WO2008058334A1

WO2008058334A1 - Plenum chamber

Info

Publication number: WO2008058334A1
Application number: PCT/AU2007/001754
Authority: WO
Inventors: Noel V. Holyoake
Original assignee: Holyoake Industries (Vic) Pty Ltd
Priority date: 2006-11-16
Filing date: 2007-11-16
Publication date: 2008-05-22
Also published as: AU2007321712A1

Abstract

There is disclosed a plenum chamber (18) for use adjacent a diffuser (19) or the like of a heating, ventilating or air conditioning system The plenum chamber (18) includes a body (26) defining a space for receiving air supplied from a duct of the beating, ventilating or air conditioning system. An inlet (30) is connectable to the duct for delivering the air into the space. An outlet (29) is also provided through which air passes from the space to the diffuser (19). A flow disturbing element (32) is located within the space such that air delivered into the space through the inlet (30) impinges upon a surface of the flow disturbing element (32) to disturb the flow of said air in said space to facilitate mixing and pressurisation of said air within the space as the air passes to the outlet (29).

Description

PLENUM CHAMBER

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority from Australian Provisional Patent Application No 2006906398 filed on 16 November 2006, and Australian Provisional Patent Application No 2007904150 filed on 3 August 2007 the contents of which are incorporated herein by reference. FIELD OF THE INVENTION

The present invention relates to heating, ventilation and/or air conditioning systems and in particular, to a device for distributing air to a diffuser of such systems for controlled release into an occupied space. BACKGROUND

A variety of healing, ventilation and air conditioning (HVAC) systems are known for delivering and/or circulating air through a building, such as a home or office. Typically, such systems employ a centralised air conditioner unit that conditions the air to achieve a desired temperature and/or humidity prior to delivery of the air to one or more rooms of the buildtng by way of a delivery fan or the like. The fan typically propels the air through a network of ducts located within a space in the ceiling or floor of the building, whereby the pre-conditioned air or supply air enters the room through an outlet or diffuser/register located in the ceiling/wall/floor of the room. The supply air is then distributed around the room in accordance with the comfort requirements of the occupants of the room.

The diffuser is typically designed to provide uniform throw and coverage of the supply air into the room so as to achieve desired air distribution. In this regard, the diffuser typically employs blades, louvres and the like, which assist in directing the supply air so as to achieve a desired flow pattern or direction as it exits therefrom. Such an arrangement acts to evenly distribute the air throughout the room without creating uncomfortable draughts or excessive noise, which may adversely affect the comfort of the occupants of the room.

To connect the diffuscr to the supply ducts of the system, a plenum chamber may be employed, which is sometimes referred to in the industry as a plenum box or a cushion head box. The plenum chamber is typically in the form of a box that acts as an air buffer for introducing the supply air to the diffuser. Conventional plenum chambers are typically constructed from sheet metal. They may be insulated to minimise heat loss from or gain by the supply air received therein. The chamber typically receives the supply air through an inlet aperture in a side wall thereof where the supply duct is connected, with the diffuser being typically mounted at an outlet in a bottom surface of the chamber, so as to be flush with a ceiling or the like when the plenum chamber is installed for use. Due to flow characteristics of air when delivered to the plenum chamber under pressure, the supply air typically flows along the internal wall of the plenum chamber, opposite the inlet aperture, before exiting from the diffuser. Hence, an excessively large proportion of the supply air preferentially exits through one side of the diffuser, namely that side adjacent the chamber wall opposite the inlet, which can significantly affect the intended operation or efficiency of the diffuser and the air flow conditions within the room.

To prevent such conditions from occurring, plenum chambers have been fitted with internal perforated screens upstream of or adjacent the diffuser to limit the volume of air that may pass therethrough such that the air is mixed and more equally distributed across the surface of the diffuser. However, such a screen has been found to create substantial back pressure within the HVAC system, placing a greater load on the circulating fan of the system, as well as generating more noise as the air passes through the screen. There exists a need to provide a device that facilitates improved distribution of supply air from a supply duct to a diffuser, or the like, preferably without considerably compromising the efficiency of the system or contributing to an increase in the noise of the HVAC system. Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present invention. Tt is not to be taken as an admission that any or all of these matters fomi part of the prior art base or were common general knowledge in the field relevant to the present invention as it existed before the priority date of each claim of this application.

SUMMARY OF THE INVENTION

According to a first aspect, the present invention provides a plenum chamber for use adjacent a diffuser or the like of a heating, ventilating or air conditioning system, including: a body defining a space for receiving air supplied from a duct of the heating, ventilating or air conditioning system; an inlet connectable to the duct for delivering the air into the space; an outlet through which air passes from said space to said diffuser; and a flow disturbing element located within said space such that air delivered into said space through the inlet impinges upon a surface of the flow disturbing element to disturb the flow of said air in said space to facilitate mixing and pressurisation of said air within the space as the air passes to the outlet. in one embodiment, the flow disturbing element is positioned generally opposite said inlet such that air is directed by said inlet to the surface of the flow disturbing element. In this regard, the inlet and outlet may extend in different directions. The outlet may extend in an orthogonal direction to said inlet such that the air delivered into the space through said inlet takes a 90° turn before exiting through the outlet.

The surface of the flow disturbing element may have at least one concave region in combination with at least one convex region. The surface of the flow disturbing element may be continuous such that the at least one concave region and the at least one convex region combine to form a continuous curved surface. The continuous curved surface may comprise a first concave region and a second concave region connected by a convex region. The first concave region may be positioned to substantially face the inlet such that a majority of the air flow delivered by the inlet impinges upon the first concave region to disturb the air flow within the space to facilitate mixing of the air downstream of the convex region.

In another embodiment, the body is in the form of a box. The box may have a roof and four side walls extending in a downward direction from said roof. A floor of the box may be open, thereby forming the outlet of the plenum chamber. The inlet may be provided in one of the side walls. The inlet may be a tubular member configured to engage with the duct of the heating, ventilating or air conditioning system. Alternatively, the inlet may be a hole or spigot formed in the side wall of the body. The inlet may be configured to deliver the air into the space at an angle such that the air is directed towards the outjet. The inlet may be disposed at an angle of between around 5° - 25° to the horizontal. The body may be moulded from a polymeric material, such as expanded polystyrene.

In one embodiment, the flow disturbing element may be formed integral with the body during the moulding of the body. In this regard, the flow disturbing element may be an internal wall of the body. In another embodiment, the flow disturbing element is formed separately to said body and assembled with the body during manufacture or after manufacture of the body. The flow disturbing clement may be attachable to an inner wall of the body.

According to a second aspect, the present invention provides a method of handling air for delivery to a diffuser or the like of a heating, ventilating or air conditioning system comprising: receiving air from a supply duct into a space, said air being received at a supply pressure; collecting at least a portion of said air within the space such that the air within the space is pressurised to a level at or below said supply pressure; and delivering said air from said space and through an outlet under action of the supply pressure.

The step of collecting at least a portion of the air may include mixing the air within the space. The air may be mixed within said space by directing the air onto a flow disturbing element located within said space such that air received into said space impinges upon a surface of the flow disturbing element to disturb the flow of said air in said space to facilitate mixing and pressurisation of said air within the space. A pressure differential may then be created between the air supplied to the space and the air collected in the space and this pressure differential may cause the air to be delivered from the space and through the outlet. Throughout this specification the word "comprise", or variations such as

"comprises" or "comprising", will be understood to imply the inclusion of a stated clement, integer or step, or group of elements, integers or steps, but not the exclusion of any other clement, integer or step, or group of elements, integers or steps. BRTEF DESCRIPTION, OF THE DRAWINGS

By way of example only, preferred embodiments of the invention are now described with reference to the accompanying drawings, in which:

FlG. I is a simplified block diagram of a HVAC system in accordance with the present invention;

FIG. 2A is a perspective view of a prior art plenum chamber;

FIG 2B is a cross-sectional side view of the plenum chamber of FIG. 2A;

FIG. 3 is a cross-sectional side view of a plenum chamber in accordance with one embodiment of the present invention; FIGS. 4Λ and 4B arc plan and cross-sectional side views respectively of a plenum chamber in accordance with an alternative embodiment of the present invention;

FIG. 5 is a cross-sectional side view of an embodiment of a detachable flow disturbing element of lhe present invention;

FIG. 6 is a cross-sectional side view of a body of a plenum chamber with flow disturbing element detached in accordance with an alternative embodiment of the present invention;

FIG. 7 is a cross-sectional side view of the body of the plenum chamber of FIG. 6 with the flow disturbing element of FIG. 5 assembled therein;

FIGS 8A and 8B are enlarged views of FtG. 7 showing the manner in which the flow disturbing element of FIG. 5 is attached to the body of FIG. 7;

FIGS. 8C and 8D are enlarged views of FIG. 7 showing the manner in which the open end or bottom of the body of FIG. 7 is configured to receive a variety of diffusers/grilles; and FIG. 9 is a cross sectional side view of the plenum chamber of FIG. 7 showing the manner in which air flow is controlled to pressurise the chamber for controlled air distrubution therefrom.

DETAILED DESCRIPTION OF AN EXEMPLARY EMBODIMENT OF THE PRESENT INVENTION

The present invention will now be described in relation to its application to a centralised ducted heating, ventilation or air conditioning (HVAC) system 20. However, it will be appreciated by those skilled in the art that the present invention could be incorporated into a variety of different types of HVAC systems which employ a number of conditioning units and fans, other than that shown.

The simplified HVAC system 20 as shown in Figure 1 represents the most common type of system used in larger office buildings. Typically, a room 12 of the building 10 defines an occupied space or work area and the temperature of the air within the room 12 is controlled by a thermostat (not shown) to be maintained at a desired comfort level. Upon the thermostat detecting a difference between the actual temperature of the air and the desired comfort temperature, control signals are sent to the HVAC system 20 to adjust the temperature of the air entering the room and/or the volume of air entering the room such that upon mixing with the other air in the room, the temperature is maintained at the desired comfort level. Whilst the building 10 housing the system 20 is shown as having a single room 12, it will be appreciated that the system 20 could be readily adapted to accommodate a large number of rooms 12.

The HVAC system 20 comprises an intake inlet 13 through which fresh air is drawn from outside the building !0 and where appropriate mixed with return air, A variety of filters (not shown) may be provided with the intake inlet 13 to remove particles of dust, dirt, pollen, etc. from the air prior to conditioning. The fresh air supply then passes along an intake duct 11 where it is presented to cooling coils 14 and heating coils 15 to alter the temperature of the air in accordance with the needs of the system 20.

In this regard, should the thermostat provided in the room 12 detect that cool air is required in order to achieve the desired comfort level, the cooling coils 14 may be activated to cool the supply air. The cooling coils 14 may comprise one or more coils arranged within the air stream of the supply air through which a refrigerant or water is passed which cools the supply air as it travels therethrough. Similarly, should the thermostat provided in the room 12 detect that warm air is required in order to achieve the desired comfort level, the heating coils 15 may be activated to heat the supply air. The heating coils 15 may comprise one or more coils arranged within the air stream of the supply air through which hot water may be passed or banks of electric heating elements provided to heat the supply air as it travels therethrough. Tt will be appreciated that such conditioning systems arc well known in the art and may further include air-dehumidifying units to remove moisture from the supply air.

Following conditioning of the supply air, a supply fan 16 is provided to circulate the conditioned supply air and deliver the supply air to the room 12. The supply fan 16 is configured to provide both the force to draw the air through the cooling coils 14 and heating coils 15 and to propel the conditioned supply air along a supply air duct 17 to the room 12.

The supply air duct 17 is typically installed within a ceiling space of the building 10. The duct 17 is made from sheet metal and covered in an insulating layer in order to minimise uudesired heat loss or gain through the walls of the duct 17, as well as to reduce the costs of running the system and to reduce noise generated within the system. In this regard, the duct 17 may also incorporate a vapour barrier in the form of a moisture proof layer of material, which prevents humid air from reaching a cold surface of the duct 17. This in turn prevents humid air from condensing on the cold surfaces of the duct 17, which could lead to corrosion of the duct surface and premature failure of the system 20, and in some instances, damage to the building 10. The supply air duct 17 extends from the supply fan 16 to the room 12 and terminates at a plenum chamber 18 having a diffuscr 19 attached to an undersurface thereof. As is shown, the plenum chamber 18 is attached to the ceiling of the room 12 such that the diffuscr 19 faces into the interior of the room 12, through a recess (not shown) formed in the ceiling. The plenum chamber 18 (or cushion head chamber) is directly connected to an end of the duct 17 and provides an air buffer prior to introducing the supply air to the diffuser 19. It will be appreciated that the diffuser 19 could take a variety of forms in which to distribute air evenly throughout the room 12, and typically the diffuser 19 comprises a plurality of blades or the like which assist in directing and distributing the air as it flows therefrom. The plenum chamber 18 of the present invention will be discussed in more detail below.

To facilitate air circulation throughout the building 10, an extract port 21 is provided in the room 12 to extract air from the room t2. The extracted air may be removed from the system 20 or further circulated within the building 10 as appropriate. As shown, the extract port 21 is provided in the wall of the room 12 and is connected to an extract fan 23 by way of extract duct 22.

The extract fan 23 can deliver the extracted air to the exhaust outlet 24 such that the air is discharged from the building, or the extracted air may be delivered to the intake duct 11 to be recycled back into the inlet system via a return air duct 25. Return air duct 25 provides an interconnection between the intake duct 11 and extract duct 22 which allows a controlled amount of air to recirculatc around the air conditioning system 20 when full fresh air is not required.

Referring to Figures 2A and 2B. a plenum chamber 40 is shown which is representative of an existing plenum chambeT arrangement that may be employed with a variety of HVAC systems. The plenum chamber 40 is made from sheet metal, and insulated to avoid heat loss and condensation between the supply air and the plenum chamber. The plenum chamber has a body 41 in the form of a box having four side walls 42, a roof 43 and an open floor that forms an outlet 44, to which is mounted a diffuser 19. An inlet 45 is provided in one of the side walls 42, which is connectable to a supply duct 17 of the HVAC system of Figure 1. The inlet 45 is shown as tubular, however it will be appreciated that the shape of the inlet can vary in accordance with the duct 17 to facilitate connection therebetween.

The inlet 45 receives the supply air under pressure from the supply fan 16 and delivers the supply air into the body 41. As shown more clearly in FTG. 2B, the interior of the body 41 is configured to direct the supply air through a substantially 90° turn such that the supply air exits the outlet 44, and passes through the diffuser 19 and into the room. To assist in directing the air through the 90° transition, a guide member 46 is provided within the body 41. The guide member 46 as shown is an insert, such as a curved sheet of metal, that is positioned within the body 41 to provide a concave surface along which the supply air can travel towards the outlet 44. However, it will be appreciated that the guide member 46 may be an integral wall formed in the body 41. The guide member 46 extends from the roof 43 of the body 41 adjacent the side wall 42 which accommodates the inlet 45, to the open floor of the body 41 adjacent the side wall 42 opposite the inlet 45. In this regard, the guide member 46 extends across the path of the supply air and forms a curved elbow within the body 41. This elbow within the body 41 ensures that the supply air contacts the concave surface of the guide member 46 and is directed through a substantially 90° arc along the surface of the guide member, to the outlet 44. where it is able to pass through the diffuser 19.

Λ problem with such an arrangement of the plenum chamber 40 is that the supply air assumes a laminar flow path along the concave surface of the guide member 46. This results in an excess proportion of the supply air exiting the outlet 44 along the bottom edge of the side wall 42 opposite the inlet 45. Therefore, the supply air is presented to the diffuser 19 in an uneven manner, with a greater volume of the supply air passing through a rear portion of the diffuser 19 adjacent a distal edge 47, than passes through a front portion adjacent a proximal edge 48. Consequently, this results in an excess of the supply air being delivered into the room along one side of the diffuser 19, thus reducing the efficiency of the difTuser and how it conditions the air of the room. In some instances it has been postulated that such an arrangement can result in the condition as shown in FIG. 2B. In this condition, due to the large volume of supply air exiting the diffuser 19 along the distal edge 47 having high exit velocities, a low pressure region is thereby created towards the proximal edge 48, causing turbulence within the diffuser 19. This in turn can generate instances where air actually flows into the diffuser adjacent the proximal edge 48 of the diffuser 19 as shown.

As discussed previously, in order to address the above-mentioned deficiencies, an internal perforated screen has been proposed to be employed within the body 41 of the plenum chamber 40, above the diffuser 19. Such a screen has an effect to restrict air flow through the distal edge region 47 of the diffuser such that the supply air is better distributed along the surface of the diffuser 19. However, it has been found that introducing such a perforated screen has the potential to increase noise associated with the plenum box as well as create a substantial back pressure within the system 20, generating inefficiencies and potentially requiring a greater capacity supply fan.

FIG. 3 shows a plenum chamber 18 in accordance with one embodiment of the present invention. The plenum chamber 18 is configured to provide more even distribution of air from the plenum chamber 18 such that it can more evenly pass through the diffuser 18 to be distributed evenly throughout the room 12.

In the embodiment as shown in FIG. 3, the general configuration of the plenum chamber 18 is substantially the same as that shown in prior art device of FIG. 2A. As such, the plenum chamber has a body 26 in the form of a box having four side walls 27, a roof 28 and an open floor that forms an outlet 29, to which is mounted a diffuser or grille 19 The plenum chamber 18 of the present invention is preferably moulded from a polymeric material, such as expanded polystyrene, although it may also be made from sheet metal by conventional methods. In a preferred embodiment, the plenum chamber 18 inherently incorporates its own insulating and flame retardant properties and reduces costs associated with constructing the plenum chamber and associated labour and materials costs in insulating the device.

An inlet 30 is formed in one of the side walls 27, and is connectable to a supply duct 17 of the HVAC system of Figure 1. The inlet 30 acts in the same manner as inlet 45 of the prior art device of FIGS. 2A and 2B, namely to receive the supply air under pressure from the supply fan 16 and to deliver the supply air into the body 26. As shown, upon entering the interior of the body 26 the supply air takes a substantially right-angled rum in order to exit the outlet 29, and pass through the diffuser 19 to be evenly distributed into the room.

To facilitate even distribution of the supply air out of the outlet 29 and through the diffuser 19, a flow disturbing element 32 is provided within the body 26. The flow disturbing element 32 is positioned within the body 26 such that it is located opposite the inlet 30 so as to extend across the inlet 30. In this position, as the supply air enters the body 26 through the inlet 30, it impinges upon the surface of the flow disturbing element 32. Due to the configuration of the flow disturbing element 32, such contact causes a disturbance in the air flow. e.g. by creating turbulence within the supply air present within the body 26. The creation of turbulence within the flow of supply air acts to prevent the supply air from exhibiting laminar flow along the inner walls of the body 26 and preferentially exiting the body 26 along a common edge, as discussed above in relation to FIGS. 2Λ and 2B. In this regard, the flow disturbing clement creates eddy currents within the supply air flow which facilitates mixing of the supply air within the body 26. This ensures that upon introduction of supply air into the chamber 18, the body 26 of the chamber 18 initially becomes pressurised by the supply air from the bottom of the chamber 18 upwards, prior to the mass delivery of the supply air from the outlet 29. Due to the positive pressure of the supply air entering the body 26 through the inlet 30 being greater than the internal pressure of the mixed air within the body 26 of the chamber 18, the mixed air within the body 26 is displaced through the outlet 29 and the diffuser 19. As such, the supply air is more evenly distributed throughout the room.

In the arrangement as shown in FlG. 3, the flow disturbing element 32 is formed in the wall 27 and the roof 28 of the body 26 during the moulding process. However, it will be appreciated that the flow disturbing element 32 may alternatively be in the form of a separate insert that is positioned within the body 26 following the moulding process.

As shown, the shape of the surface of the flow disturbing element 32 facilitates disturbance and particularly turbulent flow within the supply air and mixing/pressurisation of the supply air within the plenum chamber 18. In this regard, rather than the surface of the flow disturbing element 32 having a smooth concave arc, as is the case with the guide member 46 of FIGS 2A and 2B, the surface of the flow disturbing element 32 has a changing or irregular curvature consisting of at least one concave region in combination with at least one convex region.

In the specific embodiment as shown in FIO. 3, a first concave region 34 is provided on the surface of the flow disturbing element 32 and extends from the roof 28 of the box 26 to a distance X below the top of the inlet 30 where there is an inflexion point in the curvature.

A smaller convex region 35 is then provided on the surface of the flow disturbing clement which defines a ridge or peak which is located a distance Y above the bottom of the inlet 30. The distance Y is shown as less than half the height of the inlet, ensuring that the first concave region 34 leading to the ridge or peak of the convex region 35 encounters a greater proportion of the incoming air flow from the inlet 30. However, the optimal proportions and positioning of the regions 34, 35 in relation to the inlet 30 can be empirically determined to optimise the air flow characteristics. A second concave region 36 extends from the convex region 35 to the outlet 29.

As shown, each of the first concave region 34, convex region 35 and second concave region 36 are formed in a continuous manner along the surface of the flow disturbing element 32.

As will be appreciated, the first concave region 34 and the convex region 35 are facing in the direct path of the inlet 30 and hence contribute significantly to generating turbulent flow or eddies within the body 26 of the plenum chamber 18. Due to the first concave region 34 extending across a greater region of the supply air flow path, eddy currents 37 are induced within the supply air flow in this region, as shown. The eddy currents 37 create a turbulence within the plenum chamber 18 which facilitates mixing of the supply air and pressurisation of the internal space of the body 26, and prevents or inhibits the creation of laminar flow within the body 26. As the internal pressurised air within the body 26 is continually displaced by the higher pressure supply air entering the inlet 30. the mixed air within the body 26 is forced through the diffiiser 19 in an evenly distributed manner This enables the diffuser 19 to function as designed, to more evenly distribute the supply air into the room.

An alternative embodiment of a plenum chamber 40 of the present invention is shown in FIGS. 4A and 4B. The chamber 40 comprises a body 42 having an open end or bottom 44 and an inlet 43 formed in a wall thereof. The inlet 43 is shown as a cylindrical hole or spigot, which is correctable to a supply duct of a ITVAC system to receive supply air. under pressure. The body 42 is configured to define an internal space 41 into which supply air is received as it passes from the inlet and out the open end or bottom 44. As is shown more clearly in FIG. 4B. the space 41 is narrowei in cross section at or adjacent a roof of the body, and is widest at the open end or bottom 44.

A flow disturbing clement 45 is provided on an inner wall of the body 42, opposite the inlet 43 As discussed above, the flow disturbing element 45 is positioned within the supply air flow path such that supply air entering the space 41, through the inlet 43, is incident upon a surface 48 of the flow disturbing element 45. Due to the configuration of the flow disturbing element 45, as the flow of supply air impinges upon the surface 48. a turbulence or disturbance is created in the flow of the supply air. This disturbance results in mixing of the supply air within the space 41 prior to a majority of the air exiting the open end or bottom 44. As such, the space 41 of the chamber 40 essentially becomes pressurised by the supply air. Such a disturbance in the flow of supply air from the inlet 43 to the open end or bottom 44 also substantially prevents laminar flow of the supply air along the surface 48. Λs shown in FIG. 4B, the flow disturbing element 45 is configured such that the surface 48 is substantially flush with the internal wan of the body 42 at a first or upper end 45a. The surface 48 is then shaped to gradually project from the interna! wall of the body 42 into the space 41 as the surface 48 extends towards the open end or bottom 44, This results in the formation of a rounded projection or ridge 49 that extends across the surface 48 towards the open end or bottom 44. The region 46 of the surface 48 between the first or υppei end 45a and the apex of the ridge 49 has a substantially concave configuration.

As is shown, the inlet 43 is angularly disposed towards the open end or bottom 44 by an angle Θ. Angle Θ may vary between 5° - 25°, and is -preferably about 16°. In this arrangement, as the concave region 46 of the flow-disturbing element 45 extends substantially across the inlet 43. the majority of the supply air is directed in a downward direction into the concave region 46. This causes the majority of the supply air to contact the surface 48 and be deflected away from the flow-disturbing element 45 and back into the supply air path, rather than being directed directly towards the open end or bottom 44. As shown in FIG. 9, such air flow conditions generate eddy currents within the space 41 which acts to pressurise the space 4 J prior to air delivery.

The location of the apex of the ridge 49 with respect to the lowermost edge of the inlet 43 assists in controlling distribution of the supply air from the space 41 through the open end or bottom 44, As is shown in FTG. 4B. the ridge 49 has a substantially convex profile, with the apex of the ridge forming a division between the concave region 46 and a convex region 47 that is located downstream of the apex of the ridge 49. As shown in FIG. 4B, the apex of the ridge 49 is positioned a distance X above the lowermost edge of the inlet 43. This distance X can be represented as a proportion of the diameter D of the inlet 43 such thai X may be between 1-10%, and preferably 5% of the diameter D of the inlet. Such a configuration ensures that approximately 95% of the supply air is incident upon the concave portion 46 as it enters the space 41 to assist in pressurising the space 41.

As shown in FIG. 9, the remaining 5% of supply air is incident upon the convex region 47 of the flow disturbing element 45. This proportion of supply air is able to pass along the surface of the convex region 47 to be distributed out the distal region 50 of the open end or bottom 44. The distal region 50 of the open end or bottom 44 is that region of the open end or bottom 44 that is located beyond the flow disturbing element 45.

In the arrangement of this embodiment of the invention, as supply air is delivered into the space 41 by way of the inlet 43, approximately 95% of the supply air is incident upon the concave region 46 of the flow disturbing element 45. Instead of this supply air being directed out the open end or bottom 44, the supply air is deflected back into the space 41 such the space 41 becomes pressurised by the supply air. Following pressurisatton of the space 41 , as the supply aii is continuously delivered into the space 41 under a pressure that is greater than the pressure of the air within the space 41, a pressure differential is created. This pressure differential results in the pressurised air within the space 41 being displaced by the supply air out the open end or bottom 44 and through the diffuser or grille 52 attached thereto.

The embodiment described above in relation to FIGS. 4Λ and 4B shows the flow disturbing element 45 as being formed integral with the body 42 of the chamber 40. It will be appreciated that the flow disturbing element 45 and the body 42 of the chamber 40 may be formed separately, as shown in FIGS. 5 and 6, and attached together to form the chamber as shown in FIG. 7. For reasons of clarity, the same reference numerals will be used to refer to the same/similar features as described in relation to the integral arrangement discussed above. FIG. 5 shows one embodiment of a detachable flow-disturbing element 45. The first or upper end 45a of the flow disturbing element 45 includes a finger projection 53 and the second or lower end 45b of the flow disturbing clement 45 includes an arm 55. The finger 53 is shaped to be inserted into a recess 54 formed in the wall of the body 42 in the manner as shown in FIG. 8A. In this arrangement, the first or upper end 45a of the element 45 can be initially positioned such that it is flush with the inner surface of the wall of the body 42 (FIG. 7). Once the first or upper end 45a has been secured, the second or lower end 45b can be pressed in place such that the arm 55 is received over the surface of the body 42. Rib 56 of the arm 55 is then received in a recess 57 provided. along the surface of the body 42 (FIG. 8B). The flow disturbing clement 45 is then secured at either end 45a and 45b by way of an interference fit to the inner wall of the body 42.

The provision of a detachable flow disturbing element 45 enables the body 42, as shown in FIG. 6, to be formed such that multiple bodies 42 can be stacked together for transport to a site. Upon delivery to the site, the flow disturbing elements 45 can be attached to the body 42 prior to installation of the plenum chamber 40 into the HVAC system. Such an arrangement provides simple and easy delivery and installation of the chamber 40.

The plenum chamber 40 can be used with a variety of diffusers/grilles 52 in the manner as shown in FTG. 9. To achieve this, the open end or bottom 44 of the body 42 is provided with a number of stepped recesses 58 that enable fitting of a variety of commercially available diffusers/grillcs 52. Hence, the plenum chamber 40 can be used in association with a variety of diffusers/grilles 52. according to the air flow needs of the application, and various aesthetic requirements. In each of the embodiments described above, the body 42 of the plenum chamber 40 may be moulded from a suitable polymeric material, such as polystyrene. Alternative!}', the body 42 could also be made from a sheet metal having an insulating layer provided therein. It will be appreciated that the plenum chamber of the present invention provides a simple and effective means for distributing supply air from a supply duct to a diffuser or the like of a HVAC system for delivery of the supply air into a space. As the supply air is evenly distributed across the surface of the diffuser or the like, the diffuser is able to effectively deliver the air into the space in a uniform manner. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims

CLAIMS:

₁. A plenum chamber for use adjacent a diffuser or the like of a heating, ventilating oi air conditioning system, including: a body defining a space for receiving air supplied from a duct of the heating, s ventilating or air conditioning system; an inlet connectable to the duct for delivering the air into the space; an outlet through which air passes from said space to said diffuser; and a flow disturbing element located within said space such that air delivered into said space through the inlet impinges upon a surface of the flow disturbing element to l o disturb the flow of said air in said space to facilitate mixing and pressurisation of said air within the space as the air passes to the outlet.

2. A plenum chamber according to claim 1 , wherein the surface of the flow disturbing element has at least one concave region in combination with at least one convex region.

15 3. A plenum chamber according to claim 2, wherein the surface of the flow disturbing element is continuous such that the at least one concave region and the at least one convex region combine to form a continuous curved surface.

4. A plenum chamber according to claim 3, wherein the continuous curved surface comprises a first concave region and a second concave region connected by a convex

20 region.

5 A plenum chamber according to claim 4, wherein the first concave region is positioned to substantially face the inlet such that a majority of the air flow delivered by the inlet impinges upon the first concave region to disturb the air flow within the space to facilitate mixing of the air downstream of the convex region

6. A plenum chamber according to any one of the preceding claims, wherein the inlet is a tubular member configured to engage with the duct of the heating, ventilating or air conditioning system.

7. A plenum chamber according to any one of claims 1 to 5, wherein the inlet is a hole or spigot formed in a wall of the body.

8. A plenum chamber according to claim 6 or claim 7, wherein the inlet is configured to delivering the air into the space at an angle such that the air is directed towards the outlet.

9. A plenum chamber according to claim 8. wherein the inlet is disposed at an angle of between around 5° - 25° to the horizontal.

10. Λ plenum chamber according to any one of claims 1 to 5» wherein the flow disturbing clement is formed integral with the body.

1 1. A plenum chamber according to claim 10. wherein the flow disturbing element is an internal wall of the hody.

12. A plenum chamber according to any one of claims 1 to 5, wherein the flow disturbing element is formed separate to said body and is attachable to an inner wall of the body.

13. A plenum chamber according to claim 1. wherein the outlet is configured to receive a variety of different types of diffusers.

14. A method of handling air for delivery to a diffuser or the like of a heating, ventilating or air conditioning system comprising: receiving air from a supply duct into a space, said air being received at a supply pressure; collecting at least a portion of said air within the space such that the air within the space is pressurised to a level at or below said supply pressure; and delivering said air from said space and through an outlet under action of the supply pressure.

15. A method of handling air according to claim 14. wherein the step of collecting at least a portion of said air includes mixing said air within the space.

16. A method of handling air according to claim 15, wherein the air is mixed within said space by directing the air onto a flow disturbing element located within said space such that air received into said space impinges upon a surface of the flow disturbing element to disturb the flow of said air in said space to facilitate mixing and pτessurisation of said air within the space.

17. A method of handling air according to claim 15, wherein a pressure differential is created between the air supplied to the space and the air collected in the space, and this pressure differential causes the air to be delivered from the space and through the outlet.

18. A plenum chamber substantially as hereinbefore described with reference to the accompanying Figures.

19. A method of handling air substantially as hereinbefore described with reference to the accompanying Figures.