Heat exchangers and refrigeration units

Abstract

A heat exchanger is provided in a refrigeration device (R) configured to perform a refrigeration cycle in which the evaporation pressure of a refrigerant is lower than atmospheric pressure. The heat exchanger functions as an evaporator and includes a housing (20) and a plate bundle (40). The housing (20) forms an internal space (21), and the plate bundle (40) is arranged in the internal space (21) and includes a plurality of heat transfer plates (50a, 50b).

Description

Technical Field

[0001] The present disclosure relates to a heat exchanger and a refrigeration device. Background Art

[0002] Refrigeration systems that perform a refrigeration cycle are widely known. The refrigeration system disclosed in Patent Document 1 includes a refrigerant circuit comprising a compressor, a condenser, an expansion valve, and an evaporator. In this refrigeration system, the refrigerant used is, for example, R-1233zd (1-chloro-3,3,3-trifluoropropene). R-1233zd is a so-called low-pressure refrigerant.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 2019-45135 Summary of the Invention

[0006] -Technical problem to be solved by the invention-

[0007] In the refrigeration device disclosed in Patent Document 1, the refrigerant exchanges heat with a predetermined heat medium in the evaporator. In such a refrigeration device, when a refrigeration cycle is performed in which the evaporation pressure of the refrigerant is lower than atmospheric pressure, the volume of the gaseous refrigerant evaporating within the heat exchanger increases. If this results in a decrease in the contact area between the liquid refrigerant and the heat transfer portion (heat transfer tube), the heat exchange performance between the refrigerant and the heat medium in the evaporator decreases. Consequently, there is a problem: to maintain the performance of the heat exchanger, the size of the heat exchanger must be increased.

[0008] An object of the present disclosure is to provide a heat exchanger capable of suppressing an increase in size even when used in a refrigeration apparatus that performs a refrigeration cycle in which the evaporation pressure of a refrigerant is lower than atmospheric pressure.

[0009] -Technical solutions to solve technical problems-

[0010] The first aspect is a heat exchanger,

[0011] It is provided in a refrigeration device R and functions as an evaporator. The refrigeration device R is configured to perform a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than the atmospheric pressure.

[0012] The heat exchanger includes a shell 20 and a plate bundle 40. The shell 20 forms an inner space 21.

[0013] The plate bundle 40 is arranged in the inner space 21 and includes a plurality of heat transfer plates 50 a, 50 b.

[0014] In the first aspect, a plate bundle 40 is provided within the heat exchanger housing 20. By integrating multiple heat transfer plates 50a and 50b within the plate bundle 40, the heat transfer area can be increased while maintaining a relatively small volume. Therefore, even when the heat exchanger is used as an evaporator in a refrigeration system operating a refrigeration cycle in which the refrigerant evaporation pressure is lower than atmospheric pressure, sufficient heat exchanger performance can be maintained, and an increase in size of the heat exchanger can be suppressed.

[0015] According to a second aspect, the heat exchanger according to the first aspect is provided in a refrigeration device R configured to perform a refrigeration cycle in which the evaporation pressure of a refrigerant at a temperature of 0° C. or higher is lower than atmospheric pressure.

[0016] In the second aspect, even at temperatures above 0°C, the refrigerant's evaporation pressure is lower than atmospheric pressure. Therefore, the heat exchange performance between the refrigerant and the heat medium in the heat exchanger is likely to decrease due to the aforementioned factors. However, since the heat exchanger includes the plate bundle 40, it is possible to maintain heat exchanger performance while suppressing an increase in size.

[0017] According to a third aspect, the heat exchanger according to the second aspect is provided in a refrigeration device R using 1-chloro-3,3,3-trifluoropropene as the refrigerant.

[0018] In the third aspect, in a heat exchanger used in a refrigeration device R having a low GWP (Global Warming Potential), it is possible to suppress an increase in the size of the heat exchanger while ensuring the performance of the heat exchanger.

[0019] According to a fourth aspect, based on any one of the first to third aspects, a pitch P between the plurality of heat transfer plates 50a, 50b is greater than 1.2 mm.

[0020] In the evaporator of a refrigeration device R, which operates a refrigeration cycle in which the refrigerant's evaporation pressure is lower than atmospheric pressure, bubbles formed by evaporating gaseous refrigerant tend to increase in volume. Therefore, if the spacing P between adjacent heat transfer plates 50a, 50b is too narrow, bubbles are more likely to diffuse along the heat transfer plates 50a, 50b in the refrigerant flow path formed between the adjacent heat transfer plates 50a, 50b. As a result, the contact area between the heat transfer plates 50a, 50b and the gaseous refrigerant increases, while the contact area between the heat transfer plates 50a, 50b and the liquid refrigerant decreases. This reduces the heat exchange performance between the refrigerant and the designated heat medium in the plate bundle 40.

[0021] In contrast, in the fourth aspect, the pitch P between the plurality of heat transfer plates 50a, 50b in the plate bundle 40 is set to 1.2 mm or greater. This reduces the diffusion of gaseous refrigerant along the heat transfer plates 50a, 50b in the refrigerant flow path between adjacent heat transfer plates 50a, 50b. As a result, the reduction in contact area between the heat transfer plates 50a, 50b and the liquid refrigerant due to the generation of bubbles can be suppressed, thereby minimizing degradation in heat exchanger performance.

[0022] The fifth aspect is that, based on the fourth aspect, the spacing P is greater than 1.5 mm.

[0023] In the fifth aspect, by setting the pitch P to 1.5 mm or more, it is possible to further suppress a decrease in the contact area between the heat transfer plates 50 a and 50 b and the liquid refrigerant, thereby further suppressing a decrease in the performance of the heat exchanger.

[0024] The sixth aspect is that, based on the fifth aspect, the spacing P is less than 2.1 mm.

[0025] If the pitch P is too large, the flow velocity of the refrigerant in the refrigerant flow path between the adjacent heat transfer plates 50a and 50b will decrease, resulting in a decrease in the performance of the heat exchanger.

[0026] In contrast, in the sixth aspect, by setting the pitch P between the plurality of heat transfer plates 50a and 50b to 2.1 mm or less, it is possible to suppress a decrease in the flow velocity of the refrigerant and thereby suppress a decrease in the performance of the heat exchanger.

[0027] According to a seventh aspect, in addition to any one of the first to sixth aspects, a roughened portion 80 is formed on the surface of the heat transfer plates (50a, 50b).

[0028] The heat transfer plates 50a and 50b of the seventh aspect have roughened surfaces formed with roughened portions 80. The roughened portions 80 improve wettability of the surfaces of the heat transfer plates 50a and 50b by the liquid refrigerant, thereby improving heat exchanger performance.

[0029] The eighth aspect is a refrigeration device comprising the heat exchanger 10 according to any one of the first to seventh aspects,

[0030] Furthermore, the refrigeration cycle is configured to be capable of performing a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than the atmospheric pressure.

[0031] In the eighth aspect, a refrigeration apparatus can be provided that can perform a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than the atmospheric pressure, while suppressing an increase in the size of the heat exchanger 10 . BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1is a schematic diagram of a refrigeration device according to an embodiment;

[0033] Figure 2 It is the main view of the heat exchanger;

[0034] Figure 3 It is along Figure 2 The cross-sectional view taken along line II-II;

[0035] Figure 4 It is a simplified diagram of a part of the longitudinal section of the plate bundle;

[0036] Figure 5 It is the main view of the first plate;

[0037] Figure 6 It is the main view of the second plate;

[0038] Figure 7 is a simplified diagram showing the flow of heat medium within the plate bundle;

[0039] Figure 8 is a simplified diagram showing the flow of heat medium on the heat transfer plate;

[0040] Figure 9 It is a simplified diagram of a portion of the longitudinal section of the plate bundle, with dimensions marked;

[0041] Figure 10 This chart evaluates the relationship between heat flux and heat transfer coefficient for heat exchangers with multiple heat transfer plates at different spacings.

[0042] Figure 11 This is an enlarged longitudinal sectional view of a portion of a plate bundle of a heat exchanger according to Modification 1. DETAILED DESCRIPTION

[0043] The present embodiment will be described below with reference to the accompanying drawings. It should be noted that the following embodiments are merely preferred examples in nature and are not intended to limit the present invention, its application objects, or its scope of use.

[0044] (Implementation Method)

[0045] The heat exchanger 10 disclosed in the present invention is a plate and shell heat exchanger. The heat exchanger 10 is provided in a refrigeration device R. The refrigeration device R in this example is a cooling unit that generates chilled water.

[0046] (1) Overview of Refrigeration Equipment

[0047] like Figure 1As shown, refrigeration device R has a refrigerant circuit 1 filled with refrigerant. Refrigerant circuit 1 includes a compressor 2, a radiator 3, a pressure reducing mechanism 4, and an evaporator 5. The heat exchanger 10 of the present disclosure constitutes evaporator 5. Refrigerant circuit 1 performs a vapor compression refrigeration cycle. Compressor 2 is a screw compressor, but may also be other types of compressors, such as a turbo compressor, a scroll compressor, a swing piston compressor, or a rotary compressor.

[0048] In the refrigeration cycle, the refrigerant compressed in the compressor 2 dissipates heat in the radiator 3. The refrigerant after dissipating heat is decompressed in the decompression mechanism 4 and evaporates in the evaporator 5. The evaporated refrigerant is sucked into the compressor 2.

[0049] It should be noted that the refrigerant circuit 1 may also include a switching mechanism such as a four-way switching valve for switching the flow path of the refrigerant. In this case, the heat exchanger 10 functions as an evaporator or a condenser.

[0050] (2) Overview of heat exchanger

[0051] like Figure 2 and Figure 3 As shown, the heat exchanger 10 includes a housing 20 and a plate bundle 40. The plate bundle 40 is housed within the interior space 21 of the housing 20. Liquid refrigerant flows into the interior space 21 of the housing 20. The liquid refrigerant exchanges heat with the heat medium flowing within the plate bundle 40. The heat exchanger 10 functions as an evaporator by evaporating the refrigerant flowing into the interior space 21 of the housing 20. Examples of the heat medium include water and antifreeze.

[0052] (2-1) Shell

[0053] The shell 20 is a cylindrical, sealed container with a relatively long horizontal length. The shell 20 includes a main body 20a, a first side wall 20b, and a second side wall 20c. The main body 20a is cylindrical. The first side wall 20b is circular and closes the left end of the main body 20a. The second side wall 20c is circular and closes the right end of the main body 20a. The main body 20a, the first side wall 20b, and the second side wall 20c define an internal space 21 in the shell 20. Liquid refrigerant is stored in the internal space 21.

[0054] The trunk portion 20a has a refrigerant inlet 32 and a refrigerant outlet 33. The refrigerant inlet 32 is located at the bottom of the trunk portion 20a. Refrigerant is introduced into the internal space 21 through the refrigerant inlet 32. The refrigerant outlet 33 is located at the top of the trunk portion 20a. Refrigerant evaporated in the internal space 21 is guided out of the housing 20 through the refrigerant outlet 33. The refrigerant inlet 32 and the refrigerant outlet 33 are connected to the refrigerant circuit via piping.

[0055] The first side wall 20b is provided with a heat medium inlet 23 and a heat medium outlet 24. These are tubular components. In this example, the heat medium inlet 23 is located above the heat medium outlet 24. This means that the heat medium flows from the top to the bottom of the plate bundle 40. It should be noted that the heat medium inlet 23 can also be located below the heat medium outlet 24. In this case, the heat medium flows from the bottom to the top of the plate bundle 40.

[0056] The heat medium inlet 23 penetrates substantially the center portion of the first side wall 20 b and is connected to the heat medium introduction path 43 of the plate bundle 40 . The heat medium inlet 23 supplies heat medium to the plate bundle 40 .

[0057] The heat medium outlet 24 passes through the first side wall 20b approximately midway between the heat medium inlet 23 and the lower end of the first side wall 20b. The heat medium outlet 24 is connected to the heat medium outlet path 44 of the plate bundle 40 and draws heat medium from the plate bundle.

[0058] (2-2) Plate bundle

[0059] The plate bundle 40 is composed of a plurality of heat transfer plates 50a, 50b stacked and joined together in a transverse direction. The plate bundle 40 is housed in the internal space 21 of the housing 20 with the stacking direction of the heat transfer plates 50a, 50b being transverse.

[0060] like Figure 2 As shown, the heat transfer plates 50a and 50b that constitute the plate bundle 40 are approximately semicircular plate-shaped components. The width of the heat transfer plates 50a and 50b increases as they approach the upper side. The plate bundle 40 is arranged near the bottom of the internal space 21 of the shell 20, with the arc-shaped edges of the heat transfer plates 50a and 50b facing downward. The inner surface of the shell 20 is provided with a protruding support portion that supports the plate bundle 40, which is not shown. When the plate bundle 40 is accommodated in the internal space 21 of the shell 20, the plate bundle 40 is separated from the inner surface of the shell 20, and a gap 25 is formed between the downward-facing edges of the heat transfer plates 50a and 50b that constitute the plate bundle 40 and the inner surface of the shell 20. Within the internal space 21, an upper space 21a is formed in the upper portion of the plate bundle 40.

[0061] like Figure 4 As shown, in the plate bundle 40, a first plate 50a and a second plate 50b having different shapes are provided as heat transfer plates 50a and 50b. The plate bundle 40 includes a plurality of first plates 50a and a plurality of second plates 50b. In the plate bundle 40, the first plates 50a and the second plates 50b are alternately stacked. In the following description, the first plates 50a and the second plates 50b are referred to as Figure 4 Set the left side of the surface as the surface, and Figure 4 Set the right side of the face as the back side.

[0062] (2-3) Heat medium inlet and outlet

[0063] The first plate 50a is formed with a lower convex portion 51a and an upper convex portion 53a. The lower convex portion 51a and the upper convex portion 53a are both circular portions that bulge toward the surface of the first plate 50a. The lower convex portion 51a and the upper convex portion 53a are both formed in the center portion of the first plate 50a in the width direction. The lower convex portion 51a is formed in the lower portion of the first plate 50a. The upper convex portion 53a is formed in the upper portion of the first plate 50a. A first lower hole 52a is formed in the center portion of the lower convex portion 51a. A first upper hole 54a is formed in the center portion of the upper convex portion 53a. The first lower hole 52a and the first upper hole 54a are both circular holes that penetrate the first plate 50a in the thickness direction.

[0064] The second plate 50b is formed with a lower recess 51b and an upper recess 53b. Both the lower recess 51b and the upper recess 53b are circular portions that bulge toward the back side of the second plate 50b. The lower recess 51b and the upper recess 53b are both formed in the center of the second plate 50b in the width direction. The lower recess 51b is formed in the lower portion of the second plate 50b. The upper recess 53b is formed in the upper portion of the second plate 50b. A second lower hole 52b is formed in the center of the lower recess 51b. A second upper hole 54b is formed in the center of the upper recess 53b. Both the second lower hole 52b and the second upper hole 54b are circular holes that penetrate the second plate 50b in the thickness direction.

[0065] On the second plate 50b, a lower recess 51b is formed at a position corresponding to the lower protrusion 51a of the first plate 50a, and an upper recess 53b is formed at a position corresponding to the upper protrusion 53a of the first plate 50a. Furthermore, on the second plate 50b, a second lower hole 52b is formed at a position corresponding to the first lower hole 52a of the first plate 50a, and a second upper hole 54b is formed at a position corresponding to the first upper hole 54a of the first plate 50a. The diameters of the first lower hole 52a and the second lower hole 52b are substantially equal. The diameters of the first upper hole 54a and the second upper hole 54b are substantially equal.

[0066] In the plate bundle 40, the peripheral edge of each first plate 50a is welded to the peripheral edge of the second plate 50b adjacent to the back side of the first plate 50a. Furthermore, in the plate bundle 40, the first lower hole 52a of each first plate 50a overlaps with the second lower hole 52b of the second plate 50b adjacent to the front side of the first plate 50a, and the edges of the overlapping first and second lower holes 52a, 52b are welded together along their entire circumference. Furthermore, in the plate bundle 40, the first upper hole 54a of each first plate 50a overlaps with the second upper hole 54b of the second plate 50b adjacent to the front side of the first plate 50a, and the edges of the overlapping first and second upper holes 54a, 54b are welded together along their entire circumference.

[0067] In the plate bundle 40, the lower convex portion 51a and first lower hole 52a of each first plate 50a, and the lower concave portion 51b and second lower hole 52b of each second plate 50b form a heat medium outlet path 44. Furthermore, in the plate bundle 40, the upper convex portion 53a and first upper hole 54a of each first plate 50a, and the upper concave portion 53b and second upper hole 54b of each second plate 50b form a heat medium inlet path 43.

[0068] The heat medium introduction path 43 and the heat medium outlet path 44 are paths extending along the stacking direction of the heat transfer plates 50a, 50b in the plate bundle 40. Both the heat medium introduction path 43 and the heat medium outlet path 44 are paths disconnected from the internal space 21 of the housing 20.

[0069] The heat medium introduction path 43 communicates with all the heat medium flow paths 42 and is connected to the heat medium inlet 23 . The heat medium outlet path 44 communicates with all the heat medium flow paths 42 and is connected to the heat medium outlet 24 .

[0070] (2-4) Refrigerant flow path and heat medium flow path

[0071] In the plate bundle 40, a plurality of refrigerant flow paths 41 and a plurality of heat medium flow paths 42 are formed adjacent to each other with heat transfer plates 50a and 50b sandwiched therebetween. The refrigerant flow paths 41 and the heat medium flow paths 42 are separated from each other by the heat transfer plates 50a and 50b. A first concave-convex pattern 62a and a second concave-convex pattern 62b are formed on the first plate 50a and the second plate 50b, respectively. The first concave-convex pattern 62a and the second concave-convex pattern 62b are formed by repeatedly forming narrow ridge-like concave-convex patterns. Figure 5 and Figure 6As shown, the first concave-convex pattern 62a and the second concave-convex pattern 62b extend with their ridgelines at a first angle α1 and a second angle α2 relative to the horizontal direction X. The first angle α1 and the second angle α2 are complementary angles. For example, when the first angle α1 is 45 degrees, the second angle α2 is 135 degrees. The first angle α1 is between 15 and 75 degrees. The second angle α2 is between 165 and 105 degrees.

[0072] The refrigerant flow path 41 is a flow path sandwiched between the front surface of the first plate 50a and the back surface of the second plate 50b. The refrigerant flow path 41 is a flow path that communicates with the interior space 21 of the housing 20 and through which the refrigerant flows. The heat medium flow path 42 is a flow path sandwiched between the back surface of the first plate 50a and the front surface of the second plate 50b. The heat medium flow path 42 is disconnected from the interior space of the housing 20.

[0073] (2-4) Guide

[0074] like Figure 5 and Figure 6 As shown in FIG. 4 , a guide portion 70 is provided in the heat medium flow path 42. The guide portion 70 is formed of a first linear flat portion 65a and a second linear flat portion 65b.

[0075] The first linear flat portion 65a is formed linearly on the back surface of the first plate 50a. The first linear flat portion 65a bulges toward the back surface of the first plate 50a, with the bulged top portion being a flat top portion. The first linear flat portion 65a extends linearly along the width direction of the heat transfer plates 50a and 50b.

[0076] The second linear flat portion 65b is formed in a linear shape on the surface of the second plate 50b. The second linear flat portion 65b bulges toward the surface of the second plate 50b, with the top of the bulge forming a flat top. The second linear flat portion 65b extends linearly along the width of the heat transfer plates 50a, 50b. The second linear flat portion 65b is formed at a position corresponding to the first linear flat portion 65a when the first and second plates 50a, 50b overlap. The guide portion 70 is arranged bilaterally symmetrically with respect to the centerline Y of the heat transfer plates 50a, 50b.

[0077] (3) Flow of heat medium and refrigerant

[0078] Refer to the following Figure 7 and Figure 8 The flow of the heat medium and the refrigerant in the heat exchanger 10 will be described in detail. Figure 7 The arrows shown in indicate the flow direction of the heat medium. Figure 8 The state in which liquid refrigerant is stored in the shell is shown. The solid arrows indicate the flow direction of the heat medium, and the dotted arrows indicate the flow direction of the refrigerant.

[0079] like Figure 7 As shown, the heat medium flows from the heat medium inlet 23 into the heat medium introduction path 43. After flowing through the heat medium introduction path 43, the heat medium flows to each heat medium flow path 42. The heat medium flows downward between both side ends of the heat transfer plates 50a and 50b.

[0080] like Figure 8 As shown, the heat medium flowing into the heat medium flow path 42 is guided by the guide portion 70 toward the sides of the heat transfer plates 50a and 50b. Strictly speaking, due to the presence of the guide portion 70, the heat medium flowing in the heat medium flow path 42 cannot move downward and instead flows toward the sides of the heat transfer plates 50a and 50b. The heat medium guided by the guide portion 70 and flowing toward the sides of the heat transfer plates 50a and 50b flows downward from the heat transfer plates 50a and 50b. This heat medium then flows into the heat medium outlet path 44.

[0081] The following describes the flow of refrigerant. After passing through the expansion valve in the refrigerant circuit, the refrigerant flows into the heat exchanger 10. This liquid refrigerant flows from the refrigerant inlet 32 into the internal space 21 of the shell 20. Within the internal space 21, the liquid refrigerant accumulates near the upper end of the plate bundle 40. The plate bundle 40 is immersed in the liquid refrigerant. The refrigerant stored in the internal space 21 has a relatively low pressure. This low-pressure refrigerant exchanges heat with the heat medium flowing in the heat medium flow path 42. Strictly speaking, because the refrigerant flow paths 41 and 42 are adjacent to each other with the heat transfer plates 50a and 50b sandwiched between them, when heat medium flows in the heat medium flow path 42, the liquid refrigerant absorbs heat from the heat medium and evaporates. The evaporated refrigerant moves from the refrigerant flow path 41 to the upper space 21a, located above the internal space 21. The refrigerant in the upper space 21a flows out of the refrigerant circuit through the refrigerant outlet 33.

[0082] (4) Refrigerant and refrigeration cycle

[0083] The refrigeration device R disclosed herein uses a so-called low-pressure refrigerant as its refrigerant. Specifically, the refrigerant used in the refrigeration device R is a refrigerant whose evaporation pressure is lower than atmospheric pressure at temperatures above 0°C. In this example, R-1233zd (1-chloro-3,3,3-trifluoropropene) is used as this refrigerant. R-1233zd has a low GWP (global warming potential), thus providing an environmentally friendly refrigeration device R.

[0084] In the refrigeration device R, other refrigerants include, for example, R1233zd(E) (trans-1-chloro-3,3,3-trifluoropropene), R1224yd(z) (1-chloro-2,3,3,3-tetrafluoropropene), and R-1336mzz(Z) (1,1,1,4,4,4-hexafluoro-2-butene).

[0085] The refrigeration unit R is configured to operate a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than atmospheric pressure in the heat exchanger 10 functioning as an evaporator. During rated operation, the refrigeration unit R operates a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than atmospheric pressure. More strictly speaking, during rated operation, the refrigeration unit R operates a refrigeration cycle in which the evaporation pressure of the refrigerant at a temperature of 0°C or higher is lower than atmospheric pressure.

[0086] (5) Dimensional relationship of heat transfer plates

[0087] like Figure 9 As shown, in the plate bundle 40, the dimensional relationship between the plurality of heat transfer plates 50a, 50b is set as follows. Figure 9 The left side in the figure is set as the front side of the plate bundle 40. Figure 9 The right side in FIG is defined as the rear side of the plate bundle 40. In the plate bundle 40, the stacking direction of the heat transfer plates 50a and 50b corresponds to the front-rear direction.

[0088] The plurality of heat transfer plates 50a, 50b are arranged in the front-to-back direction. The first plate 50a and the second plate 50b are arranged alternately. Figure 9 As shown, the frontmost position on the back of the second plate 50b is designated as a, and the rearmost position on the back of the second plate 50b is designated as b. The frontmost position on the surface of the first plate 50a corresponds to position b. The rearmost position on the surface of the first plate 50a is designated as c. The distance from position a to position b on the second plate 50b is designated as P1, and the distance from position b to position c on the first plate 50a is designated as P2. In this case, P1 corresponds to the length (flow path height) of the first flow path 41a formed on the back side of the second plate 50b in the refrigerant flow path 41 in the front-to-back direction. P2 corresponds to the length (flow path height) of the second flow path 41b formed on the surface side of the first plate 50a in the refrigerant flow path 41 in the front-to-back direction. In the plate bundle 40 of this example, P1 is equal to P2.

[0089] The pitch P between adjacent heat transfer plates 50a and 50b is the distance between center lines m1 and m2. It is the distance between center line m1 of the first flow path 41a on the back side of the first plate 50a, which is the height of the flow path, and center line m2 of the second plate 50b, which is the height of the flow path P2. Here, center line m1 is a line segment passing through the middle of the first flow path 41a in the front-to-back direction and perpendicular to the front-to-back direction. Center line m2 is a line segment passing through the middle of the second flow path 41b in the front-to-back direction and perpendicular to the front-to-back direction. In the plate bundle 40 of this example, pitch P is equal to P1 and P2.

[0090] In the heat exchanger 10 of this embodiment, the pitch P is set to improve the heat exchange performance of the plate bundle 40. The pitch P is preferably greater than 1.2 mm, more preferably greater than 1.5 mm. The pitch P is preferably less than 2.1 mm, more preferably less than 1.8 mm.

[0091] In other words, P1 and P2 are preferably larger than 1.2 mm, more preferably greater than 1.5 mm, and preferably less than 2.1 mm, more preferably less than 1.8 mm.

[0092] (6) Performance evaluation of heat exchanger

[0093] Figure 10 The results of an evaluation of the relationship between the pitch P of the heat transfer plates 50a, 50b and the heat exchange performance are shown. In this evaluation, the pitch P of the heat transfer plates 50a, 50b was changed to 1.2mm, 1.5mm, 1.8mm, and 2.1mm, and the heat flux and heat transfer coefficient of the heat transfer plates 50a, 50b were calculated when R-1233zd flowed in the refrigerant flow path 41. Figure 10 In the graph, the heat flux is set as the horizontal axis and the heat transfer coefficient is set as the vertical axis.

[0094] Depend on Figure 10 It is clear that when the pitch P is set to 1.2 mm, the heat transfer coefficient tends to be lower than that of other pitches. In particular, the heat transfer coefficient is lower in the range where the heat flux is relatively large.

[0095] In the refrigerant flow path 41, bubbles form as the refrigerant vaporizes. If the refrigerant is a so-called low-pressure refrigerant such as R-1233zd, the volume of the bubbles tends to increase. If the spacing P is too small, the bubbles tend to diffuse along the heat transfer plates 50a and 50b, reducing the contact area between the liquid refrigerant and the plates 50a and 50b and reducing the heat transfer coefficient. By contrast, a spacing greater than 1.2 mm makes it difficult for bubbles to diffuse along the plates 50a and 50b, thereby minimizing the reduction in heat transfer coefficient caused by the formation of bubbles.

[0096] In particular, by Figure 10 It can also be seen that setting the pitch P to 1.5 mm or greater increases the heat transfer coefficient over a wider range of heat flux. On the other hand, when the pitch P is set to 2.1 mm, the heat transfer coefficient decreases compared to when the pitch P is set to 1.8 mm. It can be speculated that this is because the excessively wide pitch P reduces the flow velocity of the refrigerant flowing through the refrigerant flow path 41.

[0097] As can be seen from the above evaluation results, the pitch P is preferably larger than 1.2 mm, more preferably not less than 1.5 mm, and even more preferably not less than 1.5 mm and not more than 2.1 mm.

[0098] (7) Characteristics

[0099] (7-1)

[0100] A heat exchanger 10 is installed in a refrigeration unit R and functions as an evaporator. The refrigeration unit R is configured to perform a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than atmospheric pressure. The heat exchanger 10 includes a housing 20 and a plate bundle 40. The housing 20 defines an interior space 21. The plate bundle 40 is arranged within the interior space 21 and includes a plurality of heat transfer plates 50a and 50b.

[0101] In refrigeration device R, if a refrigeration cycle is performed in which the refrigerant's evaporation pressure is lower than atmospheric pressure, the volume of the vaporized refrigerant increases in the evaporator, or heat exchanger 10, and heat exchange performance tends to decrease. However, because heat exchanger 10 comprises a plate bundle 40 formed by stacking multiple heat transfer plates 50a, 50b, the performance of heat exchanger 10 can be maintained while minimizing the size of heat exchanger 10.

[0102] (7-2)

[0103] The heat exchanger 10 is provided in a refrigeration system R configured to perform a refrigeration cycle in which the evaporation pressure of a refrigerant at a temperature of 0° C. or higher is lower than atmospheric pressure. Specifically, the heat exchanger 10 is provided in a refrigeration system R using 1-chloro-3,3,3-trifluoropropene as a refrigerant.

[0104] In the refrigeration apparatus R using the so-called low-pressure refrigerant as described above, it is also possible to suppress an increase in the size of the heat exchanger 10 while ensuring the performance of the heat exchanger 10 .

[0105] (7-3)

[0106] By making the pitch P of the plurality of heat transfer plates 50a, 50b larger than 1.2 mm, it is possible to suppress the performance degradation of the heat exchanger 10 due to the generation of bubbles. In particular, by making the pitch P larger than 1.5 mm, Figure 10 It is also clear that the performance of the heat exchanger 10 can be improved. Furthermore, by setting the pitch P to 1.8 mm or less, it is possible to suppress a decrease in the performance of the heat exchanger 10 due to a decrease in the flow velocity of the refrigerant in the refrigerant flow path 41 .

[0107] (8) Modification

[0108] The above-described embodiment may also adopt the following modified configurations.

[0109] (8-1) Modification 1

[0110] like Figure 11As shown, roughened portions 80 are formed on the surfaces of the plurality of heat transfer plates 50a and 50b. The roughened portions 80 are formed at locations on the plurality of heat transfer plates 50a and 50b that face the refrigerant flow path 41. The roughened portions 80 are formed by sandblasting a predetermined medium onto the surfaces of the heat transfer plates 50a and 50b.

[0111] If the surfaces of the heat transfer plates 50a and 50b are roughened by the roughened portion 80, the wettability of the liquid refrigerant on the surfaces of the heat transfer plates 50a and 50b is improved, thereby improving the performance of the heat exchanger 10.

[0112] (8-2) Modification 2

[0113] The heat exchanger 10 of the embodiment may also be a falling film plate and shell heat exchanger. Strictly speaking, the heat exchanger 10 may include a sprayer above the plate bundle 40 in the shell 20 for spraying liquid refrigerant toward the plate bundle 40. Furthermore, the heat exchanger 10 may include a plate bundle having a structure for spraying liquid refrigerant.

[0114] While the above describes the embodiments and variations, it should be understood that various modifications may be made to the embodiments and details without departing from the spirit and scope of the claims. Elements of the above embodiments, variations, and other embodiments may also be appropriately combined or substituted. The terms "first," "second," "third," and so on, described above, are used solely to distinguish between sentences containing these terms and do not limit the number or order of the sentences.

[0115] Industrial Applicability

[0116] In summary, the present disclosure is very useful for heat exchangers and refrigeration devices.

[0117] - Explanation of symbols -

[0118] 5. Evaporator

[0119] 10. Heat exchanger

[0120] 20 housing

[0121] 21 Interior Space

[0122] 40 plate bundle

[0123] 50a, 50b heat transfer plates

[0124] R Refrigeration Unit

Claims

1. A heat exchanger provided in a refrigeration device (R) and functioning as an evaporator, wherein the refrigeration device (R) is configured to perform a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than atmospheric pressure, characterized in that: The heat exchanger comprises a shell (20) and a plate bundle (40), The housing (20) forms an inner space (21), The plate bundle (40) is arranged in the inner space (21) and includes a plurality of heat transfer plates (50a, 50b), The plurality of heat transfer plates (50a, 50b) include first plates (50a) and second plates (50b) alternately arranged in a front-to-rear direction. Concave-convex patterns (62a, 62b) are formed on the first plate (50a) and the second plate (50b), respectively. A flow path sandwiched between the surface of the first plate (50a) and the back surface of the second plate (50b) constitutes a refrigerant flow path (41), and a refrigerant flows in the refrigerant flow path (41). A flow path sandwiched between the back surface of the first plate (50a) and the surface of the second plate (50b) constitutes a heat medium flow path (42), and a heat medium that exchanges heat with the refrigerant in the refrigerant flow path (41) flows in the heat medium flow path (42). The refrigerant flow path (41) is composed of a first flow path (41a) on the back side of the second plate (50b) and a second flow path (41b) on the front side of the first plate (50a). A spacing P between a center line m1 of the first flow path (41a) in the front-rear direction and a center line m2 of the second flow path (41b) in the front-rear direction is greater than or equal to 1.5 mm and less than or equal to 2.1 mm.

2. The heat exchanger according to claim 1, characterized in that: The heat exchanger is provided in a refrigeration device (R) configured to be capable of performing a refrigeration cycle in which the evaporation pressure of the refrigerant at a temperature of 0° C. or higher is lower than atmospheric pressure.

3. The heat exchanger according to claim 2, characterized in that: The heat exchanger is provided in a refrigeration device (R) using 1-chloro-3,3,3-trifluoropropene as the refrigerant.

4. The heat exchanger according to any one of claims 1 to 3, characterized in that: A roughened portion (80) is formed on the surface of the heat transfer plates (50a, 50b).

5. A refrigeration device, characterized in that: The refrigeration device comprises the heat exchanger (10) according to any one of claims 1 to 3, The refrigeration device is configured to perform a refrigeration cycle in which the evaporation pressure of the refrigerant is lower than atmospheric pressure.

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