External magnetic field heating compound coating cold air machine defrosting device and manufacturing method

Abstract

This invention discloses a defrosting device and manufacturing method for an air cooler with an external magnetic field-heated composite coating, relating to the field of refrigeration technology. The device includes a heat insulation layer coated on the outer surface of the coils and fins of the air cooler; a hydrophobic composite coating coated on the outside of the heat insulation layer, containing nano-magnetic particles for generating heat under the action of an alternating magnetic field; and coils disposed on both sides of the air cooler for generating an alternating magnetic field in the area where the coils and fins are located when energized. This invention discloses a defrosting device for an air cooler with an external magnetic field-heated composite coating, which can significantly delay frost formation, save energy during the defrosting process, and produce very little defrost water residue. It solves the problems of incomplete defrost water drainage, easy secondary frost formation, or ice buildup blocking air ducts in traditional defrosting methods, and achieves zero temperature fluctuations in cold storage.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, and in particular to a defrosting device and manufacturing method for a cold air blower with an external magnetic field heating composite coating. Background Technology

[0002] During long-term operation, the coils and fins of the air coolers in low-temperature warehouses are prone to condensation and frost formation. Frost formation on the coils and fins of the air coolers can not only cause the cooling function to fail, but in severe cases, it can also block the air ducts. Therefore, defrosting must be performed regularly.

[0003] Existing defrosting methods for cold air blowers include electric defrosting and hot air defrosting. The existing defrosting methods have the following problems: electric defrosting is like lighting a fire in the middle of an ice block. Most of the heat is absorbed by the refrigerant inside the pipe, which is extremely power-consuming and can easily damage the fins. The defrosting process is time-consuming, causing large fluctuations in the temperature of the cold storage. Hot air defrosting requires the refrigeration system to be shut down, which causes drastic fluctuations in the storage temperature and seriously affects the preservation of goods.

[0004] Therefore, the industry urgently needs a new defrosting technology that can preserve food without shutting down the machine and is also highly efficient and energy-saving. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by proposing a defrosting device and manufacturing method for a cold air blower with an external magnetic field heating composite coating.

[0006] The technical means employed in this invention are as follows: A defrosting device for a cold air blower with an external magnetic field heating composite coating includes: A heat insulation layer coated on the outer surface of the coil and fins of the air cooler, the thickness of the heat insulation layer is 1~10 micrometers, and the material of the heat insulation layer is nano aerogel or special ceramic. When the air cooler is working normally, the heat insulation layer allows external heat to penetrate the heat insulation layer and exchange heat with the coil and fins. When the air cooler is defrosting, the heat generated by the hydrophobic composite coating is isolated. A hydrophobic composite coating is applied to the outside of the heat insulation layer, and the hydrophobic composite coating contains nano-magnetic particles for generating heat under the action of an alternating magnetic field. Additionally, coils are provided on both sides of the air cooler to generate an alternating magnetic field in the area where the coil and fins are located when energized.

[0007] Furthermore, the thickness of the hydrophobic composite coating is 20-50 micrometers.

[0008] Furthermore, the hydrophobic composite coating is made of a low surface energy resin.

[0009] Furthermore, the nanomagnetic particles are made of nanoferrite particles with a Curie temperature of 2~5℃.

[0010] Furthermore, the coil has multiple sets, which are arranged at different heights on both sides of the air cooler, and the multiple sets of coils are independent windings that can be controlled separately.

[0011] A method for manufacturing a defrosting device for a cold air blower having the external magnetic field heating composite coating described in this application includes the following steps: Step 1: Clean the surface of the coils and fins of the air cooler to remove oil and oxide layers from the outer surface of the coils and fins. Step 2: Spray the insulation slurry onto the outer surface of the coil and fins to form an insulation layer with a thickness of 1 to 10 micrometers on the outer surface of the coil and fins. Step 3: Mix the hydrophobic composite coating and nano-magnetic particles evenly and spray them onto the outer surface of the heat insulation layer to form a hydrophobic composite coating. Step 4: Install coils that can generate alternating magnetic fields on both sides of the air cooler's casing.

[0012] Furthermore, the spraying thickness of the hydrophobic composite coating is 20-50 micrometers; the material of the hydrophobic composite coating is a low surface energy resin; the material of the nanomagnetic particles is nanoferrite particles with a Curie temperature of 2-5℃; and the material of the heat insulation layer slurry is nanoaerogel or special ceramics.

[0013] Furthermore, multiple sets of coils are installed on both sides of the outer casing of the air cooler. The multiple sets of coils are located at different heights on both sides of the air cooler, and the multiple sets of coils are independent windings that can be controlled separately.

[0014] Compared with the prior art, the defrosting device and manufacturing method for air coolers with external magnetic field heating composite coating disclosed in this invention have the following beneficial effects: 1. The superhydrophobic composite coating does not affect cooling and heat exchange and delays frosting time: Specifically, this application has a hydrophobic composite coating on the coil and fins. The hydrophobic composite coating not only does not affect cooling and heat exchange, but also effectively prevents water droplets from sticking and allows them to slide off directly. This delays frosting time from the source and greatly slows down frosting, allowing the air cooler to maintain a high-efficiency heat absorption state for a long time.

[0015] 2. 100% of the heat is used for defrosting, saving energy and electricity: In traditional defrosting, the heat is easily absorbed by the copper coil, resulting in energy waste. However, this invention blocks the heat generated by setting a heat insulation layer. That is, all the heat emitted from the hydrophobic composite coating is used to melt the frost layer and is not transferred to the refrigerant through the copper coil. This results in high energy utilization and energy saving during defrosting.

[0016] 3. Ice layer detaches completely, eliminating ice blockage: After the frost layer melts with heat, the hydrophobic composite coating causes the ice layer to lose its adhesion and slide off completely. Very little defrost water residue is produced, solving the problems of incomplete defrost water drainage, easy re-frost formation, or ice buildup that clogs air ducts, common with traditional methods.

[0017] 4. Defrosting without airflow, achieving minimal or zero temperature fluctuations in cold storage: In this application, the electromagnetic coil is installed outside the air cooler and activated without airflow, eliminating the need to stop the machine for defrosting and achieving minimal or zero temperature fluctuations in the cold storage. Attached Figure Description

[0018] Figure 1 A front view of a cold air blower with an external magnetic field heated composite coating as disclosed in this application; Figure 2 A schematic cross-sectional view of the coil of a cold air blower having the external magnetic field heating composite coating defrosting device disclosed in this application; Figure 3 A view of a cold air blower with a defrosting device for a cold air blower having an external magnetic field heated composite coating as disclosed in this application, taken from the AA direction. In the diagram: 1. Air cooler; 10. Outer casing; 11. Magnetic window; 12. Coil; 13. Fins; 14. Fan; 2. Insulation layer; 3. Hydrophobic composite coating; 4. Nano-magnetic particles; 5. Coil; 6. Frost layer. Detailed Implementation

[0019] like Figure 1 , Figure 2 and Figure 3 As shown, a defrosting device for a cold air blower with an external magnetic field heating composite coating includes: The heat insulation layer 2 is coated on the outer surface of the coil 12 and fins 13 of the air cooler 1; A hydrophobic composite coating 3 is applied to the outside of the heat insulation layer 2, and the hydrophobic composite coating 3 contains nano-magnetic particles 4 for generating heat under the action of an alternating magnetic field. In addition, coils 5 are provided on both sides of the air cooler 1 to generate an alternating magnetic field in the area where the coil 12 and the fins 13 are located when energized.

[0020] Specifically, such as Figure 1 , Figure 2 and Figure 3As shown, the air cooler 1 includes a housing 10, a fan 14, a coil 12, and fins 13. The fins 13 are disposed on the coil 12, which is generally made of copper. The coil 12 is disposed inside the housing 10, which is generally a metal shell structure. The fan 14 is disposed on one side of the housing 10. Refrigerant is introduced into the coil 12. Through the coil 12, fins 13, and fan 14, heat exchange between the outside and the refrigerant in the coil 12 can be achieved. The defrosting device for an air cooler with an external magnetic field heating composite coating disclosed in this application includes a heat insulation layer 2 coated on the outer surface of the coil 12 and fins 13 of the air cooler 1; a hydrophobic composite coating 3 is also coated on the outside of the heat insulation layer 2, and nano-magnetic particles 4 are disposed in the hydrophobic composite coating 3. The nano-magnetic particles 4 can generate heat under the action of an alternating magnetic field; coils 5 are also provided on both sides of the air cooler 1. The coils 5 can be directly installed inside the outer casing 10 of the air cooler 1 or installed on the outside of the outer casing 10 of the air cooler 1. Preferably, the coils 5 are installed on the outside of the outer casing 10 of the air cooler 1, so as not to change the internal structure and layout of the air cooler 1 and to facilitate installation; an alternating current (preferably a medium-high frequency alternating current, such as 20~50KHz) can be passed through the coils 5. After the alternating current is passed through the coils 5, an alternating magnetic field is generated ( Figure 1 (The middle arrow B indicates the direction of magnetic field penetration). The alternating magnetic field interacts with the nano-magnetic particles 4 within the hydrophobic composite coating 3 on the coil 12 and fins 13, generating heat. Since the outer surfaces of the coil 12 and fins 13 are provided with a heat insulation layer 2, the heat generated by the nano-magnetic particles 4 under the action of the alternating magnetic field is first transferred to the frost layer 6 on the hydrophobic composite coating 3. The frost layer 6 absorbs the heat and melts, instantly losing its adhesive force under the action of the hydrophobic composite coating 3, causing the frost layer 6 to slide off or detach from the coil 12 and fins 13 to cool down. In the water collection tray below the fan 1, an antifreeze component is installed at the bottom of the water collection tray and / or on the connected drain pipe. The antifreeze component includes an insulation layer wrapped around the outside of the water collection tray and the drain pipe, and an electric heating tape (or heating wire) laid inside the insulation layer. During the process of heating the coating by an external magnetic field, the electric heating tape is energized and heats up, providing micro-heat compensation for the water collection tray, assisting the rapid and complete melting of the residual solid frost layer, and ensuring that the frost water is smoothly discharged into the drainage system outside the cold storage in liquid form through the drain pipe, thereby completing the final discharge treatment of the defrosting process.

[0021] The defrosting device for air conditioners with external magnetic field heating composite coating disclosed in this invention has the following advantages: 1. The superhydrophobic composite coating does not affect cooling and heat exchange and delays frosting time: Specifically, this application has a hydrophobic composite coating 3 on the coil 12 and fins 13. The hydrophobic composite coating 3 not only does not affect cooling and heat exchange, but also effectively prevents water droplets from sticking and allows them to slide off directly. This delays the frosting time from the source and allows the air cooler to maintain a high-efficiency heat absorption state for a long time.

[0022] 2. 100% of the heat is used for defrosting, saving energy and electricity: In traditional defrosting, the heat is easily absorbed by the copper coil 12, resulting in energy waste. However, this invention blocks the generated heat by setting a heat insulation layer, that is, all the heat emitted from the hydrophobic composite coating is used to melt the frost layer. Figure 2 The arrow D in the middle indicates the direction of heat transfer, which is transferred to the refrigerant without passing through the copper coil 12. Figure 1 The middle arrow C indicates the direction of refrigerant flow, highlighting its high energy efficiency and power-saving defrosting features.

[0023] 3. Ice layer detaches completely, eliminating ice blockage: After the frost layer melts with heat, the hydrophobic composite coating 3 causes the ice layer to lose its adhesion and slide off completely into the water collection tray. Very little defrost water residue is produced, solving the problems of incomplete defrost water drainage, easy re-frost formation, or ice buildup that clogs air ducts in traditional systems.

[0024] 4. Defrosting without airflow, resulting in minimal temperature fluctuations in cold storage: In this application, the electromagnetic coil is installed outside the air cooler and activated without airflow, eliminating the need to stop the machine for defrosting and achieving minimal or no temperature fluctuations in the cold storage.

[0025] Furthermore, the thickness of the heat insulation layer 2 is 1 to 10 micrometers.

[0026] Specifically, in this embodiment, the thickness of the insulation layer 2 is 1-10 micrometers. It can effectively block the heat generated by the nano-magnetic particles 4 in the hydrophobic composite coating 3 under the action of an alternating magnetic field from being transferred to the refrigerant in the coil 12 and fins 13 of the air cooler 1. At the same time, it can ensure that when the air cooler 1 is working normally, the external heat can pass smoothly through the insulation layer 2 and interact with the refrigerant in the coil 12 and fins 13 of the air cooler 1, thereby ensuring the cooling efficiency of the air cooler 1. That is, when the air cooler 1 is working normally, because the insulation layer 2 is relatively thin, the external heat can easily penetrate the insulation layer 2 and be transferred to the refrigerant in the coil 12 and fins 13 to achieve cold storage cooling. When defrosting (the alternating magnetic field is introduced into the coil 5, and the heat generated by the nano-magnetic particles 4 in the hydrophobic composite coating 3 under the action of the alternating magnetic field), due to the setting of the insulation layer 2, the heat is preferentially conducted to the frost layer 6, and the frost layer 6 absorbs the heat and melts.

[0027] Furthermore, the heat insulation layer 2 is made of nano-aerogel or special ceramics.

[0028] Specifically, in this embodiment, the insulation layer 2 is made of nano-aerogel or special ceramics. It effectively blocks the heat generated by the nano-magnetic particles 4 in the hydrophobic composite coating 3 under the action of an alternating magnetic field from being transferred to the refrigerant in the coil 12 and fins 13 of the air cooler 1. Simultaneously, it ensures that when the air cooler 1 is operating normally, external heat can smoothly pass through the insulation layer 2 and interact with the refrigerant in the coil 12 and fins 13, thereby ensuring the cooling efficiency of the air cooler 1. In other words, the insulation layer 2, made of micron-sized nano-aerogel or special ceramics, is extremely thin, with negligible thermal resistance, and will not hinder the air cooler 1 from normally absorbing heat from the cold storage.

[0029] Furthermore, the thickness of the hydrophobic composite coating 3 is 20-50 micrometers.

[0030] Specifically, in this embodiment, the thickness of the hydrophobic composite coating 3 is 20-50 micrometers. This thickness ensures that the nano-magnetic particles 4 in the hydrophobic composite coating 3 generate enough heat under the action of an alternating magnetic field for rapid defrosting. At the same time, it also allows the heat to pass smoothly through the hydrophobic composite coating 3 and interact with the coil 12 and fins 13 of the air cooler 1, thereby ensuring the cooling efficiency of the air cooler 1.

[0031] Furthermore, the hydrophobic composite coating 3 is made of a low surface energy resin.

[0032] Specifically, in this embodiment, the hydrophobic composite coating 3 is made of a low surface energy resin (e.g., fluorocarbon resin). The low surface energy resin has super hydrophobic properties, which makes it difficult for condensate in the air cooler 1 to stick to the coil 12 or fins 13, thereby delaying the frosting time from the source and allowing the air cooler 1 to maintain a high-efficiency heat absorption state for a long time.

[0033] Furthermore, the nanomagnetic particles 4 are made of nanoferrite particles with a Curie temperature of 2~5℃.

[0034] Specifically, in this embodiment, the nano-magnetic particles 4 are made of nano-ferrite particles with a Curie temperature of 2~5℃. They can not only generate heat quickly under the action of an alternating magnetic field for defrosting, but also automatically lose their magnetism and stop heating when the temperature reaches 2~5℃, preventing dry burning and damage to the equipment.

[0035] Furthermore, the coil 5 has multiple sets, which are arranged at different heights on both sides of the air cooler 1, and the multiple sets of coil 5 are independent windings that can be controlled separately.

[0036] Specifically, the coil 5 has multiple sets, each with an independent winding structure and connected to a controller. The controller can control each set of coil 5 to work independently, meaning it can individually control the flow of medium-high frequency (e.g., 20~50KHz) alternating current into each set of coil 5. This generates an alternating magnetic field in different sets of coil 5. The alternating magnetic field passes through the magnetic window 11 on the outer casing 10 of the air cooler 1 and interacts with the nano-magnetic particles 4 on the coil 12 and fins 13 in a specific area (corresponding to the energized coil 5). Due to the alternating magnetic field, the nano-magnetic particles 4 begin to generate intense friction and heat, thereby defrosting the frost layer 6 in that area. By setting multiple sets of coil 5, different sets of coil 5 can be energized according to the defrosting location, which not only further achieves energy saving but also avoids heating unfrosted areas, thus preventing any impact on the performance and lifespan of the air cooler 1. In this embodiment, the coil 5 has three sets, which are installed on both sides of the outer casing 10 of the air cooler 1, in an upper, middle and lower configuration, to defrost the coils 12 and fins 13 in the upper, middle and lower parts of the air cooler 1, respectively. In this embodiment, capacitive frost thickness sensors (which identify the frost thickness by the change of dielectric constant) are installed on the metal surfaces of the coils 12 or fins 13 in the upper, middle and lower parts of the air cooler 1, where frost is most likely to form and where the wind can blow directly. When the frost thickness in a certain area exceeds a preset threshold (e.g., 0.8~1.5mm), the controller determines that the area needs to be defrosted and triggers the coil 5 at the corresponding position to be energized.

[0037] A method for manufacturing a defrosting device for a cold air blower having the external magnetic field heating composite coating described in this application includes the following steps: Step 1: Clean the surface of the coil 12 and fins 13 of the air cooler 1 to remove oil and oxide layer from the outer surface of the coil 12 and fins 13. Specifically, a weak acid or a special cleaning agent is used to thoroughly clean the oil and oxide layer on the surface of the coil 12 (usually a copper coil) and fins 13 (usually aluminum fins) of the air cooler 1, so that the subsequent coating can firmly adhere to the outer surface of the coil 12 and fins 13. Step 2: Spray the insulation layer slurry onto the outer surface of the coil 12 and fins 13, so that an insulation layer 2 with a thickness of 1~10 micrometers is formed on the outer surface of the coil 12 and fins 13. Specifically, nano-aerogel or special ceramic dispersion is selected as the insulation layer slurry and sprayed evenly onto the outer surface of coil 12 and fin 13 with a spray gun. The thickness is strictly controlled to be 1~10 micrometers, thereby forming an insulation layer 2 with a thickness of 1~10 micrometers on the outer surface of coil 12 and fin 13. The function of the insulation layer 2 is that when the air cooler 1 is working normally, the heat of the cold storage can easily penetrate the insulation layer 2 and be transferred to the refrigerant in coil 12 to achieve cold storage cooling. During defrosting, the insulation layer 2 can block the heat emitted from the hydrophobic composite coating 3 to the outside, preventing heat transfer between the heat and the refrigerant in coil 12. Step 3: Mix the hydrophobic composite coating and nano-magnetic particles 4 evenly and spray them onto the outer surface of the heat insulation layer 2 to form a hydrophobic composite coating 3; Specifically, in this embodiment, the hydrophobic composite coating is made of a low surface energy resin (e.g., fluorocarbon resin), and the nano-magnetic particles are made of nano-ferrite particles with a Curie temperature of 2-5°C. The nano-ferrite particles with a Curie temperature of 2-5°C are uniformly mixed with the low surface energy resin (e.g., fluorocarbon resin), and then the mixed solution is uniformly sprayed onto the outer surface of the heat insulation layer 2. The spraying thickness is controlled at 20-50 micrometers, and then dried and cured at low temperature to form a hydrophobic composite coating 3. Step 4: Install coils 5 that can generate alternating magnetic fields on both sides of the outer casing 10 of the air cooler 1; Specifically, multiple elongated windows are machined on both sides of the outer casing 10 of the evaporator 1, corresponding to the positions of the internal evaporator section (which consists of coils 12 and fins 13). These elongated windows are then sealed with low-temperature resistant fiberglass or engineering plastic to form magnetically permeable windows 11. This allows the alternating magnetic field to pass through the magnetically permeable windows 11 without loss and enter the interior of the evaporator 1, without affecting the sealing performance of the outer casing 10. On the outside of the magnetically permeable windows 11, flat pure copper induction coils 5 are attached. The coils 5 are divided into multiple groups (e.g., upper, middle, and lower groups) of independent windings along the height direction of the evaporator, and are connected to the control board respectively to achieve zoned control.

[0038] The working process of the air cooler with the external magnetic field heating composite coating defrosting device disclosed in this application is as follows: Daily cooling: In normal cooling mode, the air cooler 1 operates normally. When the humid air in the cold storage comes into contact with the hydrophobic composite coating 3 on the coils 12 and fins 13, the water droplets do not adhere to the surface of the coils 12 and fins 12, but instead slide directly into the drip tray, delaying the frosting time. Simultaneously, although the coils 12 and fins 13 are equipped with a heat insulation layer 2, because the thickness of the heat insulation layer 2 is on the micrometer scale, the temperature difference of approximately 7°C between the air and the refrigerant is sufficient to allow heat to pass smoothly through the heat insulation layer 2 and be transferred to the coils 12 and fins 13 without affecting the cooling efficiency.

[0039] Defrosting mode: When the sensor detects that the frost layer in a certain area (such as the lower part of the windward side) is too thick (the capacitive frost thickness sensor identifies the frost thickness by the change of dielectric constant; when the frost thickness in a certain area exceeds the preset threshold (such as 0.8~1.5mm), the controller determines that the area needs to be defrosted and triggers the corresponding coil 5 to be energized), the controller controls the flow of a medium-high frequency (such as 20~50kHz) alternating current into the corresponding coil 5; the coil 5 generates an alternating magnetic field, which passes through the magnetic window 11 and interacts with the ferrite particles in the hydrophobic composite coating 3. The particles begin to generate heat through intense friction. Since the heat insulation layer 2 is provided, it blocks the heat transfer to the coil 12 and fins 13. The heat is transferred to the frost layer 6 outside the coil 12 and fins 13. The frost layer 6 melts and absorbs a large amount of heat (latent heat of phase change), using all the heat emitted by the hydrophobic composite coating 3 to melt the frost layer.

[0040] After the frost layer melts, it instantly loses its adhesive force and slides off under the action of the hydrophobic composite coating 3, leaving no defrosting water residue. As the frost layer falls off, the temperature of the hydrophobic composite coating 3 rises. When it reaches the Curie point (2~5℃), the ferrite particles automatically lose their magnetism and stop heating, preventing dry burning and damage to the equipment. When the frost thickness collected by the capacitive frost thickness sensor in a certain area is lower than the stop threshold (e.g., 0.8mm), the controller determines that defrosting in that area has ended and triggers the corresponding coil 5 to cut off power.

[0041] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A defrosting device for a cold air blower with an external magnetic field heating composite coating, characterized in that, include: A heat insulation layer coated on the outer surface of the coil and fins of the air cooler, the thickness of the heat insulation layer is 1~10 micrometers, and the material of the heat insulation layer is nano aerogel or special ceramic. When the air cooler is working normally, the heat insulation layer allows external heat to penetrate the heat insulation layer and exchange heat with the coil and fins. When the air cooler is defrosting, the heat generated by the hydrophobic composite coating is isolated. A hydrophobic composite coating is applied to the outside of the heat insulation layer, and the hydrophobic composite coating contains nano-magnetic particles for generating heat under the action of an alternating magnetic field. Additionally, coils are provided on both sides of the air cooler to generate an alternating magnetic field in the area where the coil and fins are located when energized.

2. The defrosting device for a cold air blower with an external magnetic field heating composite coating according to claim 1, characterized in that: The thickness of the hydrophobic composite coating is 20-50 micrometers.

3. The defrosting device for a cold air blower with an external magnetic field heating composite coating according to claim 2, characterized in that: The hydrophobic composite coating is made of a low surface energy resin.

4. The defrosting device for a cold air blower with an external magnetic field heating composite coating according to claim 3, characterized in that: The nanomagnetic particles are made of nanoferrite particles with a Curie temperature of 2~5℃.

5. The defrosting device for a cold air blower with an external magnetic field heating composite coating according to claim 1, characterized in that: The coil has multiple sets, which are arranged at different heights on both sides of the air cooler, and each set of coils is an independent winding and can be controlled separately.

6. A method for manufacturing a defrosting device for a cold air blower having an external magnetic field heated composite coating as described in any one of claims 1 to 5, characterized in that, Includes the following steps: Step 1: Clean the surface of the coils and fins of the air cooler to remove oil and oxide layers from the outer surface of the coils and fins. Step 2: Spray the insulation slurry onto the outer surface of the coil and fins to form an insulation layer with a thickness of 1 to 10 micrometers on the outer surface of the coil and fins. Step 3: Mix the hydrophobic composite coating and nano-magnetic particles evenly and spray them onto the outer surface of the heat insulation layer to form a hydrophobic composite coating. Step 4: Install coils that can generate alternating magnetic fields on both sides of the air cooler's casing.

7. The manufacturing method of the defrosting device for a cold air blower with an external magnetic field heated composite coating according to claim 6, characterized in that: The hydrophobic composite coating has a spray thickness of 20-50 micrometers; the hydrophobic composite coating is made of low surface energy resin; the nanomagnetic particles are made of nanoferrite particles with a Curie temperature of 2-5℃; and the heat insulation layer slurry is made of nanoaerogel or special ceramics.

8. The manufacturing method of the defrosting device for a cold air blower with an external magnetic field heated composite coating according to claim 7, characterized in that: Multiple sets of coils are installed on both sides of the outer casing of the air cooler. The multiple sets of coils are located at different heights on both sides of the air cooler, and the multiple sets of coils are independent windings that can be controlled separately.

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