Fin and method for manufacturing the same, heat exchanger

Abstract

The application discloses a fin and 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 coated on the surface of the fin base body. The fin base body comprises a heat transfer section and a drainage section arranged along the first direction of the fin base body. 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 penetrating a heat exchange pipe. The drainage section is provided with a drainage groove. The fin designed in the application can improve the heat exchange efficiency of the heat exchanger and reduce frost formation on one hand, and can 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 on the other hand.

Description

Technical Field

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

[0002] Microchannel heat exchangers are widely used in heat exchange equipment in low-temperature and high-humidity environments such as air conditioners and heat pumps. Under these conditions, the aluminum foil fins of microchannel heat exchangers are prone to frosting, leading to decreased heat exchange efficiency and increased energy consumption. Related technologies suffer from low drainage efficiency of the heat exchanger fins, resulting in residual moisture and frosting; poor thermal conductivity of the fin coating, further reducing heat exchange efficiency; or insufficient mechanical strength or resistance to thermal shock of the fin coating, leading to surface defects that also affect heat exchange. Therefore, there is an urgent need for a fin structure solution that enables rapid defrosting and efficient heat exchange to improve heat exchanger performance. Summary of the Invention

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

[0004] To achieve the above objectives, the present invention proposes a fin, the fin comprising a fin substrate, the fin substrate comprising a heat transfer section and a drainage section arranged along a first direction of the fin substrate, the drainage section being disposed near the windward side of the fin substrate; the heat transfer section having a pipe hole for inserting a heat exchange tube, the drainage section having a drainage groove; the drainage groove extending from one side of the pipe hole to the windward side in a steepest curve shape.

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

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

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

[0008] In one embodiment, the drainage ditch extends in a steepest curve from one side of the pipe hole to the windward side.

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

[0010] In one embodiment, the projected length of the drainage groove in the second direction of the fin substrate accounts for 5% to 10% of the length of the fin substrate in the first direction;

[0011] In one embodiment, the spacing between adjacent drainage grooves is 10% to 25% of the length of the fin substrate in a first direction.

[0012] In one embodiment, the depth of the drainage ditch is 0.3mm to 1mm, and the width of the drainage ditch is 0.5mm to 2mm.

[0013] In one embodiment, the heat transfer section is provided with a plurality of tube holes spaced apart along the second direction of the fin substrate for passing through heat exchange tubes.

[0014] In one embodiment, the fin further includes a hydrophobic coating applied to the surface of the fin substrate, the hydrophobic coating comprising a base coating and a top coating formed sequentially; wherein the base coating comprises 20wt% to 50wt% of micron-sized alumina and the balance being epoxy resin; and / or, the top coating comprises 1wt% to 5wt% of micron-sized graphene and the balance being epoxy resin.

[0015] In one embodiment, the topcoat comprises graphene grafted with perfluorosilane; and / or, the topcoat comprises epoxy resin modified with perfluorosilane.

[0016] In one embodiment, the thickness of the hydrophobic coating is 1 μm to 10 μm; and / or, the ratio of the thickness of the base coating to the thickness of the top coating is (0.5 to 4.5):1.

[0017] In one embodiment, the method for preparing the fins includes the following steps:

[0018] S1. Provide an aluminum foil, roll and cut it to obtain a fin substrate;

[0019] S2. Apply a primer to the surface of the substrate to be treated obtained in step S1, and cure it to form a base coating; apply a topcoat to the surface of the base coating, and cure it to form a topcoat, forming a hydrophobic coating.

[0020] S3. The fin substrate after the hydrophobic coating is formed in step S2 is stamped and formed, and drainage grooves are formed on the surface of the fin substrate to obtain fins.

[0021] In one embodiment, in step S1, the aluminum foil is rolled to a thickness of 0.085 mm to 0.105 mm;

[0022] In one embodiment, in step S2, the curing temperature of the base coating is 90°C to 110°C;

[0023] In one embodiment, in step S2, the curing temperature of the surface coating is 170°C to 190°C.

[0024] The present invention also proposes a heat exchanger comprising:

[0025] First manifold and second manifold; and

[0026] Multiple sets of fins, wherein the fins are as described above, and the fins are spaced apart between the first manifold and the second manifold; and

[0027] Multiple sets of heat exchange tubes are provided, the heat exchange tubes are inserted through the tube holes of the fins, and the two ends of the heat exchange tubes are respectively connected to the first manifold and the second manifold.

[0028] The technical solution of this invention designs a heat exchanger fin with both a drainage groove of a specific curved shape and a specific hydrophobic coating. The drainage groove utilizes the principles of gravity and fluid dynamics based on the steepest curve to accelerate drainage from the fin surface, thereby reducing droplet retention. The hydrophobic coating utilizes the thermal conductivity of alumina and graphene, as well as the hydrophobicity of perfluorosilane, to improve the heat exchange efficiency of the fin. Simultaneously, it enhances the mechanical strength and wear resistance of the coating and reduces its surface energy, significantly extending the service life of both the coating and the fin. In summary, the fins designed in this invention can improve the heat exchanger's heat exchange efficiency and reduce frost formation, while also extending the heat exchanger's service life and maintaining a high level of heat exchange efficiency over a long period. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0030] Figure 1 This is a schematic diagram of the structure of the finned substrate in Embodiment 1 of the present invention;

[0031] Explanation of reference numerals in the attached figures:

[0032] 10. Drainage section; 101. Drainage ditch; 20. Heat transfer section; 201. Pipe hole; 30. Windward side;

[0033] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0035] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0036] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0037] The technical problem addressed by this application is that the aluminum foil fins of microchannel heat exchangers are prone to frosting, leading to decreased heat exchange efficiency and increased energy consumption. Traditional fin groove designs have low drainage efficiency; they are prone to residual moisture leading to secondary frosting; or the coating strength on the fin surface is poor, and after long-term use, it is prone to aging and wear, resulting in low heat exchange efficiency and an increased rate of secondary frosting; or the coating on the fin surface has low thermal conductivity, affecting the heat exchange efficiency of the fins.

[0038] It should be noted that the relevant technologies mainly employ structural optimization, hydrophobic coatings, and composite solutions, but some shortcomings still exist. For example, some technologies use through-holes on one side of the fins to drain condensate without significantly reducing heat exchange efficiency, preventing condensate from frosting in cold environments and affecting heat exchange performance. However, this technology still suffers from low drainage efficiency due to the grooved design on the fin surface and the tendency for residual moisture to cause secondary frosting. Alternatively, another technology uses an expansion joint between the fins and a flat tube to create a smoother fin surface, allowing condensate to drain continuously from the fins, improving both flow conduction and drainage. However, this technology still suffers from insufficient thermal conductivity of the coating, affecting heat exchange efficiency.

[0039] To address the aforementioned technical problems, this application proposes a fin, which includes a fin substrate, as shown in the reference. Figure 1 The fin substrate includes a heat transfer section 20 and a drainage section 10 arranged along a first direction of the fin substrate. The drainage section 10 is located near the windward side 30 of the fin substrate. The heat transfer section 20 is provided with a pipe hole 201 for passing through 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 pipe hole 201 to the windward side 30 in a steepest curve shape.

[0040] It should be noted that, as Figure 1 As shown, the first direction of the fin substrate is as follows: Figure 1 Arrow B in the image represents... Figure 1 The transverse direction of the fin matrix; the second direction of the fin matrix as follows Figure 1 Arrow A in the image represents... Figure 1 The longitudinal direction of the middle fin substrate.

[0041] It should be noted that commonly used finned tube heat exchangers mainly consist of heat exchange tubes and fins. Refrigerant flows inside the heat exchange tubes for heat exchange, while the fins, located on the outside of the tubes, enhance air heat exchange. When outdoor air is cold and humid, water vapor in the air easily condenses on the heat exchanger, forming condensate. If the temperature of the fin surface is below the freezing point of water, this condensate will further condense into frost or ice, adhering to the fin surface and affecting the heat exchanger's efficiency. The windward side 30 of the fin substrate refers to the area on the fin surface that the airflow first impacts, near the edge of the fin substrate. Compared to the leeward side of the fin substrate (not shown in the diagram), the water vapor content of the airflow on the windward side of the fin substrate is significantly higher.

[0042] It should be noted that the fin substrate in this application includes a heat transfer section 20 and a drainage section 10 arranged longitudinally along the fin substrate. The drainage section 10 is closer to the windward side 30 than the heat transfer section 20, meaning that the air passing through the fin substrate first contacts the drainage section 10 and then the heat transfer section 20. The heat transfer section 20 is provided with pipe holes 201 at intervals for passing through heat exchange tubes arranged sequentially along the longitudinal direction of the fin substrate. The drainage section 10 is provided with drainage grooves 101. Since the windward side 30 of the fin substrate has more condensate, it is usually the part most prone to frost and blockage. By providing drainage grooves 101 in the drainage section 10 near the windward side 30, the condensate can be guided to flow to the edge of the fin and discharged quickly.

[0043] It should also be noted that the drainage groove 101 can, to a certain extent, hinder the transfer of the low temperature of 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 causes water molecules in the airflow to condense closer to the windward side 30 of the fins without immediately frosting or reaching the conditions for frosting, thus producing condensate that quickly collects in the drainage groove 101 and is more easily discharged to the edge of the fins under the action of gravity. Because there is also a hydrophobic coating on the surface of the fin substrate, the condensate on the fin surface accumulates quickly and flows at a fast speed, making it less likely to form residue and frost.

[0044] It should also be noted that the steepest curve, or cycloid, refers to the shortest descent path between two points at different heights in space under the influence of gravity. When the drainage ditch 101 exhibits a steepest curve, the condensate is discharged from the fin surface more quickly along the drainage ditch 101, which can improve the condensate discharge speed from the fin surface and reduce condensate residue.

[0045] In one embodiment, the drainage section 10 is provided with a plurality of drainage grooves 101 spaced apart along a second direction of the fin substrate, the second direction intersecting 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 transverse direction of the middle fin matrix; the second direction is equivalent to Figure 1 The longitudinal direction of the middle fin substrate.

[0046] In one embodiment, the drainage ditch 101 extends from one side of the pipe hole 201 to the windward side 30, and the height of the drainage ditch 101 gradually decreases in the second direction of the fin substrate. Specifically, the drainage ditch 101 extends from the side of the pipe hole 201 near the windward side 30 to the windward side 30.

[0047] It should be noted that the drainage ditch 101 of the drainage section 10 in this invention extends downward from the right side of the pipe hole 201 to the windward side 30 of the fin substrate. The design of the drainage ditch 101 can increase the contact area between the fin substrate and the airflow, thereby allowing water molecules in the airflow to fully condense and preventing frost formation in the heat transfer section 20. The height of the drainage ditch 101 gradually decreases from the extension direction, forming a downward sloping trend, which is conducive to forming a drainage channel. On the one hand, it can increase the amount of condensate accumulation in the drainage section 10, and on the other hand, it can improve the condensate discharge efficiency. The condensate condensed on the fin surface flows to the drainage ditch 101 under the action of gravity and accumulates to form a water flow. Under the action of gravity and tension, it accelerates to the edge of the fin and is discharged.

[0048] In one embodiment, the drainage groove 101 extends in an arc shape on the surface of the fin substrate. It should be noted that the extension shape of the drainage groove 101 can be determined according to the actual installation requirements and process conditions of the fin surface. Simultaneously, it is necessary to ensure that the height of the drainage groove 101 gradually decreases from the left to the right side of the drainage section 10, so that condensate can quickly accumulate and drain. In another embodiment, the shape of the drainage groove 101 extending on the surface of the fin substrate can be any of a straight line, a broken line, or a wave shape; this application does not impose any specific limitations.

[0049] In a preferred embodiment, when the shape of the drainage groove 101 extending on the surface of the fin substrate is arc-shaped, the opening of the arc faces upward. This structural design makes it easier for water on the surface of the fin to collect in the drainage groove 101 when the fin is placed vertically, and improves the drainage efficiency of condensate.

[0050] In one embodiment, the lateral projection length of the drainage groove 101 on the fin substrate accounts for 10% to 20% of the lateral width of the fin substrate.

[0051] It should be noted that the drainage channels 101 are spaced at certain intervals and arranged in parallel within the drainage section. The drainage channels 101 extend downwards from the left side of the drainage section 10 to the right side of the drainage section 10. The lateral projection length of the drainage channels 101 on the fin substrate can be approximately equal to the lateral width of the drainage section 10. By limiting the width ratio of the drainage section 10, a balance is achieved between the heat transfer efficiency and drainage efficiency of the fins. On the one hand, a sufficient number and size of drainage channels 101 can be arranged to provide effective water flow channels; on the other hand, the area of ​​the heat transfer section 20 can be preserved to the maximum extent. In addition, concentrating the drainage channels 101 in an area with a limited width ratio helps to maintain the structural rigidity and strength of the entire fin substrate (especially the heat transfer section 20).

[0052] Furthermore, in one embodiment, the longitudinal projection length of the drainage groove 101 on the fin substrate accounts for 5% to 10% of the transverse width of the fin substrate.

[0053] It should be noted that by further limiting the proportion of the longitudinal projection length of the drainage ditch 101, the length range of the drainage ditch 101 is actually further limited. The drainage ditch 101 needs to be long enough to effectively collect or intercept condensate on the fin surface. If the length of the drainage ditch 101 is too short, the water flow will directly cross over the drainage ditch 101, failing to collect and guide the flow, and the water flow will diffuse or stagnate longitudinally. If the length of the drainage ditch 101 is too long, it will generate additional disturbance and resistance to the flowing gas, significantly increasing the overall wind resistance of the fins and leading to increased fan energy consumption.

[0054] In one embodiment, the spacing between adjacent drainage grooves 101 accounts for 10% to 25% of the lateral width of the fin substrate.

[0055] It should be noted that limiting the spacing between adjacent drainage channels 101 further limits the distribution density of drainage channels 101 in the drainage section, ensuring that the drainage channels in the drainage section 10 can effectively collect and capture most of the condensate and promote its accelerated discharge. When the spacing between adjacent drainage channels 101 is too large, the condensate generated in the fin area between two drainage channels 101 cannot be effectively captured, and the water flow may stagnate or diffuse before reaching the next drainage channel 101 due to gravity or airflow, resulting in frost. When the spacing between adjacent drainage channels 101 is too small, on the one hand, the excessive density of drainage channels 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 substrate.

[0056] In one specific embodiment, the lateral width of the fin substrate is 20mm to 50mm.

[0057] In one specific embodiment, the lateral projection length of the drainage groove 101 on the fin substrate is 2mm~10mm, and the longitudinal projection length of the drainage groove 101 on the fin substrate is 1mm~5mm.

[0058] In one embodiment, the spacing between adjacent drainage ditches 101 is 2mm to 5mm; in a preferred embodiment, the spacing between adjacent drainage ditches 101 is 3mm to 4mm.

[0059] In one embodiment, the depth of the drainage ditch 101 is 0.3mm to 1mm, and the width of the drainage ditch 101 is 0.5mm to 2mm.

[0060] In a preferred embodiment, the depth of the drainage ditch 101 is 0.4mm to 0.8mm, and the width of the drainage ditch 101 is 0.8mm to 1.5mm.

[0061] It should be noted that by limiting the depth and width of the drainage ditch 101, the volume and surface area of ​​the drainage ditch 101 are further restricted. When the width of the drainage ditch 101 is too narrow or the depth is insufficient, water flow is prone to stagnation in the ditch, forming a water film and reducing drainage efficiency. When the width of the drainage ditch 101 is too wide, condensation water is prone to remain, and in low-temperature environments, it is prone to secondary frost formation and blockage of the ditch. When the depth of the drainage ditch 101 is too deep, it will increase drainage resistance and is prone to condensation water residue.

[0062] In one embodiment, the heat transfer section is provided with a plurality of tube holes spaced at intervals along the longitudinal direction of the fin substrate for inserting heat exchange tubes. This application does not impose special restrictions on the spacing and shape of the tube holes, as long as they conform to the basic functional requirements of the fins. Preferably, the tube holes are those corresponding to flat tubes.

[0063] In one embodiment, the fin further includes a hydrophobic coating applied to the surface of the fin substrate. The hydrophobic coating includes a base coating and a top coating formed sequentially. The base coating includes 20wt% to 50wt% of micron-sized alumina and the balance of epoxy resin. The top coating includes 1wt% to 5wt% of micron-sized graphene and the balance of epoxy resin.

[0064] It should be noted that by sequentially forming a base coating and a top coating on the surface of the fin substrate made of aluminum foil, and by adding micron-sized alumina as the main filler to the base coating, the alumina has two advantages: firstly, its high Mohs hardness and regular shape, when mixed with epoxy resin and applied to the aluminum foil surface, can provide good anchoring, thus ensuring the adhesion of the base coating; secondly, the coefficient of thermal expansion of alumina (7×10⁻⁶) is also considered. -6 / ℃~8×10 -6 The coefficient of thermal expansion (°C) is close to that of aluminum foil (23×10⁻⁶). -6 / ℃), which can effectively reduce interfacial stress cracking caused by fin thermal cycling.

[0065] It is understood that, in addition to epoxy resin and corresponding fillers, the primer and topcoat in this application also include a small amount of wetting agents, dispersants, stabilizers, defoamers and other additives. These are necessary additives used in the prior art to achieve aesthetic and dense effects when forming coatings. Since the research focus of this application is not on the above substances, they will not be elaborated on further.

[0066] It should also be noted that graphene is a layered material with extremely high thermal conductivity, which can significantly improve heat exchange efficiency; moreover, graphene has good electrical conductivity, which enables the surface coating to form a conductive network, thereby eliminating surface static electricity of the hydrophobic coating and preventing the hydrophobicity of the hydrophobic coating from being damaged due to dust adsorption.

[0067] In one embodiment, the graphene sheet diameter ranges from 1 μm to 8 μm; in a preferred embodiment, the graphene sheet diameter ranges from 1 μm to 3 μm.

[0068] 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-dimensional direction is usually tens of nanometers or even smaller; in the surface coating of this application, graphene is mainly stacked in a two-dimensional form, and multiple layers of graphene can be stacked under the limitation of coating thickness.

[0069] In one embodiment, the topcoat also includes a perfluorosilane.

[0070] In one specific embodiment, the amount of perfluorosilane used in the topcoat is 0.5wt% to 1.8wt%.

[0071] In one 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).

[0072] It should be noted that perfluorosilanes are a class of organosilicon compounds whose molecular structure contains both a perfluoroalkyl chain and a hydrolyzable silane group; including but not limited to those with the general structural formula Rf-(CH2). n The organosilicon compounds of Si(OR)3, the perfluorosilanes in this application may also be organosilicon compounds containing other groups as well as the above-mentioned perfluoroalkyl chains and hydrolyzable silane groups, including but not limited to perfluoropolyether silanes, perfluoroalkyl ethyl isocyanate silanes, perfluorosilane quaternary ammonium salts, perfluorooctyltrichlorosilanes and other organosilicon compounds.

[0073] In one specific embodiment, the topcoat comprises graphene grafted with perfluorosilane. And / or, in one specific embodiment, the topcoat comprises epoxy resin modified with perfluorosilane.

[0074] It should be noted that the addition of perfluorosilanes to the topcoat is a key chemical modification method to improve the hydrophobicity and durability of the coating. This is achieved by hydrolyzing the silane groups of the perfluorosilane to obtain silanol groups. These silanol groups can react with hydroxyl or epoxy groups in the epoxy resin to form bonds, resulting in perfluorosilane-modified epoxy resin. And / or, the silanol groups can react with hydroxyl or carboxyl groups on the surface of graphene sheets to form bonds, resulting in perfluorosilane-grafted modified graphene. By employing these techniques, 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 graphene and epoxy resin in the topcoat can be promoted, thereby improving the wear resistance of the topcoat.

[0075] In one embodiment, the thickness of the hydrophobic coating is 1 μm to 10 μm.

[0076] In one specific embodiment, the ratio of the thickness of the base coating to the thickness of the top coating is (0.5~4.5):1.

[0077] It should be noted that by limiting the ratio of the thickness of the base coating to the thickness of the top coating within a specific range, stable bonding between the base coating and the fin substrate, as well as stable bonding between the base coating and the top coating, is achieved. When the ratio of the base coating thickness to the top coating thickness is less than 0.5:1, the top coating is too thick and the base coating is too thin, resulting in insufficient anchoring force of the base coating to the fin substrate, which makes the hydrophobic coating prone to peeling off from the fin substrate surface. When the ratio of the base coating thickness to the top coating thickness is greater than 4.5:1, the base coating is too thick, which is detrimental to the overall thermal conductivity of the fin.

[0078] This invention also proposes a method for preparing fins, comprising the following steps:

[0079] S1. Provide an aluminum foil, roll and cut it to obtain a fin substrate;

[0080] S2. Apply a primer to the surface of the substrate to be treated obtained in step S1, and cure it to form a base coating; apply a topcoat to the surface of the base coating, and cure it to form a topcoat, forming a hydrophobic coating.

[0081] S3. The fin substrate after the hydrophobic coating is formed in step S2 is stamped and formed with drainage grooves on the surface of the fin substrate to obtain fins.

[0082] In one embodiment, in step S1, the aluminum foil is rolled to a thickness of 0.085 mm to 0.105 mm.

[0083] In one embodiment, in step S2, the curing temperature of the base coating is 90°C to 110°C.

[0084] In one embodiment, in step S2, the curing temperature of the topcoat is 170°C to 190°C.

[0085] The present invention also proposes a heat exchanger comprising:

[0086] First manifold and second manifold; and

[0087] Multiple sets of fins, the fins being those described above in this application, are spaced apart between the first manifold and the second manifold; and

[0088] Multiple sets of heat exchange tubes are inserted through different holes in the fins, and the two ends of the heat exchange tubes are connected to the first manifold and the second manifold, respectively.

[0089] The present invention will be further illustrated below through specific embodiments:

[0090] All raw materials used in the embodiments of this invention are commercially available, and this invention does not impose any restrictions on the source of raw materials.

[0091] Example 1

[0092] The fin in Example 1 includes a fin substrate and a hydrophobic coating applied to the surface of the fin substrate; wherein, reference is made to... Figure 1 The fin substrate includes a heat transfer section 20 and a drainage section 10 arranged along the longitudinal direction of the fin substrate. The heat transfer section 20 is provided with pipe holes 201 at intervals along the longitudinal direction of the fin substrate, and the drainage section 10 is provided with drainage grooves 101 at intervals along the longitudinal direction of the fin substrate.

[0093] The drainage ditch extends downwards from the left side of the drainage section to the right side, following a rapid curve. The lateral width of the fin substrate is approximately 40 mm, the lateral projection length of the drainage ditch on the fin substrate is approximately 5 mm, the longitudinal projection length of the drainage ditch on the fin substrate is approximately 3 mm, and the spacing between adjacent drainage ditches is 5 mm. The depth of the drainage ditch is approximately 0.8 mm, and the width of the drainage ditch is approximately 0.8 mm.

[0094] The hydrophobic coating on the fin substrate surface includes a topcoat and a basecoat, wherein the raw materials for the topcoat include:

[0095] Graphene (1μm~3μm): 5wt%; PFOTES: 0.9wt%; dispersant (BYK-163): 0.5wt%; and the balance is bisphenol A type epoxy resin.

[0096] Accordingly, the preparation process of the coating used to prepare the topcoat includes the following steps:

[0097] Mix one-fifth of the epoxy resin and PFOTES and stir for 15 minutes to obtain the modified liquid; mix the graphene, dispersant and the remaining epoxy resin and disperse by high-speed shear (2000 rpm) for 30 minutes, then add the modified liquid and disperse by high-speed shear (2000 rpm) for 30 minutes, and degas under vacuum to complete the preparation.

[0098] The raw materials for the primer coating include:

[0099] Micron-sized alumina (1μm~2μm): 30wt%; dispersant (BYK-163): 1wt%; and the balance being bisphenol A type epoxy resin.

[0100] Accordingly, the preparation process of the coating used to prepare the primer layer includes the following steps:

[0101] The dried micron-sized alumina, dispersant, and bisphenol A epoxy resin were mixed at low speed (200 rpm) for 10 min, and then degassed under vacuum to complete the preparation.

[0102] The method for preparing the fins in Example 1 includes the following steps:

[0103] S1. Provide an aluminum foil, roll it to a thickness of 0.085mm~0.105mm, and cut it to obtain a fin substrate;

[0104] S2. Apply a primer coating to the surface of the prepared fin substrate and cure it at 100°C for 15 minutes to form a base coating; apply a top coating to the surface of the base coating and cure it at 180°C for 30 minutes to form a top coating, thus forming a hydrophobic coating.

[0105] S3. The fin substrate with the hydrophobic coating is stamped and formed, and drainage grooves with corresponding parameters are formed on the surface of the fin substrate to obtain the fin.

[0106] The heat exchanger in Example 1 is obtained by replacing the fins in Example 1 with the heat exchanger fins of the corresponding model of air conditioner in Comparative Example 1.

[0107] Comparative Example 1

[0108] Comparative Example 1 is based on Example 1. Comparative Example 1 is a commercially available air conditioner with model number KFR48GW. The heat exchanger of this air conditioner uses hydrophilic aluminum foil, and the surface of the fins does not have the fastest curve-type drainage groove described in this application.

[0109] Performance testing

[0110] (1) The free low temperature heating capacity (W) and free low temperature heating-defrosting cycle (min) of the heat exchangers in Example 1 and Comparative Example 1 were determined with reference to the standard GB / T 7725-2022 "Room Air Conditioners"; wherein, the indoor operating condition was set to dry bulb temperature 20℃ / wet bulb temperature 15℃, and the outdoor operating condition was set to dry bulb temperature 2℃ / wet bulb temperature 1℃.

[0111] (2) The abrasion resistance of the hydrophobic coating of the fins in Example 1 was determined according to the standard ASTM-D968. The test results are shown in Table 1.

[0112] Table 1

[0113]

[0114] Analysis of the data in Table 1 shows that, compared with heat exchangers and refrigeration equipment with conventional fin structures and surface morphologies, the refrigeration equipment with fins produced in this application has a significantly higher free low-temperature heating capacity, leading by about 10%; the free low-temperature heating-defrosting cycle is also significantly longer, leading by about 70%.

[0115] The hydrophobic coating of the fins prepared in this application showed no significant decrease in hydrophobicity and thermal conductivity after 600 wear cycles under the test conditions corresponding to standard ASTM-D968; thus, the hydrophobic coating of the fins prepared in this application has excellent strength, adhesion and stability.

[0116] In summary, the fins designed in this invention can improve the heat exchange efficiency of the heat exchanger and reduce frost formation, while also extending the service life of the heat exchanger and maintaining its heat exchange efficiency at a high level over a long period of time.

[0117] 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 transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within 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 near the windward side of the fin base; The heat transfer section is provided with pipe holes for passing through heat exchange tubes, and the drainage section is provided with drainage trenches. The drainage ditch extends from one side of the pipe hole to the windward side in a rapid curve shape; The fin also includes a hydrophobic coating applied to the surface of the fin substrate, the hydrophobic coating comprising a base coating and a top coating formed sequentially; The base coating comprises 20wt% to 50wt% micron-sized alumina and the balance being epoxy resin; the top coating comprises 1wt% to 5wt% micron-sized graphene and the balance being epoxy resin. The topcoat includes graphene grafted with perfluorosilane; and / or, the topcoat includes epoxy resin modified with perfluorosilane.

2. The fin as described in claim 1, characterized in that, The drainage section is provided with multiple drainage grooves at intervals along the second direction of the fin substrate, and the second direction intersects with the first direction.

3. The fin as described in claim 1, characterized in that, The drainage ditch extends from one side of the pipe hole to the windward side, and the height of the drainage ditch gradually decreases in the second direction of the fin substrate.

4. The fin as described in claim 1, characterized in that, The drainage groove extends in an arc shape on the surface of the fin substrate.

5. The fin as described in claim 2, characterized in that, The projected length of the drainage groove in the first direction of the fin substrate accounts for 10% to 20% of the length of the fin substrate in the first direction; And / or, the projected length of the drainage groove in the second direction of the fin substrate is 5% to 10% of the length of the fin substrate in the first direction; And / or, the spacing between adjacent drainage grooves is 10% to 25% of the length of the fin substrate in the first direction.

6. The fin as described in claim 1, characterized in that, The depth of the drainage ditch is 0.3mm~1mm; And / or, the width of the drainage ditch is 0.5mm to 2mm.

7. The fin as claimed in claim 1, characterized in that, The heat transfer section is provided with a plurality of tube holes spaced apart along the second direction of the fin substrate for inserting heat exchange tubes.

8. The fin as claimed in claim 1, characterized in that, The thickness of the hydrophobic coating is 1μm~10μm; And / or, the ratio of the thickness of the base coating to the thickness of the top coating is (0.5~4.5):

1.

9. A method for preparing a fin as described in any one of claims 1 to 8, characterized in that, The method for preparing the fins includes the following steps: S1. Provide an aluminum foil, roll and cut it to obtain a fin substrate; S2. Apply a primer to the surface of the substrate to be treated obtained in step S1, and cure it to form a base coating; apply a topcoat to the surface of the base coating, and cure it to form a topcoat, forming a hydrophobic coating. S3. The fin substrate after the hydrophobic coating is formed in step S2 is stamped and formed, and drainage grooves are formed on the surface of the fin substrate to obtain fins.

10. The method for preparing fins as described in claim 9, characterized in that, 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 base coating is 90℃~110℃; And / or, in step S2, the curing temperature of the surface coating is 170℃~190℃.

11. A heat exchanger, characterized in that, The heat exchanger includes: First manifold and second manifold; and Multiple sets of fins, wherein the fins are the fins according to any one of claims 1 to 8, and the fins are spaced apart between the first manifold and the second manifold; and Multiple sets of heat exchange tubes are provided, the heat exchange tubes are inserted through the tube holes of the fins, and the two ends of the heat exchange tubes are respectively connected to the first manifold and the second manifold.

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