A liquid hydrogen precooling system and control method thereof

Abstract

A liquid hydrogen precooling system comprises a cold side flow path, a hot side flow path, a heat exchanger, a reheater and a collecting component. Liquid hydrogen is introduced into the input end of the cold side flow path, and gaseous hydrogen is introduced into the input end of the hot side flow path. The cold side flow path and the hot side flow path are respectively connected to the heat exchanger. Heat is exchanged between the cold side flow path and the hot side flow path through the heat exchanger. The reheater and the collecting component are respectively connected to the cold side flow path. The reheater is arranged between the collecting component and the heat exchanger. The vaporized liquid hydrogen is further heated by the reheater so that the hydrogen entering the collecting component meets the hydrogenation standard of the hydrogenator. A compressor is provided at the output end of the collecting component. The reheated hydrogen is collected by the collecting component. The hydrogen in the collecting component is transported to hydrogenation or other equipment using hydrogen through the compressor. The collecting component can store the reheated hydrogen and can be used as a buffer to buffer the hydrogen entering the compressor so that the pressure of the hydrogen entering the compressor is more stable.

Description

Technical Field

[0001] The present invention belongs to the technical field of liquid hydrogen precooling systems, and in particular relates to a liquid hydrogen precooling system and a control method thereof. Background Art

[0002] Conventional hydrogen refueling stations use long tube trailers as hydrogen sources and high-pressure hydrogen coolers for heat exchange and cooling. However, as the gas source pressure decreases, the hydrogen flow rate gradually decreases, causing the hydrogen outlet temperature to fluctuate. In addition, as the external environmental conditions and the pressure and temperature of hydrogen change, the hydrogen outlet temperature will fluctuate greatly, so that the output hydrogen cannot meet the needs of back-end users. Currently, the hydrogen precooling systems on the market mainly use liquid nitrogen to precool hydrogen. Liquid nitrogen and hydrogen are vaporized after heat exchange. Some precooling systems liquefy nitrogen through external equipment to achieve the purpose of recycling liquid nitrogen. However, this type of equipment for recycling liquid nitrogen consumes a lot of energy, and the cost of equipment use increases. Some precooling systems directly discharge the vaporized nitrogen into the air, resulting in a waste of nitrogen resources, which also increases the cost of equipment use. Summary of the invention

[0003] In view of the above shortcomings, the technical problem to be solved by the present invention is to provide a liquid hydrogen precooling system and a control method thereof, in which hydrogen is precooled by liquid hydrogen, and the vaporized liquid hydrogen can be utilized, thereby reducing the use cost of the precooling equipment.

[0004] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0005] A liquid hydrogen precooling system comprises a cold side flow path, a hot side flow path, a heat exchanger, a recuperator and a collecting assembly, wherein the cold side flow path and the hot side flow path are respectively connected to the heat exchanger, and heat is exchanged between the cold side flow path and the hot side flow path through the heat exchanger, the recuperator and the collecting assembly are respectively connected to the cold side flow path, the recuperator is arranged between the collecting assembly and the heat exchanger, and a compressor is provided at the output end of the collecting assembly.

[0006] As a preferred solution of the present invention, a venting pipeline and a collecting pipeline are provided at the output end of the cold side flow path, the collecting assembly is connected to the collecting pipeline, and a venting valve is provided on the venting pipeline.

[0007] As a preferred solution of the present invention, the collection assembly includes a hydrogen storage tank and a storage tank pressure transmitter, and the storage tank pressure transmitter is connected to the vent valve electrical signal.

[0008] As a preferred solution of the present invention, a cold side inlet pressure transmitter, a cold side inlet temperature transmitter and a cold side outlet temperature transmitter are provided on the cold side flow path, the cold side inlet pressure transmitter and the cold side inlet temperature transmitter are arranged at the front end of the heat exchanger, and the cold side outlet temperature transmitter is arranged at the rear end of the heat exchanger.

[0009] As a preferred solution of the present invention, a hot side inlet pressure transmitter, a hot side inlet temperature transmitter and a hot side outlet temperature transmitter are provided on the hot side flow path, the hot side inlet pressure transmitter and the hot side inlet temperature transmitter are arranged at the front end of the heat exchanger, and the hot side outlet temperature transmitter is arranged at the rear end of the heat exchanger.

[0010] As a preferred solution of the present invention, a cold side inlet regulating valve is provided at the input end of the cold side flow path, and the hot side outlet temperature transmitter is electrically connected to the cold side inlet regulating valve.

[0011] As a preferred solution of the present invention, a hot side inlet regulating valve is provided at the input end of the hot side flow path, and the cold side inlet regulating valve is electrically signal-connected to the hot side inlet regulating valve.

[0012] As a preferred solution of the present invention, a three-way valve is provided at the output end of the hot side flow path, and the three-way valve is connected to the collection component to guide the hydrogen in the hot side flow path to the collection component, and the hot side outlet temperature transmitter is electrically connected to the three-way valve signal.

[0013] The above-mentioned control method of a liquid hydrogen precooling system comprises the following steps:

[0014] S1, when the temperature of the hot side flow path is greater than the set value A, the hydrogen is directed to the collection component, and at the same time, the liquid hydrogen flow rate of the cold side flow path is increased until the temperature of the hot side flow path drops to the set value A, the hot side flow path is disconnected from the collection component, and the hydrogen is output through the output end of the hot side flow path;

[0015] S2, when the temperature of the hot side flow path is greater than the set value A+X (X is the temperature alarm deviation value, X>0), the system alarms and jumps back to step S3.1 for processing. If the liquid hydrogen flow rate of the cold side flow path has reached the maximum, the flow rate of the hot side flow path is reduced until the temperature of the hot side flow path drops to the set value A;

[0016] S3, when the temperature of the hot side flow path is lower than the set value B (B≤0), the liquid hydrogen flow rate of the cold side flow path is reduced until the temperature of the hot side flow path reaches the set value B;

[0017] S4, when the temperature of the hot side flow path is lower than the set value BX (X is the temperature alarm deviation value, X>0), the system alarms and jumps back to step S3.3 for processing. If the liquid hydrogen flow rate of the cold side flow path has reached the minimum, the flow rate of the hot side flow path is increased until the temperature of the hot side flow path drops to the set value B;

[0018] S5, when the pressure of the collecting assembly is ≤C (C≥0), all the hydrogen in the cold side flow path is directed into the collecting assembly; when the pressure of the collecting assembly is >C, the hydrogen in the cold side flow path is vented until the pressure of the collecting assembly is ≤C;

[0019] S6, when the pressure of the collection component is greater than C+P (P is the pressure alarm deviation value, P>0), the system alarms and jumps back to step S3.5 for processing; if the pressure of the collection component is greater than C+P1 (P1 is the pressure alarm critical deviation value, P1>P>0), the system alarms and prompts to manually open the collection component to vent.

[0020] As a preferred solution of the present invention, in steps S1 and S3, the calculation method of the liquid hydrogen flow rate and liquid hydrogen pressure at the input end of the cold side flow path is as follows:

[0021] S1.1, the enthalpy of hydrogen at the input end of the hot side flow path is h1(p1,T1), the enthalpy of hydrogen at the output end of the hot side flow path is set according to the demand, h2(p2,T2), and the heat exchange required for the hot side flow path is calculated, where p1 is the hydrogen pressure at the input end of the hot side flow path, T1 is the hydrogen temperature at the input end of the hot side flow path, p2 is the hydrogen pressure at the output end of the hot side flow path, and T2 is the hydrogen temperature at the output end of the hot side flow path;

[0022] S1.2, according to the heat exchange required by the hot side flow path and the thermal efficiency of the heat exchanger, obtain the enthalpy value of the liquid hydrogen at the input end of the cold side flow path, and obtain the liquid hydrogen flow rate and liquid hydrogen pressure at the input end corresponding to the required enthalpy value of the liquid hydrogen at the input end of the cold side flow path.

[0023] The beneficial effect of the present invention is that the gaseous hydrogen in the hydrogen refueling station is precooled by liquid hydrogen to ensure that the hydrogen precooled by the precooling system meets the hydrogen refueling standard of the hydrogen refueling station. At the same time, the precooling system can utilize the vaporized hydrogen in the hydrogen refueling station, which can reduce the energy consumption of the precooling system on the one hand and utilize the refrigerant on the other hand, thereby reducing the use cost of the precooling system. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the liquid hydrogen precooling system.

[0025] Figure 2 is the graph of enthalpy.

[0026] Figure numerals: hot side inlet regulating valve 1; hot side inlet pressure transmitter 2; hot side inlet temperature transmitter 3; hot side outlet temperature transmitter 4; vacuum cold box 5; cold side inlet regulating valve 6; cold side inlet pressure transmitter 7; cold side inlet temperature transmitter 8; cold side outlet temperature transmitter 9; vent valve 10; tank pressure transmitter 11; hot side flow path 12; collecting pipeline 13; cold side flow path 14; vent pipeline 15; heat exchanger 16; reheater 17; hydrogen storage tank 18; compressor 19; three-way valve 20. DETAILED DESCRIPTION

[0027] The present invention will be further described below in conjunction with the accompanying drawings.

[0028] like Figure 1As shown, a liquid hydrogen precooling system includes a cold side flow path 14, a hot side flow path 12, a heat exchanger 16, a recuperator 17 and a collecting component. Liquid hydrogen is introduced into the input end of the cold side flow path 14, and gaseous hydrogen is introduced into the input end of the hot side flow path 12. The cold side flow path 14 and the hot side flow path 12 are respectively connected to the heat exchanger 16. The cold side flow path 14 and the hot side flow path 12 are heat exchanged through the heat exchanger 16. The recuperator 17 and the collecting component are respectively connected to the cold side flow path 14. The recuperator 17 is arranged between the collecting component and the heat exchanger 16. 17 further heats the vaporized liquid hydrogen so that the hydrogen entering the collecting component meets the hydrogenation standard of the hydrogenator. A compressor 19 is provided at the output end of the collecting component. The reheated hydrogen is collected by the collecting component, and the hydrogen in the collecting component is transported to the hydrogenation or other equipment using hydrogen through the compressor 19. The collecting component can store the reheated hydrogen and can serve as a buffer to buffer the hydrogen entering the compressor 19, thereby making the pressure of the hydrogen entering the compressor 19 more stable.

[0029] As a preferred embodiment, the heat exchanger 16 is placed in the vacuum cold box 5, and the vacuum cold box 5 is evacuated to reduce the loss of cold. The material of the heat exchanger 16 is austenitic stainless steel 316L, and the nickel content of the stainless steel material 316L is not less than 12%. The pressure of gaseous hydrogen is relatively high, and the pressure resistance of the heat exchanger is improved by reducing the total width of the gaseous hydrogen channel and the inner diameter of the head.

[0030] A vent pipeline 15 and a collecting pipeline 13 are provided at the output end of the cold side flow path 14. The collecting component is connected to the collecting pipeline 13. The cold side flow path 14 and the collecting component are connected through the collecting pipeline 13, and the hydrogen at the output end of the cold side flow path 14 is guided into the collecting component. A vent valve 10 is provided on the vent pipeline 15, and the hydrogen in the system is discharged to the outside of the system through the vent pipeline 15 through the vent valve 10.

[0031] The collecting component includes a hydrogen storage tank 18 and a tank pressure transmitter 11. The hydrogen storage tank 18 is used to store or buffer hydrogen. The tank pressure transmitter 11 is installed on the hydrogen storage tank 18. The tank pressure transmitter 11 is electrically connected to the vent valve 10. The opening of the vent valve 10 is controlled by the pressure in the tank pressure transmitter 11.

[0032] A cold side inlet pressure transmitter 7, a cold side inlet temperature transmitter 8 and a cold side outlet temperature transmitter 9 are provided on the cold side flow path 14. The cold side inlet pressure transmitter 7 and the cold side inlet temperature transmitter 8 are arranged at the front end of the heat exchanger 16, and are used to detect the pressure and temperature of liquid hydrogen at the input end of the cold side flow path 14. The cold side outlet temperature transmitter 9 is arranged at the rear end of the heat exchanger 16, and is used to detect the temperature of hydrogen after the liquid hydrogen is vaporized by heat exchange. Preferably, the cold side outlet temperature transmitter 9 is connected to the recuperator 17, and is used to control the power used by the recuperator 17, so as to ensure that the temperature of the hydrogen input to the hydrogen storage tank 18 reaches the standard of the hydrogenator.

[0033] A hot side inlet pressure transmitter 2, a hot side inlet temperature transmitter 3 and a hot side outlet temperature transmitter 4 are provided on the hot side flow path 12. The hot side inlet pressure transmitter 2 and the hot side inlet temperature transmitter 3 are arranged at the front end of the heat exchanger 16, and are used to detect the temperature and pressure of the hydrogen at the input end of the hot side flow path 12, so as to facilitate the calculation of the enthalpy value of the hydrogen at the input end of the hot side flow path 12. The hot side outlet temperature transmitter 4 is arranged at the rear end of the heat exchanger 16, and the hydrogen temperature at the output end of the hot side flow path 12 is controlled by the hot side outlet temperature transmitter 4, so that the hydrogen temperature at the output end reaches the standard of the hydrogenator.

[0034] A cold side inlet regulating valve 6 is provided at the input end of the cold side flow path 14, and the flow of the cold side flow path 14 is controlled by controlling the opening of the cold side inlet regulating valve 6. The hot side outlet temperature transmitter 4 is electrically connected to the cold side inlet regulating valve 6, and the operation of the cold side inlet regulating valve 6 is controlled according to the hydrogen temperature at the output end of the hot side flow path 12.

[0035] A hot side inlet regulating valve 1 is provided at the input end of the hot side flow path 12, and the flow of the hot side flow path 12 is controlled by controlling the opening of the hot side inlet regulating valve 1. The cold side inlet regulating valve 6 is electrically connected to the hot side inlet regulating valve 1, and the operation of the hot side inlet regulating valve 1 is controlled by the cold side inlet regulating valve 6.

[0036] A three-way valve 20 is provided at the output end of the hot side flow path 12, and the three-way valve 20 is connected to the hydrogen storage tank 18. When the hydrogen in the hot side flow path 12 does not meet the standard of the hydrogenator, the hydrogen in the hot side flow path 12 is diverted to the collecting component, so that the hydrogen that does not meet the standard of the hydrogenator is mixed with the hydrogen vaporized from liquid hydrogen, thereby diluting the hydrogen that does not meet the standard of the hydrogenator, so that the hydrogen diluted by the hydrogen storage tank 18 meets the standard of the hydrogenator, and the standard hydrogen of the hydrogenator is used conveniently. The hot side outlet temperature transmitter 4 is electrically connected to the three-way valve 20.

[0037] During the operation of the liquid hydrogen precooling system, the hydrogen temperature of the hot side flow path 12 will change dynamically. To ensure that the hydrogen temperature of the hot side flow path 12 meets the standard of the hydrogenator, the control method of the liquid hydrogen precooling system includes the following steps:

[0038] S1, when the hot side outlet temperature transmitter 4 of the hot side flow path 12 detects that the hydrogen temperature is greater than the set value A (A≤0), the three-way valve 20 is controlled to guide the hydrogen to the hydrogen storage tank 18. At the same time, the hot side outlet temperature transmitter 4 sends an electrical signal to the cold side inlet regulating valve 6, so that the opening of the cold side inlet regulating valve 6 becomes larger, the liquid hydrogen flow rate of the cold side flow path 14 is increased, and the liquid hydrogen pressure at the input end of the cold side flow path 14 is increased until the temperature of the hot side flow path 12 drops to the set value A, and the three-way valve 20 is controlled to disconnect the hot side flow path 12 from the hydrogen storage tank 18, so that the hydrogen is output through the output end of the hot side flow path 12;

[0039] S2, when the hot side outlet temperature transmitter 4 detects that the hydrogen temperature is greater than the set value A+X (X is the temperature alarm deviation value, X≥0), the system alarms and jumps back to step S3.1 for processing. If the liquid hydrogen flow rate of the cold side flow path 14 has reached the maximum, that is, the cold side inlet regulating valve 6 is at the maximum opening, and the liquid hydrogen flow rate at the input end of the cold side flow path 14 is at the maximum state, the cold side inlet regulating valve 6 sends a control signal to the hot side inlet regulating valve 1, and the opening of the hot side inlet regulating valve 1 is reduced, reducing the flow rate of the hot side flow path 12 until the temperature of the hot side flow path 12 drops to the set value A;

[0040] S3, when the hot side outlet temperature transmitter 4 of the hot side flow path 12 detects that the hydrogen temperature is less than the set value B (B≤0), the cold side inlet regulating valve 6 is opened less, the liquid hydrogen flow of the cold side flow path 14 is reduced, and the liquid hydrogen pressure at the input end is reduced accordingly, until the temperature of the hot side flow path 12 drops to the set value B;

[0041] S4, when the hot side outlet temperature transmitter 4 of the hot side flow path 12 detects that the hydrogen temperature is less than the set value BX (X is the temperature alarm deviation value, X≥0), the system alarms and jumps back to step S3.3 for processing. If the liquid hydrogen flow rate of the cold side flow path 14 has reached the minimum, that is, the opening of the cold side inlet regulating valve 6 is at the minimum, and the liquid hydrogen flow rate at the input end of the cold side flow path 14 is at the minimum state, the cold side inlet regulating valve 6 sends a control signal to the hot side inlet regulating valve 1, and the opening of the hot side inlet regulating valve 1 increases, increasing the flow rate of the hot side flow path 12 until the temperature of the hot side flow path 12 drops to the set value B;

[0042] S5, when the pressure of the hydrogen storage tank 18 of the collection component is ≤C (C≥0), the vent valve 10 is closed, and all the hydrogen in the cold side flow path 14 is directed to the hydrogen storage tank 18; when the pressure of the hydrogen storage tank 18 of the collection component is >C, the hydrogen in the cold side flow path 14 is vented, and at the same time, the hydrogen in the hydrogen storage tank 18 is discharged through the vent valve 10 side or the compressor 19 side until the pressure of the collection component is ≤C;

[0043] S6, when the pressure of the hydrogen storage tank 18 of the collection component is greater than C+P (P is the pressure alarm deviation value, P≥0), the system alarms and jumps back to step S3.5 for processing; if the pressure of the collection component is greater than C+P1 (P1 is the pressure alarm critical deviation value, P1>P≥0), the system alarms, and if the vent valve 10 has reached the maximum opening, it prompts to manually open the collection component to vent.

[0044] In this embodiment, X is the temperature alarm deviation value, that is, the temperature fluctuates between A+X and BX and is adjusted by the liquid hydrogen precooling system. When the temperature is not within the range between A+X and BX, an alarm occurs; P is the pressure alarm deviation value. When the pressure of the hydrogen storage tank 18 is greater than C+P, the system alarms. When the pressure of the hydrogen storage tank 18 is greater than C+P1, there is a greater risk. If the opening of the vent valve 10 has reached the maximum, manual intervention is required.

[0045] In steps S1 and S3, the calculation method of the liquid hydrogen flow rate and liquid hydrogen pressure at the input end of the cold side flow path 14 is as follows:

[0046] S1.1, the enthalpy of hydrogen at the input end of the hot side flow path 12 is h1(p1, T1), where p1 is the hydrogen pressure at the input end of the hot side flow path 12, and T1 is the hydrogen temperature at the input end of the hot side flow path 12. The enthalpy of hydrogen at the output end of the hot side flow path 12 is set according to demand, h2(p2, T2), where p2 is the hydrogen pressure at the output end of the hot side flow path 12, and T2 is the hydrogen temperature at the output end of the hot side flow path 12. The required heat exchange amount of the hot side flow path 12 is calculated as Q1=q1(h1(p1, T1)-h2(p2, T2)), where q1 is the hydrogen flow rate in the hot side flow path 12;

[0047] S1.2, according to the heat exchange amount Q1 required by the hot side flow path 12 and the thermal efficiency k of the heat exchanger 16, the relationship between the liquid hydrogen enthalpy h3 at the input end of the cold side flow path 14 and the liquid hydrogen flow rate q2 of the cold side flow path 14 is obtained, and the calculation steps are as follows: According to the two stages of liquid hydrogen vaporization, the first stage is latent heat vaporization, that is, the heat Q3 absorbed by a unit mass of liquid hydrogen vaporized into hydrogen at the same temperature under a certain pressure; the second stage is the heat absorption and temperature rise of gaseous hydrogen. According to the thermodynamic formula Q4=cmΔT, c is the specific heat capacity, m is the mass, and ΔT is the difference between the outlet temperature of gaseous hydrogen on the cold side and the inlet temperature of liquid hydrogen on the cold side. Therefore, the cold released by liquid hydrogen vaporization is Q5=Q3+Q4=Q3+cmΔT. The cooling capacity Q5 released by the vaporization of liquid hydrogen is the heat exchange capacity of the heat exchanger. The pressure and temperature of the hydrogen at the output end of the cold side flow path 14 need to meet the standards of the hydrogenator, that is, the enthalpy value h4 of the hydrogen at the output end of the cold side flow path 14 is known. According to Q5= q2(h3(p3,T3)-h4(p4,T4)), when Q5, h4, and T3 are known, the relationship between the liquid hydrogen pressure p3 at the input end of the cold side flow path 14 and the liquid hydrogen flow rate q2 of the cold side flow path 14 can be obtained, thereby obtaining the liquid hydrogen flow rate and liquid hydrogen pressure corresponding to the required enthalpy value of the liquid hydrogen at the input end of the cold side flow path 14, that is, when the required enthalpy value of the liquid hydrogen at the input end of the cold side flow path 14 is determined, when the liquid hydrogen flow rate q2 is adjusted, the liquid hydrogen pressure at the input end of the cold side flow path 14 is also adjusted accordingly.

[0048] like Figure 2 As shown, the X coordinate in the image is the enthalpy coordinate, the Y coordinate is the pressure coordinate, the curve in the image is the saturation curve, and the multiple broken lines in the image are isotherms. Only one isotherm is shown in this image. The pressure of hydrogen at a certain temperature is determined by the enthalpy value and isotherm of hydrogen.

[0049] The above description of the disclosed embodiments enables one skilled in the art to implement or use the present invention. Various modifications to these embodiments will be apparent to one skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the present invention; therefore, the present invention will not be limited to the embodiments shown herein, but rather to the widest scope consistent with the principles and novel features disclosed herein.

[0050] Although this article uses more terms corresponding to the figure marks in the figures, it does not exclude the possibility of using other terms; these terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional limitations is contrary to the spirit of the present invention.

Claims

1. A liquid hydrogen precooling system, characterized in that: The heat exchanger (16) comprises a cold side flow path (14), a hot side flow path (12), a heat exchanger (16), a recuperator (17) and a collection component. The cold side flow path (14) and the hot side flow path (12) are respectively connected to the heat exchanger (16). The heat exchanger (16) exchanges heat between the cold side flow path (14) and the hot side flow path (12). The recuperator (17) and the collection component are respectively connected to the cold side flow path (14). The recuperator (17) is arranged between the collection component and the heat exchanger (16). A compressor (19) is provided at the output end of the collection component. The hot side flow path (12) is provided with a hot side inlet pressure transmitter (2), a hot side inlet temperature transmitter (3) and a hot side outlet temperature transmitter (4); the hot side inlet pressure transmitter (2) and the hot side inlet temperature transmitter (3) are arranged at the front end of the heat exchanger (16), and the hot side outlet temperature transmitter (4) is arranged at the rear end of the heat exchanger (16); A three-way valve (20) is provided at the output end of the hot side flow path (12), and the three-way valve (20) is connected to a collection component. When the hydrogen in the hot side flow path (12) does not meet the standards of the hydrogenator, the hydrogen in the hot side flow path (12) is directed to the collection component. The hot side outlet temperature transmitter (4) is electrically signal-connected to the three-way valve (20).

2. A liquid hydrogen precooling system according to claim 1, characterized in that: The output end of the cold side flow path (14) is provided with a venting pipeline (15) and a collecting pipeline (13); the collecting assembly is connected to the collecting pipeline (13); and the venting pipeline (15) is provided with a venting valve (10).

3. A liquid hydrogen precooling system according to claim 1, characterized in that: The collection assembly comprises a hydrogen storage tank (18) and a storage tank pressure transmitter (11), and the storage tank pressure transmitter (11) is electrically signal-connected to the vent valve (10).

4. A liquid hydrogen precooling system according to claim 1, characterized in that: The cold side flow path (14) is provided with a cold side inlet pressure transmitter (7), a cold side inlet temperature transmitter (8) and a cold side outlet temperature transmitter (9); the cold side inlet pressure transmitter (7) and the cold side inlet temperature transmitter (8) are arranged at the front end of the heat exchanger (16), and the cold side outlet temperature transmitter (9) is arranged at the rear end of the heat exchanger (16).

5. A liquid hydrogen precooling system according to claim 1, characterized in that: The input end of the cold side flow path (14) is provided with a cold side inlet regulating valve (6), and the hot side outlet temperature transmitter (4) is electrically connected to the cold side inlet regulating valve (6).

6. A liquid hydrogen precooling system according to claim 5, characterized in that: A hot side inlet regulating valve (1) is provided at the input end of the hot side flow path (12), and the cold side inlet regulating valve (6) is electrically signal-connected to the hot side inlet regulating valve (1).

7. A control method for a liquid hydrogen precooling system according to any one of claims 1 to 6, characterized in that: The following steps are included: S1, when the temperature of the hot side flow path (12) is greater than a set value A, the hydrogen in the hot side flow path (12) that does not meet the hydrogenation machine standard is directed to the collection component, and at the same time, the liquid hydrogen flow rate and liquid hydrogen pressure of the cold side flow path (14) are increased until the temperature of the hot side flow path (12) drops to the set value A, and the hot side flow path (12) is disconnected from the collection component, so that the hydrogen is output through the output end of the hot side flow path (12); S2, when the temperature of the hot side flow path (12) is greater than the set value A+X, where X is the temperature alarm deviation value, the system alarms and jumps back to step S1 for processing. If the liquid hydrogen flow rate of the cold side flow path (14) has reached the maximum, the flow rate of the hot side flow path (12) is reduced until the temperature of the hot side flow path (12) drops to the set value A; S3, when the temperature of the hot side flow path (12) is lower than the set value B, the liquid hydrogen flow rate and liquid hydrogen pressure of the cold side flow path (14) are reduced until the temperature of the hot side flow path (12) reaches the set value B; S4, when the temperature of the hot side flow path (12) is less than the set value BX, X is the temperature alarm deviation value, X ≥ 0, the system alarms and jumps back to step S3 for processing. If the liquid hydrogen flow rate of the cold side flow path (14) has reached the minimum, the flow rate of the hot side flow path (12) is increased until the temperature of the hot side flow path (12) rises to the set value B; S5, when the pressure of the collecting assembly is ≤C, all the hydrogen in the cold side flow path (14) is directed into the collecting assembly; when the pressure of the collecting assembly is >C, the hydrogen in the cold side flow path (14) is vented until the pressure of the collecting assembly is ≤C; S6, when the pressure of the collection component is greater than C+P, P is the pressure alarm deviation value, P≥0, the system alarms and jumps back to step S5 for processing; if the pressure of the collection component is greater than C+P1, P1 is the pressure alarm critical deviation value, P1>P≥0, the system alarms and prompts to manually open the collection component to vent.

8. The control method of a liquid hydrogen precooling system according to claim 7, characterized in that: In steps S1 and S3, the calculation method of the liquid hydrogen flow rate and liquid hydrogen pressure at the input end of the cold side flow path (14) is as follows: S1.1, the enthalpy value of hydrogen at the input end of the hot side flow path (12) is h1(p1, T1), the enthalpy value of hydrogen at the output end of the hot side flow path (12) is set according to demand, and the required heat exchange of the hot side flow path (12) is calculated, wherein p1 is the hydrogen pressure at the input end of the hot side flow path (12), T1 is the hydrogen temperature at the input end of the hot side flow path (12), p2 is the hydrogen pressure at the output end of the hot side flow path (12), and T2 is the hydrogen temperature at the output end of the hot side flow path (12); S1.2, according to the heat exchange amount required by the hot side flow path (12), the thermal efficiency of the heat exchanger (16), the enthalpy of the hydrogen at the output end of the cold side flow path (14), and the temperature of the liquid hydrogen at the input end of the cold side flow path (14), the enthalpy of the liquid hydrogen at the input end of the cold side flow path (14) is obtained, and the liquid hydrogen flow rate and liquid hydrogen pressure at the input end corresponding to the required enthalpy of the liquid hydrogen at the input end of the cold side flow path (14) are obtained.

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