U.S. patent application number 16/344165 was filed with the patent office on 2020-03-05 for heat source-side unit and refrigeration cycle apparatus.
The applicant listed for this patent is Mitsubishi Electric Corporation. Invention is credited to Yohei KATO, Yudai SAKABE, Masahiro TAKAMURA, Tsubasa TANDA.
Application Number | 20200072517 16/344165 |
Document ID | / |
Family ID | 62978132 |
Filed Date | 2020-03-05 |
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United States Patent
Application |
20200072517 |
Kind Code |
A1 |
KATO; Yohei ; et
al. |
March 5, 2020 |
HEAT SOURCE-SIDE UNIT AND REFRIGERATION CYCLE APPARATUS
Abstract
In a heat source-side unit according to the present invention, a
temperature sensor is installed on an inter-column connecting part
included in a plurality of inter-column connecting parts and
located higher than an intermediate position in a vertical
direction of a heat exchanger.
Inventors: |
KATO; Yohei; (Tokyo, JP)
; TANDA; Tsubasa; (Tokyo, JP) ; TAKAMURA;
Masahiro; (Tokyo, JP) ; SAKABE; Yudai; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Mitsubishi Electric Corporation |
Tokyo |
|
JP |
|
|
Family ID: |
62978132 |
Appl. No.: |
16/344165 |
Filed: |
January 24, 2017 |
PCT Filed: |
January 24, 2017 |
PCT NO: |
PCT/JP2017/002311 |
371 Date: |
April 23, 2019 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28F 9/0278 20130101;
F28F 9/0221 20130101; F28F 2215/12 20130101; F28F 9/262 20130101;
F28D 1/0452 20130101; F28D 1/0476 20130101; F25B 49/02 20130101;
F28D 1/0435 20130101; F28D 2021/0068 20130101; F28F 1/128 20130101;
F28F 9/0204 20130101; F25B 2313/0253 20130101; F25B 2313/0315
20130101; F28F 9/0243 20130101; F28F 9/00 20130101 |
International
Class: |
F25B 49/02 20060101
F25B049/02; F28F 1/12 20060101 F28F001/12 |
Claims
1. A heat source-side unit comprising: a heat exchanger including a
plurality of heat exchanging units; and a temperature sensor
configured to measure a temperature of refrigerant flowing through
the heat exchanger, the heat exchanger including a first header
connected to a first heat exchanging unit serving as at least one
of the plurality of heat exchanging units, and including a
plurality of branching units arranged in a vertical direction, a
second header connected to a second heat exchanging unit serving as
at least one of rest of the plurality of heat exchanging units, and
a plurality of inter-column connecting parts configured to connect
parts of a plurality of heat transfer tubes forming the first heat
exchanging unit and parts of a plurality of heat transfer tubes
forming the second heat exchanging unit, and the temperature sensor
being installed on an inter-column connecting part included in the
plurality of inter-column connecting parts, the inter-column
connecting part being connected to an upper branching unit of the
first header at a position higher than an intermediate position in
a vertical direction of the heat exchanger.
2. The heat source-side unit of claim 1, wherein the temperature
sensor is installed on an inter-column connecting part located
uppermost among the plurality of inter-column connecting parts.
3. The heat source-side unit of claim 1, wherein each of the
plurality of heat transfer tubes forming the first heat exchanging
unit has a hairpin part on an end portion of each of the plurality
of heat transfer tubes opposite to an end portion of each of the
plurality of heat transfer tubes near the first header, wherein
each of the plurality of heat transfer tubes forming the second
heat exchanging unit has a hairpin part on an end portion of each
of the plurality of heat transfer tubes opposite to an end portion
of each of the plurality of heat transfer tubes near the second
header, and wherein the plurality of inter-column connecting parts
are disposed near the first header and the second header.
4. The heat source-side unit of claim 1, wherein the first header
is a stacking-type header having a plurality of plate-shaped parts
stacked upon each other.
5. The heat source-side unit of claim 1, wherein the heat transfer
tubes are flat tubes.
6. The heat source-side unit of claim 1, comprising a heat
source-side fan configured to supply air to the heat exchanger,
wherein the first heat exchanging unit and the second heat
exchanging unit are arranged side by side in a passing direction of
the air supplied by the heat source-side fan.
7. A refrigeration cycle apparatus comprising: the heat source-side
unit of claim 1; and a load-side unit connected to the heat
source-side unit.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a U.S. national stage application of
International Application No. PCT/JP2017/002311, filed on Jan. 24,
2017, the contents of which are incorporated herein by
reference.
TECHNICAL FIELD
[0002] The present invention relates to a heat source-side unit
equipped with a heat exchanger including headers, and to a
refrigeration cycle apparatus including the heat source-side
unit.
BACKGROUND
[0003] A heat source-side unit included in a refrigeration cycle
apparatus such as an air-conditioning apparatus or a hot water
supply system is equipped with a heat exchanger. To reduce the
pressure loss of refrigerant flowing through a heat transfer tube,
the heat exchanger usually has passages (paths) formed by a
plurality of heat transfer tubes arranged in parallel to each
other. Refrigerant inlets and refrigerant outlets of the heat
transfer tubes are equipped with headers each corresponding to the
number of paths. Further, the headers are equipped with a
temperature sensor that measures the temperature of the refrigerant
flowing through the heat transfer tubes.
[0004] As such a heat exchanger, a heat exchanger has been proposed
which "includes: two standing header collecting pipes (51, 52); a
plurality of flat tubes (53) arranged in the vertical direction
between the two header collecting pipes (51, 52), with one end of
each of the flat tubes (53) being inserted in one of the header
collecting pipes (51, 52) and the other end of each of the flat
tubes (53) being inserted in the other one of the header collecting
pipes (51, 52); a plurality of fins (55) joined to the flat tubes
(53); a temperature sensor (100) that measures the temperature of
refrigerant in the header collecting pipe (51, 52); an installation
part (110) fixed to an outer circumferential surface of the header
collecting pipe (51, 52) to install the temperature sensor (100) to
the header collecting pipe (51, 52); and a positioning part (120)
fixed to the outer circumferential surface of the header collecting
pipe (51, 52) to determine an installation position of the
temperature sensor (100)," for example (see Patent Literature 1,
for example).
Patent Literature
[0005] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2013-231527
[0006] According to the heat exchanger described in Patent
Literature 1, the positioning part is attached to the installation
position of the temperature sensor to position the temperature
sensor on a header collecting pipe. It is thereby possible to
position the temperature sensor before brazing the header
collecting pipes and the flat tubes together, as compared with a
heat exchanger in which the temperature sensor is positioned after
the header collecting pipes and the flat tubes are brazed together.
Accordingly, it is possible to improve workability in
positioning.
[0007] According to Patent Literature 1, however, the fixing
position of the temperature sensor on the outer circumferential
surface of the header collecting pipe is determined by the
positioning part, with no consideration for the state of the
refrigerant flowing through the header collecting pipe. If the
number of heat transfer tubes is small, and if the temperature
sensor is disposed at the inlet of a subcooling line, therefore,
the temperature sensor is unable to measure the temperature of
two-phase refrigerant.
SUMMARY
[0008] The present invention has been made with the above-described
issue as background, and aims to provide a heat source-side unit
with improved reliability in measuring the temperature of two-phase
gas-liquid refrigerant and a refrigeration cycle apparatus
including the heat source-side unit.
[0009] A heat source-side unit according to an embodiment of the
present invention includes a heat exchanger that includes a
plurality of heat exchanging units and a temperature sensor that
measures a temperature of refrigerant flowing through the heat
exchanger. The heat exchanger includes: a first header connected to
a first heat exchanging unit serving as at least one of the
plurality of heat exchanging units, and including a plurality of
branching units arranged in a vertical direction; a second header
connected to a second heat exchanging unit serving as at least one
of rest of the plurality of heat exchanging units; and a plurality
of inter-column connecting parts that connect parts of a plurality
of heat transfer tubes forming the first heat exchanging unit and
parts of a plurality of heat transfer tubes forming the second heat
exchanging unit. The temperature sensor is installed on an
inter-column connecting part included in the plurality of
inter-column connecting parts and located higher than an
intermediate position in a vertical direction of the heat
exchanger.
[0010] A refrigeration cycle apparatus according to an embodiment
of the present invention includes the above-described heat
source-side unit.
[0011] In the heat source-side unit according to the embodiment of
the present invention, the temperature sensor is installed on the
inter-column connecting part included in the plurality of
inter-column connecting parts and located higher than the
intermediate position in the vertical direction of the heat
exchanger. Accordingly, the measurement of the temperature of
two-phase gas-liquid refrigerant is improved in reliability.
[0012] The refrigeration cycle apparatus according to the
embodiment of the present invention includes the above-described
heat source-side unit. Accordingly, it is possible to optimize the
control of actuators and realize efficient system protection.
BRIEF DESCRIPTION OF DRAWINGS
[0013] FIG. 1 is a circuit configuration diagram schematically
illustrating an example of a refrigerant circuit configuration of a
refrigeration cycle apparatus according to Embodiment of the
present invention.
[0014] FIG. 2 is a circuit configuration diagram schematically
illustrating an example of the refrigerant circuit configuration of
the refrigeration cycle apparatus according to Embodiment of the
present invention.
[0015] FIG. 3 is a perspective view schematically illustrating an
example of a heat exchanger installed in a heat source-side unit
according to Embodiment of the present invention.
[0016] FIG. 4 is a perspective view schematically illustrating
another example of the heat exchanger installed in the heat
source-side unit according to Embodiment of the present
invention.
[0017] FIG. 5 is a top view schematically illustrating an example
of the heat exchanger installed in the heat source-side unit
according to Embodiment of the present invention.
[0018] FIG. 6 is a schematic sectional view taken along line A-A in
FIG. 5.
[0019] FIG. 7 is a schematic diagram illustrating a flow of
refrigerant in the heat exchanger installed in the heat source-side
unit according to Embodiment of the present invention.
[0020] FIG. 8 is a graph schematically illustrating transition of
the state of the refrigerant in the heat exchanger installed in the
heat source-side unit according to Embodiment of the present
invention.
[0021] FIG. 9 is a longitudinal sectional view illustrating an
example of an upper branching unit forming a first header of the
heat exchanger installed in the heat source-side unit according to
Embodiment of the present invention.
[0022] FIG. 10 is a perspective view illustrating another example
of the upper branching unit forming the first header of the heat
exchanger installed in the heat source-side unit according to
Embodiment of the present invention.
[0023] FIG. 11 is a perspective view illustrating a configuration
example of the first header of the heat exchanger installed in the
heat source-side unit according to Embodiment of the present
invention.
[0024] FIG. 12 is a perspective view illustrating another
configuration example of the first header of the heat exchanger
installed in the heat source-side unit according to Embodiment of
the present invention.
[0025] FIG. 13 is a graph for illustrating a pressure loss in a
header not including a plurality of branching units.
[0026] FIG. 14 is a graph for illustrating a pressure loss in a
header including a plurality of branching units.
[0027] FIG. 15 is a perspective view schematically illustrating
still another example of the heat exchanger installed in the heat
source-side unit according to Embodiment of the present
invention.
[0028] FIG. 16 is a table for illustrating combinations of heat
transfer tubes and header passages.
DETAILED DESCRIPTION
[0029] A heat source-side unit and a refrigeration cycle apparatus
according to the present invention will be described below with the
drawings.
[0030] Configurations and operations described below are merely
illustrative, and the heat source-side unit and the refrigeration
cycle apparatus according to the present invention are not limited
to such configurations and operations. Further, in the drawings,
identical or similar parts are assigned with identical reference
signs, or some of identical or similar parts are not assigned with
reference signs. Further, illustration of detailed structures is
simplified or omitted as appropriate. Further, redundant or similar
descriptions will be simplified or omitted as appropriate.
[0031] Further, the following description will be given of a case
in which the heat source-side unit according to the present
invention is applied to an air-conditioning apparatus, which is an
example of the refrigeration cycle apparatus. However, the heat
source-side unit according to the present invention is not limited
to such a case, and may be applied to another refrigeration cycle
apparatus (a hot water supply system, for example) including a
refrigerant cycle circuit, for example. Further, the following
description will be given of a case in which the refrigeration
cycle apparatus is switchable between a temperature increasing
operation and a cooling operation. However, the refrigeration cycle
apparatus is not limited to such a case, and may perform only the
temperature increasing operation or the cooling operation.
[0032] Each of FIG. 1 and FIG. 2 is a circuit configuration diagram
schematically illustrating an example of a refrigerant circuit
configuration of a refrigeration cycle apparatus (hereinafter
referred to as the refrigeration cycle apparatus 100) according to
Embodiment of the present invention. The refrigeration cycle
apparatus 100 will be described based on FIG. 1. An
air-conditioning apparatus will be described with FIG. 1 as an
example of the refrigeration cycle apparatus 100. Therefore, the
temperature increasing operation corresponds to a heating
operation, and the cooling operation corresponds to a cooling
operation. Further, FIG. 1 illustrates a flow of refrigerant during
the heating operation, and FIG. 2 illustrates a flow of refrigerant
during the cooling operation.
<Configuration of Refrigeration Cycle Apparatus 100>
[0033] The refrigeration cycle apparatus 100 includes a refrigerant
circuit that circulates refrigerant. The refrigeration cycle
apparatus 100 performs the cooling operation or the heating
operation by circulating the refrigerant through the refrigerant
circuit.
[0034] As illustrated in FIG. 1, the refrigeration cycle apparatus
100 includes a heat source-side unit 100A and a load-side unit
100B.
[0035] The heat source-side unit 100A and the load-side unit 100B
are connected to each other via the refrigerant circuit, in which
elements included in the heat source-side unit 100A and elements
included in the load-side unit 100B are connected with refrigerant
pipes 15.
[0036] These elements include a compressor 10, a flow switching
device 11, a heat exchanger 50, an expansion device 12, and a
load-side heat exchanger 13.
[Heat Source-Side Unit 100A]
[0037] The heat source-side unit 100A is installed in a space
different from an air-conditioned space (an outdoor space such as
outdoors, an attic, or a basement, for example), and has a function
of supplying cooling energy or heating energy to the load-side unit
100B.
[0038] The heat source-side unit 100A includes the compressor 10,
the flow switching device 11, the heat exchanger (heat source-side
heat exchanger) 50, the expansion device 12, a heat source-side fan
50A, a controller 40, and a temperature sensor 80.
[0039] The compressor 10 compresses and discharges the refrigerant
circulating through the refrigerant circuit. The refrigerant
compressed by the compressor 10 is discharged therefrom and sent to
the heat exchanger 50 or the load-side heat exchanger 13. The
compressor 10 may be formed as a rotary compressor, a scroll
compressor, a screw compressor, or a reciprocating compressor, for
example.
[0040] The flow switching device 11 is disposed on a discharge side
of the compressor 10, and switches the flow of refrigerant between
the heating operation and the cooling operation. That is, during
the cooling operation, the flow switching device 11 is switched to
connect the compressor 10 with the heat exchanger 50. During the
heating operation, the flow switching device 11 is switched to
connect the compressor 10 with the load-side heat exchanger 13. The
flow switching device 11 may be formed by a four-way valve, for
example. The flow switching device 11, however, may employ a
combination of two-way valves or three-way valves.
[0041] The heat exchanger 50 functions as an evaporator during the
heating operation, and functions as a condenser during the cooling
operation. When the heat exchanger 50 functions as an evaporator,
the heat exchanger 50 exchanges heat between low-temperature,
low-pressure refrigerant flowing from the expansion device 12 and
air supplied by the heat source-side fan 50A, and thereby
low-temperature, low-pressure liquid or two-phase refrigerant is
evaporated. When the heat exchanger 50 functions as a condenser, on
the other hand, the heat exchanger 50 exchanges heat between
high-temperature, high-pressure refrigerant discharged from the
compressor 10 and air supplied by the heat source-side fan 50A, and
thereby high-temperature, high-pressure gas refrigerant is
condensed.
[0042] The heat exchanger 50 will be described in detail later.
[0043] The expansion device 12 expands the refrigerant flowing from
the heat exchanger 50 or the load-side heat exchanger 13, to
thereby reduce the pressure of the refrigerant. The expansion
device 12 may be formed by an electric expansion valve capable of
adjusting the flow rate of the refrigerant, for example. As well as
the electric expansion valve, a mechanical expansion valve
employing a diaphragm as a pressure receiving part or a capillary
tube, for example, is also be applicable to the expansion device
12.
[0044] The heat source-side fan 50A, which is attached to the heat
exchanger 50, rotates to supply air to the heat exchanger 50. The
heat source-side fan 50A may employ one of various types of fans,
such as a propeller fan and a turbo fan, for example. The
condensation capacity or evaporation capacity of the heat exchanger
50 is adjusted with the rotation speed of the heat source-side fan
50A.
[0045] The controller 40 controls the driving frequency of the
compressor 10 depending on the required cooling or heating
capacity. The controller 40 further controls the opening degree of
the expansion device 12 depending on the required cooling or
heating capacity. The controller 40 further controls the respective
rotation speeds of the heat source-side fan 50A and a load-side fan
13A. The controller 40 further controls the switching of the flow
switching device 11 depending on the operation mode.
[0046] That is, based on an operation instruction from a user, the
controller 40 controls actuators (the compressor 10, the flow
switching device 11, the expansion device 12, the heat source-side
fan 50A, and the load-side fan 13A) by using information
transmitted from the later-described temperature sensor 80,
not-illustrated other temperature sensors, and not-illustrated
pressure sensors. In the example illustrated here, the controller
40 is included in the heat source-side unit 100A. The controller
40, however, is not limited to this position. For example, the
controller 40 may be included in the load-side unit 100B, or may be
disposed outside the heat source-side unit 100A and the load-side
unit 100B.
[0047] The controller 40 may be formed by hardware such as a
circuit device that realizes functions of the controller 40, or may
be formed by an arithmetic device such as a microcomputer or a CPU
and software executed thereon.
[Load-Side Unit 100B]
[0048] The load-side unit 100B is installed in a space for
supplying cooling energy or heating energy to the air-conditioned
space (the air-conditioned space such as an indoor space or a space
communicating with the air-conditioned space via a duct, for
example), and has a function of cooling or heating the
air-conditioned space with the cooling energy or heating energy
supplied by the heat source-side unit 100A.
[0049] The load-side unit 100B includes the load-side heat
exchanger 13 and the load-side fan 13A.
[0050] The load-side heat exchanger 13 functions as a condenser
during the heating operation, and functions as an evaporator during
the cooling operation. When the load-side heat exchanger 13
functions as a condenser, the load-side heat exchanger 13 exchanges
heat between high-temperature, high-pressure refrigerant discharged
from the compressor 10 and air supplied by the load-side fan 13A,
and thereby high-temperature, high-pressure gas refrigerant is
condensed. When the load-side heat exchanger 13 functions as an
evaporator, on the other hand, the load-side heat exchanger 13
exchanges heat between low-temperature, low-pressure refrigerant
flowing from the expansion device 12 and air supplied by the
load-side fan 13A, and thereby low-temperature, low-pressure liquid
or two-phase refrigerant is evaporated.
[0051] The load-side heat exchanger 13 may be formed as a
fin-and-tube heat exchanger, a microchannel heat exchanger, a
shell-and-tube heat exchanger, a heat pipe heat exchanger, a
double-pipe heat exchanger, or a plate heat exchanger, for example.
In the example illustrated here, the load-side heat exchanger 13 is
a heat exchanger that exchanges heat between air and refrigerant.
The condensation capacity or evaporation capacity of the load-side
heat exchanger 13 is adjusted with the rotation speed of the
load-side fan 13A.
[0052] The load-side fan 13A, which is attached to the load-side
heat exchanger 13, rotates to supply air to the load-side heat
exchanger 13. The load-side fan 13A may employ one of various types
of fans, such as a propeller fan, a crossflow fan, a sirocco fan,
and a turbo fan, for example.
[0053] FIG. 1 illustrates an example in which one load-side unit
100B is connected to one heat source-side unit 100A. However, the
number of heat source-side units 100A and the number of load-side
units 100B are not particularly limited. The refrigeration cycle
apparatus 100 may be configured to include a plurality of heat
source-side units 100A and a plurality of load-side units 100B
connected in parallel or in series.
[0054] Further, the expansion device 12 may be included in the
load-side unit 100B.
[Refrigerant Usable in Refrigeration Cycle Apparatus 100]
[0055] The refrigerant used in the refrigeration cycle apparatus
100 includes a non-azeotropic refrigerant mixture, a
near-azeotropic refrigerant mixture, and single refrigerant.
[0056] The non-azeotropic refrigerant mixture includes R407C
(R32/R125/R134a), which is the HFC (hydrofluorocarbon) refrigerant.
The non-azeotropic refrigerant mixture is a mixture of refrigerants
having different boiling points, and thus has a characteristic of
having different composition ratios between liquid-phase
refrigerant and gas-phase refrigerant.
[0057] The near-azeotropic refrigerant mixture includes R410A
(R32/R125) and R404A (R125/R143a/R134a), which are the HFC
refrigerant. The near-azeotropic refrigerant mixture has a
characteristic similar to that of the non-azeotropic refrigerant
mixture, and also has a characteristic of having an operating
pressure approximately 1.6 times greater than that of R22.
[0058] The single refrigerant includes R22 and R134a, which are the
HCFC (hydrochlorofluorocarbon) refrigerant and the HFC refrigerant,
respectively. The single refrigerant is not a mixture, and thus has
a characteristic of being easy to handle. In particular, the HCFC
refrigerant such as R22, which has been used in refrigeration cycle
apparatuses in the past, is pointed out to be higher in ozone
depletion potential and more environmentally harmful than the HFC
refrigerant. With this as background, the transition to refrigerant
with a lower ozone depletion potential has been in progress in
recent years.
<Operations Performed by Refrigeration Cycle Apparatus
100>
[0059] Operations performed by the refrigeration cycle apparatus
100 will be described as well as of flows of the refrigerant.
[0060] The refrigeration cycle apparatus 100 is capable of
performing the cooling operation or the heating operation in the
load-side unit 100B based on an instruction from the load-side unit
100B.
[0061] The respective operations of the actuators are controlled by
the controller 40 that receives input of information transmitted
from various sensors (the temperature sensors including the
temperature sensor 80 and the pressure sensors) and a remote
controller.
[Heating Operation]
[0062] The heating operation performed by the refrigeration cycle
apparatus 100 will first be described. The flow of the refrigerant
during the heating operation performed by the refrigeration cycle
apparatus 100 is illustrated in FIG. 1.
[0063] When the refrigeration cycle apparatus 100 performs the
heating operation, the flow switching device 11 is switched in the
heat source-side unit 100A to allow the refrigerant discharged from
the compressor 10 to flow into the heat exchanger 50 via the
load-side heat exchanger 13. Specifically, in a heating operation
mode, the refrigerant sequentially flows through the compressor 10,
the flow switching device 11, the load-side heat exchanger 13, the
expansion device 12, and the heat exchanger 50.
[0064] Low-temperature, low-pressure refrigerant is compressed by
the compressor 10, and is discharged from the compressor 10 as
high-temperature, high-pressure gas refrigerant. The
high-temperature, high-pressure gas refrigerant discharged from the
compressor 10 flows into the load-side heat exchanger 13 via the
flow switching device 11. The refrigerant flowing into the
load-side heat exchanger 13 exchanges heat (is condensed) with air
supplied by the load-side fan 13A attached to the load-side heat
exchanger 13, and flows from the load-side heat exchanger 13 as
high-temperature, high-pressure liquid refrigerant. With the heat
transferred from the refrigerant to the air in the load-side heat
exchanger 13, the air is heated. The heated air is supplied to the
air-conditioned space to thereby heat the air-conditioned
space.
[0065] The high-temperature, high-pressure liquid refrigerant
flowing from the load-side heat exchanger 13 is converted into
low-temperature, low-pressure liquid refrigerant (or two-phase
refrigerant) by the expansion device 12. The refrigerant flows into
the heat exchanger 50. The refrigerant flowing into the heat
exchanger 50 exchanges heat (is evaporated) with air supplied by
the heat source-side fan 50A attached to the heat exchanger 50, and
flows from the heat exchanger 50 as low-temperature, low-pressure
gas refrigerant. The refrigerant flowing from the heat exchanger 50
is again suctioned into the compressor 10 via the flow switching
device 11. During the continuation of the heating operation, the
cycle from the discharge of the refrigerant from the compressor 10
to the suction of the refrigerant into the compressor 10 is
repeated.
[Cooling Operation]
[0066] The cooling operation performed by the refrigeration cycle
apparatus 100 will now be described. The flow of the refrigerant
during the cooling operation performed by the refrigeration cycle
apparatus 100 is illustrated in FIG. 2.
[0067] When the refrigeration cycle apparatus 100 performs the
cooling operation, the flow switching device 11 is switched in the
heat source-side unit 100A to allow the refrigerant discharged from
the compressor 10 to flow into the load-side heat exchanger 13 via
the heat exchanger 50. Specifically, in the cooling operation, the
refrigerant sequentially flows through the compressor 10, the flow
switching device 11, the heat exchanger 50, the expansion device
12, and the load-side heat exchanger 13.
[0068] Low-temperature, low-pressure refrigerant is compressed by
the compressor 10, and is discharged from the compressor 10 as
high-temperature, high-pressure gas refrigerant. The
high-temperature, high-pressure gas refrigerant discharged from the
compressor 10 flows into the heat exchanger 50 via the flow
switching device 11. The refrigerant flowing into the heat
exchanger 50 exchanges heat (is condensed) with air supplied by the
heat source-side fan 50A attached to the heat exchanger 50, and
flows from the heat exchanger 50 as low-temperature, high-pressure
liquid refrigerant.
[0069] The low-temperature, high-pressure liquid refrigerant
flowing from the heat exchanger 50 is converted into
low-temperature, low-pressure liquid refrigerant (or two-phase
refrigerant) by the expansion device 12, and flows into the
load-side heat exchanger 13. The refrigerant flowing into the
load-side heat exchanger 13 exchanges heat (is evaporated) with air
supplied by the load-side fan 13A attached to the load-side heat
exchanger 13, and flows from the load-side heat exchanger 13 as
low-temperature, low-pressure gas refrigerant. With the refrigerant
receiving heat from the air in the load-side heat exchanger 13, the
air is cooled. The cooled air is supplied to the air-conditioned
space to thereby cool the air-conditioned space. The refrigerant
flowing from the load-side heat exchanger 13 is again suctioned
into the compressor 10 via the flow switching device 11. During the
continuation of the cooling operation, the cycle from the discharge
of the refrigerant from the compressor 10 to the suction of the
refrigerant into the compressor 10 is repeated.
<Details of Heat Source-Side Unit 100A>
[0070] Details of the heat source-side unit 100A according to
Embodiment of the present invention will now be described.
[0071] FIG. 3 is a perspective view schematically illustrating an
example of the heat exchanger 50 installed in the heat source-side
unit 100A. FIG. 4 is a perspective view schematically illustrating
another example of the heat exchanger 50 installed in the heat
source-side unit 100A. The heat source-side unit 100A will be
described in detail with reference to FIGS. 3 and 4 in addition to
FIGS. 1 and 2.
[0072] As described above, the heat source-side unit 100A is
equipped with the heat exchanger 50, which functions as a heat
source-side heat exchanger.
[0073] The heat source-side unit 100A is further equipped with the
temperature sensor 80 that measures the temperature of the
refrigerant flowing through the heat exchanger 50. Temperature
information obtained through the measurement with the temperature
sensor 80 is transmitted to the controller 40 to be used in
controlling the actuators.
[0074] The heat exchanger 50 includes a first heat exchanging unit
51A disposed on the upwind side in a passing direction of air
passing through the heat exchanger 50 (a void arrow in the
drawing), a second heat exchanging unit 51B disposed on the
downwind side in the passing direction of the air, a first header
60 connected to the first heat exchanging unit 51A, and a second
header 70 connected to the second heat exchanging unit 51B.
[0075] In the following description, the first heat exchanging unit
51A and the second heat exchanging unit 51B may be collectively
referred to as the heat exchanging units. Further, the first header
60 and the second header 70 may be collectively referred to as the
header units.
[0076] The first heat exchanging unit 51A and the second heat
exchanging unit 51B are arranged side by side along the passing
direction of the air passing through the heat exchanger 50 (the
void arrow in the drawing).
[0077] Similarly to the first heat exchanging unit 51A and the
second heat exchanging unit 51B, the first header 60 and the second
header 70 are arranged side by side along the passing direction of
the air passing through the heat exchanger 50 (the void arrow in
the drawing).
[0078] Embodiment illustrates an example in which the heat
exchanger 50 is configured to have two columns: the first heat
exchanging unit 51A and the second heat exchanging unit 51B. The
heat exchanger 50, however, may be configured to have three or more
columns. In this case, the heat exchanger 50 may additionally
include a heat exchanging unit having a configuration equivalent to
the configuration of the first heat exchanging unit 51A or the
second heat exchanging unit 51B.
[First Heat Exchanging Unit 51A]
[0079] The first heat exchanging unit 51A includes a plurality of
heat transfer tubes 52A and a plurality of fins 53A joined to the
plurality of heat transfer tubes 52A by a method such as brazing,
for example.
[0080] The heat transfer tubes 52A are flat tubes, for example, and
a plurality of passages are formed inside each of the heat transfer
tubes 52A.
[0081] The heat transfer tubes 52A are arranged in a plurality of
rows in a direction crossing the passing direction of the passing
air (the void arrow in the drawing). One end portion and an other
end portion of each of the plurality of heat transfer tubes 52A are
arranged side by side near the first header 60 to face the first
header 60.
[0082] Further, the one end portion and the other end portion of
each of the plurality of heat transfer tubes 52A are connected by a
hairpin part 54A bent into a hairpin shape.
[Second Heat Exchanging Unit 51B]
[0083] The second heat exchanging unit 51B includes a plurality of
heat transfer tubes 52B and a plurality of fins 53B joined to the
plurality of heat transfer tubes 52B by a method such as brazing,
for example.
[0084] The heat transfer tubes 52B are flat tubes, for example, and
a plurality of passages are formed inside each of the heat transfer
tubes 52B.
[0085] The heat transfer tubes 52B are arranged in a plurality of
rows in a direction crossing the passing direction of the passing
air (the void arrow in the drawing). One end portion and an other
end portion of each of the plurality of heat transfer tubes 52B are
arranged side by side near the second header 70 to face the second
header 70.
[0086] Further, the one end portion and the other end portion of
each of the plurality of heat transfer tubes 52B are connected by a
hairpin part 54B bent into a hairpin shape.
[0087] The heat transfer tubes 52A and 52B are not limited to the
flat tubes, and may be cylindrical pipes. Further, in the
illustrated example, each of the heat transfer tubes 52A includes
the hairpin part 54A bent into a U-shape, and each of the heat
transfer tubes 52B includes the hairpin part 54B bent into a
U-shape. In place of the hairpin part 54A or 54B, however, a pipe
such as a U-shaped pipe having passages formed therein may be used
as a part separated from the heat transfer tube 52A or 52B to form
bent passages.
[First Header 60]
[0088] The first header 60 functions as a liquid header, and is
formed by two or more branching units arranged in the vertical
direction. In FIG. 3, a branching unit of the two or more branching
units disposed on the upper side in the vertical direction is
illustrated as an upper branching unit 60a, and a branching unit of
the two or more branching units disposed on the lower side in the
vertical direction is illustrated as a lower branching unit 60b.
The upper branching unit 60a is connected to some of the heat
transfer tubes 52A allocated thereto, and the lower branching unit
60b is connected to some of the heat transfer tubes 52A allocated
thereto.
[0089] Herein, the vertical direction means the vertical direction
of the heat exchanger 50 as installed in the heat source-side unit
100A.
[0090] With the first header 60 formed by the plurality of
branching units, the head difference between paths due to the
pressure loss in the heat transfer tubes 52A is mitigated, and the
difference in the flow rate of the refrigerant between the paths is
reduced. The reason therefor will be described in detail later.
[0091] As illustrated in FIG. 4, the upper branching unit 60a is
connected to a refrigerant pipe 15a via a connecting pipe 61a.
[0092] Further, the lower branching unit 60b is connected to a
refrigerant pipe 15b via a connecting pipe 61b.
[0093] Further, the refrigerant pipes 15a and 15b are connected to
the corresponding refrigerant pipe 15 via a distributor 85.
[0094] The connecting pipes 61a and 61b are cylindrical pipes, for
example.
[0095] Inside the upper branching unit 60a, at least one
distributing and combining passage 65a is formed. When the heat
exchanger 50 operates as an evaporator, the distributing and
combining passage 65a serves as a distributing passage that allows
the refrigerant flowing from the refrigerant pipe 15a to flow into
the corresponding plurality of heat transfer tubes 52A of the first
heat exchanging unit 51A to be distributed thereto. Further, when
the heat exchanger 50 operates as a condenser (radiator), the
distributing and combining passage 65a serves as a combining
passage that allows flows of refrigerant flowing from the
corresponding plurality of heat transfer tubes 52A of the first
heat exchanging unit 51A to combine together and flow into the
refrigerant pipe 15a. That is, one side of the distributing and
combining passage 65a is connected to the corresponding plurality
of heat transfer tubes 52A, and the other side of the distributing
and combining passage 65a is connected to the refrigerant pipe
15a.
[0096] Inside the lower branching unit 60b, at least one
distributing and combining passage 65b is formed. When the heat
exchanger 50 operates as an evaporator, the distributing and
combining passage 65b serves as a distributing passage that allows
the refrigerant flowing from the refrigerant pipe 15b to flow into
the corresponding plurality of heat transfer tubes 52A of the first
heat exchanging unit 51A to be distributed thereto. Further, when
the heat exchanger 50 operates as a condenser (radiator), the
distributing and combining passage 65b serves as a combining
passage that allows flows of refrigerant flowing from the
corresponding plurality of heat transfer tubes 52A of the first
heat exchanging unit 51A to combine together and flow into the
refrigerant pipe 15b. That is, one side of the distributing and
combining passage 65b is connected to the corresponding plurality
of heat transfer tubes 52A, and the other side of the distributing
and combining passage 65b is connected to the refrigerant pipe
15b.
[Second Header 70]
[0097] The second header 70 functions as a gas header. FIGS. 3 and
4 illustrate, as an example, the heat exchanger 50 including one
second header 70 for the first header 60 formed by a plurality of
branching units. The second header 70 may also be formed by a
plurality of branching units similarly to the first header 60.
[0098] As illustrated in FIG. 4, the second header 70 is connected
to the corresponding refrigerant pipe 15 via a connecting pipe 71.
The connecting pipe 71 is a cylindrical pipe, for example.
[0099] Inside the second header 70, a distributing and combining
passage 75 is formed. When the heat exchanger 50 operates as a
condenser (radiator), the distributing and combining passage 75
serves as a distributing passage that allows the refrigerant
flowing from the refrigerant pipe 15 to flow into the plurality of
heat transfer tubes 52B of the second heat exchanging unit 51B to
be distributed thereto. Further, when the heat exchanger 50
operates as an evaporator, the distributing and combining passage
75 serves as a combining passage that allows flows of refrigerant
flowing from the plurality of heat transfer tubes 52B of the second
heat exchanging unit 51B to combine together and flow into the
refrigerant pipe 15. That is, one side of the distributing and
combining passage 75 is connected to the plurality of heat transfer
tubes 52B, and the other side of the distributing and combining
passage 75 is connected to the refrigerant pipe 15.
[0100] As described above, when operating as an evaporator, the
heat exchanger 50 separately includes the first header 60 and the
second header 70, in which the distributing passages (the
distributing and combining passages 65a and 65b) and the combining
passage (the distributing and combining passage 75) are
respectively formed.
[0101] In other words, when operating as a condenser, the heat
exchanger 50 separately includes the second header 70 and the first
header 60, in which the distributing passage (the distributing and
combining passage 75) and the combining passages (the distributing
and combining passages 65a and 65b) are respectively formed.
[0102] The heat transfer tubes 52A and 52B are made of aluminum,
for example.
[0103] Further, the fins 53A and 53B are made of aluminum, for
example. The heat transfer tubes 52A and the fins 53A are joined
together by brazing, for example. The heat transfer tubes 52B and
the fins 53B are joined together by brazing, for example.
[0104] Further, the number of the heat transfer tubes 52A and the
number of the heat transfer tubes 52B are not limited to the
respective numbers thereof illustrated in FIGS. 3 and 4.
[0105] Similarly, the number of the fins 53A and the number of the
fins 53B are not limited to the respective numbers thereof
illustrated in FIGS. 3 and 4.
<Connection Between Heat Exchanging Units and Header
Units>
[0106] Connection between the heat exchanging units and the header
units of the heat exchanger 50 will be described.
[0107] FIG. 5 is a top view schematically illustrating an example
of the heat exchanger 50 installed in the heat source-side unit
100A. FIG. 6 is a schematic sectional view taken along line A-A in
FIG. 5. The connection between the heat exchanging units and the
header units will be described based on FIGS. 5 and 6. In FIG. 5, a
void arrow represents an airflow.
[0108] As illustrated in FIGS. 5 and 6, joint parts 56A are joined
to end portions 52a of the heat transfer tubes 52A near the first
header 60. A passage is formed inside each of the joint parts 56A.
One end portion of the passage has a shape following the outer
circumferential surface of the corresponding heat transfer tube
52A, and an other end portion of the passage has a circular
shape.
[0109] Further, joint parts 56B are similarly joined to end
portions 52b of the heat transfer tubes 52B near the second header
70. A passage is formed inside each of the joint parts 56B. One end
portion of the passage has a shape following the outer
circumferential surface of the corresponding heat transfer tube
52B, and an other end portion of the passage has a circular
shape.
[0110] Some of the joint parts 56A and some of the joint parts 56B
are connected by inter-column connecting parts 57. Each of the
inter-column connecting parts 57 is a cylindrical pipe bent into an
arc shape, for example.
[0111] Some of the joint parts 56A joined to the end portions 52a
of the heat transfer tubes 52A are connected to connecting pipes 62
of the first header 60. FIG. 5 illustrates the upper branching unit
60a forming the first header 60. The connecting pipes 62 connected
to the upper branching unit 60a will be described as the connecting
pipes 62a.
[0112] Some of the joint parts 56B joined to the end portions 52b
of the heat transfer tubes 52B are connected to connecting pipes 72
of the second header 70.
[0113] Each of the connecting pipes 62 and the corresponding joint
part 56A may be integrated together. Further, each of the
connecting pipes 72 and the corresponding joint part 56B may be
integrated together. Further, each of the inter-column connecting
parts 57 and the corresponding joint parts 56A and 56B may be
integrated together.
[0114] Further, FIG. 6 illustrates, as an example, the inter-column
connecting parts 57 connected to the joint parts 56A and 56B in a
tilted position. The inter-column connecting parts 57, however, may
be horizontally connected to the joint parts 56A and 56B.
<Flow of Refrigerant in Heat Exchanger 50>
[0115] FIG. 7 is a schematic diagram illustrating a flow of
refrigerant in the heat exchanger 50 installed in the heat
source-side unit 100A. FIG. 8 is a graph schematically illustrating
the transition of the state of the refrigerant in the heat
exchanger 50 installed in the heat source-side unit 100A. A flow of
refrigerant in the heat exchanger 50 will be described based on
FIGS. 7 and 8. In FIG. 7, a flow of refrigerant during the
operation of the heat exchanger 50 as a condenser is represented by
arrows (1) to (5). Further, (1) to (5) illustrated in FIG. 8
correspond to (1) to (5) in FIG. 7. Further, in FIG. 8,
temperatures of air in the heat exchanger 50 are represented by
broken lines.
[0116] The refrigerant flowing through the refrigerant pipe 15
flows into the second header 70 to be divided into a plurality of
flows in the distributing and combining passage 75, and flows into
each of the plurality of heat transfer tubes 52B of the second heat
exchanging unit 51B from the end portion 52b of the heat transfer
tube 52B (arrow (1)). In this process, the refrigerant is in the
gas state similar to the state of the refrigerant discharged from
the compressor 10 ((1) in FIG. 8). The refrigerant flowing from the
end portion 52b flows toward the other end portion of the heat
transfer tube 52B. In this process, the refrigerant exchanges heat
with the air supplied by the heat source-side fan 50A. In this
process, the refrigerant is in the superheated gas state ((2) in
FIG. 8).
[0117] The refrigerant flowing to the other end portion of the heat
transfer tube 52B flows into another heat transfer tube 52B located
thereabove via the hairpin part 54B (arrow (2)). The refrigerant
flowing from the other end portion of the heat transfer tube 52B
flows toward the end portion 52b of the heat transfer tube 52B. In
this process, too, the refrigerant exchanges heat with the air
supplied by the heat source-side fan 50A.
[0118] The refrigerant flowing to the end portion 52b of the heat
transfer tube 52B moves to the first heat exchanging unit 51A via
the inter-column connecting part 57 (arrow (3)). In this process,
the refrigerant is in the two-phase gas-liquid state ((3) in FIG.
8). The refrigerant moving to the first heat exchanging unit 51A
flows into the corresponding one of the plurality of heat transfer
tubes 52A of the first heat exchanging unit 51A from the end
portion 52a of the heat transfer tube 52A. The refrigerant flowing
from the end portion 52a flows toward the other end portion of the
heat transfer tube 52A. In this process, the refrigerant exchanges
heat with the air supplied by the heat source-side fan 50A.
[0119] The refrigerant flowing to the other end portion of the heat
transfer tube 52A flows into another heat transfer tube 52A located
therebelow via the hairpin part 54A (arrow (4)). The refrigerant
flowing from the other end portion flows toward the end portion 52a
of the heat transfer tube 52A. In this process, too, the
refrigerant exchanges heat with the air supplied by the heat
source-side fan 50A. In this process, the refrigerant is in the
subcooled state ((2) in FIG. 8). The refrigerant flowing to the end
portion 52a of the heat transfer tube 52A flows into the first
header 60 (arrow (5)). The flows of refrigerant flowing into the
first header 60 combine together in the first header 60 and flow
from the heat exchanger 50.
[0120] When the heat exchanger 50 operates as an evaporator, the
refrigerant flows from the first header 60 to the second header
70.
[0121] Further, as to the installation position of the temperature
sensor 80, which will be described later, the temperature sensor 80
may be installed at a position at which the temperature sensor 80
is capable of measuring the temperature of the refrigerant flowing
through one of the positions represented by arrow (3) in FIG. 7.
That is, the temperature sensor 80 may be installed on the
inter-column connecting part 57 connected to the joint parts 56A
and 56B at a position higher than an intermediate position in the
height direction of the heat exchanger 50. Preferably, the
temperature sensor 80 may be installed at the upper one of the
positions illustrated in of FIG. 7.
<Installation Position of Temperature Sensor 80>
[0122] In general, a refrigeration cycle apparatus has a
temperature sensor and a pressure sensor disposed at respective
predetermined locations in a refrigerant circuit to measure the
temperature and pressure, respectively, of the refrigerant
circulating through the refrigerant circuit, to thereby protect the
system of the refrigeration cycle apparatus. That is, the actuators
are controlled based on temperature information and pressure
information obtained through the measurements with the sensors. To
protect the system, therefore, it is important to reliably measure
the state of the refrigerant. There is also a refrigeration cycle
apparatus in which the pressure sensor is replaced by a temperature
sensor installed at a location through which two-phase gas-liquid
refrigerant flows, and the temperature of the refrigerant in the
two-phase state measured by the temperature sensor is converted
into the pressure of the refrigerant.
[0123] When a heat exchanger operates as a condenser, the state of
the refrigerant flowing through the heat exchanger transitions
between the superheated gas state, the two-phase state, and the
subcooled state. Therefore, it is substantially important for the
system to reliably measure the temperature of the refrigerant in
the two-phase state. Accordingly, the temperature sensor needs to
be installed at a position at which the temperature sensor is
capable of reliably measuring the refrigerant in the two-phase
state.
[0124] In the heat source-side unit 100A, therefore, the
temperature sensor 80 is installed at a position at which the
degree of subcooling is unlikely to be obtained. Specifically, as
illustrated in FIG. 5, the temperature sensor 80 is installed on an
upper portion of the inter-column connecting part 57 located
uppermost. With the temperature sensor 80 installed at this
position, the measurement of the temperature of the refrigerant in
the two-phase state in the heat exchanger 50 is improved in
reliability.
[0125] The position in the heat exchanger 50 at which the degree of
subcooling is unlikely to be obtained corresponds to a position on
the upper branching unit 60a. The position of separation between
the upper branching unit 60a and the lower branching unit 60b
corresponds to the intermediate position in the vertical direction
of the heat exchanger 50. That is, the temperature sensor 80 may be
installed on the inter-column connecting part 57 connected to the
joint parts 56A and 56B at a position higher than the intermediate
position in the height direction of the heat exchanger 50. As
illustrated in FIG. 5, however, it is preferable to install the
temperature sensor 80 on an upper portion of the inter-column
connecting part 57 located uppermost. The temperature sensor 80 may
be installed not to an upper portion of the inter-column connecting
part 57 but on a lower or lateral portion of the inter-column
connecting part 57.
[Details of First Header 60]
[0126] A specific configuration example of the first header 60 will
first be described. FIG. 9 is a longitudinal sectional view
illustrating an example of the upper branching unit 60a forming the
first header 60 of the heat exchanger 50 installed in the heat
source-side unit 100A. FIG. 10 is a perspective view illustrating
another example of the upper branching unit 60a forming the first
header 60 of the heat exchanger 50 installed in the heat
source-side unit 100A. For convenience of illustration, FIG. 9
illustrates a plate-shaped body as having a substantially uniform
thickness. Further, FIG. 9 illustrates a section cut along a flow
direction of fluid. Further, although FIG. 9 illustrates the upper
branching unit 60a, the lower branching unit 60b is similar in
configuration to the upper branching unit 60a.
[0127] As illustrated in FIG. 9, the first header 60 may be formed
as a stacking-type header including a plate-shaped body 90. The
plate-shaped body 90 is formed by alternately stacking first
plate-shaped parts 91a to 91d, which serve as bare materials, and
second plate-shaped parts 92a to 92d, which serve as clad
materials. The first plate-shaped parts 91a and 91e are stacked as
the outermost sides in a stacking direction of the plate-shaped
body 90.
[0128] In the following, the first plate-shaped parts 91a to 91e
may be collectively referred to as the first plate-shaped parts 91.
Similarly, the second plate-shaped parts 92a to 92d may be
collectively described as the second plate-shaped parts 92.
[0129] The first plate-shaped parts 91 are made of aluminum, for
example. No brazing material is applied to the first plate-shaped
parts 91. Each of the first plate-shaped parts 91 is formed with a
through-hole forming the distributing and combining passage 65. The
through-hole passes through the front surface and the back surface
of the first plate-shaped part 91. With the first plate-shaped
parts 91 and the second plate-shaped parts 92 stacked upon each
other, the through-holes formed in the first plate-shaped parts 91
function as parts of the distributing and combining passage 65.
[0130] The second plate-shaped parts 92 are made of aluminum, for
example, and are formed to be thinner than the first plate-shaped
parts 91. A brazing material is applied to at least the front
surface and the back surface of each of the second plate-shaped
parts 92. Each of the second plate-shaped parts 92 is formed with a
through-hole forming the distributing and combining passage 65. The
through-hole passes through the front surface and the back surface
of the second plate-shaped part 92. With the first plate-shaped
parts 91 and the second plate-shaped parts 92 stacked upon each
other, the through-holes formed in the second plate-shaped parts 92
function as parts of the distributing and combining passage 65.
[0131] The through-hole formed in the first plate-shaped part 91a
is connected to the connecting pipe 61a. For example, a component
such as a mouthpiece may be attached to a surface of the first
plate-shaped part 91a from which the refrigerant flows into the
first plate-shaped part 91a, and the connecting pipe 61a may be
connected to the through-hole via the component such as a
mouthpiece. Further, the inner circumferential surface of the
through-hole formed in the first plate-shaped part 91a may have a
shape that fits around the outer circumferential surface of the
connecting pipe 61a, and the connecting pipe 61a may be directly
connected to the through-hole without a component such as a
mouthpiece.
[0132] Each of the through-holes formed in the first plate-shaped
part 91e is connected to the connecting pipe 62a. For example, a
component such as a mouthpiece may be attached to a surface of the
first plate-shaped part 91e from which the refrigerant flows out
the first plate-shaped part 91e, and the connecting pipe 62a may be
connected to the through-hole via the component such as a
mouthpiece. Further, the inner circumferential surface of the
through-hole formed in the first plate-shaped part 91e may have a
shape that fits around the outer circumferential surface of the
connecting pipe 62a, and the connecting pipe 62a may be directly
connected to the through-hole without a component such as a
mouthpiece. The connecting pipe 62a may be inserted into the
through-hole in the first plate-shaped part 91e to reach the
through-hole in the first plate-shaped part 91d, to thereby connect
the connecting pipe 62a to the through-hole in the first
plate-shaped part 91e.
[0133] Each of the through-holes formed in the first plate-shaped
parts 91a and 91c passes therethrough such that a passage section
has a Z-shape, for example.
[0134] The passage section is a section of a passage cut along a
direction perpendicular to the flow of fluid.
[0135] With the first plate-shaped parts 91 and the second
plate-shaped parts 92 stacked upon each other, the through-holes
formed in the first plate-shaped parts 91 and the through-holes
formed in the second plate-shaped parts 92 communicate with each
other to form the distributing and combining passage 65. That is,
with the first plate-shaped parts 91 and the second plate-shaped
parts 92 stacked upon each other, adjacent through-holes
communicate with each other, and each of portions other than the
communicating through-holes is closed by the first plate-shaped
part 91 or the second plate-shaped part 92 adjacent to the portion,
thereby forming the distributing and combining passage 65.
[0136] FIG. 9 illustrates an example in which the distributing and
combining passage 65 has four fluid outlets for one fluid inlet.
However, the number of branches is not limited to four.
[0137] A description will be given of a flow of refrigerant in the
upper branching unit 60a when the refrigerant flows into the upper
branching unit 60a from the connecting pipe 61a.
[0138] As illustrated in FIG. 9, the refrigerant flowing through
the connecting pipe 61a flows into the upper branching unit 60a
from the through-hole in the first plate-shaped part 91a as a fluid
input. The refrigerant flows into the through-hole in the second
plate-shaped part 92a.
[0139] The refrigerant flowing into the through-hole in the second
plate-shaped part 92a flows into the center of the through-hole in
the first plate-shaped part 91b. The refrigerant flowing into the
center of the through-hole in the first plate-shaped part 91b hits
against a surface of the second plate-shaped part 92b stacked
adjacent to the first plate-shaped part 91b, and branches into
flows each flowing to an end portion of the through-hole in the
first plate-shaped part 91b. Each of the flows of refrigerant
reaching the end portion of the through-hole in the first
plate-shaped part 91b passes through the corresponding through-hole
in the second plate-shaped part 92b, and flows into the center of
the corresponding through-hole in the first plate-shaped part
91c.
[0140] The refrigerant flowing into the center of the through-hole
in the first plate-shaped part 91c hits against a surface of the
second plate-shaped part 92c stacked adjacent to the first
plate-shaped part 91c, and branches into flows each flowing to an
end portion of the through-hole in the first plate-shaped part 91c.
Each of the flows of refrigerant reaching the end portion of the
through-hole in the first plate-shaped part 91c passes through the
corresponding through-hole in the second plate-shaped part 92c, and
flows into the corresponding through-hole in the first plate-shaped
part 91d. The refrigerant flowing into the through-hole in the
first plate-shaped part 91d passes through the corresponding
through-hole in the second plate-shaped part 92d, and flows into
the corresponding heat transfer tube 52A via the connecting pipe 62
located in the through-hole in the first plate-shaped part 91e.
[0141] With the first header 60 formed as a stacking-type header,
the uniformity in distribution of the refrigerant in the first
header 60 is improved.
[0142] Although FIG. 9 illustrates an example in which the first
header 60 is formed as a stacking-type header, the first header 60
may be formed as a cylindrical header, as illustrated in FIG.
10.
[0143] A configuration example of the branching units forming the
first header 60 will now be described. FIG. 11 is a perspective
view illustrating a configuration example of the first header 60 of
the heat exchanger 50 installed in the heat source-side unit 100A.
FIG. 12 is a perspective view illustrating another configuration
example of the first header 60 of the heat exchanger 50 installed
in the heat source-side unit 100A.
[0144] As illustrated in FIG. 11, the first header 60 may be
configured with the upper branching unit 60a and the lower
branching unit 60b separated from each other. In this case, the
first header 60 may be configured with each of the upper branching
unit 60a and the lower branching unit 60b formed as a stacking-type
header or a cylindrical header. Further, the first header 60 may be
configured with one of the upper branching unit 60a and the lower
branching unit 60b formed as a stacking-type header and the other
one of the upper branching unit 60a and the lower branching unit
60b formed as a cylindrical header.
[0145] Further, as illustrated in FIG. 12, the entire first header
60 may be integrally formed with a divider 69 placed therein to
form the upper branching unit 60a and the lower branching unit 60b.
As illustrated in FIG. 12, the first header 60 may include a
plurality of dividers 69 to form an intermediate branching unit
60c. If the first header 60 is formed as a stacking-type header,
the plate-shaped body 90 may be formed with a plurality of fluid
inlets, and the distributing and combining passages 65 from the
fluid inlets to the fluid outlets may be configured not to
communicate with each other. Further, if the first header 60 is
formed as a cylindrical header, the internal space of the first
header 60 may be divided into a plurality of spaces with the
divider(s) 69, as illustrated in FIG. 12.
[0146] A description will now be given of an operation of the first
header 60 including the plurality of branching units. FIG. 13 is a
graph for illustrating the pressure loss in a header not including
a plurality of branching units. FIG. 14 is a graph for illustrating
the pressure loss in a header including a plurality of branching
units. FIG. 15 is a perspective view schematically illustrating
still another example of the heat exchanger 50 installed in the
heat source-side unit 100A. FIG. 16 is a table for illustrating
combinations of heat transfer tubes and header passages. An
operation of a header including a plurality of branching units will
be described based on FIGS. 13 to 16.
[0147] In FIGS. 13 and 14, the vertical axis represents the
pressure, and the horizontal axis represents the temperature.
Further, in FIGS. 13 and 14, "A", "B," "C," and "D" represent a
subcooling line inlet, a header inlet, a heat transfer tube inlet,
and a heat transfer tube outlet, respectively. Further, in FIG. 16,
the upper row illustrates the sectional shapes of heat transfer
tubes, and the lower row illustrates the sectional shapes of header
passages. Further, in FIG. 16, the left side illustrates a
combination of a cylindrical pipe and a header passage, and the
right side illustrates a combination of a flat tube and a header
passage.
[0148] When a heat exchanger is operated as a condenser,
refrigerant branched in a header exchanges heat with air and is
liquefied, and a liquid head for the liquefied refrigerant causes
variation in the pressure loss between paths. Specifically, the
higher a path is located, the more easily the refrigerant flows
through the path, increasing the flow rate of the refrigerant.
Meanwhile, the lower the path is located, the less easily the
refrigerant flows through the path. As illustrated in FIG. 15,
therefore, an ordinary heat exchanger operating as a condenser
subcools the refrigerant on the downstream side of the heat
transfer tubes in many cases to improve the heat exchange
performance. Downstream-side heat transfer tubes for subcooling the
refrigerant are referred to as a subcooling line (a subcooling line
55 illustrated in FIG. 15).
[0149] A case will be examined in which the subcooling line
illustrated in FIG. 15 uses heat transfer tubes (flat tubes) each
having an elliptical sectional shape illustrated on the right side
of FIG. 16.
[0150] The relational expression of the pressure loss in the flat
tube illustrated on the right side of FIG. 16 is
.DELTA.P.varies.u{circumflex over ( )}2.times.L/d.
[0151] Herein, u is "Gr/A," wherein A is ".pi.d{circumflex over (
)}2/4." Further, .DELTA.P represents the "pressure loss," u
represents the "flow velocity," L represents the "pipe length," and
d represents the "hydraulic diameter."
[0152] As illustrated on the left side of FIG. 16, in a heat
exchanger employing a combination of heat transfer tubes each
having a circular sectional shape and header passages each having a
circular sectional shape, narrow tubes such as capillaries are used
as pipes connecting the header passages and the heat transfer
tubes. Therefore, the hydraulic diameter of each of the heat
transfer tubes is greater than the hydraulic diameter of each of
distributor passages. Consequently, the heat exchanger is unlikely
to be affected by the liquid head, reducing the difference in flow
rate between an upper path and a lower path during cooling.
[0153] Meanwhile, as illustrated on the right side of FIG. 16, in a
heat exchanger employing a combination of flat tubes and header
passages each having a circular sectional shape, the header
passages and the flat tubes are connected with joint parts. A flat
tube usually has a small hydraulic diameter, such as 1 mm or less.
Therefore, the hydraulic diameter of each of the heat transfer
tubes is smaller than the hydraulic diameter of each of the
distributor passages. Consequently, the pressure loss in the header
passages is reduced, and the heat exchanger is likely to be
affected by the liquid head. That is, the heat exchanger 50 may
also employ the configuration connecting the header passages and
the flat tubes with the joint parts 56A, and thus is required to
address the pressure loss in the header passages.
[0154] The relationship between the flow rate of the refrigerant
and the degree of subcooling will be described.
[0155] It is assumed here that a relationship Gr1>Gr2 holds in
which Gr1 represents the flow rate of the refrigerant in one of a
plurality of paths in a heat exchanger, and Gr2 represents the flow
rate of the refrigerant in another one of the plurality of paths in
the heat exchanger. When it is further assumed that an exchanged
heat amount (Q) and an inlet enthalpy (Hi) are equal between the
plurality of paths, an equation
Q=Gr1.times.(Hi-Ho1)=Gr2.times.(Hi-Ho2) is established. Since the
relationship Gr1>Gr2 holds, it is understood that an outlet
enthalpy (Ho2) in the another one of the plurality of paths is
lower than an outlet enthalpy (Ho1) in the one of the plurality of
paths. That is, it is considered that the lower the flow rate of
the refrigerant is, the more likely the degree of subcooling is to
be obtained.
[0156] If a heat exchanger having a subcooling line and a header
not including a plurality of branching units is operated as an
evaporator, the pressure loss in the refrigerant passages inside
the header is increased, as illustrated in FIG. 13 (.DELTA.P2
illustrated in FIG. 13), and the temperature of the refrigerant at
the inlet of the header is higher than the temperature of air. That
is, the amount of refrigerant not evaporated is increased, thereby
reducing the heat exchange efficiency and causing inefficiency. For
example, according to heat exchangers in the past such as the heat
exchanger described in Patent Literature 1, lower heat transfer
tubes are used as the subcooling line. Therefore, the paths are
connected with narrow tubes, to thereby obtain a pressure loss and
reduce the head difference. This configuration, however, increases
the pressure loss in the refrigerant passages inside the header,
not improving the heat exchange efficiency.
[0157] Meanwhile, if a heat exchanger having a subcooling line and
a header including a plurality of branching units, such as the heat
exchanger 50, is operated as an evaporator, the pressure loss in
the refrigerant passages inside the header is reduced, as
illustrated in FIG. 14 (.DELTA.P2 illustrated in FIG. 14), and the
temperature of the refrigerant at the inlet of the header is lower
than the temperature of air. That is, the entire heat exchanger is
capable of evaporating the refrigerant, improving the heat exchange
efficiency.
[0158] In the heat source-side unit 100A, therefore, the first
header 60 of the heat exchanger 50 is formed by two or more
branching units arranged in the vertical direction. The heat
source-side unit 100A, therefore, is capable of mitigating the head
difference between the paths due to the pressure loss in the heat
transfer tubes 52A in the first header 60, and thus reducing the
difference in the flow rate of the refrigerant between all of the
heat transfer tubes. The heat source-side unit 100A is therefore
capable of performing heat exchange in the entire heat exchanger
50, thereby improving the heat exchange efficiency.
[0159] Further, according to the heat source-side unit 100A, even
if the distributor 85 as illustrated in FIG. 4 is used, the
branching depends on the number of branching units forming the
first header 60. It is therefore possible to suppress an increase
in the size of the body of the distributor and an increase in the
number of pipes connected to the distributor 85. Accordingly, there
is no need to unnecessarily increase the internal space of the heat
source-side unit 100A, allowing effective use of space.
<Effects of Heat Source-Side Unit 100A and Refrigeration Cycle
Apparatus 100>
[0160] As described above, the heat source-side unit 100A includes
the heat exchanger 50 that includes the plurality of heat
exchanging units (the first heat exchanging unit 51A and the second
heat exchanging unit 51B) and the temperature sensor 80 that
measures the temperature of the refrigerant flowing through the
heat exchanger 50. The heat exchanger 50 includes: the first header
60 connected to the first heat exchanging unit 51A, which is at
least one of the plurality of heat exchanging units, and including
the plurality of branching units arranged in the vertical direction
(the upper branching unit 60a and the lower branching unit 60b);
the second header 70 connected to the second heat exchanging unit
51B, which is at least one of rest of the plurality of heat
exchanging units; and the plurality of inter-column connecting
parts 57 that connect parts of the heat transfer tubes 52A forming
the first heat exchanging unit 51A and parts of the heat transfer
tubes 52B forming the second heat exchanging unit 51B. The
temperature sensor 80 is installed on the inter-column connecting
part 57 included in the plurality of inter-column connecting parts
57 and located higher than the intermediate position in the
vertical direction of the heat exchanger 50.
[0161] According to the heat source-side unit 100A, therefore, the
temperature of the two-phase gas-liquid refrigerant flowing through
the inter-column connecting part 57 is measured. It is therefore
possible to accurately measure the temperature of the two-phase
refrigerant used in controlling the actuators included in the
refrigeration cycle apparatus 100, and to perform efficient system
protection.
[0162] Further, according to the heat source-side unit 100A, the
temperature sensor 80 is installed on the inter-column connecting
part 57 located uppermost among the plurality of inter-column
connecting parts 57. It is therefore possible to measure the
temperature of the refrigerant at the inter-column connecting part
57 disposed at a position at which the degree of subcooling is
unlikely to be obtained. Accordingly, the temperature of the
two-phase refrigerant is further reliably measured.
[0163] Further, in the heat source-side unit 100A, each of the heat
transfer tubes 52A forming the first heat exchanging unit 51A has
the hairpin part 54A on the end portion of the heat transfer tube
52A opposite to the end portion of the heat transfer tube 52A near
the first header 60. Each of the heat transfer tubes 52B forming
the second heat exchanging unit 51B has the hairpin part 54B on the
end portion of the heat transfer tube 52B opposite to the end
portion of the heat transfer tube 52B near the second header 70.
The inter-column connecting parts 57 are disposed near the first
header 60 and the second header 70.
[0164] According to the heat source-side unit 100A, therefore, it
is possible to install the temperature sensor 80 on the
inter-column connecting part 57 without employing a complicated
configuration.
[0165] Further, according to the heat source-side unit 100A, the
first header 60 is a stacking-type header having the plurality of
plate-shaped parts (the first plate-shaped parts 91 and the second
plate-shaped parts 92) stacked upon each other. Accordingly, the
uniformity in distribution of the refrigerant is improved.
[0166] Further, according to the heat source-side unit 100A, the
heat transfer tubes (the heat transfer tubes 52A and 52B) are flat
tubes. Accordingly, the heat exchange efficiency of each of the
heat exchanging units is improved.
[0167] Further, the heat source-side unit 100A includes the heat
source-side fan 50A that supplies air to the heat exchanger 50, and
the first heat exchanging unit 51A and the second heat exchanging
unit 51B are arranged side by side in the passing direction of the
air supplied by the heat source-side fan 50A. Accordingly, there is
no increase in the size of the heat exchanger 50.
[0168] Further, the refrigeration cycle apparatus 100 includes the
above-described heat source-side unit 100A and the load-side unit
100B connected to the heat source-side unit 100A, and thus has all
of the effects of the heat source-side unit 100A. That is,
according to the refrigeration cycle apparatus 100, the measurement
of the temperature of the two-phase gas-liquid refrigerant is
improved in reliability. Accordingly, the control of the actuators
is optimized, and efficient system protection is realized.
* * * * *