Fuel cell device and low-temperature starting method thereof

Abstract

The invention relates to a fuel cell device and a low-temperature starting method thereof. The fuel cell device comprises a fuel cell stack, an air supply system, a hydrogen supply system, a slow freezing agent supply system and a control system, wherein the air supply system is directly communicated with the fuel cell stack and is used for providing air for the fuel cell stack; the hydrogen supply system is directly communicated with the fuel cell stack and is used for providing hydrogen for the fuel cell stack; the air supply system and the hydrogen supply system are also communicated with the fuel cell stack through the slow freezing agent supply system so as to respectively provide air carrying slow freezing gas and hydrogen for the fuel cell stack; and the control system is electrically connected with the fuel cell stack, the air supply system, the hydrogen supply system and the slow-freezing agent supply system. A slow freezing agent supply system is arranged in the fuel cell device, and a gas supply strategy is optimized, so that the fuel stack can be smoothly started during restarting after low-temperature long-time shutdown.

Description

Technical Field

[0001] The present application relates to the field of fuel cell technology, and in particular to a fuel cell device and a low-temperature starting method thereof. Background Art

[0002] As a vehicle power scenario, fuel cells must be able to start and stop multiple times a day and restart after long periods of parking, which are essential basic functions. In the hot engine state or in an environment with a temperature above 0°C, the fuel cell stack can be quickly started again after multiple short starts and stops or long periods of shutdown. However, in an environment with a temperature close to or below 0°C, the factors affecting the start and stop of fuel cells become complicated. First, the water left in the gas transport duct after shutdown will freeze, hindering the passage of gas when restarted, causing a response start failure. Second, the heat generated by the reaction after startup is not enough to meet the heat required for the water generated by the reaction to resist freezing, resulting in an actual start failure.

[0003] In response to the failure of response startup, the traditional treatment method is generally to use a drainage and purge strategy after shutdown. The purpose of the purge is to remove the moisture in the gas transport channel through gas flow to prevent the moisture from freezing at low temperatures and blocking the channel, hindering the passage of gas when restarting, and causing response startup failure. In response to actual startup failure, the traditional treatment method is generally to form a complex startup procedure based on the thermal capacity and structural design of the battery stack material combined with the startup load rate. However, this requires a lot of design experience and repeated actual machine tests to complete, which brings great challenges to the emerging industry of fuel cells. In addition, for ultra-low temperatures of -30℃ to -40℃, the startup time is long and the probability of successful startup is low. Summary of the invention

[0004] In order to solve the above problems, the present application provides a fuel cell device and a low-temperature startup method thereof. A refrigerant supply system is provided in the fuel cell device to provide air and hydrogen carrying refrigerant gas to the fuel cell stack; in the initial stage of stack startup, the gas carrying refrigerant is used to supply gas to the fuel cell stack reaction, and the standard gas supply strategy is switched after the internal temperature of the stack reaches a sufficiently high level, thereby eliminating factors that affect the actual startup.

[0005] The first aspect of the present application provides a fuel cell device, comprising: a fuel cell stack, an air supply system, a hydrogen supply system, a retarder supply system and a control system; wherein the air supply system is directly connected to the fuel cell stack to provide air to the fuel cell stack;

[0006] The hydrogen supply system is directly connected to the fuel cell stack to provide hydrogen to the fuel cell stack;

[0007] The air supply system and the hydrogen supply system are also connected to the fuel cell stack via the retarder supply system, so as to respectively provide the fuel cell stack with air and hydrogen carrying retarder gas;

[0008] The control system is electrically connected to the fuel cell stack, the air supply system, the hydrogen supply system and the refrigerant supply system.

[0009] In some embodiments, the fuel cell device further includes a drain valve for draining waste gas / liquid generated after the fuel cell stack reaction.

[0010] In some embodiments, the air supply system includes an air compressor and an air intercooler; the air compressor, the air intercooler, the fuel cell stack and the exhaust valve are connected in sequence; at the same time, the air compressor and the air intercooler are also connected to the refrigerant supply system, the fuel cell stack and the exhaust valve in sequence.

[0011] In some embodiments, the hydrogen supply system includes a hydrogen conveyor and a nitrogen drainer; the hydrogen conveyor, the fuel cell stack, and the nitrogen drainer are sequentially connected to form a first loop. Meanwhile, the hydrogen conveyor, the retardant supply system, the fuel cell stack, and the nitrogen drainer are sequentially connected to form a second loop.

[0012] In some embodiments, the retardant supply system includes a temperature-controllable electric heater, a retardant introducer body, a cathode and cathode gas chamber partitions, and retardant. The temperature-controllable electric heater is used to heat the retardant introducer body; the retardant introducer body is divided into left and right chambers by the cathode and cathode gas chamber partitions; and the retardant is enclosed in the left and right chambers.

[0013] In some embodiments, the temperature-controllable electric heater controls the heating temperature to be below 60°C.

[0014] A second aspect of the present application provides a low temperature start-up method for a fuel cell device, comprising the following steps:

[0015] S1. After the fuel cell device is shut down, the standard gas supply strategy is used to drain and purge the inside of the fuel cell device. When the impedance measurement value (R1) of the fuel cell stack after purge gradually increases to reach the preset impedance R value, the gas supply is stopped and the device is parked;

[0016] S2, restart, measure the stack impedance (R2) before starting, when R2 is not higher than R1, adopt the standard gas supply strategy; when R2 is higher than R1, adopt the slow freezing gas supply strategy;

[0017] S3. When the fuel cell stack is successfully started and the temperature rises above 5°C, the reaction gas is switched to the standard reaction gas.

[0018] In some embodiments, step S1 is specifically as follows: after the fuel cell device is shut down, the first, third and fifth three-way valves are opened, the second, fourth and sixth three-way valves are closed, and air is introduced into the cathode of the battery stack through the air supply system; hydrogen is introduced into the anode of the battery stack through the hydrogen supply system until R1=R, and then the gas is stopped and the stack is parked.

[0019] In some embodiments, in step S2, when R2 is higher than R1, the second, third and sixth three-way valves are opened, the first, fourth and fifth three-way valves are closed, and air carrying defrosting gas is introduced into the cathode of the battery stack through the air supply system and the defrosting agent supply system; hydrogen carrying defrosting gas is introduced into the anode of the battery stack through the hydrogen supply system and the defrosting agent supply system.

[0020] In some embodiments, the following step is further included between step S2 and step S3: when the outlet temperature of the fuel cell stack coolant reaches 0° C., the refrigerant supply system is turned off.

[0021] In some embodiments, step S2 and / or S3 further includes the following steps: when the concentration of nitrogen infiltrated into the hydrogen rises to a set value or the precipitated water reaches a limited height of the liquid level, the third three-way valve is closed, the fourth three-way valve is opened, and the mixed gas and liquid are drained from the drain valve through the nitrogen drainer.

[0022] According to the operating mechanism and characteristics of the fuel cell stack, this application sets a refrigerant supply system in the fuel cell device to optimize the gas supply strategy, so that when the fuel cell stack is shut down for a long time in a low temperature environment (≤0°C), the stack adopts the refrigerant gas supply strategy when restarting until the fuel stack starts smoothly and the coolant temperature rises to above 5°C, and then replaces the standard gas supply strategy to make the stack operate normally. The overall gas supply strategy provided by the device increases the low-temperature startup speed of the stack by more than 80%, and the startup success rate reaches 100%. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 FIG. 1 is a schematic diagram of a fuel cell device in an embodiment of the present application.

[0024] Figure 2 Schematic diagram of a retarder supply system in one embodiment of the present application.

[0025] Figure 3 Schematic diagram of a low-temperature startup method for a fuel cell device in one embodiment of the present application.

[0026] Notes on the attached drawings:

[0027] 1. Fuel cell stack; 2. Air compressor; 3. Air intercooler; 4. Hydrogen transporter; 5. Nitrogen drainer; 6. Defrosting agent supply system; 7. Drain valve; 8. Temperature-controllable electric heater; 9. Defrosting agent introducer body; 10. Anode and cathode gas chamber partitions; 11. Defrosting agent; 12. Air inlet pipe; 13. Air outlet pipe; 14. Hydrogen inlet pipe; 15. Hydrogen outlet pipe; 16. Control system; 17. First three-way valve; 18. Second three-way valve; 19. Third three-way valve; 20. Fourth three-way valve; 21. Fifth three-way valve; 22. Sixth three-way valve. DETAILED DESCRIPTION

[0028] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific implementation methods of the present application are described in detail below in conjunction with the accompanying drawings. In the following description, many specific details are set forth to facilitate a full understanding of the present application. However, the present application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar improvements without violating the connotation of the present application, so the present application is not limited by the specific embodiments disclosed below.

[0029] In the description of the present application, it should be understood that if the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc. appear, the orientation or position relationship indicated by these terms is based on the orientation or position relationship shown in the accompanying drawings, which is only for the convenience of describing the present application 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 cannot be understood as a limitation on the present application.

[0030] In addition, if the terms "first" or "second" appear, these terms are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of this application, if the term "plurality" appears, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0031] In this application, unless otherwise clearly specified and limited, if the terms "installed", "connected", "connected", "fixed" and the like appear, these terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integrated connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood according to the specific circumstances.

[0032] In the present application, unless otherwise clearly specified and limited, if there is a description that a first feature is "above" or "below" a second feature, etc., or similar descriptions appear, it may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Moreover, the first feature being "above", "above" and "above" the second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. The first feature being "below", "below" and "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0033] It should be noted that if an element is referred to as being "fixed to" or "disposed on" another element, it may be directly on the other element or there may be a central element. If an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be a central element at the same time. If any, the terms "vertical", "horizontal", "upper", "lower", "left", "right" and similar expressions used in this application are for illustrative purposes only and do not represent the only implementation method.

[0034] See also Figure 1 The first aspect of the present application provides a fuel cell device, comprising: a fuel cell stack 1, an air supply system, a hydrogen supply system, a retarder supply system 6 and a control system 16. The air supply system is directly connected to the fuel cell stack 1 to provide air to the fuel cell stack 1. The hydrogen supply system is directly connected to the fuel cell stack 1 to provide hydrogen to the fuel cell stack 1. The air supply system and the hydrogen supply system are also connected to the fuel cell stack 1 via the retarder supply system 6 to provide air and hydrogen carrying retarder gas to the fuel cell stack 1, respectively. The control system 16 is electrically connected to the fuel cell stack 1, the air supply system, the hydrogen supply system and the retarder supply system 6.

[0035] The air supply system includes an air compressor 2 and an air intercooler 3 .

[0036] The hydrogen supply system includes a hydrogen conveyor 4 and a nitrogen drainer 5 .

[0037] like Figure 2 As shown, the refrigerant supply system 6 includes a temperature-controllable electric heater 8, an integrally enclosed refrigerant introducer body 9, a cathode gas chamber partition 10 that encloses the left and right chambers, refrigerants 11 respectively enclosed in the left and right chambers, a hydrogen inlet pipe 14 and a hydrogen outlet pipe 15 that are connected to the chamber on one side of the refrigerant introducer body 9, and an air inlet pipe 12 and an air outlet pipe 13 that are connected to the chamber on the other side of the refrigerant introducer body 9.

[0038] The specific structural parameters of the retarder introducer body 9 do not require special design. Only its spatial volume (set as V: unit L) and controllable working temperature (set as T: unit ℃) meet the coupling related variables and are functionally related to the steam demand of the retarder 11 (set as n: unit mol).

[0039] The current density is increased by starting the stack at low temperature (set as Ⅰ: unit A / cm 2 ), active area of ​​the battery stack (set as S: unit cm 2 ) and the number of stack units (set to N) can be used to calculate the amount of reaction water.

[0040] The volume concentration of the retardant 11 (set as λ) slightly lower than the freezing point temperature of T1 can be obtained through the cold start temperature (set as T1: unit ℃) and the relationship curve between the volume concentration of the retardant 11 and the freezing point.

[0041] By fixing the physical parameters such as the molar mass and density of water and the retarder 11, the amount of retarder 11 vapor required to be below the freezing point T1 can be converted from the amount of reaction water.

[0042] According to the relationship formula of the saturated vapor pressure P of the substance and the temperature T, lgP=AB / (T+C) and the ideal gas formula PV=nRT, the function formula of the spatial volume V of the slow-freezing agent introducer body 9 and the freezing point temperature T1 and the controllable working temperature T can be obtained. Through this function, the slow-freezing agent 11 introducer adapted to different working temperature areas can be customized. The filling amount of the liquid slow-freezing agent 11 should not exceed 1 / 10 of the total volume of the slow-freezing agent introducer body 9b, so as not to occupy too much evaporation gas space.

[0043] The retarder 11 needs to be mutually soluble with the reaction generated water in the full concentration region and the freezing point in the mutual dissolution region is lower than that of pure water. At the same time, the retarder 11 is carried into the water vapor channels such as the three-phase reaction point and the gas diffusion layer through the standard reaction gas flow. Therefore, the retarder 11 needs to have a higher saturated vapor pressure and can produce a larger amount of retarder gas under the same conditions, saving the volume of the retarder introducer body 9 and reducing the generation temperature. The retarder 11 should not run for more than 30 minutes inside the fuel cell stack 1, so as not to affect the life of the fuel cell stack 1.

[0044] In some embodiments, the fuel cell device further includes a drain valve 7 for draining the waste gas / liquid generated after the fuel cell stack 1 reacts.

[0045] In some embodiments, the fuel cell device further includes a plurality of three-way valves for regulating the supply of air, hydrogen and slow-freezing gas.

[0046] The gas supply circuit structure of the fuel cell stack 1 is as follows Figure 1 As shown (the dotted line is the control signal sending and feedback loop, and the solid line is the gaseous, liquid, and solid material flow loop). First is the hydrogen supply system. On the one hand, the hydrogen transporter 4, the fuel cell stack 1, and the nitrogen drainer 5 are connected in sequence to form a first loop. Specifically, the outlet of the hydrogen transporter 4 is connected to the anode chamber inlet of the fuel cell stack through the first three-way valve 17; the anode chamber outlet of the fuel cell stack is connected to the inlet of the nitrogen drainer 5; the outlet of the nitrogen drainer 5 is connected to the inlet of the hydrogen transporter 4 through the third three-way valve 19. At the same time, the outlet of the nitrogen drainer 5 is also connected to the drain valve 7 through the fourth three-way valve 20 to drain the waste gas / liquid generated after the reaction.

[0047] On the other hand, the hydrogen conveyor 4, the retarder supply system 6, the fuel cell stack 1 and the nitrogen drainer 5 are connected in sequence to form a second loop. Specifically, the outlet of the hydrogen conveyor 4 is connected to the hydrogen inlet pipe 14 in the retarder supply system 6 through the second three-way valve 18, and then connected to the anode chamber inlet of the fuel cell stack through the hydrogen outlet pipe 15 in the retarder supply system 6; the anode chamber outlet of the fuel stack is connected to the inlet of the nitrogen drainer 5; the outlet of the nitrogen drainer 5 is connected to the inlet of the hydrogen conveyor 4 through the third three-way valve 19. At the same time, the outlet of the nitrogen drainer 5 is also connected to the drain valve 7 through the fourth three-way valve 20 to drain the waste gas / liquid generated after the reaction.

[0048] Next is the air supply system. On the one hand, the air compressor 2, the air intercooler 3, the retarder supply system 6, the fuel cell stack 1 and the drain valve 7 are connected in sequence. Specifically, the outlet of the air compressor 2 is connected to the input end of the air intercooler 3; the output end of the air intercooler 3 is connected to the air inlet pipe 12 in the retarder supply system 6 through the sixth three-way valve 22, and then connected to the cathode chamber inlet of the fuel cell stack through the air outlet pipe 13 in the retarder supply system 6; the cathode chamber outlet of the fuel cell stack is connected to the drain valve 7.

[0049] On the other hand, the air compressor 2, the air intercooler 3, the fuel cell stack 1 and the drain valve 7 are connected in sequence. Specifically, the outlet of the air compressor 2 is connected to the input end of the air intercooler 3; the output end of the air intercooler 3 is connected to the cathode chamber inlet of the fuel cell stack through the fifth three-way valve 21; the cathode chamber outlet of the fuel cell stack is connected to the drain valve 7.

[0050] As is known to all, when the storage temperature is > 0°C, the water inside the fuel cell stack 1 will not freeze. After the fuel cell stack 1 is shut down, it does not need to be drained or purged. It can be directly shut down and parked. When restarted, the standard gas supply strategy is adopted. It can be understood that the standard gas supply strategy refers to the introduction of hydrogen into the anode of the fuel cell stack 1 and the introduction of air into the cathode of the fuel cell stack 1.

[0051] Specifically, when the storage temperature is greater than 0°C, after the fuel cell stack 1 is shut down (the load is 0), the fuel cell stack 1 directly enters the parking state. When restarting, the fuel cell stack 1 adopts a standard gas supply strategy: open the first, third and fifth three-way valves 21, close the second, fourth and sixth three-way valves 22, and the hydrogen conveyor 4 conveys the standard working condition hydrogen into the anode gas inlet of the fuel cell stack 1, and the air compressor 2 conveys the standard working condition air into the cathode gas inlet of the fuel cell stack 1. After the stable working conditions are established inside the fuel cell stack 1, the external load is started, and the fuel cell stack 1 enters the normal working state. The remaining hydrogen after the reaction is discharged from the anode gas outlet of the fuel cell stack 1, and the water is separated through the nitrogen drainer 5, and the dehydrated hydrogen continues to circulate into the hydrogen conveyor 4 to participate in the stack work. After multiple cycles, when the concentration of nitrogen infiltrated into the hydrogen increases to a set value or the precipitated water reaches a limited height of the liquid level, the third three-way valve 19 is closed, the fourth three-way valve 20 is opened, and the mixed gas and liquid are emptied from the exhaust valve 7 through the nitrogen exhauster 5. The remaining air after the reaction is discharged from the cathode gas outlet of the fuel cell stack 1, and the air with water is directly emptied through the exhaust valve 7. The intake and exhaust are continuously regulated by the control system 16 to ensure the continuous operation of the fuel cell stack 1.

[0052] However, when the storage temperature is ≤0°C, the startup speed is slow and the startup is prone to failure when using standard reaction gas (standard gas supply strategy) at low temperature (≤0°C).

[0053] To solve the startup problem at low temperature, such as Figure 3 As shown, the second aspect of the present application provides a low temperature start-up method for a fuel cell device, the method comprising the following steps:

[0054] S1. After the fuel cell device is shut down, the standard gas supply strategy is used to drain and purge the inside of the fuel cell device. When the impedance measurement value (R1) of the fuel cell stack after purge gradually increases to reach the preset impedance R value, the gas supply is stopped and the device is parked;

[0055] S2, restart, measure the stack impedance (R2) before starting, when R2 is not higher than R1, adopt the standard gas supply strategy; when R2 is higher than R1, adopt the slow freezing gas supply strategy;

[0056] S3. When the fuel cell stack 1 is successfully started and the temperature rises to above 5° C., the reaction gas is switched to the standard reaction gas.

[0057] It can be understood that the slow-freezing gas supply strategy refers to introducing hydrogen with slow-freezing gas into the anode of the fuel cell stack 1 , and introducing air with slow-freezing gas into the cathode of the fuel cell stack 1 .

[0058] That is, when the cold start temperature is ≤0°C, the internal temperature of the fuel cell stack 1 will gradually drop to approach the ambient temperature as time goes by after the fuel cell stack 1 is shut down, and the moisture inside the fuel cell stack 1 will freeze and block the gas channel. Therefore, the fuel cell stack 1 needs to be drained and purged after shutdown. The drainage and purge adopts the standard gas supply strategy until the stack impedance measurement value (R1) after purging gradually increases to reach the set R value, and then the gas is stopped and parked.

[0059] The restart gas supply strategy after parking is related to the impedance of the fuel cell stack 1 after shutdown and purging: if the stack impedance (R2) before restarting is not higher than the measured impedance value (R1) of the stack after purging, it means that the heat inside the fuel cell stack 1 has not been completely consumed, and the reaction heat density of the fuel cell stack 1 is sufficient to resist the freezing trend of the generated water. At this time, the standard gas supply strategy can be used for startup. If the stack impedance (R2) before restarting is higher than the measured impedance value (R1) of the stack after purging, the restart needs to adopt the slow freezing gas supply strategy. The generated water of the fuel cell stack 1 is combined with the retarder 11, and the freezing point of the mixed liquid is lowered without freezing. It is discharged from the fuel cell stack 1 along with the reaction gas, which ensures the smooth operation of the new reaction gas inside the fuel cell stack 1 and the smooth startup of the fuel cell stack 1. Until the fuel cell stack 1 is successfully started and the temperature rises to above 5°C, the reaction gas is switched to the standard reaction gas without the retarder 11. With the circulation of gas and the emptying of gas and liquid, the components of the retarder 11 are quickly metabolized, which has almost no effect on the performance and life of the fuel cell stack 1.

[0060] Specifically, when the cold start temperature is ≤0°C and the fuel cell device is shut down, a standard gas supply strategy is used to drain and purge the interior of the fuel cell device. When the stack impedance measurement value (R1) after purge gradually increases to reach the preset impedance R value, the gas supply is stopped and the device is parked.

[0061] Restart, measure the stack impedance (R2) before starting, if R2≤R1, restart the stack using the standard gas supply strategy. When R2>R1, restart the stack using the slow freezing gas supply strategy, that is, set the working temperature T of the slow freezing agent introducer body 9 according to the cold start temperature T1, turn on the temperature controllable electric heater 8 to heat to the set temperature, open the second, third and sixth three-way valves 22, close the first, fourth and fifth three-way valves 21, and use the hydrogen conveyor 4 to transport the standard working condition hydrogen into the hydrogen inlet of the slow freezing agent introducer body 9 through the hydrogen inlet pipe 14, and the hydrogen carrying slow freezing gas enters the anode gas inlet of the fuel cell stack 1 through the hydrogen outlet pipe 15 of the slow freezing agent introducer body 9. Use the air compressor 2 to transport the standard working condition air into the air inlet of the slow freezing agent introducer body 9 through the air inlet pipe 12, and the air carrying slow freezing gas enters the cathode gas inlet of the fuel cell stack 1 from the air outlet pipe 13 of the slow freezing agent introducer. After establishing stable working conditions inside the stack, start the external load and the stack enters the working state. The remaining hydrogen after the reaction is discharged from the anode gas outlet of the fuel cell stack 1, and the water is separated through the nitrogen drainer 5. The dehydrated hydrogen continues to circulate into the hydrogen conveyor 4 to participate in the stack work. After multiple cycles, when the concentration of nitrogen infiltrated into the hydrogen rises to the set value or the precipitated water reaches the liquid level limit, the third three-way valve 19 is closed, the fourth three-way valve 20 is opened, and the mixed gas and liquid are emptied from the drain valve 7 through the nitrogen drainer 5. The remaining air after the reaction is discharged from the cathode gas outlet of the fuel cell stack 1, and the air with water is directly emptied through the drain valve 7. The intake and exhaust are continuously regulated by the control system 16, and the fuel cell stack 1 continues to operate.

[0062] When the outlet temperature of the coolant in the stack reaches 0°C, the refrigerant supply system is turned off and allowed to cool naturally. When the outlet temperature of the coolant in the fuel cell stack 1 reaches 5°C, the first and fifth three-way valves 21 are opened, the second and sixth three-way valves 22 are closed, the gas supply circuit is switched to the standard gas supply strategy, the reaction gas is switched to the standard reaction gas, and the standard hydrogen and air carry the residual refrigerant 11 components in the fuel cell stack 1 through continuous circulation and emptying until they are completely purified, and the fuel cell stack 1 enters a normal working state.

[0063] Among them, the setting and spatial volume V of the retarder introducer body 9 are determined based on the cold start temperature T1 of the product's purpose scenario, the space that the fuel cell device can accommodate, and the required heating temperature T of the retarder introducer body 9. In order to save energy and preheating time, the heating temperature T of the retarder introducer body 9 should not exceed 60°C. The retarder 11 is selected according to the characteristics that the retarder 11 is fully miscible with water, the miscible freezing point is lower than the cold start temperature T1, and the saturated vapor pressure is high, and the liquid retarder 11 is loaded into the retarder introducer body 9 not exceeding 1 / 10 of the total volume.

[0064] The following will provide a detailed description through the description of specific embodiments.

[0065] Example 1

[0066] The working environment of the fuel cell device is an area with a minimum temperature of 5°C. After the fuel cell stack is shut down (output demand = 0), the anode hydrogen circuit and the cathode air circuit are closed, and the fuel cell stack directly enters the parking state.

[0067] When the fuel cell stack is restarted after being shut down for 12 hours, a standard gas supply strategy is adopted: the first, third and fifth three-way valves are opened, and the second, fourth and sixth three-way valves are closed. The hydrogen conveyor conveys hydrogen under standard working conditions into the anode gas inlet of the fuel cell stack, and the air compressor conveys air under standard working conditions into the cathode gas inlet of the fuel cell stack. After stable working conditions are established inside the fuel cell stack, the time from starting the external load to the stack entering a stable working state is 1S.

[0068] Example 2

[0069] The working environment of the fuel cell device is in an area with a cold start temperature of T1 = -38°C. According to the cold start temperature T1 = -38°C, methanol is used as a refrigerant. The freezing point temperature of the mixed solution of methanol and water is T2 < -38°C. Take T2 = -40°C. According to the relationship curve between methanol volume concentration and freezing point, the volume concentration λ = 50% can be obtained. Methanol vapor demand n*M 甲醇 / ρ 甲醇 = Water production per unit time of stack startup*M 水 / ρ 水 . Substitute the physical parameter values ​​of methanol and water and the water production per unit time of the stack startup = Ⅰ (current density) * S * (active area) * N (number of stack pieces) * coulomb electron number * molar constant / 2 = 0.5 * 410 * 473 * 6.25 * 10^18 * 6.02 * 10^23 / 2, and calculate the methanol vapor demand n = 0.22 mol. According to the relationship formula of methanol saturated vapor pressure P and temperature T lgP = AB / (T + C), where A = 7.88, B = 1473, C = 230 and the ideal gas formula PV = nR (273 + T), when T = 60 ° C, V = 7.4L. Calculated based on the consumption of about 0.2L of methanol for each low-temperature start, pre-injection of 1L of methanol can meet the same frequency requirements as the hydrogenation of the whole vehicle. Therefore, the total volume of the main body of the retarder introducer only needs to meet 9L.

[0070] Gas supply strategy: After the fuel cell device is shut down (output demand = 0), the cold start temperature T1 = -38℃≤0℃, and the fuel cell device needs to be parked outdoors. Therefore, the anode hydrogen circuit and the cathode air circuit need to continue to operate. The standard gas supply strategy is implemented for the fuel cell device. The first, third and fifth three-way valves are opened, and the second, fourth and sixth three-way valves are closed. The hydrogen conveyor conveys standard working condition hydrogen into the anode gas inlet of the fuel cell stack, and the air compressor conveys standard working condition air into the cathode gas inlet of the fuel cell stack. The inside of the fuel cell device is drained and purged. Through the above-mentioned cyclic purge until the stack impedance measurement value R1 = 93mΩ ≥ R = 90mΩ, the standard gas supply purge stops.

[0071] After the fuel cell device was stopped for 5 hours without gas, the stack was restarted. Before starting, the stack impedance R2=75mΩ≤R1=93mΩ was measured, indicating that the temperature inside the stack had not dropped below 0°C, the residual water inside had not frozen, and the water generated by the re-reaction did not meet the conditions for freezing. Therefore, the standard gas supply strategy was used to restart the stack. After stable working conditions were established inside the stack, the external load was started and the stack entered the working state.

[0072] After working for a period of time, the fuel cell stack is shut down again according to demand (output demand = 0). The cold start temperature T1 = -38℃≤0℃. The fuel cell device still needs to be parked outdoors, so the anode hydrogen loop and the cathode air loop need to continue to operate. The standard gas supply strategy is implemented for the fuel cell device. Through the above-mentioned cycle purge until the stack impedance measurement value R1 = 97≥R = 90mΩ, the standard gas supply purge is stopped.

[0073] After the fuel cell device was stopped for 18 hours, the stack was restarted. Before starting, the stack impedance R2=120mΩ>R1=97mΩ was measured, indicating that the internal temperature of the stack had dropped below 0°C, the residual water inside had frozen and the water generated by the re-reaction had the conditions for freezing. Therefore, a slow-freezing gas supply strategy was required to restart the stack: the working temperature of the retarder introducer body was designed to be T=60°C based on T1=-38°C. After turning on the temperature-controllable heater to heat to the set temperature, the second, third and sixth three-way valves were opened, and the first, fourth and fifth three-way valves were closed. The hydrogen conveyor transported standard working condition hydrogen into the hydrogen inlet of the retarder introducer body through the hydrogen inlet pipe, and the hydrogen carrying the slow-freezing gas entered the anode gas inlet of the fuel cell stack through the hydrogen outlet pipe of the retarder introducer body. The air compressor delivers standard working condition air to the air inlet of the main body of the refrigerant introducer through the air inlet pipe, and the air carrying the refrigerant gas enters the cathode gas inlet of the fuel cell stack from the air outlet pipe of the refrigerant introducer. After the stable working conditions are established inside the stack, the external load is started and the stack enters the working state. After 12S, the outlet temperature of the stack coolant reaches 0℃, and the refrigerant supply system is turned off. After 25S, the outlet temperature of the stack coolant reaches 5℃, and the first, third, fourth and fifth three-way valves are opened, and the second and sixth three-way valves are closed. The gas supply circuit is switched to the standard gas supply strategy, and the residual methanol in the anode circuit is discharged from the anode gas outlet of the fuel cell stack with the hydrogen flow, and the mixed gas and liquid are emptied from the drain valve through the nitrogen drainer. The residual methanol in the cathode circuit is discharged from the cathode gas outlet of the fuel cell stack with the air flow and directly emptied through the drain valve. The standard hydrogen and air carry the residual methanol components inside the stack and are emptied within 30S through continuous circulation until they are completely purified. The third three-way valve is opened and the fourth three-way valve is closed, and the stack enters the normal working state.

[0074] Compared with the standard gas supply strategy under the same conditions, the slow-freezing gas supply strategy for low-temperature startup at -38°C shortened the startup time by 175 seconds, increased the startup speed by 87.5%, and increased the startup success rate by 100%, which was 50%. Since methanol has a short running time and fast metabolism in the fuel cell stack, the later life of the fuel cell stack was not affected.

[0075] Example 3

[0076] The working environment of the fuel cell device is the cold start temperature T1 = -15℃. According to the cold start temperature T1 = -15℃, ethanol is used as the refrigerant. The freezing point temperature of the mixed solution of ethanol and water is T2 < -15℃. Take T2 = -17℃. According to the relationship curve between ethanol volume concentration and freezing point, the volume concentration λ = 35%. Ethanol vapor demand n*M 乙醇 / ρ 乙醇 = Water production per unit time of stack startup*M 水 / ρ 水. Substitute the physical parameter values ​​of ethanol and water and the water production per unit time of the stack startup = Ⅰ (current density) * S * (active area) * N (number of stack pieces) * coulomb electron number * molar constant / 2 = 0.5 * 410 * 473 * 6.25 * 10^18 * 6.02 * 10^23 / 2, and calculate the ethanol vapor demand n = 0.084 mol. According to the relationship formula of ethanol saturated vapor pressure P and temperature T lgP = AB / (T + C), where A = 8.04, B = 1554, C = 223 and the ideal gas formula PV = nR (273 + T), select T = 50 ° C, V = 10.8L. Calculated based on the consumption of approximately 0.2L of methanol for each low-temperature start, pre-injection of 1L of methanol can meet the same frequency requirements as the hydrogenation of the whole vehicle. Therefore, the total volume of the main body of the retarder introducer only needs to meet 9L.

[0077] Gas supply strategy: After the fuel cell device is shut down (output demand = 0), the cold start temperature T1 = -15℃≤0℃, and the fuel cell system needs to be parked outdoors. Therefore, the anode hydrogen loop and the cathode air loop need to continue to operate. The standard gas supply strategy is implemented for the fuel cell device until the stack impedance measurement value R1 = 101 ≥ R = 90mΩ, and the standard gas supply purge is stopped.

[0078] After the fuel cell stack entered the parking state for 36 hours, it was restarted. Before starting, the stack impedance R2=105mΩ>R1=101mΩ was measured, indicating that the internal temperature of the stack had dropped below 0°C, the residual water inside had frozen and the water generated by the re-reaction had the conditions for freezing. Therefore, a slow-freezing gas supply strategy was required to restart the stack: the working temperature of the slow-freezing agent introducer body was designed to be T=50°C according to T1=-38°C, and after turning on the temperature-controllable heating heater to heat to the set temperature, the second, third and sixth three-way valves were opened, and the first, fourth and fifth three-way valves were closed. The hydrogen transporter transported standard working condition hydrogen into the hydrogen inlet of the slow-freezing agent introducer body through the hydrogen inlet pipe, and the hydrogen carrying slow-freezing gas entered the anode gas inlet of the fuel cell stack through the hydrogen outlet pipe of the slow-freezing agent introducer body. The air compressor delivers standard working condition air to the air inlet of the main body of the refrigerant introducer through the air inlet pipe, and the air carrying the refrigerant gas enters the cathode gas inlet of the fuel cell stack from the air outlet pipe of the refrigerant introducer. After the stable working conditions are established inside the stack, the external load is started and the stack enters the working state. After 10S, the outlet temperature of the stack coolant reaches 0°C, and the refrigerant supply system is turned off. After 22S, the outlet temperature of the stack coolant reaches 5°C, the first, third, fourth and fifth three-way valves are opened, the second and sixth three-way valves are closed, and the gas supply circuit is switched to the standard gas supply state. The residual ethanol in the anode circuit is discharged from the anode gas outlet of the fuel cell stack with the hydrogen flow, and the mixed gas and liquid are emptied from the drain valve through the nitrogen drainer. The residual ethanol in the cathode circuit is discharged from the cathode gas outlet of the fuel cell stack with the air flow and directly emptied through the drain valve. The standard hydrogen and air carry the residual ethanol components inside the stack and are emptied within 30S through continuous circulation until they are completely purified. The third three-way valve is opened and the fourth three-way valve is closed, and the stack enters the normal working state.

[0079] Compared with the standard gas supply strategy under the same conditions, the slow-freezing gas supply strategy for low-temperature startup at -15℃ shortened the startup time by 98 seconds, increased the startup speed by 81.7%, and achieved a 100% startup success rate, an increase of 24%. Since ethanol has a short running time and fast metabolism in the fuel cell stack, the fuel cell stack life was not affected in the later stage.

[0080] This application deeply analyzes the low-temperature startup mechanism of fuel cell stacks, sets up an antifreeze supply system in the fuel cell device, adds antifreeze (agent to reduce the freezing point of reaction water) to the standard gas supply, and uses gas carrying antifreeze to supply gas to the stack reaction at the initial stage of stack startup. After reaching a sufficiently high internal temperature of the stack, the standard gas supply strategy is switched to eliminate factors that affect the actual startup. The purpose of both lowering the freezing point and reducing the impact on the durability of the stack is achieved by optimizing the antifreeze component and designing the preparation parameters.

[0081] By adopting the low-temperature starting method provided in the present application, the starting speed of the battery stack can be increased by more than 80%, and the starting success rate can be as high as 100%.

[0082] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0083] The above-described embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be construed as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent application shall be subject to the attached claims.

Claims

1. A fuel cell device, characterized in that: include: A fuel cell stack, an air supply system, a hydrogen supply system, a retarder supply system and a control system; wherein the air supply system is directly connected to the fuel cell stack to provide air to the fuel cell stack; The hydrogen supply system is directly connected to the fuel cell stack to provide hydrogen to the fuel cell stack; The air supply system and the hydrogen supply system are also connected to the fuel cell stack via the retarder supply system, so as to respectively provide the fuel cell stack with air and hydrogen carrying retarder gas; The control system is electrically connected to the fuel cell stack, the air supply system, the hydrogen supply system and the refrigerant supply system.

2. The fuel cell device according to claim 1, characterized in that: The fuel cell device also includes a drain valve for draining the waste gas / liquid generated after the fuel cell stack reacts.

3. The fuel cell device according to claim 2, characterized in that: The air supply system includes an air compressor and an air intercooler; The air compressor, the air intercooler, the fuel cell stack and the exhaust valve are connected in sequence; At the same time, the air compressor and the air intercooler are also connected to the refrigerant supply system, the fuel cell stack and the exhaust valve in sequence.

4. The fuel cell device according to claim 2, characterized in that: The hydrogen supply system includes a hydrogen conveyor and a nitrogen drainer; The hydrogen transporter, the fuel cell stack and the nitrogen and water discharger are sequentially connected to form a first loop; At the same time, the hydrogen transporter, the retarder supply system, the fuel cell stack and the nitrogen and water exhauster are connected in sequence to form a second loop.

5. The fuel cell device according to claim 1, characterized in that: The tarnishing agent supply system includes a temperature-controllable electric heater, a tarnishing agent introducer body, anode and cathode gas chamber partitions, and tarnishing agent, wherein the temperature-controllable electric heater is used to heat the tarnishing agent introducer body; the tarnishing agent introducer body is divided into left and right chambers by the cathode and cathode gas chamber partitions; and the tarnishing agent is enclosed in the left and right chambers.

6. A low temperature start-up method for a fuel cell device, characterized in that: The following steps are involved: S1. After the fuel cell device is shut down, the standard gas supply strategy is used to drain and purge the inside of the fuel cell device. When the impedance measurement value (R1) of the fuel cell stack after purge gradually increases to reach the preset impedance R value, the gas supply is stopped and the device is parked; S2, restart, measure the stack impedance (R2) before starting, when R2 is not higher than R1, adopt the standard gas supply strategy; when R2 is higher than R1, adopt the slow freezing gas supply strategy; S3. When the fuel cell stack is successfully started and the outlet temperature of the coolant of the fuel cell stack rises to above 5° C., the reaction gas is switched to the standard reaction gas.

7. The low temperature starting method according to claim 6, characterized in that: Step S1 is specifically as follows: after the fuel cell device is shut down, the first, third and fifth three-way valves are opened, the second, fourth and sixth three-way valves are closed, and air is introduced into the cathode of the battery stack through the air supply system; hydrogen is introduced into the anode of the battery stack through the hydrogen supply system until R1=R, and then the gas is stopped and the stack is parked.

8. The low temperature starting method according to claim 6, characterized in that: In step S2, when R2 is higher than R1, the second, third and sixth three-way valves are opened, and the first, fourth and fifth three-way valves are closed, and air carrying defrosting gas is introduced into the cathode of the battery stack through the air supply system and the defrosting agent supply system; hydrogen carrying defrosting gas is introduced into the anode of the battery stack through the hydrogen supply system and the defrosting agent supply system.

9. The low temperature starting method according to claim 6, characterized in that: The following step is also included between step S2 and step S3: when the outlet temperature of the coolant of the fuel cell stack reaches 0°C, the retarder supply system is closed.

10. The low temperature starting method according to claim 6, characterized in that: The step S2 and / or S3 is followed by the following steps: when the concentration of nitrogen infiltrated into the hydrogen rises to a set value or the precipitated water reaches a limited height of the liquid level, the third three-way valve is closed, the fourth three-way valve is opened, and the mixed gas and liquid are drained from the drain valve through the nitrogen drainer.

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