Heat management system for solid-state hydrogen storage fuel cell, forklift and control method

Abstract

The application discloses a kind of solid-state hydrogen storage fuel cell heat management system, fork truck and control method, it includes the heater being arranged in hydrogen storage system, and the cooler being arranged in fuel cell stack, the outlet of the cooler is connected with heating device, radiator respectively by three-way reversing valve, the outlet of heating device, radiator is connected with the water inlet of cooler, to form stack cooling circuit and stack preheating circuit;Water-water heat exchanger is connected between the inlet and outlet of the heater, the two ends of one pipe in water-water heat exchanger are connected with the inlet and outlet of the heater respectively, the two ends of another pipe are connected with the inlet and outlet of the cooler respectively, to form hydrogen storage heat exchange circuit.The heat generated when fuel cell stack operates is used to heat hydrogen storage system through hydrogen storage heat exchange circuit in the application, and heat energy is fully utilized;Meanwhile, hydrogen storage system can supply hydrogen normally after preheating, so that the vehicle enters the best working state at the fastest speed.

Description

Technical Field

[0001] This invention belongs to the field of battery technology, specifically relating to a thermal management system, forklift, and control method for solid-state hydrogen storage fuel cells. Background Technology

[0002] Hydrogen energy, as a clean and efficient new energy source, is increasingly being used in hydrogen fuel cell forklifts. Since forklifts are widely used in ports, warehouses, and other locations with small operating radii and high throughput, these operating scenarios are very suitable for using hydrogen fuel cell power systems to provide clean and efficient power.

[0003] Currently, hydrogen fuel cells mostly use gaseous hydrogen storage, which involves storing hydrogen at a certain pressure in high-pressure cylinders. When needed, the high-pressure hydrogen is depressurized through a pressure reducing valve before being supplied to the fuel cell. However, gaseous hydrogen storage fuel cell forklifts face difficulties in using hydrogen due to limitations such as the construction of hydrogen refueling stations in factory areas. Furthermore, the high hydrogen storage pressure (typically reaching 35MPa or even 70MPa) poses a risk of high-pressure explosion, hindering its widespread application in industrial settings.

[0004] Solid-state hydrogen storage utilizes solid hydrogen storage materials (such as common metal hydrides). When hydrogen needs to be released, simply heating the storage material promotes the desorption and release of hydrogen from the metal lattice. Therefore, solid-state hydrogen storage operates at low pressure (less than 5 MPa), eliminating the risk of high-pressure deflagration and ensuring high safety. Furthermore, the weight of solid-state hydrogen fuel cells allows them to be used as counterweights in forklifts, enabling functional integration. Thus, solid-state hydrogen fuel cell forklifts have become an important development direction for hydrogen-powered industrial vehicles.

[0005] The solid-state hydrogen fuel cell forklift system mainly includes a fuel cell system, a power battery component, and a hydrogen storage and buffer component. The hydrogen fuel cell system comprises a hydrogen storage system and a fuel cell stack. The hydrogen storage system includes a solid-state hydrogen storage tank and an insulated box. The solid-state hydrogen storage tank is placed inside the insulated box and contains hydrogen storage material. Its outlet is connected to a pressure reducing valve.

[0006] When a hydrogen fuel cell system is operating, the hydrogen storage system releases hydrogen gas after the storage material is heated. This hydrogen gas passes through a pressure reducing valve and is then fed into the anode of the fuel cell stack. Simultaneously, air enters the cathode of the fuel cell stack through an air intake system. Under the action of the anode catalyst, hydrogen gas decomposes into protons and electrons. Protons pass through the proton exchange membrane to the cathode, while electrons generate current through an external circuit, producing electrical energy. At the cathode, protons and electrons react with oxygen in the air to produce water. Part of the electrical energy generated directly powers the forklift, while the other part can be stored in the battery.

[0007] However, current solid-state hydrogen fuel cell forklifts generally suffer from difficulties in releasing hydrogen from their storage systems at low temperatures. The hydrogen release process is essentially an endothermic reaction, where metal hydrides decompose and release hydrogen gas upon heating. The reaction rate and hydrogen release volume are highly temperature-dependent; higher temperatures result in higher equilibrium pressures of the metal hydrides and faster release rates, while lower temperatures lead to lower equilibrium pressures and make the reaction more difficult. In practical applications, when the ambient temperature drops below 0°C, the hydrogen release volume of the storage system decreases sharply, failing to meet the hydrogen flow and pressure requirements for normal operation of the fuel cell system. This hinders the widespread application of solid-state hydrogen fuel cell forklifts in cold regions.

[0008] To address the challenge of low-temperature hydrogen release from solid-state hydrogen fuel cell forklifts, several technological explorations have been undertaken. For example, some solutions employ external electric heating to preheat the hydrogen storage system, but this requires additional electrical energy, increasing overall vehicle energy consumption. Other solutions utilize the waste heat from the cooling water generated during fuel cell stack operation to heat the hydrogen storage system. However, fuel cell stacks themselves face difficulties starting at low temperatures, typically operating within a range of 0-80°C. Therefore, before the stack generates sufficient heat, it cannot provide an effective heat source for the hydrogen storage system. Furthermore, due to the high maintenance and replacement costs of fuel cell stacks, the cooling water used must be kept clean to prevent contamination that could impact the stack's lifespan. Therefore, directly heating the hydrogen storage system with the fuel cell stack's cooling water would contaminate the cooling water and affect the fuel cell stack's performance.

[0009] Therefore, there is an urgent need to develop a thermal management system and preheating control method for solid-state hydrogen storage fuel cells that can effectively solve the problem of hydrogen release from hydrogen storage systems under low-temperature conditions and achieve efficient energy utilization of the system. Summary of the Invention

[0010] The purpose of this invention is to solve the above-mentioned problems by providing a thermal management system, forklift, and preheating control method for solid-state hydrogen storage fuel cells. This not only solves the problem of effectively releasing hydrogen from the hydrogen storage system under low-temperature conditions, but also makes efficient use of the system energy.

[0011] The technical solution of this invention is as follows: The first objective of this invention is to provide a thermal management system for a solid hydrogen storage fuel cell, including a heater installed in the hydrogen storage system to preheat the hydrogen storage tank, and a cooler installed on the periphery of the fuel cell stack to cool it. The outlet of the cooler is connected to a heating device and a radiator respectively through a three-way reversing valve. The outlets of the heating device and the radiator are both connected to the inlet of the cooler, thereby forming a stack cooling circuit and a stack preheating circuit. A water-to-water heat exchanger is connected in series between the inlet and outlet of the heater. The water-to-water heat exchanger has two independent pipelines. One pipeline is connected to the inlet and outlet of the heater at both ends, and the other pipeline is connected to the inlet and outlet of the cooler at both ends, thereby forming a hydrogen storage heat exchange circuit.

[0012] In a further embodiment, the outlets of the heating device and the radiator are both connected to the inlet of the cooler via a second water pump; a filter is connected in series between the radiator and the second water pump.

[0013] In a further embodiment, a deionizer is connected between the outlet of the second water pump and the inlet of the three-way reversing valve.

[0014] In a further embodiment, temperature detectors for detecting liquid temperature are installed at both the outlet of the cooler and the inlet of the heater.

[0015] In a further embodiment, a first water pump is connected in series between the inlet of the heater and the water-to-water heat exchanger, and a one-way valve is connected between the outlet of the water-to-water heat exchanger and the outlet of the cooler, so that the hot water before entering the cooler enters the water-to-water heat exchanger for heat exchange and then merges with the water at the outlet of the cooler.

[0016] A further embodiment also includes a vehicle control unit (VCU), a fuel cell control unit (FCU), instruments, and a power battery on the forklift. The power battery is connected to the vehicle control unit via a BMS. The vehicle control unit is connected to the fuel cell control unit and the instruments. The fuel cell control unit controls the operation or shutdown of the stack cooling circuit, the stack preheating circuit, and the hydrogen storage heat exchange circuit.

[0017] In a further embodiment, the fuel cell stack is electrically connected to the vehicle power supply and the power battery via a DC-DC converter to provide operating power.

[0018] A second objective of this invention is to provide a forklift equipped with a thermal management system for a solid hydrogen fuel cell as described above.

[0019] A third objective of this invention is to provide a control method for the thermal management system of the aforementioned solid-state hydrogen storage fuel cell, comprising the following steps: S1. Set the temperature A when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to idle, the temperature B when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to operate normally, and the temperature C when the fuel cell stack operates normally. S2. Collect the liquid temperature t1 in the hydrogen storage heat exchange circuit and the liquid temperature t2 at the fuel cell stack outlet, respectively, and t1≤t2; When t2 < Cmin and t1 < A, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit work simultaneously, preheating the fuel cell stack while exchanging heat with the hydrogen storage system, causing the temperatures of both the fuel cell stack and the hydrogen storage system to rise. When t2>Cmin and A≤t1<B, the fuel cell stack preheating circuit and hydrogen storage heat exchange circuit continue to work, causing the temperature of the fuel cell stack and hydrogen storage system to continue to rise. S3. When t1≥B, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit continue to work until t1≥B+5. Then, the heating device in the fuel cell stack preheating circuit is turned off, and the liquid temperature in the hydrogen storage heat exchange circuit will gradually decrease. When t1≤B, the heating device in the fuel cell stack preheating circuit restarts. This cycle continues to ensure that B≤t1≤B+5. When the fuel cell stack is started at this time, the output power of the fuel cell stack is 100%. S4. After the fuel cell stack is started, when t2≥Cmax, the stack cooling circuit is turned on to cool it. At the same time, some of the hot water in the cooling circuit enters the hydrogen storage heat exchange circuit to preheat the hydrogen storage system. When t2 < Cmax, shut down the fuel cell stack cooling water circuit.

[0020] In a further scheme, in step S2, when t2>Cmin and A≤t1<B, the heating device in the fuel cell stack preheating circuit is turned off. At this time, the fuel cell stack is allowed to start. During the process of t1 rising from A to B, the output power of the fuel cell stack is linearly positively correlated with t1, that is, the output power of the fuel cell stack increases linearly from 10% to 100% of the rated power. When the fuel cell stack is working, the heat it generates continuously heats the hydrogen storage system through the hydrogen storage heat exchange circuit. In step s3, when t1≥B, the heating device in the fuel cell stack preheating circuit is turned off. At this time, the fuel cell stack is allowed to start, and the fuel cell stack can output 100% power.

[0021] In a further embodiment, the power supply for the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit is provided by the power battery, and their startup is predicated on the power battery charging signal, i.e.: When a charging signal is detected that the power battery is connected to an external power source, the stack preheating circuit and the hydrogen storage heat exchange circuit are simultaneously activated. When the power battery is not being charged, the fuel cell preheating circuit and the hydrogen storage heat exchange circuit are simultaneously shut down.

[0022] This application utilizes the heat generated during the preheating or operation of the fuel cell stack to heat the hydrogen storage system through a hydrogen storage heat exchange circuit. This fully utilizes thermal energy and significantly improves the hydrogen release rate of the hydrogen fuel cell system. At the same time, the hydrogen storage system can supply hydrogen normally after preheating, allowing the vehicle to enter its optimal working state at the fastest speed.

[0023] This application utilizes a water-to-water heat exchanger with two independent pipelines to exchange heat between the circulating fluid during fuel cell stack preheating or operation, and then heats the hydrogen storage system. This separates the circulating fluid in the fuel cell stack from that in the hydrogen storage system, preventing contamination of the fuel cell stack's circulating fluid by the hydrogen storage system's circulating fluid, ensuring the cleanliness of the fuel cell stack's circulating fluid, and improving the fuel cell stack's lifespan.

[0024] Because the circulating fluid in the thermal management system has a large capacity, the power consumption required for preheating at low temperatures is significant, which is generally insufficient for the capacity of the equipped power battery. Therefore, to prevent excessive power consumption during preheating from causing battery depletion, especially cell undervoltage and starvation, the aforementioned preheating function must be performed while the power battery is plugged into the charging gun. Thus, this application avoids the aforementioned situation by requiring the activation of both the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit to be triggered by the power battery charging signal.

[0025] The control method of the thermal management system in this application uses real-time temperature detection to control the opening and closing of the fuel cell preheating circuit, fuel cell cooling circuit and hydrogen storage heat exchange circuit, which ensures the normal operation of the hydrogen fuel cell and avoids energy waste. Attached Figure Description

[0026] 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 only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the loop in this invention; Figure 2 This is a circuit diagram of the present invention.

[0028] The annotations in the attached figures are explained as follows: 1-Hydrogen storage system, 11-First temperature sensor, 12-Heating replenishment tank, 13-First water pump, 14-Water-water heat exchanger, 15-One-way valve; 2-Fuel cell stack, 21-Three-way reversing valve, 22-Heating device, 23-Radiator, 24-Filter, 25-Second water pump, 26-Deionizer, 27-Coolant replenishment tank, 28-Second temperature sensor Detailed Implementation To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. The described embodiments are merely some embodiments of this invention, and not all embodiments. All other implementations obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0029] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0030] Example 1: This embodiment describes a solid-state hydrogen storage fuel cell, which includes a hydrogen storage system and a fuel cell stack. The hydrogen storage system includes an insulated box and a tank containing hydrogen storage material built into the insulated box, as well as a heater for heating the tank. When heated, the hydrogen storage material releases hydrogen gas, which is then fed into the anode of the fuel cell stack via a pressure reducing valve and a proportional valve. Simultaneously, air enters the cathode of the fuel cell stack through an air intake system. Under the action of the anode catalyst, hydrogen gas decomposes into protons and electrons. Protons pass through a proton exchange membrane to the cathode, while electrons generate current through an external circuit, producing electrical energy. At the cathode, protons and electrons react with oxygen in the air to produce water. The electrical energy generated can directly power a forklift or be stored in a battery.

[0031] In addition, since the fuel cell stack generates heat during operation, a cooler is also provided in the fuel cell stack to cool it down in order to keep it working better at the optimal operating temperature.

[0032] See Figure 1 This embodiment discloses a thermal management system for a solid-state hydrogen storage fuel cell, including a heater installed in the hydrogen storage system to preheat the hydrogen storage tank, and a cooler installed on the outer periphery of the fuel cell stack 2 to cool it. The outlet of the cooler is connected to a heating device 22 and a radiator 23 respectively through a three-way reversing valve 21. The outlets of the heating device 22 and the radiator 23 are both connected to the inlet of the cooler, thereby forming a stack cooling circuit and a stack preheating circuit. A water-to-water heat exchanger 14 is connected in series between the inlet and outlet of the heater. The water-to-water heat exchanger 14 has two independent pipelines. One pipeline is connected to the inlet and outlet of the heater at both ends, and the other pipeline is connected to the inlet and outlet of the cooler at both ends, thereby forming a hydrogen storage heat exchange circuit.

[0033] That is, the preheating circuit of the fuel cell stack is formed by the outlet of the cooler, the three-way reversing valve 21, the heating device 22, and the inlet of the cooler. The fuel cell stack cooling circuit consists of the cooler outlet, three-way reversing valve 21, radiator 23, and cooler inlet. The preheating circuit consists of the heater inlet - water-to-water heat exchanger 14 - heater outlet, and the heat transfer circuit consists of the outlet of heating device 22 or radiator 23 - water-to-water heat exchanger 14 - three-way reversing valve 21 - heating device 22 or radiator 23. The preheating circuit and the heat transfer circuit together constitute the hydrogen storage heat exchange circuit.

[0034] When preheating is required, the heating device 22 is turned on. A portion of the circulating liquid enters the fuel cell stack 2 through the stack preheating circuit for preheating, while the other portion of the circulating liquid enters the hydrogen storage system 1 through the hydrogen storage heat exchange circuit for preheating.

[0035] When preheating is not required, both the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit are shut down.

[0036] When the temperature of the fuel cell stack 2 rises above its normal operating temperature range after working for a period of time, the stack cooling circuit is opened to cool the circulating liquid in the cooler through the radiator 23.

[0037] In this embodiment, the heater and cooler can be containers with multiple tubes arranged in a circular pattern. A carrier flows within these containers and exchanges heat with external heating or cooling devices to achieve preheating or cooling. The carrier is a circulating liquid such as water or coolant, and the specific type can be selected according to actual conditions.

[0038] In this field, the circulating fluid used in the fuel cell stack preheating circuit, fuel cell stack cooling circuit and heat transfer circuit connected to the cooler in the fuel cell stack is the fuel cell stack coolant, and the circulating fluid in the preheating circuit connected to the hydrogen storage system can be water or conventional coolant.

[0039] In order to replenish the circulating fluid in a timely manner, a heating replenishment tank 12 is connected to the pipeline between the first water pump 13 and the outlet of the heater, and a cooling replenishment tank 27 is connected to the pipeline in the radiator 23.

[0040] Specifically, the outlets of the heating device 22 and the radiator 23 are connected to the inlet of the cooler through the second water pump 25, which enables the circulating liquid to flow quickly; a filter 24 is connected in series between the radiator 23 and the second water pump 25 to filter out impurities from the circulating liquid.

[0041] A deionizer 26 is connected between the outlet of the second water pump 25 and the inlet of the three-way reversing valve 21. This deionizer is used to remove ions from the circulating fluid to prevent affecting the lifespan of the fuel cell stack.

[0042] In order to monitor the temperature of each circulation loop in real time, a second temperature detector 28 for detecting liquid temperature is installed at the outlet of the cooler, and a first temperature detector 11 for detecting liquid temperature is installed at the inlet of the heater.

[0043] A first water pump 13 is connected in series between the water inlet of the heater and the water-to-water heat exchanger 14. A one-way valve 15 is connected between the water-to-water heat exchanger 14 and the outlet of the cooler, so that the hot water before entering the cooler enters the water-to-water heat exchanger 14 for heat exchange and then merges with the water at the outlet of the cooler.

[0044] The water-to-water heat exchanger 14 in this application is an existing product. It is used for heat exchange between two circulating liquids (water or coolant) at different temperatures, and these two circulating liquids are independent and do not mix, transferring heat from the high-temperature circulating liquid to the low-temperature circulating liquid. Specifically, it has two separate pipes inside. One pipe is connected to the inlet and outlet of the heater at both ends, and the other pipe is connected to the inlet and outlet of the cooler at both ends, thus forming a hydrogen storage heat exchange loop. The heat in the heat transfer loop is transferred to the preheating loop to preheat the hydrogen storage system.

[0045] Its circuit control principle is as follows Figure 2 As shown, the system includes a vehicle control unit (VCU), a fuel cell control unit (FCU), instruments, and a power battery on the forklift. The power battery is connected to the vehicle control unit via a BMS. The vehicle control unit is connected to the fuel cell control unit and the instruments. The fuel cell control unit controls the operation or shutdown of the stack cooling circuit, the stack preheating circuit, and the hydrogen storage heat exchange circuit. The fuel cell stack 2 is electrically connected to the vehicle power supply and the power battery via a DC-DC converter to provide operating power. The power battery is charged by connecting to an external power source via a charging gun.

[0046] Specifically, the output of the fuel cell controller is connected to the three-way reversing valve 21, the electric fan in the radiator 23, the filter 24, the heating device 22, the first water pump 13, and the second water pump 25, respectively, and drives them to operate or stop. Meanwhile, the input of the fuel cell controller is connected to the first temperature sensor 11 and the second temperature sensor 28. The power battery is preferably a lithium battery, which is controlled by the BMS.

[0047] In this embodiment, the three-way reversing valve 21, heating device 22, radiator 23, and filter 24 are all known commercially available products.

[0048] Specifically, the heating device 22 is preferably a PTC, and the radiator 23 contains an electric fan. The cooling effect of the fuel cell cooling circuit is controlled by controlling the switching or speed of the electric fan. The three-way reversing valve 21 has three ports, one inlet and two outlets. By controlling the position of its valve core, the inlet is connected to one of the outlets, realizing the switching of the circulating fluid.

[0049] In a specific embodiment, each loop operates as follows: 1. Fuel Cell Stack Cooling Circuit: During normal operation, the fuel cell stack generates a large amount of heat, including excessively high temperatures in the circulating fluid of the cooler. At this time, the FCU controls the connection between ports B1 and B3 of the three-way directional valve 21. The cooler's outlet T1 is connected to the radiator 23 via the three-way directional valve 21. The radiator is connected to the filter 24, and the filter 24 is connected to the cooler's inlet P1 via the second water pump 25, forming the fuel cell stack cooling circuit. Its main purpose is to dissipate the heat generated during fuel cell stack operation, keeping the stack at its optimal operating temperature of 60-80℃.

[0050] A second temperature sensor 28 is installed at the outlet T1 of the cooler to detect the temperature in real time and feed it back to the FCU.

[0051] Meanwhile, the coolant replenishment tank 27 is connected to the circulation pipe in the radiator 23 to achieve real-time replenishment of circulating fluid. The coolant replenishment tank 27 is equipped with a liquid level sensor, which will send a signal to the FCU to alarm when the liquid level is low.

[0052] 2. Fuel Cell Stack Preheating Circuit: Under low-temperature conditions, the fuel cell stack 2 needs to be preheated before it can operate normally. At this time, the FCU controls the connection between ports B1 and B2 of the three-way reversing valve 21; the cooler's outlet T1 is connected to the heating device 22 (such as a PTC) through the three-way reversing valve 21, and the heating device 22 is connected to the cooler's inlet P1 through the second water pump 25, forming the fuel cell stack preheating circuit. Its main purpose is to preheat the fuel cell stack under low-temperature conditions before starting it, avoiding damage caused by cold starts at low temperatures and affecting its service life. 3. The hydrogen storage heat exchange circuit includes a preheating circuit and a heat transfer circuit, as detailed below: ① Preheating circuit: Part of the circulating liquid at the outlet of the second water pump 25 enters the inlet P1 of the cooler, and the other part enters the water-to-water heat exchanger 14, that is, it enters its separate internal pipe from port A1, then exits from port A2, and then enters the inlet B1 of the three-way reversing valve 21, forming a preheating circuit for the fuel cell stack water. Its main purpose is to introduce the heat in the fuel cell stack circuit into the water-to-water heat exchanger 14 for heat exchange.

[0053] ② Heat transfer circuit: After the first water pump 13 is turned on, the circulating liquid in the other pipeline of the water-water heat exchanger 14 is preheated and then introduced into the inlet P2 of the heater in the hydrogen storage system. Its outlet T2 is connected to the first water pump 13, and then enters the water-water heat exchanger from port A3 to form a heat transfer circuit.

[0054] A first temperature sensor 11 is installed at the outlet T2 to detect the temperature of the circulating fluid and send the data back to the FCU. A heating replenishment tank 12 is connected to the pipeline between the outlet T2 and the first water pump 13 for real-time replenishment of the circulating fluid. The heating replenishment tank is equipped with a sensor to detect its liquid level; when the liquid level in the heating replenishment tank 12 is low, it will send a notification to the FCU.

[0055] The coolants used in the fuel cell stack cooling, preheating, and heat transfer circuits require deionization because contamination of the coolant can affect the stack's lifespan and increase maintenance and replacement costs. However, the preheating circuit in the hydrogen storage system can use ordinary coolant or water, which is easily contaminated due to frequent disassembly and reassembly. Therefore, this application uses a water-to-water heat exchanger 14 to isolate the heat transfer circuit for preheating the hydrogen storage system 2 from the preheating circuit connected to the fuel cell stack. This ensures that the circulating fluids in the two circuits are independent and isolated, preventing mutual interference. Furthermore, filters and deionizers are installed in the fuel cell stack cooling and preheating circuits to ensure the cleanliness of the circulating fluids and improve the lifespan of the fuel cell stack.

[0056] The working process of the thermal management system in this embodiment is as follows: When the ambient temperature is too low (e.g., below 0℃), the fuel cell stack preheating circuit needs to be activated for preheating, and the hydrogen storage heat exchange circuit is started simultaneously. This involves opening ports B1 and B2 of the three-way reversing valve 21 in the fuel cell stack preheating circuit, while simultaneously starting the heating device 22, the second water pump 25, and the first water pump 13. The circulating liquid in the fuel cell stack preheating circuit, after being heated by the heating device 22, enters the cooler through port P1 and then re-enters the heating device through port T1 for further heating; the other part enters the water-to-water heat exchanger 14, passing through ports A1 and A2, then through the check valve 15, and finally back to port B1 of the three-way reversing valve 21, forming a circulation. Simultaneously, heat exchange occurs in the water-to-water heat exchanger 14, and the first water pump 13 introduces the heat-exchanged circulating liquid from the water-to-water heat exchanger 14 into the hydrogen storage system for preheating.

[0057] When the liquid temperature detected by the first temperature sensor 11 at the heater outlet reaches the normal operating temperature of the hydrogen storage system, the first water pump 13 is turned off, which means the hydrogen storage heat exchange circuit is shut down.

[0058] When the liquid temperature at the cooler outlet reaches the lower limit of the normal operating temperature of the fuel cell stack, the heating device 22 is turned off, and the circulating liquid circulates without being heated.

[0059] When the liquid temperature at the cooler outlet reaches the upper limit of the normal operating temperature of the fuel cell stack, the heating device 22 is shut off. Simultaneously, the three-way reversing valve 21 is opened at ports B1 and B3, allowing the circulating liquid to enter the radiator 23 from port B3 for heat dissipation. Then, it passes through the filter 24 and the second water pump 25 before entering the cooler to form a cooling cycle. This ensures the circulating liquid temperature remains within the optimal operating temperature range, improving the efficiency of the fuel cell stack.

[0060] After working for a period of time, the deionizer 26 is started, so that a portion of the circulating liquid from the second water pump 25 enters the deionizer 26 for deionization, and then it is recirculated.

[0061] Example 2: A control method for the thermal management system of a solid-state hydrogen storage fuel cell includes the following steps: S1. Set the temperature A when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to idle, the temperature B when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to operate normally, and the temperature C when the fuel cell stack operates normally. For example, A can be set to 0℃, which means that when the temperature of the circulating liquid in the hydrogen storage system reaches 0℃, its internal hydrogen release equilibrium pressure is ≥0.8MPa, which can meet the requirements of the vehicle idling operation. Since this parameter varies depending on the hydrogen storage material, this parameter is set as a configurable parameter and can be modified according to the performance of different hydrogen storage materials.

[0062] B is set to 10℃, meaning that when the temperature of the circulating liquid in the hydrogen storage system reaches 10℃, its internal hydrogen release equilibrium pressure is ≥1MPa, which can meet the requirements of the vehicle operating at full power. Since this parameter varies depending on the hydrogen storage material, it is set as a configurable parameter and can be modified according to the performance of different hydrogen storage materials.

[0063] C represents 0-80℃, meaning the normal operating temperature of the fuel cell stack is 0-80℃, i.e., Cmin=0℃ and Cmax=80℃. When the real-time temperature of the fuel cell stack is less than 0℃, the stack preheating circuit needs to be activated for preheating; when the real-time temperature of the fuel cell stack is greater than 80℃, the stack cooling circuit needs to be activated for cooling.

[0064] S2. Collect the liquid temperature t1 in the hydrogen storage heat exchange circuit and the liquid temperature t2 at the fuel cell stack outlet, respectively, and t1≤t2; When t2 < Cmin and t1 < A, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit work simultaneously, preheating the fuel cell stack while exchanging heat with the hydrogen storage system, causing the temperatures of both the fuel cell stack and the hydrogen storage system to rise. When t2>Cmin and A≤t1<B, the fuel cell stack preheating circuit and hydrogen storage heat exchange circuit continue to work, causing the temperature of the fuel cell stack and hydrogen storage system to continue to rise. S3. When t1≥B, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit continue to work until t1≥B+5. Then, the heating device in the fuel cell stack preheating circuit is turned off, and the liquid temperature in the hydrogen storage heat exchange circuit will gradually decrease. When t1≤B, the heating device in the fuel cell stack preheating circuit restarts. This cycle continues to ensure that B≤t1≤B+5. When the fuel cell stack is started at this time, the output power of the fuel cell stack is 100%. S4. After the fuel cell stack is started, when t2≥Cmax, the stack cooling circuit is turned on to cool it. At the same time, some of the hot water in the cooling circuit enters the hydrogen storage heat exchange circuit to preheat the hydrogen storage system. When t2 < Cmax, shut down the fuel cell stack cooling water circuit.

[0065] Specifically, in step S2, when t2>Cmin and A≤t1<B, the heating device in the fuel cell stack preheating circuit is turned off. At this time, the fuel cell stack is allowed to start. During the process of t1 rising from A to B, the output power of the fuel cell stack is linearly positively correlated with t1, that is, the output power of the fuel cell stack increases linearly from 10% to 100% of the rated power. When the fuel cell stack is working, the heat it generates continuously heats the hydrogen storage system through the hydrogen storage heat exchange circuit.

[0066] The output power of the fuel cell stack is automatically adjusted by the real-time liquid temperature t1 of the hydrogen storage system. Specifically, the output power of the fuel cell stack increases linearly from 10% to 100% of the rated power as the temperature t1 increases (from A to B). Correspondingly, the vehicle control unit (VCU) responds synchronously to provide the forklift with the corresponding kinetic energy, enabling full-power drive capability from idle start to full-load hill climbing. In step s3, when t1≥B, the heating device in the fuel cell stack preheating circuit is turned off. At this time, the fuel cell stack is allowed to start, and the fuel cell stack can output 100% power.

[0067] In another embodiment, the power supply for the fuel cell preheating circuit and the hydrogen storage heat exchange circuit is provided by the power battery, and their startup is predicated on the triggering of the power battery charging signal, i.e.: When a charging signal is detected that the power battery is connected to an external power source, the stack preheating circuit and the hydrogen storage heat exchange circuit are simultaneously activated. When the power battery is not being charged, the fuel cell preheating circuit and the hydrogen storage heat exchange circuit are simultaneously shut down.

[0068] Specifically, the power supply for the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit is provided by the power battery. Specifically, the battery management system (BMS) monitors the charging status of the power battery in real time and transmits it to the fuel cell controller (FCU) through the vehicle controller (VCU). The fuel cell controller (FCU) then controls the operation or shutdown of components such as heating devices and water pumps in the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit, thereby controlling the opening or closing of the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit.

[0069] The activation of the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit is controlled by the charging signal of the power battery: Only when the VCU receives a charging signal indicating that the power battery has established an electrical connection with an external power source (such as a charging pile) can the two circuits be opened simultaneously to enter the preheating / heat exchange working mode. When the power battery is not in a charging state (i.e., the charging signal disappears), both circuits are immediately shut down, maintaining a non-working state.

[0070] Example 3: A forklift is equipped with a thermal management system for a solid-state hydrogen storage fuel cell as described in Example 1, and executes the control method as described in the example. The specific example of this forklift is described below: In this embodiment, when the solid-state hydrogen fuel cell forklift is started at low temperature, its hydrogen storage system needs to be preheated before it can supply hydrogen normally, so that the whole vehicle can enter the best working state as quickly as possible.

[0071] (1) After the vehicle is powered on, the FCU controls the first temperature sensor 11 installed in the hydrogen storage heat exchange circuit in the thermal management system to detect the liquid temperature t1, and the second temperature sensor 28 installed at the fuel cell outlet to detect its liquid temperature t2, and t1≤t2; and transmits it to the FCU.

[0072] First, set the temperature A when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to idle, the temperature B when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to operate normally, and the temperature C when the fuel cell stack operates normally. In this embodiment, A is set to 0℃, meaning that when the liquid temperature of the solid hydrogen storage system is 0℃, its internal hydrogen release equilibrium pressure is ≥0.8MPa, which can meet the needs of the vehicle idling operation; B is set to 10℃, meaning that when the liquid temperature of the circulating liquid in the hydrogen storage system reaches 10℃, its internal hydrogen release equilibrium pressure is ≥1MPa, which can meet the needs of the vehicle full-power operation; C is 0-80℃, meaning Cmin=0℃ and Cmax=80℃. When the real-time liquid temperature of the fuel cell stack is detected to be less than 0℃, the stack preheating circuit needs to be turned on for preheating; when the real-time liquid temperature of the fuel cell stack is detected to be greater than 80℃, the stack cooling circuit needs to be turned on for cooling.

[0073] 1) When t2 < Cmin and t1 < A, the FCU sends a preheating status request to the VCU and displays it simultaneously on the instrument panel. The instrument panel pops up a preheating interface, displaying the real-time liquid temperature of the hydrogen storage system and a text reminder (Please plug in the charging gun and turn on the preheating mode), guiding the user to perform preheating-related operations. In this state, the fuel cell stack is not allowed to start, and the output power of the vehicle's traction motor and pump motor is limited to 0. This is to prevent the fuel cell system from failing to start and affecting its lifespan, and to avoid the risk of the vehicle moving while plugged in for charging.

[0074] The detailed control strategies for different user operation states and preheating modes are as follows: (1) When the power battery is charged by only the charging gun and the preheating mode is not turned on, the FCU controls the thermal management system to not work (i.e. the hydrogen storage system does not turn on the preheating function), the BMS controls the power battery to charge, and the preheating interface on the instrument displays: real-time liquid temperature of hydrogen storage system + text reminder (please turn on the preheating mode), and continues to guide the user to perform preheating-related operations. (2) When only the preheating mode is turned on and the charging gun is not plugged in, the FCU controls the thermal management system to not work (i.e. the hydrogen storage system does not turn on the preheating function) to avoid the power battery being discharged too much. The BMS controls the power battery to perform the preheating and discharging strategy in the normal state without plugging in the charging gun. The preheating interface on the instrument displays: real-time liquid temperature of the hydrogen storage system + text reminder (please plug in the charging gun to preheat), and continues to guide the user to perform preheating-related operations. (3) When the user turns on the preheating mode and plugs in the charging gun, the FCU controls the thermal management system to turn on the preheating function, the three-way reversing valve 21 opens the fuel cell preheating circuit, the heating device 22, the first water pump 11 and the second water pump 28 start working at the same time, and other electronic devices do not work. At this time, the fuel cell preheating circuit and the hydrogen storage heat exchange circuit work normally, the hydrogen storage system starts to preheat, and the BMS controls the power battery to perform the preheating and charging strategy according to the normal plug-in state. The preheating interface on the instrument displays: real-time liquid temperature of hydrogen storage system + text reminder (preheating, please do not interrupt), guiding the user not to interrupt the preheating; 2) The temperatures of the fuel cell stack and hydrogen storage system both rise. When t2>Cmin and A≤t1<B, the fuel cell stack preheating circuit and hydrogen storage heat exchange circuit continue to work, causing the temperatures of the fuel cell stack and hydrogen storage system to continue to rise. At this point, the fuel cell stack can be started. During the process of t1 rising from A to B, the output power of the fuel cell stack is linearly positively correlated with t1. At this time, the FCU controls the thermal management system to continue preheating, meaning that the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit are working normally. The BMS controls the power battery to execute the preheating and charging strategy according to the conventional plug-in state. The preheating interface on the instrument panel displays: real-time liquid temperature of the hydrogen storage system + text reminder (preheating, the charging gun can be disconnected for limited power use). In this state, the fuel cell system is allowed to idle, the vehicle can be used at low power, and the hydrogen storage system is preheated by the residual heat of the fuel cell stack, allowing it to slowly enter the optimal working state. If the preheating mode is turned off at this time, and only the charging gun is plugged in, the FCU controls the thermal management system to turn off the preheating function. That is, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit stop working, the solid hydrogen storage system stops preheating, and the BMS controls the power battery to perform the preheating and charging strategy according to the normal plug-in state. The instrument control preheating interface displays: real-time liquid temperature of hydrogen storage system + text reminder (preheating stopped, the charging gun can be unplugged and the power limited), prompting the user that preheating has stopped and guiding the user to unplug the charging gun and use it with limited power. If the user wants to continue preheating, he can open the preheating mode option on the instrument preheating interface and perform the above operation. If the charging gun is unplugged at this time, it indicates that the preheating mode is actively exited. The instrument panel exits the preheating interface and returns to the main interface. The FCU controls the thermal management system to turn off the preheating function, that is, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit stop working, and the solid hydrogen storage system stops preheating. In this state, the fuel cell is allowed to idle, and the vehicle can use limited power. The hydrogen storage system is preheated by the residual heat of the fuel cell stack, so that it slowly enters the optimal working state. If the vehicle is left unattended for an extended period, the liquid temperature of the hydrogen storage system will drop. When the FCU detects that t1 < A, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit will continue to operate.

[0075] 3) When t1 ≥ B in the hydrogen storage heat exchange circuit, the FCU controls the thermal management system to continue preheating until t1 ≥ B + 5. At this point, all components in the thermal management system, except for the heating device (PTC), operate normally. When the liquid temperature in the hydrogen storage heat exchange circuit drops, i.e., t1 ≤ B, the PTC restarts. This cycle repeats to ensure the liquid temperature remains at B ≤ t1 ≤ B + 5, entering the heat preservation mode. The preheating interface on the instrument displays: real-time liquid temperature of the hydrogen storage system + text reminder (preheating complete, please unplug the charging gun for use), indicating to the user that preheating is complete and guiding the user to unplug the charging gun for use. (1) When the preheating mode is turned off and only the charging gun is plugged in, the FCU controls the thermal management system to turn off the preheating function, that is, the stack preheating circuit and B≤t1≤B+5 stop working, the hydrogen storage system stops preheating, and the BMS controls the power battery to perform the preheating and charging strategy according to the normal plugging state. The preheating interface on the instrument displays: real-time liquid temperature of hydrogen storage system + text reminder (preheating stopped, the charging gun can be unplugged for use), prompting the user that preheating has stopped and guiding the user to unplug the charging gun for use; (2) When the charging gun is unplugged, it indicates that the preheating mode is actively exited. The instrument exits the preheating interface and returns to the main interface. The FCU controls the thermal management system to turn off the preheating function, that is, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit stop working, and the hydrogen storage system stops preheating. In this state, the liquid temperature in the hydrogen storage heat exchange circuit is at the optimal working state, the fuel cell stack operates at full power, and the vehicle can be used normally. If the vehicle is left unattended for an extended period, the liquid temperature in the hydrogen storage heat exchange circuit will drop. When the FCU detects that t1 < A, the fuel cell preheating circuit and the hydrogen storage heat exchange circuit will continue to operate.

[0076] 4) After the fuel cell stack is started, when t2≥Cmax, the stack cooling circuit is turned on to cool it. At the same time, some of the hot water in the cooling circuit enters the hydrogen storage heat exchange circuit to preheat the hydrogen storage system. When t2 < Cmax, shut down the fuel cell stack cooling water circuit.

[0077] To exit preheating mode, if both the charging gun and the preheating mode switch are not simultaneously met, exit preheating mode immediately. Alternatively, exit preheating mode by turning off the key. After powering on, retest and follow the steps above.

[0078] Because the circulating fluid in the thermal management system loop has a large capacity, the power consumption required for preheating at low temperatures is significant. The capacity of the typically equipped power battery is insufficient. To prevent excessive power consumption during preheating from causing battery depletion, especially in cases of cell undervoltage and starvation, the preheating function must be performed while the battery is plugged into a charging gun. If the power battery capacity is sufficient to meet the preheating power consumption requirements, plugging into a charging gun can be disregarded; simply having the user turn on the preheating mode switch is sufficient.

[0079] The present invention and its embodiments have been described above illustratively. This description is not restrictive and is merely one embodiment of the present invention, and is not actually limited thereto. Therefore, if those skilled in the art are inspired by this description and design similar structures and embodiments without departing from the spirit of the present invention, such designs should fall within the protection scope of the present invention.

Claims

1. A thermal management system for a solid-state hydrogen storage fuel cell, comprising a heater disposed within the hydrogen storage system to preheat the hydrogen storage tank, and a cooler disposed on the outer periphery of the fuel cell stack (2) to cool it, characterized in that, The outlet of the cooler is connected to the heating device (22) and the radiator (23) respectively through a three-way reversing valve (21). The outlets of the heating device (22) and the radiator (23) are connected to the inlet of the cooler, thereby forming a fuel cell stack cooling circuit and a fuel cell stack preheating circuit. A water-to-water heat exchanger (14) is connected in series between the inlet and outlet of the heater. The water-to-water heat exchanger (14) has two independent pipelines. One pipeline is connected to the inlet and outlet of the heater at both ends, and the other pipeline is connected to the inlet and outlet of the cooler at both ends, thereby forming a hydrogen storage heat exchange circuit.

2. The thermal management system for a solid-state hydrogen storage fuel cell according to claim 1, characterized in that, The outlets of the heating device (22) and the radiator (23) are connected to the inlet of the cooler through the second water pump (25); a filter (24) is connected in series between the radiator (23) and the second water pump (25).

3. The thermal management system for a solid-state hydrogen storage fuel cell according to claim 2, characterized in that, A deionizer (26) is connected between the outlet of the second water pump (25) and the inlet of the three-way reversing valve (21).

4. The thermal management system for a solid-state hydrogen storage fuel cell according to claim 1, characterized in that, The cooler outlet and the heater inlet are both equipped with temperature detectors for detecting liquid temperature.

5. The thermal management system for a solid-state hydrogen storage fuel cell according to claim 1, characterized in that, A first water pump (13) is connected in series between the water inlet of the heater and the water-to-water heat exchanger (14). A one-way valve (15) is connected between the water-to-water heat exchanger (14) and the outlet of the cooler, so that the hot water before entering the cooler enters the water-to-water heat exchanger (14) for heat exchange and then merges with the water at the outlet of the cooler.

6. The thermal management system for a solid-state hydrogen storage fuel cell according to claim 1, characterized in that, It also includes a vehicle controller, fuel cell controller, instrumentation, and power battery on the forklift. The power battery is connected to the vehicle controller via a BMS. The vehicle controller is connected to the fuel cell controller and instrumentation. The fuel cell controller controls the operation or shutdown of the stack cooling circuit, stack preheating circuit, and hydrogen storage heat exchange circuit. The fuel cell stack (2) is electrically connected to the vehicle power supply and the power battery respectively through a DC-DC converter to provide working power.

7. A forklift, characterized in that, It is equipped with a thermal management system for a solid hydrogen storage fuel cell as described in any one of claims 1-6.

8. The control method for the thermal management system of a solid-state hydrogen storage fuel cell as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Set the temperature A when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to idle, the temperature B when the hydrogen storage system meets the minimum hydrogen release amount for the vehicle to operate normally, and the temperature C when the fuel cell stack operates normally. S2. Collect the liquid temperature t1 in the hydrogen storage heat exchange circuit and the liquid temperature t2 at the fuel cell stack outlet, respectively, and t1≤t2; When t2 < Cmin and t1 < A, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit work simultaneously, preheating the fuel cell stack while exchanging heat with the hydrogen storage system, causing the temperatures of both the fuel cell stack and the hydrogen storage system to rise. When t2>Cmin and A≤t1<B, the fuel cell stack preheating circuit and hydrogen storage heat exchange circuit continue to work, causing the temperature of the fuel cell stack and hydrogen storage system to continue to rise. S3. When t1≥B, the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit continue to work until t1≥B+5. Then, the heating device in the fuel cell stack preheating circuit is turned off, and the liquid temperature in the hydrogen storage heat exchange circuit will gradually decrease. When t1≤B, the heating device in the fuel cell stack preheating circuit restarts. This cycle continues to ensure that B≤t1≤B+5. When the fuel cell stack is started at this time, the output power of the fuel cell stack is 100%. S4. After the fuel cell stack is started, when t2≥Cmax, the stack cooling circuit is turned on to cool it. At the same time, some of the hot water in the cooling circuit enters the hydrogen storage heat exchange circuit to preheat the hydrogen storage system. When t2 < Cmax, shut down the fuel cell stack cooling water circuit.

9. The control method according to claim 8, characterized in that, In step S2, when t2>Cmin and A≤t1<B, the heating device in the fuel cell stack preheating circuit is turned off. At this time, the fuel cell stack is allowed to start. During the process of t1 rising from A to B, the output power of the fuel cell stack is linearly positively correlated with t1, that is, the output power of the fuel cell stack increases linearly from 10% to 100% of the rated power. When the fuel cell stack is working, the heat it generates continuously heats the hydrogen storage system through the hydrogen storage heat exchange circuit. In step s3, when t1≥B, the heating device in the fuel cell stack preheating circuit is turned off. At this time, the fuel cell stack is allowed to start, and the fuel cell stack can output 100% power.

10. The control method according to claim 8, characterized in that, The power supply for the fuel cell stack preheating circuit and the hydrogen storage heat exchange circuit is provided by the power battery, and their startup is predicated on the power battery charging signal. When a charging signal is detected that the power battery is connected to an external power source, the stack preheating circuit and the hydrogen storage heat exchange circuit are simultaneously activated. When the power battery is not being charged, the fuel cell preheating circuit and the hydrogen storage heat exchange circuit are simultaneously shut down.

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