Fuel cell system

Abstract

The application relates to a fuel cell system. The system comprises a fuel cell stack, an air inlet main path, an air outlet main path, a cooling liquid main path, a liquid water branch path, a first heat exchange module and an air compressor motor. The air inlet main path is used for inputting air to the fuel cell stack; a turbine is arranged on the air outlet main path, the turbine is connected with a compressor of the air inlet main path through the air compressor motor, a water separator is arranged on the air outlet main path; the liquid water branch path is used for discharging liquid water separated by the water separator; a first end of the cooling liquid main path is connected with a cooling liquid outlet of the fuel cell stack, a second end of the cooling liquid main path is connected with a cooling liquid inlet of the fuel cell stack; the first heat exchange module is used for heating the water separator on the air outlet main path according to cooling liquid on the cooling liquid main path. By using the system, liquid water can be prevented from entering the turbine in a low-temperature environment, so that the turbine is prevented from being damaged.

Description

Technical Field

[0001] This application relates to the field of fuel cell technology, and in particular to a fuel cell system. Background Technology

[0002] A fuel cell is an energy conversion device that uses the electrochemical reaction between hydrogen and oxygen to directly convert chemical energy into electrical energy. For a fuel cell to operate efficiently and reliably, it needs a sufficient air supply to the cathode, while also meeting temperature, humidity, and pressure requirements. The air compressor provides the fuel cell with sufficient airflow and pressure, and is also the most energy-intensive component in the fuel cell engine. As the power of fuel cells increases, the pressure ratio and flow rate requirements for the air compressor also increase, leading to higher energy consumption for the air compressor.

[0003] Currently, centrifugal air compressors have become the mainstream air compressors for fuel cell engines due to their advantages such as small size, oil-free operation, low noise, and high efficiency. Centrifugal air compressors also facilitate the integration of turbines, enabling energy recovery and reducing compressor energy consumption. However, because the turbine in a turbine-equipped centrifugal air compressor operates at high speeds, typically tens of thousands of revolutions per minute, even a small amount of liquid water or solid matter entering can cause significant damage to the turbine and potentially destroy the entire air compressor. Summary of the Invention

[0004] Therefore, it is necessary to provide a fuel cell system that can prevent liquid from entering the air compressor, addressing the aforementioned technical problems.

[0005] To achieve the above and other objectives, this application provides a fuel cell system. The fuel cell system includes: a fuel cell stack, an intake main line, an exhaust main line, a coolant main line, a liquid water branch line, a first heat exchange module, and an air compressor motor, wherein...

[0006] The first end of the main air intake is used to input air, and the second end of the main air intake is connected to the air intake end of the fuel cell stack for inputting air into the fuel cell stack. A compressor is provided on the main air intake.

[0007] The first end of the exhaust main line is connected to the air outlet of the fuel cell stack. A turbine is provided on the exhaust main line. The first end of the turbine serves as the second end of the exhaust main line and is connected to the compressor via the air compressor motor. The third end of the exhaust main line is used to output air to the outside. A water separator is provided on the exhaust main line.

[0008] The liquid water branch is connected to the outlet of the water separator and is used to discharge the liquid water separated by the water separator;

[0009] The first end of the main coolant inlet is connected to the coolant outlet of the fuel cell stack, and the second end of the main coolant inlet is connected to the coolant inlet of the fuel cell stack; wherein,

[0010] The first heat exchange module is disposed on the main coolant line and the main exhaust line, and is used to heat the water separator in the main exhaust line according to the coolant in the main coolant line.

[0011] In one embodiment, the turbine inlet is connected to the water separator, and the turbine outlet serves as the third end of the main exhaust path.

[0012] The air inlet of the first heat exchange module is connected to the exhaust main line, the air outlet of the first heat exchange module is connected to the turbine inlet, and the coolant inlet and coolant outlet of the first heat exchange module are respectively connected to the coolant main line.

[0013] In one embodiment, a drain valve connected to the outlet of the water separator is provided on the liquid water branch, wherein the water separator, the drain valve, part of the exhaust main line and part of the liquid water branch are all housed within the first heat exchange module.

[0014] In one embodiment, the main coolant circuit includes a first branch, a second branch, a water pump, and a third branch. The coolant outlet of the fuel cell stack is connected to the coolant inlet of the first heat exchange module via the first branch, the coolant outlet of the first heat exchange module is connected to the inlet of the water pump via the second branch, and the outlet of the water pump is connected to the coolant inlet of the fuel cell stack via the third branch.

[0015] In one embodiment, the main coolant circuit further includes a fourth branch, a three-way valve, and a second heat exchange module. The second heat exchange module is disposed on the third branch. The three terminals of the three-way valve are respectively connected to the coolant inlet of the fuel cell stack, the first end of the fourth branch, and the first end of the third branch. The second end of the third branch and the second end of the fourth branch are respectively connected to the outlet of the water pump.

[0016] In one embodiment, the fuel cell system further includes a heating module positioned between the three-way valve and the coolant inlet of the fuel cell stack.

[0017] In one embodiment, the fuel cell system further includes a bypass branch connected to the coolant outlet of the fuel cell stack and the inlet of the water pump, respectively.

[0018] In one embodiment, a filter and an air cooler are sequentially arranged on the main intake path. The first end of the filter serves as the first end of the main intake path, the second end of the filter is connected to the first end of the compressor, the second end of the compressor is connected to the air compressor motor, the first end of the air cooler is connected to the third end of the compressor, and the second end of the air cooler is connected to the intake end of the fuel cell stack.

[0019] In one embodiment, the fuel cell system further includes an intake branch, wherein a pipeline between the compressor and the air cooler is connected to a first end of the intake branch, a second end of the intake branch is connected to the exhaust main pipeline connected to the inlet of the water separator, and an air bypass valve is provided on the intake branch.

[0020] In one embodiment, the fuel cell system further includes:

[0021] A humidifier is installed on the main intake duct and the main exhaust duct;

[0022] An intake shut-off valve is installed on the main intake line between the humidifier and the intake end of the fuel cell stack;

[0023] An exhaust shut-off valve is installed on the main exhaust line between the humidifier and the exhaust end of the fuel cell stack.

[0024] In the aforementioned fuel cell system, the main intake path is connected to the intake end of the fuel cell stack to provide the cathode of the fuel cell with air of the required temperature, humidity, and flow rate. The main exhaust path is connected to the outlet end of the fuel cell stack to exhaust gas. A turbine is installed on the main exhaust path to drive the compressor through the air compressor motor based on the power of the exhaust gas, thereby improving the efficiency of the compressor's input air and facilitating the recovery of exhaust energy to reduce power consumption. A water separator is used to separate liquid from the gas output from the outlet end of the fuel cell stack to prevent liquid from entering the turbine and causing turbine damage. The coolant flowing out of the fuel cell stack coolant outlet is heated by the fuel cell stack, and the first heat exchange module is used to transfer the heat of the heated coolant to the water separator to prevent the water separator from freezing and failing in low-temperature environments, which could lead to liquid entering the turbine and causing turbine damage. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the fuel cell system provided in the first embodiment of this application;

[0027] Figure 2 This is a schematic diagram of the fuel cell system provided in the second embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the fuel cell system provided in the third embodiment of this application;

[0029] Figure 4 This is a schematic diagram of the fuel cell system provided in the fourth embodiment of this application;

[0030] Figure 5 This is a schematic diagram of the fuel cell system provided in the fifth embodiment of this application;

[0031] Figure 6 This is a schematic diagram of the fuel cell system provided in the sixth embodiment of this application;

[0032] Figure 7 This is a temperature curve diagram of the inside and outside of the pipeline before the first heat exchange module is used during engine startup in one embodiment of this application;

[0033] Figure 8 This is a temperature curve of the inside and outside of the pipeline after the first heat exchange module is used during engine startup in one embodiment of this application;

[0034] Figure 9 This is a temperature curve diagram of the inside and outside of the pipeline before the first heat exchange module is used when the engine is operating normally, according to one embodiment of this application.

[0035] Figure 10 This is a temperature curve of the inside and outside of the pipeline after the engine uses the first heat exchange module during normal operation in one embodiment of this application;

[0036] Figure 11 This is a graph showing the wall temperature of the pipe before the first heat exchange module is used when the engine is stopped, according to one embodiment of this application.

[0037] Figure 12 This is a graph showing the wall temperature of the pipeline after the first heat exchange module is used when the engine is stopped, according to one embodiment of this application.

[0038] Explanation of reference numerals in the attached figures:

[0039] 10. Fuel cell system; 100. Fuel cell stack; 200. Main intake path; 210. Compressor; 220. Filter; 230. Air cooler; 240. Intake branch path; 241. Air bypass valve; 250. Intake shut-off valve; 300. Main exhaust path; 310. Water separator; 320. Turbine; 330. Exhaust shut-off valve; 400. Main coolant path; 410. First heat exchange module; 420. First branch path; 430. Second branch path; 440. Water pump; 450. Third branch path; 460. Fourth branch path; 470. Three-way valve; 480. Second heat exchange module; 490. Heating module; 500. Liquid water branch path; 510. Drain valve; 600. Air compressor motor; 700. Bypass branch path; 800. Humidifier. Detailed Implementation

[0040] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings, which illustrate embodiments of the present application. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided so that the disclosure of this application will be thorough and complete.

[0041] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application.

[0042] It is understood that the terms “first,” “second,” etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another.

[0043] It should be noted that when one element is considered to be "connected" to another element, it can be directly connected to the other element or connected to the other element through an intermediary element. Furthermore, in the following embodiments, "connection" should be understood as "electrical connection," "communication connection," etc., if there is transmission of electrical signals or data between the connected objects.

[0044] When used herein, the singular forms of “a,” “an,” and “the” may also include the plural forms unless the context clearly indicates otherwise. It should also be understood that the terms “including / contains” or “having,” etc., specify the presence of the stated feature, whole, component, part, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, wholes, components, parts, or combinations thereof.

[0045] In one embodiment, such as Figure 1As shown, a fuel cell system 10 is provided. The fuel cell system 10 includes: a fuel cell stack 100, an intake main line 200, an exhaust main line 300, a coolant main line 400, a liquid water branch line 500, a first heat exchange module 410, and an air compressor motor 600.

[0046] The first end of the main air intake 200 is connected to the external environment and is used to input air from the external environment; the second end of the main air intake 200 is connected to the air intake end of the fuel cell stack 100 and is used to input air into the fuel cell stack 100; a compressor 210 is provided on the main air intake 200; the main air intake 200 is used to provide the fuel cell stack 100 with air of the required temperature, humidity and flow rate.

[0047] The first end of the exhaust main duct 300 is connected to the outlet end of the fuel cell stack 100, and is used to output the gas generated after the air passes through the fuel cell stack 100. A turbine 320 is installed on the exhaust main duct 300. The first end of the turbine 320 serves as the second end of the exhaust main duct 300 and is connected to the compressor 210 via the air compressor motor 600. The third end of the exhaust main duct 300 is used to output air to the outside. The turbine 320, the air compressor motor 600, and the compressor 210 are coaxial. The turbine 320 and the air compressor motor 600 simultaneously drive the compressor 210 to rotate. The gas output from the outlet end of the fuel cell stack 100 enters the turbine 320 through the pipe of the exhaust main duct 300, performs work on the turbine 320, recovers exhaust energy, and thus reduces the energy consumption of the air compressor motor 600. However, due to the high speed of the turbine, usually tens of thousands of revolutions per minute, even a small amount of liquid or solid entering the turbine can cause great damage or even damage the air compressor. Therefore, the liquid is separated by the water separator 310 and discharged through the liquid water branch 500 to prevent the presence of liquid in the gas obtained by the turbine 320.

[0048] The first end of the main coolant line 400 is connected to the coolant outlet of the fuel cell stack 100, and the second end of the main coolant line 400 is connected to the coolant inlet of the fuel cell stack 100. A first heat exchange module 410 is installed on both the main coolant line 400 and the main exhaust line 300, using the coolant on the main coolant line 400 to heat the water separator 310 in the main exhaust line 300. Because the drain pipe of the water separator 310 will freeze during cold start of the fuel cell in low-temperature environments, and the temperature of the coolant output after the reaction in the fuel cell stack 100 is higher than the ambient temperature, by guiding the reacted coolant to the first heat exchange module 410, which then uses the coolant temperature to heat the water separator 310, the freezing of the drain pipe of the water separator 310 can be avoided.

[0049] The aforementioned fuel cell system 10 has an intake main duct 200 connected to the intake end of the fuel cell stack 100 to provide the cathode of the fuel cell with air of the required temperature, humidity, and flow rate; an exhaust main duct 300 connected to the outlet end of the fuel cell stack 100 to exhaust gas; a turbine 320 mounted on the exhaust main duct 300 to drive the compressor 210 to rotate via the shaft of the air compressor motor 600 based on the power of the exhaust gas, thereby recovering exhaust energy and reducing the power consumption of the air compressor motor 600; a water separator 310 to separate liquid water from the gas output from the outlet end of the fuel cell stack 100 to prevent liquid water from entering the turbine 320 and causing damage to the turbine 320; after the coolant flowing out of the coolant outlet of the fuel cell stack 100 is heated by the fuel cell stack 100, the first heat exchange module 410 transfers the heat of the heated coolant to the water separator 310 to prevent the water separator 310 from freezing and failing in low-temperature environments, which would cause liquid water to enter the turbine 320 and cause damage to the turbine 320.

[0050] In one embodiment, such as Figure 2 The turbine 320's inlet is connected to the water separator 310, and the turbine 320's outlet serves as the third end of the exhaust main duct 300. The air inlet of the first heat exchange module 410 is connected to the exhaust main duct 300, and the air outlet of the first heat exchange module 410 is connected to the turbine 320's inlet. The coolant inlet and coolant outlet of the first heat exchange module 410 are respectively connected to the coolant main duct 400. A drain valve 510 connected to the outlet of the water separator 310 is provided on the liquid water branch 500. The water separator 310, drain valve 510, part of the exhaust main duct 300, and part of the liquid water branch 500 are all housed within the first heat exchange module 410. Part of the exhaust main duct 300 serves as the passage between the water separator 310 and the turbine 320, and part of the liquid water branch 500 serves as the passage between the water outlet of the water separator 310 and the drain valve 510. The drain valve 510 can be a throttling orifice used to control the drainage flow rate.

[0051] The aforementioned fuel cell system 10 recovers some exhaust energy through the inlet of the turbine 320. The exhaust power drives the compressor 210 via the shaft of the air compressor motor 600, thus recovering exhaust energy and reducing the energy consumption of the air compressor motor 600. However, in low-temperature environments, during cold starts of the fuel cell, the temperature of the air inside the exhaust pipe increases as the engine starts, but the temperature outside the exhaust pipe remains very low. This leads to cooling of the air inside the pipe by the pipe surface, causing water vapor to condense into liquid water. Especially in the section of pipe connecting the water separator 310 and the turbine 320, if the temperature outside the main exhaust pipe 300 is lower than the temperature inside the main exhaust pipe 300, liquid water will condense in the main exhaust pipe 300 after the water separator 310 and enter the turbine 320, causing damage to the turbine 320. In low-temperature environments, the drain valve 510 may freeze, preventing the discharge of liquid separated by the water separator 310, causing the water separator 310 to fail and liquid to enter the turbine 320. Therefore, the first heat exchange module 410 heats the water separator 310, drain valve 510, and part of the main exhaust path 300, making the surface temperature of part of the main exhaust path 300 similar to the temperature of the coolant output from the fuel cell stack 100. As the engine starts, the temperature of the coolant and the temperature of the main exhaust path 300 rise simultaneously. The coolant temperature, after passing through the first heat exchange module 410, heats part of the main exhaust path 300, causing the surface temperature of the main exhaust path 300 and the temperature of the air inside the main exhaust path 300 to rise simultaneously. This avoids water vapor condensation caused by the cooling effect on the surface of the main exhaust path 300. The coolant temperature, after passing through the first heat exchange module 410, heats the water separator 310, drain valve 510, and part of the liquid water branch path 500, preventing the drain valve 510 or the liquid water branch path 500 from freezing at low temperatures, which could lead to the failure of the water separator 310.

[0052] In one embodiment, such as Figure 3 The main coolant circuit 400 includes a first branch circuit 420, a second branch circuit 430, a water pump 440, a third branch circuit 450, a fourth branch circuit 460, a three-way valve 470, and a second heat exchange module 480. The coolant outlet of the fuel cell stack 100 is connected to the coolant inlet of the first heat exchange module 410 via the first branch circuit 420. The coolant outlet of the first heat exchange module 410 is connected to the inlet of the water pump 440 via the second branch circuit 430. The outlet of the water pump 440 is connected to the coolant inlet of the fuel cell stack 100 via the third branch circuit 450. The main coolant circuit 400 also includes a second heat exchange module 480 disposed on the third branch circuit 450. The three terminals of the three-way valve 470 are respectively connected to the coolant inlet of the fuel cell stack 100, the first end of the fourth branch circuit 460, and the first end of the third branch circuit 450. The second ends of the third branch circuit 450 and the second ends of the fourth branch circuit 460 are respectively connected to the outlet of the water pump 440.

[0053] Optionally, the fuel cell system 10 also includes a heating module 490 disposed between the three-way valve 470 and the coolant inlet of the fuel cell stack 100. The heating module 490 is a device that can raise the temperature of the coolant; it can be a PTC heater or a heat exchanger. By heating the coolant at the coolant inlet of the fuel cell stack 100 through the heating module 490, the coolant temperature rises, thereby raising the temperature of the fuel cell stack 100 and enabling cold start of the fuel cell in low-temperature environments.

[0054] The aforementioned fuel cell system 10 includes a second heat exchange module 480 comprising a heat exchanger and a fan. The heat exchanger transfers heat from the coolant to the external environment for heating gases, liquids, or solids in the environment. The fan circulates air through the heat exchanger, thereby lowering its temperature. Simultaneously, the coolant temperature after passing through the second heat exchange module 480 is reduced, falling below the coolant temperature at the outlet of the water pump 440. The three-way valve 470 allows selection of whether the coolant flowing from the outlet of the water pump 440 is directly transmitted to the coolant inlet of the fuel cell stack 100, or whether the coolant flowing from the outlet of the water pump 440 undergoes heat conversion in the second heat exchange module 480 before being transmitted to the coolant inlet of the fuel cell stack 100. For example, when the fuel cell is in a cold start state, the temperature of the coolant entering the fuel cell stack 100 should be as high as possible. At this time, the port connecting the three-way valve 470 and the second heat exchange module 480 is closed, so that the coolant from the outlet of the water pump 440 is not cooled by the second heat exchange module 480, but is directly transmitted to the coolant inlet of the fuel cell stack 100, so that the temperature of the fuel cell stack 100 rises.

[0055] In one embodiment, such as Figure 4 The fuel cell system 10 also includes a bypass branch 700 that is connected to the coolant outlet of the fuel cell stack 100 and the inlet of the water pump 440.

[0056] In the aforementioned fuel cell system 10, a portion of the coolant flowing from the coolant outlet of the fuel cell stack 100 is transmitted to the first heat exchange module 410 via the first branch 420 to heat the water separator 310, and then transmitted to the coolant inlet of the water pump 440 via the second branch 430; the other portion is directly transmitted to the coolant inlet of the water pump 440 via the bypass branch 700. This portion of the coolant does not undergo heat exchange treatment by the first heat exchange module 410 and is used to reduce the pressure drop of the fuel cell cooling system.

[0057] In one embodiment, such as Figure 5The intake main duct 200 is sequentially equipped with a filter 220 and an air cooler 230. The first end of the filter 220 serves as the first end of the intake main duct 200, and the second end of the filter 220 is connected to the first end of the compressor 210. The second end of the compressor 210 is connected to the air compressor motor 600. The first end of the air cooler 230 is connected to the third end of the compressor 210, and the second end of the air cooler 230 is connected to the intake end of the fuel cell stack 100. The fuel cell system 10 also includes an intake branch 240, wherein the pipeline between the compressor 210 and the air cooler 230 is connected to the first end of the intake branch 240, and the second end of the intake branch 240 is connected to the exhaust main duct 300 connected to the inlet of the water separator 310. An air bypass valve 241 is provided on the intake branch 240. The intake branch 240 is used to prevent surge in the compressor 210. Since surge in fuel cell engines generally occurs under low load, the temperature after compressor 210 may be lower than the cathode outlet temperature of fuel cell stack 100. When intake branch 240 merges into exhaust main 300, liquid water will condense. Therefore, the position where intake branch 240 merges into exhaust main 300 must be before water separator 310.

[0058] The aforementioned fuel cell stack 100 increases the pressure of the input air through a turbine 320, an air compressor motor 600, and a compressor 210. Air passing through the fuel cell stack 100 is bypassed via an intake branch 240 to prevent surge in the compressor 210. When the compressor 210 surges, the air bypass valve 241 is opened, allowing a portion of the air output from the compressor 210 to be recovered to the air compressor via a water separator 310; the remaining portion is recovered to the compressor 210 after reacting in the fuel cell stack 100, thus preventing surge in the compressor 210.

[0059] In one embodiment, such as Figure 6 The fuel cell system 10 also includes a humidifier 800, which is installed on the main intake passage 200 and the main exhaust passage 300; an intake shut-off valve 250, which is installed on the main intake passage 200 between the humidifier 800 and the intake end of the fuel cell stack; and an exhaust shut-off valve 330, which is installed on the main exhaust passage 300 between the humidifier 800 and the exhaust end of the fuel cell stack.

[0060] During normal startup of the fuel cell, the intake shut-off valve 250 and the exhaust shut-off valve 330 are opened, and the air compressor motor 600 and water pump 440 are started. Ambient air, filtered by filter 220, is then transmitted to the first port of compressor 210. Compressor 210 uses high-speed rotating blades to perform work on the air to increase its pressure.

[0061] The pressurized air is transmitted to the air inlet of the fuel cell stack 100 after passing through the air cooler 230 and humidifier 800. After the air reacts in the fuel cell stack 100, it is discharged from the air outlet of the fuel cell stack 100.

[0062] The output gas passes through the humidifier 800 and then reaches the water separator 310, where liquid water is separated from the output gas and discharged through the liquid water branch 500. The separated gas is then directly discharged into the external environment through the turbine 320. The turbine 320 generates power based on the gas flow, which is then transmitted through the shaft of the air compressor motor 600.

[0063] This drives the compressor 210 to rotate, thereby reducing the power consumption of the air compressor motor 600. If the compressor 210 experiences surge, the air bypass valve 241 is opened, allowing the air output from the third port of the compressor 210 to directly reach the inlet of the water separator 310 for liquid water separation.

[0064] During a cold start of the fuel cell, air flows through the main intake path 200, the fuel cell stack 100, and reaches the main exhaust path 300. Because both the ambient temperature and the fuel cell engine temperature are low, the cathode outlet of the fuel cell stack will...

[0065] A large amount of liquid water is produced, which needs to be separated by water separator 310. However, due to the low temperature, the wall temperature of the pipe between water separator 310 and turbine 320 is lower than the gas temperature inside the pipe.

[0066] like Figure 7 This condensation produces liquid water that enters the turbine 320, causing damage. Furthermore, due to the low temperature, the portion of the liquid water branch 500 between the drain valve 510 and the water separator 310 will freeze, preventing the liquid water separated by the water separator 310 from draining. Therefore, a first heat exchange unit is installed.

[0067] The coolant from the coolant outlet of the fuel cell stack 100 heats the water separator 310, a portion of the main exhaust pipe 300 between the water separator 310 and the turbine 320, the drain valve 510, and a portion of the liquid water branch pipe 500 between the drain valve 510 and the water separator 310, so that the pipe wall temperature of the portion of the main exhaust pipe 300 between the water separator 310 and the turbine 320 is lower than the gas temperature inside the pipe. Figure 8This prevents condensation of liquid water and also prevents ice formation in the drain valve 510 and the liquid water branch 500 between the drain valve 510 and the water separator 310, ensuring the normal operation of the water separator 310. During cold start, the port connecting the three-way valve 470 to the second heat exchange module 480 is closed, while the port connecting the three-way valve 470 to the outlet of the water pump 440 is open. Coolant flowing from the outlet of the water pump 440 is directly input to the coolant inlet of the fuel cell stack 100, facilitating temperature rise. When the coolant temperature exceeds a set value, the fourth branch 460 between the three-way valve 470 and the water pump 440 is disconnected, and the third branch 450 between the three-way valve 470 and the second heat exchange module 480 is closed. The heat exchanger and fan in the second heat exchange module 480 work together to reduce the coolant temperature.

[0068] When the fuel cell is operating normally, before the first heat exchange module 410 is installed, the temperature of the exhaust main duct 300 between the water separator 310 and the turbine 320 is as follows: Figure 9 At this time, the pipe wall temperature is consistently lower than the gas temperature inside the pipe. Due to the low wall temperature, additional liquid water will enter the turbine 320, potentially damaging it. After the first heat exchange module 410 is installed, it uses the heat from the coolant to heat a portion of the main exhaust pipe 300 between the water separator 310 and the turbine 320. At this point, the pipe temperature is as follows: Figure 10 The wall temperature of the exhaust main duct 300 is consistently higher than the gas temperature. This indicates that no additional liquid water will enter the turbine 320 due to the low wall temperature.

[0069] After the fuel cell shuts down, the fuel cell engine cools down naturally. Because the density and specific heat capacity of the coolant are much greater than those of the gas in the exhaust main duct 300, the cooling rate of the gas is generally greater than that of the coolant; that is, the wall temperature in contact with the coolant is higher than the wall temperature without coolant contact. Since the fuel cell stack 100 is a heat source during cooling, the gas temperature is higher closer to the fuel cell stack 100. This results in the wall temperature of the water separator 310, the drain valve 510, and the portion of the exhaust main duct 300 connecting the water separator 310 and the turbine 320 being lower than the temperature of the exhaust main duct 300 before the water separator 310. Figure 11This can lead to condensation of liquid water on the inner surfaces of the water separator 310, drain valve 510, and the portion of the main exhaust passage 300 connecting the water separator 310 and the turbine 320. Upon the next startup, this liquid water will enter the turbine 320, causing damage. If there is liquid water on the inner surface of the drain valve 510, it may freeze below zero degrees Celsius, preventing drainage and allowing liquid water to enter the turbine 320, causing further damage. After the first heat exchange module 410 is installed, the heat of the coolant in the first heat exchange module 410 heats a portion of the exhaust main passage 300 between the water separator 310 and the turbine 320. This makes the wall temperature of the water separator 310, the drain valve 510, and the portion of the exhaust main passage 300 connecting the water separator 310 and the turbine 320 similar to that of the cooling water, but higher than the wall temperature of the exhaust main passage 300 before the water separator 310. This causes condensation to occur before the water separator 310, preventing condensed water from entering the turbine 320 and freezing the drain valve 510. Figure 12 The wall temperature of the portion of the main exhaust path 300 between the water separator 310 and the turbine 320 is consistently higher than the wall temperature of the portion of the main exhaust path 300 before the water separator 310. In other words, the wall temperature of the water separator 310, the drain valve 510, and the portion of the main exhaust path 300 connecting the water separator 310 and the turbine 320 is consistently higher than the wall temperature of the pipe before the water separator 310. This indicates that water vapor in the main exhaust path 300 tends to condense in the pipe before the water separator 310.

[0070] The aforementioned fuel cell system 10 uses the heat from the coolant in the first heat exchange module 410 to heat the water separator 310, drain valve 510, a portion of the main exhaust path 300 between the water separator 310 and the turbine 320, and a portion of the liquid water branch path 500 between the water separator 310 and the drain valve 510. This prevents the drain valve 510 and the portion of the liquid water branch path 500 between the water separator 310 and the drain valve 510 from freezing during engine cold starts and normal operation, thus preventing the water separator 310 from failing to drain. At the same time, it prevents liquid water from being generated in the portion of the main exhaust path 300 between the water separator 310 and the turbine 320, thus preventing damage to the turbine 320. After the engine stops, it ensures that the wall temperature of the water separator 310, drain valve 510, and the portion of the main exhaust path 300 connecting the water separator 310 and the turbine 320 is always higher than the temperature of other components and pipes in the air path. As the temperature decreases, liquid water preferentially condenses on the wall surface where the temperature is lower, thus preventing liquid water from condensing on the walls of the water separator 310, drain valve 510, and the part of the exhaust main passage 300 connecting the water separator 310 and the turbine 320, which would otherwise generate liquid water that could damage the turbine 320.

[0071] In the description of this specification, references to terms such as "some embodiments," "other embodiments," and "ideal embodiments" indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, the illustrative descriptions of the above terms do not necessarily refer to the same embodiments or examples.

[0072] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0073] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A fuel cell system, characterized in that, include: The fuel cell stack includes an intake main line, an exhaust main line, a coolant main line, a liquid water branch line, a first heat exchange module, and an air compressor motor. The first end of the main air intake is used to input air, and the second end of the main air intake is connected to the air intake end of the fuel cell stack for inputting air into the fuel cell stack. A compressor is provided on the main air intake. The first end of the exhaust main line is connected to the air outlet of the fuel cell stack. A turbine is provided on the exhaust main line. The first end of the turbine serves as the second end of the exhaust main line and is connected to the compressor via the air compressor motor. The third end of the exhaust main line is used to output air to the outside. A water separator is provided on the exhaust main line. The liquid water branch is connected to the outlet of the water separator and is used to discharge the liquid water separated by the water separator; The first end of the main coolant line is connected to the coolant outlet of the fuel cell stack, and the second end of the main coolant line is connected to the coolant inlet of the fuel cell stack. The main coolant circuit includes a first branch, a second branch, a water pump, and a third branch. The coolant outlet of the fuel cell stack is connected to the coolant inlet of the first heat exchange module via the first branch. The coolant outlet of the first heat exchange module is connected to the inlet of the water pump via the second branch. The outlet of the water pump is connected to the coolant inlet of the fuel cell stack via the third branch. The fuel cell system also includes a heating module for heating the coolant at the inlet of the fuel cell stack. in, The first heat exchange module is disposed on the main coolant line and the main exhaust line, and is used to heat the water separator on the main exhaust line according to the coolant in the main coolant line.

2. The fuel cell system according to claim 1, characterized in that, The turbine inlet is connected to the water separator, and the turbine outlet serves as the third end of the main exhaust path. The air inlet of the first heat exchange module is connected to the exhaust main line, the air outlet of the first heat exchange module is connected to the turbine inlet, and the coolant inlet and coolant outlet of the first heat exchange module are respectively connected to the coolant main line.

3. The fuel cell system according to claim 2, characterized in that, The liquid water branch is provided with a drain valve connected to the outlet of the water separator, wherein the water separator, the drain valve, part of the exhaust main line and part of the liquid water branch are all housed within the first heat exchange module.

4. The fuel cell system according to claim 1, characterized in that, The main coolant circuit also includes a fourth branch, a three-way valve, and a second heat exchange module. The second heat exchange module is located on the third branch. The three terminals of the three-way valve are respectively connected to the coolant inlet of the fuel cell stack, the first end of the fourth branch, and the first end of the third branch. The second end of the third branch and the second end of the fourth branch are respectively connected to the outlet of the water pump.

5. The fuel cell system according to claim 4, characterized in that, The fuel cell system further includes a heating module positioned between the three-way valve and the coolant inlet of the fuel cell stack.

6. The fuel cell system according to claim 1, characterized in that, The fuel cell system further includes a bypass branch connected to the coolant outlet of the fuel cell stack and the inlet of the water pump, respectively.

7. The fuel cell system according to claim 1, characterized in that, A filter and an air cooler are sequentially arranged on the main air intake path. The first end of the filter serves as the first end of the main air intake path. The second end of the filter is connected to the first end of the compressor. The second end of the compressor is connected to the air compressor motor. The first end of the air cooler is connected to the third end of the compressor. The second end of the air cooler is connected to the air intake end of the fuel cell stack.

8. The fuel cell system according to claim 7, characterized in that, The fuel cell system further includes an intake branch, wherein the pipeline between the compressor and the air cooler is connected to a first end of the intake branch, the second end of the intake branch is connected to the exhaust main pipeline connected to the inlet of the water separator, and an air bypass valve is provided on the intake branch.

9. The fuel cell system according to claim 1, characterized in that, The fuel cell system also includes: A humidifier is installed on the main intake duct and the main exhaust duct; An intake shut-off valve is installed on the main intake line between the humidifier and the intake end of the fuel cell stack; An exhaust shut-off valve is installed on the main exhaust line between the humidifier and the exhaust end of the fuel cell stack.

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