US20220349613A1

US20220349613A1 - Supply air duct with integral nozzles for diffusing supply air along the length of the supply air duct

Info

Publication number: US20220349613A1
Application number: US17/242,432
Authority: US
Inventors: William Brian Griffin; Nicholas I. Perry; Kyle D. Thompson; Joshua J. Hess
Original assignee: Captive Aire Systems Inc
Current assignee: Captive Aire Systems Inc
Priority date: 2021-04-28
Filing date: 2021-04-28
Publication date: 2022-11-03
Also published as: WO2022231895A1; EP4330605A1; AU2022264377A1; CA3216758A1

Abstract

An exposed high induction supply air duct is provided and is adapted to be installed in an open ceiling environment. Conditioned air is diffused from the supply air duct through an array of nozzles disposed along the length of the supply air duct. At the same time, existing air in an open space underlying the duct is induced upwardly towards the nozzles where the existing air is efficiently mixed with the supply air being exhausted by the nozzles.

Description

FIELD OF THE INVENTION

The present invention relates to heating, ventilation, and air conditioning (HVAC) systems and more particularly to a supply air duct used in HVAC systems.

BACKGROUND OF THE INVENTION

Conventional supply air ducts, such as spiral ducts, commonly used today in commercial buildings to supply air to a space being heated and cooled have many disadvantages and shortcomings. First, insulation is difficult, complicated, and extremely time consuming. For example, many of the conventional supply air ducts require cutting and sealing on site. Secondly, most conventional supply air ducts rely on independently sourced diffusers that are secured to the duct or otherwise communicatively connected with the duct. The spacing and location of the diffusers are often haphazardly located with little or no engineering analysis. This results in the inefficient mixing of supply air with existing air in the space being heated or cooled, all of which leads to a non-uniform diffusion of supply air, hot and cold spots as well as temperatures stratification in the space being heated and cooled.

SUMMARY OF THE INVENTION

The supply air duct shown and described herein overcomes these disadvantages and shortcomings of conventional supply air ducts. The supply air duct disclosed is designed to provide high induction and linear diffusion of the supply air, which means that the entire or at least most of the duct system is diffusing air to the space in a uniform fashion, without the use of add-on diffusers. The high induction flow means that the continuous duct linear diffusion pattern causes the rapid mixture of the supply air with the air in the space, bringing the space to set point conditions more quickly than conventional supply air ducts.
The design of the supply air duct entails nozzles in the outer walls of the duct and spacing and arranging the nozzles linearly along most of the length of the duct. In one embodiment, openings in the outer wall that form the nozzles are sized to cause jet streams of supply air to be emitted from the supply air duct. This can lead to a negative pressure around the supply air duct and nozzles, which tends to induce existing air in the space to move towards the duct and nozzles where the existing air is efficiently mixed with the jet streams of supply air being emitted by the duct.
In one embodiment, the supply air duct is designed to enhance the mixing of supply air and existing air in an open space and generally comprises:
a series of duct sections secured together in end-to-end relationship which forms the supply air duct;
the supply air duct configured to contain pressurized supply air and configured to be suspended or supported in the open space for heating and cooling the open space;
an array of nozzles in the outer wall of the supply air duct and configured to disperse the pressurized supply air from the supply air duct in the form of an array of jet streams;
the array of nozzles formed in a generally linear direction along the length of the supply air duct and including nozzles arranged in rows and generally uniformly spaced along the length of the supply air duct; and
the array of nozzles configured to disperse the pressurized supply air through the nozzles and generally uniformly along the length of the supply air duct.
Another embodiment entails a method of dispersing supply air to an open space for heating and cooling the open space. The method comprises:
suspending or supporting a supply air duct over the open space;
directing pressurized conditioned supply air into and through the supply air duct;
dispersing the conditioned supply air from the supply air duct generally uniformly along the length of the supply air duct by:
dispersing jet streams of the conditioned supply air from the supply air duct through an array of nozzles in the outer wall of the supply air duct; and
wherein the array of nozzles is generally uniformly spaced and extend in a generally linear direction along the length of the supply air duct.
Other objects and advantages of the present invention will become apparent and obvious from a study of the following description and the accompanying drawings which are merely illustrative of such invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an HVAC system including a supply air duct and a return air duct.

FIG. 2 is a schematic elevational view illustrating the placement of the supply air duct in an upper corner area of the space being heated and cooled.

FIG. 2-1 is a side elevational view of a duct section showing an array of nozzles employed in the supply air duct shown in FIG. 2.

FIG. 2-2 is a schematic illustration of a duct section illustrating the area generally occupied by the nozzles in the supply air duct shown in FIG. 2.

FIG. 2A is a schematic elevational view illustrating the placement of the supply air duct in an upper center area of the space being heated and cooled.

FIG. 2A-1 is a bottom view of the duct section employed in the supply air duct shown in FIG. 2A.

FIG. 2A-2 is a schematic illustration of the duct section showing the area occupied by the nozzles in the supply air duct shown in FIG. 2A.

FIG. 2B is a view similar to FIG. 2A except that the supply air duct is provided with two groups of spaced apart nozzles.

FIG. 2B-1 is a bottom view of the duct section employed in the supply air duct shown in FIG. 2B.

FIG. 2B-2 is a schematic illustration of the area occupied by the nozzles in the supply air duct shown in FIG. 2B.

FIG. 2C is a schematic elevational view showing the placement of the supply air duct in an upper central area of the space and wherein the supply air duct is provided with two groups of nozzles spaced 180° apart.

FIG. 2C-1 is a side view of a duct section employed in the supply air duct shown in FIG. 2C.

FIG. 2C-2 is a schematic illustration showing the area occupied by the nozzles in the supply air duct shown in FIG. 2C.

FIG. 3 is a perspective view of an alternative design for the supply air duct wherein the diameter of the supply air duct is stepped down towards a remote end thereof.

FIG. 4 is a schematic illustration showing the mixing of supply air emitted by the nozzles and existing air in the space.

FIG. 5A shows two duct sections and a securing band prior to the two duct sections being connected.

FIG. 5B shows the two duct sections connected together by the securing band.

FIG. 6A is a fragmentary sectional view showing portions of the two duct sections prior to being coupled together.

FIG. 6B is a fragmentary sectional view showing a portion of the two ducts being secured together by the securing band.

DESCRIPTION OF EXEMPLARY EMBODIMENTS

With further reference to the drawings, particularly FIG. 1, an HVAC system is shown therein and indicated generally by the numeral 10. HVAC system 10 comprises a dedicated outdoor air system 11 for heating and cooling outside air and directing the heated or cooled air into a supply air duct 12. In addition, the HVAC system includes a return air duct 14.
The focus of this invention is on the supply air duct 12. Supply air duct 12 can be employed with various types and forms of HVAC systems. Thus, the dedicated outdoor air system 11 shown in FIG. 1 is just one example of an HVAC unit that can be used with the supply air duct 12.
Supply air duct 12 includes a plurality of duct sections 12A. Duct sections 12A are joined end-to-end to form the supply air duct 12. As will be explained later, when the respective duct sections 12A are connected end-to-end, an airtight seal is formed. Likewise, the return air duct 14 includes a plurality of duct sections 14A that are connected in end-to-end relationship. Note in FIG. 1 where the return air duct 14 includes a return air inlet 14B formed in the remote end of the return air duct.
Supply air duct 12 is designed to disperse supply air generally uniformly along the length of the supply air duct. Thus, as seen in the drawings, the supply air is linearly dispersed along the length of the supply air duct 12. Furthermore, the supply air duct 12 is a high induction duct. By high induction, it is meant that the existing air in the open space below the exposed supply air duct 12 is induced to move towards the supply air duct where the existing air efficiently mixes with the supply air being dispersed from the duct.
Supply air duct 12 includes an array of nozzles 18 in the outer wall of the duct. In the examples shown in the drawings, the nozzles 18 are disposed in rows. In some examples, the nozzles may reside in a single row and in other examples the nozzles may be arranged in a plurality of rows. The nozzle configuration is not limited to aligned row configurations. Other nozzle patterns are contemplated. However, whatever nozzle pattern is employed, the nozzles are provided along the length of the supply air duct 12. In the example shown in FIG. 2-1, there are four rows of nozzles in the outer wall of the supply air duct. In the example shown in FIG. 2B, the nozzles 18 are grouped into two sets of nozzles with each set comprising two rows of nozzles. It is appreciated that the nozzles 18 can be grouped in two or more sets, and the spacing between the sets can vary. The nozzles are generally uniformly spaced with respect to each other.
Nozzles 18 are formed, in one embodiment, by openings in the outer wall of the supply air duct 12. The size or diameter of the openings can vary.
Supply air directed from the HVAC unit 11 into the supply air duct 12 is pressurized. The pressure in the supply air duct 12 can vary. The pressure inside the supply air duct 12 can be measured in water column and can vary.
Nozzles 18 effectively resist the flow of supply air from the supply air duct 12. Nozzles 18 give rise to a Venturi effect. That is, in the course of restricting the flow of supply air, the velocity of the supply air exhausted by the nozzles 18 increases. This results in the supply air in the supply air duct 12 being dispersed in jet streams into the open space being heated or cooled.
In one embodiment, the nozzles 18 extend continuously along a substantial length of the supply air duct 12. The length of the supply air duct is defined to be the length between the first and last nozzle or nozzles. This means that the length of the supply air duct does not include feed sections extending from the HVAC unit to where the first nozzles are located. In some embodiments, the nozzle pattern formed in the supply air duct may not be continuous. For example, in some cases, not all of the duct sections 12A in the supply air duct include nozzles. For example, in some embodiments, the nozzles may be provided in every other duct section 12A. The nozzle pattern should extend over a substantial length of the supply air duct. It is preferable that at least 50% of the length of the supply air duct include a nozzle pattern for dispersing supply air.
Because the nozzles 18 emit a jet stream of supply air, a negative pressure is generated immediately adjacent the exterior side of the nozzles. That is, there is a small pressure differential that exists between the open space generally and the area immediately adjacent the nozzles 18. This gives rise to the induction feature of the supply air duct 12. Because of this negative pressure, existing air in the open space tends to be induced or swept upwardly toward the supply air duct 12 and particularly to areas adjacent the nozzles 18. This is schematically shown in FIG. 4. Here the existing air is represented by arrows whose tails are dotted while the supply air is represented by full arrows. This is one example of a flow pattern for the supply air and the existing air. These flow patterns can vary depending on numerous factors, such as the location of the supply air duct 12 in the open space, the arrangement of nozzles in the supply air duct, the spacing and size of the openings that form the nozzles 18, as well as other factors. In any event, this results in the efficient mixing of existing air with the jet streams of supply air being emitted by the nozzles 18. This efficient mixing of supply air with existing air in the space being heated or cooled provides a uniform diffusion of supply air into the open space and avoids hot and cold spots, as well as temperature stratification in the space being heated or cooled.
Supply air duct 12 is designed to be employed in an open ceiling environment where the duct is exposed in the open space. As the drawings indicated, the supply air duct can be located at various locations in the open space. For example, see FIGS. 2, 2A, 2B and 2C. In these cases, the supply air duct 12 is suspended or supported in an upper portion of the open space. In FIG. 2, the supply air duct 12 is supported in an upper corner area of the open space. In this particular example, the nozzle pattern includes four rows of nozzles. See FIG. 2-1. The nozzle pattern extends approximately 45° around the duct. Note in FIG. 2 where the nozzle pattern is located generally in the 4:00-5:00 o'clock position such that the jet streams of supply air are directed generally outwardly and slightly downwardly from the supply air duct 12.
In FIG. 2A, the supply air duct 12 is disposed in an upper center area of the open space. In this example, the nozzle pattern includes four rows and are provided over approximately a 45° of the supply air duct. See FIGS. 2A-1 and 2A-2. Note in the FIG. 2A example where the nozzle pattern is generally centered at the 6:00 o'clock position such that the jet streams of supply air are directed downwardly.
Turning to the example shown in FIG. 2B, the supply air duct 12 is again located in the upper center of the open space. However, in this example, the supply air duct is provided with two sets or groups of nozzles 18. See FIG. 2B-1. Note in FIG. 2B where the jet streams of supply air are directed generally downwardly and slightly outwardly from the two sets of nozzles.
The example shown in FIG. 2C is similar in some respects to that shown in FIG. 2B. Here again, the supply air duct 12 is disposed in an upper central portion of the open space. Supply air duct 12 is provided with two sets or groups of nozzles 18. These two sets of nozzles are generally separated by 180°. As seen in FIG. 2C, the two sets of nozzles provide an array of jet streams of supply air from both sides of the supply air duct 12. That is, the jet streams are directed generally horizontally from opposite sides of the supply air duct 12.
The open space containing the supply air duct 12 will include what is termed an occupied area or space (occupiable area) where people work, congregate, move through, etc. The velocity of the supply air emitted by the nozzles 18 is typically greater than what is appropriate for the occupiable area. Thus, the HVAC system 10 and particularly the supply air duct 12 is designed to assure that the velocity of the supply air reaching the occupiable area is below a selected threshold. In one example, the threshold is approximately 50 feet per minute. So, in this case, the openings forming the nozzles 18 are particularly sized, spaced and arranged with respect to the HVAC system as a whole to assure that the velocity of the supply air reaching the occupiable area is less than the selected threshold which in this example is 50 feet per minute. FIGS. 2, 2A, 2B and 2C show the supply air being emitted by the nozzles 18. But the supply air in each case is surrounded by a dotted line envelope. In this example, the velocity of the supply air outside of this envelope should be less than the threshold value.
Turning to FIGS. 5A and 5B, details of the duct sections 12A are shown. Duct sections 12A can be constructed of various materials. In one embodiment, stainless steel is employed. Each duct section includes a main cylindrical body 12A1 and a pair of outwardly projecting flanges 12A2 and 12A3. At least some of the duct sections 12A have an integral gasket 20 incorporated into the duct section when fabricated. The term “integral gasket” means that the gasket is incorporated into the duct section during fabrication of the duct section and not at the installation site. This alleviates problems associated with installing or incorporating a gasket during on-site installation. Gasket 20 is secured to the outer side of at least one of the flanges 12A2 or 12A3. In one embodiment, both flanges 12A2 and 12A3 include the integral gasket 20. Various materials can be used for the gasket 20. In a preferred embodiment, the gasket comprises an ethylene propylene diene monomer rubber (EPDM) foam gasket. EPDM is blended with neoprene and styrene-butadiene rubber (SPR) to create a foam that offers excellent resistance to water and wear.
In one embodiment, one duct section 12A having the integral gasket 20 is connected to another duct section that does not include the integral gasket. See FIG. 5A. The duct section 12A on the left includes the integral gasket 20 but the duct section to the right does not include the integral gasket. In any event, the two duct sections are brought together and the flange 12A2 of the rightmost duct section is butted against the gasket 20 secured to flange 12A2 on the leftmost duct section. To secure the two duct sections together, a V-band 22 is employed. As shown in FIGS. 6A and 6B, the V-band spans the two flanges and the gasket 20 and is tightly secured around the joint formed by the two flanges 12A2 and the gasket 20. As seen in the drawings, flanges of the two duct sections are inside the V-band 22. Once the V-band 22 is disposed around the joint, it is tightened so as to effectively secure one duct section to another duct section.
In many instances, the diameter of the supply air duct 12 is constant throughout its length. There may be cases where it is desirable to step down the diameter of the supply air duct 12 along its length. One example of this is shown in FIG. 3 where the supply air duct 12 includes three duct sections of one diameter and three duct sections of another diameter. This can be helpful in particularly designing the supply air duct for a particular application and in cases where varying the diameter can facilitate a final design that emits a more generally uniform distribution of supply air along the length of the supply air duct.
There are many advantages of supply air duct 12. Supply air emitted from the supply air duct is more laminar and evenly distributed into the open space being heated or cooled. Further, the supply air duct is a high induction supply air diffuser. High induction means that the continuous linear diffusion pattern causes rapid mixture of the supply air with the existing air in the open space, bringing the open space to setpoint conditions much more quickly than conventional supply air ducts. Supply air duct 12 also has enhanced aesthetics, particularly when constructed of stainless steel. This highly finished appearance for open ceiling or industrial use makes the supply air duct of the present invention appealing in restaurants, breweries, and commercial and industrial buildings.
Moreover, the duct sections 12A are field-ready for installation at the installation site. No metal cutting is required and there is no requirement to install seals or gaskets. This is because the individual duct sections 12A come with an integral gasket. Thus, it is just a matter of aligning respective duct sections 12A together and coupling them together with a V-band 22.
The term “configured to” is used herein and in the claims. The term “configured to” means “designed to”. It does not mean “capable of” or “adapted to”. Hence, the use of “configured to” with reference to a component or element of the invention means that such component or element is specifically designed to perform a recited function.
The present invention may, of course, be carried out in other specific ways than those herein set forth without departing from the scope and the essential characteristics of the invention. The present embodiments are therefore to be construed in all aspects as illustrative and not restrictive and all changes coming within the meaning and equivalency range of the appended claims are intended to be embraced therein.

Claims

What is claimed is:

1. A method of dispersing conditioned supply air to an open space for heating and cooling the open space, the method comprising:

suspending or supporting a supply air duct over the open space;

directing pressurized conditioned supply air into and through the supply air duct;

dispersing the conditioned supply air from the supply air duct generally uniformly along the length of the supply air duct by:

dispersing jet streams of the conditioned supply air from the supply air duct through an array of nozzles in the outer wall of the supply air duct; and

wherein the array of nozzles is generally uniformly spaced and extend in a generally linear direction along the length of the supply air duct.

2. The method of claim 1 wherein the nozzles are formed by openings in the outer wall of the supply air duct and wherein the open space includes an occupiable area; and wherein the method includes sizing the openings and arranging the spacing of the openings such that the velocity of the jet streams of the supply air is less than 50 feet per minute in the occupiable area.

3. The method of claim 1 further including:

as the jet streams of the pressurized supply air are dispersed through the nozzles, the method includes generating a negative pressure around the supply air duct and the nozzles therein;

inducing existing air in the open space to be drawn into the negative pressure area; and

mixing the jet streams of supply air with the existing air in the negative pressure area.

4. The method of claim 1 wherein the nozzles include two groups of spaced apart nozzles;

and the method includes dispersing conditioned supply air from each group of the nozzles into the open space.

5. The method of claim 1 wherein the supply air duct includes a plurality of duct sections secured end-to-end; each duct section including outwardly extending flanges on opposite ends thereof; wherein selective duct sections include at least one gasket permanently secured to an outer side of one flange; and wherein connecting the duct sections end-to-end forms a joint comprising a pair of flanges from two different duct sections and the gasket interposed therebetween and wherein there is a securing band that extends around the joint and effectively secures the two duct sections together.

6. An exposed supply air duct designed to enhance the mixing of supply air and existing air in an open space containing the supply air duct, comprising:

a series of duct sections secured together in end-to-end relationship which forms the supply air duct;

the supply air duct configured to contain pressurized supply air and configured to be suspended or supported in the open space for heating and cooling the open space;

an array of nozzles in the outer wall of the supply air duct and configured to disperse the pressurized supply air from the supply air duct in the form of an array of jet streams;

the array of nozzles formed in a generally linear direction along the length of the supply air duct and including nozzles arranged in rows and generally uniformly spaced along the length of the supply air duct; and

the array of nozzles configured to disperse the pressurized supply air through the nozzles and generally uniformly along the length of the supply air duct.

7. The supply air duct of claim 6 wherein the nozzles are split into two or more spaced apart groups of nozzles with each group of nozzles extending generally linearly along the length of the supply air duct.

8. The supply air duct of claim 6 wherein each duct section includes a flange formed on opposite ends thereof; and wherein at least some of the duct sections include a gasket permanently secured to an outer side of at least one flange.

9. The supply air duct of claim 6 wherein the supply air duct is disposed in an upper portion of an open space;

a negative pressure area formed around the supply air duct and the nozzles; and

wherein the negative pressure area induces the existing air in the open space to move into the negative pressure area and mix with the jet streams of the supply air being discharged by the nozzles.

10. The supply air duct of claim 8 wherein the supply air duct includes a series of spaced apart securing bands that secure the duct sections together in end-to-end relationship; and wherein each securing band extends around a joint formed by a pair of opposed flanges of a pair of duct sections and the gasket interposed being between the two opposed flanges.