Heat exchanger and preparation method and application thereof

Abstract

The invention discloses a heat exchanger and a preparation method and application thereof, and belongs to the technical field of heat exchange materials. The heat exchanger comprises a pipe and fins, the pipe comprises a pipe base material layer and a zinc impregnation layer arranged on the surface of the pipe base material layer, each fin comprises a fin base material layer and a solder layer arranged on the surface of the fin base material layer, and the fins are connected with the zinc impregnation layer of the pipe through the solder layers; the potential of the fin base material layer is lower than that of the solder layer, and the potential of the solder layer is lower than that of the zinc impregnation layer. By regulating and controlling the potentials of the fin base material layer, the solder layer and the zinc impregnation layer to be sequentially increased, corrosion can be preferentially generated on the fin by taking the fin as an anode and taking the pipe as a cathode on the basis of a sacrificial anode principle, so that the corrosion resistance of the pipe is improved, the corrosion leakage of the pipe is effectively reduced, the leakage of the heat exchanger is avoided, and the service life of the heat exchanger is prolonged. And the phenomenon that refrigeration or heating cannot be carried out is avoided.

Description

Technical Field

[0001] This invention relates to the field of heat exchange materials technology, and in particular to a heat exchanger, its preparation method, and its application. Background Technology

[0002] One of the core components of heat exchange equipment such as air conditioners is the heat exchanger, which is used to achieve cooling or heating functions. The performance of the heat exchanger directly affects the energy efficiency and service life of the heat exchange equipment. Among them, aluminum heat exchangers are widely used in heat exchange equipment due to their lightweight, high thermal conductivity, and good formability. However, during use, the surface of aluminum heat exchangers is easily oxidized to form a dense oxide film, which is usually at the nanometer level. In environments with high humidity, high salt, high temperature, and corrosive gases, aluminum heat exchangers have poor corrosion resistance.

[0003] To address this issue, existing technologies typically employ zinc spraying on the surface of flat tubes in aluminum heat exchangers to improve their corrosion resistance. However, current zinc spraying techniques have several drawbacks. For instance, while zinc spraying can enhance the corrosion resistance of aluminum tubes or flat tubes, the improvement is limited, and corrosion may still occur during use, affecting their service life. Furthermore, improper control during the zinc spraying process can lead to uneven zinc layer thickness, impacting the product's appearance and the stability of its corrosion resistance. Summary of the Invention

[0004] The present invention aims to solve one of the aforementioned technical problems existing in the prior art. Therefore, one objective of the present invention is to provide a heat exchanger in which the potential of the fin substrate layer, the solder layer, and the zinc-diffused layer increases sequentially, thereby giving the heat exchanger excellent corrosion resistance.

[0005] The second objective of this invention is to provide a method for preparing the above-mentioned heat exchanger.

[0006] The third objective of this invention is to provide a temperature regulating device.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] A first aspect of the present invention provides a heat exchanger including a tube and fins. The tube includes a tube substrate layer and a zinc-impregnated layer disposed on the surface of the tube substrate layer. The fins include a fin substrate layer and a solder layer disposed on the surface of the fin substrate layer. The fins are connected to the zinc-impregnated layer of the tube through the solder layer. The potential of the fin substrate layer is lower than the potential of the solder layer, and the potential of the solder layer is lower than the potential of the zinc-impregnated layer.

[0009] The heat exchanger according to the first aspect of the present invention has at least the following beneficial effects:

[0010] By adjusting the potential of the fin substrate layer, solder layer, and zinc-infiltrated layer to increase sequentially, based on the principle of sacrificial anode, the fins act as the anode and the tube as the cathode, causing corrosion to preferentially occur on the fins. This improves the corrosion resistance of the tube and effectively reduces corrosion leakage, which can lead to heat exchanger leaks and inability to cool or heat.

[0011] In some specific embodiments of the present invention, the potential of the fin substrate layer is 1 to 100 mV lower than the potential of the solder layer.

[0012] In some specific embodiments of the present invention, the potential of the solder layer is 5 to 100 mV lower than the potential of the zinc-diffused layer.

[0013] Maintaining the potential difference between the fin substrate layer and the solder layer, and between the solder layer and the zinc-plated layer, within appropriate ranges can ensure that the pipes and heat exchangers have good heat exchange performance, corrosion resistance, and service life. If the potential difference is too large, it may cause the fins to detach prematurely within their design life. Since the main function of fins in air conditioning is heat exchange, fin detachment will reduce the cooling or heating performance of the air conditioner. If the potential difference is too small, the pipes will not be effectively protected. Even if the fin structure extends the corrosion and leakage time of the pipes to some extent, it still cannot meet the requirement of no leakage within the design life of the pipes.

[0014] In other words, by adjusting the potential difference between the fin substrate layer and the solder layer, and the potential difference between the solder layer and the zinc-diffused layer, within a suitable range, this invention can, based on the principle of sacrificial anode, cause corrosion to occur preferentially on the fins, thereby obtaining a microchannel heat exchanger with good heat exchange effect, corrosion resistance, and long service life.

[0015] In some specific embodiments of the present invention, the thickness of the zinc-impregnated layer is 70–350 μm.

[0016] The thickness of the zinc-impregnated layer affects the corrosion resistance and mechanical strength of the pipe. Choosing an appropriate zinc-impregnated layer thickness ensures good corrosion resistance, leak resistance, and service life. Specifically, forming a zinc-impregnated layer of a specific thickness on the outer surface of the pipe substrate layer results in a zinc-impregnated layer with a higher potential than the solder layer. This leads to better corrosion resistance and a longer service life for the manufactured pipe (or heat exchanger). Furthermore, the specific thickness ensures both good corrosion resistance and a suitable wall thickness for pressure bearing, preventing premature leakage during long-term service. This results in pipes with excellent corrosion resistance, leak resistance, and service life, meeting the requirements of heat exchangers, especially microchannel heat exchangers.

[0017] In some specific embodiments of the present invention, the maximum zinc concentration of the zinc-impregnated layer is 0.01 to 8 wt%.

[0018] The maximum zinc concentration of the zinc-diffused layer affects the overall zinc concentration of the zinc-diffused layer and the zinc content distribution of the zinc-diffused layer, thereby affecting the potential and corrosion resistance of the zinc-diffused layer. Adjusting the maximum zinc concentration of the zinc-diffused layer within a specific range can obtain a zinc-diffused layer with a higher potential than the solder layer, which is beneficial to improving the corrosion resistance of the material.

[0019] In some specific embodiments of the present invention, the potential of the zinc-impregnated layer gradually increases from the outside to the inside.

[0020] By controlling the potential change of the zinc-coated layer, the outer surface of the zinc-coated layer is preferentially corroded over the inner surface, which effectively protects the base material layer of the pipe and improves the corrosion resistance of the pipe and heat exchanger.

[0021] In some specific embodiments of the present invention, the outer surface potential of the zinc-impregnated layer is ≤-820mV.

[0022] In some specific embodiments of the present invention, the internal surface potential of the zinc-impregnated layer is ≥-780mV.

[0023] The more negative the potential of a material, the more easily it is corroded. By controlling the outer and inner surface potentials of the zinc-dipped layer, the zinc-dipped layer corrodes preferentially over the pipe substrate layer during service, and the outer surface corrodes preferentially over the inner surface, effectively protecting the pipe substrate layer and improving the corrosion resistance of the microchannel heat exchanger. Furthermore, the potential of the zinc-dipped layer is higher than that of the solder layer and the fin substrate layer, which helps to delay the corrosion of both the zinc-dipped layer and the pipe substrate layer, thus effectively protecting the pipe material.

[0024] In some specific embodiments of the present invention, the zinc-diffused layer contains a crystalline phase, and the grain size of the crystalline phase in the zinc-diffused layer is ≤0.03μm.

[0025] The size of the grains is related to the mechanical properties and corrosion resistance of the material. Generally, the smaller the grain size, the higher the strength and the better the corrosion resistance. Controlling the grain size of the zinc-infiltrated layer to be small is beneficial to improving the strength of the zinc-infiltrated layer and also to obtaining a zinc-infiltrated layer with a higher potential than the solder layer, thereby improving the corrosion resistance of the material.

[0026] In some specific embodiments of the present invention, the material of the pipe substrate layer is aluminum alloy, and the aluminum alloy used in the pipe substrate layer includes the following alloying elements by mass percentage: Si: 0.01-0.6wt%, Fe: 0.01-0.6wt%, Mn: 0.01-1.2wt%, Ti: 0.005-0.3wt%, Cu: ≤0.1wt%, and unavoidable impurities.

[0027] The unavoidable impurities refer to impurities that cannot be completely avoided during the material production process. These impurities may originate from raw materials, processing techniques, or environmental factors. Unavoidable impurities in the pipe substrate of this invention include Zn and Cr.

[0028] In some specific embodiments of the present invention, the total impurity content in the aluminum alloy used in the tubular substrate layer is ≤0.3wt%.

[0029] In some specific embodiments of the present invention, the content of a single impurity in the aluminum alloy used in the tubular substrate layer is ≤0.1wt%.

[0030] In some specific embodiments of the present invention, the aluminum alloy used in the tubular substrate layer also includes zinc as an alloying element, and the zinc content is ≤0.3wt%.

[0031] By controlling the zinc content of the pipe substrate layer to a low level, a high self-corrosion potential is ensured, making it higher than that of the zinc-infiltrated layer. This makes the pipe less susceptible to corrosion during use, thereby extending its service life.

[0032] In some specific embodiments of the present invention, the pipe substrate layer contains a crystalline phase, and the cross-sectional shape of the crystalline phase in the pipe substrate layer includes a rectangular shape.

[0033] The shape of grains affects the corrosion resistance of materials. Grains with rectangular cross-sections exhibit more uniform growth conditions in all directions, resulting in more consistent mechanical and corrosion resistance. Furthermore, equiaxed grains generally offer the best corrosion resistance; however, existing pipe substrates are formed through extrusion processes, making it difficult to form equiaxed grains. This invention controls the formation of rectangular cross-section grains, which helps ensure that the potential of the pipe substrate layer is higher than that of the zinc-infiltrated layer, thus achieving excellent corrosion resistance.

[0034] In some specific embodiments of the present invention, the first side length of the rectangle is 0.1 to 25 mm.

[0035] In some specific embodiments of the present invention, the second side length of the rectangle is 0.1 to 7 mm.

[0036] In some specific embodiments of the present invention, the length ratio of the first side length to the second side length is 0.7 to 12.

[0037] Controlling the grain shape and size of the pipe substrate layer within a specific range can improve the mechanical properties of the pipe, help ensure that the potential of the pipe substrate layer is higher than that of the zinc-infiltrated layer, improve corrosion resistance, and also enhance the appearance quality of the pipe.

[0038] In some specific embodiments of the present invention, the zinc content of the pipe is 0.05 to 1 wt%.

[0039] The zinc content of a pipe refers to the ratio of the mass of zinc in the pipe to the total mass of the pipe. By controlling the zinc content of the pipe within a specific range, the alloy composition of the pipe and its overall performance can be controlled, ensuring that the potential of the pipe is higher than that of the fins, thus giving it both good mechanical strength and corrosion resistance.

[0040] In some specific embodiments of the present invention, the tubing is a flat tube; in some more specific embodiments, the flat tube is a microchannel flat tube. A microchannel flat tube refers to a flat-shaped tube with tiny channels inside. These tiny channels can increase the heat transfer area and improve heat transfer efficiency. Microchannel flat tubes are commonly used in heat exchangers, radiators, air conditioning systems, and other fields. By controlling the process to manufacture the tubing into microchannel flat tubes, a microchannel heat exchanger with a large heat transfer area and high heat transfer efficiency can be obtained.

[0041] In some specific embodiments of the present invention, the width of the pipe is 6 to 60 mm.

[0042] In some specific embodiments of the present invention, the height of the pipe is ≤5mm.

[0043] In some specific embodiments of the present invention, the planar wall thickness of the pipe is 0.15 to 0.45 mm.

[0044] In some specific embodiments of the present invention, the side wall thickness of the pipe is 0.01 to 1 mm.

[0045] In some specific embodiments of the present invention, the single-pipe ultimate pressure resistance value of the pipe is ≥13MPa.

[0046] The tubing of this invention can be used as a microchannel flat tube, thus making it suitable for microchannel heat exchangers and temperature control devices, especially for electrical appliances such as air conditioners and water heaters. The dimensional parameters of the microchannel flat tube can be adjusted according to specific application requirements.

[0047] In some specific embodiments of the present invention, the pipe is obtained by a method comprising the following steps: subjecting the pipe substrate to zinc spraying and zinc diffusion treatment to obtain the pipe.

[0048] In some specific embodiments of the present invention, the material of the pipe substrate is aluminum alloy.

[0049] In some specific embodiments of the present invention, the zinc application rate for the zinc spraying treatment is 1–20 g / m³. 2 .

[0050] By controlling the specific amount of zinc applied, the zinc content in the pipe can be adjusted, as well as the distribution and concentration of zinc in the zinc-infiltrated layer. This allows the material to have a suitable potential, resulting in a zinc-infiltrated layer with a higher potential than the solder layer. Consequently, the manufactured pipe exhibits good corrosion resistance and a long service life.

[0051] In some specific embodiments of the present invention, the thickness of the zinc layer formed by the zinc spraying treatment is ≤5μm.

[0052] By controlling the thickness of the zinc layer, the penetration rate and depth of zinc can be adjusted, thereby regulating the distribution and concentration of zinc in the zinc-infiltrated layer. This results in a zinc-infiltrated layer with a higher potential than the solder layer, which in turn gives the manufactured pipe good corrosion resistance and a long service life.

[0053] In some specific embodiments of the present invention, the zinc layer formed by the zinc spraying treatment covers 50% to 100% of the surface area of ​​the pipe substrate.

[0054] The coverage area of ​​the zinc layer on the surface of the pipe substrate also affects the penetration and distribution of zinc. Keeping the coverage area of ​​the zinc layer within a certain range can improve the distribution of zinc in the zinc-infiltrated layer, which is conducive to obtaining a zinc-infiltrated layer with a higher potential than the solder layer. This results in the manufactured pipe having good corrosion resistance and a long service life.

[0055] In some specific embodiments of the present invention, the voltage of the zinc spraying treatment is 15 to 35V.

[0056] In some specific embodiments of the present invention, the gas pressure of the zinc spraying treatment is 0.4 to 1 MPa.

[0057] In some specific embodiments of the present invention, the linear velocity of the zinc spraying process is 10 to 70 m / min.

[0058] In some specific embodiments of the present invention, the distance between the zinc spraying equipment used in the zinc spraying treatment and the surface of the pipe substrate is 120-180 mm.

[0059] A zinc spraying process with specific parameters is used to apply a zinc layer to the pipe substrate. After subsequent zinc diffusion treatment, metallic zinc can penetrate and distribute in the pipe, forming a zinc diffusion layer with a higher potential than the solder layer. This results in pipes with good corrosion resistance and long service life, as well as microchannel heat exchangers.

[0060] In some specific embodiments of the present invention, the temperature of the zinc diffusion treatment is 300–620°C.

[0061] In some specific embodiments of the present invention, the zinc diffusion treatment time is 1 to 30 minutes.

[0062] Zinc diffusion temperature and zinc diffusion time are key process parameters that affect the thickness of the zinc diffusion layer and have a significant impact on the distribution of zinc in the zinc diffusion layer. By using specific zinc diffusion temperature and zinc diffusion time, the zinc diffusion layer can meet the requirements of this invention, especially making the potential of the zinc diffusion layer higher than that of the solder layer, which is beneficial to obtaining pipes and heat exchangers with good corrosion resistance and long service life.

[0063] In some specific embodiments of the present invention, the pipe substrate contains a crystalline phase, and the grain size of the crystalline phase in the pipe substrate is 5 to 100 μm.

[0064] In some specific embodiments of the present invention, the pipe substrate contains impurity precipitates, the grain size of which is ≤50μm.

[0065] Controlling the grain size and impurity precipitate grain size in the pipe substrate ensures that the substrate has a suitable crystal phase structure and mechanical strength, as well as a good zinc diffusion effect. This facilitates the formation of a zinc diffusion layer with a higher potential than the solder layer, resulting in pipes and heat exchangers with good corrosion resistance and long service life.

[0066] In some specific embodiments of the present invention, the solder layer is made of aluminum alloy; the aluminum alloy used in the solder layer comprises the following alloying elements by mass percentage: Cu: 0.01-0.52 wt%; Si: 1-10 wt%; Fe: 0.1-0.8 wt%; Mn: 0.1-1.5 wt%; Mg: ≤0.5 wt%; Cr, Zr, In: Cr+Zr+In≤0.2%; and Fe+Mn≤2 wt%.

[0067] By adjusting the alloy composition of the solder layer, the potential of the solder layer can be controlled to meet the design requirements of this invention. Even if the potential of the solder layer is lower than that of the zinc-diffused layer and higher than that of the fin substrate layer, the fins will corrode preferentially over the pipe, which is beneficial to improving the corrosion resistance and service life of the pipe.

[0068] In some specific embodiments of the present invention, the fin substrate layer is made of aluminum or aluminum alloy.

[0069] By adjusting the composition of the fin substrate layer to make its potential lower than that of the solder layer, corrosion occurs preferentially before the solder layer, thus protecting the solder layer and the pipe, and improving the corrosion resistance and service life of the pipe and heat exchanger.

[0070] In some specific embodiments of the present invention, the leakage duration of the heat exchanger in the seawater acidic salt spray test is ≥1500h.

[0071] In some more specific embodiments of the present invention, when the wall thickness of the heat exchanger tube is greater than or equal to 0.25 mm and less than 0.35 mm, the leakage duration of the heat exchanger in the seawater acid salt spray test is ≥1500 h; when the wall thickness of the heat exchanger tube is greater than or equal to 0.35 mm and less than or equal to 0.45 mm, the leakage duration of the heat exchanger in the seawater acid salt spray test is ≥2000 h.

[0072] In some specific embodiments of the present invention, the heat exchanger is a microchannel heat exchanger. That is, the microchannel heat exchanger can be obtained by using a microchannel flat tube with a flat shape and tiny channels as the tube material.

[0073] In some specific embodiments of the present invention, when the planar wall thickness of the microchannel flat tube is greater than or equal to 0.25 mm and less than 0.35 mm, the seawater acid salt spray test leakage duration of the microchannel heat exchanger is ≥1500 h; when the planar wall thickness of the microchannel flat tube is greater than or equal to 0.35 mm and less than or equal to 0.45 mm, the seawater acid salt spray test leakage duration of the microchannel heat exchanger is ≥2000 h.

[0074] In some specific embodiments of the present invention, the corrosion depth of the pipe in the 1000h seawater acidic salt spray test of the heat exchanger is ≤120μm.

[0075] In some specific embodiments of the present invention, the ratio of the pipe corrosion depth to the pipe wall thickness in the 1000h seawater acidic salt spray test of the heat exchanger is ≤0.26.

[0076] The heat exchanger provided by this invention has a long leakage time and good leakage resistance in seawater acidic salt spray tests; and the corrosion depth of the pipe is small in long-term seawater acidic salt spray tests, and the ratio of pipe corrosion depth to pipe wall thickness is small, indicating that the heat exchanger has good corrosion resistance and long service life.

[0077] In some specific embodiments of the present invention, the heat exchanger is a microchannel heat exchanger. That is, the microchannel heat exchanger can be obtained by using a microchannel flat tube with a flat shape and tiny channels as the tube material.

[0078] A second aspect of the present invention provides a method for preparing a heat exchanger as described in the first aspect of the present invention, comprising the following steps: brazing the tube and the fins to obtain the heat exchanger.

[0079] The method for preparing a heat exchanger according to the second aspect of the present invention has at least the following beneficial effects:

[0080] The above-mentioned heat exchanger manufacturing method is simple and requires low equipment. A heat exchanger that meets the design requirements can be obtained through simple brazing.

[0081] In some specific embodiments of the present invention, the temperature of the brazing process is 300–620°C.

[0082] In some specific embodiments of the present invention, the brazing process takes 1 to 30 minutes.

[0083] By using specific brazing temperatures and times, the distribution of zinc in the zinc-diffused layer, the pipe substrate layer, the fin substrate layer, and the solder layer can be controlled. The zinc concentration and the potential of each layer can be adjusted so that the potential of the fin substrate layer, the solder layer, the zinc-diffused layer, and the pipe substrate layer increases sequentially, thereby making the heat exchanger meet the design requirements and have good corrosion resistance.

[0084] In some specific embodiments of the present invention, the tube is first manufactured, and then the tube is brazed to the fins.

[0085] A third aspect of the present invention provides a temperature regulating device, comprising the heat exchanger described in the first aspect of the present invention.

[0086] The temperature regulating device according to the third aspect of the present invention has at least the following beneficial effects:

[0087] By making the heat exchanger into a temperature regulating device, a good temperature regulation effect can be achieved, and the corrosion resistance of the temperature regulating device can be effectively improved, greatly extending its service life.

[0088] In some specific embodiments of the present invention, the temperature regulating device includes at least one of a refrigerator, an air conditioner, or a water heater. Attached Figure Description

[0089] Figure 1 This is a schematic diagram of the heat exchanger structure in some embodiments of the present invention.

[0090] Figure 2 This is a schematic diagram of the cross-sectional structure of a flat tube in some embodiments of the present invention.

[0091] Figure 3 This is a diagram illustrating the specific fabrication process of the heat exchanger in Embodiment 1 of the present invention.

[0092] Figure 4 The zinc concentrations of samples 1-4 at different zinc penetration depths in Examples 1-4 of the present invention.

[0093] Figure 5 The potentials of samples 1-4 at different zinc penetration depths in Examples 1-4 of the present invention are shown. Detailed Implementation

[0094] The embodiments of the present invention are described in detail below. These embodiments are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0095] A first aspect of the present invention provides a heat exchanger, such as... Figure 1 As shown, the device includes a pipe 1 and fins 2. The pipe 1 includes a pipe substrate layer 101 and a zinc-impregnated layer 102 disposed on the surface of the pipe substrate layer 101. The fins 2 include a fin substrate layer 201 and a solder layer 202 disposed on the surface of the fin substrate layer 201. The fins 2 are connected to the zinc-impregnated layer 102 of the pipe 1 through the solder layer 202. The potential of the fin substrate layer 201 is lower than the potential of the solder layer 202, and the potential of the solder layer 202 is lower than the potential of the zinc-impregnated layer 102.

[0096] By adjusting the potential of the fin substrate layer 201, solder layer 202 and zinc-diffused layer 102 to increase sequentially, based on the principle of sacrificial anode, fin 2 can act as the anode and tube 1 as the cathode, so that corrosion occurs preferentially on fin 2, thereby improving the corrosion resistance of tube 1 and effectively reducing corrosion leakage of tube 1, which would lead to heat exchanger leakage and the inability of air conditioner to cool or heat.

[0097] In addition, it should be noted that the heat exchanger of the present invention may also include other necessary components, such as manifolds, which can be made using conventional existing technology, and the present invention does not make specific limitations.

[0098] Figure 1 In the process, there is a weld zone 203 between the zinc-diffused layer 102 and the solder layer 202. The weld zone 203 is formed during the brazing process of the solder layer 202 and plays a role in strengthening the welding strength between the zinc-diffused layer 102 and the solder layer 202.

[0099] In some embodiments of the present invention, the potential of the finned substrate layer 201 is 1 to 100 mV lower than the potential of the solder layer 202; in some specific embodiments of the present invention, the potential of the finned substrate layer 201 is 3 to 80 mV lower than the potential of the solder layer 202; in some examples of the present invention, the potential of the finned substrate layer 201 is 5 to 70 mV lower than the potential of the solder layer 202; in some specific examples of the present invention, the potential of the finned substrate layer 201 is 10 to 50 mV lower than the potential of the solder layer 202; non-limiting specific examples include 15 mV, 20 mV, 25 mV, 30 mV, 35 mV, 40 mV, or 45 mV.

[0100] In some embodiments of the present invention, the potential of the solder layer 202 is 5-100 mV lower than the potential of the zinc-diffused layer 102; in some specific embodiments of the present invention, the potential of the solder layer 202 is 8-80 mV lower than the potential of the zinc-diffused layer 102; in some examples of the present invention, the potential of the solder layer 202 is 10-70 mV lower than the potential of the zinc-diffused layer 102; in some specific examples of the present invention, the potential of the solder layer 202 is 20-60 mV lower than the potential of the zinc-diffused layer 102; non-limiting specific examples include 25 mV, 30 mV, 35 mV, 40 mV, 45 mV, 50 mV, or 55 mV.

[0101] Maintaining the potential difference between the fin substrate layer 201 and the solder layer 202, and between the solder layer 202 and the zinc-diffused layer 102, within appropriate ranges can ensure that the pipes and heat exchangers have good heat exchange performance, corrosion resistance, and service life. If the potential difference is too large, it may cause the fins to detach prematurely within their design life. Since the main function of fins in air conditioning is heat exchange, fin detachment will reduce the cooling or heating performance of the air conditioner. If the potential difference is too small, the pipes will not be effectively protected. Even if the fin structure extends the corrosion leakage time of the pipes to some extent, it still cannot meet the requirement of no leakage within the design life of the pipes.

[0102] In other words, by adjusting the potential difference between the fin substrate layer 201 and the solder layer 202, and the potential difference between the solder layer 202 and the zinc-diffused layer 102 within a suitable range in the embodiments of the present invention, corrosion can preferentially occur on the fins based on the principle of sacrificial anode, thereby obtaining a microchannel heat exchanger with good heat exchange effect, corrosion resistance and long service life.

[0103] In some embodiments of the present invention, the thickness of the zinc-infiltrating layer 102 is 70–350 μm; in some specific embodiments of the present invention, the thickness of the zinc-infiltrating layer 102 is 80–300 μm; in some examples of the present invention, the thickness of the zinc-infiltrating layer 102 is 90–270 μm; in some examples of the present invention, the thickness of the zinc-infiltrating layer 102 is 100–250 μm; non-limiting specific examples include 120 μm, 150 μm, 180 μm, 200 μm, 220 μm, or 240 μm.

[0104] The thickness of the zinc-impregnated layer 102 affects the corrosion resistance and mechanical strength of the pipe. Choosing an appropriate zinc-impregnated layer 102 thickness ensures the pipe exhibits good corrosion resistance, leak resistance, and service life. Specifically, forming a zinc-impregnated layer 102 of a specific thickness on the surface of the pipe substrate layer 101 results in a zinc-impregnated layer 102 with a higher potential than the solder layer 202. This leads to the manufactured pipe (or heat exchanger) having good corrosion resistance and a long service life. Furthermore, the specific thickness ensures both good corrosion resistance and a suitable wall thickness for pressure bearing, preventing leaks before the expected lifespan during long-term service. This results in a pipe with excellent corrosion resistance, leak resistance, and service life, meeting the requirements of microchannel heat exchangers.

[0105] The thickness of the zinc-infiltrating layer 102 can be adjusted by various process parameters during the preparation process, such as zinc infiltrating temperature, zinc infiltrating time, initial surface zinc spraying amount, material of the pipe substrate and its microstructure, etc. This is related to the specific zinc-infiltrating layer preparation method and specific process parameters. The focus of this invention is to make the zinc-infiltrating layer have a higher potential than the solder layer and a lower potential than the pipe substrate layer, so that the pipe corrodes later than the fins, and the pipe substrate layer corrodes later than the zinc-infiltrating layer, thus giving the pipe a good anti-corrosion effect while ensuring the mechanical strength and service life of the pipe.

[0106] In some embodiments of the present invention, the zinc concentration of the zinc-impregnated layer 102 gradually decreases from the outside to the inside.

[0107] In some other embodiments of the present invention, the zinc concentration of the zinc-impregnated layer 102 first increases and then decreases from the outside to the inside; in some specific embodiments of the present invention, the zinc concentration of the zinc-impregnated layer 102 reaches its maximum at a distance of 10 to 100 μm from the outer surface of the zinc-impregnated layer 102, that is, from a distance of 10 to 100 μm from the outer surface of the zinc-impregnated layer 102 inward, the zinc concentration of the zinc-impregnated layer 102 gradually decreases.

[0108] In some embodiments of the present invention, the maximum zinc concentration of the zinc-infiltrating layer 102 is 0.01–8 wt%; in some specific embodiments of the present invention, the maximum zinc concentration of the zinc-infiltrating layer 102 is 0.02–4 wt%; in some examples of the present invention, the maximum zinc concentration of the zinc-infiltrating layer 102 is 0.1–3 wt%; non-limiting specific examples include 0.5 wt%, 1 wt%, 1.5 wt%, 1.8 wt%, 2 wt%, 2.2 wt%, 2.5 wt%, or 2.8 wt%.

[0109] The maximum zinc concentration of the zinc-diffused layer 102 will affect the overall zinc concentration of the zinc-diffused layer 102 and the zinc content distribution of the zinc-diffused layer 102, thereby affecting the potential and corrosion resistance of the zinc-diffused layer 102. Adjusting the maximum zinc concentration of the zinc-diffused layer 102 within a specific range can obtain a zinc-diffused layer 102 with a higher potential than the solder layer 202, which is beneficial to improving the corrosion resistance of the material.

[0110] In some specific embodiments of the present invention, the potential of the zinc-impregnated layer 102 gradually increases from the outside to the inside.

[0111] By controlling the potential change of the zinc-diffused layer 102, the outer surface of the zinc-diffused layer 102 is preferentially corroded over the inner surface, which effectively protects the pipe substrate layer 101 and improves the corrosion resistance of the pipe and heat exchanger.

[0112] The zinc concentration of the zinc-impregnated layer 102 is inversely proportional to its potential. That is, from the outside to the inside, the zinc concentration of the zinc-impregnated layer 102 generally decreases, while the potential of the zinc-impregnated layer 102 generally increases. As far as the zinc-impregnated layer 102 is concerned, its outer surface has the most negative potential and its inner surface has the most positive potential.

[0113] In some embodiments of the present invention, the external surface potential of the zinc-impregnated layer 102 is ≤-820mV; in some specific embodiments of the present invention, the external surface potential of the zinc-impregnated layer 102 is ≤-850mV; in some examples of the present invention, the external surface potential of the zinc-impregnated layer 102 is -1000 to -850mV; non-limiting specific examples include -930mV, -970mV, -900mV, -880mV, -870mV, -860mV, or -855mV.

[0114] In some embodiments of the present invention, the internal surface potential of the zinc-diffused layer 102 is ≥ -780mV; in some specific embodiments of the present invention, the internal surface potential of the zinc-diffused layer 102 is ≥ -750mV; in some examples of the present invention, the internal surface potential of the zinc-diffused layer 102 is -750 to -600mV; non-limiting specific examples include -745mV, -740mV, -730mV, -720mV, -700mV, -670mV, or -630mV.

[0115] The more negative the potential of a material, the easier it is to corrode. By adjusting the outer and inner surface potentials of the zinc-diffused layer 102, the zinc-diffused layer 102 is made to corrode preferentially over the pipe substrate layer 101 during service. At the same time, the outer surface is corroded preferentially over the inner surface, which effectively protects the pipe substrate and improves the corrosion resistance of the microchannel heat exchanger.

[0116] In some embodiments of the present invention, the zinc-diffused layer 102 contains a crystalline phase, and the grain size of the crystalline phase in the zinc-diffused layer 102 is ≤0.03μm; in some specific embodiments of the present invention, the grain size of the crystalline phase in the zinc-diffused layer 102 is ≤0.02μm; in some examples of the present invention, the grain size of the crystalline phase in the zinc-diffused layer 102 is 0.001 to 0.02μm; non-limiting specific examples include 0.005μm, 0.008μm, 0.01μm, 0.012μm, 0.015μm, or 0.018μm.

[0117] The size of the grains is related to the mechanical properties and corrosion resistance of the material. Generally, the smaller the grain size, the higher the strength and the better the corrosion resistance. Controlling the grain size of the zinc-infiltrating layer 102 to be smaller is beneficial to improving the strength of the zinc-infiltrating layer 102 and also beneficial to obtaining a zinc-infiltrating layer 102 with a higher potential than the solder layer 202, thereby improving the corrosion resistance of the material.

[0118] In some embodiments of the present invention, the material of the pipe substrate layer 101 is aluminum alloy.

[0119] In some embodiments of the present invention, the aluminum alloy used in the tubular substrate layer 101 comprises the following alloying elements by mass percentage: Si: 0.01-0.6 wt%, Fe: 0.01-0.6 wt%, Mn: 0.01-1.2 wt%, Ti: 0.005-0.3 wt%, Cu: ≤0.1 wt%, and unavoidable impurities; in some specific embodiments of the present invention, the aluminum alloy used in the tubular substrate layer 101 comprises the following alloying elements by mass percentage: Si: 0.03-0.53 wt%, Fe: 0.09-0.27 wt%, Mn: 0.38-1.13 wt%, Ti: 0.01-0.26 wt%, Cu: 0.0008-0.015 wt%, and unavoidable impurities.

[0120] Unavoidable impurities refer to impurities that cannot be completely avoided during the material production process. These impurities may originate from raw materials, processing techniques, or environmental factors. Unavoidable impurities in the pipe substrate of this invention include Zn and Cr.

[0121] In some specific examples of the present invention, the aluminum alloy used in the tubular substrate layer 101 comprises the following alloying elements in weight percentage: Si: 0.05-0.2 wt%, Fe: 0.1-0.5 wt%, Mn: 0.1-0.4 wt%, Ti: 0.01-0.02 wt%, Cu: 0.0008-0.1 wt%, Cr: 0.001-0.06 wt%, Zn: 0.02-0.09 wt%.

[0122] In some embodiments of the present invention, the total impurity content in the aluminum alloy used for the pipe substrate layer 101 is ≤0.3wt%; in some specific embodiments of the present invention, the total impurity content in the aluminum alloy used for the pipe substrate layer 101 is ≤0.15wt%; in some examples of the present invention, the total impurity content in the aluminum alloy used for the pipe substrate layer 101 is 0.001 to 0.15wt%; non-limiting specific examples include 0.005wt%, 0.01wt%, 0.05wt%, 0.1wt%, or 0.12wt%.

[0123] In some embodiments of the present invention, the content of a single impurity in the aluminum alloy used in the pipe substrate layer 101 is ≤0.1wt%; in some specific embodiments of the present invention, the content of a single impurity in the aluminum alloy used in the pipe substrate layer 101 is ≤0.08wt%; in some examples of the present invention, the content of a single impurity in the aluminum alloy used in the pipe substrate layer 101 is 0.001 to 0.05wt%; non-limiting specific examples include 0.005wt%, 0.01wt%, 0.02wt%, 0.03wt%, or 0.04wt%.

[0124] In some embodiments of the present invention, the aluminum alloy used in the pipe substrate layer 101 further includes zinc as an alloying element, and the zinc content is ≤0.3wt%. In some specific embodiments of the present invention, the aluminum alloy used in the pipe substrate layer 101 further includes zinc as an alloying element, and the zinc content is 0.001-0.1wt%. In some examples of the present invention, the aluminum alloy used in the pipe substrate layer 101 further includes zinc as an alloying element, and the zinc content is 0.002-0.09wt%. Non-limiting specific examples include 0.006wt%, 0.008wt%, 0.01wt%, 0.04wt%, 0.07wt%, and 0.08wt%, with specific ranges such as 0.006-0.008wt%, 0.04-0.07wt%, etc.

[0125] By controlling the zinc concentration of the pipe substrate layer 101 to be low, the pipe substrate layer 101 is guaranteed to have a high self-corrosion potential, making its potential higher than that of the zinc-diffused layer 102. This makes it less susceptible to corrosion during use, thereby extending the service life of the pipe.

[0126] In some embodiments of the present invention, the pipe substrate layer 101 contains a crystalline phase, and the cross-sectional shape of the grains of the crystalline phase in the pipe substrate layer 101 includes rectangular shapes. It should be noted that the rectangle here includes quasi-rectangular shapes that are close to rectangles, and the grain shape is not required to strictly conform to the requirements of a rectangle. For example, the angle of the rectangle is not strictly equal to 90°, and a certain deviation is allowed, such as within the range of 60 to 120°.

[0127] The shape of grains affects the corrosion resistance of materials. Grains with rectangular cross-sections exhibit more uniform growth conditions in all directions, resulting in more consistent mechanical and corrosion resistance properties. Furthermore, equiaxed grains generally offer the best corrosion resistance; however, existing pipe substrates are formed through extrusion processes, making it difficult to form equiaxed grains. This invention controls the formation of rectangular cross-section grains, which helps ensure that the potential of the pipe substrate layer 101 is higher than that of the zinc-impregnated layer 102, thus achieving excellent corrosion resistance.

[0128] In the crystalline phase of the pipe substrate layer, the vast majority of grains have a rectangular cross-sectional shape, while a very small number of grains have an irregular shape and are scattered around the rectangular grains.

[0129] In some embodiments of the present invention, the proportion of crystalline phase with rectangular grain cross-sectional shape in the pipe substrate layer is ≥80%; in some embodiments of the present invention, the proportion of crystalline phase with rectangular grain cross-sectional shape in the pipe substrate layer is 80-99%; in some embodiments of the present invention, the proportion of crystalline phase with rectangular grain cross-sectional shape in the pipe substrate layer is 85-97%; non-limiting specific examples include 88%, 90%, 92%, and 95%.

[0130] In some embodiments of the present invention, the first side length of the rectangle is 0.1 to 25 mm; in some specific embodiments of the present invention, the first side length of the rectangle is 0.2 to 20 mm; non-limiting specific examples include 0.5 mm, 1 mm, 4 mm, 7 mm, 10 mm, 14 mm or 17 mm.

[0131] In some embodiments of the present invention, the second side length of the rectangle is 0.1 to 7 mm; in some specific embodiments of the present invention, the second side length of the rectangle is 0.2 to 5 mm; non-limiting specific examples include 0.5 mm, 1 mm, 2 mm, 3 mm or 4 mm.

[0132] In some embodiments of the present invention, the length ratio of the first side length to the second side length is 0.7 to 12; in some specific embodiments of the present invention, the length ratio of the first side length to the second side length is 0.9 to 10; non-limiting specific examples include 1, 2, 3, 5, 7 or 9.

[0133] Controlling the grain shape and size of the pipe substrate layer 101 within a specific range can improve the mechanical properties of the pipe, and also help ensure that the potential of the pipe substrate layer 101 is higher than that of the zinc-diffused layer 102, thus improving corrosion resistance. In addition, it can also improve the appearance quality of the pipe.

[0134] In some embodiments of the present invention, the zinc content of pipe 1 is 0.05-1 wt%; in some specific embodiments of the present invention, the zinc content of pipe 1 is 0.07-0.7 wt%; in some examples of the present invention, the zinc content of pipe 1 is 0.08-0.54 wt%; non-limiting specific examples include 0.1 wt%, 0.2 wt%, 0.3 wt%, 0.4 wt%, or 0.5 wt%.

[0135] The zinc content of pipe 1 refers to the ratio of the mass of zinc in pipe 1 to the total mass of pipe 1. By controlling the zinc content of pipe 1 within a specific range, the alloy composition of pipe 1 and its comprehensive performance can be controlled, ensuring that the potential of pipe 1 is higher than that of fin 2, so that it has both good mechanical strength and corrosion resistance.

[0136] In some embodiments of the present invention, the tube 1 is a flat tube; in some specific embodiments of the present invention, the flat tube is a microchannel flat tube.

[0137] Microchannel flat tubes refer to flat tubes with tiny internal channels. These channels increase the heat transfer area and improve heat transfer efficiency. Microchannel flat tubes are commonly used in heat exchangers, radiators, and air conditioning systems. By controlling the manufacturing process to produce microchannel flat tubes, microchannel heat exchangers with large heat transfer areas and high heat transfer efficiency can be obtained.

[0138] Schematic diagrams of the cross-sectional structure of the flat tube in some embodiments of the present invention are shown below. Figure 2 As shown, the following dimensional parameters are typically included: width W, height H, planar wall thickness t1, rib thickness t2, and side end wall thickness t3.

[0139] In some embodiments of the present invention, the width W of the flat tube is 6 to 60 mm; in some specific embodiments of the present invention, the width W of the flat tube is 8 to 40 mm; in some examples of the present invention, the width W of the flat tube is 10 to 30 mm; non-limiting specific examples include 12 mm, 15 mm, 18 mm, 20 mm, 22 mm, 25 mm or 28 mm.

[0140] In some embodiments of the present invention, the height H of the flat tube is ≤ 5 mm; in some specific embodiments of the present invention, the height H of the flat tube is 1 to 5 mm; in some examples of the present invention, the height H of the flat tube is 2 to 3.5 mm; non-limiting specific examples include 2.2 mm, 2.5 mm, 2.8 mm, 3 mm or 3.2 mm.

[0141] In some embodiments of the present invention, the planar wall thickness t1 of the flat tube is 0.15 to 0.45 mm; in some specific embodiments of the present invention, the planar wall thickness t1 of the flat tube is 0.2 to 0.4 mm; in some examples of the present invention, the planar wall thickness t1 of the flat tube is 0.25 to 0.35 mm; non-limiting specific examples include 0.28 mm, 0.3 mm, or 0.32 mm.

[0142] In some embodiments of the present invention, the flat tube has a certain rib thickness t2, and the specific thickness is not required.

[0143] In some embodiments of the present invention, the side wall thickness t3 of the flat tube is 0.01 to 1 mm; in some specific embodiments of the present invention, the side wall thickness t3 of the flat tube is 0.1 to 0.9 mm; in some examples of the present invention, the side wall thickness t3 of the flat tube is 0.5 to 0.8 mm; non-limiting specific examples include 0.55 mm, 0.6 mm, 0.65 mm, 0.7 mm or 0.75 mm.

[0144] In some embodiments of the present invention, the single-tube ultimate pressure resistance value of the flat tube is ≥13MPa; in some specific embodiments of the present invention, the single-tube ultimate pressure resistance value of the flat tube is 13 to 30MPa; non-limiting specific examples include 15MPa, 20MPa, 22MPa, 25MPa or 28MPa.

[0145] The tube 1 of this invention can be used as a microchannel flat tube, thus making it suitable for microchannel heat exchangers and temperature control devices, especially for electrical appliances such as air conditioners and water heaters. The dimensional parameters of the microchannel flat tube can be adjusted according to specific application requirements.

[0146] In some embodiments of the present invention, the pipe 1 is obtained by a method comprising the following steps: subjecting the pipe substrate to zinc spraying and zinc diffusion treatment to obtain the pipe 1.

[0147] The method for preparing pipe 1 in this embodiment of the invention can produce pipes with good corrosion resistance and long service life, and the preparation process is simple and easy to implement.

[0148] In some embodiments of the present invention, the material of the tube substrate is aluminum alloy.

[0149] In some embodiments of the present invention, the zinc application rate for zinc spraying is 1–20 g / m³. 2 In some specific embodiments of the present invention, the zinc application rate for zinc spraying is 4–14 g / m³. 2 In some examples of this invention, the zinc spraying treatment uses an application rate of 8–12 g / m³ of zinc. 2 Non-limiting specific examples include 2g / m³ 2 4g / m2 6g / m 2 8g / m 2 10g / m 2 Or 12g / m 2 .

[0150] By controlling the specific amount of zinc applied, the zinc content in the pipe 1 can be adjusted, as well as the distribution and concentration of zinc in the zinc-diffused layer 102. This allows the material to have a suitable potential, resulting in a zinc-diffused layer 102 with a higher potential than the solder layer 202. Consequently, the manufactured pipe 1 exhibits good corrosion resistance and a long service life.

[0151] In some embodiments of the present invention, the thickness of the zinc layer formed by zinc spraying is ≤5μm; in some specific embodiments of the present invention, the thickness of the zinc layer formed by zinc spraying is 0.5 to 5μm; in some examples of the present invention, the thickness of the zinc layer formed by zinc spraying is 1 to 2μm; non-limiting specific examples include 1.1μm, 1.3μm, 1.5μm, 1.7μm or 1.9μm.

[0152] By controlling the thickness of the zinc layer, the penetration rate and depth of zinc can be adjusted, thereby regulating the distribution and concentration of zinc in the zinc-infiltrating layer 102. This results in a zinc-infiltrating layer 102 with a higher potential than the solder layer 202, which in turn gives the manufactured pipe 1 good corrosion resistance and a long service life.

[0153] In some embodiments of the present invention, the zinc layer formed by zinc spraying covers 50-100% of the surface area of ​​the pipe substrate; in some specific embodiments of the present invention, the zinc layer formed by zinc spraying covers 60-98% of the surface area of ​​the pipe substrate; in some examples of the present invention, the zinc layer formed by zinc spraying covers 65-95% of the surface area of ​​the pipe substrate; non-limiting specific examples include 70%, 75%, 80%, 85%, or 90%.

[0154] The coverage area of ​​the zinc layer on the surface of the pipe substrate also affects the penetration and distribution of zinc. Keeping the coverage area of ​​the zinc layer within a certain range can improve the distribution of zinc in the zinc penetration layer 102, which is conducive to obtaining a zinc penetration layer 102 with a higher potential than the solder layer 202. This results in the manufactured pipe 1 having good corrosion resistance and a long service life.

[0155] In some embodiments of the present invention, the voltage for zinc spraying is 15-35V; in some specific embodiments of the present invention, the voltage for zinc spraying is 20-30V; in some examples of the present invention, the voltage for zinc spraying is 25-30V; non-limiting specific examples include 26V, 27V, 28V or 29V.

[0156] In some embodiments of the present invention, the gas pressure for zinc spraying is 0.4–1 MPa; in some specific embodiments of the present invention, the gas pressure for zinc spraying is 0.5–0.8 MPa; in some examples of the present invention, the gas pressure for zinc spraying is 0.6–0.7 MPa; non-limiting specific examples include 0.62 MPa, 0.64 MPa, 0.66 MPa, or 0.68 MPa.

[0157] In some embodiments of the present invention, the linear velocity of the zinc spraying process is 10 to 70 m / min; in some specific embodiments of the present invention, the linear velocity of the zinc spraying process is 20 to 60 m / min; in some examples of the present invention, the linear velocity of the zinc spraying process is 20 to 40 m / min; non-limiting specific examples include 24 m / min, 27 m / min, 30 m / min, 34 m / min or 37 m / min.

[0158] In some embodiments of the present invention, the distance between the zinc spraying equipment used for zinc spraying treatment and the surface of the pipe substrate is 120-180 mm; in some specific embodiments of the present invention, the distance between the zinc spraying equipment used for zinc spraying treatment and the surface of the pipe substrate is 130-170 mm; in some examples of the present invention, the distance between the zinc spraying equipment used for zinc spraying treatment and the surface of the pipe substrate is 140-160 mm; non-limiting specific examples include 144 mm, 147 mm, 150 mm, 154 mm or 157 mm.

[0159] In some embodiments of the present invention, the zinc spraying treatment can employ conventional existing technologies, such as arc spraying zinc, electroplating, etc.

[0160] A zinc layer is applied to the pipe substrate by zinc spraying with specific process parameters, and then zinc diffusion treatment is performed to allow metallic zinc to penetrate and distribute in the pipe, forming a zinc diffusion layer 102 with a higher potential than the solder layer 202, thereby obtaining a pipe with good corrosion resistance and long service life as well as a heat exchanger.

[0161] In some embodiments of the present invention, the zinc diffusion treatment temperature is 300–620°C; in some specific embodiments of the present invention, the zinc diffusion treatment temperature is 450–615°C; in some examples of the present invention, the zinc diffusion treatment temperature is 550–610°C; non-limiting specific examples include 560°C, 570°C, 580°C, 590°C, or 600°C.

[0162] In some embodiments of the present invention, the zinc diffusion treatment time is 1 to 30 minutes; in some specific embodiments of the present invention, the zinc diffusion treatment time is 2 to 20 minutes; in some examples of the present invention, the zinc diffusion treatment time is 3 to 15 minutes; non-limiting specific examples include 5 minutes, 7 minutes, 10 minutes or 12 minutes.

[0163] Zinc diffusion temperature and zinc diffusion time are key process parameters that affect the thickness of zinc diffusion layer 102 and have a significant impact on the distribution of zinc in zinc diffusion layer. By adopting specific zinc diffusion temperature and zinc diffusion time, zinc diffusion layer 102 can meet the requirements of this invention, especially making the potential of zinc diffusion layer 102 higher than that of solder layer 202, which is beneficial to obtaining pipes and heat exchangers with good corrosion resistance and long service life.

[0164] In some embodiments of the present invention, the pipe substrate contains a crystalline phase with a grain size of 5–100 μm; in some specific embodiments of the present invention, the grain size of the crystalline phase in the pipe substrate is 15–60 μm; in some examples of the present invention, the grain size of the crystalline phase in the pipe substrate is 25–40 μm; non-limiting specific examples include 28 μm, 30 μm, 32 μm, 35 μm, or 38 μm.

[0165] In some embodiments of the present invention, the pipe substrate contains impurity precipitates with a grain size ≤ 50 μm; in some specific embodiments of the present invention, the grain size of the impurity precipitates is 0.001–50 μm; in some examples of the present invention, the grain size of the impurity precipitates is 1–8.5 μm; and in other examples of the present invention, the grain size of the impurity precipitates is 5–50 nm.

[0166] When conventional aluminum alloys are used as the tubing substrate, the grain size of the impurity precipitates ranges from 1 to 8.5 μm, and the average grain size of the impurity precipitates is 2 to 3 μm. When dispersion-strengthened aluminum is used as the tubing substrate, the grain size of the impurity precipitates ranges from 5 to 50 nm.

[0167] Controlling the grain size and impurity precipitate grain size in the pipe substrate ensures that the substrate has a suitable crystal structure and mechanical strength, as well as good zinc diffusion effect. This facilitates the formation of a zinc diffusion layer 102 with a higher potential than the solder layer 202, resulting in pipes and heat exchangers with good corrosion resistance and long service life.

[0168] In some embodiments of the present invention, the solder layer 202 is made of aluminum alloy.

[0169] In some embodiments of the present invention, the aluminum alloy used for the solder layer 202 comprises the following alloying elements in weight percentage: Cu: 0.01-0.52 wt%; Si: 1-10 wt%; Fe: 0.1-0.8 wt%; Mn: 0.1-1.5 wt%; Mg: ≤0.5 wt%; Cr, Zr, In: Cr+Zr+In≤0.2%, and Fe+Mn≤2 wt%.

[0170] In some specific embodiments of the present invention, the aluminum alloy used in the solder layer 202 comprises the following alloying elements by mass percentage: Cu: 0.03–0.52 wt%; Si: 1.00–10.00 wt%; Fe: 0.10–0.80 wt%; Mn: 0.10–1.50 wt%; Mg: ≤0.5 wt%; Cr, Zr, In: Cr+Zr+In≤0.2%, and Fe+Mn≤2.0 wt%. In some examples of the present invention, in the composition of the solder layer 202, the mass percentage of Fe+Mn is ≤1.0 wt%, the mass percentage of Mg is 0.1–0.2 wt%, and the mass percentage of Cr+Zr+In is 0.001–0.1 wt%.

[0171] In other specific embodiments of the present invention, the aluminum alloy used in the solder layer 202 comprises the following alloying elements in the following mass percentages: Cu: 0.01-0.2 wt%; Si: 2-8 wt%; Fe: 0.2-0.5 wt%; Mn: 0.2-1 wt%; Mg: ≤0.3 wt%; Cr, Zr, In: Cr+Zr+In≤0.2%, and Fe+Mn≤1.5 wt%. In some examples of the present invention, in the composition of the solder layer 202, the mass percentage of Fe+Mn is ≤1.0 wt%, the mass percentage of Mg is 0.1-0.2 wt%, and the mass percentage of Cr+Zr+In is 0.001-0.1 wt%.

[0172] By adjusting the alloy composition of the solder layer 202, the potential of the solder layer 202 can be adjusted to meet the design requirements of the present invention. Even if the potential of the solder layer 202 is lower than that of the zinc-diffused layer 102 and higher than that of the fin substrate layer 201, the fins will corrode preferentially over the pipe, which is beneficial to improving the corrosion resistance and service life of the pipe.

[0173] In some specific embodiments of the present invention, the fin substrate layer 201 is made of aluminum or aluminum alloy.

[0174] The composition of the fin substrate layer 201 is adjusted so that its potential is lower than that of the solder layer 202, thereby causing it to corrode preferentially over the solder layer 202. This protects the solder layer 202 and the pipe 1, and improves the corrosion resistance and service life of the pipe and the heat exchanger.

[0175] In some embodiments of the present invention, the leakage duration of the heat exchanger in the seawater acid salt spray test is ≥1500h; in other embodiments of the present invention, the leakage duration of the heat exchanger in the seawater acid salt spray test is ≥2000h.

[0176] In some embodiments of the present invention, when the wall thickness of the heat exchanger tube is greater than or equal to 0.25 mm and less than 0.35 mm, the leakage duration of the seawater acid salt spray test of the heat exchanger is ≥1500 h; when the wall thickness of the heat exchanger tube is greater than or equal to and 0.35 mm and less than or equal to 0.45 mm, the leakage duration of the seawater acid salt spray test of the heat exchanger is ≥2000 h.

[0177] In some embodiments of the present invention, the heat exchanger is a microchannel heat exchanger. That is, the above-mentioned microchannel heat exchanger can be obtained by using a microchannel flat tube with a flat shape and tiny channels as the tube material.

[0178] When the heat exchanger is a microchannel heat exchanger, the tubing used is microchannel flat tube, and the tube wall thickness refers to the planar wall thickness of the microchannel flat tube. In some embodiments of the present invention, when the planar wall thickness of the microchannel flat tube is greater than or equal to 0.25 mm and less than 0.35 mm, the seawater acidic salt spray test leakage duration of the microchannel heat exchanger is ≥1500 h; when the planar wall thickness of the microchannel flat tube is greater than or equal to and less than or equal to 0.35 mm and less than or equal to 0.45 mm, the seawater acidic salt spray test leakage duration of the microchannel heat exchanger is ≥2000 h; in some specific embodiments of the present invention, when the planar wall thickness of the microchannel flat tube is greater than or equal to 0.25 mm and less than 0.35 mm, the seawater acidic salt spray test leakage duration of the microchannel heat exchanger is ≥1600 h. h; When the planar wall thickness of the microchannel flat tube is greater than or equal to and less than or equal to 0.35 mm and less than or equal to 0.45 mm, the seawater acid salt spray test leakage time of the microchannel heat exchanger is ≥2100 h; In some examples of the present invention, when the planar wall thickness of the microchannel flat tube is greater than or equal to 0.25 mm and less than 0.35 mm, the seawater acid salt spray test leakage time of the microchannel heat exchanger is 1600 to 2300 h; when the planar wall thickness of the microchannel flat tube is greater than or equal to and less than or equal to 0.35 mm and less than or equal to 0.45 mm, the seawater acid salt spray test leakage time of the microchannel heat exchanger is 2100 to 2800 h. Non-limiting specific examples include, for instance, when the planar wall thickness of the microchannel flat tube is 0.25 mm, the seawater acid salt spray test leakage duration of the microchannel heat exchanger is 1700 h, 1800 h, 1900 h, 2000 h, 2100 h, or 2200 h; and when the planar wall thickness of the microchannel flat tube is 0.35 mm, the seawater acid salt spray test leakage duration of the microchannel heat exchanger is 2200 h, 2300 h, 2400 h, 2500 h, 2600 h, or 2700 h.

[0179] In some embodiments of the present invention, the pipe corrosion depth of the heat exchanger in a 1000-hour seawater acidic salt spray test is ≤120 μm; in some specific embodiments of the present invention, the pipe corrosion depth of the heat exchanger in a 1000-hour seawater acidic salt spray test is ≤112 μm; in some examples of the present invention, the pipe corrosion depth of the heat exchanger in a 1000-hour seawater acidic salt spray test is ≤100 μm; non-limiting specific examples include 90 μm, 80 μm, 70 μm, 60 μm, 50 μm, 40 μm, 30 μm, 20 μm, or 10 μm.

[0180] In some embodiments of the present invention, the ratio of the pipe corrosion depth to the pipe wall thickness in a 1000-hour seawater acidic salt spray test of the heat exchanger is ≤0.26; in some specific embodiments of the present invention, the ratio of the pipe corrosion depth to the pipe wall thickness in a 1000-hour seawater acidic salt spray test of the heat exchanger is ≤0.25; in some examples of the present invention, the ratio of the pipe corrosion depth to the pipe wall thickness in a 1000-hour seawater acidic salt spray test of the heat exchanger is ≤0.2; non-limiting specific examples include 0.18, 0.16, 0.14, 0.12, or 0.1.

[0181] The heat exchanger provided by this invention has a long leakage time and good leakage resistance in seawater acidic salt spray tests; and the corrosion depth of the pipe is small in long-term seawater acidic salt spray tests, and the ratio of pipe corrosion depth to pipe wall thickness is small, indicating that the heat exchanger has good corrosion resistance and long service life.

[0182] A second aspect of the present invention provides a method for preparing a microchannel heat exchanger as described in the first aspect of the present invention, comprising the following steps: brazing tubes and fins to obtain a microchannel heat exchanger.

[0183] The above-mentioned method for preparing microchannel heat exchangers is simple and requires low-level equipment. Microchannel heat exchangers that meet design requirements can be obtained through simple brazing.

[0184] In some embodiments of the present invention, the brazing temperature is 300–620°C; in some specific embodiments of the present invention, the brazing temperature is 450–615°C; in some examples of the present invention, the brazing temperature is 550–610°C; non-limiting specific examples include 560°C, 570°C, 580°C, 590°C, or 600°C.

[0185] In some embodiments of the present invention, the brazing time is 1 to 30 minutes; in some specific embodiments of the present invention, the brazing time is 2 to 20 minutes; in some examples of the present invention, the brazing time is 3 to 15 minutes; non-limiting specific examples include 5 minutes, 7 minutes, 10 minutes or 12 minutes.

[0186] By using specific brazing temperatures and brazing times, the distribution of zinc in the zinc-diffused layer 102, the pipe substrate layer 101, the fin substrate layer 201, and the solder layer 202 can be controlled, thereby regulating the zinc concentration and the potential of each layer. This results in the potential of the fin substrate layer 201, the solder layer 202, the zinc-diffused layer 102, and the pipe substrate layer 101 increasing sequentially, thus ensuring that the heat exchanger meets the design requirements and has good corrosion resistance.

[0187] A third aspect of the present invention provides a temperature regulating device, including the heat exchanger of the first aspect of the present invention.

[0188] By making the heat exchanger into a temperature regulating device, a good temperature regulation effect can be achieved, and the corrosion resistance of the temperature regulating device can be effectively improved, greatly extending its service life.

[0189] In some embodiments of the present invention, the temperature regulating device includes at least one of a refrigerator, an air conditioner, or a water heater.

[0190] The following specific embodiments further illustrate the content of the present invention in detail. It should also be understood that the following embodiments are only for further explanation of the present invention and should not be construed as limiting the scope of protection of the present invention. Non-essential improvements and adjustments made by those skilled in the art based on the principles described in the present invention are all within the scope of protection of the present invention. The specific process parameters, etc., in the following examples are merely examples within a suitable range; that is, those skilled in the art can make selections within a suitable range based on the description herein, and are not intended to be limited to the specific data in the examples below. Unless otherwise specified, the raw materials, reagents, or apparatus used in the following embodiments can be obtained from conventional commercial channels or by existing known methods.

[0191] Example 1

[0192] A microchannel heat exchanger includes a tube 1 and fins 2. The tube 1 includes a tube substrate layer 101 and a zinc-impregnated layer 102 disposed on the surface of the tube substrate layer 101. The fins 2 include a fin substrate layer 201 and a solder layer 202 disposed on the surface of the fin substrate layer 201. The fins 2 are connected to the zinc-impregnated layer 102 of the tube 1 through the solder layer 202. The potential (Efin substrate layer 201) of the fin substrate layer 201 is lower than that of the solder layer 202. The potential of 02 (E solder layer 202) is lower than the potential of zinc-impregnated layer 102 (E zinc-impregnated layer 102), that is, the following relationship exists: E fin substrate layer 201 < E solder layer 202 < E zinc-impregnated layer 102. More specifically, the following relationship exists: E solder layer 202 - E fin substrate layer 201 = 12mV, E zinc-impregnated layer 102 - E solder layer 202 = 28mV.

[0193] The specific fabrication process of the microchannel heat exchanger in this example is shown in the diagram below. Figure 3 As shown, the specific preparation steps include the following:

[0194] (1) Preparation of pipe 1:

[0195] 1) Zinc spraying treatment: An aluminum alloy used as the substrate for the pipe is selected. The alloying element composition of this aluminum alloy is as follows: Si: 0.0758 wt%, Fe: 0.3730 wt%, Mn: 0.3460 wt%, Ti: 0.0194 wt%, Cu: 0.0540 wt%, Cr: 0.0013 wt%, Zn: 0.0511 wt%. This aluminum alloy contains crystalline phases with grain sizes ranging from 10.5 to 50.3 μm, and an average grain size of approximately 32.8 μm; it also contains impurity precipitates with grain sizes ranging from 2.5 to 30.2 μm, and an average grain size of 2.5 μm. The aluminum alloy is then extruded to form a shape with a microchannel structure, specifically as shown in the figure. Figure 2 The flat tube has a wall thickness t1 of 0.25 mm, a width W of 10–30 mm, a height H of 2–3.5 mm, and a side end wall thickness t3 of 0.5–0.8 mm. The single-tube ultimate pressure resistance is 13 MPa. Zinc is sprayed onto the outer surface of the flat tube substrate with a specific shape using a zinc spraying process. The zinc spraying process uses a voltage of 25–30 V, an air pressure of 0.6–0.7 MPa, a line speed of 20–40 m / min, and a distance of 140–160 mm from the spray gun to the tube, forming a zinc layer. The zinc spraying amount is 4 ± 2 g / m. 2 The zinc layer is 1.02 μm thick, and the zinc layer covers 69% of the outer surface of the pipe substrate.

[0196] 2) Zinc diffusion treatment: The pipe substrate after zinc spraying in step 1) is subjected to zinc diffusion treatment. The zinc diffusion treatment temperature is 550~610℃ and the zinc diffusion treatment time is 2~15min, resulting in pipe 1, which is denoted as sample 1.

[0197] (2) Preparation of fin 2:

[0198] Solder layers 202 are prepared on both outer surfaces of the fin substrate to obtain fin 2 composed of fin substrate layer 201 and solder layer 202. The solder layer 202 is made of aluminum alloy with the following composition: Cu: 0.01-0.2 wt%; Si: 2-8 wt%; Fe: 0.2-0.5 wt%; Mn: 0.2-1 wt%; Mg: 0.1-0.2 wt%; Cr, Zr, In: Cr+Zr+In=0.001-0.1 wt%, and Fe+Mn≤1 wt%. The fin substrate layer 201 is made of aluminum alloy.

[0199] (3) Brazing treatment:

[0200] The tube 1 (sample 1) obtained in step (1) is brazed with the fin 2 obtained in step (2). The solder layer 202 in the fin 2 and the zinc-impregnated layer 102 in the tube 1 are reinforced by a flat weld (weld area 203) to obtain the microchannel heat exchanger.

[0201] Example 2

[0202] A microchannel heat exchanger includes a tube 1 and fins 2. The tube 1 includes a tube substrate layer 101 and a zinc-impregnated layer 102 disposed on the surface of the tube substrate layer 101. The fins 2 include a fin substrate layer 201 and a solder layer 202 disposed on the surface of the fin substrate layer 201. The fins 2 are connected to the zinc-impregnated layer 102 of the tube 1 through the solder layer 202. The potential (Efin substrate layer 201) of the fin substrate layer 201 is lower than that of the solder layer 202. The potential of 02 (E solder layer 202) is lower than the potential of zinc-impregnated layer 102 (E zinc-impregnated layer 102), that is, the following relationship exists: E fin substrate layer 201 < E solder layer 202 < E zinc-impregnated layer 102. More specifically, the following relationship exists: E solder layer 202 - E fin substrate layer 201 = 29mV, E zinc-impregnated layer 102 - E solder layer 202 = 42mV.

[0203] The microchannel heat exchanger in this example specifically includes the following preparation steps:

[0204] (1) Preparation of pipe 1:

[0205] 1) Zinc spraying treatment: An aluminum alloy used as the substrate for the pipe is selected. The alloying element composition of this aluminum alloy is as follows: Si: 0.1250 wt%, Fe: 0.4570 wt%, Mn: 0.3790 wt%, Ti: 0.0160 wt%, Cu: 0.0940 wt%, Cr: 0.0050 wt%, Zn: 0.0219 wt%. This aluminum alloy contains crystalline phases with grain sizes ranging from 12.6 to 56.9 μm, and an average grain size of approximately 32.8 μm; it also contains impurity precipitates with grain sizes ranging from 1.1 to 35.7 μm, and an average grain size of 3.2 μm. The aluminum alloy is then extruded to form a shape with a microchannel structure, specifically as shown in the figure. Figure 2 The flat tube has a wall thickness t1 of 0.25 mm, a width W of 10–30 mm, a height H of 2–3.5 mm, and a side end wall thickness t3 of 0.5–0.8 mm. The single-tube ultimate pressure resistance is 13 MPa. Zinc is sprayed onto the outer surface of the flat tube substrate with a specific shape using a zinc spraying process. The zinc spraying process uses a voltage of 25–30 V, an air pressure of 0.6–0.7 MPa, a line speed of 20–40 m / min, and a distance of 140–160 mm from the spray gun to the tube, forming a zinc layer. The zinc spraying amount is 6 ± 2 g / m. 2The zinc layer is 1.10 μm thick, and the zinc layer covers 72% of the outer surface of the pipe substrate.

[0206] 2) Zinc diffusion treatment: The pipe substrate after zinc spraying in step 1) is subjected to zinc diffusion treatment. The zinc diffusion treatment temperature is 550~610℃ and the zinc diffusion treatment time is 2~15min, resulting in pipe 1, which is designated as sample 2.

[0207] (2) Preparation of fin 2:

[0208] Solder layers 202 are prepared on both outer surfaces of the fin substrate to obtain fin 2 composed of fin substrate layer 201 and solder layer 202. The solder layer 202 is made of aluminum alloy with the following composition: Cu: 0.01-0.2 wt%; Si: 2-8 wt%; Fe: 0.2-0.5 wt%; Mn: 0.2-1 wt%; Mg: 0.1-0.2 wt%; Cr, Zr, In: Cr+Zr+In=0.001-0.1 wt%, and Fe+Mn≤1 wt%. The fin substrate layer 201 is made of aluminum alloy.

[0209] (3) Brazing treatment:

[0210] The tube 1 (sample 2) obtained in step (1) is brazed with the fin 2 obtained in step (2). The solder layer 202 in the fin 2 and the zinc-impregnated layer 102 in the tube 1 are reinforced by a flat weld (weld area 203) to obtain the microchannel heat exchanger.

[0211] Example 3

[0212] A microchannel heat exchanger includes a tube 1 and fins 2. The tube 1 includes a tube substrate layer 101 and a zinc-impregnated layer 102 disposed on the surface of the tube substrate layer 101. The fins 2 include a fin substrate layer 201 and a solder layer 202 disposed on the surface of the fin substrate layer 201. The fins 2 are connected to the zinc-impregnated layer 102 of the tube 1 through the solder layer 202. The potential (Efin substrate layer 201) of the fin substrate layer 201 is lower than that of the solder layer 202. The potential of 02 (E solder layer 202) is lower than the potential of zinc-impregnated layer 102 (E zinc-impregnated layer 102), that is, the following relationship exists: E fin substrate layer 201 < E solder layer 202 < E zinc-impregnated layer 102. More specifically, the following relationship exists: E solder layer 202 - E fin substrate layer 201 = 35mV, E zinc-impregnated layer 102 - E solder layer 202 = 53mV.

[0213] The microchannel heat exchanger in this example specifically includes the following preparation steps:

[0214] (1) Preparation of pipe 1:

[0215] 1) Zinc spraying treatment: An aluminum alloy used as the substrate for the pipe is selected. The alloying element composition of this aluminum alloy is as follows: Si: 0.0991 wt%, Fe: 0.1100 wt%, Mn: 0.1150 wt%, Ti: 0.0190 wt%, Cu: 0.0081 wt%, Cr: 0.0014 wt%, Zn: 0.0840 wt%. The grain size of this aluminum alloy ranges from 13.6 to 60.9 μm, with an average grain size of approximately 32.8 μm. The aluminum alloy also contains impurity precipitates with a size range of 1.5 to 40.3 μm and an average size of 4.3 μm. The aluminum alloy is then extruded to form a shape with a microchannel structure, specifically as shown in the figure. Figure 2 The flat tube has a wall thickness t1 of 0.25 mm, a width W of 10–30 mm, a height H of 2–3.5 mm, and a side end wall thickness t3 of 0.5–0.8 mm. The single-tube ultimate pressure resistance is 13 MPa. Zinc is sprayed onto the outer surface of the flat tube substrate with a specific shape using a zinc spraying process. The zinc spraying process uses a voltage of 25–30 V, an air pressure of 0.6–0.7 MPa, a line speed of 20–40 m / min, and a distance of 140–160 mm from the spray gun to the tube, forming a zinc layer. The zinc spraying amount is 8 ± 2 g / m. 2 The zinc layer is 1.26 μm thick, and the zinc layer covers 86% of the outer surface of the pipe substrate.

[0216] 2) Zinc diffusion treatment: The pipe substrate after zinc spraying in step 1) is subjected to zinc diffusion treatment. The zinc diffusion treatment temperature is 550~610℃ and the zinc diffusion treatment time is 2~15min, resulting in pipe 1, which is designated as sample 3.

[0217] (2) Preparation of fin 2:

[0218] Solder layers 202 are prepared on both outer surfaces of the fin substrate to obtain fin 2 composed of fin substrate layer 201 and solder layer 202. The solder layer 202 is made of aluminum alloy with the following composition: Cu: 0.01-0.2 wt%; Si: 2-8 wt%; Fe: 0.2-0.5 wt%; Mn: 0.2-1 wt%; Mg: 0.1-0.2 wt%; Cr, Zr, In: Cr+Zr+In=0.001-0.1 wt%, and Fe+Mn≤1 wt%. The fin substrate layer 201 is made of aluminum alloy.

[0219] (3) Brazing treatment:

[0220] The tube 1 (sample 3) obtained in step (1) is brazed with the fin 2 obtained in step (2). The solder layer 202 in the fin 2 and the zinc-impregnated layer 102 in the tube 1 are connected to each other through a flat weld (weld area 203) to obtain the microchannel heat exchanger.

[0221] Example 4

[0222] A microchannel heat exchanger includes a tube 1 and fins 2. The tube 1 includes a tube substrate layer 101 and a zinc-impregnated layer 102 disposed on the surface of the tube substrate layer 101. The fins 2 include a fin substrate layer 201 and a solder layer 202 disposed on the surface of the fin substrate layer 201. The fins 2 are connected to the zinc-impregnated layer 102 of the tube 1 through the solder layer 202. The potential (Efin substrate layer 201) of the fin substrate layer 201 is lower than that of the solder layer 202. The potential of 02 (E solder layer 202) is lower than the potential of zinc-impregnated layer 102 (E zinc-impregnated layer 102), that is, the following relationship exists: E fin substrate layer 201 < E solder layer 202 < E zinc-impregnated layer 102. More specifically, the following relationship exists: E solder layer 202 - E fin substrate layer 201 = 42mV, E zinc-impregnated layer 102 - E solder layer 202 = 58mV.

[0223] The microchannel heat exchanger in this example specifically includes the following preparation steps:

[0224] (1) Preparation of pipe 1:

[0225] 1) Zinc spraying treatment: An aluminum alloy used as the substrate for the pipe is selected. The alloying element composition of this aluminum alloy is as follows: Si: 0.1600 wt%, Fe: 0.2800 wt%, Mn: 0.3200 wt%, Ti: 0.0170 wt%, Cu: 0.0160 wt%, Cr: 0.0013 wt%, Zn: 0.0529 wt%. The grain size of this aluminum alloy ranges from 18.6 to 65.4 μm, with an average grain size of approximately 32.8 μm. The aluminum alloy also contains impurity precipitates with a size range of 2.0 to 45.3 μm and an average size of 5.3 μm. The aluminum alloy is then extruded to form a shape with a microchannel structure, specifically as shown in the figure. Figure 2 The flat tube has a wall thickness t1 of 0.25 mm, a width W of 10–30 mm, a height H of 2–3.5 mm, and a side end wall thickness t3 of 0.5–0.8 mm. The single-tube ultimate pressure resistance is 13 MPa. Zinc is sprayed onto the outer surface of the flat tube substrate with a specific shape using a zinc spraying process. The zinc spraying process uses a voltage of 25–30 V, an air pressure of 0.6–0.7 MPa, a line speed of 20–40 m / min, and a distance of 140–160 mm from the spray gun to the tube, forming a zinc layer. The zinc spraying amount is 10 ± 2 g / m. 2 The zinc layer is 1.56 μm thick, and the zinc layer covers 92% of the outer surface of the pipe substrate.

[0226] 2) Zinc diffusion treatment: The pipe substrate after zinc spraying in step 1) is subjected to zinc diffusion treatment. The zinc diffusion treatment temperature is 550~610℃ and the zinc diffusion treatment time is 2~15min, resulting in pipe 1, which is designated as sample 4.

[0227] (2) Preparation of fin 2:

[0228] Solder layers 202 are prepared on both outer surfaces of the fin substrate to obtain fin 2 composed of fin substrate layer 201 and solder layer 202. The solder layer 202 is made of aluminum alloy with the following composition: Cu: 0.01-0.2 wt%; Si: 2-8 wt%; Fe: 0.2-0.5 wt%; Mn: 0.2-1 wt%; Mg: 0.1-0.2 wt%; Cr, Zr, In: Cr+Zr+In=0.001-0.1 wt%, and Fe+Mn≤1 wt%. The fin substrate layer 201 is made of aluminum alloy.

[0229] (3) Brazing treatment:

[0230] The tube 1 (sample 4) obtained in step (1) is brazed with the fin 2 obtained in step (2). The solder layer 202 in the fin 2 and the zinc-impregnated layer 102 in the tube 1 are connected to each other through a flat weld (weld area 203) to obtain the microchannel heat exchanger.

[0231] Performance testing

[0232] (1) The zinc concentration and potential of the pipes 1 (samples 1-4) prepared in Examples 1-4 at different zinc penetration depths were tested, and the results are as follows: Figure 4 and Figure 5 As shown, Figure 4 The zinc concentrations of samples 1-4 at different zinc penetration depths in Examples 1-4 of this invention are shown. Figure 5 This refers to the potential of samples 1-4 in Examples 1-4 of the present invention at different zinc penetration depths. From... Figure 4 It can be seen that the zinc concentration of samples 1–4 first increases and then decreases. Within the zinc penetration depth range of 10–100 μm, zinc-penetrated layer 102 has the highest zinc concentration. When the zinc penetration depth is above 250 μm, the zinc concentration remains basically stable. Figure 5 It can be seen that the potential of the outer surface of the zinc-impregnated layer 102 in samples 1-4 is the most negative (≤-850mV). From the outside to the inside, the potential of the zinc-impregnated layer 102 gradually increases, with the highest potential ≥-750mV.

[0233] (2) Corrosion resistance test: The microchannel heat exchangers prepared in Examples 1 to 4 were subjected to seawater acid salt spray (SWAAT) test according to Appendix A3 of ASTM / G85-2019. The results are shown in Table 1.

[0234] Table 1. SWAAT test results of microchannel heat exchangers in Examples 1-4

[0235]

[0236]

[0237] As can be seen from Table 1, the microchannel heat exchangers of Examples 1 to 4, with a flat tube wall thickness of 0.25 to 0.35 mm, all had a SWAAT leakage time of more than 1500 h, a corrosion depth of less than 60 μm after 1000 h, and a corrosion depth to flat wall thickness ratio of less than 0.2, demonstrating good corrosion resistance and service life.

[0238] In this embodiment of the invention, by adjusting the potential of the fin substrate layer 201, the solder layer 202 and the zinc-diffused layer 102 to increase sequentially, based on the principle of sacrificial anode, the fin 2 acts as the anode and the tube 1 acts as the cathode, so that corrosion occurs preferentially on the fin 2, thereby improving the corrosion resistance of the tube 1 and effectively reducing the occurrence of corrosion leakage in the tube 1, which would lead to heat exchanger leakage and the inability of the air conditioner to cool or heat.

[0239] Furthermore, by adjusting the potential difference among the fin substrate layer 201, the solder layer 202, and the zinc-diffused layer 102 to a suitable range, the pipe and heat exchanger can achieve better heat exchange performance, corrosion resistance, and service life. If the potential difference is too large, the fins may detach prematurely within their design life. Since the main function of fins in air conditioning is heat exchange, fin detachment will reduce the cooling or heating performance of the air conditioner. If the potential difference is too small, the pipe will not be effectively protected. Even if the fin structure extends the corrosion and leakage time of the pipe to some extent, it still cannot meet the requirement of no leakage within the design life of the pipe.

[0240] In addition, in this embodiment of the invention, a zinc-diffused layer 102 with specific thickness, specific zinc concentration, specific potential distribution and specific grain structure is prepared by using specific process parameters. Together with the pipe substrate layer 101, it constitutes a pipe 1 with good mechanical strength and corrosion resistance. When the pipe 1 is combined with the fins 2, the resulting microchannel heat exchanger has good corrosion resistance, mechanical strength and service life. After being made into a temperature regulating device, it can achieve good temperature regulation effect and can effectively improve the corrosion resistance of the temperature regulating device and greatly extend its service life.

[0241] The method provided in this invention can effectively improve the corrosion resistance of aluminum heat exchangers for air conditioners, thereby extending the service life of air conditioning equipment and meeting market demands for efficient and durable air conditioning devices. Furthermore, by surface zinc spraying of the aluminum tubing, the appearance and performance of the product can be improved, meeting market demands for high-quality air conditioning equipment. In addition, the present invention uses environmentally friendly spraying materials in the processing, conforming to current societal requirements for environmental protection and meeting market demands for green products. Therefore, the tubing and microchannel heat exchanger provided by this invention have wide applications in the manufacture of high-performance temperature control devices (such as refrigerators, air conditioners, or water heaters).

[0242] In summary, this invention, by sequentially increasing the potentials of the finned substrate layer, solder layer, and zinc-infiltrated layer, utilizes the sacrificial anode principle, with the fins acting as the anode and the tube as the cathode. This causes corrosion to preferentially occur on the fins, thereby improving the corrosion resistance of the tube and effectively reducing corrosion leakage, which can lead to heat exchanger leaks and inability to cool or heat. Furthermore, by controlling the potential difference among the finned substrate layer, solder layer, and zinc-infiltrated layer within a suitable range, the sacrificial anode principle can be applied, again with the fins acting as the anode and the tube as the cathode. This again prioritizes corrosion on the fins, improving the corrosion resistance of the tube and effectively reducing corrosion leakage. The result is a microchannel heat exchanger with excellent heat exchange performance, corrosion resistance, and long service life, which has wide applications in the manufacture of temperature control devices.

Claims

1. A heat exchanger, characterized in that, The device includes a pipe and fins. The pipe includes a pipe substrate layer and a zinc-impregnated layer disposed on the surface of the pipe substrate layer. The fins include a fin substrate layer and a solder layer disposed on the surface of the fin substrate layer. The fins are connected to the zinc-impregnated layer of the pipe through the solder layer. The potential of the fin substrate layer is lower than the potential of the solder layer, and the potential of the solder layer is lower than the potential of the zinc-impregnated layer.

2. The heat exchanger according to claim 1, characterized in that, The potential of the fin substrate layer is 1 to 100 mV lower than that of the solder layer.

3. The heat exchanger according to claim 1, characterized in that, The potential of the solder layer is 5 to 100 mV lower than that of the zinc-dipped layer.

4. The heat exchanger according to claim 1, characterized in that, The thickness of the zinc-impregnated layer is 70–350 μm.

5. The heat exchanger according to claim 1, characterized in that, The maximum zinc concentration of the zinc-impregnated layer is 0.01–8 wt%.

6. The heat exchanger according to claim 1, characterized in that, The potential of the zinc-impregnated layer gradually increases from the outside to the inside.

7. The heat exchanger according to claim 6, characterized in that, The surface potential of the zinc-impregnated layer is ≤-820mV.

8. The heat exchanger according to claim 6, characterized in that, The inner surface potential of the zinc-impregnated layer is ≥-780mV.

9. The heat exchanger according to claim 1, characterized in that, The zinc-diffused layer contains a crystalline phase, and the grain size of the crystalline phase in the zinc-diffused layer is ≤0.03μm.

10. The heat exchanger according to claim 1, characterized in that, The material of the pipe substrate layer is aluminum alloy, and the aluminum alloy used in the pipe substrate layer includes the following alloying elements by mass percentage: Si: 0.01-0.6wt%, Fe: 0.01-0.6wt%, Mn: 0.01-1.2wt%, Ti: 0.005-0.3wt%, Cu: ≤0.1wt%, and unavoidable impurities.

11. The heat exchanger according to claim 10, characterized in that, The total impurity content in the aluminum alloy used in the substrate layer of the pipe is ≤0.3wt%. And / or, the content of a single impurity in the aluminum alloy used in the tubular substrate layer is ≤0.1wt%.

12. The heat exchanger according to claim 10, characterized in that, The aluminum alloy used in the substrate layer of the pipe also contains zinc, and the zinc content is ≤0.3wt%.

13. The heat exchanger according to claim 1, characterized in that, The pipe substrate layer contains a crystalline phase, and the cross-sectional shape of the crystalline phase grains in the pipe substrate layer includes rectangular shapes.

14. The heat exchanger according to claim 13, characterized in that, The first side length of the rectangle is 0.1–25 mm; And / or, the second side length of the rectangle is 0.1 to 7 mm.

15. The heat exchanger according to claim 14, characterized in that, The ratio of the length of the first side to the length of the second side is 0.7 to 12.

16. The heat exchanger according to claim 1, characterized in that, The zinc content of the pipe is 0.05 to 1 wt%.

17. The heat exchanger according to claim 1, characterized in that, The tubing is a flat tube.

18. The heat exchanger according to claim 17, characterized in that, The width of the flat tube is 6 to 60 mm; And / or, the height of the flat tube is ≤5mm; And / or, the planar wall thickness of the flat tube is 0.15 to 0.45 mm; And / or, the side wall thickness of the flat tube is 0.01 to 1 mm; And / or, the single-tube ultimate pressure resistance value of the flat tube is ≥13MPa.

19. The heat exchanger according to claim 1, characterized in that, The solder layer is made of aluminum alloy; the aluminum alloy used in the solder layer includes the following alloying elements by mass percentage: Cu: 0.01-0.52 wt%; Si: 1-10 wt%; Fe: 0.1~0.8wt%; Mn: 0.1~1.5wt%; Mg: ≤0.5wt%; Cr, Zr, In: Cr+Zr+In≤0.2%; And Fe+Mn≤2wt%.

20. The heat exchanger according to claim 1, characterized in that, The fin substrate layer is made of aluminum or aluminum alloy.

21. The heat exchanger according to claim 1, characterized in that, The leakage duration of the heat exchanger in the seawater acid salt spray test is ≥1500h; And / or, the pipe corrosion depth of the heat exchanger in a 1000-hour seawater acidic salt spray test is ≤120μm; And / or, the ratio of the pipe corrosion depth to the pipe wall thickness in the 1000h seawater acidic salt spray test of the heat exchanger is ≤0.

26.

22. A method for preparing a heat exchanger according to any one of claims 1 to 21, characterized in that, Includes the following steps: The heat exchanger is obtained by brazing the tube and the fins.

23. The preparation method according to claim 22, characterized in that, The temperature for the brazing process is 300–620°C.

24. The preparation method according to claim 22, characterized in that, The brazing process takes 1 to 30 minutes.

25. A temperature regulating device, characterized in that, Includes the heat exchanger as described in any one of claims 1 to 21.

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