Patent Application
20130112380
The present invention relates to a heat exchanger including left and right headers and heat transfer tubes provided between the headers, and more specifically, it relates to a heat exchanger with improved heat exchange efficiency achieved by making fluid flow over a radially outside of the heat transfer tubes along the axial direction.
Conventionally, various heat exchangers using multi-layer tubes have been proposed.
Furthermore, another heat exchanger using multi-layer tubes and having the structure shown in
However, when heat exchange is performed using such multi-layer tubes, the following problem occurs: that is, in the heat exchangers illustrated in
Hence, the present invention has been made to overcome the above-described problem, and an object thereof is to provide a heat exchanger that performs heat exchange using multi-layer tubes and can perform efficient heat exchange, even when a high flow rate is to be ensured.
More specifically, the present invention has been made to overcome the above-described problem, and it provides a heat exchanger using heat transfer tubes each including an outer tube and an inner tube, the heat exchanger performing heat exchange between first fluid flowing through a gap between the outer tube and the inner tube and second fluid flowing through the inner tube. The heat exchanger includes header units that direct the first fluid through the gaps between the inner tubes and the outer tubes from the outer circumferences of the inner tubes, the ends of the inner tubes extending from the outer tubes; second headers that direct second fluid through the inner tubes extending from the header units; and gap portions provided between the stacked header units, through which the second fluid from the second headers flows. The second fluid from the second headers is directed through the inside of the inner tubes and over outer surfaces of the outer tubes along the axial direction via the gap portions.
More specifically, the heat exchanger includes header units each holding portions near ends of the outer tubes at a first wall and allowing the inner tubes, which extend from the outer tubes, to extend through a second wall facing the first wall, the header units directing the first fluid through the gaps between the inner tubes and the outer tubes from a space enclosed by the first wall and the second wall; second headers that direct the second fluid through the inner tubes extending from the second walls of the header units; and gap portions provided between the stacked header units, through which the second fluid from the second headers flows. The second fluid from the second headers is directed through the inside of the inner tubes and over outer surfaces of the outer tubes along the axial direction via the gap portions.
With this configuration, the first fluid flowing through the gaps between the outer tubes and the inner tubes can be cooled or heated by the second fluid from both inside and outside. Thus, the heat exchange efficiency can be improved.
Furthermore, in this invention, the gap portions are provided by disposing gap-forming members between the stacked header units.
With this configuration, a change in size of the gap portions can be achieved by changing the thickness of the gap-forming members. Thus, gaps of an appropriate size can be easily provided.
Alternatively, projections or recesses are formed as an integral part of the header units, and the gap portions are provided utilizing the spaces between the projections and the recesses.
With this configuration, the gap portions can be provided only by staking the header units having the projections or recesses. Thus, bonding the gap-forming members in an assembly process is eliminated.
Moreover, splitting members extending along the axial direction of the heat transfer tubes are provided between upper and lower heat transfer tubes of the stacked header units.
With this configuration, the second fluid flowing via the gap portions can be split and directed toward the surfaces of the heat transfer tubes via the splitting members. Thus, the second fluid can be directed near the surfaces of the heat transfer tubes, thereby improving the heat exchange efficiency.
Furthermore, the splitting members are provided in contact with the heat transfer tubes of the stacked header units, and the second fluid flowing from the gap portions is split and directed toward the heat transfer tubes.
With this configuration, the gap portions may be formed by disposing the splitting members between the heat transfer tubes of the header units, and thermal diffusion can also be performed by making the splitting members in contact with the heat transfer tubes.
The present invention provides a heat exchanger using heat transfer tubes each including an outer tube and an inner tube, the heat exchanger performing heat exchange between first fluid flowing through a gap between the outer tube and the inner tube and second fluid flowing through the inner tube, the heat exchanger including header units that direct the first fluid through the gaps between the inner tubes and the outer tubes from the outer circumferences of the inner tubes, the ends of the inner tubes extending from the outer tubes; second headers that direct second fluid through the inner tubes extending from the header units; and gap portions provided between the stacked header units, through which the second fluid from the second headers flows. The second fluid from the second headers is directed through the inside of the inner tubes and over outer surfaces of the outer tubes along the axial direction via the gap portions. Thus, the first fluid flowing through the gaps between the outer tubes and the inner tubes can be cooled or heated by the second fluid from both inside and outside, and the heat exchange efficiency can be improved.
An embodiment of the present invention will be described below with reference to the drawings. As illustrated in
The structure of the first headers 2a constituting this heat exchanger 1 will be described. The first headers 2a are each formed by stacking the header units 21 holding the heat transfer tubes 4, each including the inner tubes 41 and the outer tube 42. As illustrated in
Next, the structure of the second headers 2b will be described. The second headers 2b are configured to direct the second fluid through the inner tubes 41 extending from the second recesses 28b, and in this embodiment, the second headers 2b are formed of a single header cover 3b that covers the first headers 2a and the header covers 3a. In this embodiment, the header cover 3b has a case-like structure that completely covers the first headers 2a on the left and right sides and the heat transfer tubes 4 therebetween, and the second fluid is introduced from an inlet port 31b and discharged from an outlet port 32b (see
In each heat transfer tube 4, two inner tubes 41 are internally in contact with the outer tube 42 such that their axial planes are aligned. With this configuration, even when the inner tubes 41 expand due to an increase in pressure, the inner tubes 41 internally come into contact with the inner surface of the outer tube 42, and the expansion of the inner tubes 41 can be prevented. When such heat transfer tubes 4 are to be formed, in order to improve the heat exchange efficiency, for example, the outside diameter of the outer tubes 42 is set from about 0.8 mm to 2.0 mm, and more preferably, from about 0.9 mm to 1.5 mm, and the inside diameter thereof is set from about 0.7 mm to 1.9 mm, and more preferably, from about 0.8 mm to 1.4 mm.
Furthermore, splitting members 9 are attached to the upper and lower heat transfer tubes 4 of the header units 21 arranged in a stack. The splitting members 9 are provided in contact with the outer circumferences of the heat transfer tubes 4, so that the second fluid flowing through the gap portions W is split and directed toward the outer circumferences of the heat transfer tubes 4. That is, without the splitting members 9, the second fluid flowing through the gap portions W flows through the gap spaces where no heat transfer tubes 4 are provided, which decreases the heat exchange efficiency. Hence, the splitting members 9 are provided in the gap spaces where heat exchange does not need to be performed, thereby directing the second fluid toward the heat transfer tubes 4 to disperse the heat from the heat transfer tubes 4 and improving the heat exchange efficiency. When the splitting members 9 are attached in this manner, as illustrated in
Next, advantages obtained when the thus-configured heat exchanger 1 is used will be described.
First, when the first fluid is introduced from the inlet port 31a in the first header 2a, the first fluid flows via the header cover 3a into the header units 21, from which the first fluid is split and flows along the spaces between the outer tubes 42 and the inner tubes 41.
Furthermore, at the same time, the second fluid is introduced from the inlet port 31b in the second header 2b. The second fluid then flows from the space enclosed by the header cover 3b into the inner tubes 41 and flows along the axial direction of the inner tubes 41. Furthermore, the second fluid not flowing into the inner tubes 41 flows in the axial direction of the heat transfer tubes 4 via the gap portions W between the header units 21. Then, the second fluid is split by the splitting members 9 provided in the gaps between the heat transfer tubes 4 and directed toward the upper and lower heat transfer tubes 4, and the second fluid in contact with the outer surfaces of the heat transfer tubes 4 cools or heats the first fluid.
As described above, in this embodiment, the header units 21 are stacked with the predetermined gap portions W therebetween, and the second fluid is made to flow along the axial direction of the heat transfer tubes 4 from the gap portions W. Thus, heat exchange can be performed over the entire heat transfer tubes 4.
Furthermore, because the splitting members 9 in contact with the surfaces of the heat transfer tubes 4 are provided along the axial direction in this embodiment, it is possible to direct the second fluid flowing from the gap portions W toward the surfaces of the heat transfer tubes 4 to further improve the heat exchange efficiency.
Next, a second embodiment of the present invention will be described. In the above-described first embodiment, the gap portions W are provided using the gap-forming members 8. In the second embodiment, as illustrated in
The unit segments 22 constituting the header units 21 according to this embodiment have projections 25a standing upright from the lower side of the bottom surface so as to have a certain thickness, and recesses 25b between the projections 25a, thereby forming the gap portions W. Herein, the projections 25a are formed as an integral part of the unit segments 22 when the unit segments 22 are produced. As illustrated in
Alternatively, as illustrated in
As described above, in the second embodiment, because the projections 25a (or the recesses 25b) are formed as an integral part of the header units 21, there is no need to attach the gap-forming members 8 when the header units 21 are stacked. Thus, the task in a stacking process can be simplified.
Although the recesses 25b are formed between the projections 25a by forming the projections 25a in this embodiment, conversely, the recesses 25b may be formed by removing the bottom surface portion of the unit segment 22, so that the projections 25a are formed between the recesses 25b.
Next, a third embodiment will be described. Although the gap portions W are provided by the gap-forming members 8 or the projections 25a in the above-described first and second embodiments, in this embodiment, as illustrated in
The heat exchanger 1 according to this embodiment is configured without the gap-forming members 8 illustrated in
The splitting members 9, which are formed of metallic members having a high thermal conductivity, are in contact with the surfaces of the heat transfer tubes 4 to disperse the heat of the heat transfer tubes 4 and to split and direct the second fluid flowing from the gap portions W toward the heat transfer tubes 4 to be subjected to heat exchange.
Note that, when the splitting members 9 are formed of metallic rigid members, the gap between the upper and lower header units 21 is determined by the thickness of the splitting members 9, and if the heat transfer tubes 4 are deformed or when the thickness of the splitting members 9 is inaccurate, the width of the gap between the header units 21 changes. When the gap width changes, the positions of the openings 27 in the header unit 21 change, making it difficult to attach the header covers 3a thereto. Hence, the splitting members 9 may be formed of, for example, metallic elastic structures, or, only upper and lower surfaces may be formed of metallic members and a layer therebetween may be formed of an elastic material that is relatively elastic, such as urethane. With this configuration, the deformation of the heat transfer tubes 4 may be absorbed owing to the elasticity, making it easy to position the header covers 3a with respect to the openings 27 when the header covers 3a are attached to the openings 27.
Note that the present invention is not limited to the above-described embodiments, but may be embodied in various other forms.
For example, although the splitting members 9 are configured to be parallel to the stacked header units 21 and are disposed between the heat transfer tubes 4 in the above-described embodiments, when a high heat exchange rate can be ensured without the splitting members 9, the splitting members 9 do not have to be attached.
Furthermore, although two inner tubes 41 are provided in a circular outer tube 42 in the above-described embodiments, the outer tube may have any shape, and the number of inner tubes may be any value. That is, any shape and any number may be employed, as long as the first fluid is subjected to heat exchange from both inside and outside.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2010-158342 | Jul 2010 | JP | national |
| Filing Document | Filing Date | Country | Kind | 371c Date |
|---|---|---|---|---|
| PCT/JP2011/065537 | 7/7/2011 | WO | 00 | 1/14/2013 |
