U.S. patent application number 11/915799 was filed with the patent office on 2008-07-31 for methods and apparatus for reducing the noise level outputted by oil separator.
This patent application is currently assigned to Carrier Corporation. Invention is credited to Xavier Girod, Michal Grabon, Eric Voluet.
Application Number | 20080179134 11/915799 |
Document ID | / |
Family ID | 35448165 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080179134 |
Kind Code |
A1 |
Grabon; Michal ; et
al. |
July 31, 2008 |
Methods and Apparatus For Reducing the Noise Level Outputted by Oil
Separator
Abstract
A muffling apparatus (100) having a first, muffling segment
(1010) and a second (1020), non-muffling segment is provided for
placement within an oil separator of refrigeration or cooling
system, wherein the apparatus has a non-straight shape and a lumen
defined therein to allow for noise-creating pressure
pulsations/waves to come into contact with absorbing material (120)
of the muffling segment (1010) in order to attenuate the energy of
the pressure waves/pulsations into heat and thus reduce oil
separator vibrations caused thereby.
Inventors: |
Grabon; Michal; (Bressolles,
FR) ; Girod; Xavier; (Montluel, FR) ; Voluet;
Eric; (Saint Denis en Bugey, FR) |
Correspondence
Address: |
MARJAMA MULDOON BLASIAK & SULLIVAN LLP
250 SOUTH CLINTON STREET, SUITE 300
SYRACUSE
NY
13202
US
|
Assignee: |
Carrier Corporation
Farmington
CT
|
Family ID: |
35448165 |
Appl. No.: |
11/915799 |
Filed: |
December 7, 2006 |
PCT Filed: |
December 7, 2006 |
PCT NO: |
PCT/US2005/018827 |
371 Date: |
November 28, 2007 |
Current U.S.
Class: |
181/252 |
Current CPC
Class: |
F25B 43/02 20130101;
F25B 2500/12 20130101 |
Class at
Publication: |
181/252 |
International
Class: |
F01N 1/10 20060101
F01N001/10 |
Claims
1. A method for reducing the noise level outputted by an oil
separator within a refrigeration or cooling system, comprising the
steps of: providing a muffling apparatus having a first segment and
a second segment, wherein the first segment includes an absorbing
material; and placing the muffling apparatus within an internal
area of an oil separator.
2. The method of claim 1, wherein the muffling apparatus has a
non-straight overall shape.
3. The method of claim 2, wherein the non-straight overall shape is
selected from the group consisting of a bent shape and a curved
shape.
4. The method of claim 2, wherein the first segment has a
substantially straight shape and the second segment has a
substantially curved shape.
5. The method of claim 1, wherein the first segment has a first
end, a second end and a lumen defined therebetween, and wherein at
least a portion of the absorbing material is in direct fluid
communication with the lumen.
6. The method of claim 5, wherein at least a portion of the
absorbing material is in direct fluid communication with the lumen
via a plurality of openings.
7. The method of claim 1, wherein the step of placing the muffling
apparatus within the internal area of the oil separator is
accomplished by attaching the muffling apparatus to the internal
area of the oil separator.
8. The method of claim 1, wherein the muffling apparatus is
attached to a first end of a support element, and wherein a second
end of the support element is attached to the internal area of the
oil separator.
9. The method of claim 1, wherein the absorbing material is a
fiberglass material.
10. A muffling apparatus for placement within an internal area of
an oil separator, the muffling apparatus comprising: a first
segment having a first end, a second end and a lumen therebetween,
wherein the first segment is at least partially constructed of an
absorbing material; and a second segment connected to the first
segment.
11. The muffling apparatus of claim 10, wherein at least a portion
of the absorbing material is in direct fluid communication with the
lumen.
12. The muffling apparatus of claim 10, wherein the first segment
is comprised of: an external shell; an internal layer formed at
least partially of the absorbing material, wherein the internal
layer is surrounded by the external shell; and an internal shell,
wherein the internal shell surrounds the lumen.
13. The muffling apparatus of claim 12, wherein the internal layer
has a plurality of openings defined therein to enable direct fluid
communication between the absorbing material and the lumen.
14. The muffling apparatus of claim 10, wherein the absorbing
material is a fiberglass material.
15. The muffling apparatus of claim 12, wherein each of the
external shell and the internal shell is made of a sheet metal
material.
16. The muffling apparatus of claim 11, wherein the muffling
apparatus has a non-straight overall shape.
17. The muffling apparatus of claim 16, wherein the non-straight
overall shape is selected from the group consisting of a bent shape
and a curved shape.
18. The muffling apparatus of claim 16, wherein the first segment
has a substantially straight shape and the second segment has a
substantially curved shape
19. The muffling apparatus of claim 11, wherein the muffling
apparatus is attached to a first end of a support element, and
wherein a second end of the support element is attached to the
internal area of the oil separator.
Description
FIELD OF THE INVENTION
[0001] This invention relates to oil separators for use in
refrigeration and cooling systems, and, in particular, to methods
and apparatus for reducing the noise levels outputted by an oil
separator that is located within a refrigeration or cooling
system.
BACKGROUND OF THE INVENTION
[0002] As illustrated by FIG. 1, a water cooled chiller type
refrigeration system 10 using a screw compressor 20 typically
includes a condenser 30, a cooler 40, an oil separator 50, a
condenser fan 60 and one or more expansion devices 70. The
compressor 20 requires oil for lubrication, wherein the oil is
typically entrained in a refrigerant. The combined oil and
refrigerant mixture is carried through a compression cycle and
discharged into the oil separator 50, where the oil must be removed
from the refrigerant to allow for proper operation of the cooler
40. From the oil separator 50, the clean refrigerant flows to the
condenser 30 and the separated oil is returned to the compressor
10.
[0003] Most known oil separators, such as those described in U.S.
Pat. No. 5,704,215 to Lord et al. (the entirety of which is
incorporated by reference herein), perform this separation function
well. However, it has been observed that high noise levels are
often generated in the vicinity of an oil separator 50 within a
refrigeration system, such as the system 100 illustrated in FIG. 1.
Without wishing to be bound by theory, it is believed that this is
caused by high level pressure waves/pulsations (i.e., 250 Hz or
above) emanating from the compressor 20 that are transferred to the
oil separator 50, which acts like a resonant cavity and thus is
excited by the compressor pulsations. This excitement causes high
vibration levels at the surface of the oil separator 50, and that,
in turn, translates into high noise levels outputted by the oil
separator. These excess noise levels can be distracting and
bothersome, or, even worse, can be damaging to the hearing of those
working around the oil separator 50 and/or can be in violation of
applicable noise ordinances.
[0004] Previous efforts by those in the art to reduce the high
noise levels produced by an oil separator 50 have focused on
placing noise reduction equipment or devices between the oil
separator and the compressor 20. Often, however, such equipment is
subjected to high pressure differentials between the compressor
discharge within the equipment and the atmosphere outside of the
equipment. In such instances, the noise reduction equipment
functions, in essence, as a pressure vessel, thus implicating
strict design rules, certifications, and by consequence, added
costs. Moreover, the added noise reduction equipment causes the
refrigeration/cooling system to occupy a larger overall footprint,
which is suboptimal and can even outweigh any beneficial noise
reduction that actually is achieved through use of the
equipment.
[0005] Therefore, a need exists for methods and apparatus to reduce
the noise output of an oil separator without interfering with the
functioning of the oil separator or any other equipment utilized in
connection with the refrigeration system, and wherein such methods
and apparatus would not be plagued by any of the various drawbacks
associated with muffling apparatus known in the art.
SUMMARY OF THE INVENTION
[0006] These and other needs are met by the present invention,
which provides a muffling apparatus and methods for using the
muffling apparatus to reduce the noise level output of an oil
separator within a refrigeration or cooling system. The muffling
apparatus of the present invention has a first, muffling segment
and a second, non-muffling segment and is placed within an internal
area of an oil separator.
[0007] The muffling segment of the muffling apparatus is at least
partially formed of an absorbing material. The absorbing material
is effective to attenuate the energy of pressure waves/pulsations
from the compressor into heat, thus reducing the resultant
vibrations of (and, in turn, noise levels outputted from) the oil
separator caused by energy from the waves/pulsations. The muffling
segment is comprised of a tubular body that includes an external
shell, wherein the external shell surrounds an internal layer and
wherein the internal layer surrounds an internal shell. The
muffling segment also has a first end, a second end and a lumen
therebetween, wherein the lumen is surrounded by the internal shell
of the muffling segment.
[0008] In an exemplary aspect of the present invention, the
internal layer of the muffling segment of the muffling apparatus is
made of the absorbing material, and the internal shell has a
plurality of perforations/openings defined therein. Each opening
provides a direct fluid/air pathway from the lumen to the internal
layer of absorbing material. The purpose of the openings is to
enable the pressure waves/pulsations that propagate through the
lumen of the muffling segment to come into contact with the
internal layer of absorbing material, thus enabling the absorbing
material to attenuate the pressure waves/pulsations.
[0009] In another exemplary aspect of the present invention, the
non-muffling segment of the muffling apparatus has a tubular body,
wherein the first end of the non-muffling segment is connected to
the second end of the muffling segment and the second end of the
non-muffling segment is connected to an internal area of an oil
separator.
[0010] In yet another exemplary aspect of the present invention,
the muffling apparatus has a non-straight shape, such as a bent
shape or a curved shape, wherein the bent or curved portion(s) of
the non-straight muffling apparatus are part of the non-muffling
segment.
[0011] Still other aspects, embodiments and advantages of the
present invention are discussed in detail below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0012] For a fuller understanding of the nature and desired objects
of the present invention, reference is made to the following
detailed description taken in conjunction with the accompanying
figures, wherein like reference characters denote corresponding
parts throughout the views, and in which:
[0013] FIG. 1 is a schematic view of a known exemplary arrangement
of a refrigeration/cooling system utilizing an oil separator.
[0014] FIG. 2 is a perspective view of an exemplary embodiment of
an oil separator muffling apparatus in accordance with the present
invention;
[0015] FIG. 3 is a side, cross-sectional view of the muffling
apparatus of FIG. 2 taken along line 3-3 of FIG. 2; and
[0016] FIG. 4 is a perspective view, with partial cut away, of an
exemplary oil separator wherein the muffling apparatus of FIGS. 2
and 3 has been placed within an internal area thereof.
DETAILED DESCRIPTION
[0017] The present invention provides a muffling apparatus and
methods of using the apparatus to reduce the noise level output
produced by an oil separator of a refrigeration or cooling system,
such as a water-cooled chiller type refrigeration system. In use,
the muffling apparatus of the present invention is placed within an
oil separator in order to attenuate pressure waves/pulsations that
emanate from the compressor of the refrigeration system. As
discussed above, such pressure waves/pulsations are believed to be
responsible for creating vibrational forces that cause the oil
separator surface to vibrate and, in turn, to disadvantageously
generate high noise levels in its vicinity.
[0018] Attenuation occurs during use of the muffling apparatus of
the present invention because the pressure waves/pulsations come
into contact with an absorbing material located within a muffling
segment of the muffling apparatus. The absorbing material
attenuates the energy of the pressure waves/pulsations into heat
and thus reduces the resultant vibrations of (and, in turn, noise
levels outputted from) the oil separator that are caused by energy
from the pressure waves/pulsations.
[0019] The muffling apparatus of the present invention has many
benefits. In particular, not only does the muffling apparatus
successfully reduce oil separator noise levels, but it does so
while being sited within an oil separator, thus not requiring the
refrigeration/cooling system to occupy added space and not exposing
the muffling apparatus to high pressure differentials. The design
of the muffling apparatus also provides costs savings, as will be
discussed in detail below.
[0020] FIGS. 2 and 3 depict an exemplary oil separator muffling
apparatus 100 in accordance with the present invention. The
muffling apparatus 100 has at least two segments, wherein each
segment serves a different purpose in accordance with the present
invention and is made of different materials or material
combinations than the other segment(s). The segments are connected
to each other as is known in the art, e.g., by welding, brazing
and/or through the use of rivets.
[0021] As is currently preferred, and as is best shown in FIG. 3, a
muffling apparatus 100 of the present invention has a first,
muffling segment 1010 and a second, non-muffling segment 1020. The
muffling segment 1010 has a tubular body comprised of an external
shell 110 that surrounds an internal layer 120, wherein the
internal layer has an internal shell 130--that is, the external
shell and the internal shell "sandwich" the internal layer.
Although it is currently preferred for the number and arrangement
of the shells 110, 130 and the internal layer 120 of the muffling
segment 1010 to be as shown in FIGS. 2 and 3, it is also within the
scope of the present invention for the muffling segment to be
comprised of more or fewer layers and/or more or fewer shells than
are depicted in the Figures, and/or for the layer(s) and/or the
shell(s) to have a different arrangement than that which is
shown.
[0022] The muffling segment 1010 has a first end 140, a second end
150 and a lumen 160 therebetween, wherein the lumen is surrounded
by the internal shell 130. The second end 150 of the muffling
segment 1010 is adapted for connection to a first end 1100 of the
non-muffling segment 1020 by techniques known in the art, e.g.,
welding, brazing and/or through the use of rivets.
[0023] As noted above, the purpose of the muffling segment 1010 is
to reduce the noise level output of an oil separator in which the
muffling apparatus 100 is placed. To enable that to occur, at least
one of the external shell 110, the internal layer 120 and the
internal shell 130 of the muffling segment 1010 should be made, at
least partially, of a material that will absorb the energy from
pressure waves (that emanate from the compressor and are
transferred to the oil separator) and dissipate/attenuate that
energy into absorbable heat. According to a currently preferred
embodiment of the present invention, the internal layer 120 of the
muffling segment 1010 is made of such an absorbing material. The
specific choice of the absorbing material can vary according to
several factors, including but not limited to cost, dumping
characteristics, availability and designer preference. According to
an exemplary embodiment of the present invention, the absorbing
material is a fiberglass material. A currently preferred fiberglass
material is comprised of glass fibers with a phenolic resin,
wherein the material has a density in the range of about 86
kg/m.sup.3 to about 105 kg/m.sup.3 and a maximum temperature of
about 177.degree. C.
[0024] The material(s) from which the external shell 110 and the
internal shell 130 of the muffling segment 1010 are constructed
should be strong and durable, yet inexpensive. The external shell
110 and the internal shell 130 can be constructed of different or
identical materials; however, according to an exemplary embodiment
of the present invention, both the external shell 110 and the
internal shell 130 are constructed of a sheet metal material. A
currently preferred sheet metal material is steel, but other
metal-based materials can be utilized as well.
[0025] As shown in FIGS. 2 and 3, the internal shell 130 of the
muffling segment 1010 has a plurality of perforations or openings
170 defined therein. Each opening 170 provides direct fluid
communication between the lumen 160 and the internal layer 120 of
absorbing material. The purpose of the openings 170 is to enable
the pressure waves/pulsations that are propagating/passing through
the lumen 160 of the muffling segment 1010 to come into contact
with the internal layer 120 of absorbing material, thus enabling
the absorbing material to attenuate the pressure
waves/pulsations.
[0026] The size, shape, number and spacing interval of the openings
170 can vary depending on several factors, including, but not
limited to, the frequency of the pressure waves/pulsations that are
expected to be encountered. According to a currently preferred
embodiment of the present invention, openings 170 are defined in a
range of about 10% to about 50% of the overall surface area of the
internal shell 130. Moreover, although the openings 170 can have
any shape and any spacing interval, it is currently preferred for
the openings to be substantially round and spaced apart from each
other at substantially identical distances, as best shown in FIG.
3.
[0027] The non-muffling segment 1020 of the muffling apparatus 100
also has a tubular body, and has first and second ends 1100, 1200.
The first end 1100 of the non-muffling segment is connected to the
second end 150 of the muffling segment 1010, and the second end
1200 of the muffling segment is connected to an internal area 510
of an oil separator 500, as shown in FIG. 4. Such connections are
made as is generally known in the art, e.g., via welding, brazing
and/or through the use of rivets.
[0028] Although the non-muffling segment 1020 of the muffling
apparatus 100 can have more than one layer and can be made of more
than one material, it is currently preferred to form the
non-muffling segment of one layer and one material, wherein
suitable materials include sheet metal materials such as steel.
There are several advantages of forming the non-muffling segment
1020 of the muffling apparatus entirely from a metal-based
material, including, but not limited to, cost savings and design
flexibility. The cost savings occurs because sheet metal material
is less expensive to purchase as compared to the absorbing material
used in the muffling segment 1010. Also, there is design
flexibility because one can purchase many different pre-formed
shapes and sizes of the sheet metal material from which the
non-muffling segment 1020 is formed.
[0029] The size and shape of muffling apparatus 100 also can vary;
however, it is currently preferred for muffling apparatus 100 to
have a non-straight overall shape. For example, FIGS. 2 and 3
depict a muffling apparatus that has a curved shape. The
non-straight shape of muffling apparatus 100 is preferred because
it enables the apparatus to have a larger size (as compared to an
apparatus with a straight shape) while still fitting within the
space confines of an oil separator. That allows for a longer lumen
160 to be defined between the first and second ends 140, 150 of a
the muffling segment 1010, thus providing added opportunities for
pressure waves/pulsations to come into contact with the internal
layer 120 via openings 170.
[0030] As shown in FIGS. 2 and 3, and as is currently preferred,
muffling segment 1010 of muffling apparatus 100 has a substantially
straight shape and non-muffling segment 1020 has a curved shape.
Such an arrangement is advantageous because a cost savings is
achieved by not forming the muffling apparatus entirely of the
muffling segment materials, yet the muffling apparatus is still
capable of providing significant noise reduction, as will be
discussed in more detail below.
[0031] Optionally, and as shown in the Figures, support element 600
is attached (e.g., by welding) to the first end 150 of the muffling
segment 1010 and to the internal area 510 of the oil separator 500.
The presence of the support element 600 provides added support to
muffling apparatus 100 by bearing the weight of muffling segment
1010. Support element 600 can be made of a variety of materials,
including, but not limited, to one or more metal-based materials
(e.g., steel).
[0032] The size of the muffling apparatus 100 can vary depending on
several factors, most notably the size of the oil separator in
which the muffling apparatus is installed. It is currently
preferred for the size of the muffling apparatus 100 to vary
proportionally with the size of the oil separator. For example, the
muffling apparatus 100 will have a different predetermined size in
order to fit within a 14 inch oil separator than it would to fit
within a 16 inch oil separator or an 18 inch oil separator, wherein
the size of the muffling apparatus for a 16 inch oil separator
generally will be approximately 16/14 times the size of the
muffling apparatus for a 14 inch oil separator and approximately
16/18 times the size of the muffling apparatus for an 18 inch oil
separator.
[0033] According to an exemplary embodiment of the present
invention in which the muffling apparatus 100 is placed in a 14
inch oil separator, the effective height, H (see FIG. 3), occupied
by the muffling apparatus is in the range of about 7.5 inches to
about 9.5 inches, with an effective height of about 8.5 inches
being currently preferred, and the effective length, L (see FIG. 3)
occupied by the muffling apparatus is in the range of about 11
inches to about 13.5 inches, with an effective height of about 13.2
inches being currently preferred. For placement within a 16 inch
oil separator, these measurements would be approximately 16/14
times those for the 14 inch oil separator, and for placement within
an 18 inch oil separator, they would be approximately 18/14 times
those for the 14 inch oil separator.
[0034] The length of muffling segment 1010 also can vary according
to several factors, including the frequency of the pressure waves
expected to the encountered within the oil separator. For example,
the length of muffling segment 1010 can be comparatively greater
when the frequency of the pressure waves is expected to be about
2000 Hz versus 125 Hz. According to an exemplary embodiment of the
present invention in which muffling apparatus 100 is placed within
a 14 inch oil separator, the length of the muffling segment 1010 is
about 4.5 inches to about 6.5 inches, wherein a length of about 6
inches is currently preferred. Stated differently, the length of
muffling segment 1010 generally comprises about 30% to about 60% of
the overall length, L, of the muffling apparatus 100. For placement
within a 16 inch and 18 inch oil separators, the length
measurements would be approximately 16/14 times greater and 18/14
times greater, respectively.
[0035] Experiments were conducted to assess the noise reduction
efficacy of a muffling apparatus 100 of the present invention. The
experiments were performed in accordance with the guidelines of
International Organization for Standardization (ISO 9614). The
results of the experiments are shown in Table I below:
TABLE-US-00001 TABLE I Pressure Wave (octave in Hz) 125 250 500
1000 2000 4000 Acoustic change (dB) due to -1 -12 -6 -1 -7 -12
presence of muffling apparatus Global dBA = -4
[0036] To accumulate the test results in Table I, a refrigeration
system was first operated such that its oil separator encountered
six different pressure wave frequencies (125 Hz, 250 Hz, 500 Hz,
1000 Hz, 2000 Hz and 4000 Hz) emanating from its compressor,
wherein the noise level outputted by the oil separator in response
to each of these pressure wave levels was measured and recorded. A
muffling apparatus 100 of the type shown in FIGS. 2 and 3 was then
installed within the oil separator and the testing conditions were
repeated to gather comparable data.
[0037] The experimental results in Table I demonstrate that there
was an acoustic reduction at each pressure wave frequency level due
to the presence of the muffling apparatus 100, wherein the acoustic
reduction was calculated as the difference between the acoustic
level at the oil separator without a muffling apparatus versus the
acoustic level at the same oil separator with a muffling apparatus
of the present invention installed within an internal area thereof.
Therefore, the -12 dB measurement at 250 Hz indicates that the
noise level measurement taken after the muffling apparatus 100 was
installed within the oil separator was 12 dB less than the
measurement taken when the same oil separator was not equipped with
the muffling apparatus. The Global dBA of -4 dBA also supports that
there was an acoustic reduction, and that the dominant frequency
band of the pressure waves/pulsations was in the range of about
500-1000 Hz.
[0038] The results in Table I are very favorable. In particular,
noise reduction levels were observed for each of the six selected
pressure wave frequency bands. This is important because different
compressors operate at different dominant pressure output levels,
and thus would produce different Global dBA measurements. Moreover,
noise reduction occurred despite the fact that the muffling
apparatus was only partially formed of a muffling segment 1010.
This signifies that by forming the muffling apparatus from a
muffling segment 1010 and a non-muffling segment 1020, one can
achieve noise reduction while enjoying cost savings and design
flexibility.
[0039] Thus, a muffling apparatus 100 of the type shown in FIGS. 2
and 3 can be installed in an oil separator with confidence that the
noise level reduction will be at least 1 dB, with a noise reduction
level of up to 12 dB being possible as well depending on the
dominant frequency band of the pressure/wave pulsations emanating
from the compressor. These are significant noise reduction levels,
especially when considering the effects of exposure to the reduced
noise level over the lifetime of the refrigeration system in which
the oil separator is located. Moreover, a noise reduction level of
between 1 dB and 12 dB will be even more significant if, as is
commonly the case, multiple refrigeration systems that include oil
separators are installed in close proximity.
[0040] Although the present invention has been described herein
with reference to details of currently preferred embodiments, it is
not intended that such details be regarded as limiting the scope of
the invention, except as and to the extent that they are included
in the following claims--that is, the foregoing description of the
present invention is merely illustrative, and it should be
understood that variations and modifications can be effected
without departing from the scope or spirit of the invention as set
forth in the following claims. Moreover, any document(s) mentioned
herein are incorporated by reference in their entirety, as are any
other documents that are referenced within the document(s)
mentioned herein.
* * * * *