ROOF-MOUNTED EXHAUST UNIT

Abstract

A roof-mounted exhaust unit including an inlet portion configured to receive exhaust air; an outlet portion through which the exhaust air exits the roof-mounted exhaust unit; a plurality of exhaust fans positioned downstream from the inlet and upstream from the outlet; a plurality of gravity dampers respectively associated with the exhaust fans, the gravity dampers positioned downstream from the exhaust fans and being configured to open when the exhaust air impacts the gravity dampers at a threshold velocity; and at least one acoustic absorbing panel configured to absorb sound produced by the roof-mounted exhaust unit.

Description

BACKGROUND

Field of the Various Embodiments

Embodiments of the present disclosure relate generally to roof-mounted exhaust systems.

Description of the Related Art

For many large facilities, the ability to remove large volumes of air is critical to their operation. For example, in data center environments, large volumes of air are required to properly cool equipment installed within the environment because of the amount of heat that can be generated within the data center. In many cases, the removal or venting of air can be achieved by exhausting the air through the roof of the building utilizing traditional exhaust fans. However, traditional exhaust systems can require a significant amount of power and produce a significant amount of noise pollution. Exhaust fans can be located and spaced throughout the roof space depending on the specific heating loads of the facility. In a data center application, the facility can have different heating and exhaust air requirements dependent on the data center's heat loads and outdoor weather conditions. Accordingly, there can be significant demands placed on the roof-mounted exhaust units which in turn can also have significant power consumption and sound power levels associated with their operation.

In light of the above, more effective techniques for venting air from facilities to meet ventilation requirements are desired.

SUMMARY

The various embodiments set forth a system for a roof-mounted exhaust system. The system includes an inlet portion configured to receive exhaust air, an outlet portion through which the exhaust air exits the roof-mounted exhaust unit, a plurality of exhaust fans positioned downstream from the inlet and upstream from the outlet, a plurality of gravity dampers respectively associated with the exhaust fans, the gravity dampers positioned downstream from the exhaust fans and being configured to open when the exhaust air impacts the gravity dampers at a threshold velocity, at least one acoustic absorbing panel configured to absorb sound produced by the roof-mounted exhaust unit

At least one advantage of the disclosed embodiments is that air can be vented from an interior space using a system that consumes less power and/or produces less noise than prior art embodiments.

BRIEF DESCRIPTION OF THE DRAWINGS

So that the manner in which the above recited features of the one or more embodiments can be understood in detail, a more particular description of the one or more embodiments, briefly summarized above, may be had by reference to certain specific embodiments, some of which are illustrated in the appended drawings. It is to be noted, however, that the appended drawings illustrate only typical embodiments and are therefore not to be considered limiting of its scope in any manner, for the scope of the various embodiments subsumes other embodiments as well.

FIG. 1 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 2 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 3 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 4 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 5 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 6 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 7 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 8 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

FIG. 9 is a perspective view of a roof-mounted exhaust unit according to one or more embodiments of the present disclosure.

For clarity, identical reference numbers have been used, where applicable, to designate identical elements that are common between figures. It is contemplated that features of one embodiment may be incorporated in other embodiments without further recitation.

DETAILED DESCRIPTION

Disclosed herein is an acoustic discharge fan array unit that can act as a roof-mounted exhaust unit. Examples of the disclosure can exhaust air from an interior space without producing the excess noise levels that are associated with other designs. In various types of building environments, particularly in large scale commercial or industrial buildings, one or more roof-mounted exhaust units are utilized to remove or discard air from the indoor environment and discharge the air to the exterior of the building. In certain environments that can have intense cooling demands, such as data center environments, multiple roof-mounted exhaust units are often utilized to meet the air management or ventilation needs of the interior space. For example, a data center environment can be filled with numerous racks of servers and computing devices that are running around the clock. The devices located within the data center environment can generate intense amounts of heat relative to typical interior spaces. As the computing needs of users continues to increase with the rise of artificial intelligent, network computing, cryptocurrencies, and future-arising technologies, data centers might be desired to be placed near residential areas or areas in which noise regulations are enforced.

In some scenarios, a data center environment can require many times more cooling capacity than a typical office setting. As a result, such an environment can require many times more exhaust units to discard air from the interior environment. As the number of exhaust units increases, so do the power consumption and noise pollution produced by the data center. For example, a roof-mounted exhaust unit can include multiple fans that can run potentially constantly depending upon the cooling or heating needs of the interior space. The fans can produce significant environmental effects, such as noise pollution and energy consumption. In the case of a data center environment, noise pollution can be a factor that limits where the data center can be located. In some scenarios, placing a data center close to urban environments can be desirable from an operational point of view. However, if the environmental effects of the data center are not minimized, regulatory concerns can prevent such placement of the data center.

Accordingly, examples of the present disclosure are directed to a design of a roof-mounted exhaust unit that has sound reducing properties to reduce the noise pollution produced by the unit and, in some instances, can consume less power than traditional designs.

A roof-mounted exhaust unit 100 according to examples of the disclosure can comprise three modular sections. Each section can be independently manufactured and assembled on-site or near time of delivery of the roof-mounted exhaust unit 100 to a structure on which the roof-mounted exhaust unit 100 is installed. The roof-mounted exhaust unit 100 can be assembled from the three modular sections to provide for production schedule and resource allocation flexibility.

First, a transition section can couple the roof-mounted exhaust unit 100 to the roof of a building on which the roof-mounted exhaust unit 100 is installed. The transition section can connect the roof-mounted exhaust unit 100 to one or more apertures on the roof of a building through which air can be vented from the interior of the building and through the roof-mounted exhaust unit 100. Moving away from the roof of the building, or downstream from an inlet 101, the transition section 103 can be connected to one or more fan boxes 104, which can operate to draw air from the interior space of the building and through the roof-mounted exhaust unit 100. Moving further away from the building, the one or more fan boxes 104 can then be coupled to a discharge section, or an outlet 102. Air drawn through the roof-mounted exhaust unit 100 by the fan boxes can exit the roof-mounted exhaust unit 100 through the discharge section. In some examples, as described below and depicted in the accompanying drawings, one or more sections of the roof-mounted exhaust unit 100 can be provided with acoustic features that can reduce the sound produced by the roof-mounted exhaust unit 100.

FIG. 1 illustrates a perspective view of the roof-mounted exhaust unit 100 according to examples of the disclosure. In the subsequent figures, views and cutaway views can illustrate the design features of the roof-mounted exhaust unit 100. In operation, the roof-mounted exhaust unit 100 can be mounted on the roof of a facility to exhaust air that needs to be discarded from the interior space. Exhaust air can be air that has been cooled and circulated within the interior space and that now requires removal from the interior space so that additional cooled air can be circulated into the building to maintain the temperature of the interior space within acceptable levels. The roof-mounted exhaust unit 100 can be mounted atop an exhaust vent or an aperture on or near the roof of a building such that air enters the roof-mounted exhaust unit 100 at inlet 101, or an inlet portion.

Air can exit the roof-mounted exhaust unit 100 at outlet 102, or an outlet portion. The outlet 102 may comprise one or more outlet portions that respectively correspond to a fan box from the one or more fan boxes 104. In the depicted example, outlet 102 comprises four outlet portions that each correspond to respective fans from the one or more fan boxes 104 of the roof-mounted exhaust unit 100. The one or more fan boxes 104 of the roof-mounted exhaust unit 100 is shown in the subsequent drawings. Outlet 102 may be lined with or constructed from acoustic absorbing panels 105. The acoustic absorbing panels 105 can be designed to reduce noise generated by the fan operation and noise caused by airflow through the mechanical components. The acoustic absorbing panels 105 can be constructed from foam, fabrics, wood, or other natural or synthetic sound deadening or sound absorbing materials. By lining the outlet 102 with acoustic absorbing panels 105, the sound levels emitted by the roof-mounted exhaust unit 100 into the exterior environment can be reduced. The acoustic absorbing panels 105 can surround an interior of the outlet 102 of the roof-mounted exhaust unit 100.

FIG. 1 also depicts the transition section 103. The inlet 101 of the transition section 103 is sized specifically to match existing curbs already installed on data centers. This sizing allows the exhaust unit to be used in retrofit situations where a quieter and more power efficient exhaust unit is required or desired without the need to alter curbs or roof penetrations. The inlet 101 can have a cross-sectional area that is smaller than a cross-sectional area of the outlet 102. The transition section 103 can adapt the smaller cross-sectional area of the inlet 101 to the larger cross-sectional area of the outlet 102.

The roof-mounted exhaust unit 100 is equipped with a personnel access panel 106 in the transition section 103. The personnel access panel 106 is provided so that maintenance or repair personnel can access the interior of the roof-mounted exhaust unit 100 to gain access to an interior of the roof-mounted exhaust unit 100. However, once the roof-mounted exhaust unit 100 is installed, access to this area of the exhaust unit can be restricted or sealed for safety purposes. In some implementations, access to the roof-mounted exhaust unit 100, once installed, can be restricted to a walkable floor section that can be installed above the roof curb.

The roof-mounted exhaust unit 100 may also be configured with one or more bolted access panels 107, which can be used to access respective fans from the one or more fan boxes 104 that are internal to the roof-mounted exhaust unit 100. The bolted access panels 107 allows access to each of the one or more fan boxes 104 while still allowing the roof-mounted exhaust unit 100 to remain functional with the remaining fans that are not being accessed.

Referring next to FIG. 2, shown is an exploded perspective view of the roof-mounted exhaust unit 100 according to various examples of the disclosure. In the exploded perspective view of FIG. 2, certain interior components are shown. Others that are not shown in the exploded perspective view are discussed with reference FIGS. 3-5.

The roof-mounted exhaust unit 100 can include one or more exhaust fans 216. The one or more exhaust fans 216 can be installed within the one or more fan boxes 104. The one or more exhaust fans 216 can be arranged in a two-by-two array of fans that are powered and are configured to draw airflow into the roof-mounted exhaust unit 100 from the inlet 101. A flow straightener 217 that can be semispherical in shape can also be installed at a respective inlet of each individual fan of the one or more exhaust fans 216. In one example, the flow straightener 217 can comprise a honeycomb air straightener or a screened semispherical air straightener. A flow straightener 217 can be respectively sized for each of the one or more exhaust fans 216. The flow straighteners 217 can facilitate a more laminar airflow through each of the fans, which in turn can allow a fan to run more efficiently than if the flow straightener 217 is not utilized. By allowing the fan to run more efficiently, the fan can consume less power and generate less noise.

Referring to FIG. 3, shown is a side exploded view of the roof-mounted exhaust unit 100 that illustrates the flow straighteners 217 relative to the one or more exhaust fans 216a, 216b, 216c, and 216d. The flow straighteners 217 can be installed after the inlet 101 but before the one or more exhaust fans 216 to reduce turbulence of airflow exiting the building and flowing through each of the one or more exhaust fans 216. By reducing turbulence of airflow exiting the building onto which the, again, the one or more exhaust fans 216 can be operated more efficiently, and therefore with less power consumption and less generated noise.

The array configuration of the one or more exhaust fans 216 is shown in more detail in the subsequent drawings.

Returning to FIG. 2, as air is drawn through the one or more exhaust fans 216, airflow can discharge through a gravity damper 215 respectively installed above each fan. In other words, the gravity dampers 215 can be installed downstream of the fan array. Each gravity damper 215 can include two independently hinged or independently operated doors. Each gravity damper 215 can be configured to open when the one or more exhaust fans 216 are activated to draw air through the roof-mounted exhaust unit 100. The force of air being drawn through the roof-mounted exhaust unit 100 can open each gravity damper 215. When the one or more exhaust fans 216 are not operating, the gravity dampers 215 can close due to gravity.

In one example, one of the doors of each gravity damper 215 can be weighted such that one of the doors is heavier than the other. Referring to FIG. 4, shown is an example of a gravity damper 215 that is weighted using a weight 401. In this way, one of the doors is heavier than the other. By weighting one of the damper doors of the gravity damper 215, the unweighted or lighter door can open first as one of the one or more exhaust fans 216 is activated and as fan speed is increased. Until the fan speed reaches a velocity threshold such that air impacts the damper door at the threshold velocity, the damper door to which the weight 401 is applied remains closed. By weighting one of the damper doors, the air velocity passing through the gravity damper 215 is focused through the unweighted or lighter door opening until the air velocity reaches a threshold that overcomes the weight of the weight 401 and the damper door.

In other words, one of the doors of the gravity damper 215 can open at a first air velocity that is lower than a second air velocity at which the other door opens.

The doors of the gravity damper 215 can be positioned adjacent to one another and both can be hinged along a center axis of a respective gravity damper 215 so that airflow through the gravity damper 215 is directed in opposing directions.

By weighting one of the doors of the gravity damper 215 so that only one of the doors opens at air velocities below a threshold the single door opening prevents or reduces water intrusion into the roof-mounted exhaust unit 100 when the one or more exhaust fans 216 are operating at less than maximum revolutions per minute (RPM). Once the one or more exhaust fans 216 reach a maximum operating parameter, both damper doors of the gravity damper 215 can open to a maximum allowable angle. In one implementation, the maximum operating parameter of the one or more exhaust fans 216 can be approximately 1014 RPM. When the one or more exhaust fans 216 are operating at or near a maximum operating parameter, airflow exiting the roof-mounted exhaust unit 100 can prevent water intrusion into the interior of the unit.

Referring next to FIG. 5, shown is a cross-sectional view of a portion of the roof-mounted exhaust unit 100. The cross-sectional view shows a portion of the one or more exhaust fans 216, the gravity damper 215, acoustic absorbing panels 105, and the outlet 102 of the roof-mounted exhaust unit 100. As shown in FIG. 5, in one implementation, a maximum angle at which the doors of the gravity damper 215 open may be configured at approximately 62 degrees relative to a horizontal plane of the roof-mounted exhaust unit 100.

Regardless of the maximum angle that is selected, by limiting opening of the doors of the gravity damper 215 to a maximum angle, discharge airflow from the one or more exhaust fans 216 and out of the roof-mounted exhaust unit 100 through the outlet 102 is forced into a more laminar pattern across the face of the outlet 102 from the one or more exhaust fans 216 compared to an implementation that does not limit the opening to a maximum angle. Additionally, by limiting the doors of the gravity damper 215 to a maximum angle opening, dead spots in airflow exiting the gravity damper 215 can be limited, which can allow precipitation to enter the interior of one or more exhaust fans 216. A dead spot in this sense can comprise a spot in the opening of the gravity damper 215 that lacks enough airflow to prevent precipitation from entering the roof-mounted exhaust unit 100 during rainfall or other weather conditions involving precipitation.

Also shown in FIG. 5 are relief slots 511 that are incorporated into a frame of the gravity damper 215. The relief slots 511 provide some measure of airflow from the one or more fan boxes 104 to the exterior of the roof-mounted exhaust unit 100 so that when the one or more exhaust fans 216 are operating at significantly reduced RPM such that the doors of the gravity damper 215 are not forced open, air exiting the roof-mounted exhaust unit 100 can bypass the gravity damper 215 and exit the roof-mounted exhaust unit 100 through the relief slots 511. In other words, the relief slots 511 provide an airflow pathway external to the roof-mounted exhaust unit 100 when the gravity dampers 215 are in a closed position.

Referring next to FIG. 6, shown is an alternative cross-sectional view of the roof-mounted exhaust unit 100 according to examples of the disclosure. In the example shown in FIG. 6, the exhaust fan housings are configured to prevent or reduce water penetration into the roof-mounted exhaust unit 100 from the outside environment. In the example shown in FIG. 6, a top panel 631 of a housing of the one or more exhaust fans 216 can be sloped or inclined toward an outside or outer edge of the roof-mounted exhaust unit 100. In one example, the slope can be an approximate 2.5 degree slope.

In one example, the outer edge of the roof-mounted exhaust unit 100 can be equipped with drainage slots 613 that allow for moisture to drain from the top panel 631 to the drainage slots 613. The drainage slots 613 are configured such that water or other liquids that are not expelled by operation of the one or more exhaust fans 216 and that comes to rest on the top panel 631 can run off the side of the roof-mounted exhaust unit 100. The slope of the top panel 631 can also facilitate the flow or moisture to the drainage slots 613.

Referring next to FIG. 7, shown is a top plan view of the roof-mounted exhaust unit 100. In the top plan view, the top panels 631a, 631b, 631c, and 631d of the respective one or more exhaust fans 216 are shown. The top panels 631 are sloped toward the outside edge of the roof-mounted exhaust unit 100 and toward the drainage slots 613 that are positioned along the outside edge of the roof-mounted exhaust unit 100. In the top plan view, a stopper 701 is shown integrated into the gravity damper 215. The stopper 701 can be configured to prevent the gravity damper 215 from opening at more than the maximum allowable angle when the one or more exhaust fans 216 are activated. In some implementations, more than one stopper 701 can be utilized per gravity damper 215 to provide additional stability in stopping the gravity damper 215 from opening at more than the maximum allowable angle.

Also in the example of FIG. 7, the one or more exhaust fans 216 configured in a two-by-two fan array are shown. Other fan array configurations can be utilized in examples of the roof-mounted exhaust unit 100. For example, a 3x2, 3x3, 4x4, or any other configuration of a fan array can be utilized depending upon the building requirements in which the roof-mounted exhaust unit 100 is utilized. Additionally, the gravity dampers 215 can be offset in an alternating fashion by 90 degrees with respect to one another.

Referring next to FIG. 8, a partial perspective view of the roof-mounted exhaust unit 100 is shown. In the example of FIG. 8, center dividers 763 are illustrated. The center dividers 763 can be positioned in the outlet 102 and separate the one or more exhaust fans 216 from one another. The center dividers 763 can extend downwards to the one or more exhaust fans 216 so as to not allow any discharge air to force water into the relief slots 511 on an adjacent fan 216. Additionally, the center dividers 763 can be lined with or constructed from acoustic absorbing panels 105.

The roof-mounted exhaust unit 100 can be powered by various types of power sources, such a diesel generator or an electrical power source. Additionally, because of the design features of the roof-mounted exhaust unit 100, the roof-mounted exhaust unit 100 results in a horsepower draw or power consumption metric that is lower relative to prior art designs.

Referring next to FIG. 9, shown is a perspective view of the roof-mounted exhaust unit 100. Fans from the one or more fan boxes 104 may be installed on slide rails 218 lined with ultra-high molecular weight polyethylene (UHMW) or any other lubricating material to allow the fan to be removed without the need for external mechanical assistance. The UHMW also ensures that there is minimal steel-to-steel contact that may cause corrosion and prevent the fan from being removed. Accordingly, by removing a respective one or more bolted access panels 107 corresponding to one of the one or more exhaust fans 216, an exhaust fan 216 can be removed for servicing or replacement without removing or replacing the roof-mounted exhaust unit 100.

Examples of the disclosure can operate to reduce overall sound pressure levels of air leaving the outlet 102. Additionally, pressure drop across the roof-mounted exhaust unit 100 can be minimized to approximately 0.4 inches water gage (external static pressure) across the unit to optimize power consumption and reduce the horsepower requirements of motors powering the unit. The roof-mounted exhaust unit 100 can also provide a specified air flow of approximately 68,000 SCFM at STP (60 deg F., 50% RH, 14.696 PSI (A), 38.5 Grains/lb dry air, and a density of 0.0761 lbs/ft3.

The use of terminology such as upstream and downstream are meant to reflect the position of elements relative to each other with respect to how airflow passes through the roof-mounted exhaust unit 100. For example, a first element that is upstream from a second element is positioned closer to the source of air entering the roof-mounted exhaust unit 100, which is often but not necessarily closer to the roof of a building on which the roof-mounted exhaust unit 100 is installed. The second element is downstream from the first element in that air entering the roof-mounted exhaust unit 100 encounters the second element after the first element. In most cases, the second element is farther away from the roof and closer to the outlet 102 or the roof-mounted exhaust unit 100.

A phrase, such as “at least one of X, Y, or Z,” unless specifically stated otherwise, is to be understood with the context as used in general to present that an item, term, etc., can be either X, Y, or Z, or any combination thereof (e.g., X, Y, and/or Z). Similarly, “at least one of X, Y, and Z,” unless specifically stated otherwise, is to be understood to present that an item, term, etc., can be either X, Y, and Z, or any combination thereof (e.g., X, Y, and/or Z). Thus, as used herein, such phrases are not generally intended to, and should not, imply that certain embodiments require at least one of either X, Y, or Z to be present, but not, for example, one X and one Y. Further, such phrases should not imply that certain embodiments require each of at least one of X, at least one of Y, and at least one of Z to be present.

Although embodiments have been described herein in detail, the descriptions are by way of example. The features of the embodiments described herein are representative and, in alternative embodiments, certain features and elements may be added or omitted. Additionally, modifications to aspects of the embodiments described herein may be made by those skilled in the art without departing from the spirit and scope of the present disclosure defined in the following claims, the scope of which are to be accorded the broadest interpretation so as to encompass modifications and equivalent structures.

1. A roof-mounted exhaust unit, comprising: an inlet portion configured to receive exhaust air; an outlet portion through which the exhaust air exits the roof-mounted exhaust unit; a plurality of exhaust fans positioned downstream from the inlet and upstream from the outlet; a plurality of gravity dampers respectively associated with the exhaust fans, the gravity dampers positioned downstream from the exhaust fans and being configured to open when the exhaust air impacts the gravity dampers at a threshold velocity; and at least one acoustic absorbing panel configured to absorb sound produced by the roof-mounted exhaust unit.

2. The roof-mounted exhaust unit of clause 1, wherein the plurality of exhaust fans comprise a two-by-two array of exhaust fans, wherein each of the exhaust fans is coupled to a respective gravity damper from the plurality of gravity dampers.

3. The roof-mounted exhaust unit of any of clauses 1 to 2, wherein each of the gravity dampers comprises a first door and a second door, wherein the first door is adjacent to the second door and the first door and second door are hinged along a center axis of an opening of a respective gravity damper.

4. The roof-mounted exhaust unit of any of clauses 1 to 3, wherein each of the gravity dampers further comprises at least one stopper that limits an opening of the first door and the second door to a maximum allowable angle.

5. The roof-mounted exhaust unit of any of clauses 1 to 4, wherein the maximum allowable angle is 62 degrees.

6. The roof-mounted exhaust unit of any of clauses 1 to 5, wherein the first door is lighter than the second door so that the first door opens when the exhaust air impacts the first door at a first velocity but the second door does not open when the exhaust air impacts the first door at the first velocity.

7. The roof-mounted exhaust unit of any of clauses 1 to 6, the exhaust fans are separated from each other by at least one divider panel, the at least one divider panel comprising an acoustic absorbing panel.

8. The roof-mounted exhaust unit of any of clauses 1 to 7, wherein each of the plurality of exhaust fans comprises a top panel positioned downstream from the plurality of fans, wherein the top panel is configured with an incline towards an outer edge of the roof-mounted exhaust unit.

9. The roof-mounted exhaust unit of any of clauses 1 to 8, wherein the top panel comprises a plurality of relief slots, the plurality of relief slots providing an airflow pathway external to the roof-mounted exhaust unit when the gravity dampers are in a closed position.

10. The roof-mounted exhaust unit of any of clauses 1 to 9, wherein an outer edge of the roof-mounted exhaust unit comprises at least one drainage slot positioned downstream from the plurality of exhaust fans, the at least drainage slot configured to drain liquids from the outlet portion.

11. The roof-mounted exhaust unit of any of clauses 1 to 10, further comprising a plurality of flow straighteners upstream from the plurality of exhaust fans, wherein each of the flow straighteners respectively corresponds to one of the plurality of exhaust fans.

12. The roof-mounted exhaust unit of any of clauses 1 to 11, further comprising a plurality of acoustic absorbing panels surrounding the outlet portion, wherein the plurality of acoustic absorbing panels are downstream from the exhaust fans.

13. The roof-mounted exhaust unit of any of clauses 1 to 12, further comprising each of the plurality of exhaust fans is associated with an access panel, wherein a respective exhaust fan is removable upon removal of the access panel.

14. The roof-mounted exhaust unit of any of clauses 1 to 13, each of the plurality of exhaust fans is installed on a lubricated rail and each of the plurality of exhaust fans is removal via the lubricated rail.

15. The roof-mounted exhaust unit of any of clauses 1 to 14, wherein the inlet portion comprises a first cross section and the outlet portion comprises a second cross section, wherein the first cross section is smaller than the second cross section.

16. The roof-mounted exhaust unit of any of clauses 1 to 15, further comprising a transition section, the transition section adapting the first cross section of the inlet portion to the second cross section of the outlet portion.

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. A roof-mounted exhaust unit, comprising: an inlet portion configured to receive exhaust air;an outlet portion through which the exhaust air exits the roof-mounted exhaust unit;a plurality of exhaust fans positioned downstream from the inlet and upstream from the outlet;a plurality of gravity dampers respectively associated with the exhaust fans, the gravity dampers positioned downstream from the exhaust fans and being configured to open when the exhaust air impacts the gravity dampers at a threshold velocity; andat least one acoustic absorbing panel configured to absorb sound produced by the roof-mounted exhaust unit.

2. The roof-mounted exhaust unit of claim 1, wherein the plurality of exhaust fans comprise a two-by-two array of exhaust fans, wherein each of the exhaust fans is coupled to a respective gravity damper from the plurality of gravity dampers.

3. The roof-mounted exhaust unit of claim 1, wherein each of the gravity dampers comprises a first door and a second door, wherein the first door is adjacent to the second door and the first door and second door are hinged along a center axis of an opening of a respective gravity damper.

4. The roof-mounted exhaust unit of claim 3, wherein each of the gravity dampers further comprises at least one stopper that limits an opening of the first door and the second door to a maximum allowable angle.

5. The roof-mounted exhaust unit of claim 4, wherein the maximum allowable angle is 62 degrees.

6. The roof-mounted exhaust unit of claim 3, wherein the first door is lighter than the second door so that the first door opens when the exhaust air impacts the first door at a first velocity but the second door does not open when the exhaust air impacts the first door at the first velocity.

7. The roof-mounted exhaust unit of claim 1, the exhaust fans are separated from each other by at least one divider panel, the at least one divider panel comprising an acoustic absorbing panel.

8. The roof-mounted exhaust unit of claim 1, wherein each of the plurality of exhaust fans comprises a top panel positioned downstream from the plurality of fans, wherein the top panel is configured with an incline towards an outer edge of the roof-mounted exhaust unit.

9. The roof-mounted exhaust unit of claim 8, wherein the top panel comprises a plurality of relief slots, the plurality of relief slots providing an airflow pathway external to the roof-mounted exhaust unit when the gravity dampers are in a closed position.

10. The roof-mounted exhaust unit of claim 1, wherein an outer edge of the roof-mounted exhaust unit comprises at least one drainage slot positioned downstream from the plurality of exhaust fans, the at least drainage slot configured to drain liquids from the outlet portion.

11. The roof-mounted exhaust unit of claim 1, further comprising a plurality of flow straighteners upstream from the plurality of exhaust fans, wherein each of the flow straighteners respectively corresponds to one of the plurality of exhaust fans.

12. The roof-mounted exhaust unit of claim 1, further comprising a plurality of acoustic absorbing panels surrounding the outlet portion, wherein the plurality of acoustic absorbing panels are downstream from the exhaust fans.

13. The roof-mounted exhaust unit of claim 1, further comprising each of the plurality of exhaust fans is associated with an access panel, wherein a respective exhaust fan is removable upon removal of the access panel.

14. The roof-mounted exhaust unit of claim 1, each of the plurality of exhaust fans is installed on a lubricated rail and each of the plurality of exhaust fans is removal via the lubricated rail.

15. The roof-mounted exhaust unit of claim 1, wherein the inlet portion comprises a first cross section and the outlet portion comprises a second cross section, wherein the first cross section is smaller than the second cross section.

16. The roof-mounted exhaust unit of claim 15, further comprising a transition section, the transition section adapting the first cross section of the inlet portion to the second cross section of the outlet portion.