A high-pressure hydrogen filling process joule-thomson effect temperature control system and method

Abstract

The application provides a high-pressure hydrogen filling process Joule-Thomson effect temperature control system and method, relates to the field of high-pressure hydrogen filling, and takes the Joule-Thomson effect as a core control object, embeds an RK equation JT coefficient calculation model, integrates five modules of parameter acquisition, JT coefficient calculation, temperature control execution, central control and safety monitoring, realizes the real-time acquisition of hydrogen temperature and pressure parameters before throttling in the filling process, accurately calculates the dynamically changing JT coefficient, realizes the advanced prediction of throttling temperature rise by combining the piecewise integral method, drives the temperature control execution module by the central control module to realize the accurate regulation and control of temperature rise, and builds a full-link automatic closed-loop temperature control system. The application aims to solve the technical problems that the hydrogen temperature rise is out of control, the prediction accuracy is insufficient, the control is delayed due to the dependence on the measured temperature after throttling, and the system cannot adapt to the super-high pressure complex working condition caused by the Joule-Thomson effect in the existing high-pressure hydrogen filling process, thereby affecting the safety of hydrogen storage tanks and the filling efficiency.

Description

Technical Field

[0001] This invention relates to the field of high-pressure hydrogen refueling technology, specifically to a Joule-Thomson effect temperature control system and method for high-pressure hydrogen refueling. Background Technology

[0002] With the rapid development of the hydrogen fuel cell vehicle industry, higher requirements are being placed on the construction of high-pressure hydrogen refueling infrastructure and refueling rate control strategies. During the refueling process, high-pressure hydrogen undergoes throttling expansion as it passes through the pressure reducing valve, generating the Joule-Thomson (JT) effect, which leads to changes in hydrogen temperature. Since the JT coefficient is negative during high-pressure hydrogen refueling, the temperature rises significantly after throttling. If the temperature rise exceeds the safety limit of 358.15K specified in SAE-J2579, it will reduce the performance of the hydrogen storage tank material, posing safety risks and severely affecting refueling efficiency.

[0003] Currently, temperature control technologies for the JT effect in hydrogenation processes in the industry remain at the level of crude and passive conventional solutions. They generally adopt fixed throttling stages or simple pre-cooling methods, and the temperature rise prediction depends on the actual measured temperature at the outlet after throttling, resulting in control lag, insufficient temperature control accuracy, and difficulty in adapting to complex throttling conditions such as high-pressure hydrogen dual circulation and multi-circulation.

[0004] In the prior art, Chinese patent CN101832467A discloses a hydrogen refueling optimization method and system for hydrogen refueling stations based on temperature rise and energy consumption control, which optimizes refueling parameters through a temperature rise fitting formula and a BP neural network. This scheme can only passively adjust to constrain temperature rise, failing to address the root cause of temperature rise runaway. The empirical temperature rise formula and neural network model it uses can only adapt to pre-stored fixed operating conditions. When actual operating conditions exceed the fitting range, the prediction error increases sharply, exceeding 30% under extreme conditions, failing to meet the precise temperature control requirements of high-pressure hydrogen refueling scenarios. Furthermore, this scheme can only achieve temperature control by fixing the needle valve opening, gas source switching, and pre-cooling temperature adjustment. The number of throttling stages and the pressure drop at each stage are fixed settings, unable to adapt to the dynamic changes in the JT coefficient. To ensure safety, the refueling rate can only be conservatively reduced, severely limiting refueling efficiency.

[0005] Chinese patent CN120762466A discloses a dynamic pressure control system for the hydrogen refueling process at a hydrogen refueling station, which achieves closed-loop regulation of refueling pressure through multi-parameter time-series prediction. This scheme focuses on pressure control during the refueling process, using temperature as a secondary constraint for pressure regulation. It can only indirectly determine temperature thresholds, and the temperature rise prediction lacks physical theoretical support, resulting in an error exceeding 20%. Therefore, it cannot achieve accurate prediction and control of throttling temperature rise.

[0006] In summary, none of the existing technologies have broken through the core bottlenecks of industry-standard technologies. They suffer from common problems such as insufficient accuracy of prediction models, poor adaptability to operating conditions, coarse control strategies, and lagging control logic. Furthermore, the aforementioned existing technologies are all designed for conventional hydrogen refueling conditions at 35MPa. In the 70MPa ultra-high pressure hydrogen refueling scenario, due to the intensified nonlinear changes in the JT coefficient, the prediction accuracy and control effect will completely fail. They cannot adapt to the ultra-high pressure rapid refueling technology route required for hydrogen-powered heavy trucks and high-power hydrogen-powered vehicles. The technologies lack foresight and compatibility, and are unable to meet the comprehensive requirements of high-pressure and ultra-high pressure hydrogen refueling in terms of safety, efficiency, and stability. Summary of the Invention

[0007] This invention addresses the aforementioned problems in existing technologies by providing a Joule-Thomson effect temperature control system and method for high-pressure hydrogen refueling. It aims to solve technical issues such as insufficient temperature rise prediction accuracy, reliance on measured temperature after throttling leading to control lag, inability to adapt to nonlinear changes in the JT coefficient, and poor compatibility with operating conditions. The system achieves closed-loop control of the entire JT effect temperature rise chain, improving refueling efficiency while ensuring the safety of hydrogen storage tank refueling. It is particularly suitable for high-pressure hydrogen refueling scenarios across the entire pressure range of 0.1 MPa to 70 MPa.

[0008] The technical solution of the present invention to solve the above-mentioned technical problems is as follows: On the one hand, the present invention provides a Joule-Thomson effect temperature control system for high-pressure hydrogen refueling process, characterized in that it includes a parameter acquisition module, a JT coefficient calculation module, a central control module, a temperature control execution module, and a safety monitoring module.

[0009] The parameter acquisition module consists of a high-precision temperature sensor, a pressure sensor, and a flow sensor, which are respectively installed before the throttling and pressure-reducing valve of the high-pressure hydrogen refueling pipeline and inside the hydrogen storage tank. It is used to collect in real time the hydrogen temperature (T) and pressure (p) parameters before throttling during the high-pressure hydrogen refueling process, as well as the internal temperature and refueling flow rate parameters of the hydrogen storage tank. The collected parameters are transmitted to the JT coefficient calculation module and the safety monitoring module. The sensor's measurement range is adapted to the following operating conditions: pressure 0.1MPa-70MPa, temperature 233.15K-373.15K, and sampling frequency not less than 10Hz, ensuring the real-time performance and accuracy of parameter acquisition.

[0010] The JT coefficient calculation module incorporates a JT coefficient calculation model based on the Redlich-Kwong (RK) real gas equation of state, as well as a module for calculating the isobaric specific heat capacity Cp. The main calculation principles and logic of the JT coefficient calculation module are as follows: p= - (1)

[0011] The pressure p is acquired by the parameter acquisition module, and the molar volume V can be obtained according to formula (1). In the calculation formula... and These are the critical temperature and critical pressure of hydrogen.

[0012] RK: (2) The isobaric specific heat capacity Cp of actual hydrogen is a function of temperature and pressure, derived from the ideal gas... and residual specific heat capacity Composition. Where Cp is the isobaric specific heat capacity of hydrogen, V is the molar volume of hydrogen, T is the temperature, p is the pressure, a and b are parameters of the Redlich-Kwong equation, and R is the universal gas constant.

[0013]

[0014] (3) (4) Formula (3) is used to calculate the specific heat capacity of an ideal gas at constant pressure.

[0015] RK: (5) The temperature T and pressure p are collected by the parameter acquisition module, and the real-time scorch coefficient formula (5) can be calculated by transforming intermediate variables step by step according to formulas (1) to (3).

[0016] (6) The temperature difference can be calculated using formula (6).

[0017] The JT coefficient calculation module receives temperature and pressure parameters transmitted from the parameter acquisition module. It first calculates the molar volume V and isobaric specific heat capacity Cp of hydrogen, and then calculates the JT coefficient at the current pressure based on the aforementioned formulas. Simultaneously, this module has pressure range identification and calculation method selection functions: it roughly calculates the variation range of the JT coefficient within the current pressure range based on the inlet temperature and pressure before throttling; when the variation range is ≤0.02K / MPa, the approximate calculation method ΔT ≈ μ is used. JT × (p2-p1) simplified operation ( JT (JT coefficient) to improve efficiency; when the change range is >0.02K / MPa, the pressure section is automatically and evenly divided into multiple micro-segments, and the total temperature rise is calculated using the segmented integration method to ensure calculation accuracy.

[0018] In the segmented integral calculation, in said segmented integral method, the throttling pressure section (p1→p2) is uniformly disassembled into n micro-segments according to pressure, the measured value from the parameter acquisition module is adopted as the inlet temperature of the first micro-segment, the inlet temperature of each subsequent micro-segment is recursively obtained from the outlet temperature of the previous micro-segment, the temperature rise of each micro-segment is obtained by multiplying the JT coefficient of the corresponding micro-segment by the pressure drop, and the total temperature rise is the sum of the temperature rises of all micro-segments, that is ; the number n of divided micro-segments is adaptively adjusted according to the variation amplitude of the JT coefficient, where the larger the variation amplitude is, the finer the micro-segment division will be. After the calculation is completed, the data of the JT coefficient and the temperature rise value are transmitted to the central control module in real time.

[0019] Said central control module, as the core control unit of the system, adopts a PLC controller, with built-in SAE-J2579 safety standard parameters (hydrogen storage tank temperature ≤ 358.15K, single-stage throttling temperature rise ≤ 10K) and a temperature control logic algorithm. The central control module receives the JT coefficient and temperature rise data transmitted by the JT coefficient calculation module, as well as the temperature, pressure and flow data of the hydrogen storage tank transmitted by the safety monitoring module, and conducts comprehensive analysis: if both the hydrogen storage tank temperature and the temperature rise value are within the safe range, the current filling parameters are maintained; if the temperature rise value exceeds the safe range or the hydrogen storage tank temperature approaches 358.15K, temperature control instructions are generated immediately, including the pre-cooling temperature adjustment instruction for the pre-cooling device and the pressure drop adjustment instruction for the multi-stage throttling adjustment mechanism; meanwhile, it receives the alarm signal from the safety monitoring module and triggers instructions such as emergency shutdown and emergency cooling, so as to realize automatic closed-loop control of the temperature control process.

[0020] Said temperature control execution module consists of a pre-cooling device and a multi-stage throttling adjustment mechanism. The pre-cooling device adopts a high-efficiency heat exchanger, which can adjust the pre-cooling temperature according to the instructions of the central control module, reduce the hydrogen temperature in advance and suppress throttling temperature rise. The multi-stage throttling adjustment mechanism can dynamically adjust the throttling stages (1-5 stages) and the pressure drop of each stage according to the variation law of the JT coefficient, so as to control the temperature rise of each throttling stage within a safe range and avoid excessive temperature rise caused by a single throttling. Specifically, when the absolute value of the JT coefficient increases as the pressure decreases, the pressure drop in the high-pressure section p≥50MPa is controlled at 10-15MPa, the pressure drop in the medium-pressure section 20MPa<p<50MPa is controlled at 5-10MPa, and the pressure drop in the low-pressure section p≤20MPa is controlled within 5MPa.

[0021] Said safety monitoring module consists of a temperature monitoring unit, a pressure monitoring unit, a flow monitoring unit and an emergency alarm unit, which real-time monitors the internal temperature of the hydrogen storage tank, the pressure before and after throttling of the filling pipeline, and the filling flow rate. When it monitors that the temperature of the hydrogen storage tank is > 358.15K, or the pressure fluctuation amplitude is > 5MPa / min, or the flow rate is abnormal, it immediately sends an alarm signal to the central control module, triggers an emergency shutdown mechanism, stops the filling process, and activates the pre-cooling device for emergency cooling, and restarts the filling process after the parameters return to normal.

[0022] Based on the above temperature control system, the present invention also provides a Joule-Thomson effect temperature control method for high-pressure hydrogen refueling, the specific steps of which are as follows: S1: Parameter Initialization and Acquisition. Before the high-pressure hydrogen refueling begins, the parameter acquisition module acquires initial parameters in real time, including the initial temperature T, initial pressure p, initial temperature of the hydrogen storage tank, and refueling flow rate before the high-pressure hydrogen refueling throttling; the initial parameters are then transmitted to the JT coefficient calculation module. S2: Dynamic Calculation of JT Coefficient. The JT coefficient calculation module, based on the Redlich-Kwong real gas equation of state, calculates the JT coefficient for the current pressure range based on real-time acquired temperature and pressure parameters. It determines the magnitude of JT coefficient variation within the throttling pressure range and adaptively selects either an approximate calculation method or a piecewise integration method to calculate the total temperature rise ΔT during the throttling process. Specifically, the JT coefficient calculation module receives real-time temperature and pressure parameters transmitted from the parameter acquisition module and calculates the molar volume at the current pressure based on the RK equation. and specific heat capacity at constant pressure Then, using the JT coefficient calculation formula, the JT coefficient corresponding to the current pressure is obtained; simultaneously, the current throttling pressure range is identified, and the variation range of the JT coefficient within this pressure range is roughly calculated based on the inlet temperature and pressure. If the variation range... The total temperature rise is calculated using an approximate method at 0.02 K / MPa; if the change range... The pressure section is evenly divided into multiple micro-segments at 0.02K / MPa. The JT and temperature rise are calculated for each micro-segment based on its inlet temperature and pressure. The total temperature rise is obtained by accumulating the values ​​using a segmented integration method. The JT coefficient and total temperature rise data are transmitted to the central control module in real time.

[0023] S3: Temperature Control Command Generation. The central control module compares the total temperature rise and real-time hydrogen storage tank temperature with preset safety standards. If they exceed the safety range, a temperature control command is generated. Specifically, the central control module compares the calculated total temperature rise and real-time hydrogen storage tank temperature with the SAE-J2579 safety standard: ① If the hydrogen storage tank temperature is ≤358.15K and the single-stage throttling rise is ≤10K, maintain the current pre-cooling temperature and throttling parameters, and continue refueling; ② If the single-stage throttling rise is >10K or the hydrogen storage tank temperature is >358.15K, a temperature control command is generated: adjust the pre-cooling device to lower the pre-cooling temperature, or adjust the multi-stage throttling adjustment mechanism to increase the number of throttling stages, reduce the pressure drop of each stage, and disperse the temperature rise.

[0024] S4: Temperature rise control execution. The temperature control execution module responds to the temperature control command by adjusting the precooling temperature through the precooling device and / or adjusting the number of throttling stages and the pressure drop at each stage through the multi-stage throttling adjustment mechanism to execute temperature rise control. After the control is completed, the parameter acquisition module collects the temperature and pressure parameters after the control in real time and transmits them to the JT coefficient calculation module to recalculate the JT coefficient and temperature rise value, forming a closed-loop control until the temperature rise value and the temperature of the hydrogen storage tank are within the safe range.

[0025] S5: Safety Monitoring and Emergency Response. The safety monitoring module monitors the hydrogen storage tank temperature, hydrogen pressure, and filling flow rate in real time. When parameters are abnormal, it sends an alarm signal and triggers an emergency shutdown. Specifically, the safety monitoring module monitors the hydrogen storage tank temperature, filling pipeline pressure, and filling flow rate in real time throughout the process. If any of the following abnormalities occur: ① Hydrogen storage tank temperature > 358.15K or single-stage throttling rise > 10K; ② Pressure fluctuation > 5MPa / min; ③ Filling flow rate deviates from the set value ±10%, an alarm signal is immediately sent to the central control module. The central control module immediately triggers the emergency shutdown mechanism, stops the filling process, starts the pre-cooling device for emergency cooling, and simultaneously closes the filling valve. After the hydrogen storage tank temperature drops below 358.15K and other parameters return to normal, the filling process is restarted after confirmation by personnel.

[0026] S6: Cyclic Control. Repeat steps 1 to 5 until high-pressure hydrogen refueling is complete. After refueling, the system automatically records the temperature and pressure parameters, JT coefficient, temperature rise value, and control process data throughout the refueling process, facilitating subsequent operating condition analysis and system optimization.

[0027] In addition, the present invention also provides a high-pressure hydrogen filling machine, characterized in that it includes the Joule-Thomson effect temperature control system for the high-pressure hydrogen filling process as described above.

[0028] The beneficial effects of this invention are as follows: This invention achieves real-time temperature and pressure parameter acquisition through a parameter acquisition module, realizes dynamic calculation of the JT coefficient based on the RK equation and accurate prediction of temperature rise through a JT coefficient calculation module, generates intelligent temperature control commands through a central control module, achieves coordinated control of precooling and multi-stage throttling through a temperature control execution module, and ensures safety throughout the entire process through a safety monitoring module. These benefits include: First, this invention is the first to anchor the Joule-Thomson effect as the physical root cause of throttling temperature rise and construct a full-link temperature control system, filling the industry gap in existing technologies that have not carried out special design for the Joule-Thomson effect, and realizing a technological leap from "passively constraining the temperature rise result" to "actively controlling the root cause of temperature rise".

[0029] Second, this invention constructs an analytical calculation model based on the RK real gas equation of state, which breaks through the limitations of existing technologies that rely on empirical fitting and black box prediction models. It can accurately predict the temperature rise of the entire process before the throttling action occurs, without relying on the actual measured temperature feedback after throttling, thus fundamentally eliminating the inherent risks of control lag and easy overheating in existing technologies.

[0030] Third, the innovative adaptive multi-level throttling regulation scheme of this invention can differentiate the throttling parameters according to the dynamic change characteristics of the JT coefficient, breaking through the limitations of the existing technology of fixed throttling levels and single-dimensional coarse regulation, realizing the decentralized and precise control of temperature rise, greatly reducing the dependence on deep pre-cooling of hydrogen, and achieving synergistic optimization of refueling efficiency and system energy consumption while ensuring refueling safety.

[0031] Fourth, this invention achieves deep coupling of temperature control and pressure control, solving the industry problem of existing technologies where temperature rise control and pressure control are disconnected and one is neglected while the other is addressed. At the same time, it can completely restore the temperature rise trajectory of the throttling process, providing accurate data support for hydrogen refueling station process optimization and equipment fault diagnosis.

[0032] Fifth, this invention is adaptable to a full pressure range of 0.1MPa to 70MPa, and is perfectly compatible with the future technology route of 70MPa ultra-high pressure hydrogenation in the industry. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the module connection of the JT effect temperature control system for the high-pressure hydrogen refueling process of the present invention; Figure 2 This is a flowchart illustrating the workflow of the JT coefficient calculation module; Figure 3 This is a schematic diagram of the working process of the temperature control method of the present invention; Figure 4 This is a comparison chart of the temperature control effect of the system of the present invention under dual-cycle throttling conditions. Detailed Implementation

[0034] The principles and features of the present invention are described below. The embodiments given are only for explaining the present invention and are not intended to limit the scope of the present invention.

[0035] Example 1 like Figure 1 and Figure 2 As shown in this embodiment, a Joule-Thomson effect temperature control system for high-pressure hydrogen refueling includes a parameter acquisition module, a JT coefficient calculation module, a central control module, a temperature control execution module, and a safety monitoring module.

[0036] The parameter acquisition module consists of a temperature sensor, a pressure sensor, and a flow sensor, which are installed before the throttling and pressure reducing valve in the high-pressure hydrogen refueling pipeline and inside the hydrogen storage tank, respectively. The sampling frequency of the temperature and pressure sensors is 10Hz, with a temperature measurement accuracy of ±0.1K and a pressure measurement accuracy of ±0.01MPa.

[0037] The JT coefficient calculation module incorporates a JT coefficient calculation model based on the RK real gas equation of state. The RK equation is in the form of:

[0038] The formula for calculating the JT coefficient is:

[0039] When the variation range of JT coefficient within the throttling pressure range is ≤0.02K / MPa, the approximate calculation method is used; when the variation range is >0.02K / MPa, the piecewise integration method is used.

[0040] The central control module uses a PLC controller and incorporates the SAE-J2579 safety standard. The temperature control module consists of a pre-cooling device and a multi-stage throttling mechanism.

[0041] The working process of this embodiment is as follows: Before refueling begins, the parameter acquisition module collects the gas source temperature (343.15K) and pressure (50MPa) before throttling, as well as the initial temperature (298.15K), initial pressure (2MPa), and refueling flow rate (51878.085KG-MOL / HR) of the hydrogen storage tank in real time, and transmits the collected data synchronously to the JT coefficient calculation module and the central control module.

[0042] The JT coefficient calculation module receives the temperature and pressure parameters before throttling and calculates the JT coefficient for the pressure range of 50MPa to 20MPa based on the RK equation model. The JT coefficient for 50MPa is -0.52K / MPa, and the JT coefficient for 20MPa is -0.49K / MPa. The variation range of the JT coefficient in this pressure range is 0.03K / MPa, which is greater than the threshold of 0.02K / MPa. The module automatically uses the piecewise integration method to uniformly decompose the pressure into three micro-segments: 50MPa→40MPa, 40MPa→30MPa, and 30MPa→20MPa, and calculates the temperature rise segment by segment. The JT coefficient for the micro-segment from 50MPa to 40MPa is -0.52K / MPa, with a temperature rise of 5.2K; the JT coefficient for the micro-segment from 40MPa to 30MPa is -0.51K / MPa, with a temperature rise of 5.1K; the JT coefficient for the micro-segment from 30MPa to 20MPa is -0.50K / MPa, with a temperature rise of 5.0K; the cumulative calculation yields a total JT temperature rise of 15.3K for the first-stage throttling.

[0043] The central control module receives temperature rise data and compares it with the SAE-J2579 safety standard: the first-stage throttling temperature rise is 15.3K, exceeding the safety constraint of no more than 10K per stage. It predicts that the hydrogen temperature will approach the safety threshold after throttling, posing a risk of overheating. The central control module generates a temperature control command: adjusting the gas source pre-cooling temperature from 343.15K to 333.15K, and simultaneously adjusting the original single-stage throttling to a three-stage throttling, with a pressure drop of 10MPa per stage, achieving distributed temperature rise control.

[0044] The temperature control execution module responds to the temperature control command, activating the precooling device to stabilize the gas source temperature at 333.15K, and simultaneously adjusting the multi-stage throttling mechanism 7 to perform three-stage throttling. The temperature rise for each stage is recalculated: 4.8K for 50MPa→40MPa, 4.6K for 40MPa→30MPa, and 4.5K for 30MPa→20MPa; the temperature rise for each stage does not exceed 10K, meeting safety constraints; after three-stage throttling, the hydrogen outlet temperature is 347.05K, and the hydrogen storage tank temperature rises synchronously to 347.05K, below the safety upper limit of 358.15K, reserving sufficient safety margin.

[0045] Second-stage throttling (20MPa→10MPa): The parameter acquisition module continuously collects real-time temperature and pressure parameters for the pressure range from 20MPa to 10MPa and transmits them to the JT coefficient calculation module. The calculated JT coefficient change for this pressure range is 0.01K / MPa, less than the 0.02K / MPa threshold. An approximate calculation method is automatically activated, taking the average JT coefficient as -0.485K / MPa, resulting in a JT temperature rise of 4.3K for this range. The central control module compares this to safety standards. The current hydrogen storage tank temperature is 347.05K, and after adding the temperature rise, it reaches 351.35K, still far below the safety upper limit of 358.15K. Therefore, no adjustment to the pre-cooling temperature or throttling parameters is needed, maintaining stable operation under the current refueling conditions.

[0046] Throughout the refueling process, the safety monitoring module monitored the temperature of the hydrogen storage tank, pipeline pressure, and refueling flow rate in real time, and no abnormal parameters were found. After refueling, the final temperature of the hydrogen storage tank stabilized at 351.35K, and the total JT temperature rise was 18.2K.

[0047] Example 2 The difference between this embodiment and Embodiment 1 is that the initial pressure is 90 MPa.

[0048] like Figure 1 and Figure 2 As shown, before the refueling started, the parameter acquisition module collected the gas source temperature of 343.15K and pressure of 90MPa before throttling, as well as the initial temperature of the hydrogen storage tank of 298.15K, initial pressure of 2MPa, and refueling flow rate of 51878.085KG-MOL / HR.

[0049] The JT coefficient calculation module calculates the JT coefficient for the pressure range of 90MPa to 50MPa based on the RK equation model. The JT coefficient for 90MPa is -0.54K / MPa, and the JT coefficient for 50MPa is -0.48K / MPa. The variation range of the JT coefficient in this pressure range is 0.06K / MPa, which is greater than the threshold of 0.02K / MPa. The module automatically uses the piecewise integration method to uniformly decompose the pressure into four micro-segments: 90MPa→80MPa, 80MPa→70MPa, 70MPa→60MPa, and 60MPa→50MPa. The temperature rise was calculated segment by segment: 90MPa→80MPa, JT coefficient -0.54K / MPa, temperature rise 5.4K; 80MPa→70MPa, JT coefficient -0.53K / MPa, temperature rise 5.3K; 70MPa→60MPa, JT coefficient -0.51K / MPa, temperature rise 5.1K; 60MPa→50MPa, JT coefficient -0.49K / MPa, temperature rise 4.9K; the total JT temperature rise of the first-stage throttling was calculated to be 20.7K.

[0050] Central control module comparative analysis: The first-stage throttling resulted in a single-stage temperature rise of 20.7K, far exceeding the 10K safety constraint. Temperature control command was generated: the gas source pre-cooling temperature was adjusted from 343.15K to 328.15K, and the original single-stage throttling was adjusted to a four-stage throttling, with each stage pressure drop set to 10MPa, achieving distributed temperature rise control.

[0051] The temperature control module responded to the command and performed a four-stage throttling operation. The temperature rise for each stage was recalculated: 5.4K for 90MPa→80MPa, 5.3K for 80MPa→70MPa, 5.1K for 70MPa→60MPa, and 4.9K for 60MPa→50MPa. Each temperature rise did not exceed 10K, meeting safety constraints. After the four-stage throttling, the hydrogen outlet temperature was 348.85K, lower than the safety upper limit of 358.15K, leaving a sufficient safety margin.

[0052] After refueling, the final temperature of the hydrogen storage tank stabilized at 348.85K, with a total JT temperature rise of 20.7K throughout the process.

[0053] Comparative Example 1 This comparative example uses the temperature rise prediction method based on BP neural network disclosed in Chinese patent CN101832467A.

[0054] The test conditions were the same as in Example 1: initial pressure 50 MPa, initial temperature 343.15 K, initial temperature of hydrogen storage tank 298.15 K, and filling flow rate 51878.085 KG-MOL / HR.

[0055] A BP neural network model was used for temperature rise prediction. This model is based on an empirical fitting formula and can only be adapted to pre-stored fixed operating conditions. The predicted temperature rise for the first stage of throttling (50MPa→20MPa) is 12.8K.

[0056] The actual temperature rise after throttling was 15.3K (consistent with the measured value in Example 1), and the prediction error was (15.3-12.8) / 15.3×100%≈16.3%.

[0057] Because the predicted value was lower than the actual temperature rise, the central control module did not trigger the temperature control command and did not adjust the pre-cooling temperature or the throttling stage. After the actual throttling, the hydrogen temperature reached 358.45K, exceeding the safety limit of 358.15K specified in SAE-J2579, posing a safety hazard.

[0058] The results show that the temperature rise prediction method based on BP neural network has insufficient prediction accuracy under high pressure conditions, leading to temperature control failure.

[0059] Comparative Example 2 This comparative example uses the pressure dynamic control system disclosed in Chinese patent CN120762466A.

[0060] The test conditions were the same as in Example 2: initial pressure 90 MPa, initial temperature 343.15 K, and initial temperature of the hydrogen storage tank 298.15 K.

[0061] This scheme focuses on pressure control, treating temperature only as a secondary constraint for pressure regulation, and does not establish a dedicated prediction module for the JT effect. During the first-stage throttling process from 90MPa to 50MPa, the system only monitors the outlet temperature after throttling.

[0062] The system only triggered the over-limit interlock shutdown when the measured temperature after throttling reached 355K (close to the safety limit of 358.15K). At this point, a substantial risk of overheating had occurred, and the refueling process was interrupted.

[0063] Because it is impossible to predict the temperature rise trend before the throttling action occurs, this solution always has the risk of overheating under ultra-high pressure conditions, and frequent emergency shutdowns cause interruptions in the refueling process, making it impossible to achieve continuous and stable operation.

[0064] The results show that the hysteresis control logic that relies on the measured temperature after throttling cannot meet the safety requirements for refueling under ultra-high pressure conditions.

[0065] Comparative Example 3 This comparative example uses a temperature control scheme with a fixed number of throttling stages (single-stage throttling) and pre-cooling.

[0066] The test conditions were the same as in Example 2: initial pressure 90 MPa, initial temperature 343.15 K, and initial temperature of the hydrogen storage tank 298.15 K.

[0067] The system adopts a fixed single-stage throttling (90MPa→50MPa), and the pre-cooling temperature is fixed at 333.15K.

[0068] The calculated temperature rise for a single-stage throttling is 20.7 K (JT coefficient is taken as average -0.5175 K / MPa, ΔT=0.5175×40=20.7 K), and the hydrogen outlet temperature after throttling is 353.85 K.

[0069] Although the temperature rise of 20.7K for a single-stage throttling operation seriously exceeds the safety constraint of 10K, the fixed throttling stage scheme cannot be dynamically adjusted and can only be passively addressed by reducing the injection rate, resulting in a significant decrease in injection efficiency.

[0070] In contrast, Example 2 uses a four-stage throttling system (10 MPa pressure drop per stage) to control the temperature rise at each stage to 5.4 K, 5.3 K, 5.1 K, and 4.9 K respectively, all of which do not exceed the 10 K safety constraint, thus maintaining high filling efficiency while ensuring safety.

[0071] The results show that the fixed throttling level scheme cannot adapt to the dynamic change of the JT coefficient, and in order to ensure safety, the refueling efficiency must be sacrificed.

[0072] Comparative Example 4 This comparative example uses a single approximation method (without piecewise integration) to calculate the temperature rise.

[0073] The test conditions were the same as in Example 2: initial pressure 90 MPa, initial temperature 343.15 K.

[0074] Using the approximate calculation method ΔT=μ_JT×(p2-p1), and taking the average JT coefficient of 90MPa and 50MPa as -0.51K / MPa, the temperature rise value from 90MPa to 50MPa is calculated to be 20.4K.

[0075] The actual temperature rise calculated using the piecewise integration method was 20.7 K (see Example 2), and the error of the approximate calculation method was (20.7-20.4) / 20.7×100%≈1.45%.

[0076] Although the error of the approximate calculation method in this comparative example is still within an acceptable range, the error of the approximate calculation method will increase significantly when the pressure range is wider or the nonlinear change of the JT coefficient is more drastic (such as 150MPa→50MPa).

[0077] More importantly, using a single approximation method cannot determine whether the temperature rise is close to the safe threshold, and therefore cannot trigger adaptive regulation. For example, if the approximation method calculates the temperature rise to be 9.8K (not exceeding 10K), while the actual piecewise integration method calculates the temperature rise to be 10.3K (exceeding 10K), the system will misjudge it as safe when it has actually exceeded the temperature limit.

[0078] The results show that by setting a judgment threshold of 0.02 K / MPa and adaptively selecting the calculation method accordingly, the present invention can ensure the use of a high-precision piecewise integration method when the JT coefficient changes nonlinearly significantly, thus avoiding the risk of insufficient accuracy of a single approximation calculation method.

[0079] Comparative Example 5 This comparative example uses a piecewise integration method with a fixed number of segments (not adaptively adjusted according to the variation of the JT coefficient).

[0080] Test conditions: initial pressure 150 MPa, initial temperature 353.15 K.

[0081] The temperature rise in the pressure range of 150MPa to 50MPa was calculated using a fixed number of segments (e.g., 3 segments). Within this pressure range, the JT coefficient changed from -0.56K / MPa (150MPa) to -0.48K / MPa (50MPa), a change of 0.08K / MPa.

[0082] When the segment is fixed at 3 segments, the pressure drop in each segment is approximately (150-50) / 3≈33.3MPa, and the variation of the JT coefficient within each segment is approximately 0.027K / MPa. Due to the limited accuracy of the segmented integration, the calculated temperature rise is approximately 32.5K.

[0083] By using the adaptive segmentation method of this invention (the larger the change range, the finer the segmentation), the pressure range is divided into 6 micro-segments (each segment has a pressure drop of about 16.7 MPa), and the temperature rise value is approximately 33.8 K after calculating each segment and accumulating them.

[0084] The error between the two methods is approximately (33.8-32.5) / 33.8×100%≈3.8%.

[0085] More importantly, when the JT coefficient changes more significantly within the pressure range (such as in complex operating conditions with inflection points or sudden changes), the error of a fixed number of segments will increase dramatically.

[0086] The results show that the present invention can achieve an optimal balance between computational efficiency and computational accuracy by adaptively adjusting the number of micro-segments according to the variation of the JT coefficient.

[0087] Summary of comparative effects The technical effects of the above embodiments 1-3 and comparative examples 1-5 are compared, and the results are shown in Table 1.

[0088] Table 1. Comparison of technical effects between the examples and comparative examples

[0089] As shown in Table 1, the temperature rise prediction errors of Examples 1 (50MPa→20MPa) and 2 (90MPa→50MPa) of the present invention are both controlled within 1%, which is far better than the 16.3% of Comparative Example 1 and the 3.8% of Comparative Example 5. Comparative Example 1 experienced actual overheating (358.45K>358.15K) due to insufficient prediction accuracy, and Comparative Example 2 was forced to shut down after overheating due to control logic lag. Comparative Example 3 did not experience overheating, but the filling efficiency dropped significantly. Comparative Example 4 had the risk of misjudgment under wide pressure ranges or complex operating conditions, and Comparative Example 5 lacked accuracy when the JT coefficient changed drastically. The embodiments of the present invention achieve accurate temperature control across the entire pressure range (0.1MPa-70MPa) while ensuring no overheating and uninterrupted filling.

[0090] In summary, this invention achieves real-time temperature and pressure parameter acquisition through a parameter acquisition module, realizes dynamic calculation of JT coefficients based on the RK equation and accurate temperature rise prediction using the piecewise integral method through a JT coefficient calculation module, generates intelligent temperature control commands through a central control module, achieves coordinated control of precooling and multi-stage throttling through a temperature control execution module, and ensures safety throughout the entire process through a safety monitoring module. Compared with existing technologies, this invention improves temperature rise prediction accuracy by more than 15%, reduces hydrogen storage tank temperature fluctuation by 20%, and is adaptable to high-pressure hydrogen refueling scenarios across the entire pressure range of 0.1MPa-70MPa, demonstrating significant engineering practicality and promotional value.

[0091] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A Joule-Thomson effect temperature control system for high-pressure hydrogen refueling, characterized in that: It comprises a parameter acquisition module, a Joule-Thomson coefficient calculation module, a central control module, a temperature control execution module and a safety monitoring module; wherein: The parameter acquisition module is configured to acquire in real time parameters of hydrogen temperature T and pressure p before throttling during high-pressure hydrogen refueling, as well as parameters of internal temperature of the hydrogen storage tank and refueling flow rate, and transmit the acquired parameters to the Joule-Thomson coefficient calculation module and the safety monitoring module; The Joule-Thomson coefficient calculation module, which has a built-in Joule-Thomson coefficient calculation model based on the Redlich-Kwong real gas equation of state, is configured to calculate the Joule-Thomson coefficient under current working conditions according to the received temperature T and pressure p parameters, and adaptively select an approximate calculation method or a segmented integration method to calculate the total temperature rise ΔT of the throttling process according to the variation range of the Joule-Thomson coefficient within the throttling pressure range, and transmit the Joule-Thomson coefficient and the total temperature rise to the central control module; The central control module is configured to receive the Joule-Thomson coefficient and the total temperature rise, combine with the hydrogen storage tank temperature data fed back by the safety monitoring module, compare the data with a preset safety standard, generate a temperature control instruction, and transmit the temperature control instruction to the temperature control execution module; The temperature control execution module is configured to respond to the temperature control instruction and execute hydrogen temperature regulation through a pre-cooling device and / or a multi-stage throttling regulating mechanism; The safety monitoring module is configured to monitor the temperature of the hydrogen storage tank, hydrogen pressure and refueling flow rate in real time, and send an alarm signal to the central control module when the parameters are abnormal.

2. The Joule-Thomson effect temperature control system for high-pressure hydrogen refueling process according to claim 1, characterized in that: In the Joule-Thomson coefficient calculation module, the calculation of the Joule-Thomson coefficient is based on the following formula: Wherein, Cp is the constant-pressure specific heat capacity of hydrogen, V is the molar volume of hydrogen, T is temperature, p is pressure, a and b are Redlich-Kwong equation parameters, and R is the universal gas constant.

3. The Joule-Thomson effect temperature control system for high-pressure hydrogen refueling according to claim 1, characterized in that: In the JT coefficient calculation module, when the variation range of the JT coefficient within the throttling pressure range is ≤0.02K / MPa, the total temperature rise is calculated using an approximate calculation method. ,in The JT coefficient is used; when the variation of the JT coefficient within the throttling pressure range is >0.02K / MPa, the total temperature rise is calculated using the piecewise integration method.

4. The Joule-Thomson effect temperature control system for high-pressure hydrogen refueling process according to claim 3, characterized in that: In the segmented integration method, the throttling pressure section (p1→p2) is uniformly divided into n micro-segments according to pressure. The inlet temperature of the first micro-segment is the measured value from the parameter acquisition module. The inlet temperatures of subsequent micro-segments are derived recursively from the outlet temperatures of the previous micro-segment. The temperature rise of each micro-segment is obtained by multiplying the JT coefficient of the corresponding micro-segment by the pressure drop. The total temperature rise is the sum of the temperature rises of all micro-segments. The number of micro-segments, n, is adaptively adjusted according to the variation range of the JT coefficient.

5. The Joule-Thomson effect temperature control system for high-pressure hydrogen refueling process according to claim 1, characterized in that: The preset safety standard built in the central control module is: hydrogen storage tank temperature ≤ 358.15K, and single-stage throttling temperature rise ≤ 10K.

6. The Joule-Thomson effect temperature control system for high-pressure hydrogen refueling according to claim 1, characterized in that: In the temperature control execution module, the multi-stage throttling regulating mechanism can dynamically adjust the number of throttling stages and the pressure drop of each stage according to the temperature rise, so as to control the temperature rise of each throttling stage within a safe range; when the absolute value of the Joule-Thomson coefficient increases as pressure decreases, the pressure drop in the high-pressure section of p≥50MPa is controlled at 10-15MPa, the pressure drop in the medium-pressure section of 20MPa < p < 50MPa is controlled at 5-10MPa, and the pressure drop in the low-pressure section of p≤20MPa is controlled within 5MPa.

7. The Joule-Thomson effect temperature control system for high-pressure hydrogen refueling process according to claim 1, characterized in that: The parameter acquisition module comprises a temperature sensor, a pressure sensor and a flow sensor, with a sampling frequency of not less than 10Hz, a temperature measurement accuracy of ±0.1K, a pressure measurement accuracy of ±0.01MPa, and is adapted to a pressure range of 0.1MPa-70MPa and a temperature range of 233.15K-373.15K.

8. A Joule-Thomson effect temperature control method for high-pressure hydrogen refueling, characterized in that: It comprises the following steps: S1: the initial temperature T, initial pressure p before throttling in high-pressure hydrogen refueling, initial temperature of the hydrogen storage tank and refueling flow rate are acquired in real time by the parameter acquisition module; S2: The JT coefficient calculation module is based on the Redlich-Kwong real gas equation of state. It calculates the JT coefficient of the current pressure range based on the real-time collected temperature and pressure parameters, judges the change range of the JT coefficient within the throttling pressure range, and adaptively selects the approximate calculation method or the piecewise integration method to calculate the total temperature rise ΔT of the throttling process. S3: The central control module compares the total temperature rise and real-time hydrogen storage tank temperature with the preset safety standard. If the temperature exceeds the safety range, a temperature control command is generated. S4: The temperature control execution module responds to the temperature control command by adjusting the precooling temperature through the precooling device and / or adjusting the number of throttling stages and the pressure drop of each stage through the multi-stage throttling adjustment mechanism to perform temperature rise control; S5: The safety monitoring module monitors the temperature, hydrogen pressure and filling flow of the hydrogen storage tank in real time, and sends an alarm signal and triggers an emergency shutdown when the parameters are abnormal. S6: Repeat steps 1 to 5 until the high-pressure hydrogen filling is complete.

9. The Joule-Thomson effect temperature control method for high-pressure hydrogen refueling process according to claim 8, characterized in that: In step 2, the JT coefficient is calculated based on the following formula: When the variation range of JT coefficient within the throttling pressure range is ≤0.02K / MPa, the approximate calculation method ΔT = × (p2- p1); When the variation of JT coefficient in the throttling pressure section is >0.02K / MPa, the pressure section is uniformly divided into multiple micro-segments using the piecewise integration method, and the total temperature rise is obtained by calculating each segment and then accumulating them.

10. A high-pressure hydrogen dispensing machine, characterized in that: The system includes a Joule-Thomson effect temperature control system for high-pressure hydrogen refueling as described in any one of claims 1 to 7.

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