A wtp bipolar plate hydrogen-oxygen fuel cell system and a starting method thereof

Abstract

The application discloses a WTP bipolar plate hydrogen-oxygen fuel cell system and a starting method thereof. The system comprises a fuel cell stack; hydrogen and oxygen side gas inlet pipelines of the fuel cell stack are provided with hydrogen and oxygen side gas inlet electromagnetic valves, hydrogen and oxygen side gas outlet pipelines are provided with hydrogen and oxygen side gas outlet electromagnetic valves and pressure sensors; a cooling water outlet of the fuel cell stack is connected with a water inlet of a water tank through a first two-position three-way electromagnetic valve, an outlet pipeline of the water tank is sequentially provided with an internal circulation cooling water pump and a flow regulating valve, and a cooling water inlet of the fuel cell stack is connected with the outlet pipeline through a second two-position three-way electromagnetic valve. The application can make the fuel cell system not be limited to that the internal circulation cooling water tank is placed at the lowest end of the fuel cell stack and the fuel cell system, and can fully utilize the system space to place the internal circulation cooling water tank at any position without causing the cooling water in the internal circulation cooling water tank to flow back into the fuel cell.

Description

Technical Field

[0001] This invention relates to the field of fuel cell technology, and more specifically, to a WTP bipolar plate hydrogen-oxygen fuel cell system and its start-up method. Background Technology

[0002] A proton exchange membrane fuel cell (PEMFC) is a power generation device that directly and efficiently converts the chemical energy of fuel and oxidant into electrical energy. Due to its significant advantages such as high energy conversion efficiency, environmental friendliness, fast start-up speed, and low environmental pollution, PEMFC is considered one of the preferred power sources for electric vehicles, stationary power stations, and various mobile power sources. The bipolar plate is a crucial component in the PEMFC stack, performing functions such as fluid distribution, conductivity, cooling, and separation of fuel and oxidant. A common bipolar plate (traditional bipolar plate) has three chambers: a fuel chamber, an oxidant chamber, and a coolant chamber, which are kept separate, and fluids do not flow between them. Electrochemically generated water in the fuel cell stack enters the oxidant chamber and is then directly carried out of the cell by the gas flow or by gravity.

[0003] In recent years, a new type of permeable bipolar plate, namely the WTP bipolar plate (CN 1179428C, CN101501909A), has emerged. Its fuel chamber and oxidant chamber are separated, but a permeable plate (or "porous water transport plate") exists between the oxidant chamber and coolant chamber. In addition to the functions of traditional bipolar plates, this WTP plate also has a water-permeable and gas-blocking function. Water permeability and gas blocking means that during fuel cell operation, the generated water in the oxidant chamber can directly pass through the permeable plate of the bipolar plate into the coolant chamber due to the pressure difference between the oxidant and coolant chambers, and then be discharged from the fuel cell stack with the coolant. Simultaneously, the gas in the oxidant chamber will not pass through the permeable plate into the coolant chamber. This unique water-permeable and gas-blocking function of the permeable bipolar plate greatly reduces the gas flow rate requirements in the oxidant chamber, improves the battery's water management capability, and ensures high oxidant utilization.

[0004] Due to the permeability of the permeable plate, even when there is no pressure in the oxidant chamber, cooling water from the internal circulating cooling water tank and the coolant chamber will seep into the oxidant chamber under gravity, causing flooding of the battery and affecting its performance. This necessitates that the internal circulating cooling water tank of the WTP bipolar plate hydrogen-oxygen fuel cell stack be located at the bottom of the entire fuel cell stack to prevent cooling water from flowing back into the battery under gravity and then permeating into the oxidant chamber through the permeable plate. This fixed tank arrangement prevents the effective utilization of space within the WTP bipolar plate hydrogen-oxygen fuel cell system. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the present invention provides a WTP bipolar plate hydrogen-oxygen fuel cell system and its start-up method. Applying the present invention allows the battery system to no longer be limited to placing the internal circulating cooling water tank at the lowest end of the stack and battery system. It allows full utilization of system space, enabling the internal circulating water tank to be placed in any location without causing cooling water from the internal circulating water tank to backflow into the battery.

[0006] The technical means employed in this invention are as follows:

[0007] A WTP bipolar plate hydrogen-oxygen fuel cell system includes: a fuel cell stack;

[0008] The fuel cell stack is equipped with a hydrogen-side intake solenoid valve on the hydrogen-side intake pipe and a hydrogen-side exhaust solenoid valve on the hydrogen-side exhaust pipe. A hydrogen-side pressure sensor is installed between the hydrogen-side exhaust solenoid valve and the hydrogen-side exhaust port.

[0009] An oxygen-side intake solenoid valve is installed on the oxygen-side intake pipe of the fuel cell stack, and an oxygen-side exhaust solenoid valve is installed on the oxygen-side exhaust pipe. An oxygen-side pressure sensor is installed between the oxygen-side exhaust solenoid valve and the oxygen-side exhaust port.

[0010] The cooling water outlet of the fuel cell stack is connected to the water inlet of the water tank through a first two-position three-way solenoid valve. An internal circulation cooling water pump and a flow regulating valve are sequentially installed on the water outlet pipe of the water tank, and the cooling water inlet of the fuel cell stack is connected through a second two-position three-way solenoid valve.

[0011] This invention also discloses a start-up method for a WTP bipolar plate hydrogen-oxygen fuel cell system as described above, comprising the following steps:

[0012] Execute a pre-start procedure, which includes repeating the pre-start action N times. The pre-start action includes opening the intake solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack for pulse air intake, and simultaneously opening the exhaust solenoid valves at the hydrogen and oxygen outlets of the fuel cell stack.

[0013] The startup procedure is executed, which includes the exhaust solenoid valves at the hydrogen and oxygen outlets of the fuel cell stack being closed, the intake solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack using a pulse method to introduce gas into the hydrogen and oxygen chambers of the fuel cell stack, and simultaneously monitoring the internal pressure of the two chambers of the fuel cell stack at the hydrogen and oxygen outlets of the fuel cell stack.

[0014] When the internal pressure of the hydrogen and oxygen chamber of the fuel cell stack reaches the first pressure value preset by the fuel cell stack, the cooling water circulation pump of the battery system is turned on and the pump flow rate is maintained at the first preset flow rate. At the same time, the two electric two-position three-way valves at the fuel cell stack cooling water inlet and outlet start to switch the valve opening direction until the fuel cell stack cooling water inlet is connected to the cooling water circulation pump and the fuel cell stack cooling water outlet is connected to the internal circulating cooling water tank.

[0015] The solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack use a pulse method to introduce air into the hydrogen and oxygen chambers of the fuel cell stack. At the same time, the internal pressure of the two chambers of the fuel cell stack at the hydrogen and oxygen outlets is monitored. When the internal pressure of the hydrogen and oxygen chambers of the fuel cell stack reaches the second pressure value preset by the program, the battery system is started. At this time, the flow rate of the internal circulating cooling water pump is adjusted to the second preset flow rate, which is greater than the first preset flow rate.

[0016] Furthermore, the pre-start procedure and the start procedure maintain an initial state for 2 seconds; the initial state is that the hydrogen and oxygen inlet solenoid valves and the exhaust solenoid valve of the fuel cell stack are all in the closed state.

[0017] Furthermore, the duration of each pre-start procedure is 20–30 seconds.

[0018] Furthermore, in the aforementioned pre-start procedure, the opening time of the solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack is 200–300 ms, and the closing time is 1–2 s.

[0019] Furthermore, in the startup procedure, the solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack are opened and closed in a pulse manner. At the same time, the pressure sensors at the hydrogen and oxygen outlets monitor the pressure inside the hydrogen and oxygen chambers of the fuel cell stack to determine whether the hydrogen-side solenoid valve or the oxygen-side solenoid valve at the inlet is open.

[0020] Furthermore, in the aforementioned startup procedure, the solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack open for 200–300 ms each time and close for 1–2 s.

[0021] Furthermore, in the aforementioned startup procedure, the preset first pressure value is 0.4 to 0.5 bar, and the preset second pressure value is 0.7 bar.

[0022] Furthermore, in the aforementioned startup procedure, the switching time of the electric two-position three-way valve from switching the valve opening direction does not exceed 8 seconds.

[0023] Compared with the prior art, the present invention has the following advantages:

[0024] 1. This startup method is mainly for WTP bipolar plate hydrogen-oxygen fuel cell systems. This battery system is no longer limited to placing the internal circulating cooling water tank at the lowest end of the stack and battery system. It can make full use of the system space and place the internal circulating water tank of the battery system in any position without causing the cooling water in the internal circulating water tank to flow back into the battery.

[0025] 2. Before the WTP bipolar plate fuel cell stack is started, the present invention controls the opening direction of the electric two-position three-way valve to keep the coolant chamber of the stack disconnected from the internal circulating cooling water tank of the battery system, thereby ensuring that the coolant chamber of the battery remains dry.

[0026] 3. During the shutdown process of the WTP bipolar plate fuel cell system, the present invention switches the opening direction of the electric two-position three-way valve to disconnect the coolant chamber of the fuel cell stack from the internal circulating cooling water tank, while keeping the coolant chamber of the fuel cell stack connected to the atmosphere. Through the siphon effect of the cooling water, the cooling water in the coolant chamber can be effectively and quickly discharged, preventing the liquid water remaining inside the battery from seeping into the oxidant chamber through the WTP bipolar plate and causing electrode contamination.

[0027] 4. During startup, this invention effectively prevents the internal circulating cooling water from seeping into the oxidant chamber through the WTP bipolar plate and causing battery flooding by controlling the flow rate of the internal circulating cooling water pump and controlling the switching timing of the two-position three-way valve. It also prevents the pump from becoming blocked and unable to operate normally due to obstruction in the pipeline between the coolant chamber and the internal circulating water pump. Attached Figure Description

[0028] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0029] Figure 1 This is a structural block diagram of a WTP bipolar plate hydrogen-oxygen fuel cell system according to the present invention.

[0030] In the diagram: 1. Hydrogen-side inlet; 2. Oxygen-side inlet; 3. Hydrogen-side exhaust port; 4. Oxygen-side exhaust port; 5. Cooling water outlet; 6. Cooling water inlet; 7. Hydrogen-side inlet solenoid valve; 8. Oxygen-side inlet solenoid valve; 9. Hydrogen-side exhaust solenoid valve; 10. Oxygen-side exhaust solenoid valve; 11. Hydrogen-side pressure sensor; 12. Oxygen-side pressure sensor; 13. Internal circulating cooling water pump; 14. Flow regulating valve; 15. Internal circulating cooling water tank; 16. First electric two-position three-way valve; 17. Second electric two-position three-way valve. Detailed Implementation

[0031] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0032] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0033] Example 1

[0034] The fuel cell system of this application includes: a circulating water pump 13 with a flow regulating valve 14, the circulating water pump 13 being connected to an internal circulating cooling water tank 15, the outlet of the circulating water pump 13 being connected to the stack cooling water inlet 6, an electric two-position three-way valve 17 being installed between the circulating water pump and the stack cooling water inlet, the stack cooling water outlet 5 being connected to the internal circulating water tank 15, and an electric two-position three-way valve 16 being installed between the stack cooling water outlet and the internal circulating water tank; an intake solenoid valve 7 and an exhaust solenoid valve 8 are respectively installed at the hydrogen and oxygen inlets 1 and 2 of the stack, and an exhaust solenoid valve 9 and an exhaust solenoid valve 10 are respectively installed at the hydrogen and oxygen outlets 3 and 4 of the stack, and a pressure sensor 11 and a pressure sensor 12 are respectively installed between each exhaust solenoid valve and the outlet.

[0035] To successfully start a 50-cell WTP bipolar plate hydrogen-oxygen fuel cell stack on a battery system, the internal circulating cooling water tank of the battery system must be placed at the top of the battery system, above the fuel cell stack, due to space constraints. The battery system startup procedure requires both the hydrogen and oxygen chamber pressures to reach 0.7 bar as a condition for successful startup. Before the battery system enters the startup procedure, the electrically operated two-position three-way valve 17 at the cooling water inlet is in the connected state between B and C, and the electrically operated two-position three-way valve 16 at the cooling water outlet is in the connected state between D and F. When the battery system enters the startup procedure, the startup procedure includes three pre-start procedures, each lasting 30 seconds. During the pre-start process, the hydrogen-side inlet solenoid valve 7 and the oxygen-side inlet solenoid valve 8 at the hydrogen and oxygen inlets of the battery stack are opened in a pulse manner, with an opening time of 200 ms and a closing time of 2 seconds. The hydrogen-side exhaust solenoid valve 9 and the oxygen-side exhaust solenoid valve 10 at the hydrogen and oxygen outlets of the battery stack are opened, allowing the gas to flow. At this time, the voltage of each cell in the battery stack begins to rise. After one pre-start, the initial state is maintained for 2 seconds. The initial state is: the hydrogen-side inlet solenoid valve 7 and the oxygen-side inlet solenoid valve 8 are closed, and the hydrogen-side exhaust solenoid valve 9 and the oxygen-side exhaust solenoid valve 10 at the hydrogen and oxygen outlets are closed. After the three pre-starts, the voltage of each cell basically reaches above 0.90V. After three pre-starts, the initial state is maintained for 2 seconds, and the fuel cell stack enters the startup procedure. During the startup procedure, the hydrogen-side inlet solenoid valve 7 and the oxygen-side inlet solenoid valve 8 at the fuel cell stack inlet open and close simultaneously in a pulse manner. The valve opening time is 200ms and the valve closing time is 2s. The hydrogen-side exhaust valve 9 and the oxygen-side exhaust valve 10 are in the closed state. The internal pressure of the fuel cell stack is measured by the hydrogen-side pressure sensor 11 and the oxygen-side pressure sensor 12 at the fuel cell stack outlet. After the hydrogen and oxygen-side inlet solenoid valves 7 and 8 complete two pulse intakes, the pressures on the hydrogen and oxygen sides are compared. The solenoid valve on the side with higher pressure closes, and the solenoid valve on the side with lower pressure continues to pulse intake. When the hydrogen and oxygen-side pressures reach 0.5 bar, the circulating water pump 13 starts running, and the flow rate is maintained at 8-10 L / min. At the same time, the electric two-position three-way valve 16 at the cooling water outlet and the electric two-position three-way valve 17 at the cooling water inlet start switching the valve opening direction until the A and B and D and DE are connected. Solenoid valves 7 and 8 at the hydrogen and oxygen inlets continue to pulse air intake in the manner described above, while simultaneously monitoring the pressure inside the hydrogen and oxygen chambers of the fuel cell stack until the pressure inside the hydrogen and oxygen chambers reaches 0.7 bar, at which point the flow rate of the circulating water pump increases to 40–45 L / min.

[0036] Example 2

[0037] After a 50-cell WTP bipolar plate hydrogen-oxygen fuel cell stack completes power generation, it is about to be shut down. At this time, the electrically operated two-position three-way valve 17 at the cooling water inlet of the stack is in the A / B connected state, and the electrically operated two-position three-way valve 16 at the cooling water outlet of the stack is in the D / E connected state. The cooling water circulation pump 13 is running, with a flow rate of 40-45 L / min. When the battery system enters shutdown mode, the cooling water circulation pump 13 is turned off. At the same time, the electrically operated two-position three-way valve 17 at the cooling water inlet of the stack starts to switch from the A / B connected state to the B / C connected state, and the electrically operated two-position three-way valve 16 at the cooling water inlet starts to switch from the D / E connected state to the DF connected state. At this time, the cooling water in the stack coolant chamber is discharged through the two-position three-way valves until it is empty. The solenoid valves 7 and 8 at the hydrogen and oxygen side inlets of the stack both change from the open state to the closed state. At the same time, the solenoid valves 9 and 10 at the hydrogen side outlet of the stack also change from the open state to the closed state. The valve opens and closes in a pulse manner, with an opening time of 200ms and a closing time of 2s. The internal pressure of the fuel cell stack is measured by the hydrogen-side pressure sensor 11 and the oxygen-side pressure sensor 12 at the fuel cell stack outlet. After the exhaust solenoid valves 9 and 10 at the hydrogen and oxygen-side outlets complete two pulse exhausts, the pressures on the hydrogen and oxygen sides are compared. The exhaust solenoid valve on the side with higher pressure continues to open pulse, while the exhaust solenoid valve on the side with lower pressure closes. When the internal pressure of the hydrogen and oxygen chamber reaches 0.2 bar, the exhaust solenoid valves 9 and 10 at the hydrogen and oxygen-side outlets open simultaneously until the internal pressure drops to 0, and the shutdown procedure is completed.

[0038] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A start-up method for a WTP bipolar plate hydrogen-oxygen fuel cell system, characterized in that, The WTP bipolar plate hydrogen-oxygen fuel cell system includes: a fuel cell stack; The fuel cell stack is equipped with a hydrogen-side intake solenoid valve on the hydrogen-side intake pipe and a hydrogen-side exhaust solenoid valve on the hydrogen-side exhaust pipe. A hydrogen-side pressure sensor is installed between the hydrogen-side exhaust solenoid valve and the hydrogen-side exhaust port. An oxygen-side intake solenoid valve is installed on the oxygen-side intake pipe of the fuel cell stack, and an oxygen-side exhaust solenoid valve is installed on the oxygen-side exhaust pipe. An oxygen-side pressure sensor is installed between the oxygen-side exhaust solenoid valve and the oxygen-side exhaust port. The cooling water outlet of the fuel cell stack is connected to the water inlet of the water tank through a first two-position three-way solenoid valve. An internal circulation cooling water pump and a flow regulating valve are sequentially installed on the water outlet pipe of the water tank, and the cooling water inlet of the fuel cell stack is connected through a second two-position three-way solenoid valve. The startup method of the WTP bipolar plate hydrogen-oxygen fuel cell system includes the following steps: Execute a pre-start procedure, which includes repeating the pre-start action N times. The pre-start action includes opening the intake solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack for pulse air intake, and simultaneously opening the exhaust solenoid valves at the hydrogen and oxygen outlets of the fuel cell stack. The startup procedure is executed, which includes the exhaust solenoid valves at the hydrogen and oxygen outlets of the fuel cell stack being closed, the intake solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack using a pulse method to introduce air into the hydrogen and oxygen chambers of the fuel cell stack, and simultaneously monitoring the internal pressure of the two chambers of the fuel cell stack at the hydrogen and oxygen outlets of the fuel cell stack. When the internal pressure of the hydrogen and oxygen chamber of the fuel cell stack reaches the first pressure value preset by the fuel cell stack, the cooling water circulation pump of the battery system is turned on and the pump flow rate is maintained at the first preset flow rate. At the same time, the two electric two-position three-way valves at the fuel cell stack cooling water inlet and outlet start to switch the valve opening direction until the fuel cell stack cooling water inlet is connected to the cooling water circulation pump and the fuel cell stack cooling water outlet is connected to the internal circulating cooling water tank. The solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack use a pulse method to introduce air into the hydrogen and oxygen chambers of the fuel cell stack. At the same time, the internal pressure of the two chambers of the fuel cell stack at the hydrogen and oxygen outlets is monitored. When the internal pressure of the hydrogen and oxygen chambers of the fuel cell stack reaches the second pressure value preset by the program, the battery system is started. At this time, the flow rate of the internal circulating cooling water pump is adjusted to the second preset flow rate, which is greater than the first preset flow rate.

2. The start-up method of the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 1, characterized in that, The pre-start procedure and the start procedure maintain an initial state for 2 seconds; the initial state is that the hydrogen and oxygen inlet solenoid valves and the exhaust solenoid valve of the fuel cell stack are all in the closed state.

3. The start-up method for the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 1, characterized in that, Each pre-start procedure lasts for 20-30 seconds.

4. The start-up method of the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 1, characterized in that, In the aforementioned pre-start procedure, the opening time of the solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack is 200~300 ms, and the closing time is 1~2 s.

5. The start-up method of the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 1, characterized in that, In the startup procedure, the solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack are opened and closed in a pulse manner. At the same time, the pressure sensors at the hydrogen and oxygen outlets monitor the pressure inside the hydrogen and oxygen chambers of the fuel cell stack to determine whether the hydrogen-side solenoid valve or the oxygen-side solenoid valve at the inlet is open.

6. The start-up method of the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 5, characterized in that, In the aforementioned startup procedure, the solenoid valves at the hydrogen and oxygen inlets of the fuel cell stack open for 200-300 ms and close for 1-2 s each time.

7. The start-up method for the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 1, characterized in that, In the aforementioned startup procedure, the preset first pressure value is 0.4~0.5 bar, and the preset second pressure value is 0.7 bar.

8. The start-up method for the WTP bipolar plate hydrogen-oxygen fuel cell system according to claim 1, characterized in that, In the aforementioned startup procedure, the switching time of the electric two-position three-way valve from switching the valve opening direction shall not exceed 8 seconds.

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