Microchannel heat exchanger and method for manufacturing the same

Abstract

The present invention discloses a microchannel heat exchanger and a manufacturing method thereof, which relates to the technical field of heat exchange equipment, and includes a high-pressure side flow channel unit and a low-pressure side flow channel unit that are alternately stacked, the high-pressure side flow channel unit includes a flow channel plate and a unit cover plate covering one side of the flow channel plate, a high-pressure side microchannel for high-pressure fluid to pass through is arranged between the flow channel plate and the unit cover plate, and the material of the flow channel plate and the unit cover plate is a first material; a coating plate is arranged on the side of the flow channel plate away from the unit cover plate and the side of the unit cover plate away from the flow channel plate, and the material of the coating plate is a second material, and the first material and the second material are different; the low-pressure side flow channel unit includes a low-pressure side channel for low-pressure fluid to pass through, and the low-pressure side channel is located between the coating plates of two adjacent high-pressure side flow channel units. The high-pressure side and the low-pressure side in this embodiment can select materials with different properties to meet the needs of high-pressure fluid and low-pressure fluid, which is conducive to improving the application range of high- and low-pressure heat exchangers.

Description

Technical Field

[0001] The present invention relates to the technical field of heat exchange equipment, and in particular to a microchannel heat exchanger and a manufacturing method thereof. Background Art

[0002] Microchannel heat exchanger is an efficient and compact heat exchange device that achieves excellent heat exchange performance by transferring fluid in tiny channels. Compared with traditional heat exchangers, microchannel heat exchangers have many advantages, such as: efficient heat exchange, the small size of the microchannel shortens the heat transfer distance between the fluid and the solid, thereby improving the heat exchange efficiency; fast response, due to its small size and low heat capacity, the microchannel heat exchanger can respond to temperature changes more quickly; energy saving and environmental protection, the microchannel heat exchanger can reduce the energy consumption of equipment operation due to its efficient heat exchange characteristics, and achieve energy saving and emission reduction; compact structure, the compact design of the microchannel heat exchanger makes it suitable for scenarios with limited space, such as automobiles, aerospace and other fields.

[0003] As a typical representative of microchannel heat exchangers, printed circuit board heat exchangers have higher reliability and broad application prospects in nuclear energy, petrochemical industry, oil and gas technology, aerospace, fuel cells and new energy.

[0004] The manufacturing path of printed circuit board heat exchangers can be summarized into three main parts: channel plate etching, heat exchanger core diffusion welding, and external head tube box welding. Limited by the diffusion welding process and equipment, PCHE heat exchangers have fewer material systems to choose from, mainly limited to low-carbon austenitic stainless steel and some high-temperature alloys. In some heat exchanger scenarios, the corrosiveness of cold and hot working fluids is different, so that one material cannot meet the corrosive requirements of both materials at the same time; or a certain working fluid is highly dependent on a specific material, but the welding reliability of this material is relatively weak; or a specific material is expensive, and the use of all this material loses the economic feasibility of the heat exchanger. The above situation greatly limits the scope of application scenarios of heat exchangers.

[0005] As printed circuit board heat exchangers are promoted from test prototypes to engineering projects, more and more new application scenarios are emerging. However, the current manufacturing of printed circuit board heat exchangers is basically limited to austenitic stainless steel. For some occasions with special corrosion resistance requirements, austenitic stainless steel can no longer meet the needs of engineering, and it is necessary to introduce diversified materials. However, diffusion welding is a solid-phase welding technology without solder, and its implementation process depends on the diffusion and recrystallization of material atoms. For martensitic stainless steel or ferritic stainless steel with a high carbon content, it is difficult to achieve 100% transcrystalline connection of a large area of ​​the material, making the plasticity, toughness, and fatigue performance of the welded joint much lower than that of the parent material, so it cannot be used in high-pressure heat exchangers. Material limitations also limit the wider application of printed circuit board heat exchangers.

[0006] In view of this, the present invention is proposed. Summary of the invention

[0007] The object of the present invention is to provide a microchannel heat exchanger and a method for manufacturing the same.

[0008] The present invention is achieved in that:

[0009] In a first aspect, the present invention provides a microchannel heat exchanger, comprising a high-pressure side flow channel unit and a low-pressure side flow channel unit alternately stacked,

[0010] The high-pressure side flow channel unit comprises a flow channel plate and a unit cover plate covering one side of the flow channel plate, a high-pressure side microchannel for high-pressure fluid to pass through is arranged between the flow channel plate and the unit cover plate, and the material of the flow channel plate and the unit cover plate is a first material; a coating plate is arranged on one side of the flow channel plate away from the unit cover plate and on one side of the unit cover plate away from the flow channel plate, and the material of the coating plate is a second material, and the first material and the second material are different;

[0011] The low-pressure side flow channel unit comprises a low-pressure side channel for low-pressure fluid to pass through, and the low-pressure side channel is located between the cladding plates of two adjacent high-pressure side flow channel units.

[0012] In an optional embodiment, both ends of the high-pressure side microchannel are provided with high-pressure fluid cavities, and both of the two high-pressure fluid cavities are provided with high-pressure fluid pipes;

[0013] A partition plate for separating the high-pressure fluid cavity and the low-pressure side channel is arranged between each of the low-pressure side channels and the high-pressure fluid cavity. The partition plate includes a thin pad arranged on the side of the unit cover plate away from the corresponding flow channel plate, and a thick pad is also arranged between the thin pads corresponding to two adjacent high-pressure side flow channel units.

[0014] In an optional embodiment, a coating strip is further provided on one side of the thick pad close to the low-pressure side channel;

[0015] And / or, the material of the component that can contact the high-pressure fluid is a first material, and the material of the component that can contact the low-pressure fluid is a second material.

[0016] In an optional embodiment, the flow channel plate and the unit cover plate are both provided with a recessed portion for accommodating the cladding plate, and the difference between the thickness of the cladding plate and the depth of the recessed portion is ≥1 mm.

[0017] In an optional embodiment, low-pressure fluid cavities communicating with the low-pressure side channel are provided on both sides of each of the high-pressure fluid cavities, and a low-pressure fluid inlet and outlet is provided on each of the low-pressure fluid cavities.

[0018] In an optional embodiment, the cladding plate is provided with a low-pressure side partition bar on one side of the low-pressure side channel, and the low-pressure side partition bar includes an edge support partition bar and an internal support guide partition bar; and / or, the low-pressure side partition bar includes an inlet and outlet guide bar, and the inlet and outlet guide bars are arranged along the low-pressure fluid cavity toward the center of the cladding plate.

[0019] In a second aspect, the present invention provides a method for manufacturing the microchannel heat exchanger according to the aforementioned embodiment, comprising:

[0020] Step A: Assembling the cladding plate, the thin pad plate, the flow channel plate, the unit cover plate, the cladding plate, and the thin pad plate into a high-pressure side flow channel assembly, wherein edge positioning is performed by laser welding or argon arc welding;

[0021] Step B: placing the high-pressure side flow channel assembly into a diffusion soldering furnace for the first diffusion soldering to obtain a high-pressure side flow channel unit; if there are more than two high-pressure side flow channel assemblies, solder resist is used between adjacent high-pressure side flow channel assemblies;

[0022] Step C: Arranging a low-pressure side spacer on one side of the high-pressure side flow channel unit;

[0023] Welding the thick backing plate to a corresponding position on one side of the high-pressure side flow channel unit;

[0024] A covering strip is provided on one side of the thick pad close to the low-pressure side channel;

[0025] Complete step C to obtain a heat exchange monomer;

[0026] Step D: After stacking and assembling two or more heat exchange units, place them in a diffusion welding furnace for a second diffusion welding to obtain a heat exchanger core unit;

[0027] Step E: welding a high-pressure fluid pipe to the heat exchanger core unit to obtain the microchannel heat exchanger.

[0028] In an optional embodiment, the welding temperature of the first diffusion welding is 1000-1050° C., the holding time is 2-10 hours, the welding pressure is 5-15 MPa, and the welding is cooled with the furnace after completion;

[0029] And / or, the welding temperature of the second diffusion welding is 1000-1050° C., the holding time is 2-10 hours, the welding pressure is 5-15 MPa, and the welding is cooled with the furnace after completion.

[0030] Step A may also include:

[0031] Assembling the cladding plate, the thin pad plate, the thick cover plate, the cladding plate and the thin pad plate into a cover plate unit, wherein edge positioning is performed by laser welding or argon arc welding;

[0032] Assembling the cladding plate, the thin pad plate, the thick bottom plate, the cladding plate and the thin pad plate into a bottom plate unit, wherein edge positioning is performed by laser welding or argon arc welding;

[0033] In step D, the cover plate unit is disposed above the uppermost heat exchange unit, and the bottom plate unit is disposed below the lowermost heat exchange unit.

[0034] In an optional embodiment, a low-pressure side spacer is prepared on one side of the high-pressure side flow channel unit by laser cutting, wire cutting or etching, or the low-pressure side spacer is welded and fixed to a corresponding position of the high-pressure side flow channel unit by spot welding;

[0035] and / or, welding the thick backing plate to a corresponding position on one side of the high-pressure side flow channel unit;

[0036] And / or, the coating strip is welded to the side of the thick pad close to the low-pressure side channel, and the welding method includes one of laser welding, electron beam welding, and argon arc welding; or, the second material is attached to the side of the thick pad close to the low-pressure side channel by laser cladding, electron beam cladding or thermal spraying to form the coating strip, and the thickness of the coating strip is ≥0.3mm.

[0037] The present invention has the following beneficial effects:

[0038] One side of the high- and low-pressure heat exchanger has a higher temperature and pressure (pressure greater than 1MPa), and the other side has a lower pressure (≤1MPa). Due to the different working conditions of the high-pressure side and the low-pressure side, the properties of the fluid passing through are different. Therefore, the high-pressure side and the low-pressure side in this embodiment can adapt to the needs of high-pressure fluid and low-pressure fluid to select materials with different properties, which is conducive to improving the application range of the high- and low-pressure heat exchanger. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0040] Figure 1 It is a structural schematic diagram of a microchannel heat exchanger;

[0041] Figure 2 is a partial cross-sectional view of a microchannel heat exchanger;

[0042] Figure 3 It is a structural schematic diagram of the flow channel plate;

[0043] Figure 4It is a structural schematic diagram of the high-pressure side flow channel unit;

[0044] Figure 5 This is the position relationship diagram of the thick pad;

[0045] Figure 6 It is a structural schematic diagram of a side of a unit cover away from a corresponding high-pressure side microchannel;

[0046] Figure 7 Schematic diagram of the fluid flow direction in the first heat exchange zone;

[0047] Figure 8 is a schematic diagram of the fluid flow direction in the second heat exchange zone;

[0048] Fig. 9 Schematic diagram of the fluid flow direction in the third heat exchange zone;

[0049] Fig.10 This is a schematic diagram of the structure where the cladding plate is located on one side of the low-pressure side channel.

[0050] Illustration: 110-flow channel plate; 120-unit cover plate; 130-high-pressure side microchannel; 140-cladding plate; 210-low-pressure side channel; 150-high-pressure fluid chamber; 160-high-pressure fluid tube; 170-recess; 220-thin pad; 230-thick pad; 240-cladding strip; 250-low-pressure fluid inlet and outlet; 260-low-pressure side partition strip; 261-edge support partition strip; 262-internal support guide partition strip; 263-inlet and outlet guide strip. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0053] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0054] In the description of the present invention, it should be noted that if the terms "upper", "lower", "inside", "outside", etc. appear to indicate an orientation or position relationship, they are based on the orientation or position relationship shown in the accompanying drawings, or are the orientation or position relationship in which the product of the invention is usually placed when used. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0055] In addition, the terms “first”, “second”, etc., if used, are merely used to distinguish between the descriptions and should not be understood as indicating or implying relative importance.

[0056] It should be noted that, in the absence of conflict, the features in the embodiments of the present invention may be combined with each other.

[0057] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0058] The present invention provides a microchannel heat exchanger. Figure 1-4 As shown, it includes high-pressure side flow channel units and low-pressure side flow channel units that are alternately stacked.

[0059] The high-pressure side flow channel unit includes a flow channel plate 110 and a unit cover plate 120 covering one side of the flow channel plate 110, a high-pressure side microchannel 130 for high-pressure fluid to pass through is arranged between the flow channel plate 110 and the unit cover plate 120, and the material of the flow channel plate 110 and the unit cover plate 120 is a first material; a cladding plate 140 is arranged on one side of the flow channel plate 110 away from the unit cover plate 120 and on one side of the unit cover plate 120 away from the flow channel plate 110, and the material of the cladding plate 140 is a second material, and the first material and the second material are different;

[0060] The low-pressure side flow channel unit includes a low-pressure side channel 210 for low-pressure fluid to pass through, and the low-pressure side channel 210 is located between the cladding plates 140 of two adjacent high-pressure side flow channel units.

[0061] One side of the high- and low-pressure heat exchanger has a higher temperature and pressure (pressure greater than 1MPa), and the other side has a lower pressure (≤1MPa). Due to the different working conditions on the high- and low-pressure sides and the different properties of the fluids passing through, materials with different performances need to be selected for the high- and low-pressure sides, which is conducive to improving the application range of the high- and low-pressure heat exchangers.

[0062] The upper and lower surfaces of the high-pressure side flow channel unit are coated with a coating plate 140 of the second material. The thickness of the coating plate 140 is calculated based on the service life of the heat exchanger and the corrosion rate of the material, and the general thickness is between 0.3 mm and 1 mm. The thickness of the two coating plates 140 corresponding to the same high-pressure side flow channel unit can be determined based on the matching of the linear expansion coefficients of the materials to determine whether the thickness of the coating plates 140 on the upper and lower surfaces must be equal, so as to obtain symmetrical stress distribution up and down.

[0063] In some embodiments, if the fluid passing through the low-pressure side is corrosive, the high-pressure side uses austenitic stainless steel with relatively stable welding, and the low-pressure side uses corrosion-resistant materials with specific requirements, such as T91, FeCeAl, high-temperature alloys, etc.

[0064] In some implementations, a microchannel structure is used due to the higher pressure on the high-pressure side; and a large channel structure can be used on the low-pressure side to reduce flow resistance, or even an integral large cavity structure without partitions can be directly used on the low-pressure side.

[0065] In an optional embodiment, if Figure 5 As shown, both ends of the high-pressure side microchannel 130 are provided with high-pressure fluid chambers 150, and both of the two high-pressure fluid chambers 150 are provided with high-pressure fluid pipes 160;

[0066] A partition plate for separating the high-pressure fluid cavity 150 and the low-pressure side channel 210 is arranged between each of the low-pressure side channels 210 and the high-pressure fluid cavity 150, and the partition plate includes a thin pad 220 arranged on the side of the unit cover plate 120 away from the corresponding flow channel plate 110, and a thick pad 230 is also arranged between the thin pads 220 corresponding to two adjacent high-pressure side flow channel units.

[0067] In the embodiment of the present invention, the low-pressure side flow channel unit is formed by enclosing two adjacent high-pressure side flow channel units and a thick pad 230 .

[0068] In an optional embodiment, a coating strip 240 is further provided on one side of the thick pad 230 close to the low-pressure side channel 210 so that the materials in contact with the low-pressure side fluid and the high-pressure side fluid can be set to different materials.

[0069] In an optional embodiment, the material of the component that can contact the high-pressure fluid is a first material, and the material of the component that can contact the low-pressure fluid is a second material.

[0070] According to the requirements of corrosion resistance and strength, all surfaces through which the fluid on the high-pressure side flows are made of the first material, while all surfaces through which the fluid on the low-pressure side flows are made of the second material. The two materials contact their respective fluids respectively to ensure a one-to-one match between the material and the fluid without mixing.

[0071] It should be noted that, considering that the low-pressure side channel 210 may be connected to a pipeline to achieve the inflow and outflow of low-pressure fluid, in some applicable scenarios, it may also be directly immersed in the low-pressure working fluid, and the surface of the heat exchanger may also contact the low-pressure side working fluid, so the outer surface of the heat exchanger can be coated with a second material, and the coating layer thickness is calculated based on the service life of the heat exchanger. The coating layer can be formed by welding the sheet to the corresponding position, or it can be directly prepared on the surface of the heat exchanger by laser cladding or electron beam cladding.

[0072] In some implementations, all high-pressure pressure-bearing welds may be made of austenitic stainless steel welds, which helps ensure product safety.

[0073] In an optional embodiment, if Figure 6 As shown, the flow channel plate 110 and the unit cover plate 120 are both provided with a recessed portion 170 for accommodating the cladding plate 140 , and the difference between the thickness of the cladding plate 140 and the depth of the recessed portion 170 is ≥1 mm.

[0074] The edge of the covering plate 140 protrudes from the flow channel plate 110, which can provide support conditions for subsequent overall covering of the outer side.

[0075] In an optional embodiment, low-pressure fluid cavities communicating with the low-pressure side channel 210 are provided on both sides of each of the high-pressure fluid cavities 150 , and a low-pressure fluid inlet and outlet 250 is provided on each of the low-pressure fluid cavities.

[0076] According to the heat exchange requirements, the low-pressure side cavity can be arranged in one-in-one-out, multiple-in-multiple-out, and the core heat exchange area can be arranged in a co-current, counter-current or cross-current manner, such as Figure 7-9 shown.

[0077] In an optional embodiment, if Fig.10 As shown, the cladding plate 140 is provided with a low-pressure side bulkhead 260 on one side of the low-pressure side channel 210, and the low-pressure side bulkhead 260 includes an edge support bulkhead 261 and an internal support guide bulkhead 262; and / or, the low-pressure side bulkhead 260 includes an inlet and outlet guide bar 263, and the inlet and outlet guide bar 263 is arranged along the low-pressure fluid cavity toward the center of the cladding plate 140.

[0078] In order to close the low-pressure side channel 210, an edge support spacer 261 is set at the edge of the cladding plate 140 so that a channel for the low-pressure fluid to pass through is formed on the low-pressure side; in order to promote sufficient heat exchange between the low-pressure fluid and the high-pressure fluid, internal support guide spacers 262 and inlet and outlet guide strips 263 are also set, which can guide the direction of the fluid on the one hand, and support the low-pressure side channel 210 on the other hand, which is beneficial to improving the stability of the heat exchanger.

[0079] The present invention also provides a method for manufacturing the microchannel heat exchanger described in the above embodiment, comprising:

[0080] Step A: Assemble the cladding plate 140, the thin pad plate 220, the flow channel plate 110, the unit cover plate 120, the cladding plate 140, and the thin pad plate 220 into a high-pressure side flow channel assembly, wherein laser welding or argon arc welding is used for edge positioning;

[0081] Step B: placing the high-pressure side flow channel assembly into a diffusion soldering furnace for the first diffusion soldering to obtain a high-pressure side flow channel unit; if there are more than two high-pressure side flow channel assemblies, solder resist is used between adjacent high-pressure side flow channel assemblies;

[0082] Step C: Disposing a low-pressure side partition bar 260 on one side of the high-pressure side flow channel unit;

[0083] Welding the thick pad 230 to a corresponding position on one side of the high-pressure side flow channel unit;

[0084] A covering strip 240 is provided on one side of the thick pad 230 close to the low-pressure side channel 210;

[0085] Complete step C to obtain a heat exchange monomer;

[0086] Step D: After stacking and assembling two or more heat exchange units, place them in a diffusion welding furnace for a second diffusion welding to obtain a heat exchanger core unit;

[0087] Step E: welding the high-pressure fluid pipe 160 to the heat exchanger core unit, and the welding method may be argon arc welding to obtain the microchannel heat exchanger.

[0088] In the embodiment of the present invention, the first diffusion welding is performed to obtain the high-pressure side flow channel unit, and the second diffusion welding is performed to obtain the heat exchanger core unit. The use of two diffusion welding methods is beneficial to improving the strength of the welding position, thereby increasing the service life of the heat exchanger.

[0089] The solder resist used in diffusion welding can be mica or ceramic. After diffusion welding is completed, the solder resist on the welding surface can be removed by physical means, and then the surface of the unit board is processed to obtain a clean heat exchange surface for standby use. Surface processing can be carried out by milling or grinding. The surface roughness of the area requiring secondary welding is ≤0.8μm, and the non-welding area is ≤6.3μm.

[0090] The welded high-pressure side flow channel unit is tested by helium mass spectrometry and is put into use after being confirmed to meet the technical requirements. The obtained microchannel heat exchanger can be subjected to a pressure test according to the design requirements of the heat exchanger, and after the test, it is dried, cleaned and packaged for use.

[0091] It should be noted that in the embodiments of the present application, the heat exchanger core units can be used in series or parallel as needed.

[0092] In some embodiments, the high-pressure side flow channel plate 110 is obtained by chemical etching or mechanical processing, and the unit cover plate 120, the cladding plate 140, and the thin pad 220 are obtained by wire cutting or laser cutting. The cladding plate 140 and the thin pad 220 have the same thickness or are calculated based on the difference in linear expansion coefficients of the two metals (height difference = linear expansion coefficient difference * welding temperature * thickness of the cladding plate 140), ensuring that the surfaces of the two are flush during diffusion welding. In some embodiments, the high-pressure side flow channel plate 110, the cover plate, and the thin pad 220 are made of 316LN stainless steel, and the cladding plate 140 is made of T91 steel.

[0093] In an optional embodiment, the welding temperature of the first diffusion welding is 1000-1050° C., the holding time is 2-10 hours, the welding pressure is 5-15 MPa, and the welding is cooled with the furnace after completion;

[0094] And / or, the welding temperature of the second diffusion welding is 1000-1050° C., the holding time is 2-10 hours, the welding pressure is 5-15 MPa, and the welding is cooled with the furnace after completion.

[0095] In an optional embodiment, among the two or more heat exchange units, the cover plate thickness corresponding to the topmost heat exchange unit is greater than the cover plate thickness in other heat exchange units, and the flow channel plate 110 thickness corresponding to the bottommost heat exchange unit is greater than the flow channel plate 110 thickness in other heat exchange units.

[0096] In an optional embodiment, step A may further include:

[0097] Assemble the cladding plate 140, the thin pad plate 220, the thick cover plate, the cladding plate 140, and the thin pad plate 220 into a cover plate unit, wherein edge positioning is performed by laser welding or argon arc welding;

[0098] Assemble the cladding plate 140, the thin pad plate 220, the thick bottom plate, the cladding plate 140, and the thin pad plate 220 into a bottom plate unit, wherein edge positioning is performed by laser welding or argon arc welding;

[0099] In step D, the cover plate unit is disposed above the uppermost heat exchange unit, and the bottom plate unit is disposed below the lowermost heat exchange unit.

[0100] In an optional embodiment, the low-pressure side spacer 260 is prepared on one side of the high-pressure side flow channel unit by laser cutting, wire cutting or etching, or the low-pressure side spacer 260 is welded and fixed to the corresponding position of the high-pressure side flow channel unit by spot welding. When fixing, the sealing gap between the low-pressure side spacer 260 and the unit plate is required to be less than or equal to 0.1 mm.

[0101] In an optional embodiment, the thick pad 230 is welded to a corresponding position on one side of the high-pressure side flow channel unit, and when fixing, the sealing gap between the low-pressure side spacer 260 and the unit plate is required to be less than or equal to 0.1 mm.

[0102] In an optional embodiment, the coating strip 240 is welded to the side of the thick pad 230 close to the low-pressure side channel 210, and the welding method includes one of laser welding, electron beam welding, and argon arc welding; or, the second material is attached to the side of the thick pad 230 close to the low-pressure side channel 210 by laser cladding, electron beam cladding or thermal spraying to form the coating strip 240, and the thickness of the coating strip 240 is ≥0.3 mm.

[0103] The thick pad 230 has the same thickness as the low-pressure side spacer 260 and the cladding strip 240 or is calculated based on the difference in linear expansion coefficients of the two metals (height difference = linear expansion coefficient difference * welding temperature * thickness of cladding plate 140 ), ensuring the same total height during diffusion welding.

[0104] After two or more heat exchange units are stacked and assembled, the heat exchanger core is pre-tightened with a hydraulic press and pre-tightened by welding on the side walls before being loaded into a diffusion welding furnace.

[0105] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A microchannel heat exchanger, characterized in that: It includes high-pressure side flow channel units and low-pressure side flow channel units that are alternately stacked. The high-pressure side flow channel unit comprises a flow channel plate and a unit cover plate covering one side of the flow channel plate, a high-pressure side microchannel for high-pressure fluid to pass through is arranged between the flow channel plate and the unit cover plate, and the material of the flow channel plate and the unit cover plate is a first material; a coating plate is arranged on one side of the flow channel plate away from the unit cover plate and on one side of the unit cover plate away from the flow channel plate, and the material of the coating plate is a second material, and the first material and the second material are different; The low-pressure side flow channel unit comprises a low-pressure side channel for low-pressure fluid to pass through, and the low-pressure side channel is located between the cladding plates of two adjacent high-pressure side flow channel units.

2. The microchannel heat exchanger according to claim 1, characterized in that: Both ends of the high-pressure side microchannel are provided with high-pressure fluid cavities, and both of the two high-pressure fluid cavities are provided with high-pressure fluid pipes; A partition plate for separating the high-pressure fluid cavity and the low-pressure side channel is arranged between each of the low-pressure side channels and the high-pressure fluid cavity. The partition plate includes a thin pad arranged on the side of the unit cover plate away from the corresponding flow channel plate, and a thick pad is also arranged between the thin pads corresponding to two adjacent high-pressure side flow channel units.

3. The microchannel heat exchanger according to claim 2, characterized in that: A coating strip is also provided on one side of the thick pad close to the low-pressure side channel; And / or, the material of the component that can contact the high-pressure fluid is a first material, and the material of the component that can contact the low-pressure fluid is a second material.

4. The microchannel heat exchanger according to claim 1, characterized in that: The flow channel plate and the unit cover plate are both provided with a concave portion for accommodating the cladding plate, and the difference between the thickness of the cladding plate and the depth of the concave portion is ≥1 mm.

5. The microchannel heat exchanger according to claim 1, characterized in that: Low-pressure fluid cavities communicating with the low-pressure side channels are arranged on both sides of each of the high-pressure fluid cavities, and a low-pressure fluid inlet and outlet is arranged on each of the low-pressure fluid cavities.

6. The microchannel heat exchanger according to claim 1, characterized in that: The cladding plate is provided with a low-pressure side partition bar on one side of the low-pressure side channel, and the low-pressure side partition bar includes an edge support partition bar and an internal support guide partition bar; and / or the low-pressure side partition bar includes an inlet and outlet guide bar, and the inlet and outlet guide bars are arranged along the low-pressure fluid cavity toward the center of the cladding plate.

7. A method for manufacturing a microchannel heat exchanger according to any one of claims 1 to 6, characterized in that: include: Step A: Assembling the cladding plate, the thin pad plate, the flow channel plate, the unit cover plate, the cladding plate, and the thin pad plate into a high-pressure side flow channel assembly, wherein edge positioning is performed by laser welding or argon arc welding; Step B: placing the high-pressure side flow channel assembly into a diffusion soldering furnace for the first diffusion soldering to obtain a high-pressure side flow channel unit; if there are more than two high-pressure side flow channel assemblies, solder resist is used between adjacent high-pressure side flow channel assemblies; Step C: Arranging a low-pressure side spacer on one side of the high-pressure side flow channel unit; Welding the thick backing plate to a corresponding position on one side of the high-pressure side flow channel unit; A covering strip is provided on one side of the thick pad close to the low-pressure side channel; Complete step C to obtain a heat exchange monomer; Step D: After stacking and assembling two or more heat exchange units, place them in a diffusion welding furnace for a second diffusion welding to obtain a heat exchanger core unit; Step E: welding a high-pressure fluid pipe to the heat exchanger core unit to obtain the microchannel heat exchanger.

8. The method for manufacturing a microchannel heat exchanger according to claim 7, characterized in that: The welding temperature of the first diffusion welding is 1000-1050℃, the holding time is 2-10h, the welding pressure is 5-15MPa, and the furnace is cooled after welding. And / or, the welding temperature of the second diffusion welding is 1000-1050° C., the holding time is 2-10 hours, the welding pressure is 5-15 MPa, and the welding is cooled with the furnace after completion.

9. The method for manufacturing a microchannel heat exchanger according to claim 7, characterized in that: Step A may also include: Assembling the cladding plate, the thin pad plate, the thick cover plate, the cladding plate and the thin pad plate into a cover plate unit, wherein edge positioning is performed by laser welding or argon arc welding; Assembling the cladding plate, the thin pad plate, the thick bottom plate, the cladding plate and the thin pad plate into a bottom plate unit, wherein edge positioning is performed by laser welding or argon arc welding; In step D, the cover plate unit is disposed above the uppermost heat exchange unit, and the bottom plate unit is disposed below the lowermost heat exchange unit.

10. The method for manufacturing a microchannel heat exchanger according to claim 9, characterized in that: A low-pressure side spacer is prepared on one side of the high-pressure side flow channel unit by laser cutting, wire cutting or etching, or the low-pressure side spacer is welded and fixed to the corresponding position of the high-pressure side flow channel unit by spot welding; and / or, welding the thick backing plate to a corresponding position on one side of the high-pressure side flow channel unit; And / or, the coating strip is welded to the side of the thick pad close to the low-pressure side channel, and the welding method includes one of laser welding, electron beam welding, and argon arc welding; or, the second material is attached to the side of the thick pad close to the low-pressure side channel by laser cladding, electron beam cladding or thermal spraying to form the coating strip, and the thickness of the coating strip is ≥0.3mm.

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