Method of assembling multi-layer panel for use in heat exchanger

Abstract

A method of assembling a multi-layer panel for use in a heat exchanger is disclosed. An example method includes positioning a frame on a work platform, the frame having two header sections and an intermediate section, the intermediate section defining a heat transfer fluid region, and each header section defining a frame alignment feature; positioning a heat exchange sheet on the frame across the intermediate section and each header section, the heat exchange sheet having two sheet alignment features, each corresponding to one of the frame alignment features; inserting alignment pins of the work platform into each pair of corresponding frame alignment features and sheet alignment features; and welding the heat exchange sheet to the frame.

Description

Technical Field

[0001] This field generally relates to heating, ventilation, and air conditioning (HVAC) systems, and more particularly to systems and methods for assembling multi-layer panels (or panel assemblies) used in a three-way heat exchanger operable to transfer 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 handle the heating, cooling, and moisture removal of outside air circulated through an indoor space. The vapor compression cycle is widely used in HVAC systems to condition the temperature and humidity of outside air. Typically, outside air is cooled below its dew point temperature to allow moisture in the air to condense on 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 then reheated to a more comfortable temperature for the user. The process of over-cooling and reheating the air can become very energy-consuming and expensive.

[0003] In some applications, an HVAC system includes a vapor compression system used in combination with a liquid desiccant dehumidification system to remove moisture from outside air without cooling it below its dew point temperature. For example, an HVAC system can include a refrigerant subsystem operating under a vapor compression cycle and an air handling subsystem that uses a heat transfer fluid and a liquid desiccant to simultaneously absorb heat (sensible cooling) and moisture (latent cooling) from warm outside air to produce cooled and dehumidified indoor air. The air handling subsystem can include a three-way heat transfer device that facilitates sensible 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, a liquid desiccant and a heat transfer fluid are directed through the heat exchanger, and heat is transferred between the liquid desiccant and the heat transfer fluid. An 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 cycled 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, where 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 a panel that directs 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 panel and be distributed across respective flow channels in each panel. There is a continuing need to improve the design and / or manufacturability of the panel to facilitate cost reduction and / or optimize the operation and efficiency of the heat exchanger.

[0006] This Background of the Invention section is intended to introduce to the reader various aspects of the art that may be related to various aspects of the present disclosure, which are described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to 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 method of assembling a multi-layer panel for use in a heat exchanger, the method comprising: positioning a frame on a work platform, the frame having two header sections and an intermediate section, the intermediate section defining a heat transfer fluid region, and each header section defining a frame alignment feature; positioning a heat exchange sheet across the intermediate section and each header section on the frame, the heat exchange sheet having two sheet alignment features, each of the two sheet alignment features corresponding to one of the frame alignment features; inserting alignment pins of the work platform into each pair of corresponding frame alignment features and sheet alignment features; and welding the heat exchange sheet to the frame.

[0008] Another aspect is a method of assembling a multi-layer panel for use in a heat exchanger, the method comprising: positioning a frame on a work platform, the frame having two header sections and an intermediate section, the intermediate section defining a heat transfer fluid region, and each header section defining a header region; positioning a heat exchange sheet across the intermediate section and each header section on the frame; welding the heat exchange sheet to the frame to form an intermediate weld portion enclosing the heat transfer fluid region and two outer weld portions each enclosing one of the header regions in the header regions; and controlling alignment between the frame and the heat exchange sheet during welding.

[0009] On the other hand, there is a method of assembling a multi-layer panel for use in a heat exchanger, the method comprising: attaching a membrane to a heat exchange sheet, the heat exchange sheet including two series of orifices located at opposite ends of the heat exchange sheet, wherein the membrane extends across the two series of orifices such that a desiccant channel is defined between the membrane and the heat exchange sheet and is connected to each series of orifices; and attaching the heat exchange sheet with the attached membrane to a frame, the frame having two header sections and an intermediate section, the intermediate section defining a heat transfer fluid region and each header section defining a header region, wherein the desiccant channel is separated from the heat transfer fluid region by the heat exchange sheet and is connected to the header region through the two series of orifices.

[0010] There are various improvements to the features noted in the above aspects. Other features may also be incorporated into the above aspects. These improvements and additional features may exist alone or in any combination. For example, each of the features discussed below with respect to any of the illustrated embodiments may be incorporated alone or in any combination into any of the above aspects. 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 of the HVAC system, a front perspective view of a three-way heat exchanger.

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

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

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

[0016] Figure 6 is a left side elevation view of a 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 of the three-way heat exchanger, a right side elevation view of an example panel assembly.

[0018] Figure 8 is Figure 7 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 10F are, respectively Figure 8 enlarged views of portions A, B, C, D, E, and F shown in

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

[0022] Figure 12 is an example system that can be used to assemble Figure 7 a panel assembly

[0023] Figures 13 to 15 schematically depicts an operating sequence for assembling Figure 7 a panel assembly

[0024] Figure 16 is an example method of assembling Figures 13 to 15 a panel assembly according to an operating sequence Figure 7 in

[0025] Throughout the drawings, corresponding reference numerals indicate corresponding components DETAILED DESCRIPTION

[0026] Figure 1 is a schematic diagram of a heating, ventilation, and air conditioning (HVAC) system 100. The HVAC system 100 includes subsystems 102 to 106 and a liquid desiccant loop 108 that facilitate the heating, cooling, and moisture removal capabilities of the system 100. The subsystems of the HVAC system 100 include a refrigerant subsystem 102, a conditioner subsystem 104, and a regenerator subsystem 106. The conditioner subsystem 104 and the regenerator subsystem 106 can be used to process a first inlet air stream 110 and a second inlet air stream 114, respectively, and can be referred to herein as air handling subsystems 104 and 106. The HVAC system 100 can include additional components or other components in addition to those shown and described with reference to Figure 1 those shown and described

[0027] 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 exiting 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 the heat into the second inlet air stream 114 and directs the heated outlet air stream 116 to the atmosphere.

[0028] The refrigerant subsystem 102 includes an evaporator 118, a condenser 120, a compressor 122, and an expansion valve 124. The compressor 122 can be any suitable compressor, including but not limited to a scroll compressor, a reciprocating compressor, a rotary compressor, a screw compressor, and a centrifugal compressor. The expansion valve 124 can be any suitable expansion valve, such as a thermal expansion valve. The expansion valve 124 can alternatively be any suitable expansion device, such as an orifice or a capillary tube. The refrigerant subsystem 102 also includes a refrigerant loop 126 that circulates a working fluid, such as refrigerant, between the evaporator 118, the compressor 122, the condenser 120, and the expansion valve 124. The refrigerant subsystem 102 can include additional or other components in addition to those shown and described with reference to Figure 1 those shown and described.

[0029] In an example operation of the refrigerant subsystem 102, the refrigerant in the loop 126 is directed toward the compressor 122 as a low-pressure gaseous refrigerant 128. The compressor 122 compresses the gaseous refrigerant 128, which increases the temperature and pressure of the refrigerant. The pressurized high-temperature gaseous refrigerant 130 exits the compressor 122 and is directed toward the condenser 120, where the high-pressure gaseous refrigerant 130 is condensed into a high-pressure liquid refrigerant 132. The liquid refrigerant 132 exiting the condenser 120 is directed toward the expansion valve 124, which reduces the pressure of the liquid. The reduced-pressure fluid refrigerant 134, which can be a gas or a mixture of gas and liquid after passing through the expansion valve 124, is then directed toward the evaporator 118. The fluid refrigerant 134 evaporates into a gas in the evaporator 118 and thus exits the evaporator as a low-pressure gaseous refrigerant 128. The gaseous refrigerant 128 is then directed back to the compressor 122, where the gaseous refrigerant 128 is compressed again and the process repeats. The circulation of the refrigerant in the loop 126 can be driven by the compressor 122 and more specifically by the pressure difference that exists between the pressurized high-temperature gaseous refrigerant 130 exiting the compressor 122 and the low-pressure gaseous refrigerant 128 entering the compressor 122. AsFigure 1 As shown, the flow direction of the refrigerant through the loop 126 can be reversed to switch the heat transfer functions of the evaporator 118 and the condenser 120, and enable the HVAC system 100 to operate in various operating modes.

[0030] 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, ethylene glycol-based fluid, or any combination of water and ethylene glycol-based fluid) to and from the first three-way heat exchanger 136. The regulator subsystem 104 is engaged with the refrigerant subsystem 102 via the evaporator 118. In particular, the evaporator 118 is included in 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 the loop 138 to the fluid refrigerant 134 in the refrigerant loop 126. The regulator subsystem 104 may include additional or other components in addition to those shown and described with reference to Figure 1 the components shown and described. For example, the regulator subsystem 104 may include one or more pumps (not shown) that circulate the regulator heat transfer fluid in the loop 138 between the first three-way heat exchanger 136 and the evaporator 118. Suitable pumps that may be included in the regulator subsystem 104 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. Depending on the operating requirements of the HVAC system 100 and other factors (e.g., the temperature and / or humidity of the first air inlet stream 110), the regulator subsystem 104 may include additional heat transfer devices that transfer heat from the regulator heat transfer fluid to the atmosphere or transfer heat from the atmosphere to the regulator heat transfer fluid.

[0031] In an example operation of the regulator subsystem 104, the regulator heat transfer fluid in the loop 138 is directed towards the evaporator 118. The regulator heat transfer fluid is cooled in the evaporator 118 as heat is transferred from the regulator heat transfer fluid to the fluid refrigerant 134 in the loop 126 to produce gaseous refrigerant 128. The cooled regulator heat transfer fluid 140 leaving the evaporator 118 is directed towards and enters the first three-way heat exchanger 136. The first inlet air stream 110 is also directed through the first three-way heat exchanger 136. The first three-way heat exchanger 136 transfers heat from the first inlet air stream 110 to the regulator heat transfer fluid 140, thereby heating the regulator heat transfer fluid. The heated regulator heat transfer fluid 142 leaving the first three-way heat exchanger 136 is directed back to the evaporator 118, and the process is repeated.

[0032] The regenerator subsystem 106 includes a second three-way heat exchanger 144 and a regenerator heat transfer fluid loop 146 that circulates a regenerator heat transfer fluid (e.g., water, an ethylene glycol-based fluid, or any combination of water and an ethylene glycol-based fluid) to and from the second three-way heat exchanger 144. The regenerator subsystem 106 is engaged with the refrigerant subsystem 102 via the condenser 120. In particular, the condenser 120 is included in the refrigerant loop 126 and the regenerator heat transfer loop 146 and facilitates the transfer of heat from the pressurized gaseous refrigerant 130 in the refrigerant loop 126 to the regenerator heat transfer fluid. The regenerator subsystem 106 may include additional or other components in addition to those shown and described with reference to Figure 1 the components shown and described. For example, the regenerator subsystem 106 may include one or more pumps (not shown) that circulate the regenerator heat transfer fluid in loop 146 between the three-way heat exchanger 144 and the condenser 120. Suitable pumps that may be included in the regenerator subsystem 106 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. Depending on the operating requirements of the HVAC system 100 and other factors (e.g., the temperature and / or humidity of the first air inlet stream 110), the regenerator subsystem 106 may include additional heat transfer devices that transfer heat from the atmosphere to the regenerator heat transfer fluid or transfer heat from the regenerator heat transfer fluid to the atmosphere.

[0033] 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 gaseous refrigerant 130 in loop 126 to the regenerator heat transfer fluid to produce a liquid refrigerant 132. The heated regenerator heat transfer fluid 148 exiting the condenser is directed 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 to the second inlet air stream 114, thereby cooling the regenerator heat transfer fluid. The heated outlet air stream 116 exiting the second three-way heat exchanger 144 has a higher temperature than the second inlet air stream 114. The cooled regenerator heat transfer fluid 150 exiting the three-way heat exchanger 144 is directed back to the condenser 120, and the process is repeated.

[0034] The HVAC system 100 also includes a liquid desiccant loop 108 that operates in conjunction with subsystems 102 to 106 to condition 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 a first three-way heat exchanger 136 and a second three-way heat exchanger 144. Suitable liquid desiccants that can 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.

[0035] The liquid desiccant loop 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 can be included in the liquid desiccant loop 108 include, for example, centrifugal pumps, diaphragm pumps, positive displacement pumps, or any type of pump suitable for transferring liquids. The liquid desiccant loop 108 may include one or more pumps for transferring the liquid desiccant from the second heat exchanger 144 towards the first heat exchanger 136, and one or more pumps for transferring the diluted liquid desiccant 154 from the first heat exchanger 136 towards the second heat exchanger 144.

[0036] The concentrated liquid desiccant 152 in the liquid desiccant loop 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.

[0037] The diluted liquid desiccant 154 is directed towards the second three-way heat exchanger 144 of the regenerator subsystem 106, where the diluted liquid desiccant 154 discharges moisture into the second inlet air stream 114. The diluted liquid desiccant 154 cooperates with the heated regenerator heat transfer fluid 148 in the second three-way heat exchanger 144 to discharge heat and moisture into the second inlet air stream 114. Accordingly, the heated outlet air stream 116 exiting the second three-way heat exchanger 144 has a greater humidity and a higher temperature than the second inlet air stream 114. The liquid desiccant that has discharged moisture into the second inlet air stream 114 exits the regenerator subsystem 106 as the concentrated liquid desiccant 152. The concentrated liquid desiccant 152 exiting the second three-way heat exchanger 144 is directed back to the first three-way heat exchanger 136, and the process is repeated.

[0038] 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 those components shown and described.

[0039] Thus, in an example operating mode of the HVAC system 100, sensible cooling of the first inlet air stream 110 is facilitated by the first three-way heat exchanger 136 of the conditioner subsystem 104, which transfers heat from the inlet air stream 110 to the conditioner heat transfer fluid. The heat removed from the first inlet air stream 110 is then sequentially transferred 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 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.

[0040] The HVAC system 100 can operate in addition to the above with reference to Figure 1Operate in alternative operating modes other than the described exemplary operating modes. The exemplary operating modes of the HVAC system 100 described above can be considered as the warm weather operating mode of the HVAC system 100, in which the warm and humid air in the first inlet air stream 110 is cooled and dehumidified using the conditioner subsystem 104, and the heat and moisture removed are transferred by the subsystems 102 and 106 and the liquid desiccant loop 108 and discharged into the second inlet air stream 114 to produce a heated and humidified outlet air stream 116 that is directed to the warm and humid environment. In the cold weather operating mode of the HVAC system 100, the operation of the subsystems 102 to 106 and the liquid desiccant loop 108 can be reversed, such that the first three-way heat exchanger 136 heats and humidifies the cold and dry air in the first inlet air stream 110 to produce warm air with a comfortable humidity level in the outlet air stream 112 that is directed to the conditioned space. In the cold weather operating mode, the flow directions of the refrigerant in the loop 126 and the liquid desiccant in the liquid desiccant loop 108 can be reversed, such that the air handling subsystems 104 and 106 switch their respective functions, or the inlet vents and outlet vents for the first inlet air stream 110 and the second inlet air stream 114 can be rearranged and / or reconfigured such that the air flow directions through the first three-way heat exchanger 136 and the second three-way heat exchanger 144 are reversed, where the outlet air stream 112 is directed back to the surrounding environment and the outlet air stream 116 is directed towards the conditioned space. In other operating modes of the HVAC system 100, depending on the operating requirements and the desired set point temperature and humidity levels within the conditioned space, one of the air handling subsystems 104 and 106 can be idle or omitted from the HVAC system 100. For example, depending on the operating mode of the HVAC system 100, the air handling subsystem 106 can be omitted, and the refrigerant subsystem 104 can discharge or absorb heat from the refrigerant-air heat exchanger 120. In the case where the regenerator subsystem 106 is omitted or idle, the liquid desiccant circulating through the first three-way heat exchanger 136 in the liquid desiccant loop 108 can be regenerated or diluted using auxiliary regeneration equipment, dilution tanks, etc., depending on the operating mode of the HVAC system 100.

[0041] Still referring to Figure 1 , the first three-way heat exchanger 136 and the second three-way heat exchanger 144 have substantially the same configuration. In an alternative embodiment, the first three-way heat exchanger 136 and the second three-way heat exchanger 144 can have different configurations. Although the conditioner subsystem 104 and the regenerator subsystem 106 are in Figure 1are shown as including a three-way heat exchanger 136 and 144, respectively, but any suitable number of three-way heat exchangers 136 and 144 may be included in the respective subsystems 104 and 106. The number of three-way heat exchangers 136 included in the conditioner subsystem 104 may be the same as or different from the number of three-way heat exchangers 144 included in the regenerator subsystem 106. In the case where the conditioner subsystem 104 includes a plurality of three-way heat exchangers 136, the heat exchangers 136 may be operated in series, in parallel, or in any combination of series and parallel. In the case where the regenerator subsystem 106 includes a plurality of three-way heat exchangers 144, the heat exchangers 144 may be operated in series, in parallel, or in any combination of series and parallel.

[0042] 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.

[0043] 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.

[0044] 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 herein as the lateral axis, the Y-axis may also be referred to herein as the longitudinal axis, and the Z-axis may also be referred to herein as the vertical axis. The three-way heat exchanger 200 has opposite first lateral sides 202 and second lateral sides 204, first longitudinal sides 206 and second longitudinal sides 208, and first vertical sides 210 and second vertical sides 212, respectively. The first lateral side 202 and the second lateral side 204 are spaced apart in the lateral direction, the first longitudinal side 206 and the second longitudinal side 208 are spaced apart in the longitudinal direction, and the first vertical side 210 and the second vertical side 212 are spaced apart in the vertical direction. The directional terms are only used to describe the spatial relationship of the three-way heat exchanger 200 and the components of the heat exchanger. The examples shown and described are not limited to any specific orientation.

[0045] 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 below with reference to Figures 7 to 10F 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.

[0046] 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.

[0047] 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 gap 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, a liquid desiccant mist eliminator is described in U.S. Patent Application No. 18 / 391,384, filed on December 20, 2023, entitled "LIQUID DESICCANT AIR CONDITIONER MODULES HAVING A LIQUID DESICCANT MIST TRAP" (Docket No. 38902-391, COP-23-073US01), the entire disclosure of which is incorporated by reference.

[0048] 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.

[0049] Each of the end plates 218 and 220 includes alignment apertures 258 and 260 respectively for receiving a clamping assembly (not shown) for clamping the panel assemblies 214 together. Example clamping assemblies suitable for use in the three-way heat exchanger 200 are described in U.S. Patent Application No. 18 / 490,984, filed on October 20, 2023, the entire disclosure of which is incorporated herein by reference.

[0050] 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.

[0051] 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 through the three-way heat exchanger 200 in the longitudinal direction along the air flow direction (indicated by the arrow 278 in Figure 3 and Figure 5The 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.

[0052] The three-way heat exchanger 200 also includes a heat transfer fluid inlet 232, a heat transfer fluid outlet 234, 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, the heat transfer fluid outlet 234, the liquid desiccant inlet 236, and the liquid desiccant outlet 238 can vary according to the desired flow directions of the heat transfer fluid and the liquid desiccant through the panel assembly 214. The liquid desiccant inlet 236 and the heat transfer fluid outlet 234 can be defined (e.g., integrally formed therewith) by the end plate 218, and the liquid desiccant outlet 238 and the heat transfer fluid inlet 232 can be defined (e.g., integrally formed therewith) by the end plate 220. Alternatively, the heat transfer fluid inlet 232, the heat transfer fluid outlet 234, the liquid desiccant inlet 236, and the liquid desiccant outlet 238 can each be defined by a conduit (e.g., a pipe, tube, hose, or other suitable fluid conduit) extending longitudinally through an opening in the respective end plates 218 and 220.

[0053] 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 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 214 may include additional components, fewer components, or other components compared to the panel assembly 300.

[0054] 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-sectional line 9-9 in []. The spatial relationships of the components of the panel assembly 300 will be described with respect to the X, Y, and Z axes, as well as 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. 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.

[0055] The panel assembly 300 includes a frame 302 that defines a first vertical end 304 and a second vertical end 306 of the panel assembly 300 along the Z-axis, a first lateral face 305 and a second lateral face 307 along the X-axis, and a first longitudinal end 308 and a second longitudinal end 310 along the Y-axis. The frame 302 includes opposite first header sections 312 and second header sections 314 located at the first vertical end 304 and the second vertical end 306, respectively. The frame 302 further includes an intermediate section 316 between the opposite header sections 312 and 314. The header sections 312 and 314 define liquid desiccant header regions 320 and 322, respectively. The intermediate section 316 defines a heat transfer fluid region 324. The liquid desiccant header regions 320 and 322 are separated from the heat transfer fluid region 324 by portions 325, 327 (or "frame bars" 325, 327) 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 section 316 defines the leading edge and the trailing edge of the frame 302. The leading edge extends between the header sections 312, 314 near the first longitudinal end 308, and the trailing edge extends between the header sections 312, 314 near the second longitudinal end 310. The leading edge and / or the trailing edge may include aerodynamic features that facilitate controlling the pressure drop and / or reducing the resistance of the air flowing through the air flow gap 216. Exemplary aerodynamic features are described in U.S. Patent Application No. 18 / 390,941, filed on December 20, 2023, entitled "LIQUID DESICCANT AIR CONDITIONER MODULES HAVING AERODYNAMIC FEATURES" (Docket No. 38902-389, COP-24-003US01), the entire disclosure of which is incorporated herein by reference. Each header section 312, 314 of the frame 302 includes complementary air flow restrictor members (not labeled) that, when the heat exchanger 200 is assembled, mate or engage with the air flow restrictor members of an adjacent panel assembly 300 to form an air flow restrictor in the air flow gap 216 located between adjacent panel assemblies at opposite vertical ends.An airflow restrictor is described in U.S. Patent Application No. 18 / 390,948 (Docket No. 38902-390, COP-24-001US01) titled "LIQUID DESICCANTAIR CONDITIONER MODULES HAVING INTERLOCKING PANELS FOR CONTROLLING AIRFLOW" filed on December 20, 2023, the entire disclosure of which is incorporated herein by reference.

[0056] The panel assembly 300 also includes a first plate 326 and a second plate 328 disposed on opposite lateral faces of the frame 302 that cover an intermediate section 316 of the frame 302. The first plate 326 and the second plate 328 are sheets of material, for example, 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 in U.S. Patent No. 11,022,330 issued on June 1, 2021, and U.S. Patent No. 10,921,001 issued on February 16, 2021, the entire disclosure of each of these two U.S. patents being incorporated herein by reference. Referring below to Figures 12 to 16 Further describes exemplary systems and methods for attaching the plates 326 and 328 to the frame 302.

[0057] The frame 302 and the plates 326 and 328 can be made of different but compatible materials for welding together. For example, the frame 302 and the plates 326 and 328 can each be made of the same or different thermoplastic or polymeric materials. The materials for the frame 302 and the plates 326 and 328 can also be selected based on their compatibility with the liquid desiccant used in the three-way heat exchanger 200. Suitable polymeric materials for the frame 302 and the plates 326 and 328 include, for example, polyolefins (e.g., polypropylene and / or polyethylene), acrylonitrile butadiene styrene (ABS), and combinations thereof. The frame 302 and the plates 326, 328 can be made of the same or compatible materials to enable attachment (e.g., welding) of the frame and the plates. The frame 302 and / or 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. For example, the frame 302 and / or the plates 326, 328 can include a suitable amount of carbon black to facilitate absorption of laser energy and laser welding of the plates and the frame. Additionally and / or alternatively, the frame 302 and / or the plates 326, 328 can include electrically conductive fiber additives to facilitate radio frequency welding. 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.

[0058] 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 between the plates 326 and 328 through the heat transfer fluid passage 330, and the liquid desiccant flows on the outer surfaces of the plates 326 and 328 opposite the heat transfer fluid passage 330. The plates 326 and 328 isolate the liquid desiccant from the heat transfer fluid in the passage 330 and allow heat to be transferred between the liquid desiccant and the heat transfer fluid. The plates 326 and 328 can extend over one or both of the liquid desiccant manifold regions 320 and 322 and define openings (e.g., orifices 360) that are aligned with one or both of the liquid desiccant manifold regions 320 and 322 to enable the liquid desiccant to flow therethrough. In an exemplary panel assembly 300, each of the plates 326 and 328 includes a series of orifices 360 positioned adjacent the liquid desiccant manifold 320 and a series of orifices 362 positioned adjacent 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.

[0059] A mesh or perforation (not shown) may 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 may also promote a more constant flow rate of the heat transfer fluid through the passage 330. The mesh or perforation may also help to 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 may also provide turbulence of the heat transfer fluid to increase heat transfer with the liquid desiccant flowing over the outer surfaces of the sheets or plates 326 and 328. A variety of materials may be used for the mesh or perforation. For example, the mesh or perforation may comprise the same polymeric material as the plates (e.g., polyolefin, ABS, or a combination thereof). Alternatively, flow guides (not shown) may 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.

[0060] 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 may 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.

[0061] Membranes 332 and 334 are respectively attached to one of the lateral faces 305 and 307 of the frame 302 to encapsulate and seal the liquid desiccant manifold regions 320 and 322. Membranes 332 and 334 can additionally and / or alternatively be attached to the outer surfaces of the respective sheets or plates 326 and 328, which can help maintain the width of the liquid desiccant channels 336 and 338 and / or limit the tendency of membranes 332 and 334 to bulge outward 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 directly attached to plates 326 and 328 respectively by heat sealing or welding, where compatible materials (e.g., polyolefins) are used for membranes 332 and 334 and the respective plates 326 and 328. An outer adhesive layer (not shown) can be applied to the outer surfaces of plates 326 and 328 to improve the quality or ease of forming a heat seal or weld with the respective membranes 332 and 334. The outer surfaces of plates 326 and 328 can include raised patterns or dot features (not shown) to which membranes 332 and 334 adhere, heat seal, or otherwise attach. The raised patterns can be formed on the frame 302 and / or plates 326 and 328 by thermoforming, embossing, or other suitable techniques. Attaching membranes 332 and 334 to the dot features or raised patterns can provide the additional advantage of promoting uniform distribution of the liquid desiccant across the liquid desiccant channels 336 and 338 in the longitudinal direction and reducing stresses that can cause warping of plates 326 and 328. Warping of 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 membranes 332 and 334 during an exemplary operation of the three-way heat exchanger 200. Additional details regarding attaching membranes 332 and 334 to the frame 302 and the respective plates 326 and 328 are described in U.S. Patent No. 11,022,330, issued June 1, 2021, and U.S. Patent No. 10,921,001, issued February 16, 2021, the entire disclosure of each of which is hereby incorporated by reference herein. Reference is made below to Figures 12 to 16 Exemplary systems and methods for attaching membranes 332 and 334 to the frame 302 and the respective sheets or plates 326 and 328 are further described.

[0062] 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 in structure and 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 through the membranes 332 and 334 or desorb water into the air flowing through the membranes 332 and 334. The membranes 332 and 334 can be made of a translucent material such as a translucent thermoplastic or polymer (e.g., polypropylene) having a suitable laser transmissivity such that the frames 302 and the plates 326, 328 can be laser welded when the respective membranes 332, 334 are attached (e.g., heat sealed) to the plates without forming a weld between the membrane and the plate.

[0063] The frame 302 defines a liquid desiccant inlet port 340 for supplying liquid desiccant into the liquid desiccant header region 320 and a liquid desiccant outlet port 342 for receiving liquid desiccant from the liquid desiccant header 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 header section 312 and is positioned adjacent to the liquid desiccant header 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 header section 314 and is positioned adjacent to the liquid desiccant header region 322 and the first longitudinal end 308 at the second vertical end 306 of the panel assembly 300. Thus, the first corner flange 364 and the second corner flange 366 and the liquid desiccant inlet port 340 and the liquid desiccant outlet port 342 defined therein are located on opposite longitudinal and vertical ends of the panel assembly 300.

[0064] 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 header region 320 of the panel assembly 300, flows through each of the liquid desiccant channels 336 and 338 and into the liquid desiccant header 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 header region 320, 322 the liquid desiccant is supplied to and from which header region the liquid desiccant exits.

[0065] The frame 302 also defines a heat transfer fluid inlet port 346 for supplying heat transfer fluid to the heat transfer fluid passage 330 and a heat transfer fluid outlet port 348 for receiving heat transfer fluid from the heat transfer fluid passage 330. The heat transfer fluid inlet port 346 is defined in the third corner flange 368 of the frame 302. The third corner flange 368 of the frame 302 is part of the second header section 314 and the intermediate section 316. The third corner flange 368 is positioned adjacent to the heat transfer fluid passage 330 at the second longitudinal end 310 of the panel assembly 300 and near the second vertical end 306. The heat transfer fluid outlet port 348 is defined in the fourth corner flange 370 of the frame 302. The fourth corner flange 370 is part of the first header section 312 and the intermediate section 316. The fourth corner flange 370 is positioned adjacent to the heat transfer fluid passage 330 at the first longitudinal end 308 of the panel assembly 300 and near the first vertical end 304. Thus, the third corner flange 368 and the fourth corner flange 370 and the heat transfer fluid inlet port 346 and the heat transfer fluid outlet port 348 defined therein are located on opposite longitudinal ends and vertical ends of the panel assembly 300. Additionally, the first corner flange 364 and the fourth corner flange 370 and the liquid desiccant inlet port 340 and the heat transfer fluid outlet port 348 defined therein are all positioned near the first vertical end 304 on opposite longitudinal ends of the panel assembly. The second corner flange 366 and the third corner flange 368 and the liquid desiccant outlet port 342 and the heat transfer fluid inlet port 346 defined therein are all positioned near the second vertical end 306 on opposite longitudinal ends of the panel assembly.

[0066] As represented by Figure 7 and Figure 9 the flow line 350 in, in an exemplary operation of the three-way heat exchanger 200, heat transfer fluid is supplied via the heat transfer fluid inlet port 346 to the heat transfer fluid passage 330 of the panel assembly 300, flows 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 ports 346, 348 the heat transfer fluid enters the passage 330 through and which port the heat transfer fluid exits the passage 330 through.

[0067] Figures 10A to 10D are respectively Figure 8An enlarged view of portions A, B, C, and D of the frame 302 shown, and more particularly depicts corner flanges 364 to 370. In particular, Figures 10A to 10D Microchannels or orifices are shown that provide fluid connections between ports 340, 342, 346, and 348 defined in the panel assembly 300 and the corresponding fluid regions. As Figure 10A and Figure 10B shown, the heat transfer fluid inlet port 346 is connected to the heat transfer fluid region 324 through the orifice 352 ( Figure 10B ), and the heat transfer fluid outlet port 348 is connected to the heat transfer fluid region 324 through the orifice 354 ( Figure 10A ). The heat transfer fluid region 324 defines a heat transfer fluid channel 330 when sealed to opposite lateral faces 305 and 307 of the frame 302 by plates 326 and 328. As indicated by the flow lines 350 in Figure 10A and Figure 10B , the heat transfer fluid enters the heat transfer fluid channel 330 from the inlet port 346 via the orifice 352 and exits the channel 330 via the orifice 354 into the outlet port 348.

[0068] As Figure 10C and Figure 10D shown, the liquid desiccant inlet port 340 is connected to the first liquid desiccant header region 320 through the orifice 356 ( Figure 10C ), and the liquid desiccant outlet port 342 is connected to the second liquid desiccant header region 322 through the orifice 358 ( Figure 10D ). As indicated by the flow lines 344 in Figure 10C and Figure 10D , the liquid desiccant enters the first liquid desiccant header 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 header region 322, and exits the header region 322 via the orifice 358 into the outlet port 342. In the example illustrated in Figures 10A to 10D , each of the orifices 352 to 358 includes two orifices. Any suitable number of orifices may be used for the orifices 352 to 358. In some examples, a greater number of orifices may be used for some of the orifices 352 to 358 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 and size and shape of the orifices used for each of the orifices 352 to 358 may also vary between panel assemblies 300.

[0069] Figures 10A to 10DAlso shown are exemplary features of the panel assembly 300 that can 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 - 370 of the frames 302 of adjacent panel assemblies 300 can be connected. As shown, each of the corner flanges 364 - 370 includes one or more snap fittings 372. The snap fittings 372 extend from a first lateral face 305 of the frame 302 in a lateral direction, and corresponding holes 374 ( Figure 6 shown in) penetrate into a second lateral face 307 at a position laterally opposite to the snap fittings 372. In the illustrated example, each of the corner flanges 364 - 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 - 370. The corner flanges 364 - 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 - 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 - 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 - 370 of the frame 302 of the laterally adjacent panel assembly 300 to directly connect the adjacent panel assemblies 300.

[0070] Each of the corner flanges 364 - 370 further includes one or more alignment holes 376 extending therethrough in the lateral direction. In the illustrated embodiment, the corner flanges 364 - 370 each include two alignment holes 376, which are 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 located longitudinally inside the second alignment hole 376b and adjacent to the corresponding corner of the heat transfer fluid region 324. In other examples, more or fewer alignment holes 376 may be included at the corner flanges 364 - 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 apertures 258 of the first end plate 218 and one of the alignment apertures 260 of the second end plate 220 ( Figure 2 and Figure 4as shown). The second alignment hole 376b receives a corresponding clamping assembly (not shown). The second alignment hole 376b does not correspond to the alignment orifices 258 and 260 in the end plates 218 and 220 such that the clamping assembly received by the second alignment hole 376b extends through the panel assembly 300 but does not extend through the end plates 218 and 220.

[0071] Still referring to Figures 10A to 10D , each of the corner flanges 364 to 370 includes a flange collar 378 surrounding a respective fluid port 340, 342, 346, 348 defined in the corner flange. The flange collar 378 extends in a lateral direction from the first lateral face 305 of the frame 302. Each corner flange 364 to 370 also includes a corresponding slotted nozzle 380 that projects into the second lateral face 307 and surrounds the respective fluid ports 340, 342, 346, 348 at a position laterally opposite 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 in the panel assemblies 300 is received by one of the corresponding slotted nozzles 380 of the corner flanges 364 to 370 of the frame 302 of 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 slotted nozzle 380 and insertion of the flange collar 378 into the slotted nozzle 380. The guide teeth 382 may include guiding features (e.g., chamfers) for easier insertion of the teeth and the flange collar 378 into the corresponding slotted nozzle 380. An elastomeric seal (not shown), such as an O-ring, may be seated within each of the slotted nozzles 380 and 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 slotted nozzle 380.

[0072] Figure 10E and Figure 10F are, respectively, Figure 8 enlarged views of portions E and F of the frame 302 in Figure 13corresponds to that shown). The alignment features 388 of the frame 302 ("frame alignment features") are positioned near the first vertical end 304 and the second vertical end 306. One of the frame alignment features 388 is located vertically above the manifold region 320, and the other frame alignment feature 388 is located vertically below the manifold region 322. Each frame alignment feature 388 is also located at the longitudinal center of the frame 302. As Figure 13 shown, when each plate 326, 328 is positioned on the frame 302, the alignment features 389 of each sheet or plate 326, 328 ("sheet alignment features") are located at the vertical and longitudinal positions of the plate, and the vertical and longitudinal positions of the plate correspond to the vertical and longitudinal positions of the frame alignment feature 388. The paired corresponding frame alignment features 388 and sheet alignment features 389 facilitate aligning each plate 326, 328 to the frame 302 when the plate is attached to the frame. Each frame alignment feature 388 includes an alignment hole 390, which corresponds to the alignment hole 391 of the corresponding sheet alignment feature 389 ( Figure 13 ). The corresponding alignment holes 390, 391 can receive alignment pins of the workstation (e.g., Figure 12 the alignment pin 406 of the welding system 400 shown) to maintain alignment and limit movement between the frame 302 and the plate 326 or 328 when the plate is attached to the frame. The frame alignment features 388 and the sheet alignment features 389 can also be "flexible" and include corresponding flexure portions 392, 393, which facilitate controlling the alignment, tension, and tolerance stack-up between the frame 302 and the plate 326 or 328 when the plate is attached to the frame, as described in more detail below.

[0073] Also referring to Figure 3 and Figure 5 and showing a left view of the 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, panels 326 and 328 and membranes 332 and 334 are omitted. When assembled and installed in the tee heat exchanger 200, for each pair of adjacent panel assemblies 300, the membrane 332 of one panel assembly in the panel assemblies 300 faces the membrane 334 of the other panel assembly in the panel assemblies 300. An air flow gap 216 is defined between the adjacent membranes 332 and 334. Each panel assembly 300 may have a reduced width at the intermediate section 316 such that the panel assemblies 300 are spaced apart at their adjacent intermediate sections 316 to define the air flow gap 216. Additionally and / or alternatively, the air flow gap 216 may be defined and maintained by supports or spacers 386 between the intermediate sections 316 of the adjacent panel assemblies 300. The supports or spacers 386 extend outwardly in the lateral direction from the intermediate sections 316 near the longitudinal ends 308 and 310. The intermediate section 316 of each frame 302 may additionally and / or alternatively include snap fittings 372 and corresponding holes 374 near the longitudinal ends 308 and 310 (as Figure 6 and Figure 7 shown). The snap fittings 372 and corresponding holes 374 located on the intermediate section 316 of the frame 302 may facilitate connecting adjacent panel assemblies 300 at 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.

[0074] The panel assemblies 300 are arranged in the tee heat exchanger 200 such that for each panel assembly, the first lateral face 305 and the second lateral face 307 of the frame 302 are respectively oriented towards the first lateral side 202 and the second lateral side 204 of the tee heat exchanger 200. The first longitudinal end 308 and the second longitudinal end 310 are respectively located at the first longitudinal side 206 and the second longitudinal side 208 of the tee heat exchanger 200, and the first vertical end 304 and the second vertical end 306 are respectively located at the first vertical side 210 and the second vertical side 212 of the tee heat exchanger 200.

[0075] The ports 340, 342, 346, and 348 of the panel assembly 300 are aligned to define respective manifolds of the three-way heat exchanger 200 that extend in a lateral direction, through which heat transfer fluid and liquid desiccant flow into and out of the panel assembly 300 between the first lateral side 202 and the second lateral side 204. The liquid desiccant inlet port 340 of the panel assembly 300 is aligned to form a liquid desiccant inlet manifold 242 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the first vertical side 210 and the second longitudinal side 208 of the three-way heat exchanger 200. The liquid desiccant outlet port 342 of the panel assembly 300 is aligned to form a liquid desiccant outlet manifold 244 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the second vertical side 212 and the first longitudinal side 206 of the three-way heat exchanger 200. The heat transfer fluid inlet port 346 of the panel assembly 300 is aligned to form a heat transfer fluid inlet manifold 246 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the second vertical side 212 and the second longitudinal side 208 of the three-way heat exchanger 200. The heat transfer fluid outlet port 348 of the panel assembly 300 is aligned to form a heat transfer fluid outlet manifold 248 that extends between the first lateral side 202 and the second lateral side 204 adjacent to the first vertical side 210 and the first longitudinal side 206 of the three-way heat exchanger 200.

[0076] The panel assembly 300 may include O-rings or other elastomeric seal members that form 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 slotted nozzles 380, and when the flange collar 378 is inserted into the slotted nozzle 380, a fluid-tight seal is formed at the adjacent fluid ports 340, 342, 346, 348 between 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, corresponding holes 374, and alignment holes 376 collectively 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.

[0077] As Figure 3 and Figure 5As shown in, conduits 250, 252, 254, and 256 are used to fluidly connect the heat transfer fluid inlet 232 and outlet 234, as well as 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 leave the three-way heat exchanger 200. The liquid desiccant inlet 236 is fluidly connected to the liquid desiccant inlet manifold 242 through conduit 250. The liquid desiccant outlet 238 is fluidly connected to the liquid desiccant outlet manifold 244 through conduit 252. The heat transfer fluid inlet 232 is fluidly connected to the heat transfer fluid inlet manifold 246 through conduit 254. The heat transfer fluid outlet 234 is fluidly connected to the heat transfer fluid outlet manifold 248 through conduit 256. Conduits 250 through 256 can include any suitable fluid conduits (rigid and / or flexible) that enable the heat transfer fluid and the liquid desiccant to flow between the respective inlets and outlets and the manifolds, including, for example but not limited to, pipes, hoses, tubes, and combinations thereof. Each of conduits 250 through 256 can be attached to the respective manifolds 242 through 248 by coupling the end of the conduit to an appropriate one of the ports 340, 342, 346, and 348 in the port plate assembly 300 (i.e., the port plate assembly 300 adjacent to the lateral sides 202 or 204). Conduits 250 through 256 can be attached to the appropriate ports 340, 342, 346, and 348 of the port plate assembly 300 using any suitable means - including fasteners, threads, clamps, etc.

[0078] Conduits 250 and 256 extend between the end plate 218 and the port plate assembly 300 at the first lateral side 202. Conduits 252 and 254 extend between the end plate 220 and the port plate assembly 300 at the second lateral side 204. Conduits 250 and 256 can extend through the end plate 218 to respectively define the inlet 236 or the outlet 234, can be coupled to the respective inlet 236 or outlet 234 defined by the end plate 218, or can be integrally formed with the end plate 218 and the respective inlet 236 or outlet 234 defined by the end plate 218. Conduits 252 and 254 can extend through the end plate 220 to respectively define the outlet 238 or the inlet 232, can be coupled to the respective outlet 238 or inlet 232 defined by the end plate 220, or can be integrally formed with the end plate 220 and the respective outlet 238 or inlet 232 defined by the end plate 220.

[0079] Each of manifolds 242 to 248 may be closed at a lateral side 202 or 204 of the heat exchanger 200 opposite the inlet or outlet to which the manifold is connected. The liquid desiccant inlet manifold 242 may be closed at the second lateral side 204, the liquid desiccant outlet manifold 244 may be closed at the first lateral side 202 opposite the liquid desiccant inlet manifold 242, the heat transfer fluid inlet manifold 246 may be closed at the first lateral side 202, and the heat transfer fluid outlet manifold 248 may be closed at the second lateral side 204 opposite the heat transfer fluid inlet manifold 246. Manifolds 242 to 248 may be closed at the respective lateral sides 202 or 204 by end plates 218 or 220 ( Figure 2 and Figure 4 as shown). In particular, the end plate 218 may block ports 342 and 346 of the panel assembly 300 at an end of the panel assembly 300 adjacent to the first lateral side 202 to close manifolds 244 and 246 at the first lateral side 202. The end plate 220 may block ports 340 and 348 of the panel assembly 300 at an end of the panel assembly 300 adjacent to the second lateral side 204 to close manifolds 244 and 246 at the second lateral side 204. Additionally and / or alternatively, end caps or plugs 272 and 274 (see Figure 11 ) may be inserted into or otherwise disposed over ports 342 and 346 of the panel assembly 300 adjacent to the first lateral side 202 to close manifolds 244 and 246 at the first lateral side 202, and end caps or plugs 270 and 276 (see Figure 11 ) may be inserted into or otherwise disposed over ports 340 and 348 of the panel assembly 300 adjacent to the second lateral side 204 to close manifolds 244 and 246 at the second lateral side 204.

[0080] Now referring to Figure 11 , the operation of the three-way heat exchanger 200 will now be described. Figure 11 is a schematic view showing an internal view of the three-way heat exchanger 200 to depict the flow of liquid desiccant and heat transfer fluid through manifolds 242 to 248 and the panel assembly 300. In the schematic view of Figure 11 , for ease of illustration and description, the panel assembly 300 is depicted as having exaggerated and / or simplified features.

[0081] In an exemplary operation of the heat exchanger 200, an inlet air flow (e.g., Figure 1The first inlet air stream 110 or the second inlet air stream 114) shown enters via the air stream inlet 224 and flows in the air stream direction 278 through the air gap 216 defined between adjacent panel assemblies 300. The air flowing through the air gap 216 is directed through the liquid desiccant indicated by the flow line 344 and the heat transfer fluid indicated by the flow line 350 of each panel assembly in 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 from Figure 1 the regulator heat transfer fluid of the regulator subsystem 104 shown in, and the heat exchanger 200 is used to cool and dehumidify the air flowing through the air gap 216. In other operations, the liquid desiccant 344 is the diluted liquid desiccant 154 from the liquid desiccant loop 108, and the heat transfer fluid 350 is from Figure 1 the regenerator heat transfer fluid of the regenerator subsystem 106 shown in, and the heat exchanger 200 is used to heat the moisture and discharge the moisture into the air flowing through the air gap 216.

[0082] The liquid desiccant 344 flows from the first side side 202 to the liquid desiccant inlet manifold 242 via the liquid desiccant inlet 236 and the conduit 250 ( Figures 3 to 5 shown in). The liquid desiccant 344 enters the liquid desiccant header region 320 of each panel assembly 300 from the liquid desiccant inlet manifold 242 via the orifice 356. In each panel assembly 300, the liquid desiccant 344 flows from the liquid desiccant header region 320, enters the liquid desiccant channels 336 and 338 via the orifices 360 ( Figure 7 and Figure 8 shown in) on each of the plates 326 and 328, flows downward through the liquid desiccant channels 336 and 338, and enters the liquid desiccant header region 322 via the orifices 362 ( Figure 7 and Figure 8 shown in) on each of the plates 326 and 328. When the liquid desiccant 344 flows behind the membranes 332 and 334 of the panel assembly 300, the liquid desiccant 344 absorbs moisture from the air flowing through the air gap 216 adjacent to the membranes 332 and 334 or desorbs water into the air. Permitting moisture to permeate through each of the membranes 332 and 334 such that moisture can be transferred 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 corresponding liquid desiccant header region 322 and flows towards the second side side 204 through the liquid desiccant outlet manifold 244. The liquid desiccant 344 flows via the conduit 252 and the liquid desiccant outlet 238 ( Figure 5exits the heat exchanger 200 as shown in

[0083] The heat transfer fluid 350 flows from the second lateral side 204 into the heat transfer fluid inlet manifold 246 via the heat transfer fluid inlet 232 and conduit 254 ( Figure 4 and Figure 5 as shown in ). The heat transfer fluid 350 enters each panel assembly 300 from the heat transfer fluid inlet manifold 246 via the orifice 352. In each panel assembly 300, the heat transfer fluid 350 flows upward through the heat transfer fluid channels 330. The heat transfer fluid 350 flowing through the channels 330 is in thermal communication with the liquid desiccant 344 flowing through the liquid desiccant channels 336 and 338. Depending on the operating mode of the heat exchanger 200, heat is transferred between the heat transfer fluid 350 and the liquid desiccant 344 to remove heat from the air flowing through the air gap 216 or discharge heat into the air flowing through the air gap 216. The heat transfer fluid 350 that has absorbed or discharged heat exits each panel assembly 300 via the orifice 354 and flows toward the first lateral side 202 through the heat transfer fluid outlet manifold 248. The heat transfer fluid 350 exits the heat exchanger 200 via the conduit 256 and the heat transfer fluid outlet 234 ( Figures 3 to 5 as shown in ).

[0084] In the illustrated embodiment, the flow directions of the heat transfer fluid 350 and the liquid desiccant 344 are shown by way of example only and may be varied in other embodiments of the heat exchanger 200. For example, the liquid desiccant 344 may flow upward through the desiccant channels 336 and 338 on the panel assembly 300. In these examples, the directions 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 they may flow through the panel assembly in the same direction.

[0085] Now referring to Figures 12 to 16 , an exemplary system and method for assembling one or more panel assemblies 300 (also referred to as multi-layer panels) will now be described. Figure 12is a schematic view of an exemplary system 400 that can be used to attach each plate 326, 328 (also referred to as heat exchange sheet 326, 328 or sheet 326, 328) to the frame 302 and / or attach each membrane 332, 334 to the corresponding sheet 326, 328. The welding system 400 includes a working chamber 402 and a working platform 404 positioned within the chamber 402. The working platform 404 is sized and shaped to support the frame 302, plates 326, 328, and membranes 332, 334. The working platform 404 includes two alignment pins 406 that are sized, shaped, and positioned on the working platform to be inserted into two pairs of corresponding frame alignment features 388 ( Figure 10E and Figure 10F ) and sheet alignment features 389 ( Figure 13 ). Figure 12 Schematically depicted is the frame 302 positioned on the working platform 404 and the heat exchange sheet 326 or 328 positioned on the frame, where the alignment pins 406 extend through the corresponding frame alignment features 388 and sheet alignment features 389. In particular, each alignment pin 406 extends through the alignment holes 390 of the corresponding pair of frames 302 and the alignment holes 391 of the sheet 326 or 328. When the system 400 is used to attach (e.g., weld) the sheet 326 or 328 to the frame 302, inserting the alignment pins 406 through the pairs of corresponding alignment holes 390, 391 operates to maintain alignment and restrict relative movement between the frame 302 and the sheet 326 or 328.

[0086] In Figure 12In the example illustrated, one of the sheets 326 or 328 with a film 332 or 334 pre - attached thereto is positioned on the lateral faces 305 and 307 of the frame 302 for attaching the sheet 326 or 328 to the frame 302. This is merely an example of an exemplary method of assembling the panel assembly 300 using the system 400. In other methods, the frame 302 may have the sheet 326 or 328 positioned thereon without the film 332 or 334 pre - attached to the sheet. The system 400 can additionally and / or alternatively be used to attach (e.g., heat - seal) the film 332 or 334 to the sheet 326 or 328 before attaching the sheet 326 or 328 to the frame 302. In such a method, the sheet 326 or 328 can be positioned on the work platform 404, where the alignment pins 406 extend through the alignment holes 391, and the film 332 or 334 is positioned across the sheet 326 or 328 between the alignment holes 391 without inserting the alignment pins 406 through the film 332 or 334. In some examples, the film 332 or 334 may also include alignment features corresponding to the sheet alignment features 388 for inserting the alignment pins therethrough. The system 400 can be used to attach (e.g., weld) two sheets 326 and 328, with or without their respective previously attached films 332 and 334, to the frame 302. In such a method, the first sheet 326 or 328 is attached to the frame 302, where the first sheet 326 or 328 is positioned on the frame 302, as Figure 12 shown, and the second sheet 328 or 326 is attached to the frame 302, where the frame 302 is flipped (i.e., rotated 180° about a vertical axis extending between the vertical ends 304 and 306) such that the previously attached first sheet 326 or 328 (and optionally, the film 332 or 334) is sandwiched between the frame and the work platform 404, and the second sheet 328 or 326 is positioned on the other lateral face 307 or 305 of the frame 302. The alignment pins 406 can extend through the alignment holes 388 of the frame 302 and the alignment holes 389 of each of the sheets 326 and 328 respectively positioned on the lateral faces 305 and 307 of the frame 302.

[0087] Referring Figures 10E to 10F and Figure 13 , the frame alignment features 388 and the sheet alignment features 389 are flexible and include respective flexure portions 392, 393 that facilitate controlling the alignment, tension, and tolerance stack - up between the frame 302 and the sheet 326 or 328 when the panel is attached to the frame. The flexure portions 392, 393 allow the respective alignment holes 390, 391 to move or flex. The flexure portion 392 of the frame 302 ( Figure 10E and Figure 10F) Each is formed by two cuts 394, the two cuts 394 being located above and below the corresponding alignment holes 390 and defining a "bow tie" shape. The flexure 392 formed by the two cuts 394 is the filament in which the alignment holes 390 are defined and allows the alignment holes to move or flex within the two cuts 394. The flexures 393 of sheets 326 and 328 ( Figure 13 ) Each is formed by two slits 395 located on each side of the alignment hole 391. The flexure 393 formed by the two slits 395 is a flexible region radiating outward from the alignment hole 391 that allows the alignment hole 391 to move or flex.

[0088] Referring Figure 12 , system 400 also includes an attachment tool 408 (e.g., a laser welder or heat sealer) positioned in chamber 402 in an operable manner. Tool 408 includes a working element 410 (e.g., a heater or laser) connected to a support 412. Support 412 is connected to an arm 414 (or arms 414) of tool 408, and arm 414 is operative to move support 412 and working element 410 relative to work platform 404 within chamber 402. Movement of arm 414 can be facilitated by any suitable means such as a linear actuator, motor, hydraulic cylinder, pneumatic cylinder, etc. Movement of arm 414 controls the movement of support 412 and working element 410 for attaching sheets 326 and 328 to frame 302 and / or for attaching membranes 332 and 334 to corresponding sheets 326 and 328. In exemplary system 400, arm 414 can be operative to move support 412 and working element 410 downward toward work platform 404 and upward away from work platform 404. Arm 414 can additionally and / or alternatively move support 412 and working element 410 in another direction. In some examples, arm 414 can be operative for multi-axis movement. Work platform 404 can additionally and / or alternatively be operatively coupled to one or more actuators (e.g., linear actuators, motors, hydraulic cylinders, pneumatic cylinders, etc.) for controlling movement of work platform 404 relative to support 412 and working element 410 along a single axis or multiple axes.

[0089] Working element 410 (e.g., a heater or laser) can be operative to form a suitable seam or pattern for attaching (e.g., welding) sheets 326 and 328 to frame 302 and / or for attaching (e.g., heat sealing) membranes 332 and 334 to corresponding sheets 326 and 328. Figure 14 An exemplary heat seal pattern between membrane 332 or 334 and sheet 326 or 328 is shown in Figure 15An exemplary welding pattern between the sheet 326 or 328 and the frame 302 is shown. Attaching the sheets 326 and 328 to the frame 302 can be performed using the same tool 408 as is used for attaching the membranes 332 and 334 to the respective sheets 326 and 328, or different tools 408 can be used for these operations. In the case of using different tools 408, the different tools 408 can operate in the same or different chambers 402. Suitably, the working element 410 of each tool 408 can be operated to form welds and / or heat seals in a single operation. In other words, the working element 410 of the tool 408 (e.g., a laser welder or a heat sealer) can "punch" or "impress" the weld or heat seal in a single simultaneous stroke, rather than tracing the welding pattern or forming the heat seal separately. Forming the weld or heat seal in a single operation can significantly reduce the time and cost associated with attaching the membranes 332, 334 to the sheets 326, 328 and / or attaching the sheets 326, 328 to the frame 302. The alignment holes 390 and 391 and the flexures 392 and 393 can facilitate the precise alignment and proper tensioning of the frame 302 and the sheets 326 and 328 such that welds or heat seals can be formed in the described single operation.

[0090] The system 400 further includes a controller 416 communicatively coupled to the attachment tool 408 and configured to control the operation of the tool 408 (e.g., by controlling the operation of the arm 414 and / or the working element 410). For example, the controller 416 can be configured to control the operation of the arm 414 to move the support 412 and the working element 410 toward and away from the work platform 404. The controller 416 can additionally and / or alternatively be configured to control the operation of the working element 410 to form a suitable welding or heat seal pattern depending on whether the tool 408 is used to perform a welding operation to attach the sheets 326 and 328 to the frame 302 and / or attach the membranes 332 and 334 to the respective sheets 326 and 328.

[0091] The controller 416 may include any suitable computer and / or other processing unit, including any suitable combination of computers, processing units and / or the like that can be communicatively connected to each other and can operate independently or in association with each other (for example, the controller 416 can form all or part of a controller network). The controller 416 may include one or more modules or devices, which are enclosed in a single housing, or can be located away from each other. The controller 416 may include one or more processors and associated storage devices configured to perform various computer-implemented functions (for example, performing the functions disclosed herein). As used herein, the term "processor" refers not only to integrated circuits, but also to controllers, microcontrollers, microcomputers, programmable logic controllers (PLCs), application-specific integrated circuits and other programmable circuits. In addition, the storage device of the controller 416 may be a storage element or include a storage element, which includes but is not limited to a computer-readable medium (for example, a random access memory (RAM)), a computer-readable non-volatile medium (for example, a flash memory), a floppy disk, a compact disk read-only memory (CD-ROM), a magneto-optical disk (MOD), a digital versatile disk (DVD) and / or other suitable storage elements. Such a storage device may be configured to store suitable computer-readable instructions that, when executed by a processor, are configured to cause or render the controller 416 to perform the various functions described herein, including, but not limited to, controlling the tool 408 .

[0092] The controller 416 can communicate with one or more components of the tool 408 via a communication interface communicatively coupled to one or more of these devices. The communication interface can include, but is not limited to, a wired network adapter, a wireless network adapter, a mobile telecommunications adapter, a serial communication adapter, or a parallel communication adapter. The communication interface can receive data signals from one or more remote devices, such as the tool 408, or transmit data signals to one or more remote devices, such as the tool 408. The controller 416 can also include a presentation interface coupled to one or more of the processors in the processor. The presentation interface can present information, such as a user interface, to an operator of the system 400. In one embodiment, the presentation interface includes a display adapter (not shown) coupled to a display device (not shown) such as a cathode ray tube (CRT), a liquid crystal display (LCD), an organic light emitting diode (OLED) display, or an "electronic ink" display. In some embodiments, the presentation interface includes one or more display devices. Additionally or alternatively, the presentation interface includes an audio output device (not shown), such as, but not limited to, an audio adapter, a speaker, or a printer (not shown). The controller 416 can also include a user input interface coupled to one or more of the processors in the processor and operable to receive input from an operator. The user input interface can include, for example, but is not limited to, a keyboard, a pointing device, a mouse, a stylus, one or more input buttons, a touch-sensitive panel such as, but not limited to, a touchpad or a touch screen, and / or an audio input interface such as, but not limited to, a microphone. A single component, such as a touch screen, can serve as both a display device for the presentation interface and the user input interface.

[0093] Figures 13 to 15 Illustrates operations that can be performed to assemble the multi-layer panel 300 in accordance with Figure 16 the method 500 shown in Figure 7 ). The method 500 can be performed using one or more systems (e.g., Figure 12 one or more of the systems 400 shown in Figure 13 is a schematic view of the heat exchange sheets 326, 328 included in the panel assembly 300. Figure 14 is a schematic view of the films 332, 334 attached to Figure 13 the sheet 326 or 328. Figure 15 is a schematic view of the sheets 326, 328, wherein Figure 14 the films 332, 334 of Figures 13 to 15 are attached to the frame 302 in the operation sequence shown in Figure 16Method 500 is provided by way of example only, and the operations described may be performed in any suitable order. For example, sheets 326 or 328 may be attached to frame 302 before attaching membranes 332 or 334 to sheets 326 or 328. This operation may also be repeated for heat exchange sheets 326 and 328 and membranes 332 and 334 to assemble multi-layer panel 300, which includes two sheets 326 and 328 and two membranes 332, 334, with one sheet 326, 328 attached to each lateral face 305, 307 of frame 302, and one membrane 332, 334 attached to each sheet 326, 328.

[0094] Method 500 includes providing 502 Figure 13 the heat exchange sheets 326, 328 shown, the heat exchange sheets 326, 328 including two alignment features 389 and two series of apertures 360, 362. The two series of apertures 360, 362 are located between the two alignment features 389. One alignment feature 389 is positioned adjacent each vertical end of sheets 326, 328 (relative to Figure 13 the orientation shown). One series of apertures 360 is positioned near the "top" alignment feature 389, and one series of apertures 362 is positioned near the "bottom" alignment feature 389.

[0095] Method 500 further includes positioning 504 the heat exchange sheets 326, 328 on a work platform (e.g., Figure 12 work platform 404 of ) such that two alignment pins (e.g., alignment pins 406) are inserted through two alignment holes 391 of the heat exchange sheets 326, 328. Method 500 further includes attaching (e.g., heat-sealing) 506 membranes 332, 334 to the heat exchange sheets 326, 328 positioned on the work platform such that desiccant channels 336, 338 ( Figure 9 ) are defined between the membranes 332, 334 and the sheets 326, 328. As Figure 14 shown, membranes 332, 334 are less in height than sheets 326, 328 and are positioned on the sheets such that the membranes overlap the two series of apertures 360, 362 and the alignment features 389 are not covered by the membranes. In this example, membranes 332, 334 do not include alignment features corresponding to the alignment features 389 of sheets 326, 328. Membranes 332, 334 may be positioned and aligned on the sheets by visual inspection such that apertures 360, 362 are sufficiently overlapped by the membranes and the alignment features 389 remain uncovered. In other examples, membranes 332, 334 may include alignment features to facilitate centering the membranes on sheets 326, 328.

[0096] Attaching the membranes 332, 334 to the heat exchange sheets 326, 328, 506 can be performed using a heat sealing tool (e.g., tool 408), which is operated to heat seal the membranes to the sheets along various "heat seal portions" (e.g., lines, seams, patterns), as Figure 14 shown. In the illustrated example, two heat seal lines 418, 420 are formed adjacent to two series of orifices 360, 362, respectively, such that the desiccant channels 336, 338 are connected to the two series of orifices 360, 362 and are sealed above the vertical of orifice 360 and below the vertical of orifice 362. Each heat seal line 418, 420 includes arcs complementary to the orifices 360, 362, respectively, and a horizontal (longitudinal) section connecting each arc.

[0097] Each orifice 360, 362 is centered within the respective arc of the heat seal lines 418, 420, which provides space for desiccant to flow through each orifice 360, 362 between the sheets 326, 328 and the membranes 332, 334. Misalignment between the orifices 360, 362 and the heat seal lines 418, 420 can cause the orifice 360 and / or 362 to be too close to the heat seal line 418 and / or 420 or to be partially covered by the heat seal line 418 and / or 420, which is disadvantageous because it restricts or impedes the flow of desiccant through the desiccant channels 336, 338, increases the tensile stress in the membranes 332, 334, and / or otherwise negatively affects the performance of the panel assembly 300. Thus, in one example of heat sealing, alignment features 389 of the heat exchange sheets 326, 328 are used to control the alignment between the heat seal lines 418, 420 and a series of orifices 360, 362, and more specifically, to control the centering of the orifices within the arcs of the heat seal lines. That is, alignment pins 406 inserted into alignment holes 391 of the sheets 326, 328 are operated to control the alignment between the sheets and the heat sealing tool to ensure that the arcs of the heat seal lines 418, 420 and the corresponding orifices 360, 362 remain centered.

[0098] When positioned on the work platform, the flexure 393 can also be operative to control the alignment between the sheets 326, 328 and the heat-sealing tool and the tension within the sheets. Specifically, the flexure 393 compensates for dimensional variations (e.g., height variations) of the sheets 326, 328, which may be caused, for example, by manufacturing tolerances and result in a change in the vertical spacing between the alignment holes 391. The likelihood of such a change can be exacerbated or altered depending on, for example, the material used for the sheets 326, 328. For example, thermoplastic or polymeric materials (e.g., polyolefins such as polypropylene and / or polyethylene) that may be used to manufacture the sheets 326, 328 can exhibit large dimensional variations. Such variations can result in undesired tension or stress on the sheets 326, 328 when the sheets 326, 328 are positioned on the work platform 404 and the alignment pins 406 are inserted into the alignment holes 391, and the undesired tension or stress can cause deformation (e.g., bending or stretching) of the sheets 326, 328 and misalignment between the sheets 326, 328 and the heat-sealing tool. The flexure 393 enables the alignment holes 391 to flex, which facilitates reducing the negative impact that manufacturing tolerances may have on the alignment between the sheets 326, 328 and the heat-sealing tool by reducing or eliminating any deformation of the sheets in areas that require precise alignment with the heat-sealing tool (e.g., near a series of orifices 360, 362).

[0099] Figure 14Additional heat seals that can be formed between the sheets 326, 328 and the membranes 332, 334 are shown. For example, heat seal “scratches” 422, 424 can be formed at opposite vertical ends of the membranes 332, 334. Heat seal scratch 422 is formed above the heat seal line 418, and heat seal scratch 424 is formed below the heat seal line 420. The heat seal scratches 422, 424 can facilitate holding the “excess” portions of the membranes 332, 334 above and below the heat seal lines 418, 420, respectively. The heat seal scratches 422, 424 can also facilitate increasing the reliability of the attachment between the membranes 332, 334 and the sheets 326, 328. The scratches 422, 424 can be formed at longitudinal positions corresponding to the longitudinal positions of the arcs of the heat seal lines 418, 420. Discrete heat seals or heat seal “dots” 426 can also be formed between the heat seal line 418 and the heat seal line 420. The heat seal dots 426 can define discrete flow paths for desiccant flowing between the sheets 326, 328 and the membranes 332, 334. Any suitable number and / or arrangement of heat seal dots 426 can be implemented. The number and / or position of the heat seal dots 426 can be selected to facilitate controlling the distribution and / or flow rate of desiccant through the desiccant channels 336, 338. Additional details regarding suitable patterns for the heat seal dots 426 are described in U.S. Patent No. 10,921,001, issued on February 16, 2021, the entire content of which is incorporated by reference.

[0100] As described above, a heat seal tool (e.g., tool 408) can be operated to heat seal the membranes 332, 334 to the heat exchange sheets 326, 328 in a single heat seal operation such that the heat seal tool stamps or imprints each of the heat seals (e.g., heat seal lines 418, 420, heat seal scratches 422, 424, and heat seal dots 426) in one stroke. This requires precise alignment between the heat seal tool and the sheets 326, 328 to ensure that the heat seals are not misaligned with the apertures 360, 362. Appropriately, the flexible alignment features 389 of the sheets 326, 328 operate to control the alignment, tension, tolerances, and movement of the sheets relative to the platform and the heat seal tool when the alignment pins 406 of the work platform 404 are inserted therein such that the heat seal can be performed in a single operation.

[0101] Referring Figure 16 , method 500 further includes positioning 508 the frame 302 on a work platform (e.g., Figure 12On the working platform 404), the working platform can be the same working platform on which the heat exchange sheets 326, 328 are positioned 504 before attaching the membranes 332, 334 to the sheet, or it can be a different working platform. The frame 302 is positioned 508 on the working platform 404 such that two alignment pins (e.g., alignment pin 406) are inserted through two alignment holes 390 ( Figure 10E and Figure 10F ) of the frame 302. The method 500 further includes positioning 510 the heat exchange sheets 326, 328 on the frame 302. The sheets 326, 328 are positioned 510 on the frame 302 such that the sheets extend across the intermediate section 316 and the header sections 312 and 314 of the frame, and such that the sheet alignment features 389 are aligned with the corresponding frame alignment features 388 (as Figure 15 shown). The alignment pins 406 inserted through the two alignment holes 390 of the frame 302 are also inserted through the corresponding alignment holes 391 of the sheets 326, 328 positioned 510 on the frame 302 to facilitate controlling the alignment between the sheets and the frame and restricting the relative movement between them.

[0102] The method 500 further includes attaching (e.g., laser welding) 512 the sheets 326, 328 to the frame 302. After attaching 506 the membranes 332, 334 to the sheets, or before the membranes are attached 506, the heat exchange sheets 326, 328 can be positioned 510 on the frame 302 and attached 512 to the frame 302. Attaching 512 the sheets 326, 328 to the frame 302 can be performed using a laser welding tool (e.g., tool 408), which is operated to laser weld the sheets to the frame along various "welds" (e.g., paths or seams) as Figure 15 shown. In the illustrated example, the sheets 326, 328 are attached to the intermediate section 316 of the frame 302 along an intermediate weld 428, to the first header section 312 of the frame along a first outer weld 430 (or "top" weld), and to the second header section 314 of the frame along a second outer weld 432 (or "bottom" weld). The intermediate weld 428 encapsulates and seals the sheets 326, 328 around the heat transfer fluid region 324 defined by the frame 302. The top weld 430 encapsulates and seals the sheets 326, 328 around the first liquid desiccant header region 320 defined by the frame 302. The bottom weld 432 encapsulates and seals the sheets 326, 328 around the second liquid desiccant header region 322 defined by the frame 302. The heat transfer fluid region 324 and the liquid desiccant header regions 320, 322 are, for example, in Figure 8shown. A series of orifices 360 in sheets 326, 328 are encapsulated by top welds 430 and aligned with the liquid desiccant header region 320, and a series of orifices 362 in the sheets are encapsulated by bottom welds 432 and aligned with the liquid desiccant header region 322. The orifices 360, 362 connect the desiccant channels 336, 338 defined between membranes 332, 334 and sheets 326, 328 to the liquid desiccant header regions 320, 322, and the regions of the sheets located between the orifices 360, 362 and sealed to the intermediate section 316 by the intermediate weld 428 separate the desiccant channels from the heat transfer fluid region 324. The welds 428, 430, and 432 also operate to restrict heat transfer fluid flow into the liquid desiccant header regions 320, 322 and to restrict liquid desiccant flow into the heat transfer fluid region 324 or the channel 330 (as Figure 9 shown).

[0103] As Figure 15 shown, the heat seals (e.g., heat seal lines 418, 420, heat seal score lines 422, 424, and heat seal dots 426) for attaching membranes 332, 334 to sheets 326, 328 have minimal overlap with the welds 428, 430, 432 for attaching the sheets to the frame 302. The heat seal line 418 and the heat seal score line 422 are substantially surrounded by the top weld 430, the heat seal dot 426 is substantially surrounded by the intermediate weld 428, and the heat seal line 420 and the heat seal score line 424 are substantially surrounded by the bottom weld 428. This can suitably minimize the energy applied to the membranes 332, 334 and the sheets 326, 328 when assembling the multi-layer panel 300. The welds 428, 430, and 432 can also be formed substantially only between the sheets 326, 328 and the frame 302 to reduce or eliminate the welds formed with the membranes 332, 334. Figure 15 The internal weld portions of the welds 428, 430, 432 (i.e., the portions of the welds covered by the membranes 332, 334) are depicted in dashed lines. In the illustrated example, the internal weld portions of the welds 428, 430, 432 are located on the frame bars 325, 327 ( Figure 8 shown) of the frame 302, which separate the heat transfer fluid region 324 from the liquid desiccant header regions 320, 322, respectively. The internal weld portions of the welds 428, 430, 432 can be formed only between the sheets 326, 328 and the frame 302. This can prevent welds from being formed below the orifices 360 and / or above the orifices 362 and extending across the desiccant channels 336, 338 between the membranes 332, 334 and the sheets 326, 328, which could otherwise restrict or impede the flow of liquid desiccant in the desiccant channels 336, 338 between the header region 320 and the header region 332.

[0104] As described above, the membranes 332, 334 can be made of a translucent material such as a translucent thermoplastic or polymer (e.g., polypropylene) that has a suitable laser transmittance such that light emitted from a laser (e.g., the working element 410) can pass therethrough. The sheets 326, 328 can also be made of a translucent thermoplastic or polymer having a laser transmittance. The laser transmittance of the membranes 332, 334 and / or the frames 326, 328 can be additionally and / or alternatively facilitated using a translucent coating (e.g., oil) that can subsequently be removed after welding. The frame 302 can include a laser absorbing additive (e.g., carbon black) that enables the frame to absorb light emitted from the laser, heating and melting the frame at a suitable location such that when the frame cools and solidifies, the welds 428, 430, and 432 are formed. Additionally and / or alternatively, the frame 302 can be made of a laser absorbing thermoplastic or polymer. The translucent membranes 332, 334 and the sheets 326, 328 enable the frame 302 and the sheets to be laser welded in the case where the membranes 332, 334 are attached (e.g., heat sealed) to the plate without forming a weld between the membranes and the sheets. The laser (e.g., the working element 410) can be operated to emit light at a suitable wavelength selected based on the transmittance of the translucent membranes 332, 334 and the sheets 326, 328 and the laser absorbing ability of the frame 302.

[0105] Inserting the alignment pins 406 through the pairs of corresponding frame alignment features 388 and sheet alignment features 389 when positioning 510 the sheets 326, 328 on the frame 302 and attaching 512 them to the frame 302 suitably facilitates controlling the alignment of the sheets and the frame and prevents "mis-welding". In particular, the pairs of corresponding frame alignment features 388 and sheet alignment features 389 into which the alignment pins 406 are inserted ensure that the welds 428, 430, and 432 are suitably shaped to seal the sheets 326, 328 around the heat transfer fluid region 324 and the liquid desiccant manifold regions 320, 322, thereby preventing the flow of heat transfer fluid into the desiccant channels 336, 338 and / or the flow of liquid desiccant into the heat transfer fluid channel 330. Controlling the alignment between the sheets 326, 328 and the frame 302 also suitably facilitates ensuring that the orifices 360, 362 are correctly aligned with the liquid desiccant manifold regions 320, 322, respectively, and that there is a minimum overlap between the welds for attaching 512 the sheets to the frame and the heat seals for attaching 506 the membranes 332, 334 to the sheets.

[0106] When positioned on the work platform, the frame flexure 392 and the sheet flexure 393 can also be operative to control the alignment between the sheets 326, 328, the frame 302, and the laser welding tool, as well as the tension in the sheets and the frame. As described above, the sheet flexure 393 ( Figure 13 ) compensates for dimensional variations (e.g., height variations) in the sheets 326, 328 that may be caused by manufacturing tolerances and result in variations in the vertical spacing between the alignment holes 391. The frame flexure 392 ( Figure 10E and Figure 10F ) is also operative to compensate for dimensional variations (e.g., height variations) in the frame 302 that may be caused by manufacturing tolerances and result in variations in the vertical spacing between the alignment holes 390. As described above, for example, when thermoplastic or polymeric materials (e.g., polyolefins such as polypropylene and / or polyethylene) are used to manufacture the sheets 326, 328 and / or the frame 302, the tendency for such variations may be exacerbated. The sheet flexure 392 and the frame flexure 393 allow the respective alignment holes 390, 391 to flex, which facilitates reducing the negative impact that manufacturing tolerances may have on the alignment between the sheets 326, 328, the frame 302, and the laser welding tool by reducing or eliminating any deformation (e.g., bending or stretching) in the sheets and the frame in the areas that need to be precisely aligned with the laser welding tool. Additionally, the frame flexure 392 and the sheet flexure 393 operate independently (i.e., allow the respective alignment holes 390, 391 to flex independently of the other alignment hole 391, 390) to facilitate controlling the tolerance stack-up between the dimensional variations of the frame and the sheets.

[0107] The laser welding tool (e.g., tool 408) can be operative to weld the sheets 326, 328 to the frame 302 in a single welding operation such that the laser welding tool forms, punches, or imprints each of the welds 428, 430, 432 in one simultaneous stroke. This requires precise alignment between the laser welding tool, the sheets 326, 328, and the frame 302 to ensure that the welds are not misaligned. Appropriately, the alignment pins 406 of the work platform 404, which are inserted through their corresponding pairs of flexible frame alignment features 388 and sheet alignment features 389, are operative to control the alignment, tension, tolerance stack-up, and movement between the frame 302, the sheets 326, 328, and the laser welding tool such that the laser welding can be performed in a single operation.

[0108] The example systems and methods described include assembling a multi-layer panel adapted for use in a three-way heat exchanger that removes heat and moisture from and / or discharges heat and moisture into an air stream. The example multi-layer panel includes 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 manufacturability and assemblability of the multi-layer panel are improved by flexible alignment features of the frame and sheets that facilitate controlling alignment and manufacturing tolerances when attaching the membranes to the respective sheets and when attaching the sheets to the frame. The flexible alignment features enable precise alignment, which facilitates attaching the membranes to the sheets using a single operation and attaching the sheets to the frame using a single operation. Heat seals are advantageously formed between the membranes and the respective sheets to facilitate controlling the flow and / or distribution of liquid desiccant through the desiccant passage. Welds are advantageously formed between the sheets and the frame to prevent the flow of heat transfer fluid and liquid desiccant in undesired areas of the multi-layer panel. The heat seals and welds are also appropriately positioned to minimize overlap between the heat seals and welds and to minimize the energy applied to the sheets and membranes.

[0109] 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 may be used independently and separately from other components described herein. For example, the systems and methods described herein may be used in systems other than HVAC systems.

[0110] When introducing elements of the present disclosure or embodiments of the present disclosure, the articles "a", "an", "the", and "said" are intended to mean that there is one or more of the elements. The terms "comprising", "including", "containing", and "having" are intended to be inclusive and mean that 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 convenience of description and does not require any particular orientation of the item being described.

[0111] 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.

[0112] Since various changes may be made to the above-described construction and method without departing from the scope of the present disclosure, all matter contained in the above description and shown in the accompanying drawings should be interpreted as illustrative and not in a limiting sense.

Claims

1. A method of assembling a multilayer panel for use in a heat exchanger, the method comprising: positioning a frame on a work platform, the frame having two header sections and a middle section, the middle section defining a heat transfer fluid area, and each header section defining a frame alignment feature; positioning a heat exchange sheet on the frame across the middle section and each of the header sections, the heat exchange sheet having two sheet alignment features that each correspond to one of the frame alignment features; inserting an alignment pin of the work platform into each corresponding pair of frame alignment features and sheet alignment features; as well as The heat exchanging sheets are welded to the frame.

2. The method according to claim 1, wherein: Each header section of the frame defines a header area, and the heat exchange sheet has two series of holes, each of which is positioned adjacent to one of the sheet alignment features, wherein positioning the heat exchange sheet on the frame includes aligning each series of holes with one of the header areas.

3. The method according to claim 2, wherein: Welding the heat exchange sheet to the frame comprises forming an intermediate weld enclosing the heat transfer fluid area, the intermediate weld being located between the two series of orifices.

4. The method according to claim 3, wherein: Welding the heat exchange sheet to the frame includes forming the middle weld and two outer welds, each outer weld enclosing the header area and one of the corresponding series of apertures.

5. The method according to claim 4, wherein: Welding the heat exchanging sheet to the frame includes forming the middle weld and the two outer welds in a single welding operation.

6. The method according to claim 2, wherein: Inserting the alignment pins of the work platform into each corresponding pair of frame and sheet alignment features operates to control alignment between each series of apertures and corresponding header regions during welding.

7. The method of claim 2, further comprising attaching a membrane to the heat exchange sheet.

8. The method according to claim 7, wherein: Attaching the membrane to the heat exchanging sheet is performed before welding the heat exchanging sheet to the frame.

9. The method according to claim 7, wherein: Attaching the membrane to the heat exchange sheet includes forming a heat seal line adjacent each series of apertures to define a desiccant channel extending between and connected to the two series of apertures.

10. The method according to claim 9, wherein: Attaching the membrane to the heat exchange sheet further comprises forming a discrete heat seal between the two series of apertures.

11. The method according to claim 10, wherein: The heat seal line and the discrete heat seals are formed in a single heat sealing operation.

12. The method of claim 1 further comprising controlling a tolerance stack-up between the frame and the heat exchange sheet using flexures located at pairs of corresponding frame and sheet alignment features.

13. A method of assembling a multi-layer panel for use in a heat exchanger, the method comprising: positioning a frame on a work platform, the frame having two header sections and a middle section, the middle section defining a heat transfer fluid region, and each header section defining a header region; positioning heat exchange sheets on the frame across the middle section and each of the header sections; welding the heat exchange sheet to the frame to form a middle weld enclosing the heat transfer fluid area and two outer welds each enclosing one of the header areas; as well as Alignment between the frame and the heat exchanging sheets is controlled during welding.

14. The method according to claim 13, wherein: Controlling alignment between the frame and the heat exchange sheet during welding includes inserting alignment pins of the work platform through corresponding alignment features of the frame and the heat exchange sheet when positioning the heat exchange sheet on the frame.

15. The method of claim 14, further comprising controlling a tolerance stack-up between the frame and the heat exchange sheet using flexures at corresponding alignment features of the frame and the heat exchange sheet.

16. The method according to claim 13, wherein: The heat exchange sheet has two series of apertures, each of the two series of apertures being aligned with one of the header areas of the frame, wherein the method further comprises attaching a membrane to the heat exchange sheet to define a desiccant channel connected to the two header areas through the two series of apertures.

17. The method according to claim 16, wherein: Attaching the membrane to the heat exchange sheet includes heat sealing the membrane to the heat exchange sheet to form a heat seal line adjacent to each series of orifices, and wherein the method further includes using a flexible alignment feature of the heat exchange sheet to control the alignment between the heat seal line and the series of orifices during heat sealing.

18. A method of assembling a multi-layer panel for use in a heat exchanger, the method comprising: attaching a membrane to a heat exchange sheet comprising two series of apertures at opposite ends of the heat exchange sheet, wherein the membrane extends across the two series of apertures such that a desiccant channel is defined between the membrane and the heat exchange sheet and is connected to each series of apertures; and The heat exchange sheet with the membrane attached is attached to a frame having two header sections and a middle section, the middle section defining a heat transfer fluid area, and each header section defining a header area, wherein the desiccant channels are separated from the heat transfer fluid area by the heat exchange sheet and connected to the header area through the two series of orifices.

19. The method according to claim 18, wherein: Attaching the heat exchange sheet with the membrane attached to the frame includes controlling alignment and tolerance stack-up between the frame and the heat exchange sheet using flexible alignment features of the frame and the heat exchange sheet.

20. The method according to claim 18, wherein: Attaching the membrane to the heat exchange sheet includes heat sealing the membrane to the heat exchange sheet to form a heat seal line adjacent each series of apertures, wherein during heat sealing, a flexible alignment feature of the heat exchange sheet is used to control alignment between the heat seal line and the series of apertures.

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