Cold start method for fuel cell system

Abstract

The invention relates to a fuel cell system cold start method which comprises the following steps: at an ambient temperature, air introduced into a reactor reacts with a reduced metal catalyst to obtain an oxidized metal catalyst, the oxidized metal catalyst releases heat, the heat heats a power cell and a fuel cell stack, and meanwhile, the power cell heats the fuel cell stack; tail gas generated by the reaction enters a fuel cell stack to be heated; when the temperature of the fuel cell stack is higher than 0 DEG C due to heating, introducing air and hydrogen into the fuel cell stack, and discharging to enable the fuel cell stack to generate heat; and when the temperature of the fuel cell stack continues to rise to the working temperature due to the heat, hydrogen of the fuel cell stack is introduced into the reactor to react with the oxidation-state metal catalyst to generate a reduction-state metal catalyst, and the cold start of the fuel cell system is realized after the reaction is finished. According to the invention, the fuel cell stack and the power cell are heated in a manner that air reacts with the reduction-state metal catalyst to release heat, and non-power cold start can be realized under the extremely cold condition of-50 DEG C.

Description

Technical Field

[0001] This invention belongs to the fields of electrochemistry and thermochemistry, and specifically relates to a cold start method for a fuel cell system. Background Technology

[0002] The cold-start performance of fuel cell systems in low-temperature environments is one of the key technological bottlenecks restricting their commercial application. In operating conditions below 0°C, water generated inside a proton exchange membrane fuel cell (PEMFC) is prone to phase change and freezing, leading to reduced catalyst activity, hindered diffusion of reactant gases, and even damage to the membrane electrode structure, severely impacting system start-up efficiency and durability. Existing cold-start technologies mainly rely on external electric heating or self-generated heat from the fuel cell stack, but these have significant limitations: electric heating consumes a large amount of onboard electrical energy, reducing system energy density; while self-generated heat from the fuel cell stack can cause irreversible damage to the membrane and catalyst, making it difficult to meet the requirements of large-scale applications. Furthermore, existing technologies often focus on a single heat source (such as self-generated heat from the fuel cell stack or external heat input), failing to fully realize the thermal management coupling design between the power battery and the fuel cell, resulting in high cold-start energy consumption and insufficient heating rate. To address these issues, there is an urgent need to develop an efficient, reliable, and compact cold-start technology that overcomes the technical barriers to rapid fuel cell start-up in low-temperature environments through multi-heat source synergistic heating and energy cascade utilization, while simultaneously considering system energy efficiency and economy. Summary of the Invention

[0003] To overcome the aforementioned problems in the prior art, the present invention provides a cold start method for a fuel cell system, which solves the problems existing in the prior art.

[0004] A cold start method for a fuel cell system, the fuel cell system comprising a power battery, a reactor, and a fuel cell stack, wherein the inlet of the reactor is connected to external air, and the outlet is connected to the power battery and the fuel cell stack; the power battery is simultaneously connected to the fuel cell stack, the method comprising:

[0005] S1. At ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain an oxidized metal catalyst and releases heat. The released heat is used to heat the power battery and fuel cell stack. At the same time, the power battery heats the fuel cell stack by electric heating.

[0006] S2. The exhaust gas produced by the reaction enters the fuel cell stack from the reactor for heating;

[0007] S3. When heating causes the temperature of the fuel cell stack to be higher than 0°C, air and hydrogen are introduced into the fuel cell stack, and the fuel cell stack is discharged under constant current or constant voltage to generate heat.

[0008] S4. When the heat makes the fuel cell stack temperature continue to rise to its working temperature, the hydrogen of the fuel cell stack is fed into the reactor to react with the oxidized metal catalyst to generate the reduced metal catalyst, the reaction is over, and the cold start of the fuel cell system is realized.

[0009] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein the reactor inlet pipeline is provided with a first valve for controlling the feeding of air, two branch pipelines are arranged at the outlet, a second valve is arranged on the first branch pipeline for controlling the discharge of tail gas, and the second branch pipeline is connected to the fuel cell stack and provided with a third valve.

[0010] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein the ambient temperature is -50°C to room temperature.

[0011] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein the fuel cell stack comprises two inlets and two outlets, the first inlet is connected to the second branch pipeline, and a fourth valve is arranged on the pipeline connected to the inlet for feeding air; a fifth valve is arranged on the pipeline connected to the second inlet for feeding hydrogen; the first outlet is connected to the ambient atmosphere, and the second outlet is connected to the inlet pipeline of the reactor through a pipeline and provided with a sixth valve for controlling the feeding of hydrogen into the reactor.

[0012] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein the reduced metal catalyst is a copper-based catalyst, preferably a copper-zinc-aluminum catalyst or a copper-aluminum catalyst.

[0013] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein S4 further comprises:

[0014] When the reduced metal catalyst in the reactor is completely converted into the oxidized metal catalyst, and the fuel cell stack temperature is not raised to above 0°C, the continuous heating of the fuel cell stack is realized through the following three manners:

[0015] Manner one: the fuel cell stack is continuously heated to above 0°C by the power battery through electric heating, and then air and hydrogen are fed into the fuel cell stack through the two inlets, and the stack is discharged under constant current or constant voltage to generate heat, so that the fuel cell stack temperature is raised to its working temperature;

[0016] Manner two: air and hydrogen are directly fed into the fuel cell stack through the two inlets, and the stack is discharged under constant current or constant voltage to generate heat, so that the fuel cell stack temperature is raised to its working temperature;

[0017] The third way: the power battery continues to heat the fuel cell stack by electric heating, and air and hydrogen are introduced into the fuel cell stack, and the stack generates heat under constant current or constant voltage to make the stack temperature rise to its working temperature.

[0018] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein the fuel cell system further comprises a cooling liquid storage tank, which is connected to the reactor, the power battery and the fuel cell stack.

[0019] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein S1 is specifically that, at ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain oxidized metal catalyst and release heat, the released heat is used to heat the cooling liquid in the cooling liquid storage tank, and the heated cooling liquid is introduced into the fuel cell stack to heat the fuel cell stack and the power battery, and the tail gas of the reactor enters the fuel cell stack to heat the stack.

[0020] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein S4 comprises the following three ways when the reduced metal catalyst in the reactor is completely converted into oxidized metal catalyst and the temperature of the fuel cell stack is not raised to above 0℃:

[0021] The first way: the power battery continues to heat the fuel cell stack by electric heating to above 0℃, and then air and hydrogen are introduced into the fuel cell stack through the fourth valve and the fifth valve, and the stack generates heat under constant current or constant voltage to make the temperature of the fuel cell stack rise to its working temperature;

[0022] The second way: air and hydrogen are directly introduced into the fuel cell stack through the fourth valve and the fifth valve, and the fuel cell stack generates heat under constant current or constant voltage to make the temperature of the fuel cell stack rise to its working temperature;

[0023] The third way: the power battery continues to heat the fuel cell stack by electric heating, and air and hydrogen are introduced into the fuel cell stack through the fourth valve and the fifth valve, and the stack generates heat under constant current or constant voltage to make the temperature of the fuel cell stack rise to its working temperature.

[0024] According to the aspect and any possible implementation manner described above, further provided is an implementation manner, wherein during the process of introducing air and hydrogen into the fuel cell stack, the third valve is opened to introduce the tail gas into the fuel cell stack together with the air, or the third valve is closed and the second valve is opened to discharge the tail gas to the environment.

[0025] Advantages of the present application

[0026] The fuel cell system cold starting method of the present application, the fuel cell system comprises a power battery, a reactor and a fuel cell stack, wherein the inlet of the reactor is connected with external air, and the outlet is connected with the power battery and the fuel cell stack; the power battery is connected with the fuel cell stack at the same time, the method comprises the following steps: at ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain oxidized metal catalyst and releases heat, the released heat is used to heat the power battery and the fuel cell stack, at the same time, the power battery heats the fuel cell stack by electric heating; the tail gas generated by the reaction enters the fuel cell stack to heat; when the heating makes the temperature of the fuel cell stack higher than 0℃, air and hydrogen are introduced into the fuel cell stack, and the fuel cell stack is discharged under constant current or constant voltage to generate heat; when the heat makes the temperature of the fuel cell stack continue to rise to its working temperature, the hydrogen of the fuel cell stack is introduced into the reactor to react with the oxidized metal catalyst to generate reduced metal catalyst, and the reaction is ended to realize the cold starting of the fuel cell system. The present application has the following advantages: technical safety, convenience, flexibility, reliability, good economy and the like; the air and reduced metal catalyst reaction heat release mode is used to heat the fuel cell stack and the power battery, and the cold starting without power can be realized; the method can realize the extremely low temperature cold starting under-50℃ environment, and has more excellent low temperature cold starting characteristics; and the chemical chain combustion reaction is fast, the heat release is large, and the cold starting time is faster. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 Figure 1 is a schematic diagram of the structure of the fuel cell system of the present application;

[0028] Figure 2 Figure 2 is a schematic diagram of the structure of the fuel cell system of the present application. DETAILED DESCRIPTION

[0029] In order to better understand the technical solutions of the present application, the present application includes but is not limited to the specific embodiments in the following, similar technologies and methods should be regarded as within the scope of protection of the present application. In order to make the technical problems, technical solutions and advantages solved by the present application more clear, the following will be described in detail in combination with the drawings and specific embodiments.

[0030] It should be clear that the embodiments described in the present application are only a part of the embodiments of the present application, not all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0031] The terminology used in the description of the application herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in the description of the application and the appended claims, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise.

[0032] As shown in the drawings, Figure 1 The fuel cell system of the present application comprises a power battery 2, a reactor 1 and a fuel cell stack 3. The power battery 2 is used to provide additional power when the fuel cell system is cold started, accelerated, etc. high power demand, and to recover and store excess power when the load is low or braking; the reactor 1 provides heat for the cold start process of the fuel cell system for system warming to achieve cold start, and the fuel cell stack 3 is the core power generation unit of the fuel cell system, which continuously generates electricity through hydrogen-oxygen chemical reaction. Among them, the inlet of the reactor 1 is connected with external air, and the outlet is connected with the power battery 2 and the fuel cell stack 3; the power battery 2 is connected with the fuel cell stack 3. A first valve 8 is arranged on the inlet pipeline of the reactor 1 for controlling the inlet of air, and two branch pipelines are arranged at the outlet, a second valve 9 is arranged on the first branch pipeline for controlling the exhaust gas, which is discharged into the environment, and a second branch pipeline is connected with the fuel cell stack 3 and provided with a third valve 4. The fuel cell stack 3 comprises two inlets and two outlets, the first inlet is connected with the second branch pipeline, and a fourth valve 5 is arranged on the pipeline connected with the inlet for inlet of air; a fifth valve 6 is arranged on the pipeline connected with the second inlet for inlet of hydrogen; the first outlet is communicated with the environment, and the second outlet is connected with the inlet pipeline of the reactor 1 through a pipeline, and a sixth valve 7 is arranged on the pipeline for controlling the inlet of hydrogen into the reactor 1.

[0033] As shown in the drawings, Figure 2 In another embodiment, the fuel cell system further comprises a cooling liquid storage tank 10 for storing cooling liquid, the cooling liquid in the cooling liquid storage tank is used as a heat exchange medium, which is first heated by the reactor 1, and then the cooling liquid is used to heat the power battery 2 and the fuel cell stack 3. The cooling liquid storage tank 10 is connected with the reactor 1, the power battery 2 and the fuel cell stack 3.

[0034] The fuel cell system of the present application, the cold start method comprises:

[0035] S1. At ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain an oxidized metal catalyst and releases heat, the released heat is used to heat the power battery and the fuel cell stack, and the power battery heats the fuel cell stack by electric heating;

[0036] S2. The tail gas generated by the reaction enters the fuel cell stack for heating;

[0037] S3. When the heat makes the temperature of the fuel cell stack higher than 0℃, air and hydrogen are introduced into the fuel cell stack, and the fuel cell stack is discharged at a constant current or a constant voltage to generate heat, and the fuel cell stack generates heat during discharging, which can be used to heat the stack to realize cold start. The constant current or constant voltage discharge is used to avoid the problem of excessive current and damage to the stack or failure of cold start. Therefore, the current setting range is 0.05-0.5A / cm 2 , and the voltage needs to be higher than 0.6V of the single cell of the stack;

[0038] S4. When the heat makes the temperature of the fuel cell stack continue to rise to its working temperature, the hydrogen of the fuel cell stack is introduced into the reactor to react with the oxidized metal catalyst to generate the reduced metal catalyst, and the reaction is completed to realize the cold start of the fuel cell system, which also includes: when the reduced metal catalyst in the reactor is completely converted into the oxidized metal catalyst, and the temperature of the fuel cell stack is not raised to above 0℃, the following three ways are used to continue to heat the fuel cell stack:

[0039] Method one: the power battery continues to heat the fuel cell stack to above 0℃ by electric heating, and then air and hydrogen are introduced into the fuel cell stack through two inlets, and the stack is discharged at a constant current or a constant voltage to generate heat, so that the temperature of the fuel cell stack rises to its working temperature. This method uses electric heating to heat the stack to above 0℃, and then uses the self-heating method of air and hydrogen entering the stack to generate electricity to continue to heat the stack, realizes the cold start of the fuel cell system, and avoids the problem of cold start failure caused by icing and other phenomena when the fuel cell stack is below 0℃. However, this method has the disadvantage of consuming additional electric energy.

[0040] Method two: without using the electric heating of the power battery, air and hydrogen are directly introduced into the fuel cell stack through two inlets, and the stack is discharged at a constant current or a constant voltage to generate heat, so that the temperature of the fuel cell stack rises to its working temperature. This method uses the self-heating method of air and hydrogen entering the stack to generate electricity to continue to heat the stack, realizes the cold start of the fuel cell system, and reduces the power consumption during the cold start process. However, it increases the control difficulty and the risk of cold start failure during the cold start process.

[0041] Method three: the power battery continues to heat the fuel cell stack by electric heating, while air and hydrogen are introduced into the fuel cell stack, and the stack is discharged at a constant current or constant voltage to generate heat, when the stack temperature rises above 0°C, the electric heating of the power battery is turned off, and the stack temperature is raised to its working temperature by continuing to introduce air and hydrogen into the stack for discharging and self-heating. This method can further reduce the cold start time, realize the cold start of the fuel cell system, and reduce the energy consumption of the power battery, but requires more complex control method.

[0042] The above-mentioned methods one, two and three are used on the premise that the temperature of the fuel cell stack is not raised above 0°C. Method one is to raise the temperature of the stack to above 0°C by electric heating, then turn off the electric heating of the power battery, and continue to introduce air and hydrogen into the stack to raise the temperature to the working temperature of the stack. Method three is to raise the temperature of the stack to above 0°C by electric heating and introducing air and hydrogen into the stack, then turn off the electric heating of the power battery, and continue to introduce air and hydrogen into the stack to raise the temperature to the working temperature of the stack.

[0043] Method one requires additional power consumption to raise the temperature of the stack. Method two uses the power generated by the stack to produce heat for self-heating of the stack to raise the temperature of the stack, but the control is complex. Method three is a combination of the first two methods, which can achieve the fastest cold start. When the cooling liquid storage tank 10 is provided, S1 in the start-up method is: at ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain oxidized metal catalyst and releases heat, the released heat is used to heat the cooling liquid in the cooling liquid storage tank, and the heated cooling liquid is introduced into the fuel cell stack to heat the fuel cell stack. The cooling liquid in the cooling liquid storage tank heats the power battery, and the tail gas of the reactor enters the fuel cell stack to heat the stack.

[0044] When the reduced metal catalyst in the reactor is completely converted into oxidized metal catalyst, and the temperature of the fuel cell stack is not raised above 0°C, the temperature of the fuel cell stack is raised by the following three methods. At this time, no cooling liquid storage tank is involved, and the specific methods are as follows:

[0045] Method one: the power battery continues to heat the fuel cell stack to above 0°C by electric heating, then air and hydrogen are introduced into the fuel cell stack through two inlets, and the stack is discharged at a constant current or constant voltage to generate heat, so that the temperature of the fuel cell stack rises to its working temperature;

[0046] Method two: directly introduce air and hydrogen into the fuel cell stack through two inlets, and discharge the stack at a constant current or constant voltage to generate heat, so that the temperature of the fuel cell stack rises to its working temperature;

[0047] Method 3: The power battery continues to heat the fuel cell stack through electric heating, while air and hydrogen are introduced into the fuel cell stack, and the stack is discharged under constant current or constant voltage to generate heat, raising the stack temperature to its operating temperature.

[0048] This invention utilizes a chemical looping combustion method, where the fuel cell stack and power battery are heated by the exothermic reaction of air with a reduced-state metal catalyst, enabling cold starts of the fuel cell system in ambient temperatures ranging from -50°C to 0°C. This system requires no electricity for startup, and the rapid chemical looping combustion reaction generates significant heat, allowing for quick cold starts of the fuel cell system and exhibiting superior adaptability to extreme low-temperature cold starts.

[0049] The following specific examples illustrate this:

[0050] against Figure 1 The cold start procedure of the fuel cell system shown includes the following steps: When the ambient temperature is between -50°C and 0°C, if the fuel cell system directly generates electricity, the water generated at the cathode of the fuel cell stack will freeze, blocking the flow channels and causing damage to the stack, or even preventing continuous or stable power generation. In this case, valves 8 and 4 are opened to introduce air into reactor 1 (this air can come from an air cylinder or be supplied by a battery-driven air pump). The air reacts with the reduced metal catalyst in reactor 1, releasing heat. The released heat is used to heat the power battery 2. The exhaust gas from reactor 1 enters the cathode flow channel of fuel cell stack 3 to heat the stack. When the temperature of fuel cell stack 3 is above 0°C, valves 5 and 6 are opened to introduce air and hydrogen into fuel cell stack 3, and the stack is discharged under constant current or constant voltage to generate heat. When the temperature of fuel cell stack 3 rises to its operating temperature, valves 7 and 9 are opened. The unreacted hydrogen in fuel cell stack 3 is introduced into reactor 1 to react with the oxidized metal catalyst to generate a reduced metal catalyst. After the reaction is complete, valves 4, 7, 8, and 9 are closed. During the process of introducing air and hydrogen into the fuel cell stack 3, valve 4 can be opened to allow the gas to enter the fuel cell stack 3 along with the air, or valve 4 can be closed and valve 9 opened to release the exhaust gas into the environment.

[0051] If the reduced metal catalyst in reactor 1 is completely converted to the oxidized metal catalyst, and the temperature of fuel cell stack 3 has not risen above 0°C, the following three methods can be used to further increase the temperature of fuel cell stack 3:

[0052] Method 1: The power battery 2 continues to heat the fuel cell stack 3 to above 0°C through electric heating. Then, air and hydrogen are introduced into the fuel cell stack 3, and the stack 3 is discharged under constant current or constant voltage to generate heat, so that the temperature of the fuel cell stack 3 rises to its operating temperature.

[0053] Method two: directly introduce air and hydrogen into the fuel cell stack 3, and discharge at constant current or constant voltage to make the stack 3 produce heat, so that the temperature of the fuel cell stack 3 rises to its working temperature.

[0054] Method three: the power battery 2 continues to heat the fuel cell stack 3 by electric heating, while air and hydrogen are introduced into the fuel cell stack 3, and the stack is discharged at constant current or constant voltage to make the stack produce heat, so that the temperature of the stack 3 rises to its working temperature. By combining chemical chain combustion heating, electric heating and stack self-heating, the fuel cell system is quickly heated, and the cold start method of combining multiple heat sources is fully utilized to solve the problems of high energy consumption and insufficient heating rate.

[0055] For Figure 2 As shown in the fuel cell system, the cold start method comprises: when the ambient temperature is between-50℃ and 0℃, open the first valve 8 and the third valve 4, and introduce air into the reactor 1 (the air can be supplied by an air bottle or a battery-driven air pump), the air reacts with the reduced metal catalyst in the reactor 1 to release heat, the released heat is used to heat the coolant in the coolant storage tank 10, the heated coolant is introduced into the coolant flow channel of the fuel cell stack 3 to heat the fuel cell stack 3, and the coolant in the coolant storage tank 10 is heated by heat pipe heat exchange and other methods to heat the power battery 2, and the tail gas of the reactor 1 enters the cathode flow channel of the fuel cell stack 3 to heat the stack. When the temperature of the fuel cell stack 3 is higher than 0℃, open the fourth valve 5 and the fifth valve 6, introduce air and hydrogen into the fuel cell stack 3, and discharge at constant current or constant voltage to make the fuel cell stack 3 produce heat. When the temperature of the fuel cell stack 3 rises to its working temperature, open the sixth valve 7 and the second valve 9, and the unreacted hydrogen in the fuel cell stack 3 is introduced into the reactor 1 to react with the oxidized metal catalyst to generate the reduced metal catalyst, and after the reaction is completed, the valves 4, 7, 8 and 9 are closed. During the process of introducing air and hydrogen into the fuel cell stack 3, the third valve 4 can be opened to enter the fuel cell stack 3 together with the air, or the third valve 4 can be closed and the second valve 9 can be opened to discharge the tail gas to the environment.

[0056] This method heats the fuel cell stack and the power battery by the heat released by the chemical chain combustion in the reactor, solves the limitations of existing cold start technologies which rely on external electric heating or stack self-heating, and can realize fast cold start of the fuel cell system.

[0057] When the reduced metal catalyst in the reactor 1 is completely converted into oxidized metal catalyst, and the temperature of the fuel cell stack 3 does not rise above 0℃, the temperature of the fuel cell stack 3 can be further raised by the following three methods:

[0058] The first way is that the power battery 2 continues to heat the fuel cell stack 3 to above 0°C by electric heating, then air and hydrogen are introduced into the fuel cell stack 3, and the fuel cell stack 3 is discharged at a constant current or a constant voltage to generate heat, so that the temperature of the fuel cell stack 3 rises to its working temperature. The second way is that air and hydrogen are directly introduced into the fuel cell stack 3, and the fuel cell stack 3 is discharged at a constant current or a constant voltage to generate heat, so that the temperature of the fuel cell stack 3 rises to its working temperature. The third way is that the power battery 2 continues to heat the fuel cell stack 3 by electric heating, while air and hydrogen are introduced into the fuel cell stack 3, and the fuel cell stack 3 is discharged at a constant current or a constant voltage to generate heat, so that the temperature of the fuel cell stack 3 rises to its working temperature.

[0059] The air reacts with the reduced metal catalyst M in the reactor 1 to release heat. The reduced metal catalyst involved is a copper-based catalyst, preferably a copper-zinc-aluminum catalyst or a copper-aluminum catalyst. The copper-based catalyst has high reactivity and can react with air to release a large amount of heat at a low temperature of -50°C to 0°C in a chemical chain combustion reaction, and the chemical reaction involved is:

[0060] M + xO2→ MO y + heat release, 0 < x < 2, y = 2x.

[0061] The hydrogen gas at the outlet of the fuel cell stack 3 is introduced into the reactor 1 to react with the oxidized metal catalyst (MO y ) to generate a reduced metal catalyst, and the chemical reaction involved is:

[0062] MO y + H2→ M + zH2O + heat release, z = y.

[0063] The above description shows and describes several preferred embodiments of the present application, but as mentioned above, it should be understood that the present application is not limited to the forms disclosed herein, and should not be considered as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application described herein, by the above teaching or related technical or knowledge. Any modification and change made by those skilled in the art without departing from the spirit and scope of the present application shall be within the protection scope of the appended claims of the present application.

Claims

1. A method of cold starting a fuel cell system, characterized by, The fuel cell system comprises a power battery, a reactor and a fuel cell stack, wherein the inlet of the reactor is connected to external air, and the outlet is connected to the power battery and the fuel cell stack; the power battery is connected to the fuel cell stack; the method comprises: S1. At ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain oxidized metal catalyst and release heat, and the released heat is used to heat the power battery and the fuel cell stack, and the power battery heats the fuel cell stack by electric heating; S2. The tail gas generated by the reaction enters the fuel cell stack to heat it; S3. When the heating makes the temperature of the fuel cell stack higher than 0℃, air and hydrogen are introduced into the fuel cell stack, and the fuel cell stack is discharged under constant current or constant voltage to generate heat; S4. When the heat makes the temperature of the fuel cell stack continue to rise to its working temperature, the hydrogen of the fuel cell stack is introduced into the reactor to react with the oxidized metal catalyst to generate reduced metal catalyst, and the reaction is ended to realize the cold start of the fuel cell system.

2. The method of claim 1, wherein, A first valve is arranged on the inlet pipeline of the reactor to control the introduction of air, and two branch pipelines are arranged at the outlet, a second valve is arranged on the first branch pipeline to control the discharge of tail gas, and the second branch pipeline is connected to the fuel cell stack and is provided with a third valve.

3. The method of claim 1, wherein, The ambient temperature is -50℃ to room temperature.

4. The method of claim 2, wherein, The fuel cell stack comprises two inlets and two outlets, the first inlet is connected to the second branch pipeline, and a fourth valve is arranged on the pipeline connected to the inlet to introduce air; a fifth valve is arranged on the pipeline connected to the second inlet to introduce hydrogen; the first outlet is connected to the ambient atmosphere, and the second outlet is connected to the inlet pipeline of the reactor through a pipeline, and a sixth valve is arranged on the pipeline to control the introduction of hydrogen into the reactor.

5. The method of claim 1, wherein, The reduced metal catalyst is a copper-based catalyst, preferably a copper-zinc-aluminum catalyst or a copper-aluminum catalyst.

6. The method of claim 3, wherein, When the reduced metal catalyst in the reactor is completely converted into oxidized metal catalyst, and the temperature of the fuel cell stack is not raised above 0℃, the temperature of the fuel cell stack is raised by the following three methods: Method one: the power battery continues to heat the fuel cell stack by electric heating to above 0℃, and then air and hydrogen are introduced into the fuel cell stack through the two inlets, and the fuel cell stack generates heat under constant current or constant voltage to raise the temperature of the fuel cell stack to its working temperature; Method two: air and hydrogen are directly introduced into the fuel cell stack through the two inlets, and the fuel cell stack generates heat under constant current or constant voltage to raise the temperature of the fuel cell stack to its working temperature; Method three: the power battery continues to heat the fuel cell stack by electric heating, and air and hydrogen are introduced into the fuel cell stack, and the fuel cell stack generates heat under constant current or constant voltage to raise the temperature of the fuel cell stack to its working temperature.

7. The method of claim 1, wherein, The fuel cell system further comprises a cooling liquid storage tank, which is connected to the reactor, the power battery and the fuel cell stack.

8. The method of claim 7, wherein, The S1 is specifically: at ambient temperature, the air introduced into the reactor reacts with the reduced metal catalyst therein to obtain the oxidized metal catalyst and releases heat, the released heat is used to heat the cooling liquid in the cooling liquid storage tank, the heated cooling liquid is introduced into the fuel cell stack to heat the fuel cell stack and the power battery, and the tail gas of the reactor is introduced into the fuel cell stack to heat the stack.

9. The method of claim 8, wherein, The S4 includes: when the reduced metal catalyst in the reactor is completely converted into the oxidized metal catalyst and the temperature of the fuel cell stack is not increased to above 0℃, the continuous heating of the fuel cell stack is realized by the following three ways: The first way: the power battery continues to heat the fuel cell stack to above 0℃ by electric heating, and then the fuel cell stack is introduced into air and hydrogen through the fourth valve and the fifth valve, and is discharged under constant current or constant voltage to generate heat in the stack, so that the temperature of the fuel cell stack is increased to the working temperature thereof; The second way: the fuel cell stack is directly introduced into air and hydrogen through the fourth valve and the fifth valve, and is discharged under constant current or constant voltage to generate heat in the stack, so that the temperature of the fuel cell stack is increased to the working temperature thereof; The third way: the power battery continues to heat the fuel cell stack by electric heating, and at the same time, the fuel cell stack is introduced into air and hydrogen through the fourth valve and the fifth valve, and is discharged under constant current or constant voltage to generate heat in the stack, so that the temperature of the fuel cell stack is increased to the working temperature thereof.

10. The method of claim 4, wherein, In the process of introducing air and hydrogen into the fuel cell stack, the third valve is opened to be introduced into the fuel cell stack together with the air, or the third valve is closed and the second valve is opened to discharge the tail gas to the environment.

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