Thermal management system for fuel cell

Abstract

The invention relates to a thermal management system for a fuel cell. The thermal management system for the fuel cell comprises a cooling water inlet pipeline, a cooling water loop pipeline, a heat exchanger, an expansion water tank, a first variable-frequency water pump, a liquid cooling unit, a PTC heater, a second variable-frequency water pump and system pipeline fittings which are combined into a cooling circulating water path, a large circulating loop, a small circulating loop and an inner circulating loop, wherein the cooling circulation water path exchanges heat with the large circulation loop through the heat exchanger; the small circulation loop is used for rapidly cooling the fuel cell stack; and the internal circulation loop is used for heating the fuel cell stack at the initial stage of low-temperature cold start. The starting efficiency of the fuel cell stack in the cold starting process can be improved, the internal core of the fuel cell stack can be rapidly cooled in the low-temperature storage stage, and the low-temperature storage time is shortened.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature cold start thermal management testing of a fuel cell stack / module, and in particular to a thermal management system for a fuel cell. Background Art

[0002] 1. Current status of fuel cell stack startup test bench products

[0003] At present, the product technology of fuel cell stack startup test bench is not yet mature.

[0004] 2. Issues in product design and development

[0005] Most product designs and developments are customer-demand oriented, lack standardized testing equipment, and have unreasonable product structure designs that cannot meet the testing requirements of the full power range of 150-300kW.

[0006] 3. Disadvantages of existing cold start test benches on the market

[0007] 1. The volume of the small cycle (internal cycle) is large, and it is difficult to break the ice of the battery stack or the efficiency is low during the cold start process;

[0008] 2. The cooling circuit structure is simple in design;

[0009] 3. When there are bubbles in the pipeline, it is difficult to exhaust. Summary of the invention

[0010] In view of the above problems in the prior art, the present invention proposes a thermal management system for fuel cells, which can improve the startup efficiency of the fuel cell stack during the cold start process, and can quickly cool down the internal core of the fuel cell stack during the low-temperature storage stage, thereby shortening the low-temperature storage time.

[0011] Specifically, the present invention proposes a thermal management system for a fuel cell, including an environmental chamber provided with a fuel cell stack, the thermal management system also includes a cooling water inlet pipeline, a cooling water loop pipeline, a heat exchanger, an expansion water tank, a first variable frequency water pump, a liquid cooling unit, a PTC heater, a second variable frequency water pump and system pipeline accessories, which are combined into a cooling circulation water circuit, a large circulation loop, a small circulation loop and an inner circulation loop; wherein:

[0012] The cooling water in the cooling water circulation circuit flows in the cooling water inlet pipeline, the heat exchanger and the cooling water loop pipeline, and the cooling water circulation circuit exchanges heat with the large circulation loop through the heat exchanger;

[0013] The refrigerant flows in the large circulation loop in the direction of the first variable frequency water pump, the fuel cell stack and the heat exchanger. The large circulation loop dissipates the heat generated by the fuel cell stack through the heat exchanger. The expansion water tank is connected to the large circulation loop. The expansion water tank and the first variable frequency water pump are arranged outside the environmental chamber.

[0014] The small circulation loop is connected in parallel to the large circulation loop, the refrigerant in the small circulation loop flows in the direction of the liquid cooling unit and the fuel cell stack, and the small circulation loop is used to quickly cool the fuel cell stack;

[0015] The inner circulation loop is connected in parallel to the large circulation loop and is arranged in the environmental chamber. The refrigerant flows in the inner circulation loop in the direction of the second variable frequency water pump, the PTC heater, and the fuel cell stack. The inner circulation loop is used to heat the fuel cell stack in the initial stage of low-temperature cold start.

[0016] According to one embodiment of the present invention, in the large circulation loop and in the environmental chamber, a three-way proportional valve is provided in the inlet pipeline connected to the fuel cell stack, and the inner circulation loop is connected to the large circulation loop through the three-way proportional valve.

[0017] According to one embodiment of the present invention, a first proportional valve and a first flow meter are provided in the internal circulation loop, and the refrigerant flow in the internal circulation loop is adjusted by adjusting the speed of the second variable frequency water pump and the opening of the first proportional valve.

[0018] According to one embodiment of the present invention, in the large circulation loop and in the environmental chamber, a first pressure sensor, a first temperature sensor and a first manual valve are arranged in the inlet pipeline connected to the fuel cell stack, and a second pressure sensor, a second temperature sensor and a second manual valve are arranged in the loop pipeline connected to the fuel cell stack.

[0019] According to one embodiment of the present invention, a first switching valve is provided on the inlet pipeline of the liquid cooling unit, and a second switching valve is provided on the loop pipeline of the liquid cooling unit. The liquid cooling unit is connected to the large circulation loop through the first switching valve and the second switching valve, and the small circulation loop is located outside the environmental chamber.

[0020] According to one embodiment of the present invention, a third pressure sensor and a third temperature sensor are provided on the inlet pipeline of the liquid cooling unit, and a fourth pressure sensor and a fourth temperature sensor are provided on the loop pipeline of the liquid cooling unit.

[0021] According to one embodiment of the present invention, a third switching valve is provided on the large circulation loop and on the inlet pipeline connected to the environmental chamber, and a fourth switching valve is provided on the loop pipeline connected to the environmental chamber;

[0022] The third switching valve and the fourth switching valve are opened to start the large circulation loop, and the third switching valve and the fourth switching valve are closed to start the small circulation loop or the inner circulation loop.

[0023] According to one embodiment of the present invention, a second flow meter, a fifth pressure sensor and a fifth temperature sensor are provided on the large circulation loop and on the inlet pipeline connected to the environmental chamber; a sixth pressure sensor and a sixth temperature sensor are provided on the large circulation loop and on the loop pipeline connected to the environmental chamber.

[0024] According to one embodiment of the present invention, a filter, a second proportional valve and a third manual valve are provided on the cooling water inlet pipeline, and a second manual valve is provided on the cooling water loop pipeline.

[0025] According to one embodiment of the present invention, the thermal management system further includes a solenoid valve and a bypass line, one end of the solenoid valve is connected to the outlet line of the large circulation loop in the environmental chamber, and the other end of the solenoid valve is connected to the expansion water tank through the bypass line.

[0026] The present invention provides a thermal management system for a fuel cell, which utilizes an internal circulation loop to improve the startup efficiency of the fuel cell stack during a cold start process, and utilizes a small circulation loop to quickly cool the core of the fuel cell stack during a low-temperature storage stage, thereby shortening the low-temperature storage time.

[0027] It is to be understood that both the foregoing general description and the following detailed description of the present invention are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are included to provide further explanation of the present invention, and are incorporated into and constitute a part of this application. The accompanying drawings illustrate embodiments of the present invention and together with the description serve to explain the principle of the present invention.

[0029] In the attached figure:

[0030] Figure 1 A schematic structural diagram of a thermal management system for a fuel cell according to an embodiment of the present invention is shown.

[0031] The above drawings include the following reference numerals:

[0032] Thermal Management System 100

[0033] Cooling water circuit 200

[0034] Cooling water inlet pipe 201

[0035] Cooling water circuit pipeline 202

[0036] Heat exchanger 203

[0037] Filter 204

[0038] The second proportional valve 205

[0039] Third hand valve 206

[0040] Fourth hand valve 207

[0041] Large circulation loop 300

[0042] Expansion tank 301

[0043] The first variable frequency water pump 302

[0044] Three-way proportional valve 303

[0045] First pressure sensor 305

[0046] First temperature sensor 306

[0047] First Hand Valve 307

[0048] Second pressure sensor 308

[0049] Second temperature sensor 309

[0050] Second hand valve 310

[0051] The third switching valve 311

[0052] Fourth switching valve 312

[0053] Second flow meter 313

[0054] Fifth pressure sensor 314

[0055] Fifth temperature sensor 315

[0056] Sixth pressure sensor 316

[0057] Sixth temperature sensor 317

[0058] Solenoid valve 318

[0059] Manual Butterfly Valve 319

[0060] Small circulation loop 400

[0061] Liquid cooling unit 401

[0062] First switching valve 402

[0063] Second switching valve 403

[0064] The third pressure sensor 404

[0065] The third temperature sensor 405

[0066] Fourth pressure sensor 406

[0067] Fourth temperature sensor 407

[0068] Internal circulation loop 500

[0069] PTC Heater 501

[0070] The second variable frequency water pump 502

[0071] The first proportional valve 503

[0072] First flow meter 504

[0073] Fuel Cell Stack 600

[0074] Environmental Chamber 700 DETAILED DESCRIPTION

[0075] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application may be combined with each other.

[0076] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present application and its application or use. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0077] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0078] Unless otherwise specifically stated, the relative arrangement, numerical expressions and numerical values ​​of the parts and steps set forth in these embodiments do not limit the scope of the application. Meanwhile, it should be understood that, for ease of description, the sizes of the various parts shown in the accompanying drawings are not drawn according to actual proportional relationships. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as a part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, rather than as a limitation. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters represent similar items in the following drawings, and therefore, once a certain item is defined in an accompanying drawing, it does not need to be further discussed in subsequent drawings.

[0079] In the description of the present application, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction, and therefore cannot be understood as limiting the scope of protection of the present application; the directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

[0080] In addition, it should be noted that the use of words such as "first" and "second" to define components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above words have no special meaning and cannot be understood as limiting the scope of protection of this application. In addition, although the terms used in this application are selected from well-known and commonly used terms, some terms mentioned in the specification of this application may be selected by the applicant at his or her discretion, and their detailed meanings are explained in the relevant parts of the description of this article. In addition, it is required to understand this application not only by the actual terms used, but also by the meaning implied by each term.

[0081] Figure 1The schematic diagram of the structure of a thermal management system for a fuel cell according to an embodiment of the present invention is shown. As shown in the figure, a thermal management system 100 for a fuel cell includes an environmental chamber 700 provided with a fuel cell stack. The thermal management system 100 mainly includes a cooling circulation water circuit 200, a large circulation loop 300, a small circulation loop 400 and an inner circulation loop 500. Specifically, the thermal management system 100 includes a cooling water inlet pipeline 201, a cooling water loop pipeline 202, a heat exchanger 203, an expansion water tank 301, a first variable frequency water pump 302, a liquid cooling unit 401, a PTC heater 501, a second variable frequency water pump 502 and system pipeline accessories.

[0082] The cooling water inlet pipeline 201, the cooling water loop pipeline 202 and the heat exchanger 203 constitute the cooling water loop 200. In the cooling water loop 200, the cooling water flows in the cooling water inlet pipeline 201, the heat exchanger 203 and the cooling water loop pipeline 202 according to the arrow direction. The cooling water loop 200 exchanges heat with the large circulation loop 300 through the heat exchanger 203.

[0083] The first variable frequency water pump 302, the fuel cell stack 600 and the heat exchanger 203 form a large circulation loop 300. The first variable frequency water pump 302 and the heat exchanger 203 are arranged outside the environmental chamber 700. In the large circulation loop 300, the refrigerant flows in the first variable frequency water pump 302, the fuel cell stack 600, the heat exchanger 203, and then returns to the first variable frequency water pump 302. The first variable frequency water pump 302 is used to drive the refrigerant to flow in the large circulation loop 300. The large circulation loop 300 mainly takes away the heat generated by the fuel cell stack 600 through the refrigerant and dissipates heat through the heat exchanger 203. The expansion water tank 301 is connected to the large circulation loop 300, and the expansion water tank 301 is arranged outside the environmental chamber 700. One function of the expansion water tank 301 is to compensate for the change in the volume of the refrigerant to maintain the stability of the system pressure. When the temperature of the refrigerant decreases or increases, the volume will change, especially from a low temperature of -40°C to 80°C, the temperature change exceeds 120°C, and the volume of the refrigerant will increase significantly. The expansion tank 301 provides a space for the expansion of the refrigerant volume. Without the expansion tank 301, the expansion of the refrigerant volume may cause the pressure inside the entire circuit to be too high, causing damage or even rupture of components such as pipes and joints. Another function of the expansion tank 301 is to remove air from the system. The air can be exhausted from the system through the exhaust port on the expansion tank 301 to prevent air from forming air blockage in the refrigerant circuit. Air blockage will affect the normal circulation of the refrigerant and cause problems such as local overheating.

[0084] The liquid cooling unit 401 and the fuel cell stack 600 form a small circulation loop 400. The small circulation loop 400 is connected in parallel to the large circulation loop 300. In the small circulation loop 400, the refrigerant flows in the liquid cooling unit 401, the fuel cell stack 600, and then returns to the liquid cooling unit 401. The small circulation loop 400 is used to quickly cool the fuel cell stack 600 and shorten the low-temperature storage time.

[0085] The PTC heater 501, the second variable frequency water pump 502 and the fuel cell stack 600 constitute the inner circulation loop 500. The inner circulation loop 500 is connected in parallel to the large circulation loop 300 and is arranged in the environmental chamber 700. In the inner circulation loop 500, the refrigerant flows in the second variable frequency water pump 502, the PTC heater 501, the second variable frequency water pump 502 and the fuel cell stack 600. The PTC heater 501 is used to heat the refrigerant, and the second variable frequency water pump 502 drives the refrigerant to flow in the inner circulation loop 500. The inner circulation loop 500 plays a vital role in the operation of the fuel cell, and is mainly used to heat the fuel cell stack 600 in the initial stage of low temperature cold start. When in a low temperature environment, the start-up of the fuel cell will face many challenges, and the inner circulation loop 500 will efficiently transmit energy to the fuel cell stack 600, so that its temperature gradually increases, creating suitable conditions for the smooth start-up of the fuel cell, and ensuring that the fuel cell system can operate stably and reliably. Preferably, in some embodiments, the flow rate of the internal circulation refrigerant is controlled by the second variable frequency water pump 502, and the minimum flow rate can be less than 10L / min, which is beneficial to improving the cold start efficiency.

[0086] In some examples, a three-way proportional valve 303 is provided in the inlet pipe of the large circulation loop 300 and the environmental chamber 700 connected to the fuel cell stack 600. The inner circulation loop 500 is connected to the large circulation loop 300 through the three-way proportional valve 303. By controlling the opening of the three-way proportional valve 303, the connection and disconnection of the inner circulation loop 500 and the large circulation loop 300 can be controlled.

[0087] In some examples, a first proportional valve 503 and a first flow meter 504 are provided in the inner circulation loop 500. The speed of the second variable frequency water pump 502 and the opening of the first proportional valve 503 are adjusted to adjust the refrigerant flow in the inner circulation loop 500. The opening of the three-way proportional valve 303 and the opening of the first proportional valve 503 are controlled to control the connection and disconnection of the inner circulation loop 500 and the large circulation loop 300. The first flow meter 504 is used to detect the refrigerant flow in the inner circulation loop 500.

[0088] In some examples, in the large circulation loop 300, and in the environmental chamber 700, a first pressure sensor 305, a first temperature sensor 306 and a first hand valve 307 are set in the inlet pipeline connected to the hydrogen fuel cell stack 600. The first pressure sensor 305 and the first temperature sensor 306 are used to detect the refrigerant pressure and temperature in the inlet pipeline. A second pressure sensor 308, a second temperature sensor 309 and a second hand valve 310 are set in the loop pipeline connected to the fuel cell stack 600 in the environmental chamber 700. The second pressure sensor 308 and the second temperature sensor 309 are used to detect the refrigerant pressure and temperature in the loop pipeline. The thermal management system 100 can switch to the inner circulation loop 500 working mode or the small circulation loop 400 working mode according to the refrigerant flow, refrigerant pressure and temperature in the inlet pipeline, and the refrigerant pressure and temperature in the loop pipeline. The opening and closing of the first hand valve 307 and the second hand valve 310 can realize the opening and closing of the pipeline in the large circulation loop 300 and the fuel cell stack 600.

[0089] In some examples, a first switching valve 402 is provided on the inlet pipeline of the liquid cooling unit 401. A second switching valve 403 is provided on the loop pipeline of the liquid cooling unit 401. The liquid cooling unit 401 is connected to the large circulation loop 300 through the first switching valve 402 and the second switching valve 403 to realize the connection and disconnection of the small circulation loop 400 and the large circulation loop 300. The small circulation loop 400 is located outside the environmental chamber 700, mainly to provide a low-temperature cold source for the fuel cell stack 600, so as to realize the rapid cooling of the fuel cell stack 600.

[0090] In some examples, a third pressure sensor 404 and a third temperature sensor 405 are provided on the inlet pipeline of the liquid cooling unit 401 to obtain the refrigerant pressure and temperature on the inlet pipeline. A fourth pressure sensor 406 and a fourth temperature sensor 407 are provided on the loop pipeline of the liquid cooling unit 401 to obtain the refrigerant pressure and temperature on the loop pipeline. The thermal management system 100 can adjust the flow of cooling water for heat exchange entering the liquid cooling unit 401 according to the refrigerant pressure and temperature in the inlet pipeline of the liquid cooling unit 401, and the refrigerant pressure and temperature in the loop pipeline, so as to improve the cooling efficiency of the fuel cell stack 600, or switch to the large circulation loop 300.

[0091] In some examples, a third switching valve 311 is provided on the large circulation loop 300 and on the inlet pipeline connected to the environmental chamber 700, and a fourth switching valve 312 is provided on the loop pipeline connected to the environmental chamber 700. The third switching valve 311 and the fourth switching valve 312 are opened to start the large circulation loop 300, and the third switching valve 311 and the fourth switching valve 312 are closed to start the small circulation loop 400 or the inner circulation loop 500.

[0092] In some examples, a second flow meter 313, a fifth pressure sensor 314, and a fifth temperature sensor 315 are further provided in the large circulation loop 300 and on the inlet pipeline connected to the environmental chamber 700. The second flow meter 313 is used to detect the refrigerant flow in the inlet pipeline of the large circulation loop 300, and the fifth pressure sensor 314 and the fifth temperature sensor 315 are used to detect the refrigerant pressure and temperature in the inlet pipeline. A sixth pressure sensor 316 and a sixth temperature sensor 317 are also provided in the large circulation loop 300 and on the loop pipeline connected to the environmental chamber 700. The sixth pressure sensor 316 and the sixth temperature sensor 317 are used to detect the refrigerant pressure and temperature in the loop pipeline. The thermal management system 100 can adjust the refrigerant flow rate and the heat exchange efficiency of the heat exchanger 203 according to the refrigerant pressure and temperature in the inlet pipeline of the large circulation loop 300 and the refrigerant pressure and temperature in the loop pipeline.

[0093] In some examples, a filter 204, a second proportional valve 205 and a third hand valve 206 are provided on the cooling water inlet pipeline 201, and a fourth hand valve 207 is provided on the cooling water loop pipeline 202. Various impurities may be mixed into the cooling water during the circulation process, such as rust in the pipeline, dust from the outside, microorganisms, etc. The filter 204 can filter these impurities to protect the normal operation of the cold circulation water circuit and maintain the cooling effect. The thermal management system 100 adjusts the power of the heat exchanger 203 by controlling the opening of the second proportional valve 205. The third hand valve 206 and the fourth hand valve 207 are used to close the cold circulation water circuit.

[0094] In some examples, the temperature of the cooling water in the cooling water inlet pipe 201 is 5-25° C. The temperature of the cooling water connected to the liquid cooling unit 401 is 5-25° C.

[0095] In some examples, the thermal management system 100 also includes a solenoid valve 318 and a bypass line. One end of the solenoid valve 318 is connected to the loop pipeline of the large circulation loop 300 and the fuel cell stack 600 in the environmental chamber 700, and the other end is connected to the expansion tank 301 through a bypass line. When the fuel cell stack 600 is working, bubbles may be generated in the large circulation loop 300 due to various reasons. If these bubbles are not removed in time, it will affect the normal operation of the system and may even cause damage to the equipment. Specifically, by connecting a bypass hose at position a, these bubbles can be quickly discharged from the pipeline through the outlet of the expansion water tank 301, thereby increasing the stability of the operation of the entire system, ensuring that the fuel cell stack 600 can work continuously and efficiently, and providing reliable power support for related equipment and applications. In the exhaust state, the third switching valve 311 is opened, the fourth switching valve 312 is closed, and the solenoid valve 318 is opened. The refrigerant flows as follows: the first variable frequency water pump 302 - the third switching valve 311 - the fuel cell stack 600 - the solenoid valve 318 - the expansion water tank 301, and flows back to the first variable frequency water pump 302.

[0096] In some examples, a manual butterfly valve 319 and a third proportional valve are also connected in parallel to the large circulation loop 300. Among them, the function of the manual butterfly valve 319 is to adjust the refrigerant flow accuracy. Since the starting frequency of the first variable frequency water pump 302 is relatively high, the opening of the manual butterfly valve 319 is regulated to control the flow of the large circulation loop 300. The function of the third proportional valve is to flow back to the loop from the third proportional valve after the large circulation is started during the switching process of the large and small circulations, gradually open the large circulation of the three-way proportional valve 303 until the large circulation is fully opened, and finally close the third proportional valve.

[0097] The specific operation process of the thermal management system 100 in different working stages of the fuel cell stack 600 is described below with reference to the accompanying drawings.

[0098] In the initial stage of the low-temperature cold start of the fuel cell stack 600, the first switching valve 402 and the second switching valve 403, as well as the third switching valve 311 and the fourth switching valve 312 are closed, that is, the large circulation loop 300 and the small circulation loop 400 are closed. The opening of the three-way proportional valve 303 is controlled, the PTC heater 501 and the second variable frequency water pump 502 are started, and the fuel cell stack 600 is heated using the inner circulation loop 500, and the temperature is quickly increased. According to the detection results of the first pressure sensor 305, the first temperature sensor 306, the second pressure sensor 308 and the second temperature sensor 309, after judging that the temperature of the fuel cell stack 600 rises to the target temperature, the third switching valve 311 and the fourth switching valve 312 of the large circulation loop 300 are opened by controlling the opening of the three-way proportional valve 303 and the opening of the first proportional valve 503, and gradually switching from the inner circulation loop 500 to the large circulation loop 300.

[0099] When the fuel cell stack 600 needs to be cooled down quickly, the first switching valve 402 and the second switching valve 403 are opened, and the third switching valve 311 and the fourth switching valve 312 are closed, so that the low-temperature refrigerant in the liquid cooling unit 401 enters the small circulation loop 400 to quickly cool down the fuel cell stack 600.

[0100] When the system pipeline needs to be exhausted, the third switching valve 311 is opened, the fourth switching valve 312 is closed, and the solenoid valve 318 is opened, and the refrigerant flows in the following directions: the first variable frequency water pump 302 - the third switching valve 311 - the fuel cell stack 600 - the solenoid valve 318 - the expansion water tank 301, and flows back to the first variable frequency water pump 302. The gas is discharged through the outlet on the expansion water tank 301.

[0101] The present invention provides a thermal management system for a fuel cell, which mainly includes a cooling circulation water circuit, a large circulation loop, a small circulation loop and an inner circulation loop. The cooling circulation water circuit provides heat dissipation for the large circulation loop through a heat exchanger; the inner circulation loop is located in the environmental chamber and is used in the initial stage of low-temperature cold start of the fuel cell stack; the small circulation loop is used to provide a low-temperature cold source during the purging and cooling process of the fuel cell stack, so that the internal core of the fuel cell stack can be quickly cooled down and the low-temperature storage time can be shortened. The overall structure is compact, and the volume of the inner circulation pipeline can be reduced compared to the prior art, so that the fuel cell can be quickly heated up during the startup process. In addition, the refrigerant flow of the inner circulation loop is controlled by the second variable frequency water pump, and the minimum flow can be less than 10L / min, which is beneficial to improving the cold start efficiency. Adding a small circulation loop can greatly reduce the low-temperature storage time of the fuel cell stack, quickly cool the core, and improve the cold start work efficiency.

[0102] It will be apparent to those skilled in the art that various modifications and variations may be made to the above exemplary embodiments of the present invention without departing from the spirit and scope of the present invention. Therefore, it is intended that the present invention covers modifications and variations of the present invention that fall within the scope of the appended claims and their equivalent technical solutions.

Claims

1. A thermal management system for a fuel cell, comprising an environmental chamber provided with a fuel cell stack, the thermal management system further comprising a cooling water inlet pipeline, a cooling water loop pipeline, a heat exchanger, an expansion water tank, a first variable frequency water pump, a liquid cooling unit, a PTC heater, a second variable frequency water pump and system pipeline accessories, which are combined into a cooling circulation water circuit, a large circulation loop, a small circulation loop and an inner circulation loop; wherein: The cooling water in the cooling water circulation circuit flows in the cooling water inlet pipeline, the heat exchanger and the cooling water loop pipeline, and the cooling water circulation circuit exchanges heat with the large circulation loop through the heat exchanger; The refrigerant flows in the large circulation loop in the direction of the first variable frequency water pump, the fuel cell stack and the heat exchanger. The large circulation loop dissipates the heat generated by the fuel cell stack through the heat exchanger. The expansion water tank is connected to the large circulation loop. The expansion water tank and the first variable frequency water pump are arranged outside the environmental chamber. The small circulation loop is connected in parallel to the large circulation loop, the refrigerant in the small circulation loop flows in the direction of the liquid cooling unit and the fuel cell stack, and the small circulation loop is used to quickly cool the fuel cell stack; The inner circulation loop is connected in parallel to the large circulation loop and is arranged in the environmental chamber. The refrigerant flows in the inner circulation loop in the direction of the second variable frequency water pump, the PTC heater, and the fuel cell stack. The inner circulation loop is used to heat the fuel cell stack in the initial stage of low-temperature cold start.

2. The thermal management system for a fuel cell according to claim 1, wherein: In the large circulation loop and in the environmental chamber, a three-way proportional valve is arranged in the inlet pipeline connected to the fuel cell stack, and the inner circulation loop is connected to the large circulation loop through the three-way proportional valve.

3. The thermal management system for a fuel cell according to claim 1, wherein: A first proportional valve and a first flow meter are provided in the inner circulation loop, and the refrigerant flow in the inner circulation loop is adjusted by adjusting the speed of the second variable frequency water pump and the opening of the first proportional valve.

4. The thermal management system for a fuel cell according to claim 1, wherein: In the large circulation loop and in the environmental chamber, a first pressure sensor, a first temperature sensor and a first manual valve are set in the inlet pipeline connected to the fuel cell stack, and a second pressure sensor, a second temperature sensor and a second manual valve are set in the loop pipeline connected to the fuel cell stack.

5. The thermal management system for a fuel cell according to claim 1, wherein: A first switching valve is provided on the inlet pipeline of the liquid cooling unit, and a second switching valve is provided on the loop pipeline of the liquid cooling unit. The liquid cooling unit is connected to the large circulation loop through the first switching valve and the second switching valve, and the small circulation loop is located outside the environmental chamber.

6. The thermal management system for a fuel cell according to claim 5, characterized in that: A third pressure sensor and a third temperature sensor are provided on the inlet pipeline of the liquid cooling unit, and a fourth pressure sensor and a fourth temperature sensor are provided on the loop pipeline of the liquid cooling unit.

7. The thermal management system for a fuel cell according to claim 1, wherein: A third switching valve is provided on the large circulation loop and on the inlet pipeline connected to the environmental chamber, and a fourth switching valve is provided on the loop pipeline connected to the environmental chamber; The third switching valve and the fourth switching valve are opened to start the large circulation loop, and the third switching valve and the fourth switching valve are closed to start the small circulation loop or the inner circulation loop.

8. The thermal management system for a fuel cell according to claim 7, wherein: A second flow meter, a fifth pressure sensor and a fifth temperature sensor are also provided on the large circulation loop and on the inlet pipeline connected to the environmental chamber; a sixth pressure sensor and a sixth temperature sensor are also provided on the large circulation loop and on the loop pipeline connected to the environmental chamber.

9. The thermal management system for a fuel cell according to claim 1, wherein: A filter, a second proportional valve and a third manual valve are arranged on the cooling water inlet pipeline, and a fourth manual valve is arranged on the cooling water loop pipeline.

10. The thermal management system for a fuel cell according to claim 1, wherein: It also includes a solenoid valve and a bypass pipeline, one end of the solenoid valve is connected to the outlet pipeline of the large circulation loop in the environmental chamber, and the other end of the solenoid valve is connected to the expansion water tank through the bypass pipeline.

Images