JP2011017476A - Double tube type heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a compact double tube type heat exchanger of high performance with no problem resulting from the eccentricity of an inner tube.SOLUTION: The double tube type heat exchanger is obtained by working a double tube 10 including the inner tube with a first fluid flowing through inside, and an outer tube arranged outside the inner tube to allow a second fluid to flow through a clearance between itself and the inner tube, into shape having first circular arc parts 11a, 11b, 11c repeated by turns, and second circular arc parts 12a, 12b, 12c having reverse curvature to the first circular arc parts.

Description

  The present invention comprises an inner tube and an outer tube disposed on the outer side of the inner tube, a first fluid is circulated inside the inner tube, and a second fluid is disposed in the gap between the outer tube and the inner tube. It is related with the double pipe type heat exchanger which distributes heat and performs heat exchange between this 1st fluid and this 2nd fluid.

  2. Description of the Related Art Conventionally, as a heat exchanger for exchanging heat between a heat exchange medium (refrigerant) and a fluid such as water, a flow path for circulating a refrigerant and a flow path for a fluid heated by heat exchange such as water are provided. Various heat exchangers configured by combining two heat transfer tubes so as to exchange heat between water or the like and a refrigerant have been used.

  Various types of heat exchangers that exchange heat between the refrigerant and water have been proposed. Among them, an inner tube and an outer tube installed outside the inner tube are proposed. The double-tube heat exchanger consisting of the above has a simple structure, is easy to produce, and has good heat exchange performance.

  For example, in Japanese Patent Laid-Open No. 2006-170571 (Patent Document 1), a double multi-tube including a plurality of inner tubes twisted in a spiral shape and an outer tube into which the inner tubes are inserted has a rectangular shape. A spirally wound double multi-tube heat exchanger is disclosed.

  JP 2005-147466 A discloses a double multi-tube heat in which a double multi-tube composed of an inner tube and an outer tube installed outside the inner tube is wound in a rectangular spiral shape. An exchanger is disclosed.

JP 2006-170571 A (Claims, FIG. 1) Japanese Patent Laying-Open No. 2995-147666 (Claims, FIG. 3)

  In the double tube heat exchanger of Patent Document 1 or 2, the refrigerant channel tube on the high temperature side is completely enclosed in the water channel tube on the low temperature side, so that the heat of the refrigerant is transferred to the outside air. Although it has the advantage that it is suppressed from being released, it has the disadvantage that it is difficult to increase the heat transfer area to the water side.

  As a means for increasing the heat transfer area to the water side, for example, in Japanese Patent Laid-Open No. 2001-201275 (Patent Document 3), helical heat transfer is promoted in the gap between the outer tube and the inner tube serving as a water flow path. A double-pipe heat exchanger with a body interposed therein is disclosed.

  However, the double-pipe heat exchanger of Patent Document 3 is not preferable because there is a problem that a scale is easily formed in the water flow path.

  Therefore, in order to increase the heat transfer area on the water side, it is currently necessary to rely on means for increasing the length of the heat exchanger.

  However, increasing the length of the heat exchanger of Patent Document 1 or 2 increases the number of rectangular windings in the plane direction or the height direction, or increases the diameter of the rectangular windings. The size of the heat exchanger increases and the weight increases. Therefore, it goes against the recent demand for compactness.

  Further, when the double tube is processed into a rectangular spiral shape, the inner tube is eccentric to the center side of the spiral with respect to the outer tube. FIG. 9 shows a plan view of a double tube heat exchanger in which the double tube is processed into a rectangular spiral shape. FIG. 10 is a cross-sectional view of the bending portion 63 taken along a plane perpendicular to the fluid flow direction in the yy cross section in FIG. 9.

  In FIG. 9, a double-pipe heat exchanger 61 is obtained by processing a double tube 62 composed of an inner tube and an outer tube disposed outside the inner tube into a rectangular spiral shape. The double pipe 62 includes a straight portion 64 and a bent portion 63. As shown in FIG. 10, the inner tube 67 is eccentric to the central side 66 of the rectangular spiral within the outer tube 68.

  When the double pipe heat exchanger 61 allows the refrigerant to flow through the inner pipe 67 and the water to flow through the gap between the outer pipe 68 and the inner pipe 67, the bent section 63 causes the inner pipe to 67 is eccentric with respect to the outer tube 68, the water channel area (when viewed in a cross section perpendicular to the direction of the water channel) between the rectangular spiral center side 66 and the rectangular spiral outer side 65. Area) is different, the water channel area on the outer side 65 of the rectangular spiral is large, and the water channel area on the center side 66 of the rectangular spiral is small. In the bent portion 63, the water channel area on the outer side 65 of the rectangular spiral of the water channel is always large, and the water channel area on the center side 66 of the rectangular spiral is small.

  For this reason, a rectangular spiral double tube heat exchanger such as the heat exchanger of Patent Document 1 or 2 has a flow path area (area when viewed in a cross section perpendicular to the flow path direction). As a result, the turbulent flow is sufficient because there is a thin region of the velocity boundary layer and temperature boundary layer in only one direction of the flow path and the renewal of these boundary layers is prevented. There is a problem that an accelerating effect cannot be obtained, and there is also a problem that scale is likely to precipitate due to an increase in the degree of superheating of the inner wall surface where the flow resistance of water is large.

  Accordingly, an object of the present invention is to provide a compact and high-performance double-pipe heat exchanger that is free from problems due to the eccentricity of the inner tube, has high heat exchange performance per unit length, and is compact. .

  As a result of intensive studies to solve the problems in the prior art, the present inventors have repeated a double tube consisting of an inner tube and an outer tube arranged outside the inner tube alternately. A double pipe heat exchanger obtained by processing into a shape comprising one arc portion and a second arc portion having a curvature opposite to that of the first arc portion is such that the inner tube is in relation to the outer tube. Even if it is knitted, the eccentric direction is repeatedly reversed at relatively short intervals, so that (1) the problem due to the eccentricity of the inner tube does not occur, and therefore (2) the scale due to the increase in the degree of superheat on the wall surface The inventors have found that precipitation can be suppressed, and that (3) the heat exchanger is soaked and heat exchange performance is improved, and the present invention has been completed.

  That is, the present invention provides a double pipe comprising an inner tube through which a first fluid flows and an outer tube disposed outside the inner tube and through which a second fluid flows in a gap with the inner tube. Provided is a double-tube heat exchanger obtained by processing a tube into a shape consisting of a first arc portion that is alternately repeated and a second arc portion having a curvature opposite to that of the first arc portion. Is.

  ADVANTAGE OF THE INVENTION According to this invention, there is no problem resulting from the eccentricity of an inner pipe | tube, and the heat exchange performance per unit length is high, and a compact and high performance double pipe type heat exchanger can be provided.

It is a typical sectional view of a double tube before being processed into the shape of a double tube concerning a double tube type heat exchanger of the present invention. It is the example of the expansion | extension shape of the planar direction of the double pipe after a process, and is the schematic diagram which planarly viewed the double pipe after a process. It is the figure which extracted one part of the 1st circular arc part and the 2nd circular arc part in FIG. It is sectional drawing of the double pipe after the said process in FIG.2 and FIG.3. It is a schematic diagram of the other example of the expansion | extension shape of the planar direction of the double pipe after a process. It is a schematic diagram of the form example which this 1st circular arc part and this 2nd circular arc part are connected via the linear part. It is a typical sectional view of a double pipe which consists of two inner pipes and an outer pipe arranged on the outside of the inner pipe. It is a schematic diagram which shows a two-stage heat exchanger. It is a figure which shows the conventional double pipe type heat exchanger. FIG. 10 is a cross-sectional view of the bending portion 63 taken along a plane perpendicular to the fluid flow direction in the yy cross section in FIG.

  The double pipe heat exchanger of the present invention includes an inner pipe through which a first fluid flows, and an outer pipe arranged outside the inner pipe and through which a second fluid flows through a gap between the inner pipe and the inner pipe. And a double tube type obtained by processing a double tube comprising a first arc portion that is alternately repeated and a second arc portion having a curvature opposite to that of the first arc portion. It is a heat exchanger.

  The double pipe heat exchanger of the present invention is a double pipe heat exchanger obtained by processing the double pipe comprising the inner pipe and the outer pipe arranged outside the inner pipe. is there.

  FIG. 1 shows a schematic cross-sectional view of a double tube before being processed into a double tube shape according to the double tube heat exchanger of the present invention. In FIG. 1, a double tube (double tube before processing) 3 before being processed into the shape of a double tube according to the double tube heat exchanger of the present invention includes an inner tube 1 and the inner tube 1. And an outer tube 2 disposed on the outer side of the tube. The inner tube 4 after processing the double tube 3 before processing is a flow path through which the first fluid flows, and the gap between the outer tube 2 and the inner tube 1 5 is a flow path through which the second fluid flows. The first fluid is circulated through the interior 4 of the inner tube 1, and the second fluid is circulated through the gap 5 between the outer tube 2 and the inner tube 1. Heat exchange is performed with the second fluid.

  The shape of the double pipe (double pipe after processing) according to the double pipe heat exchanger of the present invention will be described with reference to FIGS. 2 to 4 are configuration examples of the elongated shape in the planar direction of the double tube after the processing, FIG. 2 is a schematic view in plan view of the double tube after the processing, FIG. FIG. 4 is a diagram in which one portion of the first arc portion and the second arc portion in FIG. 2 is extracted, and FIG. 4 is a cross-sectional view of the double pipe after the processing in FIGS. 2 and 3. In the present invention, the shape of the double pipe after processing is the shape of the outer pipe. Further, the inner pipe is disposed inside the outer pipe.

  In FIG. 2, the shape of the double pipe 10 after processing is a shape including a first arc portion 11 and a second arc portion 12. Then, as shown in FIG. 2, the first arc portion 11a, the second arc portion 12a, the first arc portion 11b, the second arc portion 12b, the first arc portion 11c, and the second arc portion 12c in this order. The first arc portion 11 and the second arc portion 12 are alternately repeated. The inflection point 13a to the inflection point 13b is the first arc portion 11a, and the inflection point 13b to the inflection point 13c is the second arc portion 12a. The inflection point 13d is the first arc portion 11b, the inflection point 13d to the inflection point 13e is the second arc portion 12b, and the inflection point 13e to the inflection point 13f is the first arc portion 11b. One arc portion 11c, and from the inflection point 13f to the inflection point 13g is the second arc portion 12c. In the shape of the double pipe 10 after processing shown in FIG. 2, the first arc portion 11 and the second arc portion 12 are directly connected at the inflection point 13.

  In the processed double pipe 10, the second fluid 15 passes through the gap between the outer pipe and the inner pipe from one end 14 a of the gap between the outer pipe and the inner pipe. And flows toward the other end 14b of the gap between the inner pipe and the inner pipe. In addition, the first fluid normally flows in the opposite direction to the second fluid 15 from the one end of the inner tube toward the other end of the inner tube.

  FIG. 3 is a diagram in which the first arc portion 11a and the second arc portion 12a in FIG. 2, that is, a portion from the inflection point 13a to the inflection point 13c are extracted. The first arc portion 11a and the second arc portion 12a have opposite curvatures. In the present invention, the fact that the curvature of the arc is reversed will be described with reference to FIGS. 2 and 3. When the curvature of the arc is reversed, the position of the center of curvature of the arc is the same as that of the outer tube. A relationship that is opposite to the left and right in the direction of travel of the second fluid flowing through the gap with the inner pipe. That is, when the second fluid flows through the gap between the outer tube and the inner tube, the relationship between the arc that curves to the right and the arc that curves to the left is the curvature of the arc. Says the opposite. For example, in FIG. 3, the center of curvature of the first arc portion 11 a is the position indicated by reference numeral 16 a and is on the right side in the flow direction 17 of the second fluid. On the other hand, the center of curvature of the second arc portion 12a is the position indicated by reference numeral 16b, and is on the left side in the flow direction 17 of the second fluid.

  When the double pipe before processing is processed, the outer pipe is restrained by a jig, while the inner pipe is in a state of floating in the hollow. Therefore, since the inner tube is difficult to bend, the bending of the inner tube becomes gentler than the bending of the outer tube. Therefore, in the outer tube, the inner tube is eccentric with respect to the outer tube.

  The eccentricity of the inner tube will be described with reference to FIG. In FIG. 4, sectional views taken along line xx from point A to point I of the double tube 10 after processing are (A) to (I). 4 (A) to (I) are cross-sectional views of the processed double pipe 10 taken along a plane perpendicular to the flow direction of the second fluid, It is sectional drawing seen in the distribution direction of the 2nd fluid. That is, in (A) to (I) in FIG. 4, the direction from the front surface to the back surface of the paper is the flow direction of the second fluid.

  4A is a cross-sectional view of the point A, that is, the inflection point 13a, and is a cross-sectional view of the inlet portion of the second fluid to the first arc portion 11a. As shown in (A), at the point A, the inner tube is not eccentric with respect to the outer tube. Therefore, the flow area of the second fluid flowing through the gap between the outer pipe and the inner pipe (the area when viewed in a cross section perpendicular to the direction of the flow path) is biased to the left and right. Absent.

  Point B is a position slightly advanced from the point A through the first circular arc portion 11a in the direction of flow of the second fluid. As shown in (B), the inner pipe is located with respect to the outer pipe. Is slightly eccentric to the right. Therefore, the flow path area of the second fluid flowing through the gap between the outer tube and the inner tube is uneven on the left and right, and the right side is smaller than the left side.

  The point C is a position further advanced from the point B through the first arc portion 11a in the flow direction of the second fluid, and is an intermediate point of the first arc portion 11a. At this time, as shown in (C), the inner tube is greatly decentered to the right with respect to the outer tube, and the degree of decentering is maximized in the first arc portion 11a. Therefore, the left-right deviation of the flow path area of the second fluid flowing through the gap between the outer tube and the inner tube is maximized in the first arc portion 11a.

  The point D is a position further advanced from the point C through the first circular arc portion 11a in the direction of flow of the second fluid. As shown in (D), the inner pipe is located with respect to the outer pipe. It is slightly eccentric to the right side, and the degree of eccentricity is smaller than the point C. Therefore, the left and right deviations in the flow area of the second fluid flowing through the gap between the outer tube and the inner tube are smaller than the point C.

  Point E is the inflection point 13b, and is the exit portion of the first arc portion 11a of the second fluid. As shown in (E), at the point E, the inner tube is not eccentric with respect to the outer tube. Therefore, the flow area of the second fluid flowing through the gap between the outer tube and the inner tube is not biased to the left or right. The point E is also an entrance portion of the second fluid into the second arc portion 12a.

  The point F is a position slightly advanced from the point E through the second arcuate portion 12a in the second fluid flow direction. As shown in (F), the inner pipe is located with respect to the outer pipe. This time it is slightly eccentric to the left. Therefore, the flow channel area of the second fluid flowing through the gap between the outer tube and the inner tube is smaller on the left side than on the right side.

  Point G is a position further advanced from the point F through the second arc portion 12a in the flow direction of the second fluid, and is an intermediate point of the second arc portion 12a. At this time, as shown in (G), the inner tube is greatly decentered to the left with respect to the outer tube, and the degree of decentering is maximized in the second arc portion 12a. Therefore, the left-right deviation of the flow path area of the second fluid flowing through the gap between the outer tube and the inner tube is maximized in the second arc portion 12a.

  The point H is a position further advanced from the point G through the second arcuate portion 12a in the second fluid flow direction. As shown in (H), the inner tube is located with respect to the outer tube. The left side is slightly eccentric, and the degree of eccentricity is smaller than the point G. Therefore, the right and left bias of the flow area of the second fluid flowing through the gap between the outer tube and the inner tube is smaller than the point G.

  Point I is the inflection point 13c, and is the exit portion of the second arc portion 12a of the second fluid. As shown in (I), at the point I, the inner tube is not eccentric with respect to the outer tube. Therefore, the flow area of the second fluid flowing through the gap between the outer tube and the inner tube is not biased to the left or right. The point I is also an entrance portion of the second fluid into the first arc portion 11b.

  As shown in FIG. 4, in the double pipe heat exchanger according to the present invention, the first arc portion and the second arc portion whose arc curvatures are opposite to each other are alternately repeated. Thus, even if the inner tube is eccentric with respect to the outer tube, the eccentric direction is repeatedly reversed at a relatively short interval, so that the problem due to the eccentricity of the inner tube does not occur. In other words, since the eccentricity is reversed in a short cycle, the effect of promoting turbulent flow that updates the temperature boundary layer and the velocity boundary layer is obtained, so that the heat exchanger is soaked and the heat exchange performance is improved. Further, since the direction in which the flow path area is reduced is not biased to only one direction, an effect of suppressing scale deposition resulting from an increase in the degree of superheating of the wall surface can be obtained.

  In FIG. 3, the central angle (°) of the first arc portion 11a and the central angle (°) of the second arc portion 12a are denoted by θ. The central angle θ of the first arc portion 11a is one end of the first arc portion 11a (the start point of the first arc portion 11), that is, the inflection point 13a and the center of curvature 16a of the first arc portion 11a. And the other end of the first arc portion 11a (the end point of the first arc portion 11), that is, the angle formed by the inflection point 13b. Similarly, the central angle θ of the second arc portion 12a is equal to one end of the second arc portion 12a (the start point of the second arc portion 12), that is, the inflection point 13b and the second arc portion 12b. This is the angle formed by the curvature center 16b and the other end of the second arc portion 12a (the end point of the second arc portion 12), that is, the inflection point 13c.

  Further, in FIG. 3, the radius of curvature (mm) of the first arc portion 11a and the radius of curvature (mm) of the second arc portion 12a are denoted by R. The radius of curvature R of the first arc portion 11a is the distance between the center line of the outer tube of the first arc portion 11a and the center of curvature 16a of the first arc portion 11a. The center line of the outer pipe is a line in which the center of the outer pipe in a cross section perpendicular to the flow direction of the second fluid is connected to the flow direction of the second fluid. The same applies to the radius of curvature of the second arcuate portion 12a.

  FIG. 5 shows an example in which θ of the first arc portion and the second arc portion is 180 °.

In the double pipe heat exchanger of the present invention, when the outer diameter of the outer pipe is D (mm), the following formula (1):
1 ≦ R / D ≦ 10 (1)
Is preferably satisfied, and 2 ≦ R / D ≦ 7 is particularly preferable. When the value of R / D is within the above range, the effect of promoting turbulent flow and the effect of suppressing scale precipitation are enhanced. On the other hand, if the value of R / D exceeds the above range, these effects are likely to be low, and if it is less than the above range, failures such as buckling of the heat transfer tube are likely to occur, resulting in a decrease in reliability. In addition to being easily invited, the eccentricity of the inner tube becomes too large and partial blockage is likely to occur. The outer diameter D of the outer tube is an outer diameter of a cross section when the outer tube is cut along a plane perpendicular to the water flow direction.

  θ is preferably 60 to 290 °, particularly preferably 180 to 290 °. When θ is in the above range, the effect of promoting turbulence and the effect of suppressing scale precipitation are enhanced.

In the double pipe heat exchanger of the present invention, there may be a difference in length between the first arc part and the second arc part when the double pipe is processed. There may be a difference in the lengths of the first arc portion and the second arc portion as long as the effect is not impaired. In the double-tube heat exchanger of the present invention, when the length of the first arc portion is X1 (mm) and the length of the second arc portion is X2 (mm), the following formula (2) :
0.9 ≦ X1 / X2 ≦ 1.1 (2)
It is preferable that 0.95 ≦ X1 / X2 ≦ 1.0. When the value of X1 / X2 is within the above range, the effect of promoting turbulent flow and the effect of suppressing scale precipitation are enhanced, and the heat exchange performance is enhanced.

  In the embodiment shown in FIGS. 2 and 3, the first arc portion 11 and the second arc portion 12 are directly connected at the inflection point 13. The distance from the end of the second arc portion 12 (the distance between the start point of the first arc portion 11 and the end point of the second arc portion 12 and the end point of the first arc portion 11 and the second arc portion 12 The distance from the start point) is 0 (mm).

  In the double tube heat exchanger of the present invention, the shape of the double tube after processing may be such that the first arc portion and the second arc portion are not directly connected to each other. It may be connected via a straight line portion as shown in the embodiment. In addition, FIG. 6 extracts and shows one each of the 1st circular arc part 21, the 2nd circular arc part 22, and this linear part 25 which are connected via the linear part among the shapes of this double pipe after processing. Actually, the first arc portion 21, the straight portion 25, the second arc portion 22, the straight portion 25, the first arc portion 21, the straight portion 25, the second arc portion 22, Like the straight line portions 25, the first arc portion 21 and the second arc portion 22 are alternately repeated with the straight portion 25 interposed therebetween.

  In the linear portion 25 of the embodiment shown in FIG. 6, the inner tube is not eccentric with respect to the outer tube.

  The length L between ends will be described with reference to FIG. The distance between the end of the first arc 21 and the end of the second arc 22 (the distance between the start point of the first arc 21 and the end of the second arc 22 and the first arc 21 The distance between the end point of the second arc part 22 and the start point of the second arc part 22) is defined as a length L (mm) between the end part of the first arc part and the end part of the second arc part. In FIG. 6, the first arc portion 21 and the second arc portion 22 are connected to both ends of the linear portion 25. That is, one end of the first arc portion 21 (end point of the first arc portion) and one end of the linear portion are connected by the connection point 24, and the other end of the linear portion 25 and the second arc portion 22 One end (the start point of the second arc portion) is connected at the connection point 26. An end-to-end length L between the end of the first arc portion and the end of the second arc portion is the length of the linear portion 25.

In the double tube heat exchanger of the present invention, the length L between the end of the first arc portion and the end of the second arc portion, the first arc portion and the second arc portion The radius of curvature R of the arc portion is the following formula (3):
0 ≦ L / R ≦ 1 (3)
It is preferable that 0 ≦ L / R ≦ 0.5.

  More preferably, the first arc portion and the second arc portion are directly connected. When the first arc portion and the second arc portion are directly connected, the length L between the end portions is 0 mm. That is, the value of L / R is more preferably 0.

  2 to 6, the first arc portion and the second arc portion are part of a perfect circular arc. However, in the double tube heat exchanger of the present invention, the double tube During the processing, the first arc portion and the second arc portion may have a shape obtained by deforming a perfect circle, but the first arc portion and the second arc portion are within a range that does not impair the effects of the present invention. The second arc portion may have a shape slightly deformed from a perfect circular arc.

  Although FIGS. 1-6 shows the example of the form of the double tube | pipe with one inner tube arrange | positioned inside an outer tube | pipe, this double tube | pipe which concerns on the double tube | pipe type heat exchanger of this invention Is not limited to this. For example, there are two types including two inner pipes 31 and an outer pipe 32 disposed outside the inner pipe 31 as shown in FIG. A heavy pipe is mentioned. Further, the double pipe may have three or more inner pipes. When the number of the inner tubes installed inside the outer tube is two or more, the shape may be such that two or more inner tubes are twisted in a spiral shape.

  In the double tube heat exchanger of the present invention, the inner tube may be provided with a leakage detection structure.

  In the double tube heat exchanger of the present invention, the first fluid flows inside the inner tube, and the second fluid flows in the gap between the inner tube and the outer tube. Then, heat exchange is performed between the first fluid and the second fluid.

  The second fluid is not particularly limited. In the case where the double pipe heat exchanger of the present invention is for hot water supply, the second fluid is water.

  The first fluid is not particularly limited. The first fluid may be a refrigerant mainly composed of carbon dioxide. The refrigerant mainly composed of carbon dioxide is carbon dioxide alone or a carbon dioxide refrigerant containing 0 to 15% by mass of refrigerating machine oil.

  In the double pipe heat exchanger of the present invention, when the second fluid is water, and the material of the outer tube and the material of the inner tube are copper or a copper alloy, the inner surface of the outer tube and The outer surface of the inner tube is tin-plated, so that it is possible to suppress the copper or copper alloy that is the tube material from being dissolved into water as divalent copper ions. It is preferable in that the suppression of blue water generation and the corrosion resistance of the heat exchanger can be advantageously ensured.

  FIG. 2 shows an example in which the first arc portion and the second arc portion are repeated on one plane, but the double-tube heat exchanger of the present invention is not limited to this. The first arc portion and the second arc portion may be repeated on two or more planes. FIG. 8 is a schematic diagram showing the shape of a double tube according to a two-stage heat exchanger. In FIG. 8, the second stage 42 in which the first arc part and the second arc part are repeated is arranged on the first stage 41 in which the first arc part and the second arc part are repeated. One end of the inner pipe of the first stage 41 and one end of the inner pipe of the second stage 42, and one end of the outer pipe of the first stage 41 and one end of the outer pipe of the second stage 42 are They are connected by a joint 43 that is a double pipe. In FIG. 8, the first stage 41 is shown in black, the second stage 42 is shown in dark gray, and the joint 43 is shown in light gray.

  Since the double pipe according to the double pipe heat exchanger of the present invention is usually obtained by processing a seamless double pipe, the outer pipe and the inner pipe are one continuous tube body. It is. Therefore, when the first arc portion and the second arc portion of the double pipe (the outer pipe) are repeated in one plane, the outer pipe and the inner pipe are usually a continuous seamless pipe. It is formed with. In the case of a multi-stage in which the first arc portion and the second arc portion of the double pipe (the outer pipe) are repeated on two or more planes, the outer pipe and the inner pipe at each stage are usually used. Is formed by one continuous seamless pipe, or the outer pipe and the inner pipe are formed by one continuous seamless pipe over two or more stages.

  EXAMPLES Next, although an Example is given and this invention is demonstrated more concretely, this is only an illustration and does not restrict | limit this invention.

(Example 1 and Comparative Example 1)
<Production of Heat Exchanger of Example 1>
A heat exchanger having the shape of a double pipe (outer pipe) shown in FIG. 2 was produced with the following dimensions.
-Double ring heat exchanger-Outer tube: outer diameter (D) = 16 mm, wall thickness = 0.7 mm, material is phosphorous deoxidized copper-Inner tube: outer diameter = 6 mm, wall thickness = 0.5 mm, material Is the radius of curvature R of the first and second arcs of phosphorus-deoxidized copper / outer tube R = 64mm
・ Center angle θ = 290 ° of the first and second arc portions of the outer tube
・ The number of first arcs of the outer tube = 3, the number of second arcs of the outer tube = 3, and the length L between the ends of the outer tube = 0 mm.
・ R / D = 4, L / R = 0
・ Overall length of double pipe = 2300mm
-Plane occupation area S of double pipe S = 130,000 mm ² (Plane occupation width W1 of double pipe = 520 mm, plane occupation depth T1 of double pipe = 250 mm)

<Production of Heat Exchanger of Comparative Example 1>
The heat exchanger shown in FIG. 9 was produced with the following dimensions.
-Double ring heat exchanger-Outer tube: outer diameter (D) = 16 mm, wall thickness = 0.7 mm, material is deoxidized copper-Inner tube: outer diameter = 6 mm, wall thickness = 0.5 mm, material is Deoxidized copper, rectangular spiral, quadruple, double tube total length = 4500mm
-Plane occupied area S of double pipe S = 130,000 mm ² (Plane occupied width W2 of double pipe = 520 mm, plane occupied depth T2 of double pipe = 250 mm)

<Performance evaluation>
-Evaluation method The carbon dioxide refrigerant gas was circulated inside the inner pipe, and water was passed through the annular portion between the inner pipe and the outer pipe under the conditions shown in Table 1, and the heat exchange performance was measured.

<Evaluation results>
When the heat exchange amount of Example 1 and Comparative Example 1 at a water flow rate of 1 L / min was compared, the heat exchange amount of Example 1 was 50% greater than the heat exchange amount of the Comparative Example. When this is compared with the heat exchange amount per unit mass (per unit length) of the heat exchanger, the heat exchange amount per unit mass of the heat exchanger of Example 1 is 2.9 times that of Comparative Example 1. It was.

  ADVANTAGE OF THE INVENTION According to this invention, the double pipe type heat exchanger excellent in heat exchange performance can be manufactured.

1, 31 Inner tube 2, 32 Outer tube 3 Double tube 4 Inside 5 of inner tube 1 Gap 11, 21 between outer tube 2 and inner tube 1 First arc portion 12, 22 Second arc portion 13 Bend point 14 One end 15 of the gap between the outer pipe and the inner pipe 15 Second fluid 16 Center of curvature 17 Flow direction 24, 26 of the second fluid Connection point 25 Straight line portion 41 First stage 42 Second stage 43 Joint 61 Heat exchanger 62 Double pipe 63 Curved portion 64 Straight portion

Claims (6)

  A double pipe consisting of an inner pipe through which the first fluid flows and an outer pipe arranged outside the inner pipe and through which the second fluid flows through the gap between the inner pipe and the inner pipe is alternately repeated. A double-tube heat exchanger obtained by processing the first arc portion and the second arc portion having a curvature opposite to that of the first arc portion. When the radius of curvature of the first arc portion and the second arc portion of the outer tube is R (mm) and the outer diameter of the outer tube is D (mm), the following formula (1):
1 ≦ R / D ≦ 10 (1)
The double pipe heat exchanger according to claim 1, wherein: When the length of the first arc portion of the outer tube is X1 (mm) and the length of the second arc portion of the outer tube is X2 (mm), the following formula (2):
0.9 ≦ X1 / X2 ≦ 1.1 (2)
The double pipe heat exchanger according to claim 1, wherein:   The double pipe heat exchanger according to any one of claims 1 to 3, wherein the second fluid is water.   5. The double-tube heat exchanger according to claim 1, wherein the second fluid is water and the first fluid is a refrigerant mainly composed of carbon dioxide.   The second fluid is water, the material of the outer tube and the material of the inner tube are copper or a copper alloy, and tin plating is applied to the inner surface of the outer tube and the outer surface of the inner tube. The double-tube heat exchanger according to any one of claims 4 and 5, wherein