U.S. patent application number 09/760232 was filed with the patent office on 2001-09-13 for method and apparatus for increasing the efficiency of a refrigeration system.
Invention is credited to Bai, Cheolho, Cho, Young I..
Application Number | 20010020366 09/760232 |
Document ID | / |
Family ID | 27414679 |
Filed Date | 2001-09-13 |
United States Patent
Application |
20010020366 |
Kind Code |
A1 |
Cho, Young I. ; et
al. |
September 13, 2001 |
Method and apparatus for increasing the efficiency of a
refrigeration system
Abstract
A refrigeration system utilizing a vortex generator and a
diffuser to reduce the pressure differential between the head
pressure and suction pressure across a compressor.
Inventors: |
Cho, Young I.; (Cherry Hill,
NJ) ; Bai, Cheolho; (Taegu, KR) |
Correspondence
Address: |
Mark A. Garzia, Esquire
P.O. Box 288
Media
PA
19063-0288
US
|
Family ID: |
27414679 |
Appl. No.: |
09/760232 |
Filed: |
January 12, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09760232 |
Jan 12, 2001 |
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09517922 |
Mar 3, 2000 |
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6250086 |
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09760232 |
Jan 12, 2001 |
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09535126 |
Mar 24, 2000 |
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09760232 |
Jan 12, 2001 |
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09737016 |
Dec 14, 2000 |
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Current U.S.
Class: |
62/5 ;
62/498 |
Current CPC
Class: |
F25B 41/00 20130101;
F25B 2341/0015 20130101; F25B 9/008 20130101; F25B 2341/0012
20130101; F25B 43/00 20130101; F25B 2309/06 20130101; F25B 2400/23
20130101; F25B 2341/0011 20130101; F25B 2341/0014 20130101; F25B
9/04 20130101; B01D 45/16 20130101; B60H 2001/3298 20130101 |
Class at
Publication: |
62/5 ;
62/498 |
International
Class: |
F25B 009/02; F25B
001/00 |
Claims
We claim:
1. A refrigeration system having a compressor, a condenser, an
expansion device and an evaporator arranged in succession and
connected via conduit in a closed loop in order to circulate
refrigerant through the closed loop, the refrigeration system
comprising means for decreasing pressure differential across the
compressor, thus decreasing compression ratio in the
compressor.
2. The refrigeration system of claim 1 wherein said means for
decreasing comprises a vortex generator and a means for slowing
refrigerant flow, in combination, that communicate with the
expansion device, the evaporator and the compressor for increasing
the inlet pressure of the compressor.
3. The refrigeration system of claim 2 wherein said means for
slowing refrigerant flow is a diffuser.
4. The refrigeration system of claim 2 wherein said means for
slowing refrigerant flow is a sudden expansion of the conduit.
5. The refrigeration system of claim 2 wherein said vortex
generator utilizes a center delivery for introducing recirculated
refrigerant from the evaporator directly into the vortex flow.
6. A refrigeration system comprising: a compressor; a condenser; an
expansion device; and an evaporator, all arranged in succession and
communicating via conduit in a closed loop in order to circulate
refrigerant through the closed loop; a vortex generator for
separating a stream of refrigerant under relatively high pressure
into a vapor component and a liquid component, said vortex
generator placed in the closed loop between the expansion device
and the evaporator for accelerating the refrigerant vapor to a very
high velocity at the exit of said vortex generator; and a diffuser
placed between the vortex generator and the compressor for
increasing the pressure of the refrigerant before the refrigerant
enters the compressor thereby reducing the pressure differential
across the compressor and the compression ratio in the
compressor.
7. The refrigeration system of claim 6 wherein said vortex
generator has a primary input, a secondary input, a vapor output
and a liquid output, such that the output of the expansion device
is connected to the primary input of the vortex generator, the
vapor output of the vortex generator is connected to the input of
the diffuser, the liquid output of the vortex generator is
connected to the evaporator and the output of the evaporator is
connected to the secondary input of the vortex generator.
8. The refrigeration system of claim 6 further comprises a second
vortex generator having an inlet and an outlet placed about
one-fourth of the way in to the condenser.
9. The refrigeration system of claim 8 wherein said expansion
device is a third vortex generator having an inlet and an
outlet.
10. The refrigeration system of claim 6 wherein said expansion
device is a first vortex generator having an inlet and an
outlet.
11. The refrigeration system of claim 6, wherein said expansion
device is a capillary tube for adjusting the pressure of the
refrigerant that passes therethrough.
12. The refrigeration system of claim 6 wherein said vortex
generator has a center delivery for introducing recirculated
refrigerant directly into the vortex flow.
13. A refrigeration system comprising: a compressor having an inlet
and an outlet; a condenser having an inlet and an outlet, said
condenser connected to the compressor via a first tube; an
expansion device having an inlet and an outlet, the inlet of the
expansion device connected to the outlet of the condenser via a
second tube; a vortex generator for separating a stream of
refrigerant into a vapor component and a liquid, said vortex
generator having a primary input, a secondary input, a vapor output
and a liquid output, such that the outlet of the expansion device
is connected to the primary input of the vortex generator via a
third tube; an evaporator having an inlet and an outlet, the liquid
outlet of the vortex generator being connected to the inlet of the
evaporator via a fourth tube, and the outlet of the evaporator
connected to the secondary input of the vortex generator via a
fifth tube; a diffuser having an inlet and an outlet, the vapor
outlet of the vortex generator connected to the inlet of the
diffuser via sixth tube, and the outlet of the diffuser connected
to the inlet of the compressor via a seventh tube, the vortex
generator and the diffuser increasing the pressure of the
refrigerant entering the compressor thereby reducing the pressure
differential across the compressor and the compression ratio in
compressor.
14. The refrigeration system of claim 13, further comprising a
bypass tube connecting the outlet of the evaporator to the inlet of
the diffuser (i.e., connecting the fifth tube to the sixth
tube).
15. The refrigeration system of claim 14, further comprising a
valve in the bypass tube for regulating the amount of refrigerant
that passes through the bypass tube.
16. The refrigeration system of claim 14, further comprising a
second vortex generator having an inlet and an outlet placed about
one-fourth of the way in to the condenser.
17. The refrigeration system of claim 14, wherein said expansion
device is a third vortex generator having an inlet and an
outlet.
18. The refrigeration system of claim 13, wherein said expansion
device is a vortex generator having an inlet and an outlet.
19. The refrigeration system of claim 13, wherein said expansion
device is a capillary tube for adjusting the pressure of the
refrigerant that passes therethrough.
20. A method of improving the efficiency of a refrigeration system,
the refrigeration system having a compressor, a condenser, an
expansion device, and,-an evaporator, and a diffuser arranged in
succession and connected via conduit in a closed loop in order to
circulate refrigerant through the closed loop, the method
comprising the steps of. a) separating a stream of refrigerant
exiting the expansion device using vortex generator into a vapor
component and a liquid component; b) directing the liquid component
to the evaporator; c) directing the high velocity vapor component
exiting from vortex generator to a means for slowing the velocity
of refrigerant flow and for increasing the pressure on the
refrigerant before the refrigerant enters the compressor, thereby
decreasing the pressure differential across the compressor and the
compression ratio in compressor.
21. The method of claim 20 wherein said means for slowing
refrigerant flow comprises the step of directing the refrigerant
into a diffuser.
22. The method of claim 20 wherein said means for slowing
refrigerant flow is a sudden expansion of the conduit.
23. The method of claims 20 further comprising the step of
directing a portion of the recirculated refrigerant from the
evaportor through a central delivery of the vortex generator
directly into the vortex flow.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. application Ser.
No. 09/517,922 filed Mar. 3, 2000, entitled HIGH-EFFICIENCY
REFRIGERATION SYSTEM; U.S. application Ser. No. 09/535,126 filed
Mar. 24, 2000, entitled HIGH-EFFICIENCY REFRIGERATION SYSTEM; and
U.S. application Ser. No. 09/737,016 filed on Dec. 14, 2000,
entitled VORTEX GENERATOR, in the names of Young I. Cho and Cheolho
Bai.
FIELD OF THE INVENTION
[0002] The present invention relates generally to a high efficiency
refrigeration system and, more specifically, to a refrigeration
system utilizing one or more vortex generators and a diffuser to
increase the overall efficiency of a refrigeration system.
BACKGROUND OF THE INVENTION
[0003] A refrigeration system typically consists of four major
components connected together via a conduit (preferably copper
tubing) to form a closed loop system. Referring to FIG. 1, a
conventional refrigeration system 500 is illustrated. The four
major components are a compressor 52, a condenser 54, an expansion
device 56 and an evaporator 58. A refrigerant circulates through
the four components via the conduit 59 and will have its pressure
either increased or decreased, and its temperature either increased
or decreased by the four components.
[0004] The refrigerant is continuously cycled through the
refrigeration system. The main steps in the refrigeration cycle are
compression of the refrigerant by the compressor 52, heat rejection
of the refrigerant in the condenser 54, throttling of the
refrigerant in the expansion device 56, and heat absorption of the
refrigerant in the evaporator 58. This process is sometimes
referred to as a vapor-compression refrigeration cycle. The
compressor 52 includes a motor (usually an electric motor) and
provides the energy to keep the refrigerant moving within the
conduits and through the major components.
[0005] The vapor-compression refrigeration cycle is the principle
upon which conventional air conditioning systems, heat pumps, and
refrigeration systems are able to cool and dehumidify air in a
defined volume (e.g., a living space, a vehicle, a freezer, etc.)
The vapor-compression cycle is made possible because the
refrigerant is a condensible gas and exhibits specific properties
when it is placed under varying pressures and temperatures.
[0006] During the refrigeration cycle, the refrigerant enters the
compressor as saturated vapor and is compressed to a very high
pressure. The temperature of the refrigerant increases during the
compression step. The refrigerant leaves the compressor as
superheated vapor and enters the condenser.
[0007] A typical condenser comprises a single conduit formed into a
serpentine-like shape so that a plurality of rows of conduit are
formed parallel to each other. Metal fins or other aids are usually
attached to the outer surface of the serpentine conduit in order to
increase the transfer of heat between the superheated refrigerant
vapor passing through the condenser and the ambient air. Heat is
rejected from the superheated vapor as it passes through the
condenser and the refrigerant exits the condenser as a saturated or
subcooled liquid.
[0008] The expansion device reduces the pressure of the liquid
refrigerant thereby turning it into a saturated liquid-vapor
mixture, which is throttled to the evaporator. In order to reduce
manufacturing costs, the expansion device is typically a capillary
tube in small air conditioning systems. The temperature of the
refrigerant drops below the temperature of the ambient air as it
passes through the expansion device. The refrigerant enters the
evaporator as a low quality saturated mixture comprised of
approximately 20% vapor and 80% liquid. ("Quality" is defined as
the mass fraction of vapor in the liquid-vapor mixture.)
[0009] The evaporator physically resembles the serpentine-shaped
conduit of the condenser. Ideally, the refrigerant completely
evaporates by absorbing heat from the defined volume to be cooled
(e.g., the interior of a refrigerator) and leaves the evaporator as
saturated vapor at the suction pressure of the compressor and
reenters the compressor thereby completing the cycle.
[0010] The efficiency of a refrigeration cycle is traditionally
described by an energy-efficiency ratio (EER). It is defined as the
ratio of the heat absorption from an evaporator to the work done by
a compressor. 1 EER = Heat absorption from evaporator Work done by
compressor
[0011] In a typical air conditioning system, the refrigeration
cycle has an EER of approximately 3.0 (kw/kw). As can be seen from
the EER equation, the efficiency of the refrigeration system
increases by decreasing the work performed by the compressor.
[0012] Vortex tubes are well known. Typical vortex tubes are
designed to operate with non-condensible gas such as air. A typical
vortex tube turns compressed air into two air streams, one of
relatively hot air and the other of relatively cold air. A common
application for prior vortex tubes is in air supply lines and other
applications which utilize gas under a high pressure.
[0013] A vortex tube does not have any moving parts. A vortex tube
operates by imparting a rotational vortex motion to an incoming
compressed air stream; this is done by directing compressed air
into an elongated channel in a tangential direction.
SUMMARY OF THE INVENTION
[0014] The present invention increases the efficiency of a
refrigeration, air conditioning or heat pump system by increasing
the efficiency of the refrigeration cycle. The increase in the
efficiency is achieved by utilizing a diffuser that communicates
with a compressor to reduce the pressure differential across the
compressor and a vortex generator to assist in the conversion of
the refrigerant from vapor to liquid at specific points in the
refrigeration cycle.
[0015] A vortex generator is designed to work specifically with
condensible vapors such as refrigerants. In one embodiment, a
vortex generator is placed between the expansion device and the
evaporator in order to increase the percentage of refrigerant
entering the evaporator as a liquid, and a diffuser is placed
between the vortex generator and the compressor in order to
increase the pressure of vapor refrigerant before the vapor enters
the compressor, which will reduce the pressure differential across
the compressor. As a result, the compression ratio at the
compressor decreases, and the work required by the compressor is
reduced, thus increasing the efficiency (EER) of the refrigeration
cycle.
[0016] Since the heat absorption from the evaporator occurs through
the evaporation of the liquid refrigerant, an increase in the
percentage of the liquid refrigerant entering the evaporator
increases the efficiency (EER) of the refrigeration cycle and
reduces the size of the evaporator for the same BTU output (i.e.,
cooling capacity) refrigeration system.
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] The accompanying drawings, which are incorporated in and
form a part of the specification, illustrate the embodiments of the
present invention and, together with the description, serve to
explain the principles of the invention.
[0018] In the drawings:
[0019] FIG. 1 is a block diagram of a conventional refrigeration
system;
[0020] FIG. 2 is a block diagram of a refrigeration system
utilizing a vortex generator and a diffuser in accordance with the
present invention;
[0021] FIG. 3A is a side cross-sectional view of a single-inlet,
single-outlet vortex generator utilizing a tangential feed in the
nozzle;
[0022] FIG. 3B is a top cross-sectional view of the vortex
generator shown in FIG. 3A;
[0023] FIGS. 4A and 4B are diagrammatic representations
illustrating the principle of phase-changing of the vapor inside
the vortex generator of the present invention;
[0024] FIG. 5 is a representation of the cascade effect produced
inside of a vortex generator in accordance with the present
invention;
[0025] FIG. 6A is a more detailed view of the single-inlet, single
outlet vortex generator illustrated in FIG. 3A;
[0026] FIGS. 6B is a side view, and
[0027] FIG. 6C is an end view, of a nozzle used in the vortex
generator of FIG. 6A;
[0028] FIG. 7 is a cross-sectional side view of another embodiment
of a vortex generator in accordance with the present invention
using two inlets and two outlets;
[0029] FIG. 8 is a block diagram of another embodiment of a
refrigeration system in accordance with the present invention
utilizing a vortex generator, a diffuser and a branch connection
proximate the evaporator;
[0030] FIG. 9 is a block diagram of another embodiment of a
refrigeration system in accordance with the present invention
similar to the system of FIG. 2, but utilizing a vortex generator
in place of the expansion device;
[0031] FIG. 10 is a block diagram of another embodiment of a
refrigeration system in accordance with the present invention
utilizing a vortex generator in the condenser and a branch
connection proximate the evaporator;
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
[0032] In describing preferred embodiments of the invention,
specific terminology will be selected for the sake of clarity.
However, the invention is not intended to be limited to the
specific terms so selected, 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.
[0033] Preferred embodiments of the present invention will now be
described in detail with reference to the accompanying drawings in
which a refrigeration system in accordance with the present
invention is generally indicated at 10.
[0034] A typical refrigeration system 500 is illustrated in FIG. 1.
The refrigeration system includes a compressor 52, a condenser 54,
an expansion device 56 and an evaporator 58. The various components
are connected together via a conduit (usually copper tubing)
59.
[0035] The refrigeration system 500 is a closed loop system that
continuously circulates a refrigerant through the various elements.
The refrigerant is a condensible vapor. Some common types of
refrigerant include R-12, R-22, R-134A, R-410A, ammonia, carbon
dioxide and natural gas. The main steps in the refrigeration cycle
are compression of the refrigerant by the compressor 52, heat
rejection of the refrigerant in the condenser 54, throttling of the
refrigerant in the expansion device 56, and heat absorption of the
refrigerant in the evaporator 58. As indicated previously, this
process is referred to as the vapor compression refrigeration
cycle.
[0036] The efficiency of a refrigeration cycle (and by analogy a
heat pump cycle) depends primarily on the heat absorption from the
evaporator 58 and the efficiency of the compressor 52. The former
depends on the percentage of liquid in the liquid-vapor refrigerant
mixture before the evaporator, whereas the latter depends on the
magnitude of the pressure differential across the compressor.
[0037] A compressor is a device to increase pressure from low to
high values by compressing gas or vapor, which is usually done by
consuming electric energy. The pressure of the refrigerant as it
enters the compressor is referred to as the suction pressure level
and the pressure of the refrigerant as it leaves the compressor is
referred to as the head pressure level. Depending on the type of
refrigerant used, the head pressure can range from about 170 PSIG
(i.e., 11.6 atm) to about 450 PSIG (i.e., 30.6 atm).
[0038] Compression ratio is the term used to express the pressure
ratio between the head pressure and the suction pressure.
Compression ratio is calculated by converting the head pressure and
the suction pressure onto an absolute pressure scale and dividing
the head pressure by the suction pressure. When the compression
ratio increases, the compressor efficiency drops thereby increasing
energy consumption.
[0039] The work of a compressor, W, is mathematically defined as: 2
W = 1 2 v P
[0040] where v is specific volume, P is pressure, subscripts 1 and
2 indicate inlet (suction side) and outlet (discharge side),
respectively. As indicated by the above equation, the compressor
work is proportional to pressure differential, .DELTA.P or
P.sub.2-P.sub.1.
[0041] The compressor work in a typical refrigeration system can be
simplified for an isentropic process as: 3 W = kRT 1 k - 1 [ ( P 2
P 1 ) ( k - 1 ) / k - 1 ]
[0042] where k is a specific heat ratio, R is a gas constant, and T
is temperature. As depicted in the above equation, the compressor
work can be reduced by reducing the pressure differential,
P.sub.2-P.sub.1 or compression ratio, P.sub.2/P.sub.1 As the
compressor work is reduced, the EER (energy efficiency ratio)
increases because EER is defined as the ratio of the heat
absorption at the evaporator to compressor work.
[0043] When a compressor runs at a high compression ratio, the
compressor efficiency decreases and the compressor work increases.
As the compressor efficiency drops, more electricity is used for
less refrigeration. Furthermore, running the compressor at a high
compression ratio increases the wear and tear on the compressor and
decreases its operating life.
[0044] An evaporator 58 is made of a long coil or a series of heat
transfer panels which absorb heat from a volume of air that is
desired to be cooled. In order to absorb heat from this ambient
volume, the temperature of the refrigerant must be lower than that
of the volume to be cooled. The refrigerant exiting the expansion
device consists of low quality vapor, which is approximately 20%
vapor and 80% liquid in a typical refrigeration system.
[0045] The liquid portion of the refrigerant is used to absorb heat
from the desired volume as the liquid refrigerant evaporates inside
the evaporator. The vapor portion of the refrigerant is not
utilized to absorb heat from the ambient volume. In other words,
the vapor portion of the refrigerant does not contribute to cooling
the ambient volume and decreases the efficiency of the
refrigeration cycle.
[0046] Referring again to FIG. 2, the present invention utilizes a
vortex generator 60 between the expansion device 56 and the
evaporator 58. Vortex generator 60 converts at least a portion of
the refrigerant vapor that exits the expansion device 56 into
liquid so that it can be used in the evaporator 58 to absorb heat
from the ambient volume.
[0047] Vortex tubes are well-known in other areas of art but are
not commonly found in refrigeration systems. Vortex tubes are
specifically designed for use with non-condensible gases such as
air. Vortex tubes separate the non-condensible gas into a
relatively hot vapor stream and a relatively cool vapor stream.
[0048] A vortex generator is new and is specifically designed for
use with condensible vapors such as refrigerants. Vortex generators
are more fully disclosed and described in our co-pending U.S.
application Ser. No. 09/737,016 filed on Dec. 14, 2000 entitled
VORTEX GENERATOR. U.S. application Ser. No. 09/737,016 is hereby
incorporated by reference as if set forth fully herein; however, a
description follows.
[0049] FIG. 3A is a cross-sectional view of a "basic" vortex
generator 20 in accordance with the present invention. The vortex
generator 20 includes an elongated or longitudinal chamber 30, an
inlet 12, a nozzle 14, and an outlet 16. Its single inlet and its
single outlet usually identify this embodiment of a vortex
generator 20.
[0050] Although the longitudinal chamber 30 is shown as
substantially tubular in shape and is defined by sidewall 13, it is
believed that other designs (e.g., oval) may be utilized.
[0051] Condensible vapor enters the vortex generator 20 at inlet
12. The condensible vapor is under a high pressure (i.e.,
compressed). The nozzle 14 is fixed with respect to the sidewall 13
of the longitudinal chamber 30; there are no moving parts in the
vortex generator 20. The nozzle 14 is designed to direct the
incoming vapor in a tangential direction with respect to the
sidewall 13 of the longitudinal chamber 30.
[0052] As a result of the injection of vapor in a tangential
direction, a vortex-shaped vapor stream 25 is produced within the
longitudinal chamber 30. The vortex-shaped vapor stream 25
(sometimes referred to as cyclonic- or spiral-shaped) created by
the nozzle 14 is illustrated in FIGS. 3A and 3B. The operation of
the nozzle 14 will be more thoroughly discussed in connection with
the description of FIGS. 6A, 6B and 6C.
[0053] Referring now to FIG. 3B, near the core region 33 (i.e.,
parallel to the longitudinal axis) of the elongated chamber, a
forced vortex flow is generated, where circumferential velocity
linearly increases with the radial distance. Outwards from the core
region, there is a free vortex, where circumferential velocity
exponentially decreases along the radial distance. The vortex 25
has the general appearance of a spiral.
[0054] Referring now to FIGS. 4A and 4B, the vapor at the core
expands due to the centrifugal force, thus reducing its
temperature. In comparison, the vapor at the outer region is
compressed as the vapor is pushed toward the sidewall by the
centrifugal force, thus resulting in an increased temperature.
[0055] As condensible vapor enters a vortex generator 20, the vapor
at the core of the vortex generator 20 expands due to the vortex
flow motion of the vapor, resulting in a localized drop in
pressure. Subsequently, its temperature also drops, converting the
condensible vapor to liquid (phase change). Initially, relatively
small droplets of liquid are formed. As the phase change of the
condensible vapor occurs, the volume of the condensible vapor
shrinks because the volume of liquid is significantly smaller than
that of vapor. For example, the volume of liquid water is about
1,000 times smaller than that of water vapor (i.e., steam). For
typical refrigerants, such as R-22 and R-134a, the volume of the
liquid is approximately 80-100 times smaller than that of the
vapor.
[0056] As a result of the vapor-liquid conversion, the volume of
the condensible vapor decreases, prompting a significant drop in
the local pressure. This sudden drop in pressure is essentially the
same as what happens when the vapor suddenly expands. The sudden
drop in the pressure accompanies a corresponding temperature drop,
causing additional condensation around the initial condensed
droplet. As a result, the condensible vapor is separated into a
relatively cool liquid 38 and relatively hot vapor 39 as shown in
FIG. 5.
[0057] Referring now to FIG. 6A, an enlarged cross-sectional view
of the vortex generator 20 illustrated in FIGS. 3A and 3B is shown.
The outlet 43 may just be an open end to the longitudinal chamber;
however, as illustrated in FIG. 6A, an extension 93 may be used.
Condensible vapor enters the vortex generator at inlet 42 at one
end, and both condensed liquid and the remaining vapor exit through
the other end. The nozzle 14 is used to guide the condensible vapor
into the vortex generator tangentially at the inlet so that the
vapor can form a vortex flow in the longitudinal chamber 30 of the
vortex generator. An O-ring 98 may be used to assist in securing
the nozzle 14 within the vortex generator 20 and to ensure that all
of the condensible vapor enters the elongated chamber 30
tangentially.
[0058] The design of the nozzle 14 is shown in FIGS. 6B and 6C. A
plurality of guide vanes 48 direct the tangential entry of the
vapor into the longitudinal chamber 30 of the vortex generator.
[0059] Referring again to FIGS. 4A and 4B, the principle of the
phase-change within a vortex generator 20 is discussed. The
condensation of condensible vapor inside a vortex generator 20 may
be summarized in three steps. Step One, as illustrated in FIG. 4A,
shows the vortex flow created by a nozzle 14 at the inlet of a
vortex generator 20. Step Two, as illustrated in FIG. 4B, shows the
vapor-to-liquid phase change and the creation of a vacuum in the
core region; Step Three, also illustrated in FIG. 4B, shows the
movement of a liquid droplet from the core to the sidewall of the
vortex generator, which is the result of centrifugal force.
[0060] Liquid production as a result of a cascade effect inside a
vortex generator will now be described. Referring again to FIG. 5,
the portion of a condensible vapor is represented by region 1,
having a temperature that reaches (or drops below) its saturation
temperature due to the vortex motion near the inlet of the vortex
generator. The vapor converts to liquid in region 1, causing the
pressure in the adjacent area (indicated by 2) to drop, prompting a
temperature drop and subsequent vapor-liquid conversion.
Subsequently, the pressure in region 2 suddenly drops, and the
vapor around region 2 is affected by the vacuum, prompting further
vapor-liquid conversion. This cascade effect accelerates
vapor-liquid conversion in the vortex generator.
[0061] The cascade effect is self-sustaining once the first liquid
droplet is produced due to the vortex flow motion. In other words,
if the vortex motion cannot be maintained, then cold and hot vapor
become mixed, and the cascade effect of self-sustaining
vapor-liquid conversion stops. In summary, one has to maintain the
vortex flow structure to sustain this cascade process.
[0062] FIG. 7 illustrates an alternate embodiment of a vortex
generator 60. Vortex generator 60 has two inlets and two outlets.
The first inlet 82 is similar to the inlet of the vortex generator
20 illustrated in FIGS. 3 and 6A. The second inlet 84 is designed
to intake heated vapor refrigerant directly into the core of the
vortex generator. The second inlet 84 is sometimes referred to as a
center delivery inlet. In this vortex generator 60, the nozzle 14
will have a central opening to accommodate the second inlet 84.
[0063] At the second inlet 84, there is a vacuum produced by the
vortex flow motion of refrigerant inside the vortex generator 60.
This vacuum is sufficient enough to pull the vapor exiting from the
evaporator 58. (See FIGS. 2 and 7.) The present invention
introduces a method to recirculate or regenerate the refrigerant
vapor from evaporator 58 to vortex generator 60 using the core
vacuum created by the vortex flow motion.
[0064] The vortex generator 60 has a vapor outlet 68. The vapor
outlet 68 has a portion 69 that protrudes into the longitudinal
chamber of the vortex generator 60 in order to prevent any liquid
droplets from leaving vortex generator 60 through the vapor outlet.
The liquid outlet 76 allows the liquid to escape the vortex
generator 60.
[0065] Referring again to FIG. 2, a vortex generator 60 is placed
into the closed loop refrigeration system after the expansion
device 56. Refrigerant vapor-liquid mixture exits the expansion
device 56 and enters the vortex generator 60 at the first or
tangential inlet 82. The high pressure refrigerant mixture stream
produces a strong vortex flow in the vortex generator 60. The
vortex flow is similar in shape to a helix or spiral. The high
pressure refrigerant mixture separates into a vapor stream and a
liquid stream both moving downstream along the helical path. From
the vortex flow, the vapor stream gains a high velocity on the
order of 100 m/s.
[0066] Referring again to FIG. 2, the vortex generator 60 is also
preferably placed proximate the evaporator 58. The liquid outlet of
the vortex generator 60 is connected to the inlet of the evaporator
58. The vapor outlet 68 of the vortex generator is connected to the
inlet of diffuser 31.
[0067] The present invention utilizes a diffuser 31, as illustrated
in FIG. 2, between the vortex generator and the compressor 52. A
diffuser is a device that increases the pressure of a fluid by
slowing it down. The total energy of any fluid entering a diffuser
remains unchanged as long as there is no energy loss (i.e.,
friction) inside the diffuser. As a fluid with a high flow velocity
enters the diffuser, the total energy is made up of mostly kinetic
energy. As the fluid slows down due to the gradual increase in the
cross-sectional area of the diffuser, the kinetic energy decreases,
while the pressure the terms "mechanical" or "flow" energy are used
in thermodynamics) increases. Thus, the sum of the kinetic energy
and flow energy (i.e., pressure) is always unchanged. This is what
is known as the first law of thermodynamics or the conservation of
energy principle. In fluid mechanics, it is known as Bernoulli's
equation.
[0068] In order to make a more energy efficient refrigeration
system, we want to increase the evaporator-side pressure and
decrease the condenser-side pressure. The goal is to reduce the
compressor work. The best way to reduce the compressor work is to
reduce the pressure differential between condenser-side and
evaporator-side, which is exactly what we want to accomplish with
the diffuser.
[0069] The diffuser 31 increases the pressure of the refrigerant by
decreasing the velocity of the refrigerant before it enters the
compressor. In this manner, the suction pressure of the compressor
increases, thereby decreasing the work of the compressor, and
increasing EER. Also, this design only allows liquid refrigerant to
enter evaporator 58 thus allowing the evaporator to absorb heat
more efficiently. It should be noted that instead of a diffuser,
any means for slowing the velocity of refrigerant flow may be used;
for example, a sudden or immediate expansion of the conduit at the
same general location of the diffuser.
[0070] Referring now to FIG. 8, another refrigeration system,
similar to that disclosed in FIG. 2, is illustrated. A branch tube
68 is connected from the output of the evaporator to the inlet of
the diffuser 31. A portion of the vapor refrigerant that exits the
evaporator enters the diffuser 31 in order to increase the level of
superheat, when necessary.
[0071] In the embodiments illustrated in FIGS. 2 and 8, an increase
in the heat absorption is achieved since only the liquid
refrigerant passes through evaporator 58; this results in an
increase in efficiency (EER) of the refrigeration cycle. Diffuser
31 also ensures that the pressure differential and thus compression
ratio decrease in compressor 52; this also improves the efficiency
(EER) of the refrigeration cycle.
[0072] Referring now to FIG. 9, another refrigeration system,
similar to that disclosed in FIG. 2, is illustrated. In this
embodiment, the expansion device has been replaced with a single
inlet, single outlet vortex generator 20 similar to that
illustrated in FIG. 3. In many typical refrigeration systems, the
expansion device is a capillary tube or a thermal expansion valve.
The vortex generator 20 in this embodiment is used to throttle the
refrigerant vapor that exits the condenser 54.
[0073] Referring now to FIG. 10, another embodiment of a
refrigeration system with a modified condenser 94 is illustrated.
Since the heat rejection from the condenser to the surroundings can
occur only when the temperature of the refrigerant is greater than
that of the surroundings, the refrigerant temperature has to be
raised well above that of the surroundings. This is accomplished by
raising the pressure of the refrigerant vapor, a task that is done
by the compressor 52. Since vapor temperature is closely related to
vapor pressure, it is critically important that the condenser
efficiently rejects heat from the refrigerant to the surroundings.
If the condenser 94 is not efficient, the compressor 52 has to
further increase the head pressure in an attempt to assist the
condenser in dumping heat to the surroundings.
[0074] As illustrated in FIG. 10, another embodiment of the present
invention utilizes a vortex generator 20 in the condenser to
convert saturated refrigerant vapor to liquid thus increasing the
condenser's efficiency. The first approximately one-quarter of the
condenser is represented by 94A and the remaining approximately
three-quarters of the condenser is represented by 94B.
[0075] A condenser 54 in a "typical" refrigeration system is used
to convert superheated refrigerant vapor to liquid by rejecting
heat to the surroundings. The condenser is a long heat transfer
coil or series of heat rejecting panels similar in appearance to
the evaporator. As refrigerant enters a "typical" condenser, the
superheated vapor first becomes saturated vapor in the
approximately first quarter-section of the condenser, and the
saturated vapor undergoes a phase change in the remainder of the
condenser at approximately constant pressure.
[0076] In this embodiment of the invention, the vortex generator 20
is inserted approximately one-quarter of the way into the condenser
94 (i.e., at the point where the superheated vapor becomes
saturated vapor in full or in part). By inserting the vortex
generator 20 in an existing condenser, manufacturing costs of the
installation of the vortex generator 20 may be minimized. However,
for all intents and purposes two separate condensers, each about
the respective size of condenser portions 94A and 94B, may be
used.
[0077] When a vortex generator 20 is placed approximately
one-fourth of the way from the inlet of the condenser, the
temperature of the refrigerant does not have to be raised well over
that of the surroundings thus allowing the compressor to run at a
lower head pressure than would be the case without the vortex
generator 20.
[0078] Since the refrigerant vapor becomes saturated or subcooled
liquid at the output of the condenser, the size of the condenser in
prior art refrigeration systems is often chosen larger than
necessary in order to ensure the exchange of heat. The present
method allows the size of the condenser 94 to be reduced because
the substantial amount of saturated refrigerant vapor is converted
to liquid by the vortex generator 20. The present invention allows
the use of a smaller condenser than is the case without a vortex
generator 20 thereby reducing the size of air conditioning systems,
refrigerators and heat pumps.
[0079] FIG. 10 also illustrates the use of valve 81 located on the
branch tube 68 to control the flow of vapor refrigerant from the
evaporator to the diffuser 31.
[0080] Although this invention has been described and illustrated
by reference to specific embodiments, it will be apparent to those
skilled in the art that various changes and modifications may be
made which clearly fall within the scope of this invention. The
present invention is intended to be protected broadly within the
spirit and scope of the appended claims. +C
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