[0001] A double-pipe heat exchanger is disclosed herein.
[0002] Heat exchangers are known. However, they suffer from various disadvantages.
[0003] It is the object of the present invention to provide a heat exchanger having improved
characteristics. This object is solved with the features of the claims.
[0004] Embodiments will be described in detail with reference to the following drawings
in which like reference numerals refer to like elements, wherein:
[0005] Fig. 1 is a cross-sectional view of a double-pipe heat exchanger according to an
embodiment;
[0006] Fig. 2 is an enlarged view of portion A of Fig. 1; and
[0007] Fig. 3 is a graph showing a relationship between heat transfer performance and a
pitch W of a spiral part in a double-pipe heat exchanger according to an embodiment.
[0008] The advantages, features and aspects will become apparent from the following description
of the embodiments with reference to the accompanying drawings, which is set forth
hereinafter. The terms and words used in the description below are not limited to
typical or dictionary definitions, but can be interpreted with proper meanings and
definitions consistent with the technical ideas.
[0009] A heat exchanger is a device that transfers thermal energy from a high temperature
fluid to a relatively low temperature fluid, thereby cooling the high temperature
fluid and heating the low temperature fluid. The heat exchanger may be used in, for
example, a heater, a cooler, an evaporator, or a condenser.
[0010] A heat transfer medium used in the heat exchanger may be classified as a heating
medium that transfers heat to a subject or target fluid, and a cooling medium that
absorbs heat from the subject or target fluid. The cooling or heating medium may be
used in the gaseous or liquid state.
[0011] As one type of heat exchanger, a double-pipe heat exchanger may include an internal
tube into which a first fluid is introduced and flows, and an external tube disposed
so as to enclose the internal tube and into which a second fluid is introduced and
flows. A side wall of the internal tube may be used as a heat transfer wall that performs
heat exchange between the first and second fluids.
[0012] In such a double-pipe heat exchanger, a heat transfer surface area between the second
fluid and an outer wall of the internal tube may be small, and thus, heat exchange
efficiency very low. In order to enhance the heat exchange efficiency, a scale of
the heat exchanger or a length of the double pipe may be increased. However, it is
difficult to increase the scale of the heat exchanger or the length of the double
pipe due to problems of volume.
[0013] Fig. 1 is a cross-sectional view of a double-pipe heat exchanger according to an
embodiment, and Fig. 2 is an enlarged view of portion A of Fig. 1. Referring to Figs.
1 and 2, a double-pipe heat exchanger 300 according to this embodiment may include
a first heat exchange tube 100 and a second heat exchange tube 200.
[0014] The first heat exchange tube 100 may be formed in a pipe shape having a first hollow
portion 110. For example, the first heat exchange tube 100 may have a first diameter
D1.
[0015] The first heat exchange tube 100 may include a first fluid inlet port 120 that communicates
with the first heat exchange tube 100 and a first fluid outlet port 130 that communicates
with the first heat exchange tube 100. A first fluid may be introduced into and flow
through the first fluid inlet port 120, and may be discharged through the first fluid
outlet port 130 after heat exchange.
[0016] In this exemplary embodiment, for example, the first fluid which is introduced through
the first fluid inlet port 120 and is then discharged through the first fluid outlet
port 130 may be a single-phase fluid, for example, cooling water. Further, the first
fluid may have a first temperature.
[0017] The second heat exchange tube 200 may be disposed inside the first heat exchange
tube 100, so that the first and second heat exchange tubes 100 and 200 are coaxial.
For example, the second heat exchange tube 200 may have a second diameter D2 smaller
than the first diameter D1 of the first heat exchange tube 100, and thus, a gap G
may be formed between the first and second heat exchange tubes 100 and 200. The first
fluid may pass through the gap G between the first and second heat exchange tubes
100 and 200. In this exemplary embodiment, for example, the second diameter D2 of
the second heat exchange tube 200 may be about 19.05 mm.
[0018] The second heat exchange tube 200 disposed inside the first heat exchange tube 100
may have a spiral part 210. The spiral part 210 may be formed at a surface of the
second heat exchange tube 200 so as to be in the form of a screw, and the screw-shaped
spiral part 210 may have multiple ridges 212 and grooves 214.
[0019] The spiral part 210 may be formed at both inner and outer surfaces of the second
heat exchange tube 200. The ridges 212 and grooves 214 of the spiral part 210 may
be formed by, for example, a processing roller.
[0020] A second fluid inlet port 202, which may be cylindrical, may be formed at one end
of the second heat exchange tube 200, and a second fluid outlet port 204, which may
be cylindrical, may be formed at the other end thereof. A second fluid may be introduced
into and flow through the second fluid inlet port 202 and may be discharged through
the second fluid outlet port 204 after heat exchange.
[0021] In this exemplary embodiment, the second fluid provided in the second heat exchange
tube 200 may be a two-phase fluid. For example, the second fluid may be converted
from a liquid state to a gaseous state within the second heat exchange tube 200. Alternatively,
the second fluid provided in the second heat exchange tube 200 may be a single-phase
fluid.
[0022] In this exemplary embodiment, the second fluid may have a second temperature that
is different from the first temperature of the first fluid. The first temperature
of the first fluid may be higher than the second temperature of the second fluid.
Alternatively, the first temperature of the first fluid may be lower than the second
temperature of the second fluid.
[0023] A pitch W of the spiral part 210 of the second heat exchange tube 200 and a height
difference Hc between the ridges 212 and grooves 214 formed by the spiral part 210
have a great influence on the heat transfer performance of the first and second heat
exchange tubes 100 and 200. If the height difference Hc and the pitch W of the spiral
part 210 are not optimized, the heat transfer performance may be reduced or deteriorated.
[0024] Fig. 3 is a graph showing a relationship between heat transfer performance and a
pitch W of a spiral part in a double-pipe heat exchanger according to an embodiment.
The X axis of the graph in Fig. 3 designates the pitch W of the spiral part 210 and
the Y axis designates the heat transfer performance.
[0025] Referring to Fig. 3, as the pitch W of the spiral part 210 gradually increases, the
heat transfer performance of the double-pipe heat exchanger 300 in Fig. 1, in turn,
decreases. When the pitch W of the spiral part 210 is about 4∼10 mm, a heat transfer
characteristic of the double-pipe heat exchanger 300 is within an allowable range.
[0026] However, when the pitch W of the spiral part 210 of the second heat exchange tube
200 is less than about 4 mm, the heat transfer characteristic increases, but it is
difficult to manufacture and process the pitch W of the spiral part 210. When the
pitch W of the spiral part 210 of the second heat exchange tube 200 is larger than
about 10 mm, the heat transfer characteristic decreases. Therefore, the pitch W of
the spiral part 210 may be about 4∼10 mm in consideration of working and heat transfer
characteristics.
[0027] As shown in Fig. 2, the height difference Hc between the ridges 212 and grooves 214
of the spiral part 210 of the second heat transfer pipe 200 may be about 1∼3 mm. When
the height difference Hc between the ridges 212 and grooves 214 is less than about
1 mm, heat transfer efficiency decreases remarkably. When the height difference Hc
between the ridges 212 and grooves 214 is larger than about 3 mm, the heat transfer
efficiency increases, but it is difficult to manufacture and process the pitch W of
the spiral part 210. Therefore, the height difference Hc between the ridges 212 and
grooves 214 of the spiral part 210 may be about 1∼3 mm in order to satisfy working
and heat transfer characteristics.
[0028] In order to form the ridges 212 and grooves 214 of the spiral part 210 of the second
heat transfer pipe 200, a ratio A/W, which is a distance A between a half point W/2
of the pitch W and a top portion P of the ridge 212 divided by the pitch W may be
less than about 0.15. In this exemplary embodiment, if the second fluid, which is
converted from liquid phase to gaseous phase, is provided in the second heat exchange
tube 200, the second fluid may be rotated at a high speed by the spiral part 210 of
the second heat transfer tube 200. At this point, the liquid-phase second fluid having
a higher density than the gaseous-phase second fluid may be mainly distributed at
an inner side surface of the spiral part 210, and the gaseous-phase second fluid having
a relatively low density may be mostly distributed at a center portion of the spiral
part 210.
[0029] Accordingly, the liquid-phase second fluid and the gaseous-phase second fluid may
be separated from each other by a cyclone effect. The liquid-phase second fluid distributed
at the inner side surface of the spiral part 210 may be actively heat-exchanged with
the first fluid provided in the first heat exchange tube 100, and thus, the heat exchange
characteristics between the first and second fluids may be further improved.
[0030] According to embodiments disclosed herein, the spiral part may be formed on a surface
of the second heat exchange tube disposed inside the first heat exchange tube, and
the pitch and height of the spiral portion may be optimized, improving considerably
the heat transfer efficiency.
[0031] Embodiments disclosed herein provide a double-pipe heat exchanger in which a heat
exchange tube disposed at a relatively inner side may be formed in a spiral shape
in which ridges and grooves may be continuously formed, thereby increasing a heat
transfer performance.
[0032] Further, embodiments disclosed herein provide a double-pipe heat exchanger that may
include a first heat exchange tube having a first hollow portion, and a second heat
exchange tube disposed inside the first heat exchange tube so as to be co-axial with
the first heat exchange tube and having a spiral part in which multiple ridges and
grooves may be formed at an inner surface of the spiral part.
[0033] The second heat exchange tube may include a cylindrical second fluid inlet port,
which may be inserted into or provided at one side of the first heat exchange tube
and through which a second fluid may pass; a cylindrical second fluid outlet port,
which may be inserted into or provided at the other side of the first heat exchange
tube and through which the second fluid may be discharged; and a screw-shaped spiral
part continuously formed between the second fluid inlet port and the second fluid
outlet port.
[0034] A ratio A/W of a pitch W that is a length between adjacent grooves of the second
heat exchange tube to a distance A between a center portion of the pitch W and a top
portion P of the ridge may be less than about approximately 0.15.
[0035] The pitch W may be approximately 4 mm<W<10 mm, and a height difference Hc between
the adjacent ridges and grooves may be approximately 1 mm<Hc<3 mm.
[0036] A temperature of a first fluid provided between the first and second heat exchange
tubes may be different from that of a second fluid provided in the second heat exchange
tube. The second fluid provided in the second heat exchange tube may be one of a single-phase
fluid or a two-phase fluid.
[0037] Any reference in this specification to "one embodiment," "an embodiment," "example
embodiment," etc., means that a particular feature, structure, or characteristic described
in connection with the embodiment is included in at least one embodiment of the invention.
The appearances of such phrases in various places in the specification are not necessarily
all referring to the same embodiment. Further, when a particular feature, structure,
or characteristic is described in connection with any embodiment, it is submitted
that it is within the purview of one skilled in the art to effect such feature, structure,
or characteristic in connection with other ones of the embodiments.
[0038] Although embodiments have been described with reference to a number of illustrative
embodiments thereof, it should be understood that numerous other modifications and
embodiments can be devised by those skilled in the art that will fall within the spirit
and scope of the principles of this disclosure. More particularly, various variations
and modifications are possible in the component parts and/or arrangements of the subject
combination arrangement within the scope of the disclosure, the drawings and the appended
claims. In addition to variations and modifications in the component parts and/or
arrangements, alternative uses will also be apparent to those skilled in the art.
1. A double-pipe heat exchanger,
characterized by:
a first heat exchange tube having a first hollow portion; and
a second heat exchange tube disposed inside the first heat exchange tube and having
a spiral part in which multiple ridges and grooves are formed at an inner surface
thereof.
2. The double-pipe heat exchanger of claim 1, characterized in that the second heat exchange tube is disposed inside the heat exchange tube so as to
be coaxial with the first heat exchange tube.
3. The double-pipe heat exchanger of claim 1 or 2,
characterized in that the first heat exchange tube comprises:
a first fluid inlet port through which a first fluid is introduced into the first
heat exchange tube; and
a first fluid outlet port through which the first fluid is discharged from the first
heat exchange tube.
4. The double-pipe heat exchanger of any of claims 1 to 3,
characterized in that the second heat exchange tube comprises:
a second fluid inlet port through which a second fluid is introduced into the second
heat exchange tube;
a second fluid outlet port through which the second fluid is discharged from the second
heat exchange tube; and
the spiral part which extends between the second fluid inlet port and the second fluid
outlet port.
5. The double-pipe heat exchanger of claim 4, characterized in that the second fluid inlet port extends through a first side wall of the first heat exchange
tube, and the second fluid outlet port extends through a second side wall of the heat
exchange tube.
6. The double-pipe heat exchanger of claim 5, characterized in that the second side wall is opposite the first side wall.
7. The double-pipe heat exchanger of any of claims 4 to 6, characterized in that the second fluid inlet pipe and second fluid outlet pipe are cylindrical.
8. The double-pipe heat exchanger of any of claims 1 to 7, characterized in that a ratio A/W of a pitch W, which is a length between adjacent grooves of the second
heat exchange tube, to a distance A between a center portion of the pitch W and a
top portion P of the ridge is less than about 0.15.
9. The double-pipe heat exchanger of any of claims 1 to 8, characterized in that the pitch W is approximately 4 mm<W<10 mm, and a height difference Hc between an
adjacent ridge and groove is approximately 1 mm<Hc<3 mm.
10. The double-pipe heat exchanger of any of claims 1 to 9, characterized in that a temperature of a first fluid provided between the first and second heat exchange
tubes is different from a temperature of a second fluid provided in the second heat
exchange tube.
11. The double-pipe heat exchanger of any of claims 4 to 10, characterized in that the second fluid is one of a single-phase fluid or a two-phase fluid.
12. A double-pipe heat exchanger,
characterized by:
a first heat exchange tube having a first hollow portion; and
a second heat exchange tube disposed inside the first heat exchange tube so as to
be coaxial with the first heat exchange tube and having a spiral part in which multiple
ridges and grooves are formed at an inner surface thereof, wherein the second heat
exchange tube comprises:
a second fluid inlet port the second heat exchange tube through which a second fluid
is introduced into the second heat exchange tube;
a second fluid outlet port through which the second fluid is discharged from the second
heat exchange tube; and
the spiral part which extends between the second fluid inlet port and the second fluid
outlet port.
13. The double-pipe heat exchanger of claim 12, characterized in that the second fluid inlet port extends through a first side wall of the first heat exchange
tube, and the second fluid outlet port extends through a second side wall of the heat
exchange tube.
14. A double-pipe heat exchanger,
characterized by:
a first heat exchange tube having a first hollow portion; and
a second heat exchange tube disposed inside the first heat exchange tube so as to
be coaxial with the first heat exchange tube and having a spiral part in which multiple
ridges and grooves are formed at an inner surface thereof, wherein the pitch W, which
is a length between adjacent grooves of the second heat exchange tube, is approximately
4 mm<W<10 mm, and a height difference Hc between an adjacent ridge and groove is approximately
1 mm<Hc<3 mm.