Patent Application
20100247339
The invention generally relates to the field of Heating, Ventilation, Air Conditioning (HVAC) and refrigeration systems. More specifically, the invention relates to a device for attenuating noise in HVAC and refrigeration systems.
HVAC and refrigeration systems have applications in various domestic, industrial and commercial areas. Examples of HVAC and refrigeration systems include, but are not limited to, chillers, air handlers, and variable air volume terminal units.
For adequate cooling of large cooling spaces such as buildings, large capacity HVAC and refrigeration systems are used. Such HVAC and refrigeration systems typically include a compressor, a condenser, and an evaporator. Typically a scroll rotary compressor or a reciprocating compressor is used. The compressor functions to compress a refrigerant, which is then circulated through a condenser coil. A fan blows air across the condenser coil. The amount of cooling that is provided depends on various factors, such as the speed of the fans, and the number of fans used.
When the speed of the compressor is increased, the corresponding flow rate of the compressed refrigerant is increased. Therefore, to cool the refrigerant at an increased rate, a higher rate of heat exchange by the condenser is required. This rate of heat exchange can be augmented by increasing the flow of air blown over the condenser coil, which can be achieved by increasing the speed of the fan, or by increasing the number of fans. An increase in the speed of the fan, or the number of fans, increases the noise generated by the sound of fan and motor; and flow of air in the HVAC and refrigeration system. The high noise may be uncomfortable for the users of the HVAC and refrigeration system. Various methods are employed to reduce the noise generated in HVAC and refrigeration systems.
One such method or apparatus is the provision of acoustic enclosures. An acoustic enclosure is an enclosed space that is created around the source of the noise. The acoustic enclosure may include walls, and a roof, that are created around the source of the noise. The amount of noise attenuation provided by acoustic enclosures depends on the frequency of the noise, the material used in the construction of walls, and the quality of construction. The construction of an efficient acoustic enclosure entails high cost of manufacturing, and results in an increase in the energy consumption of the fans, which causes the performance of the HVAC and refrigeration system to deteriorate. Further, construction of such an acoustic enclosure complicates the design, installation, operation, and maintenance of the HVAC and refrigeration system.
Another method or apparatus involves the provision of louvers for the HVAC and refrigeration system. Louvers are, typically, frames with horizontal and vertical slats angled to admit air inside the condenser, and also limit the noise. However, the use of louvers has a specific disadvantage which is a drop in the air pressure. This drop in the air pressure results in an increase in the energy consumption of the fans, which causes the performance of the HVAC and refrigeration system to deteriorate.
In light of the foregoing facts, there exists a need for providing a device for attenuating noise in an HVAC and refrigeration systems. The device should be easy to design, should not entail high installation, operation or maintenance costs. Further, the device should enable easy access for the maintenance of HVAC and refrigeration systems. Moreover, the system should not result in a significant drop in the air pressure in such systems.
Embodiments of the invention provide a noise-attenuating device for an HVAC and refrigeration system. The HVAC and refrigeration system includes a condenser and at least one fan system. The noise-attenuating device includes an inner shell with a first outer surface, a first inner surface and a layer of a noise-absorbent material that is enclosed between the first outer surface and the first inner surface. The noise-attenuating device also includes an outer shell that has a second outer surface, a second inner surface, and a layer of the noise-absorbent material that is enclosed between the second outer surface and the second inner surface.
Embodiments of the invention provide a condensing unit for an HVAC and refrigeration system. The condensing unit includes a condenser that includes a condensing coil, at least one fan system that is configured to circulate air across the condenser coil, and a noise-attenuating device. The noise-attenuating device includes a first outer surface, a first inner surface and a layer of a noise-absorbent material that is enclosed between the first outer surface and the first inner surface. The noise-attenuating device is configured to house the at least one fan system. The noise generated by the air circulated by the fan system in the condenser is minimized by using the noise-attenuating device.
The preferred embodiments of the invention will hereinafter be described in conjunction with the appended drawings, provided to illustrate and not to limit the invention, wherein like designations denote like elements, and in which:
Fan 106 is supported by a body 110 of condensing unit 100. During the working of condensing unit 100, the operation of fan 106 causes air to flow across condenser coil 104, and through the passages formed by body 110. The flow of air through the passage generates acoustic sounds. With the increase in the rate of air flow, the intensity of sound increases. This results in an undesirable noise.
A noise-attenuating device is used to minimize the undesirable noise produced in condensing unit 100. In an embodiment of the invention, the noise-attenuating device is a duct. Hereinafter, the ‘noise-attenuating device’ is referred to as the ‘noise-attenuating duct’.
In an embodiment of the invention, the length of inner shell 204 is equal to that of outer shell 202. It will be apparent to a person skilled in the art that the orientation and length of inner shell 204 with respect to outer shell 202 have been mentioned here for illustrative purpose only. They do not, in any way, restrict the scope of the invention, which is equally applicable to other orientations and lengths of inner shell 204 and outer shell 202. In another embodiment of the invention, inner shell 204 is smaller in length than outer shell 202.
Outer shell 202 includes a first outer surface 208, a first inner surface 210, and a layer of a noise-absorbent material 212. First outer surface 208 is parallel to first inner surface 210. In an embodiment of the invention, first outer surface 208 is inclined at an angle to first inner surface 210. The layer of noise-absorbent material 212 is enclosed between first outer surface 208 and first inner surface 210. In an embodiment of the invention, the material of noise-absorbent material 212 is rock wool. In various embodiments of the invention, mineral glass, fiber, and various foams are used as noise-absorbent material 212. It should be noted that any other material with a noise absorbent property can also be used as noise-absorbent material 212.
Inner shell 204 includes a second outer surface 214, a second inner surface 216, and a layer of noise-absorbent material 218. Second outer surface 214 is parallel to second inner surface 216. The layer of noise-absorbent material 218 is enclosed between second outer surface 214 and second inner surface 216. In an embodiment of the invention, the material of noise-absorbent material 218 is rock wool. In various embodiments of the invention, mineral glass, fiber, and various foams are used as noise-absorbent material 218. It should be noted that any other material with a noise absorbent property can also be used as noise-absorbent material 218.
In an embodiment of the invention, first outer surface 208, first inner surface 210, second outer surface 214 and second inner surface 216 are made of a metal alloy such as stainless steel. However, any other metal or a metal alloy, or any other suitable material for enclosing the layers of noise-absorbent materials 212 and 218 can also be used.
In an embodiment of the invention, noise-attenuating duct 200 is used as a suction duct for condensing unit 100 of the HVAC and refrigeration system. In another embodiment of the invention, noise-attenuating duct 200 is used as a discharge duct of condensing unit 100 of the HVAC and refrigeration system. Noise-attenuating duct 200 is installed to minimize the noise generated by the sound of fan 106 and motor 108 and the flow of air inside condensing unit 100.
In an embodiment of the invention, noise-attenuating duct 200 includes inner shell 204 that is placed inside outer shell 202. The orientation of inner shell 204 can be concentric with respect to outer shell 202. Inner shell 204 includes a lower duct 204a and an upper duct 204b. Lower duct 204a houses motor 108. Upper duct 204b is placed above fan 106. The base of upper duct 204b is fitted on the central part of fan 106. Support 206e attaches lower duct 204a to outer shell 202. Similarly, support 206f attaches upper duct 204b to outer shell 202. By using the arrangement described above, the fan system, which includes fan 106 and motor 108, is supported inside noise-attenuating duct 200. As described in conjunction with
In an embodiment of the invention, a suction duct is placed to cover the suction side of fan 106, to minimize the noise generated by fan 106 and motor 108; and the air taken in condensing unit 100. A discharge duct is placed to cover the discharge side of fan 106, to minimize the noise generated by fan 106 and motor 108; and the air coming out of condensing unit 100. The suction duct and the discharge duct together form noise-attenuating duct 200 for condensing unit 100.
The amount of noise attenuation is directly proportional to the length of noise attenuating duct 200. In an embodiment of the invention, the length of noise attenuating duct 200 is increased. The increase in the length results in higher noise attenuation.
Embodiments of the invention offer one or more of the following advantages. The noise-attenuating device is easy in design, and is a cost-effective solution for reduction of noise in HVAC and refrigeration systems. It does not entail high cost of installation, operation or maintenance. Further, the noise-attenuating device enables an easy maintenance of HVAC and refrigeration systems. Moreover, the noise-attenuating device does not result in a significant drop in the air pressure in HVAC and refrigeration systems.
While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art, without departing from the spirit and scope of the invention, as described in the claims.
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/BR07/00362 | 12/27/2007 | WO | 00 | 4/14/2010 |
