EP2816294A2

EP2816294A2 - Grill arrangement

Info

Publication number: EP2816294A2
Application number: EP14172105.0A
Authority: EP
Inventors: Zsolt Bako-Biro
Original assignee: VKR Holding AS
Current assignee: VKR Holding AS
Priority date: 2013-06-18
Filing date: 2014-06-12
Publication date: 2014-12-24
Also published as: GB2511148B; GB2511148A; EP2816294A3; GB201310814D0

Abstract

A grill arrangement 10 suitable for use in a natural ventilation system. The arrangement includes a plurality of curved vanes 14 which cause air to be accelerated therethrough. The vanes 14 are shaped such that accelerated air is turned towards a direction extending parallel to a ceiling or wall surrounding the arrangement 10. By virtue of a Coanda effect, this causes the air to attach to these surfaces and spread further into a room or other space.

Description

This arrangement concerns a grill arrangement for a natural ventilation system.
With natural ventilation which may be wind driven, and may be hybrid and include for instance an optional powered system, a generally much lower pressure potential is available than in mechanical air supply systems. Accordingly in a grill arrangement it is important not to encounter a significant loss of pressure. Therefore generally in such applications a very simple grill is used. Such grills may often result in low ventilation efficiency and inadequate comfort due to cold air reaching a living space or other directly from a ventilation outlet.
According to the present invention there is provided a grill arrangement for a natural ventilation system, the arrangement include a support structure locatable in an opening in a surface, and a plurality of spaced vanes mounted to the support structure, which vanes are curved to urge a flow of air entering the grill arrangement from outside of the surface to be turned towards a direction extending parallel to the surface.
The grill arrangement may be configured such that air passing through the grill arrangement from outside of the surface will substantially follow the profile of the surface by virtue of the Coanda effect.
The vanes may be curved from a direction perpendicular to the surface through an angle of between 80 and 65°, and in particular between 80 and 70°.
The vanes may include an arcuate part, and the spacing between the arcuate parts on adjacent vanes may correspond at least generally to the radius of the arcuate parts.
The vanes may also include a substantially tangential part at the downstream end of the arcuate parts. The arcuate parts may extend from four up to fifteen times the length of the tangential part.
The tangential parts may be configured such that the space between adjacent vanes reduces at the tangential parts, and the space may reduce by an amount less than 40%.
The radius of the arcuate parts of the vanes is typically kept unchanged across the arrangement.
The spacing between vanes at an upstream end thereof may be between 100 and 35mm, and particularly between 75 and 40mm. The spacing between vanes may be constant at least for the arcuate parts thereof.
The vanes may be configured such that there is substantially no line of sight through the arrangement.
The vanes may be located further in a downstream direction at a first part of the arrangement relative to a second part of the arrangement. A line extending between downstream ends of the vanes in the first part of the arrangement to the second part of the arrangement may be inclined at an angle to the horizontal of between 5 and 15°, particularly 8 and 12°, and more particularly at an angle of substantially 10°.
The first part of the arrangement may be towards the middle of the arrangement.
The arrangement may also include a central section, which in one embodiment includes a section which provides direct substantially straight ventilation therethrough. In a further embodiment the central section is closed, and may include an upstream pointing projection to direct air around the central section, which projection may be in the form of a four sided pyramid.
In a first configuration the arrangement includes one set of vanes extending from one side which constitutes the first part, to an opposite side which constitutes the second part.
In a second configuration two sets of vanes are provided each extending from opposite sides of an apex, which apex constitutes the first part.
In a third embodiment four sets of vanes are provided each extending to a respective side from an at least generally central first part.
The invention further provides a natural ventilation arrangement, the arrangement including a grill arrangement according to any of the preceding fifteen paragraphs
Embodiments of the present invention will now be described by way of example only and with reference to the accompanying drawings, in which:-

Fig. 1 is a diagrammatic view from beneath of a first grill arrangement according to the invention;
Fig. 2 is a cross sectional view of the arrangement of Fig. 1;
Figs. 3 and 4 are similar views respectively to Figs. 1 and 2 but of a second grill arrangement according to the invention;
Figs. 5 and 6 are similar views to Figs. 1 and 2 but of a third grill arrangement according to the invention;
Fig. 7 is a diagrammatic cross sectional view of a natural ventilation arrangement incorporating a fourth grill arrangement according to the present invention;
Fig. 8 is a diagrammatic cross sectional view through a lower part of the apparatus of Fig. 7 but incorporating a different grill arrangement;
Fig. 9 is a similar view to Fig. 8, and is a diagrammatic view showing operation of the third grill arrangement in use according to the invention;
Fig. 10 is a cross sectional detailed view through part of a grill arrangement according to the invention;
Fig. 11 is a diagrammatic view showing operation of part of a grill arrangement according to the invention;
Fig. 12 is a diagrammatic view from beneath of a fifth grill arrangement according to the invention; and
Fig. 13 is a diagrammatic cross sectional view through part of the grill arrangement of Fig. 12.

Figs. 1 and 2 show a first grill arrangement 10 suitable for use in a natural ventilation system. The arrangement 10 is square in plan view and comprises four sections 12 each comprising six vanes 14 as shown in Fig. 2. The vanes 14 curve outwardly and have a first arcuate portion 16 and an outer tangential portion 18. The vanes 14 are located sequentially downwardly towards the centre 20 of the arrangement 10.
The vanes 14 in the arcuate portion 16 are equispaced from each other and for instance have a spacing of 50mm. The gap between the vanes reduces in size with the tangential portions 18, causing air to be accelerated therethrough. The angle of a line connecting the top of the arcuate portions relative to the horizontal is 10°.
In practice air will flow downwardly through the arrangement 10 and outwardly as shown by the arrows 21 and illustrated for instance in Fig. 11. Positive pressure on the vanes is indicated by a plus symbol, and negative pressure along the air jet is indicated by a minus symbol. The air passes between the vanes 14 and is accelerated out thereof by virtue of the reduced spacing between the tangential portions 18. By virtue of the shape of the vanes the air jet is turned towards a direction extending parallel to a ceiling or wall surrounding the arrangement 10 and by virtue of a Coanda effect. This will tend to attach to these surfaces and spread further into the space. Air from the space below the arrangement 10 is dragged in to the supplied air due to the pressure conditions formed along the moving jet.
Figs. 3 and 4 show a second grill arrangement 22 which is similar to the arrangement 10 but only includes two sections 24 which are divided by a central apex 26. Each of the sections 24 again includes vanes 14 potentially producing an air flow in two directions as shown by the arrows 28.
Figs. 5 and 6 show a third grill arrangement 30 with just a single section with twelve vanes 32. As can be seen from Fig. 6 the vanes are curved to the left as shown, and also are mounted on a line inclined upwardly at 10° to the horizontal tos at the left hand side. This causes air to flow in a single direction as shown by the arrows 34.
Fig. 7 shows a natural ventilation arrangement 36 incorporating a fourth grill arrangement 38. The natural ventilation arrangement 36 is mounted on the roof of a building with a hollow cylindrical or square section body 42 which extends through the roof 40, and has a plurality of adjustable paddles 44 at a lower end thereof immediately above the grill arrangement 38 to adjust air flow therethrough.
A cruciform divider 46 is provided within the body 40, and a plurality of louvres 48 are provided in an upper part of the body 40 to permit air to pass into or out of the body 42. By virtue of the wind direction air will pass into one or two of the portions formed by the cruciform 46 within the body 40 as shown by the arrow 50. Air will be caused to exit from the opposite one or two portions formed by the cruciform 46 within the body 40, as shown by the arrow 52.
Air passing downwardly through the ventilation arrangement 36 and hence grill arrangement 38 will tend to follow the underside of the roof 40 by virtue of the Coanda effect as described above. An upwardly extending projection 54 is provided at the centre of the grill arrangement 38 to separate air passing into the building from air passing out thereof. Fig. 8 illustrates the passage of air into and out of a similar grill arrangement 56, but has a smaller number of vanes 58.
Fig. 9 illustrates air flow through the third grill arrangement 30 which just has a single section of vanes 32. As can be seen air entering through a gap in a wall 60 is turned to the left so as to tend to follow the underside of the wall 60 by virtue of the coanda effect.
Fig. 10 shows in more detail four vanes 62 in a grill arrangement according to the arrangement. Each of the vanes has an arcuate section 64 which has a radius approximately equal to the spacing between adjacent vanes 62. Each of the vanes 62 also has a tangential section 66 at their downstream ends, such that the spacing between the vanes 62 at their lower ends decreases causing accelleration of air passing therethrough.
The vanes 62 are sequentially spaced downwardly towards a first part which may be a central part of a grill arrangement such as shown in the grill arrangements 10 and 22. Lines illustrate the angle 68 by which the vanes 62 are spaced upwardly from the first part. In the example shown in Fig. 10 the spacing between the vanes 62 is 50mm and hence the radius of the arcuate part 64 is also 50mm. The angle 68 is 10°.
Figs. 12 and 13 shows a fifth grill arrangement 70 which could be suitable for instance with a natural ventilator which has a hybrid arrangement, including for example a central fan which may be solar operated, and operable as required, and particularly where there is not sufficient wind to produce natural ventilation.
The fifth grill arrangement 70 is generally similar to the first grill arrangement 10 except that a central section 72 is provided without any vanes, which permits direct vertical ventilation and will connect to for instance the solar powered fan. Illustrated by broken lines are modular extensions 74 on all four sides of the grill arrangement 70, for use in a location where a larger grill arrangement is required.
There are thus described a number of arrangements which by using the Coanda effect permit ventilation air to move essentially across a ceiling rather than directly down into a room. This helps to enhance ventilation efficiency by generally achieving a greater distance travelled for the ventilated air. This thus means that the same size of natural ventilation arrangement can be used for a larger room than would otherwise be the case with a conventional grill arrangement.
In conventional arrangements air will tend to bounce of the floor tending to mean that dirt will be picked up. In contrast, with grill arrangements according to the invention air will be delivered through a cleaner route to an occupied zone, rather than being bounced off a potentially dirty floor. In winter thermal jets may be cooler than the ambient temperature, and this arrangement will provide a longer time for thermal jets to be heated up by their surroundings.
With the arrangements described above there is essentially no line of sight which is aesthetically more pleasing and will tend to reduce noise penetration from roof level. As indicated modular arrangements may be possible, and a required number of vanes may be provided in different situations.
It is to be realised that various other modifications may be made without departing from the scope of the invention. For instance the vanes may have a different profile, and a different number or spacing of vanes may be used. The angle of the vanes relative to a horizontal alignment can be varied. Different configurations and vanes and/or other grill parts can be provided. The grill arrangement may have a number of different shapes such as square, rectangular or circular, with correspondingly shaped vane configurations.
Whilst endeavouring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.

Claims

A grill arrangement for a natural ventilation system, the arrangement include a support structure locatable in an opening in a surface, and a plurality of spaced vanes mounted to the support structure, which vanes are curved to urge a flow of air entering the grill arrangement from outside of the surface to be turned towards a direction extending parallel to the surface.
A grill arrangement according to claim 1, in which the grill arrangement is configured such that air passing through the grill arrangement from outside of the surface will substantially follow the profile of the surface by virtue of the Coanda effect.
A grill arrangement according to claims 1 or 2, in which the vanes may be curved from a direction perpendicular to the surface through an angle of between 80 and 65°, and more particularly between 80 and 70°.
A grill arrangement according to any of the preceding claims, in which the vanes include an arcuate part, and the spacing between the arcuate parts on adjacent vanes may correspond at least generally to the radius of the arcuate parts.
A grill arrangement according to claim 4, in which the vanes also include a substantially tangential part at the downstream end of the arcuate parts, the arcuate parts may extend from four up to fifteen times the length of the tangential part, the tangential parts may be configured such that the space between adjacent vanes reduces at the tangential parts, and the tangential parts may be configured such that the space between adjacent vanes reduces by an amount less than 40%.
A grill arrangement according to claims 4 or 5, in which the radius of the arcuate parts of the vanes is kept unchanged across the arrangement.
A grill arrangement according to any of the preceding claims, in which the spacing between vanes at an upstream end thereof is between 100 and 35mm, and more particularly between 75 and 40mm.
A grill arrangement according to claim 4, or any of claims 5 to 7 when dependent on claim 4, in which the spacing between vanes is constant at least for the arcuate parts thereof.
A grill arrangement according to any of the preceding claims, in which the vanes are configured such that there is substantially no line of sight through the arrangement.
A grill arrangement according to any of the preceding claims, in which the vanes are located further in a downstream direction at a first part of the arrangement relative to a second part of the arrangement, and a line extending between downstream ends of the vanes in the first part of the arrangement to the second part of the arrangement is inclined at an angle to the horizontal of between 5 and 15°, more particularly between 8 and 12°, may be substantially 10°, and the first part of the arrangement may be towards the middle of the arrangement.
A grill arrangement according to any of the preceding claims, in which the arrangement also includes a central section, which provides direct substantially straight ventilation therethrough.
A grill arrangement according to any of claims 1 to 10, in which the arrangement also includes a central section, which central section is closed, and the central section may include an upstream pointing projection to direct air around the central section, and the upstream pointing projection may be in the form of a four sided pyramid.
A grill arrangement according to claim 10, or claims 11 or 12 when dependent on claim 10, in which the arrangement includes one set of vanes extending from one side which constitutes the first part, to an opposite side which constitutes the second part.
A grill arrangement according to claim 10, or claims 11 or 12 when dependent on claim 10, in which two sets of vanes are provided each extending from opposite sides of an apex, which apex constitutes the first part.
A grill arrangement according to claim 10, or claims 11 or 12 when dependent on claim 10, in which four sets of vanes are provided each extending to a respective side from an at least generally central first part.