Offshore wind turbine nacelle cooling system

Abstract

This invention discloses a cooling system for offshore wind turbine nacelles, belonging to the field of thermal management technology. The offshore wind turbine nacelle cooling system includes: a storage tank for storing liquid cooling material; a flow controller located above the storage tank for regulating the flow rate of the liquid cooling material output from the storage tank; a cooling module located above the flow controller, in contact with the target device inside the wind turbine nacelle, for cooling the target device using the liquid cooling material output from the storage tank; a steam collection pipe located above the cooling module for collecting the gaseous cooling material that has evaporated after cooling the target device; a condenser located above the steam collection pipe for condensing the gaseous cooling material into liquid cooling material using sea air; and a return pipe connecting the condenser and the storage tank for transferring the liquid cooling material from the condenser to the storage tank. A natural circulation system with gravity return is constructed, utilizing the latent heat of phase change to achieve high-efficiency heat dissipation.

Description

Technical Field

[0001] This invention belongs to the field of thermal management technology, specifically relating to a cooling system for offshore wind turbine nacelles. Background Technology

[0002] As global offshore wind power develops towards deeper and deeper waters, the capacity of a single unit is rapidly entering the 15MW+ level. In order to solve the problem of high losses in low-voltage, high-current, long-distance transmission, the mainstream solutions in the industry place core electrical components such as converters and transformers inside the nacelle, making the nacelle the high-density heat generation center of the whole unit. Under full load conditions, the heat loss of the whole unit can reach 600-800kW.

[0003] Current cooling technologies for offshore wind turbine nacelles include: integrated single-phase water cooling systems, forced air cooling systems, and discrete phase change cooling technologies for individual components. Among these, the mainstream integrated single-phase water cooling system is nearing its performance limits and cannot meet the demands of 15MW+ ultra-large turbines; forced air cooling systems also cannot meet the heat dissipation requirements of large-capacity offshore turbines; and discrete phase change cooling technologies for individual components lack a coherent system and cannot solve the overall thermal management challenges of the turbine. Existing cooling technologies for offshore wind turbine nacelles fail to balance cooling efficiency, nacelle load, and total lifecycle cost. Summary of the Invention

[0004] The purpose of this invention is to provide a cooling system for offshore wind turbine nacelles that can solve the problems of low cooling efficiency, large nacelle load, and high life-cycle cost of existing cooling technologies for offshore wind turbine nacelles.

[0005] In a first aspect, embodiments of the present invention provide a cooling system for an offshore wind turbine nacelle, comprising: Storage tanks are used to store liquid cooling materials. A flow controller, located above the storage tank, is used to regulate the flow rate of the liquid cooling material output from the storage tank; A cooling module is located above the flow controller and in contact with the target device inside the wind turbine nacelle. It is used to cool the target device with the liquid cooling material output from the storage tank. A vapor collection pipe, located above the cooling module, is used to collect the vaporized cooling material that has evaporated into a gaseous state after cooling the target device. A condenser, located above the steam collecting pipe, is used to condense the gaseous cooling material into a liquid cooling material by means of sea breeze; A return pipe, connected between the condenser and the storage tank, is used to transfer the liquid cooling material in the condenser to the storage tank.

[0006] Optionally, the target device includes a generator, and the cooling module includes a generator cooling unit; the generator cooling unit has an annular cavity, the stator of the generator is sealed in the annular cavity, and the annular cavity is filled with the liquid cooling material; an air gap is included between the stator and rotor of the generator, and a cooling wall is formed on the side of the annular cavity near the air gap; The generator cooling unit is used to cool the stator of the generator through the liquid cooling material in the annular cavity; during the rotation of the generator rotor, the cooling wall surface cools the heat generated by the eddy currents excited in the air gap of the generator rotor.

[0007] Optionally, a steam collecting chamber is provided at the top of the annular cavity, and the outlet of the steam collecting chamber is connected to the steam collecting pipe; the liquid inlet of the annular cavity is located at the bottom and is connected to the flow controller.

[0008] Optionally, the target device includes a converter, and the cooling module includes a converter cooling unit; the converter cooling unit includes a plurality of vertically arranged heat exchange fins, each heat exchange fin having a sealed cavity filled with the liquid cooling material; the converter is in contact with the outer surface of the heat exchange fins. The converter cooling unit is used to cool the converter using liquid cooling material in the sealed cavity.

[0009] Optionally, the target device includes a gearbox and a transformer, and the cooling module includes a first oil medium cooling unit and a second oil medium cooling unit; the first oil medium cooling unit and the second oil medium cooling unit have a sealed shell, and the sealed shell is filled with the liquid cooling material; the sealed shell is provided with a heat exchange channel; the gearbox is connected to the heat exchange channel of the first oil medium cooling unit, and the transformer is connected to the heat exchange channel of the second oil medium cooling unit; The first oil medium cooling unit is used to cool the lubricating oil in the heat exchange channel through the liquid cooling material of the sealed shell when the lubricating oil of the gearbox flows in the heat exchange channel; The second oil medium cooling unit is used to cool the lubricating oil in the heat exchange channel by means of liquid cooling material inside the sealed housing when the lubricating oil of the transformer flows in the heat exchange channel.

[0010] Optionally, the flow controller includes a proportional regulating valve; The flow controller is used to acquire the temperature and pressure of the target device; and adjust the opening of the proportional control valve according to the temperature and pressure of the target device to adjust the flow rate of the liquid cooling material output from the storage tank.

[0011] Optionally, the flow controller includes a circulating pump, the inlet of which is provided with a filter element, and the outlet of which is provided with a check element; The flow controller is used to assist the reflux pipe in transferring the liquid cooling material in the condenser to the storage tank via the circulation pump.

[0012] Optionally, the steam collecting pipe is provided with a continuous upward angle along the flow direction of the gaseous cooling material.

[0013] Optionally, the return pipe is inclined at a downward angle along the flow direction of the liquid cooling material in the condenser.

[0014] Optionally, the cooling material is an electronic fluorinated liquid.

[0015] The embodiments of the present invention have the following advantages: The offshore wind turbine nacelle cooling system of this invention includes: a storage tank, a flow controller, a cooling module, a steam manifold, a condenser, and a return pipe; the storage tank is used to store liquid cooling material; the flow controller is located above the storage tank and is used to regulate the flow rate of the liquid cooling material output from the storage tank; since the flow controller is located upstream of the liquid path, it can accurately adjust the output flow rate of the cooling material according to the system requirements, ensuring that the cooling material in each parallel wind turbine nacelle branch is always in a stable nucleation boiling range, thus maximizing the heat exchange efficiency. The cooling module, located above the flow controller and in contact with the target components inside the wind turbine nacelle, cools these components using liquid cooling material supplied from the storage tank. Positioning the cooling module above the flow controller and storage tank creates a height difference, facilitating gravity-assisted fluid circulation and reducing reliance on mechanical pump power. Simultaneously, the module directly contacts the heat source, allowing the cooling material to absorb heat and undergo a boiling phase change within the module. The latent heat of this phase change removes heat, significantly improving heat exchange efficiency compared to traditional water cooling that relies solely on temperature rise. This significantly enhances the heat transfer efficiency, enabling it to handle the high heat flux density of 15MW+ units. The steam collection pipe, also located above the cooling module, collects the vaporized cooling material after cooling the target components. Utilizing the natural upward flow of hot steam, the steam collection pipe greatly reduces flow resistance, eliminating the need for additional high-power fans. Furthermore, it collects steam from multiple dispersed heat sources such as generators, converters, and transformers, achieving integrated thermal management at the entire unit level and avoiding the complex piping and maintenance difficulties associated with independent cooling systems for each component. The condenser, located above the steam manifold, condenses the gaseous cooling material into liquid cooling material using sea breeze. Positioning the condenser at the highest point of the system, utilizing natural sea breeze for condensation eliminates the need for additional cooling fans, significantly reducing parasitic energy consumption and improving the unit's net power generation efficiency. Furthermore, the condenser's location above the engine room prevents the direct introduction of salty sea breeze into the engine room, protecting the delicate electrical equipment from corrosion. The return pipe, connecting the condenser and the storage tank, transfers the liquid cooling material from the condenser to the storage tank. Because the condenser is at the highest point and the storage tank at the lower point, the liquid cooling material can automatically flow back to the storage tank by gravity, eliminating the reliance on a return pump in traditional water-cooled systems. This not only saves energy but also eliminates a potential point of mechanical failure, achieving maintenance-free operation. Attached Figure Description

[0016] Figure 1 This is a structural block diagram of a cooling system for an offshore wind turbine nacelle according to an embodiment of the present invention; Figure 2 This is a structural block diagram of the generator cooling unit according to an embodiment of the present invention; Figure 3This is a cross-sectional view of the generator cooling unit according to an embodiment of the present invention; Figure 4 This is a structural block diagram of the converter cooling unit according to an embodiment of the present invention; Figure 5 This is a structural block diagram of the oil medium cooling unit according to an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: Storage tank 11, flow controller 12, cooling module 13, steam manifold 14, condenser 15, return pipe 16, generator 17, converter 18, gearbox 19, transformer 110, first oil medium cooling unit 111, second oil medium cooling unit 112, generator stator 21, generator rotor 22, main shaft 23, steam drum 31, steam drum outlet 32, and annular cavity liquid inlet 33. Detailed Implementation

[0018] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] The terms "first," "second," etc., used in the specification and claims of this invention are used to distinguish similar objects and are not used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention can be implemented in orders other than those illustrated or described herein. Furthermore, in the specification and claims, "and / or" indicates at least one of the connected objects, and the character " / " generally indicates that the preceding and following objects are in an "or" relationship.

[0020] The following detailed description, in conjunction with the accompanying drawings, of a cooling system for an offshore wind turbine nacelle provided by the present invention, through specific embodiments and application scenarios, will be provided in detail.

[0021] Reference Figure 1 The diagram illustrates a structural block diagram of an offshore wind turbine nacelle cooling system according to an embodiment of the present invention. The offshore wind turbine nacelle cooling system may specifically include: Storage tank 11 is used to store liquid cooling materials; A flow controller 12 is located above the storage tank 11 and is used to regulate the flow rate of the liquid cooling material output from the storage tank 11. The cooling module 13 is located above the flow controller 12 and is in contact with the target device inside the wind turbine nacelle. It is used to cool the target device with liquid cooling material output from the storage tank 11. A vapor collection pipe 14 is located above the cooling module 13 and is used to collect the vaporized cooling material that has been cooled to the target device. The condenser 15 is located above the steam collecting pipe 14 and is used to condense the gaseous cooling material into liquid cooling material by sea breeze. The return pipe 16 is connected between the condenser 15 and the storage tank 11 and is used to transfer the liquid cooling material in the condenser 15 to the storage tank 11.

[0022] In this embodiment of the invention, a highly efficient closed-loop circulation architecture utilizing the principles of gravity and phase change is constructed. The system is vertically arranged, with the storage tank as the starting point of the circulation. The liquid cooling material first passes through a flow controller located above it to regulate its output flow rate; then it enters a higher-positioned cooling module, which contacts the heat-generating components inside the wind turbine nacelle. Here, the cooling material absorbs heat and undergoes phase change evaporation, efficiently removing heat using latent heat. The resulting gaseous cooling material rises naturally under buoyancy and enters a steam collection pipe located above the cooling module for unified collection. Next, the steam is transported to the condenser at the highest point of the system, where natural sea breezes serve as a cold source, condensing the high-temperature gaseous working fluid back into a liquid state. Finally, the system uses a return pipe connecting the condenser and the storage tank, utilizing gravitational potential energy to drive the liquid cooling material to automatically return to the storage tank, thus completing the entire cycle.

[0023] The storage tank is made of stainless steel that is resistant to marine corrosion. It is designed to withstand pressure to meet the system's operating pressure requirements. The tank is equipped with level, pressure, and temperature monitoring elements, as well as safety protection and a liquid replenishment interface. It is horizontally installed on the equipment platform at the bottom of the engine room. The liquid outlet is located at the top of the tank, and the liquid return port is located at the bottom of the tank, ensuring that the returned working fluid is fully defoamed before entering the storage tank.

[0024] The flow controller, located above the storage tank and upstream of the liquid circuit, precisely adjusts the flow rate of the output liquid cooling material according to system requirements (such as the real-time heat output of the generator and converter). This ensures that the cooling material in each parallel branch remains within a stable nucleation boiling range, maximizing heat exchange efficiency. Each branch can use an independent flow controller to ensure the stability and controllability of the nucleation boiling process and eliminate the risk of localized drying. Simultaneously, the flow controller decouples the system's storage and cooling functions, allowing the system to operate at lower pressures and reducing the pressure resistance requirements of the storage tank.

[0025] The cooling module, located above the flow controller and in contact with the target device inside the wind turbine nacelle, is used to cool the target device using liquid cooling material supplied from the storage tank. Placing the cooling module above the flow controller and storage tank creates a height difference, which facilitates the use of gravity to assist in driving fluid circulation and reduces reliance on the power of mechanical pumps. At the same time, the module is in direct contact with the heat source, and the cooling material absorbs heat and undergoes a boiling phase change within the module. It uses the latent heat of the phase change to remove heat, which significantly improves heat exchange efficiency compared to traditional water cooling that relies solely on temperature rise to remove heat. This allows it to handle the high heat flux density of 15MW+ units.

[0026] The steam collection pipe, located above the cooling module, is used to collect the gaseous cooling material that has evaporated after cooling the target device. The steam collection pipe utilizes the physical property of hot steam flowing upward naturally, which greatly reduces the resistance of steam flow and can collect steam without the need for an additional high-power fan. At the same time, it collects steam from multiple dispersed heat sources such as generators, converters, and transformers in a unified manner, realizing integrated thermal management at the whole machine level and avoiding the problems of complex piping and difficult maintenance caused by independent cooling systems for each component.

[0027] The condenser, located above the steam manifold, condenses the gaseous cooling material into a liquid state using sea breeze. Positioning the condenser at the highest point of the system utilizes natural sea breeze for condensation, eliminating the need for additional cooling fans and significantly reducing parasitic energy consumption while improving the unit's net power generation efficiency. Furthermore, its location above the nacelle prevents the direct introduction of salty sea breeze into the nacelle, protecting the delicate electrical equipment from corrosion. The condenser can be installed on the windward side of the nacelle top, employing a tube-fin structure. Both the heat exchange tubes and fins are made of marine corrosion-resistant materials, meeting the highest marine corrosion protection standards. The condenser's air inlet is located at the bottom, connected to the steam manifold outlet, while the liquid outlet is located at the top, connected to the condensate gravity return pipeline inlet. Utilizing natural sea breeze for condensation of the gaseous cooling material further reduces parasitic energy consumption by eliminating the need for additional cooling fans.

[0028] The return pipe, connected between the condenser and the storage tank, is used to transfer the liquid cooling material in the condenser to the storage tank. Since the condenser is located at the highest point and the storage tank is located at the lower point, the liquid cooling material can automatically flow back to the storage tank by gravity, eliminating the dependence on the return pump in the traditional water cooling system. This not only saves energy but also eliminates a potential point of mechanical failure, achieving maintenance-free operation.

[0029] This invention utilizes the unique natural sea breeze and gravitational potential energy of offshore wind power as the driving force, replacing the high-energy-consuming cooling fans and return pumps in traditional cooling systems. By leveraging the latent heat of phase change from nucleation boiling of the cooling material, the heat transfer coefficient is an order of magnitude higher than that of traditional single-phase water cooling. Only a minimal proportion of the mass flow rate required by traditional water cooling is needed to achieve higher heat dissipation, making it suitable for the high heat flux density cooling requirements of 15MW+ ultra-large units. Assisted by the buoyancy generated by the evaporation of the cooling material, the condensate flows back to the storage tank by gravity. Only a low-power auxiliary circulation pump is needed to maintain system pressure and flow balance. The circulation pump power is far lower than that of traditional water cooling systems, significantly reducing the unit's self-consumption of electricity and improving the unit's power generation efficiency. The nucleation boiling process occurs at a constant saturation temperature, which can control the operating temperature difference of core components such as the generator stator and switching chip modules within a very small range, significantly lower than traditional water cooling. This significantly reduces the impact of thermal stress fatigue on device lifespan and greatly extends the service life of the switching chip modules, stator winding insulation, and permanent magnets. High-efficiency phase change cooling allows generators to operate at higher current densities, significantly reducing the generator's structural volume and weight. The weight reduction of the nacelle directly reduces the structural load and manufacturing cost of the tower and foundation. Combined with improved power generation efficiency, extended lifespan of core components, and reduced operation and maintenance costs, it can significantly optimize the unit's cost per kilowatt-hour throughout its entire life cycle.

[0030] In one embodiment, such as Figure 1 As shown, the target device includes a generator 17, and the cooling module 13 includes a generator cooling unit. (Refer to...) Figure 2 The diagram shows a structural block diagram of a generator cooling unit according to an embodiment of the present invention. The generator cooling unit has an annular cavity, in which the stator 21 of the generator is sealed and filled with liquid cooling material. An air gap is included between the stator 21 and the rotor 22 of the generator, and a cooling wall is formed on the side of the annular cavity near the air gap. The generator cooling unit is used to cool the stator 21 of the generator through the liquid cooling material in the annular cavity. During the rotation of the rotor 22 of the generator around the main shaft 23, the heat generated by the eddy currents excited in the air gap by the cooling wall is cooled.

[0031] In this embodiment of the invention, a dedicated cooling structure for a generator inside a wind turbine nacelle is provided. Its core lies in constructing a thermal management system that separates static and dynamic components and facilitates indirect heat transfer. Specifically, the generator stator (stationary component) is entirely sealed within an annular cavity, which constitutes the main body of the generator cooling unit. The cavity is filled with an insulating liquid cooling material (such as electronic fluorinated liquid), ensuring that the stator core and windings are completely immersed in the coolant and in direct contact with the liquid working fluid.

[0032] A necessary air gap is maintained between the stator and the rotor (rotating components). The inner wall of this annular cavity (i.e., the side closest to the air gap) is designed as a cooling wall, which serves as both a container wall for holding the liquid working fluid and a physical barrier to isolate the coolant from the rotor air gap.

[0033] During operation, this cooling unit dissipates heat through a dual mechanism: On the stator side, the liquid cooling material directly absorbs the Joule heat and iron loss heat generated by the stator, undergoing a phase change (boiling) or carrying away heat through forced convection. On the rotor side, when the generator rotor rotates at high speed, Taylor-Couette eddies are generated in the air gap using aerodynamic principles. These eddies act as fluid thermal bridges, efficiently transferring the heat generated by the rotor (such as wind wear loss and eddy current loss) to the cooling walls. After passing through the walls, the heat is immediately absorbed and carried away by the liquid cooling material inside the cavity.

[0034] In this embodiment of the invention, no coolant needs to be introduced into the rotor; the rotating components are completely physically isolated from the coolant through an "air gap + wall" structure. This means that the rotating shaft seal and rotary joint are completely eliminated, fundamentally preventing the possibility of coolant leakage into the generator or polluting the environment, greatly improving the operational reliability of the unit in harsh marine environments. The stator is directly immersed in the phase change coolant, utilizing nucleus boiling heat transfer, whose heat transfer coefficient is thousands of times that of traditional air cooling and tens of times that of traditional water cooling (sensible heat transfer). It can quickly remove the high-density heat from the stator windings and core. Furthermore, since the boiling process takes place at a constant saturation temperature, the overall temperature distribution of the stator is extremely uniform, effectively eliminating local hot spots, significantly reducing the aging effect of thermal stress on the insulation material, and extending the generator's lifespan. The eddy current effect excited by rotor rotation is used as the active heat transfer medium. Under high-speed rotation, the air in the air gap will form a regular vortex structure. In this embodiment of the invention, the vortex effect excited by the rotor rotation is used as an active heat transfer medium. Without additional energy consumption, the rotor heat can be efficiently "pumped" to the cooling wall, realizing efficient indirect cooling of the rotor and solving the problem of difficult heat dissipation of the rotor of the closed generator.

[0035] Reference Figure 3 The diagram shows a cross-sectional view of the generator cooling unit according to an embodiment of the present invention. A steam collecting drum 31 is provided at the top of the annular cavity, and the steam collecting drum outlet 32 ​​is connected to the steam collecting pipe 14. The liquid inlet 33 of the annular cavity is located at the bottom and is connected to the flow controller 12. The generator stator 21 is completely sealed in the annular cavity formed by the outer casing and the non-magnetic isolation sleeve on the air gap side. During the rotation of the generator rotor 22 around the main shaft 23, Taylor-Couette eddy currents are generated in the air gap between the generator stator 21 and the generator rotor 22. The heat generated by the eddy current loss and wind friction loss of the generator rotor 22 is transferred across the air gap to the cooling wall on the stator 21 side of the generator through air convection heat transfer, and is finally carried away by the cooling material.

[0036] The present invention adopts a composite scheme of stator full immersion phase change cooling jacket and rotor air gap eddy current indirect cooling to achieve efficient isothermal cooling of stator while completing rotor cooling in a way that is liquid-free and without dynamic seals, thus avoiding the fatal hidden danger of rotor liquid cooling dynamic seal leakage from the physical source.

[0037] In one embodiment, such as Figure 1 As shown, the target device includes a converter 18, and the cooling module 13 includes a converter cooling unit. (Refer to...) Figure 4 The diagram shows a structural block diagram of a converter cooling unit according to an embodiment of the present invention. The converter cooling unit includes a plurality of vertically arranged heat exchange fins, each heat exchange fin having a sealed cavity filled with liquid cooling material. The converter is in contact with the outer surface of the heat exchange fins. The converter cooling unit is used to cool the converter through the liquid cooling material in the sealed cavity.

[0038] In this embodiment of the invention, a heat dissipation device specifically designed for converters within wind turbine nacelles is provided. Its core lies in constructing a phase-change heat transfer interface with an external heat source and internal cooling material. Specifically, the main body of the converter cooling unit is a hollow, sealed cavity (i.e., a cold plate). Inside the cold plate is a sealed cavity with vertically arranged enhanced heat exchange fins. A transverse liquid inlet distribution cavity is located at the bottom of the cold plate, connected to the outlet of a branch flow controller. A transverse gas outlet collection cavity is located at the top of the cold plate, connected to a steam collection pipe. The cavity is filled with a fixed amount of insulating liquid cooling material (such as electronic fluorinated liquid). The filling amount is precisely calculated to ensure a stable gas-liquid two-phase coexistence zone is formed within the cavity during operation. To enhance internal heat exchange, multiple heat exchange fins are arranged vertically within the sealed cavity. These fins not only increase the contact area with the internal working fluid but also form multiple vertical, narrow flow channels.

[0039] In terms of thermal connection, the core heat-generating components of the converter, such as the IGBT (Insulated Gate Bipolar Transistor) power module, are tightly attached to the outer surface of the heat exchange fins / cold plate through a thermally conductive interface material. During operation, the heat generated by the IGBT is conducted through the outer wall of the cold plate to the interior. The liquid cooling material inside the sealed cavity absorbs heat and rapidly boils and evaporates (nuclear boiling), utilizing the latent heat of phase change to quickly transfer the heat to the circulation loop at the top of the cavity.

[0040] This invention utilizes the latent heat of phase change in the cooling material for heat absorption, with a heat transfer coefficient 1-2 orders of magnitude higher than traditional sensible heat transfer (such as simple water cooling or air cooling). This means that a large amount of heat can be removed even with a very small temperature difference, rapidly mitigating transient thermal shocks caused by frequent switching of IGBTs, effectively reducing junction temperature fluctuations, and extending the fatigue life of the power module. The vertical fin design greatly expands the heat exchange area within a limited volume, resulting in a very compact cooling unit structure. Furthermore, since converter modules are typically vertically mounted, this cooling unit can be designed as a back-mounted or surface-mounted module. When an IGBT module fails, it can be independently disassembled and replaced without draining the entire system's coolant (using quick-connect couplings), significantly reducing the difficulty and cost of offshore maintenance.

[0041] In one embodiment, such as Figure 1 As shown, the target device includes a gearbox 19 and a transformer 110, and the cooling module 13 includes a first oil-medium cooling unit 111 and a second oil-medium cooling unit 112. (Refer to...) Figure 5 The diagram shows a structural block diagram of an oil medium cooling unit according to an embodiment of the present invention. A first oil medium cooling unit 111 and a second oil medium cooling unit 112 have a sealed housing filled with liquid cooling material. The sealed housing is provided with a heat exchange channel. A gearbox 19 is connected to the heat exchange channel of the first oil medium cooling unit 111, and a transformer 110 is connected to the heat exchange channel of the second oil medium cooling unit 112. The first oil medium cooling unit 111 is used to cool the lubricating oil in the heat exchange channel of the gearbox 19 through the liquid cooling material in the sealed housing when the lubricating oil flows in the heat exchange channel. The second oil medium cooling unit 112 is used to cool the lubricating oil in the heat exchange channel of the transformer 110 through the liquid cooling material inside the sealed housing when the lubricating oil flows in the heat exchange channel.

[0042] In this embodiment of the invention, a dedicated cooling architecture for gearboxes and transformers within wind turbine nacelles is provided. Its core lies in constructing an isolated heat exchange system with "internal oil circulation and external immersion of cooling materials." Specifically, the cooling module comprises two independent units: a first oil-medium cooling unit for cooling the gearbox lubricating oil and a second oil-medium cooling unit for cooling the transformer insulating oil. The main structure of both units is a sealed shell filled with liquid cooling material (such as electronic fluorinated liquid), which directly serves as a phase-change heat absorption chamber. The shell can be made of marine-resistant stainless steel. Inside the shell is a plate-type heat exchange core, formed by welding multiple sets of parallel stainless steel plates to create independent oil-medium flow channels. The entire plate-type heat exchange core is completely immersed in the cooling material on the shell side. An outlet is located at the top of the shell, connected to a steam collection pipe; an inlet is located at the bottom, connected to the outlet of a flow controller; and oil inlets and outlets are located on the sides of the shell, connected to the oil circulation pipelines of the gearbox and transformer, respectively.

[0043] Inside the casing, a dedicated heat exchange channel (usually a plate or tubular structure) is designed. The gearbox's lubricating oil circuit and the transformer's insulating oil circuit are respectively connected to the corresponding heat exchange channel, allowing the hot oil to flow within the channel. During operation, the high-temperature lubricating oil or insulating oil exchanges heat with the liquid cooling material inside the sealed casing through the tube walls / plates within the heat exchange channel. After absorbing heat, the cooling material inside the casing undergoes a boiling phase change, rapidly carrying away the heat from the oil using the enormous latent heat of phase change. This design ensures that the "oil" and the "cooling material" are physically completely isolated, never coming into contact, with heat transferred only through the solid wall surface, while the cooling medium carries the heat out of the system through boiling evaporation within the casing.

[0044] This invention utilizes the latent heat of phase change of the cooling material within a sealed casing for heat absorption. Since the phase change process occurs at a constant temperature (saturation temperature) and has a large latent heat value, the oil-medium cooling unit can rapidly absorb the large amount of heat generated instantaneously by the oil without significantly increasing its own temperature. This effectively mitigates oil temperature fluctuations and prevents thermal stress damage to the gearbox and transformer due to overheating or excessive temperature differences.

[0045] In one embodiment, the flow controller 12 includes a proportional regulating valve; the flow controller 12 is used to acquire the temperature and pressure of the target device; and adjust the opening of the proportional regulating valve according to the temperature and pressure of the target device to regulate the flow rate of the liquid cooling material output from the storage tank 11.

[0046] In this embodiment of the invention, the flow controller is configured to have multi-parameter acquisition and processing capabilities, and can acquire in real time the temperature signals of key nodes (such as generator stator, converter IGBT, gearbox oil temperature, etc.) in the wind turbine nacelle and the pressure signals inside the cooling circuit system.

[0047] The flow controller can use an electric proportional regulating valve. The valve body material is compatible with the cooling material. It can adjust the branch opening in real time according to the operating status of the corresponding cooling unit to control the liquid inlet flow rate, ensuring that the working fluid in each unit is always in a stable nucleation boiling range, and avoiding local drying due to insufficient flow or boiling failure due to excessive flow.

[0048] During operation, the control algorithm inside the flow controller calculates the optimal cooling flow rate required under the current operating conditions based on the collected temperature and pressure data. Subsequently, the controller outputs a corresponding electrical signal to drive the proportional control valve, continuously and linearly adjusting its opening between 0% and 100%. When an increase in engine compartment temperature or abnormal system pressure is detected, the controller instructs the valve to increase its opening, increasing the output flow rate of the liquid coolant and enhancing heat exchange. When the temperature decreases or the system is under low load, the controller instructs the valve to decrease its opening, maintaining the minimum necessary flow rate. This adjustment method achieves on-demand allocation and precise supply of the cooling fluid flow rate, ensuring that the system always operates in its optimal thermodynamic state.

[0049] In one embodiment, the flow controller 12 includes a circulation pump with a filter element at the inlet and a check element at the outlet; the flow controller 12 is used to transfer liquid cooling material in the condenser 15 to the storage tank 11 through the circulation pump auxiliary return pipe 16.

[0050] In this embodiment of the invention, the flow controller also integrates a circulating pump as a power source to provide the pressure head required for fluid delivery. A filter element (such as a Y-type filter or screen) is connected in series at the inlet of the circulating pump to intercept impurities in the fluid; a check element (such as a one-way valve or check valve) is connected in series at the outlet of the circulating pump to restrict the flow direction of the fluid. The circulating pump is a shielded magnetic pump, made of materials compatible with cooling materials, with a redundant arrangement of one pump in operation and one on standby. A filter element is installed at the pump inlet, and a check element and pressure monitoring element are installed at the outlet to ensure system reliability.

[0051] During operation, the flow controller activates the circulating pump, generating suction and thrust to assist or actively transport the condensed liquid cooling material from the condenser back to the storage tank along the return pipeline. Before entering the pump body, the liquid cooling material passes through a filter element, where metal debris, sealing residue, or solid particles are trapped, allowing only clean liquid to enter the pump chamber. When the pump stops working or the system pressure fluctuates, the check valve at the outlet automatically closes, physically blocking the pipeline and preventing backflow of liquid from the storage tank or subsequent pipelines from impacting the pump body.

[0052] In one embodiment, the steam manifold 14 is provided with a continuous upward angle along the flow direction of the gaseous cooling material.

[0053] In this embodiment of the invention, the steam collection pipe can be made of seamless stainless steel pipe resistant to marine corrosion. The pipe is set with a continuous upward angle along the steam flow direction, without U-shaped liquid accumulation bends or downward concave sections, to avoid air resistance caused by liquid accumulation in the pipe. The pipe is arranged along the main beam at the top of the nacelle, and the air outlet of each cooling unit is connected to the main pipe through a branch pipe.

[0054] As a common channel connecting the various cooling modules and the condenser, the steam manifold is not installed horizontally or arbitrarily, but strictly follows the principle of "continuously rising along the flow direction". From the inlet (near the cooling module end) to the outlet (near the condenser end) of the steam manifold, the pipeline shows a continuous upward trend in vertical height, forming a monotonously rising diagonal line at the bottom of the pipeline, eliminating any local concave or "U-shaped" bends.

[0055] The continuously upward-facing layout conforms to the natural upward flow of steam. This streamlined design ensures smooth and unobstructed steam flow, minimizing friction resistance. This not only increases the steam transfer speed but also reduces the system's power requirement for the auxiliary circulation pump, thereby improving the overall reflux efficiency of the phase change cycle.

[0056] In one embodiment, the return pipe 16 is inclined at a downward angle along the flow direction of the liquid cooling material in the condenser 15.

[0057] In this embodiment of the invention, the return pipeline can be made of seamless stainless steel pipe. The pipeline is set with a downward angle along the direction of condensate flow to ensure that the condensate flows back to the collection tank stably by gravity, without any upward climbing section, thus avoiding liquid accumulation and air blockage.

[0058] The return pipe connects the outlet of the external air-cooled condenser to the storage tank inside the engine room. The piping is laid strictly according to the principle of "continuous downward slope along the flow direction." That is, from the condenser outlet to the storage tank inlet, the pipe exhibits a continuous downward trend in vertical height, forming a monotonically descending slope at the bottom, eliminating any localized bulges (air pockets) or horizontal stagnation sections.

[0059] The continuously downward-sloping design fully utilizes the potential energy difference between the condenser (high position) and the storage tank (low position). The liquid cooling material automatically slides back into the storage tank under the action of gravity. This gravity-driven mechanism reduces the power consumption of the circulation pump during the reflux process, and can even achieve completely passive reflux under certain operating conditions, greatly reducing the parasitic energy consumption of the system.

[0060] In one embodiment, the cooling material is an electronic fluorinated liquid.

[0061] In this embodiment of the invention, the electronic fluorinated liquid is a colorless, odorless, and transparent perfluorocarbon compound or hydrofluoroether liquid (such as perfluoropolyether, hydrofluoroether, etc.). Chemically, it has extremely high chemical inertness and a stable molecular structure; physically, it has extremely low surface tension (typically <20 dyn / cm) and low kinematic viscosity (close to water), which gives it excellent wettability and permeability, enabling it to penetrate into tiny gaps.

[0062] In terms of thermodynamic properties, this cooling material has a suitable boiling point (e.g., adjustable between 30°C and 60°C) and can undergo a phase transition at the heating temperatures of electronic devices. Simultaneously, it possesses extremely high dielectric strength (breakdown voltage > 30kV) and extremely low dielectric constant, making it an ideal electrical insulator. Furthermore, this material is non-flammable, has no flash point, and exhibits excellent environmental characteristics.

[0063] The complete system operation flow of this invention embodiment is as follows: During unit startup, the auxiliary circulating pump starts, pressurizing and delivering the liquid working fluid from the cooling material collection tank to the flow control devices on each branch. The flow control devices supply the working fluid to each cooling unit according to a preset opening. Once the working fluid fills the cavity of each unit, the unit begins grid connection and load increase. When the unit enters normal operating conditions, the heat generated by each heat-generating component is transferred to the cooling material in the corresponding cooling unit. The working fluid undergoes stable nucleus boiling at saturation temperature, evaporating from liquid to gas, absorbing heat using the latent heat of phase change to achieve isothermal cooling of each component. The gaseous working fluid generated by each cooling unit flows upward into the steam collection main pipe and is uniformly delivered to the air-cooled condenser at the top of the nacelle. In the condenser, the gaseous working fluid exchanges heat with the natural sea breeze, releasing latent heat and condensing into a liquid state. The condensed liquid working fluid then flows back to the cooling material collection tank by gravity along the condensate gravity return pipeline, completing a complete closed-loop cycle. When the unit load fluctuates, the flow control devices of each branch automatically adjust the branch opening and dynamically adjust the liquid inlet flow based on the real-time feedback signals of the operating temperature and pressure of the corresponding cooling unit, ensuring that the working fluid in each unit is always in a stable nucleus boiling range and avoiding boiling runaway caused by sudden load changes. When the system pressure exceeds the set threshold, the safety protection element of the collection tank automatically opens to release pressure, ensuring the safe operation of the system. A complete cycle of "differentiated phase change heat absorption in the engine room - condensation by sea breeze outside the engine room" has been constructed. A dedicated phase change cooling scheme has been designed for the characteristics of different heat sources in the engine room, solving the industry problems of unsystematic phase change cooling of single components and interference from multiple heat sources in existing technologies.

[0064] The embodiments of the present invention have the following beneficial effects: 1. A leap in heat exchange efficiency: By utilizing the latent heat of phase change through nucleation boiling of the working fluid, the heat transfer coefficient is increased by an order of magnitude compared to traditional single-phase water cooling. Only a very small proportion of the working fluid mass flow rate required by traditional water cooling is needed to achieve higher heat dissipation, perfectly meeting the high heat flux density heat dissipation requirements of 15MW+ ultra-large units.

[0065] 2. Significantly reduced pumping parasitic energy consumption: The system relies on the buoyancy generated by the evaporation of the working fluid to assist the flow of the working fluid, and the condensate flows back to the storage tank by gravity. Only a low-power auxiliary circulation pump is needed to maintain the system pressure and flow balance. The power of the circulation pump is much lower than that of the traditional water-cooled system, which greatly reduces the self-consumption of the unit and improves the power generation efficiency of the unit.

[0066] 3. Excellent isothermal characteristics and significantly extended lifespan of core components: The nucleation boiling process is carried out at a constant saturation temperature, which can control the operating temperature difference of core components such as generator stator and IGBT module within a very small range. This is significantly lower than traditional water cooling, greatly reducing the impact of thermal stress fatigue on device lifespan and significantly extending the service life of IGBT module, stator winding insulation, and permanent magnet.

[0067] 4. Comprehensive improvement in intrinsic safety level: The system uses highly insulating, non-flammable electronic fluorinated liquid as the cooling material, so even if a small amount of leakage occurs, it will not cause electrical short circuits or explosions; the generator rotor has a non-dynamic seal design, which completely avoids the risk of leakage from rotor liquid cooling; the whole system is closed-loop, with no external air introduced, which solves the problem of salt spray corrosion at sea from the root and perfectly meets the long-term service requirements of the harsh marine environment.

[0068] 5. Significantly reduced operation and maintenance difficulty and cost: The converter adopts a surface-mounted cold plate design to achieve complete isolation between electrical and fluid circuits, supporting on-site non-destructive replacement of power modules with liquid, without the need to stop the machine to drain the working fluid; the only moving part of the system is the low-power auxiliary circulation pump, which greatly reduces the number of failure points, significantly improves reliability, and greatly reduces the high cost of operation and maintenance frequency of deep-sea units.

[0069] 6. Optimization of levelized cost of electricity throughout the entire life cycle: Efficient phase change cooling allows the generator to operate at higher current densities, which can significantly reduce the generator's structural volume and weight. The weight reduction of the nacelle directly reduces the structural load and manufacturing cost of the tower and foundation. Combined with improved power generation efficiency, extended lifespan of core components, and reduced operation and maintenance costs, the levelized cost of electricity throughout the entire life cycle of the unit can be significantly optimized.

[0070] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims, and all of these forms are within the protection scope of the present invention.

Claims

1. An offshore wind turbine nacelle cooling system, characterized in that, include: Storage tanks are used to store liquid cooling materials. A flow controller, located above the storage tank, is used to regulate the flow rate of the liquid cooling material output from the storage tank; A cooling module is located above the flow controller and in contact with the target device inside the wind turbine nacelle. It is used to cool the target device using the liquid cooling material output from the storage tank. A vapor collection pipe, located above the cooling module, is used to collect the vaporized cooling material that has evaporated into a gaseous state after cooling the target device. A condenser, located above the steam collecting pipe, is used to condense the gaseous cooling material into a liquid cooling material by means of sea breeze; A return pipe, connected between the condenser and the storage tank, is used to transfer the liquid cooling material in the condenser to the storage tank.

2. Offshore wind turbine platform cooling system according to claim 1, characterized in that The target device includes a generator, and the cooling module includes a generator cooling unit; the generator cooling unit has an annular cavity, the stator of the generator is sealed in the annular cavity, and the annular cavity is filled with the liquid cooling material; an air gap is included between the stator and rotor of the generator, and a cooling wall is formed on the side of the annular cavity near the air gap; The generator cooling unit is used to cool the stator of the generator through the liquid cooling material in the annular cavity; during the rotation of the generator rotor, the cooling wall surface cools the heat generated by the eddy currents excited in the air gap of the generator rotor.

3. Offshore wind turbine platform cooling system according to claim 2, characterized in that A steam collecting chamber is provided at the top of the annular cavity, and the outlet of the steam collecting chamber is connected to the steam collecting pipe; the liquid inlet of the annular cavity is located at the bottom and is connected to the flow controller.

4. Offshore wind turbine platform cooling system according to claim 1, characterized in that The target device includes a converter, and the cooling module includes a converter cooling unit; the converter cooling unit includes a plurality of vertically arranged heat exchange fins, each heat exchange fin having a sealed cavity filled with the liquid cooling material; the converter is in contact with the outer surface of the heat exchange fins. The converter cooling unit is used to cool the converter using liquid cooling material in the sealed cavity.

5. Offshore wind turbine platform cooling system according to claim 1, characterized in that, The target device includes a gearbox and a transformer. The cooling module includes a first oil medium cooling unit and a second oil medium cooling unit. The first oil medium cooling unit and the second oil medium cooling unit have a sealed shell, which is filled with the liquid cooling material. The sealed shell is provided with a heat exchange channel. The gearbox is connected to the heat exchange channel of the first oil medium cooling unit, and the transformer is connected to the heat exchange channel of the second oil medium cooling unit. The first oil medium cooling unit is used to cool the lubricating oil in the heat exchange channel through the liquid cooling material of the sealed shell when the lubricating oil of the gearbox flows in the heat exchange channel; The second oil medium cooling unit is used to cool the lubricating oil in the heat exchange channel by means of liquid cooling material inside the sealed housing when the lubricating oil of the transformer flows in the heat exchange channel.

6. Offshore wind turbine platform cooling system according to claim 1, characterized in that The flow controller includes a proportional regulating valve; The flow controller is used to acquire the temperature and pressure of the target device; and adjust the opening of the proportional control valve according to the temperature and pressure of the target device to adjust the flow rate of the liquid cooling material output from the storage tank.

7. Offshore wind turbine platform cooling system according to claim 1, characterized in that The flow controller includes a circulating pump, the inlet of which is equipped with a filter element, and the outlet of which is equipped with a check element; The flow controller is used to assist the reflux pipe in transferring the liquid cooling material in the condenser to the storage tank via the circulation pump.

8. Offshore wind turbine platform cooling system according to claim 1, characterized in that The steam collecting pipe is set with a continuous upward angle along the flow direction of the gaseous cooling material.

9. Offshore wind turbine platform cooling system according to claim 1, characterized in that The return pipe is inclined downwards along the flow direction of the liquid cooling material in the condenser.

10. Offshore wind turbine platform cooling system according to claim 1, characterized in that The cooling material is an electronic fluorinated liquid.

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