Heat exchanger

Abstract

[Problem] To provide a heat exchanger in which a deviation in the flow of a refrigerant in a flow path is suppressed. [Solution] This heat exchanger is a heat exchanger in which a plurality of metal plates are laminated. At least one of the plurality of metal plates has an inflow port, an outflow port, a partition wall, and a plurality of projections protruding from the partition wall. A flow path part is formed on the partition wall by the plurality of projections. The flow path part has a first flow path part, a second flow path part, and a third flow path part between the inflow port and the outflow port. The first flow path part, the second flow path part, and the third flow path part are arranged in this order from the inflow port toward the outflow port. The flow path resistance of the second flow path part is greater than the flow path resistance of each of the first flow path part and the third flow path part.

Description

heat exchanger

[0001] The present invention relates to a stacked heat exchanger.

[0002] A heat exchanger has been proposed in which a plurality of columnar protrusions are provided on each of one and the other surfaces of a metal plate, thereby forming flow paths on each of the two surfaces of the metal plate (see, for example, Patent Document 1). In this heat exchanger, the flow path formed on one surface of the metal plate functions as a high-temperature flow path, and the flow path formed on the other surface of the metal plate functions as a low-temperature flow path. In this heat exchanger, the width of the inlet and the width of the outlet are the same as the width of the flow paths.

[0003] JP 2018-096581 A

[0004] In the heat exchanger described above, the protrusions on both sides of the metal plate are uniformly spaced apart, and even if the width of the inlet is the same as the width of the flow path, the refrigerant is likely to become unevenly distributed within the flow path, potentially resulting in a dead zone where the refrigerant does not circulate sufficiently within the flow path.

[0005] In view of the above circumstances, an object of the present invention is to provide a heat exchanger in which the uneven flow of refrigerant within a flow path is suppressed.

[0006] To achieve the above object, a heat exchanger according to one aspect of the present invention is a heat exchanger including a plurality of stacked metal plates. At least one of the plurality of metal plates has an inlet, an outlet, a partition wall, and a plurality of protrusions protruding from the partition wall. The plurality of protrusions form a flow path portion on the partition wall. The flow path portion has a first flow path portion, a second flow path portion, and a third flow path portion between the inlet and the outlet. The first flow path portion, the second flow path portion, and the third flow path portion are arranged in this order from the inlet to the outlet. The flow path resistance of the second flow path portion is greater than the flow path resistances of the first flow path portion and the third flow path portion.

[0007] With such a heat exchanger, unevenness in the flow of the refrigerant within the flow passages can be suppressed.

[0008] In the heat exchanger, the second flow path portion may have a smaller flow path cross-sectional area than each of the first flow path portion and the third flow path portion.

[0009] With such a heat exchanger, the deviation of the flow of the refrigerant in the flow passages can be further reduced.

[0010] In the heat exchanger, the area per unit area occupied by the protrusions in the second flow path section may be higher than the area per unit area occupied by the protrusions in the first flow path section and the third flow path section.

[0011] With such a heat exchanger, the deviation of the flow of the refrigerant in the flow passages can be further reduced.

[0012] In the heat exchanger, the second flow path portion may be disposed closer to the inlet than the outlet.

[0013] With such a heat exchanger, the deviation of the flow of the refrigerant in the flow passages can be further reduced.

[0014] In the heat exchanger, the second flow path portion may be disposed closer to the outlet than the inlet.

[0015] With such a heat exchanger, the deviation of the flow of the refrigerant in the flow passages can be further reduced.

[0016] As described above, according to the present invention, a heat exchanger is provided in which the uneven flow of the refrigerant in the flow passage is suppressed.

[0017] [Correction based on Rule 91, 28.08.2024] A schematic perspective view showing a heat exchanger of this embodiment. A schematic perspective view when a portion of the heat exchanger is removed. A schematic perspective view when a portion of the heat exchanger is removed. Figure (a) is a schematic plan view of at least one metal plate 22 out of the multiple metal plates 22 forming the laminate 20. Figure (b) is a schematic cross-sectional view taken along line B1-B2 in Figure (a). Figure (a) is a schematic plan view of at least one metal plate 22 out of the multiple metal plates 21 forming the laminate 20. Figure (b) is a schematic cross-sectional view taken along line A11-A12 in Figure (a). Figure (c) is a schematic cross-sectional view taken along line A21-A22 in Figure (a). Figure (d) is a schematic cross-sectional view taken along line A31-A32 in Figure (a). A schematic plan view showing the function of a metal plate according to a reference example. A schematic plan view explaining an example of the function of this embodiment. FIG. 1A is a schematic plan view of a first modified example of the present embodiment, and FIG. 1B is a schematic plan view of a second modified example of the present embodiment. FIG. 1A is a schematic plan view of a third modified example of the present embodiment, and FIG. 1B is a schematic plan view of a fourth modified example of the present embodiment. FIG. 10 is a schematic plan view of a fifth modified example of the present embodiment. FIG. 11 is a schematic plan view of a sixth modified example of the present embodiment.

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. X, Y, and Z axis coordinates may be used in each drawing. In addition, the same reference numerals may be used to designate identical components or components having the same functions, and after describing the components, the description may be omitted as appropriate.

[0019] (Heat Exchanger) FIG. 1 is a schematic perspective view showing a heat exchanger of this embodiment.

[0020] The heat exchanger 1 is a heat exchanger in which multiple metal plates are stacked. The heat exchanger 1 has a main surface (front surface) 1u, a main surface (back surface) 1d opposite the main surface 1u, and a side surface 1w connected to the main surface 1u and the main surface 1d. The heat exchanger 1 is applied, for example, to a stacked-type microchannel heat exchanger. The heat exchanger 1 includes a heat exchanger main body 2. The heat exchanger main body 2 is provided with an inlet pipe 5, an outlet pipe 6, an outlet pipe 7, and an inlet pipe 8. A line connecting the inlet pipe 5 and the outlet pipe 6 intersects with a line connecting the inlet pipe 8 and the outlet pipe 7. In this embodiment, the stacking direction of the multiple metal plates in the heat exchanger 1 is the Z-axis direction, the direction in which the inlet pipe 5 is viewed from the inlet pipe 8 is the X-axis direction, and the direction in which the outlet pipe 6 is viewed from the inlet pipe 8 is the Y-axis direction.

[0021] The heat exchanger body 2 has a stacked body 20, a metal plate (top plate) 3, and a metal plate (bottom plate) 4. The stacked body 20 is sandwiched between the metal plate 3 and the metal plate 4 in the stacking direction of the heat exchanger 1 (the stacking direction of the multiple metal plates). The side surface 1w of the heat exchanger 1 also serves as the side surface of the heat exchanger body 2 and the stacked body 20. The stacked body 20 has a plurality of metal plates (first heat transfer plates) 21 and a plurality of metal plates (second heat transfer plates) 22. The metal plate 3, the multiple metal plates 21, the multiple metal plates 22, and the metal plate 4 are each formed in a plate shape. In the stacked body 20, the multiple metal plates 21 and the multiple metal plates 22 are stacked alternately. The metal plates 3 and the metal plates 4 are each outer shell plates of the stacked body 20 and do not have flow paths formed therein.

[0022] 1 , the metal plate 4, the plurality of metal plates 21, the plurality of metal plates 22, and the metal plate 3 are each integrally formed by, for example, diffusion bonding, brazing, etc. For example, in the example of FIG. 1 , the metal plate 21 is stacked directly on the metal plate 4, the metal plate 22 is stacked on top of that, and the metal plates 21 and 22 are stacked alternately on top of that, with the metal plate 22 being the topmost layer in the heat exchanger body 2, and the metal plate 3 being stacked on this metal plate 22. Each of the metal plate 3 and the metal plate 4 is not limited to a single metal plate, but may be a metal plate in which a plurality of metal plates are stacked and integrated with the stack body 20 by diffusion bonding, or a metal plate in which a plurality of metal plates are joined in the stacking direction by brazing, etc.

[0023] When the heat exchanger 1 functions as an evaporator, for example, a low-temperature fluid (e.g., a liquid refrigerant or a gas-liquid two-phase refrigerant that undergoes a phase change during heat exchange) flows into the heat exchanger body 2 through the inlet pipe 8. Also, a high-temperature fluid (e.g., water or hot water that does not undergo a phase change during heat exchange, or a liquid refrigerant or a gas-liquid two-phase refrigerant that undergoes a phase change during heat exchange) flows into the heat exchanger body 2 through the inlet pipe 5. The low-temperature fluid exchanges heat with the high-temperature fluid by flowing through the flow path within the heat exchanger body 2, and is heated to increase its dryness, and then flows out of the heat exchanger body 2 through the outlet pipe 7. The high-temperature fluid that has exchanged heat with the low-temperature fluid in the heat exchanger body 2 also decreases in temperature, and flows out of the heat exchanger body 2 through the outlet pipe 6.

[0024] 1, solid lines are drawn to indicate the boundaries between the metal plates stacked in the stacking direction, but the boundaries may disappear after joining, making the solid lines invisible. Also, the stack 20 may be formed from a pair of metal plates 21 and 22.

[0025] Fig. 2 is a schematic perspective view of the heat exchanger with some parts removed. For example, Fig. 2 shows a state in which metal plate 4 (bottom plate) and metal plate 3 (top plate) have been removed from heat exchanger 1. Fig. 2 also shows inflow pipe 5, outflow pipe 6, outflow pipe 7, and inflow pipe 8 have been removed from heat exchanger body 2.

[0026] The stack 20 is formed with an inflow space 15, an outflow space 16, an outflow space 17, and an inflow space 18. The spaces 15, 16, 17, and 18 penetrate the stack 20 in the stacking direction. The spaces 15, 16, 17, and 18 are closed by the metal plates 3 and 4 in the stacking direction of the stack 20.

[0027] An opening 150 communicating with the space 15, an opening 160 communicating with the space 16, an opening 170 communicating with the space 17, and an opening 180 communicating with the space 18 are formed on the side surface 1w of the laminate 20. The opening 150 is formed on the side surface 1w near the space 15. The opening 160 is formed on the side surface 1w near the space 16. The opening 170 is formed on the side surface 1w near the space 17. The opening 180 is formed on the side surface 1w near the space 18.

[0028] The inlet pipe 5 shown in FIG. 1 is inserted into the opening 150 and communicates with the space 15. The inlet pipe 5 is joined to the opening 150 by, for example, brazing. The outlet pipe 6 is inserted into the opening 160 and communicates with the space 16. The outlet pipe 6 is joined to the opening 160 by, for example, brazing. The outlet pipe 7 is inserted into the opening 170 and communicates with the space 17. The outlet pipe 7 is joined to the opening 170 by, for example, brazing. The inlet pipe 8 is inserted into the opening 180 and communicates with the space 18. The inlet pipe 8 is joined to the opening 180 by, for example, brazing.

[0029] For example, a recess 220 recessed toward the main surface 1d is formed on the main surface 1u side of the metal plate 22, and a flow path (described later) is formed in a region 221 indicated by a dot in the recess 220. The flow path (or the recess 220) of the metal plate 22 communicates with the space 15 and the space 16.

[0030] Fig. 3 is a schematic perspective view of the heat exchanger with a portion thereof removed, showing a state in which the uppermost metal plate 22 on the main surface 1u side has been removed from the state shown in Fig. 2 .

[0031] For example, a recess 210 recessed toward the main surface 1d is formed on the main surface 1u side of the metal plate 21, and a flow path (described later) is formed in a region 211 indicated by a dot in the recess 210. The flow path (or the recess 210) of the metal plate 21 communicates with the space 17 and the space 18.

[0032] The metal plate 21 and the metal plate 22 that form the laminate 20 will be described starting with the metal plate 22 .

[0033] Fig. 4(a) is a schematic plan view of at least one metal plate 22 among the plurality of metal plates 22 forming the laminate 20. Fig. 4(b) is a schematic cross-sectional view taken along line B1-B2 in Fig. 4(a).

[0034] The metal plate 22 has a through hole 252 serving as an inlet, a through hole 262 serving as an outlet, a through hole 272, a through hole 282, a partition wall (bottom) 222, an outer periphery (side wall) 223 surrounding the partition wall 222, and a plurality of columnar protrusions 224 provided on the partition wall 222 and protruding from the partition wall 222. The through hole 252, the through hole 262, the through hole 272, and the through hole 282 penetrate the metal plate 22 in the thickness direction. The planar shape of each of the plurality of protrusions 224 is, for example, circular. The plurality of protrusions 224 are arranged, for example, in a staggered pattern. A step is formed between the partition wall 222 and the outer periphery 223, thereby forming a recess 220 in the metal plate 22. The partition wall 222 is the bottom of the recess 220.

[0035] Furthermore, by forming the plurality of protrusions 224 on the partition wall 222, a flow path portion 225 is formed on the partition wall 222. The through holes 252 and 262 communicate with the flow path portion 225 on the partition wall 222. The through holes 272 and 282 do not communicate with the flow path portion 225 on the partition wall 222. For example, when the heat exchanger 1 is used as an evaporator, the high-temperature fluid flows in through the through holes 252, passes through the flow path portion 225 on the partition wall 222, and flows out to the through holes 262. Note that, with regard to the metal plate 22, an example in which the protrusions 224 are not provided on the partition wall 222 is also included in this embodiment.

[0036] Next, the metal plate 21 will be described.

[0037] [Correction based on Rule 91 28.08.2024] Figure 5(a) is a schematic plan view of at least one metal plate 22 of the multiple metal plates 21 forming the laminate 20. Figure 5(b) is a schematic cross-sectional view taken along line A11-A12 in Figure 5(a). Figure 5(c) is a schematic cross-sectional view taken along line A21-A22 in Figure 5(a). Figure 5(d) is a schematic cross-sectional view taken along line A31-A32 in Figure 5(a).

[0038] The metal plate 21 has a through hole 251, a through hole 261, a through hole 271 serving as an outlet, a through hole 281 serving as an inlet, a partition wall (bottom) 212, an outer periphery (side wall) 213 surrounding the partition wall 212, and a plurality of columnar protrusions 214 provided on the partition wall 212 and protruding from the partition wall 212. The plurality of protrusions 214 include a plurality of protrusions 2141 (first protrusions), a plurality of protrusions 2142 (second protrusions), and a plurality of protrusions 2143 (third protrusions). The through hole 251, the through hole 261, the through hole 271, and the through hole 281 penetrate the metal plate 21 in the thickness direction. The planar shape of each of the plurality of protrusions 214 is, for example, circular. A step is formed by the partition wall 212 and the outer periphery 213, thereby forming a recess 210 in the metal plate 21. The partition wall 212 is the bottom of the recess 210 .

[0039] Furthermore, a flow path portion 215 is formed on the partition wall 212 by forming the plurality of protrusions 214 on the partition wall 212. The through-hole 271 and the through-hole 281 communicate with the flow path portion 215 on the partition wall 212. The through-hole 251 and the through-hole 261 do not communicate with the flow path portion 215 on the partition wall 212. For example, when the heat exchanger 1 is used as an evaporator, the low-temperature fluid flows in through the through-hole 281, passes through the flow path portion 215 on the partition wall 212, and flows out to the through-hole 271.

[0040] The flow path portion 215 has a first flow path portion 2151, a second flow path portion 2152, and a third flow path portion 2153 between the through hole (inlet) 281 and the through hole (outlet) 271. In the flow path portion 215, the first flow path portion 2151, the second flow path portion 2152, and the third flow path portion 2153 are arranged in this order from the through hole 281 toward the through hole 271. Between the through hole 281 and the through hole 271, the second flow path portion 2152 is sandwiched between the first flow path portion 2151 and the third flow path portion 2153.

[0041] In the first flow path section 2151, the multiple protrusions 2141 are arranged, for example, in a staggered pattern. In the second flow path section 2152, the multiple protrusions 2142 are arranged, for example, in a linear pattern in a direction (Y-axis direction) perpendicular to the direction from the first flow path section 215 to the third flow path section 2153. In the third flow path section 2153, the multiple protrusions 2143 are arranged, for example, in a staggered pattern.

[0042] In the metal plate 21, when the metal plate 21 is viewed from above, the area of ​​the protrusions 2142 is smaller than the area of ​​the protrusions 2141 and the area of ​​the protrusions 2143. Furthermore, in the second flow path portion 2152, the protrusions 2142 are arranged more densely than the protrusions 2141 included in the first flow path portion 2151 and the protrusions 2143 included in the third flow path portion 2153.

[0043] That is, in the second flow path section 2152, the area occupied by the protrusions 2142 per unit area of ​​the second flow path section 2152 (the area occupied by the multiple protrusions 2142 included in the second flow path section 2152 per unit area of ​​the metal plate 21) is larger than the area occupied by the protrusions 2141 per unit area of ​​the first flow path section 2151 (the area occupied by the multiple protrusions 2141 included in the first flow path section 2151 per unit area of ​​the metal plate 21) in the first flow path section, and is larger than the area occupied by the protrusions 2143 per unit area of ​​the third flow path section 2153 (the area occupied by the multiple protrusions 2143 included in the third flow path section 2153 per unit area of ​​the metal plate 21).

[0044] As a result, in the metal plate 21, the flow path cross-sectional area of ​​the second flow path portion 2152 (the cross-sectional area perpendicular to the direction in which the fluid flows in the flow path of the second flow path portion 2152) is smaller than the flow path cross-sectional area of ​​the first flow path portion 2151 (the cross-sectional area perpendicular to the direction in which the fluid flows in the flow path of the second flow path portion 2151) and the flow path cross-sectional area of ​​the third flow path portion 2153 (the cross-sectional area perpendicular to the direction in which the fluid flows in the flow path of the third flow path portion 2153). That is, the flow path resistance of the second flow path portion 2152 is greater than the flow path resistance of the first flow path portion 2151 and the flow path resistance of the third flow path portion 2153. That is, in a flow path portion having a large number of protrusions or a large cross-sectional area of ​​the protrusions, the area of ​​the protrusions per unit area increases, and the flow path resistance increases. Note that flow path resistance refers to a force that obstructs the flow of a fluid received from a flow path when the fluid flows through a flow path of a heat exchanger, etc.

[0045] In the laminate 20, when a plurality of metal plates 21 and a plurality of metal plates 22 are alternately stacked, the through holes 251 and 252 are connected in the stacking direction to form space 15. The through holes 261 and 262 are connected in the stacking direction to form space 16. The through holes 271 and 272 are connected in the stacking direction to form space 17. The through holes 281 and 282 are connected in the stacking direction to form space 18.

[0046] (Operation) The operation of the heat exchanger 1 when used as an evaporator will be described. In this case, a low-temperature fluid flows into the flow path 215 of the metal plate 21 from the through-holes (inlet) 281. This low-temperature fluid is a liquid refrigerant or a gas-liquid two-phase refrigerant (a refrigerant having a higher proportion of liquid components than gas components) with a low dryness fraction, and exchanges heat with the high-temperature fluid flowing through the flow path 225 of the metal plate 22, increasing the dryness fraction, and then flows out of the metal plate 21 through the through-holes (outlet) 271.

[0047] When liquid refrigerant or two-phase gas-liquid refrigerant flows through a flow path in a metal plate, the liquid refrigerant or two-phase gas-liquid refrigerant has a larger inertia than gas refrigerant, making it difficult for it to flow evenly within the flow path. This can result in a phenomenon in which the liquid refrigerant or two-phase gas-liquid refrigerant does not distribute evenly throughout the flow path (the formation of a dead water zone). Furthermore, gas refrigerant has a smaller inertia than liquid refrigerant or two-phase gas-liquid refrigerant. Therefore, the gas refrigerant tends to spread within the flow path. In such a case, the gas refrigerant tends to be biased to both sides of the flow path, and the liquid refrigerant or two-phase gas-liquid refrigerant is carried by the gas refrigerant flux and reaches the outlet, making it even more difficult for the liquid refrigerant or two-phase gas-liquid refrigerant to spread within the flow path.

[0048] For example, Fig. 6 is a schematic plan view showing the function of a metal plate according to a reference example. In the metal plate 100 shown in Fig. 6, a plurality of protrusions 2145 having the same planar shape are arranged in a staggered pattern at equal intervals.

[0049] In such a case, the liquid refrigerant or gas-liquid two-phase refrigerant that flows in through the through-hole (inlet) 281 is likely to become biased in a direction perpendicular to the refrigerant flow direction as it flows through the flow path of the metal plate 100 toward the through-hole (outlet) 271. For example, if an imaginary line 101 is drawn from the through-hole (inlet) 281 to the through-hole (outlet) 271, the liquid refrigerant or gas-liquid two-phase refrigerant may become biased near the imaginary line 101, and the proportion of gas refrigerant may increase the further away from the imaginary line 101. For example, in FIG. 6 , the region where the liquid refrigerant is more abundant than the gas refrigerant is indicated by dotted region 100L. Furthermore, a dead water region where the liquid refrigerant does not reach the flow path of the metal plate 100 is indicated by dashed line as region 100d.

[0050] That is, when liquid refrigerant or two-phase gas-liquid refrigerant flows through the through-hole (inlet) 281 and flows toward the through-hole (outlet) 271, the inertia of the liquid refrigerant or two-phase gas-liquid refrigerant is greater than that of the gas refrigerant. Furthermore, the gas refrigerant flows faster, and the liquid refrigerant is carried along by the gas refrigerant's flow, increasing the tendency for the liquid refrigerant to flow in a straight line. As a result, the liquid refrigerant is less likely to spread in a direction perpendicular to the imaginary line 101. This phenomenon is particularly pronounced when the through-hole (inlet) 281 and the through-hole (outlet) 271 are narrow and located near the corner of the recess 210. If a dead water region is formed in the flow path, the portion of the heat exchanger 215 that functions as an evaporator for evaporating the liquid refrigerant or two-phase gas-liquid refrigerant is reduced, resulting in a decrease in heat exchange capacity. Therefore, it is preferable to prevent the formation of dead water regions and ensure that the liquid refrigerant or two-phase gas-liquid refrigerant is evenly distributed throughout the flow path.

[0051] The operation of this embodiment will be described below. Fig. 7 is a schematic plan view illustrating an example of the operation of this embodiment. Fig. 7 shows a schematic plan view of the metal plate 21.

[0052] In the metal plate 21, the flow path portion 215 has a first flow path portion 2151, a second flow path portion 2152, and a third flow path portion 2153. The flow path resistance of the second flow path portion 2152 is greater than the flow path resistance of the first flow path portion 2151 and the flow path resistance of the third flow path portion 2153.

[0053] As a result, the flow of the liquid refrigerant or the two-phase gas-liquid refrigerant that flows in through the through hole 281 is impeded by the second flow path portion 2152, and the region between the through hole 281 and the second flow path portion 2152, i.e., the first flow path portion 2151, approaches a state where the liquid refrigerant or the two-phase gas-liquid refrigerant is filled. That is, the liquid refrigerant or the two-phase gas-liquid refrigerant tends to spread in the direction perpendicular to the virtual line 101 in the first flow path portion 2151. Furthermore, after being rectified by the second flow path portion 2152, the liquid refrigerant or the two-phase gas-liquid refrigerant passes through the third flow path portion 2153 while maintaining a spread state in the direction perpendicular to the virtual line 101, and flows out of the metal plate 21 from the through hole 271 (the region 21L indicated by dots).

[0054] In this way, by using the heat exchanger 1, the area between the through hole 281 and the second flow path section 2152 becomes more likely to be filled with liquid refrigerant or two-phase gas-liquid refrigerant, and the liquid refrigerant or two-phase gas-liquid refrigerant spreads throughout the entire flow path.

[0055] Furthermore, when the heat exchanger 1 is used, the second flow path portion 2152 rectifies the flow of the refrigerant flowing in from the inlet 281, eliminating the need for a flow dividing portion (header portion) that divides the refrigerant flowing in from the inlet before it reaches the flow path. This allows the entire recess 210 to function as a heat exchanger, making it possible to reduce the size of the heat exchanger. Furthermore, the provision of a flow dividing portion reduces pressure loss of the low-temperature refrigerant. Furthermore, the multiple protrusions 2142 are densely arranged in the center of the metal plate 21, improving the strength of the center portion where the dynamic pressure of the fluid in the flow path is relatively high, thereby suppressing deformation of the metal plate 21.

[0056] In the metal plate 22, a high-temperature fluid, such as water or hot water, flows in through the through-holes (inlet) 252. The high-temperature fluid that flows in through the through-holes 252 exchanges heat with the low-temperature fluid flowing within the metal plate 21, lowering its temperature and then flowing out of the metal plate 22 through the through-holes (outlet) 262. In the metal plate 22, the high-temperature fluid flowing through the flow path 225 is water or hot water, which does not undergo a phase change during heat exchange, or a gas refrigerant, which undergoes a phase change during heat exchange. Here, since the heat exchanger 1 functions as an evaporator for low-temperature fluid, if the high-temperature fluid is a refrigerant that undergoes a phase change, the high-temperature fluid flows in as a single-phase gas through the inlet. Therefore, even if the flow path resistance of the flow path 225 is uniform, as in the flow path 225 shown in FIG. 4( a), the liquid refrigerant will be distributed evenly throughout the flow path 225. Note that this embodiment also includes an example in which the flow path of the metal plate 21 is used instead of the flow path of the metal plate 22.

[0057] (Modifications) The second flow path portion 2152 of the metal plate 21 is not limited to the structure shown in Fig. 5(a). For example, Fig. 8(a) is a schematic plan view according to Modification 1 of this embodiment, Fig. 8(b) is a schematic plan view according to Modification 2 of this embodiment, Fig. 9(a) is a schematic plan view according to Modification 3 of this embodiment, and Fig. 9(b) is a schematic plan view according to Modification 4 of this embodiment. Fig. 10 is a schematic plan view according to Modification 5 of this embodiment, and Fig. 11 is a schematic plan view according to Modification 6 of this embodiment.

[0058] For example, in Modification 1 shown in FIG. 8( a), a plurality of protrusions 2142a having a circular planar shape are linearly arranged in the second flow path portion 2152. Here, the area of ​​the protrusions 2142a when the metal plate 21 is viewed from above is larger than the area of ​​the protrusions 2141 and 2143. By making the area of ​​the protrusions 2142a larger than the area of ​​the protrusions 2141 and 2143, the gap between adjacent protrusions 2142a is narrowed. As a result, the flow path resistance of the second flow path portion 2152 is larger than the flow path resistance of the first flow path portion 2151 and the flow path resistance of the third flow path portion 2153. Such a structure is also included in this embodiment.

[0059] 8(b), a plurality of projections 2142b having a diamond-shaped planar shape may be arranged in the second flow path portion 2152, and a plurality of projections 2142c having a rectangular planar shape may be arranged in the second flow path portion 2152, as in Modification 2 shown in Fig. 9(a), a structure such as this also makes the flow path resistance of the second flow path portion 2152 greater than the flow path resistance of the first flow path portion 2151 and the flow path resistance of the third flow path portion 2153.

[0060] 9(b), a plurality of protrusions 2142d having an S-shaped planar shape may be arranged in the second flow path portion 2152. By arranging a plurality of S-shaped protrusions 2142d in the second flow path portion 2152, the second flow path portion 2152 becomes highly resistant to the low-temperature fluid, and the liquid refrigerant or the liquid refrigerant in the gas-liquid two-phase refrigerant tends to fill the second flow path portion 2152 before the second flow path portion 2152. Such a structure is also included in the present embodiment.

[0061] 10 , in the metal plate 21, the second flow path portion 2152 is disposed closer to the through hole (inlet) 281 than the through hole (outlet) 271. This makes the area of ​​the third flow path portion 2153 larger than the area of ​​the first flow path portion 2151. Furthermore, for the low-temperature fluid flowing in from the through hole 281, the distance it flows through the third flow path portion 2153 is longer than the distance it flows through the first flow path portion 2151.

[0062] Furthermore, in Modification 5, a second flow path section 2152 with high flow path resistance is provided near the inlet. Therefore, the second flow path section 2152 functions as a flow dividing section for the low-temperature fluid, and the low-temperature fluid that passes through the second flow path section 2152 and is divided by the second flow path section 2152 flows into the through-hole 271 while being widely diffused in the wide third flow path section 2153. As a result, the low-temperature fluid is distributed evenly throughout the flow path section 215, improving the heat exchange capacity of the heat exchanger 1.

[0063] In addition, in the sixth modification shown in FIG. 11, the second flow path portion 2152 is disposed closer to the through-hole (outlet) 271 than the through-hole (inlet) 281 .

[0064] In a metal plate that does not have a second flow path section 2152 with high flow path resistance, as in the reference example shown in Figure 6, there is nothing to obstruct the flow of the low-temperature fluid, so the liquid refrigerant flows straight from the inlet to the outlet.

[0065] In contrast, if the second flow path portion 2152 with high flow path resistance is located near the outlet, there will be something blocking the flow of the liquid refrigerant or two-phase refrigerant downstream of the flow path, causing the liquid refrigerant or two-phase refrigerant to detour before reaching the second flow path portion 2152. In other words, if the second flow path portion 2152, which is difficult for the liquid refrigerant to flow through, exists in the flow path, the liquid refrigerant or two-phase refrigerant will first try to flow to the first flow path portion 2151, which is easier for the liquid refrigerant to flow through. As a result, the liquid refrigerant detours before reaching the second flow path portion 2152, increasing the area in the flow path portion 215 where the liquid refrigerant flows.

[0066] In particular, in the metal plate 21, the dryness fraction of the low-temperature refrigerant increases toward the downstream side of the flow path. Therefore, the dryness fraction of the low-temperature fluid is high near the outlet, and the flow velocity of the low-temperature fluid is high near the outlet. As a result, the pressure loss of the low-temperature fluid increases due to the second flow path portion 2152, and the effect of the second flow path portion 2152 as a resistance to the liquid refrigerant or two-phase refrigerant increases.

[0067] For example, for refrigerants with high latent heat, such as ammonia, the circulation rate of the refrigerant flowing through the flow path is set low, resulting in a slower refrigerant flow velocity near the inlet, where the dryness is lower, compared to refrigerants with low latent heat, such as R32 and R134a. Therefore, even if the second flow path section 2152 is installed near the inlet or in the center of the flow path, the refrigerant pressure loss is small, making it difficult for the second flow path section 2152 to function as a flow path section with high flow resistance. In such cases, by placing the second flow path section 2152 in an area where the refrigerant flow velocity is faster, i.e., closer to the outlet than the inlet, the second flow path section 2152 can function as a flow path section with high flow resistance. This prevents the liquid refrigerant from drifting in the metal plate 21.

[0068] Although the embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and various modifications can be made. Each embodiment is not limited to an independent form, and can be combined as far as technically possible.

[0069] DESCRIPTION OF SYMBOLS 1...Heat exchanger 1w...Side surface 1d, 1u...Main surface 2...Heat exchanger body 3, 4, 21, 22, 100...Metal plate 5, 8...Inlet pipe 6, 7...Outlet pipe 15, 16, 17, 18...Space portion 20...Stacked body 21L, 100d, 100L...Area 101...Virtual line 150, 160, 170, 180...Opening 210, 220...Recess 211, 221...Area 212, 222...Partition wall 213, 223...Outer periphery 214, 224...Protrusion 215, 225...Flow path portion 251, 261, 272, 282...Through hole 252...Through hole (inlet) 262...Through hole (outlet) 271...Through hole (outlet) 281...Through hole (inlet) 2141, 2142, 2142a, 2142b, 2142c, 2142d, 2143, 2145...protrusions 2151...first flow path section 2152...second flow path section 2153...third flow path section

Claims

1. A heat exchanger in which a plurality of metal plates are stacked, at least one of the plurality of metal plates has an inlet, an outlet, a partition wall, and a plurality of protrusions protruding from the partition wall, a flow path portion is formed on the partition wall by the plurality of protrusions, the flow path portion has a first flow path portion, a second flow path portion, and a third flow path portion between the inlet and the outlet, the first flow path portion, the second flow path portion, and the third flow path portion are arranged in this order from the inlet to the outlet, and the flow path resistance of the second flow path portion is greater than the flow path resistances of the first flow path portion and the third flow path portion.

2. A heat exchanger according to claim 1, wherein the flow path cross-sectional area of ​​the second flow path portion is smaller than the flow path cross-sectional areas of the first flow path portion and the third flow path portion.

3. A heat exchanger as described in claim 2, wherein, in the second flow path section, the area occupied by the protrusions per unit area of ​​the second flow path section is higher than the area occupied by the protrusions per unit area of ​​the first flow path section and the third flow path section, respectively.

4. A heat exchanger according to claim 1 or 2, wherein the second flow path portion is disposed closer to the inlet than to the outlet.

5. A heat exchanger according to claim 1 or 2, wherein the second flow path portion is disposed closer to the outlet than the inlet.

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