U.S. patent application number 17/641551 was filed with the patent office on 2022-09-22 for refrigeration cycle apparatus.
The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Hiroki MARUYAMA, Takuya MATSUDA, Shuhei MIZUTANI.
Application Number | 20220299247 17/641551 |
Document ID | / |
Family ID | 1000006431934 |
Filed Date | 2022-09-22 |
United States Patent
Application |
20220299247 |
Kind Code |
A1 |
MATSUDA; Takuya ; et
al. |
September 22, 2022 |
REFRIGERATION CYCLE APPARATUS
Abstract
A refrigeration cycle apparatus includes a compressor, an
expansion valve, a flow switching device, a heat source side heat
exchanger including a first heat source side heat exchanger and a
second heat source side heat exchanger connected in parallel, an
opening-and-closing valve provided on downstream of the second heat
source side heat exchanger through which refrigerant flows during a
defrosting operation, and a controller that, when the defrosting
operation is performed, controls the flow switching device so that
the refrigerant discharged from the compressor flows into the heat
source side heat exchanger. The controller switches the
opening-and-closing valve from an open state to a closed state when
the defrosting operation is started, determines a point in time
when defrosting targets to be defrosted are switched, and switches
the opening-and-closing valve from the closed state to the open
state in accordance with the point in time determined.
Inventors: |
MATSUDA; Takuya; (Tokyo,
JP) ; MIZUTANI; Shuhei; (Tokyo, JP) ;
MARUYAMA; Hiroki; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
1000006431934 |
Appl. No.: |
17/641551 |
Filed: |
November 12, 2019 |
PCT Filed: |
November 12, 2019 |
PCT NO: |
PCT/JP2019/044375 |
371 Date: |
March 9, 2022 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F25B 49/02 20130101;
F25B 41/20 20210101; F25B 2313/02741 20130101; F25B 47/025
20130101; F25B 13/00 20130101; F25B 2313/0314 20130101 |
International
Class: |
F25B 47/02 20060101
F25B047/02; F25B 41/20 20060101 F25B041/20; F25B 49/02 20060101
F25B049/02; F25B 13/00 20060101 F25B013/00 |
Claims
1. A refrigeration cycle apparatus comprising: a compressor
configured to compress and discharge refrigerant; an expansion
valve configured to reduce pressure of the refrigerant to cause the
refrigerant to expand; a load side heat exchanger connected to the
expansion valve; a four-way valve connected to the compressor and
the load side heat exchanger; a heat source side heat exchanger
including a first heat source side heat exchanger and a second heat
source side heat exchanger connected in parallel between the
four-way valve and the expansion valve; a gas pipe configured to
join a first gas pipe connected to the first heat source side heat
exchanger and a second gas pipe connected to the second heat source
side heat exchanger to allow the first gas pipe and the second gas
pipe to communicate with the flow switching device; a first gas
header configured to split the refrigerant flowing into the first
heat source side heat exchanger including a plurality of first
heat-transfer tubes from the compressor via the four-way valve into
streams flowing through the plurality of first heat-transfer tubes;
a second gas header configured to split the refrigerant flowing
into the second heat source side heat exchanger including a
plurality of second heat-transfer tubes from the compressor via the
four-way valve into streams flowing through the plurality of second
heat-transfer tubes; an opening-and-closing valve provided on
downstream of the second heat source side heat exchanger through
which the refrigerant flows during a defrosting operation; and a
controller configured to, when the defrosting operation is
performed, control the four-way valve so that the refrigerant
discharged from the compressor flows into the heat source side heat
exchanger, wherein a number of the plurality of first heat-transfer
tubes is larger than a number of the plurality of second
heat-transfer tubes, the first gas pipe is connected to a middle
portion in a gravity direction of the first gas header, the second
gas pipe is connected to a middle portion in the gravity direction
of the second gas header, and the controller is configured to
switch the opening-and-closing valve from an open state to a closed
state when the defrosting operation is started, determine a point
in time when defrosting targets to be defrosted are switched, and
switch the opening-and-closing valve from the closed state to the
open state in accordance with the point in time determined.
2-3. (canceled)
4. The refrigeration cycle apparatus of claim 1, further comprising
a temperature sensor provided on the downstream of the second heat
source side heat exchanger and configured to detect a temperature
of the refrigerant, wherein the controller is configured to
determine, as the point in time, a time when a value detected by
the temperature sensor reaches not less than a predetermined
temperature threshold.
5. The refrigeration cycle apparatus of claim 1, further comprising
a flow control valve provided on downstream of the first heat
source side heat exchanger through which the refrigerant flows
during the defrosting operation, wherein, when the defrosting
operation is started, the controller is configured to maintain the
flow control valve in an open state and switch the
opening-and-closing valve from an open state to a closed state, and
wherein, in accordance with the point in time determined, the
controller is configured to switch the flow control valve from the
open state to a closed state and switch the opening-and-closing
valve from the closed state to the open state.
6. The refrigeration cycle apparatus of claim 5, further comprising
a temperature sensor provided on the downstream of the first heat
source side heat exchanger and configured to detect a temperature
of the refrigerant, wherein the controller is configured to
determine, as the point in time, a time when a value detected by
the temperature sensor reaches not less than a predetermined
temperature threshold.
7. The refrigeration cycle apparatus of claim 1, wherein the
controller further includes a timer configured to measure a time
period, and wherein the controller is configured to determine, as
the point in time, a time when a time period measured from start of
the defrosting operation by the timer reaches not less than a
predetermined time threshold.
8. The refrigeration cycle apparatus of claim 1, further
comprising: a third heat source side heat exchanger connected in
parallel with the first heat source side heat exchanger and the
second heat source side heat exchanger between the four-way valve
and the expansion valve; a first flow control valve provided on
downstream of the first heat source side heat exchanger through
which the refrigerant flows during the defrosting operation; and a
second flow control valve provided on downstream of the third heat
source side heat exchanger through which the refrigerant flows
during the defrosting operation, wherein, when the defrosting
operation is started, the controller is configured to maintain the
first flow control valve in an open state and switch the
opening-and-closing valve and the second flow control valve from an
open state to a closed state, wherein, in accordance with the point
in time determined, the controller is configured to switch the
first flow control valve from the open state to a closed state and
switch the opening-and-closing valve from the closed state to the
open state, and wherein, after switching the opening-and-closing
valve from the closed state to the open state, in accordance with
the point in time determined, the controller is configured to
switch the opening-and-closing valve from the open state to the
closed state and switch the second flow control valve from the
closed state to the open state.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a U.S. National Stage Application of
International Application No. PCT/JP2019/044375 filed on Nov. 12,
2019, the contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present disclosure relates to a refrigeration cycle
apparatus that conditions air in an air-conditioned space.
BACKGROUND
[0003] In an existing air-conditioning apparatus, there is a heat
exchanger including a plurality of flat pipes that are vertically
arrayed and each have a refrigerant passage, and a plurality of
fins that partition a space between adjacent flat pipes into a
plurality of air flow passages through which air flows (for
example, see Patent Literature 1).
[0004] A heat exchanger disclosed in Patent Literature 1 includes a
main heat exchange section, and a sub heat exchange section
provided at a position different from a position of the main heat
exchange section in a vertical direction and connected in series
with the main heat exchange section. In the main heat exchange
section, many flat pipes are provided in comparison with the sub
heat exchange section located downstream of the main heat exchange
section. Furthermore, a lowermost flat pipe in the heat exchanger
is provided in a main heat exchanger located upstream of the sub
heat exchange section. This configuration reduces the time taken to
melt frost that has adhered to a lowermost heat exchange section
during a defrosting operation.
PATENT LITERATURE
[0005] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2019-11941
[0006] In an air conditioner disclosed in Patent Literature 1, in
the defrosting operation, refrigerant discharged from a compressor
passes through the main heat exchange section and then flows into
the sub heat exchange section. That is, even after defrosting of
the main heat exchange section is finished, the refrigerant
discharged from the compressor flows through the main heat exchange
section before flowing into the sub heat exchange section. For this
reason, before the heat of the refrigerant reaches the sub heat
exchange section, heat exchange between the refrigerant and air is
performed in the main heat exchange section in which defrosting is
unnecessary, and the heat is uselessly released. Consequently,
defrosting is unable to be efficiently performed.
SUMMARY
[0007] The present disclosure has been made to overcome such an
issue and provides a refrigeration cycle apparatus capable of
efficiently performing defrosting.
[0008] A refrigeration cycle apparatus according to an embodiment
of the present disclosure includes a compressor configured to
compress and discharge refrigerant; an expansion valve configured
to reduce pressure of the refrigerant to cause the refrigerant to
expand; a load side heat exchanger connected to the expansion
valve; a flow switching device connected to the compressor and the
load-side heat exchanger; a heat source side heat exchanger
including a first heat source side heat exchanger and a second heat
source side heat exchanger connected in parallel between the flow
switching device and the expansion valve; an opening-and-closing
valve provided on downstream of the second heat source side heat
exchanger through which the refrigerant flows during a defrosting
operation; and a controller configured to, when the defrosting
operation is performed, control the flow switching device so that
the refrigerant discharged from the compressor flows into the heat
source side heat exchanger. The controller includes a first
defrosting unit configured to switch the opening-and-closing valve
from an open state to a closed state when the defrosting operation
is started, a determination unit configured to determine a point in
time when defrosting targets to be defrosted are switched, and a
second defrosting unit configured to switch the opening-and-closing
valve from the closed state to the open state in accordance with
the point in time determined by the determination unit.
[0009] In the embodiment of the present disclosure, the first
defrosting unit closes the opening-and-closing valve when
defrosting is started, and thus the refrigerant discharged from the
compressor flows intensively to the first heat source side heat
exchanger of two heat source side heat exchangers. Subsequently,
when the second defrosting unit opens the opening-and-closing
valve, most of the heat of the refrigerant is consumed to defrost
the second heat source side heat exchanger. Thus, the heat of the
refrigerant is kept from being uselessly consumed in comparison
with a case where two heat source side heat exchangers connected in
series are simultaneously defrosted. Consequently, the two heat
source side heat exchangers can be efficiently defrosted.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus according
to Embodiment 1.
[0011] FIG. 2 is a functional block diagram illustrating an example
configuration of a controller illustrated in FIG. 1.
[0012] FIG. 3 is a hardware configuration diagram illustrating an
example configuration of the controller illustrated in FIG. 2.
[0013] FIG. 4 is a hardware configuration diagram illustrating
another example configuration of the controller illustrated in FIG.
2.
[0014] FIG. 5 is a flowchart illustrating an example of an
operation procedure performed by the refrigeration cycle apparatus
illustrated in FIG. 1.
[0015] FIG. 6 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus in
Modification 1.
[0016] FIG. 7 is a functional block diagram illustrating an example
configuration of the controller in Modification 1.
[0017] FIG. 8 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus in
Modification 2.
[0018] FIG. 9 is a functional block diagram illustrating an example
configuration of the controller in Modification 2.
[0019] FIG. 10 is a flowchart illustrating an example of an
operation procedure performed by the refrigeration cycle apparatus
illustrated in FIG. 8.
[0020] FIG. 11 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus in
Modification 3.
[0021] FIG. 12 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus according
to Embodiment 2.
[0022] FIG. 13 is a side view illustrating an example configuration
of a first heat source side heat exchanger illustrated in FIG.
12.
[0023] FIG. 14 is a side view illustrating an example configuration
of a second heat source side heat exchanger illustrated in FIG.
12.
[0024] FIG. 15 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus in a
comparative example.
[0025] FIG. 16 is a flowchart illustrating an example of an
operation procedure performed by the refrigeration cycle apparatus
in the comparative example illustrated in FIG. 15.
[0026] FIG. 17 includes graphs illustrating an example of the
relationship between a refrigerant flow rate and a position of a
heat source side heat exchanger during a defrosting operation.
[0027] FIG. 18 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus according
to Embodiment 3.
[0028] FIG. 19 is an external perspective view illustrating an
example configuration of a heat source side unit illustrated in
FIG. 18.
[0029] FIG. 20 is an external perspective view of the heat source
side unit illustrated in FIG. 18 as seen from a direction different
from that in FIG. 19.
[0030] FIG. 21 is a schematic view illustrating the layout of heat
source side heat exchangers in the heat source side unit
illustrated in FIG. 20 as seen from above.
[0031] FIG. 22 is a side view illustrating an example configuration
of a first division heat exchanger illustrated in FIG. 19.
[0032] FIG. 23 is a side view illustrating an example configuration
of the second heat source side heat exchanger illustrated in FIG.
20.
[0033] FIG. 24 is a refrigerant circuit diagram illustrating an
example configuration of a refrigeration cycle apparatus in
Modification 4.
DETAILED DESCRIPTION
Embodiment 1
[0034] A configuration of a refrigeration cycle apparatus in
Embodiment 1 will be described. FIG. 1 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus according to Embodiment 1. As illustrated in FIG.
1, a refrigeration cycle apparatus 1 includes a heat source side
unit 10, load side units 20a and 20b, and a controller 30 that
controls refrigerant devices included in the heat source side unit
10 and the load side units 20a and 20b. Although FIG. 1 illustrates
the case where the refrigeration cycle apparatus 1 includes two
load side units that are the load side units 20a and 20b, the
number of load side units may be one or may be three or more.
[0035] The heat source side unit 10 includes a compressor 2 that
compresses and discharges refrigerant, a heat source side heat
exchanger 15 that causes the refrigerant to exchange heat with
outside air, a flow switching device 5, an accumulator 6, and an
opening-and-closing valve 7. The heat source side heat exchanger 15
includes a first heat source side heat exchanger 3 and a second
heat source side heat exchanger 4. The load side unit 20a includes
a load side heat exchanger 21a that causes the refrigerant to
exchange heat with air in a room where the load side unit 20a is
installed, and an expansion valve 22a that reduces the pressure of
the refrigerant to cause the refrigerant to expand. The load side
unit 20b includes a load side heat exchanger 21b that causes the
refrigerant to exchange heat with air in a room where the load side
unit 20b is installed, and an expansion valve 22b that reduces the
pressure of the refrigerant to cause the refrigerant to expand.
[0036] The first heat source side heat exchanger 3 and the second
heat source side heat exchanger 4 are connected in parallel between
the flow switching device 5 and the expansion valves 22a and 22b.
Of two refrigerant inlet/outlet ports of the first heat source side
heat exchanger 3, one refrigerant inlet/outlet port is connected to
a first gas pipe 43a, and the other refrigerant inlet/outlet port
is connected to a first liquid pipe 44a. Of two refrigerant
inlet/outlet ports of the second heat source side heat exchanger 4,
one refrigerant inlet/outlet port is connected to a second gas pipe
43b, and the other refrigerant inlet/outlet port is connected to a
second liquid pipe 44b. The first gas pipe 43a and the second gas
pipe 43b are joined to a gas pipe 41 and communicate with the flow
switching device 5. The first liquid pipe 44a and the second liquid
pipe 44b are joined to a liquid pipe 47 and communicate with the
expansion valves 22a and 22b. The opening-and-closing valve 7 is
provided in the second liquid pipe 44b.
[0037] The flow switching device 5 is connected to the load side
heat exchangers 21a and 21b via a refrigerant pipe 42 and is
connected to the accumulator 6 via a refrigerant pipe 48.
Furthermore, the flow switching device 5 is connected to the
compressor 2 and the accumulator 6 via a refrigerant pipe 49. The
accumulator 6 is connected to a refrigerant inlet of the compressor
2. The compressor 2, the first heat source side heat exchanger 3
and the second heat source side heat exchanger 4, the expansion
valve 22a, and the load side heat exchanger 21a are connected with
pipes, such as the refrigerant pipe 42, to form a refrigerant
circuit 60a. Furthermore, the compressor 2, the first heat source
side heat exchanger 3 and the second heat source side heat
exchanger 4, the expansion valve 22b, and the load side heat
exchanger 21b are connected with pipes, such as the refrigerant
pipe 42, to form a refrigerant circuit 60b.
[0038] In the second heat source side heat exchanger 4, a heat
exchanger temperature sensor 11 is provided that detects a
temperature Te of refrigerant. In the second liquid pipe 44b, a
refrigerant temperature sensor 12 is provided that detects a
temperature Tn2 of refrigerant that flows through the second liquid
pipe 44b. In the load side unit 20a, a room temperature sensor 23a
is provided that detects a temperature of air in the room where the
load side unit 20a is installed. In the load side unit 20b, a room
temperature sensor 23b is provided that detects a temperature of
air in the room where the load side unit 20b is installed. The heat
exchanger temperature sensor 11, the refrigerant temperature sensor
12, and the room temperature sensors 23a and 23b are, for example,
thermistors. The heat exchanger temperature sensor 11 may be
provided on a first heat source side heat exchanger 3 side in place
of the second heat source side heat exchanger 4.
[0039] The compressor 2 is a compressor whose displacement is
variable, for example, an inverter compressor. The accumulator 6 is
a container that keeps liquid refrigerant from being sucked into
the compressor 2. The expansion valves 22a and 22b are, for
example, electronic expansion valves. The flow switching device 5
switches, to the gas pipe 41 or the refrigerant pipe 42, a
direction in which the refrigerant discharged from the compressor 2
flows. The flow switching device 5 is, for example, a four-way
valve. The opening-and-closing valve 7 is, for example, a shutoff
valve whose state can be switched, of a closed state and an open
state, from one state to the other state. The opening-and-closing
valve 7 may be an electronic expansion valve that adjusts a flow
rate of refrigerant that circulates. The first heat source side
heat exchanger 3 and the second heat source side heat exchanger 4,
and the load side heat exchangers 21a and 21b are, for example,
fin-and-tube heat exchangers.
[0040] The controller 30 is connected to, via a signal line not
illustrated in the figure, devices that are the compressor 2, the
flow switching device 5, the expansion valves 22a and 22b, and the
opening-and-closing valve 7. Furthermore, the controller 30 is
connected to, via a signal line not illustrated in the figure,
sensors that are the room temperature sensors 23a and 23b, the heat
exchanger temperature sensor 11, and the refrigerant temperature
sensor 12. Communication connections of the controller 30 to the
devices that are the compressor 2, the flow switching device 5, the
expansion valve 22a, the expansion valve 22b, and the
opening-and-closing valve 7 may be established not only by wire but
also wirelessly. Regarding the sensors as well, communication
connections of the controller 30 to the sensors that are the room
temperature sensor 23a, the room temperature sensor 23b, the heat
exchanger temperature sensor 11, and the refrigerant temperature
sensor 12 may be established not only by wire but also
wirelessly.
[0041] Before a configuration of the controller 30 illustrated in
FIG. 1 will be described, the flow of refrigerant in each of
operation modes of the refrigeration cycle apparatus 1 will be
simply described. Here, the case of the refrigerant circuit 60a
will be described. Furthermore, assume that the opening-and-closing
valve 7 is in an open state.
[Cooling Operation]
[0042] First, the flow of refrigerant in the case where the
refrigeration cycle apparatus 1 performs a cooling operation will
be described with reference to FIG. 1. In the case where the
refrigeration cycle apparatus 1 performs the cooling operation, the
controller 30 switches between flow passages of the flow switching
device 5 so that refrigerant discharged from the compressor 2 flows
into the first heat source side heat exchanger 3 and the second
heat source side heat exchanger 4. When low-temperature,
low-pressure refrigerant is compressed by the compressor 2,
high-temperature, high-pressure gaseous refrigerant is discharged
from the compressor 2. The gaseous refrigerant discharged from the
compressor 2 flows through the flow switching device 5 and flows
into the first heat source side heat exchanger 3 and the second
heat source side heat exchanger 4. The refrigerant having flowed
into the first heat source side heat exchanger 3 and the second
heat source side heat exchanger 4 is condensed into
low-temperature, high-pressure liquid refrigerant by exchanging
heat with air in these heat exchangers connected in parallel and
flows out of the first heat source side heat exchanger 3 and the
second heat source side heat exchanger 4.
[0043] The liquid refrigerant having flowed out of the first heat
source side heat exchanger 3 and the second heat source side heat
exchanger 4 is caused to turn into low-temperature, low-pressure
liquid refrigerant by the expansion valve 22a. The liquid
refrigerant flows into the load side heat exchanger 21a. The
refrigerant having flowed into the load side heat exchanger 21a
evaporates into low-temperature, low-pressure gaseous refrigerant
by exchanging heat with air in the load side heat exchanger 21a and
flows out of the load side heat exchanger 21a. In the load side
heat exchanger 21a, when the refrigerant receives heat from air in
the room, the air in the room is cooled. The refrigerant having
flowed out of the load side heat exchanger 21a is sucked into the
compressor 2 via the flow switching device 5. During the cooling
operation, a cycle is repeated in which the refrigerant discharged
from the compressor 2 flows through the first heat source side heat
exchanger 3 and the second heat source side heat exchanger 4, the
expansion valve 22a, and the load side heat exchanger 21a in
sequence and then is sucked into the compressor 2.
[Heating Operation]
[0044] Next, the flow of refrigerant in the case where the
refrigeration cycle apparatus 1 performs a heating operation will
be described with reference to FIG. 1. In the case where the
refrigeration cycle apparatus 1 performs the heating operation, the
controller 30 switches between the flow passages of the flow
switching device 5 so that refrigerant discharged from the
compressor 2 flows into the load side heat exchanger 21a. When
low-temperature, low-pressure refrigerant is compressed by the
compressor 2, high-temperature, high-pressure gaseous refrigerant
is discharged from the compressor 2. The high-temperature,
high-pressure gaseous refrigerant discharged from the compressor 2
flows through the flow switching device 5 and flows into the load
side heat exchanger 21a. The refrigerant having flowed into the
load side heat exchanger 21a is condensed into high-temperature,
high-pressure liquid refrigerant by exchanging heat with air in the
load side heat exchanger 21a and flows out of the load side heat
exchanger 21a. In the load side heat exchanger 21a, when the
refrigerant transfers heat to air in the room, the air in the room
is heated.
[0045] The high-temperature, high-pressure liquid refrigerant
having flowed out of the load side heat exchanger 21a is caused to
turn into low-temperature, low-pressure liquid refrigerant by the
expansion valve 22a. The liquid refrigerant flows into the first
heat source side heat exchanger 3 and the second heat source side
heat exchanger 4. In the first heat source side heat exchanger 3
and the second heat source side heat exchanger 4, the refrigerant
evaporates into low-temperature, low-pressure gaseous refrigerant
by exchanging heat with air and flows out of the first heat source
side heat exchanger 3 and the second heat source side heat
exchanger 4. The refrigerant having flowed out of the first heat
source side heat exchanger 3 and the second heat source side heat
exchanger 4 is sucked into the compressor 2 via the flow switching
device 5. While the refrigeration cycle apparatus 1 is performing
the heating operation, a cycle is repeated in which the refrigerant
discharged from the compressor 2 flows through the load side heat
exchanger 21a, the expansion valve 22a, and the first heat source
side heat exchanger 3 and the second heat source side heat
exchanger 4 in sequence and then is sucked into the compressor
2.
[Defrosting Operation]
[0046] The flow of refrigerant in the case where the refrigeration
cycle apparatus 1 performs a defrosting operation will be described
with reference to FIG. 1. In the case where the refrigeration cycle
apparatus 1 switches an operation mode from the heating operation
to the defrosting operation, the controller 30 switches between the
flow passages of the flow switching device 5 so that refrigerant
discharged from the compressor 2 flows into the first heat source
side heat exchanger 3 and the second heat source side heat
exchanger 4. Furthermore, the controller 30 performs control to put
the expansion valve 22a in a fully open state. In the case of the
defrosting operation, a direction in which refrigerant in the
refrigerant circuit 60a flows is the same as that in the cooling
operation, and thus a detailed description of the flow of the
refrigerant is omitted.
[0047] Next, a configuration of the controller 30 illustrated in
FIG. 1 will be described. FIG. 2 is a functional block diagram
illustrating an example configuration of the controller illustrated
in FIG. 1.
[0048] The controller 30 includes a refrigeration cycle control
unit 51, a determination unit 52, a timer 53, a first defrosting
unit 54, and a second defrosting unit 55. Regarding the controller
30, various functions are implemented by an arithmetic unit, such
as a microcomputer, executing software. Furthermore, the controller
30 may be constituted by hardware, such as a circuit device, that
implements various functions. A set temperature Ts1 is input to the
controller 30 via a remote controller not illustrated in the figure
by a user that uses the load side unit 20a. A set temperature Ts2
is input to the controller 30 via a remote controller not
illustrated in the figure by a user that uses the load side unit
20b. Incidentally, in the refrigeration cycle apparatus 1
illustrated in FIG. 1, a location where the controller 30 is
installed is not limited to the illustrated location, and the
controller 30 may be provided in the heat source side unit 10, or
may be provided in the load side unit 20a or 20b.
[0049] The refrigeration cycle control unit 51 controls the flow
switching device 5 in accordance with an operation mode of the
refrigeration cycle apparatus 1. The refrigeration cycle control
unit 51 controls an operating frequency of the compressor 2 and
opening degrees of the expansion valves 22a and 22b by using
detected values received from the room temperature sensors 23a and
23b and the set temperatures Ts1 and Ts2. Specifically, the
refrigeration cycle control unit 51 controls the operating
frequency of the compressor 2 and the opening degrees of the
expansion valves 22a and 22b so that the detected value of the room
temperature sensor 23a approaches the set temperature Ts1 and the
detected value of the room temperature sensor 23b approaches the
set temperature Ts2.
[0050] While the refrigeration cycle apparatus 1 is performing the
heating operation, the refrigeration cycle control unit 51 monitors
the temperature Te of refrigerant received from the heat exchanger
temperature sensor 11 and determines whether or not the temperature
Te of refrigerant is not more than a predetermined temperature
threshold T0. The temperature threshold T0 is, for example, 0
degrees C. When the temperature Te of refrigerant reaches not more
than the temperature threshold T0, the refrigeration cycle control
unit 51 controls the flow switching device 5 to switch between the
flow passages and also transmits, to the determination unit 52,
defrosting start information representing that the defrosting
operation has been started. When the refrigeration cycle control
unit 51 receives defrosting completion information from the
determination unit 52, the refrigeration cycle control unit 51
controls the flow switching device 5 to switch between the flow
passages and switches the operation mode from the defrosting
operation to the heating operation.
[0051] The timer 53 measures a time period and provides measurement
time information to the determination unit 52. The determination
unit 52 determines, in accordance with at least either a time
period that has elapsed since the start of defrosting or the
temperature Tn2 of refrigerant detected by the refrigerant
temperature sensor 12, a point in time when defrosting targets to
be defrosted are switched. When the determination unit 52 receives
the defrosting start information from the refrigeration cycle
control unit 51, the determination unit 52 transfers the defrosting
start information to the first defrosting unit 54 and also monitors
a time t1 representing a time period that has elapsed since the
start of defrosting. The determination unit 52 determines whether
or not the time t1 is not less than a predetermined time threshold
tth1. The time threshold tth1 is set to a time before defrosting of
the first heat source side heat exchanger 3 is completely finished.
When the time t1 reaches not less than the time threshold tth1, the
determination unit 52 transmits, to the second defrosting unit 55,
switching instruction information representing an instruction for
switching between states of the opening-and-closing valve 7.
[0052] Furthermore, after the determination unit 52 transmits the
switching instruction information to the second defrosting unit 55,
the determination unit 52 monitors the temperature Tn2 of
refrigerant received from the refrigerant temperature sensor 12 and
determines whether or not the temperature Tn2 of refrigerant is not
less than a predetermined temperature threshold Tb. The temperature
threshold Tb is, for example, 7 degrees C. When the temperature Tn2
of refrigerant reaches not less than the temperature threshold Tb,
the determination unit 52 transmits, to the refrigeration cycle
control unit 51, defrosting completion information representing
that defrosting has been completed.
[0053] When the first defrosting unit 54 receives the defrosting
start information from the determination unit 52, the first
defrosting unit 54 switches the opening-and-closing valve 7 from an
open state to a closed state. When the second defrosting unit 55
receives the switching instruction information from the
determination unit 52, the second defrosting unit 55 switches the
opening-and-closing valve 7 from the closed state to the open
state.
[0054] Here, an example of hardware of the controller 30
illustrated in FIG. 2 will be described. FIG. 3 is a hardware
configuration diagram illustrating an example configuration of the
controller illustrated in FIG. 2. In the case where various
functions of the controller 30 are executed by hardware, the
controller 30 illustrated in FIG. 2 is constituted by a processing
circuit 31 as illustrated in FIG. 3. Functions of the refrigeration
cycle control unit 51, the determination unit 52, the timer 53, the
first defrosting unit 54, and the second defrosting unit 55 that
are illustrated in FIG. 2 are implemented by the processing circuit
31.
[0055] In the case where each function is executed by hardware, the
processing circuit 31 corresponds, for example, to a single
circuit, a complex circuit, a programmed processor, a parallel
programmed processor, an Application Specific Integrated Circuit
(ASIC), a Field-Programmable Gate Array (FPGA), or a combination of
these. Functions of units that are the refrigeration cycle control
unit 51, the determination unit 52, the timer 53, the first
defrosting unit 54, and the second defrosting unit 55 may be
implemented by respective processing circuits 31, or the functions
of the units may be implemented by one processing circuit 31.
[0056] Furthermore, an example of other hardware of the controller
30 illustrated in FIG. 2 will be described. FIG. 4 is a hardware
configuration diagram illustrating another example configuration of
the controller illustrated in FIG. 2. In the case where various
functions of the controller 30 are executed by software, the
controller 30 illustrated in FIG. 2 is constituted by a processor
71 and a memory 72 as illustrated in FIG. 4. Functions of the
refrigeration cycle control unit 51, the determination unit 52, the
timer 53, the first defrosting unit 54, and the second defrosting
unit 55 are implemented by the processor 71 and the memory 72. FIG.
4 illustrates that the processor 71 and the memory 72 are connected
to each other in such a manner that they can communicate with each
other.
[0057] In the case where each function is executed by software, the
functions of the refrigeration cycle control unit 51, the
determination unit 52, the timer 53, the first defrosting unit 54,
and the second defrosting unit 55 are implemented by software,
firmware, or a combination of software and firmware. Software and
firmware are written as programs and stored in the memory 72. The
processor 71 reads out a program stored in the memory 72 and
executes the program to thereby implement a function of each
unit.
[0058] As the memory 72, for example, non-volatile semiconductor
memories, such as a Read Only Memory (ROM), a flash memory, an
Erasable and Programmable ROM (EPROM), and an Electrically Erasable
and Programmable ROM (EEPROM), are used. Furthermore, as the memory
72, a volatile semiconductor memory, such as a Random Access Memory
(RAM), may be used. Additionally, as the memory 72, detachable
recording media, such as a magnetic disk, a flexible disk, an
optical disc, a Compact Disc (CD), a Mini Disc (MD), and a Digital
Versatile Disc (DVD), may be used.
[0059] Next, the operation of the refrigeration cycle apparatus 1
in Embodiment 1 will be described. FIG. 5 is a flowchart
illustrating an example of an operation procedure performed by the
refrigeration cycle apparatus illustrated in FIG. 1. FIG. 5
illustrates an example of an operation procedure in the case where
the refrigeration cycle apparatus 1 performs the defrosting
operation. Assume that the refrigeration cycle apparatus 1 is
performing the heating operation before starting the operation
procedure illustrated in FIG. 5 and the opening-and-closing valve 7
is in an open state.
[0060] The refrigeration cycle control unit 51 determines whether
or not the temperature Te of refrigerant received from the heat
exchanger temperature sensor 11 has reached not more than the
temperature threshold T0 (step S101). When the temperature Te of
refrigerant reaches not more than the temperature threshold T0 in
step S101, the refrigeration cycle control unit 51 determines that
frost has adhered to the heat source side heat exchanger 15 and
controls the flow switching device 5 to switch between the flow
passages (step S102). Thus, the refrigerant discharged from the
compressor 2 flows through the flow switching device 5 and flows
into the heat source side heat exchanger 15. Furthermore, the
refrigeration cycle control unit 51 transmits defrosting start
information to the determination unit 52 in step S102.
[0061] When the determination unit 52 receives the defrosting start
information from the refrigeration cycle control unit 51, the
determination unit 52 transfers the defrosting start information to
the first defrosting unit 54 and also monitors the time t1 measured
by the timer 53. When the first defrosting unit 54 receives the
defrosting start information from the determination unit 52, the
first defrosting unit 54 closes the opening-and-closing valve 7
(step S103). The determination unit 52 determines whether or not
the time t1 has reached not less than the time threshold tth1 (step
S104). When the time t1 reaches not less than the time threshold
tth1 in step S104, the determination unit 52 transmits switching
instruction information to the second defrosting unit 55.
[0062] When the second defrosting unit 55 receives the switching
instruction information from the determination unit 52, the second
defrosting unit 55 opens the opening-and-closing valve 7 (step
S105). After the determination unit 52 transmits the switching
instruction information to the second defrosting unit 55, the
determination unit 52 determines whether or not the temperature Tn2
of refrigerant received from the refrigerant temperature sensor 12
has reached not less than the temperature threshold Tb (step S106).
When the temperature Tn2 of refrigerant reaches not less than the
temperature threshold Tb, the determination unit 52 determines that
defrosting of the heat source side heat exchanger 15 has been
completed and transmits defrosting completion information to the
refrigeration cycle control unit 51.
[0063] When the refrigeration cycle control unit 51 receives the
defrosting completion information from the determination unit 52,
the refrigeration cycle control unit 51 controls the flow switching
device 5 to switch between the flow passages (step S107). Thus, the
refrigerant discharged from the compressor 2 flows through the flow
switching device 5 and flows into the load side units 20a and 20b.
The operation mode of the refrigeration cycle apparatus 1 returns
from the defrosting operation to the heating operation.
[0064] Thus, the first heat source side heat exchanger 3 is
intensively defrosted from the time when the refrigeration cycle
apparatus 1 starts defrosting until the time when the time t1
reaches the time threshold tth1. Then, the refrigeration cycle
apparatus 1 starts to defrost the second heat source side heat
exchanger 4 before defrosting of the first heat source side heat
exchanger 3 is completed, and the flow of refrigerant to the first
heat source side heat exchanger 3 is continued. Subsequently, the
determination unit 52 determines, in accordance with a temperature
Tn2 of refrigerant downstream of the second heat source side heat
exchanger 4, whether or not defrosting of the second heat source
side heat exchanger 4 has been completed. When it is determined, in
accordance with the temperature of refrigerant downstream of the
second heat source side heat exchanger 4, that defrosting of the
second heat source side heat exchanger has been completed,
defrosting of the first heat source side heat exchanger 3 has been
also completed.
[0065] Incidentally, in the example configuration illustrated in
FIG. 1, although the refrigerant temperature sensor 12 is provided
in the second liquid pipe 44b, the refrigerant temperature sensor
12 may be provided in the liquid pipe 47 near the confluence of the
first liquid pipe 44a and the second liquid pipe 44b. In this case,
in step S104 illustrated in FIG. 5, the determination unit 52
determines whether or not the temperature Tn2 of refrigerant is not
less than a predetermined temperature threshold Ta. As a result of
a determination made in step S104, when the temperature Tn2 of
refrigerant is not less than the temperature threshold Ta, the
determination unit 52 only has to transmit the switching
instruction information to the second defrosting unit 55. The
relationship between the temperature thresholds Ta and Tb is, for
example, Ta>Tb. Even when the refrigeration cycle apparatus 1
proceeds to the operation of step S105 owing to the relationship of
Ta>Tb before defrosting of the first heat source side heat
exchanger 3 is completely finished, the refrigerant also flows
through the first heat source side heat exchanger 3, and thus the
defrosting is performed. Furthermore, when the refrigerant
temperature sensor 12 is provided in the liquid pipe 47, the timer
53 does not have to be provided in the controller 30.
[0066] The refrigeration cycle apparatus 1 in Embodiment 1 includes
the compressor 2, the expansion valve 22a, the load side heat
exchanger 21a, the flow switching device 5, the heat source side
heat exchanger 15, the opening-and-closing valve 7, and the
controller 30. The heat source side heat exchanger 15 includes the
first heat source side heat exchanger 3 and the second heat source
side heat exchanger 4 connected in parallel between the flow
switching device 5 and the expansion valve 22a. The
opening-and-closing valve 7 is provided on downstream of the second
heat source side heat exchanger 4 through which refrigerant flows
during the defrosting operation. When the defrosting operation is
performed, the controller 30 controls the flow switching device 5
so that the refrigerant discharged from the compressor 2 flows into
the heat source side heat exchanger 15. The controller 30 includes
the first defrosting unit 54, the determination unit 52, and the
second defrosting unit 55. When the defrosting operation is
started, the first defrosting unit 54 switches the
opening-and-closing valve 7 from an open state to a closed state.
The determination unit 52 determines a point in time when
defrosting targets to be defrosted are switched. The second
defrosting unit switches the opening-and-closing valve 7 from the
closed state to the open state in accordance with the point in time
determined by the determination unit 52.
[0067] In Embodiment 1, the first defrosting unit 54 closes the
opening-and-closing valve 7 when defrosting is started, and thus
the refrigerant discharged from the compressor 2 flows intensively
to the first heat source side heat exchanger 3 of two heat source
side heat exchangers. Subsequently, the second defrosting unit 55
opens the opening-and-closing valve 7. Thus, the refrigerant flows
to the second heat source side heat exchanger 4 and also flows to
the first heat source side heat exchanger 3. When the refrigerant
flows to the two heat source side heat exchangers, most of the heat
of the refrigerant is consumed in the second heat source side heat
exchanger 4, and also frost remaining in the first heat source side
heat exchanger 3 melts. Thus, the heat of the refrigerant is kept
from being uselessly consumed in comparison with a case where two
heat source side heat exchangers connected in series are
simultaneously defrosted. Consequently, the two heat source side
heat exchangers can be efficiently defrosted.
(Modification 1)
[0068] Modification 1 is the case where the refrigerant temperature
sensor 12 is not provided in the refrigeration cycle apparatus 1
illustrated in FIG. 1. In Modification 1, components that are the
same as components described with reference to FIGS. 1 to 5 are
denoted by the same reference signs, and a detailed description
thereof is omitted.
[0069] A configuration of a refrigeration cycle apparatus in
Modification 1 will be described. FIG. 6 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus in Modification 1. FIG. 7 is a functional block
diagram illustrating an example configuration of the controller in
Modification 1.
[0070] In a heat source side unit 10a in a refrigeration cycle
apparatus 1a, the refrigerant temperature sensor 12 illustrated in
FIG. 1 is not provided. After the determination unit 52 transmits
the switching instruction information to the second defrosting unit
55, the determination unit 52 determines whether or not the time t1
measured by the timer 53 is not less than a predetermined time
threshold tth2. The relationship between the time thresholds tth1
and tth2 is tth1<tth2. When the time t1 reaches not less than
the time threshold tth2, the determination unit 52 transmits the
defrosting completion information to the refrigeration cycle
control unit 51.
[0071] The operation of the refrigeration cycle apparatus 1a in
Modification 1 will be described with reference to FIG. 5. Here, an
operation different from the operations illustrated in FIG. 5 will
be described, and a detailed description of operations similar to
the operations described with reference to FIG. 5 is omitted.
[0072] In step S106, the determination unit 52 determines whether
or not the time t1 measured by the timer 53 has reached not less
than the time threshold tth2. As a result of a determination made
in step S106, when the time t1 reaches not less than the time
threshold tth2, the determination unit 52 transmits the defrosting
completion information to the refrigeration cycle control unit
51.
[0073] In Modification 1, even when the refrigerant temperature
sensor 12 is not provided, effects of Embodiment 1 can be
obtained.
(Modification 2)
[0074] Modification 2 is the case where a flow control valve and a
refrigerant temperature sensor are provided in the first liquid
pipe 44a in the refrigeration cycle apparatus 1 illustrated in FIG.
1. In Modification 2, components that are the same as components
described with reference to FIGS. 1 to 7 are denoted by the same
reference signs, and a detailed description thereof is omitted.
[0075] A configuration of a refrigeration cycle apparatus in
Modification 2 will be described. FIG. 8 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus in Modification 2. FIG. 9 is a functional block
diagram illustrating an example configuration of the controller in
Modification 2. As illustrated in FIG. 8, in the first liquid pipe
44a in a heat source side unit 10b in a refrigeration cycle
apparatus 1b, a refrigerant temperature sensor 12a and a flow
control valve 9 are provided. The refrigerant temperature sensor
12a detects a temperature Tn1 of refrigerant that flows through the
first liquid pipe 44a. The flow control valve 9 can be switched, of
a closed state and an open state, from one state to the other
state.
[0076] Furthermore, the flow control valve 9 can adjust a flow rate
of refrigerant that circulates by changing its opening degree. As
illustrated in FIG. 9, the controller 30 in Modification 2 does not
include the timer 53 illustrated in FIG. 2. Regarding the
temperature Tn1 of refrigerant, the controller 30 stores, in
advance, the temperature threshold Ta as a criterion value for
determining a point in time when defrosting targets to be defrosted
are switched. Values of Ta and Tb may be the same or may be
different.
[0077] Next, the operation of the refrigeration cycle apparatus 1b
in Modification 2 will be described. FIG. 10 is a flowchart
illustrating an example of an operation procedure performed by the
refrigeration cycle apparatus illustrated in FIG. 8. Assume that
the refrigeration cycle apparatus 1b is performing the heating
operation before starting the operation procedure illustrated in
FIG. 10 and the flow control valve 9 and the opening-and-closing
valve 7 are in an open state. Operations of steps S201 and S202
illustrated in FIG. 10 are similar to the operations of steps S101
and S102 described with reference to FIG. 5, and thus a detailed
description thereof is omitted.
[0078] After a determination is made in step S201, when the
determination unit 52 receives defrosting start information from
the refrigeration cycle control unit 51, the determination unit 52
transfers the defrosting start information to the first defrosting
unit 54 and also monitors the temperature Tn1 of refrigerant
detected by the refrigerant temperature sensor 12a. When the first
defrosting unit 54 receives the defrosting start information from
the determination unit 52, the first defrosting unit 54 closes the
opening-and-closing valve 7 (step S203). The determination unit 52
determines whether or not the temperature Tn1 of refrigerant has
reached not less than the temperature threshold Ta (step S204).
When the temperature Tn1 of refrigerant reaches not less than the
temperature threshold Ta in step S204, the determination unit 52
transmits switching instruction information to the second
defrosting unit 55.
[0079] When the second defrosting unit 55 receives the switching
instruction information from the determination unit 52, the second
defrosting unit 55 opens the opening-and-closing valve 7 (step
S205) and closes the flow control valve 9 (step S206). After the
determination unit 52 transmits the switching instruction
information to the second defrosting unit 55, the determination
unit 52 determines whether or not the temperature Tn2 of
refrigerant detected by a refrigerant temperature sensor 12b has
reached not less than the temperature threshold Tb (step S207).
When the temperature Tn2 of refrigerant reaches not less than the
temperature threshold Tb, the determination unit 52 determines that
defrosting of the heat source side heat exchanger 15 has been
completed and transmits defrosting completion information to the
second defrosting unit 55 and the refrigeration cycle control unit
51.
[0080] When the second defrosting unit 55 receives the defrosting
completion information from the determination unit 52, the second
defrosting unit 55 opens the flow control valve 9 (step S208). When
the refrigeration cycle control unit 51 receives the defrosting
completion information from the determination unit 52, the
refrigeration cycle control unit 51 controls the flow switching
device 5 to switch between the flow passages (step S209). Thus, the
refrigerant discharged from the compressor 2 flows through the flow
switching device 5 and flows into the load side units 20a and 20b.
The operation mode of the refrigeration cycle apparatus 1 returns
from the defrosting operation to the heating operation.
[0081] Incidentally, in step S206 illustrated in FIG. 10, although
the second defrosting unit 55 closes the flow control valve 9, the
second defrosting unit 55 does not completely close the flow
control valve 9 and may reduce the opening degree of the flow
control valve 9 to cause a little refrigerant to circulate. In this
case, in step S208, the second defrosting unit 55 opens the flow
control valve 9 fully.
[0082] In Modification 2, valves that shut off flows of refrigerant
are provided in the respective liquid pipes of the first heat
source side heat exchanger 3 and the second heat source side heat
exchanger 4 that are connected in parallel. In the defrosting
operation, the refrigeration cycle apparatus 1b in Modification 2
performs opening and closing control of each valve to first
intensively defrost the first heat source side heat exchanger 3 and
then to intensively defrost the other second heat source side heat
exchanger 4, and thus defrosting can be performed reliably and
efficiently.
[0083] Furthermore, the determination unit 52 determines, by using
the temperature Tn1 of refrigerant, a point in time when an object
to be mainly defrosted is switched from the first heat source side
heat exchanger 3 to the second heat source side heat exchanger 4.
For this reason, the determination unit 52 can determine whether or
not frost has remained in the first heat source side heat exchanger
3 more accurately than by using the time t1 measured by the timer
53. Furthermore, in Modification 2, the timer 53 does not have to
be provided in the controller 30.
(Modification 3)
[0084] Modification 3 is the case where three or more heat source
side heat exchangers are connected in parallel in the refrigeration
cycle apparatus 1 illustrated in FIG. 1. In Modification 3,
components that are the same as components described with reference
to FIGS. 1 to 10 are denoted by the same reference signs, and a
detailed description thereof is omitted.
[0085] A configuration of a refrigeration cycle apparatus in
Modification 2 will be described. FIG. 11 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus in Modification 3. As illustrated in FIG. 11, in a
heat source side unit 10c in a refrigeration cycle apparatus 1c, a
third heat source side heat exchanger 8 connected in parallel with
the first heat source side heat exchanger 3 and the second heat
source side heat exchanger 4 is provided. The third heat source
side heat exchanger 8 is connected to the gas pipe 41 via a third
gas pipe 43c and is connected to the liquid pipe 47 via a third
liquid pipe 44c.
[0086] In the third liquid pipe 44c, a refrigerant temperature
sensor 12c and a second flow control valve 9b are provided. The
refrigerant temperature sensor 12c detects a temperature Tn3 of
refrigerant that flows through the third liquid pipe 44c. The
determination unit 52 compares the temperature Tn3 of refrigerant
with a predetermined temperature threshold Td and switches between
defrosting targets to be defrosted when the temperature Tn3 of
refrigerant reaches not less than the temperature threshold Td.
Incidentally, configurations of a first flow control valve 9a and
the second flow control valve 9b are similar to the configuration
of the flow control valve 9, a configuration of the refrigerant
temperature sensor 12c is similar to the configuration of the
refrigerant temperature sensor 12, and thus a detailed description
of these is omitted.
[0087] The operation of the refrigeration cycle apparatus 1c in
Modification 2 will be described with reference to FIG. 10. Here,
an operation different from the operations illustrated in FIG. 10
will be described, and a detailed description of operations similar
to the operations described with reference to FIG. 10 is omitted.
As a default state, the opening-and-closing valve 7, the first flow
control valve 9a, and the second flow control valve 9b are in an
open state.
[0088] In step S203, when the first defrosting unit 54 receives the
defrosting start information from the determination unit 52, the
first defrosting unit 54 maintains the first flow control valve 9a
in the open state and closes the opening-and-closing valve 7 and
the second flow control valve 9b. In step S206, the second
defrosting unit 55 closes the first flow control valve 9a. In step
S207, when the temperature Tn2 of refrigerant reaches not less than
the temperature threshold Tb, the determination unit 52 transmits
switching instruction information to the second defrosting unit 55.
When the second defrosting unit 55 receives the switching
instruction information from the determination unit 52 after step
S206, the second defrosting unit 55 closes the opening-and-closing
valve 7 and opens the second flow control valve 9b.
[0089] After the determination unit 52 transmits the switching
instruction information to the second defrosting unit 55 in
accordance with a result of a determination made in step S207, the
determination unit 52 determines whether or not the temperature Tn3
of refrigerant detected by the refrigerant temperature sensor 12c
has reached not less than the temperature threshold Td. When the
temperature Tn3 of refrigerant reaches not less than the
temperature threshold Td, the determination unit 52 determines that
defrosting of the heat source side heat exchanger 15 has been
completed and transmits defrosting completion information to the
second defrosting unit 55 and the refrigeration cycle control unit
51. Subsequently, the controller 30 performs the operations of
steps S208 and S209.
[0090] Although FIG. 11 illustrates the case where three heat
source side heat exchangers are connected in parallel, the number
of heat source side heat exchangers connected in parallel may be
four or more. In this case, a flow control device and a refrigerant
temperature sensor are provided on a liquid pipe of each heat
source side heat exchanger. Furthermore, in the refrigeration cycle
apparatus 1c illustrated in FIG. 11, the determination unit 52 may
determine, in accordance with the time t1 measured by the timer 53
illustrated in FIG. 2, a point in time when defrosting targets to
be defrosted are switched. In this case, the refrigerant
temperature sensors 12a to 12c do not have to be provided.
[0091] In Modification 3, even when the number of heat source side
heat exchangers connected in parallel is three or more, defrosting
can be efficiently performed.
Embodiment 2
[0092] A refrigeration cycle apparatus in Embodiment 2 is a
refrigeration cycle apparatus in which a header is provided for a
heat source side heat exchanger, and the header splits refrigerant
that circulates into streams and merges streams of the refrigerant.
In Embodiment 2, components that are the same as components
described in Embodiment 1 are denoted by the same reference signs,
and a detailed description thereof is omitted.
[0093] A configuration of the refrigeration cycle apparatus in
Embodiment 2 will be described. FIG. 12 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus according to Embodiment 2. A refrigeration cycle
apparatus 1d includes a heat source side unit 10d. In the heat
source side unit 10d, a first gas header 61 is provided on a first
gas pipe 43a side of the first heat source side heat exchanger 3,
and a first liquid header 62 is provided on a first liquid pipe 44a
side of the first heat source side heat exchanger 3. Furthermore,
in the heat source side unit 10d, a second gas header 63 is
provided on a second gas pipe 43b side of the second heat source
side heat exchanger 4, and a second liquid header 64 is provided on
a second liquid pipe 44b side of the second heat source side heat
exchanger 4.
[0094] FIG. 13 is a side view illustrating an example configuration
of the first heat source side heat exchanger illustrated in FIG.
12. FIG. 14 is a side view illustrating an example configuration of
the second heat source side heat exchanger illustrated in FIG. 12.
For convenience of explanation, FIGS. 13 and 14 illustrate the X
axis and the Z axis to define directions. A direction opposite to a
Z-axis arrow illustrated in FIGS. 13 and 14 is a gravity direction.
Solid line arrows illustrated in FIGS. 13 and 14 represent
directions in which refrigerant flows when the refrigeration cycle
apparatus 1 performs the cooling operation and the defrosting
operation. Dashed line arrows illustrated in FIGS. 13 and 14
represent directions in which refrigerant flows when the
refrigeration cycle apparatus 1 performs the heating operation.
[0095] As illustrated in FIG. 13, the first heat source side heat
exchanger 3 includes a plurality of heat-transfer tubes 45a and a
plurality of heat-transfer fins 46a. The first gas pipe 43a is
connected to the first gas header 61. A position at which the first
gas pipe 43a is connected to the first gas header 61 is a middle
portion of the height that is the length of the first gas header 61
in a direction (Z-axis arrow direction) perpendicular to the
ground. The middle portion is not limited to the exact middle
position of the height of the first gas header 61 and includes a
certain range of heights based on the middle position. The first
liquid pipe 44a is connected to a lower portion of the first liquid
header 62. When the refrigeration cycle apparatus 1 performs the
cooling operation and the defrosting operation, the first gas
header 61 splits refrigerant flowing in from the first gas pipe 43a
into streams flowing through the plurality of heat-transfer tubes
45a. When the refrigeration cycle apparatus 1 performs the heating
operation, the first gas header 61 merges streams of refrigerant
flowing in from the plurality of heat-transfer tubes 45a and causes
the refrigerant to flow to the first gas pipe 43a.
[0096] As illustrated in FIG. 14, the second heat source side heat
exchanger 4 includes a plurality of heat-transfer tubes 45b and a
plurality of heat-transfer fins 46b. The second gas pipe 43b is
connected to the second gas header 63. A position at which the
second gas pipe 43b is connected to the second gas header 63 is a
middle portion of the height that is the length of the second gas
header 63 in a direction (Z-axis arrow direction) perpendicular to
the ground. The middle portion is not limited to the exact middle
position of the height of the second gas header 63 and includes a
certain range of heights based on the middle position. The second
liquid pipe 44b is connected to a lower portion of the second
liquid header 64. When the refrigeration cycle apparatus 1 performs
the cooling operation and the defrosting operation, the second gas
header 63 splits refrigerant flowing in from the second gas pipe
43b into streams flowing through the plurality of heat-transfer
tubes 45b. When the refrigeration cycle apparatus 1 performs the
heating operation, the second gas header 63 merges streams of
refrigerant flowing in from the plurality of heat-transfer tubes
45b and causes the refrigerant to flow to the second gas pipe
43b.
[0097] In Embodiment 2, the height of the first heat source side
heat exchanger 3 is equal to the height of the second heat source
side heat exchanger 4, and the number of the heat-transfer tubes
45a is equal to the number of the heat-transfer tubes 45b. Although
FIGS. 13 and 14 illustrate the case where the number of the
heat-transfer tubes 45a and the number of the heat-transfer tubes
45b are 13, the numbers of the heat-transfer tubes 45a and the
heat-transfer tubes 45b are not limited to 13.
[0098] The operation of the refrigeration cycle apparatus 1d in
Embodiment 2 is similar to the operation procedure described with
reference to FIG. 5, and thus a detailed description thereof is
omitted.
[0099] To explain functions and effects achieved by the
refrigeration cycle apparatus 1d in Embodiment 2 in an
easy-to-understand fashion, a configuration of a refrigeration
cycle apparatus in a comparative example will be described. FIG. 15
is a refrigerant circuit diagram illustrating an example
configuration of the refrigeration cycle apparatus in the
comparative example. Components that are the same as components
described with reference to FIGS. 1 and 12 are denoted by the same
reference signs, and a detailed description thereof is omitted.
[0100] As illustrated in FIG. 15, a refrigeration cycle apparatus
100 in the comparative example includes a heat source side unit
110, the load side units 20a and 20b, and a controller 130. On the
basis of a direction in which refrigerant flows during the
defrosting operation, a refrigerant temperature sensor 121 is
provided in the liquid pipe 47 downstream from a position at which
the first liquid pipe 44a and the second liquid pipe 44b are
joined. The refrigerant temperature sensor 121 detects a
temperature Tr of refrigerant that flows through the liquid pipe 47
and transmits information on the temperature Tr of refrigerant to
the controller 130. A hardware configuration of the controller 130
is similar to the configuration described with reference to FIGS. 3
and 4, and thus a detailed description thereof is omitted.
[0101] In comparison with the configuration illustrated in FIG. 12,
the opening-and-closing valve 7 illustrated in FIG. 1 is not
provided in the second liquid pipe 44b in the heat source side unit
110 illustrated in FIG. 15. When the refrigeration cycle apparatus
100 performs the defrosting operation, the controller 130 compares
the temperature Tr of refrigerant with a predetermined temperature
threshold Tc. Subsequently, when the temperature Tr of refrigerant
reaches not less than the temperature threshold Tc, the controller
130 determines that defrosting has been completed. The temperature
threshold Tc is, for example, 10 degrees C. The relationship
between the temperature thresholds Tb and Tc is Tc>Tb.
Furthermore, when the temperature threshold Tc is compared with the
temperature threshold Ta described in Modification 2, the
relationship of Ta<Tc is established.
[0102] Next, the operation of the refrigeration cycle apparatus 100
in the comparative example illustrated in FIG. 15 will be described
with reference to FIG. 16. FIG. 16 is a flowchart illustrating an
example of an operation procedure performed by the refrigeration
cycle apparatus in the comparative example illustrated in FIG. 15.
Assume that the refrigeration cycle apparatus 100 is performing the
heating operation before starting the operation procedure
illustrated in FIG. 16.
[0103] The controller 130 determines whether or not the temperature
Te of refrigerant has reached not more than the temperature
threshold T0 (step S1001). When the temperature Te of refrigerant
reaches not more than the temperature threshold T0 in step S1001,
the controller 130 determines that frost has adhered to the heat
source side heat exchanger 15 and controls the flow switching
device 5 to switch between the flow passages (step S1002). Thus,
the refrigerant discharged from the compressor 2 flows through the
flow switching device 5 and flows into the heat source side heat
exchanger 15.
[0104] Subsequently, the controller 130 determines whether or not
the temperature Tr of refrigerant is not less than the temperature
threshold Tc (step S1003). When the temperature Tr of refrigerant
reaches not less than the temperature threshold Tc in step S1003,
the controller 130 determines that defrosting of the heat source
side heat exchanger 15 has been completed and controls the flow
switching device 5 to switch between the flow passages (step
S1004). The operation mode of the refrigeration cycle apparatus 100
returns from the defrosting operation to the heating operation.
[0105] While the refrigeration cycle apparatus 100 is performing
the defrosting operation, in the first heat source side heat
exchanger 3 illustrated in FIG. 13, gaseous refrigerant flows into
the middle portion of the first gas header 61 from the first gas
pipe 43a. The gaseous refrigerant having flowed into the first gas
header 61 is split into streams flowing through the plurality of
heat-transfer tubes 45a, and the refrigerant is likely to
accumulate in a lower heat-transfer tube 45a in the first heat
source side heat exchanger 3 due to pressure loss. As in the first
heat source side heat exchanger 3, in the second heat source side
heat exchanger 4 illustrated in FIG. 14, refrigerant is likely to
accumulate in a lower heat-transfer tube 45b in the second heat
source side heat exchanger 4 in the defrosting operation.
[0106] FIG. 17 includes graphs illustrating an example of the
relationship between a refrigerant flow rate and a position of a
heat source side heat exchanger during the defrosting operation. In
FIG. 17, the horizontal axis represents refrigerant flow rate, and
the vertical axis represents height Hu of a heat-transfer tube 45a
in a vertical direction (Z-axis arrow direction) of the first heat
source side heat exchanger 3 illustrated in FIG. 13. In the
vertical axis in FIG. 17, among the plurality of heat-transfer
tubes 45a in the first heat source side heat exchanger 3, the
height of a lowermost heat-transfer tube 45a is denoted by Hu1, the
height of an uppermost heat-transfer tube 45a is denoted by Hun. In
FIG. 17, a solid line graph represents the case of the
refrigeration cycle apparatus 1d in Embodiment 2, and a dashed line
graph represents the case of the refrigeration cycle apparatus 100
in the comparative example illustrated in FIG. 15. Furthermore, the
second heat source side heat exchanger 4 also has a tendency
similar to that of the graphs illustrated in FIG. 17, and thus a
description of the case of the second heat source side heat
exchanger 4 is omitted here.
[0107] In the defrosting operation performed by the refrigeration
cycle apparatus 100 in the comparative example, when refrigerant is
split into streams flowing through the first heat source side heat
exchanger and the second heat source side heat exchanger, a
refrigerant flow rate in a lower section in the heat source side
heat exchanger 15 is smaller than that in an upper section as
represented by the dashed line graph in FIG. 17. This is because,
in the case where refrigerant is split into streams flowing through
a plurality of heat-transfer tubes from a middle portion of a
header as described with reference to FIGS. 13 and 14, the flow of
refrigerant deteriorates due to pressure loss and the refrigerant
is likely to accumulate in the lower section.
[0108] Because of this, in the refrigeration cycle apparatus 100 in
the comparative example, in consideration of a flow rate of
refrigerant that flows to a lower heat-transfer tube in the heat
source side heat exchanger 15, it takes a long time for defrosting
of the heat source side heat exchanger 15 to be completed, and the
temperature threshold Tc is set to a high value. As a result, as
represented by the dashed line graph in FIG. 17, the refrigerant
uselessly flows in the upper section until defrosting of the lower
heat-transfer tube in the heat source side heat exchanger 15 is
completed.
[0109] On the other hand, in the refrigeration cycle apparatus 1d
in Embodiment 2, as represented by the solid line graph in FIG. 17,
refrigerant flow rates are less affected by differences in the
heights of the heat-transfer tubes 45a in the first heat source
side heat exchanger 3 than those in the comparative example, and
the plurality of heat-transfer tubes 45a allow the refrigerant to
uniformly flow therethrough. Thus, the temperature threshold Tb can
be set to a temperature lower than the temperature threshold Tc,
and defrosting can be performed more efficiently than in the
comparative example.
[0110] The refrigeration cycle apparatus 1d in Embodiment 2
includes the first gas header 61 and the second gas header 63. In
the defrosting operation, the first gas header 61 splits
refrigerant flowing into the first heat source side heat exchanger
3 into streams flowing through the plurality of heat-transfer tubes
45a, and the second gas header 63 splits refrigerant flowing into
the second heat source side heat exchanger 4 into streams flowing
through the plurality of heat-transfer tubes 45b. The first gas
pipe 43a is connected to the middle portion in the gravity
direction of the first gas header 61, and the second gas pipe 43b
is connected to the middle portion in the gravity direction of the
second gas header 63.
[0111] In Embodiment 2, in the defrosting operation, as described
in Embodiment 1, when the opening degree of the opening-and-closing
valve 7 is adjusted, flow rates of respective refrigerant streams
that flow to the first heat source side heat exchanger 3 and the
second heat source side heat exchanger 4 are increased. In
Embodiment 2, accumulation of refrigerant in a lower section in the
heat source side heat exchanger caused by differences in the
heights of the heat-transfer tubes is inhibited, and a flow rate of
refrigerant in the lower section increases. As a result, frost
having adhered to the lower section in the heat source side heat
exchanger can be removed reliably and efficiently. The temperature
thresholds Ta and Tb can be set to a value smaller than the
temperature threshold Tc in the comparative example, and thus a
defrosting time period is reduced in comparison with that in the
comparative example, thereby enabling efficient defrosting.
Embodiment 3
[0112] A refrigeration cycle apparatus in Embodiment 3 is a
refrigeration cycle apparatus in which the number of heat-transfer
tubes in the first heat source side heat exchanger is different
from the number of heat-transfer tubes in the second heat source
side heat exchanger. In Embodiment 3, components that are the same
as components described in Embodiments 1 and 2 are denoted by the
same reference signs, and a detailed description thereof is
omitted.
[0113] A configuration of the refrigeration cycle apparatus in
Embodiment 3 will be described. FIG. 18 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus according to Embodiment 3. A refrigeration cycle
apparatus 1e includes a heat source side unit 10e. The first heat
source side heat exchanger 3 provided in the heat source side unit
10e includes a first division heat exchanger 3-1 and a second
division heat exchanger 3-2 that are connected in parallel.
[0114] The first gas pipe 43a is split into gas branch pipes 43a-1
and 43-2. The gas branch pipe 43a-1 is connected to the first
division heat exchanger 3-1, and the gas branch pipe 43a-2 is
connected to the second division heat exchanger 3-2. The first
liquid pipe 44a is split into liquid branch pipes 44a-1 and 44a-2.
The liquid branch pipe 44a-1 is connected to the first division
heat exchanger 3-1, and the liquid branch pipe 44a-2 is connected
to the second division heat exchanger 3-2.
[0115] In the first division heat exchanger 3-1, the first gas
header 61 is provided on a gas branch pipe 43a-1 side, and the
first liquid header 62 is provided on a liquid branch pipe 44a-1
side. In the second division heat exchanger 3-2, a first gas header
65 is provided on a gas branch pipe 43a-2 side, and a first liquid
header 66 is provided on a liquid branch pipe 44a-2 side. A
configuration of the first gas header 65 is similar to that of the
first gas header 61, a configuration of the first liquid header 66
is similar to that of the first liquid header 62, and thus a
detailed description of these is omitted.
[0116] FIG. 19 is an external perspective view illustrating an
example configuration of the heat source side unit illustrated in
FIG. 18. FIG. 20 is an external perspective view of the heat source
side unit illustrated in FIG. 18 as seen from a direction different
from that in FIG. 19. The first division heat exchanger 3-1 and the
second division heat exchanger 3-2 have the same height that is the
length in a direction (Z-axis arrow direction) perpendicular to the
ground, and the height is denoted by L1. When the height of the
second heat source side heat exchanger 4 is denoted by L2, the
relationship between the heights L1 and L2 is L2<L1. In example
configurations illustrated in FIGS. 19 and 20, for example, the
relationship of L2=L1.times.(2/3) is established.
[0117] FIG. 21 is a schematic view illustrating the layout of the
heat source side heat exchangers in the heat source side unit
illustrated in FIG. 20 as seen from above. The first division heat
exchanger 3-1 and the second division heat exchanger 3-2 as seen
from above are L-shaped as illustrated in FIG. 21. The second heat
source side heat exchanger 4 as seen from above is linear-shaped as
illustrated in FIG. 21. In an example configuration illustrated in
FIG. 21, although the first division heat exchanger 3-1 is
L-shaped, if the first division heat exchanger 3-1 is straightened
into a linear shape, the linear length of the first division heat
exchanger 3-1 is equal to the linear length of the second heat
source side heat exchanger 4.
[0118] FIG. 22 is a side view illustrating an example configuration
of the first division heat exchanger illustrated in FIG. 19. The
second division heat exchanger 3-2 has the same configuration as
the first division heat exchanger 3-1, and thus the second division
heat exchanger 3-2 is not illustrated in FIG. 22. Furthermore, FIG.
22 illustrates the first division heat exchanger 3-1 obtained by
straightening the L-shaped first division heat exchanger 3-1
illustrated in FIG. 21 into a linear shape. FIG. 23 is a side view
illustrating an example configuration of the second heat source
side heat exchanger illustrated in FIG. 20. For convenience of
explanation, FIGS. 22 and 23 illustrate the X axis and the Z axis
to define directions. However, an X-axis arrow does not have to
correspond to X-axis arrows illustrated in FIGS. 19 and 20.
[0119] The number of heat-transfer tubes 45a in the first division
heat exchanger 3-1 illustrated in FIG. 22 is 13. The number of
heat-transfer tubes 45b in the second heat source side heat
exchanger 4 illustrated in FIG. 23 is 9. The number of
heat-transfer tubes 45a in the first division heat exchanger 3-1 is
larger than the number of heat-transfer tubes 45b in the second
heat source side heat exchanger 4. A ratio of the number of
heat-transfer tubes 45a in the first division heat exchanger 3-1 to
the number of heat-transfer tubes 45b in the second heat source
side heat exchanger 4 is a value close to a ratio of the height L1
of the first heat source side heat exchanger 3 to the height L2 of
the second heat source side heat exchanger 4 (L1:L2)=3:2.
[0120] In Embodiment 3, assuming that the length of the
heat-transfer tubes 45a illustrated in FIG. 22 is equal to the
length of the heat-transfer tubes 45b illustrated in FIG. 23, the
number of heat-transfer tubes to be defrosted in the first heat
source side heat exchanger 3 is compared with that in the second
heat source side heat exchanger 4. From the ratio of L1/L2, the
number of heat-transfer tubes 45a in the first division heat
exchanger 3-1 is (3/2) times the number of heat-transfer tubes 45b
in the second heat source side heat exchanger 4. The number of
heat-transfer tubes 45a in the first division heat exchanger 3-1 is
equal to the number of heat-transfer tubes 45a in the second
division heat exchanger 3-2, and thus the number of heat-transfer
tubes 45a in the first heat source side heat exchanger 3 is three
times the number of heat-transfer tubes 45b in the second heat
source side heat exchanger 4. Incidentally, the numbers of
heat-transfer tubes 45a in the first division heat exchanger 3-1
and the second division heat exchanger 3-2, and the number of
heat-transfer tubes 45b in the second heat source side heat
exchanger 4 are not limited to the numbers illustrated in FIGS. 22
and 23.
[0121] The operation of the refrigeration cycle apparatus 1e in
Embodiment 3 is similar to the operation procedure described with
reference to FIG. 5, and thus a detailed description thereof is
omitted.
[0122] Referring to FIG. 5, the opening-and-closing valve 7 is
closed from the start of the defrosting operation based on the
operation of step S102 until the time when the time t1 reaches the
time threshold tth1, and thus the first heat source side heat
exchanger 3 is intensively defrosted. Subsequently, the
opening-and-closing valve 7 is opened, and defrosting of the second
heat source side heat exchanger 4 is started, while the refrigerant
also flows to the first heat source side heat exchanger 3. The
amount of refrigerant that flows to the first heat source side heat
exchanger 3 is greater than the amount of refrigerant that flows to
the second heat source side heat exchanger 4. For this reason, even
if the number of heat-transfer tubes 45a in the first heat source
side heat exchanger 3 is larger than the number of heat-transfer
tubes 45b in the second heat source side heat exchanger 4, the
refrigeration cycle apparatus 1e can time the completion of
defrosting of the first heat source side heat exchanger 3 to
coincide with a point in time when defrosting of the second heat
source side heat exchanger 4 is completed.
[0123] In the refrigeration cycle apparatus 1e in Embodiment 3, the
number of heat-transfer tubes 45a in the first heat source side
heat exchanger 3 is larger than the number of heat-transfer tubes
in the second heat source side heat exchanger 4. In Embodiment 3,
the amount of refrigerant that flows to the first heat source side
heat exchanger 3 is greater than the amount of refrigerant that
flows to the second heat source side heat exchanger 4, and thus the
completion of defrosting of the first heat source side heat
exchanger 3 can be timed to coincide with a point in time when
defrosting of the second heat source side heat exchanger 4 is
completed.
(Modification 4)
[0124] A refrigeration cycle apparatus in Modification 4 is a
refrigeration cycle apparatus in which, in the refrigerant circuits
60a and 60b illustrated in FIG. 18, the flow control valve 9 is
provided in the first liquid pipe 44a. In Modification 4,
components that are the same as components described with reference
to FIGS. 18 to 23 are denoted by the same reference signs, and a
detailed description thereof is omitted.
[0125] A configuration of the refrigeration cycle apparatus in
Modification 4 will be described. FIG. 24 is a refrigerant circuit
diagram illustrating an example configuration of the refrigeration
cycle apparatus in Modification 4. In a heat source side unit 10f
in a refrigeration cycle apparatus 1f, the flow control valve 9 is
provided in the first liquid pipe 44a.
[0126] Incidentally, the operation of the refrigeration cycle
apparatus 1f is similar to the procedure illustrated in FIG. 10
except that a point in time when defrosting targets to be defrosted
are switched is determined in accordance with the time t1 measured
by the timer 53 in step S207 illustrated in FIG. 10, and thus a
detailed description thereof is omitted. The refrigerant
temperature sensor 12 may be provided in the liquid pipe 47 near
the confluence of the first liquid pipe 44a and the second liquid
pipe 44b in place of the second liquid pipe 44b.
[0127] In Modification 4, valves that shut off flows of refrigerant
are provided in the respective liquid pipes of the first heat
source side heat exchanger 3 and the second heat source side heat
exchanger 4. In the defrosting operation, the refrigeration cycle
apparatus 1f in Modification 4 performs opening and closing control
of each valve to first defrost the first heat source side heat
exchanger 3 and then to defrost the other second heat source side
heat exchanger 4, and thus defrosting can be performed reliably and
efficiently.
[0128] Although, in Embodiment 3, the description based on the
refrigeration cycle apparatus 1d described in Embodiment 2 has been
given, Embodiment 3 may be applied to the refrigeration cycle
apparatus 1 described in Embodiment 1. Furthermore, in each of
Embodiments 2 and 3, among Modifications 1 to 3, any Modifications
may be combined.
* * * * *