Manufacturing method for heat exchanger and heat exchanger

Abstract

A manufacturing method for a heat exchanger (10) and the heat exchanger (10). The manufacturing method for the heat exchanger (10) comprises the following steps: assembling heat exchange tubes (1) and first tubes (2), comprising connecting the heat exchange tubes (1) and the first tubes (2), wherein the heat exchange tubes (1) are made of stainless steel, and the first tubes (2) are made of stainless steel; welding the heat exchange tubes (1) and the first tubes (2); assembling fins (4) and the heat exchange tubes (1), comprising mounting at least part of each fin (4) between adjacent heat exchange tubes (1), wherein the fins (4) are made of aluminum or an aluminum alloy; welding the heat exchange tubes (1) and the fins (4). Before the heat exchange tubes (1) and the fins (4) are assembled, an aluminum material or a nickel material is applied onto at least a portion of the surface of each heat exchange tube (1) to form a coating (3).

Description

Heat exchanger processing method and heat exchanger

[0001] Cross-reference to related applications

[0002] The present disclosure is based on and claims priority to Chinese Patent Application No. 202411015170.7, filed on July 24, 2024, and Chinese Patent Application No. 202510763731.X, filed on June 6, 2025, the contents of which are hereby incorporated by reference in their entirety. TECHNICAL FIELD

[0003] The present application relates to the technical field of heat exchangers, and in particular to a heat exchanger processing method including a stainless steel tube and a heat exchanger. BACKGROUND

[0004] At present, heat exchangers have been widely used in heat exchange system fields. In the related art, when the heat exchange tube is connected with the fin, the connection is achieved by tube expansion. When the tube is expanded, the thermal resistance between the heat exchange tube and the fin is large, which affects the heat exchange efficiency of the heat exchanger. On the other hand, in order to improve the corrosion resistance of the heat exchanger, the heat exchange tube can be made of stainless steel. After the material of the heat exchange tube changes, the different components of the heat exchanger will have poor welding when they are welded, which affects the reliability of the heat exchanger. SUMMARY

[0005] The present application provides a heat exchanger processing method, which improves the welding reliability and the reliability of the heat exchanger, and the heat exchanger has good corrosion resistance.

[0006] The present application provides a heat exchanger, which is beneficial to improve the corrosion resistance and heat exchange performance of the heat exchanger.

[0007] According to the embodiments of the first aspect of the present application, a heat exchanger processing method is provided, which includes the following steps:

[0008] Assembling the heat exchange tube and the first tube includes connecting the heat exchange tube and the first tube, the material of the heat exchange tube is stainless steel, and the material of the first tube is stainless steel;

[0009] Welding the connection between the heat exchange tube and the first tube;

[0010] Assembling the fin and the heat exchange tube includes mounting at least part of the fin between adjacent heat exchange tubes, and the material of the fin is aluminum or aluminum alloy;

[0011] Welding the heat exchange tube and the fin;

[0012] Wherein, before assembling the heat exchange pipe and the fin, an aluminum material or a nickel material is arranged on at least a part of the surface of the heat exchange pipe to form a coating.

[0013] The heat exchanger processing method of the embodiment of the present application realizes welding of the heat exchanger by welding the stainless steel heat exchange pipe and the stainless steel first pipe and welding the stainless steel heat exchange pipe and the aluminum fin. Before welding the heat exchange pipe and the fin, the aluminum material or the nickel material is plated on at least a part of the surface of the heat exchange pipe to form a coating, which reduces the generation of brittle metal compounds at the welding position when the stainless steel heat exchange pipe and the aluminum fin are welded, reduces the risk of leakage of the heat exchanger, improves the welding reliability, and improves the reliability of the heat exchanger. Moreover, the heat exchanger uses the stainless steel heat exchange pipe and the stainless steel first pipe, and has good corrosion resistance, thereby improving the service life of the heat exchanger.

[0014] According to the embodiment of the second aspect of the present application, a heat exchanger is provided, comprising:

[0015] A plurality of heat exchange pipes, the material of the heat exchange pipes being stainless steel;

[0016] A first pipe, the material of the first pipe being stainless steel; the first pipe is connected with the heat exchange pipes, and the inner cavity of the first pipe is in communication with the inner cavities of the heat exchange pipes;

[0017] A fin, at least a part of the fin being welded between two adjacent heat exchange pipes, and the material of the fin being aluminum or aluminum alloy.

[0018] The heat exchanger of the embodiment of the present application uses stainless steel for the heat exchange pipes and the first pipe, thereby improving the corrosion resistance of the heat exchanger, reducing the risk of leakage due to corrosion, and improving the service life of the heat exchanger. The fin is made of aluminum, which improves the heat exchange performance of the heat exchanger. The heat exchange pipes and the fin are connected by welding, which reduces the contact thermal resistance of the heat exchange pipes and the fin, and further improves the heat exchange performance of the heat exchanger.

[0019] The additional aspects and advantages of the present application will be partially given in the following description, partially will become obvious from the following description, or will be understood by the practice of the present application. BRIEF DESCRIPTION OF DRAWINGS

[0020] The above and / or additional aspects and advantages of the present application will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings, in which:

[0021] FIG. 1 is a structural schematic diagram of a heat exchanger according to one embodiment of the present application;

[0022] FIG. 2 is a perspective structural schematic diagram of a heat exchanger according to one embodiment of the present application;

[0023] Fig. 3 is a structural schematic diagram of a heat exchanger according to another embodiment of the present application;

[0024] Fig. 4 is a structural schematic diagram of a heat exchanger according to yet another embodiment of the present application;

[0025] Fig. 5 is a partial structural schematic diagram of the heat exchanger in Fig. 3 or Fig. 4;

[0026] Fig. 6 is a partial structural schematic diagram of a heat exchanger according to yet another embodiment of the present application;

[0027] Fig. 7 is a schematic diagram of a turbulence structure arranged in a heat exchange tube of a heat exchanger according to an embodiment of the present application;

[0028] Fig. 8 is a schematic diagram of a coating on an outer surface of a heat exchange tube according to an embodiment of the present application;

[0029] Fig. 9 is a partial structural schematic diagram of an embodiment at position A in Fig. 1;

[0030] Fig. 10 is a partial structural schematic diagram of another embodiment at position A in Fig. 1;

[0031] Reference signs: 10, heat exchanger; 1, heat exchange tube; 2, first tube; 3, coating; 4, fin; 5, turbulence structure; 6, welding portion. DETAILED DESCRIPTION

[0032] Embodiments of the present application are described in detail below. The embodiments described below with reference to the drawings are exemplary and are only used to explain the present application and cannot be understood as a limitation of the present application.

[0033] In the related art, copper materials and aluminum materials are widely used in heat exchangers due to good processing and heat conduction performance, such as a typical copper tube aluminum fin expanded heat exchanger. However, due to the limitation of copper ore resources, improvements for heat exchangers are imminent. Currently, "aluminum instead of copper" has a high cost performance on heat exchangers, but aluminum materials are highly active and cannot well meet the requirements of corrosion resistance and service life of heat exchanger products when used in some highly corrosive environments. From the corrosion resistance of the material, stainless steel material has more advantages, but when stainless steel tubes are used to replace copper or aluminum tubes for heat exchangers, the heat exchangers of different materials will have poor welding problems when welding, which will cause the heat exchanger to leak and affect the reliability of the heat exchanger. At the same time, in the related art, the heat exchange tube and the fin are connected by expanding the tube to achieve connection, which causes the thermal resistance between the heat exchange tube and the fin to be large, affecting the heat exchange efficiency of the heat exchanger.

[0034] Based on this, the technical scheme of the embodiment of the present application provides a heat exchanger processing method and a heat exchanger. For the heat exchanger processing method, the present application provides a method for welding a heat exchanger, realizes the welding of the heat exchanger, improves the welding reliability and the reliability of the heat exchanger, and the heat exchanger has good corrosion resistance. The heat exchanger provided by the technical method of the embodiment of the present application is made of stainless steel for the heat exchange tube and the first tube, and made of aluminum for the fin. The heat exchange tube and the fin are combined by welding, thereby improving the heat exchange performance of the heat exchanger. The specific technical scheme is described below.

[0035] To achieve the above-mentioned purpose, the first aspect of the present application provides a heat exchanger processing method, comprising the following steps:

[0036] Assembling the heat exchange tube and the first tube includes connecting the heat exchange tube and the first tube; the material of the heat exchange tube is stainless steel, and the material of the first tube is stainless steel; welding the connection part of the heat exchange tube and the first tube; assembling the fin and the heat exchange tube includes mounting at least part of the fin between adjacent heat exchange tubes, and the material of the fin is pure aluminum or aluminum alloy; welding the heat exchange tube and the fin; wherein, before assembling the heat exchange tube and the fin, an aluminum material or a nickel material is arranged on at least part of the surface of the heat exchange tube to form a coating.

[0037] The heat exchanger with different materials can be used for water system and air heat exchange, and can also be used for refrigerant and air heat exchange. The heat exchanger can circulate water, refrigerant and other heat exchange media, and can be obtained by the following steps.

[0038] Step S11: Assembling the heat exchange tube and the first tube includes connecting the heat exchange tube and the first tube; the material of the heat exchange tube is stainless steel, and the material of the first tube is stainless steel.

[0039] Step S21: Welding the heat exchange tube and the first tube.

[0040] Step S31: Assembling the fin and the heat exchange tube includes mounting at least part of the fin between adjacent heat exchange tubes, and the material of the fin is pure aluminum or aluminum alloy.

[0041] Step S41: Welding the heat exchange tube and the fin.

[0042] Wherein, before welding the heat exchange tube and the fin, an aluminum material or a nickel material is arranged on at least part of the surface of the heat exchange tube to form a coating.

[0043] Wherein, two-step welding method is adopted in the present application, that is, welding the stainless steel first pipe 2 and the stainless steel heat exchange pipe 1, and welding the stainless steel heat exchange pipe 1 and the aluminum fin 4. The first pipe 2 and the heat exchange pipe 1 are welded into one whole to realize the sealing between the welding and the connecting position of the first pipe 2 and the heat exchange pipe 1. The heat exchange pipe 1 and the fin 4 are welded into one whole to realize the reliability between the heat exchange pipe 1 and the fin 4, reduce the thermal resistance between the heat exchange pipe 1 and the fin 4, and improve the heat exchange effect. The two-step welding has no sequence limitation. The first pipe 2 and the heat exchange pipe 1 and the heat exchange pipe 1 and the fin 4 are welded respectively, so that the joints of the heat exchanger with different materials at the connecting position of the first pipe 2 and the heat exchange pipe 1 and at the connecting position of the heat exchange pipe 1 and the fin 4 are welded well, the welding reliability is improved, the risk of leakage of the heat exchanger is reduced, and the service life of the heat exchanger is improved. Moreover, the heat exchanger using the processing method has good corrosion resistance due to the use of the stainless steel heat exchange pipe 1 and the stainless steel first pipe 2, and the service life of the heat exchanger is improved.

[0044] The stainless steel heat exchange pipe 1 and the aluminum fin 4 can be brazed by using aluminum-silicon-based filler metal when welding. Since the heat exchange pipe 1 and the fin 4 are metals with different materials, a continuous brittle intermetallic compound layer such as iron-aluminum compound is often formed in the weld on one side of the heat exchange pipe 1, so that the weld at the welding position of the heat exchange pipe 1 and the fin 4 is brittle, and there is a risk of cracking and falling under the action of temperature and pressure changes in the subsequent use of the heat exchanger 10. To reduce the risk, at least a part of the surface of the stainless steel heat exchange pipe 1 is coated with aluminum or nickel material to form a coating before being welded with the fin 4, which can reduce the formation of a continuous brittle intermetallic compound in the weld on one side of the heat exchange pipe 1, wherein the intermetallic compound is an iron-aluminum compound layer, to improve the welding reliability of the heat exchange pipe 1 and the fin, improve the service life of the weld between the heat exchange pipe 1 and the fin 4, reduce the risk of leakage of the heat exchanger, and further improve the reliability of the heat exchanger 10 and the service life of the heat exchanger 10. Wherein, the aluminum material is pure aluminum or aluminum alloy, and the nickel material is pure nickel or nickel alloy.

[0045] When the heat exchange tube 1 made of stainless steel is welded with the fin 4 after the surface of at least a part of the heat exchange tube 1 is coated with aluminum material to form a coating, the welding between the heat exchange tube 1 and the fin 4 is aluminum and aluminum welding, which reduces the formation of brittle intermetallic compounds in the weld of the heat exchange tube 1, improves the welding reliability of the heat exchange tube 1 and the fin 4, reduces the risk of leakage of the heat exchanger, and thus improves the reliability and service life of the heat exchanger 10. When the heat exchange tube 1 made of stainless steel is welded with the fin 4 after the surface of at least a part of the heat exchange tube 1 is coated with nickel material to form a coating, the joint formed by the metallurgical reaction between the aluminum-silicon-based filler metal and the nickel coating is much less brittle than the joint formed by the metallurgical reaction between the aluminum-silicon-based filler metal and the stainless steel, which reduces the formation of brittle intermetallic compounds in the weld of the heat exchange tube 1, improves the welding reliability of the heat exchange tube 1 and the fin, reduces the risk of leakage, and thus improves the reliability and service life of the heat exchanger 10.

[0046] Therefore, the present application is welded by the first tube 2 and the heat exchange tube 1 and the heat exchange tube 1 and the fin 4 respectively, and before welding the heat exchange tube and the fin, aluminum material or nickel material is coated on at least a part of the outer surface of the heat exchange tube to form a coating, which improves the reliability of the overall heat exchanger, reduces the problem of poor welding of various components of different materials of the heat exchanger when welding, reduces the risk of leakage of the heat exchanger, and improves the reliability of the heat exchanger. At the same time, the heat exchanger has good corrosion resistance.

[0047] The steps of the processing method are described in detail below. In step S11, the heat exchange tube and the first tube can be a round tube, an oval tube, a flat tube, etc. The first tube 2 is used to connect multiple heat exchange tubes 1. The first tube 2 can be a manifold structure as shown in FIGS. 1, 2 and 4, or a bent pipe structure as shown in FIG. 3.

[0048] The material of the heat exchange tube 1 is stainless steel, and the material of the first tube 2 is stainless steel. In the working state of the heat exchanger 10, the heat exchange tube and the first tube 2 are in communication, and the heat exchange medium such as water, refrigerant, etc. flows in the tube. If the heat exchange tube 1 or the first tube 2 leaks, it will affect the service life of the heat exchanger. Therefore, the heat exchange tube 1 and the first tube 2 are made of stainless steel, which can improve the corrosion resistance of the heat exchanger 10 and prolong the service life of the heat exchanger 10.

[0049] The step of assembling the heat exchange pipe 1 and the first pipe 2 specifically comprises that, as shown in FIG. 2 or FIG. 4, the end of the plurality of heat exchange pipes 1 is inserted into the first pipe 2, the first pipe 2 is 2, the two ends of the heat exchange pipe 1 are inserted into the first pipe 2 respectively, the plurality of heat exchange pipes 1 are communicated with the first pipe 2, the end of the first pipe 2 can be provided with an end cover, the sealing of the end of the first pipe is realized through the end cover, the first pipe 2 can be provided with an interface of an inlet and outlet pipe for the flow of the heat exchange medium, the first pipe 2 can be provided with a partition plate, and in addition, the first pipe 2 can be additionally provided with a mounting bracket and other components, wherein the materials of the end cover, the inlet and outlet pipe, the partition plate, the mounting bracket and other pipe assemblies are all stainless steel materials. As shown in FIG. 3, the end of the different heat exchange pipes 1 is inserted into the first pipe 2, the first pipe 2 is a bent pipe structure, and the plurality of heat exchange pipes 1 are communicated through the bent pipe, wherein the bent pipe is a U-shaped pipe.

[0050] In step S21, the connection of the heat exchange pipe 1 and the first pipe 2 or the connection of the first pipe 2 and other pipe assembly parts is mainly completed, which is realized through the following steps. The heat exchange pipe 1 and the first pipe 2 in the heat exchanger 10 shown in FIG. 2 or FIG. 4 are assembled as required, and the assembly can also include other pipe assemblies connected with the first pipe 2, such as an end cover, an inlet and outlet pipe, a partition plate, a mounting bracket and the like. In the assembly process, brazing materials can be placed in the gaps between different components, and if necessary, spot welding can be performed at the connection of different components. The heat exchange pipe 1 and the first pipe 2 in the heat exchanger 10 shown in FIG. 3 are assembled as required, and in the assembly process, brazing materials can be placed in the gaps between different components, and if necessary, spot welding can be performed at the connection of different components.

[0051] Moreover, the assembled heat exchanger structure is placed on a heat-resistant tooling with fixing and supporting functions, and the assembled structure is placed in a heating furnace together with the heat-resistant tooling. The structure is heated, kept warm and cooled according to the set program, and the brazing connection and sealing of the stainless steel parts including the heat exchange pipe 1 and the first pipe 2 are completed.

[0052] In the process of welding the heat exchange pipe 1 and the first pipe 2 in step S21, nickel-based filler metal is used for vacuum brazing of the heat exchange pipe 1 and the first pipe 2; or manganese-based filler metal or high-copper filler metal or silver self-brazing filler metal is used as the solder for brazing the heat exchange pipe 1 and the first pipe 2 in gas protection; or nickel-based filler metal or silver filler metal is used as the solder to cooperate with borate fluoride brazing flux for induction brazing or flame brazing of the heat exchange pipe 1 and the first pipe 2.

[0053] When the heat exchange pipe 1 and the first pipe 2 are brazed by using nickel-based filler metal as the solder, the nickel-based filler metal includes BNi82CrSiB, BNi71CrSi and BNi76CrP. The melting points of the three kinds of nickel-based filler metals are different, and the brittleness is slightly different.

[0054] In the step of welding the heat exchange tube 1 and the first tube 2, the gap at the joint of the heat exchange tube 1 and the first tube 2 is controlled to be in the range of 0.03-0.25 mm. The gap is mainly located at the joint of the outer periphery of the heat exchange tube 1 inserted into the first tube and the first tube, and is the gap at the joint of the heat exchange tube 1 and the first tube which needs to be welded and combined. The gap is controlled to be in the range of 0.03-0.25 mm to reduce the problems that the leakage may be caused by the too small or too large gap which may cause the solder to be unable to fill the welding seam or the welding seam to be too brittle and the joint strength to be low.

[0055] In some embodiments, when the nickel-based solder is used for brazing, the gap at the joint of the heat exchange tube 1 and the first tube is controlled to be in the range of 0.03-0.08 mm. In the case that the gap is less than 0.03 mm, the leakage may be caused by the solder being unable to fill the welding seam, the welding being not firm and the joint strength being low. In the case that the gap is too large, for example, greater than 0.08 mm, the leakage may be caused by the solder being unable to fill the welding seam or the welding seam being too brittle and the joint strength being low, which results in the joint of the heat exchange tube 1 and the first tube being formed by a false welding and affects the welding reliability of the heat exchange tube 1 and the first tube.

[0056] In some embodiments, when the manganese-based solder or high-copper solder or silver self-brazing solder or silver solder is used for brazing, the gap at the joint of the heat exchange tube 1 and the first tube is controlled to be in the range of 0.03-0.25 mm. The concentration of the manganese-based solder or high-copper solder or silver self-brazing solder or silver solder is relatively large compared with the concentration of the nickel-based solder, and the gap at the joint can be slightly large. In the case that the gap at the joint is greater than 0.25 mm, the leakage may be caused by the solder being unable to fill the welding seam or the welding seam being too brittle and the joint strength being low, which results in the joint of the heat exchange tube 1 and the first tube being formed by a false welding and affects the welding reliability of the heat exchange tube 1 and the first tube.

[0057] In some embodiments, when the gap at the joint of the heat exchange tube 1 and the first tube 2 is controlled, the volume of the solder in the gap at the joint is also controlled to be 2-5 times the volume of the gap, that is, the circumferential solder paste coating amount of the heat exchange tube 1 at the joint with the first tube 2 is controlled to be 2-5 times the theoretical volume of the welding seam. Thus, the molten solder can sufficiently fill the gap at the joint of the heat exchange tube 1 and the first tube 2, and the reliability of the welding joint of the heat exchange tube 1 and the first tube 2 is improved.

[0058] In some embodiments, the nickel-based solder at the joint of the partial stainless steel can also use the nickel-based solder tape or amorphous foil, for example, the welding seam between the heat exchange tube 1 and the first tube 2 or the welding seam between the mounting bracket and the first tube 2. The preformed tape or preformed foil can be placed between the heat exchange tube 1 and the first tube 2 or between the mounting bracket and the first tube 2, and then the heat exchange tube 1, the first tube 2 and the mounting bracket are fixed together and then welded.

[0059] Since the material of the brazing seam and the material of the stainless steel pipe are not the same, the brazed joint of the stainless steel pipe can become a weak link of corrosion. In some embodiments, a nickel-based filler material that is better in corrosion resistance and has better corrosion matching with stainless steel can be selected. The corrosion resistance of the nickel-based filler material in some heat exchangers 10 in applications where the water quality is not controllable is better than that of a copper brazing filler metal brazed stainless steel pipe.

[0060] In some embodiments, the welded connection and sealing of the heat exchange pipe 1 and the stainless steel part of the first pipe 2 can also be brazed in a gas protection using a manganese-based filler metal. The manganese-based filler metal can be used for brazing of stainless steel. The manganese-based filler metal is mainly used for brazing in an argon protection furnace and induction brazing and low vacuum brazing, such as BMn70NiCr, which can be used to braze stainless steel structures at 1150-1180°C for a certain time, such as 10 minutes, under argon protection.

[0061] In some embodiments, the welded connection and sealing of the heat exchange pipe 1 and the stainless steel part of the first pipe 2 can also be brazed in a gas protection using a high-copper filler metal as the solder. High-temperature copper filler metal is mostly based on Cu-Mn and Cu-Ni with the addition of other alloying elements. The high-temperature strength of this filler metal is higher than that of conventional silver filler metal, and can meet the requirement of working temperature of 400-600°C.

[0062] In some embodiments, the welded connection and sealing of the heat exchange pipe 1 and the stainless steel part of the first pipe can also be brazed in a gas protection using a silver self-brazing filler metal as the solder. The melting temperature of the silver filler metal mostly falls between 600-900°C; the silver self-brazing filler metal has a certain moisture absorption when matched with borate fluoride flux, and the joint needs to be cleaned after welding; the silver content of the silver self-brazing filler metal is higher than that of conventional silver filler metal, and the price is also higher.

[0063] In some embodiments, the welded connection of the heat exchange pipe 1 and the stainless steel part of the first pipe can also be induction brazed or flame brazed using a nickel-based filler metal or a silver filler metal as the solder matched with a borate fluoride flux, which is more convenient to process.

[0064] In some embodiments, in the step of brazing the heat exchange pipe 1 and the first pipe 2 by vacuum brazing or by gas protection brazing, the temperature out of the furnace is controlled to be less than or equal to 200°C.

[0065] In the above content, the assembled heat exchange pipe 1 and the first pipe 2 are placed in a heating furnace together with heat-resistant tools, and the structure is heated, soaked and cooled according to the set program. In this process, vacuum brazing can be selected to keep the stainless steel heat exchange pipe 1 and the stainless steel first pipe 2 clean, which is beneficial to the subsequent welding process and improves the reliability of the heat exchanger 10.

[0066] In some embodiments, in order to ensure the surface of the stainless steel heat exchange tube and the stainless steel first tube is clean after the welding process, the temperature at which the heat exchange tube 1 and the first tube 2 are welded by vacuum brazing or by gas shielded brazing is controlled to be less than or equal to 200°C. If the temperature at which the heat exchange tube 1 and the first tube 2 are welded is too high, for example, higher than 200°C, the stainless steel can be oxidized and discolored, which can affect the welding effect of the heat exchange tube 1 and other components.

[0067] In some embodiments, after the heat exchange tube 1 and the first tube 2 are welded, a high-temperature diffusion treatment after brazing is performed.

[0068] In some embodiments, in order to improve the performance of the welded joint of the heat exchange tube 1 and the first tube 2 or to increase the upper limit of the brazing gap, a high-temperature diffusion treatment after brazing can be performed after the heat exchange tube 1 and the first tube 2 are welded by vacuum brazing or by gas shielded brazing or by induction brazing or by flame brazing. In other words, the assembled structure described above is placed in a heating furnace together with heat-resistant fixtures, and the structure is heated, held, and cooled according to a set program. The high-temperature diffusion treatment after brazing is performed for a set time when the temperature is cooled to a set temperature. For example, the vacuum degree of the heating furnace body during the brazing process is better than 10 -2 Pa, the heating rate is 15°C / min-20°C / min, the brazing temperature is set to 1000-1170°C, and the holding time at the brazing temperature is 10 min-15 min. The high-temperature diffusion treatment after brazing is performed for a set time, for example, 1 h, when the temperature is cooled to a set temperature, for example, 1000°C. The brazing connection and sealing of the stainless steel parts, including the heat exchange tube 1 and the first tube 2, are completed. Nickel-based filler metal is used for brazing, and after brazing, the high-temperature diffusion treatment is performed. The elements such as boron, silicon, and sulfur at the joint of the stainless steel heat exchange tube and the first tube diffuse into the stainless steel base material, so that the strength of the joint is higher and the pressure resistance is improved.

[0069] In some embodiments, the welding and sealing of the heat exchange tube 1 and the first tube 2 and other stainless steel parts can also be performed by fusion welding, which includes laser welding the heat exchange tube 1 and the first tube 2 or arc welding the heat exchange tube 1 and the first tube 2. By using fusion welding, the heat exchange tube 1 and the first tube 2 can be partially welded, which improves the flexibility of heat exchanger processing and has high welding reliability.

[0070] In some embodiments, after the heat exchange tube 1 and the first tube 2 are welded, a gas tightness test is performed.

[0071] Wherein, the stainless steel part of the heat exchanger 10 completed in the above step S11 and step S21 is subjected to air tightness detection, and after passing the detection, the next process is entered to assemble and braze the heat exchange tube 1 and the fin 4. Wherein, the air tightness detection can be carried out by helium detection. In the working state of the heat exchanger 10, the heat exchange tube 1 and the first tube are in flow communication with the heat exchange medium, and in the case of poor air tightness of the heat exchange tube 1 or the first tube, the heat exchange medium will leak. The air tightness detection in this step avoids the unqualified products to flow into the subsequent process, improves the processing efficiency, and reduces the cost.

[0072] In some embodiments, before the heat exchange tube 1 and the fin are assembled, an aluminum material or a nickel material is plated on at least a part of the surface of the heat exchange tube 1 to form a coating.

[0073] Wherein, in the embodiments of the present disclosure, after the step S21 is completed, the heat exchange tube 1 with the first tube 2 after welding is completed, and the aluminum material or the nickel material is arranged on at least a part of the surface of the heat exchange tube 1 to form a coating.

[0074] Wherein, the aluminum material or the nickel material is arranged on the outer surface of the heat exchange tube 1 at least in the region of the heat exchange tube 1 connected with the fin, so that the heat exchange tube 1 can be better welded with the fin 4, and the welding reliability is improved. Wherein, the aluminum material or the nickel material can also form a coating on the outer surface of the heat exchange tube 1.

[0075] In the step of arranging the aluminum material on the surface of the heat exchange tube, the coating is formed by hot dipping or arc spraying. Wherein, the aluminum material can be aluminum or aluminum alloy. By arranging the aluminum coating on the surface of the heat exchange tube, the stainless steel heat exchange tube 1 and the aluminum fin 4 are welded to become aluminum and aluminum welding, a good joint is formed at the connection of the heat exchange tube 1 and the fin 4, the continuous brittle intermetallic compound in the weld seam on the side of the heat exchange tube 1 is reduced, the welding reliability of the heat exchange tube 1 and the fin is improved, the risk of leakage is reduced, and the reliability of the heat exchanger 10 is improved.

[0076] In the step of arranging the nickel material on the surface of the heat exchange tube, the coating is formed by chemical plating or electroplating; and / or, after the chemical plating or electroplating of the nickel material, a heat treatment of 400°C for 1 hour in a vacuum furnace or a gas protection furnace is carried out. Wherein, the nickel material can be nickel-phosphorus alloy. By arranging the nickel coating on the surface of the heat exchange tube, a good joint is formed when the heat exchange tube 1 and the fin 4 are welded, the continuous brittle intermetallic compound in the weld seam on the side of the heat exchange tube 1 is reduced, the welding reliability of the heat exchange tube 1 and the fin is improved, the risk of leakage is reduced, and the reliability of the heat exchanger 10 is improved.

[0077] In some embodiments, the aluminum material or the nickel material can be arranged on at least a part of the outer surface of the heat exchange tube 1 to form a coating after the heat exchange tube 1 is connected with the first tube in step S11; wherein the coating is formed by plating or coating the aluminum material or the nickel material, and the melting point of the coating is high, and does not affect the wetting and gap filling of the nickel-based filler metal when the heat exchange tube 1 and the first tube are welded.

[0078] In some embodiments, the thickness of the coating formed on the surface of the heat exchange tube in the step of arranging the nickel material on at least a part of the surface of the heat exchange tube is 5-20 μm. The thickness of the nickel coating formed on the surface of the heat exchange tube is 5-20 μm, because the reaction speed of nickel is slow. When the thickness of the nickel coating is less than 5 μm, the thickness of the coating is insufficient to react with stainless steel to form a good joint, which affects the welding reliability. When the thickness of the nickel coating is greater than 20 μm, the thickness of the reaction layer formed is thick, and the processing cost is increased.

[0079] In some embodiments, the thickness of the coating formed on the surface of the heat exchange tube in the step of arranging the aluminum material on at least a part of the surface of the heat exchange tube is 30-150 μm. When the thickness of the aluminum coating is less than 30 μm, the thickness of the coating is insufficient to react to form a good joint, which affects the welding reliability. When the thickness of the aluminum coating is greater than 150 μm, the thickness of the reaction layer formed is thick, and the processing cost is increased.

[0080] In some embodiments, the thickness of the coating formed on the surface of the heat exchange tube in the step of arranging the aluminum material on at least a part of the surface of the heat exchange tube is 30-150 μm. When the thickness of the aluminum coating is less than 30 μm, the thickness of the coating is insufficient to react to form a good joint, which affects the welding reliability. When the thickness of the aluminum coating is greater than 150 μm, the thickness of the reaction layer formed is thick, and the processing cost is increased.

[0081] In some embodiments, the thickness of the coating formed on the surface of the heat exchange tube in the step of arranging the aluminum material on at least a part of the surface of the heat exchange tube is 30-150 μm. When the thickness of the aluminum coating is less than 30 μm, the thickness of the coating is insufficient to react to form a good joint, which affects the welding reliability. When the thickness of the aluminum coating is greater than 150 μm, the thickness of the reaction layer formed is thick, and the processing cost is increased.

[0082] The electroless nickel plating includes pre-treatment, nickel plating and post-treatment. The pre-treatment mainly includes oil removal, rust removal, water washing and the like. The nickel plating process is performed by immersing the whole stainless steel frame formed by the welded heat exchange tube 1 and the first tube in a plating bath containing a bath solution, mainly including nickel salt such as nickel sulfate, reducing agent such as hypophosphite (electroless nickel-phosphorus), sodium borohydride (electroless nickel-boron), and additives such as complexing agent, stabilizer, accelerator, buffer and the like. In the process, the nickel material forms a nickel layer and an iron-nickel compound layer on the surface of the stainless steel, and the nickel layer is located on the outside. The post-treatment process includes passivation, dehydrogenation and heat treatment, and the post-treatment is not a necessary process, which can be adjusted according to the processing process. The heat treatment in the post-treatment process can change the structure and performance of the coating, such as improving the hardness and changing the corrosion resistance. For example, the workpiece after electroless nickel-phosphorus plating is subjected to heat treatment at 400°C for 1 hour in a vacuum furnace or a gas protection furnace, so that the amorphous plating layer is basically completely crystallized, and the hardness of the coating is also greatly improved.

[0083] It should be noted that, in order to realize the welding of the heat exchange tube 1 and the fin 4, the coating on the surface of the heat exchange tube 1 in the embodiment of the present disclosure can meet the requirements of welding as long as the coating is in good condition. For example, the thickness of the nickel coating ranges from 5μm to 20μm.

[0084] In some embodiments, the nickel coating on the surface of the heat exchange tube can also be formed by electroplating. After forming the nickel coating on the surface of the stainless steel, heat treatment at 400°C for 1 hour in a vacuum furnace or a gas protection furnace can be performed to improve the hardness of the nickel coating, thereby further improving the reliability of the welded part.

[0085] In some embodiments, the coating is formed by plating aluminum material on at least a part of the surface of the heat exchange tube 1 to realize reliable welding of the heat exchange tube 1 and the fin 4. The aluminum material is plated on at least a part of the outer surface of the heat exchange tube 1. When the stainless steel heat exchange tube 1 and the aluminum fin are welded, the welding becomes aluminum and aluminum material, which reduces the brittle intermetallic compound formed on the surface of the material when different materials are welded, improves the welding strength, and improves the welding reliability of the heat exchange tube 1 and the fin 4.

[0086] The hot-dip aluminum plating of the stainless steel structure can include pre-treatment, preheating, hot-dip plating and post-plating treatment. The pre-treatment mainly includes oil removal (such as alkali washing), water washing, rust removal (such as pickling), water washing, flux treatment (such as fluoride, chloride and other fluxes, which have the functions of preventing oxidation and assisting plating), and drying. The preheating temperature ranges from 300 to 500°C. The preheating process removes the crystallization water remaining in the flux and reduces the temperature fluctuation of the hot-dip plating bath.

[0087] In the hot-dip plating process of the overall stainless steel frame, the plating solution is pure aluminum, aluminum-silicon alloy, etc. Silicon can reduce the interfacial reaction speed of steel and aluminum, so that the reaction layer thickness of steel and aluminum-silicon alloy plating solution under the same parameters is lower than that of steel and aluminum plating solution. In order to reduce the oxidation of the plating solution, the plating solution can be protected by inert gas (such as argon) or reducing gas (such as nitrogen + 5% hydrogen, etc.). For example, when the plating solution is pure aluminum, the process parameters for hot-dip aluminum plating are 680-800°C, and the immersion plating time is from several seconds to several minutes. When the plating solution is aluminum-silicon alloy, for example, aluminum-silicon alloy Al-10wt.%Si, the process parameters for hot-dip aluminum plating are 600-750°C, and the immersion plating time is from several seconds to several minutes. The higher the process parameter temperature and the longer the time in the hot-dip plating process, the thicker the compound layer, and the higher the resistance to high-temperature oxidation, but the brittleness increases, which is not conducive to subsequent deformation processing. Post-plating treatment is mainly to perform size consistency treatment to improve the uniformity of the coating, thereby further improving the welding reliability of the heat exchange tube 1 and the first tube 2.

[0088] In some embodiments, in the case of hot-dip plating with pure aluminum, for example, using standard aluminum ingots with a purity of 99.7%, the immersion plating parameters are 700-750°C, wherein the aluminum material forms an iron-aluminum compound layer and an aluminum layer on the surface of the stainless steel, and the aluminum layer is located on the outside. The aluminum layer on the outside can greatly improve the welding strength when welded with aluminum fins. Subsequently, the fins can be fitted and installed, and the assembly of the heat exchanger 10 is completed. When welding the composite fins, a fluorine aluminates soldering agent with a concentration of 3-5% is sprayed, and the maximum welding temperature of the NB continuous aluminum soldering furnace (NB furnace) can be set to 600-615°C, and the time above 585°C can be controlled to 0.5-10 min.

[0089] In some embodiments, in the case of hot-dip plating with aluminum-silicon alloy, for example, Al-10%Si, etc. can be used, and the immersion plating parameters can be selected as 600°C, and the immersion plating time is controlled to be 15s or less. The aluminum material forms an iron-aluminum-silicon compound layer and an aluminum layer on the surface of the stainless steel tube, and the aluminum coating is located on the outside. The aluminum layer on the outside can greatly improve the welding strength when welded with aluminum fins. Subsequently, the fins can be fitted and installed, and the assembly of the heat exchanger 10 is completed. When welding the fins, a fluorine aluminates soldering agent with a concentration of 3-5% can be sprayed, and the maximum welding temperature of the NB furnace can be set to 605°C, and the time above 585°C can be controlled to 0.5-10 min, etc.

[0090] Further, after the overall stainless steel frame is hot-dip plated with aluminum, it needs to be welded with fins. In order to avoid the iron-aluminum and iron-aluminum-silicon compound layers on the stainless steel side interface being too thick during the two heat processes, which can increase the brittleness of the joint and even cause cracking, a high-temperature short-time process is used during the overall hot-dip plating of the stainless steel, for example, the high-temperature residence time is controlled to be 10s or less, which can further reduce the cracking of the welding joint and improve the welding reliability.

[0091] In some embodiments, the aluminum material can also be coated on the surface of the heat exchange tube by arc spraying to form an aluminum coating. The aluminum material is coated on the surface of the heat exchange tube to improve the corrosion resistance of the heat exchange tube 1 and the welding performance of the heat exchange tube 1 and the fin 4. The aluminum coating formed by arc spraying can be locally sprayed with aluminum, and the process is simple and the flow is short.

[0092] In step S31, the fin can be a flat fin, a windowed fin, a corrugated fin, etc., and the material is aluminum or aluminum alloy, so as to reduce the adverse effect of the thermal resistance of the stainless steel heat exchange tube on the heat exchange capacity of the heat exchanger 10 and enhance the heat exchange capacity. In the case where the fin 4 is made of aluminum alloy, the thermal conductivity and cost performance are better than when it is made of aluminum.

[0093] In the embodiments of the present disclosure, at least part of the fin 4 is installed between adjacent heat exchange tubes 1 to complete the assembly of the fin and the heat exchange tube. As shown in FIGS. 1-2, a plurality of fins 4 are respectively arranged between adjacent heat exchange tubes 1 to complete the assembly of the fin and the heat exchange tube. As shown in FIG. 3, the heat exchange tube 1 passes through the through slot of the fin 4, that is, the heat exchange tube 1 is inserted from the through slot of the fin 4, and the end portions of different heat exchange tubes 1 are communicated through the bent first pipe 2. As shown in FIGS. 4 and 5, the heat exchange tube 1 passes through the through slot of the fin 4, and the heat exchange tube 1 is inserted from the through slot of the fin 4. As shown in FIG. 6, the heat exchange tube 1 passes through the through hole of the fin 4, and the heat exchange tube 1 is inserted from the through hole of the fin 4. The end portions of a plurality of heat exchange tubes 1 are inserted into the first pipe 2, and the end portions of the heat exchange tubes 1 are communicated through the first pipe 2.

[0094] In some embodiments, when the fin contains at least 2.0% silicon, flux is used for brazing in gas protection, or when the fin contains less than 2.0% silicon, aluminum-silicon-based filler metal is used with flux for brazing in gas protection.

[0095] In other words, the fin 4 is generally divided into single-layer fins and composite fins, that is, the fin 4 can be a single-layer fin or a composite fin, and the fin material of the composite fin includes at least two layers of material. When the single-layer fin contains at least 2.0% silicon, flux is used for brazing in gas protection, and when the single-layer fin contains less than 2.0% silicon, aluminum-silicon-based filler metal is used with flux for brazing in gas protection. The composite layer of the composite fin contains 6%-12% silicon, which is directly brazed with other components in gas protection using flux.

[0096] In the case of the single-layer fin 4 containing 2.0%-3.0% silicon, the fin can be directly welded to the heat exchange tube 1 as the composite fin. In addition, in the case of the single-layer fin containing 2.0%-3.0% silicon, the fin and the heat exchange tube 1 are in contact with the liquid filler metal of the stainless steel heat exchange tube 1 at the welding position, thereby reducing the thickness of the reaction layer during welding of the fin 4 and the heat exchange tube 1, i.e., reducing the thickness of the brittle intermetallic compound, reducing the risk of thermal stress and cracking, and improving the welding reliability. In some embodiments, the main material composition of the fin can include Si: 2.0%-3.0%, Fe≤0.70%, Mn: 0.4%-1.8%, Zn≤2.0%, and the balance of Al and unavoidable impurities.

[0097] In the case of the fin 4 being a composite fin, the composite fin includes a composite layer containing 6%-12% silicon, and the welding to the heat exchange tube 1 is achieved through the composite layer.

[0098] In the case of the fin 4 being a single-layer fin with a silicon content less than 2%, the low-silicon-content fin is not sufficient for direct welding to the heat exchange tube 1. In the process of assembling the fin 4 and the heat exchange tube 1, a brazing material such as an aluminum-silicon-based filler metal brazing foil is placed at the connection between the heat exchange tube 1 and the fin 4 to achieve the welding of the fin 4 to the heat exchange tube 1. The composite fin and the single-layer fin containing 2.0%-3.0% silicon described above do not require additional placement of brazing material during assembly with the heat exchange tube 1.

[0099] In step S41, the heat exchange tube 1 and the fin 4 are welded together. The welding method between the fin 4 and the heat exchange tube 1 can be brazing, i.e., the components are welded together by brazing, which reduces the contact thermal resistance and improves the heat exchange capacity of the stainless steel heat exchange tube and the aluminum fin to form the heat exchanger 10, thereby reducing the adverse effects of the stainless steel thermal resistance on the heat exchange capacity of the heat exchanger 10. For example, the assembled fin and heat exchange tube 1 of step S31 are placed on a heat-resistant tooling with fixing and supporting functions, the assembled structure is placed in a heating furnace together with the heat-resistant tooling, and the structure is heated, held, and cooled according to a set program to complete the welding of the heat exchange tube 1 and the fin 4.

[0100] In some embodiments, in the step of welding the heat exchange tube 1 and the fins, the soldering process can use a flux in gas protection brazing, and the flux can include a fluoroaluminate type flux. The fluoroaluminate type flux can be a potassium fluoroaluminate flux to which cesium fluoroaluminate is added. The addition of cesium fluoroaluminate to the potassium fluoroaluminate flux can improve the welding quality of the potassium fluoroaluminate flux in welding the stainless steel heat exchange tube and the aluminum fins. The melting temperature of the potassium fluoroaluminate flux is about 565°C, and the melting temperature of the cesium fluoroaluminate is lower than that of the potassium fluoroaluminate. During the brazing temperature rising process, the oxide film on the stainless steel structure can be better removed, so that the welding stability of the fins and the heat exchange tube 1 is better, and the welding reliability is improved.

[0101] In specific embodiments, the flux can be exemplified by a mixture of potassium fluoroaluminate and cesium fluoroaluminate fluxes with a concentration of 5-20% and a mass ratio of 1-5:1. The concentration of the potassium fluoroaluminate flux can also be adaptively adjusted, such as a potassium fluoroaluminate flux with a concentration of 3-20%.

[0102] In the embodiments of the present disclosure, when the heat exchange tube 1 and the fins 4 are welded, the welding temperature and the activity temperature of the solder are both near 600°C. In the case of spraying the flux on the heat exchange tube 1 and the fin structure, the oxide film at this position can be removed or partially removed at the welding temperature of 600°C. However, the protective oxide film on the stainless steel structure at this position can still be formed again after welding. Therefore, when the heat exchange tube 1 and the first tube 2 are welded first, and then the heat exchange tube 1 and the fins 4 are welded, the welding stability of the heat exchange tube 1 and the first tube 2 will not be affected. In addition, in some schemes, the first tube area can also be shielded in the case of spraying the flux on the heat exchange tube 1 and the fin structure.

[0103] In some embodiments, after the heat exchange tube 1 and the first tube 2 are welded, the heat exchange tube 1 and the fins 4 are welded. This processing method first welds the stainless steel heat exchange tube and the stainless steel first tube, and then welds the stainless steel heat exchange tube and the aluminum fins. By welding the first tube 2 and the heat exchange tube 1 and the heat exchange tube 1 and the fins 4 respectively, the joints of the heat exchanger with different materials at the connection between the first tube 2 and the heat exchange tube 1 and at the connection between the heat exchange tube 1 and the fins 4 are all welded well, the welding reliability is improved, and the risk of leakage of the heat exchanger is reduced.

[0104] In this embodiment, the melting temperature of the solder for welding the heat exchange tube 1 and the first tube 2 is T1, and the melting temperature of the solder for welding the heat exchange tube 1 and the fins 4 is T2, T1-T2>100°C.

[0105] In the processing method of welding the heat exchange tube 1 and the first tube 2 first and then welding the heat exchange tube 1 and the fin 4, the melting temperature of the welding material in the welding of the heat exchange tube 1 and the first tube 2 in step S21 is T1, the melting temperature of the welding material in the welding in step S41 is T2, and T1-T2>100℃; in other words, when the stainless steel heat exchange tube 1 and the stainless steel first tube 2 are welded, the melting temperature of the welding material is higher than the melting temperature of the welding material when the stainless steel heat exchange tube 1 and the aluminum fin 4 are welded by more than 100℃, so as to ensure that, in the processing method of welding the heat exchange tube 1 and the first tube 2 first and then welding the heat exchange tube 1 and the fin 4, the welding of the heat exchange tube 1 and the fin in step S41 does not affect the welding stability of the heat exchange tube 1 and the first tube 2, and the welding reliability of the heat exchanger 10 is improved.

[0106] In some embodiments, in the welding step of the heat exchange tube 1 and the fin 4, the time when the welding temperature is greater than 585℃ is controlled to be 0.5-10min.

[0107] In some embodiments, the residence time at high temperature, especially the time when the welding material is in liquid state, is reduced, which reduces the thickness of the reaction layer and reduces the risk of thermal stress and cracking in the welding joint of the heat exchange tube 1 and the fin. In other words, in the brazing processing of the heat exchange tube 1 and the fin, the time when the welding temperature is greater than 585℃ is controlled to be no more than 10min, for example, it can be 585℃, 590℃, 595℃, 600℃, etc., which reduces the residence time at high temperature, reduces the thickness of the reaction layer, reduces the risk of thermal stress and cracking at the welding joint, and further improves the reliability of the welding joint.

[0108] In some embodiments, the heat exchange tube 1 and the fin 4 can be welded first, and then the heat exchange tube 1 and the first tube 2 can be welded. Laser welding can be used to weld the heat exchange tube 1 and the first tube; or arc welding can be used to weld the heat exchange tube 1 and the first tube; or silver brazing material or nickel-based brazing material or manganese-based brazing material can be used for induction brazing; or silver brazing material can be used for flame brazing.

[0109] Embodiments of the present disclosure provide a method of welding a stainless steel heat exchange tube 1 and a fin 4 first and then locally welding a heat exchange tube 1 and a first tube 2, which realizes that the joints of the heat exchanger with different materials at the connection between the heat exchange tube 1 and the fin 4 and at the connection between the first tube 2 and the heat exchange tube 1 are all welded well, improves the welding reliability, reduces the risk of leakage of the heat exchanger, and improves the reliability of the heat exchange tube.

[0110] The aluminum material or the nickel material can be coated on at least part of the surface of the heat exchange tube 1 to form a coating before the heat exchange tube 1 and the fin 4 are assembled. The aluminum material or the nickel material is coated on at least part of the outer surface of the heat exchange tube 1, at least in the region where the heat exchange tube 1 is connected to the fin 4, so that the heat exchange tube 1 can be better welded to the fin 4. The aluminum material or the nickel material can also be coated on the entire outer surface of the heat exchange tube 1. The aluminum material is pure aluminum or an aluminum alloy, and the nickel material is pure nickel or a nickel alloy, which can be a nickel-phosphorus alloy.

[0111] In the step of coating the aluminum material on the outer surface of the heat exchange tube 1, the coating can be formed by hot dipping or arc spraying. When the aluminum material is coated on at least part of the surface of the heat exchange tube 1 by arc spraying, the aluminum can be sprayed locally, and the surface of the heat exchange tube 1 in the region where the heat exchange tube 1 is connected to the fin 4 can be sprayed. The process is simple, the flow is short, and the operation is more convenient. When the aluminum material is plated on the surface of the heat exchange tube 1 by hot dipping, the specific steps are not repeated here. However, when the heat exchange tube 1 is dipped, the ends of the heat exchange tube 1 are sealed to prevent the channels at the ends of the heat exchange tube 1 from being blocked when the aluminum material is dipped onto the surface of the heat exchange tube 1, affecting the reliability of the heat exchanger.

[0112] In the step of coating the nickel material on the outer surface of the heat exchange tube, the coating can be formed by chemical plating or electroplating. The specific steps are not repeated here. However, when the heat exchange tube 1 is dipped, the ends of the heat exchange tube 1 are sealed to prevent the channels at the ends of the heat exchange tube 1 from being blocked when the nickel material is dipped onto the outer surface of the heat exchange tube 1, affecting the reliability of the heat exchanger.

[0113] In assembling the fin 4 and the heat exchange tube 1, the fin 4 can be mounted between adjacent heat exchange tubes 1 as shown in Figs. 1-2, or the heat exchange tube 1 can pass through the through slot of the fin 4 as shown in Figs. 3-5, or the heat exchange tube 1 can pass through the through hole of the fin 4 as shown in Fig. 6, and the heat exchange tube 1 and the fin 4 are welded, and then the heat exchange tube 1 and the first tube 2 are partially welded. The heat exchange tube 1 and the fin 4 are welded by brazing, which improves the heat exchange capacity of the heat exchanger 10 composed of the stainless steel heat exchange tube and the aluminum fin by reducing the contact thermal resistance.

[0114] In some embodiments, when welding the heat exchange tube 1 and the fin 4, a flux is used for brazing in a gas protection, the flux includes fluoroaluminate type flux; when the fin contains at least 2.0% of silicon, the flux is used for brazing in a gas protection; or when the fin contains less than 2.0% of silicon, an aluminum-silicon based filler metal is used for brazing in a gas protection with a flux; in the step of welding the heat exchange tube 1 and the fin 4, the temperature is controlled to be greater than 585°C for 0.5-10 minutes, and the specific steps are not described again in the above content.

[0115] After the heat exchange tube 1 and the fin 4 are welded, step S11 of assembling the heat exchange tube 1 and the first tube 2 is performed. The assembly of the heat exchange tube 1 and the first tube 2 is mainly to complete the connection of the heat exchange tube 1 and the first tube 2 and other pipe assembly parts, which is achieved by assembling the heat exchange tube 1 and the first tube 2 in the heat exchanger 10 shown in FIGS. 1-4 according to requirements. The assembly can also include other pipe assemblies connected to the first tube 2, such as end covers, inlet and outlet tubes, partitions, mounting brackets, etc. The pipe assemblies can also be made of stainless steel.

[0116] After the heat exchange tube 1 and the first tube 2 are assembled, step S21 of welding the heat exchange tube 1 and the first tube 2 is performed. In the welding of the heat exchange tube 1 and the first tube 2, local welding can be used, and the welding can include laser welding, arc welding, induction brazing with silver filler metal or nickel-based filler metal or manganese-based filler metal, or flame brazing with silver filler metal. When welding, the connection between the heat exchange tube 1 and the first tube 2 is locally welded, which does not affect the welding of the heat exchange tube 1 and the fin 4 that has been completed. This method is more efficient and has strong applicability. The above-mentioned methods can refer to related technologies and will not be described again.

[0117] When the heat exchange tube 1 and the first tube 2 are locally welded using filler metal, the gap between the heat exchange tube 1 and the first tube 2 can also be controlled to be within the range of 0.03-0.25 mm to reduce the possibility that a small or large gap at the connection may cause the filler metal to be unable to fill the weld and leak, or the weld to be too brittle and the connection joint strength to be low. The volume of the filler metal in the gap is controlled to be 2-5 times the volume of the gap, i.e., the volume of the filler metal in the gap is 2-5 times the theoretical volume of the weld. The melted filler metal can fully fill the gap between the heat exchange tube 1 and the first tube 2, improving the reliability of the welding.

[0118] In order to further understand the present application, the scheme of the present application will be further described in conjunction with the embodiments. Those skilled in the art will understand that only some examples are described in the present application, and any other suitable specific examples are within the scope of the present application.

[0119] Embodiment 1

[0120] Based on the foregoing description, a heat exchanger as shown in Figure 1 or Figure 2 is made. The stainless steel parts use OCr18Ni9 stainless steel material, and the stainless steel parts of the heat exchanger are assembled according to requirements, that is, the heat exchange pipe 1 and the first pipe 2 are assembled first, and other pipe assemblies can also be assembled. The parts are spot-welded by TIG self-melting, and BNi82CrSiB welding paste is applied near the welding position. The stainless steel welding gap is controlled to be 0.05mm, and the welding paste of each welding is controlled to be 2 times the volume of the solder in the welding paste. The assembled stainless steel part of the heat exchanger is placed on a 0Cr18Ni9 tool, and they are put into a vacuum brazing furnace for welding. The vacuum degree of the furnace body is better than 10 -2 Pa, the heating rate is 20℃ / min, the brazing temperature is set to 1050℃, and the holding time at the brazing temperature is 15min. After furnace cooling, the furnace temperature is 200℃, and the welding of the stainless steel part of the heat exchanger is completed.

[0121] After the first brazing of the stainless steel part, the 4343 / 3003 / 4343 composite fin after forming is assembled between the stainless steel heat exchange pipes, and after assembly, the fin is fixed by 0Cr18Ni9 stainless steel wire. The bundled heat exchanger is placed on a stainless steel bracket and placed in a nitrogen-protected continuous brazing furnace for brazing. Between the heat exchanger entering the brazing heating zone, a 20% concentration of equal mass ratio of potassium fluoroaluminate and cesium fluoroaluminate flux is used for spraying treatment of the core, and the flux is applied. After drying at a set temperature of 200℃, it enters the brazing section of the furnace body, and the maximum temperature of the brazing section is set to 605℃, and the time above 590℃ is 3 minutes. After cooling and leaving the furnace, the heat exchanger product is obtained.

[0122] Example 2

[0123] Based on the foregoing description, a heat exchanger as shown in Figure 1 or Figure 2 is made. The stainless steel parts use OCr18Ni9 stainless steel material, and the stainless steel parts of the heat exchanger are assembled according to requirements, that is, the heat exchange pipe 1 and the first pipe 2 are assembled first, and other pipe assemblies can also be assembled. The parts are spot-welded by TIG self-melting, and BNi82CrSiB welding paste is applied near the welding position. The stainless steel welding gap is controlled to be 0.05mm, and the welding paste of each welding is controlled to be 2 times the volume of the solder in the welding paste. The assembled stainless steel part of the heat exchanger is placed on a 0Cr18Ni9 tool, and they are put into a vacuum brazing furnace for welding. The vacuum degree of the furnace body is better than 10 -2 Pa, the heating rate is 20℃ / min, the brazing temperature is set to 1050℃, and the holding time at the brazing temperature is 15min. After furnace cooling, the furnace temperature is 200℃, and the welding of the stainless steel part of the heat exchanger is completed.

[0124] After the stainless steel part after the first brazing is qualified by helium detection, the formed 3003+2.4%Si single-layer fin is assembled between the stainless steel heat exchange pipes, and after the assembly is completed, the fins are fixed by overall binding with 0Cr18Ni9 stainless steel wire. The bundled heat exchanger is placed on the stainless steel bracket and placed in the nitrogen protection continuous brazing furnace for brazing. Between the heat exchanger entering the brazing heating area, the core is sprayed with a mixed flux of potassium fluoroaluminate and cesium fluoroaluminate with a concentration of 5% and an equal mass ratio. Apply the flux, then pass through the drying zone set at 200°C, and then enter the brazing section of the furnace body. The highest temperature of the brazing section is set to 610°C, and the time above 590°C is 2 minutes. After cooling out of the furnace, the heat exchanger product is obtained.

[0125] Example 3

[0126] Based on the foregoing description, a heat exchanger as shown in FIG. 1 or 2 is made. The stainless steel parts are made of O0Cr19Ni10 stainless steel material, and the assembled heat exchange pipes 1 and first pipes 2 and other stainless steel parts are spot-welded by TIG self-melting. The welding paste of BNi71CrSi is applied near the welding seam position that needs to be welded. The gap of the stainless steel welding seam is controlled to be 0.05mm, and the amount of welding paste applied to each welding seam is controlled to be 4 times the volume of the solder in the welding paste. The volume of the welding seam is the theoretical volume. The assembled stainless steel part of the heat exchanger is placed on the tooling of 0Cr18Ni9 material and placed in a vacuum brazing furnace for welding. The vacuum degree of the furnace body is better than 10 -2 Pa, the heating rate is 15°C / min, the brazing temperature is set to 1170°C, the holding time at the brazing temperature is 10 min, and the brazing temperature is cooled to 1000°C for 1 h of post-brazing diffusion treatment. The furnace cooling temperature is 200°C, and the stainless steel part of the heat exchanger is obtained.

[0127] After the stainless steel part after the first brazing is qualified by helium detection, the formed 3003+2.4%Si single-layer fin is assembled between the stainless steel heat exchange pipes, and after the assembly is completed, the fins are fixed by overall binding with 0Cr18Ni9 stainless steel wire. The bundled heat exchanger is placed on the stainless steel bracket and placed in the nitrogen protection continuous brazing furnace for brazing. Between the heat exchanger entering the brazing heating area, the core is sprayed with a mixed flux of potassium fluoroaluminate and cesium fluoroaluminate with a concentration of 5% and an equal mass ratio. Apply the flux, then pass through the drying zone set at 200°C, and then enter the brazing section of the furnace body. The highest temperature of the brazing section is set to 610°C, and the time above 590°C is 2 minutes. After cooling out of the furnace, the heat exchanger product is obtained.

[0128] Example 4

[0129] Based on the foregoing description, the heat exchanger as shown in Figure 2 is made. The stainless steel parts are made of stainless steel material of O0Cr19Ni10, the heat exchange tube 1 and the first tube 2 and other stainless steel parts are assembled first, the parts are spot-welded by TIG self-melting, and the welding paste of BNi71CrSi is applied near the welding position. The gap of the stainless steel weld is controlled to be 0.05mm, and the amount of welding paste applied to each weld is controlled to be 3 times the volume of solder in the welding paste. The assembled stainless steel parts of the heat exchanger are placed on a tooling of 0Cr18Ni9 material, and are placed in a vacuum brazing furnace together for welding. The vacuum degree of the furnace body is better than 10 -2 Pa, the heating rate is 20℃ / min, the brazing temperature is set to 1170℃, and the holding time at the brazing temperature is 10min. After holding at the brazing temperature, the temperature is lowered to 1000℃ for 1h of post-brazing diffusion treatment. After cooling in the furnace, the furnace temperature is 200℃, and the welding of the stainless steel part of the heat exchanger is completed.

[0130] After the first brazing of the stainless steel part, the part is subjected to nickel plating treatment, and the thickness of the nickel plating layer is between 5μm. The formed 3003 fins are assembled between the nickel-plated heat exchange tubes, and the 4047 brazing foil is placed between the fins 4 and the stainless steel heat exchange tube 1. The thickness of the 4047 brazing foil is 0.01mm, the width is the same as the width of the stainless steel heat exchange tube 1, and the length is the same as the length of the formed fins. After assembly, the heat exchange tube 1 and the fin 4 are fixed by 0Cr18Ni9 stainless steel wire. The bundled heat exchanger is placed on a stainless steel bracket and placed in a nitrogen-protected continuous brazing furnace for brazing. Between the heat exchanger entering the brazing heating zone, the mixed flux of 10% fluorine aluminic acid potassium and fluorine aluminic acid cesium (mass ratio of fluorine aluminic acid potassium to fluorine aluminic acid cesium is 2:1) is used for spraying treatment on the core of the heat exchanger, and then it passes through the drying zone with a set temperature of 200℃ and enters the brazing section of the furnace body. The highest temperature of the brazing section is set to 605℃, and the time above 585℃ is 2 minutes. After cooling and leaving the furnace, the heat exchanger product is obtained.

[0131] Example 5

[0132] Based on the foregoing description, a heat exchanger as shown in FIG. 3 is made. The stainless steel parts are made of 0Cr17Ni12Mo2 stainless steel material, that is, the stainless steel parts such as the heat exchange pipe 1 and the first pipe 2 are assembled first, including connecting the end of the heat exchange pipe 1 with the first pipe 2, the parts are spot-welded by TIG self-melting, and the welding paste of BNi82CrSiB is applied near the welding position. The stainless steel welding gap is controlled to be 0.06 mm, and the welding paste of each welding is controlled to be 5 times the volume of the solder in the welding paste to the theoretical volume of the welding. The assembled stainless steel parts of the heat exchanger are placed on the tooling of 0Cr18Ni9 material, and are put into the vacuum brazing furnace together for welding. The vacuum degree of the furnace body is better than 10 -2 Pa, the heating rate is 15℃ / min, the brazing temperature is set to 1050℃, and the holding time at the brazing temperature is 15 min. After cooling in the furnace, the out-of-furnace temperature is 200℃ to obtain the stainless steel part of the heat exchanger.

[0133] After the stainless steel part after the first brazing passes the helium test, the formed 4045 / 3003 / 4045 composite fin is assembled with the heat exchange pipe, the heat exchange pipe passes through the through slot on the fin to be fixed, and after the assembly is completed, the heat exchanger is held by the 0Cr18Ni9 stainless steel tray. The heat exchanger is placed in the nitrogen-protected continuous brazing furnace together with the tray for brazing. Between the heat exchanger entering the brazing heating zone, the mixed flux of potassium fluoroaluminate and cesium fluoroaluminate with a concentration of 5-20% (the mass ratio of potassium fluoroaluminate to cesium fluoroaluminate is 3:1) is used for spraying treatment of the heat exchanger, and the flux is applied. The tray is pre-punched to discharge excess flux, and then passes through the drying zone with a set temperature of 200℃ to enter the brazing section of the furnace body, and the highest temperature of the brazing section is set to 605℃, and the holding time above 585℃ is 3 minutes. After cooling and leaving the furnace, the heat exchanger product is obtained.

[0134] Example 6

[0135] Based on the foregoing description, a heat exchanger as shown in FIG. 4 is made. The stainless steel parts are made of 00Cr17Ni14Mo2 stainless steel material, that is, the stainless steel parts such as the heat exchange pipe 1 and the first pipe 2 are assembled first, the parts are spot-welded by TIG self-melting, and the welding paste of BNi82CrSiB is applied near the welding position. The stainless steel welding gap is controlled to be 0.08 mm, and the welding paste of each welding is controlled to be 2 times the volume of the solder in the welding paste to the theoretical volume of the welding. The assembled stainless steel parts of the heat exchanger are placed on the tooling of 0Cr18Ni9 material, and are put into the vacuum brazing furnace together for welding. The vacuum degree of the furnace body is better than 10 -2Pa, the heating rate is 20℃ / min, the brazing temperature is set to 1050℃, the holding time at the brazing temperature is 15min, and the brazing temperature is cooled to 1000℃ for 1h post-brazing diffusion treatment. After furnace cooling, the out-of-furnace temperature is 200℃, and the welding of the stainless steel part of the heat exchanger is completed.

[0136] After the first brazing of the stainless steel part passes the helium detection, the formed 4045 / 3003 / 4045 composite fin is assembled with the heat exchange tube, the heat exchange tube passes through the through slot on the fin, and after assembly, the heat exchanger is held by a 0Cr18Ni9 stainless steel tray. The heat exchanger is placed in a nitrogen-protected continuous brazing furnace for brazing. When the heat exchanger enters the brazing heating zone, a mixture of potassium fluoroaluminate and cesium fluoroaluminate with a concentration of 5-20% is used for spraying treatment of the heat exchanger, wherein the mass ratio of potassium fluoroaluminate to cesium fluoroaluminate is 3:1, the flux is applied, the tray is pre-punched to discharge excess flux, and then passes through the drying zone with a set temperature of 200℃ and enters the brazing section of the furnace body, the highest temperature of the brazing section is set to 605℃, and the time above 585℃ is 1min. After cooling and leaving the furnace, the heat exchanger product is obtained.

[0137] Example 7

[0138] The difference from Example 2 is that in step S21, when the heat exchange tube 1 is welded with the first tube 2, BMn70NiCr is used as the solder, the stainless steel weld gap is controlled to be 0.25mm, the welding process parameters are 1150-1180℃, the holding time is 10min, and the brazing is carried out under argon protection, and the out-of-furnace temperature is not more than 200℃. In this embodiment, the corrosion resistance of the first tube 2 is not as good as that of Example 2, and when a high-temperature copper solder containing higher Mn is used to replace BMn70NiCr as the solder in the embodiments of the present disclosure, the corrosion resistance of the stainless steel first tube is also not as good as that of Example 2. In the corrosion resistance test, generally, the SWAAT standard of ASTM G85 is used, and when the box temperature is 49℃, the inlet and outlet tubes are protected by electrician's tape during the test, and whether the heat exchanger sample leaks within a certain time is tested, and the time when the leakage occurs can also be tested. According to the test time and leakage time, the longer the time without leakage, the stronger the corrosion resistance.

[0139] Example 8

[0140] The difference from Example 2 is that in step S21, when the heat exchange tube 1 is welded with the first tube 2, silver self-brazing solder is used as the solder, the stainless steel weld gap is controlled to be 0.2mm, the welding process parameters are 600-900℃, the holding time is 10min, and the brazing is carried out under argon protection. In this embodiment, the corrosion resistance of the stainless steel joint is not as good as that of Example 2, and the first tube needs to be cleaned after welding.

[0141] Example 9

[0142] The difference between this example and Example 3 is that in step S21, when the heat exchange tube 1 is welded with the first tube 2, silver solder is used as the solder to cooperate with borate fluoride flux to perform induction brazing or flame brazing. In this example, the borate fluoride flux remaining after welding needs to be cleaned, and the oxidation film of the stainless steel structure is thickened, which increases the difficulty of subsequent welding of the heat exchange tube and the fins, causing the welding to be faulty.

[0143] Example 10

[0144] The difference between this example and Example 4 is that after the first brazing of the stainless steel part, the part is treated by aluminum plating using Al-10% Si after passing the helium inspection. The immersion plating parameters can be selected as 600°C, the immersion plating time is controlled to be 15s or less, and the coating thickness is 35μm. Then, a 3-5% potassium fluoroaluminate flux is sprayed, and the time above 585°C during welding is controlled to be 0.1-10min, etc.

[0145] Example 11

[0146] The difference between this example and Example 3 is that in step S21, when the heat exchange tube 1 is welded with the first tube 2, fusion welding is used for welding, and the fusion welding can be laser welding. After laser welding of the heat exchange tube 1 and the first tube 2, the heat exchange tube 1 and the fins 4 are welded.

[0147] Example 12

[0148] Based on the foregoing description, a heat exchanger as shown in FIG. 1 or 2 is made. First, the heat exchange tube 1 is coated with aluminum material on the outer surface of the heat exchange tube 1 by arc spraying, and an aluminum coating is formed on the outer surface of the heat exchange tube 1. Then, the fins 4 are placed between adjacent heat exchange tubes 1, and after assembly, the heat exchange tube 1 and the fins 4 are fixed by overall bundling with 0Cr18Ni9 stainless steel wire. After bundling, it is placed on a stainless steel bracket and placed in a continuous brazing furnace under nitrogen protection. In the brazing heating zone, a 5-20% mixed fluoroaluminate potassium and cesium fluoroaluminate flux with equal mass ratio is sprayed on the heat exchanger core to apply the flux, and then after drying at a set temperature of 200°C, it enters the brazing section of the furnace body. The highest temperature of the brazing section is set to 605°C, and the time above 585°C is 3 minutes.

[0149] The end of the heat exchange tube 1 is inserted into the first tube 2, the heat exchange tube 1 and the first tube 2 are assembled, and the connection of the heat exchange tube 1 and the first tube 2 is completed. Then, nickel-based solder is used for induction welding of the connection of the heat exchange tube 1 and the first tube 2, and after welding, the heat exchanger product is obtained.

[0150] Example 13

[0151] Based on the foregoing description, the heat exchanger as shown in FIG. 1 or 2 is made. First, a nickel coating layer is formed on the outer surface of the heat exchange tube 1 by electroless plating; then the fins 4 are placed between adjacent heat exchange tubes 1, and after assembly, the heat exchange tube 1 and the fins 4 are fixed by overall bundling with 0Cr18Ni9 stainless steel wire. After bundling, it is placed on a stainless steel bracket and placed in a nitrogen-protected continuous brazing furnace for brazing. When the heat exchanger enters the brazing heating zone, a mixed brazing agent of potassium fluoroaluminate and cesium fluoroaluminate with a concentration of 5-20% is used for spraying treatment of the heat exchanger to apply the flux. Subsequently, after passing through the drying zone with a set temperature of 200°C, it enters the brazing section of the furnace body. The highest temperature of the brazing section is set to 605°C, and the time above 590°C is 0.5 minutes.

[0152] The end of the heat exchange tube 1 is inserted into the first tube 2, the heat exchange tube 1 and the first tube 2 are assembled, the connection of the heat exchange tube 1 and the first tube 2 is completed, and then the electric arc welding is used to weld the connection of the heat exchange tube 1 and the first tube 2. After welding, the heat exchanger product is obtained.

[0153] Example 14

[0154] Based on the foregoing description, the heat exchanger as shown in FIG. 6 is made. First, an aluminum coating layer is formed on the outer surface of the heat exchange tube 1 by hot dipping plating; then the heat exchange tube 1 is inserted into the through hole of the fin 4, and after assembly, it is placed on a stainless steel bracket and placed in a nitrogen-protected continuous brazing furnace for brazing. When the heat exchanger enters the brazing heating zone, a mixed brazing agent of potassium fluoroaluminate and cesium fluoroaluminate with a concentration of 5-20% is used for spraying treatment of the heat exchanger to apply the flux. Subsequently, after passing through the drying zone with a set temperature of 200°C, it enters the brazing section of the furnace body. The highest temperature of the brazing section is set to 605°C, and the time above 590°C is 1 minute.

[0155] The end of the heat exchange tube 1 is inserted into the first tube 2, the heat exchange tube 1 and the first tube 2 are assembled, the connection of the heat exchange tube 1 and the first tube 2 is completed, and then the electric arc welding is used to weld the connection of the heat exchange tube 1 and the first tube 2. After welding, the heat exchanger product is obtained.

[0156] Comparative Example 1

[0157] The difference between this example and Example 1 is that the assembled stainless steel part of the heat exchanger is placed on a 0Cr18Ni9 tooling and placed in a vacuum brazing furnace for welding. The furnace temperature after cooling is 250°C, and the stainless steel part of the heat exchanger is obtained. Compared with Example 1, the stainless steel part of the heat exchanger in the example of the present disclosure is oxidized and discolored, which increases the difficulty of welding the heat exchange tube and the fin in the subsequent process, causing virtual welding.

[0158] Comparative Example 2

[0159] The difference between the embodiment and example 4 is that the brazing agent with a concentration of 3-10% of potassium fluoroaluminate is used to spray the heat exchanger to apply the flux, wherein, compared with the mixed brazing agent with a concentration of potassium fluoroaluminate and cesium fluoroaluminate used in example 4, in the embodiment of the present disclosure, there are more virtual welding positions at the welding positions of the heat exchange tube and the fin.

[0160] Comparative example 3

[0161] The difference between the embodiment and example 6 is that the highest temperature of the brazing section is set to 605℃, and the brazing time above 585℃ is 15 minutes, and the heat exchanger product is obtained after cooling and discharging. Compared with example 6, the time above 585℃ during the welding process is too long, a continuous brittle intermetallic compound layer is formed in the weld on one side of the heat exchange tube, so that the weld of the heat exchange tube and the fin is brittle, and there is a risk of cracking and falling under the action of temperature and pressure changes in the subsequent use of the heat exchanger.

[0162] The embodiment of the present disclosure also provides a heat exchanger, which can be made by using the heat exchanger processing method described above, and can be applied to the fields of refrigeration, heating, ventilation, air conditioning, water tank heat exchanger, etc. The heat exchanger can circulate water, refrigerant and other heat exchange media. The heat exchanger in the application embodiment will be described clearly and completely.

[0163] According to the embodiment of the second aspect of the present application, a heat exchanger 10 is provided, comprising: a plurality of heat exchange tubes 1, a first tube 2 and fins 4; wherein the material of the plurality of heat exchange tubes 1 is stainless steel; the material of the first tube 2 is stainless steel, the first tube 2 is connected with the heat exchange tube 1, and the inner cavity of the first tube 2 is in communication with the inner cavity of the heat exchange tube 1; at least part of the fin 4 is welded between two adjacent heat exchange tubes 1, and the material of the fin 4 is aluminum or aluminum alloy. The first tube 2 can be a manifold structure as shown in FIG. 1, FIG. 2 and FIG. 4, or a bent pipe structure as shown in FIG. 3. The fin 4 in the embodiment of the present disclosure can be a flat fin 4, a windowed fin 4, a corrugated fin 4, etc. The material of the heat exchange tube 1 and the first tube 2 is stainless steel, which can improve the corrosion resistance of the heat exchanger, reduce the risk of leakage of the heat exchanger, and prolong the service life of the heat exchanger; and the material of the fin 4 is aluminum or aluminum alloy, which has better heat conduction effect, thereby improving the heat exchange performance of the heat exchanger.

[0164] As shown in FIG. 2, the heat exchanger 10 comprises two first pipes 2, a plurality of heat exchange pipes 1 and a plurality of fins 4, in the heat exchanger 10, the end of the plurality of heat exchange pipes 1 is inserted into the first pipe 2 and connected with the first pipe 2, the heat exchange pipe 1 is provided with a plurality of channels for the flow of heat exchange medium, and the plurality of channels of the heat exchange pipe 1 are in communication with the inner cavity of the first pipe 2, and the fin 4 is located between the two adjacent heat exchange pipes 1. The heat exchange pipe 1 and the first pipe 2 are made of stainless steel. The first pipe 2 is provided with a fluid inlet and a fluid outlet in communication with the inner cavity thereof, so as to facilitate the fluid to enter the heat exchanger 10. In addition, the end of the first pipe 2 can be provided with an end cover, and the first pipe 2 can be provided with a partition plate inside, and the first pipe can also be connected with other pipe components such as mounting bracket, inlet and outlet pipe, etc., wherein the end cover, mounting bracket, inlet and outlet pipe can also be made of stainless steel.

[0165] The plurality of heat exchange pipes 1 are arranged along the length direction of the first pipe 2, the length direction of the first pipe 2 can refer to the Y direction in FIG. 1, and the length direction of the heat exchange pipe 1 can refer to the X direction in FIG. 2, in FIG. 2, the number of the first pipe 2 is 2, and the two ends of the length direction of the heat exchange pipe 1 are inserted into the inner cavities of the two first pipes 2. In some other embodiments, the number of the first pipe 2 can be 1 or more than 2. Correspondingly, the number of the heat exchange pipe 1 and the fin 4 is also set according to the actual product needs. In the embodiment of the present disclosure, the fin 4 is a wave-shaped structure extending along the length direction (X direction) of the heat exchange pipe 1. The heat exchanger comprises a plurality of fins 4, the fin 4 is located between the adjacent heat exchange pipes 1, and the peak or trough position of the wave-shaped structure of the fin 4 is welded and connected with the heat exchange pipe 1.

[0166] In some embodiments, as shown in FIG. 3, the plurality of heat exchange pipes 1 are arranged at intervals along the Y direction in FIG. 3, wherein the length direction of the heat exchange pipe 1 can refer to the X direction in FIG. 3, the end of the adjacent heat exchange pipe 1 is communicated through the curved first pipe 2, that is, the first pipe 2 is arranged between the ends of the adjacent heat exchange pipes 1, and the plurality of fins 4 are arranged at intervals along the X direction, and the length direction of the fin 4 can refer to the Y direction in FIG. 3. Along the length direction of the fin 4, a plurality of through grooves are arranged at intervals on the fin 4, one heat exchange pipe 1 passes through the through grooves of the plurality of fins 4, the fin 4 can be inserted into the heat exchange pipe 1 from the side of the heat exchange pipe 1, and the heat exchange pipe 1 and the fin 4 are connected by welding.

[0167] In some embodiments, as shown in FIG. 4, a plurality of heat exchange pipes 1 are arranged along the length direction of the first pipe 2, which can be referred to as the Y direction in the figure, and the first pipe 2 is a longitudinally extended tubular structure, and the length direction of the heat exchange pipe 1 can be referred to as the X direction in FIG. 4. In FIG. 4, the number of first pipes 2 is 2, and the two ends of the length direction of the heat exchange pipe 1 are respectively inserted into the inner cavities of the two first pipes 2 and are in communication with the first pipes 2. In some other embodiments, the number of first pipes 2 can be 1 or more than 2. In the embodiments of the present disclosure, a plurality of fins 4 are arranged along the X direction, and the length direction of the fin 4 can be referred to as the Y direction in FIG. 4. As shown in FIG. 5, a plurality of through grooves are arranged on the fin 4 along the length direction of the fin 4, so that the relative position of the middle part of each heat exchange pipe 1 is fixed by the through groove of the fin 4, that is, the heat exchange pipe 1 passes through the through groove of the fin 4, and the heat exchange pipe 1 and the fin 4 are fixedly connected by welding.

[0168] In some embodiments, as shown in FIG. 6, a plurality of through holes are arranged on the fin 4 along the length direction of the fin 4, and the heat exchange pipe 1 is fixed by passing through the through hole of the fin 4, that is, the heat exchange pipe 1 passes through the through hole of the fin 4, and the heat exchange pipe 1 and the fin 4 are fixedly connected by welding, and the overall structure of the heat exchanger can also be as shown in FIG. 4. When processing the heat exchanger as shown in FIG. 6, since the heat exchange pipe 1 is inserted into the through hole of the fin 4, the processing of the heat exchanger can only be completed by welding the heat exchange pipe 1 and the fin 4 first, and then welding the heat exchange pipe 1 and the header 2.

[0169] In the embodiments of the present disclosure, the heat exchange pipe 1 and the first pipe 2 of the heat exchanger 10 are made of stainless steel, which reduces the production cost compared with the heat exchange pipe 1 and the first pipe 2 made of copper, expands the applicable materials for manufacturing the heat exchanger 10, and improves the corrosion resistance of the heat exchanger 10 compared with the heat exchanger 10 made of aluminum, thereby expanding the application range of the heat exchanger. The fin 4 is made of aluminum or aluminum alloy, which has good heat conductivity and cost performance, thereby ensuring the heat exchange performance of the heat exchanger 10. The aluminum fin and the stainless steel heat exchange pipe are welded, which reduces the contact thermal resistance between the heat exchange pipe 1 and the fin 4, and further improves the heat exchange performance of the heat exchanger 10.

[0170] In some embodiments, the heat exchanger 10 further comprises a coating layer 3 arranged on at least a part of the surface of the heat exchange pipe 1, and the coating layer is arranged on the outer surface of the heat exchange pipe 1. The material of the coating layer 3 includes aluminum material or nickel material. The aluminum material can be aluminum or aluminum alloy. The nickel material can be nickel or nickel alloy, and the nickel alloy can be nickel-phosphorus alloy. As shown in FIG. 8, the coating layer 3 is arranged on the surface of the heat exchange pipe 1.

[0171] In some embodiments, the aluminum coating formed on the surface of the heat exchange tube, when the stainless steel heat exchange tube 1 and the aluminum fin are welded, becomes aluminum and aluminum material welding, reduces the formation of continuous brittle intermetallic compounds in the weld on one side of the heat exchange tube, improves the welding reliability of the heat exchange tube and the fin, reduces the risk of leakage of the heat exchanger, thereby improving the reliability of the heat exchanger and prolonging the service life of the heat exchanger. The thickness of the aluminum coating formed on the surface of the heat exchange tube is 30-150 μm. When the thickness of the aluminum coating is less than 30 μm, the thickness of the coating is insufficient to form a better joint, which will affect the welding reliability. When the thickness of the aluminum coating is greater than 150 μm, the thickness of the reaction layer formed is relatively thick, and the processing cost is increased.

[0172] In some embodiments, as shown in FIG. 9, the heat exchanger further comprises a welding portion 6 connecting the heat exchange tube 1 and the fin 4, at least part of the welding portion is formed by welding the heat exchange tube 1 and the fin 4, and after the heat exchange tube 1 and the fin 4 are welded, a plurality of welding portions are formed at the connection between the heat exchange tube 1 and the fin 4. After the aluminum coating 3 is provided on the surface of the heat exchange tube 1, the welding of the stainless steel heat exchange tube 1 and the aluminum fin 4 becomes aluminum and aluminum welding. After welding using aluminum-silicon-based solder, the welding portion 6 formed by welding the heat exchange tube 1 and the fin 4 comprises Al-Si compound, thereby reducing the risk of brittle intermetallic compounds formed in the welding portion of the heat exchange tube 1 and the fin 4, improving the welding reliability of the heat exchange tube and the fin, reducing the risk of leakage of the heat exchanger, and improving the reliability of the heat exchanger.

[0173] In some embodiments, the nickel coating formed on the surface of the heat exchange tube makes the nickel coating on the surface of the stainless steel heat exchange tube and the joint formed by the metallurgical reaction of the aluminum-silicon-based solder when the stainless steel heat exchange tube and the aluminum fin are welded much less brittle than the joint formed by the metallurgical reaction of the stainless steel and the aluminum-silicon-based solder, reduces the formation of brittle intermetallic compounds in the weld on one side of the heat exchange tube, improves the welding reliability of the heat exchange tube and the fin, reduces the risk of leakage of the heat exchanger, thereby improving the reliability of the heat exchanger and prolonging the service life of the heat exchanger. The thickness of the nickel coating formed on the surface of the heat exchange tube is 5-20 μm. When the thickness of the nickel coating is less than 5 μm, the thickness of the coating is insufficient to react with stainless steel to form a better joint, which will affect the welding reliability. When the thickness of the nickel coating is greater than 20 μm, the thickness of the reaction layer formed is relatively thick, and the processing cost is increased.

[0174] In some embodiments, as shown in FIG. 10, the heat exchanger further comprises a welding portion 6 connecting the heat exchange tube 1 and the fin 4, at least part of the welding portion 6 is formed by welding the heat exchange tube 1 and the fin 4, after the heat exchange tube 1 and the fin 4 are welded, a plurality of welding portions 6 are formed at the connection between the heat exchange tube 1 and the fin 4, after the surface of the heat exchange tube 1 is coated with a nickel coating 3 and welded using aluminum-silicon-based solder, the welding portion 6 formed by welding the heat exchange tube 1 and the fin 4 comprises an Al-Si compound 61 and an Al-Ni compound 62, wherein the nickel coating on the surface of the heat exchange tube 1 forms an Al-Ni compound on the surface of the heat exchange tube 1 after welding, the Al-Ni compound 62 is closer to the heat exchange tube 1 than the Al-Si compound 61, thereby reducing the risk of forming brittle intermetallic compounds of iron and aluminum on the side of the heat exchange tube 1, improving the welding reliability of the connection between the heat exchange tube and the fin, reducing the risk of leakage of the heat exchanger, and improving the reliability of the heat exchanger. The heat exchange tube and the fin are welded using aluminum-silicon-based solder, and the welding portion can also include an Al-Ni-Si compound.

[0175] In some specific embodiments, the material of the fin can include, in terms of mass percentage, Si: 2.0%-3.0%, Fe≤0.70%, Mn: 0.4%-1.8%, Zn≤2.0%, and also Al and unavoidable impurities. With this fin, when the fin and the heat exchange tube are welded, the amount of liquid solder of the stainless steel heat exchange tube 1 in contact with the single welding point position of the fin and the heat exchange tube is reduced, thereby reducing the thickness of the reaction layer when the fin and the heat exchange tube are welded, i.e., reducing the thickness of the brittle intermetallic compound, reducing the risk of thermal stress and cracking, and improving the welding reliability.

[0176] In some embodiments, a turbulence structure is arranged in the heat exchange tube 1; the turbulence structure and the inner wall of the heat exchange tube 1 are in an integral structure or a separate structure.

[0177] In other words, a turbulence structure 5 is arranged in the heat exchange tube 1, which is used to increase the disturbance of the heat exchange medium in the heat exchange tube 1, enhance the heat exchange effect of the heat exchange tube, and improve the heat exchange efficiency of the heat exchanger.

[0178] In some embodiments, the turbulence structure 5 and the inner wall of the heat exchange tube 1 are in an integral structure or a separate structure.

[0179] For example, a turbulence structure 5 is arranged in the heat exchange tube 1, such as adding protrusions, protrusions, threads, etc. in the tube of the heat exchange tube 1, wherein the protrusions, protrusions, threads, etc. and the inner wall of the heat exchange tube 1 are in an integral structure or a separate structure. As shown in FIG. 7, protrusions are added to the inner wall of the heat exchange tube 1, and the protrusions and the inner wall of the heat exchange tube 1 are in an integral structure. The heat exchange tube 1 in this application is made of stainless steel, and the thermal conductivity of stainless steel is significantly lower than that of copper and aluminum. This application strengthens heat transfer by adding protrusions, protrusions, threads, etc. to the inner wall of the heat exchange tube 1, further improving the heat exchange performance of the heat exchanger 10.

[0180] In some embodiments, the flow disturbance structure 5 is a separate structure from the heat exchange pipe 1, for example, a spiral flow disturbance device is added and arranged in the heat exchange pipe 1, which has the same effect as the protruding structure and enhances the heat exchange effect.

[0181] In some embodiments, the protruding structure can be added to the inner wall of the heat exchange pipe 1, and a separate flow disturbance structure can be additionally arranged to further enhance the heat exchange effect, which will not be described again.

[0182] In addition, in some embodiments, the wall thickness of the stainless steel heat exchange pipe 1 can also be thinned to achieve the purpose of ensuring the heat exchange performance of the heat exchanger 10. For example, under the condition of considering the pressure strength of the heat exchange pipe, the wall thickness of the stainless steel heat exchange pipe 1 in the embodiments of the present disclosure can be thinned by 20-50% compared with the wall thickness of the copper material heat exchange pipe 1 in the related art, thereby improving the heat exchange efficiency of the heat exchange pipe and the overall heat exchange efficiency of the heat exchanger.

[0183] In the description of the present specification, the description of the terms "one embodiment", "some embodiments", "an example", "a specific example", or "some examples" and the like means that the specific features, structures, materials or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present application. In the present specification, the illustrative description of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any appropriate manner in any one or more embodiments or examples. In addition, the person skilled in the art can combine and combine the different embodiments or examples described in the present specification and the features of the different embodiments or examples without contradiction.

[0184] The above is only some embodiments of the present application and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A method for processing a heat exchanger, wherein, Includes the following steps: Assemble the heat exchange tube and the first tube, including connecting the heat exchange tube and the first tube, wherein the heat exchange tube is made of stainless steel and the first tube is made of stainless steel. Weld the connection between the heat exchange tube and the first tube; Assembling fins and heat exchange tubes includes installing at least a portion of the fins between adjacent heat exchange tubes, wherein the fins are made of aluminum or aluminum alloy. Weld the heat exchange tube and the fins; Before welding the heat exchange tube and the fins, an aluminum or nickel material is applied to at least a portion of the surface of the heat exchange tube to form a coating.

2. The heat exchanger processing method according to claim 1, wherein, In the step of disposing the aluminum material on at least a portion of the surface of the heat exchange tube, the coating is formed by hot-dip galvanizing or arc spraying, and the thickness of the aluminum coating is 30-150 μm.

3. The heat exchanger processing method according to claim 1, wherein, In the step of depositing nickel material on at least a portion of the surface of the heat exchange tube, the coating is formed by chemical plating or electroplating, and the thickness of the nickel coating is 5-20 μm; and / or, after chemical plating or electroplating the nickel material, a heat treatment is performed in a vacuum furnace or a gas-protected furnace at 400°C for 1 hour.

4. The heat exchanger processing method according to claim 1, wherein, In the step of welding the heat exchange tube to the fins, brazing is performed using flux under gas protection, the flux including fluoroaluminate flux; When the fins contain at least 2.0% silicon, they are brazed in a gas-protected environment using flux; or, when the silicon content in the fins is less than 2.0%, they are brazed in a gas-protected environment using an aluminum-silicon based brazing filler metal and flux.

5. The heat exchanger processing method according to claim 1, wherein, In the step of welding the heat exchange tube and the fins, the time at a temperature greater than 585°C is controlled to be 0.5-10 minutes.

6. The heat exchanger processing method according to any one of claims 1-5, wherein, After welding the heat exchange tube to the first tube, weld the fins and the heat exchange tube.

7. The heat exchanger processing method according to claim 6, wherein, In the step of welding the heat exchange tube to the first tube, a nickel-based brazing filler metal is used to perform vacuum brazing on the heat exchange tube and the first tube. Alternatively, the heat exchange tube and the first tube can be brazed under gas protection using manganese-based brazing filler metal, high-copper brazing filler metal, or silver self-brazing filler metal. Alternatively, nickel-based brazing filler metal or silver brazing filler metal combined with borate fluoride flux can be used to induction braze or flame braze the heat exchange tube to the first tube.

8. The heat exchanger processing method according to claim 6 or 7, wherein, In the step of welding the heat exchange tube to the first tube, the gap at the connection between the heat exchange tube and the first tube is controlled within the range of 0.03-0.25 mm.

9. The heat exchanger processing method according to claim 6 or 7, wherein, In the step of welding the heat exchange tube and the first tube by vacuum brazing or by gas-shielded brazing, the furnace exit temperature is controlled to be less than or equal to 200°C.

10. The heat exchanger processing method according to claim 6 or 7, wherein, After welding the heat exchange tube to the first tube, a high-temperature diffusion treatment is performed after brazing.

11. The heat exchanger processing method according to claim 6 or 7, wherein, The melting temperature of the solder used to weld the heat exchange tube and the first tube is T1, and the melting temperature of the solder used to weld the heat exchange tube and the fins is T2, where T1-T2 > 100℃.

12. The heat exchanger processing method according to claim 6, wherein, In the step of welding the heat exchange tube to the first tube, the heat exchange tube and the first tube are welded by fusion welding.

13. The heat exchanger processing method according to any one of claims 1-5, wherein, In the step of welding the heat exchange tube and the fins, the heat exchange tube and the first tube are welded together by laser welding; or by arc welding; or by induction brazing with silver brazing filler metal, nickel-based brazing filler metal, or manganese-based brazing filler metal; or by flame brazing with silver brazing filler metal.

14. A heat exchanger, wherein, include: Multiple heat exchange tubes, wherein the heat exchange tubes are made of stainless steel; The first tube is made of stainless steel. The first tube is connected to the heat exchange tube, and the inner cavity of the first tube communicates with the inner cavity of the heat exchange tube; The fins are at least partially welded between two adjacent heat exchange tubes, and the fins are made of aluminum or aluminum alloy.

15. The heat exchanger according to claim 14, wherein, At least a portion of the surface of the heat exchange tube is covered with a nickel coating having a thickness of 5-20 μm; and / or, the heat exchanger further includes a welded portion connecting the heat exchange tube and the fins, the welded portion comprising an Al-Ni compound and an Al-Si compound.

16. The heat exchanger according to claim 14, wherein, At least a portion of the surface of the heat exchange tube includes an aluminum coating with a thickness of 30-150 μm; and / or, the heat exchanger further includes a welded portion connecting the heat exchange tube and the fins, the welded portion comprising an Al-Si compound.

17. The heat exchanger according to any one of claims 14-16, wherein, The heat exchange tube is provided with a turbulence-inducing structure; the turbulence-inducing structure is either an integral structure with the inner wall of the heat exchange tube or a separate structure.

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