Fin, manufacturing method thereof and heat exchanger

Abstract

The invention discloses a fin, a preparation method thereof and a heat exchanger, and relates to the technical field of heat exchange. The fin comprises a fin base body and a hydrophobic coating, wherein the surface of the fin base body is coated with the hydrophobic coating; the fin base body comprises a heat transfer section and a drainage section which are arranged in the first direction of the fin base body, and the drainage section is arranged close to the windward side of the fin base body. The heat transfer section is provided with a pipe hole for a heat exchange pipe to penetrate through, and the drainage section is provided with a drainage groove. The designed fins can improve the heat exchange efficiency of the heat exchanger and reduce frosting on one hand, and can prolong the service life of the heat exchanger and maintain the heat exchange efficiency of the heat exchanger at a high level for a long time on the other hand.

Description

Technical Field

[0001] The present invention relates to the field of heat exchange technology, and in particular to a fin and a preparation method thereof, and a heat exchanger. Background Art

[0002] Microchannel heat exchangers are widely used in heat exchange equipment in low-temperature, high-humidity environments, such as air conditioners and heat pumps. Under these conditions, the aluminum foil fins of microchannel heat exchangers are prone to frost, resulting in reduced heat exchange efficiency and increased energy consumption. Heat exchanger fins in related technologies have low drainage efficiency, which easily leads to residual moisture and frost. Alternatively, the fin coating has poor thermal conductivity, which reduces heat exchange efficiency. Alternatively, the fin coating lacks mechanical strength or resistance to cold and heat shock, resulting in defects on the coating surface, which also affects heat exchange. Therefore, there is an urgent need for a fin structure solution that can achieve rapid defrosting and efficient heat exchange to improve heat exchanger performance. Summary of the Invention

[0003] The main purpose of the present invention is to develop a fin based on a drainage groove with a specific curved shape and a hydrophobic thermal conductive coating, so that the rapid drainage of the drainage groove and the efficient thermal conductivity of the coating can work together to further improve the defrosting rate and heat exchange efficiency.

[0004] To achieve the above-mentioned objectives, the present invention proposes a fin, which includes a fin base, and the fin base includes a heat transfer section and a drainage section arranged along a first direction of the fin base, and the drainage section is arranged close to the windward side of the fin base; the heat transfer section is provided with a tube hole for passing a heat exchange tube, and the drainage section is provided with a drainage groove; the drainage groove extends in a fastest curve from one side of the tube hole to the windward side.

[0005] In one embodiment, the drainage section is provided with a plurality of drainage grooves at intervals along a second direction of the fin base, and the second direction intersects with the first direction.

[0006] In one embodiment, the drainage groove extends from one side of the tube hole to the windward side, and the height of the drainage groove in the second direction of the fin base gradually decreases.

[0007] In one embodiment, the drainage groove extends in an arc shape on the surface of the fin base.

[0008] In one embodiment, the drainage groove extends from one side of the pipe hole to the windward side in a most rapid curve shape.

[0009] In one embodiment, a projected length of the drainage groove in the first direction of the fin base accounts for 10% to 20% of the length of the fin base in the first direction.

[0010] In one embodiment, the projected length of the drainage groove in the second direction of the fin base accounts for 5% to 10% of the length of the fin base in the first direction; In one embodiment, a distance between adjacent drainage grooves accounts for 10% to 25% of the length of the fin base in the first direction.

[0011] In one embodiment, the depth of the drainage groove is 0.3 mm to 1 mm, and the width of the drainage groove is 0.5 mm to 2 mm.

[0012] In one embodiment, the heat transfer section is provided with a plurality of tube holes for passing heat exchange tubes at intervals along the second direction of the fin base.

[0013] In one embodiment, the fin further includes a hydrophobic coating applied to the surface of the fin substrate, and the hydrophobic coating includes a primer coating and a top coating formed by sequential coating; wherein the primer coating includes 20wt% to 50wt% of micron-sized alumina and the remainder is epoxy resin; and / or, the top coating includes 1wt% to 5wt% of micron-sized graphene and the remainder is epoxy resin.

[0014] In one embodiment, the top coating layer includes graphene modified by perfluorosilane grafting; and / or, the top coating layer includes epoxy resin modified by perfluorosilane.

[0015] In one embodiment, the thickness of the hydrophobic coating is 1 μm to 10 μm; and / or the ratio of the thickness of the primer layer to the thickness of the top coating layer is (0.5 to 4.5):1.

[0016] In one embodiment, the method for preparing the fin comprises the following steps: S1. Providing an aluminum foil, rolling, and cutting to obtain a fin substrate; S2, coating the surface of the substrate to be treated prepared in step S1 with a primer, curing the coating to form a primer coating; coating the surface of the primer coating with a topcoat, curing the topcoat to form a hydrophobic coating; S3, stamping the fin substrate after the hydrophobic coating is formed in step S2, and forming drainage grooves on the surface of the fin substrate to obtain a fin.

[0017] In one embodiment, in step S1, the aluminum foil is rolled to a thickness of 0.085 mm to 0.105 mm; In one embodiment, in step S2, the curing temperature of the primer layer is 90° C. to 110° C.; In one embodiment, in step S2, the curing temperature of the top coating layer is 170°C to 190°C.

[0018] The present invention also provides a heat exchanger, comprising: a first header and a second header; and a plurality of groups of fins, wherein the fins are the above-mentioned fins, and the fins are spaced apart and arranged between the first header and the second header; and A plurality of groups of heat exchange tubes are provided, wherein the heat exchange tubes are passed through the tube holes of the fins, and both ends of the heat exchange tubes are respectively connected to the first header and the second header.

[0019] The technical solution of the present invention designs a heat exchanger fin with a drainage groove of a specific curve shape and a specific hydrophobic coating. The drainage groove uses the gravity of the fastest curve and the principle of fluid dynamics to accelerate the drainage of the fin surface, thereby reducing the retention of droplets; the hydrophobic coating uses the thermal conductivity of aluminum oxide and graphene and the hydrophobicity of perfluorosilane to improve the heat exchange efficiency of the fin, while improving the mechanical strength and wear resistance of the coating and reducing the surface energy of the coating, thereby significantly extending the service life of the coating and the fin. In summary, the fin designed in the present invention can, on the one hand, improve the heat exchange efficiency of the heat exchanger and reduce frosting, and on the other hand, improve the service life of the heat exchanger and maintain the heat exchange efficiency of the heat exchanger at a high level for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0021] Figure 1 Schematic diagram of the structure of the fin base in Example 1 of the present invention; Description of reference numerals: 10. Drainage section; 101. Drainage ditch; 20. Heat transfer section; 201. Pipe hole; 30. Windward side; The purpose, features and advantages of the present invention will be further described with reference to the accompanying drawings and in conjunction with the embodiments. DETAILED DESCRIPTION

[0022] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back, etc.), the directional indications are only used to explain the relative position relationship, movement status, etc. between the various components under a certain specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0024] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features limited to "first" and "second" may explicitly or implicitly include at least one of such features. In addition, if "and / or" or "and / or" appears in the full text, its meaning includes three parallel solutions. Taking "A and / or B" as an example, it includes solution A, solution B, or solutions that satisfy both A and B. In addition, the technical solutions between the various embodiments can be combined with each other, but it must be based on the ability of ordinary technicians in this field to implement. When the combination of technical solutions is mutually contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0025] The technical problem addressed by this application is that the aluminum foil fins of microchannel heat exchangers are prone to frost, resulting in reduced heat transfer efficiency and increased energy consumption. Conventional fin groove designs have low drainage efficiency, which can easily lead to residual moisture and secondary frost. Alternatively, the coating on the fin surface is weak, prone to aging and wear after long-term use, resulting in reduced heat transfer efficiency and increased secondary frost. Alternatively, the coating on the fin surface has low thermal conductivity, which affects the heat transfer efficiency of the fin.

[0026] It should be noted that the relevant technologies mainly adopt measures such as structural optimization, hydrophobic coating and composite solutions, but there are still some shortcomings. For example, in some technologies, by setting a through hole on one side of the fin, the condensed water can be discharged under the premise that the heat exchange effect is not significantly reduced, thereby avoiding the condensed water from frosting in a cold environment and affecting the heat exchange effect. However, this technology still has the problem that the drainage efficiency of the groove design on the fin surface is low and residual moisture is easy to cause secondary frost. Alternatively, in another technology, the fin is connected to the flat tube by expansion joint, so that the fin has a smoother surface, so that the condensed water can be discharged continuously from the fin, which improves the diversion effect and drainage effect of the fin, but this technology still has the problem of insufficient thermal conductivity of the coating and affects the heat exchange efficiency.

[0027] In order to solve the above technical problems, the present application proposes a fin, which includes a fin base, Figure 1The fin base includes a heat transfer section 20 and a drainage section 10 arranged along a first direction of the fin base. The drainage section 10 is arranged close to the windward side 30 of the fin base. The heat transfer section 20 is provided with a tube hole 201 for passing a heat exchange tube, and the drainage section 10 is provided with a drainage groove 101. The drainage groove 101 extends from one side of the tube hole 201 to the windward side 30 in a fastest curve shape.

[0028] It should be noted that if Figure 1 As shown, the first direction of the fin base is as follows Figure 1 As shown by arrow B in the figure, it is equivalent to Figure 1 The lateral direction of the fin base; the second direction of the fin base is as follows Figure 1 As shown by arrow A in Figure 1 The longitudinal direction of the middle fin base.

[0029] It should be noted that the main components of a commonly used fin-tube heat exchanger are heat exchange tubes and fins. Refrigerant circulates inside the heat exchange tubes for heat exchange, while the fins are located on the outside of the heat exchange tubes, enhancing air heat exchange. When the outdoor air is cold and humid, water vapor in the air tends to condense on the heat exchanger to form condensed water. If the temperature of the fin surface is below the freezing point of water, this condensed water will further condense into frost or ice, adhering to the fin surface and affecting the heat exchange efficiency of the heat exchanger. The windward side 30 of the fin base refers to the area of ​​the fin surface that the airflow first impacts, near one edge of the fin base. Compared to the leeward side of the fin base (not shown in the figure), the airflow on the windward side of the fin base has a significantly higher water vapor content.

[0030] It should be noted that the fin base in the present application includes a heat transfer section 20 and a drainage section 10 arranged along the longitudinal direction of the fin base. The drainage section 10 is closer to the windward side 30 than the heat transfer section 20, that is, the wind passing through the fin base first contacts the drainage section 10 and then contacts the heat transfer section 20. The heat transfer section 20 is provided with tube holes 201 at intervals for passing heat exchange tubes arranged in sequence along the longitudinal direction of the fin base. The drainage section 10 is provided with a drainage groove 101. Since there is more condensed water on the windward side 30 of the fin base, it is usually the part most prone to frost and clogging. By providing the drainage groove 101 in the drainage section 10 close to the windward side 30, the condensed water can be guided to the edge of the fin for rapid discharge.

[0031] It should also be noted that the drainage grooves 101 can also, to a certain extent, hinder the transfer of low temperatures from the heat transfer section 20 to the windward side 30 of the fins, thereby creating a relatively high temperature on the windward side 30 of the fins. This prevents water molecules in the airflow from condensing closer to the windward side 30 of the fins, preventing them from immediately frosting or reaching the conditions for frosting. Condensed water, therefore, quickly gathers in the drainage grooves 101 and flows more easily under the action of gravity along the drainage grooves 101 to the edge of the fins for discharge. Because the fin substrates also have a hydrophobic coating, condensed water on the fin surfaces gathers quickly and flows quickly, making it less likely to form residue and frost.

[0032] It should also be noted that the brachistochrone curve, also known as the cycloid, refers to the shortest descent path between two points at different heights in space under the action of gravity. When the drainage grooves 101 follow the brachistochrone curve, condensate flows out of the fin surfaces along the drainage grooves 101 at a faster rate, thereby increasing the condensate discharge rate on the fin surfaces and reducing condensate residue.

[0033] In one embodiment, the drainage section 10 is provided with a plurality of drainage grooves 101 spaced apart along the second direction of the fin base, and the second direction intersects the first direction. Further, the second direction and the first direction are perpendicular to each other; further, as Figure 1 As shown, the first direction is equivalent to Figure 1 The second direction is equivalent to the transverse direction of the fin base; Figure 1 The longitudinal direction of the middle fin base.

[0034] In one embodiment, the drainage groove 101 extends from one side of the tube hole 201 to the windward side 30, and the height of the drainage groove 101 in the second direction of the fin base gradually decreases. Specifically, the drainage groove 101 extends from the side of the tube hole 201 close to the windward side 30 to the windward side 30.

[0035] It should be noted that the drainage groove 101 of the drainage section 10 in the present invention extends downward from the right side of the pipe hole 201 to the windward side 30 of the fin base. The design of the drainage groove 101 can increase the contact area between the fin base and the airflow so that the water molecules in the airflow are fully condensed to prevent frosting in the heat transfer section 20; the height of the drainage groove 101 gradually decreases from the extension direction, forming a downward tilt trend, which is conducive to the formation of a drainage channel. On the one hand, it can increase the amount of condensed water accumulated in the drainage section 10, and on the other hand, it can improve the discharge efficiency of condensed water, so that the condensed water condensed on the fin surface flows to the drainage groove 101 under the action of gravity and gathers to form a water flow, which is accelerated to the edge of the fin and discharged under the action of gravity and tension.

[0036] In one embodiment, the drainage groove 101 extends along the fin base surface in an arc-like shape. It should be noted that the shape of the drainage groove 101 can be determined based on the actual configuration requirements and process conditions of the fin surface. It is also necessary to ensure that the height of the drainage groove 101 gradually decreases from the left side to the right side of the drainage section 10 to allow condensed water to accumulate and drain quickly. In other embodiments, the drainage groove 101 extending along the fin base surface can be in any of the following shapes: straight line, broken line, or wavy; this application does not impose any specific limitations.

[0037] In a preferred embodiment, when the drainage groove 101 extends in an arc shape on the surface of the fin base, the opening of the arc faces upward. Such a structural design makes it easier for water on the fin surface to gather into the drainage groove 101 when the fin is placed vertically and improves the discharge efficiency of condensed water.

[0038] In one embodiment, the transverse projection length of the drainage groove 101 on the fin base accounts for 10% to 20% of the transverse width of the fin base.

[0039] It should be noted that the drainage grooves 101 are spaced and arranged parallel to each other within the drainage section. They extend downward from the left side of the drainage section 10 to the right side. The lateral projection of the drainage grooves 101 on the fin base is approximately equal to the lateral width of the drainage section 10. By limiting the width proportion of the drainage section 10, a balance is achieved between the heat exchange efficiency and drainage efficiency of the fin. This allows for the arrangement of a sufficient number and size of drainage grooves 101 to provide effective water flow channels, while also maximizing the area of ​​the heat transfer section 20. Furthermore, concentrating the drainage grooves 101 in a region with a limited width ratio helps maintain the structural rigidity and strength of the entire fin base (particularly the heat transfer section 20).

[0040] Furthermore, in one embodiment, the longitudinal projection length of the drainage groove 101 in the fin base accounts for 5% to 10% of the transverse width of the fin base.

[0041] It should be noted that further limiting the ratio of the longitudinal projection length of the drainage groove 101 actually further limits the length range of the drainage groove 101. The drainage groove 101 needs to be of sufficient length to effectively collect or intercept condensed water on the fin surface. If the drainage groove 101 is too short, the water will flow directly across the drainage groove 101, failing to collect and guide the water, and the water will diffuse or stagnate in the longitudinal direction. If the drainage groove 101 is too long, it will cause additional disturbance and resistance to the gas flowing through it, significantly increasing the overall wind resistance of the fin and causing increased energy consumption of the fan.

[0042] In one embodiment, the distance between adjacent drainage grooves 101 accounts for 10% to 25% of the transverse width of the fin base.

[0043] It should be noted that by limiting the spacing between adjacent drainage grooves 101, the distribution density of the drainage grooves 101 in the drainage section is further limited, ensuring that the drainage grooves in the drainage section 10 can effectively gather and capture the vast majority of condensed water and promote its accelerated discharge. When the spacing between adjacent drainage grooves 101 is too large, the condensed water generated in the fin area between the two drainage grooves 101 cannot be effectively captured. The water flow may be retained or diffused before reaching the next drainage groove 101 due to gravity or airflow, causing frost. When the spacing between adjacent drainage grooves 101 is too small, on the one hand, the excessive density of the drainage grooves 101 will lead to a significant increase in airflow resistance, and on the other hand, it will also affect the structural rigidity and strength of the entire fin base.

[0044] In a specific embodiment, the transverse width of the fin base is 20 mm to 50 mm.

[0045] In a specific embodiment, the transverse projection length of the drainage groove 101 on the fin base is 2 mm to 10 mm, and the longitudinal projection length of the drainage groove 101 on the fin base is 1 mm to 5 mm.

[0046] In one embodiment, the distance between adjacent drainage grooves 101 is 2 mm to 5 mm; in a preferred embodiment, the distance between adjacent drainage grooves 101 is 3 mm to 4 mm.

[0047] In one embodiment, the depth of the drainage groove 101 is 0.3 mm to 1 mm, and the width of the drainage groove 101 is 0.5 mm to 2 mm.

[0048] In a preferred embodiment, the depth of the drainage groove 101 is 0.4 mm to 0.8 mm, and the width of the drainage groove 101 is 0.8 mm to 1.5 mm.

[0049] It should be noted that by limiting the depth and width of the drainage groove 101, the volume and surface area of ​​the drainage groove 101 are further limited. When the width of the drainage groove 101 is too narrow or the depth is insufficient, water flow is easily retained in the groove to form a water film, reducing drainage efficiency; when the width of the drainage groove 101 is too wide, it is easy to cause condensation water residue, and it is easy to cause secondary frost to block the groove in a low temperature environment; when the depth of the drainage groove 101 is too deep, it will increase drainage resistance and easily cause condensation water residue.

[0050] In one embodiment, the heat transfer section is provided with a plurality of holes spaced longitudinally along the fin base for inserting heat exchange tubes. This application imposes no particular restrictions on the spacing and shape of the holes; any hole shape that meets the basic functional requirements of the fins is acceptable. Preferably, the holes correspond to the flat tubes.

[0051] In one embodiment, the fin further includes a hydrophobic coating applied to the surface of the fin substrate, and the hydrophobic coating includes a base coating and a top coating formed by sequential coating; wherein the base coating includes 20wt% to 50wt% of micron-sized aluminum oxide and the remainder is epoxy resin; the top coating includes 1wt% to 5wt% of micron-sized graphene and the remainder is epoxy resin.

[0052] It should be noted that the primer and topcoat are formed on the surface of the aluminum foil fin substrate in sequence, and micron-sized alumina is added as the main filler in the primer. On the one hand, alumina has a high Mohs hardness and a regular shape. After being mixed with epoxy resin and coated on the aluminum foil surface, it can play a good anchoring role, thereby ensuring the adhesion of the primer; on the other hand, the thermal expansion coefficient of alumina (7×10 -6 / ℃~8×10 -6 / ℃) is close to the thermal expansion coefficient of aluminum foil (23×10 -6 / ℃), which can effectively reduce the interface stress cracking caused by the hot and cold cycles of the fins.

[0053] It can be understood that, in addition to epoxy resin and corresponding fillers, the base coating and top coating in this application also include a small amount of wetting agents, dispersants, stabilizers, defoaming agents and other additives. These are necessary additives required in the prior art to achieve beautiful, dense and other effects when forming the coating. Since the research focus of this application is not on the above-mentioned substances, they will not be elaborated on.

[0054] It should also be noted that graphene is a layered material with extremely high thermal conductivity, which can significantly improve heat exchange efficiency; and graphene has good conductivity, which enables the surface coating to form a conductive network, thereby eliminating the surface static electricity of the hydrophobic coating and preventing the hydrophobicity of the hydrophobic coating from being destroyed due to the adsorption of dust.

[0055] In one embodiment, the diameter of the graphene sheet ranges from 1 μm to 8 μm; in a preferred embodiment, the diameter of the graphene sheet ranges from 1 μm to 3 μm.

[0056] It should be noted that the sheet diameter of graphene refers to the size of graphene as a layered material in the direction of the layered plane, while the size of single-layer, double-layer and few-layer graphene in the third direction is usually more than ten nanometers or even smaller; the graphene in the topcoat of the present application is mainly stacked in a two-dimensional form, and multiple layers of graphene can be stacked within the limit of the coating thickness.

[0057] In one embodiment, the topcoat further comprises perfluorosilane.

[0058] In a specific embodiment, the amount of perfluorosilane in the topcoat layer is 0.5 wt % to 1.8 wt %.

[0059] In a specific embodiment, the perfluorosilane includes at least one of trifluoropropyltrimethoxysilane (TFPTMS), perfluorobutylethyltrimethoxysilane (PFBTES), perfluorohexylethyltrimethoxysilane (PFHTMS), perfluorohexylethyltriethoxysilane (PFHTES), 1H,1H,2H,2H-perfluorooctyltrimethoxysilane (PFOTMS), 1H,1H,2H,2H-perfluorooctyltriethoxysilane (PFOTES), perfluorodecyltrimethoxysilane (PFDTMS), heptadecafluoro-1,1,2,2-tetrahydrodecyltrimethoxysilane (F17-TMS), tris(perfluorohexylethyl)methoxysilane (Tris-PFHE), and perfluorotetradecylethyltriethoxysilane (PFTETES).

[0060] It should be noted that perfluorosilane is a class of organosilicon compounds containing both perfluoroalkyl chains and hydrolyzable silane groups in their molecular structure; including but not limited to those with the general formula Rf-(CH2) n The organosilicon compound of Si(OR)3, the perfluorosilane in this application can also be an organosilicon compound containing other groups as well as the above-mentioned perfluoroalkyl chain and hydrolyzable silane group, including but not limited to perfluoropolyether silane, perfluoroalkylethyl isocyanate silane, perfluorosilane quaternary ammonium salt, perfluorooctyltrichlorosilane and other organosilicon compounds.

[0061] In a specific embodiment, the top coating layer includes graphene modified by perfluorosilane grafting. And / or, in a specific embodiment, the top coating layer includes epoxy resin modified by perfluorosilane.

[0062] It should be noted that the perfluorosilane added to the topcoat is a key chemical modification method for improving the hydrophobicity and durability of the coating. By hydrolyzing the silane group of perfluorosilane to produce silanol groups, the silanol groups can react with hydroxyl groups or epoxy groups in the epoxy resin to form bonds, resulting in a perfluorosilane-modified epoxy resin. And / or, the silanol groups can react with hydroxyl groups or carboxyl groups on the surface of the graphene sheet to form bonds, resulting in perfluorosilane-grafted graphene. By adopting the above-mentioned technical means, the surface energy of the hydrophobic coating can be further reduced, the water contact angle of the hydrophobic coating can be increased, and the bonding between the graphene and the epoxy resin in the topcoat is promoted, thereby improving the wear resistance of the topcoat.

[0063] In one embodiment, the thickness of the hydrophobic coating is 1 μm-10 μm.

[0064] In a specific embodiment, the ratio of the thickness of the primer layer to the thickness of the top coating layer is (0.5-4.5):1.

[0065] It should be noted that by limiting the ratio of the thickness of the primer layer to the thickness of the topcoat layer to a specific range, a stable bond between the primer layer and the fin substrate is achieved on the one hand, and a stable bond between the primer layer and the topcoat is achieved on the other hand. When the ratio of the thickness of the primer layer to the thickness of the topcoat layer is less than 0.5:1, the topcoat layer is too thick and the primer layer is too thin, resulting in insufficient anchoring force of the primer layer on the fin substrate, causing the hydrophobic coating to easily peel off from the surface of the fin substrate. When the ratio of the thickness of the primer layer to the thickness of the topcoat layer is greater than 4.5:1, the primer layer is too thick, which is not conducive to the thermal conductivity of the entire fin.

[0066] The present invention also provides a method for preparing a fin, comprising the following steps: S1. Providing an aluminum foil, rolling, and cutting to obtain a fin substrate; S2, coating the surface of the substrate to be treated prepared in step S1 with a primer, curing the coating to form a primer coating; coating the surface of the primer coating with a topcoat, curing the topcoat to form a hydrophobic coating; S3, stamping the fin substrate after the hydrophobic coating is formed in step S2 and forming drainage grooves on the surface of the fin substrate to obtain a fin.

[0067] In one embodiment, in step S1 , the aluminum foil is rolled to a thickness of 0.085 mm to 0.105 mm.

[0068] In one embodiment, in step S2, the curing temperature of the primer layer is 90°C to 110°C.

[0069] In one embodiment, in step S2, the curing temperature of the top coating layer is 170°C to 190°C.

[0070] The present invention also provides a heat exchanger, comprising: a first header and a second header; and Multiple groups of fins, the fins are the fins described above in this application, and the multiple groups of fins are spaced apart and arranged between the first header and the second header; and Multiple groups of heat exchange tubes are respectively passed through different tube holes of the fins, and both ends of the heat exchange tubes are respectively connected to the first header and the second header.

[0071] The present invention is further described below by means of specific examples: The raw materials used in the embodiments of the present invention are all commercially available, and the present invention does not impose any restrictions on the sources of the raw materials.

[0072] Example 1 The fin in Example 1 includes a fin substrate and a hydrophobic coating applied on the surface of the fin substrate; wherein, referring to Figure 1The fin base includes a heat transfer section 20 and a drainage section 10 arranged along the longitudinal direction of the fin base. The heat transfer section 20 is provided with tube holes 201 at intervals along the longitudinal direction of the fin base, and the drainage section 10 is provided with drainage grooves 101 at intervals along the longitudinal direction of the fin base.

[0073] The drainage grooves extend downward from the left side of the drainage section to the right side in a most rapid curve. The fin base has a transverse width of approximately 40 mm, a transverse projection of the drainage grooves on the fin base of approximately 5 mm, and a longitudinal projection of the drainage grooves on the fin base of approximately 3 mm. Adjacent drainage grooves are spaced 5 mm apart. The depth and width of the drainage grooves are approximately 0.8 mm.

[0074] The hydrophobic coating on the surface of the fin substrate includes a topcoat and a bottomcoat, wherein the raw materials of the topcoat include: Graphene (1μm~3μm): 5wt%; PFOTES: 0.9wt%; dispersant (BYK-163): 0.5wt%; and the balance bisphenol A epoxy resin.

[0075] Accordingly, the preparation process of the coating for preparing the topcoat layer comprises the following steps: One-fifth of the epoxy resin and PFOTES were mixed and stirred for 15 minutes to prepare a modified liquid. Graphene, dispersant, and the remaining epoxy resin were mixed and dispersed at high speed (2000 rpm) for 30 minutes. The modified liquid was then added, dispersed at high speed (2000 rpm) for 30 minutes, and vacuum degassing was performed to complete the preparation.

[0076] The raw materials for the base coat include: Micron-sized alumina (1μm~2μm): 30wt%; dispersant (BYK-163): 1wt%; and the balance bisphenol A epoxy resin.

[0077] Accordingly, the preparation process of the coating for preparing the base coat comprises the following steps: The dried micron-sized alumina, dispersant and bisphenol A epoxy resin were mixed at a low speed (200 rpm) for 10 minutes and vacuum degassed to complete the preparation.

[0078] The method for preparing the fin in Example 1 comprises the following steps: S1. Provide an aluminum foil, roll it to a thickness of 0.085 mm to 0.105 mm, and cut it to obtain a fin substrate; S2, coating the surface of the prepared fin substrate with a primer, curing it at 100° C. for 15 minutes to form a primer coating; coating the surface of the primer coating with a topcoat, curing it at 180° C. for 30 minutes to form a topcoat, thereby forming a hydrophobic coating; S3. Punching the fin substrate after forming the hydrophobic coating and forming drainage grooves with corresponding parameters on the surface of the fin substrate to obtain the fin.

[0079] The fins in Example 1 are replaced with the fins of the heat exchanger of the air conditioner of the corresponding model in Comparative Example 1 to obtain the heat exchanger in Example 1.

[0080] Comparative Example 1 Comparative Example 1 is based on Example 1. Comparative Example 1 is a commercially available air conditioner of model KFR48GW. The heat exchanger of the air conditioner uses hydrophilic aluminum foil, and the fastest curve drainage groove in this application is not provided on the fin surface.

[0081] Performance testing (1) The free low-temperature heating capacity (W) and the free low-temperature heating-defrosting cycle (min) of the heat exchangers in Example 1 and Comparative Example 1 were measured with reference to the standard GB / T 7725-2022 "Room Air Conditioners"; wherein the indoor operating condition was set to a dry-bulb temperature of 20°C / wet-bulb temperature of 15°C, and the outdoor operating condition was set to a dry-bulb temperature of 2°C / wet-bulb temperature of 1°C.

[0082] (2) The wear resistance of the hydrophobic coating of the fin in Example 1 was measured with reference to the ASTM-D968 standard. The measurement results are shown in Table 1.

[0083] Table 1

[0084] By analyzing the data in Table 1, it can be found that compared with heat exchangers and refrigeration equipment with conventional fin structures and conventional fin surface morphologies, the refrigeration equipment corresponding to the fins prepared in this application has a significantly higher free low-temperature heating capacity, which is about 10% higher; the free low-temperature heating-defrosting cycle is also significantly longer, which is about 70% higher.

[0085] The hydrophobic coating of the fin prepared in the present application has undergone 600 wear cycles under the test conditions corresponding to standard ASTM-D968, and the hydrophobicity and thermal conductivity have not shown a significant decrease; it can be seen that the hydrophobic coating of the fin prepared in the present application has excellent strength, adhesion and stability.

[0086] In summary, the fins designed in the present invention can, on the one hand, improve the heat exchange efficiency of the heat exchanger and reduce frosting, and on the other hand, increase the service life of the heat exchanger and maintain the heat exchange efficiency of the heat exchanger at a high level for a long time.

[0087] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformation made by utilizing the contents of the present invention's description and drawings under the technical concept of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. A fin, characterized in that: The fin includes a fin base, the fin base includes a heat transfer section and a drainage section arranged along a first direction of the fin base, and the drainage section is arranged close to the windward side of the fin base; The heat transfer section is provided with a tube hole for passing a heat exchange tube, and the drainage section is provided with a drainage groove; The drainage groove extends from one side of the pipe hole to the windward side in a most rapid curve shape.

2. The fin according to claim 1, wherein The drainage section is provided with a plurality of drainage grooves at intervals along a second direction of the fin base, and the second direction intersects with the first direction.

3. The fin according to claim 1, wherein The drainage groove extends from one side of the tube hole to the windward side, and the height of the drainage groove in the second direction of the fin base gradually decreases.

4. The fin according to claim 1, wherein The drainage groove extends in an arc shape on the surface of the fin base.

5. The fin according to claim 2, wherein: The projected length of the drainage groove in the first direction of the fin base accounts for 10% to 20% of the length of the fin base in the first direction; and / or, the projected length of the drainage groove in the second direction of the fin base accounts for 5% to 10% of the length of the fin base in the first direction; And / or, the distance between adjacent drainage grooves accounts for 10% to 25% of the length of the fin base in the first direction.

6. The fin according to claim 1, wherein The depth of the drainage groove is 0.3mm~1mm; And / or, the width of the drainage groove is 0.5mm~2mm.

7. The fin according to claim 1, wherein The heat transfer section is provided with a plurality of tube holes for passing heat exchange tubes at intervals along the second direction of the fin base.

8. The fin according to claim 1, wherein The fin further comprises a hydrophobic coating applied on the surface of the fin substrate, wherein the hydrophobic coating comprises a base coating and a top coating formed by sequential coating; The primer layer comprises 20 wt % to 50 wt % of micron-sized aluminum oxide and the remainder is epoxy resin; and / or the top coating layer comprises 1 wt % to 5 wt % of micron-sized graphene and the remainder is epoxy resin.

9. The fin according to claim 8, wherein The top coating layer includes graphene treated by perfluorosilane grafting modification; And / or, the top coating layer includes a perfluorosilane-modified epoxy resin.

10. The fin according to claim 8, wherein The thickness of the hydrophobic coating is 1 μm to 10 μm; And / or, the ratio of the thickness of the primer layer to the thickness of the top coating layer is (0.5-4.5):

1.

11. A method for preparing a fin according to any one of claims 1 to 10, characterized in that: The preparation method of the fin comprises the following steps: S1. Providing an aluminum foil, rolling, and cutting to obtain a fin substrate; S2, coating the surface of the substrate to be treated prepared in step S1 with a primer, curing the coating to form a primer coating; coating the surface of the primer coating with a topcoat, curing the topcoat to form a hydrophobic coating; S3, stamping the fin substrate after the hydrophobic coating is formed in step S2, and forming drainage grooves on the surface of the fin substrate to obtain a fin.

12. The method for preparing a fin according to claim 11, wherein: In step S1, the aluminum foil is rolled to a thickness of 0.085 mm to 0.105 mm; And / or, in step S2, the curing temperature of the primer layer is 90° C. to 110° C.; And / or, in step S2, the curing temperature of the topcoat layer is 170°C to 190°C.

13. A heat exchanger, characterized in that: The heat exchanger comprises: a first header and a second header; and a plurality of groups of fins, wherein the fins are the fins according to any one of claims 1 to 10, and the fins are spaced apart and arranged between the first header and the second header; and A plurality of groups of heat exchange tubes are provided, wherein the heat exchange tubes are passed through the tube holes of the fins, and both ends of the heat exchange tubes are respectively connected to the first header and the second header.

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