Evaporator

Abstract

To improve performance by improving heat exchange efficiency in a heat transfer pipe group.SOLUTION: An evaporator comprises: a heat transfer pipe group comprising a plurality of heat transfer pipes inside which a heat exchange medium flows; a connection part 51 for introducing a refrigerant expanded by an expansion part, and in a gas-liquid two-phase state where a liquid refrigerant and air bubbles are mixed; a mixing part 53 to which the refrigerant introduced by the connection part 51 is supplied, and for mixing the supplied refrigerant; and a header 54 for supplying the refrigerant mixed by the mixing part 53, to the heat transfer pipe group.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an evaporator. [Background technology]

[0002] A liquid film type evaporator is known as an evaporator used in a refrigerator, in which a liquid refrigerant is supplied from above to a group of heat transfer tubes through which a cooled medium flows. The refrigerant is expanded by an expansion valve and introduced into the liquid film type evaporator through a pipe (for example, Patent Document 1). Patent Document 1 discloses an evaporator in which refrigerant received from a condenser is supplied to a tube bundle from a plurality of positions via a distributor. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2006 / 0080998 Summary of the Invention [Problem to be solved by the invention]

[0004] The refrigerant flowing toward the evaporator may experience gas entrainment or flashing due to a drop in pressure. For this reason, the refrigerant flowing toward the evaporator is in a gas-liquid two-phase state, with air bubbles contained in the liquid refrigerant (hereinafter referred to as "liquid refrigerant"). Furthermore, when the refrigerant in a gas-liquid two-phase state flows toward the evaporator, it passes through curved sections of the pipe or sections with uneven cross sections of the flow path, which can cause uneven distribution of bubbles in the refrigerant liquid at the cross section of the flow path. Specifically, for example, at curved sections of the pipe, the difference in specific gravity between the bubbles and the refrigerant liquid can cause the refrigerant liquid to tend to move toward the outer periphery, while the bubbles tend to tend to move toward the inner periphery. This can reduce the uniformity of the refrigerant liquid and the bubbles at the cross section of the flow path. The refrigerant introduced into the evaporator is supplied to the heat transfer tube bundle, but if the refrigerant is supplied to the heat transfer tube bundle in a gas-liquid two-phase state with reduced uniformity, the amount of refrigerant supplied will vary depending on the position, which can reduce the heat exchange efficiency in the heat transfer tube bundle and reduce the performance of the evaporator.

[0005] The present disclosure has been made in consideration of the above circumstances, and has an object to provide an evaporator that can improve the heat exchange efficiency in a heat transfer tube group and thereby improve performance. [Means for solving the problem]

[0006] In order to solve the above problems, the evaporator of the present disclosure employs the following measures. An evaporator according to one aspect of the present disclosure includes a heat transfer tube group having a plurality of heat transfer tubes through which a heat exchange medium flows, an inlet section that introduces a refrigerant in a gas-liquid two-phase state, a mixing section that receives and mixes the refrigerant introduced by the inlet section, and a supply section that supplies the refrigerant mixed in the mixing section to the heat transfer tube group. [Effects of the Invention]

[0007] According to the present disclosure, the heat exchange efficiency in the heat transfer tube group can be improved, and the performance of the evaporator can be improved. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a perspective view showing an evaporator according to a first embodiment of the present disclosure. [Figure 2] 1 is a perspective view showing an evaporator according to a first embodiment of the present disclosure, with a shell and a cover removed. [Figure 3] 1 is a schematic vertical cross-sectional view showing a main part of an evaporator according to a first embodiment of the present disclosure. [Figure 4] FIG. 2 is a perspective view showing a mixing section provided in the evaporator according to the first embodiment of the present disclosure. [Figure 5] FIG. 4 is a schematic vertical cross-sectional view showing a main part of an evaporator according to a modified example of the first embodiment of the present disclosure. [Figure 6] FIG. 10 is a perspective view showing a mixing portion provided in an evaporator according to a modified example of the first embodiment of the present disclosure. [Figure 7] FIG. 5 is a schematic vertical cross-sectional view showing a main part of an evaporator according to a second embodiment of the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] An embodiment of an evaporator according to the present disclosure will be described below with reference to Figures 1 to 7. In the following description and drawings, the vertical direction is defined as the Z-axis direction, the direction in which the heat transfer tubes extend is defined as the X-axis direction, and the direction perpendicular to the Z-axis direction and the X-axis direction is defined as the Y-axis direction.

[0010] [First embodiment] The evaporator 1 according to this embodiment is applied to a turbo refrigeration system. The turbo refrigeration system is configured as a unit, including a turbo compressor (not shown) that compresses a refrigerant, a condenser (not shown) that condenses the refrigerant compressed by the turbo compressor, an expansion valve (not shown) that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant expanded by the expansion valve. Each device is connected by piping through which the refrigerant flows. For example, a low-pressure refrigerant such as R1233zd, which is used at a maximum pressure of less than 0.2 MPaG, is used as the refrigerant. However, applicable refrigerants are not limited to low-pressure refrigerants. For example, a high-pressure refrigerant may also be used as the refrigerant.

[0011] The evaporator 1 is supplied with a two-phase gas-liquid refrigerant expanded by an expansion valve. As shown in Figures 1 and 2, the evaporator 1 includes a pressure vessel 10 forming an outer shell, a refrigerant inlet pipe (inlet portion) 20 that introduces the two-phase gas-liquid refrigerant expanded by the expansion valve into the pressure vessel 10, a heat transfer tube group 30 housed inside the pressure vessel 10, a cover 40 that covers the heat transfer tube group 30 from above, and a supply device 50 that is provided above the heat transfer tube group 30 and supplies the refrigerant introduced through the refrigerant inlet pipe 20 to the heat transfer tube group 30. Note that, for convenience of illustration, the pressure vessel 10 and the cover 40 are omitted in Figure 2. For convenience of illustration, the pressure vessel 10 is shown transparently in Figure 1.

[0012] As shown in FIG. 1 , the pressure vessel 10 integrally comprises a cylindrical portion 11 whose central axis extends along the X-axis direction, and two tube plates (not shown) that close both ends of the cylindrical portion 11 in the direction along the central axis (X-axis direction). The cylindrical portion 11 is arranged so that its central axis is approximately horizontal. Each tube plate is a disk-shaped plate. A liquid refrigerant is stored in the lower part of the pressure vessel 10. An outlet opening 12 is provided at the upper end of the cylindrical portion 11, connecting the internal space of the pressure vessel 10 with the external space. The outlet opening 12 is provided at one end in the X-axis direction. An inlet opening 13 is provided at the side of the cylindrical portion 11, connecting the internal space of the pressure vessel 10 with the external space. A refrigerant inlet pipe 20 is inserted into the inlet opening 13. In the following description, when the terms "inside" and "outside" are simply used, they refer to the "inside" and "outside" relative to the central axis of the cylindrical portion 11. In other words, the "inside" refers to the side of the central axis of the cylindrical portion 11, and the "outside" refers to the side of the inner peripheral surface of the cylindrical portion 11.

[0013] A gas-liquid two-phase refrigerant flows through the refrigerant inlet pipe 20. The refrigerant inlet pipe 20 includes a first horizontal pipe 21 extending in the Y-axis direction, a second horizontal pipe 22 bending at a substantially right angle from the downstream end of the first horizontal pipe 21 and extending in the X-axis direction, a vertical pipe 23 bending at a substantially right angle from the downstream end of the second horizontal pipe 22 and extending upward, and a third horizontal pipe 24 bending at a substantially right angle from the downstream end (upper end) of the vertical pipe 23 and extending in the X-axis direction.

[0014] The first horizontal pipe 21, the second horizontal pipe 22, and the vertical pipe 23 are provided outside the pressure vessel 10. The third horizontal pipe 24 passes through the inlet opening 13. That is, a portion of the third horizontal pipe 24 is provided outside the pressure vessel 10, and a portion of the third horizontal pipe 24 is provided inside the pressure vessel 10.

[0015] The refrigerant inlet pipe 20 is provided with a fourth horizontal pipe 25 arranged above the heat transfer pipe group 30 and extending linearly in the X-axis direction, fifth horizontal pipes 26 arranged at both ends of the fourth horizontal pipe 25 in the X-axis direction and extending linearly in the Y-axis direction, and supply pipes 27 curved downward at approximately right angles from both ends of the pair of fifth horizontal pipes 26 in the Y-axis direction.

[0016] The fourth horizontal pipe 25, the fifth horizontal pipe 26, and the supply pipe 27 are housed inside the pressure vessel 10. The fourth horizontal pipe 25, the fifth horizontal pipe 26, and the supply pipe 27 are provided at the upper part of the pressure vessel 10. The fourth horizontal pipe 25, the fifth horizontal pipe 26, and the supply pipe 27 are provided above the cover 40.

[0017] The fourth horizontal pipe 25 is provided in approximately the center in the X-axis direction inside the pressure vessel 10. The downstream end of the third horizontal pipe 24 is connected to the side surface of the fourth horizontal pipe 25 at approximately the center in the X-axis direction. The downstream end (one end or the other end in the X-axis direction) of the third horizontal pipe 24 is connected to the side surface of each fifth horizontal pipe 26 at approximately the center in the Y-axis direction. The downstream end (lower end) of the supply pipe 27 is connected to the supply device 50. The supply pipe 27 passes through the cover 40.

[0018] In this way, the refrigerant inlet pipe 20 has a plurality of curved portions (for example, the connection portion between the first horizontal pipe 21 and the second horizontal pipe 22, the connection portion between the fifth horizontal pipe 26 and the supply pipe 27, etc.).

[0019] 1 and 2, the heat transfer tube group 30 includes a flooded heat transfer tube group 31, a lower liquid film type heat transfer tube group 32, and an upper liquid film type heat transfer tube group 33. For convenience of illustration, each heat transfer tube included in each heat transfer tube group is not shown in FIGS.

[0020] The liquid-flooded heat transfer tube group 31 is housed in the pressure vessel 10. The liquid-flooded heat transfer tube group 31 is immersed in the liquid refrigerant stored in the lower part of the pressure vessel 10. In other words, the liquid-flooded heat transfer tube group 31 is disposed below the liquid level of the stored refrigerant.

[0021] The lower liquid film type heat transfer tube group 32 is housed in the pressure vessel 10. The lower liquid film type heat transfer tube group 32 is provided above the liquid-filled type heat transfer tube group 31. The lower liquid film type heat transfer tube group 32 is disposed above the liquid level of the stored refrigerant. The upper liquid film type heat transfer tube group 33 is housed in the pressure vessel 10. The upper liquid film type heat transfer tube group 33 is provided above the lower liquid film type heat transfer tube group 32. The upper liquid film type heat transfer tube group 33 is disposed above the liquid level of the stored refrigerant. The lower liquid film type heat transfer tube group 32 and the upper liquid film type heat transfer tube group 33 are spaced apart in the vertical direction.

[0022] The flooded heat transfer tube group 31, the lower liquid film type heat transfer tube group 32, and the upper liquid film type heat transfer tube group 33 each have a plurality of heat transfer tubes extending along the X-axis direction. The plurality of heat transfer tubes are arranged substantially parallel to one another. The plurality of heat transfer tubes are arranged in parallel at predetermined intervals in the vertical and Y-axis directions. Specifically, the plurality of heat transfer tubes are arranged in multiple rows in the vertical direction and multiple columns in the Y-axis direction. Water (hereinafter referred to as "cooled water") serving as a heat exchange medium flows through each heat transfer tube. Each heat transfer tube is formed linearly. Each heat transfer tube extends from one end to the other end of the pressure vessel 10 in the X-axis direction and penetrates each tube plate (not shown). The length in the X-axis direction of the flooded heat transfer tube group 31, the lower liquid film type heat transfer tube group 32, and the upper liquid film type heat transfer tube group 33 is longer than the length in the X-axis direction of a header (supply section) 54 (see FIG. 2), which will be described later.

[0023] The cover 40 is arranged so that its plate surface is horizontal. The cover 40 is arranged above the header 54 of the supply device 50. A plurality of supply pipes 27 pass through the cover 40. The cover 40 extends along the upper liquid film heat transfer tube group 33 over substantially the entire area of ​​the pressure vessel 10 in the X-axis direction. The cover 40 may be provided over only a portion of the X-axis direction.

[0024] 2 and 3, the supply device 50 is provided at the lower end of each supply pipe 27. Since the structure of each supply device 50 is substantially the same, the following description will be given of one supply device 50 as a representative, and a description of the other supply devices 50 will be omitted.

[0025] The supply device 50 includes a connection section (introduction section) 51 connected to the lower end of the supply pipe 27, a rectangular section 52 connected to the lower end of the connection section 51 and having a rectangular shape in a planar view, a mixing section 53 provided below the rectangular section 52, and a pair of headers 54 connected to both ends of the rectangular section 52 in the Y-axis direction.

[0026] As shown in Fig. 3, the connection part 51 is a cylindrical member that extends linearly in the vertical direction. The upper end of the connection part 51 is connected to the lower end of the supply pipe 27. The lower end of the connection part 51 is connected to the center of the upper surface of the rectangular part 52 in the X-axis direction and the Y-axis direction. A circular discharge port 51a that opens into the space formed inside the rectangular part 52 is formed at the lower end of the connection part 51. The diameter D2 of the discharge port 51a is shorter than the diameter D1 of the inlet 53a of the mixer 53. Furthermore, the opening area of ​​the discharge port 51a is smaller than the opening area of ​​the inlet 53a of the mixer 53.

[0027] The rectangular portion 52 is a member having a substantially square shape in a plan view. The rectangular portion 52 is a member having a substantially rectangular parallelepiped shape. A space is formed inside the rectangular portion 52. The lower end of the connection portion 51 is connected to the upper surface of the rectangular portion 52. In addition, the upper end of the mixer portion 53 is connected to the lower surface of the rectangular portion 52. At both ends in the Y-axis direction of rectangular portion 52, flow path portions 52a are provided that guide the refrigerant mixed in mixing portion 53 to header 54. Flow path portion 52a extends in the Y-axis direction from the Y-axis direction ends of outlet 51a of connection portion 51 and inlet 53a of mixing portion 53. Header 54 is connected to the Y-axis direction end of flow path portion 52a. A small-diameter portion 52b having a flow path area smaller than that of flow path portion 52a is provided at the connection portion between flow path portion 52a and header 54.

[0028] The shape of the rectangular portion 52 is not limited to the above-mentioned shape, and may be, for example, a circular shape in a plan view or an irregular shape in a plan view.

[0029] As shown in Fig. 4, the mixing section 53 is a hemispherical member and is arranged so as to be convex downward. A space is formed inside the mixing section 53. The mixing section 53 is formed so that its horizontal cross section becomes smaller toward the bottom. The bottom surface 53b of the mixing section 53 is a curved surface.

[0030] The upper end of the mixing section 53 is connected to the center in the X-axis direction and the Y-axis direction of the lower surface of the rectangular section 52. A circular inlet 53a that opens into the space formed inside the rectangular section 52 is formed at the upper end of the mixing section 53. The diameter D1 of the inlet 53a is longer than the diameter D2 of the outlet 51a of the connecting section 51. The opening area of ​​the inlet 53a is also larger than the opening area of ​​the outlet 51a of the connecting section 51. The connecting portion between the mixing section 53 and the rectangular section 52 is at the same height position throughout the circumferential direction. That is, the inlet 53a is formed so as to be along a horizontal plane. By forming the inlet 53a in this manner, mixing can be performed more efficiently.

[0031] The discharge outlet 51a of the connection part 51 and the inlet 53a of the mixing part 53 are arranged so that the entire area of ​​the discharge outlet 51a overlaps with the inlet 53a in a plan view. In addition, the discharge outlet 51a of the connection part 51 and the inlet 53a of the mixing part 53 are spaced apart in the vertical direction due to the presence of the rectangular part 52.

[0032] As shown in FIG. 2, the header 54 is a tubular member extending along the X-axis direction. The header 54 is formed in a substantially rectangular shape in a side view. Furthermore, as shown in FIG. 3, the header 54 is curved so that its lower end protrudes downward in a side view. A plurality of ejection portions (not shown) are formed at the lower end of the header 54. Each ejection portion may be formed in a slit shape with its longitudinal direction in the Y-axis direction. The plurality of ejection portions are arranged at equal intervals in the X-axis direction. The refrigerant circulating inside the header 54 is ejected from each ejection portion. The header 54 supplies the refrigerant ejected from each ejection portion to the heat transfer tube group 30 from above.

[0033] Next, the flow of refrigerant in the evaporator 1 according to this embodiment will be described. The refrigerant (gas-liquid two-phase flow) expanded by the expansion valve flows through the refrigerant inlet pipe 20 and is introduced into the pressure vessel 10. The refrigerant that has flowed into the pressure vessel 10 flows through the refrigerant inlet pipe 20 and is introduced into the supply device 50. The refrigerant flowing through the refrigerant inlet pipe 20 is in a gas-liquid two-phase state, in which gas bubbles are contained in the liquid refrigerant (hereinafter referred to as "refrigerant liquid").

[0034] The gas-liquid two-phase flow flowing through the refrigerant inlet pipe 20 passes through curved sections and sections with uneven cross sections, causing uneven distribution of bubbles in the refrigerant liquid at the cross section of the flow path. Specifically, for example, at curved sections, the refrigerant liquid moves toward the outer periphery, while the bubbles move toward the inner periphery. In this way, the refrigerant is introduced into the supply device 50 with reduced uniformity of the refrigerant liquid and the bubbles at the cross section of the flow path.

[0035] As shown in Fig. 3, the refrigerant introduced into supply device 50 is introduced into mixing section 53 via connection section 51 and rectangular section 52. At this time, the refrigerant flows from above downward (see arrow A1), and mixing section 53 receives the refrigerant at bottom surface 53b. The refrigerant in the gas-liquid two-phase flow introduced into mixing section 53 is mixed into refrigerant liquid and gas bubbles in mixing section 53. The mixed refrigerant overflows mixing section 53 and flows into flow path section 52a (see arrow A2). The refrigerant that has flowed into flow path section 52a flows within flow path section 52a and is introduced into header 54 via small diameter section 52b.

[0036] As shown in FIG. 2, the liquid-phase refrigerant flowing through the header 54 is sprayed downward through multiple spray ports (not shown) formed at the bottom of the header 54. The liquid-phase refrigerant sprayed from the header 54 comes into contact with the heat transfer tubes located at the top of the liquid film type heat transfer tube groups (the upper liquid film type heat transfer tube group 33 and the lower liquid film type heat transfer tube group 32) and coats the outer circumferential surfaces of the heat transfer tubes in a film-like manner. The refrigerant coating the outer circumferential surfaces of the heat transfer tubes in a film-like manner exchanges heat with the cooled water inside the heat transfer tubes. Some of the refrigerant evaporates through the heat exchange, and the remaining refrigerant falls to the heat transfer tubes located further below. This heat exchange is continuously repeated. The refrigerant that does not evaporate even after heat exchange with the water inside the lowest heat transfer tube is accumulated in the lower part of the pressure vessel 10. In this way, a pool of liquid-phase refrigerant is formed inside the pressure vessel 10. The liquid level of this refrigerant pool is automatically adjusted to a predetermined height. The heat transfer tubes of the flooded heat transfer tube group 31 are immersed in the stored liquid phase refrigerant. The cooled water flowing through the heat transfer tubes exchanges heat with the stored refrigerant. The refrigerant that has exchanged heat with the heat transfer tubes evaporates and is guided upward from the liquid surface. The refrigerant that has evaporated in the upper liquid film type heat transfer tube group 33, the lower liquid film type heat transfer tube group 32, and the flooded type heat transfer tube group 31 is guided to the outlet opening 12 (see Figure 1). The refrigerant guided to the outlet opening 12 is discharged to the outside of the pressure vessel 10. The refrigerant discharged to the outside of the pressure vessel 10 is sucked into and compressed by the turbo compressor.

[0037] According to this embodiment, the following advantageous effects are achieved. In this embodiment, a mixer 53 is provided that mixes refrigerant in a gas-liquid two-phase state, and the refrigerant mixed in the mixer 53 is supplied to the heat transfer tube group 30. As a result, the refrigerant in a state in which the gas phase refrigerant and the liquid phase refrigerant are mixed in the mixer 53 is supplied to the heat transfer tube group 30. This makes it possible to uniformize the amount of refrigerant supplied to the heat transfer tube group 30. This improves the heat exchange efficiency in the heat transfer tube group 30, and improves the performance of the evaporator 1.

[0038] In the present embodiment, mixing unit 53 is provided below connecting unit 51 and receives the refrigerant discharged from connecting unit 51. As a result, when the refrigerant is received by mixing unit 53, the gas phase refrigerant and the liquid phase refrigerant are mixed by the impact. Therefore, in mixing unit 53, the gas phase refrigerant and the liquid phase refrigerant can be mixed more suitably.

[0039] In the present embodiment, the opening area of ​​inlet 53a of mixer 53 is larger than the opening area of ​​outlet 51a of connection part 51. This allows refrigerant to be suitably introduced into mixer 53. Therefore, in mixer 53, gas-phase refrigerant and liquid-phase refrigerant can be more suitably mixed.

[0040] The present disclosure is not limited to the above-described embodiments, and various modifications can be made without departing from the spirit of the present disclosure.

[0041] For example, in the above embodiment, an example was described in which the mixer 53 is a hemispherical member, but the present disclosure is not limited to this. For example, the mixer may be cylindrical, as shown in Figures 5 and 6. In the cylindrical mixer 53A, the opening area of ​​the introduction opening 53Aa and the area of ​​the bottom surface 53Ab are approximately the same. The shape of the mixing section may be a cone, a truncated cone, a polygonal pyramid, a polygonal pyramid, or a combination of these. However, the mixing section can mix the refrigerants preferably if it has a shape whose cross-sectional shape does not change over the entire vertical direction or a shape whose cross-sectional area decreases downward.

[0042] Furthermore, for example, in the above embodiment, an example has been described in which the present disclosure is applied to an evaporator in which the refrigerant mixed in the mixing section is supplied to the header 54 and sprayed from the header 54 toward a group of heat transfer tubes, but the evaporators to which the present disclosure can be applied are not limited to the evaporator described above. 7, the present disclosure may be applied to an evaporator 1 in which a tray 60 is provided instead of the header 54. A supply device 50B provided in this evaporator 1 supplies the refrigerant mixed in the mixing section 53A to a tray 60 provided below and spaced apart from the mixing section 53A (see arrow A3), and drips the refrigerant from a plurality of holes formed in the bottom surface of the tray 60 toward the heat transfer tube group 30 (see arrow A4). In this way, the present disclosure is applicable to both tray-type evaporators and spray-type evaporators.

[0043] The evaporator according to the above-described embodiment can be understood, for example, as follows. The evaporator according to the first aspect of the present disclosure includes a heat transfer tube group (30) having a plurality of heat transfer tubes through which a heat exchange medium flows, an inlet section (20, 51) that introduces a refrigerant in a gas-liquid two-phase state, a mixing section (53) that receives the refrigerant introduced in the inlet section and mixes the supplied refrigerant, and a supply section (54) that supplies the refrigerant mixed in the mixing section to the heat transfer tube group.

[0044] The above-described configuration includes a mixing section that mixes gas-liquid two-phase refrigerant, and supplies the refrigerant mixed in the mixing section to the heat transfer tube group. This allows the refrigerant mixed in the mixing section and the gas-phase refrigerant mixed in the liquid-phase refrigerant to be supplied to the heat transfer tube group. This makes it possible to uniformize the amount of refrigerant supplied to the heat transfer tube group. This improves the heat exchange efficiency in the heat transfer tube group and improves the performance of the evaporator.

[0045] In the evaporator according to a second aspect of the present disclosure, in the above-mentioned first aspect, the mixing section is provided below the introduction section and receives the refrigerant discharged from the introduction section.

[0046] In the above configuration, the mixing section is provided below the introduction section and receives the refrigerant discharged from the introduction section. As a result, when the refrigerant is received in the mixing section, the impact causes the gas phase refrigerant and the liquid phase refrigerant to mix. Therefore, the gas phase refrigerant and the liquid phase refrigerant can be more suitably mixed in the mixing section.

[0047] An evaporator according to a third aspect of the present disclosure is the evaporator of the first or second aspect, wherein the introduction section has an outlet (51 a) for discharging the refrigerant, the mixing section has an inlet (53 a) for introducing the refrigerant discharged from the introduction section, and the opening area of ​​the inlet is larger than the opening area of ​​the outlet.

[0048] In the above configuration, the opening area of ​​the inlet of the mixing section is larger than the opening area of ​​the outlet of the inlet section, which allows the refrigerant to be introduced into the mixing section more efficiently, thereby allowing the gas phase refrigerant and the liquid phase refrigerant to be mixed more efficiently in the mixing section. [Explanation of symbols]

[0049] 1: Evaporator 10: Pressure vessel 11: Cylindrical part 12 :Exit opening 13 :Inlet opening 20: Refrigerant inlet pipe (introduction part) 21: 1st horizontal pipe 22:Second horizontal pipe 23: Vertical pipe 24:Third horizontal pipe 25: 4th horizontal pipe 26: 5th horizontal pipe 27: Supply pipe 30: Heat transfer tube group 31: Flooded heat transfer tube bank 32: Lower liquid film type heat transfer tube group 33: Upper liquid film type heat transfer tube group 40: Cover 50: Feeding device 50B: Feeding device 51: Connection section (introduction section) 51a: Outlet 52: Rectangular part 52a: flow path section 52b: Small diameter section 53: Mixing section 53A: Mixing section 53Aa: Introduction opening 53Ab: Bottom 53a: Entrance 53b: Bottom 54: Header (supply section) 60: Tray

Claims

1. a heat transfer tube group including a plurality of heat transfer tubes through which a heat exchange medium flows; an introduction section for introducing a refrigerant in a gas-liquid two-phase state; a mixing section that receives the refrigerant introduced by the introduction section and mixes the supplied refrigerant; a supply section that supplies the refrigerant mixed in the mixing section to the heat transfer tube group.

2. The evaporator according to claim 1 , wherein the mixing section is provided below the inlet section and receives the refrigerant discharged from the inlet section.

3. the introduction section has an outlet for discharging the refrigerant, the mixing section has an inlet for introducing the refrigerant discharged from the inlet section, 3. The evaporator according to claim 1, wherein an opening area of ​​the inlet is larger than an opening area of ​​the outlet.

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