FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
HEAT EXCHANGER AND REFRIGERATION CYCLE DEVICE;
MITSUBISHI ELECTRIC CORPORATION, A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3, MARUNOUCHI
2-CHOME, CHIYODA-KU, TOKYO 100-8310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE INVENTION
AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
DESCRIPTION
5 Technical Field
[0001]
The present technology relates to a heat exchanger and a refrigeration cycle
device. Particularly, the present technology relates to a heat exchanger that
exchanges heat while distributing refrigerant.
10 Background Art
[0002]
In recent years, a heat exchanger for an air-conditioning device uses heat
transfer tubes that have become increasingly thinner to reduce the amount of refrigerant
and improve performance of the heat exchanger. While using the heat transfer tubes
15 that have become increasingly thinner, the heat exchanger has an increased number of
passes (the number of branches) to minimize the increase in pressure loss of
refrigerant. Heat exchangers using a header refrigerant distributor have been
developed to cope with this multi-branch distribution (see, for example, Patent Literature
1).
20 Citation List
Patent Literature
[0003]
Patent Literature 1: Japanese Patent Publication No. 5679084
Summary of Invention
25 Technical Problem
[0004]
The header refrigerant distributor unevenly distributes gas refrigerant with a
larger amount on the upper side due to an inertial force. Due to this uneven
distribution, when operating as an evaporator, the heat exchanger tends to exhibit
30 degraded evaporator performance. To prevent the evaporator performance from being
3
degraded, when the heat exchanger operates as an evaporator, a counter flow is
formed such that refrigerant flows in a direction opposite to the airflow direction in a
section of the heat exchanger with a greater number of tube layers than in the other
sections. In contrast, when the heat exchanger operates as a condenser, refrigerant
5 flows in the heat exchanger in a direction reverse to the refrigerant flow direction when
the heat exchanger operates as an evaporator. Thus, when the heat exchanger
operates as a condenser, a parallel flow is formed such that refrigerant flows in a
direction parallel to the airflow direction. Compared to the counter flow, the parallel
flow cannot ensure a sufficient temperature difference between refrigerant and air, and
10 this results in degradation in condensation performance of the heat exchanger.
[0005]
The present disclosure has been achieved to solve the above problems, and it is
an object of the present disclosure to provide a heat exchanger that can improve its
heat exchange performance, and a refrigeration cycle device.
15 Solution to Problem
[0006]
A heat exchanger according to one embodiment of the present disclosure
includes: a heat exchange portion in which a plurality of heat transfer tubes, in which
refrigerant flows, are arranged in a height direction, the plurality of heat transfer tubes
20 being configured to exchange heat between the refrigerant and air; a turn-back portion
to which one end of each of the plurality of heat transfer tube is connected and which is
configured to allow the refrigerant to flow between two rows of heat exchange portions
arranged in an airflow direction, one of the two rows of heat exchange portions being
the heat exchange portion and arranged on an airflow upstream side, an other of the
25 two rows of heat exchange portions being the heat exchange portion and arranged on
an airflow downstream side; and a plurality of distribution merge portions to each of
which the other end of the heat transfer tube of the heat exchange portion of each row
is connected, and which is configured to distribute the refrigerant to the heat transfer
tube or merge refrigerant flows from the heat exchange portions, the plurality of heat
30 transfer tubes of the heat exchange portion being grouped into, in order from an upper
4
side in the height direction, a main heat exchange portion, a first auxiliary heat
exchange portion having fewer number of the heat transfer tubes than those of the main
heat exchange portion, and a second auxiliary heat exchange portion having fewer
number of the heat transfer tubes than those of the first auxiliary heat exchange portion,
5 and being configured to, when the heat exchanger serves as a condenser, allow the
refrigerant to flow through the heat exchanger in order of the main heat exchange
portion of the airflow downstream side row, the main heat exchange portion of the
airflow upstream side row, the first auxiliary heat exchange portion of the airflow
upstream side row, the first auxiliary heat exchange portion of the airflow downstream
10 side row, the second auxiliary heat exchange portion of the airflow downstream side
row, and the second auxiliary heat exchange portion of the airflow upstream side row,
and allow the refrigerant to flow out of the heat exchanger.
[0007]
A refrigeration cycle device according to another embodiment of the present
15 disclosure includes the heat exchanger described above to serve at least as a
condenser.
Advantageous Effects of Invention
[0008]
According to one embodiment of the present disclosure, when the heat
20 exchanger serves as a condenser, a flow of refrigerant in the main heat exchange
portion and a flow of air passing through the heat exchanger form a counter flow to
exchange heat between the upstream side of the refrigerant in the main heat exchange
portion and the downstream side of the air, and exchange heat between the
downstream side of the refrigerant in the main heat exchange portion and the upstream
25 side of the air. Due to this configuration, the heat exchanger can maintain a sufficient
temperature difference between refrigerant and air to effectively exchange heat
between them throughout the entire refrigerant flow passage, and can consequently
improve the heat transfer performance of the heat exchanger.
Brief Description of Drawings
30 [0009]
5
[Fig. 1] Fig. 1 illustrates the configuration of an air-conditioning device according
to Embodiment 1.
[Fig. 2] Fig. 2 schematically illustrates the configuration of a heat exchanger 1
according to Embodiment 1.
5 [Fig. 3] Fig. 3 is an explanatory view illustrating each part of a heat exchange
portion 10 in the heat exchanger 1 according to Embodiment 1.
[Fig. 4] Fig. 4 schematically illustrates variations in the temperatures of air and
refrigerant in the heat exchanger 1 according to Embodiment 1 when the heat
exchanger 1 serves as a condenser.
10 [Fig. 5] Fig. 5 schematically illustrates variations in the temperatures of air and
refrigerant in the heat exchanger 1 according to Embodiment 1 when the heat
exchanger 1 serves as an evaporator.
[Fig. 6] Fig. 6 schematically illustrates variations in the temperatures of air and
refrigerant in the heat exchanger 1 according to Embodiment 2 when the heat
15 exchanger 1 serves as an evaporator.
[Fig. 7] Fig. 7 is an explanatory view illustrating allocation of flat heat transfer
tubes 14 in the heat exchanger 1 according to Embodiment 3.
[Fig. 8] Fig. 8 schematically illustrates the configuration of the heat exchanger 1
according to Embodiment 4.
20 [Fig. 9] Fig. 9 illustrates an example of the configuration of a layered distributor 17
according to Embodiment 4.
Description of Embodiments
[0010]
Hereinafter, a heat exchanger and a refrigeration cycle device according to the
25 embodiments will be described with reference to the drawings and the like. In the
drawings below, like reference signs denote the like or corresponding components, and
are common throughout the entire descriptions of the embodiments described below. In
addition, the relationship of sizes of the constituent parts in the drawings may differ from
that of actual ones. Furthermore, in the cross-sectional view, hatching is omitted in
30 some of the drawings and devices in view of visibility. The forms of the constituent
6
elements represented throughout the entire specification are merely examples, and do
not intend to limit the constituent elements to the forms described in the specification. In
particular, the combination of constituent elements is not limited to only the combination
in each embodiment, and the constituent elements described in one embodiment can be
5 applied to another embodiment. The upper side in the drawings is described as "up,"
while the lower side in the drawings is described as "down." Furthermore, the level of
the pressure and temperature is not particularly determined in relation to an absolute
value, but is determined relative to the conditions or operation of a device or the like.
When it is not necessary to distinguish or specify a plurality of devices of the same type
10 that are distinguished from each other by subscripts, the subscripts may be omitted.
[0011]
Embodiment 1

Fig. 1 illustrates the configuration of an air-conditioning device according to
15 Embodiment 1. The air-conditioning device is now explained as an example of the
refrigeration cycle device including a heat exchanger in Embodiment 1.
[0012]
As illustrated in Fig. 1, the air-conditioning device in Embodiment 1 includes an
outdoor unit 200, an indoor unit 100, and two refrigerant pipes 300. The outdoor unit
20 200 includes a compressor 210, a four-way valve 220, and an outdoor heat exchanger
230. The indoor unit 100 includes an indoor heat exchanger 110 and an expansion
valve 120. The compressor 210, the four-way valve 220, the outdoor heat exchanger
230, the indoor heat exchanger 110, and the expansion valve 120 are connected by the
refrigerant pipes 300 to form a refrigerant circuit. In the air-conditioning device in
25 Embodiment 1, one outdoor unit 200 and one indoor unit 100 are connected by pipes.
However, the number of outdoor units 200 and the number of indoor units 100 to be
connected to each other are not limited to this example.
[0013]
The indoor unit 100 includes an indoor air-sending device 130 in addition to the
30 indoor heat exchanger 110 and the expansion valve 120. The expansion valve 120
7
that is an expansion device or other device reduces the pressure of refrigerant and
expands the refrigerant. When the expansion valve 120 is made up of, for example, an
electronic expansion valve, the expansion valve 120 adjusts its opening degree based
on an instruction provided by a controller (not illustrated) or other device. The indoor
5 heat exchanger 110 exchanges heat between refrigerant and air in a room that is an airconditioned space. For example, during heating operation, the indoor heat exchanger
110 functions as a condenser, and condenses and liquefies the refrigerant. During
cooling operation, the indoor heat exchanger 110 functions as an evaporator, and
evaporates and vaporizes the refrigerant. The indoor air-sending device 130 allows
10 the air in the room to pass through the indoor heat exchanger 110, and supplies the air
having passed through the indoor heat exchanger 110 to the room.
[0014]
The outdoor unit 200 in Embodiment 1 includes devices forming the refrigerant
circuit, such as the compressor 210, the four-way valve 220, the outdoor heat
15 exchanger 230, and an accumulator 240. The outdoor unit 200 includes an outdoor
air-sending device 250. The compressor 210 compresses suctioned refrigerant and
discharges the compressed refrigerant. The compressor 210 is, for example, a scroll
compressor, a reciprocating compressor, or a vane compressor. For example, the
compressor 210 may allow an inverter circuit to optionally change the operational
20 frequency to change the capacity of the compressor 210, although the configuration of
the compressor 210 is not particularly limited.
[0015]
For example, the four-way valve 220 that serves as a flow switching device is a
valve to change the flow direction of refrigerant depending on cooling operation or
25 heating operation. When heating operation is performed, the four-way valve 220
connects the discharge side of the compressor 210 to the indoor heat exchanger 110,
while connecting the suction side of the compressor 210 to the outdoor heat exchanger
230. When cooling operation is performed, the four-way valve 220 connects the
discharge side of the compressor 210 to the outdoor heat exchanger 230, while
30 connecting the suction side of the compressor 210 to the indoor heat exchanger 110.
8
A case where the four-way valve 220 is used is described as an example, however, the
flow switching device is not limited to this case. For example, a plurality of two-way
valves or other valves may be combined to form the flow switching device. The
accumulator 240 is installed on the suction side of the compressor 210. The
5 accumulator 240 allows refrigerant in gas form (hereinafter, referred to as "gas
refrigerant") to pass through the accumulator 240, while accumulating refrigerant in
liquid form (hereinafter, referred to as "liquid refrigerant") in the accumulator 240.
[0016]
The outdoor heat exchanger 230 exchanges heat between refrigerant and outdoor
10 air. Refrigerant is fluid to serve as a heat exchange medium for the outdoor heat
exchanger 230. The outdoor heat exchanger 230 in Embodiment 1 functions as an
evaporator during heating operation, and evaporates and vaporizes the refrigerant. In
contrast, during cooling operation, the outdoor heat exchanger 230 functions as a
condenser and a subcooling device, and condenses and liquefies the refrigerant to be
15 subcooled. The outdoor heat exchanger 230 in Embodiment 1 includes heat
exchangers 1, each of which includes a heat exchange portion 10 as will be described
later. The heat exchanger 1 will be described later in detail. The outdoor air-sending
device 250 is driven to allow air from the outside of the outdoor unit 200 to pass through
the outdoor heat exchanger 230 to form a flow of air that flows out of the outdoor unit 200.
20 [0017]

Next, operation of each device in the air-conditioning device is described based
on the flow of refrigerant. First, operation of each device in the refrigerant circuit during
heating operation is described based on the flow of refrigerant. The solid arrows in
25 Fig. 1 show the flow of refrigerant during heating operation. High-temperature highpressure gas refrigerant, compressed by and discharged from the compressor 210,
passes through the four-way valve 220, and then flows into the indoor heat exchanger
110. While passing through the indoor heat exchanger 110, the gas refrigerant
exchanges heat with air in, for example, an air-conditioned space, and thereby
30 condenses into liquid. The refrigerant having condensed into liquid passes through the
9
expansion valve 120. When the refrigerant passes through the expansion valve 120,
the pressure of the refrigerant is reduced. The refrigerant, reduced in pressure by the
expansion valve 120 and brought into a two-phase gas-liquid state, passes through the
outdoor heat exchanger 230. In the outdoor heat exchanger 230, the refrigerant
5 exchanges heat with outdoor air delivered from the outdoor air-sending device 250, and
thereby evaporates into gas. The gas refrigerant passes through the four-way valve
220 and the accumulator 240, and then is suctioned into the compressor 210 again. In
the manner as described above, refrigerant of the air-conditioning device circulates, and
thus the air-conditioning device performs heating-related air conditioning.
10 [0018]
Next, cooling operation is described. The dotted arrows in Fig. 1 show the flow
of refrigerant during cooling operation. High-temperature high-pressure gas
refrigerant, compressed by and discharged from the compressor 210, passes through
the four-way valve 220, and then flows into the outdoor heat exchanger 230. The
15 refrigerant passes through the outdoor heat exchanger 230, exchanges heat with
outdoor air supplied by the outdoor air-sending device 250, and thereby condenses into
liquid. The heat exchanger 1 will be described later. The liquid refrigerant passes
through the expansion valve 120. When passing through the expansion valve 120, the
subcooled refrigerant is reduced in pressure and brought into a two-phase gas-liquid
20 state. This refrigerant, reduced in pressure by the expansion valve 120 and brought
into a two-phase gas-liquid state, then passes through the indoor heat exchanger 110.
In the indoor heat exchanger 110, the refrigerant, having exchanged heat with air in, for
example, the air-conditioned space and thereby evaporated into gas, passes through
the four-way valve 220, and is suctioned into the compressor 210 again. In the
25 manner as described above, refrigerant of the air-conditioning device circulates, and
thus the air-conditioning device performs cooling-related air conditioning.
[0019]

Fig. 2 schematically illustrates the configuration of the heat exchanger 1
30 according to Embodiment 1. Fig. 3 is an explanatory view illustrating each part of the
10
heat exchange portion 10 in the heat exchanger 1 according to Embodiment 1. The
heat exchanger 1 according to Embodiment 1 is included in the outdoor heat exchanger
230. However, the heat exchanger 1 is not limited to being included in the outdoor
heat exchanger 230, but may be included in the indoor heat exchanger 110. The heat
5 exchanger 1 is a corrugated-fin and tube heat exchanger that is a parallel pipe heat
exchanger. The heat exchanger 1 includes two distribution headers 11 (a distribution
header 11A and a distribution header 11B) serving as a distribution merge portion, a
turn-back header 13 serving as a turn-back portion, and the heat exchange portion 10
including a plurality of flat heat transfer tubes 14 and a plurality of corrugated fins 15.
10 [0020]
In the heat exchanger 1 in Embodiment 1, the two distribution headers 11 are
located separately from the turn-back header 13 on either the left or right side. In Fig.
3, the turn-back header 13 is positioned on the right side, while the two distribution
headers 11 are positioned on the left side relative to the turn-back header 13.
15 However, the distribution headers 11 may be positioned on the right side, while the turnback header 13 may be positioned on the left side. In the explanations below, the updown direction in Figs. 2 and 3 is defined as a height direction. The right-left direction
in which the distribution headers 11 and the turn-back header 13 are located is defined
as a horizontal direction. The direction in which the outdoor air-sending device 250
20 allows air to flow, shown by the dotted arrow in Fig. 2, is defined as a depth direction.
[0021]
As illustrated in Fig. 3, between the two distribution headers 11 and the turn-back
header 13, the plurality of flat heat transfer tubes 14 are arranged in the height direction
to be perpendicular to the distribution headers 11 and the turn-back header 13 with the
25 flat surfaces of the flat heat transfer tubes 14 facing parallel to each other. In the heat
exchanger 1 in Embodiment 1, groups of the plurality of flat heat transfer tubes 14 are
arranged in two rows in the depth direction that is the front-rear direction. One row of a
group of the flat heat transfer tubes 14 is connected to a single distribution header 11.
Each of the flat heat transfer tubes 14 serves as a flow passage of refrigerant. In the
30 heat exchanger in Embodiment 1, the number of the flat heat transfer tubes 14 is equal
11
in each row group. The number of the flat heat transfer tubes 14 is equal as described
above, so that the flat heat transfer tubes 14 are equally spaced from each other,
thereby not to interfere with the passage of air. In addition, the heat exchanger 1 can
be easily manufactured. One of the two rows of the flat heat transfer tubes 14,
5 arranged on the airflow upstream side relative to the direction in which air passes
through the heat exchanger 1, is defined as "airflow upstream side row," while the other
row arranged on the airflow downstream side is defined as "airflow downstream side
row." An example in which the flat heat transfer tubes 14 are arranged in two rows is
described below.
10 [0022]
The distribution headers 11 that are devices serving as a distribution merge
portion are connected by pipes to other devices that make up the refrigeration cycle
device. Each of the distribution headers 11 is a pipe serving as a refrigerant distributor
to allow refrigerant to flow into and out of the heat exchanger 1, and divide and
15 distribute the refrigerant or merge refrigerant flows. The refrigerant is fluid serving as a
heat exchange medium. While the distribution headers 11 have a circular cylindrical
shape, the distribution headers 11 are not limited to having a particular shape. The
distribution headers 11 respectively include refrigerant inlet/outlet pipes 12 (a refrigerant
inlet/outlet pipe 12A and a refrigerant inlet/outlet pipe 12B) through which refrigerant
20 flows in from and out to the outside. When the heat exchanger 1 serves as a
condenser, refrigerant flows into the heat exchanger 1 through the refrigerant inlet/outlet
pipe 12A, and flows out through the refrigerant inlet/outlet pipe 12B. In contrast, when
the heat exchanger 1 serves as an evaporator, refrigerant flows into the heat exchanger
1 through the refrigerant inlet/outlet pipe 12B, and flows out through the refrigerant
25 inlet/outlet pipe 12A. The interior of the distribution header 11 is partitioned by a
plurality of baffles (not illustrated) into a plurality of spaces. The interior of the
distribution header 11 is divided into a plurality of spaces, and thus the heat exchanger
1 can be divided into a plurality of regions. The region refers to a group of the flat heat
transfer tubes 14, in each of which refrigerant flows in the same direction. The baffles
30 partition the interior of the distribution header 11, so that a plurality of the flat heat
12
transfer tubes 14 can be grouped into a single region. The regions in Embodiment 1
will be described later. Connection pipes 16 connect the spaces, separated from each
other inside the distribution header 11, from the outside. Each of the connection pipes
16 not only connects the spaces inside the distribution header 11 on a one-to-one basis,
5 but can also branch off on one side to connect one of the spaces inside the distribution
header 11 to a plurality of the spaces.
[0023]
The turn-back header 13 serves as a bridge configured to merge refrigerant flows
from one row of a group of the flat heat transfer tubes 14, and then divide the refrigerant
10 into the other row of a group of the flat heat transfer tubes 14 to allow the refrigerant to
flow out. In the turn-back header 13, baffles (not illustrated) are also installed at least at
positions corresponding to the positions of the baffles in the distribution headers 11 to
divide the interior of the turn-back header 13 into a plurality of spaces. For example,
baffles may be installed inside the turn-back header 13 corresponding to the respective
15 flat heat transfer tubes 14. Particularly, between the main heat exchange portion 10A of
the airflow upstream side row and the main heat exchange portion 10A of the airflow
downstream side row, the interior of the turn-back header 13 may be divided into spaces
in a one-to-one correspondence with their respective flat heat transfer tubes 14. The
main heat exchange portions 10A of the airflow upstream side row and the airflow
20 downstream side row will be described later. In this case, in the turn-back header 13,
refrigerant flows are not merged, or the refrigerant is not divided into flows. There is a
case where the flat heat transfer tubes 14 in the heat exchange portion 10 of the airflow
upstream side row are brought into one-to-one correspondence with the flat heat transfer
tubes 14 in the heat exchange portion 10 of the airflow downstream side row. In that
25 case, individual connection pipes or the like can be used to connect the flat heat transfer
tubes 14 corresponding to each other.
[0024]
Each of the flat heat transfer tubes 14 has an elongated shape in cross-section in
which the outer surface on the longitudinal side of the elongated shape along the depth
30 direction that is an air flow direction is flat, while the outer surface on the relatively short
13
side of the elongated shape perpendicular to the longitudinal direction is curved. Each
of the flat heat transfer tubes 14 in Embodiment 1 is a multi-hole flat heat transfer tube
having a plurality of holes serving as a flow passage of refrigerant inside the tube. In
Embodiment 1, since the holes of the flat heat transfer tubes 14 serve as a flow
5 passage extending between the distribution headers 11 and the turn-back header 13,
these holes are formed in the horizontal direction. As described above, the flat heat
transfer tubes 14 are aligned with equal spacing in the height direction with their outer
surfaces on the longitudinal side facing each other. In the process of manufacturing
the heat exchange portion 10 in Embodiment 1, each of the flat heat transfer tubes 14 is
10 inserted into an insertion hole (not illustrated) formed on the distribution header 11 and
an insertion hole (not illustrated) formed on the turn-back header 13 to be brazed and
joined to the distribution header 11 and the turn-back header 13. Examples of the
brazing material to be used include an aluminum-containing brazing material. With this
brazing, the inside of each of the flat heat transfer tubes 14 communicates with the
15 distribution header 11 and the turn-back header 13.
[0025]
The corrugated fins 15 are located between the opposite flat surfaces of the flat
heat transfer tubes 14 aligned in a row. The corrugated fins 15 are located to increase
the heat transfer area between refrigerant and outside air. Each of the corrugated fins
20 15 is formed by corrugating a plate material into a wavy shape in which the plate
material is folded in a zigzag pattern with a series of alternate crest folds and valley
folds. The folded portions of protrusions and recesses formed into a wavy shape are
the peaks of the wavy shape. In Embodiment 1, the peaks of the corrugated fins 15
are arranged along the height direction. Each of the corrugated fins 15 is in surface
25 contact at the peaks of the wavy shape with the flat surfaces of the flat heat transfer
tubes 14. The contact portions are brazed and joined to each other by using a brazing
material. The plate material for the corrugated fins 15 is made of, for example,
aluminum alloy. The surface of the plate material is coated with a layer of brazing
material. The coating layer of brazing material is, for example, based on a brazing
30 material containing aluminum silicon-based aluminum.
14
[0026]
In the heat exchange portion 10 of the heat exchanger 1 in Embodiment 1, when
the heat exchange portion 10 is used as a condenser, high-temperature high-pressure
refrigerant flows through the refrigerant flow passages inside the flat heat transfer tubes
5 14. When the heat exchange portion 10 is used as an evaporator, low-temperature
low-pressure refrigerant flows through the refrigerant flow passages inside the flat heat
transfer tubes 14.
[0027]
The regions mentioned above are now described. In Embodiment 1, the baffles
10 installed inside the distribution headers 11 and the turn-back header 13 divide the flat
heat transfer tubes 14 of the airflow upstream side row into regions, and divide the flat
heat transfer tubes 14 of the airflow downstream side row into regions. The regions
are the main heat exchange portion 10A, a first auxiliary heat exchange portion 10B,
and a second auxiliary heat exchange portion 10C. The uppermost region is defined
15 as the main heat exchange portion 10A. The region lower than the main heat
exchange portion 10A is defined as the first auxiliary heat exchange portion 10B. The
region lower than the first auxiliary heat exchange portion 10B is defined as the second
auxiliary heat exchange portion 10C. The number of the flat heat transfer tubes 14
grouped together in each region of the heat exchanger 1 in Embodiment 1 has the
20 relationship expressed as "the main heat exchange portion 10A>the first auxiliary heat
exchange portion 10B≥the second auxiliary heat exchange portion 10C."
[0028]
Fig. 4 schematically illustrates variations in the temperatures of air and refrigerant
in the heat exchanger 1 according to Embodiment 1 when the heat exchanger 1 serves
25 as a condenser. The solid line shows the temperature of refrigerant, while the dotted
line shows the temperature of air (the same applies in Figs. 5 and 6). In Fig. 2
described above, the arrows illustrated in the heat exchange portion 10 show the flow of
refrigerant in the heat exchange portion 10 when the heat exchanger 1 serves as a
condenser. When the heat exchanger 1 serves as a condenser, refrigerant flows
30 through the refrigerant inlet/outlet pipe 12A into the distribution header 11A. The
15
refrigerant having flowed into the distribution header 11A passes through the flat heat
transfer tubes 14 belonging to the main heat exchange portion 10A of the airflow
downstream side row. The flat heat transfer tubes 14 exchange heat between
refrigerant passing through the inside of the tubes and outside air passing outside the
5 tubes. At this time, while passing through the flat heat transfer tubes 14, the refrigerant
transfers heat to the outside air. Hereinafter, when the heat exchanger 1 serves as a
condenser, refrigerant transfers heat to the outside air while passing through the flat
heat transfer tubes 14, in all the regions in the same manner.
[0029]
10 The refrigerant is turned back in the turn-back header 13, and passes through the
flat heat transfer tubes 14 belonging to the main heat exchange portion 10A of the
airflow upstream side row. The refrigerant, having passed through the flat heat transfer
tubes 14 of the airflow upstream side row and having exchanged heat with air, flows into
the distribution header 11B. The refrigerant having flowed into the distribution header
15 11B passes through the connection pipes 16 and flows into other spaces in the
distribution header 11B. Then, the refrigerant passes through the flat heat transfer
tubes 14 belonging to the first auxiliary heat exchange portion 10B of the airflow
upstream side row, is turned back in the turn-back header 13, passes through the first
auxiliary heat exchange portion 10B of the airflow downstream side row, and then flows
20 into the distribution header 11A.
[0030]
The refrigerant having flowed into the distribution header 11A passes through the
connection pipes 16 and flows into other spaces in the distribution header 11A. Then,
the refrigerant passes through the flat heat transfer tubes 14 belonging to the second
25 auxiliary heat exchange portion 10C of the airflow downstream side row, is turned back
in the turn-back header 13, passes through the second auxiliary heat exchange portion
10C of the airflow upstream side row, and then flows into the distribution header 11B.
The refrigerant, having flowed in the order described and condensed, flows out through
the refrigerant inlet/outlet pipe 12B. Therefore, when the heat exchanger 1 in
30 Embodiment 1 serves as a condenser, refrigerant that flows in the main heat exchange
16
portions 10A forms a counter flow to the flow of air. The counter flow refers to a flow in
which refrigerant on the downstream side of the refrigerant flow and air on the upstream
side of the air flow exchange heat between them, and also refrigerant on the upstream
side of the refrigerant flow and air on the downstream side of the air flow exchange heat
5 between them.
[0031]
As illustrated in Fig. 4, in the flat heat transfer tubes 14 of the airflow downstream
side row relative to the air flow, heat is exchanged between refrigerant, not having yet
exchanged heat with air, and air having already exchanged heat with refrigerant in the
10 flat heat transfer tubes 14 of the airflow upstream side row. In contrast, in the flat heat
transfer tubes 14 of the airflow upstream side row relative to the air flow, heat is
exchanged between refrigerant, having already exchanged heat with air in the flat heat
transfer tubes 14 of the airflow downstream side row, and air not having yet exchanged
heat with refrigerant. Therefore, in both the flat heat transfer tubes 14 of the airflow
15 upstream side row, and the flat heat transfer tubes 14 of the airflow downstream side
row, a sufficient temperature difference between refrigerant and air can be maintained
to effectively exchange heat between them.
[0032]
Fig. 5 schematically illustrates variations in the temperatures of air and refrigerant
20 in the heat exchanger 1 according to Embodiment 1 when the heat exchanger 1 serves
as an evaporator. When the heat exchanger 1 serves as an evaporator, refrigerant
flows through the refrigerant inlet/outlet pipe 12B into the distribution header 11B. The
refrigerant having flowed into the distribution header 11B passes through the flat heat
transfer tubes 14 belonging to the second auxiliary heat exchange portion 10C of the
25 airflow upstream side row. The flat heat transfer tubes 14 exchange heat between
refrigerant passing through the inside of the tubes and outside air passing outside the
tubes. At this time, while passing through the flat heat transfer tubes 14, the refrigerant
receives heat from the outside air. Hereinafter, when the heat exchanger 1 serves as
an evaporator, refrigerant receives heat from the outside air while passing through the
30 flat heat transfer tubes 14, in all the regions in the same manner.
17
[0033]
The refrigerant is turned back in the turn-back header 13, and passes through the
flat heat transfer tubes 14 belonging to the second auxiliary heat exchange portion 10C
of the airflow downstream side row. The refrigerant, having passed through the flat
5 heat transfer tubes 14 of the airflow downstream side row and having exchanged heat
with air, flows into the distribution header 11A. The refrigerant having flowed into the
distribution header 11A passes through the connection pipes 16 and flows into other
spaces in the distribution header 11A. Then, the refrigerant passes through the flat
heat transfer tubes 14 belonging to the first auxiliary heat exchange portion 10B of the
10 airflow downstream side row, is turned back in the turn-back header 13, passes through
the first auxiliary heat exchange portion 10B of the airflow upstream side row, and then
flows into the distribution header 11B.
[0034]
The refrigerant having flowed into the distribution header 11B passes through the
15 connection pipes 16 and flows into other spaces in the distribution header 11B. Then,
the refrigerant passes through the flat heat transfer tubes 14 belonging to the main heat
exchange portion 10A of the airflow upstream side row, is turned back in the turn-back
header 13, passes through the main heat exchange portion 10A of the airflow
downstream side row, and then flows into the distribution header 11A. The refrigerant,
20 having flowed in the order described and condensed, flows out through the refrigerant
inlet/outlet pipe 12A. Therefore, when the heat exchanger 1 in Embodiment 1 serves
as an evaporator, refrigerant that flows in the main heat exchange portions 10A forms a
parallel flow to the flow of air. The parallel flow refers to a flow in which refrigerant on
the upstream side of the refrigerant flow and air on the upstream side of the air flow
25 exchange heat between them, and also refrigerant on the downstream side of the
refrigerant flow and air on the downstream side of the air flow exchange heat between
them.
[0035]
When the heat exchanger 1 serves as an evaporator, there is a relationship of
30 parallel flow between the air flow and the refrigerant flow in the main heat exchange
18
portions 10A. However, refrigerant initially passes through the second auxiliary heat
exchange portion 10C having a fewer number of the flat heat transfer tubes 14 and a
smaller flow passage area than those of the main heat exchange portion 10A, and
eventually the refrigerant flows into the main heat exchange portion 10A. This causes
5 pressure loss of refrigerant and other problems, and results in a decrease in the
temperature of the refrigerant at the time when the refrigerant passes through the main
heat exchange portion 10A. Therefore, the refrigerant passing through the main heat
exchange portion 10A has a sufficient temperature difference from the air passing
through the heat exchanger 1 to effectively exchange heat between them. This
10 prevents the heat exchanger 1 from degrading its heat exchange performance when the
heat exchanger 1 serves as an evaporator. Thus, the heat exchanger 1 can maintain
its evaporator performance.
[0036]
As described above, in the heat exchanger 1 to be used as the outdoor heat
15 exchanger 230 of the air-conditioning device in Embodiment 1, when the heat
exchanger 1 serves as a condenser, refrigerant flows in such a manner that a flow of
refrigerant in the main heat exchange portion 10A, and a flow of air passing through the
heat exchanger 1 form a counter flow. Due to this configuration, the heat exchanger 1
can maintain a sufficient temperature difference between refrigerant and air to
20 effectively exchange heat between them throughout the entire refrigerant flow passage,
and can consequently improve the heat transfer performance of the heat exchanger 1.
[0037]
In contrast, when the heat exchanger 1 serves as an evaporator, a flow of
refrigerant in the main heat exchange portion 10A, and a flow of air passing through the
25 heat exchanger 1 form a parallel flow. However, this causes pressure loss of
refrigerant in the second auxiliary heat exchange portion 10C, and refrigerant whose
temperature has decreased flows into the main heat exchange portion 10A. Due to
this configuration, the refrigerant passing through the main heat exchange portion 10A
has a sufficient temperature difference from the air passing through the heat exchanger
19
1 to effectively exchange heat between them. Thus, the heat exchanger 1 can
maintain its evaporator performance.
[0038]
In the heat exchanger 1 in Embodiment 1, the number of the flat heat transfer
5 tubes 14 is equal in both two rows, and consequently air can pass through the flat heat
transfer tubes 14 that are equally spaced from each other. In the turn-back header 13,
refrigerant flows are not merged, or the refrigerant is not divided into flows, and one row
of the flat heat transfer tubes 14 are brought into one-to-one correspondence with
another row of the flat heat transfer tubes 14. This can prevent an uneven flow of
10 refrigerant in the turn-back header 13.
[0039]
Embodiment 2
Fig. 6 schematically illustrates variations in the temperatures of air and refrigerant
in the heat exchanger 1 according to Embodiment 2 when the heat exchanger 1 serves
15 as an evaporator. The air-conditioning device and the heat exchanger 1 in
Embodiment 2 have identical configurations to the air-conditioning device and the heat
exchanger 1 described in Embodiment 1. However, the number of the flat heat transfer
tubes 14 grouped into each region of the heat exchanger 1 in Embodiment 2 particularly
has a relationship expressed as "the main heat exchange portion 10A>the first auxiliary
20 heat exchange portion 10B>the second auxiliary heat exchange portion 10C."
[0040]
When the heat exchanger 1 serves as an evaporator, refrigerant flows through
the refrigerant inlet/outlet pipe 12B into the distribution header 11B, and then passes
through the flat heat transfer tubes 14 belonging to the second auxiliary heat exchange
25 portion 10C of the airflow upstream side row, that is the region at the lowermost position
of the heat exchanger 1. At this time, as illustrated in Fig. 6, the air-conditioning device
allows refrigerant to circulate in the refrigerant circuit such that the refrigerant flows into
the second auxiliary heat exchange portion 10C of the airflow upstream side row with a
temperature of the refrigerant higher than the temperature of air that passes through the
30 heat exchange portion 10 of the airflow upstream side row. In the heat exchanger 1
20
included in the air-conditioning device in Embodiment 2, the refrigerant passing through
the second auxiliary heat exchange portion 10C of the airflow upstream side row at the
lowermost position has a temperature higher than the temperature of air. This
prevents drain water accumulating at the bottom of the heat exchanger 1 to be used as
5 the outdoor heat exchanger 230 in the outdoor unit 200 from freezing. With this
configuration, the passage of air through the heat exchanger 1 is prevented from being
interfered with by root ice or the like, and the heat exchange efficiency can be
maintained.
[0041]
10 Embodiment 3
Fig. 7 is an explanatory view illustrating allocation of flat heat transfer tubes 14 in
the heat exchanger 1 according to Embodiment 3. In the heat exchanger 1 in
Embodiment 3, the flat heat transfer tubes 14 belonging to the main heat exchange
portion 10A are further divided into a plurality of subgroups with different distribution
15 paths by baffles in the distribution headers 11 and the turn-back header 13. The
number of the flat heat transfer tubes 14 may not be equal in each of the subgroups, but
may differ between the subgroups.
[0042]
For example, there is a case where an air-sending device includes a side flow fan
20 with its rotational shaft extending in the same direction as the direction in which air
passes through the heat exchanger 1. In that case, the subgroups are arranged at
least in such a manner that the number of the flat heat transfer tubes 14 in the nearest
subgroup from the rotation center of the air-sending device is fewer than those in the
other subgroups. Basically, air flows at a relatively high speed at the rotation center of
25 the air-sending device. In view of this, a fewer number of the flat heat transfer tubes
14 are allocated near the rotation center, while a larger amount of refrigerant flows in
the flat heat transfer tubes 14 with a higher thermal load, so that the heat exchanger 1
can improve its heat exchange performance.
[0043]
30 Embodiment 4
21
Fig. 8 schematically illustrates the configuration of the heat exchanger 1
according to Embodiment 4. In Fig. 8, the same components as those described in
Embodiment 1 are denoted by the same reference numerals as those illustrated in Fig.
2. In the heat exchanger 1 in Embodiment 4, the subgroups of the flat heat transfer
5 tubes 14 belonging to the main heat exchange portion 10A of the airflow upstream side
row are connected to each other by using a layered distributor 17, instead of using the
distribution header 11B. When the heat exchanger 1 serves as an evaporator, the
layered distributor 17 distributes refrigerant flowing therein after the refrigerant has
passed through the first auxiliary heat exchange portion 10B of the airflow upstream
10 side row, the distribution header 11B, and the connection pipes 16. When the heat
exchanger 1 serves as an evaporator, the layered distributor 17 merges refrigerant
flows having passed through the main heat exchange portion 10A.
[0044]
Fig. 9 illustrates an example of the configuration of the layered distributor 17
15 according to Embodiment 4. The layered distributor 17 is manufactured by stacking a
plurality of plates 17A on one another, that are a plurality of plate-like parts including
through holes or through grooves serving as a flow passage. The plates 17A include
flow passage grooves 17B and flow passage holes 17C. The flow passage grooves
17B allow refrigerant to pass therethrough. The flow passage holes 17C are through
20 holes communicating with the adjacent plates 17A to allow the refrigerant to pass
therethrough. The layered distributor 17 is not limited to having the configuration
illustrated in Fig. 9.
[0045]
The large region of main heat exchange portion 10A uses the layered distributor
25 17 to distribute refrigerant, and can thereby minimize uneven refrigerant distribution, such
as gas-phase refrigerant of the two-phase gas-liquid refrigerant passing excessively
through the flat heat transfer tubes 14 arranged on the upper side. This can improve the
efficiency in heat exchange.
Industrial Applicability
30 [0046]
22
In Embodiment 1 described above, the heat exchangers 1 are used as the
outdoor heat exchanger 230 of the outdoor unit 200, however, use of the heat
exchangers 1 is not limited to this example. The heat exchangers 1 may be used as
the indoor heat exchanger 110 of the indoor unit 100, or may be used as both the
5 outdoor heat exchanger 230 and the indoor heat exchanger 110.
[0047]
In Embodiment 1 described above, the air-conditioning device has been
explained. However, the heat exchanger 1 is also applicable to other refrigeration
cycle devices, such as a refrigerator, a freezer, or a water heater.
10 [0048]
In Embodiments 1 to 4 described above, the heat exchanger 1 is described as a
corrugated-fin and tube heat exchanger including the heat exchange portion 10 using
the flat heat transfer tubes 14. However, the heat exchanger 1 may include the heat
exchange portion 10 configured to exchange heat by using, for example, circular heat
15 transfer tubes.
Reference Signs List
[0049]
1: heat exchanger, 10: heat exchange portion, 10A: main heat exchange portion,
10B: first auxiliary heat exchange portion, 10C: second auxiliary heat exchange portion,
20 11, 11A, 11B: distribution header, 12, 12A, 12B: refrigerant inlet/outlet pipe, 13: turnback header, 14: flat heat transfer tube, 15: corrugated fin, 16: connection pipe, 17:
layered distributor, 17A: plate, 17B: flow passage groove, 17C: flow passage hole, 100:
indoor unit, 110: indoor heat exchanger, 120: expansion valve, 130: indoor air-sending
device, 200: outdoor unit, 210: compressor, 220: four-way valve, 230: outdoor heat
25 exchanger, 240: accumulator, 250: outdoor air-sending device, 300: refrigerant pipe

We Claim :
[Claim 1]
A heat exchanger comprising:
a heat exchange portion in which a plurality of heat transfer tubes, in which
5 refrigerant flows, are arranged in a height direction, the plurality of heat transfer tubes
being configured to exchange heat between the refrigerant and air;
a turn-back portion to which one end of each of the plurality of heat transfer tube
is connected and which is configured to allow the refrigerant to flow between two rows
of heat exchange portions arranged in an airflow direction,
10 one of the two rows of heat exchange portions being the heat exchange portion
and arranged on an airflow upstream side,
an other of the two rows of heat exchange portions being the heat exchange
portion and arranged on an airflow downstream side; and
a plurality of distribution merge portions to each of which the other end of the heat
15 transfer tube of the heat exchange portion of each row is connected, and which is
configured to distribute the refrigerant to the heat transfer tube or merge refrigerant
flows from the heat exchange portions,
the plurality of heat transfer tubes of the heat exchange portion being grouped
into, in order from an upper side in the height direction,
20 a main heat exchange portion,
a first auxiliary heat exchange portion having fewer number of the heat
transfer tubes than those of the main heat exchange portion, and
a second auxiliary heat exchange portion having fewer number of the heat
transfer tubes than those of the first auxiliary heat exchange portion,
25 and being configured to, when the heat exchanger serves as a condenser, allow
the refrigerant to flow through the heat exchanger in order of
the main heat exchange portion of the airflow downstream side row,
the main heat exchange portion of the airflow upstream side row,
24
the first auxiliary heat exchange portion of the airflow upstream side row,
the first auxiliary heat exchange portion of the airflow downstream side
row,
the second auxiliary heat exchange portion of the airflow downstream side
5 row, and
the second auxiliary heat exchange portion of the airflow upstream side
row, and
and allow the refrigerant to flow out of the heat exchanger.
[Claim 2]
10 The heat exchanger of claim 1, wherein the heat exchange portion of the airflow
upstream side row, and the heat exchange portion of the airflow downstream side row
have equal number of the heat transfer tubes.
[Claim 3]
The heat exchanger of claim 1 or 2, wherein in the main heat exchange portion,
15 the heat transfer tubes are further divided into a plurality of subgroups by distribution
paths of the refrigerant from the distribution merge portions.
[Claim 4]
The heat exchanger of claim 3, wherein the main heat exchange portion has
fewer number of the heat transfer tubes in the subgroups through which a large amount
20 of the air passes than those in other subgroups.
[Claim 5]
The heat exchanger of any one of claims 1 to 4, wherein the turn-back portion
connects the heat transfer tubes of the main heat exchange portion in the heat
exchange portion of the airflow upstream side row, and the heat transfer tubes of the
25 main heat exchange portion in the heat exchange portion of the airflow downstream
side row to each other on a one-to-one basis.
[Claim 6]
The heat exchanger of any one of claims 1 to 5, wherein the distribution merge
portions include a layered distributor of a plurality of plate-like parts stacked on one
30 another.
25
[Claim 7]
The heat exchanger of any one of claims 1 to 6, wherein each of the heat transfer
tubes is a flat heat transfer tube having a flat shape in cross-section, and having flow
passages therein through which the refrigerant flows.
5 [Claim 8]
A refrigeration cycle device comprising the heat exchanger of any one of claims 1
to 7 to serve at least as a condenser.
[Claim 9]
The refrigeration cycle device of claim 8, wherein
10 the heat transfer tubes of the heat exchange portion in the heat exchanger have a
relationship expressed as
number of the heat transfer tubes of the main heat exchange
portion>number of the heat transfer tubes of the first auxiliary heat exchange
portion>number of the heat transfer tubes of the second auxiliary heat exchange
15 portion, and
when the heat exchanger serves as an evaporator, a temperature of refrigerant
flowing into the heat exchanger from the second auxiliary heat exchange portion of the
airflow upstream side row is higher than a temperature of the air flowing into the heat
exchange portion.
20 [Claim 10]
The refrigeration cycle device of claim 8 or 9, comprising an air-sending device
including a fan and oriented with a rotational shaft of the fan extending in a same
direction as a direction in which air passes through the heat exchange portion, the airsending device being configured to allow the air to pass through the heat exchange
25 portion, wherein

26
number of the heat transfer tubes in the subgroup nearest in distance from a
rotation center of the fan is fewer than those in the other subgroups.