U.S. patent application number 10/570879 was filed with the patent office on 2007-02-01 for supercooling apparatus.
Invention is credited to Azuma Kondo, Satoru Sakae, Iwao Shinohara, Masaaki Takegami, Kenji Tanimoto.
Application Number | 20070022777 10/570879 |
Document ID | / |
Family ID | 35503161 |
Filed Date | 2007-02-01 |
United States Patent
Application |
20070022777 |
Kind Code |
A1 |
Takegami; Masaaki ; et
al. |
February 1, 2007 |
Supercooling apparatus
Abstract
A subcooling unit (200) includes a refrigerant passage (205)
connected to liquid side communication pipes (21, 22) of a
refrigerating apparatus (10). When a subcooling compressor (221) is
operated, subcooling refrigerant circulates in the subcooling
refrigerant circuit (220) to perform a refrigeration cycle, thereby
cooling refrigerant of the refrigerating apparatus (10) which flows
in the refrigerant passage (205). A controller (240) of the
subcooling unit (200) receives the detection value of a suction
pressure sensor (234) and a refrigerant temperature sensor (236).
The controller (240) utilizes input signals from the sensors (234,
236) to control driving operation of the subcooling compressor
(221) on the basis of information obtained within the subcooling
unit (200). Thus, the operation of the subcooling compressor (221)
can be controlled without sending and receiving a singal to and
from the refrigerating apparatus (10) to which the subcooling unit
(200) is incorporated.
Inventors: |
Takegami; Masaaki; (Osaka,
JP) ; Tanimoto; Kenji; (Osaka, JP) ; Sakae;
Satoru; (Osaka, JP) ; Shinohara; Iwao; (Osaka,
JP) ; Kondo; Azuma; (Osaka, JP) |
Correspondence
Address: |
BIRCH STEWART KOLASCH & BIRCH
PO BOX 747
FALLS CHURCH
VA
22040-0747
US
|
Family ID: |
35503161 |
Appl. No.: |
10/570879 |
Filed: |
June 9, 2005 |
PCT Filed: |
June 9, 2005 |
PCT NO: |
PCT/JP05/10584 |
371 Date: |
March 7, 2006 |
Current U.S.
Class: |
62/498 ;
62/332 |
Current CPC
Class: |
F25B 40/02 20130101;
F25B 2600/23 20130101; F25B 2700/2103 20130101; F25B 2700/2106
20130101; F25B 13/00 20130101; F25B 2400/22 20130101; F25B 7/00
20130101; F25B 2600/0251 20130101; F25B 2313/02331 20130101 |
Class at
Publication: |
062/498 ;
062/332 |
International
Class: |
F25B 1/00 20060101
F25B001/00; F25B 25/00 20060101 F25B025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 11, 2004 |
JP |
2004-174288 |
Claims
1. A subcooling apparatus which is incorporated to a refrigerating
apparatus (10) that performs a refrigeration cycle by circulating
heat source side refrigerant between a heat source unit (11) and a
utility unit (12, 13, 14) connected to each other by means of
communication pipes and which cools the heat source side
refrigerant in the refrigerating apparatus (10) sent from the heat
source unit (11) to the utility unit (12, 13, 14), the subcooling
apparatus, comprising: a refrigerant passage (205) connected to
liquid side communication pipes (21, 22) of the refrigerating
apparatus (10); a cooling fluid circuit (220) in which cooling
fluid flows; a subcooling heat exchanger (210) for cooling the heat
source side refrigerant in the refrigerant passage (205) by heat
exchange with the cooling fluid; and control means (240) for
controlling a flowing state of the cooling fluid in the cooling
fluid circuit (220) according to a flowing state of the heat source
side refrigerant in the refrigerant passage (205).
2. The subcooling apparatus of claim 1, wherein the cooling fluid
circuit is composed of a subcooling refrigerant circuit (220), and
the subcooling refrigerant circuit (220) includes a subcooling
compressor (221) and performs a refrigeration cycle by circulating
subcooling refrigerant as the cooling fluid.
3. The subcooling apparatus of claim 2, wherein the control means
(240) controls a circulation state of the subcooling refrigerant in
the subcooling refrigerant circuit (220) by controlling operation
of the subcooling compressor (221).
4. The subcooling apparatus of claim 3, wherein the control means
(240) detects a direction in which the heat source side refrigerant
flows in the refrigerant passage (205) and a state in which the
heat source side refrigerant flows or does not flow in refrigerant
passage (205) in operation of the subcooling compressor (221) as
the flowing state of the heat source side refrigerant, and the
control means (240) allows the subcooling compressor (221) to
continue operating in a state that the heat source side refrigerant
flows from the heat source unit (11) towards the utility unit (12,
13, 14) in the refrigerant passage (205) or stops the operation of
the subcooling compressor (221) in a state that the heat source
side refrigerant flows from the utility unit (12, 13, 14) towards
the heat source unit (11) in the refrigerant passage (205) or in a
state that the heat source side refrigerant does not flow in the
refrigerant passage (205).
5. The subcooling apparatus of claim 4 wherein the control means
(240) activates the subcooling compressor (221) after a
predetermined time period elapses from a time point when the
subcooling compressor (221) is stopped.
6. The subcooling apparatus of any one of claims 3, 4, and 5,
further comprising: refrigerant temperature detection means (236)
for detecting temperature of the heat source side refrigerant at a
part of the refrigerant passage (205) nearer the utility unit (12,
13, 14) than the subcooling heat exchanger (210), wherein the
control means (240) judges the flowing state of the heat source
side refrigerant on the basis of variation in detection value of
the refrigerant temperature detection means (236) from a time point
when the subcooling compressor (221) is activated.
7. The subcooling apparatus of any one of claims 3, 4, and 5,
further comprising: refrigerant temperature detection means (236)
for detecting temperature of the heat source side refrigerant at a
part of the refrigerant passage (205) nearer the utility unit (12,
13, 14) than the subcooling heat exchanger (210); and evaporation
temperature detection means (234) for detecting evaporation
temperature of the subcooling refrigerant in the subcooling heat
exchanger (210), wherein the control means (240) judges the flowing
state of the heat source side refrigerant on the basis of a
detection value of the refrigerant temperature detection means
(236) and a detection value of the evaporation temperature
detection means (234).
8. The subcooling apparatus of any one of claims 3, 4, and 5,
further comprising: first refrigerant temperature detection means
(237) for detecting temperature of the heat source side refrigerant
at a part of the refrigerant passage (205) nearer the utility unit
(12, 13, 14) than the subcooling heat exchanger (210); and second
refrigerant temperature detection means (238) for detecting
temperature of the heat source side refrigerant at a part of the
refrigerant passage (205) nearer the heat source unit (11) than the
subcooling heat exchanger (210), wherein the control means (240)
judges the flowing state of the heat source side refrigerant on the
basis of a detection value of the first refrigerant temperature
detection means (237) and a detection value of the second
refrigerant temperature detection means (238).
9. The subcooling apparatus of any one of claims 1, 2, and 3,
wherein a flow meter (251) is provided at the refrigerant passage
(205) for detecting a flow rate of the heat source side
refrigerant, and the control means (240) uses a detection value of
the flow meter (251) as a flowing state indication vale that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether the flow of the cooling fluid
should be continued or stopped in a state that the cooling fluid
flows in the cooling fluid circuit (220).
10. The subcooling apparatus of any one of claims 1, 2, and 3,
further comprising: first refrigerant temperature detection means
(237) for detecting temperature of the heat source side refrigerant
at a part of the refrigerant passage (205) nearer the utility unit
(12, 13, 14) than the subcooling heat exchanger (210); and second
refrigerant temperature detection means (238) for detecting
temperature of the heat source side refrigerant at a part of the
refrigerant passage (205) nearer the heat source unit (11) than the
subcooling heat exchanger (210), wherein the control means (240)
uses a difference between a detection value of the first
refrigerant temperature detection means (237) and a detection value
of the second refrigerant temperature detection means (238) as a
flowing state indication value that indicates the flowing state of
the heat source side refrigerant, and the control means (240)
determines, on the basis of the flowing state indication value,
whether the flow of the cooling fluid should be continued or
stopped in a state that the cooling fluid flows in the cooling
fluid circuit (220).
11. The subcooling apparatus of any one of claims 1, 2, and 3,
further comprising: refrigerant temperature detection means (236)
for detecting temperature of the heat source side refrigerant at a
part of the refrigerant passage (205) nearer the utility unit (12,
13, 14) than the subcooling heat exchanger (210), wherein the
control means (240) uses variation in detection value of the
refrigerant temperature detection means (236) as a flowing state
indication value that indicates the flowing state of the heat
source side refrigerant, and the control means (240) determines, on
the basis of the flowing state indication value, whether the flow
of the cooling fluid should be continued or stopped in a state that
the cooling fluid flows in the cooling fluid circuit (220).
12. The subcooling apparatus of any one of claims 1, 2, and 3,
wherein the cooling fluid circuit (220) includes inlet side fluid
temperature detection means (252) for detecting temperature of the
cooling fluid at an inlet of the subcooling heat exchanger (210)
and outlet side fluid temperature detection means (253) for
detecting temperature of the cooling fluid at an outlet of the
subcooling heat exchanger (210), and the control means (240) uses a
difference between a detection value of the inlet side fluid
temperature detection means (252) and a detection value of the
outlet side fluid temperature detection means (253) as a flowing
state indication value that indicates the flowing state of the heat
source side refrigerant, and the control means (240) determines, on
the basis of the flowing state indication value, whether the flow
of the cooling fluid should be continued or stopped in a state that
the cooling fluid flows in the cooling fluid circuit (220).
13. The subcooling apparatus of claim 2 or 3, wherein the
subcooling refrigerant circuit (220) includes evaporation pressure
detection means (234) for detecting evaporation pressure of the
subcooling refrigerant in the subcooling heat exchanger (210), and
the control means (240) uses a detection value of the evaporation
pressure detection means (234) as a flowing state indication value
that indicates the flowing state of the heat source side
refrigerant, and the control means (240) determines, on the basis
of the flowing state indication value, whether circulation of the
subcooling fluid should be continued or stopped in a state that the
subcooling fluid circulates in the cooling fluid circuit (220).
14. The subcooling apparatus of claim 2 or 3, further comprising:
refrigerant temperature detection means (236) for detecting
temperature of the heat source side refrigerant at a part of the
refrigerant passage (205) nearer the utility unit (12, 13, 14) than
the subcooling heat exchanger (210); and evaporation temperature
detection means (234) for detecting evaporation temperature of the
subcooling refrigerant in the subcooling heat exchanger (210),
wherein the control means (240) uses a difference between a
detection value of the refrigerant temperature detection means
(236) and a detection value of the evaporation temperature
detection means (234) as a flowing state indication value that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether circulation of the subcooling
refrigerant should be continued or stopped in a state that the
subcooling refrigerant circulates in the subcooling refrigerant
circuit (220).
15. The subcooling apparatus of any one of claims 1, 2 and 3,
further comprising: refrigerant temperature detection means (236)
for detecting temperature of the heat source side refrigerant at a
part of the refrigerant passage (205) nearer the utility unit (12,
13, 14) than the subcooling heat exchanger (210), wherein the
control means (240) uses a detection value of the refrigerant
temperature detection means (236) as a flowing state indication
value that indicates the flowing state of the heat source side
refrigerant, and the control means (240) determines, on the basis
of the flowing state indication value, whether the flow of the
cooling fluid should be started or kept stopping in a state that
the cooling fluid stops flowing in the cooling fluid circuit
(220).
16. The subcooling apparatus of any one of claims 1, 2 and 3,
further comprising: refrigerant temperature detection means (236)
for detecting temperature of the heat source side refrigerant at a
part of the refrigerant passage (205) nearer the utility unit (12,
13, 14) than the subcooling heat exchanger (210), wherein the
control means (240) uses variation in detection value of the
refrigerant temperature detection means (236) as a flowing state
indication value that indicates the flowing state of the heat
source side refrigerant, and the control means (240) determines, on
the basis of the flowing state indication value, whether the flow
of the cooling fluid should be started or kept stopping in a state
that the cooling fluid stops flowing in the cooling fluid circuit
(220).
17. The subcooling apparatus of claim 2 and 3, further comprising:
outside air temperature detection means (231) for detecting
temperature of outside air; and refrigerant temperature detection
means (236) for detecting temperature of the heat source side
refrigerant at a part of the refrigerant passage (205) nearer the
utility unit (12, 13, 14) than the subcooling heat exchanger (210),
wherein the control means (240) uses a difference between a
detection value of the refrigerant temperature detection means
(236) and a detection value of the outside air temperature
detection means (231) as a flowing state indication value that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether the flow of the subcooling
refrigerant should be started or kept stopping in a state that the
subcooling refrigerant stops flowing in the subcooling refrigerant
circuit (220).
18. A subcooling apparatus which is incorporated to a refrigerating
apparatus (10) that performs a refrigeration cycle by circulating
heat source side refrigerant between a heat source unit (11) and a
utility unit (12, 13, 14) connected to each other by means of
communication pipes and which cools the heat source side
refrigerant in the refrigerating apparatus (10) sent from the heat
source unit (11) to the utility unit (12, 13, 14), wherein the heat
source unit (11) of the refrigerating apparatus (10) performs heat
exchange between the heat source side refrigerant and outdoor air,
the subcooling apparatus comprising: a refrigerant passage (205)
connected to liquid side communication pipes (21, 22) of the
refrigerating apparatus (10); a cooling fluid circuit (220) in
which cooling fluid flows; a subcooling heat exchanger (210) for
cooling the heat source side refrigerant in the refrigerant passage
(205) by heat exchange with the cooling fluid; outside air
temperature detection means (231) for detecting temperature of
outside air; and control means (240) for controlling a flowing
state of the cooling fluid in the cooling fluid circuit (220)
according to a detection value of the outside air temperature
detection means (231).
19. The subcooling apparatus of claim 18, wherein the cooling fluid
circuit is composed of a subcooling refrigerant circuit (220), and
the subcooling refrigerant circuit (220) includes a subcooling
compressor (221) and performs a refrigeration cycle by circulating
the subcooling refrigerant as the cooling fluid.
20. The subcooling apparatus of claim 18 or 19, wherein the control
means (240) determines, on the basis of a detection value of the
outside air temperature detection means (231), whether the flow of
the cooling fluid should be continued or stopped in a state that
the cooling fluid flows in the cooling fluid circuit (220).
21. The subcooling apparatus of claim 18 or 19, wherein the control
means (240) determines, on the basis of a detection value of the
outside air temperature detection means (231), whether the flow of
the cooling fluid should be started or kept stopping in a state
that the cooling fluid does not flow in the cooling fluid circuit
(220).
22. The subcooling apparatus of claim 2 or 19, further comprising:
heat radiation heat exchanger (222) connected to the subcooling
refrigerant circuit (220) for performing heat exchange between the
subcooling refrigerant and outside air; and outdoor fan (230) for
supplying outdoor air to the heat radiation heat exchanger (222),
wherein the subcooling refrigerant circuit (220) is capable of
performing natural circulation operation that allows the subcooling
refrigerant to naturally circulate by operating the outdoor fan
(230) in non-operation of the subcooling compressor (221), and the
control means (240) allows the subcooling refrigerant circuit (220)
to perform the natural circulation operation by activating the
outdoor fan (230) in order to start circulation of the subcooling
refrigerant, and the control means (240) determines whether the
subcooling compressor (221) should be activated or kept stopping
according to the flowing state of the heat source side refrigerant
in the refrigerant passage (205) in natural circulation operation.
Description
TECHNICAL FIELD
[0001] The present invention relates to a subcooling apparatus,
which is incorporated to a refrigerating apparatus including a heat
source unit and a utility unit, for cooling refrigerant sent
through liquid side communication pipes from the heat source unit
to the utility unit.
BACKGROUND ART
[0002] Subcooling apparatuses are known which are incorporated to
refrigerating apparatuses for the purpose of increasing cooling
power so as to cool refrigerant sent from a heat source unit to a
utility unit of the refrigerating apparatuses.
[0003] A subcooling apparatus disclosed in, for example, Patent
Document 1 is incorporated to an air conditioner including an
outdoor unit and an indoor unit. Specifically, the subcooling
apparatus, which includes a subcooling refrigerant circuit, is
provided in the middle of a liquid side communication pipe that
connects the outdoor unit and the indoor unit. The subcooling unit
performs a refrigeration cycle by circulating refrigerant of the
subcooling refrigerant circuit to cool by an evaporator of the
subcooling refrigerant circuit the refrigerant of the air
conditioner sent from the liquid side communication pipe. The
subcooling apparatus cools the liquid refrigerant sent from the
outdoor unit to the indoor unit of the air conditioner, thereby
lowering the enthalpy of the liquid refrigerant sent to the indoor
unit to increase the cooling capacity.
[0004] As described above, the subcooling apparatus is provided for
increasing the cooling power by assisting the refrigerating
apparatus of an air conditioner or the like. Accordingly, operation
of only the subcooling apparatus in non-operation of the
refrigerating apparatus is nonsense. The operation of the
subcooling apparatus in the condition that the refrigerating
apparatus operates as a heat pump for heating operation of the air
conditioner is also nonsense. In this way, it is necessary for
determining whether or not the subcooling apparatus should be
operated to know the operation state of the refrigerating apparatus
to which the subcooling apparatus is incorporated.
[0005] Under the circumstances, in the conventional subcooling
apparatus disclosed in Patent Document 1, a control section of the
subcooling apparatus is connected to a control section of the air
conditioner to form one control system. The control section of the
subcooling apparatus receives a signal indicating an operation
state of the air conditioner from the control section of the air
conditioner. Then, the subcooling apparatus performs operation
control on the basis of the signal input from the control section
of the air conditioner.
Patent Document 1: Japanese Patent Application Laid Open
Publication No. 10-185333A
SUMMARY OF THE INVENTION
Problems that the Invention is to Solve
[0006] As described above, the conventional subcooling apparatus
sends and receives a signal to and from the refrigerating apparatus
to which the subcooling apparatus is incorporated. For this reason,
in order to incorporate the subcooling apparatus to the
refrigerating apparatus, wiring for transmitting a singal
therebetween is necessary, thereby complicating installation of the
subcooling apparatus. Further, mis-wiring may be involved in
installation of the subcooling apparatus, resulting in invitation
of troubles caused due to such miss-installation.
[0007] The present invention has been made in view of the foregoing
and has its objectives of enabling operation control of a
subcooling apparatus without sending and receiving a signal to and
from a refrigerating apparatus to which the subcooling apparatus is
incorporated, of simplifying installation of the subcooling
apparatus, and of obviating troubles caused due to human errors at
installation.
MEANS FOR SOLVING THE PROBLEMS
[0008] The first invention directs to a subcooling apparatus which
is incorporated to a refrigerating apparatus (10) that performs a
refrigeration cycle by circulating heat source side refrigerant
between a heat source unit (11) and a utility unit (12, 13, 14)
connected to each other by means of communication pipes and which
cools the heat source side refrigerant in the refrigerating
apparatus (10) sent from the heat source unit (11) to the utility
unit (12, 13, 14). The subcooling apparatus includes: a refrigerant
passage (205) connected to liquid side communication pipes (21, 22)
of the refrigerating apparatus (10); a cooling fluid circuit (220)
in which cooling fluid flows; a subcooling heat exchanger (210) for
cooling the heat source side refrigerant in the refrigerant passage
(205) by heat exchange with the cooling fluid; and control means
(240) for controlling a flowing state of the cooling fluid in the
cooling fluid circuit (220) according to a flowing state of the
heat source side refrigerant in the refrigerant passage (205).
[0009] In the first invention, the refrigerant passes to and fro
between the heat source unit (11) and the utility unit (12, 13, 14)
through communication pipes in the refrigerating apparatus (10) to
which the subcooling apparatus (200) is incorporated. The
refrigerant passage (205) of the subcooling apparatus (200) is
connected to the liquid side communication pipes (21, 22) of the
refrigerating apparatus (10) so that the heat source side
refrigerant of the refrigerating apparatus (10) flows therethrough.
The cooling fluid flows in the cooling fluid circuit (220) of the
subcooling apparatus (200). In the subcooling heat exchanger (210),
the heat source side refrigerant flowing in the refrigerant passage
(205) is cooled by heat exchange with the cooling fluid.
[0010] The subcooling apparatus (200) in this invention assists the
operation of the refrigerating apparatus (10). Accordingly,
operation of the subcooling apparatus (200) is required only during
operation of the refrigerating apparatus (10), and therefore, the
operation of only the subcooling apparatus (200) in non-operation
of the refrigerating apparatus (10) is nonsense. Also, the
subcooling apparatus (200) of this invention is provided for
increasing the cooling power at the utility unit (12, 13, 14).
Therefore, in the condition, for example, that the refrigerating
apparatus (10) serves as a heat pump, no or less effect is expected
through the operation of the subcooling apparatus (200). Thus, the
state that the subcooling apparatus (200) should be operated or
should not be operated depends on the operation of the
refrigerating apparatus (10).
[0011] In contrast, in the subcooling apparatus (200) of this
invention, the control means (240) controls the flowing state of
the cooling fluid in the cooling fluid circuit (220). The control
means (240) performs control of the flowing state of the cooling
fluid according to the flowing state of the heat source side
refrigerant in the refrigerant circuit (205). In the refrigerant
passage (205), the heat source side refrigerant passing to and fro
between the heat source unit (11) and the utility unit (12, 13, 14)
through the liquid side communication pipes (21, 22) flows.
Accordingly, the operation state of the refrigerating apparatus
(10) can be judged on the basis of the flowing state of the
refrigerant in the refrigerant passage (205). Therefore, the
control means (240) of the subcooling apparatus (200) controls the
flowing state of the cooling fluid in the cooling fluid circuit
(220) according to the flowing state of the heat source side
refrigerant in the refrigerant passage (205) without receiving a
signal relating to the operation state of the refrigerating
apparatus (10) from the refrigerating apparatus (10).
[0012] Referring to the second invention, in the subcooling
apparatus of the first invention, the cooling fluid circuit is
composed of a subcooling refrigerant circuit (220), and the
subcooling refrigerant circuit (220) includes a subcooling
compressor (221) and performs a refrigeration cycle by circulating
subcooling refrigerant as the cooling fluid.
[0013] In the second invention, the refrigeration cycle is
performed by circulating the subcooling refrigerant in the
subcooling refrigerant circuit (220) of the subcooling apparatus
(200). The subcooling heat exchanger (210) performs heat exchange
between the heat source side refrigerant flowing in the refrigerant
passage (205) and the subcooling refrigerant. In the subcooling
heat exchanger (210), the subcooling refrigerant absorbs heat from
the heat source side refrigerant to be evaporated, thereby cooling
the heat source side refrigerant.
[0014] Referring to the third invention, in the subcooling
apparatus of the second invention, the control means (240) controls
a circulation state of the subcooling refrigerant in the subcooling
refrigerant circuit (220) by controlling operation of the
subcooling compressor (221).
[0015] In the third invention, when the control means (240) adjusts
operation capacity of the subcooling compressor (221), the
circulation amount of the subcooling refrigerant in the subcooling
refrigerant circuit (220) varies. Therefore, control of the
operation of the subcooling compressor (221) attains control of the
circulation state of the subcooling refrigerant in the subcooling
refrigerant circuit (220).
[0016] Referring to the fourth invention, in the subcooling
apparatus of the third invention, the control means (240) detects a
direction in which the heat source side refrigerant flows in the
refrigerant passage (205) and a state in which the heat source side
refrigerant flows or does not flow in refrigerant passage (205) in
operation of the subcooling compressor (221) as the flowing state
of the heat source side refrigerant, and the control means (240)
allows the subcooling compressor (221) to continue operating in a
state that the heat source side refrigerant flows from the heat
source unit (11) towards the utility unit (12, 13, 14) in the
refrigerant passage (205) or stops the operation of the subcooling
compressor (221) in a state that the heat source side refrigerant
flows from the utility unit (12, 13, 14) towards the heat source
unit (11) in the refrigerant passage (205) or in a state that the
heat source side refrigerant does not flow in the refrigerant
passage (205).
[0017] In the fourth invention, the control means (240) detects the
flowing state of the refrigerant in operation of the subcooling
compressor (221). Specifically, the control means (240) detects, as
the flowing state of the refrigerant, the flowing direction of the
refrigerant in the refrigerant passage (205) and flow of the
refrigerant in the refrigerant passage (205).
[0018] The control means (240) of this invention performs operation
control of the subcooling compressor (221) on the basis of the
detected flowing state of the refrigerant. The state that the
refrigerant flows from the heat source unit (11) towards the
utility unit (12, 13, 14) in the refrigerant passage (205) can be
judged as the state that the refrigerating apparatus (10) performs
operation for cooling an object in the utility unit (12, 13, 14).
Therefore, in this state, the control means (240) allows the
subcooling compressor (221) to continue operating so that the
subcooling apparatus (200) cools the refrigerant flowing from the
heat source unit (11) to the utility unit (12, 13, 14). In
contrast, the state that the refrigerant flows from the utility
unit (12, 13, 14) towards the heat source unit (11) in the
refrigerant passage (205) and the state that the refrigerant does
not flow in the refrigerant passage (205) can be judged as the
state that the refrigerating apparatus (10) does not perform the
operation for cooling an object in the utility unit (12, 13, 14).
Therefore, in these states, the control means (240) stops the
operation of the subcooling compressor (221) to avoid unnecessary
operation of the subcooling apparatus (200).
[0019] Referring to the fifth invention, in the subcooling
apparatus of fourth invention, the control means (240) activates
the subcooling compressor (221) after a predetermined time period
elapses from a time point when the subcooling compressor (221) is
stopped.
[0020] In the fifth invention, the control means (240) times
elapsed time from the time point when the subcooling compressor
(221) is stopped. The control means (240) activates the subcooling
compressor (21) upon elapse of the predetermined time period from
the time point when the subcooling compressor (221) is stopped. The
control means (240) detects the flowing state of the refrigerant in
the refrigerant passage (205) after activation of the subcooling
compressor (221) to judge whether the subcooling compressor (221)
should be kept operating or should be stopped.
[0021] Referring to the sixth invention, the subcooling apparatus
of any one of the third, fourth, and fifth inventions further
includes refrigerant temperature detection means (236) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210), wherein the control
means (240) judges the flowing state of the heat source side
refrigerant on the basis of variation in detection value of the
refrigerant temperature detection means (236) from a time point
when the subcooling compressor (221) is activated.
[0022] In the sixth invention, the subcooling apparatus (200)
includes the refrigerant temperature detection means (236). The
refrigerant temperature detection means (236) detects refrigerant
temperature at a part of the refrigerant passage (205) nearer the
utility unit (12, 13, 14) than the subcooling heat exchanger
(210).
[0023] The control means (240) of this invention judges the flowing
state of the refrigerant in the refrigerant passage (205) on the
basis of variation in detection value of the refrigerant
temperature detection means (236) from the time point when the
subcooling compressor (221) is activated. For example, the state
that the detection value of the refrigerant temperature detection
means (236) decreases as the time elapses from activation of the
subcooling compressor (221) can be judges as the state that the
temperature of the refrigerant cooled in the subcooling heat
exchanger (210) is detected by the refrigerant temperature
detection means (236), and in turn, can be judged as the state that
the refrigerant flows from the heat source unit (11) towards the
utility unit (12, 13, 14) in the refrigerant passage (205). Also,
the state that the detection value of the refrigerant temperature
detection means (236) does not vary even after a predetermined time
period elapses from activation of the subcooling compressor (221)
can be judges as the state that the temperature of the refrigerant
before flowing into the subcooling heat exchanger (210) is detected
by the refrigerant temperature detection means (236) or as the
state that the refrigerant does not flow in the refrigerant passage
(205).
[0024] Referring to the seventh invention, the subcooling apparatus
of any one of the third, fourth, and fifth inventions further
includes: refrigerant temperature detection means (236) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210); and evaporation
temperature detection means (234) for detecting evaporation
temperature of the subcooling refrigerant in the subcooling heat
exchanger (210), wherein the control means (240) judges the flowing
state of the heat source side refrigerant on the basis of a
detection value of the refrigerant temperature detection means
(236) and a detection value of the evaporation temperature
detection means (234).
[0025] In the seventh invention, the subcooling apparatus (200)
includes the refrigerant temperature detection means (236) and the
evaporation temperature detection means (234). The refrigerant
temperature detection means (236) detects refrigerant temperature
at a part of the refrigerant passage (205) nearer the utility unit
(12, 13, 14) than the subcooling heat exchanger (210). The
evaporation temperature detection means (234) detects evaporation
temperature of the subcooling refrigerant in the subcooling heat
exchanger (210).
[0026] The control means (240) of this invention judges the flowing
state of the refrigerant in the refrigerant passage (205) on the
basis of the detection value of the refrigerant temperature
detection means (236) and the detection value of the evaporation
temperature detection means (234). For example, the state that the
detection value of the refrigerant temperature detection means
(236) is slightly greater than the detection value of the
evaporation temperature detection means (234) can be judged as the
state that the temperature of the refrigerant cooled in the
subcooling heat exchanger (210) is detected by the refrigerant
temperature detection means (236), and in turn, can be judged as
the state that the refrigerant flows from the heat source unit (11)
towards the utility unit (12, 13, 14) in the refrigerant passage
(205). In contrast, the state that the detection value of the
refrigerant temperature detection means (236) is largely greater
than the detection value of the evaporation temperature detection
means (234) can be judged as the state that the temperature of the
refrigerant before flowing into the subcooling heat exchanger (210)
is detected by the refrigerant temperature detection means (236) or
as the state that the refrigerant does not flow in the refrigerant
passage (205).
[0027] Referring to the eighth invention, the subcooling apparatus
of any one of the third, fourth, and fifth inventions further
includes: first refrigerant temperature detection means (237) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210); and second
refrigerant temperature detection means (238) for detecting
temperature of the heat source side refrigerant at a part of the
refrigerant passage (205) nearer the heat source unit (11) than the
subcooling heat exchanger (210), wherein the control means (240)
judges the flowing state of the heat source side refrigerant on the
basis of a detection value of the first refrigerant temperature
detection means (237) and a detection value of the second
refrigerant temperature detection means (238).
[0028] In the eighth invention, the subcooling apparatus (200)
includes the first refrigerant temperature detection means (237)
and the second refrigerant temperature detection means (238). The
first refrigerant temperature detection means (237) detects the
refrigerant temperature at a part of the refrigerant passage (205)
nearer the utility unit (12, 13, 14) than the subcooling heat
exchanger (210). The second refrigerant temperature detection means
(238) detects refrigerant temperature at a part of the refrigerant
passage (205) nearer the heat source unit (11) than the subcooling
heat exchanger (210).
[0029] The control means (240) of this invention judges the flowing
state of the refrigerant in the refrigerant passage (205) on the
basis of the detection value of the first refrigerant temperature
detection means (237) and the detection value of the second
refrigerant temperature detection means (238). For example, the
state that the detection value of the first refrigerant temperature
detection means (237) is sufficiently smaller than the detection
value of the second refrigerant temperature detection means (238)
can be judged as the state that the refrigerant flowing from the
heat source unit (11) towards the utility unit (12, 13, 14) is
cooled in the subcooling heat exchanger (210). In revere, the state
that the detection value of the first refrigerant temperature
detection means (237) is greater than the detection value of the
second refrigerant temperature detection means (238) can be judged
as the state that the refrigerant flowing from the utility unit
(12, 13, 14) towards the heat source unit (11) is cooled in the
subcooling heat exchanger (210). As well, the state that the
detection value of the first refrigerant temperature detection
means (237) is almost equal to the detection value of the second
refrigerant temperature detection means (238) can be judged as the
state that the refrigerant does not flow in the refrigerant passage
(205).
[0030] Referring to the ninth invention, in the subcooling
apparatus of any one of the first, second, and third invention, a
flow meter (251) is provided at the refrigerant passage (205) for
detecting a flow rate of the heat source side refrigerant, and the
control means (240) uses a detection value of the flow meter (251)
as a flowing state indication vale that indicates the flowing state
of the heat source side refrigerant, and the control means (240)
determines, on the basis of the flowing state indication value,
whether the flow of the cooling fluid should be continued or
stopped in a state that the cooling fluid flows in the cooling
fluid circuit (220).
[0031] In the ninth invention, the detection value of the flow
meter (251) is input to the control means (240). The flowing state
of the heat source side refrigerant in the refrigerant passage
(205) can be judged from the detection value of the flow meter
(251). Therefore, the control means (240) uses the detection value
of the flow meter (251) as a flowing state indication value to
control the flowing state of the cooling fluid in the cooling fluid
circuit (220) on the basis of the flowing state indication
value.
[0032] Referring to the tenth invention, the subcooling apparatus
of any one of the first, second, and third inventions, further
includes: first refrigerant temperature detection means (237) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210); and second
refrigerant temperature detection means (238) for detecting
temperature of the heat source side refrigerant at a part of the
refrigerant passage (205) nearer the heat source unit (11) than the
subcooling heat exchanger (210), wherein the control means (240)
uses a difference between a detection value of the first
refrigerant temperature detection means (237) and a detection value
of the second refrigerant temperature detection means (238) as a
flowing state indication value that indicates the flowing state of
the heat source side refrigerant, and the control means (240)
determines, on the basis of the flowing state indication value,
whether the flow of the cooling fluid should be continued or
stopped in a state that the cooling fluid flows in the cooling
fluid circuit (220).
[0033] In the tenth invention, the detection values of the first
refrigerant temperature detection means (237) and the second
refrigerant temperature detection means (238) are input to the
control means (240). Comparison between the detection value of the
first refrigerant temperature detection means (237) and the
detection value of the second refrigerant temperature detection
means (238) attains judgment of the flowing state of the heat
source side refrigerant in the refrigerant passage (205). For
example, the state that the detection value of the first
refrigerant temperature detection means (237) is smaller than the
detection value of the second refrigerant temperature detection
means (238) can be judged as the state that the heat source side
refrigerant flows from the heat source unit (11) towards the
utility unit (12, 13, 14) in the refrigerant passage (205). The
other states can be judged as the state that the heat source side
refrigerant flows from the utility unit (12, 13, 14) towards the
heat source unit (11) in the refrigerant passage (205) or as the
state that the heat source side refrigerant does not flow therein.
Therefore, the control means (240) uses the difference between the
detection value of the first refrigerant temperature detection
means (237) and the detection value of the second refrigerant
temperature detection means (238) as a flowing state indication
value to control the flowing state of the cooling fluid in the
cooling fluid circuit (220) on the basis of the flowing state
indication value.
[0034] Referring to the eleventh invention, the subcooling
apparatus of any one of the first, second, and third inventions
further includes refrigerant temperature detection means (236) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210), wherein the control
means (240) uses variation in detection value of the refrigerant
temperature detection means (236) as a flowing state indication
value that indicates the flowing state of the heat source side
refrigerant, and the control means (240) determines, on the basis
of the flowing state indication value, whether the flow of the
cooling fluid should be continued or stopped in a state that the
cooling fluid flows in the cooling fluid circuit (220).
[0035] In the eleventh invention, the detection value of the
refrigerant temperature detection means (236) is input to the
control means (240). Monitoring variation in detection value of the
refrigerant temperature detection means (236) attains judgment of
the flowing state of the heat source side refrigerant in the
refrigerant passage (205). For example, the state that the
detection value of the refrigerant temperature detection means
(236) decreases in the state that the cooling fluid flows is judged
as the state that the heat source side refrigerant flows from the
heat source unit (11) towards the utility unit (12, 13, 14) in the
refrigerant passage (205). The other states can be judges as the
state that the heat source side refrigerant flows from the utility
unit (12, 13, 14) towards the heat source unit (11) in the
refrigerant passage (205) or as the state that the heat source side
refrigerant does not flow therein. Therefore, the control means
(240) uses the detection value of the refrigerant temperature
detection means (236) as a flowing state indication value to
control the flowing state of the cooling fluid in the cooling fluid
circuit (220) on the basis of the flowing state indication
value.
[0036] Referring to the twelfth invention, in the subcooling
apparatus of any one of the first, second, and third inventions,
the cooling fluid circuit (220) includes inlet side fluid
temperature detection means (252) for detecting temperature of the
cooling fluid at an inlet of the subcooling heat exchanger (210)
and outlet side fluid temperature detection means (253) for
detecting temperature of the cooling fluid at an outlet of the
subcooling heat exchanger (210), and the control means (240) uses a
difference between a detection value of the inlet side fluid
temperature detection means (252) and a detection value of the
outlet side fluid temperature detection means (253) as a flowing
state indication value that indicates the flowing state of the heat
source side refrigerant, and the control means (240) determines, on
the basis of the flowing state indication value, whether the flow
of the cooling fluid should be continued or stopped in a state that
the cooling fluid flows in the cooling fluid circuit (220).
[0037] In the twelfth invention, the detection values of the inlet
side fluid temperature detection means (252) and the outlet side
fluid temperature detection means (253) are input to the control
means (240). Comparison between the detection value of the inlet
side fluid temperature detection means (252) and the detection
value of the inlet side fluid temperature detection means (252)
attains judgment of the flowing state of the heat source side
refrigerant in the refrigerant passage (205). For example, the
state that the detection value of the inlet side fluid temperature
detection means (252) is greater than the detection value of the
inlet side fluid temperature detection means (252) is judged as the
state that the heat source side refrigerant flows from the heat
source unit (11) towards the utility unit (12, 13, 14) in the
refrigerant passage (205). The other states can be judges as the
state that the heat source side refrigerant flows from the utility
unit (12, 13, 14) towards the heat source unit (11) in the
refrigerant passage (205) or as the state that the heat source side
refrigerant does not flow therein. Therefore, the control means
(240) uses the difference between the detection value of the inlet
side fluid temperature detection means (252) and the detection
value of the outlet side fluid temperature detection means (253) as
a flowing state indication value to control the flowing state of
the cooling fluid in the cooling fluid circuit (220) on the basis
of the flowing state indication value.
[0038] Referring to the thirteenth invention, in the subcooling
apparatus of the second or third invention, the subcooling
refrigerant circuit (220) includes evaporation pressure detection
means (234) for detecting evaporation pressure of the subcooling
refrigerant in the subcooling heat exchanger (210), and the control
means (240) uses a detection value of the evaporation pressure
detection means (234) as a flowing state indication value that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether circulation of the subcooling fluid
should be continued or stopped in a state that the subcooling fluid
circulates in the cooling fluid circuit (220).
[0039] In the thirteenth invention, the detection value of the
evaporation pressure detection means (234) is input to the control
means (240). Monitoring variation in detection value of the
evaporation pressure detection means (234) attains judgment of the
flowing state of the heat source side refrigerant in the
refrigerant passage (205). For example, the state that the
detection value of the evaporation pressure detection means (234)
is greater to some extent than a predetermined value in the state
that the subcooling refrigerant circulates is judged as the state
that the heat source side refrigerant flows in the refrigerant
passage (205). The other states can be judged as the state that the
heat source side refrigerant does not flow in the refrigerant
passage (205). Therefore, the control means (240) uses the
detection value of the evaporation pressure detection means (234)
as a flowing state indication value to control the flowing state of
the subcooling refrigerant in the subcooling refrigerant circuit
(220) on the basis of the flowing state indication value.
[0040] Referring to the fourteenth invention, the subcooling
apparatus of the second or third invention further includes:
refrigerant temperature detection means (236) for detecting
temperature of the heat source side refrigerant at a part of the
refrigerant passage (205) nearer the utility unit (12, 13, 14) than
the subcooling heat exchanger (210); and evaporation temperature
detection means (234) for detecting evaporation temperature of the
subcooling refrigerant in the subcooling heat exchanger (210),
wherein the control means (240) uses a difference between a
detection value of the refrigerant temperature detection means
(236) and a detection value of the evaporation temperature
detection means (234) as a flowing state indication value that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether circulation of the subcooling
refrigerant should be continued or stopped in a state that the
subcooling refrigerant circulates in the subcooling refrigerant
circuit (220).
[0041] In the fourteenth invention, the detection values of the
refrigerant temperature detection means (236) and the evaporation
temperature detection means (234) are input to the control means
(240). Comparison between the detection value of the refrigerant
temperature detection means (236) and the detection value of the
evaporation temperature detection means (234) attains judgment of
the flowing state of the heat source side refrigerant in the
refrigerant passage (205). For example, the state that the
difference between the detection value of the refrigerant
temperature detection means (236) and the detection value of the
evaporation temperature detection means (234) is equal to or
smaller than a predetermined value (10.degree. C., for example) can
be judged as the state that the heat source side refrigerant flows
from the heat source unit (11) towards the utility unit (12, 13,
14) in the refrigerant passage (205). The other states can be
judged as the state that the heat source side refrigerant flows
from the utility unit (12, 13, 14) towards the heat source unit
(11) in the refrigerant passage (205) or as the state that the heat
source side refrigerant does not flow therein. Therefore, the
control means (240) uses the difference between the detection value
of the refrigerant temperature detection means (236) and the
detection value of the evaporation temperature detection means
(234) as a flowing state indication value to control the flowing
state of the subcooling refrigerant in the subcooling refrigerant
circuit (220) on the basis of the flowing state indication
value.
[0042] Referring to the fifteenth invention, the subcooling
apparatus of any one of the first, second, and third inventions,
further includes refrigerant temperature detection means (236) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210), wherein the control
means (240) uses a detection value of the refrigerant temperature
detection means (236) as a flowing state indication value that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether the flow of the cooling fluid
should be started or kept stopping in a state that the cooling
fluid stops flowing in the cooling fluid circuit (220).
[0043] In the fifteenth invention, the detection value of the
refrigerant temperature detection means (236) is input to the
control means (240). Monitoring the detection value of the
refrigerant temperature detection means (236) attains judgment of
the flowing state of the heat source side refrigerant in the
refrigerant passage (205). For example, the state that the
detection value of the refrigerant temperature detection means
(236) is greater to some extent than a predetermined value in the
state that the cooling fluid stops flowing can be judged as the
state that the heat source side refrigerant flows from the heat
source unit (11) towards the utility unit (12, 13, 14) in the
refrigerant passage (205). The other states can be judged as the
state that the heat source side refrigerant flows from the utility
unit (12, 13, 14) towards the heat source unit (11) in the
refrigerant passage (205) or as the state that the heat source side
refrigerant does not flow therein. Therefore, the control means
(240) uses the detection value of the refrigerant temperature
detection means (236) as a flowing state indication value to
control the flowing state of the cooling fluid in the cooling fluid
circuit (220) on the basis of the flowing state indication
value.
[0044] Referring to the sixteenth invention, the subcooling
apparatus of any one of the first, second, and third inventions
further includes refrigerant temperature detection means (236) for
detecting temperature of the heat source side refrigerant at a part
of the refrigerant passage (205) nearer the utility unit (12, 13,
14) than the subcooling heat exchanger (210), wherein the control
means (240) uses variation in detection value of the refrigerant
temperature detection means (236) as a flowing state indication
value that indicates the flowing state of the heat source side
refrigerant, and the control means (240) determines, on the basis
of the flowing state indication value, whether the flow of the
cooling fluid should be started or kept stopping in a state that
the cooling fluid stops flowing in the cooling fluid circuit
(220).
[0045] In the sixteenth invention, the detection value of the
refrigerant temperature detection means (236) is input to the
control means (240). Monitoring variation in detection value of the
refrigerant temperature detection means (236) attains judgment of
the flowing state of the heat source side refrigerant in the
refrigerant passage (205). For example, the state that the
detection value of the refrigerant temperature detection means
(236) increases in the state that the cooling fluid stops flowing
can be judged as the state that the heat source side refrigerant
flows from the heat source unit (11) towards the utility unit (12,
13, 14) in the refrigerant passage (205). The other states can be
judged as the state that the heat source side refrigerant flows
from the utility unit (12, 13, 14) towards the heat source unit
(11) in the refrigerant passage (205) or as the state that the heat
source side refrigerant does not flow therein. Therefore, the
control means (240) uses the variation in detection value of the
refrigerant temperature detection means (236) as a flowing state
indication value to control the flowing state of the cooling fluid
in the cooling fluid circuit (220) on the basis of the flowing
state indication value.
[0046] Referring to the seventeenth invention, the subcooling
apparatus of the second or third invention further includes:
outside air temperature detection means (231) for detecting
temperature of outside air; and refrigerant temperature detection
means (236) for detecting temperature of the heat source side
refrigerant at a part of the refrigerant passage (205) nearer the
utility unit (12, 13, 14) than the subcooling heat exchanger (210),
wherein the control means (240) uses a difference between a
detection value of the refrigerant temperature detection means
(236) and a detection value of the outside air temperature
detection means (231) as a flowing state indication value that
indicates the flowing state of the heat source side refrigerant,
and the control means (240) determines, on the basis of the flowing
state indication value, whether the flow of the subcooling
refrigerant should be started or kept stopping in a state that the
subcooling refrigerant stops flowing in the subcooling refrigerant
circuit (220).
[0047] In the seventeenth invention, the detection values of the
outside air temperature detection means (231) and the refrigerant
temperature detection means (236) are input to the control means
(240). Comparison between the detection value of the refrigerant
temperature detection means (236) and the detection value of the
outside air temperature detection means (231) attains judgment of
the flowing state of the heat source side refrigerant in the
refrigerant passage (205). For example, the state that the
difference between the detection value of the refrigerant
temperature detection means (236) and the detection value of the
outside air temperature detection means (231) is equal to or
greater than a predetermined value in the state that the cooling
fluid stops flowing can be judged as the state that the heat source
side refrigerant flows in the refrigerant passage (205). The
reverse state can be judged as the state that the heat source side
refrigerant does not flow therein. Therefore, the control means
(240) uses the difference between the detection value of the
refrigerant temperature detection means (236) and the detection
value of the outside air temperature detection means (231) as a
flowing state indication value to control the flowing state of the
subcooling refrigerant in the subcooling refrigerant circuit (220)
on the basis of the flowing state indication value.
[0048] The eighteenth invention directs to a subcooling apparatus
which is incorporated to a refrigerating apparatus (10) that
performs a refrigeration cycle by circulating heat source side
refrigerant between a heat source unit (11) and a utility unit (12,
13, 14) connected to each other by means of communication pipes and
which cools the heat source side refrigerant in the refrigerating
apparatus (10) sent from the heat source unit (11) to the utility
unit (12, 13, 14). Wherein the heat source unit (11) of the
refrigerating apparatus (10) performs heat exchange between the
heat source side refrigerant and outdoor air, and the subcooling
apparatus includes: a refrigerant passage (205) connected to liquid
side communication pipes (21, 22) of the refrigerating apparatus
(10); a cooling fluid circuit (220) in which cooling fluid flows; a
subcooling heat exchanger (210) for cooling the heat source side
refrigerant in the refrigerant passage (205) by heat exchange with
the cooling fluid; outside air temperature detection means (231)
for detecting temperature of outside air; and control means (240)
for controlling a flowing state of the cooling fluid in the cooling
fluid circuit (220) according to a detection value of the outside
air temperature detection means (231).
[0049] In the eighteenth invention, similar to the first invention,
the cooling fluid cools the heat source side refrigerant in the
refrigerant passage (205). The detection value of the outside air
temperature detection means (231) is input to the control means
(240) of this invention. Monitoring the detection value of the
outside air temperature detection means (231) attains estimation of
the magnitude of cooling load in the utility unit (12, 13, 14),
leading to judgment as to whether or not the heat source side
refrigerant in the refrigerant passage (205) should be cooled.
Therefore, the control means (240) controls the flowing state of
the cooling fluid in the cooling fluid circuit (220) on the basis
of the detection value of the outside air temperature detection
means (231).
[0050] Referring to the nineteenth invention, in the subcooling
apparatus of the eighteenth invention, the cooling fluid circuit is
composed of a subcooling refrigerant circuit (220), and the
subcooling refrigerant circuit (220) includes a subcooling
compressor (221) and performs a refrigeration cycle by circulating
the subcooling refrigerant as the cooling fluid.
[0051] In the nineteenth invention, the subcooling refrigerant
circuit (220) of the subcooling apparatus (200) performs the
refrigeration cycle by circulating the subcooling refrigerant. The
subcooling heat exchanger (210) performs heat exchange between the
heat source side refrigerant flowing in the refrigerant passage
(205) and the subcooling refrigerant. In the subcooling heat
exchanger (210), the subcooling refrigerant absorbs heat from the
heat source side refrigerant to be evaporated, thereby cooling the
heat source side refrigerant.
[0052] Referring to the twentieth invention, in the subcooling
apparatus of the eighteenth or nineteenth invention, the control
means (240) determines, on the basis of a detection value of the
outside air temperature detection means (231), whether the flow of
the cooling fluid should be continued or stopped in a state that
the cooling fluid flows in the cooling fluid circuit (220).
[0053] Referring to the twenty-first invention, in the subcooling
apparatus of the eighteenth or nineteenth invention, the control
means (240) determines, on the basis of a detection value of the
outside air temperature detection means (231), whether the flow of
the cooling fluid should be started or kept stopping in a state
that the cooling fluid does not flow in the cooling fluid circuit
(220).
[0054] In the twentieth and twenty-first inventions, the control
means (240) monitors the detection value of the outside air
temperature detection means (231). The detection value of the
outside air temperature detection means (231) exceeding a
predetermined reference value (25.degree. C., for example) leads to
estimation of the state that the cooling load in the utility unit
(12, 13, 14) increases and the heat source side refrigerant in the
refrigerant passage (205) should be cooled. The reverse state leads
to estimation of the state that the cooling load in the utility
unit (12, 13, 14) is not so high and cooling of the heat source
side refrigerant in the refrigerant passage (205) is not so
necessary. Therefore, the control means (240) judges on the basis
of the detection value of the outside air temperature detection
means (231) whether or not the cooling fluid should be allowed to
flow in the cooling fluid circuit (220).
[0055] Referring to the twenty-second invention, the subcooling
apparatus of the second or nineteenth invention further includes:
heat radiation heat exchanger (222) connected to the subcooling
refrigerant circuit (220) for performing heat exchange between the
subcooling refrigerant and outdoor air; and outdoor fan (230) for
supplying outdoor air to the heat radiation heat exchanger (222),
wherein the subcooling refrigerant circuit (220) is capable of
performing natural circulation operation that allows the subcooling
refrigerant to naturally circulate by operating the outdoor fan
(230) in non-operation of the subcooling compressor (221), and the
control means (240) allows the subcooling refrigerant circuit (220)
to perform the natural circulation operation by activating the
outdoor fan (230) in order to start circulation of the subcooling
refrigerant, and the control means (240) determines whether the
subcooling compressor (221) should be activated or kept stopping
according to the flowing state of the heat source side refrigerant
in the refrigerant passage (205) in natural circulation
operation.
[0056] In the twenty-second invention, even during the time when
the subcooling compressor (221) is stopped, the subcooling
refrigerant circulates in the subcooling refrigerant circuit (220)
by operating the outdoor fan (230). Namely, in the subcooling
refrigerant circuit (220), the operation of the outdoor fan (230)
only can cool the heat source side refrigerant in the subcooling
heat exchanger (210). For starting the circulation of the
subcooling refrigerant, the control means (240) of this invention
first activates only the outdoor fan (230) to cause natural
circulation of the subcooling refrigerant in the subcooling
refrigerant circuit (220) for cooling the heat source side
refrigerant through the naturally circulating subcooling
refrigerant. Then, the control means (240) judges whether or not
the heat source side refrigerant is sufficiently cooled in this
condition and determines whether the subcooling compressor (221)
should be activated according to the judgment. In detail, the
control means (240) keeps the subcooling compressor (221) being
stopped when the heat source side refrigerant is sufficiently
cooled while activating the subcooling compressor (221) when the
heat source side refrigerant is insufficiently cooled for starting
the refrigeration cycle in the subcooling refrigerant circuit
(220).
EFFECTS OF THE INVENTION
[0057] In the subcooling apparatus (200) of the present invention,
the control means (240) controls the operation of the subcooling
compressor (221) according to the flowing state of the refrigerant
in the refrigerant passage (205). Accordingly, in the subcooling
apparatus (200), the operation of the subcooling compressor (221)
can be controlled according to the operation state of the
refrigerating apparatus (10) without sending and receiving a signal
to and from the refrigerating apparatus (10). As a result, for
incorporating the subcooling apparatus (200) to the refrigerating
apparatus (10), only connection of the refrigerant passage (205) of
the subcooling apparatus (220) to the liquid side communication
pipes (21, 22) of the refrigerating apparatus (10) is required.
This eliminates the need to wire any communication wirings for
sending and receiving a signal between the refrigerating apparatus
(10) and the subcooling apparatus (200).
[0058] Hence, according to the present invention, the number of
operation steps for incorporating the subcooling apparatus (200) to
the refrigerating apparatus (10) can be reduced and troubles caused
due to human errors in installation, such as mis-wiring and the
like, can be obviated.
BRIEF DESCRIPTION OF THE DRAWINGS
[0059] FIG. 1 is a piped system diagram showing a construction of a
refrigeration system including a subcooling unit.
[0060] FIG. 2 is a piped system diagram showing operation in
cooling operation of the refrigeration system.
[0061] FIG. 3 is a piped system diagram showing operation in first
heating operation of the refrigeration system.
[0062] FIG. 4 is a piped system diagram showing another operation
in the first heating operation of the refrigeration system.
[0063] FIG. 5 is a piped system diagram showing operation of second
heating operation of the refrigeration system.
[0064] FIG. 6 is a flowchart showing control operation by a
controller in the subcooling unit.
[0065] FIG. 7 is a piped system diagram showing a construction of a
refrigeration system in Modified Example 1 of Embodiment.
[0066] FIG. 8 is a piped system diagram showing a construction of a
refrigeration system in Modified Example 2 of Embodiment.
[0067] FIG. 9 is a piped system diagram showing a construction of a
refrigeration system in Modified Example 5 of Embodiment.
[0068] FIG. 10 a piped system diagram showing a construction of a
refrigeration system in Modified Example 10 of Embodiment.
EXPLANATION OF REFERENCE NUMERALS
[0069] 10 refrigerating apparatus
[0070] 11 outdoor unit (heat source unit)
[0071] 12 air conditioning unit (utility unit)
[0072] 13 cooling showcase (utility unit)
[0073] 14 refrigeration showcase (utility unit)
[0074] 21 first liquid side communication pipe (liquid side
communication pipe)
[0075] 22 second liquid side communication pipe (liquid side
communication pipe)
[0076] 205 refrigerant passage
[0077] 210 subcooling heat exchanger
[0078] 220 subcooling refrigerant circuit (cooling fluid
circuit)
[0079] 221 subcooling compressor
[0080] 200 subcooling unit (subcooling apparatus)
[0081] 230 outdoor fan
[0082] 234 suction pressure sensor (evaporation temperature
detection means, evaporation pressure detection means)
[0083] 236 refrigerant temperature sensor (refrigerant temperature
detection means)
[0084] 237 first refrigerant temperature sensor (first refrigerant
temperature detection means)
[0085] 238 second refrigerant temperature sensor (second
refrigerant temperature detection means)
[0086] 240 controller (control means)
[0087] 251 flow meter
[0088] 252 first subcooling refrigerant temperature sensor (inlet
side fluid temperature detection means)
[0089] 253 second subcooling refrigerant temperature sensor (outlet
side fluid temperature detection means)
BEST MODE FOR CARRYING OUT THE INVENTION
[0090] Embodiments of the present invention will be described in
detail with reference to the drawings.
[0091] A refrigeration system in the present embodiment is
installed in a convenience store or the like for conditioning air
in the store and cooling showcases. The refrigeration system
includes a subcooling unit (200) as a subcooling apparatus
according to the present invention and a refrigerating apparatus
(10) to which the subcooling unit (200) is incorporated.
[0092] As shown in FIG. 1, the refrigeration system includes an
outdoor unit (11), an air conditioning unit (12), a cooling
showcase (13), a refrigeration showcase (14), a booster unit (15),
and the subcooling unit (200). The refrigerating apparatus (10) is
composed of the outdoor unit (11), the air conditioning unit (12),
the cooling showcase (13), the refrigeration showcase (14), and the
booster unit (15). In the refrigeration system, the outdoor unit
(11) and the subcooling unit (200) are installed outdoors while the
other units such as the air conditioning unit (12) and the like are
installed in a store such as a convenience store.
[0093] The outdoor unit (11) includes an outdoor circuit (40), the
air conditioning unit (12) includes an air conditioning circuit
(100), the cooling showcase (13) includes a cooling circuit (110),
the refrigeration showcase (14) includes a refrigeration circuit
(130), and the booster unit (15) includes a booster circuit (140).
Further, the subcooling unit (20) includes a refrigerant passage
(205). In the refrigeration system, these circuits (40, 100, . . .
) are connected to the refrigerant passage (205) of the subcooling
unit (200) by means of pipes to form a refrigerant circuit (20).
Heat source side refrigerant is filled in the refrigerant circuit
(20).
[0094] A first liquid side communication pipe (21), a second liquid
side communication pipe (22), a first gas side communication pipe
(23), and a second gas side communication pipe (24) are provided in
the refrigerant circuit (20).
[0095] The first liquid side communication pipe (21) connects one
end of the refrigerant passage (205) of the subcooling unit (200)
and the outdoor circuit (40). One end of the second liquid side
communication pipe (22) is connected to the other end of the
refrigerant passage (205). The other end of the second liquid side
communication pipe (22) branches into three ends to be connected to
the air conditioning circuit (100), the cooling circuit (100), and
the refrigeration circuit (130). A liquid side closing valve (25)
is provided in one of branch pipes of the second liquid side
communication pipe (22) which is connected to the refrigeration
circuit (130).
[0096] One end of the first gas side communication pipe (23)
branches into two ends connected to the cooling circuit (110) and
the booster circuit (140). A gas side closing valve (26) is
provided in one of the branch pipes of the first gas side
communication pipe (23) which is connected to the booster circuit
(140). The other end of the first gas side communication pipe (23)
is connected to the outdoor circuit (40). The second gas side
communication pipe (24) connects the air conditioning circuit (100)
and the outdoor circuit (40).
[0097] <Outdoor Unit>
[0098] The outdoor unit (11) serves as a heat source unit of the
refrigerating apparatus (10). The outdoor unit (11) includes the
outdoor circuit (40).
[0099] The outdoor circuit (40) includes a variable capacity
compressor (41), a first fixed capacity compressor (42), a second
fixed capacity compressor (43), an outdoor heat exchanger (44), a
receiver (45), and an outdoor expansion valve (46). The outdoor
circuit (40) also includes three intake pipes (61, 62, 63), two
discharge pipes (64, 65), four liquid pipes (81, 82, 83, 84), and
one high-pressure gas pipe (66). The outdoor circuit (40) further
includes three four-way switching valves (51, 52, 53), one liquid
side closing valve (54), and two gas side closing valves (55,
56).
[0100] In the outdoor circuit (40), the first liquid side
communication pipe (21), the first gas side communication pipe
(23), and the second gas side communication pipe (24) are connected
to the liquid side closing valve (54), the first gas side closing
valve (55), and the second gas side closing valve (56),
respectively.
[0101] Each of the variable capacity compressor (41), the first
fixed capacity compressor (42), and the second fixed capacity
compressor (43) is a hermetic scroll compressor of high-pressure
dome type. Electric power is supplied to the variable capacity
compressor (41) through an inverter. The variable capacity
compressor (41) is variable in capacity by changing the rotation
speed of its compressor motor by changing the output frequency of
the inverter. In contrast, the first and second fixed capacity
compressors (42, 43) are operated by driving their compressor
motors always at a given rotation speed, so that the capacities
thereof are invariable.
[0102] The first suction pipe (61) is connected at one end thereof
to the first gas closing valve (55). The first suction pipe (61)
branches at the other end thereof into a first branch pipe (61a)
and a second branch pipe (61b), wherein the first branch pipe (61a)
is connected to the intake side of the variable capacity compressor
(41) while the second branch pipe (61b) is connected to the third
four-way switching valve (53). A check valve (CV-1) for allowing
the refrigerant to flow from the first gas side closing valve (55)
towards the third four-way switching valve (53) is provided in the
second branch pipe (64b) of the first suction pipe (61).
[0103] The second suction pipe (62) is connected at one end thereof
to the third four-way switching valve (53) and at the other end
thereof to the suction side of the first fixed capacity compressor
(42).
[0104] The third suction pipe (63) is connected at one end thereof
to the second four-way switching valve (52). The third suction pipe
(63) branches at the other end thereof into a first branch pipe
(63a) and a second branch pipe (63b), wherein the first branch pipe
(63a) is connected to the suction side of the second fixed capacity
compressor (43) while the second brand pipe (63b) is connected to
the third four-way switching valve (53). A check valve (CV-2) for
allowing the refrigerant to flow from the second four-way switching
valve (52) towards the third four-way switching valve (53) is
provided in the second branch pipe (63b) of the third suction pipe
(63).
[0105] The first discharge pipe (64) branches at one end thereof
into a first branch pipe (64a) and a second branch pipe (64b),
wherein the first branch pipe (64a) is connected to the discharge
side of the variable capacity compressor (41) while the second
branch pipe (64b) is connected to the discharge side of the first
fixed capacity compressor (42). The other end of the first
discharge pipe (64) is connected to the first four-way switching
valve (51). A check valve (CV-3) for allowing the refrigerant to
flow from the first fixed capacity compressor (42) towards the
first four-way switching valve (51) is provided in the second
branch pipe (64b) of the first discharge pipe (64).
[0106] The second discharge pipe (65) is connected at one end
thereof to the suction side of the second fixed capacity compressor
(43) and at the other end thereof to a part of the discharge pipe
(64) immediately before the first four-way switching valve (51). A
check valve (CV-4) for allowing the refrigerant to flow from the
second fixed capacity compressor (43) towards the first four-way
switching valve (51) is provided in the second discharge pipe
(65).
[0107] The outdoor heat exchanger (44) is a fin and tube heat
exchanger of cross fin type. The outdoor heat exchanger (44)
performs heat exchange between the refrigerant and outdoor air. One
end of the outdoor heat exchanger (44) is connected to the first
four-way switching valve (51) via a closing valve (57). The other
end of the outdoor heat exchanger (44) is connected to the head of
the receiver (45) through the first liquid pipe (81). A check valve
(CV-5) for allowing the refrigerant to flow from the outdoor heat
exchanger (44) towards the receiver (45) is provided in the first
liquid pipe (81).
[0108] To the bottom of the receiver (45), one end of the second
liquid pipe (82) is connected via a closing valve (58). The other
end of the second liquid pipe (82) is connected to the liquid side
closing valve (54). A check valve (CV-6) for allowing the
refrigerant to flow from the receiver (45) towards the liquid side
closing valve (54) is provided in the second liquid pipe (82).
[0109] One end of the third liquid pipe (83) is connected between
the check valve (CV-6) and the liquid side closing valve (54) in
the second liquid pipe (82). The other end of the third liquid pipe
(83) is connected to the head of the receiver through the first
liquid pipe (81). A check valve (CV-7) for allowing the refrigerant
to flow from the one end towards the other end is provided in the
third liquid pipe (83).
[0110] One end of the fourth liquid pipe (84) is connected between
the closing valve (58) and the check valve (CV-6) in the second
liquid pipe (82). The other end of the fourth liquid pipe (84) is
connected between the outdoor heat exchanger (44) and the check
valve (CV-5) in the first liquid pipe (81). A check valve (CV-8)
and the outdoor expansion valve (46) are provided in this order
from the one end towards the other end of the fourth liquid pipe
(84). The check valve (CV-8) is provided for allowing the
refrigerant to flow from the one end towards the other end of the
fourth liquid pipe (84). The outdoor expansion valve (46) is an
electronic expansion valve.
[0111] The high-pressure gas pipe (66) is connected at one end
thereof to a part of the first discharge pipe (64) immediately
before the first four-way switching valve (51). The other end of
the high-pressure gas pipe (66) branches into a first branch pipe
(66a) and a second branch pipe (66b), wherein the first branch pipe
(66a) is connected to the downstream side of the check valve (CV-5)
in the first liquid pipe (81) while the second branch pipe (66b) is
connected to the third four-way switching valve (53). A solenoid
valve (SV-7) and a check valve (CV-9) are provided in the first
branch pipe (66a) of the high-pressure gas pipe (66). The check
valve (CV-9) is arranged on the downstream side of the solenoid
valve (SV-7) for allowing the refrigerant to flow from the solenoid
valve (SV-7) towards the first liquid pipe (81).
[0112] In the first four-way switching valve (51), the first port,
the second port, the third port, and the fourth port are connected
to the terminal end of the first discharge pipe (64), the second
four-way switching valve (52), the outdoor heat exchanger (44), and
the second gas side closing valve (56), respectively. The first
four-way switching valve (51) is exchangeable between the first
state (shown by the solid lines in FIG. 1) that the first port and
the third port communicate with each other while the second port
and the fourth port communicate with each other and the second
state (shown by the broken lines in FIG. 1) that the first port and
the fourth port communicate with each other while the second port
and the third port communicate with each other.
[0113] In the second four-way switching valve (52), the first port,
the second port, and the fourth port are connected to the
downstream side of the check valve (CV-4) in the second discharge
pipe (65), the start end of the second suction pipe (62), and the
second port of the first four-way switching valve (51),
respectively. The third port of the second four-way switching valve
(52) is closed. The second four-way switching valve (52) is
exchangeable between the first state (shown by the solid lines in
FIG. 1) that the first port and the third port communicate with
each other while the second port and the fourth port communicate
with each other and the second state (shown by the broken lines in
FIG. 1) that the first port and the fourth port communicate with
each other while the second port and the third port communicate
with each other.
[0114] In the third four-way switching valve (53), the first port,
the second port, the third port, and the fourth port are connected
to the terminal end of the second branch pipe (66b) of the
high-pressure gas pipe (66), the start end of the second suction
pipe (62), the terminal end of the second branch pipe (61b) of the
first suction pipe (61), and the terminal end of the second branch
pipe (63b) of the third intake pipe (63), respectively. The third
four-way switching valve (53) is exchangeable between the first
state (shown by the solid lines in FIG. 1) that the first port and
the third port communicate with each other while the second port
and the fourth port communicate with each other and the second
state (shown by the broken lines in FIG. 1) that the first port and
the fourth port communicate with each other while the second port
and the third port communicate with each other.
[0115] The outdoor circuit (40) further includes an injection pipe
(85), a communication pipe (87), an oil separator (75), and an oil
return pipe (76). The outdoor circuit (40) also includes four oil
level equalizing pipes (71, 72, 73, 74).
[0116] The injection pipe (85) is provided for liquid injection.
The injection pipe (85) is connected at one end thereof between the
check valve (CV-8) and the outdoor expansion valve (46) in the
fourth liquid pipe (84) and at the other end thereof to the first
suction pipe (61). A closing valve (59) and a flow rate adjusting
valve (86) are provided in this order from the one end towards the
other end of the injection pipe (85). The flow rate adjusting valve
(86) is an electronic expansion valve.
[0117] The communication pipe (87) is connected at one end thereof
between the closing valve (59) and the flow rate adjusting valve
(86) in the injection pipe (85) and at the other end thereof to the
upstream side of the solenoid valve (SV-7) in the first branch pipe
(66a) of the high-pressure gas pipe (66). In the communication pipe
(87), a check valve (CV-10) is provided for allowing the
refrigerant to flow from the one end towards the other end
thereof.
[0118] The oil separator (75) is provided on the upstream side of
the connection point of the first discharge pipe (64) where the
second discharge pipe (65) and the high-pressure gas pipe (66) are
connected to each other. The oil separator (75) is provided for
separating the refrigerator oil from the discharged gas in the
compressors (41, 42).
[0119] The oil return pipe (76) is connected at one end thereof to
the oil separator (75). The oil return pipe (76) branches at the
other end thereof into a first branch pipe (76a) and a second
branch pipe (76b), wherein the first branch pipe (76a) is connected
to the downstream side of the flow rate adjusting valve (86) in the
injection pipe (85) while the second branch pipe (76b) is connected
to the second suction pipe (62). Further, solenoid valves (SV-5,
SV-6) are provided at the first branch pipe (76a) and the second
branch pipe (76b) of the oil return pipe (76), respectively. When
the solenoid valve (SV-5) of the first branch pipe (76a) opens, the
refrigerator oil separated in the oil separator (75) returns to the
first suction pipe (61) through the injection pipe (85). On the
other hand, when the solenoid valve (SV-6) of the second branch
pipe (76b) opens, the refrigerator oil separated in the oil
separator (75) returns to the second suction pipe (62).
[0120] The first oil level equalizing pipe (71) is connected at one
end thereof to the variable capacity compressor (41) and at the
other end thereof to the second suction pipe (62). A solenoid valve
(SV-1) is provided in the first oil level equalizing pipe (71). The
second oil level equalizing pipe (72) is connected at one end
thereof to the first fixed capacity compressor (42) and at the
other end thereof to the first branch pipe (63a) of the third
suction pipe (63). A solenoid valve (SV-2) is provided in the
second oil level equalizing pipe (72). The third oil level
equalizing pipe (73) is connected at one end thereof to the second
fixed capacity compressor (43) and at the other end thereof to the
first branch pipe (61a) of the first suction pipe (61). A solenoid
valve (SV-3) is provided in the third oil level equalizing pipe
(73). The fourth oil level equalizing pipe (74) is connected at one
end thereof to the upstream side of the solenoid valve (SV-2) in
the second oil level equalizing pipe (72) and at the other end
thereof to the first branch pipe (61a) of the first suction pipe
(61). A solenoid valve (SV-4) is provided in the fourth oil level
equalizing pipe (74). Appropriate opening/closing of the solenoid
valves (SV-1 to SV-4) of the oil level equalizing pipes (71 to 74)
equalizes each amount of the refrigerator oil reserved in the
compressors (42, 42, 43).
[0121] A variety of sensors and pressure switches are provided in
the outdoor circuit (40). Specifically, a first suction temperature
sensor (91) and a first suction pressure sensor (92) are provided
in the first suction pipe (61). A second suction pressure sensor
(93) is provided in the second suction pipe (62). A third suction
temperature sensor (94) and a third suction pressure sensor (95)
are provided in the third suction pipe (63). A first discharge
temperature sensor (97) and a first discharge pressure sensor (98)
are provided in the first discharge pipe (64). A high-pressure
switch (69) is provided at each of the branch pipes (64a, 64b) of
the first discharge pipe (64). A second discharge temperate sensor
(99) and a high pressure switch (96) are provided in the second
discharge pipe (65).
[0122] The outdoor unit (11) further includes an outdoor air
temperature sensor (90) and an outdoor fan (48). The outdoor fan
(48) sends outdoor air to the outdoor heat exchanger (44).
[0123] <Air Conditioning Unit>
[0124] The air conditioning unit (12) composes a utility unit. The
air conditioning unit (12) includes the air conditioning circuit
(100). The air conditioning circuit (100) is connected at the
liquid side end thereof to the second liquid side communication
pipe (22) and at the gas side end thereof to the second gas side
communication pipe (24).
[0125] The air conditioning circuit (100) includes an air
conditioning expansion valve (102) and an air conditioning heat
exchanger (101) in this order form the liquid side end towards the
gas side end. The air conditioning heat exchanger (101) is a fin
and tube heat exchanger of cross fin type. The air conditioning
heat exchanger (101) performs heat exchange between the refrigerant
and room air. The air conditioning expansion valve (102) is an
electronic expansion valve.
[0126] The air conditioning unit (12) includes a heat exchanger
temperature sensor (103) and a refrigerant temperature sensor
(104). The heat exchanger temperature sensor (103) is incorporated
at the heat transfer tube of the air conditioning heat exchanger
(101). The refrigerant temperature sensor (104) is incorporated in
the vicinity of the gas side end of the air conditioning circuit
(100). The air conditioning unit (12) also includes an indoor air
temperature sensor (106) and an air conditioning fan (105). The air
conditioning fan (105) sends room air in the store to the air
conditioning heat exchanger (101).
[0127] <Cooling Showcase>
[0128] The Cooling showcase (13) composes the utility unit. The
cooling showcase (13) includes the cooling circuit (110). The
cooling circuit (110) is connected at the liquid side end thereof
to the second liquid side communication pipe (22) and at the gas
side end thereof to the first gas side communication pipe (23).
[0129] The cooling circuit (110) includes a cooling solenoid valve
(114), a cooling expansion valve (112), and a cooling heat
exchanger (111) in this order from the liquid side end towards the
gas side end. The cooling heat exchanger (111) is a fin and tube
heat exchanger of cross fin type. The cooling heat exchanger (111)
performs heat exchange between the refrigerant and the inside air
of the cooling showcase (13). The cooling expansion valve (112) is
a thermostatic expansion valve. The cooling expansion valve (112)
has a temperature sensing bulb (113) incorporated at the pipe on
the outlet side of the cooling heat exchanger (111).
[0130] The cooling showcase (13) includes a cooler temperature
sensor (116) and a cooler fan (115). The cooler fan (115) sends the
inside air of the cooling showcase (13) to the cooling heat
exchanger (111).
[0131] <Refrigeration Showcase>
[0132] The refrigeration showcase (14) composes the utility unit.
The refrigeration showcase (143) includes the refrigeration circuit
(130). The refrigeration circuit (130) is connected at the liquid
side end thereof to the second liquid side communication pipe (22)
and at the gas side end thereof to the booster unit (15) through a
pipe.
[0133] The refrigeration circuit (130) includes a refrigeration
solenoid valve (134), a refrigeration expansion valve (132), and a
refrigeration heat exchanger (131) in this order from the liquid
side end towards the gas side end. The refrigeration heat exchanger
(131) is a fin and tube heat exchanger of cross fin type. The
refrigeration heat exchanger (131) performs heat exchange between
the refrigerant and the inside air of the refrigeration showcase
(14). The refrigeration expansion valve (132) is a thermostatic
expansion valve. The refrigeration expansion valve (132) has a
temperature sensing bulb (133) incorporated at the pipe on the
outlet side of the refrigeration heat exchanger (131).
[0134] The refrigeration showcase (14) includes a refrigerator
temperature sensor (136) and a refrigerator fan (135). The
refrigerator fan (135) sends the inside air of the refrigeration
showcase (14) to the refrigeration heat exchanger (131).
[0135] <Booster Unit>
[0136] The booster unit (15) includes the booster circuit (140).
The booster circuit (140) includes a booster compressor (141), a
suction pipe (143), a discharge pipe (144), and a bypass pipe
(150).
[0137] The booster compressor (141) is a hermetic scroll compressor
of high pressure dome type. Electric power is supplied to the
booster compressor (141) through an inverter. The booster
compressor (141) is variable in capacity by changing the rotation
speed of its compressor motor by changing the output frequency of
the inverter.
[0138] The suction pipe (143) is connected at the terminal end
thereof to the suction side of the booster compressor (141) and at
the start end thereof to the gas side end of the refrigeration
circuit (130) through a pipe.
[0139] The discharge pipe (144) is connected at the start end
thereof to the discharge side of the booster compressor (141) and
at the terminal end thereof to the first gas side communication
pipe (23). The discharge pipe (144) includes a high-pressure switch
(148), an oil separator (145), and a discharge side check valve
(149) in this order from the start end towards the terminal end
thereof. The discharge side check valve (149) allows the
refrigerant to flow from the start end towards the terminal end of
the discharge pipe (144).
[0140] The oil separator (145) is provided for separating the
refrigerator oil from the discharge gas of the booster compressor
(141). One end of an oil return pipe (146) is connected to the oil
separator (145). The other end of the oil return pipe (146) is
connected to the suction pipe (143). The oil return pipe (146)
includes a capillary tube (147). The refrigerator oil separated in
the oil separator (145) is sent back to the suction side of the
booster compressor (141) through the oil return pipe (146).
[0141] The bypass pipe (150) is connected at the start end thereof
to the suction pipe (143) and at the terminal end thereof to a part
of the discharge pipe (64) between the oil separator (145) and the
discharge side check valve (149). The bypass pipe (150) includes a
bypass check valve (151) for allowing the refrigerant to flow from
the start end towards the terminal end thereof.
[0142] <Subcooling Unit>
[0143] The subcooling unit (200) as a subcooling apparatus includes
the refrigerant passage (205), a subcooling refrigerant circuit
(220), a subcooling heat exchanger (210), and a controller
(240).
[0144] The refrigerant passage (205) is connected at one end
thereof to the first liquid side communication pipe (21) and at the
other end thereof to the second liquid side communication pipe
(22).
[0145] The subcooling refrigerant circuit (220) is a closed circuit
formed in such a fashion that the subcooling compressor (221), the
subcooling outdoor heat exchanger (222), a subcooling expansion
valve (223), and the subcooling heat exchanger (210) are connected
by means of pipes in this order. The subcooling refrigerant circuit
(220) serves as a cooling fluid circuit. Subcooling refrigerant
serving as cooling fluid is filled in the subcooling refrigerant
circuit (220). As the subcooling refrigerant, there may be used not
only generally called fluorocarbon refrigerants such as R704 and
the like but also various refrigerants such as carbon dioxide
(CO.sub.2), ammonium, and the like. The subcooling refrigerant
circuit (220) performs a refrigeration cycle by circulating the
subcooling refrigerant filled therein.
[0146] The subcooling compressor (221) is a hermetic scroll
compressor of high pressure dome type. Electric power is supplied
to the subcooling compressor (221) through an inverter. The
subcooling compressor (221) is variable in capacity by changing the
rotation speed of its compressor motor by changing the output
frequency of the inverter. The subcooling outdoor heat exchanger
(222) is a fin and tube heat exchanger of cross fin type. The
subcooling outdoor heat exchanger (222) performs heat exchange
between the subcooling refrigerant and outdoor air. The subcooling
expansion valve (223) is an electronic expansion valve.
[0147] The subcooling heat exchanger (210) is a generally-called a
plate type heat exchanger. A plurality of first flow paths (211)
and a plurality of second flow paths (212) are formed in the
subcooling heat exchanger (210). The first flow paths (211) and the
second flow paths (211) are connected to the subcooling refrigerant
circuit (220) and the refrigerant passage (205), respectively. The
subcooling heat exchanger (210) performs heat exchange between the
subcooling refrigerant flowing in the first flow paths (211) and
the refrigerant of the refrigerating apparatus (10) flowing in the
second flow paths (212).
[0148] The subcooling unit (200) also includes a variety of sensors
and pressure switches. Specifically, in the subcooling refrigerant
circuit (220), a suction temperature sensor (235) and a suction
pressure sensor (234) are provided on the suction side of the
subcooling compressor (221) and a discharge temperature sensor
(233) and a high pressure switch (232) are provided on the
discharge side of the subcooling compressor (221). A refrigerant
temperature sensor (236) is provided at a part of the refrigerant
passage (205) nearer the other end than the subcooling heat
exchanger (210), that is, a part thereof near the end connected to
the second liquid side communication pipe (22). The refrigerant
temperature sensor (236) serves as refrigerant temperature
detection means.
[0149] The subcooling unit (200) also includes an outside air
temperature sensor (231) and an outdoor fan (230). The outdoor fan
(230) sends outside air to the subcooling outdoor heat exchanger
(222).
[0150] The controller (240) serves as control means. The controller
(240) receives the detection value of the refrigerant temperature
sensor (236), the detection value of the suction pressure sensor
(236), and the detection value of the outside air temperature
sensor (231). The controller (240) controls activation and stop of
the subcooling compressor (221) on the basis of the input detection
values of the sensors. The controller (240) receives none of
signals from the refrigerating apparatus (10) composed of the
outdoor unit (11), the air conditioning unit (12), and the like. In
other words, the controller (240) controls the operation of the
subcooling compressor (221) on the basis of only information
obtained inside the subcooling unit (200), such as detection values
of the sensors provided in the subcooling unit (200).
[0151] -Driving Operation of Refrigeration System-
[0152] Main operations of driving operation that the refrigeration
system performs will be described.
[0153] <Cooling Operation>
[0154] Cooling operation is operation for cooling the inside air of
the cooling showcase (13) and of the refrigeration showcase (14)
and for cooling room air by the air conditioning unit (12) to cool
the store.
[0155] As shown in FIG. 2, during the cooling operation, the first
four-way switching valve (51), the second four-way switching valve
(52), and the third four-way switching valve (53) are set to the
first state. The outdoor expansion valve (46) is closed fully while
each opening of the air conditioning expansion valve (102), the
cooling expansion valve (112), and the refrigeration expansion
valve (132) is adjusted appropriately. In this condition, the
variable capacity compressor (41), the first fixed capacity
compressor (42), the second fixed capacity compressor (43), and the
booster compressor (141) are operated. During the cooling
operation, the subcooling unit (200) is operated. Driving operation
of the subcooling unit (200) will be described later.
[0156] The refrigerant discharged from the variable capacity
compressor (41), the first fixed capacity compressor (42), and the
second fixed capacity compressor (43) is sent to the outdoor heat
exchanger (44) via the first four-way switching valve (51). In the
outdoor heat exchanger (44), the refrigerant radiates heat to
outdoor air to be condensed. The refrigerant condensed in the
outdoor heat exchanger (44) passes through the first liquid pipe
(81), the receiver (45), and the second liquid pipe (82) in this
order, and then, flows into the first liquid side communication
pipe (21).
[0157] The refrigerant flowing in the first liquid side
communication pipe (21) flows into the refrigerant passage (205) of
the subcooling unit (200). The refrigerant flowing in the
refrigerant passage (205) is cooled when passing through the second
flow paths (212) of the subcooling heat exchanger (210). The
subcooled liquid refrigerant cooled in the subcooling heat
exchanger (210) passes through the second liquid side communication
pipe (22), and then, is divided to flow into the air conditioning
circuit (100), the cooling circuit (110), and the refrigeration
circuit (130).
[0158] The refrigerant flowing in the air conditioning circuit
(100) is pressure-reduced when passing through the air conditioning
expansion valve (102), and then, is introduced into the air
conditioning heat exchanger (101). In the air conditioning heat
exchanger (101), the refrigerant absorbs heat from room air to be
evaporated. For the evaporation, the air conditioning heat
exchanger (101) is so set that the evaporation temperature of the
refrigerant is 5.degree. C., for example. The air conditioning unit
(12) supplies the room air cooled in the air conditioning heat
exchanger (101) to the store.
[0159] The refrigerant evaporated in the air conditioning heat
exchanger (101) passes through the second gas side communication
pipe (24), flows into the outdoor circuit (40), passes through the
first four-way switching valve (51) and the second four-way
switching valve (52) in this order, and then, flows into the third
suction pipe (63). Part of the refrigerant flowing in the third
suction pipe (63) passes through the first branch pipe (63a), and
then, is sucked into the second fixed capacity compressor (43)
while the other part thereof passes through the third four-way
switching valve (53) and the second suction pipe (62) in this
order, and then, is sucked into the first fixed capacity compressor
(42).
[0160] The refrigerant flowing in the cooling circuit (100) is
pressure-reduced when passing through the cooling expansion valve
(112), and then, is introduced into the cooling heat exchanger
(111). In the cooling heat exchanger (111), the refrigerant absorbs
heat from the inside air to be evaporated. For the evaporation, the
cooling heat exchanger (111) is so set that the evaporation
temperature of the refrigerant is -5.degree. C., for example. The
refrigerant evaporated in the cooling heat exchanger (111) flows
into the first gas side communication pipe (23). In the cooing
showcase (13), the inside air cooled in the cooling heat exchanger
(111) is supplied thereto so that the inside temperature is kept at
5.degree. C., for example.
[0161] The refrigerant flowing in the refrigeration circuit (130)
is pressure-reduced when passing through the refrigeration
expansion valve (132), and then, is introduced into the
refrigeration heat exchanger (131). In the refrigeration heat
exchanger (131), the refrigerant absorbs heat from the inside air
to be evaporated. For the evaporation, the refrigeration heat
exchanger (131) is so set that the evaporation temperature of the
refrigerant is -30.degree. C., for example. In the refrigeration
showcase (14), the inside air cooled in the refrigeration heat
exchanger (131) is supplied to the inside thereof so that the
inside temperature is kept at -20.degree. C., for example.
[0162] The refrigerant evaporated in the refrigeration heat
exchanger (131) flows into the booster circuit (140) to be sucked
into the booster compressor (141). The refrigerant compressed in
the booster compressor (141) passes through the discharge pipe
(144) and flows into the first gas side communication pipe
(23).
[0163] In the first gas side communication pipe (23), the
refrigerant sent from the cooling circuit (110) and the refrigerant
sent from the booster circuit (140) are combined together. Then,
the combined refrigerant passes through the first gas side
communication pipe (23) and flows into the first suction pipe (61)
of the outdoor circuit (40). The refrigerant flowing in the first
suction pipe (61) passes through the first branch pipe (61a)
thereof to be sucked into the variable capacity compressor
(41).
[0164] <First Heating Operation>
[0165] First heating operation is operation for cooling the inside
air of the cooling showcase (13) and of the refrigeration showcase
(14) and for heating room air by the air conditioning unit (12) to
heat the store.
[0166] As shown in FIG. 3, in the outdoor circuit (40), the first
four-way switching valve (51), the second four-way switching valve
(52), and the third four-way switching valve (53) are set to the
second state, the first state, and the first state, respectively.
The outdoor expansion valve (46) is closed fully while each opening
of the air conditioning expansion valve (102), the cooling
expansion valve (112), and the refrigeration expansion valve (132)
is adjusted appropriately. In this condition, the variable capacity
compressor (41) and the booster compressor (14) are operated while
the first fixed capacity compressor (42) and the second fixed
capacity compressor (43) are stopped. The outdoor heat exchanger
(44) is stopped with no refrigerant sent thereto. During this first
heating operation, the subcooling unit (200) is stopped.
[0167] The refrigerant discharged from the variable capacity
compressor (41) passes through the first four-way switching valve
(51) and the second gas side communication pipe (24) in this order,
is introduced into the air conditioning heat exchanger (101) of the
air conditioning circuit (100), and then, radiates heat to room air
to be condensed. The air conditioning unit (12) supplies the room
air heated in the air conditioning heat exchanger (101) to the
store. The refrigerant condensed in the air conditioning heat
exchanger (101) passes through the second liquid side communication
pipe (22) to be divided to flow into the cooling circuit (110) and
the refrigeration circuit (130).
[0168] In the cooling showcase (13) and the refrigeration showcase
(14), the inside air is cooled, like in the cooling operation. The
refrigerant flowing in the cooling circuit (110) is evaporated in
the cooling heat exchanger (111), and then, flows into the first
gas side communication pipe (23). On the other hand, the
refrigerant flowing in the refrigeration circuit (130) is
evaporated in the refrigeration heat exchanger (131), is compressed
in the booster compressor (141), and then, flows into the first gas
side communication pipe (23). The refrigerant flowing in the first
gas side communication pipe (23) passes through the first suction
pipe (61), and then, is sucked into the variable capacitor
compressor (41) to be compressed.
[0169] As described above, in the first heating operation, the
refrigerant absorbs heat in the cooling heat exchanger (111) and in
the refrigeration heat exchanger (131) while radiating heat in the
air conditioning heat exchanger (101). Then, the store is heated by
utilizing the heat that the refrigerant absorbs from the inside air
of the cooling heat exchanger (111) and of the refrigeration heat
exchanger (131).
[0170] It is noted that the first fixed capacity compressor (42)
may be operated as shown in FIG. 4 during the first heating
operation. The operation of the first fixed capacity compressor
(42) depends on cooling loads in the cooling showcase (13) and the
refrigeration showcase (14). In this case, the third four-way
switching valve (53) is set to the second state. Further, part of
the refrigerant flowing in the first suction pipe (61) passes
through the first branch pipe (61a) thereof to be sucked into the
variable capacity compressor (42) while the other part thereof
passes through the second branch pipe (61b) thereof, the third
four-way switching valve (53), and the second suction pipe (62) in
this order to be sucked into the first fixed capacity compressor
(42).
[0171] <Second Heating Operation>
[0172] Second heating operation is operation for heating the store,
similarly to the first heating operation. The second heating
operation is performed in the case where the heating power in the
first heating operation only is insufficient.
[0173] As shown in FIG. 5, in the outdoor circuit (40), the first
four-way switching valve (51), the second four-way switching valve
(52), and the third four-way switching valve (53) are set to the
second state, the first state, and the first state, respectively.
Each opening of the outdoor expansion valve (46), the air
conditioning expansion valve (102), the cooling expansion valve
(112), and the refrigeration expansion valve (132) is adjusted
appropriately. In this condition, the variable capacity compressor
(41), the second fixed capacity compressor (43), and the booster
compressor (14) are operated while the first fixed capacity
compressor (42) is stopped. During this first heating operation,
the subcooling unit (200) is stopped.
[0174] The refrigerant discharged from the variable capacity
compressor (41) and the second fixed capacity compressor (43)
passes through the first four-way switching valve (51) and the
second gas side communication pipe (24) in this order, is
introduced into the air conditioning heat exchanger (101) of the
air conditioning circuit (100), and then, radiates heat to room air
to be condensed. The air conditioning unit (12) supplies the room
air heated in the air conditioning heat exchanger (101) to the
store. The refrigerant condensed in the air conditioning heat
exchanger (101) flows into the second liquid side communication
pipe (22). Part of the refrigerant flowing in the second liquid
side communication pipe (22) is divided to flow into the cooling
circuit (110) and the refrigeration circuit (130) while the other
part thereof is introduced into the refrigerant passage (205) of
the subcooling unit (200).
[0175] In the cooling showcase (13) and the refrigeration showcase
(14), the inside air is cooled, like in the cooling operation. The
refrigerant flowing in the cooling circuit (110) is evaporated in
the cooling heat exchanger (111), and then, flows into the first
gas side communication pipe (23). On the other hand, the
refrigerant flowing in the refrigeration circuit (130) is
evaporated in the refrigeration heat exchanger (131), is compressed
in the booster compressor (141), and then, flows into the first gas
side communication pipe (23). The refrigerant flowing in the first
gas side communication pipe (23) passes through the first suction
pipe (61), and then, is sucked into the variable capacitor
compressor (41) to be compressed.
[0176] The refrigerant flowing in the refrigerant passage (205) of
the subcooling unit (200) passes through the first liquid side
communication pipe (21) and the third liquid pipe (83) in this
order, flows into the receiver (45), passes through the second
liquid pipe (82), and then, flows into the fourth liquid pipe (84).
The refrigerant flowing in the fourth liquid pipe (84) passes
through the outdoor expansion valve (46) to be pressure-reduced, is
introduced into the outdoor heat exchanger (44), and then, absorbs
heat from outdoor air to be evaporated. The refrigerant evaporated
in the outdoor heat exchanger (44) passes through the first
four-way switching valve (51), the second four-way switching valve
(52) in this order, flows into the second suction pipe (62), and
then, is sucked into the second fixed capacity compressor (43) to
be compressed.
[0177] As described above, in the second heating operation, the
refrigerant absorbs heat in the cooling heat exchanger (111), the
refrigeration heat exchanger (131), and the outdoor heat exchanger
(44) while radiating heat in the air conditioning heat exchanger
(101). Then, the store is heated by utilizing the heat that the
refrigerant absorbs from the inside air in the cooling heat
exchanger (111) and the refrigerant heat exchanger (131) and the
heat that the refrigerant absorbs from outdoor air in the outdoor
heat exchanger (44).
[0178] -Driving Operation of Subcooling Unit-
[0179] Driving operation of the subcooling unit (200) will be
described. In the condition that the subcooling unit (200) is
operated, the subcooling compressor (211) is operated and the
opening of the subcooling expansion valve (223) is adjusted
appropriately.
[0180] As shown in FIG. 1, the subcooling refrigerant discharged
from the subcooling compressor (221) radiates heat to outside air
in the subcooling outdoor heat exchanger (222) to be condensed. The
subcooling refrigerant condensed in the subcooling outdoor heat
exchanger (222) passes through the subcooling expansion valve (223)
to be pressure-reduced, and then, flows into the first flow paths
(211) of the subcooling heat exchanger (210). In the first flow
paths (211) of the subcooling heat exchanger (210), the subcooling
refrigerant absorbs heat from the refrigerant in the second flow
paths (212) to be evaporated. The subcooling refrigerant evaporated
in the subcooling heat exchanger (210) is sucked into the
subcooling compressor (221) to be compressed.
[0181] As described above, the controller (240) controls activation
and stop of the subcooling compressor (221) on the basis of the
detection values input from the sensors. Herein, the control
operation by the controller (240) will be described with reference
to FIG. 6. The control operation of the controller (240) is
repeated every given time period (10 seconds, for example).
[0182] First, in a step ST10, whether the subcooling compressor
(221) is operated or stopped is checked.
[0183] If it is judged in the step ST10 that the subcooling
compressor (221) is operated, the routine proceeds to a step ST11.
In the step ST11, judgment is performed as to whether or not a
predetermined time period (two minutes, for example) has elapsed
from the time point when the subcooling compressor (221) is
activated. If the predetermine time period has elapsed from the
time point when the subcooling compressor (221) is activated, the
routine proceeds to a step ST12. On the other hand, if the
predetermined time period has not elapsed yet, the routine proceeds
to a step ST14 so that the control operation is once terminated for
allowing the subcooling compressor (221) to continue operating.
[0184] In the step ST12, judgment is performed as to whether or not
the subcooling compressor (221) should be stopped. In the step
ST12, judgment is performed as to whether or not the following four
conditions are fulfilled. If at least one of the four conditions is
fulfilled, the routine proceeds to a step ST13 for stopping the
subcooling compressor (221). On the other hand, if none of the four
conditions are fulfilled, the routine proceeds to the step ST14 so
that the control operation is once terminated for allowing the
subcooling compressor (221) to continue operating.
[0185] The first condition in the step ST12 will be described. The
first condition is a condition for judging whether the detection
value of the refrigerant temperature sensor (236) decreases
favorably after activation of the subcooling compressor (221).
[0186] In order to fulfill the first condition in the step ST12,
the following six requirements must be satisfied. The first
requirement requires a detection value Ta of the outdoor
temperature sensor (231) to be below 20.degree. C. (Ta<20). The
second requirement requires a difference between a detection value
Tout#0 of the refrigerant temperature sensor (236) at the time
point when the subcooling compressor (221) is activated and a
detection value Tout#1 of the refrigerant temperature sensor (236)
after one minute elapses from the activation of the subcooling
compressor (221) to be equal to or smaller than 3.degree. C.
(Tout#0-Tout#1.ltoreq.3). The third requirement requires a
difference between the detection value Tout#0 of the refrigerant
temperature sensor (236) at the time point when the subcooling
compressor (221) is activated and a detection value Tout#2 of the
refrigerant temperature sensor (236) after two minutes elapse from
the activation of the subcooling compressor (221) to be equal to or
smaller than 5.degree. C. (Tout#0-Tout#2.ltoreq.5). The fourth
requirement requires a difference between the detection value
Tout#0 of the refrigerant temperature sensor (236) at the time
point when the subcooling compressor (221) is activated and a
detection value Tout#3 of the refrigerant temperature sensor (236)
after three minutes elapse from the activation of the subcooling
compressor (221) to be equal to or smaller than 7.degree. C.
(Tout#0-Tout#3.ltoreq.7). The fifth requirement requires three
minutes to elapse after the time point when the subcooling
compressor (221) is activated. The sixth requirement requires the
refrigerant temperature sensor (236) to operate normally.
[0187] When all of the first to sixth requirements are satisfied,
the detection value Tout of the refrigerant temperature sensor
(236) less decreases even though the temperature of outside air is
not so high and the cooling power is exerted sufficiently in the
subcooling heat exchanger (210). From this aspect, the state that
the first condition in the step ST12 is fulfilled is judged as the
state that the refrigerant does not flow in the refrigerant passage
(205) as in the first heating operation or as the state that the
refrigerant flows towards the outdoor unit (11) in the refrigerant
passage (205) as in the second heating operation. Therefore, when
the first condition is fulfilled, the controller (240) judges that
the refrigerating apparatus (10) is in a driving condition that
necessitates no operation of the subcooling unit (200) to stop the
subcooling compressor (221).
[0188] The second condition in the step ST12 will be described. The
second condition is a condition for judging whether the detection
value of the refrigerant temperature sensor (236) is an appropriate
value corresponding to the evaporation temperature of the
subcooling refrigerant in operation of the subcooling compressor
(221).
[0189] In order to fulfill the second condition in the step ST12,
the following four requirements must be satisfied. The first
requirement requires that five minutes has already elapsed after
the time point when the subcooling compressor (221) is activated.
The second requirement requires the detection value Tout of the
refrigerant temperature sensor (236) to be greater than a value
obtained by adding 15 to an evaporation temperature Tg of the
subcooling refrigerant in the subcooling heat exchanger (210)
(Tout>Tg+15). The third requirement requires the refrigerant
temperature sensor (236) to operate normally. The fourth
requirement requires the suction pressure sensor (234) to operate
normally.
[0190] Wherein, in the controller (240), the saturation temperature
of the subcooling refrigerant in the detection value LP of the
suction pressure sensor (234) is regarded as the evaporation
temperature Tg of the subcooling refrigerant. Namely, in the
present embodiment, the suction pressure sensor (234) serves as
evaporation temperature detection means for detecting the
evaporation temperature of the subcooling refrigerant.
[0191] When all of the first to fourth requirements are satisfied,
the difference between the detection value Tout of the refrigerant
temperature sensor (236) and the evaporation temperature Tg of the
subcooling refrigerant is greater than 15.degree. C. even though
the subcooling refrigerant circuit (220) is performing the
refrigeration cycle. From this aspect, the state that the second
condition in the step ST12 is fulfilled is judged also as the state
that the refrigerant does not flow in the refrigerant passage (205)
as in the first heating operation or as the state that the
refrigerant flows towards the outdoor unit (11) in the refrigerant
passage (205) as in the second heating operation. Therefore, when
the second condition is fulfilled, the controller (240) judges that
the refrigerating apparatus (10) is in a driving condition that
necessitates no operation of the subcooling unit (200) to stop the
subcooling compressor (221).
[0192] The third condition in the step ST12 will be described. The
third condition is satisfied when the detection value LP of the
suction pressure sensor (234) is below 0.2 MPa and the suction
pressure sensor operates abnormally. If satisfied, the detection
value of the suction pressure sensor (234) would be abnormal, and
therefore, the operation of the subcooling compressor (221) could
not be controlled properly with the abnormal detection value.
Accordingly, when the third condition is satisfied, the controller
(240) stops the operation of the subcooling compressor (221).
[0193] The fourth condition in the step ST12 will be described. The
fourth condition is satisfied when the detection value LP of the
suction pressure sensor (234) is below 0.15 MPa. When satisfied,
the detection value of the suction pressure sensor (234) is small
to such an extent that the pressure never reaches the value in the
normal operation. Therefore, when the fourth condition is
satisfied, the controller (240) judges that some trouble occurs to
stop the subcooling compressor (221).
[0194] If it is judged in the step ST1 that the subcooling
compressor (221) is stopped, the routine proceeds to a step ST15.
In the step ST15, whether a predetermined time period has elapsed
from the time point when the subcooling compressor (221) is stopped
is judged. In order to avoid repetition of activation and stop of
the subcooling compressor (221) within a short period of time,
after the subcooling compressor (221) is stopped once,
re-activation of the subcooling compressor (221) is restrained
until a given period of time elapses from the stop. In the step
ST15, if the predetermined time period has not elapsed from the
time point when the subcooling compressor (221) is stopped, the
routine proceeds to the step ST14 so that the control operation is
once terminated for keeping the subcooling compressor (221)
stopping. On the other hand, if the predetermined time period has
elapsed from the time point when the subcooling compressor (221) is
stopped, the routine proceeds to a step ST16.
[0195] In the step ST16, whether or not the subcooling compressor
(221) should be activated is judged. In the step ST16, judgment is
performed as to whether or not the following three conditions are
fulfilled. When at least one of the three conditions is fulfilled,
the routine proceeds to a step ST17 so that the subcooling
compressor (221) is activated. On the other hand, if none of the
three conditions are fulfilled, the routine proceeds to the step
ST14 so that the control operation is once terminated for keeping
the subcooling compressor (221) stopping.
[0196] The first condition in the step ST16 will be described. The
first condition is fulfilled when the detection value Ta of the
outside air temperature sensor (231) is equal to or greater than
25.degree. C. and one minute has elapsed from the time point when
the subcooling compressor (221) is stopped. In this state, the
subcooling compressor (221) is stopped for one or more minutes even
though the temperature of outside air is rather high. Therefore,
when the first condition is fulfilled, the controller (240)
activates the subcooling compressor (221) for cooling the
refrigerant in the refrigerant passage (205).
[0197] The second condition in the step ST16 will be described. The
second condition is fulfilled when the detection value Ta of the
outside air temperature sensor (231) is equal to or greater than
20.degree. C. and three minutes have elapsed from the time point
when the subcooling compressor (221) is stopped. In this state, the
subcooling compressor (221) is stopped for three or more minutes
even though the temperature of outside air is comparatively high.
Therefore, when the second condition is fulfilled, the controller
(240) activates the subcooling compressor (221) for cooling the
refrigerant in the refrigerant passage (205).
[0198] The third condition in the step ST16 will be described. The
third condition is fulfilled when ten minutes have already elapsed
from the time point when the subcooling compressor (221) is
stopped. In this state, the subcooling compressor (221) is stopped
for a comparatively long period of time. Therefore, when the third
condition is fulfilled, the controller (240) activates the
subcooling compressor (221) for cooling the refrigerant in the
refrigerant passage (205). In this way, the controller (240) never
fails to activate the subcooling compressor (221) upon a lapse of
ten minutes after the time point when the subcooling compressor
(221) is stopped.
[0199] -Effects of Embodiment-
[0200] In the subcooling unit (200), the controller (240) controls
the operation of the subcooling compressor (221) on the basis of
only information obtained within the subcooling unit (200), such as
the detection value of a sensor provided in the subcooling unit
(200). In other words, in the subcooling unit (200), the operation
of the subcooling compressor (221) can be controlled according to
the operation state of the refrigerating apparatus (10) without
sending and receiving a signal to and from the refrigerating
apparatus (10). As a result, for incorporating the subcooling unit
(200) to the refrigerating apparatus (10), only connection of the
refrigerant passage (205) of the subcooling unit (200) to the first
and second liquid side communication pipes (21, 22) of the
refrigerating apparatus (10) is required. This eliminates the need
to wire any communication wirings for sending and receiving a
signal between the refrigerating apparatus (10) and the subcooling
unit (200).
[0201] Hence, according to the present embodiment, the number of
operation steps for incorporating the subcooling unit (200) to the
refrigerating apparatus (10) can be reduced and troubles caused due
to human errors in installation, such as mis-wiring, can be
obviated.
[0202] In order to send and receive a signal between the subcooling
unit (200) and the refrigerating apparatus (10), a communication
interface is needed at the refrigerating apparatus (10) as well as
at the subcooling unit (200). For this reason, in the case where
operation control of a subcooling unit (200) requires signal input
from a refrigerating apparatus (10), an applicable type of the
refrigerating apparatus (10) is limited, resulting in poor
usability of the subcooling unit (200).
[0203] In contrast, the subcooling unit (200) in the present
embodiment eliminates the need to send and receive any signal to
and from the refrigerating apparatus (10) and no limitation is
imposed on the type of the refrigerating apparatus (10) as an
object to which the subcooling unit (200) is to be incorporated.
Hence, in the present embodiment, the limitation on the type of the
refrigerating apparatus (10) as an object to which the subcooling
unit (200) is to be incorporated is eliminated, thereby enhancing
the usabilty of the subcooling unit (200) remarkably.
MODIFIED EXAMPLE 1 OF EMBODIMENT
[0204] The subcooling unit (200) of the present embodiment may
include temperature sensors (237, 238) on the respective sides of
the subcooling heat exchanger (210) in the refrigerant passage
(205) in order to control the operation of the subcooling
compressor (221) on the basis of the detection values of the
temperature sensors (237, 238).
[0205] As shown in FIG. 7, in the refrigerant passage (205), the
first refrigerant temperature sensor (237) is provided at a part
nearer the other end than the subcooling heat exchanger (210), that
is, a part near the end portion connected to the second liquid side
communication pipe (22). Also, in the refrigerant passage (205),
the second refrigerant temperature sensor (238) is provided at a
part nearer the one end than the subcooling heat exchanger (210),
that is, a part near the end portion connected to the first liquid
side communication pipe (21). In this subcooling unit (200), the
first refrigerant temperature sensor (237) and the second
refrigerant temperature sensor (238) serve as first refrigerant
temperature detection means and second refrigerant temperature
detection means, respectively.
[0206] The controller (240) of the present modified example
receives the detection value of the first refrigerant temperature
sensor (237) and the detection value of the second refrigerant
temperature sensor (238). The controller (240) compares the
detection values of the refrigerant temperature sensors (237, 238)
during operation of the subcooling compressor (221) to determine
whether the operation of the subcooling compressor (221) should be
continued or stopped according to the comparison result.
[0207] Control operation by the controller (240) will be
described.
[0208] First, the state that the detection value of the first
refrigerant temperature sensor (237) is smaller than the detection
value of the second refrigerant temperature sensor (238) in
operation of the subcooling compressor (221) means that the
temperature of the refrigerant cooled in the subcooling heat
exchanger (210) is detected by the first refrigerant temperature
sensor (237). From this aspect, this state can be judged as the
state that the refrigerant flows from the first liquid side
communication pipe (21) towards the second liquid side
communication pipe (22) in the refrigerant passage (205) as in the
cooling operation, and therefore, the controller (240) allows the
subcooling compressor (221) to continue operating.
[0209] In reverse, the state that the detection value of the second
refrigerant temperature sensor (238) is smaller than the detection
value of the first refrigerant temperature sensor (237) in
operation of the subcooling compressor (221) means that the
temperature of the refrigerant cooled in the subcooling heat
exchanger (210) is detected by the second refrigerant temperature
sensor (238). From this aspect, this state can be judged as the
state that the refrigerant flows from the second liquid side
communication pipe (22) towards the first liquid side communication
pipe (21) in the refrigerant passage (205) as in the second heating
operation, and therefore, the controller (240) stops the operation
of the subcooling compressor (221).
[0210] Further, the state that the detection value of the first
refrigerant temperature sensor (237) and the detection value of the
second refrigerant temperature sensor (238) are almost equal to
each other in operation of the subcooling compressor (221) can be
judged as the state that the refrigerant does not flows in the
refrigerant passage (205) as in the first heating operation, and
therefore, the controller (240) stops the operation of the
subcooling compressor (221).
[0211] It is noted that in the controller (240) of the present
modified example, the difference between the detection value of the
first refrigerant temperature sensor (237) and the detection value
of the second refrigerant temperature sensor (238) may be used as a
flowing state indication value that indicates the flowing state of
the refrigerant in the refrigerant passage (205). Specifically, the
state that a value obtained by subtracting the detection value of
the second refrigerant temperature sensor (238) from the detection
value of the first refrigerant temperature sensor (237) is negative
can be judged as the state that the detection value of the first
refrigerant temperature sensor (237) is smaller than the detection
value of the second refrigerant temperature sensor (238).
Therefore, the controller (240) allows the subcooling compressor
(221) to continue operating. Further, the state that a value
obtained by subtracting the detection value of the second
refrigerant temperature sensor (238) from the detection value of
the first refrigerant temperature sensor (237) is equal to or
greater than 0 can be judged as the state that the detection value
of the first refrigerant temperature sensor (237) is equal to or
greater than the detection value of the second refrigerant
temperature sensor (238). Therefore, the controller (240) stops the
operation of the subcooling compressor (221).
MODIFIED EXAMPLE 2 OF EMBODIMENT
[0212] In the subcooling unit (200) of the present embodiment, a
flow mater (251) may be provided at the refrigerant passage (205)
in order to control the operation of the subcooling compressor
(221) on the basis of the detection value of the flow meter
(251).
[0213] In this subcooling unit (200), the controller (240) receives
the detection value of the flow meter (251). The controller (240)
judges, on the basis of the detection value of the flow meter
(251), the flowing direction of the refrigerant in the refrigerant
passage (205) and whether or not the refrigerant flows in the
refrigerant passage (205). In other words, the controller (240)
uses the detection value of the flow meter (251) as a flowing state
indication value that indicates the flowing state of the
refrigerant in the refrigerant passage (205).
[0214] When it is judged that the refrigerant flows from the first
liquid side communication pipe (21) towards the second liquid side
communication pipe (22) in the refrigerant passage (205) in
operation of the subcooling compressor (221), the controller (240)
allows the subcooling compressor (221) to continue operating. When
it is judged that the refrigerant flows from the second liquid side
communication pipe (22) towards the first liquid side communication
pipe (21) in the refrigerant passage (205) in operation of the
subcooling compressor (221) or that the refrigerant does not flow
in the refrigerant passage (205) in operation of the subcooling
compressor (221), the controller (240) stops the operation of the
subcooling compressor (221).
MODIFIED EXAMPLE 3 OF EMBODIMENT
[0215] The controller (24) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
only the detection value of the outside air temperature sensor
(231).
[0216] Operation of this controller (240) will be described. The
state that the detection value of the outside air temperature
sensor (231) is greater than a predetermined upper limit value
(30.degree. C., for example) can be estimated as the state that the
cooling load in the cooling showcase (13) or the refrigeration
showcase (14) or the cooling load in the air conditioning unit (12)
is high. Therefore, in this state, the controller (240) activates
the subcooling compressor (221) if the subcooling compressor (221)
is stopped or allows the subcooling compressor (221) to continue
operating if the subcooling compressor (221) is operated. The
refrigerant flowing from the first liquid side communication pipe
(21) towards the second liquid side communication pipe (22) in the
refrigerant passage (205) is supplied to the cooling showcase (13)
and the like after cooled in the subcooling heat exchanger
(210).
[0217] In reverse, the state that the detection value of the
outside air temperature sensor (231) is smaller than a
predetermined lower limit value (20.degree. C., for example) can be
estimated as the state that the cooling load in the cooling
showcase (13) or the refrigeration showcase (14) or the cooling
load in the air conditioning unit (12) is low. From this aspect,
this state can be judged as the state that the operation of the
subcooling compressor (221) is unnecessary. Therefore, in this
state, the controller (240) keeps the subcooling compressor (221)
being stopped if the subcooling compressor (221) is stopped or
stops the operation of the subcooling compressor (221) if the
subcooling compressor (221) is operated.
MODIFIED EXAMPLE 4 OF EMBODIMENT
[0218] The controller (240) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
only variation in detection value of the refrigerant temperature
detection means (236). The controller (240) in the present modified
example uses variation in detection value of the refrigerant
temperature detection means (236) as a flowing state indication
value that indicates the flowing state of the refrigerant in the
refrigerant passage (205).
[0219] Operation of this controller (240) will be described. The
state that the detection value of the refrigerant temperature
detection means (236) gradually decreases from the time point when
the subcooling compressor (221) is activated can be judged as the
state that the refrigerant flows from the first liquid side
communication pipe (21) towards the second liquid side
communication pipe (22) in the refrigerant passage (205). In this
state, therefore, the controller (240) allows the subcooling
compressor (221) to continue operating.
[0220] In reverse, the state that the detection value of the
refrigerant temperature detection means (236) does not decrease
after activation of the subcooling compressor (221) can be judged
as the state that the refrigerant flows from the second liquid side
communication pipe (22) towards the first liquid side communication
pipe (21) in the refrigerant passage (205) or as the state that the
refrigerant does not flow in the refrigerant passage (205). In this
state, therefore, the controller (240) stops the operation of the
subcooling compressor (221).
[0221] Further, the state that the detection value of the
refrigerant temperature detection means (236) gradually increases
from the time point when the subcooling compressor (221) is stopped
can be judged as the state that the refrigerant flows from the
first liquid side communication pipe (21) towards the second liquid
side communication pipe (22) in the refrigerant passage (205). In
this state, therefore, the controller (240) activates the
subcooling compressor (221) again.
[0222] In reverse, the state that the detection value of the
refrigerant temperature detection means (236) does not increase
even in the time when the subcooling compressor (221) is stopped
can be judged as the state that the refrigerant flows from the
second liquid side communication pipe (22) towards the first liquid
side communication pipe (21) in the refrigerant passage (205) or as
the state that the refrigerant does not flow in the refrigerant
passage (205). In this state, therefore, the controller (240) keeps
the subcooling compressor (221) being stopped.
MODIFIED EXAMPLE 5 OF EMBODIMENT
[0223] The controller (240) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
difference in temperature of the subcooling refrigerant between at
the inlet and at the outlet of the first flow paths (221) of the
subcooling heat exchanger (210).
[0224] As shown in FIG. 9, the subcooling unit (200) of the present
modified example includes a first subcooling refrigerant
temperature sensor (252) and a second subcooling refrigerant
temperature sensor (253). In the subcooling refrigerant circuit
(220), the first subcooling refrigerant temperature sensor (252) is
provided immediately before the first flow paths (211) of the
subcooling heat exchanger (210) for detecting the temperature of
the subcooling refrigerant that is to flow into the first flow
paths (211). On the other hand, the second subcooling refrigerant
temperature sensor (253) is provided immediately after the first
flow paths (211) of the subcooling heat exchanger (210) for
detecting the temperature of the subcooling refrigerant immediately
after flowing out from the first flow paths (211). The controller
(240) of the present modified example uses the difference between
the detection value of the first subcooling refrigerant temperature
sensor (252) and the detection value of the second subcooling
refrigerant temperature sensor (253) as a flowing state indication
value that indicates the flowing state of the refrigerant in the
refrigerant passage (205)
[0225] Operation of this controller (240) will be described. The
state that the detection value of the second subcooling refrigerant
temperature sensor (253) is greater than the detection value of the
first subcooling refrigerant temperature sensor (252) (that is, the
state that a value obtained by subtracting the detection value of
the first subcooling refrigerant temperature sensor (252) from the
detection value of the second subcooling refrigerant temperature
sensor (253) is positive (+)) in operation of the subcooling
compressor (221) can be judged as the state that the refrigerant
flows from the first liquid side communication pipe (21) towards
the second liquid side communication pipe (22) in the refrigerant
passage (205). In this state, therefore, the controller (240)
allows the subcooling compressor (221) to continue operating.
[0226] In reverse, the state that the detection value of the second
subcooling refrigerant temperature sensor (253) is smaller than the
detection value of the first subcooling refrigerant temperature
sensor (252) or the state that there is no difference therebetween
(that is, the state that a value obtained by subtracting the
detection value of the first subcooling refrigerant temperature
sensor (252) from the detection value of the second subcooling
refrigerant temperature sensor (253) is equal to or smaller than 0)
in operation of the subcooling compressor (221) can be judged as
the state that the refrigerant flows from the second liquid side
communication pipe (22) towards the first liquid side communication
pipe (21) in the refrigerant passage (205) or as the state that the
refrigerant does not flow in the refrigerant passage (205). In this
state, therefore, the controller (240) stops the operation of the
subcooling compressor (221).
MODIFIED EXAMPLE 6 OF EMBODIMENT
[0227] The controller (240) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
only the detection value of the suction pressure sensor (234). The
detection value of the suction pressure sensor (234) is
substantially equal to the refrigerant pressure in the first flow
paths (211) of the subcooling heat exchanger (210), that is, the
evaporation pressure of the subcooling refrigerant. Thus, the
suction pressure sensor (234) in the present modified example
serves as evaporation pressure detection means. The controller
(240) of the present modified example uses the detection value of
the suction pressure sensor (234) as a flowing state indication
value that indicates the flowing state of the refrigerant in the
refrigerant passage (205).
[0228] Operation of this controller (240) will be described. The
detection value of the suction pressure sensor (234) being greater
than a predetermined reference value (0.2 MPa, for example) in
operation of the subcooling compressor (210) means evaporation of
the subcooling refrigerant in the first flow paths (211) of the
subcooling heat exchanger (210), and in turn, can be judged as the
state that the refrigerant flows in the refrigerant passage (205).
Therefore, in this state, the controller (240) allows the
subcooling compressor (221) to continue operating.
[0229] In reverse, the detection value of the suction pressure
sensor (234) being equal to or smaller than the predetermined
reference value in operation of the subcooling compressor (210)
means no or less evaporation of the subcooling refrigerant in the
first flow paths (211) of the subcooling heat exchanger (210), and
in terun, can be judged as the state that the refrigerant does not
flow in the refrigerant passage (205). Therefore, in this state,
the controller (240) stops the operation of the subcooling
compressor (221).
MODIFIED EXAMPLE 7 OF EMBODIMENT
[0230] The controller (240) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
only the difference between the detection value Tout of the
refrigerant temperature sensor (236) and the evaporation
temperature Tg of the subcooling refrigerant. The controller (240)
of the present modified example uses the difference between the
detection value Tout of the refrigerant temperature sensor (236)
and the evaporation temperature Tg of the subcooling refrigerant as
a flowing state indication value that indicate the flowing state of
the refrigerant in the refrigerant passage (205).
[0231] Operation of this controller (240) will be described. The
state that a value obtained by subtracting the evaporation
temperature Tg of the subcooling refrigerant from the detection
value Tout of the refrigerant temperature sensor (236) is equal to
or smaller than a predetermined reference value (15.degree. C., for
example) in operation of the subcooling compressor (221) is judged
as the state that the refrigerant flows from the first liquid side
communication pipe (21) towards the second liquid side
communication pipe (22) in the refrigerant passage (205). In this
state, therefore, the controller (240) allows the subcooling
compressor (221) to continue operating.
[0232] In reverse, the state that a value obtained by subtracting
the evaporation temperature Tg of the subcooling refrigerant from
the detection value Tout of the refrigerant temperature sensor
(236) is equal to or smaller than the predetermined reference value
in operation of the subcooling compressor (221) is judged as the
state that the refrigerant flows from the second liquid side
communication pipe (22) towards the first liquid side communication
pipe (21) in the refrigerant passage (205) or as the state that the
refrigerant does not flow in the refrigerant passage (205). In this
state, therefore, the controller (240) stops the operation of the
subcooling compressor (221).
MODIFIED EXAMPLE 8 OF EMBODIMENT
[0233] The controller (240) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
only the detection value of the refrigerant temperature detection
means (236). The controller (240) of the present modified example
uses the detection value of the refrigerant temperature detection
means (236) as a flowing state indication value that indicates the
flowing state of the refrigerant in the refrigerant passage
(205).
[0234] Operation of this controller (240) will be described. The
state that the detection value of the refrigerant temperature
detection means (236) is greater than a predetermined reference
value in non-operation of the subcooling compressor (221) can be
estimated as the state that the cooling power in the cooling
showcase (13) or the like is insufficient to some extent because of
high temperature of the refrigerant sent from the outdoor unit (11)
to the utility side such as the cooling showcase (13) or the like.
Therefore, in this state, the controller (240) activates the
subcooling compressor (221).
[0235] In reverse, the state that the detection value of the
refrigerant temperature detection means (236) is equal to or
smaller than the predetermined reference value in non-operation of
the subcooling compressor (221) can be estimated as the state that
the cooling power in the cooling showcase (13) or the like is
secured sufficiently because of not-so-high temperature of the
refrigerant sent from the outdoor unit (11) to the utility side
such as the cooling showcase (13) or the like. Therefore, in this
state, the controller (240) keeps the subcooling compressor (221)
being stopped.
MODIFIED EXAMPLE 9 OF EMBODIMENT
[0236] The controller (240) of the present embodiment may control
the operation of the subcooling compressor (221) on the basis of
the difference between the detection value of the refrigerant
temperature detection means (236) and the detection value of the
outside air temperature sensor (231). The controller (240) of the
present modified example uses the difference between the detection
value of the refrigerant temperature detection means (236) and the
detection value of the outside air temperature sensor (231) as a
flowing state indication value that indicates the flowing state of
the refrigerant in the refrigerant passage (205).
[0237] Operation of this controller (240) will be described. When
the refrigerant flows from the first liquid side communication pipe
(21) towards the second liquid side communication pipe (22) in the
refrigerant passage (205), the refrigerant condensed by radiating
heat to outdoor air in the outdoor heat exchanger (44) flows into
the refrigerant passage (205), wherein the temperature of this
refrigerant never becomes smaller than the temperature of the
outdoor air. From this aspect, the state that a value obtained by
subtracting the detection value of the outside air temperature
sensor (231) from the detection value of the refrigerant
temperature detection means (236) is greater than a predetermined
reference value in non-operation of the subcooling compressor (221)
can be judged as the state that the refrigerant flows from the
first liquid side communication pipe (21) towards the second liquid
side communication pipe (22) in the refrigerant passage (205).
Therefore, in this state, the controller (240) activates the
subcooling compressor (221).
[0238] In reverse, the state that a value obtained by subtracting
the detection value of the outside air temperature sensor (231)
from the detection value of the refrigerant temperature detection
means (236) is equal to or smaller than the predetermined reference
value in non-operation of the subcooling compressor (221) can be
judged as the state that the refrigerant flows from the second
liquid side communication pipe (22) towards the first liquid side
communication pipe (21) in the refrigerant passage (205) or as the
state that the refrigerant does not flow in the refrigerant passage
(205). Therefore, in this state, the controller (240) keeps the
subcooling compressor (221) being stopped.
MODIFIED EXAMPLE 10 OF EMBODIMENT
[0239] In the subcooling unit (200) of the present embodiment, the
subcooling refrigerant circuit (220) may be so composed that the
refrigerant naturally circulates.
[0240] As shown in FIG. 10, in the subcooling refrigerant circuit
(220) of the present modified example, the subcooling outdoor heat
exchanger (222) is arranged upper than the subcooling heat
exchanger (210). Further, the subcooling refrigerant circuit (222)
includes a bypass pipe (224). The bypass pipe (224) is connected at
one end thereof to the suction side of the subcooling compressor
(221) and at the other end thereof to the discharge side of the
subcooling compressor (221). In addition, the bypass pipe (224)
includes a check valve (225) for allowing the refrigerant to flow
from the one end towards the other end thereof.
[0241] In the subcooling refrigerant circuit (220), the subcooling
refrigerant circulates by operating the outdoor fan (230) even in
non-operation of the subcooling compressor (221). Specifically,
when the outdoor fan (230) is operated, the refrigerant radiates
heat to outdoor air in the subcooling outdoor heat exchanger (222)
to be condensed. The subcooling refrigerant condensed in the
subcooling outdoor heat exchanger (222) falls down by gravitation
to pass through the subcooling expansion valve (223) set to be
opened fully, and then, flows into the first flow paths (211) of
the subcooling heat exchanger (210). In the first flow paths (211)
of the subcooling heat exchanger (210), the subcooling refrigerant
absorbs heat from the refrigerant of the second passages (212) to
be evaporated. The subcooling refrigerant evaporated in the
subcooling heat exchanger (210) passes through the bypass pipe
(224) to return to the subcooling outdoor heat exchanger (222),
thereby being condensed again by heat exchange with outdoor
air.
[0242] For activating the subcooling unit (200), the controller
(240) of the present modified example activates the outdoor fan
(230) first and judges whether or not the subcooling compressor
(221) should be activated in the condition that the outdoor fan
(230) is operated. Specifically, upon judgment that the refrigerant
flowing in the refrigerant passage (205) should be cooled, the
controller (240) activates only the outdoor fan (230) with the
subcooling compressor (221) stopped. When the outdoor fan (230) is
activated, the subcooling refrigerant naturally circulates in the
refrigerant passage (205) while the refrigerant in the second flow
paths (212) is cooled by the subcooling refrigerant in the
subcooling heat exchanger (210). The controller (240) allows only
the outdoor fan (230) to continue operating for a predetermined
time period (five minutes, for example), and then, judges whether
or not the refrigerant flowing in the refrigerant passage (205) is
cooled sufficiently. When the refrigerant flowing in the
refrigerant passage (205) is cooled insufficiently, the controller
(240) activates the subcooling compressor (221). When the
subcooling compressor (221) is activated, the subcooling
refrigerant circuit (220) performs the refrigeration cycle. In
reverse, when the refrigerant is sufficiently cooled, the
controller (240) allows only the outdoor fan (230) to continue
operating with the subcooling compressor (221) kept stopping.
[0243] In the present modified example, the subcooling compressor
(221) is activated only when only the natural circulation of the
subcooling refrigerant by the operation of the outdoor fan (230) is
insufficient for cooling the heat source side refrigerant.
Accordingly, the situation that the subcooling compressor (221) is
activated even when the activation of the subcooling compressor
(221) is unnecessary can be avoided, reducing the number of times
of activation of the subcooling compressor (221). As a result, the
time period when the subcooling compressor (221) falls in an
unstable transient state in its operation can be shortened,
increasing the reliability of the subcooling compressor (221).
MODIFIED EXAMPLE 11 OF EMBODIMENT
[0244] The subcooling unit (200) of the present embodiment may
include, as the cooling fluid circuit, a cold water circuit in
which cold water flows rather than the subcooling refrigerant
circuit (220). In this cold water circuit, water at comparatively
low temperature, for example, at a temperature of approximately
5.degree. C. flows. In the subcooling heat exchanger (210) of the
present modified example, the cold water circuit is connected to
the first flow paths (211) so that the cold water flowing in the
first flow paths (211) is heat-exchanged with the refrigerant
flowing in the second flow paths (212).
[0245] It should be noted that the above embodiments are
substantially preferred examples and do not intend to limit the
scopes of the present invention, applicable objects, and use
thereof.
INDUSTRIAL APPLICABILITY
[0246] As described above, the present invention is useful in
subcooling apparatuses for cooling refrigerant sent from a heat
source unit to a utility unit in a refrigerating apparatus.
* * * * *