U.S. patent application number 12/990270 was filed with the patent office on 2011-03-03 for heat exchanger and air conditioning system.
Invention is credited to Hideaki Asai, Yoonmyung Kang, Katsuhiro Kawabata, Keisuke Tanimoto.
Application Number | 20110048049 12/990270 |
Document ID | / |
Family ID | 41254933 |
Filed Date | 2011-03-03 |
United States Patent
Application |
20110048049 |
Kind Code |
A1 |
Asai; Hideaki ; et
al. |
March 3, 2011 |
HEAT EXCHANGER AND AIR CONDITIONING SYSTEM
Abstract
A heat exchanger installed under the ground or water includes an
outer pipe installed vertically or installed inclinedly under the
ground or water; and a heating heat-transfer pipe inserted into the
outer pipe, and evaporating refrigerant injected thereto. A heat
medium is sealed in the outer pipe. A heat exchange is performed by
using a change in phase of the heat medium and a heat medium
guiding section for guiding the heat medium condensed on an outer
surface of the heating heat-transfer pipe to an inner wall surface
of the outer pipe by using surface tension of the heat medium or by
reducing an angle of contact on the inner surface is formed in an
upper section of the outer pipe.
Inventors: |
Asai; Hideaki; (Osaka,
JP) ; Kawabata; Katsuhiro; (Osaka, JP) ;
Tanimoto; Keisuke; (Osaka, JP) ; Kang; Yoonmyung;
(Osaka, JP) |
Family ID: |
41254933 |
Appl. No.: |
12/990270 |
Filed: |
April 30, 2009 |
PCT Filed: |
April 30, 2009 |
PCT NO: |
PCT/JP2009/001969 |
371 Date: |
October 29, 2010 |
Current U.S.
Class: |
62/260 ;
165/104.26; 165/133; 165/45 |
Current CPC
Class: |
Y02B 10/40 20130101;
Y02E 60/14 20130101; Y02E 60/142 20130101; F24T 10/30 20180501;
Y02E 10/10 20130101; F25B 30/06 20130101; F28D 20/0052
20130101 |
Class at
Publication: |
62/260 ; 165/45;
165/104.26; 165/133 |
International
Class: |
F25D 31/00 20060101
F25D031/00; F24J 3/08 20060101 F24J003/08; F28D 15/04 20060101
F28D015/04; F28F 13/00 20060101 F28F013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 30, 2008 |
JP |
2008-118211 |
Claims
1. A heat exchanger, comprising: an outer pipe installed vertically
or installed inclinedly under the ground or water; a heating
heat-transfer pipe which is inserted into the outer pipe, and which
evaporates refrigerant injected thereto; and a heat medium sealed
in the outer pipe, wherein a heat exchange is performed by using a
change in phase of the heat medium; and a heat medium guiding
section for guiding the heat medium condensed on an outer surface
of the heating heat-transfer pipe to an inner wall surface of the
outer pipe by using surface tension of the heat medium or by
reducing an angle of contact on the inner surface is formed in an
upper section of the outer pipe.
2. The heat exchanger of claim 1, wherein the heating heat-transfer
pipe is formed in coiled shape.
3. The heat exchanger of claim 1, wherein a wick is provided along
the inner wall surface of the outer pipe inside the outer pipe.
4. The heat exchanger of claim 1, wherein grooves for holding the
heat medium by using surface tension of the heat medium or by
reducing an angle of contact on the inner wall surface are formed
in the inner wall surface of the outer pipe.
5. An air conditioning system, comprising: the heat exchanger of
claim 1, wherein a refrigeration cycle is performed.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger installed
under the ground or water, and to an air conditioning system using
the heat exchanger.
BACKGROUND ART
[0002] An example of a so-called "heat-pump heating system" which
performs heating by a refrigeration cycle is a system in which
ground heat or heat contained in water is used as a heat source to
evaporate refrigerant. For example, in a heat-pump heating system
using ground heat, an underground heat exchanger for recovering
ground heat from the ground is used (see, e.g., Patent Document 1).
In the heat exchanger of Patent Document 1, a pipe (referred to as
a "buried pipe" in the specification) filled with a heat medium is
buried under the ground, and the heat medium inside the buried pipe
is evaporated by ground heat. A pipe is branched from the buried
pipe, and then the heat exchanger is attached to the branched pipe.
Heat recovered in the heat exchanger is used as a heat source of
the heat-pump heating system.
CITATION LIST
Patent Document
[0003] PATENT DOCUMENT 1: International Publication No.
WO2004/111559
SUMMARY OF THE INVENTION
Technical Problem
[0004] However, in, e.g., an underground heat exchanger collecting
heat from soil, when using the compact underground heat exchanger,
it is difficult to obtain a sufficient amount of heat with heat
exchange capability of the conventional heat exchanger (underground
heat exchanger) due to large heat transfer resistance of the soil.
Thus, when an attempt is made to obtain a sufficient amount of heat
in, e.g., a so-called "vertical underground heat exchanger" buried
in the vertical direction, it is necessary to bury the underground
heat exchanger to great depth. Specifically, there is an example in
which a burial depth of approximately 100 m is required for an
underground heat exchanger of a household heating system. Such a
requirement of the burial depth of the underground heat exchanger
causes a problem on its installation cost. As in Patent Document 1,
the heat exchanger for refrigerant flowing through a heat pump is
directly installed near the ground surface, and ground heat is
recovered by using a change in phase of the heat medium. However,
in the pipe, an area where working fluid is condensed is smaller
than an area where the working fluid is evaporated, resulting in
poor heat balance between the vaporization and the condensation.
Although the condensed working fluid flows from an upper section of
the pipe, a long wall surface of the pipe is not uniformly
moistened. That is, a heat exchange using ground heat is not
effectively performed.
[0005] In addition, in a broadly-used system in which water
circulates inside the underground heat exchanger to use heat from
such circulating water, a tube line for running water into the pipe
buried to the above-described depth, and a pump for transferring
the heat medium flowing in the tube are required, and therefore
there is a problem that power consumption of the pump degrades
efficiency of the entire heating system.
[0006] The present invention has been made in view of the foregoing
problems, and it is an object of the invention to improve heat
exchange capability in a heat exchanger arranged under the ground
or water.
Solution to the Problem
[0007] In order to solve the foregoing problems, a first aspect of
the invention is intended for a heat exchanger including an outer
pipe (51) installed vertically or installed inclinedly under the
ground or water; a heating heat-transfer pipe (80) which is
inserted into the outer pipe (51), and which evaporates refrigerant
injected thereto; and a heat medium sealed in the outer pipe (51).
In the heat exchanger, a heat exchange is performed by using a
change in phase of the heat medium, and the outer pipe (51) and the
heating heat-transfer pipe (80) are arranged so that the liquid
heat medium is guided between an inner wall surface of the outer
pipe (51) and an outer wall surface of the cooling heat-transfer
pipe (52).
[0008] This allows a heat medium guiding section (52) to guide the
heat medium condensed on an outer surface of the heating
heat-transfer pipe (80) to the inner wall surface of the outer pipe
(51). While the heat medium guided to the inner wall surface flows
down along the inner wall surface, such a heat medium is adhered
and spreads in a circumferential direction of the inner wall
surface, thereby forming a liquid film.
[0009] A second aspect of the invention is intended for the heat
exchanger of the first aspect of the invention, in which the
heating heat-transfer pipe (80) is formed in coiled shape.
[0010] This allows the coiled heating heat-transfer pipe (80) to
guide the condensed heat medium to the inner wall surface of the
outer pipe (51).
[0011] A third aspect of the invention is intended for the heat
exchanger of the first aspect of the invention, in which a wick
(90) is provided along the inner wall surface of the outer pipe
(51) inside the outer pipe (51).
[0012] Thus, the heat medium condensed on an outer side of the
heating heat-transfer pipe (80) penetrates the wick (90), thereby
allowing the heat medium to contact a broad area of the inner wall
surface of the outer pipe (51).
[0013] A fourth aspect of the invention is intended for the heat
exchanger of the first aspect of the invention, in which grooves
(100) for holding the heat medium by using surface tension of the
heat medium or by reducing an angle of contact on the inner wall
surface are formed in the inner wall surface of the outer pipe
(51).
[0014] This allows the grooves (100) to hold the liquid heat medium
flowing in the outer pipe (51), and allows the held liquid
refrigerant to contact the inner wall surface of the outer pipe
(51).
[0015] A fifth aspect of the invention is intended for an air
conditioning system including the heat exchanger of the first
aspect of the invention, in which a refrigeration cycle' is
performed.
[0016] This allows the air conditioning system to perform a heating
operation using ground heat as a heat source. In the heating
operation, the heat medium condensed on the outer surface of the
heating heat-transfer pipe (80) is guided to the inner wall surface
of the outer pipe (51). While the heat medium guided to the inner
wall surface flows down along the inner wall surface, such a heat
medium is adhered to and spreads on the inner wall surface, thereby
forming the liquid film. The heat medium forming the liquid film is
evaporated again by collecting heat contained in the ground or
water through the wall surface. The heat medium transfers heat
contained in the ground or water to the heating heat-transfer pipe
(80) which is a vaporization section of the air conditioning
system, by using the change in phase upon
evaporation/condensation.
Advantages of the Invention
[0017] According to the first aspect of the invention, the
condensed heat medium is adhered and spreads in the circumferential
direction of the inner wall surface of the outer pipe (51), thereby
forming the liquid film. Thus, a non-uniform flow of the heat
medium and non-uniform moistening of the inner wall surface in a
length direction (i.e., axial direction) of the outer pipe (51) can
be reduced or prevented. This allows the liquid heat medium to be
efficiently evaporated by contacting the inner wall surface of the
outer pipe (51). Consequently, heat exchange efficiency of the heat
exchanger is further improved.
[0018] According to the second aspect of the invention, the coiled
heating heat-transfer pipe (80) guides the condensed heat medium to
the inner wall surface of the outer pipe (51), and therefore a
sufficient length of the heat medium guiding section (52) can be
ensured. Consequently, the heat exchange efficiency is further
improved.
[0019] According to the third aspect of the invention, the liquid
heat medium flowing in the outer pipe (51) penetrates and is held
in the wick (90), and the held liquid refrigerant contacts the
inner wall surface of the outer pipe (51). Thus, uniform moistening
of the inner wall surface of the outer pipe (51) can be ensured,
thereby further improving the heat exchange capability.
[0020] According to the fourth aspect of the invention, the liquid
heat medium flowing in the outer pipe (51) penetrate and is held in
the grooves (100), and the held liquid refrigerant contacts the
inner wall surface of the outer pipe (51). Thus, the uniform
moistening of the inner wall surface of the outer pipe (51) can be
ensured, thereby further improving the heat exchange
capability.
[0021] According to the fifth aspect of the invention, in the air
conditioning system, an outdoor unit (air heat exchanger) is not
required, as well as defrosting operation is not required
regardless of outdoor temperature. Thus, the heating operation can
be performed with high efficiency. The liquid heat medium smoothly
circulates in the outer pipe (51), and therefore a heat transfer
using the change in phase of the heat medium is efficiently
performed between the heating heat-transfer pipe (80) and the inner
surface of the outer pipe (51). Consequently, the heat exchange
capability of the heat exchanger in the heating operation is
improved. Such improvement of the heat exchange capability allows a
reduction in size of the heat exchanger, and a reduction in cost of
a heating system can be also expected.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 is a system diagram of an air conditioning system
including an underground heat exchanger of an embodiment of the
present invention.
[0023] FIG. 2 is a longitudinal sectional view illustrating a
configuration of the underground heat exchanger.
[0024] FIG. 3 is a view schematically illustrating a state in which
the underground heat exchanger is installed under the ground.
[0025] FIG. 4 is a view illustrating a configuration of a heat
medium guiding section, and movement of a heat medium.
[0026] FIG. 5 is a view schematically illustrating a state in which
a heat exchanger (50) is installed under water.
[0027] FIGS. 6(A) and 6(B) are views schematically illustrating a
state in which the heat exchanger (50) is inclinedly installed.
[0028] FIG. 7(A) is a cross-sectional view in an example of other
configuration of an outer pipe. FIG. 7(B) is a perspective view
with a part of the outer pipe being removed.
[0029] FIG. 8 is a cross-sectional view illustrating an example of
other configuration of the outer pipe.
DESCRIPTION OF EMBODIMENTS
[0030] Embodiments of the present invention will be described
hereinafter with reference to the drawings. The embodiments below
have been set forth merely for purposes of preferred examples in
nature, and are not intended to limit the scope, applications, and
use of the invention. In addition, in the description of
embodiments and variations below, the same reference numeral is
used throughout to refer to a component having the same function as
that of a component which is first described, and the description
thereof will not be repeated.
First Embodiment of the Invention
[0031] In a first embodiment, a heat exchanger installed under the
ground (underground heat exchanger) will be described as an example
of a heat exchanger of the present invention.
[0032] The underground heat exchanger of the embodiments of the
present invention is used for, e.g., a heat-pump air conditioning
system which can perform a heating operation. The underground heat
exchanger serves as an evaporator in the heating operation, and
collects heat from soil. Note that the "soil" includes layers
containing only dirt; water-bearing layers containing both of dirt
and water; and rock layers in which rocks are successively
distributed. That is, depending on a site and depth of
installation, the underground heat exchanger may exchange heat with
dirt, water contained in the ground, rocks, or all of them.
[0033] <Entire Configuration of Air Conditioning System>
[0034] FIG. 1 is a system diagram of an air conditioning system (1)
including a heat exchanger (underground heat exchanger) (50) of an
embodiment of the present invention. As illustrated in FIG. 1, the
air conditioning system (1) of the present embodiment includes a
refrigerant circuit (10). A compressor (20), an indoor heat
exchanger (30), an expansion valve (40), and the underground heat
exchanger (50) are connected to the refrigerant circuit (10). The
refrigerant circuit (10) is filled with refrigerant (working
fluid).
[0035] The compressor (20) sucks refrigerant through a suction port
to compress such refrigerant, and then discharges the compressed
refrigerant through a discharge port. Specifically, various
compressors such as a scroll compressor may be employed as the
compressor (20). In the refrigerant circuit (10), the suction port
of the compressor (20) is connected to the underground heat
exchanger (50) (specifically, an exit section (80c) which will be
described later), and the discharge port of the compressor (20) is
connected to the indoor heat exchanger (30).
[0036] The indoor heat exchanger (30) is an air heat exchanger for
exchanging heat between refrigerant and indoor air. In the air
conditioning system (1), the indoor heat exchanger (30) is
installed inside a so-called "indoor unit" arranged in a room to be
heated, and dissipates heat of high-pressure refrigerant sent from
the compressor (20), to indoor air. For example, a cross-fin type
fin-and-tube heat exchanger may be employed as the indoor heat
exchanger (30). An outflow hole of the indoor heat exchanger (30)
is connected to an inflow hole of the expansion valve (40), and
refrigerant from which heat is dissipated flows out to the
expansion valve (40) through such an outflow hole. An indoor fan
(31) is installed near the indoor heat exchanger (30). The indoor
fan (31) sends air-conditioned air to the room.
[0037] An outflow hole of the expansion valve (40) is connected to
the underground heat exchanger (50) (specifically, an entry section
(80a) which will be described later). The expansion valve (40)
expands refrigerant flowing from the indoor heat exchanger (30) to
reduce the pressure of such refrigerant to a predetermined pressure
level, and then discharges the refrigerant to the underground heat
exchanger (50).
[0038] The underground heat exchanger (50) collects heat for the
heating operation by using ground heat as a heat source. As
illustrated in FIG. 2, the underground heat exchanger (50) includes
an outer pipe (51) and a heating heat-transfer pipe (80).
[0039] The outer pipe (51) is formed in tubular shape with closed
ends, and is vertically buried under the ground in this example.
For example, FIG. 3 is a view schematically illustrating a state in
which the underground heat exchanger (50) is installed under the
ground. A geological layer includes, e.g., a layer mainly
containing dirt; a layer containing dirt and water; a layer mainly
containing water; and a rock layer in which rocks are successively
distributed. The underground heat exchanger (50) may be installed
in any of the geological layers. FIG. 3 illustrates the state in
which the underground heat exchanger (50) is installed so as to
cross such layers, but, e.g., the underground heat exchanger (50)
may be installed so that a heat exchange is performed only in any
of the above-described layers.
[0040] A predetermined amount of carbon dioxide (CO.sub.2) is
sealed in the outer pipe (51) as a heat medium. As described later,
the heat medium is evaporated by absorbing heat from soil through
an inner wall surface of the outer pipe (51), and is condensed by
dissipating heat at an outer wall surface of the heating
heat-transfer pipe (80) (specifically a body section (80b) which
will be described later). A heat medium guiding section (52)
(described later) for guiding the condensed heat medium to the
inner wall surface of the outer pipe (51) by using surface tension
of the heat medium, and by reducing an angle of contact on the
surface is formed in an upper section of the outer pipe (51).
[0041] The heating heat-transfer pipe (80) includes the entry
section (80a), the body section (80b), and the exit section
(80c).
[0042] The entry section (80a) is a pipe for injecting refrigerant
into the body section (80b), and the exit section (80c) is a pipe
for discharging refrigerant from the body section (80b). In the
present embodiment, both of the entry section (80a) and the exit
section (80c) are formed so as to be straight, and one end of each
of the entry section (80a) and the exit section (80c) is inserted
into the outer pipe (51) from above. In addition, both of the entry
section (80a) and the exit section (80c) are connected to the body
section (80b) inside the outer pipe (51).
[0043] The body section (80b) exchanges heat with the heat medium
flowing in the outer pipe (51), and then refrigerant injected into
the body section (80b) is evaporated. In the present embodiment,
the body section (80b) is formed in coiled shape, and is arranged
in an upper section inside the outer pipe (51). As described later,
the heat medium (vapor) is condensed on an outer surface of the
body section (80b) in the heating operation. The body section (80b)
defines the heat medium guiding section (52) for guiding the
condensed heat medium to the inner wall surface of the outer pipe
(51). Specifically, as illustrated in FIG. 4, an outer wall surface
of the body section (80b) is arranged in proximity to the inner
wall surface of the outer pipe (51). The condensed heat medium is
attracted and guided to the inner wall surface of the outer pipe
(51) between the wall surfaces by using the surface tension of the
heat medium, and by reducing the angle of contact on the surface. A
clearance is formed between the outer wall surface of the body
section (80b) and the inner wall surface of the outer pipe (51),
and the heat medium guided to the inner wall surface of the outer
pipe (51) flows down along the inner wall surface through the
clearance in the outer pipe (51).
[0044] Operation
[0045] Next, a process in the heating operation in the air
conditioning system (1) will be described.
[0046] First, when the refrigerant circuit (10) comes into
operation, compressed refrigerant (gaseous refrigerant) is
discharged through the discharge port of the compressor (20). Then,
the refrigerant discharged from the compressor (20) is sent to the
indoor heat exchanger (30). The refrigerant flowing into the indoor
heat exchanger (30) dissipates heat to indoor air in the indoor
heat exchanger (30). The indoor air is heated in the indoor heat
exchanger (30), and then the heated indoor air is sent back to the
room by the indoor fan (31). The refrigerant dissipating heat in
the indoor heat exchanger (30) is sent to the expansion valve (40).
The pressure of the refrigerant flowing into the expansion valve
(40) is reduced when passing through the expansion valve (40), and
then such refrigerant is sent to the body section (80b) through the
entry section (80a) of the heating heat-transfer pipe (80). The
injected refrigerant has two phases, i.e., gas-liquid phase.
[0047] In such a state, the heat medium is evaporated by ground
heat in the outer pipe (51), and is present as vapor. When such
vapor of the heat medium contacts the outer wall surface of the
body section (80b), the heat medium is condensed because the body
section (80b) absorbs its heat, and is changed into liquid. In the
heat medium guiding section (52), the liquid heat medium is
attracted between the outer wall surface of the body section (80b)
and the inner wall surface of the outer pipe (51) by using the
surface tension of the heat medium, and by reducing the angle of
contact on the surface. The attracted heat medium is guided to the
inner wall surface of the outer pipe (51), and then flows down
along the inner wall surface through the clearance between the
outer wall surface of the body section (80b) and the inner wall
surface of the outer pipe (51). In particular, the body section
(80b) is formed in coiled shape in the present embodiment, thereby
ensuring a sufficient length of the heat medium guiding section
(52). While the heat medium guided to the inner wall surface of the
outer pipe (51) flows down along the inner wall surface, such a
heat medium is adhered to and spreads on the inner wall surface,
and forms a liquid film. The heat medium forming the liquid film is
evaporated by absorbing ground heat from soil through the inner
wall surface of the outer pipe (51).
[0048] On the other hand, the body section (80b) of the heating
heat-transfer pipe (80) contacts the vapor of the heat medium
flowing in the outer pipe (51). Refrigerant flowing in the body
section (80b) is evaporated by absorbing heat from the vapor of the
heat medium through the body section (80b). As described above, the
underground heat exchanger (50) collects ground heat by using a
change in phase of the heat medium flowing in the outer pipe
(51).
[0049] The refrigerant evaporated in the body section (80b) of the
heating heat-transfer pipe (80) is discharged to the compressor
(20) through the exit section (80c). The compressor (20) sucks and
compresses such refrigerant, and then discharges the refrigerant to
the indoor heat exchanger (30) again. In the air conditioning
system (1), the above-described process is repeated to perform a
refrigeration cycle (heating operation in this example) in which
the underground heat exchanger (50) serves as the heat source to
compress refrigerant in the compressor (20).
[0050] As described above, according to the present embodiment, the
heat medium condensed on the outer wall surface of the heating
heat-transfer pipe (80) (body section (80b)) is guided to the inner
wall surface of the outer pipe (51) by the heat medium guiding
section (52), and then is adhered to and spreads on the inner wall
surface. That is, a non-uniform flow of the heat medium and
non-uniform moistening of the inner wall surface in a length
direction (i.e., axial direction) of the outer pipe (51) can be
reduced or prevented. Consequently, the liquid heat medium can be
efficiently evaporated by contacting the inner wall surface of the
outer pipe (51). This improves heat exchange capability in the
underground heat exchanger (50), and such improvement allows a
reduction in size of an underground heat exchanger. In addition,
because of the reduction in size, a reduction in cost of an air
conditioning system (heating system) can be expected.
Second Embodiment
[0051] The heat exchanger (50) may be installed under the ground,
as well as under water. An installation site specifically includes,
e.g., the sea, a lake, a pond, a pool, a water storage tank, a
river, and a sewage system. FIG. 5 is a view schematically
illustrating a state in which a heat exchanger (50) is installed
under water. In this figure, two examples (first and second
examples) are illustrated as examples of installation of the heat
exchanger (underwater heat exchanger) (50). The first example is an
example in which the heat exchanger (50) is installed in a water
storage tank or a pool. The second example is an example in which
the heat exchanger (50) is installed in the sea, a lake, or a pond.
Note that, in this figure, the "HP" means a body section of an air
conditioning system (1) (section other than the heat exchanger)
(the same holds true for the following).
[0052] When the heat exchanger (50) is installed under water, a
heat exchanger is performed by the same mechanism similar to that
of the foregoing embodiment.
Other Embodiments (Variations)
[0053] <1> The underground heat exchanger (50), i.e., the
outer pipe (51) of the foregoing embodiments may be inclinedly
installed under the ground or water. FIGS. 6(A) and 6(B) are views
schematically illustrating a state in which a heat exchanger (50)
is inclinedly installed. FIG. 6(A) illustrates an example in which
the heat exchanger (50) is inclinedly installed under the ground,
and FIG. 6(B) illustrate an example in which the heat exchanger
(50) is inclinedly installed under water. FIG. 6(B) illustrates the
example in which the heat exchanger (50) is inclinedly installed in
the sea, a lake, or a pond. Similarly, the heat exchanger (50) may
be inclinedly installed in, e.g., a water storage tank or a
pool.
[0054] <2> As illustrated in FIGS. 7(A) and 7(B), a wick (90)
may be provided on an inner wall surface of an outer pipe (51). A
liquid heat medium inside the outer pipe (51) penetrates the wick
(90), and is held by the wick (90). The wick (90) allows the held
liquid refrigerant to contact the inner wall surface of the outer
pipe (51). The wick (90) includes, e.g., an assembly of a porous
metal body, porous ceramic, and fibers. The wick (90) is provided
on the inner wall surface of the outer pipe (51) as described
above, thereby ensuring uniform moistening of the inner wall
surface of the outer pipe (51). Consequently, heat exchange
capability is improved in a heating operation.
[0055] <3> As illustrated in a cross-sectional view of FIG.
8, a plurality of grooves (100) may be provided in an inner wall
surface of an outer pipe (51). Specifically, the width, depth, and
number of the grooves (100) are set so that a liquid heat medium
inside the outer pipe (51) is held. A direction of the grooves
(100) is not limited to a direction parallel to an axial direction
of the outer pipe (51). For example, the grooves (100) may be
formed in a circumferential direction, or may be helically formed.
The grooves (100) are provided in the inner wall surface of the
outer pipe (51), thereby ensuring uniform moistening of the inner
wall surface of the outer pipe (51). Consequently, heat exchange
capability is improved in a heating operation.
INDUSTRIAL APPLICABILITY
[0056] The present invention is useful as the heat exchanger
installed under the ground or water, and the air conditioning
system using the heat exchanger.
DESCRIPTION OF REFERENCE CHARACTERS
[0057] 1 Air Conditioning System [0058] 50 Heat Exchanger [0059] 51
Outer Pipe [0060] 52 Heat Medium Guiding Section [0061] 80 Heating
Heat-Transfer Pipe [0062] 90 Wick [0063] 100 Groove
* * * * *