WO2005075897A1

WO2005075897A1 - Supply air device

Info

Publication number: WO2005075897A1
Application number: PCT/SE2005/000128
Authority: WO
Inventors: Göran Hultmark
Original assignee: Lindab Ab
Priority date: 2004-02-10
Filing date: 2005-02-03
Publication date: 2005-08-18
Also published as: RU2006132343A; EP1714090A1; SE0400300L; EP1714090B1; SE527956C2; RU2375645C2; SE0400300D0

Abstract

A device in connection with supply air ventilation, especially in connection with cooling baffles, comprises openings through which supply air flows in use. The device further comprises two duct portions (1, 2) whose mutual contact portions define said openings.

Description

SUPPLY AIR DEVICE

Field of the Invention The present invention relates to a device in connection with supply air ventilation, especially in connection with cooling baffles, comprising openings through which in use supply air flows.

Background Art Devices of the above type are frequent and normally used as cooling devices positioned in ceilings in, for example, offices. The nozzles can be punched openings in a duct which is placed in a suitable position along the device to obtain induction. If the supply air flowing out of the nozzles is directed in a certain direction, air from the ventilated space will be drawn there since the static pressure will be lower there as the dynamic pressure increases. By also arranging the nozzles in a special way, the air from the ventilated space can be directed so as to pass a cooling unit/cooling-coil battery and thus be cooled. As a rule, these so-called cool- ing baffles are arranged in such a manner that the air flowing out of the cooling baffles flows along the ceiling due to induction which in this case is usually called the Coanda effect. Different air flow rates are required in different spaces, and the air flow rate is adjusted to avoid that cooling baffles in all conceivable dimensions have to be manufactured. The supply air flow rate can be adjusted in various ways. One technique involves throttling the supply air even before it reaches the cooling baffle arrangement. In practice this technique functions poorly since the cooling baffles are designed to handle a specific pressure above atmospheric, for instance 60 Pa. Since the pressure is a square function of the air flow rate in turbulent flow, a small reduction in the flow rate will thus result in a comparatively much greater pressure reduction. If, for instance, the initial pressure is 60 Pa for a certain flow rate, and the flow rate is halved, the pressure will drop to about 15 Pa. This in turn results in the air velocity from the cooling baffle not being sufficient to create the desired induction, and thus such a cooling baffle does not function as intended. Another solution involves instead adjusting in various ways the number of nozzles and/or the size of the opening area of the nozzles. In plugging up, plugs, usually made of rubber, are used to plug up a number of the nozzles and thus adjust the supply air flow rate as desired. Such plugging up is generally performed when manufacturing the unit in order to adjust the performance of the unit to the available space where the unit is intended to be arranged. Plugging up gives, however, a number of drawbacks, one being that plugging up is time-consuming and costly. When plugging up more than 10-20% of the nozzles, the method often cannot be justified economically. Fur- thermore this method does not allow rational adjustment of the air flow rate of an already installed unit. Such adjustment may be desirable since the climate where the unit is placed varies, or since the need for cooling and/ or ventilation in some other manner has changed. To solve the problem with adjustments of installed units, there are solutions which basically involve adjustment of the opening areas of the nozzles by throttles. Since a unit in most cases has a large number of nozzles, these throttles are usually interconnected so that the opening areas of all nozzles are adjusted at the same time. A problem with this method of adjustment, in addition to the complexity of the throttle system, is that it also requires a specific design which means that the static pressure is poorly utilised when the air flows out of the nozzles and is partly converted to dynamic pressure. For optimal function, the nozzles should be designed so that as much as possible of the static pressure above atmos- pheric in the unit is converted to dynamic pressure. However, the solutions that are available today are not the most optimal in this respect.

Summary of the Invention The object of the invention therefore is to provide a device in connection with supply air ventilation which solves the above problems and which besides allows greater freedom with regard to adjustment of the size of the opening areas of the openings. According to the invention, this object is achieved by the device of the type stated by way of introduction being given the features that are defined in claim 1. Preferred embodiments of the device are defined in the dependent claims. The inventive device in connection with supply air ventilation, especially in connection with cooling baffles, comprises openings through which supply air flows in use. Moreover the device comprises two duct portions whose mutual contact portions define said openings. Contact portions refer to the boundary between, for example, two duct halves, i.e. where the duct is divided longitudinally. One of the advantages thus is that the duct need not be sealed. As a rule, a duct is manufac- tured of two or more sheet metal parts that are joined, and the joint must be sealed so as to prevent losses. By now instead using the fact that the duct is made of a plurality of parts, sealing of the duct is avoided, and moreover openings are obtained in a natural manner since the "leakiness" between the sheet metal parts is used as openings. Nozzles/openings are usually punched in the duct made of two or more sheet metal parts. The description of the invention uses the term "contact portion" to designate the area in the longitudinal direction along the duct portions which constitutes the contact area between two duct portions. In a preferred embodiment of the present invention, the position of the duct portions relative to each other defines the size of the openings. In other words, the distance between the duct portions adjacent to a contact portion controls the size of the openings. In a preferred embodiment of the present invention, said duct portions are movably arranged relative to each other in such a manner that the duct portions are slid- ably arranged relative to each other adjacent to the con- tact portions. In this way, the opening areas of the openings can be adjusted by only moving one duct portion relative to the other. Preferably, one of the duct portions comprises, adjacent to said contact portions, means arranged to define, in use, nozzles between the duct por- tions. Thus, the distance between the duct portions adjacent to the contact portions can be adjusted and, hence, the opening areas of the nozzles. Said means preferably consist of lugs arranged at a distance from each other along the contact portions, the opening area of the nozzles being greatest in a first position where the second duct portion rests on the first duct portion with lugs where the lugs are highest, and smallest in a second position when the edge of the second duct portion rests outside the lugs of the first duct portion. The lugs can easily be formed in one of the duct portions, for example, by compression moulding. The air flows between neighbouring lugs since the lugs on one of the duct portions raise the other duct portion. Preferably, said lugs comprise at least one field at an angle relative to the first duct portion, one of the edges of the field being aligned with the first duct portion, and the opposite edge of the field being spaced from the plane of the first duct portion to allow continuous adjustment of the opening areas of the nozzles. Thus, the distance between the duct portions can be adjusted continuously and, hence, also the opening areas of the nozzles. A further advantage of using so-called lugs is that they decrease the requirement for the tolerance of the duct portions. When manufacturing a longer duct portion, it may be difficult to obtain the desired tolerance. Using lugs, the lugs control the tolerance, i.e. the lugs control the duct portions so that the duct portions can be manufactured without requiring great tolerances, which also makes manufacture less expensive. In yet another preferred embodiment of the present invention, the lateral edges of said lugs are, at least at the ends of the contact portion, arranged at an angle relative to the sides of the lugs in the centre of the contact portion for controlling the direction of air from the device. This means that it is possible to control the two-dimensional spreading of the supply air from the device. When all lugs are arranged in parallel, the air flow from the device will, due to induction, collect to an air flow having a small cross-sectional area and, thus, a high air velocity, which if the worst comes to the worst may cause draught in the zone of residence, i.e. after the air has left the baffle. By angling the lateral edges of the lugs at the ends of the device outwards from the centre, the supply air spreads in several directions and will thus have a larger cross-sectional area and, hence, a lower air velocity, which reduces the risk of draught. It has been found particularly advantageous to have a device in which the sides of the lugs along the contact portion are fan-shaped for controlling the direction of air from the device. With this design, the air velocity is relatively even along the entire device. An alternative to angling the lateral edges is to incline all lugs completely where it is desirable to have inclined lateral edges. The greatest advantage of this alternative is that the same type of lug can be used along the entire device. In an alternative embodiment of the device, said means consist of depressions arranged at a distance from each other along the contact portions, the opening area of the nozzles being greatest when the edge of one duct portion is in contact with the other duct portion where the depth of the depressions in the second duct portion is greatest, and smallest when the edge of the second duct portion rests at the side of the depressions on the first duct portion. With this solution, the air thus flows in the depressions of one duct portion and around the edge adjacent to the contact portions of the other duct portion. Preferably, said depressions have one field at an angle to the plane of the duct portion with one of the edges of the field aligned with the plane of the duct portion and the opposite edge of the field spaced from the plane of the duct portion to allow continuous adjustment of the opening areas of the nozzles. In another alternative embodiment of the present invention, the sides of said depressions at least at the ends of the contact portion are arranged at an angle relative to the sides of the depressions in the centre of the contact portion for increased control of the direc- tion of air from the device. This means that it is possible to control the two-dimensional spreading of the supply air from the device. When all depressions are arranged in parallel, the air flow from the device will, due to induction, collect to an air flow having a small cross-sectional area and, hence, a high air velocity, which if the worst come to the worst may cause draught in the zone of residence, i.e. after the air has left the baffle. By angling the sides of the depressions at the ends of the device outwards from the centre, a negative induction effect is avoided and the supply air spreads in several directions and will thus have a larger cross- sectional area and, hence, a lower air velocity, which reduces the risk of draught in the zone of residence. It has been found particularly advantageous to have a device in which the sides of the depressions along the contact portion are fan-shaped for controlling the direction of air from the device. The air velocity of the air after leaving the baffle is with this design relatively even along the entire device. In a preferred embodiment of the present invention, at least one of the duct portions has corrugations at the nozzles for increased control of the direction of air from the device. In practice, it is hardly ever required that the nozzles be closed completely, and with corrugations slightly more rounded nozzles are obtained. Such rounded nozzles thus have a slightly less angular cross- sectional area, which further promotes the reduction of losses in the conversion from static pressure to dynamic pressure. Just like in the case of the lugs and the depressions in one duct portion, it is possible to angle the corrugations in the same way in the other duct por- tion to distribute the supply of air and most advantageously in the shape of a fan. By fan shape is meant throughout the text that the angle is changed gradually along the contact portions. In an alternative embodiment, at least one duct portion has cut-outs adjacent to the contact portions for increased control of the direction of air from the device. As an alternative to corrugations, for instance semicircular portions are in this case punched from the edge of one of the duct portions in order to round the cross-section of the nozzles. Such cut-outs can advantageously be asymmetric along the contact portions in order to, for example, additionally reinforce the control of the air direction from the device. In yet another preferred embodiment according to the present invention, the device is adjustable in such a manner that the position of the duct portions relative to each other is variable along the contact portion to allow adjustment to different air flow rates from the device along the device. Thus, the air flow rate can be varied along the contact portion, which may be advantageous in some applications, such as in spaces which are irregular in shape, or if the positioning of the device cannot be selected quite freely, thus requiring adjustment of the air flow rate. In one more alternative embodiment of the present invention, an element is movably arranged between said duct portions adjacent to the contact portions to allow adjustment of the size of said openings. In yet another alternative embodiment of the invention, the duct portions are movable sideways relative to each other. In this manner, the size of the openings can be adjusted since the corrugations or cut-outs place themselves over the lugs when the duct portions are moved sideways relative to each other, thus reducing the opening area between the duct portions.

Brief Description of the Figures The invention will in the following be further described by way of an embodiment with reference to the accompanying Figures. Fig. 1 is an exploded perspective view of a device according to the present invention. Fig. 2a is a partial cross-section of a device according to the present invention with the duct portions in a first position. Fig. 2b is an enlargement of B in Fig. 2a. Fig. 3a is a partial cross-section of a device according to the present invention with the duct portions in a second position. Fig. 3b is an enlargement of B in Fig. 3a. Figs 4a and 4b show a part of the contact portion, in an embodiment of the device, between two duct portions in a first and a second position respectively. Figs 4c and 4d show a part of the contact portion, in an alternative embodiment of the device, between two duct portions in a first and a second position respec- tively. Figs 5a and 5b show a part of the contact portion, in an alternative embodiment of the device, between two duct portions in a first and a second position respectively. Figs 5c and 5d show a part of the contact portion, in yet another alternative embodiment of the device, between two duct portions in a first and a second position respectively. Fig. 5e shows another alternative embodiment of the device in a fully open position. Fig. 6 is a spreading picture of the air flowing in parallel from the supply air device. Fig. 7 is a spreading picture of the air when the spreading is directed with a fan shape of the means adjacent to the contact portion in the device. Figs 8a and 8b illustrate in cross-section the con- tact portion in an alternative embodiment of the device, between two duct portions in a first and a second position respectively. Figs 9a and 9b illustrate in cross-section another alternative embodiment of the device according to the present invention with a slidable element between the duct portions in a first and a second position respectively .

Description of Preferred Embodiments The device in Fig. 1 comprises two duct portions 1, 2 and two cooling-coil batteries 3, which are some of the parts included in a cooling baffle according to the present invention. The upper duct portion 1 comprises lugs 4 along the duct portion 1. Fig. 2a shows the parts from Fig. 1 in a partial cross-section when the duct portions 1, 2 are in a first position relative to each other, where the duct portions seal against each other adjacent to the contact portions, i.e. the opening areas of the nozzles are minimal. Fig. 2b is an enlargement of the portion B in Fig. 2a. The opening areas of the nozzles are the largest in the position shown in Fig. 3a when the lower duct portion 2 has been moved upwards. In this position, the edges of the lower duct portion 2 rest on the upper part of the lugs 4, see Fig. 3b, which is an enlargement of B in Fig. 3a, and the air can flow between the lugs 4 when the device is in operation. Furthermore the lower duct portion 2 can be moved continuously between these two positions, thus obtaining continuous variation of the opening areas of the nozzles. The air is supplied in use at least at one end of the duct 8 and then flows between the two duct portions 1, 2, as indi- cated by the arrows 9. The air flows on and out between the lugs 4, as indicated by the arrow 10 in Fig. 3b. Due to induction, air is drawn from the room through the cooling-coil batteries 3, see the arrows 11 in Fig. 3a, and cooled indoor air is mixed with air from the cooling baffle and supplied to the room, see the arrows 12 in Fig. 3a. Figs 4a and 4b show a part of the device from Figs 2 and 3 in perspective. It is evident from Fig. 4b how the air flows out of the nozzles. Correspondingly, Figs 4c and 4d show how the air flows in the embodiment with depressions 7 instead of lugs as in Figs 4a and 4b. Figs 5a and 5b show the same part of the device as in Figs 4a and 4b, with the difference that the lower duct portion 2 in this case adjacent to the contact portions has corrugations 5 between the lugs of the upper duct portion 1. As mentioned above, this helps to obtain a still smoother conversion from static pressure to dynamic pressure and, consequently, better utilisation of the pressure. Another conceivable variant is to move one of the duct portions sideways, i.e. so that the corrugations 5 place themselves over the lugs 4, thus adjusting the air flow rate. Figs 5c and 5d illustrate an alternative embodiment corresponding to Figs 5a and 5b, where the corrugations have been replaced by cut-outs 13. The cut-outs 13 can, as shown in Figs 5c and 5d, be asymmetric to obtain increased control of the air from the device. Another purpose is to obtain, just like with the corrugations, a smoother conversion of the air when passing out of the baffle. Furthermore, Fig. 5e shows an alternative embodi- ment to the one shown in Figs 5c and 5d. The difference is here that the lugs are somewhat turned relative to each other (cf. fan-shaped) to achieve an increased possibility of directing the air out of the device. Figs 6 and 7 illustrate schematically the air velo- city along a device according to the present invention depending on the configuration of the lugs. In Fig. 6, all lugs are arranged in parallel, which often results in the air velocity varying along the device and, due to induction, being maximal in the centre since the indoor air helps to induce, as indicated by the arrows 14. To reduce the effect of induction, it is convenient to arrange the lugs in a fan-shaped manner in Fig. 7. In this way, a more even velocity profile is obtained along the device and consequently a lower air velocity. Figs 8a and 8b show an alternative embodiment of the invention where the lower duct portion is slidably arranged adjacent to the contact portion in such a manner that it can slide vertically without having to flex, i.e. the contact portion is parallel to the sliding direction. Figs 9a and 9b illustrate another alternative embodiment of the invention. An element 6 is slidable along the contact portion between the duct portions 1, 2, Fig. 9a showing the element 6 in a lower position where air cannot leave. In Fig. 9b, the element 6 is in an upper position where air can flow out between the lugs.

Of course, it is possible to adjust the size of the openings by arranging the element 6 in a position between the positions shown in Figs 9a and 9b. It will be appreciated that many modifications of the above-described embodiments of the invention are conceivable within the scope of the invention as defined by the appended claims . For instance, as described above with reference to Figs 1-3, a horizontally arranged cooling-coil battery may replace the illustrated two vertically arranged batteries. Consequently, also the rest of the construction must be adjusted to a horizontal cooling-coil battery in such a solution.

Claims

1. A device in connection with supply air venti- lation, especially in connection with cooling baffles, comprising an elongate duct having openings, through which in use supply air flows away from the duct, c h a r a c t e r i s e d in that the duct further comprises two duct portions (1, 2), whose mutual contact portions extend along the longitudinal direction of the duct and which contact portions define said openings, said duct portions (1, 2) being movably arranged relative to each other in such a manner that the duct portions (1, 2) are slidably arranged relative to each other adjacent to the contact portions.

2. A device as claimed in claim 1, in which the position of the duct portions (1, 2) relative to each other defines the size of the openings.

3. A device as claimed in claim 1 or 2, in which one of the duct portions (1, 2) comprises, adjacent to said contact portions, means (4) which define nozzles between the duct portions adjacent to said contact portions.

4. A device as claimed in claim 3, in which said means consist of lugs (4) arranged at a distance from each other along the contact portions, the opening area of the nozzles being greatest in a first position where the second duct portion (2) rests on the first duct portion (1) with lugs (4) where the lugs (4) are highest, and smallest in a second position when the edge of the second duct portion (2) rests outside the lugs (4) on the first duct portion (1) .

5. A device as claimed in claim 4, in which said lugs (4) comprise at least one field at an angle relative to the plane of the first duct portion (1) adjacent to the lug, one of the edges of the field being aligned with the plane of the first duct portion, and the opposite edge of the field being spaced from the plane of the first duct portion (1) to allow continuous adjustment of the opening areas of the nozzles.

6. A device as claimed in claim 4 or 5, in which the lateral edges of said lugs (4) are, at least at the ends of the contact portion, arranged at an angle relative to the sides of the lugs (4) in the centre of the contact portion for controlling the direction of air from the device .

7. A device as claimed in any one of claims 4-6, in which the lateral edges of the lugs (4) along the contact portion are fan-shaped for controlling the direction of air from the device.

8. A device as claimed in claim 3, in which said means (4) consist of depressions (7) arranged at a dis- tance from each other along the contact portions, the opening area of the nozzles being greatest when the edge of one duct portion is in contact with the other duct portion where the depth of the depressions (7) in the second duct portion is greatest, and smallest when the edge of the second duct portion rests at the side of the depressions on the first duct portion.

9. A device as claimed in claim 8, in which the depressions have at least one field at an angle to the plane of the duct portion with one of the edges of the field aligned with the plane of the duct portion and the opposite edge of the field spaced from the plane of the duct portion to allow continuous adjustment of the opening areas of the nozzles.

10. A device as claimed in claim 8 or 9, in which the sides of said depressions at least at the ends of the contact portion are arranged at an angle relative to the sides of the depressions in the centre of the contact portion for controlling the direction of air from the device .

11. A device as claimed in any one of claims 8-10, in which the sides of the depressions along the contact portion are fan-shaped for controlling the direction of air from the device.

12. A device as claimed in any one of claims 1-11, in which at least one of the duct portions (1, 2) has corrugations (5) at the openings for increased control of the direction of air from the device.

13. A device as claimed in any one of claims 1-11, in which at least one of the duct portions (1, 2) has corrugations (5) at the openings for increased control of the direction of air from the device, at least one of the corrugations (5) being angled relative to the others along the contact portion.

14. A device as claimed in any one of claims 1-11, in which at least one of the duct portions (1, 2) has corrugations (5) at the openings for increased control of the direction of air from the device, the corrugations (5) being angled in such a manner that they are fan-shaped along the contact portion.

15. A device as claimed in any one of claims 1-14, in which at least one duct portion (1, 2) has cut-outs adjacent to the contact portions for increased control of the direction of air from the device.

16. A device as claimed in claim 15, in which said cut-outs are asymmetric along the contact portions.

17. A device as claimed in any one of claims 1-16, which is adjustable in such a manner that the position of the duct portions (1, 2) relative to each other is variable along the contact portion to allow adjustment to different air flow rates from the device along the device.

18. A device as claimed in any one of claims 1-17, in which an element (6) is movably arranged between said duct portions adjacent to the contact portions to allow adjustment of the size of said openings.

19. A device as claimed in any one of claims 12-16, in which the duct portions are movable sideways relative to each other.