A method for deicing fan blades using microwave radiation

Abstract

The present invention relates to the field of wind power generation, and in particular to a method for microwave radiation de-icing of wind turbine blades. The present invention realizes microwave de-icing technology for wind turbine blades. The super-hydrophobic silicon carbide / polyurethane composite coating ensures the hydrophobic performance of the blade surface, the modification of the power supply line ensures the self-power supply of the microwave heating system, the design of the microwave heating system and the arrangement of the radiation antenna realize the directional radiation of microwave energy, and the silicon carbide / graphite / polyurethane composite absorbing coating absorbs microwave energy and converts it into heat energy, thereby realizing efficient de-icing of the blades. The present invention has low energy consumption. Compared with traditional de-icing methods, the present invention adopts a microwave heating source with lower energy consumption. High efficiency: Microwave energy can quickly melt ice and snow on the surface of the blade, prevent the formation of new ice and snow, and improve the efficiency of wind energy conversion. Flexible adaptability: The present invention is suitable for wind turbine blades of different lengths and shapes. By optimizing the number and placement of radiation antennas, it has high flexibility and adaptability.

Description

Technical Field

[0001] The present invention relates to the field of wind power generation, and in particular to a method for deicing fan blades using microwave radiation. Background Art

[0002] Wind energy, as a clean and renewable energy source, has been widely used and developed. However, in cold climates, wind turbine blades are susceptible to icing, leading to reduced wind energy conversion efficiency, unstable operation, and increased risk of equipment damage. Therefore, to improve the reliability and economic efficiency of wind farms, wind turbine blade de-icing technology has become a focus of research and attention.

[0003] Currently, common wind turbine blade de-icing methods include mechanical de-icing, thermal de-icing, and chemical de-icing. However, traditional mechanical de-icing requires additional equipment and manual operation, resulting in high costs and low efficiency. Thermal de-icing methods primarily use electrical heating or heating media, but these methods suffer from high energy consumption and complex operation. Chemical de-icing requires the use of chemicals, which can pollute the environment.

[0004] To overcome the limitations of traditional de-icing methods, microwave radiation de-icing technology has emerged. Microwave radiation de-icing uses microwave energy to heat the blade surface. This energy is absorbed by the blades, rapidly melting ice and snow and preventing new ice and snow from forming. Compared to traditional methods, microwave radiation de-icing offers advantages such as low energy consumption, high efficiency, and environmental friendliness.

[0005] However, existing microwave radiation deicing technology still faces several challenges. Among them, the rational layout of microwave heating sources, the design of effective radiation antennas, and the control of microwave power are among the issues that need to be addressed urgently. Therefore, the present invention provides a system and method for microwave radiation deicing of wind turbine blades. By rationally designing the microwave heating source and antenna, it achieves efficient and low-energy deicing of wind turbine blades. Summary of the Invention

[0006] In order to solve the above problems, the present invention provides a microwave deicing method applied to wind turbine blades.

[0007] The technical solutions of the present invention are as follows:

[0008] A method for deicing fan blades by microwave radiation, comprising the following steps:

[0009] The first step is to prepare silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating

[0010] Using polyurethane as the main paint and silicon carbide or graphite as the absorbing filler, a high-efficiency absorbing coating suitable for deicing the surface of wind turbine blades is prepared.

[0011] (1) Preparation of silicon carbide / polyurethane composite absorbing coating

[0012] Silicon carbide was selected as the absorbing filler, and silicon carbide powder was added to the polyurethane coating as the absorbing filler to prepare silicon carbide / polyurethane composite coatings with different morphologies; silicon carbide was mixed with polyurethane to prepare silicon carbide / polyurethane composite coatings with different loadings.

[0013] (2) Preparation of graphite / polyurethane composite absorbing coating

[0014] First, the redox method was used to regulate the microscopic defects and oxygen-containing functional groups on the graphite surface, and graphite with different oxidation degrees was added to the polyurethane coating by a physical blending method to prepare graphite / polyurethane composite coatings with different oxidation degrees; graphite with different flake thicknesses was prepared by a hydrothermal method / ultrasonic cleaning method, and then added to the polyurethane coating to prepare a graphite / polyurethane composite absorbing coating.

[0015] The second step is to prepare super hydrophobic silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating.

[0016] (1) Preparation of super-hydrophobic silicon carbide / polyurethane composite absorbing coating

[0017] Silicon carbide particles are chemically grafted and modified by a hydrothermal method to allow hydrophobic groups to exist on the surface of the silicon carbide; the modified filler is mixed with the resin by a physical blending method, and then the coating is sprayed on the surface of the blade.

[0018] (2) Preparation of super-hydrophobic graphite / polyurethane composite absorbing coating

[0019] First, graphite oxide / graphene oxide nanosheets were synthesized using a modified Hummers method. Then, alkyl chains were grafted onto the nanosheets via an amidation reaction to create superhydrophobic nanosheets. The degree of modification was achieved by controlling the reaction time. The coating was then applied to the blade surface by spray coating.

[0020] The third step is to design a microwave de-icing system, which includes modifying the power supply line, designing a microwave heating system, and arranging the radiation antenna:

[0021] 3.1 Modify the power supply circuit to supply the microwave heating system: Based on the total power of the installed microwave source, expand the wind turbine's own power supply system and adjust the box-type transformer, tower base cabinet, and main control cabinet as needed. Add conductive slip rings and brushes, one side of which contacts the conductive slip ring and the other side is electrically connected to the microwave generator in the corresponding blade. This completes the microwave power supply circuit modification.

[0022] 3.2 Microwave heating system design: n (n>=1) adjustable high-power microwave sources are configured. The energy of the high-power microwave source is input into the power distributor after waveguide coaxial conversion and is evenly distributed to each RF switch input end. Then, the antenna operation is realized by controlling the switch on and off.

[0023] 3.3 Radiating antenna arrangement: m (m>=1) adjustable high-power antennas are derived from n microwave sources, and different antenna spacings and placement positions are set to achieve directional radiation of microwaves.

[0024] The fourth step is composite coating application: First, apply the prepared super-hydrophobic silicon carbide / polyurethane composite coating to the ice-prone areas of the blade surface to ensure hydrophobicity. Then, apply the prepared silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating to enhance microwave energy absorption and heat conduction, achieving rapid de-icing. The coating area should match the directional radiation area of ​​the antenna.

[0025] Step 5: Microwave deicing operation:

[0026] 5.1 When de-icing is required, start the microwave source and set the appropriate power and radiation time. Set the power of each microwave source and adjust the radiation time according to actual needs.

[0027] 5.2 The microwave energy generated by the microwave source is radiated directionally to the composite coating coating area via the antenna.

[0028] 5.3 Silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating absorbs microwave energy and converts it into heat energy.

[0029] 5.4 Heat is conducted within the composite material, raising the surface temperature of the blade, thereby rapidly melting and removing ice.

[0030] 5.5 After de-icing is completed, stop the operation of the microwave source and resume normal wind power generation operation.

[0031] Furthermore, the specific operations of step 4 are as follows:

[0032] 4.1 Apply the prepared super-hydrophobic silicon carbide / polyurethane composite coating to the critical ice-forming area on the blade surface, i.e., the 2 / 3 of the blade near the tip, with a thicker coating at the tip. The coating area should match the directional radiation area of ​​the antenna.

[0033] 4.2 Apply the prepared silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating to the spraying area in step 4.1.

[0034] 4.3 Ensure that the paint covers the blade surface evenly during the coating process and avoid dripping or wrinkling of the paint as much as possible.

[0035] Furthermore, the radiating antennas are arranged at the blade root and at the 40% position of the blade, and are led out through high-power cables to receive and transmit microwave energy in a directionally controlled manner.

[0036] This invention implements microwave de-icing technology for wind turbine blades. A super-hydrophobic silicon carbide / polyurethane composite coating ensures the blade surface's hydrophobicity. Modification of the power supply circuit ensures self-powering of the microwave heating system. The design of the microwave heating system and the arrangement of the radiating antennas ensure directional radiation of microwave energy. The silicon carbide / graphite / polyurethane composite absorbing coating absorbs microwave energy and converts it into heat, achieving efficient blade de-icing.

[0037] The advantages of the present invention include but are not limited to:

[0038] 1. Low energy consumption: Compared with traditional deicing methods, the present invention uses a microwave heating source, which consumes less energy.

[0039] 2. High efficiency: Microwave energy can quickly melt the ice and snow on the surface of the blades, prevent the formation of new ice and snow, and improve the efficiency of wind energy conversion.

[0040] 3. Flexible adaptability: The present invention is applicable to wind turbine blades of different lengths and shapes. By optimizing the number and placement of radiating antennas, it has high flexibility and adaptability.

[0041] 4. Safe and reliable: By controlling the microwave power and heating time, the surface temperature of the blades is ensured to be within a reasonable range, avoiding overheating and damage, and ensuring the safe operation of wind turbine blades. BRIEF DESCRIPTION OF THE DRAWINGS

[0042] Figure 1 This is a schematic diagram of the process of microwave de-icing of wind turbine blades;

[0043] Figure 2 This is a schematic diagram of the microwave power supply line transformation;

[0044] Figure 3 is a schematic diagram of a microwave heating system;

[0045] Figure 4 It is a schematic diagram of the radiating antenna arrangement. DETAILED DESCRIPTION

[0046] In order to make the purpose, technology and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and examples.

[0047] Taking a 40m long wind turbine blade as an example, the following is the specific implementation process:

[0048] 1. Preparation of silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating

[0049] (1) Preparation of silicon carbide / polyurethane composite absorbing coating

[0050] Silicon carbide with particle sizes of 200 nm, 1 μm, 10 μm, 50 μm, and 100 μm was selected as an absorbing filler. Silicon carbide powder was added to a polyurethane coating to prepare silicon carbide / polyurethane composite coatings with different morphologies. 10 g of polyurethane was placed in a glass bottle and 0.25 g, 0.5 g, 1 g, 1.5 g, 2 g, 3 g, 3.5 g, 4 g, and 5 g of silicon carbide were weighed and mixed with the polyurethane to prepare silicon carbide / polyurethane composite coatings with different loadings. The prepared silicon carbide / polyurethane composite coatings were applied to the substrate by brushing or spraying. After the coating dried, further brushing was performed to prepare samples with thicknesses of 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, and 5 mm.

[0051] (2) Preparation of graphite / polyurethane composite absorbing coating

[0052] First, the redox method was used to regulate the microscopic defects and oxygen-containing functional groups on the graphite surface, and graphite / graphene with different oxidation degrees was added to the polyurethane coating by a physical blending method to prepare graphite / polyurethane composite coatings with different oxidation degrees; graphite / graphene with different flake thicknesses was prepared by a hydrothermal method / ultrasonic cleaning method, and added to the polyurethane coating to prepare a graphite / graphene / polyurethane composite absorbing coating; the prepared graphite / polyurethane composite coating was applied to the substrate by brushing or spraying, and the coating was continued to be brushed after drying to prepare 0.2mm, 0.5mm, 1mm, 2mm, 3mm and 5mm thick samples respectively.

[0053] 2. Preparation of super-hydrophobic silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating

[0054] (1) Preparation of super-hydrophobic silicon carbide / polyurethane composite absorbing coating

[0055] Silicon carbide particles were chemically grafted and modified using a hydrothermal method to create hydrophobic groups on the surface of the silicon carbide. The modified filler was then mixed with a resin using a physical blending method. The coating was then sprayed onto the blade surface to create samples with thicknesses of 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, and 5 mm.

[0056] (2) Preparation of super-hydrophobic graphite / graphene / polyurethane composite absorbing coating

[0057] Graphite oxide / graphene oxide nanosheets were synthesized using a modified Hummers method. Graphite oxide / graphene oxide nanosheets were then modified by grafting alkyl chains onto the nanosheet surfaces via an amidation reaction to prepare superhydrophobic nanosheets. The degree of modification was achieved by controlling the reaction time. The chemical structure, chemical properties, elemental content, and micromorphology of the graphite / graphene nanosheets with varying degrees of modification were characterized and evaluated. The coating was sprayed onto the blade surface to produce samples with thicknesses of 0.2 mm, 0.5 mm, 1 mm, 2 mm, 3 mm, and 5 mm.

[0058] 3. Design of microwave de-icing system

[0059] 3.1 Transform the power supply line to supply power to the microwave source: adjust the box-type transformer, tower base cabinet and main control cabinet, etc., connect the 690V output to the grid through the box-type transformer, and complete the power supply transformation; add a conductive slip ring, connect it to the nacelle of the wind turbine, fix it so that it does not rotate, and its central axis coincides with the central axis of the hub of the wind turbine; add brushes, fix them on the hub at intervals, correspond to the blades one by one, and rotate with the wind turbine blades and hub; one side of the brush contacts the conductive slip ring, and the other side is electrically connected to the microwave generator in the corresponding blade. Figure 2 shown.

[0060] 3.2 Microwave heating system design: Configure three high-power microwave sources with a frequency of 2.5GHz. The energy of the high-power microwave source is converted by waveguide coaxially and then input into the power distributor. It is evenly distributed to each RF switch input end, and then the antenna is operated by controlling the switch on and off. Figure 3 shown.

[0061] 3.3 Six high-power radiating antennas are arranged in the blade cavity. By observing the ice area of ​​the blade, it can be seen that the windward side is more prone to ice formation, while the leeward side is slightly iced. According to the ice area of ​​the blade, the location of the radiating antenna can be determined: at the root of the blade and at the 40% position of the blade. The microwave energy is received and transmitted directionally through a high-power cable. Figure 4 shown.

[0062] 4. Composite coating application

[0063] 4.1 Apply the prepared super-hydrophobic silicon carbide / polyurethane composite coating to the critical ice-forming area on the blade surface, i.e., the 2 / 3 of the blade near the tip, with a thicker coating at the tip. The coating area should match the directional radiation area of ​​the antenna.

[0064] 4.2 Apply the prepared silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating to the spraying area in step 4.1.

[0065] 4.3 Ensure that the paint covers the blade surface evenly during the coating process and avoid dripping or wrinkling of the paint as much as possible.

[0066] 5. Microwave de-icing operation

[0067] 5.1 When de-icing is required, start the microwave source and set the appropriate power and radiation time. Depending on the specific situation, the power of each microwave source can be set to 6kW, and the radiation time can be adjusted according to actual needs.

[0068] 5.2 The microwave energy generated by the microwave source is radiated directionally to the composite coating coating area via the antenna.

[0069] 5.3 Silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating absorbs microwave energy and converts it into heat energy.

[0070] 5.4 Heat is conducted within the composite material, raising the surface temperature of the blade, thereby rapidly melting and removing ice.

[0071] 5.5 After de-icing is completed, stop the operation of the microwave source and resume normal wind power generation operation.

[0072] The microwave deicing method for wind turbine blades disclosed herein can be widely applied in wind farms, effectively solving the problem of wind turbine blade icing in cold climates. By modifying the power supply circuit, the microwave heating system can be self-powered. By rationally arranging the microwave heating system and radiating antenna within the blade cavity, microwave energy can fully cover the blade surface, achieving comprehensive anti-icing and deicing effects. Furthermore, by controlling the microwave power and adjusting the heating time, the blade surface temperature can be maintained within a safe range, preventing overheating and damage.

Claims

1. A method for deicing fan blades by microwave radiation, characterized in that: Here are the steps: The first step is to prepare silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating Using polyurethane as the main paint and silicon carbide or graphite as the absorbing filler, a high-efficiency absorbing coating suitable for deicing the surface of wind turbine blades is prepared; (1) Preparation of silicon carbide / polyurethane composite absorbing coating Silicon carbide was selected as the absorbing filler, and silicon carbide powder was added to the polyurethane coating as the absorbing filler to prepare silicon carbide / polyurethane composite coatings with different morphologies; silicon carbide was mixed with polyurethane to prepare silicon carbide / polyurethane composite coatings with different loadings; (2) Preparation of graphite / polyurethane composite absorbing coating First, the microscopic defects and oxygen-containing functional groups on the graphite surface were regulated by redox method. Then, graphite with different oxidation degrees was added to polyurethane coating by physical blending method to prepare graphite / polyurethane composite coatings with different oxidation degrees. Graphite with different flake diameters and thicknesses was prepared by hydrothermal method / ultrasonic cleaning method, and then added to polyurethane coating to prepare graphite / polyurethane composite absorbing coatings. The second step is to prepare super hydrophobic silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating. (1) Preparation of super-hydrophobic silicon carbide / polyurethane composite absorbing coating The silicon carbide particles are chemically grafted and modified by a hydrothermal method to allow hydrophobic groups to appear on the surface of the silicon carbide. The modified filler is mixed with the resin by a physical blending method, and then the coating is sprayed on the blade surface. (2) Preparation of super-hydrophobic graphite / polyurethane composite absorbing coating First, graphite oxide / graphene oxide nanosheets were synthesized using a modified Hummers method. Then, alkyl chains were grafted onto the nanosheet surface via an amidation reaction to prepare superhydrophobic nanosheets. Different degrees of modification were achieved by controlling the reaction time. The coating was then sprayed onto the blade surface. The third step is to design a microwave de-icing system, which includes modifying the power supply line, designing a microwave heating system, and arranging the radiation antenna: 3.1 Modify the power supply line to supply power to the microwave heating system: According to the total power of the microwave source to be installed, expand the wind turbine's self-power supply system, adjust the box-type transformer, tower base cabinet and main control cabinet as needed; add conductive slip rings and brushes, one side of the brush contacts the conductive slip ring, and the other side is electrically connected to the microwave generator in the corresponding blade; 3.2 Microwave Heating System Design: n (n>=1) adjustable high-power microwave sources are configured. The energy of the high-power microwave sources is converted through waveguide coaxial transmission and then input into a power divider, where it is evenly distributed to each RF switch input. The antenna is then operated by controlling the switches to turn them on and off. 3.3 Radiating antenna arrangement: m (m>=1) adjustable high-power antennas are derived from n microwave sources, and different antenna spacings and placement positions are set to achieve directional microwave radiation; The fourth step is composite coating application: First, apply the prepared super-hydrophobic silicon carbide / polyurethane composite absorbing coating to the ice-prone areas of the blade surface to ensure the hydrophobic properties of the blade surface. Then, apply the prepared silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating to enhance microwave energy absorption and heat conduction, achieving a rapid deicing effect. The coating area should match the directional radiation area of ​​the antenna radiation. Step 5: Start the microwave de-icing operation.

2. The method for deicing fan blades by microwave radiation according to claim 1, characterized in that: The specific operations of the fourth step are as follows: 4.1 Apply the prepared super-hydrophobic silicon carbide / polyurethane composite absorbing coating to the key ice-forming area on the blade surface, that is, the 2 / 3 position near the blade tip, with a thick coating at the tip of the blade. The coating area should match the directional radiation area of ​​the antenna. 4.2 Apply the prepared silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating to the area sprayed in step 4.1; 4.3 Ensure that the paint covers the blade surface evenly during the coating process and avoid dripping or wrinkling of the paint as much as possible.

3. A method for deicing fan blades by microwave radiation according to claim 1 or 2, characterized in that: In the step 3.3, the radiating antenna is arranged at the blade root and the 40% position of the blade, is led out through a high-power cable, and receives and directionally transmits microwave energy.

4. A method for deicing fan blades by microwave radiation according to claim 1 or 2, characterized in that: The specific operations of the fifth step are as follows: 5.1 When de-icing is required, start the microwave source and set the appropriate power and radiation time; set the power of each microwave source and adjust the radiation time according to actual needs; 5.2 The microwave energy generated by the microwave source is radiated directionally to the composite coating coating area via the antenna; 5.3 Silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating absorbs microwave energy and converts it into heat energy; 5.4 Heat is conducted within the composite material, raising the surface temperature of the blade, thereby rapidly melting and removing ice; 5.5 After de-icing is completed, stop the operation of the microwave source and resume normal wind power generation operation.

5. The method for deicing fan blades by microwave radiation according to claim 3, characterized in that: The specific operations of the fifth step are as follows: 5.1 When de-icing is required, start the microwave source and set the appropriate power and radiation time; set the power of each microwave source and adjust the radiation time according to actual needs; 5.2 The microwave energy generated by the microwave source is radiated directionally to the composite coating coating area via the antenna; 5.3 Silicon carbide / polyurethane composite absorbing coating or graphite / polyurethane composite absorbing coating absorbs microwave energy and converts it into heat energy; 5.4 Heat is conducted within the composite material, raising the surface temperature of the blade, thereby rapidly melting and removing ice; 5.5 After de-icing is completed, stop the operation of the microwave source and resume normal wind power generation operation.

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