Fuel cell stack ultralow-temperature cold starting method and system and vehicle

Abstract

The invention belongs to the technical field of fuel cells, and discloses a fuel cell stack ultralow-temperature cold starting method and system and a vehicle, and the fuel cell stack ultralow-temperature cold starting method comprises the following steps: S10, preparation before starting: opening a valve of an anode pipeline and a valve of a cathode pipeline of a stack; s20, electric pile preheating: supplying hydrogen to the anode of the electric pile, supplying nitrogen to the cathode of the electric pile, enabling the hydrogen and the nitrogen to react and discharge in the reaction cavity, and stopping supplying the hydrogen and the nitrogen until the outlet temperature of the cathode reaches a first preset temperature; hydrogen is supplied to the anode of the galvanic pile, and air is supplied to the cathode of the galvanic pile, so that the hydrogen and the air react in the reaction cavity for discharging until the temperature of the cooling liquid inlet reaches a second preset temperature. By using the ultralow-temperature cold start method for the fuel cell stack, ultralow-temperature cold start of the fuel cell stack can be realized, and meanwhile, the product does not contain liquid water, so that the safety and durability of the fuel cell stack during ultralow-temperature cold start are improved.

Description

Technical Field

[0001] The present invention relates to the field of fuel cell technology, and in particular to an ultra-low temperature cold start method for a fuel cell stack and a system and vehicle thereof. Background Art

[0002] As energy shortage and environmental pollution become increasingly serious, new energy vehicles are gradually developing, among which fuel cells are generally considered to have broad development prospects due to their high efficiency and near-zero emissions. Proton exchange membrane fuel cell (PEMFC) is a fuel cell that uses hydrogen and air as fuel to generate electricity. It does not require the combustion reaction of hydrogen and oxygen, but uses proton exchange membrane as electrolyte to directly convert the chemical energy of hydrogen and oxygen into electrical energy. It has the characteristics of high energy efficiency, zero emissions, low noise, and reliable continuous load operation. It can not only be used in special fields such as aerospace and military, but also has great market potential in fuel cell power stations, electric vehicles, and efficient portable power sources.

[0003] As for the problem that proton exchange membrane fuel cells cannot be started at ultra-low temperatures, the above ultra-low temperatures generally refer to ambient temperatures below -30°C, with an average temperature between -40°C and -50°C. When proton exchange membrane fuel cells operate at ultra-low temperature conditions, the water produced by the electrochemical reaction in the fuel cell freezes, reducing the electrochemical active area of ​​the catalyst layer and blocking the reaction gas channel, which in turn affects the battery performance, and ultimately leads to the failure of the battery to start at ultra-low temperatures and cannot operate normally. The formation of ice will also cause damage to the membrane electrode structure, affecting the battery life. In the prior art, an electric heater is often used to heat the coolant to achieve a successful cold start of the fuel cell stack, but the setting of the electric heater increases the structure and also increases the starting energy consumption of the fuel cell stack.

[0004] Therefore, there is an urgent need to develop a fuel cell stack ultra-low temperature cold start method and its system and vehicle to solve the above technical problems. Summary of the invention

[0005] One object of the present invention is to provide a fuel cell stack ultra-low temperature cold start method, which can achieve ultra-low temperature cold start of the fuel cell stack, and the product does not contain liquid water, thereby improving the safety and durability of the fuel cell stack during ultra-low temperature cold start.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A fuel cell stack ultra-low temperature cold start method comprises the following steps:

[0008] S10: Preparation before starting: Open the valve of the anode pipeline and the valve of the cathode pipeline of the fuel cell stack;

[0009] S20: preheating the stack: supplying hydrogen to the anode of the stack and nitrogen to the cathode, and causing the hydrogen and nitrogen to react and discharge in the reaction chamber until the cathode outlet temperature reaches a first preset temperature and then stopping the supply of hydrogen and nitrogen;

[0010] S30: Start the stack heating: supply hydrogen to the anode of the stack and air to the cathode, so that the hydrogen and air react and discharge in the reaction chamber until the coolant inlet temperature reaches a second preset temperature.

[0011] Optionally, before the hydrogen and nitrogen react and discharge in the reaction chamber, a first preset current is also loaded to the fuel cell stack.

[0012] Optionally, before the hydrogen and air react and discharge in the reaction chamber, a second preset current is also loaded to the fuel cell stack.

[0013] Optionally, the first preset current is I1, 10A≤I1≤60A; the second preset current is I2, 75A≤I2≤150A.

[0014] Optionally, after step S20 and before step S30, step S25 is performed: reducing the load of the fuel cell stack to a no-load state.

[0015] Optionally, the first preset temperature is T1, -30°C ≤ T1 ≤ -25°C; the second preset temperature is T2, -15°C ≤ T2 ≤ -5°C.

[0016] Optionally, after the fuel cell stack is shut down, step S100 is performed: shutdown purge: after the fuel cell stack is shut down, the anode chamber, cathode chamber and cooling chamber of the fuel cell stack are purged.

[0017] Optionally, the above-mentioned purging of the anode cavity, cathode cavity and cooling cavity of the above-mentioned fuel cell stack includes: introducing an inert gas into the anode cavity, cathode cavity and cooling cavity for purging.

[0018] Another object of the present invention is to provide a fuel cell stack ultra-low temperature cold start system, which executes the fuel cell stack ultra-low temperature cold start method described in any of the above-mentioned schemes, and the fuel cell stack ultra-low temperature cold start system includes a hydrogen supply device, a nitrogen supply device, an air supply device, a gas purge device, a DCDC module and a temperature collection device. The hydrogen supply device is connected to the anode of the above-mentioned stack through an anode pipeline with a valve, and the nitrogen supply device and the air supply device are both connected to the cathode of the above-mentioned stack through a cathode pipeline with a valve. The DCDC module is electrically connected to the above-mentioned stack, and the temperature collection device is configured to collect the temperatures of the anode inlet, anode outlet, cathode inlet, cathode outlet, coolant inlet and coolant outlet of the above-mentioned stack.

[0019] Another object of the present invention is to provide a vehicle, including the above-mentioned ultra-low temperature cold start system for a fuel cell stack, which can achieve ultra-low temperature cold start of the stack.

[0020] Beneficial effects of the present invention:

[0021] The present invention provides a method for ultra-low temperature cold start of a fuel cell stack and a system and a vehicle thereof. When the stack in the vehicle is ultra-low temperature cold started, a discharge reaction is first performed by hydrogen and nitrogen to preheat the stack without producing water. When the stack reaches a state where solid water is no longer produced, the stack is then switched to a discharge reaction of hydrogen and air to continue heating the stack until the stack reaches the cold start temperature to achieve successful start of the stack in an ultra-low temperature environment. This solution can be used to continuously heat the stack during the cold start of the stack, and liquid water will not be produced, and there is no risk of freezing, thereby improving the success rate of ultra-low temperature cold start of the fuel cell stack, and will not cause damage to the membrane electrode, thereby ensuring the durability and reliability of the ultra-low temperature cold start of the fuel cell stack, and no additional structure is added, with low start-up energy consumption and a simple structure. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the ultra-low temperature cold start method of a fuel cell stack of the present invention. DETAILED DESCRIPTION

[0023] The present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It is to be understood that the specific embodiments described herein are only used to explain the present invention, rather than to limit the present invention. It should also be noted that, for ease of description, only parts related to the present invention, rather than all structures, are shown in the accompanying drawings.

[0024] In the description of the present invention, unless otherwise clearly specified and limited, the terms "connected", "connected", and "fixed" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral 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. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0025] In the present invention, unless otherwise clearly specified and limited, a first feature being "above" or "below" a second feature may include that the first and second features are in direct contact, or may include that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, a first feature being "above", "above" and "above" a second feature includes that the first feature is directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. A first feature being "below", "below" and "below" a second feature includes that the first feature is directly below and obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0026] In the description of this embodiment, the terms "upper", "lower", "right", etc., directions or positional relationships are based on the directions or positional relationships shown in the drawings, and are only for the convenience of description and simplification of operation, rather than indicating or implying that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as limiting the present invention. In addition, the terms "first" and "second" are only used to distinguish in the description and have no special meaning.

[0027] In order to improve environmental protection, vehicles are currently gradually developing towards new energy. Vehicles using fuel cell systems are also a direction of development for new energy vehicles.

[0028] The vehicle includes a fuel cell system, which delivers energy to the vehicle to enable the vehicle to operate. The fuel cell stack is the core of the fuel cell system and is the part where electricity is generated. The fuel cell stack is composed of a stack of cathode sheets, membrane electrodes and anode sheets. The stack includes a cathode cavity, an anode cavity and a cooling cavity. The cooling cavity is used to pass coolant, the cathode cavity is used to pass air, and the anode cavity is used to pass hydrogen. The hydrogen in the hydrogen cavity and the air contact each other at the membrane electrode and undergo an electrochemical reaction to produce water.

[0029] During the use of fuel cell stacks, they may encounter ultra-low temperature conditions. For example, in the winter in the north, if the vehicle is parked outside, the temperature of the fuel cell stack will drop to an ultra-low temperature state. At this time, the product water will freeze, causing the problem of starting failure. At present, the ultra-low temperature cold start method for fuel cell stacks is a technical difficulty in this field. It should be noted that the ultra-low temperature is not higher than -30℃. Generally, the ultra-low temperature range is between -40℃ and -50℃.

[0030] In order to solve the above technical problems, the present embodiment provides a vehicle, which includes a fuel cell stack ultra-low temperature cold start system to achieve ultra-low temperature cold start of the vehicle. At the same time, the product does not contain liquid water, thereby improving the safety and durability of the fuel cell stack during ultra-low temperature cold start.

[0031] Specifically, the present embodiment provides a fuel cell stack ultra-low temperature cold start system, which includes a hydrogen supply device, a nitrogen supply device, an air supply device, a gas purge device, a DCDC module (i.e., a DC converter module), and a temperature acquisition device. The hydrogen supply device is connected to the anode of the stack through an anode pipeline with a valve, and the hydrogen supply device is used to supply hydrogen to the anode of the stack; the nitrogen supply device and the air supply device are both connected to the cathode of the stack through a cathode pipeline with a valve, and the nitrogen supply device is used to supply nitrogen to the cathode of the stack, and the air supply device is used to supply air to the cathode of the stack; the DCDC module is electrically connected to the stack, and can reversely load current to the stack; the temperature acquisition device is configured to collect the temperature of the anode inlet, anode outlet, cathode inlet, cathode outlet, coolant inlet, and coolant outlet of the stack. Through the above system, the stack can be ultra-low temperature cold started.

[0032] Furthermore, the ultra-low temperature cold start system for the fuel cell stack also includes a control device, which is electrically connected to the hydrogen supply device, the nitrogen supply device, the air supply device, the gas purge device, the DCDC module and the temperature acquisition device, and can realize the switching of the above-mentioned structure to achieve the ultra-low temperature cold start of the fuel cell stack.

[0033] The present embodiment also provides a fuel cell stack ultra-low temperature cold start method, which can achieve the cold start of the fuel cell stack in an ultra-low temperature environment by using the fuel cell stack ultra-low temperature cold start system, ensuring that the products generated by the operation of this scheme do not contain liquid water, thereby improving the safety and durability of the fuel cell stack during ultra-low temperature cold start.

[0034] Specifically, if Figure 1 As shown, when the vehicle is started, it is necessary to first determine whether the current temperature of the fuel cell stack is within the ultra-low temperature range. The temperature acquisition device can detect whether the temperature of the fuel cell stack is within the ultra-low temperature range. When the fuel cell stack is in an ultra-low temperature state, an ultra-low temperature cold start is required to ensure that the fuel cell stack will not freeze when it is started. The ultra-low temperature cold start method of the fuel cell stack includes steps S10 to S30, which are as follows:

[0035] S10: Preparation before starting: Open the valve of the anode pipeline and the valve of the cathode pipeline of the fuel cell stack to ensure that the gas path of the fuel cell stack is normal to facilitate subsequent work.

[0036] S20: Preheating the stack: hydrogen is supplied to the anode of the stack and nitrogen is supplied to the cathode, so that hydrogen and nitrogen react and discharge in the reaction chamber until the cathode outlet temperature reaches a first preset temperature and then the supply of hydrogen and nitrogen is stopped. This step is used to preheat the stack by the heat generated by the discharge reaction of hydrogen and nitrogen, and since the reaction of hydrogen and nitrogen does not produce water, it can be ensured that the stack will not freeze in the ultra-low temperature environment.

[0037] Optionally, the first preset temperature is T1, -30°C ≤ T1 ≤ -25°C, which is the temperature range value of T1, and the specific value can be determined according to actual needs.

[0038] Optionally, the first preset temperature T1 is the temperature required for all water produced by the reaction of hydrogen and air to be directly heated from liquid water to gaseous water, that is, after reaching the first preset temperature T1, the temperature generated by the reaction discharge of hydrogen and air is T3. Under the action of T1 and T3, all liquid water produced by hydrogen and air is directly vaporized, thereby ensuring that no liquid water appears in the battery stack, and further ensuring that the battery stack does not freeze.

[0039] Further optionally, before the hydrogen and nitrogen react and discharge in the reaction chamber, a first preset current is loaded into the battery stack. The loading of the first preset current can promote the hydrogen and nitrogen to react and discharge in the reaction chamber, thereby gradually increasing the temperature of the battery stack until it reaches T1.

[0040] Optionally, the first preset current is I1, 10A≤I1≤60A, which is the current range value of I1, and the specific value can be determined according to actual needs.

[0041] Optionally, the cathode outlet temperature reaches the first preset temperature T1 because during the operation of the fuel cell stack, the products of the reaction between hydrogen and air in the reaction chamber flow toward the cathode outlet or the anode outlet, and the cathode is the side where air flows, so there is more liquid water at the cathode outlet. When the temperature at the cathode outlet reaches the first preset temperature T1, it can be ensured that liquid water will not appear in the fuel cell stack, thereby ensuring that the fuel cell stack will not freeze.

[0042] Step S25: Reduce the load of the battery stack to the no-load state. Since the reaction gas in the reaction chamber needs to be replaced with hydrogen and air, the current needs to be reduced to the no-load state to end the discharge reaction between hydrogen and nitrogen. It should be noted that the no-load state refers to when the external output load of the battery stack is 0A.

[0043] S30: Stack heating start: hydrogen is supplied to the anode of the stack and air is supplied to the cathode, so that hydrogen and air react and discharge in the reaction chamber until the coolant inlet temperature reaches the second preset temperature. This step is used to heat the stack through the discharge reaction of hydrogen and air, and since the stack has already satisfied the hydrogen and air discharge reaction through the stack preheating, all liquid water can be directly converted into gaseous water, and no freezing will occur. When the temperature continues to rise until the coolant inlet temperature reaches the second preset temperature, the stack can be successfully cold-started at ultra-low temperature.

[0044] Optionally, the second preset temperature is a temperature at which liquid water will no longer freeze. Optionally, the second preset temperature is T2, -15°C ≤ T2 ≤ -5°C. Within this range, liquid water generated by the reaction of hydrogen and air will no longer freeze. This is the temperature range value of T2, and the specific value can be determined according to actual needs.

[0045] Further optionally, before the hydrogen and air react and discharge in the reaction chamber, a second preset current is loaded to the battery stack. The loading of the second preset current can promote the hydrogen and air to react and discharge in the reaction chamber, thereby gradually increasing the temperature of the battery stack until it reaches T2.

[0046] Optionally, the second preset current is I2, 75A≤I2≤150A, which is the current range value of I2, and the specific value can be determined according to actual needs.

[0047] Optionally, the above-mentioned coolant inlet temperature reaches the second preset temperature T2 because hydrogen and air react in the reaction chamber, the temperature on the outlet side is higher than that on the inlet side, and the coolant inlet is not connected to the reaction chamber. Therefore, when the coolant inlet reaches the second preset temperature T2, the temperature at each position of the fuel cell stack meets the second preset temperature T2.

[0048] Furthermore, after the stack is shut down, step S100 is performed: shutdown purge: after the stack is shut down, the anode cavity, cathode cavity and cooling cavity of the stack are purged. That is, after each operation of the stack, the anode cavity, cathode cavity and cooling cavity of the stack need to be purged to remove the liquid in the anode cavity, cathode cavity and cooling cavity, especially the water, so as to avoid the water inside the stack directly freezing in the ultra-low temperature environment when the stack is shut down, which affects the next startup of the stack.

[0049] Specifically, purging the anode cavity, cathode cavity and cooling cavity of the fuel cell stack includes: introducing inert gas into the anode cavity, cathode cavity and cooling cavity for purging. The inert gas is not easy to react, which can not only ensure that each cavity in the fuel cell stack is purged to remove excess liquid, but also ensure that no new products are generated, thereby improving the reliability of the gas purging device.

[0050] Optionally, nitrogen is selected as the inert gas, and no other gas supply device is needed.

[0051] The ultra-low temperature cold start method of the fuel cell stack of this embodiment, when the stack in the vehicle is ultra-low temperature cold started, firstly discharges hydrogen and nitrogen to preheat the stack without producing water, and when it reaches a state where no solid water is produced, then switches to hydrogen and air discharge reaction, continues to heat the stack, and until the stack reaches the cold start temperature, the ultra-low temperature environment of the stack can be successfully started. Through this scheme, during the cold start process of the stack, not only can the stack be continuously heated, but liquid water will not be produced, and there is no risk of freezing, which improves the success rate of ultra-low temperature cold start of the fuel cell stack, and will not cause damage to the membrane electrode, ensuring the durability and reliability of the ultra-low temperature cold start of the fuel cell stack, and no additional structure is added, the starting energy consumption is low, and the structure is simple.

[0052] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, various obvious changes, readjustments and substitutions can be made without departing from the protection scope of the present invention. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for ultra-low temperature cold start of a fuel cell stack, characterized in that: The following steps are involved: S10: Preparation before starting: Open the valve of the anode pipeline and the valve of the cathode pipeline of the fuel cell stack; S20: preheating the stack: supplying hydrogen to the anode of the stack and nitrogen to the cathode, and causing the hydrogen and nitrogen to react and discharge in the reaction chamber until the cathode outlet temperature reaches a first preset temperature and then stopping the supply of hydrogen and nitrogen; S30: stack heating start: hydrogen is supplied to the anode of the stack and air is supplied to the cathode, so that the hydrogen and air react and discharge in the reaction chamber until the coolant inlet temperature reaches a second preset temperature.

2. The ultra-low temperature cold start method for a fuel cell stack according to claim 1, characterized in that: Before the hydrogen and nitrogen react and discharge in the reaction chamber, a first preset current is also loaded to the battery stack.

3. The ultra-low temperature cold start method for a fuel cell stack according to claim 2, characterized in that: Before the hydrogen and air react and discharge in the reaction chamber, a second preset current is also loaded to the battery stack.

4. The ultra-low temperature cold start method for a fuel cell stack according to claim 3, characterized in that: The first preset current is I1, 10A≤I1≤60A; the second preset current is I2, 75A≤I2≤150A.

5. The ultra-low temperature cold start method for a fuel cell stack according to claim 3, characterized in that: After step S20 and before step S30, step S25 is performed: reducing the load of the fuel cell stack to a no-load state.

6. The ultra-low temperature cold start method for a fuel cell stack according to claim 1, characterized in that: The first preset temperature is T1, -30°C ≤ T1 ≤ -25°C; the second preset temperature is T2, -15°C ≤ T2 ≤ -5°C.

7. The ultra-low temperature cold start method for a fuel cell stack according to any one of claims 1 to 6, characterized in that: After the fuel cell stack is shut down, step S100 is performed: shutdown purge: after the fuel cell stack is shut down, the anode chamber, cathode chamber and cooling chamber of the fuel cell stack are purged.

8. The ultra-low temperature cold start method for a fuel cell stack according to claim 7, characterized in that: The purging of the anode cavity, cathode cavity and cooling cavity of the stack includes: introducing an inert gas into the anode cavity, cathode cavity and cooling cavity for purging.

9. Ultra-low temperature cold start system for fuel cell stack, characterized in that: A fuel cell stack ultra-low temperature cold start method as described in any one of claims 1 to 8 is performed, wherein the fuel cell stack ultra-low temperature cold start system includes a hydrogen supply device, a nitrogen supply device, an air supply device, a gas purge device, a DCDC module and a temperature acquisition device, the hydrogen supply device is connected to the anode of the stack through an anode pipeline with a valve, the nitrogen supply device and the air supply device are both connected to the cathode of the stack through a cathode pipeline with a valve, the DCDC module is electrically connected to the stack, and the temperature acquisition device is configured to acquire the temperatures of the anode inlet, anode outlet, cathode inlet, cathode outlet, coolant inlet and coolant outlet of the stack.

10. A vehicle, characterized in that It includes the ultra-low temperature cold start system for a fuel cell stack as described in claim 9.

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