A fuel cell hydrogen temperature and humidity control system and its control method

Abstract

The present invention discloses a fuel cell hydrogen temperature and humidity control system and its control method, belonging to the field of fuel cells. The present invention includes an electric stack, a hydrogen storage device, a hydrogen inlet pipeline, a hydrogen outlet pipeline, a coolant outlet pipeline, a hydrogen control valve and a heat exchange device. A hydrogen inlet, a hydrogen outlet and a coolant outlet are provided on the electric stack. The hydrogen inlet pipeline is connected from the hydrogen storage device to the hydrogen inlet, the hydrogen outlet pipeline is connected from the hydrogen outlet to the hydrogen inlet pipeline, the hydrogen control valve is arranged at the connection between the hydrogen inlet pipeline and the heat exchange device, the heat exchange device is arranged in the coolant outlet pipeline, and the hydrogen inlet pipeline is selectively communicated with the heat exchange device through the hydrogen control valve. The gas coming from the hydrogen storage device passes through the serpentine pipe section of the heat exchange device to perform efficient heat interaction, significantly improving the heat exchange efficiency, and without additionally increasing complex devices, saving space and weight in the actual application process of the engine and improving the system performance parameters.

Description

Technical Field

[0001] The present invention relates to the field of fuel cells, and more particularly to a fuel cell hydrogen temperature and humidity control system and a control method thereof. Background Art

[0002] With the development of hydrogen fuel cell technology, higher requirements are put forward for the hydrogen supply technology of fuel cell engines. Under the current technology, it is required that there is no liquid water in the whole process of hydrogen entering the fuel cell engine, and at the same time, a certain mixing humidity is required to achieve a better reaction effect. At present, the hydrogen inlet humidity control method mostly adjusts the hydrogen return flow. If the hydrogen inlet humidity is high, the return flow is appropriately reduced. If the hydrogen inlet humidity is low, the return flow is appropriately increased. This method is simple and crude and cannot achieve precise control. At the same time, the increase or decrease of the hydrogen metering ratio will also affect the performance of the fuel cell stack. Under winter conditions, the hydrogen coming out of the hydrogen cylinder is a low-temperature gas. When it is mixed with the humid and hot gas from the fuel cell hydrogen circulation path, condensate will be generated. Therefore, in order to avoid this problem, it is necessary to process the hydrogen supplied by the hydrogen cylinder, increase its temperature, and avoid the condensate entering the fuel cell stack and damaging the engine.

[0003] In the prior art, the patent CN112582642A has two devices, namely a heat preservation device and a heating device. The heat preservation unit is arranged between the coolant outlet pipe and the hydrogen outlet pipe, and uses the coolant in the coolant outlet pipe to keep the hydrogen in the hydrogen outlet pipe warm; the heating unit is arranged between the coolant outlet pipe and the hydrogen inlet pipe and uses the coolant in the coolant outlet pipe to heat the hydrogen in the hydrogen inlet pipe. The system uses the waste heat of the coolant to keep the hydrogen path warm and heated, reducing the additional components of the system and the additional power consumption of the system; moreover, the coolant flow can be adjusted through a three-way regulating valve, and then the temperature and humidity of the hydrogen entering the fuel cell stack can be controlled to meet the requirements of different fuel cell stacks and different working conditions for the temperature and humidity of the hydrogen entering. In the patent CN112713285A, a hydrogen heating and dehumidifying mechanism is arranged on one side of the fuel cell, and an oxygen heating and dehumidifying mechanism is arranged on the other side. A hydrogen pipe is arranged at the air inlet end of the hydrogen heating and dehumidifying mechanism, a hydrogen inlet pipe is arranged at the air outlet end of the heating and dehumidifying mechanism, a hydrogen return valve is arranged at the middle position of the hydrogen inlet pipe, a hydrogen return pipe is hermetically connected to one side of the hydrogen return valve, an oxygen pipe is arranged at the air inlet end of the oxygen heating and dehumidifying mechanism, an oxygen inlet pipe is arranged at the air outlet end of the oxygen heating and dehumidifying mechanism, and a heat absorption mechanism is arranged on one side below the hydrogen fuel cell. By jointly regulating the temperature and humidity, the purpose of meeting the standard of temperature and humidity is achieved. In the patent CN112713286A, the fuel cell system includes a stack, an anode gas mixture chamber and a coolant chamber. The heat exchange device includes a first heat exchange unit and a second heat exchange unit. The first heat exchange unit is located in the anode gas mixture chamber, and the second heat exchange unit is located in the coolant chamber. The second heat exchange unit can exchange heat with the high-temperature coolant coming out of the stack and transfer the heat to the first heat exchange unit. Then the first heat exchange unit can heat the hydrogen gas mixture before entering the stack. The temperature of the hydrogen gas mixture before entering the anode of the fuel cell approaches the appropriate temperature of the system, and at the same time, the risk of excessive condensation of liquid water in the anode hydrogen gas mixture entering the stack is avoided. And this solution has high energy utilization rate, does not require external heat source supply, optimizes the water and heat management method of the stack, the whole heat exchange device is integrated with the stack end plate, with a compact structure and high space utilization rate. In the patent CN211320222U, the circulating water inlet pipe is connected between the water outlet of the water pump and the coolant inlet of the stack; the circulating water outlet pipe is connected between the water return port of the water pump and the coolant outlet of the stack; the heat exchanger is arranged on the hydrogen inlet pipe in front of the stack, and the intercooler is arranged on the air inlet pipe in front of the stack and downstream of the air compressor in the air inlet pipe; the water outlet of the heat exchanger is communicated with the circulating water outlet pipe, and the water return port of the heat exchanger is communicated with the water outlet of the intercooler; the water return port of the intercooler is communicated with the circulating water inlet pipe. This hydrogen heating water circulation system avoids the problem that the ambient temperature of the hydrogen in front of the stack and the air entering the stack have a large temperature difference, which affects the reaction efficiency and has an adverse effect on the stack.

[0004] The following technical problems exist in the prior art:

[0005] In CN112582642A, the waste heat of the coolant is used to keep the gas warm and heated, but the efficiency is not high, and it can only control the temperature, which cannot meet the requirements of fuel cell operation. At the same time, for the regulation of the flow rate, the range is not large, and there is a great possibility of increasing the temperature at the outlet of the fuel cell, causing damage to the engine.

[0006] In CN112713285A, by arranging a large number of peripheral devices, such as heating and dehumidifying mechanisms, hydrogen reflux valves, heat absorption mechanisms and other devices, for a fuel cell engine, it increases the overall weight and volume, the cost is relatively high, and it is not convenient for the layout of the actual application scenario. Moreover, the increase in weight and volume will also reduce the performance parameters of the engine.

[0007] In CN112713286A, the heat exchange element is integrated with the stack end plate, which simplifies the structure. However, due to the layout of the structure, hydrogen is always in a heated state and the humidity cannot be regulated. It is a passive response structure. In summer or other high-temperature environments, it will cause the gas supplied by the hydrogen cylinder to converge with the hydrogen heated at high temperature, resulting in the situation of over-dry hydrogen.

[0008] In CN211320222U, the overall structure of the stack is rearranged, and the change in the heat circulation method has the effect of increasing the complexity of the system and reducing the stability of the system. Moreover, this invention cannot regulate the temperature, and it only has a heating effect and cannot meet the actual temperature and humidity regulation requirements. At the same time, the starting point of this invention is to avoid too large a temperature difference between hydrogen and air.

[0009] Therefore, it is urgent to provide a fuel cell hydrogen temperature and humidity regulation system and its regulation method to solve the above technical problems in the prior art. Summary of the Invention

[0010] The purpose of the present invention is to provide a fuel cell hydrogen temperature and humidity regulation system and its regulation method, which has higher heat exchange efficiency, can effectively increase the temperature of hydrogen, and avoid the generation of condensed water in winter.

[0011] To achieve the above purpose, the following technical solutions are provided:

[0012] The present invention provides a hydrogen temperature and humidity control system for a fuel cell, comprising: a fuel cell stack, a hydrogen storage device, a hydrogen inlet pipeline, a hydrogen outlet pipeline, a coolant outlet pipeline, a hydrogen control valve and a heat exchange device. The fuel cell stack is provided with a hydrogen inlet, a hydrogen outlet and a coolant outlet. The hydrogen inlet pipeline is connected from the hydrogen storage device to the hydrogen inlet. The hydrogen outlet pipeline is connected from the hydrogen outlet to the hydrogen inlet pipeline. The hydrogen control valve is arranged at the connection of the hydrogen inlet pipeline and the heat exchange device. The heat exchange device is arranged in the coolant outlet pipeline, and the hydrogen inlet pipeline is selectively communicated with the heat exchange device through the hydrogen control valve.

[0013] Further, the hydrogen control valve is a three-way valve.

[0014] Further, the hydrogen temperature and humidity control system for the fuel cell further comprises a water circulation outlet, which is arranged at the end of the coolant outlet pipeline.

[0015] Further, the heat exchange device comprises a serpentine pipe section arranged in the coolant outlet pipeline, and the hydrogen inlet pipeline is communicated with the serpentine pipe section.

[0016] Further, the heat exchange device further comprises a heat exchange hydrogen inlet and a heat exchange hydrogen outlet. The hydrogen control valve is arranged at the heat exchange hydrogen outlet, and the opening and closing of the hydrogen control valve are controlled to control whether hydrogen passes through the heat exchange device.

[0017] Further, the hydrogen control valve is arranged at the heat exchange hydrogen inlet, and the opening and closing of the hydrogen control valve are controlled to control whether hydrogen passes through the heat exchange device.

[0018] Further, the outer wall of the cooling water outlet pipeline is coated with a heating film.

[0019] Further, a heating element is arranged inside the pipe wall of the cooling water outlet pipeline.

[0020] The present invention also provides a method for controlling the hydrogen temperature and humidity of a fuel cell, comprising the following steps:

[0021] S100: Judge whether the current ambient temperature will cause condensed water to be generated. If so, enter S200; if not, enter S500;

[0022] S200: Close the hydrogen control valve, perform hydrogen preheating, and enter S300;

[0023] S300: Judge whether the content of condensed water entering the stack is higher than the standard. If so, enter S400; if not, enter S500;

[0024] S400: Increase the heating temperature;

[0025] S500: Determine whether the current ambient humidity reaches the standard. If so, proceed to S600; if not, proceed to S700.

[0026] S600: Maintain the opening degree of the hydrogen control valve and the current heating temperature.

[0027] S700: Adjust the hydrogen control valve to make the ambient humidity reach the standard.

[0028] Furthermore, S700 includes the following steps:

[0029] S710: Determine whether the current ambient humidity is too low. If so, proceed to S720; if not, proceed to S730.

[0030] S720: Reduce the opening degree of the hydrogen control valve and proceed to S500.

[0031] S730: Increase the opening degree of the hydrogen control valve and proceed to S500.

[0032] Compared with the prior art, the fuel cell hydrogen temperature and humidity control system provided by the present invention uses the high-temperature liquid at the outlet of the water circulation path of the fuel cell engine to heat hydrogen. This heat exchange structure is integrated with the water circulation pipeline through special design, and can ensure the design on the original system architecture as much as possible without increasing the external contour of the system and additional design. When the engine is working, the high-temperature liquid can heat the low-temperature gas coming out of the hydrogen cylinder, and the heating efficiency is high. Under summer conditions, the high-temperature gas coming out of the hydrogen cylinder will also be mixed with the high-temperature gas of hydrogen reflux, resulting in the gas being too dry. Therefore, the three-way valve can be closed to directly mix hydrogen and avoid secondary heating of hydrogen, resulting in hydrogen being too dry. During the humidity control process, the humidity is not controlled by adjusting the hydrogen return flow rate, which can effectively avoid the loss of accessory power consumption caused by the increase of the return flow rate, and also avoid the negative impact that the increase of the stoichiometric ratio may bring to the fuel cell stack, ensuring the working performance of the fuel cell stack. The present invention effectively adjusts the hydrogen inlet temperature and humidity through the cooperation of the hydrogen control valve and the heat exchange device by adjusting the opening degree of the hydrogen control valve under different ambient temperatures; there are no additional complex components, effectively reducing the weight and volume of the system and improving the system performance parameters; for the change of the environment, the water flow rate does not need to be adjusted to control the temperature and humidity, while ensuring the hydrogen inlet temperature and humidity, the fuel cell stack is protected. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic structural diagram of the fuel cell hydrogen temperature and humidity control system according to the embodiment of the present invention;

[0034] Figure 2Flow chart of the fuel cell hydrogen temperature and humidity control method according to the embodiment of the present invention.

[0035] Reference numerals:

[0036] 1 - Stack; 2 - Hydrogen inlet pipeline; 3 - Hydrogen outlet pipeline; 4 - Hydrogen circulation pipeline; 5 - Coolant outlet pipeline; 6 - Heat exchange device; 7 - Hydrogen storage device; 8 - Water circulation outlet; 9 - Hydrogen control valve. Detailed implementation manners

[0037] To make the technical problems solved by the present invention, the technical solutions adopted and the achieved technical effects clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative efforts belong to the scope of protection of the present invention.

[0038] This embodiment provides a fuel cell hydrogen temperature and humidity control system, including: a stack 1, a hydrogen storage device 7, a hydrogen inlet pipeline 2, a hydrogen outlet pipeline 3, a coolant outlet pipeline 5, a hydrogen control valve 9, and a heat exchange device 6. A hydrogen inlet, a hydrogen outlet, and a coolant outlet are provided on the stack 1. The hydrogen inlet pipeline 2 is connected from the hydrogen storage device 7 to the hydrogen inlet, the hydrogen outlet pipeline 3 is connected from the hydrogen outlet to the hydrogen inlet pipeline 2, the hydrogen control valve 9 is provided at the connection between the hydrogen inlet pipeline 2 and the heat exchange device 6, the heat exchange device 6 is provided in the coolant outlet pipeline 5, and the hydrogen inlet pipeline 2 is selectively communicated with the heat exchange device 6 through the hydrogen control valve 9.

[0039] Specifically, the hydrogen outlet pipeline 3 is communicated with the hydrogen inlet pipeline 2 through a hydrogen circulation pipeline 4.

[0040] Further, the fuel cell hydrogen temperature and humidity control system further includes a water circulation outlet 8, and the water circulation outlet 8 is provided at the end of the coolant outlet pipeline 5.

[0041] Optionally, the hydrogen control valve 9 is a three-way valve. Preferably, the heat exchange device 6 includes a serpentine pipe section provided in the coolant outlet pipeline 5, and the hydrogen inlet pipeline 2 is communicated with the serpentine pipe section. The gas coming from the hydrogen storage device 7 passes through the serpentine pipe section of the heat exchange device 6 for efficient heat interaction, the heat exchange efficiency is significantly improved, and no additional complex devices are added, saving space and weight in the actual application process of the engine and improving the system performance parameters. The opening and closing of the hydrogen control valve 9 control the flow direction of the gas, with a simple structure, high efficiency in use. Specifically, the heat exchange device 6 of this embodiment is made of a metal material with good thermal conductivity, preferably stainless steel, and it also has relatively good corrosion resistance.

[0042] Further, the heat exchange device 6 of this embodiment further includes a heat exchange hydrogen inlet and a heat exchange hydrogen outlet. The hydrogen control valve 9 is disposed at the heat exchange hydrogen outlet, and whether hydrogen passes through the heat exchange device 6 is controlled by controlling the opening and closing of the hydrogen control valve 9. In another embodiment, the hydrogen control valve 9 is disposed at the heat exchange hydrogen inlet, and whether hydrogen passes through the heat exchange device 6 is controlled by controlling the opening and closing of the hydrogen control valve 9.

[0043] Preferably, in order to keep the high-temperature coolant in the coolant outlet pipe 5 at a relatively high temperature, the outer wall of the cooling water outlet pipe of this embodiment is coated with a heating film. In another embodiment, a heating element, such as an electric heating wire, is disposed inside the wall of the cooling water outlet pipe.

[0044] This embodiment also provides a method for regulating the temperature and humidity of hydrogen in a fuel cell, including the following steps:

[0045] S100: Start;

[0046] S200: Determine whether the current ambient temperature will cause condensed water to be generated. If so, proceed to S300; if not, proceed to S600.

[0047] S300: Close the hydrogen control valve 9, perform hydrogen preheating, and proceed to S400.

[0048] S400: Determine whether the content of condensed water entering the stack is higher than the standard. If so, proceed to S500; if not, proceed to S600.

[0049] S500: Increase the heating temperature.

[0050] S600: Determine whether the current ambient humidity reaches the standard. If so, proceed to S700; if not, proceed to S810.

[0051] S700: Maintain the opening of the hydrogen control valve 9 and maintain the current heating temperature, and proceed to S900.

[0052] S810: Determine whether the current ambient humidity is too low. If so, proceed to S820; if not, proceed to S830.

[0053] S820: Decrease the opening of the hydrogen control valve 9 and proceed to S600.

[0054] S830: Increase the opening of the hydrogen control valve 9 and proceed to S600.

[0055] S900: End.

[0056] The working mode of the fuel cell hydrogen temperature and humidity regulation system provided by this embodiment is as follows:

[0057] The heat exchange device 6 in the coolant outlet pipeline 5 can heat the hydrogen supplied by the hydrogen storage device 7 to a certain temperature so that there is no liquid water in the gas entering the reactor. The three-way valve can achieve the switching function. When it is fully open, hydrogen passes through the hydrogen storage device 7, the hydrogen inlet pipeline 2, passes through the three-way valve, and reaches the hydrogen inlet of the fuel cell stack 1; when the three-way valve is fully closed, hydrogen passes through the hydrogen storage device 7, the hydrogen supply pipeline 5, passes through the heat exchange device 6, passes through the three-way valve, and reaches the hydrogen inlet of the fuel cell stack 1.

[0058] Under winter conditions, the gas in the hydrogen storage device 7 is close to the ambient temperature. The mixing of the low-temperature gas coming out of the hydrogen storage device 7 and the high-temperature gas in the hydrogen outlet pipeline 3 will cause the presence of condensed water. To avoid condensed water entering the reactor, it is necessary to heat the low-temperature hydrogen coming out of the hydrogen storage device 7 to a certain temperature. The three-way valve can be closed, and the low-temperature gas can be heated through the water cycle and then mixed with the high-temperature gas in the hydrogen outlet pipeline 3 before entering the reactor, regulating the temperature and humidity of the gas entering the reactor and avoiding the generation of condensed water.

[0059] Under other conditions such as in summer, if the gas passes through the heat exchange device 6, it will cause the gas temperature to be too high. After the gas coming out of the hydrogen storage device 7 is mixed with the gas in the hydrogen outlet pipeline 3, the temperature of the gas entering the reactor will continue to rise and the humidity will also decrease. At this time, it is necessary to open the three-way valve to directly mix the relatively high-temperature gas coming out of the hydrogen storage device 7 with the gas in the hydrogen outlet pipeline 3 to avoid overshoot of temperature and humidity.

[0060] The fuel cell hydrogen temperature and humidity control system provided in this embodiment uses the high-temperature liquid at the outlet of the water circulation path of the fuel cell engine to heat the hydrogen. This heat exchange structure is integrated with the water circulation pipeline through special design, and can ensure design on the original system architecture as much as possible without increasing the external contour of the system and additional design. When the engine is working, the high-temperature liquid can heat the low-temperature gas coming out of the hydrogen cylinder, with high heating efficiency. Under summer conditions, the high-temperature gas coming out of the hydrogen cylinder will also be mixed with the high-temperature gas of hydrogen reflux, resulting in the gas being too dry. Therefore, the three-way valve can be closed to directly mix the hydrogen to avoid secondary heating of the hydrogen and causing the hydrogen to be too dry. During the humidity control process, the humidity is not regulated by adjusting the hydrogen return flow rate, which can effectively avoid the loss of auxiliary component power consumption caused by the increase in the return flow rate, and at the same time avoid the negative impact that the increase in the stoichiometric ratio may bring to the fuel cell stack 1, ensuring the working performance of the fuel cell stack 1. This embodiment effectively adjusts the temperature and humidity of the hydrogen entering the reactor through the cooperation of the hydrogen control valve 9 and the heat exchange device 6 and by adjusting the opening degree of the hydrogen control valve 9 at different ambient temperatures; there are no additional complex components, effectively reducing the weight and volume of the system and improving the system performance parameters; for environmental changes, the water flow rate is not adjusted to control the temperature and humidity, protecting the fuel cell stack 1 while ensuring the temperature and humidity of the hydrogen entering the reactor.

[0061] Note that the above is only a preferred embodiment of the present invention and the technical principles applied. Those skilled in the art will understand that the present invention is not limited to the specific embodiments here, and various obvious changes, re-adjustments and substitutions can be made by those skilled in the art without departing from the protection scope of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments only. Without departing from the concept of the present invention, more other equivalent embodiments can be included, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A method for controlling the temperature and humidity of hydrogen in a fuel cell, characterized in that, The fuel cell hydrogen temperature and humidity control system includes: a fuel cell stack (1), a hydrogen storage device (7), a hydrogen inlet pipeline (2), a hydrogen outlet pipeline (3), a coolant outlet pipeline (5), a hydrogen control valve (9), and a heat exchange device (6). The fuel cell stack (1) is provided with a hydrogen inlet, a hydrogen outlet, and a coolant outlet. The hydrogen inlet pipeline (2) is connected from the hydrogen storage device (7) to the hydrogen inlet. The hydrogen outlet pipeline (3) is connected from the hydrogen outlet to the hydrogen inlet pipeline (2). The hydrogen control valve (9) is arranged at the connection of the hydrogen inlet pipeline (2) and the heat exchange device (6). The heat exchange device (6) is arranged in the coolant outlet pipeline (5), and the hydrogen inlet pipeline (2) is selectively communicated with the heat exchange device (6) through the hydrogen control valve (9). The hydrogen control valve (9) is a three-way valve. The fuel cell hydrogen temperature and humidity control system further includes a water circulation outlet (8), and the water circulation outlet (8) is arranged at the end of the coolant outlet pipeline (5). The heat exchange device (6) includes a serpentine pipe section arranged in the coolant outlet pipeline (5), and the hydrogen inlet pipeline (2) is communicated with the serpentine pipe section. The heat exchange device (6) further includes a heat exchange hydrogen inlet and a heat exchange hydrogen outlet. The hydrogen control valve (9) is arranged at the heat exchange hydrogen outlet, and whether hydrogen passes through the heat exchange device (6) is controlled by controlling the opening and closing of the hydrogen control valve (9); or, The hydrogen control valve (9) is arranged at the heat exchange hydrogen inlet, and whether hydrogen passes through the heat exchange device (6) is controlled by controlling the opening and closing of the hydrogen control valve (9). The outer wall of the coolant outlet pipeline (5) is coated with a heating film. A heating element is arranged inside the pipe wall of the coolant outlet pipeline (5). The method includes the following steps: S100: Judge whether the current ambient temperature will cause condensate to be generated. If so, enter S200; if not, enter S500. S200: Close the hydrogen control valve (9), perform hydrogen preheating, and enter S300. S300: Judge whether the condensate content entering the stack is higher than the standard. If so, enter S400; if not, enter S500. S400: Increase the heating temperature. S500: Judge whether the current ambient humidity reaches the standard. If so, enter S600; if not, enter S700. S600: Keep the opening of the hydrogen control valve (9) and keep the current heating temperature. S700: Adjust the hydrogen control valve (9) to make the ambient humidity reach the standard.

2. The fuel cell hydrogen temperature and humidity regulation method according to claim 1, wherein S700 includes the following steps: S710: Judge whether the current ambient humidity is too low. If so, enter S720; if not, enter S730. S720: Reduce the opening of the hydrogen control valve (9) and enter S500. S730: Increase the opening of the hydrogen control valve (9) and enter S500.

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