Micro-channel liquid cooling system for wide-temperature-range stack and control method thereof

Abstract

The application discloses a kind of microchannel liquid cooling systems and control method for wide temperature range electric pile, the control method includes: receiving real-time acquisition electric pile temperature;Whether the electric pile temperature is ≥ set threshold by controller judging;If not, control three-way switch valve to switch on bypass branch, liquid high-pressure pump is operated at low frequency, executes single-phase sensible heat cooling;If yes, control three-way switch valve switches to atomizing nozzle branch, liquid high-pressure pump is operated at high frequency, makes cooling liquid atomization and enters microchannel radiating cooling plate, utilizes latent heat of phase change to radiate, executes local phase change cooling;Its beneficial effect is: the present application is by using double branch structure and intelligent switching mechanism, single-phase sensible heat cooling is used at low temperature to save energy, automatically switches to microchannel local phase change cooling at high temperature to strengthen heat dissipation, intelligently realizes the cooling intensity of on-demand regulation, and cooling working substance adapts wide temperature range demand.

Description

Technical Field

[0001] This invention relates to the field of thermal management technology, specifically to a microchannel liquid cooling system and control method for a wide-temperature-range fuel cell stack. Background Technology

[0002] With the development of hydrogen energy and new energy technologies, fuel cell stacks and electrolyzers need to operate stably within a wide temperature range of -30℃ to 120℃. Traditional liquid cooling systems use a single-phase circulation of ethylene glycol aqueous solution, which is safe and low-cost, but has insufficient heat dissipation capacity under high power density conditions (e.g., >1.5W / cm²), easily leading to local overheating. On the other hand, phase change cooling systems using refrigerants (such as R134a) have high heat exchange efficiency, but have problems such as the risk of working fluid flammability, high GWP value, difficulty in low-temperature start-up, system complexity, and high energy consumption.

[0003] Furthermore, existing liquid cooling systems mostly operate in a fixed mode, unable to dynamically adjust the cooling intensity according to the fuel cell stack's heat load. This results in energy waste under low loads and insufficient heat dissipation under high loads. Therefore, there is an urgent need for a cooling solution that combines wide temperature range adaptability, high safety, on-demand energy saving, and efficient heat dissipation capabilities. Summary of the Invention

[0004] In view of the technical defects mentioned in the background art, the purpose of this invention is to provide a microchannel liquid cooling system and control method for wide temperature range fuel cell stacks, aiming to at least partially solve one of the technical problems in the related art.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a microchannel liquid cooling system for wide-temperature-range fuel cell stacks, the system comprising:

[0006] A liquid storage tank is used to hold a cooling medium.

[0007] A high-pressure liquid pump, the inlet of which is connected to the liquid storage tank, is used for the delivery of the cooling working fluid;

[0008] The first pressure sensor is located at the pump outlet and is used to monitor the pump outlet pressure in real time.

[0009] A three-way switching valve has its inlet connected to the outlet of the liquid high-pressure pump, and its two outlets connected to a bypass branch and an atomizing nozzle branch, respectively; wherein, the bypass branch is directly connected to the fuel cell stack cooling inlet.

[0010] The atomizing nozzle branch includes an atomizing nozzle and a microchannel heat dissipation cooling plate in sequence; the microchannel heat dissipation cooling plate is integrated inside the fuel cell stack or closely attached to the heating surface of the fuel cell stack, and meets the technical parameter requirements of the fuel cell stack for bipolar plates;

[0011] Temperature sensors, located on the surface of the fuel cell stack or at the cooling inlet / outlet, are used to monitor the fuel cell stack temperature in real time;

[0012] The second pressure sensor is located at the fuel cell stack cooling inlet and is used to monitor the fuel cell stack inlet pressure in real time.

[0013] A gas-liquid separator, the inlet of which is connected to the fuel cell stack cooling outlet, is used to separate air bubbles in the coolant;

[0014] The radiator has its inlet connected to the outlet of the gas-liquid separator, and its outlet flows back to the liquid storage tank.

[0015] The controller is electrically connected to the first pressure sensor, the second pressure sensor, the temperature sensor, the high-pressure liquid pump, and the three-way switching valve, and is configured as follows:

[0016] When the fuel cell stack temperature is less than the set threshold, the three-way switching valve is controlled to open the bypass branch and the speed of the liquid high-pressure pump is reduced to perform single-phase sensible heat cooling.

[0017] When the fuel cell stack temperature is greater than or equal to a set threshold, the three-way switching valve is controlled to switch to the atomizing nozzle branch, and the speed of the liquid high-pressure pump is increased, so that the coolant is sprayed into the microchannel heat dissipation cooling plate through the atomizing nozzle. Flash boiling occurs in the local low-pressure area, and heat is efficiently absorbed by utilizing the latent heat of vaporization to perform local phase change cooling.

[0018] As one specific implementation of this application, the cooling medium is an aqueous solution of ethylene glycol, the volume concentration of the aqueous solution of ethylene glycol is 50%, the freezing point is not higher than -35℃, and the boiling point is not lower than 120℃ under system pressure.

[0019] As a specific implementation of this application, the inner wall of the microchannel heat dissipation cooling plate is provided with a hydrophilic microstructure or a hydrophilic coating to increase the critical heat flux density and prevent drying.

[0020] As a preferred implementation of this application, the liquid storage tank is further equipped with an electric heating preheating device, which is used to preheat the cooling working fluid when the ambient temperature is ≤ a preset temperature.

[0021] As one specific implementation of this application, the gas-liquid separator is provided with an exhaust valve at the top for discharging non-condensable gases from the system.

[0022] Secondly, the present invention also provides a control method for a microchannel liquid cooling system for a wide-temperature-range fuel cell stack, applied to the microchannel liquid cooling system for a wide-temperature-range fuel cell stack described in the first aspect, the control method comprising:

[0023] Receives real-time data on the fuel cell stack temperature;

[0024] The controller determines whether the temperature of the fuel cell stack is greater than or equal to a set threshold.

[0025] If not, the three-way switching valve is controlled to open the bypass branch, and the liquid high-pressure pump operates at low frequency to perform single-phase sensible heat cooling.

[0026] If so, the three-way switching valve is switched to the atomizing nozzle branch, and the liquid high-pressure pump runs at high frequency, so that the coolant is atomized and enters the microchannel heat dissipation cooling plate, and heat dissipation is performed by utilizing the latent heat of phase change.

[0027] As a preferred implementation of this application, the method further includes:

[0028] When the ambient temperature is less than or equal to the preset temperature, the cooling medium is preheated by an electric heating preheating device deployed inside the storage tank.

[0029] As a preferred implementation of this application, the method further includes:

[0030] The controller adjusts the speed of the high-pressure liquid pump based on the real-time monitored pressure value to maintain pressure stability.

[0031] The technical solution provided by the embodiments of the present invention adopts a dual-branch structure and an intelligent switching mechanism. When the fuel cell stack is at a low temperature, it uses single-phase sensible heat cooling to save energy. When the fuel cell stack is at a high temperature, it automatically switches to microchannel local phase change cooling to enhance heat dissipation. It intelligently realizes the adjustment of cooling intensity as needed, and the cooling working fluid is adapted to the wide temperature range requirements, thereby taking into account wide temperature range adaptability, energy efficiency, safety and thermal performance. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the specific embodiments or the prior art will be briefly introduced below.

[0033] Figure 1 This is a schematic diagram of a microchannel liquid cooling system for a wide temperature range fuel cell stack provided in an embodiment of the present invention;

[0034] Figure 2 This is a flowchart of a control method for a microchannel liquid cooling system for a wide temperature range fuel cell stack provided in an embodiment of the present invention.

[0035] The annotations in the attached figures are explained as follows:

[0036] 1. Heated liquid storage tank; 2. High-pressure liquid pump; 3. Three-way switching valve; 4. Atomizing nozzle; 5. Microchannel heat dissipation cooling plate; 6. Gas-liquid separator with exhaust function; 7. Radiator; 8. Controller; 9. Post-pump pressure sensor; 10. Reactor feed temperature sensor; 11. Reactor feed pressure sensor; 12. Reactor discharge temperature sensor. Detailed Implementation

[0037] 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.

[0038] It should be understood that, when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, integrals, steps, operations, elements and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components and / or collections thereof.

[0039] Throughout this specification, references to "an embodiment," "an example," or "an example" mean that a particular feature, structure, or characteristic described in connection with that embodiment or example is included in at least one embodiment of the invention. Therefore, the phrases "in an embodiment," "in an embodiment," "an example," or "an example" appearing in various places throughout the specification do not necessarily refer to the same embodiment or example. Furthermore, specific features, structures, or characteristics can be combined in one or more embodiments or examples in any suitable combination and / or sub-combination.

[0040] It should be noted that, unless otherwise stated, the technical terms used in this embodiment have the common meaning as understood in the relevant technical field.

[0041] Please refer to Figure 1 This invention provides a microchannel liquid cooling system for a wide-temperature-range fuel cell stack, the system comprising:

[0042] Storage tank 1 is used to contain the cooling working fluid;

[0043] A high-pressure liquid pump 2, the inlet of which is connected to the liquid storage tank 1, is used for the delivery of the cooling working fluid;

[0044] The first pressure sensor 9 is located at the pump outlet and is used to monitor the pump outlet pressure in real time.

[0045] The three-way switching valve 3 has its inlet connected to the outlet of the liquid high-pressure pump 2, and its two outlets connected to the bypass branch and the atomizing nozzle branch, respectively; wherein, the bypass branch is directly connected to the fuel cell stack cooling inlet.

[0046] The atomizing nozzle branch includes an atomizing nozzle 4 and a microchannel heat dissipation cooling plate 5 in sequence; the microchannel heat dissipation cooling plate 5 is integrated inside the fuel cell stack or closely attached to the heating surface of the fuel cell stack, and meets the technical parameter requirements of the fuel cell stack for bipolar plates.

[0047] Temperature sensors, located on the surface of the fuel cell stack or at the cooling inlet / outlet, are used to monitor the fuel cell stack temperature in real time; in application, they include in-stack temperature sensor 10 and out-of-stack temperature sensor 12.

[0048] The second pressure sensor 11 is located at the fuel cell stack cooling inlet and is used to monitor the fuel cell stack inlet pressure in real time.

[0049] The gas-liquid separator 6 has its inlet connected to the fuel cell stack cooling outlet and is used to separate air bubbles in the coolant;

[0050] Radiator 7, whose inlet is connected to the outlet of the gas-liquid separator 6, and whose outlet flows back to the liquid storage tank 1;

[0051] The controller 8 is electrically connected to the first pressure sensor 9, the second pressure sensor 11, the temperature sensor, the high-pressure liquid pump 2, and the three-way switching valve 3, and is configured as follows:

[0052] When the fuel cell stack temperature is less than the set threshold, the three-way switching valve 3 is controlled to open the bypass branch and the speed of the liquid high-pressure pump 2 is reduced to perform single-phase sensible heat cooling.

[0053] When the temperature of the fuel cell stack is greater than or equal to the set threshold, the three-way switching valve 3 is controlled to switch to the atomizing nozzle branch, and the speed of the liquid high-pressure pump 2 is increased, so that the coolant is sprayed into the microchannel heat dissipation cooling plate 5 through the atomizing nozzle 4, and flash boiling occurs in the local low-pressure area. The latent heat of vaporization is used to efficiently absorb heat and perform local phase change cooling.

[0054] In application, the threshold is taken as 90°C as an example, and the specific value can be customized based on the application scenario; in this embodiment, the technical parameter requirements of the fuel cell stack for the bipolar plate include:

[0055] Thickness < 2mm, thermal conductivity > 15W / (m*k), long-term tolerance to -30-120℃, and long-term stability in high temperature and high humidity environments.

[0056] The cooling medium is an aqueous solution of ethylene glycol, with a volume concentration of 50%, a freezing point not higher than -35°C, and a boiling point not lower than 120°C under system pressure.

[0057] Furthermore, the inner wall of the microchannel heat dissipation cooling plate 5 is provided with a hydrophilic microstructure or a hydrophilic coating to increase the critical heat flux density and prevent drying.

[0058] To ensure cold start reliability, the liquid storage tank 1 is also equipped with an electric heating preheating device, which is used to preheat the cooling working fluid when the ambient temperature is ≤ a preset temperature; the preset temperature can be set to -20℃.

[0059] In this embodiment, the gas-liquid separator 6 is equipped with an exhaust valve at the top to discharge non-condensable gases from the system; and a liquid level sensor is used to monitor the liquid level in real time to avoid insufficient internal coolant.

[0060] The above solution, by adopting a dual-branch structure and intelligent switching mechanism, uses single-phase sensible heat cooling to save energy at low temperatures and automatically switches to microchannel local phase change cooling to enhance heat dissipation at high temperatures. It intelligently adjusts the cooling intensity as needed, and the cooling medium is adapted to a wide temperature range, thus taking into account wide temperature range adaptability, energy efficiency, safety and thermal performance. It is suitable for wide temperature range cooling of fuel cell stacks, electrolyzers or high-power power electronic modules.

[0061] Reference Figure 2 Based on the same inventive concept, this invention also provides a control method for a microchannel liquid cooling system for a wide-temperature-range fuel cell stack, applied to the aforementioned microchannel liquid cooling system for a wide-temperature-range fuel cell stack. The control method includes:

[0062] S101 receives the real-time collected fuel cell stack temperature;

[0063] S102, the controller determines whether the temperature of the fuel cell stack is greater than or equal to a set threshold.

[0064] S103, if not, control the three-way switching valve to open the bypass branch, the liquid high-pressure pump operates at low frequency, and performs single-phase sensible heat cooling;

[0065] S104, if yes, then control the three-way switching valve to switch to the atomizing nozzle branch, the liquid high-pressure pump runs at high frequency, so that the coolant is atomized and enters the microchannel heat dissipation cooling plate, and uses the latent heat of phase change to dissipate heat and perform local phase change cooling.

[0066] The above solution uses the controller as the execution entity, and the devices and connections involved are described in the aforementioned system implementation section.

[0067] Furthermore, the method also includes:

[0068] When the ambient temperature is less than or equal to the preset temperature, the cooling medium is preheated by an electric heating preheating device deployed inside the storage tank.

[0069] Furthermore, the method also includes:

[0070] The controller adjusts the speed of the high-pressure liquid pump based on the real-time monitored pressure value to maintain pressure stability.

[0071] It should be noted that for a more detailed description of the workflow of the method embodiments, please refer to the aforementioned system embodiments section, which will not be repeated here.

[0072] The entire solution employs a dual-branch structure and an intelligent switching mechanism. At low temperatures, it uses single-phase sensible heat cooling to save energy, while at high temperatures, it automatically switches to microchannel local phase change cooling to enhance heat dissipation. It intelligently adjusts the cooling intensity as needed, and the cooling medium is adapted to a wide temperature range, thus combining wide temperature range adaptability, high safety, on-demand energy saving, and efficient heat dissipation capabilities.

[0073] In the embodiments provided in this application, it should be understood that the disclosed methods and systems can also be implemented in other ways. The system embodiments described above are merely illustrative. It should also be noted that in some alternative implementations, the functions marked in the blocks may occur in a different order than those marked in the figures. For example, two consecutive blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagram and / or flowchart, and combinations of blocks in the block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified functions or actions, or using a combination of dedicated hardware and computer instructions.

[0074] Furthermore, the functional modules in the various embodiments of this invention can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part. When using each module, information is collected and stored only with the full authorization of the relevant user or organization and in compliance with relevant laws and regulations, and the security and privacy of the data are protected. Unauthorized access is strictly prohibited. Data processing will be carried out within the scope stipulated by law and will not exceed the authorized purpose and scope. At the same time, the authorizing party has the right to access, correct, delete, restrict processing, refuse, etc., of its personal data, and strictly comply with applicable laws and regulations and conduct compliance reviews.

[0075] If the aforementioned functions are implemented as software functional modules and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or a part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present invention. It should be noted that, in this document, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. The above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention can have various modifications and variations. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

[0076] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in the present invention, and these modifications or substitutions should all be covered within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A microchannel liquid cooling system for a wide-temperature-range fuel cell stack, characterized in that, The system includes: A liquid storage tank is used to hold a cooling medium. A high-pressure liquid pump, the inlet of which is connected to the liquid storage tank, is used for the delivery of the cooling working fluid; The first pressure sensor is located at the pump outlet and is used to monitor the pump outlet pressure in real time. A three-way switching valve has its inlet connected to the outlet of the liquid high-pressure pump, and its two outlets connected to a bypass branch and an atomizing nozzle branch, respectively; wherein, the bypass branch is directly connected to the fuel cell stack cooling inlet. The atomizing nozzle branch includes an atomizing nozzle and a microchannel heat dissipation cooling plate in sequence; the microchannel heat dissipation cooling plate is integrated inside the fuel cell stack or closely attached to the heating surface of the fuel cell stack, and meets the technical parameter requirements of the fuel cell stack for bipolar plates; Temperature sensors, located on the surface of the fuel cell stack or at the cooling inlet / outlet, are used to monitor the fuel cell stack temperature in real time; The second pressure sensor is located at the fuel cell stack cooling inlet and is used to monitor the fuel cell stack inlet pressure in real time. A gas-liquid separator, the inlet of which is connected to the fuel cell stack cooling outlet, is used to separate air bubbles in the coolant; The radiator has its inlet connected to the outlet of the gas-liquid separator, and its outlet flows back to the liquid storage tank. The controller is electrically connected to the first pressure sensor, the second pressure sensor, the temperature sensor, the high-pressure liquid pump, and the three-way switching valve, and is configured as follows: When the fuel cell stack temperature is less than the set threshold, the three-way switching valve is controlled to open the bypass branch and the speed of the liquid high-pressure pump is reduced to perform single-phase sensible heat cooling. When the fuel cell stack temperature is greater than or equal to a set threshold, the three-way switching valve is controlled to switch to the atomizing nozzle branch, and the speed of the liquid high-pressure pump is increased, so that the coolant is sprayed into the microchannel heat dissipation cooling plate through the atomizing nozzle. Flash boiling occurs in the local low-pressure area, and heat is efficiently absorbed by utilizing the latent heat of vaporization to perform local phase change cooling.

2. The microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in claim 1, characterized in that, The cooling medium is an aqueous solution of ethylene glycol, with a volume concentration of 50%, a freezing point not higher than -35°C, and a boiling point not lower than 120°C under system pressure.

3. The microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in claim 1, characterized in that, The inner wall of the microchannel heat dissipation cooling plate is provided with a hydrophilic microstructure or a hydrophilic coating to increase the critical heat flux density and prevent drying.

4. A microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in any one of claims 1 to 3, characterized in that, The liquid storage tank is also equipped with an electric heating preheating device, which is used to preheat the cooling medium when the ambient temperature is ≤ a preset temperature.

5. A microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in claim 4, characterized in that, The gas-liquid separator is equipped with an exhaust valve at the top to discharge non-condensable gases from the system.

6. A control method for a microchannel liquid cooling system for a wide-temperature-range fuel cell stack, characterized in that, The control method, applied to the microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in claim 1, includes: Receives real-time data on the fuel cell stack temperature; The controller determines whether the temperature of the fuel cell stack is greater than or equal to a set threshold. If not, the three-way switching valve is controlled to open the bypass branch, and the liquid high-pressure pump operates at low frequency to perform single-phase sensible heat cooling. If so, the three-way switching valve is switched to the atomizing nozzle branch, and the liquid high-pressure pump runs at high frequency, so that the coolant is atomized and enters the microchannel heat dissipation cooling plate, and heat dissipation is performed by utilizing the latent heat of phase change.

7. The control method for a microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in claim 6, characterized in that, The method further includes: When the ambient temperature is less than or equal to the preset temperature, the cooling medium is preheated by an electric heating preheating device deployed inside the storage tank.

8. The control method for a microchannel liquid cooling system for a wide-temperature-range fuel cell stack as described in claim 7, characterized in that, The method further includes: The controller adjusts the speed of the high-pressure liquid pump based on the real-time monitored pressure value to maintain pressure stability.

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