JP4414198B2 - Double tube heat exchanger - Google Patents

Description

  The present invention relates to a double-pipe heat exchanger that performs heat exchange between a fluid that flows through an inner pipe and a fluid that flows through an outer pipe provided outside the inner pipe.

  Conventionally, in a heat pump type hot water heater, an air conditioner, a floor heater, and the like, a double pipe type heat exchanger is used in order to exchange heat between a refrigerant such as carbon dioxide and chlorofluorocarbon and water.

  This type of double-pipe heat exchanger has an inner pipe in which a refrigerant flow path is formed inside and an outer pipe that is provided outside the inner pipe and in which a water flow path is formed between the inner pipe and the inner pipe. A double pipe having a pipe is provided, and the double pipe is usually formed in a spiral shape. Then, the end of the inner pipe is connected to a device such as a heat pump type hot water heater, and the refrigerant is circulated through the refrigerant flow path and the water is circulated through the water flow path. The heat exchange is carried out in (see, for example, Patent Documents 1 and 2).

JP 60-164183 A Japanese Utility Model Publication No. 60-248996

  However, the above-described conventional double-pipe heat exchanger has a problem that scale is easily deposited on the water flow path, and the water flow path is blocked by the accumulated scale.

  The present invention has been made to solve the above-described problems, and provides a double-pipe heat exchanger capable of preventing the blockage of a flow path by a scale and improving heat exchange performance.

The present invention includes an inner tube having a coolant channel formed therein and an outer tube provided outside the inner tube and having a water channel formed between the inner tube and the spiral tube. In the double pipe heat exchanger bent in a shape, a heat exchange unit having an inner winding double pipe formed so that water circulates in a spiral shape in the water channel, A heat exchange unit having an externally wound double pipe formed so that water flows in a spiral shape through the water flow path is alternately stacked, and the water flow is placed in the lowermost heat exchange unit. The inlet of the channel is provided, the outlet of the water channel is provided in the uppermost heat exchange unit, the heat exchange unit on the outlet side of the water is an externally wound double pipe , and at the end of the uppermost heat exchange unit separated into a water pipe and the inner pipe, it characterized that you place the water tube above said inner tube.

  Preferably, the inner pipe includes a refrigerant pipe and a leak detection pipe provided on an outer periphery of the refrigerant pipe, and a leak detection groove is formed along the pipe direction on the inner surface of the leak detection pipe. .

  According to the present invention, since a long straight portion can be formed on the water outlet side by providing the outer-wound double pipe in the heat exchange unit on the water outlet side, the scale is clogged in the water flow path. Various excellent effects such as being able to prevent heat and maintaining high heat exchange performance can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the present embodiment, a double-pipe heat exchanger that performs heat exchange between a coolant such as carbon dioxide and chlorofluorocarbon used in a device such as a heat pump water heater and water will be described as an example.

  As shown in FIG. 1, the double-pipe heat exchanger 1 has a configuration in which three heat exchange units 2, 3, and 4 are stacked in a step shape. 2, 3 and 4 are provided with double tubes 5 (5a, 5b).

  As shown in FIG. 2, the double pipe 5 is provided with a copper inner pipe 6 and a copper outer pipe 7 provided outside the inner pipe 6. A water flow path 8 is formed, and a water flow path 9 is formed between the inner tube 6 and the outer tube 7. And the refrigerant | coolant which distribute | circulates the flow path 8 for refrigerant | coolants, and the water which distribute | circulates the flow path 9 for water oppose each other, As a result, the heat exchange efficiency between a refrigerant | coolant and water is improved. Can do. The inner pipe 6 includes a copper refrigerant pipe 10 and a copper leakage detection pipe 11 provided on the outer periphery of the refrigerant pipe 10, and the two inner pipes 6 are arranged in parallel in the vertical direction. A large number of leak detection grooves 12 are formed along the pipe direction on the inner surface of the leak detection pipe 11, and an air layer is formed in the leak detection groove 12. The leakage detection groove 12 is connected to a leakage detection sensor (not shown) provided outside, and the refrigerant or water leaking from the inner tube 6 or the outer tube 7 is not mixed with the outside through the leakage detection groove 12. The leak detection sensor detects the leak.

  As shown in FIG. 1, double pipes 5 (5a, 5b) are arranged in two upper and lower stages in the heat exchange units 2 and 3 in the lowermost stage and the middle stage, and the refrigerant and water are divided in parallel. Is flowing. Further, in the lowermost and uppermost heat exchange units 2 and 4, as shown in FIGS. 3 and 4, respectively, the water flows in a spiral shape through the water channel 9. On the other hand, the heat exchange unit 3 in the middle stage is formed so that the water flows in a spiral shape in the water flow path 9 in the middle heat exchange unit 3. An internally wound double pipe 5b is provided. As a result, the water inlet 13 to the double-pipe heat exchanger 1 is located below the outlet 14, so that there is no air reservoir in the water flow path 9, and the water moves up the water flow path 9. Therefore, the air venting performance and the water draining performance in the water channel 9 can be improved, the heat exchange performance can be improved, and the freezing puncture can be prevented. In addition, by providing the outer winding double pipe 5a in the uppermost heat exchange unit 4, a long straight portion can be formed on the outlet side of the water, so that the scale for the water flow path 9 is prevented from being clogged. be able to.

  The water flowing through the water channel 9 contains scale, and the amount of scale deposition in the water channel 9 increases as the temperature of the water flowing through the water channel 9 increases. There is a tendency (as can be seen from FIG. 5, the amount of scale deposition starts to increase rapidly especially when the water temperature exceeds 60 ° C.). Therefore, the ratio of the bending radius R of the bent portion 17 of the outer tube 7 to the inner diameter of the outer tube 7 (hereinafter referred to as “bending radius ratio”) is set according to the water temperature or the amount of scale deposition, and the bending radius ratio of the outer tube 7 Is formed so as to exceed the setting. Specifically, as shown in FIG. 5, when the bend radius ratio of the outer tube is 2.7 or more when the water temperature is 60 ° C., 3.15 or more when the water temperature is 70 ° C., and the water temperature is 80 ° C. Is 4.1 or more, and when the water temperature is 90 ° C., it is 5.3 or more. As a result, the water flow path 9 of the outer tube 7 can be prevented from being blocked by the scale, the heat exchange performance can be maintained high, and the durability of the heat exchanger can be improved.

  As shown well in FIG. 1, the upper end portion of the double pipe 5 is widened by a reducer 26 and the like, and is separated into a water pipe 18 and an inner pipe 6. And after separating into the water pipe 18 and the inner pipe 6, the water pipe 18 is located above the inner pipe 6, and the inner pipe 6 is arranged in parallel in the vertical direction. Thus, by arranging the inner pipes 6 in the vertical direction, it is possible to suppress the resistance of the flow of water and to prevent the water flow path 9 from being blocked by the scale. Moreover, the air venting performance and the water draining performance can be improved by disposing the water pipe 18 above the inner pipe 6.

  Preferably, the cross-sectional area of the water flow path 9 is formed so that the downstream side is larger than the upstream side, and the heat exchange unit in the downstream stage is larger than the heat exchange unit in the upstream stage. Further, as shown in FIG. 1 and FIG. 4, the diameter of the vicinity of the outlet 15 of the water pipe 18 is preferably increased. In these cases, the resistance of the water flow in the water flow path 9 of the outer tube 7 can be kept low, so that the water flow path 9 can be prevented from being blocked by the scale.

  As shown in FIGS. 1, 3, and 4, a required number of metal pipes 19 are brazed between the heat exchange units 2, 3, and 4 of each stage. Thus, by providing the metal pipe 19, the stability of the heat exchange units 2, 3, 4 of each stage is improved, and between the heat exchange units 2, 3, 4 of each stage is improved by the metal pipe 19. Since the gap is formed, the heat transfer between the heat exchange units 2, 3 and 4 at each stage is blocked, and the heat exchange efficiency can be improved. In addition, it is not limited to the above-described metal pipe 19 that is interposed between the heat exchange units 2, 3, 4 of each stage, and may be another support member. A heat insulating means may be interposed, such as by sticking a heat insulating double-sided tape to a required portion between 3 and 4 and fixing the heat exchange units 2, 3, 4 of each stage with the heat insulating double-sided tape. In this case, since the heat exchange units 2, 3, and 4 of each stage are securely fixed with a gap therebetween, the stability is improved and the stacking operation of the heat exchange units 2, 3, and 4 is easy. Thus, the shape accuracy of the heat exchanger 1 after lamination can be increased. Moreover, the interruption | blocking performance of the heat transfer between the heat exchange units 2, 3, and 4 of each stage can further be improved, and heat exchange efficiency can be improved. Further, a resin plate-like member may be used as a support member interposed between the heat exchange units 2, 3, 4 of each stage. For example, as shown in FIG. The pair of resin plate-like members 31 are opposed to each other through the hollow portion 30, and the positioning support pieces 32 are formed vertically from the respective resin plate-like members 31, and the double pipe 5 is formed by the positioning support pieces 32. It may be configured to be aligned. As a result, the hollow portion 30 can improve the heat transfer blocking performance between the heat exchange units 2, 3, and 4 at each stage, and the positioning support piece 32 allows the double pipes 5 a and 5 b to be improved. Installation work can be simplified, and stability after lamination can be increased.

  Further, as shown in FIGS. 1, 3, and 4, the heat exchange unit 2 at the lowermost stage and the heat exchange unit 3 at the intermediate stage, and the Between the upper heat exchange unit 4, the outer tubes 9 are connected to each other via a header 15. In this case, the water temperature in the vicinity of the outlet of the heat exchange unit 3 in the middle stage is 60 to 70 ° C. in the temperature range where the amount of scale deposition in the water flow path 9 starts to increase rapidly. The exchange unit 4 is composed of a single double pipe 5 having an outer pipe 7 having a diameter larger than that of the outer pipe 7 of the intermediate stage heat exchange unit 2, so that scale does not easily accumulate in the water flow path 9. It has become.

  As shown in detail in FIG. 6, the header 15 between the intermediate heat exchange unit 13 and the uppermost heat exchange unit 4 closes the cylindrical pipe 20 and both ends of the pipe 20. The outer tube 7 is welded to the header 15 by brazing or the like through a hole (not shown) drilled in the pipe, the inner tube 6 penetrates the header 15, and the header penetration 22 Is welded by brazing or the like. Further, the refrigerant pipes 10 are connected to each other through the block-shaped header 16 because the refrigerant pressure is high. A vertical hole 23 is formed in the header 16, and an opening end portion of the vertical hole 23 is closed by a cap 24, and each refrigerant pipe 10 is connected to the header 16 so as to communicate with the vertical hole 23. The part 25 is welded by brazing or the like. The length a from the header penetration part 22 of the inner pipe 6 to the opening end face of the leak detection pipe 11 and the length b from the opening end face of the leak detection pipe 11 to the header connection part 25 of the refrigerant pipe 10 are both internal. It is longer than the length corresponding to the tube diameter. Thereby, the brazing material or the like does not flow into the leakage detection groove 12 when the header penetration part 22 and the header connection part 25 are welded, and the leakage detection groove 12 is not blocked. Thus, since the outer pipe 7 and the refrigerant pipe 10 are connected to the separate headers 15 and 16, respectively, and the opening end face of the leak detection pipe 11 is separated from the welded portion by a predetermined distance, the leakage of water or refrigerant Detection can be performed easily and reliably, and leakage detection accuracy can be increased. Moreover, even if the diameters of the outer pipe 7 or the refrigerant pipe 10 are different for each stage by performing the connection between the heat exchange units 2, 3 and 4 via the headers 15 and 16, the connection work is performed. This can be easily performed, productivity can be improved, and manufacturing costs can be suppressed.

  In addition, the connection between the outer pipes 9 at the inlet 13 portion of the water pipe 18 of the lowermost heat exchange unit 2 is made through the header 27. As shown in detail in FIG. 7, the header 27 has the same structure as the header 15 described above, and the outer tube 7 is fixed to the header 27 by brazing or the like. The inner pipe 6 penetrates the header 27, and the refrigerant pipe 10 is connected via a header 28 having the same structure as the header 16 described above.

  In the above embodiment, the double pipes 5a and 5b are arranged in two upper and lower stages only in the heat exchange units 2 and 3 at the lowermost stage and the middle stage. Alternatively, the double pipes 5a may be arranged in two upper and lower stages, and the number of installation stages of the double pipes of the heat exchange units 2, 3, and 4 may be three or more.

  Further, the number of stacked layers of the heat exchange units 2, 3, and 4 is not limited to the above-described three steps, and may be two or four or more.

  Furthermore, the number of installed inner pipes 6 is not limited to two, and may be three or more. Moreover, although the leak detection pipe | tube 11 is provided in the outer peripheral part in the inner pipe 6, this invention is applicable also to the double pipe type heat exchanger without the leak detection pipe | tube 11. FIG.

  Furthermore, in the above-described embodiment, the case where heat is exchanged between the refrigerant and water has been described, but this is merely an example, and the present invention includes, for example, the case where heat is exchanged between water and water. The present invention is also applicable when heat is exchanged between other fluids.

It is a front view which shows the double tube | pipe type heat exchanger which concerns on embodiment of this invention. It is sectional drawing which shows the double tube | pipe type heat exchanger which concerns on embodiment of this invention. It is an AA arrow line view of FIG. It is a top view which shows the double tube | pipe type heat exchanger which concerns on embodiment of this invention. It is a figure which shows the relationship between a bending radius ratio, water temperature, and the amount of scale deposits in the double-pipe heat exchanger which concerns on embodiment of this invention. It is sectional drawing which shows the detail of the header in embodiment of this invention. It is sectional drawing which shows the detail of the header in embodiment of this invention. It is a sectional side view which shows another example of the supporting member in embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Double pipe type heat exchanger 2 Heat exchange unit 3 Heat exchange unit 4 Heat exchange unit 5 Double pipe 6 Inner pipe 7 Outer pipe 8 Refrigerant flow path 9 Water flow path 11 Leak detection tube 14 Outlet

Claims (2)

It has an inner tube with a coolant channel formed inside, and an outer tube that is provided outside the inner tube and has a water channel formed between the inner tube and is bent in a spiral shape. In the double-tube heat exchanger
A heat exchanging unit having an inner winding double pipe formed so that water flows in a spiral shape in the water channel, and water flows in a spiral shape in the water channel. The heat exchange unit having an outer-wound double pipe formed so as to be stacked is alternately laminated, and the lowermost heat exchange unit is provided with an inlet for the water flow path, and the uppermost heat exchange unit is used for water. An outlet of the flow path is provided, the heat exchange unit on the water outlet side is an externally wound double pipe , and the water pipe is separated into an inner pipe at the end of the uppermost heat exchange unit. double pipe heat exchanger, characterized that you located more upward. The said inner pipe consists of a refrigerant pipe and the leak detection pipe provided in the outer periphery of this refrigerant pipe, The leak detection groove | channel is formed in the inner surface of this leak detection pipe along the piping direction. Double tube heat exchanger.

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