U.S. patent application number 12/380792 was filed with the patent office on 2009-09-17 for vapor compression refrigerating cycle apparatus.
This patent application is currently assigned to DENSO CORPORATION. Invention is credited to Mika Gocho, Hideya Matsui, Haruyuki Nishijima, Gouta Ogata, Etsuhisa Yamada.
Application Number | 20090229306 12/380792 |
Document ID | / |
Family ID | 41011386 |
Filed Date | 2009-09-17 |
United States Patent
Application |
20090229306 |
Kind Code |
A1 |
Yamada; Etsuhisa ; et
al. |
September 17, 2009 |
Vapor compression refrigerating cycle apparatus
Abstract
A vapor compression refrigerating cycle apparatus includes a
compressor, a radiator, a first decompressing device, a second
decompressing device, a flow distributor, an ejector, and a
suction-side evaporator. The vapor compression refrigerating cycle
apparatus is configured such that refrigerant pressure (P0) at an
inlet of the first decompressing device, refrigerant pressure (P)
at an inlet of a nozzle portion of the ejector, refrigerant
pressure (P2) at an outlet of the nozzle portion satisfy a pressure
relationship of
0.1.times.(P0-P2).ltoreq.(P0-P).ltoreq.0.6.times.(P0-P2).
Alternative to or in addition to the pressure relationship, the
vapor compression refrigerating cycle apparatus is configured such
that a dryness of refrigerant at the inlet of the nozzle portion is
in a range between 0.003 and 0.14.
Inventors: |
Yamada; Etsuhisa;
(Kariya-city, JP) ; Nishijima; Haruyuki;
(Obu-city, JP) ; Ogata; Gouta; (Nisshin-city,
JP) ; Gocho; Mika; (Obu-city, JP) ; Matsui;
Hideya; (Kariya-city, JP) |
Correspondence
Address: |
HARNESS, DICKEY & PIERCE, P.L.C.
P.O. BOX 828
BLOOMFIELD HILLS
MI
48303
US
|
Assignee: |
DENSO CORPORATION
Kariya-city
JP
|
Family ID: |
41011386 |
Appl. No.: |
12/380792 |
Filed: |
March 4, 2009 |
Current U.S.
Class: |
62/500 ;
62/515 |
Current CPC
Class: |
F25B 41/00 20130101;
F25B 2500/19 20130101; F25B 2341/0011 20130101; F25B 40/00
20130101 |
Class at
Publication: |
62/500 ;
62/515 |
International
Class: |
F25B 1/06 20060101
F25B001/06; F25B 39/02 20060101 F25B039/02 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 13, 2008 |
JP |
2008-064665 |
Claims
1. A vapor compression refrigerating cycle apparatus comprising: a
compressor that draws and compresses refrigerant; a radiator that
radiates heat of refrigerant discharged from the compressor; a
first decompressing device that decompresses refrigerant downstream
of the radiator; a flow distributor that separates refrigerant
decompressed by the first decompressing device into at least a
first flow and a second flow; an ejector that includes a nozzle
portion and a suction portion, the nozzle portion that draws
refrigerant of the first flow and decompresses and expands the
refrigerant of the first flow to generate a refrigerant jet flow,
the suction portion that draws refrigerant of the second flow by
the refrigerant jet flow from the nozzle portion; a second
decompressing device that decompresses the refrigerant of the
second flow; and a suction-side evaporator that evaporates
refrigerant decompressed by the second decompressing device and
discharges evaporated refrigerant toward the suction portion of the
ejector, wherein it is configured that refrigerant pressure (P0) at
an inlet of the first decompressing device, refrigerant pressure
(P) at an inlet of the nozzle portion, refrigerant pressure (P2) at
an outlet of the nozzle portion satisfy a pressure relationship of
0.1.times.(P0-P2).ltoreq.(P0-P).ltoreq.0.6.times.(P0-P2).
2. The vapor compression refrigerating cycle apparatus according to
claim 1, wherein it is configured that the refrigerant at an inlet
of the nozzle portion has a dryness in a range between 0.003 and
0.14.
3. The vapor compression refrigerating cycle apparatus according to
claim 2, wherein the flow distributor has a distribution rate
adjusting part that adjusts flow rates of the first and second
flows, and the dryness of the refrigerant is adjusted by the
distribution rate adjusting part.
4. The vapor compression refrigerating cycle apparatus according to
claim 1, wherein the pressure relationship is achieved by adjusting
a throttle degree of at least one of the first decompressing
device, the second decompressing device and the nozzle portion of
the ejector.
5. The vapor compression refrigerating cycle apparatus according to
claim 1, further comprising: a discharge-side evaporator that
evaporates refrigerant discharged from the ejector.
6. The vapor compression refrigerating cycle apparatus according to
claim 1, further comprising: an internal heat exchanger that
performs heat exchange between refrigerant discharged from the
radiator and refrigerant discharged from the ejector.
7. A vapor compression refrigerating cycle apparatus comprising: a
compressor that draws and compresses refrigerant; a radiator that
radiates heat of refrigerant discharged from the compressor; a
first decompressing device that decompresses refrigerant downstream
of the radiator; a flow distributor that separates refrigerant
decompressed by the first decompressing device into at least a
first flow and a second flow; an ejector that includes a nozzle
portion and a suction portion, the nozzle portion that draws
refrigerant of the first flow and decompresses and expands the
refrigerant of the first flow to generate a refrigerant jet flow,
the suction portion that draws refrigerant of the second flow by
the refrigerant jet flow from the nozzle portion; a second
decompressing device that decompresses the refrigerant of the
second flow; and a suction-side evaporator that evaporates
refrigerant decompressed by the second decompressing device and
discharges evaporated refrigerant toward the suction portion of the
ejector, wherein it is configured that the refrigerant at an inlet
of the nozzle portion has a dryness in a range between 0.003 and
0.14.
8. The vapor compression refrigerating cycle apparatus according to
claim 7, wherein the flow distributor has a distribution rate
adjusting part that adjusts flow rates of the first and second
flows, and the dryness of the refrigerant is adjusted by the
distribution rate adjusting part.
9. The vapor compression refrigerating cycle apparatus according to
claim 7, further comprising: a discharge-side evaporator that
evaporates refrigerant discharged from the ejector.
10. The vapor compression refrigerating cycle apparatus according
to claim 7, further comprising: an internal heat exchanger that
performs heat exchange between refrigerant discharged from the
radiator and refrigerant discharged from the ejector.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is based on Japanese Patent Application No.
2008-64665 filed on Mar. 13, 2008, the disclosure of which is
incorporated herein by reference.
FIELD OF THE INVENTION
[0002] The present invention relates to a vapor compression
refrigerating cycle apparatus having an ejector as a refrigerant
decompressing and circulating device.
BACKGROUND OF THE INVENTION
[0003] A vapor compression refrigerating cycle apparatus is, for
example, described in JP-A-2007-23966 (US2006/0266072 A1). The
described refrigerating cycle apparatus has an ejector as a
decompressing device for decompressing condensed refrigerant and
two evaporators. The ejector generally has a nozzle portion, a
suction portion, a mixing portion and a pressure-increase
portion.
[0004] The nozzle portion draws a part of the refrigerant
downstream of a radiator, and decompresses and expands the drawn
refrigerant in an isenthalpic manner. The suction portion draws a
remaining part of the refrigerant from one of the evaporators. The
part of the refrigerant is jetted from the nozzle portion at high
velocity, and is mixed with the remaining part of the refrigerant
drawn from the suction portion. Further, the mixed refrigerant is
increased in pressure through the pressure-increase portion, and is
then discharged from the ejector. The refrigerant is further
conducted to the other evaporator to be evaporated, and is then
drawn into the compressor.
SUMMARY OF THE INVENTION
[0005] In such a vapor compression refrigerating cycle apparatus,
in a case where refrigerant drawn into a nozzle portion of an
ejector is in a gas and liquid two-phase condition, it is difficult
to improve ejector efficiency while appropriately controlling the
flow rate of the refrigerant at the nozzle portion. As such, it is
difficult to stably maintain a coefficient of performance (COP) of
the refrigerating cycle apparatus at a sufficient level.
[0006] The present invention is made in view of the foregoing
matter, and it is an object of the present invention to provide a
vapor compression refrigerating cycle apparatus capable of
controlling a condition of refrigerant at the nozzle portion of the
ejector to a predetermined condition, thereby to maintain the COP
at the sufficient level.
[0007] According to a first aspect of the present invention, a
vapor compression refrigerating cycle apparatus includes a
compressor, a radiator, first and second decompressing devices, a
flow distributor, an ejector and a suction-side evaporator. The
compressor draws and compresses refrigerant. The radiator radiates
heat of refrigerant discharged from the compressor. The first
decompressing device decompresses refrigerant discharged from the
radiator. The flow distributor separates refrigerant decompressed
by the first decompressing device into at least a first flow and a
second flow. The ejector includes a nozzle portion and a suction
portion. The nozzle portion draws refrigerant of the first flow,
and decompresses and expands the refrigerant of the first flow to
generate a refrigerant jet flow. The suction portion draws
refrigerant of the second flow by the refrigerant jet flow from the
nozzle portion. The second decompressing device decompresses the
refrigerant of the second flow. The suction-side evaporator
evaporates refrigerant decompressed by the second decompressing
device and discharges evaporated refrigerant toward the suction
portion of the ejector. Further, the vapor compression
refrigerating cycle apparatus is configured such that refrigerant
pressure (P0) at an inlet of the first decompressing device,
refrigerant pressure (P) at an inlet of the nozzle portion,
refrigerant pressure (P2) at an outlet of the nozzle portion
satisfy a pressure relationship of
0.1.times.(P0-P2)>(P0-P).ltoreq.0.6.times.(P0-P2):
[0008] Accordingly, because the refrigerant pressure at the inlet
of the nozzle portion becomes an optimum condition, a distribution
ratio of the refrigerant to the suction-side evaporator and the
nozzle portion can be set to an optimum ratio. Therefore, capacity
of the suction-side evaporator and nozzle efficiency are both
improved. As such, the COP of the vapor compression refrigerating
cycle apparatus improves. For example, the pressure relationship is
achieved by adjusting a throttle degree of at least one of the
first decompressing device, the second decompressing device and the
nozzle portion.
[0009] According to a second aspect of the present invention, a
vapor compression refrigerating cycle apparatus includes a
compressor, a radiator, first and second decompressing devices, a
flow distributor, an ejector and a suction-side evaporator. The
compressor draws and compresses refrigerant. The radiator radiates
heat of refrigerant discharged from the compressor. The first
decompressing device decompresses refrigerant discharged from the
radiator. The flow distributor separates refrigerant decompressed
by the first decompressing device into at least a first flow and a
second flow. The ejector includes a nozzle portion and a suction
portion. The nozzle portion draws refrigerant of the first flow,
and decompresses and expands the refrigerant of the first flow to
generate a refrigerant jet flow. The suction portion draws
refrigerant of the second flow by the refrigerant jet flow from the
nozzle portion. The second decompressing device decompresses the
refrigerant of the second flow. The suction-side evaporator
evaporates refrigerant decompressed by the second decompressing
device and discharges evaporated refrigerant toward the suction
portion of the ejector. Further, the vapor compression
refrigerating cycle apparatus is configured such that the
refrigerant at an inlet of the nozzle portion has a dryness in a
range between 0.003 and 0.14.
[0010] Accordingly, because the dryness of the refrigerant at the
inlet of the nozzle portion is controlled to an optimum condition,
a distribution ratio of the refrigerant to the suction-side
evaporator and the nozzle portion can be set to an optimum ratio.
Therefore, capacity of the suction-side evaporator and nozzle
efficiency are both improved. As such, the COP of the vapor
compression refrigerating cycle apparatus improves.
BRIEF DESCRIPTION OF THE DRAWINGS
[0011] Other objects, features and advantages of the present
invention will become more apparent from the following detailed
description made with reference to the accompanying drawings, in
which like parts are designated by like reference numbers and in
which:
[0012] FIG. 1 is a schematic block diagram of a vapor compression
refrigerating cycle apparatus according to an embodiment of the
present invention;
[0013] FIG. 2 is a graph showing a relationship between enthalpy
and pressure in the vapor compression refrigerating cycle apparatus
according to the embodiment;
[0014] FIG. 3 is a graph showing an operation of the vapor
compression refrigerating cycle apparatus according to the
embodiment;
[0015] FIG. 4 is a graph showing a relationship between refrigerant
pressure and a COP improvement effect of the vapor compression
refrigerating cycle apparatus according to the embodiment;
[0016] FIG. 5 is a graph showing a relationship between dryness of
refrigerant at an inlet of a nozzle portion of an ejector and the
COP improvement effect of the vapor compression refrigerating cycle
apparatus according to the embodiment;
[0017] FIG. 6 is a schematic block diagram of a vapor compression
refrigerating cycle apparatus according to another embodiment of
the present invention; and
[0018] FIG. 7 is a graph showing a relationship between enthalpy
and pressure in the vapor compression refrigerating cycle apparatus
shown in FIG. 6.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0019] An exemplary embodiment of the present invention will now be
described with reference to FIGS. 1 to 5. FIG. 1 shows an example
of a vapor compression refrigerating cycle apparatus 10 of the
present embodiment. The refrigerating cycle apparatus 10 is an
ejector-type refrigerating cycle apparatus including an ejector 5,
which serves as a decompressing device for decompressing
refrigerant and a pump for transporting the refrigerant. The
refrigerating cycle apparatus 10 is, for example, employed in a
vehicle refrigerating unit, a vehicle air conditioner and the
like.
[0020] The refrigerating cycle apparatus 10 generally includes a
compressor 1, a radiator 2, a first decompressing device 3, an
ejector 5, a flow distributor 6, a second decompressing device 4
and a suction-side evaporator 8. In the example shown in FIG. 1,
the refrigerating cycle apparatus 10 further includes a
discharge-side evaporator 7. The compressor 1, the radiator 2, the
first decompressing device 3, the ejector 5, the flow distributor 6
and the discharge-side evaporator 7 (hereinafter, referred to as
the first evaporator 7) are connected in a form of loop through
pipes.
[0021] The flow distributor 6 distributes the refrigerant, which
has been decompressed through the first decompressing device 3 into
a first flow that is in communication with a nozzle portion 5a of
the ejector 5 and a second flow that is in communication with a
suction portion 5b of the ejector 5 through a branch passage 9.
That is, the branch passage 9 diverges from the flow distributor 6
and connects to the suction portion 5b of the ejector 5. The second
decompressing device 4 and the suction-side evaporator 8
(hereinafter, referred to as the second evaporator 8) are disposed
on the branch passage 9.
[0022] The compressor 1 draws and compresses refrigerant. The
compressor 1 discharges high pressure refrigerant toward the
radiator 2. The compressor 1 is driven by a vehicle engine through
an electromagnetic clutch, a pulley, and a belt. The compressor 1
is any-types of compressor, such as, a variable capacity-type
compressor that is capable of adjusting a discharge rate in
accordance with a change in discharge capacity, a fixed
capacity-type compressor that is capable of adjusting a discharge
rate in accordance with a change in a rate of operation thereof by
on and off operations of the electromagnetic clutch, an electric
compressor that is capable of adjusting a discharge rate by
controlling a rotation speed of an electric motor, or the like.
[0023] The radiator 2 is disposed downstream of the compressor 1
with respect to a flow of refrigerant. The radiator 2 performs heat
exchange between the high pressure refrigerant discharged from the
compressor 1 and air, thereby to condense the refrigerant. The air
is, for example, outside air drawn from an outside of a passenger
compartment of a vehicle and forcibly applied to the radiator 2
such as by a blower (not shown).
[0024] Here, the refrigerant is not limited to a specific
refrigerant. In the present embodiment, for example, the
refrigerant is R404A. In a case where a chlorofluorocarbon-base
refrigerant, such as R404A, is used, the refrigerating cycle
apparatus is operated under a subcritical condition where pressure
on a high-pressure side does not exceed the critical pressure.
[0025] In this case, therefore, the radiator 2 serves as a
condenser for condensing the refrigerant therein. In a case where
carbon dioxide is used as the refrigerant, the refrigerating cycle
apparatus is operated under a supercritical condition where
pressure on the high-pressure side exceeds the critical pressure.
In this case, the refrigerant radiates heat while maintaining in a
supercritical condition, and thus is not condensed.
[0026] The first decompressing device 3 serves to decompress the
high pressure refrigerant having passed through the radiator 2. The
first decompressing device 3 is, for example, an expansion
valve.
[0027] The expansion valve 3 is, for example, a temperature
operation-type in which a valve opening degree is controlled to
adjust a superheat degree to a predetermined condition based on a
temperature of refrigerant at an outlet of the first evaporator
7.
[0028] Alternatively, the first decompressing device 3 can be a
fixed flow control valve, an electric controlled flow control valve
in which a refrigerant flow rate is variably controlled, or the
like.
[0029] The high pressure refrigerant is decompressed into a gas and
liquid two-phase condition by controlling a decompressing rate
through the first decompressing device 3, and is then conducted to
the flow distributor 6. Here, the gas and liquid two-phase
refrigerant forms stratified flow, linear flow, slag flow, and the
like in accordance with dryness, velocity and the like. Further,
the gas and liquid two-phase refrigerant forms an upper and lower
separated flow in which gas-phase refrigerant is located above
liquid refrigerant.
[0030] The flow distributor 6 is a block member having such as a
cubic shape and a rectangular parallelepiped shape. The flow
distributor 6 is formed with multiple passages therein, and serves
to distribute the refrigerant decompressed through the first
decompressing device 3 into at least two flows at predetermined
rates.
[0031] The flow distributor 6 at least has a first passage that is
in communication with the first decompressing device 3, a second
passage diverging from the first passage and connecting to the
branch passage 9 for conducting the refrigerant toward the second
evaporator 8, and a third passage diverging from the first passage
and is in communication with the nozzle portion 5a of the ejector
5. The first to third passages constitute a distribution rate
adjusting part.
[0032] Each of the first to third passages has a predetermined
shape and a passage area (cross-sectional area) and is located at a
predetermined position, such as a predetermined height. For
example, the passage areas of the first to third passages satisfy a
predetermined relationship. Therefore, the flow rate of refrigerant
passing through each passage, the volume of liquid-phase
refrigerant passing through each passage and the like are
determined in accordance with pressure condition of the
refrigerant. Further, the low distributor 6 can be provided with a
valve device to vary the flow rates of the refrigerant passing
through the respective passages.
[0033] The ejector 5 serves as a decompressing device for
decompressing refrigerant and a circulating device for circulating
the refrigerant by means of a drawing effect (dragging effect)
generated by a jet flow of refrigerant. The ejector 5 generally has
the nozzle portion 5a, the suction portion 5b, a mixing portion 5c
and a diffuser portion 5d.
[0034] The nozzle portion 5a is in communication with the third
passage of the flow distributor 6. The nozzle portion 5a draws the
refrigerant of the first flow from the flow distributor 6, and
decompresses and expands the refrigerant in an isenthalpic manner
by reducing a passage area therein. The suction portion 5b is
disposed to be in communication with a jet port of the nozzle
portion 5a. The suction portion 5b draws gas-phase refrigerant from
the second evaporator 8.
[0035] The mixing portion 5c mixes the refrigerant jetted from the
jet port of the nozzle portion 5a at high velocity with the
refrigerant drawn from the suction portion 5b. The diffuser portion
5d is disposed downstream of the mixing portion 5c. The diffuser
portion 5d is configured such that a passage area gradually reduces
to reduce the velocity of the refrigerant and increase the
refrigerant in pressure. That is, the diffuser portion 5d has a
function of converting velocity energy of the refrigerant into
pressure energy. Therefore, the diffuser portion 5d can be also
referred to as a pressure-increase portion.
[0036] Accordingly, in the ejector 5, pressure is rapidly reduced
in the nozzle portion 5a, and is the lowest at the outlet of the
nozzle portion 5a. Since the refrigerant decompressed in the nozzle
portion 5a is mixed with the refrigerant drawn from the suction
portion 5b in the mixing portion 5c, the pressure gradually
increases. The pressure is then increased in the diffuser portion
5d due to the decrease in velocity.
[0037] The first evaporator 7 is disposed downstream of the
diffuser portion 5d with respect to the flow of refrigerant. The
first evaporator 7 is a heat absorber that performs heat exchange
between the refrigerant discharged from the ejector 5 and air,
which is forcibly applied to the first evaporator 7, thereby to
achieve a heat absorbing effect due to evaporation of the
refrigerant. A discharge side of the first evaporator 7 is in
communication with a suction side of the compressor 1.
[0038] The second decompressing device 4 is, for example,
constructed of a capillary tube, such as a spiral tubule. The
second decompressing device 4 is disposed on the branch passage 9.
The second decompressing device 4 serves to decompress refrigerant
flowing in the second evaporator 8 and control a flow rate of the
refrigerant. The second decompressing device 4 can be a variable
decompressing device such as an electric control expansion valve,
in place of the capillary tube.
[0039] The second evaporator 8 is disposed on the branch passage 9
downstream of the second decompressing device 4 with respect to the
flow of refrigerant. The second evaporator 8 is a heat absorber,
similar to the first evaporator 7. That is, the second evaporator 8
achieves a heat absorbing effect by evaporating the
refrigerant.
[0040] For example, the second evaporator 8 is located downstream
of the first evaporator 7 with respect to the flow of air. Thus,
the air having passed through the first evaporator 7 is further
cooled while passing through the second evaporator 8 by exchanging
heat with the refrigerant flowing inside of the second evaporator
8. Then, the air is conducted to a predetermined space, such as for
an air conditioning operation.
[0041] Alternatively, the first evaporator 7 and the second
evaporator 8 are provided differently. For example, airs can be
applied separately to the first evaporator 7 and the second
evaporator 8 by blowers and the like, and the airs can be conducted
to different spaces to be air-conditioned.
[0042] The first evaporator 7 and the second evaporator 8 can be
constructed separately from each other. Alternatively, the first
evaporator 7 and the second evaporator 8 can be integrated with
each other. In a case where the first evaporator 7 and the second
evaporator 8 are integrated with each other, the first evaporator 7
and the second evaporator 8 can be joined with each other by
brazing. In this case, components of the first evaporator 7 and the
second evaporator 8 are made of aluminum, for example. Further, the
flow distributor 6, the second decompressing device 4 and the
ejector 5 can be integrated with each other into a unit, and
further fixed to the first and second evaporators 7, 8.
[0043] The vapor compression refrigerating cycle apparatus 10 can
be further provided with an internal heat exchanger to perform heat
exchange between the high pressure refrigerant flowing between the
radiator 2 and the first decompressing device 3 and low pressure
refrigerant to be drawn to the compressor 1. In this case, the high
pressure refrigerant flowing between the radiator 2 and the
expansion valve 3 is cooled by the heat exchange with the low
pressure refrigerant. As such, enthalpy differential between
refrigerant inlets and refrigerant outlets of the first evaporator
7 and the second evaporator 8 increases, and thus cooling capacity
improves.
[0044] For example, an operation of the compressor 1 is controlled
by a control unit (not shown). The control unit is constructed of a
microcomputer including a CPU, a ROM, a RAM and the like and
peripheral circuits. The control unit executes various computations
and processing in accordance with control programs stored in the
ROM to control operations of various devices including the
compressor 1.
[0045] The control unit receives detection signals from various
sensors and various manipulation signals from an operation panel
(not shown). For example, the operation panel is provided with a
temperature setting switch for setting a cooling temperature of a
space to be cooled and an air conditioner operation switch for
generating an operation command signal of the compressor 1.
[0046] Next, an operation of the vapor compression refrigerating
cycle apparatus 10 will be described with reference to FIG. 2. In
FIG. 2, points a1 through i1 correspond to locations a1 through i1
in FIG. 1.
[0047] When the electromagnetic clutch of the compressor 1 is
electrically conducted in accordance with the signal generated from
the control unit, the electromagnetic clutch becomes in a connected
state and a driving force is transmitted from an engine of a
vehicle to the compressor 1. When the operation of the compressor 1
is started, the gas-phase refrigerant is drawn into the compressor
1 from the first evaporator 7 and compressed in the compressor 1.
The high temperature, high pressure refrigerant at a flow rate G
(=Gn+Ge) is discharged from the compressor 1 toward the radiator 2.
(g1.fwdarw.a1)
[0048] In the radiator 2, the high temperature, high pressure
refrigerant is condensed by being cooled by the air.
(a1.fwdarw.b1)
[0049] High pressure liquid-phase refrigerant flowing out from the
radiator 2 at the flow rate G is decompressed and expanded into
predetermined pressure by the first decompressing device 3. Thus,
the gas and liquid two-phase refrigerant is generated. Here,
refrigerant pressure at an inlet of the first decompressing device
3 is defined as P0.
[0050] The gas and liquid two-phase refrigerant flowing out from
the first decompressing device 3 flows in the flow distributor 6.
In the flow distributor 6, the gas and liquid two-phase refrigerant
is separated into the first flow passing through the third passage
toward the nozzle portion 5a of the ejector 5 (b1.fwdarw.c1) and
the second flow passing through the second passage toward the
second decompressing device 4 (b1.fwdarw.h1), at predetermined flow
rates. Here, the flow rate of the refrigerant of the first flow is
defined as Gn, and the flow rate of the refrigerant of the second
flow is defined as Ge. Refrigerant pressure at an inlet of the
nozzle portion 5a is defined as P.
[0051] The refrigerant flows in the nozzle portion 5a of the
ejector 5 at the flow rate Gn from the first flow. In the ejector
5, the refrigerant is decompressed and expanded in the isenthalpic
manner through the nozzle portion 5a. (c1.fwdarw.d1). Thus, the
refrigerant pressure P reduces to refrigerant pressure P2 at the
outlet of the nozzle portion 5a. That is, in the nozzle portion 5a,
pressure energy of the refrigerant is converted into velocity
energy, and thus the refrigerant is jetted from the jet port of the
nozzle portion 5a at high velocity. At this time, the gas-phase
refrigerant of the flow rate Ge is drawn from the second evaporator
8 into the suction portion 5b by the drawing effect generated by
the jet flow of the refrigerant.
[0052] The refrigerant jetted from the nozzle portion 5a and the
refrigerant drawn into the suction portion 5b are mixed with each
other in the mixing portion 5c (d1.fwdarw.e1, i1.fwdarw.e1), and
then introduced in the diffuser portion 5d. In the diffuser portion
5d, since the passage area is gradually increased, velocity
(expansion) energy of the refrigerant is converted into pressure
energy. Thus, the refrigerant is increased in pressure
(e1.fwdarw.f1).
[0053] The refrigerant flowing out from the diffuser portion 5d at
the flow rate G flows in the first evaporator 7. In the first
evaporator 7, the low temperature, low pressure refrigerant is
evaporated in a heat exchanging core portion by absorbing heat from
the air (f1.fwdarw.g1). Pressure of the low temperature, low
pressure refrigerant is defined as P1. The gas-phase refrigerant
evaporated in the first evaporator 1 is drawn by the compressor 1
and is compressed again.
[0054] On the other hand, the refrigerant of the second flow is
conducted in the branch passage 9 at the flow rate Ge and
decompressed into the low pressure refrigerant by the second
decompressing device 4 (b1.fwdarw.h1). The low pressure refrigerant
is then conducted to the second evaporator 8. In the second
evaporator 8, the low pressure refrigerant is evaporated by
absorbing heat from the air (h1.fwdarw.i1), and becomes the
gas-phase refrigerant. The gas-phase refrigerant is drawn into the
suction portion 5b at the flow rate Ge.
[0055] Accordingly, the refrigerant of the flow rate Gn is supplied
to the first evaporator 7 and the refrigerant of the flow rate Ge
is supplied to the second evaporator 8 through the second
decompressing device 4. Therefore, cooling effects are achieved
simultaneously by the first and second evaporators 7, 8.
[0056] In the present embodiment, the first decompressing device 3,
the second decompressing device 4 and the nozzle portion 5a have
predetermined throttle degrees such that the refrigerant pressure
P0 at the inlet of the first decompressing device 3, the
refrigerant pressure P at the inlet of the nozzle portion 5a and
the refrigerant pressure P2 at the outlet of the nozzle portion 5a
satisfy the following pressure relationship (R1):
0.1.times.(P0-P2).ltoreq.P.ltoreq.0.6.times.(P0-P2) (R1)
[0057] That is, the vapor compression refrigerating cycle apparatus
10 is configured such that a decrease in pressure, that is, a
differential pressure between the refrigerant pressure P0 at the
inlet of the first decompressing device 3 and the refrigerant
pressure P at the inlet of the nozzle portion 5a is equal to a
value that is obtained by multiplying a differential pressure
between the inlet of the first decompressing device 3 and the
outlet of the nozzle portion 5a by a value that is at least 0.1 and
at most 0.6.
[0058] In FIG. 2, .sub..DELTA.P represents an increase in pressure
by the ejector 5, such as by the diffuser portion 5d. That is,
.sub..DELTA.P is a differential pressure (P1-P2) between the
refrigerant pressure P1 flowing in the first evaporator 7 and a
refrigerant evaporation pressure P2 in the second evaporator 8.
Because suction pressure of the compressor 1 is increased by an
effect of increasing in pressure by the diffuser portion 5d, which
is represented by .sub..DELTA.P, the driving force of the
compressor 1 can be reduced. As a result, the COP of the vapor
compression refrigerating cycle apparatus 10 improves.
[0059] As shown in FIG. 2, the refrigerant evaporation pressure P2
of the second evaporator 8 is lower than the refrigerant
evaporation pressure P1 of the first evaporator 7. Therefore, a
refrigerant evaporation temperature of the second evaporator 8 is
lower than a refrigerant evaporation temperature of the first
evaporator 7.
[0060] In the case where the first evaporator 7 is disposed
upstream of the second evaporator 8 with respect to the flow of
air, it is possible to ensure both a temperature differential
between the refrigerant evaporation temperature of the first
evaporator 7 and the air and a temperature differential between the
refrigerant evaporation temperature of the second evaporator 8 and
the air. Accordingly, cooling performances of both the first and
second evaporators 7, 8 effectively improve.
[0061] FIG. 3 shows relationships between differential pressure at
inlets and outlets of flow rate control devices, such as the first
decompressing device 3, the second decompressing device 4 and the
nozzle portion 5a, and the flow rates at the respective
portions.
[0062] As shown in FIG. 3, the flow rate G of the first
decompressing device 3 increases as the refrigerant pressure P at
the inlet of the nozzle portion 5a reduces, that is, as the
differential pressure (P0-P) between the refrigerant pressure P0 of
the inlet of the first decompressing device 3 and the refrigerant
pressure P of the inlet of the nozzle portion 5a increases. In this
case, the differential pressure between the inlet and the outlet of
each of the nozzle portion 5a and the second decompressing device 4
reduces. As such, each of the flow rates Gn, Ge reduces. Further,
the refrigerant pressure P at the inlet of the nozzle portion 5a is
determined to pressure where the flow rate G of the first
decompressing device 3 is equal to the sum of the flow rate Gn of
the nozzle portion 5a and the flow rate Ge of the second
decompressing device 4.
[0063] Further, a ratio of the flow rates Gn, Ge is determined
based on a flow rate property by the differential pressure between
the inlet and the outlet of the nozzle portion 5a and a flow rate
property by the differential pressure between the inlet and the
outlet of the second decompressing device 4. Further, expansion
energy recovered at the nozzle portion 5a reduces as the
refrigerant pressure P at the inlet of the nozzle portion 5a
reduces. As such, the increase in pressure .sub..DELTA.P by the
ejector 5 reduces.
[0064] Accordingly, in view of ensuring the performance of the
evaporators 7, 8 and nozzle efficiency, it is preferable to set the
ratio of the flow rates Gn, Ge to an optimum ratio as discussed
hereinabove, and it is recognized that there is an optimum
condition of the refrigerant pressure at the inlet of the nozzle
portion 5a. Further, it is realized that the nozzle efficiency is
sufficient when the pressure relationship (R1) is satisfied because
the pressure condition at the inlet of the nozzle portion 5a is
under the optimum condition. Moreover, it is realized that the
refrigerating capacity (COP) is sufficiently achieved in a range of
the refrigerant flow rate ratio, which is obtained when the
pressure relationship (R1) is satisfied. The range of the
refrigerant flow rate ratio corresponds to a nondimensional flow
rate ratio (Ge/(Ge+Gn)).
[0065] FIG. 4 shows a relationship between a pressure ratio
(P0-P)/(P0-P2) and a COP improvement effect. The pressure ratio
(P0-P)/(P0-P2) is a ratio of the decrease in the refrigerant
pressure P at the inlet of the nozzle portion 5a with respect to
the refrigerant pressure P0 at the inlet of the first decompressing
device 3 to the decrease in refrigerant pressure P2 at the outlet
of the nozzle portion 5a with respect to the refrigerant pressure
P0 at the inlet of the first decompressing device 3.
[0066] Here, the COP improvement effect is the improvement of the
COP of the vapor compression refrigerating cycle apparatus 10 with
respect to the COP of an expansion valve cycle apparatus. That is,
the higher the value indicative of the COP improvement effect is,
the more the COP of the vapor compression refrigerating cycle
apparatus 10 is improved, as compared with the COP of the expansion
valve cycle apparatus. The expansion valve cycle apparatus is a
refrigerating cycle apparatus constructed by sequentially
connecting the compressor, the radiator, the expansion valve and
the evaporator in a form of closed circuit.
[0067] According to the graph of FIG. 4, the COP improvement effect
is low in regions where the pressure ratio (P0-P)/(P0-P2) is small
and large. Further, the COP improvement effect is high in a middle
region between the regions. Particularly, when the pressure ratio
(P0-P)/(P0-P2) is in a range between 0.1 and 0.6, the COP
improvement effect is stable and at the highest level. That is, the
pressure ratio (P0-P)/(P0-P2) is the optimum in the range between
0. and 0.6.
[0068] This is based on the following reasons. Since the
refrigerant evaporation temperature of the second evaporator 8 is
lower than the refrigerant evaporation temperature of the first
evaporator 7, refrigerating capacity Qer of the entirety of the
refrigerating cycle apparatus is increased by increasing the flow
rate Ge of the refrigerant passing through the second evaporator 8.
Thus, the COP improves. However, the flow rate Gn of the
refrigerant passing through the nozzle portion 5a reduces with an
increase in the flow rate Ge. As a result, the increase in pressure
.sub..DELTA.P by the ejector 5 reduces.
[0069] Accordingly, when the flow rate Ge is excessively increased,
the driving force L of the compressor 1 is excessively increased.
As a result, the COP (Qer/L), which is obtained by a ratio of the
refrigerating capacity Qer of the entirety of the refrigerating
cycle apparatus to the driving force L of the compressor 1,
reduces.
[0070] According to FIGS. 3 and 4, it is found that when the
pressure relationship (R1) is satisfied, the COP of the
refrigerating cycle apparatus 10 is sufficiently improved, as
compared with the COP of the expansion valve cycle. Accordingly,
the COP is ensured at a sufficient level.
[0071] For example, the pressure relationship (R1) is achieved by
constructing the first decompressing device 3, the second
decompressing device 4 and the ejector 5 to have the predetermined
throttle degrees, respectively.
[0072] When the pressure relationship (R1) is satisfied, the
refrigerant at the inlet of the nozzle portion 5a is controlled
under a predetermined pressure condition. Accordingly, the COP is
sufficiently ensured.
[0073] FIG. 5 is a graph showing a relationship between dryness X
of the refrigerant at the inlet of the nozzle portion 5a and the
COP improvement effect of the vapor compression refrigerating cycle
apparatus 10.
[0074] The dryness X is a ratio of vapor in 1 kg wet vapor of the
refrigerant at the inlet of the nozzle portion 5a. That is, the
dryness X means that refrigerant contains X kg of dry saturated
vapor and (1-X) kg of saturated liquid. Here, the COP improvement
effect means the improvement of the COP of the vapor compression
refrigerating cycle apparatus 10 with respect to the COP of the
expansion valve cycle apparatus, similar to FIG. 4. That is, the
higher the value of the COP improvement effect is, the more the COP
of the vapor compression refrigerating cycle apparatus 10 is
improved, as compared with the COP of the expansion valve cycle
apparatus.
[0075] According to FIG. 5, the COP improvement effect is low in
regions where the dryness X is small and large. The COP improvement
effect is high in the middle region. Particularly, in a region
where the dryness X is at least 0.003 and at most 0.14, the COP
improvement effect is stable and at the maximum level. That is, the
dryness X is the optimum in the range between 0.003 and 0.14.
Further, it is realized that the nozzle efficiency is sufficiently
ensured when the dryness X is in the range between 0.003 and 0.14,
similar to FIG. 3. In this case, however, the nozzle efficiency has
a peak on a side adjacent to 0.003.
[0076] Therefore, in a case where the refrigerant at the inlet of
the nozzle portion 5a has the dryness X in the range between 0.003
and 0.14, the refrigerant pressure at the inlet of the nozzle
portion 5a can be maintained to an optimum condition, similar to
FIG. 3, in accordance with the flow rate properties of the nozzle
portion 5a and the second decompressing device 4. Therefore, the
refrigerating capacity of the evaporators 7, 8 and the increase in
pressure .sub..DELTA.P by the ejector 5 are ensured in a balanced
condition. As such, the COP of the refrigerating cycle apparatus 10
is sufficiently increased, as compared with the expansion valve
cycle apparatus.
[0077] For example, the dryness X of the refrigerant at the inlet
of the nozzle portion 5a can be controlled in the range between
0.003 and 0.14 by setting the throttle degrees of the second
decompressing device 4 and the ejector 5 are to predetermined
degrees. That is, by setting the throttle degrees of the second
decompressing device 4 and the ejector 5 to the predetermined
degrees, the refrigerant at the inlet of the nozzle portion 5a can
be controlled to a predetermined condition, such as equivalent to
the condition shown in FIG. 3. Therefore, the COP of the
refrigerating cycle apparatus 10 improves.
[0078] Accordingly, in an example, the vapor compression
refrigerating cycle apparatus 10 is configured such that the
differential (P0-P) between the refrigerant pressure P0 at the
inlet of the first decompressing device 3 and the refrigerant
pressure P at the inlet of the nozzle portion 5a is equal to the
value that is obtained by multiplying the differential (P0-P2)
between the refrigerant pressure P0 and the refrigerant pressure P2
at the outlet of the nozzle portion 5a by the value that is at
least 0.1 and at most 0.6. The above pressure relationship (R1) can
be achieved by setting at least one of the throttle degrees of the
first decompressing device 3, the second decompressing device 4 and
the nozzle portion 5a to the predetermined degrees, for
example.
[0079] In this case, since the decrease in pressure at the inlet of
the nozzle portion 5a can be in the optimum condition, the
distribution ratio of the refrigerant to the second evaporator 8
and the nozzle portion 5a becomes an optimum condition. Therefore,
the performance of the evaporators 7, 8 and the efficiency of the
ejector 5, such as the nozzle efficiency and the ejector
efficiency, can be both ensured. Accordingly, the COP of the
refrigerating cycle apparatus 10 improves, as compared with the
expansion valve cycle apparatus.
[0080] Further, the above example can be employed to the vapor
compression refrigerating cycle apparatus including at least the
compressor 1, the radiator 2, the first decompressing device 3, the
flow distributor 6, the ejector 5, the second decompressing device
4, and the suction-side evaporator 8. That is, even in the vapor
compression refrigerating cycle apparatus without having the first
evaporator 7, it can be configured to have the pressure
relationship (R1). Also in this vapor compression refrigerating
cycle apparatus, the similar effects are achieved.
[0081] As another example, the vapor compression refrigerating
cycle apparatus 10 is configured such that the dryness X of the
refrigerant at the inlet of the nozzle portion 5a is in the range
between 0.003 and 0.14. The dryness X in the range between 0.003
and 0.14 is achieved by setting at least one of the throttle
degrees of the first decompressing device 3, the second
decompressing device 4 and the nozzle portion 5a to the
predetermined degree.
[0082] In such a case, since the dryness of the refrigerant at the
inlet of the nozzle portion 5a can be in the optimum condition, the
distribution ratio of the refrigerant to the second evaporator 8
and the nozzle portion 5a becomes the optimum ratio. Therefore, the
performance of the evaporators 7, 8 and the efficiency of the
ejector 5, such as the nozzle efficiency and the ejector
efficiency, can be both ensured. Accordingly, the COP of the
refrigerating cycle apparatus 10 improves, as compared with the
expansion valve cycle apparatus.
[0083] Further, the above example can be employed to the vapor
compression refrigerating cycle apparatus including at least the
compressor 1, the radiator 2, the first decompressing device 3, the
flow distributor 6, the ejector 5, the second decompressing device
4, and the suction-side evaporator 8. That is, even in the vapor
compression refrigerating cycle apparatus without having the first
evaporator 7, it can be configured such that the refrigerant has
the dryness X in the above range at the inlet of the nozzle portion
5a. Also in this vapor compression refrigerating cycle apparatus,
the similar effects are achieved.
[0084] As further another example, the vapor compression
refrigerating cycle apparatus 10 can be configured such that the
differential (P0-P) between the refrigerant pressure P0 at the
inlet of the first decompressing device 3 and the refrigerant
pressure P at the inlet of the nozzle portion 5a is equal to the
value that is obtained by multiplying the differential (P0-P2)
between the refrigerant pressure P0 and the refrigerant pressure P2
at the outlet of the nozzle portion 5a by the value that is at
least 0.1 and at most 0.6, and the dryness of the refrigerant at
the inlet of the nozzle portion 5a is in the range between 0.003
and 0.14.
[0085] In such a case, the decrease in refrigerant pressure and the
dryness of the refrigerant can be in the optimum conditions.
Therefore, the vapor compression refrigerating cycle apparatus 10
can be operated while appropriately maintaining the pressure and
enthalpy. Accordingly, the performance of the evaporators 7, 8 and
the efficiency of the ejector 5 further improves, and the COP
further improves.
[0086] In the above examples, the dryness X of the refrigerant at
the inlet of the nozzle portion 5a can be adjusted by the
distribution rate adjusting means of the flow distributor 6. In
this case, the mixing ratio of the liquid-phase refrigerant and the
gas-phase refrigerant flowing toward the nozzle portion 5a is
controlled. Therefore, the dryness X can be more precisely
adjusted.
Other Embodiments
[0087] The vapor compression refrigerating cycle apparatus 10 can
be further modified as follows.
[0088] It is not always necessary to have the discharge-side
evaporator 7. For example, as shown in FIG. 6, the discharge-side
evaporator 7 can be eliminated and an internal heat exchanger 70
that performs heat exchange between the high pressure refrigerant
discharged from the radiator 2 and the low pressure refrigerant
discharged from the ejector 5 can be added.
[0089] In this case, as shown in FIG. 7, the enthalpy of the low
pressure refrigerant discharged from the ejector 5 can be increased
from the point f1 to the point g1, and the enthalpy of the
refrigerant flowing into the suction-side evaporator 8 can be
decreased from the point b1 to a point b'1. As a result, the
capacity of the suction-side evaporator 8 increases. Also in such a
case, the refrigerating cycle apparatus can be configured to
satisfy one of or both of the pressure relationship (R1) and the
above optimum range of the dryness X. Thus, the similar effects can
be achieved.
[0090] Further, the discharge-side evaporator 7 can be eliminated,
and an accumulator as a low pressure-side gas and liquid separator
for separating the refrigerant discharged from the ejector 5 into
the gas-phase refrigerant and the liquid-phase refrigerant can be
added. Also in such a case, the refrigerating cycle apparatus can
be configured to satisfy one of or both of the pressure
relationship (R1) and the above optimum range of the dryness X.
Thus, the similar effects can be achieved.
[0091] The vapor compression refrigerating cycle apparatus 10 as
discussed hereinabove can be employed to a heat pump cycle such as
for a hot water supply apparatus or an interior air conditioner,
and mounted in a movable unit such as a vehicle or in a fixed unit
fixed at a predetermined location.
[0092] The refrigerant is not limited to R404 refrigerant. The
refrigerant can be any other types, such as chlorofluorocarbon-base
refrigerant, HC-base refrigerant, carbon dioxide refrigerant or the
like, which can be used in the supercritical cycle and the
subcritical cycle. Even when the refrigerant other than R404 is
used, the similar effects can be achieved.
[0093] The pressure relationship (R1) can be achieved by various
ways, instead by setting the throttle degree of at least one of the
first decompressing device 3, the second decompressing device 4,
and the fixed nozzle portion 5a to the predetermined degree. For
example, the ejector 5 has a flow rate variable nozzle portion in
which the throttle degree of the nozzle portion is variable in
accordance with the movement of a valve rod, in place of the fixed
nozzle portion 5a. In such a case, the pressure relationship (R1)
can be satisfied by adjusting the throttle degree of the nozzle
portion. As another example, the second decompressing device 4 can
be constructed of a flow rate control variable-type decompressing
device such as an electric control expansion valve, in place of the
capillary tube 4. In such a case, the pressure relationship (R1)
can be achieved by adjusting the throttle degree of the second
decompressing device 4. An operation of the flow rate control
variable-type decompressing device is, for example, controlled by
the control unit.
[0094] The flow distributor 6 is not limited to the block member
having the passages therein, but can be constructed of any other
types of distributors. For example, the flow distributor 6 can be
constructed of a manifold pipe having branched passages.
[0095] Additional advantages and modifications will readily occur
to those skilled in the art. The invention in its broader term is
therefore not limited to the specific details, representative
apparatus, and illustrative examples shown and described.
* * * * *