SOUND-REDUCING EXHAUST AIR SYSTEM

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.

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.

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

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 withFIGS.1-6.

FIG.1illustrates a perspective view of an exhaust air system100, according to various embodiments of the present disclosure, andFIG.2illustrates an exploded perspective view of exhaust air system100, according to various embodiments of the present disclosure. Exhaust air system100has an upblast configuration and can be implemented as a roof-mounted exhaust unit. As such, exhaust air system100can be coupled to or otherwise mounted on a roof curb103of a building, warehouse, or other structure (not shown) from which exhaust air system100removes air. Exhaust air system100draws air from an interior space of the building via an air inlet101and discharges the air drawn from the building via an air outlet102. In some embodiments, air inlet101is coupled to ductwork for routing air from one or more interior spaces of the building to exhaust air system100. 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 system100so that additional cooling air can be circulated within the building for further cooling.

In the embodiment illustrated inFIGS.1and2, exhaust air system100includes a bell-mouth110for reducing turbulence associated with air exiting exhaust air system100via air outlet102. By reducing such turbulence, pressure drop (and therefore power consumption) and noise are also reduced. Additionally or alternatively, in some embodiments, a debris guard104is positioned in or on air outlet102. For example, in some embodiments, debris guard104is disposed within bell-mouth110, and in other embodiments, debris guard is disposed at an outlet or top edge112of bell-mouth110. Debris guard104can prevent debris, animals, or other material from entering exhaust air system100. Debris guard104can include a grate or perforated material that permits air to exit bell-mouth110and exhaust air system100with low pressure drop. Additionally or alternatively, in some embodiments, an inlet grate106is positioned above or on air inlet101. In such embodiments, inlet grate106can be configured with sufficiently large cross members such that personnel entering exhaust air system100can stand on inlet grate106when servicing internal components of exhaust air system100. Further, in such embodiments, inlet grate106can be configured with suitably sized openings between cross members so that air can pass through air inlet101and into exhaust air system100with low pressure drop.

Exhaust air system100can 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 system100relative to a conventional exhaust system is significantly less. This is due to reduced pressure drop within exhaust air system100and enhanced airflow that equalizes the workload between the fans of a multiple-fan array within exhaust air system100.

In the embodiment illustrated inFIGS.1and2, exhaust air system100includes a housing120and, disposed within housing120, a vertical fan array130, a turning vane array140, and a deflector plate150. As shown, turning vane array140is disposed within an outlet air plenum122for vertical fan array130and deflector plate150is disposed within an inlet air plenum123for vertical fan array130. Housing120includes a top wall124, side walls125, and a sloped floor126. Sloped floor directs moisture entering exhaust air system100via air outlet102away from air inlet101, thereby reducing the likelihood of water ingress via exhaust air system100. In some embodiments, housing120can be configured with one or more access doors127positioned in side walls125. Access doors127enable access to the interior of exhaust air system100by maintenance or repair personnel. Vertical fan array130, turning vane array140, and deflector plate150are described in greater detail below in conjunction withFIGS.3-6.

FIG.3illustrates a side cutaway view of exhaust air system100, according to various embodiments of the present disclosure, andFIG.4illustrates a top view of exhaust air system100, according to various embodiments of the present disclosure. InFIG.4, top wall124of housing120is omitted for clarity.

Outlet air plenum122is a region of exhaust air system100that is fluidly coupled to air outlet102and inlet air plenum123is a region of exhaust air system100that is fluidly coupled to air inlet101. As shown, outlet air plenum122is disposed downstream of vertical fan array130and receives discharge air302discharged by upper fans331and lower fans332of vertical fan array130. Conversely, inlet air plenum123is disposed upstream of vertical fan array130and receives incoming air303drawn into exhaust air system100by upper fans331and lower fans332of vertical fan array130.

In some embodiments, outlet air plenum122is configured as a sound-absorbing chamber. In such embodiments, outlet air plenum122includes one or more sound-attenuation walls321that absorb or otherwise attenuate fan noise entering outlet air plenum122from vertical fan array130, thereby significantly reducing fan noise exiting exhaust air system100via air outlet102. In some embodiments, sound-attenuation walls321include the side walls125or portions of side walls125forming outlet air plenum122. In some embodiments, sound-attenuating walls321include a portion324of top wall124. In some embodiments, the one or more sound-attenuation walls321include a physical configuration for attenuating sound or a material for attenuating sound. For example, in some embodiments, the one or more sound-attenuation walls321include a perforated surface, sound-dampening slats, and/or an array of sound-absorbing shapes disposed on the interior surfaces of wound-attenuation walls321, such as pyramids, projections, ridges, cavities, and/or the like. Alternatively or additionally, in such embodiments, the one or more sound-attenuation walls321include 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 walls321are lined with such materials, and in other embodiments, such materials are integrated into sound-attenuation walls321.

In the embodiment illustrated inFIGS.3and4, outlet air plenum122includes turning vane array140. As shown, turning vane array140includes a plurality of turning vanes340that are positioned within outlet air plenum122to redirect airflow from vertical fan array130upwards toward the bell-mouth110and air outlet102of exhaust air system100. Thus, turning vanes340are for directing a flow of air generated by vertical fan array130from a horizontal direction311to a vertical direction312. In some embodiments, turning vanes340are positioned to be horizontally and vertically offset from one another such that airflow is directed upwards toward air outlet102with little or no turbulence. As a result, a direction of flow of discharge air302is changed inside exhaust air system100without introducing significant turbulence that can cause significant pressure drop within exhaust air system100and additional noise perceptible outside exhaust air system100.

In the embodiment illustrated inFIGS.3and4, turning vanes340are implemented as curved sheet metal features installed within outlet air plenum122. In other embodiments, turning vanes340can have a different configuration than that illustrated inFIG.3. For example, in some embodiments, turning vanes340can have any technically feasible construction and configuration that facilitates directing the flow of air generated by vertical fan array130from horizontal direction311to vertical direction312. Various embodiments are described below in conjunction withFIGS.5A and5B.

FIG.5Aillustrates a conceptual cross-sectional view of a turning vane541, according to an embodiment of the present disclosure, andFIG.5Billustrates a conceptual cross-sectional view of a turning vane542, according to another embodiment of the present disclosure. As shown inFIG.5A, turning vane541is formed via multiple straight or non-curved segments501and is not configured as a continuous smooth curve. In the embodiment illustrated inFIG.5A, turning vane541is formed via five straight or non-curved segments501. In other embodiments, turning vane541can include any suitable number of straight or non-curved segments501. As shown inFIG.5B, turning vane542includes a two-dimensional cross section, such as an air-foil cross-section, to further reduce turbulence induced in discharge air302when redirected by turning vane542. In other embodiments, turning vane541can include any other two-dimensional cross section suitable for directing airflow from horizontal direction311to vertical direction312.

Returning toFIGS.3and4, in some embodiments, air outlet102is offset from air inlet101in a horizontal direction313so that no portion of air inlet vertically overlaps a portion of air outlet102. As a result, there is no vertical leak path from air outlet102to air inlet101, thereby reducing the likelihood of water ingress via exhaust air system100.

Vertical fan array130is a vertical array of multiple fans that includes at least one upper fan331and at least one lower fan332, where the at least one upper fan is disposed above and adjacent to the at least one lower fan332. In the embodiment illustrated inFIGS.3and4, vertical fan array130is implemented as a 2×2 array, and therefore includes two upper fans331and two lower fans332. In other embodiments, vertical fan array includes more than or fewer than two upper fans331or lower fans332. Upper fans331and lower fans332directing discharge air302in the same direction toward air outlet102, for example through a backdraft damper array338.

According to various embodiments, upper fans331are positioned with a horizontal offset334in horizontal direction313from lower fans332. Thus, in such embodiments, upper fan331are closer to air inlet101in horizontal direction313than lower fans332. In such embodiments, such positioning of upper fans331relative to lower fans332can equalize the workload between upper fans331and lower fans332. Specifically, the presence of horizontal offset334between upper fans331and lower fans332increases the portion of air flowing through upper fans331relative to lower fans332. As a result, for a given total flow of discharge air302discharged by upper fans331and lower fans332, less pressure drop is generated within exhaust air system100during operation. By contrast, when upper fans331are vertically aligned with lower fans332, upper fans331are “starved” of air relative to lower fans332, and therefore cannot contribute to the flow of discharge air302as effectively as lower fans332. It is noted that the magnitude of horizontal offset334is based on multiple factors, including the size and shape of inlet air plenum123, the size and shape of air inlet101, the diameter of upper fans331and lower fans332, the target volume of discharge air302to be discharged from exhaust air system100, the size and shape of deflector plate150, the position of deflector plate150within inlet air plenum123, and/or the like.

Deflector plate150is positioned within inlet air plenum123to modify the flow of incoming air303in a way that can further equalize the workload between upper fans331and lower fans332. According to various embodiments, the presence of deflector plate150upstream of upper fans331and lower fans332increases the portion of air flowing through upper fans331relative to lower fans332. Specifically, deflector plate150at least partially deflects incoming air303after entering air inlet101from vertical direction312to horizontal direction311. As a result, for a given total flow of discharge air302discharged by upper fans331and lower fans332, less pressure drop is generated within exhaust air system100during operation.

In the embodiment illustrated inFIGS.3and4, deflector plate150is implemented as a flat plate that is disposed within inlet air plenum123. In the embodiment, a leading edge351of deflector plate150is coupled to an edge352of air inlet101and a trailing edge353of deflector plate150is coupled to top wall124of inlet air plenum123. In the embodiment illustrated inFIG.3, deflector plate150prevents the flow of incoming air303from passing through an eddy region255of inlet air plenum123. Thus, turbulence and the concomitant pressure drop within exhaust air system100is reduced. Generally, the size, shape, and position of deflector plate150can be selected based on multiple factors, including the size and shape of inlet air plenum123, the size and shape of air inlet101, the diameter of upper fans331and lower fans332, the target volume of discharge air302to be discharged from exhaust air system100, the magnitude of horizontal offset334, and/or the like.

In the embodiment illustrated inFIGS.3and4, deflector plate150is implemented as a flat plate. Alternatively, in some embodiments, deflector plate150is implemented as a curved plate disposed within inlet air plenum123. One such embodiment is illustrated inFIG.6.

FIG.6illustrates a side cutaway view of exhaust air system100showing a curved deflector plate650, according to various embodiments of the present disclosure. As shown, curved deflector plate650is disposed within inlet air plenum123. Further, a leading edge651of deflector plate650is coupled to edge352of air inlet101and a trailing edge653of deflector plate650is coupled to top wall124of inlet air plenum123. In the embodiment illustrated inFIG.6, deflector plate650prevents the flow of incoming air303from passing through an eddy region655of inlet air plenum123. Thus, turbulence and the concomitant pressure drop within exhaust air system100is reduced. Similar to deflector plate150ofFIG.3, the size, shape, and position of deflector plate650can be selected based on multiple factors, including the size and shape of inlet air plenum123, the size and shape of air inlet101, the diameter of upper fans331and lower fans332, the target volume of discharge air302to be discharged from exhaust air system100, the magnitude of horizontal offset334, and/or the like.

Returning toFIGS.3and4, in operation, incoming air303enters air inlet101vertically from a roof penetration and/or a duct (not shown) through inlet grate106, and deflector plate150deflects incoming air303toward vertical fan array130. As described above, deflector plate150is positioned to reduce pressure drop across exhaust air system100by maintaining more even airflow across vertical fan array130. Discharge air is302is discharged by upper fans331and lower fans332in horizontal direction311, flows through turning vanes340, and is directed into vertical direction312and through air outlet102.

In an example embodiment, vertical fan array130is implemented as a 2×2 array and exhaust air system100is 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 system100can 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.