EP2417401B1

EP2417401B1 - Air supply device

Info

Publication number: EP2417401B1
Application number: EP10761930.6A
Authority: EP
Inventors: Bengt Sellö; Martin SELLÖ
Original assignee: Inventiair AB
Current assignee: Inventiair AB
Priority date: 2009-04-06
Filing date: 2010-03-18
Publication date: 2014-12-10
Anticipated expiration: 2030-03-18
Also published as: EP2417401A4; SE533713C2; WO2010117319A1; SE0900459A1; EP2417401A1; ES2531559T3

Description

Field of the Invention

The present invention relates to an air supply device for supplying fresh air into a room to be ventilated. It comprises a ventilation grid unit being arranged substantially flush with the surface of a wall or a floor in the room. The ventilation grid unit is provided with a set of air guiding profile elements oriented in parallel to each other and having a curved cross-sectional profile, so as to guide a supply air stream into a direction having a component in parallel to the wall or floor structure.

Background of the Invention and prior art

Such devices are previously known, e.g. from the German Utility Model DE 20219225 Ul , where the air guiding profile elements are constituted by straight blades being slightly inclined (figure 2), and from the International Patent Application published under No. WO2004/113103 A2 . In the latter device, the aim is to achieve a circulating air flow, where the air stream, upon being blown obliquely upwards from the ventilation grid in the floor of a room, turns backwards into a horizontal flow and then down again into the ventilation device through an inlet orifice, which is located at a distance from the air supply grid. Accordingly, air is circulated upwards, horizontally and downwards (figure 1). The inclinational angle of the guiding profile elements serves to widen the air circulation in the room, so that the air flow will not be short circuited from the outlet to the inlet of the device.
It is also generally known, from other documents, such as the published International Patent Application WO2005/114059 A2 , that relatively cool air may be supplied at low velocity near the floor of a room so as to achieve a so called displacement ventilation, where a low velocity air stream near the floor will displace relatively warm air in the room and bring about an orderly air flow upwards into an upper part of the room, where the relatively warm and possibly polluted air is drawn out through outlet openings near the ceiling.
A disadvantage with such "displacement" ventilation, with a low velocity air stream, is that it is necessary to provide very large supply air devices for feeding the necessary air flow at low velocity into the room. Although the air stream has a low velocity, it occupies a rather high layer, typically up to 1 m, above the floor. Accordingly, it is perceived as draughty and possibly also cold to any person in the room.

Object of the Invention

Against this background, the present invention aims at achieving an effective, comfortable ventilation in a room by means of an air supply device having moderate dimensions and being suitable for mounting at the floor or a wall, and yet providing an efficient ventilation which is comfortable to human beings.

Summary of the Invention

The main object stated above will be achieved by an air supply device having air guiding profile elements which are curved to a tangential angle at each outlet end being less than 15° relative to the floor or wall surface, so that the air stream flowing out from the ventilation grid unit is deflected into a substantially horizontal or vertical air flow forming a steady flow layer at a distance of at least 20 mm and no more than 100 mm from the floor or wall surface, wherein the flow velocity of the upwardly flowing air stream, at the outlet end of the ventilation grid unit, is at least 2.5 m/s, so that the resulting horizontal air stream will propagate along the wall and/or the floor with a high momentum. In this way, the supplied fresh air will propagate in a rather narrow layer along the wall and/or the floor, and this layer will reach regions of the room being situated at a relatively large distance from the air supply device. This is true even if the air stream hits a wall, a floor or some other object, where the air stream bounces back or is deflected so as to follow an adjacent wall or floor surface, because of the high momentum of the air stream.
Furthermore, according to a further advantageous feature of the present invention, each air guiding profile element comprises a step-like irregularity along its length, forming a step in the direction of the outflowing air stream. Such a step may be formed on either one of the two sides of the profile element, i.e. on the concave side and/or on the convex side thereof. In a preferred embodiment, there is such a step on both sides.
In order to further enhance a uniform air flow at the outlet ends of the air guiding profile elements, the outlet ends of these profile elements may be tapered into a longitudinally extending edge. Such an edge may be cut off, so as to form an edge surface, or else may these outlet ends be smoothly rounded.
At the external and internal sides of the longitudinally extending edge, the tangential direction may be less than 10° relative to the floor or wall surface, possibly less than 5° at the external side and less than 10° at the internal side, and possibly also substantially parallel to the floor surface (which is normally horizontal) or the wall surface (which is normally vertical).
As indicated above, the steady flow layer formed at the downstream side of the air supply device, may be even more narrow, e.g. in an interval between 30 mm and 90 mm above the floor.
It is possible to mount the air supply device at the floor relatively close to a wall of the room, and to direct the outflowing air from the ventilation grid away from the wall. Alternatively, the outflowing air may be directed towards such a wall and to let the air stream bounce back into the room. In case the device is mounted at a wall, it may direct the outflowing air downwards towards the floor, where it is deflected so as to follow the floor surface away from the wall. In this way, the air velocity will be reduced, but the momentum of the air stream will be maintained and the fresh air will be effectively distributed into the lower part of the room. Such a ventilation arrangement will be perceived as comfortable to human beings being present in the room. The distance between the ventilation grid and the adjacent wall or floor may be 0.2-1.0 m (possibly between 0.3 and 0.9 m), in either of these possible arrangements. The air flow velocity at the outlet end of the ventilation grid unit may be in the interval 2.5 m/s to 6.0 m/s, possibly between 3.0 and 5.0 m/s.
The ventilation grid unit may comprise at least two air guiding profile elements made of an aluminium alloy or some other durable material which is easy to manufacture.
These and other features of the invention are indicated in the appended claims and will be apparent from the detailed description below.

Brief description of the drawings

The invention will be explained further below with reference to the appended drawings, illustrating an embodiment of the invention.

Figure 1 shows, in a view from above, a ventilation grid unit forming part of an air supply device according to the invention;
Figure 2 shows an air supply device according to the invention, in a vertical section through the floor of a room to be ventilated; and
Figure 3 shows, in a larger scale, a modified ventilation grid unit having only a small number of air guiding profile elements.

Detailed description of a preferred embodiment

Figure 1 and 2 illustrate an air supply device according to the invention, the device being mounted in a floor of a room to be ventilated. The upper floor surface 1 is horizontal. Only a small part of the floor is shown in figure 2. It is assumed that exhaust air devices are arranged adjacent to the ceiling of the room.
A box-like chamber 2 is constructed below the floor surface 1, and in this chamber there is mounted, below the floor surface 1, a longitudinal air supply unit, e.g. of the kind disclosed in the Swedish patent application No. 0900359-1 (Inventiair AB). Thus, the air supply unit comprises a box-like casing 3, a feed tube 4 for feeding supply air, and an air supply opening 5 being directed horizontally into an adjacent air feed chamber 6 which is also box-like in shape. At the top of the air feed chamber 6, a ventilation grid unit 7 is mounted as a lid on the box-like chamber 6, with its upper surface portions 8f, 9a (fig. 3) lying flush with the floor surface 1. The ventilation grid unit 7 is also shown from above in figure 1. Typically, the ventilation grid unit has a length of 0.5 to 1.0 m and a width of 0.2 to 0.5 m.
The air guiding profile elements 8 have a height of 30 mm to 40 mm, and the free distance between any two adjacent guiding profile elements 8 is about 15 mm to 25 mm, measured as the free distance therebetween, at the uppermost and lowermost points. The profile elements 8 are held together by transverse holding elements 12, e.g. in the form of tubes or bars.
Basically, fresh air will be supplied through the feed tube 4 and will flow out through the opening 5 (arrow A), upwardly through the ventilation grid 7 (arrows B) and thereupon along the floor in accordance with the arrows C. Accordingly, the outwardly flowing air stream is guided and deflected by means of the curved air guiding profile elements 8 forming parts of the ventilation grid unit 7. In figure 3, these air guiding profile elements 8 are shown in a larger scale. Each profile element, made of a durable aluminium alloy, has a lower, approximately straight portion 8a, an adjoining, slightly curved mid portion 8b, a step portion 8c, an adjoining, curved upper portion 8d, and an upper end portion 8e, which is tapered into a longitudinally extending edge.
The stepped portion 8c has a step surface on both sides, i.e. on the concave side (to the left in figure 3) as well as on the convex side (to the right in figure 3). Because of the stepped portion 8c, the effective curvature of the profile element will increase at the upper part of the profile element, and there is a further effective curvature at the longitudinally extending edge 8e. As will be seen from figure 3, there is an upper horizontal surface portion 8f and a lower, very short surface portion 8g, which is likewise substantially horizontal.
Thus, the surface portions 8f and 8g are, in this embodiment, substantially parallel to the floor surface 1. As indicated above, these surface portions, corresponding to 8f and 8g, may alternatively be oriented at a small angle relative to the floor surface, such as up to 15°, preferably less than 5° at the upper side (8f) and less than 10° at the lower side (8g).
It will be understood that the air flowing upwards through the ventilation grid unit 7 (arrows B in figure 2) will be increasingly deflected by the profile element portions 8b, 8c, 8d and 8e, so that the resulting air stream outside the ventilation grid unit 7 is approximately horizontal or parallel to the floor, as illustrated by arrows C in figure 2. It is well known that such an air stream, flowing almost in parallel along a surface (in this case the floor surface 1), will adhere to that surface and stay in parallel to the surface, by the so called Coanda effect.
Practical tests have shown that the air stream along the floor surface 1 will be confined to an air layer at a vertical distance above the floor between 20 mm and 100 mm, in particular between 30 mm and 90 mm.
Apart from being deflected sideways by the air guiding profile elements 8, the outwardly flowing air (arrows B) will be influenced by the stepped profile portion 8c, thereby causing a certain turbulence locally within the air stream. Such turbulence will facilitate an effective interaction between the ambient air in the room and the horizontal air stream C along the floor surface, while maintaining the momentum of the horizontal air stream and ensuring a uniform distribution of the fresh air throughout the room. Any persons being present in the room will cause a local upward stream of convection air, and this upwardly flowing air will be effectively replaced by fresh air from underneath. Because of the diffuse turbulence of the fresh air stream, any difference in temperature between the fresh air and the air in the room, will be equalized. Therefore, the room climate will be pleasant and comfortable, and there will be no feeling of draught, even though the horizontal air stream has a relatively high velocity. As mentioned above, this air stream will be confined to a rather narrow layer very close to the floor (or wall surface).
The supply air may have about the same temperature as the average room temperature, in case the room temperature is at a moderate level, such as 20°C. However, normally, there will be a need for supplying somewhat warmer air, in cold climates, or cool air, in hot climates or during a warm season of the year. Such warming or cooling of the air being fed to the air supply device can be achieved by heat exchangers 10, 11 arranged in the air supply device.
Furthermore, as a practical measure, the profile element 9 situated at one end of the ventilation grid unit 7 may be provided with an extended horizontal surface 9a which adjoins to the floor surface 1 and covers a dead zone of the outlet opening of the ventilation grid unit 7.
As indicated above, the ventilation grid unit may, as an alternative, be mounted at a wall of a room, so as to blow fresh air downwardly towards the floor where the air stream will be deflected and will continue because of its high flow velocity and momentum, to propagate along the floor surface. Of course, in large rooms, it may be preferable to mount a number of such units at some mutual distance from each other, such as 3-6 m between them.

Claims

An air supply device for supplying fresh air at a surface, such as a wall or a floor, of a room to be ventilated, comprising a ventilation grid unit (7) being arranged substantially flush with said surface (1), said ventilation grid unit being provided with a set of air guiding profile elements (8) oriented in parallel to each other and having a curved cross-sectional profile, so as to guide an air stream (B) into a direction having a component (C) in parallel to said surface, characterised in that
- said air guiding profile elements (8) are curved to a tangential angle at each outlet end (8e) being less than 15° relative to said surface (1), so that the air stream flowing out from said ventilation grid unit (7) is deflected into an air flow (C) being substantially parallel to said surface and forming a steady flow layer at a distance of at least 20 mm and no more than 100 mm from said surface (1),

- the flow velocity of said outwardly flowing air stream (B), at the outlet end of said ventilation grid unit (7), is at least 2.5 m/s, so that the resulting air stream (C) will propagate along said surface (1) with a high momentum, and

- each of said air guiding profile elements comprises a step-like irregularity (8c) along its length, forming a step in the direction of the outwardly flowing air-stream, at least on one side of said profile element (8), said step causing a turbulence in said outwardly flowing air-stream so as to enhance mixing and heat exchange between said air stream (C) and the ambient air in said room.
An air supply device as defined in claim 1, wherein said outlet ends of said profile elements (8) are tapered into a longitudinally extending edge (8e).
An air supply device as defined in claim 2, wherein said longitudinally extending edge (8e) has a tangential direction, at the external and internal sides, being less than 10° relative to said surface.
An air supply device as defined in claim 3, wherein said longitudinally extending edge (8e) has a tangential direction being less than 5° at the external side and less than 10° at the internal side, relative to said surface (1).
An air supply device as defined in claim 4, wherein the tangential direction is substantially parallel to said surface (1) at said external side as well as at said internal side of said longitudinally extending edge (8e).
An air supply device as defined in claim 1, wherein said distance to said surface is between 30 mm and 90 mm.
An air supply device as defined in claim 1, wherein said ventilation grid unit (7) is arranged in the floor adjacent to a wall of said room, said air guiding profile elements (8, 9) extending in parallel to said wall, and said outwardly flowing air stream (C) is directed towards or away from said wall, the horizontal distance between said ventilation grid unit (7) and said wall being 0.2 - 1.0 m, and the flow velocity in said horizontal air stream (C), at the outlet end of said ventilation grid unit, is in the interval 2.5 m/s to 6.0 m/s.
An air supply device as defined in claim 7, wherein said horizontal distance to said wall is between 0.3 and 0.9 m.
An air supply device as defined in claim 1, wherein said flow velocity is between 3.0 and 5.0 m/s.
An air supply device as defined in claim 1, wherein said ventilation grid unit comprises at least two air guiding profile elements (8) made of an aluminium alloy.
An air supply device as defined in claim 1, wherein each of said air guiding profile elements (8) comprises a step-like irregularity (8c) at its concavely curved side as well as at its convexly curved side.
An air supply device as defined in claim 1, wherein said ventilation grid unit (7) has a length of 0.5 to 1.0 m and a width of 0.2 to 0.5 m.
An air supply device as defined in claim 1, wherein each air guiding profile element (8) has a height of 30 mm to 40 mm, there being a free distance of 15 mm to 25 mm between any two adjacent guiding profile elements, measured as the free distance therebetween at the external and internal ends (8a, 8e).
An air supply device as defined in claim 1, wherein said ventilation grid unit (7) is arranged adjacent to a box-like air supply unit (3) having an air feed outlet opening (5) feeding fresh air into an adjacent air feed chamber (6), said ventilation grid unit forming an upper lid of said air feed chamber (6).