U.S. patent application number 13/505216 was filed with the patent office on 2012-10-25 for cooling system for reciprocating compressors and a reciprocating compressor.
This patent application is currently assigned to UNIVERSIDADE FEDERAL DE SANTA CATARINA - UFSC. Invention is credited to Cesar Jose Deschamps, Fernando Antonio Ribas Junior, Jader Riso Barbosa Junior, Rodrigo Kremer, Dietmar Erich Bernhard Lilie, Joao Ernesto Schreiner.
Application Number | 20120267075 13/505216 |
Document ID | / |
Family ID | 43068041 |
Filed Date | 2012-10-25 |
United States Patent
Application |
20120267075 |
Kind Code |
A1 |
Kremer; Rodrigo ; et
al. |
October 25, 2012 |
COOLING SYSTEM FOR RECIPROCATING COMPRESSORS AND A RECIPROCATING
COMPRESSOR
Abstract
Cooling system for reciprocating compressors comprising an
atomizing nozzle (1) that supplies an atomized lubricating fluid
inside the compressor cylinder (2), a heat exchanger (6) intended
for cooling the lubricating fluid to be atomized at the nozzle (1),
a fluid separator (5) for separating a mixture of cooling fluid and
lubricating fluid and directing the lubricating fluid back from the
system, and a blocking element (7) arranged between the atomizing
nozzle (1) and the heat exchanger (6) to prevent the buildup of
lubricating fluid in the cylinder. Reciprocating compressor having
the cooling system as described.
Inventors: |
Kremer; Rodrigo; (Blumenau,
BR) ; Lilie; Dietmar Erich Bernhard; (Joinville,
BR) ; Junior; Fernando Antonio Ribas; (Joinville,
BR) ; Deschamps; Cesar Jose; (Florianopolis, BR)
; Schreiner; Joao Ernesto; (Florianopolis, BR) ;
Junior; Jader Riso Barbosa; (Florianopolis, BR) |
Assignee: |
UNIVERSIDADE FEDERAL DE SANTA
CATARINA - UFSC
Florianopolis
SC
WHIRLPOOL S.A.
Sao Paulo
SP
|
Family ID: |
43068041 |
Appl. No.: |
13/505216 |
Filed: |
September 20, 2010 |
PCT Filed: |
September 20, 2010 |
PCT NO: |
PCT/BR2010/000317 |
371 Date: |
July 13, 2012 |
Current U.S.
Class: |
165/104.19 |
Current CPC
Class: |
F04B 39/062 20130101;
F04B 39/0269 20130101 |
Class at
Publication: |
165/104.19 |
International
Class: |
F28D 15/00 20060101
F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 30, 2009 |
BR |
PI0904162-1 |
Claims
1. A cooling system for an alternating-type compressor (10), the
compressor comprising a housing (11) and a compressor chamber (2)
inside the housing (11), CHARACTERIZED in that it comprises: an
atomizing nozzle (1), which supplies an atomized lubricating fluid
inside the compressor cylinder; a heat exchanger (6) designed to
cool the lubricating fluid to be atomized at the nozzle (1); a
fluid separator (5) to separate a mixture of refrigerating fluid
and lubricating fluid and direct the lubricating fluid back from
the system; and a blocking element (7) to prevent the build-up of
lubricating fluid in the cylinder.
2. A cooling system, according to claim 1, CHARACTERIZED in that
the blocking element (7) is arranged between the atomizing nozzle
(1) and the heat exchanger (6).
3. A cooling system, according to claim 1, CHARACTERIZED in that
the blocking element (7) is integrated to the injecting nozzle
(1).
4. A cooling system, according to any of claims 1 to 3,
CHARACTERIZED in that the blocking element (7) is a blocking
valve.
5. A cooling system, according to any of claims 1 to 3,
CHARACTERIZED in that the blocking element is an electric blocking
element.
6. A cooling system, according to any of claims 1 to 3,
CHARACTERIZED in that the blocking element is an electronic
blocking element.
7. A cooling system, according to any of claims 1 to 6,
CHARACTERIZED in that the blocking element (7) is arranged inside
the housing (11).
8. A cooling system, according to any of claims 1 to 7,
CHARACTERIZED in that the fluid separator (5) receives the mixture
of cooling fluid and lubricating fluid discharged from the
compression chamber (2) and directs the lubricating fluid back to
the heat exchanger (6).
9. A cooling system, according to any of claims 1 to 7,
CHARACTERIZED in that the fluid separator (5) receives the mixture
of cooling fluid and lubricating fluid from the heat exchanger (6)
and directs the lubricating fluid back to the blocking element
(7).
10. A cooling system, according to any of claims 1 to 7,
CHARACTERIZED in that the lubricating fluid separator (5) and the
heat exchanger (6) comprise a single component.
11. A cooling system, according to claim 9, CHARACTERIZED in that
the single component is arranged inside the housing (11).
12. A cooling system, according to any of claims 1 to 8,
CHARACTERIZED in that the lubricating fluid separator (5) is
arranged inside the housing (11).
13. A cooling system, according to any of claims 1 to 8,
CHARACTERIZED in that the heat exchanger (6) is arranged inside the
housing (11).
14. A cooling system, according to any of claims 1 to 8,
CHARACTERIZED in that the lubricating fluid separator (5) and the
heat exchanger (6) are arranged inside the housing (11).
15. A cooling system, according to claim 13 or 14, CHARACTERIZED in
that the heat exchanger is arranged in the space in the housing
(11) intended for storing the lubricating fluid, the heat exchanger
(6) being submerged in the lubricating fluid.
16. A cooling system, according to any of claims 1 to 15,
CHARACTERIZED in that the injecting nozzle (1) dispensing end
touches lightly the sidewall of the compressor (10) cylinder
block.
17. A cooling system, according to any of claims 1 to 15,
CHARACTERIZED in that the injecting nozzle (1) dispensing end is
arranged on the compressor (10) valve plate.
18. An alternating compressor (10), CHARACTERIZED in that it is of
the type comprising a cooling system as defined in any of claims 1
to 17.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a cooling system for
compressors, and, more particularly, to a cooling system for
alternating compressors. The present invention also relates to an
alternating compressor having a cooling system.
BACKGROUND OF THE INVENTION
[0002] It is the function of a compressor to increase the pressure
of a certain fluid volume to a pressure required for carrying out a
certain work. For the refrigeration industry, the more used
compressors are the alternating-type compressors. It is the
function of these compressors to suck a cooling fluid at a low
pressure and compress it towards the condenser at a high pressure
and high temperature.
[0003] Alternating compressors are those wherein a certain driving
mechanism provides an alternating motion to a piston inside a
cylinder (such a mechanism may comprise, for example, a rod-lever
system). Thus, the piston moves alternately inside a cylinder, and
suction and discharge valves are provided to allow the suction and
discharge of the cooling fluid.
[0004] The cooling of the compressor has a significant impact on
the thermodynamic performance thereof. A great part of a compressor
inefficiency is associated with the overheating of the cooling
fluid that takes place along the suction path (located between the
suction conveyer and the compressing cylinder). Another part,
equally important, of a compressor inefficiency is associated with
the heating of the cooling fluid during its compression.
[0005] The heating of the coolant in the suction path is caused by
the heat exchanges with the compressor components that are at
higher temperatures than that of the cooling fluid. On the other
hand, the heating of the cooling fluid in the process of
compression takes place mainly due to the work carried out by the
piston, and also the heat transfer through the cylinder and piston
walls at the beginning of the compression.
[0006] The overheating in the suction path reduces the volumetric
efficiency of the compressor, since it increases the particular
volume of the cooling fluid admitted into the compression chamber.
In addition, the higher temperature at the start of the compression
process also implies a major particular compression work, reducing
the energy efficiency of the compressor.
[0007] In addition to the inefficiencies caused by the heating of
the coolant during the compression, the coolant heated during its
compression is a major source of heat for the compressor, and it is
the main cause of the heating of the compressor other components,
which, as a consequence, will heat the coolant along the suction
path.
[0008] In view of the foregoing, it becomes apparent that the
cooling of the coolant during the compression process thereof would
have a positive impact on the compression efficiency and, as a
consequence, would allow the decrease in the losses due to the
overheating of the coolant during suction.
OBJECTS OF THE INVENTION
[0009] In view of the foregoing, it is one of the objects of the
present invention to provide a cooling system for alternating
compressors that is able to draw heat from the compressor cooling
fluid during the compression process, decreasing its temperature
and its specific volume.
[0010] It is another object of the present invention to provide a
cooling system for alternating compressors that allows for a
decrease in the temperature levels of the compressor during its
operation.
[0011] It is still another object of the present invention to
provide a cooling system for compressors that improves the
volumetric efficiency and the energy efficiency of the
compressor.
SUMMARY OF THE INVENTION
[0012] The present invention achieves these and other objects
through a cooling system for an alternating-type compressor
comprising a housing and a compression chamber inside the housing,
the system comprising: [0013] an atomizing nozzle, which provides
an atomized lubricating fluid inside the compressor cylinder;
[0014] a heat exchanger designed to cool the lubricating fluid that
will be atomized at the nozzle; [0015] a fluid separator to
separate a mixture of cooling fluid and lubricating fluid and
direct the lubricating fluid back from the system; and [0016] a
blocking element for preventing the buildup of lubricating fluid
inside the cylinder.
[0017] The blocking element may be arranged, for example, between
the atomizing nozzle and the heat exchanger, or even integrated
into the atomizing nozzle.
[0018] In the preferred embodiment of the present invention, the
blocking element is a blocking valve that remains open during the
compressor operation and is closed after it is turned off. However,
the blocking element may comprise other types of device, such as,
for example, an electric blocking element or an electronic blocking
element.
[0019] In addition, the blocking element may be arranged inside the
compressor housing, very close to the compressor cylinder.
[0020] In the preferred embodiment of the present invention, the
fluid separator receives a mixture of cooling fluid and lubricating
fluid discharged from the compression chamber and directs the
lubricating fluid back to the heat exchanger.
[0021] However, in one embodiment of the present invention, the
lubricating fluid separator and the heat exchanger may be in a
mutually inverted position, wherein the fluid separator receives
the mixture of cooling fluid and lubricating fluid from the heat
exchanger.
[0022] Also, in yet another embodiment of the present invention,
the lubricating fluid separator and the heat exchanger may comprise
a single component, and such component may be arranged inside or
outside the compressor housing.
[0023] In one embodiment of the present invention, the lubricating
fluid separator and the heat exchanger are arranged outside the
housing.
[0024] In yet other embodiments, the lubricating fluid separator
and the heat exchanger may be arranged inside the housing, making
the assembly more compact.
[0025] The injecting nozzle may be arranged such that its
dispensing end touches lightly the side wall of the compressor
cylinder block, or such that the injecting nozzle dispensing end is
arranged in the compressor valve plate.
BRIEF DESCRIPTION OF THE DRAWINGS
[0026] The figures show:
[0027] FIG. 1 illustrates a first embodiment of refrigerating
system of the present invention;
[0028] FIG. 2 illustrates a second embodiment of the refrigerating
system of the present invention;
[0029] FIG. 3 illustrates a third embodiment of the refrigerating
system of the present invention;
[0030] FIG. 4 illustrates a fourth embodiment of the refrigerating
system of the present invention;
[0031] FIG. 5 illustrates a fifth embodiment of the refrigerating
system of the present invention; and
[0032] FIG. 6 illustrates a sixth embodiment of the refrigerating
system of the present invention.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The present invention will be described in further detail
below based on the performance examples shown in the drawings. The
figures illustrate six alternative embodiments of the refrigerating
system of the present invention.
[0034] In the embodiments illustrated in the figures, the
refrigerating system is applied to an alternating compressor 10 of
the type comprising a housing 11 and a compression chamber 2
arranged inside the housing. The main components of compressor 10
are those of a conventional alternating compressor known by those
skilled in the art, and, therefore, the operation and specific
construction of these components will be described as long as such
description is necessary to the understanding of the cooling system
of the present invention. While the drawings show a compressor
wherein the piston driving mechanism is of the rod-lever type, any
person skilled in the art will understand that another device that
provides the piston alternating motion may be also employed within
the inventive concept of the present invention.
[0035] The cooling system of the present invention contemplates the
atomization of the lubricating fluid inside the cylinder, and this
fluid must be atomized at the lowest possible temperature.
[0036] Thus, the system of the present invention primarily
comprises an atomizing nozzle 1, which supplies an atomized
lubricating fluid inside the compressor cylinder, a heat exchanger
6 designed to cool the lubricating fluid, which will be atomized at
nozzle 1, a lubricating fluid separator 5, which receives the
mixture of cooling fluid and lubricating fluid discharged from the
compressor and directs the separated lubricating fluid back to the
heat exchanger, and a blocking element 7, the function of which is
to prevent the build-up of lubricating fluid in the cylinder when
the compressor is turned off.
[0037] In the preferred embodiment of the present invention,
blocking element 7 is a blocking valve, however, another suitable
type of blocking element could be equally utilized, such as, for
example, a mechanically or electric-mechanically driven blocking
element, an electrically driven blocking system, an electronically
driven blocking system or a magnetically driven blocking
element.
[0038] In that direction, an electrically or electronically driven
blocking element may be designed so as to use the information from
the compressor electric engine, such as, for example, a driving
current. Similarly, in compressors that apply on board
electronics--as in variable speed compressors--the electronics
required to control the blocking element may be integrated with the
compressor electronics.
[0039] The blocking element of the system of the present invention
may be located, for example, between the atomizing nozzle 1 and
heat exchanger 6, or it may be integrated into injecting nozzle 1.
In the latter case, the atomizing nozzle itself, with an integrated
blocking element, could block the flow when necessary.
[0040] Further, while in FIGS. 1 to 6 the blocking element is shown
as a part external to the compressor housing 11, such element could
be inside this housing. This particularly advantageous possibility
allows the blocking element to be arranged very close to the
compressor cylinder, thus reducing the oil volume between the
cylinder and the blocking element. Since, when turning off the
compressor, the oil contained in this volume ends up going to the
cylinder, this reduction in the volume has a quite positive
impact.
[0041] The system of the present invention allows for a decrease in
the overall heating of the compressor and achieves a decrease in
the temperature of the coolant during the entire compression
cycle.
[0042] Thus, in the first embodiment of the present invention,
atomizing nozzle 1, connected to a lubricating fluid feed line 8,
is positioned inside housing 11, with its hole (or its dispensing
end) touching lightly the cylinder inner wall, such that the
lubricating fluid is atomized inside the cylinder in the period of
the compression cycle during which the piston is not covering the
hole.
[0043] As the atomized lubricating fluid droplets exhibit a large
surface area, the potential for heat exchange with the cooling
fluid during compression is significant, reducing the increase in
the coolant vapor temperature during its compression.
[0044] To assure the atomization of the lubricating fluid at the
lowest possible temperature, atomizing nozzle 1 is connected to
heat exchanger 6, which, in the embodiment illustrated in FIG. 1,
is located outside housing 11.
[0045] Between atomizing nozzle 1 and heat exchanger 6 is a
blocking element 7, such as, for example, a blocking valve 7, which
remains open during the compressor operation and is closed after
the same is turned off.
[0046] After reaching the discharge pressure, the lubricating
fluid, along with the cooling fluid, is discharged from the
compression chamber through a discharge valve 3 and follows a
discharge line 4.
[0047] The lubricating fluid separator 5 is connected to discharge
line 4 and to heat exchanger 6, so that the lubricating fluid from
the discharge line is separated from the cooling fluid and directed
towards the heat exchanger, starting the cycle again.
[0048] FIG. 2 provides one embodiment similar to that of FIG. 1,
the lubricating fluid separator 5 being arranged inside housing 11
of compressor 10. Thus, in this embodiment, the cooling fluid,
along with the lubricating fluid, is discharged from the
compression chamber through discharge valve 3, following discharge
line 4, lubricating fluid separator 5 being positioned in the inner
discharge line of compressor 10. This embodiment, apart from
providing a more compact structure than that illustrated in FIG. 1,
causes separator 5 to act as a pressure attenuator, filtering the
pressure pulses generated during the coolant discharge. Also, since
heat exchanger 6 remains outside the compressor, the heat exchange
efficiency is preserved.
[0049] FIG. 3 depicts a third alternative embodiment of the present
invention, wherein both lubricating oil separator 5 and heat
exchanger 6 are located inside housing 11 of compressor 10.
[0050] In this embodiment, the lubricating fluid feed line 8 and
blocking element 7 also remain inside compressor 10, being arranged
inside housing 11. It should be noted that this embodiment allows
for compressor construction extremely compact.
[0051] In the embodiment illustrated in FIG. 3, heat exchanger 6 is
submerged in the compressor crankcase oil. This configuration
increases the oil temperature in the crankcase, which may have an
additional effect on the increase of the compressor efficiency. The
reason for this is that, with the injection of cold oil droplets in
the cylinder and the subsequent cooling of the compressed gas, the
expected result is an overall reduction in the compressor
temperature levels. This reduction in temperature will cause an
increase in the oil viscosity, increasing the mechanical losses.
Upon placing the heat exchanger in the oil, part of this problem is
compensated for, by supplying part of the heat directly removed
from the compression gas to the oil in the crankcase, and, thus,
part of the losses added up by the increase in viscosity is
recovered.
[0052] FIG. 4 illustrates a fourth embodiment of the present
invention, where injecting nozzle 1 is positioned on the compressor
10 valve plate. This construction allows the oil to be atomized at
any moment in the compressor compression cycle, and not only during
one period of the compression cycle, as foreseen in the embodiments
of FIGS. 1 to 3. This embodiment is particularly convenient when
there is a low solubility of the cooling fluid in the lubricating
fluid, or when a highly efficient separator is used to separate the
lubricating fluid from the cooling fluid.
[0053] It will be appreciated that, while FIG. 4 illustrates an
embodiment where separator 5 and heat exchanger 6 are outside
housing 11, the arrangement of the injecting nozzle foreseen in
this embodiment could be used with these parts inside the
compressor, as in the embodiments illustrated in FIGS. 2 and 3.
[0054] FIG. 5 illustrates a fifth embodiment of the present
invention, where separator 5 and heat exchanger 6 comprise a single
component the function of which is both of a separator and a heat
exchanger.
[0055] Thus, as illustrated in this Figure, this single component
may comprise a heat separator with a heat dissipating element
(e.g., vanes), which removes from the oil the heat obtained in the
compression process. Naturally, other constructions may be equally
used, such as, for example, a coil-shaped heat exchanger arranged
around the separator.
[0056] In addition, while the single component is shown outside
compressor housing 11, such part could be housed inside housing 11,
as foreseen in the embodiments in FIGS. 3 and 4.
[0057] FIG. 6 illustrates still another embodiment of the present
invention, where heat exchanger 6 and separator 5 are positioned,
considering the circuit as formed, in an inverted manner to that
shown in the previous embodiment, this inverted arrangement
allowing the removal of heat before separation.
[0058] Naturally, the inverted arrangement shown in FIG. 6 may be
combined with the variations described in the previous embodiments,
regarding both the atomizing nozzle position and the possibility of
positioning the component parts inside housing 11.
[0059] By means of the described system, the present invention
allows for the achievement of improvements in the reliability and
performance of the compressor.
[0060] Regarding reliability, the lowering of the compressor
thermal profile caused by the atomization of the lubricating fluid
in the compression chamber avoids critical temperatures at points
in the compressor where the oil may undergo degradation and
irreversible changes in the thermo-physical properties. With the
compressor thermal profile lowered, it is also possible to
attenuate the severity of the product approval, wear and robustness
tests.
[0061] Regarding the performance, in its turn, the advantages
provided by the present invention are associated with the increase
in the volumetric efficiency and the energy efficiency of the
compressor.
[0062] With the compressor temperature levels lowered, the
overheating of the gas in the suction path decreases, resulting in
an increase in the coolant density at the start of the compression
process and, thus, in an increase in the amount of mass compressed
and pumped by the compressor. Thus, the compressor volumetric
efficiency increases, and, for the same pumping capacity, it may be
constructed in smaller dimensions.
[0063] In addition to the effects on the overheating along the
suction path, the oil atomized inside the compression chamber draws
heat from the cooling fluid during the compression process,
decreasing its temperature and specific volume. Thus, the
compression work decreases and the compressor efficiency
increases.
[0064] As a consequence, as a function of the increase in the
pumped mass and the decrease in the specific work, there is an
increase in the compressor energy efficiency, usually characterized
by the compressor Performance Coefficient (PCO).
[0065] Another benefit of the reduction of overheating during the
compression process is the decrease in the fluid flow rate in the
compressor valves, reducing the energy losses due to the viscous
friction and, thus, contributing to the increase in the PCO.
[0066] It should be pointed out that, in compressors with low
capacity for refrigeration applications, the presence of oil inside
the cylinder at the end of the compression process provides an
extra benefit since it reduces the amount of coolant in the dead
volume, increasing the volumetric efficiency.
[0067] Another complementary benefit lies in the better sealing of
the clearance between the piston and the cylinder by the oil, which
may favor the reduction of the losses inherent in the leak of gas
from within the compression chamber.
[0068] Eventually, it will be appreciated that description provided
based on the figures above relates only to embodiments possible for
the system of the present invention, the true scope of the object
of the invention being defined in the appended claims.
* * * * *