A method and apparatus for cold starting an electrical stack

Abstract

This invention discloses a cold start method and apparatus for fuel cell stacks. The method includes acquiring the real-time operating temperature of the fuel cell stack and the corresponding core assembly model; determining the heat exchange power, solid-state heat transfer flux, and gas enthalpy corresponding to each control unit within the core assembly model based on the required temperature difference and the real-time operating temperature; responding to an electrothermal mode start command, calculating the sum of each heat exchange power and solid-state heat transfer flux as the electrothermal power of the heat box, and adjusting the inlet air flow for heating; responding to a gas-thermal mode start command, adjusting the inlet air temperature of the heat box according to the gas enthalpy, and adjusting the inlet air flow for heating. By simulating cold start using the core assembly model and responding to different mode start commands, the heat box is driven to heat using the sum of heat exchange efficiency and solid-state heat transfer flux or the gas enthalpy, thereby achieving rapid cold start of the fuel cell stack. This method effectively shortens the fuel cell stack heating time while ensuring flexible selection of heating methods at each stage.

Description

Technical Field

[0001] This invention relates to the field of fuel cell stack cold start technology, and more particularly to a cold start method and apparatus for fuel cell stacks. Background Technology

[0002] In renewable energy grids, to facilitate the grid's absorption of renewable energy, hydrogen produced by electricity needs to serve as a flexible resource, providing auxiliary services such as peak shaving and frequency regulation. In this context, hydrogen production systems need to be able to operate reliably and efficiently over a wide range, and to rapidly adjust their load levels to respond to and track regulation commands from the grid.

[0003] The cold start process of a solid oxide fuel cell (SOFC) stack requires a wide temperature range from room temperature to 600℃-900℃. The temperature change process is similar to the variable load process, and the temperature uniformity in this process must be controlled to avoid uneven heating that could cause thermal stress to exceed safety constraints.

[0004] Existing technologies typically employ a conservative and slow heating method to ensure temperature uniformity during cold starts, with this heating rate being... The cold start process can take several hours, resulting in low startup efficiency. Summary of the Invention

[0005] This invention provides a cold start method and apparatus for fuel cell stacks, solving the problem of the conservative and slow heating method commonly used in the prior art to ensure temperature uniformity during the cold start process. This heating rate is... The cold start process can take several hours, resulting in low startup efficiency.

[0006] This invention provides a cold start method for an electric fuel cell stack, wherein the stack is housed in a thermal enclosure, the method comprising:

[0007] Obtain the real-time operating temperature of the fuel cell stack and the corresponding core assembly model;

[0008] Based on the required temperature difference and the real-time operating temperature, determine the heat exchange power, solid heat transfer flux and gas enthalpy value corresponding to each control unit in the core module model;

[0009] If an electric heating mode start command is received, the sum of the heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box, and the air intake flow rate is adjusted until the fuel cell stack reaches the start-up temperature.

[0010] If a gas-heat mode start command is received, the inlet temperature of the heat box is adjusted according to the gas enthalpy value, and the inlet flow rate is adjusted until the fuel cell stack reaches the start-up temperature.

[0011] Optionally, the method further includes:

[0012] Obtain the structural information of the fuel cell stack and construct a core assembly model;

[0013] Establish a spatial coordinate axis with any vertex within the core assembly model as the origin;

[0014] The core model is discretized according to a preset number of coordinate axes in the spatial coordinate system to obtain multiple control units.

[0015] Optionally, determining the heat exchange power, solid heat transfer flux, and gas enthalpy corresponding to each control unit within the core module model based on the required temperature difference and the real-time operating temperature includes:

[0016] Obtain the solid heat exchange formula and gas heat exchange formula corresponding to the core assembly model;

[0017] Using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core model are calculated respectively.

[0018] Using the required temperature difference as the target and the real-time operating temperature as the input, the gas enthalpy value corresponding to each control unit in the core module model is calculated by combining the gas heat exchange formula.

[0019] Optionally, the step of calculating the sum of the heat exchange power and the solid heat transfer flux as the electric heating power of the heat box, and adjusting the air intake flow rate until the fuel cell stack reaches the start-up temperature, includes:

[0020] The sum of the heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box;

[0021] Set the air-side air intake flow rate to zero, set the hydrogen-side air intake flow rate to a first set value and adjust the gas composition to generate a mixed gas that is input into the fuel cell stack.

[0022] The heating box is driven to heat the fuel cell stack according to the electric heating power until the fuel cell stack reaches the start-up temperature.

[0023] Optionally, adjusting the inlet temperature of the heat box and the inlet flow rate according to the gas enthalpy value until the fuel cell stack reaches the start-up temperature includes:

[0024] The maximum value among the gas enthalpy values ​​is selected as the inlet temperature of the heat box;

[0025] Set the electric heating power of the heating box to zero;

[0026] Set the air-side intake flow rate to the second set value and the hydrogen-side intake flow rate to the third set value to generate a mixed gas.

[0027] A mixed gas is introduced into the fuel cell stack in a dual-channel co-current heating manner until the fuel cell stack reaches the start-up temperature.

[0028] The present invention also provides a cold start device for a fuel cell stack, the fuel cell stack being housed in a hot box, the device comprising:

[0029] The data and model acquisition module is used to acquire the real-time operating temperature of the fuel cell stack and the corresponding core assembly model.

[0030] The heating data solving module is used to determine the heat exchange power, solid heat transfer flux and gas enthalpy value of each control unit in the core group model according to the required temperature difference and the real-time operating temperature.

[0031] An electric heating cold start module is used to calculate the sum of the heat exchange power and the solid heat transfer flux as the electric heating power of the heat box if an electric heating mode start command is received, and adjust the air intake flow until the stack reaches the start temperature.

[0032] The gas-heated cold start module is used to adjust the inlet temperature of the heat box and the inlet flow rate according to the gas enthalpy value if a gas-heated mode start command is received, until the fuel cell stack reaches the start temperature.

[0033] Optionally, the device further includes:

[0034] The model creation module is used to obtain the structural information of the fuel cell stack and construct the core assembly model;

[0035] The coordinate axis creation module is used to establish a spatial coordinate axis with any vertex within the core assembly model as the origin.

[0036] The model discretization module is used to discretize the core model according to multiple coordinate axis directions of the spatial coordinate axis according to a preset number, so as to obtain multiple control units.

[0037] Optionally, the heating data solving module is specifically used for:

[0038] Obtain the solid heat exchange formula and gas heat exchange formula corresponding to the core assembly model;

[0039] Using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core model are calculated respectively.

[0040] Using the required temperature difference as the target and the real-time operating temperature as the input, the gas enthalpy value corresponding to each control unit in the core module model is calculated by combining the gas heat exchange formula.

[0041] Optionally, the electrothermal cold start module is specifically used for:

[0042] The sum of the heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box;

[0043] Set the air-side air intake flow rate to zero, set the hydrogen-side air intake flow rate to a first set value and adjust the gas composition to generate a mixed gas that is input into the fuel cell stack.

[0044] The heating box is driven to heat the fuel cell stack according to the electric heating power until the fuel cell stack reaches the start-up temperature.

[0045] Optionally, the gas-heated cold start module is specifically used for:

[0046] The maximum value among the gas enthalpy values ​​is selected as the inlet temperature of the heat box;

[0047] Set the electric heating power of the heating box to zero;

[0048] Set the air-side intake flow rate to the second set value and the hydrogen-side intake flow rate to the third set value to generate a mixed gas.

[0049] A mixed gas is introduced into the fuel cell stack in a dual-channel co-current heating manner until the fuel cell stack reaches the start-up temperature.

[0050] As can be seen from the above technical solutions, the present invention has the following advantages:

[0051] This invention obtains the real-time operating temperature of the fuel cell stack and the corresponding core assembly model. Based on the required temperature difference and the real-time operating temperature, it determines the heat exchange power, solid-state heat transfer flux, and gas enthalpy corresponding to each control unit within the core assembly model. If an electrothermal mode start-up command is received, the sum of each heat exchange power and solid-state heat transfer flux is calculated as the electrothermal power of the heat box, and the air intake flow rate is adjusted until the fuel cell stack reaches the start-up temperature. If a gas-thermal mode start-up command is received, the air intake temperature of the heat box is adjusted according to the gas enthalpy, and the air intake flow rate is adjusted until the fuel cell stack reaches the start-up temperature. By simulating a cold start using the core assembly model, the heat exchange efficiency of each control unit is calculated. Furthermore, in response to different mode start-up commands, the heat box is driven to heat up using the sum of the heat exchange efficiency and solid-state heat transfer flux or the gas enthalpy until the fuel cell stack reaches the start-up temperature, thereby achieving rapid cold start of the fuel cell stack. This ensures flexible selection of heating methods at each stage while effectively shortening the heating time of the fuel cell stack. Attached Figure Description

[0052] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0053] Figure 1 A flowchart illustrating the steps of a cold start method for an electric fuel cell stack, provided in an embodiment of the present invention;

[0054] Figure 2 This is a schematic diagram of a heat box structure provided in an embodiment of the present invention;

[0055] Figure 3 This is a schematic diagram of a core assembly model provided in an embodiment of the present invention;

[0056] Figure 4 This is a schematic diagram of four different gas heating methods for a SOC fuel cell stack provided in an embodiment of the present invention;

[0057] Figure 5 This is a structural block diagram of a cold start device for fuel cell stacks provided in an embodiment of the present invention. Detailed Implementation

[0058] SOFC stacks have relatively low power output per stack. To achieve capacity scaling, several stacks need to be integrated into an insulated heat exchanger to form modules with a power output of tens of kilowatts. These modules are then combined into systems ranging from hundreds of kilowatts to megawatts. This structure allows high-power, high-temperature electrohydrogen production systems to achieve flexible and efficient regulation over a wide load range through start-stop modules. However, the cold start process typically involves a large temperature change from room temperature to operating temperature, resulting in low start-up efficiency.

[0059] This invention provides a cold start method and apparatus for fuel cell stacks, addressing the problem that existing technologies typically employ conservative and slow heating methods to ensure temperature uniformity during cold start. This heating rate is... The cold start process can take several hours, resulting in low startup efficiency.

[0060] To make the objectives, features, and advantages of this invention more apparent and understandable, the technical solutions of the embodiments of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the embodiments described below are only some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0061] Please see Figure 1 , Figure 1 This is a flowchart illustrating the steps of a cold start method for an electric fuel cell stack, as provided in an embodiment of the present invention.

[0062] This invention provides a cold start method for an electric fuel cell stack, wherein the stack is housed in a hot box, and the method includes:

[0063] Step 101: Obtain the real-time operating temperature of the fuel cell stack and the corresponding core assembly model;

[0064] The fuel cell stack refers to the fuel cell stack body in a solid oxide fuel cell stack. The heat box is used to provide the high-temperature environment required for the fuel cell stack to operate and is used to house the fuel cell stack and the preheating coil for the intake air.

[0065] In this embodiment, the real-time operating temperature of the fuel cell stack is obtained through a temperature sensor on its periphery, providing a data basis for subsequent temperature adjustments.

[0066] Meanwhile, for fuel cell stacks with different structures, parameters, and sizes, corresponding core assembly models can be established according to their different stacks to analyze their heat exchange processes, simulate the temperature changes of the fuel cell stack during cold start, and improve its cold start efficiency while ensuring safety.

[0067] It should be noted that the thermal box structure corresponding to fuel cell stack 1 can be as follows: Figure 2 As shown, the heat-insulating box is mainly composed of three layers of materials. The innermost layer, ceramic fiber board 3, has high mechanical strength and can support the electric stack. Electric heating wires 2 are installed on its inner wall. The middle main heat-insulating material is aerogel felt 4, whose thermal conductivity at room temperature is less than 0.04 W / (m·K). The outermost layer is a stainless steel sheet 5, which plays a role in fixing.

[0068] In one example of this application, the method further includes:

[0069] Obtain structural information of the fuel cell stack and construct a core assembly model;

[0070] Establish a spatial coordinate axis with any vertex within the core assembly model as the origin;

[0071] The core model is discretized according to a preset number of coordinate axes in the spatial coordinate system to obtain multiple control units.

[0072] In this embodiment, the dimensions of the fuel cell stack can be measured, and the material of the stack can be detected to construct a core assembly model. The structural information refers to the dimensions and inherent parameters of the fuel cell stack, such as the stack material and various physical parameters of the stack in its inactive state. This core assembly model can be constructed as follows: Figure 3 As shown.

[0073] After completing the core assembly model, a spatial coordinate axis is established with any vertex within the core assembly model as the origin. The core assembly model is then discretized into Nx, Ny, and Nz control units in the x, y, and z axes, respectively. Along the gas flow direction, i.e., the x-axis, the fuel cell stack is discretized into 6 control units to verify the temperature distribution of the hot gas flow; in the y and z axes, the fuel cell stack is discretized into 3 control units each.

[0074] Step 102: Based on the required temperature difference and real-time operating temperature, determine the heat exchange power, solid heat transfer flux and gas enthalpy value corresponding to each control unit in the core module model.

[0075] In one example of this application, step 102 may include the following sub-steps:

[0076] Obtain the solid-state heat exchange formula and the gas-gas heat exchange formula corresponding to the core assembly model;

[0077] Using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core model are calculated.

[0078] Using the required temperature difference as the target and the real-time operating temperature as the input, the gas enthalpy value corresponding to each control unit in the core module model is calculated by combining the gas heat exchange formula.

[0079] The solid heat exchange formula is as follows:

[0080]

[0081] The gas heat exchange formula is:

[0082]

[0083] in, , These represent the heat capacities of solids and gases, respectively. , These represent the densities of solids and gases, respectively. , These represent the volumes of solids and gases, respectively. , Let represent the solid and gas temperatures respectively; R represents the ideal gas constant (8.314 J / (mol·K)); the gas and solid temperatures of the control unit numbered (i,j,k) are respectively represented by the lumped temperature variable. and Let Pex represent the heat exchange power between a control volume and adjacent control units. Applying the law of conservation of energy to the solid portion of each control unit yields the solid heat exchange formula. The subscripts "xb" and "xf" represent the negative (backward) and positive (forward) directions of the x-axis, respectively, and the meanings of "yb," "yf," "zb," and "zf" follow the same pattern. con This represents the heat flux transferred to the solid, i.e., the convective heat transfer between the gas and solid within the same control unit. This model considers heat conduction between adjacent control units, convective heat transfer between the solid and gas within the same control unit, and convective and radiative heat transfer between the fuel cell stack and the heat box. The gas heat exchange formula is obtained by applying the law of conservation of energy to the gas portion of each control unit. Here, ∆H represents the difference between the enthalpy of the gas flowing into and out of the control unit, and (i,j,k) represents the multidimensional count variables of the control unit.

[0084] In this embodiment, using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core module model are calculated. This means the actual temperature is fed back in real time, and the heat power P is updated in real time based on the required temperature difference T. Similarly, for the gas heating section, using the required temperature difference as the target and the real-time operating temperature as the input, and combining the gas heat exchange formula, the gas enthalpy value corresponding to each control unit in the core module model is calculated.

[0085] During cold start, the hot box is first heated and stabilized at its initial temperature, while the fuel cell stack has not yet reached its operating temperature and the electrochemical reaction has not fully commenced. Therefore, this fuel cell stack model primarily considers the temperature and flow fields. Depending on the heating method, cold start has two modes: electrothermal and gas-thermal. To control the maximum temperature difference within the fuel cell stack, the maximum and minimum temperatures within the stack need to be fed back to the controller as system outputs. Based on the heat transfer mechanisms in electrothermal and gas-thermal modes, the maximum temperature in the electrothermal mode is at the apex of the fuel cell stack's outer surface, and the minimum temperature is at the center of the stack; in the gas-thermal mode, the maximum temperature is at the center of the stack's inlet surface, and the minimum temperature is at the apex of the stack's outlet surface. This required temperature difference can be calculated using historical values ​​of the maximum and minimum temperatures.

[0086] In this embodiment, the cold start of the fuel cell stack can be divided into two different modes: electrothermal mode and gas-thermal mode. By responding to external start commands, the heating power or intake temperature of the external heat box or the heat box intake is adjusted, thereby performing phased and controllable heating of the fuel cell stack and realizing the cold start of the fuel cell stack.

[0087] Step 103: If an electric heating mode start command is received, calculate the sum of each heat exchange power and solid heat transfer flux as the electric heating power of the heat box, and adjust the air intake flow until the fuel cell stack reaches the start temperature.

[0088] In one example of this application, step 103 may include the following sub-steps:

[0089] The sum of each heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box;

[0090] Set the air-side intake flow rate to zero, set the hydrogen-side intake flow rate to the first set value and adjust the gas composition to generate a mixed gas that is input into the fuel cell stack.

[0091] The drive heat box heats the fuel cell stack according to the electric heating power until the fuel cell stack reaches the start-up temperature.

[0092] In this embodiment, if an electrothermal mode start command is received, it indicates that the fuel cell stack needs to be heated in stages using a solid medium via a heat box. The sum of each heat exchange power and the solid heat transfer flux can be calculated as the electrothermal power P of the heat box. h Since the temperature of each control unit in the aforementioned fuel cell stack changes continuously due to heat exchange with the solid medium, the electric heating power also changes in real time to meet the required temperature difference and improve cold start efficiency, thus affecting the temperature distribution in the fuel cell stack by controlling the boundary conditions.

[0093] Meanwhile, during the cold start phase, to reduce energy consumption and quickly bring the fuel cell stack to the required temperature, the air-side inlet flow rate is set to 0, and the hydrogen-side flow rate is set to 1.344 slm. As a protective gas, its composition can be adjusted to 4% H2 and 96% H2O to create a reducing atmosphere and prevent oxidation of the hydrogen electrode, generating a mixed gas that is then introduced into the fuel cell stack. The hot box heats the fuel cell stack according to continuously varying electrical heating power until the stack reaches the start-up temperature.

[0094] Step 104: If a gas-heat mode start command is received, adjust the inlet temperature of the heat box according to the gas enthalpy value and adjust the inlet flow rate until the fuel cell stack reaches the start temperature.

[0095] In one example of this application, step 104 may include the following sub-steps:

[0096] The maximum value of the gas enthalpy is selected as the inlet temperature of the hot box;

[0097] Set the electric heating power of the heating box to zero;

[0098] Set the air-side intake flow rate to the second set value and the hydrogen-side intake flow rate to the third set value to generate a mixed gas.

[0099] A mixed gas is introduced into the fuel cell stack in a dual-channel co-current heating manner until the fuel cell stack reaches the start-up temperature.

[0100] In this embodiment, if a gas-heat mode start command is received, it indicates that the fuel cell stack needs to be heated in stages using a gas medium via a heat box. At this time, the electric heating power of the heat box is commanded, with the inlet air temperature as a controllable variable. During the start-up phase, in order to avoid a high local temperature gradient at the fuel cell stack inlet, which would be detrimental to fuel cell stack safety, a higher air inlet flow rate is selected to balance the fuel cell stack temperature. The air-side air inlet flow rate is set to a second set value, and the hydrogen-side air inlet flow rate is set to a third set value, that is, the air-side air inlet flow rate is set to 200 slm and the hydrogen-side flow rate is set to 1.344 slm. The gas generated by this air and hydrogen flow rate is input into the fuel cell stack to heat the fuel cell stack until the fuel cell stack reaches the start-up temperature.

[0101] It should be noted that the high-temperature gas heating methods for high-temperature solid oxide fuel cells are mainly divided into two categories: dual-channel heating and single-channel heating. Dual-channel heating refers to simultaneously introducing heating gas into both channels to heat the fuel cell stack. Based on the direction of the heating gas flow, it can be further divided into three types: co-current, counter-current, and cross-current heating. Different heating methods have a significant impact on the cell temperature rise. Figure 4The diagram illustrates four different gas heating methods for a State of Charge (SOC) battery stack. As shown, in counter-current heating, the heating gas flows in opposite directions within the electrode channels; in co-current heating, the heating gas flows in the same direction within the anode and cathode channels; in single-channel anode heating, the heating gas flows only within the anode channel, while the gas in the cathode channel remains stationary; and in single-channel cathode heating, the heating gas flows only within the cathode channel, while the gas in the anode channel remains stationary. The lowest temperature of the SOC battery stack is a crucial indicator of the end of the battery heating process. Under the same heating parameters, the dual-channel heating method takes less time than the single-channel heating method because the heat flux in the dual-channel method is twice that in the single-channel method. Within the single-channel heating method, the heating times for the anode and cathode are essentially the same due to the similar solid structures and physical properties of the electrodes. In the dual-channel heating method, the co-current heating method heats the battery stack in less time than the counter-current heating method, enabling faster heating to the target temperature. Therefore, this embodiment employs a dual-channel co-current heating method, adjusting the temperature gradient and hot gas flow rate based on the inlet effect. Specifically, during the heating start-up process, the maximum temperature gradient of the battery exists at the inlet of the heating gas channel. As the average temperature inside the battery increases, the temperature gradient can be reduced by decreasing the inlet temperature of the heating gas. Increasing the inlet heating rate increases the temperature difference between the battery and the heating gas, thereby enhancing the heat transfer intensity between the heating gas and the battery, leading to an increase in the maximum temperature gradient inside the battery and a decrease in the preheating time. Increasing the inlet velocity enhances heat transfer between the heating gas and the battery, reducing the maximum temperature gradient inside the battery, and also increases the heat flow rate of the heating gas entering the battery channel per unit time, accelerating the battery heating rate. Increasing the channel back pressure increases the density of the heating gas within the channel, thereby increasing the heat transfer intensity between the gas and the battery and the heat flow rate of the heating gas per unit time, resulting in a decrease in the maximum temperature gradient inside the battery and the preheating time.

[0102] In this embodiment, under the same heating parameters, the heat flow rate entering the battery channel per unit time in the dual-channel heating method is approximately twice that of the single-channel method, thus requiring a shorter preheating time. During heating, due to the superior thermal properties of the anode compared to the cathode and the anode-supported stack model in this paper, the battery temperature gradient is minimized under the anode-single-channel heating method. In the dual-channel heating method, when the heating gas inlet heating rate and velocity are low, the preheating time is shorter and the temperature gradient is smaller using the co-current heating method; when the heating gas inlet heating rate and velocity are high, the counter-current heating time is shorter, but the internal temperature gradient is larger. In the single-channel heating method, the heating time required for cathode heating and anode heating is essentially the same; however, the maximum internal temperature gradient of the battery using the anode heating method is much smaller than that using the cathode heating method. By controlling the heating rate and the holding temperature at the end of the heating gas phase in stages, the uniformity of the internal temperature distribution of the stack can be balanced, thereby effectively shortening the battery heating time.

[0103] The excellent insulation performance of the heat box results in a relatively uniform temperature distribution inside. Since heat transfer is driven by temperature difference, increasing the temperature difference between the heating gas and the battery stack, or raising the inlet temperature of the heating gas, is a simple and effective way to improve heat transfer between them. However, the heating gas has a low heat capacity, and its temperature drops rapidly along the flow path. This means that only the part of the battery near the inlet begins to heat up, while the inner parts only absorb heat after the temperature of the outer parts rises. This explains why the rate of temperature rise of the battery's lowest internal temperature increases over time. Therefore, heating the battery stack requires not only creating a temperature difference or gradient between the heating gas and the battery, but also a temperature difference between the battery inlet / outlet and the middle, or a temperature gradient along the heating gas flow direction (X direction).

[0104] Based on the battery heating characteristics, this paper proposes an optimized heating scheme for the inlet heating rate of the heating gas: At the initial stage of heating, a full-load heating rate is selected to rapidly increase the temperature difference between the heating gas and the battery components, accelerating the formation and development of the temperature gradient along the flow channel until the maximum temperature gradient inside the battery reaches within a safe threshold. Then, temperature difference PID control is activated to adjust the inlet heating rate of the heating gas to stabilize the temperature difference at the set value, thereby keeping the stack at a safe temperature gradient for efficient heating during the heating process until the stack exceeds the operating temperature, at which point the inlet heating rate becomes zero. At this point, the stack temperature should be higher than the battery startup temperature to enable the stack to start up rapidly. Subsequently, as the electrochemical reaction of the stack proceeds, it will release reaction heat, reducing the heating temperature and stabilizing the stack at the operating temperature.

[0105] In this embodiment, the real-time operating temperature of the fuel cell stack and the corresponding core model are obtained. Based on the required temperature difference and the real-time operating temperature, the heat exchange power, solid heat transfer flux, and gas enthalpy corresponding to each control unit within the core model are determined. If an electrothermal mode start command is received, the sum of each heat exchange power and solid heat transfer flux is calculated as the electrothermal power of the heat box, and the air intake flow rate is adjusted until the fuel cell stack reaches the start temperature. If a gas-thermal mode start command is received, the air intake temperature of the heat box is adjusted according to the gas enthalpy, and the air intake flow rate is adjusted until the fuel cell stack reaches the start temperature. By simulating a cold start using the core model, the heat exchange efficiency of each control unit is calculated. Further, in response to different mode start commands, the heat box is driven to heat up using the sum of the heat exchange efficiency and solid heat transfer flux or the gas enthalpy until the fuel cell stack reaches the start temperature, thereby achieving rapid cold start of the fuel cell stack. This ensures flexible selection of heating methods at each stage while effectively shortening the heating time of the fuel cell stack.

[0106] Light Reference Figure 5 , Figure 5 A structural block diagram of a cold start device for an electric stack according to an embodiment of this application is shown.

[0107] The present invention also provides a cold start device for a fuel cell stack, wherein the fuel cell stack is housed in a hot box, and the device includes:

[0108] The data and model acquisition module 501 is used to acquire the real-time operating temperature of the fuel cell stack and the corresponding core assembly model.

[0109] The heating data solving module 502 is used to determine the heat exchange power, solid heat transfer flux and gas enthalpy value of each control unit in the core group model according to the required temperature difference and real-time operating temperature.

[0110] The electric heating cold start module 503 is used to calculate the sum of each heat exchange power and solid heat transfer heat flux as the electric heating power of the heat box if an electric heating mode start command is received, and adjust the air intake flow until the fuel cell stack reaches the start temperature.

[0111] The gas-heated cold start module 504 is used to adjust the inlet temperature of the heat box according to the gas enthalpy value and adjust the inlet flow rate until the fuel cell stack reaches the start-up temperature if a gas-heated mode start command is received.

[0112] Optionally, the device further includes:

[0113] The model creation module is used to obtain the structural information of the fuel cell stack and build the core assembly model;

[0114] The coordinate axis creation module is used to establish spatial coordinate axes with any vertex within the core model as the origin;

[0115] The model discretization module is used to discretize the core model according to multiple coordinate axes of the spatial coordinate system, according to a preset number of axes, to obtain multiple control units.

[0116] Optionally, the heating data solving module 502 is specifically used for:

[0117] Obtain the solid-state heat exchange formula and the gas-gas heat exchange formula corresponding to the core assembly model;

[0118] Using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core model are calculated.

[0119] Using the required temperature difference as the target and the real-time operating temperature as the input, the gas enthalpy value corresponding to each control unit in the core module model is calculated by combining the gas heat exchange formula.

[0120] Optionally, the electrically heated cold start module 503 is specifically used for:

[0121] The sum of each heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box;

[0122] Set the air-side intake flow rate to zero, set the hydrogen-side intake flow rate to the first set value and adjust the gas composition to generate a mixed gas that is input into the fuel cell stack.

[0123] The drive heat box heats the fuel cell stack according to the electric heating power until the fuel cell stack reaches the start-up temperature.

[0124] Optionally, the gas-heated cold start module 504 is specifically used for:

[0125] The maximum value of the gas enthalpy is selected as the inlet temperature of the hot box;

[0126] Set the electric heating power of the heating box to zero;

[0127] Set the air-side intake flow rate to the second set value and the hydrogen-side intake flow rate to the third set value to generate a mixed gas.

[0128] A mixed gas is introduced into the fuel cell stack in a dual-channel co-current heating manner until the fuel cell stack reaches the start-up temperature.

[0129] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working process of the above-described device and module can be referred to the corresponding process in the foregoing method embodiments, and will not be repeated here.

[0130] In the several embodiments provided in this application, it should be understood that the disclosed apparatus and methods can be implemented in other ways. For example, the apparatus embodiments described above are merely illustrative; for instance, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. For example, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Furthermore, the coupling or direct coupling or communication connection shown or discussed may be through some interfaces; the indirect coupling or communication connection between apparatuses or modules may be electrical, mechanical, or other forms.

[0131] The above-described embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A cold start method for fuel cell stacks, characterized in that, The fuel cell stack is housed in a thermal box, and the method includes: Obtain the real-time operating temperature of the fuel cell stack and the corresponding core assembly model; Based on the required temperature difference and the real-time operating temperature, determine the heat exchange power, solid heat transfer flux and gas enthalpy value corresponding to each control unit in the core module model; If an electric heating mode start command is received, the sum of the heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box, and the air intake flow rate is adjusted until the fuel cell stack reaches the start-up temperature. If a gas-heat mode start command is received, the maximum value of the gas enthalpy is selected as the inlet temperature of the heat box, and the inlet flow rate is adjusted until the fuel cell stack reaches the start temperature. The calculation of the sum of the heat exchange power and the solid heat transfer flux as the electric heating power of the heat box, and the adjustment of the air intake flow rate until the fuel cell stack reaches the start-up temperature, includes: The sum of the heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box; The air-side intake flow rate is set to zero, the hydrogen-side intake flow rate is set to a first set value and the gas composition is adjusted to generate a mixed gas that is input into the fuel cell stack; the gas composition is 4% H2 and 96% H2O. The heating box is driven to heat the fuel cell stack according to the electric heating power until the fuel cell stack reaches the start-up temperature.

2. The method of claim 1, wherein, The method further includes: Obtain the structural information of the fuel cell stack and construct a core assembly model; Establish a spatial coordinate axis with any vertex within the core assembly model as the origin; The core model is discretized according to a preset number of coordinate axes in the spatial coordinate system to obtain multiple control units.

3. The method of claim 1, wherein, The step of determining the heat exchange power, solid heat transfer flux, and gas enthalpy of each control unit within the core module model based on the required temperature difference and the real-time operating temperature includes: Obtain the solid heat exchange formula and gas heat exchange formula corresponding to the core assembly model; Using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core model are calculated respectively. Using the required temperature difference as the target and the real-time operating temperature as the input, the gas enthalpy value corresponding to each control unit in the core module model is calculated by combining the gas heat exchange formula.

4. The method of claim 1, wherein, The step of selecting the maximum value among the gas enthalpy values ​​as the inlet temperature of the heat box and adjusting the inlet flow rate until the fuel cell stack reaches the start-up temperature includes: The maximum value among the gas enthalpy values ​​is selected as the inlet temperature of the heat box; Set the electric heating power of the heating box to zero; Set the air-side intake flow rate to the second set value and the hydrogen-side intake flow rate to the third set value to generate a mixed gas. A mixed gas is introduced into the fuel cell stack in a dual-channel co-current heating manner until the fuel cell stack reaches the start-up temperature.

5. A cold start device for an electrical stack, characterized in that The fuel cell stack is housed in a thermal box, and the device includes: The data and model acquisition module is used to acquire the real-time operating temperature of the fuel cell stack and the corresponding core assembly model. The heating data solving module is used to determine the heat exchange power, solid heat transfer flux and gas enthalpy value of each control unit in the core group model according to the required temperature difference and the real-time operating temperature. An electric heating cold start module is used to calculate the sum of the heat exchange power and the solid heat transfer flux as the electric heating power of the heat box if an electric heating mode start command is received, and adjust the air intake flow until the stack reaches the start temperature. The gas-heated cold start module is used to select the maximum value of the gas enthalpy as the inlet temperature of the heat box and adjust the inlet flow rate until the fuel cell stack reaches the start-up temperature if a gas-heated mode start command is received. The electrothermal cold start module is specifically used for: The sum of the heat exchange power and the solid heat transfer flux is calculated as the electric heating power of the heat box; The air-side intake flow rate is set to zero, the hydrogen-side intake flow rate is set to a first set value and the gas composition is adjusted to generate a mixed gas that is input into the fuel cell stack; the gas composition is 4% H2 and 96% H2O. The heating box is driven to heat the fuel cell stack according to the electric heating power until the fuel cell stack reaches the start-up temperature.

6. The apparatus of claim 5, wherein, The device further includes: The model creation module is used to obtain the structural information of the fuel cell stack and construct the core assembly model; The coordinate axis creation module is used to establish a spatial coordinate axis with any vertex within the core assembly model as the origin. The model discretization module is used to discretize the core model according to multiple coordinate axis directions of the spatial coordinate axis according to a preset number, so as to obtain multiple control units.

7. The apparatus of claim 5, wherein, The heating data solving module is specifically used for: Obtain the solid heat exchange formula and gas heat exchange formula corresponding to the core assembly model; Using the required temperature difference as the target and the real-time operating temperature as the input, and combining the solid heat exchange formula, the heat exchange power and solid heat transfer flux corresponding to each control unit in the core model are calculated respectively. Using the required temperature difference as the target and the real-time operating temperature as the input, the gas enthalpy value corresponding to each control unit in the core module model is calculated by combining the gas heat exchange formula.

8. The apparatus of claim 5, wherein, The gas-heated cold start module is specifically used for: The maximum value among the gas enthalpy values ​​is selected as the inlet temperature of the heat box; Set the electric heating power of the heating box to zero; Set the air-side intake flow rate to the second set value and the hydrogen-side intake flow rate to the third set value to generate a mixed gas. A mixed gas is introduced into the fuel cell stack in a dual-channel co-current heating manner until the fuel cell stack reaches the start-up temperature.

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