WO2023024743A1

WO2023024743A1 - Heat exchanger and processing method therefor

Info

Publication number: WO2023024743A1
Application number: PCT/CN2022/105449
Authority: WO
Inventors: 黄海; 唐建华; 余书睿; 薛明; 黄宁杰
Original assignee: 杭州三花研究院有限公司
Priority date: 2021-08-27
Filing date: 2022-07-13
Publication date: 2023-03-02
Also published as: CN115900422A

Abstract

The present application provides a processing method for a heat exchanger and a heat exchanger. The processing method for a heat exchanger comprises the following steps: providing a heat exchanger, the heat exchanger comprising a manifold, a fin and a plurality of heat exchange pipes fixed together, inner cavities of the heat exchange pipes communicating with an inner cavity of the manifold, and the fin being fixedly connected between two adjacent heat exchange pipes; and performing sandblasting on the heat exchanger, so that a rough surface is formed on at least a part of an outer surface of a metal substrate corresponding to at least one among the manifold, the fin, or the heat exchange pipes. Sandblasting is beneficial for removing attached impurities on the outer surface of the metal substrate and reducing the dangerousness and pollution of the process; meanwhile, the rough surface formed after passing through sandblasting is beneficial for improving the adhesive ability of the metal substrate of the heat exchanger to bind with other coating materials.

Description

Heat exchanger and its treatment method

Cross References to Related Applications

This application claims the priority of the Chinese invention patent application filed on August 27, 2021 with the application number 202110997970.3 and the title of the invention is "Heat Exchanger Treatment Method and Heat Exchanger". The relevant content of the patent application is cited form is incorporated into this article.

technical field

The invention relates to the technical field of heat exchange and material processing, in particular to a heat exchanger processing method and the heat exchanger.

Background technique

The manufacturing process of the heat exchanger in the related art includes fixing the header, heat exchange flat tubes and fins together to form a heat exchanger through a brazing process, and coating various functional coatings on the surface of the heat exchanger. Layers and other steps, but after brazing treatment, a large amount of flux will remain on the outer surface of the metal base material corresponding to the heat exchanger. In addition, the surface of the metal substrate of the heat exchanger will also form an oxide layer after being placed for a long time, and there will be some pollutants such as oil stains on the surface of the metal substrate of the heat exchanger. These attached impurities will subsequently affect the adhesion of the coating.

In some technologies, there is pickling or alkaline cleaning of the above-mentioned heat exchanger, that is, removing the attached impurities on the outer surface of the metal substrate by chemical reaction, and changing the shape of the metal substrate to a certain extent, but the cost of the above method is It is relatively high, and there is a certain operational risk in the cleaning process, and the waste liquid is highly polluting to the environment. Therefore, there is a need for improvement in related technologies.

Contents of the invention

The application provides a heat exchanger treatment method and the heat exchanger. On the basis of effectively removing the impurities attached to the surface of the metal substrate of the heat exchanger and reducing the operational risk and pollution in the process, the metal substrate is improved. Adhesion ability in combination with other coating materials.

In a first aspect, the present application provides a treatment method for a heat exchanger, the treatment method comprising the following steps:

A heat exchanger is provided, the heat exchanger includes a header fixed together, fins and a plurality of heat exchange tubes, the inner cavity of the heat exchange tube communicates with the inner cavity of the header, the At least part of the fins are connected between two adjacent heat exchange tubes;

Sand blasting is performed on the heat exchanger, so that at least part of the outer surface of the metal substrate corresponding to at least one of the header, the fins, and the heat exchange tube forms an uneven rough surface.

In this application, the outer surface of the heat exchanger is treated by sand blasting, which is beneficial to remove the attached impurities remaining on the outer surface of the metal substrate, and reduces the risk and pollution of the process. At the same time, because the surface of the metal substrate has undergone After the sandblasting treatment, an uneven rough surface is formed, and the rough surface is conducive to improving the adhesion ability of the metal substrate of the heat exchanger combined with other coating materials.

In a second aspect, the present application provides a heat exchanger, which includes a header, fins and a plurality of heat exchange tubes fixed together;

A plurality of heat exchange tubes are arranged along the length direction of the header, and the inner cavity of the heat exchange tube communicates with the inner cavity of the header;

At least part of the fins are connected between two adjacent heat exchange tubes;

The outer surface of the metal substrate corresponding to at least one of the header, the fins and the heat exchange tubes includes an uneven rough surface.

In the present application, the outer surface of the metal substrate corresponding to at least one of the headers, fins and heat exchange tubes includes an uneven rough surface, which is conducive to improving the contact between the metal substrate of the heat exchanger and other Adhesion ability of the coating material bond.

Description of drawings

FIG. 1 is a schematic structural view of a heat exchanger provided in an embodiment of the present application;

Fig. 2 is a schematic diagram of the assembly structure of heat exchange tubes and fins in Fig. 1 of the present application;

Fig. 3 is a schematic structural view of the heat exchange tube in Fig. 1 of the present application;

Fig. 4 is the structural representation of the fin in Fig. 1 of the present application;

Fig. 5 is a flow chart of a processing method for a heat exchanger provided in an embodiment of the present application;

Fig. 6 is a flow chart of a treatment method for a heat exchanger provided in another embodiment of the present application;

Figure 7 is a schematic diagram of the effect comparison of the heat exchanger fins in the present application after sandblasting treatment for 1 time, 3 times and 5 times respectively;

Figure 8 is a schematic diagram of the comparison of rough surface effects formed before and after sandblasting of aluminum plates in this application;

Fig. 9 is the surface topography diagram of the samples prepared in Example 1, Example 3 and Example 8 of the present application after 168h salt spray test, wherein, Figure (S1) corresponds to the sample prepared in Example 1, and Fig. (S2) corresponds to the sample made in Example 3, and figure (S3) corresponds to the sample made in Example 8;

Figure 10 is a comparison chart of the salt spray test results of Example 3 and Comparative Examples 1 to 3 of the present application, wherein Figure (P1) is the surface morphology of the sample prepared in Example 3 after a 196h salt spray test. (P2) is the surface topography figure of the sample made in comparative example 1 after the 24h salt spray test, and figure (P3) is the surface topography figure of the sample made in comparative example 2 after the 24h salt spray test, Fig. (P4) is the surface topography figure of the sample prepared in Comparative Example 3 after the 24h salt spray test;

Fig. 11 is the surface topography diagram of the samples prepared in Example 10 and Comparative Example 5 of the present application after a 48h salt spray test, wherein, Figure (F1) corresponds to the sample prepared in Comparative Example 5, and Figure (F2) Corresponding to the sample prepared in Example 10.

Detailed ways

In order to better understand the technical solutions of the present application, the embodiments of the present application will be described in detail below in conjunction with the accompanying drawings.

It should be clear that the described embodiments are only some of the embodiments of the present application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by persons of ordinary skill in the art without creative efforts fall within the protection scope of this application.

Terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of this application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

It should be understood that the term "and/or" used herein is only an association relationship describing associated objects, which means that there may be three relationships, for example, A and/or B, which may mean that A exists alone, and A and B exist simultaneously. B, there are three situations of B alone. In addition, the character "/" in this article generally indicates that the contextual objects are an "or" relationship.

The present application provides a heat exchanger, which in some embodiments is specifically a microchannel heat exchanger.

1, the heat exchanger 100 includes two headers 11, a plurality of heat exchange tubes 12 and a plurality of fins 13, in the heat exchanger, a plurality of heat exchange tubes 12 are fixed to the header 11, The heat exchange tubes 12 are provided with multiple passages for refrigerant circulation, and the multiple passages of the heat exchange tubes 12 are all communicated with the inner cavity of the header 11, and the fins 13 are located between two adjacent heat exchange tubes 12 , the outer surface of the metal substrate corresponding to the header 11, the fins 13 and the heat exchange tube 12 can be a rough surface after the sandblasting process. In FIG. 1, the rough surface of the metal substrate corresponding to the heat exchange tube 12 121 makes a signal. The header 11 is provided with a fluid inlet 101 and a fluid outlet 102 communicating with its inner cavity, so as to facilitate the fluid to enter the heat exchanger.

The heat exchanger 100 of the present application can be a microchannel heat exchanger. Specifically, a plurality of heat exchange tubes 12 are arranged along the length direction of the header 11, and the length direction of the header 11 can refer to the X direction in FIG. 1 .

The heat exchange tube 12 is a longitudinally extending tubular structure. The length direction of the heat exchange tube 12 can refer to the Y direction in FIG. 1 and FIG. 2 , and the width direction of the heat exchange tube 12 can refer to the D direction in FIG. 2 . The width of the heat exchange tube 12 is greater than the thickness of the heat exchange tube 12 , and the thickness direction of the heat exchange tube 12 is substantially coincident with the length direction (X direction) of the header 11 . Moreover, the width direction (D direction) of the heat exchange tube 12 is not in the same direction as the length direction (X direction) of the header 11 . The width direction (D direction) of the heat exchange tube 12 in FIG. 2 is substantially perpendicular to the length direction (X direction) of the header 11 in FIG. 1 .

In some embodiments, the material of the metal substrate corresponding to any one of the headers 11 , the fins 13 and the heat exchange tubes 12 includes at least one of aluminum, copper and stainless steel. For example, the header 11, the fins 13 and the heat exchange tubes 12 are all made of aluminum.

In some embodiments, the roughness Ra of the rough surface of the metal substrate is 0.5 μm˜10 μm, and in some embodiments, the roughness Ra of the rough surface of the metal substrate is 1 μm˜3 μm. Specifically, the roughness of the rough surface coated with the above-mentioned metal substrate can be 1 μm, 1.2 μm, 1.4 μm, 1.6 μm, 1.8 μm, 2.0 μm, 2.2 μm, 2.4 μm, 2.6 μm, 2.8 μm, 3 μm, etc., but It is not limited to the listed values, and other unlisted values within the range of values are also applicable. Controlling the roughness of the metal substrate surface can make it have good durability when combined with other subsequent coating materials. Although the roughness is larger, it is conducive to the adhesion of the subsequent coating, but the roughness is too large, such as exceeding 10μm , the degree of deformation of the metal substrate is relatively large, and the thickness of the metal substrate is relatively high, otherwise the metal substrate is easily damaged.

For metal substrates that have not been sandblasted, due to the different and uneven residual impurities on the surface of the metal substrate, the roughness error at each position is relatively large.

In FIG. 1 , there are two headers 11 , and both ends of the heat exchange tubes 12 in the longitudinal direction (Y direction) communicate with the inner cavities of the two headers 11 . This type of heat exchanger is also commonly referred to as a single-row heat exchanger in the industry. In some other embodiments, the number of headers 11 may be one or more than two. Correspondingly, the number of heat exchange tubes and fins is also set according to actual product needs.

In some embodiments, referring to FIG. 2 , the fins 13 are wave-shaped structures extending along the length direction (Y direction) of the heat exchange tube 12 . The fin 13 includes a plurality of fin units 131 arranged along the length direction (Y direction) of the heat exchange tube 12, and the plurality of fin units 131 are connected in sequence along the length direction (Y direction) of the heat exchange tube 12. The peaks or troughs in the wave structure corresponding to the fins 13 are formed at the positions where two fin units 131 are connected, and the fins 13 are fixed to the heat exchange tubes 12 at the positions where two adjacent fin units 131 are connected. .

As shown in FIG. 3 , the heat exchange tube 12 includes two side surfaces 122 and two end surfaces 123, the two side surfaces 122 are arranged roughly in a plane, and the two side surfaces 122 are arranged in parallel, and the two side surfaces 122 are respectively located at the thickness of the heat exchange tube 12. The opposite sides of the direction (X direction). The two end surfaces 123 are respectively located on opposite sides of the heat exchange tube 12 in the width direction (D direction).

The rough surface includes a first rough surface and a second rough surface, the first rough surface is at least a part of the end surface 123 , and the second rough surface is at least a part of the side surface 122 . The roughness of the first rough surface is greater than or equal to the roughness of the second rough surface. Since the impact strength of the heat exchange tube 12 is greater than the impact strength of the fin 13, the roughness of the outer surface of the metal base material of the fin 13 is smaller than the roughness of the outer surface of the metal base material of the heat exchange tube 12, so that both The strength of the fins 13 and the adhesion to the coating on the surface of the fins 13 reduce the damage to the fins 13 when the outer surface roughness is formed by sandblasting, and improve the adhesion of the coating on the surface of the heat exchange tubes 12 .

The advantage of doing this is that since the heat exchange tube 12 is a flat tubular structure, the arcs of the two end surfaces 123 are relatively large and relatively narrow in size. When the metal base material of the subsequent heat exchange tube 12 is combined with the coating material, At the end face 123 with a large radian, it is more difficult to combine with the coating material. In order to improve the bonding ability of this position and the coating, the roughness of the end face 123 can be set to be larger than the roughness of the side 122. Like this, The relatively uneven surface structure of the metal substrate can be better combined with the coating material, so that the binding force between the end surface 123 and the coating material is stronger, and correspondingly, the binding force of the coating material at this position can be improved. durability.

Further, for the side surface 122 of the heat exchange tube 12 , the side surface 122 is relatively flat. The side surface 122 can be divided into three regions according to the width direction (D direction) of the heat exchange tube 12, that is, the side surface 122 includes two first regions 31 and one second region 32, and the second region 32 is located in the two first regions 31 Between, so that the first region 31 is closer to the end surface 123 than the second region 32 . The roughness of the second rough surface in the first region 31 is greater than or equal to the roughness of the second rough surface in the second region 32 . The advantage of this arrangement is that, in the width direction (D direction) of the heat exchange tube 12, the relatively outer first region 31 contacts the air relatively early in the heat exchange process, so that the air moves along the heat exchange tube. When the flow is in the width direction (D direction) of the heat exchange tube 12, the relatively outer part of the heat exchange tube 12 is more likely to accumulate water vapor, so that this part is more likely to be frosted as the windward side. In order to improve the bonding force between the part and the coating material, the roughness of the second rough surface in the first region 31 can be correspondingly set to be greater than or equal to the roughness of the second rough surface in the second region 32 .

Correspondingly, the principle of setting the roughness of each area of the fin 13 is similar. For the fin 13, referring to FIG. 4 , along the width direction (D direction) of the fin unit 131, the fin unit 131 is divided into three areas, namely The surface of the fin unit 131 includes two third regions 33 and one fourth region 34 . The fourth region 34 is located between the two third regions 33 . That is, in the width direction (direction D) of the fin unit 131 , the third region 33 is further outside than the fourth region 34 . The roughness of the rough surface of the fin 13 in the third region 33 is greater than or equal to the roughness of the rough surface of the fin 13 in the fourth region 34 . In this way, the roughness of the position where the fins are prone to frost is greater, so that the bonding ability between the metal base material and the coating material at this position can be improved. The coating material can be a hydrophilic coating material or a hydrophobic coating material that is easy to drain, and the durability of the coating material is improved, so that the drainage capacity at this position is strong, and it is not easy for frost to affect the heat exchange performance.

As shown in FIG. 5 , the rough surface formed on the surface of the metal substrate of the heat exchanger is prepared in the following manner in some embodiments of the present application.

Step S11 , providing a heat exchanger, which includes a header, fins and heat exchange tubes fixed together. Specifically, the headers, fins, and heat exchange tubes are fixed by welding process, and the heat exchanger after the welding process satisfies the inner cavity of the heat exchange tubes and the inner cavity of the header tubes, and the fins are fixedly connected to the corresponding Between two adjacent heat exchange tubes.

Step S21, performing sandblasting on the heat exchanger. The sand blasted heat exchanger satisfies the requirement that at least part of the outer surface of the metal substrate corresponding to at least one of the header, the fins and the heat exchange tube is roughened.

The welding method between the header, fins and heat exchange tubes can be brazing, that is, these parts are welded as a whole through brazing, and the brazing process is conducive to realizing the sealing between the connection positions of the above-mentioned parts. However, the brazing process will leave flux on the outer surface of the metal base material of the header, fins and heat exchange tubes, and the flux itself is limited by the nature of the material. The flux is an inorganic material with poor adhesion. The combination of coating materials is difficult, and in actual application, the position where flux remains is not easy to cover the coating. In addition, if the metal base material of each part of the heat exchanger is exposed to the air for a long time, the application will also form an oxide layer, which is also unfavorable for combining with some types of coating materials. Therefore, the surface of the heat exchanger needs to be treated before coating to remove residual flux, oxides, oil stains and other pollutants on the surface, and to construct a certain surface rough structure to facilitate coating adhesion.

At present, the surface treatment method of the heat exchanger in the related art is chemical treatment, that is, pickling, alkali washing, and using solvents such as acid and alkali as cleaning agents to chemically react with metal oxides, flux, etc. to remove excess residue on the surface of the metal substrate. attachments. However, the cost required by this method is high, and the process is relatively complicated, causing serious pollution to the environment, and there is a certain risk in the cleaning process. Cleaning with organic solvents will produce a large amount of waste solvents, which are difficult to handle and cause great harm to the human body and the environment. At the same time, the flammable and explosive properties of solvents pose safety hazards. The cleaning process will generate waste water, and the cleaning quality is difficult to guarantee, and only part of the contaminants can be removed. Furthermore, it is difficult to form a regular rough surface on the metal substrate by the above method, which has no additive effect on the subsequent coating on the heat exchanger.

In the embodiment provided in this application, the method of sandblasting the heat exchanger is used to remove the attachments on the surface of the metal substrate, so that the metal substrate can be exposed, and the surface of the metal substrate is treated by sandblasting This physical treatment method makes the surface of the metal substrate form a rough surface, and the formation of the above rough surface is obtained based on physical deformation after sandblasting. Sandblasting uses compressed air as the medium, and the abrasive is mixed in the compressed air and sprayed onto the surface of the heat exchanger, so that the surface of the metal substrate can obtain a certain degree of roughness and cleanliness.

The advantages of the above-mentioned sand blasting treatment include, firstly, it can remove a large amount of flux, oxide layer, oil stains, etc. remaining on the surface of the metal substrate, and obtain a relatively clean surface of the metal substrate. In the second aspect, the sandblasting and grinding effect of abrasives is conducive to the formation of a better microscopic rough surface structure on the surface of the metal substrate, thereby increasing the subsequent bonding force with other coating materials, which is beneficial to the leveling and decoration of the coating. In the third aspect, the cutting and impact of sand blasting strengthen the mechanical properties of the surface of the metal base material and improve the fatigue resistance of the metal base material. In the fourth aspect, sand blasting can remove irregular structures such as burrs on the surface of the metal substrate, and create small rounded corners on the surface of the metal substrate, especially at the junction where various parts are connected, so that the surface of the metal substrate It is more smooth and beautiful, which is conducive to subsequent processing. After sandblasting, the surface structure of the metal substrate changes, and the metal grains become more refined and dense. After sandblasting, more hydroxyl groups are formed on the surface of the metal substrate. In the subsequent process of connecting with the coating, such as some functional film layers, the hydroxyl groups of the functional film layer and the hydroxyl groups of the metal substrate are dehydrated and condensed. Therefore, the functional film layer and the metal substrate can be connected by covalent bonds, and the covalent bond connection mode is relatively stable, which is beneficial to improving the durability of the connection with the functional film layer.

In addition, the sand blasting process has the characteristics of high efficiency, low cost, and is suitable for cleaning large surface areas of metal substrates. Furthermore, the abrasives used in the sand blasting process can be recycled and reused, thereby further reducing costs.

In this application, the treatment steps of first welding and then sandblasting of the heat exchanger can effectively remove impurities attached to the surface of the heat exchanger during the welding process, and form an uneven rough surface on the surface of the metal base material. And if sandblasting is performed on the surface of each part of the heat exchanger first, and then assembled and welded, impurities during the welding process will still adhere to the rough surface, thereby affecting the coating of subsequent coating materials.

In some embodiments of the present application, step S21, that is, the step of sandblasting the heat exchanger includes: mixing abrasives in compressed air, and spraying them on the outer surface of the heat exchanger through a spray gun. Further, the abrasive can be grit made of corundum, such as brown corundum, white corundum, black corundum, garnet and the like. The abrasive can also be silicon carbide gravel, such as black silicon carbide, green silicon carbide and the like. Of course, when choosing abrasives, you can also choose other types of gravel, such as glass beads, steel shot, steel sand, ceramic sand, resin sand, walnut sand, etc.

In some embodiments, the particle size of the abrasive is between 30 mesh and 280 mesh. Specifically, the particle size of the abrasive can be 30 mesh, 50 mesh, 80 mesh, 120 mesh, 150 mesh, 180 mesh, 200 mesh, 220 mesh, 250 mesh, 280 mesh and so on. The particle size selection of the abrasive will affect the construction of the rough surface of the metal substrate. When the particle size of the abrasive is relatively large, the rough surface of the metal substrate will be finer. When the particle size is too large, the rough surface will be finer. Roughness will be difficult to guarantee. When the particle size is too small, it will be relatively slow to construct a rough surface with a certain roughness, and the roughness effect will be poor. In some embodiments, the particle size of the abrasive may range from 100 mesh to 200 mesh. In this way, the particle size of the abrasive is neither too large nor too small, and correspondingly, it is easier to obtain an ideal rough surface structure.

In some embodiments, the distance between the spray gun and the corresponding spray location on the outer surface of the heat exchanger is between 20 mm and 100 mm. Specifically, the distance between the nozzle of the spray gun and the corresponding injection position on the outer surface of the heat exchanger is simply recorded as the sandblasting distance. If the sandblasting distance is too short, it is easy to have pits on the surface of the metal substrate, and the overall rough surface morphology Poor, the sandblasting distance is too far, and the impact force of the abrasive is poor, which makes the surface morphology of the metal substrate poor. In this application, the sandblasting distance can be selected from 20mm, 30mm, 40mm, 50mm, 60mm, 70mm, 80mm, 90mm, 100mm and so on. In some embodiments, the blasting distance may be between 50 mm and 100 mm.

In some embodiments, the spray angle α of the spray gun satisfies 0<α≦90°. The spray angle of the spray gun refers to the angle between the incident direction of the abrasive and the plane where the spray position of the heat exchanger is located. Specifically, the spray angle α of the spray gun is 15°, 30°, 45°, 60°, 75°, 90° and so on. If the spray angle α of the spray gun is too small, the interference angle between the metal substrate and the abrasive is small, and it is difficult to form a rough surface. The spray angle α of the spray gun can be an acute angle less than or equal to 90°. In some embodiments of the present application, the spray angle α of the spray gun is 45°.

In some embodiments, the pressure of the compressed air is 0.45MPa˜0.65MPa, specifically, the pressure of the compressed air is 0.45MPa, 0.5MPa, 0.55MPa, 0.6MPa, 0.65MPa. Since the manifolds, fins and heat exchange tubes of the various parts of the heat exchanger are mostly made of aluminum in the industry, correspondingly, the aluminum material is relatively soft, so the pressure of the compressed air should not be too high, otherwise it is easy to cause damage to the parts . Of course, the pressure of the compressed air should not be too low, otherwise it will be difficult to form a rough surface. In some embodiments of the present application, the pressure of the compressed air is 0.45MPa.

In the field of heat exchangers, the material of the fins arranged between adjacent heat exchange tubes is relatively thin. In order to prevent the fins from being damaged by abrasives during the sandblasting process, it is necessary to control the number of sandblasting times on the fins. In the embodiment of the present application, the number of times of blasting the fins is less than or equal to 3. Refer to the schematic diagram of the comparison of sandblasting times in the fin position in Fig. 7. In Fig. 7, the (c) pattern shows the deformation of the fins after one pass of sandblasting, and the pattern (d) shows the deformation of the fins after three passes of sandblasting, (e ) pattern shows the deformation of the fins after sandblasting 5 times. It can be seen from Figure 7 that after the first pass of sandblasting at the fin position, the deformation of the fins is relatively light. increases, the fin deformation tends to be more serious. In the 5th pass, a small area of fin damage has occurred, and the fins have been pierced by gravel. In at least some embodiments of the present application, the number of sandblasting passes on the fins may be controlled to not exceed 3 times. Specifically, the number of times of blasting the fins may be one time. The number of sandblasting times for the header and heat exchange tubes can be greater than or equal to 1 time. If the tube wall of the header is thicker, correspondingly, the sandblasting of the header can be performed 1 to 2 times more.

Referring to Fig. 6, before the step S21 of the present application, that is, before the step of sandblasting the heat exchanger, it also includes:

Step S20, blocking the fluid inlet and fluid outlet connected to the lumen of the collecting pipe. Typically, a header will be provided with a fluid inlet and a fluid outlet. The fluid inlet 101 and the fluid outlet 102 provided by the collector 11 in Fig. 1, the fluid inlet 101 and the fluid outlet 102 are connected with the lumen of the collector 11, and during the specific operation of step S20, the sealing of the rubber plug material can be selected The component seals the fluid inlet and fluid outlet of the header, which has the advantage of preventing abrasives, that is, grit, from entering the lumen of each component of the heat exchange tube, thereby avoiding affecting the flow of fluid. The plugged heat exchanger can be put into the sandblasting machine as a whole for sandblasting operation.

After step S21, that is, the step of sandblasting the heat exchanger, it also includes:

Step S22, performing ultrasonic cleaning treatment on the heat exchanger after the sandblasting treatment.

Specifically, in step S22, ultrasonic cleaning is performed on the heat exchanger after sandblasting, including:

At least one of deionized water, ethanol and absolute ethanol is used to ultrasonically clean the heat exchanger after sandblasting, the duration of ultrasonic cleaning is 5min-10min, and the ultrasonic frequency of ultrasonic cleaning is 80Hz-100Hz. After the heat exchanger after sandblasting is cleaned by ultrasonic cleaning, the remaining grit on the surface of the heat exchanger can be removed to avoid affecting the coating of the subsequent film layer.

Step S23 , drying the heat exchanger after the ultrasonic cleaning treatment.

Specifically, step S23, drying the heat exchanger after the ultrasonic cleaning treatment, includes:

The ultrasonically cleaned heat exchanger is dried or dried naturally. If the drying method is used for drying, the drying temperature can be selected at a temperature above 40°C. The dried heat exchanger is reserved for future use.

In some embodiments, the above-mentioned heat exchanger after sandblasting can be ultrasonically cleaned with deionized water, acetone, and ethanol in sequence. , the ultrasonic cleaning time can be 5min, 6min, 7min, 8min, 9min, 10min, etc., which is not limited here, but is not limited to the listed values. Other unlisted values within this value range are also applicable. Put it into the oven after ultrasonic Dry in medium.

Further, in order to prevent the heat exchanger after the drying treatment from being exposed to the air for a long time, the bare and clean metal substrate is prone to form an oxide layer or be contaminated with other pollutants on the surface. In some embodiments of the present application, it may further include:

Step S30, setting a functional film layer on the surface of the rough surface formed by sandblasting.

In some embodiments, coatings can be provided on the metal substrate surfaces corresponding to the headers, heat exchange tubes and fins according to specific needs, for example, functional coatings can be provided on at least the surfaces of the metal substrates corresponding to the heat exchange tubes and fins film layer for better durability of the effect.

Specifically, in step S30 , that is, the step of providing a functional film layer on the surface of the sandblasted rough surface can be realized in various ways according to the type of the functional film layer.

In the first optional embodiment, step S30 includes coating a hydrophilic coating or a hydrophobic coating comprising a silane-based sol on at least a partial area of the rough surface, and forming a film comprising a silane-based sol on the rough surface after curing layer.

The film layer comprising silane sol includes silane sol material containing hydrophobic groups or hydrophilic groups. Taking hydrophobic groups as an example, the hydrophobic groups contained in the functional film layer are C10-C20 hydrocarbon groups, hydrocarbon groups containing aryl groups, esters, ethers, amines, amides and other groups, or hydrocarbon groups containing double bonds.

In the manufacturing method, take the hydrophilic film layer prepared by the hydrophilic coating as an example. Specifically, the heat exchanger after sandblasting can be soaked in the hydrophilic coating including silane sol by dip coating. Among them, the number of times of dipping is 1 time, and the duration of dipping is controlled at more than 2 minutes. After taking it out, you can use an air gun to blow off the excess liquid, and then fix it at 200 ° C for more than 10 minutes to obtain a hydrophilic coating. layer heat exchanger.

In a second optional implementation manner, step S30 includes coating a rare earth conversion coating on at least a part of the rough surface, and after curing, a rare earth conversion coating including a rare earth element-containing compound is formed on the rough surface.

At least part of the surface of the rare earth conversion coating is coated with a hydrophilic coating or a hydrophobic coating comprising silane sol, and after curing, a film layer comprising silane sol is correspondingly formed on the surface of the rare earth conversion coating.

Specifically, the heat exchanger after sandblasting can be soaked in the conversion solution containing rare earth element cerium by dip coating. Dry it with an air gun to obtain a heat exchanger with a cerium conversion film. After that, soak the above parts in the hydrophobic coating including silane-based sol by dip coating. The number of dip coatings is 1 time, and the dip coating time is controlled at more than 2 minutes. After taking it out, you can blow off the excess material liquid with an air gun , and then fixed at a temperature of 120°C for more than 20 minutes, a heat exchanger with a double-layer coating, that is, a top coating of a hydrophobic coating and a bottom coating of a rare earth conversion coating can be obtained. The heat exchanger has better Hydrophobic anti-corrosion function.

In a third optional implementation manner, step S30 includes coating a coating including chromate on at least a partial area of the rough surface, and forming a chromate passivation film layer on the rough surface after curing.

Specifically, the heat exchanger after sandblasting can be soaked in the passivation liquid paint including chromate by dip coating, the reaction temperature is controlled at 40°C, the dip coating time is controlled at more than 2 minutes, and the Finally, the excess material liquid can be blown off with an air gun, and then fixed at a temperature of 40°C for more than 10 minutes, a heat exchanger with a chromium salt passivation film can be obtained, and the heat exchanger has good anti-corrosion performance .

In other embodiments of the present application, the functional film layer may also be other types of coatings, such as dustproof coatings, antibacterial coatings, and the like. The thickness of the functional film layer is 10 μm to 14 μm, specifically, it can be 10 μm, 10.3 μm, 10.6 μm, 12 μm, 14 μm, etc., but it is not limited to the listed values, and other unlisted values within this range are also applicable . If the coating is too thick, resources will be wasted and the heat exchange efficiency of the heat exchanger will be affected. If the coating is too thin, the ideal coating effect will not be achieved.

The multiple embodiments provided by the present application are described below, and the effects are compared.

In Examples 1 to 8 described below, in order to facilitate performance testing, an aluminum plate is used as a test sample, that is, an aluminum plate is used for sandblasting, and a rare earth conversion coating and hydrophobic coating are coated on the aluminum plate after sandblasting. Coatings are tested. The aluminum plates used in the test samples are basically the same as those of conventional aluminum heat exchangers in the field.

Example 1

(1) Put the test sample into the sandblasting machine for sandblasting, set the abrasive as white corundum with a particle size of 120 mesh, the distance between the spray gun and the position to be sprayed on the heat exchanger is 50mm, and the spray angle of the spray gun is 45° , the pressure of compressed air in the spray gun is 0.45MPa, and the number of sandblasting is 1 time.

(2) Take out the sample after sandblasting, spray the surface of the sample with absolute ethanol, and then dry it at 40°C for later use.

(3) On the basis of the sample in step (2), coat the rare earth conversion solution containing cerium on the surface of the sample by dip coating, and control the dip coating time at about 10 minutes at a reaction temperature of 50°C , take out the air gun and blow dry to obtain a sample with a cerium conversion coating.

(4) On the basis of the sample in step (5), the hydrophobic coating including silane sol is coated on the surface of the cerium conversion membrane by dip coating, the number of dip coating is 1 time, and the dip coating time is controlled at 2min Left and right, after taking it out, the air gun blows off the excess liquid, and then fixes it at a temperature of 120°C for more than 20 minutes to obtain a sample with a rare earth conversion coating and a hydrophobic coating.

Example 2

The difference from Example 1 is that in step (1), the spray angle of the spray gun is adjusted to 90°.

Example 3

The difference from Example 1 is that in step (1), the distance between the spray gun and the position where the sample is to be sprayed is adjusted to 100 mm.

Example 4

The difference from Example 1 is that in step (1), the distance between the spray gun and the sample to be sprayed is adjusted to 100 mm, and the spray angle of the spray gun is adjusted to 90°.

Example 5

The difference from Example 1 is that in step (1), the abrasive is adjusted to white corundum with a particle size of 150 mesh.

Example 6

The difference from Example 1 is that in step (1), the abrasive is adjusted to white corundum with a particle size of 150 mesh, and the distance between the spray gun and the position to be sprayed on the sample is adjusted to 100 mm.

Example 7

The difference from Example 1 is that in step (1), the abrasive is adjusted to white corundum with a particle size of 200 mesh.

Example 8

The difference from Example 1 is that in step (1), the abrasive is adjusted to white corundum with a particle size of 200 mesh, and the distance between the spray gun and the position to be sprayed on the sample is adjusted to 100 mm.

In Example 9 attached below, in order to facilitate the performance test, an aluminum plate is used as a test sample, that is, an aluminum plate is used for sand blasting, and a hydrophilic coating is coated on the sand blasted aluminum plate for testing. The aluminum plates used in the test samples are basically the same as those of conventional aluminum heat exchangers in the field.

Example 9

The difference from Example 1 is that the coating material of Example 9 is specifically a sol-gel type hydrophilic coating comprising a silane system, specifically:

(1) Provide test samples after sandblasting.

(2) The hydrophilic sol coating of the silane system is coated on the surface of the test sample in step (1) by dip coating, the number of dip coating is 1 time, and the dip coating time is controlled at 2min. Blow off the excess material liquid, and then fix at a temperature of 200°C for more than 10 minutes to obtain a sample with a hydrophilic coating.

In Example 10 attached below, for the convenience of performance testing, an aluminum plate is used as a test sample, that is, an aluminum plate is used for sandblasting, and a passivation agent including chromate is coated on the aluminum plate after the sandblasting. Liquid paint was tested. The aluminum plates used in the test samples are basically the same as those of conventional aluminum heat exchangers in the field.

Example 10

The difference from Example 1 is that the coating material of Example 10 is specifically a passivation film layer comprising chromate, specifically:

(1) Provide test samples after sandblasting.

(2) Coating the passivation solution coating comprising chromate on the surface of the test sample in step (1) by dip coating, the reaction temperature is controlled at 40°C, and the dip coating time is controlled at 2min. After taking it out, use Air gun blows off the excess material liquid, and then fixes it at a temperature of 40°C for more than 10 minutes to obtain a sample with a chromium salt passivation film layer.

Comparative example 1

Compared with Example 1, the test sample of Comparative Example 1 was not subjected to the step of blasting treatment. Specifically, Comparative Example 1 includes the following steps:

(1) Coat the rare earth conversion solution containing cerium on the surface of the test sample by dip coating. At a reaction temperature of 50°C, the dip coating time is controlled at about 10 minutes, and the air gun is taken out to dry to obtain Samples of conversion coatings.

(2) On the basis of the sample in step (1), the hydrophobic coating including silane sol is coated on the surface of the cerium conversion membrane by dip coating, the number of dip coating is 1 time, and the dip coating time is controlled at 2min Left and right, after taking it out, the air gun blows off the excess liquid, and then fixes it at a temperature of 120°C for more than 20 minutes to obtain a sample with a rare earth conversion coating and a hydrophobic coating.

Comparative example 2

Compared with Example 1, the test sample of Comparative Example 2 does not carry out the step of sandblasting, but the test sample of Comparative Example 2 has been pickled before coating, specifically:

(1) Immerse the test sample in a 5% hydrochloric acid solution, ultrasonically etch it at room temperature for 10 minutes, take it out, clean it with deionized water and dry it for later use.

(2) On the basis of the sample in step (1), the rare earth conversion solution containing cerium is coated on the surface of the test sample by dip coating, and the duration of dip coating is controlled at 10 minutes at a reaction temperature of 50°C Left and right, take out the air gun and blow dry to obtain a sample with a cerium conversion coating.

(3) On the basis of the sample in step (2), the hydrophobic coating comprising silane sol is coated on the surface of the cerium conversion membrane by dip coating, the number of dip coating is 1 time, and the dip coating time is controlled at 2min Left and right, after taking it out, the air gun blows off the excess liquid, and then fixes it at a temperature of 120°C for more than 20 minutes to obtain a sample with a rare earth conversion coating and a hydrophobic coating.

Comparative example 3

Compared with embodiment 1, the test sample of comparative example 3 does not carry out the step of blasting treatment, but the test sample of comparative example 3 is before coating coating, and test sample has carried out alkali cleaning, specifically:

(1) Immerse the test sample in a 1mol/L NaOH solution, ultrasonically etch it at room temperature for 10 min, take it out, clean it with deionized water and dry it for later use.

Comparative example 4

Compared with Example 9, the test piece of Comparative Example 4 was not subjected to the step of blasting treatment. Other steps are similar, and the present application will not repeat them again.

Comparative example 5

Compared with Example 10, the test piece of Comparative Example 5 was not subjected to the step of blasting treatment. Other steps are similar, and the present application will not repeat them again.

Performance Testing

1. Morphological description before and after sandblasting

Please refer to Figure 8 for the comparison of the rough surface of the aluminum plate before and after sandblasting. In Figure 8 (a) is a schematic diagram of the surface of the metal substrate corresponding to the unsandblasted aluminum plate, and (b) is the corresponding surface of the aluminum plate after sandblasting. Schematic of the metal substrate surface. It can be seen from (a) and (b) that the surface of the metal substrate of the unsandblasted aluminum plate is relatively smooth. After sandblasting, the surface of the metal substrate of the aluminum plate presents an irregular rough surface, and the rough surface presents a deformed wrinkled appearance as a whole. The rough surface has outwardly protruding ridges and inwardly depressed pits The structure also has a barb-shaped structure in some positions, and the position of the barb-shaped structure can refer to the position of the dotted line box in (b). In the subsequent process of combining the rough surface with other coating materials, other coating materials can be filled in the pit structure and fastened by the barb-shaped structure, which increases the bonding between the metal substrate and the coating material The topographical structure plays a role in improving the durability of the coating to a certain extent.

On the whole, the uneven rough surface of the metal substrate after sandblasting is relatively uniform, and the uneven positions in the entire appearance are relatively evenly distributed, while the metal substrate without sandblasting treatment, especially the residual flux The surface of the metal substrate also shows a certain rough structure, but the rough structure is irregular. The position with flux protrudes, and the position without flux is concave, which is far from the rough surface formed by sandblasting. big. Further, for the metal substrate after sandblasting, the metal substrate supporting and adjacent to its rough surface is deformed due to external force during the sandblasting process, and the arrangement of its metal grains is relative to that of the metal on the side away from the rough surface. The substrate is tighter and more uniform. If the rough surface is formed by other methods, the arrangement of metal grains is more scattered and irregular as a whole.

2. Hydrophobic corrosion resistance test

This part of the test is illustrated by taking Examples 1-8 and Comparative Examples 1-3 as examples. Specifically, the samples prepared in Examples 1-8 and Comparative Examples 1-3 are subjected to salt spray tests respectively. Among them, the salt spray test refers to the test standard ASTM G85, and the acid salt spray test is carried out. Each sample is put into the salt spray box, and it is taken out at regular intervals to observe the surface corrosion points. After the acid salt spray test, each sample was taken out to observe its surface corrosion.

Each embodiment of table 1 and comparative example performance test result

From the data in Table 1, it can be seen that the salt spray corrosion spots of the samples corresponding to Examples 1 and 3 appeared relatively late, after 168 hours. In addition, the S1, S2, and S3 patterns in Figure 9 are respectively the original Example 1, Example 3 and Example 8 provided by the application are all 168h salt spray test results. It can be seen from the schematic diagram in 9 that after 168 hours, the number of corrosion spots in the sample corresponding to Example 3 is the least. °. The surface morphology of most of the examples of samples in this application remains relatively good after the salt spray test is over, and most of the samples have slight corrosion spots on their surfaces after 140 hours of salt spray test, indicating that after sandblasting The treated sample, combined with rare earth conversion coating and hydrophobic coating, has excellent corrosion resistance, which can guarantee the heat transfer performance of the heat exchanger product to a certain extent, and can also prolong the service life of the heat exchanger.

Referring to the P1 pattern in Figure 10, it is the salt spray test result diagram of the sample of Example 3 provided by the application after 196h, and P2, P3, and P4 are the comparison examples 1 to 3 provided by the application after 24h Salt spray test results. It can be clearly seen from Figure 10 that corrosion spots appeared in less than 24 hours after the acid salt spray test of Comparative Examples 1 to 3, and regardless of whether they have been subjected to chemical etching processes such as pickling or alkali cleaning, no matter whether they have undergone chemical etching processes such as pickling or alkali cleaning, they will not appear in the test before the test. When setting up the steps of the blasting process, pitting appeared very quickly in a short period of time. However, the sample corresponding to Example 3 of the present application has fewer corrosion spots, shallower corrosion pits and lighter overall corrosion after 196 hours of salt spray testing. This also shows to a certain extent that the samples after blasting treatment have better durability to the coating and stronger corrosion resistance than samples without blasting treatment.

It should be noted that if the heat exchanger product is used to carry out the corrosion resistance test, it can be carried out in the following way. Fill the inner cavity of the heat exchanger with nitrogen to a pressure of 1MPa, and then seal the inlet and outlet of the heat exchanger, leaving A nipple connects to the barometer. Then put the heat exchanger in the salt spray box for salt spray test, and observe the change of the pressure value of the barometer. When the pressure drops, it indicates that a certain part of the heat exchanger is corroded and perforated, and at this time it is recorded as the failure of the heat exchanger. In practice, the corrosion resistance performance can be judged by comparing the time it takes for the heat exchanger to drop to a certain pressure.

3. Hydrophilic durability test

This part of the test takes Example 9 and Comparative Example 4 as an example to carry out the running water test. Specifically, the samples of Example 9 and Comparative Example 4 are immersed in running water, taken out and dried at regular intervals, and the surface contact angle of the test sample is tested. and coating status. The test results are shown in Table 2 respectively:

Table 2

It can be seen from the data in Table 2 that the contact angle of the surface of the sample of Example 9 still shows good hydrophilicity after 336 hours of running water test. However, for the sample of Comparative Example 4, after 240 hours of running water test, the coating fell off in a large area, and it was difficult to ensure hydrophilicity. It shows that the sand blasted sample provided by the present application has better durability to the hydrophilic coating than the non-sand blasted sample.

4. Salt spray comparison test of chromate passivation coating morphology

This part of the test is illustrated with Example 10 and Comparative Example 5 as an example. Specifically, the samples prepared in Example 10 and Comparative Example 5 are carried out to the salt spray test respectively. Among them, the salt spray test refers to the test standard ASTM G85, and the acid salt spray test is carried out. Each sample is put into the salt spray box, and it is taken out at regular intervals to observe the surface corrosion points. Combined with the comparison of the two appearances shown in Figure 11, in Figure 11, the F1 pattern is the salt spray test result of the sample of Comparative Example 5 provided by the application after 48h, and the F2 pattern is the one provided by the application. The sample of embodiment 10 is through 48h salt spray test result picture. It can be clearly seen from Figure 11 that after 48 hours of salt spray test, the comparative example 5 on the left, that is, the sample that has not been sandblasted, has obvious corrosion spots on the surface, a large number, and deep corrosion pits, which can Corrosion marks are more obvious. Example 10 on the right is the sample that has been sandblasted, and the number of corrosion spots on the surface is relatively small, and the corrosion pits are relatively shallow, and the corrosion situation is relatively good, indicating that the sample after sandblasting provided by the application is relatively The durability of the chromate passivation film layer is more excellent than that of the unblasted sample.

The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. For those skilled in the art, there may be various modifications and changes in the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of this application shall be included within the protection scope of this application.

Although the present application is disclosed as above with preferred embodiments, it is not used to limit the claims. Any person skilled in the art can make some possible changes and modifications without departing from the concept of the present application. Therefore, the present application The scope of protection shall be based on the scope defined by the claims of the present application.

Claims

A heat exchanger includes a header, fins and heat exchange tubes; the inner cavity of the heat exchange tube communicates with the inner cavity of the header; at least part of the fins are connected to two adjacent between heat exchange tubes;

At least one of the header, the fins, and the heat exchange tubes has a groove, and the groove extends from at least one of the header, the fins, and the heat exchange tubes. The outer surface of the corresponding metal substrate is formed by inward depression, and the groove makes the outer surface of the metal substrate of at least one of the header, the fin and the heat exchange tube rough;

At least one of the header, the fins, and the heat exchange tubes has a coating, at least part of which is located in the groove, the coating comprising a rare earth conversion coating, a hydrophilic At least one of a coating, a hydrophobic coating and a chromium salt passivation film layer, wherein the rare earth conversion coating includes a rare earth element-containing compound.
The heat exchanger according to claim 1, wherein the roughness of the rough surface is Ra, which satisfies 0.5 μm≤Ra≤10 μm.
The heat exchanger according to claim 1, wherein the heat exchange tube includes two side surfaces and two end surfaces, the two side surfaces are respectively located on opposite sides of the heat exchange tube in the thickness direction, and the two side surfaces The two end surfaces are respectively located on opposite sides of the heat exchange tube in the width direction, and the roughness of the rough surface at the end surfaces is greater than or equal to the roughness of the rough surface at the side surfaces.
The heat exchanger according to claim 1, wherein the side surface of the heat exchange tube is divided into three areas along the width direction of the heat exchange tube, and the three areas include two first areas and two In the second region between the first regions, the roughness of the rough surface in the first region is greater than or equal to the roughness of the rough surface in the second region.
The heat exchanger according to claim 1, wherein the fins include a plurality of fin units arranged along the length direction of the heat exchange tube, and the fin units along the width direction of the heat exchange tube The surface is divided into three areas, the three areas include two third areas and a fourth area between the two third areas, the roughness of the rough surface in the third area is greater than or equal to the The roughness of the rough surface in the fourth region.
The heat exchanger according to claim 1, wherein: the coating includes a rare earth conversion coating, and the coating also includes a hydrophilic coating or a hydrophobic coating, and the rare earth conversion coating is coated on the set The outer surface of the metal substrate corresponding to at least one of the flow tube, the fin and the heat exchange tube, at least part of the rare earth conversion coating is located in the groove, the hydrophilic coating or the The hydrophobic coating is located on a side of the rare earth conversion coating away from the outer surface of the metal substrate corresponding to at least one of the headers, the fins and the heat exchange tubes.
A treatment method for a heat exchanger, wherein the treatment method comprises the following steps:

A heat exchanger is provided, the heat exchanger includes a header, fins and heat exchange tubes, the inner cavity of the heat exchange tube communicates with the inner cavity of the header, and at least part of the fins are connected Between two adjacent heat exchange tubes;

Sandblasting the heat exchanger such that at least one of the headers, the fins, and the heat exchange tubes has grooves extending from the headers, the The outer surface of the metal substrate corresponding to at least one of the fins and the heat exchange tubes is formed by inward depression, and the groove makes at least one of the header, the fins, and the heat exchange tubes The outer surface of the metallic substrate is rough;

Covering the rough surface with a coating so that at least part of the coating is located in the groove, the coating includes a rare earth conversion coating, a hydrophilic coating, a hydrophobic coating and a chromium salt passivation film layer At least one of, wherein the rare earth conversion coating includes a rare earth element-containing compound.
The treatment method according to claim 7, wherein the step of sandblasting the heat exchanger comprises:

Abrasives are mixed in compressed air and sprayed on the outer surface of the heat exchanger through a spray gun.
The treatment method according to claim 8, wherein the step of sandblasting the heat exchanger includes at least one of the following technical features a to d:

A. described abrasive is the gravel of corundum material;

b. The particle size of the abrasive is between 30 mesh and 280 mesh;

c. The pressure of the compressed air is 0.45MPa～0.65MPa;

d. The number of sandblasting passes on the fins is less than or equal to 3.
The processing method according to claim 7, wherein, before the step of sandblasting the heat exchanger, it further comprises:

A fluid inlet and a fluid outlet communicating with the lumen of the header are blocked.
The treatment method according to claim 7, wherein, after the step of sandblasting the heat exchanger, it further comprises:

Ultrasonic cleaning of the heat exchanger after sandblasting;

Dry the heat exchanger after ultrasonic cleaning.
The processing method according to claim 11, wherein the step of ultrasonically cleaning the heat exchanger after sandblasting comprises:

At least one of deionized water, ethanol or absolute ethanol is used to ultrasonically clean the heat exchanger after sandblasting, the duration of the ultrasonic cleaning is 5min to 10min, and the ultrasonic frequency of the ultrasonic cleaning is 80Hz to 100Hz.
The processing method according to claim 7, wherein the step of covering the rough surface with a coating comprises:

Coating a hydrophilic coating or a hydrophobic coating comprising a silane-based sol on at least part of the rough surface, after curing, forming a film layer comprising a silane-based sol on the rough surface;

or,

At least part of the rough surface is coated with a paint comprising chromate, and after curing, a chromate passivation film layer is formed on the rough surface.
The treatment method according to claim 7, wherein the step of applying a coating on the rough surface comprises: coating a rare earth conversion paint on at least a part of the rough surface, and after curing, a coating is formed on the rough surface Rare earth conversion coatings including rare earth element-containing compounds.
The treatment method according to claim 14, wherein the step of coating the rough surface comprises: coating at least part of the surface of the rare earth conversion coating with a hydrophilic coating or a hydrophobic coating comprising a silane-based sol After curing, a film layer including silane-based sol is correspondingly formed on the surface of the rare earth conversion coating.
A heat exchanger comprising:

A metal substrate, the metal substrate has a groove, the groove is formed by inward depression from the outer surface of the metal substrate, and the outer surface of the metal substrate is a rough surface;

A coating, at least part of which is filled in the groove; wherein, the roughness of the rough surface is Ra, which satisfies 0.5 μm≤Ra≤10 μm.
The heat exchanger according to claim 16, wherein the coating comprises at least one of a rare earth conversion coating, a hydrophilic coating, a hydrophobic coating and a chromium salt passivation film layer.
The heat exchanger according to claim 16, wherein the heat exchanger comprises a header and a plurality of heat exchange tubes, the heat exchange tube and the header are fixed, and the heat exchange tube has a plurality of channels , the collecting pipe has an inner cavity, and the plurality of channels are all communicated with the inner cavity;

The heat exchange tube includes the metal base material, and the outer surface of the metal base material of the heat exchange tube is provided with the groove.
The heat exchanger according to claim 18, wherein the heat exchanger comprises fins, the fins are connected between two adjacent heat exchange tubes, the fins comprise the metal substrate, The outer surface of the metal substrate of the fin is provided with the groove.
The heat exchanger according to claim 19, the roughness of the outer surface of the metal base material of the fin is smaller than the roughness of the outer surface of the metal base material of the heat exchange tube.