Wind Turbines

Abstract

The present invention relates to a wind turbine (1) comprising a main gearbox (9) lubricated and / or cooled by means of oil (10), and a thermosiphon cooling system (11) for cooling the oil (10). The thermosiphon cooling system (11) solves the main challenges faced by oil cooling systems in wind turbines (1). The high efficiency of the evaporative heat transfer mechanism enables the required heat load to be transferred in a system of relatively small size. In this way, the installation space can be reduced. Because the thermosiphon cooling system (11) has no moving parts, the thermosiphon cooling system (11) has no maintenance requirements throughout the life cycle of the wind turbine (1). Costs can be saved because the simplification of the thermosiphon cooling system adds great value to the system business case.

Description

Technical Field

[0001] The invention relates to a wind turbine. Background Art

[0002] A wind turbine has a nacelle, a hub rotatably supported at the nacelle, a generator arranged inside the nacelle, and a main gearbox arranged between the hub and the generator. The main gearbox is lubricated and cooled by means of oil. During operation of the wind turbine, the oil needs to be cooled. According to the applicant's internal knowledge, in the wind industry, there are two main cooling methods for oil cooling.

[0003] In what is called an active oil to air system, heat is extracted from the oil in an oil / air heat exchanger by driving air into the cooler by electrical or mechanical ventilation. In what is called an oil / coolant / air system, a pump-driven coolant extracts heat from the oil in the oil / coolant heat exchanger. The coolant then circulates into an air / coolant heat exchanger where it can be cooled passively using airflow or actively by using ventilation to drive air. Summary of the invention

[0004] It is an object of the present invention to provide an improved wind turbine.

[0005] Hence, a wind turbine is provided, comprising a main gearbox lubricated and / or cooled by means of oil, and a thermosiphon cooling system for cooling the oil.

[0006] Thermosiphon cooling systems solve the main challenges faced by oil cooling systems in wind turbines. The high efficiency of the evaporative heat transfer mechanism enables the required heat load to be transferred in a relatively small size system. In this way, the installation space can be reduced. Because the thermosiphon cooling system has no moving parts, there are no maintenance requirements for the thermosiphon cooling system throughout the life cycle of the wind turbine. Cost savings can be achieved due to the simplicity of the thermosiphon cooling system, which adds great value to the system business case.

[0007] A "thermosiphon cooling system" in this context should be understood as a passive heat exchange system based on natural convection, which circulates a fluid, in particular a working fluid, without the need for a mechanical or electrical pump. In other words, a thermosiphon cooling system is a passive cooling system and, therefore, has no moving parts. Thus, a thermosiphon cooling system is pump-less or pump-free. "Pump-less or pump-less" means that a thermosiphon cooling system does not have a pump to circulate the working fluid.

[0008] Preferably, the wind turbine comprises a nacelle accommodating a main gearbox. A hub is rotatably supported at the nacelle. Inside the nacelle, a generator may be provided. The main gearbox may be arranged between the hub and the generator. The hub supports a plurality of rotor blades. Two or three rotor blades may be provided here. The nacelle may be box-shaped.

[0009] According to an embodiment, the thermosiphon cooling system forms a closed loop.

[0010] "Closed loop" or "closed circuit" in this context means that the working fluid circulating in the thermosiphon cooling system cannot leave the thermosiphon cooling system.

[0011] According to further embodiments, a thermosiphon cooling system includes an evaporator, a condenser, and a tube coupling the evaporator to the condenser such that the thermosiphon cooling system forms a closed loop.

[0012] Preferably, two tubes are provided. The liquid tube is capable of conveying liquid working fluid from the condenser to the evaporator. The gaseous or steam tube is capable of conveying gaseous working fluid from the evaporator to the condenser. The tube is a corrugated metal hose or tubing to absorb vibrations of the operating wind turbine and to optimize packaging and transport handling during the transport process. All connections between the tubes, evaporator and condenser are preferably brazed to eliminate the risk of leakage during the life cycle of the thermosiphon cooling system.

[0013] According to a further embodiment, the condenser is arranged above the evaporator when viewed in the height direction.

[0014] In this way, gravity forces the condensed working fluid from the condenser back to the evaporator.

[0015] According to a further embodiment, the wind turbine further comprises a nacelle accommodating the main gearbox, wherein the evaporator is arranged inside the nacelle, and wherein the condenser is arranged outside the nacelle.

[0016] Preferably, the evaporator is arranged at a side wall of the nacelle.More than one evaporator and / or more than one condenser may be provided.

[0017] According to a further embodiment, the condenser is arranged on top of the nacelle.

[0018] In particular, the condenser is arranged on or at a ceiling or ceiling of the nacelle.A holder may be provided for holding the condenser.

[0019] According to a further embodiment, the condenser is inclined at an inclination angle towards a horizontal position.

[0020] In this way, the condensed working fluid collects at the lowest point of the collector, from which point it is conducted to the evaporator by means of one of the aforementioned tubes.

[0021] According to further embodiments, the wind turbine further comprises a fan for forcing air through the condenser.

[0022] The fan is optional. The fan can be a ventilator. More than one fan can be provided. The fan increases the amount of heat that can be removed from the condenser.

[0023] According to a further embodiment, the main gearbox is coupled to the evaporator by means of a hose or a pipe.

[0024] Hot oil is directed from the main gearbox through one of a plurality of tubes to the evaporator. In the evaporator, heat is transferred from the oil to the working fluid, which then evaporates and flows to the condenser. The cooled oil leaves the evaporator and is directed back to the main gearbox through another of the plurality of tubes. A pump may be provided to circulate the oil. The pump is optional. The main gearbox itself is capable of circulating the oil. A "hose" is a flexible hollow tube that carries fluid from one location to another. A "tube" in this context is a non-flexible hollow tubular object that is designed to carry fluid from one location to another.

[0025] According to a further embodiment, the wind turbine further comprises a working fluid, in particular a refrigerant, circulating in the thermosiphon cooling system.

[0026] A "refrigerant" in this context is a substance or mixture, usually a fluid, used in heat pump and refrigeration cycles. In most cycles, it undergoes a phase change from liquid to gas and back again. For example, 1,1,1,2-tetrafluoroethane (R-134a) can be used as a working fluid. For example, the working fluid can also be water.

[0027] Further possible implementations or alternative solutions of the present invention also include combinations of features described above or below with respect to the embodiments (which are not explicitly mentioned herein). Those skilled in the art may also add individual or separate aspects and features to the most basic form of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further embodiments, features and advantages of the present invention will become apparent from the following description and the dependent claims, taken in conjunction with the accompanying drawings, in which:

[0029] Figure 1 shows a perspective view of a wind turbine according to one embodiment;

[0030] Figure 2 shows a perspective view of a wind turbine rotor blade according to one embodiment;

[0031] Figure 3 shows a side view of a nacelle according to one embodiment; and

[0032] Figure 4 Shown according to Figure 3 Rear view of the cabin.

[0033] In the drawings, like reference numbers indicate similar or functionally equivalent elements unless otherwise indicated. DETAILED DESCRIPTION

[0034] Figure 1 A wind turbine 1 according to an embodiment is shown.

[0035] The wind turbine 1 comprises a rotor 2 connected to a generator (not shown) arranged inside a nacelle 3. The nacelle 3 is arranged at the upper end of a tower 4 of the wind turbine 1. The tower 4 has a plurality of tower sections arranged on top of each other. The tower 4 may be named a wind turbine tower.

[0036] The rotor 2 comprises three rotor blades 5. The rotor blades 5 are connected to a hub 6 of the wind turbine 1. Such a rotor 2 may have a diameter varying in a range from, for example, 30 to 160 meters or even more. The rotor blades 5 are subject to high wind loads. At the same time, the rotor blades 5 need to be lightweight. For these reasons, the rotor blades 5 in modern wind turbines 1 are manufactured from fiber-reinforced composite materials. Among them, glass fibers are generally preferred to carbon fibers for cost reasons. Glass fibers in the form of unidirectional fiber mats are often used.

[0037] Figure 2 A rotor blade 5 according to one embodiment is shown.

[0038] The rotor blade 5 comprises an aerodynamically designed portion 7 , which is shaped for optimal utilization of wind energy, and a blade root 8 for connecting the rotor blade 5 to the hub 6 .

[0039] Figure 3 and Figure 4 A nacelle 3 according to one embodiment is shown.

[0040] The nacelle 3 has a coordinate system including an x-direction or depth direction x, a y-direction or height direction y and a z-direction or width direction z. The nacelle 3 has a front portion 3A and a rear portion 3B. The rear portion 3B is not Figure 4 Shown in.

[0041] The nacelle 3 comprises a main gearbox 9. The main gearbox 9 may be arranged between the hub 6 and a generator (not shown). The main gearbox 9 is arranged in a front part 3A of the nacelle 3, whereas the generator is arranged in a rear part of the nacelle 3. The main gearbox 9 is lubricated and cooled by means of oil 10. During operation of the wind turbine 1, the oil 10 must be cooled.

[0042] In order to cool the oil 10, a thermosiphon cooling system 11 is provided. A "thermosiphon cooling system" in this context should be understood as a passive heat exchange system based on natural convection, which circulates a fluid without the need for a mechanical pump. In other words, the thermosiphon cooling system 11 is a passive cooling system and therefore has no moving parts.

[0043] The thermosiphon cooling system 11 comprises an evaporator 12 arranged in the nacelle 3, in particular, in the front part 3A. The evaporator 12 is connected to a condenser 13 by means of pipes 14, 15. The evaporator 12 is connected to the main gearbox 9 or to the oil sump of the main gearbox 9 by means of pipes 16, 17. The condenser 13 is arranged outside the nacelle 3. Preferably, the condenser 13 is arranged on the top of the nacelle 3, in particular on the top of the front part 3A, in particular, on the roof of the nacelle 3. The condenser 13 can be installed at any position on the nacelle 3, as long as a sufficient vertical distance is maintained to generate the required gravity to keep the required liquid flowing back to the evaporator 12. When viewed in the height direction y, the condenser 13 is arranged above the evaporator 12. In other words, when viewed in the height direction y, the evaporator 12 is arranged below the condenser 13.

[0044] The condenser 13 is inclined towards a horizontal position 18. The horizontal position 18 is arranged parallel to the width direction z. The condenser 13 is arranged at an inclination angle α towards the horizontal position 18. The inclination angle α may have a value of 1 to 15°. The tube 14 is connected to the lowest point 19 of the condenser 13. The tube 15 is connected to the highest row 20 of the condenser 13.

[0045] Tubes 14 and 15 are corrugated metal hoses. Tube 14 is capable of transporting a working fluid 21 in liquid phase from the condenser 13 to the evaporator 12. For this reason, tube 14 can be named as a liquid tube. The working fluid 21 can be a refrigerant. A "refrigerant" in this context is a substance or mixture, usually a fluid, used in heat pumps and refrigeration cycles. In most cycles, it undergoes a phase change from liquid to gas and back again. For example, 1,1,1,2-tetrafluoroethane (R-134a) can be used as the working fluid 21.

[0046] The pipe 15 is capable of transporting the working fluid 21 in the gas phase from the evaporator 12 to the condenser 13. For this reason, the pipe 15 can be named a gaseous pipe. All connections between the pipes 14, 15, the evaporator 12 and the condenser 13 are brazed to eliminate the risk of leakage during the use cycle of the thermosiphon cooling system 11.

[0047] The thermosiphon cooling system 11 functions as follows. Oil 10 circulates from the main gearbox 9 to the evaporator 12 and back through pipes 16, 17. Pipe 16 conducts hot oil 10 from the main gearbox 9 to the evaporator 12. Pipe 17 conducts cooled oil 10 from the evaporator 12 back to the main gearbox 9. To circulate the oil 10, an optional pump (not shown) may be provided.

[0048] In the evaporator 12, heat is transferred from the oil 10 to the working fluid 21. The working fluid 21 evaporates and is directed to the condenser 13 through the tube 15. The gaseous working fluid 21 condenses in the condenser 13 while transferring heat to the surroundings 22 of the nacelle 3. The condenser 13 is cooled by means of the air in the surroundings 22 absorbing the heat. In this way, the heat extracted by the working fluid 21 is passively cooled by the air. Optionally, a fan 23 may be provided that forces air 24 through the condenser 13. The fan 23 may be mounted in front of the condenser 13 to push the air 24 through the condenser 13. The fan 23 may also be mounted behind the condenser 13 to pull the air 24 through the condenser 13.

[0049] After condensation, the working fluid 21 is directed back to the evaporator 12 by means of the tube 14. Due to the fact that the condenser 13 is inclined and the tube 14 is connected to the lowest point 19 of the condenser 13, the liquid working fluid 21 can be prevented from returning to the condenser 13. Then, the working fluid 21 directed back to the evaporator 12 evaporates again in the evaporator 12 and is directed back to the condenser 13. In this way, a closed loop of the working fluid 21 can be provided.

[0050] As mentioned previously, a refrigerant may be used as the working fluid 21. However, different fluids may be used depending on the required system pressure and operating temperature range. The thermosiphon cooling system 11 is completely passive, meaning that it eliminates the need for a pump or fan. The working fluid 21 circulates between the evaporator 12 and the condenser 13 by the force generated by the pressure difference between the condenser 13 and the evaporator 12. The present design allows for the condenser 13 to be mounted vertically above the evaporator 12 to use gravity that facilitates the circulation of the condensed working fluid 21 back to the evaporator 12. In addition, the condenser 13 is tilted at an inclination angle α to force the condensed working fluid 21 to return to the evaporator 12 through the tube 14.

[0051] The condenser 12 is mounted inside the nacelle 3. Thus, the design eliminates the risk of any oil leaking into the surrounding environment 22. The thermosiphon cooling system 11 is designed to be assembled, sealed and filled by the supplier before delivery to the site to eliminate the cost of assembly in production and save costs in logistics and transportation. The thermosiphon cooling system 11 is designed as a complete assembled unit to allow a simple installation process. This mitigates the risk of installation errors during the assembly and filling process required in current solutions.

[0052] The thermosiphon cooling system 11 solves the main challenges faced by oil cooling systems in wind turbines 1. The high efficiency of the evaporative heat transfer mechanism enables the required heat load to be transferred in a system of relatively small size. In this way, the installation space can be reduced.

[0053] Because the thermosiphon cooling system 11 is already sealed and brazed at installation and has no moving parts, the thermosiphon cooling system 11 has no maintenance requirements throughout the life of the wind turbine 1. Cost savings can be achieved because the simplification of the thermosiphon cooling system adds tremendous value to the system business case. A reduction of approximately 30% in initial cost can be achieved. Savings of more than 35% in total costs, including life cycle operating costs of the wind turbine 1, can be achieved.

[0054] Although the invention has been described in terms of preferred embodiments, it will be apparent to those skilled in the art that modifications in all embodiments are possible.

Claims

1. A wind turbine (1) comprising a main gearbox (9) lubricated and / or cooled by means of oil (10), and a thermosiphon cooling system (11) for cooling the oil (10), wherein: The thermosiphon cooling system (11) comprises an evaporator (12), a condenser (13), and a first tube (14) and a second tube (15), wherein the first tube (14) and the second tube (15) connect the evaporator (12) to the condenser (13), so that the thermosiphon cooling system (11) forms a closed loop, wherein the first tube (14) transports a liquid-phase working fluid (21) from the condenser (13) to the evaporator (12) and the second tube (15) transports a gas-phase working fluid (21) from the evaporator (12) to the condenser (13), wherein the main gearbox (9) is connected to the evaporator (12) by means of a third tube (16) and a fourth tube (17), wherein, when viewed in a height direction (y), the condenser (13) is arranged above the evaporator (12).

2. The wind turbine according to claim 1, characterized in that The wind turbine further comprises a nacelle (3) accommodating the main gearbox (9), wherein the evaporator (12) is arranged inside the nacelle (3), and wherein the condenser (13) is arranged outside the nacelle (3).

3. The wind turbine according to claim 2, characterized in that The condenser (13) is arranged on the top of the nacelle (3).

4. A wind turbine according to any one of claims 1 to 3, characterized in that The condenser (13) is inclined at an inclination angle (α) towards a horizontal position (18).

5. The wind turbine according to any one of claims 1 to 3, characterized in that The wind turbine also includes a fan (23) for forcing air (24) through the condenser (13).

6. A wind turbine according to any one of claims 1 to 3, characterized in that The wind turbine also includes a refrigerant circulating in the thermosiphon cooling system (11).

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