Patent Publication Number: US-11041654-B2

Title: Air handling unit

Description:
RELATED APPLICATIONS 
     This application claims priority to U.S. patent application Ser. No. 15/886,743, filed on Feb. 1, 2018, the entirety of which is hereby incorporated by reference. 
     BACKGROUND 
     Portable shelters have been developed for transportation to remote sites where they are then set-up for use. For instance, among other applications, portable shelters may be used as barracks, field hospitals, mess halls, kitchens, relief shelters, communication centers, or laboratories. When deployed, in some instances, walls of the portable shelter may extend to create a significantly larger operating footprint than when the portable shelter is transported. 
     To accommodate for their range of different environments and purposes, portable shelters may have air-conditioners, heaters, or other air handling units (AHUs). However, these units are not easily integrated into portable shelters and often consume large amounts of space. Given the compact nature of portable shelters, these units can therefore detract from their utility. 
     In addition, depending on the application of the portable shelter or per certain regulations and/or requirements, the interior air within the portable shelter may need to be cycled or exchanged with outside air. However, exchanging interior air with outside air causes heat transfer between the interior and exterior of the portable shelter. Such heat transfer between the interior and exterior of the portable shelter is undesirable because it impairs the ability of the heater or air conditioner to control the temperature of the portable shelter. This results in a need for larger capacity heaters, air conditioners, or environmental control units (ECUs), which translates to higher energy demands required by the shelter. Also, in the military context, such heat transfer between the interior and exterior of the portable shelter is undesirable because it may make the portable shelter detectible by thermal imaging. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The detailed description is described with reference to the accompanying figures. In the figures, the left-most digit(s) of a reference number identifies the figure in which the reference number first appears. The same reference numbers in different figures indicate similar or identical items. 
         FIG. 1  is a perspective view of an exterior of an example portable shelter in which an example air handling unit is installed. 
         FIG. 2  is a perspective view of an interior of the example portable shelter of  FIG. 1 , showing the example air handling unit disposed on either side of a door of the portable shelter. 
         FIG. 3  is a cross-sectional view of the example portable shelter of  FIG. 1 , showing the example air handling unit of  FIG. 2  coupled and disposed through a wall of the portable shelter. 
         FIG. 4  is a perspective view of a panel included in a heat exchanger of the example air handling unit of  FIG. 2 . 
         FIG. 5  is a perspective exploded view of the heat exchanger included in the example air handling unit of  FIG. 2 . 
         FIG. 6A  is a first perspective view of the heat exchanger included in the example air handling unit of  FIG. 2 . 
         FIG. 6B  is a second perspective view of the heat exchanger of  FIG. 6A  included in the example air handling unit of  FIG. 2 . 
         FIG. 7  is a side view of the heat exchanger of  FIG. 6A . 
         FIG. 8  is an end view of the heat exchanger of  FIG. 6A . 
         FIG. 9  is a perspective view of a cover of the example air handling unit of  FIG. 2 . 
         FIG. 10A  is a partial exploded perspective view of the example air handling unit of  FIG. 2 . 
         FIG. 10B  is a partial perspective view of the example air handling unit of  FIG. 2 . 
         FIG. 10C  is a partial perspective view of the example air handling unit of  FIG. 2 . 
         FIG. 11  is a perspective view of the example air handling unit of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION 
     As mentioned above, existing portable shelters, or other portable shelters, may include heaters and/or air conditioners to regulate temperature within the portable shelters. Additionally, air within the portable shelters (i.e., interior air) may need to be cycled or exchanged with outside air. However, if there is a temperature differential between the interior air and the outside air, exchanging the interior air with outside air causes heat transfer between the interior and exterior of the of the portable shelter. A heat exchanger may be used to minimize heat transfer between the interior and exterior of the shelter. However, heat exchangers or air handling units are primarily designed for buildings and often require large amounts of ductwork. As such, conventional heat exchangers or air handling units are not practical for use in portable shelters because their size significantly reduces the operational space within the portable shelter. While the size of the heat exchanger may be reduced, for instance, doing so reduces efficiency and/or heat transfer capacity of the heat exchanger. 
     Consequently, existing portable shelters have not effectively integrated air handling units without sacrificing an operational space of the portable shelter or an efficiency of the air handling unit. For instance, an air handling unit having an efficient heat exchanger that captures and transfers heat from exhausted interior air (i.e., outgoing air) to incoming outside ambient air (i.e., incoming air) may be large in size, reduce an interior space of the portable shelter, or increase an exterior footprint of the portable shelter. 
     On the other hand, limiting the size of the heat exchanger within the air handling unit may reduce its effects on the operational space but may sacrifice an efficiency of the heat exchanger, thereby limiting its heat transfer ability (e.g., the rate at which the heat exchanger can transfer heat between the interior and exterior air) and/or requiring increased energy consumption to heat and/or cool the interior space. Due to the remoteness and harshness of some environments in which portable shelters may be deployed, its often desirable to minimize the amount of power consumed by the portable shelter. 
     In light of the shortcomings of existing portable shelters, this application describes compact air handling units that may be used with portable shelters. In some instances, the air handling unit may have a minimal impact on the operational space of the portable shelter while at the same time efficiently transferring heat between outgoing interior air and incoming exterior air. That is, the air handling unit may serve to heat or cool the incoming air through exchanging heat with outgoing air from within the portable shelter. In doing so, less power may be demanded to condition the interior space of the portable shelter. 
     In some instances, the air handling unit may include fans, a heat exchanger, and a cover. The fans may be arranged or oriented to exhaust interior air and draw exterior air through the heat exchanger. For instance, a first fan (or fans) may draw incoming air (e.g., pulling or pushing the ambient air) towards the interior of the portable shelter while a second fan (or fans) may draw outgoing air (e.g., pulling or pushing the interior air) towards the exterior of the portable shelter. Therefore, the fans may create separate air flows or streams through the heat exchanger in opposite directions. That is, a first flow may represent an incoming air flow, from the exterior toward the interior of the portable shelter, while a second flow may represent an outgoing air flow, from the interior toward the exterior of the portable shelter. 
     In some instances, the fans may draw the respective air flows through the heat exchanger to condition the incoming air before reaching the interior space of the portable shelter. As such, heat may be exchanged between the outgoing air flow and the incoming air flow within the heat exchanger to cool or warm the incoming air exhausted into the interior space of the portable shelter. Within the heat exchanger, between where the incoming air enters the heat exchanger and the outgoing air exits the heat exchanger, the incoming air may exchange heat with the outgoing air, vice versa. 
     Within the heat exchanger, the incoming air flow and the outgoing air flow may be designed to exchange heat between panels, plates, or dividers interposed between the incoming air flow and the outgoing air flow. For instance, in some examples, the incoming air may be warmer than the outgoing air, such as in a desert environment, and the interior of the portable shelter may need to be kept at cooler temperatures. However, simply exhausting the outgoing air without capturing otherwise lost energy may require continuously cooling the interior of the portable shelter (e.g., via an air-conditioner), thereby requiring more energy for the air conditioner to cool the interior of the portable shelter. By exchanging heat with outgoing air, the incoming air may be cooled prior to being exhausted into the portable shelter. 
     Conversely, in a cold environment, heat may be transferred from the outgoing air to the incoming air to maintain a warm environment within the interior of the portable shelter. As such, the power consumption of a heater or other heating ventilation and air conditioning (HVAC) equipment used to heat and/or cool the interior of the portable shelter may be reduced. 
     In some instances, the heat exchanger may include a plurality of first inlets for receiving the incoming air and a plurality of first outlets for exhausting the incoming air into the interior of the portable shelter. The heat exchanger may also include a plurality of second inlets for receiving the outgoing air and a plurality of second outlets for exhausting the outgoing air. In some instances, the plurality of first inlets may be coplanar or aligned with one another, the plurality of first outlets may be coplanar or aligned with one another, the plurality of second inlets may be coplanar or aligned with one another, and the plurality of second outlets may be coplanar or aligned with one another. In addition, in some instances, the plurality of first inlets may be parallel or perpendicular to the plurality of second inlets and the plurality of first outlets may be parallel or perpendicular with the plurality of second outlets. 
     Interposed between the plurality of first inlets and the plurality of first outlets may be a plurality of first channels configured to route or direct the incoming air towards the interior of the portable shelter. Similarly, interposed between the plurality of second inlets and the plurality of second outlets may be a plurality of second channels that route or direct the outgoing air towards the exterior of the portable shelter. In some instances, the plurality of first channels and the plurality of second channels may be alternatively positioned or stacked to form the heat exchanger of the air handling unit. 
     The plurality of first inlets may be disposed adjacent to an opening in the portable shelter to receive incoming air drawn by a fan(s). To exhaust the outgoing air, the plurality of second outlets may also be disposed adjacent to an opening in the portable shelter. In some instances, the opening in the portable shelter through which the incoming air enters the plurality of first inlets may be adjacent to or displaced from the opening in the portable shelter where the outgoing air exits the plurality of second outlets. As such, the plurality of first inlets may draw incoming air at a location distant to where the outgoing air exits the plurality of second outlets. In some instances, this may prevent outgoing air from immediately being drawn back into the portable shelter. 
     In some instances, a shroud or other vent may be included that directs the outgoing air away from a location at which the incoming air is drawn into the air handling unit and/or the heat exchanger. Additionally, or alternatively, other ductwork or conduit may be included that permits the incoming air to be drawn at a location distant from the outgoing air. 
     As alluded to previously, interposed or separating the plurality of first channels and the plurality of second channels may be panels, plates, or other dividers. These dividers may separate the incoming air flow and the outgoing air flow from one another. The dividers may be made of metal (e.g., aluminum, magnesium, steel, stainless steel, etc.) or other material having a relatively high thermal conductivity. Heat may be transferred between the incoming air flow and the outgoing air flow, for instance, through the dividers interposed between the respective flows. 
     In some instances, the heat exchanger of the air handling unit may be created or formed by alternatingly stacking dividers that include the plurality of first channels and the plurality of second channels. In some instances, the plurality of first channels may be included in dividers that are disposed in a first direction while the plurality of second channels may be included in dividers that are disposed in a second direction. In some instances, a universal divider may be used to form the plurality of first channels and the plurality of second channels, but through changing an orientation of the divider (e.g., by rotating the divider 180 degrees), the dividers may couple together in an alternating, stacked relationship to form the heat exchanger. Stated another way, a first subset of the dividers may be arranged in a first direction, while a second subset of the dividers may be rotated 180 degrees be arranged in a second direction. 
     Depending on the application, the heat exchanger may have any number of alternatingly stacked plurality of first dividers and plurality of second dividers to form any number of inlets and outlets. In some instances, the number of alternatingly stacked plurality of first dividers and plurality of second dividers may be based in part on a length of the heat exchanger, dimensions of the cover, or manufacturing limitations. In other instances, the number of dividers used may depend on other size constraints and/or heat transfer requirements. Moreover, in some instances, the width of the heat exchanger, as represented by the number of alternatingly stacked plurality of first dividers and plurality of second dividers, may be a percentage or fraction of the length of the heat exchanger. For instance, the width of the heat exchanger may be between 40% and 100% of the length of the heat exchanger. In some instances, the width of the heat exchanger may limit the flow rate while the length may limit an efficiency of the heat exchanger. Having the width between 40% and 100% of the length may therefore balance flow and efficiency considerations. By way of non-limiting examples, in some instances, the heat exchanger may include between 5-10 alternatingly stacked panels, 10-20 alternatingly stacked panels, 20-30 alternatingly stacked panels, 30-40 alternatingly stacked panels, or 40-50 alternatingly stacked panels. Accordingly, a size or an amount of channels included in the heat exchanger may be increased through adding dividers of the plurality of first dividers and/or the plurality of second dividers. 
     To increase the surface area of the plurality of first channels and the plurality of second channels, the top surface and/or the bottom surface of the dividers may be wavy, bumpy, dimpled, zig-zagged, finned, or include other protrusions and/or indentations. In doing so, a rate of heat transfer, via the increased surface area, may be increased. However, when included, the protrusions and/or indentations may be selectively applied to not materially impede or adversely affect the incoming air flow and/or the outgoing air flow through the heat exchanger (i.e., turbulence). 
     In some instances, the heat exchanger may be a parallel-flow heat exchanger, a cross-flow heat exchanger, a counter-flow heat exchanger, or any combination thereof. In addition, the heat exchanger may be a shell and tube heat exchanger, a plate heat exchanger, or a plate and fin heat exchanger. 
     The heat exchanger may be configured for various air flow rates and efficiencies. For instance, the rate of incoming air flow and/or outgoing air flow may be controlled by the speed of a controller coupled to fans that draw the incoming air and the outgoing air, respectively. In some instances, the heat exchanger may be designed to operate up to or greater than 130 cubic feet per minute (cfm) and as low as 65 cfm. Depending on the flow rates or the temperature difference between the interior and exterior of the portable shelter, the heat exchanger may have efficiencies between 45% and 65%. For instance, lowering the flow rates of the incoming air flow and the outgoing air flow may increase the efficiency of the heat exchanger. However, while these ranges or values have been given, these are just examples and in other instances air handling units according to this application can be sized to handle airflows smaller or larger than this range and have efficiencies greater than those mentioned. 
     Moreover, prolonged exchange conditions between the incoming air and the outgoing air may create a heat load within the heat exchanger that degrades intake efficiency slightly and inversely increases exhaust air exchange efficiency. Such effects may be controlled or mitigated through air flow rates, a length and/or width of the dividers included in the heat exchanger, a length of the channels, or a speed of the fan(s). 
     The heat exchanger may reside within a cover of the air handling unit. In some instances, the cover may be disposed within the interior of the portable shelter to prevent increasing an exterior footprint of the portable shelter. However, in some instances, the air-handling unit may be coupled to the exterior of the portable shelter within a mechanical compartment, for instance. In some instances, the cover may be disposed on a front of the portable shelter, on either or both sides of a door that provides access to the portable shelter. However, the air handling unit may be located at other locations on the portable shelter. 
     Whether coupled to the interior, exterior, or both, portions of the air handling unit may be disposed through the wall of the portable shelter. For instance, the fans of the air handling unit may be disposed within or reside within a wall of the portable shelter. 
     The cover may include openings that permit the outgoing air to enter and exit the heat exchanger and openings through which the incoming air is permitted to enter and exit the heat exchanger. In addition, the cover may assist in routing or otherwise channeling the outgoing air towards the exterior of the portable shelter and/or routing or otherwise channeling the incoming air towards the interior of the portable shelter. 
     As mentioned above, the air handling unit may include fans that draw the incoming air and the outgoing air into and through the heat exchanger. In some instances, components of the fans, such as motors, switches, power or control units, may also be disposed within the cover. Filters may also be included within the cover or otherwise coupled to the portable shelter. As such, upon assembly, the air handling unit may resemble a sleek and compact enclosure that easily couples to the portable shelter. 
     While the heat exchanger has been described above as including alternatingly stacked dividers, other designs of heat exchangers may be included within the air handling unit. 
       FIG. 1  illustrates a partial perspective view of a portable shelter  100 . While  FIG. 1  and subsequent figures illustrate the portable shelter  100 , the portable shelter  100  is just one example of a portable shelter according to the embodiments of this application. For instance, portable shelters may include expandable shelters (e.g., shelters having one or more expandable sides) as well as non-expandable shelters. In the case of expandable shelters, the expandable portions may be hard sided (e.g., rigid walled), soft sided (e.g., flexible walled), or a combination of hard and soft sides/walls. 
     In some instances, the portable shelter  100  may have a door  102  located at a front end  104 , opposite a back end  106 , of the portable shelter  100 . The door  102  may provide access to an interior of the portable shelter  100 . 
     Disposed on either or both sides of the door  102  may be shrouds  108 . In some instances, the shrouds  108  may be coupled to an exterior surface  110  of the portable shelter  100  and may be disposed or aligned over openings in the portable shelter  100 . The shrouds  108  may include flanges, rims, brims, ports, or spouts  112 (A) and  112 (B) that project from the shrouds  108  (collectively, “the flanges  112 ”). The shrouds  108  and/or flanges  112  may have low profiles to not increase a footprint of the portable shelter  100 . 
     In some instances, the flanges  112  may be oriented in different directions. Discussed in more detail, the shrouds  108  may be arranged and configured to vent outgoing air from within the interior of the portable shelter  100  and intake incoming air that is exterior to the portable shelter  100 . 
     Sides  114 (A) and  114 (B) may extend between the front end  104  and the back end  106  of the portable shelter  100 . 
     In some instances, the portable shelter  100  may be at least partially constructed from a standard shipping container (e.g., intermodal freight container) formed of metal (e.g., steel). For instance, the portable shelter  100  may be a standard shipping container modified to include the door  102 , the sides  114 (A) and  114 (B), electrical components, plumbing, insulation, etc. In addition, given that the portable shelter  100  may be constructed from a standard shipping container, the portable shelter  100  may have dimensions similar to that of a standard shipping container. 
     In some instances, the sides  114 (A) and  114 (B) may be displaceable to expand the portable shelter  100  from a storage, stowed, shipping, retracted state or position to a deployed, use, extended state or position. During a stowed state, the sides  114 (A) and  114 (B) may include a plurality of panels that may be folded into a frame  116  of the portable shelter  100 , within the footprint of the standard shipping container, and unfolded during deployment. For instance, in some instances, the sides  114 (A) and  114 (B) may include a movable portion having an insulated ceiling panel that may fold up (e.g., with the assistance of a fluid actuated cylinder) to a position coplanar with a top of the portable shelter  100 . Two side wall panels may fold out and become coplanar or substantially coplanar with the ends (e.g., the front end  104  and the back end  106 , respectively) of the portable shelter  100 . In some instances, the two side wall panels, in the deployed state, may act as trusses to support the ceiling panel, providing structural support while enlarging the interior footprint or area of the portable shelter  100 . 
     A floor panel may be included in the sides  114 (A) and  114 (B) which folds down to a position coplanar with the bottom of the portable shelter  100 . In some instances, a winch and cable system may be employed to ease the lowering of the floor panel. A back wall panel may also be included that folds up from the floor panel, pivoting on the floor panel outer edge to which the back wall panel bottom edge is coupled. Once fully deployed, the back wall panel may provide truss support similar to that of the side wall panels discussed above. 
     By utilizing a hard-sided panel system for the sides  114 (A) and  114 (B), the portable shelter  100  may be deployed quickly and with considerable strength and insulating properties. The panels of the sides  114 (A) and  114 (B) may include structurally insulated panels (SIPs) which, in some instances, may include at least a layer of insulation material sandwiched between two thin outer skins made of structural materials. 
     Consistent with ISO and/or other standards, the portable shelter  100  may also include structural features such as slots  118  or other openings that enable the frame  116  of the portable shelter  100  to be readily transported by forklift, crane, or helicopter, for instance. 
       FIG. 2  illustrates an interior  200  of the portable shelter  100 , showing an air handling unit  202  disposed on either side of the door  102 . In  FIG. 2 , the sides  114 (A) and  114 (B) are shown as being translucent to illustrate the interior  200  of the portable shelter  100 . In conjunction with  FIG. 1 , the air handling unit  202  may be arranged and configured to receive incoming air and route the incoming air into the interior  200  of the portable shelter  100 . In addition, the air handling unit  202  may be configured to draw outgoing air and route the outgoing air towards the exterior of the portable shelter  100 . In some instances, the air handling unit  202  may draw incoming air and exhaust outgoing air through and via the shrouds  108 . 
     The air handling unit  202  may include a cover  204  that encases or surrounds parts of the air handing unit  202 . For instance, beneath the cover  204 , the air handling unit  202  may include a heat exchanger. Discussed in more detail herein, the heat exchanger may exchange heat between incoming air and outgoing air to condition the incoming air prior to reaching the interior  200  of the portable shelter  100 . To create the respective flows, fans may be included. 
     In some instances, the cover  204  may include an opening  206  that aligns or is disposed over outlets of the heat exchanger. In some instances, the opening  206  may represent an outlet where incoming air exhausts into the interior  200  of the portable shelter  100 . That is, after passing through the heat exchanger, the incoming air may exit into the interior  200  via the opening  206 . 
     The cover  204  may also include an opening  208  where outgoing air is drawn into the air handling unit  202  (pointing to an underneath side of the cover  204  of the air handling unit  202 ). After passing through the heat exchanger, the outgoing air may be exhausted exterior to the portable shelter  100 . In some instances, to allow the incoming air to circulate and disperse throughout the interior  200 , the second opening  208  may be disposed away from or located distant from the opening  206 . 
       FIG. 3  depicts the air handling unit  202  coupled to a wall  300  of the portable shelter  100 . In  FIG. 3 , the wall  300  is shown as being cross-sectioned to illustrate the disposition of the air handling unit  202  on the portable shelter  100 . In addition, a portion of the cover  204  is shown as being cross-sectioned to illustrate a heat exchanger  302  residing within the cover  204  of the air handling unit  202 . 
     The heat exchanger  302  may include a plurality of first inlets  304  disposed at or along a top of the heat exchanger  302 . In some instances, the plurality of first inlets  304  may be configured to receive incoming air. The incoming air may pass through the heat exchanger  302  and exit or be exhausted into the interior  200  of the portable shelter  100  via a plurality of first outlets  306 . The flow of the incoming air through the air handling unit  202 , and the heat exchanger  302 , may be represented by arrows  308 (A), which shows the incoming air entering the air handling unit  202 , and arrows  308 (B), which shows the incoming air exiting the air handling unit  202 . 
     The heat exchanger  302  may also include a plurality of second inlets  310  disposed at or along a bottom of the heat exchanger  302 . The plurality of second inlets  310  may be disposed away from or at an end opposite the plurality of first inlets  304 . The plurality of second inlets  310  may be configured to receive outgoing air from within the interior  200  of the portable shelter  100 . The outgoing air may pass through the heat exchanger  302  before exiting the portable shelter  100  via a plurality of second outlets  312 . The flow of the outgoing air through the air handling unit  202 , and the heat exchanger  302 , may be represented by arrows  314 (A), which shows the outgoing air entering the air handling unit  202 , and arrows  314 (B), which show the outgoing air exiting the air handling unit  202 . 
     In some instances, the plurality of first inlets  304  may be spaced away from but parallel to the plurality of second inlets  310 . Additionally, or alternatively, the plurality of first outlets  306  may be spaced away from but parallel to the plurality of second outlets  312 . Furthermore, in some instances, the plurality of first inlets  304  may be perpendicular with the plurality of first outlets  306  and/or the plurality of second inlets  310  may be perpendicular with the plurality of second outlets inlets  312 . 
     The directional flows of the incoming air and the outgoing air through the heat exchanger  302 , as indicated by arrows  308 (A),  308 (B),  314 (A), and  314 (B), may allow the incoming air to exchange heat with the outgoing air. That is, as discussed in more detail herein, extending between the plurality of first inlets  304  and the plurality of first outlets  306  may be a plurality of first channels while extending between the plurality of second inlets  310  and the plurality of second outlets  312  may be a plurality of second channels. The plurality of first channels and the plurality of second channels may be alternatingly positioned within the heat exchanger  302  such that heat may be transferred between the outgoing air and the incoming air. 
     To create the incoming air flow and the outgoing air flow, the air handling unit  202  may include fans  316 (A) and  316 (B). In some instances, the fan  316 (A) may create the incoming air flow by blowing or pushing the incoming air through the heat exchanger  302 . In some instances, the fan  316 (B) may create the outgoing air flow by drawing or pulling the incoming air through the heat exchanger  302 . The fans  316 (A) and  316 (B) may include axial fans or centrifugal fans. 
       FIG. 3  illustrates the fans  316 (A) and  316 (B) as being disposed within the wall  300  of the portable shelter  100 . However, in some instances, the fans  316 (A) and  316 (B) may be located on the exterior of the portable shelter  100  or within the interior  200  of the portable shelter  100 , such as being adjacent to the plurality of first outlets  306  and/or the plurality of second inlets  310 , respectively. In addition, filters may be included to limit or prevent dirt, dust, or other debris from entering the interior  200 . 
     The cover  204  may encapsulate or surround the heat exchanger  302 . In some instances, the cover  204  may have the opening  206  configured for the plurality of first outlets  306  and the opening  208  configured for the plurality of second inlets  310 . The opening  206  may closely abut or couple to the plurality of first outlets  306 . In some instances, to separate the plurality of first outlets  306  and the plurality of second inlets  310 , the plurality of second inlets  310  may be recessed away or disposed away from the opening  208 . As such, the incoming air may be prevented from immediately being drawn into the plurality of second inlets  310 . 
     The cover  204  may also have an opening  318  for the plurality of first inlets  304  and an opening  320  for the plurality of second outlets  312 . In some instances, the cover  204  may also have a barrier or flange  322  disposed between the opening  318  and the opening  320 . In some instances, the flange  322  may isolate the incoming air flow and the outgoing air flow. That is, to prevent the incoming air from entering the plurality of second outlets  312  and the outgoing air from entering the plurality of first inlets  304 , the flange  322  may act as a barrier to as to prevent the fan  316 (A) from blowing incoming air into the plurality of second outlets  312  while also preventing the fan  316 (B) from blowing outgoing air into the plurality of first inlets  304 . 
     At an end opposite to the plurality of second inlets  310 , the plurality of first inlets  304  may be separated from the cover  204 , creating a pocket  324  whereby the incoming air traverses or passes before entering the plurality of first inlets  304 . That is, in some instances, the fan  316 (A) may be separated from the plurality of first inlets  304 . However, in some instances, the plurality of first inlets  304  may be extended or continued towards the opening  318 . For instance, the heat exchanger  302 , by being rounded, extended, and/or directed towards the fan  316 (A), may cause the plurality of first inlets  304  to be disposed closer to or coupled to the opening  318  and/or the fan  316 (A). 
     The shrouds  108  may be disposed adjacent to the fan  316 (A) and the fan  316 (B). In some instances, the shrouds  108  may prevent the fan  316 (A) from intaking outgoing air. Stated another way, the flange  112 (B) on the shroud  108  may diffuse the outgoing air away from where the incoming air is drawn into the fan  316 (A) to reduce the fan  316 (A) from taking in outgoing air. 
       FIG. 4  illustrates a panel  400  that may be included within the heat exchanger  302 . However, while  FIG. 4  illustrates a particular layout, configuration, or shape of the panel  400 , the panel  400  may include differently shaped panels or may resemble other plates or dividers. 
     In some instances, the panel  400  may include a first end  402 , a second end  404 , a first side  406  disposed between the first end  402  and the second end  404 , as well as a second side  408  disposed between the first end  402  and the second end  404 . In addition, the panel  400  may include a top surface  410  and a bottom surface  412  (pointing to an underneath side of the panel  400 ).
         The first end  402  may include a sidewall or end wall  414  that spans a width (w) of the panel  400 . The end wall  414  may include a lip  416  that overhangs at least a portion or is disposed above the top surface  410  of the panel  400 .   The first side  406  may have a first sidewall  418  that spans a length (l) of the first side  406 . The first sidewall  418  may include a lip  420  that overhangs at least a portion or is disposed above the top surface  410  of the panel  400 .   In some instances, the second side  408  may have a second sidewall  422  that spans less than the length (l) of the panel  400 . The second sidewall  422  may include a lip  424  that overhangs at least a portion or is disposed above the top surface  410  of the panel  400 . In some instances, the lip  424  may span a length of the second sidewall  422 .       

     In combination, the sidewall  414 , the lip  416 , the sidewall  418 , the lip  420 , the sidewall  422 , and the lip  424  may create a channel  426 . In some instances, the channel  426  may be interposed between an opening  428  and an opening  430 . That is, given that no sidewall is included on the second end  404 , the opening  428  may be formed via a gap interposed between the first side  406  and the second side  408 . Similarly, as the sidewall  422  of the second side  408  may extend less than the length (l) of the panel  400 , the opening  430  may be formed via a gap interposed between the first end  402  and an end of the sidewall  422  and the flange  424 . In some instances, the opening  430  may be disposed adjacent the first end  402  of the panel  400 , such that the opening  430  may be defined in part by the sidewall  414  of the first end  402 . 
     In some instances, the opening  428  and the opening  430  may be of a similar or different size. That is, a width of the of the opening  430  may be similar, different, or equal to the width (w) of the panel. In addition, the opening  428  may be perpendicular to the opening  430 . 
     As discussed in more detail herein, the opening  428  may correspond to an inlet of the channel  426  while the opening  430  may correspond to an outlet of the channel  426 . Additionally, to create the heat exchanger  302 , a first subset or plurality of panels  400  may be orientated in a first direction, so as to create a first subset or plurality of channels in the heat exchanger  302 , while a second subset or plurality of panels  400  may be orientated in a second direction, so as to create a second subset or plurality of channels in the heat exchanger  302 . Furthermore, as the panel  400  is included within the heat exchanger  302 , to increase a surface area of the panel  400 , the top surface  410  and/or the bottom surface  412  of the panel  400  may include dimples, protrusions, indentations, or other formations. Moreover, the panel  400  may also include holes  432  used to couple multiple panels together. 
     Furthermore, the panel  400  may include more than two ends or more than two sides, with the openings disposed on any combination of the ends and the sides. In addition, the panel  400  may be rectangular-shaped, may take other shapes, or may include any combination, such as portions of the panel being circular, square, hexagonal, etc. 
       FIG. 5  illustrates a perspective view the heat exchanger  302 , showing part of the heat exchanger  302  being exploded in order to illustrate the assembly of the heat exchanger  302 . As alluded to previously in the discussion of  FIG. 4 , in some instances, the heat exchanger  302  may be formed by stacking the panel  400  amongst one another. Furthermore, the Cartesian (X-Y-Z) coordinate system included in  FIG. 5  is meant to assist in the discussion of the heat exchanger  302  and will be referenced herein. 
     The heat exchanger  302  may include a first subset or plurality of first panels  500  arranged in a first direction and a second subset or plurality of second panels  502  arranged in a second direction. In some instances, the plurality of first panels  500  and the plurality of second panels  502  may represent the panel  400 , with one of the plurality of first panels  500  or one the plurality of second panels  502  being rotated 180 degrees relative to the other. 
     To form the heat exchanger  302 , the plurality of first panels  500  and the plurality of second panels  502  may be alternatingly stacked such that panels of the plurality of first panels  500  are interposed between panels of the plurality of second panels  502 , and vice versa. In doing so, the plurality of first inlets  304 , the plurality of first outlets  306 , the plurality of second inlets  310 , and the plurality of second outlets  312  may be formed. 
     A first end  504  of the plurality of first panels  500  may include a sidewall and a second end  506  with an opening  508 . In some instances, the first end  504  may include a flange disposed over at least portion of a top surface of the plurality of first panels  500 . In addition, the plurality of first panels  500  may include a first side  510  and a second side  512 . The first side  510  and the second side  512  may include a sidewall and a flange disposed over at least a portion of the top surface of the plurality of first panels  500 . In some instances, the sidewall on the second side  512  may extend less than a length of the plurality of first panels  500  to form an opening  514 . Disposed between the opening  508  and the opening  514  may be a plurality of first channels  516 . 
     Similarly, the plurality of second panels  502  may include a first end  518  and a second end  520  with an opening  522 . In some instances, the first end  518  may include a sidewall with a flange disposed over at least portion of a top surface of the plurality of second panels  502 . In addition, the plurality of second panels  502  may include a first side  524  and a second side  526 . In some instances, the first side  524  and the second side  526  may include sidewalls and flanges, respectively, disposed over at least a portion of the top surface of the plurality of second panels  502 . The sidewall on the second side  526  may extend less than a length of the plurality of second panels  502  to form an opening  528 . Disposed between the opening  522  and the opening  528  may be a plurality of second channels  530 . 
     Moving to the formation of the heat exchanger  302 , the plurality of first panels  500  and the plurality of second panels  502  may be alternatingly rotated and stacked such that the first end  504  of the plurality of first panels  500  align or are coplanar with the second end  520  of the plurality of second panels  502 . Moreover, the first side  510  of the plurality of first panels  500  may be aligned and coplanar with the second side  526  of the plurality of second panels  502 . The first end  518  of the plurality of second panels  502  may be aligned and coplanar with the second end  506  of the plurality of first panels  500  while the first side  524  of the plurality of second panels  502  align or are coplanar with the second side  512  of the plurality of first panels  500 . 
     Through aligning the plurality of first panels  500  and the plurality of second panels  502 , as outlined above, the plurality of first panels  500  and the plurality of second panels  502  may be coupled to another to form the plurality of first inlets  304 , the plurality of first outlets  306 , the plurality of second inlets  310 , and the plurality of second outlets  312 . That is, the opening  522 , the opening  528 , the opening  508 , and the opening  514  may form the plurality of first inlets  304 , the plurality of first outlets  306 , the plurality of second inlets  310 , and the plurality of second outlets  312 , respectively. Therefore, interposed between the plurality of first inlets  304  may be the sidewall of the first end  504  of the plurality of first panels  500  while interposed between the plurality of first outlets  306  may be the sidewall of the sidewall of the first side  510  of the plurality of first panels  500 . In addition, interposed between the plurality of second inlets  310  may be the sidewall of the first end  508  while interposed between the plurality of second outlets  312  may be the sidewall of the second side  524  of the plurality of second panels  502 . 
     The sidewalls on the first end  504 , the first side  510 , and the second side  512  of the plurality of first panels  500  may serve to offset the plurality of second panels  502  to form the plurality of first channels  516 . That is, the plurality of first channels  516  may be interposed between the plurality of first panels  500  and the plurality of second panels  502 . In some instances, the plurality of first panels  500  may couple to the flanges included on the sidewalls of the first end  518 , the first side  524 , and the second side  526  of the plurality of second panels  502 . 
     The sidewalls of the first end  518 , the first side  524 , and the second side  526  of the plurality of second panels  502  may serve to offset the plurality of first panels  500  to form the plurality of second channels  530 . Accordingly, the plurality of second channels  530  may be interposed between the plurality of second panels  502  and the plurality of first panels  500 . In some instances, the plurality of second panels  502  may couple to the flanges included on the sidewalls of the first end  504 , the first side  510 , and the second side  512  of the plurality of first panels  500 . 
     On a last or final of the alternatingly stacked plurality of first panels  500  or the plurality of second panels  502  (as shown in  FIG. 5 ) may be a plate  532  that encloses a channel of either the plurality of first channels  516  or the plurality of second channels  530  (as shown in  FIG. 5 ). In some instances, the plate  532  may not include any openings and may be flat to enclose either a channel of the plurality of first channels  516  or a channel of the plurality of second channels  530 . 
     To couple the plurality of first panels  500  and the plurality of second panels  502  together, fasteners  534 (A) may be disposed through the plurality of first panels  500  and the plurality of second panels  502 . In some instances, the fastener  534 (A) may be an elongated bolt or rod disposed through respective holes in the plurality of first panels  500  and the plurality of second panels  502 , and thereafter tightened using fastener  534 (B), which may be a nut. However, the plurality of first panels  500  and the plurality of second panels  502  may be coupled together through being bonded (e.g., welding or adhesives), brazed, crimping, snap-fit, tongue and grooves, or using other mechanical fasteners, such as screws. In addition, to isolate and/or prevent intermixing of the incoming air flow and the outgoing air flow through the heat exchanger  302 , tape, caulk, or other sealants may be disposed between gaps or openings of the alternatingly stacked plurality of first panels  500  and the plurality of second panels  502 . 
     With the alternatingly stacked plurality of first panels  500  and the plurality of second panels  502 , the heat exchanger  302  may be formed such that the incoming air flow and the outgoing air flow exchange heat via the plurality of first channels  516  and the plurality second channels  530 . In some instances, the plurality of first inlets  304  may be disposed on the second end  520  of the plurality of second panels  500  (e.g., the opening  522 ) while the plurality of first outlets  306  (e.g., the opening  528 ) may be disposed on the second side  526  of the plurality of second panels  502 . The plurality of second inlets  310  may be disposed on the second end  506  of the plurality of first panels  500  (e.g., the opening  508 ) while the plurality of second outlets  312  may be disposed on the second side  512  of the plurality of first panels  500  (e.g., the opening  512 ). In doing so, the outgoing air may flow within the plurality of first channels  516  while the incoming air may flow within the plurality of second channels  530 , thereby condition the incoming air before reaching the interior  200  of the portable shelter  100 . 
     Reference is now made to the Cartesian coordinate system included in  FIG. 5 . In some instances, the plurality of first panels  500  and the plurality of second panels  502  may be stacked in the Y-direction along X-Z planes that are spaced apart in the Y-direction. In addition, one of the plurality of first panels  500  or the plurality of second panels  502  may be rotated about the Y-axis 180 degrees. With the plurality of alternatingly stacked and rotated plurality of first panels  500  and the plurality of second panels  502 , the plurality of first inlets  304  may be disposed along a first Y-Z plane spaced apart in the X direction from the plurality of second inlets  310  disposed along a second Y-Z plane. Furthermore, the plurality of first outlets  306  may be disposed along a first X-Y plane spaced apart in the Z direction from the plurality of second outlets  312  disposed along a second X-Y plane. Moreover, the plate  532  may be coupled to a last of the plurality of first panels  500  or the plurality of second panels  502  along a X-Z plane. 
     While the heat exchanger  302  is shown as having a specified number of inlets and outlets and/or using a specified number of panels, there may be any number of inlets/outlets created by the alternatingly stacked panels forming the heat exchanger  302 . That is, any number of alternatingly stacked and rotated plurality of first panels  500  and the plurality of second panels  502  may be included in the heat exchanger  302 , with a last of the alternatingly stacked plurality of first panels  500  and the plurality of second panels  502  being coupled to the second panel  532 . 
       FIGS. 6A and 6B  illustrate perspective views of the heat exchanger  302 . Compared to  FIG. 5 ,  FIGS. 6A and 6B  illustrate the heat exchanger  302  as being assembled, with the plurality of first panels  500  and the plurality of second panels  502  being in a stacked relationship. 
     Through the coupling of the plurality of first panels  500  and the plurality of second panels  502 , the plurality of first inlets  304  (along the first Y-Z plane), the plurality of first outlets  306  (along the first X-Y plane), the plurality of second inlets  310  (along the second Y-Z plane spaced apart in the X direction from the first Y-Z plane), and the plurality of second outlets  312  (along a second X-Y plane spaced apart in the Z direction from the first X-Y plane) may be formed. The plate  532  may be coupled to a last alternatingly panel of the plurality of first panels  500  and/or the plurality of second panels  502 . 
       FIG. 7  is a side view of the heat exchanger  302 , with the plate  532  enclosing a last of the plurality of first channels  516  or the plurality of second channels  530 . In addition,  FIG. 7  illustrates the fasteners  534 (B) coupling the plurality of first panels  500 , the plurality of second panels  502 , and the plate  532  together. 
       FIG. 8  illustrates an end view of the heat exchanger  302 , showing the plurality of first panels  500  and the plurality of second panels  502  being alternatingly stacked. Given that the heat exchanger  302  may be symmetrical, the end depicted in  FIG. 8  may represent the plurality of first inlets  304  or the plurality of second inlets  310 . However, in the discussion of  FIG. 8 , the plurality of second inlets  310  may be interposed between the sidewall of the first end  518  of the plurality of second panels  502 , with the plate  532  coupling to a last of the plurality of first panels  500 . 
     In addition,  FIG. 8  illustrates the fastener  534 (A) extending through the plurality of first panels  500  and the plurality of second panels  502  and fastener  534 (B) attached thereto to couple the plurality of first panels  500  and the plurality of second panels  502  together. 
       FIG. 9  illustrates the cover  204  including the opening  206  and the opening  208 . In some instances, and as mentioned previously, the cover  204  may be sized and configured to house and retain the heat exchanger  302 . That is, a depth of the cover  204  may be complimentary or corresponding to a width of the heat exchanger  302 . In addition, a depth or height of the heat exchanger  302 , as defined by an amount of the plurality of first panels  500  and the plurality of second panels  502  that are alternatingly stacked, may reside within a width of the cover  204 . Furthermore, a length of the cover  204  may be complimentary to the length of the heat exchanger  302 , such that when the heat exchanger  302  is disposed within the cover, the pocket  324  is disposed adjacent the plurality of first inlets  304 , and the plurality of second inlets  310  are recessed from the opening  208 . Accordingly, the cover  204  may have a cavity, compartment, or chamber sized to house the heat exchanger  302 . 
     A mechanical cover  900  may couple to the cover  204 , may be integrated with the cover  204 , or may be mounted proximal to where the cover  204  mounts to the portable shelter  100 . In some instances, the mechanical cover  900  may house internal components of the air handling unit  202  such as power supplies, control units, or operational equipment or cables for the fan  316 (A) and the fan  316 (B). 
     The cover  204  may include a flange  902  and the mechanical cover  900  may include a flange  904 . The flange  902  and the flange  904  may be used to couple the cover  204  and the mechanical cover  900  to the wall  300  of the portable shelter  100 , respectively. 
     The cover  204  may include a face plate  906  that couples to the cover  204  and/or the mechanical cover  900 . The face plate  906  may include an opening  908 , the opening  318 , and the opening  320 . In some instances, the opening  908  may be aligned with an opening in the mechanical cover  900  to allow components within the mechanical cover to route or traverse the opening  908 . 
     The opening  318  may provide a passageway for the incoming air to reach the plurality of first inlets  304  and pass through the heat exchanger  302 . Similarly, the opening  320  may provide a passageway for the outgoing air exiting the plurality of second outlets  312 . As mentioned in  FIG. 3 , the flange  322  may be interposed between the opening  318  and the opening  320  to prevent a mixture of the incoming air and the outgoing air. That is, the flange  322  may separate the plurality of first inlets  304  and the plurality of second outlets  312 . 
       FIGS. 10A, 10B, and 10C  illustrate various views of the heat exchanger  302  disposed within the cover  204  and the face plate  906 . However, in  FIG. 10A , the face plate  906  is shown as being disposed away from the cover  204  in order to illustrate the heat exchanger  302  disposed within the cover  204 . Once the face plate  906  is coupled to the cover  204 , the heat exchanger  302  may be interposed between the cover  204  and the face plate  906 . In addition, once coupled, the flange  322  on the face plate  906  may separate the plurality of first inlets  304  and the plurality of second outlets  312 . In some instances, the heat exchanger  302  may be coupled to portions of the cover  204  and/or the face plate  906  via fasteners, adhesives, and/or being welded, thereby securing the heat exchanger  302  within the cover  204 . 
     When the heat exchanger  302  is disposed within the cover  204  and the face plate  906  is coupled to the cover  204 , the opening  320  may be situated, aligned, disposed, or positioned over the plurality of second outlets  312 . Stated another way, the plurality of second outlets  312  may be disposed within a perimeter or outline of the opening  320 . The opening  206  may be situated, aligned, disposed, or positioned over the plurality of first outlets  306  ( FIG. 10B ), or the plurality of first outlets may be disposed within a footprint or perimeter of the opening  206 . In doing so, the incoming air may exit the opening  206  and into the interior  200  of the portable shelter  100  while the outgoing air may be exhausted out the opening  320 . 
     In some instances, the opening  206  and the opening  320  may be sized according to the plurality of first outlets  306  and the plurality of second outlets  312 , respectively. That is, the plurality of first outlets  306  and the plurality of second outlets  312  may be recessed within the opening  206  and the opening  320 , respectively, such that the incoming air is permitted to exit through the plurality of first outlets  306  via the opening  206  and outgoing air is permitted to exit the plurality of second outlets  312  via the opening  320 . 
     The plurality of first inlets  304  may be disposed away from the opening  318 . In some instances, the plurality of first inlets  304  may not abut, contact, or couple to the face plate  906  adjacent to the opening  318 . That is, the pocket  324  may be interposed between the plurality of first inlets  304  and the opening  318 . In some instances, however, the plurality of first inlets  304  may be extended or otherwise elongated such that the plurality of first inlets  304  are disposed adjacent to the opening  318  or abut the opening  318 . Therefore, in some instances, the pocket  324  may not be included within the air handling unit  202 . 
     The mechanical cover  900  may include a port  914  for receiving cables, switches, or other mechanical components for the operation of the air handling unit  202 . 
       FIG. 10C  shows the air handling unit  202 , with the plurality of second inlets  310  being situated, aligned, disposed, and/or recessed within the opening  208 , thereby receiving outgoing air. In addition,  FIG. 10C  illustrates the interplay between the plurality of first channels  516  and the plurality of second channels  530 , showing the plurality of first channels  516  being interposed between the plurality of second channels  530 , and vice versa. 
       FIG. 11  illustrates the air handling unit  202 , with the cover  204 , the mechanical cover  900 , the face plate  906 , and the fan  316 (A) and the fan  316 (B). In some instances, the fan  316 (A) and the fan  316 (B) may be disposed within an enclosure  1100 . When the air handling unit  202  is coupled to the portable shelter  100 , the enclosure  1100  may be disposed through the wall  300  of the portable shelter  100 . 
     CONCLUSION 
     While various examples and embodiments are described individually herein, the examples and embodiments may be combined, rearranged and modified to arrive at other variations within the scope of this disclosure. In addition, although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described. Rather, the specific features and acts are disclosed as illustrative forms of implementing the claims.