Self-learning hydrogenation pressure loss estimation method of hydrogenation system

Abstract

The invention discloses a self-learning hydrogenation pressure loss estimation method for a hydrogenation system, and the method comprises the steps: carrying out the approximation of a filling link from a snap valve to a gas cylinder inlet, supposing that a valve with a fixed CV value is arranged from the snap valve to the gas cylinder inlet, the corresponding pressure drop in the hydrogen injection process is a P valve, and the on-way resistance and local resistance exist in the hydrogen injection process, when the hydrogenation system performs hydrogenation operation at the 70MPa end, the calculation of the equivalent valve CV value is completed by reading the real-time flow of a flow meter in the hydrogenation system, so that the total pressure loss corresponding to the corresponding CV under different flows is recorded; during hydrogenation operation at the 35MPa end, different flows are obtained through a flowmeter, an optimized CV value is obtained through data mapping, and on-way pressure loss P, local pressure loss P and equivalent valve pressure loss P valve under different flows are obtained. The technical problem that a hydrogen adding system cannot obtain pressure information of a gas cylinder inlet due to the fact that a filling port of a hydrogen energy vehicle is not provided with an infrared sending module is solved.

Description

Technical Field

[0001] This application belongs to the technical field of hydrogenation, and particularly relates to a self-learning hydrogenation pressure loss estimation method for a hydrogenation system. Background Art

[0002] With the development of social economy and science and technology, people have increasingly realized the importance of environmental protection. Since hydrogen only produces water vapor after combustion and does not produce any pollutants, and because hydrogen has a high energy density and can store a large amount of energy. Therefore, using hydrogen as fuel can greatly reduce environmental pollution while allowing hydrogen fuel cell vehicles to have a longer driving range.

[0003] Vehicles fueled by hydrogen gradually appear in people's lives, and hydrogen production and hydrogenation stations have emerged as the times require. Currently, a large number of hydrogen storage tanks are set up in hydrogenation stations to store hydrogen fuel. When a vehicle needs to be hydrogenated, the hydrogenation station can extract hydrogen and fill it into the vehicle's hydrogen storage space.

[0004] According to the description of 7.2 Vehicle and Station Dispenser Assumptions in the international standard SAE J2601-2020 "Fueling Protocols for Light Duty Gaseous Hydrogen Surface Vehicles": The vehicle reference pressure drop is 20 MPa from the receptacle to the CHSS, and the station dispenser reference pressure drop is 15 MPa from the break-away to the nozzle exit (combined total pressure drop of 35 MPa) at a mass flow rate 1.5 times the average mass flow rate required to fuel the entire storage capacity in 3 minutes; the maximum peak flow rate specified by this standard is 60 g / s. The vehicle reference pressure drop from the container to the CHSS is 20 MPa, and the station dispenser reference pressure drop from the break-away to the nozzle exit is 15 MPa (total pressure drop of 35 MPa), and the mass flow rate is 1.5 times the average mass flow rate required to fuel the entire storage capacity in 3 minutes.

[0005] For a large-flow hydrogen refueling machine with a maximum peak flow rate greater than 120 g / s, the pressure drop from the breakaway valve of the hydrogen refueling machine to the cylinder inlet directly affects the filling rate and the site energy consumption.

[0006] Currently, an infrared transmission module is installed at the receiving port of 70 MPa vehicles on the market. This module sends information such as the temperature and pressure of the gas cylinder to the hydrogen refueling system according to the international standard protocol SAE J2799. When the hydrogen refueling system refuels a 70 MPa hydrogen energy vehicle, the hydrogen refueling system can obtain the pressure information inside the gas cylinder in real time. At the same time, the hydrogen refueling system can also obtain the temperature and pressure information at its own breakaway valve in real time. The pressure drop from the breakaway valve of the hydrogen refueling system to the cylinder inlet can be obtained through the difference between the two pressures. However, for the receiving port of 35 MPa hydrogen energy vehicles, there is no infrared transmission module, so the hydrogen refueling system cannot obtain the pressure information at the cylinder inlet.

[0007] How to model and estimate the pressure drop from the breakaway valve to the cylinder inlet in a filling system without infrared communication is an urgent problem to be solved. Summary of the Invention

[0008] The purpose of this application is to disclose a self-learning hydrogen refueling pressure loss estimation method for a hydrogen refueling system, which solves the technical problem that the hydrogen refueling system cannot obtain the pressure information at the cylinder inlet due to the absence of an infrared transmission module at the receiving port of the hydrogen energy vehicle, in order to overcome the problems of the prior art.

[0009] The purpose of this application is achieved by the following technical solutions:

[0010] A self-learning hydrogen refueling pressure loss estimation method for a hydrogen refueling system, the hydrogen refueling system includes a hydrogen injection machine, a 35 Mpa hydrogen refueling end and a 70 MPa hydrogen refueling end, and the hydrogen injection machine is connected to the 35 Mpa hydrogen refueling end and the 70 MPa hydrogen refueling end respectively through a breakaway valve;

[0011] The self-learning hydrogen refueling pressure loss estimation method includes:

[0012] Approximate the filling link from the breakaway valve to the cylinder inlet, assume that it is a valve with a fixed CV value from the breakaway valve to the cylinder inlet, and the corresponding pressure drop during the hydrogen injection process is P 阀门 , and there is a frictional resistance and a local resistance during the hydrogen filling process, resulting in corresponding pressure drops of P 沿程 and P 局部 , so the pressure between the breakaway valve and the inlet of the vehicle-mounted gas cylinder can be expressed as:

[0013] P 拉断阀 -P 沿程 -P 局部 -P 阀门 =P 气瓶

[0014] When the hydrogenation system performs end - hydrogenation operation at 70 MPa, the hydrogenation system obtains the pressure information inside the gas cylinder in real time. At the same time, the hydrogenation system can also obtain the pressure information at its own breakaway valve in real time. The total pressure loss from the breakaway valve of the hydrogenation system to the gas cylinder inlet can be obtained through the difference between the two pressures, that is, P 沿程 +P 局部 +P 阀门 , by reading the real - time flow rate of the flowmeter in the hydrogenation system, the equivalent valve CV value is calculated, and self - learning is performed once every 100 ms, so as to record the total pressure loss corresponding to the corresponding CV at different flow rates;

[0015] When performing end - hydrogenation operation at 35 MPa, different flow rates are obtained through the flowmeter, and the preferred CV value is obtained through data mapping, and the frictional pressure loss P 沿程 , local pressure loss P 局部 and equivalent valve pressure loss P 阀门 are obtained.

[0016] According to a preferred embodiment, the self - learning hydrogenation pressure loss estimation method further includes: based on the initial pressure of the breakaway valve in the hydrogenation system and the total pressure loss at the 35 MPa hydrogenation end, the pressure value at the vehicle - mounted end bottle valve is obtained.

[0017] According to a preferred embodiment, the pressure drop caused by frictional resistance is:

[0018]

[0019] where l is the pipe length, d is the pipe diameter, g is the acceleration due to gravity, is the flow rate, A is the cross - sectional area of the pipe, and λ is the frictional resistance coefficient.

[0020] According to a preferred embodiment, the pressure drop caused by local resistance is:

[0021]

[0022] where, is the local resistance coefficient.

[0023] According to a preferred embodiment, the pressure loss of compressible hydrogen passing through the valve under non - turbulent conditions is related to the flow rate:

[0024]

[0025] where N and Sg are constants, P 阀门 is the real - time pressure loss or equivalent valve pressure loss during the filling process, is the flow rate, obtained through the flowmeter; P 拉断阀 and T 拉断阀 can be obtained through the pressure transmitter and temperature transmitter at the front end of the breakaway valve, Cv They are characteristic parameters of the valve.

[0026] According to a preferred embodiment, the temperature value at the bottle mouth valve on the vehicle-mounted side is calculated based on the relationship among pressure, density, and enthalpy values.

[0027] The main solution of the present application and its various further alternative solutions can be freely combined to form multiple solutions, all of which are solutions that can be adopted and claimed in the present application. Those skilled in the art can understand that there are various combinations according to the prior art and common general knowledge after understanding the solution of the present application, and all of them are technical solutions to be protected by the present application, which will not be enumerated here.

[0028] Advantages of the present application:

[0029] The method of the present application solves the technical problem that the hydrogen filling system cannot obtain the pressure information at the cylinder inlet because there is no infrared transmission module at the receiving port of the hydrogen energy vehicle, and effectively obtains the pressure information and temperature information at the cylinder inlet of the 35MPa hydrogen energy vehicle, thus ensuring the safety of the hydrogen injection process. Description of the Drawings

[0030] Figure 1 It is a schematic structural diagram of the hydrogen filling system of the present application;

[0031] Figure 2 It is a schematic equivalent structural diagram of the hydrogen injection pipeline. Detailed Embodiments

[0032] The following specific examples illustrate the embodiments of the present application. Those skilled in the art can easily understand other advantages and effects of the present application from the content disclosed in this specification. The present application can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present application. It should be noted that, without conflict, the following embodiments and the features in the embodiments can be combined with each other.

[0033] It should be noted that: similar reference numerals and letters represent similar items in the following drawings. Therefore, once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0034] In the description of the present application, it should be noted that the orientation or positional relationship indicated by terms such as "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the drawings, or the orientation or positional relationship in which the product of this application is customarily placed during use. It is only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation to the present application. In addition, terms such as "first", "second", "third", etc. are only used for distinguishing descriptions and cannot be understood as indicating or implying relative importance.

[0035] In addition, terms such as "horizontal", "vertical", "hanging", etc. do not mean that the components are required to be absolutely horizontal or hanging, but can be slightly inclined. For example, "horizontal" only means that its direction is more horizontal relative to "vertical", and does not mean that the structure must be completely horizontal, but can be slightly inclined.

[0036] In the description of the present application, it should also be noted that unless otherwise clearly specified and limited, the terms "set", "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific situations.

[0037] In addition, it should be pointed out in the present application that in the present application, if the specific structures, connection relationships, positional relationships, power source relationships, etc. involved are not specifically written, then the structures, connection relationships, positional relationships, power source relationships, etc. involved in the present application are all known to those skilled in the art on the basis of the prior art without creative labor.

[0038] Embodiment 1

[0039] Reference Figure 1 and Figure 2 As shown in and, a self-learning hydrogenation pressure loss estimation method for a hydrogenation system is shown in the figure. The hydrogenation system includes a hydrogen injection machine, a 35 Mpa hydrogenation end, and a 70 MPa hydrogenation end. The hydrogen injection machine is connected to the 35 Mpa hydrogenation end and the 70 MPa hydrogenation end respectively through a pull-off valve.

[0040] Preferably, the self-learning hydrogenation pressure loss estimation method includes:

[0041] Approximate the filling link from the pull-off valve to the cylinder inlet. Assume that from the pull-off valve to the cylinder inlet is a valve with a fixed CV value, and the corresponding pressure drop during the hydrogen injection process is P 阀门 , such asFigure 2 As shown. And there are frictional resistance and local resistance during the hydrogen filling process, and the corresponding pressure drop is P 沿程 and P 局部 . Therefore, the pressure from the breakaway valve to the inlet of the vehicle-mounted gas cylinder can be expressed as:

[0042] P 拉断阀 -P 沿程 -P 局部 -P 阀门 =P 气瓶 .

[0043] When the hydrogen filling system performs hydrogen filling operation at the 70 MPa end, the hydrogen filling system can obtain the pressure information in the gas cylinder in real time. At the same time, the hydrogen filling system can also obtain the pressure information at its own breakaway valve in real time. Through the difference between the two pressures, the total pressure loss from the breakaway valve of the hydrogen filling system to the gas cylinder inlet can be obtained, that is, P 沿程 +P 局部 +P 阀门 . By reading the real-time flow rate of the flowmeter in the hydrogen filling system, the equivalent valve CV value is calculated, and self-learning is performed every 100 ms, so as to record the total pressure loss corresponding to the corresponding CV at different flow rates.

[0044] Specifically, the pressure drop caused by frictional resistance is:

[0045]

[0046] where l is the pipeline length, d is the pipeline diameter, g is the acceleration of gravity, is the flow rate, A is the cross-sectional area of the pipeline, and λ is the frictional resistance coefficient.

[0047] The pressure drop caused by local resistance is:

[0048]

[0049] where, is the local resistance coefficient.

[0050] The pressure loss of compressible hydrogen passing through the valve under non-turbulent conditions is related to the flow rate:

[0051]

[0052] where N and Sg are constants, P 阀门 is the real-time pressure loss or equivalent valve pressure loss during the filling process, is the flow rate, obtained through the flowmeter; P 拉断阀 and T 拉断阀 can be obtained through the pressure transmitter and temperature transmitter at the front end of the breakaway valve, and C v is the characteristic parameter of the valve.

[0053] Furthermore, during the hydrogenation operation at the 35 MPa end, different flow rates are obtained through a flow meter, and the optimal CV value is obtained through data mapping, and the pressure loss P along the way under different flow rates is obtained. 沿程 , the local pressure loss P 局部 and the equivalent valve pressure loss P 阀门 . Among them, during the hydrogenation operation at the 35 MPa end, the pressure loss P along the way 沿程 is related to the real-time flow rate, the local pressure loss P 局部 is related to the real-time flow rate, and the equivalent valve pressure loss P 阀门 is related to the real-time flow rate and the CV value.

[0054] Preferably, the self-learning hydrogenation pressure loss estimation method further includes: based on the initial pressure of the breakaway valve in the hydrogenation system and the total pressure loss at the 35 MPa hydrogenation end, the pressure value at the vehicle-mounted end bottle valve is obtained.

[0055] Preferably, during the 70 MPa vehicle filling, the CV value self-learning process includes:

[0056] P 阀门 = P 拉断阀 - P 沿程 - P 局部 - P 气瓶 - ΔP, where ΔP is the compensation pressure of a specific hydrogen filling pipeline, and the value range is -1 to 1 MPa.

[0057] When the CV value is set to the initial value (1*e-5), the calculated P 阀门 and the pressure P 真 monitored in real time during the 70 MPa filling process are different. In order to quickly obtain the optimal CV value, the derivative direction is used to quickly approximate the true value. That is, the Euclidean distance is used in the model to represent the error ξ, that is At this time

[0058] When the flow rate is known, P 沿程 , P 局部 is independent of the approximate valve CV value, P 拉断阀 , P 气瓶 and are obtained through known values, so P 拉断阀 - P 沿程 + P 局部 - P 气瓶 is a known value, so that P 阀门 = α·C v + ΔP, where α is 's deformation writing method, that is, α is a function of the flow rate .

[0059] The flow value collected from the flowmeter at the current moment is Then α is a definite value, and the variable is C at this time v and ΔP; Given P 阀门 = α·C v +ΔP, then Then

[0060] Set the step size for each update to β = 0.1, that is, C v新 = C v +β·α·(P 阀门 -P 真 ), ΔP 新 = ΔP + β·(P 阀门 -P 真 ).

[0061] For example: P 阀门 = α·C v +ΔP, when the flow is constant for a period of time, α is also a fixed value, as shown in Table 1.

[0062] Table 1

[0063] α Cv ΔP <![CDATA[P 阀门 > P true ξ 1.5 …… …… …… 2 …… 1.5 0.8 0.2 1.4 2 0.18 1.5 0.88 0.22 1.54 2 0.11 1.5 0.968 0.242 1.694 2 0.04

[0064] Therefore, when , the error is less than the set value of 0.05 at this time. Therefore, the optimal CV value is 0.968 and the closest ΔP is 0.242 at this time;

[0065] And so on, during the filling process at 70 MPa, automatically learn the cv values and ΔP values under different types. And store the optimal cv and optimal ΔP at the same moment.

[0066] During filling at 35 MPa, find the optimal cv value and optimal ΔP value according to the measured flow . If they do not exist in the cv value and ΔP value table, interpolation method is used for calculation (the calculation formula for ΔP is similar):

[0067]

[0068] Obtain C v优 、ΔP 优 , then the P 拉断阀 、P 沿程 、P 局部 、P 阀门 under the 35 MPa filling circuit can be obtained, so as to obtain the pressure P 气瓶 of the 35 MPa bottle valve.

[0069] Further, the temperature value at the bottle mouth valve on the vehicle-mounted side is calculated based on the relationships among pressure, density, and enthalpy value. The heat transfer equation is specifically expressed as:

[0070]

[0071] where λ represents the thermal conductivity, T represents the temperature, t represents the time, x, y, and z respectively represent the length, thickness, and diameter of the pipeline, q represents the heat flux, ρ represents the density of hydrogen, and c p represents the specific heat at constant pressure;

[0072] By making assumptions about the gas cylinder and the pipeline, the heat transfer equation is simplified:

[0073]

[0074] Using the boundary conditions, the temperature distribution of the pipeline from the breakaway valve to the gas cylinder inlet can be calculated.

[0075] The calculations of temperature and pressure are performed in a periodic cycle with a time step of 100 ms until the filling process is completed.

[0076] The above are only the preferred embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, and improvements made within the spirit and principles of the present application shall be included within the protection scope of the present application.

Claims

1. A self-learning hydrogenation pressure loss estimation method for a hydrogenation system, characterized in that: The hydrogenation system comprises a hydrogenation machine, a 35 MPa hydrogenation end and a 70 MPa hydrogenation end, wherein the hydrogenation machine is connected to the 35 MPa hydrogenation end and the 70 MPa hydrogenation end respectively via a breakaway valve; The self-learning hydrogenation pressure loss estimation method comprises: The filling link from the breakaway valve to the cylinder inlet is approximated, assuming that there is a valve with a fixed CV value from the breakaway valve to the cylinder inlet, and the corresponding pressure drop during the hydrogen injection process is P 阀门 , and there are resistances along the way and local resistances during hydrogen filling, resulting in a corresponding pressure drop of P 沿程 and P 局部 , so the pressure from the breakaway valve to the inlet of the vehicle gas cylinder can be expressed as: P 拉断阀 -P 沿程 -P 局部 -P 阀门 =P 气瓶 When the hydrogenation system is performing hydrogenation at the 70MPa end, the hydrogenation system obtains the pressure information in the gas cylinder in real time. At the same time, the hydrogenation system can also obtain the pressure information at its own breakaway valve in real time. The total pressure loss from the breakaway valve of the hydrogenation system to the gas cylinder inlet can be obtained through the two pressure differences, that is, P 沿程 +P 局部 +P 阀门 , by reading the real-time flow rate of the flow meter in the hydrogenation system, the equivalent valve CV value calculation is completed, and self-learning is performed every 100ms to record the total pressure loss corresponding to the corresponding CV under different flow rates; During the hydrogenation operation at 35MPa, different flow rates are obtained through the flow meter, and the optimal CV value is obtained through data mapping, and the pressure loss P along the process at different flow rates is obtained. 沿程 、Local pressure loss P 局部 and equivalent valve pressure loss P 阀门 .

2. The self-learning hydrogenation pressure loss estimation method according to claim 1, characterized in that: The self-learning hydrogenation pressure loss estimation method also includes: based on the initial pressure of the breakaway valve in the hydrogenation system and the total pressure loss at the 35MPa hydrogenation end, obtaining the pressure value at the vehicle-mounted bottle mouth valve.

3. The self-learning hydrogenation pressure loss estimation method according to claim 1, characterized in that: The pressure drop caused by the resistance along the way is: l is the length of the pipe, d is the diameter of the pipe, g is the acceleration due to gravity, is the flow rate, A is the cross-sectional area of ​​the pipe, and λ is the resistance coefficient along the way.

4. The self-learning hydrogenation pressure loss estimation method according to claim 3, characterized in that: The pressure drop due to local resistance is: in, is the local drag coefficient.

5. The self-learning hydrogenation pressure loss estimation method according to claim 4, characterized in that: The pressure loss of compressible hydrogen passing through the valve under non-turbulent conditions is related to the flow rate: Where N and Sg are constants, P 阀门 is the real-time pressure loss during the filling process or equivalent valve pressure loss, is the flow rate, obtained through the flow meter; P 拉断阀 and T 拉断阀 It can be obtained through the pressure transmitter and temperature transmitter at the front end of the breakaway valve, C v is the characteristic parameter of the valve.

6. The self-learning hydrogenation pressure loss estimation method according to claim 2, characterized in that: The temperature value at the bottle mouth valve on the vehicle is calculated based on the relationship between pressure, density and enthalpy.

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