Evaporator

Abstract

The evaporator (10) comprises: a pressure vessel (11) having a refrigerant outlet pipe (16) for discharging evaporated refrigerant; a flooded heat transfer tube group (14) immersed in liquid-phase refrigerant stored in a storage portion (11c) provided at the lower portion of the pressure vessel (11), and having a plurality of first heat transfer tubes (14a) through which cooling water circulates; a liquid film heat transfer tube group (15) provided at a position higher than a liquid level (S) of the liquid-phase refrigerant stored at the lower portion of the pressure vessel (11), and having a plurality of second heat transfer tubes (15a) through which cooling water circulates; a refrigerant tray (13) for supplying liquid-phase refrigerant to the liquid film heat transfer tube group (15) from above; and a gas-liquid separation flow path (20) for guiding the refrigerant evaporated in the liquid film heat transfer tube group (15) to the refrigerant outlet pipe (16). The gas-liquid separation flow path (20) comprises: an ascending flow path (23) for allowing the refrigerant to flow from the bottom to the top; a descending flow path (24) for allowing the refrigerant to flow from the top to the bottom; and a connecting flow path (25) for connecting the ascending flow path (23) and the descending flow path (24) and for folding the refrigerant back.

Description

Technical Field

[0001] The present invention relates to an evaporator. Background Art

[0002] As an evaporator used in a refrigerator, a liquid film type evaporator is known (for example, Patent Document 1), in which a liquid-phase refrigerant is supplied from above to a heat transfer tube group through which a medium to be cooled flows.

[0003] Patent Document 1 describes an evaporator in which refrigerant evaporated in a heat transfer tube group is guided to a suction pipe provided in a shell via a suction slit formed in a baffle wall.

[0004] Previous technical literature

[0005] Patent Literature

[0006] Patent Document 1: U.S. Patent No. 8,944,152 Summary of the Invention

[0007] Technical issues to be solved by the invention

[0008] In liquid film evaporators, the heat transfer tube assembly is positioned above the pressure vessel, leading to a tendency for the heat transfer tube assembly and the refrigerant outlet to be close together. Consequently, the gaseous refrigerant discharged outside the housing is easily carried along with the liquid refrigerant (so-called carryover). Furthermore, the placement of the heat transfer tube assembly above the pressure vessel narrows the space above the heat transfer tube assembly. Consequently, for example, it is difficult to install a gas-liquid separation mechanism in the space above the heat transfer tube assembly.

[0009] Furthermore, in Patent Document 1, because the refrigerant guided to the suction pipe is bent back horizontally, sufficient gas-liquid separation of the refrigerant cannot be achieved. This can lead to the gaseous refrigerant discharged outside the housing being accompanied by liquid refrigerant (so-called entrainment). If entrainment occurs, the liquid refrigerant can be drawn into the turbo compressor located downstream of the evaporator. If the liquid refrigerant is drawn into the turbo compressor, the compression ratio of the turbo compressor decreases, reducing efficiency, and potentially damaging the turbo compressor blades, etc.

[0010] Furthermore, to separate the refrigerant from gas and liquid, a demister or similar device could be installed between the refrigerant outlet on the exterior of the guide frame and the heat transfer tube assembly. However, demisters are relatively expensive components. Furthermore, to ensure the demister's separation performance, the flow velocity in front of the demister must be suppressed, which increases the size of the evaporator. Therefore, installing a demister may increase the initial cost of the evaporator.

[0011] The present invention has been made in view of such circumstances, and an object of the present invention is to provide an evaporator that can make entrainment less likely to occur.

[0012] Another object is to provide an evaporator capable of reducing initial costs.

[0013] Means for solving technical problems

[0014] In order to solve the above-mentioned problems, the evaporator of the present invention adopts the following solutions.

[0015] An evaporator according to one embodiment of the present invention includes: a frame having a refrigerant outlet for discharging evaporated refrigerant and constituting an outer shell; a first heat transfer tube group accommodated in the frame and immersed in liquid-phase refrigerant stored in a storage portion provided in a lower portion of the frame, and having a plurality of first heat transfer tubes through which the cooling medium circulates; a second heat transfer tube group accommodated in the frame and provided above a liquid level of the liquid-phase refrigerant stored in the lower portion of the frame, and having a plurality of second heat transfer tubes through which the cooling medium circulates; a refrigerant supply portion accommodated in the frame and supplying liquid-phase refrigerant to the second heat transfer tube group from above; and a flow path for guiding the refrigerant evaporated in the second heat transfer tube group to the refrigerant outlet, the flow path including: a first flow path through which the refrigerant circulates from below to above; a second flow path through which the refrigerant circulates from above to below; and a connecting flow path for connecting the first flow path and the second flow path and for returning the refrigerant.

[0016] Effects of the Invention

[0017] According to the present invention, it is possible to make entrainment less likely to occur and reduce initial costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a schematic longitudinal sectional view of the evaporator according to the first embodiment of the present invention.

[0019] Figure 2 Yes Figure 1 A longitudinal sectional view of a modified example of .

[0020] Figure 3 Yes Figure 1 A longitudinal sectional view of a modified example of .

[0021] Figure 4 It is magnified Figure 3 A stereoscopic view of the main part (part IV).

[0022] Figure 5 yes Figure 4 VV-direction sectional view.

[0023] Figure 6It is a schematic longitudinal sectional view of an evaporator according to a second embodiment of the present invention.

[0024] Figure 7 Yes Figure 6 A longitudinal sectional view of a modified example of . DETAILED DESCRIPTION

[0025] Hereinafter, one embodiment of the evaporator according to the present invention will be described with reference to the drawings.

[0026] [First embodiment]

[0027] Below, use Figure 1 In the following description and drawings, the vertical vertical direction is defined as the Z-axis direction, the direction in which the heat transfer tube extends 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.

[0028] The evaporator 10 involved in this embodiment is suitable for use in a turbo refrigeration device. The turbo refrigeration device includes a turbo compressor (not shown) that compresses the refrigerant, a condenser (not shown) that condenses the refrigerant pressurized by the turbo compressor, an expansion valve (not shown) that expands the refrigerant condensed by the condenser, and an evaporator that evaporates the refrigerant decompressed by the expansion valve, and is constructed in a unit shape. Each device is connected by a pipe for circulating the refrigerant. As the refrigerant, for example, a low-pressure refrigerant such as R1233zd used at a maximum pressure of less than 0.2 MPaG is used. In addition, the applicable refrigerant is not limited to the low-pressure refrigerant. For example, a high-pressure refrigerant can also be used as the refrigerant.

[0029] like Figure 1 As shown, the evaporator 10 includes a pressure vessel (frame) 11 constituting an outer shell, a refrigerant inlet pipe 12 for introducing refrigerant into the interior of the pressure vessel 11, a refrigerant tray (refrigerant supply unit) 13 provided below the refrigerant inlet pipe 12, a flooded heat transfer tube group (first heat transfer tube group) 14 immersed in the liquid refrigerant stored in the lower part of the pressure vessel 11, and a heat transfer tube group 15 provided at a level higher than the liquid level S (reference level) of the liquid refrigerant stored in the lower part of the pressure vessel 11. Figure 2 and Figure 3 ) is provided with a liquid film heat transfer tube group (second heat transfer tube group) 15 at a position further above the pressure vessel 11, a refrigerant outlet pipe (refrigerant outlet) 16 for discharging the evaporated refrigerant from the pressure vessel 11, a baffle 17 covering the liquid film heat transfer tube group 15 from the side, and a gas-liquid separation flow path (flow path) 20 that guides the refrigerant evaporated in the flooded heat transfer tube group 14 and the liquid film heat transfer tube group 15 to the refrigerant outlet pipe 16.

[0030] The pressure vessel 11 integrally comprises a cylindrical portion 11a whose central axis extends in the X-axis direction, and two tube sheets (not shown) that close the two ends of the cylindrical portion 11a along the central axis (the X-axis direction). The cylindrical portion 11a is positioned so that its central axis is approximately horizontal. Each tube sheet is a disc-shaped plate. Liquid refrigerant is stored in the lower portion of the pressure vessel 11. Hereinafter, the area storing the liquid refrigerant is referred to as the storage portion 11c.

[0031] In the following description, the terms "inside" and "outside" are used with reference to the central axis of the cylindrical portion 11a. Specifically, "inside" refers to the central axis side of the cylindrical portion 11a, and "outside" refers to the inner circumferential surface side of the cylindrical portion 11a.

[0032] The refrigerant inlet pipe 12 is a cylindrical member extending vertically and formed in a generally straight line. It is installed vertically through the upper portion of the cylindrical portion 11a. It is located approximately at the center of the cylindrical portion 11a in the X-axis direction. The refrigerant inlet pipe 12 is connected to the piping (not shown) connecting the evaporator 10 and the expansion valve. Specifically, the refrigerant expanded by the expansion valve is guided into the pressure vessel 11 via the refrigerant inlet pipe 12.

[0033] The refrigerant tray 13 is a roughly rectangular plate-shaped component. It is positioned so that its plate surface is roughly horizontal within the upper portion of the pressure vessel 11. Furthermore, its plate surface faces the lower end of the refrigerant inlet pipe 12. Its two ends in the Y-axis direction are separated by a predetermined distance from the inner circumference of the cylindrical portion 11a of the pressure vessel 11. Furthermore, the refrigerant tray 13 extends over substantially the entire area of the pressure vessel 11 in the X-axis direction. Its two ends in the X-axis direction are fixed to the tube sheet. Multiple holes are formed vertically through the refrigerant tray 13. These holes extend over substantially the entire area of the refrigerant tray 13. Liquid refrigerant discharged from the refrigerant inlet pipe 12 is discharged into the refrigerant tray 13. The refrigerant discharged into the refrigerant tray 13 flows along its upper surface and then drops downward through the multiple holes. In this manner, the coolant tray 13 can distribute the coolant supplied from the coolant inlet pipe 12 in the X-axis direction and the Y-axis direction.

[0034] The flooded heat transfer tube group 14 is housed in the pressure vessel 11. Furthermore, the flooded heat transfer tube group 14 is immersed in the refrigerant stored in the storage portion 11c. That is, it is positioned below the liquid level S of the stored refrigerant. The flooded heat transfer tube group 14 includes a plurality of first heat transfer tubes 14a extending along the X-axis direction. The plurality of first heat transfer tubes 14a are arranged substantially in parallel. The plurality of first heat transfer tubes 14a are arranged at predetermined intervals in the vertical direction (Z-axis direction) and the Y-axis direction. Specifically, the plurality of first heat transfer tubes 14a are arranged in a plurality of segments in the vertical direction and in a plurality of segments in the Y-axis direction. Water, serving as the cooling medium (hereinafter referred to as "cooled water"), flows through each first heat transfer tube 14a. Furthermore, each first heat transfer tube 14a is formed in a straight line. Furthermore, each first heat transfer tube 14a extends from one end to the other end of the pressure vessel 11 in the X-axis direction, penetrating each tube sheet.

[0035] The liquid film heat transfer tube group 15 is housed in the pressure vessel 11. The liquid film heat transfer tube group 15 is arranged at a position higher than the liquid level S of the stored refrigerant. The liquid film heat transfer tube group 15 has a plurality of second heat transfer tubes 15a extending along the X-axis direction. The plurality of second heat transfer tubes 15a are arranged approximately in parallel. The plurality of second heat transfer tubes 15a are arranged at predetermined intervals in the vertical direction (Z-axis direction) and the Y-axis direction. Specifically, the plurality of second heat transfer tubes 15a are arranged in a plurality of sections in the vertical direction and in a plurality of sections in the Y-axis direction. Water, which is a cooling medium, circulates inside each second heat transfer tube 15a. Furthermore, each second heat transfer tube 15a is formed in a straight line. Furthermore, each second heat transfer tube 15a extends from one end to the other end of the pressure vessel 11 in the X-axis direction and penetrates each tube sheet.

[0036] The refrigerant outlet pipe 16 is a cylindrical member extending at an angle relative to the Z-axis. It is connected to an opening formed in the upper portion of the cylindrical portion 11a. It is located near the end of the cylindrical portion 11a in the X-axis direction. Specifically, it is located near the tube sheet of the pressure vessel 11. The refrigerant evaporated in the evaporator 10 is discharged to the exterior of the pressure vessel 11 via the refrigerant outlet pipe 16.

[0037] The baffle 17 is a flat plate-shaped component arranged so that the plate surface becomes a vertical plane. The baffle 17 is arranged on both sides of the liquid film heat transfer tube group 15. That is, the baffle 17 is arranged on the outer side of the liquid film heat transfer tube group 15 in the Y-axis direction. Each baffle 17 is arranged so that the plate surface is opposite to the liquid film heat transfer tube group 15. The baffle 17 extends downward from both ends of the refrigerant tray 13 in the Y-axis direction for a predetermined distance. The lower end of the baffle 17 is located above the lower end of the liquid film heat transfer tube group 15. In addition, the baffle 17 extends along the liquid film heat transfer tube group 15 over substantially the entire area in the X-axis direction of the pressure vessel 11. In addition, the baffle 17 can also be provided only in a portion in the X-axis direction.

[0038] The gas-liquid separation flow path 20 guides the refrigerant evaporated in the flooded heat transfer tube group 14 and the refrigerant evaporated in the liquid film heat transfer tube group 15 to the refrigerant outlet pipe 16. The refrigerant flowing into the pressure vessel 11 from the refrigerant inlet pipe 12 includes gaseous refrigerant. The gas-liquid separation flow path 20 also guides the gaseous refrigerant that has flowed into the space where the liquid film heat transfer tube group 15 is located via the refrigerant inlet pipe 12 and the refrigerant tray 13 to the refrigerant outlet pipe 16.

[0039] The gas-liquid separation flow paths 20 are provided on either side of the liquid film heat transfer tube group 15. The two gas-liquid separation flow paths 20 are symmetrically arranged with respect to the XZ plane passing through the central axis of the pressure vessel 11. Therefore, in the following description, one of the gas-liquid separation flow paths 20 will be described, while the description of the other gas-liquid separation flow path 20 will be omitted.

[0040] The gas-liquid separation flow path 20 includes a flat first flow path defining portion 21 disposed outside the baffle 17 in the Y-axis direction, and a plate-shaped second flow path defining portion 22 disposed outside the first flow path defining portion 21 in the Y-axis direction. The gas-liquid separation flow path 20 is provided over substantially the entire area of the pressure vessel 11 in the X-axis direction.

[0041] The first flow path defining portion 21 is positioned so as to face the baffle 17. The first flow path defining portion 21 is positioned so that its plate surface is perpendicular to the baffle 17. The first flow path defining portion 21 is spaced apart from the baffle 17. An ascending flow path 23 is formed between the first flow path defining portion 21 and the baffle 17, primarily through which the refrigerant evaporating in the liquid film heat transfer tube group 15 flows. Specifically, the ascending flow path 23 is defined by the plate surface of the first flow path defining portion 21 and the plate surface of the baffle 17.

[0042] The lower end of the first flow path defining portion 21 is located below the liquid level S of the refrigerant stored in the storage portion 11c. Furthermore, the lower end of the first flow path defining portion 21 is spaced apart from the inner circumferential surface of the pressure vessel 11. That is, a gap G is formed between the lower end of the first flow path defining portion 21 and the inner circumferential surface of the pressure vessel 11. The upper end of the first flow path defining portion 21 is located below the upper end of the baffle 17 and above the lower end of the baffle 17. Specifically, the upper end of the first flow path defining portion 21 is located at approximately the same height as the vicinity of the center of the baffle 17 in the Z-axis direction.

[0043] Furthermore, in order to prevent the circulating refrigerant from separating, a first separation preventing portion 27 is provided at the upper end portion of the first flow path defining portion 21. The first separation preventing portion 27 protrudes from the outer plate surface of the first flow path defining portion 21.

[0044] The second flow path defining portion 22 integrally includes a curved portion 22 a extending downward and outward from an end portion of the coolant tray 13 in the Y-axis direction, and a vertical portion 22 b extending downward from a lower end of the curved portion 22 a .

[0045] The bent portion 22a is disposed above the first flow path defining portion 21. A connecting flow path 25 is formed below the bent portion 22a to connect the ascending flow path 23 and the descending flow path 24 described later.

[0046] The vertical portion 22b is arranged outside the first flow path defining portion 21 in the Y-axis direction. The vertical portion 22b is arranged so as to face the first flow path defining portion 21. The vertical portion 22b is arranged so that its plate surface becomes a vertical surface. The vertical portion 22b is separated from the first flow path defining portion 21. The distance separating the vertical portion 22b from the first flow path defining portion 21 is longer than the distance separating the first flow path defining portion 21 from the baffle 17. A descending flow path 24 is formed between the vertical portion 22b and the first flow path defining portion 21, through which the refrigerant evaporated mainly in the liquid film heat transfer tube group 15 flows. That is, the descending flow path 24 is defined by the plate surface of the vertical portion 22b and the plate surface of the first flow path defining portion 21. As described above, the distance separating the vertical portion 22b from the first flow path defining portion 21 is longer than the distance separating the first flow path defining portion 21 from the baffle 17. Therefore, the flow path area of the ascending flow path 23 is smaller than the flow path area of the descending flow path 24 .

[0047] Furthermore, the outer plate surface of the vertical portion 22b faces the inner circumference of the cylindrical portion 11a. A pressure vessel flow path (frame flow path) 26 is formed between the vertical portion 22b and the cylindrical portion 11a, through which the refrigerant evaporated in the liquid film heat transfer tube group 15 flows. That is, the pressure vessel flow path 26 is defined by the plate surface of the vertical portion 22b and the inner circumference of the cylindrical portion 11a. The pressure vessel flow path 26 is defined by the inner circumference of the pressure vessel 11 (refer to FIG. Figure 1The pressure vessel flow path 26 is formed so that the refrigerant collides with the refrigerant flowing in. Furthermore, the distance between the vertical portion 22b and the inner circumferential surface of the cylindrical portion 11a is longer than the distance between the vertical portion 22b and the first flow path defining portion 21. Therefore, the flow path area of the pressure vessel flow path 26 is larger than the flow path area of the descending flow path 24.

[0048] The lower end of the vertical portion 22b is located above the lower end of the first flow path defining portion 21. The lower end of the vertical portion 22b is located below the upper end of the first flow path defining portion 21.

[0049] Furthermore, in order to prevent the circulating refrigerant from separating, a second separation preventing portion 28 is provided at the lower end portion of the vertical portion 22b. The second separation preventing portion 28 protrudes from the outer plate surface of the vertical portion 22b.

[0050] In the evaporator 10 configured as described above, the refrigerant flows as follows.

[0051] like Figure 1 As shown, in the evaporator 10, the refrigerant flows from the refrigerant inlet pipe 12 into the interior of the pressure vessel 11. The refrigerant flowing into the pressure vessel 11 is dispersed in the X-axis and Y-axis directions of the pressure vessel 11 by the refrigerant tray 13, and then falls downward through the multiple holes formed in the refrigerant tray 13.

[0052] The liquid refrigerant that drops from the refrigerant tray 13 contacts the second heat transfer tube 15a located at the top of the liquid film heat transfer tube group 15, coating the outer circumference of the second heat transfer tube 15a in a film-like manner. The refrigerant coating the outer circumference of the second heat transfer tube 15a in a film-like manner exchanges heat with the cooled water inside the second heat transfer tube 15a. The refrigerant that exceeds its boiling point through the heat exchange evaporates, and the refrigerant that does not exceed its boiling point further drops into the second heat transfer tube 15a located below. This heat exchange is repeated continuously. The refrigerant that does not evaporate through the heat exchange with the water in the second heat transfer tube 15a located at the bottom is stored in the storage section 11c located at the bottom of the pressure vessel 11. In this way, a liquid refrigerant pool is formed in the storage section 11c inside the pressure vessel 11. The liquid level S of this refrigerant pool is automatically adjusted to a predetermined height.

[0053] Meanwhile, as indicated by arrow A1, the refrigerant evaporating in the liquid film heat transfer tube group 15 bypasses the lower end of the baffle 17 and flows into the ascending flow path 23. The refrigerant flowing into the ascending flow path 23 flows from bottom to top within the ascending flow path 23. The refrigerant flowing through the ascending flow path 23 flows from the upper end of the ascending flow path 23 into the connecting flow path 25. As indicated by arrow A2, the refrigerant flowing into the connecting flow path 25 reverses its flow direction. The refrigerant that has reversed in the connecting flow path 25 flows into the descending flow path 24. As indicated by arrow A3, the refrigerant flowing into the descending flow path 24 flows from top to bottom within the descending flow path 24. The refrigerant discharged from the second flow path bypasses the lower end of the vertical portion 22b of the second flow path defining portion 22 and flows upward. At this point, as indicated by arrow A4, the refrigerant discharged from the second flow path collides with the collision position P on the inner circumferential surface of the cylindrical portion 11a of the pressure vessel 11. As indicated by arrow A5, the refrigerant that collides at the collision point P moves upward along the inner circumference of the cylindrical portion 11a within the pressure vessel flow path 26 and flows into the space above the refrigerant tray 13. The refrigerant that has flowed into the space above the refrigerant tray 13 is guided to the refrigerant outlet pipe 16 and discharged to the outside of the pressure vessel 11. The refrigerant discharged from the refrigerant outlet pipe 16 is drawn into the turbo compressor and compressed.

[0054] The first heat transfer tube 14a of the flooded heat transfer tube group 14 is immersed in the liquid refrigerant stored in the reservoir 11c. The cooled water flowing through the second heat transfer tube 15a exchanges heat with the refrigerant stored in the reservoir 11c. The refrigerant, having exchanged heat with the second heat transfer tube 15a, evaporates and is guided upward from the liquid surface S. The refrigerant evaporated in the film heat transfer tube group 15 and the flooded heat transfer tube group 14 is guided to the refrigerant outlet pipe 16. The refrigerant guided to the refrigerant outlet pipe 16 is discharged outside the pressure vessel 11. The refrigerant discharged from the refrigerant outlet pipe 16 is drawn into the turbo compressor and compressed.

[0055] According to this embodiment, the following effects are achieved.

[0056] In this embodiment, the refrigerant evaporated in the liquid film heat transfer tube group 15 flows through the gas-liquid separation flow path 20. The refrigerant flowing through the gas-liquid separation flow path 20 is then bent back from the top to the bottom in the connecting flow path 25. At this time, centrifugal force acts on the refrigerant flowing through the connecting flow path 25. This allows the refrigerant to be centrifugally separated into a gas phase refrigerant and a liquid phase refrigerant. This also reduces the occurrence of a phenomenon in which the refrigerant discharged from the refrigerant outlet pipe 16 to the outside of the pressure vessel 11 is accompanied by the liquid phase refrigerant (so-called entrainment).

[0057] Furthermore, in this embodiment, the gas-liquid separation flow path 20 is used to separate the refrigerant. This eliminates the need for expensive components such as a defogger and allows for gas-liquid separation of the refrigerant. Consequently, the initial cost of the evaporator 10 can be reduced.

[0058] Furthermore, in this embodiment, the flow area of the ascending flow path 23 connected to the upstream side of the connecting flow path 25 is smaller than the flow area of the descending flow path 24 connected to the downstream side of the connecting flow path 25. This increases the flow rate of the refrigerant flowing through the ascending flow path 23 connected to the upstream side of the connecting flow path 25. Consequently, the centrifugal force acting on the refrigerant as it flows through the connecting flow path 25 can be enhanced. Consequently, the refrigerant can be more effectively centrifugally separated into a gas phase and a liquid phase.

[0059] Furthermore, in this embodiment, the refrigerant flowing into the pressure vessel flow path 26 collides with the inner circumferential surface of the pressure vessel 11. The impact of the collision with the inner circumferential surface of the pressure vessel 11 causes the refrigerant to separate into a gaseous phase and a liquid phase (so-called collision separation). Therefore, the pressure vessel flow path 26 can separate the refrigerant into a gaseous phase and a liquid phase, thereby further reducing the occurrence of entrainment.

[0060] Furthermore, in this embodiment, the flow area of the pressure vessel flow path 26 is larger than the flow areas of the ascending flow path 23 and the descending flow path 24. This reduces the flow velocity of the refrigerant flowing through the pressure vessel flow path 26. In the pressure vessel flow path 26, the refrigerant flows from bottom to top. Therefore, by reducing the flow velocity, gravity can be more effectively utilized to separate the refrigerant gas and liquid. Consequently, entrainment can be further reduced.

[0061] Furthermore, the lower end of the first flow path defining portion 21 is positioned below the liquid surface S. Specifically, the lower end of the first flow path defining portion 21 is immersed in the refrigerant stored in the reservoir 11c. Consequently, the liquid refrigerant adhering to the first flow path defining portion 21 is guided along the first flow path defining portion 21 to the reservoir 11c. Consequently, the liquid refrigerant can be appropriately returned to the reservoir 11c.

[0062] Furthermore, a gap G is formed between the lower end of the first flow path defining portion 21 and the inner circumferential surface of the cylindrical portion 11a of the pressure vessel 11. Thus, the gap G allows the space inside the first flow path defining portion 21 to be connected to the space outside the first flow path defining portion 21. Therefore, even if the liquid-phase refrigerant, after gas-liquid separation, returns to the outside of the first flow path defining portion 21, the liquid-phase refrigerant that has returned to the reservoir 11c can be guided through the gap G to the space where the flooded heat transfer tube group 14 is located.

[0063] [Variation 1]

[0064] A modified example of this embodiment will be described. In the above description, the case where the baffle 17 is provided is described, but the present invention is not limited thereto. For example, Figure 2 As shown, the baffle 17 may be omitted. When the baffle 17 is omitted, the ascending flow path 23 and the connecting flow path 25 do not exist.

[0065] Even with this configuration, the refrigerant evaporated in the liquid film heat transfer tube group 15 is centrifugally separated by its vertical direction when flowing from the downflow path 24 into the pressure vessel path 26. Furthermore, as with the presence of the baffle 17, the refrigerant is separated by collision when flowing into the pressure vessel path 26, and by gravity while flowing through the pressure vessel path 26. Therefore, even without the baffle 17, entrainment can be minimized.

[0066] [Variation 2]

[0067] And, as Figure 3 As shown in FIG. 1 , a first discharge pipe (first discharge portion) 30 may be provided at the lower end of the vertical portion 22b of the second flow path defining portion 22. The first discharge pipe 30 extends along the Z-axis direction. Figure 4 and Figure 5 As shown in FIG. 1 , the first discharge pipe 30 is formed by dividing a cylindrical member into two along the longitudinal direction. Figure 3 and Figure 4 As shown in FIG. 1 , the upper end of the first discharge pipe 30 is connected to the lower end of the vertical portion 22b. Figure 3 As shown in FIG. 1 , the lower end of the first discharge pipe 30 is located below the liquid level S of the refrigerant stored in the storage portion 11c. Furthermore, the lower end of the first discharge pipe 30 is separated from the inner peripheral surface of the pressure container 11. Figure 4 As shown, the first discharge pipe 30 is provided in a part of the region in the X-axis direction of the vertical portion 22b. In addition, a plurality of first discharge pipes 30 may be provided. When a plurality of first discharge pipes 30 are provided, they may be arranged at predetermined intervals in the X-axis direction. Figure 5 As shown, the first discharge pipe 30 is arranged such that the cylindrical outer peripheral surface faces the upstream side of the refrigerant flow flowing through the gas-liquid separation flow path 20 .

[0068] According to this modification, the following effects are achieved.

[0069] While flowing through the gas-liquid separation flow path 20, a portion of the separated liquid-phase refrigerant adheres to the second flow path defining portion 22. In this modified example, the adhered refrigerant can be guided to the reservoir 11c via the first discharge pipe 30. The refrigerant guided to the reservoir 11c evaporates through heat exchange with the flooded heat transfer tube group 14. This allows the separated liquid-phase refrigerant to be guided to the flooded heat transfer tube group 14, thereby reducing the amount of refrigerant not supplied to each heat transfer tube group. Consequently, the performance of the evaporator 10 can be improved.

[0070] Furthermore, in this modified example, the first discharge pipe 30 is arranged so that the cylindrical outer peripheral surface faces the upstream side of the refrigerant flow flowing in the gas-liquid separation flow path 20. Thus, the first discharge pipe 30 can cover the refrigerant W along the first discharge pipe 30 from the upstream side (refer to FIG. Figure 5 ). Therefore, if Figure 4 As shown by the dotted arrows, the refrigerant flowing through the gas-liquid separation flow path 20 detours through the first discharge pipe 30. Therefore, the refrigerant W guided by the first discharge pipe 30 is less likely to be scattered by the refrigerant flowing through the gas-liquid separation flow path 20. Therefore, the liquid-phase refrigerant can be appropriately guided to the storage portion 11c.

[0071] Furthermore, the lower end of the first discharge pipe 30 is positioned below the liquid level S. Specifically, the lower end of the first discharge pipe 30 is immersed in the refrigerant stored in the reservoir 11c. Consequently, the liquid refrigerant adhering to the first discharge pipe 30 is guided along the first discharge pipe 30 to the reservoir 11c. Consequently, the liquid refrigerant can be appropriately returned to the reservoir 11c.

[0072] [Second embodiment]

[0073] Next, use Figure 6 A second embodiment of the present invention will be described.

[0074] This embodiment mainly differs from the first embodiment in the structure of the gas-liquid separation flow path. Other points are the same as the first embodiment, so the same components are denoted by the same reference numerals and detailed descriptions thereof are omitted.

[0075] The gas-liquid separation flow path 40 according to this embodiment includes a third flow path defining portion 41 disposed outside the baffle 17 in the Y-axis direction and provided above the lower end of the baffle 17, and a fourth flow path defining portion 42 provided above the third flow path defining portion 41. The gas-liquid separation flow path 40 is provided over substantially the entire area of the pressure vessel 11 in the X-axis direction.

[0076] The third flow path defining portion 41 integrally includes a plate-shaped first horizontal portion 41 a extending outward in the Y-axis direction from the outer plate surface of the baffle 17 and a plate-shaped first vertical portion 41 b extending upward by bending at a substantially right angle from the outer end portion of the first horizontal portion 41 a in the Y-axis direction.

[0077] The first horizontal portion 41a is arranged so that its plate surface is horizontal. The inner end of the first horizontal portion 41a in the Y-axis direction abuts or is close to the lower portion of the baffle 17. Furthermore, the outer end in the Y-axis direction extends to near the inner circumference of the cylindrical portion 11a.

[0078] The first vertical portion 41b is positioned so that its plate surface forms a vertical plane. The outer plate surface of the first vertical portion 41b faces the inner circumferential surface of the cylindrical portion 11a. A pressure vessel flow path (frame flow path) 43, which primarily flows through the refrigerant evaporated in the liquid film heat transfer tube group 15, is formed between the first vertical portion 41b and the cylindrical portion 11a. Specifically, the pressure vessel flow path 43 is defined by the plate surface of the first vertical portion 41b and the inner circumferential surface of the cylindrical portion 11a.

[0079] The fourth flow path defining portion 42 integrally includes a plate-shaped second horizontal portion 42a extending from the inner circumferential surface of the cylindrical portion 11a toward the inner side in the Y-axis direction, a plate-shaped second vertical portion 42b extending downward by bending downward at a substantially right angle from the inner end of the second horizontal portion 42a, a plate-shaped collecting portion 42c extending toward the outer side in the Y-axis direction by bending from the lower end of the second vertical portion 42b at a substantially right angle, and a plate-shaped third vertical portion 42d extending upward by bending from the outer end of the collecting portion 42c in the Y-axis direction at a substantially right angle.

[0080] The second horizontal portion 42a is configured so that its plate surface is horizontal. The second horizontal portion 42a is located above the upper end of the first vertical portion 41b. The outer end of the second horizontal portion 42a in the Y-axis direction abuts or is close to the inner circumferential surface of the cylindrical portion 11a. Furthermore, the inner end in the Y-axis direction extends to the vicinity of the baffle 17. The inner end in the Y-axis direction of the second horizontal portion 42a is separated from the baffle 17. Furthermore, a connecting flow path 47 is formed below the second horizontal portion 42a to connect the pressure vessel flow path 43 and the descending flow path 46 described later.

[0081] The second vertical portion 42b is positioned so that its plate surface forms a vertical plane. The inner plate surface of the second vertical portion 42b faces the baffle 17. An ascending flow path 44 is formed between the second vertical portion 42b and the baffle 17, primarily through which refrigerant evaporating in the liquid film heat transfer tube group 15 flows. Specifically, the ascending flow path 44 is defined by the second vertical portion 42b and the baffle 17. The lower end of the second vertical portion 42b is positioned above the first horizontal portion 41a. The lower end of the second vertical portion 42b is separated from the first horizontal portion 41a.

[0082] The collecting portion 42c is arranged so that the plate surface becomes a horizontal plane. The collecting portion 42c is arranged above the first horizontal portion 41a. Furthermore, the collecting portion 42c is arranged below the upper end of the first vertical portion 41b. The lower surface of the collecting portion 42c is opposite to the upper surface of the first horizontal portion 41a. A horizontal flow path 45 is formed between the lower surface of the collecting portion 42c and the upper surface of the first horizontal portion 41a. In other words, the horizontal flow path 45 is defined by the collecting portion 42c and the first horizontal portion 41a. A space for collecting the liquid-phase refrigerant that has been centrifugally separated is formed between the upper surface of the collecting portion 42c and the lower surface of the second horizontal portion 42a. The inner side of this space in the Y-axis direction is defined by the second vertical portion 42b.

[0083] The collecting portion 42c is provided with a second discharge pipe (second discharge portion) 50 that guides the collected liquid refrigerant to the storage portion 11c. The upper end of the second discharge pipe 50 is connected to the upper surface of the collecting portion 42c, which differs from the first discharge pipe 30 described in Modification 2 of the first embodiment. In other respects, the second discharge pipe 50 is substantially the same as the first discharge pipe 30, and therefore a detailed description of the second discharge pipe 50 will be omitted.

[0084] Furthermore, a third discharge pipe 51 is provided in the horizontal flow path 45 to guide the liquid refrigerant to the reservoir 11c. The upper end of the third discharge pipe 51 is connected to the upper surface of the first horizontal portion 41a, differing from the first discharge pipe 30 described in Modification 2 of the first embodiment. Since the third discharge pipe 51 is substantially identical to the first discharge pipe 30 in other respects, a detailed description thereof will be omitted. The third discharge pipe 51 is provided near the vertically lower portion of the ascending flow path 44.

[0085] The third vertical portion 42d is positioned so that its plate surface forms a vertical plane. The outer plate surface of the third vertical portion 42d faces the inner plate surface of the second vertical portion 42b. A descending flow path 46 is formed between the third vertical portion 42d and the second vertical portion 42b, primarily for the flow of refrigerant evaporated in the liquid film heat transfer tube group 15. Specifically, the descending flow path 46 is defined by the third vertical portion 42d and the first vertical portion 41b. The flow area of the descending flow path 46 is smaller than that of the ascending flow path 44.

[0086] The upper end of the third vertical portion 42d is located below the second horizontal portion 42a. The upper end of the third vertical portion 42d is separated from the second horizontal portion 42a. Furthermore, the upper end of the third vertical portion 42d is located below the upper end of the first vertical portion 41b.

[0087] Next, the refrigerant circulation method in this embodiment will be described. Except for the refrigerant flow evaporated in each heat transfer tube group, the flow is the same as that in the first embodiment, and therefore the description thereof will be omitted.

[0088] In this embodiment, as indicated by arrow A6, the refrigerant evaporating in the liquid film heat transfer tube group 15 detours around the lower end of the baffle 17 and collides with the inner circumferential surface of the cylindrical portion 11a of the pressure vessel 11 at the collision point P. As indicated by arrow A7, the refrigerant colliding at the collision point P moves upward along the inner circumferential surface of the cylindrical portion 11a within the pressure vessel flow path 43. The refrigerant flowing through the pressure vessel flow path 43 flows from the upper end of the pressure vessel flow path 43 into the connecting flow path 47. The refrigerant flowing into the connecting flow path 47 then reverses its flow direction. Because the density of the liquid phase refrigerant is higher than that of the gas phase refrigerant, it makes a sharp turn when it reverses, as indicated by arrow A8. The sharply turned liquid phase refrigerant is captured in the collection portion 42c. Meanwhile, the lower-density gas phase refrigerant makes a slight turn, as indicated by arrow A9, and flows into the downflow path 46. The refrigerant flowing into the downflow path 46 flows from top to bottom within the downflow path 46. The refrigerant flowing through the descending flow path 46 flows through the horizontal flow path 45. The refrigerant flowing through the horizontal flow path 45 flows into the ascending flow path 44. As indicated by arrow A10, the refrigerant flowing into the ascending flow path 44 flows from bottom to top within the ascending flow path 44. The refrigerant flowing through the ascending flow path 44 flows into the space above the refrigerant tray 13. The refrigerant flowing into the space above the refrigerant tray 13 is guided to the refrigerant outlet pipe 16 and discharged to the outside of the pressure vessel 11.

[0089] According to this embodiment, the following effects are achieved.

[0090] In this embodiment, the refrigerant evaporated in the liquid film heat transfer tube group 15 is first directed to the pressure vessel flow path 43. This allows the refrigerant to collide with the inner circumferential surface of the pressure vessel 11 for collision separation before centrifugal separation in the connecting flow path 47. This increases the velocity of the refrigerant colliding with the inner circumferential surface of the pressure vessel 11. Consequently, the refrigerant can be more efficiently separated into gas and liquid through collision separation.

[0091] Furthermore, in this embodiment, the collecting portion 42c for collecting the separated liquid-phase refrigerant is provided on the downstream side of the connected flow path (downward flow path 46). This allows the centrifugally separated liquid phase to be appropriately collected.

[0092] Furthermore, in this embodiment, the collected refrigerant is guided to the reservoir 11c via the second discharge pipe 50. The refrigerant guided to the reservoir 11c evaporates through heat exchange with the flooded heat transfer tube group 14. This allows the liquid phase of the refrigerant, which has undergone gas-liquid separation, to be guided to the flooded heat transfer tube group 14, thereby reducing the amount of refrigerant not supplied to each heat transfer tube group. Consequently, the performance of the evaporator 10 can be improved.

[0093] [Variation 3]

[0094] Alternatively, the collecting portion 42c may be inclined relative to the horizontal plane in the X-axis direction. In this case, if the collecting portion 42c is inclined so that the portion where the second discharge pipe 50 is located is lowered, the liquid refrigerant is concentrated in the second discharge pipe 50, thereby more effectively returning the liquid refrigerant to the reservoir 11c. Furthermore, if multiple second discharge pipes 50 are arranged along the X-axis, the collecting portion 42c may have multiple inclined surfaces so that the portion where each second discharge pipe 50 is located is lowered.

[0095] [Variation 4]

[0096] And, as Figure 7 As shown, the third flow path defining portion can be formed by a curved surface. The third flow path defining portion (curved portion) 60 according to this modification integrally includes a first portion 61 extending from the lower end of the baffle 17 outward in the Y-axis direction and curving upward, and a second portion 62 extending from the upper end of the first portion 61 inward in the Y-axis direction and curving upward. The upper end of the second portion 62 extends to the vicinity of the second horizontal portion 42a. The upper end of the second portion 62 is separated from the second horizontal portion 42a. Furthermore, the upper end of the second portion 62 is separated from the second vertical portion 42b.

[0097] Furthermore, the third discharge pipe 51 is provided in the first portion 61 . Specifically, it is provided in the lower end of the first portion 61 .

[0098] In this modified example, as indicated by arrow A11, the refrigerant evaporated in the liquid film heat transfer tube group 15 flows between the third flow path defining portion 60 and the inner circumferential surface of the pressure vessel 11. Next, as indicated by arrow A12, the refrigerant flows between the upper end of the second portion 62 and the second horizontal portion 42a, and between the upper end of the second portion 62 and the second vertical portion 42b. Next, as indicated by arrow A13, the refrigerant flows between the first portion 61 and the third vertical portion 42d, flowing along the first portion 61. Then, as indicated by arrow A14, the refrigerant flows into the ascending flow path 44 and into the space above the refrigerant tray 13. The refrigerant flowing into the space above the refrigerant tray 13 is guided to the refrigerant outlet pipe 16 and discharged to the exterior of the pressure vessel 11.

[0099] In this modification, the third flow path defining portion 60 is curved. This reduces the pressure loss of the refrigerant flowing through the gas-liquid separation flow path, thereby allowing the refrigerant to be appropriately guided to the refrigerant outlet pipe 16 .

[0100] Furthermore, because the third flow path defining portion 60 is curved, even if the liquid-phase refrigerant that has undergone gas-liquid separation falls anywhere on the upper surface of the first portion 61, the liquid-phase refrigerant can be guided to the third discharge pipe 51. This allows, for example, a larger area for guiding the refrigerant to the third discharge pipe 51 than in the second embodiment where the third flow path defining portion is formed solely of a flat plate member. Consequently, the liquid-phase refrigerant can be appropriately returned to the storage portion 11c.

[0101] In addition, the present invention is not limited to the above-described embodiment, and can be modified appropriately within a scope not departing from the gist of the present invention.

[0102] For example, in the above-described embodiments, an example is described in which a flow path for upward refrigerant flow is connected to the upstream side of the connecting flow path, and a flow path for downward refrigerant flow is connected to the downstream side. However, the present invention is not limited to this. For example, a flow path for downward refrigerant flow may also be connected to the upstream side of the connecting flow path.

[0103] Furthermore, for example, while the above embodiments describe the use of a refrigerant tray as a means for supplying refrigerant to a liquid film heat transfer tube assembly, the present invention is not limited thereto. The refrigerant supplying means may be, for example, a piping-like member extending along the X-axis, as long as it is capable of supplying refrigerant to the liquid film heat transfer tube assembly.

[0104] The evaporator described in the present embodiment described above can be understood, for example, as follows.

[0105] An evaporator according to one embodiment of the present invention comprises: a frame 11 having a refrigerant outlet 16 for discharging evaporated refrigerant and constituting an outer shell; a first heat transfer tube group 14 housed in the frame and immersed in liquid-phase refrigerant stored in a storage portion 11 c provided in a lower portion of the frame, and having a plurality of first heat transfer tubes 14 a through which the cooling medium circulates; and a second heat transfer tube group 15 housed in the frame and provided at a position above a liquid level S of the liquid-phase refrigerant stored in the lower portion of the frame. And it has a plurality of second heat transfer tubes 15a through which the cooling medium circulates; a refrigerant supply part 13, which is accommodated in the frame and supplies liquid refrigerant to the second heat transfer tube group from above; and a flow path 20, which guides the refrigerant evaporated in the second heat transfer tube group to the refrigerant outlet, and the flow path has: a first flow path 23, for the refrigerant to circulate from bottom to top; a second flow path 24, for the refrigerant to circulate from top to bottom; and a connecting flow path 25, which connects the first flow path and the second flow path and returns the refrigerant.

[0106] In the above structure, the refrigerant evaporated in the second heat transfer tube group circulates in the flow path. The refrigerant flowing in the flow path bends back from top to bottom or from bottom to top in the connecting flow path. At this time, centrifugal force acts on the refrigerant flowing in the connecting flow path. This allows the refrigerant to be centrifugally separated into a gaseous phase and a liquid phase. This reduces the occurrence of liquid refrigerant being carried along with the refrigerant discharged from the refrigerant outlet to the outside of the housing (so-called entrainment).

[0107] Furthermore, in the above-described structure, the refrigerant gas-liquid separation is performed using the flow path. This eliminates the need for expensive components such as a demister, and allows for gas-liquid separation of the refrigerant, thereby reducing initial costs.

[0108] In addition, the first flow path and the second flow path are names for convenience, and "first" and "second" do not refer to the order in which the refrigerant flows.

[0109] Furthermore, in the evaporator according to one aspect of the present invention, the flow area of the first flow path or the second flow path connected to the upstream side of the connecting flow path is smaller than the flow area of the first flow path or the second flow path connected to the downstream side of the connecting flow path.

[0110] In the above structure, the cross-sectional area of the flow path upstream of the connecting flow path is reduced. This increases the flow rate of the refrigerant flowing through the flow path upstream of the connecting flow path. Consequently, the centrifugal force acting on the refrigerant as it flows through the connecting flow path is enhanced. Consequently, the refrigerant can be more effectively centrifugally separated into a gaseous phase and a liquid phase.

[0111] Furthermore, in the evaporator according to one aspect of the present invention, the flow path includes a frame flow path 26 partially defined by the inner peripheral surface of the frame, and the frame flow path is arranged at a position where the inflowing refrigerant collides with the inner peripheral surface of the frame.

[0112] In the above structure, the refrigerant flowing into the frame flow path collides with the inner circumferential surface of the frame. The impact of the collision with the inner circumferential surface of the frame causes the refrigerant to separate into gas and liquid phases (so-called collision separation). Therefore, the frame flow path can be used to separate the refrigerant into gaseous and liquid phases. This can further reduce the occurrence of refrigerant discharged from the refrigerant outlet to the outside of the frame accompanied by liquid phase refrigerant (so-called entrainment).

[0113] Furthermore, in the evaporator according to the aspect of the present invention, the frame flow path is provided upstream of the connecting flow path.

[0114] In this structure, the refrigerant can be subjected to collision separation by colliding with the inner circumferential surface of the frame before centrifugal separation using the connection portion. This accelerates the velocity of the refrigerant colliding with the inner circumferential surface of the frame. Consequently, collision separation can more effectively separate the refrigerant gas and liquid.

[0115] Furthermore, in the evaporator according to one aspect of the present invention, the flow path is provided with the first discharge portion 30 for guiding the liquid-phase refrigerant to the storage portion.

[0116] In this configuration, as the refrigerant flows through the flow path, the liquid phase of the refrigerant, which has undergone gas-liquid separation, adheres to the flow path. The adhered refrigerant is directed to the reservoir via the first discharge portion. The refrigerant directed to the reservoir evaporates through heat exchange with the first heat transfer tube group. This allows the liquid phase of the refrigerant, which has undergone gas-liquid separation, to be directed to the first heat transfer tube group, thereby reducing the amount of refrigerant not supplied to each heat transfer tube group. Consequently, the performance of the evaporator can be improved.

[0117] Alternatively, the first discharge portion can be formed by, for example, splitting a cylindrical member into two along its length, with the cylindrical surface positioned upstream of the refrigerant flow in the flow path. This configuration allows the first discharge portion to cover the refrigerant guided by the first discharge portion from the upstream side of the refrigerant flow in the flow path. This prevents the refrigerant guided by the first discharge portion from being scattered by the refrigerant in the flow path. Consequently, the liquid refrigerant can be appropriately guided to the storage portion.

[0118] Furthermore, the first discharge portion may be arranged such that its upper end is connected to the flow path and its lower end is located in the refrigerant stored in the storage portion and is separated from the inner peripheral surface of the housing.

[0119] Furthermore, in the evaporator according to one aspect of the present invention, a collecting portion 42 c for collecting the separated liquid-phase refrigerant is provided on the connected downstream flow path in the connecting flow path.

[0120] The density of the liquid refrigerant centrifugally separated at the connection portion is higher than the density of the separated gaseous refrigerant. Consequently, the separated liquid refrigerant makes a larger turn than the gaseous refrigerant when it returns. In other words, the liquid refrigerant flows near the downstream flow path when it returns. In the above structure, the collection portion for collecting the separated liquid refrigerant is located on the downstream side of the connected flow path. This allows for the appropriate collection of the centrifugally separated liquid phase.

[0121] Furthermore, in the evaporator according to one aspect of the present invention, the collecting portion is provided with a second discharge portion 50 that guides the collected liquid-phase refrigerant to the storage portion.

[0122] In this configuration, the collected refrigerant is guided to the reservoir via the second discharge portion. The refrigerant guided to the reservoir evaporates through heat exchange with the first heat transfer tube group. This allows the liquid phase of the refrigerant, which has undergone gas-liquid separation, to be guided to the first heat transfer tube group, thereby reducing the amount of refrigerant not supplied to each heat transfer tube group. This improves evaporator performance.

[0123] Furthermore, in the evaporator according to the aspect of the present invention, the collecting portion is inclined so that a position where the second discharge portion is provided becomes lower.

[0124] In the above structure, the collection section is tilted so that the position where the second discharge section is provided becomes lower. As a result, the liquid refrigerant collected by the collection section flows toward the second discharge section. Therefore, the collected refrigerant can be more appropriately guided to the storage section via the second discharge section.

[0125] Furthermore, in the evaporator according to one aspect of the present invention, the flow path includes a curved portion 60 that defines a curvature of the surface of the flow path.

[0126] In the above structure, the flow path has a curved portion. Thus, the pressure loss of the refrigerant flowing in the flow path is reduced at the curved portion. Therefore, the refrigerant can be appropriately guided to the refrigerant outlet.

[0127] Explanation of symbols

[0128] 10 - Evaporator, 11 - Pressure vessel (frame), 11a - Cylindrical portion, 11c - Storage portion, 12 - Refrigerant inlet pipe, 13 - Refrigerant tray (refrigerant supply portion), 14 - Flooded heat transfer tube group (first heat transfer tube group), 14a - First heat transfer tube, 15 - Liquid film heat transfer tube group (second heat transfer tube group), 15a - Second heat transfer tube, 16 - Refrigerant outlet pipe (refrigerant outlet), 17 - Baffle, 20 - Gas-liquid separation flow path (flow path), 21 - First flow path defining portion, 22 - Second flow path defining portion, 22a - Bend, 22b - Vertical portion, 23 - Ascending flow path (first flow path), 24 - Descending flow path (second flow path), 25 - Connecting flow path, 26 - Pressure vessel flow path (frame flow path) , 27-the first peeling prevention portion, 28-the second peeling prevention portion, 30-the first discharge pipe (the Lth discharge portion), 40-gas-liquid separation flow path, 41-the third flow path defining portion, 41a-the first horizontal portion, 41b-the first vertical portion, 42-the fourth flow path defining portion, 42a-the second horizontal portion, 42b-the second vertical portion, 42c-the collecting portion, 42d-the third vertical portion, 43-pressure vessel flow path (frame flow path), 44-ascending flow path, 45-horizontal flow path, 46-descending flow path, 47-connecting flow path, 50-the second discharge pipe (the second discharge portion), 51-the third discharge pipe, 60-the third flow path defining portion, 61-the first part, 62-the second part, G-gap, P-collision position, S-liquid level.

Claims

1. An evaporator comprising: a frame having a refrigerant outlet for discharging evaporated refrigerant and constituting an outer shell; a first heat transfer tube group housed in the frame and immersed in the liquid refrigerant stored in a storage portion provided at a lower portion of the frame, and comprising a plurality of first heat transfer tubes through which the cooling medium circulates; a second heat transfer tube group housed in the frame and disposed above a liquid level of the liquid refrigerant stored in a lower portion of the frame, and comprising a plurality of second heat transfer tubes through which the cooling medium circulates; a refrigerant supply unit, housed in the frame, for supplying liquid-phase refrigerant to the second heat transfer tube group from above; and a flow path for guiding the refrigerant evaporated in the second heat transfer tube group to the refrigerant outlet, The flow path includes: a first flow path through which the refrigerant flows from bottom to top; a second flow path through which the refrigerant flows from top to bottom; and a connecting flow path that connects the first flow path and the second flow path and returns the refrigerant.

2. The evaporator according to claim 1, wherein The flow path area of the first flow path or the second flow path connected to the upstream side of the connecting flow path is smaller than the flow path area of the first flow path or the second flow path connected to the downstream side of the connecting flow path.

3. The evaporator according to claim 1 or 2, wherein: The flow path includes a frame flow path partially defined by the inner peripheral surface of the frame, The inner peripheral surface of the frame is arranged at a position where the inflowing refrigerant collides with the frame flow path.

4. The evaporator according to claim 3, wherein The frame flow path is provided at an upstream side of the connecting flow path.

5. The evaporator according to claim 1 or 2, wherein: The flow path is provided with a first discharge portion that guides the liquid-phase refrigerant to the storage portion.

6. The evaporator according to claim 1 or 2, wherein: In the connecting flow path, a collecting portion for collecting the separated liquid-phase refrigerant is provided on the connected downstream flow path side.

7. The evaporator according to claim 6, wherein The collecting portion is provided with a second discharge portion that guides the collected liquid-phase refrigerant to the storage portion.

8. The evaporator according to claim 7, wherein The collecting portion is inclined so that the position where the second discharge portion is provided becomes lower.

9. The evaporator according to claim 1 or 2, wherein: The flow path has a curved portion that defines a curvature of a surface of the flow path.

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