Anti-freezing wind power generation blade based on phase change material

Abstract

An anti-freezing wind power generation blade based on phase change materials comprises a multi-layer stacked structure from the leeward side to the windward side, double PCM phase change material layers are arranged, a transition heat conduction layer is arranged between the double PCM phase change material layers, the transition heat conduction layer comprises a porous structure with the aperture ratio gradually changed, and meanwhile heat preservation layers are arranged between the PCM material layers and an outer layer. Through the design of a multi-layer stacked structure, the effects of partitioned anti-freezing and partitioned unfreezing are achieved, and the effect of improving the working safety of the blade under the cold condition is achieved.

Description

Technical Field

[0001] The present invention belongs to the field of wind power generation, and in particular relates to a wind power generation blade designed based on phase change materials to achieve antifreeze. Background Art

[0002] Blade icing has become a persistent problem for wind turbines operating in low-temperature, high-humidity environments (such as high-altitude mountainous areas and coastal wind farms). According to a 2024 report from the International Energy Agency (IEA), over 35% of wind farms worldwide experience an average annual icing duration of more than 500 hours, resulting in a 15-20% loss of power generation and direct economic losses exceeding US$1.7 billion. Traditional anti-icing technology has three major bottlenecks:

[0003] Active anti-icing solutions are energy-inefficient: Electric thermal anti-icing systems consume turbine power, increasing de-icing energy consumption in -10°C environments, significantly reducing wind farm profitability. Hot gas de-icing technology relies on complex piping to transfer waste heat from the generator to the blades, adding weight, degrading aerodynamic performance, and delaying thermal response.

[0004] Passive anti-icing solutions lack sustainability: Current phase change material (PCM) anti-icing technology has fundamental flaws. The phase change temperature of a single-layer PCM architecture is fixed (usually set at 0±0.5°C), which cannot adapt to the drastic temperature difference between day and night. Under typical operating conditions in northern winter (5°C during the day / -15°C at night), the nighttime heat retention time is short, and the risk of icing increases in the early morning hours. The uniform thermal management design leads to delayed de-icing of the blade tips. Due to the high wind speed and large curvature of the blade tip, the icing rate is higher than that of the root, but the traditional uniform PCM layer cannot provide priority heating.

[0005] Imbalance between structural design and material application: The existing solution simply fills the cavity with PCM, failing to address the problem of uneven material distribution under centrifugal force, resulting in PCM enrichment at the root of the blade and failure at the tip.

[0006] Existing technologies cannot simultaneously meet the three requirements of continuous anti-freeze during the day and night, rapid de-icing of blade tips, and lightweight integration. There is an urgent need for an innovative solution that integrates gradient thermal management, zoned phase change temperature control, and structural function integration. Summary of the Invention

[0007] To solve the above problems, the present invention discloses an antifreeze wind turbine blade based on phase change material, comprising a laminated structure from the leeward side to the windward side:

[0008] a) The thermal conductivity of the leeward outer layer (including thermal insulation function) is ≤ 0.03 W / (m·K);

[0009] b) leeward PCM layer, containing a second phase change material with a phase change temperature of T1;

[0010] c) a transitional thermal conductive layer having an anisotropic characteristic of in-plane thermal conductivity greater than out-of-plane thermal conductivity;

[0011] d) The windward side PCM layer contains the first phase change material with a phase change temperature of T2 and satisfies

[0012] T2<T1;

[0013] e) Windward side outer layer (including light and heat functions).

[0014] Furthermore, the windward side outer layer is a metal structural layer, and its surface is covered with a photothermal coating, its solar absorption rate α≥0.92, and infrared emissivity ε≤0.15, and the leeward side outer layer includes an insulation layer, which is an independent insulation layer or a structure-insulation integrated layer.

[0015] Furthermore, the phase transition temperature T2 of the windward side PCM layer and the phase transition temperature T1 of the leeward side PCM layer satisfy: ΔT = T1 - T2 ≥ 3°C, and T2∈[0,20]°C, T1∈[5,25]°C.

[0016] Furthermore, the insulation layer includes an aerogel felt or basalt fiber reinforced layer. When it is an independent insulation layer, the leeward outer skin, such as a metal structural layer, is covered on the outside of the independent insulation layer. When it is an integrated structure-insulation layer, it includes:

[0017] a) Reinforced skeleton: basalt fiber or carbon fiber three-dimensional braid;

[0018] b) Insulation matrix: dispersed with nano-aerogel particles and density ≤ 0.6g / cm 3 Lightweight filler;

[0019] c) Anti-scour surface: short fiber reinforced polyurethane layer.

[0020] Furthermore, the basalt fiber needs to be hydrophobic treated (contact angle ≥ 120°).

[0021] Furthermore, the transition heat-conducting layer is a porous structure with a gradually changing porosity.

[0022] Furthermore, the porosity changes gradually from η1≤40% to η2≥70% from the blade tip to the root, and the porosity satisfies η=0.3+0.5(X / L) (X: distance from the opening to the tip, L: blade length).

[0023] Furthermore, the porous structure includes metal honeycomb, carbon fiber honeycomb or metallized polymer foam.

[0024] Furthermore, in the windward-side PCM layer and the leeward-side PCM layer, the phase change temperature of the region near the blade tip is lower than the phase change temperature of the region near the blade root.

[0025] Furthermore, the tip area refers to the area from the tip of the blade to 1 / 3 of the total length of the blade, and the root area refers to the remaining area of ​​the blade except the tip area. The phase change temperature of the tip area of ​​the windward blade is ∈ [0, 20] ℃, the phase change temperature of the root area of ​​the windward blade is ∈ [0, 20] ℃, the phase change temperature of the tip area of ​​the leeward blade is ∈ [5, 25] ℃, and the phase change temperature of the root area of ​​the leeward blade is ∈ [5, 25] ℃.

[0026] The present invention adopts the above scheme, and its beneficial effects are as follows: through the directional heat transfer path of leeward side insulation → transition thermal conductive layer speed control → windward side heat absorption, heat loss is reduced, thereby improving thermal management efficiency. In addition, the double PCM layer + transition thermal conductive layer work together to achieve continuous antifreeze day and night, which is longer than the single-layer PCM, breaking through the antifreeze continuity. At the same time, through the gradual differentiation design of the porosity of the transition thermal conductive layer, it can achieve tip-priority deicing, lightweighting and vibration fatigue prevention. The present invention introduces a photothermal coating on the outer surface of the windward surface to improve the daytime heat absorption efficiency, shorten the PCM heat storage time, and improve the anti-icing performance. The design of the insulation layer can block the intersection of cold and hot on the leeward side, avoid internal condensation, and at the same time transfer more heat to the outside of the windward surface under low temperature conditions, reducing the transfer to other areas. In addition, the present invention also proposes a differentiated design in which different phase change temperatures are adopted near the blade tip and near the blade root on the same layer of PCM material. Through the zoning strategy of "aggressive deicing at the tip and robust anti-freezing at the root", the working safety of the blade tip is improved, the thawing efficiency is increased, and the insulation time is maintained, which is particularly suitable for ultra-low temperature wind farms below -25°C. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is the overall appearance of the fan blade generator of this application;

[0028] Figure 2 A cross-sectional view of a prior art fan blade unit of the present application;

[0029] Figure 3 This is a cross-sectional view of the fan blade unit according to the first embodiment of the present application;

[0030] Figure 4 This is an exploded cross-sectional view of a fan blade unit according to the first embodiment of the present application;

[0031] Figure 5 This is a schematic diagram of a transitional heat conducting layer according to a first embodiment of the present application;

[0032] Figure 6 This is a timing diagram of the thermal cycle mechanism of the first embodiment of the present application;

[0033] Figure 7 This is a schematic diagram of another transitional heat conductive layer of the present application.

[0034] In the figure: 1-wind turbine blade; 11-windward side outer layer; 12-PCM layer; 13-leeward side insulation layer, 14-leeward side outer layer; 21-photothermal coating; 22-windward side outer layer; 23-windward side PCM layer; 24-transition thermal conductive layer; 25-leeward side PCM layer; 26-leeward side insulation layer; 27-leeward side outer layer. DETAILED DESCRIPTION

[0035] The present invention will be described in detail below with reference to the accompanying drawings.

[0036] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0037] like Figure 1 As shown in Figure 1, a typical wind turbine blade includes a blade tip area and a blade root area. The blade tip area is located at the far end, and the blade root area is located near the center of the blade's rotation axis. Figure 2 Cross-sectional view, the blade unit is along the leeward side to the windward side, including the leeward side outer layer 14, the leeward side insulation layer 13, the PCM layer 12 and the windward side outer layer 11, the leeward side insulation layer 13 is an insulation material, the insulation material is dispersed with nano aerogel particles and has a density of ≤0.6g / cm 3 The lightweight filler has a thermal conductivity of ≤0.03W / (m·K) and includes an aerogel felt or basalt fiber reinforcement layer. Both the leeward outer layer 14 and the windward outer layer 11 are metal structural layers. In this embodiment, the PCM layer 12 is a phase change material with a phase change temperature T∈[3,5]°C. The thermal change mechanism is as follows:

[0038] Daytime heat storage stage: During the daytime, sunlight shines on the leeward outer layer 14 and the windward outer layer 11. Heat penetrates the metal skin layer and is transferred to the PCM layer 12. The PCM layer absorbs the heat and undergoes phase change and melting (from solid to liquid), completing heat storage.

[0039] Nighttime antifreeze stage: When the ambient temperature drops below freezing, the PCM layer undergoes a phase change and solidifies (liquid to solid), releasing stored heat to achieve thawing.

[0040] In this solution, the insulation layer 13 and the leeward outer layer 14 are two independent parts of material. Another solution is to design the insulation layer 13 and the leeward outer layer 14 as a composite material, that is, a structure-insulation integrated layer, which can not only keep warm but also serve as the outer layer of the blade to resist the environment, including:

[0041] a) Reinforced skeleton: basalt fiber or carbon fiber three-dimensional braid, wherein the basalt fiber needs to be hydrophobic treated (contact angle ≥ 120°).

[0042] b) Insulation matrix: dispersed with nano-aerogel particles and density ≤ 0.6g / cm 3 Lightweight filler;

[0043] c) Anti-scour surface: short fiber reinforced polyurethane layer.

[0044] like Figure 3 、 4 A cross-sectional view of a blade according to another embodiment is shown, wherein the stacked structure from the leeward side to the windward side of the blade comprises:

[0045] a) leeward outer layer 27,

[0046] b) leeward side insulation layer 26, including insulation material with a thermal conductivity of ≤ 0.03 W / (m·K);

[0047] c) leeward PCM layer 25, containing a second phase change material with a phase change temperature T1;

[0048] d) a transitional heat-conducting layer 24 having an anisotropic characteristic of in-plane thermal conductivity greater than out-of-plane thermal conductivity;

[0049] e) The windward side PCM layer 23 contains a first phase change material with a phase change temperature T2, and satisfies T2 < T1;

[0050] f) windward side outer layer 22;

[0051] g) a photothermal coating 21 having a solar absorptivity α ≥ 0.92 and an infrared emissivity ε ≤ 0.15;

[0052] The windward outer layer is a metal structural layer. The phase change temperature T2 of the windward PCM layer and the phase change temperature T1 of the leeward PCM layer satisfy: ΔT = T1 - T2 ≥ 3°C, and T2∈[0,20]°C, T1∈[5,25]°C.

[0053] like Figure 5 As shown, the transitional thermal conductive layer 24 is a porous structure with a gradually varying porosity, with the porosity gradually varying from η1 ≤ 40% to η2 ≥ 70% from the blade tip to the root. The porosity satisfies η = 0.3 + 0.5 (X / L) (X: distance from the tip to the opening; L: blade length). The porous structure comprises a metal honeycomb, a carbon fiber honeycomb, or a metallized polymer foam.

[0054] like Figure 6 As shown in the timing diagram of the thermal cycle mechanism, the antifreeze blade of the present invention achieves all-weather antifreeze through a stepped thermal management mechanism. Its working process is divided into two core stages:

[0055] The first stage: gradual heat storage stage (active energy storage period):

[0056] Step ① Photothermal conversion: Sunlight irradiates the photothermal coating 21 (α≥0.92) on the windward outer layer 22 of the blade, and the temperature of the coating 21 rises to 60-80°C. The heat is then transferred to the windward PCM layer 23 through the metal skin of the windward outer layer 22.

[0057] Step ② Rapid phase change heat storage: The PCM on the windward side (phase change temperature T2∈[0,20]℃) absorbs heat and melts (solid→liquid), completing the main heat storage within a period of time (for example: 2-3 hours).

[0058] Step ③ Delayed transfer: Heat is transferred to the leeward side through the transitional heat conducting layer 24. Due to the gradient opening design of the transitional heat conducting layer 24 (opening rate at the tip ≤ 40%), the heat transfer speed to the leeward side PCM layer 25 is delayed.

[0059] Step ④ Deep heat storage: The PCM on the leeward side (phase change temperature T1∈[5,25]℃) is gradually filled within a certain period of time (for example: 4-6 hours) to form a second heat storage layer.

[0060] Technical effect: Compared with single-layer PCM, double-layer PCM has a higher total heat storage capacity during the day and avoids PCM thermal failure caused by high temperature.

[0061] The second stage: Night antifreeze stage (continuous energy release period):

[0062] Step 5: Prioritize de-icing response: When the ambient temperature drops below freezing, the PCM layer 23 on the windward side first undergoes phase change and solidifies (liquid to solid), releasing most of the latent heat in a short period of time, keeping the blade surface temperature above 0°C.

[0063] Step 6: Slowly release heat: The leeward PCM layer 25 slowly releases heat through the transition heat conductive layer 24 (out-of-plane thermal conductivity ≤ 1 W / m·K), forming a continuous heat flow.

[0064] Step 7: Directional heat locking: The transitional thermal conductive layer blocks heat loss to the leeward side through its anisotropic thermal conductivity (in-plane / out-of-plane thermal conductivity ratio > 10), ensuring that most of the heat is directed to the windward side.

[0065] Step ⑧ Long-term antifreeze: In a low-temperature environment for a certain period of time (such as 6 hours), the blade surface temperature is always 3-5°C higher than the ambient temperature, and the ice thickness is controlled to meet the IEC61400-23 standard.

[0066] As can be seen from the above, the transitional heat-conducting layer used in this embodiment has the following benefits:

[0067] During the day: High in-plane thermal conductivity (>15W / m·K) ensures heat transfer to the leeward PCM layer, and the gradient opening design prevents rapid saturation of heat storage.

[0068] At night, low out-of-plane thermal conductivity (<1 W / m·K) blocks heat backflow, extending the heat release time of the leeward PCM layer.

[0069] like Figure 7 As shown in FIG. , another embodiment of a phase change material is shown. The tip region refers to the area from the tip of the blade to 1 / 3 of the total length of the blade. The root region refers to the remaining area of ​​the blade excluding the tip region. The phase change temperature of the tip region is lower than the phase change temperature of the region near the root region. For example, the phase change temperature of the windward blade tip region is ∈ [0, 20]°C, the phase change temperature of the windward blade root region is ∈ [0, 20]°C, the phase change temperature of the leeward blade tip region is ∈ [5, 25]°C, and the phase change temperature of the leeward blade root region is ∈ [5, 25]°C. Through this design, the effect of prioritizing the thawing of the blade tip region and slowly and continuously thawing the blade root region can be achieved, thereby controlling the thawing area of ​​the blade.

[0070] The same or similar numbers in the figures of the embodiments of the present invention correspond to the same or similar parts. In the description of the present invention, it should be understood that if the terms "up", "down", "left", "right", "front", "back", etc. indicate the orientation or position relationship, they are based on the orientation or position relationship shown in the figure. This is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operate in a specific orientation. Therefore, the terms describing the position relationship in the figures are only used for illustrative purposes and cannot be understood as limiting the present invention. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to specific circumstances.

[0071] It should be noted that when a component is referred to as being "connected" to another component, it may be directly connected to the other component or there may be a component in the middle; when a component is referred to as being "fixed" to another component, it may be directly fixed to the other component or there may be a component in the middle, and it may be done by effective means such as bonding, welding, riveting, bolts, etc., which are not listed one by one in this application; when a component is referred to as being "movable" with another component, it may be done by rotation or sliding.

[0072] The present application is not limited to the aforementioned specific embodiments, and the present invention extends to any new features or any new combination disclosed in this specification, as well as any new method or process steps or any new combination disclosed.

Claims

1. An antifreeze wind turbine blade based on phase change material, characterized by: Includes a stacked structure from the leeward side to the windward side: a) Outer layer on the leeward side (including thermal insulation function); b) leeward PCM layer, containing a second phase change material with a phase change temperature of T1; c) a transitional thermal conductive layer having an anisotropic characteristic of in-plane thermal conductivity greater than out-of-plane thermal conductivity; d) a windward-side PCM layer comprising a first phase change material having a phase change temperature T2, where T2 is less than T1; e) Windward side outer layer (including light and heat functions).

2. The antifreeze wind turbine blade based on phase change material according to claim 1, characterized in that: The windward side outer layer is a metal structural layer, and its surface is covered with a photothermal coating, its solar absorption rate α≥0.92, and infrared emissivity ε≤0.

15. The leeward side outer layer includes an insulation layer, which is an independent insulation layer or a structure-insulation integrated layer.

3. The antifreeze wind turbine blade based on phase change material according to claim 1, characterized in that: The phase transition temperature T2 of the windward side PCM layer and the phase transition temperature T1 of the leeward side PCM layer satisfy: ΔT = T1 - T2 ≥ 3°C, and T2∈[0,20]°C, T1∈[5,25]°C.

4. The antifreeze wind turbine blade based on phase change material according to claim 2, characterized in that: The thermal insulation layer includes an aerogel felt or a basalt fiber reinforced layer. When it is a structure-thermal insulation integrated layer, it includes: a) Reinforced skeleton: basalt fiber or carbon fiber three-dimensional braid; b) Insulation matrix: dispersed with nano-aerogel particles and density ≤ 0.6g / cm 3 Lightweight filler; c) Anti-scour surface: short fiber reinforced polyurethane layer.

5. The antifreeze wind turbine blade based on phase change material according to claim 1, characterized in that: The transition heat-conducting layer is a porous structure with a gradually changing porosity.

6. The antifreeze wind turbine blade based on phase change material according to claim 5, characterized in that: The porosity changes gradually from η1≤40% to η2≥70% from the blade tip to the root, and the porosity satisfies η=0.3+0.5(X / L) (X: distance from the opening to the tip, L: blade length).

7. The antifreeze wind turbine blade based on phase change material according to claim 5, characterized in that: The porous structure includes metal honeycomb, carbon fiber honeycomb or metallized polymer foam.

8. The antifreeze wind turbine blade based on phase change material according to claim 1, characterized in that: In the windward side PCM layer and the leeward side PCM layer, the phase transition temperature of the region near the blade tip is lower than the phase transition temperature of the region near the blade root.

9. The antifreeze wind turbine blade based on phase change material according to claim 8, characterized in that: The tip area refers to the area from the tip of the blade to 1 / 3 of the total length of the blade, and the root area refers to the remaining area of ​​the blade except the tip area. The phase change temperature of the tip area of ​​the windward blade is ∈[0,20]℃, the phase change temperature of the root area of ​​the windward blade is ∈[0,20]℃, the phase change temperature of the tip area of ​​the leeward blade is ∈[5,25]℃, and the phase change temperature of the root area of ​​the leeward blade is ∈[5,25]℃.

10. The antifreeze wind turbine blade based on phase change material according to claim 1, characterized in that: The photothermal coating comprises a Cr-Cr2O3 metal ceramic composite layer or a vertical graphene-based coating with a thickness of 0.1 to 0.3 mm.

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