SOUND-REDUCING EXHAUST AIR SYSTEM

Abstract

According to various embodiments, an exhaust system includes: a housing with an air inlet that allows air to enter the housing and an air outlet that allows air to exit the housing; a vertical array of multiple fans that includes at least one upper fan and at least one lower fan, wherein the at least one upper fan is disposed above the at least one lower fan and is positioned with a horizontal offset in a horizontal direction from the at least one lower fan so that the at least one upper fan is closer to the air inlet in the horizontal direction than the at least one lower fan; and a deflector plate disposed within an inlet air plenum for the vertical array of multiple fans, wherein the deflector plate facilitates a flow of air entering the housing via the air inlet toward the at least one upper fan.

Description

BACKGROUND

Field of the Various Embodiments

The various embodiments relate generally to heating, ventilation, and air-conditioning (HVAC) technologies and, more specifically, to a sound-reducing exhaust air system.

Description of the Related Art

In industrial or commercial settings, such as warehouses, factories, and data centers, exhaust air is often removed or discarded from the facility by one or more rooftop exhaust units. In larger facilities, many such exhaust units can be required to provide sufficient exhaust capabilities. For example, these units can be positioned at various locations along the roof of a building depending upon the heating and cooling load and/or other exhaust requirements of the building.

One drawback of rooftop exhaust units, particularly when employed in large numbers, is noise generation. A typical exhaust unit includes one or more fans that discharge high volumes of air from a building, but also produce significant fan noise. Further, the elevated position of rooftop exhaust units ensures that any fan noise generated can be perceived at a greater distance, and therefore can be more impactful than fan noise generated at ground level.

Another drawback of rooftop exhaust units is power use. Energy consumption is an important concern with large commercial and industrial buildings, especially for power-intensive facilities like data centers. Oftentimes, a rooftop exhaust unit operates continuously, and consequently can consume a large quantity of power. Further, in many applications, such as a data center, a large number of rooftop exhaust units are employed for a single building. Therefore, in such applications the energy consumed by a single rooftop exhaust unit is multiplied many times.

Yet another drawback of rooftop exhaust units is water ingress. Each rooftop exhaust unit requires a roof penetration to draw exhaust air from within a building. As a result, each unit is associated with a possible route by which water can enter the building. This is particularly true for exhaust systems having an upblast configuration, in which exhaust air is discharged upward. As noted previously, in many applications a large number of rooftop exhaust units are employed for a single building. Therefore, any leak path associated with a particular model of rooftop exhaust unit is instantiated across the roof of the building. In some instances, such as in a data center application, even a single such roof leak can be catastrophic.

As the foregoing illustrates, what is needed in the art are more effective techniques for exhausting air from rooftop units.

SUMMARY

According to various embodiments, an exhaust air system includes: a housing with an air inlet that allows air to enter the housing and an air outlet that allows air to exit the housing; a vertical array of multiple fans that includes at least one upper fan and at least one lower fan, wherein the at least one upper fan is disposed above the at least one lower fan and is positioned with a horizontal offset in a horizontal direction from the at least one lower fan so that the at least one upper fan is closer to the air inlet in the horizontal direction than the at least one lower fan; and a deflector plate disposed within an inlet air plenum for the vertical array of multiple fans, wherein the deflector plate facilitates a flow of air entering the housing via the air inlet toward the at least one upper fan.

At least one technical advantage of the disclosed design relative to the prior art is that the disclosed design enables quieter operation of rooftop exhaust units for a given quantity of exhaust air flow. Another advantage of the disclosed design is that a given quantity of air can be exhausted from a building by a rooftop exhaust unit with less internal pressure drop being generated within the rooftop exhaust unit. As a result, significantly less power is consumed to exhaust the same quantity of air. A further advantage is that the potential for water ingress through a rooftop exhaust unit is greatly reduced by the elimination of a direct vertical path between an air inlet and an air outlet of the rooftop exhaust unit. These technical advantages provide one or more technological advancements over prior art approaches.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the various embodiments can be understood in detail, a more particular description of the inventive concepts, briefly summarized above, may be had by reference to various embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments of the inventive concepts and are therefore not to be considered limiting of scope in any way, and that there are other equally effective embodiments.

FIG. 1 illustrates a perspective view of an exhaust air system, according to various embodiments of the present disclosure.

FIG. 2 illustrates an exploded perspective view of the exhaust air system of FIG. 1, according to various embodiments of the present disclosure.

FIG. 3 illustrates a side cutaway view of the exhaust air system of FIG. 1, according to various embodiments of the present disclosure.

FIG. 4 illustrates a top view of the exhaust air system of FIG. 1, according to various embodiments of the present disclosure.

FIG. 5A illustrates a conceptual cross-sectional view of a turning vane, according to an embodiment of the present disclosure.

FIG. 5B illustrates a conceptual cross-sectional view of a turning vane, according to another embodiment of the present disclosure.

FIG. 6 illustrates a side cutaway view of the exhaust air system of FIG. 1 showing a curved deflector plate, according to various embodiments of the present disclosure.

Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

DETAILED DESCRIPTION

In the following description, numerous specific details are set forth to provide a more thorough understanding of the various embodiments. However, it will be apparent to one skilled in the art that the inventive concepts may be practiced without one or more of these specific details.

As noted above, issues associated with conventional rooftop exhaust units include noise generation, energy consumption, and water ingress. According to various embodiments, an exhaust system is configured to have reduced internal pressure drop and noise generation in comparison to a conventional rooftop exhaust unit. Further, the herein-described exhaust system reduces the potential for water ingress via a horizontal offset between an air inlet of the exhaust system and an upblast air outlet of the exhaust system. An embodiment of one such air-handling system is described below in conjunction with FIGS. 1-6.

FIG. 1 illustrates a perspective view of an exhaust air system 100, according to various embodiments of the present disclosure, and FIG. 2 illustrates an exploded perspective view of exhaust air system 100, according to various embodiments of the present disclosure. Exhaust air system 100 has an upblast configuration and can be implemented as a roof-mounted exhaust unit. As such, exhaust air system 100 can be coupled to or otherwise mounted on a roof curb 103 of a building, warehouse, or other structure (not shown) from which exhaust air system 100 removes air. Exhaust air system 100 draws air from an interior space of the building via an air inlet 101 and discharges the air drawn from the building via an air outlet 102. In some embodiments, air inlet 101 is coupled to ductwork for routing air from one or more interior spaces of the building to exhaust air system 100. In some embodiments, the air drawn from the building can be cooling air employed to remove heat generated within the building. In such embodiments, the cooling air is typically cooled and circulated within one or more interior spaces of the building to remove heat from various heat sources. The cooling air is then exhausted from the building via exhaust air system 100 so that additional cooling air can be circulated within the building for further cooling.

In the embodiment illustrated in FIGS. 1 and 2, exhaust air system 100 includes a bell-mouth 110 for reducing turbulence associated with air exiting exhaust air system 100 via air outlet 102. By reducing such turbulence, pressure drop (and therefore power consumption) and noise are also reduced. Additionally or alternatively, in some embodiments, a debris guard 104 is positioned in or on air outlet 102. For example, in some embodiments, debris guard 104 is disposed within bell-mouth 110, and in other embodiments, debris guard is disposed at an outlet or top edge 112 of bell-mouth 110. Debris guard 104 can prevent debris, animals, or other material from entering exhaust air system 100. Debris guard 104 can include a grate or perforated material that permits air to exit bell-mouth 110 and exhaust air system 100 with low pressure drop. Additionally or alternatively, in some embodiments, an inlet grate 106 is positioned above or on air inlet 101. In such embodiments, inlet grate 106 can be configured with sufficiently large cross members such that personnel entering exhaust air system 100 can stand on inlet grate 106 when servicing internal components of exhaust air system 100. Further, in such embodiments, inlet grate 106 can be configured with suitably sized openings between cross members so that air can pass through air inlet 101 and into exhaust air system 100 with low pressure drop.

Exhaust air system 100 can be powered by various types of power sources, such as a diesel generator and/or an electrical power source. According to various embodiments described herein, for a given quantity of exhaust air discharged via, the power consumption of exhaust air system 100 relative to a conventional exhaust system is significantly less. This is due to reduced pressure drop within exhaust air system 100 and enhanced airflow that equalizes the workload between the fans of a multiple-fan array within exhaust air system 100.

In the embodiment illustrated in FIGS. 1 and 2, exhaust air system 100 includes a housing 120 and, disposed within housing 120, a vertical fan array 130, a turning vane array 140, and a deflector plate 150. As shown, turning vane array 140 is disposed within an outlet air plenum 122 for vertical fan array 130 and deflector plate 150 is disposed within an inlet air plenum 123 for vertical fan array 130. Housing 120 includes a top wall 124, side walls 125, and a sloped floor 126. Sloped floor directs moisture entering exhaust air system 100 via air outlet 102 away from air inlet 101, thereby reducing the likelihood of water ingress via exhaust air system 100. In some embodiments, housing 120 can be configured with one or more access doors 127 positioned in side walls 125. Access doors 127 enable access to the interior of exhaust air system 100 by maintenance or repair personnel. Vertical fan array 130, turning vane array 140, and deflector plate 150 are described in greater detail below in conjunction with FIGS. 3-6.

FIG. 3 illustrates a side cutaway view of exhaust air system 100, according to various embodiments of the present disclosure, and FIG. 4 illustrates a top view of exhaust air system 100, according to various embodiments of the present disclosure. In FIG. 4, top wall 124 of housing 120 is omitted for clarity.

Outlet air plenum 122 is a region of exhaust air system 100 that is fluidly coupled to air outlet 102 and inlet air plenum 123 is a region of exhaust air system 100 that is fluidly coupled to air inlet 101. As shown, outlet air plenum 122 is disposed downstream of vertical fan array 130 and receives discharge air 302 discharged by upper fans 331 and lower fans 332 of vertical fan array 130. Conversely, inlet air plenum 123 is disposed upstream of vertical fan array 130 and receives incoming air 303 drawn into exhaust air system 100 by upper fans 331 and lower fans 332 of vertical fan array 130.

In some embodiments, outlet air plenum 122 is configured as a sound-absorbing chamber. In such embodiments, outlet air plenum 122 includes one or more sound-attenuation walls 321 that absorb or otherwise attenuate fan noise entering outlet air plenum 122 from vertical fan array 130, thereby significantly reducing fan noise exiting exhaust air system 100 via air outlet 102. In some embodiments, sound-attenuation walls 321 include the side walls 125 or portions of side walls 125 forming outlet air plenum 122. In some embodiments, sound-attenuating walls 321 include a portion 324 of top wall 124. In some embodiments, the one or more sound-attenuation walls 321 include a physical configuration for attenuating sound or a material for attenuating sound. For example, in some embodiments, the one or more sound-attenuation walls 321 include a perforated surface, sound-dampening slats, and/or an array of sound-absorbing shapes disposed on the interior surfaces of wound-attenuation walls 321, such as pyramids, projections, ridges, cavities, and/or the like. Alternatively or additionally, in such embodiments, the one or more sound-attenuation walls 321 include one or more materials for attenuating sound. Examples of such materials include foam, sponge, an acoustic surface texture, stone wool, wood fiber or wood fiber board, and cork. In some embodiments, sound-attenuation walls 321 are lined with such materials, and in other embodiments, such materials are integrated into sound-attenuation walls 321.

In the embodiment illustrated in FIGS. 3 and 4, outlet air plenum 122 includes turning vane array 140. As shown, turning vane array 140 includes a plurality of turning vanes 340 that are positioned within outlet air plenum 122 to redirect airflow from vertical fan array 130 upwards toward the bell-mouth 110 and air outlet 102 of exhaust air system 100. Thus, turning vanes 340 are for directing a flow of air generated by vertical fan array 130 from a horizontal direction 311 to a vertical direction 312. In some embodiments, turning vanes 340 are positioned to be horizontally and vertically offset from one another such that airflow is directed upwards toward air outlet 102 with little or no turbulence. As a result, a direction of flow of discharge air 302 is changed inside exhaust air system 100 without introducing significant turbulence that can cause significant pressure drop within exhaust air system 100 and additional noise perceptible outside exhaust air system 100.

In the embodiment illustrated in FIGS. 3 and 4, turning vanes 340 are implemented as curved sheet metal features installed within outlet air plenum 122. In other embodiments, turning vanes 340 can have a different configuration than that illustrated in FIG. 3. For example, in some embodiments, turning vanes 340 can have any technically feasible construction and configuration that facilitates directing the flow of air generated by vertical fan array 130 from horizontal direction 311 to vertical direction 312. Various embodiments are described below in conjunction with FIGS. 5A and 5B.

FIG. 5A illustrates a conceptual cross-sectional view of a turning vane 541, according to an embodiment of the present disclosure, and FIG. 5B illustrates a conceptual cross-sectional view of a turning vane 542, according to another embodiment of the present disclosure. As shown in FIG. 5A, turning vane 541 is formed via multiple straight or non-curved segments 501 and is not configured as a continuous smooth curve. In the embodiment illustrated in FIG. 5A, turning vane 541 is formed via five straight or non-curved segments 501. In other embodiments, turning vane 541 can include any suitable number of straight or non-curved segments 501. As shown in FIG. 5B, turning vane 542 includes a two-dimensional cross section, such as an air-foil cross-section, to further reduce turbulence induced in discharge air 302 when redirected by turning vane 542. In other embodiments, turning vane 541 can include any other two-dimensional cross section suitable for directing airflow from horizontal direction 311 to vertical direction 312.

Returning to FIGS. 3 and 4, in some embodiments, air outlet 102 is offset from air inlet 101 in a horizontal direction 313 so that no portion of air inlet vertically overlaps a portion of air outlet 102. As a result, there is no vertical leak path from air outlet 102 to air inlet 101, thereby reducing the likelihood of water ingress via exhaust air system 100.

Vertical fan array 130 is a vertical array of multiple fans that includes at least one upper fan 331 and at least one lower fan 332, where the at least one upper fan is disposed above and adjacent to the at least one lower fan 332. In the embodiment illustrated in FIGS. 3 and 4, vertical fan array 130 is implemented as a 2×2 array, and therefore includes two upper fans 331 and two lower fans 332. In other embodiments, vertical fan array includes more than or fewer than two upper fans 331 or lower fans 332. Upper fans 331 and lower fans 332 directing discharge air 302 in the same direction toward air outlet 102, for example through a backdraft damper array 338.

According to various embodiments, upper fans 331 are positioned with a horizontal offset 334 in horizontal direction 313 from lower fans 332. Thus, in such embodiments, upper fan 331 are closer to air inlet 101 in horizontal direction 313 than lower fans 332. In such embodiments, such positioning of upper fans 331 relative to lower fans 332 can equalize the workload between upper fans 331 and lower fans 332. Specifically, the presence of horizontal offset 334 between upper fans 331 and lower fans 332 increases the portion of air flowing through upper fans 331 relative to lower fans 332. As a result, for a given total flow of discharge air 302 discharged by upper fans 331 and lower fans 332, less pressure drop is generated within exhaust air system 100 during operation. By contrast, when upper fans 331 are vertically aligned with lower fans 332, upper fans 331 are “starved” of air relative to lower fans 332, and therefore cannot contribute to the flow of discharge air 302 as effectively as lower fans 332. It is noted that the magnitude of horizontal offset 334 is based on multiple factors, including the size and shape of inlet air plenum 123, the size and shape of air inlet 101, the diameter of upper fans 331 and lower fans 332, the target volume of discharge air 302 to be discharged from exhaust air system 100, the size and shape of deflector plate 150, the position of deflector plate 150 within inlet air plenum 123, and/or the like.

Deflector plate 150 is positioned within inlet air plenum 123 to modify the flow of incoming air 303 in a way that can further equalize the workload between upper fans 331 and lower fans 332. According to various embodiments, the presence of deflector plate 150 upstream of upper fans 331 and lower fans 332 increases the portion of air flowing through upper fans 331 relative to lower fans 332. Specifically, deflector plate 150 at least partially deflects incoming air 303 after entering air inlet 101 from vertical direction 312 to horizontal direction 311. As a result, for a given total flow of discharge air 302 discharged by upper fans 331 and lower fans 332, less pressure drop is generated within exhaust air system 100 during operation.

In the embodiment illustrated in FIGS. 3 and 4, deflector plate 150 is implemented as a flat plate that is disposed within inlet air plenum 123. In the embodiment, a leading edge 351 of deflector plate 150 is coupled to an edge 352 of air inlet 101 and a trailing edge 353 of deflector plate 150 is coupled to top wall 124 of inlet air plenum 123. In the embodiment illustrated in FIG. 3, deflector plate 150 prevents the flow of incoming air 303 from passing through an eddy region 255 of inlet air plenum 123. Thus, turbulence and the concomitant pressure drop within exhaust air system 100 is reduced. Generally, the size, shape, and position of deflector plate 150 can be selected based on multiple factors, including the size and shape of inlet air plenum 123, the size and shape of air inlet 101, the diameter of upper fans 331 and lower fans 332, the target volume of discharge air 302 to be discharged from exhaust air system 100, the magnitude of horizontal offset 334, and/or the like.

In the embodiment illustrated in FIGS. 3 and 4, deflector plate 150 is implemented as a flat plate. Alternatively, in some embodiments, deflector plate 150 is implemented as a curved plate disposed within inlet air plenum 123. One such embodiment is illustrated in FIG. 6.

FIG. 6 illustrates a side cutaway view of exhaust air system 100 showing a curved deflector plate 650, according to various embodiments of the present disclosure. As shown, curved deflector plate 650 is disposed within inlet air plenum 123. Further, a leading edge 651 of deflector plate 650 is coupled to edge 352 of air inlet 101 and a trailing edge 653 of deflector plate 650 is coupled to top wall 124 of inlet air plenum 123. In the embodiment illustrated in FIG. 6, deflector plate 650 prevents the flow of incoming air 303 from passing through an eddy region 655 of inlet air plenum 123. Thus, turbulence and the concomitant pressure drop within exhaust air system 100 is reduced. Similar to deflector plate 150 of FIG. 3, the size, shape, and position of deflector plate 650 can be selected based on multiple factors, including the size and shape of inlet air plenum 123, the size and shape of air inlet 101, the diameter of upper fans 331 and lower fans 332, the target volume of discharge air 302 to be discharged from exhaust air system 100, the magnitude of horizontal offset 334, and/or the like.

Returning to FIGS. 3 and 4, in operation, incoming air 303 enters air inlet 101 vertically from a roof penetration and/or a duct (not shown) through inlet grate 106, and deflector plate 150 deflects incoming air 303 toward vertical fan array 130. As described above, deflector plate 150 is positioned to reduce pressure drop across exhaust air system 100 by maintaining more even airflow across vertical fan array 130. Discharge air is 302 is discharged by upper fans 331 and lower fans 332 in horizontal direction 311, flows through turning vanes 340, and is directed into vertical direction 312 and through air outlet 102.

In an example embodiment, vertical fan array 130 is implemented as a 2×2 array and exhaust air system 100 is configured to provide a specified air flow of 68,000 SCFM at standard temperature and pressure (60° F., 50% relative humidity, 14.696 pounds per square inch, 38.5 Grains/lb dry air, and a density of 0.0761 lbs/ft3). In the example embodiments, pressure drop across exhaust air system 100 can be reduced to approximately 0.4 inches water gage (external static pressure) to improve power consumption and reduce the horsepower requirements of motors powering the unit.

In sum, the various embodiments shown and provided herein set forth an exhaust air system with a vertical fan array that enables quieter operation and generates less pressure drop than conventional exhaust air systems. The exhaust system includes a deflector plate disposed in an air inlet plenum that deflects incoming air toward upper fans in the vertical fan array. In addition, the upper fans of the vertical fan array are horizontally offset from the lower fans of the vertical fan array to further increase the portion of air flowing through the upper fans relative to the lower fans. The exhaust system further includes a turning vane array disposed in an air outlet plenum that directs discharge air from a horizontal direction to a vertical direction.

At least one technical advantage of the disclosed design relative to the prior art is that the disclosed design enables quieter operation of rooftop exhaust units for a given quantity of exhaust air flow. Another advantage of the disclosed design is that a given quantity of air can be exhausted from a building by a rooftop exhaust unit with less internal pressure drop being generated within the rooftop exhaust unit. As a result, significantly less power is consumed to exhaust the same quantity of air. A further advantage is that the potential for water ingress through a rooftop exhaust unit is greatly reduced by the elimination of a direct vertical path between an air inlet and an air outlet of the rooftop exhaust unit. These technical advantages provide one or more technological advancements over prior art approaches.

Any and all combinations of any of the claim elements recited in any of the claims and/or any elements described in this application, in any fashion, fall within the contemplated scope of the present invention and protection.

The descriptions of the various embodiments have been presented for purposes of illustration, but are not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.

While the preceding is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. An exhaust air system, comprising: a housing with an air inlet that allows air to enter the housing and an air outlet that allows air to exit the housing;a vertical array of multiple fans that includes at least one upper fan and at least one lower fan, wherein the at least one upper fan is disposed above the at least one lower fan and is positioned with a horizontal offset in a horizontal direction from the at least one lower fan so that the at least one upper fan is closer to the air inlet in the horizontal direction than the at least one lower fan; anda deflector plate disposed within an inlet air plenum for the vertical array of multiple fans, wherein the deflector plate facilitates a flow of air entering the housing via the air inlet toward the at least one upper fan.

2. The exhaust air system of claim 1, wherein the deflector plate prevents the flow of air entering the housing from passing through an eddy region of the inlet air plenum.

3. The exhaust air system of claim 1, wherein the deflector plate comprises a flat plate that is disposed within the inlet air plenum.

4. The exhaust air system of claim 1, wherein a leading edge of the deflector plate is coupled to an edge of the air inlet.

5. The exhaust air system of claim 1, wherein a trailing edge of the deflector plate is coupled to a top wall of the inlet air plenum.

6. The exhaust air system of claim 1, wherein the deflector plate comprises a curved plate that is disposed within the inlet air plenum.

7. The exhaust air system of claim 1, wherein the shape of the deflector plate is based at least in part on the horizontal offset.

8. The exhaust air system of claim 1, wherein the at least one upper fan includes a first fan for directing a first portion of air entering the housing toward the air outlet and a second fan for directing a second portion of air entering the housing toward the air outlet.

9. The exhaust air system of claim 8, wherein the first fan and the second fan are adjacent to each other.

10. The exhaust air system of claim 1, wherein the at least one lower fan includes a first fan for directing a first portion of air entering the housing toward the air outlet and a second fan for directing a second portion of air entering the housing toward the air outlet.

11. The exhaust air system of claim 10, wherein the first fan and the second fan are adjacent to each other.

12. The exhaust air system of claim 1, further comprising an array of turning vanes disposed within an outlet air plenum for the vertical array of multiple fans, wherein the array of turning vanes are for directing a flow of air generated by the vertical array of multiple fans from the horizontal direction to a vertical direction.

13. The exhaust air system of claim 12, wherein the outlet air plenum comprises a sound-absorbing chamber.

14. The exhaust air system of claim 1, further comprising a sound-absorbing chamber with one or more sound-attenuation walls.

15. The exhaust air system of claim 14, wherein the one or more sound-attenuation walls include at least one of a physical configuration for attenuating sound or a material for attenuating sound.

16. The exhaust air system of claim 15, wherein the physical configuration for attenuating sound comprises at least one of a perforated surface, sound-dampening slats, or an array of sound-absorbing shapes.

17. The exhaust air system of claim 15, wherein the material for attenuating sound comprises at least one of foam, sponge, an acoustic surface texture, stone wool, wood fiber (board), or cork.

18. The exhaust air system of claim 1, wherein the air inlet is offset from the air outlet in the horizontal direction so that no portion of the air inlet vertically overlaps a portion of the air outlet.

19. An exhaust air system, comprising: a housing with an air inlet that allows air to enter the housing and an air outlet that allows air to exit the housing;a vertical array of multiple fans that includes at least one upper fan and at least one lower fan, wherein the at least one upper fan is disposed above the at least one lower fan and is positioned with a horizontal offset in a horizontal direction from the at least one lower fan so that the at least one upper fan is closer to the air inlet in the horizontal direction than the at least one lower fan; andan array of turning vanes disposed within an outlet air plenum for the vertical array of multiple fans, wherein the array of turning vanes are for directing a flow of air generated by the vertical array of multiple fans from the horizontal direction to a vertical direction.

20. The exhaust air system of claim 19, wherein the outlet air plenum comprises a sound-absorbing chamber.