AIR CONDITIONING UNITS
A ducted unit having first and second outlets wherein the first and second outlets are connected to each other by outlet ducting to form a closed loop, the outlet ducting having at least two spaced apertures for ejecting air within the outlet ducting at substantially constant pressure such that the air pressure within the closed loop outlet ducting is substantially equalized such that the outlets operate at a substantially constant pressure.
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The present application relates to an improved air conditioning unit and in particular, although not exclusively, to an air conditioning unit suitable for recording studios, home cinemas and other noise sensitive areas.
There is a need for substantially silent air conditioning units, especially in the context of noise sensitive areas such as recording studios, sound recording booths or audio booths used for conducting hearing tests, home cinemas and the like. Such rooms are designed to block out as much external noise as possible and require any equipment within the room to work at minimal sound levels. For this reason, the walls of such audio booths are generally very thick and substantially soundproofed, meaning that they can get very hot, especially when the room is occupied for a long period of time. Such hot conditions may lead to extreme discomfort for the occupiers, and may furthermore cause excessive sweating which in itself leads to drips causing undesirable background noise which may interfere with the function of the sound-proofed room. Therefore some form of cooling within the sound-proofed room is essential.
At present, large and complex fan-assisted air conditioning systems are employed. Such air conditioning units comprise a refrigeration unit and a ducted unit. The refrigeration unit is typically mounted on the outside of a building and supplies refrigerant to the ducted unit in a closed loop. The ducted unit has an air inlet and an air outlet with a circulation fan to draw air over a radiator (heat is removed by the refrigerant). Conduits run from the ducted unit to disperse the cooled air into the room being cooled.
Fan based ducted units are standard equipment, which typically, during operation, emit a noise of around 32 decibels. However, by using silencers and increasing the size of the ducting from around 200 millimetres diameter to 600 millimetres diameter, specific units have been able to operate at a noise level of around 19 decibels. However, the noise needs to be below about 12 decibels to be placed inside a recording studio. Consequently, at the moment, to achieve the necessary noise level, the ducted units are placed outside the recording studio and combined with silencing baffles within extensive ducting between the fan and sound-proofed room, which necessarily requires at least four holes through the sound proof recording studio each of around 600 millimetres diameter. This is undesirable as it reduces the sound proofing of the recording studio and also requires significant destruction during installation of the air conditioning unit. Moreover, such air conditioning systems require a large amount of space for the ducting and corresponding air handling system to feed “silent air” into the booth due to the long path needed to overcome the significant sonic vibrations caused by the fan. Furthermore it is necessary to keep the fan as far away from the audio booth as possible. This all leads to an inefficient use of space and also energy inefficient air conditioning since chilled air passing through such a long path is likely to heat up before it reaches the sound-proofed room.
The outlet of a standard ducted unit is typically connected to two or more conduits for dispersing the cooled air around the sound-proofed room. Here, each ducting has a series of exit apertures and a closed end. The pressure of cooled air ejected from the apertures furthest from the ducting and nearest the closed end tends to be a lower pressure than the pressure of the cooled air ejected from apertures nearer the ducted unit and further from the closed end. This creates an uneven pressure across the apertures. Importantly, apertures ejecting the cooled air at higher pressures and therefore higher speeds operate at a higher noise level.
U.S. Pat. No. 5,207,615, EP 0374527 and DE 2 649 279 all disclose ducted units in which conditioned air is ejected.
It is an aim of the present invention to attempt to overcome at least one of the above or other disadvantages. It is a further aim to provide a ducted unit able to operate at a noise level at or below the 12 decibel noise limit required by some noise sensitive areas.
According to the present invention there is provided an apparatus and method as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims, and the description which follows.
According to one aspect there is provided an improved ducted unit comprising a sound-insulated housing having a sound absorption coefficient of at least 0.05 W/m2 at 100 Hz and wherein the sound-insulated housing contains an air circulation unit to draw air through the ducted unit, wherein the air circulation unit is operated to spin between around 1000 and 750 revolutions per minute. Advantageously, it has been found that because the combination of sound-insulation and air circulation speed reduce the mechanical noise of the ducting unit, it is possible for the ducted unit to operate at a noise level of less than 10 decibels. Consequently, the ducted unit can be placed within a sound-proofed room. This is advantageous because it reduces the distance the air ejected from the outlet has to travel from the ducted unit to the room, which increases the efficiency when the ducted unit is used in an air conditioning system. Moreover, it is not necessary to form holes through the sound-proofed room for ducting to penetrate. Rather, when the ducted unit is used in an air-conditioning system, only in and out fluid pipes connecting a radiator element in the ducted unit to an external refrigeration unit are required. These pipes are significantly smaller than air ducting so requiring less disruption and sound leakage.
Sound absorption is defined as a co-efficient, ranging from 0.0 for total reflection, to 1.0 for total absorption. The sound absorptive properties of a material are defined in BS EN ISO 11654:1997, which gives three relevant properties: Sound Absorption Coefficient (αs), which are Individual sound absorption figures quoted in third octave frequency bands; Practical Sound Absorption Coefficient (αp), which are sound absorption figures quoted in single octave frequency bands; and Sound Absorption Rating (αΩ), which is a single figure rating based upon the values of (αp), compared to a reference weighting curve. It has been found that by lining the inside walls of the housing with a sound absorbing material, a sound-insulated housing is achieved which gives surprisingly suppressed noise. It is important that the using the third octave frequency band data, the sound insulating has a sound absorption coefficient of at least 0.05 W/m2 at 100 Hz.
In one exemplary embodiment, the sound absorbing material ha open cells or voids, through which the noise travels and is dissipated. However, in one exemplary embodiment, the inner most surface of the sound insulating over which the air travels is substantially continuous and flat. That is, the open cells or voids are closed, for instance with a silicone layer. This is beneficial as turbulence is not introduced in to the air flowing over the sound insulation, which would otherwise increase the noise of the air, whereas the noise energy in the air still permeates through the smooth layer and into the underlying voids for dissipation.
In the exemplary embodiments the sound-insulated housing provides an enclosure for the air circulation unit to be arranged between an inlet and an outlet, wherein operation of the air circulation unit causes air to be drawn through the inlet and expelled through the outlet. In one exemplary embodiment, the ducted unit is suitable for use in an air-conditioning system. Here, the sound-insulated housing comprises an enclosure suitable to arrange a radiator in the air flow. Consequently, by running refrigerant through the radiator, the air expelled from the outlet of the ducted unit can be cooled with respect to the inlet. Here, the ducted units are typically rated for their ability to extract heat. Although the combination of fan speed and insulation rating provide beneficial results for larger ducted units, they are particularly effective for 5 kW ducted units.
In the exemplary embodiments the air-circulation unit is suitably a fan having a rotating blade or blades.
In one exemplary embodiment, the ducted unit has a plurality of inlets. The ducted unit may also have a plurality of outlets. However, it is preferable if the ducted unit has more inlets than outlets as this reduced the air circulation noise. For instance in one particular exemplary embodiment, the ducted unit has three inlets and two outlets. The increase in area of the inlet as opposed to the area of the outlet means that the ducted unit has to work less hard to pull air into the unit, which reduces the sound generated by the air being sucked through the inlet(s). This goes against conventional wisdom that suggests that the area of the inlet should equal the area of the outlet so as to balance the system.
The ducting unit may be connected to inlet and outlet ducting, each having one or more inlets and outlets to a room, such as a sound-proofed room. Here, the inlet and outlet ducting lengthens the distance from the inlet and outlet of the ducted unit before the air is expelled into the room. In one exemplary embodiment, the ducted unit inlet and outlet ducting are provided as a single unit housed on a common frame. Consequently, the single unit needs limited installation other than being connected to the refrigerant (if used as part of an air-conditioning system).
In an alternative exemplary embodiment, the ducted unit comprises at least one pair of outlets. Here each outlet is connected to an outlet ducting having a plurality of apertures, wherein the outlet ducting of each outlet in said pair is connected to the other to form a substantially closed loop. Consequently, the air pressure within the closed loop outlet ducting is substantially equalised meaning that the outlets operate at a substantially constant pressure. It will be appreciated that the closed loop outlet ducting provides advantages when used independent to the exemplary ducted units and so according to a second aspect there is provided an improved ducted unit having first and second outlets of air wherein the first and second outlets are connected to each other by ducting to form a closed loop, the ducting having at least two spaced apertures for ejecting air within the ducting at substantially constant pressure.
In the exemplary embodiments, the outlet ducting has a substantially constant cross-section. The apertures are spaced along the closed loop outlet ducting so that apertures are spaced at varying distances from each outlet of the ducted unit. A particularly suitable ducting comprises 250 mm diameter ducting.
In the exemplary embodiments, at least 12 or at least 18 apertures are provided dependent on the specific design of the sound-proofed room. However, preferably the closed loop outlet ducting has at least 2 outlets apertures per kW that the ducted unit is rated to, which has been found to provide a particularly quite air distribution. In particular, for a 5 kW ducted unit, it is particularly suitable to provide 12 outlets or more. In the exemplary embodiments, the apertures are formed on nozzles or extensions to the closed loop outlet ducting. For instance, solid or flexible tubing may be arranged to extend from the closed loop outlet ducting in order to change the direction of airflow from one plane, for instance along a roof, to a second plane, for instance substantially downwardly. The apertures are suitably 80 mm diameter rings. The tubing extending from the outlet ducting may be substantially similarly sized. However, again it will be appreciated that the exact sizing will be dependent on the application. It has been found though that particularly low noise levels can be achieved using apertures having an area approximately 10% of the cross sectional area of the closed loop outlet ducting, though between 9% and 11% or 8% and 12% have also been found to be beneficial.
According to a further aspect, a first ducted unit is used in an air-conditioning system and a second ducted unit is used to supply fresh air. Particularly suitably, one or both of the first and second ducted units may be connected to a closed loop outlet ducting in accordance with previous aspects. Moreover, one or both of the ducted units may be located in a soundproofed room, wherein the ducted units are in accordance with previous aspects.
For a better understanding of the invention, and to show how embodiments of the same may be carried into effect, reference will now be made, by way of example, to the accompanying diagrammatic drawings in which:
Referring to
Typically, the housing 110 is formed from a box-like structure having a geometric shape for low cost manufacture. Here, sheet materials are welded to seal the seams of the housing. In
Optionally, and in accordance with a further exemplary embodiment, the ducted unit is suitably used within an air-conditioning system. Here the air-conditioning system includes a refrigerant supply 300, typically from an external refrigeration unit (not shown). Referring to
Referring to
Referring to
The cross sectional area of the exit aperture 182 and nozzle tubing 184 is shown as being substantially consistent. It has been found that when using a closed loop ducting 136 of around 0.25 meter diameter, it is particularly efficient to provide the exit aperture with a 0.08 meter diameter cross sectional area. Consequently, it is preferable for the exit aperture to have an area approximately 10% of the closed loop ducting. However, good results have also been achieved using areas of between 8% and 12% of the cross sectional area.
The apertures 180 may be spaced equally or unequally depending on the specific structure and use of the soundproofed room. However, it has been found that when using apertures as described above, a density of 2 or more apertures per kW that the ducted unit is rated is particularly suitable for achieving reduced airflow noise below the 10 decibel limit.
Preferably, and because it has been found to provide a particularly efficient cooling of the soundproofed room, the outlet ducting is arranged to expel air around a periphery of a room (see
Referring to
Referring to
Referring to
An air circulation unit 900 is provided at one end of the unit as shown in
The wing is divided by a plate 938. As shown in
A plurality of wings may be provided which may be clipped together such as by sliding the end of one wing over a projecting connector 946 of another wing.
One wing, which may be the end wing in a series of wings, may have a gap at the end of the plate to allow the air to change direction back towards the air conditioning unit in the direction of arrow 944.
The or each wing may be supported by a box 948, for instance by a downwardly projecting flange 950 extending into an upwardly projecting flange 952 on the side of the box 948.
The box 948 may be supported from above such as by wires extending from the ceiling.
Sections of a building, which may be a substantially enclosed building which may have an open side or top or a partially open side or top, may be cooled or heated to a greater extent than other sections. For instance an air conditioning unit may be suspended above the aisles of a supermarket to cool the aisles but to leave the shelves between the aisles largely uncooled. The system may maintain the aisles to within plus or minus 1° C. Accordingly the energy required to cool the supermarket is significantly less than that normally required to cool the supermarket when the whole area of the supermarket is cooled, it may also be possible to cool a marquee for instance by suspending a unit from the cross members of the marquee. Different sections may be cooled to different extents.
The air conditioning unit with the closed circuit may be used to cool the building. Alternatively or additionally different sections may be cooled without the closed circuit of a building. For instance the wings 932 may be suspended over the aisles of a supermarket without there being any return of the air to the air conditioning unit.
In a building, for instance, a supermarket, the length to be cooled may be such that two or more air conditioning units may be aligned above the aisle to adequately cool the aisle.
Attention is directed to all papers and documents which are filed concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference.
All of the features disclosed in this specification (including any accompanying claims, abstract and drawings), and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of such features and/or steps are mutually exclusive.
Each feature disclosed in this specification (including any accompanying claims, abstract and drawings) may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.
The invention is not restricted to the details of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.
Claims
1. A ducted unit having first and second outlets wherein the first and second outlets are connected to each other by outlet ducting to form a closed loop, the outlet ducting having at least two spaced apertures for ejecting air within the outlet ducting at substantially constant pressure.
2. The ducted unit of claim 1, wherein the closed loop outlet ducting comprises at least one section of ducting connected at each end to an outlet of a ducted unit.
3. The ducted unit of claim 1, wherein the closed loop outlet ducting has at least two outlet apertures per kW that the ducted unit is rated to.
4. The ducted unit of claim 1, wherein solid or flexible tubing is arranged to extend from the closed loop outlet ducting in order to change the direction of airflow from one plane to a second plane.
5. The ducted unit of claim 1, wherein each aperture has an area that is between 8% and 12% of the cross-sectional area of the closed loop outlet ducting.
6. The ducted unit of claim 1, wherein the ducted unit comprises a sound-insulated housing having a sound absorption coefficient of at least 0.05 W/m2 at 100 Hz and wherein the sound-insulated housing contains an air circulation unit to draw air through the ducted unit, wherein the air circulation unit is operated to spin between around 1000 and 750 revolutions per minute.
7. The ducted unit of claim 6, wherein the sound absorbing material has open cells or voids, through which the noise travels and is dissipated, with the inner most surface of the sound insulating over which the air travels being substantially continuous and flat.
8. The ducted unit of claim 1, further comprising a housing that provides an enclosure for an air circulation unit to be arranged between an inlet and an outlet, wherein operation of the air circulation unit causes air to be drawn through the inlet and expelled through the outlet.
9. The ducted unit of claim 8 suitable for use in an air-conditioning system, wherein the housing comprises an enclosure suitable to arrange a radiator in the air flow.
10. The ducted unit of claim 8, wherein the ducted unit has a plurality of inlets, and a plurality of outlets, the ducted unit having more inlets than outlets.
11. The ducted unit of claim 1, wherein the outlet ducting of two or more ducted units are connected together, the closed loop outlet ducting therefore being formed by a plurality of outlet ducting sections, with each outlet ducting section being directly connected at one end to one outlet and the other end to a different outlet.
12. The ducted unit of claim 1, wherein the outlet ducting is formed from a section having a first chamber for supply air and a second chamber for return air.
13. The ducted unit of claim 1, wherein the outlet ducting is formed from a section having a first chamber for supply air, wherein the section has a step formed on each outer side, wherein the side face of each step includes said apertures.
14. The ducted unit of claim 13, wherein the outlet ducting includes a second, separate chamber for supply air, wherein the first and second chambers are arranged parallel to each other and the apertures on one side face are connected to one chamber and the apertures on the other side face are connected with the other chamber.
15-39. (canceled)
40. An air conditioning system for a substantially enclosed building, the system comprising a plurality of air outlets arranged to emit conditioned air to cool or heat one section of a room included in the building to a different extent than another section of the room.
41. The system as claimed in claim 40 in which the outlets are provided on ducting suspended from above.
42. The system as claimed in claim 41 in which the conditioned air is arranged to heat or cool the aisle or aisles or a room of a building.
43. The system as claimed in claim 41 in which the ducting is elongate with the ducting including a lower passage and in which conditioned air is arranged to be emitted at least partially downwardly from the lower passage.
44. The system as claimed in claim 43 in which the ducting includes an upper passage and in which air is returned to the air conditioning unit via the upper passage.
45. The system as claimed in claim 43 in which the elongate ducting includes a plurality of ducting units that are connected together to comprise the elongate lower passage.
46. The system as claimed in claim 45 in which the units are connected together by a push fit.
47. The system as claimed in claim 45 in which each unit includes an upper and a lower passage.
48. The system as claimed in claim 47 in which an end unit has a flow passage connecting the upper and lower passages and in which conditioned air is arranged to flow from the air conditioning unit into and along the power passage and then back to the air conditioning unit via the upper passage.
49. The system as claimed in claim 43 in which the ducting includes two side by side ducts.
50. The system as claimed in claim 49 in which the side by side ducts are arranged to be supplied with conditioned air from the same air conditioning unit.
51. The system as claimed in claim 43 in which the ducting comprises a plurality of ducts each extending over a different elongate extent and each being supplied with conditioned air from a different source.
52. The system as claimed in claim 40 in which the ducting is arranged to be connected to supporting member which is suspended from above.
53. A method of cooling or heating at least one section of a room of a substantially enclosed building to a different extent than another section of the room comprising emitting air from a plurality of outlets to heat or cool that section.
54. The method as claimed in claim 53 comprising cooling or heating a section of a supermarket comprising an aisle of the supermarket by directing air downwardly towards the aisle through a plurality of outlets along substantially the complete extent of the aisle.
55. The method as claimed in claim 54 comprising heating or cooling different aisles to different temperatures.
Type: Application
Filed: Jul 24, 2012
Publication Date: Oct 16, 2014
Applicant: SILENTAIR GROUP LIMITED (Halifax)
Inventor: Phil Gillatt (Halifax)
Application Number: 14/234,784
International Classification: F24F 13/24 (20060101);