Plate heat exchanger

Abstract

The plate heat exchanger is characterized in that a first plate sheet is provided with a first plate flat part, a first separation rib and a first protrusion, the first separation rib protrudes relative to the first plate flat part, the first protrusion protrudes relative to the first plate flat part, the first plate sheet is provided with a first angle hole and a second angle hole, the first corner hole and the second corner hole are located in the two sides of the separating rib, the connecting line of the centers of the first corner hole and the second corner hole serves as the width direction, the first separating rib is provided with a blocking part, the distance, extending in the width direction, of the blocking part is defined as the first distance, and the second distance is defined as the second distance. The distance of the first protrusions in the width direction is defined as a second distance, and the first distance is at least two times of the second distance. The plate heat exchanger is uniform in fluid distribution and good in heat exchange effect.

Description

Technical Field

[0001] The present application relates to the technical field of heat exchangers, and in particular to a plate heat exchanger. Background Art

[0002] Plate heat exchangers are used for heat transfer of liquids, usually heat exchange between fluids of two temperatures. Plate heat exchangers can be used in thermal management systems for heat exchange between refrigerants and coolants. Since heat exchange performance is a very important indicator in thermal management systems, the design of plate heat exchangers will take heat exchange performance into special consideration.

[0003] There is a plate heat exchanger in which the inlet and outlet are arranged on the same side based on the method of increasing the fluid flow path, and the inlet and outlet are separated by a partition or other structure in the middle to form a U-shaped channel, so that the flow path of the fluid on the plate is increased to increase the heat exchange performance. Since the fluid is particularly easy to flow at the partition, it is easy to cause a larger fluid flow at the partition and a smaller fluid flow away from the partition, which will cause uneven fluid distribution on the plate, thus affecting the heat exchange performance. Summary of the invention

[0004] The object of the present invention is to provide a plate heat exchanger with relatively uniform fluid distribution.

[0005] In order to achieve the above purpose, the following technical solutions are adopted:

[0006] A plate heat exchanger, comprising a plurality of stacked plates, wherein the plates include at least a first plate and a second plate, the first plate and the second plate are stacked and arranged at intervals, and the plate heat exchanger includes at least a first fluid channel and a second fluid channel, at least a portion of the first fluid channel is located between adjacent first plates and second plates, at least a portion of the second fluid channel is located between adjacent first plates and second plates, and the first fluid channel and the second fluid channel are not connected;

[0007] The first plate piece has a first plate flat portion, a first dividing rib and a first protrusion, the first dividing rib protrudes relative to the first plate flat portion, the first protrusion protrudes relative to the first plate flat portion, the first plate piece has a first corner hole and a second corner hole, the first corner hole and the second corner hole are located on both sides of the dividing rib, and the line connecting the centers of the first corner hole and the second corner hole is the width direction, the first dividing rib has a main body and a blocking portion, the blocking portion protrudes in the width direction of the main body, the distance that the blocking portion protrudes from one side of the main body is defined as a first distance, and the distance of the first protrusion in the width direction is defined as a second distance, and the first distance is at least twice the second distance.

[0008] In the plate heat exchanger of the above technical solution, when the fluid flows along the first dividing rib, it is guided by the blocking part, and because the first distance that the blocking part protrudes from one side of the main body is at least twice the second distance, a larger flow rate can be blocked, so that the fluid encounters greater resistance in the blocking part. Therefore, the fluid can be advantageously made to flow at a position away from the first dividing rib, so that the fluid uniformity is better. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] Figure 1 It is a structural schematic diagram of an implementation mode of a plate heat exchanger of the present invention;

[0010] Figure 2 for Figure 1 A partial cross-sectional schematic diagram of the plate heat exchanger, wherein structures such as the first protrusion are omitted;

[0011] Figure 3 A schematic structural diagram of an embodiment of a first plate of a plate heat exchanger of the present invention;

[0012] Figure 4 for Figure 1 The schematic diagram of a partial cross section of the plate heat exchanger along the length direction shows the matching relationship between the blocking parts of adjacent plates;

[0013] Figure 5 A schematic diagram of partial coordination of a first plate and a second plate in one embodiment of a plate heat exchanger;

[0014] Figure 6 for Figure 1 The schematic diagram of a partial cross section of the plate heat exchanger along the length direction shows the mating relationship of the protrusions of adjacent plates;

[0015] Figure 7 for Figure 1 The schematic diagram of a partial cross section of the plate heat exchanger along the width direction shows the partial matching relationship of the blocking parts of adjacent plates;

[0016] Figure 8 It is a partial cross-sectional schematic diagram along the length direction of another embodiment of a plate heat exchanger, which illustrates the matching relationship between the blocking parts of adjacent plates;

[0017] Fig. 9 It is a structural schematic diagram of another embodiment of the first plate of the plate heat exchanger of the present invention;

[0018] In the figure, a plate heat exchanger 100, a first plate 11, 11', a first plate flat portion 111, a first dividing rib 112, a first protrusion 113, a first corner hole 114, a second corner hole 115, a blocking portion 1121, a main body 1122, an arcuate rib 1123, a first section 1124, a second section 1125, a third section 1126, a first portion 1127, a second portion 1128, a bypass channel 1129, a first end portion 112a, a second end portion 112b; a third corner hole 116, a fourth corner hole 117, a first side portion 118, a second side portion 119; a corner hole corresponding area 1101, a middle heat exchange area 1102, and a flow area 1103; a second plate 12, a second dividing rib 121, and a second plate flat portion 124; a first fluid channel 101, a second fluid channel 102; a length direction L, a width direction W, and a thickness direction H. DETAILED DESCRIPTION

[0019] The following is a detailed description of the specific implementation of the present application in conjunction with the accompanying drawings. It should be understood that the following is only for illustration and does not limit the scope of the present application.

[0020] Reference Figure 1-Figure 2 , Figure 1 A plate heat exchanger 100 is schematically shown, which includes a plurality of stacked plates, wherein the plates include at least a first plate 11 and a second plate 12, wherein the first plate 11 and the second plate 12 are stacked and arranged at intervals, and the plate heat exchanger includes at least a first fluid channel 101 and a second fluid channel 102, wherein at least a portion of the first fluid channel 101 is located between adjacent first plates 11 and second plates 12, and at least a portion of the second fluid channel 102 is located between adjacent first plates 11 and second plates 12, and the first fluid channel 101 and the second fluid channel 102 are not connected.

[0021] As another embodiment, the plate heat exchanger may also have three fluid channels, which can be used for heat exchange of fluids at three temperatures in the plate heat exchanger. Or it may also have more fluid channels, which will not be described here. The plate of the plate heat exchanger may also have a third plate and a fourth plate, which can be set according to the number of fluid channels.

[0022] Specifically, refer to Figure 3 The first plate 11 has a first flat portion 111, a first dividing rib 112 and a first protrusion 113. The first dividing rib 112 protrudes relative to the first flat portion 111, and the first protrusion 113 protrudes relative to the first flat portion 111. The protrusion directions of the first dividing rib 112 and the first protrusion 113 relative to the first flat portion 111 may be the same or different, that is, for a first flat portion 111, the first dividing rib 112 may be recessed relative to the back portion of the first flat portion 111, and the first protrusion 113 may be protruded relative to the front portion of the first flat portion 111.

[0023] The first plate 11 has at least a first corner hole 114 and a second corner hole 115, the first corner hole 114 and the second corner hole 115 are located on both sides of the first dividing rib 112, and the line connecting the centers of the first corner hole 114 and the second corner hole 115 is the width direction W, the first dividing rib 112 has a blocking portion 1121 extending along the width direction W, the first dividing rib 112 has a main body 1122 and a blocking portion 1121, the blocking portion 1121 protrudes in the width direction W of the main body 1122, the distance that the blocking portion 1121 protrudes from one side of the main body is defined as a first distance W1, the distance of the first protrusion 113 in the width direction W is defined as a second distance W2, and the first distance W1 is at least twice the second distance W2.

[0024] In this way, when the fluid flows along the first dividing rib, it is guided by the blocking part, and because the first distance of the blocking part protruding from the main body is at least twice the second distance of the first protrusion, it can block a large flow, so that the fluid encounters a larger resistance at the blocking part, thus, it can be advantageous to make the fluid flow away from the first dividing rib, so that the fluid is more uniform. The first distance W1 is preferably 3 to 4 times the second distance W2.

[0025] The blocking portion 1121 may protrude from both sides of the main body, as shown in the embodiment. In this case, the distance W1 protruding from one side of the main body and the distance W1 protruding from the other side of the blocking portion may be the same or different. As a preferred embodiment, the distances W1 protruding from both sides are the same to form a symmetrical structure.

[0026] The first plate 11 further has a third corner hole 116 and a fourth corner hole 117 . The first corner hole 114 and the second corner hole 115 are part of the first fluid channel 101 , and the third corner hole 116 and the fourth corner hole 117 are part of the second fluid channel 102 .

[0027] The structure of the second plate 12 is similar to that of the first plate 11. The second plate 12 also has a first corner hole 114, a second corner hole 115, a third corner hole 116, and a fourth corner hole 117. The second plate 12 has a second dividing rib 121 and a second protrusion (not shown). The third corner hole 116 and the fourth corner hole 117 are located on both sides of the second dividing rib 121. The line connecting the centers of the third corner hole 116 and the fourth corner hole 117 is the width direction W. The second dividing rib 121 has a second blocking portion (not shown) extending along the width direction W. The structure of the second dividing rib refers to that of the first dividing rib.

[0028] In order to more clearly describe the fluid relationship, the fluid flowing in the first fluid channel 101 is defined as the first fluid, and the fluid flowing in the second fluid channel 102 is defined as the second fluid. Through the cross stacking of the first plate 11 and the second plate 12, the first fluid entering from the first corner hole 114 flows on one side of the first plate 11, passes through the obstruction of the first dividing rib 112, flows in the first plate 11 in a roughly U-shaped manner, and then leaves from the second corner hole 115. The second fluid entering from the third corner hole 116 flows on the other side of the first plate 11, passes through the obstruction of the second dividing rib 121, flows in the second plate 12 in a roughly U-shaped manner, and then leaves from the fourth corner hole 117. In this way, the flow paths of the first fluid and the second fluid in the plate heat exchanger can be longer, and the fluids are more evenly distributed on the plates through the obstruction of the obstruction portion 1121 of the first dividing rib 112.

[0029] In this embodiment, the first corner holes 114 of each first plate 11 are aligned to form a part of the first fluid channel 101, the second corner holes 115 of each first plate 11 are aligned to form a part of the first fluid channel 101, the third corner holes 116 of each first plate 11 are aligned to form a part of the second fluid channel 102, and the fourth corner holes 117 of each first plate 11 are aligned to form a part of the second fluid channel 102.

[0030] Continue to refer to Figure 3 The first partition rib 112 has a main body 1122 and two or more arcuate ribs 1123, the arcuate ribs 1123 protrude relative to the main body 1122 in the width direction W, and the third distance of the arcuate rib 1123 protruding from one side of the main body 1122 is less than the first distance of the blocking portion 1121 protruding from the same side of the main body 1122. The arrangement of the arcuate ribs 1123 can make the flow state of the fluid flowing through the first partition rib 112 fluctuate more, so that the fluid has a greater turbulent effect at the first partition rib 112, which is conducive to uniform distribution of the fluid.

[0031] Reference Figure 4 The first dividing rib 112 and the second dividing rib 121 are aligned, the raised side of the first dividing rib 112 and the recessed side of the second dividing rib 121 are abutted against each other, and are welded and fixed. In this way, the welding of the first dividing rib 112 and the second dividing rib 121 blocks the fluid communication between the straight-line distance of the first corner hole 114 and the second corner hole 115, so that the fluid can flow along a roughly U-shaped path.

[0032] Reference Figure 5The top of the first protrusion 113 of the first plate 11 and the second flat portion 124 of the second plate 12 are welded and fixed. In this way, multiple first protrusions 113 of the first plate 11 and the second plate 12 are welded and fixed, which is beneficial to enhancing the welding strength between the first plate 11 and the second plate 12. At the same time, the fluid can flow along the gaps between adjacent first protrusions 113, and the turbulence effect is better.

[0033] Return to reference Figure 3 , the first distance of the blocking portion 1121 protruding from the main body 1122 in the width direction W is at least twice the third distance of the arc-shaped rib 1123 protruding from the main body 1122. The setting of the blocking portion 1121 can further block the fluid flowing along the first dividing rib 112 and guide it in a direction away from the first dividing rib 112, so that the fluid can diffuse to the edge of the plate heat exchanger, which helps the fluid to move more fully on the plate and distribute more evenly. When the distance of the arc-shaped rib 1123 protruding from the main body 1122 is different, the first distance of the blocking portion 1121 protruding from the main body 1122 in the width direction W is at least twice the maximum distance of the arc-shaped rib 1123 protruding from the main body. The first plate 11 has a corner hole corresponding area 1101 and a middle heat exchange area 1102, wherein the middle heat exchange area 1102 is located between the corner hole corresponding areas 1101 on both sides, wherein more than two arc-shaped ribs 1123 are located in the middle heat exchange area 1102, and a blocking portion 1121 is located in the middle heat exchange area 1102. The blocking portion 1121 and the arc-shaped ribs 1123 are concentrated in the middle heat exchange area 1102, which is beneficial to the heat exchange effect of the middle heat exchange area 1102 and makes the fluid distribution more uniform.

[0034] The first dividing rib 112 extends along the length direction L of the first plate 11. The first plate 11 has a first side portion 118 and a second side portion 119 arranged along the length direction L. The first dividing rib 112 is connected to the first side portion 118. A flow area 1103 is defined between the first dividing rib 112 and the second side portion 119. The end of the first dividing rib 112 connected to the first side portion 118 is a first end portion 112a, and the other end of the first dividing rib 112 is a second end portion 112b. A distance D1 between the first end portion 112a and the blocking portion 1121 is between 1 / 2 and 6 / 7 of the length D2 of the first dividing rib 112.

[0035] The distance between the blocking portion 1121 and the first end portion 112a can be used to effectively intercept the fluid flowing along the first dividing rib 112, so that the fluid resistance at the first dividing rib 112 is increased, which is conducive to uniform distribution of the fluid.

[0036] In one embodiment, referring to Figure 5The fourth distance D1 between the first end portion 112a and the blocking portion 1121 is about 2 / 3 of the length D2 of the first dividing rib 112. The first dividing rib 112 has a first section 1124 and a second section 1125. The first section 1124 and the second section 1125 have the same protruding direction. The first end portion 112a is located in the first section 1124, and the arc-shaped rib 1123 is located in the second section 1125. The protruding height of the first section 1124 is lower than that of the second section 1125. The protruding top of the first section 1124 of the first plate 11 is welded and fixed to the first plate flat portion 111 of the second plate 12.

[0037] In one embodiment, the first dividing rib 112 has a first section 1124, a second section 1125, a third section 1126, and a blocking portion 1121 is located between the second section 1125 and the third section 1126, the first end 112a is located in the first section 1124, the arc rib 1123 is located in the second section 1125 and the third section 1126, the second section 1125 and the third section 1126 are symmetrically arranged, and the blocking portion 1121 is located in the middle position of the first plate 11. In this way, the structure of the first plate 11 and the second plate 12 can be made into the same plate by stamping, and it only needs to be assembled after rotating the plate 180° during assembly. This method is simple to process.

[0038] In the above embodiment, the first dividing rib 112 extends along the length direction L of the first plate 11, and the first plate 11 has a first side portion 118 and a second side portion 119 arranged along the length direction L. The first dividing rib 112 is connected to the first side portion 118, and a flow area 1103 is provided between the first dividing rib 112 and the second side portion 119. The end at which the first dividing rib 112 is connected to the first side portion 118 is the first end portion 112a, and the other end of the first dividing rib 112 is the second end portion 112b. The blocking portion 1121 is located in the middle position of the first plate 11 in the length direction L, and the arc-shaped ribs 1123 on both sides of the blocking portion 1121 have the same structure.

[0039] In one embodiment, the first partition rib 112 extends along the length direction L of the first plate 11, and the first plate 11 has a first side portion 118 and a second side portion 119 arranged along the length direction L. The first partition rib 112 is connected to the first side portion 118, and a flow area 1103 is provided between the first partition rib 112 and the second side portion 119. One end of the first partition rib 112 connected to the first side portion 118 is the first end 112a, and the other end of the first partition rib 112 is the second end 112b. From the first end 112a to the blocking portion 1121, the arc of the arc-shaped rib 1123 gradually increases. The gradually increasing arc of the arc-shaped rib 1123 can be used to effectively guide the fluid, reduce the flow resistance, and facilitate the flow of the fluid.

[0040] Reference Figure 7The blocking portion 1121 has a first portion 1127 and a second portion 1128 protruding from one side of the main body 1122 in the width direction W. The second portion 1128 is farther away from the main body 1122 than the first portion 1127. Along the thickness direction H of the plate heat exchanger, the height of the second portion 1128 is less than the height of the first portion 1127. The first fluid channel 101 has a bypass channel 1129. The bypass channel 1129 is located between the first portion 1127 and the second portion 1128. The bypass channel 1129 is formed between the second portion 1128 of the first plate 11 and the second plate flat portion 124 of the second plate 12. The flow area of ​​the bypass channel 1129 is less than the flow area between adjacent first protrusions 113. In this way, the blocking portion 1121 has a blocking effect on the fluid, and the blocking portion 1121 is longer than the arc-shaped rib 1123. Therefore, the setting of the bypass channel 1129 can facilitate the guidance of the fluid at the blocking portion 1121, and the area is unlikely to have a fluid dead zone due to the existence of the bypass channel 1129, which is beneficial to the uniformity of fluid distribution.

[0041] As other embodiments, refer to Figure 8 At least part of the first dividing rib 112 of the first plate 11 is located inside the second dividing rib 121 of the second plate 12, and the raised tops of the first dividing rib 112 of the adjacent first plate 11 and the second dividing rib 121 of the second plate 12 are welded and fixed. In this way, the welding position is at the raised tops of the first dividing rib 112 and the second dividing rib 121, which is convenient for welding.

[0042] As another embodiment, refer to Fig. 9 The first dividing rib 112 includes a first section 1124, a second section 1125, and a third section 1126, wherein the blocking portion 1121 is located between the second section 1125 and the third section 1126, the first end portion 112a is located in the first section 1124, the arc-shaped rib 1123 is located between the second section 1125 and the third section 1126, the second section 1125 is connected to the first section 1124, and the distance between the first end portion 112a and the blocking portion 1121 is between 4 / 5 and 6 / 7 of the length D2 of the first dividing rib 112, and there is a longer flow path in front of the blocking portion 1121 so that the fluid is guided along the first dividing rib 112.

[0043] In this embodiment, since the second section 1125 and the third section 1126 are asymmetrical structures, at least two plates need to be processed during manufacturing, namely, the first plate 11 and the second plate 12, which are welded together. The first plate 11 and the second plate 12 can be made by stamping technology.

[0044] It should be noted that the above embodiments are only used to illustrate the present invention but not to limit the technical solutions described in the present invention, such as the directional definitions of "front", "back", "left", "right", "up" and "down". Although the present invention has been described in detail in this specification with reference to the above embodiments, it should be understood by those skilled in the art that the present invention can still be combined, modified or replaced by each other, and all technical solutions and improvements thereof that do not depart from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A plate heat exchanger, comprising a plurality of stacked plates, the plates comprising at least a first plate (11) and a second plate (12), the first plate (11) and the second plate (12) being stacked and arranged at intervals, the plate heat exchanger comprising at least a first fluid channel (101) and a second fluid channel (102), at least a portion of the first fluid channel (101) being located between adjacent first plates (11) and second plates (12), at least a portion of the second fluid channel (102) being located between adjacent first plates (11) and second plates (12), and the first fluid channel (101) and the second fluid channel (102) being not connected; It is characterized in that The first plate (11) comprises a first plate flat portion (111), a first dividing rib (112) and a first protrusion (113), wherein the first dividing rib (112) protrudes relative to the first plate flat portion (111), and the first protrusion (113) protrudes relative to the first plate flat portion (111), and the first plate (11) comprises at least a first corner hole (114) and a second corner hole (115), wherein the first corner hole (114) and the second corner hole (115) are located on both sides of the first dividing rib (112), and the first corner hole (114) and the second corner hole (115) are located on both sides of the first dividing rib (112). The line connecting the center of the first corner hole (114) and the center of the second corner hole (115) is the width direction (W), the first dividing rib (112) has a main body (1122) and a blocking portion (1121), the blocking portion protrudes in the width direction (W) of the main body, the distance that the blocking portion (1121) protrudes from one side of the main body is defined as a first distance (W1), the distance of the first protrusion (113) in the width direction (W) is defined as a second distance (W2), and the first distance (W1) is at least twice the second distance (W2).

2. The plate heat exchanger according to claim 1, characterized in that: The first dividing rib (112) has more than two arc-shaped ribs (1123), and the arc-shaped ribs (1123) protrude relative to the main body (1122) in the width direction (W), and a third distance of the arc-shaped ribs (1123) protruding from one side of the main body (1122) is smaller than a first distance of the blocking portion (1121) protruding from the same side of the main body (1122).

3. The plate heat exchanger according to claim 2, characterized in that: A first distance by which the blocking portion (1121) protrudes from one side of the main portion (1122) in the width direction (W) is at least twice a third distance by which the arc-shaped rib portion (1123) protrudes from the same side of the main portion (1122).

4. The plate heat exchanger according to claim 2, characterized in that: The first plate (11) comprises a corner hole corresponding area (1101) and a middle heat exchange area (1102); the corner hole corresponding area (1101) is located on both sides of the first plate (11); the middle heat exchange area (1102) is located between the corner hole corresponding areas (1101) on both sides; the two or more arc-shaped ribs (1123) are located in the middle heat exchange area (1102); and the blocking portion (1121) is located in the middle heat exchange area (1102).

5. The plate heat exchanger according to any one of claims 1 to 4, characterized in that: The first dividing rib (112) extends along the length direction (L) of the first plate (11); the first plate (11) has a first side portion (118) and a second side portion (119) arranged along the length direction (L); the first dividing rib (112) is connected to the first side portion (118); a flow area (1103) is provided between the first dividing rib (112) and the second side portion (119); one end of the first dividing rib (112) connected to the first side portion (118) is a first end portion (112a); the other end of the first dividing rib (112) is a second end portion (112b); and the distance between the first end portion (112a) and the blocking portion (1121) is between 1 / 2 and 6 / 7 of the length of the first dividing rib (112).

6. The plate heat exchanger according to claim 5, characterized in that: A fourth distance (D1) between the first end portion and the blocking portion (1121) is 2 / 3 of the length (D2) of the first dividing rib (112); the first dividing rib (112) comprises a first section (1124) and a second section (1125); the first section (1124) and the second section (1125) have the same protruding direction; the first end portion (112a) is located in the first section (1124); the arc-shaped rib (1123) is located in the second section (1125); the protruding height of the first section (1124) is lower than that of the second section (1125); the protruding top of the first section (1124) of the first plate (11) and the second flat section (124) of the second plate (12) are welded and fixed.

7. The plate heat exchanger according to claim 2, 3 or 4, characterized in that: The first dividing rib (112) extends along the length direction (L) of the first plate (11); the first plate (11) has a first side portion (118) and a second side portion (119) arranged along the length direction (L); the first dividing rib (112) is connected to the first side portion (118); a flow area (1103) is provided between the first dividing rib (112) and the second side portion (119); one end of the first dividing rib (112) connected to the first side portion (118) is a first end portion (112a); the other end of the first dividing rib (112) is a second end portion (112b); and from the first end portion (112a) to the blocking portion (1121), the arc shape of the arc-shaped rib (1123) gradually becomes larger.

8. The plate heat exchanger according to claim 5, characterized in that: The first dividing rib (112) comprises a first section (1124), a second section (1125), and a third section (1126); the blocking portion (1121) is located between the second section (1125) and the third section (1126); the first end portion is located in the first section (1124); the arc-shaped rib (1123) is located in the second section (1125) and the third section (1126); the second section (1125) and the third section (1126) are symmetrically arranged, and the blocking portion (1121) is located in the middle of the first plate (11).

9. The plate heat exchanger according to claim 8, characterized in that: The blocking portion (1121) comprises a first portion (1127) and a second portion (1128) which protrude from one side of the main body portion (1122) in the width direction (W); the second portion (1128) is farther away from the main body portion (1122) than the first portion (1127); along the thickness direction of the plate heat exchanger, the height of the second portion (1128) is smaller than the height of the first portion (1127); the first fluid channel (101) comprises a bypass channel (1129) which is located between the first portion (1127) and the second portion (1128); and the flow area of ​​the bypass channel (1129) is smaller than the flow area between adjacent first protrusions (113).

10. The plate heat exchanger according to claim 7 or 8, characterized in that: The second plate (12) has a second dividing rib (121), the first dividing rib and the second dividing rib protrude in the same direction, at least part of the first dividing rib (112) is located inside the second dividing rib (121), and the protruding tops of the adjacent first dividing rib (112) and second dividing rib (121) are welded and fixed; or the first dividing rib (112) and the second dividing rib (121) are aligned, and the protruding side portion of the first dividing rib (112) and the recessed side portion of the second dividing rib (121) are abutted against and welded and fixed.

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