JP2018048773A - Heat exchanger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To substantially secure a contact area between a gaseous phase refrigerant and a heat transfer pipe.SOLUTION: A heat exchanger (13) includes: a shell (20); and a plurality of heat transfer pipes (30) arranged inside the shell (20). The plurality of heat transfer pipes (30) are arranged in parallel with each other. Each of the plurality of heat transfer pipes (30) has a first corner part (31). The first corner part (31) constitutes a portion located at the lowest in each of the plurality of transfer pipes (30) in the vertical direction. The first corner part (31) of a first heat transfer pipe (30A) is in a position being separated in the horizontal direction from an apex (33p) of a second heat transfer pipe (30B). Each of the plurality of heat transfer pipes (30) has three or over three portions showing a contour of a curvature radius smaller than a radius of a circle which has the same area as a cross-sectional area of each of the plurality of heat transfer pipes (30).SELECTED DRAWING: Figure 3

Description

  The present disclosure relates to a heat exchanger.

  A shell and tube heat exchanger is known as a heat exchanger used for condensing the refrigerant. FIG. 21 is a cross-sectional view of a conventional shell and tube heat exchanger described in Patent Document 1.

  As shown in FIG. 21, the conventional shell and tube heat exchanger includes a shell 1 and a plurality of heat transfer tubes 2. The shell 1 has an inlet 4 and an outlet 5. A high-temperature and gas-phase refrigerant is introduced into the shell 1 from the inlet 4. The refrigerant is cooled by the cooling water flowing through the heat transfer tube 2 and is liquefied on the surface of the heat transfer tube. As a result, a liquid-phase refrigerant is generated. The liquid-phase refrigerant flows downward and is discharged from the outlet 5 to the outside of the shell 1.

JP-A-8-159611

  In order to improve the performance of the heat exchanger, it is important to ensure a sufficient contact area between the vapor such as the gas-phase refrigerant and the heat transfer tube.

That is, this disclosure
Shell,
A plurality of heat transfer tubes disposed inside the shell;
With
The plurality of heat transfer tubes are arranged in parallel to each other,
Each of the plurality of heat transfer tubes has a curvature radius profile that is smaller than a radius of a circle having the same area as the cross-sectional area of each of the plurality of heat transfer tubes in a vertical cross section perpendicular to the longitudinal direction of each of the plurality of heat transfer tubes. Having a first corner that is a portion indicating
The first corner portion constitutes a lowermost portion of each of the plurality of heat transfer tubes in the vertical direction,
Each of the plurality of heat transfer tubes includes an apex located at the top in the vertical direction,
When the upper heat transfer tube selected from the pair of heat transfer tubes adjacent to each other in the vertical direction is defined as a first heat transfer tube, and the lower heat transfer tube is defined as a second heat transfer tube, the first heat transfer tube is defined. The first corner of the heat pipe is in a position horizontally away from the apex of the second heat transfer pipe,
Each of the plurality of heat transfer tubes has three or more than three portions showing a contour of a radius of curvature smaller than a radius of a circle having the same area as the cross-sectional area of each of the plurality of heat transfer tubes in the longitudinal section. A heat exchanger is provided.

  According to the technology of the present disclosure, a sufficient contact area between steam such as a gas-phase refrigerant and a heat transfer tube can be ensured.

FIG. 1 is a configuration diagram of a refrigeration cycle apparatus according to the first embodiment of the present disclosure. FIG. 2 is a schematic cross-sectional view taken along line II-II of the condenser according to the first embodiment of the present disclosure. FIG. 3 is a partially enlarged view of FIG. FIG. 4 is an enlarged view showing the cross-sectional shape of the heat transfer tube in detail. FIG. 5 is an explanatory diagram of the operation of the condenser according to the first embodiment. FIG. 6 is a cross-sectional view of a heat transfer tube according to a modification. FIG. 7 is a cross-sectional view of a condenser according to another modification. FIG. 8 is a schematic cross-sectional view of a condenser according to the second embodiment of the present disclosure. FIG. 9 is a partially enlarged view of FIG. FIG. 10 is an operation explanatory diagram of the condenser of the second embodiment. FIG. 11A is a schematic diagram showing an outline of an experiment conducted for examining a position where a droplet is detached. FIG. 11B is a graph showing the relationship between the inclination angle of the heat transfer tube and the position at which the droplets are detached. FIG. 12 is a schematic diagram showing the relationship between the droplet drop position and the droplet diameter. FIG. 13 is a graph showing the relationship between the inclination angle of the heat transfer tube and the droplet diameter. FIG. 14 is a schematic diagram illustrating the flow of the liquid in states 1 to 4. FIG. 15 is a graph showing the relationship between the inclination angle of the heat transfer tube and the value (b−Φ). FIG. 16 is a diagram illustrating the relationship between the number of stages of the heat transfer tubes and the thickness of the liquid film on the first heat transfer surface, together with the state of the heat transfer tubes at each stage. FIG. 17 is a graph showing the relationship between the number of stages of the heat transfer tubes and the heat transfer coefficient (ratio to the value of the first step) of the outer peripheral surface of the heat transfer tubes. FIG. 18 is a graph showing the relationship between the inclination angle of the heat transfer tube and the heat transfer coefficient of the outer peripheral surface of the heat transfer tube (ratio to the value of the first stage). FIG. 19 is a cross-sectional view of a condenser according to a modification. FIG. 20 is a cross-sectional view of a condenser according to another modification. FIG. 21 is a schematic cross-sectional view of a conventional shell and tube heat exchanger. FIG. 22 is an operation explanatory diagram of a conventional condenser.

(Knowledge that became the basis of this disclosure)
According to the knowledge of the present inventors, the conventional shell and tube heat exchanger shown in FIG. 21 has the following problems. As shown in FIG. 22, when the refrigerant is introduced into the shell, the refrigerant is cooled on the surface of the heat transfer tube 2a located on the upper side, and a liquid-phase refrigerant is generated. The liquid-phase refrigerant flows down from the bottom of the heat transfer tube 2a and adheres to the top of the heat transfer tube 2b located below the heat transfer tube 2a. Since the liquid phase refrigerant flows along the surface of the heat transfer tube 2b, the surface of the heat transfer tube 2b is entirely covered with the liquid phase refrigerant film. When the surface of the heat transfer tube 2b is entirely covered with a liquid phase refrigerant film, the contact surface between the heat transfer tube 2b and the gas phase refrigerant is lost. As a result, the heat transfer tube 2b cannot sufficiently exhibit the heat transfer performance. The amount of the liquid-phase refrigerant that flows down from the upper heat transfer tube 2a to the lower heat transfer tube 2b gradually increases as the liquid-phase refrigerant moves from the upper side to the lower side. The thickness of the liquid-phase refrigerant film also gradually increases as the liquid-phase refrigerant moves from the upper side to the lower side. If the heat transfer tube 2b cannot exhibit sufficient heat transfer performance, the heat exchanger cannot also exhibit sufficient performance (heat exchange performance).

  According to the above knowledge, if it is possible to prevent the entire surface of the heat transfer tube located on the lower side from being covered with the condensate (liquid phase refrigerant) generated on the surface of the heat transfer tube located on the upper side, Heat transfer performance can be fully demonstrated.

The heat exchanger according to the first aspect of the present disclosure is:
Shell,
A plurality of heat transfer tubes disposed inside the shell;
With
The plurality of heat transfer tubes are arranged in parallel to each other,
Each of the plurality of heat transfer tubes has a curvature radius profile that is smaller than a radius of a circle having the same area as the cross-sectional area of each of the plurality of heat transfer tubes in a vertical cross section perpendicular to the longitudinal direction of each of the plurality of heat transfer tubes. Having a first corner that is a portion indicating
The first corner portion constitutes a lowermost portion of each of the plurality of heat transfer tubes in the vertical direction,
Each of the plurality of heat transfer tubes includes an apex located at the top in the vertical direction,
When the upper heat transfer tube selected from the pair of heat transfer tubes adjacent to each other in the vertical direction is defined as a first heat transfer tube, and the lower heat transfer tube is defined as a second heat transfer tube, the first heat transfer tube is defined. The first corner of the heat pipe is in a position horizontally away from the apex of the second heat transfer pipe,
Each of the plurality of heat transfer tubes has three or more than three portions showing a contour of a radius of curvature smaller than a radius of a circle having the same area as the cross-sectional area of each of the plurality of heat transfer tubes in the longitudinal section. It is to have.
In other words, the first corner of the first heat transfer tube does not overlap the apex of the second heat transfer tube when viewed from the vertical direction.

  When the first heat transfer tube and the second heat transfer tube satisfy the positional relationship as described above, the condensate (liquid phase refrigerant) generated on the surface of the first heat transfer tube can be prevented from flowing down to the top of the second heat transfer tube. . Thereby, it can avoid that the surface of a 2nd heat exchanger tube is entirely covered with a condensed liquid, and the contact surface of a 2nd heat exchanger tube and a vapor | steam is fully ensured. As a result, sufficient heat transfer performance is exhibited also in the second heat transfer tube, and as a result, the heat exchanger can exhibit high performance.

  In the second aspect of the present disclosure, for example, the first corner portion of the heat exchanger according to the first aspect is a portion positioned at one end of each of the plurality of heat transfer tubes in the horizontal direction. Each of the heat transfer tubes further includes a second corner portion that is a portion located at the other end in the horizontal direction, and in the longitudinal section, the first corner portion of the first heat transfer tube and the second heat transfer tube. The first corner portion of the first heat transfer tube exists on a first reference line parallel to the vertical direction, and the second corner portion of the first heat transfer tube and the second corner of the second heat transfer tube. The part exists on a second reference line parallel to the vertical direction. In other words, the first reference line is in contact with the first corner portion of the first heat transfer tube and the second corner portion of the second heat transfer tube, and the second reference line. Are in contact with the second corner of the first heat transfer tube and the second corner of the second heat transfer tube. According to such a configuration, the liquid-phase refrigerant generated on the surface of the heat transfer tube gathers evenly at each of the first corner and the second corner and flows down downward. Since the amount of the liquid phase refrigerant can be equally distributed to the left and right, the liquid phase refrigerant film is thicker than when the liquid phase refrigerant flows downward from only one location of the heat transfer tube. Can be suppressed.

  In the third aspect of the present disclosure, for example, in the longitudinal section of the heat exchanger according to the first or second aspect, the plurality of heat transfer tubes are arranged in a lattice pattern. According to the 3rd aspect, the effect by a 1st aspect can be acquired more fully.

  In the fourth aspect of the present disclosure, for example, in the longitudinal section of the heat exchanger according to the first or second aspect, the plurality of heat transfer tubes are arranged in an alternating pattern. According to such a configuration, the flow direction of the gas-phase refrigerant in the shell becomes irregular, and a strong stirring action acts on the gas-phase refrigerant. As a result, the heat transfer performance of the heat transfer tube can be sufficiently exhibited. When a stirring action acts on the gas-phase refrigerant, the flow of the gas-phase refrigerant can promote the detachment of the liquid-phase refrigerant from the surface of the heat transfer tube. Accordingly, the thickness of the liquid refrigerant film on the surface of the heat transfer tube is reduced, and the heat transfer performance of the heat transfer tube can be sufficiently exhibited.

  In the fifth aspect of the present disclosure, for example, in the longitudinal cross section of the heat exchanger according to any one of the first to fourth aspects, a regular polygon having a minimum area surrounding each of the plurality of heat transfer tubes is provided. It is an equilateral triangle. According to such a shape, a heat exchanger tube can be easily produced by forming a circular tube. Moreover, when the heat transfer tube has a cross-sectional shape that approximates an equilateral triangle, it is easy to earn a horizontal distance between the first corner and the apex.

  In the sixth aspect of the present disclosure, for example, in the longitudinal section of the heat exchanger of the fifth aspect, each bottom surface of the plurality of heat transfer tubes has an inclination angle in a range of 10 to 20 degrees with respect to the horizontal direction. Have. According to the sixth aspect, the liquid-phase refrigerant can flow down from the first corner portion of the first heat transfer tube and contact only one side surface of the second heat transfer tube. That is, the liquid-phase refrigerant can be concentrated on the heat transfer surface having an area of 1/3. Thereby, since the heat transfer performance of the heat transfer tube can be sufficiently exhibited, the refrigerant can be quickly condensed even under a condition where the amount of refrigerant condensed is small, such as during a small load operation.

  In the seventh aspect of the present disclosure, for example, the outline of each of the plurality of heat transfer tubes in the longitudinal section of the heat exchanger according to the fifth aspect is more than the equilateral triangle with the smallest area surrounding the heat transfer tubes. Each of the plurality of heat transfer tubes has a concave portion drawn down toward the inside. According to the seventh aspect, the liquid-phase refrigerant is likely to gather at the corners.

  In the eighth aspect of the present disclosure, for example, in the longitudinal section of the heat exchanger according to any one of the first to seventh aspects, the center of each of the plurality of heat transfer tubes passes through and is parallel to the vertical direction. With respect to the reference line, the contours of the plurality of heat transfer tubes are asymmetric. According to such a configuration, the liquid-phase refrigerant generated on the surface of the heat transfer tube is easily collected at the first corner. It is possible to quickly remove the liquid phase refrigerant from the surface of the heat transfer tube.

  In the ninth aspect of the present disclosure, for example, the first corner of the heat exchanger according to any one of the first to eighth aspects is positioned at one end of each of the plurality of heat transfer tubes in the horizontal direction. Each of the plurality of heat transfer tubes further includes a second corner portion which is a portion located at the other end in the horizontal direction, and the second corner portion is more than the first corner portion. Is also located above in the vertical direction. According to such a configuration, the liquid-phase refrigerant generated on the surface of the heat transfer tube can be easily collected at the first corner and quickly removed from the surface of the heat transfer tube.

  In the tenth aspect of the present disclosure, for example, the inclination angle of the bottom surface of the first heat transfer tube with respect to the horizontal direction of the heat exchanger according to the fifth or sixth aspect is the bottom surface of the second heat transfer tube with respect to the horizontal direction. The inclination direction is equal to the inclination angle, and the inclination direction of the bottom surface of the first heat transfer tube with respect to the horizontal direction is different from the inclination direction of the bottom surface of the second heat transfer tube with respect to the horizontal direction. According to the tenth aspect, since the liquid-phase refrigerant flow is distributed to the left and right, the growth of the liquid film on the first heat transfer surface of the heat transfer tube can be suppressed.

  In the eleventh aspect of the present disclosure, for example, in the longitudinal section of the heat exchanger according to the first aspect, the plurality of heat transfer tubes are arranged in a lattice shape, and in the longitudinal section, each of the plurality of heat transfer tubes is arranged. The regular polygon of the minimum area to enclose is a regular triangle, the bottom surfaces of the plurality of heat transfer tubes are flat surfaces, and the inclination angle of the bottom surface of the first heat transfer tube with respect to the horizontal direction is the horizontal direction. The inclination angle of the bottom surface of the second heat transfer tube with respect to the horizontal direction is different from the inclination direction of the bottom surface of the second heat transfer tube with respect to the horizontal direction, The positions of the first corners of the plurality of heat transfer tubes located in odd stages in the vertical direction are aligned with each other in the horizontal direction, and the first of the heat transfer tubes located in even stages in the vertical direction. Corners of the in the horizontal direction is located between the apex and the first corner of the heat transfer tubes positioned in the odd-numbered stage. According to the eleventh aspect, it is possible to more reliably eliminate the influence of the liquid-phase refrigerant flowing down from the upper heat transfer tube to the lower heat transfer tube.

A refrigeration cycle apparatus according to a twelfth aspect of the present disclosure is provided.
An evaporator for heating the refrigerant;
A compressor for compressing the refrigerant;
The condenser for condensing the refrigerant;
With
The condenser is configured by any one of the first to eleventh heat exchangers.

  According to the 12th aspect, the refrigerating-cycle apparatus which can exhibit the outstanding COP (coefficient of performance) can be provided. In particular, a high effect is obtained when the refrigeration cycle apparatus is operated under the condition that the flow rate (mass flow rate) of the refrigerant increases.

  Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments.

(First embodiment)
As shown in FIG. 1, the refrigeration cycle apparatus 10 includes an evaporator 11, a compressor 12, a condenser 13, a flow rate control valve 14, and flow paths 16a to 16d. The outlet of the evaporator 11 is connected to the suction port of the compressor 12 by a flow path 16a. The discharge port of the compressor 12 is connected to the inlet of the condenser 13 by the flow path 16b. The outlet of the condenser 13 is connected to the inlet of the flow control valve 14 by a flow path 16c. The outlet of the flow control valve 14 is connected to the inlet of the evaporator 11 by a flow path 16d. The flow paths 16a and 16b are vapor paths, and the flow paths 16c and 16d are liquid paths. Each flow path is composed of, for example, at least one metal pipe.

  In the evaporator 11, the refrigerant is heated and evaporated. Thereby, a gas-phase refrigerant (refrigerant vapor) is generated. The gas-phase refrigerant is sucked into the compressor 12 and compressed. A high-temperature and high-pressure gas-phase refrigerant is supplied from the compressor 12 to the condenser 13. The refrigerant is cooled and liquefied in the condenser 13. Thereby, a liquid phase refrigerant (refrigerant liquid) is generated. The liquid phase refrigerant is returned from the condenser 13 to the evaporator 11 via the flow control valve 14.

  The refrigeration cycle apparatus 10 is an air conditioner for business use or home use, for example. The heat medium cooled by the evaporator 11 is supplied into the room and used for cooling the room. Or the heat medium heated with the condenser 13 is supplied indoors, and is used for indoor heating. The heat medium is, for example, water. However, the refrigeration cycle apparatus 10 is not limited to an air conditioner, and may be another apparatus such as a chiller or a heat storage device.

  As shown in FIG. 2, the condenser 13 is constituted by a shell and tube heat exchanger. Specifically, the condenser 13 includes a shell 20 and a plurality of heat transfer tubes 30. The plurality of heat transfer tubes 30 are arranged inside the shell 20. The shell 20 has an inlet 20a and an outlet 20b. A channel 16b and a channel 16c can be connected to the inlet 20a and the outlet 20b, respectively. In the vertical direction, the inlet 20a of the shell 20 is located at the top, and the outlet 20b of the shell 20 is located at the bottom. For example, the inlet 20 a is positioned above the heat transfer tubes 30 in the vertical direction, and the outlet 20 b is positioned below the heat transfer tubes 30 in the vertical direction. A gas phase refrigerant is introduced into the shell 20 through the inlet 20a. When a heat medium having a temperature lower than the temperature of the refrigerant is passed through the heat transfer tube 30, the refrigerant is cooled and condensed on the surface of the heat transfer tube 30. The liquid-phase refrigerant is discharged to the outside of the shell 20 through the outlet 20b. In the present embodiment, the shell 20 has a rectangular cross-sectional shape. However, the shell 20 may have a circular cross-sectional shape. The shell 20 may be a pressure vessel.

  Each of the plurality of heat transfer tubes 30 has a linear shape. The plurality of heat transfer tubes 30 are arranged in parallel with each other inside the shell 20. Headers (not shown) are provided at both ends of the plurality of heat transfer tubes 30, respectively. The heat medium is distributed from the header to each heat transfer tube 30, and the heat medium is collected from each heat transfer tube 30 to the header.

  FIG. 2 shows a cross section of the condenser 13 perpendicular to the longitudinal direction of the heat transfer tube 30. Hereinafter, in the present disclosure, a cross section perpendicular to the longitudinal direction of the heat transfer tube 30 is referred to as a “longitudinal cross section”. In the present embodiment, the longitudinal section is parallel to the vertical direction. Except for both ends of the heat transfer tube 30, the cross-sectional shape of the heat transfer tube 30 is the same at any position in the longitudinal direction. When the direction (first direction) parallel to the longitudinal direction of the heat transfer tube 30 is the Z direction, the vertical direction (second direction perpendicular to the first direction) is the Y direction, and the horizontal direction (first direction) Direction and a third direction perpendicular to the second direction) is the X direction.

  In the longitudinal section shown in FIG. 2, the plurality of heat transfer tubes 30 are arranged side by side in a lattice pattern. When a plurality of vertical reference lines Vr parallel to the vertical direction and a plurality of horizontal reference lines Hr parallel to the horizontal direction are defined, above each intersection of the plurality of vertical reference lines Vr and the plurality of horizontal reference lines Hr In addition, the heat transfer tube 30 (specifically, the center of gravity G of the heat transfer tube 30) is located. The plurality of vertical reference lines Vr are arranged at equal intervals. A plurality of horizontal reference lines Vr are also arranged at equal intervals. The plurality of heat transfer tubes 30 are arranged in a matrix in the vertical direction (longitudinal direction) and the horizontal direction (lateral direction). Between the heat transfer tubes 30 adjacent to each other in the horizontal direction, a moderately wide space is secured as a refrigerant flow path. Similarly, a moderately wide space is secured between the heat transfer tubes 30 adjacent to each other in the vertical direction as a refrigerant flow path.

  As shown in FIG. 3, the heat transfer tube 30 (30A, 30B) has a non-circular cross-sectional shape. Specifically, each heat transfer tube 30 has a corner portion 31 (also referred to as “first corner portion 31”). The corner portion 31 is a portion showing a contour having a radius of curvature smaller than the radius of a circle having the same area as the cross-sectional area of the heat transfer tube 30 in the longitudinal section. Moreover, the corner | angular part 31 comprises the part located in the lowest part of the heat exchanger tube 30 in a perpendicular direction.

  As shown in FIG. 3, each heat transfer tube 30 includes an apex 33 p located at the top in the vertical direction. The upper heat transfer tube 30 selected from a pair of heat transfer tubes 30 adjacent to each other in the vertical direction is defined as a first heat transfer tube 30A, and the lower heat transfer tube 30 is defined as a second heat transfer tube 30B. The first heat transfer tube 30A and the second heat transfer tube 30B are located on a common vertical reference line Vr. The corner portion 31 of the first heat transfer tube 30A is at a position away from the apex 33p of the second heat transfer tube 30B in the horizontal direction. When the first heat transfer tube 30A and the second heat transfer tube 30B satisfy such a positional relationship, the liquid-phase refrigerant generated on the surface of the first heat transfer tube 30A is separated from the apex 33p of the second heat transfer tube 30B in the horizontal direction. Gather at the same position and flow downwards. That is, it is possible to avoid the liquid refrigerant generated on the surface of the first heat transfer tube 30A from flowing down to the apex 33p of the second heat transfer tube 30B. Thereby, it can avoid that the surface of the 2nd heat exchanger tube 30B is entirely covered with a liquid phase refrigerant | coolant, and the contact surface of the 2nd heat exchanger tube 30B and a gaseous-phase refrigerant | coolant is fully ensured. As a result, sufficient heat transfer performance is exhibited also in the second heat transfer tube 30B, and as a result, the performance of the condenser 13 is sufficiently exhibited.

  As shown in FIG. 3, the heat transfer tube 30 further includes another corner portion 32 (also referred to as “second corner portion 32”) and a top portion 33 in addition to the first corner portion 31. The first corner portion 31 is a portion located at one end in the horizontal direction. The 2nd corner | angular part 32 is a part located in the other end in a horizontal direction. Not only the first corner portion 31 but also the second corner portion 32 constitutes a portion located at the bottom of the heat transfer tube 30 in the vertical direction. That is, the first corner portion 31 is located at the same height as the second corner portion 32 in the vertical direction. The top portion 33 is a portion located on the top of the heat transfer tube 30 in the vertical direction. The vertex 33p is a position included in the top 33. In the longitudinal section, the first corner portion 31 of the first heat transfer tube 30A and the first corner portion 31 of the second heat transfer tube 30B are present on the first reference line V1 parallel to the vertical direction. In the longitudinal section, the second corner portion 32 of the first heat transfer tube 30A and the second corner portion 32 of the second heat transfer tube 30B exist on the second reference line V2 parallel to the vertical direction. The distance D between the first reference line V1 and the second reference line V2 is equal to the dimension (width) of the heat transfer tube 30 in the horizontal direction. That is, in this embodiment, the cross-sectional shape of the heat transfer tube 30 is symmetric with respect to the vertical reference line Vr. According to such a configuration, the liquid-phase refrigerant generated on the surface of the heat transfer tube 30 gathers evenly at each of the first corner portion 31 and the second corner portion 32 and flows down downward. Since the amount of the liquid-phase refrigerant can be equally distributed to the left and right, the liquid-phase refrigerant film is thicker than when the liquid-phase refrigerant flows downward from only one location of the heat transfer tube 30. Can be suppressed. Moreover, since the position of the 1st corner | angular part 31 and the position of the 2nd corner | angular part 32 are aligned regarding the perpendicular direction, the liquid-phase refrigerant | coolant which arose on the surface of the 1st heat exchanger tube 30A is the corner | angular of the 2nd heat exchanger tube 30B. It can be generally avoided that it flows down to portions other than the portions 31 and 32. Therefore, the area of the surface of the second heat transfer tube 30B covered with the liquid-phase refrigerant generated on the surface of the first heat transfer tube 30A can be minimized.

  The “first corner portion 31”, the “second corner portion 32”, and the “top portion 33” can also be defined as follows. A portion showing an arcuate contour having a radius of curvature smaller than the radius of a circle having the same area as the cross-sectional area of the heat transfer tube 30 in the vertical cross section is defined as “corner”. The “corner” positioned at the top in the vertical direction can be defined as the “top”. According to this embodiment, the 1st corner | angular part 31, the 2nd corner | angular part 32, and the top part 33 all show the circular-arc outline of the same curvature radius in a longitudinal cross section.

  According to the present embodiment, the heat transfer tube 30 has three or three portions (corner portions) showing contours of a radius of curvature smaller than the radius of a circle having the same area as the cross-sectional area of the heat transfer tube 30 in the longitudinal section. Have beyond. Specifically, in the longitudinal section, a regular polygon having a minimum area surrounding the heat transfer tube 30 is a regular triangle. According to such a shape, the heat exchanger tube 30 of this embodiment can be easily produced by forming a circular tube. Further, when the heat transfer tube 30 has a cross-sectional shape that approximates an equilateral triangle, it is easy to earn a horizontal distance between the first corner portion 31 and the apex 33p. However, the triangle with the smallest area surrounding the heat transfer tube 30 is not limited to an equilateral triangle, and may be an isosceles triangle, a right triangle, or an unequal triangle. Furthermore, the rectangle with the smallest area surrounding the heat transfer tube 30 may be a rectangle, a square, a rhombus, or an unequal side rectangle. The upper limit of the number of corners is not particularly limited, but is 6 for example in consideration of ease of molding.

  According to this embodiment, the outline of the heat transfer tube 30 in the longitudinal section is composed of a plurality (three) of curved portions and a plurality (three) of straight portions. The plurality of curved portions correspond to the first corner portion 31, the second corner portion 32, and the top portion 33, respectively. The plurality of straight line portions are located between the curved portion and the curved portion, respectively. Of course, the outline of the heat transfer tube 30 may be formed of a smooth curve except for portions corresponding to the first corner portion 31, the second corner portion 32, and the top portion 33.

  As shown in FIG. 4, the contour of the heat transfer tube 30 in the longitudinal section is a concave portion 30p, 30q that is pulled down toward the inside of the heat transfer tube 30 from the equilateral triangle 40 having the smallest area that virtually surrounds the heat transfer tube 30. And 30r. The concave portions 30p, 30q, and 30r face the sides of the regular triangle 40, respectively. The concave portion 30 p is a portion between the first corner portion 31 and the second corner portion 32. The concave portion 30q is a portion between the first corner portion 31 and the top portion 33. The concave portion 30 r is a portion between the second corner portion 32 and the top portion 33. The concave portion 30p is a portion corresponding to the bottom surface of the heat transfer tube 30, and is inclined with respect to the horizontal plane. The inclination angle θ of the concave portion 30p with respect to the horizontal plane is, for example, in the range of 1 to 5 degrees. The outline of the heat transfer tube 30 has the same concave shape on three sides. That is, the outline of the heat transfer tube 30 in the longitudinal section has rotational symmetry with respect to the center of gravity G (for example, three-fold rotational symmetry). According to such a configuration, the heat transfer tube 30 of this embodiment can be easily manufactured by forming a circular tube. Since the heat transfer tube 30 has no directionality, it is very easy to assemble a large number of heat transfer tubes 30 on a header or the like. That is, it is easy to manufacture the condenser 13 (heat exchanger) using the heat transfer tube 30.

  In addition, since the bottom surface of the heat transfer tube 30 between the first corner portion 31 and the second corner portion 32 is formed in a concave shape upward, the liquid-phase refrigerant can be used in the first corner portion 31 or the first corner portion 31. It is easy to gather at the two corners 32. As a result, it is possible to continuously ensure contact between the bottom surface of the heat transfer tube 30 and the gas-phase refrigerant.

  Next, the operation of the condenser 13 will be described in detail with reference to FIG.

  When the gas-phase refrigerant is introduced into the shell 20, a part of the refrigerant is cooled by the heat medium flowing through the first heat transfer tube 30A and condensed on the surface of the first heat transfer tube 30A. The liquid-phase refrigerant generated on the surface of the first heat transfer tube 30A flows along the surface of the first heat transfer tube 30A and collects at the corners 31 and 32. Thereafter, the liquid-phase refrigerant flows down from the top 33 of the second heat transfer tube 30B to a position shifted in the horizontal direction. Specifically, the liquid-phase refrigerant flows down from the corners 31 and 32 of the first heat transfer tube 30A to the vicinity of the surfaces of the corners 31 and 32 of the second heat transfer tube 30B, and the corners 31 and 32 of the second heat transfer tube 30B. Will flow down further down. That is, most of the liquid-phase refrigerant flows down near the corners 31 and 32 of the heat transfer tube 30 by its own weight, and is quickly removed from the surface of the heat transfer tube 30. Therefore, even when the heat transfer tubes 30 are arranged in a matrix, a sufficient contact area between the gas-phase refrigerant and the surface of the second heat transfer tube 30B can be secured. According to the present embodiment, the heat transfer performance of the heat transfer tube 30 can be sufficiently exhibited, so that the performance of the condenser 13 can be improved without increasing the number of heat transfer tubes 30, the surface area, and the like. Further, the bottom surface of the heat transfer tube 30 between the first corner portion 31 and the second corner portion 32 is formed in a concave shape upward. This configuration also contributes to securing a contact area between the gas-phase refrigerant and the surface of the heat transfer tube 30.

  Moreover, according to this embodiment, the following effects are also acquired. The gas-phase refrigerant introduced into the shell 20 is cooled by the heat medium inside the heat transfer tube 30. In the sensible heat change region, the density of the gas-phase refrigerant increases, so that a flow of the gas-phase refrigerant directed downward in the vertical direction is formed inside the shell 20.

  As shown in FIG. 22, in the condenser using the heat transfer tube 2 having a circular cross section, the flow of the gas-phase refrigerant is separated from the surface of the heat transfer tube 2 and stagnation occurs. At this time, buoyancy acts on the liquid-phase refrigerant collected near the bottom of the heat transfer tube 2. As a result, free fall of the liquid phase refrigerant from the heat transfer tube 2 is prevented.

  On the other hand, according to the present embodiment, such buoyancy is unlikely to act on the liquid-phase refrigerant collected at the corners 31 and 32. Therefore, the liquid phase refrigerant can smoothly flow downward from the corners 31 and 32 due to its own weight.

(Modification)
In the heat transfer tube 30c shown in FIG. 6, the surface between the first corner portion 31 and the second corner portion 32 is formed in a concave shape upward in the vertical direction. On the other hand, the surface between the top 33 and the first corner 31 is a flat surface inclined at an inclination angle β (for example, 60 degrees) with respect to the horizontal plane. The surface of the heat transfer tube 30c between the top 33 and the second corner 32 is also a flat surface that is inclined at an inclination angle β with respect to the horizontal plane. Even when only the bottom surface of the heat transfer tube 30c is formed in a concave shape upward as in the present modification, it is possible to prevent the liquid-phase refrigerant from staying on the bottom surface. Further, since the side surface inclination angle β can be increased as compared with the heat transfer tube 30 described with reference to FIG. 3, the liquid phase refrigerant can be quickly removed from the surface (side surface) of the heat transfer tube 30 c.

  As shown in FIG. 7, the difference between the condenser 23 according to another modification and the condenser 13 shown in FIG. 2 is the arrangement of the plurality of heat transfer tubes 30. According to this modification, in the longitudinal section of the condenser 23, the plurality of heat transfer tubes 30 are arranged in an alternating pattern. Also in this modification, the some heat exchanger tube 30 is located on each vertical reference line Vr. The position of the heat transfer tube 30 on one side of the vertical reference lines Vr adjacent to each other is shifted in the vertical direction from the position of the heat transfer tube 30 on the other side. Further, even if the heat transfer tubes 30 positioned on one of the adjacent vertical reference lines Vr are translated in the vertical direction, they do not overlap with the heat transfer tubes 30 positioned on the other of the adjacent vertical reference lines Vr. In addition, the interval between adjacent vertical reference lines Vr is adjusted. Similarly, the plurality of heat transfer tubes 30 are located on each horizontal reference line Hr. The position of the heat transfer tube 30 on one side of the horizontal reference lines Hr adjacent to each other is shifted in the horizontal direction from the position of the heat transfer tube 30 on the other side. Moreover, even if the heat transfer tubes 30 positioned on one of the adjacent horizontal reference lines Hr are translated in the horizontal direction, they do not overlap with the heat transfer tubes 30 positioned on the other of the adjacent horizontal reference lines Hr. Further, the interval between the horizontal reference lines Hr adjacent to each other is adjusted. For example, the interval between adjacent vertical reference lines Vr is equal to the interval between adjacent horizontal reference lines Hr. According to such a configuration, it is possible to achieve more efficient heat exchange.

  In the condenser 23, the shape of the flow path formed around the plurality of heat transfer tubes 30 is asymmetric with respect to at least one of the vertical direction and the horizontal direction. In this modification, the shape of the flow path inside the shell 20 of the condenser 23 is asymmetric with respect to the vertical direction. Specifically, in the longitudinal section, a flow path inside the shell 20 surrounded by three vertical reference lines Vr adjacent to each other and three horizontal reference lines Hr adjacent to each other is defined as a specific flow path. The specific flow path is symmetric with respect to the middle vertical reference line Vr selected from the three vertical reference lines Vr. On the other hand, the specific flow path is asymmetric with respect to the middle horizontal reference line Hr selected from the three horizontal reference lines Hr.

  According to the condenser 23 of this modification, the following effects can be obtained. First, according to this modification, the flow direction of the gas-phase refrigerant in the shell 20 becomes irregular, and a strong stirring action acts on the gas-phase refrigerant. As a result, the heat transfer performance of the heat transfer tube 30 can be sufficiently exhibited. In addition, the gas phase refrigerant is positive around the first corner portion 31 and the second corner portion 32 by combining the stir action acting on the gas phase refrigerant, the shape of the heat transfer tube 30, and the alternating pattern. Flowing. Further, separation of the liquid phase refrigerant from the first corner portion 31 and the second corner portion 32 is promoted, and the thickness of the liquid phase refrigerant film covering the surface of the heat transfer tube 30 is also reduced. As a result, the heat transfer performance of the heat transfer tube 30 can be more fully exhibited.

(Second Embodiment)
As shown in FIGS. 8 and 9, in the condenser 43 according to the present embodiment, a plurality of heat transfer tubes 30 d are used instead of the heat transfer tubes 30 described above. Other configurations of the condenser 43 are as described in the first embodiment. Also in the present embodiment, the upper heat transfer tube 30d selected from the set of heat transfer tubes 30d adjacent to each other in the vertical direction is defined as the first heat transfer tube 30A, and the lower heat transfer tube 30d is defined as the second heat transfer tube 30B. To do. The first heat transfer tube 30A and the second heat transfer tube 30B are located on a common vertical reference line Vr. The corner portion 31 of the first heat transfer tube 30A is at a position away from the apex 33p of the second heat transfer tube 30B in the horizontal direction. Therefore, also in this embodiment, the same effect as that described in the first embodiment can be obtained.

  The heat transfer tube 30 d has a first corner portion 31, a second corner portion 32, and a top portion 33. The heat transfer tube 30d has a plurality of (three) surfaces. One of the plurality of surfaces is a surface 34 (side surface) between the first corner portion 31 and the top portion 33. Another one of the plurality of surfaces is a surface 36 (bottom surface 36) between the first corner portion 31 and the second corner portion 32. Another one of the plurality of surfaces is a surface 35 (side surface) between the second corner portion 32 and the top portion 33. These plural surfaces are all flat surfaces. That is, the heat transfer tube 30d has no recess. It is not essential that the portions excluding the first corner portion 31, the second corner portion 32, and the top portion 33 are formed in a concave shape. Such a heat transfer tube 30d can be easily manufactured. Further, since the heat transfer tube 30d has no directionality, it is very easy to assemble a large number of heat transfer tubes 30d on a header or the like. That is, it is easy to manufacture the condenser 43 using the heat transfer tube 30d. Furthermore, since the stress is less likely to concentrate on a specific portion of the heat transfer tube 30d, the heat transfer tube 30d is also excellent in pressure resistance.

  In this embodiment, the 1st corner | angular part 31 of the heat exchanger tube 30d is a part located in the lowest part of the heat exchanger tube 30d in a perpendicular direction. On the other hand, the second corner portion 32 of the heat transfer tube 30d is not the lowest portion of the heat transfer tube 30d in the vertical direction. In the vertical direction, the second corner 32 is located at a different height from the first corner 31. Specifically, the second corner portion 32 is located above the first corner portion 31 in the vertical direction. In the vertical direction, the second corner portion 32 is located between the top portion 33 and the first corner portion 31. The surface 36 (bottom surface 36) between the first corner portion 31 and the second corner portion 32 is inclined at an inclination angle θ with respect to the horizontal plane. The inclination angle θ is, for example, in the range of 1 to 29 degrees. The surface 34 (side surface) between the first corner portion 31 and the top portion 33 is also inclined at an inclination angle β with respect to the horizontal plane. The inclination angle β is, for example, (θ + 60) degrees. In the longitudinal section, the outline of the heat transfer tube 30d is asymmetric with respect to a reference line Vr (vertical reference line) passing through the center of gravity G of the heat transfer tube 30d and parallel to the vertical direction. According to such a configuration, the liquid-phase refrigerant generated on the surface of the heat transfer tube 30 d is easily collected in the first corner portion 31. Similar to the heat transfer tube 30c described with reference to FIG. 6, it is possible to quickly remove the liquid-phase refrigerant from the surface of the heat transfer tube 30d.

  Also in the present embodiment, the regular polygon having the smallest area surrounding each of the plurality of heat transfer tubes 30d is an equilateral triangle. Each bottom surface 36 of the plurality of heat transfer tubes 30d is a flat surface and is inclined in the range of 10 to 20 degrees with respect to the horizontal direction (X direction). In other words, the angle θ formed by the bottom surface 36 and a plane parallel to the horizontal direction is in the range of 10 to 20 degrees.

  In the present embodiment, of the three surfaces 34, 35, and 36 of the heat transfer tube 30d, the surface 34 having the largest inclination angle β with respect to the virtual horizontal plane is also referred to as a first heat transfer surface 34. The surface 35 facing the first corner portion 31 is also referred to as a second heat transfer surface 35. The bottom surface 36 facing the top portion 33 is also referred to as a third heat transfer surface 36. The inclination angle (60−θ) of the second heat transfer surface 35 with respect to the horizontal plane is smaller than the inclination angle β of the first heat transfer surface 34 with respect to the horizontal plane and greater than the inclination angle θ of the third heat transfer surface 36 with respect to the horizontal plane.

  As shown in FIG. 10, the liquid-phase refrigerant generated on the first heat transfer surface 34 moves toward the first corner portion 31. The liquid phase refrigerant generated on the second heat transfer surface 35 moves toward the first corner portion 31 via the third heat transfer surface 36 (bottom surface). The liquid-phase refrigerant generated on the third heat transfer surface 36 also moves toward the first corner portion 31. When the inclination angle θ of the third heat transfer surface 36 with respect to the horizontal plane is sufficiently large (for example, θ = 25 degrees), the liquid-phase refrigerant is smoothly collected at the first corner portion 31. When the inclination angle θ of the third heat transfer surface 36 with respect to the horizontal plane is relatively small (for example, θ = 5 degrees), the liquid-phase refrigerant is detached from the third heat transfer surface 36 before collecting at the first corner portion 31. To do. That is, the liquid phase refrigerant flows down from the upper heat transfer tube 30d (first heat transfer tube 30A) to the first heat transfer surface 34 of the lower heat transfer tube 30d (second heat transfer tube 30B), and the first heat transfer surface 34 and Contact with the gas phase refrigerant is impeded. Therefore, it can be said that it is desirable that the inclination angle θ of the third heat transfer surface 36 with respect to the horizontal plane is appropriately secured.

  The inventors investigated the relationship between the inclination angle θ of the third heat transfer surface 36 with respect to the horizontal plane and the position where the liquid-phase refrigerant is detached by simulation. Specifically, as shown in FIG. 11A, the separation position of the droplet W from the heat transfer tube 30d was examined while changing the inclination angle θ of the third heat transfer surface 36 (bottom surface) with respect to the horizontal plane. The droplet W was dropped on the second heat transfer surface 35. The separation position of the droplet W from the heat transfer tube 30d was specified, and the distance d in the horizontal direction between the gravity center of the droplet W and the gravity center of the heat transfer tube 30d at the separation position was recorded. The diameter of the heat transfer tube 30d (diameter of the circumscribed circle of the cross section of the heat transfer tube 30d) was 16 mm. The droplet W was water. The result is shown in FIG. 11B.

  As shown in FIG. 11B, when the inclination angle θ is smaller than 10 degrees, the droplet W detached from the heat transfer tube 30d before reaching the first corner portion 31 of the heat transfer tube 30d. When the inclination angle θ was 10 degrees or more, the droplet W reached the first corner portion 31 and detached from the first corner portion 31. This result indicates that the inclination angle θ of the third heat transfer surface 36 (bottom surface) with respect to the horizontal plane is desirably 10 degrees or more.

  Next, the diameter φ of the droplet W when the droplet W separated from the heat transfer tube 30d was examined by experiment while changing the inclination angle θ. Specifically, as shown in FIG. 12, a liquid (water) is dropped little by little on the top portion 33p of the heat transfer tube 30d, and the droplet W at the moment of separation from the heat transfer tube 30d is photographed with a camera, and its diameter φ (horizontal The largest dimension in direction) was recorded. The results are shown in FIG. As the tilt angle θ increased, the diameter φ of the droplet W decreased.

  As shown in FIG. 12, the distance b in the horizontal direction between the first reference line V1 in contact with the first corner portion 31 and the apex 33p is the length a of the first heat transfer surface 34 in the longitudinal section. It is represented by the following formula (1). When the droplet W is detached from the first heat transfer tube 30A, the drop position of the droplet W on the surface of the second heat transfer tube 30B also depends on the relationship between the distance b, the diameter φ of the droplet W, and the inclination angle θ. Change.

  b = a · cos (60 + θ) (1)

  As shown in FIG. 14, when the distance b is larger than the diameter φ of the droplet W and the inclination angle θ is smaller than 10 degrees (state 1), the drop position of the droplet W approaches the center of gravity G of the heat transfer tube 30d. Move in the direction you want. Therefore, the droplet W dropped from the first heat transfer tube 30A flows through all the heat transfer surfaces of the second heat transfer tube 30B. When the distance b is larger than the diameter φ of the droplet W and the inclination angle θ is 10 degrees or more (state 2), the droplet W flows through a part of the first heat transfer surface 34. When the distance b is equal to the diameter φ of the droplet W and the inclination angle θ is 10 degrees or more (state 3), the droplet W flows only through the first heat transfer surface 34. When the distance b is smaller than the diameter φ of the droplet W and the inclination angle θ is 10 degrees or more (state 4), the droplet W falls on the vertex 33p and flows on all the heat transfer surfaces.

  Next, for each of the heat transfer tubes 30d having diameters Φ of 12.7 mm, 16.0 mm, and 19.05 mm, the relationship between the inclination angle θ and the value (b−Φ) was examined by simulation. The results are shown in FIG. The “diameter Φ of the heat transfer tube 30d” means the diameter of the smallest circle circumscribing the heat transfer tube 30d in the longitudinal section.

  As shown in FIG. 15, the smaller the diameter Φ of the heat transfer tube 30d, the maximum value of the inclination angle θ that can take the state 3, that is, the inclination angle when the droplet W flows only through the first heat transfer surface 34. The maximum value of θ was small. The greater the diameter Φ of the heat transfer tube 30d, the greater the maximum value of the inclination angle θ that can assume the state 3.

  As shown in FIG. 16, when the droplet W flows only on the first heat transfer surface 34 (state 3), the thickness of the liquid film WF on the first heat transfer surface 34 is the number of stages of the heat transfer tube 30d in the evaporator 43. As it increases, it increases at an accelerated rate. In FIG. 16, “the thickness of the liquid film WF on the first heat transfer surface” is represented by a thickness that is an integral multiple of the reference value, with the thickness of the liquid film WF for one layer as a reference value. “The number of stages of the heat transfer tubes 30d” represents the number of heat transfer tubes 30d located on the same vertical reference line Vr. The uppermost step in the vertical direction is the first step.

  As shown in FIG. 16, the liquid-phase refrigerant is accumulated only on the first heat transfer surface 34, and the liquid film WF grows on the first heat transfer surface 34. Although liquid phase refrigerant is also generated on the second heat transfer surface 35 and the third heat transfer surface 36, liquid phase refrigerant is not accumulated on the second heat transfer surface 35 and the third heat transfer surface 36, and the second heat transfer surface 36. The hot surface 35 and the third heat transfer surface 36 are always kept in a fresh state (a state not covered with a thick liquid film). As described above, according to the present embodiment, the thickness of the liquid film WF increases at the first heat transfer surface 34 as the number of stages of the heat transfer tubes 30d increases. When the uppermost step in the vertical direction is the first step, the heat transfer performance of the first heat transfer surface 34 of the heat transfer tube 30d located in the nth step (n is an integer) is a condensation using a circular tube. This corresponds to the heat transfer performance of the (3n-2) stage heat transfer tube of the vessel. The heat transfer performance of the second heat transfer surface 35 and the third heat transfer surface 36 does not depend on the increase in the number of stages of the heat transfer tubes 30d, and is always equal to the heat transfer performance when n = 1 (first stage). The relationship between the number of stages of the heat transfer tube 30d and the heat transfer coefficient of the outer peripheral surface (each heat transfer surface) of the heat transfer tube 30d was examined by simulation. The results are shown in FIG.

  In FIG. 17, the horizontal axis represents the number of stages of the heat transfer tube 30d. The vertical axis represents the ratio of the heat transfer coefficient of the outer peripheral surface (each heat transfer surface) of the nth heat transfer tube 30d to the heat transfer coefficient of the outer peripheral surface (each heat transfer surface) of the first heat transfer tube 30d. ing. In FIG. 17, in addition to the heat transfer coefficients of the first heat transfer surface 34, the second heat transfer surface 35, and the third heat transfer surface 35, the average value and the value of the circular tube are shown. According to the condenser 43 of the present embodiment, the heat transfer coefficient of the first heat transfer surface 34 is lower than the heat transfer coefficient of the surface of the circular tube in all the stages after the second stage. However, the second heat transfer surface 35 and the third heat transfer surface 36 exceeded the heat transfer coefficient of the surface of the circular tube in all the steps after the second step. The average value of the heat transfer coefficient of the first heat transfer surface 34, the second heat transfer surface 35, and the third heat transfer surface 35 exceeded the heat transfer coefficient of the surface of the circular tube in all the stages after the second stage.

  Next, the relationship between the inclination angle θ and the heat transfer coefficient of the outer peripheral surface of the heat transfer tube 30d (the average value of the three surfaces) of the heat transfer tube 30d located at the 10th stage was examined by simulation. The simulation was performed for each of the condensers using the heat transfer tube 30d having diameters Φ of 12.7 mm, 16.0 mm, and 19.05 mm. The results are shown in FIG. As can be understood from FIG. 18, in the state 2 or the state 3, the heat transfer tube 30d showed an excellent heat transfer coefficient. With respect to the heat transfer tube 30d having a diameter Φ of 12.7 to 19.05 mm, when the inclination angle θ is in the range of 10 to 20 degrees, the condenser 43 exhibits better heat exchange performance. It can be said that the inclination angle θ of the bottom surface 36 (third heat transfer surface) of the heat transfer tube 30d with respect to the horizontal plane is desirably 10 to 20 degrees.

(Modification)
As shown in FIG. 19, it is not essential that the inclination directions of all the heat transfer tubes 30d coincide. In the condenser 53 shown in FIG. 19, the inclination angle θ of the bottom surface of the first heat transfer tube 30A with respect to the horizontal direction is equal to the inclination angle θ of the bottom surface of the second heat transfer tube 30B with respect to the horizontal direction. However, the inclination direction of the bottom surface of the first heat transfer tube 30A with respect to the horizontal direction is different from the inclination direction of the bottom surface of the second heat transfer tube 30B with respect to the horizontal direction. The bottom surface of the first heat transfer tube 30A is inclined in a direction opposite to the inclination direction of the bottom surface of the second heat transfer tube 30B. The first corner portion 31 of the first heat transfer tube 30A is on one side in the horizontal direction, whereas the first corner portion 31 of the second heat transfer tube 30B is on the other side in the horizontal direction. If the inclination angle θ of the bottom surface of the first heat transfer tube 30A with respect to the horizontal plane is a positive value, the inclination angle θ of the bottom surface of the second heat transfer tube 30B with respect to the horizontal plane is a negative value. Regarding the horizontal direction, the position of the first corner portion 31 of the first heat transfer tube 30A coincides with the position of the second corner portion 32 of the second heat transfer tube 30B. The position of the second corner portion 32 of the first heat transfer tube 30A coincides with the position of the first corner portion 31 of the second heat transfer tube 30B. In other words, in the longitudinal section, the first corner portion 31 of the first heat transfer tube 30A and the second corner portion 32 of the second heat transfer tube 30B exist on the first reference line V1 parallel to the vertical direction. . In the longitudinal section, the second corner portion 32 of the first heat transfer tube 30A and the first corner portion 31 of the second heat transfer tube 30B exist on the second reference line V2 parallel to the vertical direction. The reference lines V1 and V2 are as described in the first embodiment.

  According to the condenser 53 shown in FIG. 19, the growth of the liquid film can be further suppressed. That is, the liquid-phase refrigerant is separated from the first corner portion 31 of the first heat transfer tube 30A, passes through the second corner portion 32 of the second heat transfer tube 30B, and is below the second heat transfer tube 30B. It reaches the first heat transfer surface 34 of the heat transfer tube 30d (having the same arrangement as the first heat transfer tube). The liquid-phase refrigerant is separated from the first corner portion 31 of the second heat transfer tube 30B, passes through the second corner portion 32 of the first heat transfer tube 30A, and is below the first heat transfer tube 30A. It reaches the first heat transfer surface 34 of the heat transfer tube 30d (having the same arrangement as the second heat transfer tube). Thus, according to this modification, the flow of the liquid-phase refrigerant is distributed to the left and right, so that the growth of the liquid film on the first heat transfer surface 34 of the heat transfer tube 30d can be suppressed. As a result, the heat transfer coefficient (average value) of the heat transfer tube 30d is further improved as compared with the circular tube.

  Further, according to the present modification, the shape of the flow path of the gas-phase refrigerant (the space between the adjacent heat transfer tubes 30d) is complicated, and the separation of the gas-phase refrigerant from the surface of the heat transfer tubes 30d is suppressed, The detachment of the liquid refrigerant from the surface of the heat transfer tube 30d is promoted. When the liquid-phase refrigerant is separated from the first heat transfer tube 30A, the re-contact of the liquid-phase refrigerant with the heat transfer surface of the second heat transfer tube 30B can be minimized. Therefore, the heat transfer performance of the heat transfer tube 30d can be sufficiently exerted even in an overload condition where the flow rate of the refrigerant is large. Since the width of the flow path of the gas phase refrigerant is also made uniform, pressure loss due to the shape of the flow path is also reduced. As the pressure loss is reduced, the condensing pressure decreases, so further improvement in heat transfer performance can be expected.

  Furthermore, since the cross-sectional shape of the heat transfer tube 30d is generally triangular, the heat transfer tube 30d has a longer wetting edge length (of the heat transfer surface in the cross section) compared to a circular tube having the same flow path cross-sectional area as the heat transfer tube 30d. Full length). Therefore, even if the heat transfer coefficient on the inner peripheral surface is equal between the heat transfer tube 30d and the circular tube, the value of (overall heat transfer coefficient × heat transfer area) can be increased. Thereby, further improvement in heat transfer performance can be expected.

  Next, the condenser 63 shown in FIG. 20 is obtained by further modifying the condenser 53 described with reference to FIG. Specifically, in the condenser 53 described with reference to FIG. 19, the condenser 63 is obtained by moving the second heat transfer tube 30B in the horizontal direction. That is, in the condenser 63 of this modification, the position G of the center of gravity of the first heat transfer tube 30A is offset in the horizontal direction from the position G of the center of gravity of the second heat transfer tube 30B. The reference line β1 that passes through the first corner portion 31 of the first heat transfer tube 30A and is parallel to the vertical direction passes through the second corner portion 32 of the second heat transfer tube 30B and is parallel to the vertical direction. It is separated from the line β2 by a predetermined distance L in the horizontal direction.

  In other words, the condenser 63 has the following configuration. In the longitudinal section of the condenser 63, a plurality of heat transfer tubes 30d are arranged in a lattice pattern. The positions of the first corner portions 31 of the plurality of heat transfer tubes 30d located at odd-numbered stages in the vertical direction are aligned with each other in the horizontal direction. The second corner portion 32 of the heat transfer tube 30d located at the even-numbered stage in the vertical direction is located between the first corner portion 31 and the apex 33p of the heat transfer tube 30d located at the odd-numbered stage in the horizontal direction. .

  According to such a configuration, the liquid-phase refrigerant is detached from the first corner portion 31 of the first heat transfer tube 30A, and is below the second heat transfer tube 30B without contacting the second heat transfer tube 30B. It reaches the first heat transfer surface 34 of the heat tube 30d (having the same arrangement as the first heat transfer tube 30A). That is, according to the condenser 63 shown in FIG. 20, compared to the condenser 53 shown in FIG. 19, the influence of the liquid-phase refrigerant flowing down from the upper heat transfer tube 30 d to the lower heat transfer tube 30 d is more affected. It can be reliably excluded. Therefore, further improvement in heat transfer coefficient can be expected.

  However, the predetermined distance L is not particularly limited. For example, the second heat transfer tube 30B may be located between the first heat transfer tube 30A and the first heat transfer tube 30A that are adjacent to each other in the horizontal direction. That is, as described with reference to FIG. 7, the first heat transfer tubes 30 </ b> A and the second heat transfer tubes 30 </ b> B may be arranged in an alternating pattern. The predetermined distance L may substantially coincide with the predicted diameter φ of the droplet W.

  The heat exchanger disclosed in the present specification can be used for various devices such as an air conditioner, a chiller, and a heat storage device.

DESCRIPTION OF SYMBOLS 10 Refrigeration cycle apparatus 11 Evaporator 12 Compressor 13, 23, 43, 53, 63 Condenser 14 Flow control valve 20 Shell 30, 30c, 30d Heat transfer tube 30A 1st heat transfer tube 30B 2nd heat transfer tube 31 1st corner | angular part 32 Second corner 33 Top 33p Vertex 34 First heat transfer surface 35 Second heat transfer surface 36 Third heat transfer surface (bottom surface)
V1 First reference line V2 Second reference line Vr Vertical reference line Hr Horizontal reference line G Center of gravity

Claims (12)

Shell,
A plurality of heat transfer tubes disposed inside the shell;
With
The plurality of heat transfer tubes are arranged in parallel to each other,
Each of the plurality of heat transfer tubes has a curvature radius profile that is smaller than a radius of a circle having the same area as the cross-sectional area of each of the plurality of heat transfer tubes in a vertical cross section perpendicular to the longitudinal direction of each of the plurality of heat transfer tubes. Having a first corner that is a portion indicating
The first corner portion constitutes a lowermost portion of each of the plurality of heat transfer tubes in the vertical direction,
Each of the plurality of heat transfer tubes includes an apex located at the top in the vertical direction,
When the upper heat transfer tube selected from the pair of heat transfer tubes adjacent to each other in the vertical direction is defined as a first heat transfer tube, and the lower heat transfer tube is defined as a second heat transfer tube, the first heat transfer tube is defined. The first corner of the heat pipe is in a position horizontally away from the apex of the second heat transfer pipe,
Each of the plurality of heat transfer tubes has three or more than three portions showing a contour of a radius of curvature smaller than a radius of a circle having the same area as the cross-sectional area of each of the plurality of heat transfer tubes in the longitudinal section. A heat exchanger. The first corner is a portion located at one end of each of the plurality of heat transfer tubes in the horizontal direction,
Each of the plurality of heat transfer tubes further includes a second corner that is a portion located at the other end in the horizontal direction,
In the longitudinal section, the first corner of the first heat transfer tube and the first corner of the second heat transfer tube are present on a first reference line parallel to the vertical direction, 2. The heat according to claim 1, wherein the second corner of the first heat transfer tube and the second corner of the second heat transfer tube exist on a second reference line parallel to the vertical direction. Exchanger.   The heat exchanger according to claim 1 or 2, wherein the plurality of heat transfer tubes are arranged in a lattice shape in the longitudinal section.   The heat exchanger according to claim 1 or 2, wherein the plurality of heat transfer tubes are arranged in a staggered pattern in the longitudinal section.   The heat exchanger according to any one of claims 1 to 4, wherein a regular polygon having a minimum area surrounding each of the plurality of heat transfer tubes is an equilateral triangle in the longitudinal section.   6. The heat exchanger according to claim 5, wherein the bottom surfaces of the plurality of heat transfer tubes are flat surfaces and are inclined in a range of 10 to 20 degrees with respect to the horizontal direction.   Each of the contours of the plurality of heat transfer tubes in the longitudinal section has a concave portion that is drawn toward the inside of each of the plurality of heat transfer tubes from the equilateral triangle having the smallest area surrounding the heat transfer tubes. The heat exchanger according to claim 5.   8. Any one of claims 1 to 7, wherein, in the longitudinal section, the contours of the plurality of heat transfer tubes are asymmetric with respect to a reference line that passes through the center of gravity of the plurality of heat transfer tubes and is parallel to the vertical direction. The heat exchanger according to claim 1. The first corner is a portion located at one end of each of the plurality of heat transfer tubes in the horizontal direction,
Each of the plurality of heat transfer tubes further includes a second corner that is a portion located at the other end in the horizontal direction,
The heat exchanger according to any one of claims 1 to 8, wherein the second corner is positioned above the first corner in the vertical direction. The inclination angle of the bottom surface of the first heat transfer tube with respect to the horizontal direction is equal to the inclination angle of the bottom surface of the second heat transfer tube with respect to the horizontal direction,
The heat exchanger according to claim 5 or 6, wherein an inclination direction of the bottom surface of the first heat transfer tube with respect to the horizontal direction is different from an inclination direction of the bottom surface of the second heat transfer tube with respect to the horizontal direction. In the longitudinal section, the plurality of heat transfer tubes are arranged in a lattice pattern,
In the longitudinal section, the regular polygon of the minimum area surrounding each of the plurality of heat transfer tubes is a regular triangle,
Each bottom surface of the plurality of heat transfer tubes is a flat surface,
The inclination angle of the bottom surface of the first heat transfer tube with respect to the horizontal direction is equal to the inclination angle of the bottom surface of the second heat transfer tube with respect to the horizontal direction,
The inclination direction of the bottom surface of the first heat transfer tube with respect to the horizontal direction is different from the inclination direction of the bottom surface of the second heat transfer tube with respect to the horizontal direction,
The positions of the first corners of the plurality of heat transfer tubes located in odd stages in the vertical direction are aligned with each other in the horizontal direction;
The second corner portion of the heat transfer tube located at the even-numbered stage in the vertical direction is located between the first corner portion of the heat-transfer tube located at the odd-numbered stage and the apex with respect to the horizontal direction. The heat exchanger according to claim 1. An evaporator for heating the refrigerant;
A compressor for compressing the refrigerant;
The condenser for condensing the refrigerant;
With
The refrigeration cycle apparatus in which the condenser is configured by the heat exchanger according to any one of claims 1 to 11.

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