, the desiccant-desiccant heat exchanger 156 may lower the temperature of the concentrated liquid desiccant 152 to provide greater cooling and dehumidification capabilities of the first three-way heat exchanger 136. Additionally and / or alternatively, the desiccant-desiccant heat exchanger 156 may increase the temperature of the diluted liquid desiccant 154 to enable the diluted liquid desiccant 154 to desorb a greater amount of moisture in the second three-way heat exchanger 144. The desiccant-desiccant heat exchanger 156 may be an in-line heat exchanger or any suitable heat exchanger that facilitates direct heat transfer between the concentrated liquid desiccant 152 and the diluted liquid desiccant 154. The desiccant-desiccant heat exchanger 156 may alternatively facilitate indirect heat exchange between the concentrated liquid desiccant 152 and the diluted liquid desiccant 154, such as indirect heat exchange via a vapor compression heat pump. In addition to or instead of the heat exchanger 156, auxiliary heating and cooling sources (e.g., heating and cooling fluids such as water) may be utilized to heat the diluted liquid desiccant 154 and cool the concentrated liquid desiccant 152, respectively. The liquid desiccant loop 108 may include additional or other components in addition to those shown and described with reference to Figure 1 those illustrated and described.

[0051] Thus, in an example mode of operation of the HVAC system 100, sensible cooling of the first inlet air stream 110 is facilitated by the first three-way heat exchanger 136 of the conditioner subsystem 104, which transfers heat from the inlet air stream 110 to the conditioner heat transfer fluid. The heat removed from the first inlet air stream 110 is then sequentially transferred between the subsystems 104, 102, and 106 via the evaporator 118 and the condenser 120 and is ultimately discharged into the second inlet air stream 114 via the second three-way heat exchanger 144. The first three-way heat exchanger 136 also facilitates latent cooling of the first inlet air stream 110 by removing moisture from the inlet air stream 110 using concentrated liquid desiccant 152. The moisture absorbed by the diluted liquid desiccant 154 is desorbed into the second inlet air stream 114 in the second three-way heat exchanger 144, which regenerates the concentrated liquid desiccant 152, and the concentrated liquid desiccant 152 is then directed back to the first three-way heat exchanger 136.

[0052] The HVAC system 100 can operate in addition to the above described with reference to Figure 1Operate in alternative operating modes other than the described exemplary operating modes. The exemplary operating modes of the HVAC system 100 described above can be considered as the warm weather operating mode of the HVAC system 100, in which the warm and humid air in the first inlet air stream 110 is cooled and dehumidified using the conditioner subsystem 104, and the heat and moisture removed are transferred by the subsystems 102 and 106 and the liquid desiccant loop 108 and discharged into the second inlet air stream 114 to produce a heated and humidified outlet air stream 116 that is directed to the warm and humid environment. In the cold weather operating mode of the HVAC system 100, the operation of the subsystems 102 to 106 and the liquid desiccant loop 108 can be reversed, such that the first three-way heat exchanger 136 heats and humidifies the cold and dry air in the first inlet air stream 110 to produce warm air with a comfortable humidity level in the outlet air stream 112 that is directed to the conditioned space. In the cold weather operating mode, the flow directions of the refrigerant in the loop 126 and the liquid desiccant in the liquid desiccant loop 108 can be reversed, such that the air handling subsystems 104 and 106 switch their respective functions, or the inlet and outlet vents for the first inlet air stream 110 and the second inlet air stream 114 can be rearranged and / or reconfigured such that the air flow directions through the first three-way heat exchanger 136 and the second three-way heat exchanger 144 are reversed, where the outlet air stream 112 is directed back to the surrounding environment and the outlet air stream 116 is directed towards the conditioned space. In other operating modes of the HVAC system 100, depending on the operating requirements and the desired set point temperature and humidity levels within the conditioned space, one of the air handling subsystems 104 and 106 can be idle or omitted from the HVAC system 100. For example, depending on the operating mode of the HVAC system 100, the air handling subsystem 106 can be omitted, and the refrigerant subsystem 104 can discharge or absorb heat from the refrigerant-air heat exchanger 120. In the case where the regenerator subsystem 106 is omitted or idle, the liquid desiccant circulating through the first three-way heat exchanger 136 in the liquid desiccant loop 108 can be regenerated or diluted using auxiliary regeneration equipment, dilution tanks, etc., depending on the operating mode of the HVAC system 100.

[0053] Still referring to Figure 1 , the first three-way heat exchanger 136 and the second three-way heat exchanger 144 have substantially the same configuration. In an alternative embodiment, the first three-way heat exchanger 136 and the second three-way heat exchanger 144 can have different configurations. Although the conditioner subsystem 104 and the regenerator subsystem 106 are in Figure 1are shown as including a three-way heat exchanger 136 and 144, respectively, but any suitable number of three-way heat exchangers 136 and 144 may be included in the respective subsystems 104 and 106. The number of three-way heat exchangers 136 included in the conditioner subsystem 104 may be the same as or different from the number of three-way heat exchangers 144 included in the regenerator subsystem 106. In the case where the conditioner subsystem 104 includes a plurality of three-way heat exchangers 136, the heat exchangers 136 may be operated in series, in parallel, or in any combination of series and parallel. In the case where the regenerator subsystem 106 includes a plurality of three-way heat exchangers 144, the heat exchangers 144 may be operated in series, in parallel, or in any combination of series and parallel.

[0054] Now referring to Figures 2 to 5 , an example three-way heat exchanger 200 for use in the air handling subsystem of the HVAC system 100 in Figure 1 will now be described. The three-way heat exchanger 200 may be implemented as the first three-way heat exchanger 136 in the conditioner subsystem 104 and / or the second three-way heat exchanger 144 in the regenerator subsystem 106. Figure 2 is a front perspective view of the three-way heat exchanger 200.

[0055] Figure 3 is a front perspective view of the three-way heat exchanger 200, in which various components are omitted to show the internal components of the three-way heat exchanger 200. Figure 4 is a rear perspective view of the three-way heat exchanger 200. Figure 5 is a rear perspective view of the three-way heat exchanger 200, in which, similar to Figure 3 , various components are omitted.

[0056] The three-way heat exchanger 200 has dimensions along the X-axis, Y-axis, and Z-axis, respectively. The X-axis, Y-axis, and Z-axis are perpendicular to each other. As described herein with respect to the three-way heat exchanger 200 and the components of the heat exchanger 200 during assembly, the dimension along the Z-axis may be referred to as the "height", the dimension along the Y-axis may be referred to as the "length", and the dimension along the X-axis may be referred to as the "width". The three-way heat exchanger 200 defines a lateral direction along the X-axis, a longitudinal direction along the Y-axis, and a vertical direction along the Z-axis. The X-axis may also be referred to as the lateral axis herein, the Y-axis may also be referred to as the longitudinal axis herein, and the Z-axis may also be referred to as the vertical axis herein. The three-way heat exchanger 200 has opposite first lateral sides 202 and second lateral sides 204, first longitudinal sides 206 and second longitudinal sides 208, and first vertical sides 210 and second vertical sides 212, respectively. The first lateral side 202 and the second lateral side 204 are spaced apart in the lateral direction, the first longitudinal side 206 and the second longitudinal side 208 are spaced apart in the longitudinal direction, and the first vertical side 210 and the second vertical side 212 are spaced apart in the vertical direction. The directional terms are only used to describe the spatial relationship of the three-way heat exchanger 200 and the components of the heat exchanger. The examples shown and described are not limited to any specific orientation.

[0057] The three-way heat exchanger 200 includes a set of panel assemblies 214 arranged continuously or in series in the lateral direction between the first lateral side 202 and the second lateral side 204. Each panel assembly 214 will be described in more detail below with reference to Figures 7 to 1 0. Each panel assembly 214 is in the form of a plate structure having internal heat transfer fluid channels through which heat transfer fluid, such as the conditioner heat transfer fluid in loop 138 or the regenerator heat transfer fluid in loop 146, flows. Each panel assembly 214 also includes liquid desiccant channels on opposite sides of the heat transfer fluid channels. Liquid desiccant, such as concentrated liquid desiccant 152 or diluted liquid desiccant 154 in the liquid desiccant loop 108, flows through the liquid desiccant channels. The liquid desiccant flowing through the liquid desiccant channels is separated from the heat transfer fluid flowing through the heat transfer fluid channels of the corresponding panel assembly, and heat exchange occurs between the liquid desiccant in the liquid desiccant channels and the heat transfer fluid flowing through the heat transfer fluid channels. An air flow gap 216, also referred to as an air gap 216, is defined in the lateral direction between adjacent panel assemblies 214. Each air flow gap 216 extends mainly in the vertical direction and the longitudinal direction.

[0058] Any suitable number of panel assemblies 214 may be included in the three-way heat exchanger 200. For example, the three-way heat exchanger 200 may include from 1 to 200 panel assemblies 214, from 1 to 100 panel assemblies 214, from 50 to 200 panel assemblies 214, from 50 to 100 panel assemblies 214, such as one panel assembly, ten panel assemblies 214, twenty panel assemblies 214, thirty panel assemblies 214, forty panel assemblies 214, fifty panel assemblies 214, sixty panel assemblies 214, seventy panel assemblies 214, eighty panel assemblies 214, ninety panel assemblies 214, 100 panel assemblies 214, or more than 100 panel assemblies 214.

[0059] The panel assemblies 214 are supported on a base 240 at a second vertical side 212 of the three-way heat exchanger 200. The panel assemblies 214 extend substantially parallel to each other between the base 240 and a first vertical side 210 of the three-way heat exchanger 200. In an example operation of the three-way heat exchanger 200, the panel assemblies 214 may deviate from a substantially parallel orientation when fluid flows through the panel assemblies 214 and / or when air flows through an air gap 216 between adjacent panel assemblies 214.

[0060] The three-way heat exchanger 200 includes a first end plate 218 and a second end plate 220 located at a first lateral side 202 and a second lateral side 204, respectively. The end plates 218, 220 may also be referred to as end caps or end sheets. The end plates 218 and 220 may provide lateral support for the set of panel assemblies 214 and enclose an interior 222 of the three-way heat exchanger 200 at the first lateral side 202 and the second lateral side 204. Figure 3 and Figure 5 The end plates 218 and 220 are omitted to more clearly show the arrangement of the panel assemblies 214, an air flow gap 216 defined between adjacent panel assemblies 214, and the interior 222 of the three-way heat exchanger 200.

[0061] Each of the end plates 218 and 220 includes alignment apertures 258 and 260, respectively, for receiving a clamping assembly (not shown) for clamping the panel assemblies 214 together. Example clamping assemblies suitable for use in the three-way heat exchanger 200 are described in U.S. Patent Application No. 18 / 490,984, filed on October 20, 2023, the entire disclosure of which is incorporated by reference.

[0062] The interior 222 of the three-way heat exchanger 200 can be enclosed by the set of panel assemblies 214 at the first vertical side portion 210 and the second vertical side portion 212 of the three-way heat exchanger. For example, adjacent panel assemblies 214 can be connected to and / or in contact with each other at opposite vertical ends to seal the respective air flow gaps 216 defined between adjacent panel assemblies at the opposite vertical ends and enclose the interior 222 of the three-way heat exchanger at the first vertical side portion 210 and the second vertical side portion 212. Additionally and / or alternatively, the three-way heat exchanger 200 can include vertical end plates (not shown) to enclose the interior 222 at the first vertical side portion 210 and the second vertical side portion 212.

[0063] The three-way heat exchanger 200 includes an air flow inlet 224 on the first longitudinal side portion 206 and an air flow outlet 226 on the second longitudinal side portion 208. The air flow inlet 224 and the air flow outlet 226 are defined by the longitudinal side panels 228 and 230 of the three-way heat exchanger 200, respectively. For example, the longitudinal side panels 228 and 230 can include openings in the form of grilles or grille openings, baffles, louvers, dampers, or can have any other suitable opening configuration to allow air flow to enter into and exit from the three-way heat exchanger 200. In some examples, one or both of the longitudinal side panels 228 and 230 can include a filter for filtering particles and / or contaminants from the air flow processed by the three-way heat exchanger 200. The air flow inlet 224 and the air flow outlet 226 communicate with the air flow gaps 216 defined between adjacent panel assemblies 214 and allow the inlet air flow (e.g., Figure 1 the first inlet air flow 110 or the second inlet air flow 114 in Figure 2 FIG.) to flow through the three-way heat exchanger 200 in the longitudinal direction (e.g., horizontally) along the air flow direction (indicated by the arrow 278 in Figure 3 and Figure 5 The longitudinal side panels 228 and 230 are omitted to more clearly show the arrangement of the panel assemblies 214, the air flow gaps 216 defined between adjacent panel assemblies 214, and the interior 222 of the three-way heat exchanger 200.

[0064] The three-way heat exchanger 200 further includes a heat transfer fluid inlet 232 and a heat transfer fluid outlet 234, as well as a liquid desiccant inlet 236 and a liquid desiccant outlet 238. The heat transfer fluid (e.g., in Figure 1circulate in one of the heat transfer fluid loops 138 or 146) enter and leave the three-way heat exchanger 200 via the heat transfer fluid inlet 232 and the heat transfer fluid outlet 234, respectively. Liquid desiccant (e.g., the liquid desiccant loop 108 in the circulation Figure 1 enters and leaves the three-way heat exchanger 200 via the liquid desiccant inlet 236 and the liquid desiccant outlet 238, respectively. The positions of the heat transfer fluid inlet 232, the heat transfer fluid outlet 234, the liquid desiccant inlet 236, and the liquid desiccant outlet 238 can vary according to the desired flow directions of the heat transfer fluid and the liquid desiccant through the panel assembly 214. The liquid desiccant inlet 236 and the heat transfer fluid outlet 234 can be defined (e.g., integrally formed therewith) by the end plate 218, and the liquid desiccant outlet 238 and the heat transfer fluid inlet 232 can be defined (e.g., integrally formed therewith) by the end plate 220. Alternatively, the heat transfer fluid inlet 232, the heat transfer fluid outlet 234, the liquid desiccant inlet 236, and the liquid desiccant outlet 238 can each be defined by a conduit (e.g., a pipe, a tube, a hose, or other suitable fluid conduit) that longitudinally extends through an opening in the respective end plates 218 and 220.

[0065] Referring to Figures 7 to 9 , an exemplary panel assembly 300 suitable for use as a separate panel assembly 214 will now be described. In the exemplary three-way heat exchanger 200, all the panel assemblies 214 have substantially the same configuration as the Figures 7 to 9 panel assembly 300 shown therein. For ease of description, the panel assembly 214 will be referred to hereinafter as the panel assembly 300. Some or all of the panel assemblies in the panel assembly 214 may include additional components, fewer components, or other components compared to the panel assembly 300.

[0066] Figure 7 is a right side view of the exemplary panel assembly 300. Figure 8 is an exploded view of the panel assembly 300. Figure 9 is along Figure 7 a schematic cross-section of the panel assembly 300 taken along the section line 9-9 in

[0067] The panel assembly 300 includes a frame 302 that defines a first vertical end 304 and a second vertical end 306 of the panel assembly 300 along the Z-axis, a first lateral face 305 and a second lateral face 307 along the X-axis, and a first longitudinal end 308 and a second longitudinal end 310 along the Y-axis. The frame 302 includes opposite first header sections 312 and second header sections 314 located at the first vertical end 304 and the second vertical end 306, respectively. The frame 302 further includes an intermediate section 316 between the opposite header sections 312 and 314. The header sections 312 and 314 define liquid desiccant header regions 320 and 322, respectively. The intermediate section 316 defines a heat transfer fluid region 324. The liquid desiccant header regions 320 and 322 are separated from the heat transfer fluid region 324 by portions of the frame 302 that extend between the heat transfer fluid region 324 and one of the liquid desiccant header regions 320 and 322, respectively.

[0068] The panel assembly 300 further includes a first plate 326 and a second plate 328 disposed on opposite lateral faces of the frame 302 that cover the intermediate section 316 of the frame 302. The first plate 326 and the second plate 328 are, for example, sheets of material less than 0.5 inches thick or less than 0.25 inches thick, and the plates 326, 328 may also be referred to as "heat exchange sheets" or "sheets". The first plate 326 and the second plate 328 may be attached to the frame 302 or may be integrally formed with the frame 302. Suitable techniques for attaching the plates 326 and 328 to the frame 302 may include, for example, welding (e.g., laser welding, induction welding, or radio frequency welding), adhesive bonding, thermal bonding, or another suitable technique for joining materials together. Additional details regarding attaching the plates 326 and 328 to the frame 302 are described, for example, in U.S. Patent No. 11,022,330, issued on June 1, 2021, and U.S. Patent No. 10,921,001, issued on February 16, 2021, the entire disclosures of which are incorporated herein by reference.

[0069] The frame 302 and the plates 326 and 328 can be made of different but compatible materials for welding together. For example, the frame 302 and the plates 326 and 328 can each be made of the same or different thermoplastic or polymeric materials. The materials for the frame 302 and the plates 326 and 328 can also be selected based on their compatibility with the liquid desiccant used in the three-way heat exchanger 200. Suitable polymeric materials for the frame 302 and the plates 326 and 328 include, for example, polyolefins (e.g., polypropylene and / or polyethylene), acrylonitrile butadiene styrene (ABS), and combinations thereof. The plates 326 and 328 can include additives that improve properties such as laser absorption and electrical conductivity, as well as the strength and / or stiffness of the plates 326 and 328. In other examples, the frame 302 and the plates 326 and 328 can be made of any other suitable materials that enable the three-way heat exchanger 200 to function as described.

[0070] The plates 326 and 328 encapsulate and seal the heat transfer fluid region 324 of the frame, thereby defining a heat transfer fluid passage 330 of the panel assembly 300 between the plates 326 and 328 (see Figure 9 ). As described below, in an example operation of the three-way heat exchanger 200, the heat transfer fluid flows through the heat transfer fluid passage 330 between the plates 326 and 328, and the liquid desiccant flows on the outer surfaces of the plates 326 and 328 opposite the heat transfer fluid passage 330. The plates 326 and 328 isolate the liquid desiccant from the heat transfer fluid in the passage 330 and allow heat to be transferred between the liquid desiccant and the heat transfer fluid. The plates 326 and 328 can extend over one or both of the liquid desiccant manifold regions 320 and 322 and define openings (e.g., orifices 360) that are aligned with one or both of the liquid desiccant manifold regions 320 and 322 to enable the liquid desiccant to flow therethrough. In an example panel assembly 300, each of the plates 326 and 328 includes a series of orifices 360 positioned adjacent to the liquid desiccant manifold 320 and a series of orifices 362 positioned adjacent to the liquid desiccant manifold region 322. The liquid desiccant can flow through the orifices 360 and 362 of each of the plates 326 and 328 to enter and / or leave the liquid desiccant manifold regions 320 and 322, respectively.

[0071] The flow guide 400 (e.g., as shown in Figure 12(shown in) may be positioned in the heat transfer fluid passage 330 to control the flow and / or distribution of the heat transfer fluid in the heat transfer fluid passage. The flow guide 400 may also maintain the width of the heat transfer fluid passage under a negative pressure, facilitate a constant flow of the heat transfer fluid through the passage 330, and / or provide turbulence of the heat transfer fluid to increase the heat transfer with the liquid desiccant and air flowing on the outer surfaces of the plates 326 and 328. The flow guide 400 is described in more detail below. A variety of materials may be used for the flow guide 400. For example, the flow guide 400 may include the same polymeric material as the plates (e.g., polyolefin, ABS, or a combination thereof). Additionally and / or alternatively, the flow guide 400 may include polyethylene terephthalate glycol (PETG).

[0072] Referring again to Figures 7 to 9 , the panel assembly 300 further includes membranes 332 and 334 disposed on opposite lateral faces 305 and 307 of the frame 302. In other examples, only one of the membranes 332 or 334 may be included in the panel assembly 300. The membranes 332 and 334 cover the outer surfaces of the plates 326 and 328. As Figure 9 shown, liquid desiccant channels 336 and 338 are defined between the membrane 332 and the plate 326 and between the membrane 334 and the plate 328, respectively. The membranes 332 and 334 also encapsulate and seal the liquid desiccant manifold regions 320 and 322. Each of the liquid desiccant channels 336 and 338 fluidly connects the liquid desiccant manifold regions 320 and 322. As described below, in an example operation of the three-way heat exchanger 200, the liquid desiccant flows through one of the liquid desiccant manifold regions 320 or 322, enters the liquid desiccant channels 336 and 338, above the outer surfaces of the plates 326 and 328 and behind the membranes 332 and 334, and finally enters the other of the liquid desiccant manifold regions 320 or 322. The plates 326 and 328 limit the contact between the liquid desiccant flowing in the liquid desiccant channels 336 and 338 and the heat transfer fluid flowing through the heat transfer fluid passage 330, and enable heat transfer therebetween. In an example where only one of the membranes 332 or 334 is included in the panel assembly 300, only one liquid desiccant channel 336 or 338 may be defined between the membrane 332 or 334 and the plate 326 or 328. In these examples, the plates 326 or 328 on the lateral faces 305 or 307 opposite the liquid desiccant channels 336 or 338 may encapsulate and seal the liquid desiccant manifold regions 320 and 322, and limit the flow of the liquid desiccant opposite the liquid desiccant channels 336 or 338.

[0073] Membranes 332 and 334 are respectively attached to one of the lateral surfaces 305 and 307 of the frame 302 to encapsulate and seal the liquid desiccant manifold regions 320 and 322. Membranes 332 and 334 can additionally and / or alternatively be attached to the outer surfaces of the respective plates 326 and 328, which can help maintain the width of the liquid desiccant channels 336 and 338 and / or limit the tendency of membranes 332 and 334 to bulge outward when liquid desiccant flows through the liquid desiccant channels 336 and 338. Membranes 332 and 334 can be attached to the lateral surfaces 305 and 307 of the frame 302 and / or the outer surfaces of the plates 326 and 328 using any suitable technique, such as, for example, adhesive bonding, heat sealing, or welding. Membranes 332 and 334 can be directly attached to plates 326 and 328 respectively by heat sealing or welding, where compatible materials (e.g., polyolefins) are used for membranes 332 and 334 and the respective plates 326 and 328. An outer adhesive layer (not shown) can be applied to the outer surfaces of plates 326 and 328 to improve the quality or ease of forming a heat seal or weld with the respective membranes 332 and 334. The outer surfaces of plates 326 and 328 can include raised patterns or dot features (not shown) to which membranes 332 and 334 adhere, heat seal, or otherwise attach. The raised patterns can be formed on the frame 302 and / or the plates 326 and 328 by thermoforming, embossing, or other suitable techniques. Attaching membranes 332 and 334 to the dot features or raised patterns can provide the additional advantage of promoting uniform distribution of the liquid desiccant across the liquid desiccant channels 336 and 338 in the longitudinal direction and reducing stresses that can cause warping of the plates 326 and 328. Warping of the plates 326 and 328 can reduce the ability to transfer heat and moisture between the heat transfer fluid, the liquid desiccant, and the air flowing through the membranes 332 and 334 in an example operation of the three-way heat exchanger 200. Additional details regarding attaching membranes 332 and 334 to the frame 302 and the respective plates 326 and 328 are described in U.S. Patent No. 11,022,330, issued June 1, 2021, and U.S. Patent No. 10,921,001, issued February 16, 2021, the entire disclosure of each of which is hereby incorporated by reference herein.

[0074] The membranes 332 and 334 are made of a vapor-permeable material that allows water vapor to pass therethrough such that the liquid desiccant flowing in the liquid desiccant channels 336 and 338 can absorb moisture from the air flowing through the membranes 332 and 334 and desorb water into the air flowing through the membranes 332 and 334. In some examples, the membranes 332 and 334 can each be made of a polypropylene material or other suitable vapor-permeable polymeric material. The vapor-permeable material for the membranes 332 and 334 can be microporous (e.g., having a pore size less than 0.5 micrometers (μm)). Examples of suitable microporous membranes are disclosed in U.S. Patent No. 9,101,874, which was published on August 11, 2015, and the entire disclosure of which is incorporated herein by reference. By way of example, suitable commercially available membranes include the EZ2090 polypropylene microporous membrane from Celgard. The microporous membranes 332 and 334 can have an open area of 40% to 80%, a pore size less than 0.5 μm, and a thickness less than 100 μm. Some example microporous membranes can have an open area greater than 80%. One suitable membrane has an open area of about 65% and a thickness of about 20 μm. The pore size of this type of membrane is very uniform structurally and is thin enough not to create a significant thermal barrier. Other possible membranes include those from 3M, Lydall, and other manufacturers. The membranes 332 and 334 can include any suitable vapor-permeable material that allows water to pass therethrough such that the liquid desiccant in the liquid desiccant channels 336 and 338 can absorb moisture from the air flowing over the membranes 332 and 334 or desorb water into the air flowing over the membranes 332 and 334.

[0075] The frame 302 defines a liquid desiccant inlet port 340 for supplying liquid desiccant into the liquid desiccant manifold region 320 and a liquid desiccant outlet port 342 for receiving liquid desiccant from the liquid desiccant manifold region 322. The liquid desiccant inlet port 340 is defined in the first corner flange 364 of the frame 302. The first corner flange 364 of the frame 302 is part of the first manifold section 312 and is positioned adjacent to the liquid desiccant manifold region 320 and the second longitudinal end 310 at the first vertical end 304 of the panel assembly 300. The liquid desiccant outlet port 342 is defined in the second corner flange 366 of the frame 302. The second corner flange 366 is part of the second manifold section 314 and is positioned adjacent to the liquid desiccant manifold region 322 and the first longitudinal end 308 at the second vertical end 306 of the panel assembly 300. Thus, the first corner flange 364 and the second corner flange 366 and the liquid desiccant inlet port 340 and the liquid desiccant outlet port 342 defined therein are located on opposite longitudinal and vertical ends of the panel assembly 300.

[0076] As represented by Figure 7 and Figure 9 the flow lines 344 in Figure 2 ), in an example operation of the three-way heat exchanger 200, liquid desiccant is supplied via the liquid desiccant inlet port 340 into the liquid desiccant manifold region 320 of the panel assembly 300, flows through each of the liquid desiccant channels 336 and 338 and into the liquid desiccant manifold region 322, and exits the panel assembly 300 via the liquid desiccant outlet port 342. In the illustrated example, the liquid desiccant flows vertically downward in the desiccant channels 336, 338. Thus, the liquid desiccant flows through the air flow direction 278 (or intersects the air flow direction 278)(

[0077] The frame 302 also defines a heat transfer fluid inlet port 346 for supplying heat transfer fluid to the heat transfer fluid passage 330 and a heat transfer fluid outlet port 348 for receiving heat transfer fluid from the heat transfer fluid passage 330. The heat transfer fluid inlet port 346 is defined in the third corner flange 368 of the frame 302. The third corner flange 368 of the frame 302 is part of the second header section 314 and the intermediate section 316. The third corner flange 368 is positioned adjacent to the heat transfer fluid passage 330 at the second longitudinal end 310 of the panel assembly 300 and near the second vertical end 306. The heat transfer fluid outlet port 348 is defined in the fourth corner flange 370 of the frame 302. The fourth corner flange 370 is part of the first header section 312 and the intermediate section 316. The fourth corner flange 370 is positioned adjacent to the heat transfer fluid passage 330 at the first longitudinal end 308 of the panel assembly 300 and near the first vertical end 304. Thus, the third corner flange 368 and the fourth corner flange 370 and the heat transfer fluid inlet port 346 and the heat transfer fluid outlet port 348 defined therein are located on opposite longitudinal ends and vertical ends of the panel assembly 300. Additionally, the first corner flange 364 and the fourth corner flange 370 and the liquid desiccant inlet port 340 and the heat transfer fluid outlet port 348 defined therein are all positioned near the first vertical end 304 on opposite longitudinal ends of the panel assembly. The second corner flange 366 and the third corner flange 368 and the liquid desiccant outlet port 342 and the heat transfer fluid inlet port 346 defined therein are all positioned near the second vertical end 306 on opposite longitudinal ends of the panel assembly.

[0078] As represented by Figure 7 and Figure 9 the flow line 350 in, in an example operation of the three-way heat exchanger 200, heat transfer fluid is supplied via the heat transfer fluid inlet port 346 to the heat transfer fluid passage 330 of the panel assembly 300, flows through it, and exits the panel assembly 300 via the heat transfer fluid outlet port 348. In the illustrated example, the heat transfer fluid flows vertically upward in the passage 330. Thus, the flow direction of the heat transfer fluid crosses (or intersects) the air flow direction 278 ( Figure 2)And is opposite (or in the opposite direction) to the flow of the liquid desiccant in channels 336 and 338. Since the heat transfer fluid inlet port 346 is located at the second longitudinal end 310 of the frame 302 and the heat transfer fluid outlet port 348 is located at the first longitudinal end 308, the heat transfer fluid also flows in a longitudinal direction opposite (or in the opposite direction) to the air flow direction 278. The heat transfer fluid can have an alternative flow direction. The flow direction of the heat transfer fluid in channel 330 can vary depending on, for example, the orientation of the panel assembly 300 in the heat exchanger 200, the positions of the heat transfer fluid inlet port 346 and the heat transfer fluid outlet port 348, and / or which ports 346, 348 the heat transfer fluid enters channel 330 through and which port the heat transfer fluid exits channel 330 through.

[0079] As further described below, the flow guide 400 (such as shown in Figure 12 ) can be positioned in the heat transfer fluid channel 330 to control the flow and / or distribution of the heat transfer fluid in the heat transfer fluid channel. The flow guide 400 can define one or more flow paths 402 that guide the heat transfer fluid as the heat transfer fluid flows through channel 330. The flow paths 402 can include a series of passages through which the heat transfer fluid flowing through channel 330 is redirected. For example, in the case where the heat transfer fluid flows vertically upward through channel 330 between ports 346, 348 as Figure 7 and Figure 9 illustrated, that is, across the air flow direction 278 and horizontally opposite to the air flow direction, the flow guide 400 can redirect the heat transfer fluid through the flow paths 402 to facilitate controlling the heat transfer fluid from reaching prematurely the region of the heat transfer fluid channel 330 near the first longitudinal end 308 of the frame 302. The flow paths 402 can include a series of passages that define a meandering path (e.g., a serpentine shape) such that the heat transfer fluid meanders (e.g., "snakes") through the heat transfer fluid channel 330 without reaching the first longitudinal end 308 prematurely. The flow guide 400 can also separate the flow paths 402 from a portion of the region of the heat transfer fluid channel 330 near the first longitudinal end 308 such that the heat transfer fluid is restricted or limited from flowing into those regions.

[0080] Figures 10A to 10D are respectively Figure 8 enlarged views of parts A, B, C, and D of the frame 302 shown in Figures 10A to 10DShows microchannels or orifices that provide fluid connections between ports 340, 342, 346, and 348 defined in panel assembly 300 and corresponding fluid regions. As Figure 10A and Figure 10B shown, the heat transfer fluid inlet port 346 is connected to the heat transfer fluid region 324 through orifice 352 ( Figure 10B ), and the heat transfer fluid outlet port 348 is connected to the heat transfer fluid region 324 through orifice 354 ( Figure 10A ). The heat transfer fluid region 324 defines a heat transfer fluid channel 330 when sealed to opposite lateral faces 305 and 307 of the frame 302 by plates 326 and 328. As indicated by the flow lines 350 in Figure 10A and Figure 10B , the heat transfer fluid enters the heat transfer fluid channel 330 from the inlet port 346 via orifice 352 and exits the channel 330 via orifice 354 into the outlet port 348.

[0081] As Figure 10C and Figure 10D shown, the liquid desiccant inlet port 340 is connected to the first liquid desiccant manifold region 320 through orifice 356 ( Figure 10C ), and the liquid desiccant outlet port 342 is connected to the second liquid desiccant manifold region 322 through orifice 358 ( Figure 10D ). As indicated by the flow lines 344 in Figure 10C and Figure 10D , the liquid desiccant enters the first liquid desiccant manifold region 320 from the inlet port 340 via orifice 356, flows into and through the liquid desiccant channels 336 and 338 ( Figure 9 ), enters the second liquid desiccant manifold region 322, and exits the manifold region 322 via orifice 358 into the outlet port 342. In the example illustrated in Figures 10A to 10D , each of the orifices 352 to 358 includes two orifices. Any suitable number of orifices can be used for orifices 352 to 358. In some examples, a greater number of orifices can be used for some of the orifices 352 to 358 than for other orifices 352 to 358. The number, size, and / or shape of orifices 352 to 358 can be the same or different. The number of orifices, as well as the size and shape, used for each of the orifices 352 to 358 can also vary between panel assemblies 300.

[0082] Figures 10A to 10DAlso shown are example features of the panel assembly 300 that can facilitate connecting adjacent panel assemblies 300 when the panel assembly is installed in the tee heat exchanger 200. For example, when the panel assemblies 300 are arranged in series and installed in the heat exchanger 200, the corner flanges 364 to 370 of the frames 302 of adjacent panel assemblies 300 can be connected. As shown, each of the corner flanges 364 to 370 includes one or more snap fittings 372. The snap fittings 372 extend in a lateral direction from the first lateral face 305 of the frame 302, and corresponding holes 374 ( Figure 6 shown) penetrate into the second lateral face 307 at a position laterally opposite to the snap fittings 372. In the illustrated example, each of the corner flanges 364 to 370 includes two snap fittings 372 and corresponding holes 374. In other examples, more or fewer snap fittings 372 and corresponding holes 374 may be included at the corner flanges 364 to 370. The corner flanges 364 to 370 may include the same or different numbers of snap fittings 372 and corresponding holes 374. Appropriately, for each snap fitting 372 in each of the corner flanges 364 to 370, a corresponding hole 374 is included. When the panel assemblies 300 are arranged in series and installed in the heat exchanger 200, each snap fitting 372 of the corner flanges 364 to 370 of the frame 302 of one of the panel assemblies 300 is received by one of the corresponding holes 374 of the corner flanges 364 to 370 of the frame 302 of the laterally adjacent panel assembly 300 to directly connect the adjacent panel assemblies 300.

[0083] Each of the corner flanges 364 to 370 also includes one or more alignment holes 376 extending therethrough in a lateral direction. In the illustrated embodiment, each of the corner flanges 364 to 370 includes two alignment holes 376, in Figures 10A to 10Dare marked as a first alignment hole 376a and a second alignment hole 376b. The first alignment hole 376a of each of the corner flanges 364 to 370 is longitudinally inside the second alignment hole 376b and adjacent to the corresponding corner of the heat transfer fluid region 324. In other examples, more or fewer alignment holes 376 may be included at the corner flanges 364 to 370. The corner flanges 364 to 370 may include the same or different numbers of alignment holes 376. When the panel assemblies are arranged in series and installed in the heat exchanger 200, the alignment holes 376 of the corner flanges 364 to 370 of the frame 302 of the panel assembly 300 receive corresponding clamping assemblies (not shown) for clamping the panel assemblies 300 together. The first alignment hole 376a of the panel assembly 300 corresponds to one of the alignment apertures 258 of the first end plate 218 and one of the alignment apertures 260 of the second end plate 220 ( Figure 2 and Figure 4 as shown). The second alignment hole 376b receives a corresponding clamping assembly (not shown). The second alignment hole 376b does not correspond to the alignment apertures 258 and 260 in the end plates 218 and 220, such that the clamping assembly received by the second alignment hole 376b extends through the panel assembly 300 but does not extend through the end plates 218 and 220.

[0084] Still referring to Figures 10A to 10D, each of the corner flanges 364 to 370 includes a flange collar 378 that surrounds a respective fluid port 340, 342, 346, 348 defined in the corner flange. The flange collar 378 extends in a lateral direction from a first lateral face 305 of the frame 302. Each of the corner flanges 364 to 370 also includes a corresponding slotted nozzle 380 that projects into the second lateral face 307 and surrounds the respective fluid ports 340, 342, 346, 348 at a position laterally opposite to the flange collar 378. When the panel assemblies 300 are arranged in series and installed in the heat exchanger 200, each flange collar 378 of the corner flanges 364 to 370 of the frame 302 of one of the panel assemblies 300 is received by one of the corresponding slotted nozzles 380 of the corner flanges 364 to 370 of the frame 302 of the laterally adjacent panel assembly 300 to directly connect the adjacent panel assemblies 300. Each flange collar 378 includes a set of guide teeth 382 that facilitate alignment of the flange collar 378 with the corresponding slotted nozzle 380 and insertion of the flange collar 378 into the slotted nozzle 380. The guide teeth 382 may include guiding features (e.g., chamfers) for easier insertion of the teeth and the flange collar 378 into the corresponding slotted nozzle 380. An elastomeric seal (not shown), such as an O-ring, may be seated within each of the slotted nozzles 380, and when the flange collar 378 is inserted into the slotted nozzle 380, a fluid-tight seal is formed at the adjacent fluid ports 340, 342, 346, 348 between the adjacent panel assemblies 300.

[0085] Also refer to Figure 3 and Figure 5 and similar to Figure 3 and Figure 5 left view of the three-way heat exchanger 200 with various components omitted Figure 6 , the panel assemblies 300 are arranged successively or in series in the lateral direction as described above. In Figure 3 , Figure 5 and Figure 6For ease of illustration, plates 326 and 328 and membranes 332 and 334 are omitted. When assembled and installed in the tee heat exchanger 200, for each pair of adjacent panel assemblies 300, the membrane 332 of one panel assembly in the panel assemblies 300 faces the membrane 334 of the other panel assembly in the panel assemblies 300. An air flow gap 216 is defined between the adjacent membranes 332 and 334. Each panel assembly 300 may have a reduced width at the intermediate section 316 such that the panel assemblies 300 are spaced apart at their adjacent intermediate sections 316 to define the air flow gap 216. Additionally and / or alternatively, the air flow gap 216 may be defined and maintained by supports or spacers 386 between the intermediate sections 316 of the adjacent panel assemblies 300. The supports or spacers 386 extend outwardly in the lateral direction from the intermediate sections 316 near the longitudinal ends 308 and 310. The intermediate section 316 of each frame 302 may additionally and / or alternatively include snap fittings 372 and corresponding holes 374 (as Figure 6 and Figure 7 shown) near the longitudinal ends 308 and 310. The snap fittings 372 and the corresponding holes 374 located on the intermediate section 316 of the frame 302 may facilitate connecting the adjacent panel assemblies 300 at the adjacent intermediate sections. In addition to the spacers 386, snap fittings 372 and corresponding holes 374 may also be included. Alternatively, in some examples, the spacer 386 may be a snap fitting 372 that engages the holes 374 of the adjacent panel assemblies 300 to connect the adjacent panel assemblies and maintain the width of the air flow gap 216.

[0086] The panel assemblies 300 are arranged in the tee heat exchanger 200 such that for each panel assembly, the first lateral face 305 and the second lateral face 307 of the frame 302 are respectively oriented towards the first lateral side 202 and the second lateral side 204 of the tee heat exchanger 200. The first longitudinal end 308 and the second longitudinal end 310 are respectively located at the first longitudinal side 206 and the second longitudinal side 208 of the tee heat exchanger 200, and the first vertical end 304 and the second vertical end 306 are respectively located at the first vertical side 210 and the second vertical side 212 of the tee heat exchanger 200.

[0087] The ports 340, 342, 346, and 348 of the panel assembly 300 are aligned to define respective manifolds of the three-way heat exchanger 200 that extend in a lateral direction, through which heat transfer fluid and liquid desiccant flow into and out of the panel assembly 300 between the first lateral side 202 and the second lateral side 204. The liquid desiccant inlet port 340 of the panel assembly 300 is aligned to form a liquid desiccant inlet manifold 242 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the first vertical side 210 and the second longitudinal side 208 of the three-way heat exchanger 200. The liquid desiccant outlet port 342 of the panel assembly 300 is aligned to form a liquid desiccant outlet manifold 244 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the second vertical side 212 and the first longitudinal side 206 of the three-way heat exchanger 200. The heat transfer fluid inlet port 346 of the panel assembly 300 is aligned to form a heat transfer fluid inlet manifold 246 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the second vertical side 212 and the second longitudinal side 208 of the three-way heat exchanger 200. The heat transfer fluid outlet port 348 of the panel assembly 300 is aligned to form a heat transfer fluid outlet manifold 248 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the first vertical side 210 and the first longitudinal side 206 of the three-way heat exchanger 200.

[0088] The panel assembly 300 may include an O-ring or other elastomeric sealing member that forms a fluid-tight seal between the aligned ports 340, 342, 346, and 348 of adjacent panel assemblies to prevent fluid leakage from the respective manifolds 242 to 248. For example, as described above, an elastomeric seal (not shown), such as an O-ring, may be seated within each of the grooved nozzles 380, and when the flange collar 378 is inserted into the grooved nozzle 380, a fluid-tight seal is formed at the adjacent fluid ports 340, 342, 346, 348 between adjacent panel assemblies 300. In some examples, the elastomeric seal 384 is a radial seal (e.g., a radial O-ring seal). Additionally, within each of the corner flanges 364 to 370, the snap fittings 372, corresponding holes 374, and alignment holes 376 together surround the fluid ports 340, 342, 346, 348 defined in the corner flanges, which may facilitate creating and maintaining a fluid-tight seal between the adjacent ports 340, 342, 346, 348 that define the manifolds 242 to 248.

[0089] As Figure 3 and Figure 5As shown, conduits 250, 252, 254, and 256 are used to fluidly connect the heat transfer fluid inlet 232 and the heat transfer fluid outlet 234, as well as the liquid desiccant inlet 236 and the liquid desiccant outlet 238, to corresponding manifolds for allowing the heat transfer fluid and the liquid desiccant to enter and exit the three-way heat exchanger 200. The liquid desiccant inlet 236 is fluidly connected to the liquid desiccant inlet manifold 242 via conduit 250. The liquid desiccant outlet 238 is fluidly connected to the liquid desiccant outlet manifold 244 via conduit 252. The heat transfer fluid inlet 232 is fluidly connected to the heat transfer fluid inlet manifold 246 via conduit 254. The heat transfer fluid outlet 234 is fluidly connected to the heat transfer fluid outlet manifold 248 via conduit 256. Conduits 250 through 256 can include any suitable fluid conduits (rigid and / or flexible) that enable the heat transfer fluid and the liquid desiccant to flow between the respective inlets and outlets and the manifolds, including, for example but not limited to, pipes, hoses, tubes, and combinations thereof. Each of conduits 250 through 256 can be attached to the respective manifolds 242 through 248 by coupling an end of the conduit to an appropriate one of the ports 340, 342, 346, and 348 in the end panel assembly 300 (i.e., the panel assembly 300 adjacent to the lateral sides 202 or 204). Conduits 250 through 256 can be attached to the appropriate ports 340, 342, 346, and 348 of the end panel assembly 300 using any suitable means - including fasteners, threads, clamps, etc.

[0090] Conduits 250 and 256 extend between the end plate 218 and the end panel assembly 300 at the first lateral side 202. Conduits 252 and 254 extend between the end plate 220 and the end panel assembly 300 at the second lateral side 204. Conduits 250 and 256 can extend through the end plate 218 to respectively define the inlet 236 or the outlet 234, can be coupled to the respective inlet 236 or outlet 234 defined by the end plate 218, or can be integrally formed with the end plate 218 and the respective inlet 236 or outlet 234 defined by the end plate 218. Conduits 252 and 254 can extend through the end plate 220 to respectively define the outlet 238 or the inlet 232, can be coupled to the respective outlet 238 or inlet 232 defined by the end plate 220, or can be integrally formed with the end plate 220 and the respective outlet 238 or inlet 232 defined by the end plate 220.

[0091] Each of the manifolds 242 to 248 may be closed at a lateral side 202 or 204 of the heat exchanger 200 opposite the inlet or outlet to which the manifold is connected. The liquid desiccant inlet manifold 242 may be closed at the second lateral side 204, the liquid desiccant outlet manifold 244 may be closed at the first lateral side 202 opposite the liquid desiccant inlet manifold 242, the heat transfer fluid inlet manifold 246 may be closed at the first lateral side 202, and the heat transfer fluid outlet manifold 248 may be closed at the second lateral side 204 opposite the heat transfer fluid inlet manifold 246. The manifolds 242 to 248 may be closed at the respective lateral sides 202 or 204 by end plates 218 or 220 ( Figure 2 and Figure 4 as shown). In particular, the end plate 218 may block the ports 342 and 346 of the panel assembly 300 at an end of the panel assembly 300 adjacent to the first lateral side 202 to close the manifolds 244 and 246 at the first lateral side 202. The end plate 220 may block the ports 340 and 348 of the panel assembly 300 at an end of the panel assembly 300 adjacent to the second lateral side 204 to close the manifolds 244 and 246 at the second lateral side 204. Additionally and / or alternatively, end caps or plugs 272 and 274 (see Figure 11 ) may be inserted into or otherwise disposed over the ports 342 and 346 of the panel assembly 300 adjacent to the first lateral side 202 to close the manifolds 244 and 246 at the first lateral side 202, and end caps or plugs 270 and 276 (see Figure 11 ) may be inserted into or otherwise disposed over the ports 340 and 348 of the panel assembly 300 adjacent to the second lateral side 204 to close the manifolds 244 and 246 at the second lateral side 204.

[0092] Now referring to Figure 11 , the operation of the three-way heat exchanger 200 will now be described. Figure 11 is a schematic view showing an internal view of the three-way heat exchanger 200 to depict the flow of liquid desiccant and heat transfer fluid through the manifolds 242 to 248 and the panel assembly 300. In the schematic view of Figure 11 , for ease of illustration and description, the panel assembly 300 is depicted as having exaggerated and / or simplified features.

[0093] In an example operation of the heat exchanger 200, an inlet air stream (e.g., Figure 1The first inlet air stream 110 or the second inlet air stream 114 (shown in ) enters via the air stream inlet 224 and flows along the air stream direction 278 through the air gap 216 defined between adjacent panel assemblies 300. The air flowing through the air gap 216 is directed to be treated by the liquid desiccant indicated by the flow line 344 and the heat transfer fluid indicated by the flow line 350 in each of the panel assemblies 300. In some operations, the liquid desiccant 344 is the concentrated liquid desiccant 152 from the liquid desiccant loop 108, and the heat transfer fluid 350 is the regulator heat transfer fluid from the Figure 1 regulator subsystem 104 shown in, and the heat exchanger 200 is used to cool and dehumidify the air flowing through the air gap 216. In other operations, the liquid desiccant 344 is the diluted liquid desiccant 154 from the liquid desiccant loop 108, and the heat transfer fluid 350 is from Figure 1 the regenerator heat transfer fluid of the regenerator subsystem 106 shown in, and the heat exchanger 200 is used to heat the moisture and discharge the moisture into the air flowing through the air gap 216.

[0094] The liquid desiccant 344 flows from the first side lateral portion 202 to the liquid desiccant inlet manifold 242 via the liquid desiccant inlet 236 and the conduit 250 ( Figures 3 to 5 shown). The liquid desiccant 344 enters the liquid desiccant header region 320 of each panel assembly 300 from the liquid desiccant inlet manifold 242 via the orifice 356. In each panel assembly 300, the liquid desiccant 344 flows from the liquid desiccant header region 320, enters the liquid desiccant channels 336 and 338 via the orifices 360 ( Figure 7 and Figure 8 shown) on each of the plates 326 and 328, flows downward through the liquid desiccant channels 336 and 338, and enters the liquid desiccant header region 322 via the orifices 362 ( Figure 7 and Figure 8 shown) on each of the plates 326 and 328. When the liquid desiccant 344 flows behind the membranes 332 and 334 of the panel assembly 300, the liquid desiccant 344 absorbs moisture from the air flowing through the air gap 216 adjacent to the membranes 332 and 334 or desorbs water into the air. Permitting moisture to permeate through each of the membranes 332 and 334 enables the transfer of moisture between the liquid desiccant 344 and the air in the air gap 216. The liquid desiccant 344 that has absorbed or desorbed moisture leaves each panel assembly 300 via the orifice 358 from the corresponding liquid desiccant header region 322 and flows toward the second side lateral portion 204 through the liquid desiccant outlet manifold 244. The liquid desiccant 344 flows via the conduit 252 and the liquid desiccant outlet 238 ( Figure 5as shown) exits the heat exchanger 200.

[0095] The heat transfer fluid 350 flows from the second lateral side 204 into the heat transfer fluid inlet manifold 246 via the heat transfer fluid inlet 232 and conduit 254 ( Figure 4 and Figure 5 as shown). The heat transfer fluid 350 enters each panel assembly 300 from the heat transfer fluid inlet manifold 246 via the orifice 352. In each panel assembly 300, the heat transfer fluid 350 flows upward through the heat transfer fluid channels 330. The heat transfer fluid 350 flowing through the channels 330 is in thermal communication with the liquid desiccant 344 flowing through the liquid desiccant channels 336 and 338. Depending on the operating mode of the heat exchanger 200, heat is transferred between the heat transfer fluid 350 and the liquid desiccant 344 to remove heat from the air flowing through the air gap 216 or discharge heat into the air flowing through the air gap 216. The heat transfer fluid 350 that has absorbed or discharged heat exits each panel assembly 300 via the orifice 354 and flows toward the first lateral side 202 through the heat transfer fluid outlet manifold 248. The heat transfer fluid 350 exits the heat exchanger 200 via the conduit 256 and the heat transfer fluid outlet 234 ( Figures 3 to 5 as shown).

[0096] In the illustrated embodiment, the flow directions of the heat transfer fluid 350 and the liquid desiccant 344 are shown by way of example only and may be varied in other embodiments of the heat exchanger 200. For example, the liquid desiccant 344 may flow upward through the desiccant channels 336 and 338 on the panel assembly 300. In these examples, the directions of flow of the liquid desiccant 344 through the liquid desiccant inlet 236 and the liquid desiccant outlet 238 and the liquid desiccant inlet manifold 242 and the liquid desiccant outlet manifold 244 will also be reversed. The heat transfer fluid 350 may flow downward through the heat transfer channels 330 of the panel assembly 300. In these examples, the directions of flow of the heat transfer fluid 350 through the heat transfer fluid inlet 232 and the heat transfer fluid outlet 234 and the heat transfer fluid inlet manifold 246 and the heat transfer fluid outlet manifold 248 will also be reversed. In the illustrated example, the liquid desiccant 344 and the heat transfer fluid 350 flow in a countercurrent relationship, but in alternative examples may flow in the same direction through the panel assembly.

[0097] Now referring to Figures 12 to 1 FIG. 6, one panel assembly, some panel assemblies, or all of the panel assemblies 300 may include flow guides 400 positioned in the heat transfer fluid channels 330 located between the plates 326, 328. Figure 12 is a perspective view of an example flow guide 400 shown positioned in the heat transfer fluid region 324 defined by the frame 302.Figure 13 and Figure 14 are the right and left front views of the frame 302 and the flow guide 400, respectively. Figure 15 is an exploded view of the frame 302 and the flow guide 400. Figure 16A is an isolated perspective view of the flow guide 400, and Figures 16B to 16E are various enlarged views of the various parts of the flow guide 400. When the panel assembly 300 is assembled and includes the flow guide 400, the plates 326 and 328 are attached to the frame 302 as described above such that the flow guide 400 is positioned within the heat transfer fluid passage 330 defined between the plates 326 and 328. The flow guide 400 defines one or more flow paths 402 (two flow paths 402a and 402b in the illustrated example), and the one or more flow paths 402 control the flow of heat transfer fluid through the heat transfer fluid passage 330, which will be described in more detail below. The flow guide 400 may be positioned within the heat transfer fluid region 324 without directly connecting or attaching the flow guide 400 to the frame 302. In this manner, during operation, the flow guide 400 is capable of “floating” within the heat transfer fluid flowing through the heat transfer fluid passage 330.

[0098] The flow guide 400 includes a body 404 formed as a panel or sheet. The body 404 may also be referred to as a sheet body 404. The sheet body 404 is made of a suitable structural material that enables the flow guide to function as described. In use, the flow guide 400 is immersed in a heat transfer fluid (e.g., water, ethylene glycol-based fluid, or any combination thereof) and may be suitably made of a polymeric material that provides structure to the sheet body 404 and facilitates limiting chemical interaction between the flow guide 400 and the heat transfer fluid. For example, the sheet body 404 may include PETG. Additionally and / or alternatively, the sheet body 404 may include the same polymeric material as the plates (e.g., polyolefin, ABS, or a combination thereof). The material used for the sheet body 404 may also be suitable for or facilitate forming the flow guide 400 as a single-piece unit, where the features of the flow guide 400 (e.g., the sheet body 404, the cutouts 406, the baffles 408, the restrictors 410, the alignment cutouts 416, the protrusions 418, and / or the pits 420) are integrally formed from one material. For example, the flow guide 400 may be made as a single-piece unit from a polymeric material such as PETG. The flow guide 400 may be made as a single-piece unit using, for example, vacuum forming or any other suitable thermoforming technique.

[0099] The sheet body 404 is sized and shaped to extend substantially across the heat transfer fluid region 324. In the illustrated example in which the two plates 326 and 328 and the two membranes 332 and 334 are attached to the lateral faces 305 and 307 of the frame 302, the sheet body 404 divides or separates the heat transfer fluid region 324 into a first heat transfer fluid region 324a( Figure 12 and Figure 13 ) and a second heat transfer fluid region 324b( Figure 14 ). When the plates 326 and 328 are attached to the frame 302, the first heat transfer fluid region 324a defines a first portion of the heat transfer fluid passage 330 between the sheet body 404 and the plate 326, and the second heat transfer fluid region 324b defines a second portion of the heat transfer fluid passage 330 between the sheet body 404 and the plate 328. The sheet body 404 may be substantially non-porous such that the sheet body 404 restricts or constrains the flow of the heat transfer fluid between the first and second portions of the heat transfer fluid passage 330. Alternatively, the sheet body 404 may include pores or other openings that allow the heat transfer fluid passage to flow between the first and second portions of the heat transfer fluid passage 330.

[0100] The sheet body 404 is sized, shaped, and positioned within the heat transfer fluid passage 330 such that the heat transfer fluid entering via the orifice 352( Figure 10B ) from the heat transfer fluid inlet port 346 can flow into both portions of the heat transfer fluid passage 330 and then exit from both portions of the heat transfer fluid passage 330 via the orifice 354( Figure 10A ) into the outlet port 348. In the illustrated example, the flow guide 400 includes two cutouts 406a and 406b that are defined at longitudinally and vertically opposite corners of the sheet body 404 relative to the orientation of the flow guide 400 when positioned within the heat transfer fluid region 324. Thus, when the flow guide 400 is positioned within the heat transfer fluid region 324, the first cutout 406a is located near the heat transfer fluid inlet port 346 and the second cutout 406b is located near the heat transfer fluid outlet port 348. The cutouts 406 define regions within the heat transfer fluid passage 330 that are not separated into separate portions by the sheet body 404. The heat transfer fluid entering the heat transfer fluid passage 330 from the inlet port 346 first flows into the region defined by the first cutout 406a. Then, the heat transfer fluid flows onto both sides of the flow guide 400 into both portions of the heat transfer fluid passage 330. The flow of the heat transfer fluid onto both sides of the flow guide 400 can be facilitated by alternating depressions 420 on the sheet body 404 that correspond to alternating protrusions 418 (e.g., Figure 16EAs shown), as further described below. The heat transfer fluid flows through two portions of the heat transfer fluid passage and is directed toward the second cutout 406b by the flow paths 402a and 402b on the two sides of the sheet body 404. The heat transfer fluid then flows into the region defined by the second cutout 406b and subsequently exits the heat transfer fluid passage 330 via the orifice 354 and enters the outlet port 348.

[0101] In the illustrated example, the flow guide 400 is used in the panel assembly 300, in which two plates 326 and 328 and two membranes 332 and 334 are attached to the lateral faces 305 and 307 of the frame 302. In this example, as described above, the sheet body 404 suitably divides or separates the heat transfer fluid region 324 into a first heat transfer fluid region 324a ( Figure 12 and Figure 13 ) and a second heat transfer fluid region 324b ( Figure 14 ), and defines the flow paths 402a and 402b in two portions of the heat transfer fluid passage 330. The heat transfer fluid in the flow path 402a can mainly exchange heat with the liquid desiccant flowing between the membrane 332 and the plate 326 and the air flow flowing near the membrane 332. The heat transfer fluid in the flow path 402b can mainly exchange heat with the liquid desiccant flowing between the membrane 334 and the plate 328 and the air flow flowing near the membrane 334. In other examples, some or all of the panel assemblies 300 may include one membrane (e.g., one of the membranes 332 or 334) and one desiccant passage 336 or 338. In such examples, the flow guide 400 may not need to divide the heat transfer fluid passage 330 into two portions, but the flow guide 400 may define a single flow path 402 adjacent to one of the desiccant passages 336 or 338 on one side of the sheet body 404.

[0102] The flow guide 400 further includes baffles 408 on two sides of the sheet body 404. The baffles 408 define by Figures 12 to 14The flow paths 402a and 402b indicated by the flow lines therein. Each of the flow paths 402a and 402b includes a series of passages in the heat transfer fluid channel 330. Adjacent passages are partially separated by baffles 408 and are connected end to end to form the flow paths 402a and 402b. The baffles 408 are operative to direct the heat transfer fluid 330 through the flow paths 402a and 402b. In the illustrated embodiment, each baffle 408 is located at complementary positions on two sides of the sheet body 404 such that the flow paths 402a and 402b are complementary to each other in the shape and number of passages. The baffle 408 and the sheet body 404 may be integrally formed of one material (e.g., a polymeric material such as PETG). The baffle 408 and the sheet body 404 may be integrally formed of one material using vacuum forming or other suitable thermoforming techniques. Referring to Figure 16C In the enlarged view of the illustrated flow guide 400, the baffle 408 has an "S-shaped" or "sinusoidal" profile such that each baffle 408 is located at complementary positions on two sides of the sheet body 404.

[0103] In the exemplary flow guide 400, two baffles 408 are located on each side of the sheet body 404, thereby defining three passages of the flow paths 402a and 402b. More or fewer baffles 408 may be included. The number of baffles 408 may vary depending on, for example, the desired number of channels of the flow paths 402a and 402b. The baffles 408 may be appropriately spaced apart depending on, for example, the number of baffles 408 and / or the desired size of each passage of the flow paths 402a and 402b. The baffles 408 may be arranged on the sheet body 404 such that the passages of the flow paths 402a and 402b may have the same or different sizes. When the flow guide 400 is positioned in the heat transfer fluid region 324, the baffle 408 may have any suitable orientation such that the flow guide 400 can function as described. For example, the position and orientation of the baffle 408 may vary depending on the desired shape of the flow paths 402a and 402b and the flow direction of the heat transfer fluid.

[0104] In the exemplary flow guide 400, each baffle 408 extends vertically on the sheet body 404 relative to the orientation of the flow guide 400 when positioned in the heat transfer fluid region 324. The baffles 408 are longitudinally spaced apart from each other, and the passages of the flow path 402a or 402b are defined on each side of each baffle 408. Each baffle 408 extends from one vertical end of the sheet body 404 and terminates before the other vertical end. The vertical ends of the sheet body 404 from which the baffles 408 extend alternate between adjacent baffles. Thus, the passages defined by the baffles 408 each extend vertically, and adjacent passages are horizontally connected in the longitudinal direction to form a meandering path (e.g.,Figures 12 to 14 the serpentine shapes of the flow paths 402a and 402b shown). The baffle 408 redirects the heat transfer fluid through the flow paths 402a and 402b such that the heat transfer fluid meanders or "snakes" through the heat transfer fluid channel 330, flowing in alternating vertical directions and ultimately flowing vertically upward and longitudinally between the heat transfer fluid inlet port 346 and the heat transfer fluid outlet port 348.

[0105] As described above, in an example operation of the three-way heat exchanger 200, the heat transfer fluid flows vertically through (or intersects) the air flow direction 278 in the heat transfer fluid channel 330 ( Figure 2 ) and flows longitudinally opposite (or longitudinally counter to) the air flow direction 278. The flow guide 400 facilitates controlling the premature arrival of the heat transfer fluid at the region of the first longitudinal end 308 of the heat transfer fluid channel 330 near the frame 302. Figure 17 is a schematic illustration of the free or "uncontrolled" flow of the heat transfer fluid in the heat transfer fluid channel 330 (represented by the flow line 350a), i.e., without the flow guide 400. As shown, when the heat transfer fluid 350a flows from the heat transfer fluid inlet port 346 to the heat transfer fluid outlet port 348, the free or uncontrolled flow of the heat transfer fluid 350a is horizontally (longitudinally) and vertically distributed across the heat transfer fluid channel 330. When uncontrolled, the heat transfer fluid 350a entering the heat transfer fluid channel 330 may initially tend to flow horizontally toward the first longitudinal end 308 of the frame 302 before flowing vertically upward toward the outlet port 348 near the first vertical end 304. An example of this tendency is shown in Figure 18 and is Figure 18 an example time-lapse of the thermal characteristics of the panel assembly 300 during operation without the flow guide 400, and Figure 18 shows cold heat transfer fluid initially flowing toward the first longitudinal end 308 of the panel assembly. Figure 18 The flow of the heat transfer fluid in

[0106] is from the lower left to the upper right of the panel assembly 300. When uncontrolled, the tendency of the heat transfer fluid to initially flow toward the first longitudinal end 308 may negatively impact the performance of the three-way heat exchanger 200 because this creates a situation in a local region of the panel assembly 300 (e.g., near the first longitudinal end 308 and the second vertical end 306) where there is an interaction between the heat transfer fluid 350a and the air flow (e.g., Figure 1a relatively high temperature difference is created between the first inlet air flow 110 or the second inlet air flow 114) therein. For example, a locally high temperature difference region of the panel assembly 300 may reduce the overall performance and / or efficiency of the three-way heat exchanger 200 because the heat transfer between the air flow and the heat transfer fluid is non-uniform across the panel assembly 300. Additionally, when the three-way heat exchanger 200 is used to condition hot, humid air, the relatively high temperature differences at these local regions may cause significant moisture condensation on the membranes 332, 334. Condensation may occur when the temperature within the three-way heat exchanger 200 is below the dew point temperature of the air flow passing therethrough. The likelihood of condensation can be estimated by comparing the temperature of the heat transfer fluid within the panel assembly 300 to the dew point temperature of the air flow passing through the air flow gap 216 - a dew point temperature significantly higher than the adjacent coolant temperature will indicate a high likelihood of condensation forming within the heat exchanger 200. Figure 19 is a modeled comparison of the dew point temperature of the air flow passing through the air flow gap 216 (left figure) and the temperature of the heat transfer fluid flowing freely or uncontrolled (without the flow guide 400) through the panel assembly 300 (right figure). As Figure 19 shown, there are local regions (where the uncontrolled heat transfer fluid has a tendency to flow horizontally against the air flow direction 278) near the bottom of the heat transfer fluid channels 330: at these regions, the temperature of the heat transfer fluid may be significantly lower than the dew point temperature of the air flow, thereby increasing the likelihood of condensation forming on the membranes 332, 334 adjacent to these regions. Such condensation on the membranes 332, 334 may negatively affect the performance of the heat exchanger 200, e.g., by reducing the effective mass transfer between the air flow and the liquid desiccant, restricting air flow, increasing the pressure drop through the air flow gap 216, and increasing the moisture accumulation within and around the panel assembly 300.

[0107] The flow guide 400 is operable to control the flow and / or distribution of the heat transfer fluid through the flow paths 402a and 402b in the heat transfer fluid channels 330 using the baffles 408, thereby preventing the heat transfer fluid from reaching prematurely the region of the first longitudinal end 308 of the channel 330 near the frame 302. Figure 20 is a schematic illustration of the "controlled" flow (represented by the flow line 350b) of the heat transfer fluid in the heat transfer fluid channels 330 using the flow guide 400, where the heat transfer fluid 350b flows through the flow channels 402a and 402b defined by the baffles 408 ( Figures 12 to 14)。As shown, as the heat transfer fluid 350b flows from the heat transfer fluid inlet port 346 to the outlet port 348, the controlled flow of the heat transfer fluid 350b meanders or snakes through the flow paths 402a and 402b, thereby passing through each vertical passage intersecting the air flow direction 278. The baffle 408 facilitates eliminating the tendency of the heat transfer fluid to initially flow horizontally toward the first longitudinal end 308 of the frame 302, which in turn eliminates the disadvantages of the uncontrolled heat transfer fluid flow described above with reference to Figures 17 to 19 The disadvantages of uncontrolled heat transfer fluid flow described above with reference to Figure 22 is an example of the elapsed time of the thermal characteristics of the panel assembly 300 during an exemplary operation when using the flow guide 400, and shows the controlled flow of the cold heat transfer fluid through the heat transfer fluid passage 330 (from the lower left to the upper right of the panel assembly). Compared with Figure 18 the thermal characteristics shown, Figure 22 the thermal characteristics in Figure 23 show that the flow guide 400 facilitates a more uniform distribution and well-controlled temperature difference between the air flow and the heat transfer fluid across the panel assembly 300. Figure 23 As shown, compared with Figure 19 when the flow of the heat transfer fluid is controlled as shown in Figure 20 the presence of local regions where the temperature of the heat transfer fluid is significantly lower than the dew point temperature of the air flow is greatly reduced or eliminated. Therefore, the flow guide 400 operates appropriately to significantly reduce the likelihood of condensation forming within the three-way heat exchanger 200.

[0108] Referring again to Figures 12 to 1 6, and additionally referring to the schematic diagram of Figure 21 , when the flow guide 400 is positioned in the heat transfer fluid region 324, the flow guide 400 may further include a flow restrictor 410, which is positioned on the sheet body 404 near the first longitudinal end 308. The flow restrictor 410 operates to constrict or limit the entry of the heat transfer fluid into the region of the heat transfer fluid passage 330 near the first longitudinal end 308. This "restricted region" is indicated by 412 in Figure 21 . Similar to the baffle 408, the flow restrictor 410 may be located at complementary positions on both sides of the sheet body 404, such that the flow restrictor 410 separates the flow path 402a from the restricted region 412a in the first part of the heat transfer fluid passage 330 ( Figure 12 and Figure 13 ) and separates the flow path 402b from the restricted region 412b in the second part of the heat transfer fluid passage 330 ( Figure 14)Separate. For example, the flow restrictor 410, the baffle 408, and the sheet body 404 can be integrally formed from a single material (e.g., a polymeric material such as PETG) using, for example, vacuum forming or another suitable thermoforming technique. The flow restrictor 410 can have an "S-shaped" or "sinusoidal waveform" profile similar to that of the Figure 16C illustrated baffle 408 such that the flow restrictor 410 is located at complementary positions on two sides of the sheet body 404.

[0109] In the exemplary flow guide 400, the flow restrictor 410 extends vertically and horizontally (longitudinally) on the sheet body 404 relative to the orientation of the flow guide 400 when positioned in the heat transfer fluid region 324. The flow restrictor 410 is longitudinally spaced from one of the baffles 408 and defines a passage for the flow path 402a or 402b therebetween. The flow restrictor 410 extends from one vertical end of the sheet body 404 near the second vertical end 306 of the frame 302 and vertically terminates before the other vertical end (near the outlet port 348) and extends horizontally toward the first longitudinal end 308 to define restricted regions 412a and 412b separate from the flow paths 402a and 402b. In the illustrated example, the flow restrictor 410 has an "L-shaped" configuration, but the flow restrictor can have other configurations such that the flow restrictor can function as described. When the heat transfer fluid (represented by the Figure 21 flow line 350c in) meanders or "snakes" through the flow paths 402a and 402b between the heat transfer fluid inlet port 346 and the heat transfer fluid outlet port 348, the flow restrictor 410 operates to prevent the heat transfer fluid from reaching the restricted regions 412a and 412b near the first longitudinal end 308 of the channel 330 adjacent the frame 302. Thus, the flow restrictor 410 can further prevent condensation with the three-way heat exchanger 200 by reducing or eliminating the presence of local regions where the temperature of the heat transfer fluid is significantly below the dew point temperature of the air stream.

[0110] The flow guide 400 can be sized such that a gap 414 is defined between the top vertical end of the sheet body 404 and the topmost portion of the heat transfer fluid channel 330 when the flow guide 400 is positioned therein (in Figure 13 , Figure 20 and Figure 21as shown). A gap 414 is defined above one or more baffles 408 located at the vertical ends of the sheet body 404, and the gap is connected to one or more of the passages of the flow paths 402a and 402b. The heat transfer fluid may include entrained air bubbles that limit or impede the vertical downward flow of the heat transfer fluid in the flow paths 402a and 402b. The gap 414 facilitates the capture of entrained air from the flow of the heat transfer fluid, allowing the air to pass therethrough while the heat transfer fluid is vertically downwardly directed through the connecting passages of the flow paths 402a and 402b. Suitably, the gap 414 is sized to capture entrained air while restricting or preventing the heat transfer fluid from flowing therethrough and bypassing the connecting passages of the flow paths 402a and 402b.

[0111] As described above, the flow guide 400 may be positioned within the heat transfer fluid region 324 of the frame 302 without directly attaching the flow guide to the frame, such that the flow guide is capable of floating in the heat transfer fluid channel 330. Suitably, the flow guide 400 includes one or more alignment features 416 that are complementary to corresponding alignment features 388 of the frame 302 for positioning and orienting the flow guide 400 within the heat transfer fluid region 324. The corresponding alignment features 388 and 416 can ensure that the baffles 408 and restrictors 410 are properly oriented to function as described. In Figures 12 to 1 the illustrated example of FIG. 6, the sheet body 404 includes alignment notches 416 that are complementary to alignment protrusions 388 located on the frame 302. The alignment protrusions 388 extend longitudinally into the heat transfer fluid region 324 near the first longitudinal end 308 and are received by the alignment notches 416 of the flow guide 400 when properly positioned and oriented. In other examples, the alignment features 388 and 416 can have any suitable positions on the frame 302 and the flow guide 400, respectively, to facilitate positioning and orienting the flow guide within the heat transfer fluid region 324.

[0112] Referring to FIG. 16, the flow guide 400 also includes protrusions 418 on two sides of the sheet body 404. The protrusions 418 and the sheet body 404 (and the baffles 408 and / or restrictors 410) can be integrally formed from one material (e.g., a polymeric material such as PETG). For example, the protrusions 418 and the sheet body 404 can be integrally formed from one material using vacuum forming or another suitable thermoforming technique. Each protrusion 418 on one side of the sheet body 404 has a corresponding pit 420 located on the other side of the sheet body. The protrusions 418 are arranged such that each side of the sheet body 404 has alternating protrusions 418 and pits 420.

[0113] In an example operation of the three-way heat exchanger 200, the flow rate of the heat transfer fluid can be such that the heat transfer fluid passage 330 is under a negative pressure (e.g., below atmospheric pressure). This can create an opportunity for the plates 326, 328 to "collapse" inwardly, which restricts or impedes the flow of the heat transfer fluid through the panel assembly 300. The protrusions 418 extend from the sheet body 404 by a suitable width to facilitate maintaining the width of the heat transfer fluid passage 330 measured between the plates 326, 328. In particular, when the heat transfer fluid flows through the heat transfer fluid passage under a negative pressure (e.g., below atmospheric pressure), the protrusions 418 facilitate maintaining the width of the heat transfer fluid passage 330 by reducing or eliminating the tendency of the plates 326, 328 to collapse inwardly. The protrusions 418 and the corresponding pits 420 can additionally and / or alternatively promote a constant flow of the heat transfer fluid through the passage 330 and / or provide turbulence of the heat transfer fluid to increase heat transfer with the liquid desiccant and the air flowing over the outer surfaces of the plates 326 and 328.

[0114] As Figure 16E shown in the enlarged view of, when the flow guide is positioned in the heat transfer fluid passage 330, the first cutout 406a positioned adjacent to the inlet port 346 of the flow guide 400 can be located on the sheet body 404 such that some of the protrusions 418 and the pits 420 are partially cut off. The first cutout 406a and the cut-off protrusions 418 and pits 420 can form a suitable profile of the sheet body 404 at the first cutout 406a to guide the heat transfer fluid entering the heat transfer fluid passage 330 to flow on each side of the sheet body 404. In particular, the cut-off protrusions 418 and pits 420 can define discrete inlets on two sides of the flow guide 400, and the discrete inlets are for the heat transfer fluid entering the heat transfer fluid passage 330 from the inlet port 346 to flow into two portions of the heat transfer fluid passage 330.

[0115] The described example HVAC system includes one or more three-way heat exchangers for removing heat and moisture from an air stream and / or discharging heat and moisture into the air stream. Example three-way heat exchangers include panel assemblies arranged in series and defining an air gap for air to flow therebetween. A heat transfer fluid and a liquid desiccant are directed through manifolds to each panel assembly to treat the air flowing through the air gap. The operating efficiency and life of the three-way heat exchanger are improved by flow guides positioned in the heat transfer fluid channels of one, some, or all of the panel assemblies. The flow guides facilitate controlling the flow and / or distribution of the heat transfer fluid directed through the panel assemblies. The flow guides can direct the heat transfer fluid to flow along a controlled flow path that prevents the heat transfer fluid from reaching prematurely regions of the heat transfer fluid channels where there might otherwise be a significant temperature difference between the heat transfer fluid and the air. This facilitates reducing the tendency for heat transfer to concentrate in localized regions of the panel assemblies, which could reduce the overall performance and / or efficiency of the three-way heat exchanger. Additionally and / or alternatively, the controlled flow of the heat transfer fluid facilitated by the flow guides can reduce or eliminate the tendency for large amounts of moisture to condense within the heat exchanger, which would otherwise have a negative impact on the performance and / or efficiency of the heat exchanger. Additional technical benefits that can be provided by the flow guides include, but are not limited to, maintaining the width of the heat transfer fluid channels under negative pressure, facilitating a constant flow rate of the heat transfer fluid through the panel assemblies, providing turbulence of the heat transfer fluid to increase heat transfer with the liquid desiccant and the air, and / or improving the manufacturability of the flow guides that can be made as a single-piece unit from a single material.

[0116] Example embodiments of the HVAC system and methods of operating the system have been described in detail above. The system and methods are not limited to the specific embodiments described herein. Instead, components of the system and methods can be used independently and separately from other components described herein. For example, the system described herein can be used in systems other than HVAC systems.

[0117] When introducing elements of the present disclosure or embodiments of the present disclosure, the articles “a,” “an,” “the,” and “said” are intended to mean that there is one or more of the elements. The terms “comprising,” “including,” “containing,” and “having” are intended to be inclusive and mean that there may be additional elements in addition to the listed elements. The use of terms indicating a particular orientation (e.g., “top,” “bottom,” “side,” “vertical,” “lateral,” “longitudinal,” etc.) is for convenience of description and does not require any particular orientation of the items described.

[0118] The terms "about", "substantially", "essentially" and "approximately" and their equivalents, when used in connection with ranges of dimensions, concentrations, temperatures or other physical or chemical properties or characteristics, are meant to cover variations that may exist in the upper and / or lower limits of the range of the properties or characteristics, including, for example, variations resulting from rounding, measurement methods or other statistical variations.

[0119] Since various changes may be made to the above-described construction and method without departing from the scope of the present disclosure, all matter contained in the above description and shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense.

Claims

1. A three-way heat exchanger operable to transfer heat between a heat transfer fluid, a liquid desiccant and air, the three-way heat exchanger comprising: an air flow inlet and an air flow outlet; a heat transfer fluid inlet manifold extending proximate the airflow outlet and a heat transfer fluid outlet manifold extending proximate the airflow inlet; as well as The panel assemblies are arranged with airflow gaps defined between adjacent panel assemblies to allow air to flow between the airflow inlet and the airflow outlet in an airflow direction, each panel assembly comprising: a frame defining a heat transfer fluid passage connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold for directing the flow of the heat transfer fluid between the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold against the direction of the air flow; a membrane positioned on the frame and defining a desiccant channel for flow of the liquid desiccant; and A heat transfer fluid flow guide is positioned in the heat transfer fluid channel to control the flow of the heat transfer fluid against the air flow direction, the heat transfer fluid flow guide defines a heat transfer fluid flow path, and the heat transfer fluid flow path includes a series of passages, each passage extending across the air flow direction.

2. The three-way heat exchanger according to claim 1, wherein: The heat transfer fluid flow guide includes a sheet body and a baffle located on the sheet body, wherein the baffle defines the heat transfer fluid flow path.

3. The three-way heat exchanger according to claim 2, wherein: The baffle is located on both sides of the sheet body, and defines a first heat transfer fluid flow path on one side of the sheet body and a second heat transfer fluid flow path on the other side of the sheet body.

4. The three-way heat exchanger according to claim 3, wherein: The first heat transfer fluid flow path and the second heat transfer fluid flow path are complementary, and wherein the heat transfer fluid flow paths each define a serpentine path.

5. The three-way heat exchanger according to claim 3, wherein: Each panel assembly includes two membranes, each membrane is positioned on a side of the frame, wherein one membrane defines a first desiccant channel and the other membrane defines a second desiccant channel, wherein the first heat transfer fluid flow path is defined between the sheet body and the first desiccant channel, and the second heat transfer fluid flow path is defined between the sheet body and the second desiccant channel.

6. The three-way heat exchanger according to claim 5, wherein: Each panel assembly includes two plates, each plate positioned between one of the membranes and the frame, wherein the plates separate the desiccant channels from the heat transfer fluid channels.

7. The three-way heat exchanger according to claim 6, wherein: The heat transfer fluid flow guide includes a protrusion located on the sheet body to maintain a width of the heat transfer fluid channel measured between the plates when the heat transfer fluid flows through the heat transfer fluid channel under negative pressure.

8. The three-way heat exchanger according to claim 1, wherein: The air flow direction is horizontal, and the passages of the heat transfer fluid flow path each extend vertically across the air flow direction.

9. The three-way heat exchanger according to claim 8, wherein: A gap is defined in the heat transfer fluid channel above the heat transfer fluid flow guide, the gap connected to one or more of the passages of the heat transfer fluid flow path to capture entrained air from the flow of the heat transfer fluid.

10. The three-way heat exchanger according to claim 1, wherein: For each panel assembly, a region of the heat transfer fluid channel located proximate to the air flow inlet of the three-way heat exchanger is separated from the heat transfer fluid flow path by the heat transfer fluid flow guide.

11. A three-way heat exchanger operable to transfer heat between a heat transfer fluid, a liquid desiccant and air, the three-way heat exchanger comprising: a heat transfer fluid inlet manifold and a heat transfer fluid outlet manifold; as well as panel assemblies arranged with airflow gaps defined between adjacent panel assemblies to allow air to flow through the three-way heat exchanger, each panel assembly comprising: a frame defining a heat transfer fluid passage connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold for directing the flow of the heat transfer fluid through the panel assembly; two membranes positioned on the frame, each membrane defining a desiccant channel separate from the heat transfer fluid channel; and a heat transfer fluid flow guide positioned in the heat transfer fluid channel, the heat transfer fluid flow guide comprising: a sheet body; and a baffle defining a first flow path on one side of the sheet body and a second flow path on another side of the sheet body, wherein The first flow path and the second flow path are divided by the sheet body.

12. The three-way heat exchanger according to claim 11, wherein: The sheet body is shaped to allow the heat transfer fluid in the heat transfer fluid channel to flow through each flow path on each side of the sheet body.

13. The three-way heat exchanger according to claim 11, wherein: Each flow path includes a series of passages to define a serpentine path.

14. The three-way heat exchanger according to claim 11, wherein: The frame and the heat transfer fluid flow guide have complementary alignment features for orienting the heat transfer fluid flow guide in the heat transfer fluid channel.

15. The three-way heat exchanger according to claim 11, wherein: The baffle and the sheet body are integrally made of one material.

16. The three-way heat exchanger according to claim 11, wherein: Each panel assembly includes two plates, each plate being positioned between one of the membranes and the frame to separate the desiccant channel from the heat transfer fluid channel, and wherein the heat transfer fluid flow guide includes a protrusion located on the sheet body to maintain the width of the heat transfer fluid channel measured between the plates when the heat transfer fluid flows through the heat transfer fluid channel under negative pressure.

17. A heat exchanger operable to transfer heat between a heat transfer fluid and air, the heat exchanger comprising: a heat transfer fluid inlet manifold and a heat transfer fluid outlet manifold; as well as panel assemblies arranged with airflow gaps defined between adjacent panel assemblies to allow air to flow through the heat exchanger, each panel assembly comprising: a frame connected to the heat transfer fluid inlet manifold and the heat transfer fluid outlet manifold; two plates positioned on the frame, the plates and the frame defining heat transfer fluid channels for directing the heat transfer fluid through the panel assembly; and a heat transfer fluid flow guide positioned in the heat transfer fluid channel, the heat transfer fluid flow guide comprising: Sheet body; a baffle located on the sheet body, the baffle defining a flow path for the heat transfer fluid in the heat transfer fluid channel; and A protrusion is located on the sheet body to maintain a width of the heat transfer fluid channel measured between the plates when the heat transfer fluid flows through the heat transfer fluid channel under negative pressure.

18. The heat exchanger according to claim 17, wherein: The baffle, the protrusion, and the sheet body are integrally made of one material.

19. The heat exchanger according to claim 18, wherein: The one material is a polymer material.

20. The heat exchanger according to claim 17, wherein: The heat transfer fluid flow guide is capable of floating in the heat transfer fluid channel.

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