FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
HEAT EXCHANGER AND AIR-CONDITIONING APPARATUS
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
Technical Field
[0001]
5 The present disclosure relates to a heat exchanger including a first heat
exchange unit and a second heat exchange unit, and an air-conditioning apparatus
including the heat exchanger.
Background Art
[0002]
10 An air-conditioning apparatus includes a heat exchanger that is a component of
a refrigeration cycle circuit and that operates as a condenser. The condenser
causes heat exchange to be performed between outside air and gas refrigerant that
has flowed into the condenser. The refrigerant subjected to heat exchange to be in a
two-phase gas-liquid state changes into liquid refrigerant, and the liquid refrigerant
15 flows out from the condenser. As such a condenser, heat transfer tube groups are
provided on the windward side and the leeward side, one end of each of the heat
transfer tube groups is folded, and refrigerant that has been in a two-phase gas-liquid
state on the leeward side is caused to flow toward the windward side, thereby
improving the heat exchanger performance. As an existing method of turning back
20 refrigerant, there is provided a method in which refrigerant streams are made to join
together in a header at outlets of the heat transfer tubes on the leeward side, thereby
obtaining single refrigerant, and the refrigerant is supplied to a header at inlets of the
heat transfer tubes on the windward side (see, for example, Patent Literature 1).
Citation List
25 Patent Literature
[0003]
Patent Literature 1: Japanese Unexamined Patent Application Publication No.
2019-132537
Summary of Invention
30 Technical Problem
3
[0004]
In an existing refrigerant circuit, in an air velocity distribution in a state in which
a heat exchanger that serves as a condenser is mounted in a top blowing housing, a
large amount of liquid phase refrigerant is generated in heat transfer tubes on the
5 upper side. However, when outlets of heat transfer tubes communicate with each
other in a header, liquid refrigerant that has dripped from the heat transfer tubes on
the upper side in the header cannot be elevated by only refrigerant in a heat transfer
tube on the lowermost side in the direction of gravity and is accumulated, thus
lowering the performance, in particular, at an intermediate load.
10 [0005]
The present disclosure is made in view of the above circumstances, and
relates to a heat exchanger and an air-conditioning apparatus that are capable of
improving the heat exchange performance and that include a first heat exchange unit
and a second heat exchange unit.
15 Solution to Problem
[0006]
A heat exchanger according to an embodiment of the present disclosure
includes a first heat exchange unit and a second heat exchange unit. The first heat
exchange unit includes: a first intermediate header extending in a direction of gravity;
20 a first heat transfer tube connected to the first intermediate header, and used in heat
exchange between refrigerant and air; and a first partition that partitions an interior of
the first intermediate header into a first space and a second space located below the
first space.
The second heat exchange unit includes: a second intermediate header provided
25 alongside of the first heat exchange unit and on a windward side relative to the first
heat exchange unit, the second intermediate header extending in the direction of
gravity; a second heat transfer tube connected to the second intermediate header and
used in heat exchange between the refrigerant and the air; and a second partition that
partitions an interior of the second intermediate header into a third space and a fourth
30 space located below the third space. A plurality of first heat transfer tubes including
4
the first heat transfer tube are provided, and include a first heat transfer tube that
extends to communicate with the first space, and a first heat transfer tube that
extends to communicate with the second space. The first intermediate header
defines the first space and has a first outlet through which the refrigerant flows out.
5 The first intermediate header defines the second space and has a second outlet
through which the refrigerant flows out. The second intermediate header is
connected to the first intermediate header and has a first inlet through which the
refrigerant flows from the first outlet into the third space, and a second inlet through
which the refrigerant flows from the second outlet into the third space.
10 Advantageous Effects of Invention
[0007]
According to the embodiment of the present disclosure, the second
intermediate header is connected to the first intermediate header and has the first
inlet through which liquid-dominated refrigerant flows from the first outlet into the third
15 space, and the second inlet through which gas-dominated refrigerant flows from the
second outlet into the third space. Thus, it is possible to mix the liquid-dominated
refrigerant and the gas-dominated refrigerant in the third space and to reduce
occurrence of dripping of liquid refrigerant from dripping onto the bottom of the
second intermediate header. As a result, it is possible to improve the heat exchange
20 performance in a cooling operation.
Brief Description of Drawings
[0008]
[Fig. 1] Fig. 1 is a configuration diagram of an air-conditioning apparatus
according to Embodiment 1.
25 [Fig. 2] Fig. 2 is a perspective view of an outdoor heat exchanger according to
Embodiment 1.
[Fig. 3] Fig. 3 is a vertical sectional view illustrating the vicinity of a first
intermediate header and a second intermediate header of the outdoor heat exchanger
according to Embodiment 1.
5
[Fig. 4] Fig. 4 is a vertical sectional view illustrating the flow of refrigerant in the
vicinity of a first intermediate header and a second intermediate header of an existing
outdoor heat exchanger.
[Fig. 5] Fig. 5 is a vertical sectional view illustrating the flow of refrigerant in the
5 vicinity of the first intermediate header and the second intermediate header of the
outdoor heat exchanger according to Embodiment 1.
[Fig. 6] Fig. 6 is a conceptual schematic diagram illustrating an air velocity
distribution and the flow rate of refrigerant that flows into the first intermediate header
of the existing outdoor heat exchanger.
10 [Fig. 7] Fig. 7 is a conceptual schematic diagram illustrating an air velocity
distribution and the flow rate of refrigerant that flows into the first intermediate header
of the outdoor heat exchanger according to Embodiment 1.
[Fig. 8] Fig. 8 illustrates a performance curve for the operating load of the
outdoor heat exchanger according to Embodiment 1.
15 [Fig. 9] Fig. 9 is a schematic diagram illustrating an example of a refrigerant
passage configuration of the outdoor heat exchanger according to Embodiment 1.
[Fig. 10] Fig. 10 is a vertical sectional view illustrating a first intermediate
header and a second intermediate header of an outdoor heat exchanger according to
Embodiment 2.
20 [Fig. 11] Fig. 11 is a vertical sectional view illustrating a first intermediate
header and a second intermediate header of an outdoor heat exchanger according to
Embodiment 3.
[Fig. 12] Fig. 12 is a top sectional view of a first intermediate header and a
second intermediate header according to Embodiment 4.
25 [Fig. 13] Fig. 13 is an enlarged sectional view taken along line A-A in Fig. 12.
[Fig. 14] Fig. 14 is an enlarged sectional view taken along line A-A in Fig. 12
and illustrating a first modification of the first intermediate header and the second
intermediate header according to Embodiment 4.
6
[Fig. 15] Fig. 15 is an enlarged sectional view taken along line A-A in Fig. 12
and illustrating a second modification of the first intermediate header and the second
intermediate header according to Embodiment 4.
Description of Embodiments
5 [0009]
Examples of a heat exchanger and an air-conditioning apparatus according to
each of the embodiments in the present disclosure will be described with reference to
the drawings, etc. In each of figures in the drawings that will be referred to below,
components that are the same as or equivalent to those in a previous figure or
10 previous figures are denoted by the same reference signs. The configurations of the
components that will be described below regarding the embodiments are merely
examples. The following descriptions concerning configurations of the heat
exchanger and the air-conditioning apparatus according to each of the embodiments
in the present disclosure are not limiting. Combinations of such configurations are
15 not limited to only combinations of configurations in the same embodiment; that is,
configurations described regarding different embodiments may be combined. In the
figures, relationships in size between components may differ from those of actual
components which are obtained by putting each of the embodiments in the present
disclosure into practice.
20 [0010]
Embodiment 1
Configuration
Fig. 1 is a configuration diagram of an air-conditioning apparatus 200 according
to Embodiment 1. An outlined arrow and a black arrow indicated along refrigerant
25 pipes 18 in Fig. 1 each indicate the flow direction of the refrigerant in a cooling
operation. The outlined arrow indicates the flow direction of gas refrigerant, and the
black arrow indicates the flow direction of liquid refrigerant. In addition, hatched
arrows indicated close to a first intermediate header 1 and a second intermediate
header 2 schematically indicate two-phase gas-liquid refrigerant. Fig. 1 illustrates
30 the flow of the refrigerant in the case where an outdoor heat exchanger 10 operates
7
as a condenser. In Fig. 1, a direction AF indicates the flow direction of air, and an
arrow 90 indicates the direction of gravity.
[0011]
The air-conditioning apparatus 200 includes a compressor 14 which
5 compresses refrigerant, the outdoor heat exchanger 10 which operates as a
condenser, an expansion device 17 which decompresses and expands the
refrigerant, and an indoor heat exchanger 16 which operates as an evaporator. The
compressor 14, the outdoor heat exchanger 10, the expansion device 17, and the
indoor heat exchanger 16 are sequentially connected by refrigerant pipes 18,
10 whereby a refrigeration cycle circuit is formed.
[0012]
The compressor 14 and the outdoor heat exchanger 10 are housed in an
outdoor unit 201. A housing of the outdoor unit 201 is a top blowing housing which is
provided with a fan 13 configured to supply outdoor air to the outdoor heat exchanger
15 10 and send air upward. The indoor heat exchanger 16 and the expansion device
17 are housed in an indoor unit 202. The indoor unit 202 also houses an indoor fan
(not illustrated) configured to supply indoor air that is air in an air-conditioning target
space to the indoor heat exchanger 16.
[0013]
20 The outdoor heat exchanger 10 includes a first heat exchange unit 11 and a
second heat exchange unit 12. The first heat exchange unit 11 includes the first
intermediate header 1 and first heat transfer tubes 3_1 (see Fig. 3). The first header
extends in the direction of gravity 90. The first heat transfer tubes 3_1 are
connected to the first intermediate header 1. Also, at the first heat transfer tubes
25 3_1, heat exchange is performed between the refrigerant and air. The second heat
exchange unit 12 includes the second intermediate header 2 and second heat
transfer tubes 3_2. The second intermediate header 2 is provided alongside of the
first heat exchange unit 11 and on the windward side relative to the first heat
exchange unit 11 and extends in the direction of gravity 90. The second heat
30 transfer tubes 3_2 are connected to the second intermediate header 2. Also, at the
8
second heat transfer tubes 3_2, heat exchange is performed between the refrigerant
and air.
[0014]
Next, a configuration of the outdoor heat exchanger 10 will be described in
5 detail.
[0015]
Fig. 2 is a perspective view of the outdoor heat exchanger 10 according to
Embodiment 1. Fig. 3 is a vertical sectional view illustrating the vicinity of the first
intermediate header 1 and the second intermediate header 2 and the vicinity of the
10 first intermediate header 1 and the second intermediate header 2 in the outdoor heat
exchanger 10 according to Embodiment 1. Fig. 3 is a vertical sectional view parallel
to the direction in which the first heat transfer tubes 3_1 and the second heat transfer
tubes 3_2 extend.
[0016]
15 As illustrated in Fig. 2, the outdoor heat exchanger 10 is mounted in a top
blowing housing 203 of the outdoor unit 201 provided with the fan 13 configured to
send air upward. In upper part of the top blowing housing 203, an air outlet is
provided to allow air sent out from the fan 13 to flow out. As illustrated in Fig. 3, the
outdoor heat exchanger 10 includes the first heat exchange unit 11 and the second
20 heat exchange unit 12, which is provided upstream from the first heat exchange unit
11 in the flow direction AF of air. The outdoor heat exchanger 10 includes at least
two rows of the first heat exchange unit 11 and the second heat exchange unit 12.
[0017]
The first heat exchange unit 11 includes a plurality of first heat transfer tubes
25 3_1. The first heat transfer tubes 3_1 extend in a horizontal direction and are
disposed at regular intervals in an up-down direction that are determined in advance.
The second heat exchange unit 12 includes a plurality of second heat transfer tubes
3_2. The second heat exchange unit 12 extends in the horizontal direction and is
disposed at regular intervals in the up-down direction that are determined in advance.
30 [0018]
9
When the outdoor heat exchanger 10 operates as a condenser, refrigerant that
flows in the first heat transfer tubes 3_1 and the second heat transfer tubes 3_2 is
cooled by outdoor air to condense. In Embodiment 1, as illustrated in Fig. 3, to
promote heat exchange between the refrigerant and outdoor air, a plurality of fins 4
5 are connected to the first heat transfer tubes 3_1, and a plurality of fins (not
illustrated) are connected to the second heat transfer tubes 3_2.
[0019]
The first heat exchange unit 11 provided downstream of airflow and the second
heat exchange unit 12 provided upstream of airflow are successively connected by
10 the first intermediate header 1 and the second intermediate header 2. The first
intermediate header 1 is configured such that the first heat transfer tubes 3_1 are
inserted in a pipe having a certain volume. The second intermediate header 2 is
formed such that the second heat transfer tubes 3_2 are inserted in a pipe having a
certain volume. The first intermediate header 1 is a header that connects at least
15 two of the first heat transfer tubes 3_1 arranged in the same row, in the same space.
The second intermediate header 2 is a header that connects at least two of the
second heat transfer tubes 3_2 arranged in the same row, in the same space.
[0020]
The first intermediate header 1 is partitioned by a first partition 35 into a first
20 space 21 located on its upper side and a second space 22 located on its lower side.
At least one of the first heat transfer tubes 3_1 connected to the first intermediate
header 1 extends to communicate with the first space 21. At least two of the first
heat transfer tubes 3_1 connected to the first intermediate header 1 extend to
communicate with the second space 22.
25 [0021]
A pipe wall of the first intermediate header 1 that defines the first space 21 has
a first outlet 31_1 through which refrigerant flows out. A pipe wall of the first
intermediate header 1 that defines the second space 22 has a second outlet 32_1
through which refrigerant flows out.
30
10
[0022]
The second intermediate header 2 is partitioned by a second partition 36 into a
third space 23 located on its upper side and a fourth space 24 located on its lower
side. At least one of the second heat transfer tubes 3_2 extends to communicate
5 with the third space 23. A pipe wall of the second intermediate header 2 that defines
the third space 23 has a first inlet 33_1 and a second inlet 34_1 through which
refrigerant flows in.
[0023]
A first connection pipe 31 is extended from the first outlet 31_1 to the first inlet
10 33_1 and thus causes the first space 21 to communicate with the third space 23. A
second connection pipe 32 is extended from the second outlet 32_1 to the second
inlet 34_1 and thus causes the second space 22 to communicate with the third space
23. The second outlet 32_1 is located at a higher level than the second partition 36.
[0024]
15 The first outlet 31_1 and the first inlet 33_1 may be provided to directly
communicate with each other without the first connection pipe 31. In addition, the
second outlet 32_1 and the second inlet 34_1 may be provided to directly
communicate with each other without the second connection pipe 32.
[0025]
20 In addition, the sum of the number of the first heat transfer tubes 3_1 which
communicates with the first space 21 and the number of the first heat transfer tubes
3_1 which communicate with the second space is larger than the number of the
second heat transfer tubes 3_2.
[0026]
25 Operations
Next, the operations of the air-conditioning apparatus 200 will be described.
Heating Operation
First of all, a heating operation of the air-conditioning apparatus 200 will be
described. High-temperature and high-pressure gas refrigerant obtained through
11
compression by the compressor 14 passes through a four-way valve (not illustrated)
and flows into the indoor heat exchanger 16 which operates as a condenser.
[0027]
The high-temperature and high-pressure gas refrigerant that has flowed into
5 the indoor heat exchanger 16 is cooled to change into low-temperature liquid
refrigerant while transferring heat to indoor air, and the low-temperature liquid
refrigerant flows out from the indoor heat exchanger 16. The liquid refrigerant that
has flowed out from the indoor heat exchanger 16 is decompressed at the expansion
device 17 to change into low-temperature and low-pressure two-phase gas-liquid
10 refrigerant, and the low-temperature and low-pressure two-phase gas-liquid
refrigerant flows into a distributor (not illustrated) of the outdoor heat exchanger 10
which operates as an evaporator.
[0028]
The low-temperature and low-pressure two-phase gas-liquid refrigerant that
15 has flowed into the distributor of the outdoor heat exchanger 10 is distributed to the
second heat transfer tubes 3_2. Then, the refrigerant which flows through the
second heat transfer tubes 3_2 is heated and evaporated by outdoor air, and flow into
the first heat transfer tubes 3_1 via the first connection pipe 31 and the second
connection pipe 32. The refrigerant that has flowed into the first heat transfer tubes
20 3_1 is heated and evaporated by outdoor air to change into low-pressure gas
refrigerant, and the low-pressure gas refrigerant flows out from the first heat transfer
tubes 3_1. The low-pressure gas refrigerant that has flowed out from the first heat
transfer tubes 3_1 joins each other in a joining pipe (not illustrated) to flow as single
refrigerant. Thereafter, the refrigerant flows out from the outdoor heat exchanger 10.
25 The low-pressure gas refrigerant that has flowed out from the outdoor heat exchanger
10 passes through a four-way valve (not illustrated) and is thereafter sucked into the
compressor 14. The low-pressure gas refrigerant sucked into the compressor 14 is
re-compressed by the compressor 14 to change into high-temperature and highpressure gas refrigerant.
30
12
[0029]
Cooling Operation
Next, the cooling operation of the air-conditioning apparatus 200 will be
described.
5 High-temperature and high-pressure gas refrigerant obtained by compression
by the compressor 14 passes through the four-way valve (not illustrated) and flows
into the joining pipe (not illustrated) of the outdoor heat exchanger 10 which operates
as a condenser.
[0030]
10 The High-temperature and high-pressure gas refrigerant that has flowed into
the joining pipe of the outdoor heat exchanger 10 is distributed to the first heat
transfer tubes 3_1 of the outdoor heat exchanger 10. Then, the refrigerant that flows
through the first heat transfer tubes 3_1 is cooled by outdoor air to condense and thus
change into low-temperature liquid refrigerant. The low-temperature liquid
15 refrigerant flows in the second heat transfer tubes 3_2 via the first connection pipe 31
and the second connection pipe 32 and flows out from the second heat transfer tubes
3_2.
[0031]
The low-temperature liquid refrigerant that has flowed out from the second heat
20 transfer tubes 3_2 join together in the distributor (not illustrated) to combine into
single refrigerant. Then, the refrigerant flows out from the outdoor heat exchanger
10. The liquid refrigerant that has flowed out from the outdoor heat exchanger 10 is
decompressed to change into low-temperature and low-pressure two-phase gasliquid refrigerant at the expansion device 17, and the low-temperature and low25 pressure two-phase gas-liquid refrigerant flows into the indoor heat exchanger 16
which operates as an evaporator. The low-temperature and low-pressure two-phase
gas-liquid refrigerant that has flowed into the indoor heat exchanger 16 is evaporated
while receiving heat from indoor air, to change into low-pressure gas refrigerant, and
the low-pressure gas refrigerant flows out from the indoor heat exchanger 16. The
30 low-pressure gas refrigerant that has flowed out from the indoor heat exchanger 16
13
passes through the four-way valve (not illustrated) and is then sucked into the
compressor 14. The low-pressure gas refrigerant sucked into the compressor 14 is
re-compressed to change into high-temperature and high-pressure gas refrigerant in
the compressor 14.
5 [0032]
In the air-conditioning apparatus 200 having the above configuration, when the
outdoor heat exchanger 10 operates as a condenser, at the first heat exchange unit
11, gas refrigerant exchanges heat with downstream airflow and changes into twophase gas-liquid refrigerant. The two-phase gas-liquid refrigerant flows from the first
10 heat transfer tubes 3_1 of the first heat exchange unit 11 into the first space 21 and
the second space 22 of the first intermediate header 1. The two-phase gas-liquid
refrigerant is mixed together in each of the first space 21 and the second space 22.
Thereafter, the mixed refrigerant flows from the first space 21 and the second space
22 into the third space 23 of the second intermediate header 2 of the second heat
15 exchange unit 12 through the first connection pipe 31 and the second connection pipe
32. In the third space 23, the two-phase gas-liquid refrigerant that has flowed
therein through the first connection pipe 31 and the second connection pipe 32 is
mixed together. The mixed refrigerant is split into refrigerant streams to flow into the
heat transfer tubes 3 of the second heat exchange unit 12, and the refrigerant
20 streams exchange heat with upstream airflow.
[0033]

Next, advantages of the first intermediate header 1 and the second
intermediate header 2 of the outdoor heat exchanger 10 according to Embodiment 1
25 will be described. First of all, an existing outdoor heat exchanger 10 will be
described with reference to Fig. 4 as an outdoor heat exchanger with which the
outdoor heat exchanger 10 according to Embodiment 1 should be compared.
14
[0034]
Fig. 4 is a vertical sectional view illustrating the flow of refrigerant in the vicinity
of the first intermediate header 1 and the second intermediate header 2 of the existing
outdoor heat exchanger 10.
5 [0035]
In the existing outdoor heat exchanger 10, the first heat transfer tubes 3_1 of
the first heat exchange unit 11 located on a downstream side in airflow are arranged
at predetermined intervals in the up-down direction and are connected to the first
intermediate header 1. The second heat transfer tubes 3_2 of the second heat
10 exchange unit 12 located on an upstream side in airflow are arranged at
predetermined intervals in the up-down direction and are connected to the second
intermediate header 2. The first intermediate header 1 and the second intermediate
header 2 are connected by the first connection pipe 31.
[0036]
15 Gas refrigerant that has flowed into the first heat exchange unit 11 exchanges
heat with downstream airflow to change into two-phase gas-liquid refrigerant, and the
two-phase gas-liquid refrigerant flows into the first intermediate header 1. In this
case, regarding the velocity of airflow that passes through the first heat exchange unit
11, the velocity of airflow between fins 4 provided on the upper side and between first
20 heat transfer tubes 3_1 provided on the upper side is increased by the fan 13, which
is provided in the top blowing housing configured to send air upward. The velocity of
airflow that passes between fins 4 provided on the lower side and between the first
heat transfer tubes 3_1 provided on the lower side is decreased. From the outlets of
the first heat transfer tubes 3_1 on the upper side, liquid-dominated refrigerant 102
25 which has a higher mass flow ratio of liquid refrigerant than that at the outlets on the
lower side, flows into the first intermediate header 1. From the outlets of the first
heat transfer tubes 3_1 on the lower side, gas-dominated refrigerant 103 which has a
higher mass flow ratio of gas refrigerant than that at the outlets on the upper side
flows into the first intermediate header 1.
30
15
[0037]
In this case, the liquid refrigerant 100 has a higher density than the gas
refrigerant 101 and thus drips down in the first intermediate header 1. In a lower
region of the first space 21, a driving force that causes the refrigerant to flow upward
5 is an inertial force of refrigerant that has flowed out from first heat transfer tubes 3_1
located upstream in the flow of the refrigerant and located below the lower region of
the first space 21. In a lower region of the interior of the first intermediate header 1
in which the flow rate of the refrigerant is low, the inertial force of the refrigerant is
small. Therefore, the dripped liquid refrigerant is not raised upward, thus causing a
10 liquid accumulation 104. In particular, in a low-load operation, the flow rate of the
refrigerant is low, and the inertial force of the refrigerant in the horizontal direction in
the first heat transfer tubes 3_1 is small. Accordingly, liquid refrigerant in the lower
region of the first space 21 enters first heat transfer tubes 3_1 located on the lower
side, thus causing liquid backflow 105.
15 [0038]
Therefore, in the existing outdoor heat exchanger 10, the flow of the refrigerant
is hindered under a condition under which the amount of refrigerant that circulates in
the refrigeration cycle circuit is small as in a low-power operation of the airconditioning apparatus 200, thus causing the refrigerant accumulation and backflow
20 105. As a result, the region of the first heat exchange unit 11 in which heat
exchange is performed is reduced, thus deteriorating the heat exchange performance
of the condenser.
[0039]
Fig. 5 is a vertical sectional view illustrating the flow of refrigerant in the vicinity
25 of the first intermediate header 1 and the second intermediate header of the outdoor
heat exchanger 10 according to Embodiment 1.
[0040]
In the outdoor heat exchanger 10 according to Embodiment 1, the first
intermediate header 1 is partitioned into the first space 21 and the second space 22
30 by the first partition 35. At least one of upper ones of the first heat transfer tubes
16
3_1 connected to the first intermediate header 1 is made to communicate with the first
space 21. At least two of lower ones of the first heat transfer tubes 3_1 are made to
communicate with the second space 22.
[0041]
5 Therefore, the liquid-dominated refrigerant 102 that flows out from the first heat
transfer tubes 3_1 on the upper side does not enter the second space 22 in the first
intermediate header 1. The liquid-dominated refrigerant 102 flows into the third
space 23 of the second intermediate header 2 via the first connection pipe 31. As a
result, the liquid accumulation 104 in the second space 22 is reduced, thereby
10 ensuring a sufficient region in which heat exchange is performed, and thus improving
the heat exchange performance of the condenser.
[0042]
Such an advantage is remarkable particularly in a low-load operation in which
the flow rate of the refrigerant is low. In Embodiment 1, the flow rate of refrigerant
15 that flows in the second connection pipe 32 is the sum of the flow rates of refrigerant
that flows from the first heat transfer tubes 3_1 which communicates with the second
space 22. In addition, it is possible to design the passage diameter of the second
connection pipe 32 regardless of the passage diameter of the first heat transfer tubes
3_1 and to thus reduce the probability that the liquid backflow 105 from the third
20 space 23 into the second space 22 will occur (see Fig. 4).
[0043]
Fig. 6 is a conceptual schematic diagram illustrating an air velocity distribution
and the flow rate of refrigerant that flows into the first intermediate header 1 of the
existing outdoor heat exchanger 10. Fig. 6 indicates, with a white bar graph, the flow
25 rate of refrigerant that flows in each of the first heat transfer tubes 3_1 located at
respective levels and connected to the existing first intermediate header 1, and
illustrates, with a solid line, an air velocity distribution in the height direction of the top
blowing housing.
30
17
[0044]
Fig. 7 is a conceptual schematic diagram illustrating an air velocity distribution
and the flow rate of refrigerant that flows into the first intermediate header 1 of the
outdoor heat exchanger 10 according to Embodiment 1. Fig. 7 indicates, with a
5 black bar graph, the flow rate of refrigerant that flows in each of the first heat transfer
tubes 3_1 located at respective levels and connected to the first intermediate header
1 in Embodiment 1, and indicates, with a solid line, the air velocity distribution in the
height direction of the top blowing housing.
[0045]
10 It should be noted that the two-phase gas-liquid refrigerant has the following
properties: when the amount of gas refrigerant in the two-phase gas-liquid refrigerant
is large, the volume flow rate of the refrigerant is high, thus increasing the pressure
loss of the refrigerant, and when the amount of liquid refrigerant in the two-phase gasliquid refrigerant is large, the volume flow rate of the refrigerant is low, thus reducing
15 the pressure loss of the refrigerant.
[0046]
As illustrated in Fig. 4, in the existing outdoor heat exchanger 10, refrigerant at
the outlets of the first heat transfer tubes 3_1 is mixed at the outlet of the first
intermediate header 1, and the mixed refrigerant flows into the second intermediate
20 header 2 through the first connection pipe 31. Thus, as indicated in Fig. 6, the
differences in the flow rate of the refrigerant between the first heat transfer tubes 3_1
are small. By contrast, in the top blowing housing, the air velocity on the upper side
where the passage length of the airflow is short is high, and the air velocity on the
lower side where the passage length of the airflow is long is low. Thus, the
25 discrepancy between the air velocity distribution and the flow rate distribution of the
refrigerant is increased, thus causing deterioration of the performance.
[0047]
By contrast, in the outdoor heat exchanger 10 according to Embodiment 1, the
first space 21 which is located at the outlets of the first heat transfer tubes 3_1 on the
30 upper side, and the second space 22 which is located at the outlets of the first heat
18
transfer tubes 3_1 on the lower side, are partitioned off so as not to communicate with
each other. Thus, as indicated in Fig. 7, the flow rate of refrigerant that flows in each
of the first heat transfer tubes 3_1 which communicate with the first space 21 into
which the liquid-dominated refrigerant 102 flows is higher than the flow rate of
5 refrigerant that flows in each of the first heat transfer tubes 3_1 connected to the
second space 22 into which the gas-dominated refrigerant 103 flows. Therefore, the
discrepancy between the air velocity distribution and the flow rate distribution of the
refrigerant is reduced, thus improving the heat exchange performance.
[0048]
10 Fig. 8 indicate a performance curve for the operating load of the outdoor heat
exchanger 10 according to Embodiment 1. The horizontal axis represents the ratio
of a cooling capacity to the maximum cooling power, and the vertical axis represents
the ratio of the performance to the theoretical maximum performance of the outdoor
heat exchanger 10 with each operating power. Fig. 8 indicates, with a solid line, a
15 characteristic curve in Embodiment 1, and indicates, with a dashed line, a
characteristic curve in the existing configuration.
[0049]
In the existing configuration, the liquid accumulation 104 (see Fig. 4) occurs in
the first intermediate header 1 particularly in the low-load operation, thus deteriorating
20 the performance. In the configuration according to Embodiment 1, occurrence of the
above liquid accumulation is reduced, thereby improving the performance of the
outdoor heat exchanger 10 particularly in the low-load operation. In addition, the
refrigerant distribution in the first heat transfer tubes 3_1 is made to conform to the air
velocity distribution in the top blowing housing, thereby improving the performance of
25 the outdoor heat exchanger 10 in the low-load to high-load operations, and thus
improving the energy efficiency of the air-conditioning apparatus 200.
[0050]
Even when the housing of the outdoor unit 201 is not the top blowing housing,
since the outdoor heat exchanger 10 is mounted in the outdoor unit 201, the amount
30 of liquid refrigerant that drips to the lower space of the second space 22 of the first
19
intermediate header 1 is reduced, thus improving the performance. In addition, in
the case where the outdoor heat exchanger 10 is mounted in the top blowing housing,
a large amount of liquid refrigerant is generated on the upper side in the direction of
gravity in the cooling operation. Therefore, the amount of liquid refrigerant that drips
5 to the lower space of the second space 22 of the first intermediate header 1 is
reduced, as compared with the existing configuration in the same power operation as
the configuration of Embodiment 1, thus greatly improving the performance.
[0051]
The air-conditioning apparatus 200 described above is an example of the air10 conditioning apparatus 200 according to Embodiment 1. For example, the outdoor
heat exchanger 10 may be mounted in the indoor unit 202 of the air-conditioning
apparatus 200. In addition, the advantage can still be obtained even when the
number of spaces partitioned off in the first intermediate header 1 is three or more,
and the number of spaces partitioned off in the first intermediate header 1 is design
15 matter to be selected in consideration of the improvement of the performance and the
manufacturing costs. In Fig. 3, the first space 21 and the second space 22 are
partitioned off by the first partition 35; however, the advantage can still be obtained
even when the first space 21 and the second space 22 are defined by respective
separate headers.
20 [0052]
In addition, for example, the number of the outdoor units 201 and the number
of the indoor units 202 are each not limited to one, and a plurality of the outdoor units
201 and a plurality of the indoor units 202 may be provided in the air-conditioning
apparatus 200. In addition, the kind of refrigerant that circulates in the refrigeration
25 cycle circuit of the air-conditioning apparatus 200 is not limited to a specific one. For
example, as the refrigerant, R32 refrigerant, R410A refrigerant, and kinds of
refrigerant that include at least olefin-based refrigerant, propane, and dimethyl ether
(DME) and that each have a lower gas density than the gas density of the R32
refrigerant are present. Such kinds of refrigerants are capable of reducing the
30 discrepancy between the air velocity distribution and the refrigerant distribution that
20
would be caused by the pressure loss of gas refrigerant, thus further greatly
improving the performance.
[0053]
The first heat transfer tubes 3_1 and the second heat transfer tubes 3_2 of the
5 outdoor heat exchanger 10 are not limited to circular heat transfer tubes, and may be
various heat transfer tubes such as flat heat transfer tubes in which the major axis of
a section orthogonal to the axial direction of the first heat transfer tubes 3_1 and the
second heat transfer tubes 3_2 extends along the airflow direction. In particular, in a
configuration in which flat heat transfer tubes are directly inserted in the first
10 intermediate header 1, the passage diameter of the header in the vertical direction is
greater than the length of the major axis of the flat tubes, thus increasing the passage
sectional area. As a result, the flow velocity in the second space 22 is reduced to
increase the amount of the accumulation of the liquid refrigerant 104, whereby the
performance is greatly improved by the present configuration.
15 [0054]
In addition, as illustrated in Figs. 2, 3, and 5, the sum of the number of the first
heat transfer tubes 3_1 connected to the first space 21 and the number of the first
heat transfer tubes 3_1 connected to the second space 22 may be set equal to or
larger than the number of the heat transfer tubes connected to the third space.
20 [0055]
Fig. 9 is a schematic diagram illustrating an example of a refrigerant passage
configuration of the outdoor heat exchanger 10 according to Embodiment 1. As
illustrated in Fig. 9, the outdoor heat exchanger 10 is formed as a parallel flow
condenser in which two rows or more of headers are provided at opposite ends of
25 heat transfer tubes. The sum of the number of the first heat transfer tubes 3_1
connected to the first space 21 and the number of the first heat transfer tubes 3_1
connected to the second space 22 is larger than the number of the second heat
transfer tubes 3_2 connected to the third space 23. Such a configuration needs to
cause liquid refrigerant in the lower region in the first intermediate header 1 to flow
30 upward, thus achieving great improvement.
21
[0056]
In addition, as illustrated in Figs. 2, 3, and 5, the first connection pipe 31 which
causes the first space 21 and the third space 23 to communicate with each other are
provided below the average level of the first heat transfer tubes 3_1 connected to the
5 first space 21. The average level is the average of the levels, in the up-down
direction, of all the first heat transfer tubes 3_1 connected to the first space 21. In
such a configuration, it is possible to reduce occurrence of accumulation of the liquid
refrigerant in the first space 21, thus greatly improving the performance.
[0057]
10 However, even when the first connection pipe 31 is provided above the
average level of the first heat transfer tubes 3_1, liquid refrigerant flows out from the
first space 21 due to the siphon principle as long as the lower region of the first space
21 is provided above a lower region of the third space 23. Thus, the performance is
still improved.
15 [0058]
Therefore, in the outdoor heat exchanger 10 in Embodiment 1, it is possible to
reduce occurrence of a liquid accumulation on the lower side of the first intermediate
header 1 and the first heat exchange unit 11 in the direction of gravity. As in the
existing configuration in which the first intermediate header 1 does not include the first
20 partition 35, liquid refrigerant that has dripped from the upper side in the direction of
gravity in the first intermediate header 1 cannot be raised by only refrigerant in the
lowermost one of the heat transfer tubes in the direction of gravity and is accumulated
particularly at an intermediate load. In the configuration of the outdoor heat
exchanger 10 in Embodiment 1, the first partition 35 is provided in the first
25 intermediate header 1. Then, liquid-dominated refrigerant that has flowed from the
first space 21 via the first connection pipe 31 and gas-dominated refrigerant that has
flowed from the second space 22 via the second connection pipe 32 join together in
the third space 23 of the second intermediate header 2. Thus, occurrence of liquid
dripping in the third space 23 can be reduced by refrigerant in a plurality of second
30 heat transfer tubes 3_2. Therefore, it is possible to mix two-phase gas-liquid
22
refrigerant in the third space 23, while reducing occurrence of a liquid accumulation in
the outdoor heat exchanger 10, thus improving the cooling performance.
[0059]
Embodiment 2
5 Regarding Embodiment 2, matters that will not be particularly described
regarding Embodiment 2 are similar to matters in Embodiment 1, and regarding
Embodiment 2, components that have the same functions and configurations as in
Embodiment 1 will be denoted by the same reference signs.
[0060]
10 Fig. 10 is a vertical sectional view illustrating the first intermediate header 1 and
the second intermediate header 2 of the outdoor heat exchanger 10 according to
Embodiment 2.
[0061]
In the outdoor heat exchanger 10 according to Embodiment 2, in Embodiment
15 1, the second intermediate header 2 has the fourth space 24 which is located below
the third space 23, which is separated from the third space 23, and which
communicates with at least one of the second heat transfer tubes 3_2. The first
partition 35 by which the first space 21 and the second space 22 are partitioned off is
provided above the second partition 36 by which the third space 23 and the fourth
20 space 24 are partitioned off. The first partition 35 and the second partition 36 are
plate-like components.
[0062]
Since the outdoor heat exchanger 10 is formed in the above manner, it
promotes the flow of liquid refrigerant from the first space 21 into the third space 23
25 via the first connection pipe 31 due to the head difference between the first partition
35 and the second partition 36, thus reducing a liquid accumulation in the first space
21. As a result, the cooling performance of the air-conditioning apparatus 200 is
improved.
[0063]
30 Embodiment 3
23
Regarding Embodiment 3, matters that will not be particularly described in
Embodiment 3 are similar to those in in Embodiment 1 and/or Embodiment 2, and
components that have the same functions and configurations as those in Embodiment
1 and/or Embodiment 2 will be denoted by the same reference signs.
5 [0064]
Fig. 11 is a vertical sectional view illustrating the first intermediate header 1 and
the second intermediate header 2 of the outdoor heat exchanger 10 according to
Embodiment 3. Unlike Embodiment 2, in Embodiment 3, the second outlet 32_1 of
the second connection pipe 32, which is located in the second space 22 of the first
10 intermediate header 1, is provided at a higher level than the second partition 36 by
which the third space 23 and the fourth space 24 are separated from each other.
The second connection pipe 32 causes the second space 22 of the first intermediate
header 1 and the third space 23 of the second intermediate header 2 to communicate
with each other.
15 [0065]
Since the outdoor heat exchanger 10 is formed in the above manner, it reduces
occurrence of the backflow 105 of the liquid refrigerant (see Fig. 4) into the second
space 22 due to the head difference between the second partition 36 and the second
outlet 32_1 in the second space 22, thus improving the cooling performance of the
20 air-conditioning apparatus 200
[0066]
Embodiment 4
Regarding Embodiment 4, matters that will not be particularly described are
similar to those in Embodiment 3, and components that have the same functions and
25 configurations as those in Embodiment 3 will be denoted by the same reference
signs.
[0067]
Fig. 12 is a top sectional view of the first intermediate header 1 and the second
intermediate header 2 according to Embodiment 4 that is obtained as viewed from the
30 above. Fig. 13 is an enlarged sectional view taken along line A-A in Fig. 12.
24
[0068]
In Fig. 12, the reference sign 71 denotes the central axis of the first
intermediate header 1 in the direction in which the first intermediate header 1
extends, and the reference sign 72 denotes the central axis of the second
5 intermediate header 2 in the direction in which the second intermediate header 2
extends. The reference sign 73 denotes the central axis of the connection pipe.
Two dashed lines extending from the central axis 72 of the second intermediate
header 2 in the direction in which the second intermediate header 2 extends indicate
a range in which a pipe wall 38 of the first intermediate header 1 is visible. In Fig.
10 13, the reference sign 111 denotes a refrigerant flow from the first space 21 into the
third space 23, and the reference sign 112 denotes the flow of the refrigerant from the
second space 22 into the third space 23.
[0069]
In Embodiment 4, the first outlet 31_1 is provided in part of the pipe wall 38 of
15 the first intermediate header 1 in the range in which the first intermediate header 1 is
visible as viewed from the central axis 72 of the second intermediate header 2 in the
direction in which the first intermediate header and the second intermediate header 2
extend. That is, the first outlet 31_1 is provided in part of the pipe wall 38 of the first
intermediate header 1 that is closer to the second intermediate header 2.
20 [0070]
In the first intermediate header 1 which is formed as in Embodiment 4, the path
length of the first connection pipe 31 from the first space 21 to the third space 23 is
shortened, thereby promoting the flux of the refrigerant flow 111, and thus reducing
accumulation of the liquid refrigerant in the first space 21. In addition, the path
25 length of the second connection pipe 32 from the second space 22 to the third space
23 is shortened, thereby carrying refrigerant into the third space 23 without greatly
reducing an inertial force of the refrigerant flow 112. It is therefore possible to supply
a large amount of gas-dominated refrigerant in the opposite direction to the direction
of gravity in the third space 23, thus enabling the refrigerant to be distributed
30 depending on an air velocity distribution in the top blowing housing.
25
[0071]
Fig. 14 is an enlarged sectional view taken along line A-A in Fig. 12 and
illustrating a first modification of the first intermediate header 1 and the second
intermediate header 2 in Embodiment 4.
5 [0072]
In the modification of Embodiment 4 which is provided as illustrated in Fig. 14,
in the height direction, the first outlet 31_1 which is located in the first space 21 of the
first intermediate header 1 and which allows the refrigerant to flow into the third space
23 is located at the same position as or at a higher level than the first inlet 33_1 which
10 is located in the third space 23 of the second intermediate header 2 and which allows
the refrigerant to flow from the first space 21.
[0073]
In the first intermediate header 1 which is formed as in the present
modification, the flux of the refrigerant flow 111 is promoted due to the position of the
15 first outlet 31_1 in the height direction and the head difference between the first outlet
31_1 and the first inlet 33_1, thus reducing accumulation of the liquid refrigerant in
the first space 21. As a result, the condenser performance is improved, thus
improving the cooling performance of the air-conditioning apparatus 200.
[0074]
20 In addition, in the modification of Embodiment 4 which is provided illustrated in
Fig. 14, in the height direction, the second outlet 32_1 which is located in the second
space 22 of the first intermediate header 1 and which allows the refrigerant flows into
the third space 23 is provided at a higher level than the second partition 36 of the
second intermediate header 2.
25 [0075]
Since the second outlet 32_1 is provided at a higher level than the second
partition 36 in a direction parallel to the direction of gravity as in the present
modification, this configuration reduces occurrence of the backflow 105 of the liquid
refrigerant (see Fig. 4) from the third space 23 into the second space 22. As a
30 result, the condenser performance is improved, thus improving the cooling
26
performance of the air-conditioning apparatus 200. This improvement effect is great
particularly in the low-load operation in which the flow rate of the refrigerant is low.
[0076]
Fig. 15 is an enlarged sectional view taken along line A-A in Fig. 12 and
5 illustrating a second modification of the first intermediate header 1 and the second
intermediate header 2 according to Embodiment 4. As illustrated in Fig. 15, in the
second modification of Embodiment 4, the first outlet 31_1 and the second outlet
32_1 are separated from each other by the first partition 35. That is, the first
partition 35 is provided in the level range of an opening provided in the pipe wall of
10 the first intermediate header 1. A region of the opening that is located above the first
partition 35 is the first outlet 31_1, and a region of the opening that is located below
the first partition 35 is the second outlet 32_1.
[0077]
The first connection pipe 31 and the second connection pipe 32 may be formed
15 integrally with each other to combine into a single pipe, as long as the first outlet 31_1
and the second outlet 32_1 are different outlets as in the present modification. In the
present modification, liquid refrigerant located above the first partition 35 does not
need to be made to flow upward in the process of supplying refrigerant from the first
space 21 to the third space 23. It is therefore possible to reduce accumulation of the
20 liquid refrigerant in the first space 21. As a result, the condenser performance is
improved, thus improving the cooling performance of the air-conditioning apparatus
200. This improvement effect is great particularly in the low-load operation in which
the flow rate of the refrigerant is low.
[0078]
25 The embodiments are described above as examples and their descriptions are
not intended to limit the claims. The embodiments can be put into practice in other
various forms and can be variously omitted, replaced, and modified without departing
from the gist of the embodiments. The embodiments and modifications thereof are
encompassed in the scope and the gist of the embodiments.
30 Reference Signs List
27
[0079]
1: first intermediate header, 2: second intermediate header, 3_1: first heat
transfer tube, 3_2: second heat transfer tube, 4: fin, 10: outdoor heat exchanger, 11:
first heat exchange unit, 12: second heat exchange unit, 13: fan, 14: compressor, 16:
5 indoor heat exchanger, 17: expansion device, 18: refrigerant pipe, 21: first space, 22:
second space, 23: third space, 24: fourth space, 31: first connection pipe, 31_1: first
outlet, 32: second connection pipe, 32_1: second outlet, 33_1: first inlet, 34_1:
second inlet, 35: first partition, 36: second partition, 38: pipe wall, 71: central axis of
first intermediate header 1 in extending direction of first intermediate header 1, 72:
10 central axis of second intermediate header 2 in extending direction of second
intermediate header 2, 73: central axis of connection pipe, 90: direction of gravity,
100: liquid refrigerant, 101: gas refrigerant, 102: liquid-dominated refrigerant, 103:
gas-dominated refrigerant, 104: accumulation of the liquid refrigerant, 105: backflow
of liquid refrigerant, 111: refrigerant flow from first space into third space, 112:
15 refrigerant flow from second space into third space, 200: air-conditioning apparatus,
201: outdoor unit, 202: indoor unit, 203: top blowing housing, 300: air velocity
distribution, AF: flow direction of air

WE CLAIM:
[Claim 1]
A heat exchanger comprising:
a first heat exchange unit; and
5 a second heat exchange unit,
the first heat exchange unit including
a first intermediate header extending in a direction of gravity,
a first heat transfer tube connected to the first intermediate header, and
used in heat exchange between refrigerant and air, and
10 a first partition that partitions an interior of the first intermediate header
into a first space and a second space located below the first space,
the second heat exchange unit including
a second intermediate header provided alongside of the first heat
exchange unit and on a windward side relative to the first heat exchange unit, the
15 second intermediate header extending in the direction of gravity,
a second heat transfer tube connected to the second intermediate
header and used in heat exchange between the refrigerant and the air, and
a second partition that partitions an interior of the second intermediate
header into a third space and a fourth space located below the third space,
20 wherein a plurality of first heat transfer tubes including the first heat transfer
tube are provided, and include
a first heat transfer tube that extends to communicate with the first
space, and
a first heat transfer tube that extends to communicate with the second
25 space,
the first intermediate header defines the first space and has a first outlet
through which the refrigerant flows out,
the first intermediate header defines the second space and has a second outlet
through which the refrigerant flows out, and
29
the second intermediate header is connected to the first intermediate header
and has
a first inlet through which the refrigerant flows from the first outlet into the
third space, and
5 a second inlet through which the refrigerant flows from the second outlet
into the third space.
[Claim 2]
The heat exchanger of claim 1, wherein the first heat transfer tube and the
second heat transfer tube are flat heat transfer tubes in which a major axis of each of
10 sections orthogonal to an axial direction of the first heat transfer tube and the second
heat transfer tube extends along an airflow direction.
[Claim 3]
The heat exchanger of claim 1 or 2, wherein
the second heat transfer tube extends to communicate with the third space,
15 and
a sum of the number of the first heat transfer tubes which extend to
communicate with the first space and the number of the first heat transfer tubes which
extend to communicate with the second space is larger than the number of second
heat transfer tubes including the second heat transfer tube.
20 [Claim 4]
The heat exchanger of any one of claims 1 to 3, further comprising
a first connection pipe extending to communicate with the first outlet and the
first inlet,
wherein the first connection pipe is provided below an average level of levels of
25 the first heat transfer tubes which extend to communicate with the first space.
[Claim 5]
The heat exchanger of any one of claims 1 to 4, wherein the first partition is
provided above the second partition.
30
[Claim 6]
The heat exchanger of any one of claims 1 to 5, wherein the second outlet is
provided above the second partition.
[Claim 7]
5 The heat exchanger of claim 4, further comprising a second connection pipe
extending to cause the second outlet and the second inlet to communicate with each
other.
[Claim 8]
The heat exchanger of any one of claims 1 to 7, wherein the first outlet is
10 provided in part of a pipe wall of the first intermediate header that is located in a
range in which the first intermediate header is visible from a central axis of the second
intermediate header in a direction in which the first intermediate header extends.
[Claim 9]
The heat exchanger of any one of claims 1 to 8, wherein the first outlet is
15 provided at a higher level than the first inlet.
[Claim 10]
The heat exchanger of any one of claims 1 to 9, wherein the refrigerant include
R32 refrigerant, 410A refrigerant, or refrigerant which includes at least olefin-based
refrigerant, propane, and dimethyl ether (DME) and which has a lower gas density
20 than a gas density of the R32 refrigerant.
[Claim 11]
An air-conditioning apparatus comprising the heat exchanger of any one of
claims 1 to 10.
[Claim 12]
25 The air-conditioning apparatus of claim 11, further comprising:
a fan configured to send air upward; and
31
a top blowing housing having an air outlet through which air sent to the fan
flows out,
wherein the heat exchanger is mounted in the housing