Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the drawings are not to precise scale and may be exaggerated in thicknesses of lines or sizes of components for descriptive convenience and clarity only. In addition, the terms used herein are defined by taking functions of the present invention into account and can be changed according to user or operator custom or intention. Therefore, definition of the terms should be made according to the overall disclosure set forth herein.
FIG. l is a perspective view of a double tube for heat exchange according to one embodiment of the present invention, and FIG. 2 is an exploded perspective view of the double tube for heat exchange according to one embodiment of the present invention.
FIG. 3 is a sectional view taken along A-A line of FIG. l, FIG. 4 is an enlarged view of a main section of FIG. 3, and FIG. 5 is a sectional view taken along B-B line of FIG. l.
FIG. 6 is a plan view of a flattened portion according to one embodiment of the present invention.
FIG. 7 is an enlarged view of a main section of FIG. 3 showing the state after crimping.
Referring to Figs. l to 7, a double tube for heat exchange 100 according to one embodiment of the present invention includes inner pipes 112, 114, a spiral pipe 120, pipe expansion joints 132, 134, and an outer pipe 140.
The double tube for heat exchange 100 according to the present invention allows heat exchange between a refrigerant (first fluid) at an outlet of an evaporator of an automotive air conditioner and a refrigerant (second fluid) at an outlet of a condenser of the air conditioner to reduce load of the compressor through increase in temperature of the first fluid introduced into a compressor, while improving vaporization efficiency through decrease in temperature of the second fluid introduced into an expansion valve.
Particularly, the outer pipe 140 has a tubular shape and allows a high-temperature and high-pressure fluid (the second fluid) at the outlet of the condenser to flow therethrough.
The inner pipes 112, 114 have a tubular shape, allow a low-temperature and low-pressure fluid (the first fluid) at the outlet of the evaporator to ow therethrough, and are inserted into the outer pipe 140.
Thus, the second fluid at high temperature and high pressure at the outlet of the condenser flows through a space between the inner pipes 112, 114 and the outer pipe 140.
That is, the double tube for heat exchange 100 according to the present invention allows heat exchange between the first fluid at low temperature and low pressure at the outlet of the evaporator and the second fluid at high temperature and high pressure at the outlet of the condenser through the inner pipes 112, 114.
In addition, the spiral pipe 120 connects the inner pipes 112, 114 to each other and is formed on a circumferential surface thereof with ridges 122 and valleys 124 in an alternating manner along a spiral track thereof.
Further, the spiral pipe 120 is connected at opposite sides thereof to the inner pipes 112, 114. In other words, a first inner pipe 112 is connected to one side of the spiral pipe 120 and the second inner pipe 114 is connected to the other side of the spiral pipe 120. It should be understood that the spiral pipe 120 may be formed at a portion of the first inner pipe 112 or a portion of the second inner pipe 114. Thus, the first fluid flows through the first inner pipe 112, the spiral pipe 120, and the second inner pipe 114.
Particularly, the spiral pipe 120 is formed with the ridges 122 and the valleys 124 in an alternating manner. Since the second fluid flows along the valleys 124 of the circumferential surface of the spiral pipe 120, residence time of the second fluid in the outer pipe 140 and the spiral pipe 120 is increased, thereby improving heat exchange efficiency between the second fluid and the first fluid.
In addition, the ridges 122 of the spiral pipe 120 may consecutively adjoin an inner surface of the outer pipe 140. As a result, the second fluid is allowed to flow along the valleys 124 of the spiral pipe 120.
For example, the entire portion of each of the ridges 122 may contact with the inner surface of the outer pipe 140, which results in no gap between the ridges 122 and the inner surface of the outer pipe 140. Accordingly, in this case, the second fluid is allowed to flow only through the valleys 124 of the spiral pipe 120, i.e., the second fluid cannot flow through between the ridges 122 and the inner surface of the outer pipe 140.
Due to such a contact state of the ridges 122 and the inner surface of the outer pipe 140, residence time of the second fluid can be increased. Further, when the double tube for heat exchange 100 is bent for a certain purpose, bending of the double tube for heat exchange 100 becomes easier since the outer pipe 140 and the spiral pipe 120 are bent together as if they are integrally formed. The ridges 122 may still be in contact with the inner surface of the outer pipe 140 even after the bending is completed.
The contact state of the ridges 122 and the inner surface of the outer pipe 140 can be obtained by using a suitable press machine, e.g. a press molding. For example, the outer pipe 140 may be pressed inward by the press machine. Specifically, a circumferential surface of the outer pipe 140 may be pressed onto the circumferential surface of the spiral pipe 120. Due to this pressing, the outer pipe 140 may be deformed, e.g. plastic deformed. The spiral pipe 120 may also be deformed, e.g. plastic deformed, as the outer pipe 140 is pressed.
More specifically, before pressing, an initial inner diameter of the outer pipe 140 may be greater than an initial outer diameter of the spiral pipe 120 (the vertical distance between portions of the circumferential surface of the spiral pipe 120 corresponding to ridges on a side in a circumferential direction and the other portions of the circumferential surface of the spiral pipe 120 corresponding to the other ridges on the opposite side in the circumferential direction) such that a gap between the ridges 122 and the inner surface of the outer pipe 140 may be present. As the outer pipe 140 is pressed and the spiral pipe 120 is also pressed accordingly, the inner diameter of the outer pipe 140 and the outer diameter of the spiral pipe 120 may decrease, and then a final inner diameter of the outer pipe 140 and a final outer diameter of the spiral pipe 120 may become equal to each other. In this final state of pressing, the final inner diameter of the outer pipe 140 may be less than the initial outer diameter of the spiral pipe 120.
The pipe expansion joints 132, 134 are placed at junctions between the inner pipes 112, 114 and the spiral pipe 120, respectively. The pipe expansion joints 132, 134 are sealed against a circumferential surface of the corresponding pipe of the inner pipes 112, 114 and are provided with ports 133, 135 for inflow/outflow of the second fluid, respectively.
In other words, a first pipe expansion joint 132 covers a junction between the first inner pipe 112 and the spiral pipe 120, and a second pipe expansion joint 134 covers a junction between the second inner pipe 114 and the spiral pipe 120.
The first pipe expansion joint 132 is sealed along a circumferential surface of the rst inner pipe 112 by brazing, welding and the like. The second pipe expansion joint 134 is sealed along a circumferential surface of the second inner pipe 114 by brazing, welding and the like.
Further, before the first pipe expansion joint 132 is sealed against the first inner pipe 112, a first part of an end portion of the first pipe expansion joint 132 may be crimped upon the first inner pipe 112 by a suitable press machine such that a portion of the first inner pipe 112 corresponding to the first part may be deformed (e.g. plastic deformed) inward, and therefore a diameter of the first inner pipe 112 may decrease in said portion. In addition, the first part may be bent inward while being in contact with the circumferential surface of the first inner pipe 112 as the first part is crimped, thus the first pipe expansion joint 132 and the first inner pipe 112 may be fixed to each other.
Here, the aforementioned first part may refer to a specific region of a circumferential surface of the end portion of the first pipe expansion joint 132 that extends in the circumferential direction.
Furthermore, a second part of the end portion of the first pipe expansion joint 132, which is positioned farther from the spiral pipe 120 than the first part, may be bent outward as the first part is crimped such that a gap 170 may be formed between the second part and the first inner pipe 112. The gap 170 may be filled with a coupling material configured to couple the second part to the first inner pipe 112. For example, if the second part and the first inner pipe 112 are coupled to each other by means of brazing, welding and the like, the coupling material could be a brazing material, a welding material, a soldering material and the like.
Similar to the first pipe expansion joint 132, before the second pipe expansion joint 134 is sealed against the second inner pipe 114, a first part of an end portion of the second pipe expansion joint 134 may be crimped upon the second inner pipe 114 by a suitable press machine such that a portion of the second inner pipe 114 corresponding to the first part may be deformed (e.g. plastic deformed) inward, and therefore a diameter of the second inner pipe 114 may decrease in said portion. In addition, the first part may be bent inward while being in contact with the circumferential surface of the second inner pipe 114 as the first part is crimped, thus the second pipe expansion joint 134 and the second inner pipe 114 may be fixed to each other.
Here, the aforementioned first part may refer to a specific region of a circumferential surface of the end portion of the second pipe expansion joint 134 that extends in the circumferential direction.
Furthermore, a second part of the end portion of the second pipe expansion joint 134, which is positioned farther from the spiral pipe 120 than the first part, may be bent outward as the first part is crimped such that a gap 170 may be formed between the second part and the second inner pipe 114. The gap 170 may be filled with a coupling material configured to couple the second part to the second inner pipe 114. For example, if the second part and the second inner pipe 114 are coupled to each other by means of brazing, welding and the like, the coupling material could be a brazing material, a welding material, a soldering material and the like.
Since the portion of each of the inner pipes 112, 114 corresponding to the first part may be deformed inward and the first part may be bent inward while being in contact with the circumferential surface of each of the inner pipes 112, 114 as the first part is crimped, as described above, fixation between the pipe expansion joints 132, 134 and the inner pipes 112, 114 could be improved.
In addition, since the second part may be automatically bent outward as the first part is crimped and the gap 170 may be formed accordingly, coupling of the pipe expansion joints 132, 134 and the inner pipes 112, 114 could easily be performed by filling the gap 170 with the coupling material. In other words, there is no need to further make the end portions of the pipe expansion joints 132, 134 tapered, i.e. have a varying thickness in the axial direction which becomes thinner as distance from the spiral pipe 120 increases, so as to forming the gap 170. In this embodiment, each of the end portions of the pipe expansion joints 132, 134 may be cut off straight and may have a uniform thickness in the axial direction.
The first pipe expansion joint 132 and the second pipe expansion joint 134 are connected to the outer pipe 140. Here, the outer pipe 140 may be integrally formed with the first pipe expansion joint 132 at one side thereof and be integrally formed with the second pipe expansion joint 134 at the other side thereof.
It should be understood that the first pipe expansion joint 132 and the second pipe expansion joint 134 may also be connected to the outer pipe 140 by welding and the like.
As such, the outer pipe 140 is configured to surround the entire spiral pipe 120.
In addition, the first pipe expansion joint 132 has a first port 133 for receiving the second fluid at high temperature and high pressure from the outlet of the condenser, and the second pipe expansion joint 134 has a second port 135 for discharging the heat exchanged second fluid to the expansion valve.
Thus, the second fluid introduced through the first port 133 flows along the valleys 124 in a space between the outer pipe 140 and the spiral pipe 120 and is then discharged through the second port 135.
Here, the second fluid exchanges heat with the first fluid that flows along the first inner pipe 112, the spiral pipe 120, and the second inner pipe 114. That is, the first fluid is heated through heat exchange with the second fluid, and the second fluid is cooled through heat exchange with the first fluid.
Thus, the inner pipes 112, 114, the spiral pipe 120, and the outer pipe 140 may be formed of a material having high thermal conductivity.
The first pipe expansion joint 132 and the second pipe expansion joint 134 have the same shape to be interchangeable with each other. Here, each of the first pipe expansion joint 132 and the second pipe expansion joint 134 includes a pipe expansion portion 137, a packing member 138, and a connection member 139. The packing member 138 may correspond to the end portions of the pipe expansion joints 132, 134 discussed above.
The pipe expansion portion 137 has a greater diameter than the outer pipe 140 so as to reduce flow noise of the second fluid. Here, the pipe expansion portions 137 are configured to surround a junction between the first inner pipe 112 and the spiral pipe 120 and a junction between the second inner pipe 114 and the spiral pipe 120, respectively. It should be understood that the pipe expansion portions 137 may also be placed at both sides in an axial direction of the spiral pipe 120.
In addition, the pipe expansion portion 137 has a greater diameter than the outer pipe 140.
That is, a space between the pipe expansion portion 137 and the spiral pipe 120 is expanded, whereby the transfer pressure and transfer rate of the second fluid can be reduced when the second fluid is introduced through the first port 133 of the pipe expansion portion 137, thereby reducing flow-induced noise.
In addition, since the space between the pipe expansion portion 137 and the spiral pipe 120 is expanded, transient storage capacity for the second fluid is increased just before the second fluid is discharged through the second port 135 of the pipe expansion portion 137, thereby stably securing a sufficient discharge amount.
The packing member 138 may be connected to the circumferential surface of the corresponding pipe of the first inner pipe 112 and the second inner pipe 114 to be packed.
The packing member 138 may have a first part 138a and a second part 138b as shown in Fig. 4. The second part 138b may be positioned farther from the spiral pipe 120 than the first part 138a.
Referring to Fig. 7, the first part 138a of the packing member 138 of each of the pipe expansion joints 132, 134 may be crimped upon the inner pipes 112, 114, in the direction of the illustrated arrows, by a suitable press machine such that a portion 112a, 114a of each of the inner pipes 112, 114 corresponding to the first part 138a may be deformed (e.g. plastic deformed) inward, and therefore a diameter of each of the inner pipes 112, 114 may decrease in said portion 112a, 114a. In addition, the first part 138a may be bent inward while being in contact with the circumferential surface of each of the inner pipes 112, 114 as the first part 138a is crimped, thus the pipe expansion joints 132, 134 and the inner pipes 112, 114 may be fixed to each other.
Here, the aforementioned first part 138a may refer to a specific region of a circumferential surface of the packing member 138 of the pipe expansion joints 132, 134 that extends in the circumferential direction.
The second part 138b of the packing member 138 of each of the pipe expansion joints 132, 134 may be bent outward as the first part 138a is crimped such that a gap 170 may be formed between the second part 138b and each of the inner pipes 112, 114. The gap 170 may be filled with a coupling material configured to couple the second part 138b to the inner pipes 112, 114. For example, if the second part 138b and each of the inner pipes 112, 114 are coupled to each other by means of brazing, welding and the like, the coupling material could be a brazing material, a welding material, a soldering material and the like.
The packing member 138 may be cut off straight at the one end, the left-end when referring to Fig. 4, and may have a uniform thickness in the axial direction even after crimping of the first part 138a.
Further, the packing member 138 may also have a third part 138c which is positioned closer to the spiral pipe 120 than the first part 138a and is tapered, i.e. inclined towards the inner pipes 112, 114 from one side of the pipe expansion portion 137 as shown in Fig. 4. Particularly, since the packing member 138 has the tapered third part 138c inclined towards the inner pipes 112, 114 from the pipe expansion portion 137, flow resistance of the second fluid can be reduced, thereby reducing flow-induced noise.
Moreover, the connection member 139 may have a tapered part inclined towards the spiral pipe 120 from the other side of the pipe expansion portion 137 as shown in Fig. 4. In addition, the connection member 139 is connected to the outer pipe 140. Here, the connection member 139 is sealed at an edge thereof against a corresponding edge of the outer pipe 140 by welding and the like. Since the connection member 139 has the tapered part inclined towards the spiral pipe 120 from the pipe expansion portion 137, flow resistance of the second fluid can be reduced, thereby reducing flow-induced noise.
As described above, the second fluid stably flows along the valleys 124 in a particular direction. In order to allow the second fluid to flow more stably, each of the valleys 124 is provided with at least one groove 126 along a spiral track of the valley 124.
Particularly, a plurality of grooves 126 is formed to be parallel to one another in order to improve flow directionality of the second fluid while increasing a contact area between the second fluid and the spiral pipe 120.
Here, the groove 126 is not particularly limited in terms of shape, number, and height.
By a flattening process, each of the pipe expansion joints 132, 134 may be formed with a attened portion 150 at a portion of the curved circumferential surface thereof at which the corresponding pipe of the first port 133 and the second port 135 is formed.
The flattened portion 150 is formed by flattening the circumferential surfaces of the pipe expansion joints 132, 134 along the peripheries of the first port 133 and the second port 135 such that the first port 133 and the second port 135 can be easily coupled to the pipe expansion joints 132, 134, respectively, by welding and the like.
In other words, the first port 133 and the second port 135 may be partially inserted into the corresponding pipe of the pipe expansion joints 132, 134 and then welded by two-dimensionally moving a welding jig (not shown) on the flattened portion 150, thereby allowing easy welding while preventing welding defects.
By providing the flattened portion 150, a space expansion portion 152 can be naturally created inside the pipe expansion portion 137. It should be understood that the space expansion portion 152 may also be separately formed in an inner surface of each of the pipe expansion joints 132, 134.
The space expansion portion 152 can further reduce flow resistance of the second fluid, thus reducing flow-induced noise. It should be understood that the flattened portion 150 may be machined using various jigs.
Heat exchange performance can be controlled by increasing/reducing the pitch between adjacent valleys 124 or between adjacent ridges 122 of the spiral pipe 120.
Particularly, as the number of grooves 126 of the valley 124 is increased, the distance between adjacent ridges 122 in the axial direction of the outer pipe 140 increases, thereby reducing flow-induced noise.
As the distance between adjacent ridges 122 is increased, noise reduction is further improved. However, this increased distance between adjacent ridges 122 can cause an increased pressure loss in a flow path of the second fluid or re-expansion of the second fluid when the second fluid, which is at high temperature and high pressure, flows through the valleys 124. Thus, it is necessary to appropriately adjust a ratio of a sectional area of a flow path for the second fluid to the distance between adjacent ridges 122.
In addition, a resistance member 160 may protrude from the valley 124. The resistance member 160 protrudes between adjacent ridges 122 and is not limited in terms of shape and number.
The resistance member 160 serves to increase the residence time of the second fluid in the valleys 124 while supporting the ridges 122 adjacent thereto.
It should be understood that the distance of adjacent resistance members 160 is not particularly limited.
Here, the spiral pipe 120 is formed with the grooves 126 along the spiral track thereof in a discontinuous manner such that the resistance members 160 can be naturally formed. Particularly, the resistance member 160 needs to have a smaller height than the ridge portion 122 to allow flow of the second fluid.
Thus, the resistance member 160 may be partially chamfered at an upper portion thereof. It should be understood that the resistance member 160 may be formed in various shapes.
According to the present invention, the double tube for heat exchange includes the spiral pipe axially inserted into the outer pipe to increase residence time of the second fluid inside the outer pipe, thereby improving heat exchange efficiency between the first fluid flowing through the spiral pipe and the second fluid flowing between the outer pipe and the spiral pipe.
In addition, according to the present invention, the double tube for heat exchange includes at least one groove formed on the circumferential surface of the spiral pipe along the spiral track of the valleys to improve flow directionality of the second fluid so as to allow the second fluid to flow more stably, thereby further improving heat exchange efficiency.
Further, according to the present invention, the double tube for heat exchange has pipe expansion joints, which are having increased diameters and connected to the ends of the outer pipe, to expand a space between the outer pipe and the inner pipe so as to reduce pressure of a fluid during inflow and outflow of the fluid, thereby reducing flow-induced noise.
Furthermore, according to the present invention, the double tube for heat exchange can prevent excessive warpage of the ridges of the spiral pipe through the resistance member adjacent to the ridges, thus durability of the spiral pipe can be improved.
Although some embodiments have been described herein, it should be understood that these embodiments are provided for illustration only and are not to be construed in any way as limiting the present invention, and that various modifications, changes, and alterations can be made by those skilled in the art without departing from the spirit and scope of the invention. Therefore, the scope of the present invention should be defined by the appended claims and equivalents thereof.