Fuel cell system

Abstract

The present invention provides a fuel cell system, including a stack, a hydrogen oxidation heater, a hydrogen storage tank, a gas-water separator, a hydrogen circulation pump, an air filter, an air compressor, an intercooler, an air humidifier, a coolant circulation pump, a thermostat, and a radiator. The fuel cell system of the present invention is provided with a hydrogen oxidation heater, and the heat generated by the oxidation reaction of hydrogen and air is used to heat the coolant, so that the cold start of the fuel cell system can be achieved in a relatively short time; at the same time, the nitrogen remaining in the air after the combustion reaction is used to fill the anode flow channel, so as to avoid the hydrogen-air interface in the stack during the start-up and shutdown process, thereby improving the life of the fuel cell stack.

Description

Technical Field

[0001] The present invention relates to the technical field of fuel cells, and in particular to a fuel cell system. Background Art

[0002] In recent years, fuel cells have been widely recognized as a highly efficient and clean power generation technology for vehicle and ship power systems. When the proton exchange membrane fuel cell system used as a vehicle power source is used in the northern winter environment, the low-temperature start-up problem must be solved, otherwise the water generated by the fuel cell power generation will condense into water inside the stack, blocking the gas flow path and causing start-up failure.

[0003] At present, there are two main technical paths for low-temperature start of fuel cell systems. One is to add a cold start heater to the coolant circulation system. During cold start, the cold start heater is powered by an external battery, and the coolant circulation pump is started at the same time. The coolant is raised through the heater, and the temperature of the stack is raised to a certain extent through the coolant to ensure that the water generated by the stack will not freeze into ice again. Hydrogen and air are then introduced to smoothly start the fuel cell system. This method is widely used in actual systems, but the disadvantage is that the electric heating power is limited, usually only a few kilowatts, resulting in a long start-up heating time, usually more than ten minutes of start-up heating time, and even longer in cold areas. The coolant heating time can be shortened by increasing the power of the start-up heater, but if the start-up heating time is to be shortened to less than one minute, the power of the start-up electric heater needs to be increased to tens of kilowatts, which is a major challenge to the design of the heater. At the same time, it increases the weight and volume of the system and reduces the energy density of the fuel cell system.

[0004] Another fuel cell low-temperature start technology is to make the fuel cell stack operate at a lower voltage during the start-up process. At this time, most of the energy of hydrogen is converted into heat energy, which can raise the temperature of the stack to the operating temperature in a relatively short time. This low-temperature start technology is simple in system architecture and does not require the addition of other components, but its control process is very complicated. Directly pulling the stack voltage to a very low value at low temperature can easily cause partial polarization of the single cells inside the stack, and also easily cause local polarization in the single cell. Therefore, this direct low-temperature start method may have a certain impact on the working life of the stack.

[0005] For commercial vehicles, cold start can be performed by electric heating, and a slightly longer start time will not cause much trouble to users. However, for passenger cars, users often do not have enough patience to wait for ten minutes before starting the vehicle, and the long start time directly affects the market response of fuel cell vehicles. Fuel cell passenger cars need to complete cold start within 20 to 30 seconds, which is a big test for fuel cell cold start technology.

[0006] In addition, after the fuel cell system has been shut down for a long time, the cathode and anode flow fields inside the stack are filled with air. When starting, hydrogen is introduced into the anode. In the process of hydrogen blowing the air out of the stack, a hydrogen-oxygen interface is formed at the anode, which will cause a high potential on the cathode side, causing corrosion of the catalyst carbon carrier, thereby shortening the service life of the fuel cell stack. When the fuel cell system is bench tested in the laboratory, the hydrogen-air interface is often avoided by purging the anode with nitrogen, but in the actual application of the fuel cell system, it is impossible to add a nitrogen system. In the fuel cell system, the corrosion caused by the hydrogen-air interface can be avoided by closing the cathode air inlet and exhaust ports of the stack, consuming the oxygen in the cathode air, and leaving only nitrogen in the cathode flow channel, but this will increase the difficulty of cathode control.

[0007] In summary, the defects of the existing fuel cell cold start technology have not yet been effectively solved. Summary of the invention

[0008] The embodiments of the present invention are intended to provide a fuel cell system to solve the above-mentioned technical problems, thereby being able to achieve a cold start of the system in a shorter time and to increase the life of the fuel cell stack.

[0009] In order to solve the above technical problems, an embodiment of the present invention provides a fuel cell system, including a fuel cell stack, a hydrogen oxidation heater, a hydrogen storage tank, a gas-water separator, a hydrogen circulation pump, an air filter, an air compressor, an intercooler, an air humidifier, a coolant circulation pump, a thermostat, and a radiator; the hydrogen oxidation heater has a coolant inlet, a coolant outlet, a hydrogen inlet, a hydrogen outlet, and an air inlet;

[0010] The coolant outlet of the stack is connected to the inlet of the coolant circulation pump, the outlet of the coolant circulation pump is connected to the inlet of the radiator, a branch in the connecting pipeline between the outlet of the coolant circulation pump and the inlet of the radiator is connected to the first inlet of the thermostat, the outlet of the radiator is connected to the second inlet of the thermostat, the outlet of the thermostat is connected to the coolant inlet of the hydrogen oxidation heater, and the coolant outlet of the hydrogen oxidation heater is connected to the coolant inlet of the stack;

[0011] The hydrogen storage tank is connected to the hydrogen inlet of the hydrogen oxidation heater through a hydrogen switch valve, the hydrogen outlet of the hydrogen oxidation heater is connected to the hydrogen inlet of the fuel cell, the hydrogen exhaust port of the fuel cell is connected to the inlet of the gas-water separator, the drain port of the gas-water separator is connected to a hydrogen tail exhaust valve, the exhaust port of the gas-water separator is connected to the inlet of the hydrogen circulation pump, and the outlet of the hydrogen circulation pump is connected to the connecting pipeline between the hydrogen outlet of the hydrogen oxidation heater and the hydrogen inlet of the fuel cell;

[0012] The outlet of the air filter is connected to the inlet of the air compressor, the outlet of the air compressor is connected to the inlet of the intercooler, the outlet of the intercooler is connected to the dry air inlet of the air humidifier, a branch in the connecting pipeline between the intercooler and the air humidifier is connected to the air inlet of the hydrogen oxidation heater through an air start-stop control valve, the dry air outlet of the air humidifier is connected to the air inlet of the fuel cell stack, the air exhaust port of the fuel cell stack is connected to the wet air inlet of the air humidifier, the wet air outlet of the air humidifier is connected to the tail exhaust pipe, and a branch of the pipeline connecting the air exhaust port of the fuel cell stack and the wet air inlet of the air humidifier is connected to the tail exhaust pipe through an air tail exhaust valve.

[0013] As a preferred solution, a hydrogen flow control valve is further connected between the hydrogen switch valve and the hydrogen oxidation heater.

[0014] As a preferred solution, the hydrogen oxidation heater is a jacketed tube structure, comprising a coolant outer jacket and a hydrogen oxidation combustion tube, wherein the hydrogen oxidation combustion tube is jacketed inside the coolant outer jacket.

[0015] As a preferred solution, an air intake valve is provided at one end of the air inlet of the hydrogen oxidation heater.

[0016] As a preferred solution, an igniter is provided in the hydrogen oxidation heater, and the igniter is configured to start ignition when hydrogen and air are introduced into the hydrogen oxidation heater.

[0017] As a preferred solution, the hydrogen oxidation combustion tube is filled with hydrogen catalytic oxidation material.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] The present invention provides a fuel cell system, including a stack, a hydrogen oxidation heater, a hydrogen storage tank, a gas-water separator, a hydrogen circulation pump, an air filter, an air compressor, an intercooler, an air humidifier, a coolant circulation pump, a thermostat, and a radiator. The fuel cell system of the present invention is provided with a hydrogen oxidation heater, and the heat generated by the oxidation reaction of hydrogen and air is used to heat the coolant, so that the cold start of the fuel cell system can be achieved in a relatively short time; at the same time, the nitrogen remaining in the air after the combustion reaction is used to fill the anode flow channel, so as to avoid the hydrogen-air interface in the stack during the start-up and shutdown process, thereby improving the life of the fuel cell stack. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of a fuel cell system provided by one embodiment of the present invention;

[0021] Figure 2 is a schematic structural diagram of a hydrogen oxidation heater provided by one embodiment of the present invention;

[0022] The accompanying drawings are described as follows:

[0023] 11-hydrogen storage tank, 12-hydrogen switch valve, 13-hydrogen flow control valve, 14-hydrogen circulation pump, 15-gas-water separator, 16-hydrogen tail exhaust valve;

[0024] 21-air filter, 22-air compressor, 23-intercooler, 24-air start-stop control valve, 25-air humidifier; 26-air tail exhaust valve;

[0025] 31-coolant circulation pump, 32-radiator, 33-thermostat;

[0026] 50-hydrogen oxidation heater;

[0027] 100-battery stack. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] See also Figure 1 to Figure 2 The embodiment of the present invention provides a fuel cell system, including a fuel cell stack 100, a hydrogen oxidation heater 50, a hydrogen storage tank 11, a gas-water separator 15, a hydrogen circulation pump 14, an air filter 21, an air compressor 22, an intercooler 23, an air humidifier 25, a coolant circulation pump 31, a thermostat 33, and a radiator 32; the hydrogen oxidation heater has a coolant inlet, a coolant outlet, a hydrogen inlet, a hydrogen outlet, and an air inlet;

[0030] The coolant outlet of the battery stack 100 is connected to the inlet of the coolant circulation pump 31, and the outlet of the coolant circulation pump 31 is connected to the inlet of the radiator 32. A branch in the connecting pipeline between the outlet of the coolant circulation pump 31 and the inlet of the radiator 32 is connected to the first inlet of the thermostat 33, and the outlet of the radiator 32 is connected to the second inlet of the thermostat 33. The outlet of the thermostat 33 is connected to the coolant inlet of the hydrogen oxidation heater 50, and the coolant outlet of the hydrogen oxidation heater 50 is connected to the coolant inlet of the battery stack 100;

[0031] The hydrogen storage tank 11 is connected to the hydrogen inlet of the hydrogen oxidation heater 50 through a hydrogen switch valve 12, the hydrogen outlet of the hydrogen oxidation heater 50 is connected to the hydrogen inlet of the fuel cell stack 100, the hydrogen exhaust port of the fuel cell stack 100 is connected to the inlet of the gas-water separator 15, the drain port of the gas-water separator 15 is connected to a hydrogen tail exhaust valve 16, the exhaust port of the gas-water separator 15 is connected to the inlet of the hydrogen circulation pump 14, and the outlet of the hydrogen circulation pump 14 is connected to the connecting pipeline between the hydrogen outlet of the hydrogen oxidation heater 50 and the hydrogen inlet of the fuel cell stack 100;

[0032] The outlet of the air filter 21 is connected to the inlet of the air compressor 22, the outlet of the air compressor 22 is connected to the inlet of the intercooler 23, the outlet of the intercooler 23 is connected to the dry air inlet of the air humidifier 25, a branch is connected to the air inlet of the hydrogen oxidation heater 50 through an air start-stop control valve 24 in the connecting pipeline between the intercooler 23 and the air humidifier 25, the dry air outlet of the air humidifier 25 is connected to the air inlet of the fuel cell stack 100, the air exhaust port of the fuel cell stack 100 is connected to the wet air inlet of the air humidifier 25, the wet air outlet of the air humidifier 25 is connected to the tail exhaust pipe, and a branch is connected to the tail exhaust pipe through an air tail exhaust valve 26 in the pipeline connecting the air exhaust port of the fuel cell stack 100 and the wet air inlet of the air humidifier 25.

[0033] As a preferred solution, a hydrogen flow control valve 13 is further connected between the hydrogen switch valve 12 and the hydrogen oxidation heater 50 .

[0034] In an embodiment of the present invention, a hydrogen oxidation heater 50 is installed in the coolant circuit of the fuel cell system, and heat is provided to the coolant flowing through the hydrogen oxidation heater 50 through the hydrogen oxidation reaction, so as to realize the low-temperature start-up function of the fuel cell system; wherein, a hydrogen path in the hydrogen supply system is connected to the hydrogen oxidation heater 50 to provide it with hydrogen fuel; an air path in the air supply system is connected to the hydrogen oxidation heater 50 to provide it with an oxidant; the exhaust port of the hydrogen oxidation heater 50 is connected to the hydrogen inlet of the fuel cell stack 100, and the exhaust gas after the oxidation reaction of hydrogen and air provides a purge gas for the fuel cell stack 100 through the hydrogen inlet.

[0035] It should be noted that the fundamental difference between this system and the traditional fuel cell system is that the hydrogen oxidation heater 50 is used to heat the coolant circuit to achieve the low-temperature start function. The hydrogen oxidation heater 50 is connected in series in the main heat dissipation circuit of the fuel cell system. When starting at low temperature, the coolant circulation pump 31 is started, and the coolant flows in the small circulation circuit, flows out of the stack 100, passes through the coolant circulation pump 31, flows through the thermostat 33, and enters the hydrogen oxidation heater 50. After the coolant is heated by the hydrogen oxidation heater 50, the temperature rises and flows back to the stack 100, so that the temperature of the stack 100 gradually rises.

[0036] When the fuel cell system is started at low temperature, the coolant circulation pump 31 is started to circulate the coolant through the fuel cell stack 100; the air compressor 22 is started, and the air start-stop control valve 24 is opened to provide air for the hydrogen oxidation heater 50; at the same time, the hydrogen switch valve 12 and the hydrogen flow control valve 13 are opened to provide hydrogen for the hydrogen oxidation heater 50; hydrogen and air undergo a hydrogen oxidation reaction in the hydrogen oxidation heater 50, and the heat generated is used to heat the coolant flowing through the hydrogen oxidation heater 50, and the temperature of the fuel cell stack 100 is heated to above zero by the coolant with increased temperature flowing through the fuel cell stack 100; hydrogen and oxygen in the air react in the hydrogen oxidation heater 50, and the heat generated by the hydrogen oxidation reaction is used to heat the coolant flowing through the hydrogen oxidation heater 50. Water is generated by the reaction in the heater 50, and nitrogen remains in the exhaust gas. The nitrogen enters the anode flow channel of the fuel cell stack 100 through a pipe connecting the hydrogen oxidation heater 50 to the anode of the fuel cell stack 100, thereby realizing the anode flow channel purge, and avoiding the formation of a hydrogen-air interface at the anode of the fuel cell stack 100 during the startup process; when the coolant is heated to a certain degree, the air start-stop control valve 24 that supplies air to the hydrogen oxidation heater 50 is closed, and the hydrogen flows into the fuel cell stack 100 after passing through the hydrogen oxidation heater 50, gradually blowing the nitrogen out of the fuel cell stack 100, and the air enters the fuel cell stack 100 through the cathode pipeline, thereby building up a voltage for the fuel cell stack 100, realizing low-temperature startup and anode protective purge of the fuel cell system.

[0037] The hydrogen oxidation heater 50 is directly connected in series to the hydrogen supply circuit. When started, the hydrogen switch valve 12 is controlled to open, and hydrogen flows out from the hydrogen storage tank 11, passes through the hydrogen switch valve 12 and the hydrogen flow control valve 13 in sequence and enters the hydrogen oxidation heater 50. The hydrogen flow rate entering the hydrogen oxidation heater 50 is controlled by the hydrogen flow control valve 13, and the hydrogen reacts with the air in the hydrogen oxidation heater 50 to release heat to heat the coolant.

[0038] In the air circuit, after the air compressor 22 is started, the air passes through the air filter 21 and flows through the air compressor 22, and the temperature rises. After passing through the intercooler 23, the air is divided into two paths. One path enters the air humidifier 25 and then enters the fuel cell stack 100, and the other path passes through the air start-stop control valve 24 and enters the hydrogen oxidation heater 50 to react with the hydrogen to generate a combustion reaction. The oxygen in the air after the combustion reaction is consumed, and the remaining nitrogen enters the fuel cell stack 100. The hydrogen circulation pump 14 and the hydrogen tail exhaust valve 16 are started to blow all the air in the anode flow channel inside the fuel cell stack 100 out of the fuel cell stack 100, so that the inside of the anode is completely filled with nitrogen.

[0039] When the temperature of the fuel cell stack 100 rises to a certain level, the air start-stop control valve 24 is closed, and the hydrogen flows through the hydrogen oxidation heater 50 into the fuel cell stack 100, blowing the nitrogen in the anode flow field out of the stack 100, and the voltage of the stack 100 rises, and the startup process is completed. During the entire startup process, by controlling the flow of hydrogen and air entering the hydrogen oxidation heater 50, the coolant temperature can be quickly heated, and at the same time, the hydrogen-air interface in the anode is avoided, and the corrosion of the catalyst carbon carrier is avoided, thereby avoiding the shortening of the working life of the fuel cell stack 100.

[0040] When the fuel cell system is shut down, the air valve leading to the hydrogen oxidation heater 50 is gradually opened, so that the oxygen in the air reacts with the hydrogen in the hydrogen oxidation heater 50 to generate water, and the remaining nitrogen enters the anode flow channel of the fuel cell stack 100, and the hydrogen in the stack 100 and the pipeline is blown out of the fuel cell system, which is completely filled with nitrogen, and the valve is closed to achieve anode protection during the shutdown process.

[0041] During the shutdown process, the air start-stop control valve 24 is opened to introduce air into the hydrogen oxidation heater 50 to consume the hydrogen in the anode flow field. At the same time, the remaining nitrogen in the air purges the anode flow field, which can rapidly reduce the voltage of the stack 100. When the purge is completed, the hydrogen switch valve 12 and the hydrogen tail valve 16 are closed, so that the anode flow field of the stack 100 is only filled with nitrogen, and the stack 100 can be safely shut down to avoid the hydrogen-air interface.

[0042] As a preferred solution, the hydrogen oxidation heater 50 is a jacketed tube structure, and the hydrogen oxidation heater 50 includes a coolant outer jacket and a hydrogen oxidation combustion tube, and the hydrogen oxidation combustion tube is jacketed inside the coolant outer jacket.

[0043] As a preferred solution, an air intake valve is provided at one end of the air inlet of the hydrogen oxidation heater 50 .

[0044] As a preferred solution, an igniter is provided in the hydrogen oxidation heater 50 , and the igniter is configured to start ignition when hydrogen and air are introduced into the hydrogen oxidation heater 50 .

[0045] As a preferred solution, the hydrogen oxidation combustion tube is filled with hydrogen catalytic oxidation material.

[0046] In the embodiment of the present invention, the hydrogen oxidation heater 50 is installed in the main coolant circulation loop, the gas loop is connected in series to the main hydrogen supply loop, and in the air loop, a path of air is separated after passing through the intercooler 23 to enter the hydrogen oxidation heater 50. The hydrogen oxidation heater 50 is a jacketed tube structure, the hydrogen oxidation combustion tube is located inside, and the coolant flows through the outer sleeve, so that when the hydrogen is oxidized and burned in the tube, the heat can be fully transferred to the coolant flowing through the outer sleeve. The hydrogen oxidation heater 50 is integrated with an air start-stop control valve 24, and the air start-stop control valve 24 is opened only when the burner is working. The hydrogen oxidation heater 50 is integrated with an igniter. When hydrogen and air are introduced at low temperature, the igniter is started so that the hydrogen oxidation heater 50 can start working smoothly. The hydrogen oxidation heater 50 tube is filled with hydrogen catalytic oxidation material so that the hydrogen is fully oxidized and burned in the oxidation burner, and the heat generated by the combustion is quickly transferred to the coolant.

[0047] See also Figure 2 It should be noted that the hydrogen oxidation heater 50 in the embodiment of the present invention is a key component for realizing the function of the fuel cell system of the present invention. The hydrogen oxidation heater 50 is a jacketed tube structure, and the interior is a hydrogen oxidation combustion tube, which is the place where hydrogen and air undergo combustion reaction, and the coolant flows through the outer jacket. The heat generated inside the hydrogen oxidation combustion tube is transferred to the coolant through the pipeline, which plays a role in heating the coolant. The hydrogen oxidation heater 50 is integrated with an air intake valve to control whether air enters the reactor to participate in the oxidation reaction. Hydrogen enters the interior of the hydrogen oxidation combustion tube through the pipeline, and an igniter is also provided in the tube to realize the ignition of hydrogen at low temperature to produce an oxidation reaction. The interior of the hydrogen oxidation combustion tube is filled with a hydrogen oxidation catalyst, which can make the hydrogen entering the hydrogen oxidation combustion tube fully oxidized. At the same time, the heat generated by the oxidation can be effectively transferred to the reaction tube wall to realize the heating function of the coolant.

[0048] The above is a preferred embodiment of the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the principle of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A fuel cell system, characterized in that: It includes a fuel cell stack, a hydrogen oxidation heater, a hydrogen storage tank, a gas-water separator, a hydrogen circulation pump, an air filter, an air compressor, an intercooler, an air humidifier, a coolant circulation pump, a thermostat, and a radiator; the hydrogen oxidation heater has a coolant inlet, a coolant outlet, a hydrogen inlet, a hydrogen outlet, and an air inlet; The coolant outlet of the stack is connected to the inlet of the coolant circulation pump, the outlet of the coolant circulation pump is connected to the inlet of the radiator, a branch in the connecting pipeline between the outlet of the coolant circulation pump and the inlet of the radiator is connected to the first inlet of the thermostat, the outlet of the radiator is connected to the second inlet of the thermostat, the outlet of the thermostat is connected to the coolant inlet of the hydrogen oxidation heater, and the coolant outlet of the hydrogen oxidation heater is connected to the coolant inlet of the stack; The hydrogen storage tank is connected to the hydrogen inlet of the hydrogen oxidation heater through a hydrogen switch valve, the hydrogen outlet of the hydrogen oxidation heater is connected to the hydrogen inlet of the fuel cell, the hydrogen exhaust port of the fuel cell is connected to the inlet of the gas-water separator, the drain port of the gas-water separator is connected to a hydrogen tail valve, the exhaust port of the gas-water separator is connected to the inlet of the hydrogen circulation pump, the outlet of the hydrogen circulation pump is connected to the connecting pipeline between the hydrogen outlet of the hydrogen oxidation heater and the hydrogen inlet of the fuel cell, and a hydrogen flow control valve is also connected between the hydrogen switch valve and the hydrogen oxidation heater; The outlet of the air filter is connected to the inlet of the air compressor, the outlet of the air compressor is connected to the inlet of the intercooler, the outlet of the intercooler is connected to the dry air inlet of the air humidifier, a branch in the connecting pipeline between the intercooler and the air humidifier is connected to the air inlet of the hydrogen oxidation heater through an air start-stop control valve, the dry air outlet of the air humidifier is connected to the air inlet of the battery stack, the air exhaust port of the battery stack is connected to the wet air inlet of the air humidifier, the wet air outlet of the air humidifier is connected to the tail exhaust pipe, and a branch of the pipeline connecting the air exhaust port of the battery stack and the wet air inlet of the air humidifier is connected to the tail exhaust pipe through an air tail exhaust valve; The hydrogen oxidation heater is a jacketed tube structure, comprising a coolant outer jacket and a hydrogen oxidation combustion tube, wherein the hydrogen oxidation combustion tube is jacketed inside the coolant outer jacket.

2. The fuel cell system according to claim 1, characterized in that: An air inlet valve is arranged at one end of the air inlet of the hydrogen oxidation heater.

3. The fuel cell system according to claim 1, characterized in that: An igniter is provided in the hydrogen oxidation heater, and the igniter is configured to start ignition when hydrogen and air are introduced into the hydrogen oxidation heater.

4. The fuel cell system according to claim 1, characterized in that: The hydrogen oxidation combustion tube is filled with hydrogen catalytic oxidation material.

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