Fuel cell engine thermal management system and method of controlling the same

Abstract

The application provides a fuel cell engine thermal management system and a control method thereof, wherein the former comprises a controller, an electric pile, a first water pump, a first heater, a first electromagnetic valve, a second electromagnetic valve, a deionizer, a second heater, a second water pump, an intercooler and a water filter, two ends of the electric pile are connected with inlet and outlet water pipelines respectively, a third electromagnetic valve and an inlet pile temperature sensor are arranged on the inlet water pipeline, a fourth electromagnetic valve and an outlet pile temperature sensor are arranged on the outlet water pipeline, the first electromagnetic valve, the first water pump, the first heater and the second electromagnetic valve are sequentially arranged on a first pipeline, the deionizer is arranged on a second pipeline, the second heater is arranged on a third pipeline, the second water pump, the intercooler and the water filter are sequentially arranged on a fourth pipeline, two ends of each pipeline are connected with the inlet and outlet water pipelines respectively, and the two water pumps, the first heater, each temperature sensor and each electromagnetic valve are electrically connected with the controller. The application can shorten the cold start time of the fuel cell engine.

Description

Technical Field

[0001] This invention belongs to the field of vehicle safety testing technology, specifically relating to a thermal management system for a fuel cell engine and its control method. Background Technology

[0002] The core components of a fuel cell engine, including the stack and accessories, need to operate within a suitable temperature range. Excessively high or low temperatures can degrade stack performance, necessitating a well-designed and efficient thermal management system. During cold starts in low-temperature environments (typically below -30°C), the initial reaction rate of the fuel cell stack is low, resulting in insufficient heat to rapidly raise its temperature. The water produced in the reaction freezes under the influence of the low temperature, leading to cold start failure.

[0003] To avoid cold start failure of fuel cell engines, existing technologies, such as Chinese invention patent CN207705315U, disclose a thermal management system for commercial vehicle fuel cells, such as... Figure 1 As shown, however, during the cold start of a fuel cell engine, the small circulation path used consists of an electronically controlled three-way valve 3, an electric heater 4, a variable frequency water pump 9, a deionization device 7, a throttle valve 8, and a particulate filter 10. This small circulation path has many components, leading to significant heat loss and thus a longer cold start time for the fuel cell engine. Therefore, how to design a thermal management system for a fuel cell engine to effectively shorten the cold start time has become a pressing technical problem for those skilled in the art. Summary of the Invention

[0004] The purpose of this invention is to provide a thermal management system for a fuel cell engine to solve the aforementioned technical problems in the prior art. Another purpose of this invention is to provide a control method for a thermal management system for a fuel cell engine.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A thermal management system for a fuel cell engine includes a controller, a fuel cell stack, a first water pump, a first heater, a first solenoid valve, a second solenoid valve, a deionizer, a second heater, a second water pump, an intercooler, and a water filter. The water inlet of the fuel cell stack is connected to an inlet pipe, and the water outlet of the fuel cell stack is connected to an outlet pipe. A third solenoid valve and an inlet temperature sensor are installed on the inlet pipe, and a fourth solenoid valve and an outlet temperature sensor are installed on the outlet pipe. The first solenoid valve, the first water pump, the first heater, and the second solenoid valve are sequentially arranged on the first pipe, the deionizer is arranged on the second pipe, and the second heater is arranged on the third pipe. The second water pump, the intercooler, and the water filter are sequentially arranged on the fourth pipeline. One end of the first pipeline is connected to the inlet pipeline below the third solenoid valve, and the other end of the first pipeline is connected to the outlet pipeline above the fourth solenoid valve. One end of the second, third, and fourth pipelines is connected to the inlet pipeline above the third solenoid valve, and the other end of the second, third, and fourth pipelines is connected to the outlet pipeline below the fourth solenoid valve. The first water pump, the first heater, the second water pump, each temperature sensor, and each solenoid valve are electrically connected to the controller.

[0007] Preferably, it further includes an electronic thermostat and an electronic fan assembly, the electronic fan assembly including a radiator and an electronic fan, the electronic thermostat being disposed on the fourth pipe and located between the second water pump and the intercooler, the radiator being disposed on the fifth pipe, one end of the fifth pipe being connected to the electronic thermostat, and the other end of the fifth pipe being connected to the fourth pipe at a point located between the water filter and the intercooler; the electronic thermostat and the electronic fan assembly are respectively electrically connected to the controller.

[0008] Preferably, it also includes an expansion tank, the lower end of which is connected to the water outlet pipe below the fourth solenoid valve via a sixth pipe.

[0009] Preferably, one side of the expansion tank is connected to the degassing port of the radiator via an air pipe.

[0010] Preferably, the first heater is a water heater and the second heater is a hydrogen heater.

[0011] A control method for a thermal management system of a fuel cell engine includes the following steps:

[0012] Step S1: The controller obtains the ambient temperature through the ambient temperature sensor and the temperature of the cooling water after it leaves the stack through the stack outlet temperature sensor.

[0013] Step S2: The controller determines whether the engine meets the cold start conditions based on the ambient temperature and the temperature of the cooling water after it leaves the stack. If it does, proceed to step S3; otherwise, proceed to step S4.

[0014] Step S3: The controller controls the third and fourth solenoid valves to close, and the first and second solenoid valves to open. At the same time, it controls the first water pump and the first heater to work until the temperature of the cooling water before entering the stack and the temperature after exiting the stack do not meet the cold start conditions. Then, step S4 is executed.

[0015] Step S4: The controller controls the first and second solenoid valves to close, and the third and fourth solenoid valves to open. At the same time, it controls the second water pump, electronic thermostat, and electronic fan assembly to work until the temperature of the cooling water after leaving the stack reaches the preset temperature. Then, step S5 is executed.

[0016] Step S5: The controller adjusts the operating parameters of the above components in real time according to the temperature difference between the temperature of the cooling water before entering the stack and the temperature after exiting the stack, so that the temperature of the cooling water after exiting the stack is maintained at the preset temperature, thereby keeping the thermal management system stable.

[0017] Preferably, in step S2, the cold start condition is that the ambient temperature is lower than the first set temperature, and the temperature of the cooling water after it leaves the stack is lower than the second set temperature.

[0018] Preferably, the preset temperature is between 80°C and 95°C; the first set temperature and the second set temperature are both between 0°C and 30°C.

[0019] The beneficial effects of this invention are as follows:

[0020] The thermal management system for a fuel cell engine of the present invention, during engine cold start, controls the third and fourth solenoid valves to close, and the first and second solenoid valves to open, while simultaneously controlling the first water pump and the first heater to operate. This allows cooling water to circulate only through the first solenoid valve, the first water pump, the first heater, the second solenoid valve, and the fuel cell stack. As can be seen, compared with the prior art, the present invention has fewer components in the cold start circulation path, which can better reduce heat loss, thereby facilitating rapid heating of the fuel cell stack and effectively shortening the cold start time of the fuel cell engine.

[0021] The control method provided by this invention also has the above-mentioned beneficial effects. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly described below, and the specific embodiments of the present invention will be further described in detail with reference to the drawings, wherein...

[0023] Figure 1 This is a schematic diagram of an existing fuel cell thermal management system;

[0024] Figure 2 This is a schematic diagram of a fuel cell engine thermal management system provided in an embodiment of the present invention.

[0025] Marked in the attached diagram:

[0026] 1. Water supply tank; 2. Radiator; 3. Electrically controlled three-way valve; 4. Electric heater; 5. Temperature sensor one; 6. Temperature sensor two; 7. Deionization device; 8. Throttling valve; 9. Variable frequency water pump; 10. Particulate filter; 11. Variable frequency fan; 12. Controller; 13. Hydrogen fuel cell system.

[0027] 21. Fuel cell stack; 22. First water pump; 23. First heater; 24. Second water pump; 25. Electronic thermostat; 26. Expansion tank; 27. Second heater; 28. Deionizer; 29. ​​Intercooler; 30. Feed temperature sensor; 31. Output temperature sensor; 32. Water filter; 33. Electric fan; 34. Third solenoid valve; 35. Fourth solenoid valve; 36. First solenoid valve; 37. Second solenoid valve; 38. Controller; 39. Radiator. Detailed Implementation

[0028] To enable those skilled in the art to better understand the technical solution of the present invention, the present solution will be further described in detail below with reference to specific embodiments.

[0029] like Figure 2As shown, this embodiment of the invention provides a thermal management system for a fuel cell engine, which includes a controller 38, a fuel cell stack 21, a first water pump 22, a first heater 23, a first solenoid valve 36, a second solenoid valve 37, a deionizer 28, a second heater 27, a second water pump 24, an intercooler 29, and a water filter 32. The water inlet of the fuel cell stack 21 is connected to an inlet pipe, and the water outlet of the fuel cell stack is connected to an outlet pipe. A third solenoid valve 34 and a stack inlet temperature sensor 30 are installed on the inlet pipe, and a fourth solenoid valve 35 and a stack outlet temperature sensor 31 are installed on the outlet pipe. The first solenoid valve 36, the first water pump 22, the first heater 23, and the second solenoid valve 37 are sequentially arranged on the first pipe, and the deionizer is arranged... On the second pipeline, the second heater is disposed on the third pipeline, and the second water pump, the intercooler, and the water filter are disposed sequentially on the fourth pipeline. One end of the first pipeline is connected to the inlet pipeline below the third solenoid valve, and the other end of the first pipeline is connected to the outlet pipeline above the fourth solenoid valve. One end of the second, third, and fourth pipelines is respectively connected to the inlet pipeline above the third solenoid valve, and the other end of the second, third, and fourth pipelines is respectively connected to the outlet pipeline below the fourth solenoid valve. The first water pump, the first heater, the second water pump, each temperature sensor, and each solenoid valve are electrically connected to the controller 38.

[0030] The fuel cell engine thermal management system provided in this embodiment of the invention controls the third solenoid valve 34 and the fourth solenoid valve 35 to close and the first solenoid valve 36 and the second solenoid valve 37 to open during engine cold start. At the same time, it controls the first water pump 22 and the first heater 23 to work, so that the cooling water only needs to circulate through the first solenoid valve, the first water pump, the first heater, the second solenoid valve and the fuel cell stack 21. It can be seen that compared with the prior art, the present invention has fewer components in the cold start circulation path, which can better reduce heat loss, thereby facilitating the rapid heating of the fuel cell stack and effectively shortening the cold start time of the fuel cell engine.

[0031] Furthermore, the fuel cell engine thermal management system also includes an electronic thermostat 25 and an electric fan assembly. The electric fan assembly includes a radiator 39 and an electric fan 33. The electronic thermostat 25 is disposed on the fourth pipeline and located between the second water pump and the intercooler. The radiator 39 is disposed on the fifth pipeline. One end of the fifth pipeline is connected to the electronic thermostat, and the other end of the fifth pipeline connects to the fourth pipeline between the water filter and the intercooler 29. The electronic thermostat and the electric fan are electrically connected to the controller. Preferably, the electronic thermostat communicates with the controller via a CAN bus. The controller sends an angle control target value to the electronic thermostat via the CAN bus, causing the actuator valve inside the electronic thermostat to respond according to the angle control target value. The actuator valve automatically rotates to the target value, and the real-time operating status of the electronic thermostat is fed back to the controller via the CAN bus. It is understandable that when the electronic thermostat has an angle control target value of 0°, all the coolant passes through the intercooler; when the electronic thermostat has an angle control target value of 90°, all the coolant passes through the radiator of the electric fan assembly; when the electronic thermostat has an angle control value between 0° and 90°, part of the coolant passes through the intercooler and the other part passes through the radiator of the electric fan assembly.

[0032] Specifically, the thermal management system of the fuel cell engine also includes an expansion tank 26, the lower end of which is connected to the outlet pipe below the fourth solenoid valve 35 via a sixth pipe.

[0033] Preferably, one side of the expansion tank 26 is connected to the degassing port of the radiator 39 via an air pipe, thus allowing the expansion tank to both replenish water in the water supply line and degas the radiator. It is understood that the degassing port of the radiator 39 is generally located at the upper end of the radiator. When cooling water flows through the fifth pipeline, air bubbles in the pipeline will flow from its degassing port through the air pipe into the expansion tank, and then be degassed through the expansion tank's degassing port. The electric fan is used to dissipate heat from the radiator. Preferably, the first water pump is a low-pressure electric water pump, and the second water pump is a high-pressure electric water pump, to better meet the usage requirements of both pumps and avoid waste. The controller can control the first water pump and the electric fan via PWM, and control the first heater, the second water pump, and the electronic thermostat via a CAN bus.

[0034] Specifically, the first heater 23 is a water heater, and the second heater 27 is a hydrogen heater. It can be understood that the water heater is primarily used to heat and de-ice the fuel cell stack during low-temperature cold starts, preventing the stored water in the stack from freezing at low temperatures, which could damage the membrane electrode assembly and affect the chemical reaction. The hydrogen heater can heat the depressurized, low-temperature hydrogen, improving reaction efficiency. The stack entry temperature sensor is used to obtain the temperature of the cooling water before it enters the stack, i.e., the stack entry water temperature.

[0035] The present invention also provides a control method for a thermal management system of a fuel cell engine, comprising the following steps:

[0036] Step S1: The controller 38 obtains the ambient temperature through the ambient temperature sensor and the temperature of the cooling water after it leaves the stack through the stack temperature sensor 31. It can be understood that the ambient temperature sensor is set at the front of the vehicle to collect the temperature of the external environment.

[0037] Step S2: The controller determines whether the engine meets the cold start conditions based on the ambient temperature and the temperature of the cooling water after it leaves the stack. If it does, proceed to step S3; otherwise, proceed to step S4.

[0038] Step S3: The controller controls the third solenoid valve 34 and the fourth solenoid valve 35 to close, and the first solenoid valve 36 and the second solenoid valve 37 to open. At the same time, it controls the first water pump 22 and the first heater 23 to work until the temperature of the cooling water before entering the stack and the temperature after leaving the stack do not meet the cold start conditions, and then executes step S4.

[0039] Step S4: The controller closes the first and second solenoid valves and opens the third and fourth solenoid valves. At the same time, it controls the second water pump, electronic thermostat 25, and electronic fan to work until the temperature of the cooling water after leaving the stack reaches the preset temperature. Then, step S5 is executed. Preferably, the preset temperature is 80°C to 95°C, which is usually specified in the manufacturer's instructions. The preset temperature is related to the materials and manufacturing process of the fuel cell stack and varies from manufacturer to manufacturer.

[0040] Step S5: The controller adjusts the operating parameters of the above components in real time according to the temperature difference between the temperature of the cooling water before entering the stack and the temperature after exiting the stack, so that the temperature of the cooling water after exiting the stack is maintained at the preset temperature, thereby keeping the thermal management system stable.

[0041] Understandably, after the third solenoid valve 34 and the fourth solenoid valve 35 are opened, the hydrogen heater and deionizer are always in operation; the dotted line in the figure represents the electrical control circuit.

[0042] Specifically, in step S2, the cold start condition is that the ambient temperature is lower than the first set temperature and the temperature of the cooling water after exiting the reactor is lower than the second set temperature. The first set temperature can be denoted as T1 and the second set temperature as T2. Preferably, the range of T1 and T2 is 0°C to 30°C, which can be selected according to requirements; usually, the value of T2 is greater than that of T1.

[0043] In one specific embodiment, if the ambient temperature is <T1 and the temperature of the cooling water after exiting the fuel cell stack (i.e., the fuel cell stack outlet water temperature) is <T2, the engine enters a low-temperature cold start mode. At this time, the controller closes the third solenoid valve 34 and the fourth solenoid valve 35, and opens the first solenoid valve 36 and the second solenoid valve 37. Simultaneously, the controller operates the first water pump and controls its speed, and also controls the water heater to start operating and control its power, so as to rapidly heat the fuel cell stack and enable it to reach a high temperature quickly. If the ambient temperature is ≥T1 and the fuel cell stack outlet water temperature is ≥T2, the engine switches to a normal start mode. At this time, the controller controls the third solenoid valve... 34. The fourth solenoid valve 35 opens, simultaneously controlling the second water pump, electronic thermostat 25, and electric fan to operate. The first solenoid valve 36 and the second solenoid valve 37 close, and the first water pump and water heater stop working. When the fuel cell stack outlet water temperature reaches the preset temperature, it enters the normal operation mode. The controller adjusts the operating parameters of each component in real time, such as the target control value of the opening angle of the electronic thermostat, the output power of the second water pump, and the speed of the electric fan, based on the real-time temperature difference between the fuel cell stack inlet water temperature and the fuel cell stack outlet water temperature, so as to keep the fuel cell stack outlet water temperature at the preset temperature, thereby maintaining the stability of the thermal management system and the normal output of engine performance.

[0044] For control methods in other situations where cold start conditions are not met, such as when the ambient temperature is <T1 but the fuel cell outlet water temperature is ≥T2 during the start-up phase, after the vehicle starts and warms up, when it stops and starts again, the fuel cell outlet water temperature will be >Ambient temperature. In this case, it can be determined as starting in normal mode. However, if the ambient temperature is ≥T1 and the fuel cell outlet water temperature is <T2, this generally will not occur. If it does occur, the thermal management system can report an error. Since this application is a low-temperature cold start control method, control methods for other situations where cold start conditions are not met can also use existing methods or be designed independently. This is not the focus of this application and will not be elaborated here.

[0045] Table 1. Water storage capacity of each component in the thermal management system

[0046]

[0047] As shown in Table 1, the unit of water volume is liters (L). The water storage capacity in a typical fuel cell stack is approximately 7L. Based on the empirical formulas Q = c * m * ΔT and W = c * m * ΔT * t, where ΔT is the allowable temperature rise during cooling water circulation, taken as 6–12℃ (the temperature difference between inlet and outlet water must be ≤10℃); m is the specific gravity of the medium, such as water, which can be approximated as M = 1000 kg / m³. 3c—specific heat of the medium, such as water, which can be approximated as C = 3.5 kJ / kg·℃; W—work, in J; T—time, in s; Q—heat generated by the fuel cell system that the cooling water needs to remove. When the medium and temperature rise are the same, heating a larger mass of the medium requires more energy. Using this invention, only the first water pump, the first heater, and the water stored in the fuel cell stack need to be heated. Under the same medium, the same temperature rise, and the same energy, heating to the required temperature for cold start of the fuel cell stack can save more than half the time, thus saving cold start time.

[0048] The present invention has the following beneficial effects:

[0049] 1) A dual-pump, multi-circulation water circuit thermal management system, represented by low-pressure and high-pressure water pumps, has been established. It can control the switching combination of various components to achieve different working cycle modes according to different functional modes and thermal management requirements, and accurately control the thermal management output of the system to reduce unnecessary heat waste in the circulation circuit, so as to achieve rapid heating of the fuel cell stack and shorten the engine's low-temperature cold start time.

[0050] 2) Different functional mode combinations, such as low temperature cold start control, low temperature hot start control, normal temperature start control, over-temperature protection control, shutdown control, and fault shutdown control, etc., in each mode, the actuators, namely high-pressure water pump, low-pressure water pump, electric fan, and water heater, respond differently, thereby saving energy and meeting the needs of the system, ensuring the reasonable and timely operation of each component, reducing unnecessary energy consumption, and the combination of multiple circulation paths can coordinate the heating and cooling needs of different water paths in specific scenarios, thereby bringing a more efficient heat utilization rate and reducing the energy consumption of the whole vehicle.

[0051] 3) By switching between different working cycle modes, the number of components in the system cooling water circulation circuit is reduced, the water resistance of the circulation circuit is lowered, and high and low pressure water pumps are used in conjunction to meet the thermal management requirements of high-power fuel cell engines during low-temperature cold start-up.

[0052] 4) The control system used in this method has fewer inputs, simpler control logic, and higher execution efficiency of the controlled components, resulting in a smaller computational load in the system's operational model, faster response speed of the controlled components, and higher control accuracy.

[0053] The above are merely preferred embodiments of the present invention. It should be noted that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. Moreover, after reading the contents of the present invention, those skilled in the art can make various modifications or alterations to the present invention, and these equivalent forms also fall within the scope defined by the appended claims.

Claims

1. A thermal management system for a fuel cell engine, characterized in that, It includes a controller, a fuel cell stack, a first water pump, a first heater, a first solenoid valve, a second solenoid valve, a deionizer, a second heater, a second water pump, an intercooler, and a water filter. The water inlet of the fuel cell stack is connected to an inlet pipe, and the water outlet of the fuel cell stack is connected to an outlet pipe. A third solenoid valve and a stack inlet temperature sensor are installed on the inlet pipe, and a fourth solenoid valve and a stack outlet temperature sensor are installed on the outlet pipe. The first solenoid valve, the first water pump, the first heater, and the second solenoid valve are sequentially arranged on the first pipe, the deionizer is arranged on the second pipe, the second heater is arranged on the third pipe, and the second water pump, the intercooler, and the water filter are sequentially arranged on the fourth pipe. One end of the first pipe is connected to the inlet pipe below the third solenoid valve, and the other end of the first pipe is connected to the outlet pipe above the fourth solenoid valve. One end of the second pipe, the third pipe, and the fourth pipe is connected to the inlet pipe above the third solenoid valve, and the other end of the second pipe, the third pipe, and the fourth pipe is connected to the outlet pipe below the fourth solenoid valve; the first water pump, the first heater, the second water pump, each of the temperature sensors, and each of the solenoid valves are electrically connected to the controller. It also includes an electronic thermostat and an electronic fan assembly. The electronic fan assembly includes a radiator and an electronic fan. The electronic thermostat is disposed on the fourth pipe and located between the second water pump and the intercooler. The radiator is disposed on the fifth pipe. One end of the fifth pipe is connected to the electronic thermostat, and the other end of the fifth pipe is connected to the fourth pipe between the water filter and the intercooler. The electronic thermostat and the electronic fan assembly are electrically connected to the controller. The electronic thermostat communicates with the controller via the CAN bus. The controller sends the angle control target value to the electronic thermostat via the CAN bus, causing the actuator valve inside the electronic thermostat to respond according to the angle control target value. When the angle control target value of the electronic thermostat is 0°, all the cooling water passes through the intercooler. When the angle control target value of the electronic thermostat is 90°, all the cooling water passes through the radiator of the electric fan assembly. When the angle control value of the electronic thermostat is greater than 0° and less than 90°, part of the cooling water passes through the intercooler and the other part passes through the radiator in the electric fan assembly. It also includes an expansion tank, the lower end of which is connected to the outlet pipe below the fourth solenoid valve via a sixth pipe.

2. The fuel cell engine thermal management system according to claim 1, characterized in that, One side of the expansion tank is connected to the degassing port of the radiator via an air pipe.

3. The fuel cell engine thermal management system according to claim 1, characterized in that, The first heater is a water heater, and the second heater is a hydrogen heater.

4. A control method for the thermal management system of a fuel cell engine as described in claim 1, characterized in that, It includes the following steps: Step S1: The controller obtains the ambient temperature through the ambient temperature sensor and the temperature of the cooling water after it leaves the stack through the stack outlet temperature sensor. Step S2: The controller determines whether the engine meets the cold start conditions based on the ambient temperature and the temperature of the cooling water after it leaves the stack. If it does, proceed to step S3; otherwise, proceed to step S4. Step S3: The controller controls the third and fourth solenoid valves to close, and the first and second solenoid valves to open. At the same time, it controls the first water pump and the first heater to work until the temperature of the cooling water before entering the stack and the temperature after exiting the stack do not meet the cold start conditions. Then, step S4 is executed. Step S4: The controller controls the first and second solenoid valves to close, and the third and fourth solenoid valves to open. At the same time, it controls the second water pump, electronic thermostat, and electronic fan assembly to work until the temperature of the cooling water after leaving the stack reaches the preset temperature. Then, step S5 is executed. Step S5: The controller adjusts the operating parameters of the above components in real time according to the temperature difference between the temperature of the cooling water before entering the stack and the temperature after exiting the stack, so that the temperature of the cooling water after exiting the stack is maintained at the preset temperature, thereby keeping the thermal management system stable. In step S2, the cold start condition is that the ambient temperature is lower than the first set temperature and the temperature of the cooling water after it leaves the stack is lower than the second set temperature.

5. The control method for a fuel cell engine thermal management system according to claim 4, characterized in that, The preset temperature is between 80℃ and 95℃; the first and second set temperatures are both between 0℃ and 30℃.

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