Technical Field
[0001] 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 Art
[0002] 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.
[0003] 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).
Citation List
Patent Literature
[0004] Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2013-231527
Summary of Invention
Technical Problem
[0005] 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.
[0006] 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.
[0007] 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.
Solution to Problem
[0008] 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.
[0009] A refrigeration cycle apparatus according to an embodiment of the present invention
includes the above-described heat source-side unit.
Advantageous Effects of Invention
[0010] 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.
[0011] 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
[0012]
[Fig. 1] 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.
[Fig. 2] 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.
[Fig. 3] 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.
[Fig. 4] 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.
[Fig. 5] 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.
[Fig. 6] Fig. 6 is a schematic sectional view taken along line A-A in Fig. 5.
[Fig. 7] 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.
[Fig. 8] 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.
[Fig. 9] 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.
[Fig. 10] 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.
[Fig. 11] 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.
[Fig. 12] 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.
[Fig. 13] Fig. 13 is a graph for illustrating a pressure loss in a header not including
a plurality of branching units.
[Fig. 14] Fig. 14 is a graph for illustrating a pressure loss in a header including
a plurality of branching units.
[Fig. 15] 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.
[Fig. 16] Fig. 16 is a table for illustrating combinations of heat transfer tubes
and header passages.
Description of Embodiments
[0013] A heat source-side unit and a refrigeration cycle apparatus according to the present
invention will be described below with the drawings.
[0014] 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.
[0015] 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.
[0016] 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>
[0017] 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.
[0018] As illustrated in Fig. 1, the refrigeration cycle apparatus 100 includes a heat source-side
unit 100A and a load-side unit 100B.
[0019] 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.
[0020] 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]
[0021] 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.
[0022] 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.
[0023] 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.
[0024] 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.
[0025] 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.
[0026] The heat exchanger 50 will be described in detail later.
[0027] 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.
[0028] 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.
[0029] 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.
[0030] 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.
[0031] 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]
[0032] 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.
[0033] The load-side unit 100B includes the load-side heat exchanger 13 and the load-side
fan 13A.
[0034] 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.
[0035] 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.
[0036] 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.
[0037] 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.
[0038] Further, the expansion device 12 may be included in the load-side unit 100B.
[Refrigerant Usable in Refrigeration Cycle Apparatus 100]
[0039] The refrigerant used in the refrigeration cycle apparatus 100 includes a non-azeotropic
refrigerant mixture, a near-azeotropic refrigerant mixture, and single refrigerant.
[0040] 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.
[0041] 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.
[0042] 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>
[0043] Operations performed by the refrigeration cycle apparatus 100 will be described as
well as of flows of the refrigerant.
[0044] 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.
[0045] 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]
[0046] 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.
[0047] 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.
[0048] 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
51, 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.
[0049] 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]
[0050] 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.
[0051] 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.
[0052] 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.
[0053] 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>
[0054] Details of the heat source-side unit 100A according to Embodiment of the present
invention will now be described.
[0055] 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.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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.
[0060] The first heat exchanging unit 51A and the second heat exchanging unit 51 B are arranged
side by side along the passing direction of the air passing through the heat exchanger
50 (the void arrow in the drawing).
[0061] 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).
[0062] 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]
[0063] 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.
[0064] 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.
[0065] 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.
[0066] 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]
[0067] 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.
[0068] 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.
[0069] 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.
[0070] 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.
[0071] 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]
[0072] 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.
[0073] Herein, the vertical direction means the vertical direction of the heat exchanger
50 as installed in the heat source-side unit 100A.
[0074] 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.
[0075] As illustrated in Fig. 4, the upper branching unit 60a is connected to a refrigerant
pipe 15a via a connecting pipe 61a.
[0076] Further, the lower branching unit 60b is connected to a refrigerant pipe 15b via
a connecting pipe 61b.
[0077] Further, the refrigerant pipes 15a and 15b are connected to the corresponding refrigerant
pipe 15 via a distributor 85.
[0078] The connecting pipes 61a and 61b are cylindrical pipes, for example.
[0079] 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.
[0080] 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]
[0081] 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.
[0082] 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.
[0083] 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.
[0084] 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.
[0085] 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.
[0086] The heat transfer tubes 52A and 52B are made of aluminum, for example.
[0087] Further, the fins 53A and 53B are made of aluminum, for example. The heat transfer
tubes 4 and the fins 5 are joined together by brazing, for example.
[0088] 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.
[0089] 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>
[0090] Connection between the heat exchanging units and the header units of the heat exchanger
50 will be described.
[0091] 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.
[0092] 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.
[0093] 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.
[0094] 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.
[0095] 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.
[0096] 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.
[0097] 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.
[0098] 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>
[0099] 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.
[0100] 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).
[0101] 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.
[0102] 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.
[0103] 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.
[0104] When the heat exchanger 50 operates as an evaporator, the refrigerant flows from
the first header 60 to the second header 70.
[0105] 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>
[0106] 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.
[0107] 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.
[0108] 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.
[0109] 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]
[0110] 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.
[0111] 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.
[0112] 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.
[0113] 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.
[0114] 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.
[0115] 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.
[0116] 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 into
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.
[0117] 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.
[0118] The passage section is a section of a passage cut along a direction perpendicular
to the flow of fluid.
[0119] 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.
[0120] 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.
[0121] 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.
[0122] 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.
[0123] 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 92d 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.
[0124] 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.
[0125] 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.
[0126] 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.
[0127] 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.
[0128] 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.
[0129] 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.
[0130] 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.
[0131] 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.
[0132] 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).
[0133] 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.
[0134] The relational expression of the pressure loss in the flat tube illustrated on the
right side of Fig. 16 is ΔP∝u^2 × L/d.
[0135] Herein, u is "Gr/A," wherein A is "πd^2/4." Further, ΔP represents the "pressure
loss," u represents the "flow velocity," L represents the "pipe length," and d represents
the "hydraulic diameter."
[0136] 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.
[0137] 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.
[0138] The relationship between the flow rate of the refrigerant and the degree of subcooling
will be described.
[0139] 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 × (Hi - Ho1) = Gr2 × (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.
[0140] 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 (ΔP2 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.
[0141] 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 (ΔP2 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.
[0142] 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.
[0143] 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 1000>
[0144] 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 51 B) 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.
[0145] 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.
[0146] 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.
[0147] 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.
[0148] 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.
[0149] 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.
[0150] 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.
[0151] 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.
[0152] 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.
Reference Signs List
[0153] 4 heat transfer tube 5 fin 10 compressor 11 flow switching device 12 expansion device
13 load-side heat exchanger 13A load-side fan 15 refrigerant pipe 15a refrigerant
pipe 15b refrigerant pipe 40 controller 50 heat exchanger 50A heat source-side fan
51 load-side heat exchanger 51A first heat exchanging unit 51B second heat exchanging
unit 52A heat transfer tube 52B heat transfer tube 52a end portion 52b end portion
53A fin 53B fin 54A hairpin part 54B hairpin part 55 subcooling line 56A joint part
56B joint part 57 inter-column connecting part 60 first header 60a upper branching
unit 60b lower branching unit 60c intermediate branching unit 61a connecting pipe
61b connecting pipe 62 connecting pipe 62a connecting pipe 65 distributing and combining
passage 65a distributing and combining passage 65b distributing and combining passage
69 divider 70 second header 71 connecting pipe 72 connecting pipe 75 distributing
and combining passage 80 temperature sensor 85 distributor 90 plate-shaped body 91
first plate-shaped part 91a first plate-shaped part 91b first plate-shaped part 91c
first plate-shaped part 91d first plate-shaped part 91e first plate-shaped part 92
second plate-shaped part 92a second plate-shaped part 92b second plate-shaped part
92c second plate-shaped part 92d second plate-shaped part 100 refrigeration cycle
apparatus 100A heat source-side unit 100B load-side unit