Cold start system and method for solid hydrogen storage gas-electric forklift

Abstract

The invention discloses a cold start system and method for a solid-state hydrogen storage gas-electric forklift, and belongs to the technical field of solid-state hydrogen storage gas-electric forklifts.The system comprises a hydraulic oil tank, a heat exchanger, a power battery and a solid-state hydrogen storage mechanism; the hydraulic oil tank is connected with a heating medium inlet and a heating medium outlet of the heat exchanger, and a refrigerant outlet of the heat exchanger is connected with a first heating pipe and a second heating pipe. The first heating pipe flows through the power battery and is connected with a refrigerant inlet of the heat exchanger through a first return pipe, and a first electromagnetic valve is arranged on the first heating pipe; and the second heating pipe flows through the solid hydrogen storage mechanism and is connected with a refrigerant inlet of the heat exchanger through a second return pipe, and a second electromagnetic valve is arranged on the second heating pipe. The power battery and the solid hydrogen storage mechanism are heated through heat generated by the hydraulic system, charging of the power battery at low temperature is achieved, and the solid hydrogen storage mechanism releases hydrogen to complete cold start of the fuel cell system.

Description

Technical Field

[0001] The present invention belongs to the technical field of solid-state hydrogen storage fuel-electric forklifts, and in particular relates to a cold start system and method for a solid-state hydrogen storage fuel-electric forklift. Background Art

[0002] As a new type of clean and pollution-free energy, hydrogen has been receiving continuous attention in recent years. Solid-state hydrogen storage has the advantages of large hydrogen storage capacity, simple storage conditions and long service life. The characteristics of metal alloys are large storage capacity and safe use process, but stable hydrides require higher temperatures to undergo dehydrogenation (dehydrogenation) reactions. Metal hydrides release hydrogen when heated. This process is called desorption. Hydrogen atoms (H) move from the metal to the surface of the material and combine into hydrogen molecules (H2), thereby achieving the flow of hydrogen.

[0003] In the prior art, solid-state hydrogen storage fuel-electric forklifts have difficulty starting in low-temperature environments, mainly including the two major problems that the power battery cannot be charged in low-temperature conditions and the solid-state hydrogen storage mechanism cannot release hydrogen in low temperatures. If the cold start of a solid-state hydrogen storage fuel-electric forklift is performed by means of resistance wire heating, a large amount of energy will be consumed.

[0004] The invention patent application with publication number CN117841784A discloses a solid-state hydrogen storage fuel cell forklift system and its thermal management method. The system includes a fuel cell system, a power battery component, and a hydrogen storage and buffer component. The method includes calculating the heat released by the fuel cell system and the power battery, as well as the heat absorbed by the hydrogen storage material and the heat absorption energy storage material, and guiding the selection of the cooling fan or the selection and dosage of the heat absorption energy storage material according to the heat conservation relationship. The capacity stored in the heat absorption energy storage material helps the system to start quickly, and the fuel cell is heated quickly by heating the solid-state hydrogen storage device and the power battery. However, the heat generation of the battery in the low temperature environment (hundred watts) of the invention application cannot support the heat absorption (kilowatts) in the process of solid-state hydrogen storage releasing hydrogen, so the fuel cell cannot be guaranteed to start under low temperature conditions. In addition, the battery pack BMS strategy in the low temperature state will limit the charging of the battery pack. If the heat generated by the battery pack is given to the fuel cell system startup and the solid-state hydrogen storage heat absorption and hydrogen release through the heat exchanger, the power of the fuel cell cannot be effectively loaded after startup, thereby causing the startup failure of the fuel cell system.

[0005] The invention patent application with publication number CN116968503A discloses a thermal management system for electric forklifts, including: a battery cooling loop, a battery heating loop, a cab cooling loop, a cab heating loop, a conduction control unit, and a thermal management control module; the thermal management control module controls the operation of the conduction control unit and each loop according to the temperature data of the battery in the electric forklift and / or the thermal management request input from the outside; the invention satisfies the thermal management requirements of the battery and the cab at the same time by providing a set of thermal management systems. However, the invention application is for the thermal management of the whole vehicle of the electric forklift. By heat exchanging the heat dissipation system of the battery pack with the air conditioner in the cab, the heat generated by the battery pack can be effectively utilized during the heating process. However, since there is no solid-state hydrogen storage system in the system, the cold start problem of the fuel cell cannot be solved. In addition, during the heating process, since only the application of heat is increased, the heat dissipation requirements of the battery pack during high-rate discharge cannot be supported. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a solid-state hydrogen storage fuel-electric forklift cold start system and method, which heats the power battery and the solid-state hydrogen storage mechanism through the heat generated by the hydraulic system itself, thereby realizing the charging of the power battery at low temperatures and the release of hydrogen by the solid-state hydrogen storage mechanism to complete the cold start of the fuel cell system.

[0007] The present invention provides the following technical solutions: In a first aspect, a solid-state hydrogen storage fuel-electric forklift cold start system is provided, comprising a hydraulic oil tank, a heat exchanger, a power battery and a solid-state hydrogen storage mechanism; The hydraulic oil tank is respectively connected to the heat medium inlet and the heat medium outlet of the heat exchanger, and the cold medium outlet of the heat exchanger is respectively connected to the first heating pipe and the second heating pipe; The first heating tube flows through the power battery and is connected to the refrigerant inlet of the heat exchanger through a first return pipe, and a first solenoid valve is provided on the first heating tube; The second heating tube flows through the solid hydrogen storage mechanism and is connected to the refrigerant inlet of the heat exchanger through a second reflux tube. A second solenoid valve is provided on the second heating tube.

[0008] Furthermore, it also includes a thermostat, the refrigerant outlet of the heat exchanger is connected to a heating main pipe, the heating main pipe is connected to the inlet of the thermostat, and the outlet of the thermostat is respectively connected to the first heating pipe and the second heating pipe.

[0009] Furthermore, the first solenoid valve is arranged at a portion of the first heating tube between the thermostat and the power battery, and the second solenoid valve is arranged at a portion of the second heating tube between the thermostat and the solid-state hydrogen storage mechanism.

[0010] Furthermore, the first return pipe and the second return pipe are both connected to a return main pipe, and the return main pipe is connected to a refrigerant inlet of the heat exchanger; and the refrigerant flowing through the heat exchanger is antifreeze.

[0011] In a second aspect, a solid-state hydrogen storage fuel-electric forklift cold start method is provided, which is applied to the solid-state hydrogen storage fuel-electric forklift cold start system in the first aspect, comprising: In low temperature conditions, start the forklift and ensure normal operation of the forklift through whole machine energy control. During the operation of the forklift, the temperature of the hydraulic oil in the hydraulic oil tank rises, and the heat of the hydraulic oil heats the refrigerant flowing through the heat exchanger; The first solenoid valve is opened, and the heated refrigerant flows through the power battery through the first heating tube, so that the power battery is heated to a preset temperature. Then the second solenoid valve is opened, and the heated refrigerant flows through the solid hydrogen storage mechanism through the second heating tube, so that the solid hydrogen storage mechanism is heated and releases hydrogen, thereby realizing a cold start of the fuel cell system. After the fuel cell system is operating normally, close the second solenoid valve and use the fuel cell system to supply heat to the solid-state hydrogen storage mechanism. At the same time, by adjusting the opening of the first solenoid valve, the power battery is maintained at a preset temperature to complete the cold start of the solid-state hydrogen storage fuel-electric forklift.

[0012] Furthermore, the method for controlling the energy of the whole machine includes: Calculate the heat dissipation of the hydraulic oil tank, the heat required to increase the temperature of the hydraulic oil tank and the hydraulic oil, and the heat required for the solid hydrogen storage mechanism to release hydrogen, and further calculate the total heat consumed by the hydraulic system; Calculate the heat generated by the hydraulic pump based on the total heat consumed by the hydraulic system, and calculate the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift based on the heat generated by the hydraulic pump; The total power of the forklift during low-temperature operation is calculated according to the power utilization rate of the hydraulic pump during the forklift's low-temperature operation, and the energy control strategy of the whole machine is calculated according to the total power of the forklift during low-temperature operation.

[0013] Furthermore, the method for calculating the total heat consumed by the hydraulic system includes: Calculate the heat dissipation of the hydraulic oil tank, the formula is as follows: ; In the formula, is the heat dissipation of the hydraulic oil tank, K i is the heat dissipation coefficient, A i is the heat dissipation area of ​​the hydraulic oil tank, is the temperature difference between the hydraulic oil and the hydraulic oil tank and the environment; Calculate the heat required to increase the temperature of the hydraulic oil tank and hydraulic oil, the formula is as follows: ; In the formula, The heat required to increase the temperature of the hydraulic oil tank and hydraulic oil, c 1 is the specific heat of the hydraulic oil tank material, c 2 is the specific heat of hydraulic oil, m 1 is the mass of the hydraulic oil tank, m 2 is the quality of hydraulic oil; The formula for calculating the heat required for the solid-state hydrogen storage mechanism to release hydrogen is as follows: ; In the formula, The heat required to release hydrogen from the solid-state hydrogen storage mechanism, n A is the molar amount of metal hydride, is the standard heat of reaction of metal hydrides releasing hydrogen, is the reaction coefficient of metal hydride, is the product enthalpy, is the enthalpy of the reactants, n i is the molar amount of the product, H i is the enthalpy of the product, n j is the molar amount of the reactants, H j is the enthalpy of the reactants; Calculate the total heat consumed by the hydraulic system using the following formula: ; In the formula, is the total heat consumed by the hydraulic system, is the heat loss coefficient of the heat exchanger, and Q is the heat demand for heating the power battery.

[0014] Furthermore, the method of calculating the heat generated by the hydraulic pump according to the total heat consumed by the hydraulic system, and calculating the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift according to the heat generated by the hydraulic pump includes: According to the law of conservation of energy, the total heat generated by the hydraulic system per unit time is H Equal to the total heat consumed by the hydraulic system , and the total heat generated by the hydraulic system H The calculation formula is as follows: ; In the formula, H 1 is the heat generation of the hydraulic pump, H 2 is the heat generated by the travel motor, H 3 is the heat generated by the total potential energy loss when the gantry descends,H 4 is the heat generated by the resistance loss of pipelines and hydraulic components; During the actual low-temperature operation of the forklift, H 2. H 3. H 4 is negligible, then H1≈H; The formula for calculating the power utilization of the hydraulic pump during low-temperature operation of the forklift is as follows: ; In the formula, is the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift. is the efficiency loss of the hydraulic pump, P P is the rated pressure of the hydraulic pump, Q P is the rated flow of the hydraulic pump.

[0015] Furthermore, the method of calculating the total power of the forklift during low-temperature operation according to the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift, and calculating the energy control strategy of the whole machine according to the total power of the forklift during low-temperature operation includes: Calculate the total power of the forklift in low temperature operation, the formula is as follows: ; In the formula, P is the total power of the forklift at low temperature operation, is the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift. P 1 is the full power output of the hydraulic pump, P 2 is the power requirement of the travel motor; The energy control strategy of the whole machine is calculated as follows: ; Where: SOC is the proportion of the remaining power of the power battery, t The working time of the power battery, Q 0 is the total power of the power battery.

[0016] Furthermore, after the power battery is heated to a preset temperature and the second solenoid valve is opened, more heated refrigerant is allowed to flow through the solid hydrogen storage mechanism through the second heating tube by adjusting the opening of the thermostat. The purpose of adding a thermostat is that the heat demand of the solid hydrogen storage mechanism is much greater than the heat demand of the power battery, and by adjusting the opening of the thermostat, the flow of the heated refrigerant flowing to the solid hydrogen storage mechanism and the power battery can be distributed.

[0017] Furthermore, when the forklift is started and operated at normal temperature, the first solenoid valve and the second solenoid valve are closed.

[0018] Compared with the prior art, the present invention has the following beneficial effects: (1) The present invention uses the heat of the hydraulic oil generated during the normal operation of the forklift at low temperature to transfer the heat to the power battery and the solid-state hydrogen storage mechanism through a heat exchanger. On the one hand, the power battery is heated, solving the problem that the power battery cannot be charged at low temperature. On the other hand, the solid-state hydrogen storage mechanism is heated to complete the release of hydrogen, thereby achieving a cold start of the fuel cell system. (2) The present invention controls the forklift truck by cold start system design and whole machine energy control and other starting methods. The forklift truck can be cold started by the heat generated by the hydraulic system itself without relying on additional heating equipment, thereby ensuring maximum energy efficiency, simplifying the system structure design, and saving component costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 2 is a schematic diagram of the structure of a cold start system for a solid-state hydrogen storage fuel-electric forklift according to an embodiment of the present invention; Figure 2 It is a schematic diagram of the cold start process of a solid-state hydrogen storage fuel-electric forklift in an embodiment of the present invention; The markings in the figure are: 1. Hydraulic oil tank; 2. Heat exchanger; 201. Heat medium inlet; 202. Heat medium outlet; 203. Refrigerant outlet; 204. Refrigerant inlet; 3. Power battery; 4. Solid-state hydrogen storage mechanism; 5. First solenoid valve; 6. Second solenoid valve; 7. Thermostat; 8. Heating main pipe; 9. First heating pipe; 10. Second heating pipe; 11. First return pipe; 12. Second return pipe; 13. Return main pipe; 14. Forklift. DETAILED DESCRIPTION

[0020] The present invention will be further described below in conjunction with the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and cannot be used to limit the protection scope of the present invention.

[0021] Example 1

[0022] like Figure 1 As shown, this embodiment provides a solid-state hydrogen storage fuel-electric forklift cold start system, including a hydraulic oil tank 1, a heat exchanger 2, a thermostat 7, a power battery 3 and a solid-state hydrogen storage mechanism 4.

[0023] The hydraulic oil tank 1 is respectively connected to the heat medium inlet 201 and the heat medium outlet 202 of the heat exchanger 2. The refrigerant outlet 203 of the heat exchanger 2 is respectively connected to the first heating pipe 9 and the second heating pipe 10; specifically, the refrigerant outlet 203 of the heat exchanger 2 is connected to the heating main pipe 8, the heating main pipe 8 is connected to the inlet of the thermostat 7, and the outlet of the thermostat 7 is respectively connected to the first heating pipe 9 and the second heating pipe 10.

[0024] The first heating tube 9 flows through the power battery 3 and is connected to the refrigerant inlet 204 of the heat exchanger 2 through the first return tube 11, and the second heating tube 10 flows through the solid hydrogen storage mechanism 4 and is connected to the refrigerant inlet 204 of the heat exchanger 2 through the second return tube 12. Specifically, the first return tube 11 and the second return tube 12 are both connected to the return main pipe 13, and the return main pipe 13 is connected to the refrigerant inlet 204 of the heat exchanger 2; the refrigerant flowing through the heat exchanger 2 is antifreeze.

[0025] The first heating tube 9 is provided with a first solenoid valve 5, and the first solenoid valve 5 is provided at the portion of the first heating tube 9 between the thermostat 7 and the power battery 3. The second heating tube 10 is provided with a second solenoid valve 6, and the second solenoid valve 6 is provided at the portion of the second heating tube 10 between the thermostat 7 and the solid hydrogen storage mechanism 4.

[0026] Example 2 like Figure 1 and Figure 2 As shown, this embodiment provides a solid-state hydrogen storage fuel-electric forklift cold start method, which is applied to the solid-state hydrogen storage fuel-electric forklift cold start system described in Example 1, and the steps are as follows: Step 1: Under low temperature conditions, start the forklift 14 and ensure the normal operation of the forklift 14 through whole machine energy control. During the operation of the forklift 14, the temperature of the hydraulic oil in the hydraulic oil tank 1 rises, and the heat of the hydraulic oil is used to heat the refrigerant flowing through the heat exchanger 2.

[0027] Step 2, open the first solenoid valve 5, and the heated refrigerant flows through the power battery 3 through the heating main pipe 8 and the first heating pipe 9, so that the power battery 3 is heated to a preset temperature of 5~30°C. In this embodiment, the preset temperature is set to 20°C.

[0028] Step 3, open the second solenoid valve 6, and at the same time, adjust the opening of the thermostat 7 to allow more heated refrigerant to flow through the solid hydrogen storage mechanism 4 through the second heating tube 10, so that the solid hydrogen storage mechanism 4 heats up and releases hydrogen, thereby achieving a cold start of the fuel cell system.

[0029] The purpose of adding the thermostat 7 is that the heat demand of the solid hydrogen storage mechanism 4 is much greater than the heat demand of the power battery 3. By adjusting the opening of the thermostat 7, the refrigerant flow to the solid hydrogen storage mechanism 4 and the power battery 3 can be distributed.

[0030] Step 4: After the fuel cell system is operating normally, close the second solenoid valve 6, and supply heat to the solid-state hydrogen storage mechanism 4 through the fuel cell system. At the same time, adjust the opening of the first solenoid valve 5 to adjust the flow of the heated refrigerant flowing through the power battery 3, so that the power battery 3 is maintained at a preset temperature of 20°C to complete the cold start of the solid-state hydrogen storage fuel-electric forklift.

[0031] Under normal temperature, when the forklift 14 is started and operated, the solid-state hydrogen storage mechanism 4 and the power battery 3 are started or operated normally. At this time, the first solenoid valve 5 and the second solenoid valve 6 are closed to ensure that the solid-state hydrogen storage mechanism 4 and the power battery 3 will not have over-temperature problems.

[0032] The whole machine energy control in step 1 can ensure that the forklift can start and run normally under low temperature conditions, and the heat generated by the forklift hydraulic oil is sufficient to meet the heat required for solid hydrogen storage and dehydrogenation and the power battery temperature rise. The specific method steps of the whole machine energy control are as follows: Step 1.1, calculate the heat dissipation of the hydraulic oil tank, the formula is as follows: ; In the formula, is the heat dissipation of the hydraulic oil tank, K i is the heat dissipation coefficient, A i is the heat dissipation area of ​​the hydraulic oil tank, It is the temperature difference between hydraulic oil, hydraulic oil tank and the environment.

[0033] Step 1.2: Calculate the heat required to increase the temperature of the hydraulic oil tank and hydraulic oil. The formula is as follows: ; In the formula, The heat required to increase the temperature of the hydraulic oil tank and hydraulic oil, c 1 is the specific heat of the hydraulic oil tank material, c 2 is the specific heat of hydraulic oil, m 1 is the mass of the hydraulic oil tank, m 2 is the quality of hydraulic oil.

[0034] Step 1.3: Calculate the heat required for the solid-state hydrogen storage mechanism to release hydrogen. The formula is as follows: ; In the formula, The heat required to release hydrogen from the solid-state hydrogen storage mechanism, n A is the molar amount of metal hydride, is the standard heat of reaction of metal hydrides releasing hydrogen, is the reaction coefficient of metal hydride, is the product enthalpy, is the enthalpy of the reactants, n i is the molar amount of the product, H i is the enthalpy of the product, n j is the molar amount of the reactants, Hj is the enthalpy of the reactants.

[0035] Step 1.4: Calculate the total heat consumed by the hydraulic system using the following formula: ; In the formula, is the total heat consumed by the hydraulic system, is the heat loss coefficient of the heat exchanger, and Q is the heat demand for heating the power battery.

[0036] Step 1.5. Calculate the heat generated by the hydraulic pump based on the total heat consumed by the hydraulic system.

[0037] According to the law of conservation of energy, the total heat generated by the hydraulic system per unit time is H Equal to the total heat consumed by the hydraulic system , and the total heat generated by the hydraulic system H The calculation formula is as follows: ; In the formula, H 1 is the heat generation of the hydraulic pump, H 2 is the heat generated by the travel motor, H 3 is the heat generated by the total potential energy loss when the gantry descends, H 4 is the heat generated by the resistance loss of pipelines and hydraulic components; During the actual low-temperature operation of the forklift, H 2. H 3. H 4 can be ignored, then H1≈H.

[0038] Step 1.6: Calculate the power utilization of the hydraulic pump during low-temperature operation of the forklift according to the heat generated by the hydraulic pump. The formula is as follows: ; In the formula, is the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift. is the efficiency loss of the hydraulic pump, P P is the rated pressure of the hydraulic pump, Q P is the rated flow of the hydraulic pump.

[0039] Step 1.7: Calculate the total power of the forklift during low-temperature operation based on the power utilization rate of the hydraulic pump during the forklift's low-temperature operation. The formula is as follows: ; In the formula, P is the total power of the forklift at low temperature operation, is the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift.P 1 is the full power output of the hydraulic pump, P 2 is the power requirement of the travel motor.

[0040] Step 1.8: Calculate the energy control strategy of the whole machine based on the total power of the forklift running at low temperature. The formula is as follows: ; Where: SOC is the proportion of the remaining power of the power battery, t The working time of the power battery, Q 0 is the total power of the power battery.

[0041] In summary, the present invention controls the starting methods such as cold start system design and whole machine energy control, and uses the heat of the hydraulic oil generated during the early normal operation of the forklift under low temperature conditions to transfer the heat to the power battery and the solid-state hydrogen storage mechanism through a heat exchanger. On the one hand, the power battery is heated, solving the problem that the power battery cannot be charged at low temperatures. On the other hand, the solid-state hydrogen storage mechanism is heated to complete the release of hydrogen, thereby achieving a cold start of the fuel cell system. The cold start process ensures the maximization of energy efficiency without relying on additional heating equipment. The system structure is simple in design, saving component costs.

[0042] Those skilled in the art will appreciate that the embodiments of the present application may be provided as methods, systems, or computer program products. Therefore, the present application may take the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware. Moreover, the present application may take the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program codes.

[0043] The present application is described with reference to the flowcharts and / or block diagrams of the methods, devices (systems), and computer program products according to the embodiments of the present application. It should be understood that each process and / or box in the flowchart and / or block diagram, as well as the combination of the processes and / or boxes in the flowchart and / or block diagram, can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing device to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing device generate instructions for implementing the processes in the flowchart and / or block diagram. Figure 1 A process or multiple processes and / or boxes Figure 1 A device that provides the functions specified in a block or multiple blocks.

[0044] These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing device to operate in a specific manner, so that the instructions stored in the computer-readable memory produce an article of manufacture comprising an instruction device, which implements the process Figure 1 A process or multiple processes and / or boxes Figure 1 A function specified in one or more boxes.

[0045] These computer program instructions can also be loaded onto a computer or other programmable data processing device so that a series of operating steps are executed on the computer or other programmable device to produce a computer-implemented process, thereby providing instructions for implementing the process. Figure 1 A process or multiple processes and / or boxes Figure 1 The steps for the functions specified in one or more boxes.

[0046] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A solid-state hydrogen storage fuel-electric forklift cold start system, characterized in that: Includes hydraulic oil tank, heat exchanger, power battery and solid hydrogen storage mechanism; The hydraulic oil tank is respectively connected to the heat medium inlet and the heat medium outlet of the heat exchanger, and the cold medium outlet of the heat exchanger is respectively connected to the first heating pipe and the second heating pipe; The first heating tube flows through the power battery and is connected to the refrigerant inlet of the heat exchanger through a first return pipe, and a first solenoid valve is provided on the first heating tube; The second heating tube flows through the solid hydrogen storage mechanism and is connected to the refrigerant inlet of the heat exchanger through a second reflux tube. A second solenoid valve is provided on the second heating tube.

2. The solid-state hydrogen storage fuel-electric forklift cold start system according to claim 1 is characterized in that: It also includes a thermostat, wherein the refrigerant outlet of the heat exchanger is connected to a heating main pipe, the heating main pipe is connected to the inlet of the thermostat, and the outlet of the thermostat is respectively connected to the first heating pipe and the second heating pipe.

3. The solid-state hydrogen storage fuel-electric forklift cold start system according to claim 2 is characterized in that: The first solenoid valve is arranged at a portion of the first heating tube between the thermostat and the power battery, and the second solenoid valve is arranged at a portion of the second heating tube between the thermostat and the solid-state hydrogen storage mechanism.

4. The solid-state hydrogen storage fuel-electric forklift cold start system according to claim 1 is characterized in that: The first return pipe and the second return pipe are both connected to a return main pipe, and the return main pipe is connected to a refrigerant inlet of the heat exchanger; the refrigerant flowing through the heat exchanger is antifreeze.

5. A cold start method for a solid hydrogen storage fuel-electric forklift, characterized in that: The solid-state hydrogen storage fuel-electric forklift cold start system applied to any one of claims 1 to 4 comprises: In low temperature conditions, start the forklift and ensure normal operation of the forklift through whole machine energy control. During the operation of the forklift, the temperature of the hydraulic oil in the hydraulic oil tank rises, and the heat of the hydraulic oil heats the refrigerant flowing through the heat exchanger; The first solenoid valve is opened, and the heated refrigerant flows through the power battery through the first heating tube, so that the power battery is heated to a preset temperature. Then the second solenoid valve is opened, and the heated refrigerant flows through the solid hydrogen storage mechanism through the second heating tube, so that the solid hydrogen storage mechanism is heated and releases hydrogen, thereby realizing a cold start of the fuel cell system. After the fuel cell system is operating normally, close the second solenoid valve and use the fuel cell system to supply heat to the solid-state hydrogen storage mechanism. At the same time, by adjusting the opening of the first solenoid valve, the power battery is maintained at a preset temperature to complete the cold start of the solid-state hydrogen storage fuel-electric forklift.

6. The cold start method of a solid hydrogen storage fuel-electric forklift according to claim 5, characterized in that: The method for whole machine energy control comprises: Calculate the heat dissipation of the hydraulic oil tank, the heat required to increase the temperature of the hydraulic oil tank and the hydraulic oil, and the heat required for the solid hydrogen storage mechanism to release hydrogen, and further calculate the total heat consumed by the hydraulic system; Calculate the heat generated by the hydraulic pump based on the total heat consumed by the hydraulic system, and calculate the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift based on the heat generated by the hydraulic pump; The total power of the forklift during low-temperature operation is calculated according to the power utilization rate of the hydraulic pump during the forklift's low-temperature operation, and the energy control strategy of the whole machine is calculated according to the total power of the forklift during low-temperature operation.

7. The cold start method of a solid hydrogen storage fuel-electric forklift according to claim 6, characterized in that: The method for calculating the total heat consumed by the hydraulic system includes: Calculate the heat dissipation of the hydraulic oil tank, the formula is as follows: ； In the formula, is the heat dissipation of the hydraulic oil tank, K i is the heat dissipation coefficient, A i is the heat dissipation area of ​​the hydraulic oil tank, is the temperature difference between the hydraulic oil and the hydraulic oil tank and the environment; Calculate the heat required to increase the temperature of the hydraulic oil tank and hydraulic oil, the formula is as follows: ； In the formula, The heat required to increase the temperature of the hydraulic oil tank and hydraulic oil, c 1 is the specific heat of the hydraulic oil tank material, c 2 is the specific heat of hydraulic oil, m 1 is the mass of the hydraulic oil tank, m 2 is the quality of hydraulic oil; The formula for calculating the heat required for the solid-state hydrogen storage mechanism to release hydrogen is as follows: ； In the formula, The heat required to release hydrogen from the solid-state hydrogen storage mechanism, n A is the molar amount of metal hydride, is the standard heat of reaction of metal hydrides releasing hydrogen, is the reaction coefficient of metal hydride, is the product enthalpy, is the enthalpy of the reactants, n i is the molar amount of the product, H i is the enthalpy of the product, n j is the molar amount of the reactants, H j is the enthalpy of the reactants; Calculate the total heat consumed by the hydraulic system using the following formula: ； In the formula, is the total heat consumed by the hydraulic system, is the heat loss coefficient of the heat exchanger, and Q is the heat demand for heating the power battery.

8. The cold start method of a solid hydrogen storage fuel-electric forklift according to claim 6, characterized in that: The method for calculating the heat generation of the hydraulic pump according to the total heat consumed by the hydraulic system, and calculating the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift according to the heat generation of the hydraulic pump comprises: According to the law of conservation of energy, the total heat generated by the hydraulic system per unit time is H Equal to the total heat consumed by the hydraulic system , and the total heat generated by the hydraulic system H The calculation formula is as follows: ； In the formula, H 1 is the heat generation of the hydraulic pump, H 2 is the heat generated by the travel motor, H 3 is the heat generated by the total potential energy loss when the gantry descends, H 4 is the heat generated by the resistance loss of pipelines and hydraulic components; During the actual low-temperature operation of the forklift, H 2. H 3. H 4 is negligible, then H1≈H; The formula for calculating the power utilization of the hydraulic pump during low-temperature operation of the forklift is as follows: ； In the formula, is the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift. is the efficiency loss of the hydraulic pump, P P is the rated pressure of the hydraulic pump, Q P is the rated flow of the hydraulic pump.

9. The cold start method of a solid hydrogen storage fuel-electric forklift according to claim 6, characterized in that: The method of calculating the total power of the forklift at low temperature according to the power utilization rate of the hydraulic pump during the forklift's low temperature operation, and calculating the whole machine energy control strategy according to the total power of the forklift at low temperature, includes: Calculate the total power of the forklift in low temperature operation, the formula is as follows: ； In the formula, P is the total power of the forklift at low temperature operation, is the power utilization rate of the hydraulic pump during the low-temperature operation of the forklift. P 1 is the full power output of the hydraulic pump, P 2 is the power requirement of the travel motor; The energy control strategy of the whole machine is calculated as follows: ； Where: SOC is the proportion of the remaining power of the power battery, t The working time of the power battery, Q 0 is the total power of the power battery.

10. The cold start method of a solid hydrogen storage fuel-electric forklift according to claim 5, characterized in that: After the power battery is heated to a preset temperature and the second solenoid valve is opened, more heated refrigerant is allowed to flow through the solid hydrogen storage mechanism through the second heating tube by adjusting the opening of the thermostat.

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