GB2527377A

GB2527377A - Improvements in ventilation ducts

Info

Publication number: GB2527377A
Application number: GB1413511.5A
Authority: GB
Inventors: Marius Cical
Original assignee: Individual
Current assignee: Individual
Priority date: 2014-05-28
Filing date: 2014-07-30
Publication date: 2015-12-23
Anticipated expiration: 2034-07-30
Also published as: GB201409465D0; GB201413511D0; GB2527377A8; GB2527377B8; GB2527377B

Abstract

A duct component 26 defines a flow path for a fluid, the duct component 26 comprising a portion 27 that is curved or angled so as to redirect a fluid entering the duct component 26 at a first angle to exit at a second angle. The duct component 26 defines a flow path plane comprising said first and second angles. The duct component 26 comprises a plurality of elongate diverting vanes 36 configured to assist and control the redirection of the fluid. The vanes 36 extend along at least a part of said flow path and the vanes 36 are oriented substantially perpendicularly to the flow path plane. The plurality of diverting vanes 36 neither coextend in the same direction as each other nor to walls of the duct component 26.

Description

Improvements in Ventilation Ducts

Technical Field

The present invention relates to a duct or duct fitting for a ventilation system.

Background to the Invention

Ventilation systems for buildings are required to ensure the health and safety of people in and around buildings, e.g. to avoid the presence of moist air, which would otherwise lead to a build-up of condensation and mould, in turn leading to structural damage to the building and/or an adverse effect on the health of the occupants.

Mechanical extract ventilation (MEV) systems provide continuous extraction of polluted or damp air from wet rooms', e.g. kitchen, bathroom, utility room etc., in a dwelling or building. Mechanical Ventilation with Heat Recovery (MVHR) units provide fresh air ventilation, for example into rooms of a building, and removal of warm damp air from said rooms.

Typically a ventilation unit is located in a roof space or utility room of a building, with fresh air inlet(s)/outlet(s) as required for the particular installation. A manifold may be connected to the ventilation unit, this providing a centralised distribution system for supplying air to a room or exhausting foul air from a room. The manifold typically comprises several distribution points allowing supply to/exhaust from a number of rooms in a building. Ducting connects the various components, inlets and outlets. A variety of duct fittings are used to join lengths of duct together, to connect it to one of the system components. Duct fittings are also useful when a change of direction is required e.g. to direct the fluid pathway towards its destination or to avoid an obstacle.

If a change of direction or an obstacle is present in ducting, however, this can have a detrimental effect on the flow properties of air flowing therethrough, e.g. by introducing turbulence.

It is known to provide internal guide elements within ducting in order to address this problem, e.g. as shown in EP 1,788,259. Here, curved parallel guide elements are provided that extend parallel to each other and to the internal walls of the duct fitting.

Aspects and embodiments of the present invention have been devised with the foregoing in mind, and aim to improve upon existing duct fittings used in/with ventilation units and systems.

Summary of the invention

According to a first aspect of the present invention there is provided a duct or duct component defining a flow path for a fluid such as air to be conveyed therethrough.

Preferably, the duct component comprises a portion that is curved or angled so as to redirect a fluid entering the duct component at a first angle or direction to exit at a second angle or direction. The duct or duct component thus defines a flow path plane containing the first and second angles or directions. A plurality of diverting vanes is preferably located within the flow path, configured to assist and control the redirection of the fluid. The vanes are preferably elongate and extend along at least a part of the flow path. The vanes are preferably oriented substantially perpendicular to the plane of the flow path. The diverting vanes are preferably neither parallel nor coextend in the same direction as each other or to the walls of the duct or duct component.

This arrangement advantageously provides a more uniform fluid flow across the duct or duct component, minimising speed and flow turbulences. The turning vanes split the fluid flow into smaller channels or streams within the larger duct, to help dissipate turbulent flows. In an embodiment, for a planar e.g. horizontal duct or duct fitting e.g. of substantially rectangular cross section, the flow path therethrough is planar (e.g. horizontal) and the diverting vanes extend substantially perpendicular thereto (e.g. vertically) so as to provide, at least in part, a series of flow path channels.

Preferably, each of the plurality of diverting vanes is curved, with each having a curvature that is different to that of the other diverting vanes and to that of the walls of the duct or duct component.

The duct or duct component may further comprise a first straight portion adjacent the curved portion on the inlet side thereof and/or a second straight portion adjacent the curved portion on the outlet side thereof In an embodiment, one or more of the diverting vanes extends from the curved portion into the second straight portion. One or more of the diverting vanes may originate at the border of the first straight portion and the inlet side of the curved portion.

The diverting vanes may be the same length, but are preferably of different lengths.

In an embodiment, the plurality of diverting vanes are positioned at different locations along the flow path within the duct or duct component, i.e. with some originating/being located more upstream than others.

Preferably, the duct or duct component comprises at least one primary diverting vane that extends across a majority of or the entire curved portion, and at least one secondary diverting vane which extends a much smaller distance across the curved portion. The primary diverting vane may also extend into the second straight portion without the secondary diverting vane extending into either the first or second straight portion.

More preferably, the duct or duct component comprises two primary diverting vanes that extend across a majority of or the entire curved portion, and two secondary diverting vanes that extend a much smaller distance across the curved portion.

The primary diverting vanes may be alternated with the secondary diverting vanes. In an embodiment, the primary diverting vanes are alternated with the secondary diverting vanes with one of the primary diverting vanes being located innermost with respect to the inner wall of the curved portion.

Such embodiments, and in particular those in which the vanes extend into the adjacent straight section, advantageously force the fluid to fill the section of the bend as the fluid exits the curved portion of the duct or duct connector.

For embodiments comprising two longer vanes and two shorter vanes, the former provides for improved performance whilst the latter prevents or reduces air rushing.

The diverting vanes may be affixed to or in the interior of the duct or duct component, or to a base plate, by welding, e.g. by sonic welding or solvent welding. Alternatively, the diverting vanes are affixed to or in the interior of the duct or duct component, or to a base plate, using a mechanical fixing means. In an embodiment, one or more of the diverting vanes are affixed to a base plate or to an interior surface of the duct or duct component. The base plate may compilse one or more male/female components that are configured to be received in a complementary female/male component provided in the duct or duct component. Each turning vane may comprise one or more male/female components that are configured to be received in a complementary female/male component provided in the duct or duct component or base plate. The male component may be a flange, clip, projection or suchlike, and the female component may be a slot, groove, channel, recess or suchlike.

The duct or duct component may be a discrete component or duct connector, or is integrally formed within a larger ducting section.

Embodiments of the invention will now be described with reference to the Figures of the accompanying drawings in which: Figure 1 shows a schematic view of a ventilation unit in a building; Figure 2 is an isometric view of a duct component comprising diverting vanes, for use in a ventilation system such as that of Figure 1; Figure 3 is an isometric view of the duct component of Figure 2 with the diverting vanes shown separately; Figure 4a is an isometric view of the duct component with the diverting vanes shown separately, according to an alternative embodiment; Figure 4b is an isometric view of the diverting vanes of Figure 4a in situ within the duct component, with the top part thereof removed; Figure 4c is an underneath view of the turning vanes assembly of Figure 4a; Figure 4d is an end on view of the duct connector of embodiments of the invention; Figure 5 is a schematic top/bottom cross sectional view of the duct component of Figure 2/Figures 4a-4d; Figures 6a to Of show computational fluid dynamics performance results for various configurations of known arrangements and embodiments of the present invention; and Figures 7a and 7b show computational fluid dynamics performance results for the configuration of an embodiment of the present invention under different flow conditions.

Detailed description of embodiments of the invention Figure 1 shows an exemplary building 10 and a ventilation system 12 installed therein.

The ventilation system 12 is conveniently located in a loft or roof space of the building 10, but could be located elsewhere if required. In this example a mechanical ventilation and heat recovery system (MVHR) is used comprising a central ventilation and heat recovery unit 14. Outlets/vents 16 to the exterior of the building 10 are provided, as are outlets/vents to other rooms 18 of the building 10. Polluted air is extracted from rooms within the building using known means, e.g. adjustable extract air valves or fixed grilles 20. Fresh air may be fed into the rooms via the inlets 18.

Ducting 22 is used to provide a fluid passageway for the fresh and foul air as required and to make connections between the various components. It will be appreciated that embodiments of the invention can conveniently and advantageously be incorporated in ventilation systems, and particularly domestic ventilation systems, but they may also be utilized in many other applications incorporating a fluid flow system.

The duct network comprises sections 24 in which a change of direction is required, or in which there is a junction for connection with further ductwork. Figures 2 to 4 show an exemplary duct portion or component 26 that provides for such a change in direction of the flow path.

Figure 2 shows a duct portion or component 26 in the form of a duct fitting. The example shown is a horizontal duct fitting 26 with a rectangular inlet 28 that is substantially identical to a rectangular outlet 30. The duct fitting 26 comprises a major curved portion 27. The fitting 26 is hollow and tubular and forms a bend of substantially 90° between the inlet 28 and outlet 30. The inlet 28 and outlet 30 are rectilinear, and quadrate in the example shown. An inlet connector 32 and an outlet connector 34 enable the fitting 26 to be connected to further ductwork (not shown). A plurality of turning or diverting vanes 36 is provided within the internal cavity defined by the duct fitting 26.

This duct fitting 26 is particularly suitable for connecting two lengths of ducting of rectangular cross section, but in other embodiments of the invention the cross section of the duct fitting 26 may be a different shape. The inlet 28 and/or outlet 30 may also be different in size and shape. The bend also need not be 900 -other angles are envisaged having a sharper or shallower bend.

Figure 3 shows the duct fitting 26 of Figure 2, but with the turning vanes 36 shown separately, e.g. prior to installation in the fitting 26. In the embodiment shown, four turning vanes 38, 40, 42, 44 are utilised. The turning vanes 36 are rigid sheet elements that are curved or comprise a curved portion. To facilitate fixing of the turning vanes 36 in the duct fitting 26, each may be provided with a base portion 46 provided orthogonally to the curved wall element. The base portions of the turning vanes 36 may be attached to the base or other internal surface of the duct fitting 26 by sonic welding or solvent welding, or any other suitable means. In the embodiment shown, the turning vanes 36 themselves extend substantially perpendicularly to the plane of the duct fitting 26 (which is also the plane of the flow path). The bases, if incorporated, will extend in the same plane as the major surfaces of the duct fitting 26.

Figures 4a to 4d show an alternative embodiment, wherein one or more mechanical fasteners are used to secure the turning vanes 36 to the base 46 or other internal surface of the duct fitting 26, instead of welding. In the embodiment shown, each turning vane 36 is mounted on a common base 46. The base 46 is conveniently a sheet element in the shape of a quadrant (quarter circle). Preferably the base 46 is of a similar shape to the duct bend 26, but with some clearance around the edge(s) thereof to facilitate insertion therein. A projection, flange, hook or clip 47 is provided along one or each straight edge of the base 46. The clip 47 projects outwardly and/or away from the base 46. I.e. in the orientation shown in the figures, the clip 47 projects outwardly and downwardly at an angle away from the base 46. The angle may, for example, be substantially 90°, but other angles may also be used e.g. in the range 80° to 100° and e.g. substantially integer values therebetween. The clip 47 may also be formed with a draft angle e.g. of substantially 3° (or perhaps 2.5°, 2°, or as required), for manufacturing purposes. In the embodiment shown, the clip 47 is an elongate strip attached to or integrally formed with the base 46. The duct fitting 26 comprises correspondingly shaped slot(s) or recess(es) (not shown) for receiving the clips 47.

The duct fitting 26 allows for elastic deformation and, as such, the turning vanes assembly 36, 46 can be urged inside, deflecting the duct fitting 26 as indicated by the arrows in Figure 4d, until in their final position defined by the clip 47 and slots. The turning vanes assembly 36, 46 can be secured in place by urging the clips 47 into corresponding slots/channels provided in the base of the duct fitting 26, as indicated by the arrows in figure 4b. The turning vanes assembly 36, 46 can be inserted into the duct housing 26 from either side, i.e. through the inlet 28 (as shown by the arrow in Figure 4a) or the outlet 30. The clips 47 advantageously help locate and lock the vanes 36 in position inside the duct fitting 26. Similar fixing features (not shown) could be provided for securing each turning vane 36 in the base 46, or these may be attached to the base by a welding method as discussed above. The internal corner 49 of the base 46 is notched or cut-away to facilitate location and fixing with respect to the internal corner of the duct fitting 26.

The relative arrangement of turning vanes 36 in figures 2 and 3 is the same as that shown in Figures 4a to 4d -the latter is simply shown in the mirror image compared with the former. As such, both provide the same performance and flow characteristics.

Figure 5 shows the positioning and configuration of the diverting vanes 36 within the duct fitting 26. The large arrows indicate the direction of fluid flow into and out of the duct fitting 26. The external angle a of the duct fitting 26 is substantially 90° and the internal angle 2 is also substantially 900. The duct fitting 26 shown therefore imparts a directional change of 900 to fluid flowing therethrough. It will, however, be appreciated that the duct fitting 26 could be configured differently to have an external and/or an internal angle that is not substantially 900. It is also not necessary, in some embodiments, for the internal and external angles to be the same.

In the embodiment shown, the diverting vanes 36 are neither parallel nor co-extend to each other, nor to the upright/transverse walls of the duct component 26.

Conveniently, each of the diverting vanes 36 are elongate and curved, with each having a curvature that is different to that of the other diverting vanes 36 and to that of the walls of the duct component 26 (as is apparent from the tangents to each included on Figure 5). All of the turning vanes 36, however, extend in the same plane and perpendicular to the flow path and the plane of the duct fitting 26. In the embodiment shown, the vanes 36 extend substantially perpendicularly to horizontal base i.e. they extend substantially vertically. This provides for simple manufacturing processes.

For the embodiment shown, two of the diverting vanes 38, 42 originate at the border of the inlet 32 connector and the inlet side of the curved portion of the duct fitting 26.

These vanes 38, 42 also extend beyond the border of the outlet side of the curved portion of the duct fitting 26 and the outlet connector 34. The respective portions thereof 46, 48 are straight or have only a slight curvature. The terminal end of the innermost vane 38 extends beyond the limit of the outlet connector 34, and will thus extend into ducting when connected thereto. Diverting vanes 40, 44 are shorter.

Diverting vane 40 is located at, adjacent or in the vicinity of the outlet 30. It originates within the curved portion of the duct fitting 26 and terminates beyond the border with the outlet connector 34. The terminal end thereof is straight or only slightly curved.

The diverting vane 44 is located approximately midway along the extent of the duct fitting 26, such that neither end thereof extends past the border with the inlet 32 or outlet 34. Notably, the two shorter vanes 40, 44 are interposed between the two longer vanes 38, 42. In an embodiment, therefore, one or more secondary or short vanes 36 are utilised in combination with one or more primary or long vanes. The secondary vane(s) may be located entirely within the curved portion of the duct fitting without extending into or beyond the inlet 28 or the outlet 30, or may be located at or near the inlet/outlet 28, 30 and may extend into the inlet/outlet 28, 30. In an embodiment, one or more vanes may extend beyond the inlet/outlet 28, 30 and into adjacent ducting, when present. In embodiments, the primary vanes in particular may comprise a curved portion and a straight portion with the straight portions extending into the inlet/outlet 28, to assist in flow redirection. In a preferred embodiment, primary vanes 38, 42 are alternated with secondary vanes 40, 44, most preferably with a primary vane 38 located innermost in the curved duct fitting 26.

Although the arrangement of four vanes 36 (two primary vanes alternated with two secondary vanes) has been found to be beneficial, as will be discussed below, alternative arrangements of turning vanes 36 may be employed in other embodiments (not shown). For example, fewer or more vanes 36 may be provided, e.g. two, three, five, six, seven, etc. Providing curved vanes 36, or vanes with a curved portion, is beneficial to assist in smoothly diverting fluid passing thereby without introducing turbulence, but the degree of curvature thereof may be increased or decreased as required. The vanes 36 may be the same length or of a different length to one or more of the other vanes 36. The vanes 36 may be located at the same or different positions along the flow path within the duct fitting 26. The vanes 36 may originate and/or terminate at the same or different positions along the fluid flow path. In the embodiment shown, the vanes 36 are substantially equally spaced in the radial direction, normal to the flow path direction, but pairs of vanes 36 could be located closer together or further apart dependent upon the fluid flow characteristics required.

The vanes 36 may or may not be distributed evenly across the radial extent of the curved duct fitting 26.

Figures 2 to 5 show a duct component 26 as a discrete component connectable to other ducting via the inlet connector 32 and the outlet connector 34. The term "duct component" is considered to also cover a part of a larger ducting section. I.e. a longer duct component 26 could be manufactured to incorporate a bend or curve with the vanes 36 affixed to or integrally formed with the interior thereof Thereby, one or more vanes 36 may extend beyond the curved or bent portion 27 of the duct component 26 and into a straight portion or another curved portion.

Figures 6a to 6f show results obtained from a computational fluid dynamics (CFD) analysis, which demonstrates the advantages and improved performance achieved by embodiments of the invention compared with known arrangements of turning vanes and without any turning vanes. The tests were performed on a duct component comprising a horizontal 90° bend of size 204mm x 60 mm. The following parameters were considered to be constant throughout the test: airflow 30 Ifs, temperature 20°C, with atmospheric pressure at discharge.

Figure 6a demonstrates the behaviour of a flow of air within the 90° bend without any turning vanes. The air rushing noise generated inside ventilation ducting is strongly related to the speed of the air. The aim is to have a uniform flow across the section of the duct therefore keeping the speed and flow turbulences to a minimum. In Figure 6a it can clearly be seen that, as air encounters the bend, the air flow becomes turbulent denoted by region Ta within and after the bend.

It is known to provide turning vanes within the flow path to try to force the air into more uniform streams. The conventional approach, typically adopted in commercial/non-domestic duct systems is to have a specific number of turning vanes that are parallel to the walls of the bend and to each other. Figure 6b shows the effect of adding a single turning vane 36 parallel to the curve of the duct. Noticeably, the length over which the air is turbulent Tb is reduced but there is still a significant volume within which the air flow is turbulent.

In Figure 6c, two turning vanes 36, parallel to each other and to the interior walls of the duct fitting 26 are provided, and again the improvement in the amount of turbulence T can be seen.

In an embodiment of the invention, and as shown in Figure 6d, the curvature of the two turning vanes 36 is increased to provide the turning vanes with a sharper bend compared with the curvature of the wall of the duct fitting. It can clearly be seen that this forces the air into the section of ducting following the bend as the air exits the bend, thus further reducing the region of turbulence Td.

In another embodiment, and as shown in Figure 6e, the two turning vanes 36 each protrude beyond the curved duct fitting 26 and into the straight duct section. The region of turbulence Te is further reduced.

In Figure 6f, results using the configuration of Figures 2-5 is shown, i.e. incorporating two turning vanes 38, 42 for higher performance together with two shorter vanes 40, 44 to mitigate against or prevent air from rushing. The region of turbulence here T extends only a small distance beyond the termination of the curved portion 26.

The use of turning or diverting vanes 26 into duct components and fittings thus advantageously reduces the resistance to airflow, thereby greatly improving system performance and reducing the energy required to move the fluid flowing therethrough.

The size and positioning of the diverting vanes, including the protrusion of the diverting vane(s) into the socket of the fitting/adjacent straight section, beneficially evens out the distribution of the fluid at the exit of the curved portion.

It can clearly be seen from Figures 6a to 6f that, based on in-house testing, the use of non-parallel vanes provides an improved performance to using parallel vanes, whilst providing greater flexibility for the arrangements that can be constructed and ease of manufacture.

Furthermore, embodiments of the invention are able to cope with increased flow rates without any negative effect on performance. Figure 7a shows flow results again using the configuration of Figures 2-5, i.e. incorporating two turning vanes 38, 42 for higher performance together with two shorter vanes 40, 44 to mitigate or prevent air from rushing. In Figure 7a the CFD is performed with an airflow of 30 I/s and in Figure 7b the CFD is performed with an airflow of 60 Its, i.e. double. In both Figures 7a and 7b, the region of turbulence here T extends only a small distance beyond the termination of the curved portion 26. Thus, although the flow speed changes dramatically, advantageously the air pattern is substantially unchanged. The system shown can thus beneficially be utilised for a wide range of airflow speeds without any detrimental effect on performance.

Claims

CLAIMS: 1. A duct component defining a flow path for a fluid to be conveyed therethrough, the duct component comprising a portion that is curved or angled so as to redirect a fluid entering the duct component at a first angle to exit at a second angle, the duct component defining a flow path plane comprising said first and second angles, and a plurality of elongate diverting vanes configured to assist and control the redirection of the fluid, the vanes extending along at least a part of said flow path, the vanes being oriented substantially perpendicularly to the flow path plane and wherein the plurality of diverting vanes neither coextend in the same direction as each other nor to walls of the duct component.
2. The duct component of claim 1, wherein each of the plurality of diverting vanes are curved, with each having a curvature that is different to that of the other diverting vanes and to that of the walls of the duct component.
3. The duct component of claim 1 or claim 2, wherein the duct component further comprises a first straight portion adjacent the curved portion on the inlet side thereof and/or a second straight portion adjacent the curved portion on the outlet side thereof.
4. The duct component of claim 3, wherein one or more of the diverting vanes extends from the curved portion into the second straight portion.
5. The duct component of claim 3 or 4, wherein one or more of the diverting vanes originates at the border of the first straight portion and the inlet side of the curved portion.
6. The duct component of any preceding claim, wherein the plurality of diverting vanes are of different lengths.
7. The duct component of any preceding claim, wherein the plurality of diverting vanes are positioned at different locations along the flow path therewithin.
8. The duct component of any preceding claim comprising at least one primary diverting vane that extends across a majority of or the entire curved portion, and at least one secondary diverting vane which extends a much smaller distance across the curved portion.
9. The duct component of claim 8, wherein the primary diverting vane also extends into the second straight portion and the secondary diverting vane does not extend into either the first or second straight portion.
10. The duct component of claim 8 or 9 comprising two primary diverting vanes that extend across a majority of or the entire curved portion, and two secondary diverting vanes that extend a much smaller distance across the curved portion.
11. The duct component of claim 10, wherein the primary diverting vanes are alternated with the secondary diverting vanes.
12. The duct component of claim 11, wherein the primary diverting vanes are alternated with the secondary diverting vanes, with one of the primary diverting vanes being located innermost with respect to the inner wall of the curved portion.
13. The duct component of any preceding claim, wherein the diverting vanes are affixed to the interior of the duct component by welding.
14. The duct component of any preceding claim, wherein the diverting vanes are affixed to or in the interior of the duct component by sonic welding or solvent welding.
15. The duct component of any of claims ito 13, wherein the diverting vanes are affixed to or in the interior of the duct component using a mechanical fixing means.
16. The duct component of claim 15, wherein one or more of said diverting vanes are affixed to a base plate or to an interior surface of the duct connector.
17. The duct component of claim 16, wherein the base plate comprises one or more male/female components that are configured to be received in a complementary female/male component provided in said duct component.
18. The duct component of claim 16 or 17, wherein each turning vane comprises one or more male/female components that are configured to be received in a complementary female/male component provided in said duct component or base plate.
19. The duct component of claim 17 or 18, wherein said male component is a flange, clip, projection or suchlike, and said female component is a slot, groove, channel, recess or suchlike.
20. The duct component of any preceding claim, wherein the duct component is a discrete component or duct connector or is integrally formed within a larger ducting section.
21. A duct component substantially as hereinbefore described with respect to Figures 2 to 5 of the accompanying drawings.