U.S. patent application number 14/761366 was filed with the patent office on 2015-12-17 for refrigerant distribution device and a heat pump apparatus using the same refrigerant distribution device.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Keisuke HOKAZONO, Takuya MATSUDA, Atsushi MOCHIZUKI, Takashi NAKAJIMA, Hiroki OKAZAWA, Wataru SUZUKI. Invention is credited to Keisuke HOKAZONO, Takuya MATSUDA, Atsushi MOCHIZUKI, Takashi NAKAJIMA, Hiroki OKAZAWA, Wataru SUZUKI.
Application Number | 20150362222 14/761366 |
Document ID | / |
Family ID | 51227057 |
Filed Date | 2015-12-17 |
United States Patent
Application |
20150362222 |
Kind Code |
A1 |
MATSUDA; Takuya ; et
al. |
December 17, 2015 |
REFRIGERANT DISTRIBUTION DEVICE AND A HEAT PUMP APPARATUS USING THE
SAME REFRIGERANT DISTRIBUTION DEVICE
Abstract
A refrigerant distribution device is provided for distributing
refrigerant to a plurality of heat transfer tubes that constitute a
heat exchanger. The refrigerant distribution device includes a
first distribution device dividing refrigerant into a plurality of
portions, and a plurality of two-way branch pipes each dividing
refrigerant divided by the first distribution device into two
portions to flow into two of the plurality of heat transfer
tubes.
Inventors: |
MATSUDA; Takuya; (Tokyo,
JP) ; HOKAZONO; Keisuke; (Tokyo, JP) ;
OKAZAWA; Hiroki; (Tokyo, JP) ; SUZUKI; Wataru;
(Tokyo, JP) ; NAKAJIMA; Takashi; (Tokyo, JP)
; MOCHIZUKI; Atsushi; (Tokyo, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MATSUDA; Takuya
HOKAZONO; Keisuke
OKAZAWA; Hiroki
SUZUKI; Wataru
NAKAJIMA; Takashi
MOCHIZUKI; Atsushi |
|
|
US
US
US
US
US
US |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Tokyo
JP
|
Family ID: |
51227057 |
Appl. No.: |
14/761366 |
Filed: |
January 22, 2013 |
PCT Filed: |
January 22, 2013 |
PCT NO: |
PCT/JP2013/051146 |
371 Date: |
July 16, 2015 |
Current U.S.
Class: |
62/324.1 ;
165/174 |
Current CPC
Class: |
F28F 2275/04 20130101;
F28D 1/0476 20130101; F25B 39/028 20130101; F25B 13/00 20130101;
F25B 41/00 20130101; F28F 9/26 20130101 |
International
Class: |
F25B 13/00 20060101
F25B013/00; F25B 41/00 20060101 F25B041/00 |
Claims
1. A refrigerant distribution device for distributing refrigerant
to a plurality of heat transfer tubes that constitute a heat
exchanger, the refrigerant distribution device comprising: a first
distribution device dividing refrigerant into a plurality of
portions; and a plurality of second distribution devices each
dividing refrigerant divided by the first distribution device into
two portions to flow into two of the plurality of heat transfer
tubes.
2-9. (canceled)
10. A heat pump apparatus comprising a refrigerant distribution
device for distributing refrigerant to a plurality of heat transfer
tubes that constitute a heat exchanger, the refrigerant
distribution device including a first distribution device dividing
refrigerant into a plurality of portions, and a plurality of second
distribution devices each dividing refrigerant divided by the first
distribution device into two portions to flow into two of the
plurality of heat transfer tubes.
11. The refrigerant distribution device of claim 1, wherein the
first distribution device is constituted by a distributor.
12. The refrigerant distribution device of claim 1, wherein a part
of each of the plurality of second distribution devices is formed
by performing bulge-forming process.
13. The refrigerant distribution device of claim 1, wherein each of
the plurality of second distribution devices includes a U-bend
section formed in U-shape having two arms extending in parallel to
each other and a straight inflow section formed on one of the two
arms of the U-bend section.
14. The refrigerant distribution device of claim 13, wherein the
straight inflow section is formed by performing bulge-forming
process on the one of the two arms.
15. The refrigerant distribution device of claim 13, wherein each
of the plurality of second distribution devices is formed such that
the straight inflow section is formed to be inclined to the one of
the two arms.
16. The refrigerant distribution device of claim 15, wherein an
inclined angle of the straight inflow section to the one of the two
arms on which the straight inflow section is formed is determined
depending on thermal load distribution of each path of the heat
exchanger.
17. The refrigerant distribution device of claim 15, wherein the
inclined angle of the straight inflow section to the one of the two
arms on which the straight inflow section is formed is 90
degrees.
18. The refrigerant distribution device of claim 13, wherein the
one of the two arms on which the straight inflow section is formed
includes an inwardly depressed recess adjacent to a wall surface
against which refrigerant flowing from the straight inflow section
collides.
19. The refrigerant distribution device of claim 12, wherein the
first distribution device is constituted by a distributor or a
header.
20. The refrigerant distribution device of claim 1, further
comprising a plurality of third distribution devices provided
between the first distribution device and the plurality of second
distribution devices to each divide refrigerant divided by the
first distribution device into two portions to flow into adjacent
two of the plurality of second distribution devices.
Description
CROSS REFERENCE TO RELATED APPLICATION
[0001] This application is a U.S. national stage application of
PCT/JP2013/051146 filed on Jan. 22, 2013, the content of which is
incorporated herein by reference.
TECHNICAL FIELD
[0002] The present invention relates to refrigerant distribution
devices.
BACKGROUND
[0003] When a plurality of refrigerant flow paths are provided in a
heat exchanger, which serves as a condensor or an evaporator of a
heat pump apparatus such as an air conditioner and a refrigerator,
a refrigerant distribution device that distributes the refrigerant
to the respective paths is necessary on an inlet side of the
refrigerant.
[0004] A distributor is conventionally used as a refrigerant
distribution device so that refrigerant distributed by the
distributor flows into the respective heat transfer tubes of the
heat exchanger by capillary tubes (for example, see Patent
Literature 1).
PATENT LITERATURE
[0005] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2008-121984 (page 4, FIG. 1)
[0006] As a technique of improving heat exchange efficiency in a
heat exchanger, using a circular tube having a small diameter or a
flat tube in which a plurality of refrigerant flow paths are formed
as a heat transfer tube is known. As the diameter of the circular
tube decreases or the flat tube is used, the number of heat
transfer tubes used in one heat exchanger increases.
[0007] In Patent Literature 1, a plurality of heat transfer tubes
are connected to a distributor via capillary tubes that are
individually disposed at the ends of the heat transfer tubes, which
serve as inlet ports for refrigerant flowing from the outside, and
the number of paths of the heat exchanger and the number of the
capillary tubes are the same. As a result, as the number of heat
transfer tubes increases and thus the number of paths increases,
the number of capillary tubes also increases.
[0008] When the number of capillary tubes increases, there are
problems that the capillary tubes are not easily routed and an
installation space of the capillary tubes mounted on an actual
machine increases. In addition, when the number of capillary tubes
increases, the cost also increases. Accordingly, it is required to
prevent the cost increase due to use of heat transfer tubes having
small diameter or flat heat transfer tubes.
SUMMARY
[0009] The present invention is made to overcome such problems and
provides a refrigerant distribution device that enables a reduction
in the number of connected capillary tubes, a compact installation
space of the capillary tubes mounted on an actual machine, and a
cost reduction, and a heat pump apparatus that uses this
refrigerant distribution device.
[0010] A refrigerant distribution device according to the present
invention distributes refrigerant to a plurality of heat transfer
tubes that constitute a heat exchanger. The refrigerant
distribution device includes a first distribution device dividing
refrigerant into a plurality of portions, and a plurality of second
distribution devices each dividing refrigerant divided by the first
distribution device into two portions to flow into two of the
plurality of heat transfer tubes.
[0011] According to the present invention, the number of connected
capillary tubes can be reduced, an installation space of the
capillary tubes mounted on an actual machine can be compact, and
the cost of the capillary tubes can be reduced.
BRIEF DESCRIPTION OF DRAWINGS
[0012] FIG. 1 is a schematic configuration diagram showing a state
in which a refrigerant distribution device according to Embodiment
1 of the present invention is connected to a heat exchanger.
[0013] FIG. 2 is perspective views of a two-way branch pipe of FIG.
1.
[0014] FIG. 3 is a perspective view of a circular tube-flat tube
joint.
[0015] FIG. 4 is configuration explanatory views of a two-way
branch pipe of the refrigerant distribution device according to
Embodiment 1 of the present invention.
[0016] FIG. 5 is a view showing a refrigerant circuit of a heat
pump apparatus that uses the refrigerant distribution device
according to Embodiment 1 of the present invention.
[0017] FIG. 6 is a view showing a configuration example in which
the refrigerant distribution device according to Embodiment 1 of
the present invention is connected to a heat exchanger for an
outdoor unit of an air conditioning apparatus that uses a flat tube
as a heat transfer tube.
[0018] FIG. 7 is an enlarged perspective view seen from the
backside of a connecting portion of the heat exchanger and the
refrigerant distribution device of FIG. 6.
[0019] FIG. 8 is a perspective view of the flat tube of FIG. 6.
[0020] FIG. 9 is a view showing a conventional example that does
not use a two-way branch pipe in a heat exchanger of three-line
arrangement configuration.
[0021] FIG. 10 is a configuration diagram of the refrigerant
distribution device according to Embodiment 2 of the present
invention.
[0022] FIG. 11 is views showing a third distribution device in the
refrigerant distribution device of FIG. 10.
[0023] FIG. 12 is configuration diagrams of the second distribution
device in the refrigerant distribution device according to
Embodiment 3 of the present invention.
[0024] FIG. 13 is configuration diagrams of the second distribution
device in the refrigerant distribution device according to
Embodiment 4 of the present invention.
[0025] FIG. 14 is an enlarged view of an essential part of FIG. 13
(A).
[0026] FIG. 15 is a configuration example in which a header is used
for a first distribution device.
DETAILED DESCRIPTION
Embodiment 1
[0027] FIG. 1 is a schematic configuration diagram showing a state
in which a refrigerant distribution device according to Embodiment
1 of the present invention is connected to a heat exchanger. In
FIG. 1 and the drawings described later, the same reference signs
refer to the same or corresponding elements throughout the whole
description. Further, the forms of the elements shown in the
description are for exemplary purposes only and the invention is
not limited to the description.
[0028] A heat exchanger 1 is a fin and tube heat exchanger that
includes a plurality of plate shaped fins 2 being stacked with
spaces therebetween and a plurality of heat transfer tubes 3 that
penetrate the plate shaped fins 2 in a stack direction and allow
refrigerant to flow therein. The heat transfer tubes 3 may be
circular tubes or flat tubes made of copper or aluminum. A
plurality of heat transfer tubes 3 are connected to a refrigerant
distribution device 10 at one end and a gas header 6 at the other
end.
[0029] Next, the refrigerant distribution device 10 connected to
this heat exchanger 1 will be described.
[0030] The refrigerant distribution device 10 includes a first
distribution device 20 and a plurality of two-way branch pipes 30
as a second distribution device. The first distribution device 20
is to uniformly distribute refrigerant that flows into the first
distribution device 20 in a state of gas-liquid two-phase into the
respective heat transfer tubes 3 of the heat exchanger 1.
Accordingly, in FIG. 1, a distributor is used as the first
distribution device 20.
[0031] A throttle mechanism such as an orifice is inserted in the
distributor such that the two-phase flow that flows therein becomes
a spray flow while passing through the orifice to facilitate
uniform distribution. The spray flow of refrigerant is uniformly
distributed to the respective capillary tubes 40. A throttle
mechanism such as an orifice may not be used in the distributor. It
is essential that a distributor capable of uniform distribution is
used as the first distribution device 20. The distributor may be
made of a material such as copper, aluminum and brass.
[0032] The capillary tube 40 has an inner diameter of approximately
3.5 mm and a length of approximately 1000 mm. These dimensions of
the capillary tube 40 are merely an example. The capillary tube 40
may be curved in a circular shape depending on the relationship
between the length and the installation space.
[0033] Further, an in-pipe pressure loss can be adjusted based on
the specification (inner diameter, length) of the capillary tubes
40, thus a branch flow rate from the first distribution device 20
to each of the two-way branch pipes 30 can be adjusted. An air
speed of an air-sending fan (not shown in the figure) that sends
air to the heat exchanger 1 is not necessarily uniform across the
entire surface of the heat exchanger 1, and an air speed
distribution may be present. For example, when an air-sending fan
is disposed in the upper part of the heat exchanger 1, the air
speed is faster in the upper part of the heat exchanger 1 than in
the lower part.
[0034] When the heat exchanger 1 is used as an evaporator, the
refrigerant passing through a part in which the air speed is fast
tends to be easily evaporated and dried compared with the
refrigerant passing through a part in which the air speed is slow.
Accordingly, when the same amount of refrigerant flows into the
respective heat transfer tubes 3, the refrigerant passing through a
part in which the air speed is fast has a quality higher than the
refrigerant passing through a part in which the air speed is slow.
This causes variation in refrigerant state at the exit of the heat
exchanger, and the refrigerant state fails to be stabilized.
Therefore, it is required that a larger amount of refrigerant flows
into the heat transfer tube located in a part in which the air
speed is fast. As described above, when adjustment of branch flow
rate is necessary, the branch flow rate can be adjusted by
adjusting the specification of the capillary tubes 40.
[0035] The two-way branch pipes 30 are connected to the end of the
capillary tubes 40 on the opposite side to the first distribution
device 20. Using the two-way branch pipes 30 allows the refrigerant
to be distributed to the number of branches (the number of paths)
of 2.times.A, where A is the number of branches of the first
distribution device 20 and the number of capillary tubes 40. A
configuration of the two-way branch pipe 30 will be described
below.
[0036] FIG. 2 is a perspective view of the two-way branch pipe of
FIG. 1.
[0037] The two-way branch pipe 30 includes a U-bend section 31
formed by bending a circular tube in U-shape and a straight inflow
section 35. The U-bend section 31 includes a connection 32 and two
arms 33 and 34 extending from each end of the connection 32 in
parallel to each other. The straight inflow section 35 is formed by
performing bulge-forming process on one of the two arms 33 and 34
(in this example, the arm 34) of the U-bend section 31. In this
example, the straight inflow section 35 is disposed on the arm 34.
Bulge-forming process is a method for forming a hollow shape, in
which a pipe-shaped material is set in a mold of a press and then
clamped, and after that, while the material is filled with a liquid
of high pressure, the material is compressed in the axial direction
so that the both ends are forced toward each other, thereby
allowing the material to be expanded into the shape of the mold
cavity.
[0038] The straight inflow section 35 of the two-way branch pipe 30
constituted as described above is connected to one end of an
L-shaped pipe 36, which is bent in L-shape, while the other end of
the L-shaped pipe 36 is connected to the capillary tube 40. The
opening ports A and B of the two arms 33 and 34 of the two-way
branch pipe 30 are connected to the heat transfer tubes 3 of the
heat exchanger 1. In connecting the two arms 33 and 34 and the heat
transfer tubes 3, the heat transfer tubes 3 are directly connected
when they are circular tubes, and the heat transfer tubes 3 are
connected via circular tube-flat tube joints 4 of FIG. 3 when they
are flat tubes. Further, the two-way branch pipe 30 is connected to
the heat exchanger 1 so that the two arms 33 and 34 extend in a
parallel direction and the refrigerant flowing from the straight
inflow section 35 to the arm 34 is branched and flows in the
horizontal direction. The reason will be described later.
[0039] In the right figure of FIG. 2, the dotted line arrow
indicates the flow of refrigerant in the case where the heat
exchanger 1 is used as an evaporator, and in the two-way branch
pipe 30, the refrigerant flowing from the capillary tube 40 flows
into the straight inflow section 35 via the L-shaped pipe 36. The
refrigerant flowing into the straight inflow section 35 is branched
into the arm 33 and the arm 34, each of which flows into the
respective heat transfer tubes 3.
[0040] As described above, as the two-way branch pipe 30 allows the
introduced refrigerant to be branched into two flows to the
respective heat transfer tubes 3, the number of capillary tubes 40
can be reduced to half compared with the configuration in which the
capillary tubes 40 are directly connected to the respective heat
transfer tubes 3. Accordingly, using the refrigerant distribution
device 10 of Embodiment 1 can improve installability of the
capillary tubes 40.
[0041] In addition to the improvement in instability of the
capillary tubes 40, the two-way branch pipe 30 is required to have
a function of uniformly distributing the refrigerant flowing from
the capillary tubes 40 and allowing the refrigerant to flow into
the respective heat transfer tubes 3. In the refrigerant
distribution device 10, the first distribution device 20 can
uniformly distribute the refrigerant into the respective capillary
tubes 40, and it is also required for the two-way branch pipes 30
to uniformly distribute the refrigerant so that the refrigerant
flows into the respective heat transfer tubes of the heat exchanger
1 while remaining in the uniformly distributed state.
[0042] The refrigerant that has passed an expansion valve of the
heat pump apparatus and the refrigerant at an inlet of the
evaporator is generally in a state of gas-liquid two-phase flow
made up of gas refrigerant and liquid refrigerant, causing density
distribution in a cross section of the refrigerant flowing in
pipes. For example, when a pipe has a curve, a biased flow occurs
due to an effect of centrifugal force, which causes the flowing
liquid refrigerant to be biased to one side of the inner surface of
the pipe. That is, two-phase refrigerant is separated into gas and
liquid phases.
[0043] Therefore, when the heat exchanger is used as an evaporator,
it is required for the refrigerant distribution device located on
the inflow side of the refrigerant to have a function of preventing
the above biased flow from being generated and gas and liquid
phases from being separated. Further, it is required for the
refrigerant distribution device to have a function of distributing
the refrigerant in a state of being uniformly mixed while the ratio
of the gas and liquid mass flow rate at the inlet of the
refrigerant distribution device remains to be equal to the ratio of
the gas and liquid mass flow rate at the outlet of the refrigerant
distribution device. Moreover, as described above, as the number of
paths increases by decreasing the diameter of the circular tube or
flattening the tube, distributing uniform flow rate of refrigerant
to the respective paths becomes a more important matter.
[0044] A configuration used in the two-way branch pipes 30 for
uniformly distributing the refrigerant will be described below.
[0045] FIG. 4 is configuration explanatory views of the two-way
branch pipe of the refrigerant distribution device according to
Embodiment 1 of the present invention. FIG. 4 (a) is a front view
of the two-way branch pipe 30 and FIG. 4 (b) is a side view of FIG.
4 (a).
[0046] In the two-way branch pipe 30, the straight inflow section
35 is formed by bulge-forming such that an angle .theta..sub.1
between a tube axis X1 of the straight inflow section 35 and a tube
axis X2 of the arm 34 is 90 degrees.
[0047] When the angle .theta..sub.1 deviates from 90 degrees by 10
degrees or more, the refrigerant flowing from the straight inflow
section 35 obliquely collides against a portion of the arm 34 that
faces the straight inflow section 35 and generates a biased flow,
leading to deterioration of heat exchange efficiency. Therefore,
the angle .theta..sub.1 is formed to be 90 degrees. It should be
noted the angle is not limited to be exact 90 degrees, and may be
slightly deviated.
[0048] It is further effective for uniform distribution that the
straight inflow section 35 has the length of 5 mm or more. This
point will be described below. The two-phase flow of refrigerant
becomes a state in which the liquid phase of the refrigerant is
biased to one side in the capillary tube 40. Providing an approach
section that extends until a position at which the refrigerant
collides against the two-way branch and has 20 times or more of the
inner diameter allows for a sufficiently stable flow. However, in
Embodiment 1, ensuring a configuration with the approach section
having 20 times or more of the inner diameter is difficult.
Accordingly, Embodiment 1 ensures the length of 5 mm or more for
the straight inflow section 35 and the length of 15 mm or more (two
times or more of the inner diameter) together with the length of
the horizontal section of the capillary tube 40 or the L-shaped
pipe 36.
[0049] An experiment revealed that ensuring these dimensions allows
a liquid film of the two-phase flow of refrigerant flowing into the
straight inflow section 35 to be uniformly distributed in the pipe
so that a stable annular flow is provided. This annular flow
vertically collides against a collision wall 34a that faces the
straight inflow section 35 and then can be uniformly distributed
regardless of the amount of circulation because the branching
directions after collision are horizontal, being free from the
effect of gravity.
[0050] When the straight inflow section 35 is less than 5 mm, the
gas-liquid two-phase flow is affected by a curve of the capillary
tube 40 and becomes a state in which the liquid surface is biased
in the pipe of the straight inflow section 35. In this case, the
gas-liquid two-phase flow into the straight inflow section 35 is
biased by an effect of the biased liquid surface and fails to be
uniformly distributed in the two-way branch pipe 30, thereby
compromising heat exchange efficiency.
[0051] As described above, the two-way branch pipe 30 preferably
has the angle .theta..sub.1 of 90 degrees between the arm 34 and
the straight inflow section 35 and the length of the straight
inflow section 35 of 5 mm or more.
[0052] As described above, the straight inflow section 35 of the
two-way branch pipe 30 is formed by bulge-forming. Using the
bulge-forming process allows for a stable processing of the shape
of 90 degrees for the angle .theta..sub.1 and ensures the length of
5 mm or more for the straight inflow section 35. Bulge-forming
process can be applied to not only a straight pipe but also a
curved pipe, and further, the straight inflow section 35 can be
formed to have a long length while preventing the wall thickness
from being decreased.
[0053] The two-way branch pipe 30 and the capillary tube 40 can be
connected by inserting the L-shaped pipe 36 or the capillary tube
40 having an outer diameter smaller than an inner diameter of an
inlet port of the bulge-formed straight inflow section 35 in the
inlet port of the bulge-formed straight inflow section 35 and
brazing thereto. This provides stable manufacture without
defective. On the other hand, when the straight inflow section 35
is formed without using bulge-forming, the straight inflow section
35 has a small length and a small wall thickness. Consequently,
when the L-shaped pipe 36 or the capillary tube 40 is connected to
the straight inflow section 35, the angle .theta..sub.1 deviates
from 90 degrees by a large amount. Further, in brazing connection,
a part of the straight inflow section 35 is to be brazed, and
stable brazing cannot be performed due to a small wall thickness
and small length of the connection.
[0054] Although an angle .theta..sub.2 between the straight inflow
section 35 and the tube axis X2 of the arm 34 may be any degrees,
the angle .theta..sub.2 herein is 90 degrees as shown in FIG. 2.
The reason will be described below. As the diameter of the heat
transfer tube 3 decreases and the heat transfer tube 3 is
flattened, flow resistance of air decreases. Accordingly, the heat
transfer tubes 3 are designed to have narrow arrangement pitch, and
the mounting density of the heat transfer tubes 3 is increased. As
described above, using the two-way branch pipe 30 can improve
instability of the capillary tubes 40. In addition to that,
providing the angle .theta..sub.2 of the straight inflow section 35
of the two-way branch pipe 30 of 90 degrees (shown in FIG. 4) can
further improve connectivity of the capillary tubes 40.
[0055] To curve a pipe without making deformation and creases, a
curvature R that is twice to three times of the inner diameter is
necessary, and in the case where the angle .theta..sub.2 is 0
degree, the L-shaped pipe 36 or the capillary tube 40 interferes
with the two-way branch pipe 30. Accordingly, in the case where the
angle .theta..sub.2 is 0 degree, when the mounting density of the
heat transfer tubes 3 is increased, it is difficult to connect the
capillary tube 40 or the L-shaped pipe 36 to the straight inflow
section 35. With the angle .theta..sub.2 of 90 degrees, the
connection with the capillary tube 40 or the L-shaped pipe 36 comes
to the direction of air flow, which does not interfere with the
two-way branch pipe 30, thereby improving connectivity.
[0056] The advantage of the L-shaped pipe 36 will be described
below. The L-shaped pipe 36 and the straight inflow section 35 of
the two-way branch pipe 30 are initially connected by brazing, then
each of the opening ports A and B are connected to the circular
tube-flat tube joints 4 by brazing, and then the L-shaped pipe 36
and the capillary tube 40 are connected by brazing. This procedure
allows for a stable manufacturing process having a low defective
rate. The reason will be as described below. That is, the above
connection by brazing is performed by a burner, and since the
L-shaped pipe 36 and the capillary tube 40 are connected by brazing
at last, other pipes are less likely to be exposed to the flame of
burner.
[0057] Further, by using the L-shaped pipe 36, it becomes easy to
provide the angle .theta..sub.1, at which refrigerant flowing into
the two-way branch pipe, of 90 degrees and provide a long approach
distance for flowing into the two-way branch pipe, thereby
improving uniform distribution. In the case where the L-shaped pipe
36 is not used, the capillary tube 40 is directly connected to the
straight inflow section 35 of the two-way branch pipe 30.
Consequently, as the capillary tube 40 is long, unstable, and
non-easily routed, the angles .theta..sub.1, at which refrigerant
flowing into the two-way branch pipe 30, tends to largely vary.
[0058] In the above description, the straight inflow section 35 of
the two-way branch pipe 30 is 5 mm or more. However, since it is
essential to provide a straight flow path of 10 mm or more, it is
also possible that a sum of the L-shaped pipe 36 and the straight
inflow section 35 is 10 mm or more.
[0059] FIG. 5 is a view showing a refrigerant circuit of a heat
pump apparatus that uses the refrigerant distribution device
according to Embodiment 1 of the present invention.
[0060] The heat pump apparatus 60 includes a compressor 61, a
condensor 62 (heat exchanger 1), an expansion valve 63 as a
depressurizing device and an evaporator 64 (heat exchanger 1). The
gas refrigerant ejected from the compressor 61 flows into the
condensor 62, exchanges heat with air passing through the condensor
62, becomes a high pressure liquid refrigerant and flows out from
the condensor 62. The high pressure liquid refrigerant out of the
condensor 62 is depressurized by the expansion valve 63, becomes a
low pressure gas-liquid two-phase refrigerant, and flows into the
evaporator 64. The low pressure gas-liquid two-phase refrigerant
flowing into the evaporator 64 exchanges heat with air passing
through the evaporator 64, becomes a low pressure gas refrigerant,
and is suctioned back into the compressor 61.
[0061] Referring to FIGS. 1 and 5, an operation in the case where
the heat exchanger 1 is used as an evaporator will be described. In
FIG. 1, the solid arrow indicates a flow of refrigerant in the case
where the heat exchanger 1 is used as an evaporator.
[0062] First, the gas-liquid two-phase refrigerant flow out of the
expansion valve 63 flows into the first distribution device 20 and
becomes a spray flow. The spray flow of the refrigerant is
uniformly distributed to flow into the respective capillary tubes
40. After passing through the respective capillary tubes 40, the
refrigerant flows into the two-way branch pipes 30 and flows out
while being uniformly distributed into two branched flows as
described above, each of which flows into the heat transfer tube 3.
The refrigerant flowing into the respective heat transfer tubes 3
exchanges heat with air and becomes a gas state, and is then
collected in the gas header 6. The refrigerant collected in the gas
header 6 is suctioned into the compressor 61.
[0063] Referring to FIGS. 1 and 5, an operation in the case where
the heat exchanger 1 is used as a condensor will be described. In
FIG. 1, the dotted arrow indicates a flow of refrigerant in the
case where the heat exchanger 1 is used as a condensor.
[0064] In the case of condensor, the refrigerant flows in the
direction opposite to the case of the evaporator, and the gas
refrigerant flow out of the compressor 61 flows into the gas header
6. The refrigerant flowing into the gas header 6 flows into the
respective heat transfer tubes 3 while being uniformly distributed
in the gas header 6. A distributor or the like is not necessary
since the refrigerant can be uniformly distributed without
difficulty when the refrigerant is in a gas state, and the gas
header 6 constituted by a cylindrical hollow tube is used.
[0065] After exchanging heat with air, the refrigerant flowing into
the respective heat transfer tubes 3 flows through the two-way
branch pipes 30, the capillary tubes 40 and the first distribution
device 20 in sequence. Then, the refrigerant is collected in the
first distribution device 20, and flows into the expansion valve
63.
[0066] Next, a specific example of pipe connection using the
refrigerant distribution device 10 according to Embodiment 1 will
be described.
[0067] FIG. 6 is a view showing a configuration example in which
the refrigerant distribution device according to Embodiment 1 of
the present invention is connected to a heat exchanger for an
outdoor unit of an air conditioning apparatus that uses a flat tube
as a heat transfer tube. FIG. 7 is an enlarged perspective view
seen from the backside of a connecting portion of the heat
exchanger and the refrigerant distribution device of FIG. 6. In
FIG. 7, shaded portions are the two-way branch pipes 30. FIG. 8 is
a perspective view of the flat tube of FIG. 6.
[0068] The heat exchanger 100 has a configuration in which heat
exchangers are arranged in three lines of an air flow direction,
and includes a plurality of plate shaped fins 2 being stacked with
spaces therebetween and a plurality of flat tube 3 that penetrate
the plate shaped fins 2 in a stack direction and allow refrigerant
to flow therein. The ends of a plurality of flat tubes 3 are
connected to bends 5, which are bent in a hairpin shape, and the
gas header 6 in addition to the two-way branch pipes 30. Further,
in this heat exchanger 100, since the flat tubes 3 are used as heat
transfer tubes, the flat tubes 3 are connected to the two-way
branch pipes 30 and the bends 5 via the circular tube-flat tube
joints 4.
[0069] Further, when the heat exchanger 100 is used as an
evaporator, a path configuration in the heat exchanger 100 is
constituted so that the refrigerant flows in a so-called parallel
flow in which refrigerant flows while turning back from upstream to
downstream with respect to an air flow direction. On the other
hand, when the heat exchanger 100 is used as a condensor, paths are
constituted so that the refrigerant flows in a so-called opposite
flow in which refrigerant flows while turning back from downstream
to upstream with respect to an air flow direction. Since the
refrigerant is sub-cooled in the condensor, the refrigerant
temperature decreases. Accordingly, the heat exchange efficiency in
the case where the heat exchanger 100 is used as a condensor can be
improved by constituting paths so that the refrigerant flows as an
opposite flow.
[0070] The plate shaped fin 2 is made of aluminum, and the flat
tube 3 and the plate shaped fin 2 are connected by in-furnace
brazing. In the case where the heat exchanger uses the heat
transfer tube of a circular tube, the heat transfer tube and the
plate shaped fin are connected by a mechanical pipe expansion
method, which causes a problem that heat exchange efficiency is
compromised because an air layer is present between the heat
transfer tube and the plate shaped fin. However, since the flat
tube 3 and the plate shaped fin 2 are connected by in-furnace
brazing, heat resistance between the flat tube 3 and the plate
shaped fin 2 becomes zero, thereby improving heat exchange
efficiency.
[0071] The flat tube 3 is made of aluminum and the inside of the
flat tube 3 is separated to form a plurality of passages 31a as
shown in FIG. 8 so that the refrigerant flows through the
respective passages 31a. The flat tube 3 can increase the amount of
refrigerant and a contact heat transfer area three times of those
of the circular tube.
[0072] Next, the case where the refrigerant distribution device 10
according to Embodiment 1 is used in the heat exchanger of
three-line arrangement is compared with the case where the
refrigerant distribution device 10 according to Embodiment 1 is not
used with reference to FIG. 7 and FIG. 9, respectively. FIG. 9 is a
view showing a conventional example that does not use a two-way
branch pipe in a heat exchanger of three-line arrangement
configuration.
[0073] As seen from the comparison of FIG. 7 and FIG. 9, using the
two-way branch pipe 30 can decrease the number of the capillary
tubes 40 to half of that in the conventional example.
[0074] According to Embodiment 1, as described above, the number of
capillary tubes 40 can be reduced by combining the capillary tube
40, which is an outflow pipe of the first distribution device 20,
with the two-way branch pipe 30 in the refrigerant distribution
device 10. As a result, when the capillary tube 40 is mounted on an
actual machine, installation space of the capillary tube 40 becomes
compact. Further, cost can be reduced by reducing the number of the
capillary tubes 40, and the actual machine can be inexpensively
configured.
[0075] Since the angle .theta..sub.1 between the arm 34 and the
straight inflow section 35 is 90 degrees, the refrigerant two-phase
flow vertically collides against the collision wall 34a, which
faces the inflow section. Further, branch directions after
collision are horizontal, and the refrigerant is not under the
effect of gravity and can be uniformly distributed regardless of
the amount of circulation. Since the straight inflow section 35 is
formed by bulge-forming process, stable processing of the shape of
90 degrees can be performed for the angle .theta..sub.1.
[0076] Further, since the straight inflow section 35 is 10 mm or
more, the refrigerant two-phase flow into the straight inflow
section 35 can be allowed to vertically collide against the
collision wall 34a as a stable annular flow, thereby preventing
variation in refrigerant distribution and allowing for uniform
distribution.
[0077] As described above, using the refrigerant distribution
device 10 allows for uniform distribution of the two-phase flow of
gas-liquid. Accordingly, specific heat exchange efficiency can be
sufficiently performed in the heat exchanger 1.
Embodiment 2
[0078] Embodiment 2 is provided for further reducing the number of
the capillary tubes 40. The following description focuses on a part
of Embodiment 2 that differs from Embodiment 1. Further, a
modification example that is applied to the same configuration as
that of Embodiment 1 is also applied to Embodiment 2.
[0079] FIG. 10 is a configuration diagram of the refrigerant
distribution device according to Embodiment 2 of the present
invention. In FIG. 10, (a) is a front view, and (b) is a cross
sectional view taken along the line A-A of (a). FIG. 11 is views
showing a third distribution device in the refrigerant distribution
device of FIG. 10. In FIG. 11, (a) is a front view of the
refrigerant distribution device 10A, (b) is a side view of (a), and
(c) is a bottom view of (a).
[0080] The refrigerant distribution device 10A of Embodiment 2 has
a configuration that includes a plurality of two-way branch pipes
50 as a third distribution device in addition to the first
distribution device 20 and the two-way branch pipes 30 as a second
distribution device of Embodiment 1. The two-way branch pipe 50 has
the same structural characteristics as those of the two-way branch
pipe 30 of Embodiment 1, and includes a U-bend section 51, which is
formed by bending the circular tube in U-shape, and the straight
inflow section 55. The U-bend section 51 includes a connection 52
and two arms 53 and 54 extending from each end of the connection 52
in parallel to each other. The straight inflow section 55 is formed
by performing bulge-forming process on one of the two arms 53 and
54 (in this example, the arm 54) of the U-bend section 51.
[0081] The straight inflow section 55 of the two-way branch pipe 50
is connected to the capillary tube 40, and the two arms 53 and 54
are each connected to the straight inflow section 35 of the
adjacent two-way branch pipe 30. Further, the two-way branch pipe
50 is also disposed so that the two arms 53 and 54 extend in a
parallel direction as similar to the two-way branch pipe 30 of
Embodiment 1.
[0082] The refrigerant distribution device 10A of Embodiment 2,
which is configured as described above, can obtain the same effect
as that of Embodiment 1 and the following effect. That is, since
the two-way branch pipes 50 are disposed as a third distribution
device, the number of capillary tubes 40 connected to the first
distribution device 20 can be reduced to half of that of Embodiment
1.
[0083] Since the two-way branch pipe 50 serves as an inflow pipe
for the refrigerant flowing out from the capillary tube 40, the
same function as that of the two-way branch pipe 30 of Embodiment 1
is required. That is, the function of uniformly distributing the
refrigerant out of the capillary tube 40 and allowing it to flow
into the respective heat transfer tubes 3 is required. Since the
two-way branch pipe 50 has the same configuration as that of the
two-way branch pipe 30, the refrigerant out of the straight inflow
section 55 of the two-way branch pipe 50 vertically collides
against a collision wall that is a wall surface facing the straight
inflow section 55 in the arm 54. Since branch directions after
collision are horizontal, the refrigerant is not under the effect
of gravity and can be uniformly distributed regardless of the
amount of circulation.
Embodiment 3
[0084] Embodiment 3 is directed to a refrigerant distribution
device that can adjust a distribution ratio of refrigerant. The
following description focuses on a part of Embodiment 3 that
differs from Embodiment 1. Further, in Embodiment 3, a modification
example that is applied to the same configuration as that of
Embodiment 1 is also applied to Embodiment 3.
[0085] FIG. 12 is configuration diagrams of the second distribution
device in the refrigerant distribution device according to
Embodiment 3 of the present invention. In FIG. 12, (a) is a front
view of the second distribution device, and (b) is a side view of
(a).
[0086] The refrigerant distribution device of Embodiment 3 has the
same configuration as that of Embodiment 1 except that a two-way
branch pipe 30A is disposed instead of the two-way branch pipe
30.
[0087] The two-way branch pipe 30 of Embodiment 1 forms the angle
.theta..sub.1 of 90 degrees with respect to the straight inflow
section 35 and the arm 34. On the other hand, the two-way branch
pipe 30A of Embodiment 3 has a configuration in which the angle
.theta..sub.1 is adjusted depending on a desired distribution
ratio. When the angle .theta..sub.1 is formed as the angle smaller
than 90 degrees, the flow rate of the refrigerant flowing in the
opening port A becomes larger than that of the opening port B,
while when the angle .theta..sub.1 is formed as the angle larger
than 90 degrees, the flow rate of the refrigerant flowing in the
opening port B becomes larger than that of the opening port A.
Accordingly, the straight inflow section 35 that requires angle
adjustment is formed by bulge-forming process as similar to
Embodiment 1. As a result of forming by bulge-forming process,
variation of the angles .theta..sub.1 can be reduced and the angle
.theta..sub.1 can be precisely formed at a predetermined angle.
Although the angle .theta..sub.2 may be any angle as similar to
Embodiment 1, 90 degrees is preferable in consideration of
connection to the capillary tubes 40.
[0088] The two-way branch pipe 30A is connected to the capillary
tube 40 at one end and the heat transfer tubes 3 at the other
ends.
[0089] As described above, an air speed of an air sending fan that
sends air to the heat exchanger 1 is not necessarily uniform across
the entire surface of the heat exchanger 1, and air speed
distribution is present. Such air speed distribution or difference
in the lengths of the refrigerant flow path for each of thermal
paths may cause difference in thermal load of the paths.
Accordingly, it is necessary that a larger amount of refrigerant
flows into one of the paths connected to the opening port A and the
opening port B that is, for example, having a faster air speed or a
larger number of heat transfer tubes and a longer length of flow
path. Therefore, the distribution ratio of refrigerant to the
opening port A and the opening port B is determined based on the
thermal load distribution of the paths in the heat exchanger 1, and
thus the angle .theta..sub.1 is determined.
[0090] By determining the angle .theta..sub.1 as described above,
the refrigerant flowing from the straight inflow section 35
collides against a surface facing the straight inflow section 35
with the angle .theta..sub.1 and is then distributed into the arm
33 and the arm 34 while the flow rate is adjusted depending on an
inclination angle .theta..sub.1. Then, the refrigerant of
distributed flow rate flows into the heat transfer tubes 3 of the
heat exchanger 1 via the opening port A and the opening port B.
[0091] As described above, according to Embodiment 3, the number of
capillary tubes 40 can be reduced as similar to Embodiment 1, and a
refrigerant distribution device that can adjust a distribution
ratio of refrigerant can be provided.
Embodiment 4
[0092] Embodiment 4 is also directed to a refrigerant distribution
device that can adjust a distribution ratio of refrigerant as
similar to Embodiment 3. The following description focuses on a
part of Embodiment 4 that differs from Embodiment 1. Further, a
modification example that is applied to the same configuration as
that of Embodiment 1 in Embodiment 4 is also applied to Embodiment
4.
[0093] FIG. 13 is configuration diagrams of the second distribution
device in the refrigerant distribution device according to
Embodiment 4 of the present invention. In FIG. 13, (A) shows a
configuration example of the two-way branch pipe 30B in which the
distribution ratio at the opening port B is larger than that at the
opening port A, and (B) shows a configuration example of the
two-way branch pipe 30B in which the distribution ratio at the
opening port A is larger than that at the opening port B. Further,
in FIGS. 13 (A) and (B), (a) is a front view of the two-way branch
pipe 30B, and (b) is a side view of (a). FIG. 14 is an enlarged
view of an essential part of FIG. 13 (A).
[0094] The refrigerant distribution device of Embodiment 4 has the
same configuration as that of Embodiment 1 except that the two-way
branch pipe 30B is disposed instead of the two-way branch pipe 30.
The two-way branch pipe 30B has an inwardly depressed recess 37 at
a position adjacent to the collision wall 34a. The remaining is the
same as Embodiment 1 including the facts that the straight inflow
section 35 is formed by bulge-forming process and that the angle
.theta..sub.2 can be any angle.
[0095] When the thermal load at the opening port B is higher, that
is, when the refrigerant flow rate should be larger at the opening
port B than at the opening port A, the recess 37 is formed at a
position close to the opening port A with respect to the collision
wall 34a in a tube axis direction of the U-bend section 31 as shown
in FIG. 13 (A). On the other hand, when the thermal load at the
opening port A is higher, that is, when refrigerant flow rate
should be larger at the opening port A than at the opening port B,
the recess 37 is formed at a position close to the opening port B
with respect to the collision wall 34a in a tube axis direction of
the U-bend section 31 as shown in FIG. 13 (B).
[0096] Since the recess 37 is formed adjacent to the collision wall
34a, a cross sectional area of the refrigerant becomes small and
the refrigerant after colliding against the collision wall 34a
becomes difficult to flow. Accordingly, in the case of FIG. 13 (A),
the distribution ratio at the opening port B becomes larger than
that at the opening port A, and in the case of FIG. 13 (B), the
distribution ratio at the opening port A becomes larger than that
at the opening port B.
[0097] Further, the recess 37 is not formed on the collision wall
34a, which faces the straight inflow section 35. Since the recess
37 is formed by using a press or punch, forming the recess 37 on
the collision wall 34a may deform the straight inflow section 35.
Accordingly, the two-way branch pipe 30B can be manufactured in a
stable manner while preventing disadvantage of deformation by not
providing the recess 37 on the collision wall 34a, which faces the
straight inflow section 35.
[0098] As described above, according to Embodiment 4, the number of
capillary tubes 40 can be reduced as similar to Embodiment 1, and a
refrigerant distribution device that can adjust a distribution
ratio of refrigerant can be provided.
[0099] Although the first distribution device 20 is described as a
distributor in the above Embodiments 1 to 4, the invention is not
limited thereto, and the first distribution device 20 may be a
header 70 as shown in FIG. 15. In that case, the same effect can be
obtained.
[0100] The heat exchanger described in the above Embodiments and an
air conditioning apparatus that uses the heat exchanger can achieve
the above effects with any refrigerating machine oil such as
mineral oil, alkylbenzene oil, ester oil, ether oil, and fluorine
oil regardless of whether the refrigerant dissolves in the oil or
not.
[0101] Although Embodiments 1 to 4 are described as separate
Embodiments, combination of Embodiments can be used as appropriate
when Embodiments can be combined. For example, the two-way branch
pipe 30 of Embodiment 2 shown in FIG. 10 can be replaced with the
two-way branch pipe 30A of Embodiment 3 by combining Embodiment 2
and Embodiment 3.
INDUSTRIAL APPLICABILITY
[0102] As an application example, the present invention can be used
for a heat exchanger of a heat pump apparatus that is required to
improve heat exchange efficiency and performance.
* * * * *