U.S. patent application number 11/921499 was filed with the patent office on 2009-05-21 for refigeration system.
Invention is credited to Masaai Takegami.
Application Number | 20090126399 11/921499 |
Document ID | / |
Family ID | 37532137 |
Filed Date | 2009-05-21 |
United States Patent
Application |
20090126399 |
Kind Code |
A1 |
Takegami; Masaai |
May 21, 2009 |
Refigeration system
Abstract
In a refrigeration system having a refrigerant circuit (20) that
is constructed in such a way that a plurality of lines of
refrigeration circuits (70, 80) having refrigeration heat
exchangers (72, 84) respectively are connected to an outdoor
circuit (30) provided with an outdoor heat exchanger (32) and a
compression mechanism (31) and conducts a vapor compression type
refrigeration cycle, at least one of the lines of refrigeration
circuits (80) having an auxiliary compressor (85) connected in
series to the refrigeration heat exchanger (84), in order to
respond to a variety of patterns of defrosting operations without
providing a defrosting mechanism other than the refrigerant circuit
(20), there is provided a hot gas introduction passage (46, 89) for
selectively introducing gas refrigerant discharged from the
compression mechanism (31) of the outdoor circuit (30) into at
least one of the plurality of refrigeration heat exchangers (72,
84) and a defrosting operation of conducting a refrigeration cycle
by using the refrigeration heat exchanger (72, 84) as a condenser
can be performed.
Inventors: |
Takegami; Masaai; (Osaka,
JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
37532137 |
Appl. No.: |
11/921499 |
Filed: |
May 30, 2006 |
PCT Filed: |
May 30, 2006 |
PCT NO: |
PCT/JP2006/310776 |
371 Date: |
December 4, 2007 |
Current U.S.
Class: |
62/510 |
Current CPC
Class: |
F25B 2400/13 20130101;
Y02B 30/70 20130101; F25B 1/10 20130101; Y02B 30/741 20130101; F25B
2400/0751 20130101; F25B 2313/02331 20130101; F25B 47/022 20130101;
F25B 2313/0231 20130101; F25B 13/00 20130101; F25B 2600/021
20130101 |
Class at
Publication: |
62/510 |
International
Class: |
F25B 1/10 20060101
F25B001/10 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 15, 2005 |
JP |
2005-175511 |
Jan 25, 2006 |
JP |
2006-016543 |
Claims
1. A refrigeration system having a refrigerant circuit (20) that is
constructed in such a way that a plurality of lines of
refrigeration circuits (70, 80) having refrigeration heat
exchangers (72, 84) respectively are connected to an outdoor
circuit (30) provided with an outdoor heat exchanger (32) and a
compression mechanism (31) and conducts a vapor compression type
refrigeration cycle, at least one of the lines of refrigeration
circuits (80) having an auxiliary compressor (85) connected in
series to the refrigeration heat exchanger (84), the refrigeration
system comprising: a hot gas introduction passage (46, 89), (100,
102) for selectively introducing gas refrigerant discharged from
the compression mechanism (31) of the outdoor circuit (30) into at
least one of the plurality of refrigeration heat exchangers (72,
84); and a defrosting path (25) capable of performing a defrosting
operation of conducting a refrigeration cycle by using that
refrigeration heat exchanger (72, 84) as a condenser.
2. The refrigeration system according to claim 1, wherein the
outdoor circuit (30) has a first refrigeration circuit (70) and a
second refrigeration circuit (80) connected thereto in parallel,
the first refrigeration circuit (70) having a first refrigeration
heat exchanger (72), the second refrigeration circuit (80) having a
second refrigeration heat exchanger (84) and the auxiliary
compressor (85).
3. The refrigeration system according to claim 1, wherein the
outdoor circuit (30) has a plurality of refrigeration circuits (80)
connected thereto in parallel, each of the plurality of
refrigeration circuits (80) having the refrigeration heat exchanger
(84) and the auxiliary compressor (85).
4. The refrigeration system according to claim 1, wherein: the
outdoor circuit (30) has an air heat exchanger circuit (60)
connected thereto, the air heat exchanger circuit (60) having an
air heat exchanger (62) for adjusting temperature of air; and a
first defrosting operation and a second defrosting operation can be
performed, the first defrosting operation using the refrigeration
heat exchangers (72, 84) as condensers and using the air heat
exchanger (62) as an evaporator, the second defrosting operation
using the refrigeration heat exchangers (72, 84) as condensers and
using the outdoor heat exchanger (32) as an evaporator.
5. The refrigeration system according to claim 1, wherein the hot
gas introduction passage (46, 89) has a high stage side hot gas
passage (46) and a low stage side hot gas passage (89), the high
stage side hot gas passage (46) being connected to a discharge line
(45) of the compression mechanism (31) of the outdoor circuit (30)
and to a base pipe (42) of a low-pressure gas line of the
respective refrigeration circuits (70, 80) and allowing a
refrigerant flow to the respective refrigeration heat exchangers
(72, 84) from the discharge line (45) of the compression mechanism
(31) at a time of a defrosting operation, the low stage side hot
gas passage (89) being connected to a discharge line (22b) and a
suction line (88) of the auxiliary compressor (85) and allowing a
refrigerant flow to the refrigeration heat exchanger (84) connected
to the auxiliary compressor (85) from the discharge line (22b) of
the auxiliary compressor (85) at the time of the defrosting
operation.
6. The refrigeration system according to claim 5, wherein: the
compression mechanism (31) of the outdoor circuit (30) includes: a
first compressor (31a), a second compressor (31b), and a third
compressor (31c), which are connected in parallel; a four-way
switching valve (37) connected to an suction side of the
compression mechanism (31); a high stage side opening/opening valve
(SV1) disposed in the high stage side hot gas passage (46); and a
low stage side opening/opening valve (SV2) disposed in the low
stage side hot gas passage (89), the first compressor (31a) having
its suction pipe (41a) connected to a first port (P1) of the
four-way switching valve (37) via a check valve (CV1) for
prohibiting a refrigerant flow to the first compressor (31a), the
second compressor (31b) having its suction pipe (41b) connected to
a second port (P2) of the four-way switching valve (37), the third
compressor (31c) having its suction pipe (41c) connected to a third
port (P3) of the four-way switching valve (37) via a check valve
(CV2) for prohibiting a refrigerant flow to the third compressor
(31c), the compression mechanism (31) having its high-pressure
introduction pipe (47) communicating with a high pressure line
connected to a fourth port (P4) of the four-way switching valve
(37); the high stage side hot gas passage (46) is connected to the
suction pipe (41a) of the first compressor (31a); and the four-way
switching valve (37) is constructed so as to be able to switch
between a first state in which the first port (P1) communicates
with the second port (P2) and in which the third port (P3)
communicates with the fourth port (P4) and a second state in which
the first port (P1) communicates with the fourth port (P4) and in
which the second port (P2) communicates with the third port
(P3).
7. The refrigeration system according to claim 5, wherein: the
compression mechanism (31) of the outdoor circuit (30) includes: a
first compressor (31a), a second compressor (31b), and a third
compressor (31c), which are connected in parallel; a four-way
switching valve (37) connected to a suction side of the compression
mechanism (31); and a low stage side opening/opening valve (SV2)
disposed in the low stage side hot gas passage (89), the first
compressor (31a) having its suction pipe 41a connected to a first
port (P1) of the four-way switching valve (37), the second
compressor (31b) having its suction pipe (41b) connected to a
second port (P2) of the four-way switching valve (37), the third
compressor (31c) having its suction pipe (41c) connected to a third
port (P3) of the four-way switching valve (37) via a check valve
(CV2) for prohibiting a refrigerant flow to the third compressor
(31c); the high stage side hot gas passage (46) is connected to a
fourth port (P4) of the four-way switching valve (37); and the
four-way switching valve (37) is constructed so as to be able to
switch between a first state in which the first port (P1)
communicates with the fourth port (P4) and in which the second port
(P2) communicates with the third port (P3) and a second state in
which the first port (P1) communicates with the second port (P2)
and in which the third port (P3) communicates with the fourth port
(P4).
8. The refrigeration system according to claim 1, wherein the hot
gas passage (46, 89) includes a first introduction passage (96) and
a second introduction passage (97), the first introduction passage
(96) introducing gas refrigerant discharged from the compression
mechanism (31) of the outdoor circuit (30) into the auxiliary
compressor (85), the second introduction passage (97) introducing
gas refrigerant discharged from the auxiliary compressor (85) into
the refrigeration heat exchanger (84).
9. The refrigeration system according to claim 8, wherein: the
second introduction passage (97) is connected to the compression
mechanism (31) of the outdoor circuit (30) and to the refrigeration
heat exchanger (84); the first introduction passage (96) is
branched from the second introduction passage (97) and is connected
to the auxiliary compressor (85) so as to introduce part of gas
refrigerant discharged from the compression mechanism (31) of the
outdoor circuit (30) into the auxiliary compressor 85; and the
second introduction passage (97) has a discharge pipe (98) of the
auxiliary compressor (85) connected to its portion closer to the
compression mechanism (31) of the outdoor circuit (30).
10. The refrigeration system according to claim 9, comprising a
liquid injection passage (99) for introducing part of liquid
refrigerant flowing out of the refrigeration heat exchanger (84)
into the auxiliary compressor (85).
11. The refrigeration system according to claim 9, wherein the
auxiliary compressor (85) is constructed of a variable displacement
compressor.
12. The refrigeration system according to claim 1, wherein the hot
gas introduction passage (100, 102) is directly connected to a
discharge line (45) of the compression mechanism (31) of the
outdoor circuit (30) and to at least one of gas side piping (110,
112) of the refrigeration heat exchangers (72, 84).
13. The refrigeration system according to claim 12, wherein the hot
gas introduction passage (100, 102) is connected to the discharge
line (45) of the compression mechanism (31) of the outdoor circuit
(30) and to the gas side piping (110, 112) of the plurality of
refrigeration heat exchangers (72, 84) and is provided with a
switching mechanism (103) capable of switching or selecting the
plurality of refrigeration heat exchangers (72, 84).
14. The refrigeration system according to claim 12, wherein the hot
gas introduction passage (100, 102) is provided with a flow control
mechanism (101).
Description
TECHNICAL FIELD
[0001] The present invention relates to a refrigeration system
having a refrigerant circuit of a vapor compression type
refrigeration cycle such that plural lines of refrigeration
circuits each having a refrigeration heat exchanger are connected
in parallel to an outdoor circuit provided with an outdoor heat
exchanger and a compression mechanism, and in particular, to a
refrigeration system such that at least one line of refrigeration
circuit has an auxiliary compressor connected in series to a
refrigeration heat exchanger.
BACKGROUND ART
[0002] A refrigeration system for conducting a refrigeration-cycle
has been known and has been widely used as a refrigeration unit of
a chiller unit or a freezer unit (or a chiller showcase or a
freezer showcase) for storing foods and the like. For example,
patent document 1 discloses a refrigeration system provided with
plural heat exchangers for refrigerating the interior of a chiller
unit or the like. In this refrigeration system, a chiller heat
exchanger for chilling the interior of a chiller showcase of a
chiller unit and a freezer heat exchanger for freezing the interior
of a freezer showcase of a freezer unit are connected in parallel
to one outdoor unit. Moreover, in this refrigeration system, an
auxiliary compressor is interposed between the freezer heat
exchanger and the outdoor unit in addition to a compression
mechanism (main compressor) of the outdoor unit. In this
refrigeration system, a single-stage refrigeration cycle, which
uses the chiller heat exchanger as an evaporator, and a two-stage
refrigeration cycle, which uses the freezer heat exchanger as an
evaporator and uses the auxiliary compressor as a low-stage
compressor, are conducted by one refrigerant circuit.
[0003] The refrigeration system of this kind presents a problem
that when moisture in air adheres to a chiller heat exchanger or a
freezer heat exchanger and freezes there, the refrigeration of air
in the refrigerator is impaired by the adhering frost. For this
reason, it is necessary to melt the frost adhering to these heat
exchangers, that is, to defrost the refrigeration heat
exchangers.
[0004] Here, in the refrigeration system disclosed in the patent
document 1, the evaporation temperature of refrigerant in the
freezer heat exchange is set comparatively low and hence the
problem of the frost developed in the freezer heat exchanger
becomes particularly serious. For this reason, the refrigeration
system conducts a refrigeration cycle for circulating refrigerant
through the auxiliary compressor, the freezer heat exchanger, an
expansion valve for the chiller heat exchanger, and the chiller
heat exchanger in this order to defrost the freezer heat
exchanger.
[0005] To this end, the refrigerant circuit of the refrigeration
system is provided with a switching mechanism capable of switching
between a first operation for a cooling operation in which the
auxiliary compressor sucks refrigerant from the freezer heat
exchanger and discharges the refrigerant to the suction side of the
compression mechanism of the outdoor unit and a second operation
for a defrosting operation in which the auxiliary compressor sucks
refrigerant from the chiller heat exchanger and discharges the
refrigerant to the freezer heat exchanger.
[0006] During the defrosting operation for defrosting the freezer
heat exchanger, the refrigerant circuit sends the refrigerant from
the freezer heat exchanger to the chiller heat exchanger while
performing the second operation. During the defrosting operation,
the refrigerant absorbs heat from air in the chiller showcase by
the chiller heat exchanger, thereby being evaporated, and is sucked
by the auxiliary compressor and is compressed by the auxiliary
compressor and is sent to the freezer heat exchanger. The
refrigerant dissipates heat in the freezer heat exchanger, thereby
being condensed, and the heat melts the frost. The condensed
refrigerant is expanded by an expansion valve before the chiller
heat exchanger and then is returned to the chiller heat exchanger
and absorbs heat from the air in the chiller showcase, thereby
being evaporated. In this manner, in the refrigeration system, the
freezer heat exchanger is defrosted by the use of heat that the
refrigerant recovers from the air in the chiller showcase when the
refrigerant flows through the auxiliary compressor, the freezer
heat exchanger, the expansion valve, and the chiller heat exchanger
in this order.
[Patent document 1] Japanese Unexamined Patent Publication No.
2004-353995
[0007] However, in the refrigeration system, when there arises a
problem that moisture in air adheres to a chiller heat exchanger
and freezes there to develop frost, whereby the refrigeration of
air in the refrigerator is impaired, it is impossible to defrost
the chiller heat exchanger by the heat of the refrigerant. Thus, to
defrost the chiller heat exchanger, the refrigeration system needs
to be provided with a defrosting mechanism such as an electric
heater in addition to the refrigerant circuit, which presents a
problem that the construction of the refrigeration system becomes
complex.
[0008] Moreover, in the above-mentioned refrigeration system, the
freezer heat exchanger is defrosted by using the chiller heat
exchanger as a heat source, so it is necessary to bring the chiller
heat exchanger and the freezer heat exchanger into a good balance
between heat absorption and heat dissipation at the time of the
defrosting operation. There is presented also a problem that this
imposes a restriction on design.
[0009] The present invention has been made in view of these
problems. The object of the present invention is to provide a
refrigeration system capable of responding to a variety of patterns
of defrosting operations without providing a defrosting mechanism
except for a refrigerant circuit and of preventing the action of
defrosting a refrigeration heat exchanger such as a chiller heat
exchanger and a freezer heat exchanger from imposing a restriction
on the design of these heat exchangers.
DISCLOSURE OF THE INVENTION
[0010] A first aspect of the invention is predicated on a
refrigeration system having a refrigerant circuit 20 that is
constructed in such a way that a plurality of lines of
refrigeration circuits 70, 80 having refrigeration heat exchangers
72, 84 respectively are connected to an outdoor circuit 30 provided
with an outdoor heat exchanger 32 and a compression mechanism 31
and conducts a vapor compression type refrigeration cycle, at least
one of the lines of refrigeration circuits 80 having an auxiliary
compressor 85 connected in series to the refrigeration heat
exchanger 84.
[0011] This refrigeration system is characterized by including: a
hot gas introduction passage 46, 89, 100, 102 for selectively
introducing gas refrigerant discharged from the compression
mechanism 31 of the outdoor circuit 30 into at least one of the
plurality of refrigeration heat exchangers 72, 84; and a defrosting
path 25 capable of performing a defrosting operation of conducting
a refrigeration cycle by using that refrigeration heat exchanger
72, 84 as a condenser.
[0012] In this first aspect of the invention, at the time of the
defrosting operation, high-temperature refrigerant discharged from
the compression mechanism 31 of the outdoor circuit 30 is
introduced into at least one of the plurality of refrigeration heat
exchangers 72, 84 via the hot gas introduction passage 46, 89, 100,
102 and the operation of a refrigeration cycle using that
refrigeration heat exchanger 72, 84 as a condenser is performed.
Thus, frost adhering to that refrigeration heat exchanger 72, 84 is
melted by heat absorbed by the heat exchanger used as an evaporator
at that time and by heat produced by compressing the refrigerant in
the compression mechanism 31. This defrosting operation can be
performed by selecting the refrigeration heat exchanger 72, 84
because the hot gas introduction passage 46, 89, 100, 102 is
provided.
[0013] A second aspect of the invention is characterized in that in
the first aspect of the invention, the outdoor circuit 30 has a
first refrigeration circuit 70 and a second refrigeration circuit
80 connected thereto in parallel, the first refrigeration circuit
70 having a first refrigeration heat exchanger 72, the second
refrigeration circuit 80 having a second refrigeration heat
exchanger 84 and the auxiliary compressor 85. The first
refrigeration circuit 70 can be made a chiller circuit for chilling
a chiller or a chiller showcase. The second refrigeration circuit
80 can be made a freezer circuit for freezing a freezer or a
freezer showcase, for example.
[0014] In this second aspect of the invention, in the refrigeration
system provided with the first refrigeration heat exchanger 72 and
the second refrigeration heat exchanger 84, by using the hot gas
introduction passage 46, 89, the defrosting operation can be
performed by a refrigeration cycle using at least one of the first
refrigeration heat exchanger 72 and the second refrigeration heat
exchanger 84 as a condenser. For example, the operation of
defrosting only one of the first refrigeration heat exchanger 72
and the second refrigeration heat exchanger 84 can be performed or
the operation of defrosting both of the first refrigeration heat
exchanger 72 and the second refrigeration heat exchanger 84 at the
same time can be performed.
[0015] A third aspect of the invention is characterized in that in
the first aspect of the invention, the outdoor circuit 30 has a
plurality of refrigeration circuits 80 connected thereto in
parallel, each of the plurality of refrigeration circuits 80 having
the refrigeration heat exchanger 84 and the auxiliary compressor
85. This refrigeration circuit can be made a freezer circuit for
freezing a freezer or a freezer showcase, for example.
[0016] In this third aspect of the invention, in the refrigeration
system provided with a plurality of refrigeration heat exchangers
84, by using the hot gas introduction passage 46, 89, the
defrosting operation can be performed by a refrigeration cycle
using at least one of the plural refrigeration heat exchangers 84
as a condenser. For example, when there are provided two
refrigeration heat exchangers 84, the operation of defrosting only
one of the refrigeration heat exchangers 84 can be performed or the
operation of defrosting both of the refrigeration heat exchangers
84 at the same time can be performed.
[0017] A fourth aspect of the invention is characterized in: that
in any one of the first aspect of the invention to the third aspect
of the invention, the outdoor circuit 30 has an air heat exchanger
circuit (e.g., air-conditioning circuit) 60 connected thereto, the
air heat exchanger circuit 60 having an air heat exchanger (e.g.,
air-conditioning heat exchanger) 62 for adjusting temperature of
air; and that a first defrosting operation and a second defrosting
operation can be performed, the first defrosting operation using
the refrigeration heat exchangers 72, 84 as condensers and using
the air heat exchanger 62 as an evaporator, the second defrosting
operation using the refrigeration heat exchangers 72, 84 as
condensers and using the outdoor heat exchanger 32 as an
evaporator.
[0018] In this fourth aspect of the invention, in the refrigeration
system provided with the plurality of refrigeration heat exchangers
72, 84 and the air heat exchanger 62, by using the hot gas
introduction passage 46, 89, a defrosting operation can be
performed by a refrigeration cycle using at least one of the plural
refrigeration heat exchangers 72, 84 as a condenser. Specifically,
the first defrosting operation using at least one of the plural
refrigeration heat exchangers 72, 84 as a condenser and using the
air heat exchanger 62 as an evaporator and the second defrosting
operation using at least one of the refrigeration heat exchangers
72, 84 as a condenser and using the outdoor heat exchanger 32 as an
evaporator can be performed.
[0019] A fifth aspect of the invention is characterized in that in
any one of the first aspect of the invention to the fourth aspect
of the invention, the hot gas introduction passage 46, 89 has a
high stage side hot gas passage 46 and a low stage hot gas passage
89, the high stage side hot gas passage 46 being connected to a
discharge line 45 of the compression mechanism 31 of the outdoor
circuit 30 and to a base pipe 42 of a low-pressure gas line of the
respective refrigeration circuits 70, 80 and allowing a refrigerant
flow to the respective refrigeration heat exchangers 72, 84 from
the discharge line 45 of the compression mechanism 31 at the time
of a defrosting operation, the low stage side hot gas passage 89
being connected to a discharge line 22b and a suction line 88 of
the auxiliary compressor 85 and allowing a refrigerant flow to the
refrigeration heat exchanger 84 connected to the auxiliary
compressor 85 from the discharge line 22b of the auxiliary
compressor 85 at the time of the defrosting operation.
[0020] In this fifth aspect of the invention, at the time of the
defrosting operation, gas refrigerant discharged from the
compression mechanism 31 of the outdoor circuit 30, first, flows
through the base pipe 42 of the low-pressure gas line of the
respective refrigeration circuits 70, 80 from high stage side hot
gas passage 46 to the respective refrigeration heat exchangers 72,
84. Then, for example, in a first refrigeration circuit (for
example, chiller circuit) 70 not provided with the auxiliary
compressor 85, the discharged gas refrigerant flows into a first
refrigeration heat exchanger (for example, chiller heat exchanger)
72 and the refrigeration heat exchanger 72 functions as a
condenser. Moreover, in a second refrigeration circuit (for
example, freezer circuit) 80 provided with the auxiliary compressor
85, the discharged gas refrigerant flows through the low stage side
hot gas passage 89 and flows into a second refrigeration heat
exchanger (for example, freezer heat exchanger) 84 and the
refrigeration heat exchanger 84 functions as a condenser.
[0021] Then, by selectively introducing the discharged gas
refrigerant into the respective refrigeration heat exchangers 72,
84, frost adhering to at least one of the refrigeration heat
exchangers 72, 84 is melted. For example, in the construction of
the second aspect of the invention, the operation of defrosting
only one of the first refrigeration heat exchanger 72 and the
second refrigeration heat exchanger 84 can be performed or the
operation of defrosting both of the first refrigeration heat
exchanger 72 and the second refrigeration heat exchanger 84 at the
same time can be performed. When two refrigeration heat exchangers
84 are provided in the construction of the third aspect of the
invention, the operation of defrosting only one of the
refrigeration heat exchangers 84 can be performed or the operation
of defrosting both of the refrigeration heat exchangers 84 at the
same time can be performed. At this time, in the refrigeration heat
exchanger 84 having the auxiliary heat exchanger 85 connected
thereto, by stopping introducing the discharged gas refrigerant
through the low stage side hot gas passage 89, there can be brought
about a state in which the defrosting operation is not
performed.
[0022] A sixth aspect of the invention is characterized in: that in
the fifth aspect of the invention, the compression mechanism 31 of
the outdoor circuit 30 includes: a first compressor 31a, a second
compressor 31b, and a third compressor 31c, which are connected in
parallel; a four-way switching valve 37 connected to an suction
side of the compression mechanism 31; a high stage side
opening/opening valve SV1 disposed in the high stage side hot gas
passage 46; and a low stage side opening/opening valve SV2 disposed
in the low stage side hot gas passage 89, the first compressor 31a
having its suction pipe 41a connected to a first port P1 of the
four-way switching valve 37 via a check valve CV1 for prohibiting a
refrigerant flow to the first compressor 31a, the second compressor
31b having its suction pipe 41b connected to a second port P2 of
the four-way switching valve 37, the third compressor 31c having
its suction pipe 41c connected to a third port P3 of the four-way
switching valve 37 via a check valve CV2 for prohibiting a
refrigerant flow to the third compressor 31c, the compression
mechanism 31 having its high-pressure introduction pipe 47
communicating with a high pressure line connected to a fourth port
P4 of the four-way switching valve 37; that the high stage side hot
gas passage 46 is connected to the suction pipe 41a of the first
compressor 31a; and that the four-way switching valve 37 is
constructed so as to be able to switch between a first state in
which the first port P1 communicates with the second port P2 and in
which the third port P3 communicates with the fourth port P4 and a
second state in which the first port P1 communicates with the
fourth port P4 and in which the second port P2 communicates with
the third port P3.
[0023] In this sixth aspect of the invention, at the time of the
defrosting operation, the four-way switching valve 37 is set to the
second state and the high stage side opening/opening valve SV1 and
the low stage side opening/opening valve SV2 are opened and two or
one of the second compressor 31b and the third compressor 31c of
the compression mechanism 31 is actuated. In this state, the gas
refrigerant discharged from the compression mechanism 31 passes
first from the high stage side hot gas passage 46 through the base
pipe 42 of the low pressure line of the respective refrigeration
circuits 70, 80 to the respective refrigeration heat exchangers 72,
84. Next, for example, in the first refrigeration circuit (for
example, chiller circuit) 70 not provided with the auxiliary
compressor 85, the discharged gas refrigerant flows into the first
refrigeration heat exchangers (for example, chiller heat exchanger)
72 and the heat exchanger 72 functions as a condenser. Moreover, in
the second refrigeration circuit (for example, freezer circuit) 80
provided with the auxiliary compressor 85, the discharged gas
refrigerant flows through the low stage side hot gas passage 89 and
flows into the second refrigeration heat exchanger (for example,
freezer heat exchanger) 84 and the heat exchanger 84 functions as a
condenser.
[0024] By selectively introducing the discharged gas refrigerant
into the respective refrigeration heat exchangers 72, 84, frost
adhering to at least one of the respective refrigeration heat
exchangers 72, 84 is melted. For example, in the construction of
the second aspect of the invention, the operation of defrosting
only one of the first refrigeration heat exchanger 72 and the
second refrigeration heat exchanger 84 can be performed or the
operation of defrosting both of the first refrigeration heat
exchanger 72 and the second refrigeration heat exchanger 84 at the
time can be performed. When two refrigeration heat exchangers 84
are provided in the construction of the third aspect of the
invention, the operation of defrosting only one of the first
refrigeration heat exchangers 84 can be performed or the operation
of defrosting both of the refrigeration heat exchangers 84 at the
time can be performed. At that time, in the refrigeration heat
exchanger 84 having the auxiliary compressor 85 connected thereto,
by closing the low stage side opening/opening valve SV2 to stop
introducing the discharged gas refrigerant through the low stage
side hot gas passage 89, there can be brought about a state in
which the defrosting operation is not performed. Moreover, the
low-pressure gas refrigerant having finished an expansion process
and an evaporation process after a condensation process in the
refrigeration heat exchangers 72, 84 passes through the four-way
switching valve 37, the suction pipe 41b, and the suction pipe 41c
and then is sucked by the second compressor 32b and the third
compressor 31c.
[0025] A seventh aspect of the invention is characterized in: that
in the fifth aspect of the invention, the compression mechanism 31
of the outdoor circuit 30 includes: a first compressor 31a, a
second compressor 31b, and a third compressor 31c, which are
connected in parallel; a four-way switching valve 37 connected to a
suction side of the compression mechanism 31; and a low stage side
opening/closing valve SV2 disposed in the low stage side hot gas
passage 89, the first compressor 31a having its suction pipe 41a
connected to a first port P1 of the four-way switching valve 37,
the second compressor 31b having its suction pipe 41b connected to
a second port P2 of the four-way switching valve 37, the third
compressor 31c having its suction pipe 41c connected to a third
port P3 of the four-way switching valve 37 via a check valve CV2
for prohibiting a refrigerant flow to the third compressor 31c;
that the high stage side hot gas passage 46 is connected to a
fourth port P4 of the four-way switching valve 37; and that the
four-way switching valve 37 is constructed so as to be able to
switch between a first state in which the first port P1
communicates with the fourth port P4 and in which the second port
P2 communicates with the third port P3 and a second state in which
the first port P1 communicates with the second port P2 and in which
the third port P3 communicates with the fourth port P4.
[0026] In this seventh aspect of the invention, at the time of the
defrosting operation, the four-way switching valve 37 is set to the
second state and the low stage side opening/closing valve SV2 is
opened and two or one of the second compressor 31b and the third
compressor 31c of the compression mechanism 31 is actuated. In this
state, the gas refrigerant discharged from the compression
mechanism 31 passes first from the high stage side hot gas passage
46 and the four-way switching valve 37 through the base pipe 42 of
the low pressure line of the respective refrigeration circuits 70,
80 to the respective refrigeration heat exchangers 72, 84. Next,
for example, in the first refrigeration circuit (for example,
chiller circuit) 70 not provided with the auxiliary compressor 85,
the discharged gas refrigerant flows into the first refrigeration
heat exchanger (for example, chiller heat exchanger) 72 and the
heat exchanger 72 functions as a condenser. Moreover, in the second
refrigeration circuit (for example, freezer circuit) 80 provided
with the auxiliary compressor 85, the discharged gas refrigerant
flows through the low stage side hot gas passage 89 and flows into
the second refrigeration heat exchanger (for example, freezer heat
exchanger) 84 and the heat exchanger 84 functions as a
condenser.
[0027] By selectively introducing the discharged gas refrigerant
into the respective refrigeration heat exchangers 72, 84, frost
adhering to at least one of the respective refrigeration heat
exchangers 72, 84 is melted. For example, in the construction of
the second aspect of the invention, the operation of defrosting
only one of the first refrigeration heat exchanger 72 and the
second refrigeration heat exchanger 84 can be performed or the
operation of defrosting both of the first refrigeration heat
exchanger 72 and the second refrigeration heat exchanger 84 at the
same time can be performed. When two refrigeration heat exchangers
84 are provided in the construction of the third aspect of the
invention, the operation of defrosting only one of the
refrigeration heat exchangers 84 can be performed or the operation
of defrosting both of the refrigeration heat exchangers 84 at the
same time can be performed. At that time, in the refrigeration heat
exchanger 84 having the auxiliary compressor 85 connected thereto,
by closing the low stage side opening/closing valve SV2 to stop
introducing the discharged gas refrigerant through the low stage
side hot gas passage 89, there can be brought about a state in
which the defrosting operation is not performed. Moreover, the
low-pressure gas refrigerant having finished an expansion process
and an evaporation process after a condensation process in the
refrigeration heat exchangers 72, 84 passes through the four-way
switching valve 37, the suction pipe 41b, and the suction pipe 41c
and then is sucked by the second compressor 32b and the third
compressor 31c.
[0028] An eighth aspect of the invention is characterized in that
in the first aspect of the invention, the hot gas passage 46, 89
includes a first introduction passage 96 and a second introduction
passage 97, the first introduction passage 96 introducing gas
refrigerant discharged from the compression mechanism 31 of the
outdoor circuit 30 into the auxiliary compressor 85, the second
introduction passage 97 introducing gas refrigerant discharged from
the auxiliary compressor 85 into the refrigeration heat exchanger
84.
[0029] In this eighth aspect of the invention, the gas refrigerant
discharged from the compression mechanism 31 of the outdoor circuit
30 is introduced into the auxiliary compressor 85 via the first
introduction passage 96 and is compressed by the auxiliary
compressor 85 and then the gas refrigerant discharged from the
auxiliary compressor 85 is introduced into the refrigeration heat
exchanger 84 via the second introduction passage 97 and is used for
defrosting the refrigeration heat exchanger 84. As described above,
at the time of defrosting operation of this eighth aspect of the
invention, the refrigerant is compressed by both of the compression
mechanism 31 of the outdoor circuit 30 and the auxiliary compressor
85, so heat given to the refrigerant at the time of the defrosting
operation can be increased.
[0030] A ninth aspect of the invention is characterized in: that in
the eighth aspect of the invention, the second introduction passage
97 is connected to the compression mechanism 31 of the outdoor
circuit 30 and to the refrigeration heat exchanger 84; that the
first introduction passage 96 is branched from the second
introduction passage 97 and is connected to the auxiliary
compressor 85 so as to introduce part of gas refrigerant discharged
from the compression mechanism 31 of the outdoor circuit 30 into
the auxiliary compressor 85; and that the second introduction
passage 97 has a discharge pipe 98 of the auxiliary compressor 85
connected to its portion closer to the compression mechanism 31 of
the outdoor circuit 30.
[0031] In this ninth aspect of the invention, part of the gas
refrigerant discharged from the compression mechanism 31 of the
outdoor circuit 30 is introduced into the auxiliary compressor 85
via the first introduction passage 96 and is further compressed by
the auxiliary compressor 85. Then, the gas refrigerant discharged
from the auxiliary compressor 85 is merged with the gas refrigerant
discharged from the compression mechanism 31 and flowing through
the second introduction passage 97 and the refrigerant after
merging is introduced into the refrigeration heat exchanger 84 and
is used for defrosting the refrigeration heat exchanger 84. As
described above, at the time of the defrosting operation of this
ninth aspect of the invention, in the nearly same manner in the
eighth aspect of the invention, the refrigerant is compressed by
both of the compression mechanism 31 of the outdoor circuit 30 and
the auxiliary compressor 85, so heat given to the refrigerant at
the time of the defrosting operation can be increased.
[0032] A tenth aspect of the invention is characterized in that the
ninth aspect of the invention, there is provided a liquid injection
passage 99 for introducing part of liquid refrigerant flowing out
of the refrigeration heat exchanger 84 into the auxiliary
compressor 85.
[0033] In this tenth aspect of the invention is performed a liquid
injecting operation for supplying the auxiliary compressor 85 with
part of the refrigerant condensed by the refrigeration heat
exchanger 84 and brought into a liquid state in the ninth aspect of
the invention. As a result, the refrigerant sucked by the auxiliary
compressor 85 is refrigerated. For this reason, it is possible to
prevent the temperature of the gas refrigerant discharged from the
auxiliary compressor 85 from being increased excessively as
compared with a case where the liquid injecting operation is not
performed.
[0034] An eleventh aspect of the invention is characterized in that
in the ninth aspect of the invention, the auxiliary compressor 85
is constructed of a variable displacement compressor.
[0035] When the defrosting operation is performed in the ninth
aspect of the invention, the temperature of the gas refrigerant
discharged from the auxiliary compressor 85 is easily increased.
However, in this eleventh aspect of the invention, the control of
lowering an operating capacity is performed to prevent the
temperature of the gas refrigerant discharged from the auxiliary
compressor 85 from being excessively increased.
[0036] A twelfth aspect of the invention is characterized in that
in the first aspect of the invention, the hot gas introduction
passage 100, 102 is directly connected to a discharge line 45 of
the compression mechanism 31 of the outdoor circuit 30 and to at
least one of gas side piping 110, 112 of the refrigeration heat
exchangers 72, 84.
[0037] In this twelfth aspect of the invention, the
high-temperature gas refrigerant discharged from the compression
mechanism 31 of the outdoor circuit 30 is introduced into at least
one of the refrigeration heat exchangers 72, 84 from the gas side.
Thus, the defrosting operation can be performed by using this
refrigeration heat exchanger 72, 84 as a condenser and by using the
other refrigeration heat exchanger as an evaporator.
[0038] A thirteenth aspect of the invention is characterized in
that in the twelfth aspect of the invention, the hot gas
introduction passage 100, 102 is connected to a discharge line 45
of the compression mechanism 31 of the outdoor circuit 30 and to
gas side piping 110, 112 of the plurality of refrigeration heat
exchangers 72, 84 and is provided with a switching mechanism 103
capable of switching or selecting the plurality of refrigeration
heat exchangers 72, 84.
[0039] In this thirteenth aspect of the invention, the defrosting
operation can be performed by switching or selecting the plurality
of refrigeration heat exchangers 72, 84.
[0040] A fourteenth aspect of the invention is characterized in
that in the twelfth aspect of the invention or the thirteenth
aspect of the invention, the hot gas introduction passage 100, 102
is provided with a flow control mechanism 101.
[0041] In this fourteenth aspect of the invention, the flow of the
high-temperature gas refrigerant flowing through the hot gas
introduction passage 100, 102 can be controlled.
EFFECTS OF THE INVENTION
[0042] According to the present invention, in the refrigeration
system in which at least one line of refrigeration circuit 80 of
the plurality of lines of refrigeration circuits 70, 80 connected
in parallel to each other has the auxiliary compressor 85 connected
in series to the refrigeration heat exchanger 84, there is provided
the hot gas introduction passage 46, 89, 100, 102 for selectively
introducing the gas refrigerant discharged from the compression
mechanism 31 of the outdoor circuit 30 into at least one of the
plurality of refrigeration heat exchangers 72, 84 and the
defrosting operation by the refrigeration cycle using the
refrigeration heat exchanger 72, 84 as the condenser can be
performed. Thus, the refrigeration heat exchangers 72, 84 can be
defrosted by the use of heat absorbed by the outdoor heat exchanger
32 and heat produced by compressing the refrigerant by the
compression mechanism 31. Further, when the refrigeration system is
provided with an air-conditioning circuit, the refrigeration heat
exchangers 72, 84 can be defrosted by the use of heat absorbed by
the air-conditioning heat exchanger 62 at the time of the cooling
operation and heat produced by compressing the refrigerant by the
compression mechanism 31.
[0043] For this reason, even if the refrigeration system is not
provided with a dedicated defrosting mechanism such as an electric
heater in addition to the refrigerant circuit 20, the refrigeration
system can perform a variety of patterns of defrosting operations.
Thus, it is possible to prevent the construction of the
refrigeration system from becoming complex. Moreover, unlike a
refrigeration system in the related art in which a freezer heat
exchanger is defrosted by using a chiller heat exchanger as a heat
source, in this refrigeration system, it is not always necessary to
bring the plural refrigeration heat exchangers 72, 84 into a good
balance between heat absorption and heat dissipation at the time of
the defrosting operation, so it is possible to enhance the degree
of flexibility in designing the refrigeration system.
[0044] According to the second aspect of the invention, in the
refrigeration circuit, the first refrigeration circuit 70 and the
second refrigeration circuit 80 are connected in parallel to the
outdoor circuit 30, the first refrigeration circuit 70 having the
first refrigeration heat exchanger 72, the second refrigeration
circuit 80 having the second refrigeration heat exchanger 84 and an
auxiliary compressor 85. Thus, the operation of defrosting only one
of the first refrigeration heat exchanger 72 and the second
refrigeration heat exchanger 84 can be performed or the operation
of defrosting both of the first refrigeration heat exchanger 72 and
the second refrigeration heat exchanger 84 at the same time can be
performed. For this reason, it is possible to perform a variety of
patterns of defrosting operations.
[0045] According to the third aspect of the invention, the
plurality of refrigeration circuits 80 each having a refrigeration
heat exchanger 84 and an auxiliary compressor 85 are connected in
parallel to the outdoor circuit 30 in the refrigeration circuit, so
for example, when there are provided two refrigeration heat
exchangers 84, the operation of defrosting only one of the
refrigeration heat exchangers 84 can be performed or the operation
of defrosting both of the refrigeration heat exchangers 84 at the
same time can be performed.
[0046] For this reason, it is possible to perform a variety of
patterns of defrosting operations. According to the fourth aspect
of the invention, the plurality of refrigeration circuits 70, 80
and the air heat exchange circuit 60 are connected to the outdoor
circuit 30, and the first defrosting operation using at least one
of the plurality of refrigeration heat exchangers 72, 84 as a
condenser and using the air heat exchanger 62 as an evaporator and
the second defrosting operation using at least one of the
refrigeration heat exchangers 72, 84 as a condenser and using the
outdoor heat exchanger 32 as an evaporator can be performed. Thus,
it is possible to perform a more variety of patterns of defrosting
operations.
[0047] According to the fifth aspect of the invention, the hot gas
introduction passage 46, 89 is constructed of the high stage side
hot gas passage 46 and the low stage hot gas passage 89, the high
stage side hot gas passage 46 allowing a refrigerant flow to the
respective refrigeration heat exchangers 72, 84 from the discharge
line 45 of the compression mechanism 31 at the time of the
defrosting operation, the low stage side hot gas passage 89
allowing a refrigerant flow to the refrigeration heat exchanger 84
connected to the auxiliary compressor 85 from the discharge line
22b of the auxiliary compressor 85 at the time of the defrosting
operation. Thus, the operation of selectively introducing the gas
refrigerant discharged from the compression mechanism 31 of the
outdoor circuit 30 into the respective refrigeration heat
exchangers 72, 84 at the time of the defrosting operation can be
performed with reliability. Moreover, by selectively introducing
the gas refrigerant discharged from the compression mechanism 31
into the respective refrigeration heat exchangers 72, 84 from the
high stage side hot gas passage 46 and the low stage hot gas
passage 89, it is possible to respond to a variety of patterns of
defrosting operations.
[0048] According to the sixth aspect of the invention, in the
refrigerant circuit 20 using three compressors 31a, 31b, 31c as the
compression mechanism 31 of the outdoor circuit 30 and using the
four-way switching valve 37 on the suction side and having the
plurality of refrigeration heat exchangers 72, 84, it is possible
to respond to a variety of patterns of defrosting operations
without making the construction of the refrigerant circuit 20
complex.
[0049] According to the seventh aspect of the invention, just as
with the sixth aspect of the invention, in the refrigerant circuit
20 using three compressors 31a, 31b, 31c as the compression
mechanism 31 of the outdoor circuit 30 and using the four-way
switching valve 37 on the suction side and having the plurality of
refrigeration heat exchangers 72, 84, it is possible to respond to
a variety of patterns of defrosting operations without making the
construction of the refrigerant circuit 20 complex.
[0050] According to the eighth aspect of the invention, heat given
to the refrigerant at the time of the defrosting operation can be
increased, so the defrosting capacity of the refrigeration heat
exchanger 84 can be increased. Thus, when the defrosting capacity
is not sufficient, by performing the control of the present
invention, the refrigeration heat exchanger 84 can be effectively
defrosted.
[0051] According to the ninth aspect of the invention, just as with
the eighth aspect of the invention, heat given to the refrigerant
at the time of the defrosting operation can be increased, so the
defrosting capacity of the refrigeration heat exchanger 84 can be
increased. Thus, when the defrosting capacity is not sufficient, by
performing the control of the present invention, the refrigeration
heat exchanger 84 can be effectively defrosted.
[0052] According to the tenth aspect of the invention, by
performing the liquid injecting operation at the time of defrosting
operation in the ninth aspect of the invention, it is possible to
avoid the temperature of the gas refrigerant discharged from the
auxiliary compressor 85 from being abnormally increased and hence
to protect the auxiliary compressor 85 with reliability.
[0053] According to the eleventh aspect of the invention, by
decreasing the operating capacity of the auxiliary compressor 85 at
the time of the defrosting operation in the ninth aspect of the
invention, it is possible to avoid the temperature of the gas
refrigerant discharged from the auxiliary compressor 85 from being
abnormally increased and hence to protect the auxiliary compressor
85 with reliability.
[0054] According to the twelfth aspect of the invention, the hot
gas introduction passage 100, 102 is directly connected to the
discharge line 45 of the compression mechanism 31 of the outdoor
circuit 30 and to at least one of the gas side piping 110, 112 of
the refrigeration heat exchangers 72, 84. Thus, the
high-temperature gas refrigerant discharged from the compression
mechanism 31 of the outdoor circuit 30 is introduced into at least
one of the refrigeration heat exchangers 72, 84 from the gas side.
Thus, the defrosting operation can be performed by using this
refrigeration heat exchanger 72, 84 as a condenser and by using the
other refrigeration heat exchanger as an evaporator.
[0055] According to the thirteenth aspect of the invention, the hot
gas introduction passage 100, 102 is connected to the discharge
line 45 of the compression mechanism 31 of the outdoor circuit 30
and to the gas side piping 110, 112 of the plurality of
refrigeration heat exchangers 72, 84 and is provided with the
switching mechanism 103 capable of switching or selecting the
plurality of refrigeration heat exchangers 72, 84. Thus, the
defrosting operation can be performed by switching or selecting the
plurality of refrigeration heat exchangers 72, 84.
[0056] According to the fourteenth aspect of the invention, the hot
gas introduction passage 100, 102 is provided with the flow control
mechanism 101, so the flow of the high-temperature gas refrigerant
flowing through the hot gas introduction passage 100, 102 can be
controlled. Here, when the flow of the gas refrigerant flowing
through the hot gas introduction passage 100, 102 is large, frost
adhering to the refrigeration heat exchangers 72, 84 is melted at a
stretch and hence the block of the frost around the refrigeration
heat exchangers 72, 84 might be dropped. However, by decreasing the
flow of the refrigerant, the frost can be gradually melted and
hence it is possible to prevent the block of the frost from being
dropped.
BRIEF DESCRIPTION OF THE DRAWINGS
[0057] FIG. 1 is a refrigerant circuit diagram of a refrigeration
system according to an embodiment 1.
[0058] FIG. 2 is a refrigerant circuit diagram showing an operation
at the time of a cooling operation in the embodiment 1.
[0059] FIG. 3 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of the cooling operation in
the embodiment 1.
[0060] FIG. 4 is a refrigerant circuit diagram showing another
example of the defrosting operation at the time of the cooling
operation in the embodiment 1.
[0061] FIG. 5 is a refrigerant circuit diagram showing an operation
at the time of a heating operation in the embodiment 1.
[0062] FIG. 6 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of the heating operation in
the embodiment 1.
[0063] FIG. 7 is a refrigerant circuit diagram showing another
example of the defrosting operation at the time of the heating
operation in the embodiment 1.
[0064] FIG. 8 is a refrigerant circuit diagram of a refrigeration
system according to an embodiment 2.
[0065] FIG. 9 is a refrigerant circuit diagram showing an operation
at the time of a cooling operation in the embodiment 2.
[0066] FIG. 10 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of the cooling operation in
the embodiment 2.
[0067] FIG. 11 is a refrigerant circuit diagram showing another
example of the defrosting operation at the time of the cooling
operation in the embodiment 2.
[0068] FIG. 12 is a refrigerant circuit diagram showing an
operation at the time of a heating operation in the embodiment
2.
[0069] FIG. 13 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of the heating operation in
the embodiment 2.
[0070] FIG. 14 is a refrigerant circuit diagram showing another
example of the defrosting operation at the time of the heating
operation in the embodiment 2.
[0071] FIG. 15 is a refrigerant circuit diagram of a refrigeration
system according to an embodiment 3.
[0072] FIG. 16 is a refrigerant circuit diagram showing an
operation at the time of a cooling operation in the embodiment
3.
[0073] FIG. 17 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of the cooling operation in
the embodiment 3.
[0074] FIG. 18 is a refrigerant circuit diagram showing another
example of the defrosting operation at the time of the cooling
operation in the embodiment 3.
[0075] FIG. 19 is a refrigerant circuit diagram showing an
operation at the time of a heating operation in the embodiment
3.
[0076] FIG. 20 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of the heating operation in
the embodiment 3.
[0077] FIG. 21 is a refrigerant circuit diagram showing another
example of the defrosting operation at the time of the heating
operation in the embodiment 3.
[0078] FIG. 22 is a refrigerant circuit diagram showing an example
of a defrosting operation at the time of a cooling operation in an
embodiment 4.
[0079] FIG. 23 is a refrigerant circuit diagram of a refrigeration
system according to an embodiment 5.
REFERENCE NUMERAL
[0080] 10 refrigeration system [0081] 20 refrigerant circuit [0082]
22b discharge line (freezer side branch gas pipe) [0083] 25
defrosting path [0084] 30 outdoor circuit [0085] 31 compression
mechanism [0086] 31a DC inverter compressor (first compressor)
[0087] 31b first non-inverter compressor (second compressor) [0088]
31c second non-inverter compressor (third compressor) [0089] 32
outdoor heat exchanger [0090] 37 third four-way switching valve
[0091] 41a first suction pipe (suction pipe) [0092] 41b second
suction pipe (suction pipe) [0093] 41c third suction pipe (suction
pipe) [0094] 41c first low-pressure gas pipe (base pipe of a
low-pressure gas line) [0095] 45 discharge line (high-pressure gas
pipe) [0096] 46 high stage side hot gas passage (hot gas
introduction passage) [0097] 47 high-pressure introduction pipe
[0098] 48 air-conditioning circuit [0099] 60 air-conditioning heat
exchanger [0100] 62 chiller circuit (refrigeration circuit) [0101]
72 chiller heat exchanger (refrigeration heat exchanger) [0102] 80
freezer circuit (refrigeration circuit) [0103] 84 freezer heat
exchanger (refrigeration heat exchanger) [0104] 85 booster
compressor (auxiliary compressor) [0105] 88 suction line [0106] 89
low stage side hot gas passage (hot gas introduction passage)
[0107] 96 first introduction passage [0108] 97 second introduction
passage [0109] 98 discharge pipe [0110] 99 liquid injection passage
[0111] 100 hot gas introduction passage [0112] 101 flow control
mechanism [0113] 102 branch pipe (hot gas introduction passage)
[0114] 110 gas side piping [0115] 112 gas side piping [0116] CV1
check valve [0117] CV2 check valve [0118] P1 first port [0119] P2
second port [0120] P3 third port [0121] P4 fourth port [0122] SV1
high stage side opening/closing valve [0123] SV2 low stage side
opening/closing valve
BEST MODE FOR CARRYING OUT THE INVENTION
[0124] The preferred embodiments of the present invention will be
described below in detail with reference to the drawings.
Embodiment 1 of the Invention
[0125] An embodiment 1 of the present invention will be described.
A refrigeration system 10 of this embodiment is installed in a
convenience store or the like and air-conditions the store and
refrigerates the interior of a showcase.
[0126] As shown in FIG. 1, the refrigeration system 10 of this
embodiment has an outdoor unit 11, an air-conditioning unit 12, a
chiller showcase 13 as a chiller unit, a freezer showcase 14 as a
freezer unit. The outdoor unit 11 is installed outdoors. On the
other hand, all of the air-conditioning unit 12, the chiller
showcase 13, and the freezer showcase 14 are installed in the
convenience store or the like.
[0127] The outdoor unit 11 is provided with an outdoor circuit 30.
The air-conditioning unit 11 is provided with an air-conditioning
circuit (air heat exchanger circuit) 60. The chiller showcase 13 is
provided with a chiller circuit (first refrigeration circuit) 70.
The freezer showcase 14 is provided with a freezer circuit (second
refrigeration circuit) 80. In this refrigeration system 10, these
circuits 30, 60, 70, and 80 are connected by piping to construct a
refrigerant circuit 20. The refrigerant circuit 20 includes a
chiller/freezer circuit and an air-conditioning circuit.
[0128] On the chiller/freezer side of the refrigerant circuit 20,
the chiller circuit 70 and the freezer circuit 80 both of which are
the refrigeration circuits are connected in parallel to the outdoor
circuit 30. Specifically, the chiller circuit 70 and the freezer
circuit 80 are connected to the outdoor circuit 30 via first liquid
side connection piping 21 and first gas side connection piping 22.
The first liquid side connection piping 21 has its one end
connected to the outdoor circuit 20. The first liquid side
connection piping 21 has its other end branched into two parts and
has one (chiller side branch liquid pipe 21a) of the branched parts
connected to the liquid side end of the chiller circuit 70 and has
the other (freezer side branch liquid pipe 21b) of the branched
parts connected to the liquid side end of the freezer circuit 80.
The first gas side connection piping 22 has its one end connected
to the outdoor circuit 30. The first gas side connection piping 22
has its other end branched into two parts and has one (chiller side
branch gas pipe 22a) of the branched parts connected to the gas
side end of the chiller circuit 70 and has the other (freezer side
branch gas pipe 22b) of the branched parts connected to the gas
side end of the freezer circuit 80.
[0129] Moreover, on the air-conditioning side of the refrigerant
circuit 20, the air-conditioning circuit 60 is connected to the
outdoor circuit 30 via second liquid side connection piping 23
branched from the first liquid side connection piping 21 and second
gas side connection piping 24. The second liquid side connection
piping 23 has its one end connected to the outdoor circuit 30 via
the first liquid side connection piping 21 and has its other end
connected to the liquid side end of the air-conditioning circuit
60. The second gas side connection piping 24 has its one end
connected to the outdoor circuit 30 and has its other end connected
to the gas side end of the air-conditioning circuit 60.
[0130] (Outdoor Unit)
[0131] As described above, the outdoor unit 11 is provided with the
outdoor circuit 30. The outdoor circuit 30 is provided with a
compression mechanism 31, an outdoor heat exchanger 32, a receiver
33, and an outdoor expansion valve 34. Moreover, the outdoor
circuit 30 is provided with a first four-way switching valve 35, a
second four-way switching valve 36, a third four-way switching
valve 37, a liquid side stop valve 38, a first gas side stop valve
39a, and a second gas side stop valve 39b. In this outdoor circuit
30, the liquid side stop valve 38 has the first liquid side
connection piping 21 connected thereto and the first gas side stop
valve 39a has the first gas side connection piping 22 connected
thereto and the second gas side stop valve 39b has the second gas
side connection piping 24 connected thereto.
[0132] The compression mechanism 31 is constructed of a DC inverter
compressor 31a of a first compressor, a first non-inverter
compressor 31b of a second compressor, and a second non-inverter
compressor 31c of a third compressor, which are connected in
parallel to each other. The respective compressors 31a, 31b, and
31c are scroll compressors of a hermetic high-pressure dome type,
respectively. The DC inverter compressor 31a is supplied with
electric power via an inverter. By changing the output frequency of
the inverter of the DC inverter compressor 31a to change the
rotation speed of its electric motor, the operation capacity of the
DC inverter compressor 31a can be adjusted. On the other hand, the
first non-inverter compressor 31b and the second non-inverter
compressor 31c have their electric motors driven always at their
specified rotation speeds and hence have their operation capacities
kept constant.
[0133] The DC inverter compressor 31a has one end of a first
suction pipe 41a connected to its suction side. The first
non-inverter compressor 31b has one end of a second suction pipe
41b connected to its suction side. The second non-inverter
compressor 31c has one end of a third suction pipe 41c connected to
its suction side.
[0134] The other end of the first suction pipe 41a is connected to
a first low-pressure gas pipe 42 of the base pipe of a
chiller/freezer line low-pressure gas line and a first
communication pipe 43a and the first low-pressure gas pipe 42 is
connected to the first gas side stop valve 39a. The first suction
pipe 41a is connected to a first port P1 of the third four-way
switching valve 37 via the first communication pipe 43a. The first
communication pipe 43a is provided with a check valve CV1 for
prohibiting a refrigerant flow to the DC inverter compressor 31a.
The other end of the second suction pipe 41a is connected to a
second port P2 of the third four-way switching valve 37. The other
end of the third suction pipe 41c is connected to a second
low-pressure gas pipe 44 and a second communication pipe 43b and
the second low-pressure gas pipe 44 is connected to a second
four-way switching valve 36. The third suction pipe 41c is
connected to a third port P3 of the third four-way switching valve
37 via the second communication pipe 43b. The second communication
pipe 43b is provided with a check valve CV2 for prohibiting a
refrigerant flow to the second non-inverter compressor 31c.
[0135] The compression mechanism 31 has a high-pressure gas pipe
(discharge line) 45 connected to its discharge side. The
high-pressure gas pipe 45 has one end of a high stage side hot gas
passage 46 connected thereto and the other end of the high stage
side hot gas passage 46 is connected to the first suction pipe 41a.
The high stage side hot gas passage 46 has a first solenoid valve
SV1 as a high stage side opening/opening valve. The high stage side
hot gas passage 46 is a passage which is connected to the discharge
line 45 of the compression mechanism 31 of the outdoor circuit 30
and to the first low-pressure gas pipe 42 of the base pipe of the
low-pressure gas line of the respective refrigeration circuits 70,
80 and allows a refrigerant flow to the respective refrigeration
heat exchangers 72, 84 from the discharge line 45 of the
compression mechanism 31 at the time of the defrosting
operation.
[0136] The high stage side hot gas passage 46 has one end of a
high-pressure introduction pipe 47 connected between the discharge
side of the compression mechanism 31 and the first solenoid valve
SV1. The high-pressure introduction pipe 47 communicates with the
high pressure line of the compression mechanism 31 via the high
stage side hot gas passage 46 and has its other end connected to a
fourth port P4 of the third four-way switching valve 37.
[0137] This third four-way switching valve 37 can switch between a
first state (state shown by a solid line in FIG. 1) in which the
first port P1 and the second port P2 communicate with each other
and in which the third port P3 and the fourth port P4 communicate
with each other and a second state (state shown by a broken line in
FIG. 1) in which the first port P1 and the fourth port P4
communicate with each other and in which the second port P2 and the
third port P3 communicate with each other.
[0138] The DC inverter compressor 31a has a first discharge pipe
48a connected to its discharge side and the first non-inverter
compressor 31b has a second discharge pipe 48b connected to its
discharge side and the second non-inverter compressor 31c has a
third discharge pipe 48c connected to its discharge side. The first
discharge pipe 48a is provided with a check valve CV3 for
prohibiting a refrigerant flow to the DC inverter compressor 31a
and the second discharge pipe 48b is provided with a check valve
CV4 for prohibiting a refrigerant flow to the first non-inverter
compressor 31b and the third discharge pipe 48c is provided with a
check valve CV5 for prohibiting a refrigerant flow to the second
non-inverter compressor 31c. The first discharge pipe 48a, the
second discharge pipe 48b, and the third discharge pipe 48c are
merged with each other and connected to the high-pressure gas pipe
45. The third discharge pipe 48c has a discharge connection pipe 49
connected between the point where the third discharge pipe 48c is
connected to the high pressure pipe 45 and the check valve CV5.
[0139] In the first four-way switching valve 35, the first port P1
is connected to the high-pressure gas pipe 45 and the second port
P2 is connected to the outdoor heat exchanger 32 via a first gas
pipe 50 and the third port P3 is connected to the second four-way
switching valve 36 via a gas connection pipe 52 and the fourth port
P4 is connected to the second gas side stop valve 39b via a second
gas pipe 51. The first four-way switching valve 35 can switch
between a first state (state shown by a solid line in FIG. 1) in
which the first port P1 and the second port P2 communicate with
each other and in which the third port P3 and the fourth port P4
communicate with each other and a second state (state shown by a
broken line in FIG. 1) in which the first port P1 and the fourth
port P4 communicate with each other and in which the second port P2
and the third port P3 communicate with each other.
[0140] In the second four-way switching valve 36, the first port P1
is connected to the discharge connection pipe 49 and the third port
P3 is connected to the second low-pressure gas pipe 44 and the
fourth port P4 is connected to the gas connection pipe 52.
Moreover, the second four-way switching valve 36 has its second
port P2 closed. This second four-way switching valve 36 can switch
between a first state (state shown by a solid line in FIG. 1) in
which the first port P1 and the second port P2 communicate with
each other and in which the third port P3 and the fourth port P4
communicate with each other and a second state (state shown by a
broken line in FIG. 1) in which the first port P1 and the fourth
port P4 communicate with each other and in which the second port P2
and the third port P3 communicate with each other.
[0141] The outdoor heat exchanger 32 is a fin-and-tube heat
exchanger of a cross fin type and constructs a heat source side
heat exchanger. An outdoor fan 32a is disposed near the outdoor
heat exchanger 32. Outdoor air is sent to the outdoor heat
exchanger 32 by the outdoor fan 32a and heat is exchanged between
the refrigerant and the outdoor air in the outdoor heat exchanger
32. The outdoor heat exchanger 32, as described above, has its one
end connected to the first four-way switching valve 35. On the
other hand, the outdoor heat exchanger 32 has its other end
connected to the top of a receiver 33 via a first liquid pipe 53.
The first liquid pipe 53 is provided with a check valve CV6 that
allows a refrigerant flow to the receiver 33 from the outdoor heat
exchanger 32 and prohibits a back flow.
[0142] The receiver 33 has one end of a second liquid pipe 54
connected to its bottom. The second liquid pipe 54 has its other
end connected to a liquid side stop valve 38. The second liquid
pipe 54 is provided with a check valve CV7 that allows a
refrigerant flow to a liquid side stop valve 38 from the receiver
33 and prohibits a back flow.
[0143] In the second liquid pipe 54, one end of a third liquid pipe
55 is connected between the check valve CV7 and the liquid side
stop valve 38. The other end of the third liquid pipe 55 is
connected to the top of the receiver 33. The third liquid pipe 55
is provided with a check valve CV8 that allows a refrigerant flow
to the receiver 33 from the liquid side stop valve 38 and prohibits
a back flow.
[0144] One end of a fourth liquid pipe 56 is connected between the
receiver 33 and the check valve CV7 in the second liquid pipe 54.
The other end of the fourth liquid pipe 56 is connected between the
outdoor heat exchanger 32 and check valve CV6 in the first liquid
pipe 53. Moreover, the fourth liquid pipe 56 is provided with an
outdoor expansion valve 34.
[0145] The outdoor circuit 30 is provided with also various sensors
and pressure switches. For example, the high-pressure gas pipe 45
is provided with a discharge temperature sensor 57 and a discharge
pressure sensor (not shown). Each of the first discharge pipe 48a
and the third discharge pipe 48c is provided with a high-pressure
pressure sensor 58. Moreover, each of the suction pipes 41a, 41b,
and 41c is provided with a suction temperature sensor and a suction
pressure sensor although they are not shown. Furthermore, an
outdoor air temperature sensor 59 is disposed near the outdoor fan
32a.
[0146] (Air-Conditioning Unit)
[0147] As described above, the air-conditioning unit 12 has an
air-conditioning circuit (air heat exchange circuit) 60. In the
air-conditioning circuit 60, an air-conditioning expansion valve 61
and an air heat exchanger 62 are disposed in this order from a
liquid side end to a gas side end. The air heat exchanger 62 is
constructed of a fin-and-tube heat exchanger of a cross fin type.
In this air heat exchanger 62, heat is exchanged between the
refrigerant and the indoor air. On the other hand, the
air-conditioning expansion valve 61 is constructed of an electronic
expansion valve.
[0148] The air-conditioning unit 12 is provided with a heat
exchanger temperature sensor 63 and a refrigerant temperature
sensor 64. The heat exchanger temperature sensor 63 is disposed in
a heat exchanger tube of the air heat exchanger 62. The refrigerant
temperature sensor 64 is disposed near a gas side end in the
air-conditioning circuit 60. Moreover, the air-conditioning unit 12
is provided with an indoor air temperature sensor 65 and an
air-conditioning fan 66. Indoor air in the store is sent to the air
heat exchanger 62 by the air-conditioning fan 66.
[0149] (Chiller Showcase)
[0150] As described above, the chiller showcase 13 has a chiller
circuit 70. In the chiller circuit 70, a chiller expansion valve 71
and a chiller heat exchanger (first refrigeration heat exchanger)
72 are disposed in this order from its liquid side end to a gas
side end. The chiller heat exchanger 72 is constructed of a
fin-and-tube heat exchanger of a cross fin type. In this chiller
heat exchanger 72, heat is exchanged between the refrigerant and
the air in the chiller showcase 13. On the other hand, the chiller
expansion valve 71 is constructed of an electronic expansion
valve.
[0151] The chiller showcase 13 is provided with a heat exchanger
temperature sensor 73 and refrigerant temperature sensors 74, 75.
The heat exchanger temperature sensor 73 is disposed in a heat
exchanger tube of the chiller heat exchanger 72. A gas refrigerant
temperature sensor 74 is disposed near a gas side end in the
chiller circuit 70 and a liquid refrigerant temperature sensor 75
is disposed near a liquid side end in the chiller circuit 70.
Moreover, the chiller showcase 13 is provided with a chiller
temperature sensor 76 and a chiller fan 77. Air in the chiller
showcase 13 is sent to the chiller heat exchanger 72 by the chiller
fan 77.
[0152] (Freezer Showcase)
[0153] As described above, the freezer showcase 14 has a freezer
circuit 80. In the freezer circuit 80, a refrigerant heat exchanger
81, a drain pan heater 82, a freezer expansion valve 83, a freezer
heat exchanger (second refrigeration heat exchanger) 84, and a DC
inverter compressor used as a booster compressor (auxiliary
compressor) 85 are disposed in this order from its liquid side end
to a gas side end. The freezer heat exchanger 84 is constructed of
a fin-and-tube heat exchanger of a cross fin type. In this freezer
heat exchanger 84, heat is exchanged between the refrigerant and
the air in the freezer showcase 14. On the other hand, the freezer
expansion valve 83 is constructed of an electronic expansion valve.
The freezer expansion valve 83 is an expansion valve that is
disposed in a freezer circuit 80 and can change the degree of
opening.
[0154] The refrigerant heat exchanger 81 is a heat exchanger in
which the refrigerants exchange heat between them and is
constructed of a plate heat exchanger, for example. This
refrigerant heat exchanger 81 has a high pressure side passage 81a
connected to a freezer side branch liquid pipe 21b and a low
pressure side passage 81b connected to a branch pipe 86 branched
from the downstream side of the high pressure side passage 81a in
the freezer side branch liquid pipe 21b. The branch pipe 86 has an
electronic expansion valve disposed upstream of the low pressure
side passage 81b and has the downstream side of the low pressure
side passage 81b connected to an intermediate-pressure position of
the booster compressor 85. An economizer is constructed of the
refrigerant heat exchanger 81 and the electronic expansion valve
87.
[0155] A check valve CV9 that allows refrigerant to be discharged
from the booster compressor 85 and prohibits the back flow of the
refrigerant is disposed in a freezer side branch gas pipe 22b of
the discharge line of the booster compressor 85. A low stage side
hot gas passage 89 is connected between a downstream position of
the check valve CV9 in the freezer side branch gas pipe 22b and a
suction pipe 88 of the suction line of the booster compressor 85.
The low stage side hot gas passage 89 is a passage, which is
connected to the freezer side branch gas pipe 22b and the suction
pipe 88 and allows a refrigerant flow to the freezer heat exchanger
84 from the freezer side branch gas pipe 22b at the time of the
defrosting operation, and is provided with a second solenoid valve
SV2 of a low stage side opening/opening valve.
[0156] The freezer showcase 14 is provided with a heat exchanger
temperature sensor 90 and refrigerant temperature sensors 91, 92.
The heat exchanger temperature sensor 90 is fixed to a heat
exchanger tube of the freezer heat exchanger 84. A gas refrigerant
temperature sensor 91 is disposed near a gas side end in the
freezer circuit 80. A liquid refrigerant temperature sensor 92 is
disposed near a liquid side end in the freezer circuit 80. A drain
pan heater temperature sensor 93 is disposed near the drain pan
heater 82. Moreover, the freezer showcase 14 is provided with a
freezer temperature sensor 94 and a freezer fan 95. Air in the
freezer showcase 14 is sent to the freezer heat exchanger 84 by the
freezer fan 95.
[0157] (Entire Construction of Refrigerant Circuit)
[0158] As described above, the refrigerant circuit 20 of this
embodiment has the chilling/freezer line side circuit and the
air-conditioning line side circuit. In the chilling/freezer line
side circuit, the plural refrigeration circuits (chiller circuit 70
and freezer circuit 80), which have refrigeration heat exchangers
72, 84 respectively, are connected in parallel to the outdoor
circuit 30 provided with the outdoor heat exchanger 32 and the
compression mechanism 31. In at least the freezer circuit 30 of one
line refrigeration circuit, the booster compressor 85 is connected
in series to the freezer heat exchanger 84.
[0159] The refrigerant circuit 20 of this embodiment has a high
stage side hot gas passage 46 and a low stage side hot gas passage
89 as hot gas introduction passages 46, 89 for selectively
introducing the gas refrigerant discharged from the compression
mechanism 31 of the outdoor circuit 30 into at least one of the
plural refrigeration heat exchangers 72, 84 and is constructed so
as to perform the defrosting operation of conducting the
refrigeration cycle by using the refrigeration heat exchangers 72,
84 as condensers.
[0160] Moreover, the refrigerant circuit 20 includes the
air-conditioning circuit 60 that has the air-conditioning heat
exchanger 62 and air-conditions the room. As will be described
later, the refrigerant circuit 20 is constructed so as to perform
the defrosting operation (first defrosting operation) at the time
of a cooling operation in which the refrigeration heat exchangers
72, 84 are used as condensers and in which the air-conditioning
heat exchanger 62 is used an evaporator and the defrosting
operation (second defrosting operation) at the time of a heating
operation in which the refrigeration heat exchangers 72, 84 are
used as condensers and in which the outdoor heat exchanger 32 is
used an evaporator.
--Operation--
[0161] Of operations performed by the refrigeration system, main
operations will be described below.
[0162] (Cooling Operation)
[0163] A cooling operation is the operation of refrigerating air in
the chiller showcase 13 and the freezer showcase 14 and
refrigerating air in the store by the air-conditioning unit 12 to
cool the interior of the store.
[0164] As shown in FIG. 2, in the refrigerant circuit 20, the first
four-way switching valve 35, the second four-way switching valve
36, and the third four-way switching valve 37 are set to the first
state. Moreover, the outdoor expansion valve 34 is totally closed,
and the air-conditioning expansion valve 61, the chiller expansion
valve 71, and the freezer expansion valve have their degrees of
opening suitably adjusted, and the first solenoid valve SV1 of the
high stage side hot gas passage 46 and the second solenoid valve
SV2 of the low stage side hot gas passage 89 are closed. In this
state, the DC inverter compressor 31a, the first non-inverter
compressor 31b, the second non-inverter compressor 31c, and the
booster compressor 85 are operated.
[0165] The refrigerants discharged from the DC inverter compressor
31a, the first non-inverter compressor 31b, and the second
non-inverter compressor 31c pass through the respective discharge
pipes 48a, 48b, and 48c and merge with each other in the
high-pressure gas pipe 45. Then, the refrigerant after merging
passes through the first four-way switching valve 35 and is sent to
the outdoor heat exchanger 32. In the outdoor heat exchanger 32,
the refrigerant dissipates heat to the outdoor air, thereby being
condensed.
[0166] The refrigerant condensed in the outdoor heat exchanger 32
passes through the receiver 33 and flows to the first liquid side
connection piping 21 and is distributed to the chiller side branch
liquid pipe 21a, the freezer side branch liquid pipe 21b, and the
second liquid side connection piping 23.
[0167] The refrigerant flowing into the chiller circuit 70 from the
chiller side branch liquid pipe 21a has its pressure reduced when
the refrigerant passes the chiller expansion valve 71 and then is
introduced into the chiller heat exchanger 72. In the chiller heat
exchanger 72, the refrigerant absorbs heat from the air in the
chiller showcase 13, thereby being evaporated. At this time, in the
chiller heat exchanger 72, the evaporation temperature of the
refrigerant is set to about -5.degree. C., for example. The
refrigerant evaporated in the chiller heat exchanger 72 flows
through the chiller side branch gas pipe 22a and flows into the
first gas side connection piping 22. In the chiller showcase 13,
the air refrigerated by the chiller heat exchanger 72 is supplied
into the chiller showcase 13, whereby the temperature in the
chiller showcase 13 is kept at about 5.degree. C., for example.
[0168] The refrigerant flowing from the freezer side branch liquid
pipe 21b into the freezer circuit 80 passes through the refrigerant
heat exchanger 81 and the drain pan heater 82. Then, when the
refrigerant passes through the freezer expansion valve 83, the
refrigerant has its pressure reduced and then is introduced into
the freezer heat exchanger 84. In the freezer heat exchanger 84,
the refrigerant absorbs heat from the air in the freezer showcase
14, thereby being evaporated. At this time, in the freezer heat
exchanger 84, the evaporation temperature of the refrigerant is set
at about -30.degree. C., for example. In the freezer showcase 14,
the air in the freezer showcase 14 refrigerated by the freezer heat
exchanger 84 is supplied into the freezer showcase 14, whereby the
temperature in the freezer showcase 14 is kept at about -20.degree.
C., for example.
[0169] The refrigerant evaporated in the freezer heat exchanger 84
passes through the suction pipe 88 and is sucked into the booster
compressor 85. The refrigerant compressed by the booster compressor
85 passes through the discharge pipe 98 and the freezer side branch
gas pipe 22b and flows into the first gas side connection piping
22.
[0170] In the first gas side connection piping 22, the refrigerant
sent from the chiller circuit 70 and the refrigerant sent from the
freezer circuit 80 merge with each other. These refrigerants pass
through the first gas side connection piping 22 and the first
low-pressure suction pipe 42 and flow into the first suction pipe
41a and the second suction pipe 41b and then are sucked by the DC
inverter compressor 31a and the first non-inverter compressor 31b.
The DC inverter compressor 31a and the first non-inverter
compressor 31b compress the sucked refrigerants and discharge the
refrigerants to the first discharge pipe 48a and the second
discharge pipe 48b.
[0171] On the other hand, the refrigerant flowing into the second
liquid side connection piping 23 is supplied to the
air-conditioning circuit 60. The refrigerant flowing into the
air-conditioning circuit 60 has its pressure reduced when the
refrigerant passes through the air-conditioning expansion valve 61.
Then, the refrigerant is introduced into the air-conditioning heat
exchanger 62. In the air-conditioning heat exchanger 62, the
refrigerant absorbs heat from the indoor air, thereby being
evaporated. In the air-conditioning unit 12, the indoor air cooled
by the air-conditioning heat exchanger 62 is supplied into the
store. The refrigerant evaporated in the air-conditioning heat
exchanger 62 passes through the second gas side connection piping
24 and flows into the outdoor circuit 30 and passes through the
second gas pipe 51, the first four-way switching valve 35, and the
second four-way switching valve 36 in sequence and then passes
through the second low-pressure gas pipe 44 and the third suction
pipe 41c and then is sucked by the second non-inverter compressor
31c. The second non-inverter compressor 31c compresses the sucked
refrigerant and discharges the refrigerant to the third discharge
pipe 48c.
[0172] At the time of the cooling operation shown in FIG. 2, by
setting the third four-way switching valve 37 to the first state,
two compressors 31a, 31b are used for the chilling/freezer line
side circuit and one compressor 31c is used for the
air-conditioning line side circuit. However, by switching the third
four-way switching valve 37 to the second state, it is also
possible to use one compressor 31a for the chilling/freezer line
side circuit and to use two compressors 31b, 31c for the
air-conditioning line side circuit. Moreover, by stopping one of
three compressors 31a, 31b, and 31c in a state in which the third
four-way switching valve 37 is set to either the first state or the
second state, it is also possible to use one compressor for each of
the chilling/freezer line side circuit and the air-conditioning
line side circuit.
[0173] (Defrosting Operation at the Time of the Cooling
Operation)
[0174] As for the defrosting operation at the time of the cooling
operation, the defrosting operation shown in FIG. 3 in which the
chiller heat exchanger 72 and the freezer heat exchanger 84 are
defrosted at the same time and the defrosting operation shown in
FIG. 4 in which the chiller heat exchanger 72 is defrosted while
the freezer heat exchanger 84 performs a freezing operation can be
performed. Here, a refrigerant flow at the time of the defrosting
operation (defrosting path) is designated by a reference symbol 25.
First, the defrosting operation shown in FIG. 3 will be
described.
[0175] As shown in FIG. 3, in the refrigerant circuit 20, the first
four-way switching valve 35 and the second four-way switching valve
36 are set to the first state and the third four-way switching
valve 37 is set to the second state. Moreover, the outdoor
expansion valve 34 is totally closed and the chiller expansion
valve 71 and the freezer expansion valve 83 are fully opened,
whereas the air-conditioning expansion valve 61 has its degree of
opening suitably adjusted. The first solenoid valve SV1 of the high
stage side hot gas passage 46 and the second solenoid valve SV2 of
the low stage side hot gas passage 89 are opened. In this state,
the first non-inverter compressor 31b and the second non-inverter
compressor 31c are operated.
[0176] The refrigerant discharged from the first non-inverter
compressor 31b and the refrigerant discharged from the second
non-inverter compressor 31c pass through the respective discharge
pipes 48b, 48c and merge with each other in the high-pressure pipe
45. The refrigerant after merging passes through the first four-way
switching valve 35 and the first gas pipe 50 and is sent to the
outdoor heat exchanger 32. In the outdoor heat exchanger 32, the
refrigerant dissipates heat to the outdoor air, thereby being
condensed. The refrigerant condensed in the outdoor heat exchanger
32 passes through the receiver 33 and flows through the first
liquid side connection piping 21 and then flows into the second
liquid side connection pipe 23.
[0177] On the other hand, part of the refrigerant discharged from
the first non-inverter compressor 31b and the second non-inverter
compressor 31c flows through the high stage side hot gas passage
46, the first low-pressure gas pipe 42, and the first gas side
connection piping 22 and then is distributed to the chiller side
branch gas pipe 22a and the freezer side branch gas pipe 22b.
[0178] The refrigerant flowing through the chiller side branch gas
pipe 22a flows into the chiller heat exchanger 72. In the chiller
heat exchanger 72, the refrigerant dissipates heat to the air in
the chiller showcase 13, thereby being condensed. At that time,
frost adhering to the chiller heat exchanger 72 is melted. The
refrigerant condensed in the chiller heat exchanger 72 passes
through the chiller expansion valve 71 and flows through the
chiller side branch liquid pipe 21a and then flows into the second
liquid side connection piping 23 and there merges with the
refrigerant from the outdoor unit 11.
[0179] The refrigerant flowing through the freezer side branch gas
pipe 22b passes through the low stage side hot gas passage 89 and
flows into the freezer heat exchanger 84 where the refrigerant
dissipates heat to the air in the freezer showcase 14, thereby
being condensed. At that time, frost adhering to the freezer heat
exchanger 84 is defrosted. The refrigerant condensed in the freezer
heat exchanger 84 passes through the freezer expansion valve 83,
the drain pan heater 82, the refrigerant heat exchanger 81, and
flows through the freezer side branch liquid pipe 21b and then
flows into the second liquid side connection piping 23 and there
merges with the refrigerant from the outdoor unit 11.
[0180] The refrigerant after merging in the second liquid side
connection piping 23 is supplied to the air-conditioning circuit
60. The refrigerant flowing into the air-conditioning circuit 60
has its pressure reduced when the refrigerant passes through the
air-conditioning expansion valve 61. Then, the refrigerant is
introduced into the air-conditioning heat exchanger 62. In the
air-conditioning heat exchanger 62, the refrigerant absorbs heat
from the indoor air, thereby being evaporated. In the
air-conditioning unit 12, the indoor air cooled by the
air-conditioning heat exchanger 62 is supplied into the store. The
refrigerant evaporated in the air-conditioning heat exchanger 62
passes through the second gas side connection piping 24 and flows
into the outdoor circuit 30 and then passes through the second gas
pipe 51, the first four-way switching valve 35, and the second
four-way switching valve 36 in sequence, and then passes through
the second low-pressure gas pipe 44, the second suction pipe 41b,
and the third suction pipe 41c, and then is sucked by the first
non-inverter compressor 31b and the second non-inverter compressor
31c. The first non-inverter compressor 31b and the second
non-inverter compressor 31c compress the sucked refrigerant and
discharge the refrigerant into the second discharge pipe 48b and
the third discharge pipe 48c, respectively.
[0181] As described above, in the defrosting operation shown in
FIG. 3, the chiller heat exchanger 72 and the freezer heat
exchanger 84 can be defrosted at the same time by the use of heat
absorbed by the indoor heat exchanger 62 and heat produced by
compressing the refrigerant by the first and second non-inverter
compressors 31b, 31c.
[0182] Here, FIG. 3 shows the operation using two compressors of
the first non-inverter compressor 31b and the second non-inverter
compressor 31c, but only any one of the compressors may be
operated.
[0183] Moreover, in the case of defrosting only the freezer heat
exchanger 84, it suffices to perform an operation in which the
chiller expansion valve 71 is closed to prevent the refrigerant
from flowing through the chiller showcase 13 in the operation state
shown in FIG. 3.
[0184] Next, the defrosting operation shown in FIG. 4 will be
described.
[0185] As shown in FIG. 4, in the refrigerant circuit 20, the first
four-way switching valve 35 and the second four-way switching valve
36 are set to the first state and the third four-way switching
valve 37 is set to the second state. Moreover, the outdoor
expansion valve 34 is totally closed and the chiller expansion
valve 71 is fully opened, whereas the freezer expansion valve 83
and the air-conditioning expansion valve 61 have their degrees of
opening suitably adjusted. The first solenoid valve SV1 of the high
stage side hot gas passage 46 is opened and the second solenoid
valve SV2 of the low stage side hot gas passage 89 is closed. In
this state, the first non-inverter compressor 31b, the second
non-inverter compressor 31c, and the booster compressor 85 are
operated.
[0186] The refrigerant discharged from the first non-inverter
compressor 31b and the refrigerant discharged from the second
non-inverter compressor 31c pass through the respective discharge
pipes 48b, 48c and merge with each other in the high-pressure pipe
45. The refrigerant after merging passes through the first four-way
switching valve 35 and the first gas pipe 50 and is sent to the
outdoor heat exchanger 32. In the outdoor heat exchanger 32, the
refrigerant dissipates heat to the outdoor air, thereby being
condensed. The refrigerant condensed in the outdoor heat exchanger
32 passes through the receiver 33 and flows through the first
liquid side connection piping 21 and then is distributed to the
second liquid side connection piping 23 and the freezer side branch
liquid pipe 21b.
[0187] The refrigerant flowing into the freezer heat circuit 80
from the freezer side branch gas pipe 21b passes through the
refrigerant heat exchanger 81 and the drain pan heater 82. Then,
when the refrigerant passes through the freezer expansion valve 83,
the refrigerant has its pressure reduced and then is introduced
into the freezer heat exchanger 84. In the freezer heat exchanger
84, the refrigerant absorbs heat from the air in the freezer
showcase 14 and evaporates. At that time, in the freezer heat
exchanger 84, the evaporation temperature of the refrigerant is set
to about -30.degree. C., for example. In the freezer showcase 14,
the air in the freezer showcase 14 cooled by the freezer heat
exchanger 84 is supplied, whereby the temperature in the freezer
showcase 14 is kept at about -20.degree. C., for example.
[0188] The refrigerant evaporated by the freezer heat exchanger 84
passes through the suction pipe 88 and then is sucked by the
booster compressor 85. The refrigerant compressed by the booster
compressor 85 passes through the discharge pipe 98 and the freezer
side branch gas pipe 22b and then flows into the first gas side
connection piping 22. At this time, the electronic expansion valve
87 disposed in the branch pipe 86 has the degree of opening
controlled and performs the function of an economizer. For this
reason, the discharge pressure of the booster compressor 85 is
increased to a level nearly equal to the discharge pressure of the
first non-inverter compressor 31b and the second non-inverter
compressor 31c.
[0189] On the other hand, part of the refrigerant discharged from
the first non-inverter compressor 31b and the second non-inverter
compressor 31c flows through the high stage side hot gas passage
46, the first low-pressure gas pipe 42, and the first gas side
connection piping 22 and then merges with the refrigerant from the
freezer unit 14 and then flows through the chiller side branch gas
pipe 22a.
[0190] The refrigerant flowing through the chiller side branch gas
pipe 22a flows into the chiller heat exchanger 72. In the chiller
heat exchanger 72, the refrigerant dissipates heat to the air in
the chiller showcase 13, thereby being condensed. At that time,
frost adhering to the chiller heat exchanger 72 is melted. The
refrigerant condensed in the chiller heat exchanger 72 passes
through the chiller expansion valve 71 and flows through the
chiller side branch liquid pipe 21a. Then, the refrigerant is
distributed, together with the refrigerant from the outdoor unit
11, to the second liquid side connection piping 23 and the freezer
side branch liquid pipe 21b.
[0191] The refrigerant flowing through the second liquid side
connection piping 23 is supplied to the air-conditioning circuit
60. When the refrigerant flowing into the air-conditioning circuit
60 passes through the air-conditioning expansion valve 61, the
refrigerant has its pressure reduced and then is introduced into
the air-conditioning heat exchanger 62. In the air-conditioning
heat exchanger 62, the refrigerant absorbs heat from the indoor
air, thereby being evaporated. In the air-conditioning unit 12, the
indoor air cooled by the air-conditioning heat exchanger 62 is
supplied into the store. The refrigerant evaporated in the
air-conditioning heat exchanger 62 passes through the second gas
side, connection piping 24 and flows into the outdoor heat
exchanger 30 and then passes through the second gas pipe 51, the
first four-way switching valve 35, and the second four-way
switching valve 36 in sequence and then passes through the second
low-pressure gas pipe 44, the second suction pipe 41b, and the
third suction pipe 41c and then is sucked by the first non-inverter
compressor 31b and the second non-inverter compressor 31c. The
first non-inverter compressor 31b and the second non-inverter
compressor 31c compress the sucked refrigerant and discharge the
compressed refrigerant into the second discharge pipe 48b and the
third discharge pipe 48c.
[0192] As described above, in the defrosting operation shown in
FIG. 4, the chiller heat exchanger 72 can be defrosted by the use
of heat absorbed by the indoor heat exchanger 62 and the freezer
heat exchanger 84 and heat produced by compressing the refrigerant
by the compressors 31b, 31c, and 85.
[0193] Here, FIG. 4 shows the operation using two compressors of
the first non-inverter compressor 31b and the second non-inverter
compressor 31c, but only any one of the compressors may be
operated.
[0194] (Heating Operation)
[0195] A heating operation is the operation of refrigerating air in
the chiller showcase 13 and the freezer showcase 14 and heating the
indoor air by the air-conditioning unit 12 to heat the interior of
the store.
[0196] As shown in FIG. 5, in the refrigerant circuit 20, the first
four-way switching valve 35 is set to the second state and the
second four-way switching valve 36 and the third four-way switching
valve 37 are set to the first state, respectively. Moreover, the
air-conditioning expansion valve 61 is fully opened, whereas the
outdoor expansion valve 34, the chiller expansion valve 71, and the
freezer expansion valve have their degrees of opening suitably
adjusted, and the first solenoid valve SV1 of the high stage side
hot gas passage 46 and the second solenoid valve SV2 of the low
stage side hot gas passage 89 are closed. In this state, the DC
inverter compressor 31a, the first non-inverter compressor 31b, the
second non-inverter compressor 31c, and the booster compressor 85
are operated.
[0197] The refrigerant discharged from the DC inverter compressor
31a, the first non-inverter compressor 31b, and the second
non-inverter compressor 31c passes through the high-pressure gas
pipe 45, the first four-way switching valve 35, the second gas pipe
51, and the second gas side connection piping 24 and then is
introduced into the air-conditioning heat exchanger 62 of the
air-conditioning circuit 60. In the air-conditioning circuit 60,
the refrigerant dissipates heat to the indoor air, thereby being
condensed. In the air-conditioning unit 12, the indoor air heated
by the air-conditioning heat exchanger 62 is supplied into the
store. The refrigerant condensed in the air-conditioning heat
exchanger 62 flows through the second liquid side connection piping
23 and then is distributed to the chiller side branch liquid pipe
21a, the freezer side branch liquid pipe 21b, and the first liquid
side connection piping 21.
[0198] The refrigerant flowing through the chiller side branch
liquid pipe 21a flows into the chiller showcase 13 and the
refrigerant flowing through the freezer side branch liquid pipe 21b
flows into the freezer showcase 14. In the chiller showcase 13 and
the freezer showcase 14, the airs in the showcases are cooled as is
the case with the cooling operation. The refrigerant evaporated in
the chiller heat exchanger 72 and the refrigerant evaporated in the
freezer heat exchanger 84 and then compressed by the booster
compressor 85 merge with each other in the first gas side
connection piping 22. The refrigerant flowing through the first gas
side connection piping 22 is distributed to the first suction pipe
41a and the second suction pipe 41b. Then, the distributed
refrigerants are sucked and compressed by the first non-inverter
compressor 31b and the second non-inverter compressor 31c,
respectively.
[0199] The refrigerant flowing through the first liquid side
connection piping 21 flows into the receiver 33 from the third
liquid pipe 55 and flows through the fourth liquid pipe 56 and has
its pressure reduced by the outdoor expansion valve 34. The
refrigerant having the pressure reduced by the outdoor expansion
valve 34 is introduced into the outdoor heat exchanger 32 and there
absorbs heat from the outdoor air, thereby being evaporated. The
refrigerant evaporated by the outdoor heat exchanger 32 passes
through the first four-way switching valve 35 and the second
four-way switching valve 36 and then passes through the second
low-pressure gas pipe 44 and the third suction pipe 41c and then is
sucked and compressed by the second non-inverter compressor
31c.
[0200] In this manner, at the time of the heating operation, the
refrigerant absorbs heat in the chiller heat exchanger 72, the
freezer heat exchanger 84, and the outdoor heat exchanger 32, and
dissipates heat in the air-conditioning heat exchanger 62. The
store is heated by the use of heat that the refrigerant absorbs
from the air in the chiller showcase 13 and the freezer showcase 14
in the chiller heat exchanger 72 and the freezer heat exchanger 84
and heat that the refrigerant absorbs from the outside air at the
outdoor heat exchanger 32.
[0201] In this regard, when a heating capacity becomes excessive in
the heating operation of using the outdoor heat exchanger 32 as an
evaporator, it is recommended to stop the second non-inverter
compressor 31c and to close the outdoor expansion valve 34 in the
state shown in FIG. 5 and to perform the heating operation in a
state where the refrigerant absorbs heat in the chiller heat
exchanger 72 and in the freezer heat exchanger 84 and dissipates
heat in the air-conditioning heat exchanger 62.
[0202] Moreover, when the heating capacity still becomes excessive,
it is recommended to perform the heating operation of using the
outdoor heat exchanger 32 as an evaporator and dissipating
excessive heat to the outside of the room by switching the second
four-way switching valve 36 to the second state and by switching
the outdoor expansion valve 34 to a fully opened state (at this
time, by stopping the second non-inverter compressor 31c).
[0203] (Defrosting Operation at the Time of the Heating
Operation)
[0204] As for a defrosting operation at the time of the heating
operation, a defrosting operation shown in FIG. 6 in which the
chiller heat exchanger 72 and the freezer heat exchanger 84 are
defrosted at the same time and a defrosting operation shown in FIG.
7 in which the chiller heat exchanger 72 is defrosted while the
freezer heat exchanger 84 performs a freezing operation can be
performed.
[0205] First, the defrosting operation shown in FIG. 6 will be
described. As shown in FIG. 6, in the refrigerant circuit 20, the
first four-way switching valve 35 and the third four-way switching
valve 37 are set to the second state and the second four-way
switching valve 36 is set to the first state. Moreover, the
air-conditioning expansion valve 61, the chiller expansion valve
71, and the freezer expansion valve 83 are fully opened, whereas
the outdoor expansion valve 34 has its degree of opening suitably
adjusted. The first solenoid valve SV1 of the high stage side hot
gas passage 46 and the second solenoid valve SV2 of the low stage
side hot gas passage 89 are opened. In this state, the first
non-inverter compressor 31b and the second non-inverter compressor
31c are operated.
[0206] The refrigerant discharged from the first non-inverter
compressor 31b and the refrigerant discharged from the second
non-inverter compressor 31c pass through the respective discharge
pipes 48b, 48c and merge with each other in the high-pressure pipe
45. The refrigerant after merging passes through the first four-way
switching valve 35, the second gas pipe 51, and the second gas side
connection piping 24 and is introduced into the outdoor heat
exchanger 32 of the air-conditioning circuit 60 where the
refrigerant dissipates heat to the indoor air, thereby being
condensed. In the air-conditioning unit 12, the indoor air heated
by the air-conditioning heat exchanger 62 is supplied into the
store. The refrigerant condensed in the air-conditioning heat
exchanger 62 flows through the second liquid side connection piping
23 and then flows into the first liquid side connection piping
21.
[0207] On the other hand, part of the refrigerant discharged from
the first non-inverter compressor 31b and the second non-inverter
compressor 31c flows through the high stage side hot gas passage
46, the first low-pressure gas pipe 42, and the first gas side
connection piping 22 and then are distributed to the chiller side
branch gas pipe 22a and the freezer side branch gas pipe 22b.
[0208] The refrigerant flowing through the chiller side branch gas
pipe 22a flows into the chiller heat exchanger 72. In chiller heat
exchanger 72, the refrigerant dissipates heat to the air in the
chiller showcase 13, thereby being condensed. At that time, frost
adhering to the chiller heat exchanger 72 is melted. The
refrigerant condensed in the chiller heat exchanger 72 passes
through the chiller expansion valve 71 and flows through the
chiller side branch liquid pipe 21a and then flows into the first
liquid side connection piping 21 and then merges with the
refrigerant from the air-conditioning unit 12.
[0209] The refrigerant flowing through the freezer side branch gas
pipe 22b passes through the low stage side hot gas passage 89 and
flows into the freezer heat exchanger 84. In the freezer heat
exchanger 84, the refrigerant dissipates heat to the air in the
freezer showcase 14, thereby being condensed. At that time, frost
adhering to the freezer heat exchanger 84 is melted. The
refrigerant condensed in the freezer heat exchanger 84 passes
through the freezer expansion valve 83, the drain pan heater 82,
the refrigerant heat exchanger 81, and flows through the freezer
side branch liquid pipe 21b and then flows into the first liquid
side connection piping 21 and then merges with the refrigerant from
the air-conditioning unit 12.
[0210] The refrigerant flowing through the first liquid side
connection piping 21 flows into the receiver 33 from the third
liquid pipe 55 and flows through the fourth liquid pipe 56 and has
its pressure reduced by the outdoor expansion valve 34. The
refrigerant having the pressure reduced by the outdoor expansion
valve 34 is introduced into the outdoor heat exchanger 32 and there
absorbs heat from the outdoor air, thereby being evaporated. The
refrigerant evaporated in the outdoor heat exchanger 32 passes
through the first four-way switching valve 35, the second four-way
switching valve 36, the second low-pressure gas pipe 44, the second
suction pipe 41b, and the third suction pipe 41c, and then is
sucked and compressed by the first non-inverter compressor 31b and
the second non-inverter compressor 31c.
[0211] As described above, in the defrosting operation shown in
FIG. 6, the chiller heat exchanger 72 and the freezer heat
exchanger 84 can be defrosted at the same time by the use of heat
absorbed by the outdoor heat exchanger 32 and heat produced by
compressing the refrigerant by the first and second non-inverter
compressors 31b, 31c.
[0212] Here, FIG. 6 shows the operation using two compressors of
the first non-inverter compressor 31b and the second non-inverter
compressor 31c, but only any one of the compressors may be
operated.
[0213] Moreover, in the case of defrosting only the freezer heat
exchanger 84, it suffices to perform an operation in which the
chiller expansion valve 71 is closed to prevent the refrigerant
from flowing through the chiller showcase 13 in the operation state
shown in FIG. 3.
[0214] Next, the defrosting operation shown in FIG. 7 will be
described.
[0215] As shown in FIG. 7, in the refrigerant circuit 20, the first
four-way switching valve 35 and the third four-way switching valve
37 are set to the second state and the second four-way switching
valve 36 is set to the first state. Moreover, the air-conditioning
expansion valve 61 and the chiller expansion valve 71 are fully
opened, whereas the freezer expansion valve 83 and the outdoor
expansion valve 34 have their degrees of opening suitably adjusted.
The first solenoid valve SV1 of the high stage side hot gas passage
46 is opened and the second solenoid valve SV2 of the low stage
side hot gas passage 89 is closed. In this state, the first
non-inverter compressor 31b, the second non-inverter compressor
31c, and the booster compressor 85 are operated.
[0216] The refrigerant discharged from the first non-inverter
compressor 31b and the refrigerant discharged from the second
non-inverter compressor 31c pass through the respective discharge
pipes 48b, 48c and merge with each other in the high-pressure pipe
45. The refrigerant after merging passes through the first four-way
switching valve 35, the second gas pipe 51, and the second gas side
connection piping 24 and is introduced into the outdoor heat
exchanger 32 where the refrigerant dissipates heat to the indoor
air, thereby being condensed. In the air-conditioning unit 12, the
indoor air heated by the air-conditioning heat exchanger 62 is
supplied into the store. The refrigerant condensed in the
air-conditioning heat exchanger 62 flows through the second liquid
side connection piping 23 and then is distributed to the freezer
side branch liquid pipe 21b and the first liquid side connection
piping 21.
[0217] The refrigerant flowing into the freezer circuit 80 from the
freezer side branch liquid pipe 21b passes through the refrigerant
heat exchanger 81 and the drain pan heater 82. When the refrigerant
passes through the freezer expansion valve 83, the refrigerant has
its pressure reduced and then is introduced into the freezer heat
exchanger 84. In the freezer heat exchanger 84, the refrigerant
absorbs heat from the air in the freezer showcase 14, thereby being
evaporated. At that time, in the freezer heat exchanger 84, the
evaporation temperature of the refrigerant is set to about
-30.degree. C., for example. In the freezer showcase 14, the air in
the freezer showcase 14 cooled by the freezer heat exchanger 84 is
supplied into the freezer showcase 14, whereby the temperature in
the freezer showcase 14 is kept at about -20.degree. C., for
example.
[0218] The refrigerant evaporated by the freezer heat exchanger 84
passes through the suction pipe 88 and then is sucked by the
booster compressor 85. The refrigerant compressed by the booster
compressor 85 passes through the discharge pipe 98 and the freezer
side branch gas pipe 22b and then flows into the first gas side
connection piping 22. At this time, the electronic expansion valve
87 disposed in the branch pipe 86 has the degree of opening
controlled and performs the function of an economizer. For this
reason, the discharge pressure of the booster compressor 85 is
increased to a level nearly equal to the discharge pressure of the
first non-inverter compressor 31b and the second non-inverter
compressor 31c.
[0219] On the other hand, part of the refrigerant discharged from
the first non-inverter compressor 31b and the second non-inverter
compressor 31c flows through the high stage side hot gas passage
46, the first low-pressure gas pipe 42, and the first gas side
connection piping 22 and then merges with the refrigerant from the
freezer unit 14 and then flows through the chiller side branch gas
pipe 22a.
[0220] The refrigerant flowing through the chiller side branch gas
pipe 22a flows into the chiller heat exchanger 72. In the chiller
heat exchanger 72, the refrigerant dissipates heat to the air in
the chiller showcase 13, thereby being condensed. At that time,
frost adhering to the chiller heat exchanger 72 is melted. The
refrigerant condensed in the chiller heat exchanger 72 passes
through the chiller expansion valve 71 and flows through the
chiller side branch liquid pipe 21a. Then, the refrigerant and is
distributed, together with the refrigerant from the
air-conditioning unit 12, to the freezer side branch liquid pipe
21b and the first liquid side connection piping 21.
[0221] The refrigerant flowing through the first liquid side
connection piping 21 flows into the receiver 33 from the third
liquid pipe 55 and flows through the fourth liquid pipe 56 and has
it pressure reduced by the outdoor expansion valve 34. The
refrigerant having its pressure reduced by the outdoor expansion
valve 34 is introduced into the outdoor heat exchanger 32. In the
outdoor heat exchanger 32, the refrigerant absorbs heat from the
outdoor air, thereby being evaporated. The refrigerant evaporated
in the outdoor heat exchanger 32 passes through the first four-way
switching valve 35, the second four-way switching valve 36, the
second low-pressure gas pipe 44, the second suction pipe 41b, and
the third suction pipe 41c, and then is sucked and compressed by
the first non-inverter compressor 31b and the second non-inverter
compressor 31c.
[0222] As described above, in the defrosting operation shown in
FIG. 7, the chiller heat exchanger 72 can be defrosted by the use
of heat absorbed by the outdoor heat exchanger 32 and the freezer
heat exchanger 84 and heat produced by compressing the refrigerant
by the compressors 31b, 31c.
[0223] Here, FIG. 7 shows the operation using two compressors of
the first non-inverter compressor 31b and the second non-inverter
compressor 31c, but only any one of the compressors may be
operated.
[0224] --Effect of Embodiment 1--
[0225] According to the refrigeration system 10 of this embodiment,
even if a defrosting mechanism such as an electric heater is not
provided in addition to the refrigerant circuit, both of the
chiller heat exchanger 72 and the freezer heat exchanger 84 can be
defrosted, so it is possible to prevent the construction of the
refrigeration system from becoming complex. Moreover, it is
possible not only to defrost both of the chiller heat exchanger 72
and the freezer heat exchanger 84 at the same time but also to
defrost only one of them. In this manner, the refrigeration system
10 of this embodiment can defrost the chiller heat exchanger 72 and
the freezer heat exchanger 84 individually and hence can respond to
a variety of patterns of the defrosting operations.
[0226] Further, in a refrigeration system of the related art in
which a freezer heat exchanger is defrosted by using a chiller heat
exchanger as a heat source, it is necessary to bring the chiller
heat exchanger and the freezer heat exchanger into a good balance
between heat absorption and heat dissipation at the time of the
defrosting operation. This presents the problem of imposing a
restriction on design. On the other hand, the refrigeration system
10 of this embodiment does not impose such a restriction on
design.
[0227] Still further, the chiller heat exchanger 72 and the freezer
heat exchanger 84 can be defrosted by the use of the heat absorbed
by the air-conditioning heat exchanger 62, the heat absorbed by the
outdoor heat exchanger 32, and the heat produced by compressing the
refrigerant by the compression mechanism 31, so the defrosting
operation can be performed efficiently.
[0228] Still further, when the frost adhering to the chiller heat
exchanger 72 and the freezer heat exchanger 84 is melted from
outside by the use of an electric heater, the temperature in the
refrigerator is easily increased. However, in this embodiment, the
frost adhering to the chiller heat exchanger 72 and the freezer
heat exchanger 84 is melted from inside by the use of heat of the
refrigerant, so an increase in the temperature in the refrigerator
can be prevented.
[0229] Still further, in the construction in which only the
operating pattern of defrosting the chiller heat exchanger 72 and
the freezer heat exchanger 84 at the same time can be performed,
when hot gas continues flowing through the heat exchanger defrosted
earlier, the temperature in the refrigerator is increased. However,
in this embodiment, the respective heat exchangers 72, 84 can be
defrosted individually, so when one of the heat exchangers 72, 84
is defrosted earlier, by stopping flowing the hot gas through the
heat exchanger, an increase in the temperature in the refrigerator
can be prevented with reliability.
[0230] Still further, while only the chiller heat exchanger 72 is
defrosted, the function of the economizer is performed in the
freezer showcase 14 to increase the discharge pressure of the
booster compressor 85. When the function of the economizer is not
used, a comparatively large pressure difference is developed
between the discharge pressure of the compression mechanism 31 of
the outdoor unit 11 and the discharge pressure of the booster
compressor 85, which raises a possibility that the booster
compressor 85 might be damaged. However, the use of the function of
the economizer can prevent such a problem.
[0231] In this embodiment, the description of the detailed flow of
the refrigerant in the refrigerant circuit 20 has been omitted, but
it is also possible to perform only the chilling/freezing operation
without performing the air-conditioning operation and to perform
only the air-conditioning operation without performing the
chilling/freezing operation.
Embodiment 2 of the Invention
[0232] A refrigeration system 10 of an embodiment 2, as shown in
FIG. 8, is an embodiment that is different from the embodiment 1 in
the construction of a part of the outdoor unit 11. Specifically,
the embodiment 2 is different from the embodiment .degree. in the
construction relating to the high stage side hot gas passage 46.
The hot gas introduction passage 46 of the embodiment 2 has its one
end connected to the high-pressure gas pipe 45 and has the other
end connected to the fourth port P4 of the third four-way switching
valve 37. Moreover, the check valve CV1 disposed in the first
connection pipe 43a in the embodiment 1 is not disposed in the
embodiment 2.
[0233] The other construction of the embodiment 2 is the same as
that of the embodiment 1.
[0234] --Operation--
[0235] In this embodiment 2, the cooling operation and the heating
operation can be also performed in the same way as in the
embodiment 1, and two or one of the chiller heat exchanger 72 and
the freezer heat exchanger 84 can be defrosted at the time of the
cooling operation or the heating operation.
[0236] At the time of the cooling operation, as shown in FIG. 9,
the first four-way switching valve 35, the second four-way
switching valve 36, and the third four-way switching valve 37 are
set to the first state, respectively. Moreover, the outdoor
expansion valve 34 is totally closed whereas the air-conditioning
expansion valve 61, the chiller expansion valve 71, and the freezer
expansion valve 83 have their degrees of opening suitably adjusted
and the second solenoid valve SV2 of the low stage side hot gas
passage 89 is closed. In this state, the DC inverter compressor
31a, the first non-inverter compressor 31b, the second non-inverter
compressor 31c, and the booster compressor 85 are actuated.
[0237] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 2. A refrigeration cycle is
performed in which the outdoor heat exchanger 32 is used as a
condenser and in which the air-conditioning heat exchanger 62, the
chiller heat exchanger 72, and the freezer heat exchanger 84 are
used as evaporators.
[0238] As for the defrosting operation at the time of the cooling
operation, the defrosting operation shown in FIG. 10 in which the
chiller heat exchanger 72 and the freezer heat exchanger 84 are
defrosted at the same time and the defrosting operation shown in
FIG. 11 in which the chiller heat exchanger 72 is defrosted while
the freezer heat exchanger 84 performs the cooling operation can be
performed.
[0239] At the time of the defrosting operation shown in FIG. 10,
the first four-way switching valve 35 and the second four-way
switching valve 36 are set to the first state and the third
four-way switching valve 37 is set to the second state. Moreover,
the outdoor expansion valve 34 is totally closed and the chiller
expansion valve 71 and the freezer expansion valve 83 are fully
opened, whereas the air-conditioning expansion valve 61 has its
degree of opening suitably adjusted. The second solenoid valve SV2
of the low stage side hot gas passage 89 is opened. In this state,
the first non-inverter compressor 31b and the second non-inverter
compressor 31c are operated.
[0240] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 3 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46, the third four-way switching valve 37, and the first
low-pressure gas pipe 42 to the chiller showcase 13 and the freezer
showcase 14. A refrigeration cycle is performed in which the
outdoor heat exchanger 32, the chiller heat exchanger 72, and the
freezer heat exchanger 84 are used as condensers and in which the
air-conditioning heat exchanger 62 is used as an evaporator.
[0241] At the time of the defrosting operation shown in FIG. 11,
the first four-way switching valve 35 and the second four-way
switching valve 36 are set to the first state and the third
four-way switching valve 37 is set to the second state. Moreover,
the outdoor expansion valve 34 is totally closed and the chiller
expansion valve 71 is fully opened, whereas the freezer expansion
valve 83 and the air-conditioning expansion valve 61 have their
degrees of opening suitably adjusted. The second solenoid valve SV2
of the low stage side hot gas passage 89 is closed. In this state,
the first non-inverter compressor 31b, the second non-inverter
compressor 31c, and the booster compressor 85 are operated.
[0242] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 4 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46, the third four-way switching valve 37, and the first
low-pressure gas pipe 42 to the chiller showcase 13. A
refrigeration cycle is performed in which the outdoor heat
exchanger 32 and the chiller heat exchanger 72 are used as
condensers and in which the air-conditioning heat exchanger 62 and
the freezer heat exchanger 84 are used as evaporators.
[0243] At the time of the heating operation, as shown in FIG. 12,
the first four-way switching valve 35 is set to the second state
and the second four-way switching valve 36 and the third four-way
switching valve 37 are set to the first state, respectively.
Moreover, the air-conditioning expansion valve 61 is fully opened
whereas the outdoor expansion valve 34, the chiller expansion valve
71, and the freezer expansion valve 83 have their degrees of
opening suitably adjusted. The second solenoid valve SV2 of the low
stage side hot gas passage 89 is closed. In this state, the DC
inverter compressor 31a, the first non-inverter compressor 31b, the
second non-inverter compressor 31c, and the booster compressor 85
are operated.
[0244] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 5. A refrigeration cycle is
performed in which the air-conditioning heat exchanger 62 is used
as a condenser and in which the outdoor heat exchanger 32, the
chiller heat exchanger 72, and the freezer heat exchanger 84 are
used as evaporators.
[0245] In this regard, when a heating capacity becomes excessive in
the heating operation of using the outdoor heat exchanger 32 as an
evaporator, it is recommended to stop the second non-inverter
compressor 31c and to close the outdoor expansion valve 34 in the
state shown in FIG. 12 and to perform the heating operation in a
state where the refrigerant absorbs heat in the chiller heat
exchanger 72 and in the freezer heat exchanger 84 and dissipates
heat in the air-conditioning heat exchanger 62.
[0246] Moreover, when the heating capacity still becomes excessive,
it is recommended to perform the heating operation of using the
outdoor heat exchanger 32 as an evaporator and dissipating
excessive heat to the outside of the room by switching the second
four-way switching valve 36 to the second state and by switching
the outdoor expansion valve 34 to a fully opened state (at this
time, by stopping the second non-inverter compressor 31c).
[0247] As for the defrosting operation at the time of the heating
operation, the defrosting operation shown in FIG. 13 in which the
chiller heat exchanger 72 and the freezer heat exchanger 84 are
defrosted at the same time and the defrosting operation shown in
FIG. 14 in which the chiller heat exchanger 72 is defrosted while
the freezer heat exchanger 84 performs the cooling operation can be
performed.
[0248] At the time of the defrosting operation shown in FIG. 13,
the first four-way switching valve 35 and the third four-way
switching valve 37 are set to the second state and the second
four-way switching valve 36 is set to the first state. Moreover,
the air-conditioning expansion valve 61, the chiller expansion
valve 71, and the freezer expansion valve 83 are fully opened,
whereas the outdoor expansion valve 34 has its degree of opening
suitably adjusted. The second solenoid valve SV2 of the low stage
side hot gas passage 89 is opened. In this state, the first
non-inverter compressor 31b and the second non-inverter compressor
31c are operated.
[0249] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 6 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46, the third four-way switching valve 37, and the first
low-pressure gas pipe 42 to the chiller showcase 13 and the freezer
showcase 14. A refrigeration cycle is performed in which the
air-conditioning heat exchanger 62, the chiller heat exchanger 72,
and the freezer heat exchanger 84 are used as condensers and in
which the outdoor heat exchanger 32 is used as an evaporator.
[0250] At the time of the defrosting operation shown in FIG. 14,
the first four-way switching valve 35 and the third four-way
switching valve 37 are set to the second state and the second
four-way switching valve 36 is set to the first state. Moreover,
the air-conditioning expansion valve 61 and the chiller expansion
valve 71 are fully opened, whereas the freezer expansion valve 83
and the outdoor expansion valve 34 have their degrees of opening
suitably adjusted. The second solenoid valve SV2 of the low stage
side hot gas passage 89 is closed. In this state, the first
non-inverter compressor 31b, the second non-inverter compressor
31c, and the booster compressor 85 are operated.
[0251] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 7 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46, the third four-way switching valve 37, and the first
low-pressure gas pipe 42 to the chiller showcase 13. A
refrigeration cycle is performed in which the air-conditioning heat
exchanger 62 and the chiller heat exchanger 72 are used as
condensers and in which the freezer heat exchanger 84 and the
outdoor heat exchanger 32 are used as evaporators.
[0252] --Effect of Embodiment 2--
[0253] The refrigeration system 10 of this embodiment 2, just as
with the embodiment 1, can respond to a variety of patterns of the
defrosting operations while preventing the construction of the
refrigeration system from becoming complex. Moreover, this
embodiment 2 is the same as the embodiment 1 also in that unlike a
refrigeration system of the related art in which a freezer heat
exchanger is defrosted by using a chiller heat exchanger as a heat
source, there is not a restriction in design such that it is
necessary to bring the chiller heat exchanger and the freezer heat
exchanger into a good balance between heat absorption and heat
dissipation at the time of the defrosting operation.
[0254] Furthermore, this embodiment 2 is the same as the embodiment
1 also: in that the chiller heat exchanger 72 and the freezer heat
exchanger 84 can be defrosted by the use of the heat absorbed by
the air-conditioning heat exchanger 62 and the outdoor heat
exchanger 32 and the heat produced by compressing the refrigerant
by the compression mechanism 31, so the defrosting operation can be
performed efficiently; and in that the frost adhering to the
chiller heat exchanger 72 and the freezer heat exchanger 84 can be
melted from inside by the heat of the refrigerant without using an
electric heater, whereby an increase in the chiller showcase 13 and
the freezer showcase 14 can be prevented.
Embodiment 3 of the Invention
[0255] A refrigeration system 10 of an embodiment 3 is an
embodiment in which one air-conditioning unit 12 and two freezer
units 14 are connected to the outdoor unit 11, as shown in FIG. 15,
in place of connecting one air-conditioning unit 12, one chiller
showcase 13, and one freezer showcase 14 to the outdoor unit 11.
Two freezer showcases 14 are connected in parallel to the outdoor
unit 11 via two freezer side branch liquid pipes 21b branched from
the first liquid side connection piping 21 and via two freezer side
branch gas pipes 22b branched from the first gas side connection
piping 22. In other words, in this embodiment 3, two freezer
circuits 80 each of which is provided with the freezer heat
exchanger 84 and the booster compressor 85 are connected in
parallel.
[0256] The other construction of the embodiment 3 is the same as
that of the embodiment 1.
[0257] --Operation--
[0258] This embodiment 3, just as with the embodiments 1 and 2, can
also perform the cooling operation and the heating operation and
can defrost two or one of the freezer heat exchangers 84 at the
time of the cooling operation and the heating operation.
[0259] At the time of the cooling operation, as shown in FIG. 16,
the first four-way switching valve 35, the second four-way
switching valve 36, and the third four-way switching valve 37 are
set to the first state, respectively. Moreover, the outdoor
expansion valve 34 is totally closed, whereas the air-conditioning
expansion valve 61, and each freezer expansion valve 83 have their
degrees of opening suitably adjusted and the second solenoid valve
SV2 of the low stage side hot gas passage 89 is closed. In this
state, the DC inverter compressor 31a, the first non-inverter
compressor 31b, the second non-inverter compressor 31c, and the
booster compressor 85 are actuated.
[0260] The refrigerant circulates through the refrigerant circuit
10 in the nearly same state as shown in FIG. 2. A refrigeration
cycle is performed in which the outdoor heat exchanger 32 is used
as a condenser and in which the air-conditioning heat exchanger 62
and the respective freezer heat exchangers 84 are used as
evaporators.
[0261] As for the defrosting operation at the time of the cooling
operation, the defrosting operation shown in FIG. 17 in which two
freezer heat exchangers 84 are defrosted at the same time and the
defrosting operation shown in FIG. 18 in which one freezer heat
exchanger 84 is defrosted while the other freezer heat exchanger 84
performs the refrigerating operation can be performed.
[0262] At the time of the defrosting operation shown in FIG. 17,
the first four-way switching valve 35 and the second four-way
switching valve 36 are set to the first state and the third
four-way switching valve 37 is set to the second state. Moreover,
the outdoor expansion valve 34 is totally closed and the respective
freezer expansion valves 83 are fully opened, whereas the
air-conditioning expansion valve 61 has its degree of opening
suitably adjusted. The first solenoid valve SV1 of the high stage
side hot gas passage 46 and the second solenoid valves SV2 of the
respective low stage side hot gas passages 89 are opened. In this
state, the first non-inverter compressor 31b and the second
non-inverter compressor 31c are operated.
[0263] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 3 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46 and the first low-pressure gas pipe 42 and then is branched to
two freezer side branch gas pipes 22b and that the branched
refrigerants then flow to the respective freezer showcases 14. A
refrigeration cycle is performed in which the outdoor heat
exchanger 32, the respective freezer heat exchangers 84 are used as
condensers and in which the air-conditioning heat exchanger 62 is
used as an evaporator.
[0264] The defrosting operation shown in FIG. 18 is an embodiment
in which the freezer showcase 14 shown on the upper side in the
drawing performs the defrosting operation. In the following
description, this freezer showcase 14 is referred to as a
defrosting side showcase and the freezer showcase 14 shown on the
lower side in the drawing is referred to as a refrigerating side
showcase.
[0265] In FIG. 18, the first four-way switching valve 35 and the
second four-way switching valve 36 are set to the first state and
the third four-way switching valve 37 is set to the second state.
Moreover, the outdoor expansion valve 34 is totally closed, whereas
the freezer expansion valve 83 of the refrigerating side showcase
and the air-conditioning expansion valve 61 have their degrees of
opening suitably adjusted and the freezer expansion valve 83 of the
defrosting side showcase is fully opened. The first solenoid valve
SV1 of the high stage side hot gas passage 46 is opened and the
second solenoid valve SV2 of the low stage side hot gas passage 89
of the defrosting side showcase is opened and the second solenoid
valve SV2 of the low stage side hot gas passage 89 of the
refrigerating side showcase is closed. In this state, the first
non-inverter compressor 31b, the second non-inverter compressor
31c, and the booster compressor 85 of the refrigerating side
showcase are operated.
[0266] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 4 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46 and the first low-pressure gas pipe 42 to freezer heat exchanger
84 of the defrosting side showcase. A refrigeration cycle is
performed in which the outdoor heat exchanger 32 and the freezer
heat exchanger 84 of the defrosting side showcase are used as
condensers and in which the air-conditioning heat exchanger 62 and
the freezer heat exchanger 84 of the refrigerating side showcase
are used as evaporators.
[0267] At the time of the heating operation, as shown in FIG. 19,
the first four-way switching valve 35 is set to the second state
and the second four-way switching valve 36 and the third four-way
switching valve 37 are set to the first state, respectively.
Moreover, the air-conditioning expansion valve 61 is fully opened
whereas the outdoor expansion valve 34 and the respective freezer
expansion valves 83 have their degrees of opening suitably
adjusted. The first solenoid valve SV1 of the high stage side hot
gas passage 46 and the second solenoid valve SV2 of the low stage
side hot gas passage 89 are closed. In this state, the DC inverter
compressor 31a, the first non-inverter compressor 31b, the second
non-inverter compressor 31c, and the respective booster compressors
85 are operated.
[0268] The refrigerant circulates through the refrigerant circuit
10 in the nearly same state as shown in FIG. 5. A refrigeration
cycle is performed in which the air-conditioning heat exchanger 62
is used as a condenser and in which the outdoor heat exchanger 32
and the respective freezer heat exchangers 84 are used as
evaporators.
[0269] When a heating capacity becomes excessive in the operation
of using the outdoor heat exchanger 32 as an evaporator, it is
recommended to stop the second non-inverter compressor 31c and to
close the outdoor expansion valve 34 in the state shown in FIG. 19
and to perform the heating operation in a state where the
refrigerant absorbs heat in the respective freezer heat exchangers
84 and dissipates heat in the air-conditioning heat exchanger
62.
[0270] Moreover, when the heating capacity still becomes excessive,
it is recommended to perform the operation of using the outdoor
heat exchanger 32 as an evaporator and dissipating the excessive
heat to the outside of the room by switching the second four-way
switching valve 36 to the second state and by switching the outdoor
expansion valve 34 to a fully opened state (at this time, by
stopping the second non-inverter compressor 31c).
[0271] As for the defrosting operation at the time of the heating
operation, the defrosting operation shown in FIG. 20 in which two
freezer heat exchangers 84 are defrosted at the same time and the
defrosting operation shown in FIG. 21 in which one freezer heat
exchanger 84 is defrosted while the other freezer heat exchanger 84
performs the refrigerating operation can be performed.
[0272] At the time of the defrosting operation shown in FIG. 20,
the first four-way switching valve 35 and the third four-way
switching valve 37 are set to the second state and the second
four-way switching valve 36 is set to the first state. Moreover,
the air-conditioning expansion valve 61 and the respective freezer
expansion valves 83 are fully opened, whereas the outdoor expansion
valve 34 has its degree of opening suitably adjusted. The first
solenoid valve SV1 of the high stage side hot gas passage 46 and
the second solenoid valves SV2 of the respective low stage side hot
gas passages 89 are opened. In this state, the first non-inverter
compressor 31b and the second non-inverter compressor 31c are
operated.
[0273] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 6 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46 and the first low-pressure gas pipe 42 and then is distributed
to two freezer side branch gas pipes 22b and that the distributed
refrigerants flow to the respective freezer showcases 14. A
refrigeration cycle is performed in which the air-conditioning heat
exchanger 62 and the respective freezer heat exchangers 84 are used
as condensers and in which the outdoor heat exchanger 32 is used as
an evaporator.
[0274] The defrosting operation shown in FIG. 21 is an embodiment
in which the freezer showcase 14 shown on the upper side in the
drawing performs the defrosting operation. At the time of this
defrosting operation, the first four-way switching valve 35 and the
third four-way switching valve 37 are set to the second state and
the second four-way switching valve 36 is set to the first state.
Moreover, the freezer expansion valve 83 of the refrigerating side
showcase and the outdoor expansion valve 34 have their degrees of
opening suitably adjusted, whereas the air-conditioning expansion
valve 61 and the freezer expansion valve 83 of the defrosting side
showcase are fully opened. The first solenoid valve SV1 of the high
stage side hot gas passage 46 is opened and the second solenoid
valve SV2 of the low stage side hot gas passage 89 of the
defrosting side showcase is opened, whereas the second solenoid
valve SV2 of the low stage side hot gas passage 89 of the
refrigerating side showcase is closed. In this state, the first
non-inverter compressor 31b, the second non-inverter compressor
31c, and the booster compressor 85 of the cooling side showcase are
operated.
[0275] The refrigerant circulates through the refrigerant circuit
10 in the same state as shown in FIG. 7 except that part of the
refrigerant discharged from the compression mechanism 31 of the
outdoor unit 10 flows through the high stage side hot gas passage
46 and the first low-pressure gas pipe 42 to the freezer heat
exchanger 84 of the defrosting side showcase. A refrigeration cycle
is performed in which the air-conditioning heat exchanger 62 and
the freezer heat exchanger 84 of the defrosting side showcase are
used as condensers and in which the freezer heat exchanger 84 of
the refrigerating side showcase and the outdoor heat exchanger 32
are used as evaporators.
[0276] --Effect of Embodiment 3--
[0277] The refrigeration system 10 of this embodiment 3, just as
with the embodiments 1 and 2, can respond to a variety of patterns
of the defrosting operations while preventing the construction of
the refrigeration system from becoming complex. In particular, even
when any one of the two freezer heat exchangers 84 is defrosted,
the other freezer heat exchangers 84 can perform the refrigerating
operation. Moreover, this embodiment 3 is the same as the
embodiments 1 and 2 also in that there is not a restriction in
design such that it is necessary to bring heat absorption and heat
dissipation in the chiller heat exchanger and the freezer heat
exchanger into a good balance at the time of the defrosting
operation.
[0278] Furthermore, this embodiment 3 is the same as the
embodiments 1 and 2 also: in that the freezer heat exchangers 84
can be defrosted by the use of the heat absorbed by the
air-conditioning heat exchanger 62 and the outdoor heat exchanger
32 and the heat produced by compressing the refrigerant by the
compression mechanism 31, so the defrosting operation can be
performed efficiently; and in that the frosts adhering to the
freezer heat exchangers 84 can be melted from inside by the heat of
the refrigerant without using an electric heater, which can prevent
an increase of the temperature in the chiller showcase 13 and the
freezer showcase 14.
Embodiment 4 of the Invention
[0279] A refrigeration system 10 of an embodiment 4 is basically
equivalent to that of the embodiment 1 in the construction of the
refrigerant circuit 20, but is different from that of the
embodiment 1 in the defrosting operation.
[0280] In this embodiment, in the period during which the freezer
heat exchanger 84 is defrosted, the refrigerant discharged from the
compression mechanism 31 of the outdoor circuit 30 is further
compressed by the booster compressor 85 and then the discharged
refrigerant is supplied to the freezer heat exchanger 84.
Specifically, part of the refrigerant discharged from the
compression mechanism 31 of the outdoor circuit 30 passes through
the low stage side hot gas passage 89 and is supplied to the
freezer heat exchanger 84 and the other part of the refrigerant is
compressed by the booster compressor 85 and then is merged with the
refrigerant flowing through the low stage side hot gas passage 89
from the compression mechanism 31 and the refrigerant after merging
is supplied to the freezer heat exchanger 84.
[0281] During this defrosting operation, part of the refrigerant
condensed by the freezer heat exchanger 84 is supplied for the
liquid injection into the booster compressor 85.
[0282] In this embodiment 4, it is assumed to think that the hot
gas introduction passage 46, 89 is divided into a first
introduction passage 96 for introducing the refrigerant discharged
from the compression mechanism 31 of the outdoor circuit 30 into
the booster compressor 85 and a second introduction passage 97 for
introducing the refrigerant discharged from the booster compressor
85 into the freezer heat exchanger 84. The second introduction
passage 97 is connected to the compression mechanism 31 of the
outdoor circuit 30 and the freezer heat exchanger 84 (the second
introduction passage 97 is a passage including the low stage side
hot gas passage 89). On the other hand, the first introduction
passage 96 is branched from second introduction passage 97 and is
connected to the booster compressor 85 so as to introduce part of
the refrigerant discharged from the compression mechanism 31 of the
outdoor circuit 30 into the booster compressor 85. Moreover, the
discharge pipe 98 of the booster compressor 85 is connected to the
compression mechanism 31 side of the outdoor circuit 30 in the
second introduction passage 97.
[0283] In this embodiment 4, the branch pipe 86 connected to the
low-pressure side passage 81b of the refrigerant heat exchanger 81
constructs a liquid injection passage 99 for introducing part of
the liquid refrigerant flowing out of the freezer heat exchanger 84
to the booster compressor 85 in the period during which the freezer
heat exchanger 84 is defrosted.
[0284] --Operation--
[0285] As for the operation of the embodiment 4, the defrosting
operation of the freezer heat exchanger 84 at the time of the
cooling operation will be described.
[0286] The refrigeration system 10 of the embodiment 4 switches
between a defrosting operation (first defrosting operation) shown
in FIG. 3 of the embodiment 1 and a defrosting operation (second
defrosting operation) shown in FIG. 22, which will be described
later. These two defrosting operations are switched according to
the detection temperature of the heat exchanger temperature sensor
90 disposed in the freezer heat exchanger 84.
[0287] In this refrigeration system 10, usually, the first
defrosting operation shown in FIG. 3 is performed. In the first
defrosting operation, as described above, the first non-inverter
compressor 31b and the second non-inverter compressor 31c of the
outdoor circuit 30 are operated, whereas the DC inverter compressor
31a and the booster compressor 85 are bought into a stop state and
both of the chiller heat exchanger 72 and the freezer heat
exchanger 84 are defrosted.
[0288] On the other hand, when the defrosting capacity of the
freezer heat exchanger 84 is not sufficient in the first defrosting
operation and hence the time required to defrost the freezer heat
exchanger 84 becomes long, the following second defrosting
operation is performed.
[0289] Specifically, when it takes a lot of time for the detection
temperature of the heat exchanger temperature sensor 90 to be
raised to a specified temperature in the first defrosting
operation, it is determined that the defrosting capacity of the
freezer heat exchanger 84 is not sufficient. As a result, the first
defrosting operation is shifted to the second defrosting
operation.
[0290] In this second defrosting operation, just as with the first
defrosting operation, in the refrigerant circuit 20, the first
four-way switching valve 35 and the second four-way switching valve
36 are set to the first state and the third four-way switching
valve 37 is set to the second state. Moreover, the outdoor
expansion valve 34 is totally closed and the chiller expansion
valve 71 and the freezer expansion valve 83 are fully opened,
whereas the air-conditioning expansion valve 61 has its degree of
opening suitably adjusted. The first solenoid valve SV1 of the high
stage side hot gas passage 46 and the second solenoid valve SV2 of
the low stage side hot gas passage 89 are opened. In this state,
the first non-inverter compressor 31b and the second non-inverter
compressor 31c are operated. Moreover, the electronic expansion
valve 87 of the branch pipe 86 as the liquid injection passage 99
has the degree of opening suitably adjusted and the booster
compressor 85 is actuated.
[0291] The refrigerant discharged in this state from the first
non-inverter compressor 31b and the refrigerant discharged from the
second non-inverter compressor 31c pass through the respective
discharge pipes 48b, 48c and merge with each other in the
high-pressure pipe 45. The refrigerant after merging passes through
the first four-way switching valve 35 and the first gas pipe 50 and
is sent to the outdoor heat exchanger 32. In the outdoor heat
exchanger 32, the refrigerant dissipates heat to the outdoor air,
thereby being condensed. The refrigerant condensed in the outdoor
heat exchanger 32 passes through the receiver 33 and flows through
the first liquid side connection piping 21 and then flows into the
second liquid side connection piping 23.
[0292] On the other hand, part of the refrigerant discharged from
the first non-inverter compressor 31b and the second non-inverter
compressor 31c flows through the high stage side hot gas passage
46, the first low-pressure gas pipe 42, and the first gas side
connection piping 22 and then is distributed to the chiller side
branch gas pipe 22a and the freezer side branch gas pipe 22b.
[0293] The refrigerant flowing through the chiller side branch gas
pipe 22a flows into the chiller heat exchanger 72 and there
dissipates heat to the air in the chiller showcase 13, thereby
being condensed. At that time, frost adhering to the chiller heat
exchanger 72 is melted. The refrigerant condensed in the chiller
heat exchanger 72 passes through the chiller expansion valve 71 and
flows through the chiller side branch liquid pipe 21a and then
flows into the second liquid side connection piping 23 and then
merges with the refrigerant from the outdoor unit 11.
[0294] The refrigerant flowing through the freezer side branch gas
pipe 22b passes through the second introduction passage 97
including the low stage side hot gas passage 89 and part of the
refrigerant flows into the freezer heat exchanger 84 and the other
part of the refrigerant passes through the first introduction
passage 96 and is sucked by the booster compressor 85.
[0295] The refrigerant compressed by the booster compressor 85
flows through the discharge pipe 98 and is sent to the low stage
side hot gas passage 89 and then is merged with the refrigerant
discharged from the compressor 31 of the outdoor circuit 30. Then,
the refrigerant merged in the low stage side hot gas passage 89
flows into the freezer heat exchanger 84. In other words, in the
freezer circuit 80, part of the refrigerant is compressed and
circulated by the booster compressor 85 and the input heat of the
booster compressor 85 is given to the refrigerant.
[0296] In the freezer heat exchanger 84, the refrigerant dissipates
heat to the air in the freezer showcase 14, thereby being
condensed. At that time, frost adhering to the freezer heat
exchanger 84 is melted. The refrigerant condensed in the freezer
heat exchanger 84 passes through the freezer expansion valve 83,
the drain pan heater 82, and the refrigerant heat exchanger 81 and
then flows through the freezer side branch liquid pipe 21b and then
flows into the second liquid side connection piping 23 and then
merges with the refrigerant from the outdoor unit 11.
[0297] At the time of this second defrosting operation, part of the
refrigerant compressed by the compression mechanism 31 of the
outdoor circuit 30 is further compressed by the booster compressor
85, so when this operation is continued, there is a possibility
that the temperature of the refrigerant discharged from the booster
compressor 85 is remarkably increased to cause the failure of the
booster compressor 85. For this reason, in the refrigeration system
10 of the embodiment 4, to prevent the failure of the booster
compressor 85, the operation of injecting liquid is performed.
[0298] Specifically, at the time of the second defrosting
operation, the degree of opening of the electronic expansion valve
87 is adjusted according to the temperature of the refrigerant
discharged from the booster compressor 85. For example, when the
temperature of the refrigerant discharged from the booster
compressor 85 is higher than a specified temperature, the degree of
opening of the electronic expansion valve 87 is made larger. As a
result, part of the refrigerant condensed by the freezer heat
exchanger 84 is passed through the branch pipe 86 of the liquid
injection passage 99 and is sent to the booster compressor 85. For
this reason, the refrigerant sucked into the booster compressor 85
is refrigerated. Thus, this can prevent the temperature of the
refrigerant discharged from the booster compressor 85 from being
abnormally increased.
[0299] On the other hand, the refrigerants merged with each other
in the second liquid side connection piping 23 are supplied to the
air-conditioning circuit 60. Subsequent operations are the same as
in the embodiment shown in FIG. 3. In other words, when the
refrigerant flowing into the air-conditioning circuit 60 passes
through the air-conditioning expansion valve 61, the refrigerant
has its pressure reduced and then is introduced into the
air-conditioning heat exchanger 62. In the air-conditioning heat
exchanger 62, the refrigerant absorbs heat from the indoor air,
thereby being evaporated. In the air-conditioning unit 12, the
indoor air refrigerated by the air-conditioning heat exchanger 62
is supplied into the store. The refrigerant evaporated in the
air-conditioning heat exchanger 62 passes through the second gas
side connection piping 24 and flows into the outdoor circuit 30 and
then passes through the second gas pipe 51, the first four-way
switching valve 35, and the second four-way switching valve 36 in
sequence, and then passes through the second low-pressure gas pipe
44, the second suction pipe 41b, and the third suction pipe 41c,
and then is sucked by the first non-inverter compressor 31b and the
second non-inverter compressor 31c. The first non-inverter
compressor 31b and the second non-inverter compressor 31c compress
the sucked refrigerant and discharge the compressed refrigerant
into the second discharge pipe 48b and the third discharge pipe
48c.
[0300] As described above, in the defrosting operation shown in
FIG. 22, the chiller heat exchanger 72 and the freezer heat
exchanger 84 can be defrosted at the same time by the use of heat
absorbed by the indoor heat exchanger 62 and heat produced by
compressing the refrigerant by the first and second non-inverter
compressors 31b, 31c of the outdoor circuit 30 and the booster
compressor 85 of the freezer circuit 80. Moreover, the same
operation as shown in FIG. 4 can be also performed and the
operation can be also performed in which only the freezer heat
exchanger 84 is defrosted by closing the chiller expansion valve
71.
[0301] In this regard, the defrosting operation of the freezer heat
exchanger 84 at the time of the heating operation will be
omitted.
[0302] --Effect of Embodiment 4--
[0303] In this embodiment 4, in addition to the same effect as in
the embodiment 1, the following effect can be produced.
[0304] That is, this embodiment 4 can switch the first defrosting
operation and the second defrosting operation and when the
defrosting capacity of the freezer heat exchanger 84 is not
sufficient in the first defrosting operation, the second defrosting
operation of operating also the booster compressor 85 is operated.
For this reason, according to the embodiment 4, heat to be given to
the refrigerant by the second defrosting operation can be increased
and hence the defrosting capacity of the freezer heat exchanger 84
can be increased. Thus, the freezer heat exchanger 84 can be
effectively defrosted by the second defrosting operation.
[0305] Moreover, in the embodiment 4, an abnormal increase in the
temperature of the refrigerant discharged from the booster
compressor 85 can be prevented by injecting liquid into the booster
compressor 85 during the second defrosting operation, so the
booster compressor 85 can be protected with reliability.
[0306] --Modification of Embodiment 4--
[0307] In the embodiment 4, the branch pipe 86 of the liquid
injection passage 99 is connected to the intermediate-pressure
position of the booster compressor 85, but this branch pipe 86 may
be connected to the first introduction passage 96 of the suction
pipe of the booster compressor 85.
[0308] Moreover, in the embodiment 4, an abnormal increase in the
temperature of the refrigerant discharged from the booster
compressor 85 can be prevented by injecting the liquid into the
booster compressor 85, but the operating capacity of the booster
compressor 85 may be controlled in place of injecting the liquid.
This can also prevent an abnormal increase in the temperature of
the refrigerant discharged from the booster compressor 85.
Embodiment 5 of the Invention
[0309] A refrigeration system 10 of an embodiment 5 is an
embodiment that is different from the refrigeration system 10 of
the embodiment 1 in a part of the construction of the refrigerant
circuit 20 and also in the construction of the hot gas introduction
passages 100, 102. The points in which this embodiment 5 is
different from the embodiment 1 will be mainly described below.
Here, in this embodiment 5, the sensors are omitted in the
drawing.
[0310] In this embodiment 5, the high-pressure introduction pipe 47
shown in FIG. 1 is not shown in the outdoor unit 11, but the
high-pressure introduction pipe 47 is provided, just as with the
embodiment 1, to introduce the high pressure of the refrigerant
circuit 20 into the fourth port P4 of the third four-way switching
valve 37.
[0311] In the freezer showcase 14, the refrigerant heat exchanger
81 is not provided but the gas side piping 110 (88) of the freezer
heat exchanger 84 is connected to the suction side of the booster
compressor 85. An oil separator 120 is disposed in the discharge
pipe 98 of the booster compressor 85 and an oil return pipe 122
having a capillary tube 121 is connected between the oil separator
120 and the suction pipe 111 of the booster compressor 85.
Moreover, a bypass piping 125 bypassing the booster compressor 85
when the booster compressor 85 fails is connected to the suction
pipe 111 and the discharge pipe 98 of the booster compressor 85.
This bypass piping 125 has a check valve CV10 disposed therein.
[0312] As for a feature of this embodiment 5, unlike the embodiment
1, the hot gas introduction passage 100 is not disposed
individually on the higher stage side and the lower stage side but
is constructed of one piping connected to the discharge line
(high-pressure gas pipe) 45 of the compression mechanism 31 of the
outdoor unit 11 and to the gas side piping 110 of the freezer heat
exchanger 84. This hot gas introduction passage 100 has an
electronic expansion valve 101 disposed therein as a flow control
mechanism.
[0313] Moreover, it is also recommended to connect the hot gas
introduction passage 100 not only to the freezer heat exchanger 84
but also, as shown by a broken line in FIG. 23, to the gas side
piping 112 of the chiller heat exchanger 72 by a branch pipe (hot
gas introduction passage) 102 disposed in the hot gas introduction
passage 100 and to provide a switching mechanism 103 such as a
three-way valve capable of switching or selecting a hot gas flow to
the freezer heat exchanger 84 and a hot gas flow to the chiller
heat exchanger 72. With this, both of the chiller heat exchanger 72
and the freezer heat exchanger 84 can be defrosted at the same time
or only one of them can be defrosted. Thus, just as with the
respective embodiments, this embodiment 5 can defrost the
respective heat exchangers 72, 84 individually and hence can
respond to a variety of patterns of defrosting operations.
[0314] For example, when the freezer heat exchanger 84 is
defrosted, part of the refrigerant discharged from the compression
mechanism 31 of the outdoor unit 11 flows through the hot gas
introduction passage 100 and is introduced into the freezer heat
exchanger 84. In the freezer heat exchanger 84, the frost adhering
to the freezer heat exchanger 84 is melted by the heat of the
high-pressure refrigerant. The refrigerant is evaporated in the
chiller heat exchanger 72, the air-conditioning heat exchanger 62,
or the outdoor heat exchanger 32 and then is sucked by the
compressor mechanism 31. At that time, when the electronic
expansion valve 101 is fully opened, the flow of refrigerant is
large, so it can be thought that the frost adhering to the freezer
heat exchanger 84 is melted around a coil at a stretch, whereby the
blocks of the frost not melted around the coil will be dropped from
the coil on goods for sale. However, when the flow of the
refrigerant is controlled by adjusting the degree of opening of the
electronic expansion valve 101, it is possible to melt the frost
slowly around the coil and hence to prevent the frost from dropping
on the goods for sale.
[0315] The operation at the time of the cooling operation and the
heating operation in this embodiment is nearly the same as those in
the respective embodiments described above and hence the
description of the operation will be omitted here.
Other Embodiments
[0316] The above-mentioned embodiments may be constructed in the
following manner. For example, in the embodiments 1 and 2, an
example has been described in which one air-conditioning unit 12,
one chiller showcase 13, and one freezer showcase 14 are connected,
but the numbers of the air-conditioning unit 12, the chiller
showcase 13, and the freezer showcase 14 may be changed as
appropriate.
[0317] Moreover, in the embodiment 3, an example has been described
in which one air-conditioning unit 12 and two freezer showcases 14
are connected to the outdoor unit 11, but three or more freezer
showcases 14 may be connected.
[0318] Moreover, in any one of the embodiments 1 to 3, when the
store is air-conditioned by a dedicated air-conditioner, the
refrigeration system 10 of each embodiment does not need to be
provided with the air-conditioning unit 12.
[0319] Further, while the compression mechanism 31 of the outdoor
unit 11 is constructed of three compressors 31a, 31b, and 31c in
the respective embodiments, the number of compressors may be
changed and when the air-conditioning unit 12 is not provided, the
number of compressor may be one.
[0320] Still further, the embodiment 4 is an embodiment in which
the effect of the defrosting operation is enhanced by utilizing the
booster compressor 85 at the time of defrosting the freezer heat
exchanger 84 in the embodiment 1. The same idea can be applied also
to the embodiment 2 and the embodiment 3. Still further, in the
embodiment 4, at the time of the second defrosting operation, the
refrigerant discharged from the compressor mechanism 31 of the
outdoor unit 11 is circulated while part of the refrigerant is
supplied to the freezer heat exchanger 84 and while the other part
of the refrigerant is supplied to the booster compressor 85.
However, the entire refrigerant discharged from the compressor
mechanism 31 may be supplied to and compressed by the booster
compressor 85 and then be supplied to the freezer heat exchanger
84.
[0321] The above-mentioned embodiments have been described by way
of essentially preferable examples and do not intend to limit the
present invention, its applications, or the scope of its usage.
INDUSTRIAL APPLICABILITY
[0322] As described above, the present invention is useful for a
refrigeration system having a refrigerant circuit of a vapor
compression type refrigeration cycle of the construction in which
plural lines of refrigeration circuits each having a refrigeration
heat exchanger are connected to an outdoor circuit provided with an
outdoor heat exchanger and a compression mechanism and in which an
auxiliary compressor is connected in series to the refrigeration
heat exchanger in at least one line of refrigeration circuit.
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