U.S. patent application number 13/813675 was filed with the patent office on 2013-05-23 for heat exchanger and refrigeration and air-conditioning apparatus.
This patent application is currently assigned to Mitsubishi Electric Corporation. The applicant listed for this patent is Soshi Ikeda, Hiroaki Nakamune, Mizuo Sakai, Susumu Yoshimura. Invention is credited to Soshi Ikeda, Hiroaki Nakamune, Mizuo Sakai, Susumu Yoshimura.
Application Number | 20130126127 13/813675 |
Document ID | / |
Family ID | 45559200 |
Filed Date | 2013-05-23 |
United States Patent
Application |
20130126127 |
Kind Code |
A1 |
Yoshimura; Susumu ; et
al. |
May 23, 2013 |
HEAT EXCHANGER AND REFRIGERATION AND AIR-CONDITIONING APPARATUS
Abstract
A heat exchanger includes a first flat pipe including plural
through-holes through which a high-temperature fluid flows, a
second flat pipe including plural through-holes through which a
low-temperature fluid flows, a first tubular shape inlet header
connected to one end of the first flat pipe, a first tubular shape
outlet header connected to another end of the first flat pipe, a
second tubular shape inlet header connected to one end of the
second flat pipe, and a second tubular shape outlet header
connected to another end of the second flat pipe. The first and
second flat pipes are stacked with contacting flat surfaces. The
low-temperature fluid flowing into the through-holes in the second
flat pipe from the second inlet header is a fluid in a two-phase
gas-liquid state, and flows into those through-holes in a
substantially horizontal direction or in an upward direction
relative to the substantially horizontal direction.
Inventors: |
Yoshimura; Susumu;
(Chiyoda-ku, JP) ; Nakamune; Hiroaki; (Chiyoda-ku,
JP) ; Sakai; Mizuo; (Chiyoda-ku, JP) ; Ikeda;
Soshi; (Chiyoda-ku, JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yoshimura; Susumu
Nakamune; Hiroaki
Sakai; Mizuo
Ikeda; Soshi |
Chiyoda-ku
Chiyoda-ku
Chiyoda-ku
Chiyoda-ku |
|
JP
JP
JP
JP |
|
|
Assignee: |
Mitsubishi Electric
Corporation
Chiyoda-ku,Tokyo
JP
|
Family ID: |
45559200 |
Appl. No.: |
13/813675 |
Filed: |
August 5, 2011 |
PCT Filed: |
August 5, 2011 |
PCT NO: |
PCT/JP2011/004459 |
371 Date: |
February 1, 2013 |
Current U.S.
Class: |
165/104.19 |
Current CPC
Class: |
F28F 7/02 20130101; F28D
7/0025 20130101; F25B 2400/13 20130101; F25B 2500/01 20130101; F25B
39/00 20130101; F28F 1/025 20130101; F28D 1/02 20130101 |
Class at
Publication: |
165/104.19 |
International
Class: |
F28D 1/02 20060101
F28D001/02; F28D 15/00 20060101 F28D015/00 |
Foreign Application Data
Date |
Code |
Application Number |
Aug 5, 2010 |
JP |
2010-176044 |
Claims
1-9. (canceled)
10. A heat exchanger comprising: a main body in which a plurality
of through-holes are arranged in parallel to each other as a first
passage section and a plurality of through-holes aligned with the
first passage section are arranged in parallel to each other as a
second passage section, the main body being integrally formed with
the first passage section and the second passage section, wherein
the main body is formed with a second inlet header as a hole that
communicates with the plurality of through-holes of the second
passage section, the second inlet header is formed to shift a
position away from the through-holes aligned with the first passage
section relative to a connection position between the second inlet
header and the plurality of through-holes of the second passage
section.
11. A refrigeration and air-conditioning apparatus comprising the
heat exchanger of claim 10.
12. The heat exchanger of claim 10, wherein the second inlet header
has a central axis, and in case of observing in a direction of the
central axis, the central axis is disposed at the position away
from the through-holes aligned with the first passage section
relative to the connection position between the second inlet header
and the through-holes of the second passage section.
13. The heat exchanger of claim 10, wherein the main body includes
a first inlet header and a first outlet header as holes that
communicate with the plurality of through-holes of the first
passage section, and the main body includes a second outlet header
as a hole that communicates with the plurality of through-holes of
the second passage section.
14. The heat exchanger of claim 13, wherein a hole of the first
inlet header, a hole of the second inlet header, a hole of the
first outlet header, and a hole of the second outlet header are
each a shifted position in an extending direction of through-holes
of the first passage section or the second passage section.
15. A method for heat exchange that uses the heat exchanger of
claim 10, comprising: flowing a two-phase gas-liquid fluid into the
second passage section, the two-phase gas-liquid fluid being lower
temperature than a fluid flowed into the first passage section.
16. The method for heat exchange of claim 15, wherein an extending
direction of the plurality of through-holes of the second passage
section is set to a vertical direction, and a direction for the
second inlet header to communicate is set to a horizontal
direction.
17. The method for heat exchange of claim 16, further comprising:
flowing the fluid into the second passage section upward from the
second inlet header.
18. The method for heat exchange of claim 15, wherein an extending
direction of the plurality of through-holes of the second passage
section is set horizontally, and in case of observing in a
central-axis direction of the second inlet header, a direction from
a position of a central-axis of the hole of the second inlet header
to a connection position between the second inlet header and the
through-holes of the first passage section is set upward relative
to a horizontal direction.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger that
exchanges heat between a low-temperature fluid and a
high-temperature fluid so as to transfer the heat from the
high-temperature fluid to the low-temperature fluid. Moreover, the
present invention relates to a refrigeration and air-conditioning
apparatus equipped with the heat exchanger.
BACKGROUND ART
[0002] A heat exchanger in the related art includes a first passage
section having a plurality of through-holes through which a
low-temperature fluid flows, a second passage section having a
plurality of through-holes through which a high-temperature fluid
flows, first headers connected to both ends of the first passage
section, and second headers connected to both ends of the second
passage section. The first passage section and the second passage
section are stacked with surfaces thereof in contact with each
other such that longitudinal directions (i.e., fluid flowing
directions) thereof are parallel to each other. Moreover, at least
one of the high-temperature fluid and the low-temperature fluid is
a fluid in a two-phase gas-liquid state. An inlet header through
which the fluid in the two-phase gas-liquid state flows has an
inner diameter that is smaller than the inner diameter of the other
headers. Thus, the gas and the liquid are made uniform by mixing of
the gas and the liquid within a pipe due to an increase in gas flow
velocity, so that the low-temperature fluid is distributed to the
through-holes with a uniform gas-to-liquid ratio, thereby
maximizing the temperature efficiency of the fluid and achieving
high heat exchanging performance (for example, see Patent
Literature 1).
CITATION LIST
Patent Literature
[0003] Patent Literature 1: Japanese Unexamined Patent Application
Publication No. 2008-101852 (paragraph [0036], FIG. 1)
SUMMARY OF INVENTION
Technical Problem
[0004] A refrigeration and air-conditioning apparatus that uses the
aforementioned heat exchanger in the related art has a refrigerant
circuit in which a compressor, a radiator, flow control means, and
an evaporator are connected by a refrigerant pipe, and a
refrigerant, such as an HFC (hydrofluorocarbon) based refrigerant,
hydrocarbon, or carbon dioxide, circulates through this refrigerant
circuit. In order to increase the efficiency of the refrigeration
and air-conditioning apparatus, it is important to increase the
heat exchanging performance of the heat exchanger.
[0005] However, in the aforementioned heat exchanger in the related
art, when the refrigerant in the two-phase gas-liquid state flows
through the inlet header in a low flow-rate range, the mixing of
the gas and the liquid is insufficient, causing the gas and the
liquid to flow separately from each other. Thus, the ratio of the
gas and the liquid distributed to the through-holes in the passage
section becomes non-uniform. This results in an excess or
insufficient amount of fluid that can effectively exchange heat in
each of the through-holes in the passage section. Therefore, in the
aforementioned heat exchanger in the related art, there is a
problem in that the temperature efficiency significantly decreases,
causing the heat exchanging performance to deteriorate. There is
another problem in that the heat exchanger needs to be increased in
size more than necessary to compensate for the deterioration in the
heat exchanging performance. On the other hand, if the header
diameter is reduced too much in accordance with the low flow-rate
range, when the refrigerant in the two-phase gas-liquid state flows
through the inlet header in a high flow-rate range, a pressure loss
increases, which is a problem in that it leads to an increase in
power used by a driving device that transports the fluid to the
heat exchanger. Accordingly, with the aforementioned heat exchanger
in the related art, it is difficult to make the heat exchanger
operate efficiently while achieving uniform gas-liquid distribution
over a wide operating range.
[0006] The present invention has been made to solve the
aforementioned problems, and an object thereof is to obtain a
compact, high-performance heat exchanger and a compact,
high-performance refrigeration and air-conditioning apparatus.
Solution to Problem
[0007] A heat exchanger according to the present invention includes
a first passage section having a plurality of through-holes through
which a high-temperature fluid flows; a second passage section
having a plurality of through-holes through which a low-temperature
fluid flows; a first inlet header having a tubular shape and
connected to one end of the first passage section; a first outlet
header having a tubular shape and connected to other end of the
first passage section; a second inlet header having a tubular shape
and connected to one end of the second passage section; and a
second outlet header having a tubular shape and connected to other
end of the second passage section. The first passage section and
the second passage section are disposed in a heat exchangeable
manner via a partition wall provided therebetween. At least one of
the high-temperature fluid flowing into the through-holes in the
first passage section from the first inlet header and the
low-temperature fluid flowing into the through-holes in the second
passage section from the second inlet header is a fluid in a
two-phase gas-liquid state. A direction in which the fluid in the
two-phase gas-liquid state flows into the passage section from the
inlet header is a substantially horizontal direction or an upward
direction relative to the substantially horizontal direction.
[0008] A refrigeration and air-conditioning apparatus according to
the present invention is equipped with the heat exchanger according
to the present invention.
Advantageous Effects of Invention
[0009] According to the present invention, a compact,
high-performance heat exchanger can be provided. Furthermore,
according to the present invention, a compact, high-performance
refrigeration and air-conditioning apparatus can be provided.
BRIEF DESCRIPTION OF DRAWINGS
[0010] FIG. 1 illustrates a heat exchanger according to Embodiment
1 of the present invention.
[0011] FIG. 2 is a vertical sectional view illustrating another
example of second flat pipes according to Embodiment 1 of the
present invention.
[0012] FIG. 3 illustrates the heat transfer characteristics of the
heat exchanger according to Embodiment 1 of the present
invention.
[0013] FIG. 4 illustrates another example of the heat transfer
characteristics of the heat exchanger according to Embodiment 1 of
the present invention.
[0014] FIG. 5 illustrates another example of the heat transfer
characteristics of the heat exchanger according to Embodiment 1 of
the present invention.
[0015] FIG. 6 includes side views illustrating examples of a heat
exchanger according to Embodiment 2 of the present invention.
[0016] FIG. 7 is a refrigerant circuit diagram illustrating an
example of a refrigeration and air-conditioning apparatus according
to Embodiment 3 of the present invention.
[0017] FIG. 8 is a refrigerant circuit diagram illustrating another
example of the refrigeration and air-conditioning apparatus
according to Embodiment 3 of the present invention.
[0018] FIG. 9 is a refrigerant circuit diagram illustrating another
example of the refrigeration and air-conditioning apparatus
according to Embodiment 3 of the present invention.
[0019] FIG. 10 includes structural diagrams of a heat exchanger
according to Embodiment 4 of the present invention.
[0020] FIG. 11 includes structural diagrams illustrating another
example of the heat exchanger according to Embodiment 4 of the
present invention.
DESCRIPTION OF EMBODIMENTS
Embodiment 1
[0021] FIG. 1 illustrates a heat exchanger according to Embodiment
1 of the present invention, and includes FIG. 1(a) showing a
perspective view, FIG. 1(b) showing a side view, and FIG. 1(c)
showing a sectional view of the vicinity of a connection area
between a second inlet header and each second flat pipe. FH shown
in FIG. 1(a) denotes the flow of a high-temperature fluid, and FC
shown in FIG. 1(a) denotes the flow of a low-temperature fluid.
Embodiment 1 is directed to a case where the low-temperature fluid
in a two-phase gas-liquid state flows into the second header. In
the following drawings, components given the same reference
numerals or characters indicate the same components or equivalent
components, and this commonly applies throughout the entire
specification.
[0022] In Embodiment 1, a substantially-horizontal inflow segment
2a is provided at an end of each second flat pipe 2 shown in FIG. 1
on the basis of information obtained from tests shown in FIGS. 3 to
5, that is, the ranges of position angles .alpha., .beta., and
.gamma., to be described later, providing excellent heat transfer
characteristics, whereby a heat exchanger 10 having excellent heat
transfer characteristics is achieved. Specifically, in FIG. 1, the
second flat pipes 2 are connected to a second inlet header 5 with a
position angle .alpha. of 90.degree..
[0023] First flat pipes 1 each have a plurality of through-holes
extending in the longitudinal direction (i.e., the left-right
direction in FIG. 1(b)) and through which the high-temperature
fluid flows. The through-holes are arranged parallel to each other
in the width direction of the first flat pipe 1 (i.e., a direction
orthogonal to the plane of FIG. 1(b)). The second flat pipes 2 each
have a plurality of through-holes 21 extending in the longitudinal
direction (i.e., the left-right direction in FIG. 1(b)) and through
which the low-temperature fluid flows. The through-holes 21 are
arranged parallel to each other in the width direction of the
second flat pipe 2 (i.e., the direction orthogonal to the plane of
FIG. 1(b)). The first flat pipes 1 and the second flat pipes 2 are
stacked such that flat surfaces of the first flat pipes 1 and flat
surfaces of heat exchanging segments 2c of the second flat pipes 2
are in contact with each other. Furthermore, the first flat pipes 1
and the second flat pipes 2 are stacked such that the flowing
directions of the fluids flowing through the flat pipes 1 and 2 are
parallel to each other. The first flat pipes 1 and the second flat
pipes 2 are joined to each other by, for example, soldering or
bonding. For example, if the first flat pipes 1 and the second flat
pipes 2 are both composed of aluminum or an aluminum alloy, the
solder or flux used for soldering is composed of
aluminum/silicon-based material, fluoride-based material, or the
like. Furthermore, for example, if the group of first flat pipes 1
or second flat pipes 2 are composed of aluminum or an aluminum
alloy while the other group of first flat pipes 1 or second flat
pipes 2 are composed of copper, the solder or flux used for
soldering is composed of zinc/aluminum-based material,
aluminum/cesium/fluoride-based material or the like. With regard to
a combination of solder and flux, a combination in which the
melting point of the former is close to the activation temperature
of the latter is preferable since the solderability improves due
to, for example, better flowability of the solder.
[0024] One longitudinal end of each first flat pipe 1 is connected
to a side surface of a first inlet header 3 having a tubular shape,
while the other end is connected to a side surface of a first
outlet header 4 having a tubular shape. In other words, the
through-holes formed in the first flat pipes 1 form parallel
passages through which the high-temperature fluid flows. The inflow
segment 2a serving as one longitudinal end of each second flat pipe
2 is connected to a side surface of the second inlet header 5
having a tubular shape. An outflow segment 2d serving as the other
longitudinal end of each second flat pipe 2 is connected to a side
surface of a second outlet header 6 having a tubular shape. The
inflow segment 2a and the outflow segment 2d are connected to the
heat exchanging segment 2c via bent segments 2b. In other words,
the through-holes 21 formed in the second flat pipes 2 form
parallel passages through which the low-temperature fluid
flows.
[0025] The first inlet header 3, the first outlet header 4, the
second inlet header 5, and the second outlet header 6 are disposed
such that axial directions thereof are parallel to the flat
surfaces of the flat pipes 1 and 2 (specifically, the
parallel-arranged direction of the through-holes formed in the flat
pipes 1 and 2).
[0026] Furthermore, the inflow segments 2a of the second flat pipes
2, through which the low-temperature fluid in the two-phase
gas-liquid state flows, connected to the second inlet header 5 are
substantially horizontal. Specifically, the passages (in other
words, the through-holes 21 in the inflow segments 2a) for the
low-temperature fluid in the two-phase gas-liquid state flowing
into the second flat pipes 2 from the second inlet header 5 are
substantially horizontal.
[0027] The first flat pipes 1 correspond to "first passage section"
according to the present invention, and the second flat pipes 2
correspond to "second passage section" according to the present
invention.
[0028] The high-temperature fluid flows through the first inlet
header 3, the first flat pipes 1, and the first outlet header 4 in
that order, the low-temperature fluid flows through the second
inlet header 5, the second flat pipes 2, and the second outlet
header 6 in that order, and the two fluids exchange heat via
contact sections between the first flat pipes 1 and the second flat
pipes 2 (more specifically, the heat exchanging segments 2c). In
other words, the high-temperature fluid flowing through the
through-holes in the first flat pipes 1 and the low-temperature
fluid flowing through the through-holes in the second flat pipes 2
exchange heat via outer hulls, serving as partition walls between
the through-holes, of the first flat pipes 1 and the second flat
pipes 2.
[0029] Although the heat exchanger 10 is constituted of several
first flat pipes 1 and several second flat pipes 2 in Embodiment 1,
the number of flat pipes 1 and the number of flat pipes 2 are not
limited to the numbers in Embodiment 1. The parallel passages may
be formed by alternately arranging one first flat pipe 1 and one
second flat pipe 2 along a flat plane. Furthermore, although the
first flat pipes 1 and the second flat pipes 2 in Embodiment 1 are
disposed in contact with each other such that the flowing
directions of the fluids flowing therethrough are parallel to each
other, the flat pipes may alternatively be disposed in contact with
each other such that the flowing directions are orthogonal to each
other. As a further alternative, the first flat pipes 1 and the
second flat pipes 2 may be stacked while folding the first flat
pipes 1 and the second flat pipes 2. Furthermore, although the end
of the inflow segment 2a of each second flat pipe 2 is
substantially aligned with the inner surface of the second inlet
header 5 in FIG. 1(c), the end of the inflow segment 2a of each
second flat pipe 2 may alternatively protrude into the second inlet
header 5.
[0030] In the heat exchanger 10 according to Embodiment 1, the ends
of the second flat pipes 2, through which the two-phase gas-liquid
fluid flows, connected to the second inlet header 5 are
substantially horizontal. In other words, the outflowing direction
of the two-phase gas-liquid fluid flowing out from the second inlet
header 5 toward the through-holes 21 (in other words, the inflowing
direction of the two-phase gas-liquid fluid flowing into the
through-holes 21) is substantially horizontal. More specifically,
in Embodiment 1, even when the refrigerant flow velocity within the
second inlet header 5 decreases to cause the gas and the liquid to
flow separately through the upper side and the lower side therein,
the liquid accumulates from the bottom of the second inlet header 5
to near the inflow segments of the second flat pipes 2 so that a
gas-liquid interface is formed exactly near the inflow segments of
the second flat pipes 2, whereby favorable gas-liquid distribution
is achieved. In other words, for example, if the refrigerant flows
vertically downward from the horizontally-disposed second inlet
header 5 toward the second flat pipes 2, the gas-liquid
distribution would deteriorate since the liquid alone tends to
selectively flow out toward the second flat pipes 2 located at the
upstream side before a liquid surface is formed within the second
inlet header 5. In contrast, this does not occur in the heat
exchanger 10 according to Embodiment 1 because the ends of the
second flat pipes 2 connected to the second inlet header 5 are
substantially horizontal. Therefore, the low-temperature fluid can
be distributed to the through-holes 21 in the second flat pipes 2
with a uniform gas-to-liquid ratio so that the temperature
efficiency of the fluid can be maximized and the pressure loss can
be minimized, thereby allowing for improved heat exchanging
performance of the heat exchanger 10. Consequently, with the heat
exchanger 10 according to Embodiment 1, a compact, high-performance
heat exchanger can be obtained.
[0031] With regard to the ends of the flat pipes connected to the
remaining headers 3, 4, and 6, the ends do not particularly need to
be horizontal unless a two-phase gas-liquid fluid flows
therethrough.
[0032] Furthermore, although the inflow segments 2a are formed by
bending the second flat pipes 2 outside the second inlet header 5
in Embodiment 1, the inflow segments 2a may alternatively be formed
by bending the second flat pipes 2 inside the second inlet header 5
to an extent that the gas-liquid flow within the second inlet
header 5 is not disturbed, as shown in FIG. 2.
[0033] In the heat exchanger 10 according to Embodiment 1, the
inflow segments 2a of the second flat pipes 2 connected to the
second inlet header 5 are maintained in a substantially horizontal
state even if the heat exchanger 10 is positionally inverted.
Therefore, the gas-liquid distribution does not deteriorate.
Consequently, the heat exchanger 10 according to Embodiment 1 is
advantageous in that the degree of freedom in terms of installation
and the degree of freedom in terms of connection and routing of
pipes are increased.
[0034] Generally, the distribution characteristics of the two-phase
gas-liquid fluid toward the through-holes in the flat pipes change
significantly depending on the outflowing direction of the fluid
flowing out from the header toward the through-holes (in other
words, the inflowing direction of the fluid flowing into the
through-holes). Therefore, an effect that this direction has on the
heat transfer characteristics (i.e., the distribution
characteristics of the two-phase gas-liquid fluid) in the heat
exchanger 10 is examined by performing tests (FIGS. 3 to 5). In the
tests shown in FIGS. 3 to 5, hot water is made to flow as the
high-temperature fluid through the first flat pipes 1, and a
low-temperature fluorocarbon refrigerant in a two-phase gas-liquid
state is made to flow as the low-temperature fluid through the
second flat pipes 2. Then, heat transfer characteristics KA (W/K)
of the heat exchanger 10 are measured by using the inlet and outlet
temperatures of each fluid and mathematical expressions 1 and
2.
KA = M h Cp h ( T hi - T ho ) 3600 [ LMTD ] [ Mathematical
Expression 1 ] [ LMTD ] = ( T hi - T co ) - ( T ho - T ci ) ln ( T
hi - T co ) ( T ho - T ci ) [ Mathematical Expression 2 ]
##EQU00001##
[0035] In this case, M.sub.h denotes a mass flow rate (kg/h) of the
high-temperature fluid, Cp.sub.h denotes isobaric specific heat
(J/kgK) of the high-temperature fluid, T.sub.hi denotes an inlet
temperature of the high-temperature fluid, T.sub.ho denotes an
outlet temperature of the high-temperature fluid, T.sub.co denotes
an outlet temperature of the low-temperature fluid, and T.sub.ci
denotes an inlet temperature of the low-temperature fluid.
[0036] In the tests shown in FIGS. 3 to 5, the configuration of the
heat exchanger 10 is set as follows.
[0037] The second inlet header 5 has an inner diameter D of 6 mm.
The through-holes formed in the first flat pipes 1 are rectangular
holes with about 1 mm sides, and a total of 60 through-holes are
formed in each first flat pipe 1. Furthermore, these through-holes
are arranged in the width direction of the first flat pipe 1. The
through-holes 21 formed in the second flat pipes 2 are also
rectangular holes with about 1 mm sides, and a total of 60
through-holes 21 are formed in each second flat pipe 2.
Furthermore, these through-holes 21 are arranged in the width
direction of the second flat pipe 2.
[0038] The protruding length of the ends of each first flat pipe 1
from the inner surfaces of the headers is 2 mm.
[0039] In the tests shown in FIGS. 3 to 5, the heat transfer
characteristics KA (W/K) are measured under the following
conditions.
[0040] The mass flow rate M.sub.h of the high-temperature fluid is
600 kg/h. A mass flow rate M.sub.c of the low-temperature fluid
ranges between 80 kg/h and 100 kg/h. A ratio of the mass flow rate
of the gas to the overall mass flow rate of the gas and the liquid
in the low-temperature fluid (i.e., quality X) is adjusted between
0.1 and 0.2. This range of the quality X is a generally used range
for the inlet quality in the heat exchanger 10 used in a common
refrigeration and air-conditioning apparatus.
[0041] The triangles, squares, and circles shown in FIG. 3(c), FIG.
4(c), and FIG. 5(c) express the heat transfer characteristics under
the following conditions. The squares express the heat transfer
characteristics when the mass flow rate M.sub.c of the
low-temperature fluid is 80 kg/h. The triangles express the heat
transfer characteristics when the mass flow rate M.sub.c of the
low-temperature fluid is 90 kg/h. The circles express the heat
transfer characteristics when the mass flow rate M.sub.c of the
low-temperature fluid is 100 kg/h.
[0042] In FIGS. 3 to 5, when the second inlet header 5 is in a near
horizontal state, the refrigerant within the second inlet header 5
tends to flow such that the gas and the liquid flow separately
through the upper side and the lower side therein due to mass
velocity. When the second inlet header 5 is in a near vertical
state, the refrigerant within the second inlet header 5 tends to
flow such that the gas and the liquid flow annularly due to mass
velocity. For example, a difference in properties between when the
header is in a horizontal state and when the header is in a
vertical state begins to occur near a position angle .gamma. or
.beta. of 45.degree..
[0043] FIG. 3 illustrates the heat transfer characteristics
obtained when the second inlet header 5 is horizontally disposed
and the position angle .alpha., which corresponds to the outflowing
direction of the low-temperature fluid in the two-phase gas-liquid
state flowing out toward the through-holes 21 in the second flat
pipes 2 (in other words, the inflowing direction of the
low-temperature fluid flowing into the through-holes 21), is
changed. Specifically, FIG. 3(a) is a diagram for explaining the
position angle .alpha.. FIG. 3(b) illustrates the positions of the
heat exchanger 10 at main position angles .alpha.. FIG. 3(c) shows
a test result and illustrates the relationship between the position
angle a and the heat transfer characteristics (relative value). The
heat transfer characteristics (relative value) of the heat
exchanger 10 indicated on the ordinate axis in FIG. 3(c) are
expressed by relative values, with 1 as the heat transfer
characteristics obtained under a condition in which the
low-temperature fluid is distributed to the through-holes 21 in the
second flat pipes 2 with a uniform gas-to-liquid ratio.
[0044] Unlike the heat exchanger 10 shown in FIG. 1, the ends of
the second flat pipes 2 shown in FIG. 3 each have one folded
section. In other words, in each of the second flat pipes 2 shown
in FIG. 3, the inflow segment 2a and the outflow segment 2d are
directly connected to the heat exchanging segment 2c (without the
intervention of the bent segments 2b). Furthermore, when the
position angle .alpha.=0.degree., the low-temperature fluid (in the
two-phase gas-liquid state) flows out toward the through-holes 21
in the second flat pipes 2 in a vertically upward direction. When
0.degree.<position angle .alpha.<90.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows out
toward the through-holes 21 in the second flat pipes 2 upward
relative to the horizontal direction. When the position angle
.alpha.=90.degree., the low-temperature fluid (in the two-phase
gas-liquid state) flows out toward the through-holes 21 in the
second flat pipes 2 in the horizontal direction. When
90.degree.<position angle .alpha.<180.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows out
toward the through-holes 21 in the second flat pipes 2 downward
relative to the horizontal direction. When the position angle
.alpha.=180.degree., the low-temperature fluid (in the two-phase
gas-liquid state) flows out toward the through-holes 21 in the
second flat pipes 2 in a vertically downward direction.
[0045] As shown in FIG. 3(c), it is confirmed that, when
-110.degree.<position angle .alpha.<110.degree. (more
preferably, 80.degree.<position angle .alpha.<100.degree. or
-80.degree.<position angle .alpha.<-100.degree.), the heat
transfer characteristics can be maintained at a high level. In
particular, it is confirmed that, when the position angle .alpha.
is close to 90.degree. (85.degree.<position angle
.alpha.<95.degree. or -85.degree.<position angle
.alpha.<-95.degree.), the heat transfer characteristics are at
the maximum level. It is also confirmed that, when the position
angle .alpha. is smaller than or equal to 110.degree., the heat
transfer characteristics decrease sharply. In other words, it is
confirmed from this result that, when -110.degree.<position
angle .alpha.<110.degree., the gas-to-liquid ratio of the
low-temperature fluid distributed to the through-holes 21 is
substantially made uniform. Furthermore, it is confirmed that, by
setting the position angle .alpha. to substantially -90.degree. or
substantially 90.degree., the gas-to-liquid ratio of the
low-temperature fluid distributed to the through-holes 21 can be
made more uniform. Accordingly, by setting the position angle
.alpha. to substantially -90.degree. or substantially 90.degree.,
even when the flow velocity within the second inlet header 5
decreases to cause the gas and the liquid to flow separately
through the upper side and the lower side therein, the inflow
segments extending from the second inlet header 5 to the second
flat pipes 2 are prevented from being constantly filled with the
liquid, thereby preventing deterioration in the gas-liquid
distribution caused by the liquid alone flowing out selectively to
the second flat pipes 2 located at the upstream side. When the
position angle .alpha. is close to 0.degree., the liquid tends to
flow into the second flat pipes 2 located toward the far side as
viewed from the inlet side of the second inlet header 5 due to, for
example, inertia of the liquid. However, since the flow is
suppressed by gravity acting on the liquid, deterioration in the
distribution is minimized to a certain extent.
[0046] FIG. 4 illustrates the heat transfer characteristics
obtained when the outflowing direction of the low-temperature fluid
in the two-phase gas-liquid state flowing out toward the
through-holes 21 in the second flat pipes 2 is set to be horizontal
and the position angle .gamma. of the second inlet header 5 is
changed. Specifically, FIG. 4(a) is a diagram for explaining the
position angle .gamma.. FIG. 4(b) illustrates the positions of the
heat exchanger 10 at main position angles .gamma.. FIG. 4(c) shows
a test result and illustrates the relationship between the position
angle .gamma. and the heat transfer characteristics (relative
value). The heat transfer characteristics (relative value) of the
heat exchanger 10 indicated on the ordinate axis in FIG. 4(c) are
expressed by relative values, with 1 as the heat transfer
characteristics obtained under a condition in which the
low-temperature fluid is distributed to the through-holes 21 in the
second flat pipes 2 with a uniform gas-to-liquid ratio.
[0047] Unlike the heat exchanger 10 shown in FIG. 1, the ends of
the second flat pipes 2 shown in FIG. 4 do not have folded
sections. In other words, in each of the second flat pipes 2 shown
in FIG. 4, the inflow segment 2a, the outflow segment 2d, and the
heat exchanging segment 2c are parallel to each other. Furthermore,
when the position angle .gamma.=0.degree., the low-temperature
fluid (in the two-phase gas-liquid state) flows into the second
inlet header 5 in a horizontal direction. When
0.degree.<position angle .gamma.<90.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows
into the second inlet header 5 downward relative to the horizontal
direction. When the position angle .gamma.=90.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows
into the second inlet header 5 in the vertically downward
direction. When -90.degree.<position angle .gamma.<0.degree.,
the low-temperature fluid (in the two-phase gas-liquid state) flows
into the second inlet header 5 upward relative to the horizontal
direction. When the position angle .gamma.=-90.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows
into the second inlet header 5 in the vertically upward
direction.
[0048] As shown in FIG. 4(c), it is confirmed that the heat
transfer characteristics of the heat exchanger 10 tend to be
slightly higher when the second inlet header 5 is set in a vertical
position, but the effect of the position angle .gamma. against the
position of the second inlet header 5 is relatively small.
[0049] FIG. 5 illustrates the heat transfer characteristics
obtained when both the position of the second inlet header 5 and
the outflowing direction of the low-temperature fluid in the
two-phase gas-liquid state flowing out toward the through-holes 21
in the second flat pipes 2 are changed. Specifically, FIG. 5(a) is
a diagram for explaining the position angle .beta.. FIG. 5(b)
illustrates the positions of the heat exchanger 10 at main position
angles .beta.. FIG. 5(c) shows a test result and illustrates the
relationship between the position angle .beta. and the heat
transfer characteristics (relative value). The heat transfer
characteristics (relative value) of the heat exchanger 10 indicated
on the ordinate axis in FIG. 5(c) are expressed by relative values,
with 1 as the heat transfer characteristics obtained under a
condition in which the low-temperature fluid is distributed to the
through-holes 21 in the second flat pipes 2 with a uniform
gas-to-liquid ratio.
[0050] Unlike the heat exchanger 10 shown in FIG. 1, the ends of
the second flat pipes 2 shown in FIG. 5 each have one folded
section. In other words, in each of the second flat pipes 2 shown
in FIG. 5, the inflow segment 2a and the outflow segment 2d are
directly connected to the heat exchanging segment 2c (without the
intervention of the bent segments 2b).
[0051] When the position angle .beta.=0.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows out
toward the through-holes 21 in the second flat pipes 2 in the
horizontal direction, and the low-temperature fluid (in the
two-phase gas-liquid state) flows into the second inlet header 5 in
the vertically downward direction. When 0.degree.<position angle
.beta.<90.degree., the low-temperature fluid (in the two-phase
gas-liquid state) flows out toward the through-holes 21 in the
second flat pipes 2 upward relative to the horizontal direction,
and the low-temperature fluid (in the two-phase gas-liquid state)
flows into the second inlet header 5 downward relative to the
horizontal direction. When the position angle .beta.=90.degree.,
the low-temperature fluid (in the two-phase gas-liquid state) flows
out toward the through-holes 21 in the second flat pipes 2 in the
vertically upward direction, and the low-temperature fluid (in the
two-phase gas-liquid state) flows into the second inlet header 5 in
the horizontal direction. When 90.degree.<position angle
.beta.<180.degree., the low-temperature fluid (in the two-phase
gas-liquid state) flows out toward the through-holes 21 in the
second flat pipes 2 upward relative to the horizontal direction,
and the low-temperature fluid (in the two-phase gas-liquid state)
flows into the second inlet header 5 upward relative to the
horizontal direction. When the position angle .beta.=180.degree.,
the low-temperature fluid (in the two-phase gas-liquid state) flows
out toward the through-holes 21 in the second flat pipes 2 in the
horizontal direction, and the low-temperature fluid (in the
two-phase gas-liquid state) flows into the second inlet header 5 in
the vertically upward direction.
[0052] When -90.degree.<position angle .beta.<0.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows out
toward the through-holes 21 in the second flat pipes 2 downward
relative to the horizontal direction, and the low-temperature fluid
(in the two-phase gas-liquid state) flows into the second inlet
header 5 downward relative to the horizontal direction. When the
position angle .beta.=-90.degree., the low-temperature fluid (in
the two-phase gas-liquid state) flows out toward the through-holes
21 in the second flat pipes 2 in the vertically downward direction,
and the low-temperature fluid (in the two-phase gas-liquid state)
flows into the second inlet header 5 in the horizontal direction.
When -180.degree.<position angle .beta.<-90.degree., the
low-temperature fluid (in the two-phase gas-liquid state) flows out
toward the through-holes 21 in the second flat pipes 2 downward
relative to the horizontal direction, and the low-temperature fluid
(in the two-phase gas-liquid state) flows into the second inlet
header 5 downward relative to the horizontal direction. When the
position angle .beta.=-180.degree., the low-temperature fluid (in
the two-phase gas-liquid state) flows out toward the through-holes
21 in the second flat pipes 2 in the horizontal direction, and the
low-temperature fluid (in the two-phase gas-liquid state) flows
into the second inlet header 5 in the vertically downward
direction.
[0053] As shown in FIG. 5(c), it is confirmed that, when
0.degree..ltoreq.position angle .beta..ltoreq.180.degree., the heat
transfer characteristics can be maintained at a high level. In
particular, it is confirmed that, when the position angle .beta. is
close to 90.degree. or close to 180.degree., the heat transfer
characteristics are at the maximum level. It is also confirmed
that, when the position angle .beta. is smaller than 0.degree., the
heat transfer characteristics decrease sharply. In other words, it
is confirmed from this result that, when 0.degree..ltoreq.position
angle .beta..ltoreq.180.degree., the gas-to-liquid ratio of the
low-temperature fluid distributed to the through-holes 21 is
substantially made uniform. Furthermore, it is confirmed that, by
setting the position angle .beta. close to 90.degree. or close to
180.degree., the gas-to-liquid ratio of the low-temperature fluid
distributed to the through-holes 21 can be made more uniform.
(Advantages)
[0054] Accordingly, in the heat exchanger 10 according to
Embodiment 1, at least one of the high-temperature fluid flowing
into the through-holes in the first flat pipes 1 from the first
inlet header 3 and the low-temperature fluid flowing into the
through-holes 21 in the second flat pipes 2 from the second inlet
header 4 is a fluid in a two-phase gas-liquid state. The two-phase
gas-liquid fluid flows into the flat pipes from the inlet header in
a substantially horizontal direction or in an upward direction
relative to the substantially horizontal direction. Therefore, even
when the flow velocity within the second inlet header 5 decreases
to cause the gas and the liquid to flow separately through the
upper side and the lower side therein, the inflow segments
extending from the second inlet header 5 to the second flat pipes 2
are prevented from being constantly filled with the liquid, thereby
preventing deterioration in the gas-liquid distribution caused by
the liquid alone flowing out selectively to the second flat pipes 2
located at the upstream side. Therefore, the two-phase gas-liquid
fluid can be distributed to the through-holes with a uniform
gas-to-liquid ratio so that the temperature efficiency of the fluid
can be maximized and the pressure loss can be minimized. In other
words, the heat exchanging performance of the heat exchanger 10 can
be improved.
[0055] Consequently, with the heat exchanger 10 according to
Embodiment 1, a compact, high-performance heat exchanger can be
obtained.
[0056] The description of Embodiment 1 is directed to a case where
the low-temperature fluid flowing through the second inlet header 5
turns into a two-phase gas-liquid state. If the high-temperature
fluid flowing through the first inlet header 3 turns into a
two-phase gas-liquid state, similar advantages can be achieved by
making the high-temperature fluid flow into the through-holes in
the first flat pipes 1 from the first inlet header 3 in a
substantially horizontal direction.
Embodiment 2
[0057] The configuration of the heat exchanger 10 according to
Embodiment 1 is merely an example; for example, the heat exchanger
10 may be configured as follows. The following description will
mainly be focused on the differences from the heat exchanger 10
according to Embodiment 1.
[0058] FIG. 6 includes side views illustrating examples of a heat
exchanger according to Embodiment 2 of the present invention.
[0059] In a heat exchanger 10 shown in FIG. 6(a), the bent segments
2b of each second flat pipe 2 are substantially U-shaped in cross
section. In other words, the bent segment 2b that connects the
inflow segment 2a and the heat exchanging segment 2c of the second
flat pipe 2 is disposed so as to overpass the first outlet header 4
through which the high-temperature fluid flows. Moreover, the bent
segment 2b that connects the heat exchanging segment 2c and the
outflow segment 2d of the second flat pipe 2 is disposed so as to
overpass the first inlet header 3 through which the
high-temperature fluid flows.
[0060] In addition to achieving the advantages of Embodiment 1, the
heat exchanger 10 having such a configuration achieves compactness
since the height of the flat pipes 1 and 2 is reduced in the
stacked direction thereof.
[0061] In each of the second flat pipes 2 in a heat exchanger 10
shown in FIG. 6(b), the end thereof at the second inlet header 5
side and the end thereof at the second outlet header 6 side are
bent in opposite directions. Moreover, each first flat pipe 1 has
an inflow segment 1a, a heat exchanging segment 1c, an outflow
segment 1d, and bent segments 1b. The inflow segment 1a is
connected to the first inlet header 3 and has a substantially
horizontal passage. The outflow segment 1d is connected to the
first outlet header 4 and has a substantially horizontal passage.
The heat exchanging segment 1c and the heat exchanging segment 2c
of the second flat pipe 2 are stacked such that flat surfaces
thereof are in contact with each other. The bent segments 1b
connect between the inflow segment 1a and the heat exchanging
segment 1c, as well as between the heat exchanging segment 1c and
the outflow segment 1d. The end of each first flat pipe 1 at the
first inlet header 3 side is bent in the same direction as the end
of each second flat pipe 2 at the second outlet header 6 side. The
end of each first flat pipe 1 at the first outlet header 4 side is
bent in the same direction as the end of each second flat pipe 2 at
the second inlet header 5 side.
[0062] In addition to achieving the advantages of Embodiment 1, the
heat exchanger 10 having such a configuration is advantageous in
that the installation space can be made compact in the height
direction when a plurality of heat exchangers 10 are installed. In
other words, when a plurality of heat exchangers 10 are installed
by stacking them in the stacked direction of the flat pipes 1 and 2
for increasing the heat exchanging capability, gaps between the
heat exchangers 10 in the height direction can be reduced while
interference between the headers 3, 4, 5, and 6 is prevented.
[0063] In a heat exchanger 10 shown in FIG. 6(c), the second flat
pipes are provided above the first flat pipes 1 and also below the
first flat pipes 1. Second flat pipes 2A disposed above the first
flat pipes 1 each have an inflow segment 2Aa, a heat exchanging
segment 2Ac, an outflow segment 2Ad, and bent segments 2Ab. The
inflow segment 2Aa is connected to a second inlet header 5A and has
a substantially horizontal passage. The outflow segment 2Ad is
connected to a second outlet header 6A and has a substantially
horizontal passage. The heat exchanging segment 2Ac and the
corresponding first flat pipe 1 are stacked such that flat surfaces
thereof are in contact with each other. The bent segments 2Ab
connect between the inflow segment 2Aa and the heat exchanging
segment 2Ac, as well as between the heat exchanging segment 2Ac and
the outflow segment 2Ad. The ends of each second flat pipe 2A are
bent so as to extend upon the first inlet header 3 and the first
outlet header 4.
[0064] Second flat pipes 2B disposed below the first flat pipes 1
each have an inflow segment 2Ba, a heat exchanging segment 2Bc, an
outflow segment 2Bd, and bent segments 2Bb. The inflow segment 2Ba
is connected to a second inlet header 5B and has a substantially
horizontal passage. The outflow segment 2Bd is connected to a
second outlet header 6B and has a substantially horizontal passage.
The heat exchanging segment 2Bc and the corresponding first flat
pipe 1 are stacked such that flat surfaces thereof are in contact
with each other. The bent segments 2Bb connect between the inflow
segment 2Ba and the heat exchanging segment 2Bc, as well as between
the heat exchanging segment 2Bc and the outflow segment 2Bd. The
ends of each second flat pipe 2B are bent so as to extend under the
first inlet header 3 and the first outlet header 4.
[0065] When increasing the heat exchanging capability, optimizing
the heat transfer and flow characteristics of the second flat pipes
2 or the like, there is a case where two second flat pipes 2A and
2B are disposed for each first flat pipe 1. In the heat exchanger
10 having such a configuration, the low-temperature fluid in the
two-phase gas-liquid state is made to flow out toward the
through-holes 21 in the second flat pipes 2A in a substantially
horizontal direction. Furthermore, in the heat exchanger 10 having
such a configuration, the low-temperature fluid in the two-phase
gas-liquid state is made to flow out toward the through-holes 21 in
the second flat pipes 2B in a substantially horizontal direction.
Therefore, similar to Embodiment 1, the gas-to-liquid ratio of the
low-temperature fluid distributed to the through-holes 21 can be
made uniform, whereby a compact, high-performance heat exchanger 10
can be obtained.
Embodiment 3
[0066] The heat exchanger 10 according to each of Embodiment 1 and
Embodiment 2 is installed in, for example, a refrigeration and
air-conditioning apparatus, such as an air-conditioning apparatus,
a hot-water storage apparatus, or a refrigeration apparatus. An
example of a refrigeration and air-conditioning apparatus equipped
with the heat exchanger 10 according to Embodiment 1 or Embodiment
2 will be described below.
[0067] FIG. 7 is a refrigerant circuit diagram illustrating an
example of a refrigeration and air-conditioning apparatus according
to Embodiment 3 of the present invention.
[0068] The refrigeration and air-conditioning apparatus shown in
FIG. 7 has a first refrigerant circuit in which a first compressor
30, a first radiator 31, a first pressure reducing device 32, and a
first cooling unit 33 are connected in that order with pipes. The
first refrigerant circuit makes a first refrigerant serving as a
high-temperature fluid circulate therethrough and operates based on
a vapor compression refrigeration cycle. The heat exchanger 10 is
disposed between the first radiator 31 and the first pressure
reducing device 32 in the first refrigerant circuit. The first
inlet header 3 of the heat exchanger 10 is connected to the first
radiator 31, and the first outlet header 4 is connected to the
first pressure reducing device 32.
[0069] The refrigeration and air-conditioning apparatus also has a
second refrigerant circuit in which the heat exchanger 10, a second
compressor 40, a second radiator 41, and a second pressure reducing
device 42 are connected in that order with pipes. The second outlet
header 6 of the heat exchanger 10 is connected to the second
compressor 40, and the second inlet header 5 is connected to the
second pressure reducing device 42. The second refrigerant circuit
makes a second refrigerant serving as a low-temperature fluid
circulate therethrough and operates based on a vapor compression
refrigeration cycle. The first refrigerant and the second
refrigerant used are a refrigerant such as carbon dioxide, an
HFC-based refrigerant, an HC-based refrigerant, an HFO-based
refrigerant, and ammonia. In Embodiment 3, carbon dioxide is used
as the first refrigerant.
[0070] The first refrigerant is compressed by the first compressor
30 and is discharged therefrom as a high-temperature high-pressure
supercritical fluid. The first refrigerant having become a
high-temperature high-pressure supercritical fluid is transported
to the first radiator 31 and is decreased in temperature by
exchanging heat with air or the like at the first radiator 31,
thereby becoming a high-pressure supercritical fluid. The first
refrigerant having become a high-pressure supercritical fluid is
decreased in temperature by being cooled by the heat exchanger 10,
flows into the first pressure reducing device 32 where the first
refrigerant is decompressed so as to change into a low-temperature
low-pressure two-phase gas-liquid state, and is then transported to
the first cooling unit 33. The first refrigerant in the
low-temperature low-pressure two-phase gas-liquid state evaporates
by exchanging heat with air or the like at the first cooling unit
33 and then returns to the first compressor 30.
[0071] On the other hand, the second refrigerant is compressed by
the second compressor 40 and is discharged therefrom as
high-temperature high-pressure vapor. The second refrigerant having
becoming high-temperature high-pressure vapor is transported to the
second radiator 41 and is decreased in temperature by exchanging
heat with air or the like at the second radiator 41, thereby
becoming a high-pressure liquid. The second refrigerant having
become a high-pressure liquid is decompressed by the second
pressure reducing device 42 so as to change into a low-temperature
two-phase gas-liquid state, and is transported to the heat
exchanger 10. The second refrigerant in the low-temperature
two-phase gas-liquid state becomes vapor by being heated at the
heat exchanger 10 and then returns to the second compressor 40.
[0072] In the refrigeration and air-conditioning apparatus having
such a configuration, a large degree of subcooling for the
refrigerant flowing out from the first radiator 31 can be ensured
so that the efficiency of the refrigeration and air-conditioning
apparatus can be significantly improved.
[0073] Even if an HFC-based refrigerant, an HC-based refrigerant,
an HFO-based refrigerant, or ammonia is used as the first
refrigerant flowing through the first refrigerant circuit, the
efficiency of the refrigeration and air-conditioning apparatus is
improved by ensuring a large degree of subcooling for the
refrigerant flowing out from the first radiator 31. The efficiency
of the refrigeration and air-conditioning apparatus is improved
especially when the first refrigerant in the first refrigerant
circuit is carbon dioxide and transfers heat at a critical point or
higher.
[0074] Although the second refrigerant circuit is described as
being a vapor compression refrigeration cycle in Embodiment 3, the
second refrigerant may alternatively be water or brine
(antifreeze), such as an ethylene glycol aqueous solution, and the
second compressor 40 may alternatively be a pump.
[0075] FIG. 8 is a refrigerant circuit diagram illustrating another
example of the refrigeration and air-conditioning apparatus
according to Embodiment 3 of the present invention.
[0076] In the refrigeration and air-conditioning apparatus shown in
FIG. 8, the first radiator 31 is omitted from the configuration of
the refrigeration and air-conditioning apparatus shown in FIG. 7,
and the first refrigerant, which is high-temperature high-pressure
vapor, discharged from the first compressor 30 is entirely cooled
at the heat exchanger 10. In other words, the refrigeration and
air-conditioning apparatus shown in FIG. 8 is a so-called
secondary-loop refrigeration and air-conditioning apparatus. In
this case, the heat exchanger 10 is used as the first radiator 31.
In the refrigeration and air-conditioning apparatus shown in FIG.
8, the amount of heat exchange required in the heat exchanger 10 is
increased, and the percentage of volume occupying the overall
refrigeration and air-conditioning apparatus becomes larger than in
the case where the first radiator 31 is provided. With the heat
exchanger 10 made compact, the advantage in which the entire
refrigeration and air-conditioning apparatus is made compact is
further increased.
[0077] FIG. 9 is a refrigerant circuit diagram illustrating another
example of the refrigeration and air-conditioning apparatus
according to Embodiment 3 of the present invention.
[0078] The refrigeration and air-conditioning apparatus shown in
FIG. 9 has a refrigerant circuit in which the first compressor 30,
the first radiator 31, the first pressure reducing device 32, and
the first cooling unit 33 are connected in that order. Furthermore,
the refrigeration and air-conditioning apparatus shown in FIG. 9
has a bypass pipe 52. The bypass pipe 52 has one end connected
between the first radiator 31 and the first pressure reducing
device 32 and other end connected to an injection port 53, which is
provided at an intermediate position in a refrigerant compression
process in the first compressor 30, or between the compressor 30
and the first cooling unit 33, although not shown here. The heat
exchanger 10 is disposed between the first radiator 31 and the
first pressure reducing device 32 in the refrigerant circuit and at
an intermediate position of the bypass pipe 52. With regard to the
heat exchanger 10, the first inlet header 3 is connected to the
first radiator 31, and the first outlet header 4 is connected to
the first pressure reducing device 32. Furthermore, with regard to
the heat exchanger 10, the second inlet header 5 is connected to a
bypass pressure reducing device 51, and the second outlet header 6
is connected to the injection port 53 or between the compressor 30
and the first cooling unit 33, although not shown here.
[0079] A refrigerant (i.e., low-temperature fluid) decompressed by
the bypass pressure reducing device 51 changes into a
low-temperature two-phase gas-liquid state, exchanges heat at the
heat exchanger 10 with a refrigerant (i.e., high-temperature fluid)
flowing out from the first radiator 31, and is then transported to
the injection port 53 of the first compressor 30. A refrigerant
such as an HFC-based refrigerant, an HC-based refrigerant, an
HFO-based refrigerant, ammonia, and carbon dioxide is used in the
refrigeration and air-conditioning apparatus shown in FIG. 9.
[0080] In the refrigeration and air-conditioning apparatus having
such a configuration, a large degree of subcooling for the
refrigerant flowing out from the first radiator 31 can be ensured
so that the efficiency of the refrigeration and air-conditioning
apparatus can be significantly improved.
[0081] Furthermore, in the refrigeration and air-conditioning
apparatus shown in FIG. 9, the higher the saturation temperature
(i.e., gas-liquid equilibrium temperature) of the low-temperature
fluid flowing into the injection port 53 from the heat exchanger 10
is, the higher the efficiency of the first compressor 30 is, thus
also allowing for a reduction of required power. By cooling the
outlet of the first radiator 31 as shown in FIG. 9, a sufficiently
large temperature difference between the high-temperature fluid and
the low-temperature fluid can be ensured in the heat exchanger 10
especially when the outdoor air temperature is high and the
temperature of the high-temperature fluid at the outlet of the
first radiator 31 is relatively high. Therefore, the temperature of
the low-temperature fluid flowing into the injection port 53 can be
maintained at a higher level, thereby ensuring high efficiency of
the first compressor 30.
[0082] If the second end of the bypass pipe 52 is connected between
the first compressor 30 and the first cooling unit 33, the flow
rate of refrigerant flowing through the first cooling unit 33 can
be reduced without reducing the refrigeration effect, as compared
with a case where the heat exchanger 10 is not used. This is
effective especially if the pipe length between the first
compressor 30 and the first cooling unit 33 is large since
deterioration in performance caused by an increase in pressure loss
can be suppressed.
[0083] Accordingly, with the compact, high-performance heat
exchanger 10 installed, a refrigeration and air-conditioning
apparatus that is compact and has the above-described advantages
can be obtained.
Embodiment 4
[0084] In the heat exchanger 10 described in each of Embodiment 1
and Embodiment 2, the first flat pipes 1 through which the
high-temperature fluid flows and the second flat pipes 2 through
which the low-temperature fluid flows are formed independently of
each other, and the first flat pipes 1 and the second flat pipes 2
are stacked such that the flat surfaces thereof are joined together
by soldering or the like. In other words, in the heat exchanger 10
described in each of Embodiment 1 and Embodiment 2, the refrigerant
passages through which the high-temperature fluid flows and the
refrigerant passages through which the low-temperature fluid flows
are formed in separate components. Alternatively, in the heat
exchanger 10, the refrigerant passages through which the
high-temperature fluid flows and the refrigerant passages through
which the low-temperature fluid flows may be formed in the same
component (in other words, the first passage section and the second
passage section according to the present invention may be
integrally formed). The heat exchanger 10 having such a
configuration may be installed in the refrigeration and
air-conditioning apparatus according to Embodiment 3. In Embodiment
4, items not described in particular are the same as those in
Embodiment 1 to Embodiment 3.
[0085] FIG. 10 includes structural diagrams of a heat exchanger
according to Embodiment 4 of the present invention. Specifically,
FIG. 10(a) is a perspective view of the heat exchanger 10, and FIG.
10(b) is a diagram as viewed along an arrow A in FIG. 10(a).
[0086] As shown in FIG. 10, a plurality of first refrigerant
passages 101a through which a first refrigerant (e.g., a
high-temperature fluid) flows extend through a main body 110 of the
heat exchanger 10 according to Embodiment 4 in, for example, the
longitudinal direction (i.e., the up-down direction in FIG. 10). By
arranging these first refrigerant passages 101a in parallel to each
other, a first refrigerant path 101 is formed. Moreover, a
plurality of second refrigerant passages 102a through which a
second refrigerant (e.g., a low-temperature fluid) flows extend
through the main body 110 in, for example, the longitudinal
direction (i.e., the up-down direction in FIG. 10). By arranging
these second refrigerant passages 102a in parallel to each other, a
second refrigerant path 102 is formed. The first refrigerant path
101 and the second refrigerant 102 are disposed such that the
parallel-arranged direction of the first refrigerant passages 101a
and the parallel-arranged direction of the second refrigerant
passages 102a are aligned with each other. In the heat exchanger 10
shown in FIG. 10, the first refrigerant path 101 (i.e., the first
refrigerant passages 101a) and the second refrigerant path 102
(i.e., the second refrigerant passages 102a) are vertically
disposed.
[0087] The expression "aligned" used here does not imply that the
parallel-arranged direction of the first refrigerant passages 101a
is exactly parallel to the parallel-arranged direction of the
second refrigerant passages 102a, but indicates that the
parallel-arranged directions of the two are substantially aligned
with each other. Therefore, the expression "the parallel-arranged
directions of the two are aligned with each other" will be used in
Embodiment 4 even if the parallel-arranged direction of the first
refrigerant passages 101a and the parallel-arranged direction of
the second refrigerant passages 102a are somewhat tilted.
[0088] In other words, in Embodiment 4, the first refrigerant path
101 and the second refrigerant path 102 are integrally formed. The
main body 110 having the first refrigerant path 101 and the second
refrigerant path 102 is composed of, for example, aluminum or an
aluminum alloy, copper or a copper alloy, steel, or a stainless
alloy, and is manufactured by extrusion, pultrusion or the
like.
[0089] One of two ends of the main body 110 in the refrigerant
flowing direction is provided with a second inlet communication
hole 105a that extends in the parallel-arranged direction of the
second refrigerant passages 102a and communicates with all of the
second refrigerant passages 102a. The other end is provided with a
second outlet communication hole 106a that extends in the
parallel-arranged direction of the second refrigerant passages 102a
and communicates with all of the second refrigerant passages 102a.
In other words, in the heat exchanger 10 shown in FIG. 10, the
second inlet communication hole 105a and the second outlet
communication hole 106a are horizontally disposed.
[0090] Similarly, of the two ends of the main body 110 in the
refrigerant flowing direction, the one end that is provided with
the second outlet communication hole 106a is provided with a first
inlet communication hole 103a that extends in the parallel-arranged
direction of the first refrigerant passages 101a and communicates
with all of the first refrigerant passages 101a. Moreover, of the
two ends of the main body 110 in the refrigerant flowing direction,
the other end that is provided with the second inlet communication
hole 105a is provided with a first outlet communication hole 104a
that extends in the parallel-arranged direction of the first
refrigerant passages 101a and communicates with all of the first
refrigerant passages 101a. In other words, in the heat exchanger 10
shown in FIG. 10, the first inlet communication hole 103a and the
first outlet communication hole 104a are horizontally disposed.
[0091] Furthermore, the first inlet communication hole 103a and the
second outlet communication hole 106a are slightly displaced
relative to each other in the refrigerant flowing direction of the
first refrigerant passages 101a (in other words, the second
refrigerant passages 102a). Moreover, the first outlet
communication hole 104a and the second inlet communication hole
105a are slightly displaced relative to each other in the
refrigerant flowing direction of the first refrigerant passages
101a (in other words, the second refrigerant passages 102a).
[0092] The extending direction of the first inlet communication
hole 103a and the first outlet communication hole 104a do not
necessarily need to be orthogonal to the direction of the first
refrigerant passages 101a. Furthermore, the extending direction of
the second inlet communication hole 105a and the second outlet
communication hole 106a do not necessarily need to be orthogonal to
the direction of the second refrigerant passages 102a.
[0093] The first inlet communication hole 103a, the first outlet
communication hole 104a, the second inlet communication hole 105a,
and the second outlet communication hole 106a each have one open
end and are respectively connected to a first inlet connection pipe
103, a first outlet connection pipe 104, a second inlet connection
pipe 105, and a second outlet connection pipe 106 so as to
communicate with the outside. The other end of each of the first
inlet communication hole 103a, the first outlet communication hole
104a, the second inlet communication hole 105a, and the second
outlet communication hole 106a is closed by a sealing member or the
like.
[0094] In FIG. 10, the open (or closed) ends of the first inlet
communication hole 103a, the first outlet communication hole 104a,
the second inlet communication hole 105a, and the second outlet
communication hole 106a are all located at the same side. However,
the open (or closed) ends of the first inlet communication hole
103a, the first outlet communication hole 104a, the second inlet
communication hole 105a, and the second outlet communication hole
106a are not limited to the positions shown in FIG. 10 and do not
need to be located at the same side so long as each communication
hole has an open end and a closed end.
[0095] Both ends of each of the plurality of first refrigerant
passages 101a and second refrigerant passages 102a extending
through the main body 110 in the longitudinal direction are sealed
by a process such as pinching or sealed by using sealing members
(not shown).
[0096] The heat exchanger 10 according to Embodiment 4 is assumed
to be used in a position that makes the low-temperature fluid and
the high-temperature fluid flow in the up-down direction as shown
in FIG. 10. Furthermore, in the heat exchanger 10 according to
Embodiment 4, the low-temperature fluid in a two-phase gas-liquid
state is assumed to flow into the second refrigerant passages 102a
of the second refrigerant path via the second inlet connection pipe
105 and the second inlet communication hole 105a. Therefore, in the
heat exchanger 10 according to Embodiment 4, the second inlet
communication hole 105a is disposed at the following position based
on the information obtained from the tests shown in FIGS. 3 to 5 in
Embodiment 1, that is, the ranges of the aforementioned position
angles .alpha., .beta., and .gamma. providing excellent heat
transfer characteristics.
[0097] Specifically, when the second inlet communication hole 105a
is observed in the central-axis direction of the second inlet
communication hole 105a, the central axis of the second inlet
communication hole 105a is disposed at a position that is aligned
with a connection section between the second inlet communication
hole 105a and the second refrigerant path 102 (i.e., the second
refrigerant passages 102a), or at a position away from the first
refrigerant path 101 (i.e., the first refrigerant passages 101a)
relative to the connection section.
[0098] Thus, in the heat exchanger 10 according to Embodiment 4,
the second refrigerant path 102 and the second inlet header 5 are
connected with a position angle .alpha. in a range of
0.degree..ltoreq..alpha.<110.degree. (or
-110.degree.<.alpha..ltoreq.0 if the positive direction is the
same as in FIG. 3).
[0099] The first refrigerant path 101, the second refrigerant path
102, the first inlet communication hole 103a, the first outlet
communication hole 104a, the second inlet communication hole 105a,
and the second outlet communication hole 106a respectively
correspond to "first passage section", "second passage section",
"first inlet header", "first outlet header", "second inlet header",
and "second outlet header" according to the present invention.
[0100] Next, a heat exchanging process between the high-temperature
fluid and the low-temperature fluid in the heat exchanger 10
according to Embodiment 4 will be described with reference to FIG.
10.
[0101] The high-temperature fluid flows into the first inlet
communication hole 103a via the first inlet connection pipe 103,
flows through the first refrigerant path 101 and the first outlet
communication hole 104a in that order, and then flows out from the
first outlet connection pipe 104. On the other hand, the
low-temperature fluid in a two-phase gas-liquid state flows into
the second inlet communication hole 105a via the second inlet
connection pipe 105, flows through the second refrigerant path 102
and the second outlet communication hole 106a in that order, and
then flows out from the second outlet connection pipe 106. During
this time, the high-temperature fluid flowing through the first
refrigerant path 101 and the low-temperature fluid flowing through
the second refrigerant path 102 exchange heat in a countercurrent
manner via a partition wall between the refrigerant paths.
[0102] In the heat exchanger 10 having the configuration as in
Embodiment 4, when the second inlet communication hole 105a is
observed in the central-axis direction of the second inlet
communication hole 105a, the central axis of the second inlet
communication hole 105a is disposed at a position that is aligned
with the connection section between the second inlet communication
hole 105a and the second refrigerant path 102 (i.e., the second
refrigerant passages 102a), or at a position away from the first
refrigerant path 101 (i.e., the first refrigerant passages 101a)
relative to the connection section. Consequently, the position
angle .alpha. when the low-temperature fluid in the two-phase
gas-liquid state flows into the second refrigerant path 102 from
the second inlet communication hole 105a is in a range of
0.degree..ltoreq..alpha.<110.degree.. Therefore, the
low-temperature fluid in the two-phase gas-liquid state is readily
distributed to the second refrigerant passages 102a of the second
refrigerant path 102 with a substantially uniform gas-to-liquid
ratio, whereby a heat exchanger 10 with stable performance can be
obtained.
[0103] It is apparent from Embodiment 1 that, if the direction
indicated by an arrow in FIG. 10(b) is defined as the positive
direction, the distribution characteristics of a gaseous phase
component and a liquid phase component in the low-temperature fluid
are optimal when 80.degree.<.alpha.<100.degree.. Moreover,
the distance between the first refrigerant path 101 and the second
refrigerant path 102 located next to each other can be shortened.
Therefore, if the direction indicated by the arrow in FIG. 10(b) is
defined as the positive direction, the second inlet communication
hole 105a is formed so as to satisfy
80.degree.<.alpha.<100.degree., thereby further suppressing
heat resistance in the main body 110 due to heat conductivity and
further improving the performance of the heat exchanger 10.
[0104] With the first refrigerant path 101 and the second
refrigerant path 102 formed integrally in the main body 110, the
following various advantages can also be achieved.
[0105] First, heat resistance generated, in case that the passages
through which the high-temperature fluid flows and the passages
through which the low-temperature fluid flows are formed in
separate components, at joint surfaces of these components is
suppressed, whereby the heat exchanging performance of the heat
exchanger 10 can be improved.
[0106] Furthermore, because the first inlet communication hole 103a
and the first outlet communication hole 104a are provided inside
the main body 110 of the heat exchanger 10, an additional header
pipe for connecting to the first refrigerant path 101 is not
necessary, thereby achieving compactness of the heat exchanger 10,
as well as simplifying the manufacturing process. The same applies
to the second inlet communication hole 105a and the second outlet
communication hole 106a with respect to the second refrigerant path
102.
[0107] Furthermore, since the first inlet communication hole 103a
and the second outlet communication hole 106a are slightly
displaced relative to each other in the fluid flowing direction,
and the first outlet communication hole 104a and the second inlet
communication hole 105a are slightly displaced relative to each
other in the fluid flowing direction, the distance between the
first refrigerant path 101 and the second refrigerant path 102
located next to each other can be shortened, as compared with a
case where the holes are not displaced, thereby achieving
compactness of the heat exchanger 10.
[0108] In the heat exchanger 10 according to Embodiment 4, although
the first refrigerant passages 101a and the second refrigerant
passages 102a are rectangular in cross section, as shown in FIG.
10, the cross-sectional shapes thereof are not limited to a
rectangular shape. The cross-sectional shape of the first
refrigerant passages 101a and the second refrigerant passages 102a
may be polygonal, or circular for enhancing the pressure resisting
performance, for example. The first refrigerant passages 101a and
the second refrigerant passages 102a may certainly be elongated or
ellipsoidal in cross section. In this case, it is needless to say
that the cross-sectional shape of the first refrigerant passages
101a and the cross-sectional shape of the second refrigerant
passages 102a do not need to be the same. Furthermore, in order to
enhance the heat transfer performance, the heat transfer area may
be increased by providing a groove in the inner surface of each of
the first refrigerant passages 101a and the second refrigerant
passages 102a. In this case, these grooves may be processed
simultaneously during the extrusion process or the pultrusion
process of the main body 10 so that the manufacturing process can
be simplified.
[0109] Although the number of first refrigerant passages 101a in
the first refrigerant path 101 and the number of second refrigerant
passages 102a in the second refrigerant path 102 are the same in
the heat exchanger 10 according to Embodiment 4, as shown in FIG.
10, the numbers thereof are not limited to this relationship.
Specifically, the numbers may be varied in accordance with the
operating conditions or the flow property values of the
high-temperature fluid and the low-temperature fluid in the heat
exchanger 10 so that a preferred heat exchanger 10 with high heat
transfer performance and low pressure loss is achieved.
[0110] Although the high-temperature fluid flowing through the
first refrigerant path 101 and the low-temperature fluid flowing
through the second refrigerant path 102 exchange heat in a
countercurrent manner, the two fluids may alternatively exchange
heat in a parallel current manner. For example, by making the
high-temperature fluid flow in from the first inlet connection pipe
103 and making the low-temperature fluid flow in from the second
outlet connection pipe 106, the high-temperature fluid and the
low-temperature fluid are made to flow in parallel to each
other.
[0111] Furthermore, although the heat exchanger 10 in FIG. 10 is
described as being used in a position that makes the
low-temperature fluid and the high-temperature fluid flow in the
up-down direction, the installation position of the heat exchanger
10 according to Embodiment 4 in which the first refrigerant path
101 and the second refrigerant path 102 are integrally formed is
not limited to the position shown in FIG. 10.
[0112] FIG. 11 includes structural diagrams illustrating another
example of the heat exchanger according to Embodiment 4 of the
present invention. Specifically, FIG. 11(a) is a perspective view
of the heat exchanger 10, and FIG. 11(b) is a diagram as viewed
along an arrow A in FIG. 11(a).
[0113] The heat exchanger 10 shown in FIG. 11 is assumed to be used
in a position that makes the low-temperature fluid and the
high-temperature fluid flow in the left-right direction (i.e.,
substantially horizontal direction). In other words, in the heat
exchanger 10 shown in FIG. 11, the first refrigerant path 101
(i.e., the first refrigerant passages 101a) and the second
refrigerant path 102 (i.e., the second refrigerant passages 102a)
are horizontally disposed. The remaining configuration is similar
to that in the heat exchanger 10 shown in FIG. 10 and exhibits
similar advantages. Since components given the same reference
numerals in FIGS. 10 and 11 have the same functions and operate in
the same manner, descriptions of the functions and operations
thereof will be omitted.
[0114] In the heat exchanger 10 having the configuration shown in
FIG. 11, when the second inlet communication hole 105a is observed
in the central-axis direction of the second inlet communication
hole 105a, the central axis of the second inlet communication hole
105a may similarly be disposed at a position that is aligned with
the connection section between the second inlet communication hole
105a and the second refrigerant path 102 (i.e., the second
refrigerant passages 102a), or at a position away from the first
refrigerant path 101 (i.e., the first refrigerant passages 101a)
relative to the connection section. Consequently, the position
angle .alpha. when the low-temperature fluid in the two-phase
gas-liquid state flows into the second refrigerant path 102 from
the second inlet communication hole 105a can beset in a range of
0.degree.<.alpha..ltoreq.90.degree.. Therefore, the
low-temperature fluid in the two-phase gas-liquid state is readily
distributed to the second refrigerant passages 102a of the second
refrigerant path 102 with a substantially uniform gas-to-liquid
ratio, whereby a heat exchanger 10 with stable performance can be
obtained. Although a range of 80.degree.<.alpha.<100.degree.
is the most preferable as the distribution characteristics, in the
case of Embodiment 4, as .alpha. approaches closer to 0.degree.
from 90.degree. (specifically, as the central axis of the second
inlet communication hole 105a is disposed farther away from the
first refrigerant path 101), the distance between the first
refrigerant path 101 and the second refrigerant path 102 located
next to each other can be shorter. Therefore, a position angle
.alpha. that allows for reduced heat resistance by heat
conductivity and improved performance may at least be in the range
of 0.degree.<.alpha..ltoreq.90.degree..
[0115] As shown in FIGS. 10 and 11, with regard to the heat
exchanger 10 according to Embodiment 4, a usage mode in which the
low-temperature fluid in the two-phase gas-liquid state is made to
flow in from the second outlet connection pipe 106 and flow out
from the second inlet connection pipe 105 may also be assumed.
Therefore, when the second outlet communication hole 106a is
observed in the central-axis direction of the second outlet
communication hole 106a, the central axis of the second outlet
communication hole 106a is disposed at a position aligned with a
connection section between the second outlet communication hole
106a and the second refrigerant path 102 (i.e., the second
refrigerant passages 102a), or at a position away from the first
refrigerant path 101 (i.e., the first refrigerant passages 101a)
relative to the connection section.
REFERENCE SIGNS LIST
[0116] 1 first flat pipe, 1a inflow segment, 1b bent segment, 1c
heat exchanging segment, 1d outflow segment, 2 second flat pipe, 2a
inflow segment, 2b bent segment, 2c heat exchanging segment, 2d
outflow segment, 2A second flat pipe, 2Aa inflow segment, 2Ab bent
segment, 2Ac heat exchanging segment, 2Ad outflow segment, 2B
second flat pipe, 2Ba inflow segment, 2Bb bent segment, 2Bc heat
exchanging segment, 2Bd outflow segment, 3 first inlet header, 4
first outlet header, 5 second inlet header, 5A second inlet header,
5B second inlet header, 6 second outlet header, 6A second outlet
header, 6B second outlet header, 10 heat exchanger, 21
through-hole, 30 first compressor, 31 first radiator, 32 first
pressure reducing device, 33 first cooling unit, 40 second
compressor, 41 second radiator, 42 second pressure reducing device,
52 bypass pipe, 53 injection port, 101 first refrigerant path, 101a
first refrigerant passage, 102 second refrigerant path, 102a second
refrigerant passage, 103 first inlet connection pipe, 103a first
inlet communication hole, 104 first outlet connection pipe, 104a
first outlet communication hole, 105 second inlet connection pipe,
105a second inlet communication hole, 106 second outlet connection
pipe, 106a second outlet communication hole, 110 main body.
* * * * *