U.S. patent application number 10/094205 was filed with the patent office on 2003-09-11 for refrigeration system with liquid refrigerant injection to the condenser.
This patent application is currently assigned to VIA HOLDINGS, LLC. Invention is credited to Bai, Cheolho, Cho, Young I..
Application Number | 20030167792 10/094205 |
Document ID | / |
Family ID | 27788081 |
Filed Date | 2003-09-11 |
United States Patent
Application |
20030167792 |
Kind Code |
A1 |
Cho, Young I. ; et
al. |
September 11, 2003 |
Refrigeration system with liquid refrigerant injection to the
condenser
Abstract
A refrigeration system including a compressor, a condenser, an
expansion device and an evaporator connected in a closed circuit
through which a refrigerant is circulated. Liquid refrigerant is
injected between an outlet of the compressor and an inlet of the
condenser using a vacuum generator in which the vacuum is created
by the geometry of the device and the dynamic properties of fluid
flow therein, thereby allowing the refrigerant to be cooled at a
temperature close to its saturation temperature when it enters the
condenser without the need for a costly pump having moving parts.
The vacuum may be produced by vortex flow of the superheated vapor
output of the compressor, by flow of the superheated vapor through
the throat of a venturi device, or in any other comparable manner.
The refrigeration system may employ a single refrigerant or a
mixture of refrigerants such as R-134a, R-32 and R-125.
Inventors: |
Cho, Young I.; (Cherry Hill,
NJ) ; Bai, Cheolho; (Susung-ku, KR) |
Correspondence
Address: |
OSTROLENK FABER GERB & SOFFEN
1180 AVENUE OF THE AMERICAS
NEW YORK
NY
100368403
|
Assignee: |
VIA HOLDINGS, LLC
|
Family ID: |
27788081 |
Appl. No.: |
10/094205 |
Filed: |
March 6, 2002 |
Current U.S.
Class: |
62/500 ;
62/513 |
Current CPC
Class: |
F25B 2341/0014 20130101;
B60H 1/3204 20130101; F25B 6/04 20130101; B60H 1/3229 20130101;
F25B 41/00 20130101; F25B 9/006 20130101; F25B 9/04 20130101; B60H
2001/3295 20130101; F25B 2400/23 20130101 |
Class at
Publication: |
62/500 ;
62/513 |
International
Class: |
F25B 001/06; F25B
041/00 |
Claims
We claim:
1. A refrigeration system comprising: a compressor, a condenser
having an input and an output, an expansion device, and an
evaporator, connected together to form a closed loop system with a
refrigerant circulating therein; and a vacuum generating device
having no moving parts operative to inject a liquid portion of the
refrigerant exiting the condenser into the closed loop between an
outlet of the compressor and an inlet of the condenser.
2. A refrigeration system according to claim 1, further including a
valve that connects an inlet of the vacuum generating device to an
outlet of the condenser.
3. A refrigeration system according to claim 1, wherein the vacuum
generating device without moving parts which generates a pressure
differential as a result of fluid flow therethrough, and the
geometry thereof.
4. A refrigeration system according to claim 3, wherein the
pressure differential is generated by vortex flow of a pressurized
fluid.
5. A refrigeration system according to claim 3, wherein the
pressure differential is generated by flow of a pressurized fluid
through a passage of gradually decreasing size.
6. A refrigeration system according to claim 3, wherein the vacuum
generator is comprised of: a tubular body having an inlet end and
an axially opposite outlet end; a first inlet disposed axially at
the inlet end of the tubular body; a second inlet disposed
tangentially at the inlet end of the body, the second inlet and the
geometry of the inlet end of the body being operative to cause
helical flow of fluid entering the second inlet toward the outlet
end of the tubular body; and an axially disposed outlet at the
outlet end of the tubular body, the helical flow path producing a
lower pressure along the axis of the tubular member compared to
that at the radially outer end thereof.
7. A refrigeration system according to claim 6, wherein: the first
inlet of the vacuum generator is connected to an outlet of the
condenser; the second inlet of the vacuum generator is connected to
the outlet of the compressor; and the outlet of the vacuum
generator is connected to the inlet of the condenser.
8. A refrigeration system according to claim 7, wherein the first
inlet of the vacuum generator is connected to the outlet of the
condenser through a valve.
9. A refrigeration system according to claim 3, wherein the vacuum
generator is comprised of: a tubular body having first and second
opposite ends; a first fluid inlet disposed axially at the first
end of the tubular body; a fluid outlet axially disposed outlet at
the second end of the tubular body, the passage between the first
inlet and the outlet having a cross-sectional area which decreases
to a throat of minimum cross-section; and a second fluid inlet
disposed radially at the throat inlet end of the body, the flow of
fluid from the first inlet through the throat being operative to
produce a lower pressure at the throat and the second inlet
compared to that at the first inlet.
10. A refrigeration system according to claim 9, wherein: the first
inlet of the vacuum generator is connected to an outlet of the
compressor; the second inlet of the vacuum generator is connected
to the outlet of the condenser; and the outlet of the vacuum
generator is connected to the inlet of the condenser.
11. A refrigeration system according to claim 10, wherein the
second inlet of the vacuum generator is connected to the outlet of
the condenser through a valve.
12. A refrigeration system comprising: a compressor, a condenser
having an input and an output, an expansion device, and an
evaporator, connected together to form a closed loop system with a
refrigerant circulating therein, the refrigerant including a
plurality of components having differing thermal characteristics; a
liquid-vapor separator connected to an outlet of the condenser, and
a operative to extract a liquid component from the refrigerant
exiting from the condenser, to provide the liquid component at a
first outlet thereof, and to provide the residual vapor component
at a second outlet thereof; and a vacuum generating device having
no moving parts operative to inject the liquid component of the
refrigerant extracted by the liquid-vapor separator into the closed
loop between an outlet of the compressor and an inlet of the
condenser.
13. A refrigeration system according to claim 12, further including
a valve that connects an inlet of the vacuum generating device to
an outlet of the liquid-vapor separator.
14. A refrigeration system according to claim 12, wherein the
vacuum generator generates a pressure differential as a result of
fluid flow therethrough, and the geometry thereof.
15. A refrigeration system according to claim 14, wherein the
pressure differential is generated by vortex flow of a pressurized
fluid.
16. A refrigeration system according to claim 14, wherein the
pressure differential is generated by flow of a pressurized fluid
through a passage of gradually decreasing size.
17. A refrigeration system according to claim 14, wherein the
vacuum generator is comprised of: a tubular body having an inlet
end and an axially opposite outlet end; a first inlet disposed
axially at the inlet end of the tubular body; a second inlet
disposed tangentially at the inlet end of the body, the second
inlet and the inlet end of the body being operative to cause
helical flow of fluid entering the second inlet toward the outlet
end of the tubular body; and an axially disposed outlet at the
outlet end of the tubular body, the helical flow path producing a
lower pressure along the axis of the tubular member compared to
that at the radially outer end thereof.
18. A refrigeration system according to claim 17, wherein: the
first inlet of the vacuum generator is connected to an outlet of
the condenser; the second inlet of the vacuum generator is
connected to the outlet of the compressor; and the outlet of the
vacuum generator is connected to the inlet of the condenser.
19. A refrigeration system according to claim 18, wherein the first
inlet of the vacuum generator is connected to the outlet of the
condenser through a valve.
20. A refrigeration system according to claim 14, wherein the
vacuum generator is comprised of: a tubular body having first and
second opposite ends; a first fluid inlet disposed axially at the
first end of the tubular body; a fluid outlet axially disposed
outlet at the second end of the tubular body, the passage between
the first inlet and the outlet having a cross-sectional area which
decreases to a throat of minimum cross-section; and a second fluid
inlet disposed radially at the throat inlet end of the body, the
flow of fluid from the first inlet through the throat being
operative to produce a lower pressure at the throat and the second
inlet compared to that at the first inlet.
21. A refrigeration system according to claim 20, wherein: the
first inlet of the vacuum generator is connected to an outlet of
the compressor; the second inlet of the vacuum generator is
connected to the outlet of the condenser; and the outlet of the
vacuum generator is connected to the inlet of the condenser.
22. A refrigeration system according to claim 21, wherein the
second inlet of the vacuum generator is connected to the outlet of
the condenser through a valve.
23. A refrigeration system according to claim 12, wherein: the
condenser is comprised of first and second condenser stages; the
inlet of the liquid-vapor separator is connected to an outlet of
the first condenser stage; the first outlet of the liquid-vapor
separator is connected to an inlet of the vacuum generating device;
the second outlet of the liquid-vapor separator is connected to an
inlet of the second condenser stage; and an outlet of the second
condenser stage is connected to an inlet of the expansion
device.
24. A refrigeration system according to claim 12, wherein the
refrigerant is a mixture of R-32, R-125 and R-134a, and the liquid
provided at the output of the LV separator is rich in R-134a.
Description
FIELD OF THE INVENTION
[0001] The present invention relates generally to a high efficiency
refrigeration system and, more specifically, to a refrigeration
system utilizing one or more vortex tubes for increasing the
overall efficiency of a refrigeration system.
BACKGROUND OF THE INVENTION
[0002] FIG. 1 is a block diagram of a conventional refrigeration
system, generally denoted at 10. The system includes a compressor
12, a condenser 14, an expansion device 16 and an evaporator 18.
The various components are connected together via copper tubing
such as indicated at 20 to form a closed loop system through which
a refrigerant such as R-12, R-22, R-134a, R-407c, R-410a, ammonia,
carbon dioxide or natural gas is cycled.
[0003] The main steps in the refrigeration cycle are compression of
the refrigerant by compressor 12, heat extraction from the
refrigerant to the environment by condenser 14, throttling of the
refrigerant in the expansion device 16, and heat absorption by the
refrigerant from the space being cooled in evaporator 18. This
process, sometimes referred to as a vapor-compression refrigeration
cycle, is used in air conditioning systems, which cool and
dehumidify air in a living space, in a moving vehicle (e.g.,
automobile, airplane, train, etc.), refrigerators and heat
pumps.
[0004] FIG. 2 shows the temperature-entropy curve for the vapor
compression refrigeration cycle illustrated in FIG. 1. The
refrigerant exits evaporator 18 as a saturated vapor (Point 1), and
is compressed by compressor 12 to a very high pressure. The
temperature of the refrigerant also increases during compression,
and it leaves the compressor as superheated vapor (Point 2).
[0005] A typical condenser comprises a single conduit formed into a
serpentine-like shape with a plurality of rows of conduit lying in
a spaced parallel relationship. Metal fins or other structures
which provide high heat conductivity are usually attached to the
serpentine conduit to maximize the transfer of heat between the
refrigerant passing through the condenser and the ambient air. As
the superheated refrigerant gives up heat in the upstream portion
of the condenser, the superheated vapor becomes a saturated vapor
(Point 2a), and after losing further heat as it travels through the
remainder of condenser 14, the refrigerant exits as saturated
liquid (Point 3).
[0006] As the saturated liquid refrigerant passes through expansion
device 16, its pressure is reduced, and it becomes a liquid-vapor
mixture comprised of approximately 20% vapor and 80% liquid. Also,
its temperature drops below the temperature of the ambient air as
it goes through the expansion device (Point 4 in FIG. 2).
[0007] Evaporator 18 physically resembles the serpentine-shaped
conduit of the condenser. Air to be cooled is exposed to the
surface of the evaporator where heat is transferred to the
refrigerant. As the refrigerant absorbs heat in evaporator 18, it
becomes a saturated or slightly superheated vapor at the suction
pressure of the compressor and reenters the compressor thereby
completing the cycle (Point 1 in FIG. 2).
[0008] The injection of liquid refrigerant to the discharge line of
the compressor or the inlet of the condenser in a conventional
refrigeration system such as illustrated in FIG. 1 has been used to
make the condenser more efficient. Referring to FIG. 3 (in which
parts corresponding to those of FIG. 1 are given the same reference
numerals), to provide liquid injection according to known practice,
in addition to the above-described components, a bypass circuit 22
is coupled across condenser 14. This includes a pump 24, the inlet
of which is coupled by a tube 26 to the outlet of condenser 14
through a suitable diverter valve (not shown). The outlet of pump
24 is coupled by a tube 28 and a suitable check valve (also not
shown) to a further tube 30 which connects the outlet of compressor
12 and the inlet of condenser 14.
[0009] Liquid refrigerant is injected into tube 30 to cool the
superheated vapor exiting compressor 12 before it reaches the
condenser. As the liquid refrigerant and the superheated vapor mix,
the liquid flashes to a superheated vapor, and its temperature
drops substantially. As a result, the superheated vapor can enter
the condenser at a temperature close to its saturation temperature.
This is illustrated in the modified temperature-entropy curve of
FIG. 4 between Points 2 and 2a.
[0010] As will be understood, the liquid pressure at the condenser
exit is slightly lower than the vapor pressure at the condenser
inlet. Accordingly pump 24 must be used to pressurize the
liquid.
[0011] Generally, however, the cost of the pump does not justify
the benefit gained by the liquid injection, so the concept of
liquid injection has not been widely utilized in the
air-conditioning and refrigeration industry.
[0012] Nevertheless, FIG. 4 demonstrates that with liquid
injection, the portion of condenser 14 in which the superheated
vapor is converted from superheated vapor to (lower temperature)
saturated vapor (between Points 2 and 2a in FIG. 2) may be
eliminated, thus reducing the manufacturing cost. Alternatively,
for a condenser of a particular size, greater supercooling can be
achieved (as indicated at Point 3 in FIG. 4). This results in
increased cooling capacity.
[0013] An additional benefit which can be achieved by use of liquid
injection, assuming that the negative effect on cost resulting from
the need for pump 24 can be overcome, is an improved
energy-efficiency ratio (EER). This is defined as Qv/Wc, where Qv
is the heat absorption by the evaporator of the system and Wc is
the work done by the compressor. As liquid injection increases
supercooling, it also results in a greater quantity of liquid in
the refrigerant entering the evaporator. This increases the cooling
capacity Qv, thus the EER also increases.
[0014] Therefore a need exists for a cost-effective way to provide
injection of liquid refrigerant at the inlet side of the
condenser.
SUMMARY OF THE INVENTION
[0015] According to the present invention, it has been found that a
vacuum generating device with no moving parts can be used instead
of a pump for the liquid injection. Such devices rely on geometry
and fluid dynamics to create pressure differentials. Known devices
of this type include venturi tubes and ejectors or syphons. Also,
it has been found that the so-called "vortex tube" which is
conventionally used to create two fluid steams of differing
temperature from a single high pressure input stream can be adapted
to function as a vacuum generating device, and may be used for that
purpose according to the present invention. Such a vortex generator
is the subject of a copending U.S. provisional patent application
entitled USE OF A VORTEX GENERATOR TO GENERATE VACUUM, filed in the
names of Young Cho, Cheolho Bai, and Joong-Hyoung Lee on Feb. 11,
2002, the contents of which are hereby incorporated by
reference.
[0016] The concepts of this invention are applicable to
conventional single-refrigerant systems, and also to
mixed-refrigerant systems using a combination of refrigerants
selected to provide the desired combination of thermal and
flammability characteristics. Such mixed-refrigerant systems may
also include regenerative features which provide higher evaporator
efficiency by increasing the percentage of liquid in the
refrigerant as it enters the evaporator. Regenerative mixed
refrigerant systems are disclosed, for example, in our U.S. Pat.
Nos. 6,250,086 and 6,293,108, the contents of which are hereby
incorporated by reference.
[0017] According to a first feature of the invention, there is
provided a refrigeration system including refrigerant compressing
means, refrigerant condensing means, expansion means and
evaporation means connected together to form a closed loop system
with a refrigerant circulating therein, and vacuum generating means
for receiving liquid refrigerant from an outlet of the condensing
means and for injecting the liquid refrigerant into the closed loop
between the outlet of the compressing means and an inlet of the
condensing means.
[0018] According to a second feature of the invention, there is
provided a refrigeration system including refrigerant compressing
means, refrigerant condensing means, expansion means and
evaporation means connected together to form a closed loop system,
vacuum generating means, means for coupling an outlet of the
condensing means to an inlet of the vacuum generating means, and
means for coupling an outlet of the vacuum generating means to an
inlet of the condensing means.
[0019] According to a third feature of the invention, there is
provided a refrigeration system including a compressor, a
condenser, an expansion device and an evaporator connected together
to form a closed loop system with a refrigerant circulating
therein, and a vacuum generating device operative to inject a
liquid portion of the refrigerant exiting the condenser into the
closed loop between an outlet of the compressor and an inlet of the
condenser.
[0020] According to a fourth feature of the invention, there is
provided a refrigeration system including a compressor, a
condenser, an expansion device and an evaporator connected together
to form a closed loop system with a refrigerant circulating
therein, a vacuum generating device coupled to an outlet of the
condenser and operative to inject a liquid portion of the
refrigerant exiting the condenser into the closed loop between an
outlet of the compressor and an inlet of the condenser.
[0021] According to a fifth feature of the invention, a vacuum
generating device injects liquified refrigerant into the inlet of
the condenser of a refrigeration system employing a
vapor-compression refrigeration cycle.
[0022] According to a sixth feature of the invention, and with
respect to each of the above-described other features, the vacuum
generator is a device without moving parts which generates a
pressure differential as a result of the geometry of the device and
the fluid flow therethrough. Such devices include a modified vortex
tube, venturis, ejectors or siphons, etc.
[0023] Also with respect to each of the above-described features of
the invention, the refrigeration system may employ a single
refrigerant, or a mixture of refrigerants selected to provide the
desired combination of thermal and flammability characteristics and
may include regenerative features which provide higher evaporator
efficiency by increasing the percentage of liquid in the
refrigerant as it enters the evaporator.
[0024] According to a seventh feature of the invention, there is
provided a novel vortex generator which functions as a vacuum
generating device without moving parts.
[0025] It is therefore an object of the invention to increase the
efficiency of known refrigeration systems by providing a
cost-effective way of injecting liquid refrigerant into the inlet
of the condenser.
[0026] It is another object of the invention to increase the
cooling capacity and EER of known refrigeration systems by
providing a cost-effective way of injecting liquid refrigerant into
the inlet of the condenser.
[0027] A related object of the invention to allow use of smaller
condensers in known refrigeration systems by providing a
cost-effective way of injecting liquid refrigerant into the inlet
of the condenser.
[0028] An additional object of the invention is to provide improved
liquid refrigerant injection apparatus which may be used in
single-refrigerant systems and also in mixed-refrigerant systems,
with and without regenerative features.
[0029] A further object of the invention is to provide an improved
refrigeration system including a device for injecting liquid
refrigerant into the inlet of the condenser without the need for a
costly pump.
[0030] A related object of the invention is to provide an improved
refrigeration system in which the device for injecting liquid
refrigerant into the inlet of the condenser is a vacuum generating
device having no moving parts.
[0031] An additional related object of the invention is to provide
an improved refrigeration system in which the device for injecting
liquid refrigerant is a vacuum generating device which creates a
pressure differential due to vortex flow, and which requires no
moving parts.
BRIEF DESCRIPTION OF THE DRAWINGS
[0032] FIG. 1 shows a block diagram of a conventional refrigeration
system.
[0033] FIG. 2 shows a temperature-entropy curve for the
conventional refrigeration system of FIG. 1.
[0034] FIG. 3 shows a block diagram of a conventional refrigeration
system in which liquid refrigerant is injected into the condenser
inlet using a pump.
[0035] FIG. 4 shows a temperature-entropy curve for the
refrigeration system of FIG. 3.
[0036] FIG. 5 shows a block diagram of an embodiment of the present
invention in which a vortex generator is used to inject liquid
refrigerant into the condenser inlet.
[0037] FIGS. 6A and 6B illustrate the construction of a vortex
generator according to the invention.
[0038] FIG. 7 illustrates the construction of a venturi which may
be used instead of the vortex generator shown in FIGS. 6A and
6B.
[0039] FIG. 8 shows a block diagram of a second embodiment in which
the present invention applied to a mixed-refrigerant system.
[0040] Throughout the drawings, like parts are given the same
reference numerals.
DETAILED DESCRIPTION
[0041] FIG. 5 illustrates in block diagram form, a first embodiment
of the invention in which a vortex generator is used instead of a
pump. The system of FIG. 5, generally denoted at 40, is similar to
that of FIG. 3, except that in bypass circuit 42 coupled across
condenser 14, pump 24 is replaced by a vortex generator (VG) 44,
described in more detail below. A valve 46 is coupled by a tube 48
to the outlet of condenser 14, and by a second tube 50 to a first
inlet 54 of VG 44. A second inlet 52 of VG 44 is coupled to the
outlet of compressor 12 by a tube 56. The outlet 58 of VG 44 is
coupled by tube 30 to the inlet of condenser 14.
[0042] The construction of VG 44 is shown schematically in FIGS. 6A
and 6B. The design of VG 44 is derived from the so-called vortex
tube, a known device which converts an incoming flow of compressed
gas into two outlet streams--one stream hotter than and the other
stream colder than the temperature of the gas supplied to the
vortex tube. A vortex tube does not contain any moving parts. The
conventional version of a vortex tube, e.g., used for fluid
separation in refrigeration systems, is illustrated in our U.S.
Pat. No. 6,250,086, which is hereby incorporated herein by
reference.
[0043] As illustrated in FIGS. 6A and 6B, a vortex generator
according to this invention is comprised of a tubular body 60, with
an axial inlet 52 and a tangential inlet 54 at an inlet end 62, and
an outlet 58 at an opposite outlet end 64. The interior
construction of tube 60 at the inlet end is such that a high
pressure gas stream entering tangential inlet 54 travels along a
helical path toward the outlet 58. This produces a strong vortex
flow in tube 60, and a radial pressure differential due to the
centrifugal force created by the vortex flow forces the vapor
radially outward and produces high pressure at the periphery and
low pressure at the axis. The low pressure allows fluid drawn in
through axial inlet 52 to mix with the high pressure helical stream
and to exit with it through outlet 58.
[0044] Further information concerning VG 44 may be found in the
Cho, Bai, Lee Application mentioned above.
[0045] In the system illustrated in FIG. 5, the high pressure
tangential flow is provided through tube 56 from compressor 12, and
the incoming stream at axial inlet 52 is provided from the outlet
of condenser 14 through valve 46 and tubes 48 and 50. Using a
vacuum generating device based on the vortex tube makes it possible
to provide injection of liquid refrigerant between the outlet of
the compressor 12 and the inlet of condenser 14 without the need
for a costly pump having moving parts.
[0046] Other devices which rely on geometry and fluid dynamics may
also be used to generate a vacuum which permits liquid refrigerant
injection without use of a mechanical pump. For example, a device
operating on the principle of a venturi tube may also be used. In
such a device, as illustrated in FIG. 7, a high pressure fluid
stream (here, the superheated vapor output of compressor 12),
enters axially into an elongated tube 70 having an interior
diameter 72 which decreases gradually to a point of minimum
diameter 74 and thereafter increases gradually toward an outlet end
76. As the cross-sectional area decreases, the vapor stream is
accelerated. According to Bemoulli's principle, the pressure
decreases, and reaches a minimum at the so-called "throat
corresponding to the point of minimum diameter 74 where a vacuum is
created.
[0047] A radial inlet 78 is provided at the low-pressure point.
This is connected by tubes 48 and 50, and valve 46 to the outlet of
condenser 14 (see FIG. 5), thereby permitting mixture of the liquid
refrigerant with the axial stream of superheated vapor from
compressor 12.
[0048] Yet another possible device for creating a vacuum without
reliance on a pump is the so-called ejector, sometimes also called
a syphon or eductor.
[0049] In the constructions described above, it has been assumed
that a single refrigerant circulates through the system. Liquid
injection can also be used in conjunction with mixed refrigerants
in regenerative systems to achieve highly beneficial results.
[0050] FIG. 8 illustrates use of liquid injection in a simple
mixed-refrigerant system, employing, for example, a mixture of
refrigerants R-32, R-125, and R-134a. This is a commonly used
beneficial combination as the R-32 component is flammable, but
possesses excellent thermal characteristics, while the R-125 and
R-134a components exhibit less desirable thermal characteristics
than R-32 but are non-flammable. In the interest of simplicity,
various possible regenerative paths as illustrated in our
above-identified U.S. patents have been omitted from the
illustrative system of FIG. 8.
[0051] The system, generally denoted at 86, comprises a compressor
12, an expansion device 16, and an evaporator 18. The condenser,
however, is split into two stages designated 14a and 14b, and a
liquid-vapor (LV) separator 88 of any suitable or desired type is
provided between the two condenser stages.
[0052] LV separator 88 functions to separate the incoming vapor
stream exiting from condenser stage 14a into a vapor component
which passes through tube 90 to the inlet of condenser stage 14b,
and a lower temperature liquid component which passes through a
tube 92, a valve 46, and a second tube 50 to the axial inlet 52 of
VG 44 (see FIGS. 6A and 6B). The tangential inlet 54 of VG 44 is
coupled to the outlet of compressor 12 by a tube 56, and the outlet
58 of VG 44 is coupled to the inlet of the first condenser stage
14a by a tube 30. In connection with the above description it
should be understood that instead of VG 44, the venturi device 70
illustrated in FIG. 7, or other comparable device, may be used.
[0053] The liquid exiting from LV separator 88 is rich in the
R-134a refrigerant component due to its high boiling point relative
to the other refrigerant components. Aside from the advantages of
liquid injection as described above, returning part of the R-134a
to the condenser in liquid form has the added benefit of lowering
the condenser pressure, thus further reducing the compressor
work.
[0054] In summary, use of liquid injection in mixed refrigerant
systems allows the refrigerant to enter the condenser as an almost
saturated vapor which eliminates the need for a desuperheating
section in the condenser and increases the supercooling of the
refrigerant exiting the condenser. It also reduces the condenser
pressure, and thus reduces the compressor work.
[0055] As indicated above, the system illustrated in FIG. 8 is
representative of the application of the principles of this
invention to mixed-refrigerant regenerative systems. It should
therefore be understood, that liquid refrigerant injection to the
condenser is applicable to other mixed-refrigerant regenerative
system configurations as well.
[0056] In describing the invention, specific terminology has been
employed for the sake of clarity. However, the invention is not
intended to be limited to the specific descriptive terms, and it is
to be understood that each specific term includes all technical
equivalents that operate in a similar manner to accomplish a
similar purpose.
[0057] Similarly, the embodiments described and illustrated are
also intended to be exemplary, and various changes and
modifications, and other embodiments within the scope of the
invention will be apparent to those skilled in the art in light of
the disclosure. The scope of the invention is therefore intended to
be defined and limited only by the appended claims, and not by the
description herein.
* * * * *