Temperature control method of fuel cell system and fuel cell system

Abstract

The invention relates to the technical field of fuel cell systems, and particularly discloses a temperature control method of a fuel cell system and the fuel cell system.The temperature control method of the fuel cell system comprises the steps that the required temperature of an electric pile cathode outlet is set; determining the cathode enthalpy difference of the galvanic pile based on the unit time generating capacity of the galvanic pile, the unit time heat dissipating capacity of the galvanic pile and the anode enthalpy difference of the galvanic pile; determining a required enthalpy value of the stack cathode outlet based on the required temperature of the stack cathode outlet; determining the required enthalpy value of the cathode inlet of the electric pile based on the cathode enthalpy difference of the electric pile and the required enthalpy value of the cathode outlet of the electric pile; determining the feed-forward temperature of the cathode inlet of the galvanic pile based on the required enthalpy value of the cathode inlet of the galvanic pile, and taking the feed-forward temperature of the cathode inlet of the galvanic pile as the execution temperature; and the temperature of the air reaches the execution temperature and is input to the cathode inlet of the electric pile, so that feed-forward regulation is realized, and compared with an existing mode of PID feedback regulation, the time required by regulation can be effectively saved, and the regulation efficiency is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cell systems, and in particular, to a temperature control method for a fuel cell system and a fuel cell system. Background Art

[0002] During the actual use of a fuel cell system, in order to ensure its efficient power generation, sometimes it is necessary to make the outlet temperature of the stack reach a certain range. However, this easily leads to a mismatch between the actual temperature at the outlet of the stack and the required temperature at the outlet of the stack. At this time, it is necessary to adjust the outlet temperature of the stack.

[0003] In the prior art, as disclosed in a previous patent with the application number CN202310650795.X, a temperature control method for a fuel cell system is disclosed. In this method, when the operating temperature of the fuel cell system is too high, the valve - intercooler PID feedback controller is used to adjust the fuel cell system to operate within the limited thermal safety temperature range, thereby ensuring the thermal safety of the fuel cell system. However, the adjustment efficiency of the feedback adjustment is relatively low, and there is a time delay phenomenon between detecting the deviation and completing the correction. For a fuel cell system that requires rapid response, this delay is likely to cause adverse effects. Summary of the Invention

[0004] The purpose of the present invention is to provide a temperature control method for a fuel cell system and a fuel cell system, so as to solve the problem that the temperature control of the existing fuel cell system uses feedback adjustment, which has a time delay phenomenon and is likely to cause adverse effects on a fuel cell system that requires rapid response.

[0005] On the one hand, the present invention provides a temperature control method for a fuel cell system. The fuel cell system includes at least one stack. The temperature control method of the fuel cell system includes a precise adjustment method. The precise adjustment method includes feed - forward adjustment. The feed - forward adjustment includes:

[0006] Setting the required temperature at the cathode outlet of the stack;

[0007] Obtaining the actual temperature at the cathode outlet of the stack;

[0008] When the required temperature at the cathode outlet of the stack is not equal to the actual temperature at the cathode outlet of the stack, obtaining the performance parameters of the stack. The performance parameters of the stack include the power generation per unit time of the stack, the heat dissipation per unit time of the stack, and the anode enthalpy difference of the stack. The anode enthalpy difference of the stack is the enthalpy difference between the anode inlet and the anode outlet of the stack;

[0009] Determine the cathode enthalpy difference of the fuel cell stack based on the power generation per unit time of the stack, the heat dissipation per unit time of the stack, and the anode enthalpy difference of the stack. The cathode enthalpy difference of the stack is the enthalpy difference between the cathode inlet and the cathode outlet of the stack;

[0010] Determine the required enthalpy value at the cathode outlet of the stack based on the required temperature at the cathode outlet of the stack;

[0011] Determine the required enthalpy value at the cathode inlet of the stack based on the cathode enthalpy difference of the stack and the required enthalpy value at the cathode outlet of the stack;

[0012] Determine the feedforward temperature at the cathode inlet of the stack based on the required enthalpy value at the cathode inlet of the stack, and use the feedforward temperature at the cathode inlet of the stack as the execution temperature;

[0013] Adjust the temperature of the air to the execution temperature and input it to the cathode inlet of the stack.

[0014] As a preferred technical solution of the temperature control method for the fuel cell system, the method for obtaining the power generation per unit time of the stack includes:

[0015] Obtain the output voltage and the output current of the stack;

[0016] The power generation per unit time of the stack is equal to the product of the output voltage and the output current of the stack.

[0017] As a preferred technical solution of the temperature control method for the fuel cell system, the method for obtaining the heat dissipation per unit time of the stack includes:

[0018] Obtain the mass of the stack and the temperature change per unit time of the stack;

[0019] Determine the heat dissipation per unit time of the stack based on the mass of the stack and the temperature change per unit time of the stack.

[0020] As a preferred technical solution of the temperature control method for the fuel cell system, the method for obtaining the anode enthalpy difference of the stack includes:

[0021] Judge whether a reformer is connected to the anode inlet of the stack;

[0022] If so, obtain the actual temperature at the outlet of the reformer, the oxygen-carbon ratio of the gas entering the anode of the stack, the actual temperature at the anode inlet of the stack, and the actual temperature at the anode outlet of the stack;

[0023] Determine the anode enthalpy difference of the stack based on the actual temperature at the outlet of the reformer, the oxygen-carbon ratio, the actual temperature at the anode inlet of the stack, and the actual temperature at the anode outlet of the stack.

[0024] As a preferred technical solution of the temperature control method for a fuel cell system, if a reformer is not connected to the anode inlet of the fuel cell stack, obtain the composition of the fuel gas entering the anode of the fuel cell stack, the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack, the actual temperature at the anode inlet of the fuel cell stack, and the actual temperature at the anode outlet of the fuel cell stack;

[0025] Determine the anode enthalpy difference of the fuel cell stack based on the composition of the fuel gas at the anode of the fuel cell stack, the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack, the actual temperature at the anode inlet of the fuel cell stack, and the actual temperature at the anode outlet of the fuel cell stack.

[0026] As a preferred technical solution of the temperature control method for a fuel cell system, the precise adjustment method further includes a feedback adjustment following the feedforward adjustment, and the feedback adjustment includes:

[0027] Obtain the actual temperature at the cathode outlet of the fuel cell stack;

[0028] Compare the actual temperature at the cathode outlet of the fuel cell stack with the required temperature at the cathode outlet of the fuel cell stack;

[0029] If the actual temperature at the cathode outlet of the fuel cell stack is greater than the required temperature at the cathode outlet of the fuel cell stack;

[0030] Then reduce the execution temperature by a set value on the existing basis;

[0031] Adjust the temperature of the air to the execution temperature and input it into the cathode inlet of the fuel cell stack.

[0032] As a preferred technical solution of the temperature control method for a fuel cell system, if the actual temperature at the cathode outlet of the fuel cell stack is less than the required temperature at the cathode outlet of the fuel cell stack;

[0033] Then increase the execution temperature by a set value on the existing basis;

[0034] Adjust the temperature of the air to the execution temperature and input it into the cathode inlet of the fuel cell stack.

[0035] As a preferred technical solution of the temperature control method for a fuel cell system, the temperature control method of the fuel cell system includes a range adjustment method, and the range adjustment method includes:

[0036] Obtain the actual temperature at the outlet of the fuel cell stack, where the actual temperature at the outlet of the fuel cell stack is the actual temperature at the anode outlet of the fuel cell stack or the actual temperature at the cathode outlet of the fuel cell stack;

[0037] Judge whether the actual temperature at the outlet of the fuel cell stack exceeds the safety threshold;

[0038] If so, reduce the power generation power of the fuel cell stack by a preset power value, and repeat the step of obtaining the actual temperature at the outlet of the fuel cell stack.

[0039] On the other hand, the present invention provides a fuel cell system for implementing the temperature control method of the fuel cell system described in any one of the embodiments. The fuel cell system includes:

[0040] Two stacks, namely a primary stack and a secondary stack;

[0041] A reformer connected to the anode inlet of the primary stack;

[0042] An air supplement mixer disposed between the primary stack and the secondary stack. The air supplement mixer is configured to mix the tail gas output from the anode outlet of the primary stack with the supplemented fresh fuel gas and then deliver the mixture to the anode inlet of the secondary stack;

[0043] A first mixer for mixing the heated hot air and cold air and then delivering the mixture to the cathode inlet of the primary stack;

[0044] A second mixer for mixing the tail gas output from the anode outlet of the primary stack and cold air and then delivering the mixture to the cathode inlet of the secondary stack.

[0045] As a preferred technical solution of the fuel cell system, the fuel cell system further includes:

[0046] A burner connected to the anode outlet and the cathode outlet of the secondary stack;

[0047] An air preheater. The heat generated by the combustion of the burner is used to supply the air preheater, and the air preheater is configured to heat the cold air and then deliver it to the first mixer.

[0048] The beneficial effects of the present invention are:

[0049] The present invention provides a temperature control method for a fuel cell system and a fuel cell system. The temperature control method for the fuel cell system comprises the following steps: setting a required temperature at a cathode outlet of a stack; obtaining an actual temperature at a cathode outlet of the stack; obtaining a performance parameter of the stack when the required temperature at the cathode outlet of the stack is not equal to the actual temperature at the cathode outlet of the stack; determining a cathode enthalpy difference of the stack based on the power generation per unit time of the stack, the heat dissipation per unit time of the stack, and an anode enthalpy difference of the stack; determining a required enthalpy value at the cathode outlet of the stack based on the required temperature at the cathode outlet of the stack; determining a required enthalpy value at the cathode inlet of the stack based on the cathode enthalpy difference of the stack and the required enthalpy value at the cathode outlet of the stack; determining a feedforward temperature at the cathode inlet of the stack based on the required enthalpy value at the cathode inlet of the stack, and using the feedforward temperature at the cathode inlet of the stack as an execution temperature; and making the temperature of the air reach the execution temperature and inputting it into the cathode inlet of the stack, thereby realizing feedforward regulation. Since the feedforward temperature at the cathode inlet of the stack is calculated based on the required temperature at the cathode outlet of the stack, when the air enters the cathode of the stack at the feedforward temperature, it can ensure that the temperature at the cathode outlet of the stack is equal to or very close to the required temperature at the cathode outlet of the stack. Compared with the PID feedback regulation method in the prior art, it can effectively save the time required for regulation and improve the regulation efficiency, which is suitable for fuel cell systems that require fast response. Brief Description of the Figures

[0050] Figure 1 is the process of the temperature control method of the fuel cell system in an embodiment of the present invention Figure 1 ;

[0051] Figure 2 is the process of the temperature control method of the fuel cell system in an embodiment of the present invention Figure 2 ;

[0052] Figure 3 is the process of the temperature control method of the fuel cell system in an embodiment of the present invention Figure 2 ;

[0053] Figure 4 is a schematic diagram of the structure of the fuel cell system in an embodiment of the present invention.

[0054] In the picture:

[0055] 1. Steam generator; 2. Reformer; 3. Primary stack; 4. Heat exchanger; 5. Tail gas cooler; 6. Air supply mixer; 7. Secondary stack; 8. Condenser; 9. Water separator; 10. Water pump; 11. Water tank; 12. Air preheater; 13. Burner; 14. Diverter; 15. First mixer; 16. Second mixer. Specific implementation method

[0056] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0057] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings. It is only for the convenience of describing the present invention and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention. In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance. Among them, the terms "first position" and "second position" are two different positions. Moreover, the first feature being "above", "over" and "on" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature has a higher horizontal height than the second feature. The first feature being "below", "under" and "beneath" the second feature includes the first feature being directly below and obliquely below the second feature, or simply indicating that the first feature has a lower horizontal height than the second feature.

[0058] In the description of the present invention, it should be noted that unless otherwise clearly specified and limited, the terms "mounted", "connected" and "coupled" shall be construed in a broad sense. For example, it may be a fixed connection, a detachable connection, or an integral connection; it may be a mechanical connection or an electrical connection; it may be directly connected or indirectly connected through an intermediate medium, and it may be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0059] The embodiments of the present invention will be described in detail below. The examples of the embodiments are shown in the accompanying drawings, in which the same or similar reference numerals indicate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary and are only used to explain the present invention and should not be construed as a limitation of the present invention.

[0060] Embodiment 1

[0061] During the actual use of a fuel cell system, to ensure its efficient power generation, sometimes it is necessary to keep the outlet temperature of the stack within a certain range. However, this easily leads to a mismatch between the actual temperature at the stack outlet and the required temperature at the stack outlet. At this time, it is necessary to adjust the outlet temperature of the stack. In the prior art, the temperature is adjusted by means of feedback regulation. The regulation efficiency of feedback regulation is relatively low, and there is a time delay phenomenon between detecting the deviation and completing the correction. For a fuel cell system that requires rapid response, this delay is likely to cause adverse effects.

[0062] In view of this, the present embodiment provides a temperature control method for a fuel cell system to solve the above problems. The temperature control method for the fuel cell system can be implemented by the fuel cell system. Among them, the fuel cell system is specifically a solid oxide fuel cell system. A solid oxide fuel cell system is a fully solid-state chemical power generation device that directly and efficiently converts the chemical energy stored in fuel and oxidant into electrical energy at medium and high temperatures in an environmentally friendly manner, and has the characteristics of high energy density and high efficiency.

[0063] The temperature control method for the fuel cell system provided in the present embodiment includes a precise adjustment method and a range adjustment method. Among them, the precise adjustment method includes feedforward adjustment and feedback adjustment. As Figure 1 shown, the feedforward adjustment includes:

[0064] S100: Set the required temperature at the cathode outlet of the stack.

[0065] Among them, the required temperature at the cathode outlet of the stack can be set according to the actual needs during the operation of the fuel cell. For example, when the user hopes that the stack of the fuel cell system can have a high power generation efficiency, at this time, the required temperature at the cathode outlet of the stack needs to be set close to the temperature upper limit.

[0066] S110: Obtain the actual temperature at the cathode outlet of the stack.

[0067] Specifically, the actual temperature at the cathode outlet of the stack can be detected by a temperature sensor.

[0068] S120: Determine whether the required temperature at the cathode outlet of the stack is equal to the actual temperature at the cathode outlet of the stack.

[0069] When the required temperature at the cathode outlet of the stack is not equal to the actual temperature at the cathode outlet of the stack, execute S130. When the required temperature at the cathode outlet of the stack is equal to the actual temperature at the cathode outlet of the stack, the process ends.

[0070] S130: Obtain the performance parameters of the stack.

[0071] Among them, the performance parameters of the stack include the power generation amount per unit time of the stack, the heat dissipation amount per unit time of the stack, and the anode enthalpy difference of the stack. The anode enthalpy difference of the stack is the enthalpy difference between the anode inlet and the anode outlet of the stack.

[0072] Specifically, the method for obtaining the power generation amount per unit time of the stack includes: obtaining the output voltage and the output current of the stack; the power generation amount per unit time of the stack is equal to the product of the output voltage and the output current of the stack.

[0073] Among them, the output voltage of the stack can be detected by a voltmeter, and the output current of the stack can be detected by an ammeter.

[0074] The method for obtaining the heat dissipation amount per unit time of the stack includes: obtaining the mass of the stack and the temperature change amount per unit time of the stack; determining the heat dissipation amount per unit time of the stack based on the mass of the stack and the temperature change amount per unit time of the stack.

[0075] Among them, the mass of the stack is determined by the model of the stack and is a fixed value. The temperature change amount per unit time of the stack can be calculated by obtaining the difference between the temperature values detected by the temperature measuring device before and after per unit time of the stack. Map1 of the mass of the stack, the temperature change amount per unit time of the stack, and the heat dissipation amount per unit time of the stack can be pre-stored in the controller. The mass of the stack and the temperature change amount per unit time of the stack obtained can be input into map1 to obtain the heat dissipation amount per unit time of the stack. Among them, map1 can be obtained through a large number of previous experiments.

[0076] The method for obtaining the anode enthalpy difference of the stack is divided into two cases: when a reformer is connected to the front end of the anode inlet of the stack and when it is not connected. It should be noted that when the fuel cell system includes one stack, a reformer is usually set at the front end of the anode inlet of the stack; when the fuel cell system includes multiple stacks, a reformer is usually set at the front end of the anode inlet of the first-stage stack, while a reformer may or may not be set at the front end of the anode inlet of the second-stage stack and the stacks after the second-stage stack. For example, a device for supplementing fuel gas can be set. Therefore, it is necessary to explain in two cases: when a reformer is connected to the front end of the anode inlet of the stack and when it is not connected.

[0077] When a reformer is connected to the anode inlet of the stack, obtain the actual temperature at the outlet of the reformer, the oxygen-carbon ratio of the gas entering the anode of the stack, the actual temperature at the anode inlet of the stack, and the actual temperature at the anode outlet of the stack; determine the anode enthalpy difference of the stack based on the actual temperature at the outlet of the reformer, the oxygen-carbon ratio, the actual temperature at the anode inlet of the stack, and the actual temperature at the anode outlet of the stack.

[0078] Among them, the actual temperature at the outlet of the reformer, the oxygen-to-carbon ratio of the gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, and the actual temperature at the outlet of the anode of the fuel cell stack can all be detected and obtained by corresponding sensors. A map2 of the actual temperature at the outlet of the reformer, the oxygen-to-carbon ratio of the gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, the actual temperature at the outlet of the anode of the fuel cell stack, and the enthalpy difference of the anode of the fuel cell stack can be pre-stored in the controller. The actual temperature at the outlet of the reformer, the oxygen-to-carbon ratio of the gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, and the actual temperature at the outlet of the anode of the fuel cell stack obtained can be input into map2 to obtain the enthalpy difference of the anode of the fuel cell stack. Among them, map2 can be obtained through a large number of previous tests.

[0079] When the reformer is not connected to the inlet of the anode of the fuel cell stack, obtain the components of the fuel gas entering the anode of the fuel cell stack, the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, and the actual temperature at the outlet of the anode of the fuel cell stack; determine the enthalpy difference of the anode of the fuel cell stack based on the components of the fuel gas of the anode of the fuel cell stack, the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, and the actual temperature at the outlet of the anode of the fuel cell stack.

[0080] Among them, the components of the fuel gas of the anode of the fuel cell stack and the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack can both be detected and obtained by corresponding sensors. A map3 of the components of the fuel gas entering the anode of the fuel cell stack, the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, the actual temperature at the outlet of the anode of the fuel cell stack, and the enthalpy difference of the anode of the fuel cell stack can be pre-stored in the controller. The components of the fuel gas entering the anode of the fuel cell stack, the flow rate per unit time of the fuel gas entering the anode of the fuel cell stack, the actual temperature at the inlet of the anode of the fuel cell stack, and the actual temperature at the outlet of the anode of the fuel cell stack obtained can be input into map3 to obtain the enthalpy difference of the anode of the fuel cell stack. Among them, map3 can be obtained through a large number of previous tests.

[0081] S140: Determine the enthalpy difference of the cathode of the fuel cell stack based on the power generation per unit time of the fuel cell stack, the heat dissipation per unit time of the fuel cell stack, and the enthalpy difference of the anode of the fuel cell stack.

[0082] Among them, the enthalpy difference of the cathode of the fuel cell stack is the enthalpy difference between the inlet and the outlet of the cathode of the fuel cell stack.

[0083] Specifically, the sum of the power generation per unit time of the fuel cell stack and the heat dissipation per unit time of the fuel cell stack is equal to the sum of the enthalpy difference of the anode of the fuel cell stack and the enthalpy difference of the cathode of the fuel cell stack. Thus, the enthalpy difference of the cathode of the fuel cell stack = (the power generation per unit time of the fuel cell stack + the heat dissipation per unit time of the fuel cell stack - the enthalpy difference of the anode of the fuel cell stack).

[0084] S150: Determine the required enthalpy value at the outlet of the cathode of the fuel cell stack based on the required temperature at the outlet of the cathode of the fuel cell stack.

[0085] A map4 of the required temperature and the required enthalpy value at the cathode outlet of the stack is pre-stored in the controller. The required enthalpy value at the cathode outlet of the stack can be obtained by inputting the required temperature at the cathode outlet of the stack into map4. Among them, map4 can be obtained through a large number of previous experiments.

[0086] S160: Determine the required enthalpy value at the cathode inlet of the stack based on the enthalpy difference at the cathode of the stack and the required enthalpy value at the cathode outlet of the stack.

[0087] Specifically, the required enthalpy value at the cathode inlet of the stack = the required enthalpy value at the cathode outlet of the stack + the enthalpy difference at the cathode of the stack.

[0088] S170: Determine the feedforward temperature at the cathode inlet of the stack based on the required enthalpy value at the cathode inlet of the stack, and use the feedforward temperature at the cathode inlet of the stack as the execution temperature.

[0089] A map5 of the required enthalpy value at the cathode inlet of the stack and the feedforward temperature at the cathode inlet of the stack is pre-stored in the controller. The feedforward temperature at the cathode inlet of the stack can be obtained by inputting the required enthalpy value at the cathode inlet of the stack into map5. Among them, map5 can be obtained through a large number of previous experiments.

[0090] S180: Make the temperature of the air reach the execution temperature and input it into the cathode inlet of the stack.

[0091] Specifically, when the fuel cell system is running and the stack that needs to adjust the temperature at the cathode outlet to the required temperature is running, control the air to enter the cathode inlet of the stack at the execution temperature. Among them, the feedforward temperature at the cathode inlet of the stack is calculated based on the required temperature at the cathode outlet of the stack. When the air enters the cathode of the stack at this feedforward temperature, it can ensure that the temperature at the cathode outlet of the stack is equal to or very close to the required temperature at the cathode outlet of the stack. Compared with the existing PID feedback regulation method, it can effectively save the time required for regulation, improve the regulation efficiency, and is applicable to fuel cell systems that require fast response.

[0092] The temperature control method of the fuel cell system provided in this embodiment includes setting the required temperature at the cathode outlet of the stack; obtaining the actual temperature at the cathode outlet of the stack; when the required temperature at the cathode outlet of the stack is not equal to the actual temperature at the cathode outlet of the stack, obtaining the performance parameters of the stack; determining the cathode enthalpy difference of the stack based on the power generation per unit time of the stack, the heat dissipation per unit time of the stack, and the anode enthalpy difference of the stack; determining the required enthalpy value at the cathode outlet of the stack based on the required temperature at the cathode outlet of the stack; determining the required enthalpy value at the cathode inlet of the stack based on the cathode enthalpy difference of the stack and the required enthalpy value at the cathode outlet of the stack; determining the feed-forward temperature at the cathode inlet of the stack based on the required enthalpy value at the cathode inlet of the stack, and using the feed-forward temperature at the cathode inlet of the stack as the execution temperature; making the temperature of the air reach the execution temperature and inputting it to the cathode inlet of the stack, so as to achieve feed-forward regulation. Since the feed-forward temperature at the cathode inlet of the stack is calculated based on the required temperature at the cathode outlet of the stack, when the air enters the cathode of the stack at this feed-forward temperature, it can ensure that the temperature at the cathode outlet of the stack is equal to or very close to the required temperature at the cathode outlet of the stack. Compared with the PID feedback regulation method in the prior art, it can effectively save the time required for regulation and improve the regulation efficiency, and is applicable to fuel cell systems that require rapid response.

[0093] Optionally, please refer to Figure 2 , the precise adjustment method further includes a feedback adjustment after the feed-forward adjustment.

[0094] It can be understood that after the feed-forward adjustment is performed, although it is possible to make the actual temperature at the cathode outlet of the stack equal to the required temperature at the cathode outlet of the stack, it is also possible to make the actual temperature at the cathode outlet of the stack close to the required temperature at the cathode outlet of the stack. For the case where the actual temperature at the cathode outlet of the stack is close to the required temperature at the cathode outlet of the stack, it can be adjusted through feedback adjustment.

[0095] The feedback adjustment includes the following steps.

[0096] S200: Obtain the actual temperature at the cathode outlet of the stack.

[0097] S210: Compare the actual temperature at the cathode outlet of the stack with the required temperature at the cathode outlet of the stack.

[0098] If the actual temperature at the cathode outlet of the stack is greater than the required temperature at the cathode outlet of the stack, then execute S220; if the actual temperature at the cathode outlet of the stack is less than the required temperature at the cathode outlet of the stack, then execute S240; if the actual temperature at the cathode outlet of the stack is equal to the required temperature at the cathode outlet of the stack, then end.

[0099] S220: Reduce the execution temperature by a set value on the existing basis.

[0100] S230: Bring the temperature of the air to the execution temperature and input it into the cathode inlet of the stack.

[0101] S240: Increase the execution temperature by a set value on the existing basis.

[0102] S250: Bring the temperature of the air to the execution temperature and input it into the cathode inlet of the stack.

[0103] After steps S230 and S250, repeat S200.

[0104] Through feedback regulation, the magnitude of the execution temperature can be adjusted. Eventually, when the temperature of the air entering the cathode inlet of the stack is the execution temperature, the actual temperature at the cathode outlet of the stack is equal to the required temperature at the cathode outlet of the stack.

[0105] Optionally, the temperature control method of the fuel cell system further includes a range adjustment method. To ensure the operating performance and lifespan of the stack, the temperature at the stack outlet (cathode outlet of the stack, anode outlet of the stack) has upper and lower limit requirements. If the temperature is too high, the catalyst in the stack will be deactivated, causing stack degradation. If the temperature is too low, the stack cannot reach the optimal operating state. Therefore, when the temperature at the stack outlet exceeds the upper and lower limit requirements, it needs to be adjusted within the range. Among them, the range adjustment method is applicable when the temperature at the stack outlet is outside the upper and lower limit requirements, and quickly adjusts the temperature at the stack outlet to within the upper and lower limit requirements.

[0106] Specifically, please refer to Figure 3 , and the range adjustment method includes the following steps.

[0107] S300: Obtain the actual temperature at the stack outlet.

[0108] Among them, the actual temperature at the stack outlet is the actual temperature at the anode outlet of the stack or the actual temperature at the cathode outlet of the stack. Because a large amount of heat is released during the chemical reaction in the stack, the temperatures of the anode exhaust gas and the cathode exhaust gas of the stack are the same.

[0109] S310: Determine whether the actual temperature at the stack outlet exceeds the safety threshold.

[0110] The safety threshold here can be understood as the upper limit value.

[0111] If so, execute S320; if not, end.

[0112] S320: Reduce the power generation power of the stack by a preset power value and repeat the steps of S300.

[0113] Through the above steps S300 to S320, the actual temperature at the stack outlet can be made to be within the upper and lower limit ranges.

[0114] Embodiment 2

[0115] This embodiment provides a fuel cell system for implementing the temperature control method of the fuel cell system in the first embodiment above.

[0116] Please refer to Figure 4 , this fuel cell system includes two stacks. The two stacks are the primary stack 3 and the secondary stack 7 respectively. In other embodiments, the fuel cell system may also include one stack, or three or more stacks.

[0117] This fuel cell system further includes a gas replenishment mixer 6. The gas replenishment mixer 6 is arranged between the primary stack 3 and the secondary stack 7. The gas replenishment mixer 6 is used to mix the tail gas output from the anode outlet of the primary stack 3 with the supplemented fresh fuel gas and then transport it to the anode inlet of the secondary stack 7.

[0118] This fuel cell system further includes a steam generator 1 and a reformer 2. The reformer 2 is connected to the anode inlet of the primary stack 3. Among them, along the fuel flow path, the steam generator 1 and the reformer 2 are arranged in sequence. The steam generator 1 is used to introduce water and fuel (such as natural gas), and can promote the evaporation of water into water vapor and mix it with the fuel. After the mixed gas enters the reformer 2, a reforming reaction occurs in the reformer 2, and part of it generates hydrogen and carbon dioxide, and then is transported to the anode of the primary stack 3 to supply the reaction of the primary stack 3.

[0119] This fuel cell system includes a heat exchanger 4 and a tail gas cooler 5. The heat exchanger 4 is provided with a first heat exchange flow path and a second heat exchange flow path. The tail gas cooler 5 is provided with a first air flow path and a tail gas cooling flow path. One end of the first heat exchange flow path communicates with the anode outlet of the primary stack 3, and the other end of the first heat exchange flow path communicates with one end of the tail gas cooling flow path. The other end of the tail gas cooling flow path can communicate with the inlet of the gas replenishment mixer 6. The inlet of the gas replenishment mixer 6 is also used to input supplementary fuel gas. The outlet of the gas replenishment mixer 6 communicates with one end of the second heat exchange flow path, and the other end of the second heat exchange flow path communicates with the inlet of the secondary stack 7. The tail gas cooler 5 is used to heat the cold air to form hot air, and the hot air is used to supply the primary stack 3. The tail gas discharged from the anode outlet of the primary stack 3 has a relatively high temperature. The tail gas first enters the first heat exchange flow path of the heat exchanger 4 and exchanges heat with the fuel gas to enter the anode inlet of the secondary stack 7 in the heat exchanger 4. While raising the temperature of the fuel gas entering the anode inlet of the secondary stack 7, its own temperature is initially reduced (about to 400 °C), and then enters the tail gas cooling flow path of the tail gas cooler 5 to provide heat for part of the cold air finally transported to the primary stack 3, and its own temperature is reduced again (about 85 °C). In this way, the energy of the tail gas output from the anode outlet of the primary stack 3 can be effectively utilized, and the power generation efficiency of the fuel cell system can be improved.

[0120] The fuel cell system further includes a condenser 8 and a water separator 9 connected in series. The inlet of the condenser 8 is communicated with the exhaust gas cooling flow channel, and the gas outlet of the water separator 9 is communicated with the inlet of the air supplement mixer 6. With such an arrangement, the concentration of the fuel gas entering the secondary fuel cell stack 7 can be effectively increased; and since the exhaust gas discharged from the anode outlet of the primary fuel cell stack 3 has been cooled to about 85°C after two heat exchanges in the heat exchanger 4 and the exhaust gas cooler 5, when it enters the condenser 8, the heat exchange load of the condenser 8 can be effectively reduced, the heat carried away by the coolant is greatly reduced, the heat loss of the anode exhaust gas of the primary fuel cell stack 3 is reduced, and the power generation efficiency of the system is ensured.

[0121] The fuel cell system further includes a water pump 10 connected to the water outlet of the water separator 9 and a water tank 11 connected to the water pump 10. The water separated in the water separator 9 can be recycled to the water tank 11 through the water pump 10. Water resources can be effectively saved. Preferably, the water tank 11 is connected to the steam generator 1 and is used to supply water to the steam generator 1, so that the recycled water can be effectively utilized and external water supply is not required.

[0122] The fuel cell system further includes a first mixer 15 and a second mixer 16. The first mixer 15 is used to mix the heated hot air and cold air and then transport it to the cathode inlet of the primary fuel cell stack 3; the second mixer 16 is used to mix the exhaust gas output from the anode outlet of the primary fuel cell stack 3 and cold air and then transport it to the cathode inlet of the secondary fuel cell stack 7. Among them, the hot air mixed by the first mixer 15 is heated by the exhaust gas cooler 5.

[0123] The fuel cell system further includes a diverter 14. The inlet of the diverter 14 is used to introduce air. One outlet of the diverter 14 is communicated with the inlet of the first mixer 15, another outlet of the diverter 14 is communicated with the inlet of the second mixer 16, and still another outlet of the diverter 14 is also communicated with the first air flow channel. The first air flow channel is used to heat the cold air to form hot air and finally supply it to the first mixer 15, and the first mixer 15 mixes the cold air and supplies it to the primary fuel cell stack 3.

[0124] To improve the heating effect of the air, the fuel cell system further includes an air preheater 12 and a burner 13. The burner 13 is respectively connected to the anode outlet and the cathode outlet of the secondary fuel cell stack 7. The air preheater 12 is provided with a second air flow channel and an exhaust gas flow channel. The exhaust gas outlet of the burner 13 is communicated with the exhaust gas flow channel. The second air flow channel is communicated with the first air flow channel and is located downstream of the first air flow channel. A part of the cold air diverted by the diverter 14 can sequentially pass through the first air flow channel and the second air flow channel, so as to ensure that the temperature of the cold air rises to a relatively high level.

[0125] In addition, by adjusting the shunt ratio of the shunt 14 and the mixing ratio of the first mixer 15, the temperature of the air entering the cathode of the first fuel cell stack 3 can be adjusted, which is conducive to adjusting the temperature of the inlet air required by the cathode of the first fuel cell stack 3 to the required range, improving the durability of the first fuel cell stack 3, and avoiding the performance degradation of the first fuel cell stack 3. By adjusting the shunt ratio of the shunt 14 and the mixing ratio of the second mixer 16, the temperature of the air entering the cathode of the second fuel cell stack 7 can be adjusted, and then the temperature of the inlet air required by the cathode of the second fuel cell stack 7 can be adjusted to the required range, improving the durability of the second fuel cell stack 7, and avoiding the performance degradation of the second fuel cell stack 7. Among them, the adjustment of the shunt ratio of the shunt 14, the mixing ratio of the first mixer 15, and the mixing ratio of the second mixer 16 are prior arts and will not be elaborated here.

[0126] Optionally, the reformer 2 is provided with a reforming heat exchange flow channel. The first air flow channel, the second air flow channel, and the reforming heat exchange flow channel are connected in sequence, and the reforming heat exchange flow channel is connected to an inlet of the first mixer 15. Since the cold air heated by the exhaust gas cooler 5 and the air preheater 12 can have a relatively high temperature, the hot air can first flow through the reformer 2 to provide heat for the reformer 2 to ensure the smooth progress of the reforming reaction in the reformer 2, and then enter the first fuel cell stack 3 after being mixed with the cold air through the first mixer 15, so that the thermal energy of the air can be effectively utilized.

[0127] Optionally, the steam generator 1 is provided with a steam generation heat exchange flow channel, and the exhaust gas outlet of the air preheater 12 is connected to the steam generation heat exchange flow channel. With this setting, the exhaust gas flowing out from the exhaust gas flow channel of the air preheater 12 continues to enter the steam generation heat exchange flow channel of the steam generator 1 to provide heat for the steam generator 1 to ensure the normal operation of the steam generator 1, which can further improve the utilization rate of the energy generated by the combustion of the burner 13, and contribute to the normal operation of the air preheater 12. Moreover, the air preheater 12 does not need to rely on an external energy source, and the independence of the system can be maintained. Among them, when the exhaust gas is discharged from the steam generator 1, the temperature can be reduced to below 100°C.

[0128] In this embodiment, the tail gas cooler 5 and the air preheater 12 on the air side of the fuel cell system are reasonably arranged, which can effectively prevent the heat exchange efficiency of the air preheater 12 from being too high and reduce the design difficulty of the components of the air preheater 12. Specifically, the diverter 14 diverts the air into three paths. Among them, the main path sequentially flows through the tail gas cooler 5 and the air preheater 12, one side path flows to the first mixer 15, and the other side path flows to the second mixer 16. If the air in the main path directly enters the reformer 2 after being heated only by passing through the air preheater 12 and then enters the first mixer 15 from the reformer 2 to be mixed with the air in one side path and then enters the first-stage fuel cell stack 3 for power generation, at this time, it is required that the temperature of the air in the second air flow channel passing through the air preheater 12 rises from 30 °C to above 600 °C, and the heat exchange efficiency of the air preheater 12 needs to reach more than 90%. The design difficulty of the air preheater 12 is large. By adding the tail gas cooler 5 in front of the air preheater 12, the tail gas cooler 5 can preheat the air flowing through the first air flow channel to above 100 °C, increase the temperature of the air at the inlet of the second air flow channel entering the air preheater 12, thereby reducing the heat exchange efficiency of the air preheater 12 and reducing the design difficulty of the components of the air preheater 12.

[0129] As Figure 4 shown, for the fuel cell system provided in this embodiment, the main working process on the anode side is as follows: After natural gas and water are mixed, they are heated by the steam generator 1, then enter the reformer 2 to undergo a steam reforming reaction to produce hydrogen, then enter the anode of the first-stage fuel cell stack 3 for power generation, then are cooled by heat exchange through the heat exchanger 4 and the tail gas cooler 5 in sequence, then enter the condenser 8 for condensation, then enter the water separator 9 to remove water, so that the gas concentration is purified, then enter the gas supply mixer 6 and are mixed with the supplementary gas, are heated by heat exchange through the heat exchanger 4, enter the anode of the second-stage fuel cell stack 7 to continue power generation, then enter the burner 13 for combustion, the tail gas after combustion heats the flowing air through the air preheater 12, and finally enters the steam generator 1 to heat the mixture of gas and water and then is discharged from the system.

[0130] The main working process on the cathode side is as follows: The cold air is divided into three paths after entering the diverter 14. The air in the main path is sequentially heated by the tail gas cooler 5 and the air preheater 12. The heated hot air enters the reformer 2 to provide heat for the reforming reaction. The hot air output from the reformer 2 is mixed with the cold air bypassing in one path in the first mixer 15 and enters the cathode of the first-stage fuel cell stack 3. The hot air output from the outlet of the cathode of the first-stage fuel cell stack 3 is mixed with the cold air bypassing in the other path in the second mixer 16 and then enters the cathode of the second-stage fuel cell stack 7. The hot air output from the outlet of the cathode of the second-stage fuel cell stack 7 directly enters the burner 13 to provide oxygen for the combustion reaction.

[0131] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, rather than limitations on the implementation manners of the present invention. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the claims of the present invention.

Claims

1. A temperature control method for a fuel cell system, the fuel cell system comprising at least one fuel cell stack, characterized in that: The temperature control method of the fuel cell system includes a precise adjustment method, wherein the precise adjustment method includes feedforward adjustment, and the feedforward adjustment includes: Set the required temperature of the cathode outlet of the battery stack; Obtain the actual temperature of the cathode outlet of the battery stack; When the required temperature at the cathode outlet of the stack is not equal to the actual temperature at the cathode outlet of the stack, obtaining performance parameters of the stack, the performance parameters of the stack including the power generation per unit time of the stack, the heat dissipation per unit time of the stack, and the anode enthalpy difference of the stack, the anode enthalpy difference of the stack being the enthalpy difference between the anode inlet of the stack and the anode outlet of the stack; Determine a cathode enthalpy difference of the stack based on the power generation per unit time of the stack, the heat dissipation per unit time of the stack, and the anode enthalpy difference of the stack, the cathode enthalpy difference of the stack being the enthalpy difference between a cathode inlet of the stack and a cathode outlet of the stack; Determining a required enthalpy value at a cathode outlet of the stack based on a required temperature at a cathode outlet of the stack; Determining a required enthalpy value at a cathode inlet of the stack based on a cathode enthalpy difference of the stack and a required enthalpy value at a cathode outlet of the stack; Determine a feedforward temperature at a cathode inlet of the stack based on a required enthalpy value of a cathode inlet of the stack, and use the feedforward temperature at the cathode inlet of the stack as an execution temperature; The temperature of the air reaches the execution temperature and is input to the cathode inlet of the fuel cell stack.

2. The temperature control method of the fuel cell system according to claim 1, characterized in that: Methods for obtaining the power generation per unit time of the battery stack include: Obtain the output voltage and current of the battery stack; The amount of power generated by the stack per unit time is equal to the product of the stack's output voltage and the stack's output current.

3. The temperature control method of the fuel cell system according to claim 1, characterized in that: Methods for calculating the heat dissipation of the battery stack per unit time include: Obtain the mass of the battery stack and the temperature change of the battery stack per unit time; The amount of heat dissipated by the fuel cell stack per unit time is determined based on the mass of the fuel cell stack and the temperature change of the fuel cell stack per unit time.

4. The temperature control method of the fuel cell system according to claim 1, characterized in that: Methods for obtaining the anode enthalpy difference of the stack include: Determine whether the anode inlet of the stack is connected to a reformer; If yes, then obtain the actual temperature of the outlet of the reformer, the oxygen-carbon ratio of the gas entering the anode of the stack, the actual temperature of the anode inlet of the stack, and the actual temperature of the anode outlet of the stack; The anode enthalpy difference of the stack is determined based on the actual temperature at the outlet of the reformer, the oxygen-carbon ratio, the actual temperature at the anode inlet of the stack, and the actual temperature at the anode outlet of the stack.

5. The temperature control method of the fuel cell system according to claim 4, characterized in that: If the anode inlet of the stack is not connected to a reformer, the composition of the fuel gas entering the anode of the stack, the flow rate per unit time of the fuel gas entering the anode of the stack, the actual temperature of the anode inlet of the stack, and the actual temperature of the anode outlet of the stack are obtained; The anode enthalpy difference of the stack is determined based on the composition of the fuel gas at the stack anode, the flow rate per unit time of the fuel gas entering the stack anode, the actual temperature at the stack anode inlet and the actual temperature at the stack anode outlet.

6. The temperature control method of the fuel cell system according to claim 1, characterized in that: The precise adjustment method further includes feedback adjustment after the feedforward adjustment, and the feedback adjustment includes: Obtain the actual temperature of the cathode outlet of the battery stack; Compare the actual temperature at the cathode outlet of the stack with the required temperature at the cathode outlet of the stack; If the actual temperature at the cathode outlet of the stack is greater than the required temperature at the cathode outlet of the stack; Then the execution temperature is reduced by a set value on the existing basis; The temperature of the air reaches the execution temperature and is input to the cathode inlet of the fuel cell stack.

7. The temperature control method of the fuel cell system according to claim 6, characterized in that: If the actual temperature at the cathode outlet of the stack is lower than the required temperature at the cathode outlet of the stack; Then the execution temperature is increased by a set value on the existing basis; The temperature of the air reaches the execution temperature and is input to the cathode inlet of the fuel cell stack.

8. The temperature control method of the fuel cell system according to claim 1, characterized in that: The temperature control method of the fuel cell system includes a range adjustment method, and the range adjustment method includes: Obtaining the actual temperature of the fuel cell stack outlet, where the actual temperature of the fuel cell stack outlet is the actual temperature of the fuel cell stack anode outlet or the actual temperature of the fuel cell stack cathode outlet; Determine whether the actual temperature at the stack outlet exceeds the safety threshold; If so, the power generation power of the fuel cell stack is reduced by a preset power value, and the step of obtaining the actual temperature at the fuel cell stack outlet is repeated.

9. A fuel cell system, characterized in that: A temperature control method for a fuel cell system according to any one of claims 1 to 8, wherein the fuel cell system comprises: Two battery stacks, the two battery stacks are respectively a primary battery stack and a secondary battery stack; The reformer is connected to the anode inlet of the first-stage fuel cell stack; The gas-supplementing mixer is arranged between the primary stack and the secondary stack, and is used to mix the tail gas output from the anode outlet of the primary stack with the supplementary fresh fuel gas and then transport the mixed gas to the anode inlet of the secondary stack; A first mixer, used for mixing the heated hot air and the cold air and delivering the mixed air to the cathode inlet of the first-stage fuel cell stack; The second mixer is used to mix the exhaust gas output from the anode outlet of the first-stage fuel cell stack with the cold air and then transport them to the cathode inlet of the second-stage fuel cell stack.

10. The fuel cell system according to claim 9, characterized in that: The fuel cell system further comprises: A burner, wherein the burner is connected to the anode outlet of the secondary stack and the cathode outlet of the secondary stack; The air preheater is used to supply the heat generated by the combustion of the burner, and the air preheater is used to heat the cold air and then transport it to the first mixer.

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