WO2005015090A1

WO2005015090A1 - Air cooling device

Info

Publication number: WO2005015090A1
Application number: PCT/GB2004/003310
Authority: WO
Inventors: John Lightfoot; Tony Hammersley; Keith Nicholls
Original assignee: Marstair Limited
Priority date: 2003-08-02
Filing date: 2004-07-30
Publication date: 2005-02-17
Also published as: GB0318144D0

Abstract

An air cooling device comprising a housing (4) having at least one air inlet aperture (16) and at least one air discharge aperture (17), a coil (3) having an inlet (13) and an outlet (14) for cooling liquid disposed within the housing (4) between the inlet and outlet apertures (16, 17) and a plenum (2) having an inlet (8) for receiving air under pressure from a ventilation system and having at least one exhaust nozzle (9) constructed to provide a stream of air at the air discharge aperture (17), the arrangement being such that the stream of air generates a negative pressure to draw air from the air inlet aperture (16), over the coil (3), and discharges the cooled air from the device with the air exhausting from the nozzle (9). This device does not require a fan or an additional cooling system to reduce the temperature of the cooling liquid.

Description

AIR COOLING DEVICE

This invention relates to an air cooling device, and in particular, a device known in the art as an active chilled beam.

Air cooling devices may be distinguished from air conditioning devices, which are used primarily to cool air within buildings or auditoria where there is insufficient natural cooling from _ open windows or when the required internal temperature cannot be obtained due to the climate. Typically, air conditioning devices comprise a heat exchanger that utilises a refrigerant or mechanically chilled water to cool air that is pumped over the heat exchanger. The refrigerant or chilled water is cooled by a condenser /heat exchanger or chiller, which may be located outside the building, to a temperature of less than 11°C, for example. Although this method provides effective cooling of air within the building, it is not energy efficient, as a relatively large amount of energy is required to cool the refrigerant or water. Air conditioning devices may also incorporate dehumidifiers and various filters for removing dust, to ensure correct humidity levels, and clean air.

An air cooling device only reduces the temperature of the air. A well known air cooling device comprises a box section pipe arranged in a rectangular shape for mounting within a false ceiling. This design is advantageous as it can be constructed and arranged to be accommodated in the area of a ceiling tile (600mm by 600mm, for example). A refrigerant or chilled water, typically of a temperature of less than 11°C, is passed through the pipe. This design uses a fan to provide the required flow of air from the room over the pipe to achieve an effective cooling rate. This device is known in the art as a fan coil device. The presence of a fan can cause increased noise and increases the energy consumption of the air cooling system. Further, each fan requires a power supply and thus each air cooling device requires electrical wiring, which is unfavourable.

An alternative common air cooling system utilises water that has been passed through a heat exchanger which has fresh air pushed across its surface and is known in the art as a chilled beam system. Water passed through the heat exchanger is typically around 14°C, and is passed through large beams mounted in the ceiling of a room. Although the temperature difference between the water and air to be cooled is not very great the beams have a very large surface area. The beams are typically

2 to 3 metres long or may span the length and breadth of large auditoriums or theatres, for example. Thus, warmer air rising in the room passes over the surface of the beam and transfers its heat to the circulating water. Air cooling devices of this type are only effective if their surface area is large, as this ensures that a sufficient air flow rate over the surface of the beam is achieved.

Many buildings have fresh air ventilation systems to supply rooms with clean, fresh air. The ventilation system may be arranged such as to promote the passage of rising warm air through the active chilled beam and the resulting cooler air through the room. Typically, the ventilation system is positioned above the beams and the exhausting fresh air is directed generally in the direction of the edges of the beams. Although a sufficient air flow rate is easier to achieve with this arrangement, the beams still need to have a large finned surface area to cool the air effectively. Nevertheless, these systems are much more energy efficient than air conditioning systems, but their size makes them difficult to install and for architects to accommodate them within the design of the building. Further, if the air is particularly warm or has high humidity, water vapour in the air condenses on the chilled beam and therefore water droplets can drip onto the occupants of the room. According to the present invention we provide an air cooling device comprising a housing having at least one air inlet aperture and at least one air discharge aperture, a coil having an inlet and an outlet for cooling liquid disposed within the housing between the inlet and outlet apertures and a plenum having an inlet for receiving air under pressure from a ventilation system and having at least one exhaust nozzle constructed to provide a stream of air at the air discharge aperture, the arrangement being such that the stream of air generates a negative pressure to draw the air from the or each air inlet aperture, over the coil, and discharges the cooled air from the air cooling device with the air exhausting from the nozzle.

An air cooling device having this arrangement does not require a fan or an additional cooling system to reduce the temperature of the cooling liquid. The controlled flow of air from the ventilation system generates a sufficient flow of air through the coil for effective air cooling. The device uses the negative pressure generated by the flow of air from the nozzle and through the discharge aperture to draw the air to be cooled through the coil. The nozzle ensures a more precise flow of air from the ventilation system than prior art designs, which allows the air cooling device of the invention to be energy efficient and compact. The device would typically be mounted in the void of a false ceiling, thereby receiving rising air from the room in the air inlet aperture. The air for supplying to the nozzle may conveniently be provided by a ventilation system. Ventilation systems are a requirement in many commercial buildings where the windows are usually kept closed, due to noise or pollution, or cannot be opened at all. Preferably, the plenum has a projecting section extending into the air inlet aperture and shaped to deflect incoming air toward the cooling coil. This promotes airflow over the coil and therefore the cooling efficiency of the air cooling device.

Preferably, the plenum has a plurality of nozzles extending into the air discharge aperture.

Preferably, the air cooling device includes a fascia that is attached to the housing, the fascia having a grille for allowing passage of air into the air inlet aperture and at least one discharge louvre for directing air from the discharge aperture.

If the air to be cooled is particularly humid, water vapour may condense and collect on the coil and then drip. It is therefore preferable that the body of the air cooling device includes a condensate tray located beneath the coil for collecting condensate liquid. The tray may be connected to a drainage system for removal of the condensate.

Preferably, the air discharge aperture comprises a plurality of slots arranged around the periphery of the air cooling device.

An embodiment of the invention is illustrated, by way of example, in the accompanying drawings, in which;

Figure 1 shows an exploded perspective view of an air cooling device;

Figure 2 shows a cross-section through the assembled air cooling device; and Figure 3 shows a perspective view of the plenum of the air cooling device.

An air cooling device 1 for mounting in a false ceiling of a building comprises a plenum 2, a coil 3, a chassis 4 and a fascia 5. The chassis 4 forms a housing for the air cooling device 1. The air cooling coil 3 is shown assembled with the plenum 2, to fit into the chassis housing 4. The plenum 2 comprises a substantially square base section 6 having a projecting central section 7 and an air inlet pipe 8 extending from the central section 7 to a corner of the plenum 2. The plenum 2 also has a plurality of nozzles 9 spaced around its periphery, projecting in the same direction as the central section 7, which is downward when the device is installed in the ceiling. The base section 6 of the plenum 2 has a metal base plate 10 for attachment to a permanent structure (not shown) when the air cooling device 1 is mounted in the false ceiling of a building or the like. The base plate 10 has connection means (not shown) for receiving mounting brackets, for example, to effect the attachment to the permanent structure.

The coil 3 comprises a finned pipe 11 that is coiled into a flat rectangle that is then bent into a substantially square shape having a gap 12 at a corner portion. The gap 12 allows the passage of the air inlet pipe 8, when the coil 3 is assembled with the plenum 2. The coil 3 is mounted between the central section 7 and the nozzles 9. The pipe 11 has an inlet 13 and an outlet 14 constructed and arranged for connection to external water supply and return lines at an edge portion of the air cooling device 1.

The chassis 4 is a substantially hollow box section having an outer wall 15, a main aperture 16 and four peripheral slots forming discharge apertures 17 formed adjacent each side portion of the chassis 4 by four inner wall sections 18. The outside dimensions of the chassis 4 are substantially equal to that of the plenum 2. The discharge slots 17 are vertically aligned with the nozzles 9. The outer wall 15 is constructed and arranged to fit around the outside of the nozzles while the inner wall sections 18 are arranged to contact the coil 3. The chassis 4 also has a slot 19 through the inner and outer walls 15, 18 to receive the air inlet pipe 8 when the chassis 4 is mounted together with the plenum 2 by attachment means (not shown) . The chassis 4 also has a further slot 20 through wall 15 to allow access to the inlet and outlet pipes 13, 14 of the coil 3.

The fascia 5 comprises a substantially square lamina attached to the chassis 4. The fascia 5 has a central slotted air inlet grille 21 of a size corresponding to the size of the central aperture 16 of the chassis 4. The fascia 5 also has an elongate discharge louvre 22 adjacent each peripheral side of the fascia 5. The discharge louvres 22 are arranged to be aligned with the discharge slots 17 when the fascia 5 is mounted to the chassis 4. The fascia 5 may be mounted to the chassis 4 by clips or by hinges.

Figure 2 shows the components of Figure 1 in an assembled arrangement. The central section 7 of the plenum 2 is constructed such that warm air, rising by convection through fascia air inlet grille 21 and air inlet aperture 16, is deflected towards the coil 3. The air inlet 8 (shown in dotted lines) extends through slot 19 in the chassis 4 for attachment to a fresh air source. The nozzles 9 extend between the outer wall 15 and coil 3 a distance equivalent to several turns of the coil pipe 11. The inner walls 18 are shown in more detail in Figure 2 and comprise a body section 23 having a stepped groove 24, 25. The groove 24, including its deeper step 25, is delimited on opposed sides by two spaced lips 26. The spaced lips 26 are constructed to receive the coil 3 within the groove 24. The deeper groove 25 forms a condensate tray for receiving any liquid that may have condensed on the coil 3. A lift pump (not shown) may be provided to pump condensate from the tray 25 to a condensate drain pipe 27 that exits the air cooling device 1 adjacent to the inlet 13 and outlet 14 of the coil pipe 11 through the slot 20.

The plenum 2 is shown, separate from the remaining components of the air cooling device 1, in Figure 3. The plenum 2 is a hollow integral moulding and has a cavity 28 formed therein. Air entering the cavity 28 via the air inlet 8 creates a pressure within the cavity 28, which exhausts through nozzle apertures 29 in the nozzles 9. The exhausting air passes through discharge channels 30 formed between the outer walls of the chassis 4 and the inner walls 18.

In use, the assembled air cooling device 1 is mounted within a false ceiling of, for example, a building by mounting brackets attached from the building to the connecting means on the base plate 10. The coil pipe inlet 13 is connected to a cold water feed which supplies water at a temperature of approximately 14°C. The water outlet 14 is also connected to the building's outgoing water system. The drain pipe 27 is connected to a drainage system of the building. The fresh air supply system of the building distributes air through the nozzle apertures 29 through the plenum 2.

Warmer air naturally rises towards the ceiling by convection and will enter the air cooling device 1 through the slotted air inlet grille 21 of the fascia 5. The warm air is therefore received in the air inlet aperture 16. The warm air is deflected toward the coil 3 by the central section 7 of the plenum 2. The nozzles 9 are constructed such that they generate a stream of fresh air through the discharge channels 30 and along the side of the coil 3. This stream of air causes a negative pressure in discharge channels 30 to draw the warm air from the air inlet aperture 16 through the coil 3 and thus between the coils of the finned pipe 11. As cold water is pumped through the coiled pipe 11 it acts as a heat exchanger. Thus, provided that the warm air temperature is higher than the cold water feed temperature, the water in pipe 11 absorbs heat from the warm air. The coiling arrangement of the pipe 11 and its fins increase its surface area, thereby increasing its effectiveness as a heat exchanger. Water leaving the pipe 11 via the outlet 14 is therefore warmer than the inlet water, typically around 17°C. The cooled air drawn through the coil 3 is ejected from the air cooling device 1 with the fresh air, which exhausts from the nozzles 9, through the discharge louvres 22. The discharge louvres 22 direct the outgoing, cooled air outwards from the centre of the fascia 5 to ensure the cooled air is circulated efficiently.

Claims

1. An air cooling device comprising a housing (4) having at least one air inlet aperture (16) and at least one air discharge aperture (17), a coil (3) having an inlet (13) and an outlet (14) for cooling liquid disposed within the housing (4) between the inlet and outlet apertures (16, 17) and a plenum (2), characterised in that the plenum has an inlet (8) for receiving air under pressure from a ventilation- system and at least one exhaust nozzle (9) constructed to provide a stream of air at the air discharge aperture (17), the arrangement being such that the stream of air generates a negative pressure to draw the air from the or each air inlet aperture (16), over the coil (3), and discharges the cooled air from the air cooling device (1) with the air exhausting from the or each nozzle (9).

2. An air cooling device according to claim 1 , characterised in that the plenum (2) has a projecting section (7) extending into the air inlet aperture (16) and shaped to deflect incoming air toward the cooling coil (3) .

3. An air cooling device according to claim 1 or claim 2, characterised in that the plenum (2) has a plurality of nozzles (9) extending into the air discharge aperture (16) .

4. An air cooling device according to any preceding claim, characterised in that the air cooling device (1) includes a fascia (5) that is attached to the housing (4), the fascia (5) having a grille (21) for allowing passage of air into the air inlet aperture (16) and at least one discharge louvre (22) for directing air from the discharge aperture (17) .

5. An air cooling device according to any preceding claim, characterised in that the body (4) of the air cooling device (1) includes a condensate tray (25) located beneath the coil (3) for collecting condensate liquid.

6. An air cooling device according to claim 5, characterised in that the tray (25) is connected to a drainage system for removal of the condensate.

7. An air cooling device according to any preceding claim, characterised in that the air discharge aperture comprises a plurality of slots (17) arranged around the periphery of the air cooling device (1).

8. An air cooling device of the kind set forth substantially as described herein with reference to and as illustrated in Figures 1 to 3 of the accompanying drawings.