Three-way heat exchanger and heating, ventilation and air conditioning system and method of operating heat exchanger

Abstract

The invention relates to a three-way heat exchanger, a heating, ventilation and air conditioning system and a method for operating a heat exchanger. The three-way heat exchanger is operable to transfer heat between the heat transfer fluid, the liquid desiccant, and the air. A three-way heat exchanger includes an airflow inlet, an airflow outlet, and panel assemblies 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 includes: a frame defining a heat transfer fluid channel for directing a flow of a heat transfer fluid through the panel assembly; and a membrane positioned on the frame and defining a desiccant channel for the flow of liquid desiccant. The frame has a leading edge proximate the airflow inlet and a trailing edge proximate the airflow outlet. The leading edges of the frame of the panel assembly each include a leading edge aerodynamic feature.

Description

Technical Field

[0001] This field 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

[0002] Heating, ventilation, and air conditioning (HVAC) systems are known for their ability to process the heating, cooling, and moisture removal of outside air circulated through an interior space. Vapor compression cycles are 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 an evaporator coil, thereby dehumidifying the air. Since this process typically results in the dehumidified air being at an uncomfortably low temperature, the air is 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.

[0003] 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 the outside air 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 cooling and latent cooling of warm outdoor air using a heat transfer fluid and a liquid desiccant.

[0004] In the operation of a three-way heat exchanger, the liquid desiccant and the heat transfer fluid are directed through the heat exchanger, and heat is transferred between the liquid desiccant and the heat transfer fluid. An outside 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 can 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. The refrigerant subsystem engages 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 outside air.

[0005] A three-way heat exchanger may include panels that direct a heat transfer fluid and a 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 through the panels and be distributed over respective flow channels in each panel. There is a continuing need to improve the design and / or manufacturability of the panels to facilitate cost reduction and / or optimize the operation and efficiency of the heat exchanger.

[0006] 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 assist the reader in providing background information to facilitate a better understanding of the various aspects of the present disclosure. These statements are to be read from this perspective and are not to be construed as an admission of prior art. SUMMARY OF THE INVENTION

[0007] 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, and a panel assembly arranged to have an air flow gap defined between adjacent panel assemblies to permit air to flow in the air flow direction between the air flow inlet and the air flow outlet. Each panel assembly includes: a frame that defines a heat transfer fluid channel for directing a heat transfer fluid through the panel assembly; and a membrane positioned on the frame and defining a desiccant channel for the liquid desiccant to flow. Each frame has a leading edge near the air flow inlet and a trailing edge near the air flow outlet. The leading edges of the frames of the panel assembly each include leading edge aerodynamic features.

[0008] Another aspect is a heating, ventilation, and air conditioning (HVAC) system. The HVAC system includes a refrigerant subsystem and an air handling subsystem. The air handling subsystem includes a three-way heat exchanger operable to transfer heat between a heat transfer fluid, a liquid desiccant, and air, and the HVAC system is operable to circulate the heat transfer fluid between the three-way heat exchanger and the refrigerant subsystem. The three-way heat exchanger includes an air flow inlet, an air flow outlet, and a panel assembly arranged to have an air flow gap defined between adjacent panel assemblies to permit air to flow in the air flow direction between the air flow inlet and the air flow outlet. Each panel assembly includes: a frame that defines a heat transfer fluid channel for directing a heat transfer fluid through the panel assembly; and a membrane positioned on the frame and defining a desiccant channel for the liquid desiccant to flow. Each frame has a leading edge near the air flow inlet and a trailing edge near the air flow outlet. The leading edges of the frames of the panel assembly include leading edge aerodynamic features.

[0009] On the other hand, there is a method of operating a three-way heat exchanger. The method includes: guiding a heat transfer fluid through a panel assembly of the three-way heat exchanger, wherein each panel assembly includes a frame defining a heat transfer fluid passage, and the heat transfer fluid is guided through the heat transfer fluid passage; guiding a liquid desiccant through a desiccant passage of the panel assembly, the desiccant passage being defined between the frame of the panel assembly and a membrane attached to the frame; guiding air through the three-way heat exchanger in an air flow direction, wherein the air flows through an air flow gap defined between adjacent panel assemblies; and using the aerodynamic characteristics of the frame of the panel assembly to control the pressure drop of the air flowing through the air flow gap in the air flow direction.

[0010] 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 alone or in any combination. For example, each of the features discussed below with respect to any of the illustrated embodiments can be incorporated into any of the above aspects alone or in any combination. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 is a schematic flow chart of a heating, ventilation, and air conditioning (HVAC) system.

[0012] Figure 2 is included in Figure 1 is a front perspective view of a three-way heat exchanger in the HVAC system.

[0013] Figure 3 is a front perspective view of the three-way heat exchanger, wherein various components are omitted to show the internal components.

[0014] Figure 4 is a rear perspective view of the three-way heat exchanger.

[0015] Figure 5 is a rear perspective view of the three-way heat exchanger, wherein, similar to Figure 3 , various components are omitted.

[0016] Figure 6 is a front right view of the three-way heat exchanger, wherein, similar to Figure 3 and Figure 5 , various components are omitted.

[0017] Figure 7 is included in Figures 2 to 6 is a front right view of an example panel assembly in the three-way heat exchanger.

[0018] Figure 8 is Figure 7 is an exploded view of the panel assembly.

[0019] Figure 9 is a schematic cross-section of a panel assembly taken along Figure 7 section line 9-9 in

[0020] Figures 10A to 10D are, respectively Figure 8 enlarged views of sections A, B, C, and D shown in

[0021] Figure 11 is a schematic view showing a liquid desiccant and a heat transfer fluid flowing through Figures 2 to 6 a three-way heat exchanger

[0022] Figure 12 is Figure 7 an independent right front view of the frame of the panel assembly of

[0023] Figure 13 an independent front view of the frame

[0024] Figure 14 is taken along Figure 12 section 14-14 in

[0025] Figure 15 which shows the leading edge of the frame having exemplary aerodynamic features Figure 12 section line 15-15 in

[0026] Figure 16 is Figure 15 an enlarged view of the cross-section of

[0027] Figure 17 which shows exemplary aerodynamic features of the trailing edge

[0028] In the drawings, corresponding reference numerals indicate corresponding parts DETAILED DESCRIPTION

[0029] Figure 1 is a schematic view 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 stream 110 and a second inlet air stream 114, respectively, and may 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

[0030] In an example operating mode of the HVAC system 100, the conditioner subsystem 104 removes heat from the first inlet air stream 110 and directs the conditioned outlet air stream 112 to a conditioned space (not shown), such as the interior of a building structure or a vehicle. The conditioned outlet air stream 112 leaving the conditioner subsystem 104 may have a lower temperature than the first inlet air stream 110. The heat removed from the first inlet air stream 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 stream 114 and directs the heated outlet air stream 116 to the atmosphere.

[0031] 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 may include additional or other components in addition to those shown and described with reference to Figure 1 the components shown and described.

[0032] In an example operation of the refrigerant subsystem 102, the refrigerant in loop 126 is directed as low-pressure gaseous refrigerant 128 toward compressor 122. Compressor 122 compresses the gaseous refrigerant 128, which increases the temperature and pressure of the refrigerant. The pressurized hot gaseous refrigerant 130 exits compressor 122 and is directed toward condenser 120, where the high-pressure gaseous refrigerant 130 is condensed into high-pressure liquid refrigerant 132. The liquid refrigerant 132 exiting condenser 120 is directed toward expansion valve 124, which reduces the pressure of the liquid. The depressurized fluid refrigerant 134, which may be a gas or a mixture of gas and liquid after passing through expansion valve 124, is then directed toward evaporator 118. The fluid refrigerant 134 evaporates into a gas in evaporator 118 and thus exits evaporator 118 as low-pressure gaseous refrigerant 128. The gaseous refrigerant 128 is then directed back to compressor 122, where the gaseous refrigerant 128 is compressed again and the process repeats. The circulation of the refrigerant in loop 126 can be driven by compressor 122 and, more specifically, by the pressure differential that exists between the pressurized hot gaseous refrigerant 130 exiting compressor 122 and the low-pressure gaseous refrigerant 128 entering compressor 122. As Figure 1 shown, the direction of flow of the refrigerant through loop 126 can be reversed to switch the heat transfer functions of evaporator 118 and condenser 120 and enable the HVAC system 100 to operate in various operating modes.

[0033] 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 interfaces with the refrigerant subsystem 102 via evaporator 118. In particular, evaporator 118 is included in both 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 components other than those referenced Figure 1Additional components or other components other than those shown and described. For example, the conditioner subsystem 104 may include one or more pumps (not shown) for circulating the conditioner 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 conditioner 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 conditioner subsystem 104 may include additional heat transfer devices for transferring heat from the conditioner heat transfer fluid to the atmosphere or from the atmosphere to the conditioner heat transfer fluid.

[0034] In an example operation of the conditioner subsystem 104, the conditioner heat transfer fluid in loop 138 is directed towards the evaporator 118. The conditioner heat transfer fluid is cooled in the evaporator 118 as heat is transferred from the conditioner heat transfer fluid to the fluid refrigerant 134 in loop 126 to produce gaseous refrigerant 128. The cooled conditioner 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 conditioner heat transfer fluid 140, thereby heating the conditioner heat transfer fluid. The heated conditioner heat transfer fluid 142 exiting the first three-way heat exchanger 136 is directed back to the evaporator 118, and the process is repeated.

[0035] 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, ethylene glycol-based fluid, or any combination of water and ethylene glycol-based fluid) to and from the second three-way heat exchanger 144. The regenerator subsystem 106 is joined to the refrigerant subsystem 102 via the condenser 120. In particular, the condenser 120 is included in both 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 in addition to those Figure 1Additional components or other components in addition to those shown and described. For example, the regenerator subsystem 106 may include one or more pumps (not shown) for circulating 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 (such as the temperature and / or humidity of the first air inlet stream 110), the regenerator subsystem 106 may include additional heat transfer devices for transferring heat from the atmosphere into the regenerator heat transfer fluid or from the regenerator heat transfer fluid into the atmosphere.

[0036] In an example operation of the regenerator subsystem 106, the regenerator heat transfer fluid in loop 146 is directed towards the condenser 120. The regenerator heat transfer fluid is heated in the condenser as heat is transferred from the pressurized gas refrigerant 130 in loop 126 into the regenerator heat transfer fluid to produce the liquid refrigerant 132. The heated regenerator heat transfer fluid 148 leaving the condenser is directed towards 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 into the second inlet air stream 114, thereby cooling the regenerator heat transfer fluid. The heated outlet air stream 116 leaving 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 leaving the three-way heat exchanger 144 is directed back to the condenser 120, and the process is repeated.

[0037] The HVAC system 100 also includes a liquid desiccant loop 108 that operates in conjunction with subsystems 102 to 106 to facilitate conditioning of the first inlet air stream 110 through latent heat cooling and sensible heat cooling. The liquid desiccant loop 108 includes a liquid desiccant that is directed between the first three-way heat exchanger 136 and the 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.

[0038] The liquid desiccant circuit 108 may include one or more pumps (not shown) for directing 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 circuit 108 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. The liquid desiccant circuit 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.

[0039] The concentrated liquid desiccant 152 in the liquid desiccant circuit 108 is directed towards the first three-way heat exchanger 136 of the regulator 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 regulator 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 leaving the first three-way heat exchanger 136 may have lower humidity and / or lower temperature compared to the first inlet air stream 110. The liquid desiccant that has absorbed moisture from the first inlet air stream 110 leaves the first three-way heat exchanger 136 as the diluted liquid desiccant 154.

[0040] 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. Thus, the heated outlet air stream 116 leaving the second three-way heat exchanger 144 has greater humidity and higher temperature compared to the second inlet air stream 114. The liquid desiccant that has discharged moisture into the second inlet air stream 114 leaves the regenerator subsystem 106 as the concentrated liquid desiccant 152. The concentrated liquid desiccant 152 leaving the second three-way heat exchanger 144 is directed back to the first three-way heat exchanger 136, and the process is repeated.

[0041] The liquid desiccant loop 108 may also 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 reduce 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 the components shown and described.

[0042] 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 regulator subsystem 104, which transfers heat from the inlet air stream 110 to the regulator heat transfer fluid. The heat removed from the first inlet air stream 110 is then sequentially transferred among 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, and the first three-way heat exchanger 136 removes moisture from the inlet air stream 110 using the 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 then the concentrated liquid desiccant 152 is directed back to the first three-way heat exchanger 136.

[0043] The HVAC system 100 may operate in addition to the above-referencedFigure 1 Operate 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, one of the air handling subsystems 104 and 106 can be idle or omitted from the HVAC system 100 according to the operating requirements and the desired set point temperature and humidity levels in the conditioned space. For example, according to 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. according to the operating mode of the HVAC system 100.

[0044] 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 operate 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 operate in series, in parallel, or in any combination of series and parallel.

[0045] 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. 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.

[0046] 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 particular orientation.

[0047] The three-way heat exchanger 200 includes a set of panel assemblies 214 (also referred to as multi-layer panels) 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 with reference to Figures 7 to 10D Each panel assembly 214 is in the form of a plate structure having an internal heat transfer fluid passage through which a 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 passages on opposite sides of the heat transfer fluid passage. A liquid desiccant, such as the concentrated liquid desiccant 152 or the diluted liquid desiccant 154 in the liquid desiccant loop 108, flows through the liquid desiccant passages. The liquid desiccant flowing through the liquid desiccant passages is separated from the heat transfer fluid flowing through the heat transfer fluid passage of the corresponding panel assembly, and heat is exchanged between the liquid desiccant in the liquid desiccant passages and the heat transfer fluid flowing through the heat transfer fluid passage. 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.

[0048] 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.

[0049] The panel assemblies 214 are supported on the base 240 at the 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 the 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 the substantially parallel range when fluid flows through the panel assemblies 214 and / or when air flows through the air gaps 216 between adjacent panel assemblies 214. The base 240 includes a liquid desiccant reservoir (as Figure 4 and Figure 5 shown) adjacent to the air flow outlet 226 at the second longitudinal side 208 and the second vertical side 212. The liquid desiccant reservoir extends longitudinally outward beyond the panel assemblies 214, and a liquid desiccant mist eliminator may be used to collect the liquid desiccant entrained in the air flow and subsequently removed from the air flow at the air flow outlet 226. For example, the liquid desiccant mist eliminator is described in U.S. Patent Application No. 18 / 391,384 (docket number 38902-391, COP-23-073US01) entitled "LIQUID DESICCANT AIR CONDITIONER MODULES HAVING A LIQUID DESICCANT MIST TRAP" filed on December 20, 2023. The entire disclosure of this U.S. patent application is incorporated by reference.

[0050] The three-way heat exchanger 200 includes a first end plate 218 and a second end plate 220 located at the first lateral side 202 and the 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 the 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 5The end plates 218 and 220 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.

[0051] 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 Oct. 20, 2023, the entire disclosure of which is incorporated herein by reference.

[0052] 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 210 and the second vertical side 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 therebetween at the opposite vertical ends and to enclose the interior 222 of the three-way heat exchanger at the first vertical side 210 and the second vertical side 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 210 and the second vertical side 212.

[0053] The three-way heat exchanger 200 includes an air flow inlet 224 on the first longitudinal side 206 and an air flow outlet 226 on the second longitudinal side 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 filters to filter 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 an inlet air flow (e.g., Figure 1 the first inlet air flow 110 or the second inlet air flow 114 in Figure 2 to flow horizontally in the longitudinal direction (as indicated by the arrow 278 in Figure 3 through the three-way heat exchanger 200 in the air flow direction. In the illustrated example, the air flow direction 278 is in the longitudinal direction. The air flow direction 278 can additionally and / or alternatively be in the lateral direction and / or the vertical direction.Figure 5 The longitudinal side panels 228 and 230 are omitted to more clearly show the arrangement of the panel assembly 214, the air flow gap 216 defined between adjacent panel assemblies 214, and the interior 222 of the three-way heat exchanger 200.

[0054] The three-way heat exchanger 200 also 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., circulating in one of the heat transfer fluid loops 138 or 146 in Figure 1 ) enters and exits the three-way heat exchanger 200 via the heat transfer fluid inlet 232 and the heat transfer fluid outlet 234, respectively. The liquid desiccant (e.g., circulating in the liquid desiccant loop 108 in Figure 1 ) enters and exits 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 and the heat transfer fluid outlet 234, as well as 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 and the heat transfer fluid outlet 234, as well as the liquid desiccant inlet 236 and the liquid desiccant outlet 238, can each be defined by a conduit (e.g., a pipe, tube, hose, or other suitable fluid conduit) extending longitudinally through an opening in the respective end plates 218 and 220.

[0055] Referring to Figures 7 to 9 , an exemplary panel assembly 300 (also referred to as a multi-layer panel) 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 panel assembly 300 shown in Figures 7 to 9 . For ease of description, the panel assembly 214 will hereinafter be referred to 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.

[0056] 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 7A schematic cross-section of the panel assembly 300 taken along the cross-section line 9-9 therein. The spatial relationships of the components of the panel assembly 300 will be described with respect to the X, Y, and Z axes and the lateral, longitudinal, and vertical directions defined by the three-way heat exchanger 200. The panel assembly 300 will also be described in the orientation in which it is implemented and installed in the three-way heat exchanger 200. The directional terms are used only for convenience in describing the components of the panel assembly 300. The examples shown and described are not limited to any particular orientation.

[0057] 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 on the Z axis, a first lateral face 305 and a second lateral face 307 on the X axis, and a first longitudinal end 308 and a second longitudinal end 310 on the Y axis. The frame 302 includes opposite first header segments 312 and second header segments 314 located at the first vertical end 304 and the second vertical end 306, respectively. The frame 302 also includes an intermediate segment 316 located between the opposite header segments 312 and 314. The header segments 312 and 314 define liquid desiccant header regions 320 and 322, respectively. The intermediate segment 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 (not labeled) (or "frame bars") of the frame 302 that extend between the heat transfer fluid region 324 and one of the liquid desiccant header regions 320 and 322. The intermediate segment 316 defines a leading edge 388 and a trailing edge 390 of the frame 302. The leading edge 388 extends between the header segments 312 and 314 near the first longitudinal end 308, and the trailing edge 390 extends between the header segments 312 and 314 near the second longitudinal end 310. The leading edge 388 and / or the trailing edge 390 may include aerodynamic features 392 (e.g., see Figure 12 ) that facilitate controlling the pressure drop of the air flowing through the air flow gap 216 and / or reducing the resistance of the air flowing through the air flow gap 216, which will be described in more detail below.

[0058] Each manifold section 312, 314 of the frame 302 includes complementary airflow limiter members (not labeled) that cooperate or engage with the airflow limiter members of the adjacent panel assemblies 300 when the heat exchanger 200 is assembled to form an airflow limiter in the airflow gap 216 between adjacent panel assemblies at opposite vertical ends. The airflow limiter is described in U.S. Patent Application No. 18 / 390,948, filed Dec. 20, 2023, entitled “LIQUID DESICCANT AIR CONDITIONER MODULES HAVING INTERLOCKING PANELS FOR CONTROLLING AIRFLOW” (Docket No. 38902-390, COP-24-001US01), the entire disclosure of which is incorporated by reference.

[0059] The panel assemblies 300 also include 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 sheets of material, such as 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 Jun. 1, 2021, U.S. Patent No. 10,921,001, issued Feb. 16, 2021, and U.S. Patent Application No. 18 / 390,475, filed Dec. 20, 2023, entitled “SYSTEMS AND METHODS FOR ASSEMBLING LIQUID DESICCANT AIR CONDITIONER PANELS USING FLEXIBLE ALIGNMENT FEATURES” (Docket No. 38902-387, COP-23-074US01), the entire disclosures of which are incorporated by reference.

[0060] 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 frame 302 can be made of a thermoplastic or polymer, for example, using an injection molding process. The plates 326, 328 can be made of a thermoplastic or polymer, for example, using a thermoforming process and / or by die cutting. 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.

[0061] The sheets or 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 exemplary 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 the exemplary 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.

[0062] A mesh or perforation (not shown) can be provided in the heat transfer fluid passage 330 to maintain the width of the heat transfer fluid passage under negative pressure. The mesh or perforation can also promote a more constant flow rate of the heat transfer fluid through the passage 330. The mesh or perforation can also help improve the flow distribution of the heat transfer fluid between the panel assemblies 300 in the three-way heat exchanger 200. The mesh or perforation can also provide turbulence of the heat transfer fluid to increase heat transfer with the liquid desiccant flowing on the outer surfaces of the sheets or plates 326 and 328. A variety of materials can be used for the mesh or perforation. For example, the mesh or perforation can comprise the same polymeric material as the plates (e.g., polyolefin, ABS, or combinations thereof). Alternatively, flow guides (not shown) can be provided in the heat transfer fluid passage 330. Exemplary flow guides are described in U.S. Patent Application No. 18 / 585,344, filed Feb. 23, 2024, entitled "THREE-WAY HEAT EXCHANGE MODULE WITH CONTROLLED FLUID FLOW" (Docket No. 38902-413; COP-23-049US01), the entire disclosure of which is incorporated herein by reference.

[0063] Referring again to Figures 7 to 9 , the panel assembly 300 also 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 can be included in the panel assembly 300. The membranes 332 and 334 cover the outer surfaces of the sheets or plates 326 and 328. As Figure 9As shown, liquid desiccant channels 336 and 338 are defined between membrane 332 and plate 326 and between membrane 334 and plate 328, respectively. Membranes 332 and 334 also encapsulate and seal liquid desiccant header regions 320 and 322. Each of liquid desiccant channels 336 and 338 fluidly connects liquid desiccant header regions 320 and 322. As described below, in an exemplary operation of the three-way heat exchanger 200, liquid desiccant flows through one of liquid desiccant header regions 320 or 322, enters liquid desiccant channels 336 and 338, above the outer surfaces of plates 326 and 328 and behind membranes 332 and 334, and ultimately enters the other of liquid desiccant header regions 320 or 322. Plates 326 and 328 limit contact between the liquid desiccant flowing in liquid desiccant channels 336 and 338 and the heat transfer fluid flowing through heat transfer fluid channels 330 and enable heat transfer therebetween. In examples where only one of membranes 332 or 334 is included in the panel assembly 300, only one liquid desiccant channel 336 or 338 may be defined between membrane 332 or 334 and plate 326 or 328. In these examples, plates 326 or 328 on lateral faces 305 or 307 opposite liquid desiccant channels 336 or 338 may encapsulate and seal liquid desiccant header regions 320 and 322 and limit the flow of liquid desiccant opposite liquid desiccant channels 336 or 338.

[0064] Membranes 332 and 334 are attached to one of the lateral faces 305 and 307 of the frame 302, respectively, 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 sheets or plates 326 and 328, which can help maintain the widths of the liquid desiccant channels 336 and 338 and / or limit the tendency of membranes 332 and 334 to bulge outward as liquid desiccant flows through the liquid desiccant channels 336 and 338. Membranes 332 and 334 can be attached to the lateral faces 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 attached directly to the plates 326 and 328 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 the 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 the plates 326 and 328 can include raised patterns or dot features (not shown) to which the 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 the membranes 332 and 334 to the dot features or raised patterns can provide the additional advantage of promoting the uniform distribution of liquid desiccant across the liquid desiccant channels 336 and 338 in the longitudinal direction and reducing the stresses that can cause the plates 326 and 328 to warp. 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 during exemplary operation of the three-way heat exchanger 200. Additional details regarding example systems and methods for attaching the membranes 332 and 334 to the frame 30 and the respective sheets or plates 326 and 328 are described, for example, in U.S. Patent No. 11,022,330, issued June 1, 2021, U.S. Patent No. 10,921,001, issued February 16, 2021, and U.S. Patent Application No. 18 / 390,475, filed December 20, 2023, entitled "SYSTEMS AND METHODS FOR ASSEMBLING LIQUID DESICCANT AIR CONDITIONER PANELS USING FLEXIBLE ALIGNMENT FEATURES" (Docket No. 38902-387, COP-23-074US01), the entire disclosures of which are incorporated by reference herein.

[0065] 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, 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 membranes 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 past the membranes 332 and 334 or desorb water into the air flowing past the membranes 332 and 334.

[0066] 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, respectively, are located on opposite longitudinal and vertical ends of the panel assembly 300.

[0067] As represented by Figure 7 and Figure 9 the flow lines 344 in, in an exemplary 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. The liquid desiccant may have an alternative flow direction. The flow direction of the liquid desiccant in the channels 336, 338 may vary depending on, for example, the orientation of the panel assembly 300 in the heat exchanger 200, the positions of the liquid desiccant inlet port 340 and the liquid desiccant outlet port 342, and / or which liquid desiccant manifold region 320, 322 the liquid desiccant is supplied to and from which manifold region the liquid desiccant exits.

[0068] The frame 302 also defines a heat transfer fluid inlet port 346 for supplying heat transfer fluid into the heat transfer fluid channel 330 and a heat transfer fluid outlet port 348 for receiving heat transfer fluid from the heat transfer fluid channel 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 manifold section 314 and the intermediate section 316. The third corner flange 368 is positioned adjacent to the heat transfer fluid channel 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 manifold section 312 and the intermediate section 316. The fourth corner flange 370 is positioned adjacent to the heat transfer fluid channel 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, respectively, are located on opposite longitudinal 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, respectively, are both 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, respectively, are both positioned near the second vertical end 306 on opposite longitudinal ends of the panel assembly.

[0069] As represented byFigure 7 and Figure 9 As represented by flow line 350 in Figure 9 , in an exemplary operation of the three-way heat exchanger 200, the heat transfer fluid is supplied via the heat transfer fluid inlet port 346 into the heat transfer fluid passage 330 of the panel assembly 300, flows therethrough, 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. The heat transfer fluid may have an alternative flow direction. The flow direction of the heat transfer fluid in the passage 330 may 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 port 346, 348 the heat transfer fluid enters the passage 330 through and which port it exits the passage 330 through.

[0070] Figures 10A to 10D are respectively Figure 8 enlarged views of portions A, B, C, and D of the illustrated frame 302, and more particularly depict the corner flanges 364 to 370. In particular, Figures 10A to 10D shown are the microchannels or orifices that provide fluid connection between the ports 340, 342, 346, and 348 defined in the panel assembly 300 and the respective fluid regions. As Figure 10A and Figure 10B shown in Figure 10A and Figure 10B , the heat transfer fluid inlet port 346 is connected to the heat transfer fluid region 324 through an orifice 352 ( Figure 10B ), and the heat transfer fluid outlet port 348 is connected to the heat transfer fluid region 324 through an orifice 354 ( Figure 10A ). The heat transfer fluid region 324 defines the heat transfer fluid passage 330 when sealed to the opposite lateral faces 305 and 307 of the frame 302 by plates 326 and 328. As indicated by the flow line 350 in Figure 10A and Figure 10B , the heat transfer fluid enters the heat transfer fluid passage 330 from the inlet port 346 via the orifice 352 and exits the passage 330 via the orifice 354 into the outlet port 348.

[0071] As Figure 10C and Figure 10D shown in Figure 10C and Figure 10D , the liquid desiccant inlet port 340 is connected to the first liquid desiccant header region 320 through an orifice 356 ( Figure 10C ) and the liquid desiccant outlet port 342 is connected to the second liquid desiccant header region 322 through an orifice 358 ( Figure 10D ). As indicated by Figure 10C and Figure 10DAs indicated by the flow line 344 therein, the liquid desiccant enters the first liquid desiccant manifold region 320 from the inlet port 340 via the orifice 356, flows into and through the liquid desiccant channels 336 and 338( Figure 9 ), enters the second liquid desiccant manifold region 322, and leaves the manifold region 322 via the orifice 358 and enters the outlet port 342. In the Figures 10A to 10D illustrated example, each of the orifices 352 to 358 includes two orifices. Any suitable number of orifices may be used for the orifices 352 to 358. In some examples, for some of the orifices 352 to 358, a greater number of orifices may be used than for other orifices 352 to 358. The number, size, and / or shape of the orifices 352 to 358 may be the same or different. The number, size, and shape of the orifices used for each of the orifices 352 to 358 may also vary between the panel assemblies 300.

[0072] Figures 10A to 10D Also shown are exemplary features of the panel assembly 300 that may facilitate connecting adjacent panel assemblies 300 when installed in the three-way 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 may be connected. As shown, each of the corner flanges 364 to 370 includes one or more snap fittings 372. The snap fittings 372 extend laterally from the first lateral face 305 of the frame 302, and the corresponding holes 374( Figure 6 shown therein) 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.

[0073] Each of the corner flanges 364-370 also includes one or more alignment holes 376 extending therethrough in a lateral direction. In the illustrated embodiment, each of the corner flanges 364-370 includes two alignment holes 376, labeled as a first alignment hole 376a and a second alignment hole 376b in Figures 10A to 10D . The first alignment hole 376a of each of the corner flanges 364-370 is longitudinally inward of the second alignment hole 376b and adjacent to the respective corner of the heat transfer fluid region 324. In other examples, more or fewer alignment holes 376 may be included at the corner flanges 364-370. The corner flanges 364-370 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 364-370 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 openings 258 of the first end plate 218 and one of the alignment openings 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 openings 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 not through the end plates 218 and 220.

[0074] 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 within the corner flange. The flange collar 378 extends in a lateral direction from a first lateral face 305 of the frame 302. Each corner flange 364 to 370 also includes a corresponding grooved 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 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 panel assembly 300 in the panel assemblies 300 is received by one of the grooved nozzles 380 of the corresponding corner flanges 364 to 370 of the frame 302 of a 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 grooved nozzle 380 and insertion of the flange collar 378 into the grooved nozzle 380. The guide teeth 382 may include guiding features (e.g., chamfers) for more easily inserting the teeth and the flange collar 378 into the corresponding grooved nozzle 380. An elastomeric seal (not shown), such as an O-ring, may be seated within each of the grooved nozzles 380 and forms a fluid-tight seal at the adjacent fluid ports 340, 342, 346, 348 between the adjacent panel assemblies 300 when the flange collar 378 is inserted into the grooved nozzle 380.

[0075] Also refer to Figure 3 and Figure 5 and shows a left view of a three-way heat exchanger 200 similar to Figure 3 and Figure 5 with various components omitted Figure 6 , the panel assemblies 300 are arranged in sequence or in series in the lateral direction as described above. In Figure 3 , Figure 5 and Figure 6For ease of illustration, the plates 326 and 328 and the 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 near the longitudinal ends 308 and 310 and corresponding holes 374 (as Figure 6 and Figure 7 shown). The snap fittings 372 and the corresponding holes 374 located on the intermediate section 316 of the frame 302 may facilitate connecting 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.

[0076] The width of each air flow gap 216 may be, for example, between about 1 millimeter (mm) and about 20 mm, such as between about 1 mm and about 10 mm, between about 10 mm and about 20 mm, between about 5 mm and about 15 mm, between about 1 mm and about 5 mm, between about 5 mm and about 10 mm, between about 10 mm and about 15 mm, or between about 15 mm and about 20 mm. When air flows through the air flow gap 216, the width of the air flow gap 216 may be maintained by the spacers 386.

[0077] The panel assembly 300 is disposed within the three-way 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 portion 202 and the second lateral side portion 204 of the three-way heat exchanger 200. The first longitudinal end 308 and the second longitudinal end 310 are respectively located at the first longitudinal side portion 206 and the second longitudinal side portion 208 of the three-way heat exchanger 200, and the first vertical end 304 and the second vertical end 306 are respectively located at the first vertical side portion 210 and the second vertical side portion 212 of the three-way heat exchanger 200. The leading edge of the frame 302 positioned near the first longitudinal end 308 is near the air inlet 224. The trailing edge of the frame 302 near the second longitudinal end 310 is near the air outlet 226.

[0078] 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 the lateral direction, through which the heat transfer fluid and the liquid desiccant flow into and out of the panel assembly 300 between the first lateral side portion 202 and the second lateral side portion 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 portion 202 and the second lateral side portion 204 near the first vertical side portion 210 and the second longitudinal side portion 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 portion 202 and the second lateral side portion 204 near the second vertical side portion 212 and the first longitudinal side portion 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 portion 202 and the second lateral side portion 204 near the second vertical side portion 212 and the second longitudinal side portion 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 portion 202 and the second lateral side portion 204 near the first vertical side portion 210 and the first longitudinal side portion 206 of the three-way heat exchanger 200.

[0079] 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, in each of the corner flanges 364 to 370, the snap fittings 372, the corresponding holes 374, and the alignment holes 376 together surround the fluid ports 340, 342, 346, 348 defined in the corner flanges, which may help create and maintain a fluid-tight seal between the adjacent ports 340, 342, 346, 348 that define the manifolds 242 to 248.

[0080] As Figure 3 and Figure 5 shown, conduits 250, 252, 254, and 256 are used to fluidly connect the heat transfer fluid inlet 232 and outlet 234, and the liquid desiccant inlet 236 and outlet 238 to the respective 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. The conduits 250 to 256 may 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 the conduits 250 to 256 may be attached to the respective manifolds 242 to 248 by coupling the end of the conduit to the end panel assembly 300 (i.e., the panel assembly 300 adjacent to the lateral sides 202 or 204) at an appropriate one of the ports 340, 342, 346, and 348. The conduits 250 to 256 may 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.

[0081] The conduits 250 and 256 extend between the end plate 218 and the end panel assembly 300 at the first lateral side 202. The conduits 252 and 254 extend between the end plate 220 and the end panel assembly 300 at the second lateral side 204. The conduits 250 and 256 may extend through the end plate 218 to respectively define an inlet 236 or an outlet 234, may be coupled to the corresponding inlet 236 or outlet 234 defined by the end plate 218, or may be integrally formed with the end plate 218 and the corresponding inlet 236 or outlet 234 defined by the end plate 218. The conduits 252 and 254 may extend through the end plate 220 to respectively define an outlet 238 or an inlet 232, may be coupled to the corresponding outlet 238 or inlet 232 defined by the end plate 220, or may be integrally formed with the end plate 220 and the corresponding outlet 238 or inlet 232 defined by the end plate 220.

[0082] Each of the manifolds 242 to 248 may be closed at the 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 corresponding lateral sides 202 or 204 by the end plate 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 the end 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 the end 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 above 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 above 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.

[0083] Now refer to Figure 11 , and 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 Figure 11 schematic view, for ease of illustration and description, the panel assembly 300 is depicted with exaggerated and / or simplified features.

[0084] In an exemplary operation of the heat exchanger 200, an inlet air stream (e.g., Figure 1 the first inlet air stream 110 or the second inlet air stream 114 shown in Figure 1 ) enters via the air flow inlet 224 and flows in the air flow direction 278 through the air gap 216 defined between adjacent panel assemblies 300. The air flowing through the air gap 216 is directed through the liquid desiccant indicated by the flow line 344 and the heat transfer fluid indicated by the flow line 350 in each panel assembly of the panel assembly 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

[0085] 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 the regenerator heat transfer fluid from the Figures 3 to 5 regenerator subsystem 106 shown in Figure 7 and Figure 8 and the heat exchanger 200 is used to heat moisture and discharge the moisture into the air flowing through the air gap 216. Figure 7 and Figure 8 The liquid desiccant 344 flows from the first side lateral portion 202 into the liquid desiccant inlet manifold 242 via the liquid desiccant inlet 236 and the conduit 250 (as shown in ) enters the liquid desiccant manifold region 322. As 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 exits each panel assembly 300 via the orifice 358 from the respective liquid desiccant manifold region 322 and flows toward the second lateral side 204 through the liquid desiccant outlet manifold 244. The liquid desiccant 344 exits the heat exchanger 200 via the conduit 252 and the liquid desiccant outlet 238 ( Figure 5 as shown in ).

[0086] 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 the conduit 254 ( Figure 4 and Figure 5 as shown in ). The heat transfer fluid 350 enters each panel assembly 300 via the orifice 352 from the heat transfer fluid inlet manifold 246. 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 in ).

[0087] 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 in the panel assembly 300. In these examples, the directions in which the liquid desiccant 344 flows 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 in which the heat transfer fluid 350 flows 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.

[0088] An inlet air stream entering via the air flow inlet 224 flows over the leading edge 388 of the panel assembly 300, is distributed into the air flow gap 216, exchanges heat and moisture in the air flow gap 216, then flows over the trailing edge 390 of the panel assembly and exits via the air flow outlet 226. The leading edge and / or trailing edge of the frame 302 may tend to create drag on the inlet air stream flowing through the air flow gap 216. This may have a negative impact on the performance and / or efficiency of the heat exchanger 200. For example, increased drag on the inlet air stream flowing through the air flow gap 216 can create a relatively high pressure drop in the air flow direction 278 ( Figure 2 ), which may increase energy consumption (e.g., by increasing the fan power required to direct the inlet air stream through the heat exchanger 200). Additionally and / or alternatively, increased drag on the inlet air stream may reduce the amount of heat and / or moisture that can be transferred between the inlet air stream and the heat transfer fluid and liquid desiccant flowing through the panel assembly 300, thereby reducing the efficiency of the heat exchanger 200. The negative impact of air drag on the efficient and effective operation of the heat exchanger 200 may be exacerbated under certain operating conditions of the heat exchanger 200 (e.g., a relatively high velocity air stream) and / or size configurations (e.g., an air flow gap 216 having a width between 1 mm and about 20 mm).

[0089] Referring to Figure 12 , Figure 12 is a separate right side elevation view of the frame 302, with the leading edge 388 having an aerodynamic feature 392 that facilitates controlling the pressure drop and / or drag of the inlet air stream flowing through the air flow gap 216. The aerodynamic feature 392 may be an aerodynamic profile 394 of the leading edge 388 ( Figure 14)。The aerodynamic profile 394 of the leading edge 388 can have any suitable shape. For example, the aerodynamic profile 394 can be arcuate or any other suitable shape such that the aerodynamic feature 392 can function as described. Example arcuate shapes for the aerodynamic profile 394 include bullet shapes, nose cone shapes (e.g., conical shapes, bi-conical shapes, elliptical shapes, frustoconical shapes, blunt shapes), parabolic shapes, spherical shapes (e.g., spheres or spheres with fairings), lens shapes, etc. The aerodynamic feature 392 and the frame 302 can be integrally formed from a single material, such as a polymeric material or a thermoplastic material (e.g., polyolefins, such as polypropylene and / or polyethylene). For example, the aerodynamic feature 392 and the frame 302 can be integrally formed from a thermoplastic material or a polymeric material using injection molding. Integrally manufacturing the aerodynamic feature 392 and the frame 302 from a single material can provide the additional advantage of material and cost savings during the manufacture of the frame 302. Alternatively, the aerodynamic feature 392 can be a separate piece (e.g., a blade or an airfoil) attached to the leading edge 388 of the frame 302. In these examples, the aerodynamic feature 392 can be attached to the trailing edge 388 by welding, adhesive bonding, thermal bonding, or another suitable technique for joining materials together.

[0090] Figure 14 is a cross-section taken along Figure 12 14-14 in FIG. which shows an example aerodynamic profile 394 of the leading edge 388 having an arcuate (e.g., bullet-shaped) shape. The aerodynamic profile 394 causes the width (or thickness) of the leading edge 388 measured between the lateral faces 305, 307 of the frame 302 to taper from a main thickness T1 at the middle section 316 to a minimum thickness T2 at the outermost portion of the leading edge 388 over a length L1. The dimensions T1, T2, and L1 can vary depending on the dimensions of the frame 302, which can depend on the operating requirements of the heat exchanger 200. In some examples, the main thickness T1 of the middle section 316 is between about 2 mm and about 4 mm, such as between about 2.5 mm and about 3 mm, and the minimum thickness T2 of the leading edge 388 is between about 0.5 mm and about 2 mm, such as between about 0.7 mm and about 1 mm. The length L1 of the leading edge 388 between the thickness T1 and the thickness T2 can be between about 4 mm and about 6 mm, such as between about 5 mm and about 5.5 mm. The arcuate aerodynamic profile 394 can have a radius R1 between about 10 mm and about 20 mm, such as between about 15 mm and about 17 mm. In an example where the aerodynamic profile 394 is a frustoconical shape (e.g., a frustoconical shape), the aerodynamic profile 394 can be straight within the range between the thickness T1 and the thickness T2, and its angle is between about 5° and about 15°, such as between about 8° and about 10°. AsFigure 14 As shown, when the leading edge 388 extends from the minimum thickness T2 to the main thickness T1 on the two lateral faces 305, 307 of the frame 302, the aerodynamic profile 394 is symmetric in shape. The symmetric shape of the aerodynamic profile 394 facilitates providing an aerodynamic function for the inlet air flow in the air flow gap 216 allocated to both the lateral faces 305 and 307 of the adjacent frame 302.

[0091] Referring to Figure 13 , Figure 13 is an independent front view of the frame 302, and the main width or main thickness T1 ( Figure 14 ) of the middle section is reduced relative to the width or thickness of the header sections 312, 314 of the frame 302. The reduced width of the middle section 316 enables the adjacent panel assemblies 300 to be laterally spaced apart on their adjacent middle sections 316 to define the air flow gap 216. The relatively large thickness of the frame 302 at the header sections 312, 314 enables the adjacent panel assemblies 300 to be connected at their adjacent header sections 312, 314 (e.g., via the corner flanges 364 to 370 as described above, for example, referring to Figures 10A to 10D ). The thickness of the frame 302 at the header sections 312, 314 can be, for example, between about 4 mm and about 8 mm, such as between about 5 mm and about 7 mm, or between about 6 mm and about 6.5 mm.

[0092] The thickness difference between the middle section 316 and the header sections 312, 314 of the frame 302 can depend on the desired width of the air flow gap 216 between the adjacent panel assemblies 300. The width of the air flow gap 216 can vary according to the operating requirements of the heat exchanger 200. The relatively small width of the air flow gap 216 can increase the surface contact area between the inlet air flow and the membranes 332 and 334, which can improve the efficiency of the heat exchanger 200. Additionally and / or alternatively, the smaller width of the air flow gap 216 can reduce the footprint of the heat exchanger 200, which can facilitate improving the ease of manufacture, assembly, and / or installation of the heat exchanger. In some examples, the width of each air flow gap 216 can be, for example, between about 1 mm and about 20 mm, such as between about 1 mm and about 10 mm, between about 10 mm and about 20 mm, between about 5 mm and about 15 mm, between about 1 mm and about 5 mm, between about 5 mm and about 10 mm, between about 10 mm and about 15 mm, or between about 15 mm and about 20 mm. As described above, reducing the width of the air flow gap 216 to this range may require controlling the pressure drop and / or resistance of the inlet air flow. This control can be facilitated by the aerodynamic features 392 of the leading edge 388 of the panel assembly (and / or the aerodynamic features 396 of the trailing edge 390 described below).

[0093] The relatively small thickness of the intermediate section 316 of the panel assembly 300 may cause the panel assembly to tend to deform (e.g., warp) under the influence of the inlet air flow. In an example operation of the heat exchanger 200, the air flow gap 216 can be maintained by supports or spacers 386 that laterally extend between the intermediate sections 316 of adjacent panel assemblies 300. In the illustrated example, the spacers 386 are positioned adjacent to both longitudinal ends 308, 310 of the frame 302 in a vertical arrangement. The spacer 386 near the first longitudinal end 308 is located between the heat transfer fluid region 324 and the leading edge 388 of the frame 302. The spacer 386 near the second longitudinal end 310 is located between the heat transfer fluid region 324 and the trailing edge 390 of the frame 302. In the illustrated example, the spacer 386 laterally extends from the first lateral face 305 of the frame 302. In other examples, the spacer 386 can additionally and / or alternatively laterally extend from the second lateral face 307 of the frame 302. A mating member 387 corresponding to the spacer 386 (shown in Figure 13 ) can be located on the opposite lateral face (in this example, the lateral face 307). The mating member 387 can receive the spacer 386 of the adjacent frame 302 and enable the spacer 386 to function as described. The spacer 386 can be the snap-fit fitting 372 described above, and the mating member 387 can be the corresponding hole 374.

[0094] Figure 15 is a cross-section taken along line 15-15 in Figure 12 and depicts the trailing edge 390 of an example frame 302. In this example, the trailing edge 390 does not include aerodynamic features and is rectangular in shape. In other examples, such as in the example shown in Figure 16 , the trailing edge 390 can include aerodynamic features 396. In addition to or as an alternative to the aerodynamic features 392 of the leading edge 388, the aerodynamic features 396 of the trailing edge 390 can facilitate controlling the pressure drop and / or resistance of the inlet air flow passing through the air flow gap 216. In Figure 16In the example of, the aerodynamic feature 396 of the trailing edge 390 is an aerodynamic profile 398 that is arcuate in shape and symmetric with the aerodynamic profile 394 of the leading edge 388. In particular, the aerodynamic profile 398 causes the width (or thickness) of the trailing edge 390 measured between the lateral faces 305, 307 of the frame 302 to taper from the main thickness T1 of the middle section 316 to a minimum thickness T3 at the outermost portion of the trailing edge 390 over a length L2, and the dimensions T3, L2, and radius R2 of the trailing edge aerodynamic profile 398 are symmetric with the dimensions T2, L1, and R1 of the leading edge aerodynamic profile 394, respectively. The trailing edge aerodynamic profile 398 can have any suitable shape, including those described above for the leading edge aerodynamic profile 394. The leading edge aerodynamic profile 394 can be symmetric or asymmetric with the trailing edge aerodynamic profile 398. The trailing edge aerodynamic feature 396 and the frame 302 can be integrally formed from a single material, such as a polymeric material or a thermoplastic material (e.g., polyolefins such as polypropylene and / or polyethylene). For example, the trailing edge aerodynamic feature 396 and the frame 302 can be integrally formed from a thermoplastic material or a polymeric material using injection molding. Alternatively, the aerodynamic feature 396 can be a separate piece (e.g., a vane or an airfoil) attached to the trailing edge 390 of the frame 302. As described above for the leading edge aerodynamic feature 392, the trailing edge aerodynamic feature 396 can be attached to the trailing edge 390 by welding, adhesive bonding, thermal bonding, or another suitable technique for joining materials together.

[0095] Figure 17An example method 400 of operating a three-way heat exchanger, e.g., three-way heat exchanger 200, is provided. Method 400 includes directing 402 a heat transfer fluid through a panel assembly 300 of the three-way heat exchanger 200. Each panel assembly includes a frame 302 that defines a heat transfer fluid passage 330 through which the heat transfer fluid is directed. Method 400 also includes directing 404 a liquid desiccant through desiccant passages 336, 338 of the panel assembly 300. The desiccant passages 336, 338 are defined between the frame 302 of the panel assembly 300 and membranes 332, 334, each of which is attached to one of the frames 302 in the frame. Method 400 also includes directing 406 an inlet air stream through the three-way heat exchanger 200 along an air flow direction 278. The inlet air stream flows through an air flow gap 216 defined between adjacent panel assemblies 300. Method 400 also includes controlling 408 a pressure drop of the inlet air stream flowing through the air flow gap 216 along the air flow direction 278 using aerodynamic features 392 and / or 396 of the frame 302 of the panel assembly 300. The aerodynamic features 392 and / or 396 can also facilitate controlling the resistance on the air stream as the air stream flows through the air flow gap 216. The inlet air stream can flow through the air flow gap 216 at a speed between about 100 feet per minute (FPM) and about 350 FPM, such as between about 200 FPM and about 300 FPM. The air flow gaps 216 can each have a width, for example, between about 1 mm and about 20 mm, such as between about 1 mm and about 10 mm, between about 10 mm and about 20 mm, between about 5 mm and about 15 mm, between about 1 mm and about 5 mm, between about 5 mm and about 10 mm, between about 10 mm and about 15 mm, or between about 15 mm and about 20 mm. The width of the air flow gaps 216 can be maintained under the influence of the inlet air stream using spacers 386 positioned between adjacent frames 300.

[0096] The example systems and methods described include a three-way heat exchanger operable to remove heat and moisture from an air stream and / or discharge heat and moisture into an air stream. The three-way heat exchanger can include a panel assembly through which a heat transfer fluid and a liquid desiccant are directed, and an air flow gap defined between adjacent panel assemblies for directing air therethrough. Example panel assemblies of the three-way heat exchanger include a frame, two sheets attached to the frame to define a heat transfer fluid passage, and membranes attached to each sheet to define a desiccant passage. The frame can include aerodynamic features (e.g., an aerodynamic profile or airfoil) at a leading edge and / or a trailing edge, the aerodynamic features operable to control the pressure drop and / or resistance of air flowing through the air flow gap. Controlling the pressure drop and resistance of air flowing through the heat exchanger can facilitate operating the three-way heat exchanger under desired operating conditions, such as at a desired air velocity and / or a desired air flow gap width, which can increase the surface contact area between the air and the panel assembly, reduce the total footprint of the heat exchanger, and otherwise improve the efficiency of the heat exchanger and / or improve the ease of manufacture, assembly, and / or installation of the heat exchanger.

[0097] Embodiments of HVAC systems and methods of operating the systems have been described in detail above. The systems and methods are not limited to the specific embodiments described herein, but rather, components of the systems and methods can be used independently and separately from other components described herein. For example, the systems and methods described herein can be used in systems other than HVAC systems.

[0098] When introducing elements of the present disclosure or embodiments thereof, the articles “a,” “an,” “the,” and “said” are intended to mean that there is one or more of the elements. The terms “comprising,” “including,” “having,” and “containing” are intended to be inclusive and mean that additional elements may be present in addition to the recited elements. The use of terms indicating a particular orientation (e.g., “top,” “bottom,” “side,” “vertical,” “lateral,” “longitudinal,” etc.) is for ease of description and does not require any particular orientation of the items described.

[0099] The terms “about,” “substantially,” “essentially,” and “approximately” and their equivalents, when used in connection with a range of dimensions, concentrations, temperatures, or other physical or chemical properties or characteristics, mean to encompass variations that may exist in the upper and / or lower limits of the range of the property or characteristic, including, for example, variations caused by rounding, measurement methods, or other statistical variations.

[0100] Since various changes can 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; as well as The panel assemblies are arranged to have 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 channel for directing the flow of the heat transfer fluid through the panel assembly, wherein the frame has a leading edge proximate the airflow inlet and a trailing edge proximate the airflow outlet; and a membrane positioned on the frame and defining a desiccant channel for flow of the liquid desiccant; Wherein the leading edges of the frames of the panel assemblies each include a leading edge aerodynamic feature.

2. The three-way heat exchanger according to claim 1, wherein: For each panel assembly, the leading edge aerodynamic characteristic is an aerodynamic profile of the leading edge.

3. The three-way heat exchanger according to claim 2, wherein: For each panel assembly, the aerodynamic profile is the arcuate shape of the leading edge.

4. The three-way heat exchanger according to claim 1, wherein: For each panel assembly, the leading edge aerodynamic feature and the frame are integrally formed from one material.

5. The three-way heat exchanger according to claim 4, wherein: For each panel assembly, the leading edge aerodynamic features and the frame are integrally formed from an injection molded polymer material.

6. The three-way heat exchanger according to claim 1, wherein: The trailing edge of the frame of the panel assembly includes a trailing edge aerodynamic feature.

7. The three-way heat exchanger according to claim 6, wherein: For each panel assembly, the leading edge aerodynamic feature and the trailing edge aerodynamic feature are symmetrical in shape.

8. The three-way heat exchanger according to claim 1, wherein: For each panel assembly, the frame has a middle section and two header sections at opposite ends of the middle section, wherein the middle section defines the leading edge and the trailing edge each extending between the header sections.

9. The three-way heat exchanger according to claim 8, wherein: For each pair of adjacent panel assemblies, adjacent said header sections are connected, and said air flow gap is defined between adjacent said intermediate sections.

10. The three-way heat exchanger according to claim 8, wherein: For each pair of adjacent panel assemblies, a spacer is positioned between adjacent intermediate sections, wherein the spacer is located between the heat transfer fluid channel and each of the leading edge and the trailing edge of an adjacent frame.

11. The three-way heat exchanger according to claim 1, wherein: The three-pass heat exchanger is operable at air velocities between 100 feet per minute and 350 feet per minute, and the leading edge aerodynamic features operate to control a pressure drop of air in the direction of airflow.

12. The three-way heat exchanger according to claim 1, wherein: The airflow gap has a width between 1 millimeter and 20 millimeters measured between adjacent the panel assemblies, and the leading edge aerodynamic features operate to control a pressure drop of air in the airflow direction.

13. A heating, ventilation and air conditioning system comprising: Refrigerant subsystem; as well as an air handling subsystem, the air handling subsystem comprising a three-way heat exchanger operable to transfer heat between a heat transfer fluid, a liquid desiccant and air, the heating, ventilation and air conditioning system operable to circulate the heat transfer fluid between the three-way heat exchanger and the refrigerant subsystem, wherein the three-way heat exchanger comprises: an airflow inlet and an airflow outlet; and The panel assemblies are arranged to have 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 channel for directing the flow of the heat transfer fluid through the panel assembly, wherein the frame has a leading edge proximate the airflow inlet and a trailing edge proximate the airflow outlet; and a membrane positioned on the frame and defining a desiccant channel for flow of the liquid desiccant; Wherein the leading edges of the frames of the panel assemblies each include a leading edge aerodynamic feature.

14. The heating, ventilation and air conditioning system of claim 13, wherein: For each panel assembly of the three-way heat exchanger, the leading edge aerodynamic feature is an aerodynamic profile of the leading edge.

15. The heating, ventilation and air conditioning system of claim 13, wherein: For each panel assembly of the three-way heat exchanger, the leading edge aerodynamic features and the frame are integrally formed from one material.

16. The HVAC system of claim 13, wherein: For each panel assembly of the three-way heat exchanger, the trailing edge of the frame includes a trailing edge aerodynamic feature.

17. The heating, ventilation and air conditioning system of claim 13, wherein: For each panel assembly of the three-way heat exchanger, the frame has a middle section and two header sections at opposite ends of the middle section, wherein the middle section defines the leading edge and the trailing edge each extending between the header sections.

18. A method of operating a heat exchanger, the method comprising: directing a heat transfer fluid through a panel assembly of a three-way heat exchanger, wherein each panel assembly includes a frame defining a heat transfer fluid passage through which the heat transfer fluid is directed; directing a liquid desiccant through a desiccant passage of the panel assembly, the desiccant passage being defined between the frame of the panel assembly and a membrane attached to the frame; directing air through the three-way heat exchanger in an airflow direction, wherein the air flows through airflow gaps defined between adjacent panel assemblies; and Aerodynamic characteristics of the frame of the panel assembly are used to control the pressure drop of air flowing through the air flow gap in the air flow direction.

19. The method according to claim 18, wherein: Air is directed through the three-way heat exchanger at a velocity between 100 feet per minute and approximately 350 feet per minute.

20. The method of claim 18, further comprising maintaining a width of each air flow gap between 1 mm and 20 mm when directing air through the three-way heat exchanger.

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