Plate sheet group of heat exchanger

Abstract

The invention relates to the technical field of heat exchangers, in particular to a heat exchanger plate sheet group which comprises at least two pairs of unit plate sheet groups, each pair of unit plate sheet groups comprises equal-height corrugated plate sheets and non-equal-height corrugated plate sheets which are arranged in a stacked mode, and the equal-height corrugated plate sheets and the non-equal-height corrugated plate sheets are provided with corresponding first angle holes; a first sealing face is arranged on the periphery of a first angle hole in the back face of the equal-height corrugated plate, a second sealing face is arranged on the periphery of a first angle hole of the non-equal-height corrugated plate, the first sealing face and the second sealing face which are complementary are arranged on the periphery of a refrigerant inlet, and the first sealing face and the second sealing face are tightly attached to form a sealing area after the plate set is stacked. Therefore, the water flow can be forced to quickly flow to the water side outlet along the outer edge of the sealing surface, the water flow is prevented from stagnation of too low flow speed near the R angle, and the formation condition of low-temperature icing on the water side is blocked from the source; in addition, by adopting a porous distribution structure with different pore diameters, the heat exchanger can exert the optimal heat exchange performance at the same time during refrigeration and heating.

Description

Technical Field

[0001] This invention relates to the field of heat exchanger technology, and in particular to a heat exchanger plate assembly. Background Technology

[0002] A plate heat exchanger is a high-efficiency heat exchanger made of a series of corrugated metal plates stacked and brazed. Heat exchange occurs through channels formed between the plates. Compared to traditional shell-and-tube heat exchangers, brazed plate heat exchangers have a much higher heat transfer coefficient and are more efficient in heat transfer.

[0003] In heat pump heating applications, when a plate heat exchanger operates as an evaporator, the temperature of the refrigerant entering the plate inlet is often below -20 degrees Celsius. The metal temperature near the inlet drops sharply as a result. If the water flow rate is low during this period, or if the water flow through the inlet area slows down or stagnates, a stagnant zone can easily form near the refrigerant inlet radius (R-angle). A significant temperature difference exists between the stagnant water and the low-temperature metal surface. Once initial ice crystals form in this area, their expansion rapidly pushes the surrounding water to freeze further, causing abnormal local stress on the plate and potentially leading to plate freezing and cracking or even leakage failure. This failure mode, "from local stagnation to overall freezing and cracking," is quite common in engineering practice and is difficult to restore through repair once it occurs.

[0004] Existing engineering methods often mitigate freezing risks by limiting minimum water flow rates via software, incorporating anti-freeze electric heating into the system, or implementing control strategies for early shutdown. However, these measures are system-level control mechanisms and cannot fundamentally alter the flow patterns within the inlet area of ​​the refrigerant plates. Under complex operating conditions such as extreme outdoor temperatures, unauthorized flow rate adjustments by users, or frequent unit start-ups and shutdowns, localized stagnation and freezing can still occur in the refrigerant inlet area. Especially in compact plate heat exchangers, the complex patterns designed for higher heat transfer performance can sometimes exacerbate uneven local flow velocities near the inlet, further amplifying the freezing risk. Summary of the Invention

[0005] To address the problem of water-side stagnation and freezing in the refrigerant inlet radius (R-angle) region of existing plate heat exchangers, this invention provides a heat exchanger plate assembly. By setting complementary first and second sealing surfaces on the outer periphery of the refrigerant inlet and tightly fitting them together after the plate assembly is stacked to form a sealing area, the water flow can be forced to flow rapidly along the outer edge of the sealing surface to the water-side outlet, avoiding excessively low-speed stagnation of water flow near the R-angle and fundamentally blocking the conditions for low-temperature freezing on the water side.

[0006] The technical solution adopted by this invention to solve its technical problem is: A heat exchanger plate assembly includes at least two pairs of unit plate assemblies. Each pair of unit plate assemblies includes stacked corrugated plates of equal height and non-equal height. Both the corrugated plates of equal height and non-equal height include a main panel and surrounding baffles. The main panel includes a main heat exchange zone and flow guiding zones disposed on both sides of the main heat exchange zone. The equal-height corrugated plates and the non-equal-height corrugated plates have corresponding first corner holes, and the first corner holes are refrigerant inlets; the outer periphery of the first corner hole on the back of the equal-height corrugated plate is provided with a first sealing surface, and the outer periphery of the first corner hole of the non-equal-height corrugated plate is provided with a second sealing surface. The first sealing surface and the second sealing surface are bonded together after the plates are stacked to form a sealing area, which is used to prevent water medium from flowing around the first corner hole.

[0007] Optionally, the main panel of the equal-height corrugated plate is provided with a plurality of front ridges, and a front valley is formed between adjacent front ridges; the back of the equal-height corrugated plate forms a back valley at a position corresponding to the front ridge, and a back ridge at a position corresponding to the valley. The flow guiding area of ​​the non-uniform height corrugated plate is provided with several front convex ridges II, and front concave valleys II are formed between adjacent front convex ridges II; the main heat exchange area of ​​the non-uniform height corrugated plate is also provided with front convex ridges III that are not equal in height to the front convex ridges II, and front convex ridges II and front convex ridges III are arranged alternately to form front concave valleys III. The front ridge of the non-uniform height corrugated plate guide area is provided with several protrusions, and the protrusions are in contact with the back ridge of the uniform height corrugated plate guide area to form a connecting surface.

[0008] Optionally, the second sealing surface has the same height as the protrusion, and a guide groove is formed between the front ridge of the guide area on the non-uniform height corrugated plate and the second sealing surface.

[0009] Optionally, the width W of the guide groove is 1.5-3mm.

[0010] Optionally, a plurality of grooves are formed on the second sealing surface, and a boss is formed between adjacent grooves; the grooves are intersected with the back concave valley of the equal-height corrugated plate guide area, and the back ridge of the equal-height corrugated plate contacts the boss.

[0011] Optionally, the equal-height corrugated plate and the non-equal-height corrugated plate also have corresponding second corner holes, third corner holes and fourth corner holes; the center distance d1 between the first corner hole and the second corner hole is asymmetrical about the horizontal center line of the plate; the center distance d3 between the third corner hole and the fourth corner hole is symmetrical about the horizontal center line of the plate; the center distance d2 between the second corner hole and the third corner hole is asymmetrical about the vertical center line of the plate; the center distance d4 between the first corner hole and the fourth corner hole is asymmetrical about the vertical center line of the plate.

[0012] Optionally, the center distance d1 between the first corner hole and the second corner hole is 4-8 mm larger than the center distance d3 between the third corner hole and the fourth corner hole; the center distance d4 between the first corner hole and the fourth corner hole is 4-8 mm larger than the center distance d2 between the second corner hole and the third corner hole.

[0013] Optionally, a distribution groove is provided around the first corner hole on the non-uniform height corrugated plate and communicates with it. A distribution protrusion one and a distribution protrusion two are provided on the distribution groove. A distribution hole one is provided on the distribution protrusion one and a distribution hole two is provided on the distribution protrusion two.

[0014] Optionally, the diameter of the first distribution hole is 0.1 mm to 0.4 mm larger than the diameter of the second distribution hole.

[0015] Optionally, an angle α is formed between the center line of the first distribution protrusion and the vertical center line of the first corner hole, and an angle b is formed between the center line of the second distribution protrusion and the vertical center line of the first corner hole, wherein the angle α is 10°-30° and the angle b is 15°-35°.

[0016] The beneficial effects of this invention are: The heat exchanger plate assembly provided by this invention, by setting complementary first and second sealing surfaces on the outer periphery of the refrigerant inlet, and making them tightly fitted after the plate assembly is stacked to form a sealing area, prevents water-side fluid from entering the low-temperature R-corner region around the first corner hole in the water-plate channel. This sealing area can force the water flow to flow rapidly along the outer edge of the sealing surface to the water-side outlet, avoiding the water flow from stagnating at too low a speed near the R-corner, thus fundamentally blocking the formation conditions of low-temperature freezing on the water side. Furthermore, this anti-freeze structure effectively avoids the risk of plate freezing and cracking and refrigerant leakage, greatly improving the operational reliability of the plate heat exchanger under harsh conditions such as low water volume and low-temperature heating, while protecting the compressor from damage caused by plate breakage. Attached Figure Description

[0017] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0018] Figure 1 This is a schematic diagram of the front structure of the equal-height corrugated plate of the present invention; Figure 2 This is a schematic diagram of the front structure of the non-uniform height corrugated plate of the present invention; Figure 3 yes Figure 2 Enlarged view of point A in the middle; Figure 4 This is a schematic diagram of the unit plate assembly in this invention. Figure 1 ; Figure 5 yes Figure 4 Enlarged view of point B in the middle; Figure 6 This is a schematic diagram of the unit plate assembly in this invention. Figure 2 ; Figure 7 This is a schematic diagram of the unit plate assembly in this invention. Figure 3 ; Figure 8 yes Figure 7 Enlarged view of point C in the middle; Figure 9 This is a schematic diagram of the unit plate assembly in this invention. Figure 4 ; Figure 10 This is a schematic diagram of the unit plate assembly in this invention. Figure 5 ; Figure 11 This is a schematic diagram of the heat exchanger plate assembly in this invention; Figure 12 This is a cross-sectional view of the heat exchanger plate assembly in this invention; In the diagram: 01. First corner hole, 02. Second corner hole, 03. Third corner hole, 04. Fourth corner hole, 1. Equal-height corrugated plate, 11. First sealing surface, 12. Front ridge one, 13. Front valley one, 14. Back valley one, 15. Back ridge one, 16. Connecting surface, 17. Distribution groove, 171. Distribution protrusion one, 1711. Distribution hole one, 172. Distribution protrusion two, 1721. Distribution hole two, 18. Effective welding surface, 2. Non-equal-height corrugated plate, 21. Second sealing surface, 211. Groove, 212. Boss, 22. Front ridge two, 221. Protrusion, 23. Front valley two, 24. 3. Baffle, 4. Main heat exchange zone, 41. Front ridge three, 42. Front valley three, 5. Flow guide zone, 6. Water plate channel, 7. Refrigerant plate channel. Detailed Implementation

[0019] The present invention will now be described in further detail. The embodiments described below are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0021] To address the problem of water-side stagnation and freezing occurring in the refrigerant inlet radius (R-angle) region of existing plate heat exchangers, such as... Figure 1-12 As shown, the present invention provides a heat exchanger plate group, including at least two pairs of unit plate groups. Each pair of unit plate groups includes stacked equal-height corrugated plates 1 and non-equal-height corrugated plates 2. Both equal-height corrugated plates 1 and non-equal-height corrugated plates 2 include a main panel and surrounding baffles 3. The main panel includes a main heat exchange zone 4 and flow guiding zones 5 disposed on both sides of the main heat exchange zone 4. The heat exchanger plate assembly has a water plate channel 6 and a refrigerant plate channel 7. The water plate channel 6 is located between the front of the non-uniform height corrugated plate 2 and the adjacent uniform height corrugated plate 1, and the refrigerant plate channel 7 is located between the front of the uniform height corrugated plate 1 and the adjacent non-uniform height corrugated plate 2. Furthermore, the equal-height corrugated plate 1 and the non-equal-height corrugated plate 2 have corresponding first corner holes 01, and the first corner holes 01 are refrigerant inlets; the outer periphery of the first corner hole 01 on the back of the equal-height corrugated plate 1 is provided with a first sealing surface 11, and the outer periphery of the first corner hole 01 of the non-equal-height corrugated plate 2 is provided with a second sealing surface 21. The first sealing surface 11 and the second sealing surface 21 are fitted together after the plate assembly is stacked to form a complete sealing area, so that the water-side fluid cannot enter the low-temperature R-angle area around the first corner hole 01 in the water-plate channel 6. This sealing area can force the water flow to flow quickly along the outer edge of the sealing surface to the water-side outlet, avoiding the water flow from stagnating at too low a flow rate near the R-angle, thus blocking the formation conditions of low-temperature freezing on the water side from the root; and this anti-freeze structure effectively avoids the risk of plate freezing and cracking and refrigerant leakage, greatly improving the operational reliability of the plate heat exchanger under harsh conditions such as low-temperature refrigeration and non-steady-state heating at low ambient temperature and low water flow, while protecting the compressor from damage caused by plate cracking.

[0022] In this invention, the first sealing surface 11 and the second sealing surface 21 are bonded together after the plates are stacked to form a sealing area with an effective welding surface 18. Because of the design of this effective welding surface 18, the water flow will not flow through the R-angle of the refrigerant inlet. Furthermore, it is preferred that the size M of the effective welding surface is greater than 2.5 mm, so that the water-side sealing area can obtain a more sufficient welding area during the brazing process, thereby ensuring the welding firmness and sealing reliability.

[0023] The present invention preferably provides a plurality of front ridges 12 on the main panel of the equal height corrugated plate 1, and front valleys 13 are formed between adjacent front ridges 12; the back of the equal height corrugated plate 1 forms back valleys 14 at positions corresponding to the front ridges 12, and back ridges 15 at positions corresponding to the valleys 13. The flow guiding area 5 of the non-uniform height corrugated plate 2 is provided with several front convex ridges 22, and front concave valleys 23 are formed between adjacent front convex ridges 22; the main heat exchange area 4 of the non-uniform height corrugated plate 2 is also provided with front convex ridges 3 41 that are not of the same height as the front convex ridges 22, and front convex ridges 22 and front convex ridges 3 41 are arranged alternately to form front concave valleys 3 42. The front ridge 22 of the non-uniform height corrugated plate 2 flow guide area 5 is provided with a plurality of protrusions 221. In this invention, the height of the protrusions 221 is 0.5mm-1mm, the length is 3.5mm-6mm, the width is 2mm-4mm, and the distance between adjacent protrusions 221 is 1.3mm-2mm. The protrusions 221 are in contact with the back ridge 15 of the uniform height corrugated plate 1 flow guide area 5 and form a connecting surface 16, forming an effective welding surface. Under the premise of ensuring the overall welding strength and reliability of the plate, the welding area and the number of weld points of the flow guide area are significantly increased, thereby effectively improving the local welding strength and pressure bearing capacity of the area.

[0024] Under this structural design, the water-side fluid flows more smoothly when entering the plate guide zone 5 from the third corner hole 03, and the flow resistance is significantly reduced. For the refrigerant side, after the liquid refrigerant flows out, it forms a unique "climbing-downhill" flow path in the refrigerant inter-plate channel 7. This accelerates the inter-plate flow velocity of the refrigerant on the one hand, and on the other hand, through this feature, increases the refrigerant flow resistance and enhances the flow disturbance, thereby generating effective boiling heat transfer in this region, so that the guide zone 5 simultaneously undertakes the functions of guiding flow and assisting heat transfer. In addition, the optimized geometry of the protrusion 221, while ensuring welding reliability, jointly contributes to the above-mentioned enhanced flow and heat transfer effects, ultimately improving the overall heat transfer efficiency of the plate heat exchanger.

[0025] Preferably, the second sealing surface 21 and the protrusion 221 are at the same height, and a water channel 24 is formed between the front ridge 22 of the non-uniform height corrugated plate 2 and the second sealing surface 21. The water channel 24 can guide the water-side fluid to accelerate its flow when passing through the vicinity of the sealing area, effectively increasing the water flow velocity between the plates in this area, so that the fluid can flow to the water-side outlet more quickly, thereby significantly avoiding the risk of freezing caused by water flow stagnation in the low temperature area.

[0026] Furthermore, the present invention preferably has a guide groove 24 width W of 1.5-3mm, wherein the guide groove 24 width W refers to the vertical distance from the lower edge of the arc of the protrusion 221 to the second sealing surface 21. This dimension ensures sufficient drainage capacity while generating a moderate local pressure drop, prompting the water flow to pass through the area around the sealing zone in a more stable and continuous manner, thereby guiding the fluid to enter the outlet efficiently and comprehensively improving the overall performance of the antifreeze structure.

[0027] Preferably, the second sealing surface 21 of the present invention has a plurality of grooves 211 formed thereon, and a boss 212 is formed between adjacent grooves 211. The grooves 211 are intersected with the back concave valleys 14 of the flow guide area 5 of the equal-height corrugated plate 1, and the back ridges 15 of the equal-height corrugated plate 1 are in contact with the bosses 212. On the one hand, this can make the welding support in this area more sufficient, improve the local welding strength and mechanical stability; on the other hand, the grooves 211 form geometric disturbances on the refrigerant side, so that the refrigerant entering the plate heat exchanger can be subjected to secondary enhanced mixing, which helps to reduce the refrigerant temperature gradient in the inlet area, improve the uniformity of the refrigerant flow entering the entire flow guide area 5, and improve the initial heat exchange effect.

[0028] The present invention preferably includes a uniform-height corrugated plate 1 and a non-uniform-height corrugated plate 2, which also have corresponding second corner holes 02, third corner holes 03, and fourth corner holes 04; wherein, the second corner hole 02 is a refrigerant outlet, the third corner hole 03 is a water inlet, and the fourth corner hole 04 is a water outlet; the center distance d1 between the first corner hole 01 and the second corner hole 02 is asymmetrical about the horizontal center line of the plate; the center distance d3 between the third corner hole 03 and the fourth corner hole 04 is symmetrical about the horizontal center line of the plate; the center distance d2 between the second corner hole 02 and the third corner hole 03 is asymmetrical about the vertical center line of the plate; and the center distance d4 between the first corner hole 01 and the fourth corner hole 04 is asymmetrical about the vertical center line of the plate.

[0029] Preferably, the center distance d1 between the first corner hole 01 and the second corner hole 02 is 4-8 mm larger than the center distance d3 between the third corner hole 03 and the fourth corner hole 04; the center distance d4 between the first corner hole 01 and the fourth corner hole 04 is 4-8 mm larger than the center distance d2 between the second corner hole 02 and the third corner hole 03.

[0030] To optimize heat exchange efficiency, this design employs an asymmetrical layout for the corner holes on the plates. Considering the low flow rate of the liquid refrigerant and the need to fully utilize the heat exchange area, the first corner hole 01 is shifted to the lower left. This guides the refrigerant, located at the lowest point of the plate heat exchanger, to diffuse more effectively to all corners between the plates, avoiding flow dead zones and maximizing the effective heat exchange area. Simultaneously, the position of the second corner hole 02 is appropriately lowered to match the high flow rate of the gaseous refrigerant, increasing the flow volume of its outlet channel, promoting rapid gas discharge, and effectively reducing flow pressure drop and the risk of gas blockage. This asymmetrical layout, through optimized matching of the refrigerant inlet and outlet spatial positions, improves the uniformity and flowability of the refrigerant distribution in the inter-plate channels, achieving more complete, stable, and efficient heat exchange.

[0031] Furthermore, in this invention, the horizontal center of the second corner hole 02 is preferably 3-6 mm lower than the horizontal center of the third corner hole 03; and the horizontal center of the first corner hole 01 is 3-6 mm lower than the horizontal center of the fourth corner hole 04.

[0032] Preferably, the distance x1 from the center of the first corner hole 01 to the vertical center line of the plate is 10-16 mm larger than the distance x2 from the center of the fourth corner hole 04 to the vertical center line of the plate; the distance x3 from the center of the second corner hole 02 to the vertical center line of the plate is 1-5 mm smaller than the distance x4 from the center of the third corner hole 03 to the vertical center line of the plate.

[0033] In this invention, a distribution groove 17 is preferably provided around the first corner hole 01 on the non-uniform height corrugated plate 2 and is connected thereto. A distribution protrusion 171 and a distribution protrusion 172 are provided on the distribution groove 17. The distribution protrusion 171 is provided with a distribution hole 1711 and the distribution protrusion 172 is provided with a distribution hole 1721. The number of distribution protrusions can be adjusted according to actual needs. In this invention, the number of distribution protrusions is preferably two.

[0034] The diameters of the first distribution hole 1711 and the second distribution hole 1721 are preferably 0.9 mm to 1.4 mm; and preferably the diameter of the first distribution hole 1711 is 0.1 mm to 0.4 mm larger than the diameter of the second distribution hole 1721.

[0035] Preferably, the center line of the first distribution protrusion 171 and the vertical center line of the first corner hole 01 form an angle α, and the center line of the second distribution protrusion 172 and the vertical center line of the first corner hole 01 form an angle β, wherein the angle α is 10°-30° and the angle β is 15°-35°.

[0036] This invention achieves high reliability, process stability, and excellent refrigerant flow distribution performance by setting a distribution groove 17 with double distribution holes around the first corner hole 01. The punching process of this structure is stable, and the hole diameter tolerance can be controlled within ±0.03mm, ensuring dimensional consistency.

[0037] Its dual-hole design is optimized for both cooling (evaporation) and heating (condensation) conditions: the diameters of the two distribution holes differ by 0.1–0.4 mm; in cooling conditions, this structure promotes more uniform entry of refrigerant into each plate channel, avoiding local overheating or insufficient heat exchange caused by uneven flow; in heating conditions, the lower-positioned, larger-diameter distribution hole 1711 can preferentially guide the liquid refrigerant to flow smoothly, preventing it from accumulating inside the heat exchanger and occupying the effective heat exchange area, thereby helping to reduce the condensing temperature and improve heating performance.

[0038] like Figure 10As shown, when the equal-height corrugated plate 1 and the non-equal-height corrugated plate 2 are stacked one on top of the other (with the non-equal-height corrugated plate 2 on top and the equal-height corrugated plate 1 on the bottom), when the refrigerant is running as an evaporator, it can first enter the refrigerant channel 7 between the distribution holes, and then quickly disperse to both sides of the distribution holes. After a portion of the refrigerant passes through the channel between the front concave valley 13 and the second sealing surface 21 of the equal-height corrugated plate 1, the flow velocity increases and the degree of turbulence increases. Finally, all the refrigerant can enter the guide zone 5 between the plates more evenly. This flow path effectively eliminates the flow dead zone in the inlet area and ensures that the refrigerant can obtain a sufficient and stable flow rate at each position in the guide zone 5.

[0039] The above description is illustrative only and not restrictive of the present invention. Those skilled in the art will understand that many modifications, variations or equivalents can be made without departing from the spirit and scope defined by the appended claims, and all such modifications, variations or equivalents will fall within the protection scope of the present invention.

Claims

1. A heat exchanger gasket plate pack, characterized by: The application relates to a heat exchange plate set, which comprises at least two pairs of unit plate sets, each pair of the unit plate sets comprises isometric corrugated plates (1) and non-isometric corrugated plates (2) arranged in a stack, and the isometric corrugated plates (1) and the non-isometric corrugated plates (2) each comprise a main panel and a surrounding baffle (3), the main panel comprises a main heat exchange area (4) and flow guide areas (5) arranged on both sides of the main heat exchange area (4). The isometric corrugated plates (1) and the non-isometric corrugated plates (2) have corresponding first corner holes (01), and the first corner holes (01) are refrigerant inlets; a first sealing surface (11) is arranged on the outer periphery of the first corner hole (01) on the back of the isometric corrugated plate (1), a second sealing surface (21) is arranged on the outer periphery of the first corner hole (01) of the non-isometric corrugated plate (2), and the first sealing surface (11) and the second sealing surface (21) are attached to form a sealing area after the plate sets are stacked, so as to prevent water medium from flowing around the first corner hole (01).

2. A heat exchanger plate pack according to claim 1, characterised in that: The main panel of the isometric corrugated plate (1) is provided with a plurality of front ridges (12), and front valleys (13) are formed between adjacent front ridges (12); the back of the isometric corrugated plate (1) is provided with a back valley (14) corresponding to the front ridges (12) and a back ridge (15) corresponding to the front valleys (13); The flow guide area (5) of the non-isometric corrugated plate (2) is provided with a plurality of front ridges (22), and front valleys (23) are formed between adjacent front ridges (22); the main heat exchange area (4) of the non-isometric corrugated plate (2) is further provided with front ridges (41) which are non-isometric with the front ridges (22), and the front ridges (22) and the front ridges (41) are alternately arranged to form front valleys (42); The front ridges (22) of the flow guide area (5) of the non-isometric corrugated plate (2) are provided with a plurality of protrusions (221), and the protrusions (221) are in contact with the back ridges (15) of the flow guide area (5) of the isometric corrugated plate (1) and form connecting surfaces (16).

3. A plate pack for a heat exchanger according to claim 2, characterised in that: The second sealing surface (21) and the protrusions (221) have the same height, and the front ridges (22) of the flow guide area (5) of the non-isometric corrugated plate (2) and the second sealing surface (21) form flow guide grooves (24).

4. A plate pack according to claim 3, characterised in that: The width W of the flow guide grooves (24) is 1.5-3 mm.

5. A plate pack according to claim 3, characterised in that: A plurality of grooves (211) are formed on the second sealing surface (21), and a plurality of bosses (212) are formed between adjacent grooves (211); the grooves (211) and the back valleys (14) of the flow guide area (5) of the isometric corrugated plate (1) are arranged in a cross manner, and the back ridges (15) of the isometric corrugated plate (1) are in contact with the bosses (212).

6. A plate pack for a heat exchanger according to claim 1, characterised in that: The equal-height corrugated sheet (1) and the non-equal-height corrugated sheet (2) also have corresponding second corner holes (02), third corner holes (03) and fourth corner holes (04); the center distance d1 between the first corner hole (01) and the second corner hole (02) is asymmetric about the horizontal center line of the sheet; the center distance d3 between the third corner hole (03) and the fourth corner hole (04) is symmetric about the horizontal center line of the sheet; the center distance d2 between the second corner hole (02) and the third corner hole (03) is asymmetric about the vertical center line of the sheet; and the center distance d4 between the first corner hole (01) and the fourth corner hole (04) is asymmetric about the vertical center line of the sheet.

7. The heat exchanger plate pack according to claim 6, characterised in that The center distance d1 between the first corner hole (01) and the second corner hole (02) is 4-8 mm larger than the center distance d3 between the third corner hole (03) and the fourth corner hole (04); and the center distance d4 between the first corner hole (01) and the fourth corner hole (04) is 4-8 mm larger than the center distance d2 between the second corner hole (02) and the third corner hole (03).

8. The heat exchanger plate pack according to claim 6, characterised in that The first corner hole (01) on the non-equal-height corrugated sheet (2) is provided with a distribution groove (17) in communication therewith, a distribution protrusion one (171) and a distribution protrusion two (172) are formed on the distribution groove (17), a distribution hole one (1711) is arranged on the distribution protrusion one (171), and a distribution hole two (1721) is arranged on the distribution protrusion two (172).

9. The heat exchanger plate pack according to claim 8, characterised in that The diameter of the distribution hole one (1711) is 0.1-0.4 mm larger than the diameter of the distribution hole two (1721).

10. The heat exchanger plate pack according to claim 8, characterised in that An included angle a is formed between the center line of the distribution protrusion one (171) and the vertical center line of the first corner hole (01), an included angle b is formed between the center line of the distribution protrusion two (172) and the vertical center line of the first corner hole (01), the included angle a is 10-30°, and the included angle b is 15-35°.

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