Combined heat and power system for water electrolyzer and fuel cell and control method thereof

Abstract

The present application relates to the field of hydrogen production, energy storage and cogeneration, and specifically discloses a cogeneration system for a water electrolyzer and a fuel cell and a control method thereof. The cogeneration system includes a water electrolyzer and its heat exchanger, a fuel cell and its heat exchanger, a metal hydrogen storage device and its heat exchanger, and a radiator; when the water electrolyzer is working, the heat exchange liquid can flow through the water electrolysis heat exchanger to the metal hydrogen storage heat exchanger and return to the water electrolysis heat exchanger; when the fuel cell is working, the heat exchange liquid can flow through the fuel cell heat exchanger to the metal hydrogen storage heat exchanger and return to the fuel cell heat exchanger; the radiator is arranged on the inlet side of the metal hydrogen storage heat exchanger to cool the heat exchange liquid to be input to the metal hydrogen storage heat exchanger. This is conducive to improving the energy utilization efficiency of the water electrolysis hydrogen production-metal hydrogen storage-fuel cell power generation integrated system, while meeting the cooling liquid temperature platform requirements required by the three subsystems and simplifying the design scheme of the water and heat management system.

Description

Technical Field

[0001] This application relates to the technical field of hydrogen production, energy storage, and combined heat and power (CHP), and in particular to a CHP system for water electrolyzers and fuel cells, and its control method. Background Technology

[0002] Driven by the dual-carbon goals, hydrogen energy, as a carrier of zero-carbon energy, will become an important component of China's energy system. In 2020, the National Energy Administration also included hydrogen energy in its energy category for the first time.

[0003] During the operation of fuel cells and water electrolyzers, heat is generated. Recovering this heat from the reaction process can significantly improve the system's energy efficiency. Currently, fuel cell combined heat and power (CHP) solutions exist. However, because metal hydrogen storage absorbs and releases heat during hydrogen release and absorption, and the hydrogen release temperature plateau requires a T3m (e.g., above 55°C) while the hydrogen absorption temperature plateau requires a T2m (e.g., below 40°C), a separate hydrothermal management system for the metal hydrogen storage device is required. This adds extra components, increases the difficulty of system hydrothermal management, and the heat generated during hydrogen absorption and release cannot be recovered and utilized. Summary of the Invention

[0004] This application provides a combined heat and power system for water electrolyzers and fuel cells, and its control method. The aim is to improve the energy utilization efficiency of the integrated system of water electrolysis hydrogen production, metal hydrogen storage, and fuel cell power generation, while simultaneously meeting the coolant temperature platform requirements of the three subsystems and simplifying the design of the water-thermal management system. The hydrogen energy storage method of renewable energy power generation, electrolysis hydrogen production, metal hydrogen storage, and fuel cell power generation has broad development prospects.

[0005] In a first aspect, a combined heat and power (CHP) system is provided, characterized in that the CHP system includes a water electrolyzer, a fuel cell, and a metal hydrogen storage tank, wherein the metal hydrogen storage tank stores hydrogen produced by the water electrolyzer and delivers the stored hydrogen to the fuel cell for power generation.

[0006] The combined heat and power system also includes a water electrolysis heat exchanger, a fuel cell heat exchanger, a metal hydrogen storage heat exchanger, and a radiator, wherein...

[0007] When the water electrolyzer is working, the heat exchange liquid of the combined heat and power system can flow through the water electrolyzer to the metal hydrogen storage heat exchanger and then back to the water electrolyzer.

[0008] When the fuel cell is working, the heat exchange liquid of the combined heat and power system can flow through the fuel cell heat exchanger to the metal hydrogen storage heat exchanger and then back to the fuel cell heat exchanger.

[0009] The radiator is located on the inlet side of the metal hydrogen storage heat exchanger and is used to cool the heat exchange liquid to be input into the metal hydrogen storage heat exchanger.

[0010] Compared with the prior art, the solution provided in this application has at least the following beneficial technical effects:

[0011] Compared to traditional fuel cell heat exchangers, water electrolyzers, and metal hydrogen storage heat exchangers, which are each equipped with a separate hydrothermal management system, this system has a simpler configuration and can achieve coupled control of the hydrothermal management of the three subsystems, offering significant advantages in terms of volume, weight, and energy recovery efficiency.

[0012] In conjunction with the first aspect, in certain implementations of the first aspect, the heat sink is configured to activate under any of the following conditions:

[0013] The water electrolyzer is in operation;

[0014] The fuel cell is in operation, and the temperature of the heat exchange liquid at the inlet side of the radiator is higher than the preset temperature of the fuel cell, which is 55-65°C.

[0015] The radiator can operate in different states at different stages, so that the combined heat and power system provided in this application embodiment can provide suitable heat exchange solutions for the water electrolyzer and the fuel cell respectively.

[0016] In conjunction with the first aspect, in some implementations of the first aspect, the combined heat and power system further includes a solar collector, wherein,

[0017] A portion of the heat exchange liquid output from the water electrolysis heat exchanger can bypass the metal hydrogen storage heat exchanger and flow back to the water electrolysis heat exchanger via the solar collector; and / or,

[0018] A portion of the heat exchange liquid output from the fuel cell heat exchanger can bypass the metal hydrogen storage heat exchanger and flow back to the fuel cell heat exchanger through the collector.

[0019] Combined heat and power (CHP) systems have solar collectors to collect heat and improve energy efficiency. Because the solar collectors and radiators are independently installed, the CHP system can collect heat while still meeting the operational requirements of the water electrolyzer and fuel cell.

[0020] In conjunction with the first aspect, in some implementations of the first aspect, the combined heat and power system further includes a three-way valve, wherein the outlet of the water electrolysis heat exchanger and the outlet of the fuel cell heat exchanger converge at the first port of the three-way valve, the second port of the three-way valve is connected to the inlet of the radiator, and the third port of the three-way valve is connected to the inlet of the solar collector. The three-way valve is used to control the proportion of the heat exchange liquid flow rate through the radiator to the heat exchange liquid flow rate through the first port.

[0021] The three-way valve can flexibly adjust the flow rate through the metal hydrogen storage heat exchanger and the collector, which is beneficial to increase the heat recovery rate while meeting the working requirements of the water electrolyzer and the fuel cell.

[0022] In conjunction with the first aspect, in some implementations of the first aspect, the solar collector is a hot water tank, the hot water tank including a coil for circulating heat exchange liquid, the coil being immersed in water stored in the hot water tank.

[0023] Hot water tanks can store daily water, which helps to make the recovered heat applicable to daily life and provide heat recovery value.

[0024] In conjunction with the first aspect, in some implementations of the first aspect, the heat sink is a cooling fan.

[0025] The opening of the cooling fan is easy to adjust and the heat dissipation efficiency is high, which makes it easier for the combined heat and power system to meet the usage requirements and to increase the heat recovery rate of the hot water tank.

[0026] Secondly, a control method for a combined heat and power (CHP) system is provided, the control method being used to control the CHP system as described in any of the implementations of the first aspect above, the control method comprising:

[0027] When the water electrolyzer is working, the radiator is started, and the duty cycle of the radiator is controlled according to the temperature at the outlet side of the radiator.

[0028] When the fuel cell is operating and the temperature at the outlet side of the radiator is higher than the preset temperature of the fuel cell, the radiator is activated, and the duty cycle of the radiator is controlled according to the temperature at the inlet side of the radiator.

[0029] The radiator can operate in different states at different stages, so that the combined heat and power system provided in this application embodiment can provide suitable heat exchange solutions for the water electrolyzer and the fuel cell respectively.

[0030] In conjunction with the second aspect, in some implementations of the second aspect,

[0031] When the water electrolyzer is working, the duty cycle of the radiator is equal to (the temperature at the outlet of the radiator - the preset temperature of the water electrolyzer) * 10, and the preset temperature of the water electrolyzer is 30 to 38°C.

[0032] When the fuel cell is working, the duty cycle of the radiator is (temperature at the radiator inlet side - preset temperature of the fuel cell) / 7*100, and the preset temperature of the fuel cell is 55-65℃.

[0033] Thirdly, a control method for a combined heat and power (CHP) system is provided, the control method being used to control a CHP system with a three-way valve as described in the first aspect above, the control method comprising:

[0034] When the water electrolyzer is working, the opening degree of the second port of the three-way valve is controlled to be the first opening degree;

[0035] When the fuel cell is operating, the opening degree of the second port is controlled according to the heat exchange liquid temperature at the inlet side of the radiator, the heat exchange liquid temperature at the outlet side of the radiator, and / or the heat exchange liquid temperature of the collector.

[0036] The three-way valve can flexibly adjust the flow rate through the metal hydrogen storage heat exchanger and the collector, which is beneficial to increase the heat recovery rate while meeting the working requirements of the water electrolyzer and the fuel cell.

[0037] In conjunction with the third aspect, in some implementations of the third aspect, the first opening degree is 40% to 60%.

[0038] In conjunction with the third aspect, in some implementations of the third aspect,

[0039] When the fuel cell is operating, when T3 < 50℃ and T6 - T2 ≤ 15℃, the opening degree of the second port is 60% to 100%.

[0040] When the fuel cell is operating, when T3 < 50°C and T6 - T2 > 15°C, the opening degree of the second port is 40% to 60%.

[0041] When the fuel cell is working, when T3≥50℃ and T2≤62℃, the opening degree of the second port is 100-(T2-52)*10;

[0042] When the fuel cell is operating, the opening degree of the second port is 100% when T3 ≥ 50℃ and T2 > 62℃.

[0043] Wherein, T2 is the heat exchange liquid temperature at the inlet side of the radiator, T3 is the heat exchange liquid temperature at the outlet side of the radiator, and T6 is the heat exchange liquid temperature of the collector.

[0044] Fuel cells have relatively relaxed temperature requirements. Different control methods can be designed for different operating conditions, which can enable combined heat and power systems to have both high-efficiency heat exchange and heat recovery performance.

[0045] Fourthly, a controller for use in a combined heat and power system is provided, the controller being used to execute the control method as described in any of the implementations of the second to third aspects above. Attached Figure Description

[0046] Figure 1 This is a schematic structural diagram of a combined heat and power system provided in an embodiment of this application.

[0047] Figure 2 This is a schematic structural diagram of a control method for a combined heat and power system provided in an embodiment of this application.

[0048] Figure 3 A schematic structural diagram of another combined heat and power system provided in this application embodiment.

[0049] Figure 4 A schematic structural diagram of another control method for a combined heat and power system provided in an embodiment of this application. Detailed Implementation

[0050] The present application will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0051] In order to improve the energy utilization efficiency of the integrated system of water electrolysis hydrogen production-metal hydrogen storage-fuel cell power generation, while meeting the coolant temperature platform requirements of the three subsystems and simplifying the design of the water-thermal management system, this invention provides a combined heat and power system and its control method.

[0052] Figure 1 This is a schematic structural diagram of a combined heat and power system provided in an embodiment of this application.

[0053] A combined heat and power (CHP) system includes a water electrolyzer, a fuel cell, and a metal hydrogen storage tank. The metal hydrogen storage tank stores the hydrogen produced by the water electrolyzer and delivers the stored hydrogen to the fuel cell for power generation. The CHP system also includes a water electrolysis heat exchanger, a fuel cell heat exchanger, a metal hydrogen storage heat exchanger, and a radiator. The water electrolyzer and the fuel cell do not operate simultaneously. When the water electrolyzer is operating, the heat exchange fluid of the CHP system flows from the water electrolysis heat exchanger to the metal hydrogen storage heat exchanger and back to the water electrolysis heat exchanger, thus the water electrolyzer heat exchanger is used for heat exchange between the water electrolyzer and the CHP system coolant. When the fuel cell is operating, the heat exchange fluid of the CHP system flows from the fuel cell heat exchanger to the metal hydrogen storage heat exchanger and back to the fuel cell heat exchanger, thus the fuel cell heat exchanger is used for heat exchange between the fuel cell and the CHP system coolant.

[0054] A radiator is installed on the inlet side of the metal hydrogen storage heat exchanger to cool the heat exchange liquid to be input into the metal hydrogen storage heat exchanger. Figure 1 In the illustrated embodiment, the heat sink can be a cooling fan. This application uses a cooling fan as an example for explanation. A cooling fan can be used to dissipate excess heat from a combined heat and power (CHP) system, particularly when a water electrolyzer is operating, to cool the inlet fluid of a metal hydrogen storage heat exchanger to the required temperature.

[0055] refer to Figure 1 The pressure and flow rate of the combined heat and power (CHP) circuit can be regulated by a water pump to ensure the cooling flow rate of the circulation system. The heat exchange liquid output from the metal hydrogen storage heat exchanger can be diverted to the water electrolyzer heat exchanger and the fuel cell heat exchanger. Temperature sensors T1 can be installed on the inlet side of the water electrolyzer heat exchanger and the fuel cell heat exchanger to detect the secondary circulating water temperature. Temperature sensor T2 can be installed on the inlet side of the radiator to detect the secondary circulating water temperature flowing into the radiator. Temperature sensor T3 can be installed on the outlet side of the radiator to detect the secondary circulating water temperature output from the radiator to the metal hydrogen storage heat exchanger.

[0056] When the water electrolyzer is operating, the secondary circulating water temperature of the water electrolyzer heat exchanger must not exceed T1m. The metal hydrogen storage heat exchanger operates in a hydrogen absorption state, releasing heat, and to meet the hydrogen absorption rate and pressure requirements, the fluid temperature must not exceed T2m. When the fuel cell heat exchanger is operating, the metal hydrogen storage heat exchanger operates in a hydrogen release state, absorbing heat, and to meet the hydrogen release rate and pressure requirements, the fluid temperature must not be lower than T3m. Wherein, T3m > T1m > T2m and T3m - T2m > 10°C. In some embodiments, the combined heat and power system may further include a controller, which can be used to regulate the radiator based on the temperature signal fed back by the temperature sensor, so that the heat exchange liquid temperature of the metal hydrogen storage heat exchanger meets the operating requirements.

[0057] Figure 2 This is a schematic flowchart of a control method for a combined heat and power system provided in an embodiment of this application. Figure 2 The control method shown can be applied to Figure 1 The combined heat and power system shown.

[0058] 110. When the water electrolyzer is working, start the radiator and control the radiator's duty cycle according to the temperature on the radiator outlet side.

[0059] 120. When the fuel cell is working and the temperature at the radiator outlet is higher than the preset temperature of the fuel cell, the radiator is started, and the duty cycle of the radiator is controlled according to the temperature at the radiator inlet.

[0060] The following combination Figure 2 To elaborate in detail.

[0061] The water electrolyzer releases heat, requiring the coolant temperature to not exceed T1m; the metal hydrogen storage heat exchanger releases heat during hydrogen absorption, requiring the temperature to not exceed T2m. Ideally, there should be a significant temperature difference between the fluid temperatures at the water electrolyzer heat exchanger and the metal hydrogen storage heat exchanger. Specifically, the fluid temperature at the water electrolyzer heat exchanger should be high to ensure the overall temperature of the circulating water, while the fluid temperature at the metal hydrogen storage heat exchanger should be low to ensure the hydrogen charging pressure for the metal hydrogen storage system. To achieve this, the opening of the cooling fan is adjusted to increase the temperature difference between the fan inlet and outlet, thus obtaining the low-temperature fluid required for metal hydrogen storage.

[0062] Therefore, upon entering the water electrolyzer operating state, the cooling fan opening is adjusted in real time according to the current fluid temperature at the metal hydrogen storage heat exchanger. When the current fluid temperature at the metal hydrogen storage heat exchanger is sufficiently low, the cooling fan does not start. As the fluid temperature at the metal hydrogen storage heat exchanger rises to a certain temperature, the cooling fan starts. The higher the fluid temperature, the larger the cooling fan opening. When T2 rises to a certain high temperature, the cooling fan opening is 100%. In some embodiments, when the water electrolyzer is working, the duty cycle of the radiator = (T3 - preset water electrolyzer temperature) * 10, where the preset water electrolyzer temperature can be 30–38°C.

[0063] The fuel cell releases heat, while the metal hydrogen storage heat exchanger absorbs heat during the hydrogen release process. The required temperature is not lower than T3m; otherwise, it will affect the hydrogen release pressure of the metal hydrogen storage heat exchanger. In other words, the cooling fan does not start when the circulating water temperature has not reached T3m. When the circulating water temperature reaches T3m, the cooling fan opening increases with the increase in circulating water temperature. The decision to activate the cooling fan is based on whether the heat exchange liquid temperature T2 at the cooling fan inlet side is higher than the fuel cell preset temperature (e.g., 50–70°C, specifically 55–65°C, such as 60°C). When T2 rises to a certain high temperature, the cooling fan opening is 100%. In some embodiments, when the fuel cell is operating, the radiator duty cycle = (T2 - fuel cell preset temperature) / 7 * 100.

[0064] Figure 3 This is a schematic structural diagram of another combined heat and power system provided in the embodiments of this application.

[0065] and Figure 1 The combined heat and power systems shown are different. Figure 3 The illustrated combined heat and power (CHP) system may also include a solar collector. In one possible implementation, a portion of the heat exchange liquid output from the water electrolysis heat exchanger can be fed not only to the metal hydrogen storage heat exchanger but also to the solar collector. The heat exchange liquid output from the solar collector can flow back to the water electrolysis heat exchanger. That is, the heat exchange liquid can bypass the radiator and the metal hydrogen storage heat exchanger, flowing back from the solar collector to the water electrolysis heat exchanger. In another possible implementation, a portion of the heat exchange liquid output from the fuel cell heat exchanger can be fed not only to the metal hydrogen storage heat exchanger but also to the solar collector. The heat exchange liquid output from the solar collector can flow back to the fuel cell heat exchanger. That is, the heat exchange liquid can bypass the radiator and the metal hydrogen storage heat exchanger, flowing back from the solar collector to the fuel cell heat exchanger. Figure 3 In the embodiments shown, both the water electrolysis heat exchanger and the fuel cell heat exchanger can achieve heat recovery by outputting heat exchange liquid to the collector.

[0066] In some embodiments, the collector can be a hot water collection tank. The hot water collection tank contains coils and is covered with insulation material to collect heat from the combined heat and power system to meet the hot water demand of the downstream system. The coils can be immersed in the water stored in the hot water collection tank, thereby conducting heat from the coils to the water in the tank, achieving effective heat collection.

[0067] Furthermore, with Figure 1 The combined heat and power systems shown are different. Figure 3The combined heat and power (CHP) system shown may also include a three-way valve. The outlets of the water electrolysis heat exchanger and the fuel cell heat exchanger converge at the first port of the three-way valve. The second port of the three-way valve is connected to the inlet of the radiator, and the third port is connected to the inlet of the heat collector. The three-way valve is used to control the ratio of the heat exchange fluid flow through the radiator to the heat exchange fluid flow through the first port. In other words, the three-way valve can be used to regulate the fluid ratio passing through the metal hydrogen storage heat exchanger and the heat collection tank.

[0068] In some embodiments, the metal hydrogen storage heat exchanger absorbs heat during hydrogen release (when the fuel cell heat exchanger is operating), requiring a temperature above T3m; and releases heat during hydrogen absorption (when the water electrolyzer is operating), requiring a temperature below T2m. The combined heat and power system may also include a controller, which can be used to regulate the radiator and / or three-way valve based on temperature signals fed back from temperature sensors, so that the heat exchange liquid temperature of the metal hydrogen storage heat exchanger meets the operating requirements.

[0069] In one possible implementation, it can be achieved by... Figure 2 The control method shown uses a controller to adjust the duty cycle of the radiator in order to regulate the starting power (opening degree) of the radiator.

[0070] In another possible implementation, it can be done by Figure 4 The control method shown uses a controller to regulate the three-way valve to adjust the fluid ratio passing through the metal hydrogen storage heat exchanger and the hot water collection tank.

[0071] Figure 4 This application provides a schematic flowchart of a control method for a combined heat and power system. Figure 4 The control method shown can be applied to Figure 3 The combined heat and power system shown. In some embodiments, Figure 4 The control method shown can be used with Figure 2 The control methods shown are executed simultaneously or sequentially.

[0072] 130. When the water electrolyzer is working, the opening degree of the second port of the three-way valve is controlled to be the first opening degree.

[0073] 140. When the fuel cell is working, the opening degree of the second port is controlled according to the heat exchange liquid temperature on the inlet side of the radiator, the heat exchange liquid temperature on the outlet side of the radiator and / or the heat exchange liquid temperature of the collector.

[0074] The following combination Figure 4 To elaborate in detail.

[0075] 1. When the water electrolyzer is running:

[0076] The water electrolyzer releases heat, requiring the coolant temperature to not exceed T1m; the metal hydrogen storage heat exchanger releases heat during hydrogen absorption, requiring the temperature to not exceed T2m. Ideally, there should be a significant temperature difference between the fluid temperatures at the water electrolyzer heat exchanger and the metal hydrogen storage heat exchanger. Specifically, the fluid temperature at the water electrolyzer heat exchanger should be higher to ensure the overall temperature of the circulating water and to achieve heat recovery through the hot water tank; the fluid temperature at the metal hydrogen storage heat exchanger should be lower to ensure the hydrogen charging pressure of the metal hydrogen storage tank.

[0077] To achieve this goal, the flow rate of the circulating water in the metal hydrogen storage system is reduced by adjusting the opening of the three-way valve, thereby increasing the temperature difference between the inlet and outlet of the cooling fan and obtaining the low-temperature fluid required for metal hydrogen storage. Optionally, the opening of the cooling fan can also be increased to further increase the temperature difference between the inlet and outlet of the cooling fan and obtain the low-temperature fluid required for metal hydrogen storage. In this case, the flow rate through the hot water tank is relatively large, enabling heat recovery from the water electrolyzer and the metal hydrogen storage heat exchanger.

[0078] Once the water electrolyzer is in operation, the opening degree of the second port of the three-way valve, i.e., the proportion of heat exchange liquid flowing into the metal hydrogen storage heat exchanger, can reach the first opening degree. This first opening degree can be 40% to 60%. In one possible implementation, the opening degree of the three-way valve can be adjusted so that the circulating flow rate through the metal hydrogen storage heat exchanger is the minimum flow rate required to meet the heat dissipation capacity of the metal hydrogen storage. Optionally, in conjunction with... Figure 2 In the embodiment shown, the opening of the cooling fan is adjusted in real time according to the current fluid temperature at the metal hydrogen storage heat exchanger. When the current fluid temperature at the metal hydrogen storage heat exchanger is low enough, the cooling fan does not start. When the fluid temperature at the metal hydrogen storage heat exchanger rises to a certain temperature, the cooling fan starts. The higher the fluid temperature, the larger the opening of the cooling fan. When T2 rises to a certain high temperature, the opening of the cooling fan is 100%.

[0079] 2. When the fuel cell is operating:

[0080] Fuel cells release heat, requiring the coolant temperature to not exceed T1m; the metal hydrogen storage heat exchanger absorbs heat during hydrogen release, requiring a temperature not lower than T3m, otherwise it will affect the hydrogen release pressure of the metal hydrogen storage heat exchanger. The opening degree of the second port, i.e., the proportion of heat exchanger liquid flowing into the metal hydrogen storage heat exchanger, is controlled based on the heat exchanger liquid temperatures at the inlet and outlet of the radiator and / or the heat exchanger liquid temperatures of the collector.

[0081] When the circulating water temperature has not reached T3m (e.g., 50℃), the temperature inside the hot water collector is monitored. If the temperature of the hot water collector is much higher than that of the circulating water (e.g., T6-T2 > 15℃), the opening of the second port of the three-way valve is adjusted to 40%–60%, so that approximately half of the circulating water flows through the metal hydrogen storage heat exchanger and approximately half flows through the hot water collector. At this time, the heat in the hot water collector is conducted to the circulating water through the coil, raising the temperature of the circulating water. If the temperature difference between the hot water collector and the circulating water is not significant (e.g., T6-T2 ≤ 15℃), the opening of the three-way valve is adjusted so that most of the circulating water (e.g., 60%–100%) flows through the metal hydrogen storage heat exchanger, and the heat generated by the fuel cell rapidly raises the temperature of the secondary circulating water.

[0082] When the circulating water temperature reaches T3m, it is only necessary to ensure that the circulating water temperature does not exceed T1m. When the circulating water temperature is slightly higher than T3m (e.g., T3 ≥ 50℃ and T2 ≤ 62℃), as the circulating water temperature rises, the opening of the three-way valve can be gradually adjusted to increase the circulation flow through the hot water collection tank. The opening of the three-way valve is adjusted so that the circulation flow through the metal hydrogen storage heat exchanger is equal to the minimum flow rate required to absorb heat from the metal hydrogen storage. In one possible implementation, the opening of the second port can be 100 - (T2 - 52) * 10. This not only dissipates the heat from the heating system but also recovers and reuses the heat, improving energy utilization. As the circulating water temperature rises, when the circulating water temperature is much higher than T3m (e.g., T3 ≥ 50℃ and T2 > 62℃), the hot water collection tank circuit is closed, and all the circulating water flows through the cooling fan and the metal hydrogen storage heat exchanger, with the heat dissipated through the cooling fan. That is, the opening of the second port can be 100%. In some embodiments, combined with Figure 2 In the embodiment shown, as the temperature of the circulating water increases, the opening of the cooling fan can be gradually increased to dissipate excess heat.

[0083] The following embodiments illustrate a specific solution provided in this application.

[0084] Example 1

[0085] The following section introduces abbreviations.

[0086] T1m: The maximum allowable secondary circulating water temperature for fuel cells and water electrolyzers, taken as 50℃.

[0087] T2m: The maximum allowable circulating water temperature for a metal hydrogen storage heat exchanger that absorbs hydrogen and releases heat at the rated flow rate is 40℃.

[0088] T3m: The minimum allowable circulating water temperature for a metal hydrogen storage heat exchanger to release hydrogen and absorb heat at its rated flow rate is 55℃.

[0089] T1: Temperature of circulating water flowing through the fuel cell and water electrolyzer.

[0090] T2: Temperature of the circulating water flowing through the cooling fan.

[0091] T3: Temperature of the circulating water flowing through the metal hydrogen storage heat exchanger.

[0092] T6: Fluid temperature inside the hot water tank.

[0093] Three-way valve opening: continuously adjustable; 0% flow rate passes through the hot water collection tank; 100% flow rate passes through the metal hydrogen storage tank.

[0094] Cooling fan: duty cycle controlled, range from 0 to 100%.

[0095] After the system is powered on, it performs a self-test to determine whether the fuel cell heat exchanger or the water electrolyzer is working. Based on the result, it enters the corresponding subroutine.

[0096] 1. When the water electrolyzer is running:

[0097] Start the water pump; target temperature T3 is 38℃; adjust the three-way valve opening to 40%; cooling fan duty cycle = (T3-34)*10. Continue until the water electrolyzer stops working, then return to the main program.

[0098] 2. When the fuel cell power generation system is operating:

[0099] Start the water pump and open the three-way valve to 100% (all circulating water flows through the metal hydrogen storage tank).

[0100] Determine the temperature T3. If T3 < 50℃ and T6 - T2 ≤ 15℃, keep the three-way valve open at 100% and the cooling fan will not start. If T3 < 50℃ and T6 - T2 > 15℃, keep the three-way valve open at 50% and the cooling fan will not start.

[0101] If T3 ≥ 50℃ and the target T2 = 60℃, determine if the temperature of T2 is greater than 62℃. If T2 ≤ 62℃, the target opening of the three-way valve is 100 - (T2 - 52) * 10, and the duty cycle of the cooling fan is (T2 - 59) / 7 * 100. If T2 > 62℃, the opening of the three-way valve is 100%, and the duty cycle of the cooling fan is (T2 - 59) / 7 * 100.

[0102] Return to the main program until the fuel cell stops working.

[0103] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims of the present invention.

Claims

1. A combined heat and power system, characterized in that, The combined heat and power system includes a water electrolyzer, a fuel cell, and a metal hydrogen storage tank. The metal hydrogen storage tank stores the hydrogen produced by the water electrolyzer and delivers the stored hydrogen to the fuel cell to generate electricity. The combined heat and power system also includes a water electrolysis heat exchanger, a fuel cell heat exchanger, a metal hydrogen storage heat exchanger, and a radiator, wherein... When the water electrolyzer is working, the heat exchange liquid of the combined heat and power system can flow through the water electrolyzer to the metal hydrogen storage heat exchanger and then back to the water electrolyzer. When the fuel cell is working, the heat exchange liquid of the combined heat and power system can flow through the fuel cell heat exchanger to the metal hydrogen storage heat exchanger and then back to the fuel cell heat exchanger. The radiator is located on the inlet side of the metal hydrogen storage heat exchanger and is used to cool the heat exchange liquid to be input into the metal hydrogen storage heat exchanger.

2. The combined heat and power system according to claim 1, characterized in that, The radiator is used to activate under any of the following conditions: The water electrolyzer is in operation; The fuel cell is in operation, and the temperature of the heat exchange liquid at the inlet side of the radiator is higher than the preset temperature of the fuel cell, which is 55-65°C.

3. The combined heat and power system according to claim 1, characterized in that, The combined heat and power system also includes a solar collector, wherein... A portion of the heat exchange liquid output from the water electrolysis heat exchanger can bypass the metal hydrogen storage heat exchanger and flow back to the water electrolysis heat exchanger via the solar collector; and / or, A portion of the heat exchange liquid output from the fuel cell heat exchanger can bypass the metal hydrogen storage heat exchanger and flow back to the fuel cell heat exchanger through the collector.

4. The combined heat and power system according to claim 3, characterized in that, The combined heat and power system also includes a three-way valve. The outlet of the water electrolysis heat exchanger and the outlet of the fuel cell heat exchanger meet at the first port of the three-way valve. The second port of the three-way valve is connected to the inlet of the radiator, and the third port of the three-way valve is connected to the inlet of the solar collector. The three-way valve is used to control the proportion of the heat exchange liquid flow rate through the radiator to the heat exchange liquid flow rate through the first port.

5. The combined heat and power system according to claim 3 or 4, characterized in that, The collector is a hot water tank, which includes a coil for circulating heat exchange liquid, and the coil is immersed in the water stored in the hot water tank.

6. The combined heat and power system according to claim 1, characterized in that, The radiator is a cooling fan.

7. A control method for a combined heat and power system, characterized in that, The control method is used to control the combined heat and power system as described in any one of claims 1 to 6, and the control method includes: When the water electrolyzer is working, the radiator is started, and the duty cycle of the radiator is controlled according to the temperature at the outlet side of the radiator. When the fuel cell is operating and the temperature at the outlet side of the radiator is higher than the preset temperature of the fuel cell, the radiator is activated, and the duty cycle of the radiator is controlled according to the temperature at the inlet side of the radiator.

8. The control method according to claim 7, characterized in that, When the water electrolyzer is working, the duty cycle of the radiator is equal to (the temperature at the outlet of the radiator - the preset temperature of the water electrolyzer) * 10, and the preset temperature of the water electrolyzer is 30 to 38°C. When the fuel cell is working, the duty cycle of the radiator is (temperature at the radiator inlet side - preset temperature of the fuel cell) / 7*100, and the preset temperature of the fuel cell is 55-65℃.

9. A control method for a combined heat and power system, characterized in that, The control method is used to control the combined heat and power system as described in claim 5, and the control method includes: When the water electrolyzer is working, the opening degree of the second port of the three-way valve is controlled to the first opening degree; when the fuel cell is working, the opening degree of the second port is controlled according to the heat exchange liquid temperature at the inlet side of the radiator, the heat exchange liquid temperature at the outlet side of the radiator, and / or the heat exchange liquid temperature of the collector.

10. The control method according to claim 9, characterized in that, The first opening degree is 40% to 60%.

11. The control method according to claim 9 or 10, characterized in that, When the fuel cell is operating, when T3 < 50℃ and T6 - T2 ≤ 15℃, the opening degree of the second port is 60% to 100%. When the fuel cell is operating, when T3 < 50°C and T6 - T2 > 15°C, the opening degree of the second port is 40% to 60%. When the fuel cell is working, when T3≥50℃ and T2≤62℃, the opening degree of the second port is 100-(T2-52)*10; When the fuel cell is operating, the opening degree of the second port is 100% when T3 ≥ 50℃ and T2 > 62℃. Wherein, T2 is the heat exchange liquid temperature at the inlet side of the radiator, T3 is the heat exchange liquid temperature at the outlet side of the radiator, and T6 is the heat exchange liquid temperature of the collector.

12. A controller for a combined heat and power system, characterized in that, The controller is used to perform the control method as described in any one of claims 7 to 11.

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